The APOE4 allele is associated with a decreased risk of retinopathy in type 2 diabetics.

BACKGROUND: Common polymorphisms within the apolipoprotein E (APOE) gene are suggested to be associated with the development of type 2 diabetes mellitus (T2DM), but the potential association with T2DM complications (nephropathy, neuropathy and retinopathy) remains unclear. We perform the case-control study to analyse the association between the APOE polymorphism and risk of T2DM and to analysed the potential relationship between the APOE and T2DM complications. METHODS AND RESULTS: APOE variants (rs429358 and rs7412) were genotyped by TaqMan assay in T2DM patients (N = 1274; N = 829 with complications including retinopathy, neuropathy and nephropathy status) and with PCR-RFLP in healthy nondiabetic controls (N = 2055). The comparison of subjects with genotypes associated with low plasma cholesterol (APOE2/E2 and APOE2/E3 carriers vs. others) did not show an association with T2DM (OR [95% CI] = 0.88 [0.71-1.08). The differences remained insignificant after adjusting for diabetes duration, sex and BMI. Carriers of at least one APOE4 allele (rs429358) are protected against T2DM related retinopathy (OR [95% CI] = 0.65 [0.42-0.99]. Protection against retinopathy is driven mostly by females (OR [95% CI] = 0.50 [0.25-0.99]); and remains significant (P = 0.044) after adjustment for diabetes duration and BMI. CONCLUSION: Common APOE polymorphism was not associated with T2DM in the Czech population. Yet, APOE4 allele revealed an association with retinopathy. In particular, female T2DM patients with at least one APOE4 allele exhibit lower prevalence of retinopathy in our study subjects.

Pathophysiological Implication of Vitamin D in Diabetic Kidney Disease.

BACKGROUND: Vitamin D is a hormone regulating not only calcium and phosphate homeostasis but also, at the same time, exerting many other extraskeletal functions via genomic effects (gene transcription) and probably by non-genomic effects as well. Availability is ensured by dietary intake of its precursors and by de novo production via sunlight. Yet, vitamin D deficiency and insufficiency are very common across the globe and are connected to many pathophysiological states, for example, diabetes mellitus, allergies, autoimmune diseases, pregnancy complications, and recently have also been associated with worse COVID-19 clinical outcomes. SUMMARY: In this review, we summarize current knowledge about vitamin D metabolism in general, its role in diabetes mellitus (mainly type 2) and diabetic complications (mainly diabetic kidney disease), and potential therapeutic perspectives including vitamin D signalling as a druggable target. Key Messages: Vitamin D is not only a vitamin but also a hormone involved in many physiological processes. Its insufficiency or deficiency can lead to many pathological states.

Uric Acid and Xanthine Levels in Pregnancy Complicated by Gestational Diabetes Mellitus-The Effect on Adverse Pregnancy Outcomes.

Uric acid (UA) levels are associated with many diseases including those related to lifestyle. The aim of this study was to evaluate the influence of clinical and anthropometric parameters on UA and xanthine (X) levels during pregnancy and postpartum in women with physiological pregnancy and pregnancy complicated by gestational diabetes mellitus (GDM), and to evaluate their impact on adverse perinatal outcomes. A total of 143 participants were included. Analyte levels were determined by HPLC with ultraviolet detection (HPLC-UV). Several single-nucleotide polymorphisms (SNPs) in UA transporters were genotyped using commercial assays. UA levels were higher within GDM women with pre-gestational obesity, those in high-risk groups, and those who required insulin during pregnancy. X levels were higher in the GDM group during pregnancy and also postpartum. Positive correlations between UA and X levels with body mass index (BMI) and glycemia levels were found. Gestational age at delivery was negatively correlated with UA and X levels postpartum. Postpartum X levels were significantly higher in women who underwent caesarean sections. Our data support a possible link between increased UA levels and a high-risk GDM subtype. UA levels were higher among women whose glucose tolerance was severely disturbed. Mid-gestational UA and X levels were not linked to adverse perinatal outcomes.

Deleterious Effect of Advanced CKD on Glyoxalase System Activity not Limited to Diabetes Aetiology.

Methylglyoxal production is increased in diabetes. Methylglyoxal is efficiently detoxified by enzyme glyoxalase 1 (GLO1). The aim was to study the effect of diabetic and CKD milieu on (a) GLO1 gene expression in peripheral blood mononuclear cells; (b) GLO1 protein levels in whole blood; and (c) GLO1 activity in RBCs in vivo in diabetic vs. non-diabetic subjects with normal or slightly reduced vs. considerably reduced renal function (CKD1-2 vs. CKD3-4). A total of 83 subjects were included in the study. Gene expression was measured using real-time PCR, and protein levels were quantified using Western blotting. Erythrocyte GLO1 activity was measured spectrophotometrically. GLO1 gene expression was significantly higher in subjects with CKD1-2 compared to CKD3-4. GLO1 protein level was lower in diabetics than in non-diabetics. GLO1 activity in RBCs differed between the four groups being significantly higher in diabetics with CKD1-2 vs. healthy subjects and vs. nondiabeticsfig with CKD3-4. GLO1 activity was significantly higher in diabetics compared to nondiabetics. In conclusion, both diabetes and CKD affects the glyoxalase system. It appears that CKD in advanced stages has prevailing and suppressive effects compared to hyperglycaemia. CKD decreases GLO1 gene expression and protein levels (together with diabetes) without concomitant changes of GLO1 activity.

Levels of heavy metals and their binding protein metallothionein in type 2 diabetics with kidney disease.

Hyperglycemia, a major metabolic disturbance present in diabetes, promotes oxidative stress. Activation of antioxidant defense is an important mechanism to prevent cell damage. Levels of heavy metals and their binding proteins can contribute to oxidative stress. Antiradical capacity and levels of metallothionein (MT), metals (zinc and copper), and selected antioxidants (bilirubin, cysteine, and glutathione) were determined in 70 type 2 diabetes mellitus (T2DM) subjects and 80 healthy subjects of Caucasian origin. Single nucleotide polymorphism (rs28366003) in MT gene was detected. Antiradical capacity, conjugated bilirubin, and copper were significantly increased in diabetics, whereas MT and glutathione were decreased. Genotype AA of rs28366003 was associated with higher zinc levels in the diabetic group. The studied parameters were not influenced by renal function. This is the first study comprehensively investigating differences in MT and metals relevant to oxidative stress in T2DM. Ascertained differences indicate increased oxidative stress in T2DM accompanied by abnormalities in non-enzymatic antioxidant defense systems.

Dysfunctional protection against advanced glycation due to thiamine metabolism abnormalities in gestational diabetes.

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.

Genetic variability in enzymes of metabolic pathways conferring protection against non-enzymatic glycation versus diabetes-related morbidity and mortality.

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.

Metabolic Syndrome Prevalence in Women with Gestational Diabetes Mellitus in the Second Trimester of Gravidity.

Background: Women with gestational diabetes (GDM) have an increased risk of metabolic syndrome (MS) after delivery. MS could precede gravidity. The aims of this study were (i) to detect the prevalence of MS in women at the time of GDM diagnosis, (ii) to detect the prevalence of MS in the subgroup of GDM patients with any form of impaired glucose tolerance after delivery (PGI), and (iii) to determine whether GDM women with MS have a higher risk of peripartal adverse outcomes. Methods: A cross-sectional observational study comprised n = 455 women with GDM. International Diabetes Federation (IDF) criteria for MS definition were modified to the pregnancy situation. Results: MS was detected in 22.6% of GDM patients in those with PGI 40%. The presence of MS in GDM patients was associated with two peripartal outcomes: higher incidence of pathologic Apgar score and macrosomia (p = 0.01 resp. p = 0.0004, chi-square). Conclusions: The presence of MS in GDM patients is a statistically significant risk factor (p = 0.04 chi-square) for PGI. A strong clinical implication of our findings might be to include MS diagnostics within GDM screening using modified MS criteria in the second trimester of pregnancy.

T2DM/CKD genetic risk scores and the progression of diabetic kidney disease in T2DM subjects.

This study aimed at understanding the predictive potential of genetic risk scores (GRS) for diabetic kidney disease (DKD) progression in patients with type 2 diabetes mellitus (T2DM) and Major Cardiovascular Events (MCVE) and All-Cause Mortality (ACM) as secondary outcomes. We evaluated 30 T2DM and CKD GWAS-derived single nucleotide polymorphisms (SNPs) and their association with clinical outcomes in a central European cohort (n = 400 patients). Our univariate Cox analysis revealed significant associations of age, duration of diabetes, diastolic blood pressure, total cholesterol and eGFR with progression of DKD (all P < 0.05). However, no single SNP was conclusively associated with progression to DKD, with only CERS2 and SHROOM3 approaching statistical significance. While a single SNP was associated with MCVE - WSF1 (P = 0.029), several variants were associated with ACM - specifically CANCAS1, CERS2 and C9 (all P < 0.02). Our GRS did not outperform classical clinical factors in predicting progression to DKD, MCVE or ACM. More precisely, we observed an increase only in the area under the curve (AUC) in the model combining genetic and clinical factors compared to the clinical model alone, with values of 0.582 (95 % CI 0.487-0.676) and 0.645 (95 % CI 0.556-0.735), respectively. However, this difference did not reach statistical significance (P = 0.06). This study highlights the complexity of genetic predictors and their interplay with clinical factors in DKD progression. Despite the promise of personalised medicine through genetic markers, our findings suggest that current clinical factors remain paramount in the prediction of DKD. In conclusion, our results indicate that GWAS-derived GRSs for T2DM and CKD do not offer improved predictive ability over traditional clinical factors in the studied Czech T2DM population.

NOS3 894G>T polymorphism is associated with progression of kidney disease and cardiovascular morbidity in type 2 diabetic patients: NOS3 as a modifier gene for diabetic nephropathy?

BACKGROUND/AIMS: We have previously associated SNP 894G>T in the NOS3 gene with diabetic nephropathy (DN) using multi-locus analysis. Variant 894G>T has been widely studied as a DN susceptibility factor with contradictory results. In the present study we genotyped 894G>T in the cohort of prospectively followed type 2 diabetics with the aim to investigate its possible role in the progression of DN and development of morbidity and mortality associated with diabetes. METHODS: 311 subjects with defined stage of DN were enrolled in the study and followed up for a median of 38 months. We considered three end-points: progression of DN, major cardiovascular event and all-cause mortality. RESULTS: Considering baseline GFR, age at enrolment and diabetes duration as confounders, Cox regression analysis identified 894GT genotype as a risk factor for DN progression (HR = 1.843 [95% CI 1.088 - 3.119], P = 0.023) and 894TT genotype as a risk factor for major cardiovascular event (HR = 2.515 [95% CI 1.060 - 5.965], P = 0.036). CONCLUSION: We ascertained the significant effect of the NOS3 894G>T variant on DN progression and occurrence of major cardiovascular event in T2DM subjects. Based on these results NOS3 can be considered a modifier gene for DN.

Genetic risk score is associated with T2DM and diabetes complications risks.

BACKGROUND: Type 2 diabetes mellitus (T2DM) is a prototypical complex disease with polygenic architecture playing an important role in determining susceptibility to develop the disease (and its complications) in subjects exposed to modifiable lifestyle factors. A current challenge is to quantify the degree of the individual's genetic risk using genetic risk scores (GRS) capturing the results of genome-wide association studies while incorporating possible ethnicity- or population-specific differences. METHODS: This study included three groups of T2DM (T2DM-I, N = 1,032; T2DM-II, N = 353; and T2DM-III, N = 399) patients and 2,481 diabetes-free subjects. The status of the microvascular and macrovascular diabetes complications were known for the T2DM-I patients. Overall, 21 single nucleotide polymorphisms (SNPs) were analyzed, and selected subsets were used to determine the GRS (both weighted - wGRS and unweighted - uGRS) for T2DM risk predictions (6 SNPs) and for predicting the risks of complications (7 SNPs). RESULTS: The strongest T2DM markers (P < 0.0001) were within the genes for TCF7L2 (transcription factor 7-like 2), FTO (fat mass and obesity associated protein) and ARAP1 (ankyrin repeat and PH domain 1). The T2DM-I subjects with uGRS values greater (Odds Ratio, 95 % Confidence Interval) than six had at least twice (2.00, 1.72-2.32) the risk of T2DM development (P < 0.0001), and these results were confirmed in the independent groups (T2DM-II 1.82, 1.45-2.27; T2DM-III 2.63, 2.11-3.27). The wGRS (>0.6) further improved (P < 0.000001) the risk estimations for all three T2DM groups. The uGRS was also a significant predictor of neuropathy (P < 0.0001), nephropathy (P < 0.005) and leg ischemia (P < 0.0005). CONCLUSIONS: If carefully selected and specified, GRS, both weighted and unweighted, could be significant predictors of T2DM development, as well as the diabetes complications development.

ADMA, SDMA and L-arginine/ADMA ratio but not DDAH genetic polymorphisms are reliable predictors of diabetic nephropathy progression as identified by competing risk analysis.

BACKGROUND/AIMS: Complex interplay of genetic and (patho)physiological factors influence availability of nitric oxide during the development and progression of diabetic complications. We assessed predictive value of commonly studied methylated asymmetric and symmetric dimethylarginines (ADMA and SDMA) and selected single nucleotide polymorphisms (SNPs) in dimethylarginine dimethylaminohydrolase (DDAH) 1 and 2 genes for the progression of diabetic nephropathy (DN). METHODS: A total of 341 type 1 and type 2 diabetes patients with variable degree of kidney disease were included at baseline. Plasma levels of ADMA, SDMA and L-arginine were measured and six tagging SNPs in DDAH1 and 2 were determined. Progression of DN was defined as a transition from any given stage to a more advanced stage of albuminuria. Competing risk analysis was applied. RESULTS: Plasma levels of ADMA and SDMA significantly correlated with GFR. No significant genotype-phenotype relationship was ascertained for ADMA and DDAH variants, but SNP rs805304 exhibited marginally significant association with DN. ADMA, SDMA and L-arginine/ADMA ratio standardised to GFR were identified as significant predictors of DN progression but not GFR decline using multivariate competing risk analysis. CONCLUSIONS: In our study we confirmed potentially significant role of ADMA and SDMA for the assessment of risk of DN progression in European diabetic population.

Role of thiamine status and genetic variability in transketolase and other pentose phosphate cycle enzymes in the progression of diabetic nephropathy.

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.

Development of a New Risk Score for Stratification of Women with Gestational Diabetes Mellitus at High Risk of Persisting Postpartum Glucose Intolerance Using Routinely Assessed Parameters.

The aims of the study were (i) to find predictive factors for early postpartum conversion of gestational diabetes mellitus (GDM) into persisting glucose intolerance (PGI), (ii) to evaluate potential differences in adverse perinatal outcomes in GDM women with and without early postpartum PGI and, finally, (iii) to establish a risk score to predict postpartum PGI. A cross-sectional study comprised 244 GDM patients with known age, parity, positive family history of diabetes, pre-gestational BMI, comorbidities, smoking history, results of mid-trimester oral glucose tolerance test, HbA1c, obstetric complications, neonatal outcomes and mode of delivery. A risk score was calculated using parameters with highest odds ratios in a statistic scoring model. Significant differences between women with and without PGI postpartum were ascertained for mid-trimester fasting plasma glucose (p < 0.001), HbA1c above 42 mmol/mol (p = 0.035), prevalence of obesity (p = 0.007), hypothyroidism, family history of diabetes and smoking. We also observed higher incidence of prolonged and complicated delivery in PGI group (p = 0.04 and 0.007, respectively). In conclusion, this study identified several parameters with predictive potential for early PGI and also adverse peripartal outcomes. We established a simple risk-stratification score for PGI prediction applicable for GDM affected women prior their leaving maternity ward. Yet, given a relatively small sample size as a main limitation of this study, the proposed score should be validated in the larger cohort.

High perioperative level of oxidative stress as a prognostic tool for identifying patients with a high risk of recurrence of head and neck squamous cell carcinoma.

BACKGROUND: The aim of the study was to investigate the relationships among (a) glutathione peroxidase (GPx) and malondialdehyde (MDA); (b) oncological characteristics (i.e., TNM classification, tumor grade), and; (c) prognosis of head and neck squamous cell carcinoma. METHODS: In a prospective cohort study, we followed 88 patients for 67.4 months (median 40.3) after surgery for head and neck squamous cell carcinoma. Activity of GPx was determined by ELISA and plasma MDA concentration by liquid chromatography. RESULTS: Lower GPx activity was observed in the T3/4 patients than in the T1/2 group. Tumor grade was significantly correlated with both GPx (P = 0.001) and MDA (P = 0.05, both Spearman). The perioperative level of MDA was higher in patients who later recurred during the follow-up period (n = 15) than in the complete remission group (P = 0.01, Mann-Whitney). Median disease-free interval and overall survival in the group with MDA > median were 29.5 and 32.0 months, respectively, and 38.4 and 40.3 months in the patient group with MDA ≤ median (P = 0.10 and P = 0.08, respectively; Kaplan-Meier). Patients with MDA levels higher than the median had a more than twofold greater risk of recurrence than patients with MDA levels smaller than the median (31.3 vs. 15.2%, P = 0.06, logrank). CONCLUSION: Our results suggest that an increased MDA level at the time of initial surgery is found in patients with a high risk of recurrence, which suggests that each patient can be categorized according to risk of recurrence based on their MDA level at the time of initial surgery.

Metformin in Oncology - How Far Is Its Repurposing as an Anticancer Drug?

BACKGROUND: Metformin is the most commonly used antidiabetic drug with a plethora of proven metabolic and cardiovascular beneficial effects and exceptional safety profile. On top of the established metabolic effects, retrospective epidemiologic evidence shows that metformin use is associated with decreased cancer risk and/or improved disease prognosis in diabetic cancer patients on metformin compared to those treated with different antidiabetic drugs. This is a sound argument for eventual repurposing metformin as an adjuvant drug in oncology; however, evidence-based data are currently needed to establish this. Metformin is a biguanide that in the context of type 2 diabetes primarily targets the liver. Metformin inhibits oxidative phosphorylation which leads to the suppression of gluconeogenesis and causes decrease of blood glucose concentration. Mechanisms responsible for metformin anti-neoplastic effect have been investigated extensively, and key events seem to centralize around its ability to induce intracellular energetic stress with subsequent changes of metabolism resulting in cytostatic or cytotoxic action. Large clinical experience with metformin in the treatment of diabetes together with its plausible effects on different cancer cell types initiated a number of clinical trials that tested the hypothesis that metformin might have a beneficial effect in the treatment of cancer. PURPOSE: The aim of this review is to compile recent advances in our understanding of metformin antineoplastic effects and to give a summary of the results of recent clinical trials of metformin for treatment of different cancer types.

Transketolase Activity but not Thiamine Membrane Transport Change in Response to Hyperglycaemia and Kidney Dysfunction.

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.

HFE C282Y gene variant is a risk factor for the progression to decompensated liver disease in chronic viral hepatitis C subjects in the Czech population.

AIM: To determine the prevalence of selected HFE polymorphisms (C282Y, H63D and S65C) among patients with chronic viral hepatitis B and C and to investigate their role in the progression of liver disease. METHODS: A total of 207 subjects with chronic B or C viral hepatitis and 243 healthy controls were enrolled in the case-control study. Cases were further classified into three groups according to the clinical stage of liver disease: (A) virus carriers; (B) compensated liver disease; and (C) decompensated liver disease. HFE polymorphisms were detected by polymerase chain reaction-based methodology. Fisher's exact test, chi(2) and Kruskal-Wallis tests were used to test for differences in variables studied between groups. Haplotypes were inferred in silico and their distribution compared by permutation test. Modified survival (time-to-event) analysis was used to test for the differences in the progression to the decompensated liver disease in carriers of C282Y wild-type versus mutated genotypes. RESULTS: The frequency of HFE genotypes, alleles and haplotypes differed neither between HBV nor HCV patients versus controls. In HCV subjects: (i) the frequency of the 282Y allele was significantly higher in the (C) group compared to (B) group (12.5 vs 2.2%, respectively, P = 0.002, Fisher's exact test); and (ii) carriers of the 282Y mutation exhibited significantly faster progression to decompensated liver disease than wild-type carriers (P = 0.044, log-rank test). CONCLUSION: Carriage of the minor HFE C282Y polymorphism is associated with decompensated liver disease and its earlier onset in the subjects with chronic viral hepatitis C in the Czech population.

1,25-Dihydroxyvitamin D increases the gene expression of enzymes protecting from glucolipotoxicity in peripheral blood mononuclear cells and human primary endothelial cells.

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.

Effect of glucose variability on pathways associated with glucotoxicity in diabetes: Evaluation of a novel in vitro experimental approach.

AIMS: Glycaemic variability (GV) has been hypothesized to increase the risk of diabetes complications; however, results of clinical studies are contradictory. The effect of GV on cell phenotypes has been investigated in vitro showing that GV may have more deleterious effect on cells that high glucose itself. However, methodology used to study GV in vitro differs significantly between studies and does not reflect in vivo situation. Therefore we aimed to establish clinically relevant an in vitro experimental approach for the study of GV that reflects intra-day glucose fluctuations of subjects with type 1 diabetes mellitus (T1DM) and of healthy subjects and to test how low and high GV affect expression of genes that protects cells from hyperglycaemia-induced damage. METHODS: Human umbilical vein endothelial cells (HUVEC) were cultured 24h in medium with different glucose profiles: high GV, low GV and GV of healthy subjects-profiles created according to CGM of T1DM patients and healthy subjects. These profiles were compared to commonly used 5.5 and 25mmol/l glucose concentrations. Gene expression was determined using quantitative PCR. RESULTS: Our results showed general down-regulation of enzymes that are involved in the protection against hyperglycaemia-induced intracellular changes in both low and high GV compared to normal glycaemia similarly to the decrease induced by continuous hyperglycaemia. Gene expressions did not differ between high and low GV. CONCLUSION: Our data indicate that GV may have similar or even greater effect than continuous hyperglycaemia on the expression of several genes relevant to pathogenesis of diabetes microvascular complications.