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J Hugon

Publications and source records attributed to J Hugon.

At least 55 records · Page 3Linked to original sources
PubMed1995

[Early diagnosis of Guillain-Barré syndrome by electric stimulations of the nerve roots].

Ulnar nerve electrical stimulations from motor roots to wrist were used in the early Guillain-Barré syndrome (GBS), to improve the electrophysiological diagnosis yield. 22 patients with a GBS were investigated with this technique between 3 to 17 days after the onset. Conventional electrophysiological examination was sufficient to diagnose an Acute Inflammatory Demyelinating Polyneuropathy in 12 cases. In 10 other patients, standard examination remained negative or not conclusive, and vertebral electrical stimulations were decisive for the diagnosis, showing conduction bloks. This method could be routinely performed for an early diagnosis, in association with conventional motor conduction measurements. This study confirms the possibility of a pure proximal demyelinating impairment of the peripheral nervous system in the early GBS.

Adolescent↗
PubMed1994

Glutamate increases tau phosphorylation in primary neuronal cultures from fetal rat cerebral cortex.

Tau proteins are microtubule-associated proteins which promote microtubule polymerisation and stabilization. AT8 is a new monoclonal antibody raised against a phosphorylated Tau protein probably at Serine 202. Tau protein, recognized by AT8 antibody is present in fetal human and rat brains, and in Alzheimer's brains. Here we report that glutamate an excitatory neurotransmitter and also a potent excitotoxin produces in primary neuronal cultures a rapid increase in phosphorylated Tau protein immunoreactivity using AT8 antibody. Glutamate augments neuronal Tau immunoreactivity by 225% using laser confocal immunocytochemistry and by 355% on immunoblot analysis. This experimental model of Tau protein modifications could help to decipher the intracellular biochemical pathways at the origin of phosphorylated Tau protein.

Animals↗
PubMed1994

Neuroprotective effects of riluzole in ALS CSF toxicity.

Amyotrophic lateral sclerosis (ALS) is a neurological disorder neuropathologically characterized by a progressive degeneration of upper and lower motoneurons. The origin of the neuronal death is presently unknown but recent findings suggest that neurodegeneration could be related to an excitotoxic disorder. We have recently shown that the cerebrospinal fluid (CSF) of ALS patients contains for neurones in cultures cytotoxic factors whose toxic properties are mediated by AMPA/kainate receptors, a subgroup of glutamate post-synaptic receptors. This study reports that riluzole partially prevents in vitro the neuronal degeneration produced by ALS CSF (neuronal survival 60.6 +/- 13.1%). Riluzole (5 x 10(-7) M) which reduces excitatory amino acid release, could represent a new pharmacological agent susceptible to be proposed to patients affected by this dramatic neurological disease.

Amyotrophic Lateral Sclerosis↗
PubMed1994

Tetrodotoxin blocks HIV coat protein (gp120) toxicity in primary neuronal cultures.

HIV-1-associated cognitive/motor complex is a frequent neurological complication of the acquired immunodeficiency syndrome (AIDS). The pathogenesis of this syndrome implicates immunopathological and toxic events such as the production of cytokines. The HIV envelope glycoprotein gp120 seems also to play a major role in this process. Gp120 could produce a slow neuronal death probably via the release of neurotoxic factors by CNS macrophages/monocytes. NMDA antagonists and Ca2+ channel blockers in vitro have a powerful neuroprotective effect against gp120 neurotoxicity. The purpose of the present work is to determine whether gp120-induced neurotoxicity is associated with an abnormal neuronal depolarization induced by putative neurotoxins. We have compared in vitro the neuroprotective effects of Tetrodotoxin a Na+ channel blocker, the Ca2+ channel blocker nifedipine and the NMDA antagonist MK-801 in primary cortical neurons taken from embryonic rat and intoxicated with gp120. We observed comparable neuroprotective effects with the 3 precited compounds suggesting that gp120-induced neurotoxic factors act on Na+ channels, NMDA receptors and Ca2+ channels in a cascade of cellular events. We confirmed that the presence of macrophages is needed to trigger a marked gp120-induced neurotoxicity. These results underline the fact that depolarization is an important component of gp120 neurotoxicity in primary neuronal cultures.

Animals↗
PubMed1994

Prevention of HIV coat protein (gp120) toxicity in cortical cell cultures by riluzole.

Neurological complications observed in HIV-infected patients are very frequent. Neocortical lesions include reduced neuronal density due to neuronal degeneration. The HIV envelope protein gp120 has potent neurotoxic properties in cell cultures blocked either by NMDA antagonists or calcium channel antagonists. Moreover, human monocytoid cell lines infected by HIV release endogenous toxic factors with comparable cellular actions. We have analysed the effects of riluzole, a compound reducing the excitatory amino acid release on gp120-induced neurotoxicity in primary neuronal cultures. Riluzole, which blocks the release of glutamate and aspartate from nerve terminals, prevents (10(-7) M) the neuronal degeneration produced by 20 pM of gp120 in cortical cell cultures. This result could suggest that toxic factors produced by activated macrophages might increase glutamate release, and that this may be prevented by riluzole.

Animals↗
PubMed1994

Synaptophysin expression during in vitro neuronal differentiation. An immunocytochemical and a confocal laser microscopic study.

Primary neuronal cultures from mammalian fetal brains are widely used for morphological, biochemical and pharmacotoxicological studies. The usefulness of relatively pure neuronal cultures are now demonstrated for such studies. We have compared the neuronal survival and differentiation, the synaptophysin expression and the glial cell percentage in primary neuronal cultures using two different media: a M1 medium containing 10 % fetal calf serum and a M2 medium supplemented with hormones, ions and chemicals. Our study demonstrates that the M2 medium (a serum-free defined medium) is associated with an increased survival at 14 days of culture, an earlier neuronal differentiation and synaptophysin expression in cell bodies and neurites as it was confirmed by immunocytochemical and confocal laser microscopic studies.

Animals↗
PubMed1993

Cell culture evidence for neuronal degeneration in amyotrophic lateral sclerosis being linked to glutamate AMPA/kainate receptors.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder affecting motor neurons. Glutamate, a potent central-nervous-system toxin, has been proposed as one possible factor in this motoneuron disease. Serum from patients with ALS is known to be toxic when added to neurons in culture. We report on the toxicity to rat neurons in culture of cerebrospinal fluid (CSF) from patients with ALS. CSF were obtained from 10 ALS patients, 10 neurological controls, and 10 other controls. ALS CSF was added at dilutions of 50%, 20%, or 10% and neuron survival was assessed after 24 h. The neuroprotective effects of antagonists to two glutamate receptors were also assessed. ALS CSF was significantly neurotoxic, with a neuronal survival rate of only 47% compared with 80% or so for control CSF. This neurotoxicity was blocked by CNQX, an antagonist to the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA)/kainate receptor but not by two N-methyl-D-aspartate (NMDA) antagonists. ALS CSF contains a specific neurotoxic factor which is AMPA/kainate-like which could have a role in the neuronal degeneration of this disease.

2-Amino-5-phosphonovalerate↗
PubMed1993

Studies of the etiology and pathogenesis of motor neuron diseases. III. Magnetic cortical stimulation in patients with lathyrism.

Neurophysiological assessments of central motor pathways were conducted of 11 Spanish subjects with varying degrees of spastic paraparesis (lathyrism). The disease has been induced more than 40 years ago by subsistance on the neurotixic chick pea Lathyrus sativus. Patient evolution was carried out by magnetic cortical and electric spinal stimulations and recordings of the contralateral muscle responses. Central motor conduction times corresponding to lower limbs were clearly more prolonged in those severely affected patients with marked difficulty walking (Stages 4 and 3). Central conduction times corresponding to upper limbs were delayed in only 1 patient. Taken together with clinical and published neuropathological data, these findings suggest that established lathyrism is essentially a central motor system disorder primarily affecting corticospinal tracts regulating the lower limbs.

Age of Onset↗
PubMed1993

[Antigenic changes of Tau protein induced by glutamate on primary cultures of neurons: immunocytochemistry study].

Degenerating neurons in Alzheimer's disease are characterized by the presence of neurofibrillary tangles constituted by paired helical filaments (PHF). Abnormally phosphorylated Tau protein, a microtubule associated protein is one of the major component of PHF. Abnormal phosphorylation seems to be located in the C-terminal domain but also in the N-terminal region of Tau proteins. Previous studies demonstrated that calcium-mediated glutamate toxicity produces a dose-dependent increase of Tau immunolabellings in neuronal cultures. Biochemical results revealed that these changes could be associated with abnormal Tau migrations on immunoblots. Using three anti-Tau antibodies the present study shows that glutamate toxicity induces in neuronal cultures, Tau modifications localized in the N- and C-terminal domains of the protein. These findings suggest the possibility that glutamate toxicity can induce Tau antigenic changes involving probably the whole molecule.

Animals↗
PubMed1992

Tau antigenic changes induced by glutamate in rat primary culture model: a biochemical approach.

Primary neuronal cultures were treated with glutamate to induce an increase of Tau immunoreactivity similar to that observed in Alzheimer's disease. The Tau profile of neurones in culture before and after exposure to glutamate was analyzed on immunoblots with anti-Tau, anti-paired helical filaments (PHF) and antibody specific for modified Tau. Differences were observed between treated and control cultures: glutamate induced a shift of immunodetection from the lowest to the highest molecular weight Tau isoform and an acidification of Tau proteins. However, these modifications are not exactly those observed in Alzheimer's disease since we were not able to detect 'Alzheimer-type' epitopes on Tau proteins after the glutamate exposure.

Alzheimer Disease↗
PubMed1992

A dose-dependent increase of Tau immunostaining is produced by glutamate toxicity in primary neuronal cultures.

Neuronal degeneration was produced in primary cultures by glutamate exposure and the modifications of Tau immunoreactivity were analysed in degenerating neurons. After 8-12 days of culture, glutamate was applied at different concentrations (50, 100, 200 and 500 mumol) in a Na(+)- and Mg(2+)-free solution containing calcium. Prior to and 12 hours after glutamate exposure cell death was defined by cell counting in each dish. After fixation, neurons were processed for immunocytochemistry using a Tau2 monoclonal antibody and a Tau polyclonal antibody (Sigma). Tau immunostaining was scored by a blind count of immunoreactive cells and a semi-quantitative evaluation. The results show that the number of labelled neurons and the magnitude of neuronal immunolabelling are both related to the glutamate concentration. Our findings indicate that glutamate induces a dose-dependent increase of Tau immunoreactivity directly related to its cellular action on neuronal cells.

Alzheimer Disease↗
PubMed1992

Improvement in motor evoked potentials and clinical course post-steroid therapy in multiple sclerosis.

Motor evoked potentials (MEP) were recorded in 23 patients with definite relapsing multiple sclerosis before and after treatment with a short course of high dose of methylprednisolone. MEP were performed together with clinical examination just before treatment, and 6 and 60 days later. The following results were observed: (1) a statistically significant relationship between the corticospinal deficit and the alteration in MEP, (2) a significant improvement in latency of MEP by day 6, (3) a significant correlation between the change in the Kurtzke disability scale rating and the improvement in MEP. The results provide further evidence for the possible effectiveness of short courses of high dose corticosteroids in the treatment of relapses of multiple sclerosis and the usefulness of MEP in its assessment.

Adult↗
PubMed1992

Adult-onset metachromatic leukodystrophy presenting as isolated peripheral neuropathy.

A 38-year-old man presented with weakness of the lower limbs. Electrophysiology revealed a pronounced demyelinating neuropathy. Nerve biopsy disclosed de- and remyelinating lesions and characteristic lamellar inclusions in Schwann cells and macrophages. There was no familial history of neurologic disorder, and impairment of motor evoked potentials was the only sign of CNS involvement. Arylsulfatase A and cerebroside sulfate sulfatase activities in leukocytes and cultures of the patient's fibroblasts were low. The sulfatide loading test also revealed abnormal sulfatide accumulation. This may be the first reported case of adult metachromatic leukodystrophy presenting as peripheral neuropathy.

Adult↗
PubMed1992

Study of evoked potentials in human African trypanosomiasis.

Human African trypanosomiasis or sleeping sickness has a stage of neurological involvement characterized by the onset of diffuse meningoencephalitis with sleep disturbances and decreased wakefulness. The pathogenesis of this disease is not well understood. We studied auditory, visual, sensory, and motor evoked potentials in 16 patients with trypanosomiasis in the early stage of meningoencephalitis. In all patients, the brain-stem auditory evoked response (BAER) and the pattern-reversal visual evoked response (PVER) were normal. On the other hand, abnormalities of the somatosensory evoked response (SSER) or the motor evoked response (MER) were found in only five cases; however, their relationship to the illness could not be definitely confirmed. The study results indicate that the evaluated pathways were essentially intact, in particular at the level of the brain-stem in the early stage of the disease. Sleep disturbances and decreased wakefulness noted at this stage were thus linked more closely to functional involvement at the level of the sleep centres than to any detectable specific anatomic lesion.

Adolescent↗
PubMed1991

Peripheral and central distal axonopathy of suspected inherited origin in Birman cats.

Three female cats, littermates born from clinically normal parents, were examined at 8 to 10 weeks of age because of a slowly progressive posterior ataxia. Another cat from a previous litter from the same parents suffered from similar neurological symptoms. Histopathological examination of the nervous tissues of these animals revealed degeneration of axons and myelinopathy in a distal distribution pattern. Both peripheral nerves and central nervous system were involved. The central nervous system lesions were most prominent in the lateral pyramidal tracts of the spinal cord, the fasciculi gracili of the dorsal column in the cervical spinal cord and the cerebellar vermian white matter. In the PNS numerous degenerating nerve fibers were found in the sciatic nerves but not in the spinal nerve roots. Our findings show that these cats were suffering from a hereditary multisystem degeneration with a distribution pattern of the lesions suggestive of a distal axonopathy.

Animals↗
PubMed1990

Abnormal distribution of phosphorylated neurofilaments in neuronal degeneration induced by kainic acid.

An abnormal distribution of phosphorylated neurofilaments is present in some human neurodegenerative disorders including Parkinson's disease, Alzheimer's disease, and amyotrophic lateral sclerosis. This study reports the changes of phosphorylated neurofilaments observed in rat spinal cord after intrathecal injection of kainic acid. This receptor agonist of excitatory amino acid produces abnormal phosphorylation of neurofilaments in the cell body and proximal neurites of degenerating neurons. These immunocytochemical modifications observed 2 and 10 days after injections are predominantly located in ventral horn neurons. This study indicates that one of the neuronal responses to excitatory amino acid toxicity is the pathological distribution of phosphorylated neurofilaments in affected neurons. Pathological findings are comparable to those observed in neurodegenerative diseases such as amyotrophic lateral sclerosis.

Animals↗