抄録
X-ray bystander effect was demonstrated by the observation of X-ray induced p53 expression area extended from the irradiated point of X-ray microbeam. X-ray microbeam was prepared from micro-capillary equipped in the apparatus for X-ray fluorescence analysis at local areas with operation voltage of 15 kV (XGT-2700, HORIBA, Ltd.). Confluent cells of NB1RBG (human normal skin fibroblast) and A549 (human lung carcinoma) were irradiated with X-ray microbeam emitted from a 100 micrometer capillary for 1 min. The expression area of p53 was determined by the fluorescent antibody technique after 6hr incubation from irradiation. Beam diameter and irradiation dose were estimated by the density on X-ray film. Beam size was found to be enlarged to the diameter of 165 micrometer. The dose rate was approximately 0.3 Gy/min. The results showed that the p53 area was about the same as the size of a beam diameter for A549 cells, while for NB1RGB cells the area exceeded the size of an X-ray microbeam. The present observation can be explained by the presence of the gap junctional function. [J Radiat Res 44:444 (2003)]
