Term
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Definition
organic cmpds-small quants requried
fat & H2O soluble |
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Term
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Definition
| A( retinoids), D (cholecalciferol), E (tocopherols) and K (phylloquinone) |
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Term
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Definition
A( retinoids), D (cholecalciferol), E (tocopherols) and K (phylloquinone)
stored in either adipose tissue or lvier; precursor of D found in epidermis & dermis |
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Term
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Definition
| absorbed with dietary fat |
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Term
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Definition
majority synthesized by body
Synthesized endogenously from cholesterol; also dietary concentrations of provitamin D (7-dehydrocholesterol) inversely associated with age
Sunscreen use can reduce production of previtamin D3 from provitamin D
can get from dietary abs (packaged into CM's) |
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Term
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Definition
| much synthesized by colonic bacteria |
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Term
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Definition
thiamin, riboflavin, niacin, B6, B12, pantothenic acid, biotin, folic acid, vitamin C
fct primarily as coenzymes in biochemical rxns
not stored in the body |
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Term
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Definition
| *related to lipid alcohol, retinol, incl provitamin A carotenoids (dietary precursors) |
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Term
| retinol binding protein and transthyretin |
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Definition
transport retinol in the plasma
transthyretin protects circulating rtinol from filtration by kidney |
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Term
| cystolic retinol binding protein (CRBP) |
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Definition
| transports retinol within cells |
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Term
| retinoid storage when vitamin A status is adequate |
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Definition
| 50-80% storage in the liver as retinyl esters |
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Term
| kidneys' role in retinol processing |
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Definition
primary organ of RBP clearance and catabolism
chronic renal disease associated w/ abn elevation of plasma retinol and RBP |
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Term
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Definition
| B-carotene is converted into this after it diffuses into enterocytes |
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Term
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Definition
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Term
| retinoid processing in the SI |
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Definition
| packaged as retinols, with absorbed lipids into CM's, form mixed micelles |
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Term
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Definition
| binding protein that retinol binds in the small intestine, allows it to X into plasma with fat (as a CM) |
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Term
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Definition
| site of RE's storage (retinyl-palmitate) |
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Term
| oxidative cleavage of B-carotene |
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Definition
products: retinal
retinal--> retinol + retinoic acid |
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Term
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Definition
| active (vitamin A) for cell growth & differentiation |
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Term
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Definition
| 1) 11-cis retinal: opsin 2) form rhodopsin (visual purple) 3) hv causes opsin conf change 4) regenerate all trans-retinal and intiate nerve impulse for sight |
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Term
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Definition
| transmembrane pt spanning IC disc membrane or rods & cones |
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Term
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Definition
vision in dimlight
dec night vision associated w vit A deficiency |
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Term
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Definition
| differentiation of colors |
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Term
| retinoic acid role in cell growth & differentiation |
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Definition
| fcts by binding to ligand-inducible transcription factors that activate or repress downstream target gene |
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Term
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Definition
| RXR and RAR heterodimer bound DNA binding domain of retinoic acid response element (RARE). |
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Term
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Definition
no retinoic acid present
inhibit transcription |
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Term
| RAR: retinoic acid: activator |
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Definition
transcription activated
conformational change in RAR that releases repressor and recrutis activators
histone acylator--> stim transcription |
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Term
| genes requiring retinoic acid for differntiation |
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Definition
structural proteins (skin keratins)
extracellular matrix (laminin)
enzymes (EtOH dehydrogenase, transglutaminases)
retinol-binding proteins and receptors |
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Term
| retinoic acid role in embryogenesis |
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Definition
required for normal limb development
formation of heart, eyes, ears
excess--> teratogenic |
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Term
| vitamin A role in immune function |
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Definition
required for normal fct
dec cell-mediated and Ab-mediated immune responses w/ deficiency
immune responses restored after supplementation (ie impaired signaling pathways) |
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Term
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Definition
Class of >600 lipid-soluble compounds
Not essential but precursors to retinoids (which are essential)
Pigmented from yellow to red (think carrots, red peppers)
Plants only synthesize carotenoids; provide 1/3 of dietary intake in developed countries; vast majority of intake in developing countries
common ones: b-carotene, a-carotene, lycopene, lutein |
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Term
| assessment of Vitamin A status |
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Definition
plasma concentration- no change w/ changes in body reserves
dec plasma retinol--> deficiency
examine conjunctiva for changes in epidermis |
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Term
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Definition
Nightblindness early sign
Leads to dedifferentiation of epithelial cells, epithelial keratinization, poor appetite, poor growth, xerophthalmia |
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Term
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Definition
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Term
| Epithelial keratinization |
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Definition
| occurs in the epidermis/dermis where oil-producing cells are replaced with keratin |
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Term
| manifestations of xeropthalmia |
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Definition
early conjunctival xerosis
Bitot's spots
keratomalacia |
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Term
| early conjunctival xerosis |
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Definition
| dryness of conjunctival surface |
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Term
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Definition
| single or multiple areas of desquamated, keratinized conjunctival cells together with lipid accumulation; not unique to vitamin A deficiency unless accomponanied by conjunctival xerosis; temporally (rather than nasally) situated..foamy portions/reversible |
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Term
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Definition
| entire thickness of cornea becomes cloudy, geleatinous mass; in very young children, may develop rapidly in absence of xerosis or Bitot's spot formation. Minimal reaction in surruounding tissue & lack of discharge from eye are characteristic and assist in differntiation from other conditions. Blindness results/irreversible |
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Term
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Definition
acute or chronic overconsumption of preformed vitamin A, not carotenoids
food faddism (eat lots of liver ) and OD on dietary supplements |
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Term
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Definition
| nausea, vomiting and headache due to raised intracranial pressure, peeling of skin |
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Term
| chronic vitamin A poisoning |
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Definition
| loss of weight, low-grade fever, tenderness over long bones, pruritic rash, bright red marginal discoloration of gingiva |
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Term
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Definition
| orange tinge to skin; sclerae remain clear, distinguishing the conditon from jaundice; diets high in carotenes; no serious negative effects |
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Term
| formation of active vitamin D from provitamin D |
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Definition
| cholesterol-->7-Dehydrocholesterol --> vitamin D3 |
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Term
| formation of vitamin D3 from 7-dehydrocholesterol |
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Definition
7-dehydrocholesterol + UVB light --> vitamin D3
rxn occurs in epidermis |
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Term
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Definition
liver enzyme
responsible for D3-BP --> 25-OH D3 (clinically relevant form of vitamin D) |
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Term
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Definition
kidney enzyme
responsible for formation of active vitamin D from 25-OH-D3
25-OH-D3 --> 1,25 (OH)2-D3 active form
PTH mediates its affects through this enzyme (form active vitamin D3).
- FB by product |
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Term
| effects of PTH on Calcium |
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Definition
(cause) low serum Ca
(effect) inc PTH
PTH effects: inc Ca intestinal abs, inc bone resorption, inc Ca kidney reabs |
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Term
| how 1,25 (OH)2 D3 regulates gene expression |
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Definition
| 1,25 (OH)2 D3: VDR (steroid hormone zinc finger receptor):RXR (retinoic acid receptor)--> dimer binds VDRE (vitamin D response element) on specific genes (calcium channel ions and calbindin) |
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Term
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Definition
clinically relevant form of vitamin D
levels used to assess deficiency |
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Term
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Definition
rickets
osteomalacia
Significant prevalence of subclinical vitamin D deficiency in US population, highest among African Americans (42%) – in whites 4.2% |
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Term
| things that inc risk for vitamin D deficiency |
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Definition
Deficiency particular concern …
for persons of color in regions far from equator
breastfed infants receiving little sun exposure
elderly with little sun exposure
excessive use of sunscreens (?) |
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Term
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Definition
PRIMARY: antioxidant for cell membranes particularly PUFA component of phospholipids; scavenger of free radicals & peroxyl radicals
chain breaking antioxidant --> prevents propagation of free radical damage in cell membranes
Other functions include inhibition of protein kinase C; inhibition of platelet aggregation & increased vasodilation |
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Term
| vitamin K (phylloquinone) fcts |
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Definition
PRIMARY: regulation of blood clotting protein synthesis; 7 vitamin K-dependent proteins involved in coagulation
also involved in carboxylation of non-coagulant proteins, including at least 2 for bone development – osteocalcin and matrix GLA protein |
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Term
| K dependent clotting cascade proteins |
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Definition
Factor IX
Factor VII
Factor X
Protein S
Protein C
Protein Z
prothrombin |
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Term
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Definition
uncommon in adults
primary manifestation = bleeding
significant MM cause among breat fed newborns (b/c breast milk low in vitamin K)
associated with hemorrhagic disease of newborn (baby is sterile, does not have intestinal bacteria that make K). Vitamin K prophylaxis given @ birth |
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Term
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Definition
coenzyme (TPP) of active adehyde transfers including oxidative decarboxylation of a-keto acids and transketaolose reaction
required for emtabolism of carbohydrate & branched-chain aa's
possible role in neurotransmission indpt of conezyme fct, possible role in Na conductance at axonal membranes |
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Term
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Definition
coenz (in flavin mononucleotide FMN and flavin adenine dinucleotide FAD) in 1 or 2 electron transfers-redox rxns
reduction of cytochrome P450 (1 e)
succinate dehydrogenase/acylCoA dehydrogenase (2 e)
Fe abs/mobilization thru redox activity |
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Term
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Definition
| Coenzymes – as nicotinamide adenine dinucleotide (NAD & NADP) – in redox reactions, ATP synthesis & ADP-ribose transfer eactions, coenz to dehydrogenases/ADP-ribosyltranferases |
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Term
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Definition
Deficiency disease called pellegra – technically due to deficiency of both niacin and tryptophan
Pellegra observed in populations consuming high proportion of corn in diet; not observed when those same populations also consume animal protein
Niacin present but not bioavailable in corn; treatment with alkali releases niacin – reason pellegra rare in Mexican & Central America populations
4D's: dermatitis, diarrhea, dementia, and death
encephalopathy like Wernicke's, but responds to niacin supplements |
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Term
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Definition
photosensitive dermatitis; symmetrical lesions on parts of body exposed to sun (typically not the face); Casal’s necklace
Etiology of lesions unknown
Advanced pellegra associated with depressive psychosis; very similar presentation to Wernicke-Korsakoff syndrome – headache, depression, insomnia leading to rigidity & paresis of limbs; severe diarrhea may be present |
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Term
| vitamin B6 fct (pyridoxine) |
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Definition
coenzyme: pyridoxal phosphate (PLP) – for transamination reactions, gluconeogenesis, conversion of tryptophan to niacin
Required for erythrocyte transaminases – chronic severe deficiency results in hypochromic, microcytic anemia
Required for synthesis of neurotransmitters, including serotonin & dopamine |
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Term
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Definition
| Functional form is coenzyme A (CoA) |
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Term
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Definition
| Coenzyme for 4 carboxylases involved in intermediary metabolism: AcCoA carboxylase, pyr carboxylase, methylcrotonyl-CoA carboxylase, propionyl-CoA carboxylase |
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Term
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Definition
Tetrahydrofolate (THF) active form of coenzyme
Coenzyme for one-carbon (methyl group) transfer reactions – most significantly purine & pyrimidine synthesis & methylation of transfer RNA
Some anti-proliferative drugs work by blocking folate activity |
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Term
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Definition
Only vitamin with non-organic component – has cobalt atom in center of corrin ring
Coenzyme for on-carbon transfers with 2 enzymes: methionine synthase & methylmalonyl-CoA mutase |
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Term
| relationship btwn folate and B12 |
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Definition
indistinguishable deficiency sx
both required for thymidylate synth (DNA synthesis) |
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Term
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Definition
Vitamin released from foods by gastric pepsin
Parietal cell of stomach secretes glycoprotein called intrinsic factor (IF) required for absorption
Vitamin B12 binds to haptcorrin in stomach
In duodenum, vitamin B12 released from haptocorrin by pancreatic proteases and binds to IF
Vitamin B12-IF complex absorbed in distal ileum by receptor-medicated transport |
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Term
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Definition
Defective DNA & RNA synthesis – decrease in nucleotide & purine synthesis
Megaloblastic anemia – nucleated RBC with dispersed chromatin
Ineffective hematopoiesis results in premature cell death
Symptoms similar to iron deficieny anemia – fatigue, etc; bright red sore tongue may be present
Defective DNA & RNA synthesis
neural tube defects – experimental studies in animals, epidemiologic studies in humans; since 1998 grain products enriched with folate in US
Hyperhomocysteinemia – atherogenic, hypertensive & procoagulant effects; controversy remains over significance for CVD |
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Term
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Definition
Defective DNA & RNA synthesis
Megaloblastic anemia
Hyperhomocysteinemenia
Megaloblastic anemia due to decreased B12 absorption – also called Pernicious Anemia – result of loss of intrinsic factor secretion (due to atrophic gastritis, achlorhydria of ageing, gastric bypass surgery); easily corrected |
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Term
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Definition
major source of folate for body is methyl-THF
methylene THF-->methyl THF is irreversible
methyl THF has metabolic role of methylating homocystein to emthionine. Demthylate via methionine synthase.
B12 deficiency--> methyl THF accumulats, dec THF, dec purine/DNA synth |
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Term
| veganism and B12 deficiency |
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Definition
| low B12 due to lack of bacteria, especially NO animal products |
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Term
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Definition
reversible biologic reductant, coenz for rxns requiring reduced metal ion (ie Fe or Cu)
antioxidant
impt for nt and neuropeptide synth & synth of corticosteroids, aldosterone
Trp hydroxylation
coenzyme
reduces iron to ferrous state in iron storage pathways
regenerates active vitamin E
essential for collagen cross-linking |
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Term
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Definition
Scurvy result of vitamin C deficiency
Cardinal mesenchymal symptoms result from defects in collagen formation
Signs include petechiae, perifollicular hemorrhages, inflamed & bleeding gums, joint effusions, arthralgia, impaired wound healing; depression, weakness
In developed countries relatively rare but can be observed, especially in individuals with poor diets
Neurologic & hormonal signs not observed until very late – brain & adrenal pools relatively protected
bone abnormalities--impaired growth, scorbutic rosary, disturbed ossification |
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Term
| possible vitamin C therapeautic role |
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Definition
| Vitamin C supplementation has been investigated for decreasing risk of cancer, CVD, stroke and cataracts, as well as for boosting the immune system |
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Term
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Definition
Occurs during refeeding of severely undernourished individual; results from rapid expansion of extracellular fluid, increased insulin due to increased carbohydrate intake
Increased carbohydrate intake stimulates rapid glycogen synthesis, depleting plasma phosphorus concentrations necessary for enzymatic reactions; also new tissue development require excess P and other nutrients further depleting plasma
May result in cardiac arrhythmias and sudden death
Not caused solely by rapid drop in phosphorus levels, but a major contributor; potassium is another important factor
refeed slowly, supplement with phosphorus, potassium & other vitamins |
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Term
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Definition
Heme iron (as in hemoglobin) found exclusively in animal foods [as reduced Fe2+]
Non-heme iron found in both animals & plant foods [as both Fe2+ & Fe3+] |
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Term
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Definition
| Absorption in duodenum & proximal jejunum |
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Term
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Definition
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Term
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Definition
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Term
| changes to Fe transport during Fe overload and deficiency |
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Definition
In Fe deficiency – upregulation of transferrin receptor & downregulation of ferritin
In Fe excess – upregulation of ferritin & downregulation of transferrin receptor |
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Term
| changes to Fe transport during Fe overload and deficiency |
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Definition
In Fe deficiency – upregulation of transferrin receptor & downregulation of ferritin
In Fe excess – upregulation of ferritin & downregulation of transferrin receptor |
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Term
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Definition
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Term
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Definition
| hepatocyte Fe storage protein |
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Term
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Definition
Iron-sulfur complexes – part of mitochondrial aconitase (enzyme catalyzes citrate to isocitrate conversion in TCA cycle); cellular energy production via oxidative phosphorylation
Heme-containing proteins (porphyrin ring containing iron atom)
Carries oxygen in hemoglobin & myoglobin
Constituent of peroxidase enzymes – protects from oxidative injury
Active site of cytochromes – enzymes in electron transport chain |
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Term
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Definition
Microcytic, hypochromic anemia: without sufficient iron, hemoglobin synthesis inhibited (at ALA dehydrogenase step) → continued cell division with resultant smaller red cells
Defined as abnormally low concentration of plasma hemoglobin
Primary physical signs - fatigue, low energy, pallor
Assessed through multiple tests – serum hemoglobin, serum iron, transferrin, ferritin, etc.
Anemia associated with impaired cognitive ability, decreased immune responses, decreased work capacity & body temperature regulation
Iron deficiency during pregnancy associated with shortened gestation, preterm birth and low birth weight
Efficiency of iron absorption is increased in deficiency |
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Term
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Definition
Multiple structural functions – zinc fingers regulate folding numerous proteins, loss of protein function occurs when zinc absent; also cell membrane structure, deficiency results in increased vulnerability to oxidation
Component of metal-response element - regulates expression of specific genes including zinc transporters & metallothionein, genes associated with apoptosis & receptor-mediated immunity
Involved in polymerization of tubulin |
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Term
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Definition
patients with acrodermatitis enteropathica (congenital disease)
Clinical signs & symptoms: growth retardation, delayed sexual maturation, hypogonadism & hypospermia (males only), alopecia, epithelial lesions, immune deficiencies, hypoguesia & dysguesia , impaired wound healing
Hormones impacted by deficiency include growth hormone, gonadotrophins, thyroid hormone, corticosteroids, insulin & prostaglandins |
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Term
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Definition
| Essential component of thyroxine, tetraiodothyronine (T4) & triiodothyronine (T3); essential for proper growth & development |
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Term
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Definition
| Goiter development: iodine required for thyroid hormone synthesis, fall in T4 leads to increased thyroid stimulating hormone (TSH) by pituitary, TSH increases uptake of iodine by thyroid, with increased iodine turnover associated with hyperplasia of thyroid follicle cells |
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