ABSTRACT
OBJECTIVE: The aim of this study is to measure the knowledge regarding the new sanitation water system being implemented in Dessources, a rural community in the municipality of Croix-des-Bouquets in Haiti after a two-year intervention programme. DESIGN AND METHODS: A cross-sectional epidemiologic design was used to measure the knowledge of the people in the community using a semi-structured questionnaire. Data collection followed a face-to-face interview process in all houses of the community. The instrument content validity was performed by a panel of experts followed by Cronbach's alpha test to establish the reliability of knowledge scale. In addition, association measures were done using Stata 11.0 statistical package. RESULTS: Content validity test were performed with minimum changes and an alpha of 0.74 was obtained for the scale. Response rate was 65.57% (41/60 houses); non-participants were only those who did not meet the inclusion criteria. Most of the participants (77.5%) were 21-49 years old and 85% had been living in the community for more than 20 years. Bivariate analysis showed that the people of Dessources had adequate knowledge. Significant differences, however, were found among the zones that are not in use of the new sanitary systems and among families with more than seven members per house. CONCLUSIONS: Differences found can be explained based on the Rogers theoretical diffusion of innovation model. The evaluation shows that people of Dessources in Haiti have a high knowledge regarding the new water sanitation system and provided evidence of an adequate health education programme intervention.
ABSTRACT
BCF2, a monoclonal antibody raised against scorpion toxin Cn2, is capable of neutralizing both, the toxin and the whole venom of the Mexican scorpion Centruroides noxius Hoffmann. The single chain antibody fragment (scFv) of BCF2 was constructed and expressed in Escherichia coli. Although its affinity for the Cn2 toxin was shown to be in the nanomolar range, it was non-neutralizing in vivo due to a low stability. In order to recover the neutralizing capacity, the scFv of BCF2 was evolved by error-prone PCR and the variants were panned by phage display. Seven improved mutants were isolated from three different libraries. One of these mutants, called G5 with one mutation at CDR1 and another at CDR2 of the light chain, showed an increased affinity to Cn2, as compared to the parental scFv. A second mutant, called B7 with a single change at framework 2 of heavy chain, also had a higher affinity. Mutants G5 and B7 were also improved in their stability but they were unable to neutralize the toxin. Finally, we constructed a variant containing the changes present in G5 and B7. The purpose of this construction was to combine the increments in affinity and stability borne by these mutants. The result was a triple mutant capable of neutralizing the Cn2 toxin. This variant showed the best affinity constant (KD=7.5x10(-11) M), as determined by surface plasmon resonance (BIAcore). The k(on) and k(off) were improved threefold and fivefold, respectively, leading to 15-fold affinity improvement. Functional stability determinations by ELISA in the presence of different concentrations of guanidinium hydrochloride (Gdn-HCl) revealed that the triple mutant is significantly more stable than the parental scFv. These results suggest that not only improving the affinity but also the stability of our scFv were important for recovering its neutralization capacity. These findings pave the way for the generation of recombinant neutralizing antisera against scorpion stings based on scFvs.
Subject(s)
Antibodies, Monoclonal/immunology , Antibodies, Monoclonal/metabolism , Antivenins/metabolism , Immunoglobulin Fragments/immunology , Mutation/genetics , Scorpion Venoms/immunology , Amino Acid Sequence , Animals , Antibodies, Monoclonal/genetics , Antibody Affinity , Antivenins/genetics , Antivenins/immunology , Biological Evolution , Cloning, Molecular , Epitope Mapping , Escherichia coli/metabolism , Molecular Sequence Data , Neutralization Tests , Peptide Fragments/genetics , Peptide Fragments/immunology , Peptide Library , Peptides/isolation & purification , Substrate SpecificityABSTRACT
Hemoglobin is able to oxidize polycyclic aromatic hydrocarbons, PAH's, in presence of hydrogen peroxide. Among 12 aromatic compounds tested, six were oxidized; anthracene, carbazole, dibenzothiophene, fluorene, 9-hexylanthracene and pyrene. The products were identified as aromatic ketones and sulfoxides. Effect of organic solvent concentration and hemoglobin stability were determined.
