Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2006. / Tolbert, Laren, Committee Member ; Perahia, Dorva, Committee Member ; Perry, Joseph, Committee Member ; Collard, David, Committee Member ; Bunz, Uwe, Committee Chair.

Thesis (MSc)--University of Stellenbosch, 2006. / Bibliography. Also available via the Internet.

Submitted by MATHEUS TEIXEIRA SEIXAS E SILVA null (matheus.seixas88@gmail.com) on 2018-03-28T11:31:25Z No. of bitstreams: 1 Dissertação_Matheus_Teixeira_Seixas_e_Silva.pdf: 1385952 bytes, checksum: 8a9088d80a7f169efa4152e160a01d47 (MD5) / Approved for entry into archive by Alexandra Maria Donadon Lusser Segali null (alexmar@fcav.unesp.br) on 2018-03-28T13:19:40Z (GMT) No. of bitstreams: 1 silva_mts_me_jabo.pdf: 1385952 bytes, checksum: 8a9088d80a7f169efa4152e160a01d47 (MD5) / Made available in DSpace on 2018-03-28T13:19:40Z (GMT). No. of bitstreams: 1 silva_mts_me_jabo.pdf: 1385952 bytes, checksum: 8a9088d80a7f169efa4152e160a01d47 (MD5) Previous issue date: 2018-03-09 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / As falhas ósseas, principalmente as críticas, representam entidade à parte. Para que se possa gerar reconstituição de falhas ósseas críticas é necessário o auxílio de métodos de enxertia que promovam osteoindução e osteocondução. É frequente a busca de substitutos ósseos de forma a aprimorar técnicas já existentes que promovam osteogênese visando o rápido restabelecimento de suas funções. O enxerto autógeno isolado pode ser insuficiente nas falhas ósseas críticas apesar de ser a melhor opção, causa maior morbidade na recuperação do paciente. O omento tem sido frequentemente estudado na cirurgia devido suas diversas propriedades vasculares vantajosas em locais pouco vascularizados, melhorando a cicatrização e controle de infecção. Este estudo teve como objetivo avaliar a capacidade angiogênica e osteoindutora de fragmentos ósseos xenógenos autoclavados implantados, com ou sem a presença de omento no espaço subcutâneo (S1), espaço subcutâneo juntamente com o omento (S2) e região intraóssea (S3) em coelhos. Utilizou-se 30 animais em um único grupo onde cada animal recebeu os fragmentos ósseos em três sítios corpóreos diferentes (S1, S2 e S3) e foram avaliados por métodos histológicos sua atividade angiogênica e osteogênica. Diante dos resultados obtidos foi possível observar que, o material implantado foi rejeitado devido à reação de corpo estranho ter sido intensa e persistente por todos os tempos (7, 15, 30, 45, 60 dias) de avaliação em todos os locais de implantação. Não houve osteogênese em nenhum dos locais de implantação. Foi possível comparar a angiogênese entre locais de implantação avaliando a infiltração vascular no interior dos fragmentos ósseos, onde S2 apresentou melhores resultados, com início de infiltração vascular aos 7 dias, enquanto que os demais grupos se iniciaram aos 30 dias. Conclui-se com este estudo que diante desta metodologia de preparo de implante ósseo xenógeno, provavelmente não houve remoção completa da antigenicidade, nem mesmo a preservação das BMPs, mas foi possível afirmar que o contato com o omento foi capaz de aumentar a angiogênese nos fragmentos implantados em comparação com os demais locais. / Bone failures, especially criticism, represent a separate entity. In order to generate reconstitution of critical bone defects it is necessary to use grafting methods that promote osteoinduction and osteoconduction. The search for bone substitutes is frequent in order to improve existing grafting techniques for the rapid restoration of their functions. The isolated autogenous graft may be insufficient in the critical bone faults although it is the best option, it causes greater morbidity in the recovery of the patient. The omentum has frequently been studied in the surgery due to its several advantageous vascular properties in places little vascularized, improving the cicatrization and control of infection. The purpose of this study was to evaluate the angiogenic and osteoinductive capacity of implanted autogenous xenogene bone fragments, with or without the presence of omentum in the subcutaneous space (S1), subcutaneous space together with the omentum (S2) and intraosseous region (S3). Thirty animals were used in a single group where each animal received the bone fragments at three different body sites (S1, S2 and S3) and their angiogenic and osteogenic activity were assessed by histological methods. In view of the results obtained, it was possible to observe that the implanted material was rejected because the foreign body reaction was intense and persistent at all times (7, 15, 30, 45, 60 days) of evaluation at all implantation sites. There was no osteogenesis at any of the implantation sites. It was possible to compare the angiogenesis between implantation sites by evaluating the vascular infiltration within the bone fragments, where S2 presented better results, with vascular infiltration beginning at 7 days, while the other groups started at 30 days. It was concluded from this study that in view of this xenogen graft preparation methodology, there was probably no complete removal of the antigenicity, not even the preservation of the BMPs, but it was possible to affirm that the contact with the omentum was able to increase the angiogenesis in the fragments in comparison with the other sites. / 148731/2016-3

A instalação de implantes odontológicos requer a presença de substrato ósseo adequado para garantir estabilidade e equilíbrio biomecânico. A deficiência óssea requer procedimentos de enxertia para adequar o volume para a instalação de implantes, porém a utilização de enxertos autógenos causa aumento de morbidade ao paciente e o uso de material homógeno e xenógeno apresenta dúvidas quanto à reação autoimune, transmissão de doenças e ao grau de reabsorção do enxerto. Com o grande desenvolvimento científico e tecnológico dos biomateriais, os materiais cerâmicos, tornaram-se alternativas promissoras para a recomposição da estrutura óssea perdida. As cerâmicas à base de fosfato de cálcio como a hidroxiapatita (HA) e o beta- fosfato tricálcido (beta-TCP), são materiais que apresentam qualidades desejáveis no processo de neoformação óssea como, por exemplo, a biocompatibilidade, bioatividade e osteocondutividade. A proposta deste trabalho é desenvolver e estudar corpos de prova na forma de cúpula oca de hidroxiapatita preenchidos por coágulo, beta- TCP e composto vitamínico, para estudar a osteogênese supracortical, a partir do potencial osteocondutor da cúpula de HA. As cúpulas foram obtidas por prensagem isostática a 200 MPa e sinterização ao ar a 1100°C por 60 minutos. As caracterizações físico-químicas das matérias-primas e da cúpula de HA foram realizadas por difração de raios X, microscopia eletrônica de varredura e determinação da densidade. Na caracterização biológica, foram realizados o teste de citotoxicidade in vitro e ensaio in vivo. Foram designados 9 coelhos (raça Nova Zelândia), sendo instaladas 18 cúpulas, divididas em três grupos, de acordo com o preenchimento: controle, composto vitamínico e β-TCP em forma de pó. O período de reparação tecidual foi de 8 semanas, no qual foram aplicados marcadores de fluorescência. Após o período de cicatrização e eutanásia, as amostras foram incluídas em resina para a obtenção das lâminas e observadas em microscópio de fluorescência, para avaliar a quantidade de tecido ósseo neoformado, em microscópio de campo claro, para verificar as células presentes no tecido formado e por Espectroscopia de Energia Dispersiva, para análise química, da formação no interior das cúpulas. Como resultados, a cúpula de hidroxiapatita apresenta bom desempenho como arcabouço para neoformação óssea acima da cortical da tíbia de coelhos, pois manteve-se íntegra, com boa estabilidade e boa integração ao tecido ósseo, e principalmente pela neoformação óssea, demonstrando seu potencial osteocondutor. Em relação aos materiais de preenchimento, o beta-TCP apresenta maior valor de área de osso neoformado, em comparação com o coágulo. Nas cúpulas com preenchimento de composto vitamínico, não há formação de tecido ósseo pela não reabsorção do material. / The installation of dental implants requires the presence of adequate bone substrate to ensure stability and biomechanical balance. Deficiency requires bone grafting procedures to adjust the volume for implant placement, but the use of autogenous grafts cause increased morbidity to the patient and the use of homogenous and xenogenous materials has doubts about the autoimmune reaction, transmission of disease and the degree of resorption of the graft. With the great scientific and technological development of biomaterials, ceramic materials, have become promising alternatives for restoration of lost bone structure. The ceramics based on calcium phosphate such as hydroxyapatite (HA) and beta-tricalcium phosphate (beta-TCP) are materials having desirable qualities in the process of bone formation, for example, biocompatibility, bioactivity and osteoconductivity. The purpose of this work is to develop and study the dome-shaped hydroxyapatite filled with blood clot, beta-TCP and vitamin compound, to study osteogenesis supracortical from the osteoconductive potential of the dome of HA. The domes were obtained by isostatic pressing at 200 MPa and sintered in air at 1100 ° C for 60 minutes. The physico-chemical characterization of raw materials and the dome of HA were performed by X-ray diffraction, scanning electron microscopy and density determination. In biological characterization were performed tests for in vitro cytotoxicity and tests in vivo. Were designated 9 rabbits (New Zeland), and installed 18 domes, divided into three groups, according to the filling: control, vitamin compound and β-TCP in powder form. The period of wound healing was 8 weeks, when a fluorescence marker was applied. After the healing period and euthanasia, the samples were embedded in resin to obtain the slides and observed under fluorescence microscope to evaluate the amount of newly formed bone tissue in bright field microscope to check the cells present in the tissue and by Energy Dispersive Spectroscopy for chemical analysis, inside the domes. As a result, the hydroxyapatite dome has good performance as scaffold for bone formation above the cortical tibia of rabbits, it remained intact, with good stability and good integration with bone tissue, especially bone formation, demonstrating osteoconductive potential. Regarding the filling materials, beta-TCP has a higher value of area of new bone formation compared to the clot. In the domes-filled vitamin compound, there is no formation of bone resorption by not material.

Introduction: There is an increasing number of Canadians living with end stage renal disease (ESRD). Kidney transplantation is currently the best treatment for ESRD but long-term outcomes remain suboptimal. Identifying factors associated with better outcomes may lead to interventions or practice change that could improve patient survival or quality of life. The objectives of this thesis were to: i) systematically review the literature to examine centre variation in kidney transplantation outcomes and identify centre and provider level factors that may contribute to variation in outcomes; ii) describe differences that may exist at the patient, centre and provider level at the time of kidney transplantation across the six transplant centres in Ontario, Canada; iii) examine variation in graft and patient survival rates across transplant centres in Ontario; and iv) examine whether patient, centre and provider level characteristics contribute to variation in graft and survival rates across transplant centres. Methods: The first objective of this thesis was met by conducting a systematic review of the literature according to a predefined protocol. The last three objectives of the thesis were met by conducting a population based retrospective cohort study using administrative data from Ontario. Differences at the patient, centre and provider level were described at the time of kidney transplantation. Outcomes of interest included total graft loss; graft loss with follow-up censored at death; death with graft function; and total mortality. All outcomes were assessed at one year post transplantation and at the end of study follow up. Cox proportional hazards regression was used to obtain hazard ratios (HR) for each centre relative to the average across all centres. The independent effect of centre volume and provider characteristics on outcomes was also examined. Results: The systematic review identified 24 eligible studies. Outcomes included graft survival (n=24) and patient survival (n=9). The main characteristics evaluated were centre volume (n=17) and provider volume (n=2). Centre variation in graft survival was described in 80% (12/15) of studies, while less than half of studies (8/17) found a significant association between volume and graft survival. The population based retrospective cohort included 5092 adults (≥18 years) who received a primary solitary kidney transplant across 6 transplant centres in Ontario between January 1st 2000 and December 31st 2013. Variation in patient, centre and provider level factors existed across centres at the time of transplantation. At the end of study follow-up, case-mix adjusted HRs for total graft loss ranged from 0.84 (95% CI 0.53-1.33) to 1.16 (95% CI 1.00-1.34) across centres (p-value for between centre variation 0.46). After adjusting for centre and provider factors, differences across centres persisted. Centre volume, provider experience and provider type were not independently associated with either short or long-term outcomes (all p>0.05) with the exception of graft loss with follow-up censored at death. Discussion: This thesis suggests that there is variation in clinical outcomes across transplant centres in Ontario which is not explained by patient factors, centre volume or provider characteristics at the time of transplantation. Additionally centre volume, provider type and experience were not independently associated with outcomes. Future prospective studies with a larger sample size of transplant centres that examine follow-up care after discharge from hospital (e.g. frequency of visits) are required to better understand this phenomenon.

BACKGROUND: Graft versus host disease (GVHD) is a significant cause of morbidity and mortality following stem cell transplantation. Donor T cells are thought to be the main mediators of this disease, although we have recently identified that host T cells are present and active during acute GVHD suggesting contributions from both donor and host T cells. Whether both donor and host T cells can survive GVHD and coexist harmoniously after disease resolves is unknown. OBJECTIVE: The goals of this thesis are two-fold: (i) to study T cell chimerism in post-GVHD skin and (ii) to understand what effect, if any, treatment has on T cell chimerism in skin. METHODS: Acute GVHD and post-GVHD skin samples were obtained from male patients that had been transplanted with female donor cells. Chimerism was assessed using fluorescence in situ hybridization for the X and Y chromosomes concurrently with immunofluorescence staining for CD3, a T cell marker. Regulatory T cells were stained by immunofluorescence for CD3, CD4 and Foxp3. Medical record data was collected for all patients. RESULTS: We found that the percent of host T cells decreased significantly after resolution of acute skin GVHD compared to during active acute skin GVHD in skin samples obtained from five male patients that had been transplanted with female donor cells. The T cell composition in these patients in post-GVHD skin was primarily donor. We identified chimerism shifted toward donor T cells in patients treated with systemic steroids and this correlated with an increased number of donor T cells infiltrating into skin rather than a decrease in the number of host T cells in skin. With regard to frequency of Tregs, there was no significant difference between the group that had been treated with systemic steroids prior to biopsy and the group that had not. CONCLUSIONS: We discovered that donor chimerism predominates in post-GVHD skin and in active skin GVHD of patients who received systemic steroids, suggesting a role of donor cells in acute GVHD resolution. We were not able to identify a higher frequency of regulatory T cells in the treatment group. It is possible that the Treg recruited to skin by steroid treatment is Foxp3 negative, and therefore missed by our staining approach. The use of another marker is required for future studies.

Indiana University-Purdue University Indianapolis (IUPUI) / Acute graft-versus-host disease (aGVHD) hinders the efficacy of allogeneic hematopoietic cell transplantation (HCT). Plasma levels of soluble serum stimulation-2 (sST2) are elevated during human and murine aGVHD and are correlated to a type 1 T cell response. Membrane-bound ST2 (ST2) on donor T cells has been shown to be protective against aGVHD. ST2 signals through the adapter protein myeloid differentiation primary response 88 (MyD88). The role of MyD88 signaling in donor T cells during aGVHD remains unknown. We found that knocking out MyD88 in the donor T cells protected against aGVHD independent of interleukin 1 receptor (IL-1R) and toll-like receptor 4 (TLR4) signaling, both of which also signal through MyD88, in two murine HCT models. This protection was entirely driven by MyD88-/- CD4 T cells, leading to a decreased type 1 response without affecting T cell proliferation, apoptosis, or migration. In our aGVHD models, loss of intrinsic MyD88 signaling is not responsible for the observed protection. However, transplanting donor MyD88-/- T conventional cells (Tcons) with wild type (WT) or MyD88-/- T regulatory cells (Tregs) ameliorated aGVHD severity and lowered aGVHD mortality. Transcriptome analysis of sorted MyD88-/- CD4 T cells from the intestine ten days post-HCT showed lower levels of Il1rl1 (gene of ST2), Ifng, Csf2, Stat5, and Jak2, among others. Decreased sST2 was confirmed at the protein level with less secretion of sST2 and more expression of ST2 compared to WT T cells. Transplanting donor ST2-/- Tcons with WT or ST2-/- Tregs mirrored observations when using donor MyD88-/- Tcons. This suggests that Treg suppression from lack of MyD88 signaling in Tcons during alloreactivity uses the ST2 but not the IL-1R or TLR4 pathways. The results of our study confirm that ST2 represents an aGVHD therapeutic target that spares Treg function.

No description available.

<p> Water soluble polymers are used as flocculants in wastewater treatment, mineral processing, and pulp and paper production. The work in this thesis focuses on the synthesis of graft polyelectrolytes and the efficiency of the copolymers in flocculation. It was proposed that it would be advantageous to have clusters of high charge that can adsorb strongly to the particle surface, and a long chain of nonionic polymer to bridge the particles together.</p> <p> Electrolyte copolymers were produced using a high molecular weight polyacrylamide as the backbone polymer and a redox agent, ceric ammonium nitrate, to form a radical site on the polymer. DADMAC monomer was polymerized from these radical sites producing grafts of cationic charge. The copolymers were produced at a range of polymerization conditions including PAM concentration, amount of nitric acid, amount of ceric ion and polymerization temperature. Grafting was successful and homopolymerization of DADMAC was found not to occur. The graft polymers were characterized using NMR, charge titration, viscosity measurements, and gel fraction measurements.</p> <p> The copolymers were tested for flocculating properties using a model TiO2 system. The graft copolymers produced performed better than the backbone polyacrylamide, low and high molecular weigh polyDADMAC, and a commercial random copolymer of acrylamide and DADMAC. It was found that both the amount of charge and gel is very important in flocculation performance. However, the testing of the copolymers as a conditioner for a municipal sludge did not show improvement in the drainage rate.</p> / Thesis / Master of Engineering (MEngr)

Key Words: Thrombosis, Vascular Graft, Microfluidics, Wall Shear Stress / Vascular grafts are essential for the management of cardiovascular disease. However, the lifesaving potential of these devices is undermined by thrombosis arising from material and flow interactions on the blood contacting surface. To combat this issue, the use of antithrombogenic coatings has emerged as a promising strategy for modulating blood and graft interaction in vivo. Although an important determinant of graft performance, hemodynamics are frequently overlooked in the in vitro testing of coatings and their translatability remains poorly understood. We address this limitation with a microscale platform that incorporates vascular prosthesis and coatings with tuneable flow and surface conditions in vitro. As a proof of concept, we use the platform to test the thrombogenic performance of a novel class of lubricant infused (LIS) and antibody lubricant infused (anti-CD34 LIS) coated ePTFE vascular grafts in the presence of arterial wall shear stress, with and without the presence of endothelial cells. Our findings suggest lubricant infused coated ePTFE vascular grafts are thromboresistant under flow and may have potential for in vivo arterial grafting applications. It is moreover apparent that the microscale properties of the device could be advantageous for the testing and translation of novel antithrombogenic coatings or blood contacting prosthesis in general. / Thesis / Master of Applied Science (MASc)