Person: GÜLER, ERAY METİN
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Publication Open Access Serum obestatin and omentin levels in patients with diabetic nephropathy(2017-02-01) ZORLU, MEHMET; KISKAC, MUHARREM; Gueler, ERAY METİN; GUELTEPE, I.; YAVUZ, E.; CELIK, K.; KOCYIGIT, ABDÜRRAHİM; ZORLU, MEHMET; KISKAÇ, MUHARREM; GÜLER, ERAY METİN; KOÇYİĞİT, ABDÜRRAHİMIntroduction: Diabetic nephropathy is the leading cause of chronic kidney disease and accounts for almost 45% of all new patients requiring renal replacement therapy. Omentin and obestatin, two novel proteins were suggested to be associated with insulin resistance, type 2 diabetes and cardiovascular risk factors. Thus, we postulated that they may also have an association with diabetic nephropathy which is known to be an independent cardiovascular risk factor. In order to investigate such an association we compared serum omentin and obestatin levels in type 2 diabetic patients with normoalbuminuria (NA) and macroalbuminuria (MA). Materials and Methods: A total of 81 type 2 diabetic patients were separated into two groups according to their proteinuria status; patients with NA (n = 39) and patients with MA (n = 42). Two groups were compared in terms of serum omentin and obestatin levels. Results: While serum omentin levels did not differ among two groups (P = 0.407), serum obestatin levels were significantly higher in MA group (P = 0.001). Conclusion: The results of this study showed that higher serum levels of obestatin were associated with macro albuminuria suggesting that obestatin may have a role in underlying pathogenic mechanisms that leads to diabetic nephropathyPublication Metadata only Raftlin, presepsin levels and thiol-disulfide homeostasis in acute appendicitis: A pilot study(2018-11-01) KOÇYİĞİT, ABDÜRRAHİM; ERSOY, YELİZ EMİNE; SELEK, ŞAHBETTİN; SÜMBÜL, BİLGE; ÖZER, ÖMER FARUK; GÜLER, ERAY METİN; MERAL, İSMAİL; YİĞİT, MEHMET; ÖZER, ÖMER FARUK; GÜLER, ERAY METİN; KOÇYİĞİT, ABDÜRRAHİM; MERAL, İSMAİL; SÜMBÜL, BİLGE; SELEK, ŞAHABETTİN; ERSOY, YELIZ EMINEObjective: To investigate some of the new inflammatory and oxidative stress markers in acute appendicitis.Publication Metadata only Synthesis of Oleanolic Acid Analogues and Their Cytotoxic Effects on 3T3 Cell Line(2018-01-01) Tuncay, Salih; Kocyigit, ABDÜRRAHİM; SEÇEN, Hasan; Ocal, Nuket; Topcu, GÜLAÇTI; Guler, ERAY METİN; ŞENOL, HALIL; GÜLER, ERAY METİN; KOÇYİĞİT, ABDÜRRAHİM; TOPÇU, GÜLAÇTIBackground: Oleanolic acid (OA) is a known natural compound with many important biological activities. Thirteen oleanolic acid derivatives linked at C-3 and C-28 were synthesized and their structures were confirmed by H-1- and C-13 NMR and mass spectral analyses. Among them, compounds 4, 6, 8-10, 12, 13 were synthesized for the first time. They were evaluated for their cytotoxic activity. They showed proliferative effect at low concentrations while cytotoxic effect was observed at high concentrations in a dose dependent manner.Publication Open Access Plasma lipoxin a4 levels in childhood chronic spontaneous urticaria(2018-01-01) DİLEK, FATİH; ÖZÇEKER, DENİZ; GÜLER, ERAY METİN; ÖZKAYA, EMİN; YAZICI, MEBRURE; TAMAY, ZEYNEP ÜLKER; KOÇYİĞİT, ABDURRAHİM; GÜLER, NERMİN; GÜLER, ERAY METİN; ÖZKAYA, EMİN; YAZICI, MEBRURE; KOÇYİĞİT, ABDÜRRAHİMDilek F, Özçeker D, Güler EM, Özkaya E, Yazıcı M, Tamay Z, Koçyiğit A, Güler N. Plasma lipoxin A4 levels in childhood chronic spontaneous urticaria. Turk J Pediatr 2018; 60: 527-534. Chronic spontaneous urticaria (CSU) is an idiopathic inflammatory disorder. Despite great research progress, the pathogenesis of the disease is still not fully understood. Lipoxins (LXs) are autacoid lipid metabolites that are the first discovered members of a new genus named called `specialized proresolving mediators`. In this study, we aimed to investigate the possible role of LXA4 in the pathogenesis of CSU. Forty-two children with CSU and 25 healthy children were enrolled in the study. The demographic and clinical features of patients were evaluated, autologous serum skin tests (ASSTs), and routine laboratory assessments were performed. Disease activity was determined using the urticaria activity score. An enzyme-linked immunosorbent assay was used to evaluate LXA4 plasma levels. The median value of plasma LXA4 was found to be 60.8 ng/ml (interquartile range, 48.1-71.8) in CSU patients and 137.4 ng/ml (121.4-150.8) in the control group. The difference between the groups was statistically significant (p < 0.001). Additionally, the median plasma LXA4 levels in the ASST-positive patients were significantly reduced compared to the ASST-negative ones (45.8 [36.7-67.6] versus 63.8 [58.3-78.9] ng/ml, respectively, p < 0.05). Our results showed that diminished LXA4 biosynthesis may be a critical part of CSU pathogenesis in children, especially in patients with an autoimmune component.Publication Open Access Relationship between diabetic polyneuropathy, serum visfatin, and oxidative stress biomarkers(2020-07-01T00:00:00Z) GÜLER, Eray Metin; BÜYÜKAYDIN, BANU; Karaaslan, Tahsin; OLGAÇ, ATİLLA; ZORLU, MEHMET; KISKAÇ, MUHARREM; KOÇYİĞİT, ABDÜRRAHİM; BÜYÜKAYDIN, BANU; GÜLER, ERAY METİN; OLGAÇ, ATİLLA; ZORLU, MEHMET; KISKAÇ, MUHARREM; KOÇYİĞİT, ABDÜRRAHİMBackground: Diabetic polyneuropathy is a very common complication of diabetes. Numerous studies are available in terms of pathogenesis. But examination methods with low reliability are still not standardized and generally time consuming. High-sensitive, easy-to-access methods are expected. Biochemical markers are one of the subjects of research. We aimed to discover a potential biomarker that can be used for this purpose in patients with diabetes who have not yet developed symptoms of neuropathy. Aim: To determine the place and availability of visfatin and thiol-disulfide homeostasis in this disorder. Methods: A total of 392 patients with type 2 diabetes mellitus were included in the study. The polyneuropathy clinical signs were evaluated with the Subjective Peripheral Neuropathy Screen Questionnaire and Michigan Neuropathy Screening Instrument questionnaire and examination. The biochemical parameters, oxidative stress markers, visfatin, and thiol-disulfide homeostasis were analyzed and correlated with each other and clinical signs. Results: Subjective Peripheral Neuropathy Screen Questionnaire and Michigan Neuropathy Screening Instrument questionnaire with examination scores were correlated with each other and diabetes duration (P < 0.005). Neuropathy related symptoms were present in 20.7% of the patients, but neuropathy related findings were observed in 43.9% of the patients. Serum glucose, glycated hemoglobin, and visfatin were positively correlated with each other. Also, these parameters were positively correlated with the total oxidative stress index. Total and native thiol was positively correlated with total antioxidant status and negatively with oxidant status. Inversely thiol-disulfide positively correlated with higher glucose and oxidant status and negatively with total antioxidant status (P < 0.005). There was no correlation between visfatin and thiol-disulphide (P = 0.092, r = 0.086). However, a significant negative correlation was observed between visfatin and total with native thiol (P < 0.005, r = -0.338), (P < 0.005, r = -0.448). Conclusion: Diagnosis of neuropathy is one of the issues studied in patients with diabetes. Visfatin and thiol-disulfide balance were analyzed for the first time in this study with inspiring results.Publication Open Access Comparison of Platelet-Rich Plasma-Impregnated Suture Material with Low and High Platelet Concentration to Improve Colonic Anastomotic Wound Healing in Rats.(2020-05-26T00:00:00Z) Aydin, MA; Guler, Eray Metin; Demiroz, AS; Aydin, MF; Saglam, G; GÜLER, ERAY METİNObjective. This study was designed to investigate the impact of using suture material impregnated with platelet-rich plasma (PRP) in different platelet concentrations on colonic anastomotic wound healing in rats. Methods. A total of 24 Sprague Dawley female rats were separated into 3 groups (n = 8 for each) including the control group (CON; standard vicryl suture repair), the low platelet concentrate PRP group (L-PRP; suture material impregnated with PRP containing average 2.7-fold (range, 2.0 to 3.1) higher amount of platelets vs. control), and the high platelet concentrate PRP group (H-PRP; suture material impregnated with PRP containing average 5.1-fold (range, 4.8 to 5.4) higher amount of platelets vs. control). Rats were sacrificed on the postoperative 7th day for analysis of colonic anastomosis region including macroscopic observation, measurement of anastomotic bursting pressure (ABP), and the hydroxyproline levels and histopathological findings in colon tissue samples. Results. Total injury scores were significantly lower in the L-PRP and H-PRP groups than those in the control group (median (range) 13.00 (7.00) and 11.50 (6.00) vs. 15.50 (4.00), p < 0:05 and p < 0:01, respectively). ABP values (180.00 (49.00) vs. 124.00 (62.00) and 121.00 (57.00) mmHg, p < 0:001 for each) and tissue hydroxyproline levels (0.56 (0.37) vs. 0.25 (0.17) and 0.39 (0.10) μg/mg tissue, p < 0:001 and p < 0:05, respectively) were significantly higher in the L-PRP group as compared with those in the control and H-PRP groups. Conclusion. In conclusion, our findings revealed PRP application to colonic anastomosis sutures to promote the anastomotic healing process. The platelet concentration of PRP seems to have a significant impact on the outcome with superior efficacy of L-PRP over H-PRP in terms of bursting pressures and collagen concentration at the anastomotic site.Publication Open Access In Vitro Hormetic Effect Investigation of Thymol on Human Fibroblast and Gastric Adenocarcinoma Cells.(2020-07-17T00:00:00Z) Günes-Bayir, A; Kocyigit, A; Guler, Eray Metin; Dadak, A; GÜNEŞ BAYIR, AYŞE; KOÇYİĞİT, ABDÜRRAHİM; GÜLER, ERAY METİNThe concept of hormesis includes a biphasic cellular dose-response to a xenobiotic stimulus defined by low dose beneficial and high dose inhibitory or toxic effects. In the present study, an attempt has been made to help elucidate the beneficial and detrimental effects of thymol on different cell types by evaluating and comparing the impact of various thymol doses on cancerous (AGS) and healthy (WS-1) cells. Cytotoxic, genotoxic, and apoptotic effects, as well as levels of reactive oxygen species and glutathione were studied in both cell lines exposed to thymol (0-600 mu M) for 24 h. The results showed significant differences in cell viability of AGS compared to WS-1 cells exposed to thymol. The differences observed were statistically significant at all doses applied (P <= 0.001) and revealed hormetic thymol effects on WS-1 cells, whereas toxic effects on AGS cells were detectable at all thymol concentrations. Thymol at low concentrations provides antioxidative protection to WS-1 cells in vitro while already inducing toxic effects in AGS cells. In that sense, the findings of the present study suggest that thymol exerts a dose-dependent hormetic impact on different cell types, thereby providing crucial information for future in vivo studies investigating the therapeutic potential of thymol.Publication Open Access Plasma total thiol pool in children with asthma: Modulation during montelukast monotherapy(2016-03-01) DILEK, Fatih; Ozkaya, EMİN; Kocyigit, ABDÜRRAHİM; Yazici, MEBRURE; Guler, ERAY METİN; DUNDAROZ, Mehmet Rusen; ÖZKAYA, EMİN; KOÇYİĞİT, ABDÜRRAHİM; YAZICI, MEBRURE; GÜLER, ERAY METİNBackground: Inflammation, which is a hallmark of asthma, is one of the main sources of oxidative stress in the human body. Thiols are powerful antioxidants that protect cells against the consequences of oxidative stress. We aimed to investigate whether asthma and montelukast monotherapy affect the total plasma thiol pool in children. Methods: A total of 60 children with asthma and 35 healthy controls participated in the study. Group I consisted of newly diagnosed asthmatics who did not have regular anti-asthmatic therapy previously. Group II consisted of patients who had been undertaking montelukast monotherapy regularly for at least 4 months. Plasma total antioxidant status (TAS) and plasma total thiol (PTT) were measured using spectrophotometric methods. Results: Bronchial asthma patients in both groups I and II had decreased median TAS levels compared with the control group (1.59 [interquartile range, 1.04–1.70] and 1.67 [1.50–1.75] vs. 2.98 [2.76–3.16] Trolox equiv./L, respectively; P <0.001). Group I had decreased PTT concentrations compared with the control group (0.18 [0.16–0.20] vs. 0.21 [0.19–0.22] mmol/L; P <0.001), and group II had similar PTT levels to the control group (0.20 [0.17–0.22] mmol/L; P >0.05). In addition, the median TAS and PTT levels for groups I and II were not statistically different (P >0.05). There was a positive correlation between TAS and PTT levels (rho = 0.38, P <0.05) in group I. Conclusion: In order to balance the oxidative stress, both TAS and PTT which are markers of the antioxidant system are reduced in children with asthma. Montelukast monotherapy can limit oxidative stress and thus restore PTT levels but not TAS levels in asthmatic children.Publication Open Access Quercus pyrenaica Honeydew Honey With High Phenolic Contents Cause DNA Damage, Apoptosis, and Cell Death Through Generation of Reactive Oxygen Species in Gastric Adenocarcinoma Cells(2019-09-01) KOÇYİĞİT, ABDÜRRAHİM; Aydogdu, Gokhan; BALKAN, EZGİ; GÜLER, Eray Metin; BULUT, HURİ; KÖKTAŞOĞLU, FATMANUR; Goeren, AHMET CEYHAN; Atayoglu, Ali Timucin; KOÇYİĞİT, ABDÜRRAHİM; BALKAN, EZGİ; YENİGÜN, VILDAN BETÜL; GÜLER, ERAY METİN; BULUT, HURI; KÖKTAŞOĞLU, FATMANUR; GÖREN, AHMET CEYHANMany studies have shown that honey with high phenolic contents prevents cancer formation. Furthermore, recent studies have demonstrated that honey can be used for the treatment of cancer as well as cancer prevention. Antineoplastic effects of honey are often associated with their antioxidant phenolic contents. However, very few studies have dealt with the association of phenolic contents of honeys in terms of antiproliferative effects. The aim of this study was, therefore, to elucidate the cytotoxic, genotoxic, apoptotic, and reactive oxygen species (ROS) generating effects of honey samples on the basis of their phenolic and flavonoid contents. Fourteen different honey varieties were collected from various parts of Turkey, and their characteristics regarding total phenols, flavonoids, and antioxidant contents were determined to test their effects on gastric cancer cells (AGS). For convenience, 2 honey varieties were selected, namely, Ida Mountains Quercus pyrenaica honeydew honey (QPHH-IM) having the highest phenolic and antioxidant content and Canakkale multifloral honey (MFH-C) with the lowest phenolic and antioxidant content. Levels of 11 different phenolic compounds in QPHH-IM and MFH-C samples were determined by LC-MS/MS. AGS cells were incubated with different concentrations of QPHH-IM and MFH-C for 24 hours, then the cell viability, DNA damage, apoptosis, and generation of ROS were determined. We found that QPHH-IM had more cytotoxic, genotoxic, and apoptotic effects than that of MFH-C. We think that these effects are probably related to pro-oxidant activities due to the high phenolic contents present. Therefore, further research on high-phenolic honey may contribute to the future development of cancer therapeutics.Publication Open Access Evaluation of residual monomer release and toxicity of self-adhesive resin cements(2018-02-01) Kurt, Aysegul; ALTINTAŞ, SUBUTAY HAN; KIZILTAS, Mustafa Volkan; TEKKELI, Serife Evrim; Guler, ERAY METİN; Kocyigit, ABDÜRRAHİM; USUMEZ, Aslihan; TEKKELİ, ŞERİFE EVRİM; GÜLER, ERAY METİN; KOÇYİĞİT, ABDÜRRAHİMThe aim of this study was to evaluate the amount of leached residual monomers from self-adhesive resin cements and evaluate their toxicity in-vitro. A total of 60 disk-shaped specimens (5 mm in diameter and 0.5 mm in thickness) were prepared from each cement (RelyX U200, SpeedCEM, G-Cem) (n=20). Specimens were immersed in artificial saliva and the amount of released monomers [urethane dimethacrylate (UDMA) and triethyleneglycol dimethacrylate (TEGDMA)] was identified. Then, the cytotoxicity and genotoxicity effect on cells were evaluated using the defined amounts of released monomers from cements. The highest monomer release was detected in G-Cem (p<0.05). The highest cytotoxicity value was identified from SpeedCEM (p<0.01) and the highest genotoxicity values were calculated from RelyX U200 (p<0.05). Released UDMA and TEGDMA from self-adhesive resin cements induced cytotoxicity and genotoxicity effect on cells.