Uworld18

Question 1

Urge incontinence can be treated with neuromodulation directed toward which nerve roots?

Answer 1

Directed toward the S2-4 nerve roots, which improves pelvic floor muscle strength and contraction of the external urethral sphincter; it may also impact the bladder stretch contraction reflex

Question 2

By age 3, a child is expected to?

Answer 2

ride a tricycle, play with others, and speak in simple sentences.

Fine motor milestones for this age include ability to copy a circle, help dress oneself, and use utensils

Question 3

What is thrombotic thrombocytopenia purpura?

Answer 3

classically presents with the pentad of severe thrombocytopenia, microangiopathic hemolytic anemia (eg, schistocytes on peripheral smear), renal insufficiency, neurologic symptoms, and fever. however, all these signs and symptoms are rarely present.

Diagnosis is often made by identifying severe deficiency of ADAMTS-13, a protease that cleaves large von Willebrand factor multimers off the endothelium

Question 4

Function of vitamin K

Answer 4

Vit K is necessary for carboxylation of coagulation factors II, VII, IX, and X.

Newborns who do not receive prophylactic supplementation are at risk for life threatening bleeding (eg, intracranial hemorrhage)

Patient with cystic fibrosis are also at increased risk for vitamin K def due to malabsorption of fat soluble vitamins

Question 5

How does candida albicans look under the microscope?

Answer 5

Microscopic examination of Candida albicans, a common invasive infection in patients with neutropenia, reveals budding yeasts and pseudohyphae. It can be differentiated from other Candida species by a positive germ tube test.

Question 6

What is an atrial septal defect?

Answer 6

Atrial septal defects cause wide, fixed splitting of S2 due to right-sided volume overload from left to right shunting.

Uncorrected defects can lead to irreversible medial hypertrophy of the pulmonary arteries with pulmonary hypertension and reversal to right to left shunting (ie, Eisenmenger syndrome)

Question 7

Treatment with statins causes hepatocytes to?

Answer 7

increase their LDL receptor density, leading to increased uptake of circulating LDL

Question 8

Excess unconjugated bilirubin in the neonatal period, often caused by increased hemolysis, can cross the blood brain barrier and deposit in?

Answer 8

the basal ganglia and brainstem nuclei. If inadequately treated, this can lead to chronic, irreversible neurologic dysfunction, including abnormal movements (eg, chorea, dystonia) and impaired vision and hearing.

Question 9

What is seen on neuroimaging for Huntington disease?

Answer 9

Huntington disease is an AD neurodegenerative disorder that manifests with chorea (involuntary, jerky, fidgety movements) and behavioral abnormalities (aggressiveness, depression).

Neuroimaging: atrophy of the caudate nuclei which results in enlargement of the frontal horns of the lateral ventricles

Question 10

Cardiovascular dysphagia can result from external compression of the esophagus by?

Answer 10

a dilated and posteriorly displaced left atrium in patients with rheumatic heart disease and mitral stenosis/regurg

Question 11

Formation of uric acid kidney stones is promoted by?

Answer 11

low urine pH, which favors formation of insoluble uric acid over soluble urate ion.

Gastrointestinal bicarbonate loss due to chronic diarrhea leads to chronic metabolic acidosis and production of acidic urine, promoting formation of uric acid stones

Question 12

What is myotonic dystrophy type 1?

Answer 12

due to a cytosine-thymine-guanine trinucleotide repeat expansion in the dystrophia myotonica protein kinase (DMPK) gene, resulting in untranslateable mutant mRNAs.

The mutant mRNAs form hairpin structures and accumulate in the nucleus, sequestering certain RNA binding proteins and leading to aberrant splicing.

Nondividing cells of the brain, skeletal muscles, and myocardium are particularly affected.

Question 13

Why does ACE inhibitors cause angioedema?

Answer 13

Angioedema is a rare and serious AE of ACE inhibitor therapy.

ACE inhibition increases bradykinin levels, which increase vascular permeability and lead to angioedema.

Symptoms include tongue, lips, or eyelid swelling and less frequently laryngeal edema and difficulty breathing. ACE inhibitors should be discontinued in affected patients.

Question 14

Traits of campylobacter jejuni?

Answer 14

oxidase positive, G-, curved rod that is a leading cause of gastroenteritis.

A zoonotic organism most commonly contracted by consuming contaminated, undercooked poultry. The infection is marked by fever, abdominal pain, and diarrhea that may be bloody

Question 15

Function of duodenal S-cells?

Answer 15

Duodenal S-cells secrete secretin in response to increasing H+ concentrations.

Secretin increases pancreatic bicarbonate secretion.

The chloride content of pancreatic secretions decreases in proportion to bicarbonate concentration increases.

Question 16

Fibrate meds (fenofibrate, gemfibrozil) inhibit?

Answer 16

cholesterol 7a-hydroxylase, which catalyzes the rate limiting step in the synthesis of bile acids.

The reduced bile acid production results in decreased cholesterol solubility in bile and favors the formation of cholesterol gallstones

Question 17

What is the first step in the classic adenoma to carcinoma sequence?

Answer 17

Mutation of the APC tumor suppressor gene; it is found in most cases of sporadic colon cancer and in all patients with familial adenomatous polyposis.

The microsatellite instability pathway is characterized by mutations in DNA mismatch repair genes and is implicated in the development of hereditary nonpolyposis colorectal cancer (Lynch syndrome)

Question 18

What is Meniere disease?

Answer 18

episodic vertigo, sensorineural hearing loss, and tinnitus with aural fullness.

Its pathogenesis is related to an increased volume and pressure of endolymph in the vestibular apparatus

Question 19

How to calculate risk?

Answer 19

Risk is the probability of developing a disease over a certain period of time.

Divide the number of affected subjects by the total number of subjects in the corresponding exposure group

Question 20

What is a cross-sectional study?

Answer 20

In a cross sectional study, exposure and outcome are measured simultaneously at a particular point in time (“snapshot study”). In other study designs, a certain time period separates the exposure from the outcome

Question 21

Diastolic blood pressure is largely determined by?

Answer 21

systemic vascular resistanceP

Question 22

pulse pressure is largely determined by?

Answer 22

stroke volume

Question 23

What occurs during aerobic exercise on blood pressure?

Answer 23

During aerobic exercise, reduced SVR leads to slightly decreased or unchanged DBP, and increased stroke volume leads to increased pulse pressure and systolic blood pressure

Question 24

What is seen in a positive Trendelenburg sign?

Answer 24

Superior gluteal nerve injury results in weakness and paralysis of the gluteus medius, gluteus minimus, and tensor fasciae latae muscles.

This causes the pelvis to tilt downward toward the contralateral side (positive Trendelenburg sign).

Patients will also lean toward the ipsilateral side when walking to help stabilize the pelvis (gluteus medius gait)

Question 25

Formula for half life

Answer 25

half life is a measure of how quickly a drug with first order kinetics is eliminated from the body. A drug is almost completely eliminated after 5 half life intervals. The half life can be calculated from the drug's volume of distribution (Vd) and clearance rate (CL): t1/2= (0.7 x Vd)/CL

Question 26

What can predispose patients to Giardia?

Answer 26

Giardia lamblia causes injury to the duodenal and jejunal mucosa by adhering to the intestinal brush border and releasing molecules that induce a mucosal inflammatory response. Secretory IgA, which impairs adherence, is the major component of adaptive immunity against G lamblia infection. Conditions causing IgA def predispose patients to chronic giardiasis

Question 27

What is the acid base for advanced chronic kidney disease?

Answer 27

Advanced chronic kidney disease typically involves the accumulation of unmeasured acidic compounds in the blood; therefore, anion gap metabolic acidosis with resp compensation is expected.

Question 28

What is drug induced lupus?

Answer 28

abrupt onset lupus symptoms (fever, arthralgia, pleuritis) with positive antihistone antibodies. It has been linked to drugs metabolized by N-acetylation in the liver (eg, procainamide, hydralazine, isoniazid). Genetically predisposed indivudals with slow acetylator phenotype are at greater risk for DILE.

Question 29

Postoperative hypoparathyroidism with resultant hypocalcemia is a common complication of thyroidectomy due to inadvertent injury or removal of the parathyroid glands. What can be given postoperative supplementation?

Answer 29

oral calcium and vitamin D (calcitriol)

Question 30

What is preeclampsia?

Answer 30

new onset hypertension at >20 weeks gestation plus proteinuria and/or signs of end organ damage. Caused by widespread maternal endothelial cell damage due to release of antiangiogenic factors from an ischemic placenta. The result is widespread capillary leakage (proteinuria, edema) and vasospasm (hypertension, end organ hypoperfusion (eg renal failure)

Question 31

MOA of nitrates

Answer 31

Nitrates are primarily venodilators and increase peripheral venous capacitance, thereby reducing cardiac preload and left ventricular end-diastolic volume and pressure. At high doses, nitrates also cause some degree of arteriolar dilation with a resulting decrease in systemic vascular resistance

Question 32

What cells cannot utilize ketones for energy?

Answer 32

When glycogen stores are depleted during fasting, ketone bodies are produced in the liver and can be used as an energy source in the mitochondria of peripheral tissues. The brain prefers glucose, but will use ketones for most of its energy needs during prolonged starvation. Erythrocytes lack mitochondria and are unable to use ketones.

Question 33

What can be given to protect from nuclear accidents involving iodine 131?

Answer 33

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

Question 34

What is a complication of thiamine deficiency?

Answer 34

Thiamine is a cofactor for several enzymes involved in glucose metabolism. A complication of thiamine def is Wernicke encephalopathy (encephalopathy, ataxia, oculomotor dysfunction), which can be precipitated by a high glucose load causing rapid depletion of limited thiamine stores.

Question 35

What causes walking pneumonia?

Answer 35

Mycoplasma pneumoniae is the causative agent of walking pneumonia, an infection typically characterized by a nagging nonproductive cough, low grade fever, and malaise. Often, the chest xray suggests a severe pneumonia even though the patient appears relatively well. Mycoplasma species require cholesterol supplementation to grow on artificial media.

Question 36

Function of prostacyclin (prostaglandin I2)

Answer 36

It is synthesized from prostaglandin H2 by prostaclycin synthase in vascular endothelial cells. Once secreted, it inhibits platelet aggregation and causes vasodilation to oppose the functions of thromboxane A2 and help maintain vascular homeostasis.

Question 37

what is systemic sclerosis? histo?

Answer 37

Systemic sclerosis is an autoimmune characterized by the widespread fibrosis of multiple organ systems. Histo: expansion of the dermal layer with diffuse collagen deposition and atrophy of the intradermal adipose tissue and dermal appendages. Pulmonary complications are common (eg, interstitial lung disease, pulmonary hypertension)

Question 38

Location sites of splicing

Answer 38

Splicing is performed by spliceosomes, which remove introns containing GU at the 5' splice site and AG at the 3' splice site. Splice site mutations may result in inappropriate removal of exons and retention of introns, leading to the formation of dysfunctional proteins.

Question 39

What is a choriocarcinoma?

Answer 39

a malignant form of gestational trophoblastic disease composed of anaplastic cytotrophoblasts and syncytiotrophoblasts without villi. It often presents as dyspnea/hemoptysis due to pulmonary metastasis from hematogenous spread.

Question 40

What is the role of osteoprotegerin?

Answer 40

The receptor activator of nuclear fator kappa B (RANK/RANK ligand) interaction is essential for the formation and differentiation of osteoclasts. Osteoprotegerin blocks binding of RANK-L to RANK and reduces formation of mature osteoclasts. Low estrogen states cause osteoporosis by decreasing osteoprotegerin production, increasing RANK-L production, and increasing RANK expression in osteoclast precursors.

Question 41

What is the analysis of variance test?

Answer 41

compares the means of >3 groups. The test requires a categorical independent variable (ie, exposure) that is used to divide the study pool into >3 groups and a quantitative dependent variable (ie, outcome) for which an average (eg, mean) can be calculated.

Question 42

What artery is occluded in lateral medullary (wallenberg) syndrome?

Answer 42

Posterior inferior cerebellar artery. This disorder is characterized by vertigo/nystagmus, ipsilateral cerebellar signs, loss of pain/temp sensation in the ipsilateral face and contralateral body, bulbar weakness, and ipsilateral Horner syndrome

Question 43

Acute hepatitis is due to?

Answer 43

due to most hepatotropic viruses causes hepatocyte injury (eg, ballooning degeneration) and cell death with mononuclear cell infiltration

Question 44

Overuse of topical preparatiosn of a-adrenergic agonists can cause?

Answer 44

cause vasoconstriction of the nasal mucosa vessels and are used as decongestants. Overuse of these drugs causes negative feedback, resulting in decreased norepinephrine synthesis and release from nerve endings, which diminishes their effect (ie, tachyphylaxis)

Question 45

Most common lab abnormality in Legionella pneumonia?

Answer 45

hyponatremia. Legionella pneumophila is a facultative intracellular gram negative bacillus that can cause a systemic infection. symptoms: high fever, cough, confusion, and diarrhea. Gram stain shows many neutrophils but few or no organisms

Question 46

What immunoglobulin response does a vaccination generate?

Answer 46

Initial vaccination generates an early IgM response by short-lived plasma cells followed by a delayed onset, longer lasting IgG response due to T cell dependent class switching (IgM peaks before IgG). Due to formation of memory B cells, secondary responses (eg, booster vaccination, pathogen exposure) are characterized by a rapid and sustained IgG response with a short-term, more muted IgM response

Question 47

What is Duchenne muscular dystrophy?

Answer 47

an X-linked recessive myopathy that manifests with proximal muscle weakness and enlargement of the calf muscles in boys age 2-5. It most often results from frameshift deletions affecting the dystrophin gene. Dystrophin provides a stabilizing interaction between the sarcolemma and the intracellular contraction apparatus, and disruption of the protein results in membrane damage and myonecrosis

Question 48

Difference in pulsatile and constant infusion of GnRH?

Answer 48

Pulsatile administration of gonadotropin-releasing hormone stimulates FSH and LH release and is useful for the treatment of infertility. Nonpulsatile (constant) infusion of GnRH, or a long acting analog, suppresses FSH and LH release and subsequently suppresses gonadal function.

Question 49

What is congenital long QT syndrome?

Answer 49

commonly caused by a mutation that slows the delated rectifier potassium current that repolarizes the cardiomyocyte action potential. Certain meds (eg, macrolide antibiotics, antipsychotics, antiemetics) also slow the potassium repolarization current and prolong the QT interval. Excessive QT prolongation can trigger serious cardiac arrhythmia (ie, torsades de pointes), resulting in syncope or sudden cardiac death

Question 50

What can cause ovarian torsion?

Answer 50

Ovarian torsion typically involves twisting of the infundibulopelvic ligament, often due to the weight of a large adnexal mass. The resulting occlusion of the blood supply to the ovary results in severe, acute pelvic pain and ovarian ischemia

Question 51

What is a galactorrhea? Treatment?

Answer 51

abnormal secretion of breast milk not associated with pregnancy or breastfeeding. It is most commonly due to excess prolactin, as seen in prolactin-secreting pituitary adenomas. Prolactin is under negative regulation by hypothalamic dopaminergic neurons, and dopamine agonists can be used to treat hyperprolactinemia

Question 52

What is frontotemporal dementia?

Answer 52

Presents with early personality change, executive dysfunction, compulsivity, and hyperorality. Neuropathologic findings include neurofibrillary tangles due to abnormal tau proteins (also seen in Alzheimer dementia) and pathologically ubiquitinated TDP-43 (also seen in amyotrophic lateral sclerosis)

Question 53

Amyotrophic lateral sclerosis causes both upper and lower motor neuron degenerative lesions. What is seen?

Answer 53

Loss of upper motor neurons leads to atrophy of the precentral motor gyrus and degeneration of the corticospinal tracts. Loss of lower motor neurons leads to thinning of the anterior roots of the spinal cord and atrophy of cranial nerve motor nuclei

Question 54

Patients with polycystic ovary syndrome can have an increased risk for?

Answer 54

Polycystic ovary syndrome present with irregular menses, hyperandrogenism (eg, acne, hirsutism), and anovulatory infertility. Patients are at increased risk for endometrial hyperplasia and carcinoma due to increased estrogen production and chronic anovulation

Question 55

Reticulocytes (immature red blood cells) appear as blue-gray (ie, polychromatophilic) red blood cells on Wright-Giemsa staining due to?

Answer 55

the presence of ribosomal RNA. In patients with iron deficiency anemia, iron supplementation results in increased bone marrow erythropoiesis and accelerated release of reticulocytes into the bloodstream.

Question 56

What is scleroderma renal crisis?

Answer 56

a life threatening complication of systemic sclerosis characterized by acute renal failure and severe hypertension. SRC is caused by immune-mediated injury to small renal vessels that leads to reduced renal perfusion due to vascular narrowing and obliteration

Question 57

What is temporomandibular joint disorder?

Answer 57

associated with dysfunction of the temporomandibular joint and hypersensitivity of the mandibular nerve (CNV3). This can result in pathologic contraction of the muscles of mastication, including the masseter and pterygoids.

Question 58

Patients with decompensated heart failure have elevated left ventricular end-diastolic pressure and decreased cardiac output that is most often primarily due to?

Answer 58

left ventricular dysfunction. Right atrial pressure (ie, central venous pressure) is also elevated in advanced heart failure due to volume overload; right sided heart failure (most often occuring secondary to left sided failure) can also contribute to elevated right atrial pressure.

Question 59

The pathogenesis of centriacinar emphysema associated with chronic, heavy smoking predominantly involves?

Answer 59

the release of proteases, especially elastase, from infiltrating neutrophils and alveolar macrophages

Question 60

What is ornithine transcarbamylase deficiency?

Answer 60

Patients with urea cycle disorders typically have discrete episodes of vomiting, tachypnea, and confusion/coma secondary to hyperammonemia (a metabolic emergency). Ornithine transcarbamylase deficiency is the most common disorder of that urea cycle and is characterized by hyperammonemia and elevated urinary orotic acid

Question 61

What is the major virulence factor for Haemophilus influenzae type b (Hib)?

Answer 61

Polyribosylribitol phosphate is a capsule component and major virulence factor for Haemophilus influenzae type b (Hib). Hib is the most common cause of epiglottitis, which presents with fever, stridor, and dyspnea

Question 62

Transmission of hep A occurs through?

Answer 62

fecal-oral route and is common in areas with overcrowding and poor sanitation. Outbreaks frequently result from contaminated water or food, and raw or steamed shellfish is a common culprit in the US.

Question 63

Focal onset seizures most commonly occur due to?

Answer 63

a focal structural abnormality (eg, stroke, neoplasm) that causes a region of hyperexcitable neuronal activity in one cerebral hemisphere. These seizures begin with localized symptomatology (eg, muscle twitching, paresthesia) and are classified according to level of consciousness (eg, aware, impaired awareness). They can progress to bilateral tonic-clonic seizures if the excitatory neuronal activity spreads to involve both cerebral hemispheres

Question 64

Heparin induced thrombocytopenia is treated with?

Answer 64

direct thrombin inhibitors such as argatroban (binds to thrombin active site) Both high molecular weight heparin and LMWH should be avoided in these patients.

Question 65

What are common autopsy findings for anaphylaxis?

Answer 65

Anaphylaxis (Type 1 HSR) can quickly lead to respiratory compromise (eg, bronchospasm, oropharyngeal edema) and distributive shock. The most common autopsy findings include upper airway edema, hyperinflation of the lungs from airway obstruction, and cerebral edema from hypoxia

Question 66

What is specificity?

Answer 66

The specificity of a test is its ability to correctly identify individuals without the disease. Specificity should be high in confirmatory tests to decrease false positives. Spec = TN/ (TN+FP)

Question 67

What is Gilbert syndrome?

Answer 67

a benign disorder that presents with recurrent scleral icterus and jaundice, typically triggered by stress (eg, fasting, illness) Pathogenesis involves decreased activity of UDP glucuronosyltransferase (impaired bilirubin conjugation), and an isolated mild unconjugated hyperbilirubinemia is typical

Question 68

What is seen on synovial fluid analysis for pseudogout?

Answer 68

Synovial fluid analysis showing rhomboid-shaped calcium pyrophosphate dehydrate crystals is diagnostic of pseudogout. These crystals are positively birefringent under compensated polarized light. The knee joint is involved in >50% of cases

Question 69

MOA of methotrexate

Answer 69

Methotrexate is a folic acid antagonist used to treat ectopic pregnancy. It competitively inhibits the enzyme dihydrofolate (DHF) reductase, which catalyzes the synthesis of tetrahydrofolate. DHF reductase inhibition causes the intermediate DHF to accumulate intracellularly

Question 70

Urge incontinence (overactive bladder syndrome) is caused by?

Answer 70

uninhibited bladder contractions (detrusor instability). It results in a sense of urgency accompanied by an involuntary loss of urine. If behavioral therapy alone is unsuccessful, pharmacologic therapy with an antimuscarinic drug (targeting M3 receptors) can help improve symptoms

Question 71

What results in an abnormal connection between the bladder and the umbilicus?

Answer 71

Congenital anomalies of the urachus result in an abnormal connection between the bladder and the umbilicus. Full patency results in urinary umbilical leakage, whereas partial patency can result in a range of defects, including a bladder diverticulum (increases the risk of urinary tract infection due to stasis of urine)

Question 72

MOA of class IV antiarrhythmics (verapamil, diltiazem)

Answer 72

commonly used to prevent recurrent nodal arrhythmias (eg, paroxysmal supra ventricular tachycardia) They work by blocking calcium channels in slow response cardiac tissues, slowing phase 4 (spontaneous depolarization) and phase 0 (upstroke). This reduces impulse conduction velocity in the sinoatrial and atrioventricular nodes

Question 73

What is seen on CSF for herpes encephaliti?

Answer 73

Viral infections of the central nervous system are usually characterized by an elevated WBC count with a lymphocytic predominance, normal glucose, and elevated (or normal) protein. Patients with herpes encephalitis also usually have elevated erythrocytes in the CSF due to hemorrhagic inflammation of the temporal lobes. Presents with acute fever, headache, confusion, focal neurologic deficits, and/or seizure

Question 74

What is supraventricular tachycardia?

Answer 74

elevated heart rate with a regular rhythm and narrow QRS complexes due to an abnormal electrical impulse originating above the ventricles. Sustained tachycardia shortens ventricular diastole, leading to decreased stroke volume and cardiac output and subsequent hypotension

Question 75

What can be used to treat the motor symptoms of Parkinson disease?

Answer 75

Dopamine agonists have a chemical structure similar to that of the neurotransmitter dopamine and directly stimulate dopamine receptors. They can be used instead of, or in addition to, levodopa therapy to treat the motor symptoms of Parkinson disease (eg, bradykinesia, rigidity, tremor)

Question 76

Function of interferons alpha and beta

Answer 76

Interferons alpha and beta are produced by most human cells in response to viral infections. The production of the alpha and beta interferons helps suppress viral replication by halting protein synthesis and promoting apoptosis of infected cells, limiting the ability of viruses to spread through the tissues

Question 77

Methicillin-resistant staph aureus is resistant to?

Answer 77

all beta-lactam antibiotics, including beta lactamase resistant antibiotics, as it has an altered penicillin-binding protein that does not bind beta lactams effectively

Question 78

What is odds ratio?

Answer 78

measure of the strength of an association between an exposure and an outcome. Specifically, it represents the odds that an outcome occurred in the presence of a particular exposure compared with the odds that the outcome occured in the absence of that exposure OR= ad/bc

Question 79

What is typhoid fever?

Answer 79

caused by Salmonella typhi or paratyphi and presents with escalating fever, followed by abdominal pain, formation of rose spots on the chest/abdomen, and hemorrhagic enteritis with possible bowel perforation. Humans are the only reservoir; transmission is fecal-oral and primarily occurs due to ingestion of food or water contaminated with feces

Question 80

MOA and AE for sodium-glucose cotransporter-2 inhibitors (canagliflozin, dapagliflozin)

Answer 80

decrease renal reabsorption of glucose, leading to urinary glucose loss and decreased blood glucose levels However, the resultant glycosuria can lead to genitourinary tract infections and genital mycotic infections

Question 81

Locations of steroidogensis

Answer 81

The initial step in the synthesis of steroid hormones is the conversion of cholesterol to pregnenolone in the mitochondria. The remainder of steroidogenesis occurs in the smooth endoplasmic reticulum. Steroid-producing cells contain a well developed smooth endoplasmic reticulum

Question 82

What is an early change that occurs in the renal tubular cells in response to ischemia (ie, acute tubular necrosis)?

Answer 82

loss of epithelial cell polarity; depletion of ATP causes rapid cytoskeletal disruption; this leads to a loss of cell-cell adhesion and causes redistribution of integrins and Na-K-ATPases from the basolateral membrane to the apical membrane

Question 83

What is the most common cause of croup?

Answer 83

Parainfluenza virus; brassy, barking cough, dyspnea, and recent history of upper respiratory infection in a child are suggestive of viral laryngotracheitis (croup)

Question 84

How is Entamoeba histolytic infection treated?

Answer 84

Symptomatic Entamoeba histolytica infection must be treated with a tissue agent followed by an intraluminal agent. Tissue agents (eg metronidazole) kill trophozoites responsible for symtomatic disease, and intramluminal agents (eg, paramomycin) eradicate intestinal cyst carriage

Question 85

What is a ganglion cyst?

Answer 85

benign, fluid filled masses that occur due to mucoid degeneration of periarticular tissue. They present as painless, smooth, rubbery, round structures that overlie joints (eg, wrists) or tendons and transilluminate with a penlight. Most resolve spontaneously without intervention

Question 86

Mutations in homeobox genes lead to?

Answer 86

Mutations in homeobox genes lead to congenital malformations involving positioning and patterning (eg, synpolydactyly in HOXD13 mutation). Homeobox genes code for transcription factors that bind regulatory regions on target genes involved in the segmental organization of the embryo along the craniocaudal body axis.

Question 87

Visual loss in only one eye indicates?

Answer 87

that the lesion is anterior to optic chiasm. Images projected onto the retina are inverted and reversed.

Question 88

What is Lambert-Eaton myasthenic syndrome?

Answer 88

neuromuscular disorder characterized by autoantibodies against presynaptic voltage gated calcium channels. It causes progressive proximal muscle weakness and decreased deep tendon reflexes that improve with exercise (postexercise facilitation); cranial nerve involvement and autonomic symptoms may also occurs. LEMS is strongly associated with small cell lung cancer.

Question 89

What can cause an injury to the common fibular (peroneal) nerve?

Answer 89

The common fibular nerve is vulnerable to injury where it courses around the neck of the fibular. It can be injured when the gfibular neck is fractured, resulting in loss of sensation over the dorsum of the foot, as well as weakness of foot dorsiflexion (deep fibular nerve) and eversion (superficial fibular nerve)

Question 90

Hypovolemia due to a loss of sodium and/or water causes?

Answer 90

increased concentrations of red blood cells (ie, hematocrit) and albumin as both of these blood components are trapped within the intravascular space. Hypovolemia also triggers increased absorption of uric acid in the proximal renal tubule, resulting in an increased serum uric acid level.

Question 91

How does infection with Histoplasma capsulatum present?

Answer 91

Histopalsma capsulatum replicates within macrophages and often spreads from the lungs through the pulmonary lymphatics to the reticuloendothelial system (eg, spleen, liver) Most healthy individuals quickly contain the infection within granulomas and do not become ill; a minority develop self limited pneumonia. Over time, the granulomas at the initial sites of infection calcify and may be seen incidentally on radiographic imaging.

Question 92

What is the relationship of vitamin D and sarcoidosis?

Answer 92

Excessive vitamin D intake can lead to hypercalcemia and cause mental status changes, muscle weakness, constipation, and polyuria/polydipsia. Activated macrophages in sarcoidosis and other granulomatous diseases express 1-alpha-hydroxylase, leading to excess production of 1,25-dihydroxyvitamin D and hypercalcemia

Question 93

When does the aortic valve open?

Answer 93

when the left ventricular pressure exceeds the central aortic pressure at the end of isovolumetric contraction

Question 94

What is a health maintenance organization?

Answer 94

insurance plan with low monthly premiums, low copayments and deductibles, and low total cost for the patient. HMOs reduce utilization by confining patients to a limited panel of providers, requiring referral from a primary care provider prior to specialist consultations, and denying payment for services that do not meet the established guidelines

Question 95

What can northern blots be used for?

Answer 95

Northern blots detect target mRNA in a sample and can be used to assess the degree of gene transcription

Question 96

MOA of niacin

Answer 96

Niacin is used in the treatment of hyperlipidemia It increases HDL levels and decreased LDL levels and triglycerides. Niacin causes cutaneous flushing, which is mediated by prostaglandins and can be diminished by pretreatment with aspirin

Question 97

What is aplastic anemia?

Answer 97

a form of bone marrow failure in which patients have decreased production of all cell lines (platelets, erythrocytes, and leukocytes). It is primarily caused by the autoimmune destruction of multipotent hematologic stem cells due to an alteration in their surface antigens, leading to a cytotoxic T cell response and release of interferon-gamma from T helper cells (triggers apoptotic cell death)

Question 98

Formula for sensitivity

Answer 98

sensitivity = true positives / (true positives + false negatives) Screening tests should have high sensitivity

Question 99

What causes the green color to develop in bruises?

Answer 99

Heme oxygenase converts heme to biliverdin, a pigment that causes the greenish color to develop in bruises several days after an injury.

Question 100

T lymphoblastic leukemia (T-ALL) is characterized by?

Answer 100

circulating lymphoblasts that express terminal deoxynucleptidyl transferase (TdT) and CD3. T-ALL often presents in adolescents/young adults with a mediastinal mass