bluuebunny/crossref_metadata_2025_split huggingface dataset:
Resveratrol Improves Oxidative Stress and Protects Against Diabetic Nephropathy Through Normalization of Mn-SOD Dysfunction in AMPK/SIRT1-Independent Pathway
Authors: Kitada Munehiro , Kume Shinji , Imaizumi Noriko , Koya Daisuke 
Published: January 2011

OBJECTIVE
Despite the beneficial effects of resveratrol (RSV) on cardiovascular disease and life span, its effects on type 2 diabetic nephropathy remain unknown. This study examined the renoprotective effects of RSV in db/db mice, a model of type 2 diabetes.

RESEARCH DESIGN AND METHODS
db/db mice were treated with RSV (0.3% mixed in chow) for 8 weeks. We measured urinary albumin excretion (UAE), histological changes (including mesangial expansion, fibronectin accumulation, and macrophage infiltration), oxidative stress markers (urinary excretion and mitochondrial content of 8-hydroxy-2'-deoxyguanosine [8-OHdG], nitrotyrosine expression), and manganese-superoxide dismutase (Mn-SOD) activity together with its tyrosine-nitrated modification and mitochondrial biogenesis in the kidney. Blood glucose, glycated hemoglobin, and plasma lipid profiles were also measured. The phosphorylation of 5′-AMP–activated kinase (AMPK) and expression of silent information regulator 1 (SIRT1) in the kidney were assessed by immunoblotting.

RESULTS
RSV significantly reduced UAE and attenuated renal pathological changes in db/db mice. Mitochondrial oxidative stress and biogenesis were enhanced in db/db mice; however, Mn-SOD activity was reduced through increased tyrosine-nitrated modification. RSV ameliorated such alterations and partially improved blood glucose, glycated hemoglobin, and abnormal lipid profile in db/db mice. Activation of AMPK was decreased in the kidney of db/db mice compared with db/m mice. RSV neither modified AMPK activation nor SIRT1 expression in the kidney.

CONCLUSIONS
RSV ameliorates renal injury and enhanced mitochondrial biogenesis with Mn-SOD dysfunction in the kidney of db/db mice, through improvement of oxidative stress via normalization of Mn-SOD function and glucose-lipid metabolism. RSV has antioxidative activities via AMPK/SIRT1-independent pathway.
Glucagon Receptor Knockout Prevents Insulin-Deficient Type 1 Diabetes in Mice
Authors: Lee Young , Wang May-Yun , Du Xiu Quan , Charron Maureen J. , Unger Roger H. 
Published: January 2011

OBJECTIVE
To determine the role of glucagon action in the metabolic phenotype of untreated insulin deficiency.

RESEARCH DESIGN AND METHODS
We compared pertinent clinical and metabolic parameters in glucagon receptor-null (Gcgr−/−) mice and wild-type (Gcgr+/+) controls after equivalent destruction of β-cells. We used a double dose of streptozotocin to maximize β-cell destruction.

RESULTS
Gcgr+/+ mice became hyperglycemic (&gt;500 mg/dL), hyperketonemic, polyuric, and cachectic and had to be killed after 6 weeks. Despite comparable β-cell destruction in Gcgr−/− mice, none of the foregoing clinical or laboratory manifestations of diabetes appeared. There was marked α-cell hyperplasia and hyperglucagonemia (∼1,200 pg/mL), but hepatic phosphorylated cAMP response element binding protein and phosphoenolpyruvate carboxykinase mRNA were profoundly reduced compared with Gcgr+/+ mice with diabetes—evidence that glucagon action had been effectively blocked. Fasting glucose levels and oral and intraperitoneal glucose tolerance tests were normal. Both fasting and nonfasting free fatty acid levels and nonfasting β-hydroxy butyrate levels were lower.

CONCLUSIONS
We conclude that blocking glucagon action prevents the deadly metabolic and clinical derangements of type 1 diabetic mice.
SUMOylation Regulates Insulin Exocytosis Downstream of Secretory Granule Docking in Rodents and Humans
Authors: Dai Xiao-Qing , Plummer Greg , Casimir Marina , Kang Youhou , Hajmrle Catherine , Gaisano Herbert Y. , Manning Fox Jocelyn E. , MacDonald Patrick E. 
Published: January 2011

OBJECTIVE
The reversible attachment of small ubiquitin-like modifier (SUMO) proteins controls target localization and function. We examined an acute role for the SUMOylation pathway in downstream events mediating insulin secretion.

RESEARCH DESIGN AND METHODS
We studied islets and β-cells from mice and human donors, as well as INS-1 832/13 cells. Insulin secretion, intracellular Ca2+, and β-cell exocytosis were monitored after manipulation of the SUMOylation machinery. Granule localization was imaged by total internal reflection fluorescence and electron microscopy; immunoprecipitation and Western blotting were used to examine the soluble NSF attachment receptor (SNARE) complex formation and SUMO1 interaction with synaptotagmin VII.

RESULTS
SUMO1 impairs glucose-stimulated insulin secretion by blunting the β-cell exocytotic response to Ca2+. The effect of SUMO1 to impair insulin secretion and β-cell exocytosis is rapid and does not require altered gene expression or insulin content, is downstream of granule docking at the plasma membrane, and is dependent on SUMO-conjugation because the deSUMOylating enzyme, sentrin/SUMO-specific protease (SENP)-1, rescues exocytosis. SUMO1 coimmunoprecipitates with the Ca2+ sensor synaptotagmin VII, and this is transiently lost upon glucose stimulation. SENP1 overexpression also disrupts the association of SUMO1 with synaptotagmin VII and mimics the effect of glucose to enhance exocytosis. Conversely, SENP1 knockdown impairs exocytosis at stimulatory glucose levels and blunts glucose-dependent insulin secretion from mouse and human islets.

CONCLUSIONS
SUMOylation acutely regulates insulin secretion by the direct and reversible inhibition of β-cell exocytosis in response to intracellular Ca2+ elevation. The SUMO protease, SENP1, is required for glucose-dependent insulin secretion.
Smad3 Deficiency in Mice Protects Against Insulin Resistance and Obesity Induced by a High-Fat Diet
Authors: Tan Chek Kun , Leuenberger Nicolas , Tan Ming Jie , Yan Yew Wai , Chen Yinghui , Kambadur Ravi , Wahli Walter , Tan Nguan Soon 
Published: January 2011

OBJECTIVE
Obesity and associated pathologies are major global health problems. Transforming growth factor-β/Smad3 signaling has been implicated in various metabolic processes, including adipogenesis, insulin expression, and pancreatic β-cell function. However, the systemic effects of Smad3 deficiency on adiposity and insulin resistance in vivo remain elusive. This study investigated the effects of Smad3 deficiency on whole-body glucose and lipid homeostasis and its contribution to the development of obesity and type 2 diabetes.

RESEARCH DESIGN AND METHODS
We compared various metabolic profiles of Smad3-knockout and wild-type mice. We also determined the mechanism by which Smad3 deficiency affects the expression of genes involved in adipogenesis and metabolism. Mice were then challenged with a high-fat diet to study the impact of Smad3 deficiency on the development of obesity and insulin resistance.

RESULTS
Smad3-knockout mice exhibited diminished adiposity with improved glucose tolerance and insulin sensitivity. Chromatin immunoprecipitation assay revealed that Smad3 deficiency increased CCAAT/enhancer-binding protein β-C/EBP homologous protein 10 interaction and exerted a differential regulation on proliferator-activated receptor β/δ and proliferator-activated receptor γ expression in adipocytes. Focused gene expression profiling revealed an altered expression of genes involved in adipogenesis, lipid accumulation, and fatty acid β-oxidation, indicative of altered adipose physiology. Despite reduced physical activity with no modification in food intake, these mutant mice were resistant to obesity and insulin resistance induced by a high-fat diet.

CONCLUSIONS
Smad3 is a multifaceted regulator in adipose physiology and the pathogenesis of obesity and type 2 diabetes, suggesting that Smad3 may be a potential target for the treatment of obesity and its associated disorders.
Induction of Mixed Chimerism With MHC-Mismatched but Not Matched Bone Marrow Transplants Results in Thymic Deletion of Host-Type Autoreactive T-Cells in NOD Mice
Authors: Racine Jeremy , Wang Miao , Zhang Chunyan , Lin Chia-Lei , Liu Hongjun , Todorov Ivan , Atkinson Mark , Zeng Defu 
Published: January 2011

OBJECTIVEInduction of mixed or complete chimerism via hematopoietic cell transplantation (HCT) from nonautoimmune donors could prevent or reverse type 1 diabetes (T1D). In clinical settings, HLA-matched HCT is preferred to facilitate engraftment and reduce the risk for graft versus host disease (GVHD). Yet autoimmune T1D susceptibility is associated with certain HLA types. Therefore, we tested whether induction of mixed chimerism with major histocompatibility complex (MHC)-matched donors could reverse autoimmunity in the NOD mouse model of T1D.RESEARCH DESIGN AND METHODSPrediabetic wild-type or transgenic BDC2.5 NOD mice were conditioned with a radiation-free GVHD preventative anti-CD3/CD8 conditioning regimen and transplanted with bone marrow (BM) from MHC-matched or mismatched donors to induce mixed or complete chimerism. T1D development and thymic deletion of host-type autoreactive T-cells in the chimeric recipients were evaluated.RESULTSInduction of mixed chimerism with MHC-matched nonautoimmune donor BM transplants did not prevent T1D in wild-type NOD mice, although induction of complete chimerism did prevent the disease. However, induction of either mixed or complete chimerism with MHC-mismatched BM transplants prevented T1D in such mice. Furthermore, induction of mixed chimerism in transgenic BDC2.5-NOD mice with MHC-matched or -mismatched MHC II−/− BM transplants failed to induce thymic deletion of de novo developed host-type autoreactive T-cells, whereas induction of mixed chimerism with mismatched BM transplants did.CONCLUSIONSInduction of mixed chimerism with MHC-mismatched, but not matched, donor BM transplants re-establishes thymic deletion of host-type autoreactive T-cells and prevents T1D, with donor antigen-presenting cell expression of mismatched MHC II molecules being required.
Distinct Roles of Endothelial and Adipocyte Caveolin-1 in Macrophage Infiltration and Adipose Tissue Metabolic Activity
Authors: Briand Nolwenn , Le Lay Soazig , Sessa William C. , Ferré Pascal , Dugail Isabelle 
Published: January 2011

OBJECTIVE
Defective caveolin-1 expression is now recognized as a cause of lipoatrophic diabetes in patients, due to primary caveolin gene mutations or secondary caveolin deficiency caused by PTRF/cavin gene defects. The goal of this study was to establish the relative contribution of endothelial cells and adipocytes, both highly expressing caveolin-1 to the lipoatrophic phenotype of mice with global caveolin-1 gene invalidation (Cav1-KO).

RESEARCH DESIGN AND METHODS
We compared adipose tissue development and metabolic phenotype of wild-type (WT), lipoatrophic Cav1-KO, and a murine model with specific rescue of caveolin-1 expression in endothelial cells (caveolin-1-reconstituted [Cav1-RC]).

RESULTS
Defective adipose tissue development, reduced adipocyte size, and global alteration in adipose tissue gene expression that characterize lipoatrophic caveolin-1 null mice were still observed in Cav1-RC, indicating a prominent role of adipocyte-derived caveolin in lipoatrophy. We also observed that Cav1-KO adipose tissue contained an increased proportion of infiltrated macrophages compared with control mice, mostly with an alternate activation M2 phenotype. In contrast with defective lipid storage and lipoatrophy, macrophage infiltration was normalized in Cav1-RC mice, pointing to caveolin-1-dependent endothelium permeability as the causing factor for adipose tissue macrophage infiltration in this model.

CONCLUSIONS
This is the first report of a specific role for adipocyte caveolin expression in lipid storage. Our study also shows that endothelium caveolin critically participates in the control of macrophage extravasation from the blood into adipose tissue, therefore establishing distinct roles depending on topology of caveolin expression in different cell types of adipose tissue.
Effects of Insulin on Brain Glucose Metabolism in Impaired Glucose Tolerance
Authors: Hirvonen Jussi , Virtanen Kirsi A. , Nummenmaa Lauri , Hannukainen Jarna C. , Honka Miikka-Juhani , Bucci Marco , Nesterov Sergey V. , Parkkola Riitta , Rinne Juha , Iozzo Patricia , Nuutila Pirjo 
Published: January 2011

OBJECTIVE
Insulin stimulates brain glucose metabolism, but this effect of insulin is already maximal at fasting concentrations in healthy subjects. It is not known whether insulin is able to stimulate glucose metabolism above fasting concentrations in patients with impaired glucose tolerance.

RESEARCH DESIGN AND METHODS
We studied the effects of insulin on brain glucose metabolism and cerebral blood flow in 13 patients with impaired glucose tolerance and nine healthy subjects using positron emission tomography (PET). All subjects underwent PET with both [18F]fluorodeoxyglucose (for brain glucose metabolism) and [15O]H2O (for cerebral blood flow) in two separate conditions (in the fasting state and during a euglycemic-hyperinsulinemic clamp). Arterial blood samples were acquired during the PET scans to allow fully quantitative modeling.

RESULTS
The hyperinsulinemic clamp increased brain glucose metabolism only in patients with impaired glucose tolerance (whole brain: +18%, P = 0.001) but not in healthy subjects (whole brain: +3.9%, P = 0.373). The hyperinsulinemic clamp did not alter cerebral blood flow in either group.

CONCLUSIONS
We found that insulin stimulates brain glucose metabolism at physiological postprandial levels in patients with impaired glucose tolerance but not in healthy subjects. These results suggest that insulin stimulation of brain glucose metabolism is maximal at fasting concentrations in healthy subjects but not in patients with impaired glucose tolerance.
Rictor/mTORC2 Is Essential for Maintaining a Balance Between β-Cell Proliferation and Cell Size
Authors: Gu Yanyun , Lindner Jill , Kumar Anil , Yuan Weiping , Magnuson Mark A. 
Published: January 2011

OBJECTIVE
We examined the role of Rictor/mammalian target of rapamycin complex 2 (mTORC2), a key component of the phosphotidylinositol-3-kinase (PI3K)/mTORC2/AKT signaling pathway, in regulating both β-cell mass and function.

RESEARCH DESIGN AND METHODS
Mice with β-cell–specific deletions of Rictor or Pten were studied to determine the effects of deleting either or both genes on β-cell mass and glucose homeostasis.

RESULTS
Rictor null mice exhibited mild hyperglycemia and glucose intolerance caused by a reduction in β-cell mass, β-cell proliferation, pancreatic insulin content, and glucose-stimulated insulin secretion. Islets from these mice exhibited decreased AKT-S473 phosphorylation and increased abundance of FoxO1 and p27 proteins. Conversely, Pten null (βPtenKO) mice exhibited an increase in β-cell mass caused by increased cellular proliferation and size. Although β-cell mass was normal in mice lacking both Rictor and Pten (βDKO), their β-cells were larger than those in the βPtenKO mice. Even though the β-cell proliferation rate in the βDKO mice was lower than in the βPtenKO mice, there was a 12-fold increase the phosphorylation of AKT-T308.

CONCLUSIONS
PI3K/AKT signaling through mTORC2/pAKT-S473 plays a key role in maintaining normal β-cell mass. The phosphorylation of AKT-S473, by negatively regulating that of AKT-T308, is essential for maintaining a balance between β-cell proliferation and cell size in response to proliferative stimuli.
Tests for Genetic Interactions in Type 1 Diabetes
Authors: Morahan Grant , Mehta Munish , James Ian , Chen Wei-Min , Akolkar Beena , Erlich Henry A. , Hilner Joan E. , Julier Cécile , Nerup Jørn , Nierras Concepcion , Pociot Flemming , Todd John A. , Rich Stephen S. ,   for the Type 1 Diabetes Genetics Consortium
Published: January 2011

OBJECTIVE
Interactions between genetic and environmental factors lead to immune dysregulation causing type 1 diabetes and other autoimmune disorders. Recently, many common genetic variants have been associated with type 1 diabetes risk, but each has modest individual effects. Familial clustering of type 1 diabetes has not been explained fully and could arise from many factors, including undetected genetic variation and gene interactions.

RESEARCH DESIGN AND METHODS
To address this issue, the Type 1 Diabetes Genetics Consortium recruited 3,892 families, including 4,422 affected sib-pairs. After genotyping 6,090 markers, linkage analyses of these families were performed, using a novel method and taking into account factors such as genotype at known susceptibility loci.

RESULTS
Evidence for linkage was robust at the HLA and INS loci, with logarithm of odds (LOD) scores of 398.6 and 5.5, respectively. There was suggestive support for five other loci. Stratification by other risk factors (including HLA and age at diagnosis) identified one convincing region on chromosome 6q14 showing linkage in male subjects (corrected LOD = 4.49; replication P = 0.0002), a locus on chromosome 19q in HLA identical siblings (replication P = 0.006), and four other suggestive loci.

CONCLUSIONS
This is the largest linkage study reported for any disease. Our data indicate there are no major type 1 diabetes subtypes definable by linkage analyses; susceptibility is caused by actions of HLA and an apparently random selection from a large number of modest-effect loci; and apart from HLA and INS, there is no important susceptibility factor discoverable by linkage methods.
Serum Apolipoprotein AI and B Are Stronger Biomarkers of Diabetic Retinopathy Than Traditional Lipids
Authors: Sasongko Muhammad Bayu , Wong Tien Y. , Nguyen Thanh T. , Kawasaki Ryo , Jenkins Alicia , Shaw Jonathan , Wang Jie Jin 
Published: January 2011

OBJECTIVE
To describe and compare the associations of serum lipoproteins and apolipoproteins with diabetic retinopathy.

RESEARCH DESIGN AND METHODS
This was a cross-sectional study of 224 diabetic patients (85 type 1 and 139 type 2) from a diabetes clinic. Diabetic retinopathy was graded from fundus photographs according to the Airlie House Classification system and categorized into mild, moderate, and vision-threatening diabetic retinopathy (VTDR). Serum traditional lipids (total, LDL, non–HDL, and HDL cholesterol and triglycerides) and apolipoprotein AI (apoAI), apolipoprotein B (apoB), and the apoB-to-apoAI ratio were assessed.

RESULTS
Diabetic retinopathy was present in 133 (59.4%) individuals. After adjustment for age, sex, diabetes duration, A1C, systolic blood pressure, and diabetes medications, the HDL cholesterol level was inversely associated with diabetic retinopathy (odds ratio 0.39 [95% CI 0.16–0.94], highest versus lowest quartile; Ptrend = 0.017). The ApoAI level was inversely associated with diabetic retinopathy (per SD increase, 0.76 [95% CI 0.59–0.98]), whereas apoB (per SD increase, 1.31 [1.02–1.68]) and the apoB-to-apoAI ratio (per SD increase, 1.48 [1.13–1.95]) were positively associated with diabetic retinopathy. Results were similar for mild to moderate diabetic retinopathy and VTDR. Traditional lipid levels improved the area under the receiver operating curve by 1.8%, whereas apolipoproteins improved the area by 8.2%.

CONCLUSIONS
ApoAI and apoB and the apoB-to-apoAI ratio were significantly and independently associated with diabetic retinopathy and diabetic retinopathy severity and improved the ability to discriminate diabetic retinopathy by 8%. Serum apolipoprotein levels may therefore be stronger biomarkers of diabetic retinopathy than traditional lipid measures.
Higher Plasma Levels of Advanced Glycation End Products Are Associated With Incident Cardiovascular Disease and All-Cause Mortality in Type 1 Diabetes
Authors: Nin Johanna W. , Jorsal Anders , Ferreira Isabel , Schalkwijk Casper G. , Prins Martin H. , Parving Hans-Henrik , Tarnow Lise , Rossing Peter , Stehouwer Coen D. 
Published: January 2011

OBJECTIVE
To investigate the associations of plasma levels of advanced glycation end products (AGEs) with incident cardiovascular disease (CVD) and all-cause mortality in type 1 diabetes and the extent to which any such associations could be explained by endothelial and renal dysfunction, low-grade inflammation, and arterial stiffness.

RESEARCH DESIGN AND METHODS
We prospectively followed 169 individuals with diabetic nephropathy and 170 individuals with persistent normoalbuminuria who were free of CVD at study entry and in whom levels of Nε-(carboxymethyl)lysine, Nε-(carboxyethyl)lysine, pentosidine and other biomarkers were measured at baseline. The median follow-up duration was 12.3 (interquartile range 7.6–12.5) years.

RESULTS
During the course of follow-up, 82 individuals (24.2%) died; 85 (25.1%) suffered a fatal (n = 48) and/or nonfatal (n = 53) CVD event. The incidence of fatal and nonfatal CVD and of all-cause mortality increased with higher baseline levels of AGEs independently of traditional CVD risk factors: hazard ratio (HR) = 1.30 (95% CI = 1.03–1.66) and HR = 1.27 (1.00–1.62), respectively. These associations were not attenuated after further adjustments for markers of renal or endothelial dysfunction, low-grade inflammation, or arterial stiffness.

CONCLUSIONS
Higher levels of AGEs are associated with incident fatal and nonfatal CVD as well as all-cause mortality in individuals with type 1 diabetes, independently of other risk factors and of several potential AGEs-related pathophysiological mechanisms. Thus, AGEs may explain, in part, the increased cardiovascular disease and mortality attributable to type 1 diabetes and constitute a specific target for treatment in these patients.
HbA1c in Nondiabetic Dutch Infants Aged 8–12 Months
Authors: Jansen Hanneke , Huiting Haika G. , Scholtens Salome , Sauer Pieter J.J. , Stolk Ronald P. 
Published: January 2011

OBJECTIVE
An international committee of experts recommended using HbA1c for diagnostic testing for diabetes. Little is known about normal values of HbA1c in infants. The aim of this study is to describe the distribution of HbA1c in 8- to 12-month-old nondiabetic infants.

RESEARCH DESIGN AND METHODS
HbA1c was measured in 86 infants participating in the Groningen Expert Center for Kids with Obesity (GECKO)-Drenthe birth cohort study. Anthropometric measurements were performed at Well Baby Clinics. Data on parents and children were collected prospectively using questionnaires.

RESULTS
HbA1c was normally distributed with a mean (SD) HbA1c level of 5.38% (0.24), range 4.8–6.0% or 35.29 mmol/mol (2.65), range 29.1–42.1 mmol/mol. Age, sex, birth weight, duration of breastfeeding, anthropometric measurements, and maternal BMI were not associated with HbA1c.

CONCLUSIONS
We found a normal distribution of HbA1c with a relatively high mean HbA1c of 5.38%. No significant association between risk factors for type 2 diabetes and HbA1c levels was found.