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Biomedical subjects

J F Nicolas

Publications and source records attributed to J F Nicolas.

At least 181 records · Page 10Linked to original sources
PubMed1984

5-Azacytidine is able to induce the conversion of teratocarcinoma-derived mesenchymal cells into epithelia cells.

The inhibitor of DNA-methylation, 5-azacytidine (5- AzaC ) induced the appearance of cytokeratin-containing cells in several mesenchymal cell lines such as teratocarcinoma-derived fibroblasts, preadipocytes and myoblasts, NIH-3T3 fibroblasts and human embryonic fibroblasts. At optimal 5- AzaC concentrations the proportion of such cells was in the range of 10(-1) compared with 10(-6) -10(-4) in non-treated cultures. Dose-response curves indicated that the induction of cytokeratin was the result of an interaction of the drug with few targets. Stable, mature, keratinocyte cell lines, as well as lines of myoblasts and astrocytes, could be isolated from a teratocarcinoma-derived preadipocyte line, showing that 5- AzaC is able to provoke a wide range of complete phenotypic conversions. In these cell lines, the intermediate filaments corresponded to the morphological phenotype. Altogether, the results suggest that 5- AzaC preferentially activates certain genes.

Adipose Tissue↗
PubMed1984

Construction of a retrovirus capable of transducing and expressing genes in multipotential embryonic cells.

Retroviral gene expression is inhibited in embryonal carcinoma (EC) cells. We have constructed a recombinant retroviral vector that is capable of expressing the neomycin-resistance (neo) gene in EC cells. The critical modification that permits expression of the neo gene is the insertion of a composite simian virus 40 early gene-herpes simplex virus type 1 thymidine kinase gene (SVtk) promoter 3' to the viral first intron and 5' to the neo gene. When the SVtk promoter is deleted, the recombinant retrovirus is either unable or extremely inefficient at expressing the neo gene in EC cells.

Drug Resistance↗
PubMed1984

[Nonsense RNA: a tool for specifically inhibiting the expression of a gene in vivo].

We describe a general technique to inhibit gene expression in eukaryotic cells. The gene we chose to inhibit was the E. coli LacZ gene (encoding beta-galactosidase), which has previously been cloned into a eukaryotic expression vector [1]. This plasmid is called pCH110. We constructed a variant of pCH110 in which we flipped a 2566 base pair 5' fragment of the LacZ gene into the antiparallel orientation. The plasmid containing this mutated LacZ gene is called pNSLacZ (NS signifies non-sense coding sequence). When equal amounts of pCH110 and pNSLacZ are co-transfected into 3T6 mouse fibroblasts, the beta-galactosidase activity is decreased by approximately a factor of ten. Increasing the ratio of pNSLacZ to pCH110 above 1:1 does not appreciably increase the level of inhibition. Next, we prove the specificity of the inhibition by adding a third gene to the transfection mixture. For this purpose, we used pSVneo beta, a plasmid which expresses a phosphotransferase. We found that even when the beta-galactosidase activity was diminished by a factor of 10, the phosphotransferase activity was unaffected. Therefore, we have demonstrated that: the presence of an antiparallel copy of the LacZ gene results in a significant and specific diminution of the LacZ gene's expression; only a fraction of the LacZ gene needs to be in the antiparallel orientation in order to observe this effect. These results suggest that this technique can serve as a tool to decrease the level of gene expression in order to study the function of specific genes, or as a therapeutic manoeuvre in the treatment of disorders of abnormal gene expression.

Animals↗
PubMed1983

Therapeutic use of TP5 (thymopoietin 32-36) in sarcoidosis of the skin.

TP5, a synthetic pentapeptide corresponding to thymopoietin 32-36, was administered alone to eight adult volunteer patients with sarcoidosis. A dose of 50 mg of TP5 was given iv, three times a week for 6 weeks, to three patients with erythema nodosum (EN) and bilateral hilar adenopathy, and to one patient with sarcoids of the skin; and for 12 weeks, to the other four patients with skin sarcoids. Before treatment and every 3 weeks thereafter clinical features; routine laboratory tests; tests for cellular immunity, humoral immunity, and auto immunity; IgE levels; and polymorphonuclear functions were recorded. EN disappeared in 3 weeks; hilar adenopathy improved or disappeared more slowly. Improvement of skin sarcoids was noted (lesions flattened or were cured). No side effects were observed. No evident changes in routine tests, humoral and auto immunity, IgE levels, and functions of polymorphonuclear leukocytes were observed. Cutaneous anergy to skin multi-tests was observed in seven patients before treatment, and was corrected with TP5 in six cases. In patients with low levels of peripheral blood T cells and suppressor T cells (as determined using specific monoclonal antibodies), a progressive normalization was obtained with TP5. These data support the efficacy of TP5 in sarcoidosis, although the action of the drug may be only temporary, as spontaneous remission may have occurred in this open trial of only eight cases.

Adult↗
PubMed1982

Numeration of T cell subsets in sarcoidosis using monoclonal antibodies: decreased levels of peripheral blood T cells and cells with suppressor T cell phenotype.

Peripheral blood lymphocytes frm 16 patients with sarcoidosis (9 patients with skin sarcoids, 7 patients with erythema nodosum and bilateral hilar adenopathy) and cutaneous anergy and from 23 age-matched healthy controls were characterized by reactivity with monoclonal antibodies OKT3, OKT4, OKT8 directed to surface antigens of T lymphocytes, helper-inducer and suppressor-cytotoxic T cell subsets, respectively. In contrast to healthy controls, patients with sarcoidosis had reduced percentages of OKT3+, OKT4+ and OKT8+ cells and a major decrease in the OKT8+ (suppressor) subset. However, these changes were significant only in the group of patients with acute sarcoidosis (erythema nodosum). This abnormal T cell distribution correlates with the alterations in cell-mediated immunity previously observed and suggests the presence of a defective circulating suppressor T cell activity in acute sarcoidosis.

Adult↗
PubMed1981

Differentiation of a teratocarcinoma line: preferential development of cholinergic neurons.

A line of embryonal carcinoma cells, PCC7-S, established in vitro from a spontaneous testicular teratocarcinoma, has been studied. Upon removing the cells from a low density monolayer culture system and permitting the cells to form aggregates in suspension, we observed a change of several physical and biochemical parameters: (a) reduction in average cell volume, (b) blockage and accumulation of cells in G1, (c) rise in secreted protease activity, (d) rise in acetylcholinesterase and choline acetyltransferase activities, and (e) disappearance of embryonic antigen F9. Although PCC7 aggregates did not undergo substantial morphological changes while suspended, when aggregates 4 or more days old were allowed to attach to plastic tissue culture dishes, substantial neurite outgrowth occurred over the next 1-3 d. This process was markedly enhanced by the addition to the growth medium of carboxymethylcellulose and inhibitors of DNA synthesis. Transmission electron microscopy disclosed a neurite ultrastructure consistent with that of neuronal processes. A veratridine-stimulated, tetrodotoxin-blocked sodium influx of 100 nmol/min per mg protein was also observed in these differentiated surface cultures. This cell line is discussed in terms of its utility for the study of early events leading to a commitment to cellular differentiation, as well as for the investigation of terminal differentiation to cholinergic neurons.

Acetylcholinesterase↗
PubMed1980

Bone-forming cell line derived from embryonal carcinoma cells.

The use of established cell lines of various types has provided information on the properties of certain stem cells and on the conditions of their differentiation. No bone-forming cell line has so far been described. We report here the isolation, from in vitro differentiating teratocarcinoma cells, of a line which, on subcutaneous injection into syngeneic mice, gives rise to ossicles. The appearance of ossicles is preceded by the formation of a cartilaginous matrix, thus reproducing what has been described as endochondral differentiation. The ossicles obtained are rapidly colonized by host marrow, are non-malignant and stop growing 2 weeks after injection of the cells. In certain conditions, however, osteosarcomas, chondroosteosarcomas and fibrosarcomas can be obtained. From these tumours, cell lines have been isolated which retain in vitro the properties of the cells found in the tumour.

Animals↗
PubMed1979

Junctional modulation in mouse embryonal carcinoma cells by Fab fragments of rabbit anti-embryonal carcinoma cell serum.

Mouse embryonal carcinoma PCC4 cells are connected by extensive gap and tight junctions. When the cells are incubated in a medium containing Fab fragments against embryonal carcinoma F9 cells, they round up and a process of junctional removal is initiated. In particular, gap junctions are internalized and after 30 hr of incubation with the anti-F9 Fab fragments both tight and gap junctions are no longer present at the cell surface; however, the cells are still in contact by means of small attachment sites.

Animals↗
PubMed1978

Carbohydrate structure and cell differentitation: unique properties of fucosyl-glycopeptides isolated from embryonal carcinoma cells.

From embryonal carcinoma cells labeled with fucose, two main classes of glycopeptide products of Pronase digestion can be distinguished by Sephadex G-50 column chromatography: one eluted near the excluded volume and a smaller one. The large fucosyl-glycopeptides are scarcely present in differentiated cells derived from embryonal carcinoma cells (i.e., fibroblastlike cells, myoblasts, and parietal yolk-sac carcinoma). During in vitro differentiation of embryonal carcinoma cells, these large glycopeptides disappear almost completely. The small glycopeptides were analyzed by paper electrophoresis, concanavalin A-Sepharose affinity chromatography, and digestion with an endoglycosidase. The major components of these glycopeptides from embryonal carcinoma cells appear to be different from complex glycopeptides known to occur in adult cells. The glycopeptide pattern of mouse preimplantation embryos resembles that of embryonal carcinoma cells. These results suggest that the carbohydrate profile changes fundamentally during early stages of mammalian development.

Cell Differentiation↗
PubMed1978

Metabolic cooperation between mouse embryonal carcinoma cells and their differentiated derivatives.

Metabolic cooperation has been used as an index of intercellular communication between mouse embryonal carcinoma (EC) and other cell types. EC cells do not cooperate with differentiated cells of various properties or origins. In contrast they cooperate with cells of all other EC lines tested, including a human teratocarcinoma line, but with different efficiencies. This might reflect differences either in cell-cell interactions or in the formation of gap junctions. During in vitro differentiation, EC cells appear to remain isolated from differentiated cell types.

Cell Adhesion↗
PubMed1977

Blood formation in a clonal cell line of mouse teratocarcinoma.

Pluripotent cells of a teratocarcinoma clonal line differentiate into various tissues when they are cultivated in submerged cultures. We describe here the formation of endodermal vesicles and blood islands in organotypic cultures of such cells. These are the first macroscopically visible tissues to appear in organ culture and they give rise to megalocytes, the ultimate stage of blood cell evolution in the normal mouse embryo yolk-sac. As in the normal embryo yolk-sac, the formation of haemoglobin-containing cells stops after a while, but it is not replaced by adult haemopoiesis in culture.

Cell Differentiation↗