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Mauris, Jérôme. "Aquifex aeolicus MutS and MutL : insights into the mismatch repair in a hyperthermophilic bacterium." Paris 11, 2009. http://www.theses.fr/2009PA112309.
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La comparaison du génome des bactéries methylant les sites GATC de l’ADN avec celui des bactéries et des eucaryotes ne methylant pas leur ADN aux sites Dam montre que ces derniers n’ont pas d’homologue de MutH, une endonuclease impliquée dans la réparation des mésappariements de bases de l’ADN. Ceci implique une discrimination entre le brin parental et le brin fils, lors de la réplication. Nous avons montré que MutL, chez la bactérie thermophile Aquifex aeolicus (Aae), est comparable à MutLalpha chez les eucaryotes. In vitro, Aae MutL a une activité endonucléase en présence de métaux lourds, stimulée par l’ATP et ne nécessitant par son hydrolyse en ADP. De plus, cette activité est confinée dans le domaine C-terminale de la proteine, dont nous avons caractérisé un motif propre à la famille de répresseurs à la toxine diphtérique (DtxR) et un second motif n’appartenant à aucune famille de protéines connue à ce jour, tous deux impliqués dans l’activité nucléase de Aae MutL. AaeMutL est donc un homologue de la protéine humaine PMS2. Nous avons également caractérisé la protéine Aq_793 et confirmé son activité helicase ATP-dépendente thermostable, qui préfère les substrats ayant une extrémité simple-brin protubérante en 3’, comme UvrD chez E. Coli. Aae MutL est capable de stimuler cette activité avec seulement ce substrat. Cette activation n’est pas dépendante de l’activité endonucléase de MutL. De plus, le domaine C-terminal seul est capable d’activer l’activité hélicase d’Aq_793, phénomène qui n’est pas observé chez E. Coli. Nous avons montré que le système de réparation des mésappariements chez Aquifex aeolicus a des similitudes avec celui d’E. Coli et des eucaryotesThe mismatch repair (MMR) pathway ensures the stability of the genome by correcting the replicative error. In Esherichia coli, MutH discriminates the neosynthetized strand from the template via the hemimethylated GATC (Dam) site. By comparison, eukaryotes and bacteria unable to perform dam methylation do not exibit MutH homologs implying a different method of recognition of the DNA in the MMR pathway. We have shown that MutL from Aquifex aeolicus, a hyperthermophilic bacterium, is similar to eukaryotic MutLalpha. In vitro, Aae MutL is an endonuclease in the presence of heavy metals. This activity is stimulated by ATP binding but not ATP hydrolysis. We also were able to demonstrate that the C-terminal domain (CTD) of MutL was sufficient for MutL endonuclease activity with the characterization of two motifs, the heavy metal binding domain (DtxR) and a yet unknown domain responsible for this activity. Thus, Aae MutL is homologous to human PMS2. We also caracterized the putative helicase Aq_793 and confirmed that the ATP-dependent helicase has a strong preference for a 3’tail ssDNA substrate such as E. Coli UvrD. Moreover, Aae MutL is able to stimulate Aq_793 helicase activity only for this type of substrate in an endonuclease independent fashion. Interestingly, the CTD of Aae MutL was able to stimulate the helicase as well, a phenomenon not observed in E. Coli. We have shown that Aquifex aeolicus MMR pathway has similarities with both E. Coli and eukaryotes
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Mendillo, Marc Laurence. "The MutS and MutL protein families and their role in the initiation of DNA mismatch repair." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2007. http://wwwlib.umi.com/cr/ucsd/fullcit?p3273476.
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Thesis (Ph. D.)--University of California, San Diego, 2007.Title from first page of PDF file (viewed April 9, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.
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Müller, Dell'Oro Magdalena, and Salas Macarena Rodríguez. "Análisis de la inversión de los fondos mutuos : fondos mutuos de capitalización nacional." Tesis, Universidad de Chile, 2015. http://repositorio.uchile.cl/handle/2250/135393.
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Seminario para optar al título de Ingeniero Comercial, Mención Administración y Mención EconomíaEn el presente estudio se realiza un análisis de la selección de cartera de los Fondos Mutuos, particularmente del mercado accionario nacional. El objetivo de este análisis es determinar si la distribución de carteras está relacionada con la situación de mercado actual y a la vez, si ésta asignación de los Fondos Mutuos es eficiente. Las alocaciones y rentabilidad de los Fondos Mutuos de capitalización nacional a lo largo del periodo estudiado nos permitirán tener una visión de cómo se relaciona la selección de carteras con las distintas situaciones de mercado. A lo anterior se suman distintas medidas de eficiencia, como lo son el Alpha de Jensen y Ratio de Sharpe, lo cual agregará profundidad al estudio. Los principales resultados indican que a nivel general la selección de cartera si está relacionada con la situación de mercado actual. Con respecto a la eficiencia los antecedentes estudiados nos permiten concluir que las administradoras si gestionan eficientemente sus carteras en relación a su benchmark. Este análisis es realizado a nivel general de la cartera de los Fondos Mutuos, no debemos olvidar que dentro de esta industria cada uno de los fondos tiene una política de inversión particular. Por otro lado la base de datos utilizada no considera costos de administración.
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Lewis, Christopher Roger. "Chromosomal deletions in Streptococcus mutans." Thesis, University of Newcastle Upon Tyne, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297569.
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Camarena, Rodríguez Martín Eulogio. "Los fondos mutuos de inversión." Bachelor's thesis, Universidad Nacional Mayor de San Marcos, 2011. https://hdl.handle.net/20.500.12672/15109.
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Publicación a texto completo no autorizada por el autorEl primer capítulo, la tesis permite tener una mirada mirada rápida a los aspectos generales de los mercados de valores, del mercado de valores en el Perú y el papel de este frente a la globalización. El segundo capítulo se centra en el tema propiamente dicho: el concepto y clasificación de los mismos, conjuntamente con sus inversiones, composición y valor de la cuota, igualmente el entorno económico en la evolución de los mismos; el papel del Estado en la defensa de los ciudadanos; la visión que aporta la legislación comparada. En el tercer capítulo se analiza el papel de los mismos en el mercado de valores, así como el impacto de los mismos en los mercados de valores mundiales y nacionales. En el cuarto capítulo los sistemas de fondos mutuos y su operatividad, observaremos la situación de los fondos mutuos que operan en el Perú, su constitución y situación actual, su nivel de operatividad: funcionamiento y rendimiento, los fondos mutuos respecto de otros mecanismos de inversión, la naturaleza jurídica de los certificados de participación. En el capítulo quinto se reflexiona acerca del tema de la calidad de los fondos mutuos como medios de representación del capital. En el capítulo sexto se analiza la ley del mercado de valores y de su reglamento respectivo conjuntamente con las perspectivas de reforma de la ley. En el capítulo séptimo se analiza a los fondos mutuos como una alternativa de financiamiento para la pequeña y microempresa en un país como el Perú donde lo que abunda paradójicamente es el dinero, pero faltan aquellos instrumentos en donde se puedan invertir.
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Thevenot, Tracy Lynn. "Aspects of sugar transport via the phosphoenolpyruvate sugar phosphotransferase system of streptococcus mutans /." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq23673.pdf.
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Monteiro-Oliveira, Marcela Pinto 1982. "Estudo da ação antimicrobiana da terapia fotodinamica sobre lesões de carie produzidas in vitro na dentina de dentes bovinos." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/288089.
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Orientador: Marines Nobre dos Santos UchoaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: Durante o processo conhecido como terapia fotodinâmica, a aplicação de fotossensibilizadores associados a uma fonte de luz de comprimento de onda complementar, gera produtos que podem danificar componentes essenciais das células, e causar a morte celular. Dentro desse contexto, a aplicação dessa terapia sobre microrganismos presentes em lesões de cárie é de grande valia, uma vez que poderá reduzir a quantidade de tecido dental a ser removido no tratamento da cárie, diminuir as chances de progressão da doença bem como os riscos de acometimento pulpar do elemento dentário. Assim, o objetivo deste estudo in vitro foi determinar parâmetros para o uso de um diodo emissor de luz (LED) associado ao corante azul de orto toluidina (TBO) na redução da contagem de Streptococcus mutans presentes em lesões de cárie dentinária. Para isto, 72 espécimes de dentina coronária de dentes bovinos foram imersos em cultura contendo Streptococcus mutans para produzir lesões de cárie. Tais espécimes foram divididos aleatoriamente em 6 grupos (n=12): Controle (exposição a NaCl a 0,9% por 5 min); TBO (exposição ao TBO a 0,01% por 5 min); LEDA (exposição ao LED por 4,2 min); LEDB (exposição ao LED por 6,5 min); PDTA (exposição ao corante associado ao LED por 4,2 min) e PDTB (exposição ao corante associado ao LED por 6,5 min). As densidades de energia utilizadas para os tempos de 4,2 e 6,5 min, foram de 166 e 249 J/cm2, respectivamente. Antes e após os tratamentos, amostras de tecido dentinário cariado foram coletadas e analisadas microbiologicamente, por meio da contagem das unidades formadoras de colônia (UFC) de S. mutans. A profundidade das lesões de cárie produzidas pelo modelo microbiológico utilizado foi determinada por meio da microscopia de luz polarizada. Foram utilizados os testes ANOVA/Tukey para comparar os valores de log redução dos grupos (a=5%). Observou-se redução significativa de S. mutans nos grupos em que aplicou-se TBO associado ao LED, com as duas densidades de energia utilizadas. Entretanto, nenhuma diferença significativa foi encontrada para os diferentes tempos de irradiação. Concluiu-se que os parâmetros utilizados no presente estudo, para o emprego do LED associado ao TBO, foram efetivos em reduzir a contagem de S. mutans presentes em lesões de cárie dentinária.
Abstract: Photodynamic therapy (PDT) is a technique that consists in the activation of certain photosensitizers by light in the presence of tissue oxygen, resulting in the production of reactive radicals capable of inducing cell death. In this context, this therapy may become a suitable approach to disinfect the dentin tissue during the caries treatment, and reduce the tissue removal, minimizing the probability of caries progression and pulp involvement. This randomized in vitro study determined parameters for using a light-emitting diode (LED) with toluidine blue O (TBO) for reduction of Streptococcus mutans counts inside dentin caries. Seventy two bovine coronary dentin slabs were immersed in Streptococcus mutans culture for demineralization production. Dentin slabs were allocated to 6 groups (n=12) as follows: Control (treated with 0.9% NaCl solution for 5 min); TBO (treated with 0.1 mg/ml TBO for 5 min); LEDA (submitted to irradiation for 4.2 min); LEDB (submitted to irradiation for 6.5 min); PDTA (treated with TBO plus irradiation for 4.2 min) and PDTB (treated with TBO plus irradiation for 6.5 min). The energy densities used for 4.2 and 6.5 min correspond at 166 and 249 J/cm2, respectively. Before and after treatments, dentin samples were analyzed with regard to S. mutans counts. The caries lesion depth produced by the microbiological model was analyzed by polarized light microscopy. ANOVA/Tukey tests were utilized to compare log reductions among groups (a=5%). Bacterial reduction was observed when dentin was exposed to both TBO and LED at both irradiation times. However, no difference in S. mutans reduction was found between the two energy densities. Concluding, although the use of LED combined with TBO was effective in reducing the Streptococcus mutans counts in carious dentin, this effect may not have clinical significance.
Mestrado
Odontopediatria
Mestre em Odontologia
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Vizoto, Natália Leal 1982. "Avaliação da função biológica do sistema de dois componentes SptRS de Streptococcus mutans." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/288675.
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Orientador: Renata de Oliveira Mattos-GranerTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: Streptococcus mutans é uma espécie bacteriana comum da microbiota bucal de seres humanos envolvida na patogênese da cárie dentária e em endocardites infecciosas promovidas por bacteremias de origem bucal. Para ser transmitido e ocupar seus nichos ecológicos, S. mutans precisa persistir na saliva e se adaptar fisiologicamente a cada fase da colonização, um processo que provavelmente envolve diversas alterações do seu transcriptoma. Para isto, S. mutans utiliza sistemas reguladores de transcrição de dois componentes (SDC). O SDC SptRS foi identificado através de análises in silico do genoma da cepa S. mutans UA159, como ortólogo do sistema SptSR (Spt de Saliva persistence) de Streptococcus pyogenes. O objetivo deste trabalho foi investigar a participação do sistema SptRS de S. mutans em fenótipos importantes para a colonização bucal. Para isto, mutantes knockout dos genes sptR e sptS, SMU.927 e SMU.928 respectivamente, foram construídos a partir da cepa UA159 (UAsptR- e UAsptS-) e comparados com a cepa parental em análises de morfologia, crescimento planctônico sob diferentes condições nutricionais, persistência em saliva humana, formação de biofilme e autólise a 44oC. Além disto, genes do regulon de SptRS foram pesquisados através de ensaios da Imunoprecipitacão de Cromatina seguido de sequenciamento (ChIP-seq), RT-PCR quantitativo (RT-PCRq) e de Ensaios de Retardamento da Mobilidade Eletroforética (EMSA) com proteína recombinante SptRr de S. mutans. Os mutantes sptR e sptS mostraram crescimento planctônico lento em meios de cultura RPMI e em MQD comparados à cepa parental, além de atividade autolítica reduzida em 22,4 e 53,13%, respectivamente. Não foram observadas, entretanto, alterações significativas na morfogênese, formação de biofilmes in vitro, nem na persistência em saliva humana. Os dados de ChIP-seq e RT-qPCR indicaram que SptRS regula genes envolvidos na resposta de estringência (SMU.926), repressão catabólica (ccpA), metabolismo de múltiplos açúcares (SMU.78, SMU.137, SMU.542, SMU.1734), sistemas fosfoenolpiruvato-fosfotransferase (PTS) (SMU.2047, SMU.114, SMU.115) sistemas de transporte do tipo ABC (SMU.182, SMU.880, SMU.905, SMU.1035, SMU.1095, SMU.1178c, SMU.1939) e biogênese de parede celular (SMU.1091, SMU.2147, SMU.609, SMU.1434c, SMU.22). SptR funcionou como um regulador negativo em 86% (37/43) dos genes testados. Análises de RT-qPCR e EMSA indicaram ainda que SptR regula diretamente o regulador de transcrição CovR (SMU.1924), envolvido na repressão de genes de virulência e formação de biofilmes. Este estudo fornece evidências de que SptRS regula diversas funções de S. mutans importantes para a sobrevivência em condições nutricionalmente escassos, aparentemente coordenando o metabolismo com o crescimento bacteriano e com a expressão de genes de virulência
Abstract: Streptococcus mutans is a common bacterial species of the bucal microbiota of humans involved in the pathogenesis of dental caries and infectious endocarditis promoted by bacteremia of bucal origin. To be transmitted and occupy their ecological niches, S. mutans need to persist in saliva and adapt physiologically to each phase of colonization, a process that probably involves several changes in its transcriptome. To this end, S. mutans uses transcriptional regulatory systems called Two Component System (TCS). The TCS SptRS was identified in an in silico analysis of the genome of S. mutans strain UA159, as an orthologue of the SptRS system (Spt of Saliva persistence) of Streptococcus pyogenes. The aim of this study was to investigate the role of the TCS SptRS in functional traits important for S. mutans to colonize its bucal niches. Thus, knockout mutants of sptR and sptS (SMU.927 and SMU.928, respectively) were obtained in strain UA159 (UAsptR-, UAsptS-) and compared to parental strain regarding morphology, planktonic growth under different nutritional conditions and persistence in human saliva, biofilm formation and autolysis at 44oC. In addition, genes of SptRS regulon were analised by Chromatin Immunoprecipitation followed the sequencing (ChIP-seq), quantitative RT-PCR (RT- qPCR) and Electrophoretic Mobility Shift Assays (EMSA) with S. mutans SptR recombinant protein. Inactivation of sptR/S promotes slow planktonic growth in RPMI and CDM, culture media 22.4 to 53.13% reductions in autolysis respectively, but does not significantly affect morphogenesis. However, mutants do not show significant alterations in biofilm formation or in persistence in human saliva. ChIP-seq and RT-qPCR analyses showed that SptRS regulates genes for stringent response (SMU.926), metabolism of multiple sugars (SMU.78, SMU.137, SMU.542, SMU.1734), catabolite repression (SMU.1591, ccpA), phosphoenolpyruvate phosphotransferase systems (PTS), ABC transport systems (SMU.182, SMU.880, SMU.905, SMU.1035, SMU.1095, SMU.1178c, SMU.1939) and cell wall biogenesis (SMU.22, SMU.609, SMU.1091, SMU.1434c, SMU.2147) SptR worked as a negative regulator of 86% (37/43) of the tested genes. RT-qPCR and EMSA analyses further showed that SptR directly represses expression of the transcriptional regulator CovR (SMU.1924), which is a repressor of genes involved in biofilm formation and virulence. This study provides evidence that SptRS regulates several functions important for S. mutans survival under poor nutritional conditions, apparently coordinating metabolism with bacterial growth and expression of virulence genes
Doutorado
Microbiologia e Imunologia
Doutora em Biologia Buco-Dental
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Aravena, Solís Franco. "Persistencia en rentabilidad de fondos mutuos : evidencia para el mercado chileno de fondos mutuos accionarios." Tesis, Universidad de Chile, 2017. http://repositorio.uchile.cl/handle/2250/145640.
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TESIS PARA OPTAR AL GRADO DE MAGÍSTER EN FINANZASHoy en día en Chile existen una serie de instrumentos de inversión disponibles para una amplia diversidad de inversionistas, dentro de los que se encuentran depósitos a plazo, acciones y fondos mutuos, entes otros, siendo este último uno de los más populares debido a que cualquier persona que tiene ahorros, puede dirigirse a una administradora general de fondos (de aquí en adelante AGF), e invertir sin necesariamente tener conocimiento o expertise en este mercado. Dado esta popularidad surge la necesidad de entender si efectivamente este instrumento es una buena alternativa para alguien no especialista en inversiones, y con ello ahondar en si este resultado es el mismo indistinto de la AGF. Los fondos mutuos han tenido un alto crecimiento y desarrollo las últimas décadas. En las Figuras 1 y 2 a continuación, se puede ver que si bien el número de sociedades administradoras, sólo aumentó de 13 a 18, desde 2000 a junio de 2016, la cantidad de fondos administrados, aumentó casi cinco veces en este mismo período pasando de ser 124 a 501 fondos. Asimismo, en la Figura 2, se puede ver que el patrimonio administrado, y el número de partícipes, han crecido de forma abrupta desde el año 2000, presentando dos años (2010 y 2014) con crecimiento en el patrimonio anual que destacan por sobre la tendencia al alza sostenida que muestra este mercado. De esta forma, el mercado ha llegado a tener más de dos millones de partícipes, así como también, un patrimonio, de más de 28 billones de pesos, que es cercano a un 18,5%1 del PIB nacional a diciembre de 2016. Cabe destacar que, dentro de los partícipes, se consideran tanto las personas naturales, como las jurídicas.
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Gangloff, Sophie. "Les adhesines des bacteries du groupe mutans : cartographie antigenique d'une proteine de surface de streptococcus mutans." Strasbourg 1, 1991. http://www.theses.fr/1991STR15070.
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Neilands, Jessica. "Acid tolerance of Streptococcus mutans biofilms /." [Malmö, Sweden] : Malmö University, Faculty of Odontology, Department of Oral Biology, 2007. http://www.mah.se/muep.
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Carlsson, Peter. "On the epidemiology of mutans streptococci." Malmö : Dept. of Cariology, Faculty of Odontology, University of Lund, 1988. http://catalog.hathitrust.org/api/volumes/oclc/17942744.html.
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Siri, Aurélien. "Le mutuus dissensus : notion, domaine, régime." Thesis, Aix-Marseille 3, 2011. http://www.theses.fr/2011AIX32054.
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Le mutuus dissensus est une locution latine de droit positif français. Elle est utilisée par la doctrine civiliste depuis la fin du XIXème siècle pour désigner une notion fondamentale du droit des conventions. La notion juridique de mutuus dissensus peut être définie comme la convention par laquelle toutes les parties consentent à la révocation de la convention qu’elles ont conclue antérieurement. La notion de mutuus dissensus présente une unité. Elle repose sur la réunion de deux éléments constitutifs essentiels. Le premier est une procédure classique : une convention. La convention de mutuus dissensus est une véritable convention extinctive plutôt qu’un nouveau contrat identique en sens inverse du contrat révoqué. Le second est un effet de droit spécifique : la révocation. La révocation par mutuus dissensus est plutôt une résiliation du contrat opérant uniquement pour l’avenir qu’une prétendue résolution d’un contrat à effet rétroactif. La notion de mutuus dissensus a un domaine très large en droit positif. La révocation par mutuus dissensus est un principe général du droit des conventions fondé sur l’article 1134, alinéa 2, du Code civil, qui a vocation à s’appliquer à toutes les conventions et dans toutes les matières. La notion de mutuus dissensus détermine un régime juridique spécifique. Les parties sont libres de déterminer les effets de la révocation par mutuus dissensus. Le principe de la liberté des parties est limité par l’ordre public. La sécurité des tiers est assurée par une protection générale et des protections spéciales reposant principalement sur le mécanisme de l’inopposabilitéMutuus dissensus is a latin expression in the French positive law. It has been used by civil doctrine since the end of the nineteenth century to designate a basic notion of Contract Law. The juridic notion of mutuus dissensus may be defined as an agreement between all the parties to rescind their precedent contract. The notion of mutuus dissensus has an unity. It stands on two essentials constituent elements. The first one is a classical procedure: an agreement. Mutuus dissensus agreement is a real subsequent agreement to end a contract, rather than a new identical contract but opposite to the rescinded contract. The second one is an effect of specific right: the rescission. Rescission by mutuus dissensus is the termination of a contract for the future rather than a supposed discharge of a contract with a retroactive effect. The notion of mutuus dissensus has a very wide field in positive law. Rescission by mutuus dissensus is a general principle of law of contracts based on section 1134, subsection 2, of the French civil code, which is to apply to every contract and in every subject. The notion of mutuus dissensus determines a specific juridical system. Parties are free to decide the effects of the rescission by mutuus dissensus. The principle of freedom of parties is limited by law and order. The protection of third parties is ensured by a general protection and special protections which limit the effects of the rescission of contract by mutuus dissensus
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Navarrete, Villavicencio Sandra Iris, and Beltr?n Roc?o Fabiola Tejada. "Sistema de gestión de fondos mutuos." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2013. http://hdl.handle.net/10757/274087.
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El presente trabajo está orientado al desarrollo de un sistema automatizado para fondos mutuos de inversión en valores, que debe cubrir las funciones operativas del fondo y las exigidas por la Comisión Nacional Supervisora de Empresas y Valores (CONASEV), y brindar a las personas encargadas de las inversiones del fondo y a la gerencia general información útil para la consecución de sus funciones. Un fondo mutuo es el patrimonio integrado por aportes voluntarios de personas naturales y jurídicas, llamadas partícipes, para su inversión principalmente en valores de oferta pública y en otros activos autorizados expresamente por CONASEV. Una sociedad administradora de fondos mutuos es una sociedad anónima que tiene como objetivo exclusivo la administración de uno o más fondos mutuos. Las sociedades administradoras requieren de la autorización de CONASEV para su organización y funcionamiento, y es este quien a su vez se encarga de su control y supervisión. En el Perú existen actualmente nueve sociedades administradoras de fondos mutuos de inversión en valores y veintiún fondos mutuos. Haciendo una encuesta en las principales sociedades administradoras de fondos mutuos, se puede afirmar que cada una de ellas utiliza un sistema computarizado propio para el manejo de su fondo el cual brinda información a nivel operativo de la empresa. En la actualidad no existe en el mercado un sistema estándar para la valorización de inversiones y gestión de partícipes de los fondos mutuos y a la vez que sea flexible a los 3 cambios de acuerdo con el reglamento vigente. Esto se puede conseguir si se logra un trabajo en conjunto con CONASEV. En este proyecto se propone construir un sistema de gestión que fortalezca el control de la valorización de las inversiones y sobre los partícipes de un fondo mutuo. Este sistema será un instrumento de apoyo en las tareas del área de inversiones y el área de ventas, brindará información sobre el comportamiento de las inversiones por sectores económicos, categorías de riesgo, tipos de valores, etc., controlará los límites de inversión del fondo y limites de participación de los clientes, dará información sobre la captación de partícipes, incremento de patrimonio del fondo y comisiones para los vendedores. La herramienta de software que se utilizará para el desarrollo del sistema propuesto es el lenguaje Visual Foxpro con un gestor de base de datos relacional SQL Server. Este sistema propuesto será de utilidad para la sociedad administradora y sus fondos mutuos, pues los beneficios que se obtendrán de su utilización se basarán en el acceso interactivo e inmediato a la información de tipo operacional y de tipo estratégica, lo que le permitirá al usuario final tomar decisiones de una forma más rápida y sin perder de vista los objetivos de la empresa. Estos beneficios aumentarán cuanto más importantes sean las decisiones a tomar y cuanto más crítico sea el factor tiempo.Tesis
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Quintana, Meza Aldo. "Los fondos mutuos indexados de renta variable como producto alternativo en la industria peruana de fondos mutuos." Pontificia Universidad Católica del Perú, 2015. http://repositorio.pucp.edu.pe/index/handle/123456789/114739.
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This article analyzes and compares an overview of the structure and evolution of the international and domestic mutual fund industry for the 2005–2014 period. The aim of this analysis is to identify opportunities for growth and development of the domestic mutual fund industry, in particular, passive management used by index equity funds.Este artículo analiza y compara, de manera general, la estructura y evolución anual de la industria de fondos mutuos internacional y doméstica durante el período 2005-2014. El objetivo de este análisis es identificar las oportunidades de crecimiento y desarrollo del segmento de renta variable de la industria de fondos mutuos doméstica tomando como referencia el estilo de administración pasiva de las inversiones utilizado por los fondos mutuos indexados de renta variable.
Este artigo analisa e compara, em geral, a estrutura e a evolução da indústria internacional e nacional de fundos mútuos anuais ao longo do período 2005-2014. O objetivo desta análise é identificar oportunidades de crescimento e desenvolvimento dos fundos mútuos de ações na indústria nacional em função dos fundos de índice com gestão passiva de investimentos.
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Bhatasara, Sandra. "Understanding climate variability and livelihoods adaptation in rural Zimbabwe : case of Charewa, Mutoko." Thesis, Rhodes University, 2015. http://hdl.handle.net/10962/d1018928.
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Rural farmers in Zimbabwe have been grappling with various changes and challenges occurring in the country since the early 1990s. Amongst these, climate variability has emerged as one significant aspect. It has introduced new challenges for these farmers who are already facing various difficulties in maintaining their insecure livelihoods. Yet, current adaptation theories and inquiries have failed to sufficiently account for and analyse the capacity of these farmers to adequately respond to changing climatic conditions. In this respect, a number of studies have been heavily embedded in deterministic concepts that regard rural farmers as passive victims who play only a minor part in decisions and actions that affect their own livelihoods and well-being. Similarly, although some studies have acknowledged farmers’ capacity to adapt and build elements of resilience, they have not adequately shown how farmers interpret changes in climate and the structures, processes and conditions underpinning adaptation. Following that, my study uses a case study of a rural community in a semi-arid region of Mutoko district in eastern Zimbabwe and Margaret Archer’s sociological theory to understand and analyse how farmers problematise climate variability and respond to it. The study utilises a qualitative approach to divulge the subtleties on how rural people interpret processes of change and adapt to such changes. The thesis found that farmers are encountering increasingly unpredictable and unreliable rainfall patterns as well as shifting temperature conditions which are inducing labyrinthian livelihoods conundrums. However, these climatic shifts are not being experienced in a discrete manner hence farmers are also discontented with the obtaining socio-economic circumstances in the country. Simultaneously, whilst farmers in large part conceived changes in rainfall and temperature to be caused by natural shifts in climate, they also ascribed them to cultural and religious facets. Importantly, the thesis reveals considerable resourcefulness by farmers in the face of nascent changes in climate variability. Farmers have therefore constructed versatile coping and adaptive strategies. What is crucial to mention here is that climatic and non-climatic challenges are negotiated concurrently. Therein, farmers are adapting to climate variability and at the same time navigating difficult socio-economic landscapes. All the same, the process of adaptation is ostensibly not straightforward but complex. As it evolves, farmers find themselves facing numerous constraining structures and processes. Nonetheless, farmers in this study are able to circumvent the constraints presented to them and at the same time activate the corresponding enabling structures, processes and conditions.
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Galvão, Lívia Câmara de Carvalho 1985. "Avaliação da atividade antimicrobiana de óleos essenciais contra microrganismos do grupo mutans e determinação da atividade antiproliferativa." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/288527.
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Orientadores: Pedro Luiz Rosalen, Marta Cristina Teixeira DuarteDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: O objetivo desse trabalho foi avaliar a atividade antimicrobiana, in vitro, de óleos essenciais e frações dos óleos de melhor atividade, contra microrganismos do grupo mutans em estado planctônico. Além disso, os biofilmes de Streptococcus mutans foram submetidos às frações ativas e os óleos de melhor atividade e frações ativas foram avaliados quanto à sua citotoxicidade e caracterizados quimicamente. Para isso, vinte óleos essenciais (OE) foram obtidos por hidrodestilação a partir de plantas pertencentes ao banco de germoplasmas da Coleção de Plantas Medicinais e Aromáticas (CPMA/CPQBA/UNICAMP). Estes OE foram avaliados quanto à sua atividade antimicrobiana por meio dos ensaios: concentrações inibitória (CIM) e bactericida mínima (CBM) contra Streptococcus mutans UA159. Controles positivo (clorexidina 0,12 %) e negativo (propilenoglicol 6,12 % e 25 %) também foram testados...Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital
Abstract: The aim of this study was to evaluate the in vitro antimicrobial activity of essential oils (EO) and fractions from highest activity EO against planktonic cells of mutans streptococci. Besides, the biofilms formed by this microorganism were submitted to active fractions and the higher activity EO and active fractions were evaluated regarding their citotoxicity and chemically characterized. For this, twenty essentinal oils were obtained from plants of the "Collectio of Medicinal and Aromatic Plants" (CPMA, CPQBA/UNICAMP), germplasm bank by hydrodistillation. These EO were evaluated by antimicrobial assays: minimum inhibitory (MIC) and bactericidal (MBC) concentrations against Streptococcus mutans UA159. Positive (chlorhexidine 0.12%) and negative (propylene glycol 6.12 % and 25%) controls were also tested...Note: The complete abstract is available with the full electronic document
Mestrado
Farmacologia, Anestesiologia e Terapeutica
Mestre em Odontologia
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Carneiro, Haline de Lima. "Avaliação de propriedades de superfície da liga Ti-35Nb-7Zr-5Ta submetida à anodização e seus efeitos n adesão bacteriana /." Araraquara, 2014. http://hdl.handle.net/11449/110821.
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Orientador: Luís Geraldo VazCo-orientador: Laiza Maria Grassi Fais
Banca: Valfrido Antonio Pereira Filho
Banca: Valentim Adelino Ricardo Barão
Resumo: Este estudo comparou as propriedades de superfície e a adesão Streptococcus mutans na liga Ti-35Nb-7Zr-5Ta e no titânio comercialmente puro (Ti cp) antes e após a anodização. Foram utilizados discos (Ø8mmx2mm; N = 40) divididos em 2 grupos: T (Ti cp), TNZT (Ti-35Nb- 7Zr-5Ta), e subdivididos conforme a realização (A+) ou não (A-, controle) da anodização eletroquímica (300 V, 1 min) em β-glicerofostato de sódio + acetato de cálcio. As propriedades avaliadas foram: topografia de superfície e identificação qualitativa dos elementos químicos (microscópio eletrônico de varredura-MEV/EDS), energia livre de superfície (ELS, mensurada em goniômetro) e rugosidade média (Ra, determinada em rugosímetro). Para avaliação da adesão bacteriana, os discos foram contaminados com Streptococcus mutans (NTCC 25175) para determinação de UFC/mL e do padrão de adesão (MEV). Os valores de Ra e ELS de cada grupo foram comparados (A- vs. A+) por meio do teste Kruskal-Wallis associado ao teste de Dun (α = 0,05). Os valores de Ra (μm) e ELS (mN/m), respectivamente, foram: A-- T=0,97/44,24; TNZT=0,17/36,68; A+ - T=1,21/56,88; TNZT=0,53/53,64, com aumento significante de ambas propriedades (p < 0,05) após a anodização. A análise em MEV/EDS indicou a formação de uma camada multiporosa, com deposição de íons Ca e P nos subgrupos A+. Após a anodização houve aumento na adesão do patógeno apenas na liga TNZT. Conclui-se que a anodização do Ti cp e da liga TNZT alteram as propriedades de superfície com potencial para melhorias na osseointegração, contudo há aumento na adesão de S. mutans na liga TNZT.
Abstract: The aim of this study was to compare the surface properties and the adhesion of Streptococcus mutans on Ti-35Nb-7Zr-5Ta and commercially pure titanium (cp Ti) before and after the anodization. Discs (Ø8mmx2mm, N=40) were divided into 2 groups: T (cp Ti), TNZT (Ti-35Nb-7Zr- 5Ta), and subdivided in untreated (A- , control) or anodic treated (A+) in β- glicerofostato + calcium acetate (300 V, 1min). The evaluated surface properties were: surface topography and qualitative identification of chemical elements (in scanning electron microscope -SEM/EDS), surface free energy (SFE, measured with a goniometer), and the average roughness (Radetermined in profimoleter). The discs were contaminated with Streptococcus mutans (NTCC 25175) for determination of CFU/mL; the surfaces with adhered viable cell were also analyzed with SEM. The values of Ra and ELS were compared (A- vs . A+) by means of Kruskal-Wallis associated Dun test (α= 0.05). The median Ra (μm) and ELS (mN/m), respectively, were: A- T=0.97/44.24; TNZT=0.17/36.68; A+ T=1.21/56.88; TNZT=0.53/ 53.64. All groups showed significantly higher values of Ra and ELS (p < 0.05) after anodizing. The analysis in SEM/EDS indicated the formation of a multiporous layer with deposition of Ca and P ions. Only anodic treated TNZT exhibited an increase in adhesion of S. mutans. It was concluded that the anodic tretament of Ti cp and TNZT change the surface properties with potential improvements for osseointegration, despite the increase in the adhesion of S. mutans on TNZT.
Mestre
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Brown, James. "DNA mismatches : their structure and recognition by MutS." Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313214.
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Wallman, Catarina. "On mutans streptococci in margins of restorations." Göteborg, [Sweden] : Dept. of Cariology, Faculty of Odontology, Göteborg University, 1994. http://catalog.hathitrust.org/api/volumes/oclc/32080686.html.
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Koning, J. W. "Interactions between Streptococcus mutans and Veillonella dispar." Thesis, University College London (University of London), 2012. http://discovery.ucl.ac.uk/1344047/.
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Dental plaque, a collection of bacteria forming a biofilm, is the cause of the most common diseases of mankind: caries and periodontal diseases. This study reports on the interactions occurring between two key species in this biofilm Streptococcus mutans and Veillonella dispar. These organisms are hypothesised to form a cooperative metabolic system in which a waste product, lactic acid, produced by S. mutans is utilised by V. dispar. The objective of this thesis was to evaluate whether these species cooperate to determine whether knowledge of their interaction can be applied to prevent caries. The hypothesis was examined in single and dual species planktonic cultures and biofilms which were continued for up to 14 days, with their growth, vitality, microstructure and environment closely monitored. S. mutans gene expression was quantified during two stages of biofilm growth to determine the effects of V. dispar co-culture. A qualitative model was developed that coupled the growth and decline of S. mutans and V. dispar around lactic acid. Experiments were conducted in silico to determine whether the interaction could be modulated to improve health, and the model was expanded to include a third species to investigate the production of lactic acid as a competitive strategy. The results demonstrated the two species had a mutually beneficial relationship initially, but lactic acid rapidly accumulated and killed V. dispar. S. mutans gene expression changed considerably in co-culture, including upregulation of bacteriocins. The initial hypothesis that the species cooperate because V. dispar removes lactic acid was rejected as S. mutans produces lactic acid as a chemical warfare agent and does not want it removed. The principal conclusion is that S. mutans employs a strategy of acidogenicity and aciduricity to gain dominance in the dental plaque biofilm. This strategy overwhelms the benefit from cooperative interactions that remove lactic acid and thus sociobiological approaches to prevent caries should focus on competitive interventions.
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Lowes, Sarah. "Proteases and surface proteins of Streptococcus mutans." Thesis, University of Newcastle Upon Tyne, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.424293.
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(UPC), Universidad Peruana de Ciencias Aplicadas. "Gestión de banca personal. MTA5. Fondos mutuos." Universidad Peruana de Ciencias Aplicadas (UPC), 2013. http://hdl.handle.net/10757/306021.
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Describir la gestión de los fondo mutuos como producto adicional dentro de la oferta valor de captaciones del gerente del producto de la institución financiera. Resaltando el mercado de valores, los riesgos, los fondos mutuos de inversión en valores y los canales de distribución.
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Granzow, Cortés Herman, and Moreno Karla Romo. "Estilo de inversión en fondos mutuos chilenos." Tesis, Universidad de Chile, 2006. http://www.repositorio.uchile.cl/handle/2250/108408.
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Seminario para optar al Título de Ingeniero ComercialLos Fondos Mutuos o también conocidos como Fondos Comunes en algunos países de habla hispana, tal como su nombre lo índica son fondos comunes de inversión formados por los depósitos de múltiples inversionistas, quienes optan por este tipo de inversión pues ella les permite participar en inversiones que requieren de un mayor capital, que por sí solos no podrían reunir, y junto con ello pueden diversificar un cierto nivel de riesgo que individualmente les sería imposible asumir y así obtener un mayor nivel de retorno que estos dos factores en conjunto justifican.
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Poblete, Moreno Claudio, and F. Fabián Linares. "Análisis de la industria de Fondos Mutuos." Tesis, Universidad de Chile, 2006. http://repositorio.uchile.cl/handle/2250/142000.
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SEMINARIO DE TITULO INGENIERO COMERCIAL, MENCIÓN ECONOMÍAEl objetivo de nuestro trabajo es analizar el funcionamiento del mercado de Fondos Mutuos en Chile. Para esto se estudia la evolución que ha tenido la industria desde sus inicios hasta el año 2006 en términos de patrimonio administrado, partícipes en el sistema, uso de derivados, estructura de comisiones y aspectos tributarios. Además se muestra como han evolucionado estas variables para cada uno de los 8 tipos de Fondos Mutuos existentes hasta la fecha. Luego del análisis de la industria de Fondos Mutuos se muestran los principales indicadores para medir el desempeño de éstos, así como los resultados de su aplicación en diferentes investigaciones posteriores a 1990 tanto nacionales como internacionales. Se concluye que la industria de Fondos Mutuos ha tenido una constante evolución desde sus inicios, pero no sin dificultades. Las crisis de los años 80, así como la crisis de 1997 hicieron perder dinamismo al sector implicando el retiro de muchos partícipes y la disminución del patrimonio administrado. En cuanto al uso de instrumentos derivados la cantidad invertida ha sido variable con mayores alzas en contratos de “Futuros” y “Forward” de Compra y mayores bajas en “Opciones de venta” en el periodo 2000-2005. Con respecto a los principales estudios que se analizan en este trabajo se encuentra que los Fondos Mutuos en promedio no han generado rendimientos superiores para los inversionistas. Nuestro trabajo sirve para interiorizarse en el funcionamiento de la industria y como una primera parte del análisis más específico que realizarán los autores sobre los flujos hacia los Fondos Mutuos, así como el desempeño de las inversiones en derivados y el desempeño de las “Familias” de Fondos Mutuos, trabajos que serán presentados como Tesis para optar al grado de Magíster en Finanzas.
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Fournier, Maurice. "Philosophie et sexualité : entre Muthos et Logos." Thèse, Université du Québec à Trois-Rivières, 1985. http://depot-e.uqtr.ca/6036/1/000556586.pdf.
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Pérez, Rossi M. Alejandra. "Bolsa Off Shore. Bolsa de Fondos Mutuos." Tesis, Universidad de Chile, 2000. http://www.repositorio.uchile.cl/handle/2250/107212.
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Memoria (licenciado en ciencias jurídicas y sociales)No autorizada por el autor para ser publicada a texto completo
En términos generales, el objetivo principal de la bolsa off-shore chilena es permitir la oferta pública de valores de emisores extranjeros (acciones, cuotas de fondos mutuos, cuotas de fondos de inversión, etc.) mediante su colocación directa en el mercado chileno o mediante la emisión de certificados representativos de acciones extranjeras denominados CDV’s. A fin de poder operar en la bolsa off-shore, estos instrumentos deben ser inscritos en un registro público especial denominado Registro de Valores Extranjeros, llevado por la Superintendencia de Valores y Seguros.
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Branting, Christina. "Studies on S̲t̲r̲e̲p̲t̲o̲c̲o̲c̲c̲u̲s̲ m̲u̲t̲a̲n̲s̲ glucans with special reference to cell adhesion." Stockholm : Kongl. Carolinska Medico Chirurgiska Institutet, 1988. http://catalog.hathitrust.org/api/volumes/oclc/18171129.html.
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Lindquist, Birgitta. "Mutans streptococci in human dentition some factors influencing colonization and distribution /." Göteborg : University of Göteborg, 1991. http://catalog.hathitrust.org/api/volumes/oclc/25383720.html.
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Almeida, Luciana Salles Branco de. "Atividade antimicrobiana dos extratos da Rheedia brasiliensis e potencial anticarie do seu composto bioativo." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/288507.
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Orientador: Pedro Luiz RosalenDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
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Resumo: Este estudo avaliou a atividade antimicrobiana de extratos da Rheedia brasiliensis contra Streptococcus mutans e o potencial anticárie do seu composto ativo isolado. Os extratos hexânicos (EH), acetato de etila e etanólico (concentrações entre 6,25-800 µg/ml) do fruto (¿bacupari¿) foram testados contra S. mutans UA159 por meio de determinação das concentrações inibitória mínima (CIM) e bactericida mínima (CBM). Biofilmes de 5 dias de formação foram tratados com os extratos ativos (100 x CIM), por 0, 1, 2, 3 e 4 h, e plaqueados para contagem das UFC/ml (time kill). Os extratos ativos foram submetidos à análise química por métodos espectroscópicos, e o composto ativo isolado (0,625-80 µg/ml) foi testado contra células de S. mutans por meio de CIM/CBM. A influência do composto isolado (12,5-100 µg/ml) sobre a síntese de glucanos foi avaliada através da atividade da enzima glucosiltranferase (GTF) B em superfície de hidroxiapatita. A ação do composto sobre biofilmes (125 e 250 µg/ml) foi testada com os ensaios de queda de pH e inibição de formação de biofilme. O potencial anticárie do composto (250 µg/ml) foi avaliado em ratas Wistar sob alto desafio cariogênico. Os EH (casca e semente) inibiram S. mutans em baixas concentrações (CIM:12,5-25 µg/ml) e reduziram células viáveis dos biofilmes após 4 h de exposição. O composto ativo presente foi identificado como a 7- epiclusianona (7-epi), a qual inibiu o crescimento do S. mutans (CIM:1,25-2,5 µg/ml), a atividade da GTF B em superfície (48% de inibição) e a produção de ácidos do S. mutans em biofilme, porém não reduziu a formação e o acúmulo dos biofilmes. No estudo animal, a 7-epi reduziu a incidência e a severidade de cárie e a microbiota total, mas não diminuiu a porcentagem de S. mutans. A 7-epi diminuiu a virulência do S. mutans e inibiu o desenvolvimento de cárie in vivo, sugerindo ser um agente terapêutico promissor para o controle do biofilme dental cariogênico. Palavras-chave: Rheedia brasiliensis, 7-epiclusianona, Streptococccus mutans, fatores de virulência, cárie animal
Abstract: The present study evaluated the antimicrobial activity of Rheedia brasiliensis extracts against Streptococcus mutans and the anticaries properties of its isolated bioactive compound. Hexane (HE), ethyl-acetate and ethanolic extracts (concentrations ranging from 6.25 to 800 µg/ml) of R. brasiliensis fruits (¿bacupari¿) were tested against S. mutans UA159 by determining the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). S. mutans 5-days-old biofilms were treated with active extracts (100 x MIC), for 0, 1, 2, 3 e 4 h (time-kill), and plated for colony counting (UFC/ml). Such extracts were submitted to exploratory chemical analyses to isolate and identify the bioactive compound using spectroscopic methods. The compound (0.625-80 µg/ml) was then tested against S. mutans cells using MIC/MBC assays. The influence of the bioactive compound (12.5-100 µg/ml) on glucans synthesis was evaluated by testing the activity of glucosyltranferase (GTF) B on hydroxyapatite surface. The effects of the compound (125 e 250 µg/ml) on biofilms were analyzed using glycolytic pH-drop and inhibition of formation assays. The anticaries activity of such compound (250 µg/ml) was evaluated in Wistar rats submitted to a high cariogenic challenge. HE (peel and seeds) reduced S. mutans cells at low concentrations (MIC:12.5-25 µg/ml) and also biofilm viability after four hours, confirming the presence of the bioactive compound. This compound was identified as 7-epiclusianone (7-epi), which inhibited the S. mutans growth (MIC:1.25-2.5 µg/ml), the activity of GTF B (48% of inhibition) and the acid production, not interfering with the formation and accumulation of biofilms. In the animal study, 7-epi additionally reduced the incidence and severity of caries and also the total microbiota, however no reduction on the percentage of S. mutans was observed. In conclusion, 7-epi may be considered a promising agent to control cariogenic dental biofilm. Keywords: Rheedia brasiliensis, 7-epiclusianone, Streptococccus mutans, virulence factors, animal caries
Mestrado
Farmacologia, Anestesiologia e Terapeutica
Mestre em Odontologia
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Ccahuana, Vasquez Renzo Alberto. "Desenvolvimento e validação de um modelo de crescimento de biofilmes de S. mutans e estudo do efeito da sacarose na expressão de gtfBCD e dexA em biofilmes dentais formados in vitro e in situ." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/289274.
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Orientador: Jaime Aparecido CuryTese (doutorado) - Universidade Estadual de Campinas. Faculdade de Odontologia de Piracicaba
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Resumo: Modelos in vitro e in situ tem sido desenvolvidos para o estudo do biofilme dental. Protocolos que simulem episódios de "fartura-miséria" quando açúcares da dieta estão presentes na cavidade bucal e permitam avaliação de cárie dental são necessários. Por outro lado, poucos estudos da expressão gênica de biofilmes formados in situ foram realizados. Assim, este trabalho teve como objetivos: Desenvolver e validar um modelo de formação de biofilme de S. mutans que simule episódios de "fartura-miséria" e permita avaliar mudanças no biofilme, e desmineralização do esmalte dental. Também, avaliar o efeito da sacarose na expressão de genes gtfB, gtfC, gtfD e dexA de biofilme dental formado in vitro e in situ. Para os primeros objetivos, biofilmes de S. mutans UA159 cresceram durante 5 dias sobre blocos de esmalte bovino a 37oC, 10% CO2, em meio de cultura ultrapurificado, sendo avaliado: o efeito de concentração (1 a 20%) de sacarose e da freqüência (0 a 8x/dia) de exposição à sacarose. O efeito da clorexidina (0, 012 a 0,12%) 2x/dia e de NaF 0,05% foram testados para validar o modelo. Foram determinadas: viabilidade bacteriana, acidogenicidade do biofilme, biomassa e polissacarídeos; e a desmineralização do esmalte. Para o último objetivo, no estudo in vitro biofilmes de S. mutans UA159 cresceram nas mesmas condições acima citadas e foram expostos à sacarose 1% constante (controle) ou sacarose 10% 8x/dia (grupo intermitente) e após 48, 72 e 120 h os biofilmes foram coletados para análise gênica de gtfB, gtfC, gtfD e dexA. No experimento in situ, um estudo cruzado de 2 fases experimentais de 7 dias foi realizado, com 9 voluntários que usaram um dispositivo palatino contendo 12 blocos de dentina que foram submetidos 8x/dia a soluções de sacarose de 1, 5, 10 e 20%. No final, os biofilmes foram coletados para análise microbiológica, bioquímica e de expressão gênica de gtfB, gtfC, gtfD e dexA. Os resultados de padronização mostraram que as concentrações de sacarose de 10% e 20% e a frequência 8x/dia provocam mudanças no biofilme e na demineralização similares ao controle. Clorexidina mostrou efeito dose resposta, diminuindo biomassa, viabilidade bacteriana, acidogenicidade do biofilme e demineralização do esmalte, NaF 0,05% não mostrou atividade antimicrobiana, mas apresentou similar efeito a clorexidina 0,12% na redução da desmineralização. Para o último objetivo, os resultados in vitro do grupo intermitente mostraram que a expressão de genes analisados parece ser constante enquanto que no controle a expressão desses genes incrementou-se em função ao tempo. No estudo in situ, o incremento da concentração de sacarose aumentou os valores de peso úmido do biofilme, lactobacilos e polissacarídeos extracelulares do biofilme. Quanto a expressão gênica, só foi possível quantificar o gtfB e não apresentou diferenças entre os grupos. Em conclusão, o modelo in vitro apresenta potencial para avaliar o efeito antimicrobiano de substâncias sobre biofilmes e desmineralização dental. A quantificação da expressão de genes gtfB, gtfC, gtfD e dexA foi possível in vitro, mas in situ somente a expressão de gtfB foi determinada e não parece ser regulada pela concentração de sacarose.
Abstract: In vitro and in situ models have been developed to study dental biofilms. Protocols, that simulate the alternations of "feast or famine" episodes that happen in oral environment in the presence of dietary carbohydrates and allowing dental caries evaluation, are necessaries. On the other hand, few studies about gene expression of dental biofilm formed in situ were performed. Thus, the objectives of this research were: To develop and to validate a model of S. mutans biofilm formation simulating 'feast-famine' episodes that allows biofilms and dental demineralization changes assessment. Also, to evaluate the effect of sucrose exposure on expression of gtfB, gtfC, gtfD and dexA of in vitro and in situ dental biofilms. For the first objectives, S. mutans UA159 biofilms were grown during 5 days on bovine enamel slabs at 37oC, 10% CO2 in ultra-purified culture media. To develop the model, the effect of sucrose concentration (1 - 20%) 8x/day and frequency (0 - 8x/day) exposure were evaluated and to validate the model, chlorhexidine (CHX) effect (0.012- 0.12%) 2x/day was tested. Bacterial viability, biofilm acidogenicity, biomass and polysaccharides were determined, and enamel demineralization was evaluated by surface hardness loss. To the last objective, for in vitro study, S. mutans UA159 biofilms were grown in the same conditions of previous experiments and were exposed to 1% sucrose constantly (control) or 10% sucrose 8x/day (intermittent group) and after 48, 72 and 120 h the biofilms were collected for analysis. For in situ experiment, a crossover study was conducted in two phases of 7 days each, with nine volunteers that wore intraoral palatal appliances containing 12 dental dentin slabs, which were extra orally submitted 8 times/day to sucrose solutions of 1%, 5%, 10% and 20% . On the 7th day, biofilms were collected for analysis. RNA from the in vitro and in situ biofilms were extracted and purified. Gene expression of gtfB, gtfC, gtfD and dexA were evaluated by real time PCR. In vitro development and validation results showed that 10% and 20% sucrose concentrations and frequency 8x/day provoked biofilm and enamel demineralization changes similar to control group. CHX showed dose-response effect decreasing biomass, bacterial viability and enamel demineralization (p<0.05). Also, 0.05% NaF did not show antimicrobial effect but had similar effect than 0.12% CHX decreasing enamel demineralization (p<0.05). With regard to gene expression of in vitro experiment, gene expression of intermittent group was constant along the time. In situ results showed that biofilm wet weight, lactobacillus, extracellular polysaccharides values of the biofilm increased according to the increase of sucrose exposure. No differences for gtfB gene expression between the groups were observed (p<0.05) and no levels of gtfC, gtfD and dexA were detected. In conclusion, the model developed and validated has potential to assess substances with antimicrobial effect on biofilm and dental demineralization. Quantification of gtfB, gtfC, gtfD and dexA gene expression levels were possible for S. mutans biofilms in vitro study but only gtfB gene expression of in situ study can be determined and was not regulated by sucrose concentration.
Doutorado
Cariologia
Doutor em Odontologia
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Cavichioli, Eder Augusto Mastropietro. "Fototerapia com luz azul combinada à aplicação de clorexidina 0,12% em um modelo ortodôntico com biofilme cariogênico /." Araraquara, 2020. http://hdl.handle.net/11449/192572.
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Orientador: Luiz Gonzaga Gandini JuniorResumo: Aparelhos ortodônticos fixos criam áreas de estagnação para biofilmes dentários e dificultam a limpeza dos dentes; portanto, existe o risco de desenvolver lesões incipientes de cárie durante o tratamento ortodôntico. O objetivo deste estudo é verificar se a aplicação de luz azul antes da clorexidina 0,12% no esmalte, bráquete e elástico ortodôntico reduziria ou inibiria os biofilmes maduros de Streptococcus mutans e seu crescimento nesses substratos 24 horas após a aplicação dos tratamentos; e se esse tratamento interfere na adesão do bráquete ao esmalte. Biofilmes de S. mutans UA159 foram formados por 5 dias sobre amostras compostas por esmalte bovino, bráquete ortodôntico e elástico ortodôntico. Em seguida, as amostras foram tratadas com NaCl 0,89% por 1 minuto (NaCl), luz azul por 12 minutos (BL), clorexidina 0,12% por 1 minuto (CHX) e luz azul por 12 minutos seguido da aplicação de clorexidina 0,12% por 1 minuto (BL+CHX). O acúmulo de biofilme imediatamente após os tratamentos e 24 horas após os tratamentos foram avaliados por unidades formadoras de colônias (CFU) e peso seco (DW). O pH do meio foi medido no quinto dia e sexto dia. A formação de biofilme nas amostras após os tratamentos (Imediato) e no recrescimento (Regrowth) foi avaliada visualmente por microscopia confocal de varredura a laser (CLSM). O teste de adesão (SBS) entre o bráquete e o esmalte foi feito após as amostras serem termocicladas por 500 ciclos (5°C e 55°C), tratadas e termocicladas novamente nas me... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Fixed orthodontic appliances create areas of stagnation for dental biofilms and make it difficult to clean the teeth; therefore, there is a risk of developing incipient lesions of caries during the orthodontic treatment. The objective of this study is to verify if the application of blue light prior to 0.12% chlorhexidine (CHX) on enamel, orthodontic brackets and elastics would reduce or inhibit mature Streptococcus mutans biofilms and their regrowth on these substrates 24 h after the application of the treatment; and if this treatment would interfere with bracket adhesion to the enamel. Biofilms of S. mutans UA159 were formed for 5-days over samples composed by a bovine enamel, an orthodontic bracket and an orthodontic elastic. Then, the samples were treated with 0.89% NaCl for 1 minute (NaCl), blue light for 12 minutes (BL), 0.12% chlorhexidine for 1 minute (CHX) and BL for 12 min + 0.12% CHX for 1 min (BL+CHX). Biofilm accumulation immediately after treatments and 24-h after treatments (regrowth) were evaluated by colonies forming units (CFU) and dry weight (DW). The pH of the spent media was measured on the 5th and 6th day. Biofilm formation on the samples after the treatments and on the regrowth was visually evaluated by confocal laser scanning microscopy (CLSM). Shear bond strength (SBS) between bracket and enamel was evaluated after specimens were thermocycled for 500 cycles (5° and 55 °C), treated and thermocycled again in the same conditions. Shear forces (N/mm2 ) we... (Complete abstract click electronic access below)
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Arias, Laís Salomão. "Efeito do tirosol sobre biofilmes de streptococcus mutans /." Araçatuba, 2016. http://hdl.handle.net/11449/135864.
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Orientador: Douglas Roberto MonteiroCoorientador: Alberto Carlos Botazzo Delbem
Banca: Farli Aparecida Carrilho Boer
Banca: Debora de Barros Barbosa
Resumo: O tirosol é uma molécula de quorum-sensing (QS) que participa do controle da morfogênese em Candida albicans. Contudo, seu efeito como agente antimicrobiano sobre biofilmes de Streptococcus mutans permanece desconhecido. Assim, o objetivo deste estudo foi avaliar o efeito do tirosol em diferentes concentrações sobre a produção de ácido e formação de biofilmes por S. mutans ATCC 25175, bem como quantificar biofilmes pré-formados desta espécie desenvolvidos sobre espécimes de hidroxiapatita (HA) e tratados com tirosol. A concentração inibitória mínima (CIM) de tirosol sobre células no estado planctônico foi determinada de acordo com o método da microdiluição. Na sequência, biofilmes de S. mutans foram formados durante 48 horas sobre espécimes de HA na presença de diferentes concentrações de tirosol (11,25, 22,5, 50, 100 e 200 mmol l-1), usando saliva artificial como meio de cultura. Após, a produção de ácido foi avaliada através da mensuração do pH do meio, enquanto a formação de biofilmes foi determinada através da quantificação da biomassa total (BT), atividade metabólica (AM) e número de unidades formadoras de colônias (UFCs). Ainda, biofilmes pré-formados (24 horas) de S. mutans foram tratados com tirosol a 100 e 200 mmol l-1 por 1 minuto, duas vezes ao dia, durante três dias, totalizando biofilmes de 96 horas. Em seguida, a atividade antimicrobiana foi avaliada por meio da quantificação da BT, AM, número de UFCs e composição da matriz extracelular (proteínas e carboidratos). Gluconato de clorexidina (490 μmol l-1) foi usado como controle positivo. Os dados foram analisados por ANOVA a um critério, seguido pelos testes de Tukey e Holm-Sidak (α = 0,05). Microscopia eletrônica de varredura (MEV) foi utilizada na análise da estrutura dos biofilmes. A CIM de tirosol foi 90 mmol l-1. Tirosol em concentrações...
Abstract: Tyrosol is a quorum-sensing molecule (QS) that participates in the control of Candida albicans morphogenesis. However, its effect as an antimicrobial agent on Streptococcus mutans biofilms remains unknown. Thus, the aim of this study was to evaluate the effect of tyrosol at different concentrations on the acid production and biofilm formation by S. mutans ATCC 25175, as well as to quantify pre-formed biofilms of this species developed on hydroxyapatite (HA) specimens and treated with tyrosol. Minimum inhibitory concentration (MIC) of tyrosol against planktonic cells was determined in accordance with the microdilution method. Subsequently, S. mutans biofilms were formed during 48 hours on HA specimens in the presence of different concentrations of tyrosol (11.25, 22.5, 50, 100 and 200 mmol l-1), using artificial saliva as culture medium. Next, the acid production was assessed by pH determination of the medium, while the biofilm formation was determined through quantification of total biomass (TB), metabolic activity (MA) and number of colony-forming units (CFUs). Further, S. mutans pre-formed biofilms (24 h) were treated with tyrosol at 100 and 200 mmol l-1 twice a day for 1 min, during 3 days, totaling 96-h biofilms. Then, the antimicrobial activity was evaluated through quantification of TB, MA, number of CFUs and composition of biofilms' extracellular matrix (proteins and carbohydrates). Chlorhexidine gluconate (490 μmol l-1) was used as positive control. Data were analyzed by one-way ANOVA, followed by Tukey's and Holm-Sidak's tests (α = 0.05). Scanning electron microscopy (SEM) observations were performed in order to analyze biofilms' structure. MIC of tyrosol was 90 mmol l-1. Tyrosol at sub-inhibitory concentrations (11.25 and 22.5 mmol l-1) was not able to significantly reduce acid production by S. mutans biofilms. However, biofilms...
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Al-Osaighari, Suhair Wadeea Abbood. "Colonisation of model oral biofilms by Streptococcus mutans." Thesis, University of Newcastle upon Tyne, 2017. http://hdl.handle.net/10443/3934.
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Dental plaque is a mixed-species microbial biofilm that forms on tooth surfaces. Incorporation of acidogenic bacteria such as Streptococcus mutans within the biofilm results in development of carious lesions. This research project aims to establish a reproducible model of early colonising oral bacteria and use it to assess S. mutans integration into biofilms. The Modified Robbins Device (MRD) was used to develop mixed species biofilms from Streptococcus gordonii DL1, Actinomyces oris MG1, and Veillonella parvula PK1910, with or without 0.1% sucrose. These biofilms were challenged with S. mutans UA159 or GS5. Quantitative PCR and a variety of microscopic imaging approaches were used to assess the structure and stability of early coloniser biofilms and to study S. mutans incorporation. Reproducible and stable early coloniser biofilms were established. The presence of sucrose had no effect on biofilm formation. Challenging preformed biofilms with S. mutans had no effect on the early coloniser species, but resulted in differences in the appearance of biofilm matrix. Significant differences were observed between S. mutans strains: after 24 h S. mutans UA159 was about 20-fold more abundant in the biofilm than S. mutans GS5. The impact of extracellular DNA on S. mutans GS5 colonisation was studied by replacing the wild-type S. gordonii with a mutant disrupted in the ssnA gene encoding an extracellular deoxyribonuclease. There was no significant difference in S. mutans between preformed biofilms with wild-type and mutant S. gordonii, indicating that SsnA does not play a role in determining S. mutans colonisation in this system. A reproducible system for culturing early coloniser oral biofilms has been established here that will be useful for further investigations of biofilm colonisation by oral bacteria. Differences in the ability of different S. mutans strains to colonise may be further explored through targeted mutagenesis to find key factors responsible for colonisation.
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Guimarães, Murilo de Sousa [UNESP]. "Contaminação cruzada em escovas dentais por Streptococcus mutans." Universidade Estadual Paulista (UNESP), 2005. http://hdl.handle.net/11449/95498.
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O objetivo deste estudo foi avaliar a contaminação de escovas dentais por Streptococcus grupo mutans e a ocorrência de infecção cruzada por Streptococcus mutans após armazenagem conjunta das mesmas. A amostra foi composta de 46 crianças de 6 a 7 anos de idade divididas em Grupo A com 22 e Grupo B com 24 alunos, de acordo com a sala de aula que freqüentavam. As amostras de biofilme obtidas da cavidade bucal das crianças no início do estudo e o biofilme das escovas dentais das crianças que compartilhavam o mesmo ambiente, foram recolhidas após 21 dias e cultivadas sob condições adequadas em meio de cultura SB20. Em cada escova foram isoladas UFC com morfologia típica, as quais foram identificadas por meio de testes bioquímicos e o polimorfismo genético foi detectado pela técnica de AP-PCR. Pode-se observar 94 UFC de Streptococcus mutans isoladas a partir das escovas dentais. O crescimento bacteriano ocorreu em 14 escovas dentais, sendo que 6 escovas pertenciam às crianças do Grupo A, e 8 às crianças do Grupo B. Dos microrganismos encontrados nas escovas dentais, 83,92% eram Streptococcus mutans. Todos os isolados apresentaram perfil genético distinto, com exceção de 4 e 3 amostras dos Grupo A e B respectivamente, os quais pertenciam a mesma escova dental. Pode-se concluir que dos microrganismos encontrados, ocorreu maior prevalência de colonização por Streptococcus mutans nas crianças e escovas analisadas, não havendo evidência de que a armazenagem conjunta de escovas dentais pode ser um veículo para infecção cruzada por este microrganismo.
The aim of this study was to evaluate the contamination of toothbrushes by mutans streptococci and cross-section infection of Streptococcus mutans. Forty-six children aged from 6 and 7 years were divided into two groups, Group A with 22 children and Group B with 24, according to attending class. A dental plaque sample from each participant was collected at the beginning of the study and the plaque present in toothbrushes was collected after 21 days. The samples were processed and cultivated under adequate conditions in SB20 medium. Typical morphotype mutans streptococci colonies were isolated and submitted to bioquimical tests for identification. An arbitrarily primed polymerase chain reaction (AP-PCR) method was performed for genotypic characterization of Streptococcus mutans. Fourteen toothbrushes were contaminated by mutans streptococci, 6 in Group A and 8 in Group B. Streptococcus mutans represented 83,92% of the mutans streptococci identified. The presence of matching genotypes of Streptococcus mutans has occurred in 4 strains of Group A and in 3 strains of Group B. However, for both groups, the matching genotypes belonged to the same toothbrush. In conclusion, Streptococcus mutans was the predominant specie in both dental plaque and toothbrush. The latter did not represent a source of cross-sectional infection of such microorganism.
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Guimarães, Murilo de Sousa. "Contaminação cruzada em escovas dentais por Streptococcus mutans /." Araraquara : [s.n.], 2005. http://hdl.handle.net/11449/95498.
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Resumo: O objetivo deste estudo foi avaliar a contaminação de escovas dentais por Streptococcus grupo mutans e a ocorrência de infecção cruzada por Streptococcus mutans após armazenagem conjunta das mesmas. A amostra foi composta de 46 crianças de 6 a 7 anos de idade divididas em Grupo A com 22 e Grupo B com 24 alunos, de acordo com a sala de aula que freqüentavam. As amostras de biofilme obtidas da cavidade bucal das crianças no início do estudo e o biofilme das escovas dentais das crianças que compartilhavam o mesmo ambiente, foram recolhidas após 21 dias e cultivadas sob condições adequadas em meio de cultura SB20. Em cada escova foram isoladas UFC com morfologia típica, as quais foram identificadas por meio de testes bioquímicos e o polimorfismo genético foi detectado pela técnica de AP-PCR. Pode-se observar 94 UFC de Streptococcus mutans isoladas a partir das escovas dentais. O crescimento bacteriano ocorreu em 14 escovas dentais, sendo que 6 escovas pertenciam às crianças do Grupo A, e 8 às crianças do Grupo B. Dos microrganismos encontrados nas escovas dentais, 83,92% eram Streptococcus mutans. Todos os isolados apresentaram perfil genético distinto, com exceção de 4 e 3 amostras dos Grupo A e B respectivamente, os quais pertenciam a mesma escova dental. Pode-se concluir que dos microrganismos encontrados, ocorreu maior prevalência de colonização por Streptococcus mutans nas crianças e escovas analisadas, não havendo evidência de que a armazenagem conjunta de escovas dentais pode ser um veículo para infecção cruzada por este microrganismo.Abstract: The aim of this study was to evaluate the contamination of toothbrushes by mutans streptococci and cross-section infection of Streptococcus mutans. Forty-six children aged from 6 and 7 years were divided into two groups, Group A with 22 children and Group B with 24, according to attending class. A dental plaque sample from each participant was collected at the beginning of the study and the plaque present in toothbrushes was collected after 21 days. The samples were processed and cultivated under adequate conditions in SB20 medium. Typical morphotype mutans streptococci colonies were isolated and submitted to bioquimical tests for identification. An arbitrarily primed polymerase chain reaction (AP-PCR) method was performed for genotypic characterization of Streptococcus mutans. Fourteen toothbrushes were contaminated by mutans streptococci, 6 in Group A and 8 in Group B. Streptococcus mutans represented 83,92% of the mutans streptococci identified. The presence of matching genotypes of Streptococcus mutans has occurred in 4 strains of Group A and in 3 strains of Group B. However, for both groups, the matching genotypes belonged to the same toothbrush. In conclusion, Streptococcus mutans was the predominant specie in both dental plaque and toothbrush. The latter did not represent a source of cross-sectional infection of such microorganism.
Orientador: Angela Cristina Cilense Zuanon
Coorientador: Denise Madalena Palomari Spolidorio
Banca: Josimeri Hebling
Banca: Marcelo Fabiano Gomes Boriollo
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Rabinovich, Débora. "Baltasar Gracian et Jacques Lacan : des éclairages mutuels." Paris 8, 1996. http://www.theses.fr/1996PA08A003.
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Busuioc, Monica. "Survival Strategies of Streptococcus mutans during Carbohydrate Starvation." Diss., Temple University Libraries, 2010. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/88876.
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Microbiology and ImmunologyPh.D.
Streptococcus mutans is a facultative member of the oral plaque and is associated with dental caries. It is able to survive long periods of sugar starvation. The purpose of this project was to explore specific avenues that S. mutans may use in order to cope with carbohydrate deprivation. Intracellular polysaccharide (IPS) is accumulated by S. mutans when grown in excess sugar, and can contribute towards the cariogenicity of S. mutans. Inactivation of the glgA gene, encoding a putative glycogen synthase, prevented accumulation of IPS in batch cultures grown with excess glucose or sucrose. Inactivation of the pul gene, encoding a putative pullulanase which is thought to be involved in IPS catabolism, did not prevent IPS accumulation. IPS was found to be important for the persistence of S. mutans grown in batch culture with excess glucose, and then starved of glucose. In these conditions, the IPS was largely used up within one day of starvation, and yet survival of the parental strain was extended by at least 15 days beyond that of the glgA and pul mutants; potentially, some feature of IPS metabolism, distinct from providing nutrients, is important for persistence. IPS was not needed for persistence when sucrose was carbon source or when mucin was present in batch cultures. IPS accumulation was not clearly demonstrated in biofilm conditions. When grown in condition permissive for IPS accumulation, biofilms of the glgA and pul mutants did not show decreased survival, compared to the parental strain. It is plausible that, within a biofilm, S. mutans can use alternative sources of energy (like the extracellular matrix) to compensate for the lack of IPS. To look at specific genes upregulated by sugar starvation, microarrays analysis was performed on S. mutans batch cultures. Some of the genes upregulated by starved, stationary phase bacteria, appeared to be organized in an operon, thought to encode components of the pyruvate dehydrogenase (PDH) complex. Northern Blot analysis showed that pdhD and the downstream genes, pdhA, pdhB and pdhC, form an operon that is transcribed predominantly in stationary phase. Inactivation of pdhD impaired survival of both batch cultures and biofilms. Analysis with fluorescent reporters revealed a distinct expression pattern for the pdh promoter, with less than 1% of stationary phase bacteria displaying pdh expression. When first detected, after one day of sugar starvation, expression was in individual bacteria. At later times, expressing bacteria were often in chains. The lengths of chains increased with time suggesting growth and division. It is likely that the pdh-expressing sub-population is able to persist for extend times in stationary phase.
Temple University--Theses
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Tournelle, Kimura Pamela Madeleine. "Prevalencia y diversidad de bacterias pertenecientes al género Streptococcus en saliva de niños pre-escolares chilenos entre 2 y 5 años de edad con y sin caries." Tesis, Universidad de Chile, 2013. http://www.repositorio.uchile.cl/handle/2250/117563.
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Trabajo de Investigación Requisito para optar al Título de Cirujano DentistaIntroducción: La cavidad oral es un ecosistema mixto, formado por diversas especies microbianas, en donde las bacterias cumplen un rol fundamental en el equilibrio salud- enfermedad. Se ha descrito a la caries dental como una de las patologías orales más prevalentes a nivel mundial y se ha observado que especies pertenecientes al género Streptococcus, específicamente al grupo viridans, están fuertemente relacionadas con su desarrollo. S. mutans ha sido una de las especies más asociadas a su inicio y progresión. Sin embargo, esta enfermedad puede ocurrir en ausencia de él y, otras especies pertenecientes a este género, podrían tener una inesperada relevancia en la enfermedad. Objetivo: Determinar la prevalencia y diversidad de especies bacterianas pertenecientes al género Streptococcus en saliva de niños pre-escolares chilenos con y sin caries. Metodología: Muestras de saliva total no estimulada fueron colectadas de la cavidad oral de niños pre-escolares chilenos, entre 2 y 5 años de edad, que presentan caries (10 individuos) o libres de caries (10 individuos), según índice ICDAS II. Se determinó la capacidad tamponante y pH salival, recuento, aislamiento e identificación bacteriana pertenecientes al género Streptococcus. La identificación se realizó mediante test bioquímicos, Reacción en Cadena de la Polimerasa (PCR) y secuenciación de ADN, según corresponda. Resultados: Se observaron diferencias en relación a las especies identificadas en las muestras de sujetos con y sin caries. De los aislados obtenidos de sujetos sin caries, las especies más prevalentes fueron S. salivarius (40%), S. mutans (20%) y S. thermophilus (13,3%) y las especies aisladas en baja proporción correspondieron a S. vestibularis y S. sanguinis (3,3% cada una). De los aislados obtenidos de sujetos con caries, la especie más prevalente correspondió a S. salivarius (73,3%) y las especies encontradas en menor proporción correspondieron a Bacillus subtilis subsp. subtilis (16,7%), S. anginosus y S. mitis (3,3% cada una). Los análisis estadísticos para asociar las variables edad, pH, capacidad tamponante y recuento bacteriano, en relación a prevalencia de caries, resultaron ser no significativos. 2 Conclusiones: Las especies del género Streptococcus y otras especies identificadas, tanto para sujetos con y sin caries, fueron diferentes en cuanto a diversidad. Sin embargo, especies que han sido identificadas como autores principales tanto del desarrollo de caries como de su ausencia, fueron encontradas en baja proporción o no fueron encontradas en este grupo etario. S. salivarius resultó ser la especie aislada con mayor frecuencia en ambos grupos y, parámetros como edad, pH, capacidad tamponante en relación con prevalencia de caries, no fueron significativos. Esto podría revelar que las propiedades cariogénicas y de virulencia de cada especie estarían en íntima relación con las condiciones ambientales y las asociaciones bacterianas que ellas realicen dentro del Biofilm, que una misma especie podría actuar tanto a favor o en contra del hospedero y que un mayor tamaño muestral sería necesario para obtener resultados más concluyentes.
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Armijo, Adonis Jaime Antonio. "“Habilidad vs suerte en el desempeño de fondos mutuos en Chile” — Análisis boostrap del alfa en fondos mutuos de renta variable." Tesis, Universidad de Chile, 2011. http://www.repositorio.uchile.cl/handle/2250/108045.
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This article applies a new methodology to determinate the existence of skill in Chilean equity mutual fund management in 2001-2008. We use bootstrap methodology to distinguish between skill and luck in the ex-post performance of fund. This statistical technique considers the complex non-nomal distribution of cross-sectional alphas due to heterogeneous risk-taking across funds and non-normalities in individual fund alphas distributions
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Ribeiro, Thyciana Rodrigues. "A study of salivary peptide profile in children with early childhood caries: envisioning saliva as a diagnostic tool." Universidade Federal do CearÃ, 2009. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=3576.
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FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgicoThe aim of the present study was to find a relation between salivary peptides, caries experience and mutans streptococci (MS) levels in saliva of caries free (CF) and caries susceptible (CS) children in early childhood. One hundred and six 10 â 71 month-old children participated in the study. Fifty-eight children were CF and 48 who had experienced dental caries formed the CS group. Two samples of whole saliva were collected from all participants. Unstimulated whole saliva was collected, subsequently centrifuged. Supernatants were lyophilized, divided into two pools (CF and CS) and individual samples, and stored at -20oC for posterior analysis using LC-MS (Liquid Chromatography Mass Spectrometry) to study the peptide profile. Identification of salivary peptides was based on theoretical molecular masses available from online databases. Stimulated whole saliva was collected and used for MS detection in MSB agar medium. MS concentration in saliva was reported in cfu/mL. Dental examination was performed and dmfs/dmft scores were calculated. Data was analysed by using logistic regression. The chromatograms from CF and CS pools of saliva had different peak patterns. The identification of molecular masses suggested the presence of 9 peptides. Three of them were significantly related with caries experience. The presence of HNP-3 (α-defensin 3) (p = 0.019) and HBD-3 (β-defensin 3) (p = 0.034) reduced the chances of experiencing early childhood caries (ECC). The presence of PRP IB-4 significantly increased caries experience (p = 0.035). In addition, age (p = 0.020) and MS counts (p = 0.036) increased caries experience, however gender was not associated with dental caries (p = 0.877). Our results suggest that presence of specific peptides in saliva of CF or CS children in early childhood predisposes to a higher or lower risk of caries experience.
Este trabalho buscou estudar o perfil de peptÃdeos salivares de crianÃas com cÃrie da primeira infÃncia, relacionando-o com nÃveis de estreptococos do grupo mutans (EGM) salivares e experiÃncia de cÃrie. Cento e seis crianÃas, na faixa etÃria de 10 a 71 meses de idade, participaram do estudo, sendo 48 com experiÃncia de cÃrie e 58 sem cÃrie da primeira infÃncia. Duas amostras de saliva total foram coletadas de todos os participantes. A primeira amostra era composta de saliva nÃo estimulada, utilizada para anÃlise dos peptÃdeos. ApÃs coletada, essa saliva foi centrifugada, o sobrenadante retirado, liofilizado, dividido em pools com cÃrie, sem cÃrie e em amostras individuais e armazenado em freezer a -20oC atà anÃlise em aparelho de LC-MS (Cromatografia LÃquida acoplado ao EspectrÃmetro de Massa). A busca por peptÃdeos foi baseada em massas conhecidas de peptÃdeos existentes em bancos de dados. Saliva estimulada representou a segunda coleta, utilizada para o cultivo dos EGM (UFC/mL) em meio Ãgar mitis salivarius bacitracina (MSB). Anamnese e exame dentÃrio foram realizados para cÃlculo do Ãndice ceo-s e ceo-d. Os dados foram analisados por meio de modelo logÃstico binÃrio. Resultados foram considerados significantes quando p-valor < 0,05. Os cromatogramas obtidos a partir dos pools de crianÃas com/sem cÃrie apresentaram diferenÃas em relaÃÃo aos picos apresentados. A identificaÃÃo das massas moleculares sugeriram a presenÃa de nove peptÃdeos. RegressÃo logÃstica mostrou que 3 peptÃdeos se relacionaram com experiÃncia de cÃrie. PRP IB-4 associou-se a um aumento de experiÃncia de cÃrie (p=0,035); α-defensina 3 (p=0,019) e β-defensina 3 (p=0,034) associaram-se à reduÃÃo de experiÃncia de cÃrie. Em adiÃÃo, aumento na idade (p=0,020) e aumento na contagem de EGM (p=0,036) ocasionaram um aumento na experiÃncia de cÃrie, mas sexo nÃo se relacionou com cÃrie dentÃria (p=0,877). A partir desses resultados, pÃde-se concluir que a presenÃa de peptÃdeos especÃficos na saliva de crianÃas com e sem cÃrie dentÃria predispÃem a um maior ou menor risco à essa doenÃa.
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Costa, Ana Rosa 1977. "Estudo in vitro do efeito da clorexidina e do etanol na dentina em diferentes condições do substrato dentinário e tempos de armazenagem : Study in vitro the effect of chlorhexidine and ethanol on dentin in different conditions of the dentin substrate and storage times." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/288584.
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Orientador: Regina Maria Puppin RontaniTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
Made available in DSpace on 2018-10-05T18:49:21Z (GMT). No. of bitstreams: 1 Correr_AnaRosaCosta_D.pdf: 3218831 bytes, checksum: f30505368b581fed81781723b234fbd9 (MD5) Previous issue date: 2013
Resumo: O propósito deste estudo foi avaliar a influencia de diferentes tipos de substrato (Capitulo 1) e tratamento com etanol 100% (Capitulo 2) ou digluconato de clorexidina a 2% (CHX) (Capitulo 3) na resistência e longevidade da união compósito/dentina, apos diferentes períodos de armazenagem. Os dentes humanos hígidos foram divididos em 3 grupos, de acordo com o substrato dentinario: (Sd) dentina hígida, (Ci) dentina infectada (manutenção da carie) e (Ca) dentina afetada (remoção parcial de carie). As superfícies oclusais de terceiros molares hígidos foram removidas com disco diamantado dupla face sob refrigeração, a fim de expor a superfície plana dentinaria hígida, a qual foi submetida ao desenvolvimento da lesão de carie artificial com S. mutans. Brocas esféricas foram usadas para remover parcialmente o tecido cariado pigmentado, ate que permanecesse apenas a dentina levemente corada (Ca). Em seguida, os dentes foram novamente subdivididos, de acordo com o tratamento da superfície: Grupo Controle (Ct) - nenhum tratamento (Capitulo 1); Ct e (Et) - aplicação de etanol 100% (Capitulo 2); e, Ct e (CHX) - aplicação de digluconato de clorexidina a 2% (Capitulo 3). O substrato foi condicionado com acido fosfórico a 35% por 15 s, lavado por 30 s e seco com leve jato de ar. CHX ou Et foram aplicados apos o condicionamento acido. O sistema adesivo Adper Single Bond 2 (3M ESPE) foi aplicado de acordo com as recomendações do fabricante e fotoativado por 20 s com a fonte de aparelho de luz XL 2500. Sobre a superfície de união foram inseridos incrementos de 2 mm do compósito Z350 (3M ESPE), polimerizados usando a fonte de luz XL 2500 por 40 s, ate confeccionar um bloco com 6 mm de altura. As amostras foram armazenadas em água destilada a 37o C por 24 horas. Apos, os dentes foram seccionados perpendicularmente a área de união, de modo a obter palitos com área de secção transversal de 1mm2. Os palitos foram armazenadas em três períodos: 24 horas, 6 meses e 1 ano. Em seguida, as amostras foram submetidas ao ensaio de resistência de união a microtração usando a maquina de ensaio EZ test (EZS, Shimadzu) a velocidade de 0,5 mm/minuto. Os dados foram submetidos a Analise de Variância e ao teste de Tukey HSD (?=0,05). A união em Sd mostrou valores de resistência de união significativamente maior quando comparado a Ca e Ci. As amostras armazenadas nos períodos de 6 meses e 1 ano resultou na diminuição da resistência de união, independente do tipo de substrato e/ou tratamento. O etanol não foi efetivo em melhorar a resistência de união para os três substratos de dentina avaliados. A clorexidina não influenciou na resistência de união nos períodos de armazenagem avaliados, independente dos substratos
Abstract: The aim of this study was to evaluate the effect of 2% chlorhexidine digluconate (CHX) and 100% ethanol wet-bonding (Et) on the degradation of the adhesive system bond strength in sound or artificial caries-affected/infected dentin after different storage times under microtensile test (_TBS). The sound teeth were divided into 3 groups, according to dentin substrates: sound dentin, caries-infected dentin (maintained of caries) and caries-affected dentin (partial removal of caries). Non-carious human third molars had their occlusal enamel removed with a slow speed diamond saw, under copious water-cooling to expose a flat-surfaced sound dentin, which was submitted to the microbiological challenge (S. mutans) for the development of artificial caries. Spherical drill was used to remove soft pigmented carious tissue till hard and slightly pigmented dentin remains (Ca). After, the teeth will be assigned into 3 subgroups according to surface treatment: water wet- bonding (Ct) (Chapter 1); Ct and 100% ethanol application (Et) (Chapter 2); and, Ct and chlorhexidine digluconate 2% application (CHX) (Chapter 3). The substrate will was etched with 35% phosphoric acid gel for 15 s, rinsed for 30 s with tap water and dried with oil/water-free air. The CHX or Et was applied for 60 s, just after etching with 35% phosphoric acid gel. The adhesive system Adper Single Bond 2 (3M ESPE) was applied according to the manufacturer's instruction and polymerized for 10 s by a light-curing unit XL 2500. The bonded surfaces were coupled with a composite resin Filtek Z350 (3M ESPE) applied in 2 mm increments and polymerized using a curing unit XL 2500 (3M ESPE) for 40 s for each increment and to build 6 mm thick block. The restored teeth were stored in distilled water at 37o C for 24 h. After this period, the restored teeth were longitudinally sectioned across the bonded interface to produce a series of 1.0mm2 beams. The specimens were then submitted to three storage periods: 24 hours, 6 months, or 1 year. Afterwards, the storage periods, the specimens were submitted to a microtensile bond strength (_TBS) using EZ test machine (EZS, Shimadzu) at a crosshead speed of 0.5 mm/min until failure. Data were submitted to ANOVA and Tukey's HSD test (?=0.05). The bonding with sound dentin showed _TBS values significant higher when compared to caries-affected and caries-infected dentin. The 6 months and 1 year storage periods resulted in decreased bond strengths for all dentin conditions and/or treatment. The ethanol was not effective to improve the _TBS for the three dentin substrates evaluated. The CHX did not affect the 24- hour, 6 and 12 months _TBS, independent of the tested dentin substrates
Doutorado
Materiais Dentarios
Doutora em Materiais Dentários
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Hale, John D. F., and n/a. "Small bacteriocins produced by Streptococcus mutans and Streptococcus sanguis." University of Otago. Department of Microbiology & Immunology, 2006. http://adt.otago.ac.nz./public/adt-NZDU20060905.144149.
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Dental caries is the most common bacterial disease of humans and occurs when oral bacteria produce acids, following their fermentation of dietary carbohydrates. This acid can then cause a localised demineralisation of the tooth surface. A group of seven species of bacteria, collectively known as the mutans streptococci, have been predominantly implicated in the onset of dental caries. In particular, Streptococcus mutans and Streptococcus sobrinus have been shown to be the main aetiological agents of this disease in humans. Most attempts to control the microbial component of caries target these bacteria.
The past 50 years has provided considerable information about the pathogenesis of dental caries, the likely route and time of transmission of cariogenic bacteria to susceptible hosts and possible ways of either treating or controlling the onset of this disease. In regards to the latter, many techniques (such as the use of tooth brushes, mouth washes, dental floss and tooth paste) for the control of plaque build-up exist and the examples listed are generally part of a daily routine. However, these techniques need to be applied regularly, and as such only highly-motivated individuals generally experience improved oral health. Therefore, the search for more effective less labour-intensive approaches continues. One area of research is into the potential application of small ribosomally-synthesised antimicrobial peptides, known as bacteriocins. Bacteriocins generally inhibit closely-related species that occupy the same ecological niche. Their relatively-specific targeting, plus the fact that many are remarkably heat and chemically-stable molecules, makes them excellent candidates for possible anti-caries applications.
Numerous bacteriocins produced by the lactic acid bacteria have now been identified. Most can be broadly categorised into one of four main classes, of which Class I, the lantibiotics and Class II, the small (<10 kDa) non-modified peptides, contain the most examples. Many screens for anti-mutans streptococcal (MS) bacteriocins have been carried out and it appears that the best source of anti-MS bacteriocins are the mutans streptococci themselves. Research in this laboratory has identified examples of anti-mutans streptococcal bacteriocins produced by both mutans streptococci and non-mutans streptococci. The present study investigated the anti-MS inhibitors produced by two streptococcal strains, S. mutans N and Streptococcus sanguis K11. During the course of this study a third strain, S. mutans UA159, was also studied for its bacteriocinogenic properties.
Although S. sanguis K11 produces anti-mutans streptococcal inhibitory activity, this appears only effective against Streptococcus rattus. In addition however, the inhibitory activity of this strain is also directed against all tested strains of Streptococcus agalactiae and ca. 50% of Streptococcus pyogenes. In the present study a 5069 Da novel inhibitory agent (sanguicin K11) was characterised and shown responsible for this unusual inhibitory spectrum. Through reverse genetics the sanK11 locus was identified and shown to encode a Class II type bacteriocin, the first shown to be produced by S. sanguis. Following screens of additional S. sanguis, sanK11 was shown to be present only in strains producing the same type of inhibitory pattern (P-type) as strain K11. The cysteine residues at positions 7 and 38 of the sanguicin K11 propeptide were shown to form a disulphide bridge essential for sanguicin K11 inhibitory activity.
S. mutans N and eight other S. mutans strains have been found to have what appears to be the same inhibitory spectrum, which includes members of the mutans streptococci and several other oral streptococcal species. One strain (UA140) of the eight has previously been shown to produce the lantibiotic mutacin I and the non-lantibiotic mutacin IV. S. mutans N was known to produce the non-lantibiotic mutacin N. The current study set out to investigate how two strains, apparently producing completely different bacteriocins could have the same inhibitory spectrum. Reverse genetics identified the mutacin N structural gene (mutN) and mutagenesis studies showed that this bacteriocin was responsible only for the inhibitory activity against mutans streptococci. Further sequencing around the mutN locus identified a second bacteriocin-like locus (mutO) adjacent to mutN. mutO was also identified to have anti-mutans streptococcal inhibitory activity and because of the close proximity of mutO and mutN and given the homology they share with other known two-peptide bacteriocins it seemed probable that mutacins O and N are components of a new member of this special class of bacteriocins (Class IIb, the two peptide bacteriocins) in which the optimal inhibitory activity is dependent on the co-operative activity of the two peptides.
Further investigations of strain N examined the expression of mutacins O and N. During a search for a suitable heterologous non-mutacinogenic S. mutans strain to act as an expression host, the genome reference strain, S. mutans UA159 was given consideration. However, contrary to previous reports, this strain was found to exhibit bacteriocin-like inhibitory activity. During a follow-up investigation, strain UA159 was found to inhibit 84 strains representing 11 different species of bacteria, but no inhibition of mutans streptococci was detected. The locus (nlmAB) encoding the two-peptide bacteriocin mutacin IV was identified within the UA159 genome. Using genetic dissection of nlmA and nlmB, the contribution of each peptide was examined and it was found that only the NlmA* propeptide appears to be active, raising doubts as to whether mutacin IV is a bona fide two-peptide bacteriocin. Deletion of the entire nlmAB locus created a mutant strain that exhibited a loss of inhibitory activity against the same 64 strains as was found for the nlmA mutant. A BLASTP search for the consensus leader sequence that precedes the propeptide of Class II bacteriocins, identified ORFs encoding 9 more putative bacteriocin-like peptides. Further genetic dissection identified the SMU.1914c locus as being responsible for the inhibitory activity against a further 15 strains not already sensitive to mutacin IV. SMU.1914c was renamed mutacin V. However, it appears that another as yet unidentified mutacin(s) is also produced by strain UA159 given that three indicator strains still remained sensitive to a double mutant [UA[Delta](1914/NlmAB)] in which both the mutacin IV and putative mutacin V loci were inactivated.
Export of Class II bacteriocins has been found to occur by either a SEC-dependent system or via a dedicated peptide ATP Binding Cassette (ABC) transporter. Three potential ABC transporter ORFs were identified in S. mutans UA159. Two (comA and cslA) had the characteristic accessory factor ORF (comB and cslB respectively) located adjacent to the main ABC transporter ORF, while the third ORF763 appeared to lack this. Mutagenesis of each of these five ORFS was carried out and confirmed cslAB to be the ABC transporter involved in the export of the competence stimulating factor, while the function of ORF763 could not be established in this study. Mutagenesis of either comA or comB resulted in a complete cessation of bacteriocin production by the respective mutant strains. Historically, comA and comB is the nomenclature used for loci encoding the exporter of the competence inducing factors in streptococci. In light of this new information, comA and comB were renamed nlmT and nlmE respectively, to account for the newly defined role of this ABC transporter.
The present study investigated four bacteriocins two of which (sanguicin K11 and mutacin ON) appear to have some potential for application to anti-caries control, and the others (mutacins IV and V) being shown to be produced by the genome reference strain (UA159). All three mutacins were shown to be exported from their respective producer cells by the NlmTE ABC transporter, while sanguicin K11 is predicted to be exported by a peptide ABC transporter located adjacent to sanK11.
Bacteriocins may yet provide a novel alternative for the treatment and control of dental caries. In their favour is that fact that they have relatively narrow defined inhibitory spectra and thus are unlikely to produce widespread changes to plaque ecosystems. Potential uses include as topical agents where bacteriocin preparations could be incorporated into dentrifices such as toothpastes or mouthwashes. Alternatively, streptococci producing anti-mutans streptococcal bacteriocins could be implanted into the oral cavity in strain replacement therapy strategies. There are pros and cons to each technique and the most effective anti-caries control appears more likely to result from "cocktail therapy" where bacteriocins are combined with a number of other anti-mutans streptococcal agents to achieve long-lasting protection against mutans streptococcus proliferation.
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Protheroe, R. G. "The interaction of Streptococcus mutans with hard collecting surfaces." Thesis, University of Bristol, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375404.
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Bruyère, Thierry. "Etude immunologique et génétique d'une adhésine de Streptococcus mutans." Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37603507w.
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Wennerholm, Kerstin. "Influence of sugar and sugar alcohols on mutans streptococci." Göteborg, Sweden : Göteborg University, 1994. http://books.google.com/books?id=Sq1pAAAAMAAJ.
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Holtman, Catherine E. "Rapid Detection of Streptococcus mutans in Saliva." Digital Commons @ East Tennessee State University, 2012. https://dc.etsu.edu/etd/1460.
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Documentation exists that mothers can pass the cariogenic bacteria Streptococcus mutans to their infants. The newest technology to identify Streptococcus mutans is a rapid detection saliva test. Two hundred patients above the age of 18 were targeted using random selection in a Louisville, Kentucky dental office. Patients signed an informed consent form and were given a qualifying questionnaire. Patients received 2 bitewing x-rays and a charted DMFT index and were administered the saliva test. While the null hypothesis was rejected using the chi square test, the results were inconclusive due to expected values. However, other chi square results revealed that the test worked or had the potential to work. Furthermore, it was concluded that the test had high specificity. Further research is warranted; however, the saliva test in combination with the DMFT and x-rays are instrumental tools for the dental professional in educating patients and prevention.
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González, Parro Diego, Allendes Sebastián Ochagavía, and Allende Matías Sánchez. "Estudio del “efecto disposición” en los fondos mutuos chilenos." Tesis, Universidad de Chile, 2011. http://repositorio.uchile.cl/handle/2250/108060.
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This paper seeks to analyze and identify the known disposition effect in the Chilean mutual funds management. Mainly consists of 5 sections, which first prepares the reader with terms and definitions for a better understanding of the topic, then cover work related to research that has been used as references for our research. The following explains the methodology used to explain in detail the collection of databases and programs to develop the theme chosen, the model with their results and validation statistics and finally we conclude about the lack of empirical presence of the effect and possible explanations.
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Silva, Thiago Cruvinel da. "Estudo dos efeitos da terapia fotodinâmica sobre Streptococcus mutans." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/25/25145/tde-18082010-104126/.
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Este estudo teve por objetivos (1) estudar os efeitos de diferentes parâmetros de terapia fotodinâmica sobre a viabilidade de células planctônicas e biofilme de S. mutans UA159, (2) verificar a viabilidade de uso de um modelo para crescimento de biofilme bacteriano no estudo do processo de desmineralização, (3) avaliar a capacidade da terapia fotodinâmica em controlar o processo de desmineralização mediado por biofilme de S. mutans crescidos sobre discos de dentina bovina e (4) mensurar a capacidade da terapia fotodinâmica em promover estresse celular a S. mutans UA159 com deleção do gene VicK. Os procedimentos de terapia fotodinâmica foram realizados pela associação do fotossensibilizador Photogem® e de um LED vermelho visível (Biotable®, 630 nm, 50 mW/cm2) como fonte de luz. A viabilidade de células bacterianas foi determinada por dois métodos distintos: teste de atividade metabólica pelo uso da resazurina (etapa 1) e contagem de UFC (etapas 1,2 e 3). Microrradiografia transversal e análise da concentração de cálcio por espectrometria de absorção atômica foram os métodos de escolha para a determinação do perfil do conteúdo mineral (%vol), perda mineral integrada (PMI, %vol x m), profundidade de lesão (PL, m) e concentração de cálcio liberado em meio de cultura (mg/dL). A intensidade de fluorescência emitida pela modulação da proteína GFP após ensaio de estresse celular foi determinada por citometria de fluxo. Os diferentes parâmetros de terapia fotodinâmica foram capazes de reduzir a viabilidade de células planctônicas de S. mutans, bem como das células organizadas em biofilme (ANOVA a um critério, Games-Howell, p<0,05), sendo o resultado dose-dependente. Quando Photogem® a 0,25 mg/mL foi associado ao LED a 150 J/cm2, uma redução de aproximadamente 3,9 log10 na contagem de células viáveis provenientes de biofilme foi observada. O modelo para crescimento de biofilme permitu a progressão do processo de desmineralização (24 h PMI: 1905±391 vol% x m, PL: 69,9±12,2 m; 48 h - PMI: 3529±886 vol% x m, PL: 114,2±24,6 m; 72 h - PMI: 4186±1099 vol% x m, PL: 146,1±20,1 m) em função do tempo. As associações de Photogem® 0,25 mg/mL + LED 75 J/cm2 e Photogem® 0,25 mg/mL + LED 150 J/cm2 foram capazes de controlar por 24 h a perda mineral integrada, a profundidade de lesão e a concentração de cálcio liberada em relação ao grupo controle (ANOVA a um critério, Games-Howell, p<0,05). Os diferentes tipos de tratamento utilizados no ensaio de estresse celular (H2O2 a 0,0025%, H2O2 a 0,005%, Photogem® a 0,00625%, Photogem® a 0,0125%, LED 4,5 J/cm2, Photogem® a 0,00625% + LED 4,5 J/cm2 e Photogem® a 0,0125% + LED 4,5 J/cm2) produziram aumento significativo da fluorescência captada pela citometria de fluxo em relação ao grupo controle (água deionizada) (ANOVA a um critério, Games-Howell, p<0,05). Entretanto, diferenças significativas não foram notadas entre os grupos de tratamento. Portanto, a terapia fotodinâmica foi capaz de reduzir a viabilidade de células planctônicas e células organizadas em biofilme (S. mutans UA159), bem como controlar o processo de desmineralização mediado por bactéria durante 24 h. Além disso, pelo modelo utilizado, a terapia fotodinâmica pode ser capaz de modular estresse celular comparável àquele obtido com a utilização do peróxido de hidrogênio em diferentes concentrações.The present study aimed (1) to assess the effects of different parameters of Photodynamic Antimicrobial Chemotherapy (PACT) on the viability of planktonic cells and biofilm of S. mutans UA159, (2) to test the effectiveness of a biofilm model in evaluating the demineralization process, (3) to assess the influence of PACT on the control of demineralization process mediated by S. mutans biofilm growth on dentin discs, and (4) to measure the ability of PACT in promoting cellular stress on S. mutans UA159 knockout vicK gene. PACT procedures were performed by association between a photosensitizer (Photogem®) and a visible red LED (Biotable®, 630 nm, 50 mW/cm2) as light source. Viability of bacterial cells was determined by two distinct methods: resazurin assay (phase 1) and Colony Forming Unit (CFU) counts (phases 1, 2, and 3). Transversal microradiography and calcium release analysis by atomic absorption spectrometry were chosen to analyze mineral content profile (%vol), integrated mineral loss (IML, %vol x m), lesion depth (LD, m), and concentration of calcium release in culture media (mg/dL). Fluorescence intensity levels, which were modulated by expression of Green Fluorescent Protein-reporter (GFP) after cellular stress, were measured by flow cytometer. A dose-dependent effect on the reduction of viability of planktonic cells and biofilm of S. mutans was observed after application of different parameters of PACT (one-way ANOVA, Games-Howell, p<0.05). 0.25 mg/mL Photogem® plus 150 J/cm2 LED decreased in nearly 3.9 log10 the viability of S. mutans biofilm. Progression of demineralization process was correlated with the time (24 h IML: 1905±391 vol% x m, LD: 69.9±12,2 m; 48 h - IML: 3529±886 vol% x m, LD: 114.2±24.6 m; 72 h - IML: 4186±1099 vol% x m, LD: 146.1±20.1 m). Integrated mineral loss, lesion depth and concentration of calcium release were controlled for 24 h by the following associations: 0.25 mg/mL Photogem® plus 75 J/cm2 LED, and 0.25 mg/mL Photogem® plus 150 J/cm2 LED, in comparison to control group (one-way ANOVA, Games-Howell, p<0.05). Different treatments (0.0025% H2O2, 0.005% H2O2, 0.00625% Photogem®, 0.0125% Photogem®, 4.5 J/cm2 LED, 0.00625% Photogem® plus 4.5 J/cm2 LED, and 0.0125% Photogem® plus 4.5 J/cm2 LED) increased significantly the fluorescence levels emitted by S. mutans, when compared with levels of the control group (demi water) (one-way ANOVA, Games-Howell, p<0.05). However, significant statistical differences were not observed among treatment groups. Therefore, PACT was able to decrease the viability of planktonic cells and biofilm of S. mutans UA159, as well as controlling the demineralization process mediated by bacteria for 24 h. Moreover, according to present methods, PACT may modulate cellular stress similar to hydrogen peroxide.
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Moreira, Monica. "Métodos de detecção e caracterização molecular de Streptococcus mutans." reponame:Repositório Institucional da UFPR, 2012. http://hdl.handle.net/1884/53998.
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Orientadora : Profª. Drª. Vânia Aparecida VicenteTese (doutorado) - Universidade Federal do Paraná, Setor de Tecnologia, Programa de Pós-Graduação em Engenharia de Bioprocessos e Biotecnologia. Defesa: Curitiba, 24/07/2012
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Resumo; A cárie é uma doença infecciosa, determinada por diversos fatores endógenos e exógenos ao indivíduo. O principal agente etiológico relacionado à doença é a bactéria Streptococcus mutans, devido a fatores de virulência como capacidade de aderir-se ao esmalte dental e propiciar a formação do biofilme dental, através da produção de polissacarídeos extracelulares. Os exopolissacarídeos, que são glucanos sintetizados a partir da enzima glicosiltranferase, promovem sítios de acumulação de microrganismos na superfície dental, e são enzimaticamente ativos quando expostos a sacarose da dieta. Dentro deste contexto, o objetivo geral deste trabalho foi caracterizar S. mutans por meio de marcador molecular, utilizando o sequenciamento parcial do gene gtfB que codifica a enzima Betaglicosiltransferase, e detectar o microrganismo por meio de sonda baseada na metodologia de amplificação em círculos rolantes (Rolling Circle Amplification - RCA). Para o isolamento do DNA genômico de bactérias do gênero Streptococcus, dois métodos de extração utilizando brometo de cetil trimetil amônio (CTAB) foram testados. O método que associou o ultrasson à sílica e celite foi mais eficiente. Com o objetivo específico de identificar a variabilidade genética e a relação de isolados de S. mutans com o perfil de colonização e epidemiologia da doença cárie na população infantil, linhagens isoladas da saliva de crianças com diferentes históricos de cárie, foram caracterizadas por marcadores RAPD (Random Amplified Polymorphic DNA), e sequenciamento de regiões específicas do gene que codifica a enzima Beta-glicosiltransferase (gtfB). Os resultados demonstraram que a variabilidade genética dos isolados pode estar relacionada ao padrão de virulência, justificando assim, as variações observadas nos níveis de colonização dos indivíduos e manifestação clínica da doença. Com o objetivo de identificar a transmissibilidade intrafamiliar de S. mutans isolados procedentes de saliva de indivíduos pertencentes a duas famílias de alto risco biológico e social, previamente caracterizados por marcadores RAPD, foram estudados quanto à variabilidade genética de uma região do gene que codifica a enzima Beta-glicosiltransferase (gtfB). Os resultados revelaram transmissibilidade de isolados intrafamiliar e relação entre sorotipos e virulência. Visando estabelecer um método de detecção direta para S.mutans, uma sonda cadeado (padlock) RCA foi desenvolvida a partir de sequências intergênicas 16S-23S rDNA de S. mutans, e associada ao método de amplificação isotérmica do DNA total em círculos rolantes (RCA). A sonda foi testada em diferentes amostras de DNA, incluindo isolados S. mutans procedentes de indivíduos com diferentes históricos da doença, linhagens referência do gênero, além de amostras de biofilme dental e saliva. O método demonstrou ser efetivo para a detecção de S.mutans, apresentando alta especificidade em relação a outras espécies do grupo mutans. Palavras-chave: Streptococcus mutans; cárie; RAPD; região intergênica; gtfB; RCA; sonda padlock.
Abstract: Dental caries is an infectious disease that can be greatly affected by the endogenous and exogenous conditions within each individual host. The main etiological disease - related agent is the bacterium Streptococcus mutans, due to its virulence factors such as ability to adhere to the tooth's enamel and lead to biofilm formation, through the production of extracellular polysaccharides. Exopolysaccharides, which are glucans synthesized from the enzyme Glucosyltransferases, promote the accumulation of microorganisms at specific sites on dental surfaces and become enzymatically active when exposed to dietary sucrose. In this context, the aim of this study was to characterize S. mutans through molecular markers, by using the partial sequencing of the gtfB gene and detect the microorganism using probe-based RCA methodology. In this work, genomic DNA from Streptococcus bacteria was isolated through two methods of extraction using cetyltrimethylammonium bromide detergent (CTAB). The composite method that used ultrasound was the most efficient, allowing the straightforward extraction of genomic DNA from Gram-positive bacteria with good quality and reproducibility. In order to characterize the genetic variability of various S. mutans isolates and to correlate this variability with different colonization profiles observed during dental caries in a sample of children, S. mutans samples were isolated from saliva of children with several histories of dental caries. Initially selected by RAPD (Random Amplified Polymorphic DNA) markers, they were characterized by sequencing a specific region of the gene encoding the enzyme betaglucosyltransferase (gtfB).The results indicated the existence of genetic variability that could be related to the virulence pattern, thus justifying the variations observed in the levels of colonization of individuals and clinical manifestation of the disease. The specific aim was identifying the intrafamilial transmission of salivary isolates of S. mutans in individuals belonging to two families with high biological and social risk. Initially characterized by RAPD markers, those S. mutans were characterized by genetic variability of a specific region of the gene encoding the enzyme betaglucosyltransferase (gtfB). The results revealed the transmissibility among isolates within families and relationship between sorotipes and virulence. Aiming to establish a direct detection method for S. mutants, a padlock-RCA (Rolling circle amplification) probe was developed from the sequence analysis of intergenic 16S-23S rDNA of S. mutans, associated with the isothermal method of Rolling Circle Amplification (RCA) of the total DNA. The probe was tested in different samples of DNA, including isolates of S. mutans proceeding from individuals with different disease history, reference strains of the genus, beyond biofilm and saliva samples. The method was effective for detection of S. mutans isolates, with high specificity in relation to other species of mutans group. Key words: Streptococcus mutans; caries; RAPD; intergenic region; gtfB; RCA; padlock probe.