Capillary electrophoresis with electrochemiluminescence detection for measurement of aspartate aminotransferase and alanine aminotransferase activities in biofluids

A new sensitive assay for aspartate aminotransterase (AST) and alanine aminotransferase (ALT) activities in biofluids was developed, based on the separation and detection of alanine, glutamate, and aspartate using capillary electrophoresis (CE) with electrochemiluminescence (ECL) detection. The three amino acids were separated in 5 mM phosphate of pH 2.1 as background electrolyte, and detected on a 500 mu m platinum disk electrode at 1.2 V (versus Ag/AgCl) in the presence of 10 mM tris(2,2'-bipyridyl)ruthenium(II) dissolved in 80 mM phosphate of pH 10.5. A mass detection limit of 37.3 fmol (or 81.5 fmol) for glutamate, corresponding to the product in the enzyme reaction catalyzed by 1.24 x 10(-9) U AST (or 2.72 x 10(-9) U ALT) in a 30 min reaction period, was achieved. This assay was applied to investigate the cytotoxicity effect of ethanol on HepG2 cells and differentiating nonalcoholic steatohepatitis (NASH) from alcoholic liver disease, indicating that the technique is promising for the application in the cell biological and clinical fields.

Hydrothermal synthesis and crystal structure of a novel compound: [Ni(phen)(3)](2)[(SiMo10V2O40)-O-IV((VO)-O-IV)2]center dot 2H(2)O

A novel compound [Ni(phen)(3)](2)[(SiMo10V1/2O40)-O-V((VO)-O-IV)(2)] . 2H(2)O has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction. The compound crystallizes in the triclinic, system, space group P-1, a = 12.378(4) Angstrom, b = 14.148(5) Angstrom, c = 14.316(2) Angstrom, alpha = 105.91(2)degrees, beta = 95.31(2)degrees, gamma = 96.89(3)degrees, V = 2373.0(12) Angstrom(3), Z = 1, (lambdaMo(Kalpha)) = 0.71073 Angstrom, R1 (wR2) = 0.0869(0.2174). Data were collected on a Siemens P4 four-circle diffractometer at 293 K in the range of 1.51 < theta < 22.50degrees using the omega-scan technique. Empirical absorption correction (psi scan) was applied. The structure was solved by the direct method and refined by the Full-matrix least-squares on F-2 using the SHELXL-97 software. X-ray crystallographic study showed that the title compound contained a bi-capped alpha-Kegin-type [(SiMo10V2O40)-O-IV((VO)-O-IV)(2)](4-) polyoxoanion.

Asymmetric polymerization of menthyl methacrylate by anionic catalysts

In this paper, (-)menthyl methacrylate((-)MnMA) was polymerized at -78degreesC in toluene with three types of anionic catalysts, which were complexes of fluorenyllithium with (-)sparteine -((-)-Sp), (S, S)-(+)-2, 3-dimethoxy-1, 4-bis(dimethylamino)butane((+)DDB) and N,N,N,N'-tetramethylethylenediamine(TMEDA), and the chiral optical property of the obtained polymer was studied. The circular dichroism (CD) spectrum of the polymer showed negative Cotton effect.

Charge transport in a blue-emitting alternating block copolymer with a small spacer to conjugated segment length ratio

We analyze current versus voltage data obtained using single carrier injection in several metal/polymer/metal sandwich structures. The polymer used in each case is a soluble blue-emitting alternating block copolymer. Our experimental results demonstrate that the electron transport is space-charge limited by the high density of traps having an exponential energy distribution (temperature dependent characteristic energy) in the copolymer. The electron mobility of 8x10(-10) cm(2)/V s is directly determined using space-charge-limited current analytical expressions. Hole transport is also space-charge limited, with a mobility of 2x10(-6) cm(2)/V s. A hole trap with energy 0.17 eV is observed. We compare these results with those obtained for related block copolymers with different spacer and conjugated segment lengths and discuss the influence of spacer length and conjugated segment length on the charge transport properties. (C) 2000 American Institute of Physics. [S0021-8979(00)04501-1].

Synthesis and structural characterization of a novel polymeric praseodymium(III) complex with a new flexible double betaine

A novel polymeric Pr(III) complex with a new double betaine, namely [{Pr(L-1)(1.5)(H2O)(2)}(n)] [ClOli4]3(n). nH(2)O (1) (L-1= 1,4-diazoniobicyclo[2,2,2]octane- 1,4-dipropionate), has been synthesized and characterized by X-ray analysis. In the title complex, the Pr(III) atom is nine-coordinated by seven oxygen atoms from five L-1 ligands and two aqua ligands. Each pair of adjacent praseodymium(III) atoms is linked by a pair of mu(3) chelating and bridging carboxylate groups, thus forming an infinite metal metal chain running parallel to the a direction, and such chains are cross-linked by flexible backbones of L-1 ligands into a three-dimensional network with the perchlorate anions and lattice water molecules accommodated in the interstitial space. The title complex crystallizes in the monoclinic space group P2(1)/n with a = 8.085(2), b = 14.316(3), c = 29.775(6) Angstrom, beta = 103.04(3)degrees and Z = 4.

Crystallization process and morphology structure of poly(aryl ether ether ketone ketone) containing meta-phenyl links

The crystallization process and morphology of poly(aryl ether ether ketone ketone) containing meta-phenyl links (PEEKmK) have been investigated by transmission electron microscopy and electron diffraction. The results indicate that the thin films of PEEKmK isothermally crystallized from both the glassy state and the melt at the temperature range of 180 similar to 250 degrees C consist of two kinds of morphological forms, i. e. large (order of mu m), flat-on single crystals and narrow, lath-like, edge-on lamellae, The latter consists of the spherulites. Meanwhile, the growing process of the two kinds of morphological forms has been discussed.

含间苯连接的聚醚醚酮酮的等温结晶过程和形态结构

用透射电子显微镜和电子衍射方法研究了含间苯连接的聚醚醚酮酮（PEEKmK）溶液浇铸薄膜的等温结晶过程和形态结构．结果表明，PEEKmK无论从玻璃态结晶还是从熔体结晶均能形成2种不同取向的结晶形态结构，即平放片晶和侧放片晶；前者c轴垂直于膜平面，后者c轴平行于膜平面．其结晶发展过程为先形成平放单晶状片晶，随着时间的增长，在单晶上开始生长侧放片晶，逐渐发展形成球晶，最终形成2种不同取向的单晶和球晶共存的结晶形态结构.

STRUCTURE-PROPERTY RELATIONSHIP BETWEEN HALF-WAVE POTENTIALS OF ORGANIC-COMPOUNDS AND THEIR TOPOLOGY

A significant correlation was found between half-wave potentials of organic compounds and their topological indices, A(x1), A(x2), and A(x3). The simplicity of calculation of the index from the connectivity in the molecular skeleton, together with the significant correlation, indicates its practical value. Good results have been obtained by using them to predict the half-wave potentials of some organic compounds.

四甲基乙撑桥联二环戊二烯基环戊二烯基稀土配合物的合成与表征

合成了四个甲基乙撑桥联二环戊二烯基环戊二烯基稀土四氢呋喃配合物,采用元素分析、红外光谱、核磁共板、热失重和质谱等方法对所得到配合物进行表征,并用X光衍射法测得Me_4C_2(C_5H_4)_2SmC_5H_3(THF)的晶体结构。该晶体属正交晶系C_(e2a)空间群,a=1.1696(6),b=1.2539(5),c=2.9432(15)nm;V=4.316(4)nm~3,z=8,D_c=1.54g·cm~(-3)。三个环戊二烯基Sm-C(η~5)距离分别为0.272(3),0.276(3),0.278(3)nm和Sm-O键长为0.253(1)nm。

LIQUID-CHROMATOGRAPHY WITH ELECTROCATALYTIC DETECTION OF CYSTEINE, N-ACETYLCYSTEINE AND GLUTATHIONE BY A PRUSSIAN BLUE FILM-MODIFIED ELECTRODE

Chemically modified electrodes prepared by adsorbing prussian blue on a glassy carbon electrode are shown to catalyse the electro-oxidation of cysteine, N-acetylcysteine and glutathione in acidic media. The catalytic response is evaluated with respect to the potential scan rate, the solution pH, the concentration dependence, and other variables. Covering the electrode with Nafion(R) film improved the stability and reproducibility in liquid chromatography with electrochemical detection to the extent that repetitive sample injections produced relative standard deviations of less than 5% over several hours of operation. The limit of detection was 4 pmol for cysteine, 33 pmol for glutathione and 61 pmol for N-acetylcysteine.

钕激光晶体结构、组成和光谱特征研究

本文在考虑交叉弛豫过程的情况下,研究了含Nd~(3+)激光晶体Y_3Al_5O_(12)YAlO_3,LiYF_4和NdP_5O_(14)的辐射跃迁几率、荧光寿命和荧光分支比,解速率方程得到了各能级上粒子数和Nd~(3+)浓度的关系,讨论和比较了四种激光晶体的光谱特征。

Refining near-native protein-protein docking decoys by local resampling and energy minimization

How to refine a near-native structure to make it closer to its native conformation is an unsolved problem in protein-structure and protein-protein complex-structure prediction. In this article, we first test several scoring functions for selecting locally resampled near-native protein-protein docking conformations and then propose a computationally efficient protocol for structure refinement via local resampling and energy minimization. The proposed method employs a statistical energy function based on a Distance-scaled Ideal-gas REference state (DFIRE) as an initial filter and an empirical energy function EMPIRE (EMpirical Protein-InteRaction Energy) for optimization and re-ranking. Significant improvement of final top-1 ranked structures over initial near-native structures is observed in the ZDOCK 2.3 decoy set for Benchmark 1.0 (74% whose global rmsd reduced by 0.5 angstrom or more and only 7% increased by 0.5 angstrom or more). Less significant improvement is observed for Benchmark 2.0 (38% versus 33%). Possible reasons are discussed.

Effective dielectric response of graded spherical composites

The effective dielectric response of composites containing graded material is investigated when an external uniform electric field E-0 is applied to it. For a spherical particle with gradient dielectric constant, epsilon(i) (r) = b + cr, randomly embedded in a host with dielectric constant epsilon(m), we have obtained the exact solution of local electric potential in the composite media regions, which obey a linear constitutive relation D = epsilonE, using hypergeometric function. In dilute limit, the effective dielectric response of the linear graded composite media is derived. Furthermore, for larger volume fraction, we have given an effective medium approximation to estimate the effective dielectric response of the graded composite media. (C) 2003 Elsevier B.V All rights reserved.

双壳贝类幼虫变态诱导及其机理研究

变态过程是双壳贝类由幼虫向成体转变的一个必不缺少的发育阶段。研究双壳贝类幼虫的变态过程及其机理，对于阐明它们的种群数量变动，促进重要经济双壳贝类增养殖的发展有重要的理论和实践意义。本论文除了用化学物质对几种双壳贝类(海湾扇贝、墨西哥湾扇贝和硬壳蛤)幼虫的变态进行诱导外，主要以激素和神经递质的作用方式为基础，通过直接测定双壳贝类(以海湾扇贝为代表)幼虫体内激素和神经递质、第二信使cAMP等生化物质含量的变化来研究双壳贝类幼虫变态过程中的信息传递途径，从分子生物学和神经生物学角度阐明双壳贝类幼虫变态机理。主要结果如下：1．通过参考国内外大量文献的基础上，较为系统地评述了近二十年来海洋无脊椎动物幼虫附着变态研究的一些进展情况，主要包括诱导因子、附着变态机理模型、人工诱导物的应用和延迟变态四个方面。到目前为止，人们已经发现了许多海洋无脊椎动物幼虫附着变态的诱导物质，主要分为天然诱导物和人工诱导物两大类，一些人工诱导物如GABA、肾上腺素和去甲肾上腺素已经在经济贝类苗种生产中得到应用。幼虫附着变态机理模型主要有长牡蛎(Crassostrea gigas)幼虫附着变态的双调控模型、红鲍(Haliotis rufescens)幼虫附着变态的上行调节模型以及多毛类Phragmatopoma california幼虫附着变态的脂肪酸调控模型。本论文还评述了海洋无脊椎动物幼虫发生延迟变态的原因以及延迟变态对海洋无脊椎动物造成的影响，并提出了解决的方法和今后研究的重点问题。2．在室内用氯化乙酰胆碱、ATP和CaCl_2 3种化学物质对海湾扇贝幼虫的变态进行了诱导实验。结果表明，虽然在个别浓度和处理时间氯化乙酰胆碱和ATP有诱导作用，但总体诱导效果不显著。而10×10~(-3)～40×10~(-3M的CaCl_2在处理12～24h后诱导效果较显著，其诱导效果对处理时间的依赖性较显著，在浓度为40×10~(-3)M和处理时间为24h时诱导效果最好，与对照组相比，变态率提高23.18％。3种诱导物对幼虫死亡率均有显著影响，并且死亡率对浓度和处理时间均有显著的依赖性，浓度越高，处理时间越长，死亡率越高。3．用KCl、肾上腺素、去甲肾上腺素和氯化胆碱进行了墨西哥湾扇贝(Argopectenirradians concentricus Say)幼虫变态的诱导作用实验。结果表明，KCl、肾上腺素、去甲肾上腺素和氯化胆碱对墨西哥湾扇贝幼虫变态均有显著诱导作用。KCl在处理时间为12h～48h范围内均有诱导作用；13.42×10~(-3)M和20.13×10~(-3)M的KCl诱导效果较好，变态率平均提高10％以上。1．O×10~(-6)M～50×10~(-6)M的肾上腺素在处理时间为lh～12h较适宜，此时变态率均提高10％以上。1.0×10~(-6)M～50×10~(-6)M的去甲肾上腺素在处理时间为1h～24h都较适宜，变态率平均均提高10％以上，最高可提高31．07％。0.01×10~(-4)M～1.O×10~(-4)M的氯化胆碱在处理时间为12h～48h时诱导效果均较好，它们之间的平均变态提高率并没有显著差别，均在12％～13％之间。10×10~(-4)M的氯化胆碱在处理时间为12h时诱导效果较明显，变态率可以提高19.14％，超过12h，变态率明显下降，100×10~(-4)M的氯化胆碱明显产生毒害作用，幼虫变态率均为零，而幼虫的死亡率均为100％。4．用KCl、肾上腺素、去甲肾上腺素、L-DOPA、5-羟色胺(5-hydroxytryptamine，Serotonin，5-HT)和GABA(γ-氨基丁酸)进行了不同浓度不同处理时间对硬壳蛤(Mercenaria mercenaria L.)幼虫变态诱导实验。结果表明，KCl、肾上腺素、去甲肾上腺素、L-DOPA和5-羟色胺对硬壳蛤幼虫的变态均有诱导作用，而GABA的诱导 作用不显著。KCl的最佳诱导浓度随处理时间不同而有所不同。当处理时间为1～24h时，KCl的最佳诱导浓度为33.56×10~(-3)M，此时幼虫变态率均提高24％以上，当处理时间为48h时，KCl的最佳诱导浓度为20.13～26.85×10~(-3)M，处理时间为72h时，最佳诱导浓度为13.42×10~(-3)M。肾上腺素和去甲肾上腺素的诱导作用与浓度和处理时间均有关。肾上腺素的最佳处理浓度为100×10~(-6)M，最佳处理时间均为8h，此时幼虫变态率提高最大，为36.97％。当去甲肾上腺素的诱导浓度为100×10~(-6)M，处理时间为8h～16h时，幼虫变态提高率较高，均大于18％，死亡提高率均低于30％，当去甲肾上腺索诱导浓度为500×10~(-6)M时，虽然在8h～16h的处理时间范围内，幼虫变态提高率也较高，均大于18％，但当处理时间超过8h，在16～48h范围内，幼 虫死亡提高率明显升高，均大于50％。L-DOPA的适宜诱导浓度为10×10~(-6)M～50×10~(-6)M，适宜处理时间为8～24h，此时幼虫变态率均提高30％以上，最高可提高79.43％。5-羟色胺的诱导作用较强，其适宜诱导浓度为100×10~(-6)M—1000×10~(-6)M，适宜处理时间为0.5～24h，此时幼虫变态率提高均在30％以上，当处理时间为8h时，最佳诱导浓度为1000×10~(-6)M，此时幼虫变态率提高57.5％，当处理时间为24h时，最佳诱导浓度为100×10~(-6)M，此时幼虫变态率提高69.29％。GABA的诱导作用较弱，最佳诱导浓度随处理时间的不同而有所不同。处理时间为24h和48h时，最佳诱导浓度为0.1×10~(-6)M；处理时间为0.5～16h时，最佳诱导浓度为100×10~(-6)M。5．KCl、肾上腺素、去甲肾上腺索、L-DOPA、5-羟色胺、GABA、茶碱和咖啡因8种诱导物对不同发育阶段海湾扇贝幼虫变态的诱导作用是不同的。13．42×10~(-3)M和20.13×10~(-3)M的KCl对第12天幼虫的变态有抑制作用，变态提高率为负值；之后当幼虫发育至第13和14天时，两浓度的KCl能够明显诱导幼虫变态，变态提高率均高于20％，而对于第16天的幼虫诱导作用有所减弱，变态提高率有所降低；26.85×10~(-3)M的KCl对第12和13天幼虫的变态均有抑制作用，变态提高率为负值，对第14和16天幼虫的变态却有明显的持续的诱导作用，变态提高率分别为22.98％和37.5％。神经递质肾上腺素、去甲肾上腺素、L-DOPA、5-羟色胺和GABA的诱导作用规律基本相似，即对第13天海湾扇贝幼虫的变态有明显的抑制作用，变态提高率均为负值，而对第14天幼虫的诱导作用较显著。茶碱和咖啡因作为影响细胞内cAMP的物质，它们的诱导作用规律与神经递质有所不同。它们对第13天海湾扇贝幼虫变态的诱导效果最好。6．测定了不同发育阶段及人工诱导后海湾扇贝幼虫体内去甲肾上腺素、多巴胺和5-羟色胺含量的变化规律。结果表明，海湾扇贝幼虫体内去甲肾上腺索含量在变态前和变态后没有明显变化，变态前为2352(pg／mg湿重)，变态后为2770(pg／mg湿重)。多巴胺和5-羟色胺含量在变态前随幼虫的发育而增加，变态前(第13天)急剧增加，第13天的幼虫比第12天的幼虫分别增加了2.8倍和5.7倍，变态后急剧下降，变态后幼苗比第13天的幼虫分别降低了25.1倍和16.4倍。海湾扇贝幼虫体内DA：NE比和5-HT：NE比在变态前和变态后变化比较剧烈。DA：NE比和5-HT：NE比在变态前(第13天)急剧增加，第13天的幼虫比第12天的幼虫增加了3.O倍(DA：NE比)和5.0倍(5-HT:NE比)；变态后急剧降低，变态后幼苗比第13天的幼虫降低了29.8倍(DA：NE比)和19.5倍(5-HT：NE比)。海湾扇贝幼虫经KCl和氯化钙诱导24h后，体内去甲肾上腺素、多巴胺和5-羟色胺以及DA：NE比和5-HT：NE比均有所降低。本实验的结果表明，多巴胺和5-羟色胺可能启动了海湾扇贝幼虫的变态过程。7．茶碱和咖啡因对墨西哥湾扇贝幼虫的变态均有明显诱导作用。它们的诱导作用均对浓度的依赖性较强，对处理时间的依赖性较弱。10×10~(-4)M的茶碱诱导效果最好，平均变态提高率达33％，其次为1.0×10~(-4)M和100×10~(-4)M的茶碱，平均变态提高率分别为23.15％和21.97％。处理时间对茶碱诱导效果影响不显著，在1～24h范围内，平均变态提高率在19.07～26.1％之间变动。10×10~(-4)M的咖啡因诱导效果最佳，4个处理时间的平均变态提高率为36.01％，其次为100×10~(-4)M，平均变态提高率为26.43％。处理时间对茶碱的诱导效果影响不大，在1～24h范围内，平均变态提高率在19.65～22.02％之间变动。8．采用直接测定cAMP的方法来研究cAMP是否参与了海湾扇贝幼虫的变态过程。结果表明，cAMP参与了海湾扇贝幼虫的变态过程。海湾扇贝幼虫体内cAMP含量随着发育阶段的不同而有所变化。在D形幼虫期最低，为73 pmol／(mg蛋白质)；当到达壳顶期幼虫时cAMP含量明显增加，比D形幼虫期提高了12.7倍。从壳顶期幼虫到眼点幼虫(100％，第13天)cAMP含量增加速度较慢，各发育阶段分别比前一发育阶段增加了0.4倍、0.3倍和0.2倍。但当幼虫变态后，体内cAMP含量又急剧增加，幼苗体内cAMP含量比眼点幼虫(100％，第13天)增加了6.1倍。当用KCl、肾上腺索和L-DOPA诱导后，幼虫体内cAMP含量明显增加，分别比对照组提高了7.8倍、1.5倍和10.7倍，说明cAMP参与了这3种诱导物诱导海湾扇贝幼虫变态的过程。9．在前面实验结果和参考有关文献的基础上，初步提出了以海湾扇贝为代表的双壳贝类幼虫变态机理模型：幼虫变态分为两个过程：启动过程和后续过程。当幼虫发育到一定阶段，在外界刺激因子的作用下，体内分泌多巴胺和5-羟色胺，多巴胺和5-羟色胺通过某种信号转导途径(如以DG和IP_3为第二信使)启动变态过程，变态过程启动后，又激活以cAMP为第二信使的信号转导途径(暂时称为后续过程)，两者共同完成了幼虫的变态过程。