Browsing by Author "Erdogan A."
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Item Comparison of the protective effects of prostaglandin analogues in the ischemia and reperfusion model of rabbit eyes(2009) Emre S.; Gul M.; Ates B.; Esrefoglu M.; Koc B.; Erdogan A.; Yesilada E.This study was planned to investigate the neuroprotective potentials of three commercially available prostaglandin analogues (PGA), in the ischemia and reperfusion model (I/R). Thirty New Zealand rabbits were divided into 5 groups and except for the control group (non-ischemic, non-treated), 0.9% NaCl, bimatoprost, latanoprost, or travoprost were applied to both eyes of animals of the respective groups for 1 week. At the end of treatment, ischemia was induced in both eyes of the 4 treatment groups by anterior chamber irrigation of the animals for 60 min. Following 24 h reperfusion, the animals were sacrified. Enucleated eyes and retinal tissues were investigated by light microscopy, electron microscopy, immunohistochemicstry for retinal histopathology, intracellular and apoptotic cells and by retinal morphometry. Vitreous samples were biochemically investigated for probable role of reactive oxygen species, by measuring xanthine oxidase (XO) activity. Analysis of morphometric measurements and vitreous XO activity revealed significant differences between the PGA-treated groups and the NaCl-treated group (P<0.05). Similarly, apoptotic cell counts in different retinal layers showed that PGA-treated groups had fewer apoptotic cells in all retinal layers than the NaCl-treated ischemic group (P<0.05). PGA may have high protective potential for different retinal layers and cells. Biochemical analysis of vitreous showed that all PGAs decreased vitreous XO activity significantly compared to the NaCl-treated group (P<0.05). However we could not find any statistically significant differences among the analogues. PGAs may reduce the injury induced by I/R, through the inhibition of XO activity, and it seems that their effects are elicited through numerous pathways.Item Surface modification of CdSeS nanocrystals for polymer hybrid solar cells(Royal Society of Chemistry, 2016) Erdogan A.; Karakaya C.; Gonce M.K.; Buyukcelebi S.; Yenel E.; Kara K.; Ozcivan A.N.; Can M.; Kus M.; Demic S.We report the synthesis of fluorene-carbazole derivatives as capping agents for CdSeS nanocrystals and present their performance in polymer hybrid solar cells. CdSeS nanocrystals and different ligands consisting of fluorene and carbazole units were synthesized and characterized. Both oleic acid and pyridine capped CdSeS nanocrystals were used as reference materials in polymer hybrid solar cells. We observed that our synthesized materials show better efficiencies depending on their structures. In comparison with the reference cells consisting of pyridine capped CdSeS nanocrystals, ligand capped CdSeS shows better efficiency due to electron withdrawing and accepting groups in its structure. The reason behind the superiority of our ligands compared to the reference pyridine is the donor and/or acceptor based compatibility of the combined structures and effective surface modification as well. © 2016 The Royal Society of Chemistry.Item Programmed cell death ligand-1 expression in gastroenteropancreatic neuroendocrine tumors(Zerbinis Publications, 2019) Oktay E.; Yalcin G.D.; Ekmekci S.; Kahraman D.S.; Yalcin A.; Degirmenci M.; Dirican A.; Altin Z.; Ozdemir O.; Surmeli Z.; Diniz G.; Ayhan S.; Bulut G.; Erdogan A.; Uslu R.Purpose: Gastroenteropancreatic tumors (GEPNETs) is a heterogeneous disease with variable clinical course. While promising therapeutic options exist for other adult cancers, there are no new molecular-based treatments developed for GEPNETs. One of the main targets of cancer immunotherapy is the Programmed Cell Death Ligand-1 (PD-L1) pathway. Our purpose was to investigate the profile of PD-L1 expression in different organs of GEPNETs and compare the conventional immunohistochemistry (IHC) with the RNA expression analysis via real time polymerase chain reaction (RT-PCR) in order to determine which patients might be appropriate for immune check point-targeted therapy. Methods: A total of 59 surgically or endoscopically resected GEPNET tissues were retrospectively collected. The expression of PD-L1 and mRNA was evaluated with IHC. Results: The expression of PD-L1 was significantly associated with the high-grade classification (p=0.012). PD-L1 mRNA expression in tumor samples appeared to be higher compared to the corresponding normal tissues. In appendix, stomach and small intestine, the expression of PD-L1 mRNA was higher in the tumor tissues compared to the respective controls. In pancreas and colon, control tissues tend to have a higher PD-L1 mRNA expression compared to tumor tissues. PD-L1 mRNA expression was higher in GEP carcinomas (p=0.0031). Conclusion: RT-PCR was found to be more sensitive in detecting PD-L1 expression than conventional IHC. This study may provide an important starting point and useful background information for future research about immunotherapy for appendix, stomach and small intestine neuroendocrine carcinomas. © 2019 Zerbinis Publications. All rights reserved.Item A multicentre, multinational study of clinical characteristics and prognosis of hepatocellular carcinoma; [Étude multicentrique et multinationale des caractéristiques cliniques et du pronostic du carcinome hépatocellulaire](World Health Organization, 2023) Dirican A.; Uncu D.; Sekacheva M.; Artaç M.; Aladashvil A.; Erdogan A.; Kaplan M.; Alacacıoğlu A.; Boukovinas I.; Turhal N.Background: Hepatocellular carcinoma (HCC) is a significant health problem, and the associated mortality rate is increasing. Aim: We aimed to determine the clinical characteristics and prognosis for HCC in member countries of the OncoBridge Study Group. Methods: We recruited 630 patients diagnosed with HCC between 2013 and 2019 from 4 countries (Türkiye, Russia, Georgia, and Greece). Univariate and multivariate analyses were conducted to investigate clinical and laboratory prognostic factors. Receiver operating characteristic (ROC) analysis was used to determine the prognostic value of the neutrophil to lymphocyte ratio (NLR) and alpha-fetoprotein (AFP) value. Results: The 3 most common etiological factors were hepatitis B infection (39.7%), hepatitis C virus infection (17.0%) and non-alcoholic fatty liver disease (9.0%). Median overall survival for the whole group was 25 [95% confidence interval (CI): 15.7–34.2] months. Cut-off values for AFP and NLR were accepted as 200 ng/mL and 3.45, respectively. The area under the ROC curve values for AFP, NLR and NLR+AFP were 0.625 (95% CI: 0.547–0.704), 0.589 (95% CI: 0.512–0.667) and 0.657 (95% CI: 0.583–0.731). From the multivariate analysis, advanced tumour size, lymph node involvement and metastasis (TNM) stage, presence of cirrhosis, high AFP, and high NLR values were associated with poor survival. Conclusion: AFP, NLR, advanced TNM, and presence of cirrhosis may predict prognosis in patients with HCC. Studies involving more countries are needed to corroborate these findings. © Authors 2023; Licensee: World Health Organization.Item Electrochemical determination of dopamine by poly (methyl orange) shape memory alloy modified carbon paste electrode(Elsevier B.V., 2024) Rajendrachari S.; Altaş E.; Erdogan A.; Küçük Y.; Gök M.S.; Khosravi F.We have successfully prepared 50Ni-30Ti-20Hf shape memory alloy powders using a high-energy planetary ball mill for 20 h by wet milling. The fabricated shape memory alloy powders were characterized by X-ray diffraction (XRD), and scanning electron microscope (SEM) to investigate the phases present and the morphology of the powders respectively. The use of 50Ni-30Ti-20Hf (nitinol) shape memory alloy powders as electro-catalytic materials is a unique and new idea. We are the first researchers to use nitinol powders as dopamine (DA) electrochemical sensors. For better electrochemical oxidation and higher current response of DA, we have electro-polymerized the surface of nitinol-modified carbon paste electrode (MCPE) with methyl orange (MO). Using poly(MO)-NiTiHf-MCPE, we have determined the DA using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) respectively. The calculated active surface area for BCPE, NiTiHf-MCPE, and the poly(MO)-NiTiHf-MCPE were found to be 0.044, 0.089, and 0.098 cm2 respectively. The electro-polymerized nitinol MCPE not only increased the surface area but also increased the electron transfer kinetics. Our results confirmed the participation of 2 electrons and 2 protons in the electrochemical redox reaction. © 2024 Elsevier B.V.Item Push and Pull Factors of Why Medical Students Want to Leave Türkiye: A Countrywide Multicenter Study(Routledge, 2024) Eser E.; Cil E.; Sen Gundogan N.E.; Col M.; Yildirim Ozturk E.N.; Thomas D.T.; Sunter A.T.; Arslan H.N.; Citil R.; Onder Y.; Picakciefe M.; Dede B.; Demirel C.; Aydin N.; Caglayan C.; Aker A.A.; Borlu A.; Durmus H.; Can G.; Siddikoglu E.; Sumer E.H.; Uygun T.; Alkoy S.; Aktas Aycan K.; Koruk İ.; Kuzan R.; Demir L.S.; Hacilar E.; Sari H.; Kilinc Z.; Onal O.; Dogan E.; Emek M.; Terzioglu R.; Yapici G.; Erdal D.; Eser S.; Ayhan Akman E.; Kosan Z.; Yilmaz S.; Ayoglu F.N.; Acikgoz B.; Musal B.; Suner A.F.; Erdogan A.; Cilburunoglu İ.; Saygun M.; Daymaz D.; Arslantas D.; Onsuz M.F.; Beyhun N.E.; Ustundag M.G.; Ekuklu G.; Ozder Tas F.; Abacigil F.; Oncu S.; Hıdıroğlu S.; Ozaydin A.N.; Pirincci E.; Bulut I.; Tozun M.; Eskiocak M.; Gunel P.; Torun S.D.; Yavuz M.; Hasde M.; Camur D.; Gunes G.; Kurt B.; Guler Baysoy N.; Bakirci N.; Demir F.; Catak B.; Ozyurda F.; Turan M.Phenomenon: Physician immigration from other countries is increasing as developed countries continue to be desirable destinations for physicians; however, the determinants of Turkish physicians’ migration decisions are still unclear. Despite its wide coverage in the media and among physicians in Türkiye, and being the subject of much debate, there is insufficient data to justify this attention. With this study, we aimed to investigate the tendency of senior medical students in Türkiye to pursue their professional careers abroad and its related factors. Approach: This cross-sectional study involved 9881 senior medical students from 39 different medical schools in Türkiye in 2022. Besides participants’ migration decision, we evaluated the push and pull factors related to working, social environment and lifestyle in Türkiye and abroad, medical school education inadequacy, and personal insufficiencies, as well as the socioeconomic variables that may affect the decision to migrate abroad. The analyses were carried out with a participation rate of at least 50%. Findings: Of the medical students, 70.7% had emigration intentions. Approximately 60% of those want to stay abroad permanently, and 61.5% of them took initiatives such as learning a foreign language abroad (54.5%) and taking relevant exams (18.9%). Those who wanted to work in the field of Research & Development were 1.37 (95% CI: 1.22–1.54) times more likely to emigrate. The push factor that was related to emigration intention was the “working conditions in the country” (OR: 1.89, 95% CI: 1.56–2.28) whereas the “social environment/lifestyle abroad” was the mere pull factor for the tendency of emigration (OR: 1.73, 95% CI: 1.45–2.06). In addition, the quality problem in medical schools also had a significant impact on students’ decisions (OR: 2.20, 95% CI: 1.83–2.65). Insights: Although the percentage of those who want to emigrate “definitely” was at the same level as in the other developing countries, the tendency to migrate “permanently” was higher in Türkiye. Improving working conditions in the country and increasing the quality of medical faculties seem vital in preventing the migration of physicians. © 2023 Taylor & Francis Group, LLC.