| Objects:To investigate the biological effects of single dose irradiation due to prolonged dose delivery times in Anip973 lung adenocarcinoma cell lines.Methods:Anip973 cells were irradiated with 6MV X-ray at single doses in different prolonged dose delivery times in vitro.Light microscope was used to observe cell morphologic in different time points after X ray irradiation.Eeach group cells were collected at different time points after irradiation,.Clone assay analysis was used to detect the survival fraction of cells after irradiation and draw the pillar-form graph; Flow cytometry was used to detect the apoptosis rates and cell cycle redistribution. "Comet" analytic was performed to detect the incipient DNA damage quantita-tively after irradiation;perspective electron microscope was to observe cell morpho-logic and the modus of death in 24h after irradiation.Statistical analysis data were processed by SPSS 13.0 software.Results:1,Compared to the control group,Anip973 cells in other groups showed changes in morphology after irradiation,cell's volume was enlarged;2,Cells apoptosis changes:Cells apoptosis was higher in prolonged dose delivery times 76min of 10Gy than the other groups(hasten radiation,17min,35min); the cells apoptosis rate appeared decrease tendency to follow increasing prolonged dose delivery times after radiation 72h;cells apoptosis didn't appeared evident ascensus or decrease when the observation time was 24h,48h and 72h in hasten radiation,prolonged dose delivery times 17min and 35min for 20Gy,but the apoptosis appeared ascensus tendency to follow extension of the observation time for prolonged dose delivery times 76min;3,Cells cycle changes:X-ray irradiation can cause G2/M phase blockage in cell cycles of this cell line.The hasten radiation and prolonged dose delivery times 17min of 10Gy keeped on G2/M phase blockage,the hump was to continue increasing in 72h for 35min group;the hump appeared in 48h for prolonged dose delivery times 76min and decreased in 72h;The hump was to achieve point(almost 100%) in 72h for hasten radiation of 20Gy,but the hump appeared in 48h for prolonged dose delivery times 17min,35mhi,76min and decreased in 72h; 4,The survival fraction:the survival fraction was increased following the extension of prolonged dose delivery times,the pillar-form graph appeared ladder,the survival fraction was higher in 76min group than other groups and had significance compared other groups(P=0.000,0.012,0.013).there is no clone to form in 20Gy;5,Comet analytic was to detected DNA's damage quantitatively,the degree of DNA's damage was abatement following the extension of prolonged dose delivery times,it was severer in the same complete times for 20Gy than 10Gy;6,Perspective electron microscope observed the way of cell's death:the volume was enlarged after irradiation,nucleole accreted,nucleolar margination,some cell surface specialized structures were to disappear and without microvilli,a small quantity broaden rough endoplasmic reticulums were in intracytoplasm and communicated with surrounding through cell membrane.There were apoptosis cell's characteristic and without oncotic necrosis.But it was can see oncotic necrosis when we continued give two coups of 20Gy.Conclusions:1,Cell's volume of Anip973 after X ray irradiation was enlarged;2,Low dose rate irradiation induced cell apoptosis,sublethal damage repair was a important mechanism in low dose rate irradiation;3,X ray irradiation can cause G2/M phase arrest which conforms to the traditional radiobiology concept,the time was longer of G2/M phase arrest for increasing of relative dose rate;4,The radiobiological effects was decrease during the low dose rate irradiation in single dose irradiation;5,Perspective electron microscope observed the way of cell's death: There were apoptosis cell's characteristic and without oncotic necrosis in 24h.But it was can see oncotic necrosis when we continued give two coups of 20Gy. |
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