The use of intravascular stents to restore blood flow through restricted vessels in patients with coronary artery disease has become the preferred method for treating a variety of lesion locations and pathologies. As new stent configurations and coatings are developed, a great need exists for high-throughput preclinical evaluation techniques that can interface human tissue with three-dimensional devices. Thus, the goals of this dissertation research were 1) to develop an in vitro blood vessel mimic composed of human cells for preclinical evaluation of intravascular devices, and 2) to utilize the mimic to assess neointimal responses to implanted stents.Experiments in support of these goals were broken into four specific aims. The first aim was to develop an in vitro human blood vessel mimic based on techniques for creating tissue engineered vascular grafts. The second aim was to determine the feasibility of utilizing this vessel mimic for bare metal stent evaluation. The third aim was to use the in vitro vessel to evaluate the cellular response to protein-coated stents. The fourth aim was to take advantage of the ability to control the in vitro vessel environment in order to evaluate the effect of shear rate on the neointimal response to implanted stents.Human blood vessel mimics were created by sodding fat-derived microvascular endothelial cells onto expanded polytetrafluoroethylene grafts and cultivating the vessels in bioreactor systems. This resulted in the development of a luminal lining of endothelial cells with sub-endothelial smooth muscle and mesenchymal cells. Deployment and assessment of bare metal stents within blood vessel mimics supported the feasibility of using the model for stent evaluation, and demonstrated that cell coverage of the device surface could be observed and measured. Protein-modified stents were created by submerging devices in enriched medium, and following implantation in the blood vessel mimic exhibited increased cell coverage and increased tissue thickness as compared with bare metal stents. Finally, an increase in shear rate lead to decreased neointimal coverage of implanted bare metal and modified stents. Overall, this dissertation demonstrates that in vitro human blood vessel mimics can be created and utilized for preclinical device evaluation.

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In this thesis we consider two classes of binary matroids, even cycle matroids and even cut matroids. They are a generalization of graphic and cographic matroids respectively. We focus on two main problems for these classes of matroids. We first consider the Isomorphism Problem, that is the relation between two representations of the same matroid. A representation of an even cycle matroid is a pair formed by a graph together with a special set of edges of the graph. Such a pair is called a signed graph. A representation for an even cut matroid is a pair formed by a graph together with a special set of vertices of the graph. Such a pair is called a graft. We show that two signed graphs representing the same even cycle matroid relate to two grafts representing the same even cut matroid. We then present two classes of signed graphs and we solve the Isomorphism Problem for these two classes. We conjecture that any two representations of the same even cycle matroid are either in one of these two classes, or are related by a local modification of a known operation, or form a sporadic example. The second problem we consider is finding the excluded minors for these classes of matroids. A difficulty when looking for excluded minors for these classes arises from the fact that in general the matroids may have an arbitrarily large number of representations. We define degenerate even cycle and even cut matroids. We show that a 3-connected even cycle matroid containing a 3-connected non-degenerate minor has, up to a simple equivalence relation, at most twice as many representations as the minor. We strengthen this result for a particular class of non-degenerate even cycle matroids. We also prove analogous results for even cut matroids.

Thesis (doctoral)--Lund University, 1993. / Added t.p. with thesis statement inserted.

Thesis (M. S.)--Bioengineering, Georgia Institute of Technology, 2010. / Committee Chair: Chaikof, Elliot; Committee Member: Conticello, Vincent; Committee Member: Jo, Hanjoong. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (doctoral)--Lund University, 1993. / Added t.p. with thesis statement inserted.

Made available in DSpace on 2014-10-09T12:54:54Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:07:31Z (GMT). No. of bitstreams: 1 12798.pdf: 1929024 bytes, checksum: c22a6f1976fbfd36f63996f95ebc2302 (MD5) / Dissertacao (Mestrado Profissionalizante em Lasers em Odontologia) / IPEN/D-MPLO / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP; Faculdade de Odontologia, Universidade de Sao Paulo, Sao Paulo

Made available in DSpace on 2014-10-09T12:54:54Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:07:31Z (GMT). No. of bitstreams: 1 12798.pdf: 1929024 bytes, checksum: c22a6f1976fbfd36f63996f95ebc2302 (MD5) / Dissertacao (Mestrado Profissionalizante em Lasers em Odontologia) / IPEN/D-MPLO / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP; Faculdade de Odontologia, Universidade de Sao Paulo, Sao Paulo

Orientador: Renato Mazzonetto / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-13T00:13:29Z (GMT). No. of bitstreams: 1 ChavesNetto_HenriqueDuquedeMiranda_M.pdf: 50043298 bytes, checksum: 5e69f8521d79914d88a950613cc0569c (MD5) Previous issue date: 2009 / Resumo: Os procedimentos cirúrgicos envolvendo a reabilitação da região maxilofacial freqüentemente requerem o uso de enxertos ósseos para a reconstrução de deformidades congênitas ou adquiridas, assim como para correções esqueléticas com finalidade estética. Com o objetivo de evitar a abordagem de áreas doadoras para obtenção de enxerto ósseo, os substitutos ósseos foram desenvolvidos. Visando minimizar a dificuldade de adaptação dos substitutos ósseos na área doadora, os veículos para inserção destes vêm sendo estudados. Para o presente estudo, foram utilizados 8 cães, machos, sem distinção de raça, provenientes do biotério da Unicamp. Após tricotomia e anti-sepsia com polivinilpirrolidona iodo a 10% foram realizados 4 defeitos bicorticais de 8mm de diâmetro na calota craniana de cada animal. O preenchimento das cavidades se deu do seguinte modo: Grupo I - coágulo sangüíneo, Grupo II - osso autógeno particulado, Grupo III - matriz óssea bovina anorgânica, Grupo IV - matriz óssea bovina anorgânica associada a carboxi-metilcelulose. Os períodos de sacrifício foram de 3 e 6 semanas. Através de análise descritiva radiológica e histológica, observou-se no período de 3 semanas a presença de tecido conjuntivo, vasos sangüíneos, material utilizado para preenchimento, assim como as bordas nítidas em todos defeitos. O Grupo II foi o único a apresentar regiões de aposição de novo tecido ósseo. No período de 6 semanas observou-se a presença de tecido conjuntivo, vasos sangüíneos e material utilizado para preenchimento em todos defeitos. O Grupo II foi o único que apresentou as partículas de osso autógeno utilizadas para o preenchimento em estágio de reabsorção avançado sendo também o único a não apresentar as bordas entre o defeito e osso pré-existente nítidas, no período de 6 semanas. Desta forma observou-se que, apesar do enxerto de osso autógeno apresentar melhores resultados em termos de reparação óssea, a matriz óssea bovina anorgânica demonstrou ser biocompatível, servindo como osteocondutor, assim como que o carreador carboxi-metil-celulose influênciou de maneira negativa o processo de reparação óssea. / Abstract: Surgical procedures involving maxillofacial region frequently require bone grafting to reconstruct the congenital or acquired defects, as well to aesthetic. Meaning to avoid the donate areas to obtain grafts, the biomaterials have been developed, especially to minimize the hardiness adaptation of them. This way, several vehicles to insert of these bone substitutes are been studied. To perform the present studied were used 8 dogs, males, without pedigree, from the Unicamp vivarium. After trichotomy and antisepsis with PVPI 10% were performed 4 bicortical defects having 8mm of diameter on the calvarium of each animal. The cavities were filled up thru the following way: Group I - Blood clot, Group II - particulate autogenous bone graft, Group III - anorganic bovine bone matrix, Group IV - anorganic bovine bone matrix associated with a carboxi-metil-celulosis. The sacrifice periods were 3 and 6 weeks. Thru the descriptive radiologic and histological analysis, it was observed on 3 weeks period, presence of connective tissue, blood vessels, material used for fulfillment, as well as periphery of the defects well delimited. The Group II was the only one that presented new bone aposition. On the 6 weeks sacrifice period, it was noted the presence of connective tissue, blood vessels, material used for fulfillment in all defects. The Group II was the only one that showed advanced resorption stage of the bone grafts particles used for fulfillment being, also the only one that showed periphery of the defects without limit, on the 6 weeks period. The present work demonstrated that, despite the autogenous bone grafts lead to the best result in terms of bone defect repair, the anorganic bovine bone matrix demonstrated to be biocompatible, being osteoconductible, as well the carrier carboximetil- celulosis interfered negatively on the bone repair process. / Mestrado / Cirurgia e Traumatologia Buco-Maxilo-Faciais / Mestre em Clínica Odontológica