1,721,146 research outputs found
ETEC colonisation factors disrupt the antigen presenting capacity of porcine intestinal dendritic cells
Full text linkEnterotoxigenic E. coli (ETEC) are not only a major cause of diarrhoea in travellers to and children in developing countries, but also cause neonatal and postweaning diarrhoea in piglets, leading to a reduced feed conversion and a higher mortality rate. As a consequence ETEC infections result in severe economic losses in the swine production industry. This intestinal pathogen displays colonisation factors or fimbriae on its surface enabling the microorganism to adhere to the intestinal epithelium (Fig. 1). In pig, F4 and F18 fimbriae are the most frequently associated with ETEC-induced diarrhoea1. As opposed to F4 fimbriae, oral immunisation with F18 fimbriae doesn’t protect piglets from a subsequent challenge infection2. F18 fimbriae bind glycosphingolipids in the apical membrane of enterocytes, but no transcytosis occurs, resulting in lower sunepithelial antigen concentrations as compared to F4 fimbriae, which bind the transcytotic receptor aminopeptidase N3,4. However, M-cell mediated transport of F18 fimbriae should still occur. Hence, besides a lower antigen concentration, these fimbriae could affect the function of intestinal antigen presenting cells. Here, we investigated the influence of purified F18 fimbriae on the antigen presentation capacity of small intestinal lamina propria dendritic cells (LPDCs)
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
A step forward in oral vaccine design : aminopeptidase N-targeted antibody formats as carriers for oral subunit vaccines in piglets
No full textStrain-specific enterotoxin secretion and impact of gut epithelial cells on porcine ETEC toxin secretion
No full textPorcine ETEC is an important cause of bacterial diarrheal illness and is regarded as a global health threat for farm animals. Neonatal diarrhea (ND) and post weaning diarrhea (PWD) caused by ETEC result in severe economic losses for the farming industry worldwide due to increased morbidity and mortality and reduced growth rates. Neonatal piglets can be protected by the transfer of maternal antibodies upon vaccination of the sow. However, upon weaning piglets become highly susceptible to ETEC as the passive immunity wanes at weaning. To protect newly weaned piglets against ETEC infections, an oral live bivalent vaccine, Coliprotec® F4/F18 (Elanco GmbH), has been marketed in the EU and other countries since 2017. However, it could not provide complete protection to piglets. Furthermore, the live vaccine has some limitations and associated risks. Therefore, further research into the development of vaccines or alternative strategies is needed. This requires a deeper understanding of the pathogenesis of ETEC and its interaction with its hosts at the molecular level
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Role of IL-17 in intestinal immunity against F4⁺ enterotoxigenic Escherichia coli infections in pigs
Full text linkAppropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
APN-targeted β-glucan microparticles for oral immunisation
Full text linkEnterotoxigenic Escherichia coli (ETEC) infections are a major cause of morbidity and mortality among both humans and pigs. Human ETEC strains affect mainly children and are also a source of traveler’s diarrhoea in regions where ETEC is endemic. Porcine ETEC cause diarrhoea in neonatal and newly weaned piglets.1-3 Pathogenicity of these bacteria is associated with fimbrial adhesins that mediate their colonisation to the microvilli of the intestinal epithelial cells in the small intestine. Porcine ETEC strains express five different fimbriae, namely the F4, F5, F6, F18 and F41 fimbriae, of which F18 and F4 fimbriae are most frequently associated with post-weaning disease in pigs.4 Once colonised, ETEC strains will secrete heat-labile enterotoxins (LT) or heat-stable enterotoxins (STa or STb). These enterotoxins will disrupt the water and electrolyte balance in the intestine which will cause severe watery diarrhoea.5
In neonatal and recently weaned piglets, ETEC infections results in severe economic losses due to growth retardation, increased drug use and elevated mortality.6 Most neonatal infections can be prevented by a passive lactogenic immunity obtained by vaccination of the sow. These maternal vaccines are mainly applied parenterally in the pregnant sow and contain inactivated ETEC bacteria with fimbriae or purified fimbriae with or without LT.7 However, this passive protection disappears at the moment of weaning.8 For the control of post-weaning diarrhoea (PWD), antibiotics are commonly used.9, 10 Besides their prophylactic usage, antibiotics were also applied for improving growth and production. The long term and extensive use of antibiotics has resulted in the development of antibiotic resistance. Therefore, since 1 January 2006 all commonly-used antimicrobial growth promoters have been banned in the EU member states. However, this caused a reduced performance and increased morbidity in post-weaning pigs and consequently, the development of alternative strategies is required.11
A wide variety of immunomodulating substances used as in-feed additives have been proposed to help post-weaning piglets to cope with feed transition and stress during this period.12, 13 The aim of these dietary substances is to help piglets develop an ‘appropriate’ innate and acquired immunity at the intestinal mucosal surface to support a microenvironment for protection against enteric infections, including ETEC.11 Among these substances, a variety of non-digestible carbohydrates are extensively studied, such as β-glucans.14 The beneficial effects of dietary β-glucans have already been demonstrated. Indeed, these polysaccharides display immunomodulatory effects upon oral administration and are also known to improve growth and general performance of the individual.15-20 Although numerous articles have tried to unravel these immunostimulatory effects, there is no consensus about their mechanism of action. Understanding β-glucan-mediated effects by elucidating the main β-glucan receptor and its signalling pathway in immune cells is important to use these powerful modulating properties in the protection of newly-weaned piglets against enteropathogens.
Another strategy to prevent ETEC infections in post-weaning piglets consist of inducing an active mucosal immune response by oral vaccination of piglets. Thereby, it would be interesting to use the immunostimulatory potential of β-glucans. Interestingly, β-glucan microparticles (GPs) were recently described as promising antigen vehicle systems with inherent adjuvant capacity owing to their β-glucans. Moreover, these particles are known for their high antigen encapsulation, efficiency and safety.21-32 Unfortunately, developing oral subunit vaccines has been challenging due to numerous potential obstacles, such as the hostile environment of the gastro-intestinal tract, oral tolerance and the epithelial barrier.33-37 Many approaches have been described to overcome these limitations, including enteric coating, encapsulation in immune-stimulating antigen delivery systems and targeting to endocytotic receptors, located at the apical surface of intestinal epithelial cells.38
Chapter one will provide background information about β-glucans, their receptor usage and signalling, while the second chapter is focused on oral vaccination strategies and the potential role of β-glucans as both mucosal adjuvants and antigen vehicle system. Different methods for targeting particles to endocytotic receptors are discussed in the second chapter as well
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