ApoE and Aβ1–42 interactions

Abnormalities in the processing of amyloid precursor protein to amyloid-β (Aβ) are causal factors, and the presence of the ε4 allele of apolipoprotein E (apoE) is the primary risk factor for Alzheimer’s disease (AD). Based, at least in part, on these genetics, the potential structural and functional interactions between these two proteins are the focus of our research. To understand the nature of the physical interactions between apoE and Aβ, we initially utilized gel-shift assays to demonstrate that native apoE2 and E3 (associated with lipid particles) form an SDS-stable complex with Aβ that is more abundant than the apoE4:Aβ complex. We further demonstrated that exogenous apoE3 but not E4 prevents Aβ-induced neurotoxicity by a process that requires apoE receptors. In addition, both exogenous apoE3 and E4 prevent Aβ-induced, glial-mediated inflammation, also via a process that requires apoE receptors. These functional effects all occur at a molar ratio of apoE to Aβ of 1:30. Because the biological activities for both apoE and Aβ are profoundly influenced by their isoform and conformation, respectively, we further investigated the idea that apoE3 and E4 differentially interact with particular aggregation species of Aβ1–42. Our overall hypothesis is that apoE has two general functions in relation to Aβ. First, apoE interacts with oligomeric Aβ via an apoE receptor-mediated process to inhibit neurotoxicity and neuroinflammation (apoE3>apoE4) a process possibly related to binding and clearance of apoE3:oligomer complexes. Second, apoE facilitates the deposition of Aβ as amyloid (apoE4 \s>apoE3). We will continue to investigate the effect of apoE isoform and Aβ conformation on the structural and functional interactions between these two proteins in relation to the pathogenesis of AD.     

Dynamic expression of Slit1–3 and Robo1–2 in the mouse peripheral nervous system after injury

The Slit family of axon guidance cues act as repulsive molecules for precise axon pathfinding and neuronal migration during nervous system development through interactions with specific Robo receptors.Although we previously reported that Slit1–3 and their receptors Robo1 and Robo2 are highly expressed in the adult mouse peripheral nervous system,how this expression changes after injury has not been well studied.Herein,we constructed a peripheral nerve injury mouse model by transecting the right sciatic nerve.At 14 days after injury,quantitative real-time polymerase chain reaction was used to detect mRNA expression of Slit1–3 and Robo1–2 in L4–5 spinal cord and dorsal root ganglia,as well as the sciatic nerve.Immunohistochemical analysis was performed to examine Slit1–3,Robo1–2,neurofilament heavy chain,F4/80,and vimentin in L4–5 spinal cord,L4 dorsal root ganglia,and the sciatic nerve.Co-expression of Slit1–3 and Robo1–2 in L4 dorsal root ganglia was detected by in situ hybridization.In addition,Slit1–3 and Robo1–2 protein expression in L4–5 spinal cord,L4 dorsal root ganglia,and sciatic nerve were detected by western blot assay.The results showed no significant changes of Slit1–3 or Robo1–2 mRNA expression in the spinal cord within 14 days after injury.In the dorsal root ganglion,Slit1–3 and Robo1–2 mRNA expression were initially downregulated within 4 days after injury;however,Robo1–2 mRNA expression returned to the control level,while Slit1–3 mRNA expression remained upregulated during regeneration from 4–14 days after injury.In the sciatic nerve,Slit1–3 and their receptors Robo1–2 were all expressed in the proximal nerve stump;however,Slit1,Slit2,and Robo2 were barely detectable in the nerve bridge and distal nerve stump within 14 days after injury.Slit3 was highly ex-pressed in macrophages surrounding the nerve bridge and slightly downregulated in the distal nerve stump within 14 days after injury.Robo1 was upregulated in vimentin-positive cells and migrating Schwann cells inside the nerve bridge.Robo1 was also upregulated in Schwann cells of the distal nerve stump within 14 days after injury.Our findings indicate that Slit3 is the major ligand expressed in the nerve bridge and distal nerve stump during peripheral nerve regeneration,and Slit3/Robo signaling could play a key role in peripheral nerve repair after injury.This study was approved by Plymouth University Animal Welfare Ethical Review Board (approval No.30/3203) on April 12,2014.     

Protective effect of zinc on amyloid-ß 25–35 and 1–40 mediated toxicity

Amyloid beta-peptide (Abeta) is widely held to be associated with Alzheimer's disease, the insoluble aggregates of the peptide being the major constituents of senile plaques. In this study, we evaluated the effect of Zn(2+) (5, 50 and 200 microM) on Abeta induced toxicity using the human teratocarcinome (NT2) cell line. Our results proved that 50 and 200 microM Zn(2+) protected NT2 cells from Abeta 25-35 toxicity. Zinc was also shown to be effective by preventing the loss of mitochondrial membrane potential (DeltaPsi(m)) induced by Abeta 25-35, not allowing cytochrome c release from mitochondria, and subsequently, caspase 3 activation. However, when the cells were treated with Abeta 1-40, only Zn(2+) 5 microM had a protective effect. We have further observed that 5 microM Zn(2+) prevented Abeta 1-40 aggregation into a beta-sheet structure. Considering the results presented, we argue that Zn(2+) has a concentration-dependent protective effect.     

Rufinamide efficacy and safety in children aged 1–4 years with Lennox–Gastaut syndrome

Purpose

The treatment options for Lennox–Gastaut syndrome (LGS), a pediatric epileptic syndrome, are limited, especially in younger children. Rufinamide tablets were safe and effective as an add-on treatment in Korean children and adolescents <20?years of age with LGS. This subgroup analysis aimed to evaluate the efficacy and safety of rufinamide tablets in LGS pediatric patients aged 1–4?years.

Opsoclonus–myoclonus–ataxia syndrome and HIV seroconversion

Journal of Neurology -     

A new POLG1 mutation with peo and severe axonal and demyelinating sensory–motor neuropathy

Background Progressive external ophthalmoplegia (PEO) is a mitochondrial disorder associated with defective enzymatic activities of oxidative phosphorylation (OXPHOS), depletion of mitochondrial DNA (mtDNA) and/or accumulation of mtDNA mutations and deletions. Recent positional cloning studies have linked the disease to four different chromosomal loci. Mutations in POLG1 are a frequent cause of this disorder. Methods We describe two first–cousins: the propositus presented with PEO,mitochondrial myopathy and neuropathy, whereas his cousin showed a Charcot– Marie–Tooth phenotype. Neurophysiological studies, peroneal muscle and sural nerve biopsies, and molecular studies of mtDNA maintenance genes (ANT1, Twinkle, POLG1, TP) and non dominant CMT–related genes (GDAP1, LMNA, GJB1) were performed. Results A severe axonal degeneration was found in both patients whereas hypomyelination was observed only in the patient with PEO whose muscle biopsy specimen also showed defective OXPHOS and multiple mtDNA deletions. While no pathogenetic mutations in GDAP1, LMNA, and GJB1 were found, we identified a novel homozygous POLG1 mutation (G763R) in the PEO patient. The mutation was heterozygous in his healthy relatives and in his affected cousin. Conclusions A homozygous POLG1 mutation might explain PEO with mitochondrial abnormalities in skeletal muscle in our propositus, and it might have aggravated his axonal and hypomyelinating sensory–motor neuropathy. Most likely, his cousin had an axonal polyneuropathy with CMT phenotype of still unknown etiology.     

Alpha-chemokine receptors CXCR1–3 and their ligands in idiopathic inflammatory myopathies

The idiopathic inflammatory myopathies (IIM) are a heterogeneous group of neuromuscular disorders subdivided into polymyositis (PM), sporadic inclusion body myositis (sIBM) and dermatomyositis (DM). Chemokines play an essential role in sustained inflammation associated with IIM. We studied the distribution of the -chemokine receptors CXCR1, 2, 3 and their ligands interferon- (IFN-)-inducible T cell chemoattractant (I-TAC), IFN--inducible protein of 10 kDa (IP-10), monokine induced by IFN- (MIG) and growth-related oncogene (GRO) in IIM using immunohistochemistry, immunofluorescence and Western blotting. Abundant expression of IP-10 was observed on macrophages and T cells surrounding and invading non-necrotic muscle fibers in PM and sIBM and in T cells in perimysial infiltrates of DM. IP-10 was also localized to blood vessel endothelial cells in all inflammatory and normal muscle tissues. The distribution of other -chemokines was variable: Only low levels of MIG and I-TAC were detected; GRO was localized to the endomysial infiltrates of some PM and sIBM samples, but not in DM. Muscle tissues were invariably CXCR1 negative, while a subset of inflammatory cells in all IIM were CXCR2 positive. Strong CXCR3 expression was observed on the majority of T cells in each IIM. We describe the differential repertoire of -chemokines in IIM, and offer additional proof of the predominance of Th1-driven reactions in the immunopathogenesis of all three diagnostic subgroups. We suggest the Th1-mediated immunity in general, and the CXCR3/IP-10 interaction in particular, as potential targets for novel therapeutic intervention in IIM.     

Abnormal premotor–motor interaction in heterozygous Parkin- and Pink1 mutation carriers

Objectives

Mutations in the Parkin and PINK1 gene account for the majority of autosomal recessive early-onset Parkinson cases. There is increasing evidence that clinically asymptomatic subjects with single heterozygous mutations have a latent nigrostriatal dopaminergic deficit and could be taken as in vivo model of pre-symptomatic phase of Parkinsonism.

Neuron-specific Sumo1–3 knockdown in mice impairs episodic and fear memories

Background

Growing evidence suggests that small ubiquitin-like modifier (SUMO) conjugation plays a key role in brain plasticity by modulating activity-dependent synaptic transmission. However, these observations are based largely on cell culture experiments. We hypothesized that episodic and fear memories would be affected by silencing SUMO1–3 expression.

Methods

To investigate the role of SUMO conjugation in neuronal functioning in vivo, we generated a novel Sumo transgenic mouse model in which a Thy1 promoter drives expression of 3 distinct microRNAs to silence Sumo1–3 expression, specifically in neurons. Wild-type and Sumo1–3 knockdown mice were subjected to a battery of behavioural tests to elucidate whether Sumoylation is involved in episodic and emotional memory.

Results

Expression of Sumo1–3 microRNAs and the corresponding silencing of Sumo expression were particularly pronounced in hippocampal, amygdala and layer V cerebral cortex neurons. The Sumo knockdown mice displayed anxiety-like responses and were impaired in episodic memory processes, contextual and cued fear conditioning and fear-potentiated startle.

Limitations

Since expression of Sumo1–3 was silenced in this mouse model, we need to verify in future studies which of the SUMO paralogues play the pivotal role in episodic and emotional memory.

Conclusion

Our results indicate that a functional SUMO conjugation pathway is essential for emotionality and cognition. This novel Sumo knockdown mouse model and the technology used in generating this mutant may help to reveal novel mechanisms that underlie a variety of neuropsychiatric conditions associated with anxiety and impairment of episodic and emotional memory.     

Genotype–phenotype correlation and frequency of distribution in a cohort of Chinese Charcot–Marie–Tooth patients associated with GDAP1 mutations

Journal of Neurology - Mutations in ganglioside-induced differentiation-associated-protein 1 (GDAP1) have been associated with both subtypes of Charcot–Marie–Tooth (CMT) disease,...     

EEG–mapping differences between narcolepsy patients and controls and subsequent double–blind,placebo–controlled studies with modafinil

The aim of the present study was to investigate the role of EEG mapping as an objective and quantitative measure of vigilance in untreated and modafinil–treated narcoleptics, and compare it with the conventional neurophysiological method of the Multiple Sleep Latency Test (MSLT) and the subjective Epworth Sleepiness Scale (ESS). In 16 drug–free narcoleptics and 16 normal controls a baseline 3–min vigilance–controlled EEG (V–EEG) and a 4–min resting EEG (R–EEG) were recorded during midmorning hours. Thereafter, in a double–blind, placebo–controlled crossover design, patients were treated with a 3–week fixed titration of modafinil (200, 300, 400 mg) and placebo. EEG–mapping, MSLT and ESS measures were obtained before and at the end of the third week of therapy. Statistical overall analysis by means of the omnibus significance test demonstrated significant EEG differences between untreated patients and controls in the resting condition only (R–EEG). Subsequent univariate analysis revealed an increase in absolute and relative theta power, a decrease in alpha–2 and beta power as well as a slowing of the dominant frequency and the centroids of the alpha, beta and total power spectrum and thus objectified a vigilance decrement in narcolepsy. Modafinil 400 mg/d significantly improved vigilance as compared with placebo (p 0.01), inducing changes opposite to the aforementioned baseline differences (key–lock principle). The MSLT and the ESS also improved under modafinil as compared with placebo, but changes were less consistent. Spearman rank correlations revealed the highest correlations between EEG mapping and the ESS, followed by those between EEG mapping and the MSLT, while the lowest correlation was found between the MSLT and the ESS. In conclusion, EEG mapping is a valuable instrument for measuring vigilance decrements in narcolepsy and their improvement under psychostimulant treatment.     

Mrp1 is essential for sphingolipid signaling to p-glycoprotein in mouse blood–brain and blood–spinal cord barriers

At the blood–brain and blood–spinal cord barriers, P-glycoprotein, an ATP-driven drug efflux pump, is a major obstacle to central nervous system (CNS) pharmacotherapy. Recently, we showed that signaling through tumor necrosis factor-α (TNF-α), sphingolipids, and sphingosine-1-phosphate receptor 1 (S1PR1) rapidly and reversibly reduced basal P-glycoprotein transport activity in the rat blood–brain barrier. The present study extends those findings to the mouse blood–brain and blood–spinal cord barriers and, importantly, identifies multidrug resistance-associated protein 1 (Mrp1, Abcc1) as the transporter that mediates S1P efflux from brain and spinal cord endothelial cells. In brain and spinal cord capillaries isolated from wild-type mice, TNF-α, sphingosine, S1P, the S1PR agonist fingolimod (FTY720), and its active, phosphorylated metabolite, FTY720P, reduced P-glycoprotein transport activity; these effects were abolished by a specific S1PR1 antagonist. In brain and spinal cord capillaries isolated from Mrp1-null mice, neither TNF-α nor sphingosine nor FTY720 reduced P-glycoprotein transport activity. However, S1P and FTY720P had the same S1PR1-dependent effects on transport activity as in capillaries from wild-type mice. Thus, deletion of Mrp1 alone terminated endogenous signaling to S1PR1. These results identify Mrp1 as the transporter essential for S1P efflux from the endothelial cells and thus for inside-out S1P signaling to P-glycoprotein at the blood–brain and blood–spinal cord barriers.     

Narcolepsy–cataplexy and schizophrenia in adolescents

BackgroundDespite advances in the understanding of narcolepsy, little information the on association between narcolepsy and psychosis is available, except for amphetamine-related psychotic reactions. Our case-control study aimed to compare clinical differences and analyze risk factors in children who developed narcolepsy with cataplexy (N–C), schizophrenia, and N–C followed by schizophrenia.MethodsThree age- and gender-matched groups of children with N–C schizophrenia (study group), N–C (control group 1), and schizophrenia only (control group 2) were investigated. Subjects filled out sleep questionnaires, sleep diaries, and quality of life scales, followed by polysomnography (PSG), multiple sleep latency tests (MSLT), routine blood tests, HLA typing, genetic analysis of genes of interest, and psychiatric evaluation. The risk factors for schizophrenia also were analyzed.ResultsThe study group was significantly overweight when measuring body mass index (BMI) (P = .016), at narcolepsy onset compared to control group 1, and the study group developed schizophrenia after a mean of 2.55 ± 1.8 years. Compared to control group 2, psychotic symptoms were significantly more severe in the study group, with a higher frequency of depressive symptoms and acute ward hospitalization in 8 out of 10 of the subjects. They also had poorer long-term response to treatment, despite multiple treatment trials targeting their florid psychotic symptoms. All subjects with narcolepsy were HLA DQ B1¹0602 positive. The study group had a significantly higher frequency of DQ B1¹-03:01/06:02 (70%) than the two other groups, without any significant difference in HLA-DR typing, tumor necrosis factor α (TNF-α) levels, hypocretin (orexin) receptor 1 gene, HCRTR1, and the hypocretin (orexin) receptor 2 gene, HCRTR2, or blood infectious titers.ConclusionBMI and weight at onset of narcolepsy as well as a higher frequency of DQ B1¹-03:01/06:02 antigens were the only significant differences in the N–C children with secondary schizophrenia; such an association is a therapeutic challenge with long-term persistence of severe psychotic symptoms.     

Obstructive sleep apnoea syndrome is associated with relative hypocortisolemia and decreased hypothalamo–pituitary–adrenal axis response to 1 and 250 μg ACTH and glucagon stimulation tests

ObjectiveThe investigations regarding the effect of obstructive sleep apnoea syndrome (OSAS) on hypothalamo–pituitary–adrenal (HPA) axis revealed conflicting results. We aimed to evaluate the effects of OSAS on HPA-axis with dynamic tests.MethodsThis study was carried out on 26 patients with OSAS and 15 subjects without OSAS which, were defined according to the International Classification of Sleep Disorders. Patients were enrolled from either Endocrinology outpatient clinic or Neurology Sleep Center. Participants for the control group were included from the patients admitting to Endocrinology Department with the complaint of obesity or volunteers from hospital staff. All the participants were evaluated by polysomnography (PSG) and dynamic tests of HPA axis (dexamethasone suppression test, 1 and 250 μg ACTH and glucagon stimulation tests).ResultsSerum basal and peak cortisol levels were found to be lower in OSAS patients when compared to the control group during 1 μg ACTH and glucagon stimulation tests. When the area under curve (AUC) of cortisol responses to dynamic stimulation tests were calculated according to trapezoid formula, patients with OSAS were found to have lower values compared to control group. AUC responses of all three dynamic stimulation tests were found to be negatively correlated with AHI.ConclusionOSAS is associated with relative hypocortisolemia in the morning with reduced responses to 1 and 250 μg ACTH and glucagon stimulation tests.     

Obsessive–compulsive disorder and personality disorder

BACKGROUND: Previous studies indicate that most individuals with obsessive-compulsive disorder (OCD) have comorbid personality disorders (PDs), particularly from the anxious cluster. However, the nature and strength of this association remains unclear, as the majority of previous studies have relied heavily on clinical populations. We analysed the prevalence of screen positive personality disorder in a representative sample of adults with OCD living in private households in the UK. METHODS: A secondary analysis of data from the 2000 British National Survey of Psychiatric Morbidity. The prevalence of PD, as determined by the SCID-II questionnaire, was compared in participants with OCD, with other neuroses and non-neurotic controls. Within the OCD group we also analysed possible differences relating to sex and subtypes of the disorder. RESULTS: The prevalence of any screen positive PD in the OCD group (N=108) was 74%, significantly greater than in both control groups. The most common screen positive categories were paranoid, obsessive-compulsive, avoidant, schizoid and schizotypal. Compared to participants with other neuroses, OCD cases were more likely to screen positively for paranoid, avoidant, schizotypal, dependent and narcissistic PDs. Men with OCD were more likely to screen positively for PDs in general, cluster A PDs, antisocial, obsessive-compulsive and narcissistic categories. The presence of comorbid neuroses in people with OCD had no significant effect on the prevalence of PD. CONCLUSIONS: Personality pathology is highly prevalent among people with OCD who are living in the community and should be routinely assessed, as it may affect help-seeking behaviour and response to treatment.     

Blood–brain barrier dysfunction and recovery

Summary. In this paper we discuss the importance of the blood–brain barrier (BBB) as an interface between blood and brain. Many (brain) diseases change the functionality and integrity of the BBB. Mostly this results in increased BBB permeability. Therefore we have studied de various signal transduction routes that are influenced by inflammatory stimuli. The radical scavenger N-acetylcysteine was able to protect the BBB against inflammatory stimuli. Similar results were found following application of glucocorticoids. In addition, it was observed that glucocorticoids and interferon-α,β increased the tightness of the in vitro BBB and when given together a potentiating effect was seen.