Detection and Isolation of Emetic Bacillus cereus Toxin Cereulide by Reversed Phase Chromatography

The emetic toxin cereulide is a 1.2 kDa dodecadepsipeptide produced by the food pathogen Bacillus cereus. As cereulide poses a serious health risk to humans, sensitive and specific detection, as well as toxin purification and quantification, methods are of utmost importance. Recently, a stable isotope dilution assay tandem mass spectrometry (SIDA–MS/MS)-based method has been described, and an method for the quantitation of cereulide in foods was established by the International Organization for Standardization (ISO). However, although this SIDA–MS/MS method is highly accurate, the sophisticated high-end MS equipment required for such measurements limits the method’s suitability for microbiological and molecular research. Thus, we aimed to develop a method for cereulide toxin detection and isolation using equipment commonly available in microbiological and biochemical research laboratories. Reproducible detection and relative quantification of cereulide was achieved, employing reversed phase chromatography (RPC). Chromatographic signals were cross validated by ultraperformance liquid chromatography–mass spectrometry (UPLC–MS/MS). The specificity of the RPC method was tested using a test panel of strains that included non-emetic representatives of the B. cereus group, emetic B. cereus strains, and cereulide-deficient isogenic mutants. In summary, the new method represents a robust, economical, and easily accessible research tool that complements existing diagnostics for the detection and quantification of cereulide.     

股骨头缺血性坏死表面置换术的初步疗效观察

目的　评价表面置换术治疗股骨头缺血性坏死的临床效果。方法　应用自行研制的股骨头表面假体 ,对 6例FicatⅢ期和早Ⅳ期的股骨头缺血性坏死患者的 9髋进行了手术 ,并随访观察。结果　随访 6～ 2 0个月 ,采用Merled’Aubigne评分法评价疗效 ,评分由术前平均 6分改善至术后 16 .5分。 结论　股骨头表面置换术是治疗FicatⅢ期和早Ⅳ期股骨头缺血性坏死的较好方法 ,近期效果满意 ,远期效果有待继续观察     

Is Best–Worst Scaling Suitable for Health State Valuation? A Comparison with Discrete Choice Experiments

Health utility indices (HUIs) are widely used in economic evaluation. The best–worst scaling (BWS) method is being used to value dimensions of HUIs. However, little is known about the properties of this method. This paper investigates the validity of the BWS method to develop HUI, comparing it to another ordinal valuation method, the discrete choice experiment (DCE). Using a parametric approach, we find a low level of concordance between the two methods, with evidence of preference reversals. BWS responses are subject to decision biases, with significant effects on individuals' preferences. Non parametric tests indicate that BWS data has lower stability, monotonicity and continuity compared to DCE data, suggesting that the BWS provides lower quality data. As a consequence, for both theoretical and technical reasons, practitioners should be cautious both about using the BWS method to measure health‐related preferences, and using HUI based on BWS data. Given existing evidence, it seems that the DCE method is a better method, at least because its limitations (and measurement properties) have been extensively researched. Copyright © 2016 John Wiley & Sons, Ltd.