Lessons from in vitro perifusion of pancreatic islets isolated from 80 human pancreases.

We report the average insulin response to acute glucose measured by in vitro perifusion of pancreatic islets isolated from 80 consecutive human organs. Different perifusion parameters were considered [basal release, stimulation index (SI), time to peak, incremental area under the curve Δ-AUCa)], and the correlation among them was determined. SI positively correlated with Δ-AUCa (p < 0.001, r = 0.80) while negatively with time to peak (p < 0.05, r = −0.23). We also evaluated several variables of the isolation procedure that might affect responsiveness to glucose by human islets. Sex and age of pancreas donors, cold ischemia time, duration of the digestion, collagenase concentration, and lot characteristics (collagenase, trypsin, clostripain, and proteases activity), and final islet yield were considered. Multivariate regression analysis showed only an independent association between SI and the concentration of collagenase (p = 0.01)

The GLP-1 receptor agonists exenatide and liraglutide activate Glucose transport by an AMPK-dependent mechanism

Additional file 2: Figure S2. Effects of EXE on Glut-4 in cultured L6 myotubes. Myotubes were stimulated with 100 nmol/l EXE for 20 min or 48 h. Panel A shows qPCR of Glut-4 mRNA. In panel B is a representative western blot for Glut-4 and β-Actin (loading control). In panel C is a representative western blot for Glut-4 and β-IR (loading control) in plasma membrane (PM) extracts (Glut-4 translocation). For A and C panels, data are shown as fold increase over control ± SD of three independent experiments (*p < 0.001, vs Ctrl)

Predictive models of insulin resistance derived from simple morphometric and biochemical indices related to obesity and the metabolic syndrome in baboons

<p>Abstract</p> <p>Background</p> <p>Non-human primates are valuable models for the study of insulin resistance and human obesity. In baboons, insulin sensitivity levels can be evaluated directly with the euglycemic clamp and is highly predicted by adiposity, metabolic markers of obesity and impaired glucose metabolism (i.e. percent body fat by DXA and HbA_1c). However, a simple method to screen and identify obese insulin resistant baboons for inclusion in interventional studies is not available.</p> <p>Methods</p> <p>We studied a population of twenty baboons with the euglycemic clamp technique to characterize a population of obese nondiabetic, insulin resistant baboons, and used a multivariate linear regression analysis (adjusted for gender) to test different predictive models of insulin sensitivity (insulin-stimulated glucose uptake = Rd) using abdominal circumference and fasting plasma insulin. Alternatively, we tested in a separate baboon population (n = 159), a simpler model based on body weight and fasting plasma glucose to predict the whole-body insulin sensitivity (Rd/SSPI) derived from the clamp.</p> <p>Results</p> <p>In the first model, abdominal circumference explained 59% of total insulin mediated glucose uptake (Rd). A second model, which included fasting plasma insulin (log transformed) and abdominal circumference, explained 64% of Rd. Finally, the model using body weight and fasting plasma glucose explained 51% of Rd/SSPI. Interestingly, we found that percent body fat was directly correlated with the adipocyte insulin resistance index (r = 0.755, p < 0.0001).</p> <p>Conclusion</p> <p>In baboons, simple morphometric measurements of adiposity/obesity, (i.e. abdominal circumference), plus baseline markers of glucose/lipid metabolism, (i.e. fasting plasma glucose and insulin) provide a feasible method to screen and identify overweight/obese insulin resistant baboons for inclusion in interventional studies aimed to study human obesity, insulin resistance and type 2 diabetes mellitus.</p

Autoantibodies against the glial glutamate transporter GLT1/EAAT2 in Type 1 diabetes mellitus-Clues to novel immunological and non-immunological therapies

: Islet cell surface autoantibodies were previously found in subjects with type 1 diabetes mellitus (T1DM), but their target antigens and pathogenic mechanisms remain elusive. The glutamate transporter solute carrier family 1, member 2 (GLT1/EAAT2) is expressed on the membrane of pancreatic β-cells and physiologically controls extracellular glutamate concentrations thus preventing glutamate-induced β-cell death. We hypothesized that GLT1 could be an immunological target in T1DM and that autoantibodies against GLT1 could be pathogenic. Immunoprecipitation and ELISA experiments showed that sera from T1DM subjects recognized GLT1 expressed in brain, pancreatic islets, and GLT1-transfected COS7-cell extracts. We validated these findings in two cohorts of T1DM patients by quantitative immunofluorescence assays. Analysis of the combined data sets indicated the presence of autoantibodies against GLT1 in 32 of the 87 (37%) T1DM subjects and in none of healthy controls (n&nbsp;=&nbsp;64) (p&nbsp;&lt;&nbsp;0.0001). Exposure of pancreatic βTC3 cells and human islets to purified IgGs from anti-GLT1 positive sera supplemented with complement resulted in plasma membrane ruffling, cell lysis and death. The cytotoxic effect was prevented when sera were depleted from IgGs. Furthermore, in the absence of complement, 6 out of 16 (37%) anti-GLT1 positive sera markedly reduced GLT1 transport activity in βTC3 cells by inducing GLT1 internalization, also resulting in β-cell death. In conclusion, we provide evidence that GLT1 is a novel T1DM autoantigen and that anti-GLT1 autoantibodies cause β-cell death through complement-dependent and independent mechanisms. GLT1 seems an attractive novel therapeutic target for the prevention of β-cell death in individuals with diabetes and prediabetes

Coordinated Defects in Hepatic Long Chain Fatty Acid Metabolism and Triglyceride Accumulation Contribute to Insulin Resistance in Non-Human Primates

Non-Alcoholic fatty liver disease (NAFLD) is characterized by accumulation of triglycerides (TG) in hepatocytes, which may also trigger cirrhosis. The mechanisms of NAFLD are not fully understood, but insulin resistance has been proposed as a key determinant

Lessons from in Vitro Perifusion of Pancreatic Islets Isolated from 80 Human Pancreases

We report the average insulin response to acute glucose measured by in vitro perifusion of pancreatic islets isolated from 80 consecutive human organs. Different perifusion parameters were considered [basal release, stimulation index (SI), time to peak, incremental area under the curve Δ-AUCa)], and the correlation among them was determined. SI positively correlated with Δ-AUCa (p < 0.001, r = 0.80) while negatively with time to peak (p < 0.05, r = −0.23). We also evaluated several variables of the isolation procedure that might affect responsiveness to glucose by human islets. Sex and age of pancreas donors, cold ischemia time, duration of the digestion, collagenase concentration, and lot characteristics (collagenase, trypsin, clostripain, and proteases activity), and final islet yield were considered. Multivariate regression analysis showed only an independent association between SI and the concentration of collagenase (p = 0.01)

Development of motion analysis protocols based on inertial sensors and fluoroscopy

none9noneP. Garofalo; S. Fantozzi; A. G. Cutti; L. Tersi; A. Ferrari; M. Raggi; R. Stagni; A. Cappello; A. DavalliP. Garofalo; S. Fantozzi; A. G. Cutti; L. Tersi; A. Ferrari; M. Raggi; R. Stagni; A. Cappello; A. Davall