A 68-year-old man with type 2 diabetes mellitus comes to the physician because of a 5-month history of episodic palpitations, dizziness, and fatigue. His pulse is 134/min and irregularly irregular, and his blood pressure is 165/92 mm Hg. An ECG shows a narrow complex tachycardia with absent P waves. He is prescribed a drug that decreases the long-term risk of thromboembolic complications by inhibiting the extrinsic pathway of the coagulation cascade. The expected beneficial effect of this drug is most likely due to which of the following actions?
AInhibit the reduction of vitamin K
BActivate gamma-glutamyl carboxylase
CInhibit the phosphorylation of glutamate on the factor II precursor
DActivate factor VII calcium-binding sites
EInhibit the absorption of vitamin K
An investigator is studying nutritional deficiencies in humans. A group of healthy volunteers are started on a diet deficient in pantothenic acid. After 4 weeks, several of the volunteers develop irritability, abdominal cramps, and burning paresthesias of their feet. These symptoms are fully reversed after reintroduction of pantothenic acid to their diet. The function of which of the following enzymes was most likely impaired in the volunteers during the study?
AGamma-glutamyl carboxylase
BAlpha-ketoglutarate dehydrogenase
CDopamine beta-hydroxylase
DMethionine synthase
EGlutathione reductase
A 43-year-old woman visits her primary care provider complaining of fatigue. Although she has had it for several months, her fatigue has been worsening over the past few weeks. She has no other symptoms. Past medical history is significant for hypertension. She takes chlorthalidone, an oral contraceptive pill, and a multivitamin every day. Family history is noncontributory. She drinks about 1 bottle of wine every day and started taking a shot or two of whisky or vodka every morning before work to “clear out the cobwebs”. She was recently fired from her job. Today, her heart rate is 90/min, respiratory rate is 17/min, blood pressure is 110/65 mm Hg, and temperature is 36.7°C (98.1°F). On physical exam, she appears malnourished and anxious. Her conjunctiva are pale, and glossitis is noted on oral exam. Her heart has a regular rate and rhythm and her lungs are clear to auscultation bilaterally. She has no gait or balance abnormalities. Lab results show a hemoglobin of 10 g/dL, with a mean corpuscular volume (MCV) of 108 fl. Elevated level of which of the following will most likely to be found in this patient?
AMethionine
BPhenylalanine
CCysteine
DHomocysteine
EMethylmalonic acid
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