Search PubMed⌕ Search

Biomedical subjects

H Allain

Publications and source records attributed to H Allain.

At least 91 records · Page 5Linked to original sources
PubMed1994

Monoamine oxidase inhibitors, cognitive functions and neurodegenerative diseases.

Recent data obtained in animals and in humans suggest that both MAO-A and MAO-B inhibitors present cognitive enhancing properties of possible interest in the treatment of cognitive disorders. In addition, the rational for using selegiline as a neuroprotector in Parkinson's disease may also be applicable in Alzheimer's disease in which a dramatic increase in the MAO-B activity has been reported. It seems then worthwhile to investigate the neuroprotective effect of MAOIs in humans and to assess, furthermore, the real therapeutical benefit of their cognitive enhancing properties.

Alzheimer Disease↗
PubMed1994

Temporal profile of aminergic neurotransmitter release in striatal dialysates in rats with post-ischemic seizures.

The temporal profiles of aminergic neurotransmitter levels and of their acid metabolites after transient global cerebral ischemia in awake rats with and without subsequent seizures were compared using a microdialysis approach. In seizure animals, the post-ischemic levels of dopamine and serotonin were higher than the levels observed in the non-seizure controls. Inversely, the levels of the three neurotransmitter metabolites increased rapidly in the controls but not in seizure animals, where they remained at the low levels observed during and immediately after ischemia. This particular pattern is similar to that observed in rats submitted to prolonged ischemia or pretreated with monoamine oxidase inhibitors. In the seizure animals, neurotransmitter metabolites remained at low levels, as if the hypoxia had continued after the period of ischemia, inhibiting monoamine oxidase activity and, perhaps, neurotransmitter recapture.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1994

Inhibitor effects of diltiazem, nicardipine, nifedipine and verapamil on the norepinephrine-induced contractions of the canine saphenous vein in calcium-free medium.

Contractile responses to norepinephrine (noradrenaline, NE 10(-5) M) in the canine saphenous vein (SV) are significantly, although slightly, reduced (14%) when induced in a physiological medium depleted of calcium for 1 hour (+ EGTA). In contrast, they are inhibited by about 75% after 24 hr in calcium free physiological saline solution (P.S.S.). ED50 of norepinephrine in 1-hr calcium-free medium and in normal Ca++ P.S.S. are 6 x 10(-7)M and 4.2 x 10(-7)M, respectively. Two blockers of extracellular calcium entry have also been cited as inhibitors of intracellular calcium pool refilling. At concentrations of 10(-6)M, 10(-5)M and 10(-4)M, diltiazem and nicardipine inhibit the norepinephrine-induced contractions (NIC) in a concentration-dependent manner. At 10(-4)M, the two calcium blockers inhibit the NIC by 70% and by 72% respectively in Ca++ free (+ EGTA) P.S.S. Nifedipine and verapamil only begin to significantly inhibit NIC in Ca++ free (+ EGTA) P.S.S. at concentrations equal to or greater than 10(-5)M. At 10(-4)M concentration, control inhibition in Ca++ free P.S.S. was observed as 60% and 49%, respectively. Contrary to the other 3 calcium antagonists tested, diltiazem antagonises NIC significantly less in calcium-containing medium (45%) than in calcium-free medium (72%). Procaine at a concentration of 10(-3)M, described as sufficient to totally inhibit calcium release from its intracellular storage sites, only inhibits NIC by 52% in calcium free (+ EGTA) P.S.S. These results are consistent with the following conclusion: i) in the canine saphenous vein (SV), NIC is mainly mediated by calcium mobilization from its intracellular storage sites; ii) the calcium antagonists tested here and procaine are unable to totally inhibit, even at high concentrations, the contractions induced via intracellular calcium release; this characteristic is nonsignificant for nifedipine and verapamil at low concentrations (10(-6)M). iii) verapamil and nifedipine, like diltiazem and nicardipine at high concentrations, may not only possess the characteristics of extracellular calcium entry blockers, but also that of partial antagonist of NIC via non specific mechanisms; iv) diltiazem may relax the vascular smooth muscle of SV, not only by the above two properties, but also through another mechanism yet unknown; v) partial persistence of NIC on the SV under conditions of short or long extracellular calcium depletion may be due to a mechanism of intracellular Ca++ recycling, the smooth muscle cell partially retaining its intracellular Ca++.

Animals↗
PubMed1993

Symptomatic effect of selegiline in de novo Parkinsonian patients. The French Selegiline Multicenter Trial.

The French Selegiline Multicenter Trial was carried out in 1990 to investigate whether the disability of de novo patients with parkinsonism could be improved during the first 3 months by monotherapy with selegiline (10 mg/day). A double-blind, randomized, placebo-controlled clinical trial was conducted over 3 months with 93 patients from 13 centers. Symptomatology was assessed on various disease rating scales, including Hoehn and Yahr, Hamilton Depression Rating Scale, Unified Parkinson's Disease rating scale, and Schwab and England scores, as well as self-assessment. Biological and clinical parameters were measured for tolerability, and efficacy was investigated with special reference to the point at which therapy with L-dopa had to be started. Selegiline was significantly superior to placebo on the various motor rating scores, and depressive scores were significantly improved at the end of 3 months. Adverse effects were rare and minor. Therefore, selegiline could be the therapy of choice for the treatment of de novo parkinsonian patients.

Activities of Daily Living↗
PubMed1993

L-type voltage-dependent calcium channels do not modulate aminergic neurotransmitter release induced by transient global cerebral ischaemia: an in vivo microdialysis study in rat.

Cerebral ischaemia induces considerable neurotransmitter exocytosis, mediated by calcium entry in neurones, essentially via the N-type, voltage-dependent channels, which are insensitive to calcium blockers. Nonetheless, these blockers, by unclear mechanisms, exert a neuroprotective effect when used in experimental ischaemic models. On the other hand, the existence of L-type, voltage-dependent channels, the only ones responding to the action of calcium blockers on synapses, argues in favour of their possible concomitant action in certain highly pathological situations. We studied the action of three calcium blockers, nimodipine, diltiazem and verapamil (administered at a concentration of 100 microM directly into the striatum of rats), on the extracellular release of dopamine and serotonin, and on the level of their main metabolites, in a model of transient global cerebral ischaemia (four-vessel occlusion). The total absence of effect of these molecules on neurotransmitter release induced by ischaemia proves the non-involvement of this mechanism in the protective action of calcium entry blockers on ischaemic lesions, and the absence or very weak action of L-type, voltage-dependent presynaptic channels in the striatum of rats.

Animals↗
PubMed1993

Alteration of aminergic neurotransmitter release after two consecutive transient global ischaemias: an in vivo microdialysis study in rat.

This study was designed to evaluate the effects of two consecutive ischaemias on extracellular monoaminergic neurotransmitter concentrations. The data on the neuroamine changes induced by the second ischaemia could be used to assess the delay in aminergic neurotransmission subsequent to the primary injury. Dopamine (DA), serotonin (5HT) and their metabolites, homovanillic acid (HVA), dihydroxyphenyl-acetic acid (DOPAC) and 5-hydroxyindolacetic acid (5-HIAA) were measured in vivo through striatal microdialysis of awake rats, using HPLC and electrochemical detection. Pulsinelli and Brierley's four-vessel occlusion model was used to induce a 20-minute global transient ischaemia in the forebrain. Two experimental groups were formed: the second ischaemic period was induced 3 h after the first one in group I (n = 5) and after 24 h in group II (n = 5). Dramatic increases in DA (150 times the baseline level) and 5HT (10 times the baseline level) were recorded during the first ischaemia, consistent with literature data. Metabolites of DA and 5HT (HVA and 5HIAA) decreased significantly. Baseline values were restored after 40 min of reperfusion. There was no significant difference between the effects of the first and second ischaemias on neurotransmitter release in group I. In group II, the second ischaemia did not significantly alter the baseline aminergic neurotransmitter content, although all the clinical signs of global ischaemia were present (in particular the loss of righting reflex). These original data could be explained by delayed impairment of release mechanisms, rather than by exhaustion of the releasable pools of these neurotransmitters one day after the first ischaemia.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1992

Reversal of learning and memory impairments following lesion of the nucleus basalis magnocellularis (NBM) by concurrent noradrenergic depletion using DSP4 in the rat.

In the following study the behavioural effects of simultaneous lesion of the nucleus basalis magnocellularis (NBM) using ibotenic acid and noradrenergic depletion following a single i.p. administration of DSP4 (50 mg/kg) were examined in the rat. NBM lesion induced a deficit in acquisition of a reinforced T-maze alternation task, a working memory adaptation of a spatial navigation task in a water maze and 24 h retention in a passive avoidance task compared to sham controls. No effect of the lesion on a reference memory version of spatial navigation in a water maze task was found. Animals that received a combination of NBM lesion and DSP4 treatment showed no impairment on any of the tasks that were impaired by NBM lesion alone. This indicates a reversal of the learning and memory deficits consequent to NBM lesion by simultaneous noradrenergic depletion. NBM lesion induced a significant reduction in choline-acetyltransferase activity in the frontal cortex, and DSP4 induced a significant decrease in noradrenaline concentration in occipital cortex and hippocampus, confirming the effects of these treatments. These results suggest an interaction between central noradrenergic and cholinergic systems in learning and memory processes.

Adrenergic Agents↗
PubMed1992

[Memory deficit in Parkinson's disease. Precocious aging of recall processes].

In this study, the various components of the memory process were analysed in 25 non-demented parkinsonian patients (PP). A battery of tests was used to explore words, drawings and semantic organization of items. Results were compared with young (n = 22) and elderly (n = 11) healthy controls. Scores were correlated with the characteristics of Parkinson disease. Recall of words and drawings was significantly disturbed in PP. In contrast, the recognition of drawings and faces was not impaired. A high degree of interindividual difference in performance was observed; it was strictly correlated with age but not with the features of parkinsonism. A specific pattern of memory impairment can be described in parkinsonism, which would suggest and support the theory that different pathogenic mechanisms are involved in ageing and in parkinsonian patients.

Adult↗
PubMed1992

Antidepressants and cognition: comparative effects of moclobemide, viloxazine and maprotiline.

The respective effects of three antidepressant drugs (moclobemide, 450 mg/j; viloxazine, 300 mg/j; maprotiline, 150 mg/j) on vigilance, attention, and memory were compared. Young depressed outpatients (n = 46) entered a double-blind, randomized, monocentre clinical trial lasting for 6 weeks. Drug actions were assessed through the regular determination of critical flicker fusion point (CFF), reaction times (SRT), and a battery to measure memory components. None of the three drugs caused deterioration in cognitive functions. On the other hand, moclobemide improved both vigilance and attention (CFF, SRT) and some crucial components of memory (general memory scores, delayed word recall, recognition of familiar faces). This effect was rapid, stable, and superior to those of viloxazine and maprotiline. It may be explained by moclobemide's selective and reversible inhibition of monoamine oxidase A, as well as by the lack of any anticholinergic action.

Adult↗
PubMed1992

[Pharmacology of cellular ischemia].

Knowledge of cellular disturbances provoked by an ischemic aggression conditions the use of a pharmacologic strategy that could possibly protect the cell from necrosis. Whatever the type of cell, the basic mechanisms are very similar: energy failure, acidosis, loss of electrolytic homeostasis, particularly of calcium, formation of free radicals and, of more recent knowledge, genetic induction. Different molecules have been shown to be effective at each of these stages in one or other of the many experimental models available. The therapeutic approach is not very forthcoming at present but the field of applications is vast. Ischemic disease is not restricted to cerebral or cardiac ischemia and, although the lesions are mainly those of senescence, it is observed in other etiologic frameworks, if only in the perinatal period. Finally, the great increase in the use of organ transplants opens up another field of application with research on the best method for organ preservation and optimization of its acceptance by the host organism.

Animals↗
PubMed1992

Newly evidenced pyrimidinoceptors and the P2x purinoceptors are present on the vascular smooth muscle and respectively mediate the UTP- and ATP-induced contractions of the dog maxillary internal vein.

P2 purinergic receptors and pyrimidinoceptors were studied by comparing the contractile responses to UTP with those to ATP, in the dog internal maxillary vein (IMV) after endothelium removal. The contraction curves were very different: rapid subsidence with ATP and sustained contraction with UTP. alpha beta methylene ATP induced desensitization to ATP, whereas it did not antagonize the UTP-induced contractions. Reactive blue 2 (RB2) was incapable of antagonizing contractions to ATP and UTP in this vessel. We showed that Nicardipine, a calcium antagonist, was more potent on the UTP-induced than on the ATP-induced contractions. The fact that RB2 did not potentialize the UTP-induced contractions, unlike what has been observed in the dog saphenous vein, suggests that a new category of pyrimidinoceptors have been evidenced on the IMV. Our results also indicate that ATP induces contraction via P2x rather than P2y purinoceptors. The receptors described here are localized on the vascular smooth muscle.

Adenosine Triphosphate↗
PubMed1991

Postmarketing surveillance of zopiclone in insomnia: analysis of 20,513 cases.

The subjective response to the prescription drug zopiclone, an hypnotic agent belonging to the cyclopyrrolone family, was assessed under the usual conditions of prescription of an hypnotic in general practice. The study included 20,513 insomniac outpatients with at least two of the following symptoms: sleep onset latency longer than 1 hour, more than two nocturnal awakenings, early morning awakening 1 hour or more before scheduled time, total sleep time of less than 6 hours, complaint of tiredness on awakening. Insomniac patients were treated with zopiclone and followed for 21 consecutive days within the context of a follow-up surveillance study. The population was predominantly female (62.6%), and the mean age was 52.3 years. The dosage of zopiclone prescribed at the inclusion visit was 7.5 mg per day in 87.5% of the cases and 3.75 mg per day in 10.5%. A total of 93.8% of the patients completed the survey. Spiegel questionnaire improved during the 21-day survey, and 9.2% of the patients reported at least one adverse event that led to treatment discontinuation in only 2.8% of the population. No serious or unexpected adverse events were reported.

Adolescent↗
PubMed1991

Cardiac beta-adrenoceptor sensitivity and Parkinson's disease.

Certain clinical manifestations of Parkinson's disease (PD) (speech or/and balance disturbances) are not linked to brain dopamine deficiency. The purpose of the present study was to search for a possible relationship between those so-called "non-dopamine-dependent" extrapyramidal manifestations and the sensitivity of cardiac beta-adrenoceptors. Fourteen patients aged 51 to 69 were included in the study after having given their informed consent. Any factor or pathology susceptible to modify receptor sensitivity entailed exclusion. In the absence of a reference model for measuring the reactivity of central beta-adrenoceptors, a computation of the isoprenalin dose necessary to increase the resting heart rate by 20 bpm was used as an index for beta-adrenergic system reactivity. In addition to that test, other parameters were recorded: disease duration, motor status scale (Columbia), some cognitive functions (MMS and image differed recall). The cardiac beta-receptor decrease in reactivity to isoproterenol is correlated to PD duration (r = 0.8, P less than 0.001). Conversely, the sensitivity of these receptors appeared to be unrelated to the extrapyramidal severity of the disease, hence to the degree of the so-called "non dopamine-dependent" disturbances. Furthermore, such results raise the meaning of the impairment of peripheral aminergic receptors in the cognitive disturbances linked to ageing and/or PD.

Aged↗
PubMed1991

Selegiline in de novo parkinsonian patients: the French selegiline multicenter trial (FSMT).

The French selegiline multicenter trial was conducted in 1990 to test the possibility to improve disability of de novo parkinsonian patients (P.P.) during the first three months of treatment with selegiline (S) (10 mg/day) monotherapy. 93 P.P. were included in this double-blind, randomized, placebo controlled, clinical trial, in which 13 centers participated. Both parallel groups were followed up from inclusion (D0) to D30, D60 and D90. Drug efficacy was judged with Hoehn and Yahr (HY), Hamilton Depression Rating Scale (HDRS), Unified Parkinson's Disease Rating Scale (UPDRS), Schwab and England scores, decision to introduce levodopa and selfassessment. Biological and clinical parameters (cardio- vascular, weight, side-effects reports) were assessed for tolerability. 84 P.P. (38 P, 46 S) were evaluable for efficacy at D90. When considering the main parameters, S appears superior to placebo: HY scores (p less than 0.001), global UPDRS scores (p less than 0.001) and UPDRS subscores: mental (p less than 0.001), daily living activities (p less than 0.01), motor activities (p less than 0.01). Depressive scores (HDRS) are significantly improved only at D90 (p = 0.005). Levodopa therapy was introduced in 45% of the cases in S groups versus 18.4% in P group. Global impression of efficacy was largely in favor of S; failure was noted in half of the cases in P group and only in 1/5th of the cases in S group. Side-effects were rare and minor. S 10 mg/day monotherapy is statistically superior to placebo in improving de novo P.P. during the first three months treatment. Motor symptoms rapidly improve; mood is only modified after 3 months. S appears to be well tolerated. S may be considered as a good candidate for the initial treatment of P.P.

Aged↗
PubMed1991

[Anxiolytic agents and hypnotic drugs in Bretagne. Pharmaco-epidemiological study].

A pharmacoepidemiological survey was carried out in a rural region of France (Brittany) with the help of 54 general practitioners, all of whom belong to a clinical research group. The aim of the survey was 3-fold: to determine the frequency (incidence and prevalence) of anxiolytic and hypnotic drug prescriptions, the sociological characteristics of these drug consumers, and the indications and reasons for prescribing this class of drugs. The population of hypnotic drug and sedative consumers was strikingly dominated by women, 60 years old and over, retired or without a profession. Prescription analysis revealed that these drugs were essentially benzodiazepines whose prevalence and incidence were 17 and 1.76%, respectively. A high frequency of prescription renewals (78%) and an elevated percentage of long-term treatments (more than 9 years) were also noted. Insomnia and dependence are the two main "risk factors" for drug treatments lasting more than one year.

Adult↗
PubMed1991

Comparison of three regimens of Parlodel-SRO in levodopa-treated parkinsonians: a randomized double-blind crossover study.

Parlodel-SRO is a newly developed slow-release formulation of bromocriptine, which prevents initial plasma peak--a known source of adverse events--and extends the half-life of the compound, an interesting feature for the management of motor symptoms in Parkinsonians. This study was designed to determine the best daily administration schedule for 30 mg Parlodel-SRO in 18 parkinsonians previously treated with levodopa and standard Bromocriptine (Br). The 30 mg dose was replaced from one day to the next, in a randomized, double-blind latin square design trial. Three consecutive 7-day courses were implemented, during which a total daily dose of 30 mg P-SRO was administered in one dose, two intakes (b.i.d.) and three intakes, (t.i.d.) respectively. The b.i.d. schedule produced the best improvement in UPDRS scores, especially as to postural stability, walking, bradykinesia; it also provided greater pharmacological stability throughout the assessment day. Adverse event analysis was not in favor of a single daily dose. It appeared that P-SRO administered in two 15 mg intakes (morning and evening) produces the best benefit-risk ratio in Parkinsonians who were already being treated with levodopa.

Adult↗
PubMed1990

[Hydroxylation of debrisoquin in Parkinson's disease].

The accumulation of environmental substances, due to deficiency of liver detoxication processes, is one of the hypotheses put forward in the search of the cause of Parkinson's disease. The debrisoquine test was used to evaluate the capacity for hydroxylation of twenty patients treated for Parkinson's disease. No difference was found with the results obtained in non Parkinsonians: other metabolic pathways, notably S-methylation, should be explored.

Adult↗