Orientador: Carlos Alberto Hussni / Resumo: As enfermidades podais do membro torácico são a maior causa das alterações musculoesqueléticas que acometem os equinos. A doença do navicular, osteíte podal e a laminite estão entre as enfermidades de maior incidência em equinos, sendo todas elas citadas como afecções de origem vascular. A fotopletismografia é um método diagnóstico não invasivo que quantifica o tempo de reenchimento venoso baseado na circulação periférica terminal. Objetivou-se estudar a exequibilidade e viabilidade da fotopletismografia podal em equinos, padronizando os valores normais para a espécie. Foram utilizados 10 equinos hígidos, avaliando-se os membros torácicos em diferentes superfícies, sendo dividos em dois grupos: Grupo Borracha (GB) e Grupo Concreto (GC). A fotopletismografia foi realizada com os animais em posição quadrupedal, realizando-se movimentos pendulares para mimetizar movimentos de apoio e elevação do membro, realizando-se cinco movimentos consecutivos e então, imediatamente induzidos ao repouso, obtendo-se então, o tempo de reenchimento venoso (TRV). Não houve diferença significativa entre o membro torácico direito e membro torácico esquerdo nos diferentes grupos (p=0,75). A média do TRV nos equinos do grupo borracha (GB) foi de 12,650 ± 1,694 e no grupo concreto (GC) foi de 12,700 ± 1,387 segundos, não demonstrando diferença significativa entre os diferentes pisos (p=0,98). Os equinos apresentaram valores de referência significativos em relação aos pacientes humanos. Conclui-se que ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The thoracic limb disorders are the major cause of the musculoskeletal changes affecting the horses. Navicular disease, foot osteitis and laminitis are among the diseases of higher incidence in equines, all of which are cited as affections of vascular origin. Photoplethysmography is a noninvasive diagnostic method that quantifies venous refill time based on the terminal peripheral circulation. The objective is study the feasibility of foot photoplethysmography in horses, standardizing the normal values for this species. Thoracic limbs were used on different surfaces and divided into two groups: Rubber Group (RG) and Concrete Group (CG). The photoplethysmography was performed with the animals in a quadrupedal position, with pendular movements being performed to mimic support and elevation movements. Five consecutive movements were performed, and then immediately induced at rest, and venous refilling time (VRT). There was no significant difference between the right and left thoracic limbs in the different groups (p=0.75). The mean TRV in the horses of the rubber group (GB) was 12.650 ± 1.694 and the concrete group (CG) it was 12.700 ± 1.387 seconds, showing no significant difference between the different floors (p=0.98). The reference values in horses are different in relation to human patients. It can be concluded that the photoplethysmography of the thoracic limbs in horses can be used as an auxiliary method to evaluate the microcirculation of the foot, the reference value fo... (Complete abstract click electronic access below) / Doutor

Une brosse de polymères est une matrice dense de macromolécules greffées à une surface donnée. Au-delà des brosses synthétiques réalisées en laboratoire, on trouve des exemples très variés dans la nature: un exemple emblématique est le glycocalyx endothélial, décorant la surface interne des vaisseaux sanguins des mammifères. L'interaction de cette structure avec le plasma et les cellules sous écoulement n'est encore que très partiellement explorée. La présente thèse propose, grâce à des simulations de "Dissipative Particle Dynamics", un modèle coarse-grained pour une analyse auto-cohérente d'une brosse polymérique dense sous écoulement parabolique. Cette étude mésoscopique met en évidence l'importance des effets collectifs entre molécules, entraînée par l'hydrodynamique, et propose des nouvelles interprétations à la phénoménologie du système brosse-écoulement. Des résultats préliminaires sont également produits pour l'interaction sous écoulement entre un objet mésoscopique déformable (prototype d'un globule rouge) et les polymères greffés. / Polymer brushes are dense matrices of grafted macromolecules. In addition to brushes finely designed in laboratory, various examples are offered by Nature, as the endothelial glycocalyx, decorating the lumen of mammalian blood vessels. The interaction of such network with the flowing plasma and cells is still partially unknown.The present thesis, by mean of Dissipative Particle Dynamics simulations, proposes a coarse-grained model for the self-consistent analysis of a dense polymer brush under parabolic flow. Our mesoscale investigation highlights the relevance of collective effects, driven by hydrodynamics, and proposes novel interpretations regarding the rich phenomenology of the brush-flow system.Preliminary results are also provided for the interplay between a mesoscopic deformable flowing object (prototype of a red blood cell) and the grafted polymers.