6320 research outputs found
Sort by
How to develop a theory-driven evaluation design - Lessons learned from an adolescent sexual and reproductive health programme in West Africa
No full textBACKGROUND: This paper presents the development of a study design modelled on the principles of theory-driven evaluation. It was used to evaluate an adolescent sexual and reproductive health intervention in Mali, Burkina Faso and Cameroon to improve continuity of care through the creation of networks of social and health care providers. Methods /design: Based on our experience and the existing literature, we developed a six-step framework for the design of theory -driven evaluations, which we applied in the ex-post evaluation of the networking component of the intervention. The protocol was drafted with the input of the intervention designers. The programme theory, the central element of theory-driven evaluation, was constructed on the basis of semi-structured interviews with designers, implementers and beneficiaries and an analysis of the intervention's logical framework. DISCUSSION: The six-step framework proved useful as it allowed for a systematic development of the protocol. We describe the challenges at each step. We found that there is little practical guidance in the existing literature, and also a mix up of terminology of theory-driven evaluation approaches. There is a need for empirical methodological development in order to refine the tools to be used in theory driven evaluation. We conclude that ex-post evaluations of programmes can be based on such an approach if the required information on context and mechanisms is collected during the programm
Impact of armed conflicts on urban livestock production in Brazzaville, Republic of Congo
No full textBrucellosis and tuberculosis in Arsi-Negele district, Ethiopia: prevalence in ruminants and people's behavior towards zoonoses
No full textApplying the principles of AIDS 'exceptionality' to global health: challenges for global health governance
No full text
Multi-scale environmental analysis and prediction for insects vector of disease; application to malaria vectors of Southeast Asia
No full text
Development of harmonised schemes for the monitoring and reporting of Echinococcus in animals and foodstuffs in the European Union
No full textIdentification of a tsetse fly salivary protein with dual inhibitory action on human platelet aggregation
No full textBACKGROUND: Tsetse flies (Glossina sp.), the African trypanosome vectors, rely on anti-hemostatic compounds for efficient blood feeding. Despite their medical importance, very few salivary proteins have been characterized and functionally annotated. METHODOLOGY/PRINCIPAL FINDINGS: Here we report on the functional characterisation of a 5'nucleotidase-related (5'Nuc) saliva protein of the tsetse fly Glossina morsitans morsitans. This protein is encoded by a 1668 bp cDNA corresponding at the genomic level with a single-copy 4 kb gene that is exclusively transcribed in the tsetse salivary gland tissue. The encoded 5'Nuc protein is a soluble 65 kDa glycosylated compound of tsetse saliva with a dual anti-hemostatic action that relies on its combined apyrase activity and fibrinogen receptor (GPIIb/IIIa) antagonistic properties. Experimental evidence is based on the biochemical and functional characterization of recombinant protein and on the successful silencing of the 5'nuc translation in the salivary gland by RNA interference (RNAi). Refolding of a 5'Nuc/SUMO-fusion protein yielded an active apyrase enzyme with K(m) and V(max) values of 43+/-4 microM and 684+/-49 nmol Pi/min xmg for ATPase and 49+/-11 microM and 177+/-37 nmol Pi/min xmg for the ADPase activity. In addition, recombinant 5'Nuc was found to bind to GPIIb/IIIa with an apparent K(D) of 92+/-25 nM. Consistent with these features, 5'Nuc potently inhibited ADP-induced thrombocyte aggregation and even caused disaggregation of ADP-triggered human platelets. The importance of 5'Nuc for the tsetse fly hematophagy was further illustrated by specific RNAi that reduced the anti-thrombotic activities in saliva by approximately 50% resulting in a disturbed blood feeding process. CONCLUSIONS/SIGNIFICANCE: These data show that this 5'nucleotidase-related apyrase exhibits GPIIb/IIIa antagonistic properties and represents a key thromboregulatory compound of tsetse fly saliva