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G Lejeune

Publications and source records attributed to G Lejeune.

At least 19 recordsLinked to original sources
PubMed2000

Alkyl-polyacrylate esters are strong mucosal adjuvants.

Synthetic polymers were examined for their potency to enhance mucosal immune responses to inactivated antigens. Aqueous solutions of polyacrylic acid with a MW of 450 kDa (p[AA]) or an butyl-ester thereof with 16% esterification (Butyl16-p[AA]) plus antigen were administered twice intranasally in mice with a 2 week interval. The frequency of IgA-antibody secreting cells (ASCs) in lung cell suspensions was determined 1 week after the second immunisation. Both polymers significantly enhanced the IgA response against inactivated Newcastle disease virus (iNDV), inactivated influenza virus strain MRC-11 (iMRC-11), haemagglutinin/neuraminidase subunits of influenza virus strain A/Texas (HA/NA) and bovine serum albumin (BSA). Butyl16-p(AA) was significantly more effective than non-derivatised p(AA), cholera toxin B subunit (CTB) or liposomes. The factor of increase in IgA-ASCs varied from <10- to >100-fold and depended on the type of antigen, the dose of antigen and the adjuvant. Extremely high responses of about 10,000 IgA-ASCs per million lung cells were detected after immunisation with 5 microg HA/NA plus 50 microg Butyl16-p(AA). Intranasal immunisation with Butyl16-p(AA) resulted in high IgA responses, not only in the lungs, but also in the spleen and in high IgG responses in these organs. We concluded that alkyl-esters of polyacrylate are an interesting, novel category of mucosal adjuvants.

Acrylic Resins↗
PubMed1999

Sulfolipo-cyclodextrin in squalane-in-water as a novel and safe vaccine adjuvant.

Previously, we described synergistic adjuvanticity of combinations of synthetic sulfolipo(SL)-derivatives of polysaccharide (SL-polysaccharides) and squalane-in-water emulsions (squalane/W). In this paper, effects of type of polysaccharide and nature of oil on adjuvanticity, reactogenicity and stability are described. SL-derivatives of the following polysaccharides were synthesised: synthetic polysucroses with weight-average molecular weight (MW) of 400,000 (Ficoll400), 70,000 (Ficoll70) and 39,000 Da (Ficoll39), polyfructose of 5,000 Da (inulin), linear polyglucose of 1,200 Da (maltodextrin) and cyclic polyglucose of 1,135 Da (beta-cyclodextrin). The number of sulphate groups per monosaccharide of the different SL-polysaccharides varied between 0.15 and 0.23 and the number of lipid groups per monosaccharide between 1.15 and 1.29. Adjuvant formulations were prepared by incorporating these SL-polysaccharides into oil-in-water emulsions of either squalane, hexadecane, soya oil or mineral oil. Adjuvanticity of the formulations obtained for humoral responses to inactivated pseudorabies virus (PRV) and inactivated influenza virus strains A/Swine (A/Swine) and MRC-11 (MRC-11) in pigs and MRC-11 and ovalbumin (OVA) in mice depended on the type of oil (squalane = mineral oil > hexadecane = soya oil) but not on the type of polysaccharide backbone of the SL-derivative. Reactogenicity assessed by local swelling in mice decreased with decreasing MW (SL-Ficoll400 = Ficoll70 = Ficoll39 > SL-inulin = SL-maltodextrin > SL-cyclodextrin) when combined with squalane and decreased with the type of oil in the following order: squalane > mineral oil > hexadecane > soya oil when combined with SL-Ficoll400. Stability of the SL-polysaccharide/squalane/W emulsions at elevated temperature increased with decreasing MW of the SL-polysaccharide (SL-Ficoll400 < SL-Ficoll70 = SL-Ficoll39 < SL-inulin = SL-maltodextrin = SL-cyclodextrin). SL-cyclodextrin/squalane/W remained stable for > 2.5 years at 4 degrees C, > 18 weeks at 37 degrees C and > 10 days at 60 degrees C. We concluded that reactogenicity and stability but not adjuvanticity of SL-polysaccharide/squalane/W formulations depended on the MW of SL-polysaccharide and that SL-cyclodextrin/squalane/W is a promising non-mineral oil adjuvant as it combines strong adjuvanticity (i.e. better than the mineral oil-based adjuvant presently applied) with low reactogenicity and good stability.

Adjuvants, Immunologic↗
PubMed1998

Effect of various adjuvants on secondary immune response in chickens.

Stimulatory effects of several types of adjuvants on secondary antibody response to inactivated Newcastle disease virus (iNDV) were examined in chickens. For this purpose, animals were primed with iNDV without adjuvant resulting in a low but significant antibody response, boosted with iNDV plus adjuvant 3 weeks later, and analysed for specific antibody titres in serum 3 weeks after the booster. Water-in-mineral oil emulsion (W/O) caused significant increase in antibody titres measured in an indirect enzyme-linked immunosorbent (ELISA), haemagglutination inhibition (HI), and virus neutralisation (VN) assay. The adjuvants tested included three oil-in-water emulsions (i.e. mineral oil-in-water, sulpholipo(SL)-Ficoll400/squalane-in-water and sulpholipo-cyclodextrin/squalane-in-water), three negatively-charged polymers with high molecular weight (i.e. polyacrylate, polystyrenesulphonate and sulpho(S)-Ficoll400) and two surface-active agents (i.e. dimethyldioctadecylammonium bromide (DDA) and Quil A). These adjuvants enhanced significantly the secondary immune response but none reached the titre obtained with W/O. Combinations of adjuvants with distinct physicochemical properties, i.e. polyacrylate and DDA revealed only slight, beneficial effects. We concluded that the various types of adjuvants tested can stimulate secondary immune responses in primed animals but that W/O is superior.

Adjuvants, Immunologic↗
PubMed1998

Analysis of oral uptake of a synthetic adjuvant by an immunoassay with monoclonal antibodies.

A blocking ELISA with specific antibodies against a synthetic sulpholipo-polysucrose (SL-Ficoll400) was developed to quantify this vaccine adjuvant component in faeces with the purpose of estimating the uptake thereof by the gastrointestinal tract after oral administration. Specific monoclonal antibodies (MABs) prepared against SL-Ficoll400 did not cross-react with components in murine faeces. SL-Ficoll400 inhibited the reactivity of the MABs in a dose-dependent fashion in the blocking ELISA and the concentration causing 50% inhibition (IC50) was about 1 microg SL-Ficoll400 per milliliter. Derivatives of Ficoll400 lacking sulphate or lipid groups or both were unable to block the MABs (IC50 > 1000 microg/ml) which confirmed the specificity of the test system. Quantification of SL-Ficoll400 in extracts of faeces of untreated mice spiked with SL-Ficoll400 revealed that more than 90% could be recovered. The blocking ELISA was used to quantify SL-Ficoll400 in the faeces of mice given this compound orally. One, two and three days after oral administration, the cumulative recovery of SL-Ficoll400 in faeces was 30, 40 and 92%, respectively. From these data, we concluded that the MABs obtained were specific for SL-Ficoll400, that SL-Ficoll400 in murine faeces could be quantified by a blocking ELISA with MABs and that SL-Ficoll400 was poorly absorbed by the gastrointestinal tract.

Adjuvants, Immunologic↗
PubMed1998

Quantitative analysis of a synthetic adjuvant by an immunoassay.

Antibodies against a sulpholipo-derivative of synthetic polysucrose (SL-Ficoll) were prepared with the purpose of developing a detection system for this adjuvant component. SL-Ficolls with polysucrose backbones of 400 kDa (SL-Ficoll400) or 22 kDa (SL-Ficoll22) were not immunogenic. However, SL-Ficoll22 conjugated to bovine serum albumin (SL-Ficoll22-BSA) induced high levels of specific antibodies against SL-Ficoll in mice as determined by an indirect ELISA with either SL-Ficoll400 or SL-Ficoll22 as coating antigen. The specificity of the antibodies was analysed further in a blocking ELISA with SL-Ficoll400 as coat. Dose-dependent inhibition of the ELISA titre was obtained with SL-Ficoll22 and SL-Ficoll400 and the concentration causing 50% inhibition (IC50) was < 1 microg/ml. Non-derivatised polysucrose (Ficoll400) and compounds lacking either lipid or sulphate were not recognised (IC50 > 1000 microg/ml). The reaction of SL-Ficoll400-derivatives with antibodies increased with increasing sulphate and lipid content and maximal inhibition was produced by compounds with a composition similar to the SL-Ficoll22 used for immunisation. Quantitative analysis of SL-Ficoll400 in adjuvant formulations comprising SL-Ficoll400 incorporated in a squalane-in-water emulsion revealed high recovery and sufficient precision. From these data, we conclude that specific antibodies are generated against the synthetic SL-Ficoll400 and that this component of a novel adjuvant formulation can be quantified by an immunoassay.

Adjuvants, Immunologic↗
PubMed1998

Alkyl-esters of polyacrylic acid as vaccine adjuvants.

Previously, we demonstrated that polyacrylic acid (PAA) augmented significantly the immune response to inactivated Newcastle disease virus (iNDV) in chickens, but that efficacy was insufficient to replace the water-in-mineral oil (W/O) adjuvant applied for boosting primed animals. Attempting to improve its adjuvanticity, PAA with weight-average molecular weight (Mw) of 450 kDa was grafted with alkyl-chains by esterifying the carboxylic groups with octanol and butanol. The butyl-PAA and octyl-PAA esters obtained varied in degree of esterification between 10% and 92%. Adjuvant activity of water-soluble esters for humoral responses to iNDV was examined in chickens primed previously with iNDV without adjuvant. The alkyl-PAA esters exhibited significantly higher responses than unmodified PAA and titres increased with increasing dose of adjuvant. At doses of 2 mg per animal, octyl- and butyl-PAA esters with a substitution rate of 16% (octyl16-PAA and butyl16-PAA, respectively) gave similar titres as W/O. In aged animals primed with live NDV at early age, butyl16-PAA and W/O elicited comparable antibody responses. Butyl16-PAA was also more effective than PAA in stimulating primary immune responses in mice which was accompanied by stronger local reaction determined by monitoring swelling at the site of injection. Reactogenicity of butyl16-PAA was less than of W/O. We concluded that alkyl-PAA esters are strong adjuvants for primary and secondary responses and that they are promising alternatives to the mineral oil-based adjuvants presently used in various veterinary vaccines.

Acrylic Resins↗
PubMed1997

Sciatic nerve regeneration through venous or nervous grafts in the rat.

This study analyses the interest of isologous venous grafts filled with saline or with Schwann cells versus nerve grafts as guides for regeneration of the sciatic nerve in 35 Wistar rats. Electrophysiological parameters (conduction velocities and distal latencies of motor responses) and the functional index of De Medinacelli were measured several times from 1 month to 1 year after surgery. An histological analysis was performed on 2 control rats and on 3 rats killed 6 or 12 months after surgery: the total number of fibers was counted on a montage photoprint of the whole nerve, and the diameters of axons and the thickness of the myelin sheath were measured on digitized images. With a portion of nerve as guide, the regeneration is faster than with a vein. However, regeneration after 6 months is at least as good with a venous graft filled with Schwann cells, as assessed by electrophysiological, functional, and histological analysis. The addition of Schwann cells in grafted veins allows the nerve to regenerate through longer gaps than previously described (25 vs 15 mm). In order to assess the quality of nerve regeneration, functional, electrophysiological, and histological analysis are complementary.

Animals↗
PubMed1991

Non-toxic antiseptic irrigation with chlorhexidine in experimental revascularization in the rat.

The effect of different wound irrigation fluids upon femoral arteries and veins was investigated in the rat, using microsurgical techniques. Toxicity was evaluated by microscopical observation after selective staining of histological slides. Povidone-iodine, 10%, proved to be a very irritant solution, provoking an attack on the vascular endothelium and secondary thrombosis. Chlorhexidine at 0.05%, 0.02% and 0.001% was found by contrast to have a very low toxicity which was comparable to physiological saline. Experimental investigation of antiseptic solutions should not only include the determination of the antibacterial effect, but also the potential for cell toxicity, using an irrigation technique.

Animals↗
PubMed1989

[Current trends in experimental peripheral nerve regeneration].

Large posttraumatic defects in the peripheral nervous system need to discover methods to solve the demand of nerve grafts. There is no definite answer now. The authors present a model for nervous regeneration studies. Experiments are performed in the Wistar rat. A venous isograft is used to bridge defects of various size in a divided rat sciatic nerve. The venous tube is a guide for axonal regeneration. In one series, the tube is filled with physiological saline and, in a second one, neonatal Schwann cells are injected in the venous isograft. Results recorded are a combination of quantitative methods: neurophysiology and morphometry. The injection of neonatal Schwann cells is able to stimulate nerve regeneration but not completely.

Animals↗
PubMed1988

[Preliminary study on nerve regeneration through an autologous venous tube].

Large posttraumatic defects in the peripheral nervous system bring up serious problems to the surgeon. There is no definitive answer yet. The authors present a model for nervous regeneration studies; venous autograft was used to bridge defects in a divided rat sciatic nerve; the venous tube guided the regenerating axons towards the distal stump over up to 1.9 cm length. Preliminary studies about nervous regeneration stimulation with autologous Schwann cells are discussed.

Animals↗
PubMed1988

[Radiation-induced thyroid cancer].

We describe thyroid carcinomas observed in two male patients after cervical irradiation in infancy. In the first case, irradiation was given for cervical angioma and in the second case, for enlarged thymus. A long time interval (16 and 43 years) elapsed between irradiation and the detection of the epitheliomas. The anatomopathological diagnosis was, for the first patient, papillo-vesicular epithelioma and for the second one, anaplastic carcinoma.

Adult↗