Development of an inhalation physiologically based pharmacokinetic (PBPK) model for 2,2, 4-trimethylpentane (TMP) in male Long-Evans rats using gas uptake experiments

2,2,4-Trimethylpentane (TMP) is a volatile colorless liquid used primarily to increase the octane rating of combustible fuels. TMP is released in the environment through the manufacture, use, and disposal of products associated with the gasoline and petroleum industry. Short-term inhalation exposure to TMP (<?4?h;?>?1000?ppm) caused sensory and motor irritations in rats and mice. Like many volatile hydrocarbons, acute exposure to TMP may also be expected to alter neurological functions. To estimate in vivo metabolic kinetics of TMP and to predict its target tissue dosimetry during inhalation exposures, a physiologically based pharmacokinetic (PBPK) model was developed for the chemical in Long-Evans male rats using closed-chamber gas-uptake experiments. Gas-uptake experiments were conducted in which rats (80–90 days old) were exposed to targeted initial TMP concentrations of 50, 100, 500, and 1000?ppm. The model consisted of compartments for the closed uptake chamber, lung, fat, kidney, liver, brain, and rapidly and slowly perfused tissues. Physiological parameters were obtained from literature. Partition coefficients for the model were experimentally determined for air/blood, fat, liver, kidney, muscle, and brain using vial equilibration methods. Common to other hydrocarbons, metabolism of TMP via oxidative reactions is assumed to mainly occur in the liver. The PBPK model simulations of the closed chamber data were used to estimate in vivo metabolic parameters for TMP in male Long-Evans rats.     

气相色谱法测定达比加群酯中10种溶剂的残留

目的：建立气相色谱法检测达比加群酯中10种残留溶剂。方法：以Rtx-1（60 m×0.32 mm×1.0μm）极性毛细管柱程序升温,以氮气为载气,FID 为检测器,进样口温度为 200℃,检测器温度为 250℃,对达比加群酯中 10种残留溶剂（甲醇、乙醇、乙酸乙酯、丙酮、二氯甲烷、正己烷、四氢呋喃、异辛烷、吡啶和甲苯）进行测定。结果：各残留溶剂组分均能被良好分离,各溶剂线性关系良好,精密度 RSD 均不超过 3.50%,平均回收率为 96.0%~105.0%。结论：本文建立的方法可用于达比加群酯中残留溶剂的测定。     

青霉素酰胺酶在AOT／异辛烷反胶团中的稳定性研究

通过将青霉素酰胺酶包埋于ＡＯＴ／异辛烷反胶团中，对其稳定性进行了研究。结果表明，经反胶团包埋后，青霉素酰胺酶的热稳定性和ＰＨ稳定性较水相酶有所提高；该酶的热失活动力学特性表明，在５０℃下保温９０ｍｉｎ后酶有保留７５％左右。