AIM: Pentose phosphate pathway (PPP) with key enzyme transketolase (TKT), represents a potentially 'protective' mechanism in hyperglycaemia. Diabetic kidney disease (DKD), a common complication of both type 1 and type 2 diabetes associated with significant morbidity and mortality, represents the most common cause of chronic kidney disease (CKD). We hypothesized that protective PPP action in diabetes and eventually even more severely in concomitant DKD might be compromised by limited intracellular availability of an active TKT cofactor thiamine diphosphate (TDP). METHODS: Effect of hyperglycaemia on gene expression and protein levels of key PPP loci was studied in vitro using human cell lines relevant to diabetes (HUVEC and HRGEC) and (together with measurement of TKT activity, plasma thiamine and erythrocyte TDP concentration) in vivo in diabetic vs. non-diabetic subjects with comparable renal function (n=83 in total). RESULTS: Hyperglycaemia significantly decreased protein levels of RFC-1, THTR1, THTR2 and TKT (P<0.05) in vitro. Analysis of blood samples from CKD patients with and without diabetes and from controls did not reveal any difference in gene expression and protein levels of thiamine transporters while TKT activity and TDP in erythrocytes gradually increased with decreasing kidney function being highest in patients with CKD3-4 of both diabetic and non-diabetic aetiology. Hyperglycaemia and uremic serum mimicking CKD in diabetes did not affect TKT activity in vitro (P<0.05). CONCLUSION: Both in vitro and human experiments showed decrease or unchanged expression, respectively, of thiamine transporters induced by hyperglycaemia while TKT activity in parallel with intracellular TDP was increased in CKD patients with or without diabetes. Therefore, lack of adaptive increase of thiamine transmembrane transport allowing further increase of TKT activity might contribute to compromised PPP function in diabetes and CKD and to the development of glycotoxic injury.

• MeSH
• Biological Transport MeSH
• Renal Insufficiency, Chronic metabolism   MeSH
• Diabetes Mellitus, Type 2 metabolism   MeSH
• Diabetic Nephropathies metabolism   MeSH
• Adult MeSH
• Erythrocytes metabolism   MeSH
• Hyperglycemia metabolism   MeSH
• Middle Aged MeSH
• Humans MeSH
• Aged MeSH
• Thiamine metabolism   MeSH
• Transketolase metabolism   MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH

While the pathogenic role of dicarbonyl stress and accelerated formation of advanced glycation end products (AGEs) to glucose intolerance and to the development of diabetic complications is well established, little is known about these processes in gestational diabetes mellitus (GDM), a condition pathogenically quite similar to type 2 diabetes. The aims of the present study were (i) to determine plasma thiamine and erythrocyte thiamine diphosphate (TDP) and transketolase (TKT) activity in pregnant women with and without GDM, (ii) to assess relationships between thiamine metabolism parameters and selected clinical, biochemical and anthropometric characteristics and, finally, (iii) to analyse relationship between variability in the genes involved in the regulation of transmembrane thiamine transport (i.e. SLC19A2 and SLC19A3) and relevant parameters of thiamine metabolism. We found significantly lower plasma BMI adjusted thiamine in women with GDM (P = 0.002, Mann-Whitney) while levels of erythrocyte TDP (an active TKT cofactor) in mid-trimester were significantly higher in GDM compared to controls (P = 0.04, Mann-Whitney). However, mid-gestational TKT activity - reflecting pentose phosphate pathway activity - did not differ between the two groups (P > 0.05, Mann-Whitney). Furthermore, we ascertained significant associations of postpartum TKT activity with SNPs SLC19A2 rs6656822 and SLC19A3 rs7567984 (P = 0.03 and P = 0.007, resp., Kruskal-Wallis). Our findings of increased thiamine delivery to the cells without concomitant increase of TKT activity in women with GDM therefore indicate possible pathogenic role of thiamine mishandling in GDM. Further studies are needed to determine its contribution to maternal and/or neonatal morbidity.

• MeSH
• Adult MeSH
• Erythrocytes metabolism   MeSH
• Diabetes, Gestational blood   MeSH
• Humans MeSH
• Membrane Transport Proteins blood   MeSH
• Follow-Up Studies MeSH
• Glycation End Products, Advanced blood   MeSH
• Pregnancy MeSH
• Thiamine Pyrophosphate blood   MeSH
• Transketolase blood   MeSH
• Check Tag
• Adult MeSH
• Humans MeSH
• Pregnancy MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Clinical Trial MeSH

Besides its classical function as an orchestrator of calcium and phosphorus homeostasis, vitamin D also affects insulin secretion and tissue efficiency. A number of studies have consistently reported the inverse relationship between vitamin D deficiency and type 2 diabetes. Activation of certain metabolic pathways and down-stream transcription factors may protect from glucolipotoxicity and their targeted activation -e.g. by vitamin D - might explain the detrimental role of vitamin D deficiency in diabetes. The aim of the study was to quantify gene and protein expression of selected enzymes involved in the protection from glucolipotoxicity, specifically glyoxalase 1 (GLO1), and other enzymes with antioxidant activity - hemoxygenase (HMOX), thiamin pyrophosphokinase (TPK1) and transketolase (TKT), under normo- and hyperglycemic conditions and upon addition of vitamin D in peripheral blood mononuclear cells (PBMCs) and human umbilical vein endothelial cells (HUVEC). The results of our study indicate that the active form of vitamin D regulates gene expression of enzymes opposing the harmful effect of glucolipotoxicity whose activities appear to be suppressed by hyperglycemia. However, we were unable to confirm this effect on protein expression. While we cannot speculate on the effect of vitamin D on diabetes itself our results support its role in the protection against existing glucolipotoxicity therefore possibly translating into the prevention of development of diabetic complications.

• MeSH
• Human Umbilical Vein Endothelial Cells drug effects   enzymology   MeSH
• Homeostasis drug effects   MeSH
• Insulin secretion   MeSH
• Cells, Cultured MeSH
• Lactoylglutathione Lyase genetics   metabolism   MeSH
• Leukocytes, Mononuclear drug effects   enzymology   MeSH
• Humans MeSH
• Gene Expression Regulation MeSH
• Thiamin Pyrophosphokinase genetics   metabolism   MeSH
• Transketolase genetics   metabolism   MeSH
• Vitamin D pharmacology   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH

Naše dosavadní výsledky naznačují dysfunkci/deficit intracelulární aktivní formy thiaminu u diabetiků, která slouží jako kofaktor transketolázy – klíčového enzymu pentózového cyklu, jedné z mála metabolických drah potenciálně neutralizujících škodlivé efekty hyperglykemie. Tento “funkční“ deficit thiaminu u diabetu, především v situaci kdy je ve spojení s renálním onemocněním, může být potenciálně kritickou abnormalitou ovlivňující aktivitu pentózového cyklu a tím rozvoj diabetických komplikací. Pentózový cyklus ale může být zároveň cílem event. farmakologických intervencí. Navrhovaný projekt hodlá studovat mechanismy zodpovědné za omezenou intracelulární dostupnost aktivního thiaminu, zejména expresi membránových transportérů thiaminu a aktivitu intracelulární enzymatické aktivace jako chybějících článků v našem plném pochopení poruch thiaminového metabolismu u diabetu a chronického onemocnění ledvin.; Results of our previous study indicate dysfunction/deficit of intracellular active form of thiamine in diabetics which serves as a cofactor for transketolase - the key enzyme of pentose phosphate pathway which is considered one of the few potentially counterbalancing pathways opposing hyperglycemia effects. Ascertained functional thiamine deficiency in diabetes, especially when accompanied with advanced renal disease, could be potentially a critical abnormality influencing the activity of pentose phosphate pathway, development of diabetic complications and also target of event. pharmacologic interventions. Proposed project aims to study mechanisms responsible for limited intracellular availability of active thiamine cofactor, namely expression of thiamine membrane transporters and activity of intracellular thiamine activating and thiamine dependent enzymes as a missing links in the full understanding of altered thiamine metabolism in diabetes and chronic renal disease.

• MeSH
• Diabetes Mellitus MeSH
• Diabetic Nephropathies MeSH
• Hyperglycemia MeSH
• Diabetes Complications MeSH
• Thiamine Deficiency MeSH
• Pentose Phosphate Pathway MeSH
• Thiamine metabolism   MeSH
• Transketolase MeSH

• Conspectus
• Biochemie. Molekulární biologie. Biofyzika
• NML Fields
• biochemie
• diabetologie
• vnitřní lékařství
• NML Publication type
• závěrečné zprávy o řešení grantu IGA MZ ČR

BACKGROUND: We hypothesized that genetic variability in genes encoding enzymes metabolizing glycolytic intermediates produced in excess under hyperglycemic conditions [i.e., transketolase (TKT), transaldolase, TKT-like protein 1, fructosamine 3-kinase (FN3K), glyoxalase 1 and glucose-6-phosphate dehydrogenase] could influence progression of diabetic nephropathy (DN) and diabetes-related morbidity and mortality. METHODS: A total of 19 single nucleotide polymorphisms (SNPs) in six candidate genes were studied in 314 type 2 diabetic subjects with variable stage of kidney disease (normo- and microalbuminuria, proteinuria, end-stage renal disease). SNP selection criteria were based on known functional effect and gene coverage. SNPs were detected using polymerase chain reaction based methods. Subjects were followed up for median of 38 months. Time-to-event analysis considered three end-points: 1) DN progression by at least one stage; 2) major cardiovascular event; and 3) all-cause mortality. RESULTS: We found combined effect of TKT SNP rs11130362 and FN3K SNP rs1056534 on DN progression (p<0.01). Additionally, TKT rs3736156 alone and also in combination with the previous two SNPs exhibited significant effect on incidence of major cardiovascular events (p<0.01 and p=0.01, respectively). CONCLUSIONS: Genetic variability in rate-limiting enzymes of pathways proposed to confer hypothetical protection against hyperglycemia might act as an important determinant of hyperglycemia toxicity in long-standing diabetes.

• MeSH
• Alleles MeSH
• Diabetes Mellitus, Type 2 * enzymology   genetics   mortality   MeSH
• Diabetic Nephropathies etiology   metabolism   mortality   MeSH
• Phosphotransferases (Alcohol Group Acceptor) * genetics   MeSH
• Genotype MeSH
• Polymorphism, Single Nucleotide MeSH
• Kaplan-Meier Estimate MeSH
• Cardiovascular Diseases MeSH
• Middle Aged MeSH
• Humans MeSH
• Metabolic Networks and Pathways MeSH
• Kidney Diseases complications   MeSH
• Aged MeSH
• Severity of Illness Index MeSH
• Transketolase * genetics   MeSH
• Check Tag
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Aged MeSH
• Female MeSH

Převažující aerobní glykolýza v nádorových buňkách (tzv. Warburgův efekt) je na základě současných poznatků důsledkem přeprogramování buněčného metabolizmu během procesu maligní transformace. Regulace metabolizmu je neoddělitelnou komponentou procesu buněčné proliferace a je těsně svázána s aktivitami onkogenů a supresorových genů. Smyslem metabolické transformace nádorových buněk (a rovněž normálních intenzivně proliferujících buněk) je inkorporovat větší podíl metabolitů glukózy do nově syntetizovaných makromolekul. Mimo to aerobní glykolýza poskytuje nádorovým buňkám několik dalších selektivních výhod. Epidemio­logická data naznačují, že diabetes mellitus 2. typu je asociován s rostoucí incidencí několika typů nádorů a že mortalita v důsledku nádorových onemocnění může být ovlivněna léčbou určitými druhy anti­diabetik, nicméně další výzkum je nutný k vysvětlení toho, zda je tento vztah kauzální. Hlubší pochopení metabolizmu rychle proliferujících buněk může vést k dalšímu zlepšení protinádorové, imunosupresivní a protizánětové léčby.

The prevailing aerobic glycolysis (so called Warburg effect) in cancer cells is according to current understanding the consequence of reprogramming of cellular metabolism during the process of malignant transformation. Metabolic regulation is inseparable component of cell proliferation machinery and has a tight link with activities of oncogenes and suppressor genes. The purpose of metabolic reprogramming of cancer (but also normal intensively proliferating cells) is to incorporate greater fraction of glucose metabolites into newly synthesised macromolecules. Apart from that, aerobic glycolysis confers several other selective advantages to cancer cells. Epidemiological data indicate that type 2 diabetes mellitus is associated with increased incidence of several types of cancer and that cancer mortality can be influenced by certain types of anti-diabetic treatment, however future research is needed to explain whether this relationship might be causal. Deeper knowledge about metabolic properties of rapidly proli­ferating cells can be exploited for further improvement of anti-cancer, immunosuppressive or anti-inflammatory therapies.

• Keywords
• p53, lýtransketoláza, glyoxaláza, metabolizmus,
• MeSH
• Aerobiosis MeSH
• Diabetes Mellitus, Type 2 * complications   MeSH
• Glucose metabolism   MeSH
• Glycolysis physiology   MeSH
• Hypoglycemic Agents adverse effects   MeSH
• Humans MeSH
• Metabolic Networks and Pathways physiology   MeSH
• Metformin pharmacology   adverse effects   therapeutic use   MeSH
• Cell Transformation, Neoplastic * metabolism   MeSH
• Tumor Suppressor Protein p53 metabolism   MeSH
• Neoplasms * metabolism   MeSH
• Obesity MeSH
• Cell Proliferation MeSH
• Transketolase MeSH
• Check Tag
• Humans MeSH
• Publication type
• Research Support, Non-U.S. Gov't MeSH
• Review MeSH

BACKGROUND: Pentose phosphate pathway (PPP) represents a potentially 'protective' mechanism in hyperglycaemia due to shunting of glycolytic intermediates into PPP reactions. We hypothesized that thiamine status (plasma and erythrocyte levels of thiamine and its esters) together with genetic variability in key PPP enzymes-transketolase (TKT), transaldolase and TKT-like-might contribute to the progression of diabetic nephropathy (DN) and mortality of diabetics. METHODS: A total of 240 diabetic subjects with variable degree of kidney disease were included at baseline and were followed up for a median of 26 (IQR 21-50) months. Concentrations of thiamine in plasma and whole blood and TKT-catalysed reaction were determined by HPLC. Single-nucleotide polymorphisms (SNPs) (n = 14) were genotyped by means of PCR using TaqMan chemistry (Applied Biosystems, Foster City, CA, USA). RESULTS: Significant differences in pTh, pThDP, eryThDP and eryTKT between DN-stage groups were ascertained (P < 0.05) with advancing stage of DN being accompanied with increasing values of pTh, pThDP and eryTKT but not eryThDP. A highly significant negative correlation (r = - 0.41, P < 0.001) was found between pThDP and eryThDP, and the tertiles of the ratio of eryThDP/pThDP were significantly associated with all-cause mortality rates (P = 0.0072). We also identified significant differences in the rate of DN progression between different pTDP tertile groups (P = 0.0017). No significant genetic effects were found. CONCLUSIONS: The results support the role of 'functional' thiamine deficiency in the development of hyperglycaemia-related pathology. Limited intracellular availability of active TKT co-factor seems to be a dominant abnormality.

• MeSH
• Diabetic Nephropathies enzymology   genetics   mortality   MeSH
• Adult MeSH
• Erythrocytes enzymology   MeSH
• Genotype MeSH
• Glucose metabolism   MeSH
• Polymorphism, Single Nucleotide genetics   MeSH
• Middle Aged MeSH
• Humans MeSH
• Survival Rate MeSH
• Follow-Up Studies MeSH
• Pentosephosphates metabolism   MeSH
• Pentose Phosphate Pathway MeSH
• Cross-Sectional Studies MeSH
• Aged MeSH
• Thiamine metabolism   MeSH
• Transaldolase genetics   MeSH
• Transketolase genetics   MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

Projekt si klade za cíl pomocí genetického vyšetření variability v genech pro transketolázu a transaldolázu optimalizovat časnou diagnostiku diabetické nefropatie a umožnit individualizaci sledování diabetiků a případně i radikálnosti terapie.; The project aims to optimise early diagnostics of diabetic nephropathy by means of genetic analysis of transketolase and transaldolase genes and to allow individualised follow-up of diabetics and, eventually, even individualised therapeutic strategy.

• MeSH
• Early Diagnosis MeSH
• Diabetic Nephropathies diagnosis   MeSH
• Molecular Diagnostic Techniques MeSH
• Genetic Predisposition to Disease MeSH
• Glycolysis MeSH
• Hyperglycemia MeSH
• Diabetes Complications mortality   MeSH
• Oxidative Stress MeSH
• Polymorphism, Genetic MeSH
• Prognosis MeSH
• Transketolase MeSH
• Free Radicals MeSH

• Conspectus
• Patologie. Klinická medicína
• NML Fields
• biologie
• diabetologie
• NML Publication type
• závěrečné zprávy o řešení grantu IGA MZ ČR

Bylo zaznamenáno několik zpráv o pacientech s Wernickeovou encefalopatií, kteří se uzdravili po sníženém průtoku krve mozkem (CBF). Uvádíme případ 70letého pacienta s anamnézou dvou dnů zvýšené podrážděnosti a nemluvnosti. Při neurologickém vyšetření nebyly zjištěny žádné abnormální nálezy. Byla u něj diagnostikována Wernickeova encefalopatie, protože koncentrace tiaminu v krvi i transketoláza v erytrocytech byly nízké. SPECT odhalila snížení CBF v mnoha oblastech mozku. Po tiaminové léčbě pacient oznámil abstinenci alkoholu. O dva týdny později již nebyly žádné příznaky patrny. Jeden měsíc po nástupu obtíží byla SPECT zopakována; CBF, který byl při prvním vyšetření nižší, se vrátil na téměř normální úroveň. Tyto výsledky naznačují, že léčba tiaminem a abstinence alkoholu mohou vést k vyřešení sníženého CBF u pacientů s Wernickeovou encefalopatií, pokud nejsou neurologické příznaky vážné.

There have been few reports of recovery from reduced cerebral blood flow (CBF) in patients with Wernicke's encephalopathy. We report a 70-year-old patient with a 2-day history of increased irritability and minimal vocalisation. Neurological examination revealed no abnormal findings. He was diagnosed as having Wernicke?s encephalopathy, because both the blood thiamine concentration and erythrocyte transketolase activity were low. SPECT revealed CBF reduction in many regions of the brain. After thiamine treatment, he reported that he had abstained from alcohol. Two weeks later, all symptoms had resolved completely. SPECT was repeated one month after onset and the CBF reductions observed in the first examination had recovered to almost normal levels. These results suggest that thiamine treatment and abstinence from alcohol can result in recovery from decreased CBF in patients with Wernicke?s encephalopathy, as long as the neurological symptoms are not severe.

• MeSH
• Electroencephalography methods   utilization   MeSH
• Tomography, Emission-Computed, Single-Photon methods   utilization   MeSH
• Humans MeSH
• Evidence-Based Medicine MeSH
• Cerebrovascular Circulation MeSH
• Alcohol Drinking metabolism   prevention & control   adverse effects   MeSH
• Glucose Metabolism Disorders etiology   MeSH
• Aged MeSH
• Thiamine blood   therapeutic use   MeSH
• Transketolase blood   MeSH
• Wernicke Encephalopathy diagnosis   therapy   MeSH
• Check Tag
• Humans MeSH
• Male MeSH
• Aged MeSH
• Publication type
• Case Reports MeSH

• MeSH
• Anemia enzymology   drug therapy   MeSH
• Renal Dialysis MeSH
• Erythropoietin administration & dosage   therapeutic use   MeSH
• Peritoneal Dialysis, Continuous Ambulatory MeSH
• Humans MeSH
• Transketolase MeSH
• Drug Administration Routes MeSH
• Check Tag
• Humans MeSH
• Publication type
• Congress MeSH
• Comparative Study MeSH