Juvenile food limitation in standard tests: a warning to ecotoxicologists.

Standard ecotoxicological tests are as simple as possible and food sources are mainly chosen for practical reasons. Since some organisms change their food preferences during the life-cycle, they might be food limited at some stage if we do not account for such a switch. As organisms tend to respond more sensitively to toxicant exposure under food limitation, the interpretation of test results may then be biased. Using a reformulation of the von Bertalanffy model to analyze growth data of the pond snail Lymnaea stagnalis, we detected food limitation in the early juvenile phase. The snails were held under conditions proposed for a standardized test protocol, which prescribes lettuce as food source. Additional experiments showed that juveniles grow considerably faster when fed with fish flakes. The model is based on Dynamic Energy Budget (DEB) theory, which allows for mechanistic interpretation of toxic effects in terms of changes in energy allocation. In a simulation study with the DEB model, we compared the effects of three hypothetical toxicants in different feeding situations. The initial food limitation when fed with lettuce always intensified the effect of the toxicants. When fed with fish flakes, the predicted effect of the toxicants was less pronounced. From this study, we conclude that (i) the proposed test conditions for L. stagnalis are not optimal, and require further investigation, (ii) fish flakes are a better food source for juvenile pond snails than lettuce, (iii) analyzing data with a mechanistic modeling approach such as DEB allows identifying deviations from constant conditions, (iv) being unaware of food limitation in the laboratory can lead to an overestimation of toxicity in ecotoxicological tests. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s10646-012-0973-5) contains supplementary material, which is available to authorized users

Closing The Marketing Strategy Tactics-Gap: An Institutional Theory Analysis Of Pharmaceutical Value Chain

This chapter identifies a strategy-tactics gap in most previous studies of pharmaceutical marketing, and addresses it by systematically analyzing the marketing strategies used in practice with the help of a unique dataset of court discovery documents unsealed in a recent litigation. Adopting an institutional theory perspective, we examine the dominant logic that underlies pharmaceutical marketing strategies, and contrast it with the organizing logics of the value chain partners. Four distinct marketing strategies with carefully crafted interdependencies emerge from our analysis: (1) market penetration strategy involving a focus on segmentation and penetration, (2) evidence-based strategy involving production of science, (3) medical education strategy involving development and dissemination of standards of care, and (4) surrogate selling strategy involving leverage of peer-to-peer influence among target physicians. Together, the strategies uncovered in our analysis provide coherence to the observed marketing tactics and show that they are largely consistent with the logic of consequences which conflicts with the logic of appropriateness guiding the actions of the value chain partners. The institutional theory analysis shows that: (1) pharmaceutical value chain is characterized by conflicted logics, (2) that are amplified by pharmaceutical marketing strategies thereby, (3) inviting regulatory intervention to constrain and restrict pharmaceutical marketing efforts. We propose an open systems framework that elaborates on value chain interdependencies and compare it with the economic framework that characterizes most current research. We close the chapter with an agenda for future research into the theory and practice of pharmaceutical marketing