CLINICAL CASES
289
resulting from prolonged exposure of bile acids to intestinal bacteria may
result in high levels of cholesterol in bile. In addition to elevated cholesterol
levels in bile, there must be adequate time for cholesterol crystal nucleation,
which will ultimately form macroliths. Fasting, like overnight sleeping, allows
for long-term storage of bile in the gallbladder and could give ample time for
crystal nucleation.
C O M P R E H E N SIO N Q U E ST IO N S
[31.1] The modification to bile salts that increases the working pH range and
amphipathic nature of bile salts is
A. 7a-Hydroxylation
B. Dehydroxylation by intestinal bacteria
C. Esterification
D. Conjugation to taurine or glycine
[31.2] A new drug called CT2033, a corticosteroid, has reached the clinical
trial stage. This drug was designed to treat inflammation but seems to
also cause an undesired side effect where there is disturbance of cho-
lesterol and bile acid homeostasis. Which of the following is
least
likely
to explain the side effects caused by CT2033?
A. It downregulates the expression of a hepatobiliary bile acid trans-
porter gene.
B. It inhibits a hepatobiliary transporter protein decreasing bile acid
secretion.
C. It competes with cholesterol for
CYP7A1
binding.
D. It binds and inhibits pancreatic lipases.
[31.3] A 53-year-old male patient with elevated levels of low-density lipopro-
tein (LDL) cholesterol, signs of premature cholesterol gallstone dis-
ease and substantially elevated triglycerides visited his physician for a
follow-up to check his current status. The patient had received various
statin, HMG-CoA-reductase inhibitors therapies for the past 2 years.
However, after blood work done at this follow-up visit, complications
had still not subsided. This patient has similar problems as two of his sib-
lings. Which of the following best explains this patients dyslipidemia?
A. An influx of abnormal phospholipids in the gallbladder as a result
of ileal disease
B. A loss of HMG-CoA reductase function
C. A loss of
CYP7A1
(cholesterol 7a-hydroxylase) function
D. Elevated levels of ACAT
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