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R Labrecque

Publications and source records attributed to R Labrecque.

At least 19 recordsLinked to original sources
PubMed1997

RNA-dependent phosphorylation of a nuclear RNA binding protein.

The human C1 heterogeneous nuclear ribonucleoprotein particle protein (hnRNP protein) undergoes a cycle of phosphorylation-dephosphorylation in HeLa cell nuclear extracts that modulates the binding of this protein to pre-mRNA. We now report that hyperphosphorylation of the C1 hnRNP protein is mediated by a kinase activity in nuclear extracts that is RNA-dependent. Although the basal phosphorylation of the C1 hnRNP protein in nuclear extracts reflects a casein kinase II-type activity, its RNA-dependent hyperphosphorylation appears to be mediated by a different kinase. This is indicated by the unresponsiveness of the RNA-stimulated hyperphosphorylation to casein kinase II inhibitors, and the distinct glycerol gradient sedimentation profiles of the basal versus RNA-stimulated C1 hnRNP protein phosphorylation activities from nuclear extracts. RNA-dependent phosphorylation was observed both for a histidine-tagged recombinant human C1 hnRNP protein added to nuclear extracts and also for the endogenous C1 hnRNP protein. Additional results rule out protein kinase A, protein kinase C, calmodulin-dependent protein kinase II, and double-stranded RNA-activated protein kinase as the enzymes responsible for the RNA-dependent hyperphosphorylation of the C1 hnRNP protein. These results reveal the existence in nuclear extracts of an RNA-dependent protein kinase activity that hyperphosphorylates a known pre-mRNA binding protein, and define an additional element to be integrated into the current picture of how nuclear proteins are regulated by phosphorylation.

Casein Kinase II↗
PubMed1997

Effect of focus lateralization on memory assessment during the intracarotid amobarbital procedure.

Despite the use of stimuli that can be processed by both hemispheres, a number of studies have reported lower memory scores after the left intracarotid amobarbital procedure (IAP) than after the right IAP. Because of that, failure after ipsilateral IAP is observed more often in patients with a left temporal seizure focus (LT) than in right temporal patients (RT), possibly needlessly excluding some LT patients from surgery. In order to overcome the deleterious effects of anesthetizing the dominant hemisphere, we designed an IAP protocol that did not promote verbal encoding of the stimuli. For this purpose, a large number of visual and tactile stimuli (colored pictures and real objects) were presented to be recognized later. The effect of seizure focus lateralization was examined in 82 temporal lobe epileptic patients who underwent IAP as part of their presurgical evaluation. As expected, for both RT and LT patients, long-term recognition of pictures presented under the effect of amobarbital was highly sensitive to the presence of a contralateral epileptic focus. However, contrary to what is generally reported, LT patients performed better than RT patients when their left (ipsilateral) hemisphere was anesthetized. In RT patients, although memory scores were lower after the left contralateral injection, the disparity in memory scores between the right and left injection was not as marked as in LT patients. These results are discussed in terms of the influence of type of processing required during the initial encoding on later recognition during IAP.

Amobarbital↗
PubMed1997

Visual agnosia with bilateral temporo-occipital brain lesions in a child with autistic disorder: a case study.

A 2-year-old boy meeting the criteria for autistic disorder was diagnosed 2 years later with a visual agnosia characterised by a combination of certain aspects of associative and apperceptive agnosia. MRI then revealed a severe encephalomalacia of the right temporal lobe and bilateral temporo-occipital areas. This association is discussed in terms of a clinical and aetiological relation between autistic disorder and visual agnosia.

Agnosia↗
PubMed1996

Multiple subpial transection: report of 7 cases.

7 cases of pure multiple subpial transection (MST) without associated cortical resection, for treatment of pharmaco-resistant partial epilepsy localized in highly functional cortical area, are reported. The transections were performed following the technique described by Morrell. The follow-up period ranged from 1 to 4 years. MST induced no significant neurological handicap: only 2 patients experiencing a transitory sensory-motor deficit and with total recovery within 1 month. With respect to seizures, 5 patients were improved with a decrease in seizure frequency of 100, 95, 75, 60 and 40%, respectively. Complex partial seizures changed postoperatively into simple partial seizures in 1 case. In conclusion, this procedure seems to be adequate, although no statistically significant results are available at this time. In our series, we believe failures could be attributed to either a very restricted area of transection or to an incorrect delimitation of the epileptic focus.

Adult↗
PubMed1996

To be or not to be at home? A neuropsychological approach to delusion for place.

A woman, LB, while in recovery from a viral encephalitis, exhibited a delusion for place, which led her to insist that she was at home, in spite of compelling evidence to the contrary. Later, she developed a Capgras syndrome, that is, another misidentification syndrome. The patient was given a detailed neuropsychological evaluation to shed light on the mechanisms underlying her delusional misbelief. Two main deficits were in evidence: (1) a severe visual-spatial impairment, giving the patient a distorted perception of her surroundings; and (2) frontal lobe dysfunction, which played a critical role in her impulsive responses and lack of self-awareness. The pathogenesis of delusion for place and persons if discussed in light of these observations.

Awareness↗
PubMed1996

[The man with 6 arms. An analysis of supernumerary phantom limbs after right hemisphere stroke].

Consequently an infarct in the territory of the right middle cerebral artery, a 77-year old man had a complete left sensory motor hemiplegia, with left neglect. For several weeks, he described the existence of one and more supernumerary phantom limbs. The patient's adamant and delusional conviction of their reality caused him considerable distress. Without being anosognosic he was not completely aware of his disorder, and had slight difficulties in judging what was plausible. The mechanisms underlying this delusion concerning specific parts of the body probably involve multifactorial disorders: first, a sensory deafferentation source of a distorsion of the perceived body schema; second, a resulting discrepancy between the perception of the body schema and its innate representation; third abnormalities of self-awareness and of self-judgement, leading the patient to argue forcellully in favor of incongruous rationalizations.

Aged↗
PubMed1994

Functional dissociations following bilateral lesions of auditory cortex.

We present two patients with bilateral lesions of the superior temporal cortex who manifested a number of functional dissociations in the auditory domain. The perception of speech and environmental sounds were preserved; yet, the perception of tunes, prosody and voice was impaired. As the processing of melodic but not rhythmic variations in musical sequences was selectively disturbed, the deficit cannot be attributed to a general impairment in auditory memory or sequential processing. These findings suggest that melody processing is not mediated by a general-purpose auditory architecture but by specialized cortical subsystems residing within the lesioned areas. Current taxonomies of auditory agnosia and models of normal music cognition are evaluated in light of the functional dissociations manifested by these patients.

Adult↗
PubMed1994

Autosomal dominant arteriopathic leuko-encephalopathy and Alzheimer's disease.

A 49-year-old man suffered from progressive dementia and seizures leading to death after 2 years. CT scans showed severe cortical-subcortical atrophy and hypodensity of the white matter. His father had died at about the same age with similar clinical signs. Two sisters and one brother were also affected. Neuropathological study revealed predominant involvement of the cerebral white matter with myelin loss, gliosis and type I lacunes. The small arteries and arterioles of the white matter and basal ganglia, and, to a lesser extent those of the subarachnoidal space, displayed fibrosis and replacement of the media by an eosinophilic, PAS positive, Congo Red negative, granular substance. Electron microscopy showed swollen myocytes surrounded by collagen, elastin and a compact electron-dense material. Immunofluorescence using antibodies against IgA, IgG, IgM, C1q and C3 stained the abnormal media weakly. In the cortex, there were diffuse senile plaques and neurofibrillary tangles. Immunohistochemistry demonstrated beta/A4 positive material in cortical senile plaques but not in arterial walls. Adventitial macrophages were, however, immunoreactive for gamma-trace. Systemic arterioles were normal. The vascular changes and leukoencephalopathy are comparable to those described in 'Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy' (CADASIL). Similar vascular changes were also observed in nonfamilial cases. An association with Alzheimer changes in the cortex has not been described previously. The relationship between both diseases and the role of each in the causation of the dementia is unclear.

Alzheimer Disease↗
PubMed1992

[Research and surgical treatment of epilepsy].

The currently available surgical procedures for the treatment of epilepsy, from fundamental data to therapeutic results, including various means of investigation are reported. The work is based on a review of the literature and on the cases studied by the two teams from the Universities of Montreal and Bordeaux who share the same concept of epilepsy surgery. The patient groups of the two teams include 316 S.E.E.G., 214 cortectomies, 39 callosotomies and 2 multiple sub-pial transsections. In the first part, the authors attempt to demonstrate that the epileptic focus corresponds to the region where the seizures arise, that this focus is not directly comparable to the region where inter-ictal spikes are recorded and sometimes becomes autonomous from the causal lesion. The epileptic phenomenon has a definite harmful effect on cerebral functions and a probable self-aggravating potential. The second chapter summarizes the clinical data on which the indications and contraindications are based. These obviously depend on whether the intervention is intended to be curative or palliative. Various non-invasive and invasive investigations are then reviewed, according to their relative importance and the experience of each team. The main points developed are: the electroclinical correlations during seizures, the symptomatological data for differentiating between temporal and frontal lobe seizures, the contribution of M.R.I. in demonstrating the epileptogenic and epileptic lesions, the electrophysiological information suggesting that S.E.E.G. remains the most informative mean of investigation. The various methods of investigation of assessing electrical, functional (cerebral blood flow, metabolism) and morphological aspects of epilepsy, supply non-redondant findings about the localisation of the epileptic focus. The chapter on surgical techniques mainly discusses the various modes of implantation of subdural and intracerebral electrodes and reports the same rate of morbidity in both cases. Orthogonal teleradiography is still perfectly suited to the implantation of intracerebral electrodes. S.E.E.G. is still the most anatomically precise technique. However, in certain conditions, extraoperative E.Co.G. is more adequate. New surgical modalities have recently appeared such as the multiple subpial transsections which allow treatment of epileptic foci unapproachable by cortectomy and such as modified techniques of hemispherectomy, which by decreasing morbidity, renew interest in them. In the chapter on surgical results, the authors emphasize the methodological problems of evaluation that partly account for their wide variability. The results obtained with the various surgical modalities are reviewed. The outcome in cortectomies is discussed at length in terms of the data from the literature as well as the results reported by both teams.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1990

Painful shoulder in the hemiplegic and unilateral neglect.

Shoulder pain is a frequent and debilitating problem in hemiplegic patients, and its etiology remains poorly understood. The role played by hemineglect in the appearance of shoulder pain was studied. During two years, 94 hemiplegic subjects were involved in a rehabilitation program after cerebrovascular accidents. Their average age was 68 years; 45 (47.9%) subjects had shoulder pain, and 24 subjects (22.5%) had hemineglect. The subjects with shoulder pain were compared to those without pain (the control group) with respect to gender, age, diabetes, heart failure, cardiac ischemia, scapulohumeral arthritis, and calcified tendinitis of the rotator cuff. We were unable to demonstrate a relationship between hemineglect and shoulder pain in the hemiplegic (X2 (1) = 2.03, p = .15), although pain was significantly more frequent in subjects with right hemispheric cerebrovascular accident (X2 (1) = 5.0, p less than .025). The subjects with shoulder pain had significantly more spasticity of the affected limb (X2 (1) = 26.3, p less than .01), less sensitivity to pinprick of the upper paralyzed extremity (X2 (1) = 10.8, p less than .01), and a more severe subluxation of the affected shoulder (t(51) = 14.0, p less than .01).

Aged↗
PubMed1989

Short-term and long-term memory deficit following intracarotid Amytal injection: further support for the memory consolidation hypothesis.

To test the three main hypotheses of the human amnesic syndrome (encoding, consolidation, retrieval), we designed an original protocol for memory assessment under Amytal that included, in addition to a retrograde memory measure, both short-term and long-term anterograde memory measures. Twenty epileptic patients with SEEG-confirmed unilateral temporal lobe foci were given right and left injections on successive days. Only the long-term memory measure for material presented under Amytal was significantly related to the presence of a temporal contralateral epileptogenic focus, even if it was assessed when the hemisphere had completely recovered from the effect of Amytal. Short-term memory deficits were observed equally often after injections ipsilateral and contralateral to the epileptogenic focus, and no retrograde amnesia was observed. These results are consistent with the consolidation hypothesis.

Adolescent↗
PubMed1983

Anterior callosotomy and chronic depth electrode recording in the surgical management of some intractable seizures.

Chronic depth electrode recording has proven to be a safe and indispensable tool for the investigation of intractable seizures. Anterior callosotomy appears as an excellent palliative treatment at least in bifrontal foci. It is hoped that chronic depth electrode recording will be used more widely before callosotomy in order to establish more clearly the best indication for such a surgical procedure.

Corpus Callosum↗
PubMed1983

[Incest].

Explore the source record for details and available documents.

Adolescent↗
PubMed1979

Relapsing neuropathy, cerebral atrophy and folate deficiency. A close association.

The case of a 48-year-old woman with a relapsing radial palsy which followed diarrheic episodes is reported. She had low folate concentrations in serum and cerebrospinal fluid, as well as low and borderline values of cerebrospinal fluid and erythrocyte folates. She had chronic gastrointestinal disease with edema of jejunal mucosa. The patient had some degree of cerebral atrophy. The effect of folate therapy on the neuropathy was spectacular. A beneficial effect of the therapy has been observed on both EEG tracings and neuropsychological performances after 6 months of treatment.

Atrophy↗
PubMed1979

[Binswanger's subcortical encephalopathy. Study of a case with predominant left hemispheric lesion (author's transl)].

We report the clinical and pathological study of a patient with vascular leucoencephalopathy almost restricted to the left posterior hemisphere. A 65 year--old right handed hypertensive woman has presented with a neuropsychological symptomatology of transcortical sensorial aphasia. We discuss the following points: 1) the patient's disease must be considered as Binswanger's subcortical encephalopathy despite the asymetric topography of the lesions ; 2) particular hemodynamic cerebral factors has possibly determined the asymetric nature of the disease ; 3) a lesion of the left temporo-parieto-occipital area that was strictly sub-cortical, with complete destruction of the posterior part of the arcuate fasciculus has presented with the clinical picture of a transcortical sensorial aphasia.

Aged↗