铜离子(II)抑制Aβ 多肽聚集机理的分子模拟

大脑中淀粉样β多肽(Aβ)的纤维化沉积是Alzheimer氏症(AD)的一个关键性病理事件. 体外实验发现, 近生理浓度的锌离子即有很强的诱导Aβ 聚集的能力. 铜离子在一定条件下能够强烈地抑制锌离子诱导的Aβ 聚集. 铜离子作为体内锌离子的潜在抑制剂引起了人们的关注. 本文通过分子模拟法研究了铜离子抑制Ab聚集的可能机理. 在单环模式中发现Y10残基有明显的促螺旋化作用, [Cu-H13(Nπ)-Y10(OH)]配合物形成了局部准3.010螺旋结构. 在多环模式中发现Q15和E11残基的侧链协同配位使体系能量大幅降低, 变构效应显著. 配合物[Cu-3N-Q15(O)- E11(O1)]和[Cu-H13(Np)-Y10(OH)]由于变构为准螺旋构象, 极可能以可溶形式存在于溶液中. 另外, 发现氢键作用是Ab 聚集的主要驱动力. 以上结果将有助于进一步加深对铜离子与AD致病机制之间关系的理解并制定相应的“抗淀粉样沉积”的治疗策略.     

钇离子及其阳离子卟啉配合物与金黄色葡萄球菌的相互作用

用LKB-2277生物活性检测系统考察了Y~(3+)，TMP及其阳离子型钇卟啉配合物 {[Y(TMP)(H_2O)_3]Cl, TMP = 5, 10, 15, 20-四（4-甲氧基苯基）卟啉}对金黄色 葡萄球菌全程代谢作用的影响，测定了Y~(3+)，TMP和[Y(TMP)(H_2O)_3]Cl对金黄 色葡萄球菌作用的产热曲线，根据产热曲线求算了金黄色葡萄球菌在Y~(3+)，TMP ，[Y(TMP)(H_2O)_3]Cl作用下生长代谢的速率常数k_1，k_2，抑制率I_1，I_2，和 半抑制浓度IC_(50)~1，IC_(50)~2等热动力学参数。实验结果表明：Y~(3+)，[Y (TMP)(H_2O)_3]Cl对金黄色葡萄球菌的生长代谢有双向调节作用，在低浓度下表现 为刺激作用，高浓度为抑制作用，而TMP对金黄色葡萄球菌的生长代谢主要为抑制 作用，在低浓度下表现为刺激作用，高浓度为抑制作用，而TMP对金黄色葡萄球菌 的生长代谢主要为抑制作用，对金黄色葡萄球菌的抑制作用[Y(TMP)(H_2O)_3]Cl > TMP > Y~(3+)。     

A Novel Method for Quantification of Circulating DNA in Serum by Capillary Zone Electrophoresis

In this paper, we first presented a novel method for quantification of circulating DNA in human serum based on capillary zone electrophoresis with laser-induced fluorescence detection (CZE-LIF). The serum was digested by proteinase to release free DNA, and then CZE-LIF system was used for the quantification of total circulating DNA. This method was successfully used to quantify the circulating DNA levels in sera from healthy individuals and certain cancer patients.We found the significantly elevated circulating DNA levels in certain prostate cancer patients. Our results demonstrated that CZE-LIF system has good linearity, excellent sensitivity (0.5 ng/mL DNA),satisfactory reproducibility (RSDs in one day and between days were both less than 5%) and reliability, and is well suitable to the quantification of the circulating DNA in human serum or plasma.     

GIF S-亚硝基化的一些见解

Neural growth inhibitory factor （GIF）, a member of metallothionein family （metallothionein-3, MT3）, was well known by its distinct neural growth inhibitory activity, which is not shown by other MT isoforms. However, till now, people still did not know clearly how GIF exerts its biological functions. Since it has been reported that GIF might serve as NO scavenger and was related to the release of zinc, our study was focused on the interaction of GIF and NO. By studying the reactions of human GIF and human MTlg with SNOC-a type of NO donor, it was found that GIF was more reactive than MT-lg toward SNOC. In order to further figure out if the high reactivity of GIF in this reaction resulted from the acid-base catalysis, several mutants were constructed： E23K, E41G/E43A, E23K/E41G/E43A. By studying their basic properties and the reactions toward SNOC, it was found that the S-nitrosylation of GIF was not only related to the acid-base catalysis, but also to the accessibility of metal-thiolate clusters.     

一种超支化阳离子聚合物的制备及其防膨性能

以顺丁烯二酸酐及二乙醇胺为原料，采用“一步熔融法”合成了端羟基超支化聚酯酰胺（HBP-OH）；以环氧氯丙烷改性HBP-OH制得端基为氯甲基的超支化聚酯酰胺（HBP-ECH）；以三乙胺改性HBP-ECH制得端基为季铵基的超支化聚酯酰胺（HBP-L），其结构经IR表征。研究了HBP-L的静态防膨率、耐水洗能力及对岩心的渗透伤害率。结果表明：HBP-L加量为1 wt%时，粘土防膨率为90.36%；经10次水洗后，其防膨率仍超过85%；模拟地层温度为45 ℃时，HBP-L对岩心的渗透伤害率仅3.86%。采用XRD和Zeta电位法分析了HBP-L对粘土水化膨胀及运移分散的抑制机理。结果表明：经1 wt%HBP-L处理的粘土，其晶层间距为6.91 nm，较去离子水处理层间距（4.71 nm）小；粘土表面的zeta电位由-39.2 mV升高至-19.6 mV。     

离子抑制反相高效液相色谱法测定槐米中芦丁含量的研究

1 引言 芦丁是植物界广泛存在的一种重要的黄酮类化合物,在临床上可用作治疗毛细血管病的药物和治疗高血压病的辅助药物。因此,定量分析植物样品中的芦丁含量具有一定的现实意义。目前,国内有关这方面的工作多采用薄层色谱-紫外分光光度法,本文首次在国内报道采用离子抑制RP-HPLC法测定中草药槐米中     

Effect of Cationic Surfactant on the Inhibition of Ligninase by Hydrogen Peroxide

The inhibition of lingninase by hydrogen peroxide in the presence of cationic surfactant CTAB was studied by kinetic speetrophotometdc technique. Results showed that addition of CTAB enhanced the inhibition by H202, but it did not alter the inhibition pattern and the inhibition constant changed little with theco-ncentration of CTAB. Modification of the enzymic protein by the surfactant monomer may be responsible for the above mentioned results.     

激光雷达距离像相关跟踪中的图像预处理

相干激光雷达距离像预处理是获得最终图像必不可少的步骤,其处理的好坏直接关系到目标识别的正确与否及追踪的稳定性.本文首先通过基于相干激光雷达特性得到仿真激光雷达含噪距离像与强度像,进而对原始噪声图像进行了背景抑制与距离反常抑制(中值滤波)以及二者结合预处理.用基于MCD距离的相关算法对处理前、后图像进行追踪.最后给出跟踪绝对误差.     

一种1V电压工作的高精度CMOS带隙基准源

基于标准1μmCMOS工艺,针对1V供电电压,设计了一种自偏置PTAT电流产生电路和低电源、高增益的运算放大器,最终实现了低电源工作的带隙基准电路.在1V电源电压下,采用1μm CMOS工艺进行仿真,温度系数在-20～120℃范围内达到13×10-6,低频电源抑制比达到-90dB.     

音频传导敏感度试验中的工频电压抑制

基于对试验标准、试验方法和硬件实现的分析,评估了几种已有抑制工频电压方法的不足。提出了一种音频传导敏感度试验中工频电压的抑制方法,并通过较完整的CS101试验过程予以验证。最后,分析了该抑制方法在相关标准中的符合性。