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Dive into the research topics where Berrak Guven is active.

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Featured researches published by Berrak Guven.


Clinical Chemistry and Laboratory Medicine | 2011

Inflammatory markers in preeclamptic patients.

Murat Can; Eray Sancar; Muge Harma; Berrak Guven; Gorkem Mungan; Serefden Acikgoz

Abstract Background: Preeclampsia is characterized by hypertension and proteinuria that begins in the second half of pregnancy. Endothelial dysfunction and trophoblastic hypoperfusion seen in preeclampsia suggested to be part of an increased maternal inflammatory response to pregnancy. In this study, we aimed to evaluate some inflammatory markers in pre-eclamptic and normotensive pregnants. Methods: The study included 36 cases with mild preeclamp-sia, 36 cases with severe preeclampsia and 33 cases of normotensive pregnant. High sensitive C-reactive protein (hsCRP) and serum amyloid A (SAA) were measured by enzyme-linked immunosorbent assays, serum procalcitonin was measured by enzyme-linked fluorescent immunassay. Mean arterial pressure (MAP) was used as an indicator of the severity of the disease. Results: In severe preeclampsia group hsCRP, serum amyloid A and procalcitonin levels were significantly higher than mild preeclamptic and normotensive groups. SAA and hsCRP levels were higher in mild preeclamptic group when compared with normotensive pregnant but no significant difference was found in procalcitonin between these groups. There were significant correlations betweeen hsCRP, SAA, procalcitonin and MAP. Conclusions: The results confirm that inflammatory reactions are closely associated with preeclampsia.


Mediators of Inflammation | 2013

Levels of Oxidized LDL, Estrogens, and Progesterone in Placenta Tissues and Serum Paraoxonase Activity in Preeclampsia

Şerefden Açıkgöz; Ülkü Özmen Bayar; Murat Can; Berrak Guven; Gorkem Mungan; Suat Serhan Altıntepe Dogan; Vildan Sumbuloglu

In vitro literature studies have suggested that atherosclerotic oxidized low density lipoprotein (OxLDL) inhibits trophoblast invasion. The objective of this study was to determine the levels of OxLDL and to examine the relationship between antioxidative estradiol, estriol, and prooxidative progestin in normal and preeclamptic placental tissues and measure the serum activity of antioxidative paraoxonase (PON1). The study included 30 preeclamptic and 32 normal pregnant women. OxLDL was determined with ELISA, estradiol, unconjugated estriol, and progesterone that were determined with chemiluminescence method in placental tissues. Serum PON1 activity was determined with spectrophotometric method. Levels of OxLDL (P = 0.027), estriol (P < 0.001), estradiol (P = 0.008), and progesterone (P = 0.009) were lower in the placental tissues of preeclamptic group compared to the normal pregnant women. Serum PON1 activity was higher in preeclamptic group (P = 0.040) and preeclamptic group without intrauterine growth restriction (P = 0.008) compared to normal pregnant women. Tissue estriol of preeclamptic group without/with IUGR (P < 0.001, P = 0.002) was lower than the normal group. Results of our study suggest that the events leading to fetoplacental insufficiency lead to a reduction in the levels of estriol limit deposition of OxLDL in placental tissues. The serum PON1 activity is probably important in the inhibition of OxLDL in preeclampsia.


Tissue & Cell | 2014

Oxidative stress and apoptosis in preeclampsia

Murat Can; Berrak Guven; Sibel Bektas; Ilker Arikan

We aimed to determine the oxidative stress and antioxidant status in preeclamptic placenta. Also, we investigated the apoptotic index of villous trophoblast and proliferation index of cytotrophoblasts. The study included 32 pregnant with preeclampsia and 31 normotensive healthy pregnant women. Malondialdehyde (MDA) and total antioxidant status (TAS) levels were measured in the placenta. For detection of apoptosis and proliferation in trophoblast, apoptosis protease activating factor 1 (APAF-1) and Ki-67 were used. Placental MDA levels in preeclamptic women were significantly higher than normal pregnancies (p=0.002). There was no significant difference between the groups in the TAS levels of placenta (p=0.773). Also, the apoptotic index in villous trophoblasts increased (p<0.001), but proliferation index did not change in preeclampsia (p=0.850). Increased oxidative stress and apoptosis in pathological placenta are not balanced by antioxidant systems and proliferation mechanisms.


Journal of Radiation Research | 2013

Effects of ozone oxidative preconditioning on radiation-induced organ damage in rats

Fatma Ayca Gultekin; Bekir Hakan Bakkal; Berrak Guven; Ilhan Tasdoven; Sibel Bektas; Murat Can; Mustafa Comert

Because radiation-induced cellular damage is attributed primarily to harmful effects of free radicals, molecules with direct free radical scavenging properties are particularly promising as radioprotectors. It has been demonstrated that controlled ozone administration may promote an adaptation to oxidative stress, preventing the damage induced by reactive oxygen species. Thus, we hypothesized that ozone would ameliorate oxidative damage caused by total body irradiation (TBI) with a single dose of 6 Gy in rat liver and ileum tissues. Rats were randomly divided into groups as follows: control group; saline-treated and irradiated (IR) groups; and ozone oxidative preconditioning (OOP) and IR groups. Animals were exposed to TBI after a 5-day intraperitoneal pretreatment with either saline or ozone (1 mg/kg/day). They were decapitated at either 6 h or 72 h after TBI. Plasma, liver and ileum samples were obtained. Serum AST, ALT and TNF-α levels were elevated in the IR groups compared with the control group and were decreased after treatment with OOP. TBI resulted in a significant increase in the levels of MDA in the liver and ileal tissues and a decrease of SOD activities. The results demonstrated that the levels of MDA liver and ileal tissues in irradiated rats that were pretreated with ozone were significantly decreased, while SOD activities were significantly increased. OOP reversed all histopathological alterations induced by irradiation. In conclusion, data obtained from this study indicated that ozone could increase the endogenous antioxidant defense mechanism in rats and there by protect the animals from radiation-induced organ toxicity.


World Journal of Gastroenterology | 2015

Assessment of the correlation between serum prolidase and alpha-fetoprotein levels in patients with hepatocellular carcinoma

Sevil Uygun Ilikhan; Muammer Bilici; Hatice Sahin; Ayşe Semra Demir Akca; Murat Can; Ibrahim Ilker Oz; Berrak Guven; M. Çağatay Büyükuysal; Yucel Ustundag

AIM To determine the predictive value of increased prolidase activity that reflects increased collagen turnover in patients with hepatocellular carcinoma (HCC). METHODS Sixty-eight patients with HCC (mean age of 69.1 ± 10.1), 31 cirrhosis patients (mean age of 59.3 ± 6.3) and 33 healthy volunteers (mean age of 51.4 ± 12.6) were enrolled in this study. Univariate and multivariate analysis were used to evaluate the association of serum α-fetoprotein (AFP) values with HCC clinicopathological features, such as tumor size, number and presence of vascular and macrovascular invasion. The patients with HCC were divided into groups according to tumor size, number and presence of vascular invasion (diameters; ≤ 3 cm, 3-5 cm and ≥ 5 cm, number; 1, 2 and ≥ 3, macrovascular invasion; yes/no). Barcelona-clinic liver cancer (BCLC) criteria were used to stage HCC patients. Serum samples for measurement of prolidase and alpha-fetoprotein levels were kept at -80 °C until use. Prolidase levels were measured spectrophotometrically and AFP concentrations were determined by a chemiluminescence immunometric commercial diagnostic assay. RESULTS In patients with HCC, prolidase and AFP values were evaluated according to tumor size, number, presence of macrovascular invasion and BCLC staging classification. Prolidase values were significantly higher in patients with HCC compared with controls (P < 0.001). Prolidase levels were significantly associated with tumor size and number (P < 0.001, P = 0.002, respectively). Prolidase levels also differed in patients in terms of BCLC staging classification (P < 0.001). Furthermore the prolidase levels in HCC patients showed a significant difference compared with patients with cirrhosis (P < 0.001). In HCC patients grouped according to tumor size, number and BCLC staging classification, AFP values differed separately (P = 0.032, P = 0.038, P = 0.015, respectively). In patients with HCC, there was a significant correlation (r = 0.616; P < 0.001) between prolidase and AFP values in terms of tumor size, number and BCLC staging classification, whereas the presence of macrovascular invasion did not show a positive association with serum prolidase and AFP levels. CONCLUSION Considering the levels of both serum prolidase and AFP could contribute to the early diagnosing of hepatocellular carcinoma.


European Neurology | 2013

Ischemia Modified Albumin and Plasma Oxidative Stress Markers in Alzheimer's Disease

Murat Can; Figen Varlibas; Berrak Guven; Ozkan Akhan; Gülbün Yüksel

Objectives: The objective of this study was to determine ischemia modified albumin (IMA) and oxidant status in Alzheimers disease (AD). Therefore, we evaluated the IMA and oxidant status by measuring serum uric acid, albumin and gamma-glutamyltransferase (GGT) in AD. Methods: The plasma albumin, uric acid, GGT and IMA levels were measured by spectrophotometric methods in 32 AD patients and 32 healthy controls. The Mini Mental Status Examination and Clinical Dementia Rating Scale were used to evaluate the cognitive functions of AD patients. Results: AD patients had significantly higher IMA levels as compared to those of the controls respectively. Uric acid concentrations were significantly decreased and GGT values were significantly increased in AD when compared with control group. Albumin levels of the patients were also compared and no significant difference was detected. Conclusion: Oxidative stress and IMA levels rise in AD. However, large prospective studies are required to understand the mechanisms leading to increased IMA levels during AD, whether preceded or not by AD.


Journal of Reproductive Immunology | 2016

Is Xanthine oxidase activity in polycystic ovary syndrome associated with inflammatory and cardiovascular risk factors

Hatice Işık; Oner Aynioglu; Hakan Tımur; Ahmet Sahbaz; Muge Harma; Murat Can; Berrak Guven; Hüsnü Alptekin; Furuzan Kokturk

The aim of this study is to examine women with polycystic ovary syndrome (PCOS) to determine the relationship between xanthine oxidase (XO) and oxidative stress, inflammatory status, and various clinical and biochemical parameters. In this cross-sectional study a total of 83 women including 45 PCOS patients and 38 healthy women were enrolled. We collected blood samples for XO and superoxide dismutase (SOD) activity, hormone levels, cholesterol values, and inflammatory markers. Body mass index (BMI) , waist-to-hip ratio (WHR), and blood pressure were assessed. Blood samples were taken for hormonal levels, cholesterol levels, fasting plasma glucose (FPG), fasting plasma insulin (FPI), homeostatic model assessment-insulin resistance (HOMA-IR) index, quantitative insulin sensitivity check index (QUICKI), C-reactive protein (CRP), white blood cell and neutrophil counts, XO and SOD activities. The basal hormone levels, triglyceride (TG) levels, TG/HDL-C (high density lipoprotein-cholesterol) ratios FPG, FPI and HOMA-IR levels were higher in PCOS patients compared to controls (p<0.05). Platelet and plateletcrit (PCT) values, CRP, and XO activity were significantly increased, however SOD activity was decreased in PCOS patients (p<0.001). XO activity was positively correlated with LH/FSH and TG/HDL ratios, CRP, PCT, FPG, FPI, and HOMA-IR, and negatively correlated with QUICKI levels. In conclusion, XO is a useful marker to assess oxidative stress in PCOS patients. Positive correlations between XO and inflammatory markers and cardiovascular disease risk factors suggest that XO plays an important role in the pathogenesis of PCOS and its metabolic complications.


Journal of Periodontology | 2015

Gingival Crevicular Fluid Levels of Sclerostin, Osteoprotegerin, and Receptor Activator of Nuclear Factor-κB Ligand in Periodontitis.

Umut Balli; Ahmet Aydogdu; Figen Öngöz Dede; Çiğdem Coşkun Türer; Berrak Guven

BACKGROUND To investigate changes in the levels and relative ratios of sclerostin, osteoprotegerin (OPG), and receptor activator of nuclear factor-κB ligand (RANKL) in the gingival crevicular fluid (GCF) of patients with periodontitis after non-surgical periodontal treatment. METHODS Fifty-four individuals (27 healthy controls and 27 patients with chronic periodontitis [CP]) were enrolled in the study. Periodontitis patients received non-surgical periodontal therapy. GCF sampling and clinical periodontal parameters were assessed before and 6 weeks after therapy. Sclerostin, OPG, and RANKL levels were measured by enzyme-linked immunosorbent assay, and their relative ratios were calculated. RESULTS Total amounts and concentrations of sclerostin were significantly higher in patients with CP than in healthy individuals (P <0.025) and decreased after treatment (P <0.05). The RANKL/OPG ratio was significantly lower in healthy individuals than in patients with periodontitis before and after treatment (P <0.025), but no significant difference was observed in patients with periodontitis after treatment (P >0.05). The sclerostin/OPG and sclerostin/RANKL ratios were significantly lower in healthy individuals than in patients with periodontitis before and after treatment (P <0.025) and decreased in patients with periodontitis after treatment (P <0.05). CONCLUSIONS The GCF sclerostin level may be more reliable than the RANKL/OPG ratio as a diagnostic and prognostic marker of periodontal disease and treatment outcome. Regulation of sclerostin levels may aid the development of new therapeutic strategies for the treatment of periodontal disease.


Brazilian Journal of Medical and Biological Research | 2013

Effect of ozone oxidative preconditioning in preventing early radiation-induced lung injury in rats.

Bekir Hakan Bakkal; Fatma Ayca Gultekin; Berrak Guven; U.O. Turkcu; Sibel Bektas; Murat Can

Ionizing radiation causes its biological effects mainly through oxidative damage induced by reactive oxygen species. Previous studies showed that ozone oxidative preconditioning attenuated pathophysiological events mediated by reactive oxygen species. As inhalation of ozone induces lung injury, the aim of this study was to examine whether ozone oxidative preconditioning potentiates or attenuates the effects of irradiation on the lung. Rats were subjected to total body irradiation, with or without treatment with ozone oxidative preconditioning (0.72 mg/kg). Serum proinflammatory cytokine levels, oxidative damage markers, and histopathological analysis were compared at 6 and 72 h after total body irradiation. Irradiation significantly increased lung malondialdehyde levels as an end-product of lipoperoxidation. Irradiation also significantly decreased lung superoxide dismutase activity, which is an indicator of the generation of oxidative stress and an early protective response to oxidative damage. Ozone oxidative preconditioning plus irradiation significantly decreased malondialdehyde levels and increased the activity of superoxide dismutase, which might indicate protection of the lung from radiation-induced lung injury. Serum tumor necrosis factor alpha and interleukin-1 beta levels, which increased significantly following total body irradiation, were decreased with ozone oxidative preconditioning. Moreover, ozone oxidative preconditioning was able to ameliorate radiation-induced lung injury assessed by histopathological evaluation. In conclusion, ozone oxidative preconditioning, repeated low-dose intraperitoneal administration of ozone, did not exacerbate radiation-induced lung injury, and, on the contrary, it provided protection against radiation-induced lung damage.


Kaohsiung Journal of Medical Sciences | 2016

The effects of tadalafil and pentoxifylline on apoptosis and nitric oxide synthase in liver ischemia/reperfusion injury

Sibel Bektas; Kemal Karakaya; Murat Can; Burak Bahadir; Berrak Guven; Nilsen Erdogan; Sukru Oguz Ozdamar

The aim of this study was to investigate the effects of tadalafil (TDF) and pentoxifylline (PTX) on hepatic apoptosis and the expressions of endothelial and inducible nitric oxide synthases (eNOS and iNOS) after liver ischemia/reperfusion (IR). Forty Wistar albino rats were randomly divided into five groups (n = 8) as follows: sham group; IR group with ischemia/reperfusion alone; low‐dose and high‐dose TDF groups received 2.5 mg/kg and 10 mg/kg TDF, respectively; and PTX group received 40 mg/kg PTX. Blood was collected for the analysis of serum alanine aminotransferase, aspartate aminotransferase, γ‐glutamyl transferase, uric acid, malondialdehyde (MDA), and total antioxidant capacity (TAC). MDA and TAC also were measured in liver tissue. Histopathological examination was performed to assess the severity of hepatic injury. Apoptosis was evaluated using the apoptosis protease‐activating factor 1 (APAF‐1) antibody; the expressions of eNOS and iNOS were also assessed by immunohistochemistry in all groups. Serum alanine aminotransferase, aspartate aminotransferase, γ‐glutamyl transferase, uric acid, MDA, and TAC, tissue MDA and TAC levels, hepatic injury, and score for extent and for intensity of eNOS, iNOS, and apoptosis protease‐activating factor 1 were significantly different in TDF and PTX groups compared to the IR group. High dose‐TDF and PTX have the best protective effect on IR‐induced liver tissue damage. This study showed that TDF and PTX supplementation may be helpful in preventing free oxygen radical damage, lipid peroxidation, hepatocyte necrosis, and apoptosis in liver IR injury and minimizing liver damage.

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Murat Can

Zonguldak Karaelmas University

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Gorkem Mungan

Zonguldak Karaelmas University

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Serefden Acikgoz

Zonguldak Karaelmas University

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Sibel Bektas

Zonguldak Karaelmas University

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Umut Balli

Zonguldak Karaelmas University

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Çiğdem Coşkun Türer

Zonguldak Karaelmas University

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Furuzan Kokturk

Zonguldak Karaelmas University

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Zeynep Eskici

Zonguldak Karaelmas University

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Şerefden Açıkgöz

Zonguldak Karaelmas University

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Bekir Hakan Bakkal

Zonguldak Karaelmas University

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