Person: AKSU, MEHMET BURAK
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AKSU
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MEHMET BURAK
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Publication Open Access A novel approach for the fabrication of 3D-printed dental membrane scaffolds including antimicrobial pomegranate extract.(2023-02-22) AKSU, MEHMET BURAK; Karabulut H., Ulag S., Dalbayrak B., Arisan E. D., Taskin T., Guncu M. M., Aksu B., Valanezhad A., Gunduz O.In this study, a dental membrane scaffold was fabricated using a 3D printing technique, and the antimicrobial effect of pomegranate seed and peel extract were investigated. For the production of the dental membrane scaffold, a combination of polyvinyl alcohol, starch, and pomegranate seed and peel extracts was used. The aim of the scaffold was to cover the damaged area and aid in the healing process. This can be achieved due to the high antimicrobial and antioxidant content of pomegranate seed and peel extracts (PPE: PSE). Moreover, the addition of starch and PPE: PSE improved the biocompatibility of the scaffold, and their biocompatibility was tested using human gingival fibroblast (HGF) cells. The addition of PPE: PSE into the scaffolds resulted in a significant antimicrobial effect on S. aureus and E. faecalis bacteria. Moreover, different concentrations of starch (1%, 2%, 3% w/v) and pomegranate peel and seed extract (3%, 5%, 7%, 9%, and 11% PE v/v) were analyzed to obtain the ideal dental membrane structure. The optimum starch concentration was chosen as 2% w/v due to it giving the scaffold the highest mechanical tensile strength (23.8607 ± 4.0796 MPa). The pore sizes of each scaffold were studied by SEM analysis, and pore sizes were arranged between 155.86 and 280.96 µm without any plugging problems. Pomegranate seed and peel extracts were obtained by applying the standard extraction method. High-performance liquid chromatography was performed using the diode-array detection (HPLC-DAD) technique to analyze the phenolic content of the pomegranate seed and peel extracts. Two phenolic components of the pomegranate seed and peel extracts were investigated in the following amounts: fumaric acid (17.56 µg analyte/mg extract) and quinic acid (18.79 µg analyte/mg extract) in pomegranate seed extract and fumaric acid (26.95 µg analyte/mg extract) and quinic acid (33.79 µg analyte/mg extract) in pomegranate peel extract.Publication Open Access FIP teşhisi konmuş kedilerden elde edilen periferal kan mononükleer hücreler ile kedi overinden elde edilen mezenkimal kök hücrenin immünolojik araştırılması(2023-05-25) AKSU, MEHMET BURAK; AKKOÇ, TUNÇ; Güven N., Erhan M. N., Karayusuf K., Doğanay K., Kılıç S., Tunca Z., Aksu M. B., Akkoç T.Giriş ve Amaç: Coronavirüsler hem insanlarda hem de hayvanlarda hafiften son derece şiddetli enfeksiyonlara kadar değişkenlik göstermektedir. Coronaviruslar çoğunlukla gastroentestinal ve solunum sistemi enfeksiyonlarına neden olurken bazıları ensefaliti ve hepatite neden olmaktadır. Kedilerin Enfeksiyöz Peritonitisi (FIP) ise kedi coronavirüslerinin (FCoV) neden olduğu bir enfeksiyondur. Çalışmamızda ise kedi ovaryum kaynaklı mezenkimal kök hücrelerin (O-MKH), FIP teşhisi konmuş kedilerden elde edilen periferal kan mononükleer hücrelere (PKMH) etkisinin in vitro ortamda araştırılıp değerlendirilmesi amaçlanmaktadır. Gereç ve Yöntem: Projemizde veteriner kliniğinde FIP tanısı konulmuş 5-13 yaşlarındaki kediler çalışmaya dahil edilecektir. Bu süreçte veteriner kliniğine gelen hastalardan FIP pozitif çıkan kedilerden hasta sahiplerinden alınan onam sonrasında 5cc periferal kan örneği alınacak ve Marmara Üniversitesi Tıp Fakültesi immünoloji anabilim dalında PKMH izole edilecektir. Ayrıca, kedi ovaryumlardan MKH izolasyonu gerçekleştirilecektir. İzole edilen PKMH ile O-MKH\"ların (+/-) ko-kültür işlemleri gerçekleştirilecektir. 5 günlük kültür işleminden sonra O-MKH\"nin FIP hasta PMKH\"larının canlılıkları üzerindeki etkileri akım sitometri yöntemi ile analiz edilecektir. Gerekli etik ve kurum izinleri alınmıştır. Bulgular: Yapılan ko-kültür çalışması sonrasında akım sitometri yöntemi ile PKMH’lerin canlılıklarındaki değişimler kıyaslanmıştır. Yapılan analizler sonucunda FIP kedilerin PKMH’ları MKH’nın olmadığı durumlarda canlılık oranı 55.6 (±5.2) iken MKH varlığında canlılıklarının 70.13 (±2.1)’e yükseldiği görülmüştür. Buna ek olarak, apoptoz geçiren PKMH’ların oranı MKH yokluğunda 34.7 (±4.4) iken MKH varlığında 12.7’e (±1.8) düştüğü gözlenmiştir. Hastalardaki PKMH’ların sağlıklı kedilerin durumları ile kıyaslandığında ise FIP hastası PKMH’ların canlılıkları MKH varlığında sağlıklı kedilerin PKMH’ların canlılık seviyesine yükseldiği görülmüştür. Sonuç: FIP hastalığına sahip olan kedilerin PKMH’larındaki canlılık oranının sağlıklı kediye kıyasla canlılık oranının beklendiği gibi daha düşük olduğu görülmüştür. Yine de MKH’nın varlığında FIP hastası kedilerin PKMH’larındaki canlılık seviyesinin sağlıklı kedilerin PKMH’lerin canlılık oranına yükseldiği görülmüştür. Ayrıca, MKH’ların apoptoz geçiren PKMH’ları FIP hastası kedilerde düşürdüğü gözlenmiştir. Elde edilen bu veriler çerçevesinde MKH’ların FIP hastalarında olumlu etkisi olduğu gözlenmektedir.Publication Open Access Fabrication of gentamicin sulfate-loaded 3d-printed polyvinyl alcohol/sodium alginate/gelatin-methacryloyl hybrid scaffolds for skin tissue replacement(2023-01-01) ULAĞ, SONGÜL; ŞAHİN, ALİ; AKSU, MEHMET BURAK; GÜNDÜZ, OĞUZHAN; Izgordu M. S., Ayran M., ULAĞ S., Yildirim R., Bulut B., ŞAHİN A., Guncu M. M., AKSU M. B., GÜNDÜZ O.3D-printed scaffolds can better mimic the function of human skin, both biologically and mechanically. Within the scope of this study, the effect of the addition of different amounts (10, 15, 20 mg) of gentamicin sulfate (GS) to a 10 mL solution of natural and synthetic polymers is investigated. Sodium alginate (SA), gelatin-methacryloyl (GelMA), and polyvinyl alcohol (PVA) are chosen as bioactive materials. The surface morphology and pore structures are visualized by scanning electron microscopy (SEM). According to the results, it is observed that the pore sizes of all scaffolds are smaller than 270 µm, the lowest value (130 µm) is obtained in the scaffold loaded with 15 mg GS, and it also has the highest tensile strength value (12.5 ± 7.6 MPa). Similarly, it is observed that the tensile strength (9.7 ± 4.5 MPa) is high in scaffold loaded with 20 mg GS. The biocompatibility test is performed with fibroblast cells, and the results show that the scaffolds are biocompatible with cells. The antibacterial test is carried out against the S.aureous and E. coli and the results indicate that all GS-loaded scaffolds demonstrate antibacterial activity.Publication Open Access Phenolic compounds affect production of pyocyanin, swarming motility and biofilm formation of Pseudomonas aeruginosa(WOLTERS KLUWER MEDKNOW PUBLICATIONS, 2016-08) KARAHASAN, AYŞEGÜL; Ugurlu, Aylin; Yagci, Aysegul Karahasan; Ulusoy, Seyhan; Aksu, Burak; Bosgelmez-Tinaz, GulgunObjective: To investigate the effects of plant-derived phenolic compounds (i.e. caffeic acid, cinnamic acid, ferulic acid and vanillic acid) on the production of quorum sensing regulated virulence factors such as pyocyanin, biofilm formation and swarming motility of Pseudomonas aeruginosa (P. aeruginosa) isolates. Methods: Fourteen clinical P. aeruginosa isolates obtained from urine samples and P. aeruginosa PA01 strain were included in the study. The antibacterial effects of phenolic compounds were screened by well diffusion assay. Pyocyanin and biofilm activity were measured from culture supernatants and the absorbance values were measured using a spectrophotometer. Swarming plates supplemented with phenolic acids were point inoculated with P. aeruginosa strains and the ability to swarm was determined by measuring the distance of swarming from the central inoculation site. Results: Tested phenolic compounds reduced the production of pyocyanin and biofilm formation without affecting growth compared to untreated cultures. Moreover, these compounds blocked about 50% of biofilm production and swarming motility in P. aeruginosa isolates. Conclusions: We may suggest that if swarming and consecutive biofilm formation could be inhibited by the natural products as shown in our study, the bacteria could not attach to the surfaces and produce chronic infections. Antimicrobials and natural products could be combined and the dosage of antimicrobials could be reduced to overcome antimicrobial resistance and drug side effects.Publication Open Access Canine adipose tissue stem cells induced with toll-like receptor agonists exhibit antibacterial activity against multi drug resistant pathogens(2023-03-01) AKSU, MEHMET BURAK; AKKOÇ, TUNÇ; AKSU M. B., Yanilmaz O., AKKOÇ T.Infections caused by antibiotic-resistant pathogens pose a major threat worldwide. There is an urgent need to develop effective strategies to solve this problem. The antibacterial activity of adult mesenchymal stem cells (MSCs) has recently been determined against various bacterial isolates. New approaches, such as Toll-like receptor activation, were used to enhance their antibacterial potency. This study examines the antibacterial activity of TLR agonist (TLR2/TLR1 and/or TLR2/TLR6) activated adipose-derived canine MSCs (AD-MSCs) on multidrug resistant isolates including Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, and Pseudomonas aeruginosa regarding bacterial growth, and minimum inhibitory concentration (MIC) determination. Effects on bacterial morphology were assessed by electron microscopy. Our results showed that the AD-MSCs conditioned medium primed with different TLR agonists inhibited the growth of E. coli and S. aureus, but it had a decreased effect on E. faecalis and P. aeruginosa. Despite this, AD-MSCs conditioned medium prepared with the combination of TLR agonists exhibited antibacterial activity against all isolates. These findings were in parallel with MIC levels of conditioned media. We conclude that adipose-derived canine MSCs primed with TLR agonists (TLR2/TLR1 and TLR2/TLR6 combination) possess antimicrobial activity against multi-drug resistant isolates of E. coli, S. aureus, E. faecalis and P. aeruginosa. Further studies for testing in in vivo models are being planned to assess the potential application of AD-MSCs as an adjunct treatment modality for multi drug resistant infections.Publication Open Access Atypical Cell'' Parameter in Automated Urine Analysis for the Diagnosis of Bladder Cancer: A Retrospective Pilot Study(GALENOS YAYINCILIK, 2020-04-01) FİLİNTE, DENİZ; Tinay, Ilker; Sahin, Bahadir; Saracoglu, Sertac; Yanilmaz, Ozgur; Aksu, Mehmet Burak; Ayas, Ramazan; Filinte, Deniz; Cam, Haydar Kamil; Ilki, ArzuObjective: To evaluate the application of an automated urine analyzer (AUA) for the diagnosis of bladder cancer (BC) Materials and Methods: A retrospective data analysis of 2365 urine specimens from the department of urology has been performed and matched with those patients, who have undergone cystoscopic evaluation or surgical treatment for different urological pathologies during 2018. After matching, clinical records of the patients has been further evaluated in order to select patients with recent or previous BC diagnosis. To assess the diagnostic efficacy of AUA, patients were divided into five groups according to the patient history of BC and healthy controls. Results: A total of 106 patients are included in this study and the majority (69.8%) of the patients are follow-up patients with previous diagnosis and treatment of non-muscle invasive BC (NMIBC). For patients with low-risk NMIBC (n=27), the sensitivity and specificity were calculated as 75% and 100%. For patients with high-risk NMIBC (n=47), who were previously treated with intravesical BCG, the sensitivity and specificity were calculated as 54.5% and 83.3%. All patients in radical cystectomy group (n=7) with muscle invasive BC had positive urine analyses results for atypical cells. And none of the patients in the control group (n=8) had positive AUA results and cystoscopic evaluation also did not show any bladder mass suspicious for BC. Conclusion: The results of this retrospective pilot study showed acceptable sensitivity and specificity rates of the fluorescence flow cytometry based AUA and the results of the low-risk group are especially valuable regarding its potential use to decide on performing a follow-up cystoscopy or not. A prospective study is currently on progress to validate the findings of the current study.Publication Open Access Performance of “RESIST-3 O.K.N. K-SeT” immunochromatographic assay for the detection of OXA-48 like, KPC, and NDM carbapenemases in Klebsiella pneumoniae in Turkey(2018-10) ALTINKANAT GELMEZ, GÜLŞEN; Sağıroğlu, Pınar; Hasdemir, Ufuk; Altınkanat Gelmez, Gülşen; Aksu, Burak; Karatuna, Onur; Söyletir, GünerPublication Open Access The failure on the effectiveness of formalin on cadaver disinfection and alternative methods(2023-01-01) AKSU, MEHMET BURAK; ÖZKAN, MAZHAR; ŞEHİRLİ, ÜMİT SÜLEYMAN; Yanilmaz O., Guncu M. M., AKSU M. B., ÖZKAN M., ŞEHİRLİ Ü. S.Objective: It was aimed to identify the contaminant and determine the alternative disinfectant detection in the microbial growth observed in various parts of the cadaver stored in the formalin tank in the dissection laboratory of Marmara University Anatomy Department. We also performed a literature review of this unusual pathogen. Materials and Methods: Swab samples were inoculated on agar mediums. After incubation, matrix-assisted laser desorption ionizationtime of flight mass spectrometry (MALDI-TOF MS) analysis was used to identify the isolate from the detected uniform colonies. Sample solution from the cadaver tank, freshly prepared 5% formalin and 0.55% ortho-phthalaldehyde were used to determine the disinfectant sensitivity of the isolate. Results: According to 16s rDNA sequence analysis, it was concluded as Skermanella aerolata with 99% similarity. In the disinfectant susceptibility test, it was observed that S. aerolata and control bacteria could grow in 5% formalin taken from the cadaver tank. No growth was detected in other disinfectants. Conclusion: To prevent cadaver contamination in anatomy laboratories, the quality control of the embalming solutions and indoor air filtration of the dissection rooms should be checked at regular intervals. Members of Skermanella genus have been identified as environmental organisms in several studies, however, recent researches reported this bacterium as a human pathogen.Publication Open Access 3D Propolis-Sodium Alginate Scaffolds: Influence on Structural Parameters, Release Mechanisms, Cell Cytotoxicity and Antibacterial Activity(MDPI, 2020-11-02) AKSU, MEHMET BURAK; Aranci, Kubra; Uzun, Muhammet; Su, Sena; Cesur, Sumeyye; Ulag, Songul; Amin, Al; Guncu, Mehmet Mucahit; Aksu, Burak; Kolayli, Sevgi; Ustundag, Cem Bulent; Silva, Jorge Carvalho; Ficai, Denisa; Ficai, Anton; Gunduz, OguzhanIn this study, the main aim was to fabricate propolis (Ps)-containing wound dressing patches using 3D printing technology. Different combinations and structures of propolis (Ps)-incorporated sodium alginate (SA) scaffolds were developed. The morphological studies showed that the porosity of developed scaffolds was optimized when 20% (v/v) of Ps was added to the solution. The pore sizes decreased by increasing Ps concentration up to a certain level due to its adhesive properties. The mechanical, swelling-degradation (weight loss) behaviors, and Ps release kinetics were highlighted for the scaffold stability. An antimicrobial assay was employed to test and screen antimicrobial behavior of Ps against Escherichia coli and Staphylococcus aureus strains. The results show that the Ps-added scaffolds have an excellent antibacterial activity because of Ps compounds. An in vitro cytotoxicity test was also applied on the scaffold by using the extract method on the human dermal fibroblasts (HFFF2) cell line. The 3D-printed SA-Ps scaffolds are very useful structures for wound dressing applications.Publication Open Access Distribution and drug resistance of pathogens isolated from patients with hematological malignancies in three-year period(2022-09-01) AKSU, MEHMET BURAK; Arabacı Ç., Aksu M. B.Objective: This study aimed to retrospectively analyze the 3-year findings of bacterial and fungal pathogens isolated from infections in patients with hematological malignancies.Methods: A retrospective analysis of 158 patients with hematological malignancies treated between January 2015 and December 2017 in Okmeydanı Training and Research Hospital, Istanbul, Turkey. A total of 3374 non-consecutive blood samples (n=1954) from 158 patients, urine samples (n=1024), wound swabs (n=94), respiratory samples (n=87), and other samples (CSF, body fluids, etc.) (n=215) were collected. Results: Pathogen growth was detected in 6% (203/3374) of the samples. The most frequently isolated pathogens are coagulase-negative staphylococci (CNS, 20%), E. coli (19%), Klebsiella sp. (17%), and yeasts (16%), followed by Pseudomonas sp., Acinetobacter sp. and Enterococcus sp. (7%, 6%, and 6%, respectively). Candida species were dominant in fungal isolates (26/32; 81.2%). The most commonly detected antibiotic resistance patterns and organisms are carbapenem-resistant Acinetobacter sp. (92%), methicillin-resistant CNS (83%), carbapenem-resistant Klebsiella sp. (65%), MRSA (57%), and vancomycin-resistant Enterococci (VRE, 42%). Conclusion: Bloodstream infections accounted for more than half of all infection episodes. Periodic examination of the clinical and microbiological profiles of infections developing in patients with malignancy is essential for successful treatment management.