Identification of the long polar fimbriae gene variants in the locus of enterocyte effacement-negative Shiga toxin-producing Escherichia coli strains isolated from humans and cattle in Argentina

The long polar fimbriae (Lpf) is one of few adhesive factors of Shiga toxin-producing Escherichia coli (STEC) and it is associated with colonization of the intestine. Studies have demonstrated the presence of lpf genes in several pathogenic E. coli strains, and classification of variants based on polymorphisms in the lpfA1 and lpfA2 genes has been adopted. Using a collection of Argentinean locus of enterocyte effacement (LEE)-negative STEC strains, we determined that the different lpfA types were present in a wide variety of serotypes with no apparent association between the types of lpfA1 or lpfA2 genes and the severity of human disease. The lpfA2-1 was the most prevalent variant identified, which was present in 95.8% of the isolates, and lpfA1-3 and lpfA2-2, proposed as specific biomarkers of E. coli O157:H7, were not found in any of the serotypes studied. The prevalence of lpf genes in a large number of strains is useful to understand the genetic diversity of LEE-negative STEC and to define the association of some of these isolates carrying specific lpf-variants with disease.Fil: Galli, Lucía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico CONICET- La Plata. Instituto de Genética Veterinaria "Ing. Fernando Noel Dulout". Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Instituto de Genética Veterinaria; Argentina. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; ArgentinaFil: Torres, Alfredo G.. University of Texas Medical Branch; Estados UnidosFil: Rivas, Marta. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”; Argentin

La gobernabilidad controamericana en los noventa. Consideraciones sobre las posibilidades democráticas en la postguerra

El ensayo discute las posibilidades de construir la vida democrática en sociedades que salen de la guerra y la violencia, con rencores, pobreza e intolerancia. Con las causas que la provocaron, agravadas ahora. Tal es la situación de Guatemala, El Salvador y Nicaragua, afectadas por una guerra civil en la década de los ochenta. Señala las condiciones para alcanzar la única gobernabilidad deseada, la democrática, basada en la legitimidad y la eficiencia de las cohortes gobernantes; se apoya en un concepto de sociedad civil que destaca el valor de la participación de los intereses privados, animados por un sentido social en sus múltiples formas, dispuestos a la vida pública y política. El ensayo termina con dos ejemplos de ingobernabilidad en Nicaragua y Guatemala.The article discusses the situation of Nicaragua, Guatemala and El Salvador once the internal or external wars in these countries are almost finished. Generalized political violence may be about to disappear but the social, economic and political conditions produce that stable democracy is still more a goal than a reality. According to the argument, transitions to democracy are not finished since governability will be hard to achieve. Efficiency and legitimacy are two basic challenges that Central American polities must achieve to talk about consolidated democracy

Central America: from the revolutionary left to the left of social democracy

El ensayo se refiere a la situación de las izquierdas en Centroamérica, en la época anterior a la guerra civil (1970/80) y el periodo posterior. En el primero, la izquierda marxista fue clandestina, ilegal y reducida en número. El desarrollo de los movimientos guerrilleros en Nicaragua, El Salvador y Guatemala movilizó importantes sectores populares, cuyo programa incluía demandas democráticas y sociales y vagas menciones por el socialismo. En el período posconflicto, las izquierdas armadas se incorporaron como partidos políticos públicos y legales. En El Salvador y Nicaragua constituyen partidos con fuerte respaldo electoral. Socialdemócratas solo hay en Costa Rica. Hoy día, la izquierda marxista experimenta una pérdida de identidad y se dividen entre los nostálgicos que aun creen en la revolución y los realistas que enfrentan el nuevo desafío: la incorporación a las luchas electorales

Centroamérica: el estado de las ciencias sociales.

Este artículo trata sobre los estados de las ciencias sociales en Centroamérica; por el cual el autor aborda temas como: El posmodernismo, crisis de la pérdida del sentido ortodoxo , El Marxismo, estudios sobre la democracia, revoluciones, estados fallidos y paralelos todos estos relacionados a países centroamericanos

Developing Allometric Equations for Teak Plantations Located in the Coastal Region of Ecuador from Terrestrial Laser Scanning Data

Traditional studies aimed at developing allometric models to estimate dry above-ground biomass (AGB) and other tree-level variables, such as tree stem commercial volume (TSCV) or tree stem volume (TSV), usually involves cutting down the trees. Although this method has low uncertainty, it is quite costly and inefficient since it requires a very time-consuming field work. In order to assist in data collection and processing, remote sensing is allowing the application of non-destructive sampling methods such as that based on terrestrial laser scanning (TLS). In this work, TLS-derived point clouds were used to digitally reconstruct the tree stem of a set of teak trees (Tectona grandis Linn. F.) from 58 circular reference plots of 18 m radius belonging to three different plantations located in the Coastal Region of Ecuador. After manually selecting the appropriate trees from the entire sample, semi-automatic data processing was performed to provide measurements of TSCV and TSV, together with estimates of AGB values at tree level. These observed values were used to develop allometric models, based on diameter at breast height (DBH), total tree height (h), or the metric DBH2 × h, by applying a robust regression method to remove likely outliers. Results showed that the developed allometric models performed reasonably well, especially those based on the metric DBH2 × h, providing low bias estimates and relative RMSE values of 21.60% and 16.41% for TSCV and TSV, respectively. Allometric models only based on tree height were derived from replacing DBH by h in the expression DBH2 x h, according to adjusted expressions depending on DBH classes (ranges of DBH). This finding can facilitate the obtaining of variables such as AGB (carbon stock) and commercial volume of wood over teak plantations in the Coastal Region of Ecuador from only knowing the tree height, constituting a promising method to address large-scale teak plantations monitoring from the canopy height models derived from digital aerial stereophotogrammetry

Multi-objective optimisation of bio-based thermal insulation materials in building envelopes considering condensation risk

The reduction in energy demand for heating and cooling with insulation materials increases the material related environmental impact. Thus, implementing low embodied energy materials may equilibrate this trade-off. Actual trends in passive house postulate bio-based materials as an alternative to conventional ones. Despite that, the implementation of those insulators should be carried out with a deeper analysis due to their hygroscopic properties. The moisture transfer, the associated condensation risk and the energy consumption for seven biobased materials and polyurethane for a building-like cubicle are analysed. The performance is evaluated combining a software application to model the cubicle (EnergyPlus) and a tool to optimize its performance (jEPlus). The novelty of this optimization approach is to include and evaluate the effects of moisture in these insulation materials, taking into account the mass transfer through the different layers and the evaporation of the different materials. This methodology helps optimise the insulation type and thickness verifying the condensation risk, preventing the deterioration of the materials. The total cost of the different solutions is quantified, and the environmental impact is determined using the life cycle assessment methodology. The effect of climate conditions and the envelope configuration, as well as the risk of condensation, are quantified. The results show that cost and environmental impact can be reduced if bio-based materials are used instead of conventional ones, especially in semiarid climates. Condensation risk occurs for large thicknesses and in humid climates. In our case studies, hemp offered the most balanced solution.The authors would like to acknowledge financial support from the Spanish Government (CTQ2016-77968-C3-1-P, ENE2015-64117-C5-1-R, ENE2015-64117-C5-3-R, MINECO/FEDER, UE). The research leading to these results has received funding from the European Commission Seventh Framework Programme under grant agreement no. PIRSES-GA-2013-610692 (INNOSTORAGE). This project has received funding the European Union's Horizon 2020 Research and Innovation Program under grant agreement No 657466 (INPATH-TES). This article has been possible with the support of the Ministerio de Economía y Competitividad (MINECO) and the Universitat Rovira i Virgili (URV) (FJCI-2016-28789). Authors would like to acknowledge the Brazilian Government for their support by the CNPq (National Council for Scientific and Technological Development). M.P. would like to thank the Brazilian Education Ministry for the financial support received under the PNPD/Capes fellowship. L.F.C. would like to thank the Catalan Government for the quality accreditation given to her research group GREA (2014 SGR 123)

Identification of the Long Polar Fimbriae gene variants in Locus of Enterocyte Effacement-negative Shiga toxin-producing Escherichia coli strains isolated from humans and cattle in Argentina

The long polar fimbriae (Lpf) is one of few adhesive factors of Shiga toxin-producing Escherichia coli (STEC) and it is associated with colonization of the intestine. Studies have demonstrated the presence of lpf genes in several pathogenic E. coli strains, and classification of variants based on polymorphisms in the lpfA1 and lpfA2 genes has been adopted. Using a collection of Argentinean locus of enterocyte effacement (LEE)-negative STEC strains, we determined that the different lpfA types were present in a wide variety of serotypes with no apparent association between the types of lpfA1 or lpfA2 genes and the severity of human disease. The lpfA2-1 was the most prevalent variant identified, which was present in 95.8% of the isolates, and lpfA1-3 and lpfA2-2, proposed as specific biomarkers of E. coli O157:H7, were not found in any of the serotypes studied. The prevalence of lpf genes in a large number of strains is useful to understand the genetic diversity of LEE-negative STEC and to define the association of some of these isolates carrying specific lpf-variants with disease.Instituto de Genética Veterinari

Identification of the Long Polar Fimbriae gene variants in Locus of Enterocyte Effacement-negative Shiga toxin-producing Escherichia coli strains isolated from humans and cattle in Argentina

The long polar fimbriae (Lpf) is one of few adhesive factors of Shiga toxin-producing Escherichia coli (STEC) and it is associated with colonization of the intestine. Studies have demonstrated the presence of lpf genes in several pathogenic E. coli strains, and classification of variants based on polymorphisms in the lpfA1 and lpfA2 genes has been adopted. Using a collection of Argentinean locus of enterocyte effacement (LEE)-negative STEC strains, we determined that the different lpfA types were present in a wide variety of serotypes with no apparent association between the types of lpfA1 or lpfA2 genes and the severity of human disease. The lpfA2-1 was the most prevalent variant identified, which was present in 95.8% of the isolates, and lpfA1-3 and lpfA2-2, proposed as specific biomarkers of E. coli O157:H7, were not found in any of the serotypes studied. The prevalence of lpf genes in a large number of strains is useful to understand the genetic diversity of LEE-negative STEC and to define the association of some of these isolates carrying specific lpf-variants with disease.Instituto de Genética Veterinari

The long polar fimbriae (lpf) operon and its flanking regions in bovine Escherichia coli O157:H43 and STEC O136:H12 strains

Long polar fimbriae (Lpf) are intestinal adhesins and important virulence factors of pathogenic Escherichia coli strains. We cloned and sequenced the lpf2-1 operon (lpf2ABCD) and its flanking regions of an intimin- and Shiga toxin-negative E. coli O157:H43 strain from bovine origin, and also sequenced the lpf2-1 operon of 6 additional atypical O157 bovine Escherichia coli strains of various serotypes Nucleotide sequence comparison of these lpf operons showed sequence conservation as they contain only four polymorphic nucleotide positions. Investigation of these O157 strains as well as 13 Escherichia coli Reference Collection (ECOR) strains carrying the lpf2-1 allele revealed high degree of sequence conservation in the lpf2 flanking regions. The lpf2-1 allele is also present in a bovine Shiga toxin-producing E. coli STEC O136:H12 strain and in vitro adherence assays revealed that the absence of lpf2-1 in this strain did not affect its host cell-binding properties. Our data indicate that lpf2 loci is highly conserved in E. coli isolates, but its role in adherence might be masked by other uncharacterized adhesins