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In order to clarify the possible interactions between nitric oxide (NO) and arachidonic acid (AA) pathways, human amnion-like WISH cells were perifused to measure the effects of the following substances on [3H]arachidonic acid release: (1) sodium nitroprusside (SNP), a nitric oxide donor; (2) 1,1,1-trifluoromethyl-6,9,12,15-heicosatetraen-2-one, a cytosolic phospholipase A2(cPLA2) inhibitor; (3)l-arginine, the substrate of nitric oxide synthase (NOS); (4) 3-(5′-Hydroxymethyl-2′-furyl)-1-benzylindazole and 1H-[1,2,4]oxadiazolo[4,3-α]quinoxalin-1-one, activator and inhibitor of soluble guanylyl cyclase, respectively; (5) a membrane-permeable non-hydrolyzable analogue of guanosine-3′,5′-cyclic monophosphate (cGMP). Furthermore, the effect of SNP on prostaglandin E2(PGE2) release was tested. Exogenous and endogenous NO, as well as the guanylyl cyclase activator and cGMP analogue, significantly increased [3H]arachidonic acid release. Both soluble guanylyl cyclase and PLA2inhibitors counteracted SNP response. Exogenous NO increased PGE2release, although to a much lesser degree compared with arachidonic acid release.

AbstractThis paper describes the production and characterization of biodegradable microparticles containing tetracycline, designed for periodontal disease therapy. The influence of production parameters on microparticle characteristics and antibiotic release modality was studied. Microparticles were made by using different preparation procedures and different polyesters, namely poly(L-lactide), [L-PLA] poly(DL-lactide), [DL-PLA] and poly(DL-lactide-co-glycolide) 50:50, [DL-PLG]. A double emulsion preparation method together with a concentrated salt solution as external phase gave the best results in terms of tetracycline incorporation efficacy. In vitrorelease experiments demonstrated that tetracycline is slowly and appropriately released from microparticles. Release kinetics were found to be influenced by the type of polymer utilized for microparticle production. In vitroexperiments, simulating in vivoconditions were carried out for up to 30 days. Only DL-PLG microparticles showed significant changes in their morphology, whereas L-PLA and DL-PLA were found almost intact after the same period of time.