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Biomedical subjects

M Lacour

Publications and source records attributed to M Lacour.

108 records · Page 6Linked to original sources
PubMedDate not supplied

The orthopaedic presentation and management of Sjögren-Larsson syndrome.

Sjögren-Larsson syndrome is a rare autosomal recessive neurocutaneous disorder in which the combination of spasticity, ichthyosis, and mental retardation commonly result in patients being wheelchair bound. We reviewed a cohort of children with Sjögren-Larsson syndrome who were successfully managed with early physiotherapy and later soft-tissue surgery. The favourable outcome seen in these patients should encourage orthopaedic intervention in suitable cases.

Child↗
PubMedDate not supplied

[Contraindications to the use of extraoral forces in dentofacial orthopedics].

Following a brief and non-exhaustive review of the various types of extra-oral traction, the author stresses certain contra-indications which, in his opinion, should be borne in mind by the operator. These contraindications, are, essentially, a pathological mesiodistal orientation of the adult molars, reflecting dento-maxillary disharmony in the anterior segments, and an abnormality of inclination of the alveolar processes for which aetiological treatment is more rational.

Adult↗
PubMedDate not supplied

[Compensation deficits in posture and kinetics following unilateral vestibular neurectomy in cats. The role of sensorimotor activity].

The role of sensorimotor activity in compensating deficits following unilateral vestibular neurectomy was studied in four adult cats using behavioral tests. Disturbances in posture and equilibrium were quantified and their subsequent compensation was described in both sensorimotor restrained and unrestrained cats. Sensorimotor restriction (S.M.R.) lasted 7 days and was performed in different postoperative periods. In the unrestrained animal, postural asymmetry compensation followed a 3-phase time course leading to preoperative criteria after about 40 days. Recovery of equilibrium developed by steps and was achieved after about 50 postoperative days. A first week applied S.M.R. was most effective in stopping postural symmetry recovery, while a later S.M.R. had no effect on the recovery time course and did not produce decompensation. On the contrary, S.M.R. (1st week or 3rd week) prevented and delayed equilibrium recovery, the earlier S.M.R. producing maximal effects. These observations suggest a CNS "sensitive period" to vicariant inputs.

Animals↗
PubMedDate not supplied

Pharmacological activity of the Ginkgo biloba extract (EGb 761) on equilibrium function recovery in the unilateral vestibular neurectomized cat.

Locomotor balance recovery after unilateral vestibular neurectomy has been found strongly accelerated in the cat when the animals received a postoperative treatment with Ginkgo biloba Extract (EGb 761:50 mg/kg/d, i.p.), a result due to the improvement of plasticity mechanisms involved in vestibular compensation. The aim of this study was to determine which of the two main biochemical components (terpenes vs. flavonoids) contained in the extract was the most active in the recovery process, to test the influence of the route of administration, and to look for dose-dependent effects. Experiments were performed in six experimental groups of cats that were compared with each other and with three control groups. Comparisons were done on the recovery profile and time course of equilibrium function restoration, as quantified by the rotating beam test. Four experimental groups were treated with the standardized extract EGb 761 given orally (p.o.:2 groups; 40 mg and 80 mg/kg) or intraperitoneally (i.p.: 2 groups; 50 mg and 25 mg/kg), whereas the two others received only a special extract that did not contain the terpenes (i.p. administration: 25 mg and 10 mg/kg). Treatment was always given until complete recovery of locomotor balance function. The control groups received either no treatment (untreated cats), an oral vehicle (placebo cats), or a sham i.p. injection (sham cats). Results showed that locomotor balance recovery was significantly improved in all the experimental groups as compared to the control groups of cats, which recovered similarly and more slowly. Efficacy of the special extract without the terpenes was comparable to that of the total extract, indicating that the nonterpenic fraction was the most active biochemical constituent in this experimental model of central nervous system (CNS) plasticity. Pharmacological activity of the extract was also significantly better when given i.p. as compared to the p.o. route of administration, and dose-dependent effects were evidenced with the i.p. administration of the special extract without the terpenes, with a lower efficacy for the lowest dose (10 mg/kg). These data confirm that EGb 761 treatment serves as useful therapy in supporting brain functional recovery in this animal model of vestibular compensation and lead to a more precise understanding of the biochemical component that is active in this recovery process.

Administration, Oral↗
PubMedDate not supplied

Betahistine dihydrochloride treatment facilitates vestibular compensation in the cat.

Unilateral lesion of the vestibular system induces posturo-locomotor deficits that are compensated for with time. Drug therapy is currently used to improve the recovery process and to facilitate vestibular compensation. Betahistine dihydrochloride is an histamine-like substance that has been employed in vestibular pathology; it was found effective in many forms of vertigo and in vestibular-related syndromes. Investigations performed in animal models have shown betahistine-induced neuronal modulations in the vestibular nuclei complex and interactions with the H1 and H3 histamine receptors. Potentially, this substance is therefore capable to interfere with some recovery mechanisms and to improve the behavioral adaptations. But there is at present a total lack of data concerning the influence of betahistine treatment on vestibular compensation in animal models. The aim of this study was to understand the pharmacological activity of betahistine in the restoration of posture and locomotor balance functions in unilateral vestibular neurectomized cats. Posture recovery was assessed by quantifying the surface reaction of the cat's support as measured while standing erect on its four legs, at rest. Locomotor balance recovery was determined using the rotating beam test, by measuring the maximal performance (max. P.) of the cat and its locomotion speed regulation during the postoperative time period. We have compared the recovery profile and time course of these static (posture) and dynamic (equilibrium) functions in three groups of cats. Two experimental groups were treated at daily doses of 50 mg/kg and 100 mg/kg, respectively. Betahistine dihydrochloride was given orally until complete recovery of posturolocomotor functions. One untreated control group served as the reference. Results showed that postoperative treatment strongly accelerated the recovery process in both treated groups, inducing a time benefit of around 2 weeks as compared to the controls. Maximum performance of the cats on the rotating beam as well as locomotion speed regulation were highly correlated to the postoperative development of the cat's support surface, indicating that compensation of the static vestibulospinal deficits conditioned the subsequent locomotor balance recovery. These behavioral data showed that betahistine dihydrochloride constitutes a useful drug therapy for the symptomatic treatment of central vestibular disorders in our animal model of unilateral vestibular lesion. Improvement of vestibular compensation under betahistine postoperative treatment, as evidenced here for the posture and locomotor balance functions, is discussed both in terms of aspecific effect (histamine-induced increase of the level of vigilance) or more direct action in the vestibular nuclei (histamine-induced rebalance of neuronal activity on both sides).

Administration, Oral↗
PubMedDate not supplied

Kinematic analysis of locomotion in unilateral vestibular neurectomized cats.

The vestibular syndrome following unilateral lesion of the vestibular system and the subsequent behavioral compensation over time have been well documented in many species. However, the locomotor pattern changes and the behavioral strategies used to preserve balance have still not been described. This study was aimed at quantitatively describing posturolocomotor behavior in cats tested before and after unilateral vestibular neurectomy (UVN) by the rotating beam test, which provides locomotor tasks of various difficulty. The position of head, neck, and trunk and the trajectory of the forelimbs and hindlimbs were recorded in 5 cats by 3D motion analysis. Step length and frequency walking velocity, and body height were computed. Results showed that normal cats adapted their locomotor patterns to the speed of beam rotation by increasing step length and/or frequency, that is, by increasing walking velocity, but without drastically changing their body posture. By contrast, UVN cats typically lowered their body centers of gravity and modified their locomotor patterns according to the locomotor task. Mean walking velocity was decreased in the low range of beam rotation as a result of smaller step length and lower frequency, and it was increased in the high range by opposite effects on these step cycle parameters. Modifications of the locomotor parameters were a function of the direction of beam rotation, showing significant reduction of step length, frequency, and velocity in the low range of counterclockwise compared to clockwise beam rotation, that is, during rotations toward the lesioned side. Phase plane plots of foot linear velocity with respect to foot linear displacement along the horizontal longitudinal axis displayed two different limit cycles, adapted to easy (low range of beam rotation) and more difficult (high range of rotation) walking conditions, in the normal cat. These dynamic profiles of the trajectories of the limbs during the step cycle were not greatly modified after vestibular lesion, but the phase plane typically observed in the high range for the normals was also found in the low range for the UVN cats. Thus, locomotor equilibrium function in the cat is strongly impaired following UVN, but locomotor balance can still be achieved in the UVN cats by the development of adaptive posturolocomotor strategies compensating for the lack of vestibular inputs.

Animals↗