Ameloblastic odontoma in rats induced by N-butylnitrosourea

Four cases of ameloblastic odontomas were found in the Long-Evans rats treated with multiple oral administration of a heavy dose of N-butylnitrosourea. The tumor was found as an expansive enlargement over the mandible and was roentgen-opaque. The tumor was histologically characterized by various elements such as odontogenic epithelium, stellated reticulum tissue, enamel, and/or dentine, and was classified as ameloblastic odontoma.

The 25-km Discontinuity: Implications for Lunar History

The lunar velocity profile and laboratory data on terrestrial and lunar rocks are constraints on models of lunar history. They show that shock-induced microcracks are absent from the rocks present in the moon today at depths of 25 to 60 kilometers. All possible causes of this observation are examined, and the most likely explanations are that either the rocks at depths of 25 to 60 kilometers formed after the major impacts ceased or the microcracks have annealed at temperatures of about 600 degrees C over geologically long times.

Further analysis of the reaction of Paramecium to cigarette paper ash solutions

The reaction of Paramecium caudatum to solutions containing the ash of cigarette paper was consistent with the response of Paramecium aurelia previously reported. After this confirmation, both these species of Paramecium were used as test organisms during a search for the causative agents for the "Paramecium reaction". A qualitative spectrochemical analysis of cigarette paper ash showed that its chief constituent is calcium (97%) with 12 other detected elements present at levels too low to elicit any response from paramecia. Hydroxyl ions in concentrations equivalent to 0.001 M Ca(OH)2, 0.0008 M KOH, or 0.002 M NaOH simulated but did not duplicate the effect of standard cigarette paper ash solution (as of one cigarette paper in 20 ml water). While neutralization caused the three hydroxide solutions to lose their toxicity, the toxicity of cigarette paper ash solution was not appreciably affected by neutralization. Equivalent solutions of facial tissue, filter paper, and a paper towel, burned the same way as cigarette paper, were used as controls. Each of them affected paramecia differently and none simulated the Paramecium reaction. Further, a comparison between ashes from a paperless cigarette, a whole cigarette, and one with two extra roll-your-own wrappers demonstrated a dependence of the Paramecium reaction on cigarette paper ash as well as a direct correlation between the reaction intensity and the amount of cigarette paper ash present.