[Antibiotics and chemotaxis in agarose. The role of incubation conditions and application to several fluoroquinolones]. / Antibiotiques et chimiotactisme en agarose. Rôle des conditions d'incubation et application à plusieurs fluoroquinolones.

Nelson's agarose technique for the in vitro measurement of leukocyte chemotaxis proved to be well suited in the context of pharmaco-toxicological testings, despite several discrepancies in the literature, probably due to varied incubation conditions. Thus, doxycycline (25 micrograms/ml) when added to both the leukocyte suspension and the agarose was shown to exert a significantly more pronounced depressant effect. Using these conditions of improved sensitivity, three fluoroquinolones, i.e. norfloxacin, ofloxacin and pefloxacin (2, 10 or 25 micrograms/ml) failed to depress chemotaxis markedly.

[Chemotactic response of human polynuclear neutrophils after in vivo administration of spiramycin]. / Réponse chimiotactique des polynucléaires neutrophiles humains après administration in vivo de spiramycine.

The chemotactic response of polymorphonuclear leukocytes using the agarose method, has been studied in six healthy volunteers, immediately prior and after a 5-day oral administration of spiramycin, 6 million units per day. The influence of spiramycin proved to be small as the directed and spontaneous migration were decreased by 21% and 18% respectively. Despite the fact that spiramycin can penetrate into leukocytes, these results indicate that no clinically relevant alterations of chemotaxis are likely under therapeutic conditions.

Effects of josamycin on polymorphonuclear leucocyte chemotaxis.

The effects of josamycin on the chemotactic response of blood polymorphonuclear leucocytes were studied. After oral administration of 2 g/day or 50 mg/kg/day for five days in man and rats respectively, polymorphonuclear chemotaxis was reduced by 20%. After in-vitro incubation with 10 mg/l josamycin chemotaxis was unaltered, whereas a 15% decrease was noted with 25 mg/l josamycin. These data suggest that josamycin is unlikely to severely impair chemotaxis in patients.

Effects of erythromycin, josamycin and spiramycin on rat polymorphonuclear leukocyte chemotaxis.

The effects of three macrolide antibiotics were studied on rat polymorphonuclear leukocyte chemotaxis. Rats were given 25 mg/kg twice a day of either erythromycin, josamycin or spiramycin by gastric intubation for 5 days. In all cases, chemotaxis was found to be impaired by 10-20% only. As macrolides are known to reach high intracellular concentrations within polymorphonuclear leukocytes, our results suggest that these antibiotics are unlikely to exert a deleterious influence on the chemotactic response of treated patients.

[Electrophoretic study of aged butyrylcholinesterase after inhibition by soman]. / Etude électrophorétique de la butyrylcholinestérase agée après inhibition par le soman.

The following states of purified tetrameric form (C4) of human plasma butyrylcholinesterase were studied by electrophoretic techniques: native, inhibited by soman and by methane sulfonyl fluoride and soman-aged. In order to detect a significant conformational change of the aged cholinesterase as compared to the non-inhibited (native) species, enzymes were treated with a set of bifunctional reagents (diimidates) of different chain lengths. After denaturation, the cross-link products were subjected to sodium dodecyl-sulfate polyacrylamide gel electrophoresis. The peak areas of the cross-linked species and the parameters of cross-linkability were calculated from densitometric data, versus the maximal effective reagent length. The effect of occupancy of the esteratic site by substituted phosphonyl group and by methyl-sulfonyl residue on the binding activity of the anionic site was studied by affinity electrophoresis at varying temperatures with immobilized-procaïnamide as ligand. Apparent dissociation-constants of the enzyme-ligand complexes were estimated from measurement of mobilities versus ligand concentration. Corresponding thermodynamic quantities were calculated from Van't Hoff plots and basic thermodynamic equations. The reactivity of aged-cholinesterase with diimidates was similar to that of the native enzyme. Affinity for immobilized-procaïnamide was slightly lowered in aged and inhibited enzymes as compared to the native and sulfonylated enzymes. As for the ligand-induced isomerization of anionic site (A----B), revealed by affinity electrophoresis, the ligand concentration at the midpoint of transition (A = 0,5) was slightly greater for the aged enzyme than for the native one. From these results, the following conclusions can be drawn: the dealkylation of soman-cholinesterase conjugate (aging) does not seem to induce structural changes detectable in the cross-linkability of lysyle residues at the subunit interfaces and on the surface of the tetrameric enzyme. On the other hand, the affinity of the anionic site and ligand-induced isomerization process are altered in soman-inhibited and aged enzymes. These data suggest the occurrence of a weak conformational change of the active center and/or the formation of non-covalent bonds between the methylphosphonyl residue and side chain groups as a result of the dealkylation reaction.