Browsing by Author "Karahan, M."

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Increased Oxidative Stress in Living Kidney Donors: Correlation of Renal Functions With Antioxidant Capacity
(Elsevier Science inc, 2017) Yildirim, M.; Karahan, M.; Kucuk, H. F.; Demir, T.; Demir, H.; Turan, H.; Ari, E.
Background. Substantial attention has recently been paid to the possibility of an increased risk of chronic kidney disease (CKD) in living kidney donors. It has been demonstrated that CKD patients suffer from increased oxidative stress, which have been reported to show a strong association with several clinical problems such as accelerated atherosclerosis. The purpose of the current cross-sectional, single-center study was to evaluate the relationship between renal functions of living kidney donors and systemic oxidative stress. Methods. A total of 55 living kidney donors operated at least 1 year ago and 40 age and sex-matched healthy individuals were enrolled in this study. Plasma malondialdehyde (MDA) levels were determined as oxidative stress marker. Superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities were measured as antioxidants. Renal function parameters and proteinuria were also assessed. Results. Mean serum creatinine levels were higher (P = .022) and 24-hour creatinine clearance was lower (P = .016) in living kidney donors compared with healthy controls. Serum MDA levels were higher (P = .034), and SOD and GPx activities were lower (P = .023 and P < .001, respectively). There was a significant positive correlation between serum GPx activity and 24-hour creatinine clearance levels (r = 0.524, P < .01). A linear regression analysis showed that serum GPx activity was still significantly and positively correlated with creatinine clearance (regression coefficient = 0.416, P < .001). Conclusion. Our data demonstrated that living kidney donors exhibit slightly reduced kidney function, increased oxidative stress, and decreased antioxidant activity. We propose that 24-hour creatinine clearance is positively correlated with antioxidant enzyme GPx. To our knowledge, this is the first study to demonstrate the association between renal functions and antioxidant activity in kidney donors.
Oxidative Dna Damage Is Increased in Living Kidney Donors
(Elsevier Science inc, 2019) Karahan, M.; Yildirim, M.; Kucuk, H. F.; Turunc, V; Demir, H.; Salturk, C.; Ari, E.
Background. Long-term consequences of donor nephrectomy might be reduced kidney function, increased risk for cardiovascular disease, and impaired quality of life. The purpose of the current cross-sectional study was to evaluate the relationship between clinical, laboratory, and donation-specific outcomes of living kidney donors and systemic oxidative DNA damage. Methods. We conducted a cross-sectional study and assessed retrospectively pre- and postdonation data from 60 donors who donated between 2010 and 2015. Plasma malondialdehyde levels and 8-hydroxy-20-deoxyguanosine/deoxyguanosine ratio (8-OHdG/dG ratio) were determined as oxidative stress markers. Catalase, carbonic anhydrase, and paraoxonase (PON) activities were measured as antioxidants. Results. Approximately 3 years after donation, the hypertensive donor ratio was 12%, and 11% of the donors had glomerular filtration rate <60 mL/min/1.73 m(2). Mean serum urea (P =.001) and serum creatinine levels (P =.001) were increased; creatinine clearance level (126.2 +/- 35.5 vs 94.6 +/- 26.8, P =.001) was decreased in the postdonation period. There was a significant positive correlation between predonation serum urea and 8-0HdG/dG ratio (r = 0.338, P =.016) and predonation serum creatinine and 8-0HdG/dG ratio (r = 0.442, P =.001), while there was a significant negative correlation between serum creatinine and PON activity (r = -0.545, P <.001). Conclusion. Our data have demonstrated that kidney donors exhibit increased oxidative DNA damage and decreased antioxidant activity. We propose that predonation serum creatinine is positively correlated with 8-0HdG/dG ratio and negatively correlated with antioxidant PON activity. This is the first study to demonstrate that plasma oxidative DNA damage increases in healthy kidney donors.