1. A 45-year-old man who was diagnosed with small cell carcinoma of the lung 1 week ago comes to the physician to discuss treatment. The physician recommends induction chemotherapy that includes cyclophosphamide, doxorubicin, vincristine, and cisplatin. He will be pretreated with dexamethasone and ondansetron as antiemetics and mesna to help prevent cystitis. Which of the following drugs has the greatest potential to produce both nephrotoxicity and ototoxicity in this patient?

O A) Cisplatin O B) Cyclophosphamide O C) Doxorubicin O D) Ondansetron O E) Vincristine

2. A 39-year-old woman with AIDS develops headaches and fever. Budding yeasts are present in her cerebrospinal fluid. The virulence of the infecting organism is due to which of the following?

O A) Capsular polysaccharide O B) Cell wall sterols O C) Complement-inhibiting ligands O D) Mannan-binding lectins O E) Pseudohyphae

3. A 50-year-old man with type 2 diabetes mellitus and hypertension comes to the physician because of puffiness of his face and hands, fatigue, and a 5-kg (11 -lb) weight gain during the past week. He had a sore throat and coryza2 weeks ago that resolved after 2 days. He is 175 cm (5 ft 9 in) tall and now weighs 123 kg(270 lb); BMI is 40 kg/m2 His temperature is 37.2°C (99°F), pulse is 90/min, respirations are 20/min, and blood pressure is 160/100 mm Hg. Physical examination shows generalized edema, most marked in the periorbital areas, and pitting edema of the lower extremities. Laboratory studies show an increased serum total cholesterol concentration, proteinuria, and no hematuria or casts. A photomicrograph of a renal biopsy specimen is shown. Which of the following is the most likely diagnosis?

O A) Diabetic glomerulosclerosis O B) Membranous glomerulonephritis O C) Minimal change disease O D) Poststreptococcal glomerulonephritis O E) Rapidly progressive glomerulonephritis

4. A 54-year-old woman comes to the physician for a routine examination. She has had symptoms of menopause for approximately 15 months. She inquires about the risks and benefits of combined hormone replacement therapy. She says she has obtained some information from a Web site on the Internet and understands the effects of estrogen. However, she is unsure of the purpose of progesterone in the therapy regimen. She is provided with literature from the Women's Health Initiative trial and the Heart and Estrogen/Progestin Replacement Study. After fully explaining the results of the research, which of the following is the most appropriate response by the physician regarding the beneficial effects of progesterone?

O A) Decreases thromboembolic disease O B) Decreases vaginal atrophy O C) Increases serum HDL-cholesterol concentration O D) Prevents endometrial hyperplasia O E) Prevents osteoporosis

5. A 16-year-old girl comes to the physician because of a 10-year history of a lesion on her left arm. Physical examination shows a 1-cm pigmented lesion on the left forearm. Following excision, the edges of the defect are opposed, and the wound is sutured. Increased mitotic activity of which of the following is most likely to reestablish epidermal continuity in this patient?

O A) Basal cells O B) Corneocytes O C) Langerhans cells O D) Macrophages O E) Melanocytes O F) Merkel cells

6. A 44-year-old woman comes to the physician for a follow-up examination after two separate Pap smears showed atypical squamous cells of undetermined significance. Results of a molecular diagnostic test show the presence of the viral E6 protein of human papillomavirus. This protein promotes cell growth and malignancy by which of the following actions?

O A) Decrease in tyrosine kinase activityO B) Degradation of p53 tumor suppressor proteinO C) Inactivation of a DNA mismatch repair geneO D) Increase in platelet-derived growth factor concentrationO E) Increase in telomerase activityO F) Increase in vascular endothelial growth factor concentration

7. A 58-year-old man comes to the physician because of a 6-month history of a gurgling noise in his throat as he eats, which often requires repeated coughing and throat clearing to eradicate. He occasionally regurgitates undigested food 1 hour after eating. He has a 2-year history of well-controlled type 2 diabetes mellitus and a 6-month history of intermittent mild dysphagia and progressive halitosis. He has not had any weight loss. His vital signs are within normal limits. Physical examination shows no abnormalities. Which of the following is the most likely diagnosis?

O A) Barrett esophagus O B) Diffuse esophageal spasm O C) Esophageal cancer O D) Gastroesophageal reflux disease O E) Zenker diverticulum

8. A 44-year-old man comes to the physician to discuss the results of electromyography (EMG) conducted 1 week ago. He has had progressive muscle wasting, frequent muscle twitches at rest, mild difficulty swallowing, and a 6.8-kg (15-lb) weight loss during the past3 months. He has been concerned that this might represent a serious illness. Physical examination shows atrophy of the muscles of the right upper extremity and left lower extremity, and brisk deep tendon reflexes. The results of the EMG are compatible with amyotrophic lateral sclerosis (ALS). Which of the following is the most appropriate way to initiate a discussion about these results with this patient?

O A) "I'd like to talk to you about your EMG, but I want to wait until your wife can be present. Can you return later this week with her?"

O B) "You do have a very serious muscle disease called ALS. This cannot be cured, but I will be here to help you with everything I can. Have you heard of ALS?"

O C) "You seem to have a significant muscle disease, and I am going to start you on medication right away. Have you thought about a living will or power of attorney for medical affairs?"

O D) "Your EMG shows diffuse denervation and four-extremity increased amplitude, which confirms our worst suspicions. You have ALS."

O E) "Your EMG shows diffuse muscle disease, and I will refer you to a specialist. In the meantime, I'd like to provide you with a Web site that offers lots of helpful advice about living with the disease."

9. A previously healthy 55-year-old man comes to the emergency department because of a 3-hour history of chest pressure. He states, "My chest is burning. I drank some whole milk, but it didn't help." His father died suddenly at the age of 45 years. His pulse is 95/min, and blood pressure is 156/96 mm Hg. Physical examination shows no jugular venous distention. Crackles are heard one quarter of the way up both lung fields posteriorly. Cardiac examination shows a soft S4 gallop most prominent at the apex. An ECG shows ST- segment elevation in leads I, aVL, and V5 through V6 without PR depression. Initial therapy with antiplatelet agents administered prior to arrival fails to resolve the acute ECG changes. Which of the following agents is the most appropriate next pharmacotherapy?

O A) Clopidogrel O B) Protein C O C) Simvastatin O D) Tissue plasminogen activator O E) Warfarin

10. A 50-year-old man comes to the physician for a follow-up examination. One year ago, he was admitted to the hospital for treatment acute respiratory distress syndrome (ARDS) associated with acute pancreatitis. Which of the following is most likely to be found in this patient with resolved ARDS?

O A) Decreased alveolar dead space:tidal volume O B) Decreased concentrations of surfactant protein D O C) Decreased diffusing capacity for carbon monoxide (DLC0)O D) Increased concentrations of neutrophils in bronchoalveolar lavage fluid O E) Increased concentrations of surfactant protein D O F) Increased pulmonary capillary blood volume

11. A 20-month-old boy is brought to the physician by his mother because she is concerned about his language development. His mother says, "I don't understand. His 4-year-old sister had no problems with speech when she was his age." He is able to make some sounds, including "b" and "p" spontaneously, but he seems slow to imitate words the parents say. He is active, able to run a few steps, and can recognize shapes and do simple puzzles. He is at the 60th percentile for length and weight, and 75th percentile for head circumference. He is friendly and cooperative and has good eye contact. Physical examination shows no abnormalities. Which of the following is the most appropriate initial statement by the physician?

O A) "I recommend that he undergo a hearing screening as soon as possible."O B) "I wouldn't worry. Boys often speak later than girls do."O C) "I'm going to schedule him for an MRI of the brain to exclude hydrocephalus."O D) "You should give him things only if he attempts to ask for them."O E) "You should have him evaluated by a child psychologist for possible autistic disorder."

12. A 25-year-old woman comes to the physician because she has not had a menstrual period for 1 year. Menses began at age 14 years, and until the past year have occurred every 28 days and lasted 5 days. She does not have any children but would like to start a family. Examination is unremarkable. A pregnancy test is negative. Laboratory studies show an increased serum prolactin concentration and normal serum thyroid-stimulating hormone and thyroxine (T4) concentrations. Cranial imaging shows a pituitary microadenoma. Which of the following agents is likely to be most effective in achieving fertility?

O A) Dopamine agonist O B) Estrogen agonist O C) Gonadotropin agonist O D) Progesterone agonist O E) Testosterone agonist

13. A previously healthy 4-year-old boy is brought to the emergency department because of generalized tonic-clonic seizures for the past 30 minutes. Which of the following drug targets most likely mediates the effect of the most appropriate drug?

O A) G protein-coupled receptor O B) Ligand-gated ion channels O C) Membrane-spanning enzymes O D) Neurotransmitter transporters O E) Receptor tyrosine kinase

14 During a phase 1 clinical trial, healthy volunteers are pretreated with an intravenous infusion of angiotensin II at a constant dose. They then receive a new anti hypertensive drug (Drug A) for 30 minutes in increasing doses. The dose-response curve is shown. One week later, the volunteers are pretreated with one dose of another drug (Drug B), and the same increasing dose infusions of Drug A are repeated. One week later, the same infusion of Drug A is given after a tenfold higher dose of Drug B. According to the data shown, which of the following best describes Drug B in relation to Drug A?

O A) Competitive antagonist O B) Full agonist O C) Noncompetitive antagonist O D) Partial agonist O E) Potentiator

-Log Dose A

15. The binding of a ligand to a membrane-bound receptor can result in a conformational change in the receptor leading to activation of an enzyme such as adenylyl cyclase. This conformational change is initiated by a series of events that requires the binding of which of the following nucleotides?

O A) ADP O B) AMP O C) ATP O D ) GDP O E) GTP

i. A 76-year-old man comes to the physician because of shortness of breath for 3 weeks. He has a 20-year history of hypertension. His temperature is 37°C (98.6°F), pulse is 118/min, respirations are 22/min, and blood pressure is 108/52 mm Hg. Bilateral crackles are heard on auscultation of the chest. Cardiac examination shows a normal S, and S2; an S3is heard. The point of maximal impulse is located at the sixth left intercostal space at the anterior axillary line. Which of the following sets of hemodynamic values is most likely in this patient?

O A) O B) OC) OD) O E ) O F)

Left Ventricular Stroke Volume

DecreasedDecreasedDecreasedIncreasedIncreasedIncreased

17. A 36-year-old man with acute lymphocytic leukemia comes to the physician because of a 2-hour history of fever and several scattered, dark skin lesions. He was treated with chemotherapy 10 days ago. He appears lethargic. His temperature is 39°C (102.2°F), pulse is 110/min, respirations are 32/min, and blood pressure is 90/48 mm Hg. Physical examination shows four black, round, papular lesions with a rim of erythema over the lower extremities. His leukocyte count is 1000/mm3 (8% segmented neutrophils and 92% lymphocytes). A blood culture grows gram-negative rods. Which of the following is most likely responsible for this patient's hypotension?

O A) Bradykinin causing increased capillary oncotic pressureO B) Increased serum concentrations of C8 and C9 giving rise to release of histamine from mast cells and basophils O C) Lipopolysaccharide stimulating production of tumor necrosis factor O D) Lipoteichoic acid activating synthesis of interleukin-1 (IL-1) and interferon-y O E) Proteoglycan activating maturation of IL-1, IL-6, and IL-8

18. A 52-year-old man with an esophageal tumor near the gastroesophageal junction is scheduled for a total esophagectomy including anastomosis of the stomach to the lower pharynx. During this procedure, which of the following nerves must be severed?

O A) Left recurrent laryngeal O B) PhrenicO C) Right recurrent laryngeal O D) Superior laryngeal O E) Thoracic splanchnic O F) Vagus

19. A 75-year-old woman begins treatment with several drugs for osteoporosis. Two weeks later, she develops a burning sensation in her chest and throat daily approximately 2 hours after taking her medications. Which of the following medications is the most likely cause of the development of the burning sensation in this patient?

O A) Alendronate O B) Calcitonin O C) Raloxifene O D) Sodium fluoride O E) Vitamin D

20. A 2-month-old girl has asymmetric gluteal folds. If untreated, the underlying pelvic condition will most likely progress to an erosive arthropathy. Which of the following is the most likely diagnosis?

O A) Dislocation O B) Fasciitis O C) Ganglion O D) Myositis ossificans O E) Sprain O F) Strain

21. A 71-year-old man comes to the physician because of a 4-month history of decreased force and size of his urine stream. Rectal examination shows a diffusely enlarged prostate. Urinalysis shows microscopic blood. Cystoscopy shows hypertrophy and thickening of the bladder wall. Without treatment, this patient is at greatest risk for which of the following?

O A) Bladder transitional cell carcinoma O B) Renal papillary necrosis O C) Urethral diverticulum O D) Urethral stricture O E) Urinary tract infection

22. A new test for coronary artery disease is reported to have a sensitivity of 90% and a specificity of 95% in a matched case-control study. A validation study is performed in 1000 patients comparing this new test to the gold standard test: coronary artery angiography. Results are shown:

Present AbsentTest Positive I 80 I 90 I 170

Negative I 20 I 810 1 830100 900 1000

Which of the following is the specificity in this study?

O A ) 20/80 = 25%O B) 80/90 = 89%O C ) 80/100 = 80%O D ) 80/170 = 47%O E) 100/1000= 10%O F) 810/830 = 98%OG) 810/900 = 90%

23. A 49-year-old man comes to the physician because of a rash and diarrhea for 3 days. He underwent bone marrow transplantation for acute myelogenous leukemia 40 days ago. Physical examination shows an erythematous maculopapular rash and jaundice. Serum studies show a total bilirubin concentration of 2 mg/dL and AST activity of 32 U/L. Which of the following types of hypersensitivity reaction is the most likely cause of the findings in this patient?

O A) Antibody-mediated O B) Cell-mediated O C) Immediate O D) Immune complex

24. A 19-year-old college student is brought to the emergency department by campus police after he was found skateboarding nude around campus with a bucket of fluorescent paint and a brush. The police report that he was emblazoning all the sidewalks and parking lots with literary phrases. He is a creative writing major, and his friends describe him as an intelligent, happy, fun-loving, popular student who avoids drugs and alcohol. His roommate says that he recently had a burst of energy. He has been awake around the clock, writing furiously at his desk, and announcing that he is "onto something big with this novel." He has no history of psychiatric illness; family history is unknown. Toxicology screening is negative, and serum thyroid-stimulating hormone concentration is within normal limits. Which of the following is the most likely diagnosis?

O A) Adjustment disorder O B) Bipolar disorder O C) DeliriumO D) Major depressive disorder O E) Personality disorder, not otherwise specified O F) Schizophrenia

25. A 36-year-old man comes to the physician because of pain in his right lower leg for 3 days. He recently increased his running routine from 12 to 24 miles per week. Physical examination shows tenderness of the right lower extremity. An x-ray of the lower extremity shows a stress fracture of the right lower tibia. Which of the following is most likely increased in this patient?

O A) Osteoblast activity at the fracture O B) Serum calcium concentration O C) Serum magnesium concentration O D) Serum parathyroid hormone concentration O E) Serum phosphorus concentration O F) Serum vitamin D concentration

26. A 50-year-old man comes to the physician for a routine examination. There are no orthostatic changes in pulse or blood pressure. Physical examination shows no abnormalities. Laboratory studies show a hemoglobin concentration of 12 g/dL and hematocrit of 36%. Six months ago, his hemoglobin concentration was 15 g/dL, and hematocrit was 46%. Test of the stool for occult blood is positive. The physician concludes that an increased delivery of oxygen to the tissues has prevented the emergence of symptoms of anemia. Which of the following events most likely increased the oxygen delivery in this patient?

O A) Decrease in Ca2* concentration O B ) Decrease in H-concentration O C) Decrease in temperatureO D) Increase in erythrocyte 2,3-bisphosphoglycerate concentration O E) Increase in glucose concentration

. An investigator develops an indirect immunofluorescent immunoassay for detecting Chlamydophila psittaci in respiratory secretions. Polyclonal antisera and monoclonal antibody are generated against a single killed strain of C. psittaci. An initial enzyme immunoassay with the immunogenic strain shows comparable results with the polyclonal antisera or the monoclonal antibody. In a clinical setting, however, it is found that the polyclonal antisera are substantially more sensitive than the monoclonal antibody for detecting C. psittaci infection. Which of the following best explains this difference in sensitivity?

A) The affinity of the monoclonal antibody for its complementary epitope is lower than that of the polyclonal antiseraB) The avidity of the monoclonal antibody for its complementary epitope is lower than that of the polyclonal antiseraC) The fluorescein isothiocyanate label does not bind as tightly to the monoclonal antibody as it does to the polyclonal antiseraD) The greater diversity of epitopes recognized by the polyclonal antisera permits identification of strains not recognized by the

monoclonal antibodyE) The monoclonal antibody lacks portions of the Fc region critical for recognition by anti-IgG antibodies in this indirect assay

28. A 26-year-old man with Hodgkin disease comes to the physician to receive his second cycle of combination chemotherapy. Ten days after receiving his first cycle, he had a fever and leukocyte count of 800/mm3. He recovered after appropriate treatment. Which of the following is the most appropriate pharmacotherapy to add to this patient's second cycle of chemotherapy?

O A) Erythropoietin O B) Filgrastim O C) lnterleukin-7 (IL-7)O D ) IL-11 O E) Thrombopoietin

29. A 75-year-old man comes to the physician because of a 2-week history of moderate low back pain. Physical examination shows tenderness of the back and down each lower extremity on bending forward; there are no neuromuscular abnormalities. Rectal examination shows an enlarged prostate. Serum studies show a markedly increased prostate-specific antigen concentration. An x- ray of the spine shows vertebral collapse at L1 and patchy areas of increased density, consistent with osteoblastic metastases. Vertebroplasty is done to relieve the patient's pain, and a biopsy specimen of the damaged vertebra is obtained. Histologic examination of the biopsy specimen is most likely to show which of the following findings?

O A) Aggregates of proliferating plasma cells and plasmablasts O B) Nests of epithelial cells joined by intercellular bridges and containing keratin pearls O C) Pleomorphic epithelial cells forming duct-like structures O D) Sheets of small oval- to spindle-shaped basophilic cellsO E) Sheets of uniform cells divided into lobules by fine fibrous septa containing lymphocytes

30. A 23-year-old woman comes to the physician because of a 6-month history of lethargy and fatigue; she has had a 9-kg (20-lb) weight loss during this period. Physical examination shows a generalized increase in pigmentation of the skin and buccal mucosa. Her blood pressure is 104/70 mm Hg while supine and 86/60 mm Hg while standing. Serum studies show:

Na* 129 mEq/LK* 5.7 mEq/LGlucose 64 mg/dLAldosterone 0.5 ng/dL (N=3—10)

Which of the following changes in renal function is a direct result of the abnormal serum aldosterone concentration in this patient?

O A) Decreased glomerular filtration rate O B) Increased renin secretion O C) Increased sodium in the urine O D) Increased water resorption from the distal tubules O E) Proteinuria

31. A 1-year-old girl is brought to the emergency department by her parents because of fever and irritability for 6 hours. She was recently adopted and did not receive routine childhood immunizations. Her temperature is 39.4°C (103°F). Physical examination shows nuchal rigidity. Cerebrospinal fluid (CSF) analysis shows a decreased glucose concentration, increased protein concentration, and many segmented neutrophils. Culture of CSF grows a gram-negative, rod-shaped organism on a chocolate agar plate. The vaccine that could have prevented this patient's disease produces protective antibodies to which of the following structural components of the bacterium?

O A) Capsule O B) Cell membrane O C) Lipopolysaccharide O D) Peptidoglycan O E) Pili

32. An 8-year-old boy is brought to the physician by his parents because of a 3-month history of episodes of unusual behavior that interfere with his performance at school. His teacher told the parents that he suddenly stops what he is doing for a few seconds and stares into space. The episodes start and end abruptly. Physical and neurologic examinations show no abnormalities. Which of the following mechanisms is the most likely cause of these episodes?

O A) Cortical inhibition of thalamic neurons O B) Decreased dopaminergic inputs to cortical neurons O C) Impaired activity of pontine neurons O D) Spreading depression of cortical neurons O E) Synchronized discharge of thalamocortical neurons

33. A 16-year-old boy is brought to the emergency department because of intermittent testicular pain during the past 2 hours. Physical examination shows a swollen, red scrotum. Testicular torsion is suspected in this patient. The most appropriate diagnostic test is Doppler ultrasound to show the blood flow to the testicle from which of the following arteries?

O A) Artery of the ductus deferens O B) Cremasteric artery O C) Direct branch from the aorta O D) External pudendal artery

34. A 40-year-old man is at risk for an autosomal dominant neurodegenerative disorder caused by trinucleotide repeat expansion.Molecular diagnostic analysis of his DNA shows a normal allele and an allele with expansion of codon CAG encoding glutamine within exon 2 of the responsible gene as shown. Risk estimates for various CAG repeat numbers are shown in the graph. Based on this information, which of the following is the best estimate of the likelihood that this man will develop this disorder?

34. A 40-year-old man is at risk for an autosomal dominant neurodegenerative disorder caused by trinucleotide repeat expansion.Molecular diagnostic analysis of his DNA shows a normal allele and an allele with expansion of codon CAG encoding glutamine within exon 2 of the responsible gene as shown. Risk estimates for various CAG repeat numbers are shown in the graph. Based on this information, which of the following is the best estimate of the likelihood that this man will develop this disorder?

35. A 40-year-old man comes to the emergency department for treatment of a deep wound on his left leg that he sustained while working at a construction site in a rural area 2 days ago. Examination of the left lower extremity shows a 12-cm, tender, edematous wound that is crepitant upon palpation. A blood-tinged exudate can be expressed from the wound. A Gram stain of the exudate shows gram- positive rods. The wound is debrided, and immediate treatment with an antibiotic is started. Which of the following methods is most appropriate to successfully culture the causal organism?

O A) Incubation aerobically at 42°C O B) Incubation at 30°C with C02 O C) Incubation under strict anaerobic conditions O D) Use of chocolate agar containing antibiotics O E) Use of lactose-MacConkey medium

37. A healthy 22-year-old man with normal kidney function increases his sodium intake from 120 mEq/dayto 300 mEq/dayfor 3 months. Which of the following is most likely to be increased in this man?

O A) Plasma aldosterone concentration O B) Plasma angiotensin II concentration O C) Plasma volume O D) Potassium excretion O E) Renin release

38. A 65-year-old man is brought to the emergency department because of shortness of breath for 12 hours. He is in moderate distress. His temperature is 36.7°C (98°F), pulse is 110/min, respirations are 22/min, and blood pressure is 90/40 mm Hg. Physical examination shows pallor and 2+ pitting ankle edema. Crackles are heard on auscultation of the chest. An ECG shows no abnormalities. Cardiac enzyme activities are normal. Which of the following changes in renal function is most likely in this patient?

O A) Decreased Ch reabsorption O B ) DecreasedNa*reabsorption O C) Increased glomerular filtration rate O D) Increased K* excretion O E) Increased renal blood flow

39. A 55-year-old man comes to the emergency department 2 hours after he fell on his right wrist. He has a 1 -year history of coronary artery disease and a 2-year history of heartburn. Examination of the right wrist shows exquisite tenderness to palpation and swelling. The patient asks, "Do you think you could prescribe celecoxib for the pain? I've heard that it won't upset my stomach like aspirin does." The physician is reluctant to prescribe this drug because other drugs in the same category have been associated with increased risk for myocardial infarction. This increased risk is most likely caused by which of the following mechanisms of action?

O A) Greater inhibition of cyclooxygenase-1 (COX-1) than COX-2 enzymes O B) Inhibition of COX-2 enzyme in gastric epithelial cellsO C) Inhibition of lipoxygenase preventing the formation of leukotriene D4 and leukotriene C4 O D) Inhibition of prostacyclin (PGIj) formation without inhibition of thromboxane A2 in platelets O E) Inhibition of prostaglandin E2formation

40. When a patient is asked to look to the right, the right eye moves appropriately, but the left eye does not cross the midline of its optic axis. When the patient is asked to look upward, both eyes move appropriately. Which of the following neuroanatomic sites is most likely involved?

O A) Oculomotor nerve O B) Abducens nerve O C) Vestibular nerve O 0) Medial longitudinal fasciculus O E) Vertical gaze center

41. A 73-year-old woman comes to the physician for a follow-up examination. Six months ago, she was diagnosed with metastatic small cell lung carcinoma but declined treatment. Physical examination today shows no cardiopulmonary abnormalities. A chest x-ray shows widening of the angle between the right and left main stem bronchus, with the orientation of the right main stem bronchus being more horizontal. The primary lesion has not increased in size. Which of the following best explains the current x-ray findings in this patient?

O A) Dilated right atrial appendage O B) Enlarging subcarinal lymph node O C) Left perihilar lymphadenopathy O D) Malignant pericardial effusion O E) Volume loss of the left upper lobe of the lung

42. A male newborn has an abnormal blood thyroid-stimulating hormone (TSH) concentration at birth. Physical examination shows an anterior cervical mass high in the neck; the thyroid gland is not palpable. Serum studies show a TSH concentration of 30 viU/mL (N<5), thyroxine (T4) concentration less than 3 vig/dL (N=4—12), and triiodothyronine (T3) concentration of 65 ng/dL (N=80—100). Which of the following is the most likely cause of these findings?

O A) Anti-TSH-receptor antibody O B) Lingual thyroid O C) Negative iodine balance O D) Sodium/iodine symporter gene mutation O E) Thyroid carcinoma

43. A 14-year-old boy is brought to the physician by his mother because of a 3-month history of severe blemishes on his face and back that have been increasing in number. His mother has bought many over-the-counter medications for the acne, but he has not used any of them. Physical examination shows multiple pustules. Which of the following is the most appropriate next step?

O A) Ask the patient if he is concerned about the appearance of his skin O B) Obtain a dietary history O C) Suggest a new nonprescription medication O D) Provide a prescription for a topical antibiotic O E) Recommend a consultation with a dermatologist

44. A healthy 27-year-old woman comes to the physician for her first prenatal visit. She reports feeling tired but otherwise feels well. She has followed a strict vegetarian diet for 5 years. Laboratory studies show:

Hemoglobin 9.1 g/dLHematocrit 27%Leukocyte count 3200/mm3Platelet count 110,000/mm3

A Wright-stained peripheral blood smear is shown. The nutrient deficiency most likely responsible for her hematologic abnormalities significantly impairs which of the following cellular processes?

O A) Bilirubin conjugation O B) DNA synthesis O C) Fatty acid oxidation O D) Gluconeogenesis G E) Heme production

Lab Values F

45. A 27-year-old woman comes to the physician because of three episodes of right-sided abdominal pain during the past 2 weeks. She says that the pain is steady, radiates to the right shoulder, and lasts 60 to 90 minutes. She has had an intentional 18-kg (40-lb) weight loss during the past 10 weeks. She has not had fever or chills. Current medications include gemfibrozil for hypertriglyceridemia. She is 168 cm (5 ft 6 in) tall and weighs 93 kg (205 lb); BMI is 33 kg/m2. Abdominal examination shows mild right upper quadrant tenderness. Serum studies show an alkaline phosphatase activity of 85 U/L and amylase activity of 60 U/L. Which of the following is the most likely diagnosis?

O A) Acute pancreatitis O B) Cholelithiasis O C) Chronic pancreatitis O D) Crohn disease

46. A 54-year-old man is brought to the emergency department 15 minutes after the abrupt onset of crushing substernal chest pain. He appears in distress. His pulse is 98/min, respirations are 24/min, and blood pressure is 104/56 mm Hg. Cardiac examination shows an S3 gallop. An ECG shows a 6-mm anterior ST segment elevation and isolated premature ventricular contractions. Following placement of a coronary stent and restoration of blood flow, he develops an idioventricular rhythm. Which of the following is the most likely underlying cause of this abnormal rhythm?

O A) Activation of free radical scavenging systems O B) Decreased lipid peroxidation O C) Generation of reactive oxygen species O D) Inactivation of free radical scavenging systems O E) Increased calbindin concentration

47. A 26-year-old man who was stabbed in the right side of the neck has a nerve injury. The physician is unable to detect a muscle stretch reflex in the right biceps. This injury most likely affected the function of which of the following nerves?

O A) Axillary O B) Median O C) Musculocutaneous O D) Radial O E) Ulnar

48. A 6-year-old boy is brought to the physician by his mother for examination prior to attending camp. His mother says that he often complains that his feet are cold. He is at the 50th percentile for height and weight. His blood pressure is 170/110 mm Hg. Radial artery pulses are strong. Which of the following is the most likely diagnosis?

O A) Coarctation of the aorta O B) Cushing syndrome O C) Nephroblastoma (Wilms tumor)O D) Renovascular hypertension O E) Takayasu arteritis

49. A 60-year-old man is brought to the emergency department because of a severe headache and weakness on the left 3 hours after falling from a ladder and hitting his head on the sidewalk. He briefly lost consciousness but is awake on arrival at the emergency department. He is alert and oriented. His temperature is 36.1°C (97°F), pulse is 65/min, respirations are 12/min, and blood pressure is 160/100 mm Hg. Neurologic examination shows a dilated pupil on the right and a normal pupil on the left. He has mild weakness of his left upper and lower extremities. Which of the following findings is most likely on a CT scan of the head?

O A) Brain stem hemorrhage O B) Herniation of the cerebellar tonsils O C) Herniation of the cingulate gyrus O D) Herniation of the uncus O E) Subarachnoid hemorrhage

A *±B +C AG °= -11.1 kcal/mol

C+D E AG °= +6.4 kcal/mol

A + D ^E +B2

50. Two chemical reactions are shown schematically, each with its aG°. C represents the same compound in each reaction. For the reaction shown, which of the following sets of values is most likely correct for aG° and direction?

aG° DirectionO A) +17.5 1O B) +17.5 2O C) -4.7 1O D) -4.7 2O E) -17.5 1O F) -17.5 2