Thesis (doctoral)--Lunds Universitet, 1994. / Added t.p. with thesis statement inserted. Includes bibliographical references.

Thesis (M. Phil.)--University of Hong Kong, 2005. / Title proper from title frame. Also available in printed format.

Thesis (Ph. D.)--Oregon State University, 2006. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Thesis (Ph. D.)--Oregon State University, 2006. / Includes bibliographical references.

No description available.

Determining the mechanisms by which growth hormone (GH) enhances bone growth and development has proven difficult. GH can act either systemically via the stimulation of liver insulin like growth factor (IGF)-1, or locally via activation of the GH receptor (GHR). Furthermore, the local actions of GH may be IGF-1 dependent (indirect) or independent (direct). Suppressor of cytokine signalling 2 (SOCS2) has been identified as an important regulator of GH signalling via the JAK/STAT pathway. The SOCS2 knockout (Socs2-/-) mouse is characterised by its overgrowth phenotype despite no elevation in systemic GH and IGF-1 levels. It therefore offers a valid and novel model to investigate the local effects of enhanced GH signalling on the skeleton. The work presented in this thesis investigates the Socs2-/- mouse model to better understand the actions of local GH on longitudinal bone growth and bone accrual. Ex vivo metatarsal organ cultures, osteoblast cultures, and in vivo approaches are used to unravel the mechanisms of GH action on the skeleton. This thesis also explores the potential of SOCS2 as primary mediator of inflammatory induced bone loss through the utilisation of the dextran sulphate sodium (DSS) model of colitis. Embryonic and postnatal ex vivo metatarsal organ cultures are used to study the mechanism of GH action on longitudinal bone growth. Specifically, the present work highlights that enhanced linear growth in the absence of SOCS2 is associated with an increase in the GH regulated proteins, IGF-2 and IGF binding protein 3 (IGFBP3), but not IGF-1. This indicates that IGF-1 may not be essential for mediating GH action on bone growth. Completion of an in depth analysis of the bone phenotype of juvenile and adult, male and female Socs2-/- mice reveals an anabolic phenotype consistent with increased GH signalling. Male Socs2-/- mice are shown to have a greater enhancement of cortical parameters compared to females, resulting in increased bone strength. Investigation of the mechanisms behind the enhanced bone accrual in Socs2-/- mice identifies SOCS2 as the primary SOCS protein regulating GH signalling in primary osteoblasts. The JAK/STAT pathway is confirmed as the key signalling pathway targeted by SOCS2. Despite this enhanced signalling there is little evidence presented in this thesis to suggest that GH actions on osteoblasts and ultimately bone mass are mediated through increased Igf1 expression. GH treatment is shown to be anabolic to bone of young juvenile Socs2-/- mice, but not WT mice. This increase in bone mass is associated with increase bone p-STAT5 signalling, but no increase in Igf1 levels indicating that GH may have IGF-1 independent effects in the Socs2-/- mouse model. GH treatment of young mice also reveals an age and sex specific effect of GH action where GH does not stimulate growth until approximately 3 weeks of age. From 3 weeks of age, WT female mice show increased growth in response to GH, but males do not. The increased growth is associated with increased p-STAT5 signalling and increased bone area. This thesis also confirms SOCS2 a critical mediator of bone loss associated with inflammation. The present results show that deteriorated trabecular bone health in colitic mice is associated with elevated Socs2 expression in bone. Furthermore, despite similar levels of gut inflammation observed in Socs2-/- mice with DSS induced colitis these mice are partly protected from poor bone health. The work described herein has used the Socs2-/- mouse model to strengthen our understanding of the actions of local GH on skeletal growth and development. It also provides compelling evidence for the importance of SOCS2 as a mediator of bone loss in cases of inflammatory bowel disease.

The Hedgehog (Hh) signalling pathway is essential for embryogenesis and regulating cellular homeostasis in the adult, however much remains unknown about the molecular mechanisms that control ligand expression. In 2002, Lee et al. demonstrated that conditional mutation of the Drosophila hyperplastic discs gene (hyd) resulted in increased hh levels, suggesting that Hyd can act as a negative regulator of hh gene expression. Based on this evidence, the aim of this project was to investigate the hypothesis that UBR5, the murine homologue of Hyd, acts as a novel regulator of Hh gene expression in mammals. To investigate this hypothesis in vivo, I utilized the developing mouse limb as a model system that is highly sensitive to abnormal Hh expression. Morphological analysis of Ubr5 limb mutant embryos did not reveal an obvious phenotype, however quantitative analysis of Ihh gene expression and its downstream targets at E13.5 demonstrated a significant decrease in levels. In addition, changes in the expression of Runx2 and Msx2 were detected. Therefore, these data indicate that UBR5 can act as a positive regulator of Ihh expression, in addition to regulating other factors involved in chondrogenesis. The role for UBR5 as a positive regulator of Hh expression was also supported by in vitro investigations, demonstrating that UBR5 is required for Shh expression in mouse embryonic stem cells. Morphological analysis of adult Ubr5 limb mutant mice revealed the presence of significantly shorter long bones. These observations support previous reports that interference with IHH during early chondrogenesis can negatively affect long bone growth in the adult. Interestingly, adult Ubr5 limb mutant mice also possess osteophytes, a feature typically observed in osteoarthritis (OA), in addition to sites of ectopic mineralization (EM) near tendons of the knee and ankle. Based on these observations and evidence from the literature, I hypothesize that in addition to the role for UBR5 as a positive regulator of Ihh expression in the bone, UBR5 also plays a role in ligament/tendon development and/or maintenance, whereby its loss results in defective ligaments/tendons that are incapable of stabilizing the joints of the limb, culminating in joint deterioration, as observed in OA, in addition to EM. However, further investigation is required to determine whether this is also related to deregulated Ihh. These experiments suggest that Ubr5 limb mutant mice could provide a novel mouse model in the study of OA and prompt the investigation of the potential role for EDD, the human homologue of UBR5, in OA initiation and progression.

5-Aminolevulinic acid (ALA), one of the body's naturally occurring molecules in the biosynthetic pathway to haem, is being used in Photodynamic Therapy (PDT), a new approach to the treatment of cancer. It is a highly reactive molecule, which, upon standing in solution, dimerises to give 2,5-di-(beta-carboxyethyl) pyrazine. This reaction, and other similar ones, have been studied in some detail as it remains a major problem in the clinic, lowering the dose of active drug being administered and forming a molecule of which the toxicology is not known. The initial product of dimerisation is a dihydropyrazine, which is immediately oxidised in air to give a pyrazine. The chemistry of dihydropyrazines has also been investigated. The chemical synthesis of ALA itself has been optimised and derivatives of the molecule have been prepared to try to prevent this dimerisation from occurring and, potentially, increase the tissue selectivity of the drug. Twelve derivatives of ALA have been prepared and biologically tested for their activity in PDT.

Orientador: Julio Cezar de Melo Castilho / Banca: Edmundo Medici Filho / Banca: Kurt Faltin Junior / Banca: Cristina Lúcia Feijó Ortolani / Banca: Mônica Fernandes Gomes / Resumo: O presente trabalho visa identificar e evidenciar a curva de crescimento em animais utilizados em pesquisa laboratorial. Em muitos casos a idade biológica se torna fundamental para resultados precisos e confiáveis, em especial na ortodontia, pois a maturação óssea é avaliada por meio de radiografias, e as mudanças observadas indicam em qual estágio se encontra o indivíduo. A idade cronológica sem dúvida é a mais utilizada, sendo observada mesmo antes do nascimento, durante a gestação e até os últimos dias de vida deste indivíduo. Contudo a idade cronológica em alguns casos não evidencia a exatidão da fase de maturação; um dos métodos utilizados é a avaliação da maturação das vértebras cervicais. A método que foi utilizada na avaliação das alterações das vértebras em animais foi a mesma que os autores utilizam em humanos. Sendo assim, esse trabalho tem como objetivo principal a identificação da idade óssea em animais para limitar a distribuição dos mesmos, contribuindo com a eficiência nos experimentos quando a idade e fase do desenvolvimento pode influenciar nos resultados das pesquisas. Os 35 ratos Wistar foram observados por um período de 160 dias, iniciando pelo 22º dia (desmame), com cortes transversais periódicos para pesagem, medição do comprimento e radiografias digitais obtidas com os animais imobilizados por anestésicos. As imagens radiográficas das vértebras cervicais (C2 e C3) foram sumetidas a densitometria ótica e mensuradas por meio de um programa de computador. As variáveis foram submetidas à análise estatística individual e relacionadas entre si obtendo resultados significantes para o crescimento (p<0,001). O grupo masculino apresenta médias significantes maiores que as do grupo feminino em todas as avaliações realizadas (p<0,001). Para a densidade houve aumento conforme... (REsumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim of this study was to identify and evidence the growth curve of animals used for laboratorial research purposes. The biological age is important for precise and reliable results, especially in orthodontics, since radiographs are used to evaluate the bone maturation and the stage in which is the patient according to the changes that are observed. The chronological age is certainly the most utilized, been observed even before birth, during pregnancy until the person's last days of life. However, the chronological age, in some cases, does not evidence exactly the maturation phase. Thus, the evaluation of bone age or maturation of cervical vertebras is a commonly used method.The methodology used for the evaluation of the vertebral alterations in animals was the same that used in humans. Therefore, the main objective of this study was the identification of the bone age in animals to limit indiscriminate use, contributing with the experiences efficiency when the age and development phase can influence the research results. The 35 Wistar rats were observed for a period of 260 days, beginning in the 22nd day (weaning). Periodical transversal cuts for weight analysis, length measurement and digital radiographs were taken with the animals immobilized by anesthetics. The radiographic images of cervical vertebras (C2 and C3) were submitted to optical densitometry and measured by computer software. The variables were submitted to individual and each other related statistical analysis. The results were significant for growth (p< 0.001). The male group showed significantly higher mediums, than that showed by the female group in all evaluations. Conclusion: There exist a growth outbreak and the growth curves of weight and length, and the alterations... (Complete abstract click electronic access below) / Doutor

Orientador: Horácio Faig Leite. / Banca: João Batista César Neto / Banca: Raquel Guedes Fernandes Pires / Banca: Maria Aparecida Neves Jardini / Banca: Warley David Kerbauy / Resumo: O objetivo desse estudo foi avaliar o efeito do uso local de uma solução aquosa de risendronato de sódio (RS) em diferentes concentrações na inibição da perda óssea alveolar decorrente de periodontite experimental induzida em ratas. Os 48 animais foram divididos em 2 grupos constituídos por 24 animais: GD (dupla aplicação) e GU (única aplicação). Os dois grupos foram subdivididos em 8 subgrupos: R1 (duas aplicações de 0,125 mg de RS), R2 (duas aplicações de 0,25 mg de RS), R3 (duas aplicações de 0,5 mg de RS) e A1 (duas aplicações de água destilada); R4 (uma aplicação de 0,125 mg de RS), R5 (uma aplicação de 0,25 mg de RS), R6 (uma aplicação de 0,5 mg de RS) e A2 (uma aplicação de água destilada). Foi induzida a periodontite pela confecção de ligaduras ao redor dos primeiros molares inferiores direitos em todos os animais. Nos grupos A1 e A2, os molares contralaterais serviram de controles negativos (C1 e C2). A medicação foi aplicada aos 5 e 10 dias após indução da periodontite nos animais do GD, e nos animais do GU apenas aos 10 dias. Decorrente 15 dias os animais foram submetidos à eutanásia. Foram feitas análises histológica, histomorfométrica, imuno-histoquímica anti-osteocalcina e enzimo-histoquímica para TRAP (fosfatase ácida tartarato resistente). Os grupos que receberam RS exibiram maior volume trabecular da crista óssea remanescente que o controle significante estatísticamente, mas não foram observados diferenças entre os grupos tratados. A perda óssea alveolar foi menor nos grupos tratados com risendronato comparado com controle e foi dose-dependente. Os grupos que receberam a menor dose (R1 e R4) apresentaram menor perda óssea estatisticamente... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim of this study was to evaluate the local use of an aqueous solution of sodium risendronate (RS) at different concentrations on the inhibition of alveolar bone loss caused by experimental periodontitis induced in rats. The 48 animals were divided into two groups consisting of 24 animals: GD (double application) and GU (one application). The two groups were subdivided into eight subgroups: A1 (two applications of 0.125 mg RS), R2 (two applications of 0.25 mg RS), R3 (two applications of 0.5 mg RS) and A1 (two applications of distilled water), and R4 (one application of 0.125 mg RS), R5 (one application of 0.25 mg RS), R6 (one application of 0.5 mg RS) and A2 (one applications with distilled water). Periodontitis was induced in first molars in all animals. In groups A1 and A2, the contralateral molars served as controls (C1 and C2). The medication was applied at 5 and 10 days after induction of periodontitis in animals of GD, and animals of GU only after 10 days. After 15 days the animals were euthanized. Analysis was performed on histological, histomorphometric, immunohistochemical antiosteocalcin and enzimohistochemical for TRAP (tartrate resistant acid phosphatase). The groups that received RS exhibited greater volume of trabecular bone crest that controlling statistically significant, but no differences were observed between treated groups. The alveolar bone loss was lower in treated groups compared with placebo and was dose-dependent. The groups that received the lowest dose (R1 and R4) showed statistically significant less bone loss than the intermediate dose (R2 and R5), which in turn exhibited lower rates compared with higher doses (R3 and R6). The two types of approaches, however, did not show statistical significance. The number of TRAP-positive cells was... (Complete abstract click electronic access below) / Doutor