放射線感受性の異なる正常線維芽細胞、Ataxia Telangiectasia細胞を用いて低線量率照射後の感受性を染色体異常から解析した。細胞はG0期の状態で0.5 Gy/dayの線量率で1-3 Gy照射した。1 Gy当たりの線量で正常細胞では0.36個、AT細胞では3.3個の染色体断片が見られた。3 Gy照射後にG0期染色体とG2期染色体解析を行ったところ、G2期では染色体の誤修復である転座数はG2期で増加がみられたが、8割の誤修復はG0期で見られておりAT細胞ではG0期で多くの誤修復が見られたことからAT細胞では染色体断片の認識に遅れがあり高線量率と同様な感受性を呈することが示唆された。
We exposed normal and ataxia telangiectasia cells to 0.5 Gy per day to gamma ray. Cells were maintained under Go during irradiation. The dose was 1 to 3 Gy and chromosomal aberrations using fusion premature chromosomal condensation technique were analyzed. Giemsa staining showed that 1 Gy induces around 0.36 fragments in normal cells and around 1.35 in AT cells, indicating that AT cells rejoin breaks less effectively than normal cells. We also analyzed chromosomal exchange after exposure to 3 Gy using FISH techniques. AT cells have more misrejoined breaks. When cells irradiated with 3 Gy were subcultured and G2 chromosomal aberrations were analyzed using calyculin-A induced PCC technique, unrejoined breaks decreased and misrejoined breaks increased in both cell lines, suggesting that AT cells begin to rejoin breaks when a certain number of beaks are accumulated and an increased number of exchanges were observed in G0 AT cells, which is similar situation after high-dose-rate irradiation

研究種目 : 若手研究(B)
研究期間 : 2012～2013
課題番号 : 24791338
研究分野 : 医歯薬学
科研費の分科・細目 : 内科系臨床医学・放射線科学