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Biomedical subjects

Y Robitaille

Publications and source records attributed to Y Robitaille.

At least 91 records · Page 5Linked to original sources
PubMed1991

Brain amino acid reductions in one family with chromosome 6p-linked dominantly inherited olivopontocerebellar atrophy.

We measured the levels of aspartate, glutamate, gamma-aminobutyric acid (GABA), and other amino acids in autopsied brain of 6 patients from one family (Pedigree S) with dominantly inherited olivopontocerebellar atrophy. A previous demonstration of reduced aspartate concentration in plasma of affected members of this family suggested the possibility of a generalized disorder of amino acid metabolism affecting the brain. As compared with the control levels, mean levels of aspartate and glutamate were markedly reduced by about 70 and 40%, respectively, in the degenerated cerebellar cortex from the patients. Since the cerebellar aspartate reduction likely exceeds the amount that could be explained by neuronal loss, other factors such as abnormal aspartate metabolism, neurotransmitter turnover, or both are probably involved. Mean aspartate, glutamate, and GABA levels were also reduced by about 10 to 30% in most of the 16 examined extracerebellar brain areas in which no or, at most, mild neuronal cell loss was observed by semiquantitative estimation. Concentrations of taurine, glutamine, and omicron-phosphoethanolamine were normal in all brain areas examined. Our biochemical data provide support to the presence of a generalized, but quantitatively mild, disturbance in amino acid metabolism in patients with olivopontocerebellar atrophy from Pedigree S. The regionally widespread amino acid reductions in the brain, of as yet unknown pathophysiological significance, could be due to a failure of one or more enzymes involved in aspartate and glutamate metabolism.

Adult↗
PubMed1991

Diagnosis and management of gliomatosis cerebri: recent trends.

Gliomatosis cerebri (GC) describes a diffuse overgrowth of the neuraxis by neoplastic glial cells with relative preservation of the underlying cytoarchitecture. Ten cases of GC are presented, followed by discussions of its radiological and pathological characteristics. The diagnosis of GC was formerly made only at autopsy. However, recent improvements in imaging and biopsy now allow for antemortem diagnosis. Immunocytochemistry for S-100 protein and glial fibrillary acidic protein (GFAP) in three open biopsies of early primary GC revealed diffuse proliferation of S-100 immunoreactive and GFAP-resistant small astrocytes. Magnetic resonance imaging appears to be the imaging modality of choice. T2-weighted images generally show contiguous high intensity signal in affected areas. Biopsy, either open or stereotactic, remains necessary for antemortem diagnosis. No treatment has proven effective for GC, the prognosis being poor. The authors also review theories of tumorigenesis of GC in an effort to explain its biology.

Adult↗
PubMed1991

Selective delayed alternation deficits in dominantly inherited olivopontocerebellar atrophy.

In order to characterize more completely the nature of the frontal lobe-type cognitive changes in patients with dominantly inherited olivopontocerebellar atrophy (OPCA) we administered two tasks sensitive to frontal system dysfunction, delayed alternation (DA) and delayed response (DR), to 12 patients from one OPCA family. Affected members from this family have previously been shown to have a marked and widespread cerebral (including frontal) cortical cholinergic reduction as severe as that observed in Alzheimer's disease. Performance on DA, but not on DR, was significantly impaired in the OPCA patients compared to that in the controls. We suggest that the DA deficits in OPCA could be a consequence of a loss of cholinergic innervation to orbitofrontal or possibly temporal cortical areas and/or damage to the integrity of the cerebello-frontal neuronal connections.

Adult↗
PubMed1991

Electroencephalography, magnetic resonance imaging and pathology in patients treated surgically for temporal lobe epilepsy.

In a consecutive series of 40 patients selected by EEG studies for surgical treatment of temporal lobe seizures, magnetic resonance imaging showed structural lesions in 25% and signal abnormalities, usually in the mesial temporal region, in another 35%. Pathological changes included structural lesions in over 30% of patients and sclerosis of the amygdala in almost half of the series. These findings further substantiate the implication of the amygdala in the pathogenesis of temporal lobe seizures with automatism and amnesia.

Amygdala↗
PubMed1991

Neuronal migration disorders: a contribution of modern neuroimaging to the etiologic diagnosis of epilepsy.

Computed tomography and magnetic resonance imaging enable the identification of neuronal migration disorders during life. Several specific syndromes have been identified and early diagnosis of previously unrecognized entities is now possible. We report 51 patients with imaging. Thirty-two had a single widespread cortical dysplastic lesion. Twenty-eight had focal corticectomies. From a pathological standpoint, these encompassed focal cortical dysplasia (14 cases) and forme fruste of tuberous sclerosis (10 cases). These two groups of patients were indistinguishable from the clinical and radiological standpoint. In only two was the MRI examination normal. In addition, there were 10 with bilateral perisylvian dysplasia, four with diffuse cortical dysplasia or the "double cortex" syndrome, three with hemimegalencephaly, one with megalencephaly, and one with nodular neuronal heterotopia. The electroclinical and imaging findings led to the development of specific surgical strategies for the alleviation of the intractable seizures in each of these radiologically-defined syndromes.

Adolescent↗
PubMed1991

Surgical treatment of intractable epilepsy associated with schizencephaly.

With the advent of magnetic resonance imaging, there has been an increased recognition of schizencephaly during life, especially in epileptic patients. We report our experience with the assessment and treatment of three patients with medically intractable seizures associated with this condition. The three men were aged 24 to 37 years. Two had delayed developmental milestones and hemiparesis or hemiplegia. One had normal development and a normal neurological examination. Seizures began between the ages of 15 and 19 years and lasted for 5 to 22 years before surgery. All had partial simple or generalized seizures with predominant electroencephalographic and electrocorticographic epileptic activity localized to temporal and frontal lobes on the side of the lesion. Neuropsychological assessment indicated widespread dysfunction maximal at the areas of predominant electroencephalographic abnormality. Magnetic resonance imaging demonstrated anterior parasagittal, parietal, and Rolandic cerebral clefts, with ventricular diverticuli, gray matter heterotopia, polymicrogyria, and a true agenesis of the corpus callosum in individual patients. The patients underwent temporal (one patient) and frontotemporal (two patients) lobectomies without additional neurological deficits or neuropsychological deterioration. Postoperative follow-up showed reduction in seizure frequency. We conclude that the surgical treatment of epilepsy is well tolerated in such patients, and their seizures can be alleviated by resection of epileptogenic areas.

Adult↗
PubMed1991

Surgical considerations in cerebral amyloid angiopathy.

In cerebral amyloid angiopathy, the contractile elements of the leptomeningeal and cortical arteries are replaced by noncontractile amyloid beta protein. The incidence of amyloid angiopathy increases with advancing age. It is associated with Alzheimer's disease and spontaneous cerebral hemorrhage. The latter can have the characteristic acute computed tomographic appearance of a hematoma at the cortex-white matter junction with extension of blood into the subarachnoid, subdural, and intraventricular spaces. Multiple hemorrhages are frequent. Additional bleeding can occur after evacuation of the hematoma, and postoperative hemorrhage can occur after cortical biopsy. To elucidate the role of surgery in this condition, we have reviewed 20 consecutive operated cases of cerebral amyloid angiopathy. A first group of 8 patients with senila dementia underwent cortical biopsy without resultant hemorrhage. A second group of 6 patients in good clinical condition had delayed evacuation of a spontaneous cerebral hematoma from cerebral amyloid angiopathy because of the radiological misdiagnosis of a hemorrhage within a tumor. One patient died of a pulmonary embolism, and another had subsequent multiple hemorrhages that were ultimately fatal. A third group of 6 patients in poor neurological condition had the acute evacuation of a spontaneous cerebral hematoma to relieve intracranial hypertension. All died or were severely disabled. One had repeated hemorrhages which added a progressively more severe organic dementia onto an initial hemiplegia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Developmental anterobasal temporal encephalocele and temporal lobe epilepsy.

The authors describe the association between an antero-basal temporal lobe encephalocele and medically intractable temporal lobe epilepsy in three patients treated successfully by surgery. Two men and one woman, aged 26 to 37 years (mean 31 years), had onset of complex automatism and generalized seizures in their second and fourth decades (mean age 22.7 years). They had been epileptic for 6 to 14 years (mean 8.3 years) before surgery. Preoperative electroencephalograms localized ictal epileptic activity to the left mesial temporal lobe in all cases, and neuropsychological testing revealed dominant temporal lobe dysfunction. Magnetic resonance (MR) imaging demonstrated an anteromedial basal temporal encephalocele extending into the pterygopalatine fossa through a bone defect at the base of the greater sphenoid wing in the region of the foramen rotundum and pterygoid process, a discrete center of embryonal chondrification. At surgery, the encephaloceles were found in front of the uncus, and an area of gliosis extended from the encephalocele to the amygdalohippocampal region. All patients have been seizure-free following anterior temporal resection and amygdalohippocampectomy including the encephalocele. These three cases delineate a condition of disordered embryogenesis wherein a developmental anterobasal temporal encephalocele acts as the substrate for temporal lobe epilepsy. This lesion may be diagnosed preoperatively with MR imaging and should be considered in the differential diagnosis of late-onset temporal lobe epilepsy.

Adult↗
PubMed1990

Glycerophosphoethanolamine concentration is elevated in brain of patients with dominantly inherited olivopontocerebellar atrophy.

We measured the concentration of glycerophosphoethanolamine (GPEA), a membrane breakdown product, in autopsied brain of 10 patients with dominantly inherited olivopontocerebellar atrophy (OPCA), a cerebellar ataxia disorder. As compared with the controls, mean GPEA levels were significantly elevated by 37-69% in 11 of the 15 brain areas examined, including extracerebellar brain regions in which no neuronal cell loss could be detected by semiquantitative estimation. Our data suggest the possibility of altered membrane phospholipid metabolism in OPCA which could be a contributing factor in the neuronal cell death.

Adult↗
PubMed1990

[3H]vesamicol binding in human brain cholinergic deficiency disorders.

We measured the binding of the vesicular acetylcholine transport blocker [3H]vesamicol (2-[4-phenylpiperidino] cyclohexanol; AH-5183) to autopsied frontal cortex and amygdala of patients from 4 disorders having a marked brain cholinergic reduction, namely Alzheimer's disease, Parkinson's disease with dementia, dominantly inherited olivopontocerebellar atrophy and Down's syndrome. Although mean activity of the specific cholinergic marker enzyme choline acetyltransferase (ChAT) was markedly reduced by about 60% in frontal cortex in the 4 patient groups and by 80% or greater in amygdala of the Alzheimer's and Down's syndrome patients, [3H]vesamicol binding density was, on average, either normal or only slightly reduced as compared with the controls. This discrepancy suggests that in human brain [3H]vesamicol binding is either not preferentially localized to cholinergic nerve endings or, in these cholinergic deficiency syndromes, a substantial proportion of the vesamicol binding sites persist on cholinergic nerve terminals despite loss of ChAT activity.

Acetylcholine↗
PubMed1990

Neuropeptide Y receptor binding sites in human brain. Possible alteration in Alzheimer's disease.

Neuropeptide Y (NPY) and peptide YY (PYY) receptor sites were studied in human brain using saturation binding experiments and receptor autoradiography. Additionally, the affinities and densities of [3H]NPY binding sites were compared in the temporal cortex, hippocampus and putamen of patients dying from Alzheimer's disease (AD) and aged matched controls. High densities of [3H]NPY binding sites were found in the putamen (192 +/- 32 fmol/mg protein), followed by the hippocampus (165 +/- 42 fmol/mg protein) and temporal cortex (118 +/- 19 fmol/mg protein). Receptor autoradiography revealed that these sites were especially concentrated in certain layers of the hippocampus, laminae I and IV-V of the temporal cortex and the amygdalo-hippocampal area. No significant changes in [3H]NPY binding affinities were seen between the AD and aged-matched groups (Kd ranges: 2.5-6.8 nM). However, significant decreases in [3H]NPY receptor densities (Bmax) were found in temporal cortex (-43%) and hippocampus (-49%) in AD brains. No significant change in [3H]NPY Bmax values was found in the putamen. It is therefore possible that decreases in [3H]NPY receptor densities may be associated to the degenerative process taking place in certain brain regions in AD, although further work will be necessary to confirm this hypothesis. Part of this work was presented at the 17th Annual Meeting of the Society for Neuroscience.

Aged↗
PubMed1990

Evaluation of an infant car seat program in a low-income community.

This study was designed to assess the influence of an infant car seat loan program on car seat utilization in a low-income community. An adjacent community, with no car seat program, was chosen for comparison. Systematic observations were made in the two neighborhoods, and this information was supplemented by telephone interviews. Greater use of infant seats was observed in the intervention community (41%) than in the control community (27%) for infants younger than 6 months old. The rate of observed utilization of infants between 7 and 18 months of age increased to 50% on average, but no significant differences were noted between the two communities. These findings suggest that a community-based loan program can produce short-term increases in car seat use rates for infants, even in a low-income community. A strategy to facilitate continued accessibility to such restraints is needed, however, to maintain these improvements.

Accidents, Traffic↗
PubMed1990

Morphologic heterogeneity of human adult astrocytes in culture: correlation with HLA-DR expression.

Human adult astrocytes derived from brain surgical resections showed marked morphologic heterogeneity when cultured in vitro, ranging from a flat, fibroblast-like appearance to process-bearing cells with little soma cytoplasm. The majority of cells were intermediate in morphology, bearing a prominent cytoplasmic cell body with processes radiating from them. The morphologic heterogeneity was more extensive than that of adult rat astrocytes, and was not correlated with the extent of attendant gliosis in the surgical specimens, or the site of the surgical resection. None of the human astrocytes expressed A2B5, thus preventing their classification on basis of lineage into type 1 or type 2 astrocytes. However, functional differences appear to exist between subpopulations of human astrocytes, since the proportion of process-bearing human astrocytes that expressed HLA-DR in vitro was significantly greater than that found for flat astrocytes.

Adolescent↗
PubMed1990

Spinal synovial cyst: case report using magnetic resonance imaging.

The case of a 65-year-old woman who developed a spinal synovial cyst at the L4-5 disk space is reported. Her clinical signs and symptoms are presented. A comparison among her preoperative myelogram, computed tomography scan, and magnetic resonance imaging showed magnetic resonance imaging to be more accurate in detailing both the intraoperative and pathological findings.

Aged↗
PubMed1990

Neurochemical deficits in pathological brain aging: specificity and possible relevance for treatment strategies.

Normal brain aging is accompanied by the losses of certain neuronal populations and the appearance of structures such as neuronal plaques and neurofibrillary tangles. Additionally, various neurotransmitter systems are altered in the elderly, although marked variations are observed between individuals, suggesting important differences between successful and unsuccessful aging. In certain pathological conditions, only certain features of normal aging are exacerbated. For example, the densities of forebrain cholinergic neurons are markedly decreased in cortical and hippocampal (but not striatal) areas in Alzheimer's disease. We discuss here the comparative alterations of cholinergic markers in certain neurological disorders such as Alzheimer's disease, Parkinson's disease, and the combined pathology. Differential alterations of brain cholinergic profile are observed in each disorder, this most likely having functional significance. We also found that muscarinic receptors of the M2 subtype act as negative autoreceptors to decrease brain acetylcholine release, whereas nicotinic agonists induced the opposite effect. This suggests that blockade of negative M2 or stimulation of positive nicotinic autoreceptors could have beneficial effects in Alzheimer's disease. Additionally, modulation of heteroreceptor activation such as the serotonergic or interleukin-2 sites located on or in proximity to cholinergic nerve terminals could offer alternate strategies for the treatment of cholinergic deficits in pathological brain aging.

Aging↗
PubMed1990

Substitution of the U3 long terminal repeat region of the neurotropic Cas-Br-E retrovirus affects its disease-inducing potential.

The Cas-Br-E and ts-Mo BA-1 murine leukemia viruses (MuLV) induce a spongiform neurodegenerative disease with different clinical manifestations, namely, either hind limb paralysis (Cas-Br-E) or tremors, spasticity, and hind limb weakness (ts-Mo Ba-1). We constructed the chimeric NEBA-1 MuLV by replacing the long terminal repeat of Cas-Br-E MuLV with that of ts-Mo BA-1 MuLV. In SWR/J or CFW/D mice, NEBA-1 MuLV induced an ataxic neurological disease characterized by clinical signs different from those induced by both parents. Although NEBA-1 MuLV did not induce lesions in novel brain areas, the spongiform lesions were more severe in deep cerebellar nuclei and in the spinal cord than those found in paralyzed mice inoculated with Cas-Br-E MuLV. By in situ hybridization, we found that the distribution of the spongiform lesions closely correlated with the distribution of the infected central nervous system cells. In the spinal cord, a close correlation was found between the number of infected cells and the severity of the spongiform degeneration. Sequencing of the substituted ts-BA-1 MuLV fragment and comparison with homologous sequences of Cas-Br-E and Moloney MuLV showed differences mainly in the U3 tandem direct repeats. Our results show that a few modifications within the U3 long terminal repeat allow the virus to cause more severe lesions in some central nervous system regions and that the severity of the spongiform degeneration correlates with the level of viral replication.

Animals↗
PubMed1989

Cerebellar [3H]inositol 1,4,5-trisphosphate binding is markedly decreased in human olivopontocerebellar atrophy.

We examined the behaviour of [3H]inositol-1,4,5-trisphosphate (IP3) binding in autopsied cerebellar and cerebral cortex of 10 neurologically normal controls and 8 patients with end-stage olivopontocerebellar atrophy (OPCA), a cerebellar ataxia disorder characterized histologically by severe degeneration of Purkinje cells. [3H]IP3 binding to normal human cerebellar cortex was 6-15 times higher than in cerebral cortex. As compared with the controls, mean [3H]IP3 binding to cerebellar cortex was markedly reduced by 61% in the OPCA patients whereas levels were normal in frontal and occipital cortices. Since the Purkinje cell dendrite receives neuronal input from granule cells and climbing fibers utilizing glutamate and aspartate, respectively, as neurotransmitters, the reduced IP3 binding in OPCA cerebellar cortex may reflect a loss of Purkinje cells containing these excitatory amino acid receptors linked to the phosphatidylinositide second messenger system. Our data suggest that in humans, IP3 receptors may be highly localized to the Purkinje cell dendrite.

Adult↗