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Dive into the research topics where Nihal Ozkayar is active.

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Featured researches published by Nihal Ozkayar.


The American Journal of Gastroenterology | 2006

Is Congenital Hepatic Fibrosis a Pure Liver Disease

Ozlem Yonem; Nihal Ozkayar; Ferhun Balkanci; Ozgur Harmanci; Cenk Sokmensuer; Osman Ersoy; Yusuf Bayraktar

OBJECTIVES:An association between congenital hepatic fibrosis (CHF) and several different conditions is being increasingly recognized. We aimed to investigate, prospectively, these associated disorders and the clinical consequences for patients with CHF.MATERIALS AND METHODS:CHF was diagnosed using liver biopsy, abdominal ultrasound (US), Doppler US, upper endoscopy, and abdominal computed tomography (CT) in 19 patients (13 women, 6 men). CT portography and splenoportography with digital subtraction angiography were performed if indicated. Endoscopic retrograde cholangiopancreatography (ERCP) was performed to investigate the extent of portal vein involvement of the common bile duct if it existed, to remove a stone located in the common bile duct when documented, and to confirm the diagnosis of Carolis syndrome. Cranial MRI was done when clinical findings suggested brain involvement.RESULTS:The mean age of the patients was 29.47 ± 12.06, ranging from 13 to 57. CHF-associated diseases were Carolis syndrome, polycystic kidney disease, cavernous transformation of the portal vein, Jouberts syndrome, von Meyenburg complex, polydactyly, medullary sponge kidney, and pancreatic duct atrophy. In two cases, cholangiocarcinoma had developed. There was only one case with pure CHF. Portosystemic shunt, TIPS, or splenectomy were performed in some cases to control bleeding from esophageal varices. Papillotomy and stone extraction from the common bile duct were performed in four patients with Carolis syndrome complicated by cholangitis. Three patients died of complications of CHF. Two patients with Carolis syndrome underwent liver transplantation.CONCLUSION:In this prospective study, it seems that CHF is not a pure liver disease but rather a multiorgan disorder involving the brain, portal vein, kidneys, and bile ducts. In most cases, the clinical picture includes other organ involvement, rather than purely the liver parenchyma.


Journal of The American Society of Hypertension | 2016

Dynamic thiol/disulphide homeostasis in patients with newly diagnosed primary hypertension

Ihsan Ates; Nihal Ozkayar; Bayram Inan; Fatma Meric Yilmaz; Canan Topcuoglu; Salim Neselioglu; Ozcan Erel; Fatih Dede; Nisbet Yilmaz

We aimed to investigate the thiol/disulphide homeostasis in patients with newly diagnosed primary hypertension with a novel and automated method. Blood thiol/disulphide homeostasis, which consists of native thiol/disulphide exchanges, was investigated in 45 patients with primary hypertension and 45 healthy controls. The levels of native thiol, total thiol, and native thiol/total thiol ratio were lower while the disulphide level and disulphide/native thiol and disulphide/total thiol ratios were higher in patients with primary hypertension when compared with those in the control group. Positive correlation was detected between 24-hour systolic and diastolic blood pressure levels and disulphide/native thiol ratio. With reference to the stepwise multiple linear regression model; increase in disulphide/native thiol ratio and log(24-hour urine microalbumin) and decrease in native thiol/total thiol ratio are independent predictors of 24-hour systolic and diastolic blood pressure. This study demonstrated that thiol/disulphide homeostasis was shifted toward disulphide formation in patients with primary hypertension.


Korean Journal of Laboratory Medicine | 2015

Association Between High Platelet Indices and Proteinuria in Patients With Hypertension

Ihsan Ates; Mesudiye Bulut; Nihal Ozkayar; Fatih Dede

Background We aimed to determine the association between platelet indices including plateletcrit (PCT), mean platelet volume (MPV), platelet distribution width (PDW), and proteinuria associated with hypertension (HT) as well as the relative power of each to predict proteinuria. Methods The study included 223 patients (68 men and 155 women) with primary HT. PCT, MPV, PDW, and proteinuria levels were measured. The patients were divided into two groups according to proteinuria status based on 24-hr urinary protein excretion: proteinuria (+) group (15 men and 40 women) and proteinuria (-) group (53 men and 115 women). Results The mean and SD of platelet count, PDW, PCT, and MPV were 278.8±49.6×109/L, 13.5±1.8%, 0.31±0.07%, and 11.3±2.6 fL, respectively. The mean platelet count, PCT, MPV, and PDW were significantly higher in the proteinuria (+) group than in the proteinuria (-) group (P<0.05); there were no significant differences in the other blood parameters between the two groups. The platelet count, PCT, MPV, and PDW were independent risk factors predictive of proteinuria according to a stepwise regression analysis of PDW, PCT, and MPV. PCT was the strongest independent predictor of proteinuria. Conclusions The platelet indices PCT, PDW, and MPV were significantly higher in patients with proteinuria than in those without it. Among these three indices, PCT was the strongest predictor of proteinuria.


Scandinavian Cardiovascular Journal | 2015

Relationship between oxidative stress parameters and asymptomatic organ damage in hypertensive patients without diabetes mellitus

Ihsan Ates; Nihal Ozkayar; Canan Topcuoglu; Fatih Dede

Abstract Objective. We aimed to evaluate the levels of oxidative stress (OS) parameters such as total antioxidant status or TAS, total oxidant status (TOS), OS index (OSI), paraoxonase 1 (PON1), arylesterase, and total thiol in hypertensive patients with and without asymptomatic organ damage (AOD), and to determine the relationship between these parameters and AOD. Design. Sixty-six patients (21 men, 45 women) with AOD and 66 patients without AOD (21 men, 45 women) were enrolled in the study. Serum OS parameters were measured by colorimetric method. Results. The OSI levels were found to be higher while PON1, PON1/high-density lipoprotein, and arylesterase levels were found to be lower in patients with AOD compared with those in the patients without AOD. Stepwise regression analysis showed high 24-h mean systolic blood pressure, OSI, and low arylesterase level to be independent predictors of AOD. Conclusion. OS level was found to be higher in hypertensive patients with AOD compared with the patients without AOD. However, it is not clear whether increased OS leads to AOD or AOD increases the level of OS. For this purpose, OS level needs to be decreased by antioxidant therapies and patients need to be followed up for a longer duration.


Nefrologia | 2015

Relation between serum cathepsin D levels and endothelial dysfunction in patients with chronic kidney disease.

Nihal Ozkayar; Serhan Piskinpasa; Fatma Akyel; Didem Turgut; Mesudiye Bulut; Turan Turhan; Fatih Dede

We aimed to investigate the role of cathepsin D, an inflammatory and atherosclerotic mediator, in endothelial dysfunction in chronic kidney disease. The study included 65 patients with stage 2–4 chronic kidney disease (35 females, 30 males; mean age, 55.8±15.6 years). Serum creatinine and cathepsin D levels and glomerular filtration rates (GFRs) were determined, and brachial flow-mediated dilation (FMD) percentage was measured by two-dimensional gray scale and color flow Doppler and vascular imaging. FMD ≤6% was considered to indicate endothelial dysfunction. Mean GFR, median creatinine levels, and median cathepsin D levels were 40.2±11.2mL/min/1.73m2, 1.7mg/dL, and 819.75ng/mL, respectively. Endothelial dysfunction was present in 30 of the 65 patients (46.2%). There was a significant difference between groups with and without endothelial dysfunction in terms of cathepsin D (p=0.001) and creatinine (p=0.03) levels, and negative and significant correlations were found between brachial artery FMD% and cathepsin D (r=−0.359, p=0.003) and creatinine (r=−0.304, p=0.014) levels. Cathepsin D, which is known to be associated with atherosclerosis, may play a role in the process of endothelial dysfunction. Further studies are essential to determine the exact function of cathepsin D in endothelial dysfunction in chronic kidney disease and to determine its value as a tool for early diagnosis and target for treatment of cardiovascular diseases in patients with chronic kidney disease.


Clinical and Experimental Hypertension | 2014

Blood pressure measurements, blood pressure variability and endothelial function in renal transplant recipients.

Nihal Ozkayar; Bulent Altun; Tolga Yildirim; Rahmi Yilmaz; Fatih Dede; Gunes Arik; Ercan Turkmen; Mutlu Hayran; Fazil Tuncay Aki; Mustafa Arici; Yunus Erdem

Abstract Background/Aims: Hypertension is an important cardiovascular risk factor in renal transplant recipients. Elevated blood pressure variability (BPV) during 24-h ambulatory blood pressure monitoring (ABPM) is associated with increased risk of target organ damage and cardiovascular events, independent of mean blood pressure levels. We aimed to evaluate the relationship between endothelial function, blood pressure levels obtained by various measurement methods, and BPV in renal transplant recipients. Methods: In total, 73 hypertensive renal transplant recipients were included in the study. Office blood pressure measurements, central blood pressure measurements, home blood pressure measurements and 24-h ABPM were obtained from the subjects. BPV was calculated using the average real variability index. All patients underwent brachial flow-mediated vasodilatation tests. Predictive values of blood pressures obtained by different measurement techniques and BPV on endothelial functions were investigated. Results: Endothelial dysfunction was present in 68.5% of the patients. No difference was found between the group with and without endothelial dysfunction with regard to office systolic or diastolic blood pressure, central blood pressure or home systolic blood pressure. In the group with endothelial dysfunction, 24-h ambulatory systolic blood pressure and night-time ambulatory systolic blood pressure were higher. In patients with endothelial dysfunction, the 24-h systolic, diastolic and mean BPV were all higher. There was also a negative correlation between the percentage of flow-mediated vasodilatation with 24-h mean and systolic BPV. Conclusion: Patients with endothelial dysfunction had significantly higher ambulatory blood pressure values and higher BPV. There was a significant negative correlation between endothelial function and BPV.


Nephro-urology monthly | 2014

Evaluation of sarcopenia in renal transplant recipients.

Nihal Ozkayar; Bulent Altun; Meltem Halil; Mehmet Emin Kuyumcu; Gunes Arik; Yusuf Yesil; Tolga Yildirim; Rahmi Yilmaz; Servet Ariogul; Cetin Turgan

Background: Chronic kidney disease can lead to sarcopenia; however, no study has described sarcopenia in the patients undergoing renal transplantation. Objectives: The aim of the present study was to assess the prevalence of sarcopenia in renal transplant recipients (RTR) and to evaluate the demographic and metabolic risk factors associated with sarcopenia in these patients. Patients and Methods: Sarcopenia was diagnosed by measuring handgrip strength in 166 RTR (68 females and 98 males; mean age, 37.9 ± 11.9 years). Basal metabolic rate, fat mass, free-fat mass, total body water, body mass index, and calf circumference were determined, along with blood biochemistry, vitamin D levels, and glomerular filtration rate. Results: Among 166 patients, sarcopenia was present in 34 (20.5%). Handgrip, basal metabolic rate, free fat mass, and total body water were significantly lower in patients with sarcopenia in comparison with those without sarcopenia. There were no differences between patients with and without sarcopenia in terms of mean time since transplantation, the presence of diabetes mellitus, hypertension, coronary artery disease, hyperlipidemia, glomerular filtration rate, and body mass index. Univariate analysis revealed significant differences between patients with and without sarcopenia with respect to age (mean of 43.70 ± 13.97 and 36.37 ± 10.82 years, respectively; P = 0.007) and 25-OH vitamin D levels (median (IQR) of 12 (2-39) and 17.70 (3-68) μg/L, respectively; P = 0.024). There was a statistically significant positive correlation between vitamin D levels and handgrip strength (r = 0.334; P < 0.001). Multivariate regression analysis determined that age was an independent predictive variable of sarcopenia in RTR (β = 1.060; 95% CI, 1.017-1.105; and P = 0.006). Conclusions: Chronic renal disease contributes to sarcopenia, which may develop at an earlier age in RTR.


Blood Coagulation & Fibrinolysis | 2005

No alteration in the Pfa-100 in vitro bleeding time induced by the Ginkgo biloba special extract, Egb 761, in elderly patients with mild cognitive impairment

Meltem Halil; Mustafa Cankurtaran; Burcu Balam Yavuz; Nihal Ozkayar; Zekeriya Ulger; Didem S. Dede; Ali Shorbagi; Yahya Buyukasik; Ibrahim C. Haznedaroglu; Servet Arogul

EGb 761 is widely used in the management of mild cognitive impairment in the elderly population. Elucidation of the effects of EGb 761 on primary haemostasis via PFA-100 could represent an important step for better understanding of the haemostatic safety of EGb 761. The purpose of this prospective study is to assess the effects of Ginkgo biloba special extract, EGb 761, on PFA-100 in vitro bleeding time in elderly patients with mild cognitive impairment. A total of 40 elderly patients aged 65–79 years who were referred for geriatric assessment and who were diagnosed as having mild cognitive impairment were included. Patients were started on 80 mg EGb-761 three times daily. The complete set of PFA-100 in vitro bleeding time and coagulation parameters including prothrombin time, activated partial thromboplastin time and International Normalized Ratio were assessed before and on the seventh day of treatment with EGb 761. There was no statistically significant prolongation in PFA-100 in vitro bleeding time or coagulation parameters in patients receiving EGb 761 after 7 days. The data about the safety of EGb 761 from the point of primary haemostasis in our elderly patient population with mild cognitive impairment casts hope for the future management of this ‘difficult-to-treat’ population with the promising Ginkgo extracts.


Hypertension Research | 2016

Elevated circulating sST2 associated with subclinical atherosclerosis in newly diagnosed primary hypertension

Ihsan Ates; Nihal Ozkayar; Hale Ates; Uğur Nadir Karakulak; Oğuzhan Kursun; Canan Topcuoglu; Bayram Inan; Nisbet Yilmaz

The aims of this study were to measure the levels of interleukin-33 (IL-33) and soluble Suppression of Tumorigenicity 2 (sST2) in patients with newly diagnosed primary hypertension (HT) and to determine the relationship between carotid intima-media thickness (CIMT) and IL-33/sST2. Eighty-two patients with newly diagnosed primary HT and ninety healthy volunteers were included in the study. CIMT ⩾0.9 mm was considered as significant for subclinical atherosclerosis. The sST2 levels of patients with primary HT were higher than those of the control group, whereas the IL-33 levels of these patients were much lower than those of the control group. The sST2 levels were higher in patients with subclinical atherosclerosis than in control subjects or patients with primary HT but not with subclinical atherosclerosis. In the primary HT group, sST2 had a positive correlation with CIMT, 24-h systolic–diastolic blood pressure, low-density lipoprotein and C-reactive protein, whereas sST2 had a negative correlation with the IL-33 level. A stepwise multivariable logistic regression analysis revealed that sST2 is an independent risk factor for subclinical atherosclerosis. Although the diagnostic predictive value of HT risk was determined as >51.8 pg l−1 in the receiver operating characteristic curve analysis in respect of the sST2 level, the diagnostic predictive value for subclinical atherosclerosis risk was determined to be >107.2 pg l−1. The sST2 level displays a positive correlation with atherosclerotic changes, and is an independent risk factor for subclinical atherosclerosis expressed as increased CIMT.


Medical Science Monitor | 2015

Relationship between socioeconomic level, and the prevalence of masked hypertension and asymptomatic organ damage.

Ihsan Ates; Mustafa Altay; Mustafa Kaplan; Nihal Ozkayar; Guvenc Toprak; M. Erdem Alagüney; Adem Özkara

Background This study aimed to determine the prevalence of masked hypertension (MHT) and its association with asymptomatic organ damage (AOD) in a low socioeconomic district of Ankara, Turkey. Material/Methods We retrospectively reviewed data obtained from the medical records of 712 patients with no known diagnosis of hypertension who presented to a polyclinic due to symptoms related to elevated blood pressure (BP) and were screened for MHT. Essential hypertension (EHT) existed in 86 patients screened for AOD. The presence of AOD in patients diagnosed with MHT and EHT was recorded. Results Among the 712 patients, 206 were diagnosed with EHT. Among the remaining 506 patients, 73 were diagnosed with MHT. The patients with MHT had significantly higher left ventricular mass index, carotid intima-media thickness, and 24-h urinary microalbuminuria level (all indicators of AOD) than those with EHT. Conclusions A significantly higher percentage of patients with MHT had AOD, as compared to those with EHT, in a low socioeconomic district of Ankara. Based on this finding, patients who present with hypertensive symptoms but have a normal BP should be advised to measure their BP at home.

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