Case definitions for human poisonings postulated to palytoxins exposure.

A series of case reports and anecdotal references describe the adverse effects on human health ascribed to the marine toxin palytoxin (PLTX) after different exposure routes. They include poisonings after oral intake of contaminated seafood, but also inhalation and cutaneous/systemic exposures after direct contact with aerosolized seawater during Ostreopsis blooms and/or through maintaining aquaria containing cnidarian zoanthids. The symptoms commonly recorded during PLTX intoxication are general malaise and weakness, associated with myalgia, respiratory effects, impairment of the neuromuscular apparatus and abnormalities in cardiac function. Systemic symptoms are often recorded together with local damages whose intensity varies according to the route and length of exposure. Gastrointestinal malaise or respiratory distress is common for oral and inhalational exposure, respectively. In addition, irritant properties of PLTX probably account for the inflammatory reactions typical of cutaneous and inhalational contact. Unfortunately, the toxin identification and/or quantification are often incomplete or missing and cases of poisoning are indirectly ascribed to PLTXs, according only to symptoms, anamnesis and environmental/epidemiological investigations (i.e. zoanthid handling or ingestion of particular seafood). Based on the available literature, we suggest a "case definition of PLTX poisonings" according to the main exposure routes, and, we propose the main symptoms to be checked, as well as, hemato-clinical analysis to be carried out. We also suggest the performance of specific analyses both on biological specimens of patients, as well as, on the contaminated materials responsible for the poisoning. A standardized protocol for data collection could provide a more rapid and reliable diagnosis of palytoxin-poisoning, but also the collection of necessary data for the risk assessment for this family of toxins.

Metallothionein-like proteins in the freshwater oligochaete Limnodrilus udekemianus and their role as a homeostatic mechanism against cadmium toxicity.

The purpose of this study was to determine if metallothioneins are present in the aquatic oligochaete Limnodrilus udekemianus and to determine the interplay between the presence of these proteins, cadmium (Cd) exposure, and Cd toxicity. The latter was geared specifically towards evaluating the role of metallothionein as a homeostatic mechanism against Cd toxicity. These issues are important for evaluating the usefulness of the quantification of metallothioneins as a biomonitoring tool. Worms in sediment were exposed to Cd under static conditions, with Cd initially added to the aqueous phase. Survival was monitored while respiration (as a measure of sublethal Cd effects) was determined immediately following exposure. Metallothioneins were separated from the cytosol by gel permeation high performance liquid chromatography (HPLC) while Cd levels were quantified in whole worms, cytosol and cytosolic fractions. Also, a Cd-saturation assay was used to determine the amounts of Cd bound to metallothionein and the total Cd-binding capacity of the metallothionein. Limnodrilus udekemianus has a metallothionein-like protein (an inducible cytosolic protein with an apparent molecular weight of approximately 15 kD that binds high levels of Cd and shows a red shift upon Cd binding). Sediment Cd levels above 60 microg/g were lethal to the worms (in 8-day exposures). Respiration rates at 13 and 41 microg/g Cd were not significantly different from controls, though cytosolic Cd levels were substantially increased in the 41 microg/g exposure. In this latter cytosol, Cd levels were significantly elevated in the low molecular weight pool (which includes metallothioneins) but not in the other pools, while the Cd-saturation assay also showed that worms in this group had significantly elevated levels of metallothionein-bound Cd. However, in all treatments the metallothionein was far from saturated by Cd. These observations indicate that no 'spill-over' of Cd was evident as lethal levels of Cd were approached. The overall cytosolic Cd distribution, and the degree of metallothionein saturation in Limnodrilus udekemianus thus do not appear to be good predictors of Cd toxicity in this species.