401 research outputs found

    Putting Civilians First. NGO Perceptions and Expectations of UN Peacekeeping

    Get PDF
    NGOs and UN peacekeeping operations increasingly operate in a shared domain. NGOs commonly rely – at least partly – on UN peacekeepers for access and security, but they also express concerns about this. Yet remarkably little is known about what are their main concerns and how widespread they are. Even more importantly, what can be done to address them? This FBA Brief, written by members of one of the FBA’s research working groups, examines the answers to those questions

    Delivery of a functional anti-trypanosome Nanobody in different tsetse fly tissues via a bacterial symbiont, Sodalis glossinidius

    Get PDF
    Background: Sodalis glossinidius, a vertically transmitted microbial symbiont of the tsetse fly, is currently considered as a potential delivery system for anti-trypanosomal components that reduce or eliminate the capability of the tsetse fly host to transmit parasitic trypanosomes, an approach also known as paratransgenesis. An essential step in developing paratransgenic tsetse is the stable colonization of adult flies and their progeny with recombinant Sodalis bacteria, expressing trypanocidal effector molecules in tissues where the parasite resides. Results: In this study, Sodalis was tested for its ability to deliver functional anti-trypanosome nanobodies (Nbs) in Glossina morsitans morsitans. We characterized the in vitro and in vivo stability of recombinant Sodalis (recSodalis) expressing a potent trypanolytic nanobody, i.e. Nb_An46. We show that recSodalis is competitive with WT Sodalis in in vivo conditions and that tsetse flies transiently cleared of their endogenous WT Sodalis population can be successfully repopulated with recSodalis at high densities. In addition, vertical transmission to the offspring was observed. Finally, we demonstrated that recSodalis expressed significant levels (ng range) of functional Nb_An46 in different tsetse fly tissues, including the midgut where an important developmental stage of the trypanosome parasite occurs. Conclusions: We demonstrated the proof-of-concept that the Sodalis symbiont can be genetically engineered to express and release significant amounts of functional anti-trypanosome Nbs in different tissues of the tsetse fly. The application of this innovative concept of using pathogen-targeting nanobodies delivered by insect symbiotic bacteria could be extended to other vector-pathogen systems

    Paternal transmission of a secondary symbiont during mating in the viviparous tsetse fly

    Get PDF
    Sodalis glossinidius, a maternally inherited secondary symbiont of the tsetse fly, is a bacterium in the early/intermediate state of the transition toward symbiosis, representing an important model for investigating establishment and evolution of insect-bacteria symbiosis. The absence of phylogenetic congruence in tsetse-Sodalis coevolution and the existence of Sodalis genotypic diversity in field flies are suggestive for a horizontal transmission route. However, to date no natural mechanism for the horizontal transfer of this symbiont has been identified. Using novel methodologies for the stable fluorescent-labeling and introduction of modified Sodalis in tsetse flies, we unambiguously show that male-borne Sodalis is 1) horizontally transferred to females during mating and 2) subsequently vertically transmitted to the progeny, that is, paternal transmission. This mixed mode of transmission has major consequences regarding Sodalis' genome evolution as it can lead to coinfections creating opportunities for lateral gene transfer which in turn could affect the interaction with the tsetse host

    Expression and extracellular release of a functional anti-trypanosome Nanobody® in Sodalis glossinidius, a bacterial symbiont of the tsetse fly

    Get PDF
    <p>Abstract</p> <p>Background</p> <p><it>Sodalis glossinidius</it>, a gram-negative bacterial endosymbiont of the tsetse fly, has been proposed as a potential <it>in vivo </it>drug delivery vehicle to control trypanosome parasite development in the fly, an approach known as paratransgenesis. Despite this interest of <it>S. glossinidius </it>as a paratransgenic platform organism in tsetse flies, few potential effector molecules have been identified so far and to date none of these molecules have been successfully expressed in this bacterium.</p> <p>Results</p> <p>In this study, <it>S. glossinidius </it>was transformed to express a single domain antibody, (Nanobody<sup>®</sup>) Nb_An33, that efficiently targets conserved cryptic epitopes of the variant surface glycoprotein (VSG) of the parasite <it>Trypanosoma brucei</it>. Next, we analyzed the capability of two predicted secretion signals to direct the extracellular delivery of significant levels of active Nb_An33. We show that the pelB leader peptide was successful in directing the export of fully functional Nb_An33 to the periplasm of <it>S. glossinidius </it>resulting in significant levels of extracellular release. Finally, <it>S. glossinidius </it>expressing pelBNb_An33 exhibited no significant reduction in terms of fitness, determined by <it>in vitro </it>growth kinetics, compared to the wild-type strain.</p> <p>Conclusions</p> <p>These data are the first demonstration of the expression and extracellular release of functional trypanosome-interfering Nanobodies<sup>® </sup>in <it>S. glossinidius</it>. Furthermore, <it>Sodalis </it>strains that efficiently released the effector protein were not affected in their growth, suggesting that they may be competitive with endogenous microbiota in the midgut environment of the tsetse fly. Collectively, these data reinforce the notion for the potential of <it>S. glossinidius </it>to be developed into a paratransgenic platform organism.</p

    Training of Driving-Related Attentional Performance After Stroke Using a Driving Simulator

    Get PDF
    The objective of this study was to determine the effect of simulatorbased driving training on attentional performance after stroke. A further analysis of data was conducted from a randomized controlled trial in which the effect of simulator training and cognitive paper and pencil training to improve driving were compared. Performance in divided attention tasks before, during and after 15 hours of simulator-based training of general driving skills in 33 experimental participants were evaluated. Performance in divided attention tasks was assessed during navigation of a 5-km scenario with the divided attention tasks as the only event to respond to and another 13.5-km scenario that contained a good mixture of regular day to day traffic situations. There were significant improvements in mean response time to the divided attention tasks and time to complete the 5-km scenario. Significant decrease in mean response time, number of missed responses, collisions, pedestrians hit, total faults and run time and increase in number of correct responses were found in the 13.5-km scenario. Further analyses showed most improvements in the simulator assessments occurred between preand mid-training. Simulator-based training of driving skills positively impacted attentional performance. Findings in this study suggest that 10 hours of simulatorbased driving training after stroke is sufficient to realize meaningful benefits

    Concreteness and emotional valence ratings of 399 Dutch nouns

    Get PDF
    Copyright 1998 Psychologica Belgica. Published version of the paper reproduced here with permission from the publisher
    • …
    corecore