Effect of high dose thiamine therapy on activity and molecular aspects of transketolase in Type 2 diabetic patients

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Commonest form of diabetes mellitus is Type 2, treated with oral hypoglycemic agents, which often carry potential adverse effects and do not address the intracellular metabolism of glucose. Thiamine is an essential co-factor for vital subcellular enzymes and has potential to benefit Type 2 diabetics. This study was therefore designed to investigate the effect of high dose thiamine therapy on the activity and molecular aspects of transketolase in Type 2 diabetic patients. Over 100 Type 2 microalbuminuric diabetics were enrolled in a randomized, double blind placebo controlled clinical trial for 6 months. Patients were divided into two groups, one treated with 300 mg/day thiamine and the other group was administered placebo for a period of 3 months followed by a 2 month washout period. 50 normal healthy controls participated for baseline estimations only. Transketolase activity of mononuclear cells and erythrocytes were determined. Also q-polymerase chain reaction (PCR) was used to determine expression levels of transketolase gene in mononuclear cells. All enrolled Type 2 diabetics had > 40% lower mononuclear transketolase activity as compared to healthy individuals. Thiamine therapy for three months resulted in a 65% significant increase in transketolase activity which persisted into washout period. Mononuclear transketolase gene expression was significantly reduced in Type 2 diabetics as compared to normal controls (0.66 fold thiamine group) and (0.89 fold) placebo group). High dose thiamine therapy resulted in highly significant increase (2.86 fold) in expression of transketolase gene in mononuclear cells which was sustained at 2.91 fold after washout period. These results indicate that high dose thiamine therapy improves both transketolase activity and expression in Type 2 diabetic patients with incipient nephropathy.

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... Thiamine (vitamin B1) is a water-soluble vitamin and an essential normal dietary component [4]. Thiamine deficiency exists in both type 1 and type 2 diabetes patients [5] and in patients with type 2 diabetes and microalbuminuria [6][7][8][9]. Thiamine and benfotiamine therapy prevents the development of microvascular complications in experimental diabetes [10][11] and could possibly also have a beneficial role to play in the treatment of type 2 diabetes mellitus [5]. ...
... Based on the above evidence a novel strategy to counter biochemical dysfunction linked to the development of diabetic nephropathy is highdose thiamine therapy. In our previous published pilot study, we evaluated the effect of oral high dose supplements of thiamine on urinary albumin excretion (UAE), a marker of early-stage diabetic nephropathy, in type 2 diabetic patients with microalbuminuria and an improvement in microalbuminuria and transketolase levels [6,9]. AKDH and PDH are both thiamine dependent enzymes as well, required for effective utilization of the glucose intracellularly in all tissues including the kidney and in generation of ATP for all processes including renal function. ...
... Our research on activity and expression analysis of PDE1 and alphaketoglutarate dehydrogenase in mononuclear cells revealed continued increment of both activity and expression levels of these enzymes after 3 months of high dose thiamine therapy and its persistence even 2 months after stoppage of therapy. The mean baseline plasma thiamine levels of the diabetic patients were found to be directly proportional to their enzyme activities and expression levels i.e both showed improvement with thiamine therapy [6][7][8][9]. ...
... Transketolase plays a fundamental role in intracellular glucose metabolism by shifting excess F-6-P from glycolysis into the pentose phosphate pathway, thereby preventing activation of the hexosamine pathway and decreasing methylglyoxal formation as described above (Beltramo et al., 2008). Patients with diabetes show a high prevalence of thiamine and transketolase deficiency (Thornalley et al., 2007;Alam et al., 2011), and high doses of thiamine in combination with pyridoxine (vitamin B 6 ) improved neuropathic symptoms in patients with diabetes who have DPN (Abbas and Swai, 1997). ...
Diabetic peripheral neuropathy (DPN) is a common complication of diabetes that is associated with axonal atrophy, demyelination, blunted regenerative potential, and loss of peripheral nerve fibers. The development and progression of DPN is due in large part to hyperglycemia but is also affected by insulin deficiency and dyslipidemia. Although numerous biochemical mechanisms contribute to DPN, increased oxidative/nitrosative stress and mitochondrial dysfunction seem intimately associated with nerve dysfunction and diminished regenerative capacity. Despite advances in understanding the etiology of DPN, few approved therapies exist for the pharmacological management of painful or insensate DPN. Therefore, identifying novel therapeutic strategies remains paramount. Because DPN does not develop with either temporal or biochemical uniformity, its therapeutic management may benefit from a multifaceted approach that inhibits pathogenic mechanisms, manages inflammation, and increases cytoprotective responses. Finally, exercise has long been recognized as a part of the therapeutic management of diabetes, and exercise can delay and/or prevent the development of painful DPN. This review presents an overview of existing therapies that target both causal and symptomatic features of DPN and discusses the role of up-regulating cytoprotective pathways via modulating molecular chaperones. Overall, it may be unrealistic to expect that a single pharmacologic entity will suffice to ameliorate the multiple symptoms of human DPN. Thus, combinatorial therapies that target causal mechanisms and enhance endogenous reparative capacity may enhance nerve function and improve regeneration in DPN if they converge to decrease oxidative stress, improve mitochondrial bioenergetics, and increase response to trophic factors.
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The patients with chronic pancreatitis or with their pancreas being removed are observed with a high percentage of Diabetes Type 3c, yet they are mostly confused with type 1 or type 2 diabetes. Chronic pancreatitis is the leading cause of Type 3c DM along with hemochromatosis and adenocarcinoma etc. The pancreatic tissue abnormality and loss of islet's cells result in the declination in insulin production and hyperglycemic conditions with clinical presentation of abdominal pain, bloating, steat-orrhea or maldigestion, and glucose intolerance sometimes in association with PEI. True diagnosis for Type 3c must include pathological pancreatic imaging, and the patient should be checked for PEI as the absence of pancreatic enzyme is another true indicator of type 3c. The DM insulin replacement therapy is preferred for treating Type 3c DM to achieve optimal glucose concentration in blood.
In 46 diabetic outpatients consisting of 20 males and 26 females not given thiamine treatment, the blood thiamine level was 46.9 +/- 28.5 ng/ml (mean +/- SD) and only 23.9% of all cases had a value of more than the normal lower limit (50 ng/ml). Erythrocyte transketolase activity was 443.8 +/- 107.7 micrograms/ml/h and only 20.9% had a value of ore than the normal lower limit (50 micrograms/ml/h), and the erythrocyte TPP effect was 16.6 +/- 13.2%. Moreover, there was a significant positive correlation (r = 0.97) between the blood thiamine level and erythrocyte transketolase activity, and a significant inverse correlation (r = -0.525, r = -0.576) between blood thiamine level and/or erythrocyte transketolase activity and the erythrocyte TPP effect. In 24 diabetic outpatients consisting of 14 males and 10 females given thiamine treatment, the blood thiamine level was 96.5 +/- 44.5 ng/ml/h excluding one case (621.7 ng/ml), and it was higher than the normal lower limit in 83% of all cases. Erythrocyte transketolase activity was 513.9 +/- 133.4 micrograms/ml/h and it was higher than the normal lower limit in 58.3%. Erythrocyte TPP effect was 5.84 +/- 8.39%. There was also a significant positive correlation (r = 0.663) between blood thiamine level and erythrocyte transketolase activity, and a significant inverse correlation (r = 0.0668, r = 0.834) between blood thiamine level and/or erythrocyte transketolase activity and erythrocyte TPP effect. Blood thiamine level and erythrocyte transketolase activity were significantly higher in diabetic outpatients given thiamine treatment than in diabetic outpatients not given thiamine treatment, while the erythrocyte TPP effect was significantly lower in diabetic outpatients given thiamine treatment than in diabetic outpatients not given thiamine treatment. There was no direct relationship between the lowered response of patellar tendon reflex and the biochemical status of thiamine. From the above findings it was concluded that diabetic outpatients tend to have a low blood thiamine level, with low erythrocyte transketolase activity and high erythrocyte TPP effect, and showed marginal thiamine deficiency.
A sensitive assay for thiamine suitable for clinical use has been developed. It is based on precolumn oxidation of thiamine to thiochrome followed by HPLC-separation and fluorescence detection. The assay is applicable to various biological materials, including human plasma. The minimum amount detectable was 5 fmol, minimum plasma concentration 0.5 nmol/l and minimum sample volume 0.3 ml plasma. Each chromatographic run took 3 min. Inter- and intra-assay relative standard deviations (RSD) were 8.3% and 6.3%, respectively, at a stock plasma concentration of 10.8 nmol/l. At 38.8 nmol/l, interassay RSD was reduced to 3.4%. The recovery of 5 nmol/l added thiamine was 102 (SD±17)%, that of 30 nmol/l was 94±5%. Plasma levels in 91 volunteers ranged from 6.6 to 43 nmol/l, showing a log normal distribution with a median of 11.6 nmol/l. Thiamine kinetics were studied in plasma and urine from 8 men after intravenous and oral doses of 50, 100 and 200 mg thiamine hydrochloride. In all individuals, nonlinear renal elimination kinetics were demonstrated by plotting the fractional amount of thiamine excreted unchanged in urine against the corresponding area under the plasma concentration — time curve.
To assess the prevalence of thiamin deficiency in patients with congestive heart failure who are treated with diuretics that inhibit sodium and chloride reabsorption in the thick ascending limb of the loop of Henle (loop diuretic therapy). A cross-sectional investigation of thiamin status of consecutive patients with congestive heart failure being treated with loop diuretic therapy. Cardiology clinic of a midwestern tertiary-care medical center. Thirty-eight patients were recruited (mean age +/- standard deviation = 55 +/- 14 years). Validation of methodology was conducted with nine age-matched control subjects. Thiamin status was assessed biochemically by in vitro erythrocyte transketolase activity assay. Assessment of dietary intake of thiamin was accomplished with a semiquantitative food frequency questionnaire. Fisher's exact test and logistic regression were used to evaluate relationships between thiamin status and variables of interest. Biochemical evidence of thiamin deficiency was found in 8 of 38 (21%) patients. Evidence of risk for dietary thiamin inadequacy was found in 10 of 38 patients (25%). Seven of the 8 patients with biochemical evidence of thiamin deficiency met study criteria for dietary adequacy, although quantified data suggested that only 4 of the patients achieved two thirds of the Recommended Dietary Allowance. Biochemical evidence of thiamin deficiency tended to be more common among patients with poor left ventricular ejection fractions (P = .07). Thiamin deficiency may occur in a substantial proportion of patients with congestive heart failure, and dietary inadequacy may contribute to increased risk.
Thiamine deficiency results in Wernicke's encephalopathy and is commonly encountered in chronic alcoholism, gastrointestinal diseases, and HIV AIDS. The earliest metabolic consequence of thiamine deficiency is a selective loss in activity of the thiamine diphosphate-dependent enzyme alpha-ketoglutarate dehydrogenase (alpha-KGDH), a rate-limiting tricarboxylic acid cycle enzyme. Thiamine deficiency is characterized neuropathologically by selective neuronal cell death in the thalamus, pons, and cerebellum. The cause of this region-selective neuronal loss is unknown, but mechanisms involving cellular energy failure, focal lactic acidosis, and NMDA receptor-mediated excitotoxicity have classically been implicated. More recently, evidence supports a role for oxidative stress. Evidence includes increased endothelial nitric oxide synthase, nitrotyrosine deposition, microglial activation, and lipid peroxidation. Reactive oxygen species production results in decreased expression of astrocytic glutamate transporters and decreased activities of alpha-KGDH, resulting in an amplification of cell death mechanisms in thiamine deficiency.
A plasmid carrying DNA to be transcribed into a small interfering RNA against transketolase-like-1 mRNA was constructed and transfected into a human colon cancer cell line. The mRNA expression of transketolase gene family in the human colon cell line was determined by real-time polymerase chain reaction. The effect of anti-transketolase-like-1 small interfering RNA on cell proliferation and cell cycle in the human colon cancer cell line cells was detected by flow cytometry and 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyl tetrazolium bromide. The transketolase-like-1 gene was significantly downregulated in human colon cancer cell line cells transfected with small interfering RNA transketolase-like-1 constructs compared with the cells transfected with control vector and the cells without transfection. In addition, the anti-transketolase-like-1 small interfering RNA construct significantly decreased the level of transketolase in the transfected human colon cancer cell line cells, arrested them in G0/G1 phase and substantially inhibited cell proliferation. No significant difference was found in the other two genes (transketolase and transketolase-like-2 genes) between the transfected human colon cancer cell line cells and the controls (P>0.05). Our data demonstrated that the transketolase-like-1 gene plays an important role in total transketolase activity and in the cell proliferation of human colon cancer. Transketolase-like-1 may serve as a target for novel anticancer therapies.
Thiamine in diabetic nephropathy: a novel treatment modality? A Double-blind, Randomized, Placebo-controlled clinical trail on benfotiamine treatment in patients with diabetic nephropathy
  • A Alkhalaf
  • N Kleefstra
  • Kh Groenier
  • Sjl Bakker
  • G Navis
  • Bilo
Alkhalaf A, Kleefstra N, Groenier KH, Bakker SJL, Navis G, Bilo HGJ(2010). Thiamine in diabetic nephropathy: a novel treatment modality? A Double-blind, Randomized, Placebo-controlled clinical trail on benfotiamine treatment in patients with diabetic nephropathy. Diabetes Care, 33 (7): 1598-1601