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Cardiovascular and Respiratory Systems—Cardiology and Pulmonology

Questions

386. A 22-year-old Hispanic male college student with a normal medical history collapses during an intramural soccer game. His friends think he is joking, then notice his blue color and call an ambulance. Resuscitation is unsuccessful and the autopsy reveals dilated cardiac chambers with increased thickness of the ventricular walls (hypertrophic, dilated cardiomyopathy). Electron microscopy of the heart muscle shows abnormal thick filaments, and the pathologist suspects a genetic disorder. Genes encoding which of the following proteins would be most likely to reveal the causative mutation?

a. Keratin

b. Lamin

c. Myosin

d. Peripherin

e. Vimentin

387. A 65-year-old obese Caucasian male presents with pain radiating down the left arm and shortness of breath. A serum lactate dehydrogenase (LDH) level is obtained to evaluate possible myocardial infarction, and its activity is only slightly elevated. Shortly thereafter the laboratory calls, saying that a more detailed analysis of LDH does suggest myocardial damage. The managing physician knows that lactate dehydrogenase is composed of two different polypeptide chains arranged in the form of a tetramer. Which of the following is the likely correlation between LDH measures and the likelihood of myocardial infarction?

a. LDH is an enzyme specific to the endocardium.

b. LDH is mainly localized in liver, and its elevation in cardiac disease occurs because of heart failure.

c. LDH isozymes are composed of different subunit combinations, some released during inflammation following heart attacks.

d. LDH isozymes are composed of different subunit combinations, some specific for heart and released with myocardial damage.

e. LDH isozymes are composed of different subunit combinations, some specific for vascular endothelium and released with infarction.

388. A 28-year-old Caucasian female presents to her obstetrician at week 23 of pregnancy, complaining of extreme fatigue. Evaluations of serum iron level and fetal well-being are normal, but the nurse notices a weak and irregular pulse. Chest x-ray reveals an enlarged heart and the electrocardiogram reveals a short PR interval and prolonged QRS interval, including a slurred-up stroke of the R wave called a delta wave. The ECG is read as showing Wolff-Parkinson-White syndrome, a condition with risks for paroxysmal supraventricular tachycardia. The physician considers treatment with calcium channel regulators, balancing their risks to mother and fetus. Contraction of cardiac and skeletal muscle is initiated by the binding of calcium to which of the following substances?

a. Actin

b. Actomyosin

c. Myosin

d. Tropomyosin

e. Troponin

389. A 43-year-old Caucasian male is rushed to the hospital with crushing chest pain radiating to his left arm and a probable heart attack. His cholesterol is 420 mg/dL despite prior use of statin medicines and he has familial hypercholesterolemia (MIM*143890). Which of the following treatments should be considered?

a. A platelet transfusion

b. Heparin infusion

c. Thrombin infusion

d. Fibrinogen infusion

e. Tissue plasminogen activator infusion

390. After a term uncomplicated gestation, normal delivery, and unremarkable nursery stay, a 10-day-old African American girl is readmitted to the hospital because of poor feeding, weight loss, and rapid heart rate. Antibiotics are started as a precaution against sepsis, and initial testing indicates an unusual echocardiogram with a very short PR interval and a large heart on x-ray. Initial concern about a cardiac arrhythmia changes when a large tongue is noted, causing concern about glycogen storage disease type II (Pompe disease—MIM*232300). Which of the following best explains why Pompe disease is more severe and lethal compared to other glycogen storage diseases?

a. The deficiency is a degradative rather than synthetic enzyme

b. The deficiency involves a liver enzyme

c. The deficiency involves a lysosomal enzyme

d. The deficiency causes associated neutropenia

e. The deficiency involves a serum enzyme

391. A 35-year-old African American male has avoided health care but presents to his physician because his father recently died of a heart attack at age 55. The physician obtains a serum cholesterol of 320 mg/dL and a serum lipoprotein profile. Which of the following describes the order of lipoproteins from lowest to highest density along with the likely levels (↑ = elevated, ↓ = decreased) in this patient if his blood is drawn 30 minutes after breakfast?

a. HDLs ↓ LDLs ↑ IDLs ↑ VLDLs ↑ chylomicrons ↓

b. Chylomicrons ↑ VLDLs ↑ IDLs ↑ LDLs ↑ HDLs ↓

c. VLDLs ↓ IDLs ↓ LDLs ↓ chylomicrons ↓ HDLs ↓

d. HDLs ↑ Chylomicrons ↑ IDLs ↑ VLDLs T LDLs ↑

e. LDLs ↑ VLDLs ↑ IDLs ↑ chylomicrons ↑ HDLs ↑

392. Which of the following best explains why statin therapy is effective for individuals with hypercholesterolemia?

a. Statins inhibit HMG-CoA reductase, a key regulator of cholesterol synthesis.

b. Statins inhibit HMG-CoA synthase, key step for synthesis of mevalonate that inhibits fatty acid synthesis.

c. Stains stimulate thiolase, thus making more malonyl-CoA for inhibition of the tricarboxylic acid cycle.

d. Statins bind to LDL receptor, displacing cholesterol and inhibiting cholesterol synthesis.

e. Statins stimulate synthesis of trans-unsaturated fatty acids.

393. Coronary artery disease is a multifactorial disorder involving occlusion of the coronary artery with atherosclerotic plaques. Several Mendelian disorders affecting lipid metabolism increase susceptibility for heart attacks, while environmental factors include smoking and high-fat diets. A 45-year-old Caucasian male has a mild heart attack and is placed on diet and mevastatin therapy. Which of the following will be the most likely result of this therapy?

a. Low blood glucose

b. Low blood LDLs

c. High blood cholesterol

d. High blood glucose

e. Low oxidation of fatty acids

394. A 6-year-old African American boy is evaluated for respiratory distress from refractory asthma and improves after albuterol inhalation therapy He is discharged with instructions to continue albuterol nebulizer treatments and is given 2 mg/kg oral prednisolone as a 5-day burst. This therapy avoids the side effects of chronic steroid therapy (obesity, hypertension, and shock susceptibility) by using short bursts of oral therapy or inhaled steroids that affect nasal/bronchial membranes without systemic absorption. Steroid therapies impact which of the following processes?

a. Conversion of membrane arachidonyl-triglyceride to arachidonic acid

b. Conversion of arachidonic acid to leukotrienes

c. Conversion of arachidonic acid to prostaglandins

d. Peroxidation of prostaglandin precursor

e. Dietary absorption of arachidonic acid

395. Congestive heart failure can be caused by intrinsic defects of the heart muscle/valves or by pumping against increased pressure as with prolonged hypertension. Which of the following effects of the steroid digitalis is observed after treatment of congestive heart failure?

a. Decrease in cytosolic sodium levels

b. Inhibition of Na⁺, K⁺-ATPase

c. Decrease in the force of heart muscle contraction

d. Stimulation of the plasma membrane ion pump

e. Decrease in cytosolic calcium

396. A 40-year-old Caucasian female is stung by a bee and rushed into the emergency room with a variety of symptoms including increasing difficulty in breathing due to nasal and bronchial constriction. Although your subsequent treatment is to block the effects of histamine and other acute-phase reactants released by most cells, you must also block the slow-reacting substance of anaphylaxis (SRS-A), which is the most potent constrictor of the muscles enveloping the bronchial passages. An SRS-A is composed of which of the following?

a. Thromboxanes

b. Interleukins

c. Complement

d. Leukotrienes

e. Prostaglandins

397. A 23-year-old Caucasian female with cystic fibrosis (MIM*219700) marries her first cousin. What is the risk that their first child will have cystic fibrosis?

a. ½

b. ¼

c. ¹/8

d. ¹/16

e. ¹/32

398. A 23-year-old Caucasian male whose brother has cystic fibrosis (MIM*219700) wants to know his risk of having an affected child. The prevalence of cystic fibrosis is 1 in 1600 individuals. Which of the following is the risk in this case?

a. ¹/8

b. ¹/16

c. ¹/60

d. ¹/120

e. ¹/256

399. A 22-year-old Caucasian female who married her first cousin wants to know the risk of having a child with cystic fibrosis (MIM*219700) because her grandmother, who is also her husband’s grandmother, died of cystic fibrosis. Which of the following is her risk?

a. ¹/8

b. ¹/16

c. ¹/60

d. ¹/120

e. ¹/256

400. A 32-year-old Caucasian male of Scandinavian origin exhibits increased fatigue with shortness of breath during his usual jogging routine. His physician suspects early-onset emphysema and performs protein electrophoresis for analysis of α₁-antitrypsin (AAT) deficiency (MIM*107400). The result shows two electrophoretic bands that react with AAT, one at the normal position, and one at an abnormal position. Which of the following best describes this result?

a. The male is homozygous and has normal AAT activity

b. The male is heterozygous and has normal AAT activity

c. The male is homozygous and has deficient AAT activity

d. The male is homozygous and has an altered AAT protein

e. The male is heterozygous and has an altered AAT protein

401. A 45-year-old male is hospitalized for treatment of myocardial infarction. His father and a paternal uncle also had heart attacks at an early age. His cholesterol is elevated, and lipoprotein electrophoresis demonstrates an abnormally high ratio of low- to high-density lipoproteins (LDL to HDL). Which of the following is the most likely explanation for this problem?

a. Mutant HDL is not responding to high cholesterol levels.

b. Mutant LDL is not responding to high cholesterol levels.

c. Mutant caveolae proteins are not responding to high cholesterol levels.

d. Mutant LDL receptors are deficient in cholesterol uptake.

e. Intracellular cholesterol is increasing the number of LDL receptors.

402. A patient with myocardial infarction is treated with nitroglycerin to dilate his coronary arteries. Which of the following best describes the action of nitroglycerin?

a. Methylation occurs to produce S-adenosylmethionine.

b. GTP hydrolysis accomplishes oxidation of LDL proteins.

c. Arginine is converted to a neurotransmitter that activates guanyl cyclase.

d. Acetyl-CoA and choline are condensed to form a neurotransmitter.

e. Tyrosine is converted to serotonin.

403. A male is evaluated for mild liver disease, arthritis, fatigue, and grayish skin pigmentation. A liver biopsy shows marked increase in iron. Which of the following laboratory values is most likely?

a. Low serum iron

b. High serum copper

c. Low saturation of transferrin

d. High serum ferritin

e. Low serum haptoglobin

404. The regulation of transferrin receptors is studied in tissue culture. There is increased synthesis of transferrin receptor protein with no changes in transferrin mRNA transcription. Which of the following is the most plausible explanation?

a. Change in amounts or types of transcription factors

b. Allosteric regulation of transferrin receptor function

c. Activation of transferrin receptor function by a protein kinase

d. Stabilization of transferrin mRNA

e. Increased GTP levels to accelerate protein elongation

405. The development of DNase therapy has dramatically improved survival and therapy of lung infections in children with cystic fibrosis (MIM*219700). Early diagnosis also allows supplementation of missing pancreatic enzymes with better lipid absorption and improved IQ measures. Over 97 common mutant alleles for Caucasians with cystic fibrosis have now been characterized at the DNA level, allowing screening of pregnant couples with high sensitivity. Which of the following techniques is used to screen couples and newborns for cystic fibrosis?

a. Fluorescent in situ hybridization (FISH) for deletions surrounding the disease locus

b. Subtelomeric FISH analysis

c. Multiplex PCR with high sensitivity

d. Southern analysis to display mutant alleles

e. Comparative genomic hybridization (CGH)-microarray analysis

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