Orientador: Mário Alexandre Coelho Sinhoreti / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-09-11T21:15:34Z (GMT). No. of bitstreams: 1 Brandt_WilliamCunha_D.pdf: 1998947 bytes, checksum: 914e15da8572efd8f5e7f4b69beb9370 (MD5) Previous issue date: 2010 / Resumo: O objetivo neste estudo foi analisar diferentes fontes de luz e fotoiniciadores e sua influência nas propriedades físicas e térmicas e na resistência da união (RU) de compósitos odontológicos experimentais contendo diferentes fotoiniciadores. Um compósito experimental contendo uma mistura de BisGMA, UDMA, BisEMA, TEGDMA e 65% em peso de partículas de carga silanizadas foi preparado com o uso dos fotoiniciadores CQ (Canforoquinona) e PPD (1-Fenil-1,2-Propanodiona). O co-iniciador usado foi a amina terciária dimetil amino etil metacrilato (DMAEMA). As fontes de luz utilizadas foram uma lâmpada halógena (XL 2500-3M/ESPE) e duas de diodo emissor de luz - LED (UltraBlue ISDMC e UltraLume LED 5-UltraDent). A mensuração da irradiância e do espectro de luz emitido pelos aparelhos foi realizada por meio de medidor de potência e espectrômetro (USB 2000), respectivamente. A curva de absorção dos fotoiniciadores foi aferida por um espectrofotômetro (Varian Cary 5G). As propriedades físicas e térmicas do material foram analisadas em Espectroscopia de Infravermelho Transformada de Fourier (FTIR), análise Termogravimétrica (TGA), análise Termo-Dinâmica-Mecânica (DMA), resistência à compressão (RC), resistência à compressão diametral (RCD) e módulo diametral (MD). Para o teste de RU, push-out foi realizado em cavidades cônicas preparadas em noventa incisivos bovinos. Porém, antes da realização do teste push-out, a dureza Knoop (DK) foi mensurada no topo e na base das restaurações. O monitoramento (tempo real) da reação de polimerização foi realizado utilizando FTIR (Prestige21) e o grau de conversão (GC) para cada segundo foi calculado e curvas GC x tempo obtidas. A taxa de conversão (TC) foi avaliada por meio de ajuste das curvas, utilizando regressão não-linear (Hill - 3 parâmetros). Todos os resultados (GC, TGA, DMA, RC, RCD, MD, DK e RU) foram submetidos à análise de variância dois fatores e as médias comparadas pelo teste de Tukey (5%). De acordo com os resultados de FTIR, que avaliou o DC (%), quando os compósitos foram fotoativados pelos LEDs, não existiu diferença nos valores de GC. Porém, quando o XL 2500 foi usado, o compósito com PPD mostrou valores de GC menores que os com CQ. Não existiram diferenças nas propriedades mecânicas (RC, RCD e MD) entre os compósitos quando fotoativados por qualquer fonte de luz. A análise termogravimétrica (TGA), usada para confirmar a quantidade de partículas de carga e a porcentagem de monômero residual, não mostrou nenhuma diferença estatisticamente significante desses dois fatores, independentemente do fotoiniciador ou fonte de luz utilizada. A análise Termo-Dinâmica-Mecânica (DMA) analisou a temperatura de transição vítrea (Tg) e a rigidez do material a 37°C. De acordo com os resultados, o fotoiniciador PPD e a fonte de luz UltraLume LED 5 produziram polímeros com maior densidade de ligações cruzadas, pois apresentaram os maiores valores de Tg. Nenhuma diferença foi encontrada na rigidez a 37°C. A avaliação da cinética e taxa de polimerização mostrou que o PPD produz reação de polimerização mais lenta, levando a maiores valores de RU. Os valores de DK mostraram que XL 2500 produziu os maiores valores tanto no topo como na base das restaurações, exceto para a fotoativação do PPD, que mostrou resultados de DK inferiores no topo das restaurações. Em geral, UltraBlue IS e UltraLume 5 não apresentaram diferenças entre si. Dessa forma, pode-se concluir que o PPD mostrou potencial para a iniciação da reação de polimerização, pois apresentou propriedades semelhantes às da CQ, aumentando a RU entre dente/restauração. Os LEDs, principalmente o UltraLume 5, produziram valores de GC semelhantes para todos os compósitos, enquanto o QTH produziu maior conversão para a CQ, comparado ao PPD. / Abstract: The aim of this study was to analyze the spectrum of different lightcuring units (LCUs) and photo-initiators and yours influence in the physical and thermal properties and bond strength (BS) of experimental resin composites with different photo-initiators. A blend with BisGMA, UDMA, BisEMA, TEGDMA and 65 wt% of silanated filler particles was prepared with CQ (Camphorquinone) and PPD (1-phenyl-1,2-propanedione) photo-initiator. Dimethylaminoethyl methacrylate (DMAEMA) was used as co-initiator. One quartz-tungsten-halogen - QTH (XL 2500, 3M/ESPE) and two light-emitting diode (LED) LCUs (UltraBlue IS, DMC and UltraLume LED 5, Ultradent) were used for photo-activation procedures. Irradiance (mW/cm²) was calculated by the ratio of the output power by the area of the tip, and spectral distribution with a spectrometer (USB 2000). The absorption curve of each photo-initiator was determined using a spectrophotometer (Varian Cary 5G). The physical and thermal properties were analyzed through of Fourier transformed infra-red spectroscopy (FTIR), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), compression strength (CS), diametral tensile strength (DTS) and diametral modulus (DM). For BS, push-out test was accomplished in prepared conical cavities in ninety incisive bovine. However, before the accomplishment push-out test, Knoop hardness (KH) was made in the top and botton of the restorations. The real-time polymerization of the experimental resins was evaluated by Fourier transform infrared spectroscopy (Prestige21) and the degree of conversion (DC) for each second was calculated and a curve DC x time obtained. The rate of polymerization (RP) was calculated considering data fitting and Hill's 3 parameter non-linear regressions were used. The all results obtained (DC, TGA, DMA, CS, DTS, DM, KH and BS) were evaluated using a two-way analysis of variance (ANOVA) and Tukey's test (5%). The FTIR results, which analyzed the DC (%), when the resin composites were photo-activated with the LEDs LCUs, there aren't differences in the DC values. However, when XL 2500 was used for photo-activation, the PPD-containing resins showed lower DC values that CQ-containing resins. There are not differences in the mechanical properties (CS, DTS and DM) among the composite resins, regardless LCU used. The TGA, used to confirm the weight percent filler and the lost residual monomer (%) in each composite resin, didn't show any difference, regardless photo-initiator or LCU used. The DMA analyzed the glass transition temperature - Tg (°C) and the storage modulus (E' - MPa) in 37°C. In agreement with the results, the photo-initiator PPD and the UltraLume LED 5 LCU produced polymers with higher cross-link density, because they presented the highest Tg values. No difference was found in the E' in 37°C. The evaluation of the kinetics and rate of polymerization showed that PPD produces a slower reaction of polymerization, taking to highest BS values. The KH values showed that XL 2500 produced the highest values in the top and botton of the restorations, except for PPD, that showed lower KH values in the top of the restorations. In general, UltraBlue IS and UltraLume 5 didn't present differences amongst themselves. In that way, it can be concluded that PPD showed potential for the initiation of the polymerization reaction, because it presented similar properties to CQ; however it increased the BS between tooth/restoration. The LEDs, mainly the UltraLume 5, produced similar DC values for all composite resins, while QTH produced higher conversion for CQ, compared to PPD. / Doutorado / Materiais Dentarios / Doutor em Materiais Dentários

Pyrrolizidine alkaloids are cytotoxic, carcinogenic, and anti-carcinogenic in vivo and in vitro, and they produce many hazardous effects in humans and animals. Pyrrolizidine alkaloids (PAs) also cross-link with DNA and/or protein. However, whether such cross-linking is important to the toxic action of PAs is not known. In addition, the exact mechanism underlying these DNA cross-links or cytotoxicity is also not clear. In three separate studies, I characterized the nature of PA-induced DNA cross-links and the relationships between PA structures and cross-linking potency. In the first study (Chapter II), I found that cross-linking potency of PA congeners coincided with their abilities to cause cytopathologic effects. Macrocyclic a,p-unsaturated diesters PAs and their pyrrolic metabolites were the most potent inhibitors of colony formation, and inducers of cytopathologic changes and megalocyte formation. The macrocyclic α, β-saturated diester PA and open diesters PAs slightly inhibited colony formation, and slightly changed cell morphology. Retronecine and indicine N-oxide were completely inactive. In the next study (Chapter Ill), I found that pyrrolic macrocyclic metabolites were more potent DNA cross-linkers than their parent compounds as determined by alkaline elution. The pyrroles of the macrocyclic diester PAs were potent DNADNA (inter- and/or intra) cross-linkers in BstEll-digested λ-phage DNA or pBR322 plasmid DNA but dehydroretronecine and indicine N-oxide were not. I also examined which DNA sequences were more susceptible to PA-induced cross-links by using a series of restriction endonucleases to determine sequence specificity. The most favorable cross-linking site for PAs appeared to be 5'd(GG) and 5'-d(GA) although other sites, 5'-d(CC) or 5'-d(CG), might be also preferable cross-linking targets. In the next study (Chapter IV), I characterized the nature of DNA-protein interactions induced by PAs, because I found in previous studies that PA-induced cross-links are largely protein associated. In PA or pyrrolic PA exposed cells, cross-linked proteins with molecular weights 40 - 60 kD were detected. Two-dimensional electrophoretic analysis revealed that these proteins were probably acidic in nature. In an in vitro system utilizing pBR322 or Bst Ell-digested λ-phage DNA. dehydrosenecionine induced DNAprotein cross-links with BSA, indicating that such interactions might be related to amino acid composition of protein. These results confirmed that PA-induced DNA cross-links (DNA-DNA, DNA-protein cross-links) are influenced by three structural features: the C1 ,2 unsaturation of pyrrolizidine ring, α, β-unsaturation, and size of the macrocyclic diester ring. The ability to form cross-links was closely related to the known toxic potencies of these PAs. From this research, I also conclude that DNA crosslinking is the most critical event leading to PA-related diseases and that crosslinking is due to pyrrolic metabolites of PAs, not via a common metabolite as was once thought.

A proteomic procedure for analyzing mouse left ventricular collagen by mass spectrometry has been developed. The procedure involves a purification step that removes non-collagenous cellular components from the collagen extracellular matrix, a step that solubilizes the collagen in aqueous solvents before it is proteolytically digested for analysis with ESI-LCMS/MS. Collagen from healthy and lathrytic mice has been positively identified by applying the SEQUEST database search algorithm to spectra from the collagen prepared using this procedure. Analysis shows that the relative percentage of collagen peptides detected in lathrytic tissue is significantly greater than that of the healthy tissue. These preliminary results suggest that the percentage of cross-linked collagen is lower in the lathrytic tissue as indicated by the greater protein sequence coverage obtained for this tissue. This procedure lays the ground work for future experimentation that has the ability to allow for the identification and quantification of cross-linked peptides.

Malgré un large éventail d'applications de la gélatine et en dépit de son utilisation très ancienne, sa composition et sa structure ne sont pas encore entièrement connues et comprises. La gélatine est obtenue à partir de tissus animaux (peaux ou os) et est le résultat de l'hydrolyse partielle du collagène. La production de gélatine la plus abondante est celle de peau de porc qui représentait 46% de la production totale en 2007. Parmi les nombreuses applications, la gélatine de peau de porc est utilisée comme ingrédient principal des gélules dures pour l'industrie pharmaceutique. Une propriété importante de ces gélules est qu'elles fondent dans l'eau à une température au-dessus de 30° C et libèrent facilement les médicaments qu’elles contiennent dans le tube digestif. Les gélules dures doivent répondre à des spécifications de dissolution strictes tout au long de leur durée de conservation d'environ cinq ans. Ainsi, un test de dissolution dans l'eau est appliqué à la gélatine artificiellement vieillie dans des conditions de température et d'humidité élevées. Bien qu'avant le vieillissement le taux de dissolution de la gélatine corresponde toujours aux besoins de l'industrie pharmaceutique, une grande variabilité du taux de dissolution est observée après vieillissement. De plus, cette variabilité de dissolution dépend de l'origine de production de la gélatine. Dans ce contexte, un premier objectif était de comprendre les mécanismes sous-jacents impliqués dans la variabilité de la qualité de dissolution de la gélatine de peau de porc. Un deuxième objectif était d'identifier d'éventuels "marqueurs" de la dissolution de la gélatine afin de prédire son comportement au cours du vieillissement. Trois différents sites de production ont été choisis: deux en Europe et un aux USA. Au cours du vieillissement, la formation de cross-links a été mise en évidence et parmi ces cross-links, la dityrosine a été identifiée comme marqueur du vieillissement. En outre, les taux d'amines et d'aldéhydes ont diminué. Etant donné que ces deux fonctions sont connues pour réagir ensemble; ce résultat suggère qu'elles pourraient former d'autres cross-links au cours du vieillissement. Le processus d'oxydation dans la gélatine a été clairement démontré. De plus, la quantité de triple-hélices et leur stabilité au chauffage ont diminué alors que la quantité de conformation aléatoire et, probablement, de boucles-β augmente. Les résultats ont mis en évidence que l'origine de production affecte la composition chimique de la gélatine. Par exemple, la quantité de cross-links formés, comme la dityrosine, dans les gélatines fraîches et vieillies, différait selon l'origine de production. Nous avons également pu souligner que l'environnement physico-chimique de l'arginine permettait de distinguer l'origine de production de la gélatine. En ce qui concerne la dissolution de la gélatine, celles présentant des taux de dissolution non conformes avaient plus de phase amorphe après vieillissement que les gélatines conformes. L'implication des lipides dans la diminution de la dissolution de la gélatine a également été mise en évidence. La haute teneur en fer était également liée à la diminution de la dissolution mais seulement dans un site de production, ce qui suggère que la variabilité de dissolution a probablement des causes multifactorielles et dépendantes de l'origine de production.Avec le dichroïsme circulaire, nous avons pu discriminer les gélatines conformes des non-conformes avant même le vieillissement de ces gélatines. Cependant, l'interprétation des résultats reste très difficile en raison du manque d'information dans la littérature. Un tel résultat est important pour prédire le comportement de la gélatine avant le vieillissement. De manière générale, nos résultats ont mis en évidence qu’il serait pertinent de contrôler et de réduire le niveau d'oxydation et la teneur en lipides de la gélatine pour diminuer sa variabilité de dissolution. (...) / Despite a wide range of applications of gelatin and despite its very former use, gelatin composition and structure remains not fully known and understood. It is derived from animal tissue (skins or bones) and is the result of partial hydrolysis of collagen. The most abundant gelatin production, which is the focus of the present work, is pig skin gelatin which represented 46% of total production in 2007. Among numerous applications, gelatin is used as the main ingredient of the hard capsules for the pharmaceutical industry. An important property of hard capsules is that they melt in water at a temperature above 30°C and easily release drugs in the human digestive tract. Hard capsules have to meet strict dissolution specifications all along a shelf life of about five years. Thus, a dissolution test in water is applied to the gelatin constituting the hard capsules, after being artificially aged under high temperature and humidity conditions. While before aging the dissolution rate of gelatin always fit with requirement of pharmaceutical industry, a high variability in dissolution rate is observed after aging. Moreover, this dissolution variability was shown depending on the gelatin origin of production. In this context, a first objective of this work was to understand the underlying mechanisms involved in the variability of the dissolution quality of pig skin gelatin. A second objective was to identify possible “markers” of gelatin dissolution in order to predict the behaviour of gelatin through aging. Three different sites of production were chosen: two in Europe and one in USA. Cross-links formation was evidenced during aging, and among them, dityrosine was expressly identified as a marker of aging. In addition the levels of amines and aldehydes were decreased. Given that these two functions could react together; this result suggests that they could form other cross-links. Oxidation process in gelatin was clearly demonstrated. Furthermore, the quantity of triple-helices and their stability to heating decreased while the quantity of random coil and, probably, β-turns conformations increased. The results highlighted that origin of production impacts the chemical composition of gelatin. For instance, the extent of cross-link formation, such as dityrosine, in both fresh and aged gelatins, differed according to the origin of production. It was also pointed out that the physico-chemical environment of arginine allowed the distinction of production origin of gelatin. Regarding the gelatin dissolution, those showing non-compliant dissolution rates exhibited higher content of amorphous phase after aging than compliant ones. The implication of lipids in the decrease of gelatin dissolution rate was also evidenced. The decrease in dissolution was linked to the iron content only in one production site supporting the fact that dissolution variability has probably multifactorial causes, depending on the origin of production. The compliant and non-compliant dissolution rates were discriminate even before aging of gelatins by circular dichroism. However, the results interpretation remains quite difficult due to lack of literature information.Such a result is of importance in a view of predicting the behavior of gelatin before aging. To display a general overview, our results highlighted that, in order to reduce variability in the dissolution of gelatin, controlling and reducing the oxidation level and the lipid content will be relevant levers. To study the structural conformation thoroughgoing small angles neutrons would be an interesting tool. To complete the characterization of gelatin composition, quantifying and profiling lipids and sugars would be useful to better understand the gelatin oxidative instability.

Streptococcus pyogenes is an important human pathogen. One of the most prominent virulence factors produced by S. pyogenes is SfbI, a surface adhesin composed of three domains: thioester domain (TED), proline-rich repeat domain (PRR) and fibronectin-binding repeat domain (FnBD). The structures and functions of TED and PRR and their contributions to the pathogenesis of streptococcal diseases are unknown. The interaction between PRR and its putative target, the intracellular actin cytoskeleton regulator Arp2/3, was investigated by both in vitro and in vivo studies. PRR was shown to inhibit Arp2/3-dependent actin polymerisation. The expression of PRR in HeLa cells caused disruption to the cytoskeleton of the cells. All data point towards a role of PRR in inhibiting the Arp2/3 complex but more evidence is needed to support this. The N-terminal domain of SfbI (TED) and four homologous domains from S. pyogenes, group G streptococci and Streptococcus pneumoniae were characterised by mass spectrometry, NMR spectroscopy and biochemical assays. All were shown to possess intramolecular thioester bonds, spontaneously formed between sides chains of Cys and Gln residues. Fibrinogen (Fg) was identified as the first binding target of bacterial TEDs with direct evidence that the thioester bond was involved in the interaction with Fg. A pull-down experiment using human plasma showed Fg is a specific binding partner of SfbI-TED. The binding sites were narrowed down to the thioester-forming Gln of SfbI-TED and Lys residues in the Fg-Aα chain, and binding potentially occurred via covalent isopeptide linkage. The data presented here suggest two new roles for SfbI, previously unknown in bacterial pathogenesis. The PRR may be the first bacterial inhibitor of the actin cytoskeleton acting by inhibiting the Arp2/3 complex. Thioester domains appear to be a shared common feature of surface proteins of many Gram-positive pathogens. They may form covalent crosslinks between bacteria and host tissue.

No description available.

No description available.

No description available.

Il est estimé qu'une fracture se produit toutes les trois secondes autour du monde, accompagné par un risque élevé d'invalidité ou même de mortalité. La connaissance des mécanismes de fractures dans une configuration de chargement représentatif d'une chute semble être d'un intérêt majeur pour le développement de méthodes dédiées à la prédiction du risque de fracture. La ténacité est un paramètre approprié lorsqu'on s'intéresse à ces mécanismes de fracture, elle détermine l'énergie nécessaire pour propager une fissure à travers l'architecture du tissu. L'objectif de cette étude est d'évaluer la ténacité de l'os cortical humain, considérant à la fois des conditions chargement quasi-statique et représentatif d'une chute sur sites anatomiques appariés. L'acquisition d'images en micro-tomographie ainsi qu'une mesure des cross-links ont été réalisées afin d'évaluer leur influence sur les mécanismes fracture du tissu. Les résultats ont montré que dans des conditions quasi-statiques, les différents sites anatomiques présentent des propriétés mécaniques différentes : le radius résiste mieux à une propagation de fissure. Dans des conditions de chute, il n'y a plus de différences entre ces sites, mais la ténacité décroit de façon significative par rapport au chargement standard. L'os cortical résiste mieux à une propagation de fissure dans des conditions quasi-statiques. Les analyses structurales et biochimiques ont montré des différences entre les sites anatomiques qui expliquent les différences mécaniques. Les caractéristiques architecturales du tissu sont déterminantes vis-à-vis des mécanismes de fracture dans des conditions quasi-statiques. Mais leur rôle lors d'une chute est moins évident. Ces résultats impliquent que la microstructure de l'os cortical n'est pas un déterminant majeur vis-à-vis du risque de fracture. De futures études doivent être réalisées afin de déterminer les paramètres décisifs dans des conditions représentatives d'une chute / A fracture is estimated every three seconds in the world, leading to an increased risk of impairment or even mortality. The biomechanical knowledge of bone fracture mechanisms in a fall configuration of loading is of great interests for the development of clinical method for the prediction of the risk of fracture. Toughness seems to be a good candidate to investigate this fracture process as it corresponds to the energy needed to propagate a crack through cortical bone complex microstructure. The aim of this study was thus to evaluate human cortical bone toughness parameter under both quasi-static and fall-like loading conditions paired anatomical locations. Micro-computed tomography images using synchrotron radiation and collagen cross-links maturation measurements were performed to investigate the influence of the tissue architecture on crack propagation. Results found showed that under quasi-static condition, the different anatomical locations present different mechanical behavior. Radius significantly better resist crack propagation than the other studied location. Considering a fall-like loading condition, no more difference is observed between the locations but a significant decreased is measured compare to the first configuration. Human cortical bone has a better capacity to resist crack propagation under a standard quasi-static loading condition. By investigating the tissue morphometric and biochemical parameters, we observed different organization from a location to another that explains the mechanical differences. The architectural features appear to be determinant for crack propagation mechanisms under quasi-static condition, but they play a lesser role under fall-like condition. These results imply that the tissue microstructure is not a determinant when dealing with the prediction of the risk of fracture. Further work has to be done to reach out which parameters are more determinants under a specific fall-like loading condition

In the present study, muscle growth and flesh quality have been investigated from both commercially farmed Atlantic halibut (Hippoglossus hippoglossus) (Aga marine AS, Norway)and halibut obtained from small-scale trials at Mørkvedbukta Research Station (Bodø University College, Norway). Morphometric techniques have been utilized to investigate fast muscle growth in halibut ranging from circa 2 g to 100 kg, and it was established that fast muscle fibre recruitment ceases when the fish attain approximately 81 and 177 cm, in the case of males and females, respectively. Different muscle fibre types were distinguished using histochemical (myosin ATPase and succinic dehydrogenase) and immunohistochemical (S-58, an antibody against slow muscle myosin) staining techniques. Females recruit twice as many fast muscle fibres compared to males, which allows them to reach a larger final size. Furthermore, the seasonal growth patterns during a one year production cycle in commercial farmed halibut revealed a winter depression in growth leading to loss of biomass, which was attributed to the maturation of males. Commercial farmed fish of equal size (~1.5 kg) showed sexual dimorphism of fast muscle fibre number, caused by a significantly higher rate of fast muscle fibre recruitment in females. During the winter season fast muscle fibres shrunk significantly, especially in male fish, as a consequence of loss of appetite, low water temperatures and sexual maturation. None of the female fish matured during the trial. Flesh quality of halibut deteriorated during winter and spring, since it had a softer appearance and significantly lower myotomal protein content, particularly in males. Cathepsin activity was measured using spectroscopy and showed a strong negative correlation to protein content, displaying a seasonal variation. The proteolytic depletion of fast muscle proteins affected the water holding capacity of the muscle (determined by centrifugation), which showed concomitant changes with the increase in cathepsin activity and drop in protein content. Despite the soft appearance, the firmness (shear force) of the flesh increased during the winter. The hydroxylysyl pyridinoline cross-link content of the collagen matrix, determined by HPLC, showed a strong correlation to the fillet texture. The increased firmness during the winter, a period of little (female) or negative growth (males), was probably due to an increased cross-linking of the collagen compartment. Partial sequences of IGF-I and IGF-II were cloned from fast muscle of Atlantic halibut, and their relative gene expression levels were determined along with those of cathepsin B, cathepsin D and IGF-IRa in male halibut using qPCR during a fasting and refeeding trial. Transcript levels of cathepsin B and to some extent cathepsin D were significantly higher during fasting than refeeding, suggesting an increased enzyme production during periods of food deprivation. A temporary increase in IGF-I transcripts was observed after 7 days refeeding suggesting that this growth factor is involved in muscle growth control. Both IGF- IRa and IGF-II were down-regulated during refeeding.