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M Lamarche

Publications and source records attributed to M Lamarche.

At least 37 records · Page 2Linked to original sources
PubMed1986

Penicillin epileptogenic focus in the rat: requisites for transcortical reflex triggering.

Epileptiform discharges elicited by natural or electrical stimulations, proprioceptive or cutaneous, were studied in the rat with an experimental acute focus induced by penicillin application in the motor area. EEG paroxystic spikes were easily triggered with restricted foci (0.5 to 1 mm2) located in the representation area of the stimulated region. However, despite the large overlap of sensory and motor cortical limb areas in the rat, EEG spikes, either spontaneous or triggered, were followed by muscular jerks only with much larger foci: at least 2 and 4 mm2, respectively, for anterior and posterior limb areas. Cutaneous stimulations were the most efficient in discharge production; however, discharges were triggered indifferently by muscular or cutaneous afferent fibers in about three-fourths of the cases. The temporal relation between EEG spike and myoclonic jerk were very close. A latency analysis (delay between triggered EEG spike and EMG response, parallel latency fluctuation of both phenomena, delay between spontaneous EEG spike and jerk) supported the hypothesis that a transcortical reflex mechanism, rather than a spinal excitability rebound, was involved in the jerk genesis. Iontophoretic ejection of penicillin within layers III-IV resulted in the development of electroclinical paroxysms. However, similar penicillin ejection within layer V, did not allow efferent discharge production. It is concluded that the involvement of a large surface or volume of cortical tissue is required to produce efferent discharges following EEG paroxysms. This observation is likely related to the unexpectedly wide representation of individual muscles at the motor cortical level.

Animals↗
PubMed1985

A reappraisal of rat motor cortex organization by intracortical microstimulation.

The organization of the motor cortex was reinvestigated with intracortical microstimulation, in light-anaesthetized (ketamine) rats. A posterolateral (PL) vibrissae area was found in addition to the rostral one, and blinks of the contralateral eyelids were elicited from a part of this PL area. Several cortical representations such as neck or tail were largely overlapping with neighbouring areas. Vegetative effects (mainly myosis and swallowing) were obtained from a medial cortical strip. Within the PL vibrissae area, a topical arrangement related to the vibrissal rows was observed, whereas in the leg areas, no individual representation of muscles could be evidenced. These results are compared with the maps previously published, and discussed in terms of specificity, musculotopy and overlapping of motor areas.

Animals↗
PubMed1984

[Nasogenial flaps].

A large epidermoid carcinoma of the lower lip in an elderly patient was treated by excision followed by reconstruction by means of a double nasogenial flap. The postoperative course was complicated by necrosis and then rejection of the flap. Spontaneous healing assisted by local treatment produced a satisfactory functional as well as esthetic result.

Aged↗
PubMed1983

The transcortical reflex triggered by cutaneous or muscle stimulation in the cat with a penicillin epileptic focus: relative importance of regions 3a and 4.

After establishment of a cortical penicillin epileptic focus in the cat, stimulation of an anterior paw muscle can evoke a late myographic response (LMR) in the same muscle via a transcortical reflex. It is shown here that (1) an LMR can also be obtained with cutaneous stimulation in the region of the muscle; (2) an LMR cannot be elicited when the focus in on area 3a; (3) after inactivation of area 3a by TTX, the motor cortex evoked potential and spike thresholds are increased for proprioceptive but not for cutaneous stimulation, and the LMR persists. It is concluded that area 4 is the critically important structure for the triggering of an LMR. The results concerning area 3a are discussed in terms of this region's efferent connections to the motor cortex and to the spinal cord.

Afferent Pathways↗
PubMed1982

[Proprioceptive afferents of the transcortical reflex in motor epilepsy:localisation of their thalamic relay in the cat (author's transl)].

In the Cat with a penicillin motor focus, a transcortical reflex (RTC) can be triggered by stimulation of the muscle or the cutaneous branch of the radial nerve (DR - SR). We tried here to identify at a suprabulbar level, the proprioceptive pathway involved in triggering RTC. Cerebellar ablation did not modify the reflex. On the other hand reversibly inactivation of a rostral-dorso-medial part of VPL (VPLr) receiving short latency proprioceptive afferents, reversibly abolished the TRC elicited through DR stimulation, while SR stimulation was still effective. It is thus assumed that muscle and cutaneous afferents responsible for eliciting the RTC run in parallel pathways with distinct relay zones within the VPL nucleus.U

Afferent Pathways↗
PubMed1981

Modulation of proprioceptive transcortical reflexes in the cat with a penicillin epileptic motor focus.

Mechanisms responsible for the triggering of paroxysmal events by proprioceptive afferents, previously described in the monkey with a chronic epileptic focus, were studied in more detail in the cat with a penicillin focus. To analyse the topical organization of this reflex triggering, the focus was restricted to very small areas of the motor cortex; in this study only pericruciate areas were considered in which stimulation elicited a motor response in one of the several forelimb muscles tested, and which received afferents from that muscle. When the focus was located in the post-sigmoid gyrus, stimulation (usually by stretch) of the given (target) muscle first elicited a cortical spike following the evoked response, and secondly a late phasic EMG response (about 40 msec latency) quite distinct from purely spinal reflexes. Cortical spikes and late EMG responses were closely correlated, especially considering their probability of occurrence or their parallel latency fluctuations. In most cases, this effect was limited to the muscle whose motor area had been treated with penicillin: stretching muscles in the vicinity was ineffective, nor were these muscles activated when the target muscle was stimulated. Evidence is given for the participation of a transcortical reflex in the generation of the late phasic response and for the involvement of the pyramidal tract in this reflex.

Animals↗
PubMed1981

[Transcortical reflexes of proprioceptive origin and motor epilepsy (author's transl)].

The long-loop reflex involved in the triggering of paroxysmal activities by proprioceptive afferents is examined in monkeys with a chronic alumina focus and in cats with an acute penicillin focus. Electrical stimulation of a tibial nerve in monkeys as well as muscle stretch in cats elicit a cortical 'evoked spike', i.e., an evoked potential followed by an epileptic spike, accompanied by one or two motor bursts in the muscles concerned. With a very small acute focus, this transcortical reflex is shown to be quite topical: muscles in the vicinity are not affected. Relationships between evoked spike and myoclonic jerk are examined and it is shown that motor efferents usually follow the pyramidal tract. The concept of a transcortical reflex of proprioceptive origin is discussed on the basis of data collected from these models.

Afferent Pathways↗
PubMed1981

[About five cases of cervico-facial actinomycosis (author's transl)].

Concerning five observations of cervico-facial actinomycosis in two hospital wards, the authors recall that this pathology, although rare, still exists. It appears as a chronic cellulitis, usually occurring among subjects lacking in dental hygiene. The authors insist on the necessity of asking for a bacteriological test by taking a sample of pus with a pipette to look for the responsible actinomyces. The cure consists in the extracting of the teeth concerned, the removal of the necrosed tissues, a drainage, and an antibiotic treatment based on high doses of Penicilline for about three months.

Actinomycosis, Cervicofacial↗
PubMed1979

[Phalloidian toxins].

The phalloidian toxins are very complex. The classification proposed by Wieland distinguishes between the various amatoxins and phallotoxins. The authors study successively: Methods of isolation, the general structure and chemical composition, their localization and concentration in mushrooms. This is an analytical study of the phallotoxins and amadoxins. Various experimental intoxication protocols using total extracts of the toxins purified with different doses and different animals have revealed the main signs of experimental intoxication with phallotoxins. This is characterized especially by hepatic and renal lesions. The phallotoxins have a more specific action on the cell membrane and metabolism. The amatoxins have a more specific action on the cell nucleus and protein synthesis. The action on DNA dependent RNA polymerases is particularly characteristic.

Amanita↗
PubMed1978

Movement epilepsy in the monkey with an experimental motor focus.

In the monkey with an alumina focus in the primary motor area, proprioceptive afferents are crucial in triggering or modulating seizures. The reversible exclusion of these afferents by curarization results, depending on the level of activity of the focus, either in regularization of spontaneous seizure frequency and duration (recorded from the cortex), or in their subtotal suppression. In the last case, muscular stimulation is still able to elicit seizures. The triggering modality is highly specific: if it is possible to induce seizures with acoustic or cutaneous stimuli in normal conditions, this is no longer possible under curare. It may then be assumed that exteroceptive stimulation is effective through the startle reaction or flexion reflex that they elicit; in other words, the actual trigger would take origin in the indirect involvement of proprioceptive afferents. Physiological mechanisms and relations with human clinical features are discussed.

Animals↗
PubMed1976

[Experimental study of the sensitizing properties of halothane].

The sensitizing properties of halothane were investigated experimentally in guinea pigs using two different techniques. The first method, derived from that of DRAIZE, included a sensitizing phase in which the product was administered by inhalation, while the second method, derived from that of MAGNUSSON and KLIGMAN, used guinea pigs sensitized to FREUND's adjuvant and which were sensitized to halothane administered subcutaneously. The results obtained in these two series of experiments appeared concordant. They showed that effective sensitization occurred in 60 to 80 p. 100 of the animals treated. This places halothane between level 3 (moderate potency) and level 4 (high potency) on the classical drug scale of "allergenic potencies".

Anesthesia, Inhalation↗
PubMed1976

[Technics for the experimental study of delayed hypersensitivity].

The author reviews the principal experimental methods proposed for the study of the sensitising power of medications. All these methods involve delayed hypersensitivity (Type IV) and fall into the same broad category, with a sensitisation phase, a rest phase and a stimulating phase. A critical review of these various phases is made; together with the interpretation of the results and their significance.

Adjuvants, Immunologic↗
PubMed1976

[Experimental study of the sensitizing power of methoxyflurane].

Methyoxyflurane, a halogenated general anaesthetic, showed a net sensibilizing effect in the guinea-pig when tested experimentally by the Magnusson and Klingman technique. According to these authors classification it may be classed as of "moderate allergenicity". In addition, the sensibilisation reaction obtained is prolonged. It remains at a similar level for 2 to 7 weeks after the end of the sensibilisation phase.

Animals↗