Uworld22 Flashcards

Question

The optimal site for obtaining vascular access in the lower extremity during cardiac catheterization is?

Answer 1

the common femoral artery below the inguinal ligament. Cannulation above the inguinal ligament can significantly increase the risk of retroperitoneal hemorrhage.

Answer 2

decrease renal reabsorption of glucose and sodium, leading to increased urinary glucose excretion and decreased blood glucose levels. In addition, natriuresis and osmotic diuresis lead to a small decrease in extracellular fluid volume, total body sodium content, and blood pressure.

Answer 3

Spironolactone is an aldosterone antagonist commonly used to treat heart failure. It has significant antiandrogenic effects and can cause gynecomastia, decreased libido, and impotence. Eplerenone is a more selective aldosterone antagonist with fewer adverse effects

Answer 4

Aortic dissection classically presents with severe retrosternal pain that radiates to the back. This condition develops when overwhelming hemodyanmic stress leads to tearing of the aortic intima with blood subsequently dissecting through the aortic media. The resulting intramural hematoma can extend both proximally and distally and can compress major arterial branches and impair blood flow.

Answer 5

most commonly seen in elderly men and involves an exaggerated vasovagal response to tactile stimulation of carotid sinus baroreceptors (eg, adjusting a shirt collar or necktie). The resulting increase in parasympathetic output leads to a prolonged sinus pause that contributes to the excessive drop in blood pressure, leading to transient loss of cerebral perfusion that manifests as presyncope (eg, lightheadedness) or syncope

Answer 6

primarily use oxidative phosphorylation and contain high quantities of lipids, myoglobin, and mitochondria. They are specialized in sustained, low force contraction, and their function is amplified by endurance training.

Answer 7

primarily use glycolysis and specialize in rapid bursts of high force contraction. Their function is amplified by resistance training.

Answer 8

a clonal myeloproliferative disease characterized by an increased RBC mass and low erythropoietin levels. The majority of patients with PV have a JAK2 mutation causing hematopoietic stem cells to proliferate uncontrollably.

Answer 9

by the presence of leukocytosis, thrombocytosis, and/or splenomegaly.

Answer 10

Shigella is a non-lactose fermenting organism that does not produce hydrogen sulfide on triple sugar iron agar. Mucosal invasion is the primary pathogenic mechanism for Shigella infection, which presents with bloody/mucoid diarrhea.

Answer 11

Chronic hypertension can result in hypertensive nephrosclerosis, which is characterized by compensatory medial hypertrophy and fibrointimal proliferation; endothelial damage from elevated systemic pressure also leads to hyaline arteriolosclerosis. The narrowed arteriolar lumens cause a progressive decrease in renal blood flow, resulting in glomerular ischemia and fibrosis (glomerulosclerosis)

Answer 12

Alpha-1 blockers such as doxazosin, prazosin, and terazosin are useful for the treatment of both benign prostatic hyperplasia and hypertension. To minimize adverse effects and drug interactions, it is desirable to prescribe a medication that can address multiple issues at once.

Answer 13

hepatic P450 oxidases and is dose dependent. Drugs that induce hepatic microsomal enzymes (phenobarbital, carbamazepine, and rifampin) enhance phenytoin metabolism and decrease its serum concentraion.

Answer 14

primarily due to a polysaccharide capsule. A conjugate vaccine provides long lasting immunity against serotypes in the vaccine but provides no significant immunity against nonvaccinated serotypes. Therefore, infection can still occur due to serotypes not covered by the vaccine.

Answer 15

Kaposi sarcoma often presents as multiple red, purple, or brown lesions on the lower extremities in patients with HIV infection. It is a vascular tumor caused by human herpesvirus type 8 infection of endothelial cells.

Answer 16

new onset hypertension (systolic >140 or diastolic >90) with proteinuria and/or signs of end organ damage (eg, renal insufficiency). Preeclampsia is associated with widespread maternal endothelial dysfunction, which occurs due to increased antiangiogenic factor release and decreased proangiogenic factor activity (eg, vascular endothelial growth factor)

Answer 17

inhibit the L-type calcum channel on vascular smooth muscle and cardiac cells. Dihydropyridines (eg, nifedipine, amlodipine) primarily affect peripheral arteries and cause vasodilation. Nondihydropyridines (eg, verapamil, diltiazem) affect the myocardium and can cause bradycardia and slowed atrioventricular conduction.

Answer 18

typically occurs in patients with massive small bowel resection and/or Crohn disease due to loss of intestinal absorptive surface area and a decrease in intestinal transit time. Patients usually present with postpranial voluminous diarrhea and weight loss due to malabsorption. Loss of functional distal ileum may result in vitamin B12 def.

Answer 19

Papillary thyroid carcinoma. Characteristic microscopic features include large cells with nuclei containing finely dispersed chromatin, giving them an empty or ground glass appearance (ie, Orphan Annie eyes), and intranuclear inclusions and nuclear grooves

Answer 20

The coronary sinus communicates freely with the right atrium and will become dilated secondary to any factor that causes increased right atrial pressure. The most common cause is pulmonary hypertension, leading to elevated right heart pressures

Answer 21

often present with rapid-onset, severe, unilateral pain accompanied by ipsilateral autonomic symptoms (eg, ptosis, miosis, nasal congestion, conjunctival injection.

Answer 22

splenic dysfunction, which occurs in sickle cell disease due to recurrent infarction of the splenic vasculature. Functional asplenia increases the risk of invasive infection with encapsalted organisms.

Answer 23

adequate platelet hemostatic function.

Answer 24

an intact intrinscic coagulation system.

Answer 25

a defect in the extrinsic coagulation system at a step that is not shared with the intrinsic system

Answer 26

TAP proteins are necessary for loading of cytoplasmic (eg, viral) proteins onto major histocompatibility complex (MCH) class I molecules. The MHC class I peptide complex can then activate CD8 cytotoxic T cells through interaction with the T cell receptor and CD8 coreceptor

Answer 27

5alpha-reductase converts testosterone to dihydrotestosterone, which mediates development of the external genitalia in the male fetus. Male neonates with 5alpha-reductase def are born with ambiguous genitalia that typically masculinize at puberty

Answer 28

DNA replication occurs in the 5'-3' direction on both strands. In contrast to the continous systhesis of the leading strand, lagging strand synthesis occurs discontinuously and is composed of short stretches of RNA primer plus newly synthesized DNA segments (Okazaki fragments). As a result, lagging strand synthesis requires the repetitive action of DNA primase and DNA ligase

Answer 29

associated with a grayish-white, malodorous vaginal discharge due to an overgrowth of Gardnerella vaginalis, a facultative anaerobic, gram variable rod. Clue cells (squamous epithelial cells are covered with bacterial organisms) are seen on wet mount.

Answer 30

caused by filaggrin gene mutations that result in defective keratinocyte desquamation. It is characterized by dry, scaly skin; manifestations are diffuse but are typically worse on the trunk and the extensor surfaces of the extremities.

Answer 31

hypertensive vasculopathy involving the small, penetrating branches of the major cerebral arteries. The most frequently affected locations include the basal ganglial (putamen), cerebellar nuclei, thalamus, and pons. The putamen is supplied by the lenticulostriate arteries, which are deep, small vessel branches off the middle cerebral arteries.

Answer 32

by blocking D2 receptors on lactotrophs. Elevated prolactin leads to amenorrhea (inhibition of gonadotropin-releasing hormone release), galactorrhea, and breast soreness. The secretion of prolactin is controlled by the inhibitory effect of hypothalamic dopamine.

Answer 33

diphteria antitoxin (passive immunization), which inactivates circulating toxin. Antibiotics should also be administered to reduce continued production of toxin.

Answer 34

Age-related sleep changes may be reported as insomnia and must be differentiated from primary sleep disorders and other disorders. Normal changes include decreased total sleep time, increased nighttime awakenings, sleepiness earlier in the evening with earlier morning awakening, and increased daytime napping.

Answer 35

commonly occurs in alcoholism. It is a megaloblastic anemia that can develop within weeks. Peripheral bood smear shows macrocytosis, ovalocytosis, and neutrophils with hypersegmented nuclei.

Answer 36

Acetyl-coA stimulates gluconeogenesis by increasing the activity of pyruvate carboxylase when acetyl-coA is abundant. This regulatory step allows pyruvate to be shunted toward acetyl-CoA production when acetyl-CoA levels are low, preventing the cell from becoming depleted of energy.

Answer 37

For diagnosis of schizoaffective disorder, psychosis must occur in the absence of major mood episodes, but mood episodes must be present for a majority of this lifelong illness. In bipolar disorder and major depression with psychotic features, psychotic symptoms occur exclusively during mood episodes

Answer 38

an immune-mediated disorder of the central nervous system characterized by focal demyelination (plaques). Histologically, plaques contain foci of perivenular inflammatory infiltrates made up primarily of autoreactive T lymphocytes and macrophages. Patchy demyelination occurs followed by astrocyte hyperplasia (glial scarring)

Answer 39

INH is metabolized by acetylation. The speed with which a patient is able to acetylate drugs depends on whether they are genetically "fast" or "slow" aceylators. The presence of fast and slow acetylators within the same population results in a bimodal distribution of the speed of isoniazid metabolism. Slow acetylators are at increased risk of adverse side effects.

Answer 40

represents the number of people who must be treated before 1 additional adverse even occurs. In order to calculate NNH, the absolute risk increase between the treatment and control groups must be known: NNH = 1 / absolute risk increase

Answer 41

can occur with extrinsic compression at the fibular head, resulting in weakness on foot dorsiflexion and eversion. Sensation will also be impaired over the lateral shin, dorsal foot, and between the first and second toes.

Answer 42

Patients with chronic kidney disease often develop normocytic anemia due to erythropoietin (EPO) deficiency. Treatment with recombinant EPO can dramatically improve tissue oxygen delivery and reduce mortality. However, prolonged or high-dose treatment can have serious side effects, most notably increased risk of hypertension and thromboembolism.

Answer 43

caused by immune dysregulation and overproduction of a glomerular permeability factor, which damages podocytes and decreases the anionic properties of the glomerular basement membrane. This results in selective loss of albumin in the urine, in contrast to the nonselective proteinuria seen in other forms of nephrotic syndrome

Answer 44

left atrial and left ventricular end-diastolic pressure. Mitral stenosis leads to an increase in the LA pressure that is reflected as elevated PCWP during pulmonary artery catheterization. Left ventricular filling may be normal, resulting in an increased pressure gradient between the LA and LV during diastole.

Answer 45

contralateral homonymous hemianopia. The macula is often spared because there is collateral circulation from the middle cerebral artery to the occipital pole, the area that processes central vision.

Answer 46

predominantly a disease of children that most frequently affects the long bones. Staph aureus is implicated in most cases secondary to a bacteremic event. Strep pyogenes (group A strep) is the second most common cause of hematogenous osteomyelitis.

Answer 47

characterized by bacterial proliferation in the small bowel, leading to mucosal inflammation with subsequent fermentation of carbohydrates and fat malabsorption; it manifests with diarrhea, abdominal distention, and flatulence. Patients with impaired intestinal peristalsis (eg, systemic sclerosis) are at increased risk. Treatment: oral antibiotics

Answer 48

immediate onset of euphoria, lethargy, ataxia and/or loss of consciousness followed by rapid recovery within 45 minutes. Perioral and perinasal dermatitis (ie, glue sniffer's rash) may be seen in chronic users.

Answer 49

results from impaired function of the von Willebrand factor cleaving protease ADAMTS-13, which causes the accumulation of uncleared vWF multimers that are significantly more prothrombotic. Patients develop diffuse microvascular thrombosis, which leads to thrombocytopenia and microangiopathic hemolytic anemia

Answer 50

Renal artery stenosis (eg, severe hypertension, abdominal bruits) causes decreased renal artery perfusion, which activates the renin-angiotensin-aldosterone system. Increased secretion of renin leads to increased production of angiotensin I and angiotension II, which causes increased peripheral resistance and elevated systemic blood pressure. Increased aldosterone secretion causes increased renal Na reabsorption and K and H excretion, resulting in relative hypokalemia and metabolic alkalosis

Answer 51

early onset, pulsatile GnRH secretion, resulting in increased estrogen production. Estrogens promote bone growth but also epiphyseal plate (ie, growth plate) closure, so without treatment, patients typically have an early growth spurt but a shorter than expected adult height

Answer 52

occurs when the midgut undergoes incomplete physiologic rotation in utero. A life threatening complication of malrotation is midgut volvulus, in which the small intestines twist around the superior mesenteric artery due to the abnormally mobile mesenteric base. Patients have bilious emesis, and an upper gastrointestinal series typically shows proximal small intestinal loops on the right side of the abdomen

Answer 53

Dilation of the left ventricular cavity commonly occurs in response to systolic dysfunction (eg, ischemic heart disease, dilated cardiomyopathy) or certain types of valvular disease (ie, aortic regurg, mitral regurg). Chronic volume overload causes progressive eccentric hypertrophy that eventually leads to reduced ventricular contractility and decompensated heart failure

Answer 54

predominantly block potassium channels and inhibit the outward potassium currents during phase 3 of the cardiac action potential, thereby prolonging repolarization and total action potential duration

Answer 55

often causes nasal congestion, sneezing, rhinorrhea, and conjunctivitis due to an IgE mediated hypersensitivity response. Patients can often distinguish patterns that suggest reactions to specific allergens

Answer 56

optic neuropathy that results in color blindness, central scotoma, and decreased visual acuity. This adverse side effect may be reversed with discontinuation of the drug

Answer 57

muscle pain that is reproducibly caused by exercise and relieved by rest; it occurs due to atherosclerotic stenosis (lipid filled intimal plaques) in the large arteries that prevent sufficient blood flow to exercising muscle. The lower extremities are most commonly affected; however, proximal lesions (ie, aortioilac occlusion) can cause gluteal claudication and/or impotence.

Answer 58

involves an initial downregulation of proangiogenic factors (eg, VEGF) due to hyperoxia following delivery. Subsequently, increased metabolic demand causes relative retinal hypoxia, which stimulates a pathological increase in VEGF leading to aberrant vessel formation. Neonatal oxygen supplementation increases the risk in premature infants.

Answer 59

the cause of bubonic plague, is transmitted primarily by rodent fleas. Manifestations include rapid-onset systemic symptoms (eg, high fever, chills, weakness, headache) and painful, purulent regional lymphadenitis. First line treatment: aminoglycosides, which block bacterial protein synthesis by binding to the 30S ribosomal subunit

Answer 60

an inhertied inborn error of metabolism causing lactic acidosis and neurologic defects. Patients are unable to convert pyruvate to acetyl-CoA, resulting in a shunting of pyruvate to lactic acid. In these patients, metabolism of exclusively ketogenic amino acids (eg, lysine, leucine) can provide energy in the form of acetyl-CoA without increasing lactate production

Answer 61

The urachus is a remnant of the allantois that extends from the bladder to the umbilicus. Failed obliteration of the allantois lumen can result in a patent urachus, which presents with urinary drainage from the umbilicus in the neonate.

Answer 62

Digoxin toxicity presents with nonspecific gastrointestinal (eg, anorexia, nausea, vomiting) and neurological (eg, fatigue, confusion, weakness) symptoms. Changes in color vision are a more specific, but rarer, finding. Life-threatening ventricular arrhythmias are the most serious complication

Answer 63

OR = odds of exposure in cases / odds of exposure in controls OR = ad/bc

Answer 64

Lesch Nysan syndrome (dystonia, self mutilation, hyperuricemia) is caused by a mutation in the gene encoding hypoxanthine-guanine phosphoribosyltransferase (HGPRT). Reduced HGPRT activity leads to impaired purine salvage and increased de novo purine synthesis, a process necessitating increased phosphoribosyl pyrophosphate amidotransferase activity

Answer 65

Incident cases represent new cases diagnosed in a given period of time. Prevalent cases are the total number of cases (both old and new) at a particular point in time. Any treatment that prolongs survival but does not cure the disease will increase prevalence due to an increase in the number of afflicted (but still living) individuals over time.

Answer 66

microglia are the predominant cell in the necrotic area 3-7 days after the onset of ischemia and phagocytize the fragments of neurons, myelin, and necrotic debris.

Answer 67

Congenital hypothyroidism is treated with prompt initiation of levothryoxine in early infancy. Late or inadequate treatment is associated with cognitive (ie, lower intelligence quotient) and neurologic (eg, hearing loss, incoordination) dysfunction.

Answer 68

a dimorphic fungus that exists as a small, ovoid yeast at tissue temperatures. It replicates within macrophages and spreads through the lymphatic and reticuloendothelial system. Immunocompetent patients usually have an asymptomatic pulmonary infection, but those who are immunocompromised (eg, advanced AIDS) can develop disseminated disease to the liver, spleen and bone marrow

Answer 69

The inferior trunk of the brachial plexus carries nerve fibers from the C8 and T1 spinal levels that are responsible for innervating all the intrinsic muscles of the hand (via the median and ulnar nerves). Sudden upward stretching on the arm at the shoulder can damage the inferior trunk resulting in hand clumsiness and total claw hand deformity.

Answer 70

Target cells form when erythrocytes have reduced cell volume (eg, thalassemia, iron def) or excessive membrane (eg, obstructive liver disease, postsplenectomy). Patients who undergo splenectomy usually develop target cells because the spleen is the primary organ that prunes excessive red cell membrane

Answer 71

Alpha-2 adrenergic receptors inhibit insulin secretion, and beta 2 adrenergic receptors stimulate insulin secretion. The alpha-2 mediated inhibitory effect is generally predominant, causing sympathetic stimulation to lead to overall inhibition of insulin secretion.

Answer 72

presents with episodic flushing, secretory diarrhea, and wheezing. It can lead to pathognomonic plaque-like deposits of fibrous tissue on the right-sided endocardium, causing tricuspid regurgitation and right sided heart failure. Elevated 24 hour urinary 5-hydroxyindoleacetic acid can confirm the diagnosis

Answer 73

Vitamin B6 (pyridoxine) is a required cofactor for the enzyme 5-aminolevulinate synthase, which catalyzes the first, rate limiting step in porphurin synthesis. Defects in this enzyme causes X-linked sideroblastic anemia. Aminolevulinic acid synthetase converts succinyl CoA to aminolevulinic acid using b6 as a cofactor.

Answer 74

autoimmune insulitis with progressive beta cell loss

Answer 75

Insulin resistance accompanied by relative insulin deficiency