Dose response of multiple parameters for calyculin A-induced premature chromosome condensation in human peripheral blood lymphocytes exposed to high doses of cobalt-60 gamma-rays.

Many studies have investigated exposure biomarkers for high dose radiation. However, no systematic study on which biomarkers can be used in dose estimation through premature chromosome condensation (PCC) analysis has been conducted. The present study aims to screen the high-dose radiation exposure indicator in calyculin A-induced PCC. The dose response of multiple biological endpoints, including G 2 /A-PCC (G 2 /M and M/A-PCC) index, PCC ring (PCC-R), ratio of the longest/shortest length (L/L ratio), and length and width ratio of the longest chromosome (L/B ratio), were investigated in calyculin A-induced G 2 /A-PCC spreads in human peripheral blood lymphocytes exposed to 0–20 Gy (dose–rate of 1 Gy/min) cobalt-60 gamma-rays. The G 2 /A-PCC index was decreased with enhanced absorbed doses of 4–20 Gy gamma-rays. The G 2 /A PCC-R at 0–12 Gy gamma-rays conformed to Poisson distribution. Three types of PCC-R were scored according to their shape and their solidity or hollowness. The frequencies of hollow PCC-R and PCC-R including or excluding solid ring in G 2 /A-PCC spreads were enhanced with increased doses. The length and width of the longest chromosome, as well as the length of the shortest chromosome in each G 2 /M-PCC or M/A-PCC spread, were measured. All L/L or L/B ratios in G 2 /M-PCC or M/A-PCC spread increased with enhanced doses. A blind test with two new irradiated doses was conducted to validate which biomarker could be used in dose estimation. Results showed that hollow PCC-R and PCC-R including solid ring can be utilized for accurate dose estimation, and that hollow PCC-R was optimal for practical application. [ABSTRACT FROM AUTHOR]