Search PubMed⌕ Search

Biomedical subjects

D Seilhean

Publications and source records attributed to D Seilhean.

49 records · Page 3Linked to original sources
PubMed1995

[Narcolepsy disclosing neurosarcoidosis].

A 37-year-old man developed excessive daytime sleepiness, sleep attacks and cataplexy revealing an hypothalamic tumour. Multiple Sleep Latency Tests (MSLT) were characteristics of narcolepsy. Tissue typing was positive for HLA DR2 and DQ1. Most cases of narcolepsy are idiopathic without any evidence of brain pathology. Although symptomatic narcolepsy may occur occasionally with diencephalic lesions. The relationship between narcolepsy with diencephalic lesions is unsettled and will be discussed.

Adult↗
PubMed1995

[Neuropathology of non conventional infectious agents or prions].

The neuropathological diagnosis of infections by non conventional agents relies on four lesions: astrocytic gliosis (cell hypertrophy and proliferation) usually contrasting with absent mononuclear cell infiltrates (lymphocytes, monocytes-macrophages, and/or microglia) revealed by conventional techniques, and neuronal loss in the most affected areas are little specific findings. Amyloid plaques that are inconstantly found, and spongiosis of gray matter, a characteristic and very frequent finding, are most specific. PrP immunohistochemistry brings additional data. The main diagnostic difficulties are emphasized, and guidelines for Pathological studies are recalled.

Animals↗
PubMed1994

[Alzheimer disease. Role of beta A4 peptide and cerebral amyloid substance].

Deposition of large quantities of amyloid substance in the walls of the cerebral vessels and in the core of the senile plaques is characteristic of Alzheimer's disease. beta A4 peptide, the main component of the amyloid substance, is a product of a larger amyloid precursor protein which has the structure of a transmembrane receptor and is widely distributed throughout the body. The pathway leading to beta A4 is not yet fully established but could involve lysosomal degradation. It has been suggested that the beta A4 peptide is of neuronal or vascular origin. The beta A4 peptide is found in diffuse deposits in the cortex and cerebellum as well as in the basal ganglia before the classic senile plaques appear, mainly in layer III of the cerebral cortex. These diffuse deposits are devoid of degenerating neurites (i.e. containing abnormally phosphorylated tau protein). The classical senile plaques contain numerous degenerating neurites linking them to the connective network of the cortex. The intellectual deficit is correlated significantly to the density of the classical senile plaques but not to the density of the diffuse deposits. Although a mutation of the gene coding for the beta A4 peptide appears to be sufficient to induce (or accelerate) Alzheimer's disease, this is undoubtedly an exceptional mechanism. Certain mutations involving the beta A4 precursor protein gene increase in vitro the production of beta A4. The molecular and morphological steps leading, from the accumulation of the peptide (which in itself has no clinical expression) to the neurofibrillary pathology of the senile plaques and of the neurones (which are strongly correlated with clinical dementia), remain hypothetical.

Aged↗
PubMed1994

Dementia in two histologically confirmed cases of multiple sclerosis: one case with isolated dementia and one case associated with psychiatric symptoms.

During the past 10 years, considerable attention has been devoted to cognitive impairment in multiple sclerosis. Occasionally this impairment may be so severe that multiple sclerosis presents as a dementia associated with only minor neurological signs and symptoms. The cases of two women affected by multiple sclerosis who presented with a pure dementia are reported. In the first patient, a progressive apragmatic behavioural disturbance with reduced short term memory and learning abilities were the main clinical features. Neuropathological examination of the brain disclosed numerous plaques in the periventricular white matter, with severe atrophy of the corpus callosum. Plaques were also seen in the white matter of both hippocampus and in the columns of the fornix. The impairment of short term memory could be linked to these lesions. Behavioural changes were probably related to the bilateral lesions of the long associative bundles that disconnected the frontal lobes from other parts of the cerebral hemispheres. In the second patient, visual hallucinations were associated with cognitive dysfunction. MRI showed large plaques in the white matter of both left frontal and temporal lobes. Smaller plaques were also present in the periventricular white matter of the occipital lobes, the nature of which were confirmed by a stereotactic biopsy.

Adult↗
PubMed1993

HIV-1-associated cognitive/motor complex: absence of neuronal loss in the cerebral neocortex.

We performed a postmortem morphometric study in six AIDS patients and six controls to determine if a neocortical neuronal loss occurs in HIV-1-associated cognitive/motor complex. Patients were selected during a prospective study including psychometric evaluation and neuroimaging, and none had focal lesions. Two had HIV-1-associated myelopathy with mild cognitive impairment, and four had HIV-1-associated dementia complex. Planimetry did not show any cerebral atrophy. Cortical thickness, mean neuronal size, and mean neuronal densities in Brodmann's areas 4, 9, and 40 were not statistically different in patients and controls. There were no significant changes in neuronal densities of columnar and laminar samples, indicating that there was neither global nor selective neuronal loss. HIV-1-associated cognitive/motor complex is not necessarily related to neocortical neuronal loss, but could be due to subcortical lesions or metabolic dysfunction.

Adult↗
PubMed1993

A brain bank in a neuropathology laboratory (with some emphasis on diagnostic criteria).

The Brain Bank of La Salpêtrière Hospital (Paris) is implanted in a neuropathology laboratory. It is multipurpose, prospective, and "free of charge" for the users. Protocols are prospectively established, in collaboration with the neuroscientists. One of our major difficulties in the collection of cases concerns presently the controls: the neurological status of patients coming from Neurology departments has usually been correctly assessed but those patients are bad controls. The normality of the neurological status of patients dying in other departments is difficult to assess retrospectively. A general autopsy is performed in each case. Several systematic sampling and fixation procedures are currently in use; their pros and cons are discussed. The main safety problem we are confronted with is the risk of HIV and Jakob-Creutzfeldt transmission. We try to standardize our diagnostic procedures; criteria used in Alzheimer's disease, Parkinson's disease, Huntington's chorea are briefly reviewed. We plan, in the future, to standardize our procedures for control cases. The Brain Bank has had a very positive impact on the way this neuropathology laboratory works: it introduced new techniques; on the other hand, the adequate processing and diagnosis of the samples was, in many aspects, simplified by the collaboration with the neuropathology department. The demand for human brain samples is steadily increasing in Neuroscience, for at least 2 reasons: 1. some diseases are specifically human and lack adequate animal models (Alzheimer's disease, multisystem atrophy), or animal models may appear irrelevant in some aspects (multiple sclerosis) or finally, results obtained in animal models may have to be confronted with human pathology (AIDS ...) 2. many aspects of human neuroanatomy can not be extrapolated from animal data There are many ways of organizing a brain bank and no golden standard (Swaab et al., 1989): the neuroscientist himself may collect the samples in a given pathology or the neuropathologists may modify their practice to provide adequate samples to the neuroscientists. When the neuroscientist himself collects his own samples, he obviously proceeds more rapidly. However, he is confronted with the difficult problem of the controls, which require both a clinical follow-up and a pathological check up of the tissues, both of which may be difficult to obtain in a research unit. In our opinion, the neuropathologists are the natural "brain bankers": they are indeed naturally "rich", their job being precisely to collect human samples, in connection with the clinicians.(ABSTRACT TRUNCATED AT 400 WORDS)

Brain↗
PubMed1992

Morphology of demyelination in the human central nervous system.

The principles of the neuropathological classification of disorders of central nervous system myelin are recalled. They are illustrated by a few selected examples. Dysmyelination is characterized by the production of an abnormal and unstable myelin sheath; it is often associated with hypomyelination (paucity of myelin formation) and is due to metabolic disorders. It is the main process in leukodystrophies. Storage of different lipids (e.g. sulfatides, long-chain fatty acids) or associated pathology of various cell types (in Alexander's disease, for example) are used for classifying these disorders. Biochemical and genetic characterizations are presently ongoing. Demyelination is the destruction of apparently normal myelin. It is often followed by remyelination. Our present knowledge on the neuropathology of multiple sclerosis, the most common demyelinating disease, is summarized. Cell-mediated demyelination affects the myelin sheaths for an obscure reason. The causes of the multifocal and sharply demarcated plaques, and of the fading of the remyelination process at the edge of some plaques, are not clear. A few examples of demyelinating diseases of known etiology and of various mechanisms are given. The similarities between acute disseminated leukoencephalitis and experimental autoimmune encephalitis are stressed. In progressive multifocal leukoencephalopathy, chronic infection of oligodendrocytes by JC virus induces poorly defined areas of demyelination. In AIDS, the pathogenesis of the myelin change is unclear. Macrophages may be responsible. Toxic and vascular disorders provide also good models for the understanding of mechanisms of demyelination.

Central Nervous System Diseases↗
PubMed1991

[Anatomy and memory].

Bilateral lesions involving the medial aspect of the hemisphere may induce pure amnestic syndromes. Which neural elements have to be destroyed remains open to question: hippocampus, mamillary body, dorso-medial nucleus of the thalamus play probably a role at one point or another of the memory process. Lesions of the dorso-lateral part of the frontal lobe disturb the chronological order of memories. Il has been suggested that 2 systems were involved: the first one is hippocampo-mamillo-thalamic (Papez circuit), the second one is amygdalo-thalamo-frontal. The respective role of each of these circuits remain controversial.

Brain↗