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1
Wang, Ziyu. "Development of electrospun tropoelastin-polyglycerol sebacate scaffolds for soft tissue engineering applications." Thesis, The University of Sydney, 2022. https://hdl.handle.net/2123/27880.
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Soft tissue damages from disease, trauma, and ageing often have limited regeneration capability, leading to the loss of tissue functions and impacting the quality of life. Repair tissue damage using polymeric materials can alleviate issues such as donor shortage and transplantation rejection associated with undesirable immune responses. This project developed tropoelastin-polyglycerol sebacate (tropelastin-PGS) scaffolds with a spectrum of 3D microstructures, tuneable mechanical properties, controllable degradation profile, and excellent biocompatibility suitable for diverse soft tissue applications. Specifically, we tested their ability to repair vascular and skin tissue through in vitro experiments and animal models.
For vascular repair, tropoelastin-PGS vascular graft was shown to support vascular endothelial cell and smooth muscle cell proliferation and allowed them to express vascular-related functions in vitro. Implanted tropoelastin-PGS vascular graft stayed patent for eight months before sacrifice and harvesting. Histology and immunohistochemistry analysis showed that tropoelastin-PGS graft was completely remodelled into a neoartery with de novo generated extracellular matrix including collagen and organised elastic fibres that mimics the elastic lamellae in the native artery.
For skin repair, the tropoelastin-PGS scaffold accelerated wound healing by modulating the local and systemic immune responses. Locally, tropoelastin-PGS treated wound showed reduced inflammation and recruited more M2 macrophage compared to a commercial product Integra® and PGS control, contributing to enhanced wound healing. Systemically, the addition of tropoelastin reduced the relative spleen size. Through flow cytometry, the spleen of the tropoelastin-PGS group contained fewer granulocytes and monocytes compared to PGS and was shown to have an early and stronger engagement with the lymphoid cells associated with the adaptive immune response.
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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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Hyder, Safeer. "Ultrasound based soft tissue elastic modulus and strain measurement." Thesis, University of Leeds, 2017. http://etheses.whiterose.ac.uk/18279/.
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Conventional B-mode ultrasound provides information on the anatomical features using acoustic impedance differences in the tissues. Ultrasound elastography uses a variety of techniques to map soft tissue elasticity. Tissue stiffness is a novel indicator of the tissue health, as many pathologies can alter the tissue stiffness such as cancer and fibrosis. Accurate and early detection of tissue elasticity can guide towards reliable diagnosis, and prognosis of diseases. The objectives of the research reported in this thesis are to implement strain and shear wave elastography techniques on the locally developed ultrasound systems, along with identifying current challenges in elastography and proposing solutions to develop ultrasound elastography as an accurate, and reliable clinical tool. In the first study, strain elastography was implemented and novel strain estimation quality assessment approach was proposed to discard noisy strain images. The second study proposed a shear wave generation method, called Dual Push Beam (DPB) to address challenges of the current shear wave elastography techniques, such as to reduce data acquisition events and to improve imaging depth. Further, the thesis includes the study which introduced a new angle-aligned shear wave tracking method, which improved displacement estimation quality for shear compounding. Final study designed seven different elastography schemes and investigated variations in elasticity estimation across the image by changing shear waves generation beam parameters such as aperture size and focal depth and its implication for liver fibrosis and breast cancer diagnosis.
4
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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Shankara, Bhanu Fricke Brian A. "Determination of the elastic properties of cardiac tissue using scanning acoustic microscopy." Diss., UMK access, 2006.
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Thesis (M.S.)--School of Computing and Engineering. University of Missouri--Kansas City, 2006.<br>"A thesis in mechanical engineering." Typescript. Advisor: Brian A. Fricke. Vita. Title from "catalog record" of the print edition Description based on contents viewed Jan. 29, 2007. Includes bibliographical references (leaves 69-70). Online version of the print edition.
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Pascoe, Katie Clare, and n/a. "Heritable and early life growth factors affect arterial elastic tissue defect formation." University of Otago. Dunedin School of Medicine, 2006. http://adt.otago.ac.nz./public/adt-NZDU20070306.160709.
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A German pathologist first described defects in the elastic tissues of human arteries over one hundred years ago. Much evidence now supports the involvement of these elastic tissue defects (ETDs) in the initiation and progression of atherosclerosis, although this association is not well accepted. Recent research has determined that the migration of medial smooth muscle cells into the intima (and therefore the start of the atherosclerotic process) is initiated in an attempt to repair these defects and in addition, that there is a correlation between the extent of intimal thickening and the degree of elastic tissue disruption. The Brown Norway (BN) strain appears to have an increased predilection, having a significantly greater incidence of ETDs within the caudal and renal arteries and the abdominal aorta compared with other rat strains. These defects appear morphologically identical to those observed in the arteries of young humans. The purpose of this study was to determine the magnitude of the genetic and environmental components in the formation of these ETDs in the aorta.
Previous studies have demonstrated that the spontaneous formation of elastic tissue defects in the abdominal aorta of the Brown Noway rat is a genetically inherited phenotype, passed from parent to offspring in an autosomal dominant manner. Following crossbreeding of the BN rat with four other strains (two hypertensive and two normotensive) it was determined that, although the inheritance mode of the ETD phenotype followed an autosomal dominant pattern, the expression or penetrance of this phenotype was reduced in F₁ all crossbred groups. Moreover, the early postnatal growth profile of the F₁ pups appeared to be differentially associated with defect formation. To further examine the relationship between aortic ETDs and birthweight, a well-studied model of in utero growth restriction was investigated in the BN rat. On day 18 of a 23-day gestation the uterine arteries were ligated, which resulted in offspring that were 14% smaller than un-operated control pups. This short-term insult resulted in significantly increased numbers of ETDs in growth-restricted animals at 8 weeks of age, an effect that was also observed in 16-week old males. The effect of in utero growth restriction on ETDs in the guinea pig and ApoE knockout mouse was also examined, to determine if ETDs (and subsequent early atherosclerotic events) may be influenced by the exposure to a growth-restricting event in utero. Despite this work leading to the novel characterisation of ETDs in the guinea pig aorta, the growth restricting surgery resulted in poor maternal and pup outcomes, which limited the conclusions that could be drawn from these studies.
Furthermore, microarray techniques were employed to examine changes in aortic gene expression following growth restriction, by comparing amplified mRNA extracts from 8-week old growth restricted BN pup aortas with extracts from a group of average birthweight, un-operated BN pups. In combination, these studies propose both genetic inheritance and the in utero environment regulate elastic tissue defect phenotype, which in turn potentially affects the initiation and progression of early atherosclerosis.
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Aghaei-Ghareh-Bolagh, Behnaz. "Development of elastic biomaterials as high performance candidates for tissue engineering applications." Thesis, The University of Sydney, 2018. http://hdl.handle.net/2123/18789.
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Tropoelastin is an extracellular matrix protein, which polymerises to form elastin in the body. Due to its distinctive structural, mechanical and biological properties, tropoelastin provides a versatile building block for manufacturing biomaterials applicable to tissue engineering. Silk fibroin is a fibrous protein that has been widely used in biomedical applications because of its strength and durability. Hybrid protein polymers comprised of recombinant human tropoelastin and silk fibroin have favourable characteristics as implantable scaffolds in terms of mechanical and biological properties. In this thesis, a new class of elastic biomaterials based on tropoelastin and silk protein mixtures was developed. Tropoelastin and silk proteins were mixed and stabilised using a novel methodology and the fabrication, characterisation and potential applications of two different materials, a biocompatible film and a highly twisted yarn were explored. The fabricated tropoelastin-silk films were considered for potential corneal replacement applications. They performed similarly to the natural cornea in terms of optical clarity, refractive index, glucose permeability and mechanical properties. They showed a remarkable combination of physical properties encompassing flexibility, elasticity and suturability. Furthermore, the films supported both corneal epithelial and endothelial cell growth and function indicating that this new biomaterial may be suitable for corneal tissue regeneration. The fabricated tropoelastin-silk yarns were continuous, uniform, well twisted and strong. The yarns were easy to handle and could be used to fabricate woven meshes. The meshes supported cell growth and proliferation in vitro and were well-tolerated on in vivo implantation. The compatibility of the tropoelastin-silk yarns with textile technology processing methodologies makes them applicable for the manufacturing of a range of 3D materials suitable for tissue engineering applications.
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Dahal, Shataakshi. "Stem Cells Based Elastic Matrix Regeneration for Small Abdominal Aortic Aneurysms (AAAs) Repair." Cleveland State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=csu1599137475237285.
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Dahal, Shataakshi. "Stem Cells Based Elastic Matrix Regeneration for Small Abdominal Aortic Aneurysms (AAAs) Repair." Cleveland State University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=csu1599137475237285.
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Anderson, Courtney Rae. "The Rate of Intramuscular Tissue Temperature Reduction Between Wetted Ice with Elastic Wrap and Game Ready®." Thesis, North Dakota State University, 2020. https://hdl.handle.net/10365/31747.
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In recent years, the Game Ready® unit has become a popular cryotherapy modality to treat musculoskeletal injuries. The purpose of this study was to determine which cryotherapy method, wetted ice bag with elastic wrap or Game Ready®, decreases triceps surae intramuscular tissue temperature the most during a 30-minute treatment. The independent variables were the cryotherapy modalities (Game Ready® and wetted ice with elastic wrap) and time (baseline, 10, 20, and 30 minutes). Twenty patients participated in this study. Wetted ice with elastic wrap decreased tissue temperatures significantly greater than Game Ready® at 20 minutes (P = 0.03), and 30 minutes (P = 0.02). Since wetted ice with elastic wrap produced a greater and faster decline in intramuscular tissue temperature compared to Game Ready® on medium pressure, this cryotherapy modality should be utilized in the immediate care phase of the injury repair process.
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Ling, Yuting. "Elastic characterization of ex vivo human prostate tissue using vibration optical coherence elastography and second harmonic generation microscopy." Thesis, University of Dundee, 2018. https://discovery.dundee.ac.uk/en/studentTheses/4c4f7057-aaf5-43b0-89c9-dc948e2698dc.
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Swaminathan, Ganesh. "Evaluation Of Adult Stem Cell Derived Smooth Muscle Cells For Elastic Matrix Regenerative Repair." University of Akron / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1462209321.
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Jalkanen, Ville. "Tactile sensing of prostate cancer : a resonance sensor method evaluated using human prostate tissue in vitro." Doctoral thesis, Umeå : Department of Applied Physics and Electronics, Umeå Univ, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1445.
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MURALIDHARAN, PRASANNA. "FINITE DEFORMATION BIPHASIC MATERIAL CHARACTERIZATION AND MODELING OF AGAROSE GEL FOR FUNCTIONAL TISSUE ENGINEERING APPLICATIONS." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1148319031.
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Iori, Gianluca. "Micro-FEM models based on micro-CT reconstructions for the in vitro characterization of the elastic properties of trabecular bone tissue." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amslaurea.unibo.it/5422/.
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This master’s thesis describes the research done at the Medical Technology Laboratory (LTM) of the Rizzoli Orthopedic Institute (IOR, Bologna, Italy), which focused on the characterization of the elastic properties of the trabecular bone tissue, starting from october 2012 to present.
The approach uses computed microtomography to characterize the architecture of trabecular bone specimens. With the information obtained from the scanner, specimen-specific models of trabecular bone are generated for the solution
with the Finite Element Method (FEM). Along with the FEM modelling, mechanical tests are performed over the same reconstructed bone portions. From the linear-elastic stage of mechanical tests presented by experimental results, it
is possible to estimate the mechanical properties of the trabecular bone tissue.
After a brief introduction on the biomechanics of the trabecular bone (chapter 1) and on the characterization of the mechanics of its tissue using FEM models (chapter 2), the reliability analysis of an experimental procedure is explained (chapter 3), based on the high-scalable numerical solver ParFE. In chapter 4, the sensitivity analyses on two different parameters for micro-FEM model’s reconstruction are presented.
Once the reliability of the modeling strategy has been shown, a recent layout for experimental test, developed in LTM, is presented (chapter 5). Moreover, the results of the application of the new layout are discussed, with a stress on the difficulties connected to it and observed during the tests. Finally, a prototype experimental layout for the measure of deformations in trabecular bone specimens is presented (chapter 6). This procedure is based on the Digital Image Correlation method and is currently under development in LTM.
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Jobeili, Lara. "Évolution de modèles tridimensionnels de peau reconstruite pour approfondir la connaissance des mécanismes du vieillissement cutané et validation de l’efficacité « anti-âge » du sélénium." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1044/document.
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La peau et son vieillissement sont un enjeu de santé publique. Les modèles expérimentaux disponibles pour l'étude du vieillissement cutané restent perfectibles. Dans ce contexte, nos objectifs étaient simultanément d'utiliser les modèles de peaux reconstruites (PR) développés dans notre laboratoire afin i) de mieux comprendre les mécanismes du vieillissement cutané, ii) de démontrer l'efficacité et le mécanisme d'action du sélénium comme « anti âge » et enfin iii) de les faire évoluer en utilisant le support poreux ou auto-assemblé avec des fibroblastes du même donneur prélevés à des âges différents. Ainsi, le modèle de PR cultivé sur une longue période a montré une surexpression du microARN miR30-a par RT qPCR dans les PR « âgées » avec une altération de la fonction barrière mesurée par la perte insensible en eau et une perturbation de la différenciation terminale (baisse d'expression de la loricrine et de l'involucrine). Avec le même modèle in vitro, nos résultats démontrent que la supplementation en sélénium retarde la sénescence des kératinocytes souches. Cette efficacité passe non pas par un effet antioxydant comme attendu mais par l'activation de leur adhésion à la lame basale, qui participe à les conserver souche et donc à préserver le renouvellement épidermique. Enfin, nous avons eu la chance exceptionnelle de préparer des PR avec des fibroblastes provenant d'un donneur unique prélevé à 36 et 72 ans. Les résultats immunohistologiques montrent que l'âge induit une augmentation de l'expression de l'élastine et de la fibrilline ainsi que leur co-expression. L'augmentation de LTBP1 et aSMA suggère que cette augmentation inattendue est due à une dérégulation de la voie TGF-ß et une différenciation des fibroblastes en myofibroblastes. En conclusion l'utilisation de différents modèles de PR a permis d'explorer les mécanismes conduisant au vieillissement cutané et de démontrer l'efficacité du sélénium comme anti âge<br>Skin and its aging is a public health issue. In vitro skin models available for the study aging remain perfectible. In this context, our objectives were simultaneously to use skin equivalent (SE) developed in our laboratory i) to better understand mechanisms of skin aging, ii) to demonstrate the effectiveness of selenium as “anti-aging” and finally iii) to improve SE using the porous or scaffold free model with fibroblasts from the same donor at different ages. Thus, the model of SE mimicking senescence showed an overexpression of microRNA miR30-a by RT qPCR in old SE with an alteration of the barrier function measured by the transepidermal water loss and a deficiency of epidermal terminal differentiation (decreased expression of loricrin and involucrin). With the same SE model, our results demonstrate that selenium supplementation delays the senescence of keratinocytes stem cells. This effectiveness does not involve antioxidant effect as expected but the activation of their adhesion to the basement membrane, which participates in preserving stemness and epidermal renewal. Finally, we had the opportunity to prepare SE with fibroblasts from a single donor at 36 and 72 years old. The histological results show that age induces an increase in the expression of elastin and fibrillin as well as their co-expression. The increase of LTBP1 and aSMA suggests that this unexpected increase is due to deregulation of the TGF-ß pathway and fibroblasts differentiation into myofibroblasts. In conclusion, the use of different models of SE helps us to explore some mechanisms leading to skin aging and to demonstrate the efficacy of selenium as “anti-aging”
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Sgarbi, Flávia Celina [UNESP]. "Histomorfometria das fibras colágenas e das fibras do sistema elástico da queilite actínica e sua relação com os níveis de atipia." Universidade Estadual Paulista (UNESP), 2006. http://hdl.handle.net/11449/87942.
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sgarbi_fc_me_sjc.pdf: 1257619 bytes, checksum: e8d58cf54222cb30a853c958e6bbefd1 (MD5)<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)<br>A Queilite Actínica (QA) é uma lesão cancerizável, intimamente relacionada com a exposição solar crônica sobre os lábios que pode evoluir para o carcinoma espinocelular. Os achados histológicos de atipia no tecido epitelial são freqüentes, embora subjetivos. A lâmina própria subjacente apresenta uma alteração basofílica acelular e amorfa, conhecida como elastose solar e degeneração basofílica do colágeno. O melhor meio de prevenção é evitar a exposição constante aos raios solares. O objetivo deste trabalho foi estudar histologicamente as fibras do sistema elástico e as fibras colágenas presentes na lâmina própria da QA e correlacionar esses achados com o grau de atipia epitelial. A atipia epitelial foi avaliada através da sua graduação, considerando ausência desta, atipia discreta, moderada e grave. O grau de atipia foi, então, correlacionado com a quantidade de fibras do sistema elástico e com a quantidade de fibras colágenas. Para esse estudo, foram investigados cinqüenta e um casos de QA. De cada caso foram confeccionadas três lâminas para avaliação histológica. Uma lâmina foi corada pela hematoxilina-eosina para avaliação da atipia; outra foi corada pela resorcina-fucsina de Weigert para avaliação das fibras do sistema elástico, e a terceira foi corada pelo tricromo de Mallory para a avaliação das fibras colágenas. Pelo teste de correlação de Pearson, verificou-se que a correlação foi fraca e estatisticamente insignificante para todos os graus de atipia (p> 0,05), porém pelo teste de regressão lógica ordinal, notou-se que houve relação significativa entre a presença de atipia e a quantidade de fibras colágenas(p <0,05). Foi concluído que não houve relação entre a quantidade de fibras do sistema elástico e a quantidade de fibras colágenas.<br>Actinic cheilitis (AC) is a premalignant condition intimately related to chronic exposure of the lips to sun rays, which may progress to spinocellular carcinoma Histological findings of epithelial atypia are frequent but subjective. The underlying lamina propria is characterized by acellular and amorphous basophilic abnormalities, known as solar elastosis, and basophilic collagen degeneration. The best preventive measure is to avoid constant exposure to sun rays. The objective of this study was to histologically correlate the presence of elastic fibers and collagen fibers in the lamina propria of AC. In addition, the presence of epithelial atypia was evaluated and classified as absent, discrete, moderate and severe. The degree of atypia was then correlated with the quantity of elastic and collagen fibers. Fifty-one cases of AC were investigated. For each case, three slides were prepared for histological analysis. One slide was stained with hematoxylin-eosin for the evaluation of atypia, the second was stained with Weigert's resorcin- fuchsin for the assessment of elastic fibers, and the third was stained with Mallory's trichrome for the analysis of collagen fibers. Pearson's correlation test showed a weak and nonsignificant correlation for all degrees of atypica (p > 0.05). However, ordinal logistic regression analysis revealed a significant correlation between the presence of atypia and collagen fibers (p < 0.05). It was concluded that there is not correlate with the presence of elastic fibers and collagen fibers in the lamina propria. The quantity of elastic fibers (degraded and intact) is not related to the degree of atypia and there seems to be a reduction in the quantity of collagen fibers in cases of mild, moderate and severe atypia.
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Sgarbi, Flávia Celina. "Histomorfometria das fibras colágenas e das fibras do sistema elástico da queilite actínica e sua relação com os níveis de atipia /." São José dos Campos : [s.n.], 2006. http://hdl.handle.net/11449/87942.
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Orientador: Ana Sueli Rodrigues Cavalcante<br>Banca: Ana Lia Albinder<br>Banca: Yasmin Rodarte Carvalho<br>Resumo: A Queilite Actínica (QA) é uma lesão cancerizável, intimamente relacionada com a exposição solar crônica sobre os lábios que pode evoluir para o carcinoma espinocelular. Os achados histológicos de atipia no tecido epitelial são freqüentes, embora subjetivos. A lâmina própria subjacente apresenta uma alteração basofílica acelular e amorfa, conhecida como elastose solar e degeneração basofílica do colágeno. O melhor meio de prevenção é evitar a exposição constante aos raios solares. O objetivo deste trabalho foi estudar histologicamente as fibras do sistema elástico e as fibras colágenas presentes na lâmina própria da QA e correlacionar esses achados com o grau de atipia epitelial. A atipia epitelial foi avaliada através da sua graduação, considerando ausência desta, atipia discreta, moderada e grave. O grau de atipia foi, então, correlacionado com a quantidade de fibras do sistema elástico e com a quantidade de fibras colágenas. Para esse estudo, foram investigados cinqüenta e um casos de QA. De cada caso foram confeccionadas três lâminas para avaliação histológica. Uma lâmina foi corada pela hematoxilina-eosina para avaliação da atipia; outra foi corada pela resorcina-fucsina de Weigert para avaliação das fibras do sistema elástico, e a terceira foi corada pelo tricromo de Mallory para a avaliação das fibras colágenas. Pelo teste de correlação de Pearson, verificou-se que a correlação foi fraca e estatisticamente insignificante para todos os graus de atipia (p> 0,05), porém pelo teste de regressão lógica ordinal, notou-se que houve relação significativa entre a presença de atipia e a quantidade de fibras colágenas(p <0,05). Foi concluído que não houve relação entre a quantidade de fibras do sistema elástico e a quantidade de fibras colágenas.<br>Abstract: Actinic cheilitis (AC) is a premalignant condition intimately related to chronic exposure of the lips to sun rays, which may progress to spinocellular carcinoma Histological findings of epithelial atypia are frequent but subjective. The underlying lamina propria is characterized by acellular and amorphous basophilic abnormalities, known as solar elastosis, and basophilic collagen degeneration. The best preventive measure is to avoid constant exposure to sun rays. The objective of this study was to histologically correlate the presence of elastic fibers and collagen fibers in the lamina propria of AC. In addition, the presence of epithelial atypia was evaluated and classified as absent, discrete, moderate and severe. The degree of atypia was then correlated with the quantity of elastic and collagen fibers. Fifty-one cases of AC were investigated. For each case, three slides were prepared for histological analysis. One slide was stained with hematoxylin-eosin for the evaluation of atypia, the second was stained with Weigert's resorcin- fuchsin for the assessment of elastic fibers, and the third was stained with Mallory's trichrome for the analysis of collagen fibers. Pearson's correlation test showed a weak and nonsignificant correlation for all degrees of atypica (p > 0.05). However, ordinal logistic regression analysis revealed a significant correlation between the presence of atypia and collagen fibers (p < 0.05). It was concluded that there is not correlate with the presence of elastic fibers and collagen fibers in the lamina propria. The quantity of elastic fibers (degraded and intact) is not related to the degree of atypia and there seems to be a reduction in the quantity of collagen fibers in cases of mild, moderate and severe atypia.<br>Mestre
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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<br>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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Nita, Luciana Miwa. "Estudo histoquímico e ultra-estrutural da distribuição das fibras da matriz extracelular na prega vocal humana fetal no período perinatal." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/5/5143/tde-29052008-093547/.
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Acredita-se que nos humanos, o ligamento vocal se desenvolva após o nascimento. No entanto, não há consenso na literatura sobre qual a faixa etária de seu aparecimento. Muitos estudos indicam que no neonato, a lâmina própria da prega vocal apresenta-se com algumas fibras esparsas sem uma organização particular. O principal objetivo deste estudo foi obter informação a respeito das fibras colagênicas e do sistema elástico (sob a luz dos conhecimentos atuais sobre a matriz extracelular), na lâmina própria de pregas vocais de fetos no período perinatal. Laringes obtidas por autópsia de fetos entre sete a nove meses foram estudadas através de microscopia de luz e eletrônica de transmissão. Fibras contendo colágeno foram identificadas através do Método da Picrossírius-polarização, fibras do sistema elástico foram descritas utilizando-se o método de Resorcina-fucsina de Weigert após oxidação com oxona. Os resultados histoquímicos coincidem com as observações da microscopia eletrônica, evidenciando populações de fibras de colágeno segregadas em diferentes compartimentos na lâmina própria. Assim, em sua região central as fibras de colágeno se mostraram finas, fracamente birrefringentes de coloração esverdeada, enquanto que as regiões superficiais e profundas apresentaram fibras grossas de colágeno com forte birrefringência de cor vermelho-amarelada, quando estudadas através do método da Picrossírius-polarização. Estas características sugerem que as fibras finas da região central são compostas principalmente por colágeno tipo III, enquanto o colágeno tipo I predomina nas regiões superficial e profunda, em concordância com as observações da literatura relacionada com o estudo da prega vocal de adultos. Assim como o componente colagênico, as fibras do sistema elástico mostraram uma distribuição diferencial ao longo da lâmina própria. Em certo sentido, esta distribuição é complementar àquela das fibras de colágeno: a região central, na qual fibras colagênicas eram escassas e finas, apresentou maior densidade de fibras do sistema elástico, em comparação às regiões superficial e profunda. Assim, a presença de um padrão de distribuição diferencial das fibras da matriz extracelular na prega vocal humana fetal equivalente à descrição clássica do ligamento vocal adulto nos permitiu concluir que o ligamento vocal já está presente ao nascimento. As implicações funcionais destes achados foram discutidas. O conceito corrente de que os estímulos externos, como a fonação, são essenciais para a determinação da estrutura em camadas da lâmina própria, faz com que nossos resultados sejam surpreendentes ao evidenciar a presença de uma distribuição complexa e organizada dos componentes do tecido conjuntivo na lâmina própria de pregas vocais de fetos no período perinatal. A idéia de que a contribuição genética poderia desempenhar um papel importante na organização destas camadas, independentemente do estímulo mecânico, poderia explicar melhor a presença das estruturas observadas já ao nascimento, uma vez que o mecanismo genético pode agir antes de qualquer estímulo mecânico externo, como a fonação.<br>It is currently believed that, in humans, the vocal ligament develops after birth. However, there is no consensus in the literature about the age of its surge. Most papers describe that in the newborn, the lamina propria shows the presence of some sparse fibers without any particular organization. The main purpose of this study was to obtain information regarding collagenous and elastic system fibers (in the light of the current knowledge on extracellular matrix) in the lamina propria of fetal vocal fold. Larynges obtained from autopsy of human fetuses aged seven to nine months were studied by means of light and electron microscopy. Collagen containing fibers were assessed by the Picrosirius-polarization method, elastic system fibers were described using Weigert\'s resorcin-fuchsin with previous oxidation with oxone. The histochemical results coincide with the electron microscope observations in showing collagen populations segregated into different compartments of the lamina propria. Thus, in its central region the collagen shows up as thin, weakly birefringent, greenish fibers while the superficial and deep regions consist of thick collagen fibers which display a strong birefringence of red or yellow color when studied with the aid of the Picrosirius-polarization method. These characteristics strongly suggest that the thin fibers in the central region are composed mainly of type-III collagen, whereas type-I collagen predominates in the superficial and deep regions, in agreement with the observations in the literature pertaining to studies of adult vocal folds. As well as collagen, the elastic system fibers show a differential distribution throughout the lamina propria. This distribution is complementary, in a sense, to that of the collagen fibers: the central region, with thin collagenous fibers, presents the greatest density of elastic system fibers in comparison to the superficial and deep regions. Thus, the presence of a differential distribution of the extracellular matrix fibers in the fetal vocal fold equivalent to the classical description of the adult vocal ligament allowed the conclusion that a vocal ligament is already present in the newborn. The functional implications of the foregoing findings are discussed. Current ideas sustaining that stimuli like phonation are essential to the determination of the layered structure of the lamina propria would make it surprising that a newborn baby could present a complex and organized distribution of connective tissue components as our results show to be the case. The idea that genetic contrivance instead should play a role in the organization of these layers seems to explain better the observed structures once it would act before any mechanical stimulus similar to phonation could take place.
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Patriota, Regia Celli Ribeiro. "Estudo comparativo pré e pós luz intensa pulsada no tratamento do fotoenvelhecimento cutâneo: avaliação clínica, histopatológica e imunoistoquímica." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/5/5133/tde-10092009-115612/.
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Introdução: A luz intensa pulsada(LIP) tem sido muito utilizada no tratamento do fotoenvelhecimento sem completo conhecimento de seu mecanismo de ação. Métodos: Foram acompanhados 26 pacientes apresentando fotoenvelhecimento grau II-III (GLOGAU, 1994), os quais foram submetidas à avaliação clínica , histológica e imunoistoquímica 6 e 12 meses após o término do tratamento com LIP. Foram realizadas cinco sessões com intervalos de trinta dias. Além da quantificação histomorfométrica das fibras colágenas e elásticas na derme, foram avaliados CD1, CD4, CD8 e ICAM-1. Resultados: Após 6 meses houve melhora clínica moderada e intensa em 76,92% dos casos e a nota média de satisfação foi 8,57 correspondendo à melhora moderada. Após 12 meses do término do tratamento observou-se que 51,52% das pacientes apresentaram uma melhora clínica moderada em relação à clínica inicial. Os efeitos colaterais foram eritema (11/26), edema (10/26), ardência (7/26) e crostas (8/26). A quantificação das fibras colágenas mostrou aumento médio de 51,33% proporção média de fibra colágena na derme após 6 meses de tratamento e o aumento em relação a 12 meses do término do tratamento foi 30,17%; as fibras elásticas mostraram aumento de 44,13% após 6 meses e aumento de 143,19% após 12 meses do término do tratamento. Na análise imunoistoquímica não houve alteração de CD1 e CD8. Em relação ao CD4 houve redução significante após 12 meses do término do tratamento. Quanto ao ICAM-1 houve aumento em 6 meses com retorno aos níveis normais após 12 meses do término do tratamento. Conclusão: A melhora clínica observada foi comprovada pelo estudo histopatológico, que mostrou aumento das fibras colágenas e elásticas na derme. Após 12 meses do término do tratamento observou-se discreta redução do aspecto clínico da pele correlacionado ao histopatológico. Poucos efeitos colaterais foram observados, sendo todos reversíveis. Desta forma, a LIP constitui boa opção de tratamento para o fotoenvelhecimento cutâneo, sendo uma técnica não ablativa, segura e eficaz.<br>Introduction: The intense pulsed light has been used in the treatment of photoaging without full knowledge of its mechanism of action. Material and Methods: 26 patients were followed-up presenting photoaging grade II-III (GLOGAU, 1994), who were submitted to clinical evaluation, histological and immunohistochemistry 6 and 12 months after the treatment termination with LIP. Five sessions were made with 30-day intervals. In addition to histomorphometric quantification of collagen and elastic fibers in the dermis, CD1, CD4, CD8 and ICAM-1 were evaluated. Results: After 6 months there were moderate and intense clinical improvement on 76.92% of the cases and the mean score of satisfaction was 8.57 corresponding to moderate improvement. After 12 months of the treatment termination, it was observed that 51.52% of the patients presented a moderate clinical improvement in relation to initial clinic. The side effects were erythema (11/26), edema (10/26), burning (7/26) and crusts (8/26). The quantification of collagen fibers has shown mean increase of 51.33% in the dermis after 6 months of treatment and the increase regarding to 12 months of the treatment termination was of 30.17%; the elastic fibers has shown an increase of 44.13% after 6 months and increase of 143.19% after 12 months of the treatment termination. In the immunohistochemistry analysis there was no alteration of CD1 and CD8. In relation to CD4, there was a significant reduction after 12 months of treatment termination. Regarding the ICAM-1, there was an increase in 6 months with return to normal levels after 12 months of treatment termination. Conclusion: The observed clinical improvement was verified by the histopathologic study, which showed increase in the elastic and collagen fibers in the dermis. After 12 months of treatment termination, it was observed a discrete reduction of clinical aspect of skin correlated to histopathology. A few side effects were observed, being all reversible. Thus, LIP constitutes good option of treatment for skin photoageing, being a non-ablative, safe and effective technique.
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Gemmer, John Alan. "Shape Selection in the Non-Euclidean Model of Elasticity." Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/223311.
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In this dissertation we investigate the behavior of radially symmetric non-Euclidean plates of thickness t with constant negative Gaussian curvature. We present a complete study of these plates using the Föppl-von Kármán and Kirchhoff reduced theories of elasticity. Motivated by experimental results, we focus on deformations with a periodic profile. For the Föppl-von Kármán model, we prove rigorously that minimizers of the elastic energy converge to saddle shaped isometric immersions. In studying this convergence, we prove rigorous upper and lower bounds for the energy that scale like the thickness t squared. Furthermore, for deformation with n-waves we prove that the lower bound scales like nt² while the upper bound scales like n²t². We also investigate the scaling with thickness of boundary layers where the stretching energy is concentrated with decreasing thickness. For the Kichhoff model, we investigate isometric immersions of disks with constant negative curvature into R³, and the minimizers for the bending energy, i.e. the L² norm of the principal curvatures over the class of W^2,2 isometric immersions. We show the existence of smooth immersions of arbitrarily large geodesic balls in H² into R³. In elucidating the connection between these immersions and the nonexistence/ singularity results of Hilbert and Amsler, we obtain a lower bound for the L^∞ norm of the principal curvatures for such smooth isometric immersions. We also construct piecewise smooth isometric immersions that have a periodic profile, are globally W^2,2, and numerically have lower bending energy than their smooth counterparts. The number of periods in these configurations is set by the condition that the principal curvatures of the surface remain finite and grow approximately exponentially with the radius of the disc.
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Sakae, Flavio Akira. "Distribuição das fibras colágenas e do sistema de fibras elásticas na camada superficial da lâmina própria da prega vocal com edema de Reinke." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/5/5143/tde-31102008-173147/.
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A fisiopatologia do edema de Reinke ainda permanece desconhecida e poucos estudos abordam sobre as alterações das proteínas fibrosas, colágeno e elastina, na matriz extracelular da prega vocal com edema de Reinke. Por isso, este estudo foi idealizado para descrever a distribuição das fibras colágenas e do sistema de fibras elásticas do espaço de Reinke com edema de Reinke comparando com a prega vocal normal e com a severidade do edema. Foram obtidas 20 amostras de pregas vocais de indivíduos com edema de Reinke, sendo nove casos com edema de Reinke grau II e 11 casos grau III. Dezessete indivíduos eram do sexo feminino e três do sexo masculino, com idade variando de 47 a 62 anos (55 ± 4,4 anos). Quinze pacientes eram tabagistas e cinco ex-tabagistas, média e desvio padrão de 22 ± 10,7 maço/ano. O tempo de disfonia apresentou média e desvio padrão de 36 ± 16,6 meses. Dez pregas vocais normais de laringes humanas excisadas foram utilizadas como controles. Os métodos da Picrossírius-polarização e da Resorcina-fucsina de Weigert com oxidação prévia pelo oxone 10% foram empregados para visualização das fibras colágenas e do sistema de fibras elásticas, respectivamente. Uma avaliação semiquantitativa foi utilizada para categorizar os resultados histológicos que foram correlacionados com a idade, consumo de cigarro, tempo de disfonia e com a severidade do edema. Evidenciou-se que o arranjo entrelaçado das fibras colágenas semelhante a uma cesta de vime observado em pregas vocais normais estava desestruturado no edema de Reinke. A desestruturação foi caracterizada por um afastamento das fibras, fragmentação, formando áreas esparsas e tomadas por um estroma mixóide de quantidade variável. Todos os casos de edema de Reinke mostraram uma maior preservação do arranjo das fibras colágenas próximo ao epitélio da prega comparada com as fibras da camada mais profunda do espaço de Reinke. O arranjo do sistema de fibras elásticas formado por fibras finas e onduladas paralelas à membrana basal do epitélio e uma rede de fibras mais finas, logo abaixo da membrana basal do epitélio observado em pregas vocais normais estava desestruturado no edema de Reinke. Na avaliação semiquantitativa observou-se que moderada e intensa desestruturação ocorreram em 90% dos casos com relação às fibras colágenas e em todos os casos para o sistema de fibras elásticas. Houve uma correlação estatisticamente significante entre a idade e o grau de desestruturação das fibras colágenas (r=0,47, p=0,037). Houve diferenças estatisticamente significantes entre os edemas grau II e III quanto à desestruturação das fibras colágenas (p=0,007) e quanto à idade (p=0,036). Observamos com este estudo que as alterações nas proteínas fibrosas presentes no edema de Reinke podem contribuir com a deformidade da prega vocal<br>The physiopathological mechanisms underlying Reinkes edema are still unknown and few studies addressed alterations in the fibrillar proteins, collagen and elastin, in extracellular matrix with Reinkes edema. This study was idealized to describe the distribution of collagen fibers and elastic system fibers in Reinkes space with Reinkes edema, comparing with normal vocal fold and with the severity of Reinkes edema. Twenty surgical vocal fold specimens were obtained from patients with Reinkes edema, nine cases presented grade II severity and 11 cases grade III. Seventeen subjects were females and three were males, ranging in age from 47 to 62 years (mean±SD 55 ± 4.4 years). Fifteen patients were smokers and five ex-smokers, mean±SD of 22 ± 10.7 pack-years. The duration of dysphonia ranged from 6 to 60 months (mean of 36 ± 16.6 months). Ten vocal folds from human larynges of nonsmokers cadavers were used as normal controls. The Picrosirius polarization method and the Weigerts resorcin-fuchsin stain after oxidation with 10% aqueous oxone were used for visualization of collagen fibers and the elastic system fibers, respectively. Findings were categorized semiquantitatively and correlated with age, cigarette smoking, duration of dysphonia and Reinkes edema severity. The intertwined network of collagen fibers resembling a wicker-basket found in normal vocal folds was disarranged in Reinkes edema. Disarrangement of collagen fibers was characterized by loosely arranged and fragmented fibers intermixed with varying amounts of myxoid stroma. All cases showed a better preservation of collagen fibers arrangement closer to the epithelium compared to fibers of the deeper of the Reinkes space. The elastic system fibers arrangement formed by a delicate network of thin and undulated fibers arranged in parallel to the epithelial basement membrane and a network of thinner fibers immediately below the basement membrane was disarranged. The semiquantitatively analysis showed that moderate and large areas of disarrangement of collagen fibers were found in 90% of cases and in all cases for elastic fibers. Age was significantly correlated with collagen fiber disarrangement (r=0.47, p=0.037). There was a statistical difference in collagen disarrangement (p = 0,007) and age (p=0,036) between grade II and grade III severity. In our study, the alterations in the fibrillar proteins observed in Reinkes edema may contribute to the vocal fold deformity
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Ramos, Helena Hotz Arroyo. "Estudo histológico dos efeitos agudos de lesão com laser de diodo 980 nm em pregas vocais de coelhos." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/5/5143/tde-09052018-090014/.
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INTRODUÇÃO: A cicatriz em prega vocal que ocorre após injúria constitui causa importante de disfonia. A fonocirurgia ideal é aquela em que a lesão efetivamente removida com o menor dano possível ao tecido adjacente, a fim de reestabelecer a função da prega vocal ao mesmo tempo em que a sua ultraestrutura sua ultraestrutura é preservada. Tanto o bisturi frio quanto lasers em geral são aceitos como instrumentos para fonocirurgia. O laser de diodo tem sido usado no tratamento de doenças laríngeas. Entretanto, não há consenso quanto os parâmetros ideais desse aparelho para tal finalidade. Inexistem trabalhos que mostrem a forma ou a extensão da lesão provocada com laser de diodo em laringe e tampouco as reações histológicas e cicatriciais provocadas por ele. OBJETIVO: O objetivo desta pesquisa é estudar as alterações morfométricas e histopatológicas observadas nas pregas vocais de coelhos, sete dias após a lesão provocada com o laser de diodo, comparando diferentes configurações do dispositivo. MÉTODO: Vinte e um coelhos machos albinos da raça New Zealand foram distribuídos aleatoriamente em três grupos com sete animais por grupo. Foi realizada uma lesão única durante 20 segundos em cada prega vocal com a ponta da fibra em contato superficial com o tecido. Duas frequências de pulso foram comparadas no Grupo I (10Hz versus 1000Hz), diferentes potências no Grupo II (3W versus 5W) e modos de radiação distintos no Grupo III (pulsado versus contínuo). Após sete dias, as laringes foram excisadas e submetidas à coloração com hematoxilina-eosina, além de coloração histoquímica para colágeno e elastina. Foi realizada análise histológica quantitativa e subjetiva. RESULTADOS: o laser de diodo provocou: exocitose de células inflamatórias; edema de mucosa e submucosa; infiltrado celular extenso em torno da úlcera, composto por polimorfonucleares (especialmente eosinófilos), linfócitos e histiócitos; tecido de granulação com a presença de fibroblastos e vasos neoformados e áreas de necrose do tipo coagulativa. A extensão do processo inflamatório e a extensão linear da úlcera apresentaram diferença significativa entre as duas potências, e foi maior com uso do laser ajustado para 5W. A extensão do processo inflamatório, extensão linear da úlcera, profundidade da úlcera e profundidade do processo inflamatório apresentaram diferença significativa entre os dois modos de emissão do laser, isto é, maior no modo contínuo. A densidade das fibras colágenas apresentaram-se elevadas apenas ao uso do laser no modo contínuo, quando comparado ao modo pulsado. Não houve diferença estatística quanto à densidade de fibras elásticas. CONCLUSÃO: O uso do laser de diodo ajustado em potência de 5W ao invés 3W e o uso do modo contínuo ao invés do pulsado são capazes de aumentar significativamente a injúria térmica nas pregas vocais de coelhos<br>INTRODUCTION. Scarring of the vocal folds is a relevant cause of dysphonia after injury. The ideal phonomicrosurgery would be the one that removes the vocal fold disease in order to restore the biomechanical function, while providing minimal disruption to the surrounding vocal fold layered structure. Steel scalpel and laser systems are widely accepted tools for vocal fold surgical procedures. The diode laser technique has been used in the treatment of laryngeal diseases. However, there is great variability among surgeons with regard to the use of the diode laser for laryngeal surgery and the ideal parameters for this procedure remain unclear. No description of the lesion extent or the vocal fold healing after injury with this device have been reported to date. OBJECTIVE: The aim of this research was to study the morphometric and histopathological changes seen in the vocal fold seven days after injury with the diode laser in a rabbit model, comparing different settings of the device. METHODS: Twenty-one male New Zealand white rabbits were randomized into three groups with seven animals per group. A single spot injury during 20 seconds was performed in each vocal fold with the fiber tip in superficially contact with the tissue. Two pulse frequency were compared in group I (10Hz versus 1000Hz), different powers in group II (3W versus 5W) and distinct wave mode of radiation in group III (pulsed versus continuous). After seven days, the larynges were harvested and subjected to H&E staining, histochemical staining for collagen and elastin, with quantitative and subjective histological analysis. RESULTS: the diode laser provoked exocytosis of inflammatory cells; edema of mucosa and submucosa; extensive cell infiltrate around the ulcer with polymorphonuclear cells (especially eosinophils), lymphocytes and histiocytes; granulation tissue with the presence of fibroblasts and neoformed vessels and areas of coagulative necrosis. The extent of the inflammatory infiltrate and the extent of the ablation crater showed to be greater with the 5W power use. The analyzes of extension of the extent of the inflammatory infiltrate, the extent of the ablation crater, the depth of the ablation crater and depth of the inflammatory process presented greater measurements with the continuous mode. The density of collagen fibers was higher when the laser was used in continuous wave mode. There was no statistically significant difference in elastic fiber density. CONCLUSION: Increasing power from 3W to 5W and using continuous wave rather than pulsed wave mode of the diode laser significantly increased the extent of thermal injury in the rabbit vocal folds
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Rosenstrauch, Doreen. "Use of autologous auricular chondrocytes for lining left ventricular assist devices." Doctoral thesis, [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=972610480.
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Vieira-Damiani, Gislaine 1976. "Análise computacional de fibras elásticas e colágenas da aorta humana." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/310249.
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Orientadores: Konradin Metze, Carlos Lenz Cesar<br>Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas<br>Made available in DSpace on 2018-08-21T10:46:07Z (GMT). No. of bitstreams: 1
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Previous issue date: 2012<br>Resumo: A hipertensão arterial sistêmica (HAS) bem como o envelhecimento provoca mudanças na estrutura dos grandes vasos sanguíneos - aorta e seus ramos - propiciando o desenvolvimento de processos degenerativos que são a causa de diversas doenças. O uso de ferramentas fotônicas na aquisição de imagens, associado a recursos matemáticos para a interpretação delas representa um avanço para as análises histopatológicas, pois permitem a visualização e compreensão de pequenas estruturas que antes eram impossíveis de serem observadas. O objetivo desse trabalho foi associar estas duas tecnologias (ferramentas fotônicas e recursos matemáticos) e com isso criar uma metodologia para a análise simultânea de fibras elásticas e colágenas na aorta. Para tanto utilizamos aorta ascendente de 72 pacientes, sendo 22 normotensos, 38 portadores de HAS e 12 aortas de dissecção. As lâminas coradas com hematoxilina eosina foram examinadas no microscópio multifoton, com dois fótons: laser de argônio para fluorescência da eosina, corante de fibras elásticas e Ti:safira para SHG, sinal gerado por moléculas de colágeno. A distribuição e organização das fibras elásticas e colágenas foram analisadas pelas seguintes variáveis: morfometria geométrica, derivadas da matriz de co-ocorrência de Haralick, Transformada de Fourier e fluorescência ótica integrada. Usando estes descritores da textura associados a fractais, observamos que a geração do SHG é dependente não só da presença do colágeno como também do arranjo destas fibras. Observamos ainda que em indivíduos normotensos, quando comparados aos portadores de HAS, ocorre uma diminuição na distribuição do sinal SHG ao longo da espessura da camada média partindo da íntima em sentido à adventícia. Dessa maneira concluímos que os maiores distúrbios das fibras elásticas, nos indivíduos normais ocorrem na transição do terço interno para o médio, enquanto que nos portadores de HAS eles estão distribuídos em toda a espessura da aorta. Além disso, estes estudos nos permitiram verificar que a dissecção da aorta ocorre entre dois reforços de colágeno, uma vez que este fenômeno foi constatado entre dois picos de SHG<br>Abstract: The arterial hypertension as well as aging induces changes in the structure of large blood vessels - aorta and its branches - leading to development of degenerative processes which are the cause of many diseases. The use of photonics tools for image acquisition, associated to mathematical resources for interpretation of them represents an advance in histopathological analysis, because it allows the visualization and understanding of small structures that were impossible to be observed before. The main objective of this study was to associate both technologies (photonics tool and mathematical resources) to create a new methodology to evaluate, simultaneously, elastic and collagen fibers in aorta. For this we've used autopsies of ascending aortas from 72 patients, being 22 samples from normotensives individuals, 38 from HAS patients and 12 aortas from dissection. HE-stained paraffin sections from ascending aortas were analyzed by multifoton microscopy, with 2 types of photons: Two-photon excited fluorescence (TPEF) for elastin and Ti:safira for SHG to analyze collagen fibers. The distribution and organization of elastic and collagen fibers were analyzed by the following variables: geometric morphometric, derived from the co-occurrence matrix of Haralick, Fourier Transform and Fluorescence optics integrated. Using these texture descriptors associated to analysis of fractals, we've observed that SHG generation is not only dependent on the presence of collagen but on the arrangement of these fibers as well. We also observed that in normotensives individuals, if compared to HAS patients, occurs a decrease in the SHG intensity along the medial thickness from intimate in direction to adventitia. Thus we conclude that the major disorders of elastic fibers in normal subjects occur in the transition from the third layer to the middle, while in HAS individuals these disorders are distributed throughout the thickness of the aorta. Furthermore, this study has allowed us to verify that the aortic dissection has occurred between two peaks of SHG, since this phenomenon was observed between two ribs collagen<br>Doutorado<br>Biologia Estrutural, Celular, Molecular e do Desenvolvimento<br>Doutora em Fisiopatologia Médica
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Nejjar, Ibtissam. "Etude morphologique et biochimique du tissu elastique de l'aorte thoracique humaine lors du vieillissement et de l'atherosclerose." Toulouse 3, 1988. http://www.theses.fr/1988TOU30154.
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Tavares, Raquel Aguiar. "Estudo histológico da matriz extracelular do músculo cricofaríngeo em cadáveres de diferentes idades." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/5/5143/tde-24022010-155855/.
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O músculo cricofaríngeo desempenha um importante papel na deglutição. Acredita-se que seu comportamento elástico seja dependente não apenas do componente muscular, mas também do tecido conectivo intramuscular. O objetivo desse estudo foi analisar a presença e a distribuição do colágeno total, colágenos tipo I e III, fibras elásticas, fibronectina e versican no endomísio do músculo cricofaríngeo em cadáveres de diferentes idades. Vinte e sete músculos foram obtidos mediante autópsia de indivíduos de ambos os sexos com idades entre 28 e 92 anos. Foram realizadas colorações histoquímicas, Método Picrossírius e Método Resorcina-fuccina com oxidação prévia pela oxona, e imunoistoquímicas, para colágeno tipo I, tipo III, fibronectina e versican. A medida dos elementos estudados foi feita por meio de um sistema de análise de imagens que incluía um microscópio, conectado a um computador por meio de uma câmera de vídeo. Foi utilizado o software Image pro Plus, versão 4.1. Para cada caso, quinze imagens não sobrepostas de cada coloração no aumento de 400x foram analisadas. A área de marcação positiva dentro do endomísio do músculo cricofaríngeo foi determinada por um padrão de cor específico para cada coloração. A área de cada elemento da matriz extracelular foi expressa como porcentagem da área total do estudada. Os dados foram expressos em medianas e intervalos interquartílicos. A correlação entre idade e os diferentes elementos da matriz extracelular foi realizada por meio da correlação de Spearman. O teste de Mann-Whitney para distribuição não paramétrica foi utilizado para comparar as áreas porcentuais e os indivíduos de diferente sexo. Todos os testes foram realizados pelo software SPPS versão 13.0 e foi admitido um calor de significância com p < 0,05. O colágeno foi o elemento mais abundante dentre os estudados. Encontrou-se fibras elásticas longitudinais à fibra muscular, finas fibras transversais entre as fibras musculares e espessamento as fibras elásticas nos pólos da fibra muscular. Foi encontrada uma grande variação no conteúdo de fibronectina e versican entre os casos. Não foi evidenciada diferença estatisticamente significativa entre os elementos estudados, o sexo e a idade. Os resultados sugerem que a presença e distribuição desses elementos são importantes para a função do músculo cricofaríngeo e para a manutenção da homeostase. A porcentagem de colágeno encontrada é condizente com a característica esfinctérica do músculo e o arranjo de fibras elásticas contribui para o comportamento elástico e a capacidade de rapidamente reassumir a posição tônica após a abertura durante as deglutições. As variações da quantidade de fibronectina e versican, podem ser resultante da susceptibilidade a fatores agressores. A ausência de alterações com a idade pode significar que o músculo não esteja sujeito às mesmas alterações decorrentes da idade que outros músculos esqueléticos<br>The cricopharyngeus muscle is thought to play an important role in swallowing and related activities. Its elastic behavior is likely to depend not only on its muscular components, but also on the intramuscular connective tissue. Our objective is to analyze the presence and distribution of total collagen, type I and III collagen, elastic fibers, fibronectin and versican in cricopharyngeus muscle endomysium in adults of a wide age range. Twenty-seven cricopharyngeus muscles obtained from male and female cadavers (age range, 28-92 years-old) were analyzed with the Picrosirius method, oxidized Weigert resorcin-fuchisin, immunohistochemistry. Quantification of stained areas in the cricopharyngeus endomysium with different techniques was performed by an image analysis system connected to a light microscope. The correlation between age and the density of different extracellular matrix proteins was tested using Spearman test. T-tests for independent samples were used to analyze the influence of gender and smoking habit on the fractional areas of extracellular matrix. Collagens had the highest density among the analyzed components. Elastic fibers surrounded each muscle cell, longitudinal to their long axis, associated to traversing fibers, forming a fiber network embedding muscle cells. There was a wide variation on fibronectin and versican content among cases. There were no statistical significance for analysis made between those components of extracellular matrix and age andgender. Our findings suggest that presence and distribution of these extracellular matrix components are important to cricopharyngeus muscle homeostasis. The elastic fibers arrangement can contribute for the cricopharyngeus muscle elastic behavior and ability to rapidly reassume its tonic position after opening during swallows. Variations in the expression of fibronectin and versican can beresultant of its injury susceptibility. The absence of changes on extracellular components during aging could mean that cricopharyngeus muscle is not susceptible to similar age changes as other skeletal muscles
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Lundström, Jonathan, and Joel Skagersten. "Optimering samt implementering av Harts automatiserade färgningsmetod : Ersättning av Verhoeffs manuella elastinfärgning." Thesis, Jönköping University, HHJ, Avd. för naturvetenskap och biomedicin, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-52932.
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Elastinfibrer ger blodkärl och andra vävnader deras flexibilitet. Elastinfärgning är relevant när man misstänker melanom, temporalis artrit, venös invasion och efter blodkärlsoperationer. Syftet var att med hjälp av olika vävnadstyper optimera och implementera den automatiserad elastinfärgningen enligt Hart, för att ersätta den nuvarande manuella elastinfärgning enligt Verhoeff vid patologilaboratoriet på länssjukhuset Ryhov, Jönköping. Colon, njure, hud samt navelsträng färgades med den automatiska metoden enligt Hart för att hitta optimala inställningar. Vävnader från samma områden färgades med den manuella metoden enligt Verhoeff samt den automatiska metoden enligt Hart för att jämföra dem. Snitten bedömdes av en läkare så allt färgades som det skulle. Optimeringen av Harts metod resulterade i en inkubationstid på tolv minuter samt en optimal färgningsbehandling utan xylen. Resultaten av jämförelsen mellan den automatiska metoden enligt Hart och den manuella metoden enligt Verhoeff visar att den automatiska metoden enligt Hart ger bättre kontrast samt bakgrundsinfärgning. Slutsatsen blev att den automatiska metoden enligt Harts var bättre än den manuella metoden enligt Verhoeff, att i framtida studier studera möjligheten att byta ut läskningen mot till exempel ytterligare ett etanoldop samt att byta ut snitten av navelsträngen mot snitt av lever.<br>Elastic fibres ensure blood vessels and other tissues flexibility. Elastic staining of tissue is relevant when there is suspicion of melanoma, temporalis arteritis, venous invasion and after operations on blood vessels. The aim of the study was with the help of different tissue samples optimize and implement Hart´s elastic staining method as a substitute for Verhoeff’s at pathology lab at county hospital Ryhov, Jönköping. Colon, kidney, skin, and umbilical cord cross section got stained with Hart´s automated elastic staining method to evaluate the optimal staining procedure. Same region of the tissues was stained with Verhoeff´s manual elastic staining method and Hart´s method. All cross section were assessed and compared with the help of a pathologist doctor. Optimization of Hart´s method resulted in an incubation period of twelve minutes and optimal staining procedure without xylene. Result of comparison between Hart´s staining method and Verhoeff´s staining method showed that Hart´s staining method had a better contrast and background. Conclusions of the study was that Hart´s staining method was better than Verhoeff´s staining method, further studies could include research about a substitution of the blotting step with an extra ethanol bath as an example and liver tissue instead of the umbilical cord.
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Patel, Dhaval Pradipkumar. "Novel PEG-elastin copolymer for tissue engineered vascular grafts." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45811.
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The growing incidences of coronary artery bypass graft surgeries have triggered a need to engineer a viable small diameter blood vessel substitute. An ideal tissue engineered vascular graft should mimic the microenvironment of a native blood vessel, while providing the adequate compliance post-implantation. Current vascular graft technologies lack the ability to promote vascular ECM deposition, leading to a compliance mismatch and ultimately, graft failure. Hence, in order to engineer suitable vascular grafts, this thesis describes the synthesis and characterization of novel elastin mimetic peptides, EM-19 and EM-23, capable of promoting vascular ECM deposition within a poly(ethylene glycol) diacrylate (PEG-DA) hydrogel. By combining the material properties of a synthetic and bio-inspired polymer, a suitable microenvironment for cell growth and ECM deposition can be engineered, leading to improved compliance.
As such, characterization of EM-19 and EM-23 was conducted in human vascular smooth muscle cell (SMC) cultures, and the peptides self-assembled with a growing elastic matrix. After grafting the peptides onto the surface of PEG-DA hydrogels, EM-23 increased SMC adhesion by 6000% over PEG-RGDS hydrogels, which have been the gold standard of cell adhesive PEG scaffolds. Moreover, EM-23 grafted surfaces were able to promote elastin deposition that was comparable to tissue cultured polystyrene (TCPS) surface even though TCPS had roughly 4.5 times more SMCs adhered. Once translated to a 3D model, EM-23 also stimulated increased elastin deposition and improved the mechanical strength of the scaffold over time. Moreover, degradation studies suggested that EM-23 may serve as a template that not only promotes ECM deposition, but also allows ECM remodeling over time. The characterization studies in this thesis suggest that this peptide is an extremely promising candidate for improving vascular ECM deposition within a synthetic substrate, and that it may be beneficial to incorporate EM-23 within polymeric scaffolds to engineer compliant vascular grafts.
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Annoni, Raquel. "Composição da matriz extracelular na doença pulmonar obstrutiva crônica." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/5/5144/tde-24052011-132145/.
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A doença pulmonar obstrutiva crônica (DPOC) é caracterizada por inflamação crônica e alterações estruturais que levam a obstrução das pequenas vias aéreas e destruição do parênquima alveolar. A composição da matriz extracelular (MEC) nos pulmões tem um importante papel em prover e sustentar a arquitetura pulmonar. No entanto, não há uma descrição abrangente da composição da matriz extracelular no trato respiratório de indivíduos portadores de DPOC. No presente estudo investigou-se a composição da MEC das vias aéreas grandes (VAG), pequenas (VAP) e do parênquima pulmonar de pacientes com DPOC. Utilizando imunohistoquímica e análise de imagem analisou-se a área fracionada de fibras elásticas, colágenos I, III e IV, versicam, decorina, biglicano, lumicam, fibronectina e tenascina nas VAG, VAP e no parênquima peribrônquico e distal de 26 indivíduos com DPOC e comparou-se à área fracionada nos pulmões de 26 fumantes sem DPOC e 16 indivíduos não fumantes. A área fracionada de fibras elásticas foi significante maior no grupo de fumantes não obstruídos em comparação com os demais grupos, em todos os compartimentos analisados. Houve menor expressão de colágeno I na camada interna das VAG e nas camadas interna, muscular e externa das VAP dos indivíduos com DPOC e na camada externa das VAP dos fumantes não obstruídos quando comparados ao grupo controle. A área fracionada de versicam mostrou-se menor apenas no parênquima distal do grupo DPOC comparado ao grupo controle. O estudo da matriz de glicoproteínas mostrou maior área fracionada de fibronectina nas camadas interna, muscular e externa das VAP dos indivíduos com DPOC comparados aos demais grupos, assim como maior área fracionada de tenascina foi observado na membrana basal das VAG e na camada interna das VAP do grupo DPOC comparados aos controles. Além disso, a composição da MEC correlacionou-se com valores funcionais, como o VEF1 (% predito). A partir desses resultados, concluímos que a DPOC é caracterizada por complexas alterações nas principais proteínas estruturais nas pequenas e grandes vias aéreas. Tais alterações podem contribuir para a lesão tecidual persistente e com a obstrução ao fluxo aéreo observado na DPOC<br>COPD is characterized by chronic inflammation and structural alterations leading to small airway obstruction and to destruction of the lung parenchyma. The extracellular matrix (ECM) composition of the lungs has an important role in determining airway structure. However, there are no comprehensive descriptions of the ECM composition along the respiratory tract in COPD patients. We postulated that the ECM composition in large and small airways and in lung parenchyma of COPD patients differs from that observed in smoking and non-smoking controls. Using immunohistochemistry and image analysis, fractional areas of elastic fibers, type-I, -III and IV collagen, the proteoglycans versican, decorin, biglycan and lumican; fibronectin and tenascin were quantified in the large (LA) and small airways (SA), in peribronchiolar (PP) and distal parenchyma (DP) of 26 COPD patients and compared to 26 smokers without COPD and 16 non-smoking controls. The fractional area of elastic fibers was higher in non-obstructed smokers than in COPD and non-smoking controls subjects, in all lung compartments. Type-I collagen fractional area was lower in the inner layer of LA and in the inner, muscle and outer layer (OL) of SA of COPD patients and in the OL of SA of non-obstructed smokers when compared to non-smoking controls. The versican fractional area was lower in DP of COPD patients than non-smokers. Fibronectin fractional área was higher in the inner, muscle and outer layer of SA of COPD patients compared to non-smokers. Tenascin fractional area was higher in the subepithelial area of LA and inner layer of SA of COPD when compared to non-smoking controls. Furthermore, ECM composition correlated with FEV1% predicted. Architectural alterations due to an altered ECM composition in COPD are likely to contribute to the persistent tissue injury and to the airflow obstruction characteristic of this disease
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Ravi, Swathi. "Recombinant elastin analogues as cell-adhesive matrices for vascular tissue engineering." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/42728.
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Biomimetic materials that recapitulate the complex mechanical and biochemical cues in load-bearing tissues are of significant interest in regenerative medicine and tissue engineering applications. Several investigators have endeavored to not only emulate the mechanical properties of the vasculature, but to also mimic the biologic responsiveness of the blood vessel in creating vascular substitutes. Previous studies in our lab generated the elastin-like protein polymer LysB10, which was designed with the capability of physical and chemical crosslinks, and was shown to display a range of elastomeric properties that more closely matched those of the native artery. While extensive validation of the mechanical properties of elastin-mimetic polymers has demonstrated their functionality in a number of tissue engineering applications, limited cell growth on the surfaces of the polymers has motivated further optimization for biological interaction. Recent biologically-inspired surface strategies have focused on functionalizing material surfaces with extracellular matrix molecules and bioactive motifs in order to encourage integrin-mediated cellular responses that trigger precise intracellular signaling processes, while limiting nonspecific biomaterial interactions. Consequently, this dissertation addresses three approaches to modulating cellular behavior on elastin-mimetic analogs with the goal of promoting vascular wall healing and tissue regeneration: genetic engineering of elastin-like protein polymers (ELPs) with cell-binding domains, biofunctionalization of elastin-like protein polymers via chemoselective ligation of bioactive ligands, and incorporation of matrix protein fibronectin for engineering of cell-seeded multilamellar collagen-reinforced elastin-like constructs.
The synthesis of recombinant elastin-like protein polymers that integrate biologic functions of the extracellular matrix provides a novel design strategy for generating clinically durable vascular substitutes. Ultimately, the synthesis of model protein networks provides new insights into the relationship between molecular architecture, biomimetic ligand presentation, and associated cellular responses at the cell-material interface. Understanding how each of these design parameters affects cell response will contribute significantly to the rational engineering of bioactive materials. Potential applications for polymer blends with enhanced mechanical and biological properties include surface coatings on vascular grafts and stents, as well as composite materials for tissue engineered scaffolds and vascular substitutes.
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Trejo, Miguel. "Theoretical studies of fluid and elastic membranes." Paris 6, 2009. http://www.theses.fr/2009PA066698.
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Cette thèse est consacrée à l'étude théorique des membranes fluides, comme les vésicules lipidiques, et des membranes élastiques comme les tissus vivants. Nous avons utilisé des méthodes alliant calcul variationnel et géométrie différentielle des surfaces pour décrire les divers aspects mécaniques et topologiques de ces objets et leur influence sur leur comportement physique et biologique. Dans une première partie nous avons abordé le problème de la tension de ligne entre deux domaines qui composent une vésicule inhomogène. A partir d'un modèle modifiant la description habituelle de ces membranes, nous avons montré que les variations structurelles de l'épaisseur de la membrane au raccord impliquent l'existence d'un angle de contact effectif et, par conséquent, une augmentation de la tension de ligne. Nous avons aussi discuté le rôle des impuretés qui se localisent autour de cette ligne de contact. Dans une deuxième partie nous avons étudié la croissance des tissus vivants. Pour les objets minces, elle contribue à fixer la géométrie intrinsèque, c'est-à-dire la courbure de Gauss. Nous avons proposé un modèle dynamique permettant de générer des surfaces à courbure de Gauss constante. Ces surfaces ont été comparées à la forme de certaines fleurs. La dernière partie à été consacrée à l'étude expérimentale du confinement d'une feuille élastique cylindrique à l'intérieur d'un objet de géométrie fixée. Nous avons caractérisé les patrons et le diagramme de phase de la force exercée par ces configurations au début de la croissance.
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Beekman, Anneke. "The Next Step For A Collagen-Elastin Dermal Template In Skin Tissue Engineering." Thesis, The University of Sydney, 2019. http://hdl.handle.net/2123/21092.
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Background MatriDerm, a collagen-elastin dermal template, is commonly used in full-thickness wound repair, to promote dermal regeneration and improve scar tissue quality. Due to the non-cross-linked status, it is expected to biodegrade relatively quickly. Cross-linking the collagen-elastin template could potentially enhance its performance. Aim The aim of this study was to investigate the effects of cross-linking on MatriDerm stability, cell interaction, biodegradation and wound contraction using established cell culture and murine models. Method MatriDerm was cross-linked with glutaraldehyde vapour and characterized in comparison with noncross- linked MatriDerm. Surface morphology, in-vitro stability and strength were assessed through scanning electron microscopy, measurement of protein loss, and tensile modulus testing, respectively. Cell-scaffold interaction, cell proliferation and migration was examined using cultured human dermal fibroblasts. The scaffold biodegradation and its impact on wound healing and contraction was studied in a murine model. Results Cross-linked MatriDerm displayed a slight but significant reduction in average pore size, a significant reduction of total protein loss and a 3-fold increase in tensile strength compared to the non-crosslinked template. In-vitro studies observed a significant increase of fibroblast proliferation and migration in cross-linked MatriDerm and reduced scaffold contraction compared to non-cross-linked MatriDerm. In the murine model, non-cross-linked MatriDerm was almost completely biodegraded after 14 days but cross-linked MatriDerm remained intact, demonstrating similar host responses. Conclusion Cross-linked MatriDerm’s durability was enhanced, demonstrated by significant increase in biostability and strength both in-vitro and in-vivo. The extended exposure of cross-linked MatriDerm in a wound could have beneficial effects on scar tissue formation and further its potential as a base for skin tissue engineering.
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Kinikoglu, Fatma Beste. "Tissue engineering of full-thickness human oral mucosa." Thesis, Lyon 1, 2010. http://www.theses.fr/2010LYO10310.
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L’ingénierie de la muqueuse orale humaine (MOH) a pour but le comblement des pertes de substances suite à un traumatisme facial ou à la chirurgie des lésions malignes. Elle a aussi des applications en recherche pour élucider les mécanismes biologiques de la MO et en pharmacotoxicologie comme alternative à l’expérimentation animale. L'objectif de cette thèse était de reconstruire une MOH proche du tissu normal. À cette fin, la faisabilité du concept a d'abord été testée par co-culture de fibroblastes de la lamina propria et de cellules épithéliales de MOH dans le substrat de collagène-chitosan glycosaminoglycane, développé pour la production de peaux reconstruites. La caractérisation de la MOH reconstruite par histologie, immunohistochimie et microscopie électronique à transmission a montré la présence d’une LP équivalente avec un épithélium pluristratifié et non kératinisé très proche du tissu d’origine. Grâce à ce modèle, nous avons ensuite démontré que l’origine des fibroblastes (MO, cornée, peau) influence significativement l’épaisseur et l’ultrastructure de l'épithélium obtenu par culture de cellules épithéliales orales. Enfin, afin d'améliorer les propriétés adhésives du substrat à base collagène, nous avons ajouté au collagène, une élastine-like recombinante (ELR) contenant le tri-peptide d’adhésion cellulaire, RGD, et produit un nouveau substrat bicouche, poreux par lyophilisation et recouvert d’une couche fibreuse par électrofilage. Ces substrats ont été caractérisés par porosimétrie au mercure, microscopie électronique à balayage et essais mécaniques. Nous avons démontré l’effet stimulant de ELR sur la prolifération des fibroblastes et des cellules épithéliales<br>Tissue engineered human oral mucosa has the potential to fill tissue deficits caused by facial trauma or malignant lesion surgery. It can also help elucidate the biology of oral mucosa and serve as an alternative to in vivo testing of oral care products. The aim of this thesis was to construct a tissue engineered full-thickness human oral mucosa closely mimicking the native tissue. To this end, the feasibility of the concept was tested by co-culturing fibroblasts and epithelial cells isolated from normal human oral mucosa biopsies in a collagen-glycosaminoglycan-chitosan scaffold, developed in our laboratory to construct a skin equivalent. An oral mucosal equivalent closely mimicking the native one was obtained and characterized by histology, immunohistochemistry and transmission electron microscopy. Using the same model, the influence of mesenchymal cells on oral epithelial development was investigated by culturing epithelial cells on lamina propria, corneal stroma and dermal equivalents. They were found to significantly influence the thickness and the ultrastructure of the epithelium. Finally, in order to improve the adhesiveness of conventional scaffolds, an elastin-like recombinamer (ELR) containing the cell adhesion tripeptide, RGD, was used in the production of novel bilayer scaffolds employing lyophilization and electrospinning. These scaffolds were characterized by mercury porosimetry, scanning electron microscopy and mechanical testing. In vitro tests revealed positive contribution of ELR on the proliferation of both fibroblasts and epithelial cells. It was thus possible to construct a viable oral mucosa equivalent using the principles of tissue engineering
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Broiles, JoSette Leigh Briggs. "The use of a tissue engineered media equivalent in the study of a novel smooth muscle cell phenotype." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/22652.
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Thesis (Ph. D.)--Mechanical Engineering, Georgia Institute of Technology, 2008.<br>Committee Chair: Nerem, Robert; Committee Member: Chaikof, Elliot; Committee Member: Taylor, W. Robert; Committee Member: Vito, Raymond; Committee Member: Wight, Thomas.
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Rohan, Christian Pierre-Yves. "Etude biomécanique de l’action des Bas Médicaux de Compression sur les parois veineuses du membre inférieur." Thesis, Saint-Etienne, EMSE, 2013. http://www.theses.fr/2013EMSE0721/document.
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La compression élastique est la thérapeutique conservatrice la plus efficace pour la prise en charge de l'insuffisance veineuse et pour le traitement de la maladie veineuse chronique et de ses complications. Malheureusement, en pratique, les objectifs thérapeutiques ne sont pas toujours atteints ce qui souligne le manque de connaissance actuel concernant les mécanismes qui permettent aux Bas Médicaux de Compression (BMC) d'apporter les bienfaits thérapeutiques. Pour apporter des éléments de réponse, une étude numérique de l’action des BMC sur les veines a été réalisée. Dans un premier temps, une nouvelle méthodologie a été développée pour prévoir les pressions transmises aux parois des veines superficielles et pour quantifier la diminution de la pression transmurale et du calibre que la compression engendre. Une étude de sensibilité réalisée à partir du modèle Eléments Finis développé a permis de mettre en évidence les principaux paramètres qui conditionnent l’action des BMC. Il a ensuite été utilisé pour simuler différents scénarios d’application en lien avec la compression en post-sclérothérapie pour répondre à des problématiques industrielles. Dans une deuxième phase de l’étude, une méthode de modélisation numérique de la réponse des veines profondes à la contraction musculaire lors du port d’un BMC a été développée. Une étude de sensibilité a permis d’apporter des éléments de réponse quant à l’influence relative des aponévroses musculaires, de la contraction musculaire et du port d’un BMC. Ces travaux ouvrent des perspectives d’études nouvelles sur le développement d’outils pour permettre aux fabricants de BMC d’adapter le niveau de compression à chaque patient<br>Compression therapy is a highly effective modality for treating venous disorders of the lower leg and is considered as the “gold standard” for non-operative therapy. However the mechanisms by which Medical Compression Stockings (MCS) benefit the control and treatment of venous insufficiency are neither clearly understood nor have they been conclusively demonstrated. In the present study, the biomechanical response of the lower leg veins to elastic compression is modelled in order to address some of the issues relating to the mechanisms by which it achieves its medical function. First, a new methodology has been developed in order to predict the pressure transmitted to the superficial vein wall during external compression and to quantify the resulting variations of transmural pressure and of the vein cross sectional area. A parametric study was performed to study the influence of the model parameters on the response of the vein. The developed model was also used to simulate different scenarii related to the use of elastic compression after sclerotherapy. In a second step, a numerical approach was developed to model the biomechanical response of deep veins to elastic compression. A parametric study was performed to evaluate the relative influence of the muscular aponeurosis, muscular contraction and external compression applied by MCS. The obtained results bring a new insight on MCS mechanical action and its possible benefits. They also open up new perspectives, especially, regarding the development of new tools to assist MCS manufacturers in adapting the level of compression to the location of the deep vein, the morphology of the patient and the severity of the disease
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Mäki, J. (Joni). "Lysyl oxidases:cloning and characterization of the fourth and the fifth human lysyl oxidase isoenzymes, and the consequences of a targeted inactivation of the first described lysyl oxidase isoenzyme in mice." Doctoral thesis, University of Oulu, 2002. http://urn.fi/urn:isbn:9514267397.
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Abstract
Lysyl oxidases (EC 1.4.3.13, protein-lysine 6-oxidases) are extracellular copper enzymes that initiate the cross-linking of collagens and elastin by catalyzing oxidative deamination of the ε-amino group in certain lysine and hydroxylysine residues. The cross-links formed are responsible for the tensile strength of collagen fibers and the unique elastic properties of elastin.
Three human lysyl oxidase isoenzymes, lysyl oxidase (LOX), lysyl oxidase-like protein (LOXL), and lysyl oxidase-like 2 protein (LOXL2), have been identified and characterized so far. Two additional human lysyl oxidase isoenzymes, lysyl oxidase-like 3 (LOXL3) and lysyl oxidase-like 4 (LOXL4), proteins were identified, cloned, and partially characterized in this study. Both polypeptides showed a high degree of overall similarity to each other and to the LOXL2 polypeptide, whereas the two polypeptides showed a significant similarity to LOX and LOXL only in the C-terminal region, which contains all amino acid residues thought to be needed for the catalytic activity of the LOX enzyme. The LOXL3 gene is expressed in several tissues, the highest expression levels being in the placenta, heart, ovary, testis, small intestine, and spleen. The LOXL4 gene is likewise expressed in most human tissues studied, the highest levels being seen in the skeletal muscle, testis, and pancreas. Both polypeptides were shown to be secreted extracellular proteins.
The role of the first described LOX isoenzyme was studied by inactivating its gene in mice. Most Lox-/-
embryos died at the end of gestation, and the few live-born pups were cyanotic and died within a few hours, autopsy revealing large aortic aneurysms. Light microscopy demonstrated structural abnormalities in the aortic walls of Lox-/- embryos, and further analysis by electron microscopy showed highly fragmented elastic fibers, discontinuity in the smooth muscle cell layers, and endothelial cell damage. Doppler ultrasonography of Lox-/- embryos in utero revealed multiple signs of cardiovascular dysfunction, which contributed to the early death of the Lox-/- mice. The results indicate that Lox has an essential role in the development and function of the cardiovascular system and that this role cannot be replaced to any significant extent by other lysyl oxidase isoenzymes.
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Zhao, Xuefeng. "Pointwise identification of elastic properties in nonlinear heterogeneous membranes, and application to soft tissues." Diss., University of Iowa, 2009. https://ir.uiowa.edu/etd/222.
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Identifying the elastic properties of heterogeneous materials has long been a very challenging problem both theoretically and experimentally. When it comes to biological tissues, this task is even more difficult since biological tissues generally exhibit substantial anisotropic behavior. Moreover, identification is often required to be performed in the service condition of living human tissues and organs, i.e., in vivo. Presently, a method capable of performing such tasks is lacking.
The primary goal of this study is to fill this gap by developing a novel experimental method, termed as pointwise identification method (PWIM), for delineating the elastic properties in nonlinear heterogeneous membranes. Fundamentally, the method hinges on a unique feature of membrane equilibrium problems, that is, wall stress can be determined from equilibrium consideration alone (static determinacy). Thanks to the static determinacy, membrane wall stress can be computed numerically by using finite element inverse elastostatics method (FEIEM), and depends minimally on the constitutive model.
In PWIM, an inflation test is conducted for the target membrane with a series of tracking markers, and a series of deformed configurations are recorded by using appropriate motion tracking techniques. Subsequently, the pointwise stress distribution in each deformed configuration can be acquired independently by applying FEIEM, whereas the corresponding strain distribution can be determined from the deformation relative to the reference configuration which contains implicitly the elastic properties of the material. Consequently, the elastic properties at every material point can be extracted by fitting an appropriate constitutive model to the pointwise stress-strain data pairs.
In this work, we have validated the method for nonlinear isotropic and anisotropic materials through numerical simulations on a patient-specific cerebral aneurysm model, developed an experimental system and validated the method experimentally by conducting an inflation test on a rubber balloon, and conducted a test on a rabbit urinary bladder. The situation of the global stress-free configuration being unknown was considered numerically by employing a concept of local stress-free configuration. In this regard, the method holds the promise of identifying in vivo the elastic properties of membrane-like living organs, e.g., cerebral aneurysms, using medical images upon the availability of powerful image registration techniques.
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Kinikoglu, Beste F. "Tissue Engineering Of Full-thickness Human Oral Mucosa." Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612770/index.pdf.
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Tissue engineered human oral mucosa has the potential to fill tissue deficits caused by facial trauma or malignant lesion surgery. It can also help elucidate the biology of oral mucosa and serve as an alternative to in vivo testing of oral care products. The aim of this thesis was to construct a tissue engineered full-thickness human oral mucosa closely mimicking the native tissue. To this end, the feasibility of the concept was tested by co-culturing fibroblasts and epithelial cells isolated from normal human oral mucosa biopsies in a collagen-glycosaminoglycan-chitosan scaffold, developed in our laboratory to construct a skin equivalent. An oral mucosal
equivalent closely mimicking the native one was obtained and characterized by histology, immunohistochemistry and transmission electron microscopy. Using the same model, the influence of mesenchymal cells on oral epithelial development was investigated by culturing epithelial cells on lamina propria, corneal stroma and dermal equivalents. They were found to significantly influence the thickness and the ultrastructure of the epithelium. Finally, in order to improve the adhesiveness of conventional scaffolds, an elastin-like recombinamer (ELR) containing the cell adhesion tripeptide, RGD, was used in the production of novel bilayer scaffolds employing lyophilization and electrospinning. These scaffolds were characterized by
mercury porosimetry, scanning electron microscopy and mechanical testing. In vitro tests revealed positive contribution of ELR on the proliferation of both fibroblasts and epithelial cells. It was thus possible to construct a viable oral mucosa equivalent using the principles of tissue engineering.
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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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Harrington, Christine. "The Prevalence of Pseudoxanthoma Elasticum-like Connective Tissue Changes in an Oral Biopsy Service." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1308062343.
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Silva, Patricia Angeli da. "Efeitos da inibição crônica das óxido nítrico sintases na mecânica de tecido periférico, no recrutamento eosinofílico e no remodelamento da matriz extracelular induzida por inflamação crônica pulmonar." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/5/5160/tde-25032009-140404/.
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INTRODUÇÃO: A importância da resposta mecânica do parênquima pulmonar na fisiopatologia da asma tem sido recentemente reconhecida. O óxido nítrico é um mediador que controla o tônus muscular liso das vias aéreas, porém este efeito no parênquima pulmonar periférico ainda não foi previamente investigado. Nossa hipótese é que a inibição crônica das óxido nítrico sintases por meio do tratamento com L-NAME (falso substrato para todas as óxido nítrico sintases) pode modular a mecânica do parênquima pulmonar, o recrutamento eosinofílico e o remodelamento da matriz extracelular em modelo de inflamação alérgica crônica pulmonar em cobaias. MÉTODOS: Os animais foram expostos a sete inalações com soro fisiológico ou com ovoalbumina em doses crescentes (1~5mg/ml - 4 semanas) e tratadas ou não com L-NAME (60 mg/kg/ por dia /por animal) na água de beber. Setenta e duas horas após a sétima inalação os animais foram anestesiados, exsanguinados e a mecânica oscilatória do parênquima pulmonar foi medida na condição pré e após desafio (0.1%). Utilizando a técnica de morfometria foram avaliadas a densidade de eosinófilos, o número de células nNOS e iNOS positivas, a densidade de actina, das fibras colágenas e das fibras elásticas bem como a proporção de volume de 8-iso-PGF2 no septo alveolar. RESULTADOS: Os animais que foram expostos à ovoalbumina apresentaram um aumento da resistência e da elastância tecidual (resposta basal e após desafio antigênico), na densidade de eosinófilos, no número de células nNOS e iNOS positivas, na densidade de fibras colágenas e de fibras elásticas bem como na expressão de 8-isoPGF2 no septo alveolar comparativamente aos grupos controles (p<0,05). O tratamento com L-NAME em animais expostos à ovoalbumina atenuou todas as respostas de mecânica do tecido pulmonar periférico (p<0, 01), reduziu o número de células nNOS e iNOS positivas (p<0.01), o conteúdo de fibras elásticas (p<0,001) e de 8-iso-PGF2 no septo alveolar (p<0,001). No entanto, este tratamento não afetou o número total de eosinófilos e o conteúdo de fibras colágenas. Este trabalho sugere que o óxido nítrico contribui para a constrição do parênquima pulmonar e para a deposição de fibras elásticas neste modelo. Estes efeitos foram associados à ativação de iNOS e nNOS em células do parênquima distal e aumento na via do estresse oxidativo<br>The importance of lung tissue mechanical responses in asthma pathophysiology has been recently recognized. Although nitric oxide (NO) is a mediator that controls smooth muscle tonus control in the airways, its effects on lung tissue responsiveness has not been previously investigated. We hypothesized that chronic nitric oxide synthase inhibition by L-NAME (false substrate for all nitric oxide synthases) treatment may modulate lung tissue mechanics, eosinophilic recruitment and extracellular matrix remodeling in a model of chronic pulmonary allergic inflammation. Guinea pigs were submitted to seven normal saline or ovalbumin exposures with increasing doses (1~5mg/mL-4weeks) and treated or not with L-NAME in drinking water. Seventy-two hours after the seventh inhalation the animals were anesthetized, exsanguinated, and oscillatory mechanics of lung tissue strips was performed in baseline condition and after ovalbumin challenge (0.1%). Using morphometry, we assessed the density of eosinophils, the number of iNOS and nNOS-positive cells, the density of actin, the collagen and elastic fibers content and the volume proportion of 8-iso-PGF2 in the alveolar septa. Ovalbumin-exposed animals presented an increase in baseline and maximal tissue resistance and elastance responses, eosinophil density, in the number of iNOS and nNOS positive cells, in the amount of collagen and elastic fibers and in the volume proportion of 8-iso-PGF2 in the alveolar septa compared to controls (p<0.05). L-NAME treatment in ovalbumin-exposed animals attenuated all lung tissue mechanical responses (p<0.01), reduced the number of iNOS and nNOS positive cells (p<0.01), elastic fiber content (p<0.001) and 8-isoPGF2 in the alveolar septa (p<0.001). However, this treatment did not affect the total number of eosinophils and collagen deposition. These data suggest that NO contributes to distal lung parenchyma constriction and to elastic fibers deposition in this model. These effects were associated to iNOS and nNOS activation in pulmonary parenchyma and with an increase in oxidative stress pathway activation
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Kurane, Aditee. "Vascular tissue engineering the creation of living, non-thrombogenic, functional blood vessels based on elastin scaffolds /." Connect to this title online, 2008. http://etd.lib.clemson.edu/documents/1239895754/.
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Kumar, Vivek Ashok. "Design and evaluation of scaffolds for arterial grafts using extracellular matrix based materials." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/45869.
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For small diameter (<6 mm) blood vessel replacements, lack of collaterals and vascular disease preclude homografts; while synthetic analogs, ePTFE, expanded polytetrafluoroethylene, and PET, polyethyleneterephathalate, are prone to acute thrombosis and restenosis. It is postulated that the hierarchical assembly of cell populated matrices fabricated from protein analogs provides a new design strategy for generating a structurally viable tissue engineered vascular graft. To this end, synthetic elastin and collagen fiber analogs offer a novel strategy for creating tissue engineered vascular grafts with mechanical and biological properties that match or exceed those of native vessels. This work details techniques developed for the fabrication of prosthetic vascular grafts from a series of extracellular matrix analogs composed of nanofibrous collagen matrices and elastin-mimetic proteins, with and without cells, and subsequent evaluation of their biocompatibility and mechanical properties. The work details the fabrication and mechanical analysis of vascular grafts made from aforementioned protein analogs. Subesequent studies detail seeding and proliferation of rodent mesenchymal stem cells on protein-based composites to recapitulate the media of native vasculature. Finally detailing in vivo biocompatibility and stability of tissue engineered vascular grafts.
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Wintrich, Sahithya. "Elastogenic characterization of rat BM-MSC-derived SMCS towards use in soft Tissue Engineering." Cleveland State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=csu1351784707.
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Berglund, Joseph Delore. "Elastin and viscoelasticity in cell-seeded collagen constructs cultured in virto : implications for tissue-engineered blood vessels." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/11722.
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La, Joie Elaine Naomi. "Tissue welding : studies of pulsed diode laser interaction with ICG stained porcine aorta and elastin-based biomaterial /." Full text open access at:, 1995. http://content.ohsu.edu/u?/etd,249.
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Caforio, Federica. "Mathematical modelling and numerical simulation of elastic wave propagation in soft tissues with application to cardiac elastography." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLX001/document.
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Les objectifs de cette thèse sont la modélisation mathématique et la simulation numérique de l’élastographie impulsionnelle basée sur la force de radiation acoustique (FRA) dans un tissu mou précontraint, et en particulier le myocarde. La première partie du manuscript concerne la modélisation mathématique de la FRA, la propagation d’ondes de cisaillement qui en résulte et la caractérisation de la vitesse des ondes de cisaillement pour une loi de comportement générale du tissu myocardique. Nous montrons aussi des applications pour l’estimation de l’orientation des fibres cardiaques dans le myocarde et l’évaluation de “pathologies synthétiques ”. Une des contributions principales de ce travail est le développement d’un modèle mathématique original de la FRA. En particulier, à partir d’un modèle biomécanique tridimensionnel du coeur, nous obtenons, à travers une approche asymptotique, les équations qui régissent les champs de pression et de cisaillement induits par la FRA. De plus, nous calculons une expression analytique du terme source responsable de la génération des ondes de cisaillement à partir d’une impulsion acoustique en pression. Dans la deuxième partie de la thèse, nous proposons des outils numériques efficaces pour une simulation numérique réaliste d’une expérience d’élastographie impulsionnelle dans un tissu quasi-incompressible, précontraint et fibré. La discrétisation en espace se base sur des éléments finis spectraux d’ordre élevé. Pour la discrétisation en temps, nous proposons une nouvelle méthode adaptée à l’élasticité incompressible. En particulier, seuls les termes correspondant à des vitesses infinies, associés à la contrainte d’incompressibilité, sont traités implicitement, à travers la resolution d’un problème de Poisson à chaque pas de temps de l’algorithme. En outre, nous proposons une nouvelle méthode d’ordre élevé et efficace pour la résolution d’un problème de Poisson, qui se base sur la transformée de Fourier discrète<br>This PhD thesis concerns the mathematical modelling and numerical simulation of impulsive Acoustic Radiation Force (ARF)-driven Shear Wave Elastography (SWE) imaging in a prestressed soft tissue, with a specific reference to the cardiac setting. The first part of the manuscript deals with the mathematical modelling of the ARF, the resulting shear wave propagation, and the characterisation of the shear wave velocity in a general constitutive law for the myocardial tissue. We also show some applications to the extraction of fibre orientation in the myocardium and the detection of “synthetic pathologies”. One of the main contributions of this work is the derivation of an original mathematical model of the ARF. In more detail, starting from an accurate biomechanical model of the heart, and based on asymptotic analysis, we infer the governing equation of the pressure and the shear wave field remotely induced by the ARF, and we compute an analytical expression of the source term responsible for the generation of shear waves from an acoustic pressure pulse. In the second part of the PhD thesis, we propose efficient numerical tools for a realistic numerical simulation of an SWE experiment in a nearly-incompressible, pre-stressed, fibered soft tissue. The spatial discretisation is based on high-order Spectral Finite Elements (HO-SEM). Concerning the time discretisation, we propose a novel method adapted to incompressible elasticity. In particular, only the terms travelling at infinite velocity, associated with the incompressibility constraint, are treated implicitly by solving a scalar Poisson problem at each time step of the algorithm. Furthermore, we provide a novel matrix-free, high-order, fast method to solve the Poisson problem, based on the use of the Discrete Fourier Transform
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Frauziols, Fanny. "Elastographie ultrasonore des tissus mous du membre inférieur en vue de la caractérisation des effets mécaniques de dispositifs médicaux textiles." Thesis, Saint-Etienne, EMSE, 2015. http://www.theses.fr/2015EMSE0809/document.
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La compression élastique de la jambe est le traitement de référence des pathologies liées à l’insuffisance veineuse. Bien que l’efficacité ne soit plus à prouver, les objectifs thérapeutiques restent non atteints pour certains patients. Un objectif de la compression élastique est la réduction de la pression pariétale des veines afin de rétablir ou d’augmenter le retour du sang vers le cœur par une transmission de pression au travers des tissus mous. Ce mécanisme est complexe et peut être prédit par des modèles éléments finis personnalisés. Pour être personnalisés, ces modèles doivent prendre en compte la géométrie et la carte des propriétés mécaniques du sujet.Dans cette étude, on développe deux méthodologies permettant d’identifier les propriétés mécaniques des tissus mous. Dans un premier temps, on mesure par élastographie ultrasonore par onde de cisaillement la distribution du module élastique au sein des tissus mous superficiels. Dans un deuxième temps, on identifie par une méthode inverse les propriétés mécaniques des tissus mous profonds. Cette méthode associe l’acquisition de données d’un essai expérimental de compression localisée de la jambe à un modèle éléments finis bidimensionnel. Ces deux méthodologies nous permettent d’évaluer l’hétérogénéité des propriétés mécaniques de la peau au fascia cruris et de caractériser le comportement non-linéaire des tissus mous profonds. Enfin, les résultats de ces deux méthodologies sont couplés afin de générer un modèle biomécanique de la jambe sous compression élastique pour prédire la distribution de pression au sein des tissus mous pour quatre sujets sains<br>Elastic compression of the leg is a widely used treatment in case of pathologies related to venous insufficiency. Its benefits are not to be proven, but still, for some patients, the therapeutic goal is not reached. One goal of this treatment is to reduce transmural pressure applied to veins in order to restore or increase blood return to the heart by the transmission of the external pressure through soft tissues. This is a complex mechanism that can be predicted by patient-specific finite element models. To be patient-specific, these models must take into account the geometry and the distribution of mechanical properties of each subject.In this study, two methodologies are developed to identify the mechanical properties of soft tissues. First, the elastic modulus distribution inside the superficial soft tissues is measured by shear wave ultrasound elastography. Second, the mechanical properties of deep soft tissues are identified through an inverse method combining the data acquired from an experimental localized compression of the leg to a bi-dimensional finite element model.These two methodologies allow to evaluate the mechanical properties heterogeneity from the skin to the fascia cruris and to characterize the non-linear behaviour of deep soft tissues. Finally, the results from both methodologies are brought together to generate a biomechanical model of the leg under elastic compression to predict pressure distribution inside soft tissues for four healthy subjects