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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.

Assessment programs recently designed to follow-up patients with Huntington's disease (HD) in therapeutic trials have not included electrophysiological testing in the list of mandatory examinations. This omission is likely due to the current lack of data establishing a clear correlation between the electrophysiological results and those of clinical assessment. We address this issue in a cohort of 36 patients at relatively early stages of the disease (I and II). Electrophysiological studies comprised the recording of palmar sympathetic skin responses (SSRs), blink reflexes (BRs), thenar long latency reflexes (LLRs), cortical somatosensory evoked potentials (SEPs), and electromyographic silent periods evoked by transcranial magnetic stimulation (SPs). Results were analyzed with reference to disease duration and staging and to specific cognitive, psychiatric, and motor alteration. SEPs were the most and very sensitive markers, because they were abnormal in 94% of patients. Except for LLRs, alteration of electrophysiological results increased in parallel to the evolution of the disease. Except for LLRs and SSR latency, electrophysiological results correlated with those of specific clinical examinations. In particular, an increased BR latency or a reduced amplitude of the N20 component of SEPs correlated with the extent of bradykinesia, whereas a reduced amplitude of SSRs or of the N30 component of SEPs correlated with hyperkinesia. Overall, electrophysiological tests, in particular SEPs and BRs, appeared sensitive and interesting in the follow-up of HD patients and correlated with various clinical parameters, suggesting that these easy to perform and noninvasive repeatable examinations could be added fruitfully to the assessment programs for HD.

Diffuse invasion of the brain by tumor cells is a hallmark of human glioblastomas and a major cause for the poor prognosis of these tumors. This phenomenon is only partially reproduced by rodent models of gliomas that display a very high rate of proliferation and limited cell migration. We have analyzed the development of human glioblastoma cells (GL15) xenografted into the brain of immunosuppressed rats, in order to define the characteristics of tumor cell invasion. As identified by the specific immunolabeling of the tumor cells for the human HLA-ABC antigen, GL15 tumors reproduced the three types of intraparenchymal invasion observed in patients. First, a majority of multipolar tumor cells intermingled rapidly and profusely with host neural cells in the margin of the injection site. This progressively enlarging area was principally responsible for the tumor growth over time. Second, in the gray matter, columns of thin bipolar tumor cells aligned along capillary walls. Third, in the white matter, elongated bipolar isolated tumor cells were observed scattered between axonal fibers. The maximum migration distances along white matter fibers remained significantly higher than the maximum migration distances along blood vessels, up to two months after injection. Development of the tumor was associated with a significant increase of vascularization in the area of tumor spread. Xenografting of human GL15 glioblastoma cells into the immunosuppressed rat brain allowed to differentiate between the three classical types of invasion identified in the clinic, to quantify precisely the distances of migration, and to evaluate cell morphology for each of these routes. The present results support the existence of host/tumor cells interactions with specific characteristics for each type of invasion.

Summary Background Huntington's disease is a neurodegenerative disease of genetic origin that mainly affects the striatum. It has severe motor and cognitive consequences and, up to now, no treatment. Motor and cognitive functions can be restored in experimental animal models by means of intrastriatal transplantation of fetal striatal neuroblasts. We explored whether grafts of human fetal striatal tissue could survive and have detectable effects in five patients with mild to moderate Huntington's disease. Methods After 2 years of preoperative assessment, patients were grafted with human fetal neuroblasts into the right striatum then, after a year, the left striatum. Final results were assessed 1 year later on the basis of neurological, neuropsychological, neurophysiological, and psychiatric tests. The results obtained were compared with those of a cohort of 22 untreated patients at similar stages of the disease who were followed up in parallel. Repeated magnetic resonance imaging (MRI) and positron emission tomography (PET) scanning with fluorine-18-labelled fluorodeoxyglucose was also done to assess metabolic activity. Findings The final PET-scan assessment showed increased metabolic activity in various subnuclei of the striatum in three of five patients, contrasting with the progressive decline recorded in the two other patients in the series, as seen in patients with untreated Huntington's disease. Small areas of even higher metabolic activity, coregistering with spherical hyposignals on MRI were also present in the same three patients, suggesting that grafts were functional. Accordingly, motor and cognitive functions were improved or maintained within the normal range, and functional benefits were seen in daily-life activities in these three patients, but not in the other two. Interpretation Fetal neural allografts could be associated with functional, motor, and cognitive improvements in patients with Huntington's disease.

This study describes issues related to the safety and tolerability of fetal striatal neural allografts as assessed in five patients with Huntington's disease. Huntington's disease (HD) is characterized by motor, cognitive, and behavioral disturbances. The latter include psychological disturbances and, as a consequence, we took particular care to analyze behavioral changes, in addition to the usual "safety" follow-up. We conducted multidisciplinary follow-up at least 2 years before and 1 year after grafting. Psychological care extended to close relatives. The grafting procedure itself was altogether safe and uneventful, and there were no apparent clinical deleterious effects for 1 year. The immunosuppressive treatment, however, was complicated by various problems (irregular compliance, errors of handling, side effects). Direct psychological consequences of the transplantation procedure were rare and not worrisome, although mood alteration requiring treatment was observed in one patient. Indirectly, however, the procedure required patients and relatives to accept constraints that tended to complicate familial situations already marred by aggressivity and depression. All patients and close relatives expressed major expectations, in spite of our strong and repeated cautioning. It is clearly important to be aware of these particular conditions since they may eventually translate into psychological difficulties in coping with the long-term clinical outcome of the procedure, if not beneficial. Despite an overall good tolerance, therefore, this follow-up calls for caution regarding the involvement of HD patients in experimental surgical protocols.

Synthesis of the ciliary neurotrophic factor (CNTF) and its specific receptor (CNTFRα) is widespread in the intact CNS, but potential biological roles for this system remain elusive. Contradictory results have been obtained concerning a possible effect on the morphological and biochemical phenotype of astrocytes. To reassess this question, we have taken advantage of adenovirus-mediated gene transfer into the rat brain to obtain the local release of CNTF. Stereotaxic administration of CNTF recombinant adenovirus vectors into the striatum led to phenotypic changes in astrocytes located in regions that were related axonally to striatal neurons at the injection site. Astrocytes appeared hypertrophied and displayed an increase in both GFAP and CNTF immunoreactivity. This response was observed up to 5 weeks after injection, the longest time studied. It was not observed after the administration of a control vector. The methodology used in the present study, allowing us to analyze the effect of the factor in areas remote from the injection site, has provided conclusive evidence that CNTF affects the astroglial phenotype in the intact CNS. The characteristics of these effects may explain why contradictory results have been obtained previously, because this signaling system seems to have a low efficiency and therefore requires a high local concentration of the factor close to the target cells. One might speculate as to the involvement of a CNTF astroglio–astroglial signaling system in the organized response of a population of astrocytes to changes in CNS homeostasis detected locally, even by a single cell.

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. β-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.

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.

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.

We examined a 29-year-old woman who had language disturbances and memory impairment after a left thalamic infarction. MRI showed injury that was limited to the tuberothalamic artery territory. Beside reduced voice volume and verbal memory trouble, she presented with aspontaneity, loss of psychic self-activation and affective drive. Considering thalamic lesions, this loss of psychic self-activation or 'athymhormie' was found in a left thalamic infarct and could not be considered as an exclusive characteristic of bithalamic infarctions. The disappearance of the neurobehavioral disturbances within 15 days after the onset of the troubles was associated with the decreasing of the mass lesion found by MRI.

International audience; Ciliary neurotrophic factor (CNTF) is a potent protective factor for striatal neurons in animal models of Huntington's disease (HD). Clinical application of this potential therapeutic still requires the design and optimization of delivery systems. In the case of HD, spatial spread in the vast volume occupied by the striatum and long-term delivery of the factor are particular challenges for these systems. We explored the potential of adenovirus-mediated gene transfer to fulfill these requirements by studying the functional and anatomical effects of single-site striatal delivery of CNTF recombinant vectors in a rat model of HD. In an initial series of experiments, unilateral injections of CNTF adenovirus were performed in rats 10, 30, or 90 d before a 5 d neurotoxic treatment with systemic 3-nitropropionic acid (3NP). Preservation of striatal neurons was observed at all time points, demonstrating temporally extended neuroprotective effects of the CNTF adenovirus. In a second series of experiments , bilateral injections of CNTF adenovirus were performed in the medial aspect of the striatum 10 d before starting 3NP intoxication. Despite placement of the CNTF-producing vector outside the lateral striatal area susceptible to lesion, massive protection of corticostriatopallidal circuits was observed, associated with significant behavioral benefits. This spatial spread of neuroprotection is discussed with reference to the retrograde transport of the adenovirus vector and the anterograde transport of the transgenic CNTF. Overall, adenovirus-mediated CNTF gene transfer appears to be a potentially useful delivery system for widespread, long-term circuit neuroprotection in HD patients.

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.

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.

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.