Ames successfully adapted for use with cigarette smoke and other complex aerosols -
The Ames test, a widely used method for determining whether a chemical has the potential to cause cancer, was successfully adapted for use with cigarette smoke and other aerosols complex.
the traditional Ames test is not suitable for use with aerosols and gas, which means that in the past, cigarette smoke toxicity was tested using only the extracted particles of the smoke and not all smoke giving an incomplete picture of the toxic profile. The particulate fraction is only a small part of the whole smoke aerosol, which also comprises a vapor phase and a 6,000 chemicals, including volatile or insoluble components and short duration of combustion products.
The Ames test works by observing the amount of a chemical causes bacteria used in the test to mutate. The standard test comprises up to five strains of bacteria that are mutated in different ways and are genetically modified to require an additional amino acid for growth. Bacteria are embedded in agar at the same time that the test chemical and a small amount of amino acid to enable them to grow and mutate. Mutagenicity test compound is proportional to the number of so-called revertant colonies present at the end of the trial period, ie the number of colonies that have mutated (back) to the state of origin and do not require the amino acid survive.
Now, researchers at British American Tobacco and Covance Laboratories have shown that a modified Ames test can be successfully used to evaluate the toxicological impact of regular cigarette smoke.
researchers have modified the test by changing the bacterial strains used and the method by which they are exposed to the test substance.
Two strains of Salmonella typhimurium and one of Escherichia coli were used -. accepted in accordance with current regulatory guidelines -in more than two S. typhimurium derivatives selected for increased sensitivity to nitroarenes and aromatic amines, known mutagens in cigarette smoke
researchers also modified test by spreading the bacteria over the agar to ensure that they were exposed directly to all the smoke aerosols - greater exposure that submerging. An aerosol system commercially available (10 Vitrocell robot VC) was used to dilute the mainstream cigarette smoke in an adjustable constant flow of air which has been introduced into the bacteria. To quantify the exposure to smoke, quartz microbalances, a tool of newly emerging dosimetry, were loaded into separate wells to measure landing solid particles on the surface.
After exposure to concentrations of four ordinary cigarette smoke, researchers found increases related to the concentration of the number of revertant colonies for Salmonella strains, indicating that smoke causes (some) mutations a dose-dependent manner (doi: 10.1016 / j.mrgentox.2014.04.017).
We have shown activity in a number of strains, some with greater sensitivity than others. We believe this will provide an exhibition platform, as well as more detail the conditions for the test to allow others to use the method in their own lab, "says Debbie Dillon BAT, lead author. "The method is now illustrated with the aid of smoke together, but can be modified to test other aerosols and gases.
The next step is to investigate additional Ames strains and integrate the most effective in a test battery acceptable controller to cigarette smoking.
Ames Test, is widely used for screening the initial genotoxicity of pharmaceuticals and chemicals. The test is governed by (/ ICH OECD) international guidelines, and is a basic element of a preclinical data packet expected by the regulatory bodies for many consumer goods.
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