Person: ŞAHİN, ALİ
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ŞAHİN
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ALİ
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Publication Metadata only ER stress related lipid accumulation and apoptotic cell death in nonalcoholic fatty liver diesease(ELSEVIER SCIENCE INC, 2017) ŞAHİN, ALİ; Demirel, Tugce; Sozen, Erdi; Sahin, Ali; Karademir, Betul; Ozer, Nesrin KartalPublication Metadata only Design and fabrication of electrospun polycaprolactone/chitosan scaffolds for ligament regeneration(PERGAMON-ELSEVIER SCIENCE LTD, 2021) İNAN, AHMET TALAT; Saatcioglu, Elif; Ulag, Songul; Sahin, Ali; Yilmaz, Betul Karademir; Ekren, Nazmi; Inan, Ahmet Talat; Palaci, Yuksel; Ustundag, Cem Bulent; Gunduz, OguzhanTendon and ligament impairments are among the most familiar injuries of the knee with acute or chronic pain conditions. The defects of anterior cruciate ligament (ACL) stay a known clinical problem. In the present study, the electrospinning method was used to fabricate 10wt.%PCL/(1, 3, 5)wt.%Chitosan (CS) appropriate and biocompatible scaffolds with a similar connective ligament geometry and structure. 10wt.%PCL/3wt.%CS demonstrated higher tensile strength value (0.58854 MPa) than other scaffolds in the tensile test. Moreover, 10wt.%PCL/3wt.%CS scaffolds had high mesenchymal stem cells (MSCs) viability value for all incubation periods. Swelling and degradation behaviours of the ligament-like scaffolds were examined in vitro for 15 days. Results reported that the highest swelling ratio was observed with CS addition for 10wt.%PCL/5wt.%CS scaffolds which value nearly reached to the 270% ratio. Scanning electron microscope proved the geometry of the scaffolds, which were suitable for ligament-like tissue. Attachment of MSCs on the scaffolds proved the network-like structure of the cells on the scaffolds.Publication Open Access Propolis-Based Nanofiber Patches to Repair Corneal Microbial Keratitis(MDPI, 2021-04-28) ŞAHİN, ALİ; Ulag, Songul; Ilhan, Elif; Demirhan, Ramazan; Sahin, Ali; Yilmaz, Betul Karademir; Aksu, Burak; Sengor, Mustafa; Ficai, Denisa; Titu, Aurel Mihail; Ficai, Anton; Gunduz, OguzhanIn this research, polyvinyl-alcohol (PVA)/gelatin (GEL)/propolis (Ps) biocompatible nanofiber patches were fabricated via electrospinning technique. The controlled release of Propolis, surface wettability behaviors, antimicrobial activities against the S. aureus and P. aeruginosa, and biocompatibility properties with the mesenchymal stem cells (MSCs) were investigated in detail. By adding 0.5, 1, and 3 wt.% GEL into the 13 wt.% PVA, the morphological and mechanical results suggested that 13 wt.% PVA/0.5 wt.% GEL patch can be an ideal matrix for 3 and 5 wt.% propolis addition. Morphological results revealed that the diameters of the electrospun nanofiber patches were increased with GEL (from 290 nm to 400 nm) and Ps addition and crosslinking process cause the formation of thicker nanofibers. The tensile strength and elongation at break enhancement were also determined for 13 wt.% PVA/0.5 wt.% GEL/3 wt.% Ps patch. Propolis was released quickly in the first hour and arrived at a plateau. Cell culture and contact angle results confirmed that the 3 wt.% addition of propolis reinforced mesenchymal stem cell proliferation and wettability properties of the patches. The antimicrobial activity demonstrated that propolis loaded patches had antibacterial activity against the S. aureus, but for P. aeruginosa, more studies should be performed.Publication Metadata only Investigation of 3D-Printed Polycaprolactone-/Polyvinylpyrrolidone-Based Constructs(SAGE PUBLICATIONS INC) ŞAHİN, ALİ; Izgordu, Muhammet Sefa; Uzgur, Evren Isa; Ulag, Songul; Sahin, Ali; Yilmaz, Betul Karademir; Kilic, Beyhan; Ekren, Nazmi; Oktar, Faik Nuzhet; Gunduz, OguzhanThe aim of this study is to evaluate the mechanical and biological performance of cartilage-like constructs produced by 3D printing. During the investigation, poly(epsilon-caprolactone) (PCL) and polyvinylpyrrolidone (PVP) were used as a matrix polymer and low-molecular-weight chitosan (CS), hyaluronic acid (HA), and alginic acid sodium salt (SA) were integrated separately with the polymer matrix to fabricate the constructs. Thermal, mechanical, morphology, and chemical properties and swelling, degradation, and biocompatibility behaviors were evaluated in detail. With the addition of 3 fillers, the melting temperature of the matrix increased with the addition of fillers, and PCL/3wt.%PVP/1wt.%HA had the highest melting temperature value. Mechanical characterization results demonstrated that the printed PCL/3wt.%PVP/1wt.%CS displayed the highest compressive strength of around 9.51 MPa. The compressive strength difference between the PCL/3wt.%PVP and PCL/3wt.%PVP/1wt.%CS was 5.38 MPa. Biocompatibility properties of the constructs were tested by mitochondrial dehydrogenase activity, and in vitro studies showed that the PCL/3wt.%PVP/1wt.%HA composite construct had more cell viability than the other constructs by making use of the mesenchymal stem cell line.Publication Metadata only In vitro evaluation of biomaterials for neural tissue engineering(Elsevier Science, Oxford/Amsterdam , 2023-04-01) ŞAHİN, ALİ; YILMAZ, BETÜL; Şahin A., Çıkı B., Yılmaz B.Publication Metadata only Fabrication of tissue-engineered tympanic membrane patches using 3D-Printing technology(ELSEVIER, 2021) ŞAHİN, ALİ; Ilhan, Elif; Ulag, Songul; Sahin, Ali; Yilmaz, Betul Karademir; Ekren, Nazmi; Kilic, Osman; Sengor, Mustafa; Kalaskar, Deepak M.; Oktar, Faik Nuzhet; Gunduz, OguzhanIn recent years, scaffolds produced in 3D printing technology have become more widespread tool due to providing more advantages than traditional methods in tissue engineering applications. In this research, it was aimed to produce patches for the treatment of tympanic membrane perforations which caused significant hearing loss by using 3D printing method. Polylactic acid(PLA) scaffolds with Chitosan(CS) and Sodium Alginate(SA) added in various ratios were prepared for artificial eardrum patches. Different amounts of chitosan and sodium alginate added to PLA increased the biocompatibility of the produced scaffolds. The created patches were designed by mimicking the thickness of the natural tympanic membrane thanks to the precision provided by the 3D printed method. The produced scaffolds were analyzed separately for chemical, morphological, mechanical and biocompatibility properties. Scanning electron microscope (SEM), Fourier-transform infrared (FT-IR) spectroscopy was performed to observe the surface morphology and chemical structure of the scaffolds. Mechanical, thermal and physical properties, swelling and degradation behaviors were examined to fully analyze whole characteristic features of the samples. Cell culture study was also performed to demonstrate the biocompatibility properties of the fabricated scaffolds with human adipose tissue-derived mesenchymal stem cells (hAD-MSCs). 15 wt % PLA was selected as the control group and among all concentrations of CS and SA, groups containing 3 wt% CS and 3 wt% SA showed significantly superior and favorable features in printing quality. The research continued with these two scaffolds (3 wt% CS, and 3 wt% SA), which showed improved print quality when added to PLA. Overall, these results show that PLA/CS and PLA/SA 3D printed artificial patches have the potential to tissue engineering solutions to repair tympanic membrane perforation for people with hearing loss.Publication Metadata only Chemotherapy Resistance: The role of proteasomal degradation and heat shock response(ELSEVIER SCIENCE INC, 2015) ŞAHİN, ALİ; Karademir, Betul; Sozen, Erdi; Bozaykut, Perinur; Altundag, Ergul Mutlu; Yilmaz, Ayse Mine; Sahin, Ali; Corek, Ceyda; Sari, Gulce; Ozer, Nesrin KartalPublication Metadata only Combination of second-generation proteasome inhibitor carfilzomib with bortezomib in four different breast cancer cell lin(2022-01-01) YILMAZ GÖLER, AYŞE MİNE; ŞAHİN, ALİ; YILMAZ, BETÜL; Altundag E. M., Yilmaz A. M., Sahin A., Yilmaz B.Background: Proteasome inhibitors target different pathways in cells and therefore are promising drugs in cancer therapy. The use of these inhibitors is approved mainly in hematological cancers, and recently many clinical trials and preclinical studies have been conducted on efficacy in solid tumors. Carfilzomib is a second-generation inhibitor and was developed to decrease the side effects of bortezomib. Although there are many valid therapies for breast cancer, resistance and recurrence are inevitable in many cases and the proteasomal system plays an important role in related pathways. Objective: This study is a preliminary work to evaluate the combined effects of bortezomib and carfilzomib in four different breast cancer cells. Methods: MDA-MB-231, MCF-7, UACC-2087, and SKBR-3 cell lines were used. Cell viability was determined using bortezomib and carfilzomib alone and in combination. Combination effect values were determined using the Chou-Talalay method. Apoptosis, proteasome activity, cleaved PARP, and HSP70 expressions were analyzed in the determined doses. Results: The response to the combination of the two inhibitors was different in four cell lines. Apoptosis was significantly higher in combination groups compared to carfilzomib in three cell lines except for SKBR-3, and higher in the combination group compared to bortezomib only in UACC-2087. Combination decreased cleaved PARP levels in MDA-MB-231 and MCF-7 and increased SKBR-3 compared to bortezomib. HSP70 levels decreased in combination with UACC-2087 and SKBR-3 compared to carfilzomib. Conclusion: Taken together, the combination of the two inhibitors was more apoptotic compared to carfilzomib and apoptosis was higher only in UACC-2087 compared to bortezomib. This apoptosis data can not be directly correlated to the degree of proteasome inhibition, PARP cleavage, and HSP70 response.Publication Metadata only Proteasome Inhibitors in Cancer Therapy and their Relation to Redox Regulation(BENTHAM SCIENCE PUBL LTD, 2018) ŞAHİN, ALİ; Sari, Gulce; Okat, Zehra; Sahin, Ali; Karademir, BetulRedox homeostasis is important for the maintenance of cell survival. Under physiological conditions, redox system works in a balance and involves activation of many signaling molecules. Regulation of redox balance via signaling molecules is achieved by different pathways and proteasomal system is a key pathway in this process. Importance of proteasomal system on signaling pathways has been investigated for many years. In this direction, many proteasome targeting molecules have been developed. Some of them are already in the clinic for cancer treatment and some are still under investigation to highlight underlying mechanisms. Although there are many studies done, molecular mechanisms of proteasome inhibitors and related signaling pathways need more detailed explanations. This review aims to discuss redox status and proteasomal system related signaling pathways. In addition, cancer therapies targeting proteasomal system and their effects on redox-related pathways have been summarized.Publication Metadata only Effect of electric stimulus on human adipose-derived mesenchymal stem cells cultured in 3D-printed scaffolds(WILEY, 2021) ŞAHİN, ALİ; Bedir, Tuba; Ulag, Songul; Aydogan, Kivanc; Sahin, Ali; Yilmaz, Betul Karademir; Guvenc, Yahya; Bozlar, Michael; Ustundag, Cem Bulent; Gunduz, OguzhanElectrical stimulation has shown great potential for nerve regeneration processes. This makes it attractive to use electrically active materials in the neural scaffold. In this paper, bismuth ferrite (BFO) nanoparticles were synthesized via co-precipitation method and incorporated to 10 wt% polylactic acid (PLA) in chloroform to obtain 3D-printed PLA/BFO biocomposites. The crystallinity of BFO nanoparticles was confirmed by XRD, and we studied its chemical structure with FTIR, as well as the mechanical properties of the 3D-printed composites. in vitro studies show that 3D-printed scaffolds have no cytotoxicity and support the proliferation of human adipose-derived mesenchymal stem cells (hADMSCs). Furthermore, 3D scaffolds embedded with BFO shows the highest cell viability relative to pristine PLA and BFO-lined PLA scaffolds. A 48 hours electrical stimulation on the hADMSC cultured inside the 3D-printed BFO-lined PLA scaffolds indicates that stimulated cells are aligned toward the BFO line. These results could indicate the potential of BFO for directing cells toward damaged tissues.