Search PubMed⌕ Search

Biomedical subjects

P Gauthier

Publications and source records attributed to P Gauthier.

At least 55 records · Page 3Linked to original sources
PubMed1995

Laparoscopic staging of early ovarian cancer.

The relevance of staging in early ovarian carcinoma is reviewed in light of the advances in surgical laparoscopy. Data from the literature suggest that a lymphadenectomy should be performed instead of a sampling. We have realized the former through laparoscopy. In this paper we propose a detailed surgical technique, similar to the laparotomy approach, that ensures an adequate nodal evaluation. Ten patients underwent a completion of staging by laparoscopy, including peritoneal washings for cytology, peritoneal and ovarian biopsies, an infracolic omentectomy, and a lymph node dissection. The use of laparoscopy for staging of early ovarian carcinoma appears to be a valuable alternative to traditional surgical staging.

Adult↗
PubMed1994

Central respiratory neuronal activity after axonal regeneration within blind-ended peripheral nerve grafts: time course of recovery and loss of functional neurons.

Autologous segments of peroneal nerve were implanted into the medulla of adult rats to induce axonal regeneration of central neurons axotomised during the grafting procedure. Grafts were inserted in the midline--where respiratory axons decussate--or laterally, either in the nucleus tractus solitarius or in the nucleus ambiguus, close to respiratory cell bodies. The distal part of each graft was left unconnected (blind-ended graft). Between 2 and 30 months post-implantation, unit recordings from single fibres were made from small strands teased from the grafts to investigate activity of neurons regenerating axons. Spontaneous respiratory and non-respiratory activity was present only in grafts examined between 2 and 6 months post-implantation. Respiratory units had discharge patterns identical to those of normal inspiratory or expiratory neurons; their responses to lung inflation and asphyxia were also similar to those of central respiratory neurons. No spontaneous activity was present in the grafts examined 7-30 months post-implantation. Moreover, asphyxia, which normally enhances the activity of central respiratory neurons, failed to elicit activity. These results were similar in all grafts, regardless of the site of implantation. The presence of spontaneous activity only between 2 and 6 months post-implantation indicates that once axonal growth of respiratory neurons is stopped within blind-ended grafts, those neurons still exhibited normal functional properties for 3 months. The absence of activity 6 months after grafting suggests that loss of functional regenerating respiratory neurons does not occur progressively and follows an "all or nothing" rule within blind-ended grafts.

Animals↗
PubMed1994

Atropine effects on the intermediate stage and paradoxical sleep in rats.

Paradoxical sleep (PS) in the rat, cat and mouse is preceded and sometimes followed by a short-lasting intermediate stage (IS) characterized by high amplitude cortical spindles and low frequency theta rhythm. This stage, which is mimicked by an intercollicular transection, is massively extended at the expense of PS by low doses of barbiturates. Since the pontine cholinergic cell activation of PS is suppressed by barbiturates, we studied whether atropine, an antimuscarinic compound, extends IS at the expense of PS. Atropine sulfate was given at 5, 10 and 20 mg/kg IP. All doses increased dose dependently the occurrence latency of IS and PS. The amount of IS and PS was decreased for several hours, principally by a decrease of the number of phases. At 20 mg/kg the phase mean duration of IS and PS was also decreased. Consequently, IS and PS are similarly supported by muscarinic processes. The theta rhythm frequency was scored during IS and outside PS phasic motor activities (type 2 theta). At all doses it was significantly increased for hours. The theta rhythm frequency was also transiently increased during the hypersynchronization periods of PS (type 1 theta). At 20 mg/kg it was similarly the case for type 1 theta rhythm during waking.

Animals↗
PubMed1994

Event-related potentials in humans as indices of access to stored information during sleep.

The even-related potentials are good indices of brain functions during sleep stages. The contingent negative variation (CNV), occurring in the interval between a conditional and a target stimulus, reflects information processing. The emitted potential which occurs when an expected stimulus is omitted reflects the access to a specific memory. During waking, deep slow wave sleep (stage 4) and paradoxical sleep seven subjects were submitted to a CNV paradigm, the target stimulus of which was occasionally omitted. The endogenous components of the evoked potentials induced at Fz, Cz and Pz locations by the auditory stimuli were analysed during the three behavioral stages. During stage 4 they were of largest amplitude and longest latency. These results are discussed in terms of neural excitability. CNV and emitted potentials were observed during waking and paradoxical sleep, but not during stage 4. These results suggest that information processing occurs during paradoxical sleep with access to waking memories during this stage of sleep, whereas information processing is absent during stage 4.

Adult↗
PubMed1993

Waking electroencephalograms in the blood-lymph and encephalitic stages of gambian trypanosomiasis.

Waking electroencephalograms (EEG) were recorded from 48 patients infected with Trypanosoma gambiense. The EEG of the 10 patients with blood-lymph involvement were indistinguishable from those of healthy controls but recordings from the 38 patients with the encephalitic phase of the disease showed three unusual profiles. One profile type, apparently indicative of early cerebral impairment, had a sustained low-voltage background similar to that seen during light sleep. A second profile type, seen in cases with acute cerebral involvement but without focal seizures, showed paroxystic waves. The third unusual EEG pattern was of various types of delta wave (similar to those seen in demyelinating encephalitis) and rapid, intermittent high-voltage delta bursts between periods of lower-voltage delta activity (as often seen in meningo-encephalitis); all types of delta wave were of higher voltage than the spike and wave complexes. Although no definite correlation has been established between the severity of the disease, the results of clinical tests, and waking EEG patterns, it appears that the three types of EEG profile are indicative of the degree of cerebral involvement.

Electroencephalography↗
PubMed1992

Central respiratory neurons of the adult rat regrow axons preferentially into peripheral nerve autografts implanted within ventral rather than within dorsal parts of the medulla oblongata.

A great number of severed central nervous system (CNS) neurons of the adult rat have the capillary to regrow axons into peripheral nerve autografts. In the present experiment, autologous segments of the peroneal nerve were inserted perpendicularly to the dorsal surface of the medulla oblongata more or less laterally within either the ventral respiratory group or the so-called dorsal respiratory group (ventrolateral grafts, n = 5; dorsolateral grafts, n = 5). From 2 to 4.5 months after the graft implantation, spontaneous unitary activities (n = 197) were recorded within all the grafted nerves: they were found to arise from both central respiratory (R, n = 60) and non-respiratory (NR, n = 137) neurons which were giving off regenerated axons along the nerve grafts. The graft reinnervation by respiratory axons was found to be significantly more abundant within the medullary ventrolateral grafts than within the dorsolateral ones. The low rate of axonal regeneration from respiratory neurons observed within the dorsolateral grafts provides further evidence that the number of the respiratory neurons in the dorsal respiratory group, if present at all, is much smaller than that of the ventral respiratory group in the rat.

Animals↗
PubMed1991

Axonal regeneration from central respiratory neurons of the adult rat into peripheral nerve autografts: effects of graft location within the medulla.

In adult rats, autologous segments of the peroneal nerve were implanted into the medulla oblongata at the level of the obex either on the midline (midline grafts, n = 4), where respiratory axons decussate, or on the left side (lateral grafts, n = 5) in the area of the respiratory cell bodies. Several months after the graft implantation, spontaneous unitary activities (n = 225) were recorded within the grafts and were found to arise from both central respiratory (R, n = 72) and non-respiratory (NR, n = 153) neurons which were giving off regenerated axons along the nerve grafts. The graft reinnervation by respiratory axons was found to be significantly more abundant within the medullary lateral grafts than within the midline grafts. This finding offers further support of the conclusion that the reinnervation of grafts by axons from central neurons is enhanced when the graft is placed proximally to the cell bodies.

Animals↗
PubMed1990

Functional significance of the dorsal respiratory group in adult and newborn rats: in vivo and in vitro studies.

The involvement of the dorsal part of the medulla (the so-called dorsal respiratory group: DRG) in the networks participating in respiratory function was investigated in newborn (in vitro) and adult (in vivo) rats. In the dorsal part of the medulla of the isolated brainstem of newborn rats, no respiratory neurons were found and stimulations or lesions neither modified nor suppressed the respiratory output. On the contrary, similar experiments suggest that sites in the ventral medulla have a fundamental importance for respiration. In adult rats, lesion of the DRG areas by electrocoagulation induced transient changes in respiratory timing, and resulted in a significant decrease in the amplitude of the contralateral phrenic output. These results suggest that the dorsal part of the medulla is not involved in controlling respiratory activity in the newborn rat. In adults, no definite conclusion can be reached, but the functional role of the DRG, if any, is probably restricted.

Action Potentials↗
PubMed1990

Effects of N-methyl-D-aspartate (NMDA) antagonist MK-801 on breathing pattern in rats.

In anaesthetized, bivagotomized and artificially ventilated rats, the respiratory effects of systemic injection of MK-801, a non-competitive N-methyl-D-aspartate antagonist, were studied. In all the experiments (n = 11), the injection increased the inspiratory duration and decreased the expiratory duration. In 4 experiments, the inspiratory duration was drastically lengthened, resulting in an apneustic-like breathing pattern. These results demonstrate that apneusis is difficult but possible to induce in rats and suggest that termination of inspiration is controlled via central mechanisms in which NMDA-like receptors are involved.

Action Potentials↗
PubMed1990

[Anatomo-radiologic approach of the mechanical pathology of the upper fibulo-tibial joint].

The authors report a study of 150 cadavers dissections. The morphology and topography of the proximal tibiofibular joint were analysed. The numerous anatomo-radiological variations encountered explain the different pathologies seen in clinical practice. The authors insist on the influence of this joint on ankle motion and recommend an association of a distal diaphyseal resection of the fibular when an arthrodesis of the proximal tibio-fibular joint is performed.

Autopsy↗
PubMed1989

Pneumotaxic centre and apneustic breathing: interspecies differences between rat and cat.

Pontine influences on the breathing pattern were studied in rats using either in vivo experiments in anaesthetized adult animals or in vitro experiments in newborn preparations. In cats, after anaesthesia and bivagotomy, pontine transection has been described as evoking an apneustic pattern of breathing (long sustained inspiratory discharges interrupted by short expiratory pauses). In rats, after anaesthesia, bivagotomy and pontine transection, apneustic patterns of breathing were not observed, either in vivo or in vitro. These results suggest interspecies differences between rat and cat in the pontine influences on the medullary respiratory generator.

Anesthesia, General↗
PubMed1989

Influence of instructions in multi-discrimination experiments on event related potentials.

The purpose of the experiment was to study the effects of psychological factors on slow brain potentials in relation to information processing and strategy establishment. Subjects were subjected to paired stimuli: A) two identical tone bursts (50 ms, 5000 Hz); B) two different stimuli the second (unconditioned) was a low pitched tone burst (50 ms, 500 Hz); C) only the warning stimulus was delivered to the subjects. In a first experiment, subjects (N = 10) were asked to detect and signal by a motor act the low pitched click (B); in a second experiment, subjects (N = 8) were to detect and signal in the same way the unconditioned tone burst omission (C). Results showed that the auditory event-related potentials (ERP) obtained in the two experiments presented two components: a negative wave (N150) followed by a positive one (P270). Solely, the late positive component differed in topography during the two situations. A fronto-central Contingent Negative Variation (CNV) appeared in all the conditions for the two experiments while a Post Imperative Negative Variation was often obvious in the first experiment.

Adult↗