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Biomedical subjects

R Roncucci

Publications and source records attributed to R Roncucci.

At least 37 records · Page 2Linked to original sources
PubMed1985

Levels of ventricular myosin fragments in human sera after myocardial infarction, determined with monoclonal antibodies to myosin heavy chains.

Serum levels of ventricular myosin heavy chains were quantitated in patients with acute myocardial infarction using a competitive radioimmunoassay involving monoclonal antibodies to the b-type myosin heavy chains of a human ventricle. Among the seven antibodies selected for their higher affinity for ventricular myosin heavy chains, only four antibodies detected significant and variable myosin amounts in the serum samples of nineteen patients with acute myocardial infarction; the same antibodies occasionally detected, if at all, low myosin amounts in the sera of patients with no clinical sign of myocardial infarction, and no myosin in the serum of the healthy control subjects. The peak levels of myosin release were observed 4.6 +/- 0.5 days (n = 13, P less than 0.01) after myocardial infarction and correlated rather well with the measured creatine kinase peak levels (the correlation coefficients were between 0.75 and 0.81, P less than 0.01, depending on the monoclonal antibody used for myosin determination). The time courses of myosin release varied according to the complexity of the heart attack observed. It was concluded that the titration of serum myosin was probably of little clinical value for therapeutic intervention during the acute phase of myocardial infarction; it could, however be an effective tool for retroactive detection of an infarct and for late estimation of infarct size.

Adult↗
PubMed1985

Direct immunometric assay of active renin in human plasma.

None of the methods currently available can detect the small numbers of active renin (AR) molecules present in plasma. Among seven monoclonal antibodies (Ab), two Abs were selected which did not recognize the same epitope and could be used in a sandwich assay. The first monoclonal Ab, 3E8, binds soluble renin (B 50% = 1 x 10(-10) mol/l) and does not inhibit its enzymatic activity. It was coupled to magnetic beads (Magnogel) and was used to trap both active and inactive renin from 250 microliters plasma. The second Ab, 4G1, binds renin (B 50% = 3.5 x 10(-10) mol/l), inhibits its enzymatic activity, and recognizes inactive renin less than AR. It was iodinated and used to detect AR trapped on Magnogel by the first Ab during a 4-h incubation. The assay can detect 16 pg/ml in human plasma and is highly reproducible. The AR level of 15 normotensive subjects, aged 20-45 years, in an upright posture and on a normal sodium intake, was found to be 41 +/- 18 pg/ml (MRC renin standard). The plasmas were trypsin-activated and their total renin levels were measured with the same pair of monoclonal Abs. The mean value of 286 +/- 142 pg/ml is similar to the value obtained by other assay systems which measure total renin with Abs recognizing both active and inactive renin. The direct measurement of AR provides a convenient and standardized method, since the production of the two monoclonal Abs is unlimited.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Ethyl loflazepate: a prodrug from the benzodiazepine series designed to dissociate anxiolytic and sedative activities.

Ethyl loflazepate (Victan) is an original 1,4-benzodiazepine (BZD) being used as a potent, nonsedative, minor tranquillizer. Ethyl loflazepate was designed to be a prodrug that would gradually release within the organism an active 1,4-BZD. It was hypothesized that this type of pharmacokinetic profile would dissociate anxiolytic from sedative activities. Previously published pharmacokinetic studies performed in rats, baboons and humans have confirmed that ethyl loflazepate gradually releases in the plasma an active 1,4-BZD, descarboxyloflazepate. In the present study, the activity of ethyl loflazepate and its main plasmatic metabolites were examined in rodent models predictive of anxiolytic, anticonvulsant, myorelaxant and sedative properties. The activities of ethyl loflazepate and its metabolites were compared to those of reference BZDs: diazepam, bromazepam, nitrazepam, flunitrazepam, lorazepam, clorazepate. Ethyl loflazepate and its metabolites revealed the typical profile of activity of minor tranquillizers. The activity of ethyl loflazepate was long-lasting. The overall anxiolytic potency of ethyl loflazepate was similar to that of diazepam but ethyl loflazepate appeared to be less sedative than diazepam. Thus in the approach-avoidance conflict procedure in rats the threshold anxiolytic doses were 1 and 2 mg/kg i.p. for ethyl loflazepate and diazepam, respectively, whereas the threshold sedative doses were 16 and 8 mg/kg i.p., respectively. In vitro ethyl loflazepate exhibited a weak affinity for the BZD receptor site. In vivo ethyl loflazepate displaced [3H]-flunitrazepam from mice brain membranes with a potency comparable to that of lorazepam. In vitro, descarboxyloflazepate, the main plasmatic metabolites of ethyl loflazepate, revealed a 4-fold greater affinity for the BZD receptor than diazepam.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

CM 40907: a structurally novel anticonvulsant in mice, rats and baboons.

CM 40907 [3-(4-hydroxypiperidyl)-6-(2'-chlorophenyl)-pyridazine] is a chemically original compound which possesses the pharmacological properties of a potent, p.o. active anticonvulsant. The anticonvulsant activity of CM 40907 was examined in mice, rats and photosensitive Papio-papio baboons and compared to that of phenobarbital, diphenylhydantoin, carbamazepine, sodium valproate and ethosuximide. In mice, CM 40907 antagonized electroconvulsive shock and chemically induced seizures with an overall potency comparable to that of carbamazepine and a therapeutic ratio (ED50 rotorod/ED50 electroshock) superior to that of ethosuximide, sodium valproate, phenobarbital and carbamazepine. In the rat CM 40907 suppressed completed kindled amygdaloid seizures and was approximately as active as phenobarbital. In naturally photosensitive Senegalese Papio-papio baboons CM 40907 antagonized myoclonus and cortical paroxysmal discharges. In this model CM 40907 was approximately one-fourth as potent as phenobarbital, twice as potent as carbamazepine and 6 times more potent than sodium valproate. In mice CM 40907, at anticonvulsant doses, increased the affinity of [3H]flunitrazepam for its central receptor site. Based on these results it is postulated that CM 40907 is a potent and relatively nonsedative anticonvulsant and may be of therapeutic benefit in epileptic disorders.

Animals↗
PubMed1985

Minaprine, a new drug with antidepressant properties.

Minaprine is a new psychotropic drug which has recently proved to be effective in the treatment of various depressive states. In rodents, minaprine exhibits an atypical spectrum of antidepressant and dopaminomimetic activities. Thus in mice minaprine antagonizes the effects of reserpine, decreases immobility time in the behavioural despair test and potentiates the effects of 5-HTP; in rats it antagonizes muricidal behaviour (blocked by PCPA or raphectomy). However, minaprine does not affect yohimbine lethality and does not induce anticholinergic effects in mice. Minaprine also activates central dopaminergic transmission. Thus at low doses the drug antagonizes neuroleptic-induced catalepsy and induces stereotypies in rats. These stereotypies are blocked by neuroleptics. In addition, minaprine (like apomorphine) induces contralateral turning in mice with a unilateral lesion of the striatum, whereas d-amphetamine induces ipsilateral rotations. Unlike classical dopaminomimetic drugs, minaprine does not stimulate locomotor activity in rats. The mechanisms by which minaprine exerts its effects are still unclear, since in vitro minaprine does not affect monoamine uptake or release and does not interact with monoamine receptors. In vivo, minaprine (acute doses) increases 5-HT, decreases 5-HIAA levels in various brain areas and weakly and reversibly inhibits type A MAO; subacute treatments lead to a decrease in the number of 5-HT1 and 5-HT2 receptors. In addition, in the striatum the drug decreases HVA and DOPAC, and increases 3-MT levels, without affecting DA levels. Minaprine also weakly displaces (3H)-spiperone from striatal D2 receptors and increases striatal ACh levels. Finally, minaprine fails to affect brain NA or MHPG levels in acute doses and does not modify beta receptor density in subacute treatment. Thus minaprine appears to be a chemically and pharmacologically original antidepressant drug which activates both 5-HT- and DA-mediated transmission but which is devoid of NAergic and anticholinergic effects. This latter statement is confirmed by the good cardiovascular tolerance of minaprine in dog, monkey and humans, and by the lack of "tricyclic-like" anticholinergic side-effects in man.

Acetylcholine↗
PubMed1984

Anticonvulsant activity of 4,9-dioxo-5,10-diazatetradecane (CM 40142), a new GABA derivative, in mice and photosensitive baboons).

The authors describe the anticonvulsant activity of a new gamma-amino-butyric acid (GABA) derivative in several animal models of generalized epilepsy including photoepileptic baboons. In all the studies, 4,9-dioxo-5,10-diazatetradecane (CM 40 142) revealed potencies against chemically, electrically and photic-induced seizures very similar to those observed with sodium valproate. In chemically elicited seizures in mice, CM 40142 exhibited a higher potency than sodium valproate in antagonizing anti-GABAergic agents. Although CM 40142 was synthesized as a compound which would cross the blood-brain barrier and liberate GABA within the central nervous system, preliminary biochemical investigations in mice failed to demonstrate a rise in brain GABA levels after treatment with CM 40142. Furthermore, CM 40142 increased spontaneous motility in mice at anticonvulsant doses. The data suggest that CM 40142 could be a broad spectrum nonsedative antiepileptic agent.

3-Mercaptopropionic Acid↗
PubMed1984

Two novel agents affecting eating through an action on monoaminergic systems.

The pharmacological effects of two newly synthesized anorectic agents CM 57373 (4-amino-1-(6-bromopyrid-2-yl) piperidine hydrochloride) and CM 57493 (4-(3-trifluoromethylphenyl)-1-(2-cyanoethyl)-1,2,3,6 tetrahydrophyridine hydrochloride) have been studied. Both drugs decreased food intake dose dependently in rats deprived of food for 20 h/d. The doses that inhibited food intake by 50 percent (ID50) were 9.74 mg kg-1 p.o. for CM 57493 and 7.37 mg kg-1 p.o. for CM 57373. The general behaviour of the rats was not affected at anorectic doses and no amphetamine-like stimulation was observed. The anorectic effect of CM 57373 was selectively, but not completely, antagonized by metergoline and methysergide, two antagonists of serotoninergic receptors in the central nervous system. Neither noradrenaline antagonists (propranolol and phentolamine) nor a dopamine antagonist (penfluridol) affected the anorexia induced by CM 57373. These results indicate that the anorectic effect of CM 57373 is, at least, partially mediated by the serotoninergic system. The mechanism of action of CM 57493 is more complex, since several distinct neurotransmitter systems appear to be involved in its effect. In cross-tolerance experiments with fenfluramine, there was a reduction of the anorectic activity of CM 57493, suggesting similar mechanisms of action for these two drugs, even though pretreatment with metergoline or methysergide antagonized the anorectic effect of fenfluramine but not that of CM 57493. The anorectic effect of CM 57493 was antagonized by pretreatment with propranolol, a beta-noradrenergic antagonist, suggesting an involvement for the beta-noradrenergic system as well. Pretreatment with phentolamine or penfluridol did not modify the effect of CM 57493 on food intake. In-vitro and in-vivo biochemical studies showed that CM 57373 and CM 57493 act mainly on central serotoninergic mechanisms. CM 57373 is a serotonin releaser and a serotonin reuptake inhibitor. But, unlike fenfluramine which affects the storage pool for 5HT, it releases 5HT mainly from a functional pool. CM 57493 did not affect serotonin release and uptake but exhibited a high affinity to serotonin postsynaptic receptors.

Animals↗
PubMed1983

Kappa binding sites in guinea-pig brain membranes: evidence for a dynorphin-resistant subtype.

Using [3H]ethylketocyclazocine after suppression of mu, delta and sigma binding by 100 nM DAGO + 100 nM DADLE + 10 microM phencyclidine we showed the existence of a subclass of kappa sites insensitive to dynorphins 1-9 and 1-17, and alpha and beta neoendorphins, but sensitive to the non-peptidic opiates. The dynorphin-sensitive site probably corresponds to the "standard" kappa site while the importance of the dynorphin-resistant site remains to be established.

Analgesics, Opioid↗
PubMed1982

Human melanoma cells can be killed in vitro by an immunotoxin specific for melanoma-associated antigen p97.

Conjugates (immunotoxins) comprising ricin A-chain and monoclonal antibody 96.5, which is specific for human melanoma-associated antigen p97, inhibited protein synthesis and colony formation of cultured human melanoma cells that expressed more than 80,000 molecules of p97 per cell. Cells expressing fewer than 5,000 molecules of p97 were not killed. The presence of 10 mM ammonium chloride significantly increased the efficiency of the immunotoxin, tumor cells expressing high levels of p97 being killed at immunotoxin concentrations as low as 10(-10) M.

Antibodies, Neoplasm↗
PubMed1982

Limited in vivo bioassays on some benzodiazepines: lack of experimental initiating or promoting effect of the benzodiazepine tranquillizers diazepam, clorazepate, oxazepam and lorazepam.

Four benzodiazepine tranquillizers were tested for their ability to initiate or promote the development of preneoplastic and neoplastic rat liver lesions. In comparison with the liver carcinogen, N-2-fluorenylacetamide, the benzodiazepines exhibited no initiating activity during a 14-week period of daily administration by gavage. To study the promoting activity, N-2-fluorenylacetamide was used to initiate altered foci and neoplastic nodules in rat liver during 8 weeks and then the benzodiazepines were administered by daily gavage for a period of 12 weeks. The liver tumor promoter phenobarbital had a substantial enhancing effect upon the persistence of nodules but none of the benzodiazepines showed a similar effect. Thus, in the process model systems used, to detect initiating or promoting potential effect, the benzodiazepine tranquillizers failed to exhibit either an initiating or a promoting action.

2-Acetylaminofluorene↗
PubMed1982

Analgesia, new research approaches.

In the field of research of new centrally acting analgesics devoid of side effects, two Quo Vadis? symposia took place in Montpellier and Toulouse. The first was devoted to a review of the concept of enkephalinase inhibition: a specific protease for enkephalin inactivation. The second dealt with the existence of a kappa receptor, one of the opiate binding sites whose stimulation would not involve a respiratory depression and only induce limited tolerance and dependence phenomena.

Analgesics↗
PubMed1982

Pharmacological evaluation of minaprine dihydrochloride, a new psychotropic drug.

Minaprine (3-[2-morpholino-ethlamino]-4-methyl-6-phenyl-pyridazine dihydrochloride; 30038CM; trade name in France: Cantor) is a new psychotropic drug. The therapeutic profile of minaprine differs from that of other known psychotropic agents; in man the drug antagonizes the "inhibitory syndrome" characterized by decreased spontaneous activity, reduction in basic drives, slowed thoughts, feelings of tiredness and social withdrawal. Preliminary clinical trials have indicated that minaprine may also be effective in certain depressive states. This finding prompted us to study the effects of minaprine in animal models for depression. Like most antidepressants minaprine antagonizes behavioral despair, but the effect exhibits a slow onset and maximal activity is reached 24 h after administration. Minaprine also antagonizes reserpine-induced ptosis, this effect has a rapid onset, and is long-lasting. In contrast, minaprine poorly antagonizes reserpine-induced hypothermia. Unlike most antidepressants minaprine does not potentiate yohimbine-induced lethality. Minaprine potently antagonizes prochlorperazine-induced catalepsy in rats and potentiates amphetamine-induced stereotyped behavior, suggesting that the drug may enhance dopaminergic transmission. Finally, minaprine does not antagonize either oxotremorine-induced tremors or physiostigmine-induced lethality. Taken together the results of the present study indicate that minaprine is active on certain, but not all, animal models for depression and suggest the drug may have a potential clinical utility in the treatment of human depressions.

Animals↗
PubMed1982

Mild insomnia induced by environmental perturbations in the rat: a study of this new model and of its possible applications in pharmacological research.

This paper describes an experimental model for testing new products in a situation where sleep is impaired by a nonpharmacological procedure. This model consists in studying the effect of hypnogenic substances on sleep perturbations which take place when chronically implanted rats are moved to a novel individual cage, connected for the first time to their recording cable and dosed intragastrically with test products, vehicle or placebo. Continuous polygraphic recordings were taken throughout the daily treatment period (15 days) and scored for the presence of slow wave sleep (SWS), and rapid eye movement sleep (REM). The hourly vigilance stages were also computed to determine the parameters of their nycthemeral rhythms. In vehicle-treated rats, a decrease in SWS and REM values and a delay of SWS and REM phases of nycthemeral rhythms occurred on the first day as compared with the end of the recording period. Phenobarbital (5 mg/kg p.o.), mecloqualone (5 mg/kg p.o.) and a new benzodiazepine CM 7302 (7 mg/kg p.o.) led to an immediate or fast recovery, whereas no improvement was observed with placebo and with clorazepate dipotassium (9 mg/kg p.o.). This model can be considered as an attractive model for studying mild insomnia because it allows "true" hypnogenic drugs to be selected in a minimum amount of time.

Animals↗
PubMed1981

The biotransformation of [14C]minaprine in man and five animals species.

1. [14C]Minaprine was administered as a single oral dose to five animal species and to a healthy and informed volunteer. Excretion of radioactivity was followed during 48 h in urine and faces; biliary excretion was followed only in rat. 2. Urinary metabolites were isolated and identified by mass spectrometry. 3. A quantitative comparison of metabolites in different species was made. On the basis of these data it it concluded that the dog is not a suitable model for man for pharmacological or toxicological studies. 4. The major metabolic route is 4-hydroxylation of the aromatic ring. The only unexpected metabolic route found was the biotransformation of the morpholino ring, probably by reductive ring-cleavage. 5. About 50% of the 14C was excreted in 0-48 h urine. The other 50% was excreted in the 0-48 h faces. In the rat, this was attribute entirely to biliary excretion. The drug is well absorbed after oral administration and is not accumulated in the body.

Adult↗