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Biomedical subjects

R Monier

Publications and source records attributed to R Monier.

At least 37 records · Page 2Linked to original sources
PubMed1986

Modulation of c-fos and c-myc mRNA levels in normal human lymphocytes by calcium ionophore A23187 and phorbol ester.

A transient expression of the proto-oncogenes c-fos and c-myc is rapidly induced by growth factors or mitogens in different cell types including lectin-stimulated lymphocytes. To elucidate the early events of lymphocyte activation, we determined (by Northern blot analysis) the steady-state levels of c-fos and c-myc mRNA in normal human peripheral blood lymphocytes (PBL) stimulated with the Ca2+ ionophore A23187 and/or 12-O-tetradecanoylphorbol-13-acetate (TPA), whose biological activities are well defined. We report that ionophore A23187 (0.5 microM) or, to a significantly lesser extent, TPA (0.5 ng/ml), neither of which is mitogenic alone at these concentrations, nevertheless can induce a transient accumulation of the proto-oncogene transcripts. These results indicate that a significant accumulation of c-fos and c-myc mRNA can occur without subsequent lymphocyte proliferation. The combination of these two mitogens increases the induced levels of both types of c-onc mRNAs. The level of mRNA accumulation correlates with the degree of proliferation induced by mitogenic combinations of ionophore A23187 and TPA, as measured by [3H]thymidine incorporation. Thus, these compounds act synergistically both with respect to c-fos and c-myc mRNA accumulation and to mitogenicity in human PBL. We also studied the level of c-fos transcripts following stimulation of the T lymphocyte T3/Ti receptor complex, using monoclonal anti-T3 antibodies. We observed that mitogenic doses of anti-T3 also induce an accumulation of c-fos mRNA, whose induction also is synergized by TPA. These results suggest that transient accumulation of c-fos; as well as c-myc, mRNA is a normal event of the immune response. They confirm that Ca2+ ionophore combined with TPA can mimic some molecular features of the early steps of normal human PBL activation.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1985

Increased level of amplification of the c-myc oncogene in tumors induced in nude mice by a human breast carcinoma cell line.

Cell line SW 613-S, derived from a human breast carcinoma, contained double minute chromosomes (DMs) but lost them progressively upon in vitro cultivation. These cells were tumorigenic in nude mice. Cell lines were derived from the tumors and were found to have a high DM content. In three such cell lines, DMs were stably maintained upon in vitro cultivation, whereas in another they were progressively lost. We found that the c-myc oncogene is amplified 5- to 10-fold in SW 613-S and 20- to 90-fold in the different cell lines derived from the tumors. At least part of the additional c-myc copies were found associated with a purified DM fraction. In cell lines which lost the DMs during in vitro passages, the level of amplification was maintained. In situ hybridization experiments indicated that this loss was compensated by the acquisition of copies of the c-myc gene integrated into a chromosome. No major rearrangement of the amplified c-myc gene was detected. The amount of c-myc messenger RNAs is roughly proportional to the level of amplification. Our results indicate that growth of SW 613-S cells as tumors in nude mice selected cells with an increased level of amplification and expression of the c-myc oncogene.

Animals↗
PubMed1982

Effect of tumor promoters on soft-agar growth of Swiss 3T3 cells infected with SV40 tsA mutants.

The availability of many SV40 mutants, in which the ability of the virus to transform fibroblasts is variously affected, has prompted us to investigate the effect of treating SV40-infected cells with known tumor promoters on the expression of the transformed phenotype. Using mouse Swiss 3T3 cells and various SV40 tsA mutants unable to transform these cells at 39 degrees C, we have observed a dramatic effect of the potent phorbol ester promoter, 12-O-tetradecanoyl-phorbol-13-acetate, on the formation of macroscopic colonies in soft-agar at the restrictive temperature of 39 degrees C. The efficiency of other phorbol esters and various substances such as anthralin, saccharin, sodium cyclamate, mellitin, griseofulvin and benzoyl peroxide, was in agreement with their reported promoting activities suggesting that mouse Swiss 3T3 cells infected with SV40 tsA mutants could provide a quick and easy test to detect promoters.

Agar↗
PubMed1982

Cell transformation by simian virus 40 mutants.

The role played by the early region of simian virus 40 (SV40) in cellular transformation has been investigated using a series of constructed double mutants which associated a d1-54-59 mutation with either a tsA mutation or a deletion located in the 3'-terminal part of the A gene. The ability of secondary mouse or rat embryo infected cells to clone at low cell density was used to select transformants, which were later tested for anchorage-independent growth. The results show that the conversion of a mouse or rat embryo cell into a continuous cell line requires the permanent expression of the A gene. SV40 mutants were also used in conjunction with tumor promoters to induce anchorage-independent growth of Swiss 3T3 cells. SV40-tsA-infected cells produced macrocolonies when plated in soft-agar at the restrictive temperature of 39 degrees C in the presence of the potent tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA). At the permissive temperature of 33 degrees C, TPA increased the number of soft-agar clones about 4-fold. A good correlation between the formation of macrocolonies at 39 degrees C and the reported promoting activity of various compounds, including teleocidin B and anthralin, was observed. Saccharin behaved in this system as a weak promoter, since an effect is observed at concentrations around 1 X 10(-4) M, while the effect of TPA is clearly detected at 1.6 X 10(-10) M. The results suggest that SV40-tsA-infected Swiss 3T3 cells might provide a quick and easy test for tumor promoters.

Animals↗
PubMed1981

Mapping of the viral mRNA encoding a super-T antigen of 115,000 daltons expressed in simian virus 40-transformed rat cell lines.

Simian virus 40-transformed V11 F1 clone 1 subclone 7 rat cells produced a considerable amount of an elongated form of large-T antigen with an Mr of 115,000 (115K super-T antigen), but these cells did not produce detectable traces of normal-sized large-T antigen (86,000 daltons) (P. May, M. Kress, M. Lange, and E. May, Cold Spring Harbor Symp. Quant. Biol. 44:189-200, 1980). First, a comparison of the tryptic peptide fingerprints of 115K super-T and large-T antigens suggested that 115K super-T antigen is simian virus 40 coded and contains a duplication of amino acid sequences of large-T antigen. Second, from S1 mapping analysis of 115K super-T mRNA, performed with various restriction fragments of simian virus 40 DNA, it was concluded that super-T mRNA is a form of large-T mRNA containing a tandem duplication of the sequence extending from approximately 0.46 to 0.35 map unit. The duplicated sequence corresponded to that region of the simian virus 40 genome in which 12 of 13 tsA mutation sites are clustered (C. J. Lai and D. Nathans, Virology 66:70-81, 1975).

Animals↗
PubMed1979

Oncogenic transformation of rat lung epitheloid cells by SV 40 DNA and restriction enzyme fragments.

Rat epitheloid lung cells were transformed with various preparations of SV40 dna using the Ca2+-precipitation technique. The amount of SV40 genetic information integrated into transformed clones was evaluated by DNA-DNA renaturation kinetics. The growth properties on plastic and in soft-agar were examined, as well as the ability to induce tumors in syngeneic new-born animals or in adult nude mice. One particular transformed line, which had received the Hpa II/BamH I A (59 per cent) fragment, was found to contain about 3 integrated copies of this fragment per cell and no significant amount of the Hpa II/BamH I B (41 per cent) fragment. This line which grew to high saturation densities and efficiently formed clones in low serum on plastic, produced tumors in both syngeneic rats and nude mice. Thus the Hpa II/BamH I A fragment, which mainly includes early viral information, was sufficient to impart these properties to rat epitheloid lung cells.

Animals↗
PubMed1978

Viable deletion mutants in the simian virus 40 early region.

For the purpose of isolating hr-t-like mutants of simian virus 40, we have constructed variants that have lost the unique site for the restriction enzyme Taq I at 0.565. Five mutants have been isolated and characterized by restriction enzyme analysis. All of them produce a normal size T antigen. Four produce a t antigen reduced in size as well as in amount; the fifth one does not seem to make any t antigen at all. The ability of these mutants to transform mouse cells in vitro, as tested by anchorage dependence, is clearly altered; however, the defect is only partial. In the same test, the mutants can complement a tsA mutant for transformation and therefore define a second complementation group in the simian virus 40 early region.

Antigens, Viral↗
PubMed1978

Presence of free viral DNA in simian virus 40-transformed nonproducer cells.

Extracts from several simian virus 40 (SV40)-transformed nonproducer cells were prepared by the hot-phenol procedure normally used to extract cellular RNA. These extracts contained SV40 infectious units. Part of the infectious units were identified as SV40 form I DNA molecules. The results of reconstruction experiments suggest that SV40 form I DNA is extractable by the hot-phenol procedure because of its fast renaturation rate. The significance of the presence of free viral DNA in nonproducer transformed cells is discussed.

Animals↗
PubMed1975

[Neuroskeletal radiography and relationships of the sensitive branch of the radial nerve].

The authors carried out an anatomical, roentgenological and surgical study of the ramus superficialis of the radial nerve in man. This branch springs down 1,2 cm. below the humeroradial space and crosses the posterior rim of brachioradialis 8 cm. above the tip of the radial processus styloideus. Twice the exceptional arteria antebrachialis dorsalis was found; the vessel and the radial nerve looked like a posterior pedicle at the forearm. Among the 3 ending branches, the middle one is the most vulnerable in lateral approach of radius and naviculare.

Fetus↗