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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.
1

Are tritrophic interactions shaped by plant genotype? A field experiment.

Nordström, Ylva January 2013 (has links)
In recent years it has become apparent that when studying plant-herbivore interactions, it is important to also consider the multitrophic context, i.e. to what extent generalist and specialist enemies act as bodyguards for the plant. I have performed a field experiment with 25 genets, varying in plant defense levels, of meadowsweet (Filipendula ulmaria) and its herbivore, the chrysomelid beetle Galerucella tenella. Each genet was treated with four different density manipulations of G. tenella (5, 15, 30, and 60 larvae per genet). The experiment was set up on an archipelago island with natural levels of a specialist hymenopteran parasitoid Asecodes parviclava and generalist natural enemies. I set up the following hypotheses: 1) larval survival will be higher on less defended plants than on more defended plants, 2) the proportion of parasitoids will be higher on more defended plants, and 3) larval survival will increase with increasing larval densities. The most important findings of the experiment were an overall very low total survival of larvae (G. tenella pupae and A. parviclava mummies), a generally high parasitism by A. parviclava on more defended plants, and that two groups of generalist predators (hunting and web-forming spiders) were more frequent on less defended plants. My study suggests that herbivore survival may not be higher on less defended plants under situations with abundant occurrence of generalist predators, as they are able to trace high-quality foraging sites.
2

Förenliga motsatser? : En jämförande studie om aggregering och deliberation i två e-petitionssystem

Kristensson, Robin January 2013 (has links)
This essay sets out to compare political participation in two e-petition systems: The Malmö initiative in Malmö, Sweden, and Better Reykjavik in Reykjavik, Iceland. The main question of the essay concerns the aggregative and deliberative qualities of the Malmö initiative and Better Reykjavik, as well as the relationship between aggregation and deliberation. This main question is divided into four subqueries that lead the empirical analysis. These are: (1) Which similarities and differences in terms of design are there between the Malmö initiative and Better Reykjavik? (2) To what extent have these systems mobilized an aggregative political participation? (3) What similarities and differences are there concerning aspects of deliberation? and (4) What is the correlation between aggregation and deliberation like in the two e-petition systems? The method in use is a comparative cross-sectional study with a 'most similar research design'. The empirical material of the essay includes every petition published since the start of the systems in 2008, which makes it a total survey. The petitions are analyzed by way of quantitative content analysis. In addition, the essay includes a qualitative content analysis of the design of the e-petition systems. The empirical study shows that Better Reykjavik has engaged much greater political participation in both aggregative and deliberative matters than the Malmö initiative has. Most of the differences found concerning aggregation and deliberation can be explained with differences in the design of the e-petition systems. First, Better Reykjavik offers more opportunities for aggregative participation and deliberation than Malmö. Second, the likelihood of actually getting the petition read by local politicians is far greater in Reykjavik than in Malmö. Concerning the relationship between aggregation and deliberation, this study finds no signs of contradiction between the two. As this is not a zero-sum game, e-petition systems are considered to hold good potential for meeting Robert Goodins desire to unite aggregative and deliberative ideals under the slogan "First talk, then vote".
3

Aspectos da reprodução, crescimento e comportamento agregativo de Allopeas gracilis (Hutton, 1834) (Mollusca, Subulinidae)

Santos, Emily Oliveira 28 February 2013 (has links)
Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-05-12T19:51:19Z No. of bitstreams: 1 emilyoliveirasantos.pdf: 546435 bytes, checksum: 460c394a2cc33df8f4de37247b96761e (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-06-27T20:08:43Z (GMT) No. of bitstreams: 1 emilyoliveirasantos.pdf: 546435 bytes, checksum: 460c394a2cc33df8f4de37247b96761e (MD5) / Made available in DSpace on 2016-06-27T20:08:43Z (GMT). No. of bitstreams: 1 emilyoliveirasantos.pdf: 546435 bytes, checksum: 460c394a2cc33df8f4de37247b96761e (MD5) Previous issue date: 2013-02-28 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O objetivo do presente trabalho foi descrever a história de vida da espécie Allopeas gracilis, através da avaliação do crescimento e reprodução. Avaliou-se também a influência do isolamento sobre esses aspectos, o investimento reprodutivo, o comportamento de retenção de ovos no oviduto e o comportamento agregativo. Para tanto, foram realizados quatro experimentos. No primeiro experimento, que objetivou avaliar o crescimento e a reprodução de indivíduos mantidos pareados e isolados, realizou-se o acompanhamento do ciclo biológico de 60 moluscos, dos quais 30 foram mantidos aos pares e 30 foram mantidos em isolamento durante 120 dias. A. gracilis apresentou grande plasticidade na forma de alocação de energia entre crescimento e reprodução de acordo com a forma de criação, sendo a reprodução e o crescimento maior para os animais mantidos pareados. No segundo experimento, que teve como objetivo caracterizar o investimento reprodutivo da espécie acompanhou-se durante 180 dias 60 moluscos, dos quais 30 moluscos foram mantidos isolados e 30 moluscos foram mantidos pareados. Após o nascimento dos filhotes, os moluscos parentais e respectiva prole foram pesados para o cálculo do investimento reprodutivo. Na idade de 120 dias, os moluscos mantidos isolados tiveram um investimento reprodutivo maior do que os moluscos pareados, nas idades de 150 dias e 165 dias foram os moluscos mantidos pareados que apresentaram um maior investimento reprodutivo. Já na idade de 180 dias não houve diferença significativa entre os investimentos reprodutivos dos dois grupos. O terceiro experimento teve como objetivos caracterizar o comportamento de retenção de ovos no oviduto. Para tanto foram separados 60 moluscos recém-eclodidos em caixas individuais formando dois grupos experimentais de 30 moluscos cada e observados até a detecção da presença de filhotes no oviduto e constatação da maturidade sexual. Na primeira fase do experimento, um grupo foi mantido em condições favoráveis de umidade do substrato, enquanto o outro foi mantido em condições de dessecação. Foi verificada a frequência de liberação de filhotes pelos moluscos de ambos os grupos. Após um período de 40 dias, o substrato da caixa em que foi mantido o grupo submetido à dessecação foi novamente umedecido, por mais 20 dias, constituindo a segunda fase do experimento. Observou-se que o grupo mantido em condições desfavoráveis de umidade reproduziu menos do que o grupo mantido em condições favoráveis, mostrando que com a falta de umidade os moluscos retêm os ovos no oviduto. No quarto experimento, que teve como objetivo caracterizar o comportamento agregativo de A. gracilis, foram obtidos 150 moluscos, que foram distribuídos em 15 caixas plásticas. Em cada caixa foram colocados quatro discos plásticos identificados, em posição equidistante, os quais serviram de abrigos para os animais. Foram colocados 10 animais no centro de cada caixa. Após 24, 48, 72, 96, 120 e 168 horas foram observados o número de agregados formados, a posição dos agregados (sob qual disco), o número de indivíduos por agregado e o número de indivíduos isolados. Após 168 horas de experimento os indivíduos foram transferidos para outras caixas, contendo terra vegetal, três novos discos e o disco que continha o maior agregado após as 168 horas. Foi verificado, após 24 e 48 horas, o número de indivíduos sob o disco condicionado. Constatou-se que A. gracilis apresenta comportamento agregativo, assim como outras espécies de subulinídeos. Em todas as caixas utilizadas e em todos os intervalos de tempo ao longo das primeiras 168 horas e das 48 horas seguintes houve a formação de agregados. / The aim of this work was to describe the life history of the species Allopeas gracilis, through the assessment of growth and reproduction. We also evaluated the influence of isolation, the reproductive investment, the eggs retention behavior and aggregative behavior of A. gracilis. Therefore, four experiments were conducted. The first experiment aimed to evaluate the growth and reproduction of individuals kept in isolation or in pairs. A. gracilis showed great plasticity in the energy allocation between growth and reproduction, the egg production and growth rates being higher for paired animals. The second experiment aimed to evaluate the reproductive effort of A. gracilis. After the birth of the juveniles, the offspring and parental individuals were weighed to calculate the reproductive investment. At the age of 120 days, the snails kept isolated showed higher reproductive effort than paired snails. At the age of 180 days there was no significant difference between the two groups. The third experiment aimed to characterize the behavior of eggs retention. Sixty newly hatched snails were assigned to individual boxes. The molluscs were observed until the detection of embryos in the oviduct, which confirmed that the snails have attained sexual maturity. In the first phase of the experiment, one group was kept in a favorable moisture condition, while the other was maintained in a desiccation condition. At the second phase of the experiment, after a period of 40 days, the substrate of the boxes in which the snails subjected to desiccation were maintained has been moistened. It was observed that the group kept in unfavorable moisture condition produced fewer eggs than the group kept in a favorable condition, retaining these egg in the oviduct and releasing then when the terrário were moistened again. The fourth experiment aimed to characterize the aggregative behavior of A. gracilis. For this, 150 molluscs were distributed in 15 plastic boxes. In each box four labeled plastic disks were placed in equidistant positions. These disks have served as shelters for the snails. Ten snails were placed in the center of each box. After 24, 48, 72, 96, 120 and 168 hours the number of aggregates formed were observed, as well the position of the aggregates (in which disk) and the number of individuals per aggregate. After 168 hours of experiment the snails were transferred to boxes containing new substrate, three new disks and disk that contained the largest aggregate after 168 hours (conditioned disk). After 24 and 48 hours, the number of individuals in the conditioned disk was obserfved. It was found that A. gracilis exhibits aggregative behavior like other species of subulinids.
4

Electro-Optical Properties of Colloidal Semiconductor Nanocrystals Made by Means of Coalescence

Porotnikov, Dmitry 13 May 2022 (has links)
No description available.
5

Synthesizing the Experiences of Children and Youth With Disabilities and Special Needs in Inclusive Education Using Meta-Aggregation

Paul, Tithi January 2021 (has links)
It has been well established that inclusive education is important in order to achieve high-quality education for all. Recent literature reviews examining the experiences of educators, parents, and students without disabilities in inclusive educations show that most have a positive attitude towards inclusive education. However, there is an important gap in the literature surrounding inclusive education, namely the perspectives of children and youth with disabilities and special needs. The first manuscript is a qualitative evidence synthesis on the perspectives of children and youth with disabilities and special needs regarding their experiences in inclusive education. I utilised the meta-aggregative approach developed by Joanna Briggs Institute to select, critically appraise, and synthesise qualitative studies to generate an understanding of the children’s experiences in different areas pertaining to their schooling. I suggest recommendations to be considered by policy makers and professionals working in the education system to better support students with disabilities, educators, and families. The second manuscript presents a reflection on the experience of conducting a meta- aggregative review from my point of view as a novice researcher. I highlight the specific challenges encountered, decision-making process, and the specific lessons learned at each stage of the review process with aims to help guide reviewers taking on a meta-aggregation or other similar tasks. I used my meta-aggregative review presented in my first manuscript as an example, where applicable, to elucidate the processes and lessons learned. Specific strategies and recommendation are outlined in this thesis that can serve to better support the implementation of inclusive education. Additionally, I present recommendations for reviewers and organizations developing literature review methods to improve the field and quality of qualitative evidence synthesis. / Thesis / Master of Science (MSc) / Inclusive education refers to the concept that all students, including students with disabilities, attend their neighbourhood schools and have the chance to participate in programs and activities with their peers. Although inclusive education is believed to be beneficial for everyone, we do not know much about the students’ experiences in these schools. In this thesis, I studied the school experiences of elementary, middle, and high school students with disabilities and special needs. While completing this study, I faced several challenges and difficult decisions. So, I described some likely challenges to doing this type of study, my decision-making process, and the specific lessons I learned while completing my first study; we hope to help guide researchers taking on similar tasks. Findings from my thesis contributes to a better understanding of students’ experiences in school. They also highlight how teachers, families, and others can help and be better supported to improve the students’ school experience.
6

Propriedades adesivas a substratos abióticos e bióticos, invasão e indução de apoptose celular de Corynebacterium pseudodiphtheriticum / Adhesive properties to abiotic and biotic substrates, invasion and induction of apoptosis of Corynebacterium pseudodiphtheriticum

Monica Cristina de Souza 20 March 2013 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A ocorrência de fenótipos multirresistentes de Corynebacterium pseudodiphtheriticum e sua associação a infecções graves, com elevada mortalidade em pacientes imunocomprometidos, aliados ao escasso conhecimento da virulência e patogenia destas infecções, motivou esta pesquisa, que teve como objetivo investigar mecanismos de virulência e resistência microbiana deste agente entre pacientes de um hospital universitário brasileiro. Um total de 113 amostras de C. pseudodiphtheriticum identificadas por métodos bioquímicos convencionais e sistema API-Coryne isoladas de pacientes de diferentes grupos etários. Os micro-organismos eram, em sua maioria, relacionados a infecções no trato respiratório (27,45%), urinário (29,20%) e sitios intravenosos (18,60%) e cerca de 32,70% das amostras foram provenientes de pacientes com pelo menos uma das condições predisponentes: insuficiência renal; transplante renal, tuberculose em paciente HIV+, câncer, cirrose hepática, hemodiálise e uso de cateter. As amostras testadas revelaram-se multirresistentes sendo a maioria resistente à oxacilina, eritromicina e clindamicina. A adesão das cepas ao poliestireno e ao poliuretano indicou o envolvimento de hidrofobicidade da superfície celular na fase inicial da formação de biofilmes. O crescimento subsequente conduziu à formação de microcolônias, agregados bacterianos densos incorporados na matriz exopolimérica rodeada por espaços vazios, típica de biofilmes maduros. Adicionalmente, a interação do micro-organismo com fibrinogênio e fibronectina humana indica o envolvimento destes componentes séricos na formação de biofilme, sugerindo a participação de diferentes adesinas neste processo e a capacidade deste agente formar biofilme in vivo. A afinidade por esses componentes e a formação de biofilme podem contribuir para o estabelecimento e disseminação da infecção no hospedeiro. Adicionalmente, as cepas de C. pseudodiphtheriticum isoladas de pacientes com infecções localizadas (ATCC10700/Pharyngitis) e sistêmicas (HHC1507/Bacteremia) exibiram um padrão de aderência agregativa-like a células HEp-2, caracterizado por aglomerados de bactérias com aparência de um "empilhado de tijolos". Através do teste FAS e ensaios de interação na presença de inibidores de citoesqueleto, demonstramos o envolvimento da polimerização de actina na internalização das cepas testadas. A internalização bacteriana e rearranjo do citoesqueleto pareceu ser parcialmente desencadeado pela ativação da tirosina-quinase. Finalmente, C. pseudodiphtheriticum foi capaz de sobreviver no ambiente intracelular e embora não tenha demonstrado capacidade de replicar intracelularmente, células HEp-2 foram incapazes de eliminar o patógeno completamente no ambiente extracelular no período de 24 horas. Todas as cepas estudadas foram capazes de induzir apoptose em células epiteliais 24 horas pós-infecção evidenciada pelo aumento significativo no número de células mortas e pela ocorrência de alterações nucleares reveladas através dos métodos de coloração pelo azul Trypan, pelo DAPI e microscopia electrônica de transmissão. Alterações morfológicas incluindo a vacuolização, a fragmentação nuclear e a formação de corpos apoptóticos foram observadas neste período. A citometria de fluxo demonstrou ainda uma diminuição significativa no tamanho das células infectadas e a utilização de dupla marcação (iodeto de propídio / anexina V) permitiu a detecção da ocorrência de necrose e apoptose tardia. Em conclusão, o conhecimento de tais características contribuiu para a compreensão de mecanismos envolvidos no aumento da frequência de infecções graves com elevada mortalidade em pacientes no ambiente hospitalar, por C. pseudodiphtheriticum, um patógeno rotineiramente subestimado em países em desenvolvimento. / The occurrence of multiresistant phenotypes and associated with severe infections, with high mortality in immunocompromised hosts due to Corynebacterium pseudodiphtheriticum, allied to little known about virulence and pathogenesis these infections, led to present investigation. The investigation aims to examine the virulence mechanisms and resistance to antimicrobial agents of C. pseudodiphtheriticum among patients with bacterial infections at a Brazilian teaching hospital. A total of 113 C. pseudodiphtheriticum strains identified by conventional biochemical methods and API-Coryne System were recovered from patients from different age groups. Micro-organisms were mostly related to infections in the respiratory tracts (27.45%), urinary (29.20%) and intravenous sites (18.60%) and approximately 32.70% samples were obtained of patients presenting at least one of the pre-disposing conditions: end-stage renal disease; renal transplant; AIDS and Mycobacterium tuberculosis infection; cancer, hepatic cirrhosis; haemodialysis and catheter use. Antimicrobial susceptibility tests identified multiresistant phenotypes. Most strains were resistant to oxacillin, erythromycin and clindamycin. Adherence to polystyrene and polyurethane indicated the involvement of cell surface hydrophobicity in the initial stage of biofilm formation. Further growth led to the formation of dense bacterial aggregates embedded in the exopolymeric matrix surrounded by voids, typical of mature biofilms. Data also showed C. pseudodiphtheriticum recognizing human fibrinogen (Fbg) and fibronectin (Fn) and involvement of these sera components in biofilm formation in conditioning films. These findings suggest that biofilm formation may be associated with the expression of different adhesins. C. pseudodiphtheriticum may form biofilm in vivo possibly by an adherent biofilm mode of growth in vitro currently demonstrated on hydrophilic and hydrophobic abiotic surfaces. The affinity to Fbg and Fn and the biofilm-forming ability may contribute to the establishment and dissemination of infection caused by C. pseudodiphtheriticum. Additionally, C. pseudodiphtheriticum strains isolated from patients with localized (ATCC10700/Pharyngitis) and systemic (HHC1507/Bacteremia) infections exhibited an aggregative adherence-like pattern to HEp-2 cells characterized by clumps of bacteria with a stacked-brick appearance. The fluorescent actin staining test demonstrated that actin polymerization is involved in the internalization of the C. pseudodiphtheriticum strains. Bacterial internalization and cytoskeletal rearrangement seemed to be partially triggered by the activation of tyrosine kinase activity. Although C. pseudodiphtheriticum strains did not demonstrate an ability to replicate intracellularly, HEp-2 cells were unable to fully clear the pathogen within 24 hours. All samples were able to induce apoptosis in HEp-2 cells 24 h post-infection, evidenced by significant increase in the number of dead cells and nuclear alterations were observed by the Trypan blue assay, DAPI and transmission electron microscopy. Morphological changes in HEp-2 cells observed 24 h post-infection included vacuolization, nuclear fragmentation and the formation of apoptotic bodies. Flow cytometry revealed an significant decrease in cell size of infected HEp-2 cells. Furthermore, a double-staining assay using Propidium Iodide/Annexin V gave information about the numbers of vital vs. early apoptotic cells and late apoptotic or secondary necrotic cells. In conclusion, these characteristics may contribute to understanding of mechanisms involved on increase of severe infection, with high mortality in nosocomial enviroment patients by C. pseudodiphtheriticum, a pathogen usually overlooked in emerging countries.
7

Propriedades adesivas a substratos abióticos e bióticos, invasão e indução de apoptose celular de Corynebacterium pseudodiphtheriticum / Adhesive properties to abiotic and biotic substrates, invasion and induction of apoptosis of Corynebacterium pseudodiphtheriticum

Monica Cristina de Souza 20 March 2013 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A ocorrência de fenótipos multirresistentes de Corynebacterium pseudodiphtheriticum e sua associação a infecções graves, com elevada mortalidade em pacientes imunocomprometidos, aliados ao escasso conhecimento da virulência e patogenia destas infecções, motivou esta pesquisa, que teve como objetivo investigar mecanismos de virulência e resistência microbiana deste agente entre pacientes de um hospital universitário brasileiro. Um total de 113 amostras de C. pseudodiphtheriticum identificadas por métodos bioquímicos convencionais e sistema API-Coryne isoladas de pacientes de diferentes grupos etários. Os micro-organismos eram, em sua maioria, relacionados a infecções no trato respiratório (27,45%), urinário (29,20%) e sitios intravenosos (18,60%) e cerca de 32,70% das amostras foram provenientes de pacientes com pelo menos uma das condições predisponentes: insuficiência renal; transplante renal, tuberculose em paciente HIV+, câncer, cirrose hepática, hemodiálise e uso de cateter. As amostras testadas revelaram-se multirresistentes sendo a maioria resistente à oxacilina, eritromicina e clindamicina. A adesão das cepas ao poliestireno e ao poliuretano indicou o envolvimento de hidrofobicidade da superfície celular na fase inicial da formação de biofilmes. O crescimento subsequente conduziu à formação de microcolônias, agregados bacterianos densos incorporados na matriz exopolimérica rodeada por espaços vazios, típica de biofilmes maduros. Adicionalmente, a interação do micro-organismo com fibrinogênio e fibronectina humana indica o envolvimento destes componentes séricos na formação de biofilme, sugerindo a participação de diferentes adesinas neste processo e a capacidade deste agente formar biofilme in vivo. A afinidade por esses componentes e a formação de biofilme podem contribuir para o estabelecimento e disseminação da infecção no hospedeiro. Adicionalmente, as cepas de C. pseudodiphtheriticum isoladas de pacientes com infecções localizadas (ATCC10700/Pharyngitis) e sistêmicas (HHC1507/Bacteremia) exibiram um padrão de aderência agregativa-like a células HEp-2, caracterizado por aglomerados de bactérias com aparência de um "empilhado de tijolos". Através do teste FAS e ensaios de interação na presença de inibidores de citoesqueleto, demonstramos o envolvimento da polimerização de actina na internalização das cepas testadas. A internalização bacteriana e rearranjo do citoesqueleto pareceu ser parcialmente desencadeado pela ativação da tirosina-quinase. Finalmente, C. pseudodiphtheriticum foi capaz de sobreviver no ambiente intracelular e embora não tenha demonstrado capacidade de replicar intracelularmente, células HEp-2 foram incapazes de eliminar o patógeno completamente no ambiente extracelular no período de 24 horas. Todas as cepas estudadas foram capazes de induzir apoptose em células epiteliais 24 horas pós-infecção evidenciada pelo aumento significativo no número de células mortas e pela ocorrência de alterações nucleares reveladas através dos métodos de coloração pelo azul Trypan, pelo DAPI e microscopia electrônica de transmissão. Alterações morfológicas incluindo a vacuolização, a fragmentação nuclear e a formação de corpos apoptóticos foram observadas neste período. A citometria de fluxo demonstrou ainda uma diminuição significativa no tamanho das células infectadas e a utilização de dupla marcação (iodeto de propídio / anexina V) permitiu a detecção da ocorrência de necrose e apoptose tardia. Em conclusão, o conhecimento de tais características contribuiu para a compreensão de mecanismos envolvidos no aumento da frequência de infecções graves com elevada mortalidade em pacientes no ambiente hospitalar, por C. pseudodiphtheriticum, um patógeno rotineiramente subestimado em países em desenvolvimento. / The occurrence of multiresistant phenotypes and associated with severe infections, with high mortality in immunocompromised hosts due to Corynebacterium pseudodiphtheriticum, allied to little known about virulence and pathogenesis these infections, led to present investigation. The investigation aims to examine the virulence mechanisms and resistance to antimicrobial agents of C. pseudodiphtheriticum among patients with bacterial infections at a Brazilian teaching hospital. A total of 113 C. pseudodiphtheriticum strains identified by conventional biochemical methods and API-Coryne System were recovered from patients from different age groups. Micro-organisms were mostly related to infections in the respiratory tracts (27.45%), urinary (29.20%) and intravenous sites (18.60%) and approximately 32.70% samples were obtained of patients presenting at least one of the pre-disposing conditions: end-stage renal disease; renal transplant; AIDS and Mycobacterium tuberculosis infection; cancer, hepatic cirrhosis; haemodialysis and catheter use. Antimicrobial susceptibility tests identified multiresistant phenotypes. Most strains were resistant to oxacillin, erythromycin and clindamycin. Adherence to polystyrene and polyurethane indicated the involvement of cell surface hydrophobicity in the initial stage of biofilm formation. Further growth led to the formation of dense bacterial aggregates embedded in the exopolymeric matrix surrounded by voids, typical of mature biofilms. Data also showed C. pseudodiphtheriticum recognizing human fibrinogen (Fbg) and fibronectin (Fn) and involvement of these sera components in biofilm formation in conditioning films. These findings suggest that biofilm formation may be associated with the expression of different adhesins. C. pseudodiphtheriticum may form biofilm in vivo possibly by an adherent biofilm mode of growth in vitro currently demonstrated on hydrophilic and hydrophobic abiotic surfaces. The affinity to Fbg and Fn and the biofilm-forming ability may contribute to the establishment and dissemination of infection caused by C. pseudodiphtheriticum. Additionally, C. pseudodiphtheriticum strains isolated from patients with localized (ATCC10700/Pharyngitis) and systemic (HHC1507/Bacteremia) infections exhibited an aggregative adherence-like pattern to HEp-2 cells characterized by clumps of bacteria with a stacked-brick appearance. The fluorescent actin staining test demonstrated that actin polymerization is involved in the internalization of the C. pseudodiphtheriticum strains. Bacterial internalization and cytoskeletal rearrangement seemed to be partially triggered by the activation of tyrosine kinase activity. Although C. pseudodiphtheriticum strains did not demonstrate an ability to replicate intracellularly, HEp-2 cells were unable to fully clear the pathogen within 24 hours. All samples were able to induce apoptosis in HEp-2 cells 24 h post-infection, evidenced by significant increase in the number of dead cells and nuclear alterations were observed by the Trypan blue assay, DAPI and transmission electron microscopy. Morphological changes in HEp-2 cells observed 24 h post-infection included vacuolization, nuclear fragmentation and the formation of apoptotic bodies. Flow cytometry revealed an significant decrease in cell size of infected HEp-2 cells. Furthermore, a double-staining assay using Propidium Iodide/Annexin V gave information about the numbers of vital vs. early apoptotic cells and late apoptotic or secondary necrotic cells. In conclusion, these characteristics may contribute to understanding of mechanisms involved on increase of severe infection, with high mortality in nosocomial enviroment patients by C. pseudodiphtheriticum, a pathogen usually overlooked in emerging countries.
8

Análise do perfil de virulência e epidemiologia molecular de Escherichia coli enteroagregativa (EAEC) isoladas de casos esporádicos de diarreia no Brasil um estudo retrospectivo de 2010 a 2016 /

Dias, Regiane Chrysostomo Bitencort. January 2020 (has links)
Orientador: Rodrigo Tavanelli Hernandes / Resumo: A Escherichia coli enteroagregativa (EAEC) é um importante agente causador de diarreia aguda e persistente em crianças e adultos em todo o mundo. EAEC é definida como isolados de E. coli que produzem o padrão de aderência agregativa (AA) em células epiteliais (HeLa e/ou HEp-2) cultivadas in vitro. O patotipo EAEC pode ser dividido em típico e atípico com base na presença do gene aggR, que codifica um ativador transcricional, presente apenas no primeiro grupo. O objetivo deste estudo foi caracterizar uma coleção de isolados de EAEC obtidos de pacientes com diarreia durante um período de 7 anos de vigilância epidemiológica (2010-2016). Um total de 220 isolados de EAEC (194 típicas e 26 atípicas) foi classificado nos distintos grupos filogenéticos de E. coli, e caracterizados quanto aos sorotipos (O:H), padrão de aderência produzidos em células HeLa, sensibilidade aos antimicrobianos, e a presença de 25 genes responsáveis por codificarem fatores de virulência no patotipo EAEC. A maioria dos isolados de EAEC foi classificada nos grupos filogenéticos A (44,1%; 97/220) e B1 (21,4%; 47/220). Em relação ao padrão de aderência, observamos que 92,7% (204/220) produziram o padrão AA. Além disso, foram identificados nove isolados (4,1%; 9/220) que produziram a aderência em cadeia (CLA), dos quais seis produziram concomitantemente o padrão AA, além de isolados de EAEC que produzem um padrão de aderência indefinido (1,4%; 3/220) e isolados não aderentes (3,6%; 8/220). Foi identificado some... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Enteroaggregative Escherichia coli (EAEC) is an important agent that causes acute and persistent diarrhea in children and adults worldwide. EAEC is defined as E. coli isolates that produce the aggregative adherence pattern (AA) on epithelial cells (HeLa and/or HEp-2) cultured in vitro. The EAEC pathotype can be divided in typical and atypical based on the presence of the aggR gene, which encodes a transcriptional activator, in the former group. The aim of this study was to characterize a collection of EAEC isolates obtained from diarrheal patients over a 7-year period of surveillance (2010-2016). A total of 220 EAEC isolates (194 typical and 26 atypical) were evaluated regarding the phylogenetic classification, serotypes, adherence pattern produced on HeLa cells, susceptibility to antimicrobial drugs and the presence of 25 virulence factor-encoding genes. The majority of the EAEC isolates were assigned to phylogroups A (44.1%; 97/220) and B1 (21.4%; 47/220). Regarding the adherence pattern, was observed that 92.7% (204/220) produced AA. Moreover, we identified nine isolates (4.1%; 9/220) that produced the chain-like adherence (CLA), with six of them producing concomitantly the AA pattern, besides EAEC isolates producing an undefined adherence (1.4%; 3/220) and isolates non-adherent (3.6%; 8/220). Only 0.9% (2/220) of the EAEC isolates studied presented the multidrug resistance phenotype. The genes encoding for the major pilin subunit of all five previously described aggregati... (Complete abstract click electronic access below) / Doutor
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Rich and Ever Richer: Differential Returns Across Socio-Economic Groups

Ederer, Stefan, Mayerhofer, Maximilian, Rehm, Miriam 06 1900 (has links) (PDF)
This paper estimates rates of return across the gross wealth distribution in eight European countries. Like differential saving rates, differential rates of return matter for Post Keynesian theory, because they impact the income and wealth distribution and add an explosive element to growth models. We show that differential rates of return matter empirically by merging data on household balance sheets with long-run returns for individual asset categories. We find that (1) the composition of wealth differentiates between three socioeconomic groups: 30% are asset-poor, 65% are middle-class home owners, and the top 5% are business-owning capitalists; (2) rates of return rise across all groups; and (3) rates of return broadly follow a log-shaped function across the distribution, where inequality in the lower half of the distribution is higher than in the upper half. If socioeconomic groups are collapsed into the bottom 95% workers and top 5% capitalists, then rates of return are 5.6% for the former and 7.2% for the latter. / Series: Ecological Economic Papers
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Rich and Ever Richer: Differential Returns Across Socio-Economic Groups

Ederer, Stefan, Mayerhofer, Maximilian, Rehm, Miriam 06 1900 (has links) (PDF)
This paper estimates rates of return across the gross wealth distribution in eight European countries. Like differential saving rates, differential rates of return matter for Post Keynesian theory, because they impact the income and wealth distribution and add an explosive element to growth models. We show that differential rates of return matter empirically by merging data on household balance sheets with long-run returns for individual asset categories. We find that (1) the composition of wealth differentiates between three socioeconomic groups: 30% are asset-poor, 65% are middle-class home owners, and the top 5% are business-owning capitalists; (2) rates of return rise across all groups; and (3) rates of return broadly follow a log-shaped function across the distribution, where inequality in the lower half of the distribution is higher than in the upper half. If socioeconomic groups are collapsed into the bottom 95% workers and top 5% capitalists, then rates of return are 5.6% for the former and 7.2% for the latter. / Series: Ecological Economic Papers

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