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Biomedical subjects

J F Petit

Publications and source records attributed to J F Petit.

At least 73 records · Page 4Linked to original sources
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

Chemical structure of the cell wall of Mycobacterium tuberculosis var. bovis, strain BCG.

BCG cell walls contain approximately 30% free lipids like other mycobacterial cell walls. The insoluble skeleton of the cell wall is made up of two covalently linked polymers, a peptidoglycan and an arabinogalactan mycolate, with which are associated non peptidoglycan amino acids and a glucan. We present data on two structural features: 1. The "non peptidoglycan" amino acids; they form two kinds of compounds: peptide chains which can be solubilized by proteolytic enzymes and a trypsin-chymotrypsin insensitive poly-alpha-L-glutamic acid. 2. Presence of meso-DAP-meso-DAP1) interpeptide linkages in the peptidoglycan: this new type represents at least 50% of the interpeptide linkages of the cell wall of the BCG strain.

Amino Acids↗
PubMed1975

Peptidoglycan adjuvants: minimal structure required for activity.

The chemical structure of the adjuvant active fraction of mycobacterial cell walls has been investigated. It had been shown previously that soluble peptidoglycan fragments obtained from cell walls of Mycobacteria by lysozyme digestion or by other treatments act as adjuvants for increasing both humoral and cellular immunity. We then found that even the monomer subunit of the peptidoglycan of Mycobacteria (i.e. a disaccharide-tetrapeptide) is adjuvant active; then, similar compounds from other strains of bacteria were tested; the monomeric subunits of meso-diaminopimelic acid as well as L-lysine containing peptidoglycans were found to be adjuvant active. The smallest active compound studied so far is N-acetyl-muramyl-L-alanyl-D-isoglutamine synthesized for us by SINAY et al. (1975).

Adjuvants, Immunologic↗
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

Isolation and properties of a macromolecular, water-soluble, immuno-adjuvant fraction from the cell wall of Mycobacterium smegmatis.

Trypsin- and chymotrypsin-treated delipidated cell walls of Mycobacterium smegmatis were digested overnight with lysozyme. The water-soluble products thus obtained were filtered on a column of Sephadex G-50; the first peak, excluded from the column, has immunological adjuvant activity. The material of the excluded peak is obtained after lyophilization as a snow-white, fluffy material, soluble in water and insoluble in organic solvents. It behaves as a slightly polydisperse macromolecule in an ultracentrifuge, with an approximate molecular weight of 20,000. All the constituents of this material are typical bacterial cell-wall constituents; thus, the water-soluble adjuvant is considered to be an "oligomer" of the cell wall. When added to Freund's incomplete adjuvant with an antigen (e.g., ovalbumin) and injected into hind-foot pads of guinea pigs, this water-soluble adjuvant increases the amount of precipitating antibodies and induces hypersensitivity to ovalbumin and the biosynthesis of gamma(2)-type precipitating antibodies. The water-soluble material has a stronger adjuvant activity than equal amounts of whole bacteria, cell walls, or wax D, and seems to be the first well-defined, water-soluble, adjuvant-active fraction isolated from Mycobacteria.

Adjuvants, Immunologic↗