Dissertations / Theses: 'Elastin fibers'

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Grant, Tyler M. "Microstructural deformation of tendon." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:0ad70415-af7a-4b97-a93a-d17a73d8ff44.

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Tendon disorders are painful, disabling, and a major healthcare problem, with millions of people affected by tendon injuries each year. Current treatment strategies are inadequate and knowledge of the underlying mechanobiological mechanisms is required to develop novel therapies. Although the tissue–level properties of tendon are well–documented there remains a lack of understanding of the deformation mechanisms of this complex tissue. Therefore, the aim of this thesis is to characterize the microstructural deformation of tendon through biological imaging, mechanical testing, and computational modeling. Emphasis is placed on the structure and function of elastic fibers in tendon, whose role is poorly understood. First, histology, immunohistochemistry, and multiphoton microscopy are used to characterize the organization of elastic fibers in healthy and damaged tendon providing detailed microstructural information on their morphology and location for the first time. Elastic fibers are found to have a sparse distribution in the extracellular matrix, but are highly concentrated in the endotenon sheath and pericellular matrix. Moreover, damaged specimens are found to have a severely disrupted elastic fiber network. Elastic fibers likely contribute to fascicular deformation mechanisms and the micromechanical environment of tenocytes, which are expected to be disrupted in damaged tendon. Second, mechanical testing and enzyme treatments are used to analyze the mechanical contribution of elastic fibers to tendon. Elastase is found to significantly affect the mechanical properties of the tissue and remove the elastin component of both tendon and a control collagen–elastin biomaterial. However, elastase is also found to degrade non–elastin structural molecules that may contribute to tendon mechanics. The mechanical changes associated with the elastase treatment suggest that elastic fibers do not contribute to the elastic recoil of tendon as previously hypothesized. Third, multiphoton microscopy in combination with a novel microtensile testing machine is used to observe the deformation of collagen fibrils and tenocytes in tissue exposed to load. Tissue displacement is consistent with a helical arrangement of fibrils and nuclei experience significant elongation under physiological conditions. These results suggest that a helical arrangement of fibrils is responsible for the nonlinear stress–strain response of tendon and that nuclei are prime candidates for sensing mechanical forces in tendon. Finally, computation modeling and structural imaging are used to generate a microstructural finite element model of tendon. A helical model with embedded pericellular matrix is able to reproduce the stress–strain response and cell–level deformation of the tissue. The pericellular matrix is found to amplify mechanical forces exposed to cells, which is required to initiate mechanobiological stimulation of tenocytes under physiological conditions. Therefore, the structure and composition of the PCM during health and disease is expected to significantly affect mechanobiological mechanisms of tendon. The work presented in this thesis has used new experimental methods to provide novel insight into the structure, function, and deformation mechanisms of tendon. The techniques and concepts developed are widely applicable to the study of collagenous tissues in health and disease. In particular, observations regarding the pericellular matrix may lead to the development of new tissue–engineered and pharmacological strategies for the treatment of tendon disorders.

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Toroian, Damon Armen. "The Size exclusion characteristics of collagen and elastin fibers and role of fetuin in their calcification." Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2007. http://wwwlib.umi.com/cr/ucsd/fullcit?p3266770.

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Thesis (Ph. D.)--University of California, San Diego, 2007.
Title from first page of PDF file (viewed August 6, 2007). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.

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Ferron, Florence Joelle. "The implications of fibulin-5 on elastin assembly and its role in the elastic fiber /." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=101846.

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The extracellular matrix (ECM) is the material found surrounding the cells in a tissue. One component of the ECM is the elastic fiber, which confers the property of elasticity to its environment. Organs such as the lung, skin and major blood vessels have an abundance of elastic fibers so that they are able to expand and recoil. Elastic fibers are composed of two main components; elastin and microfibrils. Microfibrils are composed primarily of fibrillin-1 and provide a scaffold unto which tropoelastin monomers assemble. Elastic fibers interact with many other proteins in the ECM, one of which is fibulin-5. Based on the severe elastic fiber defects observed in the fibulin-5 null mouse, it was established that fibulin-5 plays an essential role in elastic fiber development. This role may be in the deposition of tropoelastin onto microfibrils and/or in stabilizing the elastic fibers in the extracellular matrix. In the present study, the relationship between fibulin-5 and the elastic fiber was investigated through a number of in vivo and in vitro experiments. To test the hypothesis that fibulin-5 requires the presence of elastin to assemble in the ECM, full-length recombinant fibulin-5 (rF5) was purified from transfected cells and used to make a fibulin-5 antibody. Solid-phase binding assays using rF5 showed that fibulin-5 binds tropoelastin at two sites; the initial portion of the C-terminus and the first calcium-binding epidermal growth factor-like domain at the N-terminus. Immunofluorescence staining of elastin null mouse embryonic fibroblast cultures revealed that fibulin-5 does not require elastin to be present in the ECM in order to assemble. Subsequently, solid-phase binding assays showed that fibulin-5 can bind to the N-terminus of fibrillin-1. To determine if fibulin-5 could exist independent of elastin and/or fibrillin-1 in vivo, an immunohistochemical analysis was conducted on heart, liver, lung, colon, spleen, testis and kidney. All three proteins were co-localized in all organs except in the kidney, where fibrillin-1 was found to independently stain the capillary tufts of the renal corpuscles and renal tubules. Thus, fibulin-5 may be co-regulated with elastin and is not present on elastin-independent microfibrils. Additionally, novel locations of elastic fibers were uncovered in the heart, liver, colon, spleen and testis. Overall, this study provides important insights as to the role of fibulin-5 in elastic fiber structure and assembly and also reveals the complexity in understanding the pathogenesis of diseases involving elastic fiber proteins.

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Smith, Kinley. "The distribution and function of elastin and elastic fibres in the canine cruciate ligament complex." Thesis, University of Liverpool, 2010. http://livrepository.liverpool.ac.uk/1437/.

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Anterior cruciate ligament rupture (ACL) is a major source of morbidity in the dog, leading to severe osteoarthritis of the knee joint and marked lameness. Following rupture, the ACL will not heal and in the dog, ACL rupture is thought to be the end stage of degenerative ligament disease (non-contact ACL injury). The extracellular matrix (ECM) of CLs has been extensively studied but little is known of the role of elastic fibres in the physiology of the ECM, the mechanics of CL function and in CL degeneration. Elastic fibres include polymers of fibrillins (microfibrils), bundles of microfibrils (oxytalan fibres) and elastin fibres (bundles of microfibrils with an elastin core). The hypothesis of this thesis is that elastin has a mechanical and a biological role in the canine cruciate ligament complex. It is further hypothesised that the distribution and function of elastic fibres will vary between three breeds of dog with differing risk of ACL rupture are: the greyhound with a low risk, the beagle with a low-to-moderate risk and the Labrador retriever with a high risk. The distribution of elastic fibres, fibrillins and cells was investigated throughout the CL complex using a combination of histochemical staining and immunofluorescence. CL microanatomy was studied using Nomarski differential interference microscopy. Elastin was measured biochemically and compared to histologic assessment of tissue architecture, elastic fibre staining and other biochemical parameters. The biological effect of elastin degradation products (EDPs) was assessed in an in vitro ACL cell culture model. A low risk dog breed to ACL rupture (greyhound) was used in all investigations and comparisons were made with other breeds with regard to cellular and elastic fibre anatomy. Differences in cell morphology between breeds with differing risk of ACL rupture may reflect fundamental differences in CL physiology possibly through altered cell-to-cell communication. Cellular and matrix changes, considered degenerative, were seen throughout the CL complex and may reflect adaptation rather than degeneration in certain dog breeds such as the greyhound. Elastin content ranged from 5.9 to 19.4% of ligament dry weight. This was a far greater proportion of canine CLs than previously. Elastin fibres may have a mechanical role in bundle reorganization following ligament deformation. The distribution of fibrillins 1 and 2 was different from the pattern previously reported in tendon and may represent a fundamental difference between ligament and tendon. In the greyhound CL there was a significant proportional increase in oxytalan fibre staining with advancing CL degeneration. This response was seen also in the Labrador retriever and the beagle but the increase in oxytalan fibre staining was less marked with advancing degeneration. Therefore production of oxytalan fibres may reflect a healing response in damaged CL tissue in breeds at a low risk of ligament rupture. Fragments of elastin containing the VGVAPG motif affect canine ACL cells in vitro resulting in increased transcription of fibrillin 2 mRNA. Additionally, there was synergism with TGF-β1 resulting in upregulation of the elastin laminin receptor 1, through which EDPs are transduced. EDPs may thus have a role in response to injury in the CL.

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Cholst, Beth (Beth Ellen). "Elastic stretchable optical fibers." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/105710.

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Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 23-24).
The utilization of soft materials in the design of optical systems provides opportunities for imparting these optical systems with completely unprecedented properties. This will enhance performance of systems, such as optical fibers, and enable new application scenarios. Here, we report the design, manufacture and characterization of elastic stretchable optical fibers. Analogous to conventional optical fibers, the elastic fibers consist of a high index core, made from a polystyrene-polyisoprene triblock copolymer, and a low refractive index cladding, formed by a fluorinated thermoplastic elastomer. The fibers are manufactured by co-extrusion of their constituent materials. They can be stretched to 300% strain repeatedly. Axial deformation of the fibers results in a variation of their light guiding properties. The fibers' attenuation coefficient was determined to be 0.021 ± 0.003 dB/mm, which is 2 orders of magnitude higher than for standard optical glass fibers. The high attenuation coefficient is likely due to scattering of light by air inclusions incorporated during manufacturing at the core-cladding interface. The fibers elastic modulus is 960 ± 280 kPA and their yield strength lies in the range of 2150 ± 480 kPA. The variation in intensity of guided light as a function of strain applied axially to the fibers was measured with a customized optical setup. Our experiments show that elastic optical fibers have properties that make them desirable as mechanical sensors and components in a range of other applications, provided current manufacturing shortcomings are addressed. The fibers could be used for light delivery to individual pixels of flexible deformable displays. They could be incorporated into clothing for delivery of light for display purposes or textile-integrated photonic circuits to create functional textiles. Because the fibers can stretch, the textiles or displays will be able to undergo deformation without damage or loss in performance.
by Beth Cholst.
S.B.

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Newcomb, Bradley Allen. "Gel spun PAN and PAN/CNT based carbon fibers: From viscoelastic solution to elastic fiber." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54881.

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This study focuses on the processing, structure, and properties of gel spun polyacrylonitrile (PAN) and polyacrylonitrile/carbon nanotube (PAN/CNT) carbon fibers. Gel spun PAN based carbon fibers are manufactured beginning with a study of PAN dissolution in an organic solvent (dimethylformamide, DMF). Homogeneity of the PAN/DMF solution is determined through dynamic shear rheology, and the slope of the Han Plot (log G’ vs log G’’). Solutions were then extruded into gel spun fibers using a 100 filament fiber spinning apparatus in a class 1000 cleanroom. Fibers were then subjected to fiber drawing, stabilization, and carbonization, to convert the PAN precursor fiber into carbon fiber. Carbon fiber tensile strength was shown to scale with the homogeneity of the PAN/DMF solution, as determined by the slope of the log G’ vs log G’’ plot. After the development of the understanding between the homogeneity of the PAN/DMF solutions on the gel spun PAN based carbon fiber tensile properties, the effect of altering the fiber spinning processing conditions on the gel spun PAN based carbon fiber structure and properties is pursued. Cross-sectional shape of the gel spun PAN precursor fiber, characterized with a stereomicroscope, was found to become more circular in cross-section as the gelation bath temperature was increased, the amount of solvent in the gelation bath was increased, and when the solvent was switched from DMF to dimethylacetamide (DMAc). Gel spun fibers were then subjected to fiber drawing, stabilization, and carbonization to manufacture the carbon fiber. Carbon fibers were characterized to determine single filament tensile properties and fiber structure using wide-angle x-ray diffraction (WAXD) and high resolution transmission electron microscopy (HRTEM). It was found that the carbon fiber tensile properties decreased as the carbon fiber circularity increased, as a result of the differences in microstructure of the carbon fiber that result from differences in fiber spinning conditions. In the second half of this study, the addition of CNT into the PAN precursor and carbon fiber is investigated. CNT addition occurs during the solution processing phase, prior to gel spinning. As a first study, Raman spectroscopy is employed to investigate the bundling behavior of the CNT after gel spinning and drawing of the PAN/CNT fibers. By monitoring the peak intensity of the (12,1) chirality in the as-received CNT powder, and in differently processed PAN/CNT fibers, the quality of CNT dispersion can be quickly monitored. PAN/CNT fibers were then subject to single filament straining, with Raman spectra collected as a function of PAN/CNT filament strain. As a result of the PAN/CNT strain, stress induced G’ Raman band shifts were observed in the CNT, indicating successful stress transfer from the surrounding PAN matrix to the dispersed CNT. Utilization of the shear lag theory allows for the calculation of the interfacial shear strength between the PAN and incorporated CNT, which is found to increase as the quality of CNT (higher aspect ratio, increased graphitic perfection, and reduced impurity content), quality of CNT dispersion, and fiber drawing increase. PAN/CNT fibers were then subjected to stabilization and carbonization for the manufacture of gel spun PAN/CNT based carbon fibers. These fibers were then characterized to investigate the effect of CNT incorporation on the structure and properties of the carbonized fibers. The gel spun PAN/CNT based carbon fibers were compared to commercially produced T300 (Toray) and IM7 (Hexcel) carbon fibers, and gel spun PAN based carbon fiber. Fiber structure was determined from WAXD and HRTEM. Carbon fibers properties investigated include tensile properties, and electrical and thermal conductivity. PAN/CNT based carbon fibers exhibited a 103% increase in room temperature thermal conductivity as compared to commercially available IM7, and a 24% increase in electrical conductivity as compared to IM7. These studies provide a further understanding of the processing, structure, property relationships in PAN and PAN/CNT based carbon fibers, beginning at the solution processing phase. Through the manufacture of more homogeneous PAN/DMF solutions and investigations of the fiber spinning process, gel spun PAN based carbon fibers with a tensile strength and modulus of 5.8 GPa and 375 GPa, respectively, were successfully manufactured in a continuous carbonization facility. Gel spun PAN/CNT based carbon fibers exhibit room temperature electrical and thermal conductivities as high as 74.2 kS/m and 33.5 W/m-K.

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Vieira, Gislaine. "Analise da arquitetura da aorta de pacientes hipertensos e normotensos." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/310241.

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Orientador: Konradin Metze
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas
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Resumo: Fibras elásticas são componentes essenciais da aorta e remodelamento é acompanhado em muitas doenças e eventos que ameaçam a vida, como dissecção e rupturas. Fibras elásticas podem ser facilmente visualizadas quando coradas com H&E e examinadas por microscopia de fluorescência. Nosso objetivo foi criar um sistema de análise automática da textura das fibras elásticas comparando aorta de pacientes normotensos e hipertensos. O sistema de análise foi composto por Microscópio invertido Olympus IX-81 equipado com scanner FV 300 que utiliza laser FV-5 COMB2, utilizando laser de argônio a 488 nm, objetiva 40x usando óleo de imersão. A espessura da aorta varia de 2 a 3 mm, e a imagem completa foi composta por justaposição de imagens de 220x220 µm utilizando software Fluoview. Para análise foi utilizado o programa gliding box , que é uma caixa deslizadora de 128x128 pixels, que percorre a imagem da aorta pixel a pixel em toda sua extensão. Para análise computadorizada da textura foram utilizados programas computacionais (entropia, homogeneidade local e segundo momento angular derivado da matriz de co-ocorrência de Haralick). Foram calculados e plotados em diagramas resultados equivalentes à topografia histológica da imagem. Em cada caminho o gliding box percorreu entre 2000 e 3000 pixels da textura, revelando a topografia local e sua variação. Foi comparada a textura de fibras elásticas de cortes histológicos corados com HE de 24 pacientes normotensos e 30 hipertensos, adultos de ambos os sexos oriundos de autópsias realizadas no Depto de Anatomia Patológica. Para comparação entre textura e idade utilizou-se Correlação de Pearson, e a textura foi comparada entre os grupos com o auxílio do teste t. Resultados: Tanto nos pacientes normotensos como nos hipertensos não houve correlação entre: número de fibras elásticas ou distâncias entre elas, para as análises de Haralick e idade dos pacientes. No entanto, a entropia em pacientes normotensos (r=0,60; p=0,004) e a homogeneidade local (r=0,43; p =0,049) demonstraram acréscimo da variação topográfica com o envelhecimento, fato que não ocorreu nos hipertensos. Quando comparadas com aortas normotensas, as hipertensas revelaram menos fibras elásticas (p<0,0001), maior variabilidade e distâncias (p<0,0001), aumento da média da espessura e maior variabilidade da espessuras das fibras ( p<0,0001). Conclusão: Demonstramos que o presente método é uma ferramenta que permite uma análise objetiva da textura de fibras elásticas da aorta com a possibilidade de quantificar processos patológicos. Observamos que em pacientes normotensos, o número médio de fibras elásticas e a distância entre elas são constantes e ocorrem discretas alterações da arquitetura com o aumento da idade. Em hipertensos, o distúrbio arquitetural é mais evidente e ocorrem perdas de fibras elásticas.
Abstract: The elastic fiber network is an essential component of the aorta. Its remodeling accompanies many diseases and may provoke life-threatening events, such as dissection or rupture. Elastic fibers can be easily demonstrated in eosin-stained histologic sections examined by fluorescence microscopy. The aim of our study was to create an automatic texture analysis system of the elastic fibers and to apply it in human aortas comparing normotensive and hypertensive patients. The analysis sytem was composed of an Olympus IX-81 inverted microscope, a FV300 scan head and a FV-5 COMB2 laser combiner. The fluorescence of the hematoxylin and eosin-stained slides was excited with the 488 nm line of an Argon laser using a 40x oil immersion objective. The Fluoview software was used to reconstruct the images. The full image of the whole sample (2 or 3mm long) was composed by several 220x220. Then a gliding box of 128x128 pixels was running in 1-pixel steps along a predefined axis parallel to the bottom line of the image. For every new box, computerized analysis of texture features (entropy, local homogeneity and the second angular moment derived from the gray-level co-occurrence matrix) were calculated and plotted in diagrams, where the position on the x-axis was equivalent to the topography in the histologic picture. In that way for each "run" of the gliding box about 2000 to 3000 values of a texture feature were obtained, thus revealing precisely its topographic postion and its variabilty. We compared the elastic fiber texture in routinely HE-stained histologic slides of the aorta ascendens in 24 normotensive and 30 hypertensive adult patients of both sexes and of similar age from our autopsy files. Pearson correlations were calculated between the texture features and the age. Texture features were compared between both groups with the help of the t-test. Results: In normotensive and hypertensive patients no correlations were found between the number of elastic fibers, their thickness or their distance and the Haralick features and the age of the patients. But in normotensive patients entropy (r=0,60; p=0,004) and local homogeneity (r=0,43; p =0,049) showed increasing topographic variations in patients with advanced age, which was not the case for hypertensive patients. When comparing with normotensive aortas, the hypertensive ones revealed less elastic fiber layers (p<0,0001), a greater variabilty of the fiber distance (p<0,0001), increased mean fiber thickness and a greater varaibilty of the fiber thickness( p<0,0001) Conclusion: We showed that the presented method provides a new tool for an objective automatic texture analysis of the elastic fiber texture of the aorta with the possibility of quantification of the disease process. Although in normotensive patients, the mean number and distance of the elastic fibers is constant, discrete local alterations of the architecture appear with increasing age. In hypertensive patients there are more pronounced architectural alterations with loss of the fiber layers.
Universidade Estadual de Campi
Biologia Estrutural, Celular, Molecular e do Desenvolvimento
Mestre em Fisiopatologia Médica

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Alves, Calebe de Andrade. "Dinâmica de degradação e reparação de fibras elásticas sob tensão." reponame:Repositório Institucional da UFC, 2013. http://www.repositorio.ufc.br/handle/riufc/13737.

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ALVES, Calebe de Andrade. Dinâmica de degradação e reparação de fibras elásticas sob tensão. 2013. 71 f. Dissertação (Mestrado em Física) - Programa de Pós-Graduação em Física, Departamento de Física, Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2013.
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Extracelular matrix, the biological structure that supports cells in animal tissue, is composed of elastic fibers such as collagen and elastin. It is known that enzymes activity plays an important role in maintenance of these elastic fibers. The imbalance between destruction and repair of the elastic fibers can lead to diseases such as fibrosis and emphysema. In this study, we present a simple model to simulate enzymatic digestion and repair of elastic fibers under tension. The fiber is represented by a chain of linearly elastic springs in series surrounded by two layers of sites along which particles representing enzymes and fragments can diffuse. These particles can biding-unbinding in the fiber simulating the reaction process by changing the local stiffness by a multiplicative factor. We study the distribution of the number of visits of particles to the springs as function of time and the consequent change of the fiber stiffness, under different initial conditions (model parameters). We show that, due to no linearity of the model, the degradation effect prevails even when the concentrations of the two type of agents are the same. There is no relation between the number of degradative and rigidifying particles that garantee that the fiber stiffness remains constant. When an anisotropy factor is included on the model and the system behaviour becomes dependent on the tension applied to the fiber, we show that the increase of tension in general contributes to the increase on enzymatic activity. We believe this study can help better understand progression of diseases such as emphysema and fibrosis.
A Matriz Extracelular, a estrutura biológica que sustenta as células em tecidos animais, é composta de fibras elásticas como colágeno e elastina. Sabe-se que a atividade enzimática desempenha papel fundamental na manutenção dessas fibras elásticas. O desequilíbrio entre destruição e reparo das fibras elásticas pode levar a doenças como fibrose e enfizema. Neste estudo, nós apresentamos um modelo simples para simular digestão enzimática e reparo de fibras sob tensão. A fibra é representada por uma cadeia de molas linearmente elásticas em série. A fibra é cercada por duas camadas de sítios ao longo dos quais partículas representantes de enzimas e fragmentos podem se difundir. Estas partículas podem se ligar e se desligar da fibra, simulando o processo de reação ao alterar a constante elástica local por um fator multiplicativo. Estuda-se a distribuição do número de visitas de partículas degradadoras e enrijecedoras às molas em função do tempo de difusão e a consequente variação da rigidez da fibra, sob diversas condições iniciais (parâmetros do modelo). Mostra-se que, devido a características matemáticas intrínsecas ao modelo, o efeito de degradação prevalece sobre o de enrijecimento ainda quando a concentração de agentes de ambos os tipos é a mesma. Não há relação entre o número de partículas degradadoras e enrijecedoras que garanta a estabilidade da constante elástica da fibra. Quanto um fator de anisotropia é incluído no modelo e o comportamento do sistema passa a depender da tensão aplicada à fibra, mostra-se que o aumento da tensão em geral contribui para o aumento da atividade enzimática. Este estudo poderá ajudar a entender a progressão da degradação de tecidos em doenças como enfisema e fibrose.

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Lima, Vanessa Morais. "Efeitos da penicilina G na pelve renal de ratos Wistar (Rattus norvegicus albinus) normais e diabéticos." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/10/10132/tde-09102013-180434/.

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A penicilina G é um dos antibióticos mais importantes. Além de possuir um baixo preço e comprovada eficácia de tratamento, mostra inúmeras possibilidades para a redução da morbidade e mortalidade por doenças infecciosas em todo o mundo. Como eventualmente este medicamento causa sequelas no parênquima renal e estruturas associadas, e sendo que a secreção da rede tubular renal contribui para a excreção da penicilina G, onde cerca de 60% do antibiótico é eliminado pela urina, nos propomos a fazer um estudo das principais alterações que possam ocorrer na pelve renal de ratos normais e ratos induzidos à diabetes. Este projeto tem o propósito de descrever e analisar as fibras colágenas, musculares lisas e elásticas da pelve renal de ratos wistar observando alterações estruturais e ultraestruturais dos grupos experimentais quando comparados ao grupo controle com relação ao uso da penicilina G. Os ratos foram divididos em 4 grupos, ratos Wistar normais (N); ratos Wistar tratados com penicilina G (NP); ratos Wistar induzidos à diabetes (D); ratos Wistar diabéticos com penicilina G (DP). Os ratos dos grupos D e DP foram induzidos ao diabetes por aloxano. A região da pelve renal com representação das fibras foi coletada e reduzida em pequenos fragmentos. Os cortes obtidos foram utilizados para Microscopia Eletrônica de Transmissão e corados pelos seguintes métodos para Microscopia Óptica: Hematoxilina Férrica para evidenciação de fibras elásticas; Resorcina fucsina para evidenciação de fibras elásticas e elaunínicas; Resorcina fucsina após oxidação com solução aquosa a 1% de oxona para evidenciação de fibras elásticas, elaunínicas e oxitalânicas; Azan para evidenciação do componente colágeno e muscular lisa; Picrosírius para observação do componente colágeno (especificamente tipo I e III); e Hematoxilina e Eosina, para evidenciação do componente celular. A análise microscópica e a histomorfometria mostraram que a Penicilina G altera os componentes fibrosos da pelve renal, fazendo com que as áreas de fibras musculares lisas e de colágeno tipo III fossem aumentadas e as fibras elásticas maduras diminuídas (neste caso, apenas entre N e NP). O Diabetes mellitus mostrou-se como uma doença metabólica também capaz de alterar a morfologia da pelve, fazendo com que a área de fibras musculares lisas aumentasse, a área de colágeno tipo I e a quantidade de fibras elásticas maduras e elaunínicas diminuísse e as oxitalânicas aumentassem, além de um notável aumento na quantidade de mitocôndrias. Podemos inferir que a antibioticoterapia feita pela penicilina G e o diabetes, provocam diferenças estruturais e ultraestruturais na pelve renal dos ratos Wistar, principalmente na organização dos componentes fibrosos elástico, muscular e colágeno.
Penicillin G is the most important antibiotics. Besides having a low cost and proven effectiveness of treatment, it shows great possibilities for reducing morbidity and mortality from infectious diseases worldwide. As this medicine may cause sequelae in the renal parenchyma and associated structures, and since the net renal tubular secretion contributes to the excretion of penicillin G, where about 60% of the antibiotic is eliminated in urine, this study aims to investigate the main structural and ultrastructural changes occurring in the kidney of normal and diabetes rats. Thus, this project aims to describe and analyze the collagen fibers, smooth muscle and elastic fibers of the renal pelvis of Wistar rats, comparing control and penicillin G-treated animals. The animals were divided into 4 groups, normal rats (N), Wistar rats treated with penicillin G (NP); rats induced diabetes (D), diabetic Wistar rats with penicillin G (DP). The diabetes was induced in groups D and DP by alloxan. The fibrotic region of the renal pelvis was collected and reduced into small fragments. The sections were used for the transmission electron microscopy and stained by the following methods for optic microscopic: Iron Hematoxylin for disclosure of elastic fibers; Resorcin fuchsin for disclosure of elastic and elauninic fibers; Resorcin fuchsin after oxidation with 1% aqueous solution of oxone for disclosure of elastic, elauninic and oxytalan fibers; Azan evidencing the collagen and smooth muscle components; Picrosirius for observation of the collagen component (specifically type I and III); and Hematoxylin and Eosin, to show the cellular component. Microscopic and histomorphometry analysis showed that penicillin G alters the fibrous components of the renal pelvis, increasing areas of smooth muscle fibers and collagen type III deposition and decreasing mature elastic fibers (in this case, only between N and NP). Diabetes mellitus proved to be a metabolic disease also able to alter the morphology of the pelvis, leading to the augmentation of smooth muscle fiber area. Moreover, the area of type I collagen and the amount of mature elastic and elauninic fibers were diminished, while oxytalan fibers increased, together with a remarkable increase in the number of mitochondria. We can infer that the antibiotic therapy made by penicillin G and the diabetes, cause structural and ultrastructural differences in the renal pelvis of rats, mainly in the organization of elastic fiber, muscular and collagen components.

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Rosado, João Pedro Gaio Meireles. "Alterações estruturais da matriz extracelular do prepúcio humano causadas pelo tabagismo." Universidade do Estado do Rio de Janeiro, 2011. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=3859.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico
Os autores têm como objetivo, investigar a matriz extra celular, musculatura lisa e densidade vascular do prepúcio de pacientes tabagistas. Espécimes de prepúcio foram obtidas de 20 jovens adultos (média de idade= 27.2) submetidos a postectomia. Dentre os pacientes analisados, um grupo (n=10) possui história prévia de tabagismo (3 to 13 maços/ano, média = 5.8 3.2), e outro grupo (n=10) formam o grupo controle, não fumantes. A coloração de Tricrômico Masson foi utilizada para quantificar tecido conectivo, musculatura lisa e vasos. A coloração Resorcina-fucsina de Weigert foi utilizada para estabelecer as fibras do sistema elástico e a coloração, Vermelho de Picrosirius para o estudo do colágeno. O estudo estereológico foi realizado utilizando o software Image J, para determinar as densidades volumétricas. Para a análise bioquímica o colágeno total foi determinado em μg de hidroxiprolina por MG de tecido seco. O estudo estatístico foi realizado lançando mão do t-teste (p<0,05). Fibras do sistema elástico de fumantes apresentaram-se aumentadas em 42.5% quando comparado ao grupo controle (p=0,002). Em contraste, musculatura lisa (p=0,42) e densidade vascular (p=0,16) não mostraram nenhuma diferença estatística. Foi realizado uma análise quantitativa utilizando Vermelho de Picrosirius sob luz polarizada, que evidenciou a presença de colágeno tipo I e III, sem diferença estatisticamente significativa. A concentração total do colágeno não mostrou diferença entre tabagistas e o grupo controle. (73.1μg/mg 8.0 vs. 69.2μg/mg 5.9, respectivamente, p=0,23). Tabagismo está associado a um significante aumento de fibras do sistema elástico do tecido prepucial. Estes resultados podem, possivelmente, explicar os altos índices de falha na uretroplastia peniana, com uso de flap de prepúcio em fumantes
It has been speculated by McAninch et al. (1), that smokers might experience worse results after urethral reconstruction. We decided to investigate the extracellular matrix, smooth muscle and vascular density in the foreskin of smoker patients. Foreskin samples were obtained from 20 young adults (ranging in age from 23 to 36 years; mean SD = 27.2 5.8) submitted to circumcision from July 2008 to October 2009. Of the patients analyzed, one group (n=10) had a previous history of chronic smoking (3 to 13 packs/year, mean = 5.8 3.2) i.e., one pack per day for 3 to 13 years. The control group was composed of 10 non-smoker patients. Foreskin samples were studied by histology and biochemistry. Means were compared using the two-tailed t-test (p<0.05). The elastic system fibers in the foreskin of smoker patients increased in 42.5% when compared to the control group. In contrast, the smooth muscle fibers, vascular density and total collagen concentration did not show any significant variation between smokers and controls. Smoking is associated with a significant increase of elastic system fibers in foreskin tissue. These results could possibly explain the high failure rate of penile urethroplasty in smokers by using foreskin flaps

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Herreros, Fernanda Oliveira Camargo. "Remodelamento da derme humana apos aplicação de salicilato de silanol." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/311629.

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Orientador: Paulo Eduardo Neves Ferreira Velho
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas
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Resumo: A intradermoterapia é um processo terapêutico com poucas publicações científicas em revistas indexadas. Em 2005, um estudo duplo-cego randomizado demonstrou os benefícios proporcionados para a pele, cabelos e unhas de mulheres com fotoenvelhecimento pelo consumo de um suplemento oral de silanol. Frente a esses dados, realizou-se um estudo com o objetivo de comparar as alterações histológicas entre a pele humana que recebeu injeção intradérmica de silanol e as encontradas na pele em que foi injetado soro fisiológico. Dez mulheres caucasianas, sadias, com grau moderado de fotoenvelhecimento, voluntariamente receberam dez sessões semanais de injeções com salicilato de silanol 0,1% no antebraço esquerdo, e injeções de soro fisiológico no antebraço direito. No momento da biópsia, duas semanas depois, três pacientes recusaram-se a realizar o procedimento. Os achados histológicos nas áreas injetadas com silanol e com soro fisiológico, encontrados em biópsias, foram avaliados e comparados por um pesquisador de forma cega e as fibras colágenas e elásticas de cada lado foram quantificadas. A análise da textura da derme foi feita a partir das imagens microscópicas digitalizadas, por meio da dimensão fractal de Sarkar e do cálculo das amplitudes (valores de inércia), após a transformada rápida de Fourier. A área injetada com silanol revelou um aumento estatisticamente significativo da densidade de fibras colágenas e elásticas. A análise de textura revelou uma distribuição mais compacta e mais homogênea das fibras de colágeno. O resultado desse estudo sugere que a aplicação de um silício orgânico pode estimular a síntese das fibras elásticas e colágenas, levando a um remodelamento da estrutura da derme, o que pode explicar a melhora da aparência da pele, observada em estudos clínicos. Com base nestes resultados, relatou-se o caso de uma paciente com cicatrizes atróficas resultantes de micobacteriose atípica tratada com doxiciclina por seis meses. A paciente havia se submetido à hidrolipoclasia por ultra-som e a infecção desenvolveu-se nos locais do procedimento. Esta complicação ainda não havia sido descrita na literatura médica associada a tal procedimento. As cicatrizes foram submetidas a cinco sessões de intradermoterapia com salicilato de silanol, apresentando melhora parcial da aparência
Abstract: Mesotherapy is a technique that lacks scientifical clinical trials. In 2005, a controlled double-blind study in patients with photo-aged facial skin demonstrated the beneficial role of oral intake of silanol for skin, hair and nails. Facing it, a study was developed to compare histological alterations in human skin that received intradermal injections of silanol. Ten healthy female caucasian volunteers with a moderate degree of photoaged skin received ten sessions of weekly injections of 0.1% salicylate silanol in the left ventral lateral forearm and physiological solution injections on the right forearm. At biopsy time, three patients denied to receive this procedure. The histological features of punch biopsies of the treated area and the nontreated contralateral arm were compared and the collagen and elastic fibers were quantified by a blind physician. Texture analysis was performed on digitalized microscopic images by analyzing the Sarkar fractal dimension and amplitudes (inertia values) after Fast Fourier transformation. The treated area revealed a statistically significant increase of the density of both collagen and elastic fibers. Texture analysis showed more compact and homogenously distributed collagen fibers after silicon injection. This result suggests that the application of silicon may stimulate the production of collagen and elastic fibers leading to remodeling of the dermal fiber architecture, which may explain the improvement of the skin surface observed in clinical studies. Also, a case report illustrates a mycobacteria infection following an ultrasound hydrolipoclasia procedure, complication not previously reported in medical literature. After the antibiotic treatment, the patient developed atrophic scars, that received five sessions of mesotherapy with silanol, with some improvement in scar appearance
Doutorado
Clinica Medica
Doutor em Clínica Médica

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Rocha, Vinícius Novaes. "Estudo dos efeitos da hipertensão arterial nas alterações morfológicas da valva atrioventricular esquerda (mitral) de ratos hipertensos induzidas por L-NAME." Universidade do Estado do Rio de Janeiro, 2009. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=4653.

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As valvas cardíacas têm como função manter o fluxo unidirecional do sangue e para isso conta com uma arquitetura anisotrópica da matriz extracelular que assegura e sustenta uma adequada função sob condições de alta e baixa pressão. A valvopatia é uma desordem que pode acometer qualquer uma das valvas cardíacas por qualquer modificação em sua estrutura que impossibilita o seu adequado funcionamento. Estudos demonstram que o stress mecânico ocasionado pelo fluxo sanguíneo pode interferir na estrutura organizacional das células e matriz extracelular da valva. O presente estudo teve como objetivo investigar as possíveis alterações estruturais e ultraestruturais que a hipertensão arterial, induzida por L-NAME, pode ocasionar na valva atrioventricular esquerda (mitral) de corações de ratos. Os animais receberam L-NAME (40mg/kg/dia), previamente diluído na água de beber, durante um período de cinco semanas. Ao final da quinta semana foi realizada a eutanásia dos animais e fragmentos da válvula parietal foram coletados e processados para microscopia de luz e eletrônica. Foram analisadas as estruturas morfológicas das válvulas tanto para microscopia óptica (histoquímica) quanto microscopia eletrônica (histoquímica ultraestrutural e imunohistoquímica ultraestrutural), assim como, a espessura da válvula e a quantificação (%/area) das fibras elásticas e colágenas através do programa ImagePro-Plus 4.5. Os animais tratados com L-NAME desenvolveram hipertensão a partir da segunda semana de administração do fármaco. Estruturalmente foi possível identificar uma desorganização das fibras elásticas e colágenas com regiões de fragmentação. Os animais hipertensos apresentaram regiões da válvula mais espessas do que o controle, além de uma menor porcentagem de fibras colágenas. Ultraestruturalmente, identificamos modificações do endotélio nos animais tratados com L-NAME, que se apresentou com contorno irregular e com acúmulos de vesículas no seu interior. Além disso, foi observada também fragmentação da lâmina basal, desorientação das fibras colágenas, acúmulo de fibras oxitalânicas próximo ao endotélio e fragmentação das fibras elástica da região atrial. O presente trabalho concluiu que o aumento da pressão sanguínea, caracterizada pela hipertensão, ocasiona modificações na estrutura morfológica da válvula, que pode estar associado de forma sinérgica com a inibição da síntese óxido do nítrico, podendo assim, prejudicar o seu perfeito funcionamento.
The heart valves are designed to maintain the unidirectional blood flow and for this reason they have an anisotropic architecture of the extracellular matrix that ensures and maintains proper function under conditions of high and low pressure. The valve disease is a disorder that can affect any of the heart valves, marked by any change in its structure that prevents its proper operation. Studies show that the mechanical stress caused by blood flow may interfere with the organizational structure of cells and extracellular matrix of the valve. This study aimed to investigate the possible structural and ultrastructural changes that hypertension, induced by L-NAME, can cause to the left atrioventricular valve (mitral) from hearts of rats. The animals received L-NAME (40mg/kg/dia), previously diluted in water, for five weeks. At the end of the fifth week euthanasia of animals was performed and the valve parietal fragments were collected and processed for light microscopy (histochemistry) and electron microscopy (ultrastructural histochemistry and ultrastructural immunohistochemistry). It was analyzed the morphological structure of the valves at both structural (light microscopy) and ultrastructural (electron microscopy), as well as the thickness of the valve and quantification (% / area) of the elastic and collagen fibers through the ImagePro-Plus 4.5. The animals treated with L-NAME developed hypertension from the second week of administration of the drug. Structurally, it was possible to identify a disorganization of the elastic and collagen fibers with regions of fragmentation. The hypertension animals showed thicker valve regions than control, plus a smaller amount of collagen fibers. Ultrastructurally, it was identified changes of the endothelium in animals treated with L-NAME, where it presented irregular contours and accumulations of vesicles inside. Furthermore, it was also observed fragmentation of basal lamina, disorientation of collagen fibers, fiber oxytalan accumulation near the endothelium and fragmentation of elastic fibers of the atrial layer. This study concluded that increased blood pressure, characterized by hypertension, causes changes in the morphological structure of the valve, which may be linked in with the synergistic inhibition of nitric oxide synthesis, and may thus undermine its perfect operation.

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Patricio, Licia Mioko Yoshizaki Akinaga. "Efeitos da poluição atmosférica de origem veicular no sistema cardiopulmonar de camundongos Swiss (Mus musculus L.) recém-natos expostos até a idade adulta." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/5/5160/tde-16122008-102039/.

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INTRODUÇÃO: A exposição contínua desde o nascimento à poluição atmosférica de grandes centros urbanos de origem predominante veicular, contribui para eventos cardiopulmonares em adultos. A inflamação e remodelamento induzidos pelos poluentes podem modular a resposta vascular a mediadores e alterar a sua patência e reatividade contribuindo para eventos isquêmicos. MÉTODOS: Verificar alterações inflamatórias e estruturais nos pulmões e corações de camundongos Swiss machos cronicamente expostos, desde o nascimento até a idade adulta, às câmaras seletivas com filtros (câmara limpa) e sem filtros (câmara poluída) para particulados e gases tóxicos, situadas a 20m de um cruzamento de tráfego intenso da cidade de São Paulo, 24 h/7dias/semana/4 meses. Realizaram-se medidas internas e externas dos poluentes: PM2,5; NO2 e Black Carbon (BC) e análises morfométricas nos pulmões e corações. RESULTADOS: A filtragem da câmara limpa clareou 100% de BC, 52% de PM2,5 e 32% de NO2. Nos pulmões, as alterações predominaram na região peribronquiolar. Os animais submetidos à câmara poluída apresentaram inflamação peribronquiolar caracterizada por aumento do infiltrado perivascular (p=0,022), hiperplasia do epitélio bronquiolar (p=0,037), escore inflamatório total (p=0,015), e diminuição do infiltrado polimorfonuclear na região do septo alveolar distal (p=0.001). A parede dos vasos peribronquiolares não demonstrou alteração da razão lúmen/parede (L/P) entre os grupos (0,094), porém, os animais submetidos à câmara poluída, apresentaram remodelamento estrutural com diminuição de fibras elásticas na adventícia (p= 0,006) e na túnica média (p= 0,008) e das fibras colágenas apenas na adventícia (p= 0,016). No miocárdio, verificamos aumento do número de núcleos por área do VE, sem alteração de peso dos corações entre os grupos (p=0,005). As coronárias dos camundongos expostos à câmara poluída também não demonstraram diferenças na razão L/P, porém a poluição induziu remodelamento através de aumento de fibras colágenas e elásticas na camada adventícia e média dos vasos (p<0.001; p=0,03 respectivamente), mesmo quando categorizados os vasos por seu calibre e por ventrículo separadamente (p<0,001). CONCLUSÃO: A poluição atmosférica da cidade de São Paulo, Brasil, induziu alterações inflamatórias e estruturais nos pulmões e corações dos animais normais expostos desde o nascimento até a idade adulta. A resposta pulmonar caracterizou-se por inflamação e diminuição das fibras da matriz extracelular dos vasos, enquanto as coronárias apresentaram fibrose e elastogênese em toda parede vascular. Esses achados reforçam a hipótese de que a poluição atmosférica de grandes centros urbanos induz alterações silenciosas porém significativas, órgão-específicas, modulando a resposta vascular, podendo contribuir para alteração da patência e reatividade dos vasos e eventos isquêmicos na idade adulta
INTRODUCTION: The continuous exposition since birth to atmospheric pollution of great urban centers originated by vehicles predominantly, contributes to cardiopulmonary events in adults. The remodeling and inflammation induced by airborne pollutants may modulate the vascular response to mediators and alter the vascular patency and reactivity which may contribute to ischemic events. METHODS: To verify the inflammatory and structural alterations of the lungs and heart of Swiss male mice chronically and continuously exposed since birth to adulthood, to selective chambers with (clean) or without (polluted) filter devices for particles and toxic gases, 7days/24h/4 months, located 20m far from a cross-road with heavy traffic in Sao Paulo city downtown. Measurements of PM2,5; NO2 and Black Carbon (BC) inside the chambers and in the external environment and morphometric analyses of the lung and heart were made. RESULTS: Filters cleared 100% of BC, 47% of PM2,5 and 68% of NO2 in the clean chamber. In the lungs, pollutants affected predominantly the peribronchiolar area. Animals submitted to the polluted chamber presented peribronchiolar inflammation characterized by increased perivascular influx (p=0.022), bronchiolar epithelial hyperplasia (p=0.037), total inflammatory scores (p=0.015), and decrement of polymorphonuclear cells infiltration in the distal septa (p=0.001). There was no difference of the lumen/wall ratio (L/W) of peribronchiolar vessels (p=0.094) between groups. However, mice from polluted chamber presented structural remodeling characterized by decrement of elastic fibers in both adventitia (p=0.006) and media layers (p= 0.008) and collagen content in the adventitia (p= 0.016). In the heart, there was an increase of nucleus of myocytes/left ventricle area, but no alteration of the myocardial weight between groups (p=0.005). Although the coronary arterioles from mice exposed to polluted ambient did not show differences of L/W ratio when compared to those from clean ambient, pollutants induced increment of collagen and elastic fibers in the adventitia and media vascular layer (p<0.001; p=0.03 respectively), even when vessels were categorized by caliber and per ventricle chamber separately (p<0.001). CONCLUSION: The continuous exposure to atmospheric pollution of São Paulo city, Brazil, since birth to adulthood, induced inflammatory and structural alterations in the lungs and heart. The lung response was characterized by inflammation and decrement of extracellular matrix fibers while in the heart, there was fibrosis and elastin increment in the coronary arteriolar wall. These results reinforce the hypothesis that urban airborne pollution predominantly generated by traffic, induces silent but significant organ-specific alterations, which may impair vascular patency and reactivity and may contribute to ischemic cardiac events in the adulthood

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Alves, Calebe de Andrade. "DinÃmica de degradaÃÃo e reparaÃÃo de fibras elÃsticas sob tensÃo." Universidade Federal do CearÃ, 2013. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=9511.

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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico
A Matriz Extracelular, a estrutura biolÃgica que sustenta as cÃlulas em tecidos animais, Ã composta de fibras elÃsticas como colÃgeno e elastina. Sabe-se que a atividade enzimÃtica desempenha papel fundamental na manutenÃÃo dessas fibras elÃsticas. O desequilÃbrio entre destruiÃÃo e reparo das fibras elÃsticas pode levar a doenÃas como fibrose e enfizema. Neste estudo, nÃs apresentamos um modelo simples para simular digestÃo enzimÃtica e reparo de fibras sob tensÃo. A fibra Ã representada por uma cadeia de molas linearmente elÃsticas em sÃrie. A fibra Ã cercada por duas camadas de sÃtios ao longo dos quais partÃculas representantes de enzimas e fragmentos podem se difundir. Estas partÃculas podem se ligar e se desligar da fibra, simulando o processo de reaÃÃo ao alterar a constante elÃstica local por um fator multiplicativo. Estuda-se a distribuiÃÃo do nÃmero de visitas de partÃculas degradadoras e enrijecedoras Ãs molas em funÃÃo do tempo de difusÃo e a consequente variaÃÃo da rigidez da fibra, sob diversas condiÃÃes iniciais (parÃmetros do modelo). Mostra-se que, devido a caracterÃsticas matemÃticas intrÃnsecas ao modelo, o efeito de degradaÃÃo prevalece sobre o de enrijecimento ainda quando a concentraÃÃo de agentes de ambos os tipos Ã a mesma. NÃo hÃ relaÃÃo entre o nÃmero de partÃculas degradadoras e enrijecedoras que garanta a estabilidade da constante elÃstica da fibra. Quanto um fator de anisotropia Ã incluÃdo no modelo e o comportamento do sistema passa a depender da tensÃo aplicada Ã fibra, mostra-se que o aumento da tensÃo em geral contribui para o aumento da atividade enzimÃtica. Este estudo poderÃ ajudar a entender a progressÃo da degradaÃÃo de tecidos em doenÃas como enfisema e fibrose.
Extracelular matrix, the biological structure that supports cells in animal tissue, is composed of elastic fibers such as collagen and elastin. It is known that enzymes activity plays an important role in maintenance of these elastic fibers. The imbalance between destruction and repair of the elastic fibers can lead to diseases such as fibrosis and emphysema. In this study, we present a simple model to simulate enzymatic digestion and repair of elastic fibers under tension. The fiber is represented by a chain of linearly elastic springs in series surrounded by two layers of sites along which particles representing enzymes and fragments can diffuse. These particles can biding-unbinding in the fiber simulating the reaction process by changing the local stiffness by a multiplicative factor. We study the distribution of the number of visits of particles to the springs as function of time and the consequent change of the fiber stiffness, under different initial conditions (model parameters). We show that, due to no linearity of the model, the degradation effect prevails even when the concentrations of the two type of agents are the same. There is no relation between the number of degradative and rigidifying particles that garantee that the fiber stiffness remains constant. When an anisotropy factor is included on the model and the system behaviour becomes dependent on the tension applied to the fiber, we show that the increase of tension in general contributes to the increase on enzymatic activity. We believe this study can help better understand progression of diseases such as emphysema and fibrosis.

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Yang, Lanti. "Mechanical properties of collagen fibrils and elastic fibers explored by AFM." Enschede : University of Twente [Host], 2008. http://doc.utwente.nl/58870.

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Vilela, Antonella Sachsida Braga. "Matriz extracelular de pericardio fibroso porcino : estudo morfologico e bioquimico." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/316956.

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Orientador: Benedicto Campos Vidal
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: Tecido pericardial tem sido utilizado na confecção de biopróteses empregadas na reparação de diferentes lesões. Entretanto, calcificações e falência mecânica têm sido as principais causas de durabilidade limitada de biopróteses cardíacas fabricadas com pericárdio bovino. Nesse trabalho foi realizado um estudo do pericárdio fibroso porcino em sua estrutura microscópica e sua natureza bioquímica. A morfologia geral e a arquitetura das fibras colágenas e elásticas foram estudadas em tecido seccionado e também em montagens totais, corados por diferentes métodos histoquímicos e analisados em microscopia de luz convencional, de polarização, de fluorescência e confocal. O estudo bioquímico da matriz pericardial foram realizados de acordo com procedimentos bioquímicos pertinentes. O pericárdio mostrou-se um tecido altamente celularizado com características de tecido jovem. Os feixes colagênicos apresentaram-se arranjados em camadas multidirecionalmente orientadas, formando uma rede de trama fechada, com um número maior de fibras orientando-se obliquamente, partindo da região central inferior em direção súpero-lateral esquerda em relação ao coração. Uma discreta predominância de fibras colágenas no sentido base-ápice foi verificada na região anterior direita do pericárdio. A matriz extracelular apresentou-se pouco metacromática. Observaram-se finas fibrilas elásticas intimamente associadas às fibras colágenas, entrelaçadas em direções diversas ou paralelas entre si. Extração comparativa de componentes da matriz não revelou diferenças entre proteínas extraídas das regiões direita e esquerda e também entre material fresco e congelado. A análise em SDS-PAGE revelou dezesseis proteínas com valores de massa molecular aparente entre 11 e 109 kDa. Análises realizadas sugerem que o GAG encontrado possivelmente é o dermatam sulfato. Os dados obtidos podem subsidiar novos procedimentos direcionados à obtenção de biomembranas melhor preparadas e funcionalmente mais adequadas à construção de biopróteses.
Abstract: Pericardial tissue has been used to construct bioprostheses employed in the repair different kinds of injuries. However, calcification and mechanical failure have been the main causes of limited durability of cardiac bioprostheses constructed with bovine pericardium. In the course of this work a study has been conducted on the porcine fibrous pericardium and its microscopic structure and its biochemical nature. The general morphology and the architecture of the collagen and elastic fibers have been studied in sectioned tissue and also total assemblies, stained by diverse histochemical methods and analyzed by conventional light, polarizing light, fluorescence and confocal microscopy. Biochemical study of the pericardial matrix was conducted according to pertinent procedures. The pericardium was shown as a highly cellularized tissue with a vascular tree very ramified and collagen fibers arranged in multidirectionally oriented layers. A predominant direction was verified, with a larger number of fibers obliquely oriented, starting at the lower central region towards high-lateral-left relatively to the heart. A discreet predominance of collagen fibers is the base-apex direction was verified in the right-front region of the pericardium. Extracellular matrix with little metachromasy was observed, indicating small quantities of acid glycosaminoglycans. Fine elastic fibrils were observed, intimately associated to collagen fibers, interlaced in various directions or parallel to themselves. No differences were found between proteins extracted from the right or left regions and between fresh or frozen material. The quantities of extracted GAGs were too small to be detected by the method used. The SDS-PAGE showed proteins with values of apparent molecular mass between 11 and 109 kDa included two polydisperse bands around 71 and 85kDa. The ectrophoretic analysis showed that the found GAG is possibly dermatan sulfate.
Doutorado
Histologia
Doutor em Biologia Celular e Estrutural

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17

Sandt, Joseph David. "Scalable manufacture and synchronized optical/mechanical characterization of tunable elastic photonic fibers." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/100094.

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Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 36-37).
In recent decades, advances in optical technologies have been essential to improvements made in the ways we transmit and process information, diagnose health issues in human patients and material problems in man-made devices and infrastructure, modify and monitor materials in manufacturing, and otherwise interact with the world around us. Optical and photonic fibers, in particular, represent a class of optical devices that are invaluable to a variety of applications. Advances in the development of optical devices will continue to provide increased utility to science and industry, though somewhat surprisingly, research related to such efforts continues to focus on a limited set of highly optimized materials, restricting the progress that could potentially be made. Increasing the breadth of materials used in optical and photonic fibers opens doors to novel capabilities of familiar technology. Herein, the mechanical and optical characterization, and attempted scaling of manufacture, of mechano-responsive, color-tunable elastic photonic fibers is discussed. When deformed, the fibers respond with a predictable, linear variation in the wavelength of light they reflect, which results in a pronounced change in their color. This characterization was accomplished with a custom-built setup designed to simultaneously collect information about stress and strain in the fiber, as well as a fiber image and spectral reflection data from selected points on the fiber. Fibers have been subjected to up to 5000 cycles of stretching and relaxation, and initial results indicate that their optical response to longitudinal strain can be exceptionally consistent, even after several thousand cycles. Sensors that rely on optical technologies have several inherent advantages over more traditional resistance-based sensors and other systems, including being lightweight, immune to electromagnetic interference, and inexpensive. Once a viable method of manufacturing fibers with length on the order of meters or kilometers is found, the fibers have great potential to find application in medicine, structural health monitoring, textiles, communication, and other industries. The vast potential of these fibers comes from the use of novel, elastic materials in the implementation of well-known optical concepts.
by Joseph David Sandt.
S.M.

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18

Hegg, Meredith Michelle. "Exact Relations and Links for Fiber-Reinforced Elastic Composites." Diss., Temple University Libraries, 2012. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/164322.

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Mathematics
Ph.D.
Predicting the effective elastic properties of a composite material based on the elastic properties of the constituent materials is extremely difficult, even when the microstructure is known. However, there are cases where certain properties in constituents always carry over to a composite, regardless of the microstructure of the composite. We call such instances exact relations. The general theory of exact relations allows us to find all of these instances in a wide variety of contexts including elasticity, conductivity, and piezoelectricity. We combine this theory with ideas from representation theory to find all exact relations for fiber-reinforced polycrystalline composites. We further extend these ideas to the concept of links. When two composites have the same microstructure but different constituent materials, their effective tensors may be related. We use the theory of exact relations to find such relations, which we call links. In this work we describe a special set of links between elasticity tensors of fiber-reinforced polycrystalline composites. These links allow us to generalize certain results from specific examples to generate new information about this widely-used class of composites. In particular, we apply the link to obtain information about composites made from two transversely isotropic materials and polycrystals made from one orthotropic material.
Temple University--Theses

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19

Braga, Guilherme Gambogi 1985. "Avaliação da elastogênese em cultura de células obtidas de camungongos deficientes em Fibrilina-1 : estudo do efeito do Losatan." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/314063.

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Orientador: Claudio Chrysostomo Werneck
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: Fibrilina-1 é um importante componente da rede de microfibrilas da matriz extracelular. As microfibrilas estão presentes nas fibras elásticas que são responsáveis pela elasticidade e resistência de tecidos dos pulmões, pele e grandes vasos. Mutações no gene da Fibrilina-1 estão associadas com a síndrome de Marfan. Pacientes com esta síndrome apresentam muitas manifestações clínicas nos pulmões, sistema cardiovascular e olhos. Modelos de síndrome de Marfan tem sido criados no sentido de obter informações sobre o desenvolvimento desta doença. Estudos recentes em modelos de camundongos tem sugerido a importância da atividade exacerbada do TGF ? promovendo a quase totalidade das alterações fenotípicas encontradas nestes camundongos, o que pode ser revertido pelo tratamento com o Losartan. O principal objetivo deste projeto foi avaliar a formação de fibras elásticas em cultura de células obtidas de animais deficientes em fibrilina-1, bem como o possível efeito do tratamento destas células com losartan. Os fibroblastos derivados de animais deficientes em fibrilina- 1 foram estudados usando imunofluorescência, western blotting, microscopia eletrônica de varredura e transmissão e real-time PCR. Assim, a deficiência em fibrilina-1 ocasionou uma redução conjunta da deposição de fibrilina-2, MAGP-1 e tropoelastina na matriz extracelular em cultura de fibroblastos de derme. Foi possível verificar aumento no níveis de expressão das metaloproteinases MMP-2 e MMP-9. O tratamento dos fibroblastos derivados de animais deficientes em fibrilina-1 com o fármaco losartan levou a recuperação parcial da deposição das proteínas Fibrilina-2, MAGP-1 e tropoelastina na matriz extracelular de cultura in vitro. Porém, o tratamento dos fibroblastos derivados de animais deficientes em fibrilina-1 com fármaco Captopril e os peptídeos de Angiotensina I e II não influenciaram na deposição das mesmas na matriz extracelular de cultura in vitro
Abstract: Fibrillin-1 is an important microfibril network component. Microfibrils are present in elastic fiber responsible for resilience and elastic properties from structures like lungs, skin and large vessels. Mutations in Fibrillin-1 gene are associated with Marfan's Syndrome. Marfan's Syndrome patients shown many different clinical manifestations in lungs, cardiovascular system and eyes tissues. Marfan's models have been created to get better insights about this disease development. Recent studies from mice models have suggested an important role to unbalanced TGF ? activity promoting almost whole alterations found in those mice which might be rescued by losartan treatment. Our main goal were evaluate elastic fiber formation in cell culture obtained from fibrillin-1 defficient mice as well as losartan's treatment effect on those cells. The fibroblasts derived from deficient animals in fibrillin-1 were studied using immunofluorescence, western blotting, scanning electron microscopy and transmission and real-time PCR. Thus, the deficiency in fibrillin-1 led to a joint reduction of the deposition of fibrillin-2, MAGP-1 and tropoelastin in the extracellular matrix in culture of fibroblasts in the dermis. It was possible to observe an increase in levels of expression of metalloproteinases MMP-2 and MMP-9 were found. The treatment of the fibroblasts derived from deficient animals in fibrillin-1 with the drug losartan has led to the partial recovery of the deposition of protein fibrillin-2, MAGP-1 and tropoelastin in the extracellular matrix of culture in vitro. However, the treatment of fibroblasts derived from deficient animals in fibrillin-1 with drug Captopril and the peptides of Angiotensin I and II not influenced in the deposition of the same in the extracellular matrix of culture in vitro
Mestrado
Bioquimica
Mestre em Biologia Funcional e Molecular

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20

Soares, Leila Cristina. "Composição da matriz extracelular do ligamento cardinal de mulheres na pós-menopausa com e sem prolapso uterino." Universidade do Estado do Rio de Janeiro, 2011. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=2497.

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O prolapso uterino tem sua incidência aumentada na pós-menopausa. O objetivo deste estudo é identificar as alterações na matriz extracelular do ligamento cardinal associadas à menopausa e ao prolapso uterino. Ligamento cardinal de três diferentes grupos de mulheres, pré-menopausa, prolapso uterino e pós-menopausa, foram identificados e biopsiados durante 57 histerectomias abdominais ou vaginais. As amostras foram processadas por métodos bioquímicos para caracterização e quantificação de glicosaminoglicanos sulfatados e colágeno. As concentrações relativas de glicosaminoglicanos foram obtidas por eletroforese. Procedimentos histológicos foram feitos para identificar fibras elásticas (Weigert), distribuição de colágeno (Picro Sirius) e decorin (imunohistoquímica). Nossos resultados mostraram aumento na concentração de GAG de 72,2%, redução na concentração de colágeno de 37% e diminuição de 22% de fibras elásticas no grupo de prolapso uterino quando comparado ao grupo da pós-menopausa (p<0,05, p<0,04 e p<0,05 respectivamente). As concentrações relativas de glicosaminoglicanos sulfatados para condroitin sulfato, heparan sulfato e dermatan sulfato não mostraram diferenças entre os três grupos. A organização do colágeno foi similar entre os três grupos e a marcação do decorin pareceu estar diminuída no grupo de prolapso uterino. Nossos resultados indicam alterações no metabolismo do tecido conjuntivo. O ligamento cardinal da mulher na pós-menopausa possui uma matriz extracelular mais densa. Esta alteração não ocorre na mulher com prolapso uterino.
Uterine prolapse has increase of incidence after menopause. The aim of this study was to identify the changes in extracellular matrix of cardinal ligaments associated to menopause and uterine prolapse. Cardinal ligament of 3 different groups (pre-menopause, menopause and uterine prolapse) are identified and biopsied during 57 womens abdominal or vaginal hysterectomy. Biopsy specimens were assessed by biochemical methods to characterize and quantify sulfated glycosaminoglycans and collagen. Relative concentrations of GAG were obtained by electrophoresis. Histological procedures are made to identify elastic fibers (Weigert) collagen distribution (Picro sirius) and decorin (immunohistochemistry). Our results showed increase in GAG concentration 72.2% in uterine prolapse group compared to menopause group (p<0.05). Collagen concentration was 37% lower in uterine prolapse group compared to menopause group (p<0.04). Relative concentration of GAG: heparan sulfate, chondroitin sulfate and dermatan sulfate showed no differences among three groups. Elastic fibers showed a significant reduction of approximately 22% uterine prolapse group compared to menopause group (p<0.05). Collagen organization was similar in three groups and the staining pattern of decorin seemed to be decreased in uterine prolapse group. Our results indicate changes in connective tissue metabolism. Cardinal ligament in postmenopausal women has a denser extracellular matrix. This change is not observed in women with uterine prolapse.

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21

Alves, Calebe de Andrade. "A study concerning homeostasis and population development of colagen fibers." reponame:Repositório Institucional da UFC, 2017. http://www.repositorio.ufc.br/handle/riufc/27811.

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ALVES, C. A. A study concerning homeostasis and population development of collagen ﬁbers. 2017. 88 f. Tese (Doutorado em Física) – Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2017.
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Collagen is a generic name for the group of the most common proteins in mammals. It confers mechanical stability, strength and toughness to the tissues, in a large number of species. In this work we investigate two properties of collagen that explain in part the choice by natural selection of this substance as an essential building material. In the ﬁrst study the property under investigation is the homeostasis of a single ﬁber, i.e., the maintenance of its elastic properties under the action of collagen monomers that contribute to its stiﬀening and enzymes that digest it. The model used for this purpose is a onedimensional chain of linearly elastic springs in series coupled with layers of sites. Particles representing monomers and enzymes can diﬀuse along these layers and interact with the springs according to speciﬁed rules. The predicted lognormal distribution for the local stiﬀness is compared to experimental data from electronic microscopy images and a good concordance is found. The second part of this work deals with the distribution of sizes among multiple collagen ﬁbers, which is found to be bimodal, hypothetically because it leads to a compromise between stiﬀness and toughness of the bundle of ﬁbers. We propose a mechanism for the evolution of the ﬁber population which includes growth, fusion and birth of ﬁbers and write a Population Balance Equation for that. By performing a parameter estimation over a set of Monte Carlo simulations, we determine the parameters that best ﬁt the available data.
Collagen is a generic name for the group of the most common proteins in mammals. It confers mechanical stability, strength and toughness to the tissues, in a large number of species. In this work we investigate two properties of collagen that explain in part the choice by natural selection of this substance as an essential building material. In the ﬁrst study the property under investigation is the homeostasis of a single ﬁber, i.e., the maintenance of its elastic properties under the action of collagen monomers that contribute to its stiﬀening and enzymes that digest it. The model used for this purpose is a onedimensional chain of linearly elastic springs in series coupled with layers of sites. Particles representing monomers and enzymes can diﬀuse along these layers and interact with the springs according to speciﬁed rules. The predicted lognormal distribution for the local stiﬀness is compared to experimental data from electronic microscopy images and a good concordance is found. The second part of this work deals with the distribution of sizes among multiple collagen ﬁbers, which is found to be bimodal, hypothetically because it leads to a compromise between stiﬀness and toughness of the bundle of ﬁbers. We propose a mechanism for the evolution of the ﬁber population which includes growth, fusion and birth of ﬁbers and write a Population Balance Equation for that. By performing a parameter estimation over a set of Monte Carlo simulations, we determine the parameters that best ﬁt the available data.

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22

Dyer, S. J. R. "Elastic anisotropy in fibre reinforced composites." Thesis, University of Leeds, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373548.

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23

Aya, Rino. "Regeneration of elastic fibers by three-dimensional culture on a collagen scaffold and the addition of latent TGF-β binding protein 4 to improve elastic matrix deposition." Kyoto University, 2016. http://hdl.handle.net/2433/215396.

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24

Fink, Gisele Miozzo. "Estudo da distribuição diferencial das fibras do sistema elástico no ventrículo esquerdo do coração de ratos normais." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/5/5160/tde-16062009-162743/.

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A elasticidade do tecido conjuntivo desempenha uma função protetora agindo como uma mola tênsil durante o trabalho muscular, No entanto, existem poucos estudos sobre a distribuição das fibras do sistema elástico no coração. Considerando que: a) o estudo da distribuição destas fibras pode ajudar a compreender a mecânica cardíaca, e b) o rato tem sido usado como o melhor modelo animal para as disfunções cardiovasculares, o objetivo deste estudo é apresentar uma descrição sistemática da distribuição diferencial das fibras do sistema elástico do endocárdio, epicárdio e miocárdio ventricular. Cortes histológicos de ventrículo esquerdo obtido de ratos normais adultos foram estudados pela comparação do padrão ultraestrutural de cada um dos tipos fibrilares com coloração pela técnica da resorcina-fucsina com prévia oxidação, para microscopia de luz. As observações ultra-estruturais foram feitas em tecidos fixados com ácido tânico - glutaraldeído, que permite a identificação mais precisa das fibras oxitalânicas, elaunínicas e elásticas. Foi aplicado um sistema semiquantitativo de avaliação. A análise dos cortes histológicos corados pela Resorcina-fucsina com oxidação prévia mostrou um estrato de fibras elásticas em estreita associação ao endotélio no endocárdio e ao mesotélio no epicárdio. Quando observado ao microscópio eletrônico é possível identificar que nestas ambas localizações as fibras do sistema elástico estão arranjadas em dois estratos dispostos ortogonalmente. Ao nível ultraestrutural, notou-se a distribuição diferencial das fibras do sistema elástico nos três compartimentos do tecido conjuntivo associado ao miocárdio propriamente dito: epimísio, perimísio e endomísio. O epimísio apresenta fibroblastos, fibras colágenas grossas, fibras elaunínicas e elásticas entremeadas à substância amorfa. No perimísio, a microscopia eletrônica mostrou uma grande quantidade de microfibrilas associadas a fibras elásticas, elaunínicas e mesmo fibras colagênicas. Freqüentemente, neste compartimento, as microfibrilas estão compactadas formando feixes que correspondem ao padrão ultra-estrutural das fibras oxitalânicas. O endomísio é rico em fibras oxitalânicas associadas à lâmina basal dos cardiomiócitos. Uma rede microfilamentar conecta os elementos do endomísio entre si. Ainda que as implicações funcionais sejam especulativas, a distribuição diferencial das fibras do sistema elástico nos compartimentos da parede ventricular sugere que diferenças na elasticidade conferem versatilidade biomecânica ao tecido como um todo. A análise ultra-estrutural mostra que as fibras oxitalânicas (menos elásticas) se co-localizam com fibras colagênicas finas no endomísio e perimísio, enquanto que a presença de fibrilas colágenas mais grossas coincide com fibras elásticas e elaunínicas (com mais elasticidade) no endo- e epicárdio. Estas observações sugerem que o sistema elástico, em co-evolução com o sistema colagênico, contribui para acomodar a diversidade funcional
The connective tissue elasticity has a protective function acting as a tensile spring during muscular work. Nevertheless, few is known about the distribution of the elastic system fibers in the heart. Considering that a) the study of the distribution of these fibers may help understand the cardiac mechanics, and b) rat models are used to study cardiac dysfunctions, our aim is to study the distribution of elastic system fibers in the ventricular endocardium, epicardium and myocardium of normal rats. Histological tissue sections of left ventricle (obtained from adult rats) were studied by comparing the typical ultrastructural picture of each of the fiber types with Resorcinfuchsin staining technique for light microscopy. The ultrastructural observation was made in tissues fixed with tannic acid-glutaraldehyde, which provided a reliable means to identify the elastic system fibers, as oxytalan, elaunin and elastic fibers. A semiquantitative evaluation was performed. The analysis of the histological sections stained by Resorcin-fuchsin technique after oxidation shows a stratum of elastic system fibers in close association to the endothelium in the endocardium and to the mesothelium in the epicardium. When observed at the transmission electron microscope, it was possible to see that in both locations the elastic system fibers are arranged in two orthogonally disposed layers. At the ultrastructural level, the epimysium presents fibroblasts, thick collagen, elaunin and elastic fibers interspersed in the amorphous substance. In the perimysium, the electron microscope disclosed a great amount of microfibrils, surrounding all fibrilar components: elastic fibers, elaunin fibers and even collagen fibers. Frequently, at this location, the microfibrils are closely packed, forming bundles devoid of elastin that correspond to the ultrasctructural picture of the oxytalan fibers. The endomysium is rich in oxytalan fibers in a close association with the basal lamina of the myocytes. A microfibrilar network interconnects the endomysium elements each other. In spite of the functional implications being speculative, the differential distribution of the elastic system fibers in the compartments of the ventricular wall suggests that the differences in elasticity provide biomechanical versatility to the intire system. Ultrastructural analysis shows that oxytalan fibres and thin collagen fibrils are co-localized in endomysium and perimysium, whereas, the presence of thicker collagen fibrils coincides with elaunin and elastic fibers in endo- and epicardium. These specific co-localizations suggest that elastic system, in co-evolution with collagen, has contributed to accommodating functional diversity

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25

Zhang, Xu. "Fabrication, Characterization, and Application of Elastic Hydrophobic Electrospun Fiber Mats." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1481017775403681.

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26

Armani, Andre. "A influência da emissão sonora nos constituintes da lâmina própria da prega ventricular." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/17/17151/tde-20072016-093512/.

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As pregas vocais (PV) são estruturas únicas, altamente especializadas na vibração para a produção sonora. Em grande parte, decorrente da estruturação em camadas da lâmina própria (LP). Essa estruturação não está presente ao nascimento, somente após anos de uso vibratório e fonatório da PV é que a LP está finalmente estruturada. As pregas ventriculares (PVT) não são, habitualmente, estruturas vibratórias na produção sonora, e possuem a LP menos organizada em estratos, sendo menos especializadas para a vibração. Até o presente momento, não se tem conhecimento do que ocorre com os constituintes da LP de PVTs de pessoas que as utilizam como fonte produtora de voz. No presente estudo, foram comparados os constituintes colágenos e as fibras elásticas da LP de PVTs de indivíduos que as utilizam como principal fonte vibratória na produção de voz com o grupo controle. Foram selecionados seis indivíduos que utilizavam pelo menos uma das PVTs como fonte de vibração para a produção sonora por ao menos seis anos. Delas, colheu-se pequeno fragmento (0,5 cm2), que após processamento histológico, as fibras colágenas foram coradas com Picrosirus Red e as fibras elásticas com Weigert resorcina-fucsina. Foram obtidas 54 imagens da camada mais superficial da LP de cada PVT para cada coloração. Após a aquisição das imagens, as fibras colágenas tipo I e tipo III, colágenas totais e fibras elásticas foram quantificadas utilizando-se o software Image-Pro Plus, e comparadas com as PVTs dos controles. A análise estatística foi realizada por meio do teste T de Student para amostras não pareadas. A porcentagem de colágeno total na camada mais superficial da LP de PVT utilizada como fonte vibratória para a produção de som foi significativamente maior em relação aos controles. O mesmo ocorreu com a quantidade de colágeno tipo I. Não houve diferenças na quantidade de colágeno tipo III e de fibras elásticas. Como conclusão, pode-se afirmar que a utilização da PVT como fonte vibratória produtora de som leva ao aumento da quantidade de fibras colágenas totais e do tipo I na camada mais superficial da sua LP
The vocal folds (VF) are unique structures, highly specialized in vibrating for sound production. This specialization is mainly due to a layered structure of the lamina propria (LP). This layered structure is not present at birth, and develops only after a several years of phonation. The LP of the mature vocal fold consists of three layers. The ventricular folds (VTF) are not originally vibrating structures for sound production, and in its LP the layers are poorly organized. It is not known what happens to the constituents of the LP in the VTF in subjects that use VTF vibration as a source of voice production. In the present study, the distribution and quantity of collagen and elastic fibers of the lamina propria from VTF of patients that use it as the main source of vibration for voice production were compared with the VTF from control subjects. Six individuals that used at least one of the VTF as source of vibration for sound production for minimum of six years were selected. A small fragment of VTF (0.5 cm2) used as vibration source of sound production was collected from each subject. The samples were processed for histological analysis. Collagen fibers were stained with Picrosirus Red and elastic fibers were stained with Weigert\'s Resorcin-Fuchsin. A total of 54 images were obtained from the superficial layer of the LP from each VTF for each stain. After image acquisition, collagen type I, III, total collagen and elastic fibers were quantified and compared with the VTF from the control group. Quantification was done using Image-Pro Plus software. Statistics were performed using an unpaired Student T test. The amount of total collagen in the most superficial layer of LP when the VTF was used as the source of vibration for the production of sound was significantly higher when compared to controls. The same result was seen for the amount of type I collagen in both groups. There was no difference in the quantity of type III collagen and elastic fibers between the two groups. Vibration of the VTF as a source of sound, for at least six years, leads to an increase in the amount of total collagen fibers and an increase in type I collagen, but does not increase the amount of type III collagen and elastic fibers in the most superficial layer of LP. These results may help elucidate the unique development of the lamina propria of the vocal fold

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27

Gudienė, Devika. "Su amžiumi susiję žmogaus pamatinės arterijos struktūros pokyčiai." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2008. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2008~D_20080827_131740-59360.

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Darbo tikslas - Įvertinti su amžiumi susijusius struktūrinius žmogaus pamatinės arterijos sienelės pokyčius. Darbo uždaviniai: 1. Ištirti pamatinės arterijos medijos kolageninių skaidulų kiekybinius pokyčius; 2. Nustatyti pamatinės arterijos sienelės medijos raumeninių ląstelių kiekybinius pokyčius; 3. Ištirti pamatinės arterijos sienelės medijoje esančių elastinių skaidulų kiekybinius pokyčius; 4. Ištirti pamatinės arterijos sienelės medijos storio pokyčius; 5. Nustatyti žmogaus pamatinės arterijos intimos, vidinės elastinės membranos struktūrinius pokyčius; 6. Įvertinti kiekybinių histologinių pokyčių tarpusavio priklausomybę bei sąsają su amžiumi. Mokslinis naujumas Galvos smegenų kraujotakos sutrikimai yra viena iš priežasčių, lemiančių didžiausią mirtingumą ir neįgalumą. Epidemiologiniai tyrimai rodo, kad sergamumas ir mirtingumas dėl galvos smegenų kraujotakos sutrikimų tarp vyresnio amžiaus asmenų turi tendenciją sparčiai didėti. Šiame darbe žmogaus galvos smegenų pamatinės arterijos sienelės struktūros pokyčiai vertinti amžiniu aspektu. Histomorfometriškai analizuota medžiaga leido įvertinti bendruosius pamatinės smegenų arterijos sienelės ypatumus, susijusius su amžiumi. Histomorfometriškai įvertinome pamatinės arterijos medijos elastinių ir kolageninių skaidulų bei raumeninių ląstelių kiekybinius pokyčius susijusius su amžiumi skirtingose amžiaus grupėse. Tyrimo metu nagrinėjome ne tik elastinių skaidulų ir kolageno tinklo plotą, bet apskaičiavome ir skaidulų... [toliau žr. visą tekstą]
The aim of the investigation was to examine and evaluate age-related structural changes in media of human basilar artery The main objectives of the thesis were as follows: 1. To examine the quantitative changes in the collagen fibres in media of basilar artery; 2. To evaluate the quantitative changes in muscular cells in the media of basilar artery; 3. To evaluate the quantitative changes in the elastic fibres in the media of basilar artery; 4. To evaluate the changes in the thickness of the tunica media; 5. To examine the structural changes in the human basilar artery intima and internal elastic membrane; 6. To assess the relation of different quantitative histological changes and to determine their correlation with age. Academic novelity of the investigation Cerebrovascular diseases cause huge mortality and disablement. Epidemiologic research has revealed that the morbidity and mortality rates due to cerebrovascular diseases tend to increase. We evaluated basilar artery wall structural changes occuring while ageing. Histomorphometrically analysed material enabled to evaluate general cerebral artery wall peculiarities related to age. We evaluated histomorphometrically quantitative changes of elastic and collagen fibres, muscular cells in ageing in different age groups. We also made analysis not only of elastic and collagen fibres area, but also of perimeter and number of fibres. We analyzed the changes in the thickness of the tunica media. We examined the structural... [to full text]

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Ishiko, Toshihiro. "Chondroitinase injection improves keloid pathology by reorganizing the extracellular matrix with regenerated elastic fibers." Kyoto University, 2013. http://hdl.handle.net/2433/179347.

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Machado, Denise. "Caracterização do domínio da glicoproteína associada a microfibrila-1 (MAGP-1) com atividade pró-trombótica." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/314065.

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Orientador: Cláudio Chrysóstomo Werneck
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia
Made available in DSpace on 2018-08-16T09:01:31Z (GMT). No. of bitstreams: 1 Machado_Denise_M.pdf: 1404386 bytes, checksum: e811cae8e94f35d5b473fe2881261fd8 (MD5) Previous issue date: 2010
Resumo: Nos últimos anos, o principal objetivo de nosso laboratório é esclarecer a participação da GlicoProteína Associada a Microfibrila-1 (MAGP-1) na formação de trombos no modelo de trombose arterial fotoquímica. Dados indicam que a MAGP-1 não interage diretamente com as plaquetas, importante componente na trombose arterial, mas que, provavelmente, a MAGP-1 esteja interagindo com uma molécula que tenha participação neste processo. Neste sentido, a interação da MAGP-1 com moléculas importantes na formação do trombo foi estudada. A MAGP-1 tem a capacidade de interagir com o fator de von Willebrand, bem como com fibrinogênio e fibronectina. Além disto, foi verificado que a injeção da MAGP-1 recombinante em camundongos deficientes em MAGP-1 é capaz de reestabelecer o tempo normal de formação de trombos nestes animais. Considerando a ausência da MAGP-1 e seu efeito na formação de trombos, foi questionado se a morfologia dos trombos obtidos em camundongos deficientes em MAGP-1 era diferente dos trombos obtidos em camundongos selvagens. Dados iniciais sugeriam que os trombos de camundongos deficientes em MAGP-1 apresentavam ultraestrutura diferente, onde um número maior de plaquetas apresentavam aparentemente, os seus grânulos e corpos densos intactos, sugerindo uma ativação ineficiente na ausência de MAGP-1. No presente trabalho, além de análise ultraestrutural mais detalhada, foram feitos estudos para determinar qual a região da MAGP-1 é responsável pela atividade trombogênica. Neste sentido, proteínas mutadas, truncadas e peptídeos derivados da MAGP-1 foram obtidos e então injetados nos camundongos selvagens e deficientes em MAGP-1. Como resultados, pudemos observar que os trombos dos camundongos selvagens bem como dos camundongos deficientes em MAGP-1 apresentam basicamente a mesma morfologia, levando em consideração as técnicas utilizadas, microscopia eletrônica de transmissão e varredura. Em relação ao mapeamento dos domínios, quando utilizada a molécula inteira, seja de camundongo, seja bovina, o tempo normal de oclusão foi reestabelecido. A injeção da forma truncada da região carboxiterminal foi suficiente para obter este mesmo resultado que está principalmente relacionado a um peptídeo também determinado. O mecanismo pelo qual este peptídeo atua normalizando o tempo de oclusão normal ainda não é conhecido e será objeto de estudos futuros
Abstract: In the last years, the main purpose of our laboratory has been to clarify the participation of the Microfibril-Associated GlycoProtein-1 (MAGP-1) in forming thrombus in photochemically-induced artery thrombosis model. It was considered that MAGP-1 does not interact directly with platelets, important component in artery thrombosis and probably MAGP-1 is interacting with a molecule which has participation in this process. In this sense, the interaction of the MAGP-1 with important molecules in the thrombus formation was studied. The MAGP-1 has the ability to interact with von Willebrand factor, as well as with fibrinogen and fibronectin. In addition, it was verified that the injection of recombinant MAGP-1 in MAGP-1-deficient mice was able to restores normal time of thrombus formation in these animals. Considering the MAGP-1 absence and its effect on the thrombi formation, it was questioned whether thrombi morphology obtained from MAGP-1-deficient mice was different from thrombi obtained from wild-type mice. Initial data suggested that the thrombi from MAGP-1-deficient mice had different structure, where platelets apparently showed their intact granules and dense bodies, suggesting an inefficient activation in the MAGP-1 absence. In this work, besides the ultra-structural analysis, more detailed studies have been made to determine which region of the MAGP-1 is responsible for the thrombogenic activity. In this sense, truncated proteins, mutated proteins and peptides, were obtained and then injected into MAGP-1-deficient mice to verify their activities. As result, we noticed that the thrombi have similar structure taking into consideration used techniques, scanning electron microscopy and transmission electron microscopy. Furthermore, in relation to MAGP-1 mapping domains studies when we inject recombinant full-length molecule either mice or bovine, the normal time occlusion was restored. The injection of carboxy-terminal region was enough to get this same result what is mainly related to an also determined peptide. Mechanisms involved in this process are unknown and will be our aim in the future studies
Mestrado
Bioquimica
Mestre em Biologia Funcional e Molecular

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30

Edginton, Ryan Stuart. "The multiscale biomechanics and mechanochemistry of the extracellular matrix protein fibres, collagen & elastin." Thesis, University of Exeter, 2018. http://hdl.handle.net/10871/34619.

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Collagen is the most abundant protein in the animal kingdom and, together with elastin, forms extensive fibrous networks that constitute the primary structure of the mammalian extracellular matrix, respectively endowing it with the tensile and elastic properties that fulfil its principal role as the passive framework of the body. The fibrous proteins are distinctly hierarchically organised from the molecular scale upwards; for example, the nanoscale tropocollagen monomer assembles in arrays that form the micrometer scale microfibrils and fibrils, and thence into collections of millimetre scale collagen fibres, that in-turn, constitute functional tissues such as skin, tendon and bone. Much is known about the structure at each of these individual scales – collagen being the most extensively researched – and the macromechanics of the fibres are well established. However, far less is known about the micromechanics of these proteins, in particular how the monomers influence the functional mechanics of the macroscopic fibres. In this thesis, I explore the multiscale mechanics of collagen and elastin fibres over a range of hydrations – with fibres in direct contact with aqueous solution, and progressively dehydrated in humidity-controlled environments. I use quasi-static tensile testing to probe the macroscopic mechanical response (Young’s modulus and stress relaxation) of the fibres, and employ Brillouin and Raman microscopy to assess the longitudinal modulus in the GHz range and corresponding molecular properties of the proteins. Brillouin microscopy is an emerging technique in the biomedical field. It enables the all-optical, contact-free and non-destructive testing of tissue micromechanics through detection of frequency shifted light scattered off thermally excited acoustic waves or “phonons” in the GHz range. As one of the first studies of Brillouin light scattering in these fibres, it sets the basis for further investigation of tissue biomechanics. In particular, I provide the full description of the protein fibre micromechanics by performing angular measurements using a so-called platelet-like configuration with sample mounted onto a reflective substrate at 45° angle to the excitation beam. I derive the high-frequency longitudinal modulus, and discuss the results in comparison to the Young’s modulus, in terms of the different frequency and spatial scale of the measurements. I obtained a full description of elasticity using Brillouin spectroscopy applied to dried fibres; however, obtaining the same description in hydrated fibres is a challenge, as the Brillouin spectrum is dominated by water. An assessment of the mechanical differences between type-I and type-II collagens is also given here. Water is known to be a primary determinant of tissue biomechanics, and I identified for the first time, the critical hydration ranges between 100 and 85% relative humidity (RH) for collagen, and around 85% RH for elastin, at which point each macroscopic fibre switched from viscoelastic to plastic-like behaviour. Dehydration below these critical points was shown to severely diminish collagen fibrillar sliding, and completely rob elastin of its ability to reversibly deform under strain. The Young’s modulus increased markedly below these hydrations, and I observed a parallel increase in the longitudinal modulus at high frequencies in each protein, indicating a concomitant increase in stiffness at the two scales. The major difference observed between the two fibrous proteins is that, in the case of elastin, I observe a two-fold increase in the longitudinal modulus as the hydration is decreased from 100 to 21% RH, whilst the Young’s modulus increases by two orders of magnitude. This discrepancy was not observed in collagen, which confirmed that the protein maintained its long-range order in the form of the triple helix at all hydrations employed in this work, whilst the elastin ultrastructure experiences a liquid-to-solid state change at a critical hydration. I demonstrate through the analysis of the low-wavenumber region (< 500 cm-1) of the Raman spectrum, that the increase in molecular stiffness of both proteins, is reflected in an increase in torsional rigidity of the peptide backbone upon dehydration. Moreover in collagen, I observe a reduction in the number of inter-protein water bridges, which I propose causes a collapse of the lateral spacing between monomers and an increase in direct backbone-backbone hydrogen bonding, that further stiffens the fibre. Small strain induced reorientations of the amide III and C–C stretching modes in dehydrated collagen fibres suggest that macroscopic stresses may be transferred to the triple helix, otherwise left unperturbed in the hydrated state. I postulate that this is a result of the degraded intra- and interfibrillar sliding mechanism below the critical hydration. Hence in its dehydrated state, the collagen whole-fibre mechanics are similar to those at the molecular scale. The role of proteoglycans and glycosaminoglycans and their potential connection to hydration, is also discussed. In agreement with previous work, I found no Raman spectral changes as a result of stretching hydrated elastin fibres, indicating that even large strains e.g. 80%, have no significant effect on the structural scale probed by Raman microscopy, nor in the air-dried state where the brittle fibres break at low strains. I suggest this may imply a limited sensitivity of Raman bands to these changes, possibly an indication of elastin’s dynamic ultrastructure, or that stress is dissipated at a higher level of the fibre structure. On the macroscopic scale, it is the poroelastic nature of elastin which controls the stress relaxation under strain, and the elastic recovery is mediated by an interplay of hydrophobic interactions and hydration forces.

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Korkmaz, Ayşe Hilal Usal Melek. "Fiber takviyeli elastik malzemelerin sürekli ortam hasar mekaniğine dayalı bünye denklemlerinin modellenmesi /." Isparta : SDÜ Fen Bilimleri Enstitüsü, 2009. http://tez.sdu.edu.tr/Tezler/TF01328.pdf.

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32

Parietti, Lucie. "Micromechanical finite element model for constitutive elastoplastic analysis of unidirectional fiber-reinforced composites." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06232009-063447/.

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33

Simpson, Andreja. "Fibulin-4 mutations in cutis laxa." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/fibulin4-mutations-in-cutis-laxa(fcf5936a-e6a4-42a0-b58a-a16876b0f01f).html.

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Fibulin-4 is an extracellular matrix protein which plays an essential function in the assembly of elastic fibres, and may be involved in the modulation of TGFβ bioavailability and smooth muscle cell differentiation. Mutations in fibulin-4 can cause autosomal recessive cutis laxa, a frequently lethal connective tissue disorder. Although patient studies have provided some insights into the pathological mechanisms of this disease, a detailed analysis of the consequences of fibulin-4 mutations on a molecular and cellular level was required.The findings presented in this thesis demonstrate that cutis laxa-causing fibulin-4 mutations may lead to reduced extracellular levels of fibulin-4 due to its increased susceptibility to protease degradation and misfolding/aggregation. An accumulation of autophagic vesicles was observed, indicating a blockage of autophagy, possibly due to intracellular accumulation of aggregated/misfolded mutant protein. In the extracellular matrix, mutations affected the ability of fibulin-4 to interact with the major components of the elastic fibre assembly, heparin, LTBP-1 and fibronectin. In addition, fibulin-4 mutations generally reduced expression levels of elastic fibre assembly components. In summary, these findings contribute to the understanding of fibulin-4 associated cutis laxa, and provide a basis upon which future therapeutic interventions may be developed.

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Lorion, Chloé. "Développement, caractérisation et potentiels thérapeutiques d’Elactiv’, une protéine élastique biomimétique, inspirée de la tropoélastine humaine." Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10312/document.

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Les peptides élastiques (ELP, Elastin-like peptide) sont d'excellents exemples de polymères biomimétiques récemment proposés en médecine régénérative, en particulier dans le domaine de l'ingénierie tissulaire des tissus mous (peau, vaisseaux sanguins, poumons…) pour lesquels la modélisation est complexe car l'instruction correcte des cellules nécessite une élasticité fonctionnelle. L'ajustement précis de la structure primaire des ELP peut moduler voire améliorer les propriétés physico-chimiques, structurales et fonctionnelles de la protéine native. De plus, la capacité des ELP à ajuster leurs caractéristiques physico-chimiques en réponse à des stimuli externes (température, pH), les définit comme des polymères intelligents. Ces polymères bioactifs offrent ainsi une large gamme d'applications très prometteuses encore très peu explorées dans les technologies d'ingénierie tissulaire et les systèmes d'administration de médicaments. Dans ce travail de thèse, nous avons développé, caractérisé et évalué les potentiels thérapeutiques d'une protéine élastique synthétique, Elactiv', inspirée de la structure unique de la tropoélastine humaine, précurseur soluble de l'élastine. Elactiv' conserve les caractéristiques physico-chimiques (comportement thermosensible, propriétés d'autoassemblage) et les fonctions biologiques de la protéine native (prolifération, différenciation et survie des fibroblastes dermiques et kératinocytes humains, sensibilité à la dégradation enzymatique). De plus, Elactiv' possède la particularité in vitro de s'incorporer dans les fibres élastiques néo-synthétisées par des fibroblastes dermiques sains, et d'induire la synthèse de tropoélastine fibrillaire par des fibroblastes pathologiques, syndrome de Williams-Beuren, qui ne synthétisent pas ou très peu de fibres élastiques. Un hydrogel formé exclusivement d'Elactiv' a permis d'accéder aux propriétés mécaniques de l'ensemble et de vérifier sa biocompatibilité in vitro et son innocuité et sa résorption in vivo. Enfin, l'association de la protéine Elactiv' aux dendrigrafts de poly(L-lysine), polymères synthétiques hautement fonctionnalisables, a permis de faire évoluer l'architecture de l'hydrogel vers un biomatériau hybride dans le but d'augmenter ses propriétés mécaniques et biologiques. Ainsi, les potentiels biomimétiques et thérapeutiques de la protéine Elactiv' en font un candidat prometteur pour la régénération des tissus mous
Elastin-like peptides are excellent examples of biomimetic polymers recently proposed in regenerative medicine, particularly for soft tissue engineering (skin, blood vessels, lung ...) for which modeling is a complex task requiring functional elasticity to insctruct cells properelly. Fine-tuning of ELP’s primary structure can modulate or improve physicochemical, structural and functional properties of the native protein. In addition, the adjustment of ELP physicochemical characteristics through external stimuli (temperature, pH) defined them as intelligent polymers. These bioactive polymers thus provide a wide range of very promising applications in tissue engineering and drug delivery, although this has been under-explored until then. In this thesis, we have developed, characterized and evaluated therapeutic potentials of Elactiv', a synthetic elastic protein inspired by the unique structure of the human tropoelastin, the soluble precursor of elastin. Elactiv’ retains physicochemical characteristics (thermoresponsive behavior, self-assembly properties) and biological functions of the native protein (proliferation, differentiation and survival of human keratinocytes and dermal fibroblasts, susceptibility to enzymatic degradation). Besides, Elactiv’ is able to incorporate into neosynthesized elastic fibers by healthy dermal fibroblasts, and to induce fibrillar tropoelastin synthesis by pathological fibroblasts, Williams-Beuren syndrome, which do not synthesize or very few elastic fibres. A hydrogel formed exclusively of Elactiv’ allowed to access to mechanical properties of the scaffold and to verify its biocompatibility in vitro and its safety and resorption in vivo. Finally, the association of Elactiv' protein to poly(L-lysine) dendrigrafts, highly functionalizable synthetic polymers, enabled to evolve the hydrogel's architecture to a hybrid biomaterial in order to increase its mechanical and biological properties for skin tissue engineering. Taken together, biomimetic and therapeutic potentials of Elactiv' protein make it a promising candidate for soft tissue regeneration

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Tsarouchas, Dimitris. "Fibre network materials : architecture and effective linear elastic properties." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610878.

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36

Noda, Kazuo. "Latent TGF-β binding protein 4 promotes elastic fiber assembly by interacting with fibulin-5." Kyoto University, 2013. http://hdl.handle.net/2433/179349.

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37

Cai, Liang-Wu 1965. "Full-scale simulation of multiple scattering of elastic waves in fiber reinforced composites." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/9573.

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38

Starkey, Carl Alan. "Analysis of the Failure Modes of Twisted Fiber Structures." Marietta College Honors Theses / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=marhonors1210352501.

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39

Saville, Charis Rowan. "Hormonal modulation of ageing skin microstructure and mechanical properties." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/hormonal-modulation-of-ageing-skin-microstructure-and-mechanical-properties(fa635be5-a695-4b7a-989a-43db3868237b).html.

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Ageing tissue is characterised by an alteration in mechanical properties, with tissues becoming increasingly fragile, stiff and less resilient over time. This can lead to a loss of function in tissues which undergo a high degree of stretch and recoil, such as the skin, blood vessels and lungs. These changes are attributed to remodelling of the dermal extra cellular matrix (ECM) proteins which endow tissue with its mechanical properties. Principally the fibrillar collagens provide tensile strength, complemented by the elastic fibres which confer resilience and allow tissues to recoil following deformation. Intriguingly, at the time of menopause, which sees the cessation of the majority of circulating estrogen, skin undergoes accelerated ageing. This strongly suggests a direct link between circulating estrogen and youthful skin. Using an ovariectomised (Ovx) mouse model of human menopause the link between ageing, estrogen deficiency and the dermal ECM proteins was explored. Mechanical testing revealed a significant reduction in the tensile strength, Young’s modulus and stress relaxation time of estrogen deprived tissue, indicating postmenopausal skin would be weaker, more lax and less able to withstand sustained force. Corresponding histological analysis highlighted the elastic fibres are dramatically reduced by estrogen deprivation with seemingly little effects on the fibrillar collagen abundance or alignment. Direct comparison between Ovx and age, reveals age affects mechanical properties in a completely opposing way, with aged tissue higher in tensile strength, Young’s modulus and stress relaxation time compared to control and Ovx. Proteomic analysis by mass spectrometry confirmed elastic fibres to be highly sensitive to estrogen levels. Additionally small leucine rich proteoglycans (SLRP’s) were also significantly reduced by estrogen deficiency, which could affect collagen fibrillogenesis and leave tissue weaker and more susceptible to damage. Despite the opposing effects on mechanical properties, ageing and estrogen deficiency had comparable effects on ECM abundance, suggesting the amount of ECM is not a predictor of mechanical properties; however disparity may be in part due to increased advanced glycation end product crosslinking. Further investigation suggests the mechanism for elastic fibre degradation may be via significant subcutaneous adipose hypertrophy and/or increased gelatinase activity. Both estrogen replacement and stimulation of estrogen receptor α with the agonist 2,3-bis(4-hydroxyphenyl)-propionitrile (PPT) were found to prevent elastic fibre degradation and adipose hypertrophy. Additionally these treatments were also found to induce key elastic fibre proteins in both the mouse model and cultured human dermal fibroblasts. A deeper understanding of estrogen mediated ECM remodelling offers opportunities for targeted pharmacological intervention to slow the effects of menopause and ageing.

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Captain, V. S. "The effect of inextensibility on elastic surface and interfacial waves." Thesis, University of East Anglia, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378895.

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Kondo, Yasuhiro. "Measurement of Σ-p Elastic Scattering Cross Sections with a Scintillating-Fiber Active Target." 京都大学 (Kyoto University), 2000. http://hdl.handle.net/2433/151663.

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Caselman, Elijah. "Elastic property prediction of short fiber composites using a uniform mesh finite element method." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/5036.

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Thesis (M.S.)--University of Missouri-Columbia, 2007.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on March 19, 2008) Includes bibliographical references.

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Middleton, Joseph Ervin. "Elastic property prediction of long fiber composites using a uniform mesh finite element method." Diss., Columbia, Mo. : University of Missouri-Columbia, 2008. http://hdl.handle.net/10355/5684.

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Thesis (M.S.)--University of Missouri-Columbia, 2008.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 13, 2009) Includes bibliographical references.

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Darya, zadeh S., and G. I. Lvov. "A new numerical method for determination of effective elastic constants in a composite with 3D orthogonal nonwoven fibers." Thesis, НТУ "ХПИ", 2015. http://repository.kpi.kharkov.ua/handle/KhPI-Press/25080.

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Walton, Lucy Anne. "From molecules to tissues : characterising the relationship between structure and function in ageing arteries." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/from-molecules-to-tissues-characterising-the-relationship-between-structure-and-function-in-ageing-arteries(b06aab9a-6845-41d2-ac97-0aac85e71e1a).html.

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Increased arterial stiffness is a predictor of cardiovascular events and mortality across a diverse range of populations. Although gross-mechanical stiffness can be measured in vivo, in order to understand the pathological mechanisms it will be necessary to identify which local micro-structural remodelling events are the prime drivers of altered macro-mechanical function. However, characterisation of arterial structure by conventional histological approaches: i) commonly induces artefacts as a consequence of the sectioning process, ii) provides no insight into the three dimensional structure of the tissue and iii) is performed on unpressurised tissue. This project has set out to address these limitations by developing new micro computed x-ray tomography (micro-CT) methodologies which are capable of visualising the three dimensional structure of rat arteries. This new methodology was then been applied in combination with gross-and micro-mechanical testing and atomic force microscopy imaging to characterise the effects of both intra-luminal pressure and age on arterial structure and function. From these investigations it was clear that micro-CT could readily distinguish discrete tissue sub-structures in paraffin embedded tissues, including skin and arteries and that this imaging approach was compatible with complimentary histological and immunohistochemical analyses. Characterisation of the structure and mechanical function of carotid arteries in aged rats demonstrated localised stiffening in the adventitial layer and a change in the molecular structure of adventitial collagen. The effects of intra-luminal pressure on structure using micro-CT revealed changes in artery cross-sectional area, which suggest the artery wall may be compressible. Investigations into the effects of pressure on the molecular structure of adventitial collagen revealed an increase in periodicity at mean pressure. These findings together demonstrate that the adventitial layer has an important role in the development of arterial stiffness. Micro-CT can reveal novel information that improves our understating of artery structure and how artery structure changes during ageing.

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Masri, Haji Mohammad Khairul Ja'afar Awang Haji. "Elastic properties and local buckling of pultruded fibre reinforced plastic profiles." Thesis, Cardiff University, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.548179.

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Boizot, Jérémy. "Modélisation de la plaie chronique : contrôle de la formation de fibres élastiques en conditions hypoxiques." Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10111.

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Doué, Manon. "Rôle de la carbamylation des protéines matricielles dans l’altération des propriétés de la paroi vasculaire : application à l'anévrysme aortique." Thesis, Reims, 2019. http://www.theses.fr/2019REIMS042.

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Les modifications post-traductionnelles non enzymatiques des protéines, telles que la glycation ou la carbamylation, altèrent leurs propriétés structurales et fonctionnelles, et conduisent à leur vieillissement moléculaire. La réaction de carbamylation correspond à la fixation de cyanate, majoritairement dérivé de l'urée, sur les groupements aminés des protéines. Plusieurs études ont démontré un lien entre la carbamylation des protéines et les complications cardiovasculaires. Le but de ce travail était de déterminer comment la carbamylation des protéines matricielles pouvait participer à la modification des propriétés mécaniques de la paroi vasculaire et au développement de l'anévrysme aortique. Nos expériences montrent que les protéines matricielles vasculaires, dont l'élastine, sont carbamylées. Bien que la morphologie des fibres ne soit pas modifiée, l'élastine carbamylée est plus sensible à la dégradation par l'élastase pancréatique. L'augmentation du taux de carbamylation des protéines de la matrice extracellulaire aortique dans un modèle de souris alimentées en cyanate entraîne une rigidité accrue des fibres élastiques, évaluée par microscopie à force atomique, qui se répercute par une augmentation de la vitesse de l’onde de pouls. Par ailleurs, les souris alimentées en cyanate développent moins souvent un anévrysme aortique, et présentent une proportion moins importante d'anévrysmes rompus. Enfin, les protéines carbamylées sont capables de stimuler la migration des cellules musculaires lisses vasculaires et d'induire un stress oxydant. Ces résultats suggèrent que la carbamylation des protéines matricielles participe au remodelage de la paroi vasculaire et conduit à l'altération de ses propriétés mécaniques
Nonenzymatic post-translational modifications of proteins, such as glycation or carbamylation, alter their structural and functional properties, and result in their molecular aging. The carbamylation reaction corresponds to the binding of cyanate, mainly derived from urea, to the amino groups of proteins. Several studies have demonstrated a link between protein carbamylation and cardiovascular complications. The aim of this work was to determine how carbamylation of matrix proteins could participate in the modification of the mechanical properties of the vascular wall and in the development of aortic aneurysm. Our experiments show that vascular matrix proteins, including elastin, are carbamylated. Although fiber morphology is unchanged, carbamylated elastin is more sensitive to pancreatic elastase degradation. The increased carbamylation rate of aortic matrix proteins in a murine model fed with water supplemented with cyanate leads to an increased stiffness of elastic fibers, as evaluated by atomic force microscopy, which is associated with an increase of pulse wave velocity. Cyanate-diet mice have less frequently aortic aneurysms and a smaller proportion of aneurysm ruptures. Finally, in vitro carbamylated proteins are able to stimulate the migration of vascular smooth muscle cells and to induce an oxidative stress. These results suggest that the carbamylation of matrix proteins participates in the remodeling of the vascular wall and leads to the alteration of its mechanical properties

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Mera, S. L. "The composition and integrity of elastic fibres in health and disease : A morphological and histochemical study." Thesis, University of Bristol, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373832.

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Bispo, Rodrigo Freitas Monte. "Efeitos do extrato etanólico da Himatanthus bracteatus e Ocotea longifolia nas fibras elásticas e túnica média da aorta de camundongos C57BL6J em um modelo de aterosclerose experimental." Universidade Federal de Alagoas, 2016. http://www.repositorio.ufal.br/handle/riufal/1772.

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Atherosclerosis accounts for the highest illness and mortality rates throughout the world. This disease begins with the accumulation of cholesterol and the proliferation of smooth muscle cells in the endothelium, which leads to its inflammation as well as the hardening and thickening of arterial walls. The Brazilian Health Ministry issued the National Policy of Integrative and Complementary Practices in the public healthcare system, which encourages phytotherapeutic research and development based on the use of medicinal plants. Studies involving Himatanthus bracteatus have demonstrated action on arachidonic acid in rats as well as analgesic, anti-inflammatory and antimicrobial/antibacterial properties. Evidence of antimicrobial/antibacterial activity has also been found in Ocotea longifolia, with effective COX-1 and COX-2 inhibition. It is therefore important to determine the effect of alcoholic extracts of Himatanthus bracteatus and Ocotea longifolia on the thickness of the tunica media and elastic fibers in the descending portion of the aorta in C57BL6J mice. The aim of the present study was to determine the thickness of the tunica media and percentage of elastic fibers in the descending portion of the aorta of mice in which experimental atherosclerosis was induced. A 42-day experimental animal study was conducted in which C57BL6J mice were submitted to an atherosclerotic diet (1.25% cholesterol, 0.5% cholic acid and 15% fat). Forty-nine mice were divided into seven groups: C group (control –one mL of 0.9% saline solution; n = 7), H group (hyperlipidemic -1.25% cholesterol, 0.5% cholic acid and 15% fat; n = 7), HT25 group (Himatanthus bracteatus [25 mg/mL]; n = 7), HT12.5 group (Himatanthus bracteatus [12.5 mg/mL]; n = 7), OT25 group (Ocotea longifolia [25 mg/mL]; n = 7), OT12.5 (Ocotea longifolia [12.5 mg/mL]; n = 7) and R group (rosuvastatin [0.27 mg/mL]; n = 7). The primary variables were mean thickness of the tunica media and percentage of elastic fibers in the descending portion of the aorta. The secondary variables were total cholesterol, HDL, LDL, triglycerides, body mass, heart mass, blood sugar concentration and expression of the markers TNF-α, CD-68 and isoprostan. Statistical analysis was performed with the aid of the GraphPad Prism program (version 5.0). The data were expressed as mean, standard deviation and standard error. The Kruskal-Wallis test and Dunn’s post hoc test were used for data with non-normal distribution. One-way analysis of variance and Tukey’s post hoc test were used for data with normal distribution. A 95% confidence interval was calculated for each estimated point. The alcoholic extracts of Himatanthus bracteatus and Ocotea longifolia led to a significant reduction in the thickness of the tunica media of the descending portion of the aorta. However, no significant change occurred in the percentage of elastic fibers. The extracts also led to significant reductions in total cholesterol, LDL and triglycerides. Moreover, the immunohistochemical analysis revealed significant changes in the expression of TNF-α, CD-68 and isoprostane.
A aterosclerose é responsável pelo maior índice de morbidade e mortalidade que ocorre no mundo. Esta doença ocorre inicialmente através do acúmulo de colesterol e proliferação de células musculares lisas no endotélio, que leva a sua inflamação, endurecimento e espessamento da parede das artérias. No Brasil, o Ministério da Saúde regulamentou a proposta de Política Nacional de Práticas Integrativas e Complementares no Sistema Único de Saúde, que incentiva a pesquisa e o desenvolvimento de medicamentos fitoterápicos a partir de plantas medicinais. A Himatanthus bracteatus pesquisas mostraram ação no ácido araquidônico em ratos e uma potente atividade analgésica e antiinflamatória e antitumoral, já a Ocotea longifolia foram encontradas evidências de atividade antimibacteriana com eficácia na inibição COX-1, COX-2. Sendo assim é relevante verificar a eficácia dos extratos etanólicos da Himatanthus bracteatus e Ocotea longifolia na espessura da túnica média e nas fibras elásticas na parte descendente da aorta de camundongos C57BL6J. Os objetivos foram verificar a espessura da túnica média e percentual de fibras elásticas da parte descendente da artéria aorta de camundongos induzidos a aterosclerose experimental. Foi um estudo experimental em animais por 42 dias. Os animais foram camundongos C57BL6J, submetidos a dieta aterosclerótica (1,25% de colesterol, 0,5% de ácido cólico e gordura de 15%).Os animais foram divididos em 7 grupos: grupo C (controle 1mL de soro fisiológico 0,9%, n=7), grupo H (hiperlipidêmico 1,25% de colesterol, 0,5% de ácido cólico e gordura de 15%, n=7), grupo HT25 (Himatanthus bracteatus 25mg/mL, n=7), grupo HT12,5 (Himatanthus bracteatus 12,5mg/mL, n=7), grupo OT25 (Ocotea longifolia 25mg/mL, n=7), grupo OT12,5 (Ocotea longifolia 12,5mg/mL, n=7) e grupo R (rosuvastatina 0,27mg/mL, n=7) total de 49 animais. As variáveis primárias foram a média da espessura da tunica média e percentual de fibras elásticas da parte descendente da aorta. Variáveis secundárias foram: colesterol total, HDL, LDL, triglicerídeos, massa corpórea, peso do coração, glicemia, expressão dos marcadores TNF-α, CD-68 e isoprostano. A análise estatística foi realizada usando como ferramenta software GraphPad Prism (versão 5.0), os dados desta análise foram expressos em média, desvio padrão e erro padrão. Para os resultados que não seguiram a distribuição normal foi utilizado o teste de KRUSKAL-WALLIS e o pós-teste DUNNS. Para comparações entre os grupos será utilizado o ANOVA one-way e o pós-teste de TUKEY para os dados que seguem a distribuição normal. Foi calculado o intervalo de confiança de 95% para cada ponto estimado. Os extratos etanólicos da Himatanthus bracteatus e Ocotea longifolia reduziram de forma significante a espessura da túnica média da parte descendente da aorta, contudo não houve diferença significante no percentual de fibras elásticas. Os extratos obtiveram redução significante dos parâmetros sanguíneos: colesterol total, LDL, triglicerídeos e através da análise imunohistoquímica do TNF-α, CD-68 e isoprostano.

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Dissertations / Theses on the topic 'Elastin fibers'

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