This study was conducted to characterize cellular changes occurring during the progression of status epilepticus (SE) that could lead to the maintenance of increased membrane excitability. SE was induced by injection of pilocarpine after which rats were monitored both electrographically and behaviorally. After various lengths of time in SE, specific brain regions were isolated for biochemical study. SE resulted in an early maintenance of PKA activity in both cortical homogenate and crude synaptoplasmic membrane (crude SPM) fractions. At subsequent stages of SE there was a significant increase in PKA activity in both homogenate and crude SPM fractions. Wester blot analysis showed that alteration of PKA protein expression was not responsible for the increase in PKA activity. These results show that SE has a significant duration-dependent effect on PKA activity. Combined with other cellular changes these findings, could represent a mechanism for the formation for potentiated seizure states like epilepsy.

Fast postsynaptic inhibition in the brain is mediated by ionotropic GABA_A receptors (GABA_ARs), which are activated by the release of the neurotransmitter GABA from presynaptic interneurons. The GABA_AR is primarily permeable to chloride ions (Cl-) and therefore the transmembrane gradient for Cl- sets the reversal potential of the receptor (E_GABA-A). When intracellular Cl^- concentrations are relatively low, E_GABA-A is more negative than the membrane potential and GABA_AR responses will have a hyperpolarising and inhibitory effect upon the postsynaptic cell. In contrast, when intracellular Cl^- concentrations are relatively high, E_GABA-A will be more positive and GABA_AR activation will have a depolarising effect. How a neuron controls its intracellular Cl^- concentrations is a fundamental question that has direct relevance to hyperexcitability conditions such as epilepsy. Recently, it has become clear that Cl^- homeostasis is altered in epileptic tissue such that postsynaptic inhibition via the GABA_AR is reduced and, under some conditions, GABA_AR signalling may even be excitatory. In my thesis I explore some of the mechanisms and factors that are responsible for regulating postsynaptic GABA_AR signalling in the context of epileptic seizure activity in the rat hippocampus. In the first series of experiments I combined pharmacological approaches with electrophysiological recordings from pyramidal neurons in the CA3 region of the hippocampus to trigger seizure activity. My results show that intense neuronal activity during a seizure leads to a transient accumulation of intracellular Cl^-, which generates a pronounced depolarising shift in E_GABA-A. Under these conditions, GABAergic synapses become excitatory and contribute to ongoing neuronal activity rather than exerting their normal inhibitory role. I found that the same seizure activity also induces the release of a neuromodulator called adenosine, which serves to limit the deleterious effects of excitatory GABA_AR responses. Adenosine exerts these effects by activating downstream potassium channels, which increase the postsynaptic cell’s membrane conductance and, in doing so, ‘shunt’ incoming GABA_AR responses. In the second series of experiments I examined Cl^- homeostasis and E_GABA-A in the context of neonatal seizures. One of the main mechanisms by which neurons maintain their intracellular Cl^- levels is through the activity of ion transporter proteins that reside in the membrane and move Cl^- either into, or out of, the cell. I discovered that the intracellular trafficking of an important Cl^- transporter protein, NKCC1, correlates with changes in Cl^- homeostasis. Using a combination of biochemical and molecular techniques, I then identified a novel molecular association between NKCC1 and a motor protein, Myosin Va, which has been implicated in the intracellular trafficking of membrane proteins. Using electrophysiological recordings I found that Myosin Va is required for NKCC1’s contribution to Cl^- homeostasis, which may be important for E_GABA-A changes in epilepsy. In the final series of experiments I developed methods to study the temporal dynamics in E_GABA-A during a single seizure. These revealed a Cl^- unloading mechanism that emerges at the end of a seizure and which depends upon hyperpolarisation of the postsynaptic membrane potential. This mechanism aids E_GABA-A recovery after the seizure and moves E_GABA-A to more hyperpolarised values. This mechanism could boost postsynaptic inhibition after a seizure and thereby help to protect against further seizure episodes. In conclusion, this work extends our understanding of postsynaptic GABAergic transmission in the context of epileptic seizure activity and suggests new mechanisms that could be relevant for the development of rational anti-epileptic treatments.

Charles University in Prague Faculty of Pharmacy in Hradec Králové Department of Pharmacology & Toxicology Student: Lucie Chaloupková Supervisor: Prof. MUDr. Radomír Hrdina, CSc. Title of diploma thesis: Treatment of epilepsy Epilepsy is a serious chronic disease affecting all ages which can be characterized by recurrent epileptic attacks. It affects about 1,3-4 % of the population and endangers the patient's life at every incoming attack. Long-term treatment must be preceded by thorough diagnosis and classification of the disease, which can be very difficult. The aim of the treatment is to prevent recurrent epileptic attacks, or at least mitigate them while minimizing the side effects of the treatment and reducing the negative impact on the quality of life. When choosing a suitable drug for an adult, the doctor usually decides individually depending on the type of epileptic attack. In children, the choice of the treatment often depends on the diagnosed type of syndrome, which appears more in the lower age category than in adult patients. The doctor should follow expert standards of the treatment of epilepsy, and also their own most recent experience and knowledge gained during the course of lifelong learning. The therapy begins with monotherapy, and only when not successful, it is necessary to...

The prevalence of autism spectrum disorders [ASD] in epilepsy is approximately 20%-32%, with previous research reporting high rates of under-diagnosis of ASD in epilepsy. Current psychological assessments were adapted to provide epilepsy-specific measures of behaviour, which increased validity by addressing specific methodological problems highlighted by several researchers. The initial experiments provided a comprehensive investigation of autistic traits and characteristics in a heterogeneous group of adults with epilepsy without any ASD diagnosis to quantify the extent to which autistic characteristics are related to seizure activity. Adults with epilepsy showed higher autistic traits and impaired social responsiveness while systemizing and empathising abilities remained intact. Further, autistic traits and impaired social responsiveness increased again during seizure activity. Social responsiveness positively correlated with anti-epileptic drug [AED] control. Adults with epilepsy and seizure remission demonstrated significant improvements in restricted, repetitive behaviours compared to adults with current epileptic seizures. Together, these results demonstrate a relationship between seizure activity and autistic characteristics, and are consistent with previous suggestions that AEDs may mask autistic characteristics. The impaired social skills and communication are consistent with research suggesting that the pathogenesis of epilepsy may disrupt social functioning. However, whether this can be directly attributed to social cognitive deficits remains uncertain. The main research addresses this uncertainty by conducting three experiments to assess the Somatic Marker Hypothesis and the mechanisms which underpin it. The rationale is to establish whether this is a valid explanatory model for disrupted neurobiological factors implicated in social cognitive processing. This hypothesis is appropriate for investigating adults with epilepsy, some who may have developed typical social abilities in early life before epilepsy onset. Results from the IOWA Gambling Task demonstrated that adults with epilepsy had impaired decision making abilities compromising somatic marker formation, crucial for social cognition. However, this deficit occurred in the absence of other socio-emotional and memory impairments. In conclusion, adults with epilepsy have a higher rate of autistic characteristics, and their social difficulties may be associated with compromised somatic marker formation. Future research needs to determine the heritability of these autistic traits and characteristics.

La saisie-appréhension, en dépit de sa nouveauté, reste de nos jours largement ignorée par la doctrine. Pourtant, en venant assurer l’exécution forcée en nature de certaines obligations de faire (celles de livraison/délivrance et restitution de biens meubles corporels), cette mesure offre de nouvelles perspectives et ce, tant dans les procédures civiles d’exécution que dans le droit des obligations. En effet, son objectif repose sur une logique différente de celle qui gouverne traditionnellement les saisies et cette nouvelle logique qu’elle incarne conduit à une résolution des problèmes touchant la classification des obligations selon leur objet.Cette étude se propose ainsi de cerner cette mesure et de montrer les intérêts qu’elle présente, ce qui amènera à des analyses à la fois dans les voies d’exécution et dans le droit substantiel. Au terme de celle-ci, la saisie-appréhension se révèlera comme l’autre figure de l’exécution forcée en nature. / The saisie-appréhension, in spite of its newness, stays nowadays widely unknown by the doctrine. However, in so far as it stands ensure for specific performance of some obligations to do like delivery or restitution of tangible movables, this measure offers new prospects concerning the civil proceedings of execution as well as Law of obligations. Its aim is based indeed on a logical different from the one which controls traditionally the other executions all, this new logical allows to resolve problems about the classification of obligation in accordance with their object.This study has so in view to determine this measure and to show its interests, what induces to analysis in Law of seizures and in substantial law. At the end of this one, the saisie-appréhension will come to light as the other face of specific performance.

Diseases such as epilepsy, pain, and neurodegenerative disorders are associated with changes in neuronal dysfunction due to an imbalance of excitation and inhibition. This work details a novel electroconvulsive seizure assay for C. elegans using the well characterized cholinergic and GABAergic excitation and inhibition of the body wall muscles and the resulting locomotion patterns to better understand neuronal excitability. The time to recover normal locomotion from an electroconvulsive seizure could be modulated by increasing and decreasing inhibition. GABAergic deficits and a chemical proconvulsant resulted in an increased recovery time while anti-epileptic drugs decreased seizure duration. Successful modulation of excitation and inhibition in the new assay led to the investigation of a cGMP-dependent protein kinase (PKG) which modulates potassium (K+) channels, affecting neuronal excitability, and determined that increasing PKG activity decreases the time to recovery from an electroconvulsive seizure. The new assay was used as a forward genetic screening tool using C. elegans and several potential genes that affect seizure susceptibility were found to take longer to recover from a seizure. A naturally occurring polymorphism for PKG in D. melanogaster confirmed that both genetic and pharmacological manipulation of PKG influences seizure duration. PKG has been implicated in stress tolerance, which can be affected by changes in neuronal excitability associated with aging, so stress tolerance and locomotor behavior in senescent flies was investigated. For the first time, PKG has been implicated in aging phenotypes with high levels of PKG resulting in reduced locomotion and lifespan in senescent flies. The results suggest a potential new role for PKG in seizure susceptibility and aging. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection

Degree awarded (2004): PhDBmS, Neuroscience Program, George Washington University / Glutamate is critically important as an excitatory neurotransmitter in the central nervous system. Increasing evidence suggests additional signaling roles for glutamate in cell proliferation and migration in normal and oncogenic states. Recently, glutamate release from glioma cells has been shown to increase tumor growth in vivo. To investigate the mechanism of glutamate enhancement of tumor growth, we investigated the effect of glutamate on tumor cell proliferation, invasion, and glioma-induced cell death. Here we demonstrate that glutamate enhances tumor growth via increasing tumor cell proliferation and inducing excitotoxic death of cells surrounding the solid tumor mass, thereby facilitating tumor expansion. The evidence that glutamate enhances tumor growth suggests that regulating extracellular levels of glutamate may restrict tumor growth. In the normal brain, extracellular glutamate levels are maintained by a family of glutamate transporters. To investigate the therapeutic potential of regulating extracellular glutamate concentrations on tumor growth, we utilized a transgenic mouse model of EAAT2 glutamate transporter overexpression. In this report, we demonstrate that increased glutamate transport limits tumor growth in vivo and provides protection against glioma-associated neuronal cell death. In addition, seizure activity, often associated with the presence of a CNS tumor, is attenuated in transgenic mice overexpressing the glutamate transporter, EAAT2. These findings suggest that glutamate transporters may provide a new therapeutic target for limiting tumor expansion and secondary epileptogenesis. / Advisory Committee: Dr. Margaret Sutherland (Chair), Dr. Steven Patierno (Chair), Dr. Tim Hales, Dr. Vincent Chiappinelli, Dr. Linda Werling, Dr. Frances Noonan

Thesis (Ph. D.)--University of Virginia, 2006. / Includes bibliographical references. Also available online through Digital Dissertations.

Fever in infants younger than 2 months of age causes a significant number of emergency department visits and is particularly worrisome because of the potential for serious infection. Management of febrile infants is problematic because clinical observation is not a reliable indicator of serious bacterial illness (SBI), such as bacteremia, meningitis, and urinary tract infection (UTI). Numerous investigators have proposed methods of screening laboratory tests to ascertain the risk of SBI in febrile infants. These screening tests could potentially avoid the invasive and costly sepsis work-up, which usually includes complete blood count (CBC), blood culture, urinalysis, urine culture, and lumbar puncture. We conducted a prospective, cross-sectional study that examined the prevalence of rhinovirus (RV) and coronavirus (CoV), which are two of the most common causes of upper respiratory infections in the first year of life, and human metapneumovirus (hMPV), which is a common cause of bronchiolitis, in infants younger than 2 months of age. This study also examined whether febrile infants with RV were more or less likely to also have a SBI than infants without a viral respiratory infection. Methodology: Fever was defined as rectal temperatures greater than 37.9C or a historical fever greater than 100.3F. Nasal swabs were tested with reverse transcriptase polymerase chain reaction (rt-PCR) techniques for rhinoviruses (RV), human metapneumovirus (hMPV) and coronaviruses (CoV). Nasal samples were also tested for RSV, influenza A and B, parainfluenza types 1, 2 and 3, and adenovirus via direct fluorescent antibody (DFA). Conclusion: Rhinovirus (RV) was the most commonly detected respiratory viral pathogen in our cohort (14% out of 98 total enrolled patients). Coronovirus (CoV) and human metapneumovirus (hMPV) were both detected but in only one patient (1%) each. RV occurred predominantly in the summer (79%). This cohort of patients showed no difference between the incidence of serious bacterial illness (SBI) with and without RV infection (p=0.84).

Absence seizures in Childhood Absence Epilepsy (CAE) are 5 10 second episodes of impaired consciousness that are characterized on electroencephalography (EEG) by frontally-predominant, 3 4 Hz spike and wave discharges (SWD). The aims of this study were to use simultaneous EEG, functional magnetic resonance imaging (fMRI), and behavioral testing to identify the neural networks involved in absence seizures as well as to examine the timecourse of those ictal fMRI changes. It was hypothesized that absence seizures involve wide-reaching neural networks including the areas traditionally associated with normal attention processing and that absence seizures produce fMRI signal changes not only during the seizure, but before and after it as well. In this study, we recorded 88 absence seizures from a cohort of 42 children with pure CAE. These seizures were recorded as subjects participated in simultaneous EEG-fMRI scanning while engaged in a continuous performance task (CPT) of attentional vigilance or a repetitive tapping task (RTT) requiring repetitive motor activity. Using a novel, voxel-based percent fMRI change analysis combined with a volume of interest analysis, the second-by-second fMRI signal timecourse of the absence seizures were examined across numerous brain regions of interest, from 20 seconds before seizure onset through 40 seconds after seizure onset. EEG frequency analysis revealed seizures with a mean duration of 6.6 seconds and an abrupt onset and ending that were comprised of frontally-predominant, 3 4 Hz SWD. Ictal behavioral testing demonstrated abrupt onset of impairments during periods of SWD. These behavioral impairments were typical of CAE absence seizures in that impairments were greater in the CPT of attentional vigilance (omission error rate, OER = 81%) than in RTT testing (OER = 39 %) (p < 0.003). The ictal fMRI changes we observed varied depending upon the method of fMRI signal analysis used. Using the traditional general liner model, and assuming the standard hemodynamic response (HRF) function, this study replicated results consistent with previous ictal absence fMRI studies showing ictal activations primarily in the thalamus and ictal deactivations in traditional default mode areas. Using a more data-driven, novel voxel-based fMRI percentage change analysis to examine the ictal fMRI timecourse on a second-by-second basis, both ictally as well as pre- and post- ictally, this study, however, demonstrated ictal involvement of diverse brain regions before, during, and after the seizure. Activation was demonstrated up to 16 seconds before seizure onset, starting first in the parietal and orbital-medial frontal cortices and progressing to lateral frontal and lateral temporal cortices followed by the occipital and Rolandic cortices and finally the thalamus. Deactivation followed a similar anatomic progression and lasted up to 17 seconds after the end of SWD. These findings reveal a complex and long-lasting sequence of fMRI changes in CAE absence seizures that are not detectable by conventional HRF modeling and are important in the understanding and eventual treatment of absence seizures associated with CAE.