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Human red blood cell acetylcholinesterase (RBC-AChE) activity is valuable for detecting potential exposure to cholinesterase inhibiting substances (CIS). A reliable population-based RBC-AChE activity reference range is critical for early and massive clinical and occupational toxicology screening. Previous published studies were often limited to small numbers of subjects, various testing methods, and crude statistical data analyses. We tested 4818 adult subjects with a well-established 17-minute modified Michel method over a 2-year period. We conducted a retrospective data analysis and systematically investigated on the influences to testing values from gender, age, age group, and their combinations and interactions. No significant difference was observed in the testing values between males (mean, medium, interquartile range = 0.76, 0.76, 0.71–0.80 ΔpH/h, respectively) and females (mean, medium, interquartile range = 0.76, 0.76, 0.71–0.81 ΔpH/hour, respectively), when gender was the only factor considered (p = 0.7238). However, with age progression, male testing values exhibited a consistent upward trend, while females did not show any clear patterns. Linear regression analysis of the data revealed that gender, age, and age group more or less affected testing values either as independent variables or with their combinations and interactions. However, more potential factors need to be included to achieve better testing value predictions. We recommend the toxicological testing community to adopt a new set of age group specific RBC-AChE activity reference ranges for males (0.68–0.80, 0.69–0.81, 0.70–0.83, 0.71–0.84, and 0.73–0.87 ΔpH/h for 18–29, 30–39, 40–49, 50–59, and ≥60 years old, respectively) while keeping the current reference range (0.63–0.89 ΔpH/hour) for females. [ABSTRACT FROM AUTHOR]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2005.04.009 Byline: Madeleine Beekman, Robert L. Fathke, Thomas D. Seeley Abstract: When a honeybee swarm lifts off to fly to a new nest site, only the scouts know in what direction the swarm must fly, and they constitute only about 5% of the bees in a swarm. Nevertheless, a swarm will fly quickly and directly to its destination. How does the small minority of informed scouts indicate the swarm's flight direction to the large majority of uninformed bees? Two hypotheses have been suggested. The first proposes that the flying scouts streak through the swarm cloud in the direction of the goal, thereby indicating the travel direction visually (vision hypothesis). The second proposes that flying scouts release pheromones from their Nasanov glands at the front of the cloud of flying bees, thereby indicating the travel direction chemically (olfaction hypothesis). We tested both hypotheses by studying the flights of normal swarms and comparing them to the flights of swarms composed of bees whose Nasanov glands were sealed shut. Our results support the vision hypothesis and contradict the olfaction hypothesis. We identified fast-flying bees ('streakers') in swarms, as predicted by the vision hypothesis, but we found no effect of sealing the Nasanov glands of swarming bees. Sealed-bee swarms were perfectly capable of flying directly to a new nest site. Author Affiliation: (*) School of Biological Sciences, University of Sydney, Australia (a ) Department of Neurobiology and Behavior, Cornell University, U.S.A. Article History: Received 2 December 2004; Revised 20 January 2005; Accepted 4 April 2005 Article Note: (miscellaneous) MS. number: 8369