Multilaboratory comparison of in vitro tests for chromosome aberrations in CHO and CHL cells tested under the same protocols.

Different test results have been reported for the same chemicals in two in vitro chromosome aberration test systems, CHL cells tested by a Japanese protocol and CHO cells tested by the US National Toxicology Program [Sofuni et al., Mutat Res 241:173-213,1990]. Here, laboratories in Japan, the US and the UK tested 9 such chemicals in CHL and CHO cells using the same protocols and found all 9 positive in both cell types; differences in earlier conclusions with these chemicals were due mainly to test protocol, not to different sensitivities of the cells.

Induction of chromosomal damage in mammalian cells in vitro and in vivo by sulfapyridine or 5-aminosalicylic acid.

Sulfapyridine (SP) and 5-aminosalicylic acid (5-ASA) are the two primary metabolites of the anti-inflammatory drug salicylazosulfapyridine (SASP). These two metabolites were studied for induction of chromosomal damage in mammalian cells, in vitro and in vivo, in an attempt to understand better the genetic effects produced by SASP in humans and laboratory mice. To this end, SP and 5-ASA were tested for induction of sister-chromatid exchanges (SCE) and chromosomal aberrations (Abs) in Chinese hamster ovary (CHO) cells in vitro.

Induction of chromosome damage by methylene chloride in CHO cells.

The genotoxicity of methylene chloride was determined using sister-chromatid exchange (SCE) and chromosome aberration assays in cultured Chinese hamster ovary (CHO) cells. Methylene chloride caused extensive chromosome aberrations both with and without metabolic activation. However, the results of the SCE assay were negative for methylene chloride.