The effects of sodium cyanate, tert-butyl isocyanate, and benzyl isothiocyanate on carcinogen-induced neoplasia were studied in experiments in which the test compound was fed starting 1 week following completion of carcinogen administrations. Under these conditions, all three test compounds exerted an inhibitory effect on the occurrence of 7,12-dimethylbenz(a)anthracene-induced neoplasia of the...

Radioactive carcinogens have provided most of our present knowledge about the chemistry of interactions between carcinogens and biological systems. The requirement of radioactive carcinogens has restricted carcinogen-DNA binding studies to chemicals that are readily available in isotopically labeled form, i.e., a minute fraction of all potentially mutagenic or carcinogenic chemicals. To extend ...

Thiotepa is a bifunctional alkylating anticancer drug that is a rodent carcinogen and a suspected human carcinogen. In order to determine the sensitivity of mutant induction in the Hprt lymphocyte assay for detecting tumorigenic doses of thiotepa, Fischer 344 rats were treated for 4 weeks with thiotepa using a procedure adapted from a carcinogenesis protocol. At various times after beginning th...

Many experiments have been described in which a batch of animals are painted or injected with a carcinogen, and the dates recorded when warts or malignant growths are detected. The object of such experiments is usually to compare the potency of different carcinogens, or of different doses or methods of application, or else to compare the sensitivity of different batches of animals to a given ca...

Although it is @ve11 recognized that rats fed azo dyes develop tumors at rates that depend upon the diet fed with the dye (@28), the mechanism by which this is accomplished is unknown. One possi bility is that pertinent diets alter the metabolism of the dye and thus alter the concentration of ef fective carcinogen; another, that diet can effect changes in normal cellular constituents that eithe...

Diabetes mellitus and hepatocellular carcinoma both have detrimental impact on health worldwide. Type II diabetes and liver cancer share many causative factors, but biological correlation between the two diseases still remains elusive. The study was aimed to evaluate the effect of induction of diabetes during the development of hepatocarcinogenesis in rats. Rats were divided into four groups na...

Intragastric administration of 3-methylcholanthrene (MCA) has been reported by others to cause cancers of the glandular stomach and large intestines in an inbred strain of Syrian golden hamsters. In search of the molec ular basis of this process, this study examined the diver sity of the macromolecules and carcinogen-protein com plexes in colon and glandular stomach cytosols during the long-ter...

PURPOSE Nonsteroidal anti-inflammatory drugs (NSAID) are promising chemopreventive agents against colon and other cancers. However, the molecular basis mediated by NSAIDs for chemoprevention has not been fully elucidated. Environmental carcinogens induce DNA mutation and cellular transformation; therefore, we examined the effect of NSAIDs on carcinogenesis mediated by the aryl hydrocarbon recep...

There is much evidence suggesting a possible role of reactive oxygen-derived substances in the pathogenesis of both ulcerative colitis and colon cancer. The antioxidant effects of 5-aminosalicylic acid (the active moiety of olsalazine) on induction of colon cancer in an experimental model using 1,2-dimethylhydrazine were studied in male Wistar rats. The levels of reduced glutathione were signif...

The development of oral squamous cell carcinoma (SCC) shows a positive correlation with the carcinogen exposure that occurs during tobacco and alcohol use. The purpose of this study was to investigate whether the naturally occurring chemopreventive agent, curcumin, modulates expression and function of carcinogen- metabolizing enzymes in human keratinocytes isolated from oral SCC tumors. Dose-re...