Person: KOÇ, MEHMET
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KOÇ
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MEHMET
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Publication Metadata only Histopathological changes and tumour necrosis factor-alpha, transforming growth factor-beta and tenascin expression in patients with primary type I membranoproliferative glomerulonephritis in remission(WILEY, 2009) ARIKAN, İZZET HAKKI; Arikan, Hakki; Koc, Mehmet; Cakalagaoglu, Fulya; Tuglular, Serhan; Ozener, Cetin; Akoglu, EmelAim: Primary type I membranoproliferative glomerulonephritis (MPGN) is a rare cause of glomerular disease with a high relapse rate and poor prognosis. The aim of this study was: (i) to evaluate the histopathological findings associated with remission; and (ii) to document the possible clinical and histopathological factors predicting relapses. Methods: Eleven type I MPGN patients (five men, six women; mean age, 38.8 +/-13.5 years) who were in remission for at least 1 year after the cessation of immunosuppressive drugs were re-biopsied. The intensity of immunostaining for tumor necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta 1, and tenascin was graded from 0 (no staining) to 3+ (maximum staining). Results: Mean baseline mesangial cellularity score and tubulointerstitial infiltration score were reduced and mesangial matrix expansion score was increased at protocol re-biopsies compared to baseline. The glomerular and tubulointerstitial staining scores for TGF-beta 1 and tenascin were higher than that of baseline. Reduced tubulointerstitial TNF-alpha expression was found in re-biopsy specimens compared to baseline. Patients have been followed for a mean time of 51.5 +/- 22.2 months after the protocol biopsy. Eight patients had a relapse. Mesangial cellularity score and glomerular tenascin expression at re-biopsy specimens were higher in relapsed patients compared to those without a relapse. Conclusion: Our study shows that mesangial cellularity and tubulointerstitial cell infiltration are reducing whereas mesangial matrix expansion, glomerular and tubulointerstitial TGF-beta 1 and tenascin expression are increasing with remission. The higher mesangial cell proliferation and glomerular tenascin scores in remission are associated with the development of relapse.Publication Metadata only Statin use is associated with lower inflammation and erythropoietin responsiveness index in hemodialysis patients(WILEY, 2011) KOÇ, MEHMET; Koc, Mehmet; Dogan, Cengiz; Arinsoy, Turgay; Tonbul, Zeki; Ayli, Deniz; Cirit, Mustafa; Sever, Mehmet Sukru; Yilmaz, Mehmet Emin; Unsal, Abdulkadir; Suleymanlar, Gultekin; Ok, Ercan; Basci, Ali; Yildiz, AlaatinPatients with end-stage renal disease are prone to inflammation and inflammation is related to erythropoietin-stimulating agent hyporesponsiveness and mortality in this population. Statins have been demonstrated to reduce cardiovascular mortality in selected populations of end-stage renal disease patients. These drugs have pleiotrophic effects such as anti-inflammation. In this retrospective analysis, we determined whether the use of statins improves inflammation and inflammation-related anemia in a cohort of hemodialysis patients. Data were analyzed from Fresenius Medical Care Dialysis Clinics in Turkey between 2005 and 2007. Seventy prevalent hemodialysis patients who were on statins at the start of the study and have been on statins during follow-up (statin users) and 1293 patients who were not on statin at the start of the study and had never been prescribed any lipid-modifying drugs during follow-up (statin nonusers) were included in the study. High-sensitive C-reactive protein levels were significantly decreased in statin users (1.50 +/- 1.49 vs. 1.33 +/- 1.11 mg/L, P=0.05) compared with nonusers (1.93 +/- 3.22 vs. 2.05 +/- 2.77 mg/L). Hemoglobin levels and the rate of erythropoietin-stimulating agent users were similar. However, the prescribed erythropoietin-stimulating agent dose (31.6 +/- 27.5 vs. 47.3 +/- 45.2 U/kg/week, P < 0.05) and the erythropoietin response index (2.90 +/- 2.73 vs. 4.51 +/- 4.48 U/kg/week/Hb, P=0.001) were lower in statin users compared with statin nonusers. On stepwise multiple regression analysis, gender, high-sensitive C-reactive protein, duration of hemodialysis, serum ferritin, and statin use were independent determinants of the erythropoietin responsiveness index. Our results suggest that statin treatment leads to lower inflammation and improves hematopoiesis in hemodialysis patients.Publication Metadata only Effect of low- and high-dose levothyroxine on thyroid nodule volume: a crossover placebo-controlled trial(BLACKWELL PUBLISHING LTD, 2002) YAVUZ, DİLEK; Koc, M; Ersoz, HO; Akpinar, I; Gogas-Yavuz, D; Deynell, O; Akalin, SOBJECTIVE The efficacy and the effective dose of levothyroxine suppressive therapy in the treatment of benign thyroid nodules are controversial. In this study, we aimed to determine the response of solitary thyroid nodules to low- or high-level TSH suppression in a placebo-controlled, randomized crossover trial. DESIGN Forty-nine patients with solitary thyroid nodules on palpation were randomized to high-level and low- level TSH suppression groups. In each group, patients were further randomized to placebo and active levothyroxine subgroups. Patients in each subgroup were crossed over to placebo or active levothyroxine at the end of the first year and were then followed up for an additional year. METHODS TSH levels were suppressed to 0.4-0.6 mIU/ml and less than or equal to0.01 mIU/ ml in the low-level and high-level TSH suppression groups, respectively. Nodule volumes were measured at baseline and every 6 months after the desired level of TSH was reached if the patients were in the active levothyroxine treatment group or every 6 months if they were in the placebo group. RESULTS In high-level TSH suppression groups, nodule volume decreased significantly at the end of the active treatment periods (4.99 +/- 2.02 ml vs. 3.20 +/- 1.50 ml, P < 0.01, in Group 1; and 3.72 &PLUSMN; 1.79 ml to 2.05 &PLUSMN; 0.64 ml, P < 0.001, in Group 2). In the low-level TSH suppression groups, nodule volume also decreased significantly at the end of the active treatment periods (4.43 +/- 1.76 ml vs. 3.04 +/- 1.32, P < 0.05, in Group 3; and 3.59 &PLUSMN; 0.89 ml to 2.22 &PLUSMN; 0.59 ml, P < 0.01, in Group 4). Nodule volumes regained their original volumes during the placebo treatment periods. The percentage decline in clinically relevant nodule volume reduction (greater than or equal to50%) was similar in the low- level and high-level TSH suppression groups. CONCLUSION Low- and high-level TSH suppression were equally effective in reducing nodule volume and thus, considering the complications of high-level TSH suppression, low- level TSH suppression should be used if one considers levothyroxine suppressive therapy to reduce thyroid nodule size.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 Metadata only Waist circumference is associated with carotid intima media thickness in peritoneal dialysis patients(SPRINGER, 2013) VELİOĞLU, ARZU; Asicioglu, Ebru; Kahveci, Arzu; Arikan, Hakki; Koc, Mehmet; Tuglular, Serhan; Ozener, Cetin IshakAtherosclerosis is responsible for the high mortality rate in end-stage renal disease patients. Defining risk factors for atherosclerosis may lead to reduction in cardiovascular disease through modification of these factors. Peritoneal dialysis (PD) patients are subjected to high glucose loads on a daily basis, which results in considerable weight gain and an increase in waist circumference (WC). WC as an indicator of abdominal obesity is a risk factor for atherosclerosis in the general population. Carotid artery intima media thickness (CIMT) measurement is a reliable method for the detection of early atherosclerosis. The aim of this study was to investigate the relationship between WC and CIMT and to define risk factors associated with CIMT in PD patients. Fifty-five PD patients and 40 healthy controls were included. Atherosclerosis was assessed using measurement of CIMT. Fasting blood was collected for analysis. Anthropometric parameters (age, weight, BMI, and WC) were measured. Peritoneal dialysis patients had higher WC (93.9 +/- A 1.7 vs. 87.3 +/- A 1.2 cm, p < 0.05) and CIMT (0.70 +/- A 0.02 vs. 0.57 +/- A 0.01 mm, p < 0.01) than the control group. On univariate analysis, age, WC, plaque formation, and D/P creatinine were positively correlated with CIMT, whereas residual renal function, albumin, ultrafiltration volume, and D/D0 glucose were negatively correlated. On multivariate analysis, only age, WC, and plaque formation showed correlation (p < 0.001). Carotid artery intima media thickness is associated with age, plaque formation, and WC in PD patients. WC measurement is a simple, inexpensive, reproducible, and reliable method of evaluating atherosclerosis risk in PD patients and should be assessed at every visit. Appropriate counsel should be provided to patients with greater WC who are deemed to be at risk for atherosclerosis.Publication Metadata only Elevated Plasma Levels of PAI-1 Predict Cardiovascular Events and Cardiovascular Mortality in Prevalent Peritoneal Dialysis Patients(TAYLOR & FRANCIS LTD, 2009) ARIKAN, İZZET HAKKI; Arikan, Hakki; Koc, Mehmet; Tuglular, Serhan; Ozener, Cetin; Akoglu, EmelBackground. Elevated plasminogen activator inhibitor-1 (PAI-1) levels are associated with increased cardiovascular (CV) risk in the general population. It has been shown that peritoneal dialysis (PD) patients have increased plasma levels of PAI-1. The aim of this study was to investigate whether PAI-1 independently predicted CV outcome in PD patients. Material and Methods. Seventy-two PD patients (53% females, mean age 49.9 +/- 16.1 years) were studied. Twelve patients who underwent kidney transplantation and 14 patients who transferred to hemodialysis during follow-up were excluded from the analysis. The remaining 46 patients (54% female, mean age 54 +/- 16 years, dialytic age 42 +/- 30 months) were followed a mean time of 45.4 +/- 19.4 months (range 8-71 months). Baseline PAI-1, clinical, and laboratory parameters were assessed in all patients. Survival analyses were made with Kaplan-Meier and Cox regression analysis, with all-cause mortality and CV mortality and CV events (CVEs) as clinical end points. Results. During the follow-up, 29 patients died (17 from CV causes), and 28 fatal and non-fatal CVEs were recorded. The patients were divided according to plasma PAI-1 levels (i.e., <= or >41 ng/mL). The significant independent predictors of all-cause of mortality were age (>60 years; p = 0.018), CRP (>5 mg/L; p = 0.015), and serum albumin (<3.5 g/L; p = 0.011). Multivariable Cox regression analysis showed that plasma PAI-1 >41 ng/mL was independently predictive of higher CV mortality (p = 0.021) and CVEs (p = 0.001). The only other independent predictor of CV mortality was only CRP (>5 mg/L; p = 0.008). Conclusions. Plasma levels of PAI-1 >41 ng/mL is a significant predictor of CV mortality and CVEs in PD patients.Publication Metadata only Baseline carotid intima-media thickness is associated with cardiovascular morbidity and mortality in peritoneal dialysis patients(WILEY, 2021) VELİOĞLU, ARZU; Asicioglu, Ebru; Velioglu, Arzu; Arikan, Hakki; Koc, Mehmet; Tuglular, Serhan; Ozener, CetinCarotid intima-media thickness (CIMT) is an early marker of atherosclerosis and is increased in peritoneal dialysis (PD) patients. Association of CIMT with cardiovascular disease (CVD) or mortality is less clear. Fibroblast growth factor-23 (FGF-23) is a hormone associated with vascular calcification, atherosclerosis, and mortality in the hemodialysis population. We investigated whether baseline CIMT and FGF-23 are associated with CVD and mortality in PD patients. Fifty-five PD patients were included. CVD was defined as ischemic heart disease, stroke, or peripheral artery disease. Intact FGF-23 was measured in plasma. CIMT was measured by ultrasonography. Twenty-one patients developed CVD and 12 died over 47.1 +/- 33.8 months. Patients with CVD were older (55.9 +/- 10.5 vs. 42.5 +/- 12.9 years, P < .01), had lower albumin (3.8 +/- 0.5 vs. 4.2 +/- 0.3 g/dL, P < .01) and higher CIMT (0.87 +/- 0.22 vs. 0.61 +/- 0.11 mm, P < .01). Patients with mortality were also older (53.5 +/- 11.5 vs. 45.8 +/- 13.8 years, P = .05), had lower albumin (3.7 +/- 0.6 vs. 4.1 +/- 0.3 g/dL, P < .01), higher CRP (15.0 +/- 8.5 vs. 7.6 +/- 8.4 mg/L, P < .01) and CIMT (0.9 +/- 0.3 vs. 0.6 +/- 0.1 mm, P < .01). Albumin and CIMT were associated with CVD and CIMT > 0.75 mm was associated with cardiovascular mortality. FGF-23 did not show any correlations. CIMT at baseline is associated with CVD and mortality in PD patients.Publication Metadata only Obestatin improves ischemia/reperfusion-induced renal injury in rats via its antioxidant and anti-apoptotic effects: Role of the nitric oxide(ELSEVIER SCIENCE INC, 2014) YEGEN, BERRAK; Koc, Mehmet; Kumral, Zarife Nigar Ozdemir; Ozkan, Naziye; Memi, Gulsun; Kacar, Omer; Bilsel, Serpil; Cetinel, Sule; Yegen, Berrak C.Obestatin was shown to have anti-inflammatory effects in several inflammatory models. To elucidate the potential renoprotective effects of obestatin, renal I/R injury was induced in male Sprague Dawley rats by placing a clamp across left renal artery for 60 min following a right nephrectomy. Clamp was released and the rats were injected with either saline or obestatin (10, 30, 100 mu g/kg). In some experiments, obestatin (10 mu g/kg) was administered with L-NAME (10 mg/kg) or L-Nil (0.36 mg/kg). Following a 24-h reperfusion, the rats were decapitated to measure serum creatinine and nitrite/nitrate levels, renal malondialdehyde (MDA), glutathione (GSH) levels and myeloperoxidase (MPO) activity and to assess cortical necrosis and apoptosis scores. Obestatin treatment reduced I/R-induced increase in creatinine levels, renal MPO activity and renal MDA levels, while renal GSH levels were significantly increased by obestatin. Histological analysis revealed that severe I/R injury and high apoptosis score in the kidney samples of saline-treated rats were significantly reduced and the cortical/medullary injury was ameliorated by obestatin. Expression of eNOS, which was increased by I/R injury, was further increased by obestatin, while serum NO levels were significantly decreased. iNOS inhibitor L-Nil reduced oxidative renal damage and improved the functional and histopathological parameters. I/R-induced elevation in eNOS expression, which was further increased by obestatin, was depressed by L-NAME and L-Nil treatments. The present data demonstrate that obestatin ameliorates renal I/R-injury by its possible anti-oxidative, anti-inflammatory and anti-apoptotic properties, which appear to involve the suppression of neutrophil accumulation and modulation of NO metabolism. (C) 2014 Elsevier Inc. All rights reserved.