Week of March 30

Question 1

What causes the urinary incontience in normal pressure hydrocephalus

Answer 1

Triad: ataxic gait and urinary incontinence, then dementia

Expanded ventricles place traction on cortical efferent and afferent fibers (corona radiata) which disrupts the paraventricular pathways that transmit impulses from cortex to sacral micturition center. Later, lack of inhibition from cerebral cortex leads to frequent and uncontrolled micturtion (i.e. urge incontinence); no sensation of bladder fullness/control over bladder fxn. Voluntary relaxation of urethral sphincter remains intact. 17

Question 2

How is the micturition reflex (urination) regulated (review of 17)

Answer 2

1. Sacral micturtion center: responsible for bladder contraction; parasympathetic fibers travel from S2-S4 ventral whit ematter within pelvic nerves and stimulate cholinergic receptors in bladder wall
2. Pontine micturition center: relaxation of external urethral sphincter with bladder contraction during voiding
3. Cerebral cortex: inhibits sacral micturition center.

Question 3

When do you use chi-square test

Answer 3

To test 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 patients that experience each outcome is recorded in a 2X2 table. 1184

Question 4

Atypical lymphocytes observed in the peripheral smears of patients with infectious mononucleosis represent what?

Answer 4

Activated CD8+ cytotoxic T-lymphocytes (appear much larger than lymphocytes with abundant cytoplasm, an eccentrically-placed nucleus, and a cell membrane that apperas to conform to the borders of neighboring cells) which function to destroy virally-infected B-lymphocytes. 7643

NOTE: IM characterized by sore throat, malaise, LAD, myalgias, splenomegaly, and fever. After infecting pharyngeal mucosa and tonsillar crypts, EBV gains access to bloodstream where it preferentially infects B-lymphocytes by binding to CD21 cell surface receptor.

Question 5

If migration of neural crest cells to the intestine is interrupted during the final week, which organ is most likely to be affected?

Answer 5

The arrest of migration of NCC causes Hirschsprung disease, in which a segment of colon is deprived of ganglion cells. NCC give rise to ganglion cells of the submucosal (Meissner) and myenteric (auerbach) plexi of the bowel wall. Since NCC migrate caudally, the RECTUM is always involved in Hirschsprung disease. The abscence of ganglion cells in colonic wall causes affected segment to be narrowed b/c it cannot relax. 330

Question 6

Fracture of the 12th rib on the left side will most likely damage which structure and why?

Answer 6

The distal tip of the left 12th rib can be displaced into the retroperitoneum when fractured because both the 11th and 12th ribs are “floating ribs” that re not bound to anterior rib cage by cartilage. The 12th rib overlies the parietal pleura medially and kidney laterally. 1700

Question 7

What caues shingles and how does it appear on LM

Answer 7

Herpes zoster (shingles) develops d/t reactivation of VZV (enveloped dsDNA virus) in the dorsal root ganglia (sensory neurons). On LM intranuclear inclusiosn in keratinocytes and multinucleated giant cells (positive Tzanck smear). Skin biopsy would show acantholysis (loss of intercellular connections) of keratinocytes and intraepidermal vesicles. 1042

Question 8

What are the aortic and pharyngeal arch derivatives

Answer 8

During embryonic development, the head, neck, and upper thorax region develop from a set of arches known as pharyngeal arches. Each arch is associated with a CN and aortic arch.

• First: part of mxillary artery; CN V
• Second: stapedial artery (regresses); CN VII. Gives rise to the muscles of facial expression.
• Third: common carotid artery, proximal internal carotid; CN IX. Gives rise to parts of the hyoid bone as well as stylopharyngeal muscle.
• Fourth: Left (aortic arch), Right (right subclavian artery); superior laryngeal branch of vagus (CN X). Gives rise to the muscles of the pharynx and soft palate.
• Sixth: pulmonary arteries, ductus arteriosus; recurrent laryngeal branch of vagus (CN X). Gives rise to most of the muscles of the larynx.

Question 9

PDA aortic arch derivative and symptoms

Answer 9

Ductus arteriosus is a derivative of the **sixth aortic arch. **Vessel usually closes after birth d/t decreased PGE2 levels and increased O2 consumption (can close with Indomethacin = PGE2 inhibitor). Patency results in L-R shunt that can cause LV volume overload and HF Sx (failure to thrive, resp distress). Continuous “machinery-like” murmur and palpable thrill over left intraclavicular region d/t turbulent blood flow thru PDA. 1751

Question 10

Homeobox-containing genes code for which protein types?

Answer 10

Code for DNA-binding transcription factors (i.e. transcription regulators) which aler the expression of genes involved in morphogenesis.

Question 11

A significant increase in blood oxygen saturation between the 2 right-sided vessels or chambers indicates what?

Answer 11

Left-to-right shunt. If such an oxygen step-up occurs b/w the RA and RV, a VSD is most likely which produces a holosystolic murmur that is loudest over the left mid-sternal border. 187

Question 12

Triad of hemolytic anemia, hypercoaguability (e.g. hepatic vein thrombosis and Budd-Chiari), and pancytopenia suggest what?

Answer 12

Paroxysmal nocturnal hemoglobinuria (PNH) which results form an acquired mutation in the PIGA gene that causes abscence of the glycosylphosphatidylinositol (GPI) anchor and associated deficiency of CD55/59 complement inhibitor proteins –> complement-mediated hemolysis. 897

Question 13

What are the features of vitamin A overuse

Answer 13

Acute: n/v, vertigo, blurred vision

Chronic: alopecia, dry skin, hyperlipidemia, hepatoxicity, HSM, visual difficulities. Papilledema when present is suggestive of cerebral edema in setting of benign intracranial HTN (pseudotumor cerebri)

Teratogenic: microcephaly, cardiac anomalies, fetal death (esp. in first trimester). 1048

Question 14

What is one of the renal complications of tumor lysis syndrome?

Answer 14

Occurs when tumors with high cell turnover are treated with chemo. Lysis of tumor cells causes intracellular ions, such as K+ 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 normally acidic environment of distal tubules and collecting ducts. Prevention includes urine alkalinization and hydration, as high urine flow and high pH along nephron prevents crystallization and uric acid precipitation; allopurinol can alo reduce uric acid production. 1050

Question 15

How can you diagnose a Strongyloides stercoralis infection?

Answer 15

Becgins following skin penetration by filariform (infectious) larva and can be dignosed by finding rhabditiform (noninfectious) larvae in the stool. Rhabditiform larvae can mature into filariform larva in the human GI tract, precipitating an autoinfeciton cycle –> hyperinfection syndrome characterized by massive dissemination of organism with multiorgan dysfunction and spetic shock. Pruritic, erythematous, linear streaks (larva currens) may occur on thighs and buttocks as teh larva migrate subcutaneously alway from the perianal region. Treatment: Ivermectin. 8873

Question 16

What fungus can manifest with nodules that spread along lymphatics and commonly infects immunocompotent individuals?

Answer 16

Sporothrix schenckii: dimorphic fungus that cuases subcutaneous mycosis; transmitted by thorn prick.

Inital lesion is a reddish nodule that later ulcerates. Biopsy would reveal a granuloma. From the site of inoculation, the fungus spreads along the lymphatics forming subcutaneous nodules and ulcers. 270

Question 17

Is unfractionated heparin or LMWH (enoxaparin) better at inactivating thrombin

Answer 17

Both unfractionated heparin and LMWH can bind to antithrombin to increase its activity against Factor Xa. Only unfractionated heparin is able to bind to antithrombin and thrombin to allow antithrombin to inactivate thrombin. 2132

Question 18

What is the treatment and contraindication of treatment for an ST-segment elevation in inferior leads.

Answer 18

Diagnostic of inferior MI which are often d/t blockage of the RCA, the artery responsible for SA and AV node perfusion. Thus, inferior MIs are often associated with bradycardia.

Atropine blocks vagal influence on the SA and AV nodes and is effective in increasing HR in such patients. A common SE is increased intraocular pressure. In the eye, atropine causes mydriasis, resulting in narrowing of the anterior chamber angle and diminished outflow of aqeuous humor –> angle-closure glaucoma, with sx of unilateral severe eye pain and visual distrubances (e.g. halos). 1322

Question 19

Segmental transmural inflammation with fibrinoid necrosis is most characteristic of what?

Answer 19

PAN which presents wtih malaise, weight loss, abdominal pain, and melena. Associated with hepatitis B infection.

Question 20

What is the most common vasculitis from antibiotic use?

Answer 20

Microscopic polyangiitis (leukocytoclastic or hypersensitivity angiitis) which affects small vessels only. A type III immune reaction is the pathogenesis, and the antigen is often a medication (commonly penicillin)

Question 21

Small cell carcinomas stain for which types of markers?

Answer 21

Tumor cells express neuroendocrine markers (e.g. neuron-specific enolase, chromogranin, synaptophysin, neurofilaments) and contain neurosecretory granules in the cytoplasm.

Question 22

How do males with classic, non-salt-wasting 21-hydroxylase deficeincy present?

Answer 22

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

Treatment of congential adrenal hyperplasia involves low doses of exogenous corticosteroids to suppress excessive ACTH secretion and reduce stimulation of the adrenal cortex. 2081

Question 23

How does acute hemorrhage into the pituitary gland (pituitary apoplexy) present?

Answer 23

Usually associated with a pre-existing pituitary adenoma. It presents acutely with severe HA, CN involvement (e.g. bitemporal hemianopsia, opthalmoplegia), and signs of meningeal irritation. Typically, chronic sx related to the pituitary tumor (e.g. HA, decreased libido) are present for months before the actual hemorrhage event.** CV collapse** can occur d/t ACTH deficeincy and subsequent adrenocortical insufficeincy. Tx: glucocorticoids (to prevent life-threatening hypotension). 225

Question 24

What drugs are used in the treatment of hirsutism

Answer 24

Hirsutism occurs d/t increased testosterone secretion or increased conversion of testosterone to DHT via 5-alpha-reductase. Sironolactone has anti-androgenic properties and is used for treatment of hirsutism. Other drugs include antiandrogens flutamide (inhibits binding to testosterone receptors) and finasteride (5-alpha-reductase inhibitor). 656

Question 25

Presence of capillary hemangioblastomas in teh retina and/or cerebellum, as well as congenital cysts and/or neoplasms in kidney, liver and pancreas

Answer 25

VHL disease. Also at increased risk of RCC, which cna be bilateral

Question 26

Describe Sturge Weber Syndrome Presentation

Answer 26

Cutaneous facial angiomas as well as leptomeningeal angiomas. Skin involvement overlies the opthalmic (V1) and maxillary (V2) distributions of the trigeminal nerve. Associated with mental retardation, seizures, hemiplegia, and skull radiopacities. Skull radiographs may show characteristic “tram-track” calcifications.

Question 27

Tuberous Sclerosis Presentation

Answer 27

AD. Kidney, liver, and pancreatic cysts. CNS involvment includes cortical and subepedymal hamartomas. Cutaneous angiofibromas (Adenoma sebaceum), visceral cysts, and a vairety of other hamartomas, as well as renal angiomyolipomas and cardiac rhabdomyomas. Seizures are a major complication.

Question 28

What can be used to prevent the AE of cisplatin

Answer 28

Cisplatin: forms ROS that can form DNA crosslinks. SE is nephrotoxicity –> prevent with amifostine and establishment of a chloride diuresis (via IV saline) to keep cisplatin in a nonreactive state.

NOTE: Leucovorin (folinic acid) used in treament of MTX overdose. Dexrazoxane is an iron-chelating agent that can help prevent anthracycline-induced (i.e. doxorubicin) cardiotoxicity.

Question 29

The avid uptake of bromodeoxyuridine (thymidine analog) by a tumor reflects what

Answer 29

Thymidine is a nucleotide used for DNA synthesis; therefore nucleotide uptake occurs in the S phase of the cell cycle. Reflects the high number of tumor cells in the S phase (preparing to divide) that are present in a tumor. A high proliferation rate suggests a high tumor grade and, therefore, a poor prognosis. 616

Question 30

Describe hormone secretion in lung cancers

Answer 30

SCC: PTHrP and hypercalcemia

Small Cell: Cushing Syndrome and SIADH

Question 31

What cells participate in CNS repair after ischemic infarction

Answer 31

During first week after an acute stroke, CT will show ischemic area to be hypodense. Microscopically, neurons display signs of irreversible damage during first 48h (“red neurons”). Neutrophils initially move into the area, followed by microglia 3-5d after onset of ischemia.

As the neurons disintegrate, there is extensive phagocytosis of myelin degradation products by microglia, causing an abundance of lipids to be seen in the cytoplasm. 20

Question 32

What are the most common causes of osteomyelitis in patients with Sickle Cell

Answer 32

Patients have functional asplenia as a result of multiple infarctions of the spleen –> prone to infection by encapsulated organisms. Both Staph aureus and Salmonella (high fever, exquisite thigh pain, bacteremia d/t nonlactose-fermenting, oxidase-negative organism) are common causes of osteomyelitis. 1137

Question 33

Contact dermatitis, granulomatous inflammation, the tuberculin skin test and the Candida extract skin reaction are all examples of what?

Answer 33

Delayed-type HSR, where antigen is taken up by dendritic cells and presented to CD4+ T-lymphocytes on MHC class II. These stimulates TH-lymphocytes (usually of the TH1 lineage) then release release IFN-y to cause recruitment and stimulation of macrophages. Take days to reach their peak activity. 544

Question 34

Hallucinations of recently deceased relatives in children is…

Answer 34

part of a normal grief reaction and may not be indicative of major psychiatric illness. 10465

Question 35

How is essential tremor treated?

Answer 35

Slowly progressive symmetric postural and/or kinetic tremor that most commonly affects upper extremities. First-line treatment is the nonspecific beta-adrenergic antagonist propranolol. 1946

Question 36

The most important steps for prevention of cenral venous catheter infections are what?

Answer 36

Proper hand washing, full barrier precautions during insertion of central line, chlorhexidine for skin disinfection, avoidance of femoral insertion site, removal of cath when no longer needed. 8282

Question 37

Describe concentrations of substances as fluid runs along the proximal tubule.

Answer 37

The concentrations of PAH, creatinine, inulin, and urea increase as fluid runs along the proximal tubule, while the concentrations of bicarbonate (actively reabsorbed d/t activity of carbonic anhydrase), glucose, and AAs decrease. 1617

Question 38

A liver mass associated with increased AFP is a typical presentation associated with what

Answer 38

HCC which is strongly associated with HBV infection and often preceded by HBV-induced cirrhosis. Integration of viral DNA into the genome of host hepatocytes triggers neoplasic changes. Other risk factors for HCC include HCV, alcoholic cirrhosis, aflatoxins, and hemochromatosis. 822

Question 39

Describe drug-induced liver injury

Answer 39

Inhaled anesthetics (e.g. halothane) can be associated with a highly lethal fulminant hepatitis that cannot be distinguished from acute viral hepatitis. In severe cases, extensive HCC damage causes liver to rapidly atrophy and appear **shrunken; **widspread centrilobular necrosis and inflammation of protal tracts. Patients have significally elevated aminotransferase levels d/t massive hpatocellular injury and prolonged prothrombin time (factor VII has shortest half-life) d/t failure of hepatic synthetic function. 369

Question 40

What does PCR require

Answer 40

PCR requires primers that are complementary to the regions of DNA flanking the segment to be amplified (note that while PCR does not require that the sequence of target DNA be known, the flanking sequences must be known in order to make the primers). 2043

Thermostable DNA polymerase, deoxynucleotide triphosphates, and the target DNA template strand are also necessary.

Question 41

What is the presentation of Henoch-Schonlein purpura

Answer 41

Generally affects young children and is classically preceeded by an URI. This IgA-mediated hypersensitivity (leukocytoclastic) vasculitis commonly causes abdominal pain, joint pain, lower extremity palpable purpra and hematuria.

Question 42

What will not be affected by pancreatic insufficiency

Answer 42

Pancreatic amylases, along with salivary and brush border amylases, are required for degradation of polysacchraides into monosaccharides, as polysaccharides cannot be absorbed by the intestinal mucosa. D-xylose is a monosaccharide; thus, its absorption does not require pancreatic enzymes and is not affected by pancreatic insufficinecy. Oral administration of a fixed dose of D-xylose can be used to differentiate between malabosprtion of pancreatic vs. GI mucosal etiology. 1907

Question 43

Explain the Southwestern blot

Answer 43

Used to detect DNA-binding proteins such as transcription factors, nucleases, and histones. The target protein binds to a labeled, dsDNA probe that is homolgous to the protein’s regulatory sequence. c-Jun and c-Fos are nuclear transcription factors that directly bind DNA via a leucine zipper motif; the genes that code for these are protooncogenes. 2044

Question 44

What are interviewing strategies for dealing with patients experiencing intimate parter violence

Answer 44

• Ensure privacy (ask others to leave for interview)
• Nonjudgmental, empathic, open-ended questioning
• No pressure to disclose, report, press charges, leave partner
• Ask patient if she feels safe
• Determine if patient has an emergency safety plan/provide referrals for shelts, domestic violence agency, mental health as needed.

10659

Question 45

Describe how one pathogen increases risk of the other in terms of pneumonia

Answer 45

Patients older than 65 are particuarly prone to developing secondary bacteria PN after influenza infection d/t virally induced damage to the mucocillary clearence mechanisms of the respiratory eptihelium. In order, the pathogens most often responsible for secondary bacteiral pneumonia are Strep pneumoniae, Staph aureus, and H. influenzae.

Question 46

What is the most likely cuase of fatigue and new-onset cardiac murmur in a young adult?

Answer 46

Bacteiral endocarditis. Acute, diffuse, proliferative glomerulonephritis secodnary to circulating immune complexes may complicate BE and can result in acute renal insufficency. 229

Question 47

What are the individual subunits of the hemoglobin molecule structurally analogous to?

Answer 47

If seperated, the monomeric subunits will demonstrate a hyperbolic oxygen-dissociation (compared to the normal sigmoid shape) curve simmilar to that of myoglobin. The partial pressure of oxygen at which 50% of myoglobin molecules are oxygen saturated (P50) is only 1mmHg, which is much lower than the P50 of hemoglobin (26 mmHg). 1413

Question 48

Crescent formation on LM but a lack of immunoglobulins or complement deposits on IM indicates what?

Answer 48

Type 3 RPGN (“pauci immune”): most patients have ANCA in thier serum. This condition is associated with Wegner’s, but it can also be idiopathic. Patients present with renal failure, pulm sx (cough, dyspnea, hemoptysis), and URT sx (epistaxis, mucosal ulceration, chronic sinusitis). 13

Remember: Type I is characterized by anti-GBM antibodies with linear deposits of IgG and C3 on IM; foudn in association wtih Goodpasture syndrome. Type II is immune-complex mediated with a “lumpy bumpy”” granular pattern of staining on IM; can be a complication of poststrep glomerulonephritis, SLE, IgA nephropathy, or HSP.

Question 49

What mediates poison ivy dermatitis

Answer 49

Form of allergic contact dermatitis, which is a type IV HSR mediated primarily by T lymphocytes. Poison ivy/oak/sumac all produce urushiol which causes an immune response when attached to proteins (i.e. a hapten). In urushiol-induced contact dermatitis, CD8 T cells are the primary effector cells and directly destroy keratinocytes expresseing haptenated proteins. It manifests as intesnely pruritic erythematous papules, vesicles or bullae that often form linear patterns. 1133

Question 50

What is the drug of choice for oropharyngeal candidiasis in patients wihtout advanced immunodeficeincy?

Answer 50

Nystatin: polyene antifungal; acts by binding to ergosterol in the fungal cell membrane, cuasing the formation of pores and leakage of fungal cell contents. Not absorbd from GI tract and is adminsterd as an oral “swish and swallow” agent.

Question 51

What is an opioid narcotic that has partial agonist and weak antagonist activity at mu receptors?

Answer 51

Pentazocine, which produces analgesic effects with little to no abuse potential. When used in combo with morphine or other opioids that are selective mu receptor agonists, it can competively inhibit mu receptors and produce antagonistic effects reducing opioid analgesic effects. When given to patients dependent on morphine, withdrawal sx can occur secondary to its antagonistic effect at mu receptors. 774

Question 52

What is the cuase of bilateral loss of pain and temperature sensation

Answer 52

Syringomyelia: formation of a cavity (Syrinx) in the cervical region of the spinal cord which damages the ventral white commissure (area of decussation for fibers of the lateral spinothalamic tract), leading ot bilateral loss of pain and temp sensation that is limited to the affected levels (typcially arms and hnds); distal sensation is preserved. Destruction of the motor neurons in the ventral horsn (due to extension of the syrinx) causes flaccid paralysis and atrophy of the intrinsic muscles of the hand. 503

Question 53

What are patients with Multiple Myeloma at greatest risk of?

Answer 53

AL amyloidosis; amyloid protein is derived from monoclonal immunoglobulin light chaisn, and oftne forms deposits in teh kidneys, heart, tonuge, and nervous system. AL amyloidosis contributes to the developmetn of renal failure in MM. 872

Question 54

What is a common SE of thiazolidinedione (e.g. pioglitazone) therapy?

Answer 54

Exert their glucose-lowering effect by reducing insulin ressitance by bindign to PPAR-gamma. Fluid retention, with resultant weight gain and edema. This excess fluid can exacerbate underlying CHF.

Remember: hypoglycemia can occur with the use of sulfonylureas and insulin.

Question 55

What are the treatments for CHF

Answer 55

Include positive inotropes such as digoxin, beta-adrenegic blockers, ACE-I, and diuretics (loop and potassium sparing). Potassium-sparing diurectics act primarily by antagonizing the effects of aldosterone on the late distal tubule and cortical collecting ducts. 2005

Question 56

Hematogenous ostemyelitis is predominately a disease of…

Answer 56

Children that most frequently affects the long bones. Staph aureus is implicated in most cases secondary to a bacteremic event. Strep pyogenes (GAS) is the second most common cause. 646

Question 57

What is the most common cause of hypothyroidism

Answer 57

Hashimoto’s thyroiditis: mononuclear, parenchymal infiltration wtih well-developed germinal centers is a characteristic histiologic finding. Presence of hypothyroidism (elevated TSH and low T4/T3) and elevated antithyroid peroxidase antibody. 769

Question 58

Why can effective immunity against infection be confered with HCV envelope proteins?

Answer 58

Genetic variation has led to the developmetn of a hypervariable region of the envelope glycoprotein that is especially prone to frequent mutation. There is also no proofreading 3’ –> 5’ exonuclease in the RNA polymerase. Becuase of the variety in the antigenic structure of HCV envelope proteins, the productio of host antibodies lags behind the production of new mutant strains of HCV and effective immunity against infection is not conferred. 44

Question 59

What are the findings of a water deprivation test in a patient wtih primary polydipsia

Answer 59

This is simply excessive (pathologic) water drinking. Significant increase in urine osmolality during water depriviation study and <10% change to vasopressin administration (perhaps d/t deficency in aquaporin channels). Patients will have low serum sodium levels and osmolality. Restriction of water intake normalizes urine output in patients. 212

Question 60

How can you recognize tRNA

Answer 60

Small, noncoding form of RNA that contains unusal nucleosides suchas pseudouridine and thymidine. tRNA has a CCA sequence at its 3’ end that is used as a recognition sequence by proteins, and the 3’ terminal hydorxyl group of the CCA tail is used as the bindign site for the amino acid. 2037

Question 61

What is the major virulence factor for Strep pyogenes?

Answer 61

Protein M: inhibits phagocytosis and complement activation, cytotoxic for neutrophils in the serum, mediates bacterial adherence, and is the target of type-specific humoral immunity tto S. pyogenes. 723

Question 62

What reduces the risk of non-hereditary ovarian and emdoterial cancer?

Answer 62

Oral contraceptives. Multiparity and breast-feeding also decrease the risk of ovarian cancer.

Question 63

What is the prophylaxis treatmetn for the various opportunistic infections of HIV

Answer 63

• P. jiroveci (CD4 <200): TMP-SMX
• Toxoplasma gondii (CD4 <100): TM-SMX
• M. avium and M. intracellulare (CD4 <50): Azithromycin. Marked anemia, HSM, and elevated ALP and LDH levels are more common with MAC than extrapulm TB d/t widespread involvemetn of the RES. In contrast to MTB, MAC grows well at high temps and will exhibit optimum growth at 41C.
• Histoplasma capsulatum (CD4 <150): Itraconazole

1312

Question 64

What accounts for myocardial cells that show prominent intracytoplasmic granules that are tinged yellow-brown?

Answer 64

Lipofuscin is the product of lipid peroxidation, accumulation in aging cells (espeically in the heart and liver of aging or cachetic, malnourished patients)

Question 65

How can you remember X-linked recessive disorders

Answer 65

Be Wise Fools GOLD Heeds Silly HOpe

• Bruton aggamaglobulinemia
• Wiskott-Aldrich
• Fabry Disease
• G6PD Deficeincy
• Ocular Albinism
• Lesch-Nyhan
• Duchenne (and Becker) MD
• Hunter Syndrome
• Hemophilia A and B
• Ornithine Transcarbamylase

Question 66

What are the Trinucleotide Repeat Disorders

Answer 66

X-Girlfriends First Aid Helped Ace My Test

Fragile X = CGG

Friedrich ataxia = GAA

Huntington = CAG

Myotonic dystrophy = CTG

Question 67

What is the disorder in which the DNA of patients are hypersensitive to ionizing radiation?

Answer 67

Ataxia-telangiectasia: AR; results from defect in DNA-repair genes. Sx: cerebellar ataxia (occurs in first years of life d/t cerebellar atrophy), oculocutaenous telangiectasias, repeated sinopulmonary infections, and increased incidence of malignancy. 673

Question 68

Describe the inherited disorders that are caued by deficient DNA-repair enzymes (review of 673)

Answer 68

• Ataxia-telangiectasia: DNA hypersensitivity to ionizing radiation. Nonhomologous end joining (brings together 2 ends of DNA fragments to repair double-strandd breaks) is mutated
• Xeroderma pigmentosum: Defective nucleotide excision repair which prevents repair of pyrimidine dimers b/c of UV light exposure. Causes premature skin aging and increased risk of malignant melanoma and SCC
• Fanconi Anemia: hypersensitivty of DNA to cross-linking agents
• Bloom Syndrome: generalized chromosomal instability. Increased susceptibility to neoplasms.
• HNPCC: defect in DNA mismatch-repair enzymes. Leads to increased susceptibility to colon cancer.

Question 69

Elevated amniotic fluid levels causes which fetal anomaly

Answer 69

Elevated amniotic fluid levels (polyhydramnios) can either be d/t to…

• Decreased fetal swallowing: GI obstruction (e.g. d/t duodenal, esophageal, or intestinal atresia) and anencephaly
• Increased fetal urination: high cardiac output d/t anemia or twin-to-twin transfusion syndrome

Question 70

What is thalamic syndrome?

Answer 70

Vascular lesion of the thalamus (e.g. ischemic or hemorrhagic stroke) results in damage to thalamic VPL and VPM nuclei causing complete contralateral sensory loss. Although there are no motor deficits, proprioception is often profoundly affected and may lead to difficulty ambulating and falls. 2076

Question 71

What are small (5mm) cavities located within the basal ganglia, posterior limb of internal capsule, pons, and cerebellum known as?

Answer 71

Lacunar Infarcts: results from occlusion of small penetrating arteries that supply these structures, most comonly d/t chronic uncontrolled HTN or diabetes.

Causes (2077)

• Lipohyalinosis: destructive vessel lesion with loss of normal arterial architecture, mural foam cells, and, in acute cases, evidence of fibrinoid vessel wall necrosis.
• Microatheromas: accumulation of lipid-laden macrophages within the intimal layer of a vessel. In lacunar infarcts, they cause occlusion of a penetrating artery at or near it origin off parent vessel.

Question 72

Describe the lung volumes adn expiratory flow rates in restrictive lung diseases

Answer 72

Decreased lung volumes and increased expiratory flow rates at the corresponding lung volumes. Expiratory flow is increasd d/t decreased lung compliance (increased elastic recoil; compliane is the change in lung volume for a given change in pressure) and increased radial traction exerted on the conducting airways by the fibrotic lung. 1543

Airflow rate is inversely related to airway resistance. Airway resistance (like vascular) is inversely related to the radius of the conduncting vessel to the fourth power. Thus, as radius of airway increases, the resistance of that airway decreases exponentially. In normal individual, high lung volumes are associated with decreased airway resistance d/t increased radial traction (outward pulling) on conducting airways exerted by the inflated and stretched pulmonary interstitium.

Question 73

What is the main site for digestion vs. absorption of dietary lipids (triglycerides, cholesterol, and phopsholipids)

Answer 73

The duodenum is the main site of digestion of dietary lipids, while the jejunum is the main site of lipid absorption. 1018

Fatty acids, cholesterol and monoacylglycerol diffuse through the brush border membrane of the intesitnal cells without the asistance of transporter proteins. Inside the cell, TGs and cholesteryl esters are reconstructed and combined with proteins to form chylomicrons. Bile acids are necessary for lipid absorption. Cholecystectomy has little effect on lipid digestion and absorption though patients may find it difficulty to eat a large fatty meal b/c they do not have ability to release a large amount of stored bile into the gut.

Question 74

What are the ABX effective against P. aeruginosa?

Answer 74

• Anti-pseudomonal penicillins: ticeracillin, piperacillin
• Cephalosporins: ceftazidime (3rd gen), cefepime (4th gen)
• Aminoglycosides: amikacin, gentamicin, tobramycin
• Fluoroquinolones: cipro, levo
• Monobactams: aztreonam
• Carbapenems: imipenem, meropenem

Question 75

What is the TATA box?

Answer 75

Promoter region that binds transcription factors and RNA polymerase II during the initiation of transcritpion. It is located 25 bases upstream from the beginning of the coding region.

Question 76

What is the common pathologic morphology shared by Takayasu artertis and temporal arteritis

Answer 76

Granulomatous inflammation of the media.

Takayasu and temporal involve arterial vessels of different sizes and locations (aorta and proximal aortic arterial branch involvement vs. more distal carotid artery branch involvment, respectively)

Question 77

What is a diuretic that can be used to treat acute angle-closure glaucoma?

Answer 77

Acetazolamide: inhibits carbonic anhydrase in the proximal tubule, which is responsible for catalyzing rxns necessary for NaHCO₃ reabsorption. Inhibting CA results in enahanced HCO₃^- and water excretion. SE include somnolence, parasthesias, and urine alkalinization; rarely metabolic acidosis, dehydration, hypokalemia and hyponatremia. 682

CA is also found in eyes, pancreas, GI tract, CNS and RBC. In eyes, inhibtion of CA will decrease HCO₃^- and acqueous humor formation

Question 78

What water-soluble vitamin must be replaced after total gastrectomy?

Answer 78

**Parenteral administration of vitamin B12. **

Parietal cells in the body and fundus of the stomach secrete IF (in adition to HCl) which binds to vitamin B12. This complex is then absorbed by enterocytes in the terminal ileum.

Question 79

What is the MOA and mechanisms of resistance to Streptomycin

Answer 79

Aminoglycoside that inhibits protein synthesis by inactivating the small 30S RSU. Mutations that result in altered structure of bacterial ribosomal proteins are responsible for aminoglycoside resistance because they modify the ribosomal binding sites for these drugs.

Other mechanisms of resistance to MTB drugs include decreased activity of bacterial catalase-peroxidase (resistance to isoniazid) and structural alterations of enzymes involved in RNA synthesis such as DNA-dependent RNA polymerase (resistance to rifampin)

Question 80

Primary biliary cirrhosis has similar histologic findings to what other disorder?

Answer 80

PBC: autoimmune destruction of intrahepatic bile ducts and cholestasis. In the pre-cirrhotic stage, interlobular bile ducts are destroyed by granulomatous inflammation (“florid duct lesion”) and heavy lymphocyte-predominant portal tract infiltrate. The simmilarity of these findings to those of graft vs. host disease suggest that immunolgoic injury is responsbile for disease manifestations. 402

Question 81

Episodic HTN, tachycarida, HAs, diaphoresis, pallor or flushing and tremors are important clinical clues for the presence of what?

Answer 81

Catecholamine-secreting tumors (e.g. pheochromocytoma of adrenal medulla). Differential shoudl also include autonimc dysfunction, cocaine abuse, withdrawal from clonidine and beta-blockers, and panic attacks. 933

Question 82

What type of study simultaneously measures exposure and outcome at a particular point in time?

Answer 82

Cross-sectional study (also known as a prevalence study). In other study designs, a certain time period seperates the exposure from the outcome. The major limitation of cross-sectional design is that a temporal relationship between exposure and outcome is not always clear. 1276

Question 83

What is an efective add-on therapy for patients with severe allergic asthma that has been shown to be effective in reducing dependency on both oral and inhaled steroids?

Answer 83

Many asthmatics frequently have allergies as a trigger d/t a high IgE response in the body. Anti-IgE antibodies given as a SC injection (i.e., omalizumab) have been shown to be effective in patients with moderate-to-severe allergic asthma. Omalizumab is a recombinant humanized IgG1 monoclonal antibody that binds with IgE to inhibit the action of IgE with its receptor on mast cells, basophils, and other cell types and descrease the allergic response. 2128

Question 84

What is the main immune mechanisms against Giardia?

Answer 84

Giardia lamblia causes injury to duodenal and jejunal mucosa by adhering to the intestinal bursh border and releasing molecules that induce a mucosal inflammatory response. Secretory IgA, which binds to trophozoites and impairs adherence, is the major component of adaptive immunity against infection. Conditions causign IgA deficeincy predipose patients to chronic giardiasis. 1596

Question 85

Describe the pathway of aqueous humor production

Answer 85

Produced by the epithelial cells of the ciliary body –> excreted into posterior chamber and transferred through the pupil into anterior chamber –> trabecular meshwork through which aqueous humor diffuses into Schlemm’s canal –> episcleral and conjunctival veins. 1363

Question 86

What types of drugs are used to treat Glaucoma?

Answer 86

Chronic eye disease characterized by increased IOP. Both narrow-angle and open-angle can ultimately lead to blindness. Drugs used to treat either decrease production of aqueous humor or increase its outflow. 1363

• Timolol (non-selective BBs): diminish secretion of aqueous humor by ciliary epithleium.
• Acetazolamide: CA inhibitor; decreases aqueous humor secretion by ciliary epithleium
• PGF2a (latanoprost, unoprostone, tavoprost) and cholinomimetics (pilocarpine, carbachol) decrease IOP by increasing outflow of aqueous humor.

Question 87

Trochlear nerve (CN IV) palsy is characterized by what?

Answer 87

Vertical diplopia: most noticeable when the affected eye looks toward the nose, as occurs when reading teh newspaper or walking downstairs.

Question 88

Tissue damage and resultant abscess formation is primarily caused by what?

Answer 88

Lysosmal enzyme release from neutrophils and macrophages. 302

Question 89

What are the stabilizing forces for the various structures of proteins?

Answer 89

• Primary: sequence of AAs linked by covalent peptide bonds.
• Secondary: alpha-helix or beta-sheet; d/t hydrogen bonding
• Tertiary: compact folding of secondary structure; ionic bonds, hydrophobic interactions, H-bonds, and disulfide bonds. Disulfide bonds enhance a proteins ability to withstand denaturation.

Question 90

What disease is associated with C-ANCAs that may target neutrophil proteinase 3?

Answer 90

Necrotizing vasculitis of the upper and lower respiratory tract (causing nasal ulcerations, sinusitis, hemoptysis) and rapidly progressive glomerulonephritis - producing a varaible degree of renal failure - is characteristic of granulomatosis with polyangitis (Wegners). 459

Question 91

What is the preferred method for testing for type 1 and 2 diabetes

Answer 91

Fasting blood glucose (NOT oral glucose tolerance test, which is usually reserved for screenign pregnat women for gestational diabetes)

Question 92

How can you distinguish teh pneumoconiosis that can casue exertional dyspnea nad interstital densities on CXR

Answer 92

• Silicosis: produces eggshell calcifications of hilar nodes and birefringent particles surrounded by fibrous tissues
• Asbestosis: calcified pleural plaques and ferruginous bodies. Interstital pattern of involvement, more prominent in lower lobes.
• Berylliosis and hypersenstiivty pneumonitis: noncaseating granulomas
• Coal miners lung: perilymphatic accumulations of coal dust-laden macrophages

Question 93

What are the four major causes of hypoxemia (low PaO2)

Answer 93

1. Alveolar hypoventiliation or inspiration of air with low pO2 (e.g. at high altitude).
2. Ventilation-perfusion mismatch: poor ventilation of a well-perfused alveoli results in physiologic shunting, leading to an increased A-a gradient (e.g. pneumonia, obstructive pulm disease, pulm embolism)
3. Diffusion impairment: diseases that cuase thickening of the alveolar capillary membranes (E.g. alveolar hyaline membrane diseases). Increased A-a as there is a normal concentration fo O2 in alveoli that cannot be transported into blood.
4. Right-to-left shunting: cyanotic congential heart defects; venous blood bypasses lung and enters arterial circulation, thus decreasing PaO2.

The A-a gradient is normal with alveolar hypoventilation and helps to distinguish it from other forms of hypoxemia. Hypoventilation is common in patients with suppressed central respiratory drive (eg sedative overdose, sleep apnea) or those with disease that decrease the inspiratory capacity (eg myasthenia gravis, obesity). 1582

Question 94

The proximal 1/3 of the uterter recieves its blood supply from what?

Answer 94

Branches of the renal arter. For this reason, this portion of the donor ureter is typically viable after renal transplantation. 1680

Question 95

Describe the drugs that work in the different phases of the cell cycle

Answer 95

• G1: cells prepare the building blocks for DNA synthesis
• S: DNA replication. Topo I and II inhibitors as well as hydroxyurea and some antimetabolites function during this phase.
• G2: DNA is checked for errors; if corrections cannot be made, then apoptosis results unless loss-of-function mutatiosn to the genes controllign this process are present
• M: Division; vinca alkaloids and taxanes are specific for this phase (replicated chromosomes are unablet o align and subsequently unable to segregate into daughter cells), 1893

Question 96

What drug causes mycobacteria to lose acid-fastness and rapidly stop proliferating?

Answer 96

Isoniazid: only active against mycobacteria; inhibits mycolic acid synthesis (mycolic acids are essential for proper cell wall structure as well as the synthesis of virulence factors) –> mycobacteria lose thier acid-fastness and become unable to s ynthesize new cell walls or multiply.

Question 97

What disorders exhibit polygenic inheritance (i.e. influenced by multiple genes)?

Answer 97

• Androgenic alopecia (1725)
• Epilepsy
• Ischemic heart disease
• SCZ
• Gluacoma
• HTN
• Malignancy
• Type II DM

Question 98

How does diabetic CN III mononeuropathy present and what is the cause?

Answer 98

Classically presents with acute onset diplopia. On exam, the affected eye assumes a “down and out” position due to unopposed pull by the superior oblique (CN IV) and lateral rectus (CN VI). Ptosis also occurs d/t to paralysis of the levator palpebrae. Caused by ischemic nerve damage, which predominately involves the core of CN III with relative sparing of the peripheral part. Thus, becuase the component responsible for pupillary constriction and accomodation is located in peripheral aspect of nerve, pupillary size and reactivey is normal. 1060

Question 99

What are the commonc auses of elevated creatine kinase (CK)

Answer 99

Can be the first manifestation of hypothyroidism; esp. if patient presents wtih fatigability, weight gain, proximal muscle weakness, and myoedema (focal mounding of muscle following percusion; d/t slow reabsorption of calcium by the SR).

Other causes include autoimmune diseases (e.g. polymyositis, dermatomyositis), muscular dystrophies, and medications such as HMG-CoA reductase inhibitors.

Question 100

Describe differences between leading and lagging strand

Answer 100

While DNA synthesis always occurs in 5’ to 3’ direction on both strands, the leading and lagging strands are constructed in both the 5’ to 3’ and 3’ to 5’ directions, respectively (i.e. constructed in opposite directions). The laggign strand is synthesized discontinuosuly and is composed of short stretches of RNA primer plus newly synthesized DNA segments (Okazaki fragments). Thus, the lagging strand requires the repetitive action of DNA primase and DNA ligase. 1419

Question 101

Vitiligo is characterized by the loss of…

Answer 101

Loss of melanocytes and complete abscence of melanin pigment. 1110

NOTE: individuals with albinism have melanocytes that do not produce melanin becuase of absent or defective tyrosinase.

Question 102

What stages are primary and secondary oocytes arrested in?

Answer 102

Primary oocytes are completely developed in female embryos by the 5th month of gestation, at which point they are arrested in prophase of meiosis I. Ovarian cycle hormones stimulate the primary oocyte to resume differentation. Prior to fertilization, secondary oocytes are arrested in metaphase of meiosis II.

Question 103

What mutations have been associated wtih early-onset and late onset familial Alzheimer disease

Answer 103

Early-onset familial: both APP and presenilin gene mutations are thought to promote the production of A B-amyloid.

• Amyloid precursor protein (APP) on ch. 21
• Presenilin 1 gene on ch. 14
• Presenilin 2 gene on ch. 1

Late-onset familial: E4 on Apolipoprotein E.

Question 104

Which molecules is most likely involved in mediating the accumulation of pus?

Answer 104

Pus consists of a thin, protein-rich fluid, known as liquor puris, and dead keratinocytes, primarily neutrophils. During infection, macrophages and surrounding endothelial cells release cytokines such as IL-8 that trigger neutrophils to enter the site of infection via chemotaxis, and induces phagocytosis in neutrophils. Other chemotatic agents include n-formylated peptides, LTB4, 5-HETE (leukotriene precursor) and C5a. 8539

Question 105

Describe Cori Disease

Answer 105

D/t debranching enzyme deficeincy, which leads to incomplete glycogen degradation. Alpha-1,6-glucosidic branch points cannot be degraded, so small chain dextrin-like material accumulates wtihin the cytosol of hepatocytes. Patients with this illness present with nonspecific findigns of hypoglycemia, hypertriglyceridemia, ketoacidosis, and hepatomegaly. 1030

Question 106

Describe the difference between efficacy and potency

Answer 106

Efficacy: measure of the maximum pharmacodynamic effect achievable wtih a drug. 1707

Potency: dose of drug that is required to produce a given effect. Drugs that bind their receptors with a higher affinity or are better able to gain access to their target tissues will have greater potency (lower ED50)

Example: among the thiazides, 25mg of HCTZ and 5mg chlorthalidone produce simmilar drops in BP (simmilar efficacy), but chlorthalidone requires a lower dose, or a lower ED50, than HCTZ to cause simmilar effect (higher potency).

Question 107

Compare and contrast indirect vs. direct inguinal hernias

Answer 107

In contrast to femoral hernias, inguinal hernias are located above the inguinal ligament. The inferior epigastric vessels serve as an anatomic landmark that can be used to distinguish between direct and indirect.

Indirect: located lateral to inferior epigastric vessels. Can protrude into the scrotum. Occur d/t failure of processus vaginalis to obliterate, allwoing abdominal contents to protrude through the deep inguinal ring.

Direct: located medially to the inferior epigastric vessels. They do not protrude into the scrotum. Protrude through Hasselbach’s triangle, a weak spot of the anterior abdoinal wall. 418

Question 108

Describe maternal rubella infection

Answer 108

Low-grade fever, maculopapular rash with cephalocaudal progression, and posteior auricular and suboccipital LAD. Most adult women patients develop polyarthritis and polyarthralgia as sequelae. Congential rubella syndrome is associated with sensorineural deafness, cataracts, and cardiac malformations (PDA).

Question 109

Where does the loest osmolarity occur in the renal tubules?

Answer 109

Lowest osmolarity occurs in the DCT.

Dehydration stimulates ADH secretion, which acts on teh collecting ducts to increase their permeability to water. In the presence of ADH, the collecting ducts contain the most concentrated fluid in the nephron, while the TALH and DCT contain the most dilute fluid.

Question 110

If you see a drug that has -NO₂ on it, what is the drug and what part of the CV system is most suceptible to it?

Answer 110

Nitroglycerin: acts primarily as a venodilator. Cardiac workload is decreased b/c blood collects in teh venous system (redistrubiton) thereby decreasing preload –> decreased ventricular wall stress and decreased cardiac oxygen demand; thus treats angina! 137

Question 111

Describe when to suspect autoimmune platelet destruction

Answer 111

Suspect in a patient with ecchymoses, petechiae, and mucosal bleeding without s/sx of TTP/HUS, pancytopenia, marrow failure, or splenomegaly. 1954

Question 112

Describe the appereance of the spleen in Sickle Cell Disease

Answer 112

Repeated splenic infarctions eventually lead to significant scarring, fibrosis, and arophy of the spleen (asplenia). This is typically completed by young adulthood.

Question 113

Why do patients with sickle cell disease develop increased macrocytosis?

Answer 113

Patients with SCD or other hemolytic anemias are predisposed to develop folic acid deficiency becuase of increased erythrocyte turnover. Low folic acid levels impair DNA synthesis, while leaving RNA synthesis unaffected. Cytoplsmic components then accumulate within the slowly dividng erythrocytes, producing cells that are larger than normal (macrocytes).

Question 114

Describe why ACE-I are considered to be the most effective long-term treatment option for patietns with HTN and chronic ischemic myocardial failure

Answer 114

Inhibit the chronic angiotensin II-mediated LV hypertrophy and remodeling that occurs in association wtih myocardial failure. Over time, such remodeling diminishes contractile function.

NOTE: BBs have been shown to improve mortality both in patients with systolic CHF and in patients with MI.

Question 115

What is the serious complication and its manifestations of someone taking ticlopidine?

Answer 115

Neutropenia; presents wtih fever an dmouth ulcers.

Question 116

Describe the presentation of scurvy (i.e. vitamin C deficeincy)

Answer 116

Seen in malnourished, alcoholics, poor, and elderly

Gingival bleeding, petechaie, ecchymoses, and poor wound healing. Perifollciular hemorrhage and coiled (corkscrew) hairs are commonly seen.

Hydroxylation of proline and lysine residues in collgen occurs in RER and requires vitamin C as a cofactor.

Question 117

Describe the effect of epinephrine on its various receptors

Answer 117

Epinephrine increases systolic BP (a1 + b1), increases HR (b1), and either increases (high-dose; a1) or decreases (low-dose; b2) diastolic BP depending on the dose. Pretreatmetn with propranolol eliminates the beta effects of epinephrine (vasodilation and tachycardia), leaving only the alpha effect (vasoconstriction).

Question 118

What are the sx associated with pineal germinomas

Answer 118

Germinomas are found in children and adolescents and show a strong male predominance. Histologically they are simmilar to testicular seminomas. 1261

• Precocious puberty may occur in males and is caused by b-hCG production
• Aqueductal compression by the tumor may lead to obstructive hydrocephalus
• Parinaud sydrome includes paralysis of upward gaze and of convergence - these sx occur d/t compression of the tectal area of the midbrain

Question 119

What does Parvovirus B19 cause in adults

Answer 119

Causes erythema infectiosum (fifth disease) in children and arthritis in adults. Parvovirus arthritis can mimic RA, but is unique in that it is self-resolving. 1896

Question 120

Crohn’s disease is associated with increased activity of which protein?

Answer 120

Increased activity of NFkB, which is responsible for cytokine production. Proposed that the NOD2 mutation linked with Crohn’s disease increases the activity of NFkB, allowing inflammation-inducing intracellular microbes to persist. 135

Question 121

What enrves enter the orbit via the superior orbital fissue

Answer 121

CN III, CN V1 (opthalmic nerve) branches, CN IV, CN VI, and superior opthalmic vein.

NOTE: the sensory limb of the corneal reflex is mediated by the nasociliary branch of the first division of the trigeminal nerve (CN V1). The motor component of the corneal reflex is carried by the temporal branch of the facial nerve (CN VII).

Question 122

Polyuria that resolves with the administratin of vasopressin is likely secondary to what?

Answer 122

Central diabetes insipidus which arises when the posterior pituitary gland fails to release vasopressin in sufficient quanitites.

Normally, vasopressin porduces a V2 receptor-mediated increase in permeability to water and urea at the luminal membrane of the inner medullary collecting duct. The increase in urea reabosprtion corresponds toa decrease in the fractial excretion of urea and a decrease in renal clearence of urea from plasma.

Question 123

What is derived from POMC

Answer 123

Produces beta-endorphins, ACTH, and MSH

Question 124

What do you see on light microscopy with actinic keratoses

Answer 124

Hyperkeratosis (hyperplasia of stratum corneum), parakeratosis (retention of nuclei in the stratum corenum), and atypical keratinocytes with pleomorphic nuclei and multiple mitoses. They do not invade the dermis and are considered to be premalignatn.

Question 125

Describe HSV-1 encephalitis

Answer 125

Predilection for temporal lobe; results from reactivation of latent virus “living” in trigeminal ganglion and the virus’ spread along this nerve into cranial vault. Restricted sx include aphasia (damage of speech areas), olfactory hallucinations (olfactory cortex), and personality changes (amygdala).

Edema and hemorrhagic necrosis of temporal lobes. Eosinophilic intranuclear inclusions (Cowdry type A) are present in glial cells and neurons. Multinucleated giant cells may also be found.

Question 126

What is one way to treat anovulation

Answer 126

Administration of drugs that act like FSH and LH. Treatmetn with menotropin acts like FSH and leads to formation of a dominant ovarian follicle. Ovulation is then induced by administration of a large dose of hCG, which stimulates the LH surge.

Question 127

Describe the events based on time after an MI

Answer 127

• 0-4h: minimal change
• 4-12h: early coagulation necrosis, edema, hemorrhage, wavy fibers
• 12-24h: coagulation necrosis, marginal contraction band necrosis
• 1-5d: coagulation necrosis and neutrophilic infiltrate
• 5-10d: macrophage phagocytosis of dead cells
• 10-14d: granulation tissue + neovascularization
• 2w-2m: collagen deposition/scar formation

Question 128

Distinguish anorexia nervosa vs. bulimia nervosa

Answer 128

Anorexia nervosa

• BMI < 18.5. 2 subtypes: restrictring and binge eating/purging
• Medical complications including osteoporosis, amenorrhea, lanugo or hair loss, enlarged partoid glands (if binge/purge type), hypotension, hypothermia, bradycardia, cardiac atrophy, cardiomyopathy, arrhythmias.

Bulimia nervosa: recurrent binge eating with compensatory behaviors to prevent weight gain; both behaviors must occur at least 2X/week for 3m. Compensatory behaviors are subdivided into purging types (e.g. lax, diuretics, enemas, vomitting) and nonpurging types (excessive excercise, dieting, fasting). Usually of normal weight

Question 129

What is the treatment of choice for Listeria?

Answer 129

Ampicillin, which should always be added to the empiric treatment of meningitis in infants and in immunocompromised adults. It is not sensitive to cephalosporins.

Question 130

Distinguish LA compliance between patients with acute vs. chronic mitral regurgitation

Answer 130

Acute MR: near-normal LA compliance. Therefore they tend to develop marked pulm HTN and pulm edema. May be d/t rupture of chordae, infective nedocarditis with destruction of valve leaflets, ischemia/rupture of papillary muscle, or failure of prosthetic valve.

Chronic MR: valvular dysfxn occurs over time, permitting adaptive dilaatation of LA, thinning of its wall, and an increase in LA compliance –> buffers the regurgitant volume from LV and results inlower elevation of LA pressures as compard to acute MR. Thus, they are less prone to pulm HTN/edema but are more prone to AFib and mural thromboembolism. Can be d/t myxomatous degeneration or MVP. 946

Question 131

What are the normal pressures in the cardiac chambers and pulmonary artery

Answer 131

• RA: 0-8mmHg
• RV: 4-25mmHg
• Pulm artery: 9-25mmHg
• LA: 2-12mmHg
• LV: 9-130mmHg
• Aorta: 70-130mmHg

Question 132

Describe a crossover study

Answer 132

Subjects are randomly allocated to a sequence of 2 or more treatments given consecutively. A washout (no treatment) period is often added between treatmetn intervals to limit the confuding effects of prior treatment.

Question 133

What enzyme deficiency causes a simmilar clinical picture and is pathophysiologically simmilar to GP6D deficeincy?

Answer 133

GP6D deficiency is a defect in the HMP shunt that impairs glutathione reduction d/t failure to produce NADPH.

Glutathione reductase deficeincy causes a similar clinical picture and is pathophysiologically simmilar –> hydrogen peroxide is detoxified by glutathione peroxidase in RBC and glutathione is oxidized in this rxn; regeneration fo reduced glutathione is carried out by glutathione reductase using NADPH as electron donor. 1037

Question 134

Differentiate primary/secondary biliary cirrhosis from primary sclerosing cholangitis

Answer 134

All have same presentation (pruritus, jaundice, dark urine, light stools, hepatosplenomegaly) and labs (increased conjugated bilirubin, increase cholesterol, increase ALP)

Secondary Biliary Cirrhosis: extrahepatic biliary obstruction (gallstone, biliary stricture, chronic pancreatitis, carcinoma of pancreatic head) –> increased pressure in intrahepatic ducts –> injury/fibrosis and bile stasis. Complicated by ascending cholangitis.

Primary Biliary Cirrhosis: AI rxn (more common in middle aged white females)–> lymphocytic infiltrate + granulomas –> destruction of intralobular bile ducts. Increase serum mitochondrial antibodies, including IgM. Associated with other AI conditiosn. Tx: ursodeoxycholic acid.

Primary Sclerosing Cholangitis: concentric “onion-skin” bile duct fibrosis –> “beading” of intra- and extrahepatic bile ducts on ERCP. Hypergammaglobulinemia (IgM). Associated with UC (p-ANCA). Can lead to secondary biliary cirrhosis and cholangiocarcinoma.

Question 135

Intraabdominal infections are characterized by which types of organisms?

Answer 135

B. fragilis (expresses unique surface polysaccharides that have been shown to favor abscess formation) and E. coli are the most common.

Question 136

What are the AE of Lithium?

Answer 136

Tremor, sedation, edema, heart block, hypothyroidism (weight gain, dry skin, hair loss, constipation, bradycardia) polyuria (ADH antagonist causing nephrogenic diabetes insipidus), teratogenesis (Ebstein anomaly.

Excreted almost exclusively by the kidney; most is reabsorbed at the PCT following Na+ reabsorption. Need to monitor renal fxn (BUN + Cr).

Question 137

Blowing holosystolic murmur heard over cardiac apex with radiation to axilla + knee swelling as a child

Answer 137

Mitral Regurgiation as a result of rheumatic heart disease. Rheumatic valve disease typically presents as MR within the first few decades of life. Mtiral stenosis can also occur in rheumatic heart disease, and patients prsenting with such are generally middle aged.

2096 with audio

Question 138

How are Enterococci resistant to aminoglycosides (e.g. gentamicin, streptomycin, etc)

Answer 138

Enterococci produce aminoglycoside-modifying enzymes that transfer different chemical groups (Acetyl, adenyl or phopshate) to the aminoglycoside molecule and therefore impair ABX binding to ribosomal subunits. Acquired resistance mediated by plasmids or transposons. 1000

Question 139

Whats in your differential for a cerebellar tumor in a child?

Answer 139

Most likely a pilocytic astrocytoma or medulloblastoma. These two tumors can be differentiated on brain imaging: pilocytic astrocytomas have both cystic and solid components (cystic with a tumor nodule protruding from wall), while medulloblastomas are always solid.

Pilocytic astrocytomas: Rosenthal fibers (eosinophilic corkscrew fibers); GFAP+

Medulloblastomas: Homer-Wright rosettes (cells around center of fibrils; vs. ependymoma forming perivascular rosette); small blue cells with hyperchromatic nuclei and scant cytoplasm

Question 140

Once glucose is added to a medium, E. coli stops fermenting lactose. Why?

Answer 140

Glucose induced decreased AC activity leads to low intracellular concentration of cAMP –> poor binding of CAP to CAP-DNA binding domain (high cAMP levesl activate CAP which binds cAMP and this complex then binds to a region upstream from the promoter and acts as a positive regulator of lac operon) –> decreased expression of teh structural genes of the lac operon. 1478

NOTE: in lactose containing media –> lactose binds to repressor protein –> repressor protein cant bind to operator region –> increased transcriptoin of lac operon structural genes –> increased utilization of lactose for energy.

Question 141

What is the most potent cerebral vasodilator?

Answer 141

pCO2 - it decreases cerebral vascular resistance leading to increased cerebral perfusion adn increased ICP. Patients with COPD usually have low pO2 (hypoxia) and high pCO2 (hypercapnia). Thus, thier cerebral circulation is most likely to be increased.

Question 142

The MOA of polyethylene glycol is most simmilar to the pathophysiology of which disorder?

Answer 142

Polyethylene glycol is an osmotic laxative. Diarrhea associated wtih lactase deficeincy is also osmotic and occurs d/t acumultion of nonabsorbable lactose in teh intestinal lumen. Magnesium hydroxide (and other magnesium-containing compounds, such as magnesium citrate) is another osmotic lax that is often used.

Question 143

Which antiretroviral drugs do not require activation via intracellular phopshorylation

Answer 143

Nonnucleoside reverse transcriptase inhibitors (NNRTIs) including Efavirenz, Nevirapine, Delavirdine. Bind to reverse transcriptase at site different from NRTIs; do not require phosprylation to be active or compete wtih nucleotides. SE: severe hepatotoxic reactions and life-threatening skin rxns (e.g. SJS, TEN).

Remember: retroviral reverse transcriptase inhibitors prevent synthesis of viral DNA from RNA template.

Question 144

What are teh 3 types of signal receptors utilized by the ANS?

Answer 144

cAMP, IP3, and ion channels. Nicotinic receptors are ligand-gated ion channels that open after bidning ACh. This results in an immediate influx of Na+ and Ca2+ into the cell and an outflux of K+ from the cell.

Question 145

What is recall bias?

Answer 145

Results form inaccurate recall of past exposures by people in the study and applies mostly to retrospective studies such as case-control studies. People who have suffered an adverse event are more likely to recall risk factors than those without advere experiencies.

Question 146

What type of organisms are patients wtih CGD susceptible to?

Answer 146

Results from genetic defect in NADPH oxidase, which noramlly participates in the killing of microbes within neutrophil and macrophage phagolysosomes. Patients develop recurrent bacterial/fungal infections caused by catalase positive organisms:

“You need PLACESS for your cats” - Pseudomonas, Listeria, Aspergillus, Candida, E.coli, S. aureus, Serratia. ALSO Burkholderia cepacia

Question 147

What drugs treat Graves’ opthalmopathy?

Answer 147

High-dose glucocroticoids (e.g. prednisone), which are helpful in decreasing the severity of inflammation and decreasing extraocular volume.

Infiltrative opthalmopathy is d/t edema and infiltration of lymphocytes into the EOM and CT. Retro-orbital fibroblats are stimulates by cytokines released from TH1 cells to produce excessive amounts of GAGs –> increased volume of the retro-orbital tissues.

Question 148

The nerves and vessels supplying the ovary are delivered through what?

Answer 148

Suspensory ligament of the ovary (i.e. infundibulopelvic ligament): connects ovaries to lateral pelvic wall and contains the ovarian vessels. Ligate vessels during oophorectomy to avoid bleeding. Ureter courses retroperitoneally, close to gonadal vessels; at risk of injury during ligation.

• Cardinal ligament: cervix to side wall of pelvis. Contains uterine vessels.
• Round ligament: uterine fundus to labia majora; travels through round inguinal canal.
• Broad ligament: uterus, fallopian tubes, and ovaries to pelvic wall. Contains ovarian, fallopain, and round ligaments of uterus. Mesosalpinx, mesometrium and mesovarium are components.
• Ovarian ligament: medial pole of ovary to lateral uterus. “Ovarian Ligametn Latches to Lateral uterus”

Question 149

What is the epithelium that lines each of the following structures: ovary, fallopian tubes, uterus, cervix, vagina

Answer 149

• Ovary: simple cuboidal
• Fallopian Tubes: simple columnar
• Uterus: simple (pseudostratified) columnar
• Cervix: simple columnar (endocervix), stratified squamous (ectocervix)
• Vagina: stratified squamous non-keratinized

Question 150

What is conversion disorder?

Answer 150

Unconscious manifestation of neurologic symptoms when pathophysiological explanations for the symtoms cannot be found. Symptoms must be neurologic in nature and include blindness, aphonia, weakness, pseudoseizure, anesthesia, gait distrubance, diplopia, adn paralysis. It occurs more commonly in women and often occurs after significant life stress.

Question 151

What measures the probability of being free of a disease if the test result is negative?

Answer 151

NPV: varies with the pretest probability of a disease; a patient with a high probability of having a disease will have a low NPV with a negative test but a patient with a low probability of having a disease wil have a high NPV with a negative test. The prevalence of disease is directly related to the pre-test probaiblity of having the disease and, thus, also affects NPV.

Question 152

What accounts for the mild anemia with Mycoplasma pneumonia

Answer 152

Shares antigens with human erythrocytes, and when teh body mounts a response against these antigens it also lyses RBCs leading to anemia. The antibodies causing the RBC destruction are cold agglutinins.

After the infection has been eliminated and the immune ssytem is not longer activated against M. pneumoniae, the concentration of these antibodies decreases and the anemia spontaneously resolves.

Question 153

What are 3 main causes of UCG hyperbilirubinemia and 4 caues of conjugated hyperbilirubinemia

Answer 153

UCG (indirect) Hyperbilirubinemia

1. Increased bilibrubin production: hemolytic anemia, sickle cell disease, hematoma breakdown
2. Impaired bilirubin uptake and storage: viral hepatitis, drugs (e.g. Rifampin)
3. Decreased UDP-glucuronosyltransferase activity: Gilbert, Crigler-Najjar, neonatal physiologic jaundice

Conjugated (direct) Hyperbilirubinemia

1. Excretion Defect: Dubin-Johnson, Rotor Syndrome
2. Biliary epithelial damage: hepatitis, cirhosis, liver failure
3. Intrahepatic biliary obstruction: primary biliary cirrhosis, sclerosing cholangitis, drugs (chlorpromazine, arsenic), liver fluke
4. Extrahepatic biliary obstruction: pancreatic neoplasms, pancreatitis, cholangiocarcinoma, choledocholithiasis.

Question 154

Rx that prolong QT mnemonic?

Answer 154

Some Risky Meds Can Prolong QT

Sotalol, Risperidone, Macrolides, Chloroquine, Protease inhibitors (-navirs), Quinidine (class Ia and III), Thiazides

Question 155

What is projection?

Answer 155

Immature defense mechanism involving misattribution of one’s unacceptible feelings or impulses to another person who does not actually have them. Seen in patients who lack insight and acknowledgemetn of thier own motivtions and feelings. 1429

Question 156

What does H. influenzae type B capsular material consist of?

Answer 156

Ribosyl and Ribitol phopshate polymer called polyribitol phosphate (PRP). It is the only serotype that contains pentose monosaccharides rather than hexose sugars as the carbohydrate component of the capsule. The PRP capsule prevents phagocytosis and intracellular killing by neutrophils, allowing the organism to invade the vasculature, persist in the blodostream, and spread hematogenously.

Question 157

How do you calculate power of a study?

Answer 157

The power of a study is the ability of a study to detect a difference between groups when such a difference truely exists. Power is related to type II error (beta), which is the probability of concluding there is no difference betwen groups when one truly exists. The formula for power = 1 - beta.

Question 158

What is the reaction of type I interferons (alpha and beta) in response to viral infections

Answer 158

Act on neighboring cells (paracrine signaling), stimulating them to synthesize antiviral proteins and degrade intracellular mRNA and impair protein synthesis. RNase L is an endonuclease which degrades both viral and cellular mRNA. Protein Kinase R functions to phosphorylase and inactivate eIF-2, thereby inhibiting translation initiation. These enzymes become active only in the presence of dsRNA in virally infected cells –> decreased protein synthesis by infected cells. 1468

Question 159

An acute transmural MI marked by ST-elevation and subsequent Q-wave formation is most likely the result of what?

Answer 159

**Fully obstructive thrombus superimposed on a ruptured atherosclerotic coronary artery plaque. **

• S/Sx of an acute transmural MI include severe chest pain not relieved by rest or nitroglycerin, diaphoresis, dyspnea, nausea, lightheadness, and/or palpitations.
• Peaked T waves are the first ECG sign (reflecting localized hyperkalemia), and ST-segement elevation follows within minutes to hours. Within hours to days, Q waves appear in involved leads.

A lesser degree of occlusion by a thrombus superimposed on an acute plaque change would more likely cause unstable angina. A stable atheromatous lesion without an overlying thrombus, but obstructing >75% of the coronary artery lumen, would likely cause only stable angina.

Question 160

What arteries to the recurrent laryngeal and superior laryngeal nerve travel with?

Answer 160

Recurrent laryngeal nerve is a branch of the vagus that loops below the aortic arch on left and below subclavian artery on rigth to provide motor innervation to larynx (all except cricothyroid muscle). This nerve travels with inferior thyroid artery (arises from thyrocervical trunk, a branch of the subclavian artery) and can be injured in surgical procedures of anterior neck (e.g., thyroidectomy).

The superior laryngeal nerve is a branch of vagus that gives off internal and external branches. The superior thyroid artery (branches of the external carotid arteries) course with the external branch of this nerve;

Question 161

What is responsible for the chloride content of erythrocytes being much lower in arterial blood than in venous blood?

Answer 161

Carbonic anhydrase activity within erythrocytes forms bicarbonate from CO2 and water. Many of the bicarbonate ions diffuse out of the RBC into the plasma. To maintain the electrical neutrality, chloride ions diffuse into RBC to take their place –> “chloride shift,” which is the principal cause of high RBC chloride content in venous blood.

Question 162

Heart failure d/t LV diastolic dysfunction is the result of what?

Answer 162

Result of a decrease in diastolic LV compliance (=dV/dP). Restrictive cardiomyopathy, as can be caused by amyloidosis, may cause diastolic dysfunction. 93

NOTE: Infectious myocarditis and cardiotoxic agents including alcohol and doxorubin tend to produce a dilated cardiomyopathy with predominately systolic dysfunction.

Question 163

What is the primary cells responsible for the intense inflammatory response seen in patients with gouty arthritis?

Answer 163

Neutrophils: phagocytosis of urate crystals (negatively birefringent; i.e. monosodium urate crystals) by neutrophils causes the release of various cytokines and inflammatory mediators that lead to further neutrophil activation and chemotaxis.

NSAIDs are first-line for treating acute gouty arthritis, which inhibit prostanoid biosynthesis (e.g. postaglandins, prostacyclin, thromboxanes), exerting a braod anti-inflammatory effect that includes inhibtion of neutrophils. If CI (PUD, renal impairment) treat wtih colchicine, which impairs neutrophil migration and phagocytosis by interfering with MT formation AND decreases tyorsine phopshorylation in response to MSU crystals, resulting in decreased neutrophil activation.

Question 164

What organism is responsible for a STD characterized by initially painless ulcers with later progression to painful inguinal LAD and ulceration?

Answer 164

Chlamydia trachomatis serotypes L1-L3, which cause lymphogranuloma venereum (LGV). Histologically characterized by vhlamydial inclusion bodies in cellular cytoplasm. Tx is doxycycline. If untreated, causes fibrosis, lymphatic obstruction, and anogental stricutres and fistulas.

Question 165

Mnemonic to remember which STD are painful vs. painless

Answer 165

“Some Girls Love Licorice, Fellas Hate Candy”

Syphils, Granuloma inguinale (K. inguinale), Lymphogranuloma vernerum (C. trachomatis) = painLess

painFul = Herpes simplex, Chancroid (H. ducreyi)

Question 166

Distinguish the causes of PAINFUL STDs

Answer 166

Chancroid (Haemophilus ducreyi)

• Multiple and deep ulcers
• Base may have gray to yellow exudate
• Organism often clump in long parallel strands (“school of fish”)

Genital Herpes (HSV 1/2)

• Multiple, small, grouped uclers
• Shallow with erythematous base
• Multinucleated giatn cells and intranuclear inclusions (Cowdry type A)

Question 167

Distinguish the causes of PAINLESS STDs

Answer 167

Granuloma inguinale (donovanosis; Klebsiella inguinale): extensive and progressive, base may have granulation-like tissue; deeply staining gram-negative intracytoplasmic cysts (Donovan bodies) are diagnostic

Syphilis: single, indurated, well-circumscribed ulcer with a clean base; thin, delicate, corkscrew-shaped organisms on darkfield microscopy

Lymphogranuloma venereum (Chlamydia trachomatis): small and shallow ulcers that heal rapidly; intracytoplasmic chlamydial inclusion bodies present in epithelial cells and leukocytes.

Question 168

Supplementation with what cna reduce erythroid precursor cell apoptosis in patients with folate deficeincy

Answer 168

Folate deficeincy inhibits the formation of dTMP, which limits DNA synthesis and promotes megaloblastosis and erythroid precursor cell apoptosis. Becuase thymidine supplementation can moderately increase dTMP levels, it can reduce erythroid precursor cell apoptosis.

Remember: thymidylate synthetase catalyzes the methylation of dUMP to dTMP while converting the folate derivative 5,10-methylene THF to DHF.

Question 169

Abdominal XR with air in gallbladder and biliary tree is suggestive of what?

Answer 169

Gallstone ileus: results from passage of a large gallstone through a cholecystenteric fistula into the small bowel; the resulting communication between the gallbladder and small bowel d/t the fistula allows intestinal gas to enter the gallbladder and biliary tree. There is obstruction of the small bowel at the ileocecal valve whihch leads to s/sx of SBO (abd pain and distention, vomitting, tenderness to palpation, tinkling bowel sounds).

Question 170

Squamous metaplasia of the pancreatic ducts in a patient with CF is most likely d/t what

Answer 170

CF can lead to pancreatic insuffiency, fat malabsorption, and deficeincy of vitamins KADE. Vitamin A maintains orderly differentiation of specialized epithelia, including the mucus-secreting columnar epithelia of teh ocular conjunctiva, respiratory and urinary tracts, and pancreatic adn other exocrine ducts. Avitaminosis A can cause squamous metaplasia of such epithelia to a keratinizing epithelium.

Question 171

Axillary lymph node dissection is ar isk factor for the developmetn of what?

Answer 171

Risk factor for the developmetn of chronic lymphedema involving the ipsilateral arm. Chronic lymphadema prediposes to the developmetn of angiosarcoma (Stewart-Treves syndrome) which is characterized by infiltration of the dermis with slit-like abnomral vascular spaces.

Question 172

When can serum hCG be detected

Answer 172

b-hCG becomes detectable in maternal serum only after the blastocyst successfuly implants. Implanation generally occurs on day 6 after ovulation. Generally, b-hCG is detectable in maternal serum about 8 days after ovulation but can take up to 11 days.

Question 173

Which enzyme functions to remove RNA primers during DNA replication?

Answer 173

Bacterial DNA polymerase I has 5’ to 3’ exonuclease activity, which is used to excise RNA primers (can also function as an excision-repair enzyme). The gaps created after RNA excision are then replaced with DNA in the 5’ to 3’ direction by DNA polymerase I.

Question 174

Explain how vitamin B12 replacement therapy in a patient with atrophic gastritis affects reticulocyte counts, hemoglobin and erythrocyte counts

Answer 174

The rate of effective erythropoiesis increases immediately and immature erythrocytes are released from the bone marow into the bloodstream. The reticulocyte response peaks early during replacement.

Hemoglobin and erythrocyte counts rise more gradually.

Question 175

Explain the effect of TZDs on PPAR-gamma

Answer 175

TZDs 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. Important genes that are altered by PPAR-gamma include: increased adiponectin, increased fatty acid transport protein, increased insulin receptor substrate, increased GLUT-4

Question 176

What would cause weak wrist extension, but intact sensation to the arm?

Answer 176

Radial nerve arises from posterior cord of brachial plexus and innervates muscles of posterior (extensor) compartment of arm. At the lateral epicondyle of humerus (where humerus articulates with radius), radial N. divdes into superficial (sensory to radial half of dorsal hand) and deep branches.

Radial head subluxation can damage the deep branch of the Radial N, causing wrist drop, weakness of the FA and hand extensors, but no sensory deficits.

Question 177

What type of medicine can cause the painful crisis known as biliary colic

Answer 177

Mu opioid analgesics can cause contraction of smooth muscles in the sphincter of Oddi leading to increased pressures in the bile duct and gallbladder –> biliary colic. Present with severe pain and cramping in the RUQ.

Question 178

Where is pulmonary vascular resistance (PVR) lowest at?

Answer 178

At the functional residual capacity. Increased lung volumes increase PVR due to longitudinal stretching of alvolar capillaries by expanding alveoli. Decreased lung volumes also increase PVR due to decreased radial traction from adjacent tissues on the large extra-alveolar vessels. 1620

Question 179

Within the true pelvis, you can palpate the left ureter immediately anerolateral to which structure?

Answer 179

The **internal iliac artery **1804

The gonadal artery and vein cross over the anterior surface of the ureter. The ureters gain access to the pelvis by crossing over teh anterior surface of the common iliac artery near its bifurcation into internal and external. At this point, the ureter lies medial to the gonadal vessels and anterolateral to internal iliac artery. In females the ureter than courses along uterosacral ligament just deep to uterine vessels (water under bridge) before entering bladder.

Question 180

What is the MOA of Diphenoxylate

Answer 180

Opiate anti-diarrheal structurally related to meperidine that binds to mu opiate receptors in the GI tract and slows motility. This drug is combined with atropine at therapeutic doses to discourage abuse.

NOTE that octreotide is helpful for secretory diarrhea.

Question 181

Describe the effects of manuevers on HCM that result in increased murmur intensity

Answer 181

Valsalva (straining phase), abrupt standing (from sitting or supine position), nitroglycerin administration. All fxn to decrease preload. 85

Mechanisms that decrease preload (i.e. venous return) or afterload reduce LV chamber size, which decreases the seperation between the mitral valve and the IVS, increasing obstruction. Manuevers that increase preload or aferload will decrease murmur intesity by increasing LVEDV and lessening the outflow tract obstruction.

Question 182

What is one of the most important viruelnce mechanisms by which Staph epidermidis causes disease?

Answer 182

One of the MCC of infections associated with foreign bodies d/t ability to form biofilms, which fxns as a barrier to ABX penetration and interferes with host defeneses.

MOA: Foreign bodies become coated with host proteins (including fibringoen adn fibronectin) which serve as binding sites for bacteria. After attachment, bacteria multiply and communicate with e/o to induce synthesis of an extracellular polysaccharide matrix that encases the bacteria. Biofilms can disperse individual pathogen “seeds” into bloodstream, which further disseminates infection.

Question 183

What are the biofilm-producing organisms and their common settings?

Answer 183

• Staph epidermidis: prosthetic devices, IV caths
• Strep mutans & sanguinis: dental plaques
• Pseudomonas aeruginosa: cystic fibrosis pneumonia, contact lenses
• Viridans group strep: endocarditis
• Nontypable H. influenza: otitis media

Question 184

Describe the effects of dehydration on RPF, GFR, and FF

Answer 184

Leads to a decrease in RPF and a decrease in GFR. Compensatory activation of the RAAS in response to hypotension leads to constriction of the efferent arteriole to matinain GFR. The FF (GF/RPF) increases in hypovolemia as RPF drops proportionately more than GFR d/t the above compensatory mechanism.

Question 185

What are common consequences of LV infarction

Answer 185

Prolonged, burning substernal pain and ST segment elevation in leads I and V3-V6 is strongly suggestive of anterolateral LV infarction. Consequences of LV infarction include LV failure, cardiogenic acute pulmonary edema, pulm venous HTN (congestion), and transudate of plasma into the lung interstitum and alveoli.

Question 186

Describe the result of a lesion to the optic tract

Answer 186

Produce contralateral homonymous hemianopia and a relative afferent pupillary defect (Marcus Gunn pupil) in the contralateral eye.

Question 187

Descirbe impact of optic nerve damage on light reflex pathway

Answer 187

The afferent limb of the light reflex pathway is the optic nerve; the efferent limb is the parasympathetic fibers of the oculomoter 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 (becuase the motor pathways are intact).

This a common AE of multiple sclerosis.

Question 188

Sx of acute-onset abdominal pain, nausea and confusion. Urine is reddish in color and darkens on standing for 24 hours. IV dextrose improved Sx. Diagnosis?

Answer 188

Acute intermittent porphyria: AD, caused by porphobilinogen deaminase deficeincy. May present wtih abd pain and vomitting, peripheral neuropahty, neuropsychological sx, and reddish-brown urine (NO photosensitity). Treatmetn consists of IV glucose or heme preparations, which downregulate ALA synthetase activity (rate-limiting enzyme of heme synthesis).

Question 189

10% KOH or silver stain shows thick-walled spherules packed with endospores. Can be cultured on Sabouraud’s agar.

Answer 189

Coccidioides immitis: dimorphic fungus; spherules are the tissue form, but exists in teh enviornment in the form of mold (hyphae). Can cause lung disease in immunocompetent and disseminated disease in immunocompromised.

Question 190

Traveler to Great Lakes, Mississippi, or Ohio River basins and contracted pulmonary infection. Diagnosis?

Answer 190

Blastomycosis dermatitidis: may be asymptomatic in an immunocompotent person, but it can also cause a flu-like illness, or cough with sputum production, hemoptysis, dyspnea, and pleuritic chest pain. Pulmonary blasto is characterized by granuloma formation. KOH sputum stain shows round yeast (with single broud-based bud) with thick, double refractive walls. Tx: itraconazole.

Question 191

How can first-generation antipsychotics be classified?

Answer 191

All block D2 receptors (increased cAMP)

Low-potency: more likely to cause non-neurologic side effects such as sedation (histaminergic blockade), orthostatic hypotension (alpha-1 blockade), and anticholinergic SE (cholinergic blockade) Chlorpromazine, Thioridazine (Cheating Thieves are low)

High potency: extrapyramidal sx. Trifluoperazine, Fluphenazine, Haloperidol (Try to Fly High)

Remember the atypicals include: “It’s atypical for old closets to quietly **risper **from **A **to Z” Olanzapine, Clozapine, Quetiapine, Risperidone, Aripiprazole, Ziprasidone.

Question 192

Which enzyme is most likely to function predominately in the nucleolar region of the nucleus?

Answer 192

RNA polymerase 1 which forms rRNA. In addition to transcribing rRNA, the nucleolus is also involved in maturation adn assembly of ribosomal subunits.

Question 193

What would be the lab findings in a patient with ESRD?

Answer 193

Excessive bleeding is d/t accumulation of uremic toxins in circulation which impair platelet aggregation and adhesion, resulting in a qualitative platelet disroder characterized by prolonged bleeding with normal platelet count, PT and PTT. Can be improved with dialysis.

Question 194

Describe optimal breathing rates in disease states

Answer 194

There is an optimal breathing rate at which teh total work of breathing is minimized.

For patients wtih stiff lungs (increased elastic resistance), the work of breathing is minimzed when the RR is high and TV is low. Therefore, rapid and shallow breaths are favored in diseases that increase elastic resistance (e.g. pulmonary fibrosis, pulm edema, ARDS). In contrast, in diseases that cause high airflow resistance (e.g. asthma, COPD), patients breathe at a lower rate (slow, deep breaths) in order to minimize the work of breathing. 8260

Question 195

Compare cherry vs. superficial hemangiomas

Answer 195

Cherry: small, red, cutaneous papules common in aging adults. They do not regres spontaneously and typically increase in number with age. LM shows proliferation of capillaries and post-capillary venules in the papillary dermis.

Superficial (infantile, capillary, strawberry): appear in first few weeks of life. They initally grow rapidly and then freuqently regress spontaneously by late childhood.

Question 196

Describe the manifestation of Graft-verus-host disease

Answer 196

Immunocompetent T-cells within the donor tissue recognize host MHC antigens as foreign and attack them. Both donor CD4+ and CD8+ cells participate in destroying host cells. Skin, liver and GI tract are generally affected more severely.

Acute GVHD develosp within 1 week of the transplant. Liver damage manifests with jaundice and increaed levels of ALT, AST, ALP, and bilirubin. GI tract involvement causes diarrhea, intestinal bleeding, abdominal cramping and/or ileus. In severe cases, there may be skin desquamation.

Question 197

Explain how transamination reactions typically occur

Answer 197

Occur b/w an AA and an alpha-keto acid (e.g. oxaloacetate). The amino group from the amino acid is tranffered to the alpha-keto acid, and the alpha-keto acid in turn becomes an amino acid. Pyridoxal phopshate (Vitamin B6) serves as a cofactor in AA transamination and in decarboxylation reactions.

Question 198

During the intial presentation during the prodromal period of Hepatatis B

Answer 198

Described as “serum sickness-like” during the prodromal period, with patients experiencing malaise, fever, skin rash, pruritus, LAD, and joint pain. Anorexia, nausea, jaundice, and RUQ pain may ensue. Labs: ALT > AST, followed by rises in bilirubin and ALP.

Question 199

How can metastasis of gastric cancer present?

Answer 199

Virchow’s node (metastasis to left supraclavicular sentinel node), Sister Mary Joseph nodule (metastasis to periumbilical region), or as Krukenberg tumor of the ovary (mucin-producing, signet-ring neoplastic cells in the ovarian stroma)

Question 200

Which glycogen storage disorder results in glycogen accumulation within lysosomal vesicles, hepatomegaly, cardiomegaly, maroglossia, hypotonia, and mental retardation?

Answer 200

Pompe Disease (i.e. glycogen storage disease type II), which is due to deficeincy of the enzyme alpha 1,4-glucosidase (acid maltase)

Question 201

How can you distinguish Neuroleptic Malignant Syndrome from Serotonin Syndrome

Answer 201

As opposed to serotonin syndrome, the NMS is distinguished by an abscence of myoclonus and by the presence of rigidity. Dopamine agonists (bromocriptine) and/or direct muscle relaxants (dantrolene) have been used to decrease mortality associated wtih NMS.

For NMS think FEVER: Fever, Encephalopathy, Vitals unstable, Enzymes increased, Rigidity of muscles

Question 202

What is a drug that may lead to severe hypertensive crises with tyramine-containing foods (cheese, sausage, wine)

Answer 202

Phenelzine (MAOI)

Question 203

What is the mnemonic for drugs that can cause drug-induced interstital nephritis (tublointerstital nephritis)

Answer 203

“Pease Note All Drugs that Can Possibly Scar Renals”

Penicillin derivatives, NSAIDs, Allopurinol, sulfa-derived Diuretics, Cephalosporins, PPIs, Sulfonamide antibiotics, Sulfasalazine, Rifampin

Sx: fever, maculopapular rash and sx of acute renal failure 1-3w after beginning treatment with a b-lactam ABX are highly suggestive of AIN. Peripheral eosinophilia, eosinophiluria, IgE are important clues; granuloma formation may be observed.

Question 204

What are the two main manifestations of abnormal rotation and fixation of the midgut early during fetal life

Answer 204

Midgut returns to the abdominal cavity at 10th week of fetal life, simultaneosuly completing a 270 degree turn counterclockwise around the SMA. If this process is abnormal –> intestinal malrotation; cecum is found in the RUQ, fixed with fibrous bands to the second portion of the duodenum. The entire midgut is fixed to the SMA.

Intestinal obstruction (d/t compression of the duodenum by the adhesive bands; bilious vomitting during first days of life) and migut volvulus (intestinal ischemia d/t twisting around the blood vessels)

Question 205

What is the most important biochemical abnormality in Alzheimer Disease

Answer 205

Decreased levels of ACh in the nucleus basalis of Meynert (participates in memory and cognition) and hippocampus (formation of new memories). Diminished activity of choline acetyltransferase in these cerebral structures is the cuase.

Question 206

Which organism is pyrrolidonyl arylamidase (PYR) positive?

Answer 206

S. pyogenes

Question 207

Acute gingivostomatitis (i.e. ulcerative lesions with intranuclear inclusions) in children aged 1-3 years is the most common clinical manifestation of primary infection with which organism?

Answer 207

HSV-1 (enveloped, dsDNA virus)

Question 208

Mycobacteria growth in parallel chains (“serpentine cords”) must strongly correlates with what?

Answer 208

The growth of thick, ropelike cords of mycobacterial organisms in a twisted, “serpentine” pattern is consistent with the presence of cord factor, which is a mycoside. The presence of cord factor correlates with virulence; mycobacteria that do not possess cord factor are not able to cause disease. More specifically, cord factor is responsible for inactivating neutrophils, damaging mitochondria, and inducing release of TNF.

Question 209

Which markers identify osteoclastic vs. osteoblastic activity

Answer 209

Bone-specific alkaline phosphatase reflects osteoblastic activity. Tartate-resistant acid phosphatase, urinary hydroxyproline, and urinary deoxypridinoline reflect osteoclastic activity; urinary deoxypyridinoline is hte most reliable of the three.

Question 210

What causes necrolytic migratory erythema (raised erythematous rash typcially affecting the groin area)

Answer 210

Pancreatic glucagonoma

Question 211

Blanching of a vein into which NE is being infused together with induration and pallor of tissues surrounding the IV site are signs of what?

Answer 211

Signs of NE extravasation and resulting vasoconstriction. Tissue necrosis is best prevented by local injection of an alpha1 blocking drug, such as **phentolamine **–> lead to vasodilation, thus counteracting the alpha1 receptor mediated vasoconstriction of NE.

Question 212

List the features of carcinoid syndrome

Answer 212

Clinical manifestations: arise from enterochromaffin (endocrine) cells of the intestinal mucosa, which produce vasoactive substances such as serotonin (5-HT), bradykinin, and prostaglandins.

• Skin: flushing, telangiectasias, cyanosis
• GI: watery diarrhea, cramping
• Pulm: bronchospasm, dyspnea, wheezing
• Cardiac: valvular fibrous plaques (right > left)

Diagnosis: elevated 24hh urinary 5-HIAA.

Treatment: Ocreotide

Question 213

What can lower the minimum infectious dose of V. cholerae

Answer 213

The minimal infectious dose for cholera infection is usually quite high, given that its very sensitive to gastric acidity. Any condition that decreases acidity (or increases gastric pH), such as antacid use (e.g. long-term PPI therapy with omeprazole) or other conditions causing achlorhydria (e.g. gastritis), will lower the minimum infectious dose of V. cholerae.

NOTE: can be isolated from stool specimens by growing on highly alkaline selective media. It is a comma-shaped, oxidase-positive, gram-negative bacillus

Question 214

What is a noteable substance for having the fastest rate of metabolism in the glycolytic pathway

Answer 214

Non-glucose monosacchardies (e.g. galactose, mannose, fructose) enter the glycolytic pathway at different points as intermediates of glycolysis.

Dietary fructuose is phosphorylated in the liver to F1P and is rapidly metabolized because it bypasses phosphofructokinase (PFK1), the major rate-limiting enzyme of glycolysis. Other sugars (e.g. glucose, galactose, mannose) enter glycolysis prior to PFK1 and as a result are metabolized more slowly.

Question 215

How can the lepromin skin test distinguish the two types of leprosy

Answer 215

The lepromin skin test will be positive in patients with tuberculoid leprosy as they exhibit a strong CD4+ TH1 cell-mediated immune response (IL-2, IFNy, and IL-12) to M. leprae.

Patients with lepromatous leprosy will test negative due to thier weak TH1 cell-medaited immune response. Patients with lepromatous leprosy show extensive accumulation of acid-fast bacilli within macrophages of affected tissues and often a TH2 cytokine profile.

NOTE: In TL, macrophages are activated and kill M leprae organisms, thereby limiting disease extent. However, this localized inflammation damages the skin and cutaneous nerves leading to developmetn of a small number of hypopigmented, well-demarcated plaques with decreased sensation. In comparison, LL is disseminated, with more numerous poorly demarcated plaques, leonine facies and degeneration/loss of nose adn digits.

Question 216

Which medications have known antimuscarinic effects

Answer 216

Atropine, TCA (e.g. amitriptyline), H1 receptor antagonists (e.g. diphenhydramine), neuroleptics, and antiparkinsonian drugs.

Question 217

As a precursor of NO, supplementation with this amino acid may play an adjunct role in treatment of conditions that improve with vasodilation (e.g. stable angina)

Answer 217

Vascular endothelium plays an important role in vasodilation mediated by ACh, bradyinin, serotonin, substance P, and shear force. These stimuli activate specific membrane receptors on endothelial cells, leading to an increase in cytoplasmic calcium levels. This causes activation of endothelial nitric oxide synthase (eNOS), which synthesizes nitric oxide from arginine, NADPH, and O2. Nitric oxxide then diffuses into adjacent smooth muscle cells, where it activates GC and increases cGMP –> activate PKG –> reduction in cytosolic calcium levels and relaxation of vascular smooth muscle cells.

Question 218

What pathology of the heart causes the release of both ANP and BNP from the ventricular myocytes

Answer 218

Both ventricular hypetrophy and volume overload cause release of both ANP and BNP from the ventricular myocyte to facilitate natriuresis and diuresis. BNP can also be used for the diagnosis of CHF (both systolic and diastolic)

Question 219

What disorder occurs in patients with activating mutations involving phosphoribosyl pyrophosphate synthetase

Answer 219

Gout occurs with increased frequency in patients wtih activating mutations involving PPRP synthetase due to increased production and degradation of purines. This enzyme is responsible for the production of activated ribose necessary for de novo synthesis of purine and pyrimidine nucleotides.

Question 220

What is the most common subtype of RCC and how does it present

Answer 220

Clear cell carcinoma is the most common subtype and is composed of large, rounded or polygonal cells with clear cytoplasm; nuclei can be either eccentric or central. Appears clear d/t high glycogen adn lipid content of the tumor; appears golden-yellow on macroscopic exam.

The classic triad of hematuria, flank pain, and palpable mass occurs in a minority of patients. Non-specific symptoms and paraneoplastic syndromes (erythrocytosis and polycythemia d/t secretion of EPO –> elevated hematocrit; PTHrP –> hypercalcemia) are more common. These tumors are often detected incidently at an advanced stage, and the lung is the most common site for mets.

Question 221

What is the msot commonc ause of male hypogonadism

Answer 221

Klinefelter: 47, XXY is characterized by primary hypogonadism (elevated FSH and LH, low testosterone); long lower extremities; small, firm testes; and azoospermia.

Progressive destruction and hyalinization of seminiferous tubles cause testes to be small and firm. Serum inhibin levels are decreased d/t sertolic cell damage; leydig cells are usually dysfunction as well casuing reduced testosterone levels. Loss of feedback inhibition leads to elevated FSH and LH. Can also develop high estrogen levesl and gynecomastia d/t increased aromatase (stimulated by gonadotropin excess)

Question 222

How does hydrocephalus present in infants

Answer 222

Irritability, poor feeding, increased head circumference and enlarged ventricles on CT. Long-term sequelae include lower extremity spasticity due to stretching of the periventricular pyramidal tracts, visual distrubances, and learnign disabilities.

The cause is usually imapired CSF outflow d/t congenital abnormalities like Type II Arnold-Chiari malformations, hereditary aqueductal stenosis, and prenatal infections (e.g. toxo).

Question 223

Describe airway resistance in trachea vs. terminal bronchioles

Answer 223

Although resistance within the trachea and mainstem bronchi is realtively high, it increases in the medium-sized bronchi b/c of highly turbulent airflow. Resistance drops in small bronchi and bronchioles becuase the summated cross-sectional area massively increases. This slows airflow velocity, allowing low-resistance laminar airflow to predominate in airways <2mm in diameter.

Resistance: Medium sized bronchi > Trachea > Bronchioles > Terminal bronchioles

Question 224

What is the MHCH in spherocytosis

Answer 224

Mean corpuscular hemoglobin concentration (MCHC) is increased d/t mild dehydration of the RBC. Markers of hemolysis are often evident and include elevated LDH, reticulocytosis, and decreased haptoglobin. Will show increase osmotic fragility on acidified glycerol lysis test and **abnormal eosin-5-maleimide binding test. **

Question 225

What drug causes QT prolongation but has a low risk of torsades de pointes

Answer 225

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

Question 226

What is lipoic acid a cofactor for

Answer 226

Several mitochondrial enzymes including PDH (decreased function of PDH will increase conversion of pyruvate to lactate by enzyme lactate dehydrogenase in an effort to regenerate NAD+, and this will eventually lead to lactic acidosis), alpha-ketoglutarate DH and branched-chain ketoacid DH (Deficeincy results in maple syrup urine disease)

Question 227

What drugs are used in teh treatment of parkinsons disease

Answer 227

BALSA: Bromocriptine, Amantadine, Levodopa (with carbidopa), Selegiline (and COMT inhibitors), Antimuscarinics.

Dopamine agonits: Bromocriptine and pergolide (ergot compounds) pramipexole and ropinirole (nonergot)

Increase dopamine: Amantadine (may increase DA release); also used as an antiviral against influenza A and rubella; toxicity = ataxia. L-dopa/carbidopa (converted to dopamine in CNS; carbidopopa is a peripheral dopa decarboxylase inhibitior)

Prevent DA breakdown: Selegiline (selective MAO type B inhibitor); entacapone, tolcapone (COMT inhibitors; prevent L-dopa degradation and increase DA availbility; only used in combination with levodopa).

Curb excess cholinergic activitiy: Benzotropine (Antimuscrinic; improves tremor and rigidity but has little effect on bradykinesia).

Question 228

High-oupt CHF and neurological Sx are strongly suggestive of what nutrient deficiency

Answer 228

Suggestive of wet beriberi (thiamine deficeincy).

NOTE: Dry beriberi describes a symmetrical peripheral neruopathy accompanied by sensory and motor impairements, especially of the distal extremtieis. Wet beriberi includes this neruopathy + cardiac involvement.

Question 229

A patient with signs of renal failure and toe gangrene or livedo reticularis followign an invasive vascular procedure likely has what?

Answer 229

Atheroembolic renal disease. LM shows cholesterol emboli obstructing renal arteiroles.

During this procedure, cholesterol-containing debris gets pushed form larger arteries and lodges in smaller vesels, causing ischemia of hte correspondign organs and tissues.

Question 230

Descirbe the manifestation of Drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome

Answer 230

DRESS syndrome typically occurs 2-8 weeks after exposure to high-risk drugs such as anticonvulsants (eg phenytoin, carbamazepine), allopurinol, sulfonamides (eg sulfasalazine), and ABX (eg minocycline, vancomycin). Patients develop fever, generalized LAD, facial edema, diffuse skin rash, eosinophilia, and internal organ dysfucntionn.

Labs: eosinophilia, atypical lymphocytosis, and elevated serum alanine transaminase

Question 231

How can you distinguish b/w benign and malignatn lymph node enlargement

Answer 231

LAD can represent inflammatory changes within teh lymph node (reactive hyperplasia) or malignatn transformation.

Benign lymph node enlargement in response to antigen stimulation is associated with a polyclonal proliferation of lymphocytes. A monoclonal lymphocytic proliferation is strong evidence of malignancy. When examining the rearrangemetn of TCR genes, if a single allele for the V region of the TCR predominatnes in a lymphcotyic population than monoclonal proliferation is suspected.

Question 232

What leads to the developmetn of propionic acidemia (see 1340)

Answer 232

Propionyl CoA is derived from branched chain AAs (valine, isoleucine), methionine, threonine, odd-numbered FAs, and cholesterol side chains. Congential deficieincy of propionyl CoA carboxylase, the enzyme responsible for conversion of propionyl CoA to methylmalonyl CoA, leads to developmetn of propionic acidemia.

Propionic acidemia is characterized by poor feeding, vomitting, hypotonia, lethary, dehydration and anion gap acidosis.

Question 233

What is the best way to prevent neonatal tetanus

Answer 233

To ensure that all pregnant women have been vacinated with the tetanus toxoid, to allow transfer of protective IgG antitoxin antibodies across the placenta to the fetus.