<p>Asthma is a disease characterized by transient airway smooth muscle contraction leading to episodes of reversible airway narrowing. It affects over 300 million people worldwide and is implicated in over 250 000 deaths annually. The primary clinical features of asthma include airway inflammation, hyperresponsiveness, and remodeling. Generally, asthmatic patients experience exacerbations between periods of diminished symptoms. Interestingly, in addition to these above mentioned hallmarks, asthmatics have also been shown to react differently to ventilatory mechanical strain. This is most evident when assessing the effect of a deep inspiration (DI), clinically measured as a breath taken from functional residual capacity to total lung capacity, in healthy individuals <em>versus</em> asthmatics. These deep inspiratory efforts have been shown to produce a bronchodilatory response in healthy individuals, whereas in asthmatics, DIs are less effective in producing bronchodilation, can cause more rapid airway re-narrowing, and even bronchoconstriction in moderate to severe asthmatics. The mechanism by which a DI is able to cause bronchoconstriction remains ambiguous. Previous theories suggest that this phenomenon is intrinsic to airway smooth muscle (ASM) itself. However, the airway inflammation present in asthmatic airways may also add to the increased ASM contractility following stretch, by the release of mediators that can prime the contractile apparatus to react excessively in the presence of stretch.</p> <p>Thus, collectively, the studies contained in this thesis are linked to the general theme of greater characterization of the signalling mechanisms that regulate airway stretch-activated contractions using a pharmacological approach in intact bovine bronchial segments, with the hope of providing novel insights into the mechanisms that regulate the DI-induced bronchoconstriction seen in asthmatics.</p> / Doctor of Philosophy (Medical Science)

Malignant cutaneous melanoma is the deadliest form of skin cancer, and a majority of melanoma diagnoses are a result of exposure to ultraviolet (UV) radiation. UV radiation causes DNA damage, which if not repaired correctly via nucleotide excision repair (NER) can result in mutations and melanomagenesis. The melanocortin 1 receptor (MC1R) is a Gs protein coupled receptor located on melanocyte plasma membranes and is involved in protecting the skin from UV induced damage. MC1R signaling results in the activation of two protective pathways: 1) induction of eumelanin synthesis downstream of micropthalmia-associated transcription factor (MITF) and 2) acceleration of NER downstream of ataxia telangiectaseia mutated and Rad3 related (ATR). MC1R signaling, however, also promotes melanocyte proliferation, therefore, the activation of the MC1R pathway must be regulated. The overall hypothesis of this dissertation is that the pathways downstream of MC1R can be manipulated to protect against UV induced damage. Chapter 2 investigates the regulation of the MC1R neutral antagonist human β-defensin 3 (βD3). UV damage did not induce βD3 mRNA expression in ex vivo human skin explants. The induction of βD3 expression instead correlated with inflammatory cytokines including TNF. Chapter 3 investigates the interdependence and cross talk between the two protective pathways downstream of MC1R. We directly tested the effect of MITF on the acceleration of NER and the effect of ATR on the induction of eumelanin synthesis following MC1R activation. MITF was not required for the acceleration of NER as mediated by ATR, however, the induction of transcription of enzymes involved in eumelanin synthesis was dependent upon ATR kinase activity. Finally, Chapter 4 investigates the mechanism by which MC1R promoted proliferation and whether the two UV protective pathways downstream of MC1R could be selectively activated without the risk of melanocyte proliferation. MC1R signaling resulted in activation of the mechanistic target of rapamycin complex 1 (mTORC1), a major regulator of cell growth and proliferation. Inhibition of mTORC1 signaling via rapamycin prevented MC1R induced proliferation in vitro. Rapamycin, however, did not prevent MC1R induced eumelanin synthesis or the acceleration of NER in vitro or in vivo suggesting it is possible to selectively activate the beneficial signaling pathways without the risk of melanocyte proliferation. The results of this dissertation suggest that MC1R signaling could be augmented in individuals to prevent UV induced damage.

<p> G93A SODI mice (G93A mice) are a transgenic model over-expressing a mutant human Cu/Zn-SOD gene, and are a model for amyotrophic lateral sclerosis (ALS), a predominantly motor neurodegenerative disease. Hippocampal neurogenesis in the subgranular zone (SGZ) of dentate gyms (DG) occurs throughout the life. It is regulated by many pathological and physiological processes. There is controversy with respect to the basal level of hippocampal neurogenesis and its response to exercise in neurodegenerative diseases and their mouse models. Little information regarding hippocampal neurogenesis is available in G93A mice. The present study was designed to study the impact of treadmill exercise and sex differences on hippocampal neurogenesis in this model. In addition, potential molecular mechanisms regulating hippocampal neurogenesis including growth factors (BDNF and IGFl) and oxidative stress (SOD2, catalase, 8-0Hdg, and 3-NT) were also addressed in the study. Bromodeoxyuridine (BrdU) was used to label newly generated cells. G93A and wild type (WT) mice were subjected to treadmill exercise (EX) or a sedentary (SEO) lifestyle. Immunohistochemistry was used to detect BrdU labeled newly proliferating cells, surviving cells, and their phenotype, as well as for determination of oxidative stress. BDNF and IGFl mRNA expression was assessed by in situ hybridization. Results showed that (1) G93A mice had an elevated basal level of hippocampal neurogenesis for both cell survival and neuronal differentiation, a growth factor (BDNF mRNA), and an oxidative stress marker (NT), as compared to wild type sedentary mice. (2) Treadmill running did not show any further effect on hippocampal neurogenesis, growth factors, oxidative stress, and antioxidant enzymes in G93A mice, while treadmill running promoted hippocampal neurogenes1s and expression of the growth factor (BDNF mRNA), and lowered oxidative stress (8-0Hdg) in WT mice. (3) There also were sex differences in hippocampal neurogenesis in G93A mice, whereby male G93A mice had a significant higher level of cell proliferation but a lower level of survival than female G93A mice. (4) The DG BDNF mRNA was associated with cell survival and neuronal differentiation in sedentary G93A mice, suggesting that BDNF is associated with a higher basal level of hippocampal neurogenesis in G93A mice. We conclude that G93A mice are more permissive in the context of hippocampal neurogenesis, which is associated with elevated DG BDNF mRNA expression. Running did not have impact on hippocampal neurogenesis and BDNF mRNA expression in G93A mice, probably due to a 'ceiling effect' of the already heightened basal levels of hippocampal neurogenesis and BDNF mRNA in this model. In addition, sex differences also affect hippocampal neurogenes1s, but the further study is needed to clarify the underlying molecular mechanisms. </p> / Thesis / Doctor of Philosophy (PhD)

<p>Obstructive lung diseases limit airflow and gas exchange and have a major impact on a patient’s long-term health. Asthma and chronic obstructive pulmonary disease (COPD) are the most prevalent obstructive lung diseases and represent a major burden on healthcare systems worldwide. It is now accepted that the pathologies associated with these diseases are heterogeneous in nature, and as the function of the lung is determined by its three-dimensional structure, methods to volumetrically evaluate the lung are important tools in furthering the study of these pathologies.</p> <p>Three-dimensional imaging methodologies, such as computed tomography (CT) and single photon emission computed tomography (SPECT), are used clinically in the diagnosis of lung disease, but results are not commonly quantified. In addition, asthma and COPD develop slowly over time and diagnosis normally takes place after the underlying pathologies are well established. Experimental models in small animals, such as rats and mice, allow for the study of disease pathogenesis in a controlled setting and development of quantitative imaging practices for these models provides translational tools for relating results back to the clinic.</p> <p>In this thesis, CT densitometry and ventilation/perfusion (V/Q) SPECT are explored as methods to investigate models of asthma and COPD. CT densitometry is shown to be capable of quantifying allergic inflammation in an asthma model but is of less use in a model of COPD, predominantly due to the relative amounts of inflammation present. However, V/Q imaging is shown to be quite sensitive to the effects of cigarette smoke in a model of COPD and has been used to better understand how pathologies associated with COPD contribute to gas exchange limitation in the lung.</p> <p>The models, imaging techniques, and analysis methods described in this work provide insight into chronic obstructive lung disease and allow for future investigations into how pathologies effect gas exchange. Further, the characterization of the models described in this thesis allows for drug efficacy studies to be performed, both on established and novel treatments. Future research into asthma and COPD will benefit further from the use of threedimensional imaging methodologies because they provide volumetric information on structure and function and can act as a translational bridge between clinical disease and preclinical animal models.</p> / Doctor of Philosophy (Medical Science)

A comercialização de produtos florestais não madeireiros (PFNMs) popularizou-se como atividade promotora do desenvolvimento socioeconômico de comunidades florestais com baixo impacto ambiental. Há evidências, contudo, de que a exploração possa produzir efeitos ecológicos e socioeconômicos negativos, sugerindo que é necessário monitorar tais iniciativas. A comercialização frequentemente ocorre em áreas remotas e em contextos de pobreza, como é o caso de muitas daquelas da Amazônia brasileira. Desta forma, é necessário que o monitoramento restrinja-se a avaliar os efeitos evidenciados como mais comuns em estudos anteriores. Este estudo revisa e sintetiza as evidências científicas dos efeitos da exploração de PFNMs sobre parâmetros ecológicos e socioeconômicos e, a partir daí, indica aqueles mais relevantes ao monitoramento. O estudo também levanta até que ponto o monitoramento é implementado no contexto da Amazônia brasileira e avalia quais os parâmetros importantes e viáveis de monitoramento neste caso específico. Para isso, foram realizadas revisões sistemáticas da literatura e a consulta a profissionais da área através do método Delphi. Os resultados indicam que efeitos ecológicos negativos são frequentes, principalmente quando se coletam folhas ou cascas. Alterações em órgãos ou processos fisiológicos e a taxa de sobrevivência dos espécimes explorados são parâmetros que devem ser monitorados, em particular quando se coletam frutos e partes vegetativas. Para todos os tipos de PFNMs, o tamanho e a estrutura populacional são parâmetros prioritários ao monitoramento. A riqueza de espécies da comunidade explorada merece atenção, principalmente quando se coletam frutos. Para os aspectos socioeconômicos, efeitos positivos foram mais frequentes que negativos. A contribuição da renda monetária obtida com o comércio na renda total, a regularidade de ingresso desta renda e o papel dos PFNMs como recursos de salvaguarda são parâmetros do capital financeiro prioritários ao monitoramento. Para o capital social, o empoderamento feminino, a coesão de grupo e o acesso aos benefícios gerados pela comercialização devem ser monitorados. Na Amazônia brasileira são poucas as iniciativas de implementação do monitoramento da comercialização de PFNMs. Embora este seja considerado importante, existem dificuldades que derivam principalmente da falta de apoio institucional, políticas de incentivo e de recursos financeiros. Os profissionais participantes do Delphi consideram que os parâmetros ecológicos mais importantes a monitorar neste contexto são o tamanho e a estrutura populacional do recurso explorado, o aumento da taxa de mortalidade, a quantidade total de recurso extraída e a técnica de coleta utilizada. Para os parâmetros econômicos, aspectos do mercado, como o preço pago ao coletor, a demanda e a qualidade do produto, bem como a renda monetária obtida pelos indivíduos são os parâmetros considerados mais importantes. Por fim, para os aspectos sociais, os efeitos na cultura, na qualidade de vida e na organização interna da comunidade foram priorizados. Os profissionais indicam que é viável estabelecer o monitoramento dos parâmetros levantados. / Amazon, non-timber forest products, ecological effects, socioeconomic effects, monitoring.

A comercialização de produtos florestais não madeireiros (PFNMs) popularizou-se como atividade promotora do desenvolvimento socioeconômico de comunidades florestais com baixo impacto ambiental. Há evidências, contudo, de que a exploração possa produzir efeitos ecológicos e socioeconômicos negativos, sugerindo que é necessário monitorar tais iniciativas. A comercialização frequentemente ocorre em áreas remotas e em contextos de pobreza, como é o caso de muitas daquelas da Amazônia brasileira. Desta forma, é necessário que o monitoramento restrinja-se a avaliar os efeitos evidenciados como mais comuns em estudos anteriores. Este estudo revisa e sintetiza as evidências científicas dos efeitos da exploração de PFNMs sobre parâmetros ecológicos e socioeconômicos e, a partir daí, indica aqueles mais relevantes ao monitoramento. O estudo também levanta até que ponto o monitoramento é implementado no contexto da Amazônia brasileira e avalia quais os parâmetros importantes e viáveis de monitoramento neste caso específico. Para isso, foram realizadas revisões sistemáticas da literatura e a consulta a profissionais da área através do método Delphi. Os resultados indicam que efeitos ecológicos negativos são frequentes, principalmente quando se coletam folhas ou cascas. Alterações em órgãos ou processos fisiológicos e a taxa de sobrevivência dos espécimes explorados são parâmetros que devem ser monitorados, em particular quando se coletam frutos e partes vegetativas. Para todos os tipos de PFNMs, o tamanho e a estrutura populacional são parâmetros prioritários ao monitoramento. A riqueza de espécies da comunidade explorada merece atenção, principalmente quando se coletam frutos. Para os aspectos socioeconômicos, efeitos positivos foram mais frequentes que negativos. A contribuição da renda monetária obtida com o comércio na renda total, a regularidade de ingresso desta renda e o papel dos PFNMs como recursos de salvaguarda são parâmetros do capital financeiro prioritários ao monitoramento. Para o capital social, o empoderamento feminino, a coesão de grupo e o acesso aos benefícios gerados pela comercialização devem ser monitorados. Na Amazônia brasileira são poucas as iniciativas de implementação do monitoramento da comercialização de PFNMs. Embora este seja considerado importante, existem dificuldades que derivam principalmente da falta de apoio institucional, políticas de incentivo e de recursos financeiros. Os profissionais participantes do Delphi consideram que os parâmetros ecológicos mais importantes a monitorar neste contexto são o tamanho e a estrutura populacional do recurso explorado, o aumento da taxa de mortalidade, a quantidade total de recurso extraída e a técnica de coleta utilizada. Para os parâmetros econômicos, aspectos do mercado, como o preço pago ao coletor, a demanda e a qualidade do produto, bem como a renda monetária obtida pelos indivíduos são os parâmetros considerados mais importantes. Por fim, para os aspectos sociais, os efeitos na cultura, na qualidade de vida e na organização interna da comunidade foram priorizados. Os profissionais indicam que é viável estabelecer o monitoramento dos parâmetros levantados. / Amazon, non-timber forest products, ecological effects, socioeconomic effects, monitoring.