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    Accelerated atherosclerosis in haemodialysis patients; correlation of endothelial function with oxidative DNA damage
    (Oxford Univ Press, 2012) Kaya, Yuksel; Ari, Elif; Demir, Halit; Soylemez, Nihat; Cebi, Aysegul; Alp, Hakan; Bakan, Ebubekir
    Background. Accelerated atherosclerosis is the major cause of mortality in patients on chronic haemodialysis (HD). The aim of this study was to evaluate the relationship between oxidative DNA damage [8-hydroxy-2'-deoxyguanosine/deoxyguanosine ratio (8-OHdG/dG ratio)], oxidative stress biomarkers and endothelial function in HD patients as an indicator of atherosclerosis. Methods. Forty-four chronic HD patients without known atherosclerotic disease and 55 age- and sex-matched healthy individuals were included in the study. Plasma malondialdehyde (MDA) levels and 8-OHdG/dG ratio were determined as oxidative stress markers. Superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities were measured as antioxidants. Endothelial function was assessed by ultrasonography. Results. 8-OHdG/dG ratio and MDA levels were higher in HD patients than controls while SOD and GPx activities were lower in HD patients compared to controls. Flow-mediated dilatation FMD% in HD patients were lower than the control group (7.28 +/- 0.79 versus 11.18 +/- 0.82, P < 0.001). There was a significant negative correlation between FMD% and 8-OHdG/dG ratio (r = -0.678, P < 0.01) and MDA levels (r = 0.517, P < 0.01), while there was a significant positive correlation between FMD% and SOD (r = 0.538, P < 0.01) and GPx levels (r = 0.720, P < 0.01). Conclusions. Our data have demonstrated that HD patients exhibit increased oxidative DNA damage and decreased antioxidant activity. We propose that endothelial function is negatively correlated with 8-OHdG/dG ratio and positively correlated with antioxidant enzymes. To our knowledge, this is the first study to demonstrate the inverse relationship between endothelial function and plasma oxidative DNA damage in HD patients.
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    Serum cadmium levels are independently associated with endothelial function in hemodialysis patients
    (Springer, 2012) Kaya, Yuksel; Ari, Elif; Demir, Halit; Gecit, Ilhan; Beytur, Ali; Kaspar, Cigdem
    Hemodialysis (HD) patients are at risk of deficiency of essential trace elements and excess of toxic trace elements. The aim of the study was to evaluate the relation between the serum levels of some trace elements and heavy metals (iron, zinc, manganese, copper, magnesium, cobalt, cadmium, and lead) and endothelial function in HD patients. Forty-eight chronic HD patients without known atherosclerotic disease and 42 age- and sex-matched healthy individuals were included in the study. The serum levels of trace elements (iron, zinc, manganese, copper, and magnesium) and heavy metals (cobalt, cadmium, and lead) were measured by Atomic Adsorption Spectrophotometer (UNICAM-929). The serum levels of iron, zinc, and manganese were lower, and levels of copper, magnesium, cobalt, cadmium, and lead were higher in HD patients compared to controls. Flow-mediated dilatation (FMD %) in HD patients was lower than that in the control group (7.27 +/- A 0.76 vs. 11.29 +/- A 0.82, P < 0.001). There was a significant negative correlation between FMD % and serum levels of cobalt (r = -0.313, P = 0.03) and cadmium (r = -0.524, P < 0.01). A linear regression analysis showed that serum cadmium levels were still significantly and negatively correlated with FMD % (regression coefficient = -0.526, P < 0.001). We first demonstrated that serum cadmium levels independently predict endothelial function in HD patients without known atherosclerotic disease.