RESUMEN
Toxin synergism is a complex biochemical phenomenon, where different animal venom proteins interact either directly or indirectly to potentiate toxicity to a level that is above the sum of the toxicities of the individual toxins. This provides the animals possessing venoms with synergistically enhanced toxicity with a metabolic advantage, since less venom is needed to inflict potent toxic effects in prey and predators. Among the toxins that are known for interacting synergistically are cytotoxins from snake venoms, phospholipases A2 from snake and bee venoms, and melittin from bee venom. These toxins may derive a synergistically enhanced toxicity via formation of toxin complexes by hetero-oligomerization. Using a human keratinocyte assay mimicking human epidermis in vitro, we demonstrate and quantify the level of synergistically enhanced toxicity for 12 cytotoxin/melittin-PLA2 combinations using toxins from elapids, vipers, and bees. Moreover, by utilizing an interaction-based assay and by including a wealth of information obtained via a thorough literature review, we speculate and propose a mechanistic model for how toxin synergism in relation to cytotoxicity may be mediated by cytotoxin/melittin and PLA2 complex formation.
RESUMEN
Typical government nutrition programmes usually lack precise information on the size of groups that could benefit from interventions, on the different types of potential beneficiaries and their location, and on socio-economic and cultural characteristics through which they could readily be identified. In the functional classification approach to the definition of nutritional problems, detailed information on human behaviour and social constraints is collected at family and community levels. The data are then interpreted in general terms in order to understand how these factors contribute to inadequate levels of nutrition within larger groups. This new approach should enable more effective measures for reducing the numbers of those living under conditions of deprivation to be presented to planners and decision makers.