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    BioPatel is offline Member
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    A 47-year-old male patient presents with painful arthritis

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    A 47-year-old male patient presents with A 47-year-old male patient presents with painful arthritis in the right big toe and uric acid renal stones. He has been taking allopurinol for his condition. What biochemical defect would likely be found in this patient?

    A. A defect in urea synthesis
    B. An abnormality of the purine degradation pathway
    C. An inability to synthesize non-essential amino acids
    D. Defective topoisomerases
    E. Increased levels of leukotrienes

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    Re: A 47-year-old male patient presents with painful arthritis

    Quote Originally Posted by BioPatel
    A 47-year-old male patient presents with A 47-year-old male patient presents with painful arthritis in the right big toe and uric acid renal stones. He has been taking allopurinol for his condition. What biochemical defect would likely be found in this patient? A. A defect in urea synthesis
    B. An abnormality of the purine degradation pathway
    C. An inability to synthesize non-essential amino acids
    D. Defective topoisomerases
    E. Increased levels of leukotrienes
    . He has been taking allopurinol for his condition. What biochemical defect would likely be found in this patient?

    A. A defect in urea synthesis
    B. An abnormality of the purine degradation pathway
    C. An inability to synthesize non-essential amino acids
    D. Defective topoisomerases
    E. Increased levels of leukotrienes
    [/i]

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    B.

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    Asclepius1's Avatar
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    This guy has Leschyn

  5. #5
    BioPatel is offline Member
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    The correct answer is B. This patient has gout, characterized by painful joints due to the precipitation of uric acid crystals caused by excessive production of uric acid (a minority of cases are associated with underexcretion of uric acid). Kidney disease is also seen due to accumulation of uric acid in the tubules. The disease mostly affects males, and is frequently treated with allopurinol, an inhibitor of xanthine oxidase. Xanthine oxidase catalyzes the sequential oxidation of hypoxanthine to xanthine to uric acid.
    A defect in urea synthesis (choice A) would result in the accumulation of ammonia.

    Phenylketonuria is a disease in which tyrosine cannot be produced from phenylalanine (choice C). It is characterized by a musty body odor and mental retardation.

    Defective topoisomerases (choice D) would affect DNA unwinding, and therefore replication.

    Leukotrienes (choice E) are potent constrictors of smooth muscle and would more likely lead to bronchoconstriction.

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