Orientadores: Américo Bortolazzo Correr, Mário Alexandre Coelho Sinhoreti / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-23T10:38:23Z (GMT). No. of bitstreams: 1 Feitosa_VictorPinheiro_D.pdf: 2456135 bytes, checksum: c15250b4b741e036f66121da12d96a07 (MD5) Previous issue date: 2013 / Resumo: O objetivo neste estudo foi avaliar o efeito da cadeia espaçadora (comprimento e polaridade) de cinco monômeros funcionais fosfatados, MEP (dois carbonos), MDP (dez carbonos), MDDP (doze carbonos), MTEP (cadeia mais hidrófila) e CAP-P (cadeia com hidrofilia intermediária) sobre a união química com dentina e cálcio, as propriedades físico-químicas e a adesão à dentina. Este estudo foi separado em 3 Capítulos. No Capítulo 1 foi verificada a influência da cadeia espaçadora de monômeros funcionais no grau de conversão, resistência coesiva, sorção de água e molhamento de adesivos experimentais de passo único. A fotoativação em todos os capítulos foi realizada com o aparelhos de luz de lâmpada halógena com irradiância mínima de 600mW/cm². Todos os dados foram submetidos à análise de variância de um fator e teste de Tukey (?=0.05). Os resultados mostraram que os diferentes monômeros promoveram grau de conversão semelhante quando adicionado em porcentagens molares iguais. Entretanto, a resistência coesiva foi diferente, com maiores valores para monômeros capazes de propiciar interações intermoleculares (MTEP, MDP e MDDP). A sorção de água e o molhamento sobre superfícies de dentina foram maiores utilizando os monômeros mais hidrófilos (polares). No Capítulo 2, o objetivo foi avaliar a interação química dos monômeros funcionais com cálcio e dentina. Foi analisada a formação de sais monômero-cálcio através da concentração de cálcio livre (Ca2+) em espectroscopia de absorção atômica (AAS), a interação de soluções aquosas dos monômeros com fatias de dentina antes e após a lavagem com água e etanol através de espectroscopia infravermelho transformada de Fourier (FTIR) e a presença dos monômeros sobre as fatias de dentina também foi observada em microscopia eletrônica de varredura. Os resultados mostraram que a união iônica com cálcio é maior com monômeros contendo cadeias espaçadoras longas e menos polares (MDP e MDDP). A estabilidade dessas ligações frente à lavagem foi afetada somente para o monômero com cadeias curta. A hidrofilia da cadeia não afetou a estabilidade da união química. No Capítulo 3, o objetivo foi avaliar a formação da ligação entre monômeros e cálcio e adesão de sistemas adesivos de passo único usando os monômeros estudados. Foi analisada a resistência de união à microtração após 24 horas e um ano de armazenagem em água, a absorbância de cálcio livre em AAS, a micropermeabilidade e a nanoinfiltração dos adesivos. Os resultados mostraram que a resistência de união inicial e a formação de ligações com cálcio foram menores para os monômeros com cadeias espaçadoras curtas e polares. A resistência de união foi reduzida após armazenagem somente para o monômero com cadeia espaçadora mais hidrófila (MTEP), provavelmente devido a maior micropermeabilidade e sorção de água. Houve pouca nanoinfiltração somente para monômeros com cadeias longas e hidrófobas. Como conclusão, observou-se que cadeias espaçadoras mais hidrófilas e mais curtas prejudicam a união química, a adesão e as propriedades físico-químicas dos monômeros ácidos funcionais / Abstract: The aim of this study was to evaluate the effects of spacer chain (length and polarity) of five phosphoric functional monomers, MEP (two carbons), MDP (ten carbons), MDDP (twelve carbons), MTEP (more hydrophilic spacer chain) and CAP-P (intermediate hydrophilicity spacer). It was assessed the chemical bonding with dentin and calcium, the physicochemical properties of one-step self-etch adhesives and the adhesion to dentin. This investigation was separated in 3 chapters. Chapter 1 verified the influence of spacer chain of functional monomers on the degree of conversion, ultimate tensile strength (UTS), water sorption and wettability of experimental all-in-one adhesives. Light-activation in all chapters was undertaken using halogen-lamp with minimal irradiance of 600mW/cm². All data were submitted to one-way ANOVA and Tukey's test (p<0.05). The outcomes showed that different monomers promote similar degree of conversion when added in same molar percentage. Nevertheless, their UTS were distinct, with high values for monomers able to promote intermolecular interactions. The water sorption and dentin wettability were greater with more hydrophilic (polar) monomers. In chapter 2, the purpose was to assess the chemical interaction of studied functional monomers with calcium and dentin. It was analyzed the formation of monomer-calcium salts through evaluation of free-calcium (Ca2+) in atomic absorption spectroscopy (AAS), the interaction of aqueous monomer-containing solutions with dentin slabs before and after rinsing with water and ethanol by means of Fourier-transform infrared spectroscopy (FTIR) and the presence of monomers onto the dentin slabs was imaged in scanning electron microscopy. The results displayed better ionic bond with calcium with monomers based on long and less polar spacer chains. The stability of such linkages was affected only for the monomer with short spacer chain. The hydrophilicity of spacer chain did not affect the stability of the chemical bond. In chapter 3, the aim was to evaluate the formation of bonds between monomers and calcium as well as the bonding performance of all-in-one adhesives using the investigated monomers. It was analyzed the microtensile bond strength after 24h and one year of water storage, the AAS absorbance of free-calcium, the micropermeability and the nanoleakage of adhesives. The outcomes showed that initial bond strength and formation of linkages with calcium were lower for monomers with short and polar spacer chains. The bond strength was reduced after aging only for the monomer with highly hydrophilic spacer chain, likely due to higher micropermeability. There was little nanoleakage only for monomers with long and hydrophobic spacer chains. As conclusion, it was observed that more hydrophilic and short spacer chains jeopardize the chemical bonding, the adhesion and the physicochemical properties of acidic functional monomers / Doutorado / Materiais Dentarios / Doutor em Materiais Dentários

The research involved determining the processes that occur during dye diffusion thermal transfer printing. Dye diffusion printing is a novel method of printing photo quality graphics from a personal computer. The process involves two polymer films coming into contact, one containing a dye, and the diffusion of the dye from this donor sheet onto the receiving sheet using heating elements to drive the diffusion process. In this high temperature, high pressure, and short time scale regime undesirable adhesion between the two polymer sheets is observed. It is this adhesion and its mechanisms that were investigated. Several types of homopolymers were used in.an attempt to obtain information on the processes involved in the adhesion of the two films during the printing stage. Initially dyes were absent from the polymer films to examine the polymer adhesion alone. It was hoped that the principal factors involved in the unusual joint forming conditions could be explained. The unusual conditions are high heat (250°C) and short time span (10-15 milliseconds). Polystyrene, poly (methyl methacrylate) and poly (vinyl acetate) were chosen to determine the effect of Glass Transition Temperature (T g), surface energies and molecular weight on the polymer adhesion. Initial results showed that the adhesion was a complex system. but it became clear that the t g of the polymers and the presence of small molecules and contaminants· were very important. Work with commercial polymers was undertaken to transfer the knowledge gained from the homopolymers to the more complicated commercial systems using poly (vinyl. chloride) and poly (vinyl butyral). To expand the understanding of the results small molecules and dyes were added to these commercial polymers to examine their effects. The surface of the samples were analysed using X-ray Photoelectron Spectroscopy (XPS) and Fourier Transform Infrared Spectroscopy (FTIR). This was used to determine if there was any migration of the small molecules to the surface of the polymer films. It was also useful in indicating the location of the dyes and how much penetration into the polymers is achieved by them. Atomic Force Microscopy (AFM) was implemented to analyse the surface morphology and gave an insight into the mechanism of the small molecule migration. The conclusions drawn were that the presence of small molecules had significant affect on the adhesion of the polymers. Compatible small molecules would act as plasticisers and lower the T g of the polymers giving rise to higher adhesion. Small molecules that were incompatible were found to migrate to the surface in large quantities and would act as weak boundary layers, significantly reducing the adhesion. Work in this area has shown that an autolayering mechanism is occurring that may be useful in producing a release mechanism for the commercial products.

Many animals are able to scale smooth surfaces using adhesive structures on their feet. These organs are either soft pads with a relatively smooth surface or dense arrays of microscopic adhesive hairs with both designs having independently evolved in diverse taxa of arthropods and vertebrates. Biological adhesive pads out-perform conventional adhesives in many respects, making them important models for biomimetics. Hairy pads have attracted particular attention, because it has become feasible to fabricate similar synthetic microstructures. Nevertheless, the detailed performance and functional properties have not been characterised for any natural fibrillar adhesive system, and many fundamental aspects are still not understood. The aim of this thesis was therefore to investigate the fibrillar adhesive system of leaf beetles as a model. To investigate the functional implications of hairy pad design, the attachment performance between hairy pads of the leaf beetle Gastrophysa viridula and smooth pads of stick insects (Carausius morosus) was compared. Adhesive and frictional stresses were found to be similar in smooth and hairy pads, inconsistent with contact splitting theory, which predicts higher adhesive stresses for fibrillar adhesives. Hairy pads showed a greater direction-dependence of friction forces than smooth pads, confirming the importance of the asymmetric design of individual setae for effortless detachment. Experiments with contaminating particles also showed that hairy pads removed contamination more rapidly and efficiently than smooth pads. Self-cleaning ability had not been previously documented for adhesive organs of insects. To investigate to what extent the hairy system is able to compensate for surface roughness, whole-body attachment forces were measured for varying roughness levels. Attachment was reduced for all length scales of surface roughness, but in particular for asperity sizes smaller than the diameter of individual seta tips. Leaf beetles possess adhesive pads on three tarsal segments, which vary in setal morphology. However, the functional implications of this variation are unknown. The mechanical and adhesive properties of individual pads were therefore tested and their use during climbing observed. Proximal pads were shown to be stiffer than distal pads, conferring stability during pushing. In contrast, the softer distal pads allowed better attachment to rough surfaces. Hence the morphological variation is explained by an effective division of labour between the pads. To investigate an extreme example of pushing in a hairy system, pad use was studied during jumping in flea beetles. The pushing forces needed during take-off were exclusively produced by the proximal pads, again confirming the division of labour. To characterise the effects of different hair morphologies and to understand how individual setae contribute to array and whole-animal performance, single hair forces were measured using a glass capillary cantilever. Male-specific discoidal hairs were shown to be both stiffer and more adhesive than pointed and spatula-tipped setae, likely affecting overall pad stability and attachment. This thesis has shown that hairy pads are similar to smooth pads in the magnitude of adhesive stress supported yet outperform them in detachability and self-cleaning. It was also demonstrated that there are considerable differences in design and performance even within setal arrays of the same insect, indicating the limitations of general models of fibrillar adhesion and underlining the importance of specialised adaptations.

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Cell adhesion molecules enhance Interactions between adjacent cells In order to mediate a large variety of functions of the Immune system. An antibody against the murine lymphocyte surface antigen MALA-2 has previously been shown to Inhibit mixed lymphocyte response. A λgt10 cDNA library from NS-1 cells was screened and a cDNA clone, K3-1.1, was previously isolated. It had significant homology to the human ICAM-1 gene. This thesis covers the isolation of a second cDNA clone, K4-1.1, and its comparison to K3-1.1 In terms of expression, function and distribution. The two clones are identical in sequence with the exception of the 5’ ends. Expression of these two clones was examined using a transient expression system of COS cell transfection. Cell surface expression of the K3-1.1 clone could not be detected by FACS analysis. Even when the 5' untranslated region of the K3-1.1 clone (which has 10 potential translation start sites) was removed, protein could not be detected at the cell surface, intracellularly, or extracellularly. However, K4-1.1 expression was detected at the cell surface. Northern blot analysis reveals that there are two distinct messages which are likely to be represented by the two clones. When the northern blot was probed with the 5' end of the K3-1.1 clone, only one of the messages was detected. This together with the result of Southern blot analysis suggests that the two messages are likely the result of alternate splicing. In order to examine the interactions of the murine ICAM-1 with the surface of other cells, an expression system which would produce large amounts of a secreted soluble form was established. The soluble protein was purified from the supernatant of transfected cells by an antibody-affinity column and used in preliminary binding assays. / Medicine, Faculty of / Medical Genetics, Department of / Graduate

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In epithelial cells, formation of stable adherens junction is essential for a number of important cell processes. The central protein responsible for creating cell-cell adhesion is known as E-cadherin. When the lamellipodia of migratory cells make contact, the cell is signaled to send E-cadherin/β-catenin complexes to the point of contact. Upon proper binding of two E-cadherin molecules further E-cadherins are signaled to cluster at the point of contact through cis lateral interactions and a passive diffusion trap mechanism. The actin cytoskeleton is also signaled through Rac1 to interact with the nascent adherens junction. As the adherens junction matures there are further actin cytoskeleton rearrangements and alterations to cell shape due to variable expression of the Rho GTPases. When adhesion in the adherens junction is stable the cell is able to become polarized by the assembly of tight junctions. Interference with any of the steps that lead to the development of a stable, mature, adherens junction results in various disease states such as cancer. Cancer can develop in epithelial cells due to E-cadherin dysfunction, particularly gastric, breast, ovarian, head and neck, and prostate cancer are seen. E-cadherin dysfunction can be caused by interference with proper transcription, N-glycosylation, and recycling. Transcription is most commonly disrupted due to acetylation of the E-cadherin promoter by improperly modulated transcriptional repressor, such as Snail. Aberrant Nglycosylation and/or modification with branching β1, 6 GlcNAc can interfere with the creation of stable adherens junction by interfering with E-cadherin binding. Increased endocytosis of E-cadherin via irregular Rho GTPase activity destabilizes adherens junctions. These interferences effect an epithelial to mesenchymal transition that can act as a metastatic cancer phenotype. E-cadherin serves a crucial function in cell-cell adhesion and preventing cells from exhibiting malignancy. It has been shown that restoration of its function in cancer cell lines reduces the invasiveness of cancer cells and returns to the cell to a normal epithelial phenotype. Knowledge of E-cadherin, its regulators, and association with the actin cytoskeleton will undoubtedly have clinical impacts in cancer treatment. However, understanding of E-cadherin is still incomplete, in particularly more studies need to be done in the area of Rho GTPases and N-glycosylation, There has also been recent controversy in identifying the principal molecule that links the actin cytoskeleton and α- catenin to mediate the binding of the E-cadherin/β-catenin complex to actin.

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No description available.