Technological innovation has helped the zebrafish embryo gain ground as a disease model and an assay system for drug screening. Here, we review the use of zebrafish embryos and early larvae in... Show moreTechnological innovation has helped the zebrafish embryo gain ground as a disease model and an assay system for drug screening. Here, we review the use of zebrafish embryos and early larvae in applied biomedical research, using selected cases. We look at the use of zebrafish embryos as disease models, taking fetal alcohol syndrome and tuberculosis as examples. We discuss advances in imaging, in culture techniques (including microfluidics), and in drug delivery (including new techniques for the robotic injection of compounds into the egg). The use of zebrafish embryos in early stages of drug safety-screening is discussed. So too are the new behavioral assays that are being adapted from rodent research for use in zebrafish embryos, and which may become relevant in validating the effects of neuroactive compounds such as anxiolytics and antidepressants. Readouts, such as morphological screening and cardiac function, are examined. There are several drawbacks in the zebrafish model. One is its very rapid development, which means that screening with zebrafish is analogous to __screening on a run-away train.__ Therefore, we argue that zebrafish embryos need to be precisely staged when used in acute assays, so as to ensure a consistent window of developmental exposure. We believe that zebrafish embryo screens can be used in the pre-regulatory phases of drug development, although more validation studies are needed to overcome industry scepticism. Finally, the zebrafish poses no challenge to the position of rodent models: it is complementary to them, especially in early stages of drug research. Show less
In a surveillance study in Jakarta, Indonesia, 88 typhoid and 26 paratyphoid fever patients were identified by blood culture. Risk factors for transmission of typhoid fever were mainly intra... Show moreIn a surveillance study in Jakarta, Indonesia, 88 typhoid and 26 paratyphoid fever patients were identified by blood culture. Risk factors for transmission of typhoid fever were mainly intra-household factors (poor hand-washing hygiene, recent household contacts), whereas paratyphoid was mainly contracted through street food. In an additional study, street vendors observed poorer hand-washing and food-handling hygiene compared to food handlers in restaurants, and had higher bacterial loads in dishwater. Further host factor-studies in (para)typhoid patients revealed that polymorphisms in genes encoding pro-inflammatory cytokines (IFN-_, IL1A/B, IL1R1, TNFRSF1A, CASP1 and CRP) were not associated with susceptibility to typhoid fever, and might therefore at most be associated with severity of disease. An association was found of typhoid fever and a polymorphism in the PARK2/PACRG proteasome-mediated protein degradation pathway through ubiquitination, similar to infection with Mycobacterium leprae. Also an association between genotypes in the Cystic Fibrosis Transmembrane Conductance Regulator (the affected protein in Cystic Fibrosis) and susceptibility to typhoid fever was found, suggesting a decreased adherence potential of S. typhi to intestinal mucosal cells with these polymorphisms. Finally, bacterial characteristics were compared by use of AFLP and biochemical/antibiotic susceptibility profiles, showing very homogeneous S. typhi and S. paratyphi A strains circulating in the study area. Show less
