ABSTRACT
OBJECTIVE: To investigate the roles of DNA double stains damage repairing mechanisms in high glucose-induced cellular senescence. METHODS: Human umbilical vein endothelial cells (HUVECs) were incubated with different concentrations of glucose (5.5 mmol/L, 11 mmol/L, 22 mmol/L and 33 mmol/L) for 72 hrs before the assay of senescence-associated beta-galactosidase staining. The superoxides were detected by flow cytometry. The levels of NO were detected by enzyme assay. Gamma-H2AX and phosphorylated P53 protein were measured by Western blot. Changes after co-incubation with KU55993 (an inhibitor of ATM) were examined with methods mentioned above. RESULTS: Compared with control group, percentage of positive cells of senescence-associated beta-galactosidase staining increased significantly in high glucose groups. The corresponding levels of reactive oxygen increased and NO decreased in a concentration-dependent manner. Intra-cellular levels of gamma-H2AX and phosphorylated P53 protein were significantly increased in high glucose groups. Statistical significances were revealed between high-glucose group and control group, as well as among different high-glucose groups, but no significant difference was observed between mannitol and control group. KU55993, an inhibitor of ATM, significantly reduced the levels of gamma-H2AX, phosphorylated P53 protein, and positive rate of senescence-associated beta-galactosidase staining. CONCLUSION: High glucose may promote DNA double strains damage by enhancing oxidative stress and decreasing NO, and thus accelerate cellular senescence. ATM-P53 pathway, the key proteins related to DNA double strain damage repairing mechanisms, may play an important role in high glucose induced cellular senescence and atherosclerosis.
Subject(s)
Cellular Senescence/drug effects , DNA Damage/drug effects , Glucose/pharmacology , Human Umbilical Vein Endothelial Cells/pathology , Cells, Cultured , DNA Breaks, Double-Stranded/drug effects , Histones/metabolism , Human Umbilical Vein Endothelial Cells/metabolism , Humans , Morpholines , Nitric Oxide/analysis , Pyrones , Tumor Suppressor Protein p53/metabolism , beta-Galactosidase/metabolismABSTRACT
OBJECTIVE: To conduct a meta-analysis on the effects of testosterone on the related factors of metabolic syndrome in hypogonadal males. METHODS: Based on the principles and methods of Cochrane systematic reviews, we searched the PubMed (1980 to August 2009), Embase (1980 to August 2009), the Cochrane Central Register of Controlled Trials and CNKI (1995 to August 2009) , and handsearched some relevant journals and conference proceedings as well. We also identified randomized controlled trials addressing the use of testosterone for the treatment of hypogonadism, screened the retrieved studies according to the predefined inclusion and exclusion criteria, evaluated the quality of the included studies, and performed a meta-analysis on the results of homogeneous studies using the Cochrane Collaboration's RevMan 5.0 software. RESULTS: Six randomized controlled trials were included. The results of analysis indicated that testosterone substitution could significantly ameliorate fasting blood glucose, total cholesterol and insulin resistance in hypogonadism patients, and it could also reduce LDL, HDL, triglyceride and systolic blood pressure, though with no significant difference from the controls. However, there was insufficient evidence to show the effects of testosterone on waist circumference, waist-hip ratio and diastolic blood pressure. CONCLUSION: Existing clinical evidence has demonstrated the positive effects of testosterone substitution on the improvement of insulin resistance, blood glucose and lipids, but due to the heterogeneity and high risk of bias in the included studies, the evidence might be insufficient to give full support to the demonstration. Further large-scale trials are required to define the metabolic effects of testosterone in the treatment of hypogonadism.
