HNF 462 1st Edition Lecture 3Outline of Last Lecture I. Antioxidant ActivityII. Functions in Health and Diseasesa. Cancerb. Coldc. CVDIII. Excretiona. Formation of kidney stonesIV. RDAV. Measurementsa. Physical Methodb. Chemical MethodOutline of Current LectureI. Deficiencya. Beriberi b. MeasurementsII. Discovery and IsolationIII. FunctionsIV. Food Sources and StabilityV. Digestion, Absorption, and TransportationVI. ExcretionVII. RDACurrent Lecture: 1. Deficienciesa. Beriberi: deficiency syndrome—three typesi. Dry: Primarily in older adults, resulting in muscle weakness/wasting in lower extremities and peripheral neuropathy (because peripheral neurons and sensories can’t sense feelings)ii. Wet: Enlarged heart, rapid heart beat, peripheral edema (body fluid accumulation), peripheral neuropathyiii. Acute/Infantile: Anorexia, vomiting, lactic acidosis (accumulation of lactic acid in the blood), altered heart rate, and enlarged heartThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.b. Signs of deficiencies are loss of appetite/weight loss, cardiovascular abnormalities, and neurological symptomsi. People at risk are congestive heart failure patients, alcoholics, AIDS patients, and the elderlyc. Measurement i. Measured in urine: < 40 ug signifies deficiencyii. Measured creatinine in the urine (proportional to amount of thiamin in the muscles): <27 ug/day signifies deficiencyiii. Measured transketolase activity measured in red blood cells: Increase >25% signifies deficiency2. Discovery and Isolationa. First discovered in 1800s by Christiaan Eijkman when trying to find cure to beriberii. First time white and brown rice were found to be different (brown rice has bran layer, which contains thiamin)b. First isolated in 1926: excellent success to cure beriberi 3. Functionsa. Coenzyme for oxidative decarboxylationi. Pyruvate Dehydrogenase Complex1. Vitamin B1 functions to temporarily hold the acetyl group of pyruvate, then it is added to lipoamide to make Acetyl CoAii. Alpha-ketoglutarate Dehydrogenase Complex1. Similar mechanism to the decarboxylation of pyruvate2. Decarboxylates alpha-ketoglutarate dehydrogenase complex and forms succinyl-CoAiii. Transketolase1. Vitamin B1 acts as a coenzyme to transketolase for the generation of NADPHiv. Branched-Chain Alpha-Keto Dehydrogenase Complex1. Similar mechanism to decarboxylation of pyruvate2. Oxidative process that requires thiamin as TDP: decarboxylates branched-chain amino acids (leucine, isoleucine, and valine) in order to oxide/metabolize them4. Food Sources and Stabilitya. Widely available from meat (especially pork), legumes, and whole grains (containthe bran layer)i. Plant sources contain unphosphorylated thiaminii. Animal sources contain phosphorylated forms (usually TDP/TPP—two phosphate groups, and rarely TMP—one phosphate group)b. Destroyed easily by alkaline environment, heat, and cooking in water5. Digestion, Absorption, and Transportationa. Digestioni. Digested in the phosphorylated forms.ii. Phophatases are responsible for digesting, and then removing the phosphate groupsb. Absorbed in the free formi. High intakes: absorbed by passive diffusionii. Low intakes: absorbed by active Na-dependent transport; a co-transporting system (thiamin in, and hydrogen out)iii. Cellular Absorption takes place by both diffusion and active transport, in both free and TMP formsiv. Absorption Inhibitors: Thiaminases, tannic and caffeic acids, and ethanolc. Transported in the bloodi. Free form bounded to albumin (protein)ii. Unbounded TMP6. Excretiona. Mostly in free formb. Decreased thiamin intake = decreased thiamin excretion7. RDAa. Men: 1.2 mg/dayb. Women: 1.1 mg/dayc. Pregnancy and Lactation: 1.4
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