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J L Tayot

Publications and source records attributed to J L Tayot.

36 records · Page 2Linked to original sources
PubMed1987

[Human placental tissue: a source of natural hematopoietic regulators].

In this paper, it has been shown that human placental tissular extracts are a potent source of natural haemopoietic growth factors. The colony-stimulating activities (CSA) recovered by extraction from washed placental pulp were active both on human and murine haemopoietic progenitors, from monocytic and granulocytic lineages. Crude tissular extracts contained CSA titers at least ten fold the titers usually found in placenta culture media. Placenta is the only human tissue easily available for the study of natural tissue-bound haemopoietic regulators. Extraction on an industrial scale, as proposed for the first time in this paper, should also benefit the identification and purification of new minor molecular classes of growth and maturation factors or inhibitors involved in human haemopoiesis.

Animals↗
PubMed1985

Interaction of solid-phase gangliosides with tetanus toxin and toxoid.

Tetanus toxin has been fractionated on a column of silica beads coated with a ganglioside mixture. Toxicity and affinity of the fractions for brain membranes increased with their affinity for the column. The toxicity recovered with the nonabsorbed fraction was less than 5% with respect to the unfractionated toxin or its firmly bound moiety. Tetanus toxoid yielded less toxic or nontoxic fractions with different affinities for the column. Accordingly, binding of tetanus toxoid to brain membranes was partially preserved under mild toxoiding with formaldehyde. It is concluded that binding to gangliosides is a necessary, but not a sufficient, precondition for the pharmacological activity of tetanus toxin and its derivatives.

Animals↗
PubMed1984

Affinity chromatographic purification and characterization of two iodinated tetanus toxin fractions exhibiting different binding properties.

Highly purified iodinated tetanus toxin preparations separate on ganglioside affinity columns into two distinct (A and B) fractions representing about 20% and 75% of the iodinated toxin, respectively. Fraction A, eluted by 1% NaCl, migrates like native tetanus toxin (150,000 mol. wt) on SDS polyacrylamide gel electrophoresis. It forms an aggregate of molecular weight approximately 360,000 on Sephacryl S-300 gel permeation chromatography in the presence of detergent and contains two isoforms on preparative chromatofocusing. Fraction A binds poorly to neurons in tissue culture or to synaptosomal membrane preparations. It retains, however, its antigenicity and biotoxicity. Fraction B, eluted by 6% NaCl, binds effectively to gangliosides and also to neurons or synaptosome preparations. It has a similar molecular weight and chain composition to the native toxin and displays two isoforms, precipitable during chromatofocusing. Fraction B possesses similar binding, immunological and toxic properties to the original iodinated tetanus toxin. Following excessive iodination (4-6 mCi/mg protein), toxicity can be remarkably reduced. Unlabeled toxin shows a similar chromatographic pattern to the iodinated toxin on affinity columns, suggesting that a large portion (30% by protein and 55% by toxicity) of the toxin has a poor affinity for gangliosides. The molecular pharmacokinetics of tetanus toxin with respect to affinity toward ganglioside-dependent and ganglioside-independent receptors needs re-evaluation.

Animals↗
PubMed1984

Characterization of a human placental factor which inhibits specific binding of phorbol esters to cultured cells.

Phorbol ester receptors have been demonstrated in a variety of cells and tissues using [3H]phorbol-12,13-dibutyrate (PDBu) as a ligand. In a search for possible endogenous ligand(s) for the receptor, we used the human placenta as a source. A factor that can inhibit the binding of [3H]PDBu on different types of cells was purified (133-fold) from an extract of human placenta. This factor, PEBIF ('phorbol ester binding inhibitory factor'), is sensitive to pepsin and resistant to trypsin treatment. It is heat- and acid (pH3)-stable and can be precipitated by 80% ethanol with no loss of activity. PEBIF inhibits binding whether it is added before or after incubation of [3H]PDBu with human amniotic membrane cells (FL). Inhibition occurs at both 37 degrees C and 4 degrees C and is rapid and reversible; it does not require intact cells, since it also occurs with membrane fractions. PEBIF does not act like a binding protein for PDBu, and the kinetics of the inhibition on FL cells is non-competitive. Inhibition was also observed in rat liver cells (IAR 6) and Friend erythroleukaemia cells (FELC). Differentiation of FELC induced by hexamethylene bisacetamide can be inhibited by 12-O-tetradecanoyl-phorbol-13-acetate (TPA) only if TPA-sensitive cells (TS 19-101) are used; no inhibition is observed with TPA-resistant cells (TR 19-9). The same is true of PEBIF. It has been shown that these two clones have about the same number of receptors, with no change of affinity; and the extent of inhibition of PDBu binding by PEBIF was similar in the two clones. Like TPA, PEBIF can increase 2-deoxyglucose uptake in mouse fibroblasts (BALB/3T3 cells). These data suggest that this physiological factor may play a role in the regulation of cell differentiation and/or in the modulation of carcinogenesis.

Biological Transport↗
PubMed1984

A phorbol ester-binding inhibitory factor from human placenta. Partial purification, characterization and biological effects.

A factor which inhibits the binding of 3H-phorbol-12,13-dibutyrate (PDBu) on different types of cells has been partially purified from human placenta. This factor, phorbol ester binding inhibitory factor (PEBIF), is sensitive to pepsin, but resistant to trypsin, heat and acid (pH 3) treatments and can be precipitated by 80% ethanol with no loss of activity. Inhibition occurs both at 37 degrees C and 4 degrees C and is rapid and reversible. Inhibition on human epithelial cells (FL), on mouse erythroleukaemia cells (FELC clone 19-10) and on rat liver cells (IAR clone 6-1 and clone 20) is non-competitive, whereas on IAR clone 6 and clone 6-7 it is competitive. Differentiation of FELC induced by hexamethylene bisacetamide (HMBA) can be inhibited by 12-O-tetradecanoyl phorbol-13-acetate (TPA) only if TPA-sensitive cells are used, and no inhibition was observed with TPA-resistant cells. PEBIF can also inhibit the differentiation induced by HMBA of TPA-sensitive cells and has no effect on the differentiation of TPA-resistant cells. The extent of inhibition of PDBu binding by PEBIF was similar in these two clones. Like TPA, PEBIF can increase 2-deoxyglucose uptake in mouse fibroblasts (BALB/3T3 cells). Thus, TPA and PEBIF share two biological responses; however, PEBIF failed to mimic other TPA effects, such as induction of Epstein-Barr virus from Raji cells, inhibition of intercellular communication and induction of differentiation of human promyelocytic leukaemia cells (HL-60).

Animals↗
PubMed1981

Receptor-specific large-scale purification of cholera toxin on silica beads derivatized with lysoGM1 ganglioside.

1. A receptor-specific affinity chromatographic method for large-scale purification of cholera toxin is described. The receptor ganglioside for cholera toxin, GM1, is hydrolysed to lysoGM1 which is then covalently coupled, via stabilized Schiff's bases, to porous silica beads (Spherosil) onto which a layer of DEAE-dextran has been adsorbed and cross-linked before coupling. Columns of these Spherosil-DEAE-dextran-lysoGM1 beads, in contrast to particles derivatized with lysoGA1, bound the cholera toxin of Vibrio cholerae culture filtrates, after which the toxin could be eluted with the aid of an acid citrate buffer (pH 2.8). 2. The toxin-binding capacity was directly proportional to the amount of lysoGM1 in the column: 2.3 mg/mu mol lysoGM1. The yield of purified toxin after acid elution and pH neutralization was essentially quantitative (83-107%). 3. The affinity-purified toxin contained less than 5% impurities, but consisted of a mixture of predominantly intact holotoxin and B subunit protomer which could readily be separated by gel filtration on Sephadex G-100. 4. Scaling up of the technique was possible: a 1 kg column enabled us to treat 1000-1 cultures of V. cholerae and thus to isolate 20 g of cholera toxin per cycle.

Animals↗
PubMed1980

Separation of gangliosides on a new type of anion-exchange resin.

A new anion exchange resin, Spherosil-DEAE-Dextran, consisting of porous glass beads covered with cross-linked DEAE-Dextran, was used in the separation of gangliosides. The gangliosides were eluted from the resin with a discontinuous gradient of potassium acetate in methanol, separating the gangliosides quantitatively into mono-, di, tri-, tetra- and pentasialoganglioside fractions. The new resin was found to have higher binding capacity, to show less unspecific adsorption and to give a better separation of the higher oligosialogangliosides than did DEA-Spherosil, QAE-Sephadex, DEAE-Sephadex and DEAE-Sepharose. Anion exchange chromatography improved discrimination between closely allied gangliosides as well as quantification and identification of individual gangliosides, especially the minor ones. The new procedure was used in the separation of the gangliosides in human infant forebrain and cerebellum.

Adult↗
PubMed1978

[The passive hemagglutination test in the evaluation of antitetanus immunity].

The conditioned, passive hemagglutination method, which is simple, quick, economical and very sensitive, is suited for large-scale studies in which it is not possible to carry out the in vivo seroneutralization. However, our experience has confirmed that it has certain drawbacks and restrictions: (1) the technique must be applied very carefully and good laboratory training is required. The results obtained by this method vary according to several factors, especially the degree to which the antigen has been purified and its blood carriers, therefore these results are not always consistent; (2) the antibodies found were not a good indication of the degree of protection except at high titers. A study of correlations between HA titers and neutralizing (mice) titers carried out on the basis of 509 double titrations has demonstrated that, whereas they are satisfactory in clearly immune subjects, they show only mediocre results in subjects who are receptive or who are displaying a primary response: a wide range of variation has been observed as well as an optimalization of HA titers, perhaps because of IgM's. Therefore, the HA method, despite its usefulness, cannot provide precise evaluations for: --the amount of protection provided by an anti-tetanus vaccine, --the proportion of protected subjects in a certain group of people, --an injured person's anti-tetanus immunity. We should work to develop in vitro tests which are both sensitive and reliable in terms of the anti-tetanus protection threshold.

Adolescent↗
PubMedDate not supplied

[Experimental cholera in monkeys].

The immune response to Vibrio cholerae was studied in baboons, rhesus monkeys and marmosets inoculated by the oral, intraintestinal or intravenous route with various strains of V. cholerae. Sera were collected from all animals on days 2, 6, 10, 17, 24, 32, 45 and 60 after infection. Serum protein, immunoglobulins (IgA, IgG, IgM), GOT, and alkaline phosphatases were determined. The results showed that baboons and rhesus monkeys were not susceptible to cholera infection under these experimental conditions. However, we were able to induce a lethal cholera infection in cotton-topped marmosets. In baboons and rhesus monkeys serum IgG levels decreased significantly following inoculation with V. cholerae; however, the ratio of GOT, alkaline phosphatase and antibodies against toxin were only slightly modified.

Alkaline Phosphatase↗
PubMedDate not supplied

[Human collagen IV lenses and epikeratoplasy in monkeys. Study of epithelial cicatrization].

A previous study showed the good tolerance of the human type IV collagen lenses implanted by epikeratoplasty in 8 monkeys. It also showed type IV collagen is a good material for the reepithelialization. But we have been interested in the stability of the epithelial healing. The ultrastructural study found anchoring structures. However these were inconstant. So the authors try to understand better the mechanisms of this synthesis of the anchoring structures and describe the future ways of this experimental study.

Animals↗
PubMedDate not supplied

[Viscous human collagen IV. Physical properties and experimental tolerance].

Viscous solutions of collagen IV have been used experimentally on rabbits and monkeys. The physical properties of the solution allow a first class visco-surgery. Tolerance is studied: degradation and absorption in the anterior chamber, intraocular pressure, endothelial effects, biological sensitivity. Good tolerance and mechanical properties are said excellent and use during human surgery has started.

Animals↗