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F Besançon

Publications and source records attributed to F Besançon.

14 recordsLinked to original sources
PubMed1992

Post-transcriptional regulation of transferrin receptor mRNA by IFN gamma.

IFN gamma inhibits the rise in transferrin receptor mRNA level which is normally observed when stationary WISH cells are stimulated to proliferate. This effect is not attributable to a change in the transcription rate of the transferrin receptor gene or in the cytoplasmic stability of the mRNA. The IFN gamma-induced reduction of the transferrin receptor mRNA content is already present at the nuclear level to an extent comparable to that observed in whole cells. Thus, IFN gamma does not impair the passage of this mRNA from the nuclear to the cytoplasmic compartment but probably interferes with a nuclear post-transcriptional event during the processing of the immature transferrin receptor mRNA. Two different levels of regulation of transferrin receptor mRNA have been previously reported. Iron modulates the cytoplasmic stability of this mRNA through the binding of a specific cytoplasmic factor, whereas cell growth variation influences the transcription of this gene. Our results suggest the existence of another mechanism of regulation for transferrin receptor gene expression not so far considered. Furthermore, the distinction between the mechanism of regulation exerted by IFN gamma and that exerted by cell proliferation on transferrin receptor gene expression suggests that, in WISH cells, the IFN-induced transferrin receptor decay is not a consequence of cell growth arrest but rather one of the causes of the antiproliferative effect of IFN through iron deprivation.

Blotting, Northern↗
PubMed1991

Direct induction of interferon-gamma- and interferon-alpha/beta-inducible genes by double-stranded RNA.

Using Northern analysis, we here show that the inducibility by double-stranded (ds) RNA of interferon-alpha/beta-inducible genes is not restricted to a few genes but extends to all the genes known to be stimulated by IFN type I in fibroblasts. Moreover, we show that some genes, preferentially regulated by IFN-gamma, are also activated by dsRNA. We present a series of arguments demonstrating that the induction by dsRNA is not mediated by IFN. In addition to the fact that this induction occurs in the presence of cycloheximide and/or anti-IFN-alpha/beta antibodies in fibroblasts, we observed that, in IFN-resistant Daudi cells, ISG15 and IP-10 genes which are not induced by IFN-beta, are still inducible by dsRNA. dsRNA is also still active on 2-5 AS and ISG15 genes in cells carrying homozygous deletions of IFN alpha/beta genes. Actinomycin D experiments and nuclear in vitro elongation assays reveal that the induction by dsRNA involves, as its early step, a transcriptional event. This induction was found not to require protein synthesis, suggesting that activation of preexisting cellular factors is involved. The opposite inducibility by dsRNA of IFN-beta and 2',5'-oligoadenylate (2-5A) synthetase genes in serum-deprived fibroblasts indicates that pathways of induction by dsRNA of these two genes are not identical. Inhibition by 2-aminopurine of the induction of IFN-inducible mRNAs by IFN-beta or dsRNA suggests the participation of a protein kinase in their mechanism of action.

2-Aminopurine↗
PubMed1991

[Role of percutaneous endoscopic gastrostomy in amyotrophic lateral sclerosis].

Percutaneous endoscopic gastrostomy (PEG) is an enteral nutritional assistance technique using a simple device compatible with conventional feeding and thus enabling the patient to be integrated into his or her social and familial surroundings. This inexpensive device is quickly and easily inserted under local anaesthesia. It causes little morbidity and virtually no mortality and has many advantages for patients with amyotrophic lateral sclerosis (ALS). We report the results of PEG in 28 ALS patients with bulbar involvement. Three of these patients developed minor complications during 6 consecutive months of PEG-assisted nutrition (2 had periostomial infection, 1 had mild haematemesis). There were no major complications, and mortality directly ascribable to PEG was nil. All patients put on weight or had their weight stabilized, and GEP was well accepted in all cases.

Adult↗
PubMed1990

Tumour necrosis factor enhances induction by beta-interferon of a ubiquitin cross-reactive protein.

Tumour necrosis factor alpha (TNF-alpha) elicited an antiviral response in some cell lines (MG-63 and HEp-2) but not in others (MDBK). Cell lines that generated an antiviral response to TNF-alpha also showed induction of a 15K protein which shared sequence homology with ubiquitin and reacted with an antibody to ubiquitin. This ubiquitin cross-reactive protein (UCRP) had been demonstrated previously to be induced by interferon. The TNF-alpha induction of UCRP occurred at the level of transcription. TNF-alpha induction of both the antiviral state and the 15K protein was blocked by either monoclonal or polyclonal anti-beta-interferon (IFN-beta) antibody. However no measurable increase in the mRNA specific for IFN-beta was detected after TNF-alpha treatment. Nonetheless, in supernatants from cell cultures, the presence of an antiviral activity inhibitable by anti-IFN-beta antibody indicates that these cells are making IFN-beta already. We conclude that the TNF-alpha induction of antiviral activity and UCRP in cells is dependent upon the presence of constitutive low levels of IFN-beta in the responding cells. Furthermore TNF functions to enhance the existing IFN-beta activity.

Cross Reactions↗
PubMed1977

Membrane receptors for interferon.

Specific cell membrane receptors for interferon have been postulated based on a variety of different observations, such as the following: trypsin treatment of monkey-mouse hybrid cells preferentially destroys sensitivity to primate interferon (9); syngeneic mice immunized with human-mouse hybrid cells develop surface-directed antibodies, which only block antiviral action of human interferon (24); interferon covalently bound to Sepharose beads retains its antiviral activity despite the fact that diameters of the beads are several times those of the cells (1,10,19); cells challenged with polyl:C to produce interferon do not develop resistance to viral infection in the presence of interferon antiserum (30). Interferon has a strong and specific affinity for the carbohydrate side chain of cell membrane gangliosides. Preincubation of Sepharose-bound interferon with gangliosides inhibits antiviral activity in the following order of potency: GM2 greater than or equal to GTl greater than GMl greater than or equal to GDla (3). Derivatives of GM2 lacking either terminal N-acetyl-galactosamine or terminal N-acetyl-neuraminic acid are not (or very little) inhibitory; in addition, binding to gangliosides is reversed by N-acetyl-neuraminyl-lactose, the trisaccharide common to all gangliosides. These data clearly demonstrate interferon's specificity for the carbohydrate moiety of the ganglioside molecule (6). Phaeseolus vulgaris lectin, which blocks antiviral action of interferon (4), also prevents binding of interferon to ganglioside-Sepharose affinity columns (2). Many substances of known affinity for gangliosides likewise inhibit action of interferon. These include cholera (15) and tetanus toxins (2), thyrotropin (5,23) and human chorionic gonadotropin (5). Although a more general effect on the state of the membrane or on cellular metabolism by these substances cannot be ruled out, competition for interferon binding sites appears to be the most plausible explanation. Increased sensitivity of certain transformed cells to interferon upon uptake of exogenous gangliosides not only supports the concept that these glycolipids are involved in binding of interferon to the membrane, but furthermore points to the importance of interferon-ganglioside interaction for triggering of the antiviral response (29).

Cell Membrane↗
PubMed1977

[Trial of immunodiffusion on cellulose acetate. Application to the estimation of immunoglobulins A and serum transferrin. Results in alcoholism and cirrhosis (author's transl)].

The authors propose electro-immunodiffusion on cellulose acetate instead of agar gel. This simple, rapid and economical method was applied to the estimation of serum immunoglobulins A and transferrin. The following results were obtained for the IgA/transferrin ratio in 108 cases: Normal: 0.87 +/- 0.29; alcoholics without proved cirrhosis: 1.61 +/- 0.95; alcoholic cirrhosis: 3.36 +/- 2.30. The interest of this determination in detection is increased by this simple test.

Acetates↗
PubMedDate not supplied

Gallstone formation.

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Animals↗