Browsing by Author "Guvenc Y."

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    Endothelial dysfunction in preeclampsia: Increased homocysteine and decreased nitric oxide levels
    (2003) Var A.; Yildirim Y.; Onur E.; Kuscu N.K.; Uyanik B.S.; Goktalay K.; Guvenc Y.
    Endothelial dysfunction underlies the pathogenesis of preeclampsia, but its mechanism has not yet been completely understood. Elevated oxygen free radicals may partially explain the endothelial cell damage. In this study, we have aimed to measure homocysteine (Hcy) and nitric oxide (NO) levels as endothelial dysfunction markers in preeclamptic women. Nineteen preeclamptic (33.9 ± 1.4 weeks) and 15 gestational-age-matched normal pregnant women (35.5 ± 0.7 weeks) were included in the study. Mean NO level was significantly lower (p < 0.001) and mean Hcy level was significantly higher (p < 0.001) in the preeclamptic group. Elevated Hcy and oxygen free radical levels could decrease NO levels due to the reaction with each other and reduced NO may increase blood pressure and ischemia in preeclamptic patients. We have concluded that increased Hcy and oxygen free radical levels, and decreased NO levels are closely associated with preeclampsia-related endothelial dysfunction. Copyright © 2003 S. Karger AG, Basel.
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    Biochemical changes representing oxidative stress on brain tissue due to intraabdominal hypertension in a rat model
    (2007) Karabekir H.S.; Guzey F.K.; Balci C.; Guvenc Y.; Onur E.; Akbulut G.; Serteser M.
    Introduction: Intraabdominal hypertension affects the central nervous system in addition to respiratory, renal and cardiovascular systems. This effect that, investigated in detail by clinical and experimental studies, is due to the increase of intracranial pressure and decrease of cerebral perfusion pressure caused by the increase of intrathoracic pressure and increase of pressure of great veins. However, no study has been found on biochemical changes on central nervous tissue due to intraabdomial hypertension. Material and methods: Thirty rats were divided into three groups containing 10 animals: sham group, study group I and study group II. In group I, intraabdominal pressure was elevated to 20 mmHg, and in group II, it was elevated to 30 mmHg for 60 minutes. Intracranial pressures (ICP) in all animals were monitored. Values of biochemical parameters including thiobarbituric acid, nitrite oxide, xanthine oxidase, protein carbonyls and protein sulfhydryl in cortical, subcortical, cerebellar and spinal cord tissues were compared with the corresponding values in sham rats. Results: Thiobarbituric acid (0.58±0.8 and 0.76±0.04 vs. 0.23±0.03, p<0.05 and p<0.001), nitrite oxide (3.11±0.10 and 8.46±0.54 vs. 1.52±0.18, p<0.05 and p<0.001), xantine oxidase (1.55±0.11 and 3.01±0.25 vs. 0.32±0.09, p<0.001) and carbonyl levels (1.41±0.01 and 1.69±0.01 vs. 1.22±0.03, p<0.001) of the various central nervous system regions and ICP were increased. SH levels (92.60±2.50 and 74.60±3.80 vs. 139.20±4.72, p<0.001) were decreased after intraabdominal hypertension, and higher IAP generally caused more detrimental effects on these parameters. The levels of spinal cord and cerebellum samples were significantly worse in the study groups for most of the markers. Conclusions: Intraabdominal hypertension may cause biochemical changes representing oxidative stress on various regions of central nervous system even 60 minutes after increase of intraabdominal pressure, and higher IAH causes more detrimental effects. Most prominent effects were seen in spinal cord and cerebellar tissue suggesting that compression of lumbar vertebral venous pressure might have a role in addition to increase of ICP due to increase of pressure of great veins caused by increase of intrathoracic pressure. Copyright © 2007 Termedia & Banach.
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    Oxidative stress impairs endothelial nitric oxide levels in Behçets' disease
    (2011) Onur E.; Kabaroglu C.; Inanir I.; Var A.; Guvenc Y.; Gunay O.; Gunduz K.
    Background: Behçet's disease (BD) is an inflammatory vasculitis. Endogenous nitric oxide (NO), produced by endothelial cells, has pleiotropic effects such as vasodilatator, antiplatelet, antiproliferative. Reactive oxygen species (ROS) are produced at sites of endothelial inflammation. ROS target polyunsaturated lipids, which results in malondialdehyde (MDA) production. Objective: The aim was to investigate the oxidative stress in BD patients by measuring MDA and total antioxidant status (TAS) levels and to establish a possible relationship with respect to NO levels regarding disease activity. Materials and methods: 55 BD patients (30 active/25 inactive) and 20 healthy volunteers were included in the study. Blood samples were drawn following an overnight fasting. TAS and MDA levels were determined spectrophotometrically. Serum nitrite (NO 2-) and nitrate (NO 3-) levels were measured to estimate NO production. Data were expressed as mean ± SD. Results: TAS levels were significantly lower in BD patients than the controls (1.19 ± 0.34 vs. 3.29 ± 0.89 mmol/L). In the active BD group, MDA levels (0.36 ± 0.19 nmol/mL) were significantly higher than both the inactive BD group (0.25 ± 0.18 nmol/mL) and controls (0.18 ± 0.41 nmol/mL). NO levels were significantly lower in the active group compared to the inactive group (18.0 ± 2.80 vs. 19.40 ± 2.70 μmol/L). MDA levels correlated negatively with NO levels in the active group. Conclusion: Decreased NO levels mediated by increased oxidative stress significantly contribute to endothelial dysfunction observed in BD. © 2011 Informa Healthcare USA, Inc.
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    Mannose binding lectin (MBL) gene polymorphism and relationship between serum MBL concentrations in COPD patients; [KOAH hastalarında mannoz baǧlayan lektin (MBL) gen polimorfizmi ve serum MBL derişimi arasındaki ilişki]
    (Turkish Biochemistry Society, 2012) Ulutas G.S.; Taneli F.; Alpaydin A.O.; Cetinkaya C.; Ulman C.; Guvenc Y.; Dinc G.; Coskun A.S.
    Aim: We aimed to assess mannose-binding lectin (MBL) gene polymorphisms and serum MBL concentrations in a sample of Turkish chronic obstructive pulmonary disease (COPD) patients as well as in cigarette smokers. Furthermore, we looked for the possible correlations of serum MBL concentrations with pulmonary function tests. Materials and methods: Forty COPD patients and 40 healthy volunteers were included. The subjects were thereafter divided into 2 groups according to smoking status. Circulating MBL concentrations were assessed by ELISA and MBL gene polymorphisms were assessed by real time PCR method. Spirometry was performed to all subjects except healthy nonsmokers. Results: In the whole study population MBL gene frequencies were found 82.5%(66/80) for A/B genotype, 15%(12/80) for D/D genotype and 2.5%(2/80) for B/B genotype. Circulating MBL concentrations were found 2103±1311 ng/ml and 2324±1001 ng/ml in smoker and nonsmoker COPD patients, respectively, whereas they were 1746±1142 ng/ml in smoker and 2040±879 ng/ml in nonsmoker controls. No statistical difference was found between the study groups for serum MBL concentrations. Serum MBL concentration correlated positively with cigarette smoking (r=0.280, p=0.030) and negatively with pulmonary functions (FEV1 (r=- 0.246, p=0.058). Conclusion: To our knowledge, no previous study has been performed in healthy Turkish population to detect the MBL gene polymorphisms. A/B genotype was the most frequent MBL variant in our study population; however serum MBL concentrations were not found compatible with MBL deficiency. We believe these results need further investigation which includes larger series to evaluate whether serum MBL concentration is a risk factor for COPD. © TurkJBiochem.com.
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    Relationship of neutrophil gelatinase-associated lipocalin (NGAL) and procalcitonin levels with the presence and severity of the preeclampsia
    (Taylor and Francis Ltd., 2015) Artunc-Ulkumen B.; Guvenc Y.; Goker A.; Gozukara C.
    Objective: The aim of the present study was to evaluate changes in maternal serum neutrophil gelatinase-associated lipocalin (NGAL) and procalcitonin (PCT) concentrations in preeclampsia.Material and method: This case-control study consisted of 40 preeclamptic and 40 healthy singleton pregnancies matched for age and body mass index. Serum NGAL and PCT levels were compared between the groups. Diagnostic performance and clinical association of these markers were evaluated.Results: NGAL and PCT concentrations were significantly higher in preeclamptic group (p < 0.0001 and p = 0.001, respectively) and their levels were correlated with the severity of the preeclampsia. There were significant positive correlation between these markers and mean arterial pressure (MAP) and spot urine protein excretion. There was negative correlation between NGAL and apgar scores and fetal birth weight. Pregnancies with higher NGAL (OR: 4.89; 95% CI: 1.81-13.21) and higher PCT (OR: 6.67; 95% CI: 2.44-18.21) concentrations had higher risk for preeclampsia.Conclusion: NGAL and PCT may be potential biomarkers for preeclampsia. Their levels increase significantly in preeclampsia and they are related to the severity of the disease. These results are in agreement with the generalized endothelial damage and persistant inflammatory status in preeclampsia. NGAL may also be an indicator for adverse neonatal outcomes with decreased placental hypoperfusion. © 2014 Informa UK Ltd.
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    Maternal Serum S100-B, PAPP-A and IL-6 levels in severe preeclampsia
    (Springer Verlag, 2015) Artunc-Ulkumen B.; Guvenc Y.; Goker A.; Gozukara C.
    Aim: We aimed to investigate the relationship of maternal serum levels of S100-B, PAPP-A and IL-6 with severe preeclampsia. Materials and methods: This prospective case–control study consisted of 27 severe preeclamptic and 36 healthy singleton pregnancies. The groups were matched for parity, maternal age and body mass index. Maternal blood sampling for S100B, PAPP-A and IL-6 was performed at the morning after an overnight fasting. Results: S100-B concentrations were significantly higher in severe preeclampsia group (0.09 ± 0.05 vs. 0.13 ± 0.01 µg/L; p = 0.025). PAPP-A levels were higher (196.54 ± 21.56 vs. 208.80 ± 23.97 mIU/ml; p = 0.707) and IL-6 levels were lower in severe preeclamptic group (68.79 ± 29.89 vs. 37.30 ± 6.46 pg/ml; p = 0.372). AUC value for S100-B was calculated as 0.712. When cutoff level for serum S100-B for predicting severe preeclampsia was regarded as 0.0975 µg/L, sensitivity and specificity were found to be 81.4 % and 58.3 %, respectively. Pregnancies with ≥0.0975 µg/L S100-B levels had 12.75-fold increased risk for having CNS symptoms (OR 12.75; 95 % CI 2.69–60.28) and 3.27-fold increased risk for having HELLP syndrome (OR 3.27; 95 % CI 0.62–17.36). Conclusion: Our results suggest that serum S100B levels may be a potential marker in severe preeclampsia for the severity of hypoperfusion both in placenta and brain pointing at subsequent risk of organ failure. © 2015, Springer-Verlag Berlin Heidelberg.
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    Assessment of serum chemerin, vaspin and omentin-1 levels in patients with polycystic ovary syndrome
    (SAGE Publications Ltd, 2016) Guvenc Y.; Var A.; Goker A.; Kuscu N.K.
    Objective: To determine serum chemerin, vaspin and omentin-1 in overweight and normal weight patients with polycystic ovary syndrome (PCOS) and investigate the possible relationship between these adipokines and metabolic syndrome. Methods: This cross sectional study enrolled women with PCOS and healthy women. Serum chemerin, vaspin and omentin-1 were assessed by enzyme-linked immunosorbent assay methods. Results: Forty patients with PCOS and 30 healthy controls were included in the study. In the PCOS group, 18 women were overweight (body mass index [BMI] = 25.0–29.9 kg/m2) and 22 had normal weight (BMI = 18.5–24.9 kg/m2). Chemerin, total cholesterol, dehydroepiandrosterone sulphate and free androgen index (FAI) were significantly higher; and high-density lipoprotein cholesterol and sex hormone binding globulin were significantly lower in overweight PCOS patients compared with normal weight PCOS patients. A positive correlation was found between chemerin and BMI, triglyceride, insulin, homeostatic model assessment of insulin resistance and FAI in the PCOS group. There was no difference in serum chemerin, vaspin and omentin-1 between PCOS patients and healthy controls. Conclusion: Circulating chemerin was increased in overweight compared with normal weight PCOS patients. The most predictive variables for circulating chemerin in PCOS patients were BMI, FAI and age. © 2016, © The Author(s) 2016.
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    A nationwide multicentre study in Turkey for establishing reference intervals of haematological parameters with novel use of a panel of whole blood
    (Biochemia Medica, Editorial Office, 2017) Ozarda Y.; Ichihara K.; Bakan E.; Polat H.; Ozturk N.; Baygutalp N.K.; Taneli F.; Guvenc Y.; Ormen M.; Erbayraktar Z.; Aksoy N.; Sezen H.; Demir M.; Eskandari G.; Polat G.; Mete N.; Yuksel H.; Vatansev H.; Gun F.; Akin O.; Ceylan O.; Noyan T.; Gozlukaya O.; Aliyazicioglu Y.; Kahraman S.; Dirican M.; Tuncer G.O.; Kimura S.; Eker P.
    Introduction: A nationwide multicentre study was conducted to establish well-defined reference intervals (RIs) of haematological parameters for the Turkish population in consideration of sources of variation in reference values (RVs). Materials and methods: K2-EDTA whole blood samples (total of 3363) were collected from 12 laboratories. Sera were also collected for measurements of iron, UIBC, TIBC, and ferritin for use in the latent abnormal values exclusion (LAVE) method. The blood samples were analysed within 2 hours in each laboratory using Cell Dyn and Ruby (Abbott), LH780 (Beckman Coulter), or XT-2000i (Sysmex). A panel of freshly prepared blood from 40 healthy volunteers was measured in common to assess any analyser-dependent bias in the measurements. The SD ratio (SDR) based on ANOVA was used to judge the need for partitioning RVs. RIs were computed by the parametric method with/without applying the LAVE method. Results: Analyser-dependent bias was found for basophils (Bas), MCHC, RDW and MPV from the panel test results and thus those RIs were derived for each manufacturer. RIs were determined from all volunteers’ results for WBC, neutrophils, lymphocytes, monocytes, eosinophils, MCV, MCH and platelets. Gender-specific RIs were required for RBC, haemoglobin, haematocrit, iron, UIBC and ferritin. Region-specific RIs were required for RBC, haemoglobin, haematocrit, UIBC, and TIBC. Conclusions: With the novel use of a freshly prepared blood panel, manufacturer-specific RIs’ were derived for Bas, Bas%, MCHC, RDW and MPV. Regional differences in RIs were observed among the 7 regions of Turkey, which may be attributed to nutritional or environmental factors, including altitude. © by Croatian Society of Medical Biochemistry and Laboratory Medicine.
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    Visfatin: A potential biomarker for the early diagnosis and monitoring of acute coronary syndrome
    (Kare Publishing, 2019) Guvenc Y.; Cuhadar S.; Bayturan O.; Ulman C.; Horasan G.D.; Utuk O.; Acar M.
    Objectives: Acute coronary syndrome (ACS) is a major cause of mortality and morbidity worldwide; thus, early diagnosis is very important. The most common cause of ACS is the rupture of a vulnerable atherosclerotic plaque in the coronary artery, an occurrence in which inflammation plays a key role. The aim of the present study was to investigate visfatin as a proinflammatory biomarker in the early diagnosis and monitoring of ACS and to compare visfatin’s relationship with troponin T, tumor necrosis factor-alpha (TNF-α), and creatine kinase-MB (CK-MB). Methods: Sixty ACS patients and 30 healthy control subjects were enrolled in this study. One blood sample was drawn from the control participants, and 3 were obtained from the ACS patients at intervals 0-6 hours (T0), 6-12 hours (T1), and 12-24 (T2) hours from the start of chest pain. Serum visfatin, TNF-α, troponin T, and CK-MB levels were assessed. Visfatin and TNF-α levels were assessed using enzyme-linked immunosorbent assay testing, troponin T was evaluated using chemiluminescence, and CK-MB by enzymatic methods. Results: Serum TNF-α, troponin T, and CK-MB levels in the T0 blood samples were statistically significantly higher in the ACS patients compared with the controls (p=0.004, p<0.001, p<0.001, respectively). A significant positive correlation was observed between visfatin and troponin T (r=0.290, p=0.007) in the T0 samples. Visfatin concentrations were lower in the ACS group in the T0, T1 and T2 samples [4.01±6.23ng/mL, 1.80±3.47 ng/mL, and 1.72±2.67ng/mL, respectively; p=0.005; T0 >(T1=T2)]. Conclusion: Visfatin had a significant positive correlation with troponin T. Visfatin did not demonstrate a rise and fall pattern like the standard biomarkers in terms of monitoring the progress of ACS patients, as there was a significant decrease after the first 6 hours. Although visfatin did not demonstrate superiority to troponin, its efficiency in a multimarker panel merits further evaluation. The role of visfatin in the early phase of pathophysiological mechanisms requires additional investigation. © 2018 by International Journal of Medical Biochemistry.