Derivation of a chronic reference dose for perfluorohexane sulfonate (PFHxS) for reproductive toxicity in mice.

Perfluorohexane sulfonate (PFHxS) is a six-carbon perfluoroalkyl sulfonic acid that was used as an industrial surfactant, but is now found as an environmental contaminant worldwide. In addition to its use as an industrial surfactant, it is a legacy contaminant from the use of aqueous film-forming foams. Despite its widespread occurrence in the environment and evidence of biological activity associated with PFHxS and similar perfluoroalkyl sulfonic acids in rodents, there is no oral toxicity value currently available from the IRIS Database. To derive an oral reference dose (RfD) for PFHxS, available toxicity studies were reviewed using a weight-of-evidence approach. A 42-day mouse reproductive study was chosen as the critical study for the derivation of the oral RfD. Benchmark dose modeling was utilized to derive a point of departure (POD) for a reduction in litter size. A 95% lower confidence limit on the benchmark dose (BMDL) of 13,900 ng/mL (serum PFHxS) was modeled for a reduction in litter size. An oral RfD for PFHxS of 4.0 ng/kg/d was calculated by conversion of the BMDL to a human equivalent oral dose using a human half-life adjusted dosimetric conversion factor and the application of a total uncertainty factor of 300. Additional research is needed to better characterize the toxicity associated with oral exposure to PFHxS and refine the development of toxicity values.

Metabolome analysis of gram-positive bacteria such as Staphylococcus aureus by GC-MS and LC-MS.

The field of metabolomics has become increasingly important in the context of functional genomics. Together with other "omics" data, the investigation of the metabolome is an essential part of systems biology. Beside the analysis of human and animal biofluids, the investigation of the microbial physiology by methods of metabolomics has gained increased attention. For example, the analysis of metabolic processes during growth or virulence factor expression is crucially important to understand pathogenesis of bacteria. Common bioanalytical techniques for metabolome analysis include liquid and gas chromatographic methods coupled to mass spectrometry (LC-MS and GC-MS) and spectroscopic approaches such as NMR. In order to achieve metabolome data representing the physiological status of a microorganism, well-verified protocols for sampling and analysis are necessary. This chapter presents a detailed protocol for metabolome analysis of the Gram-positive bacterium Staphylococcus aureus. A detailed manual for cell sampling and metabolite extraction is given, followed by the description of the analytical procedures GC-MS and LC-MS. The advantages and limitations of each experimental setup are discussed. Here, a guideline specified for S. aureus metabolomics and information for important protocol steps are presented, to avoid common pitfalls in microbial metabolome analysis.

[Studies on flavianic acids as color reference standard for thin-layer chromatography].

Various flavianic acids were prepared and examined for the preparation for color reference standard for thin-layer chromatography (TLC). Their analytical data were: IR spetra, their specific absorptions were same; no impurities were detected; specific odor-free. It was clear that the prepared flavianic acids were useable as color reference standards for TLC.

Variable mutagenic activity of commercial preparations of ABTS (2,2'-azino-di(3-ethyl-benz-thiazoline) sulphonic acid.

Different batches of ABTS obtained from the same commercial source varied in their capacity to effect direct mutation in the strains of Salmonella typhimurium used routinely in the incorporation test of Ames. One batch, obtained in 1976, and another obtained early in 1979, both exhibited direct base-pair substitution and frame-shift activities. These activities, however, were absent from each of two batches obtained after 1979, and also from a highly purified preparation from a different source. The possible presence of the unsulphonated immediate precursor of ABTS as a mutagenic impurity is an unlikely explanation for the activity of the mutagenic preparations. It is more probable that the commercial synthesis generated other, mutagenic, impurities which remained in the batches obtained in 1976 and early in 1979, but were absent or were removed from later batches. The identity of these active impurities is unknown. Pure ABTS is neither a direct nor an indirect mutagen.

The international reference preparation of colistin methane sulfonate.

The international unit of colistin methane sulfonate has been defined by collaborative assay as the activity contained in 0.00007874 mg of the international reference preparation. The definition was based on results from 7 laboratories in 5 countries which carried out assays against their existing national standards. Because of the complex heterogeneity in composition of this antibiotic the international reference preparation was not designated as an international standard.