Hyperglycaemia enhances nitric oxide production in diabetes: a study from South Indian patients.

BACKGROUND: We have previously reported that increased glucose levels were associated with higher serum nitric oxide (NO) levels in fructose-fed insulin resistant rats. However, the relationship between hyperglycemia and serum NO level was not clear. Therefore, the present study was designed to find the association between hyperglycemia and serum NO levels in Type 2 diabetic (T2DM) patients and T2DM with cardiovascular complication. METHODS: Endothelial cells (HUVEC) were treated with of D-glucose (10-100mM), and NO levels and NOS gene expression was measured. Hyperglycaemia was induced in Sprague-Dawley rats, and serum NO levels were measured after 8 weeks. For clinical evaluation, five groups of patients were recruited: Control (CT, n=48), Type 2 diabetes (T2DM, n=26), T2DM with hypertension (DMHT, n=46), Coronary artery diseases (CAD, n=29) and T2DM with coronary artery diseases (DMCD, n=38). NO (nitrite + nitrate) levels were measured from human serum. RESULTS: We found a significant (p<0.05) and dose-dependent increase in NO levels in HUVEC cells after 4 hours of high glucose exposure. eNOS and iNOS gene expression was increased in HUVEC cells after different concentrations and time periods of glucose treatment. We also observed significant (149.1 ± 25 µM, p<0.01) increase in serum NO levels in hyperglycaemic rats compared to control (76.6 ± 13.2 µM). Serum NO level was significantly higher in T2DM (111.8 µM (81.7-122.4), p<0.001) and DMCD patients ((129.4 µM (121.2-143.5), p <0.001) but not in CAD patients (76.4 µM (70.5-87)), as compared to control (68.2 µM (56.4-82.3)). We found significantly lower NO levels (83.5 µM (60.5-122.9)) in subjects suffering from diabetes since more than 5 years, compared to subjects (115.3 µM (75.2-127.1), p<0.001) with less than 5 years. CONCLUSION: In conclusion, high NO levels were observed in South Indian diabetic patients. Higher glucose levels in serum might be responsible for activation of endothelial cells to enhance NO levels.

The induction of angiogenesis by cerium oxide nanoparticles through the modulation of oxygen in intracellular environments.

Angiogenesis is the formation of new blood vessels from existing blood vessels and is critical for many physiological and pathophysiological processes. In this study we have shown the unique property of cerium oxide nanoparticles (CNPs) to induce angiogenesis, observed using both in vitro and in vivo model systems. In particular, CNPs trigger angiogenesis by modulating the intracellular oxygen environment and stabilizing hypoxia inducing factor 1α endogenously. Furthermore, correlations between angiogenesis induction and CNPs physicochemical properties including: surface Ce(3+)/Ce(4+) ratio, surface charge, size, and shape were also explored. High surface area and increased Ce(3+)/Ce(4+) ratio make CNPs more catalytically active towards regulating intracellular oxygen, which in turn led to more robust induction of angiogenesis. Atomistic simulation was also used, in partnership with in vitro and in vivo experimentation, to reveal that the surface reactivity of CNPs and facile oxygen transport promotes pro-angiogenesis.