Functional Recovery in Autoimmune Encephalitis: A Prospective Observational Study

Background

Prospective observations of functional recovery are lacking in patients with autoimmune encephalitis defined by antibodies against synaptic proteins and neuronal cell surface receptors.

Methods

Adult patients with a diagnosis of autoimmune encephalitis were included into a prospective registry. At 3, 6 and 12 months of follow-up, the patients’ modified Rankin Scale (mRS) was obtained.

Results

Patients were stratified into three groups according to their antibody (Ab) status: anti-NMDAR-Ab (n=12; group I), anti-LGI1/CASPR2-Ab (n=35; group II), and other antibodies (n=24; group III). A comparably higher proportion of patients in group I received plasma exchange/immunoadsorption and second line immunosuppressive treatments at baseline. A higher proportion of patients in group II presented with seizures. Group III mainly included patients with anti-GABA_BR-, anti-GAD65- and anti-GlyR-Ab. At baseline, one third of them had cancer. Patients in groups I and III had much higher median mRS scores at 3 months compared to patients in group II. A median mRS of 1 was found at all follow-up time points in group II.

Conclusions

The different dynamics in the recovery of patients with certain autoimmune encephalitides have important implications for clinical trials. The high proportion of patients with significant disability at 3 months after diagnosis in groups I and III points to the need for improving treatment options. More distinct scores rather than the mRS are necessary to differentiate potential neurological improvements in patients with anti-LGI1-/CASPR2-encephalitis.

Genotype-guided diagnostic reassessment after exome sequencing in neuromuscular disorders: experiences with a two-step approach

Background and purpose

Next‐generation sequencing has greatly improved the diagnostic success rates for genetic neuromuscular disorders (NMDs). Nevertheless, most patients still remain undiagnosed, and there is a need to maximize the diagnostic yield.

Methods

A retrospective study was conducted on 72 patients with NMDs who underwent exome sequencing (ES), partly followed by genotype‐guided diagnostic reassessment and secondary investigations. The diagnostic yields that would have been achieved by appropriately chosen narrow and comprehensive gene panels were also analysed.

Results

The initial diagnostic yield of ES was 30.6% (n = 22/72 patients). In an additional 15.3% of patients (n = 11/72) ES results were of unknown clinical significance. After genotype‐guided diagnostic reassessment and complementary investigations, the yield was increased to 37.5% (n = 27/72). Compared to ES, targeted gene panels (<25 kilobases) reached a diagnostic yield of 22.2% (n = 16/72), whereas comprehensive gene panels achieved 34.7% (n = 25/72).

Conclusion

Exome sequencing allows the detection of pathogenic variants missed by (narrowly) targeted gene panel approaches. Diagnostic reassessment after genetic testing further enhances the diagnostic outcomes for NMDs.

Management of Autoimmune Encephalitis: An Observational Monocentric Study of 38 Patients

Over the last years the clinical picture of autoimmune encephalitis has gained importance in neurology. The broad field of symptoms and syndromes poses a great challenge in diagnosis for clinicians. Early diagnosis and the initiation of the appropriate treatment is the most relevant step in the management of the patients. Over the last years advances in neuroimmunology have elucidated pathophysiological basis and improved treatment concepts. In this monocentric study we compare demographics, diagnostics, treatment options and outcomes with knowledge from literature. We present 38 patients suffering from autoimmune encephalitis. Antibodies were detected against NMDAR and LGI1 in seven patients, against GAD in 6 patients) one patient had coexisting antibodies against GABA_A and GABA_B), against CASPR2, IGLON5, YO, Glycine in 3 patients, against Ma-2 in 2 patients, against CV2 and AMPAR in 1 patient; two patients were diagnosed with hashimoto encephalitis with antibodies against TPO/TG. First, we compare baseline data of patients who were consecutively diagnosed with autoimmune encephalitis from a retrospective view. Further, we discuss when to stop immunosuppressive therapy since how long treatment should be performed after clinical stabilization or an acute relapse is still a matter of debate. Our experiences are comparable with data from literature. However, in contrary to other experts in the field we stop treatment and monitor patients very closely after tumor removal and after rehabilitation from first attack.

Psychoses in epilepsy: A comparison of postictal and interictal psychoses

We retrospectively analyzed data of patients with epilepsy (n=1434) evaluated with prolonged EEG monitoring in order to estimate the prevalence of postictal psychosis (PP) and interictal psychosis (IP), to investigate a potential association of psychosis subtype with epilepsy type, and to assess differences between PP and IP. The overall prevalence of psychosis was 5.9% (N=85); prevalence of PP (N=53) and IP (N=32) was 3.7% and 2.2%, respectively. Of patients with psychosis, 97.6% had localization-related epilepsy (LRE). Prevalence of psychosis was highest (9.3%) in patients with temporal lobe epilepsy (TLE). When comparing PP with IP groups on demographic, clinical, and psychopathological variables, patients with IP were younger at occurrence of first psychosis (P=0.048), had a shorter interval between epilepsy onset and first psychosis (P=0.002), and more frequently exhibited schizophreniform traits (conceptual disorganization: P=0.008; negative symptoms: P=0.017) than those with PP. Postictal psychosis was significantly associated with a temporal seizure onset on ictal EEG (P=0.000) and a higher incidence of violent behavior during psychosis (P=0.047). To conclude, our results support the presumption of a preponderance of LRE in patients with psychosis and that of a specific association of TLE with psychosis, in particular with PP. Given the significant differences between groups, PP and IP may represent distinct clinical entities potentially with a different neurobiological background.

The effect of early prednisolone treatment on the generalization rate in ocular myasthenia gravis

BACKGROUND AND PURPOSE

Several small retrospective studies have observed that patients with a purely ocular manifestation of myasthenia gravis (MG) are significantly less likely to convert to a generalized disease when treated early on with corticosteroids. However, given the limited number of reported patients in the literature these findings still remain controversial.

METHODS

In order to increase the number of published cases, we performed a retrospective analysis on 44 patients with newly diagnosed ocular MG who were subsequently either treated with corticosteroids or received no immunosuppressive therapy at all. The generalization rate was assessed at the end of a 2-year follow-up period.

RESULTS

Whereas none of 17 treated patients generalized, 11 of 27 (41%) untreated patients developed generalized symptoms. The difference between the groups was significant (P=0.003).

CONCLUSIONS

Our results agree well with previous studies on this issue. Taken together, published data indicate risk ratios for generalization of below 0.32 under corticosteroid treatment in comparison to untreated patients.

Novel SCARB2 mutation in action myoclonus-renal failure syndrome and evaluation of SCARB2 mutations in isolated AMRF features

BACKGROUND

Action myoclonus-renal failure syndrome is a hereditary form of progressive myoclonus epilepsy associated with renal failure. It is considered to be an autosomal-recessive disease related to loss-of-function mutations in SCARB2. We studied a German AMRF family, additionally showing signs of demyelinating polyneuropathy and dilated cardiomyopathy. To test the hypothesis whether isolated appearance of individual AMRF syndrome features could be related to heterozygote SCARB2 mutations, we screened for SCARB2 mutations in unrelated patients showing isolated AMRF features.

METHODS

In the AMRF family all exons of SCARB2 were analyzed by Sanger sequencing. The mutation screening of unrelated patients with isolated AMRF features affected by either epilepsy (n = 103, progressive myoclonus epilepsy or generalized epilepsy), demyelinating polyneuropathy (n = 103), renal failure (n = 192) or dilated cardiomyopathy (n = 85) was performed as high resolution melting curve analysis of the SCARB2 exons.

RESULTS

A novel homozygous 1 bp deletion (c.111delC) in SCARB2 was found by sequencing three affected homozygous siblings of the affected family. A heterozygous sister showed generalized seizures and reduction of nerve conduction velocity in her legs. No mutations were found in the epilepsy, renal failure or dilated cardiomyopathy samples. In the polyneuropathy sample two individuals with demyelinating disease were found to be carriers of a SCARB2 frameshift mutation (c.666delCCTTA).

CONCLUSIONS

Our findings indicate that demyelinating polyneuropathy and dilated cardiomyopathy are part of the action myoclonus-renal failure syndrome. Moreover, they raise the possibility that in rare cases heterozygous SCARB2 mutations may be associated with PNP features.

Analysis of four prevalent filaggrin mutations (R501X, 2282del4, R2447X and S3247X) in Austrian and German patients with atopic dermatitis

BACKGROUND

Recently, mutations in the filaggrin gene (FLG) have been shown to be a major predisposing factor for atopic dermatitis (AD).

OBJECTIVE

In this study, we evaluated the influence of four prevalent mutations (R501X, 2282del4, R2447X and S3247X) in a large cohort of 462 Austrian and German AD patients and in 402 control individuals.

RESULTS

We found a strong association of the FLG mutations with AD. Subgroup analysis revealed a significantly higher proportion of patients with an early age of disease onset and significantly higher median serum IgE levels among mutation carriers. Furthermore, we observed an overrepresentation of null alleles in AD patients with concomitant asthma compared with those without this co-morbidity.

CONCLUSION

Our data confirm and extend the knowledge of the influence of FLG mutations in AD.

Analysis of the prodynorphin promoter polymorphism in atopic dermatitis and disease-related pruritus

Pruritus is one of the key symptoms in atopic dermatitis (AD). The prodynorphin polypeptide is a precursor protein of pruritus-modulating opioid peptides. It is encoded by the prodynorphin gene (PDYN). To investigate a possible correlation of PDYN promoter polymorphisms with intensity of pruritus in patients with AD, we genotyped 211 Austrian patients with AD and 197 nonatopic controls. No significant association of the PDYN promoter polymorphism with AD in general was found when patients with AD were compared with controls. The analysis of possible associations with pruritus intensity also showed no relevant difference in the allelic distribution between patients with different pruritus-score values. These data argue against an important role of the PDYN promoter polymorphism in AD in general and in the development of disease-related pruritus, although owing to our small sample size, a weak effect cannot be excluded. Additional studies are needed to further evaluate the influence of PDYN polymorphism in pruritus.

A novel mutation in the VCP gene (G157R) in a German family with inclusion-body myopathy with Paget disease of bone and frontotemporal dementia

Mutations in the valosin-containing protein (VCP) are known to cause autosomal-dominant inclusion-body myopathy with Paget's disease of bone and frontotemporal dementia (IBMPFD). We report a novel missense mutation (G157R) in the N-terminal region of the VCP gene in a German family. Family members presented with mild to moderate proximal muscle weakness, Paget disease of bone, and signs of early cognitive decline, with onset in the fourth decade. Two family members also showed signs of early hearing impairment, which was confirmed to be sensorineural in one person, a symptom not yet described in the context of IBMPFD.

Report of the Task Force on pre-graduate education in Europe of the education committee of the European Federation of Neurological Societies Composition of the task force of the education committee on pre-graduate education

BACKGROUND AND PURPOSE

The demographical evolution and the technological revolution seen in the last decades, in developed countries, have dramatically changed the practice of Neurology. However, the academic curriculum in many medical schools has not been updated accordingly over many of the European Countries. The Education Committee of the European Federation of Neurological Societies (EFNS) implemented in 2000 a Task Force on pre-graduate education trying to give guidelines to adequate pre-graduate education to the present status.

METHODS AND DISCUSSION

Based on the results of two questionnaires, the first sent to the delegates of the EFNS and to the delegates of the European Board of Neurology, and the second answered by the Task Force members themselves, this paper describes the Task Force recommendations aimed to improve Neurology Education in the Medical Schools. These recommendations are also discussed with the analyses of the current bibliography available.

Pharmacoresistance in epilepsy: a pilot PET study with the P-glycoprotein substrate R-[(11)C]verapamil

PURPOSE AND METHODS

Regional overexpression of the multidrug transporter P-glycoprotein (P-gp) in epileptic brain tissue may lower target site concentrations of antiepileptic drugs and thus contribute to pharmacoresistance in epilepsy. We used the P-gp substrate R-[(11)C]verapamil and positron emission tomography (PET) to test for differences in P-gp activity between epileptogenic and nonepileptogenic brain regions of patients with drug-resistant unilateral temporal lobe epilepsy (n = 7). We compared R-[(11)C]verapamil kinetics in homologous brain volumes of interest (VOIs) located ipsilateral and contralateral to the seizure focus.

RESULTS

Among different VOIs, radioactivity was highest in the choroid plexus. The hippocampal VOI could not be used for data analysis because it was contaminated by spill-in of radioactivity from the adjacent choroid plexus. In several other temporal lobe regions that are known to be involved in seizure generation and propagation ipsilateral influx rate constants K(1) and efflux rate constants k(2) of R-[(11)C]verapamil were descriptively increased as compared to the contralateral side. Parameter asymmetries were most prominent in parahippocampal and ambient gyrus (K(1), range: -3.8% to +22.3%; k(2), range: -2.3% to +43.9%), amygdala (K(1), range: -20.6% to +31.3%; k(2), range: -18.0% to +38.9%), medial anterior temporal lobe (K(1), range: -8.3% to +14.5%; k(2), range: -14.5% to +31.0%) and lateral anterior temporal lobe (K(1), range: -20.7% to +16.8%; k(2), range: -24.4% to +22.6%). In contrast to temporal lobe VOIs, asymmetries were minimal in a region presumably not involved in epileptogenesis located outside the temporal lobe (superior parietal gyrus, K(1), range: -3.7% to +4.5%; k(2), range: -4.2% to +5.8%). In 5 of 7 patients, ipsilateral efflux (k(2)) increases were more pronounced than ipsilateral influx (K(1)) increases, which resulted in ipsilateral reductions (10%-26%) of R-[(11)C]verapamil distribution volumes (DV). However, for none of the examined brain regions, any of the differences in K(1), k(2) and DV between the epileptogenic and the nonepileptogenic hemisphere reached statistical significance (p > 0.05, Wilcoxon matched pairs test).

CONCLUSIONS

Even though we failed to detect statistically significant differences in R-[(11)C]verapamil model parameters between epileptogenic and nonepileptogenic brain regions, it cannot be excluded from our pilot data in a small sample size of patients that regionally enhanced P-gp activity might contribute to drug resistance in some patients with temporal lobe epilepsy.

The stigma of mental illness: anticipation and attitudes among patients with epileptic, dissociative or somatoform pain disorder

The aim of this study was to survey the attitudes of 101 consecutive in- and out-patients with epileptic, dissociative or somatoform pain disorders (mean age: 43 [+/-11] years; 58% female) from either the Department of Psychiatry or Neurology toward anticipated mental illness stigma. The patients were administered a modified 12-item version of Links Stigma Questionnaire. Nearly 60% of all 101 patients believe that "most people" would not allow a mental patient "to take care of their children", "most young women" would be "reluctant to date a man" who has been treated for a mental illness and "most employers would pass over" the application of a psychiatric patient in favour of another applicant. Fifty five percent of the respondents assume that "most people think less of a person who has been in a mental hospital" and over a half of all patients interviewed assert that the general population thinks that psychiatric patients are "less intelligent, less trustworthy and that their opinion is taken less seriously by others". Gender, age and education had no influence on the overall results. There is a high stigmatisation concerning psychiatry even in patients with epilepsy and somatoform/dissociative symptoms with psychiatric comorbidity. Fear of being stigmatized is more pronounced among somatoform pain patients as compared to patients suffering from epileptic or dissocative disorders, with particular reference to close personal relationships.

Idiopathic generalized epilepsy phenotypes associated with different EFHC1 mutations

We sequenced 61 patients with various idiopathic generalized epilepsy (IGE) syndromes for mutations in the EFHC1 gene. We detected three novel heterozygous missense mutations (I174V, C259Y, A394S) and one possibly pathogenic variant in the 3' UTR (2014t>c). The mutation I174V was also detected in 1 of 372 screened patients with temporal lobe epilepsy. We conclude that mutations in the EFHC1 gene may underlie different types of epilepsy syndromes.

Andreas Rett and benign familial neonatal convulsions revisited

In 1964 Andreas Rett published the first account of a family with benign familial neonatal convulsions (BFNC). The authors retraced Rett's family and report that the clinical and genetic features of this original family fit the currently accepted definitions of BFNC. They also consider the career of Dr. Rett, a researcher and social reformer as well as an advocate for the rights of children with developmental disabilities.

Mutations in the CLCN2 gene are a rare cause of idiopathic generalized epilepsy syndromes

Mutations in the chloride channel gene CLCN2 have been reported in families with generalized and focal epilepsy syndromes. To evaluate the contribution of mutations in the CLCN2 gene to the etiology of epilepsies in our population, we screened 96 patients with different epilepsy syndromes and a putative genetic background. No definite mutations were found in our study population. We conclude that mutations in the CLCN2 gene are only a rare cause of idiopathic generalized epilepsy.

Inclusion body myopathy and Paget disease is linked to a novel mutation in the VCP gene

Mutations in the valosin-containing protein (VCP) on chromosome 9p13-p12 were recently found to be associated with hereditary inclusion body myopathy, Paget disease of the bone, and frontotemporal dementia (IBMPFD). We identified a novel missense mutation in the VCP gene (R159H; 688G>A) segregating with this disease in an Austrian family of four affected siblings, who exhibited progressive proximal myopathy and Paget disease of the bone but without clinical signs of dementia.

Association of an ABCB1 gene haplotype with pharmacoresistance in temporal lobe epilepsy

The multidrug transporter P-glycoprotein is suspected of contributing to pharmacoresistance in temporal lobe epilepsy (TLE). To assess the role of functional variations in its coding gene (ABCB1) the authors genotyped 210 patients with TLE who were stratified according to their degree of drug resistance. They identified a common haplotype that when present in the homozygous state significantly increased the risk for pharmacoresistance.

Vestibular processing in human paramedian precuneus as shown by electrical cortical stimulation

The authors describe a 16-year-old patient with recurrent episodes of epileptic linear self-motion perception and occasional body tilts. Intracranial seizure monitoring located the seizure onset, caused by a circumscribed ependymoma, in the right paramedian precuneus. Electrical cortical stimulation of this area could reproduce the same vestibular sensations, which ceased after lesionectomy. The findings implicate the paramedian area of the precuneus in the processing of static and dynamic vestibular, probably otolithic, information.

Altered expression of voltage-dependent calcium channel alpha(1) subunits in temporal lobe epilepsy with Ammon's horn sclerosis

Voltage-dependent calcium channels, the initial components in the calcium signalling cascade, are increasingly being recognised as relevant factors in the pathology of epilepsy. To further characterise their role in temporal lobe epilepsy associated with Ammon's horn sclerosis, we investigated the immunohistochemical distribution of five different voltage-dependent calcium channel alpha(1) subunits (alpha(1A), alpha(1B), alpha(1C), alpha(1D), alpha(1E)) in 14 hippocampal specimens of patients with Ammon's horn sclerosis in comparison with eight autopsy control cases. In epilepsy specimens an increased immunoreactivity was observed for alpha(1A), alpha(1B), alpha(1D) and alpha(1E) in the neuropil of the dentate gyrus molecular layer. Dentate gyrus granule cells and residual CA3 pyramidal neurones showed enhanced immunoreactivity for alpha(1A), while labelling of these neurones was decreased for alpha(1C). Astrocytes in Ammon's horn sclerosis specimens were strongly immunoreactive for the alpha(1C) subunit contrasting with an absent astrocytic alpha(1C) labelling in controls. Our results suggest that the expression of calcium channels in neurones and glial cells is dynamically regulated in temporal lobe epilepsy, supporting the relevance of calcium signalling pathways for this disease.

Buffering intracellular calcium disrupts motoneuron development in intact zebrafish embryos

Numerous studies, performed mainly on dissociated cells, have shown that calcium signals have a role during different stages of neuronal development. However, the actions of calcium during neuronal development in vivo remain to be established. The present study has investigated the role of intracellular calcium signals during development of motoneurons in the spinal cord of intact zebrafish embryos. Loading blastomeres of early embryos with either the calcium buffer BAPTA or the calcium reporter dye Calcium Green, was shown to disrupt motoneuron development in the spinal cord of embryos at 24 h postfertilisation. Loading the calcium buffer BAPTA, at an intracellular concentration of 1 mM, into the blastomeres of early embryos did not alter the resting levels of intracellular calcium, but significantly dampened transient rises in intracellular calcium in the cells of later stage embryos. Loading cells with 1 mM BAPTA significantly decreased the number of motoneurons present in the spinal cord at 24 h, indicating that calcium signals are important for normal motoneuron differentiation. Furthermore, in those BAPTA-filled cells that did adopt a motoneuron cell fate, axogenesis was found to be inhibited, suggestive of a role for calcium signalling in neurite initiation. This work provides evidence that calcium signals are necessary at several stages of motoneuron development in vivo.

Distribution of a calcium channel subunit in dystrophic axons in multiple sclerosis and experimental autoimmune encephalomyelitis

Multiple sclerosis and experimental autoimmune encephalomyelitis (EAE) are immune-mediated diseases of the CNS. They are characterized by widespread inflammation, demyelination and a variable degree of axonal loss. Recent magnetic resonance spectroscopy studies have indicated that axonal damage and loss are a reliable correlate of permanent clinical disability. Accordingly, neuropathological studies have confirmed the presence and timing of axonal injury in multiple sclerosis lesions. The mechanisms of axonal degeneration, however, are unclear. Since calcium influx may mediate axonal damage, we have studied the distribution of the pore-forming subunit of neuronal (N)-type voltage-gated calcium channels in the lesions of multiple sclerosis and EAE. We found that alpha(1B), the pore-forming subunit of N-type calcium channels, was accumulated within axons and axonal spheroids of actively demyelinating lesions. The axonal staining pattern of alpha(1B) was comparable with that of beta-amyloid precursor protein, which is an early and sensitive marker for disturbance of axonal transport. Importantly, within these injured axons, alpha(1B) was not only accumulated, but also integrated in the axoplasmic membrane, as shown by immune electron microscopy on the EAE material. This ectopic distribution of calcium channels in the axonal membrane may result in increased calcium influx, contributing to axonal degeneration, possibly via the activation of neutral proteases. Our data suggest that calcium influx through voltage-dependent calcium channels is one possible candidate mechanism for axonal degeneration in inflammatory demyelinating disorders.

An autosomal dominant early adult-onset distal muscular dystrophy

In this study we describe an autosomal dominant distal muscular dystrophy in a small Austrian family. The myopathy started in early adulthood with a slowly progressive weakness of the muscles of the anterior tibial compartment, followed by the long finger extensors and sternocleidomastoids in some family members. Other muscles were spared. Histopathology showed fiber size variation and autophagic vacuoles. This disease pattern is similar to Laing distal myopathy, which has been described previously in only one other family.

Real-time measurements of calcium dynamics in neurons developing in situ within zebrafish embryos

We have developed a non-invasive technique to measure intracellular calcium ([Ca2+]i) in neurons growing within intact embryos of the zebrafish (Danio rerio). A single blastomere was injected with a calcium-sensitive fluorescent dye (Calcium Green dextran) between the 32- and 128-cell stage and the embryo imaged between 16 h and 20 h postfertilisation using laser scanning confocal microscopy. Labelled nerve cells from embryos preinjected with dye and dissociated at 16 h showed a fluorescence increase (66+/-22%; n=11) in response to depolarisation with KCl confirming that the dye remained intracellular and was sensitive to calcium. In addition, fluorescence changes in activated muscle cells of intact embryos showed that the dye was capable of responding to [Ca2+]i changes in vivo. Imaging of dye loaded cells over 30-min periods in embryos between 16 and 20 h revealed that the majority of neurons within the brain and spinal cord did not show spontaneous fluorescence changes distinguishable from noise. However, a subset of neurons within the ventral spinal cord exhibited spontaneous, repetitive [Ca2+]i oscillations which may have a functional significance during neuronal development.

Calcium channels in neuroblastoma cell growth cones

The concentration of free calcium ions in the cytosol has been shown to influence many components of growth cone behaviour, including the extension of filopodia and veils, the addition of new membrane to the plasmalemma, the retraction and disappearance of filopodia, and gross collapse and retraction of the growth cone. A spatially localized modulation of these processes by very local calcium changes has been proposed to underlie the steering of growth cones by gradients of neurotransmitters, voltage and cell adhesion molecules. Such local control can be studied in mouse neuroblastoma cells, where depolarization causes calcium to rise in a limited number of spatially restricted hotspots, triggering a localized advance. We have studied the simple, club-shaped growth cones that are characteristically found on advancing neurites. Depolarization caused calcium to increase most at the distal, leading tip. Agents that disrupt calcium-induced calcium release do not affect growth cone calcium dynamics, ruling out a local release of calcium at the tip as a cause of the gradient. Using cell-attached patch recording, we find that L-type calcium channels are present at a higher density at the distal tip than in the proximal growth cone. Our results show that the calcium gradients seen in depolarized growth cones are a direct consequence of a gradient of calcium channel density.

Nuclear calmodulin responds rapidly to calcium influx at the plasmalemma

We have studied the rate and extent of calcium binding to calmodulin in neuronal cytosol and nucleus during brief calcium influx across the plasmalemma. Rat sensory neurones were whole-cell patch clamped using a pipette containing a fluorescent analogue of calmodulin that reports when it has bound calcium. Cytosolic and nuclear signals were separated using a confocal microscope. Plasmalemmal calcium influx during a one second depolarization that activated L type calcium channels caused large fractions of calmodulin in both the cytosol and nucleus to bind calcium. Thus, contrary to previous predictions, nuclear processes that require the calcium:calmodulin complex will be activated readily by even brief cell stimulation.

Biphasic effect of calcium on neurite outgrowth in neuroblastoma and cerebellar granule cells

We have examined the effect of cytosolic calcium concentration ([Ca2+]i) on neurite outgrowth in two neuronal cells, cerebellar granule cells and N1E-115 neuroblastoma cells. The set point [Ca2+]i in unstimulated cells bathed in normal extracellular medium was 37 nM and 108 nM, respectively. When we altered extracellular calcium concentration to cause small excursions of [Ca2+]i either above or below the set point, neurite outgrowth from granule cells declined. Thus granule cells show the bell-shaped dependence of neurite outgrowth on [Ca2+]i characteristic of sensory and other neurones [Dev. Brain Res., 70 (1992) 287-290; The Axon, Oxford University Press, New York, 1994]. In contrast, neurite outgrowth from N1E-115 cells increased monotonically as [Ca2+]i was reduced. This result, which is consistent with results obtained by studying individual growth cones [J. Neurosci., 9 (1989) 4007-4020], implies that these transformed cells are aberrant in having no bell-shaped dependence of neurite outgrowth on [Ca2+]i. In both cell types an increase of [Ca2+]i above the set point reduced neurite outgrowth. However, this decline did not persist as [Ca2+]i was set to increasingly high levels by increasing extracellular calcium. Rather, in both cell types, an increase of extracellular calcium above 6.9 mM produced a second, increasing phase of neurite outgrowth.

The demyelinating potential of antibodies to myelin oligodendrocyte glycoprotein is related to their ability to fix complement

A panel of 13 monoclonal antibodies (mAbs) has been raised to the central nervous system-specific glycoprotein, myelin oligodendrocyte glycoprotein; five of these mAbs recognize a carbohydrate epitope on the molecule. Although all of the mAbs recognized surface epitopes on cultured oligodendrocytes and stained central nervous system tissue sections in a similar manner, marked differences were seen in their ability to induce demyelination in experimental allergic encephalomyelitis in the Lewis rat. This variation in pathogenic potential was not related to the specificity of a given mAb for carbohydrate or peptide epitopes of myelin oligodendrocyte glycoprotein, but correlated with its ability to fix complement.

Coronavirus induced primary demyelination: indications for the involvement of a humoral immune response

Coronavirus MHV-JHM infection of rodents can result in demyelinating encephalomyelitis. We analysed histological changes induced by coronavirus MHV-JHM infection in Lewis rats. Besides an acute disease (AE), chronic panencephalitis (CPE) and subacute demyelinating encephalomyelitis (SDE) were induced. These disease types were differentiated by the incubation period, the localization of lesions, the type of tissue damage and distribution of virus antigen. In AE and CPE, virus antigen was detected in neurons, astrocytes and oligodendrocytes, whereas in SDE neurons lacked virus antigen. Viral nucleocapsid protein (N) was present in the cytoplasm and the spike protein (S) was displayed on the surface of infected neural cells. However, expression of S protein relative to N protein was severely impaired in SDE lesions. Quantitative analysis of infiltrating inflammatory cells revealed that the number of macrophages and T cells were similar in lesions of AE, CPE and SDE. In contrast to that, SDE lesions contained a significantly higher number of IgG + B cells and plasma cells. In addition active demyelinating SDE lesions displayed an enhanced IgG content and deposits of complement C9. These results indicate that virus induced primary demyelination could be a consequence of antibody mediated cytotoxicity. Furthermore, a reduction in the number of cells producing spike protein in the chronic forms of the disease indicates down-regulation of this protein, possibly mediated by anti-S antibodies.

Nucleocapsid or spike protein-specific CD4+ T lymphocytes protect against coronavirus-induced encephalomyelitis in the absence of CD8+ T cells

To investigate the antiviral CD4+ T cell response in coronavirus MHV-JHM-induced encephalomyelitis, spleen and thymic lymphocytes from diseased rats were stimulated in culture with virus Ag, expanded and tested for their specificity to viral proteins and nucleocapsid (N) and spike (S) proteins that had been expressed in bacteria. A strong T cell response specific for N was measurable during acute disease, whereas S-specific T cells were only detectable in rats with a later onset of disease. CD4+ T cell lines with specificity for virus and either N or S protein were established and their influence on the course of a mouse hepatitis virus-JHM infection was investigated. All lines were of the CD4+ phenotype. Both N and S protein-specific CD4+ T cells conferred protection to infected Lewis rats and reduced the amount of infectious virus in the central nervous system. After transfer of CD4+ T cells and challenge with virus, an increase in the antiviral IgM response occurred, but neutralizing antibodies were not detectable during the period of virus clearance. Previous CD8+ cell depletion did not abrogate protection mediated by CD4+ T cell line transfer.

Nucleocapsid or spike protein-specific CD4+ T lymphocytes protect against coronavirus-induced encephalomyelitis in the absence of CD8+ T cells

To investigate the antiviral CD4+ T cell response in coronavirus MHV-JHM-induced encephalomyelitis, spleen and thymic lymphocytes from diseased rats were stimulated in culture with virus Ag, expanded and tested for their specificity to viral proteins and nucleocapsid (N) and spike (S) proteins that had been expressed in bacteria. A strong T cell response specific for N was measurable during acute disease, whereas S-specific T cells were only detectable in rats with a later onset of disease. CD4+ T cell lines with specificity for virus and either N or S protein were established and their influence on the course of a mouse hepatitis virus-JHM infection was investigated. All lines were of the CD4+ phenotype. Both N and S protein-specific CD4+ T cells conferred protection to infected Lewis rats and reduced the amount of infectious virus in the central nervous system. After transfer of CD4+ T cells and challenge with virus, an increase in the antiviral IgM response occurred, but neutralizing antibodies were not detectable during the period of virus clearance. Previous CD8+ cell depletion did not abrogate protection mediated by CD4+ T cell line transfer.

Immunohistochemical localization of the alpha 1, alpha 2 and alpha 3 subunit of the GABAA receptor in the rat brain

The immunohistochemical distribution of the alpha 1, alpha 2 and alpha 3 subunit of the gamma-aminobutyric acid-A (GABAA) receptor was investigated in the rat brain using affinity-purified antibodies against unique parts of the amino acid sequence of the respective subunits. The distribution of the 3 subunits differed markedly from each other indicating heterogeneity of the GABAA-receptor composition in different brain regions and at various receptive compartments (dendrites or somata) of neuronal cells.

Microglial cells are a component of the perivascular glia limitans

The ultrastructural relation between microglial cells and cerebral blood vessels was studied in rat brains by immune electron microscopy using antibodies against the common leukocyte antigen (Ox1), the complement receptor 3 (Ox42), and against class I and class II histocompatibility antigens (MHC antigens; Ox3, Ox6, Ox18, and I1-69). Microglial cell processes were found incorporated between the astrocytic foot processes of the glia limitans in 4-13% of cerebral microvessels. After intravenous injection of gamma-interferon, either alone or in combination with tumor necrosis factor, these microglial cell processes expressed classes I and II MHC antigens. Studies in (Lewis X DA)F1-DA bone marrow chimeras demonstrated that these cell processes belonged to resident microglia. This study suggests that microglial cells may play an important role in antigen recognition at the blood-brain barrier.

Expression of adhesion molecules and histocompatibility antigens at the blood-brain barrier

The migration of inflammatory cells through the blood-brain barrier in health and disease involves complex interactions between hematogenous cells, endothelial cells, the basement membrane and the perivascular glia limitans. Recent evidence is presented, suggesting that part of these interactions involve antigen independent mechanisms, mediated by cellular adhesion molecules. The accessibility of endothelial adhesion molecules in the intact blood-brain barrier is lower compared to vessels in other organs. This may account for the low traffic of hematogenous cells through the normal blood-brain barrier. However, in inflammatory conditions the expression of endothelial adhesion molecules is upregulated, which may lead to recruitment of inflammatory cells into the lesions. Antigen specific activation of T-cells at the blood-brain barrier apparently takes place mainly at perivascular monocytes and microglia cells. In severe inflammatory lesions, however, astrocytes may be additionally involved in antigen presentation.