title: [Analysis of cell kinetics after irradiation by flow cytometry (II)--Evaluation of clonogenic potential of G2 block cells after irradiation by cell sorting].
abstract: When the tumor cells are irradiated, the percentage of the cells in the G2 + M phase and the duration of the cell cycle arrested increase with the irradiation dose. This post irradiation growth inhibition and changes in the cell kinetics observed within 48 hours of irradiation are closely correlated. Cells in the G2 + M phase are reported to be sensitive to irradiation, but little is known about their clonogenic potential. These cells must be separated for evaluation of their clonogenic potential. In this study, the clonogenic potential of irradiated G2 phase arrested cells was examined by the flow cytometric cell sorting technique. Fluorescent Hoechst staining, which allows determination of DNA content in living cells, was used. The results of DNA assay using Hoechst 33342 agreed well with those using PI staining. The concentration of Hoechst 33342 required for the DNA assay and cell sorting is 5 micrograms at which vital staining is possible with 80% cell viability. Although the clonogenic potential of non-irradiated cells was not different between those in G1 and G2 + M phases, that of the cells arrested in the G2 + M phase after irradiation was lower than that of the cells in the G1 phase. The reduction in the clonogenic potential was more notable in the cells subjected to high dose irradiation. A greater number of cells were arrested for a longer period than the cells irradiated at a lower dose. The clonogenic potential of the cells correlated well with the duration of G2 block.
authors.forename: K
authors.initials: K
authors.lastname: Akagi
authors.forename: Y
authors.initials: Y
authors.lastname: Tanaka
mesh_terms: D002469:Cell Separation; D002999:Clone Cells / Q000528:radiation effects*; D003037:Cobalt Radioisotopes; D005434:Flow Cytometry; D005720:Gamma Rays; D006367:HeLa Cells / Q000528:radiation effects; D006801:Humans; D007399:Interphase / Q000528:radiation effects*
chemical_list: D003037:Cobalt Radioisotopes