Occurrence and ultrastructure of a variant (rho) form of Mycoplasma

The ultrastructure of a variant (rho) form of Mycoplasma is described. The rho-forms are characterized by dark-ground light microscopy as relatively rigid, unbranched, filamentous organisms with discoidal swellings, and by electron microscopy by the presence of an intracytoplasmic axial fiber extending throughout the length of the cell and associated with a terminal structure of characteristic appearance. In negatively stained preparations the fiber presents a pattern of transverse light and dark major bands, the dark band being divided by a central minor light band. The periodicity of the banding varies from 12.0 to 14.5 nm, and the width of the fiber varies from 40 to 120 nm. The fiber appears to be composed of fibrils aligned parallel to the long axis. The evidence indicates that the fiber contains protein and is devoid of nucleic acid. rho-Forms were commonly found in Mycoplasma strains derived from goats and occasionally in bovine strains. They may have a wider distribution, as the growth medium was shown to be important both for the expression of the rho-character and for the selection of the rho-variant. The functional significance, if any, of the fiber and the terminal structure is unknown.

Carboxyhemoglobin elevation after exposure to dichloromethane

Inhalation of dichloromethane vapor in concentrations of 500 to 1000 parts per million for 1 to 2 hours promptly initiated the formation of significant quantities of carbon monoxide in human subjects. The evidence suggests that carbon monoxide may be a metabolite of dichloromethane and, that exposure to concentrations of dichloromethane below the industrial threshold limit values may result in the formation of carbon monoxide in amounts that exceed the allowable limits.

Protection by ethanol against the toxic effects of monofluorethanol and monochloroethanol

Ethanol protects rats and monkeys against fatal doses of monofluoroethanol and monochloroethanol. In rats treated with ethanol the LD50 for fluoroethanol was found to be more than 20 times that in unprotected animals, for chloroethanol it was about 4 times greater. In monkeys too, the lethal effects of these compounds are diminished by treatment with ethanol.