Objective To assess the reproducibility of brain activation by functional MR imaging during electroacupuncture stimulation at PC6(neiguan).Methods Six healthy adult volunteers participated in three identical scan sessions during different interval time.Each scan session consists of two functional tasks,an electroacupuncture stimulation(2 Hz) at PC6 and a control task of simple finger tapping.The reproducibility of brain responses was analyzed in terms of the overlap ratio of active volume within sessions and the ICC of active signal intensity in ROIs.Results The Roverlap of the simple finger tapping task(34.24?9.49) was significantly higher than that of the electroacupuncture stimulation task(13.23?14.21).The range of ICC of ROIs in the simple finger tapping task(0.69-0.80) was significantly higher than that of the electroacupuncture stimulation task(0.18-0.68).The results above showed that the reliability of brain activation in the finger tapping task group was higher than that in the electroacupuncture stimulation task group.The active intensity of ROIs in the simple finger tapping task was significantly higher than that in the electroacupuncture stimulation task,indicating the signal to noise ratio of brain activation in the finger tapping task group was higher than that in the electroacupuncture stimulation task group.Conclusion In contrast to the relatively reliable activation evoked by the simple finger tapping task,the activation evoked by electroacupuncture stimulation task was much more variable.The main possible reason is that the relatively low signal to noise ratio of brain activation on fMRI and low sensitivity caused the lower reproducibility of electroacupuncture stimulation task.The group analysis in combination with the individual functional data may be utilized to improve the reproducibility of fMRI evoked by electroacupuncture stimulation at PC6(neiguan).

A simple and rapid liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was de-veloped and validated for simultaneous determination of acetaminophen and oxycodone in human plasma. Acetaminophen-d4 and oxycodone-d3 were used as internal standards. The challenge en-countered in the method development that the high plasma concentration level of acetaminophen made the MS response saturated while the desired lower limit of quantification (LLOQ) for oxycodone was hard to reach was well solved. The analytes were extracted by protein precipitation using acetonitrile. The matrix effect of the analytes was avoided by chromatographic separation using a hydrophilic C18 column coupled with gradient elution. Multiple reaction monitoring in positive ion mode was performed on tandem mass spectrometer employing electrospray ion source. The calibration curves were linear over the concentration ranges of 40.0–8000 ng/mL and 0.200–40.0 ng/mL for acetaminophen and oxycodone, respectively. This method, which could contribute to high throughput analysis and better clinical drug monitoring, was successfully applied to a pharmacokinetic study in healthy Chinese volunteers.