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Made available in DSpace on 2014-06-11T19:27:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-06-05Bitstream added on 2014-06-13T20:35:49Z : No. of bitstreams: 1 cardoso_pa_me_jabo.pdf: 283666 bytes, checksum: 9d4635249701354d18b4a667c65f5861 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O objetivo deste estudo foi investigar a ocorrência de cepas de Escherichia coli produtoras de Shiga toxina (STEC) em queijos mussarela produzidos artesanalmente. Foram analisadas 59 amostras de queijo, produzidas no Vale do Jequitinhonha (Nordeste de Minas Gerais, Brasil). Isolando-se 147 cepas de E. coli e através da técnica de PCR, foram investigadas a presença dos genes da Shiga toxina (stx 1 e stx 2) e da intimina (eae). Dezesseis cepas bacterianas (10,8%) apresentaram o gene stx ( todas portavam o gene stx 1) e 13 delas também se mostraram eae positivas. Os isolados de E. coli foram também examinados para a detecção dos genes codificadores de adesinas (pap, sfa e afa). Não foram identificados nenhum desses genes.Todas as cepas STEC isoladas foram pesquisadas para resistência a 12 agentes antimicrobianos. As resistências predominantes detectadas foram de 37,5% para estreptomicina, 37,5% para a tetraciclina, 31,2% para a ampicilina e 31,2% para a amicacina. A resistência a múltiplas drogas foi encontrada em 5 cepas (31,2%). A presença dos genes codificadores dos fatores de virulência indica que o queijo mussarela produzido artesanalmente pode representar um risco à saúde dos consumidores. / The aim of the present study was to investigate the occurrence of Escherichia coli strains presenting the Shiga toxin gene (probably STEC strains) in mussarela cheese produced by artesanal method in the Jequitinhonha Valey (Northeast of Minas Gerais State, Brazil). Fifty-nine cheese samples were analyzed and a hundred forty seven strains of E. coli were isolated. Using the PCR method the strains were screened for the Shiga toxin (stx 1 and stx 2) and the intimin (eae) genes. Sixteen isolates (10,8%) carried the stx gene (all of them showed the stx 1 gene ) and thirteen also presented the eae gene. Using the same method the strains were screened for the presence of pap, afa, and sfa genes, adhesin genes caracteristics of the E. coli extraintestinal pathogenic strains (ExPEC). None of them showed these adhesin genes and could not be classified as an ExPEC strains. The susceptibility of the probably STEC strains to twelve antimicrobial drugs were evaluated. The most important resistance was detected to the streptomycin (37,5%), tetracycline (37,5%), ampicillin (31,2%) and amikacin (31,2%). The multidrug resistance was detected in 5 isolates (31,2%). The presence of coding genes for virulence factors in the E. coli isolates recovered from mussarela cheese produced by artesanal method could represent a risk for the human health.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-01-07T13:29:52Z No. of bitstreams: 1 maluegidiodasilveira.pdf: 1270797 bytes, checksum: c6aeb32eed6132e545ad6c185c1b11ea (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-01-25T16:45:14Z (GMT) No. of bitstreams: 1 maluegidiodasilveira.pdf: 1270797 bytes, checksum: c6aeb32eed6132e545ad6c185c1b11ea (MD5) / Made available in DSpace on 2016-01-25T16:45:14Z (GMT). No. of bitstreams: 1 maluegidiodasilveira.pdf: 1270797 bytes, checksum: c6aeb32eed6132e545ad6c185c1b11ea (MD5) Previous issue date: 2015-02-24 / Entende-se por engajamento escolar o nível de envolvimento do aluno em atividades escolares, sendo composto em quatro dimensões: comportamental, cognitiva, emocional e agente. Na realidade brasileira, existem poucos instrumentos específicos e com evidências de validade para medir o engajamento escolar. O presente estudo teve como objetivos adaptar e obter evidências de validade da escala EAE-4DE para o contexto brasileiro, bem como relacionar os tipos de engajamento com o desempenho acadêmico e a compreensão de leitura. Participaram da pesquisa 258 estudantes do 6º ano do ensino fundamental, de escolas públicas e privadas. A adaptação da escala EAE-4DE foi satisfatória com base na análise de juízes, em que o índice Kappa de concordância foi de 0,956, e, também foram obtidas evidências de validade com base na análise fatorial. As medidas de engajamento escolar consideradas em conjunto não apresentaram relação significativa com a compreensão de leitura, porém apresentaram uma relação próxima à moderada com a média escolar. / The term school engagement is understood as the level of student’s involvement in school activities, consisting in four dimensions: behavioral, cognitive, emotional and agent. In Brazilian reality, there are few specific tools and evidence of validity to measure school engagement. This study aimed to adapt and bring evidence of validity of EAE - 4DE scale for the Brazilian context as well as relate the types of engagement with the academic performance and reading comprehension. 258 students from the 6th grade of private and public elementary schools took part in the study. The adaptation of EAE - 4DE scale was satisfactory based on the judges’ analysis, in which Kappa index of concordance was 0,956, also obtained evidence of validity based on factor analysis. The school engagement measures taken together showed no significant relationship with reading comprehension, despite they showed a close to moderate relationship with the school average.

No description available.

Self-reactive CD4+ helper T cells (Th) are key causal agents in the pathogenesis of many autoimmune diseases. Experimental autoimmune encephalomyelitis (EAE) is a CD4+T cell model of the demyelinating autoimmune disease multiple sclerosis (MS). It has been shown that EAE is caused by CD4+ T-cells that produce pro-inflammatory cytokines IFN-γ (Th1) and IL-17 (Th17). As such, understanding how these Th cells are generated and controlled is essential. There is debate as to whether Th1 and Th17 cells act independently in EAE or if there is plasticity between these two subtypes, and whether the capacity to switch from Th1 to Th17 confers pathogenic capacity. T-bet was first described as the master transcription factor for Th1 cells, and is thought to have a critical role in EAE even though IFN-γ, the Th1 archetypal cytokine, has been shown to be redundant. More recent work has shown that T-bet is expressed in multiple immune cell types, and it remains unclear in what cells the expression of T-bet is required for EAE. Considerable efforts have been put into understanding the role of T-bet in EAE pathogenesis, with a view to modulate cells expressing T-bet for therapy. The hypothesis of this work was that T-bet has multifaceted roles in EAE, in initiating and directing an immune response in innate antigen presenting cells such as dendritic cells (DC) as well as programming pathogenic effector CD4+ T cell (Teff) response to antigen. T-bet-/- mice were studied using different models of EAE to dissect the role of T-bet in disease pathogenesis. Active immunisation of C57BL/6 mice with the immunodominant peptide from myelin oligodendrocyte glycoprotein (MOG35-55) showed that T-bet-/- mice developed EAE with an IL-17 dominated profile and critically, T-bet-/- mice were able to produce GM-CSF which has recently been described as a key cytokine for EAE. T-bet-/- cells were not able to transfer EAE in a model of passive transfer EAE, where CD4+ T cells were polarised towards a Th1 profile in vitro. Illustrating that T-bet is required in CD4+ T cells for Th1 mediated EAE. DC driven EAE showed that T-bet-/- DC were able to activate CD4+ T cells in vitro and cause EAE upon co-transfer into host mice with transgenic CD4+ T cells. Thus, it has been shown that T-bet is not required in EAE. This work represents a step further towards understanding the disease mechanisms involved in EAE and suggests T-bet is not an appropriate therapeutic target for the treatment of MS.

Axonal pathology is a key contributor to long-term disability in multiple sclerosis (MS), an inflammatory demyelinating disease of the central nervous system (CNS), but the mechanisms that underlie axonal insults remain unclear. While most axonal pathologies characterized in MS are a direct consequence of myelin loss, we propose that axonal pathologies also occur independent of demyelination. In support of this idea, we recently reported that mice that develop experimental autoimmune encephalomyelitis (EAE), a model commonly used to mimic the pathogenesis of MS, exhibit a structural and functional disruption of the axon initial segment (AIS), a subdomain of the axon that acts as the trigger-zone for action potential generation. Importantly, this disruption is independent of myelin loss. Although the mechanism responsible for AIS disruption remains unclear, we observed an attenuation of the AIS insult following treatment with a known scavenger of oxygen free radicals. To further investigate the role of oxidative stress in modulating AIS stability, we employed an in vitro model in which neurons were exposed to a spontaneous reactive oxygen and nitrogen species generator. Through this approach, we demonstrated that oxidative stress is capable of AIS modulation acting through induction of cytosolic calcium (Ca2+) influx from both extracellular and intracellular sources, resulting in calpain protease activation. Furthermore, because rises in intracellular Ca2+ are central to these and other mechanisms of AIS disruption, we next investigated the cisternal organelle (CO), an AIS-localized Ca2+-regulating structure. Although this organelle could prove to be central to AIS modulation, very little is known about the mechanisms regulating its stability. Through this line of investigation, we provide the first evidence of pathological alteration to the CO in a disease state. This disruption precedes loss of AIS protein clustering and axo-axonic GABAergic input in both EAE and MS postmortem tissue. Overall, these studies reveal a primary axonal insult, independent of myelin loss, in a disease classically characterized as a white-matter pathology. Instead, this insult is most likely driven by oxidative stress through local Ca2+ dysregulation at the AIS, providing novel therapeutic targets for MS.

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A healthy immune system's core challenge is to mount appropriate responses to an immense and unknown variety of antigenic stimuli. By unraveling the regulatory networks that drive and control immune-cell behaviors, we can begin to identify the means by which proper balance can be achieved and aberrant behaviors clinically corrected. Traditionally, major advances in our understanding of cellular immunological processes depended critically on both improved perturbation and enhanced observation methods. In my doctoral research, I have pursued both strategies to elucidate the differentiation and effector functions of adaptive immune Th17 cells. These cells exemplify the need for balance: while Th17 cells are needed to induce clearance of fungal infections and extracellular bacteria, irregular responses have been strongly implicated in autoimmunity. / Chemistry and Chemical Biology

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Aus klinischen Studien ist bereits bekannt, dass die aus der Christrose (Helleborus purpurascens) isolierte makrozyklische Substanz MCS-18 in der Lage ist, eine pathologisch aktivierte Immunreaktion wie die rheumatoide Arthritis zu unterdrücken. In der vorliegenden Arbeit stand die Untersuchung der immunmodulatorischen Wirkung von MCS-18 auf dendritische Zellen (DZ) im Vordergrund. Um eine potente Immunantwort zu induzieren, müssen DZ reifen. Hier konnte in vitro gezeigt werden, dass MCS-18 in der Lage ist, die Expression der typischen Reifungsmarker wie CD80, CD86 und vor allem CD83 zu unterdrücken. Darüber hinaus konnte in vitro eine konzentrationsabhängige Reduktion der DZ- T-Zell - Clusterbildung und eine Blockade der DZ-vermittelten T-Zell Stimulation nachgewiesen werden. Im weiteren Verlauf der Arbeit konnte zusätzlich eine dosisabhängige Reduktion der DZ-unabhängigen, anti-CD3/anti-CD28-vermittelten T-Zell Stimulation gezeigt werden. Ferner konnte eine konzentrationsabhängig reduzierte CCR7 -Expression auf der Oberfläche behandelter DZ und daraus resultierend eine eingeschränkte Migrationsfähigkeit der DZ entlang eines CCL19-Gradienten nachgewiesen werden. In vivo besitzt MCS-18 das Potential, die der EAE (ein Mausmodell der humanen Multiplen Sklerose) assoziierten Paralysesymptome sowohl bei prophylaktischer als auch bei einer realen Verhältnisse am nächsten kommenden therapeutischen Gabe zu reduzieren. Selbst bei der Induktion einer zweiten EAE konnte ein lang anhaltender immunsupprimierender Effekt von MCS-18 festgestellt werden. Am bedeutendsten für eine potentielle spätere therapeutische Anwendung am Menschen ist jedoch die Tatsache, dass MCS-18 auch oral verabreicht wirksam bleibt. Histologisch konnte bei mit MCS-18 behandelten Mäusen eine stark reduzierte Infiltration des Gehirns und Rückenmarks mit CD45+ Leukozyten nachgewiesen werden. Zusammengefasst zeigen sowohl die in vitro als auch die in vivo gewonnenen Daten das große therapeutische Potential von MCS-18 für die Therapie von autoimmunen oder anderen immunbedingten Erkrankungen auf.