Answer- Vitamin B12 deficiency is associated with sub acute combined degeneration of spinal cord. Peripheral nerves are usually affected first, and patients complain initially of paresthesias. The posterior columns next become impaired, and patients complain of difficulty with balance. In more advanced cases, cerebral function may be altered as well. An accumulation of Methylmalonyl-CoA in serum, has been suggested as a possible cause of neurologic defects seen in cobalamin deficiency by decreasing lipid synthesis.
Impaired biosynthesis of phosphatidyl choline due to decreased levels of methionine and S-adenosylmethionine (SAM) may also play a role in the neurologic symptoms of cobalamin deficiency by compromising the repair of demyelination.
Q.2- Which vitamin participates in the absorption of calcium from gut?
Answer- Vitamin D has an active role in the absorption of calcium from gut. Vitamin D promotes the synthesis of calbindin protein that promotes the absorption of calcium from gut. This action is brought about through nuclear receptors. it acts like a steroid hormone, binding to nuclear receptors and enhancing gene expression, although it also has rapid effects on calcium transporters in the intestinal mucosa
Q.3- A 2-year- old child presents with chronic cough, bronchitis, growth failure, chronic diarrhea and growth failure. A deficiency of which vitamin should be considered?
Answer- The child is probably suffering from Vitamin A deficiency.
The child has chronic cough, bronchitis, growth failure and passage of light-colored, foul-smelling stools. All these symptoms are due to increased susceptibility to infections as a result of the keratinization of mucous membranes in the respiratory, GI, and urinary tracts. The thickened mucosa cracks easily and the risk for bacterial infections increases. During infection the synthesis of retinol binding protein is reduced in response to infection since it is a negative ‘Acute phase protein’, that results in decreased circulatory concentration of the vitamin with further deterioration of the immune system.
Q.4- A 2-year- old child has been brought to Pediatric O.P.D with the complaint of painful and difficult walking. General examination reveals bow legs and prominent costochondral junctions. Which vitamin supplementation should be given as a part of the treatment?
Answer- Vitamin D supplementation is needed as a part of treatment since the child seems to be suffering from Rickets. In young infants, rickets causes softening of the entire skull (Craniotabes). In older infants with rickets, sitting and crawling are delayed, as is Fontenelle closure; there is bossing of the skull and costochondral thickening. Costochondral thickening can look like bead like prominences along the lateral chest wall (rachitic rosary). In children 1 to 4 yr, epiphyseal cartilage at the lower ends of the radius, ulna, tibia, and fibula enlarge; Kyphoscoliosis develops, and walking is delayed. In older children and adolescents, walking is painful; in extreme cases, deformities such as bowlegs and knock-knees develop.
Q.5- Which vitamin deficiency is associated with Neural tube defects?
Answer- Neural tube defects are observed are due to maternal folic acid deficiency. Neural Tube Defects (NTDs) are birth defects of the brain and the spinal cord (malformations of the brain and spinal cord, causing anencephaly, spina bifida or encephalocele).It has been demonstrated that periconceptional (before and during the first 28 days after conception) supplementation of women with folic acid can decrease the risk of neural tube defects. Therefore, a daily intake of 400 µg folic acid in addition to a healthy diet 8 weeks prior to and during the first 12 weeks after conception is recommended. There is evidence that adequate folate status may also prevent the incidence of other birth defects, including cleft lip and palate, certain heart defects and limb malformations. To reduce the risk of neural tube defects, cereal grains are fortified with folate in some countries.
Q.6- Which vitamin deficiency is associated with egg white injury?
Answer- Raw egg whites contain Avidin, a glycoprotein that strongly binds to biotin and prevents its absorption. Thus, the ingestion of large quantities of raw egg white over a long period can result in a biotin deficiency.
Q.7- Name the coenzyme for the reaction for the conversion of Pyruvate to alanine.
Answer- Pyruvate to Alanine conversion is catalyzed by Transaminase (SGPT- Alanine transferase), that requires vitamin B6-P as a coenzyme.
Q.8- The bone marrow smear of a strict vegetarian female patient, presenting with weakness, fissured tongue and paralysis reveals megaloblastic anemia. Which vitamin deficiency is expected?
Answer- The patient is suffering from megaloblastic anemia. The cause seems to be B12 deficiency. Although it is synthesized exclusively by microorganisms, for practical purposes vitamin B12 is found only in foods of animal origin, there being no plant sources of this vitamin. This means that strict vegetarians (Vegans) are at risk of developing B12 deficiency.
Q.9- A 56 – year-old male on Isoniazid therapy for tuberculosis has developed rashes on the exposed parts of the body. What is the probable cause for these rashes?
Answer- The patient has developed pellagra. Prolonged treatment with the anti-tuberculosis drug, Isoniazid, can cause niacin deficiency. Isoniazid may induce a state of pyridoxine deficiency by combining with pyridoxine and generating inactive isoniazid-pyridoxal hydrazones, thus depleting the supply of pyridoxine. Pyridoxine is needed in the endogenous pathway of niacin synthesis. Thus diminished synthesis of niacin ultimately produces pellagra.
Q.10- Why is it said that babies undergoing phototherapy for physiological jaundice are prone to develop riboflavin deficiency?
Answer- Riboflavin is stable when heated and is not easily destroyed in the ordinary processes of cooking but it is light-sensitive so it is degraded easily by light, that is why infants undergoing phototherapy for jaundice get prone to this deficiency. Loss of riboflavin is also seen if foods are left out in sunlight or in UV light. Because of this light sensitivity, riboflavin rapidly disappears from milk kept in glass bottles exposed to the sun or bright daylight (85% within 2 hours).
Q.11- A child from a very poor socio economic background has reported with loss of vision.Make a probable diagnosis. What is the underlying cause for blindness?
Answer- As the child is from a family with poor socio economic background, perhaps he is suffering from vitamin A deficiency.The earliest symptom of vitamin A deficiency is impaired dark adaptation, or night blindness. Severe deficiency causes xerophthalmia, ultimately resulting in corneal ulcers, scarring and blindness.
Q.12- What is the possible link between intake of polished rice and sudden cardiac failure?
Answer- The link between intake of polished rice and sudden cardiac failure is thiamine deficiency (wet beriberi).Polished rice or highly refined carbohydrates are poor sources of thiamine.
Thiamine deficiency is most commonly observed in chronic alcoholics or people subsisting on polished rice or high carbohydrate refined diets.
Q.13- Name an FMN dependent enzyme
Answer- L- amino acid oxidase that catalyzes the oxidative decarboxylation of amino acids requires the presence of FMN as a coenzyme.
Q.14- What are folate antagonists? Enlist a few clinically important Folate antagonists.
Answer- – Folate antagonists were originally developed as antileukemic agents, but are now being used and/or investigated in the treatment of a wide range of cancerous and non-cancerous diseases. Sulfanilamide and Trimethoprim are antibiotics, Pyrimethamine is antimalarial while Methotrexate is an anticancer drug.
Q.15- Cancer patients on Methotrexate therapy, develop Glossitis and oral ulcers, what is the possible reason?
Answer- Methotrexate, an analog of 10-methyl-tetrahydrofolate, inhibits dihydrofolate reductase and has been exploited as an anti-cancer drug. Methotrexate blocks the cell’s ability to regenerate THF, leading to inhibition of these biosynthetic pathways. The lack of nucleotides prevents DNA synthesis, and these cancer cells cannot divide without DNA synthesis.
Unfortunately, the effects of Methotrexate are nonspecific and other rapidly dividing cells such as epithelial cells in the oral cavity, intestine, skin, and blood cells are also inhibited. This leads to the side effects associated with methotrexate (and other cancer chemotherapy drugs) such as mouth sores, low white blood cell counts, stomach upset, hair loss, skin rashes, and itching.
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