Update Anti-<Emphasis Type="Italic">N</Emphasis>-Methyl-<Emphasis Type="Italic">D</Emphasis>-Aspartat-Rezeptor-Enzephalitis

Autoimmune encephalitis is a group of autoimmune inflammatory disorders affecting both grey and white matter of the central nervous system. Encephalitis with autoantibodies against the N?methyl-D-aspartate receptor (NMDA-R) is the most frequent autoimmune encephalitis syndrome presenting with a characteristic sequence of psychiatric and neurological symptoms. Treatment necessitates a close interdisciplinary cooperation. This article provides an update on the current knowledge on diagnostic standards, pathogenesis, and treatment strategies for anti-NMDA-R encephalitis from psychiatric and neurological perspectives.     

Mutation analysis of the Ras pathway genes<Emphasis Type="Italic"> NRAS</Emphasis>,<Emphasis Type="Italic"> HRAS</Emphasis>,<Emphasis Type="Italic"> KRAS</Emphasis> and<Emphasis Type="Italic"> BRAF</Emphasis> in glioblastomas

Aberrant activation of Ras signaling is a common finding in human glioblastomas. To determine the contribution of Ras gene mutations to this aberration, we screened 94 glioblastomas for mutations in the three Ras family genes NRAS, KRAS and HRAS. All tumors were additionally analyzed for mutations in BRAF, which encodes a Ras-regulated serine/threonine kinase with oncogenic properties. Mutation analysis of the entire coding regions of NRAS and KRAS, as well as the known mutation hot-spot sites in HRAS, identified somatic point mutations in two glioblastomas, both affecting codon 12 of NRAS (c.35G>A, p.G12D). Three additional tumors carried BRAF mutations altering the known hot-spot codon 599 (c.1796T>A, p.V599E). None of these five glioblastomas showed amplification of the EGFR or PDGFRA genes, while three of the tumors, including two with NRAS and one with BRAF mutation, demonstrated PTEN missense mutations or loss of PTEN mRNA expression. Taken together, our data suggest activating mutations in NRAS or BRAF as a molecular alteration that contributes to aberrant Ras signaling in a small fraction of glioblastomas.     

<Emphasis Type="Italic">c</Emphasis><Emphasis Type="Italic">-MYC</Emphasis> amplification and expression in astrocytic tumors

Point mutations and genomic multiplications in the α-synuclein (αSYN) gene cause autosomal-dominant Parkinson’s disease. Moreover, αSYN fibrils are the major component of Lewy bodies, the neuropathological hallmarks of Parkinson’s disease and dementia with Lewy bodies as well as of glial cytoplasmic inclusions in multiple system atrophy. These diseases are collectively referred to as α-synucleinopathies. Cellular mechanisms regulating αSYN fibril formation and toxicity are intensely studied in vitro, and in cell culture and diverse animal models. Specific neuropathology was achieved in transgenic mouse models using several promoters to express human wild-type and mutant αSYN in brain regions affected by the various α-synucleinopathies. Somatodendritic accumulation of the transgenic αSYN with neuritic distortions was a common finding. The nigrostriatal dopaminergic projections were surprisingly resistant to α-synucleinopathy in transgenic mice, although they tended to be more vulnerable to neurotoxins. In a few mouse models, αSYN aggregated in an age-dependent manner into genuine fibrillar amyloid. Brain region selective αSYN neuropathology correlated with specific behavioral impairments, such as locomotor dysfunction and cognitive decline. Thus, the αSYN fibrillization process is tightly linked to neuropathology. The role and thus therapeutic potential of post-translational modifications (ubiquitinylation, oxidation, phosphorylation, truncation) and modifier genes on αSYN neuropathology can now be assessed in valid transgenic mouse models of α-synucleinopathies.     

Japanese encephalitis can trigger anti-<Emphasis Type="Italic">N</Emphasis>-methyl-<Emphasis Type="SmallCaps">d</Emphasis>-aspartate receptor encephalitis

Japanese encephalitis (JE) is usually a monophasic disease; however, in rare cases, patients with JE may have an early relapse after a partial recovery, giving rise to a biphasic pattern for the disease. In this study, we report three pediatric cases in which post-JE relapse was characterized by movement disorder and/or behavioral problems, and was related to anti-N-methyl-d-aspartate receptor (NMDAR) immunoglobulin G (IgG). Serum and cerebrospinal fluid were examined for anti-NMDAR IgG in three patients who had confirmed JE and then developed relapsing symptoms which were similar to those of anti-NMDAR encephalitis. The main symptoms of the two young children were choreoathetosis, irritability, and sleep disorder; while for the teenager, agitation, mutism, rigidity, and sleep disorder were the main symptoms. Samples of cerebrospinal fluid from all patients were positive for anti-NMDAR IgG, and all patients gradually improved with immunotherapy. Testing for NMDAR antibodies is highly recommend in patients with JE, especially those with a relapsing syndrome involving movement disorder and/or behavioral problems, as these patients may benefit from immunotherapy.     

<Emphasis Type="Italic">Clostridium septicum</Emphasis> Pneumocephalus

Background

Spontaneous pneumocephalus in the nontraumatic setting is distinctly unusual. Pneumocephalus from central nervous system infection with Clostridium septicum has been rarely reported, and more commonly reflects a later stage of abscess formation. We present an unusual case of invasive C. septicum infection without an associated diagnosed malignancy presenting with rapidly progressive CNS pathology and resultant early pneumocephalus.

Methods

Medical records, radiologic imaging, and microbiological specimens of a case were reviewed.

Results

A 66-year-old male presented with a history of two witnessed generalized tonic–clonic seizures on awakening. He was found unresponsive at the scene by paramedics and subsequently intubated. There was no reported antecedent symptomatology, such as headache, fever, chills, focal weakness, and speech or gait disturbances. Medical history was remarkable only for diet-controlled hypertension. Computed tomography (CT) head imaging revealed an abnormal right parietal hypodensity. The patient was evaluated per the acute stroke protocol but was not deemed a candidate for intervention or thrombolytic therapy given the uncertainty of his clinical presentation; intravenous antibiotics were administered for possible sepsis. Follow-up CT imaging of the head performed 8 h later revealed right parieto-temporal pneumocephalus with extensive cerebral edema and effacement of basilar cisterns. Neurosurgical intervention was not deemed appropriate given the catastrophic nature of his injury and the patient subsequently expired 14 h after presentation. Blood cultures grew gram-positive rods in three of four bottles identified as C. septicum.

Conclusions

Clostridium septicum is an uncommon and often fatal cause of nontraumatic pneumocephalus. This underscores the need for a high index of clinical suspicion in cases with unexplained pneumocephalus, as early diagnosis remains the key to survival. In survivors of C. septicum infection, subsequent colonoscopy should be considered to exclude undiagnosed or occult gastrointestinal malignancy.

     

Age-related axonal and myelin changes in the<Emphasis Type="Italic"> rumpshaker</Emphasis> mutation of the<Emphasis Type="Italic"> Plp</Emphasis> gene

The PLP1/Plp gene encodes proteolipid protein (PLP) and DM20, the major central nervous system myelin proteins. Mutations in the PLP1/Plp gene cause dysmyelinating disorders in man and animals. The rumpshaker mutation was first identified in mice and later linked to a family diagnosed with neurological deficits akin to spastic paraplegia. The dysmyelination in the young rumpshaker mouse is well characterised. Here we report evidence for an age-related increase in myelin due mainly to the myelination of small axons, many large axons remain dysmyelinated. Levels of PLP/DM20 and myelin basic protein are considerably greater in myelin fractions from older compared with younger mutants. Myelin in sheaths of larger axons remains poorly compacted and may account for levels of 2,3-cyclic nucleotide 3-phosphodiesterase and myelin-associated glycoprotein being elevated over wild type in older mutant mice. A late-onset distal degeneration of the axons of the longest spinal tract, the fasciculus gracilis, is also noted. This is the first report of Wallerian-type degeneration in mice with spontaneous mutations of the Plp gene.The first two authors contributed equally to the study     

Twenty-three microsatellite loci for <Emphasis Type="Italic">Styrax confusus</Emphasis> and <Emphasis Type="Italic">Styrax japonicus</Emphasis> (Styracaceae)

Twelve microsatellite loci were isolated from an enriched genomic library of the rock scallop (Spondylus calcifer). One locus was monomorphic. Overall polymorphic loci, the mean numbers of alleles per locus at one locality was 9.6 (range 3–16), and the average observed and expected heterozygosities were 0.650 and 0.707, respectively. Three loci deviated from Hardy–Weinberg equilibrium, and from these, one locus had and excess of heterozygotes and the other two loci showed deficits of heterozygotes likely due to the presence of null alleles. No evidence of linkage disequilibrium was found among loci. These loci are the first microsatellites ever reported for the monotypic family Spondylidae, and will be useful to validate the predictions of oceanographic larval transport models and connectivity between patchy reefs within fishing areas and marine reserves in the northern Gulf of California, Mexico.     

The complete mitochondrial genomes of two globally invasive ants,the Argentine ant <Emphasis Type="Italic">Linepithema</Emphasis><Emphasis Type="Italic">humile</Emphasis> and the little fire ant <Emphasis Type="Italic">Wasmannia auropunctata</Emphasis>

Ants are among the most widespread and damaging of invasive alien species. Here, we report the complete mitochondrial genomes for two globally invasive ants: the Argentine ant Linepithema humile and the little fire ant Wasmannia auropunctata. The circular genomes of L. humile and W. auropunctata are 15,929 and 16,362 bp in length, respectively, and encode the same typical set of 37 mitochondrial genes (i.e. 13 PCGs, 22 tRNAs and two rRNAs) and one control region. The mitochondrial genome of W. auropunctata harbors a unique gene arrangement (‘rrnS-trnV-CR-trnM-trnI-trnQ-nad2-trnW-trnC-trnY’; the underlines indicate inverted genes) between rrnL and cox1. Phylogenetic analysis largely corroborated the traditional taxonomy, except for L. humile which was found to be more related to those taxa of the subfamilies Formicinae and Myrmicinae than to the consubfamilial Leptomyrmex pallens. Our genomic data can be readily used for genetic assays of these two globally invasive ants.     

S<Emphasis Type="SmallCaps">pi</Emphasis>C<Emphasis Type="SmallCaps">o</Emphasis>D<Emphasis Type="SmallCaps">yn</Emphasis>: A Toolbox for the Analysis of Neuronal Network Dynamics and Connectivity from Multi-Site Spike Signal Recordings

We implemented an automated and efficient open-source software for the analysis of multi-site neuronal spike signals. The software package, named SpiCoDyn, has been developed as a standalone windows GUI application, using C# programming language with Microsoft Visual Studio based on .NET framework 4.5 development environment. Accepted input data formats are HDF5, level 5 MAT and text files, containing recorded or generated time series spike signals data. SpiCoDyn processes such electrophysiological signals focusing on: spiking and bursting dynamics and functional-effective connectivity analysis. In particular, for inferring network connectivity, a new implementation of the transfer entropy method is presented dealing with multiple time delays (temporal extension) and with multiple binary patterns (high order extension). SpiCoDyn is specifically tailored to process data coming from different Multi-Electrode Arrays setups, guarantying, in those specific cases, automated processing. The optimized implementation of the Delayed Transfer Entropy and the High-Order Transfer Entropy algorithms, allows performing accurate and rapid analysis on multiple spike trains from thousands of electrodes.     

Neurotransmitter Receptor Homologues of <Emphasis Type="Italic">Dictyostelium discoideum</Emphasis>

The social amoeba Dictyostelium discoideum is a genetically amenable eukaryotic cell which displays many animal cell traits and has been used to study cellular signalling for over 30 years. Recently studies have highlighted the roles that molecules associated with synaptic transmission in animals, such as glutamate, GABA and ATP play in cellular differentiation and homeostasis in this simple organism. This short review summarises the evidence for the existence of both ionotropic and metabotropic families of neurotransmitter receptors in Dictyostelium.     

Variations in <Emphasis Type="Italic">Disrupted</Emphasis>-<Emphasis Type="Italic">in</Emphasis>-<Emphasis Type="Italic">Schizophrenia 1</Emphasis> gene modulate long-term longitudinal differences in cortical thickness in patients with a first-episode of psychosis

Schizophrenia patients typically present a widespread bilateral cortical thinning from the early stages of the illness. However, there is controversy whether this reduction in cortical thickness (CT) is static or progressive over the evolution of the disorder. Disrupted-in-Schizophrenia 1 (DISC1) is one of the main candidates genes for schizophrenia, as it has been found associated to the illness, and to several endophenotypes of the disorder including structural brain differences. This gene is known to be involved in neurodevelopment and brain maturation processes. We therefore hypothesized that variations in this gene modulate different progressions of CT in psychosis. Seventy-nine Caucasian drug-naive patients experiencing a first episode of non-affective psychosis were genotyped for rs6675281 (Leu607Phe) and rs821616 (Ser704Cys) SNPs of the DISC1 gene. Brain MRIs were carried out at baseline and 3 years after initiating the treatment. Other clinical and socio-demographic variables were recorded to rule out possible confounding effects. Patients homozygous for the Leu allele of the rs6675281 SNP had a significant (p?<?0.05) descend in CT over the 3-years period, while those carrying the Phe allele presented an increase in CT. When combining the two SNPs we found a synergic effect on CT progression, presenting those patients homozygous for Leu607 +Ser704 a more pronounced cortical thinning. In conclusion, DISC1 gene variations may modulate the longitudinal changes in cortical thickness in patients suffering from a first episode of non-affective psychosis.     

<Emphasis Type="Italic">S</Emphasis>-adenosylmethionine and <Emphasis Type="Italic">S</Emphasis>-adenosylhomocysteine levels in the aging brain of APP/PS1 Alzheimer mice

Hyperhomocysteinemia and factors of homocysteine metabolism, S-adenosylhomocysteine (AdoHcy) and S-adenosylmethionine (AdoMet), may play a role in Alzheimer’s disease (AD). With liquid-chromatography-tandem-mass-spectrometry AdoMet and AdoHcy were determined in brains of 8- and 15-month-old APP/PS1 Alzheimer mice, and their possible roles in AD brains investigated. The finding that AdoMet levels do not differ between the genotypes in (young) 8-month-old mice, but are different in (older) 15-month-old APP/PS1 mice compared to their wild-type littermates, suggests that alterations in AdoMet are a consequence of AD pathology rather than a cause. During aging, AdoMet levels decreased in the brains of wild-type mice, whereas AdoHcy levels diminished in both wild type and APP/PS1 mice. The finding that AdoMet levels in APP/PS1 mice are not decreased during aging (in contrast to wild-type mice), is probably related to less demand due to neurodegeneration. No effect of the omega-3 fatty acid docosahexaenoic acid (DHA) or cholesterol-enriched diets on AdoMet or AdoHcy levels were found.     

Clinical Characteristics and Prognosis of Severe Anti-<Emphasis Type="Italic">N</Emphasis>-methyl-<Emphasis Type="SmallCaps">d</Emphasis>-aspartate Receptor Encephalitis Patients

Background and purpose

Data concerning the characteristics and duration of the critical manifestations, treatment response, and long-term outcomes of severe anti-N-methyl-d-aspartate receptor (anti-NMDAR) encephalitis patients compared to those of non-severe patients are limited. This observational study was performed to explore the clinical characteristics and long-term outcomes of severe anti-NMDAR encephalitis patients.

Methods

According to their characteristics on admission to the neurology intensive care unit, patients with anti-NMDAR encephalitis were divided into a severe group and a non-severe group. The demographics, clinical manifestations, main accessory examinations, immunotherapy, and outcomes of patients were recorded. Statistical analyses were employed to examine the differences in each observed indicator between the severe and non-severe groups.

Results

This study enrolled 111 patients with anti-NMDAR encephalitis, including 59 males and 52 females with a mean age of 27.7?±?13.7 years; 39 (35.1%) patients were in the severe group, and 72 (64.9%) patients were in the non-severe group. Compared to the non-severe group, the severe group exhibited a higher proportion of epilepsy, involuntary movement, disturbance of consciousness, autonomic dysfunction, and central hypoventilation. The cerebrospinal fluid (CSF) of all patients was positive for the NMDAR antibody, but only 57 patients (51.4%) tested positive for the NMDAR antibody in the blood. The proportion of patients with a strong positive NMDAR antibody titer in the severe group (48.7%) was higher than that in the non-severe group (29.2%). The proportion of patients receiving intravenous gamma immunoglobulin in the severe group was higher than that in the non-severe group (P?=?0.003), and only patients in the severe group received plasma exchange, intravenous rituximab, and cyclophosphamide treatment. No significant difference was observed in the prognosis between the severe group and the non-severe group after 6 months and during long-term follow-up.

Conclusion

Most severe anti-NMDAR encephalitis patients will eventually achieve good long-term prognoses after receiving early, positive and unremitting combined immunotherapy and life support.