The yield of DNA double-strand breaks (DSBs) is sure to be influenced by theenvironment around DNA molecule. Inverse pulsed-field gel electrophoresis (PIGE) has beenapplied to compare the sensitivity of B16 cells and ...The yield of DNA double-strand breaks (DSBs) is sure to be influenced by theenvironment around DNA molecule. Inverse pulsed-field gel electrophoresis (PIGE) has beenapplied to compare the sensitivity of B16 cells and their DNA in DSBs induced by 75 MeV/u16O8+ beam. Results show that the percentages of DNA released from the plug(PR) in bothkinds of tile samples increase with the dose and approach a similar quasi-threshold of about81%. A simple new equation was presented to calculate the break level of DNA molecules.Within a certain dose, the relationship between the break level and the dose is linear. Theyield of DSBs in deproteinized DNA was 1.11 DSBs/100 Mbp/Gy, while that in intact cells was0.60DSBs/100Mbp/Gy. It is testified that deproteinized DNA is more sensitive to oxygen ionsirradiation than intact cells.展开更多
The developed track detector consists of two parts: a small drift region to obtain a good tracking and a relatively large multiplication region for getting an enough high gain at low pressure. All the track detector c...The developed track detector consists of two parts: a small drift region to obtain a good tracking and a relatively large multiplication region for getting an enough high gain at low pressure. All the track detector can be moved in the direction perpendicular to the beam by means of a micrometric screw. An automatic system allows the counting gas to flow continuously at constant pressure through the detector during the measurements. The system can measure ionization distributions at a few nanometer range.展开更多
Inhibition effects, control probabilities and pathology tissue changes of mouse transplanted tumors S180 after irradiation with 50 MeVu 12C6+ ions are reported. Doses of single irradiation were 0.5, 1, 2, 5, 10, 20, 4...Inhibition effects, control probabilities and pathology tissue changes of mouse transplanted tumors S180 after irradiation with 50 MeVu 12C6+ ions are reported. Doses of single irradiation were 0.5, 1, 2, 5, 10, 20, 40 Gy, respectivelyl at a dose rate of 3 Gy/min. Observing time was 24 days. The results show that each group had significant inhibition action on S180 tumors and all inhibitory probabilities were more than 90%; the initial time of inducing tumor inhibition effects were within one week in high dose groups （20, 40 Gy）, and after two weeks in medium dose groups （5, 10 Gy） and low dose groups （0.5, 1, 2 Gy）; also, inhibitory effects in high dose groups were obviously greater than other groups （p <0.05）; tumor control probabilities were different in each group) those in high dose groups （20, 40 Gy） were higher and TCD50 （50% tumor control dose） was 20Gy; the results for curing tumors are different in different doses; pathology inspection presented here were tumor tissue necrosis and degeneration in each dose group and they depended on doses.展开更多
文摘The yield of DNA double-strand breaks (DSBs) is sure to be influenced by theenvironment around DNA molecule. Inverse pulsed-field gel electrophoresis (PIGE) has beenapplied to compare the sensitivity of B16 cells and their DNA in DSBs induced by 75 MeV/u16O8+ beam. Results show that the percentages of DNA released from the plug(PR) in bothkinds of tile samples increase with the dose and approach a similar quasi-threshold of about81%. A simple new equation was presented to calculate the break level of DNA molecules.Within a certain dose, the relationship between the break level and the dose is linear. Theyield of DSBs in deproteinized DNA was 1.11 DSBs/100 Mbp/Gy, while that in intact cells was0.60DSBs/100Mbp/Gy. It is testified that deproteinized DNA is more sensitive to oxygen ionsirradiation than intact cells.
文摘The developed track detector consists of two parts: a small drift region to obtain a good tracking and a relatively large multiplication region for getting an enough high gain at low pressure. All the track detector can be moved in the direction perpendicular to the beam by means of a micrometric screw. An automatic system allows the counting gas to flow continuously at constant pressure through the detector during the measurements. The system can measure ionization distributions at a few nanometer range.
基金President Special Foundation of the Chinese Academy of Sciences
文摘Inhibition effects, control probabilities and pathology tissue changes of mouse transplanted tumors S180 after irradiation with 50 MeVu 12C6+ ions are reported. Doses of single irradiation were 0.5, 1, 2, 5, 10, 20, 40 Gy, respectivelyl at a dose rate of 3 Gy/min. Observing time was 24 days. The results show that each group had significant inhibition action on S180 tumors and all inhibitory probabilities were more than 90%; the initial time of inducing tumor inhibition effects were within one week in high dose groups （20, 40 Gy）, and after two weeks in medium dose groups （5, 10 Gy） and low dose groups （0.5, 1, 2 Gy）; also, inhibitory effects in high dose groups were obviously greater than other groups （p <0.05）; tumor control probabilities were different in each group) those in high dose groups （20, 40 Gy） were higher and TCD50 （50% tumor control dose） was 20Gy; the results for curing tumors are different in different doses; pathology inspection presented here were tumor tissue necrosis and degeneration in each dose group and they depended on doses.
