Microhabitat use by rodent species in a central Brazilian cerrado

We analysed microhabitat use by the rodents Calomys tener, Necromys lasiurus and Thalpomys lasiotis and the factors that may influence their abundances in “murundu” grasslands (open fields with termite mounds) at Aguas Emendadas Ecological Station, Planaltina, Federal District, Brazil. Two grids with 100 sampling points were established and traps were placed at each intersection of the grid, where five microhabitat variables were also measured. Rodents were trapped from June through October 2008. Microhabitat explained 21% of the variation in community structure, with grass density and the number of termite mounds explaining most of the variation. Necromys lasiurus was most often captured in areas with dense grasses, whereas T. lasiotis and C. tener were most often in areas less dense with grasses.     

Gas chromatographic determination of methamphetamine and its metabolite amphetamine in human plasma and urine following conversion to N-propyl derivatives

A gas chromatographic method for the simultaneous determination of methamphetamine and its metabolite amphetamine in human plasma and urine is described. The method utilizes reductive alkylation with propionaldehyde and sodium borohydride to produce N-propyl derivatives, which have excellent chromatographic properties. Structural analogs of the analytes, p-methylmethamphetamine and p-methylamphetamine, are used as internal standards. The method has good precision and accuracy for concentrations ranging from less than 10 ng/ml to 5000 ng/ml and has been used to measure plasma concentrations as part of a pharmacokinetic/pharmacodynamic study of methamphetamine in humans.