Nihat Dilsiz

Protective effects of selenium, vitamin C and vitamin E against oxidative stress of cigarette smoke in rats

Cataractous lenses have been found to have an altered distribution of the intracellular ionic environment; the concentrations of potassium and magnesium being decreased and the concentrations of sodium and calcium increased. These changes arise as a result of changes to lens membrane characteristics causing an increase in lens membrane permeability.

Determination of calcium, sodium, potassium and magnesium concentrations in human senile cataractous lenses

Cataractous lenses have been found to have a distribution of the intracellular ionic environment, the concentrations of potassium and magnesium decreasing and the concentrations of sodium and calcium increasing relative to the cytosol of most cells. This arises as a result of changes to lens membrane characteristics causing an increase in lens membrane permeability. These changes have been found to be initiated as a result of normal ageing of the human lens. In this study, total Ca2+, K+, Na+ and Mg2+ contents have been determined in human normal and cataractous lenses using atomic absorption and flame emission spectroscopy. The normal human lens Ca2+ is between 0·15 and 0·5 μmol g‐1 fresh lens weight; in senile cataracts the value increased up to 9·31 μmol g‐1 ( p < 0·0001). The normal levels of Na+, Mg2+ and K+ are 20, 5·5 and 60 μmol g‐1 respectively; these changed to 136·10, 3·60 and 9·33 μmol g‐1, respectively in cataractous senile human lenses ( p < 0·002, p < 0·002 and p < 0·01). The remarkable differences in these elements may play some role in cataractogenesis. Copyright

The study of renin–angiotensin–aldosterone in experimental diabetes mellitus

It is generally accepted that hypertension and other vascular pathologies increase in diabetes mellitus (DM) patients as a result of the renin–angiotensin–aldosterone (RAA) system. In this study, changes in the renin‐angiotensin‐aldosterone (RAA) system level was determined in Streptozotocin (STZ)‐injected rats. A total of 46 female Wistar albino rats (180–220 g body weight) was utilized in these experiments. STZ was given intraperitoneally to induce diabetes in rats. Streptozotocin (60 mg kg−1 body weight) was dissolved in 0·1 m citrate–‐phosphate buffer (pH 4–5). The non‐diabetic rats were injected with sterilized buffer alone to act as a control group. Blood glucose levels were 398±8·2 mg dl−1, 488±11·75 mg dl−1 and 658±29·6 mg dl−1 at days 3, 12 and 30 respectively. The level of plasma renin activity (PRA) was measured as 7·69±1·07 ng ml−1 h−1; 1·82±0·22 ng ml−1 h−1 and 0·67±0·12 ng ml−1 h−1 at days 3, 12 and 30, respectively. These values showed that the PRA levels are decreased with increased time period. Serum angiotensin converting enzyme (ACE, E.C. 3.4.15.1) levels were increased at days 12 and 30 (p<0·05 and p<0·005), whereas serum aldosterone levels were increased at days 3 and 12 (p<0·05). The level of urea and creatinine increased at days 12 and 30 (p<0·05 and p<0·005, respectively) when compared to the control group. The data from these experiments indicate that the PRA level decreased whereas ACE activity level increased in diabetic rats compared with the control. Aldosterone levels increased at the first stage of the experiment, but then decreased by the end of the experiment as a result of changes in renin and ACE levels. Copyright

The Effects of Dietary Selenium and Vitamin E and their Combination on the Fatty Acids of Erythrocytes, Bone Marrow and Spleen Tissue Lipids of Lambs

The object was to determine the influence of dietary vitamin E, selenium and their combination on the fatty acid con‐tent of erythrocytes, bone marrow and spleen lipids of Akkaraman lambs. After supplementation for 15 days, the amount of all fatty acids was slightly higher (p < 0·05) in the vitamin E as compared to the control group, whereas the amount of longer fatty acids was significantly higher (p < 0·01, p < 0·001) in the selenium and combination groups. On the thirtieth day, the amount of all fatty acids was slightly high (p < 0·5) in all the supplemented groups in comparison with the control group. In the bone marrow lipids, the amount of longer fatty acids was decreased (p < 0·05, p < 0·01, p < 0·001) in the vitamin E and combination groups as compared to the control. Although the amount of some fatty acids was high (p < 0·05, p < 0·01) in the selenium group compared to the control, linoleic (18:2), linolenic (18:3) and the polyunsaturated fatty acids (PUFA) were lower (p < 0·05, p < 0·001). In the spleen lipids, the amount of longer fatty acids was slightly decreased (p < 0·05) in the vitamin E group as compared with the control; however the amount of longer fatty acids was significantly higher (p < 0·05, p < 0·01) in the selenium and combination groups in comparison to the control group. Thus dietary supplementation with selenium was more effective than dietary vitamin E supplementation in altering the fatty acid content of the erythrocyte, bone marrow and spleen lipids.

The effects of selenium, vitamin E and their combination on the composition of fatty acids and proteins in Saccharomyces cerevisiae

The aim of our studies was to test the effect and role of vitamin E and selenium supplements on yeast cell. In this study, the effects of selenium (Se), vitamin E (Vit. E), and their combination (Se plus Vit. E) on the composition of fatty acids and proteins were examined in Saccharomyces cerevisiae strains WET136 and 522. S. cerevisiae cells were grown up in YEPD medium supplemented with Se, Vit. E or their combination. It was found that the level of stearic acid was increased in all supplemented groups (p<0·05; p<0·001). The content of saturated and unsaturated fatty acids was decreased (p<0·05; p<0·01; p<0·001) in Vit. E and Vit. E plus Se supplemented S. cerevisiae. On the other hand, Se alone caused an increase (p<0·001) in the saturated fatty acids but a decrease (p<0·05; p<0·001) in the unsaturated fatty acids. Total proteins in S. cerevisiae were significantly increased (p<0·001) by Vit. E supplement. There was no significant change observed in S. cerevisiae supplemented with Se. These findings indicate that membrane composition of S. cerevisiae is affected by both Vit. E and Se supplements.

Influences of Intraperitoneally and Dietary Administered Vitamin E and Selenium on the Lipid Composition in Reproductive Organs of Male Animals

The aim of this work was to determine the protective effect of intraperitoneally and dietary administered vitamin E and selenium (Se) on the total lipid, cholesterol, and fatty acid composition in rat and lamb testes. The level of total lipid in rat testes was significantly decreased (p < 0.001) in the combination group as compared to the control group but slightly decreased in lamb testes (p < 0.05). In addition, the level of total lipid in lamb testes was significantly decreased (p < 0.001) by the Se alone. The content of total cholesterol in rats was higher in the Se group and its level in lamb testes was higher in the vitamin E groups than in the control group (p < 0.001). In rats testes, the amounts of palmitic, oleic, arachidonic acids, the total fatty acid, total unsaturated and total omega 6 acids were higher (p < 0.001) in the Se group. The proportions of palmitic and arachidonic acids were reduced in the vitamin E group and linoleic acid, total unsaturated, and total omega 6 fatty acids were high (p < 0.05) in the vitamin E and combination groups. In lamb testis tissues, the amounts of palmitic, arachidonic, total unsaturated and total omega 6 fatty acids were decreased in the vitamin E group in comparison to the control (p < 0.05). However, the amounts of arachidonic and total omega 6 fatty acids increased (p < 0.05) in the Se group. The proportions of arachidonic acid, total unsaturated fatty acid and total omega 6 fatty acids were high (p < 0.05) in the Se and combination groups. We concluded that the level of total lipid in testis tissues was reduced by dietary and intraperitoneally administered vitamin E and Se together. In contrast, it seems that the proportions of unsaturated and essential fatty acids in examined tissues are increased by vitamin E and Se.

Effects of Vitamin E on Serum Glucose Levels and Nephropathy in Streptozotocin-Diabetic Rats

We investigated the effect of vitamin E on serum glucose levels and renal changes in streptozotocin-diabetic rats. Animals were treated every other day with 50 mg/kg doses of vitamin E for a week before streptozotocin treatment. After the final streptozotocin treatment, animals were treated daily with 20 mg/kg vitamin E for three days. The mean serum glucose levels in control diabetic rats was 387±15.35 mg/dL at day 3 and 548±47.75 mg/dL at day 15, compared with vitamin E-treated rats 326±33.76 mg/dL at day 3 and 498±13.74 mg/dL at day 15 (p<0.005 and p<0.05 respectively). There was also a significant decrease (p<0.005) in blood urea almost to normal levels. In histopathological studies, increased basement membrane thickness, focal glomerulosclerosis, partial tubular necrosis and tubular dilatation with ‘capsular drops’ in Bowmans capsules were established in control diabetic rats at day 15. Such changes were less pronounced or absent in vitamin E-treated diabetic rats.