| Brachytherapy with radioactive seed may cause inhibition of the growth of epithe- lial tumors, despite low total radiation doses and comparatively low radiosensitivity of epithelial tumor cells. The induction of apoptosis by low dose radiation, such as deliver- ed in Brachytherapy, was investigated in vitro in human Hela carcinoma cells.125I sources are being used for interstitial implants in various tumor sites, such as the prostate. 125I sources are used in part because therir low-energy phon emissions allow a rapid decrease in dose with incresing distance, and hence minimize the dose to normal tissue.1 Investigation of apoptosis in Hela cells induced by low-dose-rate y radiation (6癈o)Objective To investigate the range of dose in low-dose-rate y irradiation ,and to establish a useful method for radioactive biological effect research of continuous exceeding low does-rate y irradiation, we studied apoptosis of Hela carcinoma cells induced by single low-dose-rate y irradiation in vitro .Methods The cultured cells were exposed to defined radiation doses from a 60Co radiation therapy source. The radiation source delivering IGy/min was given a total doses of 1, 2, 5, 10 and 15 Gy. Using fluorescein-labeled Annexin V and PI , followed by flow cytometry and DNA ladder analysis and confocal microscope , apoptotic cells were detected and quantified. Resu I ts (1) Determination of apoptosis by flow cytometryPercentage of apoptotic cells is increasing with dose and time . After irradiation, the cells were cultured for 168 h. the highest percentage of apoptosis was yielded than any other times. When the cells were irradiated with 1~2 Gy, no significant increase in the number of apoptotic cells could be seen. After a total dose of 5 Gy, however, a significantStudy on the Mechanisms of Tumor Cell Apoptosis and Death Induced by Low Dose-rate y Irradiation Abstractincrease in the ratio of apoptotic/nonapoptotic cells was observed, and apoptosis reached a peak levels of 72.57%?% (P <0.001).(2) Laser confocal microscope scanThe typical appearance of cultured Hela cells stained by annexin V-Fluos for detection of apoptosis is exhibited by a typical plasma membrane-localized fluorescence that is an early sign of apoptosis. PI enter into the cell slowly while in later apoptosis, with special laser which red in center and green around., however, necrotic cell only emitted red laser(3) Apoptotic DNA Ladder AssayThe DNA ladder formation assay confirmed the presence of apoptotic cells, with typical formation of apoptotic fragments. DNA laddering was greatest after a single radiation dose of 5 Gy.(4) Clonogenic AssayOver the dose interval from 2 to 10 Gy with a dose rate of 1 Gy/min, the survival of the cells decreased from 58.95%+0.36% to 1.67%+0.35%(P 0.001). Cone I us i ons low-dose, low-dose-rate y radiation delivered by 60Co sources to Hela cells can induce significant levels of apoptosis. Maximum levels of apoptosis as high as 72.57%+3% at a dose of 5Gy postirradiation can be reached .2 Research in mechanisms underlying tumor cell apoptosis and death induced by continuous low does-rate y irradiationObjective To found the mechanisms of tumor cell death and diversified dose-rate effectinduced by continuous exceeding low does-rate y irradiation , and to confirm the existenceof curative effect in brachytherapy for malignant tumor, we studied apoptosis and themultiplication of Hela carcinoma cells in vitro .Methods According to the first experiment, we can conclude that the doses of apoptosisinduced by low-dose-rate y irradiation.(1) Code IMC6711 iodine-125 seeds have been used in the form of small sealedradiation y sources . We introduce a purpose-built iodine-125 irradiation plaque for low0Study on the Mechanisms of Tumor Cell Apoptosis and Death Induced by Low Dose-rate v Irradiation Abstractdose rate low energy irradiation of cell lines in vitro designed by Gray Lab...
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