Person: YEGEN, BERRAK
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YEGEN
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BERRAK
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Publication Metadata only Nesfatin-1 treatment preserves antioxidant status and attenuates renal fibrosis in rats with unilateral ureteral obstruction(2022-06-01) ÇETİNEL, ŞULE; YEGEN, BERRAK; KAYA, ÖZLEM TUĞÇE; ÖZBEYLİ, DİLEK; Tezcan N., Özdemir-Kumral Z. N., Yenal N. Ö., Çilingir-Kaya Ö. T., Virlan A. T., Özbeyli D., Çetinel Ş., Yeğen B., Koç M.Background Nesfatin-1 (NES-1), an anorexigenic peptide, was reported to have anti-inflammatory and anti-apoptotic actions in several inflammation models. Methods To elucidate potential renoprotective effects of NES-1, unilateral ureteral obstruction (UUO) was induced in male Sprague Dawley rats by ligating left ureters. The rats were injected intraperitoneally with either saline (SL) or NES-1 (10 mu g/kg/day) for 7 or 14 days (n = 8 in each group). On the 7th or 14th day, obstructed kidneys were removed for the isolation of leucocytes for flow-cytometric analysis and the assessments of biochemical and histopathological changes. Results Opposite to glutathione levels, renal myeloperoxidase activity in the SL-treated UUO group was significantly increased compared with the sham-operated group, while NES-1 treatment abolished the elevation. The percentages of CD8+/CD4+ T-lymphocytes infiltrating the obstructed kidneys were increased in the SL-treated groups but treatment with NES-1 did not prevent lymphocyte infiltration. Elevated tumour necrosis factor-alpha (TNF-alpha) levels in SL-treated UUO group were decreased with NES-1. Although total degeneration scores were similarly increased in all UUO groups, tubular dilatation scores were significantly increased in UUO groups and lowered by NES-1 only in the 7-day treated group. Elevated interstitial fibrosis scores in the SL-treated groups were decreased in both 7- and 14-day NES-1 treated groups, while alpha-smooth muscle actin (alpha-SMA) and apoptosis scores were depressed in both NES-1 treated groups. Conclusion The present data demonstrate that UUO-induced renal fibrosis is ameliorated by NES-1, which appears to involve the inhibition of neutrophil infiltration and thereby amelioration of oxidative stress and inflammation. These data suggest that NES-1 may have a regulatory role in protecting the kidneys against obstruction-induced renal injury.Publication Open Access Cerrahi menopoz oluşturulmuş sıçanların karaciğer ve böbrek dokularında oksidan/antioksidan dengenin korunmasında egzersizin ve östrojenin yararlı etkileri(2022-09-01) YÜKSEL, MERAL; ERCAN, FERİHA; YILDIRIM, ALPER; YEGEN, BERRAK; Tamer S. A. , Levent N., Yüksel M., Ercan F., Yıldırım A., Yegen B.Amaç: Bu çalışmanın amacı cerrahi olarak menopoz oluşturulan sıçanların böbrek ve karaciğerlerinde gözlenen histopatolojik ve fonksiyonel değişiklikleri ve östrojen veya egzersizin ya da östrojen-egzersiz kombinasyonunun oksidan hasar üzerine etkilerini araştırmaktır.Materyal ve Metot: Anestezi altında Sprague Dawley dişi sıçanlara (n=32) bilateral overiektomi uygulandı ve tüm sıçanlar rastgele olarak iki gruba ayrıldı. Sıçanların yarısına normal içme suyu, diğer yarısının içme sularına östrojen (1mg/kg/gün) eklendi. İki hafta sonra gruplar kendi içlerinde sedanter ve egzersiz (5 gün/hafta, 30 daki-ka, 8 hafta) gruplarına ayrıldı. Deney protokolünün sonun-da serum, karaciğer ve böbrek örnekleri biyokimyasal ve histopatolojik incelemeler için alındı. Femurda da histopa-tolojik değerlendirme yapıldı.Bulgular: Cerrahi olarak menopoz oluşturulan sıçan-larda östrojenin böbrek dokusunda nötrofil infiltrasyonunu ve reaktif oksijen türlerinin üretimini baskılayarak koruyu-cu etki gösterdiği, kemik kütlesinde hafif düzeyde artışa neden olduğu, ancak karaciğerin antioksidan glutatyon düzeyinde azalmaya yol açtığı belirlenmiştir. Buna karşın, östrojen uygulaması menopozda yapılan egzersiz nedeniy-le karaciğerde oluşan oksidan stresi engellemiştir. Egzer-sizle veya egzersize östrojen tedavisinin eklenmesiyle böbrek fonksiyonları önemli ölçüde etkilenmezken, kemik yapısında tek başına östrojene kıyasla daha olumlu deği-şiklikler gözlenmiştir.Sonuç: Östrojen replasmanı kemik dokusundaki olum-lu etkilerinin yanı sıra karaciğer ve böbrekte oksidan stresi azaltmakta ve özellikle karaciğerde egzersize bağlı gelişen oksidan stresi baskılayarak koruyucu etki göstermektedir.Publication Metadata only 83: phoenixin-14 ameliorates cholestatic liver injury and bileinduced acute pancreatic injury in rats(2022-05-01) KAHRAMAN, MERVE MERİÇ; YÜKSEL, MERAL; YEGEN, BERRAK; ERCAN, FERİHA; Şen L. S. , Kahraman M. M. , Mermer K. S. , Köroğlu K., Yüksel M., İmeryüz N., Ercan F., Yegen B.Background: Bile duct obstruction, which results in cholestatic liver injury, is also the major cause of acute pancreatitis. Phoenixin (PNX) was originally defined as a hypothalamic peptide associated with a wide range of physiological processes and exerts antioxidant and antiinflammatory effects. PNX is expressed in several peripheral organs including pancreas and liver. We aimed to evaluate possible therapeutic effects of PNX on hepatic and pancreatic damage induced by biliary or pancreaticobiliary duct obstruction. Methods: In male Sprague Dawley rats, bile duct ligation (BDL; n=16) or pancreaticobiliary duct ligation (PBDL; n= 16) was performed under ketamine anesthesia, while control rats (n=8) had sham-surgery. Either PNX-14 (50 µg/kg/day) or saline was subcutaneously injected immediately after surgery and in the following 2 days. On the post-operative 3rd day, hepatic and renal blood flow was measured using laser Doppler flowmeter under anesthesia and the rats were then euthanized. In the liver and pancreas samples, levels of malondialdehyde, antioxidant glutathione and myeloperoxidase activity were measured by spectrophotometry, while luminol- and lucigenin-enhanced chemiluminescence (CL) levels were measured to assess formation of reactive oxygen species (ROS). Tissue samples were stained by hematoxylin-eosin to calculate microscopic damage scores. Statistical analyses were made by one-way ANOVA. Results: Increased microscopic damage scores in the pancreas of saline-treated PBDL (p<0.001) and in the liver of saline-treated BDL group (p<0.001) were reduced by PNX14 treatment (p<0.01), but PBDL-induced hepatic damage (p<0.001) was not changed by PNX-14. Pancreatic and hepatic levels of malondialdehyde and myeloperoxidase activity and pancreatic glutathione levels were not different among the experimental groups, while hepatic glutathione level was elevated in PNX-14-treated BDL (p<0.001) and PBDL (p<0.01) groups as compared to control group. Despite a non-significant fall in renal or hepatic blood flow in saline-treated BDL rats, PBDL significantly reduced hepatic (p<0.001) and renal (p<0.01) blood flow, while PNX-14 reversed blood flow in both organs back to control levels (p<0.05). The CL levels of luminol and lucigenin were increased in both hepatic and pancreatic tissues of saline-treated BDL and PBDL groups (p<0.05-0.001), showing enhanced ROS generation. However, CL levels in both the liver and pancreas of PNX-14-treated BDL and PBDL groups were significantly reduced as compared to those measured in the liver and pancreas of respective saline-treated groups (p<0.05-0.001). Conclusion: In conclusion, cholestatic liver injury and bile-induced pancreatic injury are alleviated by PNX-14 treatment, which appears to act via its ROS scavenging activity, by replenishing hepatic antioxidant capacity and restoring impaired organ perfusion.Publication Open Access Neuropeptide W Exhibits Preventive and Therapeutic Effects on Acetic Acid-Induced Colitis via Modulation of the Cyclooxygenase Enzyme System(2023-01-01) ARABACI TAMER, SEVİL; ERCAN, FERİHA; YEGEN, BERRAK; ARABACI TAMER S., Akbulut S., Erdogan O., Cevik O., ERCAN F., YEGEN B.Background The novel peptide neuropeptide W (NPW) was originally shown to function in the control of feeding behavior and energy homeostasis. The aim of this study was to elucidate the putative preventive and therapeutic effects of NPW on colitis-associated oxidative injury and the underlying mechanisms for its action.Methods Sprague-Dawley rats in the acute colitis groups received NPW (0.5, 1 or 5 mu g/kg/day) injections prior to induction of colitis with acetic acid, while the chronic colitis groups were treated after the induction of colitis. In both acute and chronic colitis (CC) groups, treatments were continued for 5 days and the rats were decapitated at the 24th hour of the last injections and colon tissues were collected for assessments.Results NPW pretreatment given for 5 days before colitis induction, as well as treating rats with NPW during the 5-day course of CC, abolished colonic lipid peroxidation. NPW treatment prevented colitis-induced reduction in blood flow, diminished neutrophil infiltration, and pro-inflammatory cytokine responses. NPW pretreatment only at the higher dose reduced colonic edema and microscopic score and preserved colonic glutathione stores. Elevations in cyclooxygenase (COX) enzyme activity and COX-1 protein level during the acute phase of colitis as well as reduction in COX-2 were all reversed with NPW pretreatment. In contrast, NPW treatment was effective in reducing the elevated COX-2 concentration during the chronic phase.Conclusions NPW alleviates acetic acid-induced oxidative colonic injury in rats through the upregulation of colonic blood flow as well as the inhibition of COX-2 protein expression and pro-inflammatory cytokine production.Publication Open Access Rethinking large group lectures – how far in this format(2022-05-01) SEVİM, MUSTAFA; ERZİK, CAN; YEGEN, BERRAK; GÜLPINAR, MEHMET ALİ; AKTURAN S., SEVİM M., ERZİK C., YEGEN B., GÜLPINAR M. A.Objective: The aim of this study is to determine the perceptions, attitudes, and behaviour of medical students and lecturers regarding the lectures and their effects on students’ learning behaviour. Materials and Methods: This was a qualitative study including multi-methods. Researchers observed lecture ambiance and activities in two courses. Lectures were observed and slide-presentations were evaluated. Additionally, in-depth and focus group interviews were conducted. Results: Two researchers attended and observed 75 lectures. The average number of attendees was 51.21. Eighty percent of lecturers did not introduce any activities to attract attention and prepare students for the lecture. Only 12% of lectures were taught interactively. Of the evaluated 43 (69.80%) slide-presentations, sufficient association or integration was not made between clinical and basic sciences. Conclusion: This study revealed that the lectures created negative feelings and thoughts in students and lecturers, and led to undesirable attitudes and behaviour. It is essential to focus on giving interactive lectures which aim at developing reasoning, decision-making, and evaluation competencies. The most significant factors determining students’ attendance and appraisal of the lectures were related to the preparation of the lecturers, the intensity of the content, integration between basic science and clinical science, and the presentation skills.Publication Metadata only Estrogen supplementation alleviates stress-induced gastric ulcer in post-menopausal rats: the dominant role of estrogen-beta receptors(2022-05-24) KAYA, ÖZLEM TUĞÇE; YEGEN, ŞEVKET CUMHUR; ERCAN, FERİHA; YEGEN, BERRAK; YÜKSEL, MERAL; Şen L. S., Altınoluk T., İpek B. E., Akbulut S., Kaya Ö. T., Ercan F., Yüksel M., Yegen Ş. C., Yegen B.Publication Open Access Melatonin alleviates ovariectomy-induced cardiovascular inflammation in sedentary or exercised rats by upregulating SIRT1(2022-12-01) ERCAN, FERİHA; YILDIRIM, ALPER; YEGEN, BERRAK; Arabacı Tamer S., Altınoluk T., Emran M., Korkmaz S., Yüksel R. G., Baykal Z., Dur Z. S., Levent H. N., Ural M. A., Yüksel M., et al.© 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.We aimed to evaluate the impact of hormone replacement, melatonin, or exercise alone or their combination on oxidative damage and functional status of heart, brain, and aorta of ovariectomized (OVX) rats and to determine whether the signaling pathway is dependent on sirtuin-1 (SIRT1). Ovariectomized Sprague Dawley rats were orally given either a hormone replacement therapy (1 mg/kg/day,17β estradiol; HRT) or melatonin (4 mg/kg/day) or HRT + melatonin treatments or tap water, while each group was further divided into sedentary and exercise (30 min/5 days/week) groups. After the heart rate measurements and memory tests were performed, trunk blood was collected at the end of the 10th week to determine metabolic parameters in serum samples. Tissue samples of abdominal aorta, heart, and brain were taken for biochemical measurements and histopathological evaluation. Heart rates and memory performances of the OVX rats were not changed significantly by none of the applications. Melatonin treatment or its co-administration with HRT upregulated the expressions of IL-10 and SIRT1, reduced the expressions of IL-6 and TNF-α, and reduced DNA damage in the hearts and thoracic aortae of non-exercised rats. Co-administration of melatonin and HRT to exercised OVX rats reduced inflammatory response and upregulated SIRT1 expression in the aortic and cardiac tissues. The present study suggests that melatonin treatment, either alone or in combination with exercise and/or HRT, upregulates SIRT1 expression and alleviates oxidative injury and inflammation in the hearts and aortas of OVX rats. Melatonin should be considered in alleviating cardiovascular disease risk in postmenopausal women.Publication Open Access Anti-inflammatory, antioxidant and neuroprotective effects of niacin on mild traumatic brain injury in rats(2023-01-01) KOYUNCUOĞLU, TÜRKAN; AKAKIN, DİLEK; ERZİK, CAN; YÜKSEL, MERAL; YEGEN, BERRAK; Ozaydin D., Bektasoglu P. K., Koyuncuoglu T., Ozkaya S. C., Koroglu A. K., AKAKIN D., ERZİK C., YÜKSEL M., YEGEN B., Gurer B.AIM: To study the effects of niacin, a water-soluble vitamin, on inflammation, oxidative stress and apoptotic processes observed after mild traumatic brain injury (TBI). MATERIAL and METHODS: A total of 25 Wistar albino male rats were randomly divided into control (n=9), TBI + Placebo group (n=9), TBI + niacin (500 mg/kg; n=7) groups. Mild TBI was performed under anesthesia by dropping a 300 g weight from a height of 1 meter onto the skull. Behavioral tests were applied before and 24 hours after TBI. Luminol and lucigenin levels and tissue cytokine levels were measured. Histopathological damage was scored in brain tissue. RESULTS: After mild TBI, luminol and lucigenin levels were increased (p<0.001), and their levels were decreased with niacin treatment (p<0.01-p<0.001). An increased score was obtained with trauma in the tail suspension test (p<0.01), showing depressive behavior. The number of entries to arms in Y-maze test were decreased in TBI group compared to pre-traumatic values (p<0.01), while discrimination (p<0.05) and recognition indices (p<0.05) in object recognition test were decreased with trauma, but niacin treatment did not change the outcomes in behavioral tests. Levels of the anti-inflammatory cytokine IL-10 were decreased with trauma, and increased with niacin treatment (p<0.05). The histological damage score was increased with trauma (p<0.001), and decreased with niacin treatment in the cortex (p<0.05), and hippocampal dentate gyrus region (p<0.01). CONCLUSION: Niacin treatment after mild TBI inhibited trauma-induced production of reactive oxygen derivatives and elevated the anti-inflammatory IL-10 level. Niacin treatment ameliorated the histopathologically evident damage.Publication Open Access A 10-day mild treadmill exercise performed before an epileptic seizure alleviates oxidative injury in the skeletal muscle and brain tissues of the rats(2022-01-01) KAYA, ÖZLEM TUĞÇE; YEGEN, BERRAK; YÜKSEL, MERAL; YILDIRIM, ALPER; Arabaci -Tamer S., KAYA Ö. T., YÜKSEL M., YILDIRIM A., YEGEN B.© 2022 Marmara University Press, All Rights Reserved.Objective: Epileptic seizures may cause skeletal muscle injury and memory dysfunctions. The present study was aimed to investigate the possible protective effects of exercising prior to seizure on seizure-induced oxidative injury in the skeletal muscle and brain. Materials and Methods: Sprague-Dawley male rats were assigned as non-exercise (n=16) and exercise groups (n=16). Following a 3-day exercise training, exercise protocol (30 min) was performed on a treadmill for 10 days, while control rats had no exercise. On the 11th day, the epileptic seizure was induced by a single intraperitoneal injection of pentylenetetrazol (PTZ) (45 mg/kg), while the control groups were injected with saline. Passive-avoidance test was initially performed before PTZ/saline injection and repeated 72 h later for the assessment of memory function. Brain and gastrocnemius muscles were taken for histological assessments and to determine the levels of malondialdehyde (MDA) and glutathione (GSH), myeloperoxidase (MPO) activity and luminal – and lucigenin – enhanced chemiluminescence levels. Results: Exercise training alone increased the formation of reactive oxygen species and elevated the antioxidant GSH capacity of the muscle tissue in the control rats, but these effects were not observed in the muscles of the exercised rats induced with a PTZ-seizure. On the other hand, short-term exercise alone had no effect on the basal oxidative parameters of the brain tissues. Prior exercise did not alter the average seizure scores or memory performances when compared to non-exercised groups, but suppressed the PTZ-induced elevations in MDA and chemiluminescence levels as well as MPO activity in the brain. Conclusion: A 10-day mild treadmill exercise reduced the oxidative brain damage due to a single seizure-induced excitotoxicity and exerted a preconditioning effect on the skeletal muscles exposed to tonic-clonic contractions.Publication Open Access Rethinking large group lectures – how far in this format(2022-05-01) ERZİK, CAN; GÜLPINAR, MEHMET ALİ; YEGEN, BERRAK; Akturan S., Erzik C., Yegen B., Gülpınar M. A.Objective: The aim of this study is to determine the perceptions, attitudes, and behaviour of medical students and lecturers regarding the lectures and their effects on students’ learning behaviour.Materials and Methods: This was a qualitative study including multi-methods. Researchers observed lecture ambiance and activities in two courses. Lectures were observed and slide-presentations were evaluated. Additionally, in-depth and focus group interviews were conducted.Results: Two researchers attended and observed 75 lectures. The average number of attendees was 51.21. Eighty percent of lecturers did not introduce any activities to attract attention and prepare students for the lecture. Only 12% of lectures were taught interactively. Of the evaluated 43 (69.80%) slide-presentations, sufficient association or integration was not made between clinical and basic sciences.Conclusion: This study revealed that the lectures created negative feelings and thoughts in students and lecturers, and led to undesirable attitudes and behaviour. It is essential to focus on giving interactive lectures which aim at developing reasoning, decisionmaking, and evaluation competencies. The most significant factors determining students’ attendance and appraisal of the lectures were related to the preparation of the lecturers, the intensity of the content, integration between basic science and clinical science, and the presentation skills.