Krüppel-like factor 2 (KLF2) is expressed in endothelial cells in the developing heart, particularly in areas of high shear stress, such as the atrioventricular (AV) canal. KLF2 ablation leads to myocardial thinning, high output cardiac failure and death by mouse embryonic day 14.5 (E14.5) in a mixed genetic background. This work identifies an earlier and more fundamental role for KLF2 in mouse cardiac development in FVB/N mice. FVB/N KLF2-/- embryos die earlier, by E11.5. E9.5 FVB/N KLF2-/- hearts have multiple, disorganized cell layers lining the AV cushions, the primordia of the AV valves, rather than the normal single layer. By E10.5, traditional and endothelial-specific FVB/N KLF2-/- AV cushions are hypocellular, suggesting that the cells accumulating at the AV canal have a defect in endothelial to mesenchymal transformation (EMT). E10.5 FVB/N KLF2-/- hearts have reduced glycosaminoglycans in the cardiac jelly, correlating with the reduced EMT. However, the number of mesenchymal cells migrating from FVB/N KLF2-/- AV explants into a collagen matrix is reduced considerably compared to wild-type, suggesting that the EMT defect is not due solely to abnormal cardiac jelly. Echocardiography of E10.5 FVB/N KLF2-/- embryos indicates that they have abnormal heart function compared to wild-type. E10.5 C57BL/6 KLF2-/- hearts have largely normal AV cushions. However, E10.5 FVB/N and C57BL/6 KLF2-/- embryos have a delay in the formation of the atrial septum that is not observed in a defined mixed background. KLF2 ablation results in reduced Sox9, UDP-glucose dehydrogenase (UGDH), Gata4 and Tbx5 mRNA in FVB/N AV canals. KLF2 binds to the Gata4, Tbx5 and UGDH promoters in chromatin immunoprecipitation assays, indicating that KLF2 could directly regulate these genes. Thus KLF2 plays a role in EMT, through its regulation of important cardiovascular genes. E10.5 FVB/N KLF2-/- embryos show gaps in the endothelial lining at the dorsal aorta and a number of blood cells localized outside the aorta suggesting either hemorrhaging or inability of the hematopoietic progenitors to reach the aortic endothelium and enter circulation. This is not observed in KLF2-/- embryos in a mixed genetic background. In conclusion, KLF2-/- cardiovascular phenotypes are genetic background-dependent. KLF4 is another member of the Krüppel-like transcription factor family phylogenetically close to KLF2. It is known to play an important role in vascular regulation. Our studies show that in vascular development KLF4 plays a complementary role to KLF2, indicated by cranial hemorrhaging in E9.5 KLF2-/-KLF4-/- embryos in an undefined mixed background. This phenotype is absent in either of the single knockouts. The role of KLF2 and KLF4 in vascular development has not been studied as much as adult vascular regulation. This study begins to define the roles of these two transcription factors in development of blood vessels. Congenital heart and valve defects are a common cause of infant mortality. KLF2 has never been studied in this context. Thus this work is important for a better understanding of the biology of valve development.

Submitted by Fabíola Silva (fabiola.silva@famerp.br) on 2016-06-27T14:52:30Z No. of bitstreams: 1 marcelofelipekozak_dissert.pdf: 986000 bytes, checksum: 7f262464a429e4df84692f32c1e38c0d (MD5) / Made available in DSpace on 2016-06-27T14:52:30Z (GMT). No. of bitstreams: 1 marcelofelipekozak_dissert.pdf: 986000 bytes, checksum: 7f262464a429e4df84692f32c1e38c0d (MD5) Previous issue date: 2011-05-27 / Introduction: One of the most often and important complications after surgical treatment of atrioventricular septal defects is the left atrioventricular valve insufficiency. So, this study was conducted to identify risk factors for moderate or severe left atrioventricular valve regurgitation within 30 days of surgical repair of atrioventricular septal defects at our center. Methods: This was a retrospective study in which we evaluated the results of 104 consecutive patients that were operated on at our practice between 2002 and 2010. The following associated factors were considered: age, weight, Down syndrome, grade of preoperative atrioventricular valve regurgitation, abnormalities on the atrioventricular valve and the use of annuloplasty. Patients were separated in two groups according to type of AVSD: group I (complete) and group II (incomplete – partial and transitional). Characteristics of the 53 patients of the group I: the median patient age at the time of repair was 6.7 months; the median weight was 5.3 Kg; 86.8% had Down syndrome; at the time of preoperative evaluation, there were 26 cases with moderate or severe atrioventricular valve regurgitation (49.1%); annuloplasty was perfored in 34%; abnormalities on the valve were found in 11.3% of the cases. Characteristics of the 51 patients of the group II: The median patient age at the time of repair was 4.1 years; the median weight was 13.4 Kg; 37.2% had Down syndrome; at the time of preoperative evaluation, there were 23 cases with moderate or grater LAVVR (45.1%); abnormalities on the AV valve were found in 17.6% of the cases; annuloplasty was performed in 21.6% of the patients. Results: Group I - At the time of post-operative evaluation, there were 21 cases with moderate or severe left atrioventricular valve regurgitation (39.6%). After performing a multivariate analysis, the only significant factor associated with these grades of insufficiency within 30 days of surgical correction of complete atrioventricular septal defect was the absence of Down syndrome (p = 0.03). Group II - At the time of postoperative evaluation, there were 12 cases with moderate or greater LAVVR (23.5%). During univariate analysis, only absence of Down syndrome was statistically significant (p = 0.02). However, after a multivariate analysis, none of the factors reached significance. Conclusion: Absence of Down syndrome proved to be associated with moderate or severe post-operative left atrioventricular valve regurgitation in patients with complete AVSD. However, none of the factors studied was determinant of a moderate or greater LAVVR within the first 30 days of repair of incomplete AVSD at our center. / Introdução: Uma das complicações mais frequentes e importantes do tratamento cirúrgico do defeito de septo atrioventricular (DSAV) é a insuficiência residual da valva atrioventricular esquerda, tanto nas formas totais, como parciais e transicionais. Dessa forma, esse estudo foi conduzido para identificar fatores de risco associados à insuficiência da valva atrioventricular esquerda (IVAVE) de grau moderado ou importante nos primeiros 30 dias após correção de defeito de DSAV. Métodos: Dados de 104 pacientes com DSAV operados entre 2002 e 2010 foram avaliados retrospectivamente, sendo estudados os seguintes fatores de risco: idade e peso no momento da correção, ausência de síndrome de Down, grau de insuficiência da valva atrioventricular (AV) antes da correção, anormalidades na valva AV e uso de anuloplastia. Os pacientes foram separados em dois grupos de acordo com o tipo de DSAV: grupo I (total) e grupo II (parcial e transicional). Características dos 53 pacientes do grupo I: a mediana da idade foi de 6,7 meses e a do peso de 5,3 Kg; 86,8% tinham síndrome de Down; antes da operação, 26 pacientes apresentavam insuficiência pelo menos moderada da valva AV (49.1%); anuloplastia foi realizada em 34% dos pacientes; anormalidades na valva AV foram encontradas em 11.3% dos casos. Características dos 51 pacientes do grupo II: a mediana da idade foi de 4,1 anos e a do peso de 13,4 Kg; 37,2% tinham síndrome de Down; antes da operação, 23 pacientes apresentavam IVAVE pelo menos moderada (45,1%); anormalidades na valva AV foram encontradas em 17,6% dos casos; anuloplastia foi realizada em 21,6% dos pacientes. Resultados: Grupo I – Após a correção cirúrgica, 21 casos apresentaram IVAVE pelo menos moderada (39,6%). Pela análise multivariada, o único fator associado com IVAVE pelo menos moderada no pós-operatório foi ausência de síndrome de Down (p = 0,03). Grupo II - Após a correção cirúrgica, 12 casos apresentaram IVAVE pelo menos moderada (23,5%). Pela análise univariada, apenas a ausência de síndrome de Down teve significância estatística (p = 0.02). Porém, após análise multivariada, nenhum dos fatores teve significância estatística. Conclusão: Ausência de síndrome de Down foi determinante de IVAVE moderada ou importante nos primeiros 30 dias após correção de DSAV total. Todavia, nenhum dos fatores estudados foi determinante para tais graus de IVAVE entre os pacientes com DSAV parcial e transicional.

Submitted by Luciana Sebin (lusebin@ufscar.br) on 2016-09-28T18:30:58Z No. of bitstreams: 1 DissPVBM.pdf: 3462300 bytes, checksum: 9bcab5ab4f3125268a7797b49ace3fa7 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-10-10T18:38:38Z (GMT) No. of bitstreams: 1 DissPVBM.pdf: 3462300 bytes, checksum: 9bcab5ab4f3125268a7797b49ace3fa7 (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-10-10T18:38:48Z (GMT) No. of bitstreams: 1 DissPVBM.pdf: 3462300 bytes, checksum: 9bcab5ab4f3125268a7797b49ace3fa7 (MD5) / Made available in DSpace on 2016-10-10T18:39:04Z (GMT). No. of bitstreams: 1 DissPVBM.pdf: 3462300 bytes, checksum: 9bcab5ab4f3125268a7797b49ace3fa7 (MD5) Previous issue date: 2016-02-18 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Introduction: Pressure ulcers (PU) are common complications in patients with spinal cord injury (SCI). The peak pressure on the ischial region in individuals with SCI are higher than those found in subjects without physical disabilities and this fact is justified by sensitivity, motor and vasomotor changes. Objective: To compare the pressure distribution on the seat of the wheelchair of subjects with SCI using 3 different types of cushions (Roho®, Varilite® and Varilite®). Methodology: we selected 10 participants of both genders with SCI (n=05 tetraplegia and n=05 paraplegia). The analysis of the pressure on the seat was performed during two different situations: with the participant sitting in static posture and another step using the wheelchair for locomotion. Results: For the first step to Jay® showed the best rates for average pressure and also the contact area (p<0,001), the Roho® showed the best index for peak pressure (p<0,002). In the step with the wheelchair moving, Jay® showed the best average pressure (p<0,001), the Roho® had the lowest average for the peak pressure (p<0,002), and Varilite® provided the highest means for the contact area of the buttocks and thighs (p<0,006). All cushions evaluated showed lower values to those considered risk factors for PU, ratifying the importance of its use for the prevention. Conclusion: The use of cushions are effective measures to aid in the prevention of PU in people with SCI, but do not replace other ways of prevention. There is the need for proper cushion calibration and guidance on its use to get the desired effects. / Introdução: As úlceras de pressão (UP) são complicações comuns em pacientes com lesão medular (LM). O pico de pressão na região isquiática em indivíduos com LM são maiores do que aqueles encontrados em indivíduos sem deficiências e este fato é justificado por alterações motoras, sensitivas e vasomotoras. Objetivos: objetivou-se comparar a distribuição da pressão sobre o assento da cadeira de rodas de indivíduos com LM usando 3 modelos almofadas diferentes (Roho®, Varilite® e Varilite®); analisar a distribuição da pressão no assento utilizando três tipos de almofadas de posicionamento e alivio/distribuição de pressão para cadeira de rodas em sujeitos com lesão medular; determinar a diferença entre distribuição de pressão, pico de pressão, e área de contato entre as almofadas com o uso do X-sensor; identificar se a distribuição da pressão difere entre almofadas a partir de três experimentos: sentar com flexão de quadril e joelhos à 90º, sentar com as pernas cruzadas, sentar com elevação do apoio de pés e sentar durante um descolamento; comparar se há diferenças na distribuição da pressão em sujeitos com tetraplegia e paraplegia por lesão medular; e identificar a rotina de alivio de pressão no assento da cadeira de rodas, pelos sujeitos. Metodologia: foram selecionados 10 participantes de ambos os sexos com LM (n = 05 com tetraplegia e n= 05 com paraplegia). A análise da pressão sobre o assento foi realizada durante duas situações distintas: com o participante sentado em postura estática e mais uma etapa utilizando a cadeira de rodas para a locomoção. Resultados: Para a primeira etapa, a almofada Jay® mostrou as melhores taxas para a pressão média e também a área de contato (p <0,001), a almofada Roho e apresentou o melhor índice para pico de pressão (p <0,002). Na etapa com a locomoção da cadeira de rodas, a almofada Jay® mostrou a melhor pressão média (p <0,001), a Roho® teve a menor média do pico de pressão (p <0,002), e Varilite® as maiores médias para a área de contato a nádegas e coxas (p <0,006). Todas as almofadas avaliadas apresentaram valores inferiores aos considerados de risco para UP, ratificando a importância de seu uso para a prevenção. Conclusão: O uso de almofadas é uma medida eficaz para ajudar na prevenção de UP em pessoas com LM, mas não substituem outras formas de prevenção. Existe a necessidade da adequada calibração da almofada e orientação para a sua utilização a fim de se obter os efeitos desejados.

Neste trabalho foi feito um estudo de uma argamassa especial, à base de cimento e acrescida de vermiculita, látex e fibras curtas (PVA e vidro), visando a sua utilização em ligações entre elementos de concreto pré-moldado. Realizaram-se ensaios de corpos-de-prova cilíndricos de 50 mm x 100 mm para a determinação das características do compósito, tais como: resistência à compressão, resistência à tração e módulo de elasticidade. Foram moldados 20 traços do compósito, variando as quantidades de cada um dos materiais. Foram realizados ensaios de compressão em placas de espessuras 5, 10 e 20 mm para determinação da rigidez (relação entre a tensão e a deformação específica) e do afundamento pela aplicação de carga concentrada. Também foram realizados ensaios de ligações de blocos de concreto, com e sem almofada na emenda. Com base nos ensaios realizados, notou-se que ao se utilizar maiores quantidades de vermiculita, a tendência era de diminuir as resistências à compressão e à tração e também o módulo de elasticidade; entretanto, com a adição de látex e, sobretudo, de uma quantidade considerável de fibra à mistura, sua resistência praticamente se igualava à resistência do corpo sem vermiculita com a vantagem de evitar fissuras ou lascamento, tornando-se adequado para ser utilizado como elemento de apoio em ligações de concreto pré-moldado. Notou-se um acréscimo de resistência à compressão superior a 30% ao se utilizar almofada na emenda nos casos em que não há excentricidade nas ligações entre blocos de concreto. / This research deals with a special mortar made with cement, which it was added vermiculite, latex and short fibers (PVA and glass) to be used in connections between elements of precast concrete. It was made cylindrical samples of 50 mm x 100 mm for the determination of the characteristics of the composite, such as: compression strength, tensile strength and modulus of elasticity. It was made 20 mixtures of the composite, varying the amounts of each one of the materials. Compression tests were made in plates with thickness of 5, 10 e 20 mm for determination of the stiffness (relationship between stress and specific deformation) and deformation due the application of concentrated load. Connections tests on concrete blocks were also made, with cushion and without it in the connection. Based in these tests, it was noticed that when using larger amounts of vermiculite, the tendency was of reducing the compression strength and tensile strength and the modulus of elasticity too; however, with the addition of latex and, above all, of a considerable amount of fiber to the mixture, your strength practically was equaled to the strength of the material without vermiculite with the advantage of avoiding cracks or split, becoming adequate to be used as cushion in precast concrete connections. It was noticed an increment of larger compression strength than 30% when using cushion in the connection in the cases in that there is not eccentricity in the connections between concrete blocks.

Neste trabalho foi feito um estudo de uma argamassa especial, à base de cimento e acrescida de vermiculita, látex e fibras curtas (PVA e vidro), visando a sua utilização em ligações entre elementos de concreto pré-moldado. Realizaram-se ensaios de corpos-de-prova cilíndricos de 50 mm x 100 mm para a determinação das características do compósito, tais como: resistência à compressão, resistência à tração e módulo de elasticidade. Foram moldados 20 traços do compósito, variando as quantidades de cada um dos materiais. Foram realizados ensaios de compressão em placas de espessuras 5, 10 e 20 mm para determinação da rigidez (relação entre a tensão e a deformação específica) e do afundamento pela aplicação de carga concentrada. Também foram realizados ensaios de ligações de blocos de concreto, com e sem almofada na emenda. Com base nos ensaios realizados, notou-se que ao se utilizar maiores quantidades de vermiculita, a tendência era de diminuir as resistências à compressão e à tração e também o módulo de elasticidade; entretanto, com a adição de látex e, sobretudo, de uma quantidade considerável de fibra à mistura, sua resistência praticamente se igualava à resistência do corpo sem vermiculita com a vantagem de evitar fissuras ou lascamento, tornando-se adequado para ser utilizado como elemento de apoio em ligações de concreto pré-moldado. Notou-se um acréscimo de resistência à compressão superior a 30% ao se utilizar almofada na emenda nos casos em que não há excentricidade nas ligações entre blocos de concreto. / This research deals with a special mortar made with cement, which it was added vermiculite, latex and short fibers (PVA and glass) to be used in connections between elements of precast concrete. It was made cylindrical samples of 50 mm x 100 mm for the determination of the characteristics of the composite, such as: compression strength, tensile strength and modulus of elasticity. It was made 20 mixtures of the composite, varying the amounts of each one of the materials. Compression tests were made in plates with thickness of 5, 10 e 20 mm for determination of the stiffness (relationship between stress and specific deformation) and deformation due the application of concentrated load. Connections tests on concrete blocks were also made, with cushion and without it in the connection. Based in these tests, it was noticed that when using larger amounts of vermiculite, the tendency was of reducing the compression strength and tensile strength and the modulus of elasticity too; however, with the addition of latex and, above all, of a considerable amount of fiber to the mixture, your strength practically was equaled to the strength of the material without vermiculite with the advantage of avoiding cracks or split, becoming adequate to be used as cushion in precast concrete connections. It was noticed an increment of larger compression strength than 30% when using cushion in the connection in the cases in that there is not eccentricity in the connections between concrete blocks.

Ma thèse a pour objectifs d’étudier et d’améliorer le confort d’un coussin d’assise dans le cas d’un fauteuil roulant pour handicapé, afin de limiter au mieux, l’apparition des escarres.Mes travaux ont pour principal objectif de modéliser et de simuler numériquement un coussin de type nid d’abeille de marque ‘‘Stimulite® Honeycomb Cushion’’ en contact avec un fessier afin de pouvoir (i) modéliser le comportement mécanique de contact, (ii) d’évaluer la pression ainsi que la distribution des contraintes à l’interface coussin/fessier, et (iii) d’intégrer les échanges thermomécaniques.Par ailleurs, des essais expérimentaux ont été effectués pour quantifier les lois de comportement des matériaux constituants le coussin nid d’abeille. J’ai également utilisé une nappe permettant de mesurer la pression à l’interface coussin/fessier. Parallèlement, une caméra infrarouge a été utilisée pour mesurer la répartition de la température sur le coussin et le fessier pour une personne assise pendant une durée variable. / The aim of this thesis is to study and improve the comfort of a wheelchair cushion for handicapped, to reduce the appearance of pressure ulcers.In the study, the main objective is to model and simulate numerically a type of cushion, namely ‘‘Stimulite® Honeycomb Cushion Classis’’, in contact with a buttocks-tissue in order to (i) model the mechanical behavior of contact, (ii) evaluate the pressure and the stress distribution at the interface cushion/buttock-tissue, and (iii) integrate thermo-mechanical exchanges.Moreover, the experimental tests were carried out to quantify the law of behavior of material constituent of the honeycomb cushion. I also used a pressure-mapping sensor TexiMat® to measure the pressure at the interface cushion/buttocks-tissue.Meanwhile, an infrared camera was used to measure the temperature distribution on the cushion and buttocks-tissue of a person sitting during variable periods.

Die Analyse des Standes der Technik zu Simulationsmethoden im Werkzeugentwicklungsprozess zeigt die breiten Bestrebungen ganzheitliche Modelle zur Abbildung der Maschinen- und Werkzeugeigenschaften in der Prozesssimulation zu schaffen um die Werkzeuginbetriebnahme in Zukunft in die virtuelle Welt überführen zu können. Dabei werden die Einflüsse wie die Stößelkippung unter Last, die Durchbiegung der Werkzeugaufspannplatten, die Verformung des Ziehkissens und die elastische Nachgiebigkeit der Werkzeuge separat betrachtet. Es konnte kein Simulationsmodell identifiziert werden, welche alle relevanten Eigenschaften der Werkzeuge und der Maschinen zu einem Gesamtmodell vereint. Zudem fehlten Modellierungsansätze für wesentliche Teilaspekte einer ganzheitlichen Abbildung der Wechselwirkungen von Maschine, Werkzeug und Prozess. Insbesondere ist dabei die systematische Untersuchung zur Abbildung des Pinolentragbildes sowohl örtlich als auch über dem Pressenhub und der versteifende Einfluss der Werkzeugführung zu nennen. Mit der vorliegenden Arbeit konnte ein ganzheitliches FE-Prozessmodell mit den wesentlichen elastischen Eigenschaften der Maschine und der Werkzeuge erstellt werden. Wichtig ist dabei insbesondere die systematische Abbildung relevanter mechanischer Ziehkissenstrukturen als Ersatzmodell und die Integration der tatsächlichen Ziehkissenkraft im Prozessmodell. Bekannte Modellierungsansätze wie z.B. die Abbildung der Kippsteifigkeit des Stößelsystems und die Berücksichtigung der Durchbiegung der Werkzeugaufspannplatten wurden weiterentwickelt und in das Gesamtmodell implementiert. Für jedes Ersatzmodell wurde eine Strategie zur Modellerstellung und zur zweckmäßigen Parametrierung mit dem Ziel eines minimalen Zeit- und Kostenaufwandes vorgeschlagen. Die elastische Modellierung der Werkzeuge wurde mit einer systematischen Vorgehensweise hinterlegt und zeigt bei konsequenter Anwendung signifikant reduzierte Berechnungszeiten. Die Berücksichtigung der Ziehstäbe erfolgt in dieser Arbeit aufgrund der Einschränkungen des verwendeten FE-Solvers als Strukturmodell. Zusätzlich wurde ein Modellierungsansatz vorgestellt, welcher die analytische Berücksichtigung der Ziehstäbe auf elastischen Werkzeugstrukturen ermöglicht. Damit steht jetzt ein Prozessmodell mit den relevanten Maschinen- und Werkzeugeigenschaften zur Verfügung, welches durch eine einfache Parametrierung auf die jeweilige Prozess-Maschinen-Konfiguration angepasst werden kann. Dies ermöglicht eine deutlich genauere Abbildung des Pinolentragbildes, der daraus resultierenden Niederhalterdruckverteilung und damit des Materialeinzuges in die Matrize. Dieses erweiterte Prozessmodell ist damit in der Lage eine virtuelle Inbetriebnahme der Werkzeuge zu unterstützen und in Zukunft eine weitere Verkürzung des Inbetriebnahmeprozesses zu ermöglichen.

Orientador: Luis Carlos Paschoarelli / Resumo: Dos dispositivos de auxílio à mobilidade, a cadeira de rodas é o mais utilizado, proporcionando ao usuário, além do deslocamento, melhora na qualidade de vida, na saúde, no bem-estar social e econômico. É um equipamento comumente utilizado por tempo prolongado, estando sujeito à ocorrência de vibração e consequente transmissão da Vibração de Corpo Inteiro (VCI) ao usuário por meio das superfícies de contato, como os apoios para braços, pés, cabeça, encosto e assento. A VCI pode causar danos à saúde do usuário de cadeira de rodas se os seus níveis ultrapassarem os limites seguros. Desta forma, o objetivo principal deste trabalho foi verificar a influência das almofadas nos níveis de vibração transmitidos aos usuários de cadeira de rodas, tendo como principal foco de estudo a análise de diferentes tipos de almofadas e a vibração transmitida ao longo do eixo z, o mais afetado em posições sentadas. Também foram avaliadas as almofadas implementadas com uma superfície plana de madeira compensada. Trata-se de uma pesquisa quantitativa, aplicada, exploratória, experimental e transversal realizada com vinte e sete voluntários do gênero masculino, não usuários de cadeira de rodas. Os resultados mostram que a cadeira de rodas sem almofada transmite o menor nível de vibração [WAz=0,39m/s2]. As almofadas comerciais obtiveram valores de VCI entre WAz=0,45m/s2 e WAz=0,52m/s2. Os assentos implementados com uma superfície de madeira compensada apresentaram níveis de VCI de WAz=0,41m/s2 a WAz=... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Of the wheelchair mobility aids is the most used, providing the user, beides the displacement, improvement in the quaçity of life, health, social and economic well-being. It is a commonly used equipment for a long time, being subject to the occurrence of vibration and consequent transmission of Whole Body Vibration (WBV) to the user through contact surfaces, such as armrests, feet, headrest, backrest and seat. WBV can cause damage to the health of a wheelchair user if their levels exceed safe limits. In this way, the main objective of this work was to verify the influence of the cushions on the vibration levels transmitted to the wheelchair users, having as main focus the analysis of different types of cushions and the vibration transmitted along the z axis, the most affected in segred positions. Also evaluated were the pillows implemented with a flat plywood surface. It is a quantitative, applied, exploratory, experimental and cross-sectional study carried out with twenty-seve male volunteers, not wheelchair users. The results show that the wheelchair without cushion transmits the lowest level of vibration {WAz=0.39m/s2]. The commercial cushions obtained WBV values between WAz=0.45m/22 and WAz=0.52m/s2. The seats implemented with a plywood surface showed WBV levels of WAz=0.41m/s2 at WAz=0.44m/s2. It was concluded that the commercial cushions amplify the vibration when compared to the wheelchair without cushions, and the WBV levels measured in the research are relevant, ofte... (Complete abstract click electronic access below) / Doutor

Thesis (M.S.)--Air Force Institute of Technology, 2005. / "September 2005" Also available as a PDF file on the Air Force Institute of Technlogy website.

This work reports on the successful formation of supported multicomponent lipid bilayer membranes (sLBMs) from natural occurring lipids as well as synthetic lipids on a set of polymer cushions consisting of alternating maleic acid copolymers. Maleic acid copolymers provide a versatile platform to adjust the physico-chemical behaviour by the choice of the comonomer unit. The formation of sLBMs was triggered by a transient reduction of the electrostatic repulsion between the polymer cushions and the lipid vesicles by lowering the solutions pH to 4. Upon formation the stability of sLBMs was not affected by subsequent variations of the environmental pH to 7.2. Even drastic changes in the environmental pH (between pH 2 and pH 9) did not lead to delamination and proved the stability of the polymer sLBM. The degree of hydrophilicity and swelling of the anionic polymer cushions was found to determine both the kinetics of the membrane formation and the mobility of the lipid bilayer with lipid diffusion coefficients in the range from 0.26 to 2.6 µm2 s-1. An increase in cushion hydrophilicity correlated with a strong increase in the diffusion coefficient of the lipids. This trend was found to correlate with the kinetics of bilayer formation in the process of vesicle spreading. The observations strongly support the important role of the support’s polarity for the fluidity of the sLBM, which is probably related to the presence of a water layer between support and bilayer. The investigated polymer cushions are considered to open new options for the in situ modulation of lipid bilayer membranes characteristics to match the requirements for the successful integration of functional transmembrane proteins (TMPs). As each cushion exhibits different physico-chemical properties, the resulting behaviour of the sLBMs and TMPs could be exactly adjusted to the specific requirements of biological samples. This is exemplarily shown by the integration of the TMP beta amyloid precursor protein cleaving enzyme (BACE). Integrated BACE was observed to be mobile on all polymer cushions. On the contrary, no lateral mobility of BACE was found in solid sLBM. Furthermore, the activity of integrated BACE was analysed by the cleavage of an amyloid precursor protein analogue. Remarkably, the polymer cushions did not only enhance the mobility but were also found to increase the activity of BACE by a factor of 1.5 to 2.5 in comparison to solid sLBM. From the obtained results it is obvious that even small cytoplasmic domains of transmembrane proteins might not be preserved upon the integration in silica sLBM. The observed beneficial effects of the utilised polymer cushions on the mobility and activity of transmembrane proteins motivate further studies to clarify the general applicability of the polymer platform. Altogether, this polymer platform provides valuable options to form sLBM with varying characteristics to reconstitute transmembrane proteins for a wide range of possible future applications in biology. / Die vorliegende Arbeit beschreibt die Bildung von polymer unterstützten Lipiddoppelschichten zur Integration von transmembranen Proteinen. Das Polymerkissensystem besteht aus alternierenden Maleinsäurecopolymeren. Lipiddoppelschichten wurden durch die Steuerung der elektrostatischen Repulsion erzeugt: die Verringerung des pH-Wertes auf 4 wurde eine Erhöhung der adsorbierten Vesikelmenge auf den Polymeroberflächen induziert. Nach der erfolgten Bildung der Lipiddoppelschichten kann der pH-Wert beliebig variiert werden, ohne dass die Stabilität der Lipiddoppelschichten beeinflusst wird. Auch drastische Veränderungen des pH-Milieus (pH 2 - pH 9) führten zu keinen Veränderungen in der Membranintegrität. Der Grad der Hydrophilie und der Quellung der anionischen Polymerschichten beeinflusst sowohl die Bildung der Modellmembranen als auch die Mobilität der integrierten Lipidmoleküle. Dabei reichen die erzielten Lipiddiffusionskoeffizienten von 0.26 bis 2.6 µm2 s-1. Dabei ist die Mobilität direkt von der Hydrophilie des Substrates abhängig. Die beobachteten Ergebnisse zeigen deutlich die entscheidende Rolle der Polarität der verwendeten Substratoberflächen auf die Lipidmobilität, die sehr wahrscheinlich mit der Präsenz einer variablen Wasserschicht zusammenhängt. Die untersuchten Polymerkissen eröffnen neue Möglichkeiten für die insitu Modulierung der Charakteristika von Lipidschichten, um funktionale transmembrane Proteine zu integrieren. Aufgrund der unterschiedlichen physiko-chemischen Eigenschaften kann das Verhalten der Lipidschichten und der transmembranen Proteine nach den spezifischen Anforderungen des Modellsystems angepasst werden. Die funktionale Integration wurde am Beispiel des transmembranen Proteins BACE nachempfunden. Die Mobilität des integrierten BACE wurde auf allen Polymerkissen beobachtet. Im Gegensatz dazu wurde auf harten Substraten keine BACE Mobilität gefunden. Die Aktivität des integrierten BACE wurde durch die enzymatische Spaltung eines APP-Analogons nachgewiesen. Bemerkenswerteweise wurde ein Anstieg der BACE Aktivität auf den Polymerkissen um den Faktor 1,5 bis 2,5 im Vergleich zu den auf harten Substraten integrierten BACE beobachtet. Zusammenfassend, die verwendeten Polymerkissen bieten vielfältige Möglichkeiten Lipidschichten mit variierenden Eigenschaften für die Integration von transmembranen Proteinen zu erzeugen.