High glucose lowers insulin receptor substrate 2 expression and induces apoptosis in mouse islet cells in vitro / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the role of insulin receptor substrate 2 (IRS2) and Bax on mouse islet cell apoptosis in the presence of high glucose in vitro.</p><p><b>METHODS</b>The pancreatic islet cells were isolated from Kunming mice and divided into 6 groups (G1-G6 groups) for a 72-h culture in the media containing different concentrations of glucose (5.6, 7.8, 11.1, 16.7, 22.2, and 27.6 mmol/L, respectively). Insulin secretion by the cells was evaluated by radioimmunoassay, and the expressions of IRS2 and Bax were detected using immunocytochemistry and immunofluorescence assay, respectively. Hoechst33342 staining was employed to observe the cell apoptosis.</p><p><b>RESULTS</b>Exposure to 5.6-11.1 mmol/L glucose resulted in increased insulin secretion and progressive elevation of IRS2 and Bax expression, whereas the cell apoptosis underwent no obvious changes. In the presence of glucose above 16.7 mmol/L, the percentages of apoptotic islet cells increased with glucose concentration, but insulin secretion and IRS2 expression decreased; Bax expression significantly increased in the presence of high-concentration glucose.</p><p><b>CONCLUSION</b>Prolonged exposure of mouse islet cells to high glucose induces apoptosis and impairs insulin secretion of the cells. Decreased IRS2 expression and increased Bax expression may play an important role in the glucotoxicity in mouse islet cells.</p>

Role of cytomegalovirus infection in the pathogenesis of type 2 diabetes mellitus / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To further study the role of human cytomegalovirus (HCMV) infection in the pathogenesis of the type 2 diabetes mellitus.</p><p><b>METHODS</b>HCMV DNA levels in sera from 29 type 2 diabetic patients and 23 controls were measured by quantitative polymerase chain reaction (PCR), and comparative analyses was made between HCMV DNA and T cell subsets, blood glucose (BG), insulin (Ins) and C peptide (C-P).</p><p><b>RESULTS</b>The levels of HCMV DNA were (1.81+/-1.67) x 10(8) copies/ml for type 2 diabetic patients, a level significantly higher than that (5.50+/-4.30) x 10(7) copies/ml of controls. The percentage of CD8 for type 2 diabetic patients with positive HCMV DNA was 29.53%+/-2.00%, being much higher than that for controls (27.13%+/-4.12%), while the ratio of CD4/CD8 1.24+/-0.05 was significantly lower than that 1.41+/-0.10 of controls. Fasting C-P of type 2 diabetic patients with positive HCMV DNA was far lower than that of those with negative HCMV DNA, but the differences of BG and Ins between the two groups were not significant.</p><p><b>CONCLUSION</b>Active HCMV infection of type 2 diabetic patients may suppress cellular immunity and its influence on the pathogenesis of the type 2 diabetes mellitus should be further studied.</p>