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Biomedical subjects

P Gauthier

Publications and source records attributed to P Gauthier.

At least 37 records · Page 2Linked to original sources

Rapid ELISA D-dimer testing in the exclusion of venous thromboembolism in hospitalized patients.

The clinical diagnosis of deep-vein thrombosis (DVT) and pulmonary embolism (PE) is known to be unreliable. Until now, no biological marker has been found to confirm thrombosis, but help can be gained from a biological marker ruling out the diagnosis of DVT or PE, i.e., the sensitive measurement of D-dimer (DD) species. This article summarizes our experience in introducing a rapid D-dimer test (ELISA VIDAS D-dimères test, bioMérieux) in a collaborative strategy for thrombosis diagnosis during 9 consecutive months involving 1,131 measurements. The efficacy of the DD test was very different according the type of patient, and departments where the DD test provides a real diagnostic benefit were identified. High clinical probability for thrombosis was encountered in 32 patients and radiology was carried out, although D-dimer was negative: none of these patients was found to have a thrombosis after radiologic examination. However, extensive progress must be made in test prescription to reduce the excessive rate of positive D-dimer tests (78%) and positive measurements that are not followed up by radiology (42%).

Biomarkers↗

[Thoracic drainage in trauma emergencies].

A group of 191 cases of emergency tube thoracostomy for acute trauma reviewed retrospectively from March 1993 to March 1998 is reported. Of this group 169 were men and 22 were women. Their ages ranged from 16 to 73 years. The causes were as follows: 89 cases (46%) road accident; 33 cases (17%) accidental trauma; 33 cases (17%) someone else violence (assault, gunshot or stab wound); 15 cases (8%) work accident; 11 cases (6%) domestic accident and 5 cases (3%) iatrogenic trauma. In 32 patients a diagnosis of pneumothorax was made (2 tension, 11 for penetrating chest injuries, 19 after blunt trauma). In 2 cases of tension pneumothorax and in 3 cases of open pneumothorax a chest tube (24-28 Fr) in the third space in the mid-clavicular line was introduced. In the other patients it was decided to place a chest tube in the mid-axillary line in the fifth intercostal space to drain pneumothorax. Only in 7 cases suction was necessary. Fifty-four hemothorax (3 bilateral) were treated in 11 cases using thoracentesis, while the remaining cases were treated using the insertion of multiple drainage holes in the intercostal space (fifth in the mid-axillary line directed inferiorly and posteriorly). One hundred and three were the cases of hemopneumothorax: 24 of them received 2 chest tubes, the first (20-26 Fr) apically in the second intercostal space in the mid-clavicular line, the second (32-38 Fr) in the fifth intercostal space in the mid-axillary line. All the other cases were treated using a single thoracostomy. In 14 cases suction was applied. Two cases of chylothorax resolved by a large tube positioned in the chest (fifth intercostal space in the mid-axillary line) with a constant negative pressure were also observed. Duration of tube drainage ranged from 4 and 18 days, with an average of 11 days. Five infections of thoracostomy site and 1 empyema resolved by rethoracotomy were observed. Moreover, there were 3 complications: 2 subcutaneous placements and 1 little laceration of the lung. Thirty-one drained patients were operated: in 5 cases thoracotomy and laparotomy (2 exitus in tabula); only thoracotomy in 8 cases; 19 laparotomy and thoracostomy (1 exitus in tabula).

Accidents, Home↗

The intermediate stage and paradoxical sleep in the rat: influence of three generations of hypnotics.

Paradoxical sleep in the rat, cat and mouse is preceded and sometimes followed by a short-lasting intermediate stage characterized by high-amplitude anterior cortex spindles and low-frequency hippocampal theta rhythm. Several neurophysiological arguments suggest that the intermediate stage corresponds to a brief functional disconnection of the forebrain from the brainstem. This paper is devoted to the review of quantitative and qualitative influences of three generations of hypnotics on the intermediate stage-paradoxical sleep couple. Barbiturates, first-generation hypnotics, extend the intermediate stage at the expense of paradoxical sleep. Three benzodiazepines are compared, two with a short half-life (triazolam and midazolam) and one with a long half-life (diazepam). They also decrease sleep occurrence latency and increase the intermediate stage at the expense of paradoxical sleep, except for midazolam, which increases both the intermediate stage and paradoxical sleep at low dose. Zolpidem and zopiclone, hypnotics of third generation, decrease paradoxical sleep but the intermediate stage never substitutes for paradoxical sleep. The results are discussed in relationship to the functional aspects of this turning-point period of sleep.

Animals↗

D-dimer strategy in thrombosis exclusion--a gold standard study in 100 patients suspected of deep venous thrombosis or pulmonary embolism: 8 DD methods compared.

DD are now recognized as a valuable tool to screen patients suspected of deep venous thrombosis or pulmonary embolism before carrying out a gold standard radiologic examination. The newest methods available claim to be able to ascertain the absence of thrombosis, but they have yet to prove their efficiency. We compared the performances of 3 reference ELISA methods (D-DI Asserachrom Stago, D-dimer Enzygnost Behring and Dimertest GOLD EIA Agen), 5 recent rapid methods (VIDAS D-Dimer bioMérieux, Instant IA Stago, Simplired Agen, Nycocard D-dimer Nycomed and Accuclot D-Dimer Sigma Diagnostics) and two routine latex methods (Dimertest American Diagnostica and FDP-Slidex bioMérieux) in 100 patients. One of the rapid quantitative methods was demonstrated to have a level of efficiency comparable to that of ELISA methods. Finally, the cost and efficiency of different strategies were evaluated, the association of a routine latex method with the VIDAS D-Dimer bioMérieux being proven to be the most efficient.

Adult↗

Influence of a GABA(B) receptor antagonist on the sleep-waking cycle in the rat.

The influence of CGP 35348 (a GABA(B) receptor antagonist) on the sleep-waking cycle was studied in rats. The animals were injected i.p. at the beginning of the light period and the data expressed by 2-h periods and total duration (6 h). At 100 mg/kg, slow-wave sleep (SWS) was decreased during the 6-h recording with a peculiar decrease during the first 2 h. SWS was subdivided into three stages: slow-waves; spindles occurring as SWS deepens; and intermediate stage appearing prior to paradoxical sleep (PS). Only the slow-wave stage and intermediate stage were decreased. Waking was increased during the 6-h recording. It was subdivided into waking with hippocampal theta rhythm (psychomotor active waking) and waking without theta activity (quiet waking). Both were increased during the first 2 h. However, quiet waking was increased throughout the recording duration. At 300 mg/kg, SWS was decreased during the three 2-h periods. This decrease was principally related to a decrease of the slow-wave stage. PS was increased over the 6-h recording with a marked increase during the second 2-h period. Consequently, under the influence of the GABA(B) receptor antagonist, the SWS was decreased at the expense of behavioral stages with cortical low-voltage activity (waking and PS). GABAergic neurons are present in the mesopontine structures responsible for these two stages. We can conclude that endogenous GABA acting at the GABA(B) receptor level participates in the regulation of waking and PS.

Activity Cycles↗

CNS axonal regeneration with peripheral nerve grafts cryopreserved by vitrification: cytological and functional aspects.

To test cool-warm protocols for storing peripheral nerves, 4-cm-long-nerve segments were removed from the hindleg of adult rats and cryopreserved using a vitrification solution (or cryoprotective mixture) containing a mixture of polyalcohols (2,3-butanediol, 1,2-propanediol, polyethylene glycol, and Belzer U.W. medium). Schwann cell viability and morphology were studied with regard to the effect of (i) cryoprotective mixture concentration (100, 50, and 30% diluted in human serum albumin at 4%), (ii) duration of exposure (10, 15, or 30 min in a single step) of nerves to the cryoprotective mixture, (iii) cooling rate (F1/F2, F3, and F4: 3, 12, and 231 degrees C/min, respectively), and (iv) type of replacement of cryoprotectant (T1, one step; or T2, perfusion) after warming. Nerves exposed 10 min to cryoprotective mixture 50% (2,3-butanediol, 1.926 mol.liter-1; 1,2-propanediol, 3.063 mol.liter-1; polyethylene glycol, 0.084 mol.liter-1; and Belzer U.W., 22.4 mosm-1) and cooled-warmed with the F2/F3/F4-T2 protocols contained live and correctly cryopreserved Schwann cells. The capacity of these cryopreserved nerve segments (n = 6) to be subsequently repopulated by regenerating axons from central neurons was compared to that of fresh nerves when used as peripheral nerve autografts implanted within the spinal cord at the level of the descending respiratory pathways. All cryopreserved nerve grafts were successfully reinnervated by regenerated central axons. Unitary spontaneous action potentials propagated along these axons were assessed by recording the discharge of tested nervous filaments (T) from the grafts in artificially ventilated and paralyzed animals. Out of 535 T, 32 (6 +/- 1.2%) presented spontaneous unitary activity with respiratory (R, n = 2) and nonrespiratory (NR, n = 30) pattern of discharge. The T mean number, the occurrence rate referenced to the total number of T (R/T, NR/T, and R + NR/T) and the mean number of spontaneous units (R, NR, R + NR) were compared to those of fresh spinal peripheral nerve grafts. Except for T, cryopreserved peripheral nerve grafts contained statistically significantly (P < 0.05) less spontaneous R and NR unitary activity, which represented, respectively, 6.2 +/- 6.2 and 26.8 +/- 5.7% of that found in the control group. These data indicate that nerves cryopreserved with the protocols described above contain viable Schwann cells which constitute a suitable support to induce regeneration of central fibers. The effectiveness of nerve cryopreservation by vitrification is discussed with regard to Schwann cell viability following cool-warm protocols and to subsequent reinnervation of the cryopreserved peripheral nerve grafts.

Animals↗

Meta-analysis of the effectiveness of physical activity for the prevention of bone loss in postmenopausal women.

A meta-analysis was done to measure the effect of physical activity on the bone mass of healthy postmenopausal women. All studies published between 1966 and 1996, in French or English, were reviewed for inclusion from Medline search, bibliographies of relevant studies, review articles and books. Studies had to be prospective intervention trials, randomized or not, evaluating the effectiveness of an exercise program of any duration, frequency and intensity, with a control group. Studies had to measure bone parameters and involve healthy postmenopausal women over 50 years of age who were free of symptomatic osteoporosis at the time of study entry. Effect sizes (ES) were calculated for each bone parameter and site measured in every eligible study according to Hedges and Olkin. DerSimonian and Laird's model was used to estimate overall effect sizes when combining studies. All analyses were bone parameter and site specific. Of 217 papers extracted from the literature, 187 did not meet eligibility criteria and 12 others were rejected. The two main reasons for rejection were that both genders were combined in the analyses and no exercise group without drug interaction was present. Eighteen studies were included for meta-analysis. Taking into account the frequency, duration, compliance rate and average age of the subjects, the programs were judged of moderate intensity and focused on walking, running, physical conditioning and aerobics. A significant effect of physical activity was detected on the bone mineral density at the L2-4 level of the lumbar column in studies published after 1991 (ES = 0.8745, p < 0.05). No effect could be seen, however, on forearm and femoral bone mass. Although applied to a small number of studies, this meta-analysis suggests that exercise programs in a population of postmenopausal women over 50 years of age are effective for preventing spinal bone mineral density loss at the L2-4 level. However, such programs do not have any effect on the forearm or femoral bone mass.

Aged↗

Influence of zopiclone, a new generation hypnotic, on the intermediate stage and paradoxical sleep in the rat.

This study examined the influence of zopiclone, a third generation hypnotic, on the transition from slow wave sleep to paradoxical sleep (PS) which is increased at the expense of PS by barbiturates and benzodiazepines. The compound decreased sleep latency and increased the latency of the intermediate stage (IS) and PS at 2.5, 5 and 7.5 mg/kg IP. The amount of the IS was decreased because of the decrease in phase number up to 6 h at all doses. PS amount was decreased during 2 h at 2.5 mg/kg and during 4 h at 5 and 7.5 mg/kg also because of the decrease in phase number. The IS never substituted for PS. The IS spindle characteristics were not modified and the theta rhythm frequency slightly decreased at 5 mg/kg (IS) and 7.5 mg/kg (PS).

Animals↗

A weight-bearing, water-based exercise program for osteopenic women: its impact on bone, functional fitness, and well-being.

OBJECTIVE: To evaluate the effects of a weight-bearing, water-based, exercise program designed for women with low bone mass. DESIGN: A test-retest cross-sectional, prospective study. SETTING: Community-dwelling women from a Canadian city. PARTICIPANTS: Seventy-seven postmenopausal women, 50 to 70 years of age, with spinal or femoral bone density below the fracture threshold. INTERVENTION: Subjects exercised in a pool with waist-high water for 60 minutes, 3 days a week, over a 12-month period. Forty minutes of each session were devoted to successive jumps and muscular exercises designed to promote bone accretion, strength, and endurance. MAIN OUTCOME MEASURES: Spinal and femoral bone mineral density (BMD) measured by dual-energy X-ray absorptiometry, functional fitness (flexibility, coordination, agility, strength/endurance, and cardiorespiratory endurance) assessed with the American Alliance for Health, Physical Education, Recreation and Dance battery, and psychological states evaluated with Dupuy's General Well-Being Schedule. RESULTS: Spinal BMD decreased significantly (p < .001), whereas there was no change in femoral neck BMD (p = .90). Four of the parameters chosen to assess functional fitness, namely, flexibility, agility, strength/endurance, and cardiorespiratory endurance, were affected positively by the exercise program (all p values < .001). Psychological well-being also improved significantly after participation in the exercise program (p < .001). CONCLUSION: The intervention was successful in improving the functional fitness and psychological well-being of the participants, despite a lack of effect on the skeletal system. Future studies are needed to identify water exercises that are safe yet exert enough stress on the bones to initiate a bone response.

Aged↗

Dual staining assessment of Schwann cell viability within whole peripheral nerves using calcein-AM and ethidium homodimer.

A membrane permeant nucleic acid stain, ethidium homodimer was used in combination with calcein-AM to document the viability of Schwann cells (SCs) in whole nerves after cold storage assays. Segments of peripheral nerves were, (i) kept intact in buffer (viability controls), (ii) thawed after a cryopreservation, according to a protocol which has been previously shown to maintain the integrity of most nerve components [Ruwe and Trumble, J. Reconstr. Microsurg., 1990, 6: 239-244; Gauthier et al., In 3rd International Symposium on Axonal Regrowth in the Mammalian Spinal Cord and Peripheral Nerve, Deauville, France, 1995, p. 24, abstract], (iii) killed by chemical injury, or (iv) by successive freezing-thawing. Teased preparations of nerve fibers were prepared from the various types of nerve segments and incubated with calcein-AM and ethidium homodimer, which stain, respectively, living and dead cells. In control or cryopreserved nerves, staining with calcein-AM resulted in bright green fluorescence in the cytoplasm of SCs, with no red fluorescence of ethidium homodimer. In contrast, in killed nerve preparations, intense ethidium red fluorescence was observed in SC nuclei, with negligible green calcein cytoplasmic fluorescence. Thus, the combination of calcein-AM/ethidium homodimer appeared as an effective tool for assessing the viability of SCs and determine the quality of cold stored nerve preparations used in graft repair procedures. In addition, the generated fluorescence enabled clear visualization of myelinated fibers by confocal imaging.

Animals↗

[Regrowth of central respiratory pathways in neural graft. From research tool on the axonal regeneration to a strategy of post-traumatic reparation].

This review focuses on the regrowth of respiratory pathways after nerve grafting within the central nervous system of the adult rat. After a general presentation of the background and of the grafting procedure, we summarize our nerve grafting results of while it is now well established that severed axons of adult central neurons can regenerate within segments of peripheral nerve partially implanted within the brain or spinal cord, the functional properties of the regenerating neurons remain generally unknown. With a view to assessing the extent to which the functional capacities of central neurons can be maintained after axonal regeneration, we have carried out experiments on central respiratory neurons which are a good example of a highly organized neuronal network with characteristic patterns of spontaneous discharge. We have shown that axonal regrowth of central respiratory neurons was successfully induced in blind-ended medullary and spinal autografts implanted respectively within the respiratory centers of the medulla oblongata and within the cervical spinal cord at the level of descending respiratory pathways. The grafts consisted of true "supplementary nerve" in which normal afferent and efferent respiratory pathways were confirmed by recording respiratory unitary discharges from teased fibers within the grafts. The efferent discharges reflected the activity of central respiratory neurons that had regenerated axons within the grafts: these neurons manifested spontaneous activity and normal responsiveness to respiratory stimuli that resemble those of normal respiratory cells. In order to evaluate the possibility of experimental nerve banking, the feasibility of using short-term and long-term stored nerves as potential spinal nerve grafts was established using in vitro pre-degenerated nerve and cryopreserved nerve grafts after assessment of Schwann cell viability. The extent of respiratory reinnervation of the different grafts (medullary, spinal and stored nerve grafts) was compared. The discussion focuses on the main data and the strategy for future nerve grafting is evoked: functional characteristics of regenerating respiratory axons, extent of graft reinnervation, functional schwann cell survey within stored/grafted nerve and post-traumatic grafting.

Animals↗

In vitro pre-degenerated nerve autografts support CNS axonal regeneration.

In the present study we compared, in adult rats, the axonal regeneration of central respiratory neurons within autologous fresh (f-; grafted immediately after removal) and pre-degenerated (pd-; grafted after being stored during 3 days in saline at +8 degrees C) peripheral nerve grafts (PNGs) implanted within the C2 cervical spinal cord. The proximal end of the left peroneal nerve was implanted in the site of projection of medullary respiratory neurons (ventro-lateral quadrant) and the distal part of each nerve graft was left unconnected (blind-ended graft). PNGs were examined 2 to 4 months after grafting. Central neurons regenerating axons within the PNGs were studied by recording spontaneous unit activity from small strands teased from the grafts. In control f-PNGs (n = 9), 248 filaments had spontaneous activities, 58 of these were respiratory-related, i.e. had discharge patterns identical to those of normal respiratory (inspiratory and expiratory) neurons. The presence of regenerated nerve fibers with spontaneous unitary impulse traffic (n = 216) was found in all pd-PNGs (n = 5). Thirty-four had respiratory patterns identical to those found within f-PNGs and corresponded to efferent activity. No statistically significant differences in axonal regrowth were found between f- and pd-PNGs. In conclusion, f- and pd-PNGs were equally capable of promoting axonal regeneration of central neurons. The neural components (Schwann cells and others) required for axonal regeneration of adult central neurons are still effective following 3 days of in vitro peripheral nerve degeneration without special storage conditions (oxygenation, medium inducing ATP synthesis). These results have clinical implications for nerve graft surgery when time is required for typing the tissues of both donor and recipient (post-mortem allografts) or transportation of graft material.

Animals↗

Regeneration of respiratory pathways within spinal peripheral nerve grafts.

Central respiratory neurons exhibit normal activity after axonal regeneration within blind-ended peripheral nerve grafts (PNGs) inserted near the corresponding cell bodies in the medullary respiratory centers. Part of these medullary respiratory neurons project toward the spinal cord and contribute to descending respiratory pathways that control respiratory motoneurons. The present work investigates to what extent cervical respiratory pathways could be directed out of the central nervous system within PNGs inserted distant to the medullary respiratory nuclei. In adult rats (n = 13), autologous segments of the peroneal nerve were implanted into the ventrolateral part of the C2 spinal cord at the level of the descending respiratory pathways. Two to four months after grafting, electrophysiological recording of teased graft filaments (n = 562) revealed the presence of regenerated nerve fibers with unitary impulse traffic (n = 164) in all tested PNGs (n = 6). Respiratory discharges (n = 52) corresponded to efferent and afferent activity. Efferent respiratory discharges (n = 32) originated from central respiratory neurons which remained functional and preserved afferent connections. Retrograde horseradish peroxidase labeling applied to the distal cut end of PNGs (n = 7) revealed stained (42/1997) neurons in areas where respiratory cells have been described. Afferent respiratory discharges (n = 20) were synchronized with lung inflation but their origin (stretch pulmonary receptors and/or respiratory muscle receptors) was not determined. On the basis of additional data from light and electron microscopy of PNGs, comparison was made between anatomical, retrograde labeling, and electrophysiological data. The main conclusion is that spinal PNGs appear to be able to promote axonal regeneration of functional respiratory efferent and afferent pathways.

Animals↗

Influence of paradoxical sleep deprivation on the intermediate stage of sleep in the rat.

In the rat, paradoxical sleep (PS) is preceded by a short-lasting stage characterized by high amplitude cortical spindles and low frequency hippocampal theta rhythm. This intermediate stage (IS) is massively extended at the expense of PS by barbiturates and benzodiazepines. To further study the relationship between the IS and PS, six rats were PS deprived for 48 h by sitting on one of three small platforms surrounded by water. A control group of six other rats remained in dry cages with shavings. After 24 h PS deprivation the latency of IS occurrence increased, was unchanged after 48 h deprivation and decreased during recovery on shavings after 52 h deprivation. The total IS duration, number of episodes and mean duration per episode were unchanged during deprivation but increased during recovery. This recovery was characterized by an increase in the number of PS episodes and the total duration while the latency of PS occurrence decreased. The frequency of theta rhythm, unchanged for PS, increased for the IS during deprivation and recovery. In conclusion, the IS did not substitute for PS after selective deprivation.

Animals↗

Impact of a 12-month exercise program on the physical and psychological health of osteopenic women.

OBJECTIVE: To describe the effect of a supervised physical activity program on the physical and psychological health of osteopenic women. DESIGN: A randomized controlled trial. SETTING: Sherbrooke, Quebec, Canada. PARTICIPANTS: A total of 124 community-living postmenopausal women, between 50 and 70 years of age, with low bone mass took part in the study. INTERVENTION: Subjects allocated to the experimental group performed weight-bearing exercises (walking, stepping up and down from benches), aerobic dancing, and flexibility exercises for 60 minutes, three times a week, over a period of 12 months. All subjects were invited to attend bi-monthly educational seminars covering topics related to osteoporosis. OUTCOME MEASURES: Spinal and femoral bone mineral density (BMD), functional fitness (flexibility, coordination, agility, strength/endurance, cardiorespiratory endurance), psychological well-being, back pain intensity, and self-perceived health. RESULTS: Spinal BMD stabilized in the exercisers while decreasing significantly in the controls (P = .031). No change in femoral BMD was observed in either group (P = .597). Four of the five parameters chosen to evaluate functional fitness, namely flexibility, agility, strength, and endurance, were affected positively by the exercise program (all P < .01). Adjusting for prescores by means of an analysis of covariance revealed a significant difference between the groups in psychological well-being, which favored the exercisers (P = .012). After 12 months, back pain reported by exercisers was lower than that reported by controls (P = .008). Finally, self-perceived health increased in the exercise group, whereas no difference was observed in the control group (P = .790). CONCLUSION: These results suggest that after 12 months, exercising can produce a significant increase above initial levels in the functional fitness, well-being, and self-perceived health of osteopenic women. Intensity of back pain can also be lowered by exercise. The exercise program succeeded in stabilizing spinal BMD but had no effect on femoral BMD.

Aged↗

[Nerve transplantation in the central nervous system: a strategy for inducing nerve fiber regeneration in lesions of the brain and spinal cord].

Nerve grafts have long been used as a reconstructive strategy in the human peripheral nervous system. In the nervous system (brain and spinal cord), peripheral nerve grafts have been used experimentally for promoting axonal regeneration in lesioned pathways. Peripheral nerve grafts play the role of physical and trophic supports that are favourable for the regeneration of central fibres that normally present only abortive regeneration in adult mammals. On the basis of several experimental models (axonal regeneration of retinal ganglion cells, respiratory neurones, ...) it has now been established that central fibres that have regenerated within the nerve grafts retain their ability to transmit normal nervous information and can make functional synaptic contact with a target. If such a strategy is not yet used in man, it nevertheless constitutes a promising approach for the investigation of the central nervous system plasticity, and could be useful in the treatment of spinal cord injuries.

Adult↗

[Use of compression anastomosis devices in digestive surgery].

In this summary the authors report their experience of the clinical utilization in digestive surgery of a new compression anastomosis device consisting of a biofragmentable ring (BAR-Valtrac). From January 1993 through August 1994 26 patients underwent operations with Valtrac application: 22 for malignant colo-rectal neoplasms, 3 for diverticular disease and 1 for Crohn disease. The authors have performed 8 ileo-colic, 16 colo-colic and 2 colo-rectal anastomoses. There was no perioperatively mortality. Valtrac was discharged post-operatively between XVI and XXVIII days. There were no anastomotic leakage, bleeding or obstruction. Six months postoperatively an endoscopic control carried out in the 50% of the patients showed no anastomotic stenoses. These results, in association with those ones reported by the literature, confirm that anastomoses performed with Valtrac are safe, reliable and allow the same of better results than stapled anastomoses.

Adult↗