Vitamin

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manjinder
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138177
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Vitamin
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2012-02-27 21:22:54
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Vitamin
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Vitamin
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  1. Water soluble vitamine
    The Real News for Political Pundits and Criminals
    • B1 (thiamine:TPP)
    • B2 (riboflavin: FAD, FMN)
    • B3 (niacin:NAD+)
    • B5 (Pantothenic acid: CoA)
    • B6 (pyridoxine: PLP)
    • B12 (cobalamin)
    • Biotin
    • C (ascorbic acid)

    B12 and folate are the only two stored in liver

    B-complex deficiencies often result in dermatitis, glossitis, and diarrhea
  2. Vitamin A (retinol)
    • 1. antioxidant
    • 2. constituent of visual pigments (retinal)
    • 3. essential for normal differentiation of epithelial cells into specialized tissue (pancreatic cells, mucus-secreting cells)
    • 4. prevents squamous metaplasia
    • 5. used to treat measles and AML, subtype M3; wrinkles and acne
    • 6. found in liver and leafy vegetables

    Deficiency: Night blindness, dry skin

    Excess: Arthralgias, fatigue, headaches, skin changes, sore throat, alopecia. Tertogenic (cleft palate, cardiac abnormalities), so a pregnancy test must be done before isotretinoin is prescribed for severe acne
  3. Vitamin B1 (thiamine)
    Thiamine pyrophosphate (TPP)
    Ber1 Ber1
    Wernicke- Korsakoff (triad)
    • Decarboxylation reactions:
    • 1. pyruvate dehydrogenase
    • 2. alpha-ketoglutarate dehydrogenase (TCA cycle)
    • 3. Transketolase (HMP shunt)
    • 4. Branched-chain AA dehydrogenase

    • Deficiency: impaired glucose breakdown; brain and heart affected first;
    • Triad: confusion, ophthalmoplegia, ataxia + confabulation, personality change, memory loss (permanent). Damage to medial dorsal nucleus of thalamus, mammillary bodies
    • Dry beriberi- polyneuritis, symmetrical muscle wasting
    • Wet beriberi- high-output cardiac failure (dilated cardiomyopathy), edema
  4. Vitamin B2 (riboflavin)
    B2= 2ATP
    cofactor in oxidation and reduction (FADH2)

    Deficiency: Cheilosis (inflammation of lips, scaling and fissures at the corners of the mouth), Corneal vascularization
  5. Vitamin B3 (niacin)
    B3= 3 ATP
    3 D's= diarrhea, dermatitis, dementia
    • Constituent of NAD+, NADP+
    • Derived from tryptophan
    • synthesis requires B6

    Deficiency: Glossitis. Severe deficiency leads to pellagra: caused by Hartnup disease (dec tryptophan absorption), malignant carcinoid syndrome (inc tryptophan metabolism), and INH (dec vit B6)

    Excess: Facial flushing (due to pharmacologic doses for treatment of hyperlipidemia)
  6. Vitamin B5 (pantothenate)
    Essential component of CoA (a cofactor for acyl transfers) and fatty acid synthase

    Deficiency: dermatitis, enteritis, alopecia, adrenal insufficiency
  7. Vitamin B6 (pyridoxine)
    converted to pyridoxal phosphate, a cofactor used in transamination decarboxylation reaction, glycogen phosphorylase. Synthesis of cystathionine, heme, niacin and GABA

    Deficiency: convulsions, hyperirritability, peripheral neuropathy (deficiency inducible by INH and oral contraceptives), sideroblastic anemias due to impaired Hb synthesis and Fe excess
  8. Vitamin B12 (cobalamin)
    cofactor for homocysteine methyltransferase and methylmalonyl-CoA mutase (Odd #C fatty acids)

    Deficiency: Macrocytic, megaloblastic anemia, hypersegmented PMNs, neurologic symptoms (paresthesias, subacute combined degeneration) due to abnormal myelin. Prolonged deficiency leads to irreversible nervous system damage

    • Found in animal products
    • synthesized only by microorganisms.
    • Deficiency is usually caused by malabsorption (sprue, enteritis, Diphyllobothrium latum), lack of intrinsic factor (pernicious anemia, gastric bypass surgery), or absence of terminal ileum (Crohn's disease)
    • Use Schilling test to detect the etiology of the deficiency.
  9. Folic Acid
    • Converted to tetrahydrofolate (THF)
    • important for the synthesis of nitrogenous bases in DNA and RNA

    Deficiency: most common seen in alcoholism and pregnancy; macrocytic, megaloblastic anemia. caused by several drugs (eg phenytoin, sulfonamides, MTX)
  10. S-adenosyl-methionine (SAM)
    • ATP + methionine --> SAM
    • transfers methyl units- required fro the conversion of NE to epinephrine
    • regeneration of methionine (thus SAM) is dependent on vitamin B12 and folate
  11. Biotin
    • cofactor for carboxylation enzymes
    • 1. pyruvate carboxylase: pyruvate (3 C) --> oxaloacetate
    • 2. Acetyl-CoA carboxylase: acetyl-CoA (2 C)--> malonyl-CoA
    • 3. Propionyl-CoA Carboxylase: propionyl-CoA (3C) --> methylmalonyl-CoA

    Deficiency: Rare caused by antibiotic (biotin synthesized by GI bacteria) use or excessive ingestion of raw eggs (egg whites). Dermatitis, alopecia, enteritis
  12. Vitamin C (ascorbic acid)
    Found in fruits and vegetables

    • 1. facilitates iron absorption by keeping iron in Fe2+ reduced state
    • 2. necessary for hydroxylation of proline and lysine in collagen synthesis
    • 3. necessary for dopamine b-hydroxylase, which coverts dopamine to NE

    Deficiency: scurvy- swollen gums, bruising, hemarthrosis, anemia, poor wound healing; weakened immune response.

    Excess: nausea, vomiting, diarrhea, fatigue, sleep problems. Can inc risk of iron toxicity in predisposed individuals (transfusions, hereditary hemochromatosis)
  13. Vitamin D
    • 7 alpha-dehydrocholesterol in skin
    • D2= ergocalciferol- ingested from plants
    • D3= cholecalciferol- consumed in milk, formed in sun-exposed skin
    • 25-OH D3= storage form
    • 1,25 (OH)2 D3 (calcitriol)= active form

    Deficiency: hyopcalcemic tetany, breast milk has dec vit D

    Excess: loss of appetite, stupor, seen in sarcoidosis (inc activation of vit D by epithelioid macrophages)
  14. Vitamin E
    Antioxidant (protects erythrocytes and membranes from free-radical damage)

    Deficiency: inc fragility of erythrocytes (hemolytic anemia), muscle weakness (necrotizing myopathy), posterior column and spinocerebellar tract demyelination (similar to B12 deficiency)
  15. Vitamin K
    • catalyzes gamma-carboxylation of glutamic acid (II, VII, IX, X, protein C and S)
    • synthesized by intestinal flora
    • also activate osteocalcin (inhibits calcification of arteries & cartilage)

    Deficiency: neonatal hemorrhages w/ inc PT and inc PTT but normal bleeding time (neonates have sterile intestine and are unable to synthesize vit K). Chondrodysplasia punctate: leads to aberrant calcification (early or excessive)
  16. Zinc
    essential for the activity of 100+ enzymes. Imp in the formation of zinc fingers (transcription factor motif)

    Deficiency: delayed wound healing, hypogonadism, dec adullt hair (axillary, facial, pubic), dysgeusia (no taste buds), anosmia (inability to perceive odor). May predispose to alcoholic cirrhosis

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