Uworld Qbank Flashcards

Question

ANOVA | analysis of variance

Answer 1

compares the difference between the means of 2+ groups | t-test compares the diff btwn means of 2 groups

Answer 2

Rubeola (measles) or Rubella (German measles) Postauricular lymphadenopathy --> rubella (togavirus)

Answer 3

Fifampin, phenobarbital and phenytoin are universal enhancers of the cytochrome P450 pathway --> decreased efficacy of warfarin Cimetidine, amiodarone, TMP-SMX inhibit warfarin metabolism

Answer 4

Herpes zoster post-herpetic neuralgia is the most common neurological complication of varicella zoster virus infection

Answer 5

narrow spectrum anticonvulsant + first line agent for benign essential tremor active metabolites include phenobarbital (which can be monitored in blood) and phenylethylmalonamide Sedation = potential side effect during drug initiation/toxicity

Answer 6

catabolic, causing muscle weakness, skin thinning, impaired wound-healing, osteoporosis, and immunosuppression Increase liver protein synthesis, specifically the enzymes involved in gluconeogenesis and glycogenesis + Peripheral antagonism of the effects of insulin --> hyperglycemia

Answer 7

increase the frequency of opening of the CNS GABAa receptor-chloride channels and have anxiolytic, anticonvulsant, and muscle relaxant effects as well as sedative-hypnotic effects compare to: Barbituates - increase the duration of opening of the GABAa receptor-chloride channel, longer half-lifes, hangover effect decreases their use for insomnia

Answer 8

parenteral B21 administration Poor absorption secondary to gastric atrophy, intrinsic factor deficiency, or terminal ileal disease is the most common cause of deficiency, with dietary vitamin B12 deficiency far less common

Answer 9

metabolized by cytochrome P450 (except pravastatin) coadministration with drugs that inhibit its metabolism (ex. erythromycin) --> increased incidence of statin induced myopathy and rhabdomyolysis acute renal failure is a possible sequelea of rhabdo

Answer 10

low C1 esterase inhibitor activity leads to increases in bradykinin activity ACE inhibitors should not be used in these patients (ACE converts bradykinin to inactive metabolites).

Answer 11

Essential to viral invasion of cells and the viral tropism for specific tissues is the initial attachment of the virion envelope or capsid surface proteins to the complementary host cell surface receptors. Many viruses bind to normal host cell plasma membrane receptors in order to enter host cells. Known host cell receptor – virion/virion protein binding specificities include: CD4 and HIV gp120; CD21 and EBV gp350; and erythrocyte P antigen and parvovirus B19

Answer 12

Left-sided heart disease can cause pulmonary hypertension by increasing pulmonary venous pressure and congestion. This leads to a passive increase in pulmonary arterial pressure, which is made worse by reactive vasoconstriction and structural remodeling of the pulmonary vasculature secondary to impaired nitric oxide availability and increased endothelin expression.

Answer 13

MAC measure of the potency of an inhaled anesthetic (inversely proportional) concentration of the anesthetic in the alveoli that renders 50% of the pts unresponsive to painful stimuli (ED50)

Answer 14

more proximal levels have increasing amount of white matter (around the butterfly) and more ovoid sections; lower cervical and lumbosacral regions have large ventral horns; thoracic and early lumbar sections (T1-L2) contain lateral grey matter horns (sympathetic preganglionic neurons)

Answer 15

decreased serum ferritin, increased serum transferrin, and increased total iron binding capacity Anemia in a woman of childbearing age is most commonly caused by iron deficiency secondary to menstrual blood loss

Answer 16

increased bone resorption PTH acts on osteoclasts by an indirect method, it is the osteoblasts that have PTH receptors. PTH causes osteoblasts to increase the production of RANK-ligant and monocyte colony stimulating factor (M-CSF) these two factors stimulate osteoclastic presursors to differentiate into bone-resorbing, mature osteoclasts. PTH increases serum calcium level and decreases serum phosphate level (lost in urine)

Answer 17

includes Ras protein, a G-protein that exists in inactive (GDP containing) and active (GTP containing) forms Mutated Ras --> tumors

Answer 18

multiple endocrine neoplasia type 2B medullary thyroid cancer pheochromocytomas mucosal neuromas marphanoid habitus

Answer 19

--> results in QT prolongation The major cardiac pathophysiological consequences of QT prolongation is an increased risk of episodic polymorphic ventricular tachycardia, including torsades de pointes.

Answer 20

associated with neurofibromatosis type 2, an autosomal dominant condition caused by mutation of the NF-2 gene on chromosome 22

Answer 21

X-linked recessive myopathy results from deletion of dystrophin gene Dystrophin is a protein that allows interaction between extracellular connective tissue and the intracellular contraction apparatus manifests in boys 2-5 years old with proximal muscle weakness and enlargement of the distal muscles

Answer 22

Age 95% of affected children, but only 60% of affected adults, recover completely

Answer 23

upper GI ulcerations (jejunal ulcers are specific), abdominal pain and diarrhea

Answer 24

The chi-square test for independence is used to test the association between 2 categorical variables. In the case of an exposure status and a binomial outcome, patients are divided into 2 groups based on exposure, and the number of pts that experience each outcome is recorded in a 2x2 table

Answer 25

a1-mediated vasoconstriction prevents cerebral hypoperfusion upon standing. a-adrenergic blockers disrupt this mechanism and cause orthostatic hypotension

Answer 26

occurs when tumors with a high cell turnover are treated with chemo The lysis of tumor cells causes intracellular ions, such as potassium and phosphorus, and uric acid (metabolite of tumor nucleic acid) to be released into serum Uric acid is soluble at physiologic pH, but it can precipitate in the normally acidic environment of distal tubules and collecting ducts prevention: urine alkalinization and hydration

Answer 27

mediated by T-lymphocytes of the donor tissue that are sensitized against MHC antigens of recipient. Skin, liver and intestine are commonly involved develops within 1 week of transplant in severe cases - skin desquamation

Answer 28

one of the less mature defense mechanisms redirect emotions from the person/object causing them to a more acceptable, but still inappropriate, person/object ex. angry at wife, punch wall

Answer 29

fraction of plasma flowing through the glomeruli that is filtered across the glomerular capillaries into Bowman's space FF=GFR/RPF renal plasma flow can be determined from renal blood flow by multiplying the renal blood flow by (1-hematocrit)

Answer 30

The left atrium forms the majority of the posterior surface of the heart and resides adjacent to the esophagus Enlargement of the left atrium can compress the esophagus and cause dysphagia

Answer 31

lies posterior to the esophagus and left atrium clearly visualized by transesophageal echocardiography allowing for the detection of abnormalities such as dissection or aneurysm

Answer 32

All the skin from the umbilicus down, including the anus (up to the dentate/pectinate line) but excluding the posterior calf, drains to the superficial inguinal lymph nodes (testes drain to abdominal aortic lymph nodes)

Answer 33

Insulin is the medication of choice for the tx of gestational diabetes in pts for whom diet and light exercise have failed to control blood glucose levels Oral hypoglycemic medications are avoided b/c risk of fetal hyperinsulinemia and hypoglycemia

Answer 34

PCWP measures the left atrial end diastolic pressure (LAEDP) Normal: LAEDP ~ LV end-diastolic pressure (LVEDP) Mitral stenosis elevates the LAEDP and PCWP relative to the LVEDP

Answer 35

mononuclear, parenchymal infiltration with well-developed germinal centers on histology Most common cause of hypothyroidism (in iodine sufficient areas)

Answer 36

allosteric activator of gluconeogenesis that acts by increasing the activity of pyruvate carboxylase

Answer 37

Patients with adult-type coarctation of the aorta commonly die of hypertension-associated complications, including left ventricular failure, ruptured dissecting aortic aneurysm, and intracranial hemorrhage. These pts are at increased risk for ruptured intracranial aneurysms because of the increased incidence of congenital berry aneurysms of the circle of willis as well as aortic arch hypertension

Answer 38

conversion of norepinephrine to epinephrine occurs in adrenal medulla PNMT transcription is unregulated by cortisol (drainage of adrenal cortex goes through medulla, so there's a high concentration --> catecholamine content 80% epic

Answer 39

Oral administration subjects a drug to a large amount of first-pass metabolism (metabolized by liver and doesn't reach systemic circulation), whereas IV, sublingual, and rectal administration bypasses some or all of this process and allows more drug to reach the systemic circulation

Answer 40

Enterobiasis occurs most frequently in school-age children and presents with perianal pruritus. Diagnosis is made by the scotch tape test. Albendazole is the first-line treatment, with pyrantel permeate as an alternative agent preferred in pregnant patients

Answer 41

Informal treatment to friends is ethically problematic, should be limited to emergency situations or when no other physical is available

Answer 42

Antibody-mediated (type II) hypersensitivity caused by pre-existing into-ABO antibodies that bind antigens on transfused donor erythrocytes --> complement activation: erythrocyte lysis, vasodilation, symptoms of shock common findings: fever, hypotension, chest and back pain and hemoglobinuria

Answer 43

Dehydration --> decrease in RPF and GFR compensatory activation of the renin-angiotensin mechanism in response to hypotension --> constriction of the efferent arteriole to maintain GFR as best as possible. Therefore, FF increases

Answer 44

HPV types 16, 18 and 31 are strongly associated with anal and cervical squamous cell carcinoma. HIV infection increases the prevalence of HPV infection and the risk of anal carcinoma; this risk is further augmented in men who have sex with men

Answer 45

non-beta cell pancreatic islet cell tumors that hypersecrete VIP --> 'pancreatic cholera', 'WDHA syndrome' (watery diarrhea, hypokalemia, achlorhydria) VIP increases intestinal chloride loss in the stool, which causes excess losses of the accompanying water, sodium and potassium as well VIP also inhibits gastric acid secretion Tx: Somatostatin inhibits the secretion of VIP

Answer 46

proper hand washing, full barrier precautions during insertion of a central line, chlorhexidine for skin disinfection, avoidance of the femoral insertion site, removal of catheter when no longer needed

Answer 47

Nasal In the general population at any given time, 25-30% of individuals have nasal colonization with Staphylococcus aureus. The anterior nares are the most common site of colonization for both methicillin-sensitive and methicillin-resistant staph aureus

Answer 48

aka Vero cytotoxins produced by EHEC (enterohemorrhagic E. coli), nearly identical to the Shiga toxin produced by Shigella dysenteriae Inhibit the 60s ribosomal subunit in human cells, thereby blocking protein synthesis by preventing binding of tRNA [this differs from diphtheria toxin and exotoxin A of pseudomonas, which act on EF-2 not the 60S ribosomal subunit

Answer 49

Children aged 1-3 years who develop gingivostomatitis characterized by ulcerative lesions with intranuclear inclusions are likely experiencing primary infection with herpes simplex virus type 1 (HSV-1). HSV-1 and other herpesviruses are enveloped and possess double-stranded DNA genomes

Answer 50

antimyobacterial agent that specifically inhibits the synthesis of mycolic acids Mycelia acids are essential components of the unique mycobacterial peptidoglycan cell wall. Without mycolic acids, the mycobacteria lose their acid-fastness and become unable to synthesize new cell walls or multiply

Answer 51

"Blind as a bat, mad as a hatter, red as a beet, hot as a hare, dry as a bone, the bowel and bladder lose their tone, and the heart runs alone" Atropine is a reversible cholinergic antagonist that acts selectively on muscarinic receptors. Its effects can be reversed by cholinesterase inhibitors (physostigmine) Note: Jimson Weed (Datura stramonium) poisoning, also called 'Gardener's mydriasis' is similar to atropine poisoning

Answer 52

centrally acting anti-cholinergic used to treat idiopathic and drug-induced Parkinson's

Answer 53

block the effect of ACE, decreasing angiotensin II and aldosterone levels By decreasing angiotensin II levels, ACE inhibitors directly interrupt negative feedback loops, thus increasing renin and angiotensin I levels. Without effective ACE, bradykinin metabolism decreases and bradykinin levels will increase

Answer 54

Polyene antifungal and the drug of choice for oropharyngeal candidiasis in pts without advanced immunodeficiency Acts by binding ergosterol in the fungal cell membrane, causing the formation of pores and leakage of fungal cell contents Not absorbed from the GI tract and administered as an oral 'swish and swallow' agent

Answer 55

X-inactivation occurs in genetically normal females and results in conversion of the inactivated X chromosome into compact heterochromatin (Barr body) Heterochromatin is condensed chromatin composed of heavily methylated DNA in tight association with deacetylated histones. It has a low level of transcriptional activity In contrast, euchromatin is loosely arranged and exhibits a high level of transcriptional activity

Answer 56

Rare pancreatic islet tumor Somatostatin is secreted from pancreatic 'delta cells' and decreases the secretion of secretion, cholecystokinin, glucagon, insulin and gastrin Gallbladder stones form because of poor gallbladder contractility, which is secondary to inhibition of cholecystokinin release

Answer 57

presents with brief episodes of sudden and severe 'electric shock-like' or 'stabbing' pain in the distribution of CN V (particularly V2 and V3) Carbamazapine is the drug of choice Inhibits neuronal high-frequency firing by reducing the ability of Na channels to recover from inactivation Can cause aplastic anemia P450 inducer

Answer 58

Associated with HTN Located in basal ganglia, cerebellum, thalamus, pons Size

Answer 59

Associated with ADPKD, Ehlers-Dalos syndrome, HTN Located in circle of willis size 2-25mm Rupture results in subarachnoid hemorrhage sx include sudden severe headache, focal neuro defecits uncommon

Answer 60

Initiated by repetitive endothelial injury, which leads to a chronic inflammatory state in the underlying intima of large elastic arteries as well as large and medium-size muscular arteries

Answer 61

rare inborn errors of metabolism where peroxisomes are either absent or nonfunctional very long chain fatty acids with branched points at odd-numbered C can not undergo mitochondrial beta-oxidation; these fatty acids are metabolized by a special form of beta oxidation or by alpha oxidation within peroxisomes These diseases commonly lead to neurologic defects from improper CNS myelination

Answer 62

catecholamine-secreting tumor that presents with episodic hypertension, tachycardia, headaches, diaphoresis and tremors. Detection of elevated levels of catecholamines and metanephrines (catecholamine breakdown products) in the urine or plasma confirms diagnosis

Answer 63

rare neoplasm that arises from the pleura or peritoneum associated with ASBESTOS exposure (shipbuilding) Hemorrhagic pleural effusions and pleural thickening are characteristic EM = gold standard for diagnosis: tumor cells with numerous, long, slender microvilli and abundant tonofilaments

Answer 64

Unmineralized osteoid matrix and widened osteoid seams bowed legs, rachitic rosary, Harrison's sulci, craniotabes, and growth retardation

Answer 65

occurs due to irregular, chaotic electrical activity within the atria presents with absent P waves, irregularly irregular R-R intervals and narrow QRS complexes AV node refractory pd regulates the number of atrial impulses that reach the ventricle and determines the ventricular contraction rate in conditions where the atria undergo rapid depolarization

Answer 66

small ischemic infarcts (

Answer 67

Ca++ Glycogen degradation is coupled with skeletal muscle contraction due to calcium-mediated myophosphorylase activation. Increased Ca++ in the cytosol allosterically activates phosphorylase kinase, which then phosphorylates (activates) muscle phosphorylase

Answer 68

usually develop due to increased intraluminal pressure, composed of mucosa and submucosa sigmoid colon most commonly asymptomatic or manifest with painless rectal bleeding or acute diverticulitis risk factor: chronic constipation

Answer 69

Precursor B-ALL: TdT+, CD10+, CD19+ Precursor T-ALL: TdT, CD1a, CD2/3/4...

Answer 70

suppresses bacterial protein synthesis by binding the ribosomal 50S subunit and inhibiting the peptide transferase enzyme can lead to dose-dependent (reversible) and dose independent (irreversible) aplastic anemia (bone marrow failure due to hematopoietic stem cell deficiency CD34+)

Answer 71

can occur in individuals suffering from fat malabsorption or abetalipoproteinemia increases susceptibility of the neuronal and erythrocyte membranes to oxidative stress manifests as neuromuscular disease and hemolytic anemia

Answer 72

destroy the parasite via antibody-dependent cell-mediated cytotoxicity with enzymes from their cytoplasmic granules Eosiniphils also regulate type 1 hypersensitivity reactions

Answer 73

COPD encompasses a spectrum of disease between chronic bronchitis and emphysema Emphysema: destruction of interalveolar walls and decreased lung elastic recoil --> increased residual volume, functional residual capacity and total lung capacity

Answer 74

enzyme of the urea cycle that produces urea and ornithine from arginine

Answer 75

Pelvic fracture - Posterior urethra damage Straddle injury - Anterior urethra damage symptoms: Inability to void with full bladder sensation, high-riding boggy prostate, and blood at the urethral meatus Foley catheter is contraindicated

Answer 76

Body fat redistribution subcutaneous lipoatrophy involving the face/extremities is associated with nucleoside reverse transcriptase inhibitors (stavudine, zidovudine) central fat accumulation in the trunk and viscera can occur with any HAART regimen

Answer 77

presence of endometrial glands and stroma outside the uterus asymptomatic or severe dysmenorrhea, dyspareunia and infertility

Answer 78

Simultaneous development of stroke, intestinal or foot ischemia and renal infarction These emboli may arise from left atrial clots, left ventricular clots, valvular vegetations, or aortic atherosclerotic plaques

Answer 79

3 main types: food borne, wound, infant In food-borne botulism, botulinum neurotoxin in food (produced by the organism Clostridium botulinum) prevents release of acetylcholine from nerve terminals at the neuromuscular junction, thereby preventing muscular contraction

Answer 80

sex-cord stromal tumors that secrete estrogen Histology: Call-Exner bodies

Answer 81

osmotic laxative Diarrhea associated with lactase deficiency is also osmotic Magnesium hydroxide is another osmotic laxative often used (less evidence though)

Answer 82

Tx = Sodium bicarbonate TCAs (tricyclic anti-depressants) can have quinidine-like effect on the cardiac conduction system, potentially causing QRS and QT prolongation and cardiac dysrhythmias (inhibit fast Na channels)

Answer 83

``` Found in 40% of pts with: CREST syndrome (limited scleroderma) manifests with Calcinoshs, Raynaud's phenomenon, Esophageal dysmotility, Sclerodactyly and Telangiectasias ``` Anti-DNA topoisomerase 1 (Scl-70) ab are specific for systemic sclerosis

Answer 84

cultured on cysteine-tellurite agar, resultant colonies are black in color The bacterium produces intracellular polyphosphate granules, called metachromatic granules, that can be detected on microscopy after methylene blue staining

Answer 85

symmetrical proximal muscle weakness muscle biopsy: inflammation, necrosis, regeneration of muscle fibers preceding damage to myocytes with subsequent over-expression of MHC class I proteins on the sarcolemma leads to infiltration with CD8+ T lymphocytes and myocyte damage

Answer 86

intimal hyperplasia and fibrosis, predominantly mediated by reactive smooth muscle cells that migrate from the media to the intima

Answer 87

The central airway pressure-volume curve is the functional residual capacity of the lungs, it identifies the resting state where the airway pressure equals 0 At the FRC, the intrapleural pressure is negative with a value of -5 cm H2O (chest wall tendency to expand opposes lungs tendency to collapse)

Answer 88

B hemolytic, bacitracin-susceptible, pyrrolidonyl arylamidase-positive Glomerulonephritis is associated with prior strep pharyngeal or skin infection Acute rheumatic fever is associated with prior streptococcal pharyngitis (but not skin infection)

Answer 89

Apical holosystolic murmur radiating to the axilla Left ventricular afterload is the major determinant of the forward-to-regurgitant flow ratio in patients with mitral regurgitation Decreasing afterload will increase forward flow while reducing regurgitant flow

Answer 90

The congenital rubella syndrome is predominantly characterized by neonatal defects of the head (microcephaly, mental retardation), eyes (cataracts), ears (deafness) and heart/CV system (PDA) Vaccine for children, non-pregnant females of childbearing age with live, attenuated rubella virus vaccine

Answer 91

causes both upper and lower motor neuron lesions Loss of neurons of the anterior horns of the spinal cord (LMN lesion) causes muscle weakness and atrophy. Demyelination of the lateral corticospinal tract (UMN lesion) leads to spasticity and hyperreflexia

Answer 92

increase preload and cause a rightward widening of the PV loop (the PV loop represents the relationship btwn pressure and volume in the left ventricle during systole and diastole)

Answer 93

High synovial fluid white blood cell count and absent crystals on microscopic examination suggest bacterial joint infection Septic arthritis requires immediate antibiotic treatment to prevent joint destruction, osteomyelitis and sepsis Give ceftriaxone

Answer 94

corresponds to ventricular depolarization (phase 0 on AP graph) Ventricular myocyte depolarization is mediated by inward sodium movement and can be modulated by class 1 antiarrhythmics

Answer 95

acutely decreases GFR and glomerular FF

Answer 96

The cephalic and gastric phases stimulate gastric acid secretion, while intestinal influences tend to reduce gastric acid secretion

Answer 97

Procainamide and hydrazine have the highest risk lupus-like symptoms and positive ANA and anti-histone antibodies (anti-dsDNA ab rarely seen)

Answer 98

High-dose glucocorticosteroids such as prednisone decrease the severity of inflammation and decrease extra ocular volume conventional antithyroid drugs do not improve ophthalmopathy

Answer 99

Selective COX2 inhibitor (preferentially expressed at sites of inflammation) potent anti-inflammatory effects without the side effect of bleeding and GI ulceration associated with non-selective COX inhibitors Selective COX 2 inhibitors do not impair platelet function because platelets predominantly express COX 1 (physiological role in tissues)

Answer 100

small, erythematous, possibly hemorrhagic merciless that may appear on the soles of the feet and palms of the hands in a pt with bacterial endocarditis (blowing holosystolic murmur over apex + dyspnea + fatigue --> mitral regurgitation fever + acuity --> bacterial endocarditis)

Answer 101

hilar adenopathy, pulmonary disease, constitutional symptoms Histology: non-caveating granulomas (distinguish it from TB)

Answer 102

arises at the level of the middle cerebellar peduncle at the lateral aspect of the mid-pons Infarcts involving the anterior portion of the medial pons can produce dysarthria and contralateral ataxic hemiparesis

Answer 103

positive in most cases of EBV associated mono (serum heterophile antibodies that agglutinate with erythrocytes from unrelated species) In immunocompetent pts with a heterophile antibody-negative mononucleosis-like syndrome, the most likely diagnosis is cytomegalovirus infection

Answer 104

most noticeable when the affected eye looks down toward the nose usually caused by Trochlear nerve (CN IV) palsy

Answer 105

slow growing, well-circumscribed benign tumor Psammoma bodies (core of dense calcification with surrounding collagen-fiber bundles) are characteristic

Answer 106

pancytopenia, bone marrow replaced by fat cells and fibrous stroma, absence to splenomegaly to distinguish between aplastic anemia and myeloproliferative diseases that also cause pancytopenia, a bone marrow biopsy is required

Answer 107

Galacticol accumulates in the lens of pts, causing osmotic damage --> cataract formation Galacticol is formed from excess circulating galactose in galactosemia by aldose reductase

Answer 108

preoccupation with a perceived defect in appearance and repetitive behaviors in response to the preoccupation. Can present with absent insight/delusional beliefs and result in significant psychosocial dysfunction

Answer 109

one or more delusions in the absence of other psychotic symptoms. Behavior is not obviously bizarre and functioning is not significantly impaired apart from the direct impact of the delusions

Answer 110

proximal transport of mucus by ciliated epithelial cells (mucoclliary clearance) distal to the terminal bronchioles - macrophages Mucus-secreting cells are present to the level of the larger bronchioles, after which club cells become the prominent secretory cell type

Answer 111

X-linked disorder resulting from deficiency of NADPH oxidase, the enzyme responsible for formation of reactive oxygen species in phagosomes. Neutrophils affected by this disorder are unable to kill catalase-producing organisms, resulting in recurrent bacterial and fungal infections that frequently involve the lungs, skin and lymph nodes

Answer 112

"selective estrogen receptor modulators" (SERMs) tissue-selective estrogen agonist/antagonist properties Used in the tx of osteoporosis and breast cancer associated with an increased incidence of endometrial cancer and thromboembolitic disease

Answer 113

typically arise secondary to infection of the biliary tract, which results in the release of B-glucuronidase by injured hepatocytes and bacteria. The presence of this enzyme contributes to the hydrolysis of bilirubin glucuronides and increases the amount of unconjugated bilirubin in bile

Answer 114

should be obtained by the physician performing the procedure

Answer 115

hepatic artery, portal vein and common bile duct run through the hepatoduodenal ligament (portal triad) Occlusion of the portal triad (pringle maneuver) is a surgical technique used to distinguish the source of right upper quadrant bleeding. If bleeding persists, the inferior vena cava or hepatic veins are likely to be injured

Answer 116

The left kidney lies immediately deep to the tip of the 12th rib on the left

Answer 117

glucose is normally filtered at the glomerulus and completely reabsorbed by the proximal tubule Inhibition of Na-coupled, carrier-mediated transport of glucose by the proximal tubule would cause the glucose clearance to approach the value of the GFR (typically estimated with inulin)

Answer 118

Right ventricle A penetrating injury at the left sternal border in the 4th intercostal space would puncture the anterior surface of the heart

Answer 119

Characteristics of a drug such as high molecular weight, high plasma protein binding, high charge and hydrophilicity tend to trap the drug in the plasma compartment resulting in a low Vd (3-5 L)

Answer 120

part of a continuous circuit with the systemic circulation rate of blood flow through the pulmonary circulation must equal the rate of blood flow in the systemic circulation at all times arterial pressures and oxygen contents of the pulmonary and systemic arterial systems are considerably different both at rest and during exercise

Answer 121

Deficient dihydrobiopterin reductase (BH2 --> BH4) Tetrahydrobiopterin (BH4) is a cofactor used in the synthesis of tyrosine, DOPA, serotonin and nitric oxide. Initially, tyrosine is converted to DOPA by the enzyme tyrosine hydroxyls, with BH4 used as a cofactor. Next, DOPA is decarboxylated to dopamine by the enzyme DOPA decarboxylase

Answer 122

Pts with acute mitral regurg have near-normal left atrial compliance. Therefore, they tend to develop marked pulmonary hypertension and pulmonary edema Pts with chronic mitral regurg acquire an adaptive increase in LA volume and compliance. Thus, they are less prone to pulmonary hypertension/edema but are more prone to atrial fibrillation and mural thromboembolism

Answer 123

attributable to a unique form of desmosine crosslinking between four different lysine residues on four different elastin chains. This crosslinking is accomplished by the action of extracellular lysyl hydroxylase

Answer 124

causes transmural inflammation of any area of the GI tract. The involvement of all layers of the intestinal wall explain the most common complications of chorine's disease: strictures and fistula formation

Answer 125

associated with either microangiopathic hemolytic anemia or mechanical red cell destruction In pts with prosthetic valves, RBCs are exposed to excessive shear and turbulence in the circulation, causing damage from mechanical trauma

Answer 126

detrusor overactivity --> sudden, overwhelming or frequent need to empty bladder Patients with MS most commonly develop urge incontinence due to loss of central nervous system inhibition of detrusor contraction of the bladder As the disease progresses, the bladder can become atonic and dilated, leading to overflow incontinence

Answer 127

The spleen acts both a blood filter capable of removing circulating pathogens and as a major site of opsonizing antibody synthesis. Asplenic pts are prone to infections caused by encapsulated organisms such as Strep pneumo, H influenzae, and N meningitidis

Answer 128

vit B12 deficiency Neurological damage associated with B12 deficiency includes subacute, combined degeneration of the posterior and lateral spinal columns Increased serum level of methylmalonic acid is diagnostic of vit B12 deficiency

Answer 129

Statins: used for high LDL, toxicity includes hepatitis and myopathy Niacin: used for low HDL, toxicity includes cutaneous vasodilation, hyperglycemia, hyperuricemia / gout, hepatitis Fibric acid derivatives (gemfibrozil, fenofibrate): used for high TG, toxicity includes gallstones, myopathy

Answer 130

Pts with sickle cell disease (SCD) have functional asplenia as a result of multiple infarctions of the spleen, so they are more prone to infection by encapsulated organisms such as Salmonella Salmonella has a capsule called the 'Vi antigen' that protects it from opsonization and phagocytosis Staph aureus and Salmonella are common causes of osteomyelitis in pts with SCD

Answer 131

Regional airway resistance within the first 10 generations of bronchi contributes to most of the total airway resistance of the lower respiratory tract. Resistance is maximal in the 2-5th generation airways, including the segmental bronchi. In contrast, airways

Answer 132

immune mediated acute demyelinatation of the peripheral neuropathy affects young adults and is usually preceded by a febrile illness (Campylobacter jejuni) sx: ascending muscle weakness and areflexia segmental demyelination of peripheral nerves and an endoneural inflammatory infiltrate are seen on microscopy

Answer 133

primary ciliary dyskinesia situs inversus, chronic sinusitis and bronchiectasis mutations that impair the structure or function of cilia (dyenein arms)

Answer 134

analog of pyrophosphate that can chelate calcium and promote nephrotoxic renal magnesium wasting. These toxicities can result in symptomatic hypocalcemia and hypomagnesemia (seizures) Foscarnet is used to treat CMV induced retinitis in an HIV-infected pt

Answer 135

slow K+ efflux from the ventricular myocyte, prolong repolarization and prolong the refractory period

Answer 136

increase both systolic and diastolic blood pressure via stimulation of a1-adrenoreceptors in the vascular walls elevated systemic blood pressure is associated with a reflex increase in vagal tone, resulting in decreased heart rate and slower atrioventricular node conduction velocity

Answer 137

severe infection of the subcutaneous tissue and deep fascia, surgical emergency Can be due to Strep pyogenes (PYR-positive, beta-hemolytic, gram pos cocci that grows in chains)

Answer 138

confusion, agitation, tremor, tachycardia, hypertension, clonus, hyperreflexia, hyperthermia, diaphoresis Any drug that increases serotonin levels (SSRI and MAO inhibitor combinations, high doses of SSRIs) can precipitate this syndrome Tryptophan is a precursor for serotonin

Answer 139

antihistamine with anti-serotonergic properties that can be used in the treatment of the serotonin syndrome

Answer 140

due to tear of the middle meningeal artery associated with temporal bone fracture located between the bone and dura mater 'lucid interval' followed by loss of consciousness

Answer 141

glycogenolysis provides immediate energy for strenuous muscle contraction Myophosphorylase deficiency leads to a failure of glycogenolysis with clinical manifestations of decreased exercise tolerance, myoglobinuria, and muscle pain with physical activity

Answer 142

produce dextrans from glucose that aid these organisms in colonizing host surfaces such as dental enamel and heart valves ---> subacute bacterial endocarditis (in pts with preexisting valvular defects after a dentist visit - use antibiotic prophylaxis!)

Answer 143

essential for the formation and differentiation of osteoclasts over-expression of RANK receptors in hypoestrogenic states causes increased bone resorption due to increased osteoclastic activity (low estrogen --> lower bone mass)

Answer 144

most likely a pilocytic astrocytoma (cystic and solid components on imaging) or a medulloblastoma (always solid)

Answer 145

sharply demarcated salmon-colored plaques covered with loosely adherent silvery scale frequently associated with psoriatic arthritis - deforming joint disease

Answer 146

Cardiac atria: atrial natriuretic peptide thyroid gland: calcitonin pancreatic islets: islet amyloid protein (amylin) cerebrum: B-amyloid protein pituitary: prolactin Immune globulin light chains cause multi-organ amyloid deposition in primary systemic amyloidosis

Answer 147

inhibitory via dopamine production

Answer 148

linked to drugs that are metabolized by N-acetylation in the liver ex. hydralazine, procainamide genetic predisposition determines acetylator phenotype - slow --> greater risk discontinue only in pts with clinical symptoms of lupus

Answer 149

courses along the posterior aspect of the humerus with the radial nerve Midshaft fractures of the humerus risk injury to these structures supracondylar fractures are associated with injury to the brachial artery

Answer 150

predisposes to recurrent sinopulmonary and GI tract infections due to the absence of secretory IgA. It is also associated with anaphylactic response to transfused blood products due to an immune response against transfused blood products due to an immune response against transfused IgA which the pts body recognizes as foreign

Answer 151

delayed seperation of the umbilical cord, recurrent cutaneous infections without pus formation and poor wound healing

Answer 152

FFA and serum triglycerides increase insulin resistance in overweight people

Answer 153

play in parallel (social), speak in simple sentences (language), copy a circle and use utensils (fine motor) and ride a tricycle (gross motor)

Answer 154

often caused by diabetic autonomic neuropathy in type 1 diabetics, causes overflow incontinence due to inability to sense a full bladder and incomplete emptying Postvoid residual (PVR) testing with ultrasound or catheterization can confirm inadequate bladder emptying

Answer 155

In absence of normal intestinal microbial flora (ex. after antibiotics), C diff can overgrow and produce enterotoxin (toxin A) and cytotoxin (toxin B). Clinical disease resulting from C. difficile overgrowth can range from transient diarrhea to severe pseudomembranous colitis

Answer 156

transverse portion of the duodenum is entrapped between the SMA and aorta, causing symptoms of partial intestinal obstruction occurs when the aortomesenteric angle critically decreases, secondary to diminished mesenteric fat, pronounced lordosis, or surgical correction of scoliosis

Answer 157

double stranded DNA --> +RNA template --> double-stranded DNA progeny Although it is a DNA virus it replicates via reverse transcription

Answer 158

anabolic hormone that acts via a tyrosine kinase second messenger system to stimulate the synthesis of glycogen, proteins, fatty acids and nucleic acids Tyrosine kinase leads to the activation of protein phosphatase within cells, and protein phosphatase directly modulates the activity of enzymes in the metabolic pathways regulated by insulin

Answer 159

unwinds DNA at the replication fork and separates dsDNA into ssDNA during the replication process Initial separation of dsDNA at the origin of replication is facilitated by DnaA protein and strand binding proteins (SSB) proteins.

Answer 160

usually involves the distal interphalangeal joints whereas rheumatoid arthritis typically affects the metacarpophalangeal and proximal interphalangeal joints

Answer 161

Acute Interstitial pancreatitis: pancreas is grossly edematous, focal areas of fat necrosis, calcium deposition and interstitial edema are seen on light microscopy Necrotizing (hemorrhagic) pancreatitis: chalky-white areas of fat necrosis interspersed with hemorrhage are seen on macroscopic exam

Answer 162

extrapyramidal side effect of antipsychotic medication characterized by inner restlessness and an inability to sit or stand in one position. Akathisis is frequently misdiagnosed because the restlessness is misinterpreted as worsening psychotic agitation. The pts antipsychotic dose is often increased rather than decreased, exacerbating the akathisia

Answer 163

common dysrhythmia that frequently occurs in pts with no other heart disease cause: re-enterant circuit in the AV node tx: adenosine, vagal maneuvers (carotid sinus massage and valsalva - increase baroreceptor firing --> increased parasympathetic influence --> prolonged AV node refractory pd)

Answer 164

G protein-linked receptors whose actions are mediated through various secondary messenger pathways, including increased potassium efflux Binding of morphine to mu receptors results in G protein-coupled activation of potassium conductance. Potassium efflux increases and causes hyperpolarization of postsynaptic neurons effectively blocking pain transmission

Answer 165

grow as molds at 25-30C and as yeast at body temperatures (35-37C) ex. Sporothrix, Coccidioides, Histoplasma, Blastomyces, Paracoccidioides

Answer 166

reflected by increased FSH

Answer 167

useful in pts with atypical depression (mood reactivity, rejection sensitivity, increased sleep and appetite) and treatment-resistant depression phenelzine, tranylcypromine

Answer 168

extension of the hand | damage --> wrist drop

Answer 169

gives them the ability to survive osmotic stress disrupted by: penicillins, cephalosporins (ex. Cefuroxime), vanco

Answer 170

most common type is a prolactinoma, sometimes called a lactotroph adenoma (somatotrophs, which secrete GH, are the most common cell type in the normal pituitary though)

Answer 171

Elderly pts typically have age-related renal insufficiency, even in the presence of normal creatinine levels the dose of drugs that are renally cleared (like digoxin - a cardiac glycoside) should be reduced to prevent toxicity

Answer 172

hematocrit >52% in men and >48% in women RBC mass - distinguish absolute from relative normal RBC mass indicates plasma volume contraction as the cause

Answer 173

lipopeptide antibiotic with activity limited to Gram+ organisms, including MRSA causes depolarization of bacterial cellular membrane and inhibition of DNA, RNA and protein synthesis associated with increased CPK levels and an increased incidence of myopathy

Answer 174

begins with the ligand-receptor binding and Gq-protein activation leading to activation of phospholipase C (PLC). PLC then hydrolyzes phosphatidyl inositol bisphosphate and forms diacylglycerol and inositol triphosphate (IP3). Finally, IP3 activates protein kinase C via an increase in intracellular Ca++

Answer 175

Low potency: non-neuro side effects (sedation, anticholinergic effects, orthostatic hypotension) High potency: extrapypamidal symptoms (Potent =extraPyramidal) ex. acute dystonia, akathisia

Answer 176

rare but serious adverse effect of ACE inhibitor therapy most commonly involves swelling of the tongue, lips, or eyelids and pts can also experience laryngeal edema and difficulty breathing most likely due to increased bradykinin levels as a result of ACE inhibition

Answer 177

Early - flu-like symptoms, erythema chronicum migrans Second stage - AV block, Bell's palsy Chronic - chronic asymmetric large joint arthritis and encephalopathy Treat with doxycycline or penicillin-type antibiotic

Answer 178

one of the few antiviral agents that bind and inhibit DNA polymerase in herpesvirus and reverse transcriptase in HIV that does not require intracellular activation by viral or cellular kinases pyrophosphate analog

Answer 179

dry cough, pulmonary infiltrates, hilar adenopathy, non-caseating granulomas on lung biopsy, African American

Answer 180

Pulmonary hypertension develops as a result of damage to the pulmonary arterioles manifests with an accentuated pulmonary component of the second heart sound and signs of R heart failure

Answer 181

defect in DNA excisional repair increased sensitivity to UV radiation high incidence of all forms of cutaneous malignancy

Answer 182

component of the normal colonic flora, capable of growing in hypertonic saline and bile gamma-hemolytic, catalase-negative, pyrrolidonyl arylamidase-positive genitourinary instrumentation or catheterization has been associated with enterococcal endocarditis

Answer 183

After vasectomy, viable sperm remain in the portion of the vas deferens proximal to the ligation Twenty percent of pts still have viable sperm in their ejaculate after 3 months and at least 20 ejaculations

Answer 184

heart failure due to severe myocarditis (rare) mitral stenosis after ARF requires years or decades to develop

Answer 185

presents with progressive dysphagia risk factors: chronic alcohol, cigarette smoke light microscopy: squamous cells with various degrees of atypia, foci of keratinization (if well-differentiated)

Answer 186

(most commonly) relapsing-remitting central nervous system disorder characterized by recurrent episodes of demyelination and subsequent partial remyelination relative preservation of axons in acute MS plaques, with axonal degeneration seen mostly in chronic plaques Internuclear ophthalmoplegia and optic neuritis are common symptoms

Answer 187

uniformly enlarged uterus with normal appearing endometrial tissue within the myometrium menorrhagia and dysmenorrhea are common presenting sx

Answer 188

stimulate muscarinic and nicotinic cholinergic receptors (clinical presentation = DUMBELS.. liquid from everywhere) Atropine reverses the muscarinic effects but does not prevent the development of nicotinic effects such as muscle paralysis pralidoxime is the only medication that reverses both, by 'restoring' cholinesterase from its bond with these substances

Answer 189

measure of association between an exposure and an outcome OR = ad/bc

Answer 190

in a child/young adult: presents with lower-extremity claudication (pain and cramping with exercise), blood pressure discrepancy between the upper and lower extremities, and delayed or diminished femoral pulses Turner syndrome (45, XO) is associated with coarctation of the aorta in up to 10% of cases

Answer 191

antimyobacterial agent that inhibits carbohydrate polymerization, thereby preventing peptidoglycan cell wall synthesis unique adverse effect: optic neuritis, typically presents in conjunction with decreased visual acuity, central scotoma and color blindness

Answer 192

2 of the following: delusions, hallucinations, disorganized speech, grossly disorganized behavior, and negative symptoms one must be delusions, hallucinations or disorganized speech total illness duration must be at least 6 months (including prodromal and residual pds) with at least 1 month of active symptoms

Answer 193

occurs due to uncoordinated contractions of the esophagus inefficient in propelling food into the stomach may cause symptoms of dysphagia and chest pain Chest pain may mimic unstable angina (do a cardiac workup)

Answer 194

primarily secreted into the nephron by the proximal tubule some is freely filtered by the glomerulus not reabsorbed by any portion tubular fluid concentration of PAH is lowest in Bowman's space

Answer 195

para-aortic lymph nodes however, the scrotum drains to the superficial inguinal lymph nodes

Answer 196

nocturnal upper airway obstruction (manifested by snoring) and episodic nocturnal apnea associated with systemic hypertension prolonged, untreated obstructive sleep apnea can also cause pulmonary hypertension and right heart failure

Answer 197

hypersensitivity to gluten, manifests with symptoms of malabsorption (diarrhea, steatorrhea, flatulence, and symptoms of nutrient deficiencies) serologic testing for IgA anti-endomysial and anti-tissue transglutaminase antibodies for diagnosis small bowel biopsy: atrophy of villi, flattening of the mucosa and chronic inflammation of the lamina propria tx: gluten free diet

Answer 198

redistribution of the drug to other tissues throughout the body not metabolism

Answer 199

``` bupropion (antidepressant) clozapine (antipsychotic at high doses) isoniazid (anti-TB drug, if given without pyridoxine) ciprofloxacin (antibiotic) imipenem (antibiotic) ```

Answer 200

antimuscarinic agents and antihistamines with antimuscarinic action ex. meclizine, dimendyrinate, scopolamine side effects: blurry vision, dry mouth, palpitations, urinary retention, constipation

Answer 201

increased concentrations in erythrocytes enable increased oxygen delivery in the peripheral tissues in the presence of lower blood oxygen concentration b/c 2,3-BPG decreases the affinity of hemoglobin for oxygen Produced from 1,3-BPG by the enzyme bisphosphoglycerate mutase consumes energy that would otherwise have been used by the erythrocyte to produce ATP

Answer 202

inherited, autosomal dominant (CAG)n progressive dementia and choreiform movements loss of neurons in the caudate nucleus and putamen

Answer 203

The HBsAg of hepatitis B virus must coat the HDAg of hepatitis D virus before it can infect hepatocytes and multiply

Answer 204

decrease in systolic blood pressure of greater than 10 mmHg with inspiration occurs in the setting of acute cardiac tamponade, constrictive pericarditis, severe obstructive lung disease, and restrictive cardiomyopathy

Answer 205

Beta-adrenergic agonists (Gs coupled, activate adenylyl cyclase) control acute asthma exacerbations by causing bronchial smooth muscle relaxation via increased intracellular cAMP Pulsus paradoxus can occur in the setting of severe obstructive pulmonary disease such as asthma

Answer 206

Can be endogenously synthesized from tryptophan essential component of NAD (coenzyme in the metabolism of fats, carbohydrates and amino acids) and NADPH (HMP shunt) deficiency --> pellagra: dermatitis, diarrhea, and dementia

Answer 207

acquired forms can result from medical interventions or penetrating injuries increase preload and decrease afterload by routing blood directly from the arterial system to the venous system, bypassing the arterioles High output AV shunts can lead to high-output cardiac failure

Answer 208

Broad-spectrum antibiotics suppresses the normal bacterial flora of the vagina and facilitate Candida overgrowth contraceptive use, systemic corticosteroid use, diabetes mellitus, immunosuppression

Answer 209

major pathogen in burn patients Only a few specific penicillins (ticarcillin, piperacillin) and cephalosporins (ceftazidime, cefepime) have activity against it. Certain aminoglycosides, fluoroquinolones (ciprofloxacin, levofloxacin) and carbapenems (imipenem, meropenem) are also effective

Answer 210

weakness/paralysis of gluteus medius, gluteus minimus and tensor fascieae latae muscles Trendelenburg sign: pelvis tilts downward toward the contralateral side Gluteus medius gate: pts lean toward ipsilateral side when walking to help stabilize the pelvis

Answer 211

block Na+/Cl- symporters in the distal convoluted tubules, causing enhanced Na, Cl and water excretion not as efficacious as loop diuretics can cause hypercalcemia

Answer 212

virulence factor found in the peptidoglycan wall of Staphylococcus aureus that binds to the Fc portion of IgG, leading to impaired complement activation, opsonization and phagocytosis

Answer 213

With maternal blood types A and B, erythroblastosis fetalis and hemolytic disease of the newborn do not occur, as the naturally occuring antibodies (anti-A and -B) are of the IgM type and cannot cross the placenta In type O mothers, the antibodies are predominantly IgG and can cross the placenta to cause fetal hemolysis

Answer 214

cystic degeneration of the putamen as well as damage to other basal ganglia structures The putamen is located medial to the insula and lateral to the globus pallidus on coronal sections

Answer 215

Nicotinic receptors are ligand-gated ion channels that open after binding acetylcholine. This results in immediate influx of Na+ and Ca++ into the cell and an outflux of K+ from the cell

Answer 216

antiplatelet agent that works by inhibiting the platelet surface ADP receptor as efficacious as aspirin in the prevention of thromboembolic disease

Answer 217

mucopurulent cervicitis with cervical motion tenderness is a frequent indicator of PID caused by N. gonorrhoeae or Chlamydia trachomatis can potentially lead to ectopic pregnancy and infertility due to salpingitis leading to scarring of the fallopian tubes if not treated appropriately

Answer 218

Primary: amino acids linked by covalent peptide bonds Secondary: hydrogen bonds (ex. a-helix v B-sheet)

Answer 219

characterized by retinal neovascularization due to increased vascular endothermal growth factor (VEGF) levels Acute vision loss and metamorphosia (distorted lines) fundoscopy showing a grayish-green subretinal membrane and/or subretinal hemorrhage tx: smoking cessation and VGEF inhibitor (ranibizumab, bevacizumab)

Answer 220

presentations range from neonatal death to mild episodic symptoms in adulthood by preventing the conversion of pyruvate to acetyl CoA, pyruvate is shunted to lactic acid resulting in lactic acidosis Lysine and leucine are exclusively ketogenic and would not increase the blood lactate level in pts suffering from pyruvate dehydrogenase deficiency

Answer 221

occurs due to rupture of saccular (berry) aneurysm or arteriovenous malformation. Severe vasospasm 4-12 days after the initial insult is the major cause of morbidity and mortality in pts recovering from SAH Nimodipine (selective calcium channel blocker) is often prescribed to prevent this vasospasm

Answer 222

region of the sarcomere containing only myosin thick filaments part of the A band on either side of the M line where myosin thick filaments do not have any overlapping actin thin filaments

Answer 223

Greatest to least - Central nervous system, myocardium, kidney, spleen, and liver The presence of dual and/or collateral blood supply (as seen in the liver, which is supplied by the hepatic artery and portal vein) enables an organ to tolerate arterial occlusion better than those with end-arterial circulations

Answer 224

adrenal crisis! Meningococcal septicemia can cause adrenal hemorrhage leading to acute adrenal crisis (Neisseria meningitidis septicemia + adrenal hemorrhage = Waterhouse-Friderichsen syndrome)

Answer 225

most suggestive of patent ductus arteriosus (PDA) with late onset reversal of shunt flow (from L-to-R to R-to-L) Whole body cyanosis results when there is shunt reversal in pts with septal defects or tetralogy of Fallot. Coarctation of the aorta can limit lower-extremity exercise tolerance but does not cause cyanosis in children or adults

Answer 226

arises from the C3-5 segments of the spinal cord and innervates the ipsilateral hemidiaphragm Intrathoracic spread of a lung cancer may irritate the phrenic nerve, causing hiccups and diaphragmatic paralysis with dyspnea brachial plexus involvement can cause pain in the distribution of the C8, T1 and T2 nerve roots

Answer 227

esophageal hypomotility and incompetence of the lower esophageal sphincter due to atrophy and fibrous replacement of the esophageal muscles esophageal dilation causes reflux, which increases the risk of Barrett esophagus and esophageal adenocarcinoma

Answer 228

``` Calcinosis Raynaud Esophageal dysmotility Sclerodactyly Telangiectasia ```

Answer 229

rate at which it occludes the involved artery A slowly developing occlusion would allow for formation of collaterals that could prevent myocardial necrosis A thin fibrous cap, rich lipid core, and active inflammation in the atheroma would all decrease plaque stability and thus potentially promote rapid coronary occlusion via superimposed thrombosis if the plaque were to rupture

Answer 230

common chronic inflammatory skin disorder of childhood presents with pruritis and erythematous, weeping/crusted papules and plaques that occur in response to certain environmental antigens associated with other atopic diseases: allergic rhinitis, asthma

Answer 231

can produce a very tender, small (mm diameter) red-blue lesion under the nail bed originates from the modified smooth muscle cells that control thermoregulatory functions of dermal glomus bodies

Answer 232

unilateral, pulsatile or throbbing quality, associated with photophobia, phonophobia and nausea Triptans are serotonin 5-HT agonists used as abortive therapy during an acute migraine Beta blockers, antidepressants (amitriptyline, venlafaxine) and anticonvulsants (valproate, topiramate) are commonly used for migraine prophylaxis

Answer 233

Topical vitamin D analogs (calcipotriene, calcitriol, and tacalcitol) bind to the vitamin D receptor (a nuclear transcription factor) and inhibit keratinocyte proliferation and stimulate keratinocyte differentiation

Answer 234

used in patients with von Willebrand disease because it induces endothelial procoagulatory protein release (including vWF). (It has a minimal effect on the V1 vasopressin receptor). Desmopressin can also be used for the treatment of enuresis

Answer 235

(large, eccentric nucleus, cell membrane conforming to borders of neighboring cells) activated CD8+ cytotoxic T-lymphocytes. These activated T-lymphocytes function to destroy virally infected B-lymphocytes

Answer 236

patients who have a positive PPD and a negative chest x-ray (no clinical disease) Active tuberculosis is never treated with drug monotherapy due to the fast emergence of mycobacterial antibiotic resistance from rapid, selective gene mutations

Answer 237

rare type of mechanical bowel obstruction caused when a large gallstone erodes into the intestinal lumen. Pneumobilia (air in the biliary tract) is suggestive of the diagnosis

Answer 238

provides the majority of the blood supply to the femoral head and neck; injury to this vessel can cause avascular necrosis of the femoral head A femoral neck fracture can damage the blood supply to the femoral head and neck. This is most common with displaced fractures.

Answer 239

disruption of macrophage phagolysosomes by internalized silica particles. Macrophage killing of intracellular mycobacteria may be impaired as a result, causing increased susceptibility of patients with silicosis to pulmonary TB

Answer 240

pure opioid receptor antagonist used for treating opioid intoxication or overdose. Although it binds to mu, kappa and delta opioid receptors, it has the greatest affinity for mu receptors, making it an ideal agent for treating opioid intoxication. Mu receptors: physical dependence, euphoria, respiratory and cardiac depression, reduced GI motility, sedation

Answer 241

impermeable to water regardless of serum vasopressin levels. Reabsorption of electrolytes by the Na+/K+/2Cl- cotransporter occurs in the thick ascending limb and contributes to formation of the corticomedullary concentration gradient

Answer 242

commonly occurs in the setting of chronic alcoholism. It is a megaloblastic anemia that develops due to decreased synthesis of purines and thymidine. The peripheral blood smear reveals macrocytosis, ovalocytosis and neutrophils with hypersegmented nuclei.

Answer 243

Perfusion greatly increases from the apex of the lung to the base; ventilation increases slightly from the apex to the base. Therefore, the ventilation/perfusion ratio (V/Q) decreases in the lung from apex to base

Answer 244

causes meningeocephalitis in HIV (+) pts. The latex agglutination test detects the polysaccharide capsule antigen of Cryptococcus and is used for diagnosis. India ink staining of the CSF shows round or oval budding yeast. Present in soil and pigeon droppings.

Answer 245

originates from the celiac artery and gives off several branches to the stomach and pancreas (pancreatic, short gastric, and left gastroepiploic arteries) before finally reaching the spleen. Due to poor anastomoses, the gastric tissue supplied by the short gastric arteries is vulnerable to ischemic injury following splenic artery blockage.

Answer 246

most common cause of hair loss in both males and females, and demonstrates polygenic inheritance with variable penetrance. The pattern and severity of the baldness varies between males and females, and circulating androgen levels along with the degree of genetic predisposition are thought to play a prominent role in determining clinical manifestations

Answer 247

inherited deficiency of alpha-galactosidase A that causes accumulation of the globoside ceramide trihexoside in tissues. The earliest manifestations of Fabry disease are angiokeratomas (punctuate, dark red, non-blanching macules and papules that classically occur between the umbilicus and the knees), hypohidrosis and acroparesthesia (episodic, often debilitating, burning neuropathic pain in the extremities). Without enzyme replacement, patients typically develop progressive renal failure.

Answer 248

Under normal circumstances, the right ventricular thickness is between 3-4mm during diastole, significantly thinner than the left ventricular wall thickness (1 cm). RVH is a feature of cor pulmonale, a condition caused by pulmonary hypertension resulting from disease of the lung parenchyma or the pulmonary vasculature. In young females between 20-40, primary pulmonary hypertension may be responsible for cor pulmonale.

Answer 249

Ampicillin is the treatment of choice for Listeria (facultative intracellular organism). It is not sensitive to cephalosporins. Listeria causes disease in neonates and immunocompromised adults (deficiencies of cell-mediated immunity).

Answer 250

Duodenal ulcers are not associated with an increased risk of carcinoma in the same location. In contrast, esophageal, gastric, and colorectal cancers are frequently identified as ulcerative lesions on endoscopy. Ulcerative colitis is associated with increased risk of colorectal cancer

Answer 251

A bicuspid valve is a common cause of aortic stenosis in the US. The classic auscultatory finding in patients with aortic stenosis is a harsh, crescendo-decrescendo systolic ejection murmur heard best in the right second intercostal space with radiation to the carotids.

Answer 252

mid-systolic click and late systolic murmur

Answer 253

characteristic of erythema infectiosum (‘fifth disease’, parvovirus B19 infection – small, nonenveloped DNA virus). This virus is highly tropic for erythroid precursor cells and replicates predominantly in the bone marrow.

Answer 254

metastasis from another primary site (breast, lung, colon), not hepatocellular carcinoma. The liver is the second most common site of metastatic spread after lymph nodes

Answer 255

develops most commonly following aspiration and can be confused with lung abscess, malignancy, or TB. Microscopic findings include filamentous, branching, gram-positive bacteria and sulfur granules.

Answer 256

causes a sharp decrease in cardiac output due to loss of function of a zone of myocardium. On a cardiac function curve, myocardial infarction would decrease both the slope and the maximal height of the line

Answer 257

First generation Hi-histamine receptor antagonists, including diphenhydramine (Benadryl) and chlorpheniramine, can cause significant sedation, especially when used with other medications that cause CNS depression (such as benzodiasepines)

Answer 258

responsible for tetanus, a toxim-mediated disease that causes uncontrolled muscle spasms and respiratory failure. Toxin travels within the motor neuron by retrograde transport into the spinal cord where it causes inhibition of inhibitory interneurons and unregulated firing of primary motor neurons

Answer 259

controlled by the inhibitory effect of hypothalamic dopamine. Hyperprolactinemia causes hypogonadism by inhibiting the release of gonadotrophin-releasing hormone from the hypothalamus. Rispiridone and other antipsychotics cause hyperprolactinemia by their antidopaminergic action

Answer 260

The diarrhea caused by celiac disease can lead to vitamin D deficiency through malabsorption. Patients with vitamin D deficiency have decreased serum phosphorus, increased serum parathyroid hormone (secondary hyperparathyroidism), and low serum calcium. They may also have symptoms such as bone pain and muscle weakness.

Answer 261

are exposed to high maternal glucose levels in utero, resulting in excessive fetal insulin production and islet hyperplasia. Fetal hyperinsulinemia persists for several days following birth and predisposes the infant to transient hypoglycemia

Answer 262

drug of choice for treating heroine addiction and abuse. It is a very potent, long acting opiate with good oral bioavailability. Its long half-life allows for prolonged effects to suppress withdrawal symptoms in heroin dependent patients

Answer 263

chemically related to pyridoxine, also known as Vitamin B6. It inhibits mycolic acid synthesis in mycobacterial cells and is specific to the mycobacteria. Myocolic acid is a long branched chain saturated fatty acid used in the mycobacterial cell wall and in the formation of virulence factors

Answer 264

Dystrophic calcification occurs in damaged or necrotic tissue in the setting of normal calcium levels; metastatic calcification occurs in normal tissues in the setting of hypercalcemia

Answer 265

eating disorder characterized by low body weight, intense fear of becoming fat, and distorted body image. Medical complications, including bradycardia, hypotension, osteoporosis, amenorrhea, and cardiac atrophy are a result of malnutrition and starvation

Answer 266

Nephritic syndrome is manifested by hypertension, mild proteinuria (3.5g/day), lipiduria, absence of RBC casts in the urine, and usually normal renal function.

Answer 267

paraneoplastic syndrome associated with neuroblastoma. This tumor, associated with an increased number of copies of the N-myc gene, is the most common extracranial neoplasm in children. Clinical presentation: retroperitoneal mass, hypertension, anorexia, weight loss, increased excretion of catecholamines in urine

Answer 268

Constitutional symptoms, a mid-diastolic rumbling murmur heard best at the apex, positional cardiovascular symptoms (dyspnea, syncope), embolic symptoms, and a large pedunctulated mass in the left atrium Histologically, these tumors are composed of scattered cells within a mucopolysaccharide stroma, abnormal blood vessels and hemorrhaging

Answer 269

rare form of bone marrow failure characterized by severe hypoplasia of marrow erythroid elements in the setting of normal granulopoiesis and thrombopoiesis. Pure red blood cell aplasia (often involves the inhibition of erythropoietic precursors and progenitors by IgG autoantibodies or cytotoxic T lymphocytes) is associated with thymoma, lymphocytic leukemias, and parvovirus B19 infection

Answer 270

may cause reperfusion arrhythmia on arterial re-opening. These arrhythmias are usually benign. Thrombolytic or bibrinolytic drugs increase clot lysis by increasing the formation of plasmin from plasminogen. Fibrinolytic drugs can be nonfibrin specific (like streptokinase) or fibrin-specific, such as tissue plasminogen activator (tPA), and reteplase, tenecteplase (these act only on fibrin attached to recently focmed clot, no systemic activation)

Answer 271

normal inhabitants of the oral cavity and are a cause of transient bacteremia after dental procedures in healthy and diseased individuals. In order to cause subacute bacterial endocarditis they require preexisting valve damage leading to the local deposition of fibrin required for them to adhere

Answer 272

thickening and hyperpigmentation of skin in the flexural areas. The lesions have a classic ‘velvety’ texture. Acanthosis nigricans is commonly associated with insulin-resistant states (diabetes mellitus, acromegaly, obesity) and gastrointestinal malignancies.

Answer 273

leads to glycogen accumulation within lysosomal vesicles. Clinical manifestations of this disease include hepatomegaly, cardiomegaly, macroglossia, hypotonia, and mental retardation in its most severe form

Answer 274

can occur after viral gastroenteritis or other diseases that damage the intestinal epithelium. This disease causes abdominal distention, flatulence, and diarrhea after lactose ingestion (lactose = galactosyl beta-1,4-glucose)

Answer 275

derived from amino acids (Val, Ile, Met, Thr), odd numbered fatty acids and cholesterol side chains. Congenital deficiency of propionyl CoA carboxylase, the enzyme responsible for the conversion of propionyl CoA to methylmalonyl CoA, leads to the development of propionic acidemia

Answer 276

common cause of thrombocytopenia and should be suspected in patients with ecchymoses, petechiae, and mucosal bleeding without signs or symptoms of TTP/HUS, pancytopenia, marrow failure, or splenomegaly

Answer 277

Commonly used drugs such as the analgesic tramadol, the antiemetic ondansetron, and the antibiotic linezolid can induce serotonin syndrome (neuromuscular excitation, autonomic stimulation, altered mental status) when used concomitantly with other serotonergic drugs (many antidepressants)

Answer 278

occurs weeks following transplantation and is primarily a cell-mediated process. On histopathologic analysis of an endomyocardial biopsy, a dense mononuclear lymphocytic infiltrate with cardiac myocyte damage will be visualized. Treatment with immunosuppressive drugs is aimed primarily at preventing this form of rejection.

Answer 279

Anytime a pt has bitemporal hemianopsia, a pituitary tumor should be suspected. The most common functional pituitary tumor is a prolactinoma. Secreting prolactinomas inhibit the entire axis of GnRH-LH/FSH-sex hormones, causeing impotence in men and amenorrhea in women of reproductive age (hypogonadotropic amenorrhea)

Answer 280

inhibits the formation of deoxythymidine monophosphate (dTMP), which limits DNA synthesis and promotes megaloblastosis and erythroid precursor cell apoptosis. Because thymidine supplementation can moderately increase dTMP levels, it can reduce erythroid precursor cell apoptosis

Answer 281

causes cat-scratch disease, bacillary angiomatosis and culture-negative endocarditis. Cat-scratch disease is characterized by low fever, lymphadenopathy and self-limited course

Answer 282

The ureters cross over the common / external iliac vessels and under the gonadal vessels (and uterine vessels in females). They lie anterolateral to the internal iliac vessels and medial to the ovarian vessels within the true pelvis

Answer 283

suggestive of Paget disease of bone (PDB); biopsy showing a mosaic pattern of lamellar bone is diagnostic. The initial abnormality in PDB is an increase in the number and activity of osteoclasts (excessive RANK signaling and NF-kB activation), followed by increased osteoblastic activity and bony overgrowth

Answer 284

strongly associated with smoking and usually is centrally located. This tumor arises from the primitive cells of the basal layer of the bronchial epithelium. Immunohistochemical stains are frequently positive for neuroendocrine markers, such as neuron specific enolase, chromogranin and synaptophysin

Answer 285

intravenous hydration with normal saline and insulin. These therapies will result in decreases in the serum glucose, osmolality, and potassium, as well as increases in serum bicarbonate and sodium.

Answer 286

associated with a serum-sickness like syndrome (malaise, fever, skin rash, pruritis, lymphadenopathy, joint pain) in the prodromal period. ALT > AST, both elevated

Answer 287

caused by mutations that result in defective transcription, processing, and translation of beta-globin mRNA. This leads to deficiency of the beta-globin chains required for normal hemoglobin synthesis. Patients who are heterozygous for these mutations are typically asymptomatic and have what is termed beta-thalassemia minor. Laboratory tests will show a mild hypochromic microcytic anemia with increased hemoglobin F, hemoglobin A2 and target cells

Answer 288

benign disorder of fructose metabolism caused by fructokinase deficiency. In patients with essential fructosuria, some of the dietary fructose load is converted by hexokinase to fructose-6-phosphate, which can then enter glycolysis; this pathway is not significant in normal individuals

Answer 289

expressed primarily in muscle cells and adipocytes and is the major glucose transporter that is responsive to insulin

Answer 290

substitute for the action of alcohol on GABA receptors and are indicated for the treatment of alcohol withdrawal. Long acting benzodiazepines (chlordiasepoxide, diazepam) are first line medications. Short acting Benzodiazepines (lorazepam, oxazepam) are preferred in patients with advanced liver dysfunction

Answer 291

strains of H. influenza that do not form an antiphagocytic capsule. They are part of the normal flora of the upper respiratory tract, but can cause otitis media, sinusitis and bronchitis. Immunity to nontypable strains, as well as capsular strains other than type b, is not conferred by vaccination with the Hib vaccine (just memory B-lymphocytes, humoral immunity to Hib)

Answer 292

Thyroid function tests should be monitored in patients receiving amiodarone therapy (class III anti-arrhythmic agent used to suppress life threatening cardiac conduction abnormalities). Amiodarone is associated with many side effects: thyroid dysfunction, corneal micro-deposits, blue-gray skin discoloration, drug-related hepatitis and pulmonary fibrosis

Answer 293

occurs in infants and children due to the production of the exotoxin exfoliatin (EXfoliatin is an EXotoxin, not endotoxin) by Staphylococcus species. It causes widespread epidermal sloughing, especially with gentle pressure (Nikolsky’s sign)

Answer 294

occurs as a result of mutations of each of the two Rb genes (‘two hits’). These patients have an increased risk of secondary tumors, especially osteosarcomas, later in life. Dephosphorylated Rb is active and does not allow the cell to proceed from G1 to the S stage of the cell cycle

Answer 295

The left ventricle forms the apex of the heart and reaches as far as the fifth intercostal space at the left midclavicular line. All other chambers of the heart lie medial to the left midclavicular line. The lungs overlap much of the anterior surface of the heart

Answer 296

Hypothyroidism is a common cause of elevated creatinine kinase (CK) due to hypothyroid myopathy (myocyte damage and leakage of muscle enzymes). It can be the first manifestation of hypothyroidism. Other causes of elevated CK include autoimmune diseases (polymyositis, dermatomyositis), muscular hystrophies, and medications such as HMG-CoA reductase inhibitors

Answer 297

Antidepressants (such as Venlafaxine, a serotonin-norepi reuptake inhibitor) can induce mania in susceptible patients, especially those with unrecognized bipolar disorder. Patients treated with antidepressants should be monitored for mood elevation and symptoms suggestive of mania that require emergency treatment.

Answer 298

short-acting hypnotic medication chemically unrelated to benzodiazepines (such as temazepam, estazolam, triazolam, flurazepam). It has the same mechanism of action as benzodiazepines, but a much lower risk of tolerance and dependence

Answer 299

contains bacterial capsular polysaccharide conjugated with diphtheria toxoid

Answer 300

an absence of GnRH secretory neurons in the hypothalamus due to defective migration from the olfactory placode. These patients have central hypogonadism and anosmia, and present with delayed puberty

Answer 301

acts as an indirect sympathomimetic by inhibiting the presynaptic reuptake of norepinephrine, dopamine, and serotonin. Intoxicated pts develop agitation, tachycardia, hypertension, and light-responsive mydriasis due to increased sympathetic activity. Cocaine is also a potent vasoconstrictor that can cause myocardial ischemia and atrophy of the nasal mucosa and septum

Answer 302

Unlike other traditional antipsychotics, which act on D2 receptors, clozapine acts on D4 receptors. Effective in tx of treatment-resistant schizophrenia. Due to the risk of life-threatening agranulocytosis with clozapine, the FDA requires periodic monitoring of the WBC count for the duration of treatment. The other important side effect of clozapine is seizures

Answer 303

consists of a cystic cavity surrounded by a dense wall. The wall of this cyst is formed by astrocyte processes

Answer 304

serratus anterior muscle serves to fix the scapula against the posterior chest wall and rotate the scapula to allow abduction of the arm over the head. Paralysis of this muscle occurs with injury to the long thoracic nerve and results in winging of the scapula

Answer 305

Depression of the entire hypothalamus-pituitary-adrenal axis by glucocorticoid therapy is the most common cause of adrenal insufficiency. Adrenal crisis can be precipitated in these patients under stressful situations (infections, surgery) if their glucocorticoid dose is not appropriately increased

Answer 306

mimic the action of endothelial derived relaxing factor (nitric oxide, NO). They are transformed to NO at the vascular smooth muscle cell membrane which leads to increased cGMP, decreased intracellular calcium and myosin dephosphorylation (→ pain relief and decreased BP)

Answer 307

develops on chronically sun-exposed areas of the skin in predisposed individuals. The lesions consist of erythematous papules with a central scale and a rough ‘sandpaper-like’ texture. AKs are considered premalignant lesions and have the potential to progress to squamous cell carcinoma

Answer 308

manifests with proximal muscle weakness and atrophy. True hypertrophy of the distal muscle is noted early in the disease as distal muscles compensate for weak proximal ones. Later, muscle fibers of the distal extremities are replaced by fat and connective tissue (pseudohypertrophy)

Answer 309

produce aminoglycoside-modifying enzymes that transfer different chemical groups (acetyl, adenyl or phosphate) to the aminoglycoside molecule and therefore impair antibiotic binding to ribosomal subunits

Answer 310

In contrast to angina, the chest pain of pericarditis is sharp and pleuritic, and may be exacerbated by swallowing or relieved by leaning forward. Early-onset pericarditis develops in about 10-20% of patients between days 2 and 4 following a transmural myocardial infarction. It represents an inflammatory reaction to cardiac muscle necrosis that occurs in the adjacent visceral and parietal pericardium. Late-onset post-MI pericarditis (Dressler’s syndrome) begins one week to a few months following the MI, and affects less than 4% of cases. Dressler’s syndrome is thought to be an autoimmune polyserositis

Answer 311

LH stimulates the theca interna cells of the ovarian follicle to produce androgens. Aromatase within the follicle’s granulosa cells subsequently converts these androgens to estradiol under FSH stimulation. The theca externa cells serve as a connective tissue support structure for the follicle

Answer 312

characterized by fever, pharyngitis, sandpaper-like rash, circumoral pallor, and a strawberry tongue. It is caused by strains of Group A streptococcus that produce pyrogenic exotoxins. Scarlet fever can predispose to acute rheumatic fever and glomerulonephritis

Answer 313

should be suspected in all patients with premature onset (

Answer 314

Acute bacterial arthritis in sexually active young adults is commonly caused by Neisseria gonorrhoeae, which are facultative intracellular organisms often seen within neutrophils

Answer 315

results from failure of forebrain cleavage into cerebral hemispheres. It is an example of a congenital malformation, a primary abnormality in a development process.

Answer 316

Amniotic band syndrome is an example of a disruption (secondary destruction of a previously well-formed tissue or organ) Congenital hip dislocation, clubbed feet and flat facies (Potter syndrome) are examples of deformations (secondary to extrinsic compression) Potter syndrome is also an example of a sequence (number of abnormalities from a single defect – oligohydramnios, low volume of amniotic fluid)

Answer 317

Serum TSH level is the most sensitive Although TSH is not elevated in patients with central hypothyroidism, this form of hypothyroidism is uncommon and usually occurs in pts with hypothalamic or pituitary dysfunction

Answer 318

most likely represents tricuspid regurgitation tricuspid regurg is loudest near the left lower sternal border (Mitral regurg and VSD do not typically increase with inspiration)

Answer 319

probability of not having a disease given a negative test result varies based on prevalence (inversely proportional) NPV = d/(c+d)

Answer 320

Root cause analysis is a quality improvement measure that identifies what, how and why a preventable adverse outcome occurred. It involves collecting data mainly through interviewing multiple individuals involved in the steps leading to the outcome

Answer 321

Indirect inguinal hernias are located lateral to the inferior epigastric vessels. They can continue into the scrotum and are felt by deep palpation of the external inguinal ring with the tip of the finger Direct inguinal hernias are located medially to the inferior epigastric vessels. They do not protrude into the scrotum and are best felt with the pulp of the finger

Answer 322

Irritation of the mediastinal or diaphragmatic parietal pleura will cause sharp pain, worse on inspiration, in the C3-C5 distribution. Pain sensation from these areas is carried by the phrenic nerve

Answer 323

most common primary brain tumor in adults areas of necrosis and hemorrhage seen on gross exam light micrsoscopy shows pseudopalisading tumor cells around areas of necrosis

Answer 324

bronchoconstriction and increased bronchial mucus secretion (ACh acts on M3) These effects increase airway resistance and the work of breathing Anticholinergic agents such as tiotropium and ipatropium work to counteract these effects

Answer 325

failure of chromosome pairs to separate properly during cell division. This could be due to failure of homologous chromosomes to separate in meiosis I or failure of sister chromatids to separate during meiosis II or mitosis

Answer 326

characteristic of pityriasis versicolor, a condition caused by Malassezia furfur. KOH preparation of skin scrapings reveals a 'spaghetti and meatballs' appearance on light microscopy

Answer 327

caused by a defect in a-keto acid dehydrogenase, leading to an inability to degrade branched chain amino acids beyond their deaminated a-keto acid state classically results in dystonia and poor feeding as well as the 'maple syrup scent' of the pts urine within the first few days of life tx: dietary restriction of branched-chain amino acids

Answer 328

The afferent limb of the light reflex pathway is the optic nerve The efferent limb is the parasympathetic fibers of the oculomotor nerve When an optic nerve is damaged, light in that eye will cause neither pupil to constrict (the nerve can't sense the light). However, light in the contralateral eye will cause both pupils to constrict (because the motor pathways are intact)

Answer 329

inhibition of the Na-K-ATPase in cardiac pacemaker cells leading to AV nodal blockade (increased diastolic filling time for greater contraction by the Frank-Starling mechanism) and increased contractility from increased intracellular calcium

Answer 330

idiopathic hypercalciuria normal serum calcium levels with high levels of Ca++ excreted in the urine other causes of calcium nephrolithiasis include hyperoxaluria, hyperuricosuria, low urinary volume, and hypocitraturia

Answer 331

aggregated in the deoxygenated state HbS polymers form fibrous strands that reduce RBC membrane flexibility and promote sickling. Sickling occurs under all conditions associated with anoxia including low pH and high 2,3-DPG. These inflexible erythrocytes predispose to microvascular occlusion and microinfarction

Answer 332

opiate anti-diarrheal structurally related to meperidine. It binds to mu opiate receptors in the GI tract and slows motility. Low therapeutic doses allow for potent anti-diarrheal effects without euphoric effects. Since higher doses can lead to euphoria and physical dependence, the drug is combined with atropine at therapeutic doses to discourage abuse

Answer 333

helpful for secretory diarrhea

Answer 334

clonal myeloproliferative disease of pluripotent hematopoietic stem cells increased RBC mass, increased plasma volume, low erythropoietin levels majority of pts have a JAK2 V617F mutation, rendering te hematopoietic stem cells more sensitive to growth factors secondary polycythemia is a misnomer (only red cells increase, not all). Should be called secondary erythrocytosis

Answer 335

``` RA: 0-8 RV: 4-25 PA: 9-25 LA: 2-12 LV: 9-130 Aorta: 70-130 ```

Answer 336

Respiratory and gastric glands: reduces luminal Cl- secretion and increases Na+ and net water absorption, resulting in dehydrated mucus and a more negative transepithelial potential difference Sweat glandsL reduced luminal salt absorption, leading to the production of hypertonic sweat with high Cl- content

Answer 337

unenveloped, single-stranded RNA virus spread through the fecal-oral route high mortality rate observed in infected pregnant women

Answer 338

this fungus produces thin, septate hyphae with acute V-shaped branching. It causes invasive aspergillosis, aspergillomas, and allergic pulmonary aspergillosis Immunosuppressed pts are at risk

Answer 339

indicates chronic elevation of pulmonary capillary hydrostatic pressures, which is usually the result of left-sided heart failure Golden cytoplasmic granules that turn dark blue with Pussian blue staining (Prussian blue stain detects intracellular iron)

Answer 340

cause a purely toxin-mediated watery diarrhea toxins secreted by these organisms modify electrolyte handling by enterocytes but do not cause cell death, therefore no erythrocytes or leukocytes are typically noted on stool microscopy

Answer 341

block potassium efflux from cardiac myocytes and prolong phase 3 of the myocyte action potential

Answer 342

intramuscular glucagon in the nonmedical setting and intravenous dextrose in the medical setting

Answer 343

fexofenadine - minimal sedative and antimuscarinic effects | v 1st gen: hydroxyzine, promethazine, chlorpheniramine, diphenhydramine

Answer 344

Sensitized Th2 cells secrete IL-4 and IL-13, which together promote B-lymphocyte class switching for IgE synthesis. They also secrete IL-5, which activates eosinophils and promotes IgA synthesis An excess of these Th2-produced lymphokines may contribute to the pathogenesis of extrinsic allergic asthma IL-1 is secreted by macrophages to stimulate helper T-cells IL-3 from helper T-cells recruits bone marrow stem cells y-interferon from helper T-cells functions mainly to activate macrophages TGF-B is a growth factor involved in tissue regeneration and repair

Answer 345

Renal calculi occur when there is an imbalance of factors that facilitate and prevent stone formation increased concentration of calcium, phosphate, oxalate, and uric acid promotes salt crystallization, wheras increased citrate and high fluid intake help prevent calculi formation

Answer 346

relatively selective B1-adrenergic agonist that increases heart rate, contractility, conduction velocity and myocardial oxygen consumption used in the tx of acute heart failure associated with decreased myocardial contractility (cardiogenic shock)

Answer 347

ATP is the regulatory substance that stimulates KATP channel closure in insulin-producing pancreatic beta cells (closure --> depolarization --> opening of voltage gated Ca++ channels --> insulin release)

Answer 348

amino acid sequence on peptidoglycan precursor molecules that is recognized by the enzyme transpeptidase Penicillins are structural analogs of D-Ala-D-Ala that inhibit this enzyme by binding convalently to its active site. The result is failed synthesis of the bacterial peptidoglycan wall

Answer 349

anti-progestin agent that can be used to terminate early pregnancy The prosteglandin-E1 analogue (--> uterine contraction and cervical dilation), misoprostol, is available for clinical use in combination with the abortifactant, mifepristone

Answer 350

one of the most common congenital long-QT syndromes. This is an autosomal recessive condition which is accompanied by congenital neurosensory deafness. QT-interval prolongation predisposes to syncopal episodes and possible sudden cardiac death due to torsades de pointes

Answer 351

occurs in up to 25% of pts with systemic lupus erythematosus (SLE) can cause small cardiac valvular vegetations on either side of a valve, resulting in fibrotic valve thickening and deformity may cause an acute coronary syndrome at a young age even with angiographically normal coronary arteries

Answer 352

Pancreatic exocrine secretions are the major source of bicarbonate entering the duodenum Secretin is the hormone that stimulates the release of bicarbonate-rich secretions from the exocrine pancreas. Secretin is produced by S enteroendocrine cells in the duodenal mucosa in response to stimulation by intraluminal acidity. Hydrochloric acid is the most potent stimulus for secretin release

Answer 353

characteristic of type 2 diabetes mellitus A strong linkage with HLA class II gene makeup (DR3, DR4), pancreatic islet infiltratio with leukocytes (insulitis) and antibodies against islet antigens are frequently seen in type 1 diabetes

Answer 354

present at age 2-4 years with early virilization, increased linear growth, elevated levels of 17-hydroxyprogesterone and androgens Females with classic 21-hydroxylase deficiency (with or without salt-wasting) present with ambiguous genitalia at birth

Answer 355

low doses of exogenous corticosteroids to suppress excessive ACTH secretion and reduce stimulation of the adrenal cortex

Answer 356

Renal cortical cells sense hypoxia and respond by synthesizing and releasing erythropoietin. Erythropoietin stimulates the production of erythrocytes in the bone marrow

Answer 357

Classic picture of primary biliary cirrhosis (PBC) chronic liver disease characterized by autoimmune destruction of the intrahepatic bile ducts and cholestasis

Answer 358

develops due to reactivation of varicella-zoster virus in the dorsal root ganglia (sensory neurons) presents with painful vesicular rash in a dermatomal distribution Light microscopy: intranuclear inclusions in keratinocytes and multinucleated giant cells are seen

Answer 359

The onset of action of a gas anesthetic depends on its solubility in the blood (blood/gas partition coefficient). Drugs with high blood/gas partition coefficients are more soluble in the blood, demonstrate slower equilibration with the brain and have longer onset times

Answer 360

most common non-nuclear DNA found in eukaryotic cells resembles prokaryotic DNA and is maternally derived mutations involving mtDNA or nuclear DNA that codes for mitochondrial proteins can cause a variety of mitochondrial disorders, including Leigh syndrome and MELAS

Answer 361

necessary for anabolic reactions that use NADPH as an electron donor (including cholesterol and fatty acid synthesis). In addition, NADPH produced via the HMP shunt is the only method of reducing glutathione (and thus repairing oxidative damage) available to red blood cells

Answer 362

site that binds to the Fc receptors on neutrophils and macrophages. Antibody bound to antigen is able to signal for the phagocytosis of that antigen by a conformational change of the Fc region allowing binding to the Fc receptor on phagocytes. This leads to subsequent phagocytosis of the organism / antibody complex and subsequent destruction of the organism

Answer 363

most commonly silent or subclinical (‘anicteric’) in young children but can also present as an acute, self-limited illness characterized by jaundice, malaise, fatigue, anorexia, nausea, vomiting, right upper quadrant pain, or an aversion to smoking (would have anti-hep A IgG positive, current infection would be anti-HAV IgM)

Answer 364

Of the pneumoconiosis that can cause exertional dyspnea and interstitial densities on chest x-ray, silicosis is the only one that produces eggshell calcifications of hilar nodes and birefringent particles surrounded by fibrous tissue on histologic exam.

Answer 365

o Asbestosis is associated with calcified pleural plaques and ferruginous bodies. o Berryliosis and hypersensitivity pneumonitis may produce noncaseating granulomas. o Coal miner’s lung is associated with perilymphatic accumulations of coal dust-laden macrophages

Answer 366

characteristic auscultatory finding in patients with ASD. A hemodynamically significant ASD can produce chronic pulmonary hypertension as a result of left-to-right intracardiac shunting. Eisenmenger syndrome is the late-onset reversal of a left-to-right shunt due to pulmonary vascular sclerosis resulting from chronic pulmonary hypertension. Closure of the ASD may be required to prevent irreversible pulmonary vascular sclerosis and a permanent Eisenmenger syndrome

Answer 367

total sensory loss on the contralateral side of the body. Although there are no motor deficits, proprioception is often profoundly affected and may lead to difficulty ambulating and falls.

Answer 368

o Frontal cortex lesions – deficits of higher brain functioning, creativity, sexual interest, social behavior o Internal capsule – motor deficit o Pons – coma, bilateral paralysis, decerebrate rigidity, pinpoint pupils, death o Caudate nucleus – transient hemiparesis, frontal lobe symptoms (inattentiveness, forgetfulness), agitation, psychosis, choreoathetosis, dyskinesias

Answer 369

result of small vessel lipohyalinosis and atherosclerosis involving the penetrating vessels supplying the deep brain structures. Uncontrolled hypertension and diabetes mellitus are risk factors for this condition

Answer 370

Postural skeletal muscles such as the soleus and paraspinal muscles contain predominantly Type 1 slow twitch, red muscle fibers that derive ATP primarily from oxidative (aerobic) metabolism (so high myoglobin (oxygen storage) and mitochondrial (aerobic respiration) concentrations). Low level sustained force. Type II are specialized for rapid, forceful pulses of movement

Answer 371

autoimmune disease that results in a decrease in functional acetylcholine receptors on the postsynaptic terminal of the neuromuscular junction. This results in decreased ability of acetylcholine to bind and open postsynaptic cation channels, thereby decreasing the end-plate potential and preventing the formation of muscular action potentials. o Fluctuating weakness of certain voluntary muscles (particularly innervated by motor nuclei of brainstem) o Progressive weakening of muscle groups over course of day / with exercise o Decreased compound muscle action potential amplitude on EM with repeated excitation o Rapid restoration of strength of affected muscle with rest o Improvement in strength following administration of cholinesterase inhibitors o Caused by autoantibodies against postcynaptic nicotinic acetylcholine receptors

Answer 372

cholinesterase inhibitors, immunosuppressants, and possible thymectomy. Cholinesterase inhibitors may cause adverse effects related to muscarinic overstimulation, which can be ameliorated by use of an antimuscarinic agent such as scopolamine (doesn’t affect nicotinic receptors in skeletal muscle)

Answer 373

The breast milk content of vitamins D and K is typically insufficient for the nutritional needs of the newborn. Vit K is given parenterally at birth to prevent hemorrhagic disease in the newborn. Exclusively breastfed infants may develop vit D deficiency due to lack of sun exposure

Answer 374

In pts with sickle cell anemia and other chronic hemolytic disorders, the most common viral cause of an aplastic crisis is infection of erythroid progenitor cells with parvovirus B19, a non-enveloped, single-stranded DNA virus

Answer 375

specific for mitral valve prolapse (MVP). MVP is most often caused by defects in mitral valve connective tissue proteins that predispose to myxomatous degeneration. This results in stretching and elongation of the valve leaflets and chordae tendineae by chronic hemodynamic stress

Answer 376

Procollagen is synthesized within the ER as a central helical structure flanked by globular extensions. It is then transported through the golgi apparatus and released into the extracellular space, converted to tropocollagen by procollagen peptidases that remove the globular portions of the molecule. The resulting tropocollagen monomers self-assemble into collagen fibrils that are then covalently crosslinked by lysyl oxidase

Answer 377

Diabetic ketoacidosis occurs most commonly in patients with type 1 diabetes and presents with nausea and vomiting, abdominal pain, volume depletion (hypotension, tachycardia) and ketones and glucose in the urine. Regular insulin administered as an intravenous infusion is preferred for acute treatment of diabetic ketoacidosis (peaks at 2-4 hours, lasts 5-8)

Answer 378

Duodenal S-cells secrete secretin in response to increasing H+ concentrations. Secretin increases pancreatic bicarbonate secretion. The chloride content of pancreatic secretions decreases in proportion to bicarbonate concentration increases (they’re exchanged for one another at the apical surfaces of pancreatic ductal cells).

Answer 379

Clearance (CL) determines the dose rate required to maintain a steady state plasma concentration (CPss). Maintenance dose = CPss x CL / [biavailability fraction]. The bioavailability fraction is 1 if administered intravenously

Answer 380

most likely to induce violent behavior. Violence and subsequent trauma are the most common causes of death with PCP intoxication. Other lethal side effects commonly associated with drug abuse include myocardial infarction and stroke with cocaine and respiratory depression with opioids.

Answer 381

Degestive disorders such as cholestasis (characterized by the deposition of bile pigment within the hepatic parenchyma and the presence of green-brown plugs in the dilated bile canaliculi) can cause malabsorption and nutritional deficiencies of the fat-soluble vitamins. This may result in osteomalacia, which is frequently associated with vitamin D deficiency

Answer 382

nerve travels in close approximation to the inferior thyroid artery and can be injured in surgical procedures of the anterior neck (thyroidectomy), resulting in laryngeal muscle paralysis, hoarseness and dyspnea

Answer 383

can be used to treat partial and generalized seizures and works by blocking voltage-gated sodium channels. Stevens-Johnson syndrome and toxic epidermal necrolysis are rare, life-threatening adverse effects characterized by flu-like symptoms followed by widespread mucocutaneous epidermal necrosis (also associated with carbamezapine, phenobarbital and phenytoin)

Answer 384

Massive hepatic necrosis is a rare but severe complication of halothane exposure (inhalation anesthetic. It occurs due to direct liver injury by halothane metabolites and formation of autoantibodies against liver proteins. Light microscopy shows massive centrilobular hepatic necrosis.

Answer 385

caused by inhalation of spores most commonly while while working with goat hair or hides. Hemorrhagic mediastinitis evident as widened mediastinum on chest x-ray is an important clue. On microscopy it forms long chains that are described as being ‘serpentine’ or ‘medusa head’ on appearance. Bacillus anthracis produces an antiphagocytic capsule that is required for pathogenicity. The capsule is unique in that it contains D-glutamate instead of polysaccharide

Answer 386

occurs within a newly synthesized capsid through the action of reverse transcriptase on an RNA template. The mature capsid contains partially double-stranded circular DNA and reverse transcriptase

Answer 387

Anticholinergic poisoning, botulism, and organophosphate toxicity (acetylcholinesterase inhibitors) affect nicotinic and muscarinic acetylcholine receptors differently, and thus produce different symptomatologies. Muscarinic antagonists inhibit the postsynaptic action of acetylcholine, botulinum neurotoxin blocks the presynaptic exocytosis of acetylcholine vesicles, and organophosphates prevent the degradation of acetylcholine within the synaptic cleft

Answer 388

autosomal recessive disorder of bilirubin metabolism caused by a genetic lack of the UGT enzyme needed to catalyze bile glucuronidation. Unconjugated hyperbilirubinemia develops in these infants, causing kernicterus and often death

Answer 389

effectively increase calcium reabsorption from the nephron (inhibit Na/Cl cotransporter on the apical side of the distal convoluted tubule, activating basolateral Na/Ca++ antiporter, decreased Ca++ intracellular concentration enhances luminal Ca++ reabsorption) (hypovolemia induzed by thiazides → increased Na and H20 reabsorption in proximal tubule, passive increase in Ca++ paracellular reabsorption). They are indicated in pts with nephrolithiasis secondary to hypercalciuris and contraindicated in hypercalcemia

Answer 390

The first generation antihistamines, chlorpheniramine and diphenhydramine, have antimuscarinic (blurry vision), anti-alpha adrenergic (pupillary dilation, dry mouth, constipation) and serotonergic properties that are responsible for the majority of side effects

Answer 391

During hyperglycemia, excess plasma glucose is converted to sorbitol by aldose reductase. Sorbitol accumulates within some cells and attracts water into these tissues leading to osmotic cellular injury. This mechanism is implicated in the pathophysiology of cataracts and peripheral neuropathy in diabetes

Answer 392

The best treatment of chronic dry cough caused by an ACE inhibitor (like captopril) is replacement of this drug with an angiotensin receptor blocking drug (ARB), such as losartan. Remember that ARBs are also beneficial for both hypertension and diabetic neuropathy and do not interfere with the catabolism of bradykinin as ACE inhibitors do

Answer 393

most commonly transmitted through food ingestions and can cause meningitis in immunocompromised adults. Listeria is a gram positive rod with tumbling motility. It grows well in cold temperatures and can therefore contaminate refrigerated food

Answer 394

frequent cause of neonatal meningitis, second only to group B streptococci. E coli strains that cause neonatal meningitis possess the K1 capsular antigen. The K1 capsule is a virulence factor that allows the bacteria to survive in the bloodstream and establish meningeal infection Organisms that ferment lactose (e coli, klebsiella, enterobacter) cause a local drop in pH, resulting in colonies with a pink-red appearance

Answer 395

most common medical cause of excessive daytime sleepiness in the US. It occurs due to poor oropharyngeal tone and results in daytime sleepiness, morning headaches and depression

Answer 396

A component of the hepatitis B virus envelope, HBsAg is a noninfective glycoprotein that forms spheres and tubules 22nm in diameter. Infected hepatocytes may secrete enormous quantities of HBsAg, often considerably exceeding the amount of HBcAg produced

Answer 397

The hippocampus is the area of the brain demonstrating the greatest degree of atrophy in Alzheimer’s disease. Hippocampal atrophy on MRI is highly suggestive of the diagnosis

Answer 398

result of systemic hypoperfusion. The cells most susceptible to ischemia are the pyramidal cells of the hippocampus and neocortex and the Purkinje cells of the cerebellum. The hippocampus is the first area damaged during global cerebral ischemia

Answer 399

associated with celiac disease. Dermatitis herpetiformis describes groups of small vesicles that occur symmetrically on the extensor surfaces and are extremely pruritic. Immunofluorescence reveals IgA deposits in the tips of the dermal papillae

Answer 400

lacks peptidoglycan within the cell wall, and Ureaplasma urealyticum lacks a cell wall entirely. Therefore, they are not effectively treated by penicillins and cephalosporins. Antiribosomal antibiotics, like macrolides and tetracyclines, are effective against these organisms

Answer 401

Interstitial myocardial granulomas, or Aschoff bodies, are typically found in acute rheumatic carditis (preceded by group A strep pharyngitis). Aschoff bodies contain plump macrophages with abundant cytoplasm and central, round-to-ovoid nuclei with central, slender ribbons of chromatin (Anitschkow cells, ‘caterpillar cells’)

Answer 402

characterized by the triad of tinnitus, vertigo and sensorineural hearing loss. Its pathogenesis is related to increased volume and pressure of endolymph in the vestibular apparatus

Answer 403

associated with oxalate kidney stones. Impaired bile acid absorption in the terminal ileum leads to loss of bile acids in the feces with subsequent fat malabsorption. Lipids then bind calcium ions, and the resulting soap complex is excreted. Free oxalate (which is normally bound by calcium ions to form an unabsorbable complex) is absorbed and forms urinary calculi

Answer 404

deformed azurophilic granules found in the cytoplasm of myeloblasts that stain positively for myeloperoxidase. Auer rods are found in abundance in AML M3 (acute promyelocytic leukemia). The clinical manifestations of AML are anemia (fatigue, pallor), thrombocytopenia (petechiae, hemorrhages), and neutropenia (fever, opportunistic infections) and are the result of marrow replacement by leukemic cells

Answer 405

include primary amenorrhea, short stature, a high arched palate, and widely spaced nipples. Primary amenorrhea occurs in these patients due to in utero degeneration of the ovarian follicles (gonadal dysgenesis). Menstruation and breast development are estrogen-dependent processes, so they do not occur when the ovaries are nonfunctional

Answer 406

pitting edema in subcutaneous breast tissue accompanied by skin thickening around exaggerated hair follicles. The pitting edema occurs when neoplastic cells plug the dermal lymphatic channels

Answer 407

associated with GI lesions (colon cancer) in more than 25% of cases. When S. bovis is cultered in the blood, workup for colonic malignancy with colonoscopy is essential

Answer 408

Zn-containing enzymes that degrade extracellular matrix. They participate in the normal tissue remodeling and in tumor invasion through the basement membrane and connective tissue

Answer 409

Doxazosin, Prazosin and Terazosin are useful for the treatment of both benign prostatic hyperplasia and hypertension

Answer 410

o Patients with coronary artery disease and heart failure along with hypertension will benefit from cardioselective beta-blockers o Hydrochlorathiazide is presently the first line medication for the treatment of essential hypertension in the general population

Answer 411

present with identical symptoms (recurrent nightmares and flashbacks, potential memory loss, and exaggerated startle response). Acute stress disorder can last no more than 4 weeks, however, while PTSD lasts longer than 4 weeks

Answer 412

neuropeptides produced in the lateral hypothalamus that function to promote wakefulness and inhibit REM sleep-related phenomena. Most patients who have narcolepsy with cataplexy demonstrate undetectable levels of hypocretin-1 in their cerebrospinal fluid

Answer 413

consists of the triad of eczema, thrombocytopenia and combined B-lymphocyte and T-lymphocyte deficiency. Onset of disease is early in life with thrombocytopenia present at birth and eczema and repeated infections, particularly by encapsulated organisms, following at 6 to 12 months of age. Tx = HLA-matched bone marrow transplant

Answer 414

type III hypersensitivity reaction to nonhuman proteins characterized by vasculitis resulting from tissue deposition of circulating immune complexes. Clinical findings include fever, pruritic skin rash, arthralgias, and low serum C3 and C4 complement levels (7-14 days after exposure to antigen)

Answer 415

The combination of acute-onset dyspnea, calf swelling, obesity, and history of prolonged immobility is strongly suggestive of pulmonary embolism (PE). PE is most often associated with hypoxemia and respiratory alkalosis

Answer 416

Lesions of the glossopharyngeal nerve result in loss of the gag reflex (afferent limb), loss of sensation in the upper pharynx, posterior tongue, tonsils, and middle ear cavity, and loss of taste sensation on the posterior one-third of the tongue o Taste sensation from the anterior 2/3 of the tongue is mediated by the chorda tympani branch of the facial nerve (CN VII) o Protrusion of the tongue is mediated by motor efferent fibers carried by the hypoglossal nerve (CN XII)

Answer 417

Treatment with many hypolipidemic drugs (especially statins – first line therapy for pts with hypercholesterolemia, structural analogs to HMG-CoA → competitively inhibit HMG-CoA reductase, the enzyme responsible for the rate-limiting step in cholesterol synthesis) warrants monitoring of liver function tests. Statins are known to cause myopathy and liver toxicity in some pts.

Answer 418

occurs from day 15 through day 28 of the normal menstrual cycle (between ovulation and the onset of menses). Progesterone released by the corpus luteum causes the uterine glands to coil and secrete glycogen-rich mucus. The endometrial stroma becomes edematous and completely traversed by tortuous spiral arteries that extend from the deeper layers to the uterine lumen o The proliferative phase (menstruation – ovulation) shows compact, non-edematous stroma, relatively straight uterine glands

Answer 419

High circulating levels of estrogen and progesterone prevent lactogenesis while promoting breast growth and development during pregnancy

Answer 420

- Aberrant serine and threonine residue phosphorylation by serine kinase leads to insulin resistance (inhibit IRS-1 tyrosine phosphorylation by insulin). These aberrant phophorylations can occur in the presence of TNF-a, catecholamines, glucocorticoids, and glucagon.

Answer 421

Vitamin A overdose can result in intracranial hypertension (papilledema), skin changes and hepatosplenomegaly

Answer 422

o Thiamine deficiency: beriberi, Wernicke-Korsakoff o Niacin deficiency – pellagra (dementia, dermatitis, diarrhea) o B12 cobalamin deficiency – pernicious anemia o B2 riboflavin deficiency – cheilosis, stomatosis, glossitis, dermatitis o Vit E overdose – hemorrhagic strokes, necrotizing enterocolitis

Answer 423

Metformin (most common prescription for DM type 2, elevates lactate levels) is absolutely contraindicated in patients with renal failure (high serum creatinine), due to a risk of lactic accumulation. In fact, metformin is contraindicated in any situation that might precipitate lactic acidosis, such as liver dysfunction, congestive heart failure, alcoholism and sepsis

Answer 424

Receptors for cortisol are located within the cytoplasm and are translocated to the nucleus after binding to cortisol. In the nucleus, the cortisol-receptor complex binds to the hormone responsive elements, causing an alteration in the transcription of target genes. Cortisol increases the transcription of enzymes involved in gluconeogenesis (formation of glucose from fat and protein substrate)

Answer 425

characterized by a defect in hepatic excretion of bilirubin glucuronides across the canalicular membrane. Benign condition with conjugated chronic hyperbilirubinemia. Grossly, the liver is strikingly black. Histological features are normal, though a dense pigment composed of epinephrine metabolites within the lysosomes can be seen

Answer 426

often results in bile precipitation and the formation of biliary sludge

Answer 427

infection begins following skin penetration by filariform (infectious) larva and can be diagnosed by finding rhabditiform (noninfectious) larvae in the stool. Rhabditiform larvae can mature into filariform larva in the human gastrointestinal tract, precipitating an autoinfection cycle that occurs entirely within the affected individual. This can result in hyperinfection syndrome characterized by massive dissemination of the organism, leading to multiorgan dysfunction and septic shock.

Answer 428

o Shistosoma mansoni – parasite eggs in stool o Enterobius vermicularis (pinworms) – eggs on scotch tape around perianal region o Intestinal tapeworms (T solium, T saginata, D latum) – proglottids o Giardia lamblia, E histolytica – Trophosoites and cysts

Answer 429

most often a fourth heart sound (S4). An abnormal S4 can be heard in patients with reduced ventricular compliance (e.g. hypertensive heart disease, aortic stenosis, hypertrophic cardiomyopathy). It is caused by a sudden rise in end-diastolic pressure following atrial contraction. Best heard with the pt in the left lateral decubitus position, intensifies during expiration due to increased blood flow from lungs to left atrium

Answer 430

identifies organisms that have mycolic acid present in their cell walls, including Myobacterium and some Nocardia species. Acid-fast staining is carried out by applying an aniline dye (eg carbofuchsin) to a smear and then decolarizing with acid alcohol to reveal whether the organisms present are ‘acid fast’

Answer 431

Neisseria organisms can be isolated by culture on selective media such as the Thayer-Martin VCN medium, which inhibits the growth of contaminants such as Gram positive organisms, Gram negative organisms other than Neisseria, and fungi

Answer 432

All organisms in the Mycoplasma genus, including Ureaplasma, lack peptidoglycan cell walls and are therefore resistant to agents that attack the peptidoglycan cell wall such as penicillins, cephalosporins, carbapenems and vancomycin. Mycoplasma infections can be treated with anti-ribosomal agents like tetracycline and erythromycin

Answer 433

autoimmune bullous disease characterized by autoantibodies directed against desmosomal proteins 3 and 1 (painful, flaccid bullae with erosions of the skin and mucosal membranes). Bullous pemphigoid is characterized by autoantibodies against hemidesmosomal proteins (bullae usually remain intact and mucosal involvement is uncommon)

Answer 434

Phenytoin, carbamazepine and valproic acid inhibits neuronal high-frequency firing by reducing the ability of sodium (Na+) channels to recover from inactivation

Answer 435

can cause night blindness. Vitamin A deficiency may result from any cause of fat soluble vitamin malabsorption, including chronic cholestasis from biliary obstruction

Answer 436

second-line agent for treating acute gouty arthritis (NSAIDs are mainstay treatment, but contraindicated in pts with renal failure or peptic ulcer disease). It inhibits tubulin polymerization and microtubule formation in leukocytes, reducing neutrophil chemotaxis and emigration to sites inflamed by tissue deposition of monosodium urate crystals. Gastrointestinal mucosal function is also impaired by microtubule disruption, leading to diarrhea and, less commonly, nausea, vomiting and abdominal pain

Answer 437

increases serum glucose by increasing hepatic glycogenolysis and gluconeogenesis. Glucagon also stimulates insulin secretion from the pancreas. Unlike epinephrine, glucagon has an insignificant effect on glucose homeostasis in the skeletal muscle, adipose tissue and renal cortex

Answer 438

may have karyotype 45,X (complete monosomy), 45,X/46,XX (mosaicism), or 46,XX (with partial deletion of one chromosome X). The complete or partial loss on an X chromosome usually results from paternal meiotic nondisjunction. Meiotic nondisjunction is also responsible for Klinefelter syndrome and trisomies 13, 18 and 21

Answer 439

Ornithine transport into mitochondria is essential for urea formation, as ornithine is needed to combine with caramoyl phosphate within the mitochondria to form citrulline in the second step of the urea cycle. Urea cycle defects cause neurologic damage primarily due to the accumulation of ammonia. Protein restriction would improve this condition (usually, high protein diet, digested into amino acids, deamination converts nitrogen from the aa into ammonia → increase in urea excretion)

Answer 440

Hemolytic anemia is a possible side effect of dapsone (second line tx for pneumocystic jiroveci pneumonia prophylaxis in HIV pts) and is most significant in patients deficient for glucose-6-phosphate dehydrogenase (G6PD). G6PD deficiency anemia is characterized by episodes of hemolytic anemia precipitated by oxidative stress (drugs, infections, fava beans, diabetic ketoacidosis). Peripheral smear typically shows bite cells (oxidant induced damage, result of phagocytic removal of Heinz bodies) and Heinz bodies

Answer 441

(HIT) is treated with direct thrombin inhibitors (DTIs) such as argatroban. Both high molecular weight heparin and LMWH should be avoided in these pts

Answer 442

is the tendon of the supraspinatus muscle (prone to repeated impingement trauma between the humeral head and the acromion). Because the supraspinatus is an abductor of the humerus, injury to its tendon causes pain on abduction of the arm

Answer 443

High altitude exposure lasting more than a few days results in hypoxemia with a chronic respiratory alkalosis (PaO2 declines, hypoxemia stimulates chemoreceotors which increase ventilator drive, hyperventilation). The corresponding decrease in serum bicarbonate levels reflects renal compensation

Answer 444

involves an excess of non-ceruloplasmin-bound serum copper, leading to injurious accumulation of this element in the liver, CNS lenticular nucleus, and cornea. Chelation therapy with penicillamine is indicated to remove excess loosely bound serum copper

Answer 445

o Dimercaprol and EDTA are chelating agents used to treat lead poisoning o Deferoxamine is an iron-chelating agent used to treat hemochromatosis

Answer 446

Sickle cell disease is characterized by repeated splenic infarctions that ultimately result in splenic atrophy or asplenia, which is typically completed by young adulthood. After autosplenectomy, patients are predisposed to infections with encapsulated bacterial organisms

Answer 447

Patients with chronic hemolytic anemia (like sickle cell disease) are predisposed to folic acid deficiency and macrocytic changes due to increased erythrocyte turnover

Answer 448

common age-related condition that causes urinary symptoms and can be medically treated with a-adrenergic blockers (relax smooth muscle in the bladder neck) or 5-a-reductase inhibitors (reduce hormonal influence on the prostate by preventing conversion of testosterone to DHT). The prostate is located between the pubic symphysis and the anal canal in inferior sections of the pelvis on CT scan

Answer 449

Hyperplastic arteriosclerosis in renal arterioles can result from and perpetuate malignant hypertension. The pathological lesion is an onion-like concentric thickening of the arteriolar walls in the renal vasculature and elsewhere

Answer 450

caused by poor signal transmission at the neuromuscular junction. Lambert-Eaton syndrome is associated with underlying malignancy. Antibodies to voltage-gated presynaptic calcium channels are found in these pts o Myasthenia Gravis: weakness is worse at the end of the day or with exertion, extraocular muscles affected first (ptosis, diplopia), risk of thymoma, antibodies against acetylcholine receptors, improvement or resolution of weakness with tensilon test (edrophonium), decremental response to nerve stimulation o Lambert-Eaton syndrome: weakness improves during the day and with exercise. Weakness of proximal muscles. Pre-existing malignancy associated, antibodies against pre-synaptic calcium channels, no clinical improvement with tensilon test, incremental response to nerve stimulation studies

Answer 451

Patients with primary mineralocorticoid excess (hyperaldosteronism) have hypertension, hypokalemia, metabolic alkalosis, and low renin levels (question 609790)

Answer 452

Epinephrine increases the systolic blood pressure (a1 + B1), increases heart rate (B1), and either increases or decreases diastolic blood pressure depending on the dose (either a1 or B2 predominates – B2 decreases through vasodilation, predominates at low dose). Pretreatment with propranolol eliminates the B effects of epinephrine (vasodilation and tachycardia), leaving only the a effect (vasoconstriction)

Answer 453

affected males will always produce unaffected sons and carrier daughters carrier females have a 50% chance of producing affected sons and carrier daughters G6PD deficiency follows this inheritance pattern and causes acute hemolytic anemia in response to oxidant drugs

Answer 454

exits the skull through the foramen ovale and innervates the muscles of mastication, including the masseter, the medial and lateral pterygoids, and the temporalis muscles [ CN V2, maxillary, exits via the foramen rotundum; the jugular foramen contains CN IX, X, XI]

Answer 455

work by blocking angiotensin II type 1 receptors, inhibiting the effects of angiotensin II. This results in arterial vasodilation and decreased aldosterone secretion. The resulting fall in blood pressure increases renin, angiotensin 1 and angiotensin II levels. ARBs do not affect the activity of angiotensin-conversting enzyme, and therefore they do not affect bradykinin degradation and do not cause cough

Answer 456

phase 0 depolarization is mediated by an inward influx of calcium differs from phase 0 of cardiomyocytes and purkinje cells, which result from inward Na current

Answer 457

cause of pharyngoconjuctival fever that classically occurs in small outbreaks among individuals living together in close quarters (such as military barracks or camp dormitories

Answer 458

skin and mucous membranes, flesh colored pruritic papules with an umbilicated center that typically contains white, curdlike material (anogenital area + trunk)

Answer 459

innervates the flexors of the lower leg, the extrinsic digital flexors of the toes and the skin of the sole of the foot (plantar sensation) injury to the tibial nerve: foot is dorsiflexed and everted

Answer 460

indicated when an emergency airway is required and orotracheal or nasotracheal intubation is either unsuccessful or contraindicated The cricothyrotomy incision passes through the superficial cervical fascia, pretracheal fascia, and the cricothyroid membrane

Answer 461

Parietal cells release hydrogen ions into the gastric lumen by means of the H/K ATPase, which requires hydrolysis of ATP and is therefore an active transport mechanism. Omeprazole and other proton pump inhibitors suppress the activity of the gastric parietal cell H/K ATPase leading to an increase in the pH of the gastric lumen

Answer 462

found in cystic medial degeneration (characterized by the fragmentation of elastic tissue), which predisposes to the development of aortic dissections and aortic aneurysms. Medial degeneration is frequently seen in younger individuals with Marfan syndrome

Answer 463

The action potential of pacemaker cells includes phases 0, 3, and 4. Phase 4 consists of spontaneous depolarization and occurs due to the closure of K+ channels, the slow influx of Na+, and the opening of T- and L-type Ca++ channels. Acetylcholine and adenosine reduce the rate of spontaneous depolarization in cardiac pacemaker cells

Answer 464

DIC is a common complication associated with sepsis, particularly in gram negative infections: Patients bleed, coagulation cascade activated, PT and PTT prolonged, low fibrinogen and increased FDP TTP-HUS usually do not bleed, only platelets are activated, normal PT and PTT, normal fibrinogen

Answer 465

causes hereditary fructose intolerance this disease manifests after indroduction of fructose into the diet with vomiting and hypoglycemia about 20-30 minutes after fructose ingestion. These infants can present with failure to thrive, jaundice and hepatomegaly

Answer 466

intracellular signaling pathway important for anti-apoptosis, cellular proliferation, and angiogenesis mutations in growth factor receptors, Akt, mTOR or PTEN that enhance the activity of this pathway contribute to cancer pathogenesis

Answer 467

DNA-dependent RNA polymerase that incorporates short RNA primers into replicating DNA

Answer 468

manifests months to years after transplantation and presents with worsening hypertension and a slowly progressive rise in serum creatinine mediated by a chronic, indirect immune response against donor alloantigens and results in obliterative intimal thickening, tubular atrophy, and interstitial fibrosis

Answer 469

most often caused by gallstones obstructing the cystic duct. The diagnosis can be made by identifying signs of gallbladder inflammation (wall thickening, pericholecystic fluid) on ultrasonography. When ultrasound is inconclusive, nuclear medicine hepatobiliary scanning (cholescintigraphy) can be used to assess cystic duct patency and make the diagnosis (if there's an obstruction the gallbladder will not be visualized)

Answer 470

non-steroid anti-androgen that competes with testosterone and DHT for testosterone receptors used for treatment of prostate cancer in combination with GnRH agonists

Answer 471

Acute hemodynamic changes can produce functional heart murmurs, in the absence of any fixed valve lesion. Dilation of the left ventricle in response to increased preload can result in functional mitral regurgitation, which can be eliminated by preload reduction and reduced afterload reduction

Answer 472

Depending on the age and the condition of the host and species of Shigella, as few as 10-500 cells can cause infection Other organisms that need a small inoculum: Campylobacter jejuni, Entamoeba histolytica, and Giardia lamblia

Answer 473

non-motile, non-lactose fermenting organism that does not produce H2S when grown on triple sugar iron agar Mucosal invasion of the M cells that overlie Peyer's patches is an essential pathogenic mechanism for Shigella infection. Shigella then escapes the phagosome and spreads laterally to other epithelial cells via actin polymerization

Answer 474

Cough, Coryza, Conjunctivitis, and Koplic spots are diagnostic of measles (rubeola) infection Koplik spots are tiny white or blue-gray lesions on the buccal mucosa that precede the maculopapular skin rash

Answer 475

Incidental chest c-ray finding of fibrocalcific parietal pleural plaques (pleural thickening with calcification) in the posterolateral mid-lung zones and over the diaphragm

Answer 476

Alcoholics are more likely than the general population to develop pulmonary infections and abscesses involving combinations of anaerobic oral flora (Bacterioides, Prevotella, Fusobacterium and Peptostreptococcus) and aerobic bacteria. Clindamycin covers most of these organisms and is thus the antibiotic of choice for treating lung abscesses

Answer 477

mast cell stabilizing agents Inhibit mast cell drgranulation independent of stimuli present less effective than inhaled glucocorticoids, considered 2nd line tx for allergic rhinitis and bronchial asthma

Answer 478

Ovary - simple cuboidal (associated with serous, mucinous, endometrioid, clear cell and brenner tumors) Fallopian tube - simple columnar Uterus - simple (pseudostratified) columnar Cervix - simple columnar (endocervix), stratified squamous (ectocervix) Vagina - stratified squamous non-keratinized

Answer 479

behavioral and personality changes, secondary to impairment of the organizational, restraint, and motivational systems Frontal lobe syndrome can manifest in variable ways, but can often be categorized into disorganized, disinhibited and apathetic types

Answer 480

During a water deprivation test, most pts with primary polydipsia will demonstrate a significant increase in urine osmolality. Additionally, pts with primary polydipsia will have low serum sodium levels and osmolality. Restriction of water intake normalizes urine output in pts with primary polydipsia

Answer 481

As a selective estrogen receptor modulator (SERM), raloxifene binds to estrogen receptors and exhibits tissue-specific behavior that either imitates or antagonizes the effects of natural estrogen. In bone, the estrogen agonist effects of raloxifene predominate and osteoporosis is inhibited. In mammary tissue, the estrogen antagonist effects of raloxifene predominate and protection is provided against estrogen receptor-positive breast cancer

Answer 482

5-HT3 receptor antagonists are useful for the treatment of visceral nausea due to gastrointestinal insults, such as gastroeinteritis, chemotherapy, and general anesthesia Antihistamines and anticholinergics are recommended for vestibular nausea Dopamine antagonists are useful for nausea associated with migraines

Answer 483

Gingival hyperplasia is a common side effect of phenytoin and is sometimes reversible when phenytoin is withdrawn. Phenytoin causes increased expression of platelet-derived growth factor (PDGF). When gingival macrophages are exposed to increased amounts of PDGF, they stimulate proliferation of gingival cells and alveolar bone. Phenytoin toxicity mainly affects the cerebellum and vestibular system, causing ataxia and nystagmus

Answer 484

--> flushed skin and mydriasis Medications with anti-muscarinic effects: atropine, tricyclic antidepressants (amitriptyline), H1 receptor antagonists (diphenhydramine), neuroleptics, and antiparkinsonian drugs

Answer 485

most common form of congenital adrenal hyperplasia affected female infants present at birth with ambiguous (virilized) genitalia male infants have normal genitalia and present later with salt-wasting or precocious puberty high serum level of 17-hydroxyprogesterone is diagnostic

Answer 486

protein hormone produced by adipocytes in proportion to the quantity of fat stored. Leptin acts on the arcuate nucleus of the hypothalamus to inhibit production of neuropeptide Y (decreasing appetite) and stimulate production of alpha-MSH (increasing satiety). Mutations in the leptin gene or receptor result in hyperphagia and profound obesity

Answer 487

common in hospitalized pts Large emboli lodge in the pulmonary artery bifurcation. Smaller emboli occlude the peripheral branches of the pulmonary artery, producing wedge-shaped, red 'hemorrhagic' infarcts. This condition is precipitated by hypercoagulability and can be prevented by the anticoagulant heparin

Answer 488

Combined use of non-dihydropyridine calcium channel blockers (verapamil, diltiazem) and B-adrenergic blockers (atenolol) can have additive negative chronotropic effects yielding severe bradycardia and hypotension

Answer 489

The finding of a high peak in the gamma-globulin region on serum protein electrophoresis (SPEP) usually represents an M protein consisting of an overproduced monoclonal immunoglobulin. Multiple myeloma causes an M protein peak on SPEP as well as anemia (weakness), lytic bone lesions (back pain, pathologic fractures), and renal insufficiency (related to amyloid deposition and hypercalcemia)

Answer 490

results from defective dibasic amino acid transport in intestinal and proximal renal tubular epithelium cells. It most often presents with recurrent stone formation at a young age due to decreased reabsorption of cysteine from the urine. Urinalysis shows pathognomonic hexagonal cystine crystals, and the sodium cyanide-nitroprusside test can be used to detect excess cystine in the urine

Answer 491

may lead to osmotic demyelination of the axons in the central part of the pons. This condition is called central pontine myelinolysis. It manifests with spastic quadriplegia and pseudobulbar palsy

Answer 492

Asthma develops due to the interaction of genetic and environmental factors Pts are born with a genetic predisposition to have an imbalance between Th1 and Th2 lymphocytes. Environmental irritants, such as smoking, trigger bronchospasm in predisposed individuals

Answer 493

Sickle cell pts become functionally asplenic, and thus are at an especially increased risk for infection by encapsulated organisms (Streptococcus pneumoniae and Hemophilus influenza). Salmonella is the most common cause of osteomyelitis in children with sickle cell disease; Staphylococcus aureus and Escherichia coli are the next most common causes of osteomyelitis in these pts

Answer 494

The diagnosis of AML requires >20% myeloblasts in the peripheral blood or marrow. The finding of Auer rods, linear, purple-red inclusions within immature myeloid precursors, is helpful in making the diagnosis. Auer rods are not found in ALL. In CML, there are more mature cells and fewer blasts (

Answer 495

cerebellar ataxia (spinocerebellar tract degeneration), loss of position and vibration sensation, kyphoscoliosis, and hypertrophic cardiomyopathy. Foot abnormalities and diabetes mellitus are also common

Answer 496

cause of secondary hypertension in 2-5% of hypertensive pts the kidney affected by the stenosis may become atrophied due to oxygen and nutrient deprivation histology: crowded glomeruli, tubulointerstitial atrophy and fibrosis, focal inflammatory infiltrates

Answer 497

site of ribosomal subunit maturation and assembly RNA polymerase I synthesizes the vast majority of rRNA from within the nucleolus

Answer 498

systemic version of a local allergic response systemic vasodilation and increased vascular permeability as well as airway constriction are mediated by agents such as histamine, heparin and other vasoactive peptides released from mast cells and basophils after cross-linking of at least 2 molecules of surface IgE delivers the signal for degranulation

Answer 499

risk for developing asbestosis, pleural disease, and malignancies such as bronchogenic carcinoma and mesothelioma. Bronchogenic carcinoma is the most common malignancy in this population, followed by mesothelioma

Answer 500

binds the ergosterol of fungal cell membranes to exert its antifungal effects howerver, it also binds cholesterol to some degree, causing toxicity to human tissues the most important adverse effects of ampho B are nephrotoxicity, hypokalemia and hypomagnesemia

Answer 501

Due to gravity, supine pts typically aspirate into the posterior segments of the upper lobes and superior segments of the lower lobes Pts who are upright (semi-recumbent) tend to aspirate into the basilar segments of the lower lobes Aspirated material is more likely to travel down the right main bronchus

Answer 502

The green discoloration of pus or sputum noted during bacterial infections is associated with the release of myeloperoxidase (MPO) from neutrophil azurophilic granules. MPO is a heme-containing pigmented molecule

Answer 503

The development of respiratory distress, diffuse neurological impairment (confusion) and an upper body petechial rash (due to thrombocytopenia) within days of severe long bone fractures is characteristic of the fat embolism syndrome. The multiple fat emboli occluding the pulmonary microvasculature stain black with osmium tetroxide

Answer 504

seizures are the major cause of morbidity and mortality from throphylline intoxication tachyarrhythmias are the other major concern

Answer 505

Universal prenatal screening for group B strep colonization by vaginal-rectal culture at 35-37 weeks gestation is recommended to identify colonized women who require INTRAPARTUM antibiotics, most frequently with penicillin or ampicillin, to prevent neonatal GBS sepsis, pneumonia and meningitis

Answer 506

rapidly progressing fever, severe sore throat, drooling and progressive airway obstruction potentially accompanied by stridor are the presenting symptoms of acute epiglottitis. This illness is most commonly caused by H. influenzae type b, but the Hib vaccine has dropped the incidence of this disease considerably. H. influenzae type b can still cause disease in unimmunized or improperly immunized pts as well as fully immunized pts in some cases

Answer 507

can be asymptomatic or can cause pulmonary disease ranging from a flu-like illness to chronic pneumonia causes disseminated disease in immunocompromised patients spherules containing endospores are found in tissue samples

Answer 508

inhibits the initiation of protein synthesis by binding to and distorting the structure of the prokaryotic 30S ribosomal subunit

Answer 509

Exercising muscles can receive up to 85% of the total cardiac output during periods of strenuous activity thanks to local release of vasodilatory factors. Although sympathetic discharge during exercise causes an increase in cardiac output and increased contraction of blood vessels, there is only a modest blood pressure increase because the vasodilatation within muscles so significantly decreases the total systemic vascular resistance

Answer 510

endothelial injury, venous stasis, hypercoagulable state Pathophysiologically, deep venous thrombosis arises due to these factors

Answer 511

number of pts that need to be treated with a medication to avoid a negative outcome in the patient NNT is calculated by dividing 1 by the absolute risk reduction (event rate in the control group - event rate in the treatment group) Lower NNT values represent more beneficial treatments

Answer 512

In pts with HF, compensatory activation of the renin-angiotensin-aldosterone pathway and sympathetic nervous system results in increased afterload (from excessive vasoconstriction), excess fluid retention, and deleterious cardiac remodeling

Answer 513

stimulates cardiac B1 adrenoreceptors, which utilize the cAMP signal transduction pathway stimulation of these receptors by norepinephrine causes increases in cAMP concentration within cardiac myocytes NE also acts on a1 (increases IP3, peripheral vasoconstriction), a2 (decreases cAMP, decreased release of norepinephrine and insulin) B2 adrenoreceptors increase cAMP --> bronchodilatation, vasodilatation

Answer 514

short-acting balanced venous and arterial vasodilator that decreases both preload and afterload (hypertensive heart failure tx) since these changes are balanced, stroke volume is maintained

Answer 515

Patients with CF produce eccrine sweat that contains high concentrations of sodium and chloride compared to normal individuals can lead to hypovolemia due to excessive sodium loss and intravascular volume contraction

Answer 516

release of platelet-derived growth factor (PDGF) by locally adherent platelets, endothelial cells, and macrophages promotes the migration of smooth muscle cells from the media into the intima and their subsequent proliferation

Answer 517

The first peak is the 'a' wave, which is generated by atrial contraction [This is notably absent in pts with atrial fibrillation] c wave - bulging of the tricuspid into the R atrium v wave - passive increase in pressure and volume of the R atrium as it fills x-descent - relaxation of the R atrium y-descent - decrease in R atrial pressure after the tricuspid valve opens

Answer 518

Calcification and thickening of the pericardium >4mm are common features of constrictive pericarditis on CT Clinical findings include slowly progressive dyspnea, peripheral edema and ascites can be caused by TB

Answer 519

In a pt with mitral regurgitation (MR), the most reliable auscultatory finding indicating a high regurgitant volume (severe MR) and left ventricular volume overload is a left-sided S3 gallop. The intensity of the holosystolic murmur does not correlate well with regurgitant volume as larger regurgitant orifices often present with softer murmurs

Answer 520

In pts with TOF, the degree of RV outflow tract obstruction is the major determinant of the degree of R-to-L intracardiac shunting, and thus of hypoxemic symptom severity

Answer 521

The cutaneous flushing associated with niacin is mediated by prostaglandins and can be prevented with aspirin pre-treatment Capsaicin reduces pain by decreasing the level of substance P in the peripheral nervous system

Answer 522

Cough dry, nonproductive, persistent mechanism: accumulation of bradykinin, substance P or prostaglandins ARBs do not affect ACE activity, and so do not cause cough

Answer 523

2,3-bisphosphoglycerate (2,3-BPG) normally forms ionic bonds with the beta subunits of deoxygenated hemoglobin A, facilitating oxygen release in the peripheral tissues. Mutations that result in loss of the 2,3-BPG binding pocket's positive charge cause hemoglobin A to resemble fetal hemoglobin, which binds oxygen with a higher affinity due to its inability to interact with 2,3-BPG

Answer 524

The internal laryngeal nerve mediates the afferent limb of the cough reflex above the vocal cords foreign bodies (ex. fish bones) can become lodged in the piriform recess and may cause damage to the nerve, impairing the cough reflex

Answer 525

partial agonist of nicotinic acetylcholine receptors can assist pts with cessation of tobacco by reducing withdrawal cravings and attenuating the rewarding effects of nicotine

Answer 526

prophylaxis for persons who have been exposed to N. meningitidis can eliminate the carrier state as well as prevent active infection in those who have been exposed also used as a component of multi-agent therapy for both typical and atypical myobacterial pulmonary infections, leprosy and staph endocarditis when used alone, bacteria rapidly acquire resistance to rifampin through spontaneous genetic mutations of the bacterial DNA-dependent RNA polymerase

Answer 527

Alveolar hypoventilation, ventilation-perfusion mismatch, diffusion impairment, and right-to-left shunting The A-a gradient is normal with alveolar hypoventilation and helps to distinguish it from the other forms of hypoxemia

Answer 528

both beta-adrenergic blocking properties and class 3 antiarrhythmic (K+ channel blocking) properties prolongs the PR interval and the QT interval

Answer 529

Streptokinase is a thrombolytic agent that acts by converting plasminogen into plasmin, which subsequently degrades fibrin most common side effect is hemorrhage streptokinase is a foreign protein derived from Streptococci and can induce hypersensitivity reactions

Answer 530

can cause Horner syndrome (ipsilateral miosis, ptosis, anhidrosis), SVC syndrome, arm weakness, arm paresthesias and hoarseness

Answer 531

due to Aspergillus fumigatus may complicate asthma ABPA can result in transient recurrent pulmonary infiltrates and eventual proximal bronchiectasis

Answer 532

In a transplant pt, pneumonia with intranuclear cytoplasmic inclusion bodies histologically points to opportunistic infection with cytomegalovirus, an enveloped virus that contains a double-stranded DNA genome

Answer 533

hypercalcemia secondary to high levels of active vitamin D (calcitriol)

Answer 534

inhibits protein synthesis by inactivating the 30S (small) ribosomal subunit

Answer 535

decreased activity of bacterial catalase-peroxidase is one mechanism of myobacterial resistance to isoniazid

Answer 536

structural alteration of enzymes involved in RNA synthesis (DNA-dependent RNA polymerase) is the mechanism through which organisms become resistant to rifampin

Answer 537

common with TOF 5 Ts of cyanotic congenital heart disease: tetralogy of fallot, tricuspid atresia, transposition of the great vessels, truncus arteriosus, and total anomalous pulmonary venous return ASD, VSD, PDA and aortic coarctation are generally considered noncyanotic congenital heart diseases

Answer 538

aortic stenosis most common cause is degenerative (senile) calcinosis of the aortic leaflets

Answer 539

The interstitial and alveolar edema and exudate in ARDS result in large part from an increased pulmonary capillary permeability. The result is a decrease in lung compliance, an increase in the work of breathing, and worsened V/Q mismatching. The pulmonary capillary wedge pressure (PCWP) is typically normal. An elevated PCWP would be more suggestive of a cardiogenic cause in a pt with pulmonary edema

Answer 540

hyperventilation and decreased pCO2 hypocapnia causes cerebral vasoconstriction and decreased cerebral blood flow

Answer 541

common in the first several years after menarche and the last few years before menopause manifests with marked menstrual cycle variability

Answer 542

Vernet syndrome dysfunction of CN IX, X, XI loss of taste from posterior 1/3 of tongue (IX), loss of gag reflex and dysphagia (IX, X), hoarseness (X)

Answer 543

Intrinsic factor (IF) is a glycoprotein that is normally secreted by parietal cells in the stomach and is necessary for the absorption of vitamin B12 in the ileum. Pts who have undergone a total gastrectomy require lifelong parenteral vit B12 administration due to inability to produce IF

Answer 544

depolarizing neuromuscular-blocking agent, attaches to nAChR can cause significant potassium release and life threatening arrythmias in pts at high risk for hyperkalemia (burns, myopathies, crush injuries, denervating injuries)

Answer 545

can be challenged in cases in which a child is at significant risk for harm physicians are justified in obtaining a court injunction to proceed with life-saving medical treatment of the child

Answer 546

increases vagal tone and can be used to abolish paroxysmal supraventricular tachycardia the rectus abdominis is the most important muscle in achieving the increased intraabdominal and intrathoracic pressure of the Valsalva maneuver

Answer 547

Babinski sign (dorsiflexion of the toes), hyperreflexia, muscle weakness and spasticity indicate an upper motor neuron lesion LMN: atrophy, fasciculations, loss of tendon reflexes

Answer 548

On abdominal CT scans, the pancreas can be identified by its head in close association with the second part of the duodenum; by its body overlying the left kidney, aorta, IVC and superior mesenteric vessels; and also by the tail lying in the splenorenal ligament (exocrine pancreatic insufficiency: inability to normally metabolize fat)

Answer 549

Normal tracheal pO2 is 150 mm Hg and normal alveolar pO2 is 104 mm Hg. The equilibration of O2 in a normal individual at rest is perfusion-limited. Situations where O2 equilibration can become diffusion limited include disease states such as emphysema and pulmonary fibrosis, and physiologically in states of very high pulmonary blood flow, such as during exercise

Answer 550

WBC casts are formed in tubules, and are pathognomonic for acute pyelonephritis when accompanied by systemic manifestations of febrile illness. WBC casts are also seen with acute interstitial nephritis, but clinical presentation is different in that pts only have a low-grade fever and do not experience painful urination. Pyuria and bacteriuria are non-specific and are found in both upper and lower UTIs

Answer 551

Branched chain a-ketoacid dehydrogenase, similar to pyruvate and a-ketoglutarate dehydrogenase, requires several coenzymes: Thyamine pyrophosphate, Lipoate, Coenzyme A, FAD, NAD ('Tender Loving Care For Nancy') Some pts with maple syrup urine disease improve with high-dose thiamine treatment (thiamine-responsive), but most still require lifelong dietary restrictions

Answer 552

autosomal dominant disease caused by abnormal nucleotide mismatch repair. The mismatch repair system involves several genes, including MSH2 and MLH1, which code for components of the human MutS and MutL homologs. Mutations in these 2 genes account for around 90% of cases of Lynch syndrome

Answer 553

Upper motor neuron damage leads to spastic paralysis, hyperreflexia and an upgoing plantar reflex (Babinski) LMN lesions are from damage to the motor neurons of the anterior horn. Cause flaccid paralysis, areflexia, atrophy and fasciculation

Answer 554

Glycine is the most abundant amino acid in the collagen molecule It occurs AT LEAST every 3rd amino acid position. The amino acid formula of collagen is (-Gly-X-Y)333

Answer 555

'forty, fat, female, fertile' Estrogen-induced hypersecretion and progesterone-induced gallbladder hypomotility are responsible for the increased incidence of cholelithiasis in women who are pregnant or using oral contraceptives

Answer 556

Both ventricular hypertrophy and volume overload cause release of both ANP and BNP from the ventricular myocytes to facilitate natriuresis and diuresis

Answer 557

Pts with post-streptococcal glomerulonephritis present with edema, hematuria, and an antecedent history of streptococcal infection (impetigo, cellulitis, pharyngitis). Infection must be caused by a nephritogenic strain of group A B-hemolytic Streptococcus. The glomerulonephritis is mediated by a type III (immune complex) hypersensitivity reaction

Answer 558

Insulin opposes glucagon action Glucagon stimulates glycogenolysis, gluconeogenesis, lipolysis and ketone body production insulin increases glucose, amino acid and potassium uptake by cells, inhibits ketoacid formation and inhibits lipolysis

Answer 559

small, noncoding form of RNA that contains unusual nucleosides such as pseudouridine and thymidine. tRNA has a CCA sequence at its 3' end that is used as a recognition sequence by proteins, and that the 3' terminal hydroxyl group of the CCA tail is used as the binding site for the amino acid

Answer 560

oxidase-positive, non-lactose fermenting, gram negative organism common cause of UTIs in pts with indwelling catheters

Answer 561

associated with DiGeorge syndrome (congenital thymic and parathyroid aplasia, congenital cardiovascular anomalies)

Answer 562

anti-HIV medications that inhibit cleavage of the polypeptide precursor into mature viral proteins side effects: hyperglycemia, lipodystrophy, drug-drug interactions due to inhibition of cytochrome p-450

Answer 563

treated by sulfhydryl group supplementation N-acetyl cysteine provides the sulfhydryl groups NAC also acts as a glutathione substitute and binds to the toxic metabolite

Answer 564

causes steatorrhea and failure to thrive due to malabsorption secondary to pancreatic insufficiency, which can be corrected by pancreatic enzyme supplementation

Answer 565

virulent mycobacteria will grow as 'serpentine' cords on enriched media secondary to the presence of cord factor, a mycoside. Cord factor establishes virulence through neutrophil inhibition, mitochondrial destruction, and the induced release of tumor necrosis factor

Answer 566

Used in tx of prostate cancer GnRH agonist that causes first a transient increase, then a decrease in both testosterone and DHT levels Finasteride causes a discordant decrease in DHT level

Answer 567

most common cause is cytomegalovirus infection CMV retinitis most frequently affects AIDS pts with a CD4+ lymphocyte cound

Answer 568

combination of extended-spectrum penicillin with B-lactamase inhibitor effective against most Gram (-) enteric rods, including Pseudomonas aeruginosa and Bacteroides fragilis

Answer 569

noted for causing optic neuritis that results in color blindness, central scotoma, and decreased visual acuity may be reversible with discontinuation of the drug

Answer 570

Niacin is believed to inhibit hepatic VLDL production, mainly used to increase HDL levels (side effect: cutaneous flushing and pruritis, pre-treat with aspirin) Statins inhibit cholesterol synthesis and thereby up-regulate the LDL receptors Bile acid binding resins can cause constipation and abdominal bloating (potentially worsening diverticulosis), hypertriglyceridemia, cholesterol gallstones and vit K malabsorption

Answer 571

advanced wilson disease is often characterized by neuropsychiatric symptoms, including Parkinsonian-like tremor, rigidity, ataxia, slurred speech, drooling, personality changes, depression, paranoia and catatonia almost all pts with neuropsychiatric involvement will also have Kayser-Fleischer rings, which can be identified on slit lamp examination

Answer 572

can cause severe pseumembranous pharyngitis after acquiring the Tox gene via lysogenization by a temperate bacteriophage

Answer 573

Cases of typhoid fever in developed countries usually occur after a pt has traveled to an endemic region. Typhoid fever is caused by Salmonella Typhi or Paratyphi and presents with: escalating fever (with initial diarrhea or constipation), followed by abdominal pain, formation of rose spots on the chest/abdomen, and hepatosplemomegaly and hemorrhagic enteritis with possible bowel perforation

Answer 574

Intracranial berry aneurysms of the circle of Willis are often seen in pts with ADPKD when ruptured, they cause subarachnoid hemorrhage that presents with sudden onset of 'thunderclap headache' (+ nuchal rigidity)

Answer 575

The finding of multiple ring-enhancing lesions in an HIV pt is most likely due to toxoplasmosis

Answer 576

occurs due to rupture of cortical bridging veins. In young pts, it results from a fall or motor vehicle accident, and manifests with gradual onset of headache and confusion In elderly pts it may occur after a minor trauma and presents with a variety of neurologic symptoms (also gradual onset). Crescent shape on CT

Answer 577

mean corpuscular hemoglobin concentration (MCHC) is increased due to mild dehydration of the red blood cell. Markers of hemolysis are often evident and include elevated lactate dehydrogenase, reticulocytosis, increased indirect bilirubin and decreased haptoglobin

Answer 578

rare, but associated with 25% fatality rate 2/3 of lightening-related deaths occur within the first hour after injury, with fatal arrhythmias and respiratory failure as the most common causes. Pts with minor cutaneous involvement may still have major internal injury after lightening strikes and high-voltage electrical contact

Answer 579

most common benign lung tumor present as asymptomatic peripherally located 'coin lesions' in pts 50-60 years old composed of disorganized cartilage, fibrous and adipose tissue

Answer 580

IgA anti-tissue transglutaminase and IgA endomysial antibody are very sensitive and specific for the diagnosis of celiac disease small intestinal biopsy is confirmatory; severe atrophy and blunting of the villi along with a chronic inflammatory infiltrate of the lamina propria is seen symptoms (diarrhea, steatorrhea, nutritional deficiencies) subside with exclusion of gluten-containing products from the diet

Answer 581

A retained dead fetus in the uterus is associated with disseminated intravascular coagulation (DIC) and progressive hypofribrinogenemia monitoring of fibrinogen and platelet count is helpful in early identification of the onset of DIC in high risk pts Findings of DIC: prolonged PTT and PT, thrombocytopenia and microangiopathic hemolytic anemia, low fibrinogen, elevated fibrin split products (D-dimer), low factor V and VIII levels

Answer 582

autoimmune demyelinating disease within the plaques, loss of myelin sheaths and depletion of oligodendrocytes is seen oligoclonal bands of IgG may be detected in cerebrospinal fluid oligodendrocyte depletion is also seen in progressive multifocal leukoencephalopathy

Answer 583

Insidious-onset progressive exertional dyspnea, pulmonary function tests showing a restrictive profile, and surgical biopsy showing extensive interstitial fibrosis together with paraseptal and subpleural cystic airspace enlargement (honeycomb lung) are characteristic of idiopathic pulmonary fibrosis

Answer 584

used to correct single-base DNA defects induced spontaneously or by exogenous chemicals Glycosylases remove the defective base, and the corresponding empty sugar-phosphate site is cleaved and removed by the action of endonuclease and lyase. DNA polymerase then replaces the missing nucleotide, and ligase seals the final remaining nick

Answer 585

Hemoglobin concentration Oxygen saturation of hemoglobin (SaO2) Partial pressure of oxygen dissolved in blood (PaO2)

Answer 586

involves a neutral stimulus being repeatedly paired with a non-neutral stimulus that elicits a reflexive, unconditioned response. Over time, the formerly neutral stimulus is able to evoke a conditioned response by itself in the absence of the non-neutral stimulus

Answer 587

lamotrigine, levetiracetam, topiramate, valproic acid successfully treat most seizure types (focal or generalized at onset) [generalized: tonic-clonic, myoclonic] [for absence use ethosuximide]

Answer 588

carbamazepine, gabapentin, phenobarbital, phenytoin favored for focal onset seizures (involves 1 cerebral hemisphere at onset) and should usually be avoided in generalized epilepsy syndromes as they may aggravate seizure

Answer 589

Heart failure due to left ventricular (LV) diastolic dysfunction is the result of a decrease in diastolic LV compliance. Restrictive cardiomyopathy, as can be caused by amyloidosis, may cause diastolic dysfunction Infectious myocarditis and cardiotoxic agents including alcohol and doxorubicin tend to produce a dilated cardiomyopathy with predominantly systolic dysfunction

Answer 590

should be performed above the 7th rib in midclavicular line, the 9th rib along midaxillary line and the 11th rib along posterior scapular line Insertion of a needle lower than these points increases the risk of penetrating abdominal structures, and insertion of the needle on the inferior margin of the rib risks striking the subcostal neurovascular bundle

Answer 591

component of the renin-angiotensin-aldosterone system that acts on the principal and intercalated cells of the renal collecting tubules to cause resorption of sodium and water and loss of potassium and hydrogen ions

Answer 592

contralateral superior quadrantanopia [the lower fibers of the optic radiation carry information from the lower retina (upper contralateral visual field) and take a circuitous route anteriorly into the temporal lobe (Meyer's loop) before reaching the lingual gyrus of the striate cortex]

Answer 593

The carotid sinus is a dilatation of the internal carotid artery that lies at the bifurcation of the carotid artery. Blood pressure increases or external pressure on the carotid sinus walls, leading to vasodilatation, a decrease in heart rate and contractility, and a decrease in blood pressure Afferent fibers from the carotid sinus stretch receptors form a small carotid sinus nerve, Hering's nerve, which is a branch of the glossopharyngeal nerve (CN IX)

Answer 594

specific for SLE only present in 60% of cases, so absence does not rule out diagnosis Anti-Smith antibodies (anti-snRNPs) are also specific for SLE

Answer 595

found in the 30S ribosomal subunit contains a sequence complementary to the Shine-Dalgarno sequence on mRNA binding of these 2 complementary sequences is necessary for initiation of protein translation

Answer 596

Ether and other organic solvents dissolve the lipid bilayer that makes up the outer viral envelope loss of infectivity after ether exposure is a characteristic feature of enveloped viruses

Answer 597

occurs in pts with septic shock because of tissue hypoxia, which results in impaired oxidative phosphorylation and the shunting of pyruvate to lactate following glycolysis. Hepatic hypoperfusion also contributes to the buildup of lactic acid, as the liver is the primary site of lactate clearance

Answer 598

Elderly patients with dementia or hemiparesis may also have dysphagia, which is a risk factor for aspiration pneumonia. Dependent lung consolidation (superior region or lower lobes, posterior regions of upper lobes) is commonly seen in aspiration pneumonia

Answer 599

elevated in beta-thalassemia as beta-globin chain underproduction leads to decreased hemoglobin A synthesis glycemic control in diabetes mellitus is assessed by measuring glycated hemoglobin (HbA1c) levels, which correspond most closely with the average blood glucose levels over the previous 10-12 weeks HbA1c levels can be affected by alterations in red blood cell survival

Answer 600

can be caused by: NSAID use, head trauma, severe burns, acute stress, alcohol or tobacco use Erosions are mucosal defects that do not fully extend through the MUSCULARIS MUCOSA Acute erosive gastropathy can cause upper GI hemorrhage that leads to melena [vs an ulcer - penetrated through the mucosal layer and extends into the submucosal layers]

Answer 601

``` 3 Ps: Parathyroid tumor (hypercalcemia), pancreatic tumor (gastrin), pituitary adenoma (prolactin, ACTH) ``` Check family history in anyone with Zollinger-Ellison syndrome Genetic defect involves the MENIN gene on chromosome 11

Answer 602

MEN2a: Medullary carcinoma of thyroid (calcitonin), pheochromocytoma, parathyroid tumor MEN2b: medullary carcinoma of thyroid, pheochromocytoma, marfanoid habitus/mucosal neuromas

Answer 603

a-ketoglutarate dehydrogenase requires thiamine as a cofactor administration of glucose to thiamine-deficient pts (alcoholics) will result in Wernicke encephalopathy due to increased thiamine demand Wenicke encephalopathy presents with acute confusion, ophthalmoplegia and ataxia

Answer 604

located adjacent to the cerebral surface parasagittal meningiomas cause contralateral spastic paresis of the leg due to compression of the leg-foot motor area Benign and slow growing tumors (2nd most common in adults), psammoma bodies

Answer 605

A yellowish eyelid papule or plaque containing lipid-laden macrophages is most likely xanthelasma. Xanthelasma may occur in association with primary or secondary hyperlipidemia Cholestatic conditions such as primary biliary cirrhosis are a potential cause of hypercholesterolemia leading to xanthelasma

Answer 606

can survive intracellularly within macrophages can cause disseminated mycosis in immunocompromised pts clinical features: systemic symptoms (fever, weight loss), painful oral ulcers, lymphadenopathy, hepatosplenomegaly

Answer 607

Enthesopathies (inflammation at sites of tendon insertion) are common in ankylosing spondylitis involvement of the costovertebral and costosternal junctions may cause limitation of chest movements, resulting in hypoventilation [monitor chest expansion]

Answer 608

TZDs decrease insulin resistance by binding to peroxisome proliferator activated receptor gamma (PPAR-gamma), which is a transcriptional regulator of genes involved in glucose and lipid metabolism Adiponectin levels are low in type 2 diabetes, and treatment with TZDs increases th levels of adiponectin

Answer 609

body temperature greater than 40C is called hyperpyrexia may lead to permanent brain damage if left untreated emergent treatment should consist of increasing body heat loss (cooling) and is effective immediately as opposed to antipyretics (NSAIDs, acetaminophen)which take time to act

Answer 610

structural analogues of pyrophosphate, an important component of hydroxyapatite used in the treatment of osteoporosis, Paget's disease of the bone, and malignancy-induced hypercalcemia administered in the fasting state with plenty of water. The pt must stay upright for at least 30 mins to prevent reflux esophagitis

Answer 611

result of lithium's antagonizing effect on the action of vasopressin on principal cells within the collecting duct system

Answer 612

The mechanism of vanco resistance in organisms such as VRE is a substitution of D-lactate in the place of D-alanine during the process of peptidoglycan cell wall synthesis. This prevents the binding of vanco to its usual D-ala-D-ala binding site on the cell wall

Answer 613

Heavy chain and B2-microglobulin on all nucleated cells presents antigens to CD8+ cytotoxic T-cells type of antigen includes viruses, tumor proteins lears to apoptosis of the presenting cell

Answer 614

alpha and beta polypeptide chains APCs (Langerhans, macrophages, dendritic, B cells) present antigen to CD4+ T helper lymphocytes antigens are bacterial leads to activation of TH cells, stimulates immune response

Answer 615

used to compare the exposure of people with the disease (cases) to the exposure of people without the disease (controls) main measure of association is the exposure odds ratio

Answer 616

may cause exertional syncope AS murmur is a systolic ejection-type, crescendo-decrescendo murmur that starts after the first heart sound and typically ends before the A2 component of the second heart sound. The intensity of the AS murmur is proportional to the magnitude of the left ventricle-to-aorta pressure gradient during systole

Answer 617

occurs predominantly in the duodenum and proximal jejunum bypass of this segment of small bowel by gastrojejunostomy results in iron deficiency anemia malabsorption of Vit B12, folate, fat-soluble vitamins (especially D) and calcium may also be observed following gastric bypass procedures

Answer 618

direct indicator of alveolar ventilation status hypocapnia implies ongoing alveolar hyperventilation upper airway obstruction, reduced ventilatory drive, respiratory muscle fatigue, and decreased chest wall compliance are possible causes of alveolar hypoventilation and hypercapnia

Answer 619

Squamous --> columnar complication of long standing GERD and is called Barrett esophagus originally a protective response to injury by acidic stomach contents, Barrett esophagus significantly increases the risk of esophageal adenocarcinoma

Answer 620

Lethal tissue ischemia causes coagulative necrosis in most tissues, including the myocardium tissue architecture is preserved, anucleated cells the exception is ischemic cell death in the central nervous system, which causes liquifactive necrosis

Answer 621

abdominal pain, nausea, vomiting, diarrhea, piloerection, lacrimation and diaphoresis, yawning can occur following cessation or reduction in use of narcotics (like heroine) Non-life threatening, no seizures (as in alcohol and benzodiazepine withdrawal)

Answer 622

Pts with HIV often experience reactivation of latent EBV infections, with a resulting increased incidence of EBV-induced lymphoproliferative disorders

Answer 623

Vit B12 and folic acid deficiencies cause similar hematological pictures howerver, neurological dysfunction is only seen in pts with vit B12 deficiency If megaloblastic anemia due to vit B12 deficiency is mistakenly treated with folate alone, the neurologic dysfunction can worsen

Answer 624

occurs in children with febrile illness treated with salicylates (aspirin) consists of hepatic failure and encephalopathy histology: microvesicular steatosis of hepatocytes without inflammation and cerebral edema

Answer 625

Antiretroviral agents that selectively bind to the HIV envelope transmembrane glycoprotein gp41 prevent the conformational changes necessary for the viral membrane to fuse with the target cellular membrane these agents are therefore known as 'fusion inhibitors'

Answer 626

A cystic tumor in the cerebellum of a child is most likely a pilocytic astrocytoma biopsy will show a well-differentiated neoplasm comprised of spindle cells with hair-like glial processes that are associated with microcysts these cells are mixed with rosenthal fibers and granular eosinophilic bodies

Answer 627

can cause duodenal ulcers and is typically found in greatest concentration in the prepyloric area of the gastric antrum (site to biopsy)

Answer 628

primary virulence factor (without which it cannot cause disease) is a polysaccharide capsule that inhibits phagocytosis

Answer 629

second line tx for atrial fibrillation with rapid ventricular response increases cardiac contractility by blocking the Na-K-ATPase in cardiac myocytes leading to an increased intracellular calcium concentration, and it will decrease AV nodal conduction by a mechanism of increased parasympathetic tone

Answer 630

nonselective, irreversible a-1 and a-2 adrenergic antagonist that effectively reduces the number of receptors available for NE binding Because phenoxybenzamine is an irreversible antagonist, even high concentrations of NE cannot overcome its inhibitory effects

Answer 631

agonist at a-1 (vasoconstriction) and B1 receptors, less action at B2 (vasodilation)

Answer 632

causes impairments of platelet function and coagulation pathway abnormalities associated with prolonged bleeding time, prolonged PTT and decreased platelet aggregation in response to ristocetin

Answer 633

Local defense against Candida is performed by T-cells, wheras systemic infection is prevented by neutrophils For this reason, localized candidiasis is common in HIV-positive pts while neutropenic individuals are more likely to have systemic disease

Answer 634

unconscious shifting of emotions or desires associated with one person (ex. parent) to another (ex. therapist) can be positive or negative

Answer 635

detectable by cytogenetic karyotype analysis and is the most common genetic cause of congenital mental retardation Pts with Down syndrome are at increased risk of developing acute lymphoblastic leukemia and acute myelogenous leukemia

Answer 636

The combination of fixed segmental loss of upper extremity pain and temperature sensation, upper extremity lower motor neuron signs, and/or lower extremity upper motor neuron signs in the setting of scoliosis suggests a diagnosis of syringomyelia

Answer 637

At risk of injury during thyroidectomy due to its proximity to the superior thyroid artery and vein This nerve innervates the cricothyroid muscle

Answer 638

submucosal (Meissner) and myenteric (Auerbach) autonomic plexi are absent in the affected segment of the bowel in Hirschsprung disease. The submucosa of the narrowed area is the most superficial layer where the absence of ganglion cells can be seen (biopsy there)

Answer 639

carrier proteins for oxytocin and vasopressin (ADH) carried by unique neurophysins from their site of production in the cell bodies of the paraventricular and supraoptic nuclei to their site of release in the axon terminals of the posterior pituitary point mutations in neurophysin II underlie most cases of hereditary hypothalamic diabetes insipidus, a disorder resulting from insufficient ADH release into the systemic circulation

Answer 640

presents with onspecific gastrointestinal (anorexia, nausea, vomiting) and neurologic (fatigue, confusion, weakness) symptoms changes in color vision are a more specific, but rarer, finding life-threatening ventricular arrhythmias are the most serious complication

Answer 641

found in cardiac tissue and on renal juxtaglomerular cells, but not on vascular smooth muscle blockade of the B1 receptor leads to decreasing cAMP levels in cardiac and renal tissue without affecting cAMP levels in vascular smooth muscle Atenolol is a selective B1 adrenergic antagonist at low doses

Answer 642

Gs --> adenylyl cyclase --> ATP to cAMP --> protein kinase A activation

Answer 643

Gq --> phospholipase C --> DAG + IP3 --> protein kinase C activation and calcium release from sarcoplasmic reticulum

Answer 644

stimulates FSH and LH release and is useful for the treatment of infertility Nonpulsatile (constant) infusion of GnRH, or a longer-lasting analogue, suppresses FSH and LH release and is useful for the treatment of prostate cancer, endometriosis etc

Answer 645

phosphorylated in the liver to F1P and rapidly metabolized because it bypsses PFK-1, the major rate limiting enzyme of glycoysis other sugars (glucose, galactose, mannose) enter glycolysis prior to PFK-1 and as a result are metabolized more slowly

Answer 646

Exertional dyspnea, pneumonia resulting in life-threatening acute chest syndrome, and recurrent abdominal and bone pain are clinical features of sickle cell anemia sickle cell anemia results from a point mutation that causes valine to substitute for glutamic acid in the 6th position of the b-globin chain of hemoglobin

Answer 647

Aldose reductase converts glucose into sorbitol, which is further matabolized into fructose by sorbitol dehydrogenase this pathway is most active in the seminal vesicles the lens also contains significant levels of sorbitol dehydrogenase, which become overwhelmed in the setting of hyperglycemia other tissues, such as the retina, renal papilla, and schwann cells, have much less sorbitol dehydrogenase activity

Answer 648

Decreased cardiac output triggers a number of compensatory mechanisms Renin-angiotensin-aldosterone activation and increased sympathetic output raise arterial resistance (afterload) and exacerbate heart failure by making it more difficult for the failing heart to pump blood to the tissues

Answer 649

increase cholesterol excretion by the liver (increase cholesterol content of bile). Along with the reduction in serum LDL, there is an increased risk for gallstone formation

Answer 650

most common type of thyroid cancer diagnosis can be made on FNA by characteristic cell morphology showing large cells with nuclei containing finely dispersed chromatin with a ground-glass appearance (orphan annie eyes)

Answer 651

decreased levels of acetylcholine in the nucleus basalis of Meynert (memory and cognition) and hippocampus (new memory formation) caused by diminished activity of choline acetyltransferase in these cerebral structures

Answer 652

huntington disease | NMDA receptors are depleted in the striatum

Answer 653

parkinson disease

Answer 654

can be performed by injecting anesthetic intravaginally in the region of the ischial spine blocking the pudendal nerve provides anesthesia to the majority of the perineum; additional blockade of the genitofemoral and ilioinguinal nerves would provide complete perineal and genital anesthesia

Answer 655

infection can lead to Guillan-Barre syndrome (GBS) in rare instances GBS is a demyelinating syndrome of the peripheral nerves characterized by ascending muscle weakness and paralysis

Answer 656

Rheumatic fever and acute post-streptococcal glomerulonephritis are the late sequelae of Group A Strep infections PSGN can follow either a skin infection (impetigo) or an episode of streptococcal pharyngitis, whereas rheumatic fever is associated only with streptococcal throat infection

Answer 657

product of lipid peroxidation and free radical injury, accumulating in aging cells (especially in pts with malnutrition and cachexia) sign of 'wear and tear' or aging, yellow-brown and finely granular

Answer 658

Exacerbation of myasthenia gravis in a pt treated with cholinesterase inhibitors occurs due to myasthenic or cholinergic crisis The endrophonium (Tensilon) test helps to differentiate these 2 conditions clinical improvement after edrophonium administration indicates that the pt is undertreated (myasthenic crisis)

Answer 659

Osteoporosis is a common cause of pathological vertebral fractures chronic systemic use of corticosteroids such as prednisone promotes osteoporosis, and therefore may cause such fractures

Answer 660

(and other B-blockers) decrease aqueous humor production by the ciliary epithelium Glaucoma is due to increased intraocular pressure, develops due to decreased outflow or increased production of aqueous humor

Answer 661

use darkfield microscopy, reveals helical motile organisms

Answer 662

can be antibody- or cell-mediated acute cellular rejection is associated with diffuse lymphocytic infiltration of the renal vasculature (endothelitis), tubules, and interstitium

Answer 663

causes at least 80% of cases of hemolytic-uremic syndrome (HUS) in north america recognized as a common cause of bloody diarrhea in developed countries associated with consumption of undercooked ground beef and elaborates a Shiga-like toxin capable of inhibiting protein synthesis in colonic mucosal cells and renal endothelial cells this strain of E. coli is unable to ferment sorbitol and does not produce a glucuronidase

Answer 664

widely used UVB radiation absorbers (UVB is the major cause of sunburns etc) do not significantly absorb or block radiation in the UVA wavelength range (zinc-oxide containing sunscreens do)

Answer 665

bilobed nuclei packed with large eosinophilic granules major basic protein released by eosinophils normally functions to kill helminths it is also thought to contribute to the bronchial epithelial damage sustained by pts with atopic (extrinsic allergic) asthma

Answer 666

leads to acute renal failure due to the precipitation of calcium oxalate crystals in renal tubules and subsequent damage to tubular epithelium typical clinical findings include anion gap metabolic acidosis, increased osmolar gap, and presence of calcium oxalate crystals in urine

Answer 667

can reverse the toxicity of methotrexate in non-cancerous cells in the GI mucose and bone marrow if administered at the appropriate time leucovirin, a 5-formyl-derivative of tetrahydrofolic acid, does not require the action of dihydrofolate reductase for its conversion to tetrahydrofolate

Answer 668

Osteoporosis (porous bone) represents loss of 'total bone mass' that results in trabecular thinning subperiostial resorption with cystic degeneration is characteristic of hyperparathyroidism Vit D results in 'excessive unmineralized osteoid' resulting in low mineral density Osteopetrosis is characterized by the 'persistence of primary unmineralized spongiosa in the medullary canals'

Answer 669

Low bone density is a well-known complication of hyperprolactinemia that is associated with prolactin-induced hypogonadism (low estrogen). Vaginal dryness is another very common manifestation of estrogen deficiency

Answer 670

caused by cystathionine synthetase deficiency affected individuals manifest with symptoms resembling those of Marfan syndrome, particularly ectopia lentis, and many experience some form of developmental delay They are also at risk of developing thromboembolism. About 50% of affected pts respond to high doses of vitamin B6 (pyridoxine)

Answer 671

most common cause is rupture of apical subpleural blebs these blebs may arise due to distal acinar (paraseptal) emphysema tall, thin, young men are most commonly affected other types of emphysema may predispose to a secondary spontaneous pneumothorax compensatory and obstructive hyperinflation cause distention of normal lung parenchyma and would be unlikely to cause pneumothorax

Answer 672

Non-neoplastic polyps (hyperplastic, hamartomatous, inflammatory) usually do not progress into adenocarcinoma of the colon Adenomatous polyps can undergo malignant transformation Villous adenomas are more likely than tubular adenomas to progress to adenocarcinoma

Answer 673

congenital abnormalities caused by impaired development of the posterior fossa Arnold-Chiari type I is relatively benign and may manifest in adulthood (headaches, ataxia) Arnold-Chiari type II is severe and evident in the newborn

Answer 674

marker of epithelial cell origin

Answer 675

presence of rhomboid-shaped calcium pyrophosphate crystals is diagnostic positively birefringent under polarized light (opposite of gout) Knee joint is involved in more than 50% of cases

Answer 676

results from changes in the membrane permeability to K+ and Na+ ions Depolarization results from massive influx of Na+ through voltage-gated Na+ channels Repolarization occurs due to closure of voltage-gated Na+ channels and opening of voltage-gated K+ channels K+ ion permeance is highest during the repolarization phase of the action potential

Answer 677

low levels of maternal serum a-fetoprotein and estriol and increased levels of B-hCG and inhibin A elevated a-fetoprotein levels are seen in multiple gestation, open neural tube defects and abdominal wall defects

Answer 678

autosomal recessive genetic absence of CD18 --> inability to synthesize integrins Integrins are necessary for leukocytes to exit the bloodstream, and sequelae of this illness include recurrent skin infections WITHOUT pus formation, delayed detachment of the umbilical cord and poor wound healing

Answer 679

The Hib vaccine consists of PRP capsular polysaccharide conjugated with either tetanus or diphtheria toxoid protein conjugation causes a T-cell mediated immune response leading to immunoglobulin class switching and generation of memory B-lymphocytes this response would not occur with pure polysaccharide immunization

Answer 680

Moderately increased albuminuria (urine albumin

Answer 681

most often caused by the rapid deceleration that occurs in motor vehicle collisions The most common site of injury is the aortic isthmus, which is tethered by the ligamentum arteriosum and is relatively fixed and immobile compared to the adjacent descending aorta

Answer 682

Benzodiazepines (lorazepam) are first-line agents in the management of status epilepticus Phenytoin (or fosphenytoin) is administered simultaneously to prevent the recurrence of seizures. Phenytoin inhibits neuronal high-frequency firing by reducing the ability of Na+ channels to recover from inactivation

Answer 683

occurs when a thrombus from the venous system crosses into the arterial circulation via an abnormal connection between the right and left cardiac chambers (patent foramen ovale, atrial septal defect, or ventricular septal defect). Atrial left-to-right shunts cause wide and fixed splitting of S2 and can facilitate paradoxical embolism due to periods of transient shunt reversal

Answer 684

Many drugs can accelerate (induce) the hepatic metabolism of warfarin leading to reduced anticoagulation and enhanced thrombotic risk. These include antibiotics such as rifampin and griseofulvin as well as antiepileptic drugs such as barbituates, carbamazepine, and phenytoin Warfarin metabolism may be inhibited by antibiotics such as trimethoprim, isoniazid and fluconazole, as well as other drugs such as cimetidine. Inhibition of warfarin metabolism can increase the risk of bleeding

Answer 685

An S3 is a low frequency heart sound that can be physiologic in younger individuals. It is typically pathologic in older adults, and in these pts, it generally results from left ventricular systolic failure or restrictive cardiomyopathy The S3 sound can be accentuated by having the pt lie in the left lateral decubitus position and fully exhale (decreases volume in lungs to move heart closer to chest wall)

Answer 686

are absorbed into the thyroid gland via the sodium-iodide symporter. High levels of any one substance will significantly reduce the uptake of the others due to competitive inhibition

Answer 687

Hypertension! Hypertension, smoking, diabetes mellitus, and hypercholesterolemia are all major risk factors for atherosclerosis, which predisposes more to aortic aneurysm formation than aortic dissection

Answer 688

as the radius of a sphere with constant surface tension decreases, the distending pressure increases; thus, smaller spheres collapse before larger ones. Surfactant counteracts alveolar collapse by decreasing surface tension as the alveolar radius decreases

Answer 689

Coarse erythrocyte basophilic stippling and microcytic hypochromic anemia are common peripheral blood smear findings in lead poisoning. High-risk groups include young children ingesting paint chips and industrial workers inhaling particulate lead

Answer 690

inhibit ovulation by decreasing synthesis of FSH and LH in the anterior pituitary. Their effects on cervical mucus and endometrium play a minor role

Answer 691

usually occurs in the fragile germinal matrix and increases in frequency with decreasing age and birth weight. Common complication of prematurity that can lead to long-term neurodevelopmental impairment

Answer 692

months - years following transplant In lung transplant, the immune reaction affects the small airways, causing bronchiolitis obliterans syndrome. Symptoms include dyspnea and wheezing

Answer 693

Normally, metabolic acidosis is partially compensated for by respiratory alkalosis when the steady-state PaCO2 persists above the range given by Winter's formula PaCO2 =1.5*HCO3- +8+/-2 the patient has a superimposed respiratory acidosis (respiratory failure)

Answer 694

best long-term treatment choice for chronic tophaceous gout regardless of the urinary excretion of uric acid In pts who excrete large amounts of uric acid, uricosuric drugs (probenecid, sulfinpyrazone) should be avoided to prevent uric acid nephrolithiasis

Answer 695

--> High output congestive heart failure and neurological symptoms are strongly suggestive of wet beriberi (thiamine deficiency)

Answer 696

Most enveloped nucleocapsid viruses acquire their lipid bilayer envelope by budding through the plasma membrane of the host cell exceptions include the herpesviruses, which bud through and acquire their envelope from the host cell nuclear membrane

Answer 697

found in a variety of poisonous mushrooms (Amanita phalloides, known as death cap) and are potent inhibitors of RNA polymerase II (halting mRNA synthesis)

Answer 698

Protein M is the major virulence factor for Strep pyogenes. It inhibits phagocytosis and complement activation, mediates bacterial adherence, and is the target of type-specific humoral immunity to S. pyogenes

Answer 699

Reduction in the slope of the curve depicting lung volume versus distending pressure indicates decreased lung compliance (the hallmark of pulmonary fibrosis)

Answer 700

normal on histologic examination

Answer 701

most commno lung cancer in the general population also the most common subtype in women and nonsmokers located peripherally and consists of tumor cells that form glandular or papillary structures

Answer 702

the main modes of transmission of hep B virus include sexual and percutaneous the risk of sexual transmission of hep C is low

Answer 703

postpartum blues - benign, delf-limited change in affect that lasts up to 10 days postpartum. Treated with watchful waiting and the knowledge that up to 20% of these women will develop postpartum depression

Answer 704

typically noted by 2-4 weeks of age, after which the child prefers to hold the heard tilted to one side most commonly the result of malposition of the head in utero or birth trauma most cases resolve with conservative therapy and stretching exercises

Answer 705

X-linked recessive, mutations in gene coding for factor VIII Factor VIII is synthesized by the liver and stored in endothelial cells Desmopressin acetate (DDAVP) is a synthetic vasopressin analog that releases von Willebrand factor and factor VIII from the endothelium. It is used in the treatment of mild-moderate hemophilia A

Answer 706

(and other class III and class IA antiarrhythmic agents) cause lengthening of the cardiac action potential, which manifests as QT interval prolongation on ECG. In contrast to other drugs, QT prolongation caused by amiodarone is associated with very low risk of torsades de pointes and other proarrhythmias

Answer 707

rapidly acting antiarrhythmic used to quickly convert people out of PSVT (drug of choice) rapidly cleared and has a half-life of only less than 10 seconds commonly causes chest burning (bronchospasm), flushing and high grade block as adverse reactions (used for chemical stress tests)

Answer 708

The vagus nerve provides some cutaneous sensation to the posterior external auditory canal via its small auricular branch sensation to the rest of the canal is from CNV3 a vasovagal syncopal episode results from stimulation of the vagus nerve, leading to a decrease in blood pressure and heart rate

Answer 709

The zinc containing d-Aminolevulinate dehydratase and ferrochelatase are enzymes in the heme biosynthetic pathway that are inactivated by lead. Thus, in lead poisoning, d-ALA and protoporphyrin IX accumulate, and the production of heme is decreased, leading to microcytic anemia secondary to a lack of hemoglobin

Answer 710

can present with symptoms / signs of hypertension in the arterial tree proximal to the coarctation, and of hypofusion of the lower extremities, especially during ambulation. Collateral circulation to the distal aorta results in dilated intercostal arteries. The triad of upper body hypertension, diminished lower extremity pulses, and enlarged intercostal artery collaterals is typical of adult-type coarctation and is not seen in other congenital cardiovascular malformations

Answer 711

An abnormally prominent, upsloping left atrial 'v wave' during cardiac catheterization is a major hemodynamic finding of mitral regurgitation

Answer 712

most likely due to N. gonorrhoeae or C. trachomatis, both of which cause dysuria and mucopurulent urethral discharge. The standard of treatment for sexually transmitted urethritis presumes infection by both organisms: ceftriaxone is given for N. gonorrhea and doxycycline or azithromycin is given for C. trachomatis

Answer 713

major amino acid responsible for transferring nitrogen to the liver for disposal. During the catabolism of proteins, amino groups are transferred to a-ketoglutarate to form glutamate. Glutamate is then processed in the liver to form urea, the primary disposal form of nitrogen in humans. Free ammonia is also excreted into the urine by the kidney for regulation of acid-base status

Answer 714

all pts beginning treatment with TNF-a inhibitors should be evaluated for latent TB

Answer 715

protein kinase involved in activation of signaling pathways for melanocyte proliferation, and the BRAF V600E (glutamic acid for valine) mutation is seen in 40-60% of pts with melanoma

Answer 716

blocker of GP IIb/IIIa receptor GP IIb/IIIa is either deficient or defective in pts with Glanzmann thrombasthenia

Answer 717

A psoas abscess can occur as the result of hematogenous or lymphatic seeding from a distant site or by spread from an adjacent site. Pts can present with fever, back or flank pain, inguinal mass, and difficulty walking. Inflammation of the psoas muscle causes pain when the hip is extended (psoas sign)

Answer 718

Bleeding after a tooth extraction and a history of hemiarthrosis is suggestive of hemophilia. Decreased levels of factor VIII or IX lead to failure to convert prothrombin into thrombin and deficient thrombus formation Addition of thrombin to the blood of a pt with hemophilia results in clotting

Answer 719

autosomal recessive disorder caused by a deficiency in B-hexosaminidase A, which results in accumulation of GM2 ganglioside. It is characterized by progressive neurodegeneration (at 2-6 months - weakness, hypotonia, loss of motor skills, abnormal startle reflex) and a cherry-red macular spot. In contrast to Niemann-Pick disease, there is no hepatosplenomegaly

Answer 720

assists in abduction of the arm and stabilization of the glenohumeral joint. the most commonly injured structure in rotator cuff syndrome is the tendon of the supraspinatus muscle ('empty can supraspinatus test') this tendon is vulnerable to injury due to impingement between the acromion and the head of the humerus

Answer 721

characterized by aggressive, rapid growth and a 'starry sky' microscopic appearance. Translocation of the c-myc oncogene on the long arm of chromosome 8 with the Ig heavy chain region on chromosome 14 [t(8;14)] produces a nuclear phosphoprotein (c-myc) that functions as a transcription activator

Answer 722

[t(9,22)], Bcr-abl --> increased tyrosine kinase activity

Answer 723

5-a-reductase inhibitor, can treat male pattern baldness

Answer 724

intermittent respiratory symptoms in pts with a normal CXR, occasional sputum eosinophils and reduced FEV1 suggest a diagnosis of asthma. Extrinsic allergic asthma provoked by inhaled allergens such as animal dander is the most common type

Answer 725

Inherited defects involving the interferon-gamma signaling pathway result in disseminated myobacterial disease in infancy or early childhood. Pts require lifelong treatment with antimyobacterial agents

Answer 726

acts as a CO2 carrier on the surface of the carboxylase enzyme and is necessary for numerous conversions, including pyruvate to oxaloacetate. Excessive ingestion of avidin (which is found in egg whites) has been associated with biotin deficiency

Answer 727

The GABAa and GABAc receptors are ion channels (Cl- influx) while the GABAb receptor is linked to a G-protein (K+ efflux, decreased Ca++ influx, inhibition of adenylyl cyclase) benzodiazepines, barbituates and alcohol all bind to different components of the GABAa receptor and facilitate the inhibitory action of GABA in the central nervous system ex. lorazepam (a benzo) allosterically binds to the GABAa receptor

Answer 728

caused by increased levels of ammonia and other neurotoxins in the circulation that lead to increased inhibitory neurotransmission and impaired excitatory neurotransmitter release. Hepatic encephalopathy is frequently precipitated by a stressor that alters the ammonia balance (gastrointestinal bleeding, increased dietary protein). Asterixis (flapping tremor) is specific for metabolic encephalopathies

Answer 729

Only 10% of total perfusion through the myocardial capillaries of the LV occurs during systole, while the majority of left ventricular blood flow occurs during diastole The systolic reduction in coronary blood flow is greated in the subendocardium of the LV

Answer 730

Lipids (triglycerides, cholesterol and phospholipids) are digested in the duodenum and absorbed in the jejunum. Bile acids are necessary for lipid absorption. Cholecystectomy typically has little effect on lipid digestion and absorption though pts may find it difficult to eat a large fatty meal

Answer 731

earliest lesion of atherosclerosis and present in all ppl over 10. They are composed of intimal, lipid-filled foam cells, derived from macrophages and SMC that have engulfed lipoproteins. Although some fatty streaks may progress to full-fledged atherosclerotic plaques later in life, in general their occurance and location in a child do not predict the occurrence or location of atheromatous plaques later in life

Answer 732

Polymyalgia rheumatica occurs in more than half of pts with temporal arteritis. It is characterized by neck, torso, shoulder and pelvic girdle pain and morning stiffness. Fatigue, fever and weight loss may also occur monocular vision loss is a common complication of temporal arteritis

Answer 733

genetically unstable virus because it lacks proofreading 3' --> 5' exonuclease activity in its RNA polymerase and its enveloped glycoprotein contains a hypervariable region prone to frequent genetic mutation

Answer 734

visceral obesity as measured by waist-to-hip ratio

Answer 735

In pts with TOF, squatting increases SVR and decreases R to L shunting, thereby increasing pulmonary blood flow. Squatting thus counteracts arterial desaturation during hypoxemic spells

Answer 736

maladaptive pattern of behavior characterized by feelings of inadequacy, timidity and fear of rejection

Answer 737

Long-term acid suppression with proton pump inhibitors (ex. omeprazole) may be associated with an increased risk of osteoporotic hip fractures, possibly as a result of decreased calcium absorption Others = anticonvulsants that induce CYP450, aromatase inhibitors, GnRH agonists, glucocorticoids, unfractionated heparin

Answer 738

typically associated with subclinical infection in the immunocompetent, with the occasional individual developing a mononucleosis-like syndrome that is Monospot negative. In the immunocompromised, primary or reactivated CMV infection can result in severe retinitis, pneumonia, esophagitis, colitis and /or hepatitis

Answer 739

maintain spermatogenesis, release inhibin, and secrete Mullerian inhibiting factor during male embryogenesis. Inhibin provides negative feedback on FSH secretion by the anterior pituitary

Answer 740

UV-specific endonuclease deficiency is the most common cause of the autosomal recessive disorder xeroderma pigmentosum --> photosensitivity, poikiloderma, hyperpigmentation, skin cancers

Answer 741

Mycoplasma pneumonia is the causative agent in walking pneumonia and many cases of tracheobronchitis. It is an organism with no peptidoglycan cell wall; it only has a phospholipid bilayer cell membrane. It shares antigens with human erythrocytes, and when the body mounts a response against these antigens it also lyses RBCs leading to anemia. The antibodies causing this RBC destruction are referred to as cold agglutinins

Answer 742

vasculitis of medium-sized arteries that presents with persistent fever for >5 days, bilateral conjunctivitis, cervical lymphadenopathy, mucocutaneous involvement, and edema of hands/feet. Coronary artery aneurysms are a serious complication of Kawasaki disease

Answer 743

commonly used for the treatment of painful diapetic neuropathy have stronger anticholinergic properties than heterocyclics or SSRIs and should be used with caution in pts with BPH as they may cause urinary retention

Answer 744

The paralytic action of nondepolarizing neuromuscular junction (NMJ)-blocking drugs can be reversed by anticholinesterase agents such as neostigmine Siccinylcholine is a depolarizing NMJ blocker that is augmented by neostigmine during phase I block but reversed by neostigmine during phase II block. The duration of paralysis caused by succinylcholine depends largely on its catabolism by plasma cholinesterase

Answer 745

Nafcillin, methicillin and oxacillin active against isolates of S. aureus and S. epidermidis that are resistant to other penicillins not effective against MRSA

Answer 746

tear in the gastric mucosa near the gastroesophageal junction typically the result of repetitive, forceful vomiting, which can lead to metabolic alkalosis

Answer 747

common opportunistic pathogen that causes disseminated disease in HIV+ pts Pts with CD4+ counts

Answer 748

one of the most common autosomal dominant disorders result of heterozygous or homozygous LDL receptor gene mutations, which cause hepatocyte under-expression of functional LDL receptors can lead to accelerated atherosclerosis and early-onset coronary artery disease

Answer 749

drug of choice for prevention of venous thrombosis in non-ambulatory pts or pts undergoing elective surgery, especially hip and knee. Heparin increases the effect of the naturally occurring anticoagulant antithrombin-III (by binding and causing a conformational change)

Answer 750

M3 FAB variant of AML affects adult pts and may present with DIC cytogenetic abnormality t(15,17) leads to formation of fusion gene PML/RARa that is unable to signal for proper cellular differentiation as the normal retinoic acid receptor can tx with all-trans-retinoic acid (ATRA) stimulates differentiation and can induce remission

Answer 751

true hydrocephalus is an increase in CSF volume and pressure that occurs due to the abnormal production, flow, or absorption of CSF the pressure increase then causes ventricular enlargement In hydrocephalus ex vacuo, ventricular enlargement occurs due to brain atrophy (alzheimer, pick disease etc) and is not accompanied by increase in CSF pressure

Answer 752

can result from pressure on the esophagus by a dilated left atrium the left atrium is commonly enlarged in pts with mitral stenosis and left ventricular failure

Answer 753

tyrosine becomes essential in PKU pts because it can no longer be synthesized from phenylalanine PKU results from an inability to convert phenylalanine to tyrosine by the phenylalanine hydroxylase system usually due to an abnormality in the phenylalanine hydroxylase enzyme

Answer 754

causative agent of 'walking pneumonia', a condition characterized by a nagging nonproductive cough, low-grade fever and malaise often, the CXR suggests a severe pneumonia even though the pt appears relatively well mycoplasma species require cholesterol supplementation in order to grow on artificial media

Answer 755

most commonly affects young black women and presents with malaise, cough and varied cutaneous findings including erythema nodosum. CXR reveals bilateral hilar lymphadenopathy. Transbronchial biopsy showing non-caseating granulomas is necessary for diagnosis

Answer 756

aldosterone antagonist with mild diuretic effects based on the results from the RALES trial, addition of low dose spironolactone to standard therapy significantly reduced morbidity and mortality in class III and IV heart failure pts the benefits of spironolactone in HF pts are more than likely secondary to inhibition of the neurohormonal effects of aldosterone leading to decreased ventricular remodeling and cardiac fibrosis

Answer 757

The transient procoagulation/anticoagulant imbalance present at the start of warfarin therapy is further exaggerated by a protein C deficiency (or S), leading to a relative hypercoagulable state with thrombotic occlusion of the microvasculature and skin necrosis

Answer 758

C5-C7 ventral rami innervated the flexor muscles of the upper arm and provides sensory innervation to the lateral forearm the musculocutaneous nerve is derived from the upper trunk of the brachial plexus and can be injured by forceful injuries that cause separation of the neck and shoulder

Answer 759

NSAID-associated chronic renal injury is morphologically characterized by papillary necrosis and chronic interstitial nephritis glomerular and vascular abnormalities, if present, are usually mild or may be seen only in advanced stages. NSAIDs-associated nephropathy is common, especially in pts suffering from chronic pain

Answer 760

in lobar pneumonia, the inflammation involves an entire lobe of the lung the course of the disease includes: - congestion (red, heavy, boggy, bacteria exudate) - red hepatization (red, firm, airless) - gray hepatization (pale and firm) - resolution (normal)

Answer 761

related primarily to a decrease in free fatty acid oxidation secondary to excess NADH production by the 2 major alcohol metabolism enzymes, alcohol dehydrogenase and aldehyde dehydrogenase

Answer 762

autoantibodies to the hemidesmosomes along the basement membrane of the dermal-epidermal junction

Answer 763

The wheal observed after an insect sting results from an allergic, or Type I hypersensitivity reaction The allergens in the insect venom result in antibody class switching to IgE on initial exposure, and subsequent exposure results in degranulation of mast cells and basophils with release of histamine and heparin among other vasoactive mediators This degranulation can cause a response as mild as an urticarial wheal, or as severe as anaphylaxis

Answer 764

cell-cycle specific agents that prevent proper separation of chromosomes into daughter cells during the M-phase of the cell cycle the main dose limiting side effect of vincristine is neurotoxicity, which commonly manifests as peripheral neuropathy

Answer 765

blunt trauma to the globe can cause orbital blowout fractures. These fractures most commonly involve the medial or inferior orbital walls, because the bone bordering the ethmoid and maxillary sinuses is thin

Answer 766

The inferior vena cava courses through the abdomen and inferior thorax in a location anterior to the right half of the vertebral bodies the renal veins join the IVC at the level of L1/L2, and the common iliac veins merge to become the IVC at the level of L4

Answer 767

The pO2 in the left atrium and ventricle is lower than that in the pulmonary capillaries due to mixing of oxygenated blood from the pulmonary veins with deoxygenated blood arising from the bronchial arteries and thebesian veins

Answer 768

Prolonged burning substernal pain and ST segment elevation in leads I and V3-V6 is strongly suggestive of anterolateral left ventricle infarction common consequences of left ventricle infarction include left ventricular failure, cardiogenic acute pulmonary edema, pulmonary venous hypertension (congestion) and transudate of plasma into the lung interstitium and alveoli

Answer 769

Endometrial cells undergo apoptosis upon withdrawal of endocrine stimulation by progesterone

Answer 770

antidiuretic hormones act on the medullary segment of the collecting duct to increase urea and water reabsorption, allowing for the production of maximally concentrated urine

Answer 771

Colony-stimulating factors, prolactin, growth hormones and cytokines utilize tyrosine-associated receptors and the JAK/STAT signaling pathway

Answer 772

symptoms are caused by impaired collagen formation: hemorrhages, subperiosteal hematomas, bleeding into joint spaces, gingival swelling, secondary periodontal infection, anemia, hyperkeratotic papular rashes, impaired wound healing, and weakened immune response to local infections

Answer 773

The adrenal cortex consists of 3 distinct zones: the outer zona glomerulosa, the middle zona fasciculata, and the innter zona reticularis (GFR). The zona glomerulosa synthesizes mineralocorticoids (ex. aldosterone), the zona fasciculata predominantly produces cortisol, and the zona reticularis predominantly produces androgens

Answer 774

main effect is to stimulate sodium absorption and potassium and H+ ion excretion at the distal renal tubule. Hypokalemia of hyperaldosteronism can cause profound muscle weakness

Answer 775

Because viruses must use eukaryotic ribosomes for protein synthesis, they must convert their polycistronic genome into monocistronic mRNA some viruses accomplish this through the production of a polyprotein product from a single mRNA transcript this product is later cleaved by a viral protease to generate a complete set of functional, individual viral proteins ex. the picornaviridae family (echovirus)

Answer 776

GTP is synthesized by succinyl-CoA synthetase during the conversion of succinyl-CoA to succinate in the citric acid cycle during gluconeogenesis, phosphoenolpyruvate carboxykinase uses GTP to synthesize phosphoenolpyruvate from oxaloacetate

Answer 777

most common cause is Candida albicans can also be: CMV, HSV-1 diagnosis relies on endoscopic and microscopic findings

Answer 778

Potassium iodide competitively inhibits thyroid uptake of radioactive iodine isotopes and is often administered following nuclear accidents to protect the thyroid and prevent development of radiation-induced thyroid carcinoma

Answer 779

Presbyopia and skin wrinkles are age-related changes Presbyopia occurs due to denaturation of structural proteins within the lens, leading to loss of lens elasticity (can compansate for myopia by displacing the image backward, so that it focuses on the retina) decreased synthesis and increased breakdown of collagen and elastin contribute to the development of skin wrinkles

Answer 780

In the lungs, the binding of oxygen to hemoglobin drives the release of H+ and CO2 from hemoglobin (Haldane effect) In the peripheral tissues, high concentrations of CO2 and H+ facilitate oxygen unloading from hemoglobin (Bohr effect)

Answer 781

Almost all volatile anesthetics increase cerebral blood flow it is an undesirable effect as it results in increased ICP other important effects of inhaled anesthetics are myocardial depression, hypotension, respiratory depression and decreased renal function

Answer 782

characterized by atherosclerosis of the mesenteric arteries, resulting in diminished blood flow to the intestine after meals this causes postprandial epigastric pain ('intestinal angina') with associated food aversion / weight loss Its pathogenesis is similar to angina pectoris

Answer 783

IA: Disopyramide, Quinidine, Procainamide (Double Quarter Pounder) - intermediate inhibition of phase 0 depolarization - prolonged AP IB: Lidocaine, Tocainide, Mexiletine (Lettuce, Tomato, Mayo) - weak inhibition of phase 0 depolarization - shortened AP IC: Motricizine, Flecainide, Propafenone (More Fries Please) - strong inhibition of phase 0, no AP length change

Answer 784

Disopyramide, Quinidine, Procainamide sodium channel blocking agents that slow phase 0 of the ventricular myocyte action potential and prolong repolarization as well as the refractory period of these cells

Answer 785

delta agent, hep delta virus, hep D virus replication-defective RNA virus that is only capable of causing infection when encapsulated with HBsAg

Answer 786

carcinoid tumors confined to the intestine do not cause carcinoid syndrome as their secretory products are metabolized by the liver before entering the systemic circulation in contrast, intestinal carcinoids that metastasize to the liver and extraintestinal (bronchial) carcinoids release vasoactive substances that avoid first-pass metabolism, resulting in carcinoid syndrome (flushing, diarrhea, bronchospasm)

Answer 787

selective agonist of the 5HT1a receptor and is a safe and effective treatment for generalized anxiety disorder. It has no muscle relaxant or anticonvulsant properties anti-anxiety agent useful in pts with a history of abuse of anti-anxiety drugs due to its reduced potential for abuse compared to benzodiazepines

Answer 788

common complication thought to involve decreased micturition reflex activity, decreased contractility of the bladder detrusor, and/or increased vesical sphincter tone. This condition may be treated with a muscarinic agonist (bethanechol) or an a1 blocking drug

Answer 789

proton pump inhibitors (ex. lansoprazole) block the final common pathway of gastric acid secretion from the parietal cells, which is stimulated by acetylcholine, histamine, and gastrin

Answer 790

Turner syndrome is associated with congenital anomalies of the aorta, and the most common defect is a bicuspid aortic valve. A nonstenotic bicuspid aortic valve can manifest as an early systolic, high-frequency click over the right second interspace Bicuspid aortic valves are at risk for stenosis, insufficiency, and infection

Answer 791

nitrates can lead to a reflex tachycardia by causing a relative hypotension that the body responds to with catecholamine release this adverse effect can be prevented by administering beta-adrenergic blockers with nitrates

Answer 792

Although very effective and capable of producing quick symotom relief, glucocorticoids are usually used only for short-term therapy of rheumatoid arthritis due to their unfavorable side effect profile methotrexate is the preferred disease-modifying tx for most pts with moderate-severe rheumatoid arthritis, response takes weeks to occur

Answer 793

series of gene mutations that leads to the development of colon adenocarcinoma includes 3 stages: progression from normal mucosa to small polyp (APC mutation) increase in the size of the polyps (K-ras mutation) malignant transformation (p53 mutation)

Answer 794

Pancytopenia (decreased erythrocytes, leukocytes, and platelets) is common in pts with systemic lupus erythematosus. It frequently occurs due to the formation of autoantibodies against blood cells (type II hypersensitivity). In contrast, lupus nephritis is caused by immune complex deposition within the glomerulus (type III hypersensitivity)

Answer 795

Neutropenia is seen in about 1% of pts on ticlopidine and typically presents with fever and mouth ulcers. Rare, but serious complication - CBC should be monitored biweekly for the first 3 months

Answer 796

= flow velocity * cross sectional area = constant

Answer 797

can cause upper respiratory infection, meningitis, and meningococcemia immunity against these bacteria is provided by antibodies against their polysaccharide capsules the meningococcal vaccine contains capsular polysaccharides from major serotypes of N meningitidis and induces production of protective anticapsular antibodies

Answer 798

most common in children and usually affects the metaphysis of long bones due to the slower blood flow and capillary fenestrae in this region without proper treatment, the infection can progress to chronic suppurative osteomyelitis

Answer 799

[absolute risk control - absolute risk treatment] _________ | absolute risk control

Answer 800

infectious disease caused by various species of Shigella S. sonnei is the most common (~80%) etiological agent in the US Shigella invades the GI mucosa by first gaining access to M cells in Peyer's patches in the ileum through endocytosis Shigella subsequently lyses the endosome, multiplies, and spreads laterally into other epithelial cells, causing cell death and ulceration with hemorrhage and diarrhea

Answer 801

often involves cranial nerve III caused by predominantly central ischemia, which affects the somatic nerve fibers but spares peripheral parasympathetic fibers symptoms include ptosis, a 'down and out' gaze and normal light and accommodation reflexes

Answer 802

facultative intracellular gram-negative bacillus that can cause a systemic infection symptoms include high fever, cough, confusion, and diarrhea the most common lab abnormality seen with Legionella pneumonia is hyponatremia, and sputum Gram stain often shows many neutrophils but few or no new organisms

Answer 803

typically presents as blue-violet or brownish skin plaques on the extremities and mucous membranes of HIV-positive patients this tumor arises from primitive mesenchymal cells and is strongly associated with HHV-8

Answer 804

most often caused by N gonorrhoeae and C trachomatis If urethritis, cervicitis or PID is not treated they can lead to scarring of the fallopian tubes and infertility or ectopic pregnancy must treat for both - 3rd generation cephalosporin (ceftriaxone) + azithromycin or doxycycline

Answer 805

contain transmembrane domains composed of alpha helices with hydrophobic amino acid residues such as valine, alanine, isoleucine, methionine and phenylalanine

Answer 806

as the follicular phase advances, a progressive rise in serum estradiol is seen. High levels of estrogen in the late follicular phase have a positive feedback effect on LH production, causing a very high LH level, known as 'LH surge' Progesterone secretion increases following ovulation with the formation of corpus luteum

Answer 807

results when serous fluid accumulates within the tunica vaginalis the tunica vaginalis is embryologically derived from the peritoneum; when it remains in communication with the peritoneum, a communicating hydrocele results

Answer 808

most often occurs secondary to nondisjunction during maternal meiosis I. A severe condition, trisomy 13 is strongly associated with cleft lip and palate, polydactyly, rocker-bottem feet and holoprosencephaly

Answer 809

In pts with cryptorchidism, the seminiferous tubules become atrophic and hyalinized as a result of temperature-induced damage, resulting in a significantly depressed sperm count as well as decreased inhibin levels. Hormonal function of Leydig cells is usually not impaired. Thus, secondary sexual characteristics and sexual performance are normal. Should be surgically corrected early in life to prevent damage to the seminiferous tubules and decrease the pts risk of testicular cancer

Answer 810

oral anti-diabetic agents that work by decreasing proximal tubular resorption of glucose, thereby promoting urinary glucose loss recommended to monitor serum creatinine before and after initiating therapy with SGLT2 inhibitors

Answer 811

has several permissive effects example: increases vascular and bronchial smooth muscle reactivity to catecholamines (synergistic / additive effects happen when 2 drugs have similar actions)

Answer 812

distinguished from nephrogenic DI by administration of antidiuretic hormone isolated damage to the posterior pituitary gland produces only transient central DI, while damage to the hypothalamic nuclei will cause permanent central DI

Answer 813

will cause a decrease in cortisol synthesis via inhibition of 11-B-hydroxylase In pts with an intact hypothalamic-pituitary-adrenal axis, this will cause a reactive increase in ACTH, 11-deoxycortisol and urinary 17-hydroxycorticosteroid levels

Answer 814

male neonates are born with feminized external genitalia that typically masculinize at puberty

Answer 815

Sex hormones promote both growth and epiphyseal plate closure; hence, precocious puberty may result in a shorter stature, despite an initial growth spurt gigantism is caused by excessive pituitary production of growth hormone, these pts achieve enormous heights because, unlike excessive sex steroids, excessive IGF-1 does not lead to premature closure of the epiphysis

Answer 816

Protein kinase A is primarily responsible for the intracellular effects of the G-protein / adenylate cyclase second messenger system some hormone receptors that use this mechanism include the TSH, glucagon, PTH and beta-adrenergic receptors

Answer 817

usually a benign (90%) tumor arising from the adrenal medulla typically produce episodic symptoms diagnosis is confirmed by the measurements of urine and plasma catecholamines and catecholamine metabolites such as metanephrines

Answer 818

results from deficiency of galactose-1-phosphate uridyl transferase; this defect is the most common cause of galactosemia. The clinical features of this illness include vomiting, lethargy and failure to thrive soon after breastfeeding is begun

Answer 819

Pts with noncoronary atherosclerotic disease, diabetes mellitus or chronic kidney disease are at the same risk of cardiovascular events (MI, stroke) as pts with known coronary heart disease coronary heart disease is the most common cause of death in pts with DM

Answer 820

protons dissociate from amino acids (giving it a negative charge) when the pH exceeds the pKa associated with each given proton

Answer 821

neuromuscular hyperexcitability can become clinically apparent when serum calcium levels are

Answer 822

the acute effects of corticosteroids on the CBC include: increased neutrophil count, and decreased lymphocyte, monocyte, basophil and eosinophil counts the increase in neutrophil count results from 'demargination' of neutrophils previously attached to the vessel wall

Answer 823

activate PPAR-gamma, which is the nuclear receptor that alters the transcription of genes responsible for glucose and lipid metabolism TZDs exert their glucose-lowering effect by decreasing insulin resistance

Answer 824

impairs fatty acid transport into mitochondria, restricting ketone body production (ex. acetoacetate)

Answer 825

seen in pts with chronic renal failure these pts have an elevated serum PTH, accompanied by normal to low serum calcium levels, and high serum phosphorus levels circulating 1,25-dihydroxy vitamin D levels are low due to the deficiency of 1-alpha-hydroxylase, an enzyme that resides in the kidneys

Answer 826

fluid retention, with resultant weight gain and edema, is a common side effect of thiazolidinedione therapy this excess fluid can exacerbate underlying congestive heart failure

Answer 827

associated with oligomenorrhea, obesity, hirsutism, and polycistic ovaries increased risk for developing endometrial adenocarcinoma and type 2 DM

Answer 828

Lipoic acid is a cofactor for several mitochondrial enzymes: PDH (deficiency results in lactic acidosis), a-ketoglutarate DH and branched-chain ketoacid DH (deficiency results in maple syrup urine disease)

Answer 829

ACTH is the major trophic hormone of the zona fasciculata and reticularis, whereas the zona glomerulosa is primarily regulated by angiotensin II prolonged ACTH stimulation causes hyperplasia of the zona fasciculata and reticularis, resulting in excessive cortisol production (Cushing syndrome)

Answer 830

hypercalcemia: 'bones, stones, groans and psychiatric overtones' Osteitis fibrosa cystica is the most characteristic skeletal manifestation of primary hyperparathyroidism this condition presents with bone pain, subperiosteal erosions affecting the phalanges of the hand, a 'salt and pepper' skull and brown tumor bone cysts

Answer 831

adrenal crisis: hypotensive, tachycardic, hypoglycemic, hx consistent with adrenal insufficiency (vomiting, weight loss, hyperpigmentation) cortisol is essential to cardiovascular and metabolic adaptations during stress the ideal treatment for pts in adrenal crisis is administration of stress-dose corticosteroids response to vasopressors in the presence of adrenal insufficiency is generally suboptimal (b/c glucocorticoids have a permissive effect on vasoconstriction)

Answer 832

features of thyrotoxicosis, tenderness over the thyroid gland, increased ESR and a markedly-reduced radioactive iodine uptake are diagnostic of granulomatous thyroiditis mixed, cellular infiltration with occasional multinucleate giant cells are characteristic histologic findings

Answer 833

Sulfonylurea or meglitinide abuse and insulinoma cause increased insulin, c-peptide, and pro-insulin levels the only way to distinguish between insulinoma and sulfonylurea or meglitinide abuse is by screening the urine or blood for hypoglycemic agents

Answer 834

activates glycolysis by inducing phosphofructokinase-1 and inhibits gluconeogenesis by inhibiting fructose 1,6-bisphosphate high concentrations of fructose 2,6-bisphosphate also decreases the gluconeogenic conversion of alanine to glucose fructose 2,6-bisphosphate concentration is regulated by a bifunctional enzyme composed of phosphofructokinase-2 and fructose 2,6-bisphosphatase

Answer 835

Beta-blockers ameliorate the symptoms of thyrotoxicosis by decreasing the effect of sympathetic adrenergic impulses on target organs they also decrease the rate of peripheral conversion of T4 to T3

Answer 836

results from an autosomal recessive mutation in the proteins responsible for normal flagellar and ciliary structure and function (ex. dynein, assembly proteins) clinical manifestations include situs inversus, chronic sinusitis, bronchiectasis, and infertility

Answer 837

serial measurements of B-hCG should be performed following evacuation of a hydatidiform mole persistently elevated or rising levels may signify the development of an invasive mole or choriocarcinoma

Answer 838

characterized by sheets of pleomorphic, high-grade cells with central necrosis

Answer 839

produces a low-grade fever, a maculopapular rash with cephalocaudal progression, and posterior auricular and suboccipital lymphadenopathy most adult women pts develop polyarthritis and polyarthralgia as sequelae congenital rubella syndrome is associated with sensorineural deafness, cataracts and cardiac malformations (PDA)

Answer 840

increases insulin resistance, stimulates proteolysis and lipolysis, and inhibits gluconeogenesis maternal insulin resistance results from increased secretion of hPL, placental growth hormone, estrogens, progesterone and glucocorticoids

Answer 841

Pts with anorexia nervosa often experience amenorrhea due to loss of pulsatile secretion of gonadotropin-releasing hormone (GnRH) from the hypothalamus it is important to remember that the defect in anorexia-related amenorrhea begins in the hypothalamus, not the pituitary or ovaries low estrogen levels over the long-term can result in osteoporosis if left untreated

Answer 842

reduces blood pressure and cardiac work, which is beneficial in the acute treatment of myocardial ischemia however, when noncardioselective agents are used, adverse effects like bronchoconstriction (dose-dependent) may be seen

Answer 843

can be caused by bronchial asthma, chronic bronchitis, and/or emphysema secondary to smoking often can cause hypoxia sufficient to stimulate increased erythropoietin production by the cortical cells of the kidney

Answer 844

anaphylaxis is the result of widespread mast cell and basophil degranulation and the release of preformed inflammatory mediators, including histamine and tryptase Tryptase is relatively specific to mast cells and can be used as a marker for mast cell activation

Answer 845

The high-affinity IgE receptor (FceRI) is found on the surface of mast cells and basophils and normally binds the Fc portion of circulating IgE antibodies Cross-linking of multiple membrane-bound IgE antibodies by a multivalent antigen results in aggregation of the FceRI receptors, causing degranulation and the release of preformed mediators (histamine, tryptase) that initiate an allergic response

Answer 846

``` Carbamazepine Phenobarbital Phenytoin Rifampin Griseofulvin ```

Answer 847

``` Cimetidine Ciprofloxacin Erythromycin Azole antifungals Grapefruit juice Isoniazid Ritonavir (protease inhibitors) ```

Answer 848

ex. phenobarbital induce the hepatic microsomal enzymes, increasing warfarin metabolism and reducing its anticoagulant activity

Answer 849

CO binds to hemoglobin with much higher affinity than O2, thus preventing oxygen binding to hemoglobin. It also reduces oxygen unloading from hemoglobin in the tissues (left shift) CO poisoning does not affect the PaO2 (partial pressure of oxygen dissolved in plasma) and does not precipitate methemoglobinemia

Answer 850

HUS affects young children and manifests with acute renal failure, microangiopathic hemolytic anemia and thrombocytopenia associated with E coli O157:H7 and Shigella characteristic laboratory abnormalities include decreased RBC count, hematocrit and platelet count and increased bleeding time, LDH, BUN and creatinine

Answer 851

Nevirapine, efavirenz, delavirdine antiretroviral drugs that do not require activation via intracellular phosphorylation

Answer 852

acute hepatitis with mild or subclinical symptoms that eventually completely resolve

Answer 853

can cause hemolytic-uremic syndrome (HUS) rare condition affecting mostly children under 10, the strain of E coli is most commonly contracted after eating undercooked ground beef

Answer 854

cause contralateral spastic rigidity, hyperreflexia, and paresis they can affect any part of the pyramidal motor system, including the corticospinal tracts of the spinal cord, the medulla, pons and midbrain, the internal capsule, and the precentral gyrus (primary motor cortex) internal capsule stroke: pure motor weakness, contralateral arm, leg and lower face

Answer 855

The nitrogen atoms in the urea molecule are derived from NH3 and aspartate in the urea cycle Carbamoyl phosphate synthetase I (CPS I) is the rate-limiting enzyme in the urea cycle reaction and is activated by N-acetylglutamate

Answer 856

the IVC is formed from the union of the right and left common iliac veins at he level of L4-L5. The renal arteries and veins lie at the level of L1. The IVC returns venous blood to the heart from the lower extremities, portal system, and abdominal and pelvic viscera

Answer 857

due to a defect in fibrillin, an extracellular glycoprotein that is abundant in the zonular fibers of the lens, the periosteum and the aortic media (component of the microfibrils that form a sheath around elastin fibers) the different locations of fibrillin production explains the varied clinical manifestations of Marfan's syndrome

Answer 858

decreased esophageal body peristalsis and poor relaxation of the LES on manometry are typical for achalasia Achalasia presents with progressive dysphagia, chest pain, food regurgitation and aspiration Barium swallow shows a dilated esophagus and a 'bird beak' deformity of the LES

Answer 859

autosomal dominant disorder that results in a gain-of-function mutation in the FGFR3 gene Most individuals affected by AD disorders are heterozygous and have a 50% chance of transmitting the mutation to their offspring

Answer 860

aspiration of hydatid cysts is generally inadvisable, as the spilling of cyst contents within the peritoneum can cause anaphylactic shock The most common cause is tapeworm, Echinococcus granulosus (endemic regions like australia, sheep and dogs)

Answer 861

For a purified RNA molecule to induce viral protein synthesis in a host cell, it must be able to act directly as mRNA using the host's intracellular machinery for translation. Therefore, in general, purified single-stranded positive-sense RNA (like rhinovirus) can be infectious, single stranded negative sense or double stranded RNA is not

Answer 862

causes an increase in cerebrospinal fluid (CSF) neutrophil count and protein concentration as well as a decrease in CSF glucose Streptococcus pneumoniae is a leading cause of community acquired pneumonia, otitis media and meningitis in adults. S. pneumo appears on Gram stain as lancet-shaped, Gram-positive cocci in pairs

Answer 863

is responsible for almost half of all UTIs in sexually active young women. Staphylococcus saprophyticus belongs to coagulase negative staphylococci and is unique among these because it is resistant to novobiocin

Answer 864

highly contagious disease that presents with an intensely pruritic rash (usually gets worse at night) in the flexor surfaces of the wrist, lateral surfaces of the fingers, and the finger webs Pts usually have excoriations with small, crusted, red papules scattered around the affected areas diagnosis is confirmed by skin scrapings from excoriated lesions that show mites, ova, and feces under light microscopy

Answer 865

Mesolimbic-mesocortical - regulates behavior - schizophrenia association Nigrostriatal - coordination of voluntary movements - Parkinsonism Tuberoinfundibular - controls prolactin secretion - hyperprolactinemia

Answer 866

Nitroglycerin and Isosorbide dinitrate undergo considerable first-pass metabolism in the liver when taken by the oral route. Interestingly, isosorbide mononitrate is nearly 100% bioavailable when taken by the oral route

Answer 867

One major pathway that regulates the RAAS involves the beta-adrenergic receptor pathway the beta-adrenergic pathway is mediated through sympathetic stimulation of beta-1 receptors located on juxtaglomerular cells Beta adrenergic blockers like propranolol inhibit renin release by blocking the beta-1 receptor mediated pathway thus, beta adrenergic blockers can also reduce angiotensin I, angiotensin II, and aldosterone levels Since beta-blockers do not affect ACE activity, they do not affect bradykinin levels

Answer 868

chronic, low-intensity mood disorder that responds well to antidepressant medications symptoms are less severe than those of major depressive disorder, but they must be present for at least 2 years before the diagnosis can be made [major depressive: SIGECAPS = sleep disorder, interest defecit, guilt, energy defecit, concentration defecit, appetite disorder, psychomotor retardation or agitation, suicidality]

Answer 869

aldosterone antagonist commonly used in treating class III and IV heart failure pts structurally similar to steroids, spironolactone can cause endocrine effects including gynecomastia, decreased libido and impotence. Gynecomastia occurs in ~10% of pts Eplerenone is a newer and more selective aldosterone antagonist that may produce less endocrine effects

Answer 870

autoimmune insulitis (infiltration of islets by inflammatory cells) with progressive beta cell loss is the most common cause insulin resistance accompanied by relative insulin deficiency is the main cause of diabetes mellitus type 2

Answer 871

Irreversible ischemic injury to the brain tissue results in liquefactive necrosis the infarcted central nervous system tissue is eventually replaced with a cystic astroglial scar in other organs, lethal ischemic injury results in coagulative necrosis

Answer 872

Minute ventilation = tidal volume * respiratory rate (includes dead space ventilation) Alveolar ventilation = respiratory rate * (tidal volume - dead space volume)

Answer 873

for long term relief eradicate the H pylori infection of the gastric mucosa with antibiotic therapy (2 of: metronidazole, tetracycline, amoxicillin, clarithromycin; + PPI)

Answer 874

Aldosterone excess will cause hypertension, hypokalemia, metabolic alkalosis and depressed renin. [Alternatively, hypoaldosteronism is the cause of type IV renal tubular acidosis] Aldosterone antagonists such as spironolactone or eplerenone can be used as medical therapy for Conn's syndrome

Answer 875

coronary artery disease is the underlying etiology in most cases of sudden cardiac death typically, an acute plaque change will result in acute myocardial ischemia, which may precipitate ventricular fibrillation. Cardiac arrhythmia is the most common cause of death in MI patients during the prehospital phase ventricular failure is the most common cause of death during the in-hospital phase other late-onset, potentially lethal complications include ventricular rupture and mural thrombosis with thromboembolism

Answer 876

typically affects the gastric antrum and is usually the result of H. pylori infection of the gastric mucosa associated with an increased risk of gastric adenocarcinoma and MALT lymphoma

Answer 877

rare, autosomal dominant condition characterized by the presence of capillary hemangioblastomas in the retina and/or cerebellum, as well as congenital cysts and/or neoplasms in the kidney, liver and pancreas

Answer 878

peripheral nervous system tumor syndrome | neurofibromas, optic nerve gliomas, Lisch nodules and cafe au lait spots

Answer 879

marked, noe sided kidney atrophy is suggestive of renal artery stenosis (RAS) occurs in elderly individuals due to atherosclerotic changes in the intima or in women of childbearing age due to fibromuscular dysplasia. Hypertension and an abdominal bruit are present

Answer 880

Urinary acid excretion occurs primarily in the form of NH4+ and titratable acids (H2PO4-) in metabolic acidosis, urinary pH decreases due to increased excretion of free H+, NH4+ and H2PO4- bicarbonate is completely reabsorbed from the tubular fluid in acidotic states

Answer 881

Autosomal recessive disorder characterized by a deficiency of the sphingomyelinase enzyme and resultant accumulation of sphingomyelin. Pts present in infancy with loss of motor skills, hepatosplenomegaly, hypotonia and a cherry-red macular spot Foamy histiocytes are the classic finding on tissue histology. Death usually occurs before age 3

Answer 882

acute inflammation of the gallbladder that is initiated 90% of the time by obstruction of the gallbladder neck or cystic duct

Answer 883

arises within the cerebral hemispheres and frequently crosses the midline. Foci of necrosis and hemorrhage are seen on macroscopic exam most common primary cerebral neoplasm in adults (next 2 are meningioma and acoustic neuroma)

Answer 884

noncaseating granulomas seen on light microscopy of the intestine are characteristic of Crohn's disease and resemble sarcoid granulomas [Granulomas are not seen in ulcerative colitis] Other classic findings in Crohn's disease: linear or serpiginous ulcerations, a cobblestone appearance of the mucosa, and a transmural inflammatory infiltrate

Answer 885

neurotoxicity is the dose-limiting side effect of vincristine therapy this toxicity results from failure of microtubule polymerization in neuronal axons other notable adverse effects classically associated with chemotherapeutic agents include: pulmonary fibrosis and flagellate skin discoloration with bleomycin use congestive heart failure with doxorubicin hemorrhagic cystitis with cyclophosphamide

Answer 886

depensd on the function of hepatic P450 oxidases and is dose-dependent drugs that induce hepatic microsomal enzymes (phenobarbital/barbituates, carbamazepine, rifampin, griseofulvin, chronic alcohol) enhance phenytoin metabolism and decrease its serum concentration

Answer 887

isoniazid, cimetidine, macrolides, azole antifungals, grapefruit juice

Answer 888

arises secnodary to an increase in the number of trinucleotide repeats within the FMR1 gene on the X chromosome typical clinical features: mental retardation, facial deformities and macroorchidism

Answer 889

A significant mismatched defect on ventilation-perfusion scan is a specific finding for a pulmonary embolism, which is usually the result of a deep vein thrombosis and part of a continuum of the same disease, known as pulmonary thromboembolism

Answer 890

the carcinoid syndrome can cause predominantly right-sided endocardial fibrosis which may progress to pulmonic stenosis and/or restrictive cardiomyopathy the severity of carcinoid disease correlates with plasma levels of serotonin and urinary excretion of the serotonin metabolite, 5-hydroxyindoleacetic acid

Answer 891

Small vessel leukocytoclastic angiitis associated with IgA and C3 deposition most common in children 3-11, related to recent infection most children present with palpable skin lesions, with or without abdominal pain and arthralgias usually self-limiting, but observe carefully because glomerulonephritis and end-stage renal disease are possible complications

Answer 892

slowest in the AV node, fastest in the Purkinje system conduction speed of the atrial muscle is higher than that of the ventricular muscle

Answer 893

Arginine - Nitric oxide Arginine + Aspartate - urea Glycine + succinyl CoA - Heme Glycine + Arginine + SAM - creatine Glutamate - GABA, Glutathione Glutamate + aspartate - pyrimidines Glutamine + aspartate + glycine - purines Histidine - histamine Tyrosine - dopamine, epinephrine, norepinephrine, thyroxine, melanin Tryptophan - serotonin, melatonin, niacin

Answer 894

Nitric oxide is synthesized from arginine by nitric oxide synthase as a precursor of nitric oxide, arginine supplementation may play an adjunct role in the treatment of conditions that improve with vasodilation, such as stable angina

Answer 895

all sensory pathways except olfaction have relay nuclei in the thalamus the VPL receives impulses from the spinothalamic and medial lemniscus pathways the VPM from the trigeminal and gustatory pathways the lateral and medial geniculate bodies are relay nuclei for the visual and auditory pathways (respectively)

Answer 896

the posterior cerebral artery branches off the basilar artery and supplies cranial nerves III and IV and other structures in the midbrain It also supplies the thalamus, medial temporal lobe, splenium of the corpus callosum and occipital lobe the most common finding with posterior cerebral artery stroke is contralateral homonymous hemianopia, often with macular sparing

Answer 897

Left ventricular leads in biventricular pacemakers course through the coronary sinus, which resides in the atrioventricular groove on the posterior aspect of the heart

Answer 898

ACE inhibitors cause renal failure by altering renal hemodynamics ACE inhibition results in efferent arteriole dilatation (reduced angiotensin II), thereby decreasing glomerular pressure and renal perfusion for pts dependent on efferent arteriole constriction to maintain renal perfusion (those with renal artery stenosis), ACE inhibitors can be detrimental causing acute renal failure or complicating existing renal disease

Answer 899

does not have a cytotoxic effect itself, the presence of viral HBsAg and HBcAg on the cell surface stimulate the host's cytotoxic CD8+ T lymphocytes to destroy infected hepatocytes

Answer 900

adaptive change that occurs in response to chronic epithelial irritation smoking induces squamous bronchial metaplasia, while long-standing reflux results in columnar metaplasia of the distal esophagus (Barrett's) both these conditions increase the risk of malignancy (= premalignant)

Answer 901

Sympathetic output to the viscera is transmitted through two-neuron units that synapse on noradrenergic receptors of the target organs exceptions: adrenal glands are directly innervated by preganglionic neurons using acetylcholine sweat glands are innervated by a 2 neuron efferent system where both neurons use acetylcholine

Answer 902

potent Na channel blockers that exhibit strong use-dependence by prolonging the QRS duration to a greater extent at higher heart rates Class III antiarrhythmics block the repolarizing potassium current and demonstrate reverse use-dependence (the slower the heart rate, the more the QTc interval is prolonged)

Answer 903

Infection of the sacral sensory ganglia with a double-stranded DNA virus is likely to eventually result in a recurrent, painful genital rash (genital herpes) secondary to reactivation of the latent herpes simplex virus (HSV-2)

Answer 904

low doses of dopamine stimulate D1 receptors in the renal and mesenteric vasculature resulting in vasodilation and increased blood flow to these sites higher doses of dopamine increase cardiac contractility by stimulation of beta-1 adrenergic receptors, even higher doses produce generalized vasoconstriction by an alpha-1 adrenergic effect

Answer 905

infection is a common cause of inflammatory gastroenteritis and can be acquired from contaminated food or domestic animals. The diarrhea is inflammatory and is accompanied by fever, abdominal pain and tenesmus associated with Guillain-Barre syndrome

Answer 906

alcohols function by disorganizing the lipid structure in membranes, causing them to be leaky, and by denaturing cellular proteins they are bactericidal, tuberculocidal, fungicidal and virucidal but do not destroy bacterial spores

Answer 907

can develop during chemotherapy for cancers with rapid cell turnover (poorly differentiated lymphomas and leukemias), substantial tumor burden, or high sensitivity to chemotherapy characterized by hyperphosphatemia, hypocalcemia, hyperkalemia and hyperuricemia prevention of tumor lysis syndrome often involves hydration and the use of hypouricemic agents such as allopurinol or rasburicase

Answer 908

polymicrobial, B. fragilis (anaerobic gram-neg bacillus) and E coli are the most prominent organisms isolated

Answer 909

HLA-B27 spondyloarthropathy that can occur following infection by Chlamydia, Campylobacter, Salmonella, Shigella or Yersinia asymmetric large joint arthritis with sterile synovial fluid on joint aspiration

Answer 910

ensure that all pregnant women have been vaccinated with the tetanus toxoid, to allow transfer of protective IgG antitoxin antibodies across the placenta to the fetus

Answer 911

small, red, cutaneous papules common in aging adults they do not regress spontaneously and typically increase in number with age light microscopy of these lesions shows proliferation of capillaries and post-capillary venules in the papillary dermis

Answer 912

maturing erythrocytes lose their ability to synthesize heme when they lose their mitochondria mitochondria are necessary for the first and final 3 steps of heme synthesis

Answer 913

important clue to cardiac tamponade defined as a decrease in the systolic pressure of 10 mmHg or more during inspiration as compared with the pressure during exhalation

Answer 914

Aspirin irreversibly inhibits COX-1 and COX-2 COX-2 is an inducible enzyme that is normally undetectable in most tissues except in the case of inflammation

Answer 915

can cause disulfiram-like efects when combined with alcohol used to treat giardiasis, trichomonas vaginitis and bacterial vaginosis

Answer 916

1-9% of caucasians worldwide are heterozygote carriers of factor V Leiden, which is modified to resist activated protein C the resulting hypercoagulable state predisposes to deep vein thromboses, which are the source of most pulmonary emboli

Answer 917

autosomal dominant results from red blood cell cytoskeleton abnormalities; most commonly, spectrin and ankyrin defects the definitive test for spherocytosis is a positive osmotic fragility test (lysis of blood cells when intubated in hypotonic saline)

Answer 918

bacterial mRNA can be polycistronic, meaning that one mRNA codes for several proteins example: bacterial lac operon, which codes for the proteins necessary for lactose metabolism by E. coli; the transcription and translation of these bacterial proteins is regulated by a single promoter, operator, and set of regulatory elements

Answer 919

common problem in the treatment of pain mechanism may involve increased phosphorylation of opioid receptors, increased adenylyl cyclase activity, or increased NO levels activation of NMDA receptors by glutamate is believed to enhance morphine tolerance by increasing phosphorylation of opioid receptors and increasing nitric oxide levels NMDA receptor blockers, like ketamine, block the actions of glutamate and effectively decrease morphine tolerance

Answer 920

all nitrates, both long and short acting, are most commonly associated with the side effects of HEADACHE AND FACIAL FLUSHING these reactions occur because of the vasodilatory properties of nitrates in the meninges and skin

Answer 921

clomiphene estrogen receptor modulator that decreases the negative feedback inhibition on the hypothalamus by circulating estrogen and thereby increases gonadotropin production (FSH, LH and ovulation)

Answer 922

high arterial blood pH, HCO3- and pCO2 vomiting/nasogastric suctioning and thiazide/loop diuretic use cause volume and Cl- depletion, resulting in metabolic alkalosis that is saline-responsive in contrast, hyperaldosteronism leads to metabolic alkalosis that is saline-unresponsive determining the pts volume status and measuring the urinary chloride concentration can help to identify the cause of metabolic alkalosis

Answer 923

presents clinically with hypotension, tachycardia, and an elevated central venous pressure that produces jugular vein distension (JVD) heart sounds may be muffled on cardiac auscultation and systolic blood pressure may drop more than 10mmHg on inspiration (pulsus paradoxus)

Answer 924

presents with gradually progressive dyspnea and bilateral reticulonodular opacities on chest x-ray pulmonary function tests reveal a restrictive pattern and lung biopsy shows patchy interstitial lymphocytic inflammation and fibrosis of the alveolar walls

Answer 925

indicated in non-obstructive urinary retention, paralytic ileus and glaucoma side effects include nausea, vomiting, abdominal cramps, diarrhea, dyspnea and increased secretions

Answer 926

the net number of molecules diffusing across a semipermeable membrane per second is proportional to the molecule's concentration difference across the membrane, the total membrane surface area, and the solubility of the substance. Diffusion is inversely proportional to the total membrane thickness and the molecular weight of the molecule

Answer 927

location of the only serotonin-releasing neurons in the CNS these neurons disseminate widely to synapse on numerous structures in the CNS

Answer 928

responsible for many of the toxic effects observed in meningitis and meningococcemia. Blood levels of LOS correlate closely with morbidity and mortality

Answer 929

common and typically results from trauma to the leg near the head of the fibula signs include 'foot drop' and a characteristic 'steppage gait'

Answer 930

progressively weakening diaphragmatic contractions during maximal voluntary ventilation with intact phrenic nerve stimulation indicate neuromuscular junction pathology (eg, myasthenia gravis) and/or abnormally rapid diaphragmatic muscle fatigue (eg, restrictive lung or chest wall disease)

Answer 931

symmetrical enlargement of the ventriculi is characteristic of communicating hydrocephalus communicating hydrocephalus usually occurs secondary to dysfunction or obliteration of subarachnoid villi (arachnoid granulations) this dysfunction is usually a sequelae of meningeal infection (including tuberculosis meningitis) or subarachnoid/intraventricular hemorrhage

Answer 932

Tolerance to opioid induced constipation and miosis does not readily occur to prevent bowel complications, it is recommended to treat pts prophylactically with adequate fluid intake and daily laxatives

Answer 933

diagnosed by indai ink staining of cerebrovascular fluid main treatment is amphotericin B and flucytosine, followed by long-term fluconazole

Answer 934

can cause hypothyroidism and nephrogenic diabetes insipidus and can accumulate in pts with renal insufficiency Serum thyroid stimulating hormone levels, lithium levels and renal function should be measured routinely

Answer 935

tetrodoxin is a neurotoxin produced by microorganisms associated with the fish binds to voltage-gated sodium channels in nerve and cardiac tissue, preventing sodium influx and depolarization

Answer 936

autosomal recessive mutated gene on chromosome 9 has an increased number of trinucleotide repeats often associated with hypertrophic cardiomyopathy, diabetes mellitus, kyphoscoliosis and foot deformities

Answer 937

indicated for the treatment of bradycardia as it decreases vagal influence on the SA and AV nodes. A common side effect is increased intraocular pressure. It may precipitate acute close-angle glaucoma (unilateral severe eye pain and visual disturbances) in susceptible individuals

Answer 938

presents with a generalized, excruciating headache, classically described as 'the worst headache of my life' usually occurs due to rupture of saccular (berry) aneurysms or arteriovenous malformations Berry aneurysms of the circle of Willis are associated with ADPKD

Answer 939

gains access to the CNS by first colonizing the nasopharynx and subsequently invading the mucosal epithelium and gaining access to the bloodstream through the blood, it spreads to the choroid plexus, gains access to the CNS through the blood-brain barrier, and initiates an inflammatory process

Answer 940

(also known as methylmalonic aciduria) results from a defect in the isomerization reaction that transforms methylmalonyl CoA to succinyl CoA, prior to succinyl CoA entering the TCA cycle

Answer 941

can produce contralateral homonymous hemianopia with macular sparing

Answer 942

ptosis, a downward and laterally deviated eye, impaired pupillary constriction and accommodation, and diagonal diplopia the most dreaded cause of CN III palsy is an enlarging intracranial aneurysm

Answer 943

can cause receptive aphasia, characterized by well-articulated, nonsensical speech paired with a lack of language comprehension (Wernicke - Word salad) wernicke's area is located in the auditory association cortex within the posterior portion of the superior temporal gyrus in the dominant temporal lobe the MCA (middle cerebral artery) supplies Broca's area (superior division) and Wernicke's area (inferior division)

Answer 944

occurs after administration of inhalation anesthetics and/or succinylcholine to genetically susceptible individuals treated with dantrolene that blocks ryanodine receptors and prevents release of Ca into the cytoplasm of skeletal muscle fibers

Answer 945

typically occurs 2-8 weeks after exposure to high-risk drugs such as anticonvulsants (eg, phenytoin, carbamazepine), allopurinol, sulfonamides (eg, sulfasalazine), and antibiotics (eg, minocycline, vancomycin) patients typically develop fever, generalized lymphadenopathy, facial edema, diffuse skin rash, eosinophilia and internal organ dysfunction

Answer 946

inhibition of uterine contractions (tocolysis) is a result of B2 adrenergic receptor stimulation Alpha-1 receptor stimulation causes contraction of the ocular pupillary dilator muscle, resulting in mydriasis (pupillary dilation)

Answer 947

5' to 3' exonuclease activity in addition to its 5' to 3' polymerase and 3' to 5' exonuclease activities this 5' to 3' exonuclease activity is used to remove the RNA primer (which initiates DNA polymerization) and to remove damaged DNA

Answer 948

inhibitor of MAO type B and can prevent MPTP-induced damage of dopaminergic neurons used clinically to delay the progression of Parkinson disease Many neurologists favor the use of combinations of selegiline, anticholinergics and amantadine until they no longer provide control of symptoms. Only then is levadopa/carbidopa introduced

Answer 949

commonly located at the cerebellopontine angle and arise from cranial nerve (CN) VIII pts may have ipsilateral sensorineural hearing loss/tinnitus and vertigo (CN VIII), loss of facial sensation (CN V), and facial paresis (CN VII) bilateral acoustic neuromas are associated with neurofibromatosis type 2

Answer 950

facultative intracellular, produces a very narrow zone of beta-hemolysis on blood agar, shows tumbling motility at 22C and can be cultured at temperatures as low as 4C. Intact cell-mediated immunity is essential for the elimination of the bacterium from the body. Neonates up to 3 months of age are especially vulnerable as their cell-mediated immunity is not yet fully developed

Answer 951

typically occur between an amino acid and a-keto acid the amino group from the amino acid is transferred to the a-keto acid, and the a-keto acid in turn becomes an amino acid pyridoxal phosphate (vit B6) serves as a cofactor in amino acid transamination and in decarboxylation reactions

Answer 952

causes accumulation of phenylalanine in body fluids and the CNS homozygous infants are normal at birth but gradually develop severe intellectual disability and seizures if left untreated hypopigmentation of the skin, hair, eyes and catecholaminergic brain nuclei is also frequently seen

Answer 953

present in soil and pigeon droppings the yeast is transmitted via the respiratory route, with the lungs as the primary site of entry in immunocompromised pts, lung infection may be followed by dissemination of C. neoformans, often into the CNS

Answer 954

closely resembles the clinical presentation of Friedereich ataxia Vit E is a lipid soluble vitamin that has antioxidative properties degeneration of the spinocerebellar tracts, dorsal column of the spinal cord and peripheral nerves

Answer 955

most common viral cause of aseptic meningitis coxsackievirus, echovirus, poliovirus Poliovirus can cause lower motor neuron injury in addition to meningitis, especially in non-immunized individuals from endemic areas

Answer 956

common cause of inherited mental retardation X-linked and affects males pts have mental retardation, dysmorphic facial features (large jaw, large protruding ears) and macroorchidism

Answer 957

can be poorly formed during embryonic development resulting in first arch syndrome abnormalities include malformation of the mandible, maxilla, malleus, incus, zygoma, vomer, palate and temporal bone the first arch is associated with the trigeminal nerve

Answer 958

presents with irritability, poor feeding, increased head circumference and enlarged ventricles on CT long-term sequelae of hydrocephalus include lower extremity spasticity due to stretching of the periventricular pyramidal tracts, visual disturbances, and learning disabilities

Answer 959

neurofibrillary tangles and amyloid plaques

Answer 960

chemoprophylaxis of meningococcal meningitis prescribed to all close contacts of any pt who has active disease within 2 weeks of diagnosis vaccine is typically not used for post exposure prophylaxis

Answer 961

the influx of extracellular calcium into the presynaptic terminal Ca++ influx into the nerve terminal occurs following neuronal depolarization and opening of voltage-gated calcium channels

Answer 962

bind to muscarinic receptors on endothelial cells and promote release of NO (EDRF) NO activates guanylate cyclase and diminishes endothelium calcium concentration this produces vasodilatation

Answer 963

as opposed to serotonin syndrome, the neuroleptic malignant syndrome is distinguished clinically by an absence of myoclonus and by the presence of rigidity Dopamine agonists (bromocriptine) and/or direct muscle relaxants (dantrolene) have been used to decrease mortality rates associated with the neuroleptic malignant syndrome, but there is no way to prevent it most commonly associated with Haloperidol (used to treat agitation)

Answer 964

regulates circadian rhythm processes light information and relays it to other hypothalamic nuclei and the pineal gland to modulate body temperature and the production of hormones such as cortisol and melatonin Melatonin supplementation is recommended for the treatment of insomnia associated with jetlag

Answer 965

increase levadopa availability to the brain Entacapone and tolcapone are the currently available COMt inhibitors

Answer 966

scheduled daytime naps and psychostimulants (eg, modafinil) for daytime sleepiness

Answer 967

used for simple partial, complex partial, and generalized tonic-clonic seizures acts by blocking voltage-gated sodium channels in neuronal membranes can cause bone marrow suppression, so blood counts should be reviewed often

Answer 968

oculomotor nerve (CN III), ophthalmic nerve (CN V1) branches, trochlear nerve (CN IV), abducens nerve (CN VI) and superior ophthalmic vein enter the orbit via the superior orbital fissure

Answer 969

characterized by uncomfortable sensation in the legs accompanied by an urge to move the legs worse at rest and when falling asleep dopamine agonists are the preferred medication (ropinirole, pramipexole)

Answer 970

profound cerebral hypoperfusion may lead to global cerebral ischemia (ischemic-hypoxic encephalopathy) watershed infarcts occur between the zones of perfusion of the anterior, middle and posterior cerebral arteries these infarcts typically appear as bilateral wedge-shaped strips of necrosis over the cerebral convexity, parallel and adjacent to the longitudinal cerebral fissure

Answer 971

limited scleroderma (CREST)

Answer 972

bullous pemphigoid

Answer 973

pemphigus vulgaris [positive Nikolsky sign - The eraser is placed on your skin and gently twirled back and forth --> a blister will form in the area, usually within minutes. A positive result is usually a sign of a blistering skin condition. People with a positive sign have loose skin that slips free from the underlying layers when rubbed. The area beneath is pink and moist, and usually very tender.]