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Öğe The effect of the sulfonylurea glyburide on glutathione-S-transferase and glucose-6-phosphate dehydrogenase in streptozotocin-induced diabetic rat liver(Springer-Verlag Italia Srl, 2006) Buğdaycı, Güler; Altan, Nilgün; Sancak, Banu; Bukan, Neslihan; Kosova, FundaFree radical-induced lipid peroxidation has been associated with numerous disease processes including diabetes mellitus. Glutathione-S-transferase (GST) catalyses the conjugation of glutathione with a variety of organic peroxides to form more water-soluble compounds. Glucose-6-phosphate dehydrogenase (G6PDH) is essential to control intracellular reductive potential by increasing glutathione intracellular levels, which in turn decrease the amount of reactive oxygen species. Glyburide decreases glucose production and enhances insulin action in liver. The aim of this study was to examine the effects of glyburide on the antioxidant enzyme activities in the liver tissue of diabetic rat. We investigated the activities of GST and G6PDH in the liver of both control and streptozotocin-induced diabetic rats. Forty male albino rats were included in this study. Liver GST and G6PDH activities decreased significantly in five-week diabetic rats (p < 0.001 and p < 0.001 respectively) compared to controls and glyburide therapy restored these activities (p < 0.001 for GST and p < 0.001 for G6PDH). Elevations of hepatic antioxidant enzymes with glyburide administration suggest that glyburide may directly alter hepatic enzyme activities.Öğe Effects of melatonin on streptozotocin-induced diabetic liver injury in rats(Elsevier Gmbh, Urban & Fischer Verlag, 2006) Güven, Aysel; Yavuz, Özlem; Çam, Meryem; Ercan, Feriha; Bukan, Neslihan; Çomunoğlu, Cem; Gökçe, FatihThis study investigated the possible protective effects of melatonin as an antioxidant against streptozotocin (STZ)-induced diabetic liver injury in rats. Wistar rats were divided into four groups: untreated control (UC), melatonin-treated control (MC), untreated diabetic (UD), and melatonin-treated diabetic (MD). Experimental diabetes was induced by a single-dose (60 mg/kg, intraperitoneally (ip)) STZ injection, and metatonin was injected (200 wg/kg/day, ip) for 4 weeks. Upon light and electron microscopic examination, we observed that metatonin improved the morphological and histopathological changes of the liver caused by diabetes. Malondialdehyde levels in the liver homogenates of UD rats were higher than those of controls and were markedly reduced after melatonin treatment. Although no significant difference was observed with respect to antioxidant status, the superoxide dismutase activity tended to be higher in the UD rats than in the treated rats. Our findings showed that metatonin administration partially reduced liver injury in STZ-induced diabetic rats.Öğe Intrastromal versus subconjunctival anti-VEGF agents for treatment of corneal neovascularization: a rabbit study(Springernature, 2020) Üçgül, Rukiye Kılıç; Çelebi, Serdal; Yılmaz, Niyazi Samet; Bukan, Neslihan; Üçgül, Ahmet YücelObjective To determine whether subconjunctival or intrastromal administration of anti-VEGF agents is more effective on suture-induced corneal neovascularization (CoNV) in rabbits. Methods CoNV was induced in 48 eyes of 24 New Zealand white rabbits by using an 8/0 silk suture. On the 7th day after suturing, the rabbits were divided into four treatment groups as follows: six rabbits received subconjunctival bevacizumab (group 1), six rabbits received subconjunctival aflibercept (group 2), six rabbits received intrastromal bevacizumab (group 3) and six rabbits received intrastromal aflibercept (group 4). On the 7th and 14th days after suturing, the CoNV area was calculated by standardised analysis of photographs using the Image-J program. On the 14th day after suturing, all rabbits were sacrificed and then corneal tissue was harvested for the analysis of vascular endothelial growth factor (VEGF)-A, VEGF-B and placental growth factor (PIGF) levels. Results On the 7th day after suturing, CoNV areas were 17.10 +/- 2.98, 18.88 +/- 3.78, 17.36 +/- 4.52, 18.57 +/- 4.16 and 17.31 +/- 2.81 mm(2) in the groups 1-4 and control group, respectively. On the 7th day after intervention and removal of suture, CoNV areas were 4.85 +/- 1.99, 6.66 +/- 1.73, 2.83 +/- 1.08, 2.63 +/- 1.16 and 11.93 +/- 2.64 mm(2) in the group 1-4 and control group, respectively. CoNV area was reduced by 88.1% and 82.5% in eyes receiving intrastromal aflibercept and bevacizumab, respectively (both p < 0.001), and by 64.5% and 69.9% in eyes receiving subconjunctival aflibercept and bevacizumab, respectively (both p = 0.001). Conclusion Intrastromal anti-VEGF therapy regressed CoNV more effectively than subconjunctival therapy regardless of the type of anti-VEGF agent.Öğe Lipid peroxidation and scavenging enzyme levels in the liver of streptozotocin-induced diabetic rats(Natl Inst Science Communication-Niscair, 2003) Bukan, Neslihan; Sancak, Banu; Yavuz, Özlem; Koca, Cemile; Tutkun, Funda; Özçelikay, A. Tanju; Altan, NilgünIn this study, alterations in the liver antioxidant enzymes status and lipid peroxidation in short-term (8-weeks) and long-term (24-weeks) diabetic rats were examined. Glutathione peroxidase (GSH-Px) activity and malondialdehyde (MDA) levels were significantly increased, but superoxide dismutase (SOD) activity was significantly reduced in 8-weeks diabetic rats, compared to control. Catalase (CAT) activity, however, was found unchanged. In 24-weeks diabetic rats, while GSH-Px activity was unchanged, but SOD and CAT activities and MDA levels were significantly increased, compared to control. These results suggest that diabetes-induced alterations, in tissue antioxidant system may reflect a generalized increase in tissue oxidative stress. It can be concluded that lipid peroxidation and antioxidant enzyme levels are elevated in diabetic condition. Hence, diabetes mellitus, if left untreated, may. increase. degenerative processes. due. to accumulation of oxidative. free radicals.Öğe Matrix metalloproteinase-9 (MMP-9) in allergic nasal polyps(Elsevier Gmbh, Urban & Fischer Verlag, 2010) Buğdaycı, Güler; Kaymakçı, Mustafa; Bukan, NeslihanMatrix metalloproteinases (MMPs) are known to play important roles in the invasion of nasal mucosa by inflammatory cells through degradation of extracellular matrix. Matrix metalloproteinase-9 (MMP-9) is considered to play a role in the pathogenesis of nasal polyp. The aim of the present study was to compare plasma MMP-9 levels of patients with nasal polyp of different etiologic origins, those with allergic nasal polyp (ANP) and non-allergic nasal polyp (NANP). In all, 29 patients (20 NANP and 9 ANP) and 20 healthy subjects were included in this study. Plasma MMP-9 levels were measured using ELISA. Plasma MMP-9 levels were higher (p<0.05) in ANP patients than in NANP patients and controls. In the group with ANP, plasma MMP-9 levels showed a positive correlation (p<0.05) with eosinophil counts. Plasma MMP-9 levels of NANP patients and control groups were similar (p>0.05). Moreover, that the highest levels of MMP-9 were in ANP patients may indicate the usefulness of this parameter in differentiating between the different etiologic origins of nasal polyp. Further studies are required to elaborate on the relationship between MMP-9 levels and allergic reactions. (C) 2008 Elsevier GmbH. All rights reserved.Öğe Melatonin protects against epirubicin-induced cardiotoxicity(Elsevier Gmbh, 2007) Güven, Aysel; Yavuz, Özlem; Çam, Meryem; Ercan, Feriha; Bukan, Neslihan; Çomunoğlu, CemWe investigated the cytoprotective effect of melatonin in epirubicin-induced cardiotoxicity using four experimental groups of mate Wistar rats: untreated control rats, epirubicin-treated rats, epirubicin+melatonin-treated rats, and melatonin-treated rats. We examined the histopathological. and biochemical, effects of melatonin on the epirubicin-induced changes and measured the Levels of the lipid peroxication end-product (malondialdehyde, MDA), an indicator of nitric oxide (NO) synthesis (nitrite/nitrate production), and reduced glutathione (GSH) in the heart. We also studied the extracellular matrix components (fibronectin, laminin) in the heart. Vacuole formation, mitochondrial. deformation and degeneration, and disordered myofibrillary structures were detected ultrastructurally in the epirubicin-treated group. The degeneration was reduced in the heart tissues of the epirubicin+melatonin group. Epirubicin increased the nitrite/nitrate production, but did not change the MDA and GSH levels significantly. Melatonin treatment Lowered the nitrite/nitrate concentrations, while increasing the GSH levels, which exceeded the Levels in epirubicin+melatonin-treated rats. We conclude that the epirubicin increased the nitrozative stress, not the oxidative stress, in heart tissue, and the cardioprotective effect of melatonin was partially attributed to the suppression of epirubicin-induced nitrozative stress. These results suggest that melatonin partially protects against epirubicin-induced cardiotoxicity. (C) 2006 Elsevier GmbH. All rights reserved.Öğe Protective effect of melatonin on beta-cell damage in streptozotocin-induced diabetes in rats(Urban & Fischer Verlag, 2003) Yavuz, Özlem; Cam, Meryem; Bukan, Neslihan; Güven, Aysel; Sılan, FatmaThe aim of the present study was the evaluation of possible protective effects of melatonin against beta-cell damage in streptozotocin-induced diabetes in rats. Malondialdehyde levels and glutathione peroxidase activity were measured in pancreatic homogenates. Pancreatic beta-cells were examined by immunohistochemical methods. Streptozotocin was injected intraperitoneally at a single dose of 60 mg/kg for induction of diabetes. Melatonin (200 mug/kg/day, ip) was injected for 3 days prior to administration of streptozotocin; these injections were continued until the end of the study (4 weeks). Streptozotocin induced a significant increase in malondialdehyde levels (p < 0.01) and a significant decrease in glutathione peroxidase activity (p < 0.05) in pancreatic tissue. Degeneration of islet cells and weak immunohistochemical staining of insulin was observed in diabetic rats. Treatment of diabetic rats with melatonin markedly reduced malondialdehyde production (p < 0.05) and increased glutathione peroxidase activity (p < 0.01) without affecting hyperglycemia. Increased staining of insulin and preservation of islet cells were apparent in the melatonin-treated diabetic rats. These data suggest that melatonin treatment has a therapeutic effect in diabetes by reduction of oxidative stress and preservation of pancreatic beta-cell integrity.Öğe Protective effects of chronic melatonin treatment against renal injury in streptozotocin-induced diabetic rats(Blackwell Munksgaard, 2003) Çam, Meryem; Yavuz, Özlem; Güven, Aysel; Ercan, Feriha; Bukan, Neslihan; Üstündağ, NilThe aim of this study was to investigate the effects of melatonin as an antioxidant, on prevention and treatment of streptozotocin (STZ)induced diabetic renal injury in rats. Male Wistar rats were divided into four groups: ( 1) untreated, ( 2) melatonin-treated, ( 3) untreated diabetic (UD), ( 4) melatonin-treated diabetic ( MD). Experimental diabetes was induced by single dose ( 60 mg/kg, i.p.) STZ injection. For 3 days prior to administration of STZ, melatonin was injected ( 200 mug/kg/day, i.p.); these injections were continued until the end of the study ( 4 weeks). Malondialdehyde (MDA) levels as a marker of lipid peroxidation were significantly increased in the renal homogenates of UD animals and decreased after melatonin administration. The activity of the antioxidative enzyme glutathione peroxidase (GSH-Px) was significantly reduced in UD rats. Melatonin treatment reversed STZ-induced reduction of GSH-Px activity without having an effect on blood glucose. Upon histopathological examination, it was observed that the melatonin treatment prevented the renal morphological damage caused by diabetes. Upon immunohistochemical investigation, glomerular anti-laminin beta1 staining decreased in MD rats. Additionally, no tubular anti-IGF-1 staining was observed in melatonin-treated rats. In conclusion, chronically administered melatonin reduced renal injury in STZ-induced diabetic rats and thus it may provide a useful therapeutic option in humans to reduce oxidative stress and the associated renal injury in patients with diabetes mellitus.Öğe Serum oxidant and antioxidant levels in diesel exposed toll collectors(Wiley, 2004) Arbak, Peri; Yavuz, Özlem; Bukan, Neslihan; Balbay, Öner; Ülger, Füsün; Annakkaya, Ali NihatSerum Oxidant and Antioxidant Levels in Diesel Exposed Toll Collectors: Peri ARBAK, et al. Department of Chest Diseases, Abant Izzet Baysal University, Duzce School of Medicine, Turkey-it has been suggested that exposure to diesel exhaust may lead to adverse effects due to the generation of oxidants. To evaluate the end products of oxidative stress in DE exposure, toll collectors who are considered a high risk group in regard to occupational toxins were compared to controls who had office-based occupations in the same company in this cross sectional study. A total of 38 toll collectors constituted the study group. All subjects were male. The toll collectors and 29 controls were similar regarding age, smoking status and duration of work. All subjects underwent a clinical examination and an interviewer-administrated questionnaire regarding respiratory symptoms, past medical and occupational history, and pulmonary function tests were performed in all subjects. Serum malondialdehyde (MDA), nitrite+nitrate and vitamin E levels were measured. Toll collectors showed higher serum MDA (5.76 +/- 2.15 mumol/L vs. 3.07 +/- 0.76 mumol/L, p=0.0001) and nitrite+nitrate levels (96.50 +/- 45.54 mumol/L vs. 19.32 +/- 11.77 mumol/L, p=0.0001) than controls. Vitamin E levels were similar in toll collectors and controls (10.57 +/- 3.44 mg/L and 9.72 +/- 2.44 mg/L, respectively, p=0.267). There was no difference between groups in terms of the findings of clinical examinations and respiratory symptoms. In pulmonary function parameters, only peak expiratory flow (PEF) in toll collectors was significantly lower than that of controls (88.9% predicted and 104.2% predicted, respectively, p=0.012). In conclusion, we suggest that serum MDA and nitrite+nitrate levels may be used as biological markers of oxidative stress related to DE exposure, but prospective controlled clinical studies are necessary to clarify the possible association between concentrations of MDA and nitrite+nitrate and pulmonary diseases related to DE exposure.
