Vitamin Deficiency Flashcards
What are the sources of thiamin
Plant : yeast green vegetables and unrefined grains
Animal: liver. Kidney,milk, and eggs
What is the importance of thiamine
It forms the coenzyme thiamine pyrophosphate by ATP dependent enzymes in liver and brain
What are the reactions requiring TPP
1-oxidative decarboxylation of
Pyruvate —-> acetyl coa
&-ketoglutarate ——-> succinyl coA
Branched chain &-Keri acid dehydrogenase of branched chain amino acid catabolism
2-transketolase in HMP pathway
3-decarboxylation of pyruvate in yeast
What does deficiency of thiamine cause
Deficient of pyruvate and ketoglutarate dehydrogenase resulting in decrease production of ATP , impaired cellular function particularly in nervous tissues
What is the biochemical detection of thiamine deficiency
1-dietary history of low thiamine and clinical
2-blood thiamine
3-eryrlthrocyte transketilase activity
4-thiamine pyrophispahate activity
5- estimation of pyruvate and lactate levels
What are the beriberi and wernicks-korsakoff
Making nerve degeneration of legs then arm in areas wheee polished rice is the major component in diet
Seen in alcoholics due to dietary insufficiency or impaired intestinal absorption of the vitamin
What are the consequences if PDH deficiency
It doesn’t proceed too produce acetyl coA , it is shunted to produce lactic acid and alanine
The deficiency limits production of citrate
The citric acid cycle cannot proceed.
Alternate metabolic pathways are stimulated to produce acetyl coA
However an energy deficit remains
What is the clinical picture of PDH deficiency
Lactic acidosis
Hypotonia and poor feeding
Lethargy and structural abnormalities in the brain
May develop seizures and neuropathological spasm
Usually progress to mental retardation, microcephaly, blindness and spasticity
What is the treatment of PDH
Dietary restriction of carbohydrates
Correction of acidosis
What are the different structures of niacin
Niacin: contains a pyridine ring
Nicotinic acid: pyridine-3-carbixylic acid
Nicotinamide: delaminated in the body to give niacin
What are the sources of niacin
1-same as vitamin b1
2-can be synthesized from tryptophan in human body
60mg—>1 mg nicotininc acid
Vit b6 is required in this process
What are the functions of niacin
It forms 2 coenzymes act as a hydrogen carriers for oxidoreductase
NAD: nicotinamide adenine dinucleotide
NADP: nicotinamide adenine dinucleotide phosphate
What are the causes of deficiency of niacin
1- a diet poor in niacin and tryptophan Ex:corn
2-defective absorption: hartnup disease in which tryptophan absorption is impaired
3-vit b6 deficiency which is needed for niacin synthesis from tryptophan
4- excessive utilization of tryptophan as in carcinoid tumor (60% of tryptophan
Is converted to seretonin leading to decrease production of nicotinic acid
What are the symptoms and treatment of pallegra?
1-dermatitis
2diarrhea
3-dementia
4-death
Treat the cause
Nicotininc acid supplement
What is the structure of folic acid?
Petridine ring+poly glutamic amino acid 2-7+ PABA
