Isonucleolinosis in cell cultures of human meningiomas.

In cell cultures of 13 human meningiomas the internal structure of the nucleolus was stained by the toluidine blue-molybdate method and compared with the karyotype of the tumors. Although some of the meningiomas had lost or gained one or more chromosomes and had undergone structural aberrations, all of them showed isonucleolinosis, which is normally found only in cells with normal karotype. It seems possible that the occurrence of iso- or anisonucleolinosis is not a specific sign of euploidy or aneuploidy, but of benignity or malignancy of the examined tissue.     

Examination by electron microscopy of the San Carlos viruses isolated from children with infectious hepatitis

The results of a study by electron microscopy of the cytopathic effects produced by the San Carlos viruses on cultured human embryo hepatocytes are reported. Examination of liver cells infected with San Carlos virus 6 revealed single virions and crystalline arrays with the hexagonal virion contour measuring an average of 65 to 70 mmu. However, associated with this predominant virion a smaller virus particle with a dimension of 30 to 40 mmu was also found. The nature of this second virion type is not yet clear but its diameter is much larger than the size so far described for the adeno-associated viruses. The size of the smaller virion is probably also too large for it to be a serious candidate for the hepatitis virus but the possible role of these agents in the aetiology of infectious hepatitis, at least in some patients, merits further study.