Kentaro Ohtoshi

Association of -786T-C mutation of endothelial nitric oxide synthase gene with insulin resistance

Abstract Aims/hypothesis. Endothelial derived nitric oxide synthase (eNOS) gene polymorphisms affect eNOS activity and are associated with abnormal vasomotility and impaired local blood flow. A decrease in local blood flow has been reported to cause insulin resistance. The aim of this study was to examine a possible association of two eNOS polymorphisms, Glu298Asp (G894T) in exon 7 and -786T-C mutation with insulin resistance. Methods. Genotypes of both Glu298Asp and -786T-C mutation were examined by the PCR-RFLP method. Plasma nitrate and nitrite concentrations were also measured. Results. The allele frequencies of both polymorphisms showed no considerable differences in 233 non-diabetic subjects and 301 patients with Type II (non-insulin-dependent) diabetes mellitus. Non-diabetic subjects with the -786C allele had (p<0.05) higher fasting plasma insulin and homeostasis model assessment of insulin resistance than those with the -786T/ -786T genotype. Diabetic subjects with -786C allele showed higher HbA1c than those with the -786T/-786T genotype. A euglycaemic hyperinsulinemic clamp study done on 71 of the 301 patients showed a lower glucose infusion rate in diabetic patients with the -786C allele than those without it. In diabetic patients with the -786C allele, plasma nitrate and nitrite concentrations were lower than in subjects without it (p=0.026). No differences were observed between mutant carriers of Glu298Asp and non-carriers among both non-diabetic subjects and Type II diabetic patients. Conclusions/interpretation. The -786T-C mutation of the eNOS gene is associated with insulin resistance in both Japanese non-diabetic subjects and Type II diabetic patients.

A candidate gene approach to genetic contributors to the development of IgA nephropathy

BACKGROUND Genetic factors contributing to the development of IgA nephropathy remain to be elucidated. METHODS The present multicenter cross-sectional case-control study measured genotype frequencies of 65 atherosclerotic disease-related gene polymorphisms in 230 Japanese patients with IgA nephropathy and 262 apparently healthy volunteers with estimated glomerular filtration rate (eGFR) ≥60 mL/min/1.73 m(2) and negative or trace proteinuria and hematuria by dipstick test [non-chronic kidney disease (CKD) participants]. Clinical characteristics at kidney biopsy of patients with IgA nephropathy and those at the study recruitment of non-CKD participants were included as covariates in multivariate logistic regression models. RESULTS Among 31 gene polymorphisms with ≥5% of minor genotype in non-CKD participants, methionine synthase MTR A2756G (D919G) was significantly associated with IgA nephropathy using χ(2) test even after controlling for family-wise error rate by the method of Bonferroni (P = 0.044). A multivariate nonconditional logistic regression model identified MTR A2756G as a significant contributor of IgA nephropathy [2756AG and GG versus AA, odds ratio 0.42 (95% confidence interval 0.25-0.69) and 0.21 (95% confidence interval 0.06-0.68), P(trend) < 0.001]. After each patient with IgA nephropathy was randomly matched to a non-CKD participant on age (±5 years), gender, mean arterial pressure (±5 mmHg) and eGFR (±5 mL/min/1.73 m(2)), a multivariate conditional logistic regression model also verified their significant association [odds ratio 0.42 (95% confidence interval 0.18-1.00) and odds ratio 0.09 (95% confidence interval 0.01-0.73), P(trend) = 0.004]. MTR A2756G was not associated with slope of eGFR (mL/min/1.73 m(2)/year) in 230 patients with IgA nephropathy. CONCLUSION MTR A2756G was associated with the development, but not progression, of IgA nephropathy.

Rationale, Design, and Baseline Characteristics of the Utopia Trial for Preventing Diabetic Atherosclerosis Using an SGLT2 Inhibitor: A Prospective, Randomized, Open-Label, Parallel-Group Comparative Study

IntroductionSodium-glucose co-transporter-2 (SGLT2) inhibitors are anti-diabetic agents that improve glycemic control with a low risk of hypoglycemia and ameliorate a variety of cardiovascular risk factors. The aim of the ongoing study described herein is to investigate the preventive effects of tofogliflozin, a potent and selective SGLT2 inhibitor, on the progression of atherosclerosis in subjects with type 2 diabetes (T2DM) using carotid intima-media thickness (IMT), an established marker of cardiovascular disease (CVD), as a marker.MethodsThe Study of Using Tofogliflozin for Possible better Intervention against Atherosclerosis for type 2 diabetes patients (UTOPIA) trial is a prospective, randomized, open-label, blinded-endpoint, multicenter, and parallel-group comparative study. The aim was to recruit a total of 340 subjects with T2DM but no history of apparent CVD at 24 clinical sites and randomly allocate these to a tofogliflozin treatment group or a conventional treatment group using drugs other than SGLT2 inhibitors. As primary outcomes, changes in mean and maximum IMT of the common carotid artery during a 104-week treatment period will be measured by carotid echography. Secondary outcomes include changes in glycemic control, parameters related to β-cell function and diabetic nephropathy, the occurrence of CVD and adverse events, and biochemical measurements reflecting vascular function.ConclusionThis is the first study to address the effects of SGLT2 inhibitors on the progression of carotid IMT in subjects with T2DM without a history of CVD. The results will be available in the very near future, and these findings are expected to provide clinical data that will be helpful in the prevention of diabetic atherosclerosis and subsequent CVD.FundingKowa Co., Ltd.Clinical Trial RegistrationUMIN000017607.

Efficacy of liraglutide therapy in Japanese type 2 diabetic patients insufficiently controlled with basal-supported oral therapy

(J Diabetes Invest, doi: 10.1111/j.2040‐1124.2012.00223.x, 2012)