Funda Kiral

Effects of xylene and formaldehyde inhalations on renal oxidative stress and some serum biochemical parameters in rats.

In this study, it was aimed to demonstrate the possible renal oxidative stress and some serum biochemical parameters and their alterations caused by the exposure to xylene and formaldehyde (HCHO) in rats. Weighing 150—200 g, 12-week-old, 24 female Sprague-Dawley rats were used. The rats were randomly divided into four groups: Group 1 (control), Group 2 (300-ppm technical xylene), Group 3 (6-ppm HCHO) and Group 4 (150-ppm technical xylene + 3-ppm HCHO). The animals were exposed to gases eight hours per day for six weeks. Superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activities, glutathione (GSH) and malondialdehyde (MDA) levels were measured. In addition, serum total protein, albumin, urea and creatinine levels were evaluated. Compared with the control animals, urea levels increased significantly in all groups (P < 0.001). GSH activities and MDA levels increased in xylene and xylene + HCHO groups (P < 0.05). No statistically considerable differences were found in SOD, CAT and GSH-Px activities, total protein, albumin and creatinine levels among all groups (P > 0.05). The present study indicates but not statistically confirms the renal toxicity of the exposures to xylene, HCHO and a mixture of them.

The protective effects of vitamin C on the DNA damage, antioxidant defenses and aorta histopathology in chronic hyperhomocysteinemia induced rats

The aim of this study was to investigate the protective effect of vitamin C towards hyperhomocysteinemia (hHcy) induced oxidative DNA damage using the comet assay. The increase in plasma homocysteine levels is an important risk factor for vascular and cardiovascular diseases through free radical production. This study was also conducted to investigate the histopathological changes in the thoracic aorta and the oxidant/antioxidant status in heart, liver and kidney tissues. Twenty-four adult male Wistar rats were divided as control, hHcy and hHcy+vitamin C group. Chronic hHcy was induced by oral administration of l-methionine (1g/kg/day) for 28 days. Vitamin C was given 150mg/kg/day within the specified days. DNA damage was measured by use of the comet assay in lymphocytes. Levels of malondialdehyde (MDA) and glutathione (GSH) as well as catalase (CAT) and superoxide dismutase (SOD) activities were determined in heart, liver and renal tissues. Results show that l-methionine administration significantly increased % Tail DNA and Mean Tail Moment in hHcy group as compared with other groups. Vitamin C treatment significantly decreased the high MDA levels and increased activity of antioxidant enzymes in tissues. Aortic diameter and thickness of aortic elastic laminae were significantly lower in hHcy+vitamin C group. Comet assay can be used for the assessment of primary DNA damage caused by hHcy. Histopathological findings showed that vitamin C may have a preventive effect in alleviating the negative effects of hHcy. Vitamin C might be useful in the prevention of endothelial dysfunction caused by hHcy.

Measurement of asymmetric dimethylarginine, nitric oxide levels and total antioxidant capacity in experimcntal diabetic rats

Diabetes is one of the systemic chronic metabolic diseases accompanied by hyperglycemia, dyslipidemia, glycosuria and much clinical and biochemical evidence (18). In diabetes, both acute and chronic complications can be seen in all organs. This is suggested to be caused by the tissue damage formed with autoxidation of glucose, protein glycation and auto-oxidative glycation with free radicals (23). In studies showing the relationship between reactive oxygen species and diabetes and complications of diabetes, it has been emphasized that the tissue damage induced by non-enzymatic glycation, metabolic stress caused by changes in energy metabolism, hypoxia and ischemia-reperfusion increases free radical production and alters the antioxidant defense system (9). Asymmetric dimethylarginine (ADMA) is a proteolytic by-product of arginine methylation found in the plasma, urine and tissues. ADMA is guanidino analogue of L-arginine and synthesized endogenously and metabolised by dimethylarginine dimethylaminohydrolases (DDAHs). In the protection of vascular tone and its structure, vasoactive mediators released from endothelial play an important role and nitric oxide (NO) is one of the most important of these mediators. Nitric oxide plays an important role in the regulation of vascular tone and platelet adhesion and aggregation. On the other hand, arginine and ADMA-DDAK pathway play an important role in the regulation of nitric oxide synthesis. ADMA is determined to be inhibiting the NOS enzyme (29). Lipids are biomolecules that are most vulnerable to the effects of free radicals. Unsaturated bonds of cholesterol and fatty acids of cell membranes create peroxidation products by easily entering reaction with free radicals (6). Under normal conditions, organisms have an antioxidant defense system struggling with free radicals caused by endogenous or exogenous reasons and Measurement of asymmetric dimethylarginine, nitric oxide levels and total antioxidant capacity in experimental diabetic rats