The SIMULTEST: a new approach to screening chemicals with the Salmonella reversion assay.

A new Salmonella mutagenicity test method is under development to test a chemical with more than one strain simultaneously (the "SIMULTEST"), that is, different Salmonella typhimurium tester strains are used in combination on the same plate. Strains are combined in two sets: strains with plasmid pKM101 (TA97, TA98, TA100, and TA102) and strains without the plasmid (TA1535, TA1537, and TA1538). The SIMULTEST combinations successfully detect the mutagenic activity of five mutagens in different chemical classes. This approach may be useful in reducing the workload associated with mutagenicity testing with Salmonella.

Recommended protocols based on a survey of current practice in genotoxicity testing laboratories: study design.

The most commonly used genotoxicity assays for cultured mammalian cells are mammalian cell mutagenesis, chromosome aberrations/SCE, hepatocyte UDS, and cell transformation. Since their inception, protocols for these assays have been modified in various laboratories. It has been observed that minor but potentially significant method modifications frequently remain unpublished (Swierenga et al., 1983) but should be considered in the development of recommended protocols. The present study was undertaken to determine the current 'state of the art' for these tests. Detailed questionnaires on culture conditions and testing protocols for both stock and test cell populations were designed with the assistance of an international advisory committee and sent to all research and contract laboratories that could be readily identified in Canada, U.S.A. and Europe. Responses from 425 completed questionnaires were analyzed to determine the most commonly used approach and modifications for each procedural step. As expected, the results show a large degree of interlaboratory variation. Detailed protocols for conducting each assay have been prepared and include: stepwise instructions, precautionary measures and practical solutions to common problems associated with each assay; recipes for media and solutions; formulas for quantifying genotoxic responses; reference lists of related assays; guidelines for interpretation; and discussions of the applications, advantages and disadvantages of each test.

Recommended protocols based on a survey of current practice in genotoxicity testing laboratories: II. Mutation in Chinese hamster ovary, V79 Chinese hamster lung and L5178Y mouse lymphoma cells.

Laboratory protocols and guidelines have been developed for the performance of point mutation assays using Chinese hamster ovary (CHO) cells, V79 cells, and L5178Y mouse lymphoma cells. Since only minor differences in the treatment of CHO and V79 cells exist, these two assays could be combined in one procedural guideline. A second protocol was developed for the mouse lymphoma assay in order to incorporate concerns and methods specific to that cell type and genetic locus. The protocols were based primarily on current laboratory practices as determined by responses to a detailed questionnaire completed by North-American and European governmental, university and contract laboratories involved with in vitro mutation testing. This report identifies those modifications to previously described methodologies which are being used on a regular basis, provides recommendations, and also serves to clarify confusing or inconsistent practices.

Recommended protocols based on a survey of current practice in genotoxicity testing laboratories: study evaluation.

The approach used in the survey of current methodologies used in mammalian cell genotoxicity testing (unscheduled DNA synthesis, mutation, cell transformation and cytogenetics testing) is discussed. The recommended protocols, described in the preceding papers, were developed using responses to detailed questionnaires. This summary outlines general observations related to the survey methodology and to the protocols themselves. Also discussed are the qualities of an effective survey; the evolution of a survey and of a protocol; and the contributions and limitations of this study.

Recommended protocols based on a survey of current practice in genotoxicity testing laboratories: I. Unscheduled DNA synthesis assay in rat hepatocyte cultures.

A protocol based primarily on current laboratory practices in the performance of the unscheduled DNA synthesis (UDS) assay with primary rat hepatocyte cultures has been developed. These guidelines were developed using tabulated responses to a detailed questionnaire completed by North American and European governmental, university and contract laboratories involved with the UDS test. This report identifies those modifications to previously described methodologies which are used on a regular basis and also serves to clarify confusing or inconsistent practices. Although this protocol pertains specifically to the use of primary rat hepatocyte cultures, it can be modified to incorporate other types of cells in which certain aspects remain the same.

Recommended protocols based on a survey of current practice in genotoxicity testing laboratories: III. Cell transformation in C3H/10T1/2 mouse embryo cell, BALB/c 3T3 mouse fibroblast and Syrian hamster embryo cell cultures.

A standardized protocol and guidelines for the performance of cell transformation testing in mouse embryo (C3H/10T1/2), mouse fibroblast (BALB/c 3T3) and Syrian hamster embryo (SHE) cells have been developed. The protocol is based primarily on current laboratory practices as determined by responses to a detailed questionnaire completed by North American and European governmental, university and contract laboratories involved with cell transformation experimentation. This report identifies those modifications to previously described methodologies which are being used on a regular basis and also serves to clarify confusing or inconsistent practices.

Recommended protocols based on a survey of current practice in genotoxicity testing laboratories, IV. Chromosome aberration and sister-chromatid exchange in Chinese hamster ovary, V79 Chinese hamster lung and human lymphocyte cultures.

A recommended protocol has been developed for chromosomal aberration and sister-chromatid exchange assays in CHO, V79 and human lymphocyte cultures. The protocol was based on the responses to a detailed questionnaire completed by North-American and European governmental, university, and contract laboratories using these tests. This report identifies those modifications to previously described methods that are used on a regular basis and clarifies confusing or inconsistent practices. These protocols can be modified for use in other types of cells.