Effects of tamoxifen on volume-activated Cl- currents of nasopharyngeal carcinoma cells at different stages of the cell cycle     

LUO Hai-bing  WANG Li-wei  MAO Jian-wen  JIAO Cheng-gang  FAN Ai-hui  NIE Si-huai  LI Pan  CHEN Li-xin 《园艺学报》2007,23(2):226-230

AIM:To investigate the inhibitory effects of Cl- channel blocker, tamoxifen, on volume-activated Cl- currents of nasopharyngeal carcinoma cells (CNE-2Z cells) in G₁ and S phases. METHODS:Highly synchronous cells in G₁ phase and S phase were obtained by the serum starvation and the double-block techniques. The whole-cell patch clamp technique was used to observe the effects of tamoxifen on volume-activated Cl- currents and to analyze the anion permeability of volume-activated Cl- channels. RESULTS:47% hypotonic stimulation activated a Cl- current in the nasopharngeal carcinoma cells at the cell cycle stage G₁ phase and S phase. Tamoxifen at concentration of 10 to 30 μmol/L completely inhibited the current. However, the time needed to completely inhibit the current was dose-dependent and was different between G₁ phase and S phase. The time needed to completely inhibit the current was shorter in G₁ cells than that in S phase cells. The anion permeability sequence of the volume-activated Cl- channel was I->Cl->gluconate in both G₁ phase and S phase cells. The permeability of G₁ phase cells to I- was higher than that in S phase cells, but to gluconate was lower than that in S phase cells. CONCLUSIONS:The density of the volume-activated Cl- current, the anion permeability of the channel and the sensitivity of the current to tamoxifen were different between the CNE-2Z cells in G₁ phase and those in S phase. The results suggest that the expression of tamoxifen-sensitive, volume-activated chloride channels is differentiated at different stages of the cell cycle.  相似文献   

Inhibitory effect of ATP on proliferative signaling in immortalized human fibroblasts     

LI Jun-wu 《园艺学报》2001,17(4):337-339

AIM: To investigate the inhibitory effects of ATP on proliferation signaling in immortalized human fibroblasts. METHODS: Immortalized human fibroblasts were treated with ATP, ATP conbined with calcium or potassium channel antagonists, respectively. The intracelluar-free calcium ([Ca²⁺]i), inositol 1,4,5-trisphosphate(IP₃) levels and cell viability were detected at different time points. RESULTS: ATP significantly increased the [Ca²⁺]i and decreased the IP₃ level in immortalized human fibroblasts, especially at initial stage (P＜0.01) . Compared to ATP alone, the proliferation rates remarkably increased when calcium or potassium channel antagonists were used (P＜0.01, respectively) with ATP. CONCLUSION: The calcium and potassium channels and IP₃ involved in the inhibitory effects of ATP on the proliferative signaling in immortalized human fibroblasts.  相似文献   

论制造商网络营销与传统营销渠道冲突的管理策略     

古永红 《四川畜牧兽医学院学报》2006,4(4):52-54

随着电子商务的发展，网络营销渠道已成为或正成为许多制造商的营销渠道。由于渠道成员之间存在目标冲突、领域冲突及理解冲突，网络营销渠道与传统营销渠道问的冲突不可避免。文中提出要根据产品和服务本身的特点，结合电子商务环境的状况，动态地、发展地管理网络营销和传统营销间的渠道冲突，以达到增强企业竞争力的目的。  相似文献   

梯级水电站水量平衡的研究   总被引：1，自引：1，他引：1  

齐鄂荣  罗昌 《中国农村水利水电》2003,(10):10-13

针对三个梯级水电站出现的水量计算不平衡的现象，通过对这三个水电站的日常水情调度数据的分析和对库区河段的明渠非恒定流计算，探讨了水量计算不平衡的原因，并给出了这些水电站的水位流量关系特性，对其他流域梯级水电站有一定参考作用。  相似文献   

泾河中上游流域土地利用格局变化与驱动因子分析   总被引：12，自引：3，他引：12  

张希彪 《水土保持学报》2005,19(6):137-140,152

利用RS和GIS技术和景观生态学的方法，对泾河中上游流域1986～2000年的景观特征及其动态变化进行了研究。通过计算多样性指数、优势度、破碎化指数、分离度等指标，进行了土地利用格局变化分析，并对该区域土地利用变化的主导因子进行了分析，认为该区土地利用／土地覆被变化的驱动力主要为：自然因素、经济因素、人口压力及宏观政策等，并互相影响、互相制约，共同影响流域景观格局的变化。  相似文献   

Modelling C and N mineralisation in soil food webs during secondary succession on ex-arable land     

Remko Holtkamp  Annemieke van der Wal  Wim H. van der Putten  Peter C. de Ruiter  Stefan C. Dekker 《Soil biology & biochemistry》2011,43(2):251-260

  相似文献   

Role of K⁺ channels in attenuation of pulmonary vasoreactivity following chronic hypobaric hypoxia in rats     

HONG Zhi-gang  WANG Di-xun  HU Qing-hua  CHEN Qi-ling  SUN Bing-yong 《园艺学报》2001,17(10):960-963

AIM and METHODS: To determine the role of different K⁺-channels in attenuation of vasoreactivity of intrapulminary artery rings induced by chronic hypoxia. RESULTS: ①Acute hypoxia-induced pulmonary vasoconstriction (HPV) could be significantly attenuated by chronic hypobaric hypoxia for 15 days and for 30 days. ②HPV could be significantly potentiated by ATP-sensitive K⁺-channel (K_ATP) blocker or Ca²⁺-activated K⁺-channel (K_Ca) blocker, and the potentiated scope in chronic hypoxic group was much higher than that observed in control group. ③Delayed rectifier K⁺-channel (K_DR) blocker showed no effect on HPV in both control group and chronic hypoxic group. CONCLUSION: Both K_ATP and K_Ca play an important modulating role in HPV and its potentiation may be a critical mechanism for the attenuated vasoreactivity to acute hypoxia following chronic hypobaric hypoxia.  相似文献   

清水作用下全动床复式河槽河床演变特性     

杨克君;聂锐华;刘兴年 《排灌机械》2013,(11):954-957,963

通过水槽试验,探讨了清水作用下由非均匀沙构筑而成的全动床复式河槽的演变特性,包括河床完全粗化后河道稳定宽度及滩岸侵蚀的沿程变化.复式河槽断面构筑而成后,实施倒灌,然后恢复地形,最后用全站仪施测初始河道地形,在试验结束后,相应断面再做精细床面形态测量.复式河槽流量由槽首的矩形堰量测,水位由自动水位仪量测.试验结果表明,随着泥沙淤积量的增大,主槽水深变浅;而河道水深变浅,又将会使床面泥沙起动的作用力减小,河道水深将变得更浅.清水作用下的全动床复式河槽达到稳定时,河道稳定宽度将沿程变化;河道完全粗化后,主槽宽度增大,滩岸侵蚀速率在空间上变化趋势表现为越往下游,滩岸侵蚀速度越小;在清水作用下,河道滩岸发生侵蚀,其侵蚀面积有沿程减小的趋势,这与流速沿程的变化相一致.  相似文献   

数值积分法计算抛物线形渠道恒定渐变流水面线   总被引：2，自引：2，他引：0  

文辉  李风玲 《农业工程学报》2014,30(24):82-86

针对目前差分试算法、迭代法及图解法求解水面线存在着计算过程繁复、误差较大的问题,该文通过对抛物线断面渠道恒定渐变流水面线微分方程进行恒等变形,并对引入的特征水深与特征湿周的关系进行分析及计算,重点考察工程实际中常用的特征水深范围为0.6~1.5 m的抛物线形断面渠道,依据最小二乘法进行回归分析将方程中的特征湿周由不可积函数替代为可积分的幂函数,实现了由有限差分逐一断面推算到数值积分法的直接求解。与现有方法相比,该抛物线形断面渠道恒定渐变流水面线简化计算公式具有工作效率明显提高、精度好的特点。实例计算及误差分析表明:在工程实用范围内(特征水深范围0.6~1.5 m)该公式最大相对误差仅为0.17%,对生产实践具有实用推广意义。  相似文献   

Extending Our Reach: Surveying,Analyzing, and Planning Outreach to Extension Staff     

Kristen Leigh Mastel 《Journal Of Agricultural & Food Information》2014,15(4):268-281

This study describes how University of Minnesota Extension staff locate and use information to accomplish daily activities. The major findings were: (a) information seeking is a daily or weekly need; (b) staff use predominately online resources from a variety of sources—peer-reviewed journals, technical or research reports, and government information—and use search engines most frequently to locate them; and (c) Extension staff are aware of the majority of library resources and services. Extension staff welcome advanced information-seeking tools and techniques for professional development.  相似文献