Vitamins Flashcards
Most common cause (MCC) of Biotin deficiency
excessive consumption of raw eggs (contain Avidin, a biotin-binding protein)
MCC of Thiamine deficiency
alcoholism
Alopecia, bowel inflammation, muscle pain
Biotin deficiency
Wernicke (ataxia, nystagmus, ophthalmoplegia) - Korsakoff (confabulation psychosis)
Thiamine deficiency
Beri-beri
Thiamine deficiency
Enzymes requiring Biotin? Clue: “PAP carboxylases”
Pyruvate carboxylase (Gluconeogenesis), Acetyl CoA carboxylase (Fatty acid synthesis), Propionyl CoA carboxylase (Odd-carbon fatty acids, Val, Met, Ile, Thr)
Enzymes requiring Thiamine? Clue: “PAB dehydrogenases + T”
Pyruvate DH (PDH pre-Krebs), Alpha-ketoglutarate DH (Krebs), Branched chain-ketoacid DH (Metabolism of Val, Iso, Leu), Transketolase (HMP shunt)
Diarrhea, dementia, dermatitis, death - the 4 D’s of Niacin deficiency
Pellagra; Niacin is required by many dehydrogenases via NAD(H) or NADP(H)
Deficiency in folic acid most common in
alcoholics, pregnant women (body stores depleted in 3 months)
Enzyme requiring folic acid
Thymidylate synthase (in Thymidine pyrimidine synthesis)
Diseases associated with folic acid deficiency
Homocystinemia (risk of DVT ad atherosclerosis), Megaloblastic anemia, Neural tube defects in fetus
Enzymes requiring Cyanocobalamin (B12)
Homocysteine methyltransferase (Methionine, SAM), Methylmalonyl CoA mutase (Odd carbon fatty acids, Val, Met, Ile, Thr)
Diseases associated with Cyanocobalamin deficiency
Pernicious anemia, Megaloblastic anemia, D. latum infection, Progressive peripheral neuropathy, terminal ileum resection, chronic pancreatitis, vegan diet
MCC of Pyridoxine deficiency
Isoniazid therapy
Enzymes requiring Pyridoxine
AST, ALT (Protein catabolism), Aminolevulinate synthase (Heme synthesis)
Diseases associated with Pyridoxine deficiency
Sideroblastic anemia, Cheilosis or stomatitis, Convulsions
Magenta-colored tongue, Corneal neovascularization, cheilosis or stomatitis
Riboflavin deficiency
Enzymes requiring Ascorbate
Prolyl and lysyl hydroxylases (Collagen synthesis), Dopamine hydroxylases (Catecholamine synthesis)
Painful glossitis, bleeding gums, easy bruising (perifollicular hemorrhage), poor wound healing, anemia
Scurvy (Vit. C deficiency), MCC: deficiency in diet
Enzymes requiring Panthothenic acid/CoA
Fatty acid synthase and Fatty acyl Coa synthetase (Fatty acid metabolism), PDH, Alpha-ketoglutarate DH
Rickets (children), Osteomalacia (adults)
Vit D deficiency
Rate limiting enzyme in Vit D synthesis and activation, regulated by PTH
1alpha-hydroxylase in the proximal renal tubules
Active form of Vitamin D
1,25-dehydroxycholecalciferol or “calcitriol”
Drug class that inhibits osteoclast action (resorption of bone)
Bisphosphonates
Teratogenic derivative of Vitamin A, used in the treatment of acne
Isotretinoin
The three vitamin A structures difering on the functional group on carbon 1
retinol (-OH), retinoic acid (-COOH), retinal (-aldehyde)
Family of proteins acting as Vitamin A intracellular receptors, regulating transcription via HREs
Zn-finger proteins
Form of retinal involved in vision
cis-11-retinal, cofactor in converting opsin to rhodopsin (a 7-pass receptor coupled to the trimeric G protein “Transducin”, Gt)
Light stimulation of rod cell causes (depolarization/hyperpolarization?)
Hyperpolarization. Light stops release of glutamate that is inhibiting the optic nerve bipolar cell = initiation of signal into the brain
Bitot spots (conjunctival buildup of keratin debris), night blindness, follicular hyperkeratosis, alopecia
Vitamin A deficiency
Acanthocytosis (increased acanthocytes/spur cells/spiculated RBCs), peripheral neuropathy, ataxia, retinitis pigmentosum
Vitamin E deficiency
High blood levels of Vitamin E causes ____ in patients given Warfarin
Hemorrhage
Factors II (prothrombin), VII, IX, X, and anticoagulant proteins C and S, require Vit K along with Ca in this process
Gamma-Carboxylation by Gamma-Glutamyl Carboxylase (cotranslational modification); this process is antagonized by Warfarin and Dicoumarol
Bleeding time in Vit K and Vit C deficiency
Vit K: normal BT, Vit C: increased BT
Prothrombin time in Vit K and Vit C deficiency
Vit K: increased PT, Vit C: normal PT
Full anticoagulant activity by Warfarin and Dicoumarol (via inhibition of gamma-carboxylation) is seen after ___ days
2-3 days. Give Heparin (activator of antithrombin III) to provide short-term anticoagulation
Only signaling molecule involved in the visual cycle of photoreceptor cells
CGMP phosphodiesterase (inactivates CGMP upon presence of Light)
Anticonvulsant that decreases activity of Vitamin K
Phenytoin (phenyl hydantoins)
