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Biomedical subjects

J Lecomte

Publications and source records attributed to J Lecomte.

At least 109 records · Page 6Linked to original sources
PubMed1985

Pro-inflammatory flavonoids which are inhibitors of prostaglandin biosynthesis.

Catechin dimers induce a large long-lasting oedema when injected in the paw of the rat. This oedema is not inhibited by methysergide, promethazine, indomethacin, phenidone, bromophenacyl bromide and colchicine. It is not modified in rats made leukopenic by methotrexate. It is slightly delayed in Brown Norway rats which were kallikrein-kininogen deficient. Similarly catechin dimers induce the formation of a large peritoneal exudate in the rat. The exudate contains insignificant levels of leucocytes and 5-hydroxytryptamine. It contains kinins but its PG content is very low. The exudate does not activate (14C)-arachidonic acid into PG. Catechin dimers induce kinin formation in rat plasma "in vitro". They inhibit the formation of PG and HETE-like compounds from (14C)-arachidonic acid by rat peritoneal cells "in vitro". Catechin dimers administered at sub-irritant doses reduced carrageenan-induced oedema. Catechin dimers at low doses have an anti-inflammatory effect which may depend on PG synthesis inhibition. At larger doses, they induce inflammatory responses which occur with almost complete lack of participation of PG.

Animals↗
PubMed1985

Hybridoma antibodies produced against bromelain derived cores of influenza virus.

Splenic lymphocytes from BALB/c mice immunized with "cores" of influenza virus, obtained after bromelain cleavage of the surface glycoprotein, were fused with the P3-NS1/1-Ag-1 mouse cell line to yield hybridoma cultures. Among 20 stable cloned hybrid cells secreting monoclonal antibodies, one was specific for the nucleoprotein (NP), 11 were specific for the membrane (M) protein and eight were specific for the hemagglutinin (HA). These "cores" used as immunogen contained only the internal proteins of the influenza virus, namely the three polymerases, the NP and the M protein and no HA when examined by standard procedures of SDS-PAGE, electron microscopy and hemagglutination activity. It thus appeared that a small amount of contaminating antigens can sensitize a sufficient number of mouse B cells to be selected as hybrid partners. These antibodies were provisionally assigned as anti-carbohydrate attached to the HA.

Animals↗
PubMed1984

Proton nuclear magnetic resonance investigation of the heme cavity structure of liver fluke (Dicrocoelium dendriticum) methemoglobin.

The 1H nuclear magnetic resonance characteristics of met-cyano and met-aquo hemoglobin from the sheep bile duct parasite Dicrocoelium dendriticum have been compared to those of other monomeric hemoglobins and myoglobins. By varying temperature and pH, it was found that the studied material is a mixture of several isozymes differing slightly in their structural features around the heme cavity. The heme in-plane rhombic asymmetry, as indicated by the spread of the heme methyl hyperfine shifts, is intermediate between that of sperm whale myoglobin and leghemoglobin. The proximal histidine is present and its dynamic properties, as probed by the exchange of the ring NH with bulk solvent protons, point towards a cavity more stable than those of sperm whale myoglobin and leghemoglobin. In the met-cyano form, an exchangeable proton was detected close to the iron center that was tentatively assigned to an arginine residue located three amino acid residues closer to the C terminus than the proximal histidine. The transition from the met-aquo form to the met-hydroxy form occurring at pH 8.1 and previously detected by optical methods was observed. Furthermore, consideration of the mean heme methyl hyperfine shift average indicates that the iron remains six-co-ordinate down to below pH 4.5 irrespective of an acid-transition (pK approximately 5) in the protein. However, the presence of a "pseudo" six-co-ordinate (i.e. high-spin, in-plane, five-co-ordinate) iron at pH values below the acid-transition pK cannot be excluded on the basis of the presently available data. The pH dependence of several resonances in both the met-cyano and met-aquo forms of the protein reflect a pK value compatible with the titration of a heme propionate.

Animals↗