Chapter 10: Vitamins Flashcards
What type of vitamins, (lipid or water soluble) are precursors for coenzymes?
water-soluble
What are enzymes that are dependent on biotin?
- pyruvate carboxylase
- Acetyl CoA carboxylase
- propionyl CoA carboxylase
What are some metabolic pathways that utilize biotin?
- gluconeogenesis
- fatty acid synthesis
- odd-carbon fatty acids, Val, Met, Ile, Thr
What is the most common cause although rare, of biotin deficiency?
excessive consumption of raw eggs (contain avidin, a biotin-binding protein) also, biotinidase deficiency
Some S/E of having biotin deficiency?
alopecia (hair loss), bowel inflammation, muscle pain
Another name for B1?
Thiamine
What are the enzymes that utilize thamine?
- pyruvate dehydrogenase
- α-ketoglutarate dehydrogenase
- Transketolase
- Branched chain ketoacid dehydrogenase
What are some metabolic pathways that utilize thiamine?
- PDH
- TCA cycle
- HMP shunt
- Metabolism of valine, isoleucine, and leucine
What are some causes of thiamine deficiency?
alcoholism (alcohol interferes with absorption)
What are some signs and symptoms of thiamine deficiency?
Wernicke (ataxia, nystagmus, ophthal-moplegia)
Korsakoff (confabulation, psychosis)
Wet beri-beri (high output cardiac failure, fluid retention, vascular leak and dry beri-beri (peripheral neuropathy)
What are important enzymes that utilize niacin?
dehydrogenases
Niacin is a major component of what two coenzymes?
NAD(H)
NADP(H)
What metabolic pathways utilize niacin?
many
What are the side effects of niacin deficiency?
Pellagra: diarrhea, dementia, dermatitis, and if not treated death
Pellagra may also be related to what important deficiency?
deficiency of tryptophan in areas where there are lots mostly corn diet, corn is low in tryptophan which supplies a portion of the niacin requirement
What are important enzymes that utilize folic acid?
thymidylate synthase
What is THF?
Tetrahydrofolic acid is a folic acid derivative that is produced from dihydrofolic acid after conversion by dihydrofolate reductase.
What are metabolic pathways that folic acid is utilized in?
thymidine (pyrimidine) synthesis
purine synthesis
What is the most common cause of folic acid deficiency?
alcoholism and pregnancy (body stores depleted in 3 months), hemodialysis
What are some symptoms of folic acid deficiency?
homocystinemia with risk of deep vein thrombosis and atherosclerosis
megaloblastic (macrocytic anemia)
Deficiency in early pregnancy causes NTD in fetus
What is another name for B12?
cyanocobalamin
What are enzymes that require B12?
homocysteine methyltransferase
methylmalonyl CoA mutase
What pathways utilize B12
methionine, SAM
Odd-carbon fatty acids, Val, Met, Ile, Thr
What are the most common causes of B12 deficiency?
pernicious anemia
aging especially with poor nutrition, bacterial overgrowth of terminal ileum, resection of the terminal ileum secondary to Crohn disease, chronic pancreatitis, and rarely vegans, or infection with D latum (Diphyllobothrium latum)
What are some signs and symptoms of B12 deficiency?
megaloblastic (macrocytic) anemia
progressive peripheral neuropathy
What is another name for vitamin B6?
pyridoxine
What is Pyridoxal P? What does it stand for?
One of the active forms of vitamin B6
Pyridoxal 5’ phosphate
What are enzymes that utilize B2?
dehydrogenases
What is another name for B2?
riboflavin
What coenzyme does riboflavin create?
FAD(H2)
What are some S/E of riboflavin deficiency?
corneal neovascularization
cheilosis or stomatitis (cracking or scaling of lip borders and corners of the mouth)
magenta colored tongue.
What are some enzymes that utilize ascorbate (C)?
prolyl and lysyl hydroxylases
dopamine hydroxylase
What are some metabolic pathways that require ascorbate?
collagen synthesis
catecholamine synthesis
absorption of iron in GI tract
What is the most common cause of vit. C deficiency?
diet deficient in citrus fruits and green veggies
What are the signs and symptoms of ascorbate deficiency?
scurvy: poor wound healing, easy bruising, bleeding gums, increased bleeding time, painful glossitis, anemia
What are the enzymes that require pantothenic acid CoA?
fatty acid synthase
fatty acyl CoA synthetase
pyruvate dehydrogenase
α-ketoglutarate dehydrogenase
What are the important metabolic pathways that utilize pantothenic acid?
fatty acid metabolism
PDH
TCA cycle
Is a deficiency of pantothenic acid common?
rare
What is infantile scurvy?
when infants are 2-10 months of age who are bottle-fed with formula that is overheated for pasteurization and not supplemented with Vit. C pithed frog position
bleeding occurs same as adults but gum bleeding is not a common feature
What is renal osteodystrophy?
a bone disease that occurs in adults and children with chronic kidney disease
What are some symptoms of Vitamin D deficiency?
bone demineralization
rickets (children)
osteomalacia (adults)
What are symptoms of Vitamin A deficiency?
- night blindness
- keratinized squamous epithelia
- xeropthalmia, bitot spots
- keratomalacia, blindness
- follicular hyperkaratosis
- alopecia
Most common cause of vitamin D deficiency?
insufficient sunlight, inadequate fortified foods (milk), or end-stage renal disease (renal osteodystrophy)
What are some causes of Vit. A deficiency?
fat malabsorption or fat-free diet
What is vitamin E deficiency caused by?
caused by fat malabsorption or premature birth
What are other names for Vit A? (as a whole not active forms)
carotene
Which type of vitamin A is important in rod and cone cells for vision?
retinal
Which type of vitamin A is important as a growth regulator especially in epithelium?
retinoic acid and retinol
Other names for Vitamin K?
Menaquinone, bacteria; phytoquinone, plants
What are the important functions of vitamin K?
carboxylation of glutamic acid residues in many Ca2+ binding proteins, importantly coagulation factors II, VII, IX, and X as well as protein C and protein S
What are the important functions of Vitamin E
antioxidant; protect membrane lipids from peroxidation
What are other names for vitamin E?
α-tocopherol
1-α hydroxylase important final rate limiting step in conversion of what substrate to what product?
vitamin D to 1,25-DHCC (dihydroxycholecalciferol or calcitriol)
What are other sources with which to get vit. D if there is insufficient exposure to UV light?
Vit. D3 is found in saltwater fish (salmon) and egg yolks
Describe or draw out the Steps in the synthesis and activation of vitamin D
Draw and explain diagram
Genetic deficiencies or patients with end stage renal disease have impaired 1α hydroxylation defects patient must be given 1,25-DHCC. List some of these types of patients.
End-stage renal disease secondary to DM
Fanconi renal syndrome (renal proximal tubule defect)
Genetic deficiency of the 1α hydroxylase (vit D resistant rickets)
What can excess vit D cause?
can promote intestinal absorption of Ca2+ and phosphate also bone resorption leading to hypercalcemia
What are some early signs of Vit D toxicity besides bone related conditions?
polyuria, polydipsia, and nocturia
What does deficiency of vit. D after epiphyseal fusion lead to?
osteomalacia
Vitamin A is associated with what two important functions?
maintenance of healthy epithelium and vision
Describe the structures of retinol, retinoic acid, and retinal?
retinol has a hydroxyl group at C-1
retinoic acid: a carboxyl group at C-1
retinal: an aldehyde group at C-1
What are the main functions of retinol and retinoic acid?
required for the growth, differentiation, and maintenance of epithelial cells
What is a major use for isotretinoin? Which form of vit A is it?
a form of retinoic acid that is used in the treatment of acne
What are some major teratogenic effects of using isotretinoin?
malformations of the craniofacial, cardiac, thymic, and CNS structures)
