A 52-year-old woman comes to the office due to 2 weeks of constant back pain.  She has also had several months of nonproductive cough, anorexia, and unintentional weight loss.  The patient has a 40-pack-year smoking history.  Physical examination shows diffuse muscle wasting, left lung crackles, and vertebral tenderness.  Imaging reveals a left lung mass and lytic lesions in the vertebrae.  Further evaluation confirms metastatic non-small cell lung cancer.  Treatment with a cisplatin-based chemotherapy is begun, and the patient is also started on a neurokinin-1 receptor antagonist.  The latter medication is most likely to improve which of the following in this patient?

A 58-year-old man comes to the emergency department due to wound dehiscence.  The patient had a left subclavian catheter port placed 3 months ago to begin bevacizumab infusions for recurrent glioblastoma.  The incision wound closed completely but has now partially reopened.  Vital signs are normal.  Examination of the left side of the chest reveals that 50% of the incision has opened; subcutaneous tissue and part of the port are visible, but there is no drainage from the wound or erythema of the surrounding skin.  A complication of bevacizumab is suspected.  Which of the following is the most likely primary mechanism of this patient’s wound dehiscence?

A clinical trial is conducted to assess the effectiveness of a novel formulation of cisplatin for treating advanced non–small cell lung cancer.  Study participants are randomly assigned to 2 different cisplatin-based chemotherapy regimens.  Subjects in the control arm are administered conventional cisplatin chemotherapy, whereas those in the experimental arm are given a formulation of cisplatin encapsulated in liposomes coated with anti–epidermal growth factor receptor (EGFR) antibodies.  Patients in the experimental group are found to have a statistically significant decrease in residual tumor burden compared with those in the control group.  The incidence of adverse effects was also lower in the experimental group.  Compared to conventional cisplatin chemotherapy, the new formulation is most likely to have which of the following effects?

A 56-year-old man comes to the emergency department due to right lower extremity pain and swelling.  The symptoms began shortly after he flew back to the United States from a 7-day cruise in Indonesia.  Doppler ultrasonography reveals a femoropopliteal venous thrombosis, and the patient is given anticoagulation with rivaroxaban.  Compared to vitamin K antagonists, this patient’s treatment is most likely to have which of the following benefits?

A 64-year-old man comes to the office for follow-up.  He has a history of chronic kidney disease due to hypertensive and diabetic nephropathy.  Six months ago, he developed significant fatigue and exercise intolerance.  Evaluation at that time revealed normocytic anemia and normal serum iron studies so recombinant erythropoietin was initiated.  Today, the patient states that his symptoms have significantly improved.  Laboratory evaluation reveals a hemoglobin of 12 g/dL.  If the erythropoietin treatment is continued, this patient is at greatest risk for which of the following complications?

A 36-year-old woman with mitral valve prolapse comes to the office due to dyspnea and is found to have severe mitral valve regurgitation.  Two weeks later, the patient undergoes elective mechanical mitral valve replacement.  Continuous heparin infusion and oral warfarin are initiated following the procedure.  Coagulation studies during admission are as follows:

The patient achieves the goal of INR ≥2.5 on postoperative day 5 and heparin infusion is discontinued.  Which of the following likely caused the delay in achieving therapeutic INR in this patient?

A 26-year-old woman comes to the emergency department for pelvic pain and vaginal bleeding over the past 2 days.  Today, the pain has increased, but she has had no nausea, vomiting, or orthostasis.  The patient was treated for chlamydia cervicitis 3 years ago.  She takes no medications and has no known drug allergies.  On pelvic examination, the uterus is small and mobile and there is left adnexal tenderness.  Pelvic ultrasound reveals a complex, 2-cm left adnexal mass with a gestational sac and yolk sac; there is no intrauterine pregnancy or free fluid.  The patient is counseled on recommended medical treatment.  Which of the following is the mechanism of action of the agent of choice for this patient?

A 78-year-old man is found unresponsive and is brought by ambulance to the emergency department.  Upon arrival, the family says he has a complicated medical history and takes multiple medications but has no known drug allergies.  Noncontrast CT scan of the head reveals intracranial hemorrhage.  The patient is given a recombinant biologic agent that has antigen homology with factor Xa but no catalytic effect.  The agent is most likely to antagonize the effects of which of the following drugs?

A 65-year-old man is brought to the emergency department after developing sudden-onset right-side weakness and difficulty speaking.  He has a history of paroxysmal atrial fibrillation and has been taking warfarin for the past several years with a stable prothrombin time.  His wife adds that he started taking a new drug 2 weeks ago, but she does not remember its name.  Physical examination shows right hemiplegia, right hemisensory loss, expressive aphasia, and right homonymous hemianopia.  MRI of the head shows a left middle cerebral artery territory infarct.  Transesophageal echocardiogram reveals a small thrombus in the left atrium.  This patient most likely started taking which of the following drugs recently?

A 45-year-old-woman comes to the office for follow-up 2 weeks after hospitalization for acute pyelonephritis.  The patient was treated with morphine for pain and a course of broad-spectrum antibiotics, which she has completed.  Her symptoms have now resolved.  The patient also has a history of mechanical mitral valve replacement and takes warfarin.  Physical examination shows no new findings.  Her INR was 2.5 at the time of hospital discharge but is 6.2 today despite no change to warfarin dosage.  Which of the following best explains the laboratory findings in this patient?

A 64-year-old man comes to the office due to several weeks of worsening back pain, fatigue, and polyuria.  Physical examination reveals mucosal pallor and diffuse bony tenderness.  Laboratory studies are significant for normocytic anemia, hypercalcemia, and renal failure.  Serum protein electrophoresis demonstrates a monoclonal spike in the gamma globulin region.  Bone marrow biopsy shows a large number of abnormal plasma cells.  Treatment with lenalidomide is started; this medication increases affinity of E3 ubiquitin ligase enzyme to substrate transcription factors.  Which of the following is the most likely effect of this medication on these transcription factors?

A 9-year-old boy with a history of sickle cell disease is brought to the office due to fatigue.  The patient takes penicillin, hydroxyurea, and folic acid daily.  Temperature is 37.1 C (98.8 F), blood pressure is 102/68 mm Hg, pulse is 130/min, and respirations are 20/min.  Examination shows conjunctival pallor.  The oropharynx is clear and the neck is supple.  The lungs are clear to auscultation bilaterally, and the abdomen is soft with normal bowel sounds; there is no organomegaly.  Skin examination is unremarkable.  Laboratory results are as follows:

Which of the following is the most likely cause of this patient’s findings?

A 32-year-old woman, gravida 2 para 1, has a spontaneous vaginal delivery.  Immediately after delivery of the placenta, the patient has a large amount of vaginal bleeding with passage of fist-sized clots, findings consistent with postpartum hemorrhage.  A dose of tranexamic acid is administered.  Which of the following is the most likely mechanism of action of this drug?

A 66-year-old woman is brought to the emergency department due to left leg pain.  Five days ago, the patient underwent elective right hip arthroplasty for advanced osteoarthritis.  She had been recovering well at an acute rehabilitation facility until she woke today with severe left calf pain and swelling.  The patient has taken daily subcutaneous, low-molecular-weight heparin and as-needed acetaminophen since the surgery.  She has no other medical conditions.  Temperature is 37 C (98.6 F), blood pressure is 130/70 mm Hg, and pulse is 92/min.  The surgical incision over her right hip is healing well.  Her left posterior calf is tender and swollen to the knee.  Three days ago, complete blood count was normal, but platelet count is now 70,000/mm³.  Peripheral blood smear shows decreased platelet number but no other abnormalities.  Which of the following is the most likely cause of this patient’s thrombocytopenia?

A 35-year-old, previously healthy man is evaluated immediately after accidental exposure to ionizing radiation at a fluoroscopy manufacturing facility.  The patient is currently asymptomatic.  Vital signs are normal.  Physical examination shows no abnormalities.  If radiation exposure is significant, which of the following cells are most likely to be affected first?

Researchers are studying various cellular processes in normal and diseased states to find new anticancer drug targets.  They develop a medication that inhibits an intracellular enzyme that converts adenosine to inosine.  With drug use, accumulation of enzyme substrates in the neoplastic cells leads to DNA strand breaks and subsequent apoptosis.  Which of the following malignancies is likely to be most responsive to this medication?

A 34-year-old man comes to the office due to severe fatigue.  The patient was diagnosed with paroxysmal nocturnal hemoglobinuria 3 years ago, and he has required several blood transfusions due to anemia.  Treatment is initiated with a monoclonal antibody that prevents formation of the protein complex leading to hemolysis in this patient.  Prophylactic pharmacotherapy will be required to prevent infection by which of the following organisms?

A 57-year-old woman comes to the emergency department due to cough and hemoptysis.  The patient also reports several months of fatigue and joint pain.  Physical examination is notable for crusting of the nasal mucosa, lung crackles, and scattered palpable purpura over the lower extremities.  Chest x-ray reveals bilateral, diffuse alveolar infiltrates.  Laboratory studies show normocytic anemia, red blood cell casts and protein in the urine, and positive c-ANCA.  After a confirmatory biopsy, treatment with rituximab infusion is planned.  This medication is most likely to improve this patient’s condition via which of the following mechanisms?

A 5-year-old boy is admitted to the hospital after being diagnosed with B-cell acute lymphoblastic leukemia.  Treatment is being discussed with the family, including regimens with various standard chemotherapeutic drugs such as vincristine, prednisone, asparaginase, methotrexate, cyclophosphamide, and mercaptopurine.  One of the consequences of treatment with the proposed options is the risk of developing a secondary malignancy.  Which of the following agents confers the greatest risk for this adverse effect?