Ikeda, Y. (University of Tokyo, Tokyo, Japan) and T. Iijima. Heterocaryosis-like phenomenon in Bacillus subtilis. J. Bacteriol. 83:1025-1028. 1962.-When a mixture of methionine-dependent, histidine-dependent, streptomycin-resistant cells and tryptophan-dependent, streptomycin-sensitive cells of Bacillus subtilis K is plated on minimal medium supplemented with asparagine and streptomycin, tiny colonies consisting of both component cells and X-type cells appear at a frequency of about 10(-6). Because the X-type cell segregates persistently both components and X-type, even after spore formation, it is considered to be a heterocaryon or a syncaryon possessing two kinds of genomes in a common cytoplasm.

Journal Article↗

PubMedDate not supplied

Respective roles of hypoxia and halothane metabolism in halothane-induced liver injury in rats.

To evaluate the respective roles of halothane metabolism and hypoxia in rats with halothane hepatotoxicity, experiments were designed with special reference to blood gas. After pretreatment with phenobarbital (80 mg per kg., i.p.) for four consecutive days, rats were exposed to 1.0% halothane under a mildly hypoxic condition (FiO2 = 14%) for 2 hr. Since halothane anesthesia caused significant decrease in PaO2 levels, rats exposed to a highly hypoxic atmosphere (FiO2 = 10%) in which PaO2 levels were comparable to those in the halothane group, served as the control. In the halothane group, marked centrilobular necrosis and elevation of SGPT activity were observed; neither significant histological lesions nor elevation of transaminase activity occurred in the highly hypoxic group. Although phenobarbital treatment did not decrease PaO2 levels during halothane anesthesia, the serum fluoride level, which appears to reflect quantitatively the reductive pathway of halothane metabolism, increased. These results strongly indicate that halothane metabolism rather than hypoxia, per se, plays a major role in development of halothane-induced liver injury in rats.

Alanine Transaminase↗

PubMedDate not supplied

Lack of carcinogenicity of thiamphenicol in F344 rats.

The carcinogenicity of thiamphenicol (TAP), an antibiotic drug, was examined in Fischer 344 rats of both sexes. TAP was given ad lib. in drinking water at levels of 0 (control), 125 or 250 ppm to groups of 50 male and 50 female rats for 2 yr. The treatment did not affect mortality and no toxic lesions were specifically induced. Furthermore, the incidence of tumours in the treated groups did not show any significant dose-related increase as compared with the control group. The results thus indicate that TAP is neither toxic nor carcinogenic, for any organs or tissues of F344 rats when given continuously at levels of 125 or 250 ppm in drinking water for 2 yr.

Administration, Oral↗