^(60)Coγ-线不同方式照射诱发猕猴染色体畸变的比较研究

COMPARATIVE STUDIES ON CHROMOSOME ABERRATIONS IN RHESUS MONKEYS INDUCED BY ^(60)Co γ RAY IRRADIATION UNDER DIFFERENT IRRADIATION CONDITIONS

本研究以γ线不同方式照射猕猴,对所诱发的染色体畸变进行了比较研究。一次急性照射的剂量率为223 mGy/min;分次累积照射的剂量率为223 mGy/min,每次照射0.25 Gy,每周照射一次;慢性连续照射以0.26 mGy/min的剂量率,每天照射190分钟,每周连续照射5天,总累积剂量均为2.0 Gy。实验结果发现,一次急性照射的主要畸变类型为双着丝点体和无着丝点断片,分次累积照射和慢性连续照射则以无着丝点断片为主。各照射组动物的染色体畸变率都随着照射剂量的增加而呈线性增高,其中一次急性照射组的染色体损伤比其他两组的要严重得多,但后两组之间却无明显差异,且当累积剂量达到1.0Gy以上时,后两组的无着丝点断片率随着累积剂量的增大而升高缓慢。停照后一年内染色体畸变率基本上降到对照水平。

Rhesus monkeys were irradiated by ^(60)Coγ ray exposure under diff-erent conditions, and comparative studies on their chromosome aberrations have beenmade. The dose rate of single acute irradiation was 223 mGy/min, the dose rate offractionated cumulative irradiation was 233 mGy/min, and the dose of 0.25 Gy wasdelivered once a week, the dose rate of chronic continuous irradiation was 0.26mGy/min for 190 min, 5 days per week. The total cumulative dose for each groupwas 2.0 Gy. It was found that the types of chromosome aberrations were mainly dicentric abe-rrations and acentric fragments in single acute irradiation. and acentric fragments inboth fractionated cumulative and chronic continuous irradietion groups. The frequen-cles of chromosome aberrationns in these groups increase linearly with increasing cose.The degree of chromosome damage in single acute irradiation group was much greaterthan those in the other groups, but degree and characteristics of chromosome damagebetween fractionated cumulative and chronic comtinuous irradiation groups was notsignificantly different. Acentric fragments in lymphocyte chromosomes ceased to increa-se when the cumulated dose in fractionated cumulative or chronic continuous irradia-tion reached to more than 1.0 Gy. The frequencies of chromosome aberrations basica-lly decreased to control level within a year following the termination of irradiation.