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CASE FILES: BIOCHEMISTRY
[16.2] Which of the following best describes the reason for the latency of ace-
tonitrile toxicity and why prompt treatment would have prevented this
child’s respiratory distress and death?
A. Acetonitrile crosses the mitochondrial membrane slowly.
B. Acetonitrile induces hemolysis by inhibiting glucose 6-phosphate
dehydrogenase.
C. Acetonitrile is only poorly absorbed by the intestinal system.
D. Complex IV of the electron transport system binds acetonitrile
weakly.
E. Cytochrome P450 enzymes oxidize acetonitrile and slowly release
cyanide.
[16.3] Inhibition of oxidative phosphorylation by cyanide ion leads to
increases in which of the following?
A. Gluconeogenesis to provide more glucose for metabolism
B. Transport of ADP into the mitochondria
C. Utilization of fatty acids substrates to augment glucose utilization
D. Utilization of ketone bodies for energy generation
E. Lactic acid in the blood causing acidosis
[16.4] Which of the following procedures best describes the emergency inter-
vention for cyanide poisoning?
A. Decrease the partial pressure of oxygen
B. Treatment with nitrites to convert hemoglobin to methemoglobin.
C. Treatment with thiosulfate to form thiocyanate
D. Use of Mucomyst (V-acetylcysteine) taken orally
An unskilled worker in a water garden/plant nursery was sent to sweep
up a spill of a white powder in the storage shed. Later he was found
with labored breathing and convulsions. On further examination, the
white powder was identified as rotenone.
[16.5] Respiratory distress is induced on rotenone exposure because it
inhibits the complex that catalyzes which of the following?
A. Electron transfer from NADH to coenzyme Q
B. Oxidation of coenzyme Q
C. Reduction of cytochrome c
D. Electron transfer from cytochrome c to cytochrome a1/a3
E. Electron transfer from cytochrome a1/a3 to oxygen
[16.6] The major metabolic consequence of perturbation of the electron trans-
fer in mitochondria is which of the following?
A. Increased production of NADPH
B. Increased oxidation of NADH
C. Increased reduction of O2 to H2O
D. Decreased regeneration of NAD+
E. Decreased reduction of FAD
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