Browsing by Author "Yurt, Aysegul"

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Ionizing Radiation-Induced Testicular Oxidative Stress and Apoptosis: The Role of Small GTPase RhoA
(Taylor & Francis Ltd, 2025) Manisaligil, Yasar Aysun; Yurt, Aysegul; Ozkan, Cemre Ural; Micili, Serap Cilaker; Sisman, Gizem; Cavdar, Zahide; Gumustekin, Mukaddes
PurposeThe effects of ionizing radiation on living organisms are mainly known as the generation of reactive oxygen species (ROS), apoptosis, and DNA damage. Small GTPases (RhoA, Rac1, Cdc42) are known to have roles in the regulation of oxidative stress and apoptosis. The aim of this study was to investigate the role of the RhoA molecule in testicular tissue damage due to oxidative stress and apoptosis induced by ionizing radiation.Material and methodIn this study, testicular tissues and blood samples obtained from our previous study were examined. In that study, rats were exposed to ionizing radiation at three different doses (0.02 Gy, 0.1 Gy, 5 Gy). Then tissue and blood samples were taken at three different times (2 hours, 24 hours, and 7 days) after irradiation. Immunohistochemical staining was performed to evaluate RhoA and cleaved caspase-3 expressions, while RhoA activity was assessed by G-LISA assay in testicular tissues. Serum malondialdehyde (MDA) levels and superoxide dismutase (SOD) activity were analyzed to evaluate oxidative stress.ResultsThe expression and activation of RhoA demonstrated a time-dependent increase across all levels of radiation doses. Similarly, the expression of cleaved caspase-3 also exhibited a time-dependent increase, consistent with the effects of radiation-induced damage observed in all experimental groups. After exposure to radiation, serum levels of MDA increased, while the activity of SOD decreased.ConclusionOur findings suggest that RhoA may contribute to radiation-induced testicular tissue damage by increasing oxidative stress and apoptosis.
Citation - WoS: 1
Simulation of Water Equivalency of Polymer Gel Dosimeters With Gamos
(Aves Press Ltd, 2020) Ozbay, Turkan; Yurt, Aysegul; Ozsoykal, Ismail
Purpose: Polymer gel materials are used as dosimeters to provide three dimensional radiation dose distribution. An ideal gel dosimeter should offer radiological properties equivalent to water. This study aims to determine and compare the water equivalencies of various new polymer gel mixtures using Geant4-based Architecture for Medicine-Oriented Simulations (GAMOS) software program. Methods: To do this, percentage depth dose curves of the simulated polymer gel mixtures were compared with water curves. Different combinations of materials from 2 main classes were used in the mixtures: (1) Sodium Carboxymethyl Cellulose (SODIUM CMC), Polyvinyl Alcohol (PVA) and Polyethylene Glycol (PEG) as gel matrix, (2) 2-Hydroxyethyl Methacrylate (HEMA), 1-Vinyl-2-Pyrrolidinone (VP) and Diethylene Glycol Dimethacrylate (DEGDMA) as monomer. Each mixture also contained ultra-pure water and an antioxidant material called Tetrakis Hydroxymethyl Phosphonium Chloride ( THPC). Results: Percentage depth doses of gel mixtures and water was calculated for 6, 18 MV and 50, 70, 100, 150 kVp X rays. The mixture sample showing radiological behavior nearest to water over all energies was observed to be 31a (Water, PEG, HEMA, THPC), while the largest difference is observed in 11a (Water, SODIUM CMC, HEMA, THPC). Conclusion: As a result, simulated gel formulations were found to be radiologically water equivalent.