Thiamine also

Beriberi, a neurologic and cardiovascular disorder, is caused by a dietary deficiency of thiamine (also called vitamin B ). The disease has been and continues to be a serious health problem in the Far East because rice, the... 

Thiamine, also known as vitamin Bi, forms the coenzyme thiamine pyrophosphate (TPP). It is required for the essential decarboxylation reactions catalyzed by the pyruvate and 2-oxoglutarate complexes. 

Beriberi, a neurologic and cardiovascular disorder, is caused by adi etary deficiency of thiamine (also called vitamin B,). The disease has been and continues to be a serious health problem in the Far East because rice, the major food, has a rather low content of thiamine. This deficiency is partly ameliorated if the whole rice grain is soaked in water before milling some of the thiamine in the husk then leaches into the rice kernel. The problem is exacerbated if the rice is polished, because only the outer layer contains significant amounts ot thiamine. Beriberi is also occasionally seen in alcoholics who are severely malnourished and thus thiamine deficient. The disease is characterized by neurologic and cardiac symptoms. Damage to the peripheral nervous system is expressed as pain in the limbs, weakness of the musculature, and distorted skin sensation. The heart may be enlarged and the cardiac output inadequate. 

The answer is b. (Murray, pp 627-661. Scriver, pp 3897-3964. Sack, pp 121-138. Wilson, pp 287-320.) Nicotinamide adenine dinucleotide (NAD+) is the functional coenzyme derivative of niacin. It is the major electron acceptor in the oxidation of molecules, generating NADH, which is the major electron donor for reduction reactions. Thiamine (also known as vitamin Bi) occurs functionally as thiamine pyrophosphate and is a coenzyme for enzymes such as pyruvate dehydrogenase. Riboflavin (vitamin B2) functions in the coenzyme forms of flavin mononucleotide (FMN) or flavin adenine dinucleotide (FAD). When concentrated, both have a yellow color due to the riboflavin they contain. Both function as prosthetic groups of oxidation-reduction enzymes or flavoproteins. Flavoproteins are active in selected oxidation reactions and in electron transport, but they do not have the ubiquitous role of NAD+. 

Thiamine, also known as vitamin B, is fairly ubiquitous. Thiamine deficiency is uncommon except in alcoholics as a result of nutritional deficiencies and malabsorption. The classic clinical triad of dementia, ataxia (difficulty with walking), and eye findings may be seen, but more commonly, only forgetfulness is noted. Sometimes, thiamine deficiency can lead to vague symptoms such as leg numbness or tingling. Because thiamine is water soluble, it can be added to intravenous fluids and administered in that way. Other manifestations include beri beri, which is cardiac involvement leading to a high cardiac output, and vasodilation. Affected patients often feel warm and flushed, and they can have heart failure. 

Thiamine, also known as vitamin B, is required in the diet of aU animals. Its biologically active form is the coenz)une thiamine p)rrophosphate. This coenzyme is required for many decarboxylation reactions, including the decarboxylation of... 

Beriberi is a neurological and cardiovascular disorder that is caused by a deficiency of thiamine (also called vitamin Bj). It has been a serious health problem in Asia and continues to be in those places where rice is the main staple food. The problem is exacerbated if the rice is dehusked (polished) because only the outer layers of the seeds contain appreciable amounts of thiamine. Beriberi also occurs in some malnourished chronic alcoholics, so to avoid this problem in some countries certain alcohol-containing drinks are fortified with thiamine. Beriberi is characterized by pain in the limbs, weak muscles, abnormal skin sensation, and an enlarged heart with inadequate cardiac output. Which biochemical processes are affected by thiamine deficiency ... 

PAM Cl is rapidly and almost completely excreted unchanged by the kidneys 80% to 90% of an intramuscular or intravenous dose is excreted in 3 hours,146 probably by an active tubular excretory mechanism (its renal clearance is close to that of p-aminohippurate147), with a half-time of about 90 minutes.146 Both clearance and amount excreted are decreased by heat, exercise, or both.148 Thiamine also decreases excretion (presumably by blocking tubular excretion), prolongs the plasma half-life, and increases the plasma concentration for the duration of thiamine activity147 150 some151 question the therapeutic benefit of thiamine, however. 

I. Pharmacology. Thiamine (vitamin B ) is a water-soluble vitamin that acts as an essential cofactor for various pathways of carbohydrate metabolism. Thiamine also acts as a cofactor in the metabolism of glyoxylic acid (produced in ethylene glycol intoxication). Thiamine deficiency may result in beriberi and Wemicke-Korsakoff syndrome. Thiamine is rapidly absorbed after oral, intramuscular, or intravenous administration. However, parenteral administration is recommended for initial management of thiamine deficiency syndromes. 

Thiamine alters the genetic response to cell injury to protect cells. TPP inhibits p53 DNA binding, and the thiamine inhibits intracellular p53 activity. Thiamine affects two p53-regulated cellular responses to ionizing radiation rereplication and apoptosis (McLure et al., 2004). Thiamine also interacts with NFkappaB. Diabetes induces NFkappaB and this induction is diminished by thiamine (Hammes et al., 2003). 

The investigation of characteristic flavors associated with cooked meats has been the subject of much research over the past four decades but, although compounds with "meaty" aromas had been synthesized, compounds with such characteristics were not found in cooked meats until recently (1). In the search for compounds with characteristic aromas it was found that furans and thiophenes with a thiol group in the 3-position possessed meat-like aromas (2). The corresponding disulfides formed by oxidation of furan and thiophene thiols were also found to have meat-like characteristics, and exceptionally low odor threshold values (3). A number of such compounds are formed in heated model systems containing hydrogen sulfide or cysteine and pentoses or other sources of carbonyl compounds (4,5), The thermal degradation of thiamine also produces 2-methyl-3-fiiranthiol and a number of sulfides and disulfides (6J). 

The thiazole ring occurs in thiamin (vitamin Bi), a coenzyme required for certain metabolic processes and hence essential to life (thiamin also contains a pyrimidine ring). In its reduced form, the tetrahydrothiazole ring appears in penicillins, which are important antibiotics. 

Raw or gently pasteurised milk (e.g. for 10 seconds at 73 °C) has a fine characteristic odour and sweet taste. Typical components present in low concentrations are dimethylsulfide, biacetyl, 2-methylbutan-l-ol, (Z)-hept-4-enal and ( )-non-2-enal. Milk pasteurised at higher temperatures and Ultra High Temperature (UHT) milk present the so-called cooked flavour, the appearance of which is the first measurable manifestation of the chemical changes that occur in heated milk. The substances responsible for the cooked off-flavour are sulfane and other sulfur compounds. Of particular importance are dimethylsulfide, dimethyldisulfide and dimethyltrisullide that are produced from proteins contained in the membranes of fat particles and from thiamine. Also relevant are alkane-2-ones (methylketones) generated by thermal decarboxylation of P-oxocarboxylic acids (mainly hexane-2-one, heptane-2-one and nonane-2-one), y-lactones and 5-lactones produced by dehydration of y- and 5-hydroxycarboxylic acids (mainly 8-decalactone and y- and 8-dodecalactones). Important carbonyl compounds include biacetyl, hexanal, 3-methylbutanal, (Z)-hept-4-enal and ( )-non-2-enal. In the more intensive thermal treatment of milk (sterilisation), products of the Maillard reaction play a role, such as maltol and isomaltol, 5-hydroxymethylfuran-2-carbaldehyde, 4-hydroxy-2,5-dimethyl-2 f-furan-3-one (furaneol) and 2,5-dimethylpyrazine. 

Lamb is important in the diet, not for its appetite appeal alone, but for the essential food nutrients that it contains. It is an excellent source of high-quality protein for muscle building and body maintenance. In most cuts of lamb, the fat may be easily separated from the lean hence, the calories can be adjusted to desired levels. Lamb is one of the best sources of iron, needed for hemoglobin formation and it is rich in phosphorus, needed for bones and teeth. It is also an excellent source of vitamin B-12, vitamin B-6, biotin, niacin, pantothenic acid, and thiamin. Also, lamb muscle is easily digested, so it is included in the diet of both the young and aged. 

Brazll nuts are similar In nutritive value to almonds, except that they contain more calories, essential fatty acids, phosphorus, and thiamin, Also, they contain less rralcium, iron, magnssiun, riboflavin, and niacin. 

Thiamin, also called aneurin and vitamin Bi, is present in most plant and animal tissues. A pyrimidine ring and a thiazole moiety linked by a methylene bridge are... 

Another natural carbon-carbon bond-forming process that has been adapted for use by synthetic chemists involves thiamine, or vitamin Bi, shown on p. 1058. Thiamine plays an essential role in several biochemical processes, including the biosynthesis of sugars, as we shall see in Chapter 24. Real Life 23-2 describes how thiamine also mediates sugar metabolism by converting pyruvic acid, a product of sugar metabolism, into acetyl CoA (Section 19-13). The relevant carbon-carbon bond-forming process makes use of a new kind of nucleophile derived from aldehydes and ketones, an acyl anion equivalent. 

Beriberi is caused by a deficiency of thiamin (also called thiamine, aneurin(e), and vitamin Bj). Classic overt thiamin deficiency causes cardiovascular, cerebral, and peripheral neurological impairment and lactic acidosis. The disease emerged in epidemic proportions at the end of the nineteenth century in Asian and Southeast Asian countries. Its appearance coincided with the introduction of the roller mills that enabled white rice to be produced at a price that poor people could afford. Unfortunately, milled rice is particularly poor in thiamin thus, for people for whom food was almost entirely rice, there was a high risk of deficiency and mortality from beriberi. Outbreaks of acute cardiac beriberi still occur, but usually among people who live under restricted conditions. The major concern today is subclinical deficiencies in patients with trauma or among the elderly. There is also a particular form of clinical beriberi that occurs in patients who abuse alcohol, known as the Wer-nicke-Korsakoff syndrome. Subclinical deficiency may be revealed by reduced blood and urinary thiamin levels, elevated blood pyruvate/lactate concentrations and a-ketoglutarate activity, and decreased erythrocyte transketolase (ETKL) activity. Currently, the in vitro stimulation of ETKL activity by thiamin diphosphate (TDP) is the most useful functional test of thiamin status where an acute deficiency state may have occurred. The stimulation is measured as the TDP effect. 

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