992 resultados para Distal Site


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There is currently an increased interest of Government and Industry in the UK, as well as at the European Community level and International Agencies (i.e. Department of Energy, American International Energy Agency), to improve the performance and uptake of Ground Coupled Heat Pumps (GCHP), in order to meet the 2020 renewable energy target. A sound knowledge base is required to help inform the Government Agencies and advisory bodies; detailed site studies providing reliable data for model verification have an important role to play in this. In this study we summarise the effect of heat extraction by a horizontal ground heat exchanger (installed at 1 m depth) on the soil physical environment (between 0 and 1 m depth) for a site in the south of the UK. Our results show that the slinky influences the surrounding soil by significantly decreasing soil temperatures. Furthermore, soil moisture contents were lower for the GCHP soil profile, most likely due to temperature-gradient related soil moisture migration effects and a decreased hydraulic conductivity, the latter as a result of increased viscosity (caused by the lower temperatures for the GCHP soil profile). The effects also caused considerable differences in soil thermal properties. This is the first detailed mechanistic study conducted in the UK with the aim to understand the interactions between the soil, horizontal heat exchangers and the aboveground environment. An increased understanding of these interactions will help to achieve an optimum and sustainable use of the soil heat resources in the future. The results of this study will help to calibrate and verify a simulation model that will provide UK-wide recommendations to improve future GCHP uptake and performance, while safeguarding the soil physical resources.

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The accurate prediction of the biochemical function of a protein is becoming increasingly important, given the unprecedented growth of both structural and sequence databanks. Consequently, computational methods are required to analyse such data in an automated manner to ensure genomes are annotated accurately. Protein structure prediction methods, for example, are capable of generating approximate structural models on a genome-wide scale. However, the detection of functionally important regions in such crude models, as well as structural genomics targets, remains an extremely important problem. The method described in the current study, MetSite, represents a fully automatic approach for the detection of metal-binding residue clusters applicable to protein models of moderate quality. The method involves using sequence profile information in combination with approximate structural data. Several neural network classifiers are shown to be able to distinguish metal sites from non-sites with a mean accuracy of 94.5%. The method was demonstrated to identify metal-binding sites correctly in LiveBench targets where no obvious metal-binding sequence motifs were detectable using InterPro. Accurate detection of metal sites was shown to be feasible for low-resolution predicted structures generated using mGenTHREADER where no side-chain information was available. High-scoring predictions were observed for a recently solved hypothetical protein from Haemophilus influenzae, indicating a putative metal-binding site.

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World-wide structural genomics initiatives are rapidly accumulating structures for which limited functional information is available. Additionally, state-of-the art structural prediction programs are now capable of generating at least low resolution structural models of target proteins. Accurate detection and classification of functional sites within both solved and modelled protein structures therefore represents an important challenge. We present a fully automatic site detection method, FuncSite, that uses neural network classifiers to predict the location and type of functionally important sites in protein structures. The method is designed primarily to require only backbone residue positions without the need for specific side-chain atoms to be present. In order to highlight effective site detection in low resolution structural models FuncSite was used to screen model proteins generated using mGenTHREADER on a set of newly released structures. We found effective metal site detection even for moderate quality protein models illustrating the robustness of the method.

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In cattle, the lymphoid rich regions of the rectal-anal mucosa at the terminal rectum are the preferred site for Escherichia coli O157:H7 colonisation. All cattle infected by rectal swab administration demonstrate long-term E. coli O157:H7 colonisation, whereas orally challenged cattle do not demonstrate long-term E. coli O157:H7 colonisation in all animals. Oral, but not rectal challenge of sheep with E. coli O157:H7 has been reported, but an exact site for colonisation in sheep is unknown. To determine if E. coli O157:H7 can effectively colonise the ovine terminal rectum, in vitro organ culture (IVOC) was initiated. Albeit sparsely, large, densely packed E. coli O157:H7 micro-colonies were observed on the mucosa of ovine and control bovine terminal rectum explants. After necropsy of orally inoculated lambs, bacterial enumeration of the proximal and distal gastrointestinal tract did suggest a preference for E. coli O157:H7 colonisation at the ovine terminal rectum, albeit for both lymphoid rich and non-lymphoid sites. As reported for cattle, rectal inoculation studies were then conducted to determine if all lambs would demonstrate persistent colonisation at the terminal rectum. After necropsy of E. coli O157:H7 rectally inoculated lambs, most animals were not colonised at gastrointestinal sites proximal to the rectum, however, large densely packed micro-colonies of E. coli O157:H7 were observed on the ovine terminal rectum mucosa. Nevertheless, at the end point of the study (day 14), only one lamb had E. coli O157:H7 micro-colonies associated with the terminal rectum mucosa. A comparison of E. coli O157:H7 shedding yielded a similar pattern of persistence between rectally and orally inoculated lambs. The inability of E. coli O157:H7 to effectively colonise the terminal rectum mucosa of all rectally inoculated sheep in the long term, suggests that E. coli O157:H7 may colonise this site, but less effectively than reported previously for cattle.

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The estimation of prediction quality is important because without quality measures, it is difficult to determine the usefulness of a prediction. Currently, methods for ligand binding site residue predictions are assessed in the function prediction category of the biennial Critical Assessment of Techniques for Protein Structure Prediction (CASP) experiment, utilizing the Matthews Correlation Coefficient (MCC) and Binding-site Distance Test (BDT) metrics. However, the assessment of ligand binding site predictions using such metrics requires the availability of solved structures with bound ligands. Thus, we have developed a ligand binding site quality assessment tool, FunFOLDQA, which utilizes protein feature analysis to predict ligand binding site quality prior to the experimental solution of the protein structures and their ligand interactions. The FunFOLDQA feature scores were combined using: simple linear combinations, multiple linear regression and a neural network. The neural network produced significantly better results for correlations to both the MCC and BDT scores, according to Kendall’s τ, Spearman’s ρ and Pearson’s r correlation coefficients, when tested on both the CASP8 and CASP9 datasets. The neural network also produced the largest Area Under the Curve score (AUC) when Receiver Operator Characteristic (ROC) analysis was undertaken for the CASP8 dataset. Furthermore, the FunFOLDQA algorithm incorporating the neural network, is shown to add value to FunFOLD, when both methods are employed in combination. This results in a statistically significant improvement over all of the best server methods, the FunFOLD method (6.43%), and one of the top manual groups (FN293) tested on the CASP8 dataset. The FunFOLDQA method was also found to be competitive with the top server methods when tested on the CASP9 dataset. To the best of our knowledge, FunFOLDQA is the first attempt to develop a method that can be used to assess ligand binding site prediction quality, in the absence of experimental data.

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Land surface albedo is dependent on atmospheric state and hence is difficult to validate. Over the UK persistent cloud cover and land cover heterogeneity at moderate (km-scale) spatial resolution can also complicate comparison of field-measured albedo with that derived from instruments such as the Moderate Resolution Imaging Spectrometer (MODIS). A practical method of comparing moderate resolution satellite-derived albedo with ground-based measurements over an agricultural site in the UK is presented. Point measurements of albedo made on the ground are scaled up to the MODIS resolution (1 km) through reflectance data obtained at a range of spatial scales. The point measurements of albedo agreed in magnitude with MODIS values over the test site to within a few per cent, despite problems such as persistent cloud cover and the difficulties of comparing measurements made during different years. Albedo values derived from airborne and field-measured data were generally lower than the corresponding satellite-derived values. This is thought to be due to assumptions made regarding the ratio of direct to diffuse illumination used when calculating albedo from reflectance. Measurements of albedo calculated for specific times fitted closely to the trajectories of temporal albedo derived from both Systeme pour l'Observation de la Terre (SPOT) Vegetation (VGT) and MODIS instruments.

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Archaeological excavations alongside the river Wandle in Wallington produced evidence of the environmental history and human exploitation of the area. The recovery of a large assemblage of struck flint provided information on the nature of the prehistoric activities represented, while a detailed environmental archaeological programme permitted an examination of both the local sediment successions and thus an opportunity to reconstruct the environmental history of the site. The site revealed a complex sedimentary sequence deposited in riverine conditions, commencing during the early Holocene (from c 10,000 years before present) and continuing through the late Holocene (c last 3000 years). Large flint nodules were washed by the river onto the site where they were procured and worked by Mesolithic and Bronze Age communities. Potentially usable nodules had been tested, and suitable pieces completely reduced, while the majority of useful flakes and blades had been removed for use elsewhere. Small numbers of retouched pieces, such as scrapers and piercers, indicate that domestic activities took place nearby. By the Saxon period the site had begun to stabilise, although it remained marshy and probably peripheral to habitation. Two pits from this period were excavated, one of which contained an antler pick. A small quantity of cereal grain also suggests that cultivated land lay in the vicinity of the site. During the 19th century a mill race was dug across the site, redirecting water from the river Wandle, which resulted in episodic flooding.

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Enterohaemorrhagic Escherichia coli O157 : H7 infections of man have been associated with consumption of unpasteurized goat's milk and direct contact with kid goats on petting farms, yet little is known about colonization of goats with this organism. To assess the contribution of flagella and intimin of E coli O157 : H7 in colonization of the goat, 8-week-old conventionally reared goats were inoculated orally in separate experiments with 1 X 10(10) c.f.u. of a non-verotoxigenic strain of E coli O157: H7 (strain NCTC 12900 Nal(r)), an aflagellate derivative (DMB1) and an intimin-deficient derivative (DMB2). At 24 In after inoculation, the three E coli O157 : H7 strains were shed at approximately 5 X 1 04 c.f.u. (g faeces)(-1) from all animals. Significantly fewer intimin-deficient bacteria were shed only on days 2 (P = 0(.)003) and 4 (P = 0(.)014), whereas from day 7 to 29 there were no differences. Tissues from three animals inoculated with wild-type E coli O157 : H7 strain NCTC 12900 Nalr were sampled at 24,48 and 96 In after inoculation and the organism was cultured from the large intestine of all three animals and from the duodenum and ileum of the animal examined at 96 h. Tissues were examined histologically but attaching-effacing (AE) lesions were not observed at any intestinal site of the animals examined at 24 or 48 In. However, the animal examined at 96 h, which had uniquely shed approximately 1 x 10(7) E coli O157: H7 (g faeces)(-1) for the preceding 3 days, showed a heavy, diffuse infection with cryptosporidia. and abundant, multifocal AE lesions in the distal colon, rectum and at the recto-anal junction. These AE lesions were confirmed by immunohistochemistry to be associated with E coli O157: H7.

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The membrane-bound form of mammalian aminopeptidase P (AP-P; EC 3.4. 11.9) is a mono-zinc-containing enzyme that lacks any of the typical metal binding motifs found in other zinc metalloproteases. To identify residues involved in metal binding and catalysis, sequence and structural information was used to align the sequence of porcine membrane-bound AP-P with other members of the peptidase clan MG, including Escherichia coli AP-P and methionyl aminopeptidases. Residues predicted to be critical for activity were mutated and the resultant proteins were expressed in COS-1 cells. Immunoelectrophoretic blot analysis was used to compare the levels of expression of the mutant proteins, and their ability to hydrolyze bradykinin and Gly-Pro-hydroxyPro was assessed. Asp449, Asp460, His523, Glu554, and Glu568 are predicted to serve as metal ion ligands in the active site, and mutagenesis of these residues resulted in fully glycosylated proteins that were catalytically inactive. Mutation of His429 and His532 also resulted in catalytically inactive proteins, and these residues, by analogy with E. coli AP-P, are likely to play a role in shuttling protons during catalysis. These studies indicate that mammalian membrane-bound AP-P has an active-site configuration similar to that of other members of the peptidase clan MG, which is compatible with either a dual metal ion model or a single metal ion in the active site. The latter model is consistent, however, with the known metal stoichiometry of both the membrane-bound and cytosolic forms of AP-P and with a recently proposed model for methionyl aminopeptidase.

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Microbial metabolism of proteins and amino acids by human gut bacteria generates a variety of compounds including phenol, indole, and sulfur compounds and branched chain fatty acids, many of which have been shown to elicit a toxic effect on the lumen. Bacterial fermentation of amino acids and proteins occurs mainly in the distal colon, a site that is often fraught with symptoms from disorders including ulcerative colitis (UC) and colorectal cancer (CRC). In contrast to carbohydrate metabolism by the gut microbiota, proteolysis is less extensively researched. Many metabolites are low molecular weight, volatile compounds. This review will summarize the use of analytical methods to detect and identify compounds in order to elucidate the relationship between specific dietary proteinaceous substrates, their corresponding metabolites, and implications for gastrointestinal health.

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Numerous Building Information Modelling (BIM) tools are well established and potentially beneficial in certain uses. However, issues of adoption and implementation persist, particularly for on-site use of BIM tools in the construction phase. We describe an empirical case-study of the implementation of an innovative ‘Site BIM’ system on a major hospital construction project. The main contractor on the project developed BIM-enabled tools to allow site workers using mobile tablet personal computers to access design information and to capture work quality and progress data on-site. Accounts show that ‘Site BIM’, while judged to be successful and actively supporting users, was delivered through an exploratory and emergent development process of informal prototyping. Technical IT skills were adopted into the construction project through personal relationships and arrangements rather than formal processes. Implementation was driven by construction project employees rather than controlled centrally by the corporate IT function.

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Although grasslands are crucial habitats for European butterflies, large-scale declines in quality and area have devastated many species. Grassland restoration can contribute to the recovery of butterfly populations, although there is a paucity of information on the long-term effects of management. Using eight UK data sets (9-21 years), we investigate changes in restoration success for (1) arable reversion sites, were grassland was established on bare ground using seed mixtures, and (2) grassland enhancement sites, where degraded grasslands are restored by scrub removal followed by the re-instigation of cutting/grazing. We also assessed the importance of individual butterfly traits and ecological characteristics in determining colonisation times. Consistent increases in restoration success over time were seen for arable reversion sites, with the most rapid rates of increase in restoration success seen over the first 10 years. For grasslands enhancement there were no consistent increases in restoration success over time. Butterfly colonisation times were fastest for species with widespread host plants or where host plants established well during restoration. Low mobility butterfly species took longer to colonise. We show that arable reversion is an effective tool for the management of butterfly communities. We suggest that as restoration takes time to achieve, its use as a mitigation tool against future environmental change (i.e. by decreasing isolation in fragmented landscapes) needs to take into account such time lags.

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The crystal structure of the ruthenium DNA ‘light-switch’ complex -[Ru(TAP)2(11-Cl-dppz)]2+ (TAP = tetraazaphenanthrene, dppz = dipyrido[3,2-a':2',3'-c]phenazine)) bound to the oligonucleotide duplex d(TCGGCGCCGA)2 is reported. The synthesis of the racemic ruthenium complex is described for the first time, and the racemate was used in this study. The crystal structure, at atomic resolution (1.0 Å), shows one ligand as a wedge in the minor groove, resulting in the 51 kinking of the double helix, as with the parent lambda-[Ru(TAP)2(dppz)]2+. Each complex binds to one duplex by intercalation of the dppz ligand and also by semi-intercalation of one of the orthogonal TAP ligands into a second symmetrically equivalent duplex. The 11-Cl substituent binds with the major component (66%) oriented with the 11-chloro substituent on the purine side of the terminal step of the duplex.