Testing times for the tests

Article Abstract:

Controversy has flared concerning the value of assessing substances' carcinogenicity (cancer-causing potential) by using certain kinds of tests on animals. Bruce Ames, who developed a test for identifying mutagens (substances that cause cells' genes to change) based on their effects on bacteria, has challenged current approaches whereby animals are exposed to very high doses of presumed carcinogens and then observed for the development of the disease. His objections were not to animal testing as such, but rather to the way the tests are usually carried out and interpreted. More weight is placed on positive results with animals than on results from in vitro (''test-tube'', or tissue culture) experiments, although the latter yield results more quickly. Ames further believes that rodent tests lead to the incorrect identification of many chemicals as carcinogens, based on their abilities to cause damage to animal tissues. This results from the very high doses (maximum tolerated dose) used, far higher than humans could ever tolerate. To compensate for the cells that are damaged by such high doses, new cells are made (mitogenesis), paving the way for more mutations and, ultimately, carcinogenicity. Studies that have attempted to show a link between organ damage and cancer have not yet found such a connection; cancers often occur in organs that do not appear to be damaged. In research by other investigators involving 301 chemicals, certain structural features of the compounds' abilities to cause mutations have been associated with carcinogenicity. Most carcinogenic and mutagenic chemicals were found to be structurally alerting (reactive with DNA). Following this line of reasoning, carcinogenicity could be predicted from a substance's chemical structure, rather than from its performance in a test. More specifically, the position of a chlorine atom may be crucial in determining carcinogenicity. The role of genotoxicity (ability to harm genes) is discussed: carcinogens can be classified as genotoxic or nongenotoxic. In the latter case, substances may alter normal genetic control in certain tissues without actually damaging DNA. The detection of such effects is even more difficult than detection of genotoxic effects. (Consumer Summary produced by Reliance Medical Information, Inc.)

Research, Methods, Animal models in research, Animal research models, Carcinogenicity testing, Ames test, Ames, Bruce

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Trying times for human insulin

Article Abstract:

Human insulin may cause diabetics to lose the ability to sense when they are becoming hypoglycemic due to a hazardous decrease in blood glucose levels. Two researchers, A. Teuscher and W.G. Berger, found evidence linking human insulin with hypoglycemia. However, two other researchers, R. Tattersall and C.V. Gill, studied 50 cases of sudden death among diabetics and were unable to attribute the deaths to any one cause. The controversy over human insulin's safety, including a law suit by diabetics in Britain, may serve to increase public knowledge of diabetes.

Cases, Column, Complications and side effects, Diabetics, Drug therapy, Type 1 diabetes, Insulin, Hypoglycemia

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Best tests for candidates

Article Abstract:

Numerous science-related U.S. organizations have started an initiative, the motto of which is to start a science debate in the American election campaigns. The proponents feel that this is the most appropriate way of choosing the right candidate and focusing on the technological development of the country.

United States, Political aspects, Presidents, Political campaigns, Presidential elections, Electioneering, Scientific development

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