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Search Results: 1 - 10 of 12939 matches for " Marcelo Gottschalk "
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Immune Receptors Involved in Streptococcus suis Recognition by Dendritic Cells
Marie-Pier Lecours, Mariela Segura, Nahuel Fittipaldi, Serge Rivest, Marcelo Gottschalk
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0044746
Abstract: Streptococcus suis is an important swine pathogen and an emerging zoonotic agent of septicemia and meningitis. Knowledge on host immune responses towards S. suis, and strategies used by this pathogen for subversion of these responses is scarce. The objective of this study was to identify the immune receptors involved in S. suis recognition by dendritic cells (DCs). Production of cytokines and expression of co-stimulatory molecules by DCs were shown to strongly rely on MyD88-dependent signaling pathways, suggesting that DCs recognize S. suis and become activated mostly through Toll-like receptor (TLR) signaling. Supporting this fact, TLR2?/? DCs were severely impaired in the release of several cytokines and the surface expression of CD86 and MHC-II. The release of IL-12p70 and CXC10, and the expression of CD40 were found to depend on signaling by both TLR2 and TLR9. The release of IL-23 and CXCL1 were partially dependent on NOD2. Finally, despite the fact that MyD88 signaling was crucial for DC activation and maturation, MyD88-dependent pathways were not implicated in S. suis internalization by DCs. This first study on receptors involved in DC activation by S. suis suggests a major involvement of MyD88 signaling pathways, mainly (but not exclusively) through TLR2. A multimodal recognition involving a combination of different receptors seems essential for DC effective response to S. suis.
Characterization of porcine dendritic cell response to Streptococcus suis
Marie-Pier Lecours, Mariela Segura, Claude Lachance, Tufaria Mussa, Charles Surprenant, Maria Montoya, Marcelo Gottschalk
Veterinary Research , 2011, DOI: 10.1186/1297-9716-42-72
Abstract: Streptococcus suis is a major swine pathogen associated mainly with meningitis, although other pathologies have also been described such as septicemia with sudden death, endocarditis, arthritis, and pneumonia [1]. Among 35 serotypes described, serotype 2 is considered the most virulent and the most frequently isolated from both diseased pigs and humans. Consequently, most studies on virulence factors and the pathogenesis of infection have been carried out with this serotype [2]. Until recently, S. suis disease in humans has been considered as rare and only affecting people working with pigs or pork by-products. However, with a rising incidence in humans over the last years, S. suis is now considered as an important emerging zoonotic agent, especially in Asian countries, where S. suis has recently been identified as the leading cause of adult meningitis in Vietnam, the second in Thailand, and the third in Hong Kong. In 2005, an important outbreak occurred in China and resulted in 200 human cases with a fatality rate near 20% [1]. In humans, S. suis is mainly responsible for meningitis, septicemia and streptococcal toxic shock-like syndrome [1,3,4].Despite the increasing number of studies, the pathogenesis of the S. suis infection is still not completely understood and, to date, attempts to control the infection are hampered by the lack of an effective vaccine. The mechanisms involved in the host innate and adaptive immune responses toward S. suis as well as those used by S. suis to subvert these responses are unknown. Several virulence factors have been proposed to be involved in the pathogenesis of S. suis infection [5]. Among them, the capsular polysaccharide, which confers to the bacteria antiphagocytic properties, has been demonstrated as a critical virulence factor [2,6,7] and its structure was recently described [8]. In fact, non-encapsulated mutants were shown to be avirulent in mice and pig models of infection [2]. Among several proteins and enzymes, a hemoly
Sorotipagem de amostras de Streptococcus suis isoladas de suínos em granjas dos Estados de S?o Paulo, Minas Gerais e Paraná
Pagnani, Keila J.R.;Castro, Antonio F. Pestana;Gottschalk, Marcelo;Silveira, Wanderley D.;Nakazato, Gerson;
Pesquisa Veterinária Brasileira , 2002, DOI: 10.1590/S0100-736X2002000100002
Abstract: streptococcus suis infection in swine is common in all countries where hog production is well developed. this infection has been associated with bronchopneumonia, meningitis, arthritis, pericarditis, myocarditis, endocarditis, fibrinous polyserositis, septicaemia, rhinitis, and abortion. streptococcus suis has also been described as a pathogen for ruminants and humans. in brazil there are several clinical evidences about the existence of s. suis disease in pigs affecting more than 50% of farms in states of s?o paulo, minas gerais and paraná. in the present research 51 strains of s. suis isolated from piggeries of the states of s?o paulo, minas gerais and paraná were collected from different pathologies such as septicaemia, meningitis, arthritis and pneumonia and been recovered either in pure culture or as the predominant organism from porcine tissues. culture of specimens was carried out on 5% bovine blood agar plates incubated at 37°c for 24 hr. for the biochemical identification the a-hemolytic colonies of all capsulated isolates were submitted to various conventional tests, such as hydrolysis of arginine, voges-proskauer test, and production of acid from various carbohydrates (inulin, salicin, trehalose, lactose, sucrose, sorbitol, mannitol and glycerol). the strains were also tested for their ability to grow in the presence of 6,5% nacl and for the amylase production. in addition strains were tested by api strep 20 to confirm the identification of s.suis. for capsular typing only capsulated strains were typed by co-agglutination test, using antisera raised in rabbits against all reference strains from serotypes 1 to 8. strains belonging to other serotypes were also typed. the co-agglutination was used for serotyping and the capsular reaction test was carried out for measuring the potency of the prepared antisera. from the total of 51 examined strains the following results were obtained, with regard to serotyping: 30 (58,8%) were serotype 2, 11 (21,6%) were serot
Sorotipagem de amostras de Streptococcus suis isoladas de suínos em granjas dos Estados de S o Paulo, Minas Gerais e Paraná
Pagnani Keila J.R.,Castro Antonio F. Pestana,Gottschalk Marcelo,Silveira Wanderley D.
Pesquisa Veterinária Brasileira , 2002,
Abstract: Infec es causadas por Streptococcus suis s o muito comuns em países onde a indústria de carne suína é desenvolvida. Estas infec es est o relacionadas a casos clínicos de broncopneumonia, meningite, artrite, pericardite, miocardite, endocardite, poliserosite fibrinosa, septicemia, rinite e aborto. Esta bactéria também foi descrita como patógeno de ruminantes e humanos. No Brasil há evidências clínicas da existência de processos infecciosos causados por S. suis afetando mais de 50% das granjas em Estados como S o Paulo, Minas Gerais e Paraná. No presente estudo foram isoladas 51 amostras de S. suis de granjas do Estados acima referidos, coletadas de diferentes casos clínicos como septicemia, meningite, artrite e pneumonia, tendo sido obtidas ou em cultura pura ou como patógeno de maior predominancia nos tecidos de suínos. Este material foi semeado em Columbia ágar sangue adicionado de 5% de sangue bovino e incubado a 37°C por 24 horas. Para a identifica o bioquímica as col nias que apresentavam a-hemólise, bem como as amostras padr o, foram submetidas a testes convencionais para a confirma o da espécie S. suis, tais como: hidrólise de arginina, teste de Voges-Proskauer, e produ o de ácido a partir de vários carboidratos (inulina, salicina, trealose, lactose, sacarose, sorbitol, manitol e glicerol). As amostras também foram testadas para habilidade de crescimento em meio de TSA com 6,5% de NaCl e para a produ o de amilase. Todas as amostras que fizeram parte desta pesquisa foram testadas pelo sistema Api 20 Strep para confirma o dos resultados obtidos nos testes convencionais. Para a sorotipagem foram produzidos antissoros de 1 a 8. Outras amostras n o pertencentes a estes sorotipos também foram sorotipadas. O antissoro produzido em coelhos foi titulado pelo teste de aglutina o em tubo com 2-mercaptoetanol e pelo teste de rea o capsular e, quando adequados, foram usados no teste de co-aglutina o, para a sorotipagem das amostras de S. suis. A sorotipagem das 51 amostras isoladas mostraram os seguintes resultados: 30 (58,8%) foram classificadas como sorotipo 2, 11 (21,6%) das amostras como sorotipo 3, sete (13,72%) como sorotipo 7, duas (3,92%) como sorotipo 1 e uma amostra como pertencente ao sorotipo14 (1,96%). Este é o primeiro relato do isolamento de um grande número de amostras de S. suis no Brasil, de casos típicos de processos infecciosos causados por esta bactéria. Também foi realizada a sorotipagem dos isolados, mostrando uma alta prevalência do sorotipo 2, quando comparada com a dos demais sorotipos encontrados.
Evaluación de la virulencia y serotipos de Streptococcus suis aislados de trabajadores de rastros en el valle de Toluca, Estado de México, México
Martín Talavera Rojas,Marcelo Gottschalk,Valente Velázquez Ordó?ez
Veterinaria México , 2001,
Abstract: El propósito de este estudio fue aislar y determinar la virulencia y serotipos involucrados de Streptococcus suis en trabajadores con diferentes niveles de riesgo en cuatro rastros municipales (Mexicaltzingo, Ocoyoacac, Toluca y San Pablo Autopan) ubicados en el valle de Toluca, Estado de México, México. El muestreo se realizó al 100% de los trabajadores en cada rastro ubicados en el área de cerdos, dando un total de n = 69, a estos últimos se les tomaron hisopos de amígdalas para el aislamiento e identificación bacteriológica de Streptococcus suis, mediante procedimientos bioquímicos de bacteriología; la evaluación de la virulencia se realizó utilizando un modelo murino y la serotipificación mediante la técnica de coaglutinación. La evaluación de los resultados se analizó con estadística no paramétrica (Ji-cuadrada) con una significancia de P < 0.05. Se obtuvieron cuatro (5.7%) aislamientos de Streptococcus suis, encontrando una cepa por cada rastro estudiado. Las cepas fueron clasificadas como mediana y altamente virulentas, dando una mortalidad de 45% a 80%. Los serotipos encontrados fueron el 2 y 27, mientras que en dos cepas no se identificó ningún serotipo. La virulencia de las cepas aisladas de humanos en estos rastros fue mayor que las utilizadas como referencia. En el caso de la cepa serotipo 27, este es el primer informe en el ámbito mundial de este serotipo que se presenta en humanos, además de que las dos cepas donde no se identificó el serotipo pueden tratarse de serotipos nuevos.
Toll-Like Receptor 2-Independent Host Innate Immune Response against an Epidemic Strain of Streptococcus suis That Causes a Toxic Shock-Like Syndrome in Humans
Claude Lachance, Mariela Segura, Pehuén Pereyra Gerber, Jianguo Xu, Marcelo Gottschalk
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0065031
Abstract: Streptococcus suis is an emerging zoonotic agent causing meningitis and septicemia. Outbreaks in humans in China with atypical cases of streptococcal toxic shock-like syndrome have been described to be caused by a clonal epidemic S. suis strain characterized as sequence type (ST) 7 by multilocus sequence typing, different from the classical ST1 usually isolated in Europe. Previous in vitro studies showed that Toll-like receptor (TLR) 2 plays a major role in S. suis ST1 interactions with host cells. In the present study, the in vivo role of TLR2 in systemic infections caused by S. suis ST1 or ST7 strains using TLR2 deficient (TLR2?/?) mice was evaluated. TLR2-mediated recognition significantly contributes to the acute disease caused by the highly virulent S. suis ST1 strain, since the TLR2?/? mice remained unaffected when compared to wild type (WT) mice. The lack of mortality could not be associated with a lower bacterial burden; however, a significant decrease in the induction of pro-inflammatory mediators, as evaluated by microarray, real-time PCR and protein assays, was observed. On the other hand, TLR2?/? mice infected with the epidemic ST7 strain presented no significant differences regarding survival and expression of pro-inflammatory mediators when compared to the WT mice. Together, these results show a TLR2-independent host innate immune response to S. suis that depends on the strain.
Development of Multiplex PCR Assays for the Identification of the 33 Serotypes of Streptococcus suis
Zhijie Liu, Han Zheng, Marcelo Gottschalk, Xuemei Bai, Ruiting Lan, Shaobo Ji, Haican Liu, Jianguo Xu
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0072070
Abstract: Streptococcus suis is an important zoonotic agent causing severe diseases in pigs and humans. To date, 33 serotypes of S. suis have been identified based on antigenic differences in the capsular polysaccharide. The capsular polysaccharide synthesis (cps) locus encodes proteins/enzymes that are responsible for capsular production and variation in the capsule structures are the basis of S. suis serotyping. Multiplex and/or simplex PCR assays have been developed for 15 serotypes based on serotype-specific genes in the cps gene cluster. In this study, we developed a set of multiplex PCR (mPCR) assays to identify the 33 currently known S. suis serotypes. To identify serotype-specific genes for mPCR, the entire genomes of reference strains for the 33 serotypes were sequenced using whole genome high-throughput sequencing, and the cps gene clusters from these strains were identified and compared. We developed a set of 4 mPCR assays based on the polysaccharide polymerase gene wzy, one of the serotype-specific genes. The assays can identify all serotypes except for two pairs of serotypes: 1 and 14, and 2 and 1/2, which have no serotype-specific genes between them. The first assay identifies 12 serotypes (serotypes 1 to 10, 1/2, and 14) that are the most frequently isolated from diseased pigs and patients; the second identifies 10 serotypes (serotypes 11 to 21 except 14); the third identifies the remaining 11 serotypes (serotypes 22 to 31, and 33); and the fourth identifies a new cps cluster of S. suis discovered in this study in 16 isolates that agglutinated with antisera for serotypes 29 and 21. The multiplex PCR assays developed in this study provide a rapid and specific method for molecular serotyping of S. suis.
Triage — A South African perspective
S Gottschalk
Continuing Medical Education , 2004,
Internet filters in public libraries: do they belong?
Gottschalk, Lana
Library Student Journal , 2006,
Abstract: With the Children's Internet Protection Act (CIPA) of 2000, hundreds of public and school libraries in the United States have implemented internet filters. While filtering can keep children from viewing inappropriate Internet materials, the use of filters in public libraries infringes on the intellectual freedom of library users. Over-blocking and under-blocking are negatively affecting open research and use of online resources, bringing about profession-wide discussions about emerging technological changes in libraries. This essay examines these discussions and advocates for an approach incorporating privacy screens or recessed monitors, the establishment of clear Internet use policies, and better user education to help maintain the role of libraries as valued centers for free self-education and learning.
A Dark Side of Computing and Information Sciences: Characteristics of Online Groomers
Petter Gottschalk
Journal of Emerging Trends in Computing and Information Sciences , 2011,
Abstract: The European Online Grooming Project from 2009 to 2011 involved researchers from Norway, Italy, Belgium and the UK. The project had three separate but interlinked phases. The first was a scooping project. The second and third phases involved interviews with convicted online groomers across Europe and dissemination activity respectively. The key features of grooming behavior the study identified do not apply to all groomers in all contacts they have with young people. These features of online grooming include factors that help maintain the behavior such as the online environment, dissonance and offenders perceptions of young people and their behavior. The research also identified salient behaviors in the grooming process such as: scanning the online environment for potential people to contact, the identity adopted by the groomer (be it their own or another); the nature of contact with the young person; the different ways in which the online groomer can intensify the process of grooming and the diverse range of outcomes toward the end of the process. In particular, it is clear from the research that not all episodes of online grooming result in a physical meeting. The first ‘type’ of groomer identified is the distorted attachment offender. Men in this group had offence supportive beliefs that involved seeing contact with the young person as a ‘relationship’. The second type is the adaptable online groomer. This group of men had offence supportive beliefs that involved their own needs and seeing the victim as mature and capable. Finally, the hyper-sexualized group of men was characterized by extensive indecent image collections of children and significant online contact with other sexual offenders or offender groups.
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