Osteoarthritis (OA) is a prevalent joint disease without a cure and leading cause of disability worldwide. Knee OA is the most common and expected to increase with a growing, aging population. OA is clinically diagnosed by the measure of joint space narrowing on a radiograph and pain scores, though OA is now known to be a disease of the whole joint and characterized by cartilage degradation, subchondral bone sclerosis, synovitis, meniscal erosion and inflammation. There are currently no disease-modifying therapies because the pathogenesis and progression of these events are unknown. Recent studies have demonstrated the importance of subchondral bone in OA initiation. Using an advanced imaging technique called individual trabecula segmentation (ITS) to decompose the trabecular network into individual plates and rods, subtle microstructural changes were identified beneath both intact and damaged cartilage in human OA. These findings were also observed during OA initiation before cartilage changes in a model of guinea pig OA. The aims of this study were to further investigate these bone microstructural changes and investigate how they affect the mechanical properties of trabecular bone and overlying articular cartilage. In the first aim, the Dunkin-Hartley guinea pig model of spontaneous OA was used to quantify ITS-based trabecular microstructural changes in the knee joint during OA initiation in both a longitudinal and cross-sectional analysis. In the longitudinal study, microstructural changes in the subchondral bone were quantified from μCT images and voxel-based modeling and remodeling. In the cross-sectional study, structural, biomechanical and biochemical properties of articular cartilage, subchondral bone plate and trabecular bone were analyzed. In both the longitudinal and cross-sectional analyses, there was a trend towards increased thickness, a significant decrease in porosity, and increased mineralization in the subchondral bone plate. There was an increase in the plate-to-rod (PR) ratio due to a loss of trabecular rods, an increase of trabecular plates, and thickening of trabecular plates before any visible histological changes in the cartilage. Voxel-based bone modeling and remodeling analysis confirmed that there was a loss of rods and not merely that the rods were turning into plates. This confirmed our hypothesis that trabecular rod loss precedes cartilage damage and could be a potential therapeutic target. There was a trend towards an increase in the apparent elastic modulus of bone followed by a reduction in the modulus, with the stiffest and most drastic reduction in the medial tibial plateau, which coincided with cartilage fibrillations and a trend towards reduction in the cartilage aggregate modulus. The tissue-level mechanical properties of the trabecular bone are due to both microstructural changes in the trabecular network and material changes in the tissue modulus. Micro-indentation of the trabecular bone revealed a trend towards an increase in the tissue modulus in the medial tibial plateau, followed by a reduction in the tissue modulus. This suggested that during OA progression, there is rapid formation of lower-quality bone with a reduced capacity to mechanically support the joint. In summary, there were structural and mechanical bone changes observed before histological, mechanical or biochemical changes in the articular cartilage. In the second aim, a mechanically-driven subchondral bone computational model was developed. Under equilibrium conditions to simulate aging, there was no change in bone volume fraction and there was a shift from plate-like to rod-like trabecula. There was a slight decrease in the apparent elastic modulus of the bone. Under increased applied strain to simulate the effects of obesity, there was an increase in bone volume fraction, due to both a rod loss and plate thickening. This change came from rod loss, rods thickening and becoming plates, as well as rods and plates merging together. These microstructural changes caused an increase in the apparent elastic modulus of bone. This study demonstrated that the microstructural changes observed in OA can be simulated by increasing the applied strain. Taken together, these studies demonstrate how bone microstructural changes in OA initiation affect the mechanical integrity of the subchondral bone and could cause abnormal stress distributions in the overlying cartilage and promote cartilage degradation. Therapies that prevent bone loss, like bisphosphonates, could be investigated to prevent this initial rod loss as a means of potentially slowing or reversing OA progression.

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As complement is now believed to have some function in immunity it becomes of interest to determine what effect, if any, cortisone may have upon complement concentration in animal sera.

published_or_final_version / Biochemistry / Doctoral / Doctor of Philosophy

Maternal cardiovascular adaptations appear to be essential in order to supply extra circulation to both the developing fetus and maternal system during a successful pregnancy. Since inadequate cardiovascular adjustments may produce abortions or maternal morbidity, the characterization of maternal cardiovascular changes during pregnancy and the elaboration of the underlying mechanism for these changes are essential to the understanding of how the heart enlarges during pregnancy and what significance this enlargement might have. To provide needed information regarding this time course and extent of maternal cardiac enlargement and the hormonal and hemodynamic changes which may be responsible for these changes, the guinea pig was used as an animal model to characterize the maternal cardiac, hemodynamic and hormonal changes during early, mid and late pregnancy.

INTRODUÇÃO: Vários estudos têm mostrado a importância da Rho quinase na modulação da contração do músculo liso, hiperresponsividade das vias aéreas e inflamação. Entretanto, os efeitos do tratamento crônico com um inibidor específico desta via não haviam sido previamente investigados. MÉTODOS: No presente estudo, foram avaliados os efeitos do tratamento crônico com Y-27632, um inibidor altamente seletivo Rho quinase, sobre a hiperresponsividade das vias aéreas, a ativação do estresse oxidativo, o remodelamento da matriz extracelular, a inflamação eosinofílica e a expressão de citocinas em um modelo animal de inflamação crônica das vias aéreas. As cobaias foram submetidas a sete inalações com ovalbumina ou solução salina (duas vezes por semana durante quatro semanas). Inalações com o inibidor da Rho quinase (Y-27632; 1mM) foram realizadas 10 min antes de cada exposição ao antígeno, começando na quinta inalação. Setenta e duas horas após a 7ª inalação, a avaliação da mecânica pulmonar foi realizada e o óxido nítrico exalado foi coletado. Os pulmões foram então removidos e a análise histológica foi realizada utilizando morfometria. RESULTADOS: O tratamento com Y-27632 em animais sensibilizados reduziu o óxido nítrico exalado, as respostas máximas de resistência e elastância do sistema respiratório, o número de eosinófilos, o conteúdo colágeno e fibras elásticas, o número de células positivas para IL-2, IL-4, IL-5, IL-13, iNOS, MMP -9, TIMP-1, TGF-, NFkappa B e IFN-, e o conteúdo de 8-iso-PGF2 em relação ao grupo não tratado (p<0,05). Houve correlação positiva entre as respostas funcionais e os marcadores de inflamação, remodelamento e ativação da via de estresse oxidativo avaliados. CONCLUSÕES: A ativação da vida da Rho quinase contribui para a potencialização da hiperresponsividade, inflamação, processo de remodelamento da matriz extracelular e ativação do estresse oxidativo. Estes resultados sugerem que os inibidores da Rho quinase podem ser uma ferramenta farmacológica em potencial para o controle da asma / INTRODUCTION: Several studies have shown the importance of Rho-kinase in the modulation of smooth muscle contraction, airway hyperresponsiveness and inflammation. However, the effects of chronic treatment with a specific inhibitor of this pathway had not been previously investigated. METHODS: We evaluated the effects of chronic treatment with Y-27632, a highly selective Rho-kinase inhibitor, on airway hyperresponsiveness, oxidative stress activation, extracellular matrix remodeling, eosinophilic inflammation and cytokines expression in an animal model of chronic airway inflammation. Guinea pigs were submitted to seven ovalbumin or saline exposures (twice a week for four weeks). Rho-kinase inhibitor (Y-27632; 1mM) was aerosolized 10 min before each antigen exposure, beginning at the 5th inhalation. Seventy-two hours after the 7th inhalation, pulmonary mechanics evaluation was performed and exhaled nitric oxide was collected. Lungs were removed and histological analysis was performed using morphometry. RESULTS: Treatment with Y-27632 in sensitized animals reduced exhaled nitric oxide, maximal responses of resistance and elastance of respiratory system, eosinophils, collagen and elastic fibers content, IL-2, IL-4, IL-5, IL-13, iNOS, MMP-9, TIMP-1, TGF-, NFkappa B and IFN- positive cells, and 8-iso-PGF2 content compared to the non-treated group (P<0.05). There were positive correlations among the functional responses and the markers of inflammation, remodeling and oxidative stress pathway activation evaluated. CONCLUSIONS: Rho-kinase pathway activation contributes to the potentiation of the hyperresponsiveness, inflammation, extracellular matrix remodeling process and oxidative stress activation. These results suggest that Rho-kinase inhibitors may be a potential pharmacological tool for controlling asthma

INTRODUÇÃO: A relevância do parênquima pulmonar distal na fisiopatologia da asma tem sido intensamente enfatizada. Vários estudos sugerem a inibição da Rho quinase como uma intervenção benéfica e promissora na asma. Entretanto, não há estudos anteriores que avaliaram os efeitos destes inibidores na modulação da mecânica do parênquima pulmonar e suas alterações histopatológicas em um modelo animal de inflamação pulmonar alérgica crônica. OBJETIVO: Avaliar a inibição da Rho quinase (Y-27632) na modulação da responsividade, inflamação, remodelamento da matriz extracelular e ativação do estresse oxidativo no parênquima pulmonar de cobaias com inflamação pulmonar alérgica crônica. MÉTODOS: As cobaias receberam sete inalações de ovalbumina (1-5 mg / ml; grupo OVA) ou salina (grupo SAL) ao longo de quatro semanas. A partir da quinta inalação, os animais do grupo Rho quinase foram submetidos a inalação com Y-27632, 10 minutos antes de cada inalação com OVA ou SAL. Setenta e duas horas após a sétima inalação, os animais foram anestesiados e exanguinados, e das tiras do tecido pulmonar foram realizadas a mecânica oscilatória, sob condições basais e após o desafio de ovalbumina (0,1%). Após a mecânica, as fatias de pulmão foram submetidas a análise histológica por meio da morfometria. RESULTADOS: A inibição de Rho quinase nos animais expostos à ovalbumina atenuou a elastância e a resistência tecidual, o número de eosinófilos, a expressão de IL-2, IL-4, IL-5, IL-13, TIMP-1, MMP-9, TGF-, IFN-g, NF-kB e iNOS e o conteúdo de 8-iso-PGF2, fibras elásticas, fibras colágenas e actina em comparação com o grupo OVA (P<0,05). CONCLUSÃO: A inibição da Rho quinase contribui para o controle da capacidade de responsividade do parênquima pulmonar, da inflamação eosinofílica, das respostas Th1/Th2, ao controle do remodelamento da matriz extracelular em um modelo animal de inflamação pulmonar alérgica crônica. Podendo ser considerada uma futura ferramenta farmacológica para o tratamento de doenças pulmonares crónicas. / RATIONALE: Previous studies with Rho-kinase inhibitors suggest a beneficial influence of these drugs in asthma. The relevance of distal lung tissue in functional asthmatic impairment has been intensely emphasized. There have not been any previous studies evaluating the effects of these inhibitors on the modulation of distal lung mechanics and histopathological alterations in an animal model of chronic pulmonary inflammation. OBJECTIVE: To evaluate if Rho-kinase inhibition (Y- 27632) modulates distal lung responsiveness, inflammation, extracellular matrix remodeling and oxidative stress activation in guinea pigs with chronic allergic inflammation. METHODS: Guinea pigs received seven inhalations of ovalbumin (1-5 mg/ml; OVA group) or saline (SAL group) over 4 wk. From the 5th inhalation, the Rho-kinase group animals were submitted to Y-27632 inhalation 10 min before each inhalation with OVA or SAL. Seventy-two hours after the seventh inhalation, the animals were anesthetized and exsanguinated, and oscillatory mechanics of the lung tissue strips were performed under the baseline condition and after the ovalbumin challenge (0.1%). Afterwards, the lung slices were submitted to morphometry. RESULTS: The Rho-kinase inhibition in the ovalbumin-exposed animals attenuated the tissue elastance and resistance, eosinophils, the IL-2, IL-4, IL-5, IL-13, TIMP-1, MMP-9, TGF-, IFN-g, NF-kB, iNOS-positive cells and the 8-iso-PGF2, elastic, collagen and actin content compared with the OVA group (P<0.05). CONCLUSION: Rho-kinase inhibition contributes to the control of distal lung responsiveness and the eosinophilic and Th1/Th2 responses to the control of extracellular matrix remodeling in an animal model of chronic allergic inflammation. It may be considered a future pharmacological tool for the treatment of chronic pulmonary diseases.

A dor é um fenômeno multidimensional, que geralmente desencadeia reações emocionais desconfortáveis quando identificada. Sua relação com injúria tecidual pode ser interpretado como um mecanismo adaptativo de defesa à integridade do organismo, tendo em vista sua preservação evolutiva. Porém, o substrato neurobiológico do organismo parece determinar a complexificação do repertório comportamental em diferentes espécies. Nesse sentido, o córtex cingulado anterior (CCA) tem sido amplamente descrito em mamíferos modulando diferentes aspectos da dor. O presente trabalho utilizou os testes algesimétricos de vocalização e da formalina em cobaias, para se avaliar o decurso temporal do efeito da microinjeção de agonistas e antagonistas GABAérgico (muscimol e bicuculina); colinérgico (carbacol e atropina) e opioidérgico (morfina e naloxona). A microinjeção de bicuculina (1 nmol / 0,2 µl) exacerbou as respostas nociceptivas em ambos os testes, porém diferentes doses de muscimol (0,5, 1 e 2 nmol / 0,2 µl), não modificaram as respostas. O efeito da bicuculina foi bloqueado em ambos os testes pela microinjeção prévia de muscimol (1 nmol/ 0,2 µl) no CCA. A microinjeção de carbacol (2,7 nmol /0,2 µl) neste substrato promoveu antinocicepção, evidenciada por meio da atenuação da amplitude das vocalizações, mas não pelo teste da formalina. Esse efeito foi bloqueado pela administração prévia de atropina (0,7 nmol /0,2 µl) e de naloxona (2,7 nmol /0,2 µl). A microinjeção de morfina (4,4 nmol /0,2 µl) promoveu antinocicepção em ambos os testes. Concluímos que a inibição do tônus GABAérgico no CCA exacerba os comportamentos nociceptivos e que a antinocicepção promovida por carbacol pode ter sido mediada pelo sistema de opióides endógenos, tendo em 9 vista o bloqueio do seu efeito com naloxona. Além disso, a estimulação opióide promove uma contundente antinocicepção. / Pain is a multidimensional phenomenon which usually triggers uncomfortable emotional reactions when identified. Its relation injury can be interpreted as an adaptive mechanism to defend the integrity of the body given its evolutionary conservation. However the neurobiological substrate of the body seems to determine the complexification of behavioral repertoire in different species. Thus, the anterior cingulated cortex (ACC) has been widely described in mammals by modulating different cognitive aspects of pain. This study used algesimetric tests of vocalization and formalin in guinea pigs to evaluate the time course of the effect of microinjection of GABA agonists and antagonists (bicuculline and muscimol) and cholinergic (carbachol and atropine) beyond the opioid antagonist naloxone. The microinjection of bicuculline (1 nmol / 0,2 µl) exacerbated the nociceptive behavior in both tests but different doses of muscimol (0,5; 1 e 2 nmol / 0,2 µl) did not change the responses. The effect of bicuculline was blocked in both tests by prior microinjection of muscimol (1 nmol / 0,2 µl) in the ACC. The microinjection of carbachol (2,7 nmol / 0,2 µl) on this substrate promoted antinociception as evidenced by attenuation of the amplitude of the vocalizations, but not by the formalin test. This effect was blocked by prior administration of atropine (0,7 / 0,2 µl) and naloxone (0,7 nmol / 0, 2 µl). The microinjection of morphine (4,4 nmol / 0,2 µl) promoted antinociception in both tests. We conclude that inhibition of GABAergic tone in the ACC exacerbates nociceptive behaviors and that the antinociception promoted by carbachol may 11 have been mediated by endogenous opioid system in order blocking its effect with naloxone. In addition opioid stimulation promotes a striking antinociception.