(1/212) Thiamine deficiency is prevalent in a selected group of urban Indonesian elderly people.
This cross-sectional study involved 204 elderly individuals (93 males and 111 females). Subjects were randomly recruited using a list on which all 60-75 y-old-people living in seven sub-villages in Jakarta were included. The usual food intake was estimated using semiquantitative food frequency questionnaires. Hemoglobin, plasma retinol, vitamin B-12, red blood cell folate and the percentage stimulation of erythrocyte transketolase (ETK), as an indicator of thiamine status, were analyzed. Median energy intake was below the assessed requirement. More than 75% of the subjects had iron and thiamine intakes of approximately 2/3 of the recommended daily intake, and 20.2% of the study population had folate intake of approximately 2/3 of the recommended daily intake. Intakes of vitamins A and B-12 were adequate. Biochemical assessments demonstrated that 36.6% of the subjects had low thiamine levels (ETK stimulation > 25%). The elderly men tended to have lower thiamine levels than the elderly women. The overall prevalence of anemia was 28.9%, and the elderly women were affected more than the elderly men. Low biochemical status of vitamins A, B-12 and RBC folate was found in 5.4%, 8.8 % and 2.9% of the subjects, respectively. Dietary intakes of thiamine and folate were associated with ETK stimulation and plasma vitamin B-12 concentration (r = 0.176, P = 0.012 and r = 0.77, P = 0.001), respectively. Results of this study suggest that anemia, thiamine and possibly vitamin B-12 deficiency are prevalent in the elderly living in Indonesia. Clearly, micronutrient supplementation may be beneficial for the Indonesian elderly population living in underprivileged areas. (+info)
(2/212) Behavior of transaldolase (EC 126.96.36.199) and transketolase (EC 188.8.131.52) Activities in normal, neoplastic, differentiating, and regenerating liver.
The objective of this investigation was to throw light on the biological behavior and metabolic regulation of hepatic enzymes of the nonoxidative branch of the pentose phosphate pathway. The activities of transaldolase (EC 184.108.40.206) and trasketolase (EC 220.127.116.11) Were compared in biological conditions that involve modulation of gene expression such as in starvation, in differentiation, after partial hepatectomy, and in a spectrum of hepatomas of different growth rates. The enzyme activities were determined under optimal kinetic conditions by spectrophotometric methods in the 100,000 X g supernatant fluids prepared from tissue homogenates. The kinetic properties of transaldolase and transketolase were similar in normal liver and in rapidly growing hepatoma 3924A. For transaldolase, apparent Km values of 0.13 mM (normal liver) and 0.17 mM (hepatoma) were observed for erythrose 4-phosphate and of 0.30 to 0.35 mM for fructose 6-phosphate. The pH optima in liver and hepatoma were at approximately 6.9 to 7.2. For the transketolase substrates, ribose 5-phosphate and xylulose 5-phosphate, the apparent Km values were 0.3 and 0.5 mM, respectively, in both liver and hepatoma. A broad pH optimum around 7.6 was observed in both tissues. In organ distribution studies, enzyme activities were measured in liver, intestinal mucosa, thymus, kidney, spleen, brain, adipose tissue, lung, heart, and skeletal muscle. Taking the specific activity of liver as 100%, transaldolase activity was the highest in intestinal mucosa (316%) and in thymus (219%); it was the lowest in heart (53%) and in skeletal muscle (21%). Transketolase activity was highest in kidney (155%) and lowest in heart (26%) and skeletal muscle (23%). Starvation decreased transaldolase and transketolase activities in 6 days to 69 and 74%, respectively, of those of the liver of the normal, fed rat. This was in the same range as the decrease in the protein concentration (66%y. In the liver tumors, transaldolase activity was increased 1.5- to 3.4-fold over the activities observed in normal control rat liver. Transketolase activity showed no relationship to tumor proliferation rate. In the regenerating liver at 24 hr after partial hepatectomy, the activity of both pentose phosphate pathway enzymes was in the same range as that of the sham-operated controls. In differentiation at the postnatal age of 5, 12, 23, and 32 days, hepatic transaldolase activities were 33, 44, 55, and 72%, respectively, of the activities observed in the 60-day-old, adult male rat. During the same period, transketolase activ-ties were 18, 21, 26, and 55% of the activities observed in liver of adult rat. The demonstration of increased transaldolase activity in hepatomas, irrespective of the degree of tumor malignancy, differentiation, or growth rate, suggests that the reprogramming of gene expression in malignant transformation is linked with an increase in the expression of this pentose phosphate pathway enzyme... (+info)
(3/212) Hyperproduction of tryptophan by Corynebacterium glutamicum with the modified pentose phosphate pathway.
A classically derived tryptophan-producing Corynebacterium glutamicum strain was recently significantly improved both by plasmid-mediated amplification of the genes for the rate-limiting enzymes in the terminal pathways and by construction of a plasmid stabilization system so that it produced more tryptophan. This engineered strain, KY9218 carrying pKW9901, produced 50 g of tryptophan per liter from sucrose after 80 h in fed-batch cultivation without antibiotic pressure. Analysis of carbon balances showed that at the late stage of the fermentation, tryptophan yield decreased with a concomitant increase in CO2 yield, suggesting a transition in the distribution of carbon flow from aromatic biosynthesis toward the tricarboxylic acid cycle via glycolysis. To circumvent this transition by increasing the supply of erythrose 4-phosphate, a direct precursor of aromatic biosynthesis, the transketolase gene of C. glutamicum was coamplified in the engineered strain by using low- and high-copy-number plasmids which were compatible with the resident plasmid pKW9901. The presence of the gene in low copy numbers contributed to improvement of tryptophan yield, especially at the late stage, and led to accumulation of more tryptophan (57 g/liter) than did its absence, while high-copy-number amplification of the gene resulted in a tryptophan production level even lower than that resulting from the absence of the gene due to reduced growth and sugar consumption. In order to assemble all the cloned genes onto a low-copy-number plasmid, the high-copy-number origin of pKW9901 was replaced with the low-copy-number one, generating low-copy-number plasmid pSW9911, and the transketolase gene was inserted to yield pIK9960. The pSW9911-carrying producer showed almost the same fermentation profiles as the pKW9901 carrier in fed-batch cultivation without antibiotic pressure. Under the same culture conditions, however, the pIK9960 carrier achieved a final tryptophan titer of 58 g/liter, which represented a 15% enhancement over the titers achieved by the pKW9901 and pSW9911 carriers. (+info)
(4/212) Vitamin B status in patients with chronic fatigue syndrome.
Some patients with chronic fatigue syndrome say they benefit from taking vitamin supplements. We assessed functional status for the B vitamins pyridoxine, riboflavin and thiamine in 12 vitamin-untreated CFS patients and in 18 healthy controls matched for age and sex. Vitamin-dependent activities--aspartate aminotransferase (AST) for pyridoxine, glutathione reductase (GTR) for riboflavin, transketolase (TK) for thiamine--were measured in erythrocyte haemolysates before and after in-vitro addition of the relevant vitamin. For all three enzymes basal activity (U/g Hb) was lower in CFS patients than in controls: AST 2.84 (SD 0.62) vs 4.61 (1.43), P < 0.001; GTR 6.13 (1.89) vs 7.42 (1.25), P < 0.04; TK 0.50 (0.13) vs 0.60 (0.07), P < 0.04. This was also true of activated values: AST 4.91 (0.54) vs 7.89 (2.11), P < 0.001; GTR 8.29 (1.60) vs 10.0 (1.80), P < 0.001; TK 0.56 (0.19) vs 0.66 (0.08), P < 0.07. The activation ratios, however, did not differ between the groups. These data provide preliminary evidence of reduced functional B vitamin status, particularly of pyridoxine, in CFS patients. (+info)
(5/212) Oxythiamine and dehydroepiandrosterone induce a G1 phase cycle arrest in Ehrlich's tumor cells through inhibition of the pentose cycle.
Transketolase (TK) reactions play a crucial role in tumor cell nucleic acid ribose synthesis utilizing glucose carbons, yet, current cancer treatments do not target this central pathway. Experimentally, a dramatic decrease in tumor cell proliferation after the administration of the TK inhibitor oxythiamine (OT) was observed in several in vitro and in vivo tumor models. Here, we demonstrate that pentose cycle (PC) inhibitors, OT and dehydroepiandrosterone (DHEA), efficiently regulate the cell cycle and tumor proliferation processes. Increasing doses of OT or DHEA were administered by daily intraperitoneal injections to Ehrlich's ascites tumor hosting mice for 4 days. The tumor cell number and their cycle phase distribution profile were determined by DNA flow histograms. Tumors showed a dose dependent increase in their G0-G1 cell populations after both OT and DHEA treatment and a simultaneous decrease in cells advancing to the S and G2-M cell cycle phases. This effect of PC inhibitors was significant, OT was more effective than DHEA, both drugs acted synergistically in combination and no signs of direct cell or host toxicity were observed. Direct inhibition of PC reactions causes a G1 cell cycle arrest similar to that of 2-deoxyglucose treatment. However, no interference with cell energy production and cell toxicity is observed. PC inhibitors, specifically ones targeting TK, introduce a new target site for the development of future cancer therapies to inhibit glucose utilizing pathways selectively for nucleic acid production. (+info)
(6/212) Biochemical evidence of thiamin deficiency in young Ghanian children.
Detailed biochemical studies for nutritional status were carried out on 146 Ghanaian children ages 6 months to 6 years over a 2-year period. Study children comprised three main groups: severe protein-calorie malnutrition; mild to moderate protein-calorie malnutrition and apparently healthy children. Erythrocyte transketolase activity and the percentage of erythrocyte transketolase pyrophosphate effect were also determined. In the first year of the study elevated percentage of transketolase pyrophosphate effect indicative of thiamin deficiency was found in all three of the above-mentioned groups, with the most widespread deficiency in the normal groups. In year 2, repeat studies of the severely malnourished group after 2 weeks of nutritional therapy with the administration of vitamin capsules, which included thiamin, resulted in the normalization of transketolase pyrophosphate effect. Apoenzyme activity was comparable in all groups studied. There were no obvious clinical signs of thiamin deficiency, although sensory testing was not performed. A relatively large number of children with high percentage of transketolase pyrosphosphate effect also had serum folic acid deficiency. This evidence of widespread biochemical thiamin deficiency is indicative of an at-risk population among young children for clinical thiamin deficiency. Further studies are needed to identify whether the problem is inadequate thiamin intake, destruction of thiamin by thiaminases or food preparation methods, or malabsorption of thiamin. (+info)
(7/212) Thiamin and pyridoxine requirements during intravenous hyperalimentation.
Studies were undertaken to determine rational dosages of vitamin B1 and B6 during long-term intravenous hyperalimentation, using more sensitive techniques than formerly used to evaluate B1 and B6 status. A standard vitamin combination, type A, (usually commercially available products) has been used up to now because of convenience, disregarding the effects of long-term administration. This combination lacks biotin, folic acid, and vitamin E and contains from 10 to 100 times the dietary allowances of such vitamins as B1, B2, B6, B12, and C. In response to the possibility of vitamin overdose, two new vitamin combinations, type B (from commercial products) and type C (a convenient and easily administered combination produced at the hospital) were developed in order to provide the normal dietary allowances and at the same time eliminate any harmful side-effects. From the results obtained, 5 mg/day for thiamin HCl and 3 mg/day for pyridoxine HCl in type B and type C were found to be a sufficient and safe level as opposed to 55 mg/day for thiamin HCl and 102 mg/day for pyridoxine HCl in type A. (+info)
(8/212) Molecular analysis of the Corynebacterium glutamicum transketolase gene.
Transketolase is important in production of the aromatic amino acids in Corynebacterium glutamicum. The complete nucleotide sequence of the C. glutamicum transketolase gene has been identified. The DNA-derived protein sequence is highly similar to the transketolase of Mycobacterium tuberculosis, taxonomically related to C. glutamicum. The alignment of the N-terminus regions between both transketolases showed TTG to be the most probable start codon. Potential ribosomal binding and promoter regions were situated upstream from the TTG. The deduced amino acid sequence consists of 700 residues with a calculated molecular mass of 75 kDa, and contains all amino acid residues involved in cofactor and substrate binding in the well-characterized yeast transketolase sequence. (+info)