Block 6 The Buxbaum Files

34 Questions | Total Attempts: 630

SettingsSettingsSettings
Please wait...
Block 6 The Buxbaum Files

The names have been changed to protect the innocent. . . .


Questions and Answers
  • 1. 
    Differential scanning calorimetry (DSC) is a technique to follow phase transitions  (like melting). Two chambers -one with buffer only, the other also containing the sample - are heated in parallel and the energy required for changing the temperature in both chambers is compared. As the sample approaches a phase transition temperature, it requires more energy to heat than the buffer (“excess heat" measured in J/(mol). Once the temperature passes the transition temperature, the excess heat drops to near 0 J/(mol) again. The experiment depicted below measures the “melting” (Lipid A --  > lipid B transition) in two samples of phosphatidylcholine Liposomes. The samples differ in the fatty acids that make up the phospholipid. To go from A to B, you have to replace
    • A. 

      Stearic with oleic acid

    • B. 

      Oleic with stearic acid

    • C. 

      Stearic with palmitic acid

    • D. 

      Palmitic with stearic acid

    • E. 

      Oleic with palmitoleic acid

  • 2. 
    A.B. ill1-5 in above pedigree, was rather lethargic and unwilling to feed. On the 5th day of his life he was found unconscious in his bed, undergoing seizures. Blood tests revealed elevated concentrations of ammonia, glutamine, alanine and orotic acid. Since one of his uncles had died n early childhood blood ammonia levels were measured in all surviving family members (indicated from white (normal; over gray (slightly elevated) to black (very high) in the pedigree). Which of the following enzymes is most likely affected in this family?
    • A. 

      Ornithine transcarbamoylase

    • B. 

      Argininosuccinate synthetase

    • C. 

      Argininosuccinate lyase

    • D. 

      Argininase

    • E. 

      Carbamoylphosphate synthetase

  • 3. 
    For your research project you want to isolate the enzyme argininosuccinate synthetase in the laboratory. Which starting material would you use?
    • A. 

      Brain peroxisome

    • B. 

      Brain nuclei

    • C. 

      Liver cytosol

    • D. 

      Liver mitochondria

    • E. 

      Kidney microsomes

  • 4. 
    You are a young physician working with a disaster relief organization. You have been send to a developing country where a recent civil war has caused wide-spread malnutrition. A patient presents with weakness, muscle wasting, seizures, confusion, tachycardia and vomiting. There is edema in the lower body, which according to relatives has started in the feet and, moving upward, has now reached the thighs. This hypovitaminosis will affect the metabolism of which of the following amino acids:
    • A. 

      Asp and Glu

    • B. 

      Val, Ile and Leu

    • C. 

      Ser

    • D. 

      Pro and Arg

    • E. 

      Met

  • 5. 
    A.B. is a 40 a old female patient complaining of kidney stones. Microscopic examination of urine reveals hexagonal crystals. Elemental analysis shows that the crystals are made of a compound that contains sulphur. Family history reveals an autosomal recessive inheritance. The patient should NOT be treated by:
    • A. 

      Low protein diet

    • B. 

      Agents that increase urine pH (e.g. penicillamine)

    • C. 

      High fluid intake

    • D. 

      Surgical removal of stones

    • E. 

      Diuretics

  • 6. 
    Which amino acid plays an important role in pH-regulation in the kidney?
    • A. 

      Glutamine (Gln, Q)

    • B. 

      Asparagine (Asn, N)

    • C. 

      Lysine (Lys, K)

    • D. 

      Arginine (Arg, R)

    • E. 

      Tryptophan (Trp, W)

  • 7. 
    K.L. a 58a old female comes to your family practice because she is not feeling well. She has been suffering from dizziness, weakness and nausea with occasional vomiting for about 3 mo. She also complains about shortness of breath and tingling and numbness in her extremities. Physical exam reveals slightly icteric eyes, hepatosplenomegaly, glossitis, loss of balance, toss of vibratory and position sense in Legs. Lab results: Macrocytic, hypochromic anemia, leucopenia with hypersegmented neutrophils, thrombocytopenia, hyperbilirubinemia. There is no hydrochloric acid in stomach juice Your patient is suffering from
    • A. 

      Rickets

    • B. 

      Pellagra

    • C. 

      Ben-beri

    • D. 

      Pernicious anemia

    • E. 

      Scurvy

  • 8. 
    A 2-week-old infant presents with vomiting, lethargy and convulsions without evidence of an infectious process. Laboratory examination reveals hyperammonemia with alkalosis. Glutamine, citrulline and arginine are found elevated in the blood. The enzyme that is most likely deficient in this patient is:
    • A. 

      Arginase

    • B. 

      Carbamoyl-phosphate synthetase I

    • C. 

      Arginosuccinate lyase

    • D. 

      Ornithine transcarbamoylase

    • E. 

      Arginosuccinate synthetase

  • 9. 
    A nurse notices that the urine produced by a newborn infant has the odor of maple syrup. Which of the following pathways is most likely defective?
    • A. 

      Metabolism of branched-chain amino acids

    • B. 

      Metabolism of aromatic amino acids

    • C. 

      Metabolism of sulfur-containing amino acids

    • D. 

      Transformation of carbohydrates to amino acids

    • E. 

      One-carbon transfer reactions

  • 10. 
    A 1-year-old child with mental retardation has a deficiency of dihydrobiopterin reductase. This enzyme deficiency leads to an increased blood level of:
    • A. 

      Tyrosine

    • B. 

      Methionine

    • C. 

      Glucocerebroside

    • D. 

      Glycine

    • E. 

      Phenylalanine

  • 11. 
    A patient reports to you that he has had aches and pains in his muscles for the past seven days. A blood test shows increased levels of creatine kinase MM, fatty acids and also myoglobin. A second blood sample, this time taken after an overnight fast, revealed low levels of blood glucose and elevated very low density lipoprotein (VLDL). This patient most likely has which of the following conditions?
    • A. 

      Essential amino acid deficiency

    • B. 

      Type 1 glycogen storage disease

    • C. 

      Acute alcohol toxicity

    • D. 

      Carnitine acyltranferase deficiency

    • E. 

      Elevated insulin levels, which cause the hypoglycemia and increase fatty acid mobilization from adipose tissue

  • 12. 
    A 29-year-old male decides to go on the Atkins diet. After approximately a month on the diet he complains of having what he describes as bad breath. What would be the biochemical findings in this patient?
    • A. 

      Increased synthesis of fatty acids in adipose tissue due to excess free fatty acids released from adipose tissue

    • B. 

      Decreased gluconeogenesis due to lack of activation of pyruvate carboxylase

    • C. 

      Decreased levels of free fatty acids and undetectable ketone bodies in the plasma due to inactivation of LPL

    • D. 

      Increased synthesis and recycling of fatty acids by the liver leading to increased adipose tissue storage of fats

    • E. 

      Increased beta-oxidation due to increased activity of hormone sensitive lipase with subsequent increase in ketone bodies in plasma

  • 13. 
    What is the importance of citrate in fatty acid metabolism?
    • A. 

      Activation of fatty acid synthetase

    • B. 

      To act as a precursor for addition of one carbon units

    • C. 

      Activation of acetyl-CoA carboxylase

    • D. 

      To add the activated carbon dioxide in the formation of malonyl-CoA

    • E. 

      Activation of carnitine acyl transferase

  • 14. 
    The reducing equivalents necessary for fatty acid synthesis are produced during the conversion of:
    • A. 

      Glyceraldehyde-1, 3-bisphosphate to 3-phosphoglycerate

    • B. 

      Glucose-6-phosphate to ribulose-5-phosphate

    • C. 

      Glucose-6-phosphate to fructose-6-phosphate

    • D. 

      Citrate to malate

    • E. 

      Pyruvate to lactate

  • 15. 
    When excess acetyl-CoA, produced by the liver, cannot be used by the TCA cycle, it accumulates in the body as:
    • A. 

      Glucose

    • B. 

      Triglycerides

    • C. 

      P-hydroxybutarate

    • D. 

      Acetyl-CoA

    • E. 

      Glycogen

  • 16. 
    A patient presents to your clinic complaining of weakness and pain in the muscle and a general lack of energy. A blood test shows that he has high levels of creatine kinase and myoglobin. Urine analysis reveals very low levels of acetoacetate. This patient most likely has which of the following?
    • A. 

      Complete absence of medium chain acyl-CoA dehydrogenase

    • B. 

      Deficiency in one of the enzymes in the ketone body synthetic pathway

    • C. 

      Carnitine deficiency

    • D. 

      A low fat, high carbohydrate diet

    • E. 

      Decreased production of insulin

  • 17. 
    Dr Buxbaum   The DRI of Vitamin A for an 18a old ♂ is: EAR 625 ug/d, RDA 900 ug/d and UL 2800 ug/d. A patient of that group taking on average 950 ag/d will suffer from symptoms of
    • A. 

      Poisoning with a probability of about 50%

    • B. 

      Poisoning with a probability of about 2%

    • C. 

      Deficiency with a probability of about 98%

    • D. 

      Deficiency with a probability of about 2%

    • E. 

      Deficiency with a probability of about 50%

  • 18. 
    A 4-month-old male was admitted to the hospital in a coma. Blood analysis taken on admission revealed a blood glucose of 15 mg/dL (normal 60-100 mg/dL).  He had no acidosis or ketosis. A 24 hour fast produced a dramatic drop in blood glucose and a rise in serum triglycerides. Liver and muscle biopsy showed accumulation of fat. This infant most likely has
    • A. 

      Fructose intolerance

    • B. 

      Hormone sensitive lipase deficiency

    • C. 

      Type 1 glycogen storage disease

    • D. 

      Fat malabsorption

    • E. 

      Carnitine deficiency

  • 19. 
    A.B. is on chitosan to help him reduce weight. He may have to supplement his diet with which of the following compounds?
    • A. 

      A

    • B. 

      B

    • C. 

      C

    • D. 

      D

    • E. 

      E

  • 20. 
    A 5mo old female was transferred to an emergency room in a rapidly deteriorating condition. She was born in Ville de Saguenay (Quebec), birth was uneventful. However, she failed to thrive. Lab: Glutamic:pyruvic transaminase (GPT), aspartate aminotransferase (AST), ammonia and creatinine levels in blood were elevated, attending physicians noticed a strong cabbage-like smell originating from her. The most likely diagnosis is
    • A. 

      Hyperlysinemia

    • B. 

      Tyrosinemia I

    • C. 

      Cystinuria

    • D. 

      Methylmalonic aciduria

    • E. 

      Glycine cleavage enzyme deficiency

  • 21. 
    A 54-year-old male presents himself at an outpatient clinic complaining of weakness, lassitude and a weight loss of 20kg over the last 7mo. On Dr. E. Buxbaum examination pulse and respiratory rate, EKG and chest X-ray appeared normal. Blood pressure was 145/75 mm Hg, liver was firm and moderately enlarged (2 fingers below costal margin). Upon questioning the patient remarked that his skin had become darker over the last years, a change he attributed to working outdoors. He denied exposure to toxic chemicals or metal fumes. Lab results: Fasting blood glucose 7.6mM (3.9–6.1mM), Urine glucose(random) + (0), total serum bilirubin 20 µM (2.6–26µM), Haemoglobin 16.5 g/dl (14.0–18.0g/dl) Haematocrit 52% (40–54%), Methemoglobin 0 (0), Serum iron 43 µM (7.2–28.6µM), total iron binding capacity (TIBC) 56µM (47–77µM), aspartate aminotransferase (AST) 50U/l(5–34U/l), alanine aminotransferase (ALT) 45U/l(5–50U/l), Serum ferritin 463µg/l (20–250 µg/l). On the basis of these results a liver biopsy was performed. Microscopic examination revealed fatty vacuolisation of the hepatocytes and moderate deposits of hemosiderin in their cytoplasm. Your diagnosis would be
    • A. 

      Hemochromatosis

    • B. 

      Wilson’s disease

    • C. 

      Menke’s kinky hair syndrome

    • D. 

      Keshan-disease

    • E. 

      Kashin-Beck disease

  • 22. 
    When vitamin B12 is deficient, pernicious anemia results from the:
    • A. 

      Lack of N5, N10-methylenetetrahydrofolate

    • B. 

      Accumulation of S-adenosylmethionine

    • C. 

      Lack of methionine

    • D. 

      Lack of 5-adenosylmethionine

    • E. 

      Accumulation of homocysteine

  • 23. 
    A 47a old male comes to the emergency room with bleeding gums, hemarthrosis (blood collection) in the right knee, and hematemesis (vomiting blood). He is homeless, admits being drunk at least 5 times a week. His diet mainly consists of leftovers from fast food restaurants. Medical history: Food poisoning treated with ampicillin 2 weeks ago. Physical exam: emaciated, with poor hygiene, ecchymosis (large patches of bleeding into skin). Lab: Hb 9.7mg/d1. Normal platelet count, fibrinogen and thrombin time. PT and PTT prolonged. The patient needs supplementation with
    • A. 

      Vitamin A

    • B. 

      Vitamin K

    • C. 

      Vitamin C

    • D. 

      Copper

    • E. 

      Iron

  • 24. 
    Joseph is a 55 year old man with pellagra, characterized by dementia, diarrhea and dermatitis. Which of the following vitamin deficiencies result in pellagra?
    • A. 

      Riboflavin

    • B. 

      Niacin

    • C. 

      Vitamin K

    • D. 

      Vitamin B12

    • E. 

      Vitamin E

  • 25. 
    Tim is s 52 year old man with a long-standing history of alcohol abuse, who comes to see his primary care physician because he has been losing balance lately. His wife related to the doctor that his memory is getting worse. Based on the patient's report what is the most likely Vitamin or mineral deficiency that would explain these symptoms?
    • A. 

      Vitamin D

    • B. 

      Calcium

    • C. 

      Vitamin A

    • D. 

      Vitamin C

    • E. 

      Thiamine

Related Topics
Back to Top Back to top