Person: KOÇ, MEHMET
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KOÇ
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MEHMET
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Publication Open Access Circulating endothelial cells are associated with future vascular events in hemodialysis patients(ELSEVIER SCIENCE INC, 2005-03) KOÇ, MEHMET; Koc, M; Richards, HB; Bihorac, A; Ross, EA; Schold, JD; Segal, MSBackground. Endothelial dysfunction and injury are thought to have a key role in the pathogenesis of cardiovascular disease. We hypothesized that the presence of circulating endothelial cells, as a reflection of ongoing endothelial injury, might provide a novel means for predicting cardiovascular events in hemodialysis subjects who are known to be at marked increased risk for cardiovascular disease. Methods. Circulating endothelial cell number was determined in 29 hemodialysis patients who were then followed for vascular events for 470 172 days. In a second cohort of 44 hemodialysis patients, circulating endothelial cell number was correlated with markers of inflammation, namely high sensitivity C-reactive protein (hs-CRP), interleukin (IL)-6, IL-10, and monocyte chemoattractant protein-1 (MCP-1), and endothelial dysfunction, soluble vascular cellular adhesion molecule-1 (VCAM-1). Results. Seven of the 19 subjects with elevated circulating endothelial cells (defined as > 19 cells per mL) had cardiovascular (N = 5) or vascular (N = 5) events during follow-up, whereas no events occurred in subjects with a low number of circulating endothelial cells (less than or equal to19 CECs per mL) (P = 0.04 by Fisher Exact Test). In the second cohort, the number of circulating endothelial cells was independent of all markers of inflammation and endothelial dysfunction. Conclusion. In this hemodialysis population, an increase in circulating endothelial cells was found to predict the development of cardiovascular and vascular events, and to be independent of other known markers of inflammation or endothelial dysfunction. These studies suggest that circulating endothelial cells may be a novel way to assess endothelial health and cardiovascular risk. Further studies to investigate the utility of circulating endothelial cells in predicting cardiovascular risk are needed.Publication Open Access Acute Renal Failure due to Bladder Injury after Cesarean Section: Case Report and Review of the Literature(TURK NEFROLOJI DIYALIZ TRANSPLANTASYON DERGISI, 2019-11-05) AŞICIOĞLU, EBRU; Atas, Dilek Barutcu; Asicioglu, Ebru; Durgay, Meryem; Arikan, Hakki; Koc, Mehmet; Tuglular, Serhan; Ozener, CetinA 31-year-old woman who had an uncomplicated cesarean section five days prior to admission presented with abdominal distention. Evaluation revealed acute renal failure and abdominal ascites. Diagnostic paracentesis showed urinary ascites, which confirmed a bladder injury. The patient was conservatively treated by placement of a Foley catheter that resulted in complete resolution of the renal failure.Publication Open Access Toll-like receptor expression in monocytes in patients with chronic kidney disease and haemodialysis: relation with inflammation(OXFORD UNIV PRESS, 2011-03-01) AŞICIOĞLU, EBRU; Koc, Mehmet; Toprak, Ahmet; Arikan, Hakki; Odabasi, Zekaver; Elbir, Yesim; Tulunay, Aysin; Asicioglu, Ebru; Eksioglu-Demiralp, Emel; Glorieux, Griet; Vanholder, Raymond; Akoglu, EmelBackground. Inflammation is one of the main contributors to atherosclerosis in haemodialysis (HD) patients. Activation of Toll-like receptors (TLRs) leads to inflammatory response. In this study, we aimed to evaluate the expression of TLRs on monocytes and relate their expression with inflammation in chronic kidney disease (CKD) and HD patients. Methods. Thirty-four age- and gender-matched controls and stage 3-4 CKD patients and thirty-two HD patients were included in each study group. The effect of HD on the expression of Toll-like receptor-2 (TLR-2) and Toll-like receptor-4 (TLR-4) on CD14(+) monocytes was determined at the beginning (baseline), during (120 min) and following (300 min and 24 h) HD and compared with control and stage 3-4 CKD groups. The HD procedure was performed by using low-flux polysulphone dialysers. In addition, serum IL-6 levels were evaluated in both groups at baseline and after a HD session. Results. The percentage of CD14(+) monocytes expressing TLR-2 were similar in all of the study groups, whereas the percentage of CD14(+) monocytes expressing TLR-4 were significantly lower in both stage 3-4 CKD and HD patients at baseline than in controls. The mean fluorescence intensities (MFI) of TLR-2 were significantly lower in controls than in stage 3-4 CKD and HD patients at baseline. The MFI of TLR-4 was similar in all of the groups. The percentage of CD14(+) monocytes expressing TLR-2 did not change during and after HD. The MFI of TLR-2 decreased at 120 min of HD compared with baseline (1837 +/- 672 vs 1650 +/- 578, P < 0.05), and recovered back to baseline values at 300 min and at 24 h post-HD. MFI of TLR-4 increased at 24 h compared with baseline (941 +/- 294 vs 1087 +/- 441, P < 0.05). Serum IL-6 levels correlated with MFI of TLR-2 and TLR-4 in stage 3-4 CKD patients and in HD patients at baseline and after HD in univariate analysis. Stepwise multiple regression analysis revealed that MFI of TLR-2 was an independent determinant of serum IL-6 concentrations in stage 3-4 CKD and in HD patients at baseline, at 300 min and at 24 h post-HD. Conclusions. Our study demonstrates that TLR-2 is associated with the inflammatory response of non-dialysed and dialysed CKD patients.Publication Open Access The Intensity of PLA2R and C4d_x000D_ Immunoexpression in Primary_x000D_ Membranous Nephropathy(2019) FİLİNTE, DENİZ; Deniz FİLİNTE;Hakkı ARIKAN;Mehmet KOÇ;Handan KAYA;İshak Çetin ÖZENER;Gamze AKBAŞObjective: Antibodies against the phospholipase A2 receptor (PLA2R) on podocyte membranes result in the formation of immune complexes that cause loss of function of theglomerular basement membrane in primary membranous nephropathy (PMN). It has alsobeen demonstrated that there is a deposition of complement 4d (C4d) in the glomeruli inPMN. The present study aims to evaluate PLA2R and C4d immunoexpressions in PMN casesand search the correlation with the clinical parameters.Methods: In this study, clinicopathological data and paraffin-embedded specimens werecollected from 51 patients. The formalin-fixed paraffin-embedded tissues were stained usingroutine hematoxylin-eosin, periodic acid-Schiff, and silver methenamine stains and immunostained for anti-PLA2R and C4d. Ten normal kidney tissues and 10 focal segmental glomerulosclerosis (FSGS) cases were selected as controls for PLA2R and C4d immunoexpression.Results: Of the PMN cases, 51 (100%) cases were positive for PLA2R, including 15 (29%)cases that scored 2+, and 36 (71%) cases that scored 3+. Forty of the 51 cases (78%) werepositive for C4d. The percentages of cases staining positively for C4d, per scoring group,were as follows: 31 (61%) cases faintly (1+) positive and 9 (18%) cases moderately (2+)positive. No strong positivity was observed. All of the control cases (100%) were negativefor PLA2R and C4d. There was no statistically significant difference between the intensity ofthe staining of PLA2R and the staining of C4d, proteinuria levels, creatinine levels, and complement 3 (C3) positivity. Similarly, there was no statistically significant difference betweenthe intensity of the staining of C4d and proteinuria levels, creatinine levels, and C3 positivity.Conclusion: Immunohistochemical detection of PLA2R and C4d is a safe and easy methodfor the diagnosis of PMN. In cases where fresh tissue is not available for the detection of IgGand C3 using the immunofluorescence method, positivity for PLA2R and C4d with immunohistochemistry may be beneficial for the diagnosis of PMN.Publication Open Access The potency of obestatin in improving kidney functions and apoptosis in rats with cisplatin-induced acute kidney injury(2022-01-01) ÖZDEMİR KUMRAL, ZARİFE NİGAR; BULUT, ALİSİNA; ÖZKAN YENAL, NAZİYE; YEGEN, BERRAK; KOÇ, MEHMET; ÖZDEMİR KUMRAL Z. N. , BULUT A., Üzülmez B., Vezirhüyük M., Kök Z., ÖZKAN YENAL N., YEGEN B., KOÇ M.© 2022 Marmara University Press.Cisplatin (CP), which is the most commonly used anticancer agent to treat several solid tumors, may cause acute kidney injury (AKI) as the major limiting factor for its clinical use. Obestatin (OB) is a ghrelin gene-derived peptide produced in several tissues and has shown anti-oxidant, anti-apoptotic, and anti-inflammatory effects in many experimental models. This study investigated the effect of OB treatment on nephrotoxicity induced by CP. Rats were divided into 4 groups as two control (1 ml/kg, saline, intraperitoneal (ip), single dose) and two CP-induced (7 mg/kg, ip, single dose) AKI groups (8 rats in each group). Immediately after the CP injection and the following two days, injections of OB (10 µg/kg, ip) were performed. Rats were decapitated at the end of 72 hours. Blood and kidney tissue samples were taken for biochemical and histopathological measurements. The results of the present study revealed that serum creatinine and BUN levels were significantly increased in the CP-induced AKI group when compared to the control group. Treatment with OB improved kidney functions and ameliorated renal oxidative injury and maintained oxidative balance in the CP-induced AKI model, which was revealed by elevated malondialdehyde and depleted glutathione levels. TUNEL scores also demonstrated that CP increased the apoptotic response, while OB treatment abolished it. CP-induced medullary and cortical injuries were also partially reversed by OB treatment. Thus, our findings show that OB alleviates CP-induced nephrotoxicity in rats through the abolishment of oxidative stress and apoptosis.Publication Open Access Night-time blood pressure load is associated with higher left ventricular mass index in renal transplant recipients(NATURE PUBLISHING GROUP, 2003-04) KOÇ, MEHMET; Toprak, A; Koc, M; Tezcan, H; Ozener, IC; Oktay, A; Akoglu, EThe absence of nocturnal fall in blood pressure (BP) is named as nondipper status, which has been shown to be an additional risk factor for the development of left ventricular hypertrophy and cardiovascular events in several high-risk groups. The aim of this study was to determine the influences of the nondipper status and nocturnal blood pressure loads on left ventricular mass index (LVMI) in renal transplant recipients. A total of 35 nondiabetic renal transplant recipients were included into the study. A 24-h ambulatory blood pressure monitoring (ABPM) was performed for all recipients. The nondipper status was defined as either an increase in night-time mean arterial pressure (MAP) or a decrease of no more than 10% of daytime MAP. LVMI was measured by using two-dimensional guided M-mode echocardiography. The night-time systolic blood pressure (SBP) load was defined as the percentage of the time, during which SBP exceeded 125 mmHg during night time. The nondipping was common among renal transplant recipients, of whom 60% were nondipper in our study. LVMI was significantly higher in the nondipper group vs the dipper group (133 +/- 35 g/m(2) VS 109 +/- 26 g/m(2), P= 0.04). A fall in MAP at night time was 14.5 +/- 4.3% in the dipper group, while it was 1.4 +/- 6.1% in the nondipper group (P< 0.001). On stepwise multiple regression analysis, night-time SBP load and haemoglobin were independent predictors of LVMI (R-2 = 0.53). In conclusion, nondipping is common after renal transplantation. Night-time SBP load and low haemoglobin are closely related to the increase in LVMI in renal transplant recipients. ABPM may be a more useful tool in optimizing treatment strategies to reduce cardiovascular events in renal transplant recipients.Publication Open Access Inferior vena cava diameter determines left ventricular geometry in continuous ambulatory peritoneal dialysis patients: an echocardiographic study(OXFORD UNIV PRESS, 2003-10-01) KOÇ, MEHMET; Toprak, A; Koc, M; Tezcan, H; Ozener, IC; Akoglu, E; Oktay, ABackground. Changes in left ventricular (LV) geometry are frequent in patients with continuous ambulatory peritoneal dialysis (CAPD). Geometric adaptation of LV to various stimuli was reported to have adverse prognosis. This study aimed to identify independent risk factors, which contribute to the development of LV geometric remodelling in CAPD patients. Methods. The left ventricles of 69 CAPD patients were classified echocardiographically into four different geometric patterns on the basis of LV mass and relative wall thickness. With respect to volume factor, we measured inferior vena cava (IVC) diameter and its decrease on deep inspiration [collapsibility index (CI)] by echocardiography. We modelled a stepwise multiple regression analysis to determine the predictors of LV geometry. Results. All four geometric models of LV were identified in our group of 69 CAPD patients. Eccentric left ventricular hypertrophy (eLVH) was observed in 32 (46%), concentric LVH (cLVH) in 19 (28%), normal geometry (NG) in 10 (14%) and concentric remodelling (CR) in eight (12%) CAPD patients. Mean IVC index of the eLVH group (10.72 +/- 2.19 mm/m(2)) was significantly higher than corresponding indexes of NG (7.90 +/- 1.54 mm/m(2)), CR (8.51 +/- 1.28 mm/m(2)) and cLVH (8.04 +/- 2.00mm/m(2)) groups (P < 0.001 for each comparisons). The eLVH group also had significantly lower mean CI value (0.48 +/- 0.11) than CR (0.58 +/- 0.09) and cLVH (0.57 +/- 0.07) groups (ANOVA P=0.008). Stepwise multiple regression analysis revealed that IVC index, CI and haemoglobin were the independent predictors of LV geometric stratification (R-2 =0.36, P < 0.001). Conclusion. Hypervolaemia, identified by IVC index and CI, and anaemia contribute independently to LV geometry in CAPD patients. Echocardiography as a non-invasive tool is not only useful to determine LV geometry, but also to assess the volume status of CAPD patients.Publication Open Access Earthquakes and crush syndrome casualties: Lessons learned from the Kashmir disaster(ELSEVIER SCIENCE INC, 2007-01) KOÇ, MEHMET; Vanholder, R.; van der Tol, A.; De Smet, M.; Hoste, E.; Koc, M.; Hussain, A.; Khan, S.; Sever, M. S.Major earthquakes may provoke a substantial number of crush casualties complicated by acute kidney injury (AKI). After the 1988 Armenian earthquake, the International Society of Nephrology (ISN) established the Renal Disaster Relief Task Force (RDRTF) to organize renal care in large disastersPublication Open Access Perirenal haematoma as the presenting feature of polyarteritis nodosa: one more case from Turkey(OXFORD UNIV PRESS, 1998-03-01) KOÇ, MEHMET; Bihorac, A; Ozener, C; Koc, M; Akoglu, EPublication Open Access Uncontrolled hypertension due to volume overload contributes to higher left ventricular mass index in CAPD patients(OXFORD UNIV PRESS, 2002-09-01) KOÇ, MEHMET; Koc, M; Toprak, A; Tezcan, H; Bihorac, A; Akoglu, E; Ozener, ICBackground. Hypertension (HT) is common in patients on continuous ambulatory peritoneal dialysis (CAPD) and is responsible for increased cardiovascular morbidity and mortality. In this study, we aimed to determine the prevalence of 'uncontrolled HT' during background therapy in CAPD patients by using office measurements and ambulatory blood pressure monitoring (ABPM). We further determined whether intravascular volume status, assessed by inferior vena cava diameter (IVCD) index, contributes to higher blood pressure (BP) and increased left ventricular mass index (LVMI). Methods. Seventy-four CAPD patients were included in the final analysis. All patients underwent echo-cardiographic examination and received ABPM. Patients undergoing CAPD were categorized into two groups: 'uncontrolled HT' (Group A) and 'normotensive and controlled HT' (Group 13). Intravascular volume status was determined using the IVCD index and collapsibility index (CI) on the same day as ABPM. Results. The prevalence of HT was 84% when using office measurements and 82% when using daytime ABPM. Daytime BP was 147/92 mm Hg by office measurements and 145/91 mm Hg by ABPM (P>0.05). The prevalence of 'uncontrolled HT' measured by ABPM was 73% (n = 54). Patients with uncontrolled HT (Group A) were taking more antihypertensive medications than patients with 'normotension and controlled HT' (Group B, n = 20; 1.0+/-0.8 vs 0.5+/-0.7, P=0.008). The IVCD index was higher in Group A 2 than in Group B (9.2+/-2.1 vs 7.7+/-1.9 mm/m(2), P=0.007). There was no correlation between IVCD index and office BP, ABPM measurements or LVMI. The LVMI was also higher in Group A than in Group B (145+/-39 vs 118+/-34g/m(2), P<0.01). Stepwise multiple regression analysis revealed that 24 It diastolic BP and haemoglobin were independent determinants of LVMI. Conclusion. Uncontrolled HT on background therapy is highly prevalent among volume overloaded CAPD patients. Further long-term prospective studies examining effects of salt restriction and ultrafiltration on BP control and left ventricle wall thickness are warranted.