ABSTRACT
The effect of NaOH solution on the formation of nanoparticles has been the subject of ongoing debate in selenium-based material research. In this project, the robust correlation between the mechanistic growth of zinc selenide/graphene oxide (ZnSe/GO) composite and the concentration of NaOH are elucidated. The ZnSe/GO composite was synthesized via microwave-assisted hydrothermal method and the concentrations of NaOH are controlled at 2 M, 3 M, 4 M, 5 M and 6 M. The XRD spectra show that the crystal phases of the samples exhibited a 100% purity of ZnSe when the concentration of sodium hydroxide (NaOH) was set at 4 M. The further increase of NaOH concentration leads to the formation of impurities. This result reflects the essential role of hydroxyl ions in modifying the purity state of ZnSe/GO composite. The optical band gap energy of ZnSe/GO composite also decreased from 2.68 eV to 2.64 eV when the concentration of NaOH increased from 2 M to 4 M. Therefore, it can be concluded that the optimum concentration of NaOH used in synthesizing ZnSe/GO composite is 4 M. This project provides an alternative green method in the formation of a high purity ZnSe/GO composite.
ABSTRACT
BACKGROUND: Angiogenic factors such as vascular endothelial growth factor (VEGF), erythropoietin, and angiopoietin play important roles in the pathophysiology of diabetic retinopathy. Increased amounts of reactive oxygen species (ROS) are also known to associated with diabetic retinopathy and VEGF expression. This study evaluated the effect of a simvastatin on ROS generation and the changes in various angiogenic factors in the retinas of diabetic rats. METHODS: The rats were divided into normal, diabetes mellitus (DM), and simvastatin-treated groups (each group, n = 10). Diabetes was induced by intraperitoneal injection of streptozotocin into 20 Sprague-Dawley rats. After diabetic induction, simvastatin (5mg/kg) was administered orally to ten rats. The expression levels of VEGF, erythropoietin, angiopoietin 1 and 2, and NADPH oxidase were examined in rat retinas by RT-PCR and Western blot. Superoxide formation was examined by dihydroethidium (DHE) staining. RESULTS: DHE analysis revealed increased superoxide formation in the retinas of the diabetic group, which was decreased in the group treated with simvastatin. Western blot analysis showed that NADPH oxidase levels were decreased in the diabetic group and remained normal in the simvastatin-treated group. Simvastatin treatment blocked hyperglycemia-induced increases in VEGF, angiopoietin 2 and erythropoietin levels, as demonstrated by RT-PCR and Western blot analysis. CONCLUSIONS: Simvastatin treatment led to suppression of superoxide formation and decreased expression of VEGF, angiopoietin 2 and erythropoietin in diabetic rat retinas.
Subject(s)
Angiogenic Proteins/metabolism , Diabetes Mellitus, Experimental/drug therapy , Diabetic Retinopathy/drug therapy , Hydroxymethylglutaryl-CoA Reductase Inhibitors/pharmacology , Simvastatin/pharmacology , Administration, Oral , Angiogenic Proteins/genetics , Angiopoietin-1/genetics , Angiopoietin-1/metabolism , Animals , Blotting, Western , Diabetes Mellitus, Experimental/metabolism , Diabetic Retinopathy/metabolism , Electrophoresis, Polyacrylamide Gel , Erythropoietin/genetics , Erythropoietin/metabolism , Fluorescent Antibody Technique, Indirect , Hydroxymethylglutaryl-CoA Reductase Inhibitors/administration & dosage , Male , NADPH Oxidases/metabolism , RNA, Messenger/metabolism , Rats , Rats, Sprague-Dawley , Reactive Oxygen Species/metabolism , Reverse Transcriptase Polymerase Chain Reaction , STAT3 Transcription Factor/genetics , STAT3 Transcription Factor/metabolism , Simvastatin/administration & dosage , Vascular Endothelial Growth Factor A/genetics , Vascular Endothelial Growth Factor A/metabolismABSTRACT
PURPOSE: Angiogenic factors such as vascular endothelial growth factor (VEGF), erythropoietin, and angiopoietin play important roles in the development of diabetic retinopathy. However, the suppression of a single factor does not inhibit angiogenesis completely. This study simultaneously evaluated the expression of several angiogenic factors in the retinas of diabetes-induced rats and determined the effects of an angiotensin-converting enzyme inhibitor (enalapril) on the expression of angiogenic factors. METHODS: Diabetes was chemically induced by injecting 14 of 21 Sprague-Dawley rats with streptozotocin. After induction of diabetes, enalapril (10 mg/kg) was administered orally to seven rats. The rats were divided into normal, diabetes mellitus (DM), and enalapril-treated groups (each group, n = 7). The eyeballs were removed at 8 weeks after the induction of diabetes, and the retinal expression of VEGF, the signal transducer and activator of transcription (STAT)3/5, erythropoietin, and angiopoietin were examined using immunohistochemistry, RT-PCR, and Western blotting. RESULTS: RT-PCR revealed that the expression of VEGF, VEGF receptors, STAT3, erythropoietin, erythropoietin receptor, STAT5, angiopoietin 2, and Tie2 mRNA increased in the DM group, whereas angiopoietin 1 expression decreased. The enalapril-treated group showed no increase in mRNA expression of angiogenic factors. Immunohistochemical staining and Western blotting showed that the expression of VEGF, STAT3, and erythropoietin receptor proteins increased in the DM group but not in the enalapril-treated group. Erythropoietin and angiopoietin proteins were not detected by immunohistochemical staining or Western blotting. STAT5 protein expression was detected only in the DM group using immunohistochemical staining and Western blotting. The mRNA expression of the angiogenic factors VEGF, erythropoietin, and angiopoietin 2 increased in the DM group but not in the enalapril-treated group. In contrast, angiopoietin 1 mRNA expression decreased in the DM group. CONCLUSIONS: Enalapril treatment prevented increased angiogenic factor levels in the retinas of experimentally induced diabetic rats.
