硅胶柱与凝胶柱净化/气相色谱-质谱联用测定植物叶片中多环芳烃

建立了索氏提取-硅胶柱和凝胶柱净化/气相色谱-质谱联用(GC-MS)测定植物叶片中多环芳烃的分析方法。叶片中的多环芳烃经二氯甲烷-正己烷(体积比1∶1)索氏提取,提取液采用硅胶柱和凝胶柱两步净化(手填硅胶柱和GPC柱)后,进行GC-MS测定,根据保留时间和特征离子进行定性,内标法定量。方法检出限为0.025 1~5.80 ng/g,加标回收率为82.2%~130%,相对标准偏差不大于11%。该方法能有效去除植物叶片中的色素与油脂,适用于植物叶片中多组分多环芳烃的痕量分析,为测定植物组织内多环芳烃的含量提供了技术支撑。     

离子与通道相互作用对NaK 通道通透特性影响的研究

以NaK 通道的三维精细结构为基础,从理论上阐述了NaK 通道对钠离子、钾离子、铷离子以及钙离子的通透机理,钡离子可以作为NaK 通道阻断剂的微观机理,我们的研究结果表明,通道与离子的相互作用是决定通道对不同离子选择性的基础, 反映通道与离子相互作用的位能曲线是通道对不同离子通透性的外在表现. 关键词： NaK 通道 密度泛函 布朗动力学 通透性     

Properties of Hydrated Alkali Metals Aimed at the Ion Channel Selectivity

The hydration structure properties of different alkali metal ions with eight water molecules and potassium ions with different numbers of water molecules are studied using the mixed density functional theory, B3LYP, with 6-3110 basis set. The hydration structures are obtained from structure optimization and the optimum numbers of water molecules in the innermost hydration shell for the alkali metal ions are found. Some useful information about the ion channel selectivity is presented.     

K+离子通道及其研究进展

 细胞是通过细胞膜与外界隔离的,在细胞膜上有很多离子通道,细胞通过这些通道与外界进行离子交换。离子通道在许多细胞活动中都起关键作用,它是生物电活动的基础,在细胞内和细胞间信号传递中起着重要作用。离子通道通过调控细胞内pH值和离子浓度来维持正常的细胞体积及细胞内生物分子活性所需的离子浓度范围。特别是通过改变作为第二信使的钙离子浓度,来调控各种生化过程。生命的很多过程如发育、生长、分泌、兴奋、运动,甚至于学习和记忆都与离子通道功能的正常发挥有直接联系。目前,离子通道的研究已成为分子生物学、分子药理学、生物物理学、神经生物学等多种学科的热点。     

伽玛刀治疗脑转移瘤162例

@@脑转移瘤是颅内最常见的恶性病变,随着恶性肿瘤患者生存时间逐渐延长,脑转移瘤的发病率也逐渐增高。如何合理有效地治疗脑转移瘤,延长患者生存时间,提高生存质量,已越来越引起关注。我科2010-08—2012-08应用头部伽玛刀治疗脑转移瘤患者162例,共228例次,取得了满意的治疗效果,现总结报道如下。     

The synchronization of FitzHugh--Nagumo neuron network coupled by gap junction

It is well known that the strong coupling can synchronize a network of nonlinear oscillators. Synchronization provides the basis of the remarkable computational performance of the brain. In this paper the FitzHugh-Nagumo neuron network is constructed. The dependence of the synchronization on the coupling strength, the noise intensity and the size of the neuron network has been discussed. The results indicate that the coupling among neurons works to improve the synchronization, and noise increases the neuron random dynamics and the local fluctuations; the larger the size of network, the worse the synchronization. The dependence of the synchronization on the strength of the electric synapse coupling and chemical synapse coupling has also been discussed, which proves that electric synapse coupling can enhance the synchronization of the neuron network largely.     

Electrostatic Interactions Determining the Selectivity of KcsA Channel and Its Mutants

We perform the density functional theory and Brownian dynamics simulations based on the three-dimensional structure of the WT KcsA channel and its mutants. Our data suggest that the electrostatic interactions between the channels and cations, within the signature sequence of K^＋ channels, determine the selectivity of the channel.     

神经电信号和运动肌细胞之间的桥梁——烟碱型乙酰胆碱受体通道(NAChR)

 烟碱型乙酰胆碱受体(NAChR)是通过打开或关闭一个跨膜生成孔的门来控制神经和肌肉细胞间的电信号。这个通道是由两部分组成的:直接面向通道的内环(innerring)是由5个α螺旋互相缠绕形成的,它们成放射状地排列,这样就为离子形成了一个逐渐变窄的通道。这个通道的外环(outerring)是由15个α螺旋互相缠绕形成的,它们的作用是将内环和外部的油脂层隔离开来。通道的“门”是一个位于细胞膜中间的一个压缩的疏水性区域(constrictinghydrophobicgirdle),它是靠内环相邻的螺旋之间的微弱作用力而形成。     

The spike timing precision of FitzHugh-Nagumo neuron network coupled by gap junctions

It has been proved recently that the spike timing can play an important role in information transmission, so in this paper we develop a network with N-unit FitzHugh--Nagumo neurons coupled by gap junctions and discuss the dependence of the spike timing precision on synaptic coupling strength, the noise intensity and the size of the neuron ensemble. The calculated results show that the spike timing precision decreases as the noise intensity increases; and the ensemble spike timing precision increases with coupling strength increasing. The electric synapse coupling has a more important effect on the spike timing precision than the chemical synapse coupling.