published_or_final_version / abstract / toc / Earth Sciences / Master / Master of Philosophy

Yes / Background - Previous studies have demonstrated that a number of HOX genes, a family of transcription factors with key roles in early development, are up-regulated in head and neck squamous cell carcinoma (HNSCC) and other cancers. The loci of several Homeobox (HOX) genes also contain microRNAs (miRs), including miR-196a. Methods - Global miR expression and expression of all 39 HOX genes in normal oral keratinocytes (NOKs), oral pre-malignant (OPM) and HNSCC cells was assessed by expression microarray and qPCR and in tissues by immunohistochemistry (IHC) and qPCR of laser microdissected (LCM) tissues. Expression of miR196a and HOXB9 was reduced using anti-miR-196a and siRNA, respectively. Expression microarray profiles of anti-miR196a and pre-miR196a transfected cells were compared to parental cells in order to identify novel targets of miR- 196a. Putative miR196a targets were validated by qPCR and were confirmed as binding to the 3’UTR of miR196a by a dual luciferase reporter assay combined with mutational analysis of the miR-196a binding site. Results - miR-196a and HOXB9 are highly expressed in HNSCC compared to NOKs, a pattern also seen in HNSCC tissues by HOXB9 IHC and qPCR of miR-196a in LCM tissue. Knock-down of miR-196a expression decreased HNSCC cell migration, invasion and adhesion to fibronectin, but had no effect on proliferation. Furthermore, knock-down of HOXB9 expression decreased migration, invasion and proliferation but did not alter adhesion. We identified a novel primary mRNA transcript containing HOXB9 and miR196a-1 as predicted from in-silico analysis. Expression array analysis identified a number of miR196a targets, including MAMDC2 and HOXC8. We confirmed that MAMDC2 is a novel miR-196a target using a dual luciferase reporter assay with the effect abolished on mutation of the binding site. Conclusions - These results show that miR-196a and HOXB9 are overexpressed, perhaps co-ordinately, as HNSCC develops and exert a pro-tumourigenic phenotype in HNSCC and OPM cells.

Como em diversos tumores sólidos, no câncer de cabeça e pescoço (HNSCC) a presença de metástases é um importante fator de mal prognóstico. Até o momento, estudos indicam que, no microambiente inflamatório tumoral, a estimulação com o Fator de Necrose Tumoral Alpha (TNF-?) leva à ativação de diferentes vias moleculares, como a via do Fator Nuclear Kappa-B (NF-kB) e PI3K/AKT, que inibem GSK3? e consequentemente, promovem a estabilização e translocação nuclear de SNAIL e betacatenina. De um modo geral, em diversos tipos de câncer, enquanto beta-catenina tem ação em promover a proliferação celular, membros da família SNAIL são capazes de induzir o processo de transição epitélio-mesenquimal (EMT). Sabe-se que os eventos de EMT estão envolvidos tanto na iniciação de metástases quanto na geração de célulastronco tumorais (CSCs), que por sua vez estão associadas à falha terapêutica e recidiva, devido à características que lhe conferem resistência aos tratamentos convencionais. Ao silenciar a expressão gênica de modo pós-transcricional, microRNAs (miRs) tem sido associados à regulação tanto da EMT quanto da geração de CSCs. Com uso da abordagem de High-Content Screening (HCS, análise celular multiparamétrica quantitativa por microscopia automatizada), buscamos investigar a capacidade de um grupo de 30 miRs humanos, muitos deles envolvidos em vias inflamatórias e na pluripotência, em modular aspectos relacionados a sobrevivência celular e EMT, em uma linhagem celular derivada de HNSCC (FADU) sob estímulo inflamatório. Inicialmente, avaliamos o potencial do TNF-? em modular parâmetros morfométricos, bem como a presença/localização de proteínas relacionadas com a EMT e capacidade migratória. Posteriormente, avaliamos o efeito de moléculas miméticas dos miRs em suprimir ou potencializar a sobrevivência celular e EMT em células estimuladas com TNF-?, seguido da identificação de transcritos alvos preditos (bem como das vias de sinalização enriquecidas para estes alvos) comumente alvejados por grupos de miRs que levaram a alterações multiparamétricas similares. De modo geral, miRs que alvejaram RELA e AKT2/AKT3 foram responsáveis pela redução na proliferação celular e EMT, enquanto o oposto foi observado em miRs que alvejaram GSK3B e ARHGAP5 (inibidor de RhoA). O silenciamento por siRNAs específicos contra RELA e CTNNB1, causou à redução na sobrevivência celular, enquanto que o silenciamento de AKT1 e CTNNB1 levou à redução na expressão proteica de SNAIL/SLUG. Finalmente, o silenciamento de RELA, AKT1, GSK3B e CTNNB1 levou a redução na sobrevivência celular e indução a apoptose mesmo na ausência de estimulação com TNF-?. Como um todo, nós demonstramos que a abordagem de HCS permitiu a identificação de miRs com efeitos fenotípicos similares (no contexto de proliferação e EMT) e que, a predição de alvos compartilhados por estes miRs, levou à identificação de alvos e vias de sinalização relevantes do ponto de vista terapêutico. / Like many solid cancers, in head and neck cancer (HNC) the presence of metastases is an important factor of poor prognosis. To date, studies indicate that, in the tumor inflammatory microenvironment, stimulation with Tumor Necrosis Factor Alpha (TNF-?) leads to the activation of different molecular pathways, such as the Nuclear Factor-Kappa B (NF-kB) and PI3K/AKT pathway, inhibiting GSK3? and the degradation of SNAIL and beta-catenin, stabilizing them promoting their nuclear translocation. In general, in several types of cancer, while beta-catenin acts to promote cell proliferation, members of the SNAIL family induce the epithelial-mesenchymal (EMT) transition process. It is known that EMT events are involved both in the initiation of metastases and generation of cancer stem cells (CSCs), which in turn are associated with therapeutic failure and relapse, due to its properties that confer resistance to conventional treatments. By silencing gene expression in a post-transcriptional fashion, microRNAs (miRs) have been associated with the regulation of both EMT and CSCs generation. Using the HighContent Screening (HCS) approach, we sought to investigate the ability of a group of 30 human miRs, many of them involved in inflammatory pathways and pluripotency, to modulate aspects related to cell survival and EMT, in a HNSCC-derived cell line (FADU) under inflammatory stimuli. Initially, we evaluated the potential of TNF-? in modulating morphometric parameters, as well as the presence/location of EMT-related proteins and migratory capacity. Subsequently, we evaluated the effect of miRs mimetic molecules on suppressing or potentiating cell survival and EMT in TNF-?-stimulated cells, followed by the identification of predicted target transcripts (as well as signaling pathways enriched for these targets) commonly targeted by groups of miRs that led to similar multiparametric changes. Overall, miRs that targeted RELA and AKT2/AKT3 were responsible for the reduction in cell proliferation and EMT, while the opposite was observed in miRs that targeted GSK3B and ARHGAP5 (RhoA inhibitor). Gene silencing by specific siRNAs against RELA and CTNNB1 caused a reduction in cell survival, while silencing of AKT1 and CTNNB1 led to reduced protein expression of SNAIL/SLUG. Finally, the silencing of RELA, AKT1, GSK3B and CTNNB1 led to a reduction in cell survival and induction of apoptosis even in the absence of TNF-? stimulation. As a whole, we demonstrated that the HCS approach allowed the identification of miRs with similar phenotypic effects (in the context of proliferation and EMT) and that the prediction of targets shared by these miRs led to the identification of relevant targets and signaling pathways from the therapeutic point of view.

Como em diversos tumores sólidos, no câncer de cabeça e pescoço (HNSCC) a presença de metástases é um importante fator de mal prognóstico. Até o momento, estudos indicam que, no microambiente inflamatório tumoral, a estimulação com o Fator de Necrose Tumoral Alpha (TNF-?) leva à ativação de diferentes vias moleculares, como a via do Fator Nuclear Kappa-B (NF-kB) e PI3K/AKT, que inibem GSK3? e consequentemente, promovem a estabilização e translocação nuclear de SNAIL e betacatenina. De um modo geral, em diversos tipos de câncer, enquanto beta-catenina tem ação em promover a proliferação celular, membros da família SNAIL são capazes de induzir o processo de transição epitélio-mesenquimal (EMT). Sabe-se que os eventos de EMT estão envolvidos tanto na iniciação de metástases quanto na geração de célulastronco tumorais (CSCs), que por sua vez estão associadas à falha terapêutica e recidiva, devido à características que lhe conferem resistência aos tratamentos convencionais. Ao silenciar a expressão gênica de modo pós-transcricional, microRNAs (miRs) tem sido associados à regulação tanto da EMT quanto da geração de CSCs. Com uso da abordagem de High-Content Screening (HCS, análise celular multiparamétrica quantitativa por microscopia automatizada), buscamos investigar a capacidade de um grupo de 30 miRs humanos, muitos deles envolvidos em vias inflamatórias e na pluripotência, em modular aspectos relacionados a sobrevivência celular e EMT, em uma linhagem celular derivada de HNSCC (FADU) sob estímulo inflamatório. Inicialmente, avaliamos o potencial do TNF-? em modular parâmetros morfométricos, bem como a presença/localização de proteínas relacionadas com a EMT e capacidade migratória. Posteriormente, avaliamos o efeito de moléculas miméticas dos miRs em suprimir ou potencializar a sobrevivência celular e EMT em células estimuladas com TNF-?, seguido da identificação de transcritos alvos preditos (bem como das vias de sinalização enriquecidas para estes alvos) comumente alvejados por grupos de miRs que levaram a alterações multiparamétricas similares. De modo geral, miRs que alvejaram RELA e AKT2/AKT3 foram responsáveis pela redução na proliferação celular e EMT, enquanto o oposto foi observado em miRs que alvejaram GSK3B e ARHGAP5 (inibidor de RhoA). O silenciamento por siRNAs específicos contra RELA e CTNNB1, causou à redução na sobrevivência celular, enquanto que o silenciamento de AKT1 e CTNNB1 levou à redução na expressão proteica de SNAIL/SLUG. Finalmente, o silenciamento de RELA, AKT1, GSK3B e CTNNB1 levou a redução na sobrevivência celular e indução a apoptose mesmo na ausência de estimulação com TNF-?. Como um todo, nós demonstramos que a abordagem de HCS permitiu a identificação de miRs com efeitos fenotípicos similares (no contexto de proliferação e EMT) e que, a predição de alvos compartilhados por estes miRs, levou à identificação de alvos e vias de sinalização relevantes do ponto de vista terapêutico. / Like many solid cancers, in head and neck cancer (HNC) the presence of metastases is an important factor of poor prognosis. To date, studies indicate that, in the tumor inflammatory microenvironment, stimulation with Tumor Necrosis Factor Alpha (TNF-?) leads to the activation of different molecular pathways, such as the Nuclear Factor-Kappa B (NF-kB) and PI3K/AKT pathway, inhibiting GSK3? and the degradation of SNAIL and beta-catenin, stabilizing them promoting their nuclear translocation. In general, in several types of cancer, while beta-catenin acts to promote cell proliferation, members of the SNAIL family induce the epithelial-mesenchymal (EMT) transition process. It is known that EMT events are involved both in the initiation of metastases and generation of cancer stem cells (CSCs), which in turn are associated with therapeutic failure and relapse, due to its properties that confer resistance to conventional treatments. By silencing gene expression in a post-transcriptional fashion, microRNAs (miRs) have been associated with the regulation of both EMT and CSCs generation. Using the HighContent Screening (HCS) approach, we sought to investigate the ability of a group of 30 human miRs, many of them involved in inflammatory pathways and pluripotency, to modulate aspects related to cell survival and EMT, in a HNSCC-derived cell line (FADU) under inflammatory stimuli. Initially, we evaluated the potential of TNF-? in modulating morphometric parameters, as well as the presence/location of EMT-related proteins and migratory capacity. Subsequently, we evaluated the effect of miRs mimetic molecules on suppressing or potentiating cell survival and EMT in TNF-?-stimulated cells, followed by the identification of predicted target transcripts (as well as signaling pathways enriched for these targets) commonly targeted by groups of miRs that led to similar multiparametric changes. Overall, miRs that targeted RELA and AKT2/AKT3 were responsible for the reduction in cell proliferation and EMT, while the opposite was observed in miRs that targeted GSK3B and ARHGAP5 (RhoA inhibitor). Gene silencing by specific siRNAs against RELA and CTNNB1 caused a reduction in cell survival, while silencing of AKT1 and CTNNB1 led to reduced protein expression of SNAIL/SLUG. Finally, the silencing of RELA, AKT1, GSK3B and CTNNB1 led to a reduction in cell survival and induction of apoptosis even in the absence of TNF-? stimulation. As a whole, we demonstrated that the HCS approach allowed the identification of miRs with similar phenotypic effects (in the context of proliferation and EMT) and that the prediction of targets shared by these miRs led to the identification of relevant targets and signaling pathways from the therapeutic point of view.

Thesis (M. Phil.)--University of Hong Kong, 1999. / Includes bibliographical references (leaves 122-135).

<p>Minimally Invasive Robotic Surgery (MIRS) has revolutionized the way modern surgery is conducted by allowing for smaller incisions, finer control, reduced pain, and faster recovery. The state-of-the-art end-effector technology used for MIRS are tools based off of the rigid-body instruments used in traditional ‘open’ surgery. The rigid nature of the end-effectors, specifically the grasping jaws, leads to a lack of force feedback when implemented in a robotic system. </p> <p>Without additional feedback from active sensing, the blanching that occurs from restricted blood flow around a grasping site is the only indication a surgeon can use to assess the force applied to a tissue. Ongoing efforts to develop active force sensing solutions are currently faced with two major obstacles: miniaturization and sterilization. The lack of force feedback causes a gap between intention and result during robotic surgery. </p> <p>This work proposes the introduction of Visual Force Feedback (VFF) through the integration of a compliant end-effector design. Visual Force Feedback is an intuition, developed through practice, that allows a surgeon to estimate the reaction force of a compliant mechanism by the deflection of the outer flexures. An understanding of the relationship between opening size, flexure deformation, and pinch force allows for rapid estimation of the force applied to a manipulated object. </p> <p>Force and dimensional data were gathered through finite element simulation and the finite element model was validated with physical experimentation on a custom test bench. Multiple functions relating the flexure deformation to the reactionary force, referred to as pinch force, for specific opening sizes were resolved. Notable observations made through the analysis of these results were: (1) a closely linear relationship between outer flexure deformation and pinch force in both experimental and computational results and (2) a higher rate of pinch force increase due to draw displacement as an effect of wider jaw opening. These findings are intended to help shrink the gap between intention and result in the field of MIRS.</p>

No description available.

Thesis (M. Sc.)--University of Hong Kong, 1996. / Includes bibliographical references (leaf 87-94).

No description available.

In some organizations four generations work together creating a unique culture. Millennials are the second largest generation currently in the workforce. Organizational culture is affected by interpersonal communication. Interviews were conducted with 17 workers between the ages of 19 and 30. Interviews consisted of 22 open-ended questions regarding daily tasks, organized activities, and interpersonal interaction. The perspective of organizational culture was evaluated through personal, task, social, and organizational rituals. Membership categorization was used to determine common vocabulary used to identify with coworkers. Duck’s theory on attraction was used to evaluate interpersonal behavior seeking to determine psychological attractors acting as catalysts for relationship building. Data found suggests that Millennials create a culture similar to the tribal example suggested in previous research. Rituals act as forms of cultural dissemination and strengthening. The use of membership categorization devices reflected the structure of the organization and relationships between coworkers. Using Duck’s attraction theory, an analysis reflected the identification factors that act as catalysts for relationships. Psychological attraction was linked to common interests