Progressive central cardiorespiratory rate downregulation and intensifying epilepsy lead to sudden unexpected death in epilepsy in mouse model of the most common human ATP1A3 mutation.

Objective: This study was undertaken to test the following hypotheses in the Atp1a3 mouse (which carries the most common human ATP1A3 (the major subunit of the neuronal Na/K-adenosine triphosphatase [ATPase]) mutation, D801N): sudden unexpected death in epilepsy (SUDEP) occurs during seizures and is due to terminal apneas in some and due to lethal cardiac arrhythmias in others; and Atp1a3 mice have central cardiorespiratory dysregulation and abnormal respiratory drive.

Methods: Comparison was made of littermate wild-type and Atp1a3 groups using (1) simultaneous in vivo video-telemetry recordings of electroencephalogram, electrocardiogram, and breathing; (2) whole-body plethysmography; and (3) hypoglossal nerve recordings.

Results: In Atp1a3 mice, (1) SUDEP consistently occurred during seizures that were more severe than preterminal seizures; (2) seizure clustering occurred in periods preceding SUDEP; (3) slowing of breathing rate (BR) and heart rate was observed preictally before preterminal and terminal seizures; and (4) the sequence during terminal seizures was as follows: bradypnea with bradycardia/cardiac arrhythmias, then terminal apnea, followed by terminal cardiac arrhythmias.

Real life retrospective study of cannabidiol therapy in alternating hemiplegia of childhood.

Background: Many alternating hemiplegia of childhood (AHC) patients have received Cannabidiol (CBD) but, to our knowledge, there are no published data available.

Goals: Test the hypothesis that CBD has favorable effects on AHC spells.

Methods: Retrospective review of available data of AHC patients who received CBD.

Neuronal mechanism of a BK channelopathy in absence epilepsy and dyskinesia.

A growing number of gain-of-function (GOF) BK channelopathies have been identified in patients with epilepsy and movement disorders. Nevertheless, the underlying pathophysiology and corresponding therapeutics remain obscure. Here, we utilized a knock-in mouse model carrying human BK-D434G channelopathy to investigate the neuronal mechanism of BK GOF in the pathogenesis of epilepsy and dyskinesia.

Adeno-Associated Virus-Mediated Gene Therapy in the Mashlool, , Mouse Model of Alternating Hemiplegia of Childhood.

Alternating Hemiplegia of Childhood (AHC) is a devastating autosomal dominant disorder caused by mutations, resulting in severe hemiplegia and dystonia spells, ataxia, debilitating disabilities, and premature death. Here, we determine the effects of delivering an extra copy of the normal gene in a mouse model carrying the most common mutation causing AHC in humans, the D801N mutation. We used an adeno-associated virus serotype 9 (AAV9) vector expressing the human gene under the control of a human Synapsin promoter.

Early onset severe ATP1A2 epileptic encephalopathy: Clinical characteristics and underlying mutations.

Background: ATP1A2 mutations cause hemiplegic migraine with or without epilepsy or acute reversible encephalopathy. Typical onset is in adulthood or older childhood without subsequent severe long-term developmental impairments.

Aim: We aimed to describe the manifestations of early onset severe ATP1A2-related epileptic encephalopathy and its underlying mutations in a cohort of seven patients.

Cardiac phenotype in -related syndromes: A multicenter cohort study.

Objective: To define the risks and consequences of cardiac abnormalities in -related syndromes.

Methods: Patients meeting clinical diagnostic criteria for rapid-onset dystonia-parkinsonism (RDP), alternating hemiplegia of childhood (AHC), and cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss (CAPOS) with genetic analysis and at least 1 cardiac assessment were included. We evaluated the cardiac phenotype in an knock-in mouse (Mashl) to determine the sequence of events in seizure-related cardiac death.

D-DEMØ, a distinct phenotype caused by mutations.

Objective: To describe a phenotype caused by mutations, which manifests as dystonia, dysmorphism of the face, encephalopathy with developmental delay, brain MRI abnormalities always including cerebellar hypoplasia, no hemiplegia (Ø) (D-DEMØ), and neonatal onset.

Methods: Review and analysis of clinical and genetic data.

Results: Patients shared the above traits and had whole-exome sequencing that showed de novo variants of the gene, predicted to be disease causing and occurring in regions of the protein critical for pump function.

The epileptology of alternating hemiplegia of childhood.

Objective: To report our experience and investigate 5 original hypotheses: (1) multiple types of epileptic seizures occur in alternating hemiplegia of childhood (AHC), and these can be the initial presentation; (2) epileptiform abnormalities often appear well after clinical seizures; (3) nonepileptic reduced awareness spells (RAS) occur frequently; (4) epilepsy is commonly drug resistant but may respond to vagal nerve stimulation (VNS); and (5) status epilepticus (SE) is common and is usually refractory and recurrent.

Methods: We analyzed a cohort of 51 consecutive patients with AHC.

Results: Thirty-two of 51 patients had epilepsy: 18 focal seizures, frontal more frequently than temporal, and then posterior.

Novel E815K knock-in mouse model of alternating hemiplegia of childhood.

De novo mutations causing dysfunction of the ATP1A3 gene, which encodes the α3 subunit of Na/K-ATPase pump expressed in neurons, result in alternating hemiplegia of childhood (AHC). AHC manifests as paroxysmal episodes of hemiplegia, dystonia, behavioral abnormalities, and seizures. The first aim of this study was to characterize a novel knock-in mouse model (Atp1a3, Matoub, Matb) containing the E815K mutation of the Atp1a3 gene recognized as causing the most severe and second most common phenotype of AHC with increased morbidity and mortality as compared to other mutations.

Mechanisms of increased hippocampal excitability in the Mashl mouse model of Na /K -ATPase dysfunction.

Objective: Na /K -ATPase dysfunction, primary (mutation) or secondary (energy crisis, neurodegenerative disease) increases neuronal excitability in the brain. To evaluate the mechanisms underlying such increased excitability we studied mice carrying the D801N mutation, the most common mutation causing human disease, specifically alternating hemiplegia of childhood (AHC) including epilepsy. Because the gene is expressed in all neurons, particularly γ-aminobutyric acid (GABA)ergic interneurons, we hypothesized that the pathophysiology would involve both pyramidal cells and interneurons and that fast-spiking interneurons, which have increased firing rates, would be most vulnerable.

Diagnosis and Treatment of Alternating Hemiplegia of Childhood.

The diagnosis and treatment of patients with Alternating Hemiplegia of Childhood (AHC) and related disorders should be provided by a multidisciplinary team experienced with the spectrum of presentations of this disease, with its related disorders, with its complex and fluctuating manifestations, and with cutting edge advances occurring in the field. Involvement in research to advance the understanding of this disease and partnership with international collaborators and family organizations are also important. An example of such an approach is that of The Duke AHC and Related Disorders Multi-Disciplinary Clinic and Program, which, in partnership with the Cure AHC Foundation, has developed and applied this approach to patients seen since early 2013.

Pediatric Sudden Unexpected Death in Epilepsy: What Have we Learned from Animal and Human Studies, and Can we Prevent it?

Several factors, such as epilepsy syndrome, poor compliance, and increased seizure frequency increase the risks of sudden unexpected death in epilepsy (SUDEP). Animal models have revealed that the mechanisms of SUDEP involve initially a primary event, often a seizure of sufficient type and severity, that occurs in a brain, which is vulnerable to SUDEP due to either genetic or antecedent factors. This primary event initiates a cascade of secondary events starting, as some models indicate, with cortical spreading depolarization that propagates to the brainstem where it results in autonomic dysfunction.

Spinal electro-magnetic stimulation combined with transgene delivery of neurotrophin NT-3 and exercise: novel combination therapy for spinal contusion injury.

Our recent terminal experiments revealed that administration of a single train of repetitive spinal electromagnetic stimulation (sEMS; 35 min) enhanced synaptic plasticity in spinal circuitry following lateral hemisection spinal cord injury. In the current study, we have examined effects of repetitive sEMS applied as a single train and chronically (5 wk, every other day) following thoracic T10 contusion. Chronic studies involved examination of systematic sEMS administration alone and combined with exercise training and transgene delivery of neurotrophin [adeno-associated virus 10-neurotrophin 3 (AAV10-NT3)].

Knock-in mouse model of alternating hemiplegia of childhood: behavioral and electrophysiologic characterization.

Objectives: Mutations in the ATP1α3 subunit of the neuronal Na+/K+-ATPase are thought to be responsible for seizures, hemiplegias, and other symptoms of alternating hemiplegia of childhood (AHC). However, the mechanisms through which ATP1A3 mutations mediate their pathophysiologic consequences are not yet understood. The following hypotheses were investigated: (1) Our novel knock-in mouse carrying the most common heterozygous mutation causing AHC (D801N) will exhibit the manifestations of the human condition and display predisposition to seizures; and (2) the underlying pathophysiology in this mouse model involves increased excitability in response to electrical stimulation of Schaffer collaterals and abnormal predisposition to spreading depression (SD).

Combination of chondroitinase ABC and AAV-NT3 promotes neural plasticity at descending spinal pathways after thoracic contusion in rats.

Transmission through descending pathways to lumbar motoneurons, although important for voluntary walking in humans and rats, has not been fully understood at the cellular level in contusion models. Major descending pathways innervating lumbar motoneurons include those at corticospinal tract (CST) and ventrolateral funiculus (VLF). We examined transmission and plasticity at synaptic pathways from dorsal (d)CST and VLF to individual motoneurons located in ventral horn and interneurons located in dorsomedial gray matter at lumbar segments after thoracic chronic contusion in adult anesthetized rats.

Neutralization of inhibitory molecule NG2 improves synaptic transmission, retrograde transport, and locomotor function after spinal cord injury in adult rats.

NG2 belongs to the family of chondroitin sulfate proteoglycans that are upregulated after spinal cord injury (SCI) and are major inhibitory factors restricting the growth of fibers after SCI. Neutralization of NG2's inhibitory effect on axon growth by anti-NG2 monoclonal antibodies (NG2-Ab) has been reported. In addition, recent studies show that exogenous NG2 induces a block of axonal conduction.

Repetitive spinal electromagnetic stimulation opens a window of synaptic plasticity in damaged spinal cord: role of NMDA receptors.

As we reported previously, propagation of action potentials through surviving axons is impaired dramatically, resulting in reduced transmission to lumbar motoneurons after midthoracic lateral hemisection (HX) in rats. The aim of the present study was to evoke action potentials through the spared fibers using noninvasive electromagnetic stimulation (EMS) over intact T2 vertebrae in an attempt to activate synaptic inputs to lumbar motoneurons and thus to enhance plasticity of spinal neural circuits after HX. We found that EMS was able to activate synaptic inputs to lumbar motoneurons and motor-evoked potentials (MEP) in hindlimb muscles in adult anesthetized rats.

Combined delivery of Nogo-A antibody, neurotrophin-3 and the NMDA-NR2d subunit establishes a functional 'detour' in the hemisected spinal cord.

To encourage re-establishment of functional innervation of ipsilateral lumbar motoneurons by descending fibers after an intervening lateral thoracic (T10) hemisection (Hx), we treated adult rats with the following agents: (i) anti-Nogo-A antibodies to neutralize the growth-inhibitor Nogo-A; (ii) neurotrophin-3 (NT-3) via engineered fibroblasts to promote neuron survival and plasticity; and (iii) the NMDA-receptor 2d (NR2d) subunit via an HSV-1 amplicon vector to elevate NMDA receptor function by reversing the Mg(2+) block, thereby enhancing synaptic plasticity and promoting the effects of NT-3. Synaptic responses evoked by stimulation of the ventrolateral funiculus ipsilateral and rostral to the Hx were recorded intracellularly from ipsilateral lumbar motoneurons. In uninjured adult rats short-latency (1.

Alterations of action potentials and the localization of Nav1.6 sodium channels in spared axons after hemisection injury of the spinal cord in adult rats.

Previously, we reported a pronounced reduction in transmission through surviving axons contralateral to chronic hemisection (HX) of adult rat spinal cord. To examine the cellular and molecular mechanisms responsible for this diminished transmission, we recorded intracellularly from lumbar lateral white matter axons in deeply anesthetized adult rats in vivo and measured the propagation of action potentials (APs) through rubrospinal/reticulospinal tract (RST/RtST) axons contralateral to chronic HX at T10. We found decreased excitability in these axons, manifested by an increased rheobase to trigger APs and longer latency for AP propagation passing the injury level, without significant differences in axonal resting membrane potential and input resistance.

Role of chondroitin sulfate proteoglycans in axonal conduction in Mammalian spinal cord.

Chronic unilateral hemisection (HX) of the adult rat spinal cord diminishes conduction through intact fibers in the ventrolateral funiculus (VLF) contralateral to HX. This is associated with a partial loss of myelination from fibers in the VLF (Arvanian et al., 2009).

Chronic spinal hemisection in rats induces a progressive decline in transmission in uninjured fibers to motoneurons.

Although most spinal cord injuries are anatomically incomplete, only limited functional recovery has been observed in people and rats with partial lesions. To address why surviving fibers cannot mediate more complete recovery, we evaluated the physiological and anatomical status of spared fibers after unilateral hemisection (HX) of thoracic spinal cord in adult rats. We made intracellular and extracellular recordings at L5 (below HX) in response to electrical stimulation of contralateral white matter above (T6) and below (L1) HX.

Effect of hydrogen peroxide on neuron sensitivity to acetylcholine.

The dose-dependent effect of hydrogen peroxide on snail neuromembrane chemosensitivity was studied by means of standard voltage-clamp method. Short-term exposure (7 min) of neurons to H(2)O(2) (10(-11)-10(-4) M) caused dose-dependent depression of Acetylcholine (Ach)-induced ionic currents in the membrane. The H(2)O(2)-induced depression of Ach-sensitivity of membrane was more pronounced in K(+)-free solution than in normal physiological solution and it disappeared in cold medium (5 degrees C).