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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
141

Nonhomologous end-joining: TDP1-mediated processing, ATM-mediated signaling

Hawkins, Amy 13 November 2009 (has links)
This thesis investigates two separate features of nonhomologous end-joining (NHEJ) DNA repair: end processing, and DNA repair kinase signaling. DNA end processing was investigated in a mouse model of hereditary spinocerebellar ataxia with axonal neuropathy (SCAN1), a congenital neurodegenerative disease. SCAN1 is caused by a homozygous H493R mutation in the active site of tyrosyl-DNA phosphodiesterase (TDP1). To address how the H493R mutation elicits the specific pathologies of SCAN1 and to further elucidate the role of TDP1 in processing DNA end modifications, we generated a Tdp1 knockout mouse and characterized their behavior and specific repair deficiencies in extracts of embryonic fibroblasts from these animals. While Tdp1(-/-) mice appear phenotypically normal, extracts from Tdp1(-/-) fibroblasts exhibited deficiencies in processing 3'-phosphotyrosyl single-strand breaks and 3'-phosphoglycolate (PG) double-strand breaks (DSBs). Supplementing Tdp1(-/-) extracts with H493R TDP1 partially restored processing of 3'-phosphotyrosyl single-strand breaks, but with evidence of persistent covalent adducts between TDP1 and DNA, consistent with a proposed intermediate-stabilization effect of the SCAN1 mutation. However, H493R TDP1 supplementation had no effect on PG termini on 3' overhangs of DSBs; these remained completely unprocessed. Altogether, these results suggest that for 3'-PG overhang lesions, the SCAN1 mutation confers loss of function, while for 3'-phosphotyrosyl lesions, the mutation uniquely stabilizes a reaction intermediate. Furthermore, there is evidence that TDP1 also localizes to mitochondria, and mitochondrial DNA damage should not be excluded from significantly contributing to SCAN1 pathology. The effect of ATM signaling on NHEJ was investigated via a novel vector that allows for inducing I-SceI-mediated DNA DSBs that can then be analyzed for NHEJ repair events by fluorescence- and PCR-based methods. Using highly specific DNA kinase inhibitors and the repair cassette, we showed that inhibiting ATM reduced NHEJ by 80% in a U87 glioma model. Analysis of the PCR products from the NHEJ repair vector by PsiI restriction cleavage allowed for assessment of the fidelity of the NHEJ repair: inhibiting ATM reduced high-fidelity NHEJ by 40%. Together, these results suggest that ATM is critical for NHEJ of I-SceI DSBs and for high-fidelity repair, possibly due to ATM's effects on chromatin architecture surrounding the DSB.
142

Posttranslační modifikace adaptorového proteinu DAXX v buněčné odpovědi na genotoxický stres / Posttranslational modification of the adapter protein DAXX in the cellular response to genotoxic stress

Bražina, Jan January 2016 (has links)
Maintaining the chromosome continuity and complete genetic information in human cells is crucial for cell survival and the whole organism. It prevents life-threatening pathologies and preserves genetic continuity. However, cellular DNA is exposed to both endogenous and exogenous stress damaging its content and integrity. This stress activates mechanisms involving detection and repair of these damaged sites (DDR). One of the most serious types of DNA damage double-stranded breaks (DSB) occuring when both strands are severed. DSBs trigger wave of PTMs that regulate protein interactions, nuclear localization and catalytic activity of hundreds of proteins. Such modifications include acetylation, methylation, SUMOylation, ubiquitinylation and especially phosphorylation. The most important kinases involved in DDR kinases are ATM, ATR and DNA-PK. These kinases are activated immediately after the detection of the damaged area. DAXX (Death-associated protein 6) is an adapter and predominantly nuclear protein, which is involved in chromatin remodeling, gene expression modulation, antiviral response and depositing histone H3.3 variants into chromatin or telomeres. Daxx is essential for murine embryogenesis, since the homozygous deletion is lethal in E9.5-10. In 2006 a study mapping the substrates of kinases...
143

Avaliação da cartilagem da ATM por meio de ressonância magnética com a utilização de bobinas microscópicas / MRI assessment of TMJs cartilage with the use of microscopic coils

Coutinho, Alessandra 02 October 2009 (has links)
Diferenças na espessura e regularidade da cartilagem da articulação temporomandibular (ATM) ocorrem como o resultado de áreas em crescimento ou em remodelamento. Esse aspecto dificulta a interpretação clínica das imagens e geralmente negligencia a presença da fibrocartilagem. O estudo, por meio da Ressonância Magnética utilizando bobinas microscópicas, possibilita uma melhor observação da cartilagem articular. Confirmamos essa evidência por meio do estudo que analisou 20 indivíduos (40 ATM), divididos em grupo sintomático (DTM) com 10 pacientes (20 ATM) apresentando queixa clínica e suspeita diagnóstica de DTM e, o grupo controle com 10 voluntários (20 ATM) assintomáticos ou que não apresentavam sinais e sintomas clínicos de DTM. As imagens de RM sagitais oblíquas ponderadas em DP SPIR da ATM foram capazes de mostrar a cartilagem com melhor evidência tanto na cabeça da mandíbula quanto na eminência articular proporcionado mensurações, as quais se apresentaram estatisticamente iguais entre os grupos e também a avaliação da regularidade com o mesmo comportamento entre os grupos e geralmente acompanhando a morfologia da cortical óssea. Em muitos casos, principalmente quando da presença de deslocamento para anterior do disco articular, a observação se torna mais difícil, requerendo mais prática para esse tipo de avaliação. Observamos que pacientes do grupo controle apresentaram deslocamento de disco. Dessa maneira, consideramos um exame muito útil como auxiliar no diagnóstico da DTM, e com o desenvolvimento de novas terapias para doenças degenerativas e traumas na cartilagem, as imagens de RM com o uso de bobina microscópica são de crescente importância clínica e poderão desempenhar um papel importante na avaliação da eficácia dessas terapias. / Differences in thickness and regularity of the temporomandibular joints (TMJ) cartilage occur as the result of areas of growth or remodeling. This fact leads to misinterpretations on diagnosis and generally neglects the presence of fibrocartilage. The present study, using MRI microscopic coils, allows better observation of the articular cartilage. This evidence was confirmed by this study that examined 20 individuals (40 TMJ), divided into: symptomatic group with temporomandibular dysfunction (TMD) of 10 patients (20 TMJ) presenting clinical complaint and TMD diagnosis; and the control group of 10 volunteers (20 TMJ) that were asymptomatic or who had no clinical signs and symptoms of TMD. On both groups were measured cartilage thickness and if the cartilage was regular or not. The oblique sagital MR images of weighted SPIR protons density (PD\'s) TMJ were able to show the best cartilage images either in the mandibles head or on the articular eminence providing measurements. Both groups presented no statistically significant differences regarding to thickness and the evaluation of the regularity presented the same result. The regularity of the cartilage generally was similar to the morphology of the cortical bone. In many cases, especially when the presence of anterior articular disc displacement, the evaluation was more difficult, requiring practice. The control group with asymptomatic patients was found also to have disc displacements. Thus, we review a very useful tool in the diagnosis of TMD and its importance to evaluate the cartilage to development new therapies for degenerative diseases and trauma. The MRI images with the use of microscopic coil are of increasing clinical importance and might play an important role in assessing the effectiveness of these therapies.
144

"Avaliação comparativa da anatomia do desenvolvimento da articulação temporomandibular, por meio do uso de ressonância magnética, reconstrução digital e cortes histológicos" / Comparative evaluation of the anatomical development of the temporomandibular joint, by means of magnetic resonance, digital econstruction and histological sections.

Nakazone Júnior, Sérgio 07 March 2005 (has links)
No presente estudo realizou-se a avaliação da eficácia do exame de imagem por ressonância magnética (IRM) e de reconstruções digitais bi e tridimensionais da ATM, em diferentes estágios de desenvolvimento. Foi criado um protocolo próprio de exame de IRM, o qual foi aplicado em embriões e fetos humanos, entre 22 a 160mm de comprimento céfalo-caudal (CRL), correspondendo da 7 a a 18 a semana de vida intra-uterina (IU). Em cada amostra foram realizadas duas seqüências de imagens sagitais da cabeça inteira, com distância de 1,0mm entre os cortes. Em seguida, as imagens foram intercaladas digitalmente, gerando uma seqüência de cortes de 0,5mm distância. Estas imagens foram importadas para um programa específico que realizou a reconstrução digital, criando modelos bi e tridimensionais. Para avaliar a formação e desenvolvimento das estruturas articulares de cada uma das amostras, foram realizados cortes histológicos da ATM. O exame histológico determinou o grau de maturação da ATM e a qualidade da matriz colágena presente. Os resultados demonstraram que o protocolo desenvolvido foi capaz de capturar e processar as imagens de IRM, principalmente após a 13 a semana de vida IU, em seu estágio de maturação articular. Os cortes histológicos comprovaram que, a partir desta fase, pode-se identificar melhor as estruturas articulares no exame de IRM devido a uma maior diferenciação celular e da matriz colágena, que passa de uma composição predominante de fibras colágenas tipo III para fibras do tipo I. A criação de modelos bi e tridimensionais mostrou ser uma ferramenta eficiente no diagnóstico do desenvolvimento facial, além de facilitar sua compreensão e aprendizado, embora ainda sejam necessários maiores avanços tecnológicos para a sua aplicação na formação das estruturas da ATM. / The present study was carried out to evaluate the effectiveness of Magnetic Resonance Imaging (MRI) and bi and three-dimensional digital reconstructions of the TMJ in different stages of development, by the comparison with histological sections. A proper protocol of IRM examination was developed, which was applied in formalin-preserved human embryos and fetuses, ranging from 22 to 160mm of crown-rump length (CRL), between 7 and 18 weeks of intrauterine life (IU). Two sequences of sagital images of the entire head of each specimen were performed, with interslice gap of 1,0mm. Consequently, images were digitally intercalated, creating a slice sequence of 0,5mm of interslice gap. These images were imported to the MRIcro Ò program for bi and three-dimensional digital reconstruction. In order to evaluate the development of the articular structures of each one of the specimens, histological sections of the TMJ were obtained. The maturation’s degree and the quality of the collagen matrix of the TMJ were determined by the histological sections . The results showed that the developed protocol was capable of capture and process MR images, mainly in the articular maturation stage, after the 13 th week of IU. Histological findings also showed that articular structures are better identified in this stage by RMI examination. This can be explained due to an increase of cellular and collagen matrix differentiation, which undergoes conversion from collagen type III to type I. Bi and three-dimensional models seem to be an efficient tool for the diagnosis of facial development, facilitating its understanding and learning. Further studies and technological advances may be necessary for its application in TMJ’s structures in intrauterine period.
145

Avaliação macroscópica e microscópica do cimento Portland comum - CP I e do cimento Portland branco não estrutural - CPB incluídos na calvária de ratos / Macroscopic and microscopic evaluation of Portland Cement Joint - CP I and the Portland Cement White not structural - CPB included in the skull of rats

Simões, Fabiano Geronasso 21 January 2009 (has links)
Os biomateriais podem ser definidos como substâncias de origem natural ou sintética que são tolerados de forma transitória ou permanente pelos diversos tecidos que constituem os órgãos dos seres vivos. Dentre esses biomateriais podemos citar o Agregado de Trióxido Mineral (ATM), que foi desenvolvido na Universidade de Loma Linda na década de 90. Desde então, não cessaram trabalhos de pesquisa envolvendo esse material e o Cimento Portland (CP); que embora não seja um material de uso odontológico direto, pode-se afirmar que possui basicamente os mesmos componentes químicos do ATM. O objetivo da presente pesquisa foi avaliar a biocompatibilidade do cimento Portland comum (CP-I) e do cimento Portland branco (CPB) não estrutural, incluídos na calvária de ratos. Foram selecionados vinte ratos, dois foram previamente utilizados como grupo piloto; os dezoito restantes foram distribuídos em três grupos de seis ratos que avaliados nos tempos experimentais de 30, 60, 90 dias foram mortos para análise histopatológica. Cada animal recebeu um implante, sendo três de Cimento Portland Comum (CP-I) e três de Cimento Portland Branco (CPB). Os resultados mostraram que não houve conseqüências de uma proliferação microbiológica em nenhum dos cimentos e tempos pesquisados. Observou-se tecido conjuntivo denso, celular e ricamente vascularizado. Também foi visualizado uma matriz óssea recém formada, adjacente aos osteoblastos ativos e que não estava ainda calcificada; apresentava-se menos mineralizada e com ausência de lamelas. Durantes os tempos histológicos de 30, 60 e 90 dias, o infiltrado inflamatório disperso no tecido apresentou-se: intenso, moderado e discreto. Sugerindo a mudança do processo inflamatório de agudo a crônico respectivamente / The biomaterials can be defined as substances of natural or synthetic origin that are tolerated on a temporary or permanent by the various tissues that make up the organs of living beings. Among these biomaterials can quote the mineral trioxide aggregate (MTA), which was developed at the University of Loma Linda, in the 90s. Since then, it stopped work on research involving this material and Portland cement (PC), which although not a dental material to use direct, one can say that basically has the same chemical components of the ATM. The purpose of this study was to evaluate the biocompatibility of common Portland cement (PC-I) and the white Portland cement (CPB) no structural, included in the skull of rats. Twenty rats were selected, two were previously used as a pilot group and the eighteen others were divided into three groups of six rats that were killed and evaluated in experimental stroke, 30, 60, and 90 days. Each animal received an implant, three of Common Portland Cement (PC-I) and three of White Portland Cement (CPB). The results show that there were no consequences of a microbial proliferation in any of cement and times searched. There was also the formation of bone tissue with characteristics of immaturity, showing gaps in some areas without osteocytes; presence of moderate and cell tissue, richly vascularized, showing characteristics of biocompatibility, and the potential for bone and cell differentiation.
146

As salas de auto-atendimento bancário, os caixas eletrônicos e suas interfaces gráficas: a usabilidade, funcionalidade e acessibilidade / The remote banking rooms, the ATM machines and its graphic interfaces: usability, function ability and accessibility

Salerno Junior, Edson 21 October 2008 (has links)
A pesquisa pretende estudar as interfaces gráficas, o desenho dos caixas eletrônicos e a arquitetura das salas de auto-atendimento das instituições bancárias mais representativas no cenário nacional, de acordo com seus índices de faturamento anual, desde a criação do Banco Central do Brasil na década de 1960 e os primeiros indícios de uma automação bancária, até o momento atual, sob a luz da funcionalidade, usabilidade e acessibilidade, dando início a uma abordagem crítica sobre o tema, investigando a partir de uma análise criteriosa, importantes aspectos do processo criativo, projetual e de implantação das interfaces gráficas, dos caixas eletrônicos e da arquitetura das salas de auto-atendimento. / This research intends to study the graphic interfaces, the design of the ATM machines and the remote banking rooms of the most representative bank institutions in the Brazilian scenario, according to their annual profits data, since the creation of the Central Bank of Brazil in the 1960\'s and the first appearances of the bank automation, until nowadays, focusing on the aspects of usability, function ability and accessibility, investigating important aspects of the creation, project and implantation processes of the graphic interfaces, the ATM machines and the remote banking rooms architecture.
147

Matching estável para tomada de decisão colaborativa na alocação de slots

Arruda Junior, Antonio Carlos de 29 April 2015 (has links)
Tese (doutorado)—Universidade de Brasília, Instituto de Ciências Exatas, Departamento de Ciência da Computação, 2015. / A tomada de decisão colaborativa (CDM) é um paradigma importante no processo de gerenciamento de tráfego aéreo (ATM). De acordo com a sua filosofia, a troca de informações entre os diversos intervenientes resultam em melhores decisões para o ATM. A construção dos algoritmos de alocação de slots utilizados nos programas de espera em solo (GDP) com CDM não contempla os principais stakeholders atuais no processo de tomada de decisão. Somando-se a esse fato, algumas deficiências no GDP têm sido relatadas em diversas pesquisas ao longo dos anos. Um desses problemas é que o algoritmo Compression nem sempre calcula resultados estáveis na alocação de recursos aeroportuários. Esta situação limita o desempenho do ATM e pode gerar insatisfação entre os stakeholders que são afetados. Para resolver os problemas citados, o presente trabalho propõe uma nova solução para o problema de alocação de slots tratado pelo algoritmo Compression. Esse modelo, denominado DA-SLOT, possibilita o tratamento dos stakeholders já existentes na CDM, bem como, a inclusão de um novo participante, o gestor do aeroporto. O modelo proposto utiliza a teoria de matching para criar um mercado de slots, onde as companhias aéreas e o gestor do aeroporto são jogadores que possuem preferências estratégicas no processo de alocação. O novo algoritmo utilizado nesse processo é baseado no mecanismo Deferred Acceptance (DA) para mercados de matching de dois lados. Os estudos de caso utilizados na validação do modelo empregaram movimentos aéreos do Aeroporto Internacional Tancredo Neves (SBCF) do ano de 2014, extraídos do site on-line da Empresa Brasileira de Infraestrutura Aeroportuária (INFRAERO). A análise realizada sobre cenários hipotéticos e reais indica que o modelo DA-SLOT permite adequado tratamento das preferências de todos os jogadores do mercado através de uma alocação ótima. Além disso, características desejáveis inerentes ao mecanismo DA, como estabilidade nas alocações e controle de manipulação dos resultados, podem levar os jogadores a buscarem resultados ótimos globais no sistema. Estes resultados podem ser considerados como as principais contribuições científicas e sociais da pesquisa. / Collaborative Decision Making (CDM) is an important paradigm in the process of Air Traffic Management (ATM). According to this paradigm, the exchange of information among the different entities result in the improved decisions for ATM. However, the construction of the slot allocation algorithms used in the Ground Delay Program (GDP) with CDM, does not address the current major stakeholders in the decision-making process. At the same time, some shortcomings in GDP have been reported in several studies over the last years. One of these problems is that the Compression algorithm in CDM not always calculates the stable results in the allocation of resources related to airport. These limits of the ATM performance can generate the dissatisfaction among the stakeholders. To solve these problems, this PhD thesis proposes a new solution for the slot allocation problem addressed in the Compression algorithm. This model, called DA-SLOT enables the treatment of existing stakeholders in the CDM, as well as the inclusion of a new participant, the airport management services. The proposed model uses the matching theory to create a market slots where the airlines and the airport managers are the players. These stakeholders in CDM have their strategic preferences in the allocation process. The new algorithm has been developed based on the Deferred Acceptance (DA) mechanism for two-sided matching markets. The case studies are conducted for evaluation the developed model with the real data from Tancredo Neves International Airport (SBCF) of 2014. All the scenarios and data have taken from the official website of the Brazilian Airport Infrastructure Company (INFRAERO). The analysis on hypothetical and actual scenarios indicates that DA-SLOT model allows the correct treatment of the preferences of all players in the market through a stable allocation. In addition, desirable characteristics inherited from the DA mechanism, such as stability in the allocation and control manipulation of the results, may lead stakeholders to get overall performances in the system. These results can be considered as the main scientificand social contributions of this research.
148

Role of Ataxia Telangiectasia Mutated Kinase in the Healing Process of the Heart Following Myocardial Infarction

Daniel, Laura L 01 May 2015 (has links)
Ataxia telangiectasia (AT), caused by mutations in the gene encoding ataxia telangiectasia mutated kinase (ATM), is a rare autosomal recessive disorder. AT individuals exhibit neuronal degeneration and are predisposed to cancer. Carriers of this disorder are predisposed to cancer and ischemic heart disease. Heart disease, mostly due to myocardial infarction (MI), is a leading cause of death in the US. Following MI, release of catecholamines in the heart stimulates β- adrenergic receptors (β-AR). Our lab has shown that β-AR stimulation increases ATM expression in the heart and myocytes, and ATM plays an important role in β-AR-stimulated myocardial remodeling with effects on function, fibrosis and apoptosis. Using wild-type (WT) and ATM heterozygous knockout (hKO) mice, this study investigated the role of ATM in the inflammatory, proliferative and maturation phases of infarct healing post-MI. During the inflammatory phase, 1 and 3 days post-MI, a deficiency of ATM resulted in decreased left ventricular dilation as measured by echocardiography. It decreased the number of neutrophils and macrophages in the heart 1 day post-MI. Myocardial fibrosis, expression of alpha-smooth muscle actin (α-sma) and apoptosis were higher in the infarct region of ATM deficient hearts. Akt activation (anti-apoptotic) was lower, while Bax expression (pro-apoptotic) was higher in the infarct region of ATM deficient hearts. During the proliferative phase, 7 days post-MI, ATM deficiency attenuated cardiac dysfunction as measured by echocardiography. ATM deficient hearts exhibited increased fibrosis and expression of α-sma in the infarct region with increased myocyte apoptosis in the border area. During the maturation phase, 14 and 28 days post-MI, ATM deficiency resulted in exaggerated cardiac function. It associated with increased fibrosis, expression of α-sma and decreased cardiac cell apoptosis in the infarct region 28 days post-MI. Myocyte hypertrophy was greater in the non-infarct region during ATM deficiency. ATM deficiency decreased expression of p16 (marker of cell senescence) and activation of proapoptotic protein, GSK-3β. Thus, ATM modulates the remodeling processes of the heart including function, fibrosis, apoptosis and hypertrophy post-MI. ATM (1) delays the inflammatory response post-MI, (2) decreases dilative remodeling during inflammatory and proliferative phases and (3) exaggerates dysfunction during the maturation phase.
149

Encaminhamento dinâmico em redes ATM

Marques, Rita Baptista January 2000 (has links)
Dissertação apresentada para obtenção do grau de Mestre em Engenharia Electrotécnica e de Computadores (Área de especialização de Telecomunicações), na Faculdade de Engenharia da Universidade do Porto, sob a orientação do Professor Doutor Raúl Teixeira Oliveira
150

Asynchronous transfer mode security

Shankaran, Rajan, University of Western Sydney, School of Computing and Information Technology January 1999 (has links)
There is a growing interest in the development of broadband services and networks for commercial use in both local area and wide area networks. The primary reasons for this is a pressing need to meet the demand for increased bandwidth for remote sites interconnection, and in high speed data transfer of bulk data such as images etc. There has also been a significant change in the characteristics of network traffic. It is increasingly taking the form of bursty traffic characterized by an unpredictable demand for bandwidth of several megabytes. A new generation of networking technologies have emerged to meet the demand of growing and uncertain bandwidth requirements. One such technology is called Asynchronous Transfer Mode (ATM) for use on broadband networks under the banner of broadband ISDN. ATM enables interconnection at high speeds in the range of Mbit/s or Gbit/s over wide areas, which effectively moves the bottleneck from networks to end systems. Furthermore, the user is able to access bandwidth on demand and the user is only charged for the bandwidth actually used. As more and more information (audio, image and data) is transferred over ATM networks, security issues are becoming increasingly critical. The rapidly growing use of the Internet to transfer confidential and sensitive information only enhances the importance of security services. One may even argue that the success of ATM will be determined not by its cost effectiveness but also to the level of trust that can be placed on its performance, security and availability. The objective of this dissertation is to address the issues involved in the design of security services for ATM networks. / Master of Science (Hons)

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