The Use of a Stably Expressed FRET Biosensor for Determining the Potency of Cancer Drugs

Many cancer drugs are intended to kill cancer cells by inducing apoptosis. However, the potency assays used for measuring the bioactivity of these products are generally cell viability assays which do not distinguish between cell death and growth inhibition. Here we describe a cell-based fluorescence resonance energy transfer (FRET) biosensor designed to measure the bioactivity of apoptosis inducing cancer drugs. The biosensor contains cyan fluorescent protein (CFP) linked via caspase 3 and caspase 8 specific cleavage recognition sequences to yellow fluorescent protein (YFP). Upon caspase activation, as in the case of apoptosis induction, the linker is cleaved abolishing the cellular FRET signal. This assay closely reflects the mechanism of action of cancer drugs, in killing cancer cells and therefore can function as a potency test for different cancer drugs. We rigorously demonstrate this through characterization of a class of proteins targeting the death receptors. The one-step assay appears to be superior to other apoptosis-based assays because of its simplicity, convenience, and robustness.     

抗生素效价测定实验的几点改进

抗生素效价测定是本科实验教学中常见的实验,但目前常用实验步骤复杂,影响实验结果的因素多,造成实验重复性不高。针对这一问题,参照有关文献从制备菌悬液、制备上层培养基菌层、抑菌圈打孔方法和抗生素加注几个方面进行改进。结果表明改进后的方法操作简便,重复性好,收到了良好的实验教学效果。     

Trichloroethylene Carcinogenic Potency

Mention of tradename, specific equipment, or proprietary product does not constitute a guarantee or warranty by the State of California or imply approval to the exclusion of other products. The conclusions reached herein represent those of the author and do not necessarily represent those of the State of California. Current U.S. regulatory policy regarding the carcinogenic potential of trichloroethylene (TCE) in humans is conflicting. Weight-of-evidence considerations show either no or inconsistent associations between chronic TCE exposure and excess human cancer risk. Occupational exposure limits are so great (538,000 µg/m³) that daily absorbed doses are greater than the rodent no observed adverse effect level (NOAEL). Using the regulatory strength-of-evidence approach, recommended ambient air concentration limits (1.1 µg/m³) are derived using the default linearized multistage model. The latter assumes a radiomimetic mode of action, a highly questionable assumption in light of published TCE mechanism of action data. Given the current state of U.S. regulatory policy on this material, credible analyses of the data are needed from neutral nongovernmental organizations.     

高效价冻干人用狂犬病疫苗暴露后免疫程序的研究

初步确定高效价冻干人用狂犬病疫苗（6．0IU／剂）暴露后免疫程序。制备高效价的冻干人用狂犬病疫苗（6．0IU／剂）,以狂犬病街毒CNX8601和BD06分别攻击小鼠和比格犬的咬肌,接种不同效价的狂犬病疫苗,以RFFIT法检测中和抗体,根据动物死亡情况,计算暴露后疫苗保护率,对不同效价的疫苗进行中和抗体测定和保护率统计分析。在以小鼠为实验动物的疫苗保护率研究中,冻干人用狂犬病疫苗（3．1IU／剂）0／3／7／14／28免疫程序的保护率为40．6％,高效价的冻干人用狂犬病疫苗（6．0IU／剂）0／3／14免疫程序的保护率为56．2％,中和抗体比较,P〈0．05,2组间有显著性差异;在以比格犬为实验动物的保护效果研究中,冻干人用狂犬病疫苗的保护率（3．1IU／剂）为70％;高效价的冻干人用狂犬病疫苗（6．0IU／剂）的保护率为80％,中和抗体的比较,P〉0．05,没有显著性差异。高效价冻干人用狂犬病疫苗暴露后免疫程序可初步确定为0、3、14d免疫。