A strategy to discover new organizers identifies a putative heart organizer

Organizers are regions of the embryo that can both induce new fates and impart pattern on other regions. So far, surprisingly few organizers have been discovered, considering the number of patterned tissue types generated during development. This may be because their discovery has relied on transplantation and ablation experiments. Here we describe a new approach, using chick embryos, to discover organizers based on a common gene expression signature, and use it to uncover the anterior intestinal portal (AIP) endoderm as a putative heart organizer. We show that the AIP can induce cardiac identity from non-cardiac mesoderm and that it can pattern this by specifying ventricular and suppressing atrial regional identity. We also uncover some of the signals responsible. The method holds promise as a tool to discover other novel organizers acting during development

Helicobacter pylori prevalence in endoscopy and medical staff

The epidemiology and mode of transmission of Helicobacter pylori is currently unclear; it is postulated that the human stomach is the natural reservoir and that spread occurs by faecal-oral or oral-oral transmission. The aim of this study was to assess the prevalence of H. pylori in gastroenterologists and gastroenterology nurses compared with internists, general nurses and the normal population. An enzyme-linked immunosorbent assay technique (sensitivity 96%, specificity 88%) was used to detect circulating H. pylori immunoglobulin G antibodies in 39 gastroenterologists, 107 gastroenterology nurses, 25 internists and 42 general nurses. These subjects were compared to an age- and sex-matched Caucasian population obtained by random sampling of an urban population area. The overall prevalence of H. pylori in gastroenterologists was 69% compared to 40% of internists (P < 0.01), 17% of gastroenterology nurses (P < 0.001), 19% of general nurses (P < 0.01) and 32% of controls (P < 0.01). There was no significant difference in H. pylori prevalence between the gastroenterology nurses and controls, general nurses and controls. The prevalence in gastroenterologists increased with years of practice to levels greater than age-matched controls. The prevalence in gastroenterology nurses increased with age and years of working and was similar to age-matched control subjects. These findings of an increased prevalence of H. pylori infection in gastroenterologists performing endoscopy support human-to-human transmission possibly from patients to medical staff

Representing people, representing nature, representing the world.

Problems of representation lie at the centre of recent experiments in deliberative democracy. The problems are not primarily social scientific questions concerning the statistical representiveness of small-scale deliberative institutions but normative questions about their political and ethical legitimacy. Experiments in deliberative democracy often rely for their representative legitimacy on appeals to the presence of members of different groups. However, they often do so without clear sources of authorisation and accountability from those represented. The representation of nonhumans and future generations in deliberative institutions is still more problematic. In the necessary absence of their authorisation, accountability, and presence, claims to speak on their behalf relies on epistemic claims, coupled with care. To highlight these problems is not to claim that small deliberative institutions are illegitimate but rather to point out the need for a clearer account of their role in democratic institutions and the proper sources of contestability of their outcomes