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Abstract: Envenomation syndromes induced by Atlantic cnidaria have been tabulated and their therapy discussed. The pharmacokinetics of the venom has been emphasized. Pain occurs instantly and reaches a zenith rapidly in the surf. The nematocysts have already penetrated the dermis and disease proceeds before help can arrive. This fact plus the relative impermeability of human epidermis hampers the efficacy of topical agents. Oral analgesics, the agents of choice, are seldom offered and systemic administration of these drugs is usually not necessary. The use of hot or cold applications has not been settled. Measures to inactivate nematocysts within tentacles adherent to skin post-sting have been demonstrated in vitro, but the clinical significance of these actions has not been shown. Using an abrader (sand, crystalline papain) to counter-irritate nearby skin might provide relief. Antivenoms for Atlantic cnidaria are not available. The instances when verapamil might be employed are very rare. The reasons for the increasing case load of these injuries are discussed and the need to discover more effective therapeutic agents is emphasized. [Copyright &y& Elsevier]

Abstract: A separation of toxic components from the upside down jellyfish Cassiopea xamachana (Cx) was carried out to study their cytotoxic effects and examine whether these effects are combined with a binding activity to cell membrane receptors. Nematocysts containing toxins were isolated from the autolysed tentacles, ruptured by sonication, and the crude venom (CxTX) was separated from the pellets by ultracentrifugation. For identifying its bioactive components, CxTX was fractionated by gel filtration chromatography into six fractions (named fraction I–VI). The toxicity of CxTX and fractions was tested on mice; however, the hemolytic activity was tested on saline washed human erythrocytes. The LD50 of CxTX was 0.75μg/g of mouse body and for fraction III, IV and VI were 0.28, 0.25 and 0.12μg/g, respectively. Fractions I, II and V were not lethal at doses equivalent to LD50 1μg/g. The hemolytic and phospholipase A2 (PLA2) activities of most fractions were well correlated with their mice toxicity. However, fraction VI, which contains the low molecular mass protein components (≤10kDa), has shown no PLA2 activity but highest toxicity to mice, highest hemolytic activity, and bound significantly to the acetylcholine muscarinic receptors (mAChRs) isolated from rat brain. The results suggested that fraction VI contains proteinaceous components contributing to most of cytolysis as well as membrane binding events. Meanwhile, fraction IV has shown high PLA2 that may contribute to the venom lethality and paralytic effects. [Copyright &y& Elsevier]

Chrysaora quinquecirrha (sea nettle) nematocyst venom is lethal to rainbow killifish (Adina xenica) when injected intraperitoneally or topically applied to the exposed brain or denuded epithelium. The lethal activity is thermostable requiring 100°C heat for inactivation. This paper reports here for the first time that the venom also activates the complement system with the subsequent formation of the C5b-9 terminal complement complex. The events are associated with both a strong chemoattractant release and the tissue damage. These are also, at least in part, responsible for the pathogenesis of some clinical signs and symptoms associated to the jellyfish stings. [Copyright &y& Elsevier]