This proof-of-concept study used solid-phase microextraction fibers (SPME) to collect headspace vapors from a methicillin sensitive Staphylococcus aureus (MSSA) and a methicillin-resistant Staphylococcus aureus (MRSA) strain grown in vitro in liquid growth medium. The collected molecules were separated and identified using gas chromatography and mass spectrometry (GC/MS). Preliminary results distinguished these two strains and provide a foundation for a biomarker library that could one day serve as a diagnostic tool for identifying specific bacterial infections.
We evaluated performance characteristics of a semiautomated radioassay system (ARIA II, Becton Dickinson Immunodiagnostics) for simultaneous measurements of vitamin B12 and folic acid in serum. The system requires off-line boiling of samples, which are then processed on-line. The automated process includes dispensing of boiled samples, tracers, and binders (purified intrinsic factor and milk binder); incubation, separation of bound and free ligands; elution; counting radioactivity of 57Co and 125I; and data reduction. Results were compared with those obtained by a manual method (Diagnostic Products Corp.). Although the nonspecific binding of the ARIA II is more than double that of the manual system, the precision values are comparable (within- and between-assay CVs are less than 8.5%). Values obtained with these two systems correlated well except that folic acid concentrations obtained with ARIA II tended to be lower at high folic acid concentrations. We observed no significant total carryover or drift in the semiautomated system.
Two groups of workers occupationally exposed to glycol ethers in a varnish production plant or the ceramic industry were examined. For 19 persons the external and internal exposure was assessed on the Monday and Tuesday after an exposure-free weekend. In the varnish production area the concentrations of 2-ethoxyethanol (EE), 2-ethoxyethyl acetate (EEAc), and 2-butoxyethanol (BE) in air averaged 2.9, 0.5, and 0.5 ppm, respectively, on the Monday, and 2.1, 0.1, and 0.6 ppm, respectively, on the Tuesday. At the same workplaces the mean urinary 2-ethoxyacetic acid (EAA) and 2-butoxyacetic acid (BAA) concentrations were 53.2 and 0.2 mg/l on Monday preshift and 53.8 and 16.4 mg/l on Tuesday postshift. The results show that glycol ethers are very well absorbed through the skin. Therefore biological monitoring is indispensable. To study the kinetics of the toxic metabolite, 17 persons were examined for their excretion of EAA in urine during an exposure-free weekend. The median values of the calculated half-times were 57.4 and 63.4 h, respectively, which are longer than the values presented in literature until now. According to our calculations the limit value should not exceed 50 mg EAA per liter of urine, which is the current German biological tolerance value (BAT value) for EAA in urine. The maximum concentration value at the workplace (MAK value) for EE and EEAc in air should be revised. Finally, the subjects from the varnish production plant as well as a group of reference persons were studied for cytogenetic effects of glycol ethers (sister chromatid exchange, micronucleus test). Such effects could not be detected.
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