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Biomedical subjects

L Chedid

Publications and source records attributed to L Chedid.

At least 199 records · Page 11Linked to original sources
PubMed1975

Enhancement of immunity against murine syngeneic tumors by a fraction extracted from non-pathogenic mycobacteria.

The data reported here demonstrate that a preparation extracted from nonpathogenic mycobacteria such as Mycobacterium smegmatis and hereafter referred to as interphase material protected mice against Ehrlich ascitic carcinoma, L-1210 leukemia, and another syngeneic lymphoid leukemia. Furthermore, mice treated by this preparation were much less susceptible to endotoxins than when stimulated by BCG (bacillus Calmette-Guerin) or M. smegmatis cells. Moreover, guinea pigs treated by interphase material administered in Freund's incomplete adjuvant showed an increased immune response, yet their sensitivity to tuberculin was much weaker than that of controls sensitized with Freund's complete adjuvant. Finally, resistance to Columbia SK virus infection could be demonstrated when interphase material was administered to mice prior to virus challenge.

Adjuvants, Immunologic↗
PubMed1975

Isolation of mitogenic and adjuvant active fractions from various species of Nocardiae.

Delipidated lysozyme digests of Nocardia opaca, N. corallina, and N. rubra have been fractionated by Sephadex filtration. The mitogenic and adjuvant activities of the fractions thus obtained have been investigated. All fractions are mitogenic except the last fraction of N.rubra, but the N. opaca products induce a stronger stimulation of mouse spleen lymphocytes than the corresponding fractions of the two other species. The activity of the first Sephadex fractions of each strain has been compared to other mitogens (concanavalin A, lipopolysaccharide). All fractions are adjuvant, although one of them, the last Sephadex fraction of N. rubra, does not contain peptidoglycan; its activity must thus be attributed to another kind of molecule. Fractionation of the first Sephadex fraction of N. opaca by centrifugation in glacial acetic acid led to a separation of adjuvant and mitogenic activities.

Adjuvants, Immunologic↗
PubMed1975

Biological activities of endotoxins detoxified by alkylation.

It has been previously observed that lipopolysaccharides can be detoxified by alkylation and yet retain their adjuvant activity. Our present findings confirm these results and show, moreover, that these derivatives did not lose their capacity to protect mice against lethal irradiation and lost only partially their ability to interrupt pregnancy or to induce blast transformation of murine B-lymphocytes. However, in contrast with lipopolysaccharides, these alkylated preparations did not enhance the nonspecific resistance of mice to a bacterial infection. The various bilogical functions of endotoxins can therefore be separated and are not uniformly related to their toxicity.

Abortion, Spontaneous↗
PubMed1975

Blast transformation of rabbit B-derived lymphocytes by a mitogen extracted from Nocardia.

Nocardia water soluble mitogen (NWSM) is known to stimulate mouse and rabbit lymphoid cells and to act selectively on murine B-derived lymphocytes. In this paper, evidence is presented that NWSM is also a mitogen for rabbit bursal equivalent cells and does not bring about blast transformation of thymus-derived rabbit cells. Pretreatment of rabbit spleen lymphocytes with antibody directed against rabbit thymus lymphocyte antigen (anti RTLA serum) and with complement did not affect the strong increase of thymidine incorporation which follows stimulation with NWSM. The mitogen-induced polyclonal activation of antibody-forming cells and resulted in the presence of 30% of cells with the ultrastructural characteristics of plasmocytes. These observations led to the conclusion that NWSM is a mitogen for a B-derived lymphocyte of the rabbit.

Animals↗
PubMed1975

[Protective effects of bacterial immunostimulants in mice infected by "Klebsiella pneumoniae" resistant to antibiotics after mutation or by plasmid transfer].

A streptomycin-resistant strain of K. pneumoniae obtained after mutation in vitro was found to be less virulent than the sensitive strain in mice. However, a single injection of lipopolysaccharides (LPS) administered 24 hours before challenge increased the host's resistance to both strains. In contrast, the virulence was not changed in K. pneumoniae accepting R-factors for ampicillin, streptomycin, chloramphenicol, tetracycline and sulphonamide. The plasmids were transferred to K. pneumoniae from two strains of Escherichia coli possessing different R-factors with the same resistance pattern. As in the first case, mice pretreated by endotoxin were protected against a challenge by microorganisms carrying R-factors. The capacity of the stimulated host to destory resistant or sensitive organisms was of the same order. Klebsiella recovered 5 or 24 hours after infection from the blood, liver and spleen did not lost their antibiotic-resistance. In this study, BCG and Corynebacterium granulosum were also used. Like LPS, these two immunostimulants protected very effectively mice infected with K. pneumoniae rendered resistant to antibiotics by R-factor transfer.

Ampicillin↗
PubMed1975

Mitogenic effect of bacterial peptidoglycans possessing adjuvant activity.

Two purified peptides extracted from E. coli or B. megaterium strongly stimulated the spleen lymphocytes of rabbits and of normal or nude mice. Both preparations can substitute for Mycobacteria in Freund's complete adjuvant. The peptidoglycan extracted from M. lysodeikticus by a similar procedure which lacks adjuvant activity, did not induce blast transformation. However, the monomere of the E. coli peptidoglycan was devoid of mitogenicity although it has also a marked adjuvant activity.

Adjuvants, Immunologic↗
PubMed1974

Blastic transformtion of mouse spleen lymphocytes by a water-soluble mitogen extracted from Nocardia.

A water-soluble extract of Nocardia markedly increased in vitro [(3)H]thymidine incorporation by mouse spleen lymphocytes. The blastogenic activity of the extract and lipopolysaccharide was studied comparatively on various mouse lymphocyte subpopulations. The data obtained by [(3)H]thymidine incorporation and by electron microscopy have demonstrated that this preparation stimulates selectively mouse bone-marrow-derived cortisone-sensitive lymphocytes. This stimulation is related neither to a natural infection of mice with Nocardia organisms nor to the presence in Nocardia water-soluble mitogen of a lipopolysaccharide contaminant or of a lipopolysaccharide-like material.

Animals↗
PubMed1973

Preparation and biological properties of water-soluble adjuvant fractions from delipidated cells of Mycobacterium smegmatis and Nocardia opaca.

Digestion by lysozyme of delipidated cells of Mycobacterium smegmatis liberates a water-soluble immunoadjuvant fraction which is chemically very similar to the water-soluble adjuvant (WSA) obtained previously from purified cell walls, but which contains somewhat more non-peptidoglycan amino acids. The yield of peptidoglycan-arabinogalactan complex is about 10 times greater starting from whole cells than from cell walls. The main biological properties of this "neo-WSA" are described: it increases circulating antibodies to ovalbumin in guinea pigs, it does not produce polyarthritis in rats or induce hypersensitivity to tuberculin, it does not increase susceptibility to histamine or hyperreactivity to endotoxin, and does not produce spleen and liver hypertrophy. Analogous immunostimulant fractions have also been obtained from delipidated cells of Nocardia opaca by lysozyme treatment.

Adjuvants, Immunologic↗
PubMed1972

Biological study of a nontoxic, water-soluble immunoadjuvant from mycobacterial cell walls.

Whole mycobacterial cells, which are used in Freund's complete adjuvant, besides inducing hypersensitivity to tuberculoprotein, also can elicit hyperreactivity to endotoxins, lymphoid hyperplasia, and allergic polyarthritis in rats. The data reported here demonstrate that a potent water-soluble adjuvant obtained from mycobacterial cell walls is also effective in increasing the immune response to viruses, and that it is free of the toxic effects observed with whole mycobacterial cells.

Adjuvants, Immunologic↗