A 4-day-old male newborn delivered at 39 weeks' gestation is evaluated because of poor feeding, recurrent vomiting, and lethargy. Physical examination shows tachypnea with subcostal retractions. An enzyme assay performed on a liver biopsy specimen shows decreased activity of carbamoyl phosphate synthetase I. This enzyme plays an important role in the breakdown and excretion of amino groups that result from protein digestion. Which of the following is an immediate substrate for the synthesis of the molecule needed for the excretion of amino groups?
AN-acetylglutamate
BHomocysteine
CPhenylalanine
DValine
EAspartate
A 56-year-old woman with a history of alcoholic cirrhosis and recurrent esophageal varices who recently underwent transjugular intrahepatic portosystemic shunt (TIPS) placement is brought to the emergency room by her daughter due to confusion and agitation. Starting this morning, the patient has appeared sleepy, difficult to arouse, and slow to respond to questions. Her temperature is 97.6°F (36.4°C), blood pressure is 122/81 mmHg, pulse is 130/min, respirations are 22/min, and oxygen saturation is 98% on room air. She repeatedly falls asleep and is combative during the exam. Laboratory values are notable for a potassium of 3.0 mEq/L. The patient is given normal saline with potassium. Which of the following is the most appropriate treatment for this patient?
ARifaximin
BLactulose
CNadolol
DCiprofloxacin
EProtein-restricted diet
A 3-week old boy is brought to the physician for the evaluation of lethargy, recurrent vomiting, and poor weight gain since birth. Physical examination shows decreased skin turgor and a bulging frontal fontanelle. Serum studies show an ammonia concentration of 170 μmol/L (N < 30) and low serum citrulline levels. The oral intake of which of the following nutrients should be restricted in this patient?
AGluten
BLactose
CFructose
DProtein
EVitamin A
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