الفهرس 
Chemical carcinogensOnly 14 pages are availabe for public view
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Abstract
It is generally recognized that dimethylnitrosamine (DMN) , like most other chemical carcinogens, must be activated by hepatic microsomal enzymes, DMN-demethylases, toexert its hepatotoxic and carcinogenic effects in a wide variety of animals species. It is now established that atleast two enzymes, DMN-methylase I and DMN- demethylase I1 operating at low and high substrate concentrations respective ly , which accomplish this action step. Nitrosamines themselves areeither consumed by the organism as environmental contaminants or may be synthesized in the body from nitrates or nitrites and org’anic amines. Since increased nitrosamines and nitrosatable amines were reported in the urines from bilharzial patients and patients with bladder cancer, it was of inter esttoinvestigate the DMN-activating enzymes in the liver s of mice infected with S. mansoni. Because of the changing hepatic pathology in this case, a time study of the activities of these enzymes was deemed necessary. The effect of pretreatment with lindane; an insecticide of common use, was also included.