A 31-year-old man comes to the physician 1 day after he noticed that the right side of his face was lower than the left while shaving. On physical examination, he is unable to grimace his right cheek or elevate his right eyebrow. Neurologic examination shows impaired facial expression and loss of taste in the anterior two thirds of the tongue. Which of the following additional neurologic findings is most likely in this patient?

A 3-year-old boy is brought to the physician because of a 6-month history of a sway back when standing. His brother had a history of muscle weakness and died of pneumonia at the age of 12 years. Physical examination shows hip girdle weakness. His serum creatine kinase concentration is markedly increased. This patient’s symptoms are most likely caused by the accumulation of a defective protein in which of the following locations in muscle cells?

A previously healthy 50-year-old man is brought to the physician because of a 2-week history of blurred vision. Neurologic examination shows inability of the left eye to look to the left. The right eye movement shows no abnormalities. This patient most likely has a lesion in which of the following labeled cranial nerves in the photograph of the brain stem shown?

A 55-year-old man comes to the office because of a 2-week history of an increasingly large and painful lump on his right shoulder. The lump began as a pea-sized red bump. He has no history of serious illness and takes no medications. Temperature is 38.0°C (100.4°F); all other vital signs are within normal limits. Physical examination shows a 5-cm, inflamed carbuncle on the right shoulder. Treatment with a 7-day course of cephalexin is initiated. The carbuncle in this patient is most likely located in the layer of skin that has which of the following embryologic precursors?

A 55-year-old man with a 10-day history of a blistering rash on his back comes to the physician for a follow-up examination. He completed a course of antiviral medication 3 days ago, and he continues to have moderate pain. His vital signs are within normal limits. Physical examination shows the findings in the photograph. This rash is most likely located in which of the following dermatomes?

An 8-year-old boy is brought to the physician because of an itchy rash for 3 days. Physical examination shows an excoriated rash over the right wrist and around the waist. A 1.5-cm linear tunnel is seen over the right wrist. A photomicrograph of scrapings from the affected area is shown. Which of the following is the most likely causal organism?

A 32-year-old woman comes to the physician because of a 6-week history of pain at the base of her right thumb. She does not recall any trauma but says that she typically carries her heavy 6-month-old son with her right arm. Her vital signs are within normal limits. A test involving flexion of the fingers over the thumb to make a fist, followed by ulnar deviation, is positive on the right. Which of the following is the most likely cause of this patient’s pain?

A 35-year-old man comes to the office because of a 3-month history of an enlarging, painless lump on the back of his left thigh. He also has had weakness in his left thigh and leg. Physical examination shows a 7-cm, hard, nonmobile swelling on the left posterior thigh. Sensation to pinprick is decreased along the posterior thigh and below the knee. Sagittal and axial views from a CT scan of the left thigh are shown. A biopsy specimen of the lump confirms a rhabdomyosarcoma. The most likely cause of the findings in this patient is compression of which of the following nerves?

A 9-year-old boy is brought to the physician by his mother 1 day after he had severe leg cramps while playing soccer. The mother says that he also has a 2-month history of fatigue and clumsiness, and that his face lacks expression. He tires easily with exercise. He has a 3-year history of migraine. He is at the 60th percentile for height and weight. Vital signs are within normal limits. Physical examination shows bilateral ptosis and limited vertical and horizontal gaze. His speech is slightly slurred. Examination of a muscle biopsy specimen shows ragged red fibers. Which of the following is the most likely diagnosis?

During a study of exercise physiology, a healthy 30-year-old woman runs on a treadmill for 20 minutes at a rate of 7 miles per hour. At the end of the study, her cardiac output has increased from 5 L/min to 15 L/min; the cerebral perfusion pressure has remained relatively constant. Which of the following mechanisms best explains these findings?

An 84-year-old man is brought to the emergency department 30 minutes after an episode of syncope. Transthoracic echocardiography shows a 4-cm myxoma occupying the majority of the left atrium. The tumor will be excised using a robotically assisted operation via an oblique right atriotomy and transection of the interatrial septum. When making the incision into the left atrium to remove the myxoma, which of the following regions of the interatrial septum should be avoided in order to prevent injury to the cardiac conduction system?

A 76-year-old man who has had no medical care for more than 10 years comes to the physician because of a 3-week history of intermittent episodes of dizziness and feeling faint. He says the symptoms are worse when he rises after lying down. He is unable to be even moderately physically active because of the dizziness. He has had no chest pain or shortness of breath during this period. His pulse is 30/min, respirations are 15/min, and supine blood pressure is 100/40 mm Hg. Physical examination shows no other abnormalities. An ECG is shown. This patient most likely has which of the following dysrhythmias?

A 22-year-old man comes to the office because of a 3-month history of episodes of severe abdominal pain with nausea and vomiting. Abdominal examination shows epigastric tenderness to palpation without rebound tenderness or guarding. Serum studies show a triglyceride concentration of 2000 mg/dL, amylase activity of 2000 U/L, and lipase activity of 1800 U/L. Abdominal ultrasonography shows no evidence of biliary tract obstruction. A drug from which of the following classes is most appropriate to treat this patient’s lipid abnormality?

A 42-year-old woman comes to the physician because of a 6-month history of progressive loss of peripheral vision. Ophthalmologic examination shows bitemporal hemianopia with normal fundi and visual acuity. A sagittal T1-weighted MRI of the brain with contrast is shown; the arrow indicates an abnormality. To surgically access and resect the mass via a nasal approach, which of the following sinuses must be traversed?

A 65-year-old man with chronic obstructive pulmonary disease comes to the office because of a 2-week history of progressive shortness of breath. He had smoked 1 pack of cigarettes daily for 40 years before quitting 1 year ago. Current medications include albuterol as needed. His respirations are 18/min. Physical examination shows wheezing. Pulmonary function testing shows an FEV1 that is 55% of predicted value compared with 65% 1 year ago. It is most appropriate to add a drug to this patient’s medication regimen that binds to or interferes with which of the following?

A 67-year-old man who is a retired coal miner comes to the physician because of a 2-year history of progressive shortness of breath. He also has had a 23-kg (50-lb) weight loss during this period. He appears cachectic. He is 175 cm (5 ft 9 in) tall and now weighs 54 kg (120 lb); BMI is 18 kg/m2. His temperature is 36.8°C (98.2°F), pulse is 100/min, respirations are 22/min, and blood pressure is 137/83 mm Hg. Physical examination shows symmetric air entry with no crackles or wheezes. A chest x-ray and photomicrograph of lung tissue obtained on biopsy are shown. The structure indicated by the arrow in the photomicrograph most likely represents which of the following?

A 40-year-old woman with primary pulmonary hypertension comes to the physician for a follow-up examination. Her blood pressure is 190/100 mm Hg. Echocardiography shows a peak pulmonary systolic pressure of 65 mm Hg. Treatment with bosentan is started. This therapy is most likely to result in blockade of the action of which of the following peptides in this patient?

A previously healthy 59-year-old man comes to the emergency department because of a 1-day history of fever, shortness of breath, and productive cough. He appears to be in moderate distress. His temperature is 38.4°C (101.1°F), and respirations are 26/min. Pulse oximetry on room air shows an oxygen saturation of 88%. Bronchial breath sounds are heard over the right lung base posteriorly with egophony and increased tactile fremitus. A chest x-ray shows right lower lobe pneumonia. Which of the following mechanisms is the most likely cause of the hypoxia in this patient?

A 27-year-old man is brought to the emergency department because of increasingly severe left-sided chest pain during the past 12 hours. The pain worsens on deep inspiration. He was moving furniture when the pain began. His father died of a myocardial infarction at the age of 58 years. His respirations are 18/min. Palpation over the costochondral junction to the left of the sternum reproduces the pain. Cardiac examination shows no abnormalities. Which of the following is the most likely diagnosis?

A 35-year-old woman comes to the physician because of a 2-week history of fatigue. Six months ago, she visited family in Brazil, where she was exposed to domestic and farm animals. Physical examination shows no abnormalities except for pallor. Laboratory studies show a hemoglobin concentration of 7.2 g/dL and a hematocrit of 23%. Which of the following is the most likely causal organism?

A 61-year-old man comes to the physician because of a 3-week history of progressive loss of appetite and difficulty swallowing. His last medical examination was 10 years ago. He has taken calcium carbonate for chronic heartburn and nonsteroidal anti-inflammatory drugs (NSAIDs) for joint aches for the past 10 years. He drinks approximately four to five 12-ounce beers daily. His diet consists primarily of meat and simple carbohydrates. He appears cachectic. Physical examination shows no other abnormalities. Esophagogastroduodenoscopy shows a stricture at the esophagogastric junction. Examination of a biopsy specimen of the esophagus shows adenocarcinoma. Which of the following is the strongest predisposing risk factor for this patient’s condition?

A 57-year-old woman with a history of gastroesophageal reflux disease undergoes upper endoscopy. Results show a 4-cm, bulging nodule in the stomach covered with an intact mucosal surface. The mass is subsequently resected, and examination shows that it is contained within the submucosa; it is fleshy and well circumscribed with minimal mucosal alterations. A diagnosis of gastrointestinal stromal tumor is made. Further examination of this tumor is most likely to show which of the following molecular alterations?

A 42-year-old man with a history of duodenal peptic ulcer disease has the sudden onset of severe epigastric and right upper quadrant abdominal pain. The abdomen is rigid, tightly distended, and hyperresonant. An x-ray of the abdomen shows air under both sides of the diaphragm. Which of the following structures is most likely involved with the patient’s ulcer?

A 52-year-old man comes to the physician because of vomiting for 24 hours. He has a 1-week history of chronic constipation with bloating and abdominal pain. He is 183 cm (6 ft) tall and weighs 111 kg (245 lb); BMI is 33 kg/m2. Abdominal examination of the left lower quadrant shows muscle guarding; palpation of this area produces pain. A CT scan of the abdomen shows diverticula. The diverticula are most likely present in which of the following regions of the gastrointestinal system in this patient?

A previously healthy 48-year-old woman comes to the emergency department because of a 4-hour history of constant abdominal pain and fever. The pain radiates to the right shoulder and is accompanied by nausea and vomiting with no blood. She takes no medications. She does not smoke cigarettes or drink alcohol. She is in acute distress. Her temperature is 38.2°C (100.8°F), pulse is 104/min, respirations are 22/min, and blood pressure is 142/86 mm Hg. Abdominal examination shows marked tenderness of the right upper quadrant with voluntary guarding. Bowel sounds are decreased. Which of the following responses is expected in this patient on palpation of the right upper quadrant of the abdomen during the respiratory cycle?

A 25-year-old man is brought to the emergency department by ambulance 2 hours after the sudden onset of severe midepigastric abdominal pain. He vomited a small amount of bloody fluid shortly after the pain began. En route, his pulse is 150/min, and blood pressure is 80/40 mm Hg. Perforation of the duodenum is suspected. Which of the following sets of abdominal physical findings is most consistent with this diagnosis?

A 31-year-old man is admitted to the hospital because of flank and abdominal pain. A CT scan of the abdomen shows an aneurysm of the proximal portion of the superior mesenteric artery. This aneurysm is most likely to compress and impede venous blood flow from which of the following organs?

During an experiment, a drug that specifically dilates the efferent arterioles of the kidney is infused into an experimental animal. Which of the following sets of renal changes is most likely to occur in response to the drug?

A 62-year-old man is admitted to the intensive care unit after having a myocardial infarction. During the next 36 hours, his serum creatinine concentration increases to 3.9 mg/dL and his urine output decreases. Three days later, he develops polyuria. At the time of discharge from the hospital, his serum creatinine concentration is 2.6 mg/dL. Which of the following is the most likely cause of this patient’s episode of acute kidney injury?

A 33-year-old woman comes to the emergency department because of a 4-day history of progressive shortness of breath that is worse at night. Five days ago, she had an uncomplicated vaginal delivery of a female newborn at term. Her respirations are 22/min. Bilateral crackles are heard on auscultation of the chest. Cardiac examination shows the point of maximal impulse to be displaced laterally and an S3 gallop. An ECG shows sinus tachycardia and nonspecific ST-T segment and T-wave changes. Echocardiography shows a left ventricular ejection fraction of 30%, global hypokinesis, and mild mitral regurgitation. Which of the following is the most likely diagnosis?

A 27-year-old woman who has had type 1 diabetes mellitus for 10 years delivers a plethoric, large newborn weighing 5 kg (11 lb). Eighteen hours after delivery, the newborn develops hypoglycemia. Which of the following is the best explanation for the hypoglycemia?

A 29-year-old woman with type 1 diabetes mellitus gives birth at home to a male newborn at 30 weeks’ gestation. During transport to the hospital, the newborn develops respiratory distress. The lower ribs and sternum retract on inspiration, and an expiratory grunt is audible. An x-ray of the chest shows uniform reticulogranular densities in both lung fields. Arterial Po2 is 60 mm Hg. Blood and sputum cultures are negative. Which of the following is the most likely cause of the hypoxemia in this newborn?

A 24-year-old woman has the onset of fever, chills, and lower abdominal pain on the second day of her menstrual period. Examination shows tenderness localized to the fallopian tubes and ovaries. A complete blood count shows leukocytosis. Which of the following is the most likely causal organism?

A 31-year-old man comes to the physician because of a 4-day history of vague lower abdominal discomfort. He has been treated with chemotherapy for the last 4 months for testicular embryonal carcinoma. His serum α-fetoprotein concentration, which was initially markedly increased, is now zero. Imaging studies show a persistent 6-cm, well-circumscribed, retroperitoneal mass. The mass is resected and a representative section is shown. Which of the following is the most likely diagnosis?

A 29-year-old man comes to the physician with his 27-year-old wife because they have been unable to conceive for 1 year. Previous examination of the wife showed no abnormalities. Physical examination shows normal genitalia. His serum testosterone and luteinizing hormone concentrations are within the reference ranges and serum follicle-stimulating hormone concentration is increased. Semen analysis shows decreased sperm count. A decreased serum concentration of which of following is the most likely in this patient?

30-year-old woman comes to the physician because of a 3-week history of palpitations; she also has had a 4.5-kg (10-lb) weight loss during this period. Her pulse is 110/min. Physical examination shows a goiter and a fine resting tremor. Serum studies show a thyroid-stimulating hormone concentration of <0.1 μU/mL and thyroxine (T4 ) concentration of 50 μg/dL. A thyroidal iodine (123 I) uptake scan is shown. Which of the following structures is identified by the arrow in this image?

An 18-year-old woman with a 3-year history of type 1 diabetes mellitus is brought to the emergency department because of a 2-day history of light-headedness and urinary frequency with a large volume of urine. She has had nausea and has not eaten or taken her insulin for the past 2 days. She appears tired. Her pulse is 110/min, respirations are 22/min, and blood pressure is 98/68 mm Hg. Physical examination shows dry mucous membranes and decreased skin turgor. Her breath has a fruity aroma. Which of the following mechanisms is most likely occurring in this patient?

An 18-year-old woman with a 3-year history of type 1 diabetes mellitus is brought to the emergency department because of a 2-day history of light-headedness and urinary frequency with a large volume of urine. She has had nausea and has not eaten or taken her insulin for the past 2 days. She appears tired. Her pulse is 110/min, respirations are 22/min, and blood pressure is 98/68 mm Hg. Physical examination shows dry mucous membranes and decreased skin turgor. Her breath has a fruity aroma. Which of the following mechanisms is most likely occurring in this patient?

A 40-year-old woman comes to the physician because of episodes of fainting during the past 2 weeks. She also has a 3-month history of easy fatigability, irritability, headaches on awakening, and extreme hunger. Physical examination shows no abnormalities. Her serum glucose concentration is 35 mg/dL. A CT scan of the abdomen shows a mass in the pancreas. Immunohistochemical labeling of neoplastic cells obtained on biopsy of the mass is most likely to involve the use of antibodies directed to which of the following pancreatic secretory products?

A 68-year-old woman has been hospitalized for 2 weeks because of severe pneumonia complicated by septicemia and respiratory failure. She has a long-standing history of type 2 diabetes mellitus and a family history of chronic autoimmune (Hashimoto) thyroiditis. Her serum triiodothyronine (T3 ) and thyroxine (T4 ) concentrations are below the reference ranges, and serum thyroid-stimulating hormone and free T4 concentrations are within the reference ranges. Which of the following best explains these findings?

A 65-year-old woman comes to the office because of a 6-week history of a rash on her face and hands; the rash is exacerbated by sun exposure. She also has had difficulty climbing stairs and holding her arms above her head, such as when combing her hair. Examination of the hands shows the findings in the photograph. This patient most likely has which of the following underlying conditions?

A 45-year-old man is brought to the emergency department because of a 45-minute history of abdominal pain, diaphoresis, and weakness. Two hours ago, he spilled a chemical on his left arm while mixing the solution for crop dusting. His respirations are 8/min, and blood pressure is 100/55 mm Hg. Physical examination shows salivation, wheezing, diaphoresis, and muscle weakness. After confirming the identity of the solution, the physician begins treatment with atropine and pralidoxime. The chemical solution most likely contained which of the following?

Public health officials in a large metropolitan city in the US would like to decrease the prevalence of obesity in the city’s population. A tax on carbonated and other sugar-based beverages is subsequently implemented. Which of the following best describes this type of intervention?

A study of 10 patients with severe emphysema who were treated with oral theophylline for 12 weeks found no improvement in the exercise ability of these patients after treatment. Which of the following best describes this study design?

A study is done to determine the relationship between use of oral contraceptives and cervical cancer. Study subjects include 50,000 women who are using oral contraceptives and 50,000 women who have had a tubal ligation. After 2 years of follow-up, the rate of in situ cervical cancer is 18 per 10,000 women among users of oral contraceptives and 3 per 10,000 among sterilized women (p<0.05). Which of the following is the design of this study?

A 35-year-old man is brought to the emergency department 30 minutes after fainting while at work. He is conscious and is able to state his name and what he was doing before the episode. He says that he has had fatigue during the past 3 weeks. He has no history of major medical illness and takes no medications. His mother died of ovarian cancer at the age of 40 years. His maternal grandfather died of colon cancer at the age of 49 years. The patient does not smoke or drink alcoholic beverages. He appears pale. His temperature is 37.5°C (99.5°F), pulse is 110/min, respirations are 20/min, and blood pressure is 95/55 mm Hg. Physical examination shows no other abnormalities. Laboratory studies show a hemoglobin concentration of 6.2 g/dL and hematocrit of 19%. Test of the stool for occult blood is positive. Colonoscopy shows an isolated right-sided mass. Examination of a biopsy specimen of the mass shows a poorly-differentiated adenocarcinoma with mucinous features. Immunohistochemistry of the biopsy specimen is most likely to show loss of expression of which of the following proteins?