A newborn infant is resuscitated and transferred to the neonatal intensive care unit. The infant has notable limb deformities as well as low-set ears and a flattened nose. He was born at 34 weeks gestation to a healthy mother who received regular obstetric follow-up. Resuscitation was notable for difficulty maintaining oxygenation in the newborn. Despite appropriate interventions, the infant is still struggling to maintain adequate oxygenation. Which of the following is most likely the cause of this patient's symptoms?
APKD1 gene mutation
BCystic dilation of the collecting ducts in the kidney
CChromosomal abnormality
DMaternal diabetes
EFailure to administer betamethasone
An 18-month-old boy is brought to the physician because of a 2-day history of cough, fever, and lethargy. He has been admitted to the hospital twice during the past year for pneumonia. He can stand without support but has not started to walk. He speaks in bisyllables. He is at the 3rd percentile for height and 4th percentile for weight. Examination shows diffuse crackles over bilateral lung fields. Abdominal examination shows hepatosplenomegaly. Fundoscopy shows bright red macular spots. Despite being given appropriate antibiotic therapy, the patient dies. A photomicrograph of a section of the spleen obtained during autopsy is shown. Accumulation of which of the following substances is the most likely cause of this patient's condition?
ACeramide trihexoside
BCerebroside sulfate
CGlucocerebroside
DSphingomyelin
ELimit dextrin
A 61-year-old woman comes to the physician because of a 6-month history of left knee pain and stiffness. Examination of the left knee shows tenderness to palpation along the joint line; there is crepitus with full flexion and extension. An x-ray of the knee shows osteophytes with joint-space narrowing. Arthrocentesis of the knee joint yields clear fluid with a leukocyte count of 120/mm3. Treatment with ibuprofen during the next week significantly improves her condition. The beneficial effect of this drug is most likely due to inhibition of which of the following?
AConversion of hypoxanthine to urate
BConversion of phospholipids to arachidonic acid
CConversion of prostaglandin H2 to thromboxane A2
DConversion of arachidonic acid to prostaglandin G2
EConversion of dihydroorotate to orotate
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