Browsing by Author "Erdogan, A"
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Item Surface modification of CdSeS nanocrystals for polymer hybrid solar cellsErdogan, A; Karakaya, C; Gonce, MK; Buyukcelebi, S; Yenel, E; Kara, K; Ozcivan, AN; Can, M; Kus, M; Demic, SWe 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.Item Comparison of the Protective Effects of Prostaglandin Analogues in the Ischemia and Reperfusion Model of Rabbit EyesEmre, S; Gul, M; Ates, B; Esrefoglu, M; Koc, B; Erdogan, A; Yesilada, EThis 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 Electrochemical determination of dopamine by poly (methyl orange) shape memory alloy modified carbon paste electrodeRajendrachari, S; Altas, E; Erdogan, A; Kücük, Y; Gök, MS; Khosravi, FWe 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 cm 2 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.Item Investigation of Phenolic Content in Five Different Pine Barks Species Grown in Turkey by HPLC-UV and LC-MSSeker, ME; Çelik, A; Dost, K; Erdogan, AInvestigation of phenolic content from different pine bark species grown in Turkey was performed using a reversed-phase high pressure liquid chromatography with ultraviolet (RP-HPLC-UV) method. All phenolic constituents were separated in <26 min on reversed-phase C18 column with gradient mobile phase that consists of orthophosphoric acid, methanol and acetonitrile. Detections were made on an UV detector at 280 nm and at a flow rate of 1 mL/min. Samples were prepared according to Masqueller's conventional sample preparation method with slight modifications. To avoid the reduction in extraction efficiency the sample preparation step was carried out under argon atmosphere. The linearity of the method was between 0.9994 and 0.9999. The detection limits for the five phenolic constituents ranged from 0122 to 0.324 mg/L. Catechin and taxifolin were found in all pine barks at a concentration of 0.065 +/- 0.002-1.454 +/- 0.004 and 0.015 +/- 0.001-23.164 +/- 0.322 mg/g, respectively. Epicatechin was determined in four pine barks between 0.027 +/- 0.001 and 0.076 +/- 0.002 mg/g, ferulic acid in two pine barks between 0.010 +/- 0.001 and 0.022 +/- 0.001 mg/g and epicatechin gallate in only one of the pine barks at 0.025 +/- 0.001 mg/g. Finally, the total amount of phenolic compounds and antioxidant capacities of the pine barks were found to be very high.Item A New Network for the Advancement of Marine Biotechnology in Europe and BeyondRotter, A; Bacu, A; Barbier, M; Bertoni, F; Bones, A; Cancela, ML; Carlsson, J; Carvalho, MF; Ceglowska, M; Dalay, MC; Dailianis, T; Deniz, I; Drakulovi, D; Dubnika, A; Einarsson, H; Erdogan, A; Eroldogan, OT; Ezra, D; Fazi, S; FitzGerald, RJ; Gargan, LM; Gaudêncio, SP; DeNardis, NI; Joksimovic, D; Katarzyte, M; Kotta, J; Mandalakis, M; Matijosyte, I; Mazur-Marzec, H; Massa-Gallucci, A; Mohamed, M; Nielsen, SL; Novoveská, L; Overlinge, D; Portman, ME; Pyrc, K; Rebours, C; Reinsch, T; Reyes, F; Rinkevich, B; Robbens, J; Rudovica, V; Sabotic, J; Safarik, I; Talve, S; Tasdemir, D; Schneider, XT; Thomas, OP; Torunska-Sitarz, A; Varese, GC; Vasquez, MIMarine organisms produce a vast diversity of metabolites with biological activities useful for humans, e.g., cytotoxic, antioxidant, anti-microbial, insecticidal, herbicidal, anticancer, pro-osteogenic and pro-regenerative, analgesic, anti-inflammatory, anticoagulant, cholesterol-lowering, nutritional, photoprotective, horticultural or other beneficial properties. These metabolites could help satisfy the increasing demand for alternative sources of nutraceuticals, pharmaceuticals, cosmeceuticals, food, feed, and novel bio-based products. In addition, marine biomass itself can serve as the source material for the production of various bulk commodities (e.g., biofuels, bioplastics, biomaterials). The sustainable exploitation of marine bio-resources and the development of biomolecules and polymers are also known as the growing field of marine biotechnology. Up to now, over 35,000 natural products have been characterized from marine organisms, but many more are yet to be uncovered, as the vast diversity of biota in the marine systems remains largely unexplored. Since marine biotechnology is still in its infancy, there is a need to create effective, operational, inclusive, sustainable, transnational and transdisciplinary networks with a serious and ambitious commitment for knowledge transfer, training provision, dissemination of best practices and identification of the emerging technological trends through science communication activities. A collaborative (net)work is today compelling to provide innovative solutions and products that can be commercialized to contribute to the circular bioeconomy. This perspective article highlights the importance of establishing such collaborative frameworks using the example of Ocean4Biotech, an Action within the European Cooperation in Science and Technology (COST) that connects all and any stakeholders with an interest in marine biotechnology in Europe and beyond.Item The Essentials of Marine BiotechnologyRotter, A; Barbier, M; Bertoni, F; Bones, AM; Cancela, ML; Carlsson, J; Carvalho, MF; Ceglowska, M; Chirivella-Martorell, J; Dalay, MC; Cueto, M; Dailianis, T; Deniz, I; Díaz-Marrero, AR; Drakulovic, D; Dubnika, A; Edwards, C; Einarsson, H; Erdogan, A; Eroldogan, OT; Ezra, D; Fazi, S; FitzGerald, RJ; Gargan, LM; Gaudêncio, SP; Udovic, MG; DeNardis, NI; Jónsdóttir, R; Katarzyte, M; Klun, K; Kotta, J; Ktari, L; Ljubesic, Z; Bilela, LL; Mandalakis, M; Massa-Gallucci, A; Matijosyté, I; Mazur-Marzec, H; Mehiri, M; Nielsen, SL; Novoveská, L; Overlinge, D; Perale, G; Ramasamy, P; Rebours, C; Reinsch, T; Reyes, F; Rinkevich, B; Robbens, J; Röttinger, E; Rudovica, V; Sabotid, J; Safarik, I; Talve, S; Tasdemir, D; Schneider, XT; Thomas, OP; Torunska-Sitarz, A; Varese, GC; Vasquez, MCoastal countries have traditionally relied on the existing marine resources (e.g., fishing, food, transport, recreation, and tourism) as well as tried to support new economic endeavors (ocean energy, desalination for water supply, and seabed mining). Modern societies and lifestyle resulted in an increased demand for dietary diversity, better health and well-being, new biomedicines, natural cosmeceuticals, environmental conservation, and sustainable energy sources. These societal needs stimulated the interest of researchers on the diverse and underexplored marine environments as promising and sustainable sources of biomolecules and biomass, and they are addressed by the emerging field of marine (blue) biotechnology. Blue biotechnology provides opportunities for a wide range of initiatives of commercial interest for the pharmaceutical, biomedical, cosmetic, nutraceutical, food, feed, agricultural, and related industries. This article synthesizes the essence, opportunities, responsibilities, and challenges encountered in marine biotechnology and outlines the attainment and valorization of directly derived or bio-inspired products from marine organisms. First, the concept of bioeconomy is introduced. Then, the diversity of marine bioresources including an overview of the most prominent marine organisms and their potential for biotechnological uses are described. This is followed by introducing methodologies for exploration of these resources and the main use case scenarios in energy, food and feed, agronomy, bioremediation and climate change, cosmeceuticals, bio-inspired materials, healthcare, and well-being sectors. The key aspects in the fields of legislation and funding are provided, with the emphasis on the importance of communication and stakeholder engagement at all levels of biotechnology development. Finally, vital overarching concepts, such as the quadruple helix and Responsible Research and Innovation principle are highlighted as important to follow within the marine biotechnology field. The authors of this review are collaborating under the European Commission-funded Cooperation in Science and Technology (COST) Action Ocean4Biotech - European transdisciplinary networking platform for marine biotechnology and focus the study on the European state of affairs.Item Marine Anticancer Agents: An Overview with a Particular Focus on Their Chemical ClassesBarreca, M; Spane, V; Montalbano, A; Cueto, M; Marrero, ARD; Deniz, I; Erdogan, A; Bilela, LL; Moulin, C; Taffin-de-Givenchy, E; Spriano, F; Perale, G; Mehiri, M; Rotter, A; Thomas, OP; Barraja, P; Gaudencio, SP; Bertoni, FThe marine environment is a rich source of biologically active molecules for the treatment of human diseases, especially cancer. The adaptation to unique environmental conditions led marine organisms to evolve different pathways than their terrestrial counterparts, thus producing unique chemicals with a broad diversity and complexity. So far, more than 36,000 compounds have been isolated from marine micro- and macro-organisms including but not limited to fungi, bacteria, microalgae, macroalgae, sponges, corals, mollusks and tunicates, with hundreds of new marine natural products (MNPs) being discovered every year. Marine-based pharmaceuticals have started to impact modern pharmacology and different anti-cancer drugs derived from marine compounds have been approved for clinical use, such as: cytarabine, vidarabine, nelarabine (prodrug of ara-G), fludarabine phosphate (pro-drug of ara-A), trabectedin, eribulin mesylate, brentuximab vedotin, polatuzumab vedotin, enfortumab vedotin, belantamab mafodotin, plitidepsin, and lurbinectedin. This review focuses on the bioactive molecules derived from the marine environment with anticancer activity, discussing their families, origin, structural features and therapeutic use.Item A multicentre, multinational study of clinical characteristics and prognosis of hepatocellular carcinomaDirican, A; Uncu, D; Sekacheva, M; Artac, M; Aladashvil, A; Erdogan, A; Kaplan, M; Alacacioglu, A; Boukovinas, I; Turhal, NBackground: 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 (Turkiye, 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.Item Programmed cell death ligand-1 expression in gastroentero-pancreatic neuroendocrine tumorsOktay, E; Yalcin, GD; Ekmekci, S; Kahraman, DS; Yalcin, A; Degirmenci, M; Dirican, A; Altin, Z; Ozdemir, O; Surmeli, Z; Diniz, G; Ayhan, S; Bulut, G; Erdogan, A; Uslu, RPurpose: 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-LI and mRNA was evaluated with IHC. Results: The expression of PD-L1 was significantly associated with the high-grade classification (p=0.012). PD-LI 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.Item Push and Pull Factors of Why Medical Students Want to Leave Turkiye: A Countrywide Multicenter StudyEser, E; Cil, E; Sen Gundogan, NE; Col, M; Ozturk, ENY; Thomas, DT; Sunter, AT; Arslan, HN; Citil, R; Onder, Y; Picakciefe, M; Dede, B; Demirel, C; Aydin, N; Caglayan, C; Aker, AA; Borlu, A; Durmus, H; Can, G; Siddikoglu, E; Sumer, EH; Uygun, T; Alkoy, S; Aycan, KA; Koruk, I; Kuzan, R; Demir, LS; Hacilar, E; Sari, H; Kilinc, Z; Onal, O; Dogan, E; Emek, M; Terzioglu, R; Yapici, G; Erdal, D; Eser, S; Akman, EA; Kosan, Z; Yilmaz, S; Ayoglu, FN; Acikgoz, B; Musal, B; Suner, AF; Erdogan, A; Cilburunoglu, I; Saygun, M; Daymaz, D; Arslantas, D; Onsuz, MF; Beyhun, NE; Ustundag, MG; Ekuklu, G; Tas, FO; Abacigil, F; Oncu, S; Hidiroglu, S; Ozaydin, AN; Pirincci, E; Bulut, I; Tozun, M; Eskiocak, M; Gunel, P; Torun, SD; Yavuz, M; Hasde, M; Camur, D; Gunes, G; Kurt, B; Baysoy, NG; Bakirci, N; Demir, F; Catak, B; Ozyurda, F; Turan, MPhenomenon: 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 Turkiye, 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 Turkiye 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 Turkiye in 2022. Besides participants' migration decision, we evaluated the push and pull factors related to working, social environment and lifestyle in Turkiye 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 Turkiye. Improving working conditions in the country and increasing the quality of medical faculties seem vital in preventing the migration of physicians.Item Push and Pull Factors of Why Medical Students Want to Leave Türkiye: A Countrywide Multicenter StudyEser, E; Cil, E; Sen Gundogan, NE; Col, M; Ozturk, ENY; Thomas, DT; Sunter, AT; Arslan, HN; Citil, R; Onder, Y; Picakciefe, M; Dede, B; Demirel, C; Aydin, N; Caglayan, C; Aker, AA; Borlu, A; Durmus, H; Can, G; Siddikoglu, E; Sumer, EH; Uygun, T; Alkoy, S; Aycan, KA; Koruk, I; Kuzan, R; Demir, LS; Hacilar, E; Sari, H; Kilinc, Z; Onal, O; Dogan, E; Emek, M; Terzioglu, R; Yapici, G; Erdal, D; Eser, S; Akman, EA; Kosan, Z; Yilmaz, S; Ayoglu, FN; Acikgoz, B; Musal, B; Suner, AF; Erdogan, A; Cilburunoglu, I; Saygun, M; Daymaz, D; Arslantas, D; Onsuz, MF; Beyhun, NE; Ustundag, MG; Ekuklu, G; Tas, FO; Abacigil, F; Oncu, S; Hidiroglu, S; Ozaydin, AN; Pirincci, E; Bulut, I; Tozun, M; Eskiocak, M; Gunel, P; Torun, SD; Yavuz, M; Hasde, M; Camur, D; Gunes, G; Kurt, B; Baysoy, NG; Bakirci, N; Demir, F; Catak, B; Ozyurda, F; Turan, MPhenomenon: 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 T & uuml;rkiye, 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 T & uuml;rkiye 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 T & uuml;rkiye in 2022. Besides participants' migration decision, we evaluated the push and pull factors related to working, social environment and lifestyle in T & uuml;rkiye 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 T & uuml;rkiye. Improving working conditions in the country and increasing the quality of medical faculties seem vital in preventing the migration of physicians.Item Investigation of Pycnogenol Content in Five Different Pine Barks Species Grown in Turkey by HPLC-UV and LC-MS (vol 59, pg 491, 2021)Seker, ME; Çelik, A; Dost, K; Erdogan, A