ABSTRACT
Objective To explore the influences of the final concentration and adding time of Cytochalasin-B (Cyt-B) on radiation-induced nucleoplasmic bridges (NPB) in cytokinesis-block assay.Methods Hunan peripheral blood samples were divided into 5 final concentration groups (group 2,4,6,8,10 μg/ml) according to different final concentrations of Cyt-B.Moreover,blood samples were divided into 4 adding time groups (group 0,28,40,44 h) according to different adding times of Cyt-B.Blood samples were irradiated with 0 (sham irradiation) and 2 Gy 60Co-rays in vitro,at a dose rate of 1 Gy/min.A cytokinesis-block assay was carried out to prepare NPB samples.The percentages of mononucleated,binucleated and multinucleated cells,as well as the frequencies of NPB and micronucleus (MN) in binucleated cells were analyzed using an optical microscope.Results Nuclear division index (NDI) and the percentages of binucleated cells increased with increased concentration of Cyt-B,and decreased with delayed adding time of Cyt-B (except group 0 h) in both final concentration groups and adding time groups.After exposed to 2 Gy,NPB frequencies were no significant difference (except group 0 h).MN frequencies had the trend of decreased with the increased concentration of Cyt-B,but no significant difference with adding time of Cyt-B.Conclusions In cytokinesis-block assay,different final concentration and adding time of Cyt-B may induce to the variation of NPB frequencies,but there was no significant difference.Appropriate increased final concentration or ahead adding time of Cyt-B can increase the percentage of binucleated cells that help to improve the efficiency of analysis.
ABSTRACT
Objective To explore whether a low dose of 60Co γ-rays could induce the adaptive response in the formation of nucleoplasmic bridges (NPB) in human peripheral blood lymphocytes,and if so,the range of the priming dose.Methods Human peripheral blood samples from healthy males were collected and irradiated with 0,20,50,75,100,150 and 200 mGy (dose-rate was 25 mGy/min) of 60Co γ-rays.After 6 h,the samples were irradiated with a challenge dose of 2 Gy (dose-rate was 1 Gy/min).The cytokinesis-block micronucleus (CBMN) assay was carried out to analyze the NPB and micronuclei (MN) formation in binucleated cells.Results Within the dose range of 0-200 mGy,the yields of NPB and MN increased with irradiation dose of γ-rays and the dose response of NPB followed with a linearquadratic equation of y =(1.5 × 10-4) x2-(5.67 × 10-3)x + 0.598 (R2 =0.893 8).Compared with the samples irradiated with 2 Gy alone,the yields of NPB and MN were significantly reduced when the samples were irradiated with a priming dose of 75-100 mGy before 2 Gy irradiation (U =2.66,2.97,3.96,5.89,P ＜0.05).The biggest decrease ratio of NPB yields approached to 43.2％ at the priming dose of 100 mGy.Conclusions Low doses in the range of 75-100 mGy of 60Co γ-rays could induce the adaptive response of NPB formation in human peripheral blood lymphocytes.
ABSTRACT
Objective To establish the analysis criteria of nucleoplasmic bridges (NPB) and a dose-response curve of NPB frequencies in human peripheral blood lymphocytes irradiated by 60Co γ-rays.Methods Human peripheral blood samples were collected from three healthy males,and were irradiated with 0,1,2,3,4,5 and 6 Gy of 60Co γ-rays.A cytokinesis-block micronucleus assay was carried out to analyze NPBs and micronuclei (MN) in binucleated cells.Results NPBs in binucleated cells at each dose level of γ-ray was conformed to the Poisson distribution.The dose-response curve of the γ-ray-induced NPB frequencies in human peripheral lymphocytes followed the linear-quadratic model y =(1.39 × 10-3)x2 + (4.94 × 10-3)x (R2 =0.981,P ＜ 0.05).Conclusions The dose-response curve of NPB frequencies in human peripheral blood lymphocytes induced by 0-6 Gy 60Co γ-rays was established.