1,066 research outputs found

    In vitro micropropagation of white dasheen (Colocassia esculenta)

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    Plant regeneration for efficient vegetative propagation in white dasheen has been developed. Meristem cultured on Murashige and Skoog medium supplemented with 6-Benzyladenine (BA) and Indole-3-aceticacid (IAA) gave the best explants establishment and development. This in vitro system provides for a uniform production system which is easily managed and yields high quality cornels for commercial production

    Sublimation Pressures of Refractory Fluorides

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    Vapor species identification, absolute vapor pressures and heats of sublimation of refractory metal fluoride

    Investment and Abandonment Decisions in the Presence of Imperfect Aggregation of Information

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    The traditional marshallian rule of investing when the value of the investment is greater than its installment cost is modified in the presence of irreversibility and uncertainty, giving rise to an option component. Additionally, the interaction of participants holding each one a right to invest can give rise under imperfect information to situations of deviations from the optimal timing of exercise of the investment and to herd behavior or informational cascades given that the agents take into account when deciding not only their private set of information but also the information released to the market by the decisions made by the other agents. In the present paper we develop a model that tries to capture these effects and dynamics by showing revision of conditional expectations of the agents, and with considerations regarding the degree of dispersion of information in the economy and the effect of the number of participants and their effect into their behavior

    Alternative pre-analytic sample handling techniques for glucose measurement in the absence of fluoride tubes in low resource settings.

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    INTRODUCTION: Sodium fluoride (NaF) tubes are the recommended tubes for glucose measurements, but these are expensive, have limited number of uses, and are not always available in low resource settings. Alternative sample handling techniques are thus needed. We compared glucose stability in samples collected in various tubes exposed to different pre-analytical conditions in Uganda. METHODS: Random (non-fasted) blood samples were drawn from nine healthy participants into NaF, Ethylenediaminetetraacetic acid (EDTA), and plain serum tubes. The samples were kept un-centrifuged or centrifuged with plasma or serum pipetted into aliquots, placed in cool box with ice or at room temperature and were stored in a permanent freezer after 0, 2, 6, 12 and 24 hours post blood draw before glucose analysis. RESULTS: Rapid decline in glucose concentrations was observed when compared to baseline in serum (declined to 64%) and EDTA-plasma (declined to 77%) after 6 hours when samples were un-centrifuged at room temperature whilst NaF-plasma was stable after 24 hours in the same condition. Un-centrifuged EDTA-plasma kept on ice was stable for up to 6 hours but serum was not stable (degraded to 92%) in the same conditions. Early centrifugation prevented glucose decline even at room temperature regardless of the primary tube used with serum, EDTA-plasma and NaF-plasma after 24 hours. CONCLUSION: In low resource settings we recommend use of EDTA tubes placed in cool box with ice and analysed within 6 hours as an alternative to NaF tubes. Alternatively, immediate separation of blood with manual hand centrifuges will allow any tube to be used even in remote settings with no electricity

    Monoclonal Antibodies to Meningococcal Factor H Binding Protein with Overlapping Epitopes and Discordant Functional Activity

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    Background: Meningococcal factor H binding protein (fHbp) is a promising vaccine candidate. Anti-fHbp antibodies can bind to meningococci and elicit complement-mediated bactericidal activity directly. The antibodies also can block binding of the human complement down-regulator, factor H (fH). Without bound fH, the organism would be expected to have increased susceptibility to bacteriolysis. Here we describe bactericidal activity of two anti-fHbp mAbs with overlapping epitopes in relation to their different effects on fH binding and bactericidal activity. Methods and Principal Findings: Both mAbs recognized prevalent fHbp sequence variants in variant group 1. Using yeast display and site-specific mutagenesis, binding of one of the mAbs (JAR 1, IgG3) to fHbp was eliminated by a single amino acid substitution, R204A, and was decreased by K143A but not by R204H or D142A. The JAR 1 epitope overlapped that of previously described mAb (mAb502, IgG2a) whose binding to fHbp was eliminated by R204A or R204H substitutions, and was decreased by D142A but not by K143A. Although JAR 1 and mAb502 appeared to have overlapping epitopes, only JAR 1 inhibited binding of fH to fHbp and had human complement-mediated bactericidal activity. mAb502 enhanced fH binding and lacked human complement-mediated bactericidal activity. To control for confounding effects of different mouse IgG subclasses on complement activation, we created chimeric mAbs in which the mouse mAb502 or JAR 1 paratopes were paired with human IgG1 constant regions. While both chimeric mAbs showed similar binding to fHbp, only JAR 1, whic
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