Estudos sobre cronificação têm se mostrado cada vez mais importantes, visto que, tanto na medicina humana, quanto na medicina veterinária, tem sido comum a ocorrência de lesões crônicas, que muitas vezes apresentam dificuldade de cicatrização com terapia convencional. Por este motivo, o presente trabalho tem por objetivo estabelecer modelo de ferida crônica em ratos Wistar, com o uso de agentes químicos, comumente utilizados na rotina clínica como antissépticos, em doses consideradas tóxicas ao leito da ferida. Para isso, foram utilizados 48 ratos Wistar, machos, divididos em quatro grupos de 12 animais cada. (Controle, Polivinilpirrolidona - PVPI 1%, Clorexidina 1% e H2O2 35%). Os animais foram submetidos a anestesia inalatória e sofreram lesão circular de 1cm de diâmetro, confeccionada com o uso de trépano corneal. Foram realizadas duas feridas simétricas paralelas e em seguida à confecção iniciou-se a aplicação tópica dos agentes químicos, com auxílio de pipeta de 50μl, sendo instilados duas vezes ao dia, durante 15 ou 30 dias. As avaliações macroscópicas das feridas induzidas cirurgicamente eram realizadas a cada dois dias, através de medição com paquímetro, além de observação quanto a presenças de sangramentos e outras secreções. Foram avaliadas também através de histologia e imuno-histoquímica. Como resultados o grupo PVPI teve maior taxa de contração, cicatrizando em menor tempo que o grupo controle, embora essa diferença de tempo não tenha sido significativa estatisticamente; apesar das feridas se apresentarem cicatrizadas macroscopicamente, à avaliação histológica foi possível perceber que haviam alterações, dignas de processo cicatricial em curso; o grupo H2O2 proporcionou resultados positivos perante aquilo que foi proposto. Sugere-se que novos estudos sejam realizados, com o H2O2, nos quais os períodos de uso do agente sejam prolongados, superiores aos usados no presente estudo, utilizando ainda material de silicone, fixado nas bordas da ferida, com o intuito de evitar cicatrização por contração. Sugere-se também o uso de doses elevadas de analgésicos durante todo o tempo de experimento. / Research on chronic lesions have been of increased interest in both human and veterinary medicine, as different conditions can delay and lead to difficulties on wound healing, even after conventional therapy has been instituted. Although there are several reports on experimental models for the study of acute wound healing, the establishment of chronic lesions using chemical agents, for scientific purposes, is scarce. This study pursued the development of a chronic skin wound model with chemical substances routinely used as antiseptics, in concentrations considered detrimental to injured tissue. For that, forty-eight Wistar rats were divided in four groups of 12 animals each, for of one of the topical treatments: povidone-iodine solution, 1% chlorhexidine, 35% hydrogen peroxide (H2O2), and control with 0.9% saline solution (NaCl). Under general anesthesia, two circular full skin defects, with 1cm diameter, were produced (with a corneal trephine) in the dorsal cervical region of all the animals. Immediately after the incisions, 50μl of one of the treatments were administrated twice daily, for either 15 or 30 days. Macroscopic evaluations were performed every other day, recording wound size (with a pachymeter) and occurrence of bleeding or exudates. Microscopically, at day 15 or 30, histologic and immunohistochemical studies were carried out with the complete removal of the wound or cicatricial region. Macroscopically, the povidone-iodine group showed faster wound contraction and healing rate than the control, yet, this difference was not statistically significant. Although, under clinical observation, the incised regions presented scar tissue, the histopathological evaluation of the respective specimens showed uncompleted healing process features. The hydrogen peroxide demonstrated promising results to the proposed intent. However, a bigger sample is needed to ascertain the found evidences. Furthermore, studies with longer or more frequent periods of substance exposure, along with devices to circumvent wound contraction and higher doses of analgesics, are recommended.

Orientador: Cristina Pontes Vicente / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-18T06:17:17Z (GMT). No. of bitstreams: 1 Carneiro_GianeDaniela_M.pdf: 3364731 bytes, checksum: 2f5ed663ad69815d0943761ec70e6408 (MD5) Previous issue date: 2011 / Resumo: As células progenitoras endoteliais (CPEs) foram descritas por Asahara et al. (1997), isoladas a partir do sangue periférico e são células originadas da medula óssea. Estas células podem ser reconhecidas pela expressão de marcadores como o CD34, CD133, VEGFR2 e o CD31, pela capacidade de internalização de acLDL e de formar estruturas semelhantes a vasos quando cultivas em matrizes tridimensionais. Quando ocorrem lesões endoteliais, elas podem ser mobilizadas da medula migrando para o sangue periférico e atuar no local da lesão arterial, podendo se diferenciar em células endoteliais maduras e promover a re-endotelização do vaso lesionado. Contudo, estas células estão presentes na medula óssea e no sangue periférico em quantidade muito pequena, 0,1 e 0,01% do total de células respectivamente, o que leva diversos grupos de pesquisa buscarem selecionar e cultivar estas CPEs visando aumentar seu número para melhor caracterizá-las in vitro e in vivo. Em nosso trabalho, buscamos estabelecer um meio de cultura capaz de sustentar o crescimento, proliferação e diferenciação das células progenitoras endoteliais isoladas a partir de medula óssea de camundongos C57bl/6, e de caracterizar seus vários estágios de diferenciação destas células em diferentes tempos de cultura. Para tal, células mononucleares foram isoladas da medula de camundongos C57bl/6 por gradiente de Ficoll-Paque PLUS e cultivadas por 3, 7 e 14 dias em meios de cultura diferentes acrescidos de diferentes fatores de crescimento (VEGF, IGF, bFGF e EGF) com concentrações variadas. Dentre todos os meios testados, o DMEM1-M1 (DMEM com vermelho de fenol acrescido de VEGF, IGF e bFGF) foi o que apresentou melhores resultados para os ensaios de proliferação, de viabilidade celular por DAPI, Azul de Tripan e MTT. A partir deste meio foram realizados testes para verificar a expressão de marcadores celulares (CD133, CD34, VEGFR-2 e CD31) por imunocitoquímica, imunofluorescência, Western Blotting e citometria de fluxo. Os resultados de imunocitoquímica e imunofluorescência foram positivos para todos os marcadores, em todos os períodos analisados. A análise por Western Blotting confirmou a expressão destes marcadores, com aumento na expressão de 3 para 7 dias de cultura. Por citometria de fluxo analisamos o perfil destas células em cultura de 7 dias comparando com as células in vivo, e conseguimos visualizar um aumento principalmente na freqüência de células que expressam VEGFR-2, um indicativo de que o meio utilizado está selecionando células progenitoras. A internalização de acLDL que também indica CPEs foi positiva após 7 e 14 dias. As células cultivadas em Matrigel® formaram estruturas semelhantes a vasos após 7 dias de cultura. Nossos resultados indicam que fomos capazes de estabelecer um meio de cultura eficiente na seleção e proliferação de CPEs, inibindo sua diferenciação inicial em células endoteliais, o que nos permitirá utilizar esta técnica de cultura para expandir o número de CPEs obtidas da medula óssea e poder utilizá-las no tratamento de lesões arteriais e em diferentes processos de terapia celular / Abstract: Endothelial progenitor cells (EPCs) were described by Asahara et al. (1997) isolated from peripheral blood, these cells are derived from bone marrow. EPCs can be characterized by the expression of cellular markers like CD34, CD133, VEGFR2 and CD31, internalization of acLDL and formation of structures similar to vessels when culture in tridimensional matrices. In the presence of endothelial lesion, they can be mobilized from bone marrow, migrating to peripheral blood and subsequently the endothelial lesion site. They can differentiate into mature endothelial cells and participate in the re-endothelization of the damaged vessel. However these cells are rare in bone marrow and peripheral blood 0,1 and 0,01%, respectively, several research groups are trying to develop strategies to isolate and cultivate these cells to better determine their characteristics in vitro and in vivo. In our study we tried to establish a culture medium able to sustain growth and proliferation of EPC obtained from C57bl/6 mice bone marrow and characterize the stages of differentiation that they could present in different times of culture. In order to do it, we isolated mononuclear cell from bone marrow using a Ficoll-Paque PLUS gradient and cultivated then for 3, 7 and 14 days using culture mediums with different compositions and concentrations of growth factors (VEGF, IGF, bFGF, EGF). Cellular growth determined by DAPI, trypan blue counting and MTT was more significant with the medium we named DMEM1-M1 (with VEGF, IGF and bFGF). Results obtained with immunocitochemistry and immunofluorescence with this medium was positive in all culture times. Western blotting demonstrated the expression of VEGFR2, CD34 and CD133 in 3 e 7 day, with a litte increase after 7 days. Flow citometry analysis of cells after 7 days in culture demonstrated an increase in cells expressing VEGFR2, indicating the selection of EPC with this medium. Internalization of acLDL and formation of structures similar to vessels were observed after 7 and 14 days in culture and confirms differentiation of mononuclear cells into EPC. So, in conclusion, our results indicate that we developed a culture medium able to sustain proliferation and differentiation of EPCs, inhibiting their terminal differentiation what will allow us to use this culture technique to increase the number of EPC from bone marrow obtained and in the future use these cells in the treatment of arterial lesions in different process of cellular therapy / Mestrado / Biologia Celular / Mestre em Biologia Celular e Estrutural

O efeito dos hormônios glicocorticóides (GC) de suprimir o crescimento celular é exercido através de cascatas celulares nas quais a transcrição de genes de resposta primária, mediada direta ou indiretamente pelo receptor de GC, regulam a transcrição e a atividade de um conjunto de genes, incluindo fatores importantes para a progressão no ciclo celular. Entretanto, a conexão funcional entre diversos dos genes ativados ou inibidos por GC e a inibição da proliferação de determinados tipos celulares ainda não é completamente conhecida. Nosso laboratório isolou a variante ST1, a partir da linhagem C6 de glioma de rato, utilizando-a como modelo de estudo do mecanismo de ação de GC como agentes anti-tumorais. O tratamento com GC confere, às células ST1, um crescimento totalmente dependente de soro e ancoragem, morfologia em cultura semelhante à de fibroblastos normais e incapacidade de gerar tumor em camundongos da linhagem \"nude\", caracterizando uma completa reversão fenotípica tanto in vitro como in vivo. Como abordagens para o entendimento do mecanismo molecular da ação de GCs, o laboratório vem buscando a clonagem de produtos gênicos diferencialmente expressos através do uso de técnicas que permitam a análise da abundância relativa dos mRNAs, e mais recentemente, empregando-se a análise da abundância relativa das proteínas através da eletroforese bidimensional (2D-PAGE). As seqüências isoladas por estas metodologias são alvos potenciais para uma posterior análise funcional. Os objetivos gerais deste trabalho foram: a) identificar genes que estão diferencialmente expressos durante a reversão fenotípica das células ST1 induzida por GC, através da análise proteômica (2D-PAGE e espectrometria de massas) e b) determinar a função de um dos genes (Ciclina G) identificado anteriormente no laboratório como sendo induzido durante o tratamento das células ST1 com GC. A metodologia empregada se baseou na comparação dos perfis 2D de proteínas nucleares das células ST1 tratadas ou não (controle) com GC por 5 e 24h. Após análise de imagem, 33 polipeptídios foram considerados como diferencialmente representados após 5h de tratamento, 16 dos quais foram também identificados após 24h de tratamento. Seis destes polipeptídios foram identificados através da análise dos seus perfis de digestão tríptica (PMF). Evidências obtidas por ensaios de Western blot sugerem que um destes polipeptídeos, a Anexina 2 (ANX2), possui a sua localização sub-celular modulada pela ação de GC nas células ST1. A análise do papel da Ciclina G na reversão fenotípica tumoral-normal das células ST1 induzida por GC, foi feita através da sua super-expressão nestas células, utilizando um sistema retroviral, e avaliando-se os efeitos desta super-expressão sobre a resposta das células ST1 a GC, através de ensaios de curva de crescimento e citometria de fluxo. Os dados sugerem que a super-expressão da Ciclina G nas células ST1 intensifica e prolonga o efeito de GC nestas células. / The glucocorticoid (GC) growth suppression response is controlled through cellular cascades in which the transcription of primary response genes regulates the expression and activity of a diverse set of genes including important factors for cell cycle progression. However, the functional connection between the GC-regulated transcriptional events and cell cycle arrest of determined cells is poorly understood at the molecular level. In this context, our lab has isolated the ST1 variant of the C6 rat glioma cell line to study the mechanism of action of GC as anti-tumor agents. GC treatment leads ST1 cells to a dramatic tumoral to normal phenotypic reversion, characterized by inhibition of their growth rate in monolayer, loss of their ability to form colonies in semi-solid medium and to induce tumor formation in nude mice, and morphological changes (flattening). As part of the strategy to understand the anti-tumor action of GC, differentially represented proteins, associated with the phenotypic reversion displayed by ST1 cells have been isolated through mRNA-based blind cDNA cloning and, more recently, by two dimensional electrophoresis (2D-PAGE). The sequences isolated by these two methodologies are potential targets for functional analysis. In the present study, we aimed at a) identifying genes which are differentially expressed during the GC-induced phenotypic reversion of ST1 cells, using the proteomic approach (2D-PAGE and mass spectrometry) and b) determining the functional role of a gene (Cyclin G) which had previously being identified as being induced during GC-treatment of the ST1 cells. The analytical methodology used relied on the comparison of sets of 2D nuclear protein profiles of ST1 cells, maintained in the absence (control) and in the presence of GC for 5 and 24h. After image analysis and visual validation, 33 polypeptides were considered as differentially represented 5 h after treatment, 16 of which were also differentially represented after 24 h. Six of those polypeptides were identified by peptide mass fingerprinting (PMF). Evidence obtained by Western blot analysis indicates that one of those polypeptides, Annexin 2 (ANX2), has its sub-cellular location modulated by GC-treatment of ST1 cells. The role of Cyclin G in the tumoral to normal phenotypic reversion induced by GC in ST1 cells was analyzed by over-expression of Cyclin G using a retroviral system and evaluation of the effects of this over-expression over ST1 cells response to GC, by growth curve and flow cytometry assays. The data suggest that Cyclin G over-expression leads to a more intense and prolonged effect of GC on ST1 cells.

Der "klassische" Importweg von Proteinen wie Transkriptionsfaktoren, Kernrezeptoren oder viralen Proteinen in den Zellkern erfolgt in Abhängigkeit der Importine alpha und beta. Während nur ein Importin beta existiert, waren zu Beginn der Arbeiten zwei humane alpha-Importine bekannt. In der vorliegenden Arbeit wird die Identifikation, Klonierung und funktionelle Charakterisierung von vier neuen humanen alpha-Importinen beschrieben. Anhand ihrer Primärstruktur wurden die sechs alpha-Importine in drei Subfamilien unterteilt. Um die Hypothese zu testen, dass die verschiedenen Importin alpha Isoformen spezifische Funktionen ausüben und sich nicht vollständig gegenseitig ersetzen können, wurde zunächst ihre Expression auf RNA- und Proteinebene analysiert. Hier ließen sich differentielle Expressionsmuster in verschiedenen humanen Zellen und Geweben nachweisen. In vitro Analysen mit rekombinant exprimierten und aufgereinigten Proteinen deuteten daraufhin, dass die neu identifizierten Isoformen tatsächliche Importfunktion besitzen, dass sich jedoch die verschiedenen alpha-Importine in ihren Substratspezifitäten unterscheiden. Verschiedene neue Substrate der alpha-Importine wurden identifiziert und deren Importwege im Detail analysiert. Unterschiede in der Regulation der Expression der alpha-Importine in Abhängigkeit von Zellproliferation, Zelldifferenzierung bzw. in unterschiedlichen Diabetesmodellen der Ratte deuteten ebenfalls auf spezifische Funktionen der verschiedenen Isoformen hin. Die spezifische Inhibition der Importin alpha Expression in kultivierten HeLa-Zellen mittels RNA-Interferenz führte bei den meisten Isoformen zu einer ausgeprägten Inhibition der Zellproliferation, wodurch erstmals der Nachweis essentieller Funktionen verschiedener alpha-Importine in lebenden humanen Zellen erbracht wurde. In weiterführenden Experimenten sollen die Ursachen für die Inhibition der Zellproliferation bei Importin alpha-Mangel geklärt und die Bedeutung der unterschiedlichen alpha-Importine in vivo weiter analysiert werden. / The "classical" import of proteins like transcription factors, nuclear receptors or viral proteins into the nucleus depends on importins alpha and beta. While only one importin beta is known, two human alpha-importins had been described. In this study the identification, cloning and functional characterisation of four novel human alpha-importins is reported. Based on their primary structures the human alpha-importins can be grouped into three distinct subfamilies. To test the hypothesis that the various alpha-Importins differ in their specific functions and cannot substitute for each other first their expression at the RNA- and protein levels were analyzed. Differential expression patterns in various human cells and tissues could be demonstrated. In vitro analyses using recombinantly expressed and purified proteins indicated, that the newly identified isoforms posses import functions in deed. However, there was evidence for differences in their substrate specific import efficacies. New substrates of the alpha-importins were identified and their import pathways analyzed in detail. Differences in the expression regulation of the alpha-importins depending on cellular proliferation and differentiation as well as in different rat models of diabetes further pointed towards specific functions of the various alpha-importins. Specific expression inhibition of several isoforms of the importin alpha protein family in cultured HeLa-cells using RNA-interference technology caused a strong inhibition of cellular proliferation. This is the first proof for essential functions of different alpha-importins in living human cells. Future experiments shall identify the mechanisms involved in the cellular proliferation inhibition due to importin a deficiency and further analyze the role of the different alpha-importins in vivo.

O efeito dos hormônios glicocorticóides (GC) de suprimir o crescimento celular é exercido através de cascatas celulares nas quais a transcrição de genes de resposta primária, mediada direta ou indiretamente pelo receptor de GC, regulam a transcrição e a atividade de um conjunto de genes, incluindo fatores importantes para a progressão no ciclo celular. Entretanto, a conexão funcional entre diversos dos genes ativados ou inibidos por GC e a inibição da proliferação de determinados tipos celulares ainda não é completamente conhecida. Nosso laboratório isolou a variante ST1, a partir da linhagem C6 de glioma de rato, utilizando-a como modelo de estudo do mecanismo de ação de GC como agentes anti-tumorais. O tratamento com GC confere, às células ST1, um crescimento totalmente dependente de soro e ancoragem, morfologia em cultura semelhante à de fibroblastos normais e incapacidade de gerar tumor em camundongos da linhagem \"nude\", caracterizando uma completa reversão fenotípica tanto in vitro como in vivo. Como abordagens para o entendimento do mecanismo molecular da ação de GCs, o laboratório vem buscando a clonagem de produtos gênicos diferencialmente expressos através do uso de técnicas que permitam a análise da abundância relativa dos mRNAs, e mais recentemente, empregando-se a análise da abundância relativa das proteínas através da eletroforese bidimensional (2D-PAGE). As seqüências isoladas por estas metodologias são alvos potenciais para uma posterior análise funcional. Os objetivos gerais deste trabalho foram: a) identificar genes que estão diferencialmente expressos durante a reversão fenotípica das células ST1 induzida por GC, através da análise proteômica (2D-PAGE e espectrometria de massas) e b) determinar a função de um dos genes (Ciclina G) identificado anteriormente no laboratório como sendo induzido durante o tratamento das células ST1 com GC. A metodologia empregada se baseou na comparação dos perfis 2D de proteínas nucleares das células ST1 tratadas ou não (controle) com GC por 5 e 24h. Após análise de imagem, 33 polipeptídios foram considerados como diferencialmente representados após 5h de tratamento, 16 dos quais foram também identificados após 24h de tratamento. Seis destes polipeptídios foram identificados através da análise dos seus perfis de digestão tríptica (PMF). Evidências obtidas por ensaios de Western blot sugerem que um destes polipeptídeos, a Anexina 2 (ANX2), possui a sua localização sub-celular modulada pela ação de GC nas células ST1. A análise do papel da Ciclina G na reversão fenotípica tumoral-normal das células ST1 induzida por GC, foi feita através da sua super-expressão nestas células, utilizando um sistema retroviral, e avaliando-se os efeitos desta super-expressão sobre a resposta das células ST1 a GC, através de ensaios de curva de crescimento e citometria de fluxo. Os dados sugerem que a super-expressão da Ciclina G nas células ST1 intensifica e prolonga o efeito de GC nestas células. / The glucocorticoid (GC) growth suppression response is controlled through cellular cascades in which the transcription of primary response genes regulates the expression and activity of a diverse set of genes including important factors for cell cycle progression. However, the functional connection between the GC-regulated transcriptional events and cell cycle arrest of determined cells is poorly understood at the molecular level. In this context, our lab has isolated the ST1 variant of the C6 rat glioma cell line to study the mechanism of action of GC as anti-tumor agents. GC treatment leads ST1 cells to a dramatic tumoral to normal phenotypic reversion, characterized by inhibition of their growth rate in monolayer, loss of their ability to form colonies in semi-solid medium and to induce tumor formation in nude mice, and morphological changes (flattening). As part of the strategy to understand the anti-tumor action of GC, differentially represented proteins, associated with the phenotypic reversion displayed by ST1 cells have been isolated through mRNA-based blind cDNA cloning and, more recently, by two dimensional electrophoresis (2D-PAGE). The sequences isolated by these two methodologies are potential targets for functional analysis. In the present study, we aimed at a) identifying genes which are differentially expressed during the GC-induced phenotypic reversion of ST1 cells, using the proteomic approach (2D-PAGE and mass spectrometry) and b) determining the functional role of a gene (Cyclin G) which had previously being identified as being induced during GC-treatment of the ST1 cells. The analytical methodology used relied on the comparison of sets of 2D nuclear protein profiles of ST1 cells, maintained in the absence (control) and in the presence of GC for 5 and 24h. After image analysis and visual validation, 33 polypeptides were considered as differentially represented 5 h after treatment, 16 of which were also differentially represented after 24 h. Six of those polypeptides were identified by peptide mass fingerprinting (PMF). Evidence obtained by Western blot analysis indicates that one of those polypeptides, Annexin 2 (ANX2), has its sub-cellular location modulated by GC-treatment of ST1 cells. The role of Cyclin G in the tumoral to normal phenotypic reversion induced by GC in ST1 cells was analyzed by over-expression of Cyclin G using a retroviral system and evaluation of the effects of this over-expression over ST1 cells response to GC, by growth curve and flow cytometry assays. The data suggest that Cyclin G over-expression leads to a more intense and prolonged effect of GC on ST1 cells.

Disulfide bridges play a significant role in protein-folding as well as en- zyme activity and thus regulate many intra- and extracellular processes. Sulfhydryl oxidase QSOX1 forms S-S bridges de novo, modulating the activity of its substrates and thus directly or indirectly influences vital cel- lular processes. The first part of this thesis focuses on characterization of the role of QSOX1 in cancerogenesis, using breast cancer cell lines (MCF7, MDA-MB-231) and pancreatic cancer cell line (Panc-1), while the second part emphasizes the regulation of QSOX1 expression by different oxygen concentrations. To study the effect of QSOX1 on proliferation of triple-negative cancer cells MDA-MB-231, two genetically modified cell lines - QSOX1-overexpressing and QSOX1 knockout cell lines - were constructed. While increased QSOX1 protein levels do not have a significant effect, the absence of QSOX1 leads to a decreased cellular growth. Lack of QSOX1 also results in visible change in cellular morphology. QSOX1 knockout cells can be mostly characterized as more round-shaped with less noticeable or completely missing lamellipo- dia. This finding is with agreement with to-date literature suggesting that QSOX1 is important not only for cellular proliferation but also for migration and invasiveness. While authenticating the theory of...

Disulfide bridges play a significant role in protein-folding as well as en- zyme activity and thus regulate many intra- and extracellular processes. Sulfhydryl oxidase QSOX1 forms S-S bridges de novo, modulating the activity of its substrates and thus directly or indirectly influences vital cel- lular processes. The first part of this thesis focuses on characterization of the role of QSOX1 in cancerogenesis, using breast cancer cell lines (MCF7, MDA-MB-231) and pancreatic cancer cell line (Panc-1), while the second part emphasizes the regulation of QSOX1 expression by different oxygen concentrations. To study the effect of QSOX1 on proliferation of triple-negative cancer cells MDA-MB-231, two genetically modified cell lines - QSOX1-overexpressing and QSOX1 knockout cell lines - were constructed. While increased QSOX1 protein levels do not have a significant effect, the absence of QSOX1 leads to a decreased cellular growth. Lack of QSOX1 also results in visible change in cellular morphology. QSOX1 knockout cells can be mostly characterized as more round-shaped with less noticeable or completely missing lamellipo- dia. This finding is with agreement with to-date literature suggesting that QSOX1 is important not only for cellular proliferation but also for migration and invasiveness. While authenticating the theory of...

Os frutanos são carboidratos não-disponíveis, classificados como fibra alimentar solúvel e, também, prebióticos. Chegam intactos no intestino grosso (IG) e sofrem fermentação pela microbiota, fornecendo ácidos graxos de cadeia curta (AGCC), gases e biomassa. Os objetivos foram avaliar a fermentação in vivo e in vitro de frutanos da cebola (Allium cepa L.) e seu efeito no intestino grosso de ratos. Durante 38 dias, ratos machos Wistar receberam ração controle (RC) ou suplementada com cebola (10% de frutanos) (RF). Na fermentação in vivo foram avaliados: peso e umidade das fezes, umidade do conteúdo cecal, AGCC, peso total e parede do ceco e pH. Paralelamente, fragmentos do ceco e cólon foram coletados para avaliação morfométrica e proliferação celular. Na fermentação in vitro, as frações indigeríveis das rações (RC e RF) e da cebola foram avaliadas sob diferentes parâmetros, como: pH, AGCC, fermentabilidade e resíduo nãofermentado. A fermentação in vivo causou no grupo frutanos 10%, em relação ao controle, os seguintes efeitos: aumento significante do peso e umidade das fezes, da umidade do conteúdo cecal, do peso e parede do ceco e da concentração de AGCC e diminuição do pH cecal, no grupo frutanos 10% em relação ao controle. Na fermentação in vitro, houve alterações tanto quantitativas como qualitativas de todos os substratos fermentados. De acordo com todas as variáveis analisadas, a RF apresentou maior fermentabilidade quando comparada com a RC. O grupo frutanos 10% apresentou, no ceco, aumento significante no tamanho das criptas, no número de criptas bifurcadas e no índice metafásico em relação ao controle. No cólon não foi evidenciada qualquer mudança microscópica entre os grupos. Os resultados indicam que a ingestão de frutanos causou mudanças significantes nos parâmetros fermentativos, tanto na fermentação in vivo (ratos) quanto na in vitro e na proliferação celular do ceco. A fermentação in vitro mostrou o possível perfil fermentativo dos substratos, a RF teve fermentabilidade maior que a RC. Esse perfil foi confirmado in vivo, onde o grupo frutanos 10% apresentou aumento na produção de AGCC em relação ao controle. O aumento do butirato provavelmente provocou efeito trófico do ceco, evidenciado pelo aumento de peso e de proliferação celular. / Fructans are unavailable carbohydrates, c1assified as soluble dietary fiber and prebiotics. They arrive intact in the large intestine (LI) and are fermented by the microbiota. This fermentation mainly produces short chain fatty acids (SCFA), gases and biomass. The objectives were evaluation of the in vitro and in vivo fermentation of onion fructans (Allium cepa L.) and their effect in the large intestine of rats. Male Wistar rats received, for 38 days, control diet (CD) or onion supplemented diet (10% fructans) (FD). In the in vivo fermentation were evaluated: faeces weight and moisture, moisture of caecal content, SCFA, cecum weight and wall and pH. In parallel, fragments of cecum and colon were collected for morphometric and cellular proliferation evaluation. In the in vitro fermentation, non-digestible fractions of CD and FD were evaluated under different parameters, such as: pH, SCFA, fermentability and non-fermentable residues. In vivo fermentation caused, in the 10% fructans group in relation to the control group, the following effects: a significant increase in faeces weight and moisture, in the moisture of caecal content, in cecum weight and wall, in the concentration of SCFA and a decrease in the caecal pH. The in vitro fermentation showed both quantitative and qualitative changes of all fermented substracts. The FD presented greater fermentability when compared to the CD, according to all variables analyzed. The 10% fructans group presented greater depth and fission of caecal crypts and metaphasic index in relation to the control group. No microscopic changes were noticed in the colon between the groups. The results indicated that the ingestion of fructans caused significant changes on the fermentative parameters, both in vivo (rats) and in vitro fermentation, and on cell proliferation in the cecum. In vitro fermentation indicated a possible fermentative behavior of the substracts and the FD had greater fermentability than the CD. These results were confirmed in vivo, once the 10% fructans group presented an increase in the SCFA production compared to the control group. The increase in butyrate might have caused the trophic effect of the cecum, which was noticed by the increase in weight and cellular proliferation.

Le travail présenté dans cette thèse porte sur l’élaboration de couches minces des biomatériaux biomimétiques nanostructurées par des techniques lasers pulsés et leur évaluation de point de vue physico-chimique et biologique (biocompatibilité, prolifération et différentiation cellulaires avec des biomatériaux). Le but vise à développer une nouvelle méthode de recouvrement d’implants osseux par des techniques laser pulsé avancées (PLD – Pulsed Laser Deposition et MAPLE - Matrix Assisted Pulsed Laser Evaporation). Ces techniques sont utilisées pour la synthèse d’un système biphasique composé de nanoparticules d’hydroxyapatite (HA) associées à des protéines d’adhérence type fibronectine (FN) et vitronectine (VN) déposées sur un substrat type titane. Le support métallique permettra de maintenir la rigidité mécanique, l’hydroxyapatite favorisera la bio-intégration dans le tissu osseux et les protéines accélèreront l’adhérence cellulaire. L’objectif principal est d’accélérer l’adhérence des cellules et formation des tissus sur les implants. Les études de prolifération et différentiation cellulaire suggèrent une prédisposition des cellules à la prolifération induite par les revêtements VN et à la différentiation stimulée par les revêtements FN. Les effets significatifs sur l’attachement, l’adhésion et la prolifération observés dans nos études sont très importants pour la première phase de stabilité mécanique d’un implant. Les couches HA/protéines déposées par laser pourraient permettre de réduire cette phase. / The work presented within the thesis concern the fabrication of biomimetic nanostructured biomaterial thin films by pulsed laser techniques and their evaluation from the physico-chemical and biological (cellular biocompatibility, proliferation and differentiation) points of view. The aim is to develop a new method for coating the osseous implants by advanced pulsed laser techniques (PLD – pulsed laser deposition and MAPLE – matrix assisted pulsed laser evaporation). These techniques are used for the fabrication of a biphasic system composed of hydroxyapatite (HA) nanoparticules associated with large adhesion proteins as e.g. fibronectin (FN) and vitronectin (VN) deposited on a titanium substrate. The metallic substrate will allow keeping the mechanical rigidity; the hydroxyapatite will favor the bio-integration in the osseous tissue while the proteins will accelerate the cellular adhesion. The main objective is to speed up the cellular adhesion and the formation of new tissue around the implant. The cellular proliferation and differentiation studies demonstrated a predisposal to cell proliferation induced by the VN coatings and to cell differentiation by FN. The significant effects on the cell adhesion, proliferation and differentiation observed in our studies are of great importance for the mechanical stability phase of the implant. The layers HA/proteins deposited by laser could reduce the time of this phase.

Methylmercury (MeHg) is a pervasive environmental contaminant with potent neurotoxic, teratogenic and likely carcinogenic activity, for which the underlying molecular mechanisms remain largely unclear. Base excision repair (BER) is important in mitigating the pathogenic effects of oxidative stress, which has also been implicated in the mechanism of MeHg toxicity, however the importance of BER in MeHg toxicity is currently unknown. Accordingly, we addressed this question using: (1) spontaneously- and Simian virus 40 (SV40) large T antigen-immortalized oxoguanine glycosylase 1-null (Ogg1-/-) murine embryonic fibroblasts (MEFs); and, (2) human Ogg1 (hOgg1)- or formamidopyrimidine glycosylase (Fpg)-expressing human embryonic kidney (HEK) cells; reciprocal in vitro cellular models with deficient and enhanced ability to repair oxidatively damaged DNA respectively. When spontaneously-immortalized wild-type and Ogg1-/- MEFs were exposed to environmentally relevant, low micromolar concentrations of MeHg, both underwent cell cycle arrest but Ogg1-/- cells exhibited a greater sensitivity to MeHg than wild-type controls with reduced clonogenic survival and increased apoptosis, DNA damage and DNA damage response activation. Antioxidative catalase alleviated the MeHg-initiated DNA damage in both wild-type and Ogg1-/- cells, but failed to block MeHg-mediated apoptosis at micromolar concentrations. As in spontaneously immortalized MEFs, MeHg induced cell cycle arrest in SV40 large T antigen-immortalized MEFs, with increased sensitivity to MeHg persisting in the Ogg1-/- MEFs. Importantly, cells seeded at a higher density exhibited compromised proliferation, which protected against MeHg-mediated cell cycle arrest and DNA damage. In the reciprocal model of enhanced DNA repair, hOgg1- and Fpg-expressing cells appeared paradoxically more sensitive than wild-type controls to acute MeHg exposure for all cellular and biochemical parameters, potentially due to the accumulation of toxic intermediary abasic sites. Accordingly, our results provide the first evidence that Ogg1 status represents a critical determinant of risk for MeHg toxicity independent of cellular immortalization method, with variations in cellular proliferation and interindividual variability in antioxidative and DNA repair capacities constituting important determinants of risk for environmentally-initiated oxidatively damaged DNA and its pathological consequences.