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Biomedical subjects

L Tremblay

Publications and source records attributed to L Tremblay.

88 records · Page 5Linked to original sources
PubMed1982

Postnatal maturation of the ipsilateral optic tract in pigmented and albino mice.

After unilateral enucleation, degenerating axons in the ipsilateral optic tract of conventionally reared and dark-reared albino and pigmented mice were revealed by Fink-Heimer staining. The total number and the spatial distribution within the optic tract of these axons was found to be influenced by both pigmentation and by visual deprivation. The results are discussed in terms of delayed maturation of the optic tract contingent upon visual deprivation or anomalous ocular pigmentation.

Age Factors↗
PubMed1980

[The concept of autonomy (synthetic and operation indicators of old age : a systemic approach).].

The present study is a follow-up of a research project made in 1978 by the Equipe de Recherche Opérationnelle en Santé (EROS) of the Department of Health Administration at the Université de Montréal. The aims were a) firstly to construct a classification instrument by type for long-term care patients, enabling us, to identify these beneficiaries' needs, as well as to guide their placement in a health services' system. And b) to evaluate this instrument (realibility and validity), c) to initiate its implementation and d) to utilize it for evaluating the present placement system. This study constitutes the first stage in an approach aimed at producing, on the basis of a systematic scanning of data collected within the framework of the above-mentioned project; a comprehensive descriptive analysis of the social/health characteristics of an aged population (65 years and over) in one of Quebec's social/ health regions i.e. Montreal's South Shore. At first, the authors define the context and the objectives of the study undertaken; secondly, they define the concept of autonomy by showing how the latter is expressed concretely according to the observation instrument (evaluation form of the individual's functional autonomy). Thirdly, a presentation is made of the method of measurement, as well as certain results concerning an index of restricted autonomy directly released to situations of observable behaviour (e, g. daily-life activities, exploring the outside world, and housekeeping).

English Abstract↗
PubMed1979

DNA base composition, nature of intracellular DNA, morphology, and classification of bacteriophages infecting Micrococcus luteus.

Ten bacteriophages infecting Micrococcus luteus have been characterized. All phages contain double-stranded DNA, of 64.3--73.5 mol% guanine plus cytosine (GC). The DNA of phage N7 has the highest GC content reported for any bacterial virus. No unusual bases have been found. The intracellular replicating DNAs of six phages are covalently closed circular molecules. All 10 phages have isometric, probably icosahedral, heads and long, flexible, noncontractile tails and can be sorted into two morphological groups based on size and presence or absence of a collar. Host-range studies indicate six host-range groups.

Bacteriophages↗
PubMed1975

Prognostic value of nerve excitability test in Bell's palsy.

This paper reports the experience of the authors using facial nerve excitability test in Bell's palsy as a tool to understand better the prognosis in that pathology. The authors made a retrospective study of 222 cases of Bell's palsy, followed by serial facial nerve excitability test. The goal of this study as to define correlations between facial nerve excitability test (N.E.T.) values, the rate and degree of recovery OF PATIENTS PRESENTING A Bell's palsy. Results indicated that incomplete paralysis with a normal N.E.T. forecasts a fast and complete recovery in less than three months. Complete paralysis with a normal N.E.T. also forecasts a complete recovery. Those cases of complete paralysis with an abnormally elevated (greater than 2 m. amp.) N.E.T. lead to unsatisfactory results in 27.7 per cent of patients and of these 66.6 per cent took more than three months to recover if at all. Of the patients with complete paralysis and no response to facial nerve stimulation, 73 per cent showed an unsatisfactory recovery.

Adolescent↗
PubMedDate not supplied

Reward prediction in primate basal ganglia and frontal cortex.

Reward information is processed in a limited number of brain structures, including fronto-basal ganglia systems. Dopamine neurons respond phasically to primary rewards and reward-predicting stimuli depending on reward unpredictability but without discriminating between rewards. These responses reflect 'errors' in the prediction of rewards in correspondence to learning theories and thus may constitute teaching signals for appetitive learning. Neurons in the striatum (caudate, putamen, ventral striatum) code reward predictions in a different manner. They are activated during several seconds when animals expect predicted rewards. During learning, these activations occur initially in rewarded and unrewarded trials and become subsequently restricted to rewarded trials. This occurs in parallel with the adaptation of reward expectations by the animals, as inferred from their behavioral reactions. Neurons in orbitofrontal cortex respond differentially to stimuli predicting different liquid rewards, without coding spatial or visual features. Thus, different structures process reward information processed in different ways. Whereas dopamine neurons emit a reward teaching signal without indicating the specific reward, striatal neurons adapt expectation activity to new reward situations, and orbitofrontal neurons process the specific nature of rewards. These reward signals need to cooperate in order for reward information to be used for learning and maintaining approach behavior.

Animals↗
PubMedDate not supplied

Toe-to-thumb transplantation.

Microsurgical techniques have become useful in reconstructive surgery of the hand. Toe-to-thumb transplantation currently is the procedure of choice for thumb loss reconstruction. For a successful outcome, meticulous planning is imperative and presumes a thorough knowledge of the pertinent anatomy and surgical technique. The method of thumb reconstruction must be individualized and is dependent on the patient's functional needs, age, and the level of thumb amputation. Postoperatively, diligent nursing care is essential in assuring a positive outcome. Continuous communication between physicians and nurses is crucial. Astute monitoring and assessment are the core components of successful care.

Amputation, Traumatic↗
PubMedDate not supplied

[Dynamic focusing of informational convergence in basal ganglia].

Data in the literature support two apparently contradictory hypotheses: that of parallel processing and that of informational convergence in the basal ganglia. We present electrophysiological data supporting one and the other. Thus, at the output of the basal ganglia, in the intact monkey, neurons of the pallidum respond almost exclusively and in small number to passive limb movement. The specificity of the responses supports the parallel processing hypothesis. However, when the monkey is rendered parkinsonian by the neurotoxin MPTP, the dopaminergic deficit discloses a strong convergence upon pallidal neurons of information originating from different body parts. Such a convergence is also observed in the case of pallidal responses to electrical stimulation of the striatum. According to data in the recent literature, it is more likely that this information converges into the pallidum through the subthalamo-pallidal rather than the striato-pallidal pathway. On the other hand, pallidal responses to electrical stimulation of the striatum display a topological antagonistic center-surround organization, probably resulting from lateral inhibition. Moreover, changes in neuronal activities induced in the external pallidal segment by local injection of bicuculline display a similar organization and suggest the occurrence of a wide and powerful lateral inhibition in this pallidal segment. Such focusing mechanisms would be useless in an exclusively parallel system. One may therefore think that, in the normal individual, the level of dopamine dynamically focuses the system on the appropriate information. This would allow parallel processing in neuronal channels that are only relatively independent, since they can also demonstrate informational convergence.

Animals↗