Thesis (M.Ost.)--Unitec New Zealand, 2008. / Includes bibliographical references (leaves 75-83).

Thesis (M.S.)--University of Michigan, 1984.

Thesis (M.S.)--University of Wisconsin-Madison. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 63-67).

No description available.

During amniote embryogenesis, the segmented pattern characteristic of the vertebral column appears early during development through the sequential formation of multipotent structures called somites. Somites differentiate subsequently into dermomyotome (giving rise later to skin and skeletal muscles) and sclerotome (giving rise to vertebral bone structures and cartilage). In addition, sclerotomes subdivide following their rostro-caudal intrasegmental boundary into an axon growth-permissive region (anterior half) and an axon growth-repulsive region (posterior half). This binary system instructs motor and sensory axon navigation, as well as neural crest cell migration, to ensure that the peripheral nervous system develops without obstruction by the future cartilage and bones of the vertebral column. Repellent cues are expressed in posterior half-sclerotomes in order to exclude navigating axons from “no-go” areas and restrict their growth to specific exit points of the future vertebral column. Interestingly, similar repellent cues (e.g. Eph/Ephrins) are expressed in the adult central nervous system (CNS) and have been shown to control connectivity and plasticity throughout life. Following brain or spinal cord injury, these repellent molecules are upregulated by reactive astrocytes accumulating at the lesion site, and may impede axon regeneration in this region. In this dissertation, I am presenting the results of a differential gene expression analysis of anterior and posterior half-sclerotomes, based on RNA-sequencing data and using the chick embryo as a model organism. This study led to the identification of molecules, previously uncharacterized in this system, that may play a role in adhesive and mechanical properties of somites and in axon guidance and fasciculation. I focused on the functional analysis of one molecule of the posterior half-sclerotome, the extracellular matrix protein Fibulin-2. To look at its role in the segmentation of spinal axons, I used ectopic misexpression in a subset of segments based on somite electroporation. The width of spinal nerve bundle growth was restricted by Fibulin-2 overexpression in posterior and anterior half-sclerotomes, suggesting a role in sharpening/controlling the path of spinal axon growth. In addition, I showed that this could occur via an interaction with the axon growth repellent Semaphorin 3A. Then I looked at the expression of Fibulin-2 in two models of CNS injury: mouse cerebral cortical stab injury and rat dorsal crush spinal cord injury. In both cases, I observed an increase in Fibulin-2 protein level compared to control. I also used primary cultures of rat cortical astrocytes to show that the expression of Fibulin-2 after inflammatory cytokine-induced activation is increased. Finally, I studied a candidate axon growth repellent previously identified in the laboratory. I explored the hypothesis that this repellent molecule is an O-glycosylated, spliced variant form of a known protein. To characterize this repellent molecule, I used RNA-sequencing data from chick embryonic somites and 2D gel electrophoresis of an astrocytic cell line protein extract. Together, these results suggested that the developing vertebral column and the adult CNS share molecular features to control axon growth and plasticity. This type of study could lead to the characterization of molecular systems that regulate axon growth, and to the identification of novel therapeutic targets in brain or spinal cord injury.

La posture, composante statique du contrôle moteur permettant une position érigée du corps, repose sur une décharge tonique des motoneurones innervant nos muscles antigravitaires. La décharge prend la forme de « potentiel de plateau » au niveau de motoneurones matures chez de nombreux vertébrés. Pour déterminer une éventuelle concordance entre l'émergence des propriétés de plateau et le développement postural, notre travail a eu pour but d'étudier la maturation et la nature ionique des potentiels de plateau des motoneurones innervant le muscle triceps surae (extenseur de la cheville) chez le rat nouveau-né.La réalisation de ces travaux de thèse nous a permis de dégager un mécanisme fondamental dans la genèse des propriétés de plateau des motoneurones lombaires. Ce mécanisme dont le fondement repose sur l'activation d'un « ménage à trois » jouerait un rôle majeur dans le développement moteur chez le rat. Dans la mesure où les potentiels de plateau des motoneurones sont fortement perturbés à la suite d'une lésion médullaire, cette avancée scientifique permettra éventuellement de mieux comprendre l'origine de certains déficits sensori-moteurs (spasticité, hyperalgésie...) et le développement de nouvelles stratégies thérapeutiques. / Posture allowing an erect posture of the body relies on spiking activity of motoneurons innervating antigravitary muscle. Discharge could take the form of plateau potential on mature motoneurons of numerous vertebrates. To determine a possible concordance between the emergence of plateau potential and postural control development, we studied the maturation and ionic nature of plateau potential of motoneurons innervating triceps surae muscle of neonatal rat.The conclusion of our work allows us to propose a fundamental mechanism in the genesis of plateau potential on lumbar motoneurons. This mechanism based on a "ménage a trois" seems to play an important role in the neonatal motor development. This scientific advance could eventually lead to a better understanding of the origin of some sensori-motor impairments (spasticity, hyperalgesia...) and development of therapeutic strategies.

This study aims to explore, and to a certain extent to clarify, what it means psychologically to experience Traumatic spinal cord injury (TSCI) in a South African spinal unit. The target time chosen for analysis is the acute medical period. The study presents a review of the literature on psychological adjustment to TSCI and then proceeds to introduce and extensively articulate the hermeneutic approach and methodology. Subsequently, an interpretive research strategy is presented for the purpose of studying the acute phase of TSCI. The data for the study was obtained by means of three dialogical interviews which were tape recorded, transcribed and analyzed with~n a cyclical framework consisting of three interdependent levels. The interpretive procedure is modeled upon the 'reading guide' developed by Brown, Tappan, Gilligan, Miller and Argyris (1989). The analysis follows a course from the individual psychological descriptions of the experience to the generation of a general, nomothetic narrative account of the acute phase. The findings are then discussed in relation to the existing literature and evaluated on the basis of the goals of the study. The study highlights the value of some of the 'stage' ways of thinking about SCI adjustment, while simultaneously stressing the need for placing adjustment within a more personalized, and individually meaningful context. Significant differences between the psycho-physical experiences of patients in the categories of complete and -incomplete SCI were found, which suggests that a sharper distinction be made in the literature between these two groups, in order to account for the marked variations in their experiences.-- The study also contains a number of shortcomings, such as a lack of understanding about certain historical and contextual factors which may have mediated the experiences of the trauma for the individuals concerned. These shortcomings and some suggestions fro their resolution are then discussed. The study concludes with an evaluation of the research strategy and methodology and also offers some suggestions for future research.

Orientador: Yvens Barbosa Fernandes / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-19T18:49:05Z (GMT). No. of bitstreams: 1 Cavalcante_RodrigoAlvesdeCarvalho_M.pdf: 47962870 bytes, checksum: 30187744bcc8d761f23631f51a4d472c (MD5) Previous issue date: 2012 / Resumo: Fraturas da coluna tóraco-lombar tem alta prevalência em todo mundo e, portanto, exige dos cirurgiões de coluna uma constante tomada de condutas no sentido de propor a melhor forma de tratamento para os doentes acometidos com essas fraturas. A melhor forma de tratar as mesmas seria então tentar agrupá-las, classificá-las e a definir a presença ou não de instabilidade, definindo uma conduta de tratamento clínico ou cirúrgico. Dentre os vários sistemas de classificações existentes para classificar essas fraturas, os mais utilizados na atualidade são o Thoracolumbar Injury Classification System (TLICS) escore e sistema de Classificação da ArbeitgemeinschaftOsteosynthesefragen (AO). Nesse estudo foi utilizado o escore TLICS recentemente publicado para avaliar retrospectivamente 49 doentes tratados cirurgicamente entre 2003 a 2009 no Hospital das Clínicas da Unicamp e no Hospital Dr. Mário Gatti em Campinas-SP, por fraturas em coluna tóraco-lombar. O TLICS recomendou tratamento em 47 de 49 pacientes operados (96%), sendo identificada correlação estatística significante do mesmo, com o sistema de classificação AO (p= 0.0088), com status neurológico( p=0.001) e a correlação da classificação AO com status neurológico( p=0.041), utilizando o teste de Fischer. Os resultados do presente estudo permitem concluir que esse escore é acurado para predizer a conduta cirúrgica no tratamento dessas lesões / Abstract: Fractures of the thoracic and lumbar spine have a high prevalence worldwide, therefore, requires the spine surgeons conduct a continuous decision to propose the best treatment for patients affected with these fractures. The best way to treat the same would then try to group and classify them and after that define its stability or instability, a defining conduct of clinical or surgical treatment. Among the various classification systems exist to classify these fracture, the most frequently used are TLICS score and Arbeitgemeinschaft fur Osteosynthesefragen (AO) classification system. We used the recently published TLICS score to evaluate retrospectively 49 patients treated surgically between 2003 to 2009 at the Hospital of UNICAMP and Dr. Mário Gatti Hospital in Campinas-SP, for fractures at the thoracolumbar spine. The TLICS score recommended treatment in 47 of 49 operated patients (96%), being identified a significance statistical analysis correlation between the same with the AO classification system (p=0.0088), the TLICS score and neurological status (p=0.001) and the AO classification system and neurological status (p=0.041); therefore, the results presented in this article show be accurate to predict the surgical treatment of these lesions / Mestrado / Neurologia / Mestre em Ciências Médicas

M.Ing. (Mechanical Engineering) / A stand-alone anterior lumbar interbody fusion device is used to stabilise the spine and restore the disc space height without any other instrumentation. The stand-alone anterior lumbar interbody device is fixed to the adjacent vertebrae using titanium screws. In this research an experimental and numerical investigation on the structural strength of the SASCATM stand-alone anterior lumbar interbody fusion device are presented. The outcome of the investigation will be used as part of the device validation documentation necessary for market approval. The SASCATM device is manufactured from PEEK (a high strength polymer). Tensile and compressive testing was conducted to determine the appropriate mechanical properties of PEEK. The structural integrity of the SASCA device was evaluated by conducting full scale compression testing on a limited number of different design revisions. Comparisons as regards to their loaddisplacement behaviour were made. All specimens were visually inspected. The Finite Element Analysis (FEA) method was used in the numerical investigation of the SASCATM stand-alone anterior lumbar interbody device. Three studies were conducted. The first study aimed at comparing the full scale experimental compressive testing results with the FEA simulation. Although the desired results weren’t achieved, the model gave a fair representation of the initial region of the experimental setup in the sense that it had a similar slope. It was concluded that the nominal stress (4.1 MPa) fell within the proportional limit (35 MPa) as measured during the materials testing. The second study was aimed at determining the displacement at a worst-case load determined from the literature (2.7 kN). The study showed that the maximum Von Mises stress does not exceed the yield strength of the material. The third and final (parametric) study aimed at geometric optimisation of the cages. The motivation for the changes was based on the literature and customer suggestions for improvement. The geometric optimisation intended to show whether a desired increase in graft hole size would have an effect on the structural integrity of the device. The suggestion to move the screw holes of the threehole version closer to the center of the cage was also assessed. It was shown that enlarging the two graft holes does have an effect on the compressive strength. Higher stresses were presented in all but one case. Combining the holes also had an effect on the compressive strength. Movement of the screw holes more medially did have an impact on the compressive strength of the cages. The effect was significant. The closer the holes were to the center of the cage, the higher the Von Mises stress was. This change should therefore be considered before implementation. The results showed that different shapes and sizes of the graft holes do have an impact on the stress of this particular cage. None of the models exceeded the compressive yield strength of the material. The proposed graft hole opening design changes are therefore not warranted for the current SASCATM stand-alone anterior lumbar interbody device.

This thesis assessed the suitability of unilateral, electrolytic lesions as a model of spinal cord damage and repair in the adult rat. This type of lesion resulted acutely in localized damage in the upper motor neuron at the L2-L3 level of the spinal cord. Minimal acute damage to ascending sensory pathways was indicated by preserved somatosensory evoked potentials elicited by stimulation of the tibial nerve. Immediately after lesion generation one of several substrates was injected into the lesion cavity. These substrates were saline buffer, liquid collagen solution, foetal spinal cord cells from 14 day old rat embryos, and a mixture of collagen and E 14 foetal spinal cord cells. The 4 groups were compared for functional recovery over 3 months using the inclined plane test and a Tarlov movement scale. After sacrifice, the tibialis anterior muscles were dissected and weighed to assess atrophy due to lower motor neuron injury. After removing and embedding the spinal cords in paraffin, transverse and longitudinal sections were taken for cytoarchitectural investigation. Cresyl violet was used to indicate Nissl substance, Luxol fast blue stained for myelin and anti - glial fibrillary acidic protein (GFAP) antibody revealed the expression of GFAP in the cord sections. Chronic electrolytic lesions were characterized by the highly variable degree of cavitation, demyelination and macrophage infiltration that was present. There was no significant performance deficit on the inclined plane test in any of the lesioned groups when compared to unoperated animals. The tibialis muscles from all groups were of normal weight, indicating that the lower motor neurons were not significantly damaged by the lesions used. There was, however, a marked decrease in the number of GFAP reactive astrocytes in the lesioned animals when compared to unlesioned controls (P < 0.01, Wilcoxon test). Moreover, this reduction of GFAP - like immunoreactivity was not prevented by implants of foetal neurons, collagen or foetal neurons suspended in collagen. Possible explanations for the reduced GFAP - like immunoreactivity seen in all electrolytically lesioned cords are discussed. / Medicine, Faculty of / Cellular and Physiological Sciences, Department of / Graduate