Effects of High Methionine Diet on Oxidative Stress in Serum, Apo-B Containing Lipoproteins, Heart, and Aorta in Rabbits

This study investigated in rabbits whether a high methionine (HM) diet influences oxidative stress parameters in serum, apo-B containing lipoproteins (LDL+VLDL), heart, and aorta. Rabbits received a normal commercial chow supplemented with 2% L-methionine (w/w) for 6 mo (approximately 1 g/kg body wt/day). Serum homocysteine (HCys), malondialdehyde (MDA), diene conjugate (DC), and cholesterol levels were found to be increased, but protein carbonyl (PC) and triglyceride levels remained unchanged in the HM group as compared to controls. Cholesterol, endogenous DC, and copper-induced MDA levels were significantly higher in the LDL+VLDL fraction of plasma lipoproteins in the HM group. MDA and DC levels were found to be increased in homogenates of heart and aorta in the HM group. The HM diet caused significant increases in cardiac glutathione peroxidase activity, but glutathione, vitamin E, and vitamin C levels and superoxide dismutase and glutathione transferase activities remained unchanged. There were no significant differences in the cholesterol levels and histopathological findings in the aortas of the control vs the HM group. This study demonstrates that a HM diet induces oxidative stress in serum, apo-B containing lipoproteins, heart, and aorta in rabbits

Collagen Synthesis, Nitric Oxide and Asymmetric Dimethylarginine in Diabetic Subjects Undergoing Hyperbaric Oxygen Therapy

The main pathological condition in patients with impaired wound healing is diabetes mellitus. These patients have significantly low circulating nitric oxide (NO) levels because the stimulatory action of insulin on NO synthesis is absent. Additionally, asymmetric dimethylarginine (ADMA), an inhibitor of NO synthase, is increased owing to the generation of oxidative stress. NO was thought to contribute to wound healing. Hyperbaric oxygen (HBO) treatment is generally used in order to accelerate the healing of wounds. The aim of this study was to determine the changes in plasma procollagen type I and III N-terminal peptides (PINP and PIIINP), total nitrite/nitrate (NOx) and ADMA levels; and to evaluate their relation to healing during the HBO treatment of foot ulcers. Data obtained from 18 diabetic patients before and after the HBO therapy were compared statistically by the Wilcoxon test. NOx was increased in 11 and ADMA was decreased in 12 patients following HBO treatment. Both PINP (32.6+/-29.4 mu g/l vs 44.3+/-33.4 mu g/l) and PIIINP (6.97+/-3.01 mu g/l vs 7.92+/-2.49 mu g/l) were significantly increased (p<0.05). Progressive reductions were observed in wound areas, as assessed by the digital wound imaging. In 12 patients, wounds healed by 50 % or higher; whereas only two subjects had minimal improvements (15 % or less healing). The duration of diabetes correlated negatively with wound healing (r = -498, p<0.05). This study suggests that increased collagen synthesis is associated with wound healing during hyperbaric oxygen therapy. Nitric oxide generation may also contribute to the healing process