Transforming growth factor alpha expression as a response of murine motor neurons to axonal injury and mutation-induced degeneration.

We previously showed that degenerating adult motor neurons of the murine mutant wobbler, a model of spinal muscular atrophy, express Transforming Growth Factor alpha (TGF alpha), a growth factor endowed with glio- and neurotrophic activities. Here, we evaluated whether TGF alpha expression is a general response of adult motor neurons to injury. Synthesis of its precursor (pro-TGF alpha) was investigated in another model of motoneuronal degeneration, the murine mutant muscle deficient, and in hypoglossal motor neurons following axonal crush and cut. In control conditions, motor neurons were devoid of pro-TGF alpha immunoreactivity. In the mutant lumbar spinal cord, pro-TGF alpha immunoreactive motor neurons appeared as soon as the disease developed and pro-TGF alpha expression persisted until the latest stages of degeneration. Motor neurons and astrocytes of the white matter weakly immunoreactive for the TGF alpha receptor were also present in both control and mutant lumbar spinal cords. Following hypoglossal nerve crush and cut, motoneuronal pro-TGF alpha expression was precocious and transient, visible at one day post-injury and lasting for only 3 days, during which time astrocyte-like cells immunoreactive for both TGF alpha and its receptor appeared within the injured nucleus. Enhanced TGF alpha mRNA levels following nerve crush showed that activation occurred at the transcriptional level. These results show that upregulation of TGF alpha is an early and common response of adult murine motor neurons to injury, regardless of its experimental or genetic origin.

Contralateral disappearance of parkinsonian signs after subthalamic hematoma.

A man with Parkinson's disease (PD) suddenly developed a left hemiballismus, and the CT showed a hematoma of the right subthalamic nucleus. After the ballistic movements had disappeared, akinesia and the other parkinsonian signs did not reappear on the left. This clinical case confirms the involvement of the subthalamic nucleus in the akinesia of PD, as suggested by recent experimental data.

Long-term histological follow-up of genetically modified myoblasts grafted into the brain.

Although primary muscle cells have been used as intracerebral vehicles for transgene expression in the past, data concerning their long-term survival after grafting into the brain, and the reaction of the host tissue to their implantation are lacking. In order to study these aspects, we have implanted, into the brain, primary muscle cells infected ex vivo with recombinant retroviruses carrying the E. coli LacZ gene. The muscle cells were delivered stereotaxically into different areas of the brain of adult rats and the grafts were analyzed up to 105 days after implantation. Intraventricular implantations did not lead to surviving grafts. In contrast, myoblasts developed when they were grafted into gray or white matter regions. They appeared numerous during the first weeks, but decreased dramatically in number over time. Over months, the grafts appeared to fill up with collagen. Astrocytes elaborated a continuous glia limitans surrounding the implant. Blood vessels coming from the host tissue were found within the grafts. The blood-brain barrier was permanently disrupted within the transplants. beta-Galactosidase activity was abundant during the first weeks, but decreased to a very low level subsequently. This decrease paralleled that of the number of muscle cells. In conclusion, myoblasts transplanted into the adult brain survived only temporarily, which implies a transient transgene expression. In addition, before being eliminated, muscle cells were surrounded by a glia limitans, which may limit exchanges with the host tissue. Altogether, these results suggest that intracerebral transplantation of myoblasts may possibly provide a relevant vehicle only for short-term delivery of a gene product.

In vivo transfer of a marker gene to study motoneuronal development.

Adenovirus vectors containing a marker gene (lacZ from Escherichia coli) are potent for transferring the gene to neurones after intraparenchymal injections. Expression of the marker gene may lead to the synthesis of an enormous amount of beta-galactosidase which diffuses throughout the entire neurone, providing a 'Golgi-like' staining. This suggested that the technique may be used to study the morphology of specific neuronal populations. We have validated this hypothesis by analysing the postnatal development of motoneurones in the rat cervical cord. Injections of the viral suspension into one ventral horn were performed at different ages after birth. Histochemical staining using X-Gal revealed morphological changes occurring within the first 3 weeks with enlargement of the perikaryon and increased dendritic complexity. Immunoreactivity for CGRP was visualized in double-staining experiments. In vivo transfer of a marker gene therefore provides a new way to analyse neuronal morphology which allows selection of the cells to be studied and double-labelling with immunohistochemical markers.

Adenovirus-mediated gene transfer to the brain: methodological assessment.

The purpose of this short review is to analyse major advantages and limitations of the adenovirus (Ad), specifically with relevance to its use as a vector for gene transfer to the brain. The characteristics of Ad transduction include: the relative absence of cell type specificity; the limited spatial spread of the virus; and the long-term expression of the transgene. In the central nervous system, in contrast to that which occurs in other organs, Ad transduction in the adult does not systematically provoke cell death. Nevertheless, a proportion of the transduced cells do die, and this represents a conspicuous problem. Mechanisms leading to cell death in the brain may include immune rejection and inflammation-related toxicity, although this would not explain all of the results, and direct toxicity related to either inappropriate preparation or the transduction itself. Taking into account uncertainties concerning the innocuousness of Ad transduction, it may seem unwise to envisage Ad gene therapy for diseases that are not life-threatening and/or benefit from adequate drug or surgical treatments (e.g. Parkinson's disease or epilepsy). Ad vectors may not be easily used either in diseases displaying major immune dysfunction (e.g. multiple sclerosis). In contrast, malignant brain tumors and numerous neurodegenerative diseases (such as Huntington's, Alzheimer's diseases or amyotrophic lateral sclerosis) are directly life-threatening and deprived of any adequate treatment. They may be appropriate targets for Ad-mediated gene therapy, once both the vector and the gene of interest have been defined and optimized.

Induction of D2 dopamine receptor mRNA synthesis in a 6-hydroxydopamine parkinsonian rat model.

By injecting 6-hydroxydopamine into the pars compacta of the substantia nigra, we produced a hemiparkinsonian rat model in which there is almost complete destruction of the dopaminergic nigrostriatal pathway but sparing of the dopaminergic mesolimbic system. The lesion has been characterized by several criteria: a rotational behavior in response to apomorphine, a complete loss of tyrosine hydroxylase immunoreactivity in the lesioned substantia nigra, a near total depletion of dopamine and metabolites in the striatum ipsilateral to the lesion, and a supersensitivity of the dopamine D2 receptors in the ipsilateral striatum. Dopaminergic striatal deafferentation was accompanied by an increase of D2 receptor mRNA synthesis in the striatum ipsilateral to the lesion, suggesting that the increased D2 receptor density observed after the lesion is due to an increase of the synthesis of receptor molecules. This synthesis appears to be regulated at the transcriptional level.

Hot-water epilepsy in an adult: ictal EEG, MRI and SPECT features.

Reflex epilepsy constitutes a rare form of epileptic seizures. We observed a 20-year-old man who presented with seizures induced by immersion in hot water. The trigger stimulus was specific. Contrast CT scan and MRI were all normal, not revealing any structural lesion. Ictal EEG recorded during a hot bath showed focal epileptic discharges in the left temporo-occipital area. Interictal SPECT showed a hypometabolism in the same cerebral region. Neuroimaging studies were rarely performed in this uncommon type of epilepsy. Nevertheless, in our case the result of the SPECT suggests a localized functional disturbance in the emergence of the disorder.

Hypertrophic neuropathy of the facial nerve.

Hypertrophic neuropathy is a peripheral nerve lesion that is histologically characterized by onion bulb formations around axons. This histologic picture, which is usually seen in generalized hypertrophic neuropathies, can occasionally be observed in single nerves as localized hypertrophic neuropathy. Cranial involvement of such localized hypertrophic neuropathy represents a very rare entity; only a few cases have been reported in the literature. We report the history of a progressive facial paralysis with a tumorous enlargement of the seventh cranial nerve that was clinically suspected of being a schwannoma. Pathological examination permitted the diagnosis of hypertrophic neuropathy.

[Arachnoid cyst of the temporal fossa. Subdural hematoma. Contribution of MRI]. / Kyste arachnoïdien de la fosse temporale. Hématome sous-dural. Apport de l'IRM.

A 20-year old man presented with an arachnoid cyst of the middle fossa and a subdural hematoma (SDH). An intra-cystic hemorrhage masked the presence of the SDH on CT. MRI demonstrated a communication between cyst and SDH. The mechanism of SDH formation is discussed.

[Meningioma with pseudo-vascular disclosure]. / Les méningiomes à révélation pseudo-vasculaire.

In a retrospective study of 125 case reports of intracranial supratentorial meningiomas, the authors have isolated 10 patients whose meningioma had been revealed by pseudo-vascular syndromes. Mean age and sex ratio were the same in this group of patients as in those patients whose meningioma had been more classically disclosed by an epileptic seizure, a motor or a progressive sensorimotor deficit. The site of the tumour exerted an influence on the nature of clinical manifestations. There was no correlation between the size of the tumour and the transient or prolonged course of the pseudo-vascular syndrome. The pathogenesis of these disorders is discussed.

[Beta-2 microglobulin in cerebrospinal fluid in neurology]. / La beta 2-microglobuline du liquide céphalorachidien en neurologie.

OBJECTIVES: beta 2-microglobulin (beta 2-m) is a small molecular weight protein (11 800 Daltons) which can transudate into the cerebrospinal fluid (CSF) in the same manner than albumin. Intrathecal synthesis is a sign of local immuno-stimulation and is correlated with immunoglobulin G. The aim of this study was to ascertain the relationship between beta 2-microglobulin levels in the CSF and neurological diseases. METHODS: beta 2-microglobulin was assayed in the CSF and blood using an immunoenzyme method in 64 patients with multiple sclerosis (n = 14), human immunodeficiency virus (HIV) infection (n = 5), meningitis (n = 12) or a peripheral neurological disease (n = 10) and in 7 control subjects. RESULTS: There was no overall correlation between beta 2-m in the CSF and blood levels (r = 0.35). In controls, beta 2-m CSF and blood levels were respectively 0.94 +/- 0.22 and 1.46 +/- 0.83 mg/l. beta 2-m was significantly higher in the CSF of patients with meningitis and in the HIV positive patients (4 +/- 3.5 and 3.69 +/- 2.06 mg/l respectively) (p < 0.05). Type of meningitis (bacterial or non-bacterial) had no effect on the CSF level. For the HIV patients, the CSF/blood ratio for beta 2-m was similar to that in controls due to a rise in both blood and CSF. Finally, in patients with multiple sclerosis, there was no significant change in CSF level of beta 2-m. CONCLUSION: beta 2-microglobulin in cerebrospinal fluid was not found to be correlated with the neurological diseases studied and cannot be used as a diagnostic test.

Cerebral infarction in young people. A study of 148 patients with early cerebral angiography.

The aetiology of strokes was studied in a hospital based series of patients aged up to 40 years with precise clinical and radiological criteria. One hundred and forty five patients (75 males and 73 females) aged five to 40 years with cerebral ischaemia were evaluated. Aetiology was heterogeneous and could be classified into seven groups. Cerebral arteriograms were performed in all cases and indicated the aetiological diagnosis in most patients. Embolism was the most frequent recognised abnormality (38.4%). There were no complications of arteriography. Arterial dissections discovered by arteriography were the cause of the stroke in 10.1% of the patients. Atherosclerosis was diagnosed in 32 cases and was the commonest cause (21.6%). In one fifth of cases no cause was found. Contraceptive drugs were considered as potential cause of ischaemic stroke in 11.5%, cardiac diseases in 12.8% and haematological disorders in 8.1%. Other potential causes included migraine, inflammatory diseases, pregnancy and lacunas. Follow up in 126 cases showed that many patients had good functional recovery.

Stimulation of the cyclic GMP pathway by NO induces expression of the immediate early genes c-fos and junB in PC12 cells.

Stimulation of several second messenger pathways induces the expression of immediate early genes such as c-fos, c-jun, junB, and junD, but little is known about their induction via the stimulation of the cyclic GMP pathway. Here we looked at the expression of early genes in pheochromocytoma PC12 cells after activation of cytosolic guanylate cyclase by sodium nitroprusside. This compound spontaneously releases NO, a molecule known to be involved in cell communication. We found that expression of c-fos and junB but not of c-jun or junD is increased upon activation of cyclic GMP pathway. c-fos mRNA expression was the most activated (fourfold at 30 min), whereas junB response was more modest (2.2-fold activation at 60 min). Nuclear extracts of stimulated cells show increased binding capacity to the AP1 binding site consistent with the dose-response curve. The activating effect of nitroprusside could be reproduced by dipyridamole, a selective cyclic GMP phosphodiesterase inhibitor and by 8-p-chlorophenylthio-cyclic GMP, a permeant selective cyclic GMP-dependent protein kinase activator, and abolished by KT5823, an inhibitor of that kinase. The results show that NO promotes early gene activation and AP1 binding enhancement through the stimulation of the cyclic GMP pathway.