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Biomedical subjects

P Vic

Publications and source records attributed to P Vic.

64 records · Page 4Linked to original sources
PubMed1979

The fine structure of meningiomas: an attempted classification.

We examined 23 meningiomas by electron microscopy. In each case it was possible to distinguish certain cells with epithelial features (desmosomes, microfliaments, interdigitating extensions) and others with fibroblastic features (collagen fibers). Others cells of transitional form were also seen. The proportion of these cellular types is variable, making it possible to classify meningiomas into seven types of progressing gradually from a purely epithelial type to a purely fibroblastic one.-We found no important ultrastructural abnormalities in the cells. These case reports confirm the uniqueness of meningiomas, which are composed of variously shaped cells but have their origin from a single cellular type. This has double potentiality for fibroblastic and epithelial differentiation.

Cell Differentiation↗
PubMed1979

[Mitotic index modifications in a series of gliomas related to degree of malignancy].

We have measured on semi-thin sections, the mitotic index in 5 benign gliomas and 5 malignant gliomas among a whole of about 80,000 cells in each group, divided into fields of 750 cells on an average. We have differentiated between normal mitoses and abnormal mitoses on one hand, between viable and adequate mitoses and non-viable mitoses on the other. If we take into account the total number of mitoses, the mitotic index is not greatly different between the 2 groups of tumors (about 5 per thousand), although slightly superior in the benign gliomas. If we take into account the viable or adequate mitoses only, the mitotic index is greatly superior among the benign gliomas. These results are discussed according to other data related with the kinetics of proliferation of gliomas and according to the possibility of cellular fusions as a process of a minor spreading of malignant gliomas.

Cell Fusion↗
PubMed1979

[Cell coat modifications in a series of gliomas as a function of malignancy].

We have compared the cell coat of benign gliomas and of malignant gliomas, by Ruthenium Red staining in vitro and by Thiéry's cytochemical reaction in situ. The thickness of the cell coat is not significantly increased by malignancy on the free surfaces of glioma cells. But in malignant gliomas only the cell coat disappears on the intercellular contact zones. These modifications are related to cell fusion characteristics of malignant transformation.

Astrocytoma↗
PubMed1978

[Early effect of estradiol on ultrastructure of chromatin in the endometrium and hormone-dependent mammary tumors].

After in vivo and in vitro administration of aestradiol, the chromatin of lamb endometrium and of hormone-dependent 7,12-dimethylbenzanthracene Rat mammary tumors is rapidly transformed from a condensed into a diffuse chromatin. A stimulation of 3H leucine incorporation into protein was also observed. These modifications were specific for estrogen receptor ligands and for estrogen responsive tissues. In vitro tamoxifen induced pycnosis. These changes could be used to improve the prediction of hormone dependency of human breast and uterine cancers.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1978

[Presence of cell fusions in human malignant glioma].

The observation in malignant glioma of multinucleated cells possessing nuclei at different stages of the cell cycle, micrographs never encountered in benign glioma, led us to propose the hypothesis that, at least in this series of tumors, cell fusion was a criterion of malignancy. We tried to confirm this hypothesis by grafting malignant human gliomas into the brains of new-born mice for the purpose of making hybrid cells possessing human and murine characteristics conspicuous, we found these same multinucleated cells in these grafts. We demonstrated the hybrid nature of these cells by means of a fluorochrome, 33,258 Hoechst, which has the property of fixing itself selectively in the chromocentres of mice. We found quenched human cells, very fluorescent mice cells, and hybrid cells with syncaryons presenting a mixture of fluorescent and quenched chromocentres. These malignant cells are therefore capable of fusing with normal cells at a frequency which remains to be determined.

Animals↗
PubMed1977

Nuclear translocation of the estradiol receptor: partial inhibition by ethidium bromide.

Ethidium bromide (EB), an intercalating drug, has been shown to prevent the in vitro interaction of the estrogen receptor (R) with DNA (André et al., 1976). We have now studied the effect of this drug on the nuclear translocation of R in order to determine whether DNA integrity is needed for this translocation. In a cell-free reconstituted system made of purified nuclei and cytosol, the pretreatment of nuclei by EB prevented approximately half of the R nuclear translocation, but was unable to extract more than 17% of the E2-R previously translocated. A series of indirect evidences suggests that EB inhibits the nuclear translocation of R by interacting with nuclear DNA. The degree of the inhibition was related to the amount of drug bound to nuclei and was in agreement with the degree of ultrastructural modifications of chromatin. R was not irreversibly altered by the drug. The EB inhibition was only observed with DNA-containing particles and with estrogen receptor able to bind to DNA. In surviving uteri the drug also inhibited the R nuclear translocation. These resuts indicate two types of nuclear translocation of R, one sensitive and the other resistant to EB, and suggest that DNA is required for the EB-sensitive translocation.

Animals↗