Vibrio parahaemolyticus is a marine bacterium known to be a common cause of seafood gastroenteritis worldwide. The thermostable direct hemolysin (TDH) has been proposed to be a major virulence factor of V. parahaemolyticus. TDH causes intestinal fluid secretion as well as cytotoxicity in a variety of cell types. In this study, we investigated the interplay between the hemolysin's enterotoxic and cytotoxic effects by using both human and rat cell monolayers. As revealed by microspectrofluorimetry, the toxin causes a dose-dependent increase in intracellular free calcium in both Caco-2 and IEC-6 cells. This effect was reversible only when low toxin concentrations were tested. The TDH-activated ion influx pathway is not selective for calcium but admits ions such sodium and manganese as well. Furthermore, in the same range of concentration, the hemolysin triggers a calcium-dependent chloride secretion. At high concentrations, TDH induces a dose-dependent but calcium-independent cell death as assessed by functional, biochemical, and morphological assays.Vibrio parahaemolyticus is the leading cause of gastroenteritis due to the consumption of seafoods worldwide. Although this microorganism persists as a health hazard in the Far East, where it was originally isolated (20), it has also been reported either as a source of human disease or as an environmental contaminant along the North American, African, and Mediterranean coasts (2, 4, 7). Although V. parahaemolyticus most often induces a self-limiting, watery diarrhea, it occasionally causes bloody diarrhea and, rarely, sudden cardiac arythmia (12). A protein secreted by V. parahaemolyticus, known as thermostable direct hemolysin (TDH), has received considerable attention in past decades as the main pathogenic factor. Although originally studied for its hemolytic property, TDH has been long suspected to be an enterotoxin involved in most cases of V. parahaemolyticus diarrhea. Additionally, an epidemiological role was also attributed to Trh, a TDH-related hemolysin (3,13,18). The link between TDH and secretory diarrhea was first demonstrated by Nishibuchi and coworkers (22), who, combining molecular genetics with an in vitro rabbit model, showed that only those strains expressing the TDHencoding gene are able to induce intestinal chloride secretion. Using the same animal model, our group then found that TDH is one of the few enterotoxins produced by a human pathogen whose action is mediated by intracellular calcium (24). We later showed that TDH also raises the cytosolic free calcium concentration ([Ca 2ϩ ] i ) in nontransformed rat intestinal IEC-6 cells (5). TDH has also cardiotoxic (11) and cytotoxic (25) effects; the latter, in particular, have been only partially characterized.In this in vitro study, we examined the interplay between the cytotoxicity of TDH and the toxin's capacity to induce fluid secretion, in view of the pathophysiological significance of such a link. We used both transformed and nontransformed cell lines in order to identify true epithelial alte...

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At the end of the century, Europe showed a considerable variation in both delivery of PPC and training for doctors who care for children. This study identified 3 different health care delivery systems for PPC, as well as 2 types of pediatricians who work in community-based settings. Formal training in PPC or CP for both pediatricians and general practitioners varied from established curricula to no teaching at all. Economic and sociopolitical issues, professional power, and geographical and historical factors may explain the differences in pediatric care among European countries.