Showing papers by "Shigehiro Katayama published in 2014"

A Genome-Wide Association Study for Diabetic Retinopathy in a Japanese Population: Potential Association with a Long Intergenic Non-Coding RNA

Abstract: Elucidation of the genetic susceptibility factors for diabetic retinopathy (DR) is important to gain insight into the pathogenesis of DR, and may help to define genetic risk factors for this condition. In the present study, we conducted a three-stage genome-wide association study (GWAS) to identify DR susceptibility loci in Japanese patients, which comprised a total of 837 type 2 diabetes patients with DR (cases) and 1,149 without DR (controls). From the stage 1 genome-wide scan of 446 subjects (205 cases and 241 controls) on 614,216 SNPs, 249 SNPs were selected for the stage 2 replication in 623 subjects (335 cases and 288 controls). Eight SNPs were further followed up in a stage 3 study of 297 cases and 620 controls. The top signal from the present association analysis was rs9362054 in an intron of RP1-90L14.1 showing borderline genome-wide significance (Pmet = 1.4×10−7, meta-analysis of stage 1 and stage 2, allele model). RP1-90L14.1 is a long intergenic non-coding RNA (lincRNA) adjacent to KIAA1009/QN1/CEP162 gene; CEP162 plays a critical role in ciliary transition zone formation before ciliogenesis. The present study raises the possibility that the dysregulation of ciliary-associated genes plays a role in susceptibility to DR.

Combinations of olmesartan and a calciumchannel blocker or a diuretic inelderly hypertensive patients: A randomized, controlled trial

Abstract: Objective:The aim of the present study was to compare the cardiovascular effects of olmesartan, an angiotensin II receptor blocker, combined with a calcium channel blocker (CCB) or a diuretic, in a prospective, randomized, open-label, blinded endpoint trial.Methods:Japanese hypertensive patients age

Cohort Profile: The Japan Diabetes Complications Study: a long-term follow-up of a randomised lifestyle intervention study of type 2 diabetes

Abstract: The Japan Diabetes Complications Study, a randomised lifestyle intervention study of type 2 diabetes conducted at 59 institutes throughout Japan that enrolled 2033 eligible patients from January 1995 to March 1996, was directed at: (i) determining the incidence and progression rates of complications of diabetes; (ii) exploring clinical risk factors for complications of diabetes; and (iii) determining the association between lifestyle factors, including diet and physical activity, and complications of diabetes, in addition to comparing, in a randomised manner, the effects on type 2 diabetes of an extensive lifestyle intervention and conventional treatment. The protocol for the study originally specified four study populations according to primary outcomes, consisting of: (1) a macroangiopathy group (N = 1771); (ii) a nephropathy group (N = 1607); (iii) a retinopathy-incident group (N = 1221); and (iv) a retinopathy-progression group (N = 410). The primary outcomes were: (i) development of retinopathy; (ii) progression of retinopathy; (iii) development of overt nephropathy; and (iv) occurrence of macroangiopathic events including proven coronary heart disease and stroke. The study was originally planned to follow patients for 8 years, and an extended follow-up is ongoing. Information about primary outcomes, laboratory tests, and other clinical variables for each patient was collected at a central data centre through an annual report from each investigator. Additionally, extensive lifestyle surveys were conducted at baseline and 5 years after the beginning of the study intervention in both the intervention and conventional treatment groups. A description of the occurrence of complications of diabetes and of all-cause mortality, provided in this paper, demonstrated a clear gender-based difference in cardiovascular disease and all-cause mortality. The data set of the study is not freely available, but collaborative ideas are welcome. Potential collaborators should discuss ideas informally with the principal investigator by e-mail.

Mediobasal hypothalamic PTEN modulates hepatic insulin resistance independently of food intake in rats.

Abstract: Phosphatase and tensin homolog (PTEN) dephosphorylates phosphatidylinositol (PI) 3,4,5-triphosphate and antagonizes PI 3-kinase. Insulin acts in the mediobasal hypothalamus (MBH) to not only suppress food intake and weight gain but also improve glucose metabolism via PI 3-kinase activation. Thus, the blocking of hypothalamic PTEN is a potential target for treating obesity as well as diabetes. However, genetic modification of PTEN in specific neuronal populations in the MBH yielded complex results, and no postnatal intervention for hypothalamic PTEN has been reported yet. To elucidate how postnatal modification of hypothalamic PTEN influences food intake as well as glucose metabolism, we bidirectionally altered PTEN activity in the MBH of rats by adenoviral gene delivery. Inhibition of MBH PTEN activity reduced food intake and weight gain, whereas constitutive activation of PTEN tended to induce the opposite effects. Interestingly, the effects of MBH PTEN intervention on food intake and body weight were blunted by high-fat feeding. However, MBH PTEN blockade improved hepatic insulin sensitivity even under high-fat-fed conditions. On the other hand, constitutive activation of MBH PTEN induced hepatic insulin resistance. Hepatic Akt phosphorylation and the G6Pase expression level were modulated bidirectionally by MBH PTEN intervention. These results demonstrate that PTEN in the MBH regulates hepatic insulin sensitivity independently of the effects on food intake and weight gain. Therefore, hypothalamic PTEN is a promising target for treating insulin resistance even in states of overnutrition.

Identification of two nickel ion-induced genes, NCI16 and PcGST1, in Paramecium caudatum.

Abstract: Here, we describe the isolation of two nickel-induced genes in Paramecium caudatum, NCI16 and PcGST1, by subtractive hybridization. NCI16 encoded a predicted four-transmembrane domain protein (∼16 kDa) of unknown function, and PcGST1 encoded glutathione S-transferase (GST; ∼25 kDa) with GST and glutathione peroxidase (GPx) activities. Exposing cells to cobalt chloride also caused the moderate upregulation of NCI16 and PcGST1 mRNAs. Both nickel sulfate and cobalt chloride dose dependently induced NCI16 and PcGST1 mRNAs, but with different profiles. Nickel treatment caused a continuous increase in PcGST1 and NCI16 mRNA levels for up to 3 and 6 days, respectively, and a notable increase in H₂O₂ concentrations in P. caudatum. NCI16 expression was significantly enhanced by incubating cells with H₂O₂, implying that NCI16 induction in the presence of nickel ions is caused by reactive oxygen species (ROS). On the other hand, PcGST1 was highly induced by the antioxidant tert-butylhydroquinone (tBHQ) but not by H2O2, suggesting that different mechanisms mediate the induction of NCI16 and PcGST1. We introduced a luciferase reporter vector with an ∼0.42-kb putative PcGST1 promoter into cells and then exposed the transformants to nickel sulfate. This resulted in significant luciferase upregulation, indicating that the putative PcGST1 promoter contains a nickel-responsive element. Our nickel-inducible system also may be applicable to the efficient expression of proteins that are toxic to host cells or require temporal control.

Clinical Characteristics of Japanese Type 2 Diabetic Patients Responsive to Sitagliptin

Abstract: Japanese type 2 diabetic patients were treated with sitagliptin to evaluate the efficacy of this agent, and also to investigate the clinical characteristics of those who responded to sitagliptin. In total, 1001 diabetic patients, inadequately controlled (HbA1c ≥ 6.5%) with oral hypoglycemic agents (OHA) other than DPP-4 inhibitors or with diet and exercise only, were enrolled. We added 50mg of sitagliptin to the therapeutic regimens of 410 patients including 68 OHA naive patients, while the other 591 patients were switched from a single OHA to 50 mg of sitagliptin. After 6 months, glycemic control was significantly improved due to both reduced insulin resistance, as demonstrated by a significant HOMA-R reduction, and recovery of pancreatic β cell function, as assessed by HOMA-β and the proinsulin/insulin (PI/I) ratio. In the bivariable analysis, a good response, defined as an HbA1c reduction during the 6 months of at least 0.9%, was associated with high HbA1c and PI/I at baseline and combination treatments with sulfonylurea, biguanide and α-glucosidase inhibitors, but not with obesity. On the other hand, in the multivariable regression analysis, only high baseline HbA1c and combination treatment with anα-glucosidase inhibitor were significantly associated with a good response to sitagliptin. In patients with type 2 diabetes, the addition of sitagliptin or switching from another OHA to this agent achieved an HbA1c reduction without overloading β cells. In particular, we suggest that a good response to sitagliptin can be expected when this agent is combined with an α-glucosidase inhibitor (UMIN No. #000014157).