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Biomedical subjects

C Foa

Publications and source records attributed to C Foa.

At least 55 records · Page 3Linked to original sources
PubMed1981

Cell surface fixation of alloantigen bearing plasma vesicles in the presence of polyethylene glycol.

The fixation of plasma vesicles at the surface of intact mouse spleen or tumor cells was studied in order to introduce the foreign alloantigens of the vesicles into the plasma membrane of these cells. A 3-6-fold increase of fixation of radioiodinated vesicles was obtained when cells and vesicles were incubated in the presence of polyethylene glycol 1500 (PEG 1500). The fixation of vesicles on the surface of cells was demonstrated by scanning electron microscopy. Cells treated with vesicles in the presence of PEG acquired the corresponding membrane alloantigens, as demonstrated by cellular binding radioimmunoassay. However, sensitivity to antibody-dependent lysis was obtained only when vesicle fixation was achieved in the presence of both wheat germ agglutinin and polyethylene glycol. The introduction of foreign alloantigens in the plasma membrane of the treated cells might help to define the functional properties of these molecules.

Animals↗
PubMed1979

[Correlation between differentiation and malignancy in human malignant melanocytes "in vivo" and "in vitro" (author's transl)].

The relationships between differentiation and malignant transformation were studied in human malignant melanomas in vivo and in vitro. Melanocyte differentiation was assessed by ultrastructural morphological characteristis (the appearance of the melanosomes and related structures) localization of dopa-oxidase and assay of 5-S-cysteinyldopa, a specific metabolite. The transformed characteristic of the cells in vitro was evaluated by their ability to give rise to established cell lines, karyological modifications and heterotransplantation in Nude mice and Syrian hamsters. Morphological variability of the cells in malignant melanomas is accompanied by variability in the localization of dopa-oxidase, the level of 5-S-cysteinyldopa, chromosome pattern and their heterotransplantibility. The lack of pigmentation in some malignant melanoma lines can result from either an irreversible loss of some functions which give rise in melanization and the malignancy in maintained, or by phenomenon of regulation determined by intra or extra-cellular factors with the loss of heterotransplantability. Modulation phenomena affecting tumorigenicity and pigmentation although sometimes concomitant are not identical.

Animals↗
PubMed1979

[Cellular differentiation and malignant transformation (author's transl)].

The mechanisms and determination of differentiation of normal and cancer cells were compared by distinguishing them from the phenomena of regulation, retrodifferentiation and maturation. Reference is made to the laws of order in time and space which are superimposed on the common genetic code during the various types of differentiation. In conclusion, the particular mechanisms of malignant differentiation are discussed by taking melanoma and tumor formation by papova-viruses as examples.

Animals↗
PubMed1978

Correlation between characteristics of transformation and malignancy of intra and interspecific somatic hybrid cells.

The transformed properties of five hybrid cell lines which had either one or another parent in common were studied and compared with their tumorigenicity. Three hybrid cell lines, derived from the Chinese hamster DC-3F/ADX/Aza line, were resistant to actinomycin-D. This property seemed to be correlated with the presence of a marker chromosome from the common parent. The tumorigenicity was intermediate between those of the parent cell lines. On the other hand, agglutinability by concanavalin A (Con A) was variable. Three hybrid cell lines which had either the A9 or the clone 1D (both derived from mouse fibroblasts) showed very similar transformed characteristics, but two were tumorigenic and one not so. It appears from this study that the properties of the hybrid cell lines can be influenced more by one parent, depending on the genes retained at chromosome segregation. The limits of Con A agglutination as a characteristic of transformation and the validity of the check pouch grafts as tumorigenicity test for malignant human cell lines are discussed.

Agglutination↗
PubMed1977

Ultrastructure of spontaneously differentiated human malignant melanocytes cultured from primary tumors.

Ultrastructural study of early subcultures and established lines of human malignant melanocytes derived from primary tumors showed that melanocytes passed through a phase of dedifferentiation during which they took on a fibroblast-like appearance; then they had a phase of spontaneous redifferentiation. The fibroblast-like cells were characterized by the presence of network-like organelles in their cytoplasm, and the melanocytes by melanosomes.

Cell Differentiation↗
PubMed1977

Cellular localization of tyrosinase in human malignant melanoma cell lines.

Human malignant melanocytes show characteristic morphologic modifications which are particularly evident in their specific organelles: melanosomes. These modifications are conserved in cell culture. The ultrastructural localization of tyrosinase, the enzyme which converts tyrosine and dopa into melanin, was determined in 13 human melanoma cell lines. The different cell lines possess 4 distribution patterns of melanin synthesis based on dopa oxidase activity. The two first pathways, which involve the Golgi apparatus, seem to differ by the amount of enzyme within this organelle. The third pathway mainly involves the smooth endoplasmic reticulum, whereas tyrosinase is visible only in vesicles in the fourth. Some cells synthesize the enzyme in the manner observed in very early embryos.

Catechol Oxidase↗
PubMed1977

Ultrastructural comparison between cultured and tumor cells of human malignant melanoma.

Tumor cells from 28 human malignant melanomas were compared by electron microscopy with cultured cells of 17 established human melanoma cell lines derived from the same types of tumors. Both tumor and cultured cells were classified into five types according to their different fine-structural characteristics. There was a correlation between the cell types observed in the tumor fragments and in the cell lines. This evidence suggests that cultured human melanoma cells retained in vitro the characteristics of the melanoma cells in vivo, from which they were derived.

Cells, Cultured↗
PubMed1976

Morphologic study of virus-like particles in a case of acute leukemia.

Virus-like particles, grouped in clusters not bound by a membraine, were seen in electron micrographs of fresh leucoblasts of an acute leukemic patient. They consisted of large (100-nm diameter), round particles apparently composed of subunits. Tubular structures (30-50-nm diameter) were also seen in leucoblasts of the same patient. The two types of structures were never seen simultaneously in the same cell. The authors review the literature pertaining to the morphology of virus-like particles associated with malignant hematologic disease.

Cell Nucleolus↗
PubMed1976

Ultrastruct and biochemical chantes in cultured human malignant melanoma cells after heterotransplantation into nude mice.

Cells from three lines of cultured human malignant melanomas were heterotransplanted into nude mice and then recultered. The shape of the cells, the aspect of the melanosomes, and the content of 5-S-cyteinyldopa showed pronounced changes induced by the transplantation. Such results indicate that this experimental model should be used with great caution. A relationship was found between the shape of the melanosomes and the content of 5-S-cysteinyldopa in the cells.

Animals↗