Vitamins & Genetics Flashcards
Vitamin A (retinol, retinal, & retinoic acid)
Features
An antioxidant
Retinal pigments (rhodopsin & iodopsin)
Cellular differentiation (pancreatic & mucus cells)
All-trans retinoic acid to treat acute myelocytic leukemia
Retinal-acne
Vitamin Def:
- Nyctalopia (night blindness)
- Xerosis cutis (dry + scaly skin)
- Corneal squamous metaplasia
- Bitot spots (Keratin debris & foamy spots in conjunctiva)
- Keratomalacia (blindness)
- Immunosuppression
Vitamin A deficiency
Vitamin Toxicity:
Nausea
Vomiting
Increased intra corneal pressure (vertigo & blurred vision)
Acute vitamin A toxicity
Vitamin Toxicity:
Alopecia
Cheilosis
Osteoporosis
Hepatic toxicity & enlargement
Dry skin
Arthralgias
Idiopathic intracranial hypertension
Teratogenic effects
Chronic vitamin A toxicity
Vitamin toxicity:
Yellow/orange skin
B-carotene excess
Vitamin D features
- D3 (Cholecalciferol) absorbed through the skin (stratum Basale) via sun
- D2 (Ergocalciferol) plants, fungi, & yeast
Both get converted to 25-OH-D3 (storage form) in liver & 1,25-OH2D3 (active form aka calcitriol)
Vitamin D functions
- Increase intestinal absorption of Ca2+
- Increase bone mineralization (makes Ca2+ binding protein aka osteocalcin on osteoblasts)
- Increase bone reabsorption via RANKL activation to raise osteoblast levels
Vitamin regulation:
High PTH
Low Ca2+
Low PO4^-3
Increased 1,25(OH)2D3 aka active calcitriol its feedback inhibits it’s own production
Vitamin regulation:
High PTH triggers ________ & _____reabsorption in the kidneys
increased Ca2+ & decreased PO4^-3 reabsorption in the distal renal tubules
Vitamin Deficiency:
During first year of life
- Craniotabes
- Frontal bossing
- Square head (excess osteoid)
- Rachitic Rosary (overgrown cartilage & osteoid tissue in costosternal junctions)
Vitamin D deficiency
Vitamin Deficiency:
- Rickettes (Genu varum) in kids
- Osteomalacia, Osteoporosis, & hypocalcemia tetany in adults
Vitamin D deficiency
Vitamins:
- Lack of UVB (sun exposure)
- Mineral oil as a laxative
- Chronic kidney disease
- Advanced liver disease
Causes of vitamin D deficiency
Vitamins:
Hypercalcemia
Hypercalciuria
Low appetite
Stupor
Vitamin D toxicity
Vitamin A
&
B-carotene/retinal absorption
- Vit A & B-Carotene can be turned into one-another & bile helps them be absorbed into the intestine & gets incorporated into chylomicrons to move through lymph
- Apolipoprotein E receptors on liver bring them into hepatocytes to be stored in Ito cells & adipose cells
Vitamin A
&
B-carotene/retinal release
- Stored Vitamin A & B-carotene bind to retinol-binding proteins (RBP) made in the liver before being released into the blood
- Peripheral tissues with RBP-specific receptors binds retinol while the RBP is sent back into the blood
- Within the tissues retinol is oxidized into usable form retinoic acid
Vitamin:
Synthesis of vitamin A
Retinol is oxidized all-trans-retinol which is isomerized into 11-cis-retinol which is covalently associated with 7-transmembrane protein opsin to make rhodopsin
Function of vitamin A:
Cell growth & differentiation
Retinoic acid receptors with retinoic acid forms heterodimers with retinoic x receptors
The RAR/RXR heterodimers bind retinoic acid response elements (RAREs) in regulatory genes for growth factors, tumor suppressors, & secreted proteins
Vitamin deficiency:
Squamous metaplasia (loss of mucus secreting epithelium & pancreatic cells)
Vitamin A deficiency
All-trans retinoic acid has _________ for RAR it induces differentiation of ________ by binding PML-RARa
The highest affinity for RAR & it induces differentiation of promyelocytic leukemia cells by binding PML-RARa
Vitamins:
All-trans Retinoic acid + RXR/RAR + PML means
Activated transcription causing increased differentiation of malignant promyelocytes into short-lived PMN CANCER
Vitamins:
Retinoic acid + RXR/RAR + PML
Block transcription & differentiation of acute promyelocytic leukemia NO CANCER
Vitamin:
Retinoic acid + RXR/RAR
Activates transcription & differentiation into short-lived PMN’s CANCER
Vitamin A:
RXR is activated by _____ which form heterodimers
9-cis-RA
RXR/RAR (Acute promyelocytic leukemia)
RXR/PPARs (High fatty acid oxidation, angiogenesis, & lipolysis)
Vitamin D synthesis
- Absorbed in the gut
- Vitamin D binds alpha globin (Vit D binding protein) & gets moved to the liver
- Vit D is converted to 25-OH-D via 25-Hydroxylases (CYP27AI & other CYPs)
- 25-OH-D is converted into 1,25OH2D3 (aka active form) via 1 alpha hydroxylase in the kidney
Chronic renal disease & vitamin D deficiency is caused by
Secondary hypertension (low GFR)
Causing hyperphosphatemia & low 1,25(OH)2D3 which reduces more PTH secretion causing secondary hyperparathyroidism
Hyperphosphatemia
Hypocalcemia
Hyperparathyroidism
Osteodystrophy
Low vitamin D (1,25(OH)2D3)
Chronic renal disease & vitamin D deficiency
Morphology of vitamin D
- Excess of unmineralized bone matrix
- Overgrown epiphysial cartilage
- Distorted & irregular masses
- Bone deformities
Vitamins:
Tocopherol & Tocotrienol
Vitamin E
Vitamin Deficiency:
- Hemolytic anemia
- Acanthocytosis
- Ophthalmoplegia
- Pigmented retinopathy
- Muscle weakness
- Demyelination of posterior columns & spinocerebellar tracts
(Progressive ataxia, poor proprioception, impaired joint position, & vibration sensation)
Vitamin E deficiency
Vitamin toxicity:
Enterocolitis (Infants)
Increased need for vit K
Patients taking oral anticoagulants have heavy bleeding
Vitamin E toxicity
Used in redox reactions as a cofactor for dehydrogenases (constituent for NAD & NADP) derived from tryptophan
Vitamin B3 Niacin deficiencies, Pellagra