Made available in DSpace on 2016-06-02T19:02:41Z (GMT). No. of bitstreams: 1 3965.pdf: 3863042 bytes, checksum: f995d87531cc46a186a0c566c0be57ea (MD5) Previous issue date: 2011-12-02 / This study aimed to evaluate the effects of low intensity laser therapy (LLLT) (830nm, 120J/cm2, 100mW) and implantation of Biosilicate® scaffolds, associated or not, in histological aspects, biomechanical properties of the bone callus and immunoexpression of proteins, growth and transcription factors related to different stages of bone repair, at 15, 30 and 45 days after surgery of bone defects induced in the tibia.of rats. For this, three studies were performed in which a total of one hundred and twenty male Wistar rats (3 months ± 280 g) were submitted to bilateral tibial defects and randomly distributed in four experimental groups with 30 animals each. In the first study the effects of the implantation of Biosilicate® scaffolds in bone defects of rats were investigated in two groups: bone defect group (GC) and bone defect treated with Biosilicate® scaffold group (GB). The implantation of the scaffold was performed subsequent to surgery of bone defect. Histological analysis revealed that animals of GB showed newly formed bone better organized at 30 and 45 days after surgery. The immunohistochemical analysis demonstrated that the Biosilicate® scaffold promoted a higher expression of COX-2 on days 15 and 30 after surgery, immunostaining positive of RUNX-2 in all periods, increased expression of RANKL on day 15 and positive immunoexpression of BMP-9 on the 45th day. However, the Biosilicate® scaffold did not increase the mechanical properties of bone callus. Thus, the implantation of Biosilicate® scaffold was effective in stimulating the repair of tibial defects, however, was not able to improve their mechanical properties. In the second study, the spatialtemporal changes in the process of bone healing in defects treated with LLLT were evaluated in two groups: GC and bone defect treated with laser group (GL). The laser treatment started immediately following the surgery of bone defects and have been 8, 15 or 23 sessions with an interval of 48 hours between them. The histological and morphometric analysis revealed that the GL showed better tissue organization at 15 and 30 days after surgery, and biggest area of newly formed bone at day 15. The immunohistochemistry showed that the LLLT promoted higher expression of COX-2 at day 15, immunostaining of RUNX-2 positive in all periods, higher immunoexpression of BMP-9 on day 30 and higher immunoreactivity of RANKL at day 15. However, the LLLT did not increase the biomechanical properties of bone callus. Thus, the LLLT improved the process of bone healing, but was unable to improve its biomechanical properties. In the third study the effects of the association of LLLT with implants of Biosilicate® scaffolds in bone healing were investigated in three experimental groups: GC, GB and Biosilicate® scaffold irradiated with laser group (GBL). The implantation of the scaffold was performed following the surgery of bone defect. The laser treatment started immediately after surgery and were performed 8, 15 or 23 sessions with an interval of 48 hours between them. At 15 days after surgery, the histological analysis revealed granulation tissue and newly formed bone juxtaposed to the surface of scaffolds in GB and GBL. Thirty days after injury, the GB and GBL had better organized newly formed bone compared to the CG. At day 45 was possible to observe granulation tissue in the defects of the GBL. In the GB, the peak of immunoexpression of COX-2 occurred on the 15th day and in the GBL, on the 30th day. The GB and GBL showed positive immunoexpression of BMP-9 up to 45th day after surgery, while RANKL immunoexpression was higher in the GBL at day 30. However, 30 and 45 days after injury, the animals of GB and GBL showed statistically lower values of maximum load compared to the CG. Thus, the association of the scaffold Biosilicate® with laser irradiation has osteogenic activity during the bone repair, however, the scaffold Biosilicate® associated or not with the laser irradiation is not effective to improve mechanical properties of the bone callus. Finally, we concluded that LLLT (λ = 830 nm, 120J/cm2) and implantation of Biosilicate® scaffolds, associated or not, were effective to stimulate the bone consolidation by improving the development of newly formed bone and activating immunoexpression of proteins, growth and transcription factors related to different stages of bone healing in tibial defects in rats. However, these therapeutic modalities associated or not, were unable to improve mechanical properties of the bone callus. / Este trabalho teve como objetivo avaliar os efeitos da terapia laser de baixa intensidade (LLLT) (830nm, 120J/cm2, 100mW) e do implante de scaffolds de Biosilicato®, associados ou não, nos aspectos histológicos, propriedades biomecânicas do calo ósseo e na imunoexpressão de proteínas, fatores de crescimento e de transcrição relacionados a diferentes etapas do reparo ósseo, ao 15º, 30º e 45º dia após a cirurgia de defeitos ósseos induzidos em tíbias de ratos. Cento e vinte ratos machos da linhagem Wistar (3 meses de idade ± 280 gramas) foram submetidos a defeitos tibiais bilaterais e distribuídos aleatoriamente em 4 grupos experimentais com 30 animais cada. No primeiro estudo investigaram-se os efeitos do implante de scaffolds de Biosilicato® em defeitos ósseos de ratos, a partir de dois grupos experimentais: grupo defeito ósseo controle (GC) e grupo defeito ósseo tratado com scaffold de Biosilicato® (GB). O implante do scaffold foi realizado em seguida à cirurgia de defeito ósseo. A análise histológica revelou que os animais do GB apresentavam osso neoformado mais organizado ao 30º e 45º dia após a cirurgia. A imunoistoquímica demonstrou que o scaffold de Biosilicato® promoveu maior expressão de COX-2 nos dias 15 e 30 de após a cirurgia, imunoexpressão positiva de RUNX-2 em todos os períodos, maior expressão de RANKL no 15º dia e imunoexpressão positiva de BMP-9 no 45º dia. Porém, o scaffold de Biosilicato® não aumentou as propriedades mecânicas do calo ósseo. Assim, o implante de scaffold de Biosilicato® foi eficaz em estimular o reparo de defeitos tibiais, porém, não foi capaz de melhorar suas propriedades mecânicas. No segundo estudo, foram avaliadas as mudanças temporais-espaciais no processo de reparo ósseo em defeitos tratados com LLLT, a partir de dois grupos experimentais: GC e grupo defeito ósseo tratado com laser (GL). O tratamento com laser iniciou-se imediatamente após a cirurgia dos defeitos ósseos e realizaram-se 8, 15 ou 23 sessões, com um intervalo de 48h entre elas. As análises histológica e morfométrica revelaram que o GL apresentou melhor organização tecidual aos 15º e 30º dias após a cirurgia, e maior área de osso neoformado no 15º dia. A imunoistoquímica mostrou que a LLLT promoveu maior expressão de COX-2 no 15º dia, imunoexpressão positiva de RUNX-2 em todos os períodos avaliados, maior imunoexpressão de BMP-9 no 30º dia e maior imunorreatividade do RANKL no 15º dia. Porém, a LLLT não aumentou as propriedades biomecânicas do calo ósseo. Assim, a LLLT melhorou o processo de consolidação óssea, mas não foi capaz de melhorar suas propriedades biomecânicas. O terceiro estudo investigou os efeitos da associação da LLLT com implantes de scaffolds de Biosilicato® na consolidação óssea, a partir de três grupos experimentais: GC, GB e grupo scaffold de Biosilicato® irradiado com laser (GBL). O implante do scaffold foi realizado em seguida à cirurgia de defeito ósseo. O tratamento com laser iniciou-se imediatamente após a cirurgia e foram realizadas 8, 15 ou 23 sessões, com um intervalo de 48h entre elas. Ao 15º dia pós-lesão a análise histológica revelou tecido de granulação e osso neoformado justapostos à superfície dos scaffolds no GB e GBL. Trinta dias após a lesão, o GB e GBL apresentavam osso neoformado mais organizado em comparação ao GC. Ao 45º dia, foi possível observar tecido de granulação nos defeitos do GBL. No GB, o pico de imunoexpressão da COX-2 ocorreu no 15º dia e no GBL, no 30º dia. Os GB e GBL apresentaram imunoexpressão positiva da BMP-9 até o 45º dia após a cirurgia, enquanto que para o RANKL, a imunoexpressão foi maior no GBL no 30º dia. No entanto, 30 e 45 dias após a lesão, os animais dos GB e GBL apresentaram valores estatísticamente menores de carga máxima em comparação ao GC. Assim, a associação do scaffold de Biosilicato® com o laser exerce atividade osteogênica durante o reparo ósseo, no entanto, o scaffold de Biosilicato® associado ou não a irradiação laser não é eficaz em melhorar as propriedades mecânicas do calo ósseo. Finalmente, podemos concluir que a LLLT e o implante de scaffolds de Biosilicato®, associados ou não, foram eficazes em estimular a consolidação óssea, melhorando o desenvolvimento de osso neoformado e ativando a imunoexpressão de proteínas, fatores de crescimento e de transcrição relacionados a diferentes etapas do reparo ósseo em defeitos tibiais em ratos. No entanto, estas modalidades terapêuticas, associadas ou não, não foram capazes de melhorar as propriedades mecânicas do calo ósseo em ensaio de flexão na posição de tração.

Made available in DSpace on 2014-07-29T15:07:31Z (GMT). No. of bitstreams: 1 Daniel Barbosa.pdf: 1143657 bytes, checksum: d56a1f0787d16e510afed007895c5973 (MD5) Previous issue date: 2010-10-24 / Abdominal wall defects may occur in fairly all animal species, and frequently demand corrective surgical treatment including implants of meshes, such as polypropylene. However, this biomaterial is not free from complications, what stimulates constant researches for new biomaterials that present certain advantages. Due to its well known biocompatibility, poliHEMA hydrogel was the chosen biomaterial for experimental abdominal wall implant associated to polypropylene mesh. This essay compared tissue responses to the employment of polypropylene mesh alone (group PP) and polyHEMA Hydrogel film associated to polypropylene mesh (group PH) on the correction of induced abdominal wall defects on bitches. Twelve mongrel adult female dogs, weighting from 10 to 20 kg, were divided in two equal groups. The animals from group PP received the polypropylene mesh implant whilst those from group PH received polyHEMA hydrogel coated polypropylene mesh to replace the abdominal transverse muscle. Six animals from each group were submitted to surgical procedure to remove the meshes at 30 and 60 days of the postoperative period. Tissue repairing phenomena such as: chronic inflammatory reaction, giant cell presence (foreign body chronic granulomatous inflammatory reaction) and connective tissue proliferation were microscopically evaluated. It may be concluded that polyHEMA hydrogel as a coating agent on polypropylene mesh implanted onto abdominal wall of female dogs triggers greater deposition of type I collagen, than polypropylene mesh alone. / Os defeitos na parede abdominal estão presentes em praticamente todas as espécies animais e não raro demandam tratamento cirúrgico corretivo com implantação de telas como a de polipropileno. Contudo esse biomaterial não é livre de complicações, o que impulsiona a constante pesquisa na busca de novos biomateriais que apresentem vantagens. O hidrogel de poliHEMA por ser reconhecidamente biocompatível foi o biomaterial de escolha para a implantação experimental em associação à tela de polipropileno na parede abdominal. Este estudo comparou as respostas teciduais do uso da tela de polipropileno isolada (grupo PP) e o filme de hidrogel de poliHEMA associado à tela de polipropileno (grupo PH) quando utilizados na correção de defeitos criados na parede abdominal de cadelas. Foram utilizadas 12 cadelas sem raça definida, adultas, pesando entre 10 e 20 kg, divididas em dois grupos de seis. Os animais do grupo PP receberam o implante da tela de polipropileno e os animais do grupo PH receberam a tela de polipropileno revestida de hidrogel de poliHEMA em substituição ao músculo transverso do abdome. Seis animais de cada grupo foram submetidos ao procedimento cirúrgico para a retirada das telas aos 30 e 60 dias do pós-operatório. Foram avaliados microscopicamente os fenômenos de reparo tecidual como: reação inflamatória crônica, presença de células gigantes (reação inflamatória crônica granulomatosa tipo corpo estranho), e proliferação conjuntiva. Conclui-se que o hidrogel de poliHEMA como agente de revestimento da tela de polipropileno quando implantado na parede abdominal de cadelas desencadeia maior deposição de colágeno tipo I quando comparado a tela de polipropileno isolada.

The research  concerning lignin in high value applications has increased  during the last years due to its renewability and availability in the black liquor from pulp mills. Today  the major part of kraft lignin found  in the black liquor is used as fuel to gain energy  in the recovery boiler. Lignin functions as natural  glue in plants so that the function of kraft lignin as a phenol replacement in wood adhesives has been researched. Due to lignin's low reactivity the molecule must be modified  prior to use. Demethylation is a method  to increase the phenolic content  in lignin to produce  more reactive  sites. Thiol  mediated  and iodine mediated demethylation was performed. Demethylated lignin was characterized by changes  in phenolic and hydroxylic groups,  molecular  mass, elemental  composition and other  properties  using methods including  UV, SEC and 31 P NMR.   The results showed  a decrease in the phenolic  content  contrary  to the increase  that was expected. Really low yields were also gained  which makes the results non-representative. Size evaluation showed  that the percentage of high molecular  content  in the demethylated lignin sample  had increased,  which  point towards the loss of low molecular mass fractions.  Due to demethylation lignin may have been more hydrophilic and soluble  in DMF and water. In addition  to this bond cleavage  may have produced  smaller  fragments which also increase  the solubility. The results point towards  the loss of smaller  fragments in the DMF and water phases.   The applied demethylation methods were evaluated  in context of green chemistry. Production, waste,  involving chemicals and efficiency were discussed  and analyzed. The applied demethylation methods  use DMF as solvent  which  is not a green alternative, greener solvents such as water or other energy  adding  methods  could  be used to make the process  greener.  The use ofNaOMe produces  methanol  as a byproduct  which could be eliminated by using NaOH, future studies  on the efficiency of the bases in the needs to be done.   Nature science  has a reputation  of being hard and firm. By bringing  in social  issues in science education new ways of looking  at science  opens  up. A social problem  and at the same time an environmental problem  in today's  society  is the large plastic mountain in the Pacific Ocean. An educational material  of the "Samhallsfragor med Naturvetenskapligt Innehiill",SNI, (Societal  issues with scientific content)  principle  has been evaluated with respect  to the abilities that can developed together  with whether  students  increase  their science  knowledge through  this. The study showed  that students  can develop  almost  all abilities  described  in the curriculum and their knowledge in science  by this type of material. Keywords Biomaterial, lignin reactivity,  thiol mediated  demethylation, iodine mediated demethylation, green chemistry, SNl-fall. / Forskning kring lignin i produkter har ökat under de senaste åren på grund av lignins fornyelsebarhet och tillganglighet i svartluten från massabruken. Idag används den största delen av sulfatligninet från svartluten som bränsle for att producera energi i sodapannan. Lignin fungerar som ett naturligt lim i växter och på grund av detta undersöks funktionen av kraftlignin som fenolersättning i trälim. Med anledning av ligninmolekylens låga reaktivitet behover lignin modifieras fore användning i produkter. Demetylering är en metod för att öka fenolhalten i lignin och skapa en högre reaktivitet. I denna studie utfördes Tiolmedierad och jodidmedierad demetylering. Det demetylerade ligninet utvärderades med avseende på forändringar i  fenol-och hydroxylgrupper, molekylvikt, elementarsammansättning och andra egenskaper med hjälp av olika metoder,inklusive UV, SEC och 31 P NMR.   Resultaten visade en minskning i fenolinnehall  i motsats till den ökning som förväntades. Riktigt låga utbyten påvisades också vilket gör att resultaten inte är representativa. Storleksutvärdering  visade att andelen med högt molekylviktsinnehåll i det demetylerade ligninproven hade ökat, vilket pekar mot förlust av lågmolekylära fraktioner. På grund av demetyleringen kan ligninet ha blivit mer hydrofilt och lösligt i DMF och vatten. Utöver detta kan bindningsklyvning ha skapat mindre fragment som också ökat lösligheten. Resultaten pekar mot förlust av mindre fragment i DMF-och vattenfaserna.   De tillämpade demetyleringsmetoderna  utvärderades med avseende på grön kemi. Produktion, avfall, kemikalier och effektivitet diskuterades och analyserades. De tillämpade demetyleringsmetoderna  använder DMF som lösningsmedel, vilket inte är ett grönt alternativ. Grönare lösningsmedel såsom vatten, eller andra typer av energitillsättning, kan användas för att göra processen miljövänligare. Användandet av NaOMe i den thiolmedierade demethyleringen skapar metanol som en biprodukt vilket kan bytas ut mot vatten om NaOH istället används. Vidare studier behöver göras för att undersöka de båda baserna effektivitet.   Naturvetenskapen har ett rykte om att vara hård och fast. Genom att föra in sociala frågor i den naturvetenskapliga utbildningen kan nya sätt att se på vetenskapen skapas. Ett samhälls problem och samtidigt ett miljöproblem i dagens sämhalle är det stora plast berget i Stillahavet. Ett undervisningsmaterial för"Samhällsfrågor Med Naturvetenskapligt Innehåll", SNI, principen har utvärderats med avseende på vilka förmågor som kan tränas tillsammans med huruvida eleverna kan öka sin vetenskapliga kunskap. Studien visade att eleverna kan utveckla nästan alia formågor som beskrivs i läroplanen och sina kunskaper inom naturvetenskapen genom denna typ av utbildningsmaterial.   Nyckelord Biomaterial, ligninreaktivitet, tiol medierad demetylering, jodmedierad demetylering,grön kemi, SNI-fall.

Denna studie undersöker möjligheten att ta fram en mer hållbar och cirkulär armatur i ett samarbete med ateljé Lyktan i Åhus, där utgångspunkten är deras armatur RIFF pendel. Studien utgår huvudsakligen utifrån ett materialperspektiv där en översyn av delar inom armaturen ses över för att skapa en cirkularitet kring produkten. Teorin har sin utgångspunkt inom design för hållbar utveckling där förhållandet till cirkulär ekonomi ligger i fokus, detta för att utforska med ett materialdrivet designperspektiv utgå från själva materialet med krav som en huvudkaraktär i utformandet. För att uppnå ett resultat och slutsats utförs en förstudie som research metod och en designspecifikation skapas för att sammanställa allt som armaturen ska klara av att lösa och bidra med. Researchen följs upp av en designprocess för att undersöka och konkretisera de designmål och kriterier som produkten behöver uppnå. Studien ger förslag till ateljé Lyktan i form av en skärm och och uppgradering av befintliga ljusmotorn för RIFF armatur med ett cirkulärt material från en förnybar resurs. / This study examines the possibility of developing a more sustainable and circular luminaire in collaboration with ateljé Lyktan in Åhus, based on their RIFF pendant luminaire. The study primarily focuses on a material perspective, reviewing parts within the luminaire to create circularity around the product.  The theory is based on design for sustainable development where the relationship to the circular economy is in focus, this to explore with a material driven design perspective starting from the material itself with requirements as a main character in the design. To achieve a result and conclusion, a preliminary study is conducted as a research method, and a design specification is created to compile all the aspects that the luminaire needs to solve and contribute to. The research is followed by a design process to investigate and concretize the design goals and criteria that the product needs to achieve. The result of this study provides suggestions to ateljé Lyktan in the form of a shade and an upgrade of the existing light engine for the RIFF luminaire with a circular material from a renewable resource.

Calcific aortic valve disease (CAVD) is associated with significant cardiovascular morbidity. While late-stage valve disease is well-described, there remains an unmet scientific need to elucidate early pathobiological processes. In CAVD, pathological differentiation of valvular interstitial cells (VICs) and lesion formation occur focally in the fibrosa layer. This VIC pathological differentiation has been shown to be influenced by matrix stiffness in vitro. However, little is known about the focal layer specific mechanical properties of the aortic valve in health and disease and how these changes in matrix moduli may influence VIC pathological differentiation in vivo. In this thesis, micropipette aspiration (MA) was shown to be capable of measuring the mechanical properties of a single layer in multilayered biomaterial or tissue such as the aortic valve, if the pipette inner diameter was less than the top layer thickness. With MA, the fibrosa of normal porcine aortic valves was significantly stiffer than the ventricularis; stiffer locations found only within the fibrosa were comparable to stiffnesses shown in vitro to be permissive to VIC pathological differentiation. Early CAVD was induced in a porcine model, which developed human-like early CAVD lesion onlays. Extracellular matrix remodeling occurred in the absence of lipid deposition, macrophages, osteoblasts, or myofibroblasts, but with significant proteoglycan-rich onlays and chondrogenic cell presence. These early onlays were softer than the collagen-rich normal fibrosa, and their proteoglycan content was positively correlated with Sox9 chondrogenic expression, suggesting that soft proteoglycan-rich matrix may be permissive to chondrogenic VIC differentiation. The findings from this thesis shed new light on early disease pathogenesis and improve the fundamental understanding of aortic valve mechanics in health and disease.

Human induced pluripotent stem cells (hiPSCs) have two main properties: pluripotency and self-renewal. Physical cues presented by biomaterial scaffolds can stimulate differentiation of hiPSCs to neurons. In this work, we develop and analyze a mathematical model of aggregate growth and neural differentiation on melt electrospun biomaterial scaffolds. An ordinary differential equation model of population size of each cell state (stem, progenitor, differentiated) was developed based on experimental results and previous literature. Analysis and numerical simulations of the model successfully capture many of the dynamics observed experimentally. Analysis of the model gives optimal parameter sets, that correspond to experimental procedures, to maximize particular populations. The model indicates that a physiologic oxygen level (~5%) increases population sizes compared to atmospheric oxygen levels (~21%). Model analysis also indicates that the optimal scaffold porosity for maximizing aggregate size is approximately 63%. This model allows for the use of mathematical analysis and numerical simulations to determine the key factors controlling cell behavior when seeded on melt electrospun scaffolds. / Graduate

Chronic obstructive pulmonary disease (COPD) including emphysema is a devastating condition, increasing in prevalence in the US and worldwide. There remains no cure for COPD, rather only symptomatic treatments. Due to unique challenges of the lung, translation of therapies for acute lung injury to target chronic lung diseases like COPD has not been successful. We have been investigating lung derived extracellular matrix (ECM) hydrogels as a novel approach for delivery of cellular therapies to the pulmonary system. During the course of this work we have developed and characterized a lug derived ECM hydrogel that exhibits “injectability,” allowing cells or dugs to be delivered in a liquid and encapsulated at body temperature. The hydrogel self assembles in <5 minutes and achieves mechanical stiffness similar to other soft tissue ECM hydrogels. The hydrogel can support 3D cell growth and encapsulated cell viability. Encapsulated hMSCs can also still be activated by simulated inflammatory environments. Naïve mouse macrophages exposed to the fully formed gel were not significantly induced to express markers for pro or anti-inflammatory polarized phenotypes, but increased expression for several secreted inflammatory mediators was observed. We also investigated a novel approach for preparing and solubilizing the isolated ECM proteins, using digestion time as a variable for controlling hydrogel density (interconnectivity), mechanical stiffness, component protein size distribution, and cell behavior on fully formed gels. The potential future impact for the presented research includes optimization for future animal studies, expansion to additional applications, and the development of new derivative materials.

La résorption post-extractionnelle est de nos jours une conséquence inéluctable après avulsion. Cette résorption, lors d'une réhabilitation prothétique sur implants, peut avoir des conséquences néfastes tant dans le résultat esthétique que fonctionnel. Les techniques de régénération pré-implantaire (technique dérivée de la régénération tissulaire guidée) par l'emploi d'autogreffe, de xénogreffe ou encore d'allogreffe associée ou non à une membrane ont montré des bénéfices quant à la préservation du volume osseux. Les délais d'ostéointégration ayant été de nos jours réduits avec un taux de survie implantaire satisfaisant, la technique d'extraction/implantation immédiate a été envisagée dans le but d'éviter la perte osseuse post-extractionnelle et réduire le temps de traitement. Toutefois, les études menées chez le chien par différents auteurs ont montré que cette technique ne permettait en aucun cas d'éviter la resorption post-extractionnelle. La mise en place précoce d'un implant dans une alvéole déshabitée permet seulement de limiter cette dernière. Le but de note étude animale a donc été, dans les cas d'extraction/implantation immédiate, d'évaluer la perte osseuse obtenue au travers des résultats tomodensitométriques et histovolumétriques, perte osseuse comparée, à celle mesurée dans les chirurgies de comblement ainsi que dans les chirurgies régénératives avec membranes positionnées en supra ou intra-alvéolaire. Nous avons également souhaité évaluer l'intérêt de la régénération osseuse guidée dans la préservation du volume osseux lorsqu'une prothèse sur implant est envisagée. Notre choix s'est porté sur une membrane collagénique résorbable qui ont montré au travers de nombreuses études certains avantages : biocompatibilité satisfaisante, exposition n'engendrant pas un échec de la chirurgie et enfin une résorbabilité évitant une chirurgie de dépose. Concernant le matériau de comblement, nous avons opté pour une allogreffe corticale afin d'évaluer la cicatrisation osseuse obtenue, la résorbabilité du matériau et la qualité de l'interface os/implant. Dans une première partie, nous ferons un rappel sur le tissu osseux et son remodelage après avulsion. La seconde partie sera consacrée aux techniques de préservation du volume osseux, la troisième partie faisant le point sur la technique d'extraction/implantation immédiate d'un point de vue cicatrisation osseuse. Enfin la quatrième et dernière partie sera consacrée à l'étude animale. / Post-extraction resorption is nowadays an inevitable consequence of teeth extraction. This loss, during prosthetic implant rehabilitation, strongly affects aesthetic and functional results.Guided bone regeneration, issue from the guided tissular regeneration, using autogenous bone, xenograft or still allograft associated or not with a barrier membrane shows benefits in the conservation of bone volume.The delays of osteointegration having nowadays been reduced with a good rate of implant survival; immediate extraction-implantation is supposed to avoid post-extraction resorption and to reduce overall treatment time. However, animal studies from many authors showed that this technique cannot avoid the post-extraction resorption. The immediate implantation only allows to reduce it.The purpose of our animal study was to estimate the bone loss for immediate extraction-implantation technique through the histotomodensimetric and histovolumetric measurements. Bone loses were compared for allogenic bone grafting associated or not with supra or intra alveolar barrier membranes. We investigate also the benefits of guided bone regeneration in the preservation of bone volume for delayed implantation. The parameters followed were the alveolar bone loss, the resorbability of the material and the quality of bone/ implant interface. We selected absorbable collagenic barrier membrane which have shown in numerous studies many advantages: good biocompatibility, exposure don't challenge clinical results and resorbability avoiding an additionnal removal surgery. Concerning the bone grafting material, we opted for a cortical allograft. In the first chapter, we made a review of the bone histology and physiology and of its remodeling after extraction. The second chapter is dedicated to alveolar bone preservation techniques and in the third chapter we reviewed immediate extraction-implantation surgical techniques from the point of view of bone healing. Finally the fourth part of our thesis is dedicated to the presentation and analysis of our animal study.

Spider silk is a material that both has impressive mechanical properties and is also environmentally friendly. Though there are limitless potential engineering applications for such materials, industrial production of spider silk has proven to be challenging. Farming silk from spiders, as is done with silkworms, is not a viable option for large-scale production of spider silk due to the venomous and predatory nature of spiders. Here, an attempt is made to express synthetic spider silk minifibroins heterologously in Escherichia coli, to purify the recombinant spidroins from cell lysate, and to spin them into artificial fibers through a biomimetic process. Silk minifibroins were designed to be similar to Major Ampullate Spidroin 1 from Latrodectus hesperus. Synthetic fibers were examined by scanning electron and light microscopy, and their mechanical properties were tested by a tensometer. Properties of synthetic silk were compared to those of native dragline silk from the same species from which their design was inspired, revealing synthetic silk fibers with lower breaking stress and breaking strain.

Depuis une dizaine d'année, le rôle des biofilms dans la résistance aux antibiotiques et à la réponse immunitaire a été mis en évidence dans les infections chroniques. Les plaies chroniques possèdent ces mêmes particularités de résistance aux divers traitements. La formation de biofilm dans les plaies induit une protection des bactéries qui participe potentiellement à la chronicité et est responsable de l'inefficacité des soins. Le but de ma thèse est de concevoir un biogel actif contre les biofilms pouvant être présents dans les plaies chroniques.Nous avons développé un gel de gélatine innovant contenant divers agents anti-biofilms et permettant l'éradication des bactéries pathogènes. Ces gels sont des solides mous composés d'une phase liquide emprisonnée dans un réseau de biopolymères. Biocompatibles et biorésorbables, ils présentent des avantages pour une utilisation en tant que biomatériaux pour la santé. Il est possible d'y inclure des molécules qui vont ensuite diffuser vers le milieu extérieur. Pour mieux appréhender cette cinétique de diffusion, nous avons étudié le relargage de molécules modèles de différents poids moléculaires et de différentes charges.La stratégie anti-biofilm adoptée consiste à prévenir la colonisation bactérienne, déstabiliser le biofilm et éradiquer les bactéries pathogènes de la plaie (Diminution de la biomasse d'au moins 5 logarithmes). Pour développer ce système, 3 types de molécules ont été combinées : un antiseptique commercial, utilisé dans le cadre des soins des plaies chroniques, un chélateur d'ions actifs contre les MMPs surexprimées dans les plaies et une protéase capable de dégrader la matrice du biofilm. Cette étude a été réalisée sur des biofilms mono-espèce de P. aeruginosa et S. aureus, bactéries pathogènes fréquemment retrouvées dans les plaies chroniques. La combinaison des principes actifs a été testée en solution, en contact direct avec le biofilm. Puis, les agents ont été encapsulés dans un biogel. Nous avons étudié à la fois les propriétés viscoélastiques de ces gels mais aussi leur efficacité contre un biofilm, comparé au traitement non encapsulé. Lors de ce travail, nous avons élaboré un gel manipulable capable d'éradiquer un biofilm mono espèce ou multi espèces, constitué de souches de laboratoire ou de souches cliniques issues de plaie chronique. / Over the past 10 years, researchers have highlighted the role of biofilms on resistance to immune response and antibiotics treatments of chronic infections.Chronic wounds share these characteristics as they are resistant to care treatments. The possible biofilm formation in wound can protect bacteria participating to the chronicity and the resistance to wound care treatment. The aim of this thesis is to conceive a biogel against biofilms in chronic wounds.We have developed an innovative gelatin gel containing various anti-biofilm agents able to eradicate pathogenic bacteria biofilm. This gel is soft matter composed of a liquid phase entrapped in a biopolymer network. It is biocompatible and bioresorbable; these properties are necessary for a biomaterial. The gel has the capacity to deliver molecules with controlled release. We have studied the release of model molecules with different charges and weights.The anti-biofilm strategy consisted in preventing bacterial colonization, disrupting the biofilm and eradicating pathogen bacteria in wound (a decrease biomass of at least 5 log reductions). The system developed consisted in the combination of three different types of molecules: a commercial antiseptic usually applied in chronic wound care, an ion chelator active against MMPs which are over-expressed in chronic wounds and a protease which can disrupt the matrix of the biofilm.The study has been carried out on mono-species biofilms synthesized in vitro, with P. aeruginosa and S. aureus, two pathogenic bacteria frequently encountered in chronic wounds. The combination of the active agents was tested in solution or in directly contact with the biofilm. Then molecules were entrapped in the biogel. The viscoelastic properties of the gel were studied and the efficacy of the entrapped treatment compared to that of the solution. A handeable and efficient biomaterial has been elaborated during this study. It is able to eradicate mono – and multi- species biofilms from both laboratory and clinical bacterial strains.