Modeling the Ames Salmonella/microsome assay.

Of the many short-term tests for mutagenicity that have been proposed in recent years, the Ames Salmonella/microsome assay is the single most widely used and most thoroughly validated in vitro test system. This assay uses cells cultured in a soft agar containing a trace amount of histidine to allow growth of auxotrophic bacteria, and is designed to detect reverse mutations from auxotrophic cells to histidine-independent prototrophic cells. In this paper, statistical models that have been proposed for the analysis of Ames test data are reviewed, including those of a mechanistic and empirical nature.

A standardized technique for lower limb radiography. Practice, applications, and error analysis.

The normal standing radiograph, which provides a view of the knee only, is prone to errors of parallax and poor control of patient positioning. A standardized radiographic procedure was developed to control these sources of error. Anteroposterior and lateral views of the lower limb (hip and knee) are obtained without moving the patient from a standardized position; this includes control of ankle position and limb rotation.

Stability of mutagenic nitrosated products of indole compounds occurring in vegetables.

Levels of indolylglucosinolates in Brassica vegetables correlated significantly with the amounts of N-nitroso compounds formed in these vegetables after nitrite treatment. Nitrosation of indole-3-carbinol, indole-3-acetonitrile and indole, hydrolysis products of an indolylglucosinolate, resulted in formation of nitrosated products, which were directly mutagenic to Salmonella typhimurium TA100. The nitrosated products were unstable at pH 2 but stable at pH 8.

Several known indole compounds are not important precursors of direct mutagenic N-nitroso compounds in green cabbage.

In this study we investigated the role of indole-3-acetonitrile, indole-3-carbinol, indole and tryptophan in the formation of N-nitroso compounds in green cabbage extracts. Green cabbage extracts were separated by gel permeation chromatography. Fractions were treated with nitrite, tested for mutagenicity and analysed for total N-nitroso content.

The stability of the nitrosated products of indole, indole-3-acetonitrile, indole-3-carbinol and 4-chloroindole.

The nitrosation rates of indole-3-acetonitrile, indole-3-carbinol, indole and 4-chloroindole and the stability of their nitrosated products were investigated. Each of the nitrosated indole compounds was directly mutagenic to Salmonella typhimurium TA100 in the following order of potency: 4-chloroindole much greater than indole-3-carbinol greater than or equal to indole greater than indole-3-acetonitrile. Total N-nitroso determinations, carried out according to a modified method of Walters et al.