• Thiamine was the first of the water solubleB vitamins to be identified as an essentialnutrient. Chemically, it consists of asubstituted pyrimidine ring (A) and athiazole, connected by a methyl group.The term vitamin B1 encompassesseveral compounds with thiamine-likeeffects.
• Naturally occurring B1 consists mostly ofthiamine phosphates. In pharmaceuticals,water-soluble thiamine derivatives likethiamine hydrochloride or nitrate as wellas lipophilic thiamine analogues likebenfo-thiamine or fursulthiamine are used.
10Absorption and excretionIt is readily absorbed from both small & largeintestine.The capacity of human intestine to absorb thisvitamin is limited to about 5mg per day.Any excess supply of thiamine is excreted inthe urine.
BIOCHEMICAL FUNCTIONS: THIAMINE• TPP [cocaroxylase] being an essentialpart of the decarboxylatingdehydrogenases acts as a cofactor inmany important reactions in carbohydratemetabolism i.e., dehydrogenase [PDH]complex and α-ketoglutaratedehydrogenase [αKGDH] complexi. Oxidative Decarboxylation of α-ketoacids
ii. Conversion of α-Ketoglutarate to succinyl-SCoAiii. TPP acts as coenzyme in reactionscatalyzed by transketolaseiv. Tryptophan metabolism:Tryptophan pyrrolaseTryptophan N-formylkynurenineO2
v. TPP is a coenzyme for mitochondrialbranched chain α-ketoaciddehydrogenases [decarboxylases] whichoxidatively decarboxylate α-ketoacidsformed in the catabolsim of valine, leucineand isoleucline.
v. In the nervous system: TPP is a cofactorfor the synthesis of acetylcholine.vi. TPP also acts as a coenzyme [co-carboxylase] for pyruvate carboxylase inyeast for non-oxidative decaroxylation ofpyruvate to acetaldehyde.
18FunctionsEssential for normal growth and developmentEssential for maintaining nerves in normalconditionNervous tissue – it plays important role in thenormal functioning of the entire nervoussystem.Digestion – it aids in the digestion especiallythat of carbohydrates.
FUNCTIONSEssential for normal functioning of nervesCo-enzymatic activities- carbohydrate,nucleic acid and energy synthesis
DEFICIENCY Beri beriEarliest symptoms:anorexiadyspepsiaheaviness and weakness of legs.calf tenderness
22DeficiencyNervous disorders – when cells cannotmetabolize glucose, it affects the nervoussystem first, since it depends entirely onglucose for its energy requirement. & There ismental depression.
Digestive symptoms- it occurs due todefective hydrochloric acid production in thestomach patient complains of loss of appetite,poor digestion, loss of weight.
24PROLONGED DEFICIENCYBERI BERIa) DRY BERI BERIb) WET BERI BERI..c) INFANTILE BERI BERIOther diseases which can be associated with itarewernickes encephalopathyperipheral neuritiskorsakoff’s psychosis.
25BERI-BERIEarly symptoms: Irritability, fatigue, restlessness,decreased appetite.Later symptoms: tingling numbness in the extremities dyspnoea cyanosis unusual behaviour seizures loss of conscious
26DRY BERI BERIClinical features:- it is peripheral neuropathy. In long standing cases, there is degenerationand demyelination of both sensory & motornerveINFANTILE BERI BERI Vomiting Weight loss Convulsions
Wet beri beri Dry Beri beri Oedema of legs, face Progressive muscle weaknes andtrunk and serous cavities. disability Calf muscles are swollen and tender Neurological manifestations Palpitation and breathlessness Low diastolic BP, high systolic. Fast pulse Heart becomes weakerand patient dies of heart failure
28Wet beri beriIt is marked by cardiac dilation with four chamberenlargement, pallor and flabbiness ofmyocardium.Etiology :-Diet Alcoholics- interferes with intestinal absorptionof thiamine
Infantile Beri beri Infants born to mother with low thiamine intheir breast milk. Restlessness and sleeplessness Anorexia, vomiting and breathlessness cardiac dilatation and failure. Sudden death if not treated urgently withthiamine.
36Oral manifestationThere is hypersensitivity of oral mucosaPain in tongue, teeth, jaw, and face
37Pathogenesis-DeficiencyIncomplete metabolism of glucoseAccumulation of pyruvic acid & lactic acid intissue & body fluidDilation of peripheral blood vesselsFluid may leak out through capillaries,producing edemaHigh cardiac output, heart dilation.
38ManagementComplete restThiamine 50mg IM for 3 days then 10mg 3times daily by oral route. Infantile beriberi is treated via mothers milk.The mother should receive 10,000mcg twicedaily, in addition infant should be giventhiamine in doses of 10,000 to 20,000 mcg IMonce in a day for 3 days