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of onset got consolidated in the entire lung. This drug at a dose of 2 mg/kg significantly delayed the progression of pneumonitis (P<0.05) and improved the asymptomatic survival compared to radiation control. 10 mg/kg dose was found to be too toxic. We evaluated the effect of this drug with radiation on A549 through clonogenic assay. Results indicated that radiation dose of 2 Gy led to significant decrease in survival fraction of A549 cells. Drug treatment induced concentration dependent toxicity in the lung cancer cells. The IC 50 of the drug was estimated to be 7µM. When used concurrently with RT showed higher cytotoxicity with an IC 50 of 1µM. suggesting that it does not protect but sensitizes tumor cells to radiation.

investigate dose- and time-dependent response of phosphorylated SMC1 in human lymphoblasts cell lines, phosphorylation of SMC1 responding to the different doses of radiation (0 Gy, 2 Gy, 5 Gy and 10 Gy) in human lymphoblasts cells (A) GM10832, (B) GM10834, and (C) GM10860 were analyzed at indicated time (1, 5, and 15 h) after irradiation. Phospho-SMC1 (Ser-957) and phospho- SMC1 (Ser-360) levels were confirmed by western blotting analysis. Based on the results of the normal cell lines and the human lymphoblast cell lines, peripheral blood mononuclear cells (PBMCs) of twenty humans were tested. Twenty healthy, non-pregnant adults who had not previously received chemotherapy or radiation therapy were recruited. Informed consent was obtained under the review of the institutional review board at Asan Medical Center. PBMCs were obtained from the study subjects, irradiated, and the SMC1 phosphorylation levels were assessed by western blotting. Results In this study, we showed that phosphorylation of SMC1 at Ser-957 and Ser-360 was increased by irradiation in a dose-dependent manner and disappeared gradually after 1-3 hr of peak after irradiation. We also discovered a new phosphorylation site at Ser-360 and showed by western blotting that it is more sensitive to radiation than Ser- 957, especially at low doses. We demonstrated a robust ex-vivo response of phospho-SMC1 Ser-360 in human PBMCs to ionizing radiation exposure. Conclusion Detection of phosphorylation at Ser-360 in SMC1 could be used as a marker of radiation exposure. We demonstrated the feasibility of measuring blood cell-based changes in the phosphorylation level for using an ex-vivo radiation exposure method even after exposure to low doses of radiation. PO-1043 Development of zebrafish embryo model for radiobiology research on laser driven hadron beams E.R. Szabó 1 , T. Tőkés 1 , R. Polanek 1 , Z. Szabó 1 , S. Brunner 1 , S. Czifrus 2 , A. Fenyvesi 3 , B. Biró 3 , E. Beyreuther 4 , J. Pawelke 4 , K. Hideghéty 1 1 ELI-ALPS- ELI-HU Non-Profit Ltd., Scientific Application Division- Biomedical Application Group, Szeged, Hungary 2 Budapest University of Technology and Economics, Institute of Nuclear Techniques, Budapest, Hungary 3 Hungarian Academy of Sciences, Institute for Nuclear Research, Debrecen, Hungary 4 Helmholtz-Zentrum Dresden – Rossendorf- Dresden- Germany- OncoRay – National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus- Technische Universität Dresden, Dresden, Germany Purpose or Objective High power lasers provide the basis of new particle acceleration, resulting in short particle pulses of ultrahigh dose rate. At the actual status of the development, low energy, limited size beams are available under technical conditions for radiobiology experiments. Our main aim was to introduce, optimize and validate a vertebrate system for in vivo experiments to study the biological effects of novel hadron beams. Material and Methods Series of zebrafish embryos in different ages (from 1 hour post-fertilization (hpf) to 72 hpf), in different holders like tubes and 96 well plates varying the number (n) of embryos/well were prepared. For irradiation we used fission neutron (0, 1.25, 1.875, 2, 2.5 Gy), cyclotron- based neutron (0, 2, 4, 6.8, 8.12, 10.28 Gy) and proton

Further work on this drug is in progress and the final results will be presented.

Conclusion The oral formulation of this novel selenocystine derivative not only prevents radiation induced pneumonitis but also reversed the grade of pneumonitis in some of the mice. Initial studies revealed that it also has anti-tumor effects on lung cancer cell. Future studies will focus on further evaluating its effect on lung radioprotection, toxicological effects, in-vivo lung tumor response and mechanistic studies . PO-1042 Biodosimetry Using Radiation-induced Phosphorylation of SMC1 Protein S. Park 1 1 Asan Medical Center, Radiation oncology, Seoul, Korea Republic of Purpose or Objective Biodosimetry has the potential to quantify individual exposures for triage for dose-appropriate medical intervention in the event of a large-scale nuclear event. Structural maintenance of chromosomes 1 (SMC1) protein is a member of the highly conserved cohesin complex that is phosphorylated in response to ionizing radiation. This study was aimed developing a biodosimetry method using SMC1 phosphorylation as a measure of exposure to low-dose ionizing radiation. Material and Methods Firstly, to investigate if phosphorylation of SMC1 shows a dose-dependent accumulation in normal cell lines, the WI-38VA-13 (SV40-transformed human fibroblasts) and the HaCaT (immortalized human keratinocytes) cell lines were collected at the indicated time points (1 or 15 h) after irradiation (0, 2, 5, and 10 Gy) and subjected to western blot analysis. From these analysis, we set the dose to 5 Gy for time-dependent response analysis. Phosphorylation of SMC1 (Ser-360 and Ser-957) levels were estimated after 5 Gy of irradiation in normal cell lines. WI38VA13 (human fibroblasts) and HaCaT (human keratinocytes) were also collected at the indicated time points (0, 1, 3, 6, 12, 18, 24, 36, and 48 h) after irradiation and subjected to western blot analysis. To