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Biomedical subjects

B Lechevalier

Publications and source records attributed to B Lechevalier.

At least 37 records · Page 2Linked to original sources
PubMed1995

Cytoplasmic body myopathy: familial cases with accumulation of desmin and dystrophin. An immunohistochemical, immunoelectron microscopic and biochemical study.

Muscle biopsy samples from five patients with cytoplasmic body myopathy (CBM) were investigated by immunohistochemical (antibodies to desmin, actin, dystrophin, spectrin, alpha actinin and utrophin), immunoelectron microscopic (antibodies to desmin, actin and dystrophin) and biochemical (desmin, dystrophin, actin and utrophin western blots) methods. Using immunofluorescence it was shown that the centers of cytoplasmic bodies (CB) were stained by anti-actin, anti-utrophin and three different anti-dystrophin antibodies. The peripheries were labeled by the anti-desmin antibody. Moreover, fibers containing CB showed a markedly increased staining of their entire sarcoplasm with the anti-desmin antibody. Using immunoelectron microscopy it was shown that anti-dystrophin antibodies selectively stained the external limit of the central granular region. Anti-desmin antibody labeled the filamentous halo, and anti-actin antibody stained the central core and the radiating filaments. Biochemical studies showed storage of desmin and dystrophin, both of normal molecular weight. Our results suggest that CBM should be considered along with a wider group of intermediate filament pathologies that include desmin-storage myopathies.

Antibodies↗
PubMed1995

PET imaging of neocortical monoaminergic terminals in Parkinson's disease.

Post-mortem neurochemical studies in Parkinson's disease (PD) have shown that, in addition to the typical nigro-striatal dopamine denervation, there exists a concomitant neocortical monoamine fibre deafferentation (of variable severity) whose role in motor, and especially in associated cognitive and affective impairment, remains elusive. We have extensively examined whether PET imaging with 11C-S-Nomifensine (11C-NMF), a radioligand of the dopamine and norepinephrine presynaptic reuptake sites which has been used so far to investigate the striatum, could provide a method for assessing in vivo the neocortical monoamine terminal loss in PD; previously, this has been a little addressed and controversial issue. To this end, we prospectively selected a highly homogeneous sample of nine non-demented, non-depressed idiopathic PD patients with mild to marked side-to-side asymmetry in motor impairment. In addition to recovering the previously-reported correlations with putaminal 11C-NMF specific uptake asymmetries, the clinical motor asymmetries also significantly correlated in the clinically expected direction to neocortical (especially frontal) 11C-NMF asymmetries, suggesting the monoamine neocortical denervation might play a direct role in motor impairment in PD. These results demonstrate that it is possible to assess in vivo the neocortical monoamine terminal loss, and to elucidate its potential role in the complex cognitive and affective impairment, in both PD and atypical degenerative parkinsonism.

Aged↗
PubMed1995

Topographic EEG activations during timbre and pitch discrimination tasks using musical sounds.

Successive auditory stimulation sequences were presented binaurally to 18 young normal volunteers. Five conditions were investigated: two reference tasks, assumed to involve passive listening to couples of musical sounds, and three discrimination tasks, one dealing with pitch, and two with timbre (either with or without the attack). A symmetrical montage of 16 EEG channels was recorded for each subject across the different conditions. Two quantitative parameters of EEG activity were compared among the different sequences within five distinct frequency bands. As compared to a rest (no stimulation) condition, both passive listening conditions led to changes in primary auditory cortex areas. Both discrimination tasks for pitch and timbre led to right hemisphere EEG changes, organized in two poles: an anterior one and a posterior one. After discussing the electrophysiological aspects of this work, these results are interpreted in terms of a network including the right temporal neocortex and the right frontal lobe to maintain the acoustical information in an auditory working memory necessary to carry out the discrimination task.

Adolescent↗
PubMed1995

Healthy aging, memory subsystems and regional cerebral oxygen consumption.

The present study was designed to search for concomitant age-related changes in memory subsystems, defined according to current structural theories, and resting oxygen consumption in selected brain regions. We have investigated a sample of subjects between 20 and 68 years of age and strictly screened for their good health. We applied in the same subjects a battery of neuropsychological tests selected to investigate several memory subsystems, and high-resolution positron imaging with stereotaxic localization to study a purposely limited number of cerebral structures, selected on a priori hypotheses to match the different memory subsystems. Our results showed significant age-related changes in performance on some tests, consistent with the literature, including an increase in semantic memory and a decrease in both working memory (central executive system) and verbal episodic and explicit memory. There was also an age-related linear decrease in global brain oxygen consumption which regionally reached statistical significance for the neocortical areas and the left thalamus. There was a limited number of significant, age-independent correlations between the raw psychometric test scores and resting regional oxidative metabolism. Consistent with our present understanding of the functional anatomy of memory, the Associate Learning scores (verbal episodic and explicit memory) were positively correlated with left hippocampal and thalamic metabolism. The positive relationships found between right hippocampal metabolism and performance in the Associate Learning and the Brown-Peterson tests were less expected but would be consistent with findings from recent PET activation studies. The results from this investigation are discussed in the light of current knowledge concerning the neuropsychology and the neurobiology of both aging and memory.

Adult↗
PubMed1995

[Myositis ossificans progressiva].

BACKGROUND: Myositis ossificans progressiva is a rare progressive disease of connective tissue with a poor prognosis. CASE REPORT: A 16 year-old girl suffered from lameness of her right leg associated with inguinal swelling. Progressive aggravation of pain with extension of swelling to the posterior part of her thigh required an X-ray examination which showed hip dysplasia and calcifications around the hip. Angiography was normal; a diagnosis of hematoma was suggested by scannography and bone scintigraphy, but biopsy showed features of nodular fasciitis. The association of progressive ectopic ossification to malformation of the big toe led to diagnosis of myositis ossificans progressiva. CONCLUSIONS: Congenital malformations, most commonly of big toes and thumbs, are important for distinguishing myositis ossificans progressiva from other diseases of muscle.

Adolescent↗
PubMed1995

Disorders of auditory identification in dementia of the Alzheimer type.

Fifteen patients with probable DAT and 18 matched controls were given tests that required the identification of verbal (phonemes and words) and non verbal (sounds and melodies) stimuli. In all tests, DAT patients made significantly more errors than controls. Errors predominated in non verbal tests in both groups. DAT patients (and, to a lesser degree, control subjects) made almost exclusively acoustic errors in word-identification, while errors in the identification of sounds and melodies could be either semantic or acoustic. Some categories of errors were observed predominantly in DAT patients. These results suggest that, in addition to their cognitive impairment, DAT patients have a specific deficiency of central auditory perception.

Aged↗
PubMed1995

A PET study of the functional neuroanatomy of writing impairment in Alzheimer's disease. The role of the left supramarginal and left angular gyri.

A dissociation in the central processes of spelling, with preferentially lexical over phonological impairment, frequently affects patients with early Alzheimer's disease. The aim of this work was to test whether dissociations in the language domain in Alzheimer's disease can be exploited with PET to assess the neural basis of cognition. To this end, we studied the functional neuroanatomy of writing impairment in Alzheimer's disease by means of PET measurements of the local cerebral glucose utilization and neuropsychological tests specially designed to assess the phonological and lexical components of writing. We analysed the performance in written spelling of irregular words and non-words of 11 right-handed patients with mild-to-moderate Alzheimer's disease. For each patient, we calculated a residual phonological score and a residual lexical score, based on a cognitive interpretation of the errors according to the item category. In each of these 11 patients, using PET, we measured the resting-state utilization of glucose in the left supramarginal gyrus and the left angular gyrus, two cortical regions selected a priori because of their presumed role in the central processes for spelling, and identified on CT scans obtained according to stereotaxic references and coregistered with PET. To assess the relationships between the neuropsychological scores and the metabolic data, we used the 'ratio paradigm', the sensitivity of which has been previously documented in cognitive-metabolic correlative PET studies of Alzheimer's disease that were less focused than the present study in both cognitive and anatomical terms. We found a highly significant positive correlation between phonological score:lexical score neuropsychological ratios and corresponding supramarginal gyrus:angular gyrus metabolic ratios. These findings further support the role of these two left-sided temporo-parietal regions in the central processes of writing and show that the neuropsychological dissociations in early Alzheimer's diseases can be exploited to further our understanding of the functional neuroanatomy of cognitive operations. The role of focal, as compared with more diffuse, brain damage in the development of impaired written language of central origin in Alzheimer's disease is also discussed.

Aged↗
PubMed1995

[Vascular dementia: clinical and radiological characteristics in 26 cases].

Twenty six patients with vascular dementia were studied. Five of them only, were referred for a cognitive decline and all the others because of focal neurological symptoms or a stroke. Twelve patients had a previous history of stroke and 21 an history of high blood pressure. Twenty three patients had gait disturbances. CT scanner and MRI showed a large proportion (23 patients) of lacunar or small sub-cortical strokes. Leuko-araiosis was present in 21 patients and cortical stroke only in 6. Finally, the lack of information concerning the onset and the course of the cognitive decline in 12 patients explain the difficulties to fulfill the criteria in some diagnostic evaluation scores particularly those of the DSM III R.

Aged↗
PubMed1994

[Multimodal or multisensorial agnosia?].

A 75 year-old right handed woman had persistent right homonymous hemianopia and alexia without agraphia caused by a haemorrhagic stroke of the left occipito-temporal region. Six months later she suffered sudden onset visual and auditory agnosia, following a second haematoma, contralateral to the first one, in the right occipito-temporal region including the lingual and fusiform gyri. None of the disorders concerned semantic representation, so that an asemantic agnosia was excluded. Her performance in naming and recognition tests, in both visual and auditory modalities, demonstrated a wide range of responses and errors. The pattern of visual symptoms suggested "associative visual agnosia narrow sense" (Farah, 1990); auditory agnosia concerned only the non verbal stimuli. These findings were discussed in terms of anatomical mechanisms subserving perceptual, semantical, visuo and auditory-verbal representation. In this case, visual and auditory, agnosia appears to be independent.

Aged↗
PubMed1993

[Extrapulmonary and disseminated pneumocystosis in HIV infection].

Three cases of extrapulmonary disseminated Pneumocystis carinii infection are reported. All 3 patients had HIV infection with less than 50 CD4 lymphocytes per cubic millimeter and were having aerosols of pentamidine as prophylactic treatment of pneumocystosis. P. carinii may invade numerous organs and in particular the liver, spleen and bone marrow. Extrapulmonary lesions, often pan-symptomatic, are to be feared in deeply immunodepressed patients receiving prophylactic aerosols of pentamidine. Infection of the choroid can be detected by systematic ophthalmoscopy. An early diagnosis raises hopes of a good, if temporary, response to treatment.

AIDS-Related Opportunistic Infections↗
PubMed1993

Characteristics and evolution of writing impairment in Alzheimer's disease.

Rapcsak et al. (Archs Neurol. 46, 65-67, 1989) proposed a hypothesis describing the evolution of agraphic impairments in dementia of the Alzheimer type (DAT): lexico-semantic disturbances at the beginning of the disease, impairments becoming more and more phonological as the dementia becomes more severe. Our study was conducted in an attempt to prove this hypothesis on the basis of an analysis of the changes observed in the agraphia impairment of patients with DAT. A writing test from dictation was proposed to 22 patients twice, with an interval of 9-12 months between the tests. The results show that within 1 year there was little change in the errors made by the patients in the writing test. The changes observed however were all found to develop within the same logical progression (as demonstrated by Correspondence Analysis). These findings made it possible to develop a general hypothesis indicating that the agraphic impairment evolves through three phases in patients with DAT. The first one is a phase of mild impairment (with a few possible phonologically plausible errors). In the second phase non-phonological spelling errors predominate, phonologically plausible errors are fewer and the errors mostly involve irregular words and non-words. The last phase involves more extreme disorders that affect all types of words. We observe many alterations due to impaired graphic motor capacity. This work would tend to confirm the hypothesis proposed by Rapcsak et al. concerning the development of agraphia, and would emphasize the importance of peripheral impairments, especially grapho-motor impairments which come in addition to the lexical and phonological impairments.

Agraphia↗
PubMed1992

[Familial parkinsonian syndrome with athymhormia and hypoventilation].

Five cases of parkinsonism with athymhormia observed in a single family are reported. Death caused by central respiratory disorders occurred after 6 to 8 years of progressive course. In 2 cases with autopsy, there was a severe neuronal loss predominant in the substantia nigra. Other brain stem nuclei (locus coeruleus, dorsal motor nucleus of the vagus nerve, nucleus of the tractus solitarius) were involved, as well as the striatum, pallidum and frontal cortex. No Lewy body was seen. In the surviving patient, positron emission tomography demonstrated, 4 years after the onset, a bilateral frontal hypometabolism. This disease is a rare variety of familial parkinsonism of dominant inheritance, already reported in 2 Canadian families by Perry et al. (1975) and Purdy et al. (1978) and in a family of West Virginia by Roy et al. (1988). The respiratory disorders can be explained by the involvement of the dorsal medullary nuclei. The peculiar neuropsychological disorder and motor slowing are best accounted for by the functional impairment of both motor and limbic striato-pallido-thalamo-frontal loops.

Cerebral Cortex↗
PubMed1992

[Diffuse cerebral gliomatosis. An anatomoclinical case].

A 52-year old man had a generalized seizure followed by progressive memory disturbances, affective changes, right hemiplegia and aphasia. He died 4 years later after a period of coma. Neuropathological findings included slight cortical atrophy, pallor of the centrum ovale, and infiltration of the cortex and subcortical white matter by neoplastic glial cells, with neither major neuronal loss nor spongiosis. Microglial rod cells were observed. The gliomatosis extended within the thalamus and subthalamic area on both sides, whereas the brain stem was much less involved. The spinal cord and peripheral nerves were not examined. Abnormal glial cells were stained by the glial fibrillary acid protein, which confirms the astrocytic differentiation of the tumoral cells.

Brain↗
PubMed1992

[Intracranial cavernous angioma].

Cavernous angiomas are vascular malformations that belong to the group of hamartomas. Evidence to support the hypothesis that some intracranial cavernous angiomas are benign vascular tumors is lacking. As they are angiographically occult, cavernous angiomas were largely overlooked and were considered rare before CT scan and MRI became available. Both of these techniques provide a quick and accurate diagnosis in cases of epilepsy, brain hemorrhage or intracranial hypertension. Most of the hemispheric cavernous angiomas are situated subcortically, in the neighborhood of the rolandic fissure. In the brain stem, they can be found mostly in the pons. Cerebellum and spinal cord are seldom involved. Cavernous angiomas may occur in children, as well as in familial forms, or in association with other visceral locations. It is important to know that some cavernous angiomas are able to grow, owing to a variety of mechanisms, which may result in rupture and cerebral hemorrhage. The improvement of both imaging and surgical techniques have reduced the risks of death or heavy sequelae. Some deeply located cavernous angiomas, however, are still inaccessible to surgery.

Adolescent↗