Category: Vitamins

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Low Glutathione reductase activity

Q- A 45-year-old female presents to her primary care doctor with fatigue and tingling/numbness in her extremities (bilateral). Examination reveals a beefy red and fissured tongue. Further evaluation reveals a low Glutathione reductase activity in the red blood cells. Which of the following vitamin deficiencies could have caused her symptoms? A.Vitamin C B. Niacin C. Vitamin B2 D. B6-P E. Vitamin B12   The correct option is C- vitamin B2. The patient is most probably suffering from Vitamin B2 deficiency (Riboflavin deficiency). Most prominent effects of vitamin B2 deficiency are seen on the skin, mucosa and eyes. The characteristic symptoms...

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Hypoglycemia due to Biotin deficiency?

A 32-year-old body builder has decided to go on a diet consisting of egg whites to ensure only proteins for muscle growth. After a few weeks he experiences decreased energy and is found to be hypoglycemic. A nutritionist tells the patient that he most likely has the deficiency of vitamin Biotin. Which of the following enzymes is unable to catalyze its step in synthesizing glucose from pyruvate? A) Pyruvate carboxylase B) Phospho enol pyruvate carboxy kinase C) Glucose-6-phosphatase D) Fructose 1, 6 bisphosphatase E) Phosphoglycerate kinase. The correct answer is- A) – Pyruvate carboxylase. Biotin deficiency is very common in...

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Free radical injury and antioxidants

The organic solvent Carbon tetra chloride (CCl4) is used in the dry cleaning industry. The Carbon tetra chloride (CCl4) is metabolized in the body by cytochrome P450 enzyme system to form a free radical species CCl3– . This highly reactive species causes a chain reaction of lipid peroxidation, particularly in the liver, that can lead to hepatocellular necrosis. The cells have developed enzymes and other molecules to help them protect against the free radical damage. Some dietary components also act as anti-oxidants. Which of the following dietary components can provide some protection against free radical injury? A. Glutamine B. Linoleic...

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Angular stomatitis and impaired TCA cycle activity

Case details A postoperative patient on intravenous fluids develops lesions in the mouth (angular stomatitis). Urinalysis indicates an excretion of 15 μg riboflavin/mg creatinine, which is abnormally low. Which of the following TCA cycle enzymes is most likely to be affected? A. Citrate synthase B. Isocitrate dehydrogenase C. Fumarase D. Malate dehydrogenase E. Succinate dehydrogenase Answer- The correct answer is- E- Succinate dehydrogenase Angular stomatitis and low excretion of riboflavin are indicators of underlying Riboflavin deficiency, hence the activities of only Riboflavin requiring enzymes would be affected . Riboflavin functions in several different enzyme systems. Two derivatives, riboflavin 5′ phosphate (flavin...

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Biotin deficiency- A case report

Case details A 23-year-old body builder visits his physician with complaints of fatigue, depression, insomnia, hair loss and dry skin. He tells the physician he has been “bulking up” for an upcoming competition, and his meals consist mostly of eight raw eggs along with low-fat milk. The physician suspects biotin deficiency given the patients’ diet and symptoms. Which of the following is biotin required for? A. The formation of cis-retinal B. Transfer of 1-carbon units C. Hydroxylation reactions D. Carboxylation of pyruvate E. Decarboxylation of α-Keto acids Answer- D- Carboxylation of pyruvate is the right answer. Biotin is required for...

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Co-factor for GABA, Dopamine, and Histamine ?

The neurotransmitters GABA, dopamine, and histamine are all derived from an amino acid precursor. The generation of these neurotransmitters from the appropriate amino acids requires which one of the following cofactors? A. NAD+ B. B1 C. B2 D. B6 E. B12 Answer- The correct answer is B6. All the neurotransmitters in question are derived by a common process of decarboxylation that requires the presence of vitamin B6 as a coenzyme. 1) GABA is derived from Glutamic acid (figure-1) Figure-1- Glutamic acid to GABA conversion. The reaction is catalyzed by glutamic acid decarboxylase that requires the presence of B6-P as a...

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Answer- Case study- Oral contraceptives induced vitamin deficiencies

Case Details Oral contraceptives are known to lower blood levels of folate and vitamin B6. Which of the following conversion processes might be directly affected? A. Ornithine to Citrulline B. Histidine to histamine C. Glutamate to Glutamine D. Propionyl co A to Methyl malonyl co A E. Phenyl alanine to Tyrosine Answer- B- The correct answer is conversion of Histidine to histamine. The reaction is catalyzed by decarboxylase that requires B6-P as a cofactor (Figure-1) that gets deficient in women upon long-term oral contraceptive usage. Folic acid is not required in this reaction. Figure-1- Decarboxylation of Histidine is carried out...

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Case- Oral contraceptive induced Vitamin deficiencies

Question of the day Oral contraceptives are known to lower blood levels of folate and vitamin B6. Figure- Oral contraceptives Which of the following conversion processes might be directly affected ? A. Ornithine to Citrulline B. Histidine to histamine C. Glutamate to Glutamine D. Propionyl co A to Methyl malonyl co A E. Phenyl alanine to Tyrosine For answer follow the link http://usmle.biochemistryformedics.com/answer-case-study-oral-contraceptives-induced-vitamin-deficiencies/ Please help Biochemistry for Medics by “CLICKING ON THE ADVERTISEMENTS” every time you visit us. Thank you!

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Case study- Pellagra

QUESTION OF THE DAY A 56 – year-old male on Isoniazid therapy for tuberculosis has developed rashes on the exposed parts of the body. History is also suggestive of disoriented memory and diarrhea. The patient has been diagnosed with pellagra. Pellagra is known to manifest in individuals deficient of niacin. What is the correlation of Isoniazid therapy and niacin deficiency? A. Isoniazid inhibits biological activation of niacin B. Isoniazid prevents absorption of niacin C. Isoniazid promotes excessive excretion of niacin D. Isoniazid inhibits endogenous synthesis of niacin E. Isoniazid acts a competitive inhibitor of niacin Answer- D- Isoniazid inhibits the...

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Case study- Pellagra- A 56–year-old male on Isoniazid therapy for tuberculosis …..

Niacin and Pellagra Basic concept Niacin (nicotinic acid and nicotinamide) is also known as vitamin B3. Both nicotinic acid and nicotinamide can serve as the dietary source of vitamin B3. Niacin is a pyridine carboxylic acid that is converted into an amide in the body. Niacin is not a true vitamin in the strictest definition since it can be derived from the amino acid tryptophan. However, the ability to utilize tryptophan for niacin synthesis is inefficient (60 mg of tryptophan are required to synthesize 1 mg of niacin). Also, synthesis of niacin from tryptophan requires vitamins B1, B2 and B6...

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