L'efficacité de la transmission synaptique GABAergique est influencée par la concentration intracellulaire en ions chlorure. Dans les neurones matures, l'extrusion de ces ions par le transporteur neuronal potassium chlore de type 2 (KCC2) permet l'influx d'ions chlorure lors de l'activation des récepteurs du GABA de type A. Néanmoins, KCC2 est aussi enrichi à proximité des synapses excitatrices portées par les épines dendritiques qui correspondent à des protrusions dendritiques enrichies en actine. Alors que l'effet d'une suppression de KCC2 sur l'homéostasie des ions chlorure et la transmission GABAergique est largement documenté, peu de choses sont connues sur l'impact qu'une telle suppression peut avoir sur la transmission glutamatergique. Lors de ma thèse, j'ai exploré le rôle de KCC2 dans la potentialisation à long terme (LTP) de la transmission glutamatergique à l'origine des phénomènes d'apprentissage et de mémorisation. Ce travail a révélé que la suppression de KCC2 compromet les modifications fonctionnelles et structurales sous-tendant la LTP. Cet effet est associé à une inhibition de la cofilin, protéine responsable de la dépolymérisation de l'actine, qui corrèle avec une augmentation de la quantité d'actine filamenteuse dans les épines dendritiques. En empêchant l'inhibition de la cofilin liée à l'absence de KCC2, il m'a alors été possible de restaurer la LTP suggérant que KCC2 pourrait influencer cette forme de plasticité en régulant la dynamique de polymérisation du cytosquelette d'actine. Mes résultats démontrent que la fonction de KCC2 va au-delà du contrôle de l'homéostasie des ions chlorure et influence les mécanismes de plasticité de la synapse excitatrice. / The polarity and efficacy of GABAergic synaptic transmission are both influenced by the intra-neuronal chloride concentration. In mature neurons, chloride extrusion through the neuronal K/Cl cotransporter KCC2 allows an inhibitory influx of chloride upon activation of GABAA receptors. Nevertheless, KCC2 is enriched in the vicinity of excitatory synapses within the dendritic spines that are actin-rich protrusions emerging from dendritic shafts. While it has become clear that KCC2 suppression alters chloride homeostasis and GABA signaling, little is known on its impact on glutamatergic transmission. In the laboratory, we have previously demonstrated that KCC2 suppression in mature neurons leads to decreased glutamatergic transmission efficacy through an ion-transport independent function of KCC2. During my PhD, I have explored how KCC2 may also impact LTP of glutamatergic synapses. My work reveals that KCC2 suppression compromises both functional and structural LTP at these synapses. This effect is associated with inhibition of the actin-severing protein cofilin and enhanced mobilization of F-actin in dendritic spines. Since LTP can be rescued by preventing cofilin inhibition upon KCC2 suppression, I suggest KCC2 might influence LTP through altered actin cytoskeleton dynamics. My results demonstrate that KCC2 function extends beyond the mere control of neuronal chloride homoeostasis and suggest regulation of KCC2 membrane stability may act as a metaplastic switch to gate long term plasticity at excitatory synapses in cortical neurons.

Foram avaliados 25 cães portadores de discopatia cervical aos exames radiográficos simples, mielografia e tomografia computadorizada. A dor foi o principal sinal clínico em 64% dos casos. Os animais com raça definida foram os mais acometidos (85%), tendo maior incidência da raça Teckel. A faixa etária mais acometida foi entre 7-9 anos (72%). O exame radiográfico simples indicou aspectos compatíveis com extrusão em 14 observações. A mielografia diagnosticou 15 extrusões, 18 protrusões e 4 hérnias de disco e forneceu informações quanto ao grau de compressão medular e extensão das lesões. A tomografia computadorizada (TC) indicou 16 extrusões, 22 protrusões e 3 hérnias de disco. O espaço de C2-3 foi o mais acometido. A TC permitiu o diagnóstico de extrusões calcificadas, mesmo na presença de pouca quantidade ou ausência de meio de contraste e indicou com precisão o grau de compressão medular, a extensão e principalmente, a localização das lesões. Concluiu-se com este estudo que os três exames se complementam e constituem importantes ferramentas para o planejamento clínico-cirúrgico. / Twenty-five dogs with disc disease in cervical spine were evaluated by radiological and computed tomographic exams. The most common clinical signs were neck pain present in 64% of the dogs. Of the animals 85% were pure breed, amongst them Teckel were most frequent (28%). The most cases occurred in animals between seven and nine years. C2-3 was the preferred site of cervical involvement. Radiographic plain indicated fourteen extrusion. Myelography demonstrated fifteen extrusions, eighteen protrusions and four disc hernias and indicated spinal cord grade compression and lesions extension. Computed tomographic (CT) demonstred sixteen extrusions, twenty-two protrusions and three disc hernias. The CT showed to be more sensitive for soft tissue calcification, and his superior contrast resolution allowed visualization small quantities of contrast material in the subarachnoid space and indicated with precision the site and extension of lesions as well as the degree of spinal cord compression. The three exams are complementary and give valuable information for clinical and chirurgical procedures.

La scoliose est une déformation en trois dimensions de la colonne vertérbale. Les traitements chirurgicaux actuels sont à l’origine d’une perte de mobilité et de croissance du rachis. Pour palier à ces difficultés, un implant innovant de correction à été développé. Cet implant de type « fusionless » a pour but de préserver la mobilité et la croissance de la colonne vertébrale. Des études morphométriques nous ont permis de connaître la croissance du rachis chez le porc. Cette dernière est maximale entre la 6ème et la 10ème semaine de vie. Les corridors d’insertion des vis pédiculaires ont également pu être décrit. Ensuite, des essais biomécaniques nous ont permis de connaître les contraintes s’exerçant sur le rachis du porc au cours de l’apparition des déformations scoliotiques et de décrire la résistance à l’arrachement des vis pédicualires. Chez le porcs, leur implantation doit etre bicorticale. Enfin, le dispositif a pu être implanté avec succès et a été suivi pendant 2 mois chez 6 porcs charcutiers. Nous avons pu montrer que le dispositif ne semble altérer ni la croissance ni la mobilité rachidienne. Aucune dégénérescence discale n’a été observée / Scoliosis is a three-dimensional deformity of the spine. Current surgical treatment are associated with a lost of spine mobility and growth. To avoid those complications, a new fusionless device, preserving spine growth and mobility, has been develloped. Morphometrics studies allow us to evaluated spinal growth in the pigs. This latter one is maximal between the 6th and 10th weeks. Safe corridor of implantation of pedicle screws was also described. During biomechanicals studies, in vivo measurements of forces observed pigs during soliosis deformities induction in a porcine model was performed. Pullout ressitance of pedicle screw in pigs verterbra was also measured in ordre to optimize pedicle screw fixation in the porcine model. In growing pigs, bicortical screw implantation should be used.Finally, the device was implanted during two months in 6 pigs. Spine growth and mobility were not affected and no disc degeneration was observed during the follow up period

Minimally invasive spine surgery (MISS) has proven to be advantageous over traditional open surgery as it minimizes the likelihood of tissue damage and infections. During MISS, surgeons create small incisions to allow access to the surgery site, however, opting for smaller incisions decreases the surgeon’s field of vision. To compensate, surgeons rely on preoperative and intraoperative ionizing imaging technologies for guidance. Conventional localization of the spine, registration of digital images to the patient during surgery, depends heavily on the surgeon’s anatomical knowledge and their experience. Preoperative images are typically created using 3D technology while intraoperative images use 2D technology. While the integration of preoperative 3D images and intraoperative 2D images can provide valuable assistance, patient’s preoperative and intraoperative positions do not coincide leading to additional use of ionizing imaging. The objective of this research was to propose a workflow that assists with image registration for MISS. The main component of the workflow was the creation of a script that automatically generates patient-specific digital guides, which will then be manufactured, to align the patient’s intraoperative and preoperative body position. By aligning the patient’s positions, the 3D printed surgical guide serves as a shared feature between the preoperative digital image and the actual patient. This allows for the intraoperative image to be registered to the preoperative image more accurately. Additionally, the guide acts as an attachment site for any additional instrument guides/supports. The surgical guide generating script utilizes the skin contour of patient’s torso region, extracted from medical images, to automatically produce the guide’s horizontal and vertical components. Adjustments are made to the components using CAD software before proceeding to manufacturing, via 3D printing, and assembly of the guide. To validate the workflow, more specifically the script’s ability to automatically generate surgical guides that fit over the patient’s back, a guide was created for a mannequin. The maximum gap between the mannequin and the horizontal components was 0.8 cm and 1.5 cm for the vertical component.

This Master’s thesis deals with strain-stress analysis of a spine segment with an introduced fixator and a spine in natural physiological state. The work starts with a research study of literature sources that focus on similar issues. Furthermore, basic anatomy terminology and basic procedures for human spine stabilization were described. The formulated issue was resolved by computational modelling with the use of the finite element method. This solution requires a suitable computational model to be produced. This model consists of partial geometry, material, bond, and loading models. The geometric model was produced on the basis of CT scan images of a 60-year-old man which were used for producing five spine vertebrae T11–L3. Moreover, the geometric model consists of four intervertebral discs and eight articular cartilages. The material model includes homogeneous, heterogeneous and degraded properties of bone tissue. The strain-stress analysis was performed for seven loading states, which concern basic movements of human spine – standing, bending forward, bending backwards, bending left, bending right, left rotation and right rotation, with the use of ANSYS software. The assessed and analysed quantities include spine segment displacement, contact pressure of articular cartilages and stress on the fixator.

The diploma thesis describes the design of curved, pre-stressed concrete bridge over the highway D1. A variant, that is chosen for detail analysis, is a spine girder construction as a continuous beam with 3 spans. The thesis solves the construction to limit states according to applicable European standards (Eurocodes). There are developed clear and detailed drawings and visualization of the bridge.

Orientador: Guilherme Antonio Moreira de Barros / Resumo: Segundo a Associação Internacional para o Estudo da Dor (IASP), a dor crônica pós-operatória (DCP) é aquela presente por mais de três meses após a realização de um procedimento cirúrgico. As cirurgias ortopédicas para o tratamento de doenças degenerativas relacionadas ao avanço da idade têm crescido nas últimas décadas, expondo esses indivíduos ao risco de desenvolver a DCP. O objetivo desse estudo foi avaliar a incidência de DCP em pacientes submetidos as cirurgias ortopédicas como a artroplastia total de joelho e quadril, fixação de fratura de fêmur e cirurgias na coluna vertebral. Os fatores de associação para o aparecimento da DCP, assim como sua ocorrência foram estudados. Foram aplicados questionários validados disponíveis na literatura, assim como protocolo de pesquisa desenvolvido pelos pesquisadores. Buscou-se contemplar questões sobre a presença, localização, tipo e intensidade da dor, presença de dor neuropática, identificação de labilidade emocional e catastrofização da dor, uso de medicação para o controle da dor, dentre outros. As entrevistas dos participantes ocorreram em duas etapas, no pré-operatório e pós-operatório, esse último com o seguinte cronograma: 30 dias, três, seis e doze meses após a realização da cirurgia. Os pacientes incluídos no decorrer da pesquisa foram acompanhados durante um ano após a realização da cirurgia, sendo assim, o estudo levou dois anos para ser concluído. Essa pesquisa foi aprovada pelo Comitê de Ética em Pesquisa da instituição... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: According to the International Association for the Study of Pain (IASP), chronic postoperative pain (DCP) is that present for more than three months after the performance of a surgical procedure. Orthopedic surgeries for the treatment of degenerative diseases related to advancing age have grown in recent decades, exposing these individuals to the risk of developing PCD. The aim of this study was to evaluate the incidence of PCD in patients undergoing orthopedic surgeries such as total knee and hip arthroplasty, fixation of the femur fracture and surgeries in the spine. The association factors for the onset of DCP, as well as its occurrence, have been studied. Methods: Validated questionnaires available in the literature were applied, as well as a research protocol developed by the researchers. We sought to contemplate questions about the presence, location, type and intensity of pain, presence of neuropathic pain, identification of emotional lability and pain catastrophization, use of medication for pain control, among others. The participants' interviews took place in two stages, in the preoperative and postoperative periods, the latter with the following schedule: 30 days, three, six and twelve months after the surgery. The patients included in the research were followed up for one year after the surgery, so the study took two years to complete. This research was approved by the institution's Research Ethics Committee. Results: After invitation, analysis of inclusion and ex... (Complete abstract click electronic access below) / Doutor

Sensory, cognitive, and emotional processing are rooted in the cerebral cortex. The cerebral cortex is comprised of six layers defined by the neurons within them that have distinctive connection, both within cortex itself and with other subcortical structures. Although still far from solving the mysteries of the mind, it is clear that networks form by neurons in the cerebral cortex provide the computational substrate for a remarkable range of behaviours. This neuron to neuron activation is mediated through dendritic spines, the postsynaptic target of most excitatory synapses in the cerebral cortex. Dendritic spines are small protrusions found along dendrites of neurons, and their number, as well as structural changes, accompany the development of synapses and establishment of neuronal networks. In fact, dendritic spines undergo rapid structural and functional changes guided by neuronal activity. This marriage between structural and functional plasticity, makes dendritic spines crucial in fine-tuning of networks in the brain; not surprisingly, dendritic spine aberrations are a hallmark of multiple neurodevelopmental, neuropsychiatric, and neurodegenerative disorders. With this in mind, I considered Pannexin 1 (Panx1) an interesting novel candidate for a regulatory role on cortical neuronal network and dendritic spine development, for the following reasons. First, Panx1 transcripts are enriched in the brain and in the cortex are most abundant during the embryonic and early postnatal period. . This timing roughly corresponds to a period of synaptogenesis in the postnatal brain. Second, Panx1 localizes to postsynaptic compartments in neurons and its disruption leads to enhance excitability and potentiation of neuron-to neuron communication. Third, disruption of Panx1 (either knockdown or pharmacological blockade) leads to neurite outgrowth in neuron-like cells. Lastly, genetic variants in PANX1 have been associated with neurodevelopmental disorders. This dissertation explores the role of Panx1 in the development of dendritic spines and neuronal networks, furthering our understanding on cortical development and placing Panx1 as a novel regulator of structural and functional plasticity in the brain. Chapter 1 discusses core concepts on cortical development, with an emphasis on pyramidal neuron, the most abundant and only known projection neurons in the cerebral cortex. Here, I review the embryonic origin of pyramidal neurons, their postnasal development, and how cortical circuits are assembled. I finish this chapter with a brief review on Panx1 and its known expression and involvement in neuronal function. In Chapter 2 I explore the functional properties of neuronal networks and synaptic composition of cortical neurons in the absence of Panx1. Using live cell imaging and analysis of Ca2+ transients in dense primary cortical cultures, revealed that Panx1 knock-out (KO) cultures exhibit more and larger groups of significantly co-activated neurons, known as network ensembles. These network properties were not explained by differences in cell viability or cell-type composition. Examination of protein expression from cortical synaptosome preparations revealed that Panx1 is enriched in synaptic compartments, while also confirming a developmental downregulation. This analysis also revealed increased levels of the postsynaptic scaffolding protein PSD-95, along with the postsynaptic glutamate receptors GluA1 and GluN2A. Lastly, ex vivo tracing of dendritic spines on apical dendrites of Layer 5 pyramidal neurons in global and glutamatergic-specific Panx1 KO brain slices revealed higher spine densities in early and late postnatal development, with no differences in spine length. Analysis of dendritic spine densities in fixed cultured cortical neurons revealed an increase associated with Panx1 KO. Altogether, this work presents for the first time a connection between Panx1 and structural development of dendritic spines and suggest that Panx1 regulates cortical neuronal networks through changes in spine density. Chapter 3 examines the influence of Panx1 on spiny protrusions growth and movement. Spiny protrusion are long, thin, highly dynamic spine precursors. Taking advantage of a fluorescent signal localized to the plasma membrane, I visualized spiny protrusions and quantified their dynamics in wildtype (WT) and Panx1 KO developing cortical neurons, both under fixed and live conditions. I found that transient Panx1 expression is associated with decreased spiny protrusion density both in WT and Panx1 KO neurons. Using live cell imaging, I found that spiny protrusions are more stable and less motile in Panx1 KO neurons, while its transient expression reversed both of these phenotypes. These results suggest that Panx1 regulation of dendritic spines development is rooted partly in the regulation of spiny protrusion dynamics. Overall, this dissertation demonstrates that Panx1 negatively regulates dendritic spines in part by influencing spiny protrusion dynamics. It is reasonable to speculate that Panx1 regulation of dendritic spines underlies its newly discovered role in the formation network ensembles, providing a putative mechanism for previously described roles of Panx1 in synaptic plasticity. Likewise, this body of work furthers our understanding of Panx1 by filling some of the gaps attached to its developmental expression and association with neurodevelopmental disease. / Graduate / 2021-04-16

Up to date, only four cases of primary intradural extramedullary spinal cord melanoma (PIEM) have been reported. No previous reports have described a case of PIEM located in the lower thoracic spine with long-termfollow-up. Purpose. Demonstrating an unusual, extremely rare case of melanoma manifestation. Study Design. Case report. Methods. We report a case of a 57-year-old female suffering from increasing lower extremity pain, left-sided paresis, and paraesthesia due to spinal cord compression caused by PIEM in the lower thoracic spine. Results. Extensive investigation excluded other possible primary melanoma sites and metastases. For spinal cord decompression, the tumor at level T12 was resected, yet incompletely. Adjuvant radiotherapy was administered two weeks after surgery. The patient was recurrence-free at 104 weeks after radiotherapy but presents with unchanged neurological symptoms. Conclusion. Primary intradural extramedullary melanoma (PIEM) is extremely rare and its clinical course is unpredictable.

Thesis Title: The Quantification of Biomechanical Consequences of Monotonous Sedentary Work to the Axial System Thesis Goals: The goal of the Diploma Thesis is to assess the impact of sedentary work position on the axial system and to find out what changes in biomechanical properties occur specifically in the spine after the specific monotonous eight hours lasting load. Method: Five probands were exposed to diagnostic vibrations of the TVS method (transfer vibration through the spine) before performing eight hours monotonous sedentary work and after it. The examined feature was the ability of the axial system to dampen vibrations spread throughout the spine. Dampening reactions of individual segments were compared to each other before and after the performance of work. Results: The TVS method applied at work has proven its adequacy in the provision of information on resonance frequencies and on the overall attenuation of the spine with sufficient accuracy so that the impact to the axial system after completing the work performance was clearly identifiable. When comparing the frequency dependence and overall attenuation of individual probands we have found that the overall attenuation of the spine increased in all examined individuals. Key words: work, axial system, spine, vibrations and TVS.