1,266 research outputs found

    Nitric oxide production by Biomphalaria glabrata haemocytes: effects of Schistosoma mansoni ESPs and regulation through the extracellular signal-regulated kinase pathway

    Get PDF
    BACKGROUND: Schistosoma mansoni uses Biomphalaria glabrata as an intermediate host during its complex life cycle. In the snail, the parasite initially transforms from a miracidium into a mother sporocyst and during this process excretory-secretory products (ESPs) are released. Nitric oxide (NO) and its reactive intermediates play an important role in host defence responses against pathogens. This study therefore aimed to determine the effects of S. mansoni ESPs on NO production in defence cells (haemocytes) from schistosome-susceptible and schistosome-resistant B. glabrata strains. As S. mansoni ESPs have previously been shown to inhibit extracellular signal-regulated kinase (ERK) phosphorylation (activation) in haemocytes from susceptible, but not resistant, B. glabrata the regulation of NO output by ERK in these cells was also investigated. RESULTS: Haemocytes from resistant snails challenged with S. mansoni ESPs (20 mug/ml) over 5 h displayed an increase in NO production that was 3.3 times greater than that observed for unchallenged haemocytes; lower concentrations of ESPs (0.1-10 mug/ml) did not significantly increase NO output. In contrast, haemocytes from susceptible snails showed no significant change in NO output following challenge with ESPs at any concentration used (0.1-20 mug/ml). Western blotting revealed that U0126 (1 muM or 10 muM) blocked the phosphorylation (activation) status of ERK in haemocytes from both snail strains. Inhibition of ERK signalling by U0126 attenuated considerably intracellular NO production in haemocytes from both susceptible and resistant B. glabrata strains, identifying ERK as a key regulator of NO output in these cells. CONCLUSION: S. mansoni ESPs differentially influence intracellular NO levels in susceptible and resistant B. glabrata haemocytes, possibly through modulation of the ERK signalling pathway. Such effects might facilitate survival of S. mansoni in its intermediate host

    Approaches to issues of job regulation. A study at branch level in a white collar, public sector trade union. Available in 2 volumes.

    Get PDF
    This study examines the internal dynamics of white collar trade union branches in the public sector. The effects of a number of internal and external factors on branch patterns of action are evaluated. For the purposes of the study branch action is taken to be the approach to issues of job regulation, as expressed along the five dimensions of dependence on the outside trade union, focus in issues adopted, initiation of issues, intensity of action in issue pursuit and representativeness. The setting chosen for the study is four branches drawn from the same geographical area of the National and Local Government Officers Association. Branches were selected to give a variety in industry settings while controlling for the potentially influential variables of branch size, density of trade union membership and possession of exclusive representational rights in the employing organisation. Identical methods of data collection were used for each branch. The principal findings of the study are that the framework of national agreements and industry collective bargaining structures are strongly related to the industrial relations climate in the employing organisation and the structures of representation within the branch. Where agreements and collective bargaining structures formally restrict branch job regulation roles, there is a degree of devolution of bargaining authority from branch level negotiators to autonomous shop stewards at workplace level. In these circumstances industrial relations climate is characterised by a degree of informality in relationships between management and trade union activists. In turn, industrial relations climate and representative structures together with actor attitudes, have strong effects on all dimensions of approach to issues of job regulation

    Characterising post-medieval pottery production centres in Somerset

    Get PDF
    This is the final version. Available from the Medieval Pottery Research Group via the link in this recordPost-medieval pottery made in Somerset is distinct from wares produced elsewhere in the south-west of England. Recent experimental work and scientific analysis, combined with study of finds from fieldwork, has led to a more complete understanding of the nature of pottery production in Somerset, how it is possible to use mineralogical and stylistic evidence to distinguish between the three major areas of earthenware production and how production changes over time

    Indium mineralisation in SW England: Host parageneses and mineralogical relations

    Get PDF
    This is the author accepted manuscript and is available from Elsevier via http://dx.doi.org/http://dx.doi.org/. When the final article is assigned to volumes/issues of the publication, the Article in Press version will be removed replaced by the final version.The SW England ore region contains significant indium (In) in Early Permian granite-related skarn and lode parageneses and, to a lesser extent, Triassic epithermal “crosscourse” veins. Ore parageneses that predate granite emplacement (Devonian and Lower Carboniferous sedimentary exhalative and vein parageneses) are largely devoid of In. Cadmium (Cd) and gallium (Ga), in contrast, occur widely in all sulphide-bearing parageneses across the region with sphalerite concentrations locally reaching 1.74 wt% Cd and 1750 ppm Ga. Indium displays a strong affinity to sulphide-bearing magmatic-hydrothermal parageneses. It occurs in silicate-sulphide skarns, polymetallic sulphide lodes and sulphide-bearing portions of greisen-bordered sheeted vein systems and quartz-tourmaline lodes, veins and breccias across the region. Magnetite-silicate skarns and quartz-tourmaline lodes, veins and breccias that are devoid of sulphide, in contrast, were comparatively unfavourable for In precipitation. The highest In concentrations are found in mineral lodes associated with the Carnmenellis and St Agnes granites, which are the districts that had the highest historical production of Sn. Total In concentrations in these areas locally exceed 430 ppm, while concentrations elsewhere are systematically below 200 ppm. The principal In hosts are chalcopyrite, sphalerite and stannite group minerals with local concentrations within cassiterite and tennantite. No In was detected in löllingite, arsenopyrite, rutile, haematite, magnetite, tourmaline, biotite, chlorite, galena, bornite, chalcocite or pyrrhotite. Scattered concentrations in pyrite relate to impurities rather than incorporation by solid solution. Sphalerite locally contains up to 1.42 wt% In, chalcopyrite has up to 2200 ppm and stannite group minerals up to 6800 ppm. Although In concentrations are highest in sphalerite and stannite group minerals, chalcopyrite accounts for the majority of the In budget throughout most of the region. Roquesite and possibly dzhalindite or native In formed locally where In-bearing chalcopyrite or sphalerite have been replaced by bornite and quartz. The In partitioning between sphalerite and chalcopyrite varies broadly between 1:1 and 10:1. In the granite-related parageneses, the In deportment varies across the different parageneses, and this variation is systematically related to different sphalerite morphologies. Chalcopyrite contains most of the In budget within parageneses that have large, unzoned sphalerite grains with chalcopyrite disease or only sparse, minute grains of sphalerite. In contrast, zoned sphalerite without chalcopyrite disease carries the majority of the In budget in the evolved parts of the polymetallic sulphide lodes. Although chalcopyrite is also abundant here, it is much less significant as a host. Sporadic In was included in Triassic crosscourse veins as a result of interactions between migrating CaCl2-rich basinal brines and earlier formed granite-related parageneses. The interactions involved at least two distinct components: 1) Incorporation of clasts of magmatic-hydrothermal veins in crosscourse veins during faulting, and 2) Dissolution and re-precipitation of magmatic-hydrothermal vein minerals in crosscourse fluids. Local concentrations reach 140 ppm In. The region-wide dominance of chalcopyrite as an In host is unexpected and appears to be at variance with magmatic-hydrothermal parageneses elsewhere. This suggests that processing strategies that focus exclusively on sphalerite are likely to have little success. Detailed mineral deportment assessments must be a pre-requisite for the design of successful processing strategies in the region. Interestingly, we have no reason to believe that SW England is different to other regions with granite-related magmatic-hydrothermal parageneses, and it is possible that the global potential for In recovery from chalcopyrite has been underestimated. The magmatic-hydrothermal parageneses in SW England are comparable to the South China Tin Belt, Mount Pleasant, as well as Erzgebirge/Krušné Hory. Magmatic-hydrothermal fluids associated with peraluminous granites have developed a variety of skarn, greisen, lode and veins parageneses by interactions with their host rocks and contained fluids. Crosscourse epithermal mineralisation occurred as In was transported by CaCl2-rich basinal brines in a similar manner as In-bearing veins in the West Shropshire ore field

    Praziquantel coverage in schools and communities targeted for the elimination of urogenital schistosomiasis in Zanzibar: a cross-sectional survey

    Get PDF
    © 2015 Knopp et al. Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. The attached file is the published version of the article

    Application of near infrared sensors to preconcentration of hydrothermally-formed copper ore

    Get PDF
    Article© 2015. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/Near infrared sensors can be a very useful technique for the qualitative analysis of complex ores, and thus could be useful for the preconcentration of ores. In this paper, individual particles of hydrothermally-formed copper ore sampled from a mine in the Los Pozos mining district, northern Chile, were classified as product, middling and waste based on their near infrared response. The classification of copper bearing minerals (product) from gangue (waste) was considered for vibration combination bands at longer wavelengths from 2000 to 2400 nm. This region exhibits characteristic features for carbonates and hydroxyl gangue bearing minerals. The near infrared features at 1400 and 1900 nm were not considered favourable for classification and subsequent discrimination because they can be influenced by moisture and other environmental factors and are easily suppressed by iron-rich minerals. Two near infrared preconcentration strategies were applied for particle discrimination. Results indicate that targeting only the calcite (carbonate) dominated particles for discrimination as waste provided the best option for preconcentration. The near infrared discrimination analysis correlates well with mineralogical (QEMSCAN® and XRD) and elemental (XRF) data classification. The results indicate that near infrared spectroscopy is a suitable preconcentration method for supergene copper ore

    Molecular characterization of freshwater snails in the genus Bulinus: a role for barcodes?

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Reliable and consistent methods are required for the identification and classification of freshwater snails belonging to the genus <it>Bulinus </it>(Gastropoda, Planorbidae) which act as intermediate hosts for schistosomes of both medical and veterinary importance. The current project worked towards two main objectives, the development of a cost effective, simple screening method for the routine identification of <it>Bulinus </it>isolates and the use of resultant sequencing data to produce a model of relationships within the group.</p> <p>Results</p> <p>Phylogenetic analysis of the DNA sequence for a large section (1009 bp) of the mitochondrial gene cytochrome oxidase subunit 1 (<it>cox1</it>) for isolates of <it>Bulinus </it>demonstrated superior resolution over that employing the second internal transcribed spacer <it>(its2</it>) of the ribosomal gene complex. Removal of transitional substitutions within <it>cox1 </it>because of saturation effects still allowed identification of snails at species group level. Within groups, some species could be identified with ease but there were regions where the high degree of molecular diversity meant that clear identification of species was problematic, this was particularly so within the <it>B. africanus </it>group.</p> <p>Conclusion</p> <p>The sequence diversity within <it>cox1 </it>is such that a barcoding approach may offer the best method for characterization of populations and species within the genus from different geographical locations. The study has confirmed the definition of some accepted species within the species groups but additionally has revealed some unrecognized isolates which underlines the need to use molecular markers in addition to more traditional methods of identification. A barcoding approach based on part of the <it>cox1 </it>gene as defined by the Folmer primers is proposed.</p

    Elimination of Schistosomiasis Transmission in Zanzibar: Baseline Findings before the Onset of a Randomized Intervention Trial.

    Get PDF
    Gaining and sustaining control of schistosomiasis and, whenever feasible, achieving local elimination are the year 2020 targets set by the World Health Organization. In Zanzibar, various institutions and stakeholders have joined forces to eliminate urogenital schistosomiasis within 5 years. We report baseline findings before the onset of a randomized intervention trial designed to assess the differential impact of community-based praziquantel administration, snail control, and behavior change interventions. In early 2012, a baseline parasitological survey was conducted in ∼20,000 people from 90 communities in Unguja and Pemba. Risk factors for schistosomiasis were assessed by administering a questionnaire to adults. In selected communities, local knowledge about schistosomiasis transmission and prevention was determined in focus group discussions and in-depths interviews. Intermediate host snails were collected and examined for shedding of cercariae. The baseline Schistosoma haematobium prevalence in school children and adults was 4.3% (range: 0-19.7%) and 2.7% (range: 0-26.5%) in Unguja, and 8.9% (range: 0-31.8%) and 5.5% (range: 0-23.4%) in Pemba, respectively. Heavy infections were detected in 15.1% and 35.6% of the positive school children in Unguja and Pemba, respectively. Males were at higher risk than females (odds ratio (OR): 1.45; 95% confidence interval (CI): 1.03-2.03). Decreasing adult age (OR: 1.04; CI: 1.02-1.06), being born in Pemba (OR: 1.48; CI: 1.02-2.13) or Tanzania (OR: 2.36; CI: 1.16-4.78), and use of freshwater (OR: 2.15; CI: 1.53-3.03) showed higher odds of infection. Community knowledge about schistosomiasis was low. Only few infected Bulinus snails were found. The relatively low S. haematobium prevalence in Zanzibar is a promising starting point for elimination. However, there is a need to improve community knowledge about disease transmission and prevention. Control measures tailored to the local context, placing particular attention to hot-spot areas, high-risk groups, and individuals, will be necessary if elimination is to be achieved

    Geotechnical and mineralogical characterisations of marine dredged sediments before and after stabilisation to optimise their use as a road material

    Get PDF
    ArticleThis is the author accepted manuscript. The final version is available from Taylor & Francis via the DOI in this record.Dredging activities to extend, deepen and maintain access to harbours generate significant volumes of waste dredged material. Some ways are investigated to add value to these sediments. One solution described here is their use in road construction following treatment with hydraulic binders. This paper presents the characterisation of four sediments, in their raw state and after 90 days of curing following stabilisation treatment with lime and cement, using a combination of novel and established analytical techniques to investigate subsequent changes in mineralogy. These sediments are classified as fine, moderately to highly organic and highly plastic and their behaviour is linked to the presence of smectite clays. The main minerals found in the sediments using X-rays diffraction (XRD) and automated mineralogy are quartz, calcite, feldspars, aluminium silicates, pyrite and halite. Stabilisation was found to improve the mechanical performances of all the sediments. The formation of cementitious hydrates was not specifically detected using automated mineralogy or XRD. However, a decrease in the percentage volume of aluminium silicates and aluminium-iron silicates and an increase of the percentage volume of feldspars and carbonates was observed.The authors thank the all the partners having participate to the dredging operations; Lhoist and Lafarge for their technical and scientifical supports; Europe, European Regional Development Fund (ERDF), Interreg IVA and Regional Council of Basse-Normandie for their financial support to the Sustainable and Environmental Treatment And Reuse of Marine Sediment (SETARMS) project
    corecore