Amlacher E, Rudolph C
Acta Histochem Suppl. 1983;27:155-62.
Six suckling growing CBA mice 14 days old (5-6 g of body weight) of the same litter served as test animals in each experiment. 0.1 ml of the dissolved chemicals (15-30 per cent of the LD50 were applied by i.p. injection to 3 animals each (experiment) and an equal number of mice was treated with the solvent only (control). 15 hours later the animals were given a single i.p. injection of 3H thymidine (2 microCi/g body weight) and 50 min afterwards they were sacrificed for autopsy and preparation of autoradiographs. Autoradiographs of nuclei of renal tubular epithelia and of liver epithelium were examined by visual silver grain counting (150 nuclei in each experiment and the same number in the corresponding control). We could demonstrate that carcinogenic compounds of different chemical classes partially inhibit the nuclear incorporation of thymidine in a significant manner over a time period longer than 24 hours. This inhibition may be due as a consequence of a prolonged S phase, expressed as a decrease of the mean of silver grain number per nucleus in comparison with the unaltered control. This decrease is used as a criterion for the suppressive effect of carcinogenic substances on the nuclear DNA synthesis rate. Noncarcinogenic compounds did not show this effect.
在每个实验中，选用同一窝14日龄的6只正在哺乳生长的CBA小鼠（体重5 - 6克）作为实验动物。将溶解的化学物质（15% - 30%的半数致死量）0.1毫升经腹腔注射给每组3只动物（每个实验），同时用等量的溶剂处理相同数量的小鼠作为对照。15小时后，给动物单次腹腔注射3H胸腺嘧啶核苷（2微居里/克体重），50分钟后处死动物进行尸检并制备放射自显影片。通过目视计数银颗粒来检查肾小管上皮细胞核和肝上皮细胞核的放射自显影片（每个实验检查150个细胞核，相应对照中检查相同数量的细胞核）。我们能够证明，不同化学类别的致癌化合物在超过24小时的时间段内会部分地显著抑制胸腺嘧啶核苷的核内掺入。这种抑制可能是由于S期延长导致的，表现为与未改变的对照相比，每个细胞核的银颗粒数平均值降低。这种降低被用作致癌物质对核DNA合成速率抑制作用的标准。非致癌化合物未显示出这种效应。
