Browsing by Author "Uyar, Mehtap Erkmen"

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Differential Influence of Vitamin D Analogs on Left Ventricular Mass Index in Maintenance Hemodialysis Patients
(2014) Sezer, Siren; Tutal, Emre; Bal, Zeynep; Uyar, Mehtap Erkmen; Bal, Ugur; Cakir, Ulkem; Acar, Nurhan Ozdemir; Haberal, Mehmet; https://orcid.org/0000-0002-7326-8388; https://orcid.org/0000-0002-9446-2518; https://orcid.org/0000-0002-3462-7632; 24619898; JYQ-2550-2024; AAZ-5795-2021; AAK-4322-2021; AAJ-8097-2021
Purpose: Secondary hyperparathyroidism (SHPT) is a common feature in maintenance hemodialysis (MHD) patients. Inadequate treatment of SHPT has been associated with cardiovascular complications, and vitamin D therapy might influence the development of cardiovascular diseases. In the present study, we aimed to evaluate the effects of intravenous paricalcitol and calcitriol treatments on left ventricular mass index changes in MHD patients. Methods: We conducted an observational study with a 12-month follow-up duration to compare the outcomes of intravenous paricalcitol and calcitriol treatments in MHD patients. Eighty patients with moderate to severe SHPT were enrolled in the study. All the patients had normalized total serum Ca concentration <10.5 mg/dL, serum calcium-phosphorus product (Ca x P) <75, and parathyroid hormone level (PTH) level >= 300 pg/mL at the begining of the follow-up period. Results: The patients were divided into a paricalcitol group (n = 40) and a calcitriol group (n = 40). The demographic, clinical, and biochemical characteristics of the patients were similar at baseline. We observed significantly superior control of SHPT; lesser frequency of hypercalcemia and hyperphosphatemia, and Ca x P level elevations; and interruption of vitamin D treatment in the paricalcitol group. Moreover, we found no significant change in left ventricular mass index in the paricalcitol group, but found a significantly increased left ventricular mass index in the calcitriol group during the follow-up period (from 136.6 +/- 35.2 g/m(2) to 132.9 +/- 40.4 g/m(2) vs. from 137.2 +/- 30.1 g/m(2) to 149.4 +/- 31.0 g/m(2); p<0.044). Conclusion: We observed that, compared with calcitriol therapy, paricalcitol therapy reduced the PTH concentrations more effectively without causing hypercalcemia and hyperphosphatemia and might have a substantial beneficial effect on the development of left ventricular hypertrophy.
Hyperproteinuria As A Cardiovasculary Risk Factor in Renal Transplant Recipients
(2014) Guliyev, Orhan; Uyar, Mehtap Erkmen; Sezer, Siren; Bal, Zeynep; Colak, Turan; Demirci, Bahar Gurlek; Acar, Nurhan Ozdemir; Haberal, Mehmet; https://orcid.org/0000-0002-7326-8388; https://orcid.org/0000-0002-8372-7840; https://orcid.org/0000-0002-3462-7632; JYQ-2550-2024; AAZ-5795-2021; AAJ-8554-2021; AAJ-8097-2021
Hypoalbuminemia, Poor Calcium-Phosphorus Control and High Transporter Peritoneal Characteristics - Three Important 10-Year Survival Predictors for Peritoneal Dialysis Patients
(2014) Tutal, Emre; Bal, Zeynep; Sezer, Siren; Uyar, Mehtap Erkmen; 0000-0002-7326-8388; IAO-2608-2023; AAZ-5795-2021; JYQ-2550-2024
OBJECTIVE: Peritoneal transport characteristic is a potential survival predictor. In this study we evaluated the effect of transport characteristics on 10 year patient survival and compared its' impact with other possible survival predictors. MATERIAL and METHODS: We included 75 CAPD patients who were followed in our center for at least 10 years after initiation of PD. Based on the standard peritoneal equilibration test, PD patients were divided into two transporter groups: Low / Low average (n: 27) and High / High Average (n: 48). Clinical and demographic data were collected from patient charts and impact of transporter characteristics and some other well-known survival predictors were studied. RESULTS: 10 year PD survival rates were significantly lower in H/HA group (p: 0.001). Atherosclerosis-related mortality rate was significantly higher in H/HA group (45.9% vs. 7.6%, p: 0.043). Hypoalbuminemia, increased CaxP, chronic inflammation, H/HA transport status were independent predictors of PD and patient survival. Further analysis revealed that hypoalbuminemia (p: 0.0001) and increased CaxP levels (p: 0.0001) were the main predictors. CONCLUSION: This study suggests that peritoneal transport status is an important survival predictor. However keeping the calcium and phosphorus levels in recommended ranges, and improving nutritional status still have more importance for lowering mortality rates of PD patients.
Iloprost as an acute kidney injury-triggering agent in severely atherosclerotic patients
(2016) Uyar, Mehtap Erkmen; Yucel, Piril; Ilin, Sena; Bal, Zeynep; Yildirim, Saliha; Uyar, Ahmet Senol; Akay, Tankut; Tutal, Emre; Sezer, Siren; 27841898; AAZ-5795-2021
Background: Iloprost, a stable prostacyclin analog, is used as a rescue therapy for severe peripheral arterial disease (PAD). It has systemic vasodilatory and anti-aggregant effects, with severe vasodilatation potentially causing organ ischaemia when severe atherosclerosis is the underlying cause. In this study, we retrospectively analysed renal outcomes after iloprost infusion therapy in 86 patients. Methods: Eighty-six patients with PAD who received iloprost infusion therapy were retrospectively analysed. Clinical and biochemical parameters were recorded before (initial, Cr1), during (third day, Cr2), and after (14th day following the termination of infusion therapy, Cr3) treatment. Acute kidney injury (AKI) was defined according to KDIGO guidelines as a >= 0.3 mg/dl (26.52 mu mol/l) increase in creatinine levels from baseline within 48 hours. Results: Cr2 (1.46 +/- 0.1 mg/dl) (129.06 +/- 8.84 mu mol/l) and Cr3 (1.53 +/- 0.12 mg/dl) (135.25 +/- 10.61 mu mol/l) creatinine levels were significantly higher compared to the initial value (1.15 +/- 0.6 mg/dl) (101.66 +/- 53.04 mu mol/l). AKI was observed in 36 patients (41.86%) on the third day of iloprost infusion. Logistic regression analysis revealed smoking and not using acetylsalicylic acid as primary predictors (p = 0.02 and p = 0.008, respectively) of AKI during iloprost treatment. On the third infusion day, patients' urinary output significantly increased (1813.30 +/- 1123.46 vs 1545.17 +/- 873.00 cm(3)) and diastolic blood pressure significantly decreased (70.07 +/- 15.50 vs 74.14 +/- 9.42 mmHg) from their initial values. Conclusion: While iloprost treatment is effective in patients with PAD who are not suitable for surgery, severe systemic vasodilatation can cause renal ischaemia, resulting in non-oliguric AKI. Smoking, no acetylsalicylic acid use, and lower diastolic blood pressure are the clinical risk factors for AKI during iloprost treatment.
Long-Term Oral Nutrition Supplementation Improves Outcomes in Malnourished Patients With Chronic Kidney Disease on Hemodialysis
(2014) Sezer, Siren; Bal, Zeynep; Tutal, Emre; Uyar, Mehtap Erkmen; Acar, Nurhan Ozdemir; 24436491
Background: There is no consensus on the type, time of initiation, or duration of use of enteral nutrition in patients with chronic kidney disease (CKD). This study aimed to compare the effects of a renal-specific oral nutrition supplement (RS-ONS) and a standard recommended nutrition regime on biochemical and nutrition markers in malnourished patients with CKD on hemodialysis. Methods: Sixty-two malnourished patients with CKD, divided into experimental (RS-ONS; n = 32; mean [SD] age, 62.0 [11.3] years; 55.2% female) and control (CON; n = 30; mean [SD] age, 57.2 [12.3] years; 31% female) groups, were evaluated for anthropometric, biochemical, and inflammatory parameters. Results: Mean (SD) serum albumin levels were significantly increased in the RS-ONS group from 3.5 (0.3) g/dL at baseline to 3.7 (0.2) g/dL at 6 months (P = .028). Significantly fewer patients had serum albumin levels of <3.5 g/dL after month 6. Dry weight of patients significantly increased in the RS-ONS but decreased in the CON groups (P < .001 for each). Percent change from baseline revealed negative results for bioelectrical impedance analysis (P < .001) in the CON group. Malnutrition inflammation score at 6 months (P = .006) and erythropoietin (EPO) dose requirements were higher in the CON group (P = .012). Conclusions: Our findings indicate that consuming RS-ONS improves serum albumin and anthropometric measures, as well as reduces EPO dose, in patients with CKD.
Low 25-Hydroxy Vitamin D, High Fibroblast Growth Factor 23 and Arterial Stiffness in Hemodialysis Patients with Chronic Kidney Disease: "The Chicken or Egg Phenomenon"
(2014) Bal, Zeynep; Uyar, Mehtap Erkmen; Gokustun, Dilek; Demirci, Bahar Gurlek; Tutal, Emre; Sezer, Siren; https://orcid.org/0000-0002-7326-8388; AAZ-5795-2021; JYQ-2550-2024
New-Onset Diabetes and Glucose Regulation Are Significant Determinants of Left Ventricular Hypertrophy in Renal Transplant Recipients
(2015) Sezer, Siren; Uyar, Mehtap Erkmen; Tutal, Emre; Bal, Zeynep; Guliyev, Orhan; Colak, Turan; Hasdemir, Efe; Haberal, Mehmet; 25945353
Background. New-onset diabetes after transplantation (NODAT) is associated with decreased graft survival and an increased risk for cardiovascular disease. The objective of this study was to evaluate the risk factors for development of NODAT and its' relationship with arterial stiffness and left ventricular mass index (LVMI) in kidney transplant recipients. Methods. 159 kidney transplant recipients were selected from our transplantation center who underwent renal transplantation between years 2007 and 2010. Results. Among 159 patients, 57 (32.2%) patients were with NODAT who were significantly older than patients without diabetes (P: 0.0001). Patients with NODAT had significantly higher pulse wave velocity (PWv) (P: 0.033) and left ventricular mass index LVMI (P: 0.001) compared to patients without NODAT. Further analysis was done according to LVMI as follows: LVMI > 130 g/m(2) (n: 57) and LVMI <= 130 g/m(2) (n: 102). We observed higher office systolic and diastolic BP, serum trygliceride, glucose, creatinine, age, and HbA1c (P: 0.0001) levels in patients with LVMI > 130 g/m(2). Linear regression analysis revealed that HbA1c was the major determinant of LVMI (P: 0.026, beta: 0.361). Conclusions. HbA1c is the major determinant of LVMI, so strict control of serum glucose levels is essential for preventing cardiovascular disease in patients with NODAT.
Oxidative Stress in Maintenance Hemodialysis Patients
(2014) Uyar, Mehtap Erkmen; Bal, Zeynep; Bayraktar, Nilufer; Demirci, Bahar Gurlek; Sayin, Burak; Sezer, Siren; https://orcid.org/0000-0002-7886-3688; https://orcid.org/0000-0001-8287-6572; https://orcid.org/0000-0002-7326-8388; IAO-2608-2023; AAZ-5795-2021; Y-8758-2018; J-3707-2015; JYQ-2550-2024
Posttransplant Hyperuricemia As A Cardiovascular Risk Factor: Correlation Between Cardiovascular Risk Factors
(2016) Sezer, Siren; Tutal, Emre; Bal, Zeynep; Uyar, Mehtap Erkmen; Haberal, Mehmet; https://orcid.org/0000-0002-3462-7632; AAZ-5795-2021; IAO-2608-2023; AAJ-8097-2021
Prolongation of Corrected QT Interval Is a Strong Predictor of Arterial Stiffness in Maintenance Hemodialysis Patients: A Prospective Observational Study
(2017) Bal, Ugur; Bal, Zeynep; Karakose, Suleyman; Tutal, Emre; Uyar, Mehtap Erkmen; Sezer, Siren; 0000-0003-2026-2764; 0000-0002-9446-2518; P-4553-2018; AAK-4322-2021; AAZ-5795-2021
Background: Rate of mortality due to cardiovascular diseases is high in Maintenance Hemodialysis (MHD) patients. Additionally, prolonged QT interval is reportedly associated with high-risk ventricular arrhythmia and sudden death. Vascular calcification may be related to QT dispersion interval in MHD patients because the extensive nature of the calcification process may involve the conducting system and myocardium. Objectives: This study aimed to evaluate the relationship between QT interval and Pulse Wave Velocity (PWV) as a sign of arterial stiffness associated with atherosclerosis in MHD patients. Patients and Methods: This prospective, observational study was conducted on 149 eligible MHD patients for 12 months. Patients using drugs known to affect QT interval were excluded. The patients were divided into four groups as follows: normal corrected QT (QTc) interval at the beginning and end of the study (n = 44, 29.5%), normal QTc interval at the beginning but prolonged QTc interval at the end of the study (n = 30, 20.1%), prolonged QTc interval at the beginning but normal QTc interval at the end of the study (n = 24, 16.1%), and prolonged QTc interval at the beginning and end of the study (n = 51, 34.2%). Demographic parameters, laboratory parameters, and PWV were assessed at the beginning and the 12th month of the study. Then, the data were analyzed using ANOVA or Pearson 2 test and P < 0.05 was considered to be statistically significant. Results: The study groups were similar with respect to age and comorbidities, including diabetes mellitus, hypertension, and dyslipidemia. In addition, there were no significant differences among the groups regarding the initial PWV (P = 0.412); however, the ending PWV showed significant differences (P = 0.029). The results of multivariate analysis showed that PWV was independently associated with change in the maximum QTc (confidence interval: 0.039 -1.787, P = 0.031, beta= 0.178). Conclusions: The results suggested inclusion of QTc interval prolongation, as a predictor of cardiovascular disease, either alone or in combination with PWV in such high-risk patients.
Relationship Between Proteinuria and Pulsewave Velocity in Patients with Stage 1-4 Chronic Kidney Disease
(2014) Uyar, Mehtap Erkmen; Tutal, Emre; Bal, Zeynep; Guliyev, Orhan; Sezer, Siren; https://orcid.org/0000-0002-7326-8388; IAO-2608-2023; AAZ-5795-2021; JYQ-2550-2024
The Role of Oxidative Stress and Inflammatory Response in High-Fat Diet Induced Peripheral Neuropathy
(2014) Ozay, Rafet; Uzar, Ertugrul; Aktas, Abit; Uyar, Mehtap Erkmen; Gurer, Bora; Evliyaoglu, Osman; Cetinalp, Nuri Eralp; Turkay, Cansel; 24407112
Objective: Earlier studies suggest that high-calorie diet is an important risk factor for neuronal damage resulting from oxidative stress of lipid metabolism. In our experimental study of rats under high-fat diet, oxidative stress markers and axonal degeneration parameters were used to observe the sciatic nerve neuropathy. The aim of this study is to evaluate the pathophysiology of neuropathy induced by high-fat diet. Methods: A total of 14 male rats (Wistar albino) were randomly divided into two experimental groups as follows; control group (n = 7) and the model group (n = 7); while control group was fed with standard diet; where the model group was fed with a high-fat diet for 12 weeks. At the end of 12 weeks, the lipid profile and blood glucose levels, interleukin-1 beta (IL-1), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), and transforming growth factor-beta (TGF-beta) levels were studied. Tissue malondialdehyde (MDA), nitric oxide (NO) levels and super-oxide dismutase (SOD), paraoxonase-1 (PON-1) and glutathione peroxidase (GPx) activities were studied. The distal blocks of the left sciatic nerves were evaluated for histomorphological analysis (including mean axon area, axon numbers, nerve fiber diameters, axon diameters, and thickness of myelin sheets). Results: Body weights, serum glucose and high-density lipoprotein (HDL) levels of rats were found not statistically significantly different compared between the model and the control groups (p > 0.05). Serum cholesterol, triglyceride, TGF-beta and TNF-alpha levels were significantly higher in the model group when compared with the control group (p < 0.05). IL-1 and IL-6 levels were not statistically significantly different compared between the model group and the control group (p > 0.05). The MDA and NO levels and the SOD and GPx activities of the sciatic nerves in model group were statistically significantly higher than the control group (p < 0.05). In addition, the activities of PON-1 were statistically significantly lower in the model group when compared with the control group (p < 0.05). The difference in the total number of myelinated axons between the control group and the model group was not statistically significant (p > 0.05). The nerve fiber diameter and the thickness of the myelin sheet were statistically significantly lower in the model group when compared with the control group (p < 0.05). The axon diameter and area were significantly decreased in the model group when compared with the control group (p < 0.05). Conclusion: Our results support that dyslipidemia is an independent risk factor for the development of neuropathy. In addition, we postulated that oxidative stress and inflammatory response may play an important role in the pathogenesis of high-fat diet induced neuropathy. (C) 2014 Elsevier B.V. All rights reserved.
Sevelamer Decreases Serum Uric Acid Levels and Improves Arterial Stiffness in Hemodialysis Patients
(2014) Sezer, Siren; Demirci, Bahar Gurlek; Tutal, Emre; Bal, Zeynep; Uyar, Mehtap Erkmen; Acar, Fatma Nurhan Ozdemir; https://orcid.org/0000-0002-7326-8388; https://orcid.org/0000-0002-5682-0943; JYQ-2550-2024; AAZ-5795-2021; AAK-1697-2021
Sevelamer Decreases Serum Urıc Acıd Levels and Improves Arterıal Stıffness in Hemodıalysıs Patıents
(2015) Sezer, Siren; Demirci, Bahar Gurlek; Tutal, Emre; Bal, Zeynep; Uyar, Mehtap Erkmen; Acar, Fatma NurhanOzdemir; 0000-0002-5682-0943; IAO-2608-2023; AAZ-5795-2021; AAK-1697-2021