Bioengineered skin substitutes have been developed to treat burn and non-healing wounds; however limitations still hinder their clinical success rates. Optimizing these current design strategies requires an understanding of how biochemical and topographical features of the native tissue modulate keratinocyte processes involved in tissue functionality. In this thesis, a novel bioengineered skin substitute was developed that contains a microfabricated basal lamina analog that recapitulates the native microenvironment found at the dermal-epidermal junction (DEJ). In native skin, this microenvironment consists of both biochemical and topographical cues which play critical roles in maintaining tissue architecture and overall homeostasis with the external environment. Therefore, we hypothesize that microfabricated basal lamina analogs with extracellular matrix cues and three-dimensional features that mimics the cellular microenvironment of the DEJ will promote enhanced epithelialization and increase epidermal stem cell clustering on the surface of bioengineered skin substitutes. We determined that the extracellular matrix protein fibronectin (FN) found in the cellular microenvironment of the DEJ enhanced keratinocyte attachment, proliferation, and epithelialization of a collagen based basal lamina analog. It was also found that the collagen material used to create the basal lamina analog as well as the FN conjugation strategy to this material significantly influenced the bioactivity of FN and its ability to modulate keratinocyte functions through integrin based mechanism. To investigate spatial tissue organization and the role it plays in the cellular microenvironment of the DEJ on epithelialization and epidermal stem cell localization, we used photolithography coupled with materials processing techniques to create microfabricated basal lamina analogs. It was determined that epidermal thicknesses found in narrow channels of microfabricated basal lamina analogs (50 µm and 100 µm widths with 200 µm depths) were similar to cultures on de-epithelialized acellular dermis and native foreskin tissues after 7 days of in vitro culture. We also determined that the microfabricated basal lamina analogs created an epidermal stem cell niche that promoted epidermal stem cell clustering in the channels which is critical for longevity of the tissue. Overall, we developed a platform technology that was specifically used to produce a highly functional bioengineered skin substitute with regenerative capacity that mimics native skin. We anticipate through the use of this technology, we can further improve bioengineered skin substitutes by incorporating epidermal structures of native skin including hair follicles and sweat glands as well as improve overall cosmetic appearance. Additionally, this novel bioengineered skin substitute can serve as a model system to further our understanding of pathological conditions and diseases of the skin as well as facilitate robust preclinical screenings of epidermal responses to new therapeutic agents as well as to cosmetic and chemical products.

Orientador: Eduardo Hochuli Vieira / Coorientadora: Alessandra Marcondes Aranega / Banca: Roberta Okamoto / Banca: Idelmo Rangel Garcia Junior / Resumo: Objetivos: Comparar através de análise hitométrica e imunoistoquimica o comportamento do ChronOs® (β-TCP) e do Bio-Oss® (Osso bovino inorgânico ) puros e misturados ao osso autógeno na proporção 1:1 em seios maxilares de humanos. Metodologia: 30 pacientes foram convidados para participar deste trabalho, resultando em 30 seios enxertados com osso autógeno puro (grupo A (controle)), ChronOs® puro (grupo C), ChronOs® em adição de osso autógeno na proporção 1:1(grupo CA), Bio-Oss® puro (grupo B) e Bio-Oss® em adição de osso autógeno na proporção de 1:1 (grupo BA), onde foram realizadas biopsias 6 meses após a realização desses enxertos e analisadas através de histometria (analisadas através do software ImageJ) e imunoistoquimica (RUNX2, VEGF e Osteocalcina). Os resultados foram tabulados, o teste de Shapiro-Wilk foi aplicado para avaliação da normalidade, em seguida foram aplicado os testes Kruskal-Wallis e Anova 1 fator para os dados paramétricos e não paramétricos sucetivamente e o teste de Tukey como pós teste. Resultados: Para neoformação óssea o grupo A foi maior que os grupos B e BA e o grupo CA foi maior que o grupo BA (p<0,05). Para os remanescentes de biomateriais o grupo BA apresentou um número maior que os grupos Chronos C, CA e A (p<0,05). Para tecido mole o grupo C foi maior que o grupo B (p<0,05). O resultado das imunomarcações mostrou marcação fraca para RUNX 2 nos grupos A, C, B e BA e marcação moderada para o grupo CA. Marcação intensa para VEGF nos grupos B e CA ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Objectives: To compare the performance of ChronOs® (β - TCP) and Bio - Oss® (Inorganic bovine bone) pure and mixed with autogenous bone in a 1: 1 ratio in maxillary sinuses of humans through h i s tometric and immunohistochemical analysis. Metodology : 30 patients were invit ed to participate of this study, resulting in 3 0 grafted sinuses with pure autogenous bone (group A (control) ), pure ChronOs® (group C), ChronOs® in addition 1: 1 autogenous bone (group CA), pure Bio - Oss® (group B) and Bio - Oss® in addition 1: 1 (group BA), w h ich biopsies were performed 6 months after the grafting and analyzed by histology (analyzed using ImageJ software) and immunohistochemistry (RUNX2, VEGF and Osteocalcin). The results were tabulated, the Shapiro - Wilk test was applied to evaluate the normal ity, then the Kruskal - Wallis and Anova 1 tests were applied for the parametric and non - parametric data and Tukey test as post test was applied . Results: The group A was higher than B and BA groups, and the group CA was higher than the BA group (P <0.05). For the remainder of biomaterials, BA group presented a higher number than Chronos C, CA and A groups (P <0.05). For soft tissue, group C was greater than group B (P <0.05). The immunolabeling results showed poor labeling for RUNX 2 in groups A, C, B and B A and moderate labeling for CA group. Intense labeling 25 for VEGF in B and CA groups, moderate in groups A and C and weak in BA group . For Osteocalcin, there was an intense marking ... (Complete abstract electronic access below) / Mestre

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Typescript. / Digitized by Kansas Correctional Industries

Within the last decade, the importance of flexibility and efficiency has increased in the manufacturing sector. The rising level of uncertainty in consumer preferences has caused many organizations to aggressively search for cost reductions and other sources of competitive advantage. This fact has resulted in an increased implementation of advanced manufacturing technologies (AMT). A number of studies propose that the implementation of AMT must be accompanied by a shift in supporting organizational practices to realize the greatest performance enhancement. As yet, the complementarities between organizational policies and AMT have not been determined. Using assumptions about complementarities in manufacturing made by Milgrom and Roberts (1995) in conjunction with a comprehensive AMT survey (Survey of Advanced Technology in Canadian Manufacturing-1998) a model of manufacturing plant productivity was developed. Constrained regression analysis reveals that the use of AMT, as well as various organizational policies, depends both on the size of the plant as well as the industry in which it operates. Factor analysis of the over 70 variables found that regardless of the nature of the variable (business strategy, source of implementation support, AMT, etc. ), all design elements factored together. The factor analysis also shows that large firms who use AMT also have many design technologies. This result differs for smaller firms where the use of AMT is highly correlated with perceived benefits of the technology and a large number of sources of implementation support. The analysis also supports the distinction of high technology (highly innovative) industries and low technology (low levels of innovation) industries since electronics, chemicals and automotive have a large percentage of plants with all of the model factors whereas the textile, non-metal and lumber industries have very few plants with all of the model factors. The results show that there are important differences that should be considered when creating policies to encourage innovation and the use of AMT for the various manufacturing industries and plant sizes.

Within the last decade, the importance of flexibility and efficiency has increased in the manufacturing sector. The rising level of uncertainty in consumer preferences has caused many organizations to aggressively search for cost reductions and other sources of competitive advantage. This fact has resulted in an increased implementation of advanced manufacturing technologies (AMT). A number of studies propose that the implementation of AMT must be accompanied by a shift in supporting organizational practices to realize the greatest performance enhancement. As yet, the complementarities between organizational policies and AMT have not been determined. Using assumptions about complementarities in manufacturing made by Milgrom and Roberts (1995) in conjunction with a comprehensive AMT survey (Survey of Advanced Technology in Canadian Manufacturing-1998) a model of manufacturing plant productivity was developed. Constrained regression analysis reveals that the use of AMT, as well as various organizational policies, depends both on the size of the plant as well as the industry in which it operates. Factor analysis of the over 70 variables found that regardless of the nature of the variable (business strategy, source of implementation support, AMT, etc. ), all design elements factored together. The factor analysis also shows that large firms who use AMT also have many design technologies. This result differs for smaller firms where the use of AMT is highly correlated with perceived benefits of the technology and a large number of sources of implementation support. The analysis also supports the distinction of high technology (highly innovative) industries and low technology (low levels of innovation) industries since electronics, chemicals and automotive have a large percentage of plants with all of the model factors whereas the textile, non-metal and lumber industries have very few plants with all of the model factors. The results show that there are important differences that should be considered when creating policies to encourage innovation and the use of AMT for the various manufacturing industries and plant sizes.

No description available.

No description available.

Synthesis of chemically modified or ion-substituted hydroxyapatite (HA) as a bioactive bone replacement material is of great interest since the main component of hard tissues in vertebrates is a substituted apatite. The most abundant species in natural bone mineral other than calcium and phosphate ions is carbonate ions. Carbonate ions can be substituted at 2 distinct sites in the HA lattice; the hydroxide (OH) site and the phosphate (PO4) site. Synthetic silicate substituted HA (SiHA) and carbonate-substituted HA (CHA) have each previously been shown to enhance new bone formation when compared to HA in vivo. The positive bioactive properties that result, individually, from carbonate or silicate substitution led to the hypothesis that simultaneous co-substitution of these two ions in to the HA lattice would lead to further improved bioactivity. A range of novel silicate and carbonate co-substituted HA (SiCHA) materials were prepared with silicate substitution of up to 12.5 wt% (3.8 wt% Si) and carbonate substitution up to 8.2 wt%. These compositions were characterised extensively, examining both their chemical and physical attributes. These compositions were single phase after sintering in a wet CO2 atmosphere to near-theoretical density, and contained carbonate ions on both hydroxide and phosphate sites. The grain sizes of these ceramic specimens of these compositions were intermediate between those of CHA and SiHA controls. Further controlled synthesis demonstrated that carbonate and silicate ions could be substituted in non-equimolar quantities, and increased amounts of carbonate could be substituted independently on to the hydroxide site of the SiCHA samples. The biological response to these materials was assessed by completing direct and indirect cell culture experiments using both the MG-63 osteoblast-like cell line and primary human osteoblast (pHOB) cells. The silicate and carbonate co-substituted materials and their dissolution products were not toxic to either of the cell lines, and cell proliferation was observed with all materials studied. The effect of the synthesis route on the purity of silicate-substituted hydroxyapatite (SiHA) was also assessed, with a particular focus on the role of tetraethyl orthosilicate (TEOS) as the source of silicate. The outcomes of this study showed that the final composition of SiHA was strongly dependent on how and when the tetraethyl orthosilicate (TEOS) solution was incorporated during the precipitation reaction.

Diss. (sammanfattning) Umeå : Univ., 2003. / Härtill 5 uppsatser.