Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “THIAMINE”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3Linked to original sources
PubMed1987

Effects of supplement sulfate (Dynamate) and thiamin-HCl on passage of thiamin to the duodenum and site of digestion in steers.

Effects of dietary supplementation of thiamin-HCl (1 g daily) and a feed grade double sulfate of magnesium and potassium (Dynamate, added at 1.8% of diet dry matter; referred to as sulfate) on ruminal passage of thiamin and site of digestion in dairy steers (464 kg initial weight) fed a 77% concentrate diet were determined in a 4 X 4 Latin square experiment. Sulfate supplementation tended to reduce duodenal thiamin flow with (P less than .08) and without (P greater than .10) added thiamin. Supplementation with thiamin alone decreased ruminal disappearance of fed organic matter and nitrogen (P less than .03) and total tract disappearance of starch (P less than .06) and nitrogen (P less than .02), and increased ruminal microbial efficiency (P less than .04). Sulfate addition to the high thiamin diet alleviated these effects but depressed microbial efficiency (P less than .05). Sulfate included in the diet without added thiamin affected plasma thiamin positively, whereas sulfate added to the diet with supplemental thiamin changed plasma thiamin negatively (interaction, P less than .06). In conclusion, a marked depression of ruminal digestion induced by dietary thiamin-HCl supplementation disappeared upon dietary addition of sulfate and sulfate depressed the quantity of thiamin passing from the rumen. Because preventing thiamin deficiency and optimizing site of digestion in feedlot cattle are desired, these changes deserve further study.

Animals↗
PubMed1985

Bioavailability for rats of thiamin in whole wheat and thiamin-restored white bread.

The relative biological value of thiamin in leavened bread (whole wheat and thiamin-restored white) and thiamin mononitrate was examined by using thiamin-deficient rats as the test model. Erythrocyte transketolase (ETK) activities and liver thiamin content responded positively to graded but suboptimal levels of dietary thiamin in these rats. Biological values were calculated (slope ratio assay) by using these response parameters, which may depict the body's thiamin status, at least in the deficient rats. Compared to thiamin in thiamin mononitrate (100%), the biological value of thiamin in breads measured 88% (white bread) and 91% (whole wheat bread) based on ETK activity and 68% (white bread) and 75% (whole wheat bread) based on liver thiamin response. Thus, diets high in fermented cereal foods (thiamin enriched or not) may require a generous allowance of thiamin to compensate for reduced biological value.

Animal Nutritional Physiological Phenomena↗
PubMed1999

Defective high-affinity thiamine transporter leads to cell death in thiamine-responsive megaloblastic anemia syndrome fibroblasts.

We have investigated the cellular pathology of the syndrome called thiamine-responsive megaloblastic anemia (TRMA) with diabetes and deafness. Cultured diploid fibroblasts were grown in thiamine-free medium and dialyzed serum. Normal fibroblasts survived indefinitely without supplemental thiamine, whereas patient cells died in 5-14 days (mean 9.5 days), and heterozygous cells survived for more than 30 days. TRMA fibroblasts were rescued from death with 10-30 nM thiamine (in the range of normal plasma thiamine concentrations). Positive terminal deoxynucleotide transferase-mediated dUTP nick end-labeling (TUNEL) staining suggested that cell death was due to apoptosis. We assessed cellular uptake of [3H]thiamine at submicromolar concentrations. Normal fibroblasts exhibited saturable, high-affinity thiamine uptake (Km 400-550 nM; Vmax 11 pmol/min/10(6) cells) in addition to a low-affinity unsaturable component. Mutant cells lacked detectable high-affinity uptake. At 30 nM thiamine, the rate of uptake of thiamine by TRMA fibroblasts was 10-fold less than that of wild-type, and cells from obligate heterozygotes had an intermediate phenotype. Transfection of TRMA fibroblasts with the yeast thiamine transporter gene THI10 prevented cell death when cells were grown in the absence of supplemental thiamine. We therefore propose that the primary abnormality in TRMA is absence of a high-affinity thiamine transporter and that low intracellular thiamine concentrations in the mutant cells cause biochemical abnormalities that lead to apoptotic cell death.

Anemia, Megaloblastic↗
PubMed1984

Interaction of thiamin diphosphate and thiamin thiazolone diphosphate with wheat germ pyruvate decarboxylase.

The interactions of the apoenzyme of wheat germ pyruvate decarboxylase with thiamin diphosphate and with thiamin thiazolone diphosphate have been investigated. The results test hypotheses concerning the structure of the transition state for decarboxylation of the enzyme-bound adduct of pyruvate and thiamin diphosphate. Thiamin thiazolone diphosphate, a possible transition state analogue, binds to the apoenzyme by a two-step process. The first is slow and reversible (k = 200 M-1 s-1; K = 5 X 10(-7) M). The second step is irreversible (k = 1 X 10(-6) s-1). The rate constant for activation by thiamin diphosphate is 160 M-1 s-1. Thiamin diphosphate is released very slowly from the holoenzyme (k = 2 X 10(-5) s-1). Thiamin thiazolone diphosphate competitively inhibits activation of the apoenzyme by thiamin diphosphate, Ki = 2 X 10(-6) M. Km for thiamin diphosphate is only 3 times larger. Thiamin thiazolone is solvated preferentially to thiamin in 2-butanol, a medium whose polarity should resemble that of the binding site. It is concluded that the observed high affinity of thiamin thiazolone diphosphate for the apoenzyme is the result of a combination of effects which do not require the assumption that it is an analogue of the transition state for the decarboxylation of enzyme-bound 2-(2-lactyl) thiamin diphosphate.

Carboxy-Lyases↗
PubMed1982

Effect of 4'-oxythiamine on thiamin transport and phosphorylation by everted jejunal sacs, and on thiamin uptake by rat isolated enterocytes.

Two preparations were used for the present investigation. Rat everted jejunal sacs were incubated at 37 degrees C for 1 h in Krebs-Henseleit buffer, pH 7.4, containing 0.2 microM [thiazole-2-14C] -thiamin, with or without 2 microM 4'-oxythiamine. Suspensions of rat isolated enterocytes were incubated at 37 degrees C for 15 min in Ringer-Krebs, pH 7.4, containing 10 mM d-glucose and 0.125 microM [thiazole-2-14C] -thiamin, with or without 1.25 or 12.50 microM 4'-oxythiamine. Radiometric methods were used for the determination of: labeled thiamin net transport, free and phosphorylated thiamin content in the sac walls, total thiamin content in the isolated enterocytes. 4'-oxythiamine, at a molecular ratio with thiamin of 10:1, did not modify labeled thiamin net transport and accumulation by everted jejunal sacs, but caused a slight, statistically insignificant, decrease of labeled phosphorylated thiamin content of the sac walls. 4'-oxythiamine, at a molecular ratio of 10:1 or 100:1, did not inhibit labeled thiamin uptake by isolated enterocytes. Therefore, 4'-oxythiamine, which is known to be unable to inhibit thiamin enzymatic phosphorylation, did not affect thiamin intestinal transport both by everted intestinal sacs and isolated enterocytes. The present results can be interpreted as a further evidence that intracellular thiamin phosphorylation is an important step in thiamin intestinal transport.

Animals↗
PubMed1984

Absorption and tissue distribution of lead in thiamin-replete and thiamin-deficient rats.

Previous experimental results revealed that thiamin (vitamin B1) reduced lead (Pb) toxicity in calves and decreased tissue lead content in lead-treated calves and rodents. The objective of this experiment was to study the uptake and tissue distribution of lead in rats deprived of thiamin or given excess thiamin and to determine the effect of thiamin on lead absorption. Rats were divided into four groups and fed a thiamin-deficient or thiamin-supplemented diet. The thiamin-replete group also received daily injections of thiamin hydrochloride. Experimental diets were fed for 5 weeks, after which the rats were administered 10 muCi of 203Pb acetate (25 micrograms lead) and killed 6, 24, 48 or 72 hours later. Lead content and concentration of tissues increased twofold in the thiamin-replete group at 24 hours after dosing, but returned to control values 24 hours later. Tissue lead concentration of the thiamin-depleted group was slightly depressed at 24 hours after dosing, but this trend was reversed at the end of the experiment. Tissue lead concentrations in the pair-fed control group were three to seven times greater than in the other treatment groups 6 hours after dosing. The results indicate that thiamin facilitated absorption and increased the amount of lead initially taken up by tissue. Thiamin may also promote more rapid release of lead from tissues.

Animals↗
PubMed1988

Identity of soluble thiamin-binding protein with thiamin-repressible acid phosphatase in Saccharomyces cerevisiae.

Two secretory glycoproteins of Saccharomyces cerevisiae, a soluble thiamin-binding protein and a thiamin-repressible acid phosphatase, were shown to be repressed to a similar extent by excess thiamin in the growth medium. Thiamin-repressible acid phosphatase was co-purified throughout the purification of the soluble thiamin-binding protein. Purified and deglycosylated soluble thiamin-binding proteins exhibited both thiamin-binding and acid phosphatase activity on non-denaturing polyacrylamide gel electrophoresis. Heat treatment of the purified soluble thiamin-binding protein caused a decrease in both activities with a similar inactivation profile. Furthermore, two thiamin-repressible acid phosphatase-defective mutants isolated had no and decreased soluble thiamin-binding activity, respectively. From the results, it was concluded that the soluble thiamin-binding protein is identical to the thiamin-repressible acid phosphatase in S. cerevisiae.

Acid Phosphatase↗
PubMed1996

Thiamine, thiamine phosphates, and their metabolizing enzymes in human brain.

Total thiamine (the sum of thiamine and its phosphate esters) concentrations are two- to fourfold lower in human brain than in the brain of other mammals. There were no differences in the total thiamine content between biopsied and autopsied human brain, except that in the latter, thiamine triphosphate was undetectable. The main thiamine phosphate-metabolizing enzymes could be detected in autopsied brain, and the kinetic parameters were comparable to those reported in other species. Thiamine diphosphate levels were lowest in hippocampus (15 +/- 4 pmol/mg of protein) and highest in mammillary bodies (24 +/- 4 pmol/mg of protein). Maximal levels of thiamine and its phosphate ester were found to be present at birth. In parietal cortex and globus pallidus, mean levels of total thiamine in the oldest age group (77-103 years) were, respectively, 21 and 26% lower than those in the middle age group (40-55 years). Unlike cerebral cortex, the globus pallidus showed a sharp drop in thiamine diphosphate levels during infancy, with concentrations in the oldest group being only approximately 50% of the levels present during the first 4 months of life. These data, consistent with previous observations conducted in blood, suggest a tendency toward decreased thiamine status in older people.

Acid Anhydride Hydrolases↗
PubMed1977

Thiamine pyrophosphokinase activity in liver, heart and brain crude extracts of control and thiamine deficient rats.

The activity of thiamine pyrophosphokinase has been measured in liver, heart muscle and brain of normal and thiamine deficient rats. The activity measurement has been performed by use of thiamine-35S as substrate and separation of the reaction products by high voltage electrophoresis. KM has been determined as 7.1.10(-6) mol/l. The activity of thiamine pyrophosphokinase is reduced in liver and heart muscle of thiamine deficient rats significantly, whereas no decrease of the enzyme activity has been found in the brain. The content of thiamine pyrophosphate has been measured in the liver of normal and thiamine deficient rats. Injection of thiamine to deficient rats normalized the content of thiamine pyrophosphate in the liver within 6 hours. Our data suggest that thiamine pyrophosphokinase is an adaptive enzyme, the activity of which depends on the thiamine content of the cells.

Animals↗
PubMed1981

Effect of thiamine deprivation on thiamine metabolism in mice.

Mice were made deficient by thiamin deprivation. Thiamin pyrophosphokinase and thiamin pyrophosphatase activities were measured, and their changes were compared to transketolase (TK), pyruvate and alpha-ketoglutarate dehydrogenase (DG) activities and thiamin pyrophosphate (TPP) level in the same tissues. Thiamin pyrophosphokinase activity was increased on day 10 of thiamin deficiency and remained unchanged within the next period of investigation. Thiamin pyrophosphatase activity decreased after 5 days and was enhanced in 10, 15 and 20 days of deficiency. This fact may be related to the regulatory role of the enzyme in the intertissue vitamin distribution and transport. The liver TPP level was the earliest and most specific indicator of the thiamin status as thiamin deficiency developed, and pyruvate DG was more drastically inhibited than alpha-ketoglutarate DG. Blood TK was more sensitive to thiamin deprivation than liver TK. In both cases we obtained a more (20-40% in blood) or less (5-10% in liver) pronounced TPP-stimulatory effect of transketolase activity.

Animals↗
PubMed1990

Effects of thiamine deficiency on thiamine-dependent enzymes in regions of the brain of pregnant rats and their offspring.

Thiamine needs in pregnancy and lactation are known to be increased. Previous studies suggest that developing rat brain is more susceptible to a lack of thiamine intake than is adult brain. In order to study the basis of this susceptibility, activities of the three thiamine-dependent enzymes [pyruvate dehydrogenase complex (PDHC), alpha-ketoglutarate dehydrogenase (alpha KGDH), and transketolase (TK)] were measured in homogenates of brain tissue from thiamine-deficient female rats and their offspring. The study revealed a more rapid progression of thiamine deficiency in pregnant thiamine-deficient rats compared to nonpregnant rats as seen by significantly increased "TPP effect" values. No differences in activities of the three thiamine-dependent enzymes in brain were observed between pregnant and nonpregnant animals. However, activities of all three thiamine-dependent enzymes were significantly reduced in cerebral cortex of the offspring of thiamine-deficient mothers 13 days postnatally. TK activities were also reduced in cerebellum and brain stem of these animals. Since thiamine-dependent enzymes are important for the establishment of adult patterns of cerebral energy metabolism and also in myelin synthesis, maternal thiamine deficiency resulting in reductions of activities of these enzymes at a vulnerable period in brain development could have serious metabolic consequences leading to permanent neurological sequellae in the offspring.

Animals↗
PubMed1997

Thiamine uptake in human intestinal biopsy specimens, including observations from a patient with acute thiamine deficiency.

Mucosal biopsy specimens obtained by routine endoscopy from 108 human subjects, including one patient with thiamine deficiency, were incubated at 37 degrees C in oxygenated calcium-free Krebs-Ringer solution (pH 7.5) containing tritiated thiamine and [14C]dextran as a marker of adherent mucosal water. The amount of labeled thiamine taken up was measured radiometrically. In subjects with no clinical evidence of thiamine deficiency, 1) thiamine uptake by duodenal mucosa had a hyperbolic time course, reaching equilibrium at 10 min; 2) thiamine concentrations < 2.5 mumol/L were taken up predominantly by a saturable mechanism displaying Michaelis-Menten kinetics (K(m) 4.4 mumol/L and Jmax 2.3 pmol.mg wet tissue-1.6 min-1), whereas higher concentrations were taken up by passive diffusion; 3) thiamine transport had different capacities along the gastrointestinal tract (duodenum >> colon > stomach); and 4) thiamine uptake was competitively inhibited in the duodenum by thiamine analogs, albeit with a different order of potency compared with rats, and was blocked by 2,4-dinitrophenol. In the thiamine-deficient patient, the duodenal saturable uptake was increased, with higher K(m) and Jmax values. In conclusion, physiologic concentrations of thiamine were transported in human small intestine by a specific mechanism dependent on cellular metabolism, whose transporters appear to be down-regulated.

Adolescent↗
PubMed1987

Comparison of transketolase activity and thiamin pyrophosphate levels in erythrocytes and liver of rainbow trout (Salmo gairdneri) as indicators of thiamin status.

Yearling rainbow trout (Salmo gairdneri) were fed a purified diet with and without thiamin supplementation for 30 wk, at which time overt signs of thiamin deficiency appeared in the deficient group. Overt signs of thiamin deficiency were anorexia, darkening and ataxia. Death rapidly followed the development of overt thiamin deficiency. Transketolase activity and thiamin pyrophosphate levels were measured monthly in erythrocyte and liver samples. Significant differences in erythrocyte transketolase activity between fish fed the thiamin-deficient and control diets were measured after 24 wk of feeding. No significant difference in liver transketolase activity was found between trout fed diets with or without thiamin supplementation. Thiamin pyrophosphate levels were significantly lower in erythrocytes and liver of fish fed the thiamin-deficient diet after 16 wk of feeding. Thiamin pyrophosphate levels in erythrocytes and liver were found to be a more sensitive indicator of thiamin status of rainbow trout than erythrocyte or liver transketolase activity.

Animals↗