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Biomedical subjects

P Jullien

Publications and source records attributed to P Jullien.

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

31P NMR spectra of rodent and avian fibroblasts transformed by Rous or Kirsten sarcoma viruses.

31P NMR spectra of normal rodent and avian fibroblasts were compared to those of the same cells transformed either by the Rous sarcoma virus (RSV) or by the Kirsten sarcoma virus (Ki-MSV). Under physiological conditions, the spectra of living or perchloric acid extracted chicken embryo fibroblasts, rat cell line FR3T3 and mouse cell line C127 did not differ from those of their counterparts transformed by RSV or Ki-MSV. However, in the case of FR3T3 cells, on shifting from 37 degrees C to 20 degrees C, and particularly if PBS replaced serum growth medium, a different, though transitory, response of the transformed cells was detected. They then showed, within few minutes, a more rapid ATP depletion with accumulation of fructose 1,6-diphosphate (FDP), as compared to normal control cells.

Animals↗
PubMed1986

Beta-transforming growth factor is stored in human blood platelets as a latent high molecular weight complex.

Human blood platelets, the richest known source of beta-transforming Growth Factor extractable under acid conditions, release in neutral extracts (pH 7.2) a latent form of this growth factor with an apparent molecular weight of 400 Kd. This latent form, poorly active on rat NRK-49F indicator cells in soft agar assays can be activated by exposure to acid pH or 8 molar urea. The acid activated beta-Transforming Growth Factor from neutral extracts elutes on Biogel P60, in 1 molar acetic acid, as a broad peak of apparent molecular weight 15-30 Kd, like when this factor is extracted from platelets by the usual acid-ethanol procedure. Moreover, beta-Transforming Growth Factor from both acid activated neutral extracts and from acid-ethanol extracts elutes on reverse phase at 30% acetonitrile. We suggest that beta-Transforming Growth Factor is stored in human blood platelets as a poorly active high molecular weight complex which may be dissociated and activated in appropriate in vivo microenvironments.

Animals↗
PubMed1985

Conversion of a high molecular weight latent beta-TGF from chicken embryo fibroblasts into a low molecular weight active beta-TGF under acidic conditions.

A latent beta-TGF activity is spontaneously released into serum-free culture medium by chicken embryo fibroblasts. Anchorage-independent growth activity measured on NRK-49F indicator cells, of this latent beta-TGF can be revealed by four different treatments: acidification, alkalinisation, exposure to urea, and heating to 100 degrees C for 3 minutes. This lact activating treatment indicates that latent beta-TGF activation in vitro is non-enzymatic. Active beta-TGF exists in a low molecular weight form 16 Kd (apparent) in 1M acetic acid, which elutes on reverse phase (FPLC) between 33-35% acetonitrile. Under neutral conditions only a high molecular weight form excluded on Biogel P60 is observed. This form is poorly active on NRK-49F for anchorage independent growth but can be fully activated by prior acidification. Rechromatography of the latent beta-TGF-containing fractions under acidic conditions converts the high molecular weight form to an apparent 16 Kd active form. We suggest that the high molecular weight form may correspond to a complex of a beta-TGF associated with a carrier or binding protein.

Animals↗
PubMed1985

Further study of beta-TGFs released by virally transformed and non-transformed cells.

Chicken embryo fibroblasts sensitized by ts RSV respond to TGFs present in the media of non-transformed FR3T3 and NRK-4 rat cells and of the same cells transformed by KiMSV or RSV. They also respond to TGFs present in the media of BHK hamster cells transformed by MoMSV, PyV or RSV. Two other indicator rat cell lines, untransformed NRK-4 and FR3T3, sensitized by ts KiMSV, respond to the same TGF-containing media, and this response is increased by exogenous EGF. Normal FR3T3 cells failed to respond to any of the media. The most sensitive target cells were the ts KiMSV-FR3T3 cells at the restrictive temperature (39.5 degrees C). All the media tested on NRK-49F target cells required EGF for their TGF activity which was essentially dependent on prior activation by acidification. These data show that the above media from non-transformed or transformed cells contain beta-TGFs, with no detectable accompanying alpha-TGF activity. The release of and the response to these TGFs are not interdependent. A function of ts mutant src and k-ras viral oncogenes, still expressed at the restrictive temperature, can sensitize non-responsive cells, without there being any specificity towards the TGF producer cells.

Animals↗
PubMed1985

Inhibition of Rous sarcoma virus production by formycin.

The effect of formycin, an adenosine analog, on the growth of chick embryo fibroblasts and on Rous sarcoma virus (RSV) production was studied. An adverse effect on cell proliferation was observed in the presence of 10 microM formycin. Treatment with 5 microM formycin for 24 hr reduced by a factor of about 1000 the yield of infections progeny whereas the cell growth remained unaltered. Moreover the few particles released in the presence of formycin showed a markedly decreased ability to synthesize viral cDNA. This impairment was shown to be related to a nonfunctional primer tRNA.

Animals↗
PubMed1984

Normal embryo fibroblasts release transforming growth factors in a latent form.

Normal chicken, mouse, and human embryo fibroblasts release into their culture media transforming growth factors (TGFs) in a latent form. Their soft agar colony-forming activity on two widely used target cells, rat NRK-49F and mouse AKR-2B, is essentially revealed only after prior acidification of cell-conditioned media. These TGFs are EGF-dependent when assayed on NRK-49F cells and EGF-independent on AKR-2B cells. The TGF activity from the chicken source is released in three (apparent) molecular weight forms of 500 kd, 125 kd, and 20 kd.

Animals↗
PubMed1984

Role of the mitogenic property and kinase activity of p60src in tumor formation by Rous sarcoma virus.

Expression of the src gene of Rous sarcoma virus in chicken embryo neuroretinal cells results in morphological transformation and sustained proliferation of this normally resting cell population. PA101 and PA104 are two mutants of Rous sarcoma virus which induce neuroretinal cell proliferation in the absence of morphological transformation. Their mitogenic property is temperature sensitive, and they both encode p60src proteins with low kinase activity. To study the role of the mitogenic function and protein kinase activity of p60src in tumorigenesis, we investigated the oncogenicity of PA101 and PA104. Both mutants were less tumorigenic than wild-type virus when injected into chicks. Tumorigenicity was further assayed by inoculating infected chicken embryo fibroblasts and neuroretinal cells onto the chorioallantoid membrane of embryonated duck eggs. This system provides a nonpermissive and immunodeficient environment for xenogenic cell grafting and allows the study of cell tumorigenicity within a temperature range of 37 to 39.5 degrees C. Chicken embryo fibroblasts and neuroretinal cells infected with PA101 were as tumorigenic as wild type-infected cells at 37 degrees C, but tumor development was significantly reduced at 39.5 degrees C. In contrast, both cell types infected with PA104 displayed sharply reduced tumorigenicity. Cell cultures derived from PA101 tumors induced on the chorioallantoid membrane were similar to the corresponding cells maintained in vitro in terms of morphology, production of plasminogen activator, relative amounts of phosphotyrosine in total cellular proteins, and phosphorylation of 34,000-molecular-weight protein. These results indicate that the expression of the mitogenic function of src does not account per se for cell tumorigenicity and that tumor formation is compatible with low levels of p60src protein kinase activity.

Animals↗
PubMed1984

Latent beta-transforming growth factor in nontransformed and Kirsten sarcoma virus-transformed normal rat kidney cells, clone 49F.

Normal rat kidney cells of the clone 49F and their Ki-MSV-transformed counterparts spontaneously release the same transforming growth factor (TGF) activity in an inactive form. By acidification followed by neutralization prior to assay, this TGF activity is unmasked and promotes anchorage-independent growth of the NRK-49F indicator cells in the presence of epidermal growth factor. The TGF activity released by both cell types has an apparent molecular weight of 9,000 under acidic conditions, does not compete for binding to epidermal growth factor receptors, is heat resistant but dithiothreitol and trypsin sensitive, and therefore is of the beta-TGF class.

Animals↗
PubMed1982

A ts T mutant of Schmidt Ruppin strain of Rous sarcoma virus restricted at 39.5 degrees C for the morphological transformation and the tumorigenicity of chicken embryo fibroblasts.

In order to investigate a possible correlation between in vitro transformation and tumorigenicity in ovo, a new temperature-sensitive class T mutant of Rous Sarcoma Virus was isolated with a lower (39 degrees 5C) restrictive temperature for morphological transformation. This lower restrictive temperature was compatible with the survival of chicken and duck eggs for the tumorigenicity studies. In chicken embryo fibroblasts (CEF) infected by this new mutant, PA 17, and cultured at 39 degrees 5C, increase of hexose uptake, plasminogen activator production and anchorage-independent growth were only partially restricted, requiring incubation at 41 degrees 5C for a complete shut-off. Tumorigenicity in chicken and duck eggs inoculated with CEF infected and transformed by PA 17 was restricted at 39 degrees 5C, correlating well with the restriction of morphological transformation at this temperature. The kinase activity of the transforming protein pp60src in lysates of PA 17 infected cells cultured at permissive or restrictive temperatures was labile in RIPA buffer, as in the case of some previously examined ts T mutants. In the non-ionic detergent NP40 buffer, the kinase activity of PA17 infected cell lysates was better conserved and showed a moderate temperature dependence. These results suggest that, in spite of the correlations between the transformed cell phenotype in vitro and cell tumorigenicity in ovo, it is difficult to establish a quantitative relationship.

Allantois↗
PubMed1982

Cells transformed by Rous sarcoma virus release transforming growth factors.

Chicken embryo fibroblasts and hamster BHK cells transformed by Rous sarcoma virus (RSV) release in their culture media growth factors which enhance markedly anchorage-independent colony formation in gelified medium, at the restrictive temperature (41 degrees 5 C), of chicken embryo fibroblasts (CEF) infected by RSV mutants with a ts mutation of the src gene. This action is not observed with uninfected CEF, and, therefore, appears to require some expression of the viral src gene in the target cells. The enhancing factors are proteins related to the family of the transforming growth factors (TGFs) by their molecular weight (about 20 kd), their heat and acid resistance, and their sensitivity to dithiothreitol. They do not compete with 125I EGF for binding on the EGF receptors of the membrane of A431 cells. As chicken embryo fibroblasts are devoid of EGF receptors, their activity is not potentiated by EGF.

Animals↗
PubMed1982

Differential uptake of 2-fluoro-2-deoxyglucose by normal and transformed chicken and mouse fibroblasts as a function of glucose concentration.

Recently, [18F]-2-fluorodeoxyglucose, a positron emitter, has found an important application in certain metabolic studies using external scanning techniques. We have studied [14C]-2-fluorodeoxyglucose, [3H]-2-deoxyglucose and [14C]-D-glucose uptake in normal and transformed chicken and mouse fibroblasts to determine whether such external scanning techniques might be applicable to detect in vivo tumoral localisations. In this in vitro model, with glucose concentrations in the culture medium below that of normal animal blood, transformed cells showed a higher uptake of all three hexose tracers than did normal cells. However, at physiological glucose concentrations there was no differential uptake of these hexoses. Therefore our results suggest that [18F]-fluorodeoxy-glucose would be of no help in the in vivo detection of tumour localisations by external positron scanning unless in vitro and in vivo cell behavior differs considerably.

Animals↗
PubMed1980

Hexose uptake enhancing factor released from Rous sarcoma cells.

Conditioned media from Rous sarcoma virus transformed chicken embryo fibroblasts stimulate the uptake of 2-deoxyglucose in normal chicken fibroblasts. The factor responsible for this effect, which is also shed in very low amount by non-transformed fibroblasts, is destroyed by trypsin and not linked to the protease and plasminogen activator activities present in the media. Its apparent molecular weight, determined by gel filtration, is about 20,000 daltons. The factor released by transformed cells might be related to the monomeric form of a family of glucose binding and transport proteins recently reported by Lee and Lipmann ('78) to be detached by detergents from normal and transformed cells.

Animals↗
PubMed1979

[Serological diagnosis of Staphylococcus aureus infections using anti-A beta teichoic acid antibodies assay (author's transl)].

225 control subjects, 12 hospitalized Staphylococcus free (34 sera) and 16 S. aureus infected patients (79 sera) were tested for anti-A beta teichoic acid antibodies, using counter-immunoelectrophoresis. Anti-alpha and gamma haemolysins antibodies were dosed in parallel in 164 sera. Less than 5 per cent of control sera (3,11 per cent) have an antibody tire higher than 1/8: this tire is therefore selected as threshold level of positivity. Ten of the 12 hospitalized patients without staphylococcal infections are below this level. 31,6 per cent of staphylococcus infected patients have higher serum titers; only 3,7 per cent have no antibodies. In the others, a significant rise in titres is observed. There is no correlation between anti-alpha and gamma staphylolysin and anti-teichoic acid antibodies titres. The method suggested, both easy and rapid, could be used in association with anti-staphylolysin dosage for serological diagnosis of staphylococcal infections.

Antibodies, Bacterial↗
PubMed1977

Growth stimulation of sparse, serum deprived and of confluent, contact inhibited mammalian fibroblasts by a preparation of 3':5'-cyclic AMP phosphodiesterase.

Resting mammalian fibroblasts, either sparse and maintained in a serum-free medium, or confluent and contact inhibited, are stimulated to divide by treatment with a preparation of 3':5'-cyclic AMP phosphodiesterase. This enzyme preparation contained a low level of trypsin-like and alpha-chymotrypsin-like activity, but its effect on cell growth could not be mimicked by pure, crystallized trypsin and alpha-chymotrypsin at concentration equivalent to their contamination in the above preparation. Preincubation of the 3':5'-cyclic AMP phosphodiesterase preparation with the protease inhibitor, phenyl methane sulfonyl fulride, did not affect, either, its stimulation of DNA synthesis in fibroblasts, or its enzymatic hydrolysis of cyclic AMP.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1976

Viable hybrids between lethally X-irradiated hamster cells and unirradiated mouse cells.

Sendaï-virus-induced fusion between heavily X-irradiated hamster cells, BHK21 or RS2-3 (BHK21 cells transformed by Rous Sarcoma Virus), and unirradiated mouse cells, A9 or c11D, give rise to hybrids. These hybrids possess mouse and hamster surface antigens. However, RS2-3 x mouse hybrids do not form heterokaryons with chick-embryo fibroblasts producing infectious Rous sarcoma virus.

Animals↗