PubMed İndeksli Yayınlar Koleksiyonu / PubMed Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7645
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Article Citation - WoS: 25Citation - Scopus: 30Fabrication of 3d Printed Poly(lactic Acid) Strut and Wet-Electrospun Cellulose Nano Fiber Reinforced Chitosan-Collagen Hydrogel Composite Scaffolds for Meniscus Tissue Engineering(SAGE Publications, 2022) Güneş, Oylum Çolpankan; Kara, Aylin; Baysan, Gizem; Hüsemoğlu, Reşit Buğra; Akokay, Pınar; Ziylan Albayrak, Aylin; Ergür, Bekir Uğur; Havitçioğlu, HasanThe main goal of the study was to produce chitosan-collagen hydrogel composite scaffolds consisting of 3D printed poly(lactic acid) (PLA) strut and nanofibrous cellulose for meniscus cartilage tissue engineering. For this purpose, first PLA strut containing microchannels was incorporated into cellulose nanofibers and then they were embedded into chitosan-collagen matrix to obtain micro- and nano-sized topographical features for better cellular activities as well as mechanical properties. All the hydrogel composite scaffolds produced by using three different concentrations of genipin (0.1, 0.3, and 0.5%) had an interconnected microporous structure with a swelling ratio of about 400% and water content values between 77 and 83% which is similar to native cartilage extracellular matrix. The compressive strength of all the hydrogel composite scaffolds was found to be similar (∼32 kPa) and suitable for cartilage tissue engineering applications. Besides, the hydrogel composite scaffold comprising 0.3% (w/v) genipin had the highest tan δ value (0.044) at a frequency of 1 Hz which is around the walking frequency of a person. According to the in vitro analysis, this hydrogel composite scaffold did not show any cytotoxic effect on the rabbit mesenchymal stem cells and enabled cells to attach, proliferate and also migrate through the inner area of the scaffold. In conclusion, the produced hydrogel composite scaffold holds great promise for meniscus tissue engineering.Article Generating Plan Layouts: a Case Study on Visualization of Implicit Knowledge by “doctor Architects”(SAGE Publications, 2022) Kasalı, AltuğAim: This article presents an opportunistic case with particular focus on instances from an extended procurement operation in which medical professionals run a proactive process involving the generation of layouts through distinct modes of representational practices without any actual collaboration with designers. The questions of inquiry involve an analysis on how the visualizations came into being and a discussion into the content of drawings that was shaped by individuals without any formal design education. Background: Although the literature introduces examples of genuine participation, particularly in healthcare design practices, the instances in which nondesigners demonstrate accomplished skills in spatial reasoning and representation are limited. Method: The research was formulated as a qualitative case study including a series of observations of the activities of the participants followed by interviews recorded at different locations. The investigation also focuses on the features of these authentic graphics which illustrate the intentions of the medical professionals concerning the function of spaces. Results: In this research, the participants went through a labor intensive and elaborate effort to produce “architectural representations” with the intention to convey their implicit professional expertise in the domain. The layouts were introduced to be the vital elements to visualize the implicit knowledge regarding the functioning of space. Conclusions: The productive and creative engagement of clinicians within this research makes the case for a multidisciplinary approach that reframes the limits and potential contributions of participants alongside drawings, which are exclusively claimed by and strategically employed by architects as negotiation devices within participatory design processes.Article Citation - WoS: 14Citation - Scopus: 14Development of Biological Meniscus Scaffold: Decellularization Method and Recellularization With Meniscal Cell Population Derived From Mesenchymal Stem Cells(SAGE Publications, 2021) Kara, Aylin; Koçtürk, Semra; Bilici, Gökçen; Havıtçıoğlu, HasanTissue engineering approaches which include a combination of cells and scaffold materials provide an alternative treatment for meniscus regeneration. Decellularization and recellularization techniques are potential treatment options for transplantation. Maintenance of the ultrastructure composition of the extracellular matrix and repopulation with cells are important factors in constructing a biological scaffold and eliminating immunological reactions. The aim of the study is to develop a method to obtain biological functional meniscus scaffolds for meniscus regeneration. For this purpose, meniscus tissue was decellularized by our modified method, a combination of physical, chemical, and enzymatic methods and then recellularized with a meniscal cell population composed of fibroblasts, chondrocytes and fibrochondrocytes that obtained from mesenchymal stem cells. Decellularized and recellularized meniscus scaffolds were analysed biochemically, biomechanically and histologically. Our results revealed that cellular components of the meniscus were successfully removed by preserving collagen and GAG structures without any significant loss in biomechanical properties. Recellularization results showed that the meniscal cells were localized in the empty lacuna on the decellularized meniscus, and also well distributed and proliferated consistently during the cell culture period (p < 0.05). Furthermore, a high amount of DNA, collagen, and GAG contents (p < 0.05) were obtained with the meniscal cell population in recellularized meniscus tissue. The study demonstrates that our decellularization and recellularization methods were effective to develop a biological functional meniscus scaffold and can mimic the meniscus tissue with structural and biochemical features. We predict that the obtained biological meniscus scaffolds may provide avoidance of adverse immune reactions and an appropriate microenvironment for allogeneic or xenogeneic recipients in the transplantation process. Therefore, as a promising candidate, the obtained biological meniscus scaffolds might be verified with a transplantation experiment.Article Citation - WoS: 25Citation - Scopus: 27Osteogenic Differentiation of Mesenchymal Stem Cells on Random and Aligned Pan/Ppy Nanofibrous Scaffolds(SAGE Publications, 2019) Selamet, Yusuf; İnce Yardımcı, Atike; Baskan, Öznur; Yılmaz, Selahattin; Meşe, Gülistan; Özçivici, EnginThe aim of this study was to develop random and aligned polyacrilonitrile (PAN)/polypyrrole (PPy) nanofibrous scaffolds by electrospinning technique for osteogenic differentiation of mesenchymal stem cells. Nanofibers were fabricated successfully as straight, smooth, and free from bead formation. The average diameter of random and aligned nanofibers was 268(+/- 49) nm and 225(+/- 72) nm, respectively. Alignment process increased the tensile strength of nanofibers 3.9-fold, while the tensile strain of nanofibers decreased by 78%. PAN/PPy nanofibers were hydrophilic with the contact angle value of about 32 degrees and alignment did not affect the contact angle value. Random and aligned PAN/PPy nanofibers were investigated as a scaffold material for osteogenic differentiation of D1 ORL UVA mouse bone marrow mesenchymal stem cells. Cells were able to attach and grow on nanofibers confirmed by cell viability results. Stem cells that were cultured with osteogenic induction were able to mineralize on electrospun nanofibers based on alizarin red and Von Kossa dye staining. For aligned PPy nanofibers, mineralization occurred in the fiber alignment direction. Consequently, PAN/PPy nanofibrous mats in both random and aligned forms would be potential candidates for bone tissue engineering.Article Citation - WoS: 12Citation - Scopus: 17Fish Scale/Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Nanofibrous Composite Scaffolds for Bone Regeneration(SAGE Publications, 2020) Kara, Aylin; Güneş, Oylum C.; Albayrak, Aylin Z.; Bilici, Gökçen; Erbil, Güven; Havitcioğlu, HasanThe aim of this study was to produce three-dimensional, nanofibrous fish scale/poly(3-hydroxybutyrate-co-3-hydroxyvalerate) composite scaffolds as bone filling materials. This is the first report wherein fish scales were used within a nanofibrous matrix for bone regeneration. Composite scaffolds with a cotton wool-like structure (fiber diameter: 560 +/- 64 nm; porosity: 82%) were obtained by incorporating chopped fish scales into wet-electrospun poly(3-hydroxybutyrate-co-3-hydroxyvalerate) nanofibers and freeze-drying. The addition of the fish scales improved the mechanical properties, biomineralization tendency, cell viability, alkaline phosphatase activity, and type I collagen production. Consequently, produced composite scaffolds would be regarded to have the therapeutic capacity in bone tissue damages.Article Citation - WoS: 488Citation - Scopus: 539Major Apoptotic Mechanisms and Genes Involved in Apoptosis(SAGE Publications, 2016) Kiraz, Yağmur; Adan, Aysun; Kartal Yandım, Melis; Baran, YusufAs much as the cellular viability is important for the living organisms, the elimination of unnecessary or damaged cells has the opposite necessity for the maintenance of homeostasis in tissues, organs and the whole organism. Apoptosis, a type of cell death mechanism, is controlled by the interactions between several molecules and responsible for the elimination of unwanted cells from the body. Apoptosis can be triggered by intrinsically or extrinsically through death signals from the outside of the cell. Any abnormality in apoptosis process can cause various types of diseases from cancer to auto-immune diseases. Different gene families such as caspases, inhibitor of apoptosis proteins, B cell lymphoma (Bcl)-2 family of genes, tumor necrosis factor (TNF) receptor gene superfamily, or p53 gene are involved and/or collaborate in the process of apoptosis. In this review, we discuss the basic features of apoptosis and have focused on the gene families playing critical roles, activation/inactivation mechanisms, upstream/downstream effectors, and signaling pathways in apoptosis on the basis of cancer studies. In addition, novel apoptotic players such as miRNAs and sphingolipid family members in various kind of cancer are discussed.