| 1. |
- Ahrén, Bo
(författare)
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beta- and alpha-Cell Dysfunction in Subjects Developing Impaired Glucose Tolerance Outcome of a 12-Year Prospective Study in Postmenopausal Caucasian Women
- 2009
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Ingår i: Diabetes. - : American Diabetes Association. - 1939-327X .- 0012-1797. ; 58:3, s. 726-731
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE-This study assessed insulin and glucagon secretion in relation to insulin sensitivity in Caucasian women who develop impaired glucose tolerance (IGT) versus those who maintain normal glucose tolerance (NGT) over a 12-year period. RESEARCH DESIGN AND METHODS-At baseline and after 3, 8, and 12 years, glucose tolerance (75-g oral glucose tolerance test), insulin sensitivity (euglycemic-hyperinsulinemic clamp), and insulin and glucagon secretion (2- to 5-min responses to 5 g arginine i.v. at fasting, 14 and >25 mmol/l glucose) were determined in 53 healthy Caucasian women (aged 58 years at. baseline) who all had NGT at baseline. RESULTS-During the 12-year period, 26 subjects developed IGT, whereas the remaining 27 subjects maintained NGT throughout the 12-year period. Subjects developing IGT had lower insulin sensitivity than those maintaining NGT in the tests preceding diagnosis of IGT (P <= 0.05). When judged in relation to insulin sensitivity, P-cell glucose sensitivity and maximal insulin secretion were lower in those who later developed IGT than in those maintaining NGT at all tests (P : 0.05). Furthermore, subject's who developed IGT had defective suppression of glucagon secretion by glucose in the test preceding diagnosis of IGT when they still had NGT (P : 0.05). CONCLUSIONS-beta- and alpha-cell dysfunction are evident several years before diagnosis of IGT, and islet dysfunction is manifeste as impaired glucose sensitivity of the beta- and (x-cells and reduced maximal insulin secretion. Diabetes 58:726-731, 2009
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| 2. |
- da Silva Xavier, Gabriela, et al.
(författare)
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TCF7L2 regulates late events in insulin secretion from pancreatic islet beta-cells
- 2009
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 58:4, s. 894-905
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Polymorphisms in the human TCF7L2 gene are associated with reduced insulin secretion and an increased risk of type 2 diabetes. However, the mechanisms by which TCF7L2 affect insulin secretion are still unclear. We define the effects of TCF7L2 expression level on mature beta-cell function and suggest a potential mechanism for its actions. RESEARCH DESIGN AND METHODS: TCF7L2 expression in rodent islets and beta-cell lines was altered using RNAi or adenoviral transduction. Beta-cell gene profiles were measured by quantitative real-time PCR and the effects on intracellular signaling and exocytosis by live cell imaging, electron microscopy, and patch clamp electrophysiology. RESULTS: Reducing TCF7L2 expression levels by RNAi decreased glucose- but not KCl-induced insulin secretion. The glucose-induced increments in both ATP/ADP ratio and cytosolic free Ca2+ concentration ([Ca2+]i) were increased compared with controls. Overexpression of TCF7L2 exerted minor inhibitory effects on glucose-regulated changes in [Ca2+]i and insulin release. Gene expression profiling in TCF7L2-silenced cells revealed increased levels of mRNA encoding syntaxin 1A but decreased Munc18–1 and ZnT8 mRNA. Whereas the number of morphologically docked vesicles was unchanged by TCF7L2 suppression, secretory granule movement increased and capacitance changes decreased, indicative of defective vesicle fusion. CONCLUSION: TCF7L2 is involved in maintaining expression of beta-cell genes regulating secretory granule fusion. Defective insulin exocytosis may thus underlie increased diabetes incidence in carriers of the at-risk TCF7L2 alleles.
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| 3. |
- Grunnet, Louise G., et al.
(författare)
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Regulation and Function of FTO mRNA Expression in Human Skeletal Muscle and Subcutaneous Adipose Tissue
- 2009
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Ingår i: Diabetes. - : American Diabetes Association. - 1939-327X .- 0012-1797. ; 58:10, s. 2402-2408
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE-Common variants in FTO (the fat mass- and obesity-associated gene) associate with obesity and type 2 diabetes. The regulation and biological function of FTO mRNA expression in target tissue is unknown. We investigated the genetic and nongenetic regulation of FTO mRNA in skeletal muscle and adipose tissue and their influence on in vivo glucose and fat metabolism. RESEARCH DESIGN AND METHODS-The FTO rs9939609 polymorphism was genotyped in two twin cohorts: 1) 298 elderly twins aged 62-83 years with glucose tolerance ranging from normal to type 2 diabetes and 2) 196 young (25-32 years) and elderly (58-66 years) nondiabetic twins examined by a hyperinsulinemic-euglycemic clamp including indirect calorimetry. FTO mRNA expression was determined in subcutaneous adipose tissue (n = 226) and skeletal muscle biopsies (n = 158). RESULTS-Heritability of FTO expression in both tissues was low, and FTO expression was not influenced by FTO rs9939609 genotype. FTO mRNA expression in skeletal muscle was regulated by age and sex, whereas age and BMI were predictors of adipose tissue FTO mRNA expression. FTO mRNA expression in adipose tissue was associated with an atherogenic lipid profile. In skeletal muscle, FTO mRNA expression was negatively associated to fat and positively to glucose oxidation rates as well as positively correlated with expression of genes involved in oxidative phosphorylation including PGC1 alpha. CONCLUSIONS-The heritability of FTO expression in adipose tissue and skeletal muscle is low and not influenced by obesity-associated FTO genotype. The age-dependent decline in FTO expression is associated with peripheral defects of glucose and fat metabolism. Diabetes 58:2402-2408, 2009
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| 4. |
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| 5. |
- Hiukka, A, et al.
(författare)
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ApoCIII-Enriched LDL in Type 2 Diabetes Displays Altered Lipid Composition, Increased Susceptibility for Sphingomyelinase and Increased binding to Biglycan.
- 2009
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Ingår i: Diabetes. - : American Diabetes Association. - 1939-327X .- 0012-1797. ; 58:9, s. 2018-2026
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Tidskriftsartikel (refereegranskat)abstract
- Objective- Apolipoprotein CIII (apoCIII) is an independent risk factor for cardiovascular disease, but the molecular mechanisms involved are poorly understood. Here, we investigated potential proatherogenic properties of apoCIII-containing LDL from hypertriglyceridemic patients with type 2 diabetes. Research design and methods - LDL was isolated from controls and subjects with type 2 diabetes, and from apoB transgenic mice. LDL-biglycan binding was analyzed with a solid-phase assay using immunoplates coated with biglycan. Lipid composition was analyzed with mass spectrometry. Hydrolysis of LDL by sphingomyelinase was analyzed after labeling plasma LDL with [(3)H]sphingomyelin. ApoCIII isoforms were quantified after isoelectric focusing. Human aortic endothelial cells were incubated with desialylated apoCIII or with LDL enriched with specific apoCIII isoforms. Results- We showed that enriching LDL with apoCIII only induced a small increase in LDL-proteoglycan binding, and this effect was dependent on a functional Site A in apoB100. Our findings indicated that intrinsic characteristics of the diabetic LDL other than apoCIII per se are responsible for further increased proteoglycan binding of diabetic LDL with high endogenous apoCIII, and we showed alterations in the lipid composition of diabetic LDL with high apoCIII. We also demonstrated that high apoCIII increased susceptibility of LDL to hydrolysis and aggregation by SMase. In addition, we demonstrated that sialylation of apoCIII increased with increasing apoCIII content, and that sialylation of apoCIII was essential for its proinflammatory properties. Conclusions- We have demonstrated a number of features of apoCIII-containing LDL from hypertriglyceridemic patients with type 2 diabetes that could explain the proatherogenic role of apoCIII.
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| 6. |
- Jonsson, Anna, et al.
(författare)
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A variant in the KCNQ1 gene predicts future type 2 diabetes and mediates impaired insulin secretion.
- 2009
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Ingår i: Diabetes. - : American Diabetes Association. - 1939-327X .- 0012-1797. ; 58:10, s. 2409-2413
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Tidskriftsartikel (refereegranskat)abstract
- Objective- Two independent genome wide association studies for type 2 diabetes in Japanese have recently identified common variants in the KCNQ1 gene to be strongly associated with type 2 diabetes. Here we studied whether a common variant in KCNQ1 would influence BMI, insulin secretion and action and predict future type 2 diabetes in subjects from Sweden and Finland. Research design and methods- Risk of type 2 diabetes conferred by KCNQ1 rs2237895 was studied in 2,830 type 2 diabetes cases and 3,550 controls from Sweden (Malmö Case-Control) and prospectively in 16,061 individuals from the Malmö Preventive Project (MPP). Association between genotype and insulin secretion/action was assessed cross-sectionally in 3,298 non-diabetic subjects from the PPP-Botnia Study and longitudinally in 2,328 non-diabetic subjects from the Botnia Prospective Study (BPS). KCNQ1 expression (n=18) and glucose-stimulated insulin secretion (n=19) was measured in human islets from non-diabetic cadaver donors. Results. The C-allele of KCNQ1 rs2237895 was associated with increased risk of type 2 diabetes in both the case-control (OR 1.23 [1.12-1.34], p=5.6x10(-6)) and the prospective (OR 1.14 [1.06-1.22], p=4.8x10(-4)) studies. Furthermore, the C-allele was associated with decreased insulin secretion (CIR p=0.013; DI p=0.013) in the PPP-Botnia study and in the BPS at baseline (CIR p=3.6x10(-4); DI p=0.0058) and after follow-up (CIR p=0.0018; DI p=0.0030). C-allele carriers showed reduced glucose-stimulated insulin secretion in human islets (p=2.5x10(-6)). Conclusion. A common variant in the KCNQ1 gene is associated with increased risk of future type 2 diabetes in Scandinavians which partially can be explained by an effect on insulin secretion.
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| 7. |
- Kacerovsky-Bielesz, Gertrud, et al.
(författare)
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Short-Term Exercise Training Does Not Stimulate Skeletal Muscle ATP Synthesis in Relatives of Humans With Type 2 Diabetes
- 2009
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Ingår i: Diabetes. - : American Diabetes Association. - 1939-327X .- 0012-1797. ; 58:6, s. 1333-1341
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE-We tested the hypothesis that short-term exercise training improves hereditary insulin resistance by stimulating ATP synthesis and investigated associations With gene polymorphisms. RESEARCH DESIGN AND METHODS-We studied 24 nono-bese first-degree relatives of type 2 diabetic patients and 12 control subjects at rest, and 48 h after three bouts of exercise. In addition to measurements of oxygen uptake and insulin sensitivity (oral glucose tolerance test), ectopic lipids and mitochondrial ATP synthesis were assessed using H-1 and P-31 magnetic resonance spectroscopy, respectively. They were genotyped for polymorphisms in genes regulating mitochondrial function, PPARGC1A (rs8192678) and NDUFB6 (rs540467). RESULTS-Relatives had slightly lower (P = 0.012) insulin sensitivity than control subjects. In control subjects, ATP synthase flux rose by 18% (P = 0.0001), being 23% higher (P = 0.002) than that in relatives after exercise training. Relatives responding to exercise training with increased ATP synthesis (+19%, P = 0.009) showed improved insulin sensitivity (P = 0.009) compared with those whose insulin sensitivity did not improve. A polymorphism in the NDUFB6 gene from respiratory chain complex I related to ATP synthesis (P = 0.02) and insulin Sensitivity response to exercise training (P = 0.05). ATP synthase flux correlated with O-2 uptake and insulin sensitivity. CONCLUSIONS-The ability of short-term exercise to stimulate ATP production distinguished individuals with improved insulin sensitivity from those whose insulin sensitivity did not improve. lit addition, the NDUFB6 gene polymorphism appeared to modulate this adaptation. This finding suggests that genes involved in mitochondrial function contribute to the response of ATP synthesis to exercise training. Diabetes 58:1333-1341, 2009
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| 8. |
- Kelliny, Clara, et al.
(författare)
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Common genetic determinants of glucose homeostasis in healthy children : the European youth heart study
- 2009
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 58:12, s. 2939-2945
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE-The goal of this study was to investigate whether the effects of common genetic variants associated with fasting glucose in adults are detectable in healthy children. RESEARCH DESIGN AND METHODS-Single nucleotide polymorphisms in MTNR1B (rs10830963), G6PC2 (rs560887), and GCK (rs4607517) were genotyped in 2,025 healthy European children aged 9-11 and 14-16 years. Associations with fasting glucose, insulin, homeostasis model assessment (HOMA)-insulin resistance (IR) and HOMA-B were investigated along with those observed for type 2 diabetes variants available in this study (CDKN2A/B, IGF2BP2, CDKAL1, SLC30A8, HHEX-IDE, and Chr 11p12). RESULTS-Strongest associations were observed for G6PC2 and MTNR1B, with mean fasting glucose levels (95% Cl) being 0.084 (0.06-0.11) mmol/l, P = 7.9 x 10(-11) and 0.069 (0.04-0.09) mmol/l, p = 1.9 x 10(-7) higher per risk allele copy, respectively. A similar but weaker trend was observed for GCK (0.028 [-0.006 to 0.06] mmol/l, P = 0.11). All three variants were associated with lower P-cell function (HOMA-B P = 9.38 x 10(-5), 0.004, and 0.04, respectively). SLC30A8 (rs13266634) was the only type 2 diabetes variant associated with higher fasting glucose (0.033 mmol/l [0.01-0.06], P = 0.01). Calculating a genetic predisposition score adding the number of risk alleles of G6PC2, MTNR1B, GCK, and SLC30A8 showed that glucose levels were successively higher in children carrying a greater number of risk alleles (P = 7.1 x 10(-17)), with mean levels of 5.34 versus 4.91 mmol/l comparing children with seven alleles (0.6% of all children) to those with none (0.5%). No associations were found for fasting insulin or HOMA-IR with any of the variants. CONCLUSIONS-The effects of common polymorphisms influencing fasting glucose are apparent in healthy children, whereas the presence of multiple risk alleles amounts to a difference of >1 SD of fasting glucose. Diabetes 58:2939-2945, 2009
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| 9. |
- Kindblom, Jenny, 1971, et al.
(författare)
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BMI Changes during Childhood and Adolescence as Predictors of Amount Adult Subcutaneous and Visceral Adipose Tissue in Men - the GOOD Study.
- 2009
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Ingår i: Diabetes. - : American Diabetes Association. - 1939-327X .- 0012-1797. ; 58:4, s. 867-874
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Tidskriftsartikel (refereegranskat)abstract
- Objective. The amount of visceral adipose tissue is a risk factor for the metabolic syndrome. It is unclear how body mass index (BMI) changes during childhood and adolescence predict adult fat distribution. We hypothesized that there are critical periods during development for the prediction of adult subcutaneous and visceral fat mass by BMI changes during childhood and adolescence. Research Design and Methods. Detailed growth charts were retrieved for the men participating in the population-based Gothenburg Osteoporosis and Obesity Determinants (GOOD) study (n=612). Body composition was analysed using Dual X-Ray Absorptiometry and adipose tissue areas using abdominal computed tomography at 18-20 years of age. Results. The main finding in the present study was that subjects with increases in BMI Z-score of >1 SD during adolescence had, independent of prepubertal BMI, both larger subcutaneous (+138%; p<0.001) and visceral adipose tissue areas (+91%; p< 0.001) than subjects with unchanged BMI Z-score. In contrast, subjects with increases in BMI Z-score of >1 SD during late childhood had larger amount adult subcutaneous adipose tissue (+83%; p< 0.001) than subjects with unchanged BMI Z-score, but unaffected amount of visceral adipose tissue. BMI changes during adolescence predict both visceral and subcutaneous adipose tissue of the abdomen while BMI changes during late childhood predict only the subcutaneous adipose tissue. Conclusions. The amount of visceral adipose tissue in young adult men was associated with BMI changes specifically during adolescence, while the amount of subcutaneous adipose tissue was associated with BMI changes during both late childhood and adolescence.
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| 10. |
- Kos, K., et al.
(författare)
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Regulation of the fibrosis and angiogenesis promoter SPARC/osteonectin in human adipose tissue by weight change, leptin, insulin, and glucose : Regulation of SPARC in human adipose tissue
- 2009
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Ingår i: Diabetes. - : American Diabetes Association. - 1939-327X .- 0012-1797. ; 58:8, s. 1780-8
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Matricellular Secreted Protein, Acidic and Rich in Cysteine (SPARC), originally discovered in bone as osteonectin, is a mediator of collagen deposition and promotes fibrosis. Adipose tissue collagen has recently been found to be linked with metabolic dysregulation. Therefore, we tested the hypothesis that SPARC in human adipose tissue is influenced by glucose metabolism and adipokines. RESEARCH DESIGN AND METHODS: Serum and adipose tissue biopsies were obtained from morbidly obese nondiabetic subjects undergoing bariatric surgery and lean control subjects for analysis of metabolic markers, SPARC, and various cytokines (RT-PCR). Additionally, 24 obese subjects underwent a very-low-calorie diet of 1,883 kJ (450 kcal)/day for 16 weeks and serial subcutaneous-abdominal-adipose tissue (SCAT) biopsies (weight loss: 28 +/- 3.7 kg). Another six lean subjects underwent fast-food-based hyperalimentation for 4 weeks (weight gain: 7.2 +/- 1.6 kg). Finally, visceral adipose tissue explants were cultured with recombinant leptin, insulin, and glucose, and SPARC mRNA and protein expression determined by Western blot analyses. RESULTS: SPARC expression in human adipose tissue correlated with fat mass and was higher in SCAT. Weight loss induced by very-low-calorie diet lowered SPARC expression by 33% and increased by 30% in adipose tissue of subjects gaining weight after a fast-food diet. SPARC expression was correlated with leptin independent of fat mass and correlated with homeostasis model assessment-insulin resistance. In vitro experiments showed that leptin and insulin potently increased SPARC production dose dependently in visceral adipose tissue explants, while glucose decreased SPARC protein. CONCLUSIONS: Our data suggest that SPARC expression is predominant in subcutaneous fat and its expression and secretion in adipose tissue are influenced by fat mass, leptin, insulin, and glucose. The profibrotic effects of SPARC may contribute to metabolic dysregulation in obesity.
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