In vivo cocaine administration influences lymphokine production and humoral immune response.

The effect of in vivo cocaine administration on in vitro mitogen-induced lymphokine production was examined. Splenocyte cultures from BALB/c mice treated with an acute (1 mg/kg) or daily cocaine administration (1 mg/kg/day for 7 consecutive days) were less responsive to induction of IFN-gamma, IL-2 and IL-4 production by mitogen stimuli. We also evaluated the humoral immune response to both a T-dependent (HEL) and a T-independent antigen (rHBcAg). It was found that cocaine inhibits T-dependent antibody production only. This inhibition was greatest when cocaine was given during immunization. The results suggest that T-cell-mediated responses may be more affected by cocaine use/abuse.

The mechanism of action of amtolmetin guacyl, a new gastroprotective nonsteroidal anti-inflammatory drug.

Amtolmetin guacyl (2-methoxyphenyl-1-methyl-5-p-methylbenzoyl-pyrrol-2-acetamido acetate) (MED15) is a new nonsteroidal anti-inflammatory drug (NSAID) with anti-inflammatory, analgesic and antipyretic properties similar to the traditional drugs, but with unexpected gastroprotective effects. In an in vivo rat model, amtolmetin guacyl administered orally demonstrates inhibition of gastric acid secretion following stimulation by various agonists, and up-regulation of gastric bicarbonate production. Pretreatment with MED15 also shows a significant reduction of indomethacin-induced gastric damage in the rat. The reason behind this behaviour appears to be bound to the presence in the MED15 molecule of a vanillic moiety known to stimulate capsaicin receptors. In fact, the antisecretive effect of MED15 is blocked by capsazepine (a specific capsaicin receptor antagonist). This effect is confirmed by the interference found with anti-histamine H(1) drugs. Owing to the connection between capsaicin and calcitonin gene-related peptide (CGRP), a possible effect of MED15 on CGRP receptors was hypothesized, considering the leading role played on gastric mucosa by the predominant sensory neuropeptide of the stomach wall, CGRP. In fact, the anti-secretive and gastroprotective effect of MED15 is abolished by CGRP-(8-37) (the specific CGRP receptor antagonist). The unmodified MED15 molecule is found throughout the gastroenteric tract for long periods of time following oral administration, as further confirmation of the mechanism of action being based on the presence of the vanillic moiety at receptor level.

Effect of a new de-N-acetyl-lysoglycosphingolipid on some tumour models.

A new de-N-acetylated glycosphingolipid termed WILD20, a breakdown product of GM1 obtained through alkaline hydrolysis, and characterized by nuclear magnetic resonance, mass spectrometry and elementary analysis, was found to inhibit phospholipase A2 via phosphokinase C translocation blockade. The substance inhibited various tumour cell lines in vitro, in synergy with doxorubicin and cisplatin. In vivo, it showed an antitumoral effect when both the tumour cells and WILD20 were injected at the same site (peritoneal cavity). Tumour cells, incubated with WILD20, showed a dose-dependent decrease of oncogenicity without impairment of viability. WILD20 also down-regulated tumour cell adherence to laminin and fibronectin. When peritumorally administered, WILD20 impaired tumour growth and potentiated the peritumoral effects of recombinant interleukin 2. The results obtained merit exploration of the therapeutical possibilities of this agent in human cancer patients.

Antiplatelet effects of a new de-N-acetyl-lyso-glycosphingolipid.

Gal beta 1-->3GalN beta 1-->4Gal(3<--2 alpha Neu)beta 1-->4Glc beta-->1Sph (WILD20), a new glycosphingolipid, a breakdown product of the monosialoganglioside GM1 obtained through alkaline hydrolysis, shows dose-dependent platelet anti-aggregating properties in vitro and in vivo. This effect is agonist- and species-independent. The family of lysosphingolipids, to which the compound belongs, is present in platelets particularly after thrombin treatment. WILD20 antiplatelet effect is due to the interference with ADP or thrombin-induced aggregation, probably via phospholipase A2 (PLA2) blockade; the substance is also effective when arachidonic acid is used as an agonist. Serotonin blood levels are also reduced. The substance, orally active at dosages of 0.1-0.01 mg/kg as antiplatelets agent, prolonged bleeding time without interfering with the coagulative or fibrinolytic processes.

Effect of a new de-N-acetyl-lysoglycosphingolipid on chemically-induced inflammatory bowel disease: possible mechanism of action.

A new, orally active de-N-acetylated lysoglycosphingolipid (WILD20) was evaluated as antiinflammatory agent using a model of chemically-induced inflammatory bowel disease (IBD) in the rat to mimic human ulcerative colitis and Chron's disease. IBD was induced by hapten trinitrobenzenesulphonic acid (TNB). WILD20, orally administered as preventive or curative, was demonstrated to be efficacious at daily dosages of 0.1-1 mg/kg for 4-5 days. Damage scores, body weight, spleen weight, colonic tissular levels of LTB4, myeloperoxidase (MPO) and malondialdehyde (MDA) are influenced and brought into parameters of normality. Histological observation demonstrated quicker healing, better repair, reduced inflammation, and poor eosinophil degranulation. The mechanisms underlying WILD20 antiinflammatory effects were investigated: whereas WILD20 fails to show a direct effect on PKC, it reduces PKC translocation to the membrane; cellular PLA2 was consequently greatly reduced through this mechanism and thought to be responsible for WILD20 efficacy towards chemically-induced IBD.

Preparation and characterization of four new variously deacetylated lysogangliosides, breakdown products of GM1.

Four new deacylated lysogangliosides were obtained through alkaline hydrolysis of either C18 or C20 sphingosine homologues of GM1. By this procedure, both the fatty acids residue and the N-acetyl group of sialic acid were removed to give mono-N-acetyl-lysoGM1 (C18 and C20); the additional loss of the N-acetyl group of the acetylgalactosamine moiety gave de-N-acetyl-lysoGM1 (C18 and C20) with three free amino groups. The structures of four deacetylated lysogangliosides were unambiguously characterized by chemical analysis and 1H and 13C NMR spectroscopy as well as by negative ion FABMS. The aim of this study was to isolate pure breakdown products of gangliosides, enabling the evaluation of the mechanism of action of glycosphingolipids through their cleavage and identification of structures of potential pharmacological activity. These new substances were prepared as candidates to influence eicosanoid production and the mechanisms dependent on protein kinase C and phospholipase A2.