Showing papers on "Thiamine published in 2004"

SLC19: the folate/thiamine transporter family

Abstract: The SLC19 gene family of solute carriers is a family of three transporter proteins with significant structural similarity, transporting, however, substrates with different structure and ionic charge. The three members of this gene family are expressed ubiquitously and mediate the transport of two important water-soluble vitamins, folate and thiamine. The concentrative transport of substrates mediated by the members of this gene family is energized by transcellular H+/OH− gradient. SLC19A1 is expressed at highest levels in absorptive cells where it is located in a polarized manner either in the apical or basal membrane, depending on the cell type. It mediates the transport of reduced folate and its analogs, such as methotrexate, which are anionic at physiological pH. SLC19A2 is expressed ubiquitously and mediates the transport of thiamine, a cation at physiological pH. SLC19A3 is also widely expressed and is capable of transporting thiamine. This review summarizes the current knowledge on the structural, functional, molecular and physiological aspects of the SLC19 gene family.

Nutrition and alcoholic liver disease.

Abstract: Malnutrition is a common finding in chronic alcoholics, and protein calorie malnutrition (PCM) is universal and predictive of survival in patients with established alcoholic liver disease (ALD). These patients also demonstrate frequent deficiencies of folate, thiamine, pyridoxine, and vitamin A, which enhance the likelihood of anemia, altered cognitive states, and night blindness. The etiologies of malnutrition in ALD patients are multiple and interactive and include anorexia with inadequate dietary intake, abnormal digestion of macronutrients and absorption of several micronutrients, increased skeletal and visceral protein catabolism, and abnormal interactions of ethanol and lipid metabolism. Numerous, and mostly inadequately controlled, studies have evaluated the potential efficacies of oral, enteral, and parenteral nutrition approaches to treatment of ALD, with mixed results on liver function, clinical improvements, and short- or long-term survival. Targeted metabolic treatments include supplementation with S-adenosylmethionine (SAM) or phosphatidylcholine derivatives, each with promising experimental bases but inconclusive clinical trials.

Maternal dietary B vitamin intake, other than folate, and the association with orofacial cleft in the offspring.

Abstract: Periconceptional folic acid supplementation is suggested to prevent orofacial clefts (OFCs). Other B vitamins however may be beneficial as well. To investigate the maternal periconceptional dietary intake of thiamine, riboflavin, niacin, pyridoxine and cobalamin in association with the occurrence of OFC. Two hundred and six mothers of a child with nonsyndromic OFC and 203 control mothers filled out a general questionnaire and a food frequency questionnaire around 14 months postpartum as a proxy for periconceptional intake. After exclusion of known pregnant and lactating mothers, those who reported to have altered their diet compared to the periconceptional period, and mothers with incidental folic acid supplement use periconceptionally, data of 182 OFC mothers and 173 controls were analysed. After logarithmic transformation, geometric means (P5-P95) were calculated and compared between the groups. After subsequent adjustment for energy, quintiles of dietary B vitamin intake were created. The periconceptional intake of thiamine, niacin and pyridoxine was significantly lower in mothers of an OFC child. A trend towards risk reduction for OFC with increasing dietary intake was demonstrated for thiamine (p = 0.04) and pyridoxine (p = 0.03). Risk reductions were only demonstrated in women using folic acid supplements periconceptionally. Supplement users tended to consume a diet richer in B vitamins. Periconceptional intake of thiamine, niacin and pyridoxine seems to contribute to the prevention of OFC.

High-dose thiamine therapy counters dyslipidaemia in streptozotocin-induced diabetic rats.

Abstract: Aims/hypothesis Cardiovascular disease in diabetes is linked to increased risk of atherosclerosis, increased levels of triglyceride-rich lipoproteins and enhanced hepatic lipogenesis. The hepatic hexosamine pathway has been implicated in signalling for de novo lipogenesis by the liver. In this study, we assessed if decrease of flux through the hexosamine pathway induced by high-dose thiamine therapy counters diabetic dyslipidaemia.

Cu2+ toxicity inhibition of mitochondrial dehydrogenases in vitro and in vivo.

Abstract: Wilson's disease results from mutations in the P-type Cu(2+)-ATPase causing Cu(2+) toxicity. We previously demonstrated that exposure of mixed neuronal/glial cultures to 20 microM Cu(2+) induced ATP loss and death that were attenuated by mitochondrial substrates, activators, and cofactors. Here, we show differential cellular sensitivity to Cu(2+) that was equalized to 5 microM in the presence of the copper exchanger/ionophore, disulfiram. Because Cu(2+) facilitates formation of oxygen radicals (ROS) which inhibit pyruvate dehydrogenase (PDH) and alpha-ketoglutarate dehydrogenase (KGDH), we hypothesized that their inhibition contributed to Cu(2+)-induced death. Toxic CU(2+) exposure was accompanied by early inhibition of neuronal and hepatocellular PDH and KGDH activities, followed by reduced mitochondrial transmembrane potential, DeltaPsi(M). Thiamine (1-6 mM), and dihydrolipoic acid (LA, 50 microM), required cofactors for PDH and KGDH, attenuated this enzymatic inhibition and subsequent death in all cell types. Furthermore, liver PDH and KGDH activities were reduced in the Atp7b mouse model of Wilson's disease prior to liver damage, and were partially restored by oral thiamine supplementation. These data support our hypothesis that Cu(2+)-induced ROS may inhibit PDH and KGDH resulting in neuronal and hepatocellular death. Therefore, thiamine or lipoic acid may constitute potential therapeutic agents for Wilson's disease.

NAD+ modulates p53 DNA binding specificity and function.

Abstract: DNA damage induces p53 DNA binding activity, which affects tumorigenesis, tumor responses to therapies, and the toxicities of cancer therapies (B. Vogelstein, D. Lane, and A. J. Levine, Nature 408:307-310, 2000; K. H. Vousden and X. Lu, Nat. Rev. Cancer 2:594-604, 2002). Both transcriptional and transcription-independent activities of p53 contribute to DNA damage-induced cell cycle arrest, apoptosis, and aneuploidy prevention (M. B. Kastan et al., Cell 71:587-597, 1992; K. H. Vousden and X. Lu, Nat. Rev. Cancer 2:594-604, 2002). Small-molecule manipulation of p53 DNA binding activity has been an elusive goal, but here we show that NAD(+) binds to p53 tetramers, induces a conformational change, and modulates p53 DNA binding specificity in vitro. Niacinamide (vitamin B(3)) increases the rate of intracellular NAD(+) synthesis, alters radiation-induced p53 DNA binding specificity, and modulates activation of a subset of p53 transcriptional targets. These effects are likely due to a direct effect of NAD(+) on p53, as a molecule structurally related to part of NAD(+), TDP, also inhibits p53 DNA binding, and the TDP precursor, thiamine (vitamin B(1)), inhibits intracellular p53 activity. Niacinamide and thiamine affect two p53-regulated cellular responses to ionizing radiation: rereplication and apoptosis. Thus, niacinamide and thiamine form a novel basis for the development of small molecules that affect p53 function in vivo, and these results suggest that changes in cellular energy metabolism may regulate p53.

Thiamine and benfotiamine prevent increased apoptosis in endothelial cells and pericytes cultured in high glucose.

Abstract: Background High glucose induces pathological alterations in small and large vessels, possibly through increased formation of AGE, activation of aldose reductase and protein kinase C, and increased flux through the hexosamine pathway. We showed previously that thiamine and benfotiamine correct delayed replication and increase lactate production in endothelial cells subjected to high glucose. We now aim at verifying the effects of thiamine and benfotiamine on cell cycle, apoptosis, and expression of adhesion molecules in endothelial cells and pericytes, under high ambient glucose. Methods Human umbilical vein endothelial cells and bovine retinal pericytes were cultured in normal (5.6 mmol/L) or high (28 mmol/L) glucose, with or without thiamine or benfotiamine, 50 or 100 µmol/L. Apoptosis was determined by two separate ELISA methods, measuring DNA fragmentation and caspase-3 activity, respectively. Cell cycle and integrin subunits α3, α5, and β1 concentration were measured by flow cytometry. Results Apoptosis was increased in high glucose after 3 days of culture, both in endothelium and pericytes. Thiamine and benfotiamine reversed such effects. Neither cell cycle traversal nor integrin concentrations were modified in these experimental conditions. Conclusions Thiamine and benfotiamine correct increased apoptosis due to high glucose in cultured vascular cells. Further elucidations of the mechanisms through which they work could help set the basis for clinical use of this vitamin in the prevention and/or treatment of diabetic microangiopathy. Copyright © 2004 John Wiley & Sons, Ltd.

Novel mutation in the SLC19A2 gene in an African-American female with thiamine-responsive megaloblastic anemia syndrome.

Abstract: Thiamine-responsive megaloblastic anemia (TRMA) syndrome is an autosomal recessive disorder characterized by diabetes mellitus (DM), progressive sensorineural deafness, and thiamine-responsive anemia. Mutations in the SLC19A2 gene encoding a high-affinity thiamine transporter protein THTR-1 are responsible for the clinical features associated with TRMA syndrome. We report an African-American female with TRMA-syndrome associated with thyroid disease and retinitis pigmentosa caused by a novel mutation in the SLC19A2 gene. The patient presented at 12 months of age with paroxysmal atrial tachycardia and hepatosplenomegaly. One month later, she developed DM requiring intermittent insulin therapy. At 2-1/2 years of age, profound sensorineural hearing loss was discovered. By 4 years of age, daily insulin therapy (0.5 U/kg/day) was instituted and her insulin requirement gradually increased to 1.0 U/kg/day by 9 years of age. She developed optic atrophy, retinitis pigmentosa, and visual impairment by 12 years of age with severe restriction of peripheral vision by 16 years. At age 19, a thiamine-responsive normocytic anemia was discovered. She was diagnosed with autoimmune thyroiditis at 20 years and she experienced a psychotic episode associated with a mood disorder at age 21. With oral thiamine therapy, her insulin requirement decreased by 30% over a 20 month period. Molecular analysis revealed that the patient is homozygous for a missense mutation (C152T) in exon 1 of the SLC19A2 gene.

Identification of the Two Missing Bacterial Genes Involved in Thiamine Salvage: Thiamine Pyrophosphokinase and Thiamine Kinase

Abstract: The genes encoding thiamine kinase in Escherichia coli (ycfN) and thiamine pyrophosphokinase in Bacillus subtilis (yloS) have been identified. This study completes the identification of the thiamine salvage enzymes in bacteria.

Reduced concentrations of several vitamins in normal weight patients with late-onset dementia of the Alzheimer type without vascular disease

Abstract: BACKGROUND There is an uncertainty to what an extent initiation of late onset dementia of the Alzheimer type (DAT) is related to nutritional factors OBJECTIVE To find any differences in nutrient concentrations between women (75-85 y), well-nourished with moderate DAT, and a control group, all without vascular disease DESIGN A case control study assessing clinical, anthropometrical, biochemical and micronutrient characteristics of 20 DAT patients and 18 free-living healthy women RESULTS Significant differences (* = p < 005) were found for the following nutrients, given in sequence (Mean (SD)) for controls and DAT patients, respectively: Thiamine (nmol/L): 117 (69), 71(37)*; Blood thiamine diphosphate (nmol/L): 860 (125), 658 (275)*; Pyridoxal-5-phosphate 902 (14), 248 (33)*; Cobalamin (nmol/L) 435(263), 350 (264)*; Homocysteine (mmol/L) 147 (13), 185 (16)*; Ascorbic acid (mmol/L) 777 (28), 462 (25)*; alpha-tocopherol (mmol/L) 382 (92), 271 (115)*; Serum and blood thiamine mono-phosphate and ascorbic acid in cerebrospinal fluid were significantly different as well Age, BMI, MMSE, MADRS, 'Vascular Score ' and a set of other biochemical parameters were similar between the groups Using logistic regression analysis, models for predicting the presence of DAT all contained pyridoxal-5-phosphate, and CSF-protein, in combination with either one of variables, age, ascorbic acid, retinol, alpha-tocopherol, homocysteine, thiamin-diphosphate, CSF-thiamin All the models give complete separation between DAT and controls CONCLUSIONS The presence of reduced concentrations of several vitamins in the DAT patients compared to the controls might indicate that these nutrients may contribute to the development of DAT

Fatal metabolic acidosis caused by thiamine deficiency.

Abstract: Acute thiamine deficiency, an uncommon cause of hemodynamic instability in Western countries, may be manifested by acute heart failure and neurological deficits. Severe metabolic acidosis is one of its least recognized features. We present a report of foreign workers who complained of weakness and lower limb edema and were found to have acute thiamine deficiency. One died of refractory metabolic acidosis and shock, and the diagnosis was reached post mortem. Thiamine deficiency should be considered in every case of severe lactic acidosis without an obvious cause, especially in high-risk populations (malnourished, alcoholics, Far-East workers, etc). Whenever it is suspected, empiric treatment with thiamine should be initiated immediately. Physicians who care for populations at risk should be familiar with the clinical spectrum of nutritional deficits, and monitor the nutritional habits of these patients carefully. The treatment is inexpensive and devoid of adverse effects. Moreover, delaying thiamine administration in patients with deficiency may cause severe life-threatening metabolic acidosis and affect recovery. The prophylactic use of thiamine in a high-risk population, even before blood levels are received, may be cost effective.

Thiamine transporter gene expression and exogenous thiamine modulate the expression of genes involved in drug and prostaglandin metabolism in breast cancer cells.

Abstract: In previous studies, we have shown that RNA levels of the thiamine transporter THTR2 were down-regulated in breast cancer tumors in comparison with normal tissues and that THTR2-mediated increases in thiamine uptake activity contributed to increased apoptosis after exposure to ionizing radiation. To further understand the biological effects of the alteration of THTR2 expression, we conducted a DNA microarray study of gene expression in THTR2-transfected breast cancer cells and found that, in addition to increased expression of THTR2 attributable to the transgene, three other genes were up-regulated >2.5-fold in the transfected cells: cytochrome P450 isoform CYP4B1, 15-hydroxyprostaglandin dehydrogenase (15-PGDH), and transcription factor CRIP1. In addition, two genes were confirmed to be down-regulated in THTR2-transfected cells: trefoil factor 1 (TFF1) and Rho-GDP dissociation inhibitor (RGDI). Up-regulation of 15-PGDH and CYP4B1 expression was observed in other breast cancer cell lines transfected with THTR2, and down-regulation was observed after suppression of THTR2 with siRNA vectors. To determine the role of exogenous thiamine in the expression of these genes, we analyzed THTR2-transfected breast cancer cells grown in thiamine-depleted medium by quantitative reverse transcription-PCR and showed that three of these five genes showed evidence of regulation by exogenous thiamine in a manner concordant with the effects of THTR2 overexpression. One of the genes up-regulated by THTR2 transfection was down-regulated by thiamine depletion (CYP4B1), and two genes with decreased expression in THTR2-transfected breast cancer cells were up-regulated by thiamine depletion (TFF1 and RGDI). In summary, these studies show unexpected relationships between thiamine metabolism and genes that may be involved in the oncogenesis of breast and lung cancer.

Simultaneous Determination of Thiamine and Riboflavin in Edible Marine Seaweeds by High-Performance Liquid Chromatography

Abstract: This study presents a high-performance liquid chromatography (HPLC) method for simultaneous determination of thiamine and riboflavin and the results of its application to a number of edible seaweeds that are sampled in dried form (Himanthalia elongata, Laminaria ochroleuca, Undaria pinnatifida, Palmaria sp., and Porphyra sp.) or as canned food (H. elongata and Saccorhiza polyschides). Samples are prepared by acid and enzymatic hydrolysis. Optimized conditions for reversed-phase HPLC with fluorescence detection are as follow: column, Kromasil 100 C18; column temperature, 35 degrees C; mobile phase, a 72:28 (v/v) mixture of 0.005 M ammonium acetate (pH 6.7)-methanol; and flow rate, 1.35 mL/min. With these conditions, recovery is 95.52% for thiamine and 90.08% for riboflavin, and the method precision (relative standard deviation) is 2.66% for thiamine and 2.21% for riboflavin. On a dry weight basis, thiamine contents range from 0.14 microg/g in dried H. elongata to 2.02 microg/g in dried Porphyra and riboflavin contents from 0.31 microg/g in canned H. elongata to 6.15 microg/g in dried Porphyra.

Thiamine pyrophosphate biosynthesis and transport in the nematode Caenorhabditis elegans.

Abstract: Thiamine (vitamin B1) is required in the diet of animals, and thiamine deficiency leads to diseases such as beri-beri and the Wernicke-Korsakoff syndrome. Dietary thiamine (vitamin B1) consists mainly of thiamine pyrophosphate (TPP), which is transformed into thiamine by gastrointestinal phosphatases before absorption. It is believed that TPP itself cannot be transported across plasma membranes in significant amounts. We have identified a partial loss-of-function mutation in the Caenorhabditis elegans gene (tpk-1) that encodes thiamine pyrophosphokinase, which forms TPP from thiamine at the expense of ATP inside cells. The mutation slows physiological rhythms and the phenotype it produces can be rescued by TPP but not thiamine supplementation. tpk-1 functions cell nonautonomously, as the expression of wild-type tpk-1 in one tissue can rescue the function of other tissues that express only mutant tpk-1. These observations indicate that, in contrast to expectation from previous evidence, TPP can be transported across cell membranes. We also find that thiamine supplementation partially rescues the phenotype of partial loss-of-function mutants of the Na/K ATPase, providing genetic evidence that thiamine absorption, and/or redistribution from the absorbing cells, requires the full activity of this enzyme.

Thiamine attenuates hypoxia-induced cell death in cultured neonatal rat cardiomyocytes.

Abstract: Previous studies have demonstrated that thiamine (vitamin B1) has a cytoprotective effect against ischemic damage to the heart, and that heat shock protein 70 (Hsp70) is capable of protecting cardiac cells from lethal ischemia/hypoxia. We show here that thiamine has a cytoprotective effect on cultured neonatal rat cardiomyocytes under hypoxic insult, and also protects the cardiomyocytes against hypoxia-induced apoptosis; caspase-3 activation, PARP cleavage and DNA fragmentation are all inhibited. Moreover, it increases the level of Hsp70 protein in the cardiomyocytes even under prolonged hypoxic stress and its effects on hypoxia-induced cardiac cell death are antagonized by an Hsp70 inhibitor. These results suggest that the cytoprotective effect of thiamine in cardiomyocytes under hypoxic stress is due to its ability to induce Hsp70.