Tumorigenic activity of the tobacco-specific nitrosamines 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), 4-(methylnitrosamino)-4-(3-pyridyl)-1-butanol (iso-NNAL) and N'-nitrosonornicotine (NNN) on topical application to Sencar mice.

The tumor-initiating activities of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), 4-(methylnitrosamino)-4-(3-pyridyl)-1-butanol (iso-NNAL) and N'-nitrosonornicotine (NNN) were evaluated on the skin of female SENCAR mice. A total initiator dose of 28 mumol/mouse of each nitrosamine was applied in 10 subdoses administered every second day. Promotion commenced 10 days after the last initiator dose and consisted of twice weekly application of 2.

Effect of snuff and nicotine on DNA methylation by 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone.

In this study we assayed the effects of snuff and nicotine on the DNA methylation by 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), a powerful tobacco-specific N-nitrosamine. Male F344 rats were pretreated for 2 weeks with either a solution of a snuff extract or 0.002% nicotine in the drinking water.

Contact sensitivity to trivalent chromium compounds.

The investigations confirmed the known fact that for skin tests larger amounts of trivalent chromium compounds are necessary than those of potassium dichromate. It was also observed that some patients react to relatively higher Cr VI and lower Cr III concentrations and others vice versa. Chromium nitrate and chloride release and that of potassium dichromate was determined and converted to the chromium content in the concentrations used for skin tests.

Patch tests with potassium dichromate removed after 24 and 48 hours.

The rate of release in vitro of four potassium dichromate concentrations (0.5, 0.1, 0.