Assay positive

Dichloroethane did not act as a tumor initiator or as a complete carcinogen in a rat liver foci assay. Positive results were seen for tumor promotion in the presence of an initiator. It has produced both positive and negative results in Salmonella assays. 

Mutation assay Positive controls (HYC and DMBA) and five concentrations of the test article used with and with metabolic activation Cells exposed to each dose, and the supernatant obtained, and incubated for 20 and 44 hours After a 2-day expression period, the cultures cloned with the restrictive agent trifluorothymidine (allows the growth of TK-/- cells only) or vehicle control... 

MILLER B, POTTER-LOCKER E, SEELBACH A, STOPPER H, UTESCH D and MADLE S (1998) Evaluation of the in vitro micronucleus test as an alternative to the in vitro chromosomal aberration assay position of the GUM Working Group on the in vitro micronucleus test. Gesellschaft fur Umwelt-Mutations-Forschung, Mutat Res. 410, 81-116. 

Nitrites have tested negative in DNA repair bacterial assays. Positive results have been reported in mammalian cytogenetics and sister chromatid exchange studies. 

False positive New assay positive, accepted assay negative. 

False negative New assay negative, accepted assay positive. 

Blood bacterial culture - positive Blood bacterial stain - positive Blood creatinine - increased Blood immunoabsorbent assay - positive Blood liver enzymes - increased Blood sodium - decreased Blood serum creatinine, total - increased Blood WBC - left shift... 

Blood ELISA assay - positive Stool cysts - positive [4]... 

High-Throughput Assay (positive and negative control wells), and test compounds to... 

Since different types of DNA damage are subjected to cellular recombination repair, recombinationless bacteria are usually more sensitive than the wild type. Agents showing increased lethal activity on Rec in comparison with Rec" cells may have caused cellular DNA damage. Because of the simplicity of the procedures, positive chemicals are very easily selected and pooled even from a great number of samples. The DNA-damaging substances are then examined for specificity of induced mutations in bacterial systems. It has been shown that a majority of the rec-assay-positive chemicals are true mutagens. 

The first rec-assay survey on food additives was carried out in 1971 for synthetic dyes, and phloxine (Red Dye No. 104) was found to be positive. The mutagenicity of phloxine was then demonstrated in E. coli WP2 try. AF-2 [2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide], a nitrofuran food preservative, was rec-assayed and found to be a potent mutagen. This substance has been widely used in Japan, and the results initiated a continuing debate on the problem of toxicities due to chemical mutagens. Like other nitrofuran derivatives, AF-2 at first gave negative results with the Ames assay. Positive results appeared later using strains with R plasmid pKMlOl. 

WP2 try and WP2 try her, 9 are found to be positive. Later adoption of Salmonella TA98 and TAIOO revealed mutagenicity in an additional 7 samples in the rec-assay-positive pool (Table 6). It is noteworthy that in a systematic survey of all the rec-assay-negative samples with the Ames reversion assay, no positive result has ever been found except for ETU, which is very weakly positive in TA1535. The rec-assay studies on nitrosation of pesticides have also been successful (Table... 

Metals are probably one of the most susceptible forms in the B. subtilis rec-assay system. Among 121 metal compounds rec-assayed with cold incubation, 44 are positive (Table 8B). These were then examined as to their mutagenicity by the Ames assay, and some of them were found to be positive. The frequency of the mutagenic samples among the rec-assay-positive cases is rather limited compared to the other categories such as food additives and pesticides. It seems that further improvements are required in bacterial reversion assays for metal compounds. Most rec-assay-positive metals either are carcinogens or cause chromosome aberrations or gene mutations in cultured cells. 

While crude extracts of wild type E. coli readily incorporate radio labelled C2-units from malonyl-CoA into long chain fatty acids (Figure 3 left), extracts from fatty acid requiring mutants do not do so. This was the basis for the first FAS complementation tests in E. coli [25] iti which equal amounts of crude extracts from two such auxotrophic mutants were mixed and assayed. Positive results indicated that a FAS moiety defective in one mutant strain was functional and present in the other mutant strain, and vice versa. In cerulenin based complementation assays, the antibiotic replaces one of the mutant strains by selectively inactivating one or more of the condensing enzymes. Low concentrations eliminate... 

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