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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
161

A Mathematical Model of CA1 Hippocampal Neurons with Astrocytic Input

Ferguson, Katie January 2009 (has links)
Over time astrocytes have been thought to function in an auxiliary manner, providing neurons with metabolic and structural support. However, recent research suggests they may play a fundamental role in the generation and propagation of focal epileptic seizures by causing synchronized electrical bursts in neurons. It would be helpful to have a simple mathematical model that represents this dynamic and incorporates these updated experimental results. We have created a two-compartment model of a typical neuron found in the hippocampal CA1 region, an area often thought to be the origin of these seizures. The focus is on properly modeling the astrocytic input to examine the pathological excitation of these neurons and subsequent transmission of the signals. In particular, we consider the intracellular astrocytic calcium fluctuations which are associated with slow inward currents in neighbouring neurons. Using our model, a variety of experimental results are reproduced, and comments are made about the potential differences between graded and “all-or-none” astrocytes.
162

Oscillatory Network Activity in Brain Functions and Dysfunctions

Adhikari, Bhim M 10 May 2014 (has links)
Recent experimental studies point to the notion that the brain is a complex dynamical system whose behaviors relating to brain functions and dysfunctions can be described by the physics of network phenomena. The brain consists of anatomical axonal connections among neurons and neuronal populations in various spatial scales. Neuronal interactions and synchrony of neuronal oscillations are central to normal brain functions. Breakdowns in interactions and modifications in synchronization behaviors are usual hallmarks of brain dysfunctions. Here, in this dissertation for PhD degree in physics, we report discoveries of brain oscillatory network activity from two separate studies. These studies investigated the large-scale brain activity during tactile perceptual decision-making and epileptic seizures. In the perceptual decision-making study, using scalp electroencephalography (EEG) recordings of brain potentials, we investigated how oscillatory activity functionally organizes different neocortical regions as a network during a tactile discrimination task. While undergoing EEG recordings, blindfolded healthy participants felt a linear three-dot array presented electromechanically, under computer control, and reported whether the central dot was offset to the left or right. Based on the current dipole modeling in the brain, we found that the source-level peak activity appeared in the left primary somatosensory cortex (SI), right lateral occipital complex (LOC), right posterior intraparietal sulcus (pIPS) and finally left dorsolateral prefrontal cortex (dlPFC) at 45, 130, 160 and 175 ms respectively. Spectral interdependency analysis showed that fine tactile discrimination is mediated by distinct but overlapping ~15 Hz beta and ~80 Hz gamma band large-scale oscillatory networks. The beta-network that included all four nodes was dominantly feedforward, similar to the propagation of peak cortical activity, implying its role in accumulating and maintaining relevant sensory information and mapping to action. The gamma-network activity, occurring in a recurrent loop linked SI, pIPS and dlPFC, likely carrying out attentional selection of task-relevant sensory signals. Behavioral measure of task performance was correlated with the network activity in both bands. In the study of epileptic seizures, we investigated high-frequency (> 50 Hz) oscillatory network activity from intracranial EEG (IEEG) recordings of patients who were the candidates for epilepsy surgery. The traditional approach of identifying brain regions for epilepsy surgery usually referred as seizure onset zones (SOZs) has not always produced clarity on SOZs. Here, we investigated directed network activity in the frequency domain and found that the high frequency (>80 Hz) network activities occur before the onset of any visible ictal activity, andcausal relationships involve the recording electrodes where clinically identifiable seizures later develop. These findings suggest that high-frequency network activities and their causal relationships can assist in precise delineation of SOZs for surgical resection.
163

Μελέτη ηλεκτροεγκεφαλογραφήματος με βάση μεγέθη από τη θεωρία πληροφορίας

Ξενικού, Μόνικα Φιλίτσα 20 October 2010 (has links)
Στην παρούσα μεταπτυχιακή διπλωματική εργασία, η κυματιδιακή ανάλυση (Wavelet Analysis) εφαρμόζεται σε ηλεκτροεγκεφαλικές καταγραφές ασθενών που πάσχουν από επιληψία και σε προκλητά δυναμικά ασθενών που πάσχουν από σχιζοφρένεια και αλκοολισμό, με σκοπό την ανάδειξη παθολογικών προτύπων. Συγκεκριμένα, χρησιμοποιείται ο Διακριτός Κυματιδιακός Μετασχηματισμός (Discrete Wavelet Transform) για την εκτίμηση της Εντροπίας (Entropy) τωνηλεκτροεγκεφαλικών σημάτων. Η Εντροπία είναι ένα μέγεθος το οποίο εκφράζει το βαθμό τάξης ενός σήματος. Βιοσήματα με μεγάλο βαθμό οργάνωσης και περιορισμένο συχνοτικό περιεχόμενο -που θεωρείται ότι εκφράζουν πιο συντονισμένη εγκεφαλική λειτουργία- έχουν χαμηλές τιμές Εντροπίας. Αντίθετα, όσο πιο στοχαστικό είναι ένα σήμα τόσο μεγαλύτερη η τιμή της Εντροπίας του. Για τη μελέτη μας υλοποιήσαμε δύο διαφορετικά μεγέθη Εντροπίας, την Κυματιδιακή Εντροπία (Wavelet Entropy) και την Εντροπία Renyi (Renyi Entropy), τα οποία έχουν διαφορετικές σχέσεις ορισμού αλλά εκφράζουν και τα δύο το βαθμό τάξης των αναλυόμενων σημάτων. Τα αποτελέσματα της ανάλυσης αποκαλύπτουν ότι και τα δύο αυτά μεγέθη Εντροπίας κατορθώνουν να εντοπίσουν την επιληπτική κρίση, καθώς η τιμή τους διαφοροποιείται κατά τη διάρκειά της σε σχέση με την τιμή τους πριν από αυτή. Ακόμα, στατιστική ανάλυση των αποτελεσμάτων για προκλητά δυναμικά αποκαλύπτει ότι είναι δυνατός ο διαχωρισμός των παθολογικών καταγραφών (σχιζοφρενών ή αλκοολικών) από αυτές υγιών μαρτύρων, σε συγκεκριμένες περιοχές ενδιαφέροντος των σημάτων. / Wavelet Analysis of EEG during epileptic seizures and evoked potentials of patients suffering from schizophrenia and alcoholism was carried out in the present project. Discrete Wavelet Transform was used to estimate the Entropy of patients’ biosignals. Entropy is a measure of the degree of order of a signal -and subsequently of the system it represents- also reflecting the complexity of its power spectrum. An ordered activity, like a sinusoidal signal, is manifested as a narrow peak in the frequency domain which corresponds to a low entropy value. On the other extreme, a disordered activity (e.g. the one generated by pure noise or by a deterministic chaotic system) will have a wide band response, thus being reflected in higher entropies. In our research we used two differently defined Entropies, Wavelet Entropy and Renyi Entropy, both revealing the degree of order of the signal. Results show that both Entropy measures accomplish the goal they were used for. They manage to detect the epileptic seizure as their value clearly decreased during seizure compared to the pre-ictal value. Also, statistically significant differences were observed between entropy values of ERPs of healthy subjects and patients suffering from schizophrenia and alcoholism.
164

Children's experience of epilepsy : a case study

Babane, Constance Vusiwana 30 November 2002 (has links)
This study focuses on the way in which learners living with epilepsy, who attend mainstream schools in the rural areas of the Limpopo Province, experience epilepsy. The results of the study indicate that the needs of learners with epilepsy are not well-catered for in mainstream schools. They often experience fear, anxiety, humiliation, ostracisation, name-calling, scape-goating, blaming and suspicion. Recommendations were made regarding the measures which should be taken to address the needs of rural children living with epilepsy. These recommendations could be used by teachers and the Department of Education. / Educational Studies / M.Ed. (Guidance and Councelling)
165

Atividade anticonvulsivante do óleo de peixe / Anticonvulsant activity of fish oil

Banderó, Cristina Ruedell Reschke 18 August 2010 (has links)
Conselho Nacional de Desenvolvimento Científico e Tecnológico / Methylmalonic acidemias are inherited metabolic disorders characterized by methylmalonate (MMA) accumulation and neurological dysfunction, including seizures. Dietary fatty acids are known as an important energy source and reduce seizure activity in selected acute animal models. This study investigates whether the chronic treatment with fish oil or with oleic acid attenuates MMA-induced seizures. Adult male Wistar rats were treated with fish oil (85 mg/kg), oleic acid (85 mg/kg) or vehicle (0.42 % aqueous Cremophor EL , 4 mL/kg/body weight/day), p.o., for 75 days. In the 73th day were implanted a cannula in the right lateral ventricle with electrodes over the parietal cortex for EEG recording. In the 76th day half the animals from each group were injected with NaCl (2.5 μmol/2.5 μL, i.c.v.), and the other half with MMA (2.5 μmol/2.5 μL, i.c.v.), and seizure activity was measured by EEG recording with concomitant behavior monitoring. The effect of prostaglandin E2 (PGE2) on Na+,K+-ATPase activity of slices of cerebral cortex from NaCl-injected (control) animals was determined. Fish oil administration increased the latency for MMA-induced tonic-clonic seizures and reduced the mean amplitude of ictal EEG recordings. Oleic acid decreased mean amplitude of ictal EEG recordings. Treatment with fish oil prevented PGE2-induced decrease of Na+,K+-ATPase activity in cortical slices in vitro. The results support a major anticonvulsant role for fish oil against MMA-induced seizures. The decreased sensitivity of Na+,K+-ATPase from fish oil-treated animals to the inhibitory effect of PGE2 may be related to its currently reported anticonvulsant activity. / A acidemia metilmalônica é um erro inato do metabolismo caracterizado pelo acúmulo tecidual de ácido metilmalônico (MMA) e disfunção neurológica, incluindo convulsões. Os ácidos graxos dietéticos são conhecidos como fonte de energia e reduzem a atividade convulsivante em determinados modelos experimentais agudos de convulsão. Este estudo investiga se o tratamento crônico com óleo de peixe ou com ácido oléico atenua as convulsões induzidas por MMA. Ratos Wistar machos adultos foram tratados com óleo de peixe (85 mg / kg), ácido oléico (85 mg / kg) ou veículo (solução aquosa de Cremophor EL® 0,42%, 4 mL / kg de peso corporal / dia), via oral, por 75 dias. No 73º dia foi implantada uma cânula no ventrículo lateral direito e dois eletrodos sobre o córtex parietal para o registro eletroencefalográfico. No 76º dia metade dos animais de cada grupo foi injetada com NaCl (2,5 Smol / 2,5 SL, i.c.v.), e outra metade com MMA (2,5 Smol / 2,5 SL, i.c.v.), e a atividade convulsiva foi medida por EEG e monitoramento comportamental concomitantemente. O efeito da prostaglandina E2 (PGE2) na atividade Na+, K+-ATPase foi determinada em fatias de córtex cerebral dos animais injetados com NaCl (controle). A administração de óleo de peixe aumentou a latência para as convulsões tônico-clônicas induzidas por MMA e reduziu a amplitude média dos registros ictais de EEG. O ácido oléico diminuiu a amplitude média dos registros ictais de EEG. O tratamento com óleo de peixe preveniu a diminuição da atividade da Na+, K+-ATPase induzida por PGE2 em fatias corticais in vitro. Os resultados suportam um papel importante anticonvulsivante do óleo de peixe sobre as convulsões induzidas por MMA. A prevenção da redução da Na+, K+-ATPase induzida por PGE2 nos animais tratados com óleo de peixe pode estar relacionada à sua atividade anticonvulsivante atualmente relatada.
166

A  apreensão no procedimento dos crimes contra a propriedade imaterial / Seizure in the procedure of immaterial property crimes

Pedro Ivo Gricoli Iokoi 23 May 2013 (has links)
À luz do princípio da presunção de inocência, construiu-se o entendimento de que no processo penal seriam lícitas apenas as medidas cautelares, em respeito ao status de inocência do acusado, vedando quaisquer outras medidas que revelassem uma antecipação do juízo condenatório. Partindo dessa premissa, as medidas de busca e apreensão passaram a ser entendidas e aceitas apenas como medidas cautelares, destinadas a assegurar a marcha processual ou a eficácia e a utilidade do provimento jurisdicional final. Entretanto, com a promulgação da Lei nº 10.695/2003 que modificou a proteção penal da propriedade imaterial e criou um novo procedimento especial para os crimes de ação penal de iniciativa pública , foi introduzida no sistema uma nova modalidade de apreensão, permitindo o apossamento de todos os bens ilicitamente produzidos ou reproduzidos, com o escopo de tornar o combate à pirataria mais eficiente. Assim, a nova medida deixou de ser um instrumento a serviço do processo e passou a ter um novo objetivo: dar resposta à sociedade com a apreensão, antes mesmo da produção da prova pericial, dos bens contrafeitos, revelando natureza jurídica de medida de antecipação de tutela (satisfativa). Entretanto, apesar de ter natureza jurídica satisfativa, a medida de apreensão prevista no artigo 530-B do Código de Processo Penal se justifica no nosso sistema e não representa violação ao princípio da presunção de inocência, por se referir a capítulo da sentença distinto do capítulo da autoria e da culpabilidade do acusado: refere-se ao capítulo das coisas que não podem ser restituídas. Nessa situação, tanto em casos de condenação quanto em casos de absolvição, impronúncia ou arquivamento, as coisas não podem ser restituídas porque o fabrico, a alienação, o porte ou a detenção constitui por si só fato ilícito autônomo. Logo, a antecipação de tutela determinando a apreensão de tais coisas não representa violação ao princípio da presunção de inocência. Por outro lado, o procedimento deve ser modificado para alcançar o justo equilíbrio entre a eficiência e o garantismo, introduzindo a obrigação de que a ilicitude seja constatada, por perito ou pessoa tecnicamente habilitada, logo após a apreensão e de que a medida seja sempre precedida de ordem judicial ou, nos casos de prisão em flagrante, seja imediatamente submetida à apreciação judicial, para que seja convalidada ou revogada / Under the light of assumption of innocence, it was understood that in the criminal suits there would only be acceptable caution measures regarding the status of innocence of the accused, prohibiting any other measures revealing an advanced position of the condemning judgment. As of this assumption, the search and seizure measures started to be understood and accepted only as caution measures, destined to assure the procedural progress or the effectiveness and usefulness of the final jurisdictional decision. However, with the enactment of Law 10695/2003 which modified the criminal protection of intangible property and created a new special process for criminal suits of public initiative a new kind of seizure was introduced, allowing the possession of all assets produced or reproduced illicitly, with the scope of rendering more efficient the fighting against piracy. Thus, the new measure stopped being an instrument to serve the suit and evidenced a new purpose, of providing answers to the society with the seizure of the infract assets, even before the production of the expert\'s evidence, revealing legal nature of advanced protection (satisfactory). However, in spite of having the legal nature of satisfaction, the seizure measure provided by article 530-B of the Criminal Procedures Code is justified in our system and does not represent infringement of the principle of assumption of innocence, since it refers to a chapter of the sentence different from the chapter of authorship and guilt of the accused, i.e., refers to chapter of things which cannot be returned. In these cases of things which cannot be returned, both in case of condemnation and acquittance, lack of judgment or filing, the things cannot be returned because the manufacture, disposal, possession or holding thereof, in itself, constitutes and independent illicit fact. Therefore, the advanced protection determining the seizure of such things does not represent infringement of the principle of assumption of innocence. On the other hand, the procedure must be modified to achieve fair balance between the efficiency and the guaranteeism, introducing the obligation of the forgery being evidenced by official expert or technically qualified person, straight after the seizure; and that the measure is always preceded by judicial order, or in cases of imprisonment in flagrant, that it is immediately submitted to judicial analysis, for the measure to be validated or revoked.
167

Titulação do limiar convulsígeno e segurança cardiovascular / Titration seizure threshold and cardiovascular safety

Celso Ricardo Bueno 13 November 2009 (has links)
A Eletroconvulsoterapia (ECT) é o tratamento biológico mais eficaz para quadros depressivos. Os estudos de seus aspectos técnicos são fundamentais tanto para compreensão dos mecanismos da ECT quanto para maximizar a eficácia e minimizar seus efeitos cognitivos. Existem muitos métodos para o cálculo da dose do estímulo elétrico e não há consenso em relação ao melhor. Sabe-se que doses muito elevadas tendem a ser eficazes, mas à custa de efeitos na memória. Embora o método de titulação seja recomendado pela Associação Psiquiátrica Americana, muitos profissionais tem preocupação sobre a segurança cardiovascular deste procedimento, devido aos sucessivos estímulos frustros que levam a um aumento na incidência de bradicardia e/ou assistolia. O objetivo deste trabalho foi traçar o perfil dos pacientes submetidos ao método da titulação do limiar, verificando sua segurança cardiovascular. Para isso foi feito um estudo retrospectivo e 113 casos foram revistos no ano de 2007. A maioria (70,3%) recebeu aplicação bilateral e (62,8%) eram mulheres. O diagnóstico de depressão apareceu com mais freqüência (50,5%). A maioria (57,5%) necessitou de dois estímulos, (12,4%) necessitou de apenas um, (28,3%) necessitou de três e (1,8%) realizou quatro estímulos. A média de frequência cardíaca inicial foi de 79,6 bpm (DP = 17). O limiar convulsígeno variou de 16mC a 128mC (média = 58,9; DP 25,4). A relação do limiar convulsígeno foi significativamente menor com o posicionamento unilateral dos eletrodos (p < 0,001), mas não com sexo ou idade. Não foi encontrada associação com a medicação concomitante. A incidência de bradicardia aumentou com os estímulos frustros, mas não foi significante a relação entre o primeiro e segundo estímulos. Não houve complicações cardíacas significativas e nenhum paciente apresentou assistolia. Conclui-se que o método da titulação do limiar pode ser uma estratégia segura e mais precisa, uma vez que os fatores (sexo, idade e uso de medicamentos) não foram relacionados com o LCT; a baixa incidência de complicações cardiovasculares reforça-o como método de escolha. Não se pode descartar um efeito protetor do uso da atropina. / Electroconvulsive therapy (ECT) is the most effective biological treatment for depression. Studies of the technical aspects are fundamental for understanding the mechanisms of ECT and to maximize efficiency and minimize their cognitive effects. There are many methods to determine the dose of electrical stimulation and there is no consensus on which is the best one. It is known that very high doses are effective, but at the expense of effects on memory. Although the method of limits (titration method) is generally accepted, being encouraged by the American Psychiatric Association, many practitioners have concerns regarding cardiac safety of this method. Due to repetitive subthreshold stimuli until the seizure is elicited, an increased risk of bradiarrhythmia and/or asystole is believed to be present. The objective of this study was to establish the profile of patients undergoing the method of titration of the threshold, checking their cardiovascular safety. A retrospective study was performed including 113 cases that receive their treatment in the year of 2007. The majority (70.3%%) received bilateral ECT, (62.8%) were women. The diagnosis of depression appeared more frequently (50.5%). The majority (57.5%) needed two stimuli; 12.4% needed only one; 28.3% needed three and 1.8% required four stimuli. The average initial heart rate was 79.6 bpm (SD = 17). The seizure threshold ranged from 16mC to 128mC (mean = 58.9, SD 25.4). The ratio seizure threshold was significantly lower with unilateral electrode placement (p <0.001) but not with sex or age. No association was found with concomitant medication. There was an increased incidence of bradycardia with subthreshold stimuli , but there was not a relationship between the first and second stimuli. There were no significant cardiac complications and no patient had asystole. In conclusion, the method of titration of the threshold seems to be a safe and more precise to determined electrical dose, since the factors usually used to predict the threshold (gender, age and medication use) were not related to the LCT The low incidence of cardiovascular complications adds up to its use as the method of choice.. A protective effect of atropine cannot be ruled out.
168

Epidemiologia de la epilepsia en el Peru : Neurocisticercosis como causa de epilepsia secundaria en la region norte del Peru / Epidémiologie de l'épilepsie au Pérou : Neurocysticercose comme cause de l'épilepsie secondaire dans la région nord du Pérou / Epidemiology of epilepsy : Neurocysticercosis as a strong contributor of symptomatic epilepsy in the northern region of Peru

Moyano Vidal, Luz Maria 22 September 2016 (has links)
Introduction. La neurocysticercosis (NCC) est l'un des maladies helminthiques les plus courantes du SNC et elle cause de l'épilepsie symptomatique dans les régions pauvres. Il existe peu d'études communautaires sur cette zoonose et leurs comorbidités comme l'épilepsie et la NCC. Méthodologie. Dans la région nord du Pérou, trois études sur la communauté et une révision systématique ont été développés dont les objectifs étaient les suivants: a) évaluer la prévalence de la NCC asymptomatique, b) la prévalence de l'épilepsie associée à la cysticercose, c) la détermination de l'exposition à la cysticercose d) développer une intervention communautaire pour interrompre la transmission de la cysticercose. Résultats. 256 patients asymptomatiques qui avaient une tomodensitométrie (T) sans contraste, 48 (18%) avaient la NCC calcifiés. La prévalence de l'épilepsie trouvée était de 17.25 / 1000 habitants et la proportion de NCC en personnes atteintes d'épilepsie était de 39% (109/282). Le Western Blot (EITB-LLGP) pour la cysticercose a été positive dans le 40% des personnes atteintes d'épilepsie, et dans le 36,9% de la population générale. L'association entre la cysticercose et l'épilepsie avait un OR de 2,7 (95% CI 2.1 – 3.6, p <0,001). Le traitement massif avec niclosamide chez l'homme (n = 3), et plus la vaccination de la population porcine a été mis en oeuvre dans 107 communautés rurales de Tumbes. Aucun porc infecté avec la cysticercose n’a été trouvé en 105 des 107 communautés. Conclusions. (1) La NCC est un facteur contributeur de l'épilepsie, (2) La transmission de T. solium peut être réduite à échelle régionale. / Backgrounds. Neurocysticercosis is a parasitic infection of the brain and a common cause of epilepsy in poor regions. There are scarce community-based studies about its comorbidities as epilepsy and neurocysticercosis. Methods. In the northern region of Peru, we performed three community based-studies and one systematic review a) to assess the prevalence of asymptomatic NCC, b) the prevalence of epilepsy and epileptic seizures and NCC c) seroprevalence of cysticercosis (EITB-LLGP) and d) to perform a community intervention to interrupt the Taenia solium transmission. Results. Of the 256 residents who underwent CT scan, 48 (18.8%) had brain calcifications consistent with NCC. Lifetime prevalence of epilepsy was 17.25/1000, the proportion of NCC in people with epilepsy was 39% (109/282), and the seroprevalence of EITB-LLGP in individuals with epilepsy was 40% and between 23.4 to 36.9% in the general population. The association between CC and epilepsy had a OR of 2.7 (95% CI 2.1-3.6, p <0.001). Three rounds of mass treatment with niclosamida in humans and mass treatment and vaccination in pigs was implemented in 107 rural communities (n=81,170 people). No infected pigs with cysticercosis were found in 105 of 107 communities. Conclusion. NCC is a strong contributor of epilepsy and epileptic seizures. We showed that transmission of Taenia solium infection was interrupted on a regional scale in endemic regions in Peru / Introducción. La neurocisticercosis (NCC) es una de las enfermedades helmínticas más frecuentes del SNC y causa de epilepsia sintomática en regiones pobres. Hay escasos estudios basados en comunidad sobre esta zoonosis y sus comorbilidades la epilepsia y la NCC. Metodología. Se desarrollaron en la Región Norte del Perú tres estudios basados en la comunidad, y una revisión sistemática cuyos objetivos fueron: a) evaluar la prevalencia de NCC asintomática, b) la prevalencia de epilepsia asociada a cisticercosis, c) determinación de la exposición a cisticercosis y d) desarrollar una intervención comunitaria que interrumpa la transmisión de cisticercosis. Resultados. De 256 pacientes asintomáticos que tuvieron una tomografía axial computarizada (TAC) cerebral sin contraste, 48 (18%) tuvo una NCC calcificada. La prevalencia de epilepsia encontrada fue de 17.25/1000 habitantes y la proporción de NCC en personas con epilepsia fue de 39% (109/282). El Western Blot (EITB-LLGP) para cisticercosis fue positivo en el 40% de los individuos con epilepsia, y en el 36.9% de la población general. La asociación entre cisticercosis y epilepsia tuvo un OR de 2.7 (95% CI 2.1-3.6, p <0.001). El tratamiento masivo con niclosamida en humanos (n=3), y población porcina más vacunación fue implementada en 107 comunidades rurales de Tumbes; en 105 de 107 no hubo nuevos cerdos infectados con cisticercosis. Conclusiones. (1) La NCC es un factor contribuidor de epilepsia, (2) Se puede cortar la trasmisión de T. solium a escala regional.
169

The Role of the Neuronal gap Junction Protein Connexin36 in Kainic Acid Induced Hippocampal Excitotoxicity

Akins, Mark S. January 2014 (has links)
Kainic acid induced excitotoxicity causes pyramidal cell death in the CA3a/b region of the hippocampus. Electrical synapses, gap junctional communication, and single membrane channels in non-junctional membranes (hemichannels) composed of connexin36 (Cx36) have been implicated in both seizure propagation and the spread of excitotoxic cell death. In rats, Cx36 protein is expressed by pyramidal neurons. Localization of protein in mouse, however, is highly controversial. Expression is reported to be restricted to hippocampal interneurons yet the same excitotoxic mechanisms (electrical and metabolic coupling between pyramidal neurons) are invoked to explain the role of Cx36 in excitotoxic pyramidal loss in murine brain. To address this controversy, I show by confocal immunofluorescence and in situ hybridization that Cx36 protein expression is restricted to interneurons and microglia in murine hippocampus and is not expressed by, or is below level of detection in pyramidal neurons. Using behavioural and electrophysiological measures, seizure propagation was found to be moderately enhanced in the absence of Cx36 likely due to the loss of interneuron-mediated synchronous inhibition of the pyramidal cells. Further, CA3a/b neurons die post kainic acid injury in the presence of Cx36 but are protected in Cx36-/- mice. When delayed excitotoxic cell death is maximal, Cx36 is primarily expressed by activated microglia as demonstrated by confocal immunofluorescence, in situ hybridization, and Western blotting. These activated microglia are located in the direct vicinity of, and surrounding cells in the damaged Ca3a/b region. Finally, I show that loss of Cx36 from activated microglia in mice is sufficient to prevent excitotoxic cell death in the CA3a/b with surviving neurons functional as assessed by both electrophysiological and behavioural measures. Together, these data identify a new mechanism of excitotoxic injury, mediated by neuronal-glial interactions, and dependent on microglial Cx36 expression.
170

Hur förstår du dina funktionella anfall? : En kvalitativ intervjustudie / How do you understand your functional seizures? : A qualitative interview study

Ljungdahl, Malin January 2020 (has links)
Inledning: Funktionella anfall, anfall som inte är epilepsi utan tros ha en psykologisk orsak, kan mötas av oförståelse också inom sjukvården. För att förstå detta tillstånd behöver man en processinriktad biopsykosocial sjukdomsmodell där patientens egen sjukdomsförståelse är en viktig del. Frågeställningar: Hur upplever patienter med funktionella anfall sin sjukdom?Hur förstår patienter med funktionella anfall sin sjukdom? Metod: Fem fenomenologiska halvstrukturerade intervjuer har genomförts och med hjälp av tematisk analys kondenserats till fyra teman. Resultat: De fyra temana är upplevelsen av anfallen, egen förståelse av anfallen, konsekvenser av anfallen och vad hjälper mot anfallen. Stora skillnader framkommer i intervjupersonernas upplevelse och förståelse av sina anfall. Anfallen upplevs som en känsla av förändrad kontakt eller ingen kontakt mellan kropp och hjärna och de beskrivs både begränsa och berika livet. Sjukdomsförståelsen uttrycks i fysiologiska termer, i mer vaga psykologiska termer eller att det inte går att förstå. Det framkommer tveksamhet till om psykologisk behandling hjälper. Diskussion: Det diskuteras att de funktionella anfallen faktiskt går att förstå, ibland medvetet och ibland omedvetet som en försvarsmekanism enligt psykodynamisk modell. Korttids psykodynamisk terapi såsom ISTDP kan därför vara ett behandlingsalternativ när psykoedukation och KBT inte har varit tillräckligt. / Introduction: Functional seizures, seizures that are believed to have a psychological cause, may face misunderstanding also in health care. To understand this condition, one needs a process-oriented biopsychosocial model in which the patient's own experience of illness is an important part. Questions: How do patients with functional seizures experience their illness?How do patients with functional seizures understand their illness? Method: Five phenomenological semi-structured interviews have been conducted and condensed into four themes using thematic analysis. Results: The four themes are experience of the seizures, understanding of the seizures, consequences of the seizures and what helps against the seizures. Large differences emerge in the interviewees' experience and understanding of their seizures. The seizures are experienced as a feeling of altered contact or no contact between body and brain and they are described to both limit and enrich life. Understanding of illness is expressed in physiological terms, in more vague psychological terms or cannot be understood. There is some doubt as to whether psychological treatment will help. Discussion: It is discussed that the functional seizures can actually be understood, sometimes consciously and sometimes unconsciously as a defense mechanism according to the psychodynamic model. Therefore, short-term psychodynamic therapy such as ISTDP may be a treatment alternative when psychoeducation and CBT have not been sufficient.

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