Transcriptional silencing in yeast provides a genetically tractable system for analyzing the formation and maintenance of heterochromatin, a transcriptionally repressive chromatin structure found in all organisms. The nucleosome constitutes the central structure of chromatin and comprises two chains each of histones H2A, H2B, H3 and H4. The structure of the nucleosome consists of a central globular core surrounded by outwardly protruding amino-terminal histone tails. We show that a specific surface of the assembled nucleosome core is required for silencing in yeast. This surface is located at a H3/H4 histone-fold motif and contains amino-acid side chains located on the nucleosome disk surface and on an adjacent surface that interacts with DNA. The side chains, identified from mutants in which all three forms of silencing (rDNA, telomere and silent mating locus silencing) are eliminated, are centered around Lys79 of histone H3, a residue methylated by the yeast Dot1 protein. Moreover, mutations in the genes encoding H3 (HHT1 and HHT2) and H4 (HHF1 and HHF2) mapping to spatially adjacent amino-acid residues affected the three forms of silencing distinctly, suggesting that specific interactions mediate each form of silencing. Several of the mutations that we identified resemble those in a cluster of previously identified mutations affecting a distinct histone-fold motif elsewhere in the nucleosome core. These two clusters relieve distinct forms of transcriptional repression (silencing versus repression resulting from lack of Swi/Snf chromatin remodeling activity).
ObjectiveThe aim of this study was to assess the glucose-lowering and lipid-modifying effects, and safety profile of lobeglitazone, a novel peroxisome proliferator-activated receptor- γ agonist, compared to placebo as a monotherapy in patients with type 2 diabetes.Research Design and MethodsIn this 24-week, multicenter, randomized, double-blind, parallel-group, placebo controlled study, 173 patients were randomly assigned (a 2∶1 ratio) to lobeglitazone 0.5 mg (n = 115) or matching placebo (n = 58) orally once daily. The primary endpoint was the change in glycated hemoglobin (HbA1c) from baseline to the end of treatment. The secondary endpoints included various glycemic parameters, lipid parameters and safety profile (ClinicalTrials.gov number NCT01001611).ResultsAt 24 weeks, a significant reduction in HbA1c was observed with lobeglitazone versus placebo (−0.44% vs 0.16%, mean difference −0.6%, p<0.0001). The goal of HbA1c <7% was achieved significantly more in the lobeglitazone group compared to the placebo group (44% vs 12%, p<0.0001). Markers of insulin resistance were also improved in the lobeglitazone group. In addition, lobeglitazone treatment significantly improved triglycerides, high density lipoprotein cholesterol, small dense low density lipoprotein cholesterol, free fatty acid, and apolipoprotein-B/CIII compared to placebo (p<0.01, respectively). More weight gain was observed in the lobeglitazone group than the placebo group (0.89 kg vs – 0.63 kg, mean difference 1.52 kg, p<0.0001). The safety profile was comparable between the two groups and lobeglitazone was well tolerated.ConclusionsLobeglitazone 0.5 mg showed a favorable balance in the efficacy and safety profile. The results support a potential role of lobeglitazone in treating type 2 diabetes.Trial RegistrationClinicaltrials.gov NCT01001611
Background: The aim of the present 24-week multicentre randomized noninferiority trial was to compare the efficacy and safety of two insulin intensification strategies in uncontrolled type 2 diabetes despite optimized basal insulin therapy. Methods: Patients with fasting plasma glucose (FPG) <130 mg/dL and HbA1c 7.0%-10.0% while on insulin glargine were randomized to a basalprandial group (stepwise addition of insulin glulisine) or a premixed insulin group (insulin aspart/insulin aspart protamine 30/70 starting with 6 IU twice daily). The primary endpoint was the change in HbA1c after 24 weeks (noninferiority margin 0.4%). Results: At Week 24, the adjusted mean change from baseline HbA1c was -0.94 ± 0.09% and -1.04 ± 0.09% in basal-prandial and premixed insulin groups, respectively, with a mean difference of -0.09% (95% confidence interval [CI] -0.35, 0.16). A lower rate of hypoglycemia with a similar reduction in HbA1c was observed during stabilization of the total daily insulin dose in the premixed insulin group (Weeks 0-12). After stabilization of the total daily insulin dose, the rate of hypoglycemia and the total daily insulin dose were similar in the two groups. Conclusions: The efficacy and safety of the two intensifying regimens were similar after stabilization of the total daily insulin dose when oral agents were maintained. Starting with a lower total daily insulin dose with a gradual change in the treatment regimen was helpful in reducing the rate of hypoglycemia during initial stabilization of the total daily insulin dose.
There are many studies on the prevalence, clinical characteristics, and economic burden of diabetes across the past four decades in Korea. Nonetheless, there is a dearth of nationwide study regarding diabetes encompassing all age group. Eight years ago, the Committee on the Epidemiology of Diabetes Mellitus of Korean Diabetes Association collaborated with Health Insurance Review & Assessment Service to evaluate the status of diabetes care and characteristics in diabetic patients in Korea. In 2007, the collaborative task force team published a comprehensive survey titled "Diabetes in Korea 2007." In this review, we reappraise the diabetic epidemics from the joint report and suggest further studies that are needed to be investigated in the future.
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