1,362,516 research outputs found
Neisseria meningitidis differentially controls host cell motility through PilC1 and PilC2 components of type IV pili
No full textNeisseria meningitidis is a strictly human pathogen that has two facets since asymptomatic carriage can unpredictably turn into fulminant forms of infection. Meningococcal pathogenesis relies on the ability of the bacteria to break host epithelial or endothelial cellular barriers. Highly restrictive, yet poorly understood, mechanisms allow meningococcal adhesion to cells of only human origin. Adhesion of encapsulated and virulent meningococci to human cells relies on the expression of bacterial type four pili (T4P) that trigger intense host cell signalling. Among the components of the meningococcal T4P, the concomitantly expressed PilC1 and PilC2 proteins regulate pili exposure at the bacterial surface, and until now, PilC1 was believed to be specifically responsible for T4P-mediated meningococcal adhesion to human cells. Contrary to previous reports, we show that, like PilC1, the meningococcal PilC2 component is capable of mediating adhesion to human ME180 epithelial cells, with cortical plaque formation and F-actin condensation. However, PilC1 and PilC2 promote different effects on infected cells. Cellular tracking analysis revealed that PilC1-expressing meningococci caused a severe reduction in the motility of infected cells, which was not the case when cells were infected with PilC2-expressing strains. The amount of both total and phosphorylated forms of EGFR was dramatically reduced in cells upon PilC1-mediated infection. In contrast, PilC2-mediated infection did not notably affect the EGFR pathway, and these specificities were shared among unrelated meningococcal strains. These results suggest that meningococci have evolved a highly discriminative tool for differential adhesion in specific microenvironments where different cell types are present. Moreover, the fine-tuning of cellular control through the combined action of two concomitantly expressed, but distinctly regulated, T4P-associated variants of the same molecule (i.e. PilC1 and PilC2) brings a new model to light for the analysis of the interplay between pathogenic bacteria and human host cells
BIM PROCESS, ONTOLOGIES AND INTERCHANGE PLATFORM FOR CULTURAL ARCHITECTURAL HERITAGE MANAGEMENT: STATE OF ART AND DEVELOPMENT PERSPECTIVES
No full textOntology meaning and its declination in computer science are defined in the contribution. Some experiences of using ontologies for Cultural Heritage frame the state of the art. Specific ontologies for the conservation process allows the definition of classes and their description through attributes. Subjects, means, tools, relationships, and planning of activities, times and costs are included in the process. Ontologies so defined are also the basis for the definition of an interoperability protocol for Cultural Heritage. Interoperability means exchange among the tools, with the guarantee that data and meanings transmitted are correctly interpreted by the receiving system. The paper proposes the kind of informative model for built heritage. Defining the basis for ontologies is the goal. The flow of information in a Common Data Environment, a data exchange platform, is necessary to ensure proper data and process management
Fale Pili: a Tuvaluan perspective on mobility justice
No full textThis paper suggests that the Indigenous Tuvaluan concept of fale pili, looking after one’s neighbour as if they were family, must be centralised in understandings of mobility justice for Tuvaluan people. While the risks of sea level rise to Tuvalu’s low-lying national territory are well-recognised, the culturally specific ways in which Tuvaluans perceive and experience mobility are not. From a fale pili perspective, mobility is a way of enacting family, fenua (indigenous island within Tuvalu) and responsibilities to the Tuvaluan (political) community. Conceived in this way, Tuvaluan mobility does not primarily see migrant-as-individual; rather the migrant is always a representative of, and contributor towards, collective wellbeing of family, fenua and nation. Our paper is structured as follows. First, we discuss the importance of approaching both mobility and mobility justice as culturally specific concepts that are scripted and experienced by different peoples in different ways. To do so, we read contemporary theorisations of mobility (in)justice, and encourage attention to understanding the cosmological dimensions of contemporary (global) life that a critical civilisational perspective affords. Drawing on two case-studies of fale pili, one involving urban-rural migration in Tuvalu during the COVID-19 pandemic, and one involving Tuvaluan guest workers in Australia, we suggest that fale pili offers an approach to understanding mobility justice as culturally and geographically situated. By way of conclusion, we also consider the ways that fale pili can contribute to wider debates on mobility (in)justice in turbulent times.Full Tex
Crystal structure of the P pilus rod subunit PapA
No full textP pili are important adhesive fibres involved in kidney infection by uropathogenic Escherichia coli strains. P pili are assembled by the conserved chaperone-usher pathway, which involves the PapD chaperone and the PapC usher. During pilus assembly, subunits are incorporated into the growing fiber via the donor-strand exchange (DSE) mechanism, whereby the chaperone's G(1) beta-strand that complements the incomplete immunoglobulin-fold of each subunit is displaced by the N-terminal extension (Nte) of an incoming subunit. P pili comprise a helical rod, a tip fibrillum, and an adhesin at the distal end. PapA is the rod subunit and is assembled into a superhelical right-handed structure. Here, we have solved the structure of a ternary complex of PapD bound to PapA through donor-strand complementation, itself bound to another PapA subunit through DSE. This structure provides insight into the structural basis of the DSE reaction involving this important pilus subunit. Using gel filtration chromatography and electron microscopy on a number of PapA Nte mutants, we establish that PapA differs in its mode of assembly compared with other Pap subunits, involving a much larger Nte that encompasses not only the DSE region of the Nte but also the region N-terminal to it
Experimentation of a smart-planning approach for the sustainable renewal of the building heritage of smaller sardinian historic centers
No full textThe contribution discusses the results of an experiment on smart-planning approach configured as a territorial observatory. The definition of a methodological approach for an observatory for sustainable regeneration of the building heritage of Sardinian Historical Centers (HC) is the main target of the research work. The observatory aims to support the Local Administrations (LA), mainly of the small communities characterized by a lack of resources, in designing, assessing and monitoring policies and actions, providing a tool to build shared knowledge for stakeholders. The general framework of the observatory is consistent with the drawing process of the Detailed Plans of the Historic Centers—DPHC—(Piani Particolareggiati del Centro Storico—PPCS). It is configured as a multi-customer Web-GIS portal that encompasses a set of multidisciplinary indicators based on Open GeoData and baseline DPHC knowledge, combined with the Voluntary Geographic Information (VGI) derived from the feedback of the portal users. Thanks to recent funding for the DPHC, some extraordinarily detailed studies on the historical building heritage are now available, characterized by a certain uniformity that can be an excellent baseline data to identify a shared set of indicators. The definition of a dynamic, multidisciplinary and multi-scalar set of indicators is one of the key issues of the research work. Such set should be consistent with the local development strategies and with the specific regulatory context. The set of indicators outlines a “BASE Scenario” that could be adopted for the monitoring of the effectiveness of the plan and for the creation and assessment of several scenarios. The spatial structure of the indicators is formulated to embrace several levels of detail: aggregated indicators could be used for HC benchmarking and more detailed indicators could be a useful resource for designing scenarios and monitoring the plan. After a short presentation of the observatory framework, the paper focuses on the indicators and methodologies adopted for the energy efficiency and use of the building heritage. The energy-efficiency indicators are mainly calculated by a GIS procedure that is capable of performing Standard calculations (UNI 11300: 2014) for each building using the DPHC baseline data. The indicators about the use of the building are a synthesis of the results of a questionnaire survey addressed to the inhabitants of the historic centers. Finally, the paper reports the results of an experiment carried out on a Sardinian center. The experiment identifies some critical points and potentialities about the adopted energy-efficiency indicators and about the observatory’s general framework that will be the base for further developments
Functional characterization of a mucus-specific LPXTG surface adhesin from probiotic Lactobacillus rhamnosus GG
No full textIn spite of the wealth of clinical evidence supporting the health benefits of Lactobacillus rhamnosus GG in humans, there is still a lack of understanding of the molecular mechanisms behind its probiosis. Current knowledge suggests that the health-promoting effects of this probiotic strain might be partly dependent on its persistence in the intestine and adhesion to mucosal surfaces. Moreover, L. rhamnosus GG contains mucus-binding pili that might also explain the occupation of its ecological niche as a comparatively less stringent allochthonous intestine-dwelling bacterium. To uncover additional surface proteins involved in mucosal adhesion, we investigated the adherence properties of the only predicted protein (LGG_02337) in L. rhamnosus GG that exhibits homology with a known mucus-binding domain. We cloned a recombinant form of the gene for this putative mucus adhesin and established that the purified protein readily adheres to human intestinal mucus. We also showed that this mucus adhesin is visibly distributed throughout the cell surface and participates in the adhesive interaction between L. rhamnosus GG and mucus, although less prominently than the mucus-binding pili in this strain. Based on primary structural comparisons, we concluded that the current annotation of the LGG_02337 protein likely does not accurately reflect its predicted properties, and we propose that this mucus-specific adhesin be called the mucus-binding factor (MBF). Finally, we interpret our results to mean that L. rhamnosus GG MBF, as an active mucus-specific surface adhesin with a presumed ancillary involvement in pilus-mediated mucosal adhesion, plays a part in the adherent mechanisms during intestinal colonization by this probioti
Defining a methodology to integrate energy savings and renewal processes in the urban planning: a case study in the italian context
No full textThe design of urban sustainable regeneration actions and programs, which combines Renewal Energy System (RES) productions and new technologies for energy saving within the bonds and the resources of urban complex systems, is the key to reach the 20-20-20 target for our cities rather than our nations.
Improving the efficiency of residential building stock is the main target of the urban regeneration process, unfortunately the definition of buildings energy demand and its representation at the urban level raise some problems due to the lack of available base data and to the strong variability of the factors that affect it.
Therefore, architectural and urban planning needs tools and methodologies able to define, asses and represent hypothetical scenarios both on production of energy with RES as well as on results of building energy efficiency improvements at the urban scale. These tools must be cost-effective given the scarcity of financial resources of Public Administrations (PA). In addition, they have to be specific to local data availability and land use regulations context.
The paper illustrates some results of a research that defines and tests a methodology to calculate and represent, at urban scale, the energy need of residential buildings and districts, based on the Italian data availability and the national regulations on energy efficiency in buildings. The methodology is designed with the necessary generality that enables it to be exported in different contexts.
After a short description of the Italian context regarding Municipal energy urban planning and available data, we describe the methodology framework based on a simple bottom-up engineering approach developed on GIS environment. Then we will discuss some results of a case study in order to define the methodology potential and limits and to outline further research.
Keywords: energy demand, , EPC, energy saving, urban regeneration tool
Centri storici e piani particolareggiati. Alcune esperienze di Antonello Monsù Scolaro, Alessandra Pili, Alessandra Urgu, Barbara Peri
No full textLa Lettera VII di Platone: comunanza di vita e persuasione come luogo della verità
No full textThis article seeks to contribute to the analysis of the philosophical excursus of Plato’s Seventh Letter and, in particular, to the conditions and assumptions that the author of the Letter considers necessary for the attainment of intellectual knowledge; knowledge, which is metaphorically presented with the famous image of the spark (ἐξαφθέν φῶς), like a sudden light springing forth from within the soul and feeding upon itself. Some introductory questions are examined in the first part of the study, while the problem of the conditions of intellectual knowledge is addressed in the second part. The article concludes by exploring the question of the objective dimension of knowledge: what does Plato propose in the Seventh Letter
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