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A random-walk simulation of microdialysis is used to examine how a reaction that consumes analyte in the medium external to the probe affects the extraction and recovery processes. The simulations suggest that such a reaction can promote the extraction process while simultaneously inhibiting the recovery process, which appears to be consistent with recent experimental evidence of asymmetry in the extraction and recovery of the neurotransmitter, dopamine, during brain microdialysis. This suggests that quantitative microdialysis strategies that rely on the extraction fraction as a measure of the probe recovery value, such as the no-net-flux method, will produce an underestimate of the analyte concentration in the external medium when that analyte is consumed by a reaction in the external medium. Furthermore, if experimental conditions arise under which the kinetics of the reaction are changed, then changes in the extraction and recovery processes are likely to occur as well. The implications of these theoretical findings for the quantitative interpretation of in vivo microdialysis results obtained for the neurotransmitter dopamine are examined.

Zinc dialkyldithiophosphates (ZDDPs) are one of the most common anti-wear additives present in commercially-available motor oils. The ZDDP concentrations of motor oils are most commonly determined using inductively coupled plasma atomic emission spectroscopy (ICP-AES). As part of an undergraduate research project, we have determined the Zn concentrations of eight commercially-available motor oils and one oil additive using neutron activation analysis (NAA), which has potential for greater accuracy and less sensitivity to matrix effects as compared to ICP-AES. The 31 P nuclear magnetic resonance ( 31 P-NMR) spectra were also obtained for several oil additive samples which have been heated to various temperatures in order to study the thermal decomposition of ZDDPs.

Albendazole chemotherapy of larval Echinococcus multilocularis was studied in the Mongolian jird by administration of medicated feed at various concentrations and durations. The effects were evaluated by comparison of treated and control groups in terms of host mortality, larval metastases to the lungs, and final weight and histologic appearance of larval tissue. Viability of larval tissue at necropsy of each animal was tested by inoculation into two noninfected jirds. Albendazole-medicated feed (0.05%-0.10%) significantly inhibited larval growth. Other effects of the drug included larval degeneration and necrosis, inhibition of protoscolex formation, decreased pulmonary metastases, and reduced mortality of hosts. Adverse effects on the parasite correlated significantly with serum albendazole metabolite levels and duration of therapy. However, serum albendazole levels in jirds equal to or exceeding concentrations achieved in humans receiving daily doses of 10 mg/kg of body weight did not kill the parasite.

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