| Autor: |
Jirina Vávrová, Martina Mareková-Rezácová, Doris Vokurková, Sylva Szkanderová, Jan Psutka |
| Předmět: |
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| Zdroj: |
Radiation & Environmental Biophysics; Oct2003, Vol. 42 Issue 3, p193, 7p |
| Abstrakt: |
Most cell lines that lack functional p53 protein are arrested in the G 2 phase of the cell cycle due to DNA damage. It was previously found that the human promyelocyte leukemia cells HL-60 (TP53 negative) that had been exposed to ionizing radiation at doses up to 10 Gy were arrested in the G 2 phase for a period of 24 h. The radioresistance of HL-60 cells that were exposed to low dose-rate gamma irradiation of 3.9 mGy/min, which resulted in a pronounced accumulation of the cells in the G 2 phase during the exposure period, increased compared with the radioresistance of cells that were exposed to a high dose-rate gamma irradiation of 0.6 Gy/min. The D 0 value (i.e. the radiation dose leading to 37% cell survival) for low dose-rate radiation was 3.7 Gy and for high dose-rate radiation 2.2 Gy. In this study, prevention of G 2 phase arrest by caffeine (2 mM) and irradiation of cells with low dose-rate irradiation in all phases of the cell cycle proved to cause radiosensitization (D 0=2.2 Gy). The irradiation in the presence of caffeine resulted in a second wave of apoptosis on days 5?7 post-irradiation. Caffeine-induced apoptosis occurring later than day 7 post-irradiation is postulated to be a result of unscheduled DNA replication and cell cycle progress. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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