Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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Author: search.filters.author.Tosun, ÇiğdemPublisher: search.filters.publisher.Izmir Institute of Technology

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  • Master Thesis
    The Effect of Glibenclamide in Lipopolysaccharide Stimulated Brain Microvascular Endothelial Cells
    (Izmir Institute of Technology, 2019) Cihankaya, Hilal; Tosun, Çiğdem; Tosun, Çiğdem; 04.03. Department of Molecular Biology and Genetics; 04. Faculty of Science; 01. Izmir Institute of Technology
    Endothelial cells are essential components of the blood brain barrier (BBB) that regulate the exchange of solutes between the vasculature and the brain parenchyma. The integrity of the BBB is disrupted after central nervous system (CNS) injuries, and it has been associated with the Sur1-Trpm4 channels. Once these channels are opened, Na+ flows into the cells causing edema and cell death. To mimic CNS injuries in vitro, lipopolysaccharide (LPS) was used as an endotoxin to initiate proinflammatory mediators to increase endothelial permeability, and glibenclamide was used as an antagonist of Sur1-Trpm4 channels to reduce the inflammatory response and to maintain the structural integrity of BBB proteins. To demonstrate the role of glibenclamide following LPS stimulation, we determined the cytotoxicity of LPS in bEnd.3 cells by cleaved caspase-3 expression and propidium iodide staining. We also investigated the protective effect of glibenclamide on NF-B translocation, and BBB proteins; collagen IV (COL IV) and zonula occludens 1 (ZO-1) in LPS stimulated bEnd.3 cells. Our results revealed that 1g/ml LPS exposure was sufficient for NF-B nuclear translocation, along with a statistically significant decrease in the expressions of COL IV and ZO-1 proteins, and a significant increase in cell death. We also demonstrated that glibenclamide was able to restore the expressions of COL IV and ZO-1, significantly reduce NF-B translocation, and cell death. Taken together, LPS induction in bEnd.3 cells can be used to investigate endothelial cell dysfunction due to inflammation in stroke and trauma models and glibenclamide can be used as a protective drug to inhibit LPS stimulated inflammatory response, cell death and disruptions in the structures of key BBB proteins.
  • Master Thesis
    Effects of Polyether Antibiotics on Autophagy
    (Izmir Institute of Technology, 2017) Tosun, Çiğdem; Tosun, Çiğdem; Bedir, Erdal; Tosun, Çiğdem; Bedir, Erdal; 04.03. Department of Molecular Biology and Genetics; 03.01. Department of Bioengineering; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of Technology
    Treatment of cancer is one of the crucial enigma for scientific world and that’s why much effort needs to be put in place for the resolution of this challenge in alternative ways. Autophagy is believed to have an important role in tumor development and progression. The natural polyether antibiotics might be important chemotherapeutic agents to cure cancer by modulating autophagy. The primary goal of this study was to investigate the cytotoxic effects and autophagic mechanism of actions of three polyether antibiotics, one of which was a new secondary metabolite isolated from the marine Streptomyces cacaoi. The effects of these polyether antibiotics were investigated along with previously known autophagy modulators from the same group (Monensin). To achieve this goal, cytotoxicities of these polyether type compounds on three different type of cancer cell lines along with two healthy cell lines were investigated followed by a search to reveal the effects of these compounds on autophagy in cancer cell lines. Methodology of this study consists of mammalian cell culturing, cytotoxicity screening, staining and quantification of acidic compartments inside the cells and studying different autophagy markers along with other associated proteins under various conditions by using Western blotting. This study revealed that the tested polyether antibiotics were autophagy inhibitors as well as inducers of apoptosis in cervical, colorectal and prostate cancer cells. The obtained results will be of significance for the field of anticancer drugdevelopment; however, before one places these secondary metabolites as potential drug candidates, further studies including in vivo experiments are warranted.