The use of a patient monitoring service kept the haematological risks associated with using clozapine within acceptable limits, particularly in view of the benefits of this medication in treatment-resistant schizophrenia.

Ethidium bromide intercalation strongly affects the circular dichroism spectrum of DNA in the region of 230-300 mu, in a complex manner. In this report we present a study that quantitizes the relationships of the circular dichroism spectrum in the region of 230-300 mu and the ethidium bromide induced optical activity centered around 308 mp.We present evidence of two hidden cooperative bands that are probably the negative counterparts of the 308 miu band and 330 mu shoulder positive cooperative bands. The hidden band is quantitatively characterized. We confirm that the direct effect of ethidium bromide on the DNA spectrum is simply linearly proportional to the amount of intercalated dye. We also observe that the ethidium bromide enters freely when there is a molecule intercalated for every 3.sites, but that the intercalation is more difficult when the molecule intercalates at every second site.

Acute inhalation experiments were conducted to determine 24-h LC50 values for adult Sprague-Dawley rats of both sexes exposed to vapors of methyl mercaptan and other reduced-S compounds for 4 h periods. Using calculated gas concentrations, the following LC50 value for each gas and combination was determined: metyhl mercaptan, 675 ppm; dimethyl sulfide, 40,250 ppm; dimethyl disulfide, 805 ppm; hydrogen sulfide, 444 ppm; and an equimolar mixture of methyl mercaptan, dimethyl sulfide, and dimethyl disulfide, 550 ppm. The effects of body and tissue weights, gross metabolic performance, O2 consumption, systolic blood pressure, various blood parameters, and intestinal transit time associated with 3-mo exposures of young adult male rats to chemically verified concentrations of 2, 17, and 57 ppm methyl mercaptan vapor are summarized in this report. No mortality was experienced by any group. Histopathological findings were essentially nil except for microscopic suggestions of liver damage. The most readily apparent phenomenon was the decrease in body weight. Average values of terminal body weights for all exposed groups were lower than that for the sham control group. This difference was significant in the 57 ppm group and followed a statistically significant dose-related trend.

Shearing chromatin, by either sonication or vortex homogenization, introduces significant structural artifacts. These may be detected by the anomalously large increase in the number of ethidium bromide binding sites and the large alteration of the circular dichroism spectra of chromatin. Structural alterations are also suggested by the disappearance of differential light scattering after shearing.

Directly measured and derived geometric and densitometric parameters were obtained by means of the automated image analyzer Quantimet 720-D in Feulgen-stained HeLa cells synchronized by selective mitotic detachment. These data indicate substantial alteration of nuclear morphology during the entire cell cycle, even during the G1 and G2 phases, and the late G1-early S and late S-G2 transitions.