A 58-year-old man dies from heart failure that was refractory to therapy. At autopsy his heart weighs 490 g. Sections of his heart are shown. Which of the following is the most likely diagnosis?

A 58-year-old woman comes to the office because of a 1-month history of fatigue, fever, shortness of breath, and joint pain; she also has had a 3.2-kg (7-lb) weight loss during this period. Her temperature is 37.6°C (99.7°F), and respirations are 34/min. Physical examination shows tenderness to palpation over the maxillary sinus, nasal ulcerations, and a bulging, red left tympanic membrane. Laboratory studies show:

Histologic examination of a biopsy specimen of affected lung tissue shows granulomata and vasculitis. An autoantibody is most likely directly binding which of the following cell types in this patient?

A 38-year-old woman has had a slowly enlarging pink papule on her left cheek for 1 year. A photomicrograph of a biopsy specimen of the papule is shown. Which of the following is the most likely diagnosis?

A 47-year-old woman comes to the physician because of a 1-week history of yellow-tinged eyes and itchy skin. Physical examination shows scleral icterus and multiple excoriations over the trunk. Serum studies show:

This patient most likely has a deficiency of which of the following?

A 47-year-old woman comes to the physician because of a 1-week history of yellow eyes and itching skin. Physical examination shows scleral icterus and excoriations over the trunk. Serum studies show:

This patient most likely has a deficiency of which of the following vitamins?

A 25-year-old woman comes to the physician because of progressive fatigue during the past 5 months. She says that she falls asleep several times daily. She takes no medications. She is 152 cm (5 ft) tall and weighs 154 kg (340 lb); BMI is 66 kg/m2. Her blood pressure is 150/90 mm Hg. Physical examination shows no other abnormalities. Laboratory studies show:

The results of a urine drug screen are negative. Which of the following is the most likely cause of the somnolence in this patient?

A 26-year-old woman with mild intellectual developmental disorder is brought to the physician by her father because he is concerned about her recent disruptive behavior. The father often conducts business with clients at home, and the patient frequently interrupts his business meetings wearing revealing clothing. She has three sisters who are married, and she often states that she wants her own husband. The father asks the physician to prescribe enough medication for his daughter so that she no longer embarrasses him. Which of the following is the most appropriate initial action by the physician?

A 68-year-old man comes to the physician because of a 6-month history of progressive shortness of breath. He also has a 1-month history of nonproductive cough. He has a long history of joint pain treated with prednisone. He does not smoke cigarettes, but he was raised in a coal mining community. Vital signs are within normal limits. Physical examination shows no jugular venous distention or edema. There are small painless nodules along the extensor surface of both forearms, ulnar deviation, and swan neck deformities of the fingers. Bilateral diffuse crackles are heard on auscultation of the chest. A chest x-ray shows a diffuse fibronodular infiltrate with a right pleural effusion. A thoracentesis is done, and pleural fluid analysis shows straw-colored fluid containing 200 leukocytes/mm3 and a glucose concentration of 12 mg/dL (N=70). Which of the following is the most likely underlying cause of his current condition?

An 82-year-old woman is brought to the physician by her son because of a 1-year history of increasing word-finding difficulty and a 3-year history of increasing forgetfulness. She has hypertension and hypercholesterolemia. Her medications are lisinopril and atorvastatin. Her blood pressure is 120/80 mm Hg. Physical examination shows no abnormalities. On mental status examination, she is alert and attentive. She recalls one of five parts of a name and address after 5 minutes, and does not recognize the remaining parts when given clues for each. She recalls zero of three figures 5 minutes after copying them. She cannot name the point of a pen or the band of a watch. Degeneration of which of the following is the most likely cause of this patient’s memory changes?

A 53-year-old woman comes to the physician because of a 1-month history of persistent headaches. Physical examination shows no abnormalities. CT scans of the head are shown. Further studies confirm a tumor of the hypophysis. This patient is at greatest risk for compression of which of the following nerves?

A new rare genetic disease is caused by a mutation in the gene coding for cysteine-tRNA. This results in the substitution of tyrosine for cysteine. Which of the following is the most likely major effect of this amino acid substitution?

A 36-year-old man comes to the physician because of fever and frequent slimy stools for 2 weeks. He recently emigrated from Ecuador. His temperature is 38.2°C (100.8°F). Abdominal examination shows mild tenderness of the right upper quadrant. Examination of the stool shows mucus. Colonoscopy shows multiple flask-shaped ulcers that have undermined and destroyed large areas of the intestinal epithelium. Which of the following is the most likely causal organism?

During a study, an investigator sequences a mature mRNA isolated from a human cell line. Adenine is found to repeat 200 times at the 3′ end of mRNA. This polyadenylation will most likely have which of the following effects on the translation of mRNA?

An experiment is conducted to assess the adaptation of certain bacteria to hospital environments. The investigator identifies antibiotic resistance markers located on transposons that permit bacteria to adapt to these environments and perpetuate resistance. These transposons are observed to be mobile genetic elements that can incorporate into a chromosome without having DNA homology. Which of the following factors permits this genetic promiscuity?

A 27-year-old man comes to the physician because of a 3-week history of pain in his back and flanks. His blood pressure is 153/87 mm Hg. Palpation of the abdomen and flanks shows enlarged kidneys bilaterally. Renal ultrasound shows multiple cysts in the cortex and medulla of each kidney. Cysts are also likely to be found in which of the following organs?

A 23-year-old woman has a grade 3/6 systolic murmur. Cardiac catheterization shows:

Which of the following is the most likely diagnosis?

While being treated for urosepsis in the intensive care unit, a 69-year-old man develops bleeding from sites of intravenous catheterization. He is receiving cefepime, dopamine, and 0.9% saline. He is obtunded. His temperature is 38.2°C (100.8°F), pulse is 90/min, respirations are 30/min, and blood pressure is 90/60 mm Hg. Physical examination shows oral bleeding and oozing at intravenous catheter sites and previous puncture sites. Laboratory studies show:

Which of the following is the most likely diagnosis?

A 46-year-old man comes to the emergency department because of an 18-hour history of fever, nausea, vomiting, and severe pain of his middle and left upper abdomen that radiates to his back. He recently returned from a 3-day fishing trip with some friends; he drank six to eight beers daily during this period. He says that he has had similar symptoms after binge drinking in the past. He has hyperlipidemia treated with simvastatin. He appears diaphoretic. His temperature is 39.3°C (102.8°F). Abdominal examination shows mild distention and tenderness over the epigastric region and left upper quadrant. Laboratory studies show:

This patient most likely has which of the following underlying processes?

A study is conducted to assess the distribution of preoperative serum creatinine concentrations among a small group of patients who are scheduled to undergo operative procedures at a local hospital. Seven consecutive patients are enrolled. The results are shown:

During documentation of these measurements, the fourth datum point (0.9) is inadvertently recorded as 9. Which of the following measures will be most impacted by this error?

A study is conducted to assess the efficacy of bisphosphonate treatment in preventing vertebral fractures in women with low bone density. A total of 257 women with low bone density and no history of fractures are randomly assigned to receive a bisphosphonate or placebo for 3 years. Results show:

Based on these data, which of the following mathematical expressions should be used to calculate the number of women that must be treated with a bisphosphonate to prevent one fracture?

An 18-year-old woman comes to the physician because of a 3-week history of intermittent double vision and transient vision loss. She also has had a 9-kg (20-lb) weight loss during the past 5 months due to decreased appetite. She is 152 cm (5 ft) tall and now weighs 51 kg (112 lb); BMI is 22 kg/m2. Her temperature is 38°C (100.5°F), and blood pressure is 146/88 mm Hg. Funduscopic examination shows a recent retinal hemorrhage of the left eye. Cardiac examination shows bilateral carotid bruits. Radial pulses are diminished on the right side and absent on the left side. Laboratory studies show:

Histologic examination of a carotid artery in this patient will most likely show which of the following types of vasculitis?

A 56-year-old woman comes to the physician because of progressive shortness of breath and cough during the past 2 weeks. Her respirations are 20/min. Crackles are heard on auscultation. A chest x-ray shows bilateral pleural effusions. A thoracentesis is done. Pleural fluid analysis shows:

Which of the following is the most likely underlying cause of the findings in this patient?

Two randomized, double-blind studies (Study X and Study Y) are conducted to assess the efficacy of a new chemotherapeutic agent. For each study, patients are randomized to receive either placebo or the new experimental chemotherapy; all subjects are then followed for a mean of 5 years. Follow-up rates are 92% in Study X and 91% in Study Y. Results show:

The relative risk of dying of cancer is 0.7 in Study X (95% confidence interval of 0.2 to 2.4) and 0.6 in Study Y (95% confidence interval of 0.5 to 0.7). Which of the following best accounts for this difference in confidence intervals?

A previously healthy 4-year-old boy is brought to the physician because of a 1-week history of easy fatigability and swelling of his face and feet. His temperature is 37.1°C (98.8°F), pulse is 100/min, respirations are 20/min, and blood pressure is 85/67 mm Hg. Physical examination shows facial edema, abdominal distention, and a 3-cm umbilical hernia. There is 3+ pitting edema of the ankles and feet. Laboratory studies show:

One week later, the patient develops a temperature of 39°C (102.2°F), severe abdominal pain, and chills. Abdominal paracentesis yields turbid peritoneal fluid that grows Streptococcus pneumoniae. Further studies will most likely show a decrease in which of the following in this patient?

A 24-year-old primigravid woman at 36 weeks’ gestation comes to the physician because of a 3-day history of ankle swelling. She has gained 2.7 kg (6 lb) during the past week. She has no history of major medical illness, and her pregnancy has been uncomplicated. Her temperature is 37°C (98.6°F), pulse is 85/min, and blood pressure is 160/100 mm Hg. Physical examination shows a uterus consistent in size with a 36-week gestation. There is mild facial edema and pitting edema of the lower extremities and ankles bilaterally. Laboratory studies show:

Labor is induced, and the patient delivers a healthy male newborn. The placenta is removed and sent for analysis. Histologic examination of the placenta is most likely to show which of the following characteristics of this patient’s gestational disorder?

A 48-year-old woman comes to the emergency department 2 hours after the sudden onset of severe flank pain. She also has a 2-month history of mild exacerbation of her baseline constipation. She has had no fever, chills, pain with urination, or increased urinary frequency. She has a history of infrequent urinary tract infections, with the most recent occurring more than 5 years ago. She has no personal or family history of renal calculi. Her pulse is 92/min, and blood pressure is 138/88 mm Hg. Physical examination shows no other abnormalities. Laboratory studies show:

Which of the following is the most likely cause of these findings?

A 5-year-old girl with a history of recurrent infections since the age of 4 months is brought to the physician for a follow-up examination. She has had multiple episodes of pneumonia, sinusitis, otitis media, and diarrhea. She is at the 20th percentile for height and weight. Her temperature is 37.4°C (99.3°F). Mild crackles are heard bilaterally over the lower lung lobes. Laboratory studies show:

This patient most likely has an abnormality of which of the following immune system components?

A 68-year-old woman comes to the physician for a follow-up examination after a routine endoscopy for dyspepsia showed large esophageal varices. She has a 25-year history of type 2 diabetes mellitus. She also has hypertension and hyperlipidemia. She does not have any history of liver disease, blood transfusions, or intravenous drug use, and she does not drink alcohol. Her current medications are 81-mg aspirin, insulin, lisinopril, and simvastatin. She appears alert. She is 168 cm (5 ft 6 in) tall and weighs 110 kg (242 lb); BMI is 39 kg/m2. Physical examination shows scattered spider angiomata over the chest and upper extremities. Abdominal examination shows no ascites. The spleen tip is palpated 4 cm below the left costal margin. Laboratory studies show:

Ultrasonography shows coarsened liver echotexture with increased echogenicity. Which of the following is the most likely cause of the liver findings in this patient?

A 72-year-old woman with mild dementia is brought to the office because of a nosebleed for 2 hours. She has no history of previous bleeding problems. There is no family history of bleeding disorder. She lives in a dilapidated farmhouse infested by rodents and has extensive exposure to rat poisons. Her temperature is 37.1°C (98.7°F), pulse is 85/min, respirations are 14/min, and blood pressure is 142/92 mm Hg. Physical examination shows bleeding from the left nostril with no petechiae. Laboratory studies show:

Treatment with an infusion of fresh frozen plasma controls the hemorrhage. Which of the following structural modifications in plasma coagulation proteins is most likely absent in this patient?

A 65-year-old woman comes to the office for a follow-up examination. She has chronic kidney disease, hypertension, and type 2 diabetes mellitus. Current medications are lisinopril, atorvastatin, and sitagliptin. She does not smoke or drink alcoholic beverages. Vital signs are within normal limits. Physical examination shows decreased sensation to monofilament over the distal lower extremities. Results of laboratory studies are shown:

Which of the following is the most likely cause of the laboratory findings in this patient?

A study is conducted to assess the effectiveness of an intervention at decreasing the incidence of hypertension. Patients at risk for this disease are enrolled in the study and are assigned to either a group receiving the intervention or a group that does not receive intervention. The hypothesis states that the intervention decreases the annual incidence of hypertension. The table is a conceptual representation of the randomized clinical trial.

Which of the following labeled cells in the table represents a Type II error?