Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Dans l'industrie nucléaire, les composants en alliages de zirconium (Zr) sont utilisés comme éléments de structure dans les assemblages combustibles. La fabrication de ces éléments, leur utilisation en Réacteur à Eau Pressurisée (REP) et leur stockage avant retraitement induisent, entre autres, des sollicitations thermo-mécaniques complexes. Ce travail, grâce à une approche expérimentale multi-échelles, propose de mieux préciser les mécanismes de déformation qui sont à considérer. Pour cela, nous avons mené, sur des échantillons prélevés sur des composants en alliage de Zr destinés à être utilisés en REP, des essais mécaniques (fluage, traction, relaxation) et, d'autre part, des caractérisations microstructurales. Des essais de fluage multiaxial ont ainsi permis de mettre en évidence une anisotropie de comportement, dont l'origine physique a été montrée au moyen d'analyses en diffraction des électrons rétrodiffusés (EBSD) et d'observations en Microscopie Electronique en Transmission (MET). Par une démarche similaire, nous avons aussi identifié la nature des mécanismes accommodant la déformation à l'échelle du grain et à celle du polycristal. Ainsi, les incompatibilités de déformation intergranulaires et les cinétiques d'écoulement viscoplastiques identifiées expérimentalement s'expliquent par l'intervention de processus de traînage d'espèces en solutions par les dislocations, ainsi que l'activation locale de vieillissement dynamique. Enfin, nous avons esquissé des pistes pour l'utilisation de ces résultats dans des modélisations numériques. / In the nuclear industry, zirconium (Zr) based alloys are used as core structural materials in Pressurized Water Reactors (PWRs). The manufacturing of those components, and their environment during or after their use in PWRs induce complex thermo-mechanical loadings. This work, through a multi-scale experimental approach, proposes to focus on the deformation mechanisms that occur during those loadings. Using samples taken from Zr alloy components, we carried out different mechanicals tests (creep tests, tensile tests, relaxation tests) and microstructural characterizations. Results of multiaxial creep tests were correlated to Transmission Electron Microscope (TEM) observations and Electron BackScattered Diffraction (EBSD) analyses. Therefore, the macroscopic creep anisotropy was related to the physical mechanisms observed at the dislocation scale and during mesoscopic measurements. Our conclusions also show that the viscoplastic properties obtained experimentally match a control of dislocation mobility by solute species dragging processes. Further, the intergranular strain incompatibilities that we observed could be explained by local activations of dynamic strain ageing mechanisms. Finally, we used our results to suggest improvements on physically-based modelling techniques.

The Receptor Tyrosine Kinase (RTK) Met, overexpressed or mutated in cancer, plays a major role in cancer progression and represents an attractive target for cancer therapy. This study aimed to investigate whether PI3K plays a role in Met oncogenicity. Three cell models were used: (i) NIH3T3 cells expressing WT Met or the constitutively active mutant M1268T Met; (ii) U87MG glioblastoma cells, with endogenous WT Met constitutively activated due to an autocrine loop; (iii) A549 lung cancer cells expressing endogenous WT Met, activated upon binding exogenous HGF. Met dependent Rac1 translocation to the plasma membrane, actin cytoskeleton organisation, cell migration, anchorage independent growth in soft agar and tumour growth were studied in the presence of inhibitors of pan-PI3K / mTOR, various PI3K Class I isoforms, mTOR or Akt, or following siRNA knock-down of PI3K isoforms. We report that PI3K class I (but not class III) regulates Met dependent cell migration. The PI3K class I isoforms required varies among the cell models. Interestingly, the combined inhibition of all p110 Class I isoforms lead to the strongest reduction of Met dependent cell migration. Met dependent phosphorylation of Akt, an effector of PI3K class I, is reduced upon endocytosis inhibition, suggesting that Met signals to PI3K Class I on endosomes. Our results indicate that mTOR is responsible for Met dependent anchorage independent growth and tumour growth in vivo. Surprisingly, PI3K class I (and class III) are not required. Moreover, Rac1 is required for Met dependent mTOR activation, (phosphorylation of mTORC1's effector, p70 S6K) subcellular translocation of mTOR and anchorage independent growth. Finally, our results suggest that this Met-Rac1- mTOR pathway occurs on endosomes. Thus while PI3K class I regulates Met dependent cell migration, mTOR regulates Met driven anchorage independent growth and in vivo tumorigenesis. Thus PI3K Class I / mTOR may be targeted in Met driven cancers.

Introduction: Basal-like (BL) breast cancer is an aggressive sub-type of breast cancer for which there is no targeted systemic therapy. C-Met is a receptor tyrosine kinase implicated in breast cancer. Clinical trials assessing the efficacy of anti-c-Met therapy are underway, yet few studies have analysed the clinical significance of c-Met expression and/or activation in breast cancer, in particular whether there is a correlation with molecular sub-type. The aims of this study are: 1) to establish the clinical significance of c-Met expression in invasive breast cancer, 2) evaluate the novel proximity ligation assay (PLA) as a method of measuring c-Met activation and 3) address the effect of hepatocyte growth factor (HGF)-mediated c-Met phosphorylation on migration and protein expression in cell lines representative of the BL sub-type. Methods: Immunohistochemistry for c-Met was performed on 1455 cases of breast cancer using tissue microarray (TMA) technology. The PLA was performed on TMAs constructed from 181 breast cancers. C-Met expression and the PLA product were correlated with clinico-pathological parameters and survival. The effects of HGF on cell migration and protein expression were assessed using migration assays, western blots and immunofluorescent studies. Results: C-Met expression was independently associated with BL breast cancer (odds ratio = 6.44, 95% confidence interval (CI) = 1.74-23.78, p = 0.005) and reduced overall survival (hazard ratio = 1.81, 95% CI = 1.07-3.06), p = 0.026). The PLA signal was not associated with molecular sub-type or survival. HGF stimulation was associated with a significant increase in BL cell migration (p < 0.01) but no evidence of epithelial-mesenchymal transition was observed. Conclusion: My findings suggest BL breast cancer patients should be included in future trials of anti-c-Met therapy. Further work is necessary to establish the prognostic utility of the PLA as a measure of c-Met activation and the mechanisms driving HGF-mediated cell migration.

Submitted by Sara Ribeiro (sara.ribeiro@ucb.br) on 2017-08-18T20:23:36Z No. of bitstreams: 1 LuliNeriRiccettoDissertacao2016.pdf: 493938 bytes, checksum: 41140ac2e43a963845f7c3f5eb39a172 (MD5) / Approved for entry into archive by Sara Ribeiro (sara.ribeiro@ucb.br) on 2017-08-18T20:23:52Z (GMT) No. of bitstreams: 1 LuliNeriRiccettoDissertacao2016.pdf: 493938 bytes, checksum: 41140ac2e43a963845f7c3f5eb39a172 (MD5) / Made available in DSpace on 2017-08-18T20:23:52Z (GMT). No. of bitstreams: 1 LuliNeriRiccettoDissertacao2016.pdf: 493938 bytes, checksum: 41140ac2e43a963845f7c3f5eb39a172 (MD5) Previous issue date: 2016-01-01 / This paper aims at analyzing gastronomy as a non-verbal communication process and the relations established through cooking and eating together. It is assumed that a bond is created between cook and diner and that there is a discourse between them, being the food the mediator of several possible kinds of relations. Thus, emotional relations arising from these proceedings are investigated, inquiring the proposed notion: affective gastronomy. In order to work this object, experiments were performed and show that communication through gastronomy is able to affect relations. my as a non-verbal communication process and the relations established through cooking and eating togeA brief theoretical review on the peculiar relation established between human beings and food is carried out, as well as communication as an event and phenomenon that initially involves the body. The concept of ???affection??? as an important aspect of communication is investigated as proposed by Cyrulnik and Maffesoli. The notion of met??poro as defended by Ciro Marcondes is applied to bring all these aspects together. It is believed that gastronomic language is demonstrated by displays of affection. / Prop??e-se analisar a gastronomia como processo de comunica????o n??o-verbal e as rela????es que se estabelecem atrav??s da culin??ria e da comensalidade. Sup??e-se que um v??nculo se cria entre quem faz a comida e quem a come; existindo um discurso entre cozinheiro e comensal, onde a comida ?? a mediadora de rela????es que podem ser de v??rios tipos. Assim, investigam-se as rela????es afetivas decorrentes desses processos, indagando a no????o proposta: gastronomia afetiva. Para trabalhar esse objeto, foram feitos experimentos que mostram que a comunica????o, atrav??s da gastronomia, ?? capaz de afetar rela????es. Realiza-se uma breve revis??o te??rica sobre a peculiar rela????o ser humano x alimento e sobre a comunica????o como acontecimento e fen??meno que envolve inicialmente o corpo. Investiga-se o conceito de ???afeto??? proposto por Cyrulnik e Maffesoli, como um aspecto importante da comunica????o. Para a costura de todos esses aspectos, utiliza-se a no????o de met??poro proposta por Ciro Marcondes. Acredita-se que a comunica????o gastron??mica se d?? por manifesta????es de afetividade.

Timely activation of the rapid response team (RRT) depends on the nurse's willingness and ability to make a rapid decision. The practice-focused questions for this DNP project sought to identify barriers that contribute to delays in activating the RRT when needed in medical-surgical patients. The self-efficacy theory was the guiding theory and was used to examine self-confidence and performance along with Donabedian's health care model. Qualitative data were obtained through focus groups and identified 2 prominent thematic barriers among nurses with less than 3 years' experience: a lack of self-confidence and the of lack of knowledge and experience. Results of a chart review included 34 charts to determine if the RRT were called appropriately and were inconclusive. Finally, an 11 item survey with 9 demographic questions showed a statistically significant difference on the summed survey score between nurses with less than 3 years of experience and more tenured nurses, indicating a lack of perceived support, self-confidence, and knowledge among the nurses with less than 3 years of experience (Pearson chi square = 7.403 with 2 df and p = .025). Results were presented to leaders at the site and the recommendations resulting from these observations include the use of high-fidelity simulation education. Nurse educators and senior leadership from the medical surgical units agreed to accept the recommendations and proceed with developing an educational solution to address the barriers. Building knowledge, skills and self-confidence in nurses reduces the barriers to effective use of the RRT, and results in better outcomes for hospitalized medical-surgical patients, a positive social change.

Medulloblastoma is the most common malignant paediatric brain tumour. Similar to other tumours, medulloblastoma pathogenesis involves abnormal regulation of several developmental growth pathways. As my thesis project, I studied the effects of aberrant HGF/MET signalling on medulloblastoma formation in two ways. In my first objective, I investigated the role that mutations play in activated HGF/MET signalling in medulloblastoma by searching for mutations in HGF/MET pathway genes, SPINT1, SPINT2, and MET, within primary medulloblastoma specimens. This screen identified several single nucleotide polymorphisms (SNPs) and two novel variations, one in each SPINT1 and SPINT2 genes. In my second objective, I generated a transgenic mouse model with cerebellar-specific aberrant MET signalling. These mice developed extensive cerebellar abnormalities but formed no tumours. These results indicate that mutations in the HGF/MET pathway components alone are not sufficient to initiate medulloblastoma formation and must coincide with additional genetic insults to promote tumour formation, maintenance, and progression.

Medulloblastoma is the most common malignant paediatric brain tumour. Similar to other tumours, medulloblastoma pathogenesis involves abnormal regulation of several developmental growth pathways. As my thesis project, I studied the effects of aberrant HGF/MET signalling on medulloblastoma formation in two ways. In my first objective, I investigated the role that mutations play in activated HGF/MET signalling in medulloblastoma by searching for mutations in HGF/MET pathway genes, SPINT1, SPINT2, and MET, within primary medulloblastoma specimens. This screen identified several single nucleotide polymorphisms (SNPs) and two novel variations, one in each SPINT1 and SPINT2 genes. In my second objective, I generated a transgenic mouse model with cerebellar-specific aberrant MET signalling. These mice developed extensive cerebellar abnormalities but formed no tumours. These results indicate that mutations in the HGF/MET pathway components alone are not sufficient to initiate medulloblastoma formation and must coincide with additional genetic insults to promote tumour formation, maintenance, and progression.

El sarcoma de Kaposi (SK) es una enfermedad angioproliferativa con cuatro formas clínico-epidemiológicas: clásica (SK-C), africana endémica, relacionada con fármacos inmunosupresores y relacionada con el síndrome de inmunodeficiencia adquirida (SK-SIDA). La afectación del SK es generalmente cutánea, pero en los casos agresivos puede diseminarse a localizaciones extracutáneas. En la piel, las lesiones se clasifican clínicopatológicamente en máculas, placas y tumores de acuerdo con su progresión y severidad. El SK parece iniciarse como una proliferación vascular reactiva debida a una red de citocinas alterada, mientras que en estadios avanzados, se comporta como una neoplasia multifocal.El diferente comportamiento biológico del SK de acuerdo con sus presentaciones epidemiológicas y estadios puede estar relacionado con la presencia de alteraciones específicas en los mecanismos que controlan el crecimiento y desarrollo tumoral, como la sobreestimulación de citocinas y de factores de crecimiento angiogénicos o alteraciones en las oncoproteínas que controlan la proliferación celular y la apoptosis. Estas alteraciones podrían ofrecer los estímulos neoplásicos necesarios para el desarrollo, progresión y, en definitiva, un comportamiento más agresivo del SK.El factor de crecimiento hepatocitario (HGF) es una citocina angiogénica pleiotrópica que está sobreexpresada en cánceres humanos invasivos y puede actuar como factor de progresión tumoral, estimulando la angiogénesis y la invasividad de las células tumorales. Estas respuestas son transducidas a través del receptor c-Met. El HGF estimula la proliferación de las células fusiformes cultivadas de lesiones humanas de SK, y además las células del SK sintetizan y secretan HGF y expresan c-Met, creando un rizo de retroalimentación para la proliferación tumoral y la neovascularización. Hemos estudiado la expresión del c-Met en diferentes estadios histológicos de lesiones de SK-C y SK-SIDA, observando que la intensidad de tinción de c-Met fue mayor en los tumores que en las placas, de forma que el HGF se comporta como un factor de progresión en el SK.EL HHV-8, el factor etiológico del SK, codifica la v-ciclina, que formando complejo con la cinasa dependiente de ciclina (CDK) 6, contribuye a la fosforilación y degradación mediada por proteasoma del inhibidor de las cinasas dependientes de ciclina p27KIP1. La p27KIP1 regula negativamente la proliferación celular uniéndose e inhibiendo a los complejos ciclina-CDK de fase G1. Por otro lado, la infrarregulación de la expresión de la p27KIP1 parece facilitar el desarrollo tumoral y la diseminación metastásica; por ello la p27KIP1 ha sido considerada como un factor pronóstico independiente en una gran variedad de neoplasias humanas. Aunque la naturaleza neoplásica del SK todavía es controvertida, se ha demostrado repetidas veces que en algunos pacientes el SK puede comportarse como una neoplasia maligna y seguir un curso ominoso. Para determinar si la disminución de los niveles de la p27KIP1 está también relacionada con un comportamiento más agresivo del SK, decidimos investigar la inmunoreactividad de la p27KIP1 en biopsias de SK. De este modo, intentamos determinar si la disminución de los niveles de expresión de la p27KIP1 está relacionada con la afectación extracutánea en el SK, como ocurre en otras neoplasias cuando metastatizan. La media de porcentajes de células positivas para p27KIP1 era significativamente mayor en las biopsias de lesiones cutáneas y en las máculas-placas que en las lesiones extracutáneas y en los tumores respectivamente. Estos resultados apoyan la hipótesis de que la disminución de los niveles de la p27KIP1, que pueden ser producidos por la infección por el HHV-8, facilitan la progresión del SK a través de sus estadios histopatológicos y su eventual extensión extracutáneaEstudios recientes han demostrado que la degradación de la p27KIP1 a través de la vía ubicuitin-proteasoma está mediada por el complejo SCF/ p45SKP2 y por su receptor específico de sustrato F-box p45SKP2. La p45SKP2 está frecuentemente sobreexpresada en células transformadas, induce la fase S en células quiescentes y se sospecha que es un protooncogen en tumores humanos. De hecho, se ha determinado una asociación entre el incremento de los niveles de la p45SKP2 y la disminución de los niveles de la p27KIP1 en neoplasias epiteliales. Hemos estudiado si la expresión de la p45SKP2 está alterada en las lesiones agresivas del SK y su relación con la infrarregulación de la p27KIP1, sexo e infección por el VIH. La sobreexpresión nuclear de la p45SKP2 estaba presente en todos los estadios del SK, estando significativamente incrementada en los tumores cutáneos y en las lesiones extracutáneas en comparación con la máculas y placas. No se identificaron diferencias estadísticamente significativas en relación con el sexo y estatus VIH de los pacientes, y el análisis de regresión no mostró correlación entre la p45SKP2 y la p27KIP1. Estos hallazgos sugieren que la p45SKP2 está involucrada en el SK, no sólo promoviendo la degradación de la p27KIP1, sino también a través de otros mecanismos todavía desconocidos. / Kaposi's sarcoma (KS) is an angioproliferative disease with four clinical-epidemiological forms: classic (C-KS), African-endemic, immunosuppressive drug-related and acquired immune deficiency syndrome-related (AIDS-KS). KS involvement is usually limited to the skin, but in aggressive cases it may disseminate to extracutaneous locations. In the skin, lesions are clinicopathologically classified into macules, plaques and tumours in agreement with their progression in severity. KS seems to begin as a reactive vascular proliferation due to an unbalanced cytokine network, whereas in advanced stages, it behaves as a multifocal neoplasm.The different biological behavior of KS according to its epidemiological presentations and stages might be related to the presence of specific alterations in the mechanisms controlling tumor growth and development, such as cytokine or angiogenic growth factor overstimulation or alterations of the oncoprotein networks that control cell proliferation and apoptosis. These alterations would provide neoplastic stimuli for the development, progression, and aggressive behaviour of KS. Hepatocyte growth factor (HGF) is a pleiotropic angiogenic cytokine that is overexpressed in invasive human cancers and may function as a tumor progression factor, stimulating tumour cell invasiveness and angiogenesis. These responses are transduced through the c-Met receptor. HGF stimulates proliferation of spindle cells cultured from human KS lesions, and KS cells synthesize and secrete HGF and express c-Met, thus providing an autocrine loop for tumour proliferation and neovascularization. We have studied the expression of c-Met in different histological stages of AIDS-associated and classic KS lesions. The staining intensity of c-Met was stronger in tumours than in plaques showing that HGF would be a progression factor in KS. HHV-8, the KS'etiologic factor, encoded v-cyclin, through its complexing with cyclin-dependent kinase (CDK) 6, contributes to the phosphorylation and proteasome-mediated degradation of p27KIP1, a cyclin-dependent kinase inhibitor. P27KIP1 regulates negatively cell proliferation by binding and inhibiting G1 cyclin-CDK complexes. On the other hand, down-regulation of p27KIP1 expression seems to facilitate tumour development and metastatic dissemination; then p27KIP1 has been considerated as an independent prognostic factor in a variety of human neoplasms. Although the neoplastic nature of KS remains controversial, it has been repeatedly demonstrated that in some patients KS may behave as a malignant neoplasm and follow an ominous course. To determine whether decreased p27KIP1 levels are also related to more aggressive behaviour in KS, it was decided to investigate p27KIP1 immunoreactivity in KS biopsy specimens. Thereby, we sought to determine whether the decrease in p27KIP1 expression levels is related to extracutaneous involvement in KS, as is the case in several other types of neoplasms when they metastasize. The mean percentages of p27KIP1-positive cells were significantly higher in biopsy specimens from skin lesions and in macules-plaques than in those from extracutaneous locations and tumours respectively. These results lend support to the hypothesis that decreased levels of p27KIP1, which may have been brought about by HHV-8 infection, play a role in KS progression through its various histopathological stages, to its eventual extracutaneous spread.Recent studies have demonstrated that p27KIP1 degradation through the ubiquitin-proteasome pathway is mediated by the SCF/p45SKP2 complex and by the substrate-specific receptor of this complex, the F-Box protein p45SKP2. P45SKP2 is frequently over-expressed in transformed cells, induces S phase in quiescent cells and is a suspected proto-oncogene in human tumours. In fact, there are recent reports of increased levels of p45SKP2 in association with reduced p27KIP1 levels in epithelial neoplasms. We have studied of whether p45SKP2 expression is altered in aggressive lesions of KS and its relation to p27KIP1 down-regulation, gender and HIV infection. P45SKP2 nuclear over-expression was present in all KS stages, being significantly increased in skin tumours and extracutaneous lesions as compared with macules and plaques. No statistically significant differences were found in regard to patients´ sex and HIV status and regression analysis failed to show a correlation among p45SKP2 and p27KIP1. These findings suggest that p45SKP2 is involved in KS, not only by promoting the degradation of p27KIP1 but also through other mechanisms still unknown.