61,688 research outputs found
Enteropathogenic Escherichia coli infection: history and clinical aspects
No full textDiarrhoeagenic Escherichia coli remains an important cause of diarrhoeal disease worldwide. In terms of global public health, enteropathogenic E. coli (EPEC) and enterotoxigenic E. coli are the most important. However, enterohaemorrhagic E. coli has emerged as a cause of disease in developed countries in recent years, and a number of large outbreaks have been reported. Therefore, the importance of research into diarrhoeagenic E. coli remains an important issue. EPEC is the most widespread of the diarrhoeagenic E. coli and provides a good virulence model for other E. coli infections, as well as other pathogenic bacteria. Although the virulence mechanisms of E. coli are now better understood, there remains much to be learned before effective treatments can be developed. Type III secretion mechanisms, the locus of enterocyte effacement and various toxins are all involved in the pathogenesis of the various diarrhoeagenic E. coli and may provide targets for future therapies. This review aims to provide an update on the worldwide problem of diarrhoeagenic E. coli by focusing on EPEC, and describes the history of the organism, its incidence and the clinical aspects of infection.</p
Virulence of enteropathogenic Escherichia coli, a global pathogen
No full textEnteropathogenic Escherichia coli (EPEC) remains an important cause of diarrheal disease worldwide. Research into EPEC is intense and provides a good virulence model of other E. coli infections as well as other pathogenic bacteria. Although the virulence mechanisms are now better understood, they are extremely complex and much remains to be learnt. The pathogenesis of EPEC depends on the formation of an ultrastructural lesion in which the bacteria make intimate contact with the host apical enterocyte membrane. The formation of this lesion is a consequence of the ability of EPEC to adhere in a localized manner to the host cell, aided by bundle-forming pili. Tyrosine phosphorylation and signal transduction events occur within the host cell at the lesion site, leading to a disruption of the host cell mechanisms and, consequently, to diarrhea. These result from the action of highly regulated EPEC secreted proteins which are released via a type III secretion system, many genes of which are located within a pathogenicity island known as the locus of enterocyte effacement. Over the last few years, dramatic increases in our knowledge of EPEC virulence have taken place. This review therefore aims to provide a broad overview of and update to the virulence aspects of EPEC.</p
Reclaiming and Making Places of Distinction through Landscape Architecture
No full textLandscape architects create distinctive places in contemporary urban environments by responding to local history, the physical reality of the site, and social context. How well do these projects reveal or create a “sense of place”? This chapter considers Relph’s comment that built environment professionals have “an important role…to play in reclaiming and making places” (Relph 1993, p38). The discussion explores two sites in Sydney that exemplify how landscape architects worked “from the inside out” to produce two unique and well-used urban parks, whose meanings and significance are emerging
The safety and effectiveness of different methods of ear wax removal: a systematic review and economic evaluation
No full textEar wax (cerumen) is a natural secretion produced to protect the inner ear from dirt and other fragments by moving these particles towards the outer ear. If this process does not happen properly, wax may build up causing blockage in the ear canal and the possibility of impaction. People with a build up of ear wax may suffer from hearing loss, discomfort and, on occasions, infection. It may present problems in assessing hearing, blocking the view of the ear drum during medical examination and interfering with the fitting or function of hearing aids. Although it is thought to affect between 2% and 6% of the population in the England and Wales, some groups may be at a higher risk, such as those using hearing aids or with small ear canals and/or skin conditions. Recurrence is thought to be high among some of these groups. The consequences of the build up of ear wax in the ear canal are thought to be a common reason for consultation and cost in general practice with over 2 million consultations per year in the NHS.Methods of removal of ear wax include drops, flushing with water in general practice, and removal with suction or probes in specialist clinics. The relative safety and benefits of these different methods of removal remains uncertain. This research will systematically review published and unpublished evidence on the clinical and cost effectiveness of different methods for the removal of ear wax. Where appropriate, it will develop an economic model using data from this systematic review and other relevant sources to estimate the relative costs and benefits of different methods. In addition, the project will provide recommendations for future research to try to help answer any remaining areas of uncertainty
Tyrosine phosphorylation in Escherichia coli
No full textThe phosphorylation on tyrosine of a protein in Escherichia coli both in vivo and in vitro was revealed by recognition by anti-phosphotyrosine antibodies, labelling with [gamma-32P]ATP, and phosphoamino acid analysis. This protein, which we name TypA, is the product of the o591 reading frame as revealed by N-terminal sequencing and antibody cross-reactivity. Inactivation of typA altered the patterns of protein synthesis during both exponential growth and carbon starvation. These alterations included the disappearance of an acidic isoform of both the universal stress protein UspA and carbon starvation protein Csp15, and increased synthesis of the histone-like protein H-NS. The sequence of TypA from strain K-12 differs from that of an enteropathogenic strain in six amino acid residues and the protein is three residues shorter. We propose that TypA interacts with global regulatory networks and that its phosphorylation may be relevant to pathogenesis.</p
A 2 h periodic variation in the low-mass X-ray binary Ser X-1
No full textSpectroscopy of the low-mass X-ray binary Ser X-1 using the Gran Telescopio Canarias have revealed a ?2 h periodic variability that is present in the three strongest emission lines. We tentatively interpret this variability as due to orbital motion, making it the first indication of the orbital period of Ser X-1. Together with the fact that the emission lines are remarkably narrow, but still resolved, we show that a main-sequence K dwarf together with a canonical 1.4 M? neutron star gives a good description of the system. In this scenario, the most likely place for the emission lines to arise is the accretion disc, instead of a localized region in the binary (such as the irradiated surface or the stream-impact point), and their narrowness is due instead to the low inclination (?10°) of Ser X-1
Past and future sea-level rise along the coast of North Carolina, USA
No full textWe evaluate relative sea level (RSL) trajectories for North Carolina, USA, in the context of tide-gauge measurements and geological sea-level proxy reconstructions spanning the last ∼11,000 years. RSL rise was fastest (∼7 mm/yr) during the early Holocene and slowed over time with the end of the deglaciation. During the pre-Industrial Common Era (i.e., 0–1800 CE), RSL rise (∼0.7 to 1.1 mm/yr) was driven primarily by glacio-isostatic adjustment, though dampened by tectonic uplift along the Cape Fear Arch. Ocean/atmosphere dynamics caused centennial variability of up to ∼0.6 mm/yr around the long-term rate. It is extremely likely (probability P = 0.95) that 20th century RSL rise at Sand Point, NC, (2.8 ± 0.5 mm/yr) was faster than during any other century in at least 2,900 years. Projections based on a fusion of process models, statistical models, expert elicitation, and expert assessment indicate that RSL at Wilmington, NC, is very likely (P = 0.90) to rise by 42–132 cm between 2000 and 2100 under the high-emissions RCP 8.5 pathway. Under all emission pathways, 21st century RSL rise is very likely (P > 0.90) to be faster than during the 20th century. Due to RSL rise, under RCP 8.5, the current ‘1-in-100 year’ flood is expected at Wilmington in ∼30 of the 50 years between 2050-2100.The final publication is available at Springer via http://dx.doi.org/10.1007/s10584-015-1451-xPeer reviewe
Lipschitz free p-spaces for 0 < p < 1
No full textThis paper initiates the study of the structure of a new class of p-Banach spaces, 0 <p < 1, namely the Lipschitz free p-spaces (alternatively called Arens—Eells p-spaces) Fp(M) over p-metric spaces. We systematically develop the theory and show that some results hold as in the case of p = 1, while some new interesting phenomena appear in the case 0 <p < 1 which have no analogue in the classical setting. For the former, we, e.g., show that the Lipschitz free p-space over a separable ultrametric space is isomorphic to ℓp for all 0 <p ≤ 1. On the other hand, solving a problem by the first author and N. Kalton, there are metric spaces N⊂M such that the natural embedding from Fp(N) to Fp(M) is not an isometry.F. Albiac acknowledges the support of the Spanish Ministry for Economy and Competitivity Grants MTM2014-53009-P for Análisis Vectorial, Multilineal y Aplicaciones, and MTM2016-76808-P for Operators, lattices, and structure of Banach spaces as well as the Spanish Ministry for Science and Innovation under Grant PID2019-1077701GB-I00. J. L. Ansorena acknowledges the support of the Spanish Ministry for Economy and Competitivity Grant MTM2014-53009-P for Análisis Vectorial, Multilineal y Aplicaciones. M. Cúth has been supported by Charles University Research program No. UNCE/SCI/023 and by the Research grant GACR 17-04197Y. M. Doucha was supported by the GACR project 16-34860L and RVO: 67985840
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