Biomedical subjects
Publications and source records attributed to M Gonce.
Clinical and electrophysiological data are reported on two patients presenting with unusual reflex myoclonus triggered specifically by exteroceptive stimulation.
The definition and classification of tics is still based on clinical data. Furthermore, in Gilles de la Tourette syndrome, organogenetic and psychogenetic determinants are still opposed and the true automatic involuntary nature of tics is still debated. Neurophysiological assessments can provide objective data, useful in analysing the physiopathology of tics. Simple tics consist of short bursts of EMG activity (lasting usually less than 100 ms) whereas complex tics consist of prolonged EMG activity. In both cases, the reciprocal activation of antagonist muscles may be present or absent. EEG recording has revealed abnormalities in about 25 to 75 p. 100 of Gilles de la Tourette patients but these findings lack specificity. Furthermore there is no EEG-EMG correlates with conventional techniques. However Obeso et al. have shown that simple tics are not prefaced by a normal premovement EEG potential, suggesting that simple tics are physiologically distinct from normal self-paced willed movements. Overnight polygraphic sleep studies show perturbation of the normal sleep pattern and stress the fact that tics may persist during all stages of sleep. Thus electrophysiological assessments give clues to the classification of tics as true abnormal automatic movements but also demonstrate their diversity. A biochemical cortico-subcortical dysfunction can be postulated.
Pergolide is thought to stimulate both D1 and D2 dopaminergic receptors. Its effects on Parkinson's disease were evaluated in an open trial, using clinical assessment scales and objective tests. Nine patients had previously been treated with L-dopa, but the drug had either gradually lost its effectiveness or produced invalidating side-effects. Pergolide in doses of 2 mg per day considerably and durably improved the parkinsonian symptoms and enabled the patients to reduce L-dopa dosage by about 50%. Dyskinesia and "on-off" phenomena partially regressed. Significant improvement was also observed in 3 of 4 patients with Parkinson's disease who had not previously received L-dopa. The side-effects of pergolide were fairly frequent in both groups, but they were relatively mild and reversible.
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We have studied the brain regional distribution of methyl mercury following intravenous administration of CH3 203HgCl in rat. Early peak levels were obtained in cerebellum, medulla oblongata and midbrain. The efficacy of removal of 203Hg by different chelators is also region dependent. The most efficient chelator for brain mercury proved to be mesodimercaptosuccinic acid.
The writers present some physiological (and not therapeutic) acute and sub-acute trials with tripeptide: L-propyl-L-leucyl-glycine amide (M.I.F.-I) in Parkinson's Disease. This work confirms the earlier observation that M.I.F.-I employed alone or in combination with Levodopa is active against Parkinson's disease. The writers evoke the hypothesis that this action takes place at the postsynaptic receptors, whose configuration may be modified in the sense of a hypersensitivity. These studies justify undertaking a series of controlled therapeutic trials when the cost of the product permits and as well instituting development work on analogues active orally.
Electrophysiological studies of the nociceptive reflex (R3) were carried out in eight normal subjects, and one patient with congenital insensitivity to pain, in order to compare the effects of naloxone and a placebo. No significant variation in the reflex threshold was seen in the normal subjects. Two electrophysiological abnormalities were observed in the patient: a 350 per cent spontaneous elevation in the R3 threshold compared to the control group; a rapid and large drop (67 per cent) in the threshold lasting for about ten minutes after the injection of Naloxone. These results suggest that in this particular case the insensitivity to pain could be related to the permanent hyperactivity of a morphine-like inhibitory system.
The histories of seven consecutive cases of Gilles de la Tourette's syndrome are presented to exemplify the range of clinical manifestations in this disease and to collate preliminary results with the new benzodiazepine, clonazepam, as possible adjuvant therapy of this disorder. Controlled trials with clonazepam alone and in association with haloperidol are now justified. Five of our 7 patients had a positive family history of tics, and 2 a confirmed family history of gout. Because clonazepam improves myoclonia and tics and because its mechanism of action possibly involves serotonin, we thought it worthwhile to study simultaneously the relative roles of serotonin and dopamine metabolism in the production of tics, and their relationship to possible defects in purine metabolism in Gilles de la Tourette's syndrome.
Uptake of 14C-dopamine by human platelets has been studied in two diseases, namely Gilles de la Tourette's syndrome and Huntington's chroea, in which abnormal metabolism of dopamine has been implicated. Platelets from untreated Huntington's chorea patients showed a small increase in Km and Vmax.; platelets from patients in all other groups showed an uptake identical with the controls. Haloperidol (10(-5)M) was also shown to be a strong non-competitive inhibitor of 14C-DA uptake by platelets. This property is probably unrelated to the drugs' action in ameliorating the symptoms of Huntington's chorea which is likely related to the increase in cholinergic neuronal activity produced by neuroleptic blockade of dopamine receptors.
We have reviewed the aetiology, symptomatology, biology and clinical course of 61 cases of the Gayet-Wernicke encephalopathy. Our results do not differ fundamentally from those of Victor et al. (1971). Nevertheless, our study shows fewer oculomotor palsies in the acute stages, lower mortality and a lower incidence of residual anmesic syndromes. These results demonstrate the importance of early diagnosis and of starting the specific therapy in the initial stage of reversible biochemical lesions.
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This paper reviews recent evidence that a number of small peptides found in the brain are active in the central nervous system and behaviorally. Attention is focused on MSH/ACTH 4-10, alpha- and beta-MSH, and the prohormone beta-LPH, as they produce a syndrome of yawning and stretching. Studies with substance P and mainly with MIF-I are also reviewed. It is shown that substance P is an excitatory transmitter or modulator in the dorsal spinal cord with that MIF-I has antiparkinson properties. It is concluded that many polypeptides have direct actions on the central nervous system independent of their neuroendocrine properties.
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Veratramine produces a characteristic excitatory action on the central nervous system, producing both tremor and a characteristic "struggling" behavior. This behavioral excitation is accompanied by changes in serotonin content in hypothalamus. The central serotonin agonist methysergide in doses of 5--15 mg per kg produces a dose-dependent inhibition of veratramine's action, while parachlorophenylalanine has no effect. These results are consistent with a serotonin agonist mechanism to explain veratramine's action.