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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
131

Identificação de proteases de Leptospira envolvidas com mecanismos de escape do sistema complemento humano. / Identification of leptospiral proteases involved in immune evasion mechanisms from the human complement system.

Tatiana Rodrigues Fraga 01 August 2014 (has links)
A leptospirose é uma zoonose causada por leptospiras patogênicas. Para estabelecer a infecção, estas bactérias desenvolveram estratégias de escape ao sistema complemento. Neste trabalho demonstramos que o sobrenadante de cultura de leptospiras patogênicas é capaz de inibir as três vias do complemento. Observamos que esse sobrenadante possui atividade proteolítica sobre C3, C3b e iC3b, além do FB (via alternativa), C2 e C4b (via clássica e das lectinas). As proteínas C3, C4, C2 e FB também foram clivadas quando soro humano normal (SHN) foi utilizado como fonte de complemento. Demonstramos que as proteases atuam em conjunto com os reguladores do hospedeiro Fator I e Fator H na clivagem de C3b. As clivagens foram inibidas pela 1,10-fenantrolina, sugerindo a participação de metaloproteases. Metaloproteases de leptospira da família das termolisinas foram produzidas como proteínas recombinantes e clivaram C3 no SHN. Concluímos que proteases de leptospiras patogênicas podem desativar moléculas do complemento e são potencias alvos para novas terapias em leptospirose. / Leptospirosis is a zoonotic disease caused by pathogenic Leptospira. To establish the infection, these bacteria have developed strategies to escape the complement system. In this work, we demonstrate that culture supernatant from pathogenic Leptospira is capable of inhibiting the three complement pathways. We observe that this supernatant possess proteolytic activity under C3, C3b and iC3b, FB (alternative pathway), C2 and C4b (classical and lectin pathways). The proteins C3, C4, C2 and FB were also cleaved when normal human serum (NHS) was used as a source of complement. We demonstrate that these proteases act together with the host regulators Factor I and Factor H in C3b cleavage. The cleavages were inhibited by 1,10-phenanthroline, suggesting the involvement of metalloproteinases. Leptospira metalloproteinases from the thermolysin family were produced as recombinant proteins and cleaved C3 in NHS. We concluded that proteases from pathogenic Leptospira can inactivate complement molecules and are potential targets for new therapies in leptospirosis.
132

Evas?o no grupo discente do curso t?cnico em agropecu?ria do col?gio Dom Agostinho Ikas - Codai/UFRPE / Evasion in the student group of the technical course in agriculture in college Dom Augustine Ikas - Codai / UFRPE

Silva Sobrinho, Josias Limeira da 16 December 2015 (has links)
Submitted by Sandra Pereira (srpereira@ufrrj.br) on 2016-10-19T14:08:07Z No. of bitstreams: 1 2015 - Josias Limeira da Silva Sobrinho.pdf: 2492159 bytes, checksum: 96c586fd3cecc7f1bb9414ae01788024 (MD5) / Made available in DSpace on 2016-10-19T14:08:07Z (GMT). No. of bitstreams: 1 2015 - Josias Limeira da Silva Sobrinho.pdf: 2492159 bytes, checksum: 96c586fd3cecc7f1bb9414ae01788024 (MD5) Previous issue date: 2015-12-16 / The dropout problem as the Brazilian education has been extended to all levels of education, including technical courses in agronomy. The reasons are varied and consequential. Even if the settings of the courses of technical education institutions may suffer considerable changes, especially in provision of Law No. 11. 741 (2008). In this meaning, there is the importance of knowing the possible barriers traveled by students invested in this course and its dropouts them. Enabling new endowments in avoiding these outputs in order to search the interaction school community and technical student, stating that each member in their functions, have their responsibilities with this student body, their job prospects and even the contribution of the environment of pedagogical actions in Resolution of the problem avoidance. Postulating on the objectification of check truancy as a major challenge put to Codai in terms of access and permanence in Agricultural Technician course students, so that, to achieve this objectification leaned in targeted theoretical knowledge the topic and arranged in books, scientific articles, and electronic search, above all, support in the annotated in laws, decrees and resolutions that address the permeate of Brazilian education. Theoretical support that was the basis for general observations from the perspective of a documentary research on dropout cases occurring between 2010 and 2014, the technical agronomy course offered by the Agricultural College Dom Augustine Ikas - Codai / UFRPE. Located in the municipality of S?o Louren?o da Mata - PE. In addition to field research involving managers, teachers and alumni (escaped) this educational institution. So that the results may contribute to the existing research on the subject involved, but also be supportive knowledge of school life and the barriers faced as the causes of evasion, to take certifications as the school context and the challenges of young people are confronted in their professional preparation and factors such as economic issue; work and help the family; lack of motivation; the unsuitability for the course; lack of reconciliation between work and progress; Course expectations do not reach the expected, among others. Above all, the recognition that evasion back losses to the students, society and the public coffers / A evas?o como problem?tica do ensino brasileiro, vem se estendendo em todos os n?veis educacionais, inclusive em cursos t?cnicos em Agropecu?ria. Os motivos s?o variados e consequentes. Mesmo que as configura??es dos cursos das institui??es de Ensino T?cnico venham sofrer transforma??es consider?veis, em disposi??o principalmente da lei n? 11. 741 (2008). Nessa significa??o, verifica-se a import?ncia de se conhecer as poss?veis barreiras percorridas pelos alunos investidos nesse curso e suas desist?ncias dos mesmos. Possibilitando novas investiduras no evitar dessas sa?das com vista ? busca ? intera??o comunidade escolar e o estudante t?cnico, afirmando que cada membro, em suas fun??es, possui suas responsabilidades com esse alunado, suas perspectivas profissionais e at? mesmo a contribui??o da conjuntura de a??es pedag?gicas na resolu??o do problema evas?o. Postulando-se na objetiva??o de verificar a evas?o escolar como um dos grandes desafios posto ao Codai, em respeito ao acesso e perman?ncia de alunos do curso de T?cnico em Agropecu?ria, de forma que, para o alcance dessa objetiva??o debru?ou-se em conhecimentos te?ricos direcionados ao tema e dispostos em livros, artigos cient?ficos, e pesquisa eletr?nica, sobretudo, com apoio nos averbados em leis, decretos e resolu??es que contemplam o perpassar da educa??o brasileira. Suporte te?rico que foi a base para considera??es gerais sob a ?tica de uma pesquisa documental sobre casos de evas?o ocorridos entre os 2010 e 2014, no curso t?cnico de agropecu?ria oferecido pelo Col?gio Agr?cola Dom Agostinho Ikas ? Codai/ UFRPE. Situado no Munic?pio de s?o Louren?o da Mata ? PE. Somado-se a uma pesquisa de campo envolvendo gestor, professores e ex-alunos (evadidos) dessa institui??o de ensino. De forma que, os resultados obtidos venham contribuir com as pesquisas j? existentes quanto ? tem?tica envolvida, mas tamb?m ser suporte de conhecimentos da viv?ncia escolar e as barreiras enfrentadas como as causas da evas?o, no sentido de levar certifica??es quanto o contexto escolar e os desafios de jovens em defrontarem-se em sua prepara??o profissional e fatores como: quest?o econ?mica; trabalhar e ajudar a fam?lia; falta de motiva??o; a n?o adequa??o ao curso; falta de concilia??o entre trabalho e curso; expectativas do curso n?o alcan?am o esperado, entre outros. Sobretudo, o reconhecimento de que a evas?o tr?s preju?zos aos pr?prios alunos, a sociedade e aos cofres p?blicos
133

Reprova??o, abandono evas?o: um estudo de caso no curso de bacharelado em zootecnia da Universidade Tecnol?gica Federal do Paran? ? Campus Dois Vizinhos / Academic failure, Abandonment and Evasion: A case study at the Animal Science Course at Universidade Tecnologica Federal do Paran? - C?mpus Dois Vizinhos.

Piacentini, Claudia Cristina 25 September 2012 (has links)
Submitted by Celso Magalhaes (celsomagalhaes@ufrrj.br) on 2017-05-29T12:02:42Z No. of bitstreams: 1 2012 - Claudia Cristina Piacentini.pdf: 3027067 bytes, checksum: c656181a23ef0171a32290e3e283a819 (MD5) / Made available in DSpace on 2017-05-29T12:02:42Z (GMT). No. of bitstreams: 1 2012 - Claudia Cristina Piacentini.pdf: 3027067 bytes, checksum: c656181a23ef0171a32290e3e283a819 (MD5) Previous issue date: 2012-09-25 / This study addresses the issue of dropout students in higher education, which in turn arose from the unrest resulting from high dropout rates observed in Undergraduate courses at Universidade Tecnol?gica do Paran? ? C?mpus Dois Vizinhos, in this sense was delimited to approach specifically to the Course of Bachelor of Animal Science. The main objective sought to find factors that would contribute to promoting and improving education and retention of students in the Undergraduate Program in Animal Science UTFPR. In terms of theoretical frameworks, they understand concepts about academic evasion in national and international public policy and current higher education in Brazil. The survey used as technique in data collection primarily a survey of the numbers of evasion with the academic system of UTFPR and following questionnaires involving the students enrolled in Animal Science course, the evaded students and teachers who teach the course. The research is characterized as qualitative and quantitative, the method for data analysis was the content analysis. For the results it was identified that the possible causes of dropout are related to three perspectives: the early choice of profession that is linked to maturity and indecision; socioeconomic status of students that directly affects the permanence in the institution, and academic skills that are related to their school and little involvement with the course. From the identification of prospects it was suggested some programs that can assist in minimizing the dropout problem in Bachelor Degree in Animal Science from the University, thus promoting students to remain in the institution, the programs are: Mentoring Program; Grants to aid and needy students; Placement Program. As conclusion it is stated the challenge of seeking to introduce the programs at the University via Rectory so that they solidify and generate effective results / Este estudo aborda a tem?tica evas?o de alunos no ?mbito do ensino superior, que por sua vez surgiu da inquieta??o resultante dos elevados ?ndices de evas?o observados nos cursos de Gradua??o da Universidade Tecnol?gica Federal do Paran? ? C?mpus Dois Vizinhos, neste sentido, delimitou-se a abordagem especificamente ao Curso de Bacharelado em Zootecnia. O objetivo principal buscou encontrar elementos que viessem a contribuir e promover a melhoria do ensino e a perman?ncia dos discentes no Curso de Gradua??o em Zootecnia da UTFPR. Em termos de marcos te?ricos, estes compreenderam conceitos acerca da evas?o acad?mica em ?mbito nacional e internacional e as pol?ticas p?blicas atuais da educa??o superior no Brasil. A pesquisa utilizou como t?cnicas na coleta de dados primeiramente um levantamento dos n?meros da evas?o junto ao sistema acad?mico da UTFPR, e na sequ?ncia question?rios que envolveram os discentes regularmente matriculados no curso de zootecnia, os discentes evadidos e os docentes que ministram aulas no curso. A pesquisa caracteriza-se como qualitativa e quantitativa, sendo que o m?todo para a an?lise dos dados foi a an?lise de conte?do. Quanto aos resultados identificou-se que as poss?veis causas da evas?o est?o relacionadas a tr?s perspectivas: a escolha precoce da profiss?o que est? ligada ? maturidade e indecis?o; o n?vel socioecon?mico dos discentes que afeta diretamente na perman?ncia na Institui??o; e suas habilidades acad?micas que est?o relacionadas com sua trajet?ria escolar e ao pouco envolvimento com o curso. A partir da identifica??o das perspectivas, foram sugeridos alguns programas que podem auxiliar na minimiza??o da problem?tica evas?o no curso de bacharelado em zootecnia da Universidade, promovendo assim, a perman?ncia do aluno na Institui??o, os programas s?o: Programa de Tutoria; Bolsas de aux?lio aos discentes carentes e; Programa de Nivelamento. Como conclus?o fica o desafio de buscar introduzir os programas na Universidade via Reitoria, para que estes se solidifiquem e gerem resultados efetivos.
134

MINERAÇÃO DE DADOS APLICADA À CLASSIFICAÇÃO DOS CONTRIBUINTES DE ICMS DA SEFAZ-GO

Rocha, Santiago Meireles 18 August 2017 (has links)
Submitted by admin tede (tede@pucgoias.edu.br) on 2018-02-15T18:00:36Z No. of bitstreams: 1 SANTIAGO MEIRELES ROCHA.pdf: 972185 bytes, checksum: afac5e4d20639e20e3c5eed384124a70 (MD5) / Made available in DSpace on 2018-02-15T18:00:36Z (GMT). No. of bitstreams: 1 SANTIAGO MEIRELES ROCHA.pdf: 972185 bytes, checksum: afac5e4d20639e20e3c5eed384124a70 (MD5) Previous issue date: 2017-08-18 / With the exponential increase in the volume of data stored and the high potential for hidden knowledge in these data that can aid in the strategies and decision making of organizations, much has been invested in information technology and telecommunication. The purpose of this dissertation was to apply the Knowledge Discovery in Database (DCBD) process in order to classify the taxpayers of SEFAZ-GO ICMS in High Eviction and Low Eviction, through the task of data mining Supervised Classification, Implemented by the algorithm J48, on the WEKA computing platform. Three experiments were carried out with a sample of ICMS taxpayers data from the wholesale sector of the city of Goiânia-GO, with attributes selected from the Tax Code of the State of Goiás. During the experiments, the AttributeSelection and Discretize algorithms were applied. Reduction of attributes and transformation of the continuous variables into discrete ones, respectively. The statistical indices Confusion Matrix and Kappa Coefficient were used as validation metrics of the proposed model. After each experiment, classification rules were extracted, thus forming the proposed predictive model of classification. In the best scenario, a correct classification rate of 84% accuracy was obtained. Data mining is a reality within many organizations and can be a strong ally in fulfilling the, trivial, task of knowledge discovery in corporate databases. / Com o aumento exponencial do volume de dados armazenados e o alto potencial de conhecimento oculto nesses dados que pode auxiliar nas estratégias e nas tomadas de decisão das organizações, muito vem se investido em tecnologia da informação e telecomunicação. A presente dissertação teve como objetivo aplicar o processo de Descoberta do Conhecimento em Base de Dados (DCBD) a fim de classificar os contribuintes de ICMS da SEFAZ-GO em Alto Sonegador e Baixo Sonegador, por meio da tarefa de mineração de dados Classificação Supervisionada, implementada pelo algoritmo J48, na plataforma computacional WEKA. Foram realizados 3 experimentos com uma amostra de dados de contribuintes de ICMS do setor atacadista do município de Goiânia-GO, com atributos selecionados a partir do Código do Tributário do Estado de Goiás. Durante os experimentos foram aplicados os algoritmos AttributeSelection e Discretize, para a redução de atributos e transformação das variáveis contínuas em discretas, respectivamente. Os índices estatísticos Matriz de Confusão e Coeficiente de Kappa foram utilizados como métricas de validação do modelo proposto. Após cada experimento, regras de classificação foram extraídas formando assim o modelo preditivo proposto de classificação. Obteve-se, no melhor cenário, uma taxa de classificação correta de 84% de acerto. A mineração de dados é uma realidade dentro de muitas organizações e pode ser uma forte aliada no cumprimento da, nada trivial, tarefa de descoberta de conhecimento nas bases de dados corporativas.
135

AS CONDIÇÕES DE OFERTAS DOS CURSOS DE LICENCIATURA EM FÍSICA: O CASO DO INSTITUTO FEDERAL DE GOIÁS

Silva, Flávia Cristiane Pires e Silva 06 August 2018 (has links)
Submitted by admin tede (tede@pucgoias.edu.br) on 2018-10-09T19:02:34Z No. of bitstreams: 1 FLÁVIA CRISTIANE PIRES E SILVA.pdf: 1813866 bytes, checksum: db1b1c38e0970a68e7a34873107d6df6 (MD5) / Made available in DSpace on 2018-10-09T19:02:34Z (GMT). No. of bitstreams: 1 FLÁVIA CRISTIANE PIRES E SILVA.pdf: 1813866 bytes, checksum: db1b1c38e0970a68e7a34873107d6df6 (MD5) Previous issue date: 2018-08-06 / This work presents as the theme "The conditions of offer of the undergraduate course in physics: The case of the Federal Institute of Goiás" and aims to study the conditions of offers of the course of physics. It will be developed by qualitative research, being used to collect concrete data on the subject studied, to analyze and conclude methodologically the object of study. The research aims to obtain concrete data on the course, about when the course was founded, if there was market demand, how many classes have formed, how many students enter by semester and how many conclude the course to evasion and how is worked this evasion and repetition. What is the purpose of the course for training teachers or researchers? Back to bachelor or bachelor degree? Finally, the purpose of this research and to know the actual conditions of the course offered, to evaluate the joints between higher education in physics, technologies, teaching methodologies, teacher training, course laboratories. For the development of this work, we prioritized the Documentary Research in template base In semi interview -structured with the coordinator of the course of physics of the IFG, but also were made bibliographical research, using books, magazines, internet and institutional documents. This research has as its main theoretical-pedagogical reference the historical-cultural perspective and has as main author: Libâneo (2013). The research tool used was a closed questionnaire composed of questions that inquired about the actual conditions of the course offer. The result of the survey detected that the high rate of evasion and repetition due to several factors, more specific the misconceptions of the teachers of the course of physics. / Este trabalho apresenta como tema, “As condições de oferta do curso de licenciatura em Física: O caso do Instituto Federal de Goiás’’. Possui como objetivo, investigar alguns aspectos relevantes para a formação do professor de física, como a articulação entre a parte epistemológica e a parte didática, evasão e repetência. O trabalho foi desenvolvido mediante a pesquisa qualitativa, utilizada para coletar dados concretos sobre o tema estudado, para analisar e concluir metodologicamente o objeto de estudo. A pesquisa visou obter dados concretos sobre o curso e sobre a sua fundação, se ocorreu a procura de mercado, quantas turmas já formaram, quantos alunos entram por semestre e quantos concluem o curso, se existe a evasão e como é trabalhada essa evasão e repetência? Qual o objetivo do curso para a formação de professores ou pesquisadores? Voltado para bacharel ou licenciatura? O intuito da pesquisa foi conhecer as reais condições de oferta do curso, avaliar as articulações entre ensino superior em física, tecnologias, metodologias de ensino, formação de docentes e laboratórios do curso. Para o desenvolvimento deste trabalho, priorizou-se a pesquisa documental em campo, com base em entrevista semiestruturada com o coordenador do curso de física do IFG; além disto, foram produzidas pesquisas bibliográficas, utilizando-se de livros, revistas, internet e documentos institucionais. Esta pesquisa tem como sua principal referência teórica-pedagógica, a perspectiva histórico-cultural e com principal autor: Libâneo (2013). O instrumento de pesquisa utilizado foi um questionário fechado, composto por questões que indagavam sobre as reais condições da oferta do curso. O resultado da pesquisa, detectou que o alto índice de evasão e repetência é devido a vários fatores, especificamente às concepções equivocadas do docentes do curso de física; entre esses motivos, a investigação concluiu que, a articulação entre a parte epistemológica do conhecimento de física e da didática, não acontece no interior do curso, durante a formação do professor de física, o que irá refletir de forma circundante e enfática na monografia de final de curso. A pesquisa revelou que em todas as monografias de final de curso, nenhuma delas tratam de temas ligados ao ensino aprendizagem de física, mas sim a conhecimentos específicos de física.
136

Higher taxes, more evasion? Evidence from border differentials in TV license fees

Berger, Melissa, Fellner-Röhling, Gerlinde, Sausgruber, Rupert, Traxler, Christian 10 February 2016 (has links) (PDF)
This paper studies the evasion of TV license fees in Austria. We exploit border differentials to identify the effect of fees on evasion. Comparing municipalities at the low- and high-fee side of state borders reveals that higher fees trigger significantly more evasion. Our preferred estimator indicates that a one percent increase in fees raises the evasion rate by 0.3 percentage points. The positive effect of fees on evasion is confirmed in different parametric and non-parametric approaches and survives several robustness checks.
137

Three essays on tax compliance and the estimation of income-gaps

Gonzalez Cabral, Ana Cinta January 2017 (has links)
Quoting James Andreoni, `the problem of tax compliance is as old as taxes themselves'. The sources of missing tax revenues have traditionally concerned tax administrations and particularly now in times when public finances are striving. In the quest for analysing the revenue that is foregone, tax administrations have started to produce a report of their tax gap, understood as the difference between the theoretical tax liability and the actual collection, to obtain a measure of the extent of non-compliance. Due to the complexity of the non-compliance behaviour and the lack of visibility of certain types of income, different methods are usually put in place in order to offer a plausible range for the estimates. This dissertation dedicates its two first chapters to providing an alternative method for estimating the income-gap (de fined to be one minus the proportion of reported to actual income) for two populations: the self-employed and the employees. The underlying data used for both cases is publicly available survey data on expenditures and income that is generated on a timely manner. This carries substantial advantages. First, relying on a general purpose survey dataset means that the estimation can be updated more frequently than if it was to rely solely on either the timing of administrative data or on survey data that is speci fically targeted to measure non-compliance. Second, it provides an alternative estimation using an independent source of data which allows for the triangulation of the estimate obtained using administrative sources. Third, it allows tax administrations which do not have readily available administrative data to perform estimations using a type of survey widespread available in most countries. The third chapter of this thesis explores the role of the extrinsic and intrinsic incentives in explaining engagement in the hidden economy defined as undeclared work practices. This chapter contributes firstly to the literature on shadow economy and to the debate of whether crowding effects are found between extrinsic and intrinsic motivations in a tax environment.
138

Caracterização do fator de elongação Tu (EF-Tu) de Leptospira: aspectos relacionados à colonização e evasão ao sistema complemento do hospedeiro / Characterization of elongation factor Tu (EF-Tu) Leptospira: aspects related to colonization and evasion of the host complement system

Wolff, Danielly Gonçalves 14 August 2013 (has links)
A leptospirose é uma zoonose causada por bactérias patogênicas do gênero Leptospira. A doença representa um grave problema de saúde pública nos países tropicais subdesenvolvidos. Mais de 500.000 casos graves de leptospirose são notificados a cada ano e a taxa de mortalidade excede 10% (World Health Organization, 1999). Os roedores são o principal reservatório urbano da doença, e eliminam leptospiras viáveis no meio ambiente ao longo de toda a vida. As bactérias entram no hospedeiro por abrasões na pele ou por membranas mucosas e rapidamente se espalham pelo organismo atingindo vários órgãos. A identificação de mecanismos de invasão e de evasão imune apresentados por leptospiras patogênicas é extremamente relevante e tem sido alvo de pesquisas recentes desenvolvidas por vários grupos. Nesse contexto, a caracterização funcional de proteínas de membrana externa de Leptospira, principais alvos de interação com moléculas do hospedeiro, é de grande importância. O Fator de Elongação Tu (EF-Tu), uma proteína bacteriana abundante envolvida na síntese protéica, pertence à categoria das proteínas conhecidas como \"moonlighting\". Tais moléculas possuem a capacidade de exercer mais de uma função e, normalmente, localizam-se em diferentes compartimentos da célula. Há relatos de que EF-Tu de agentes patogênicos possa atuar como um fator de virulência. No presente trabalho, demonstrou-se que EF-Tu de Leptospira está localizado na superfície da bactéria e possui funções adicionais, sendo receptor para moléculas presentes no plasma do hospedeiro. Tal proteína interage com vários componentes da matriz extracellular e também com plasminogênio, de maneira dosedependente. Resíduos de lisina são importantes para essa interação. Plasminogênio ligado a EF-Tu é convertido em sua forma ativa, plasmina, que, por sua vez, é capaz de clivar os substratos naturais C3b e fibrinogênio. EF-Tu de Leptospira também se liga a Fator H, principal regulador da via alternativa do sistema complemento, e este mantém sua atividade funcional ao agir como co-fator de Fator I na clivagem de C3b. O potencial imunoprotetor de EF-Tu em modelo animal foi avaliado, tendo em vista o alto grau de conservação da proteína em diferentes espécies de Leptospira. EF-Tu não conferiu proteção significativa e, portanto, não deve ser considerado como um candidato vacinal contra a leptospirose. Em suma, EF-Tu de Leptospira deve contribuir para o processo de invasão e evasão ao sistema imune inato do hospedeiro, inativando o sistema complemento. Tanto quanto é do nosso conhecimento, essa é a primeira descrição de uma proteína \"moonlighting\" em Leptospira. / Leptospirosis is a zoonosis caused by pathogenic bacteria from the genus Leptospira. The disease represents a serious public health problem in underdeveloped tropical countries. More than 500,000 cases of severe leptospirosis are reported each year, with mortality rates exceeding 10% (World Health Organization, 1999). Rodents are the main urban reservoir of the disease, shedding viable leptospires throughout their lives in the environment. Leptospires infect hosts through small abrasions in the skin or mucous membranes and they rapidly disseminate to target organs. The identification of invasion mechanisms and immune evasion strategies employed by pathogenic leptospires is of great relevance. In this context, functional characterization of leptospiral outer membrane proteins, which represent the main targets for interaction with host molecules, is extremely important. The elongation factor Tu (EF-Tu), an abundant bacterial protein involved in protein synthesis, has been shown to display moonlighting activities. Known to perform more than one function at different times or in different places, it is found in several subcellular locations in a single organism, and may serve as a virulence factor in a range of important human pathogens. In this work we demonstrate that Leptospira EF-Tu is surface-exposed and performs additional roles as a cell-surface receptor for host plasma proteins. It interacts with several extracellular matrix components and also binds plasminogen in a dose-dependent manner. Lysine residues are critical for this interaction. Bound plasminogen is converted to active plasmin, which, in turn, is able to cleave the natural substrates C3b and fibrinogen. Leptospira EF-Tu also acquires Factor H (FH), the main soluble regulator of the alternative pathway of the complement system. FH bound to immobilized EF-Tu displays cofactor activity, mediating C3b degradation by Factor I (FI). Given the wide distribution of EF-Tu among Leptospira species, its immunoprotective potential was evaluated in an animal model. EF-Tu was not able to afford significant immunoprotection, and might not be considered a vaccine candidate against leptospirosis. In conclusion, EF-Tu may contribute to leptospiral tissue invasion and complement inactivation. To our knowledge, this is the first description of a leptospiral protein exhibiting moonlighting activities.
139

Identificação de proteases de Leptospira envolvidas com mecanismos de escape do sistema complemento humano. / Identification of leptospiral proteases involved in immune evasion mechanisms from the human complement system.

Fraga, Tatiana Rodrigues 01 August 2014 (has links)
A leptospirose é uma zoonose causada por leptospiras patogênicas. Para estabelecer a infecção, estas bactérias desenvolveram estratégias de escape ao sistema complemento. Neste trabalho demonstramos que o sobrenadante de cultura de leptospiras patogênicas é capaz de inibir as três vias do complemento. Observamos que esse sobrenadante possui atividade proteolítica sobre C3, C3b e iC3b, além do FB (via alternativa), C2 e C4b (via clássica e das lectinas). As proteínas C3, C4, C2 e FB também foram clivadas quando soro humano normal (SHN) foi utilizado como fonte de complemento. Demonstramos que as proteases atuam em conjunto com os reguladores do hospedeiro Fator I e Fator H na clivagem de C3b. As clivagens foram inibidas pela 1,10-fenantrolina, sugerindo a participação de metaloproteases. Metaloproteases de leptospira da família das termolisinas foram produzidas como proteínas recombinantes e clivaram C3 no SHN. Concluímos que proteases de leptospiras patogênicas podem desativar moléculas do complemento e são potencias alvos para novas terapias em leptospirose. / Leptospirosis is a zoonotic disease caused by pathogenic Leptospira. To establish the infection, these bacteria have developed strategies to escape the complement system. In this work, we demonstrate that culture supernatant from pathogenic Leptospira is capable of inhibiting the three complement pathways. We observe that this supernatant possess proteolytic activity under C3, C3b and iC3b, FB (alternative pathway), C2 and C4b (classical and lectin pathways). The proteins C3, C4, C2 and FB were also cleaved when normal human serum (NHS) was used as a source of complement. We demonstrate that these proteases act together with the host regulators Factor I and Factor H in C3b cleavage. The cleavages were inhibited by 1,10-phenanthroline, suggesting the involvement of metalloproteinases. Leptospira metalloproteinases from the thermolysin family were produced as recombinant proteins and cleaved C3 in NHS. We concluded that proteases from pathogenic Leptospira can inactivate complement molecules and are potential targets for new therapies in leptospirosis.
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The Relationship Between Austrian Tax Auditors and Self-Employed Taxpayers: Evidence From a Qualitative Study

Gangl, Katharina, Hartl, Barbara, Hofmann, Eva, Kirchler, Erich 05 1900 (has links) (PDF)
A constructive, highly professional relationship between tax authorities and taxpayers is essential for tax compliance. The aim of the present paper was to explore systematically the determinants of this relationship and related tax compliance behaviors based on the extended slippery slope framework. We used in-depth qualitative interviews with 33 self-employed taxpayers and 30 tax auditors. Interviewees described the relationship along the extended slippery slope framework concepts of power and trust. However, also novel sub-categories of power (e.g., setting deadlines) and trust (e.g., personal assistance) were mentioned. Furthermore, also little-studied categories of tax behavior emerged, such as accepting tax behavior, e.g., being available to the tax authorities, or stalling tax behavior, e.g., the intentional creation of complexity. The results comprehensively summarize the determinants of the tax relationship and tax compliance behaviors. Additionally, results highlight future research topics and provide insights for policy strategies.

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