947 research outputs found
Depolarization and decreased surface expression of K+ channels contribute to NSAID-inhibition of intestinal restitution
No full textNon-steroidal anti-inflammatory drugs (NSAIDs) contribute to gastrointestinal ulcer formation by inhibiting epithelial cell migration and mucosal restitution; however, the drug-affected signaling pathways are poorly defined. We investigated whether NSAID inhibition of intestinal epithelial migration is associated with depletion of intracellular polyamines, depolarization of membrane potential (Em) and altered surface expression of K+ channels. Epithelial cell migration in response to the wounding of confluent IEC-6 and IEC-Cdx2 monolayers was reduced by indomethacin (100μM), phenylbutazone (100μM) and NS-398 (100μM) but not by SC-560 (1μM). NSAID-inhibition of intestinal cell migration was not associated with depletion of intracellular polyamines. Treatment of IEC-6 and IEC-Cdx2 cells with indomethacin, phenylbutazone and NS-398 induced significant depolarization of Em, whereas treatment with SC-560 had no effect on Em. The Em of IEC-Cdx2 cells was: −38.5±1.8mV under control conditions; −35.9±1.6mV after treatment with SC-560; −18.8±1.2mV after treatment with indomethacin; and −23.7±1.4mV after treatment with NS-398. Whereas SC-560 had no significant effects on the total cellular expression of Kv1.4 channel protein, indomethacin and NS-398 decreased not only the total cellular expression of Kv1.4, but also the cell surface expression of both Kv1.4 and Kv1.6 channel subunits in IEC-Cdx2. Both Kv1.4 and Kv1.6 channel proteins were immunoprecipitated by Kv1.4 antibody from IEC-Cdx2 lysates, indicating that these subunits co-assemble to form heteromeric Kv channels. These results suggest that NSAID inhibition of epithelial cell migration is independent of polyamine-depletion, and is associated with depolarization of Em and decreased surface expression of heteromeric Kv1 channels.ID: S0006295207001931; M3: Article; Accession Number: S0006295207001931; Author: L.C. Freeman (b); Author: D.F. Narvaez (a); Author: A. McCoy (a); Author: F.B. von Stein (c); Author: S. Young (b); Author: K. Silver (a); Author: S. Ganta (b); Author: D. Koch (b); Author: R. Hunter (b); Author: R.F. Gilmour (c); Author: J.D. Lillich (a, ⁎); Affiliation: Department of Clinical Sciences, Kansas State University, Manhattan, KS 66506, United States; Affiliation: Department of Anatomy and Physiology, Kansas State University, Manhattan, KS 66506, United States; Affiliation: Department of Biomedical Sciences, Cornell University, Ithaca, NY 14853, United States; Keyword: Non-steroidal anti-inflammatory drugs; Keyword: Intestinal epithelial cells; Keyword: Membrane potential; Keyword: Potassium channels; Number of Pages: 12; Language: English;Source type: Electronic(1)http://search.ebscohost.com/login.aspx?direct=true&db=edselp&AN=S0006295207001931&site=eds-live&scope=sit
Microbial and metabolic diversity of anaerobic D-galacturonate fermentation
No full textOver the past decade the demand for technology which can make our global economy more sustainable has increased exponentially. In the field of biotechnology, one of the many advancements is focussed on the conversion of agricultural waste streams towards commodity chemicals. Plant biomass can be an environmental and sustainable alternative for the use of petrochemical substrates, with a special interest towards processes which use plant biomass in waste streams rather than currently used feedstocks, such as corn and sugarcane molasses that are competing with food production.BT/Industriele Microbiologi
Nano zero valent iron amended ceramic pot filters for enhanced virus and arsenic removal
No full textWorldwide 748 million people lacked access to improved sources of drinking water in 2014, of this group almost a quarter relies on untreated surface water (WHO & Unicef, 2014). According to the WHO, simple, socially accepted and low-cost household water treatment systems (HWTS), such as the Ceramic Pot Filter (CPF), can provide a solution for reliable drinking water on the short term. Although CPFs are used worldwide and are generally effective with regard to bacteria removal, they can in most cases not be indicated by the WHO as a “protective” HWTS, since the virus removal is insufficient. Another limitation of the CPF is the incapability of removing arsenic. Prolonged ingestion of water with elevated arsenic levels can lead to severe health issues including dermal lesions and various types of cancers (WHO, 2011b). The objective of this study was therefore to provide reliable experimental data to investigate whether it is feasible to extend the capabilities of CPFs with arsenic removal properties and enhanced virus inactivation by the incorporation of nano Zero Valent Iron (nZVI), which is a well-known arsenic adsorbent and has also potential capabilities for virus reduction. As a basis for the research approach, the following sub-objectives were formulated: (i) study the arsenic adsorption capacities nZVI amended CPFs, (ii) determine the microbiological inactivation efficiency by nZVI amended CPFs, (iii) evaluate the leaching of the incorporated nZVI and (iv) provide knowledge on the effect of incorporating nZVI into CPFs before firing. In this study Ceramic Disk Filters (CDFs) manufactured by combining clay soil with water and sawdust, pressing them in a disk shape and, firing them. Additionally, metals (nZVI, Composite Iron Matrix powder or silver nanoparticles (nAg)) were added to the clay mixture before firing, to obtain an iron content of 0.05%, 0.5% or 5% based on the weight of a dry disk. The manufactured CDFs were tested based on the following established requirements: (i) arsenic must be removed to below the provisional WHO guideline of 10 ?g/L, (ii) for bacteria a LRV of 2 or greater is required, (ii) for viruses a LRV of 3 or greater is required, (iv) the leached amount of metals must not exceed the WHO guidelines and (v) CDFs should have a flow rate of 0.08-0.24 L/h, which corresponds to 1-3 L/h for a full-size CPF. The removal of bacteria and viruses was quantified by loading the CDFs with test water with Escherichia coli and MS2 bacteriophages, as indicator organisms for bacteria and viruses, respectively. During this filter experiment also the metal leaching from the CDFs was evaluated, an arsenic breakthrough experiment was performed and the flow rates were measured. Furthermore, batch experiments were conducted with ground CDFs, both fired and unfired, to get more insight on the capabilities of the adsorption and inactivation of MS2 bacteriophages and the removal of arsenic, and to study the consequences of firing nZVI into the CDFs. Moreover, knowledge was obtained on the effect of firing nZVI into ceramic material by means of X-ray diffraction (XRD), 57Fe Mössbauer spectroscopy, optical microscopy and Scanning Electron Microscope – Energy Dispersive X-ray (SEM-EDX). The main findings, with regard to the requirements for a CPF, were: (i) although this study showed that ZVI on itself is an effective arsenic adsorbent an immediate total arsenic breakthrough of 200 ?g/L was observed for the CDFs with 5% nZVI; (ii) all CDFs, except the filter with 0.05% nZVI, were able to remove E. coli sufficiently to meet the requirements for bacteria removal (LRV 0.75-4.28); (iii) MS2 bacteriophages were poorly removed (LRV 0.11-0.24) (iv) there is no health-based guideline of the WHO for iron and the leached silver stayed far below the maximum WHO guideline of 0.1 mg/L; (v) the translated flow rates for CPFs were for all type filters higher than the requirement of 1-3 L/h (3.4 – 15.6 L/h), except for the filter with 0.05% nAg (1.5 L/h). Overall, it can thus be concluded that it is not recommended to incorporate nZVI in CPFs before firing with the purpose to enhance the removal of arsenic and viruses. Although, ZVI on itself is well capable of removing arsenic, especially at nano-scale, it was found that when it is incorporated into clay it looses effectiveness and when the clay is fired even more. In the batch experiments the unfired crushed CDF with 5% nZVI was able to remove approximately 90% of the initial 200 ?g/L As(III) in 30 minutes of contact time, while the fired crushed CDF only removed a few per cent As(III). Part of the faster As(III) removal of the unfired filter was a result of sorption by the clay, but the nZVI contributed considerably. Although, the LRVs for MS2 bacteriophages by fired filter material were higher in the batch experiment (LRV 0.42-1.52) than in the filter experiment – probably due more intensive contact - there was also no enhanced MS2 bacteriophage reduction noticed for the fired CDFs with nZVI compared to the fired blank CDF. There are probably several reactions that caused this loss of performance of ZVI. The results of the filter experiments indicated that there was insufficient surface contact with the nZVI particles; either due to unavailability of nZVI particles on the pore surface or due to too high flow rates. The addition of nZVI particles namely led to a considerable increase of flow rate, probably as a result of successive expansion and shrinking of the nZVI during firing. Furthermore, it is hypothesized that due to the vitrification process, in which the clay bonds together, the nZVI became enclosed in the clay structure. Furthermore, the 57Fe Mössbauer spectra evidenced that during firing all the added nZVI was oxidized into hematite, which probably affects the removal of arsenic. Different ZVI corrosion products have a different ability to adsorb arsenic: ZVI exhibits the greatest arsenic adsorption, secondly magnetite, then hematite and lastly goethite (Mamindy-Pajany et al. (2011)). This study showed that ZVI has potential for the removal of arsenic in HWTS, but with application in a different setting than by firing it in the CPF. Suggestions were made for potential alternatives: (i) CPFs with an iron coating; (ii) CPF with ZVI pre-treatment in the form of an hang-element or an extra bucket on top of the CPF, like the effective SONO filter for arsenic removal (Neumann et al., 2013); (iii) CPF with inside iron mixed ceramic pellets (Shafiquzzam et al.,2013). When designing a new type of CPF it is important to make sure that the iron (oxides) particles can be reached and that the flow rate is not too high, which ensures that the contact time with the iron (oxides) particles is long enough. Furthermore, additional research is needed on the enhancement of virus removal and inactivation. It is recommended to study the combination of nZVI and nAg in more detail and also to look at other combination of metals, such as Ag and copper. In order to better understand the adsorption of viruses onto different media it is advised to perform to determine the actual pHPZC of the used media. Lastly, it is advised that in a later stage of future research experiments should be performed with more challenging water and varying parameters such as the turbidity, the pH, competing ions, the ionic strength, influent arsenic concentration and different types of viruses.Sanitary EngineeringWater ManagementCivil Engineering and Geoscience
Authoring and management tools for adaptive educational hypermedia systems : the AHA! case study
No full textCreating and maintaining adaptive educational applications is hard work for teachers and developers. In order to help the author perform these tasks the e-learning systems must provide authoring and management tools. In this chapter we describe several useful tools for working with adaptive educational hypermedia systems, using the Adaptive Hypermedia Architecture (AHA!) system. AHA! is a well-known open source general-purpose adaptive hypermedia system. In the current AHA! distribution versions there are some general adaptive author tools as Concept Editor, Graph Editor, and Form Editor, all accessible through the overall Application Management Tool. There is also a specific educational tool: the Test Editor (and the associated Test Engine) and we are now developing some others such as a Course Editor and Mining tool. In this chapter we describe the AHA! system and the functionality of each of these authoring and management tools intended to help teachers and application developers
Sediment concentrations and Sediment transport in case of Irregular breaking waves
No full textCoastal changes occur mostly as a result of changes in sediment transport along the coast. If at cross-section A, the sediment transport is for any reason larger (or smaller) than at cross-section B, accretion (or erosion) will take place in between the two cross-sections. For prediction of coast-lines in the future, the prediction of the net sediment transport is therefore essential. Various models, such as that of Bijker, Van Rijn, Nielsen, Engelund & Hansen and Ackers & White are available to predict the sediment transport by knowledge of wave height and current strength. The reliability of these models is unknown because data under field conditions are scarce. Only few relations between sediment transport, current velocity and wave height are known. For these reasons a laboratory study was carried out to extend the knowledge of the basic phenomena in morphological processes. The study contains experiments in which sediment concentrations and fluid velocities have been measured in case of irregular breaking waves alone and in combination with a current. Chapter 2 deals with the sediment transport basics. Two types of sediment transport, the longshore and the cross-shore sediment transport are discussed and the objectives of the present experiments are presented. In Chapter 3 the experimental set up is described. The measured parameters, methods and instruments are discussed. The experimental programme of the series A and the series B I and B2 are presented. Chapter 4 covers the experimental results from test series A. The wave characteristics, fluid velocities and the influence of these parameters on the sediment concentration, sediment load and sediment transport are studied. Chapter 5 deals with the experimental results from test series B I and B2. The distribution of the sediment concentrations, fluid velocities, sediment loads and sediment transport rates over a sand bar are studied. In Chapter 6 a comparison is made between the measurements and the sediment transport models by Van Rijn and Bijker. Transport rates, concentration profiles and velocity profiles are compared. In Chapter 7 a list of conclusions and recommendations is presented.Hydraulic EngineeringCivil Engineering and Geoscience
Debt maturity and firm performance : a panel study of Indian companies
No full textEconomic policy makers traditionally hold the view that, because of imperfections in capital markets, a shortage of long-term finance acts as a barrier to industrial performance and growth. Long term finance is thought to allow firms to invest in more productive technologies, even when they do not produce immediate payoffs, without fear of premature liquidation. As a result, special state-supported term-lending institutions have been established, especially in developing countries. But some believe that short-term finance may offer better incentives because it allows suppliers of finance to monitor and control firms more effectively, thus improving the firms'performance. The authors empirically investigate the determinants and consequences of the term structure of debt. Using a rich panel of data on privately owned companies in India, they also examine the influence of debt maturity structures on those firm's performance, especially on productivity. The results are not conclusive, but seem to support conventional beliefs about the importance of long term finance to firm performance. Heavy leveraging, however, has a strong negative impact on productivity. They base their econometric evidence on estimates of a maturity equation and of a production function augmented by financial variables. The data on which these results are based have been generated by a financial system in which there is little competition, in which state-owned financial institutions are not guided by the profit motive and have no control over interest rates, so one cannot say whether short term finance would have been more beneficial in a less regulated system. Moreover, by the end of the 1980s, the capital base of India's government-owned financial institutions had been severely eroded and they carried a heavy burden of nonperforming assets. This means that the benefits of long term finance must be weighed against the costs.Banks&Banking Reform,Financial Intermediation,Economic Theory&Research,Municipal Financial Management,Environmental Economics&Policies
Arsenic removal in rapid sand filters
No full textArsenic (As) mobility in water is worldwide studied since its toxicity was proven in 1888. Intake of As can lead to skin disease, cancer, kidney and heart failure, diabetes and paralysis. In the Netherlands, groundwater used for drinking water production contains As in the range from 0 – 70 μg/L. Currently, all groundwater treatment plants reduce As in drinking water below the WHO standard of 10 μg/L. However, to ensure no adverse health effects occur by the intake of drinking water, Dutch drinking water companies investigate implications of distributing water with As concentrations below 1 μg/L. The new target value causes 58% of the treatment plants with measurable As in the raw water (19% of all total groundwater treatment plants) to need some sort of adjustment to their treatment scheme to comply with the new As target value...Sanitary Engineerin
A Novel D-Galacturonate Fermentation Pathway in Lactobacillus suebicus Links Initial Reactions of the Galacturonate-Isomerase Route With the Phosphoketolase Pathway
No full textD-galacturonate, a key constituent of pectin, is a ubiquitous monomer in plant biomass. Anaerobic, fermentative conversion of D-galacturonate is therefore relevant in natural environments as well as in microbial processes for microbial conversion of pectin-containing agricultural residues. In currently known microorganisms that anaerobically ferment D-galacturonate, its catabolism occurs via the galacturonate-isomerase pathway. Redox-cofactor balancing in this pathway strongly constrains the possible range of products generated from anaerobic D-galacturonate fermentation, resulting in acetate as the predominant organic fermentation product. To explore metabolic diversity of microbial D-galacturonate fermentation, anaerobic enrichment cultures were performed at pH 4. Anaerobic batch and chemostat cultures of a dominant Lactobacillus suebicus strain isolated from these enrichment cultures produced near-equimolar amounts of lactate and acetate from D-galacturonate. A combination of whole-genome sequence analysis, quantitative proteomics, enzyme activity assays in cell extracts, and in vitro product identification demonstrated that D-galacturonate metabolism in L. suebicus occurs via a novel pathway. In this pathway, mannonate generated by the initial reactions of the canonical isomerase pathway is converted to 6-phosphogluconate by two novel biochemical reactions, catalyzed by a mannonate kinase and a 6-phosphomannonate 2-epimerase. Further catabolism of 6-phosphogluconate then proceeds via known reactions of the phosphoketolase pathway. In contrast to the classical isomerase pathway for D-galacturonate catabolism, the novel pathway enables redox-cofactor-neutral conversion of D-galacturonate to ribulose-5-phosphate. While further research is required to identify the structural genes encoding the key enzymes for the novel pathway, its redox-cofactor coupling is highly interesting for metabolic engineering of microbial cell factories for conversion of pectin-containing feedstocks into added-value fermentation products such as ethanol or lactate. This study illustrates the potential of microbial enrichment cultivation to identify novel pathways for the conversion of environmentally and industrially relevant compounds.BT/Industriele MicrobiologieOLD BT/Cell Systems EngineeringBT/Environmental BiotechnologyBT/Biotechnologi
Corrigendum: Platinated Nucleotides are Substrates for the Human Mitochondrial Deoxynucleotide Carrier (DNC) and DNA Polymerase γ: Relevance for the Development of New Platinum-Based Drugs (ChemistrySelect, (2016), 1, (4633-4637), 10.1002/slct.201600961)
No full textIn agreement with all authors of this paper the order of the authors and the contribution “Paola Lunetti[+], Alessandro Romano[+], Chiara Carrisi, Daniela Antonucci, Tiziano Verri, Giuseppe E. De Benedetto, Vincenza Dolce, Francesco P. Fanizzi, Michele Benedetti,* and Loredana Capobianco.* [+] These authors contributed equally to this paper. * Corresponding authors: Michele Benedetti and Loredana Capobianco, Department of Biological and Environmental Sciences and Technologies, University of Salento, 73100 Lecce.” is corrected to read the original order of the first submitted version of the paper: “Chiara Carrisi[+], Alessandro Romano[+], Paola Lunetti, Daniela Antonucci, Tiziano Verri, Giuseppe E. De Benedetto, Vincenza Dolce, Francesco P. Fanizzi, Michele Benedetti,* and Loredana Capobianco.* [+] These authors contributed equally to this paper. * Corresponding authors: Loredana Capobianco and Michele Benedetti, Department of Biological and Environmental Sciences and Technologies, University of Salento, 73100 Lecce.” For completeness the following individual contributions of the authors were added in the Supporting Information: “Author contributions: L.C., M.B., C.C., A.R. designed research; C.C., A.R., P.L. and D.A. performed research; L.C., M.B., C.C., A.R., V.D. and P.L. analysed data; F.P.F., A.R., L.C. and M.B. wrote the paper; L.C., M.B., T.V., G.D.B. and F.P.F. active discussion paper revision.”
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