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O Robain

Publications and source records attributed to O Robain.

At least 37 records · Page 2Linked to original sources
PubMed1994

Development of mossy fiber synapses in hippocampal slice culture.

The mossy fiber synaptogenesis has been studied in hippocampal slice cultures. In vivo mossy fiber terminals contact the thorny excrescences of CA3 pyramidal neurons over a restricted portion, i.e. the proximal part of the apical dendrite. In organotypic cultures mossy fibers expand their terminal field and invade the infrapyramidal area of the CA3 region and the supragranular layer of the dentate gyrus. Newly formed mossy fiber synapses in CA3 region were examined, through electron microscopy, in cultures taken at various time intervals. The main events of the formation of newly formed mossy fiber synapses can be summarized as follows. During the first week following explantation mossy fiber axons contact the dendritic shaft of the pyramidal dendrite and establish both symmetrical and asymmetrical contacts. Subsequent modifications occur in the postsynaptic portion facing the mossy fiber bouton: (i) a massive accumulation of polyribosomes and coated vesicles in the subsynaptic cytoplasm; (ii) undulations of the plasma membrane; (iii) disappearance of neurotubules at postsynaptic sites and appearance of a fine network of filamentous material. Later on in culture, complex giant spines invaginate within the synaptic bouton. In conclusion this study shows that CA3 pyramidal neurons following deafferentation retain the capacity to form thorny excrescences, when contacted by mossy fibers. Moreover these results suggest a crucial role for mossy fibers to induce the formation of thorny excrescences in an heterotopic localization, i.e. over the basilar dendrites of CA3 pyramidal neurons.

Animals↗
PubMed1994

Kainate-induced apoptotic cell death in hippocampal neurons.

We have examined the role apoptosis plays in epileptic brain damage using intra-amygdaloid injection of kainate. With the silver staining technique of Gallyas, argyrophylic (dying) neurons were observed, a few hours after the injection, in the amygdala and in the vulnerable pyramidal neurons of the hippocampal CA3 region. In both areas, cell death has apoptotic features, including: (i) nuclear chromatin condensation and marginalization with light and electron microscopy; (ii) DNA fragmentation with a typical ladder pattern on agarose gel electrophoresis; (iii) positive nuclear labelling with a selective in situ DNA fragmentation staining method. Combined in situ DNA labelling and silver staining showed that the DNA fragmentation occurred in dying neurons. CA1 or granule cells which do not degenerate following intra-amygdaloid injection of kainate were not stained with the in situ DNA labelling or the argyrophylic technique. Administration of diazepam blocked the kainate-induced seizures and prevented DNA fragmentation in CA3 but not in the amygdala. Therefore, apoptosis contributes to the local and distant damage induced by kainate.

Animals↗
PubMed1994

Iatrogenic Creutzfeldt-Jakob disease in three growth hormone recipients: a neuropathological study.

Since 1985, several cases of Creutzfeldt-Jakob disease, occurring after a treatment by human cadaveric hormone have been reported. Three new iatrogenic cases observed in French patients (two children and one young adult) are described here. Neuropathological study displayed the classical aspects of previously reported sporadic cases of Creutzfeldt-Jakob disease in adults, including severe cortical spongiform change with numerous vacuoles within neuronal dendrites, diffuse astrogliosis and neuronal loss. In addition, the iatrogenic cases described here included two more unusual points: (i) they were homozygotic for the PrP gene on codon 129 and therefore a genetic predisposition could be suspected; (ii) numerous kuru plaques were scattered in the cerebral cortex, the subcortical white matter and in the cerebellar cortex. They were decorated with a PrP monoclonal antibody, but not with a beta A4 antibody. This last point underlines the similarities between iatrogenic Creutzfeldt-Jakob disease and kuru.

Adult↗
PubMed1994

Reappraisal of Rasmussen's syndrome with special emphasis on treatment with high doses of steroids.

Eight patients with Rasmussen's syndrome and epilepsia partialis continua were treated with high doses of steroids, including pulses of methylprednisolone and prednisone in decreasing doses. Three patients exhibited clinical, radiological, or histological evidence of bilateral involvement. Epilepsy and focal deficit decreased within six months in seven patients. Only five patients, in whom steroid treatment had begun less than 15 months after the onset of epilepsia partialis continua, experienced a lasting effect although they had periodic episodes of transient relapse. Treatment with high doses of steroids seems advisable during the first year after onset of epilepsia partialis continua, before hemiplegia has developed and in cases with bilateral involvement.

Adolescent↗
PubMed1994

[Biopercular polymicrogyria associated with congenital ophthalmoplegia caused by nuclear lesion of the common oculomotor nerve].

Developmental pseudobulbar palsies seem to be different from the adult form described by Foix, Chavany and Marie. They usually include a major speech delay and severe epileptic seizures. In one clinicopathological case, neuroradiological imaging showed a macrogyric aspect of both rolandic operculi and unilateral destruction of pes pedunculari. Microscopic examination showed a four-layered polymicrogyria involving the first temporal gyrus and in the brainstem a selective destruction of the left oculomotor nucleus. Thus, the macrogyric aspect could be related to post migratory disorder occurring late in the cortical development. The brain stem lesion, destroying unilaterally the third cranial nerve nucleus gives a good example of the complex somatotopia of this oculomotor nucleus.

Abnormalities, Multiple↗
PubMed1994

Infantile spasms: a pathophysiological hypothesis

Clinical and electroencephalogram (EEG) observations permit a hypothesis for the pathophysiology of infantile spasms. The triggering area(s) for spasms is probably cortical. Diffuse hyperexcitability of the immature cortex and/or diffusion of the epileptic process from a focal abnormality would allow development of hypsarrhythmia. Cortical maturation from posterior to anterior might account for the location of causative focal abnormalities. In cryptogenic West syndrome, the predominant pathophysiologic process may be diffuse cortical hyperexcitability, explaining the severe developmental deterioration at the onset of spasms. In symptomatic West syndrome with focal pathology, the initial deterioration is often less striking, suggesting that the predominant effect is diffusion of the epileptic process. The pattern of eventual cognitive deficits follows a similar pattern.

Journal Article↗
PubMed1992

Unlayered polymicrogyria and agenesis of the corpus callosum: a relevant association?

Three anatomical cases of unlayered polymicrogyria associated with agenesis of the corpus callosum and heterotopias are presented. The cortical dysplasia includes: (1) thin unlayered cortical mantle with radial disposition but no horizontal organisation of the neurons; (2) microgyria with fused molecular layers; and (3) persisting transitory cells in the molecular layer (Cajal-Retzius cells, subpial granular layer). A Golgi study of the cortex in one case shows abnormal orientation of the neuronal dendritic tree in the superficial area along the fused molecular layers. Heterotopias are of two types: scattered neurons in the subcortical region and in layer I; and nodular heterotopias in the paraventricular region and in centrum semi ovale. This type of cortical dysplasia differs from the classical four-layered microgyria and is similar to the cortical anomalies described in Aicardi syndrome. One case presented here has Aicardi syndrome, while the two others, one girl and one boy, do not meet the criteria for Aicardi syndrome; in particular, they do not display chorioretinal lacunae. Nevertheless, this neuropathological association is responsible for severe mental retardation and epilepsy, and incites the search for a genetic origin like that in Aicardi syndrome.

Abnormalities, Multiple↗
PubMed1992

Microgyric and necrotic cortical lesions in twin fetuses: original cerebral damage consecutive to twinning?

Extensive cortical necrosis associated with malformative microgyric-like lesions and with necrotic lesions of the white matter was observed in two male 25 week fetuses. These cases differed from previously reported cases of brain damage in monozygotic twins: both fetuses were affected and the lesions occurred early in pregnancy, before the end of neuronal migration, thus resulting in a cortical malformation associated with destructive lesions.

Adult↗
PubMed1992

Neurological findings and seizure outcome in children with bilateral opercular macrogyric-like changes detected by MRI.

The authors studied 10 patients aged between six and 23 years (mean age 14 years 5 months) with magnetic resonance imaging, which detected bilateral 'macrogyric-like' maldevelopment of the insulo-opercular regions. The data confirm that biopercular gyral anomaly, associated with mental retardation, pseudobulbar palsy (cortical or central) and epilepsy, represents an anatomo-clinical syndrome. Nevertheless, a wide clinical spectrum was found varying from pictures correlating with the topography and extent of the MRI-detected anomaly to conditions indicating wider cerebral involvement. Epilepsy, varying greatly in age at onset and severity, consistently influenced the prognosis for five patients with diffuse EEG abnormalities and intractable seizures with falls. Anterior callosotomy relieved such seizures in one case.

Adolescent↗
PubMed1992

Epilepsy and focal gyral anomalies detected by MRI: electroclinico-morphological correlations and follow-up.

The authors studied 10 patients (mean age 15 years 6 months) with localized developmental gyral disorder detected by MRI. There were two groups of major malformations. Seven patients (group 1) had unilateral 'macrogyric-like' insulo-opercular changes, one of whom died early in life and had extensive microgyria. The six others had mental retardation and epilepsy, three of whom had focal neurological signs. Age at onset of epilepsy varied greatly. Clinical and EEG data suggested a wider cerebral involvement than recognized on MRI. The remaining three patients (group 2) had abnormal gyri of variable topography and extension, with bulging grey matter and ventricular deformity. One had mental retardation, another had neurological signs. All had intractable complex partial seizures and focal EEG anomalies correlating with the MRI lesion site, pointing to a well-defined epileptogenic zone. No clinical or EEG evidence of significant malformation in the remaining brain tissue was observed. Ablative surgery was beneficial for one patient; focal cortical dysplasia was the pathological substrate.

Adolescent↗
PubMed1991

Cerebral lymphoma and HIV encephalitis in a case of paediatric AIDS, with pre-existing multicystic encephalomalacia.

A case of intracerebral malignant B cell lymphoma associated with encephalitis typical of Human Immunodeficiency Virus (HIV) infection is described in a 4 year old child, with post-transfusion Acquired Immune Deficiency Syndrome (AIDS) and severe pre-existing cystic encephalomalacia. This report further documents B cell lymphoma as the commonest cause of an intracerebral mass, and an important cause of death in paediatric AIDS. That more than one pathological process may be responsible for neurological symptoms in paediatric AIDS is also emphasised.

AIDS Dementia Complex↗
PubMed1991

Bilateral porencephalic defect in a newborn after injection of benzol during pregnancy.

Porencephaly is usually considered to be a prenatal brain lesion due to a circulatory failure. We report a case of bilateral porencephaly with heterotopia and absence of the septum pellucidum in a newborn. The mother had received several injections of benzol during pregnancy with an intent of inducing abortion. The possibility of a causal relationship between the administration of benzol and the occurrence of the defect is supported by the existence of previously reported cases of cerebral malformations following maternal exposure to organic solvents.

Abnormalities, Drug-Induced↗
PubMed1991

[Congenital hereditary motor and sensory neuropathy].

The authors report 6 cases of hereditary sensorimotor neuropathy (HSMN) presenting with the following clinical features: (1) severe outcome (3 out of 6 patients died before the age of 4 years), and (2) intellectual impairment (3 out of 6 cases). Histopathological study of nerve biopsies gave heterogeneous results: there was one case of axonal neuropathy (HSMN II of Dyck and Lambert), one case of demyelinating neuropathy with Schwann's cell proliferation (HSMN III of Dyck and Lambert), and one case of giant axonal neuropathy. The last three cases displayed an original pattern hitherto unknown in classical delayed HSMN, with complete disappearance of myelinated sheaths and Schwann's cell proliferation. This particular pattern did not seem to be due to the biopsy being performed at an early stage, since in one case a second biopsy showed the same histological features.

Female↗
PubMed1990

GABAergic mechanisms in the CA3 hippocampal region during early postnatal life.

The developmental pattern of GABAergic neurons in the rat hippocampus during the first week of postnatal life shows several particularities both from a morphological and physiological point of view: (1) GABA immunoreactive neurons which are initially localized in a deep and superficial layer, progressively disappear from these two layers. From the end of the first postnatal week, GABAergic neuronal somata appear throughout the whole hippocampus, but GABA immunoreactive terminal structures are not frequent until the second postnatal week. (2) Intracellular observations in slices reveal the presence in CA3 pyramidal neurons between P0 and P6 (postnatal days) of spontaneous giant depolarizing potentials (GDPs); these are mediated by GABA acting on GABAA receptors and modulated presynaptically by NMDA receptors. During this period of development, GABA and GABAA analogues have a depolarizing action at resting membrane potential. Bicuculline at this developmental stage blocks completely spontaneous and evoked synaptic potentials. During the second postnatal week, when GABA responses shift from depolarizing to hyperpolarizing, bicuculline induces spontaneous interictal discharges. It is suggested that the positive feedback of the GABAergic interneuron on the pyramidal neuron during the first week of life may account for the generation of GDPS which may play an important role in synaptogenesis.

Action Potentials↗
PubMed1990

Kearns-sayre syndrome. Two clinico-pathological cases.

Two clinico-pathological cases of Kearns-Sayre syndrome are reported. In both cases the typical triad (progressive external ophthalmoplegia, heart block, retinitis pigmentosa) was present and spongiosis was the main pathological finding. In one case there was also a marked capillary proliferation, significance of which is discussed. A deletion of the mitochondrial DNA was found in the muscle, spinal cord and brain of this last case.

Adolescent↗