Nutrition Flashcards
Cofactor for methionine synthase
B12
Sources of B12
Animal products
When does vitamin B12 deficiency develops
After 4 to 5 years of absent intake
Subacute combined degeneration is due to deficiency of what vitamin
B12
Vitamin B1 (thiamine) is a cofactor for what type of enzymes
Dehydrogenases
- Pyruvate dehydrogenase (glycolysis-TCA cycle)
- alpha-ketoglutarate dehydrogenase (TCA cycle)
- Branched-chain ketoacid dehydrogenase (metabolism of valine, leucine, and isoleucine)
- Transketolase (HMP shunt)
Diseases caused by vitamin B1 deficiency
- Wernicke-Korsakoff syndrome: triad of ataxia, nystagmus, and ophthalmoplegia (Wernicke) with confabulation (korsakoff)
- Dry beri-beri: polineuritis, SYMMETRICAL muscle wasting
- Wet beri-beri: high-output cardiac failure (dilated cardiomyopathy), edema
Part of the CNS damaged by vitamin B1 deficiency
- MAMMILLARY BODIES
2. Medial dorsal nucleus of the thalamus
Laboratory diagnosis of vitamin B1 deficiency
Increase in RBC transketolase activity following vitamin B1 administration
Niacin is synthesized from which aminoacid
Tryptophan
Pathogenesis of Hartnup disease
Deficiency of neutral aminoacid (tryptophan) transporters in proximal renal tubular cells and on enterocytes, leading to neutral aminoaciduria and decreased absorption from the gut
*Can lead to pellagra-like symptoms
4 D’s of pellagra
- Diarrhea
- Dermatitis (C3/C4 circumferential “broad collar” rash - Casal necklace, and hyperpigmentation of sun-exposed limbs)
- Dementia
- Death
Pyridoxine (vitamin B6) is a cofactor for…
- Aminotransferase reactions (ALT and AST)
- Delta aminolevulinate synthase (rate-limiting enzyme in heme synthesis)
- Glycogen phosphorylase
- Synthesis of cystathionine
Most common cause of pyridoxine deficiency
Isoniazid
Clinical manifestations of pyridoxine deficiency
- SIDEROBLASTIC ANEMIA
- PERIPHERAL NEUROPATHY
- Cheilosis/stomatitis
- Convulsions
Function of biotin (vitamin B7)
Cofactor for carboxylation enzymes (adding of a 1-carbon group)
- Pyruvate carboxylase (pyruvate to oxaloacetate)
- Acetyl-CoA carboxylase (acetyl-CoA to malonyl-CoA)
- Propionyl-CoA carboxylase (propionyl-CoA to methylmalonyl-CoA)
Folate stores in the body can cover its need for how long
3 to 4 months
Most important clinical manifestations of folic acid deficiency
- Macrocytic megaloblastic anemia (with hypersegmented neutrophils)
- Homocysteinemia
- Neural tube defects (pregnant women)
Common signs and symptoms to all B-complex deficiencies
- Dermatitis
- Glossitis
- Diarrhea
Diseases that can be treated with vitamin A
- Measles
* Acute promyelocytic leukemia (all-trans retinoic acid)
Food sources of vitamin A
Liver and leafy vegetables
Vitamin A derivative used to treat severe cystic acne
Isotretinoin
Signs and symptoms of vitamin A deficiency
- Nyctalopia (earliest manifestation)
- Xerosis cutis
- Keratomalacia (metaplasia to stratified keratinizing squamous epithelium)
- Bitot spots
- Immunosuppression
Water soluble vitamin that is teratogenic
Vitamin A
Signs and symptoms of B2 deficiency
- Cheilosis
- Corneal vascularization
- Magenta-colored tongue
Vitamin that can be derived from the aminoacid tryptophan
B3
*Its synthesis requires B2 and B6
Pharmacologic use of niacin
Dyslipidemia
*Lowers VLDL and raises levels of HDL
Common causes of niacin deficiency
- Harnup disease
- Malignant carcinoid syndrome (increased tryptophan metabolism)
- Isoniazid (decreased B6)
Drug that can be taken to prevent facial flushing caused by niacin
Aspirin
*In this case, facial flushing is caused by prostaglandins, not by histamine
Ingestion of what type of food can lead to biotin deficiency
Raw egg whites (they contain avidin, which binds to biotin)
Regions of the spinal cord affected by subacute combined degeneration (vitamin B12 deficiency)
- Dorsal columns
- Lateral corticospinal tracts
- Spinocerebelar tracts
Vitamin C facilitates absorption of which element
Iron, by reducing it to its Fe2+ state
Neurotransmitter synthesis enzyme that requires vitamin C as a cofactor
Dopamine beta hydroxylase
*Converts dopamine to NE
Signs and symptoms of scurvy
- Swollen gums
- Brusing
- Petechiae
- Hemarthrosis
- Anemia
- Poor wound healing
- Perifollicular and subperiosteal hemorrhages
- Corkscrew hair
Enzyme in charge of activating vitamin K to its reduced form
Epoxide reductase
Gamma carboxylation of glutamic acid resiudes on blood clotting proteins needs which lipid-soluble vitamin
Vitamin K
Clotting factors that need vitamin K for their synthesis
Factors 2, 7, 9, 10, and proteins C and S
Molecule deficiency that leads to Kwashiorkor
Protein deficiency
Signs and symptoms of Kwashiorkor
“Kwashiorkor results from protein-deficient MEALS”
- Malnutrition
- Edema
- Anemia
- Liver (fatty)
- Skin lesions (hyperkeratosis/hyperpigmentation)
Define the “flag sign”
Seen in Kwashiorkor, when hair color is restored with periods of adequate dietary intake
Pathogenesis of marasmus
Malnutririon not causing edema, diet is deficient in calories but no nutrients are entirely absent
*Marasmus results in muscle wasting
Limiting reagent of alcohol metabolism
NAD+
Functions of vitamin D in GI tract, kidney, and bone
- GI: induces synthesis of calcium binding proteins and increases phosphate absorption
- Kidney: stimulates absorption of calcium and secretion of phosphate
- Bone: activates osteoclasts and induces bone resorption
Allosteric activator of pyruvate kinase
Fructose-1,6-biphosphate
Enzyme inhibited by warfarin
Vitamin K epoxide reductase
Function of vitamin K epoxide reductase
It transforms vitamin K to its active form after it has been used by the gamma glutamyl carboxylase to carboxylate clotting factors
