To develop well defined in vitro cell system to test cytotoxicity of a number of model toxins, genetically engineered V79 Chinese hamster fibroblasts expressing isoenzymes of cytochrome P4501A1 XEM2 cells and V79 ce...To develop well defined in vitro cell system to test cytotoxicity of a number of model toxins, genetically engineered V79 Chinese hamster fibroblasts expressing isoenzymes of cytochrome P4501A1 XEM2 cells and V79 cells (parental), which lack cytochrome P450 enzyme activities, were used as controls. The cytotoxic effect of trans 7,8 dihydrbenzo(a)pyrene (BP 7,8 diol) on the parental cells V79 and V79 derived XEM2 cells were evaluated by two methods for cell viability. The data obtained expressed that BP 7,8 diol ranging from 1.0 μmol·L 1 to 5.0 μmol·L 1 in concentrations incubated for 24 h showed a strong cytotoxic effect in XEM2 cells (expressing rat cytochrome P4501A1) in a concentration dependent manner. Time dependent decrease for survival of XEM2 cells was also observed at 2.5 μmol·L 1 concentration. Likewise, BP 7,8 diol did not alter the survival of the parental cells V79 under the same condition. This study also showed that α naphthoflavone (αNF), a well known inhibitor of cytochrome P4501A1 might alter BP 7,8 diol induced cytotoxicity in the XEM2 cells. Our results suggested that cytochrome P4501A1 is responsible for BP 7, 8 diol induced cytotoxicity.展开更多
本文介绍了一种着眼于侵蚀-搬运-堆积链的因果关系及其类型,研究盆地沉积物搬运的区域性的分布系统方法。ETA(Erosion Transport Accumulation)系统可以根据其搬运营力(风、水、雪、冰、重力及人类活动)加以定义、制图与描述。根据要解...本文介绍了一种着眼于侵蚀-搬运-堆积链的因果关系及其类型,研究盆地沉积物搬运的区域性的分布系统方法。ETA(Erosion Transport Accumulation)系统可以根据其搬运营力(风、水、雪、冰、重力及人类活动)加以定义、制图与描述。根据要解决的实际问题与制图比例尺的不同,从源区到暂时性或永久性堆积区追踪沉积物,进而得出ETA系统时间和空间上的内在逻辑关系。该方法适用于任何时间和空间尺度。ETA系统可分为:1)活动休止的化石系统,称为古ETA系统;2)现在活动的系统,称为现代ETA系统;3)未来活动的系统,称为未来ETA系统。通过野外调查和遥感可以查明ETA过程产生的侵蚀、搬运和堆积特征。在一系列ETA系统图的基础上,就可以得出调控某一地区ETA系统的一套办法。根据野外详细调查,介绍了意大利北部Ampezzan白云岩地区(面积约200km^2)Boite河上游山间盆地的实例。展开更多
文摘To develop well defined in vitro cell system to test cytotoxicity of a number of model toxins, genetically engineered V79 Chinese hamster fibroblasts expressing isoenzymes of cytochrome P4501A1 XEM2 cells and V79 cells (parental), which lack cytochrome P450 enzyme activities, were used as controls. The cytotoxic effect of trans 7,8 dihydrbenzo(a)pyrene (BP 7,8 diol) on the parental cells V79 and V79 derived XEM2 cells were evaluated by two methods for cell viability. The data obtained expressed that BP 7,8 diol ranging from 1.0 μmol·L 1 to 5.0 μmol·L 1 in concentrations incubated for 24 h showed a strong cytotoxic effect in XEM2 cells (expressing rat cytochrome P4501A1) in a concentration dependent manner. Time dependent decrease for survival of XEM2 cells was also observed at 2.5 μmol·L 1 concentration. Likewise, BP 7,8 diol did not alter the survival of the parental cells V79 under the same condition. This study also showed that α naphthoflavone (αNF), a well known inhibitor of cytochrome P4501A1 might alter BP 7,8 diol induced cytotoxicity in the XEM2 cells. Our results suggested that cytochrome P4501A1 is responsible for BP 7, 8 diol induced cytotoxicity.
文摘本文介绍了一种着眼于侵蚀-搬运-堆积链的因果关系及其类型,研究盆地沉积物搬运的区域性的分布系统方法。ETA(Erosion Transport Accumulation)系统可以根据其搬运营力(风、水、雪、冰、重力及人类活动)加以定义、制图与描述。根据要解决的实际问题与制图比例尺的不同,从源区到暂时性或永久性堆积区追踪沉积物,进而得出ETA系统时间和空间上的内在逻辑关系。该方法适用于任何时间和空间尺度。ETA系统可分为:1)活动休止的化石系统,称为古ETA系统;2)现在活动的系统,称为现代ETA系统;3)未来活动的系统,称为未来ETA系统。通过野外调查和遥感可以查明ETA过程产生的侵蚀、搬运和堆积特征。在一系列ETA系统图的基础上,就可以得出调控某一地区ETA系统的一套办法。根据野外详细调查,介绍了意大利北部Ampezzan白云岩地区(面积约200km^2)Boite河上游山间盆地的实例。