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Featured researches published by Hakki Yilmaz.


Renal Failure | 2014

Relationship between late arteriovenous fistula (AVF) stenosis and neutrophil–lymphocyte ratio (NLR) in chronic hemodialysis patients

Hakki Yilmaz; Alper Bozkurt; Muzaffer Cakmak; Huseyin Tugrul Celik; Mukadder Ayse Bilgic; Nuket Bavbek; Ali Akcay

Abstract Objectives: Primary cause of late arteriovenous fistula (AVF) dysfunction is venous stenosis as result of neointimal hyperplasia. The mechanism of AVF stenosis is not exactly understood. But inflammation is a contributing factor for development of AVF stenosis. Neutrophil–lymphocyte ratio (NLR) reflects systemic inflammation, and it was investigated in many diseases. The aim of this study was to investigate the relationship between NLR and AVF stenosis in chronic hemodialysis patients. Materials and methods: Of 593 patients applied to the department of interventional radiology between January 2011 and November 2012, a total of 108 patients meeting the appropriate criteria were included in this study. All patients were assessed with Color Doppler ultrasonography and then digital subtraction angiography was used for the patients with abnormal results. Sixty-four patients were classified as patients with AVF stenosis (group 1) and 44 patients without AVF stenosis (group 2). Routine biochemical and complete blood count values measured six months ago were recorded for all patients. Results: Mean NLR (3.47 ± 0.46 vs. 2.27 ± 0.22; p < 0.001) was higher in group 1 compared to group 2, whereas high-density lipoprotein (HDL; 31.8 ± 12.6 mg/dL vs. 51.5 ± 11.9 mg/dL; p < 0.001) was lower in group 1. NLR level was correlated with degree of AVF stenosis (r = 0.625; p < 0.01). Receiver operating characteristic curve analysis showed that NLR (optimal-cut-off = 2.70) was a useful parameter in prediction of AVF stenosis (AUC = 0.893, sensitivity = 98.4% and specificity = 75%; p < 0.001). NLR level and HDL < 30 mg/dL in logistic regression analysis are independent predictors of AVF stenosis. Conclusions: For hemodialysis patients with increased level of NLR and decreased level of HDL, regular monitoring with regard to the development of AVF stenosis may be beneficial. Our study suggests that the mechanism of AVF stenosis might have similarities to that of atherosclerosis.


Clinical and Experimental Hypertension | 2016

Serum levels of endocan correlate with the presence and severity of pre-eclampsia.

Muzaffer Cakmak; Hakki Yilmaz; Esra Bağlar; Tahir Darcin; Osman Inan; Aynur Aktas; Huseyin Tugrul Celik; Ozhan Ozdemir; Cemal Atalay; Ali Akcay

Abstract Background: Endocan, a cysteine-rich dermatan sulfate proteoglycan expressed by endothelial cells, is seemed to be a new biomarker for endothelial dysfunction. Pre-eclampsia (PE) is characterized by the new onset of hypertension, proteinuria after 20 weeks of gestation, placental vascular remodeling, systemic vascular inflammation and endothelial dysfunction. The aim of this study was to investigate the relationship of PE and its severity with serum endocan levels. Methods: A cross-sectional study was performed. Serum was collected from women with PE and normotensive controls. Serum endocan and tumor necrosis factor alpha (TNF-α) concentrations were measured by a specific enzyme linked immunosorbent assay. Results: Patients with PE had significantly higher median (interquartile range) endocan and mean TNF-α concentrations than controls [20.04 (12.26) ng/mL vs 15.55 (6.19) ng/mL, p < 0.001 for endocan; 26.49 ± 12.14 pg/mL vs 14.62 ± 5.61 pg/mL, p < 0.001 for TNF-α; respectively]. Serum endocan concentrations were positively correlated with systolic blood pressure (r = 0.618, p < 0.001), diastolic blood pressure (r = 0.608, p < 0.001), the amount of 24-h proteinuria (r = 0.786, p < 0.001) and TNF-α (r = 0.474, p < 0.001) in women with PE. In subgroup analysis, patients with severe PE had significantly higher endocan concentrations than those with mild PE. Receiver operating characteristic analysis of endocan was used to identify the patients with PE and also discriminating between mild and severe PE. Conclusion: Serum endocan concentrations were significantly elevated in women with PE versus normotensive controls, and concentrations seem to be associated with the severity of the disease.


Korean Circulation Journal | 2015

Association between Red Blood Cell Distribution Width and Coronary Artery Calcification in Patients Undergoing 64-Multidetector Computed Tomography

Özgül Malçok Gürel; Muhammed Bora Demircelik; Mukadder Ayse Bilgic; Hakki Yilmaz; Ömer Çağlar Yılmaz; Muzaffer Cakmak; Beyhan Eryonucu

Background and Objectives The red blood cell distribution width (RDW) has been found to be associated with cardiovascular morbidity and mortality. The objective of this study was to determine whether the RDW measures are associated with the coronary artery calcification score (CACS) in patients who did not present with obvious coronary heart disease (CHD). Subjects and Methods A total of 527 consecutive patients with a low to intermediate risk for CHD but without obvious disease were enrolled in this study. The study subjects underwent coronary computerized tomography angiography and CACS was calculated. The patients were divided into two groups based on CACS: Group I (CACS≤100) and Group II (CACS>100). The two groups were compared in terms of classic CHD risk factors and haematological parameters, particularly the RDW. Results Group I patients were younger than Group II patients. The Framingham risk score (FRS) in patients of Group II was significantly higher than that in patients of Group I. Group II patients had significantly elevated levels of haemoglobin, RDW, neutrophil count, and neutrophil/lymphocyte ratio compared with Group I patients. CACS was correlated with age, RDW, and ejection fraction. In the multivariate analysis, age, RDW, and FRS were independent predictors of CACS. Using the receiver-operating characteristic curve analysis, a RDW value of 13.05% was identified as the best cut-off for predicting the severity of CACS (>100) (area under the curve=0.706). Conclusion We found that the RDW is an independent predictor of the CACS, suggesting that it might be a useful marker for predicting CAD.


Journal of Investigative Medicine | 2015

Is Kidney Injury Molecule 1 a Valuable Tool for the Early Diagnosis of Contrast-Induced Nephropathy?

Derya Akdeniz; Huseyin Tugrul Celik; Fatmanur Hacievliyagil Kazanci; Hakki Yilmaz; Serkan Yalcin; Mukadder Ayse Bilgic; Nuket Bavbek Ruzgaresen; Ali Akcay; Beyhan Eryonucu

Aim/Scope Contrast-induced nephropathy (CIN) is a common complication of diagnostic/therapeutic procedures. Serum creatinine levels are sensitive but often lead to diagnostic delays in acute kidney injury and potential misclassification of actual injury status. Kidney injury molecule (KIM-1) is a novel early marker of acute kidney injury. The aim of our study was to evaluate the KIM-1 levels in patients with CIN. We performed a single-center, nested case-control study. Materials and Methods Three thousand two hundred patients who had undergone coronary angiography were included in the study. Thirty-two patients were diagnosed with CIN. Twenty patients who had undergone coronary angiography but did not have CIN were evaluated as a control group (n = 20). The diagnosis of CIN was performed according to the KDIGO 2012 Acute Kidney Injury Guideline criteria. Urinary KIM-1 levels were measured by enzyme-linked immunosorbent assay before as well as on the 6th and 48th hours of contrast exposure. Serum creatinine levels were measured before as well as on the 24th and 48th hours after angiographic procedure. Results We demonstrated that KIM-1 levels increased in the patients with CIN significantly on the sixth hour when compared with the baseline (P < 0.01; median levels, 0.27 and 0.70 mg/dL) but not in the controls (P = 0.107). The precontrast and 48th-hour KIM-1 levels were median ones and were also significantly different (P = 0.001, the median levels were 0.27 and 0.60 mg/dL, respectively). Conclusions Because creatinine is a sensitive but a late marker of CIN, KIM-1 may be used for early diagnosis and early initiation of treatment and may reduce risk for morbidity.


Central European Journal of Urology 1\/2010 | 2016

Melatonin protects kidney against apoptosis induced by acute unilateral ureteral obstruction in rats.

Mehmet Erol Yildirim; Hüseyin Badem; Muzaffer Cakmak; Hakki Yilmaz; Bahadır Kösem; Omer Faruk Karatas; Reyhan Bayrak; Ersin Cimentepe

Introduction To investigate whether there was a protective effect of melatonin on apoptotic mechanisms after an acute unilateral obstruction of the kidney. Material and methods A total of 25 rats consisting of five groups were used in the study, designated as follows: Group 1: control, Group 2: sham, Group 3: unilateral ureteral obstruction treated with only saline, Group 4: unilateral ureteral obstruction treated with melatonin immediately, and Group 5: unilateral obstruction treated with melatonin one day after obstruction. Melatonin was administered as a 10 mg/kg dose intraperitoneally. The kidneys were evaluated according to the apoptotic index and Ki-67 scores. Results Comparison of all obstruction groups (Group 3, 4, and 5), revealed that the apoptotic index was significantly higher in Groups 1 and 2. Despite melatonin reduced apoptotic mechanisms in Groups 4 and 5, there was no significant difference between Groups 4 and 5 in terms of the reduction of apoptosis. However, the reduction of apoptosis in the melatonin treated group did not decrease to the level of Groups 1 and 2. Conclusions Despite melatonin administration, which significantly reduces the apoptotic index occurring after acute unilateral ureteral obstruction, the present study did not observe a return to normal renal histology in the obstruction groups.


Renal Failure | 2014

Correlation between iron stores and QTc dispersion in chronic ambulatory peritoneal dialysis patients

Nuket Bavbek; Hakki Yilmaz; Hacı Kemal Erdemli; Yusuf Selcuki; Murat Duranay; Ali Akcay

Abstract Aim: We aimed to investigate the QT dispersion and corrected QT (QTc) dispersion which are suggested as the signals of ventricular arrhythmias, in patients on maintenance CAPD and to evaluate the correlation between iron stores and these electrocardiographic parameters. Materials and method: Fifty-eight patients on maintenance CAPD and 19 healthy age- and sex-matched adults without cardiac disease were included. The PD patients were divided into two groups according to whether their computerized measurements of QTc dispersion were longer than 65 ms. Results: Although QT interval was statistically significantly shorter in control group (34 ± 28 vs. 43 ± 34 ms; p < 0.05), there was no significant difference in regards to the QTc, QT dispersion and QTc dispersion between two groups. PD patients with QTc dispersion longer than 65 ms had higher levels of serum ferritin (p = 0.038) and transferrin saturation (TSAT; p = 0.022) than the others. QTc dispersion were positively correlated with ferritin (r = 0.469, p < 0.01) and TSAT (r = 0.430, p < 0.01) in CAPD patients. Conclusion: Although prolonged QTc, QT dispersion and QTc dispersion were suggested as the markers of ventricular arrhythmias we did not find any significant difference in regards to these parameters between control patients and CAPD patients. But the high body iron stores in these patients increase the risk of increased QT dispersion. The concern over iron overload in dialysis patients is not only because of its oxidative toxicity, but also its precipitation of arrhythmias, which may be measured by the surrogate marker of QTc dispersion.


Renal Failure | 2014

CA 125 levels and left ventricular function in patients with end-stage renal disease on maintenance hemodialysis

Hakki Yilmaz; Özgül Malçok Gürel; Huseyin Tugrul Celik; Enes Şahiner; Mehmet Erol Yildirim; Mukadder Ayse Bilgic; Nuket Bavbek; Ali Akcay

Abstract Purpose: The aim of this study was to analyze associations between serum cancer antigen 125 (CA 125) levels and left ventricular (LV) function in patients with end-stage renal disease on maintenance hemodialysis (HD). Methods: CA 125 levels, pro-brain natriuretic peptide (pro-BNP) and biochemical parameters were measured, and echocardiography was performed for 110 patients and 47 healthy controls. Results: The mean CA 125 level in patients, 38.78 ± 35.48 U/mL, was significantly higher than that found in healthy controls (9.20 ± 4.55 U/mL; p = 0.003). Patients with elevated CA 125 levels (n = 40) had significantly lower levels of albumin and reduced relative wall thickness, LV ejection fraction (EF) and fractional shortening but significantly higher levels of pro-BNP and a greater left ventricular end-diastolic diameter (LVEDd) and -systolic diameter (LVESd). CA 125 levels were positively correlated with pro-BNP (r = 0.596, p < 0.05) and C-reactive protein (CRP) levels (r = 0.439, p < 0.05), as well as LVEDd (r = 0.599, p < 0.001), LVESd (r = 0.750, p < 0.001) and LV mass index (r = 0.378, p < 0.05). In contrast, serum CA 125 levels were negatively correlated with albumin (r = −0.513, p < 0.05) and hemoglobin (r = −0.475, p < 0.05) as well as the EF (r = −0.878, p < 0.0001). A depressed EF (β = −1.121, p < 0.0001) and increased CRP levels (β = 0.247, p = 0.035) were independent predictors of high CA 125 levels in the whole group in the multivariate-model. Conclusions: Our study is the first to demonstrate an association between serum CA 125 levels and LV systolic dysfunction via inflammation in patients on maintenance HD.


Renal Failure | 2016

Circulating irisin levels reflect visceral adiposity in non-diabetic patients undergoing hemodialysis

Hakki Yilmaz; Muzaffer Cakmak; Tahir Darcin; Osman Inan; Enes Sahiner; Canan Demir; Aynur Aktas; Mukadder Ayse Bilgic; Ali Akcay

Abstract Background: Recent evidence suggests that increased visceral adiposity is a strong independent risk factor for cardiovascular death and all-cause mortality in hemodialysis (HD) patients. Irisin, which is a novel myokine, can play critical roles in diabetes and adiposity. The purpose of our study was to investigate whether serum irisin levels are associated with body mass index, waist circumference (WC), and total fat mass in non-diabetic patients undergoing maintenance HD. Methods: This cross-sectional study included 108 non-diabetic HD patients and 40 age- and sex-matched apparently healthy subjects. Serum irisin concentrations were determined using an enzyme-linked immunosorbent assay. Body fat composition (TBF-410 Tanita Body Composition Analyzer) was measured and calculated. Results: Serum irisin levels did not differ between HD patients and the healthy controls (523.50 ± 229.32 vs. 511.28 ± 259.74, p = 0.782). Serum irisin levels were associated with age (r = 0.314; p =0.006), HOMA-IR (r = 0.472; p = 0.003), WC (r = 0.862; p < 0.001), and total fat mass (r = 0.614; p < 0.001). In multivariate regression analysis, WC (β = 1.240, p < 0.001) and total fat mass (β = 0.792, p = 0.015) were the variables that were significantly associated with irisin concentrations (R2 = 0.684, p < 0.001) after adjusting for confounding factors (age and HOMA-IR). Conclusions: These results suggest that serum irisin levels are related to visceral adiposity in non-diabetic HD patients.


Renal Failure | 2015

Association of ambulatory arterial stiffness index with sEPCR in newly diagnosed hypertensive patients

Hakki Yilmaz; Muzaffer Cakmak; Osman Inan; Tahir Darcin; Aynur Aktas; Özgül Malçok Gürel; Mukadder Ayse Bilgic; Nuket Bavbek; Ali Akcay

Abstract Aim: Increased arterial stiffness is strongly associated with cardiovascular diseases, while thrombotic events are more common than hemorrhagic events in hypertensive patients. Markers of a hypercoagulable state may also predict future cardiovascular events in hypertensive patients. Here, we speculated that increased arterial stiffness might lead to the development of a hypercoagulable state that can play a role in the thrombotic complications of hypertension. Soluble endothelial protein C receptor (sEPCR) is one such marker of hypercoagulation. The ambulatory arterial stiffness index (AASI) could be accepted as a non-invasive measure of arterial stiffness. The aim of this study was to investigate association of AASI with levels of sEPCR in newly diagnosed hypertensive patients. Materials and methods: The study included 263 newly diagnosed essential hypertensive patients and 55 healthy normotensive controls. All subjects underwent 24 h ambulatory blood pressure monitoring (ABPM); the AASI was derived from ABPM tracings. Plasma sEPCR was measured by ELISA. Results: Hypertensive patients (n = 263) had higher AASI, C-reactive protein (CRP) and sEPCR versus the normotensive healthy group (n = 55). Univariate analysis showed that AASI was positively associated with age (r = 0.212, p <  0.001) body mass index (r = 0.412, p < 0.001), pulse pressure (r = 0.350, p < 0.001), plasma sEPCR (r = 0.894, p < 0.001), 24-h heart rate (r = 0.176, p = 0.001) and inversely related to high-density lipoprotein (HDL) (r = −0.293, p < 0.001). Multivariate analyses revealed that sEPCR and HDL are independently correlated to AASI. Conclusion: We suggest that increased AASI is associated with elevated sEPCR. It might be responsible for subsequent thrombotic events in newly diagnosed hypertensive patients.


Case Reports in Medicine | 2012

Metastatic Prostate Adenocarcinoma Presenting Central Diabetes Insipidus

Hakki Yilmaz; Mustafa Kaya; Mücteba Can; Mustafa Özbek; Bahir Keyik

The pituitary gland and infundibulum can be involved in a variety of medical conditions, including infiltrative diseases, fungal infections, tuberculosis, and primary and metastatic tumors. Metastases to the pituitary gland are absolutely rare, and they are generally secondary to pulmonary carcinoma in men and breast carcinoma in women. Pituitary metastases more commonly affect the posterior lobe and the infundibulum than the anterior lobe. The posterior lobe involvement may explain why patients with pituitary metastases frequently present with diabetes insipidus. We are presenting a case report of a 78-year-old male patient who had metastatic prostate with sudden onset of polyuria and persistent thirst. He had no electrolyte imbalance except mild hypernatremia. The MRI scan of the brain yielded a suspicious area in pituitary gland. A pituitary stalk metastasis was found on magnetic resonance imaging (MRI) of pituitary. Water deprivation test was compatible with DI. A clinical response to nasal vasopressin was achieved and laboratory results revealed central diabetes insipidus. As a result, the intrasellar and suprasellar masses decreased in size, and urinary output accordingly decreased.

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