Yazar "Ozturk, Guler" seçeneğine göre listele
Listeleniyor 1 - 8 / 8
Sayfa Başına Sonuç
Sıralama seçenekleri
Yayın Age-related changes in the rat brain mitochondrial antioxidative enzyme ratios: Modulation by melatonin(PERGAMON-ELSEVIER SCIENCE LTD, 2012) Ozturk, Guler; Akbulut, K. Gonca; Guney, Sevin; Acuna-Castroviejo, DarioOxidative stress is an important factor for aging. The antioxidative enzymes glutathione peroxidase (GPx), glutathione reductase (GRd) and superoxide dismutase (SOD) play a crucial role protecting the organism against the age-dependent oxidative stress. Glutathione (GSH) is present in nearly all living cells. GSH is one of the main antioxidants in the cell and it serves several physiological functions. Our purpose was to evaluate the age-related changes in mitochondrial GPx, GRd and SOD activities, and mitochondrial GSH pool in the brains of young (3 months) and aged rats (24 months). We also investigated whether melatonin administration influences these brain mitochondrial enzyme activities and GSH levels in young and aged rats. The results showed that GPx activity increased with age, whereas melatonin treatment decreased GPx activity in the aged rats at levels similar to those in young and young + melatonin groups. The activities of GRd and SOD, however, did not change with age. But, melatonin treatment increased SOD activity in the aged rats. GSH levels, which also increased with age, were not modified by melatonin treatment. The reduction in the SOD/GPx and GR/GPx ratios with age was prevented by melatonin administration. Together, our results suggest that the age-related oxidative stress in rat brain mitochondria is more apparent when the antioxidant enzyme ratios are analyzed instead of their absolute values. The antioxidative effects of melatonin were also supported by the recovery of the enzyme ratios during aging. (C) 2012 Elsevier Inc. All rights reserved.Yayın Comparison of Melatonin and Ozone in the Prevention of Reperfusion Injury Following Unilateral Testicular Torsion in Rats(ELSEVIER SCIENCE INC, 2012) Ekici, Sinan; Ekici, A. Isin Dogan; Ozturk, Guler; Aksungar, Fehime Benli; Sinanoglu, Orhun; Turan, Guven; Luleci, NurettinOBJECTIVE To compare the efficacy of ozone with melatonin, shown as the most powerful antioxidant in attenuation of testicular ischemia/reperfusion injury, in an experimental rat model of testicular torsion/detorsion. METHODS Twenty-four male Wistar rats were divided into 4 groups: sham-operated, torsion/detorsion, torsion/detorsion plus melatonin, and torsion/detorsion plus ozone. Melatonin (10 mg/kg) and ozone (4 mg/kg) were intraperitoneally injected daily beginning 15 minutes before detorsion for the following 7 days. At the seventh day, blood and tissue samples were obtained. Johnsen score, malondialdehyde, inhibin B, glutathione plasma total sulfhydryl group (RSH) levels, and total nitric oxide were studied. RESULTS Torsion/detorsion caused increase in tissue malondialdehyde and total nitric oxide along with a decrease in Johnsen score, tissue and plasma inhibin B, RSH, and glutathione levels. Melatonin prevented the rise in malondialdehyde and total nitric oxide levels and improved Johnsen score, tissue and plasma inhibin B, and tissue glutathione levels, along with a decrease in plasma RSH level. Ozone showed similar results except for the total nitric oxide level. Concomitantly, in contralateral testis, melatonin and ozone induced similar changes for Johnsen score, malondialdehyde, and inhibin B (not significant) and in glutathione (significant). Melatonin decreased the total nitric oxide level in both testes and ozone increased the same parameter. CONCLUSION On different pathways, ozone was comparable with melatonin in the amelioration of ischemia/reperfusion injury. Protective effects of ozone were associated with nitrous oxide. The potential for ozone as a treatment for torsion/detorsion therefore deserves to be further elucidated. UROLOGY 80: 899-906, 2012. (C) 2012 Elsevier Inc.Yayın Comparison of Melatonin Effect on Oxidant Status and Antioxidant Capacity in Liver and Heart of Young and Aged Rats(ELSEVIER TAIWAN, 2013) Guney, Sevin; Cumaoglu, Ahmet; Ozturk, Guler; Akbulut, K. Gonca; Karasu, CimenBackground: Oxidative stress is involved in several pathologic conditions such as metabolic or cardiovascular disease, and in aging. Oxidative damage of biomolecules increases with age. Melatonin is the main neurohormone of the pineal gland and specific antioxidants may act against age-related oxidative damage. Objective: This study investigated the effects of administration of melatonin on aging-related parameters such as total oxidant status (TOS), hydrogen peroxide (H2O2) and lipid hydroperoxide (LOOH) levels and total antioxidant capacity (TAC) in the heart and liver in a rat model of aging. Methods: Young (3-month-old) and aged (24-month-old) male Wistar rats were divided into control and melatonin-treated groups. Melatonin was given for 21 days (10 mg/kg/day). At the end of the treatment period, TOS, TAC, H2O2, and LOOH levels were measured. Results: H2O2 in the liver, but not in the heart, was found to be increased in aged rats. Melatonin treatment diminished H2O2 in the heart of both group of rats compared with those of untreated control rats. Melatonin treatment also led to a decrease in H2O2 in the liver of aged rats. LOOH were found to be increased in both tissues of aged rats whereas melatonin treatment decreased LOOH levels in heart and liver tissues of aged rats. In the young rats melatonin also inhibited LOOH in liver. TAC in heart and liver was not found to be statistically different between young and aged rats. In young rats, melatonin treatment resulted in an increase in TAC that was associated with increased H2O2. In the liver and heart of the rats, TOS was increased with age and was ameliorated by melatonin treatment. Conclusion: Our results demonstrate that there is no dramatic overall decline in the antioxidant system with age. However, total oxidant status increased with age. Melatonin has a restorative effect on oxidative status. Copyright (C) 2012, Taiwan Society of Geriatric Emergency & Critical Care Medicine. Published by Elsevier Taiwan LLC. All rights reserved.Yayın Exercise and melatonin in humans: reciprocal benefits(WILEY-BLACKWELL, 2012) Escames, Germaine; Ozturk, Guler; Bano-Otalora, Beatriz; Pozo, Maria J.; Madrid, Juan A.; Reiter, Russel J.; Serrano, Eric; Concepcion, Melquiades; Acuna-Castroviejo, DarioThe aim of this review is to update the reader as to the association between physical exercise and melatonin, and to clarify how the melatonin rhythm may be affected by different types of exercise. Exercise may act as a zeitgeber, although the effects of exercise on the human circadian system are only now being explored. Depending on the time of the day, on the intensity of light, and on the proximity of the exercise to the onset or decline of the circadian production of melatonin, the consequence of exercise on the melatonin rhythm varies. Moreover, especially strenuous exercise per se induces an increased oxidative stress that in turn may affect melatonin levels in the peripheral circulation because indole is rapidly used to combat free radical damage. On the other hand, melatonin also may influence physical performance, and thus, there are mutually interactions between exercise and melatonin production which may be beneficial.Yayın Histochemical observations on protective effects of melatonin against carbon tetrachloride (CCl4) - induced hepatotoxicity(WILEY-BLACKWELL, 2015) Ozerkan, Dilsad; Ozsoy, Nesrin; Akbulut, K. Gonca; Guney, Sevin; Ozturk, Guler…Yayın Melatonin with 1,25-Dihydroxyvitamin D3 Protects against Apoptotic Ischemia-Reperfusion Injury in the Rat Kidney(INFORMA HEALTHCARE, 2012) Sinanoglu, Orhun; Sezgin, Gulbuz; Ozturk, Guler; Tuncdemir, Matem; Guney, Sevin; Aksungar, Fehime Benli; Yener, NeseThis study was designed to evaluate the preventive role of melatonin (Mel) and 1,25-dihydroxyvitamin D3 (VD3) in biochemical and apoptotic events leading to tissue injury and renal dysfunction after ischemia-reperfusion (I/R). Thirty male Wistar rats were divided into five groups: sham-operated, I/R, Mel + I/R, VD3 + I/R, and Mel + VD3 + I/R. The rats were intraperitoneally administered with Mel (10 mg/kg), VD3 (0.5 mu g/kg), or Mel (10 mg/kg) plus VD3 (0.5 mu g/kg) each day at 1 week prior to ischemia. Right nephrectomy was initially performed and left renal I/R injury was induced by 45 min of bilateral renal ischemia followed by 45 min of reperfusion. After reperfusion, kidneys and blood were obtained for histopathologic and biochemical evaluation. Mel and VD3 had an ameliorative effect on biochemical parameters such as serum creatinine, blood urea nitrogen, alanine aminotransferase, aspartate aminotransferase, and apoptosis (caspase-3 and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling staining) in the kidneys against renal I/R injury in rats. Additionally, VD3 combined with Mel significantly reduced apoptotic and histological alterations when compared with Mel or VD3 alone. This preventive effect on renal tubular apoptosis was remarkable when Mel was combined with VD3.Yayın Protective Effect of Melatonin and 1,25-Dihydroxyvitamin D3 on Renal Ischemia-Reperfusion Injury in Rats(INFORMA HEALTHCARE, 2013) Sezgin, Gulbuz; Ozturk, Guler; Guney, Sevin; Sinanoglu, Orhun; Tuncdemir, MatemIschemia-reperfusion (I/R) injury induces the generation of reactive oxygen species (ROS) which affect many organs. This study was designed to investigate the roles of melatonin and 1,25-dihydroxyvitamin D-3 (VD3) on renal I/R injury. Thirty male Wistar albino rats were divided into five groups: group 1, control; group 2, right nephrectomy (RN) + I/R in the contralateral kidney; group 3, melatonin + RN + I/R; group 4, VD3 + RN + I/R; and group 5, melatonin + VD3 + RN + I/R. Melatonin (10 mg/kg), VD3 (0.5 mu g/kg), and melatonin plus VD3 were injected intraperitoneally for 7 days before renal I/R. After 7 days, right nephrectomy was initially performed and left renal artery was clamped for 45 min. After 45-min reperfusion, the serum and kidney tissue samples were obtained for assays. Melatonin and VD3 had an ameliorative effect on biochemical parameters such as serum creatinine (SCr) and blood urea nitrogen (BUN). Renal tissue malondialdehyde (MDA), glutathione (GSH), nitric oxide (NO) levels, and superoxide dismutase (SOD) activity were determined. Renal I/R decreased the kidney tissue GSH levels and SOD activity and increased the NO levels as compared with control group. However, melatonin and VD3 and melatonin plus VD3 treatment significantly increased the tissue GSH levels and SOD activity and decreased the NO levels compared with those of I/R group. Meanwhile, MDA levels were not different between the control and I/R groups. But, MDA levels decreased in all treated groups compared to I/R and control groups. These data support that melatonin and VD3 have beneficial effects on renal injury.Yayın VITAMIN D LEVELS OF OUTPATIENTS ADMITTED TO A UNIVERSITY HOSPITAL IN THE MARMARA REGION OF TURKEY OVER 3 YEARS(DE GRUYTER POLAND SP ZOO, 2019) Sezgin, Gulbuz; Ozturk, Guler; Turkal, Rana; Caykara, BurcuBackground: Vitamin D regulates calcium and phosphorus metabolism, and it is essential for bone formation. Several factors can affect vitamin D levels in plasma. In present study we compare vitamin D levels of outpatients, who admit to Maltepe University Hospital between 2011 and 2013 and had vitamin D measurements regarding gender, age, and season. Methods: Hospital records were evaluated to identify the outpatients with vitamin D levels and their gender, age, and vitamin D levels and the seasons of measurements were recorded. Results: Data of 4860 subjects (74% female) were analyzed and 69.2% were between 18-64 years old. Vitamin D levels were as follows: 43.1% <= 10 ng/mL, 31.9% between 10 ng/mL and 20 ng/mL, 16.1% between 20 ng/mL and 30 ng/mL, and only 8.9% >= 30 ng/mL. The number of females with vitamin D levels < 10 ng/mL was significantly higher than that of males, while the number of males with vitamin D levels between 10 ng/mL and 20 ng/mL was significantly higher than that of females (P = 0.001) for each of the individuals, 6.2% and 11.1% had sufficient levels in winter and summer, respectively. Overall, it was observed that 6.6% of individuals between 18-44 years old, 8.2% of individuals between 45-64 years old and 10.3% of individuals over 65 years old had vitamin D levels > 30 ng/mL. Conclusions: The prevalence of vitamin D deficiency in outpatients of Maltepe University Hospital in Marmara region was 75% (< 20 ng/mL).
