Research on modeling and simulation of the system of position transformation mechanical ventilation / 中国医疗器械杂志

The principle of Position Transformation Mechanical Ventilation (PTMV) was introduced briefly, and the mechanical structure and the intelligent control algorithm were studied. According to the principle and function requirement of PTMV, the mechanical structure of slip pole driven rocking chair(SPDRC) was proposed, the dynamics model of SPDRC was established, and the auto disturbance rejection controller was designed. The integrated model of control system was structured by using ADAMS and MATLAB, and the model validation and simulation were implemented. The simulation results indicate that the mechanical structure is feasible and the control process of ADRC is precise and steady.

Determination of the activity of cytochrome P-450 CYP2A6 by HPLC method with caffeine as metabolizing probe / 药学学报

<p><b>AIM</b>To establish a HPLC method for determining five major metabolites of caffeine in the urine, 5-acetylamino-6-formylamino-3-methyluracil (AFMU), 1-methylxanthine (1X), 1-methyluric acid (1U), 1,7-dimethyluric acid (17U) and 1,7-dimethylxanthine (17X) and assess the activity of cytochrome P-450 CYP2A6.</p><p><b>METHODS</b>The contents of five major metabolites of caffeine in the urine were determined by RP-HPLC method. Frequency distribution histogram was drawn by calculating the 17U/(AFMU + 1X + 1U + 17X + 17U) and then evaluated the activity of CYP2A6.</p><p><b>RESULTS</b>The frequency distribution histograms of CYP2A6 approximately indicated three distinct groups, the cut of point is 0.23 between fast metabolizer and intermediate type. And the cut of point is 0.15 between slow metabolizer and intermediate type.</p><p><b>CONCLUSION</b>The method is simple and rapid, suitable for the determination of metabolites of caffeine in urine. The method can be used to assay the activity of CYP2A6.</p>