Action of tioxamast on various models of anaphylactic shock, hyperreactivity and bronchial inflammation in guinea-pigs.

Tioxamast, an anti-allergic compound inhibiting the release and synthesis of certain mediators of allergy and having no major antagonist effect towards such mediators, was experimented on various models of anaphylactic shock, hyperreactivity and bronchial inflammation in guinea-pigs. Tioxamast does not reduce passive pulmonary anaphylactic shocks induced in anaesthetized or conscious guinea-pigs by i.v. challenge of antigen. Likewise, the compound has no effect on systemic hyperreactivity towards i.v. histamine induced in anaesthetized guinea-pigs after a passive anaphylactic shock caused by i.v. challenge of antigen. On the other hand, tioxamast inhibits passive pulmonary anaphylactic shock induced in guinea-pigs by antigen aerosol in conscious guinea-pigs. Likewise, tioxamast decreases hyperreactivity to inhalation of histamine or carbamylcholine obtained after an active or passive anaphylactic shock by aerosol in conscious guinea-pigs. The oxamate derivative attenuates the increase in number of eosinophils and mononuclear cells obtained in the bronchoalveolar lavage fluid 24 hr after an active anaphylactic shock induced by aerosol. The anti-allergic activity of tioxamast on the various models carried out in guinea-pigs thus appears when these models are induced by a challenge of antigen or mediator by inhalation.

Immunofluorescence study of the action of navelbine, vincristine and vinblastine on mitotic and axonal microtubules.

Among the various non-naturally-occurring Vinca alkaloid compounds, nor-anhydro-vinblastine (Navelbine, NVB) exhibits in preliminary clinical studies broader anti-tumor activity and lower neurotoxicity than vinblastine (VBL) and vincristine (VCR). The action of these 3 Vinca alkaloids on axonal and mitotic microtubules has been studied experimentally in a specific model, the tectal plate anlage of mouse embryos at the earliest stages of neuronal differentiation. Post-implantation embryos were cultured in toto in a medium containing increasing concentrations of drugs. Microtubules were stained using immunofluorescence with a tubulin-specific polyclonal antibody in semi-thin sections after embedding in high-molecular-weight polyethylene glycol. All drugs induced depolymerization of mitotic interpolar microtubules and cell metaphase block at the same concentration. Increasing the concentrations led to progressive depolymerization of kinetochore microtubules. However, NVB was the only drug to induce complete microtubule depolymerization. The activity of the 3 compounds on axonal microtubules was identical: depolymerization of a labile pool of microtubules. This was observed at higher concentrations with NVB than with the 2 other Vinca alkaloids. Our results show that, in this model, NVB is as active on mitotic microtubules as VCR and VBL, and less active on axonal microtubules. None of the 3 drugs modified microtubule length but all appeared to induce disruption of the labile microtubule pool without altering the stable pool.

Biochemical effects of Navelbine on tubulin and associated proteins.

Navelbine (NVB) or 5' nor-anhydro-vinblastine was shown to present a broader antitumor activity and to induce fewer side effects than vinblastine (VBL) or vincristine (VCR). The possible mechanisms of these differences were analyzed with in vitro methods. At substoichiometric concentrations, the three drugs inhibit microtubule assembly. NVB, in comparison with VCR and VBL, is shown to have a lower inhibitory effect. At stoichiometric concentrations, the three drugs are able to induce tubulin aggregation into spirals and paracrystals. This process involves a microtubule-associated protein (MAPs) family referred to as Tau and is inhibited by another MAPs family referred to as MAP2. However, dramatic quantitative and qualitative differences are observed between NVB and VLB or VCR in TAU-induced aggregation of tubulin. The rate and extent of NVB-induced tubulin aggregation is much lower. With NVB, only certain TAU isoforms are able to induce paracrystals, while all TAU isoforms may contribute to VCR-induced or VBL-induced paracrystals. The TAU isoforms that are not able to induce crystallization with NVB, at least in a certain range of concentrations, are probably involved in mitotic microtubules--the hypothetical antitumoral target of vinca alkaloids (VAS). The present work shows for the first time that an anticancer drug is able to discriminate between the various types of microtubules. A next step will be to investigate whether this property is limited to a modulating effect of the various TAU isoforms on the affinity of VAS for tubulin. These biochemical investigations will be extended to tubulins extracted from tumor cell lines in order to further discriminate NVB from the other VAS.

In situ analysis of the action of Navelbine on various types of microtubules using immunofluorescence.

Preliminary clinical studies demonstrated that 5' nor-anhydro-vinblastine, Navelbine (NVB) has a broader antitumor activity and fewer neurotoxic effects than vinblastine or vincristine. The tectal plate anlage of mouse embryos at the earliest stages of neuronal differentiation were used to analyze and compare the effect of NVB, vincristine and vinblastine on axonal and mitotic microtubules after culture of post-implantation embryos in a medium containing the agent. All drugs are active on mitotic microtubules at the same concentration (0.1 mumol/L), inducing a depolymerization of microtubules and a blockade of cells at metaphase. At higher concentrations. NVB is the only one of the three drugs that induces a blockade of the cells at prophase. A depolymerization of axonal microtubules occurs at higher concentrations with NVB than with the two other vinca alkaloids. These results demonstrate that NVB is as active on mitotic microtubules and less active on axonal microtubules than vincristine and vinblastine. These findings can be related to the potent antitumor effect of the drug with minor neurotoxicity.

Comparison of the cutaneous/systemic antiinflammatory activity ratios for desonide and hydrocortisone in various experimental models.

The ratios of antiinflammatory activity after oral administration (oral ED50/cutaneous ED50) for desonide (Locapred) and hydrocortisone (hydrocortisone acetate) were compared in various nonimmunological and immunological experimental models on mouse ears: edema induced by croton oil; primary irritation due to picryl chloride; the acute phase (6 h) and the beginning of the chronic phase (24 h) of inflammation due to cantharidin; delayed contact hypersensitivity to picryl chloride; and the semi-delayed (6 h) and delayed (24 h) phases of contact hypersensitivity to oxazolone. These investigations showed that, besides having a better antiinflammatory effect, desonide had a better ratio of local activity to systemic effect in all the models. In addition, by contrast with orally active doses, locally active doses did not induce any thymolytic effect. Such results were confirmed in rats in which desonide reduced 24 h carrageenin abscess after cutaneous application without any significant thymolytic effect. Hydrocortisone was inactive.

Pharmacological modulation of PAF-acether-induced pleurisy in rats.

Injection of platelet-activating factor (PAF-acether) into the pleural cavity of rats induced the accumulation of a moderately intense exudate within 30 to 60 minutes. By comparison with animals given injections of the vehicle alone, the animals given this mediator had elevated levels of leukotriene C4-immunoreactive material (LTC4 im) in the exudate and decreased quantities of thromboxane B2 (TxB2) and of 6-Keto-F1 alpha-prostaglandin (6-Keto PGF1 alpha). Nifedipine, verapamil, and diltiazem reduced the pleural exudate with no major effect on the mediators. Both salbutamol and theophylline reduced the exudate and the levels of LTC4 im. Acetylsalicylic acid, phenylbutazone and indomethacin significantly inhibited the exudate, greatly lowered the quantities of cyclooxygenase derivatives and tended to increase LTC4 im. Phenidone, which inhibits the cyclooxygenase and lipoxygenase pathways, decreased the exudate and the three mediators. The phospholipase A2 inhibitor, chloroquine, decreased both the amount of exudate and moderately the concentration of LTC4 im. The glucocorticoids studied had no effect on the exudate or on the mediators. These results suggest that the role of the increased LTC4 im in the induction of the pleurisy is not clear.

1-Aryl-2-(aminomethyl)cyclopropanecarboxylic acid derivatives. A new series of potential antidepressants.

A series of 1-aryl-2-(aminomethyl)cyclopropanecarboxylic acid derivatives were synthesized and evaluated as potential antidepressants. Compounds with the Z configuration were synthesized from 1-aryl-2-oxo-3-oxabicyclo[3.1.0]hexane and those with the E configuration from (E)-1-phenyl-2-(hydroxymethyl)cyclopropanecarboxylic acid. The compounds were evaluated in animal tests designed to reveal potential antidepressant activity and the existence of undesirable side effects. Several derivatives were more active than imipramine and desipramine. On the basis of its activity in pharmacological animal tests of antidepressant activity and its potential lack of side effects, 1-phenyl-1-[(diethylamino)carbonyl]-2- (aminomethyl)cyclopropane hydrochloride, midalcipran (INN), was selected for further development. This compound is currently in phase III clinical evaluation.

Cutaneously applied erythromycin base reduces various types of inflammatory reactions in mouse ear.

Erythromycin base was tested by brushing a solution onto the skin in various models of non-immune and immune inflammation produced in mouse ear, namely inflammations induced by croton oil and cantharidin, primary irritation by picryl chloride, and contact hypersensitivity reactions to oxazolone and picryl chloride. On the non-immune inflammations, erythromycin displayed a greater effect than indomethacin, phenylbutazone or acetylsalicylic acid, though less than that of hydrocortisone acetate. It inhibited the hypersensitivity reactions less well. These results suggest some participation of an anti-inflammatory mechanism in the clinical effectiveness of cutaneously applied erythromycin base in some forms of acne.

Psychopharmacology of midalcipran, 1-phenyl-1-diethyl-amino-carbonyl-2-aminomethylcyclopropane hydrochloride (F 2207), a new potential antidepressant.

Midalcipran is a new potential antidepressant selected for its equipotent inhibition of noradrenaline and serotonin uptake and its lack of effect at any postsynaptic receptor. In mice it antagonized the depressant effect of tetrabenazine with an oral ED50 value of 0.5 mg/kg as compared to 2.5 mg/kg for desipramine and 5.1 mg/kg for imipramine. Similar findings were obtained for the inhibition of yohimbine-induced mortality. In the "behavioral despair" test, in mice, immobility was significantly reduced by 10 mg/kg midalcipran whereas 20 mg/kg of desipramine was required for a similar effect. Midalcipran enhanced the behavioral changes induced by 1-tryptophan in the rat and antagonized p-chloramphetamine-induced hyperthermia in mice. In contrast to tricyclic antidepressants, midalcipran showed no anticholinergic, sedative or stimulant properties.

Studies of arylthiazole oxamates in relation to oral antiallergic activity.

25 arylthiazole oxamate derivatives were synthesized and examined for antiallergic activity in the rat passive cutaneous anaphylaxis assay. These compounds were prepared by treatment of the appropriate bromoacetophenone with thioureas to give arylaminothiazoles. Further condensation with alkyloxalyl chloride gave the arylthiazolyl oxamates. Several derivatives showed a 70% inhibition at 5 mg/kg p.o. p-Alkoxy substitution on the phenyl ring resulted in enhanced activity while N-alkyl substitution on the nitrogen amide function inhibited the activity. Ethyl-N-(4-p-methoxyphenyl)-2-thiazolyl oxamate (tioxamast, F-1865) was selected for clinical studies.

Exudative, cellular and humoral reactions to platelet-activating factor (PAF-acether) in the pleural cavity of rats.

The reactions to platelet-activating factor (PAF-acether) injected into the pleural cavity of rats were compared with the reactions in animals injected with 0.9% NaCl. PAF-acether induced a maximum exudate after 30-60 min, which then decreased and disappeared after 24 h. The number of pleural leukocytes in the exudate was clearly decreased 30 min after the injection, was slightly increased after 6 h and was unchanged at other times. The estimation of lipid mediators in the pleural exudate obtained 30 and 60 min after the injection of PAF-acether revealed an increase in type-C4 leukotriene (LTC4) and a decrease in thromboxane B2 (TxB2) and in 6-keto prostaglandin F1 alpha (6-keto PGF1 alpha). In addition, the amount of histamine was found to be lower after 30 min. These results confirm in vivo that some biological effects of PAF-acether seem to involve the participation of other mediators.

Indirect dopaminergic effects of tofisopam, a 2,3-benzodiazepine, and their inhibition by lithium.

Tofisopam, a 2,3-benzodiazepine, has been shown to have anxiolytic activity. However, in contrast to the widely used 1,4-benzodiazepines, it has no anticonvulsant, sedative or muscle relaxant effects. Tofisopam enhanced the behavioural actions of various dopaminergic drugs, both direct agonists, such as apomorphine (climbing behaviour in mice), and indirect agonists, such as (+)-amphetamine and amineptine (jumping behaviour in mice). Chronic treatment with lithium abolished the tofisopam-induced increase in the activity of these dopaminergic drugs. Thus tofisopam appears to induce acutely an increase in the sensitivity of central dopaminergic receptors which can be prevented by pretreatment with lithium.

Biochemical profile of midalcipran (F 2207), 1-phenyl-1-diethyl-aminocarbonyl-2-aminomethyl-cyclopropane (Z) hydrochloride, a potential fourth generation antidepressant drug.

The present study of midalcipran (F 2207), 1-phenyl-1-diethyl-aminocarbonyl-2-aminomethyl-cyclopropane(Z) hydrochloride, was undertaken to determine its biochemical profile. The properties of midalcipran, in inhibiting the uptake of monoamines were tested and compared with that of imipramine. In vitro, midalcipran was found to inhibit the uptake of radiolabelled serotonin and noradrenaline (IC50 = 203 and 100 nM, respectively), but not that of dopamine, into brain slices. Hyperthermia induced by the centrally-acting displacers of monoamines, H77/77 and H75/12, were almost equipotently antagonized by midalcipran, confirming the inhibition of the uptake of serotonin and noradrenaline by midalcipran in vivo (ID50 = 11 and 4.8 mg/kg, respectively). Midalcipran showed no inhibition of the activity of monoamine oxidase in vitro or in vivo. The interaction between midalcipran and neurotransmitter receptors and binding sites in the CNS was studied in the rat in comparison with imipramine and desipramine. In contrast to these two antidepressant drugs, midalcipran showed no affinity for alpha- or beta-adrenoceptors, muscarinic, histaminergic H1, dopaminergic D2 or serotonergic 5-HT2 receptors, suggesting a general absence of anticholinergic, sedative and other side-effects. Midalcipran was equipotent with imipramine at inhibiting the binding of [3H]imipramine. Chronic administration of midalcipran to rats did not alter the number of beta-adrenergic receptors in the cortex, in contrast to imipramine and desipramine which decreased the binding of beta-adrenoceptors. Thus midalcipran appears to act exclusively presynaptically, inhibiting the uptake of serotonin and noradrenaline. This activity, coupled to the total absence of interaction at postsynaptic sites, suggests that midalcipran may be a useful and novel antidepressant drug.