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Cultural heritage has become a significant part of the cultural economy. Often criticized for its top down approach led by experts, and reflecting a western, elite class interpretation of heritage, the cultural heritage management industry has been trying to place the people at the centre of heritage conservation practices over recent years. This change of paradigm is, in part, due to the recognition of heritage as a significant aspect of everyday life, as well as a fluid yet undeniable attribute of identity and sense of place. In Hong Kong, a fast changing and transient city, the need for heritage conservation has only been recently fully acknowledged. In 2007, the authorities launched a new public-private partnership, known as the Revitalisation Scheme. Mei Ho House was integrated in the first batch of the scheme as the last remain of the first generation of public housing in Hong Kong. The building was transformed into a youth hostel with a museum displaying people's life in the post-war public housing estates. The present thesis investigates this seemingly successful conservation project on the premise that heritage is a dialogue between the material world and the individual. It discusses the legal and cultural context of heritage conservation in Hong Kong, and explores the meaning of vernacular architecture in Hong Kong and the discourse suggested by the museum. The visitors' response is also scrutinized as a significant part in the heritage-making process.

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Les péricytes sont fortement suspectés de jouer un rôle déterminant dans la physiopathologie de l’hypertension artérielle pulmonaire (HTAP), non seulement en raison de leur position et distribution, de leur rôle dans l'homéostasie vasculaire, de leur plasticité et spécificité tissulaire, mais aussi vu leur nette augmentation en nombre autour des artérioles pulmonaires remodelées. Cependant, les mécanismes impliqués dans leur accumulation autour des vaisseaux remodelés ainsi que leur importance dans la mise en place et la progression de l’HTAP restent encore incompris. De plus, nous ne savons pas si les péricytes présentent ou non des anomalies phénotypiques dans l’HTAP.C’est pourquoi ces travaux de doctorat ont visé à : 1) Identifier les possibles anomalies intrinsèques des péricytes provenant de patients HTAP ; 2) Préciser rôle de la voie de signalisation CXCL12/CXCR4/CXCR7 dans l’augmentation de la couverture péricytaire et tester des inhibiteurs de cette voie dans des modèles précliniques d’hypertension pulmonaire (HP) ; 3) Etudier l’impact du pouvoir mésenchymateux des péricytes dans le remodelage vasculaire pulmonaire associé à l’HTAP.Nos données ont permis d’une part de démontrer que les péricytes provenant de patients HTAP possédent des défauts intrinsèques dans les mécanismes de prolifération, de migration et de différenciation cellulaire et que la voie du CXCL12 contribue fortement à l’augmentation anormale de la couverture péricytaire autour des vaisseaux remodelés de patients HTAP. D’autre part, via leur capacité à se différencier en cellules contractiles, nous avons pu démontrer que les péricytes contribuaient directement au remodelage vasculaire pulmonaire.En conclusion, notre étude montre ainsi l’importance du rôle des péricytes pulmonaires dans la progression de l’hypertension artérielle pulmonaire humaine et expérimentale. / Pericytes (PCs) are strongly suspected to play a determining role in the pathophysiology of pulmonary arterial hypertension (PAH), because of their position and distribution, role in vascular homeostasis, versatility and tissue-specificity, but also because they accumulate around remodeled pulmonary arterioles in PAH. However, the underlying mechanisms and their dynamic role in PAH are still unknown. Furthermore, we do not know whether pulmonary PCs are phenotypically and functionally altered in PAH. To answer these questions, our objective were: 1) To examine the phenotypic and functional characteristics of human pulmonary PCs derived from control and PAH patients; 2) To precise the role of the intrinsic abnormalities in the altered phenotype of pulmonary PCs in PAH; 3) To study the dynamic role(s) of pulmonary PCs in preclinical PAH models, especially through modulation of the CXCL12/CXCR4/CXCR7 signaling pathway. Taken together, our findings identify for the first time phenotypic and functional abnormalities of pulmonary PCs in PAH with pathogenetic significance since they increased directly their proliferation, migration and capacity to differentiate in smooth muscle-like cells.

Indiana University-Purdue University Indianapolis (IUPUI) / Bone is a dynamic tissue that is constantly remodeling to repair damage and strengthen regions exposed to loads during everyday activities. However, certain conditions, including long-term unloading of the skeleton, hormonal imbalances, and aging can disrupt the normal bone remodeling cycle and lead to low bone mass and osteoporosis, increasing risk of fracture. While numerous treatments for low bone mass have been devised, dynamic mechanical loading modalities, such as axial loading of long bones and lateral loading of joints, have recently been examined as potential methods of stimulating bone formation. The effectiveness of mechanical loading in strengthening bone is dependent both on the structural and geometric characteristics of the bone and the properties of the applied load. For instance, curvature in the structure of a bone causes bending and increased strain in response to an axial load, which may contribute to increased bone formation. In addition, frequency of the applied load has been determined to impact the degree of new bone formation; however, the mechanism behind this relationship remains unknown. In this thesis, the application of mechanical loading to treat osteoporotic conditions is examined and two questions are addressed: What role does the structural geometry of bone play in the mechanical damping of forces applied during loading? Does mechanical resonance enhance geometric effects, leading to localized areas of elevated bone formation dependent on loading frequency? Curvature in the structure of bone was hypothesized to enhance its damping ability and lead to increased bone formation through bending. In addition, loading at frequencies near the resonant frequencies of bone was predicted to cause increased bone formation, specifically in areas that experienced high principal strains due to localized displacements during resonant vibration. To test the hypothesis, mechanical loading experiments and simulations using finite element (FE) analysis were conducted to characterize the dynamic properties of bone. Results demonstrate that while surrounding joints contribute to the greatest portion of the damping capacity of the lower limb, bone absorbs a significant amount of energy through curvature-driven bending. In addition, results show that enhanced mechanical responses at loading frequencies near the resonant frequencies of bone may lead to increased bone formation in areas that experience the greatest principal strain during vibration. These findings demonstrate the potential therapeutic effects of mechanical loading in preventing costly osteoporotic fractures, and explore characteristics of bone that may lead to optimization of mechanical loading techniques. Further investigation of biomechanical properties of bone may lead to the prescribing of personalized mechanical loading treatments to treat osteoporotic diseases.

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Objectif : L'hypertension est associée à une hyperplasie cardiovasculaire, un taux de renouvellement cellulaire accéléré et une diminution de la longueur des télomères. Nous avons postulé que le renversement de l’hyperplasie par apoptose sélective observé avec les inhibiteurs du système rénine-angiotensine (iSRA) chez le rat spontanément hypertendu (SHR) est associé à une modulation de la longueur des télomères cardiovasculaires. Méthodes : La mesure relative du poids du ventricule gauche (VG) et son contenu en ADN ont été mesurés. Dans l’aorte, l’hypertrophie a été mesurée histologiquement et l’hyperplasie par décompte des cellules de muscle lisse (CML). La longueur des télomères (TRF) a été mesurée par immunobuvardage de type Southern. Ces mesures ont été effectuées chez des rats SHR traités avec un placebo, un iSRA (énalapril ou losartan) ou l'hydralazine pendant 21 jours, ainsi que chez les rats normotendus Wistar-Kyoto (WKY). Résultats : Les iSRA ont partiellement normalisé le contenu en ADN dans le VG et complètement normalisé le décompte cellulaire des CML dans l’aorte. Comparativement aux rats WKY, les SHR placebo ont montré un plus haut pourcentage de TRF courts dans le ventricule gauche (50,2% vs 64,6%; p<0,05) ainsi qu’une longueur moyenne des TRF plus courte (62,6 Kb vs 57,1Kb; p<0,05). Ces différences ont été abolies par l'énalapril et le losartan mais pas par l'hydralazine. Dans l’aorte, les résultats préliminaires n’ont pas révélé de différence significative. Ils suggèrent que les rats SHR-placebo ont des télomères plus longs que les rats WKY et que les inhibiteurs du SRA tendent à normaliser cette différence. Conclusion : Les iSRA ont normalisé la longueur des télomères dans le VG. Nous spéculons que les iSRA agissent comme agents sénolytiques et éliminent préférentiellement les fibroblastes cardiaques avec télomères courts. Dans l’aorte, d’autres études sont requises afin de confirmer une possible régulation différentielle spécifique à ce tissu. / Objective: Hypertension is associated with cardiovascular hyperplasia, an increased cell turnover and a decrease in telomere length. We postulated that the reversal of hyperplasia by selective apoptosis observed with renin-angiotensin inhibitors (RASi) in the spontaneously hypertensive rat (SHR) is associated with a modulation of cardiovascular telomere length. Methods: Relative weight of the left ventricle (LV) and its DNA content were measured. In the aorta, hypertrophy was measured histologically and hyperplasia was measured through smooth muscle cell (SMC) count. Telomere restriction fragment (TRF) length was measured using Southern blot. Those measures were taken on SHR treated with either a placebo, a RAS inhibitor (enalapril or losartan) or hydralazine for 21 days, as well as on Wistar-Kyoto (WKY) normotensive rats. Results: RAS inhibitors partially normalized DNA content in the LV and completely normalized the SMC count in the aorta. Comparatively to the WKY rats, SHR-placebo displayed a higher percentage of short TRF in the LV (50,2% vs 64,6%; p<0,05) as well as a shorter mean TRF length (62,6 Kb vs 57,1Kb; p<0,05). Those differences were eliminated by enalapril and losartan, but not with hydralazine. In the aorta, preliminary results did not yield to significant differences. They suggest that SHR-placebo have longer telomeres than WKY rats and that RAS inhibitors tend to normalize this difference. Conclusion: RAS inhibitors normalized telomere length in the LV. We speculate that RAS inhibitors act as senolytic agents and preferentially eliminate cardiac fibroblasts with short telomeres. In the aorta, more studies are required to confirm the possible differential regulation specific to this tissue.

Indiana University-Purdue University Indianapolis (IUPUI) / The first part of the study describes the development of a microCT based engineering model to study orthodontic responses. The second part investigated the relationship between orthodontic stimulus, root resorption and bone modeling. It was hypothesized that stress magnitudes are insufficient to portray the mechanical environment and explain the clinical response; directions also play a role. An idealized tooth model was constructed for finite element analysis. The principal stress magnitudes and directions were calculated in tipping and translation. It was concluded that within the same region of root, PDL and bone, there can be compression in one structure, tension in another. At a given point in a structure, compression and tension can coexist in different directions. Magnitudes of compression or tension are typically different in different directions. Previously published data presenting only stress magnitude plots can be confusing, perhaps impossible to understand and/or correlate with biological responses. To avoid ambiguities, a reference to a principal stress should include its predominant direction. Combined stress magnitude/direction results suggest that the PDL is the initiator of mechanotransduction. The third part of this project tested the role of the P2X7 receptor in the dentoalveolar morphology of C57B/6 mice. P2X7R KO (knockout) mice were compared to C57B/6 WT to identify differences in a maxillary molar and bone. Tooth dimensions were measured and 3D bone morphometry was conducted. No statistically significant differences were found between the two mouse types. P2X7R does not have a major effect on alveolar bone or tooth morphology. The final part examines the role of the P2X7 receptor in a controlled biomechanical model. Orthodontic mechanotransduction was compared in wild-type (WT) and P2X7R knock-out (KO) mice. Using Finite Element Analysis, mouse mechanics were scaled to produce typical human stress levels. Relationships between the biological responses and the calculated stresses were statistically tested and compared. There were direct relationships between certain stress magnitudes and root resorption and bone formation. Hyalinization and root and bone resorption were different in WT and KO. Orthodontic responses are related to the principal stress patterns in the PDL and the P2X7 receptor plays a significant role in their mechanotransduction.

Indiana University-Purdue University Indianapolis (IUPUI) / Rationale: Tissue remodeling and complement activation are asthma hallmarks. Type V collagen [col(V)], a cryptic antigen, becomes exposed during lung remodeling. IL-17 is key to anti-col(V) immunity, and regulates complement activation. We have reported that col(V)-induced tolerance down regulates IL-17 and prevents immune-mediated lung diseases. Objectives: Determine a role for anti-col(V) immunity in asthma. Methods: Serum anti-col(V) antibodies were measured in asthma patients, and immunohistochemistry utilized to detect interstitial col(V) in fatal asthma. Balb/c mice were tolerized with col(V) prior to sensitization with ovalbumin (OVA), and subsequent OVA intranasal challenge. Airway hyper-responsiveness (AHR) to methacholine was measured; and RT-PCR utilized to determine local Il17 transcripts. Bronchoalveolar lavage levels of C3a¸ C5a and OVA-specific IgE were measured; and immunohistochemistry utilized to detect expression of complement regulatory proteins, expression, CD46/Crry and CD55, in lung tissue. Results: Compared to normal subjects, anti-col(V) antibodies were increased in asthmatics; and interstitial col(V) was over expressed in fatal asthma. OVA-induced AHR up regulated anti-col(V) antibodies systemically, and increased OVA-specific IgE and C3a in BAL, and parenchymal Il17 transcripts. Col(V)-induced tolerance abrogated AHR, down regulated OVA-induced T cell proliferation, as well as total and OVA-specific IgE, C3a, IL-17 expression and tracheal smooth muscle contraction. Crry/CD46 and CD55, key to preventing complement activation, were down regulated on goblet cells in murine allergic airway disease. Conclusions: Anti-col(V) immunity correlates with asthma pathogenesis, and col(V)-induced tolerance may be a novel therapeutic for asthma. Decreased expression of Crry/CD46 and CD55 on goblet cells may in part account for complement activation in asthma.