Dioxin-like components in human breast milk collected from Hong Kong and Guangzhou

The H4IIE rat hepatoma cell line was employed as a cell model to screen 7-ethoxyresorufin O-deethylase (EROD)-TCDD equivalents (EROD-TEQ) of human breast milk samples collected from Hong Kong and Guangzhou, China. The screening methods employed a 96-well plate spectrofluorometer-EROD assay. For cell-line validation, our results demonstrated a dose-dependent increase in the Ah receptor-mediated response (i.e., CYP1A1 mRNA and EROD) of the cells upon exposure to a number of known Ah receptor agonists, including 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 2,3,7,8-tetrachlorodibenzothiophene, benzo[a]pyrene, and beta-naphthaflavone. TCDD induced CYP1A1 mRNA and EROD was in a close positive correlation (r = 0.98). For the screening of dioxin-like compounds, breast milk samples collected during lactation weeks 3-5 were used. One hundred (from Hong Kong) and 48 (from Guangzhou) breast milk samples were assayed, of which 65% and 68% of the samples, respectively, showed detectable dioxin-like activities using the H4IIE cell EROD screening method. For sixty-five samples from Hong Kong the mean EROD-TEQ values ranged from 58.1 to 96.5 pg/g of milk fat for those aged 21-36 years while 32 samples from Guangzhou had mean values of 98.8-202.1 pg/g of milk fat. In comparisons of the EROD-TEQ values for different age groups from both cities, there were no significant differences (P < 0.05). However, the mean and median EROD-TEQ values of the Guangzhou population were in general higher than those of the Hong Kong population. The results of the present study indicate that it is feasible to use the H4IIE cell-line as a model for screening dioxin-like compounds in human breast milk. In addition, the method is rapid and cost-effective, particularly for a routine and high-throughput sample screening analysis, compared to the costly and time-intensive chemical analytical techniques. (C) 2003 Elsevier Inc. All rights reserved.

大麻受体CB1及CB2在慢性吗啡成瘾大鼠中枢神经系统与免疫系统的分布和表达

吗啡是临床常用的镇痛药物之一，通过模拟内源性抗痛物质脑啡肽的作用，激活中枢神经阿片受体而产生强大的镇痛作用。吗啡属于阿片类生物碱，为阿片受体激动剂，是目前我国主要的毒品成瘾类型之一，对人民生命健康危害极大。目前我国登记在册的吗啡成瘾者约有100万，每年导致的直接经济损失超过1000亿元。因此吗啡成瘾机制的研究以及治疗，是目前神经疾病的研究重点之一。 吗啡成瘾与其结合的受体有关。吗啡除结合阿片受体外，也可能结合大麻素受体，现发现体内有两种大麻素受体的存在：CB1受体和CB2受体。大麻CB1、CB2受体都是G蛋白耦联受体。其中CB1受体主要位于脑、脊髓与外周神经系统中，脑内CB1受体主要分布于基底神经节（黑质、苍白球、外侧纹状体）、海马CA锥体细胞层，小脑和大脑皮层。因此推测大麻CB1受体的功能可能与成瘾、记忆、认知、运动控制的调节有关。而大麻CB2受体主要分布于外周组织，如脾脏边缘区、扁桃体等，它的这种分布可能与免疫抑制作用有关。近来的研究发现大麻CB2受体在中枢神经系统也有分布，目前对其在此分布的功能不明确，推测可能与成瘾、抑郁症等神经类疾病有密切关系。 在药物成瘾导致的精神依赖作用中，奖赏效应是各种药物成瘾的药理学基础。中脑—边缘系统（(mesolimbic dopamine system,MLDS)是药物奖赏效应的神经解剖学基础。目前认为内源性大麻素所起的药理作用与多巴胺能和阿片能的神经传递有密切的关系。因此推断大麻素CB1受体与慢性吗啡成瘾有密切关系，至少是部分参与到慢性吗啡成瘾过程中。 相较于较多的关于大麻CB1受体的研究，有关大麻CB2受体的研究很少。尽管近来证实大麻CB2受体也分布于中枢神经系统，但在慢性吗啡成瘾时，大麻CB2受体表达的改变仍不清楚。在本项目中，我们将对慢性吗啡成瘾动物通过分子生物学、蛋白质化学、免疫组织化学的方法，探讨大麻CB2受体在中枢神经系统的分布和表达，以及大麻CB2受体在吗啡成瘾中可能的作用。 吗啡对免疫系统有抑制作用, 包括抑制淋巴细胞增殖, 减少细胞因子的分泌，减弱自然杀伤细胞（NKC）的细胞毒作用。现已证实激活周围神经系统的CB2受体可诱导IL-4的生成，从而影响阿片μ型受体的转录。此发现提供了内源性大麻系统-阿片系统-免疫系统之间存在相互作用的关系。然而，吗啡吸食是否通过CB2受体从而导致免疫功能的抑制，现在还没有直接证据，在本实验中我们将探讨CB2受体与吗啡成瘾导致免疫功能的改变有关。 实验结果显示（1）应用RT-PCR法，检测到大麻素受体CB1在慢性吗啡成瘾大鼠的皮质和海马处mRNA表达水平与对照组大鼠有明显不同。（2）应用western免疫印迹法，检测到大麻素受体CB1在慢性吗啡成瘾大鼠的皮质，海马和脑干处蛋白表达水平与对照组大鼠有明显不同。在脑干处，虽然mRNA表达水平无变化，但蛋白质的表达水平上升。（3）应用免疫组化检测到大麻素受体CB1在大鼠的皮质，海马，脑干，小脑处都广泛分布。（4）应用RT-PCR法，检测到大麻素受体CB2在慢性吗啡成瘾大鼠的皮质，海马，脑干处mRNA表达水平与对照组大鼠有明显不同。（5）应用western免疫印迹法，检测到大麻素受体CB2在慢性吗啡成瘾大鼠的皮质，海马，脑干蛋白表达水平与对照组大鼠有明显不同。且蛋白质的表达改变趋势与mRNA表达水平的改变相似。（6）应用免疫组化法检测到大麻素受体CB2在大鼠的皮质，海马，脑干，小脑处都广泛分布。但数量明显少于大麻CB1受体。（7）应用直接ELISA法，检测到慢性吗啡成瘾大鼠的血清与对照组大鼠的血清比较，IgM表达下降；IgG表达上升。 实验结果提示大麻受体CB1和CB2 很可能在慢性吗啡成瘾过程起着重要的作用，至少是部分参与到慢性吗啡成瘾的过程中。因为大麻素受体CB1和CB2都属于G 蛋白耦连受体，长期持续使用吗啡，其表达的变化可能会导致cAMP信号通路的上调；提高了腺苷酸环化酶(AC)和蛋白激酶A(PKA)的活性从而激活下游相关基因的表达最终导致成瘾。此外大麻素受体CB1和CB2表达的变化可能与慢性吗啡成瘾后免疫功能的改变有相关性。 通过以上的的实验结果，可以得到以下的结论：（1）我们验证了大麻素受体CB1在慢性吗啡成瘾大鼠的皮质，海马和脑干处mRNA和蛋白质表达水平与对照组大鼠有明显不同，且大麻CB1受体在大鼠中枢神经系统中广泛大量分布，表明大麻素受体CB1很可能在慢性吗啡成瘾过程中起着重要的作用，至少部分参与到慢性吗啡成瘾的过程中。（2）我们第一次证实了大麻素受体CB2在吗啡成瘾大鼠的皮质，海马和脑干处mRNA和蛋白质表达水平与对照组大鼠有明显不同，且大麻CB2受体在大鼠中枢神经系统中少量广泛分布。表明大麻素受体CB2很可能在慢性吗啡成瘾过程中起着重要的作用，至少部分参与到慢性吗啡成瘾的过程中。（3）同时我们发现大麻素受体CB1和CB2在大鼠脑组织中广泛表达，表明内源性大麻系统有可能广泛的参与各种神经疾病，很可能成为治疗的新靶点。（4）最后我们发现慢性吗啡成瘾大鼠血液中IgM表达下降；IgG表达上升，表明慢性吗啡成瘾对机体的免疫功能有广泛的调节作用。慢性吗啡成瘾大鼠血清CB2受体mRNA表达上升。我们证实了大麻受体CB2可能正是把神经系统和免疫系统相联系的一个靶点。

TRPV1 受体调控海马突触可塑性的机制及其功能意义

全世界有四分之一人口的日常饮食中包含辣椒及其相关食品，辣椒素是辣椒 里使人产生辛辣和呛感觉的主要成分。辣椒素受体最初是在感觉神经元克隆到 的，后来被命名为TRPV1，是因为发现它属于TRP（Transient receptor potential，瞬时受体势）离子通道家族。辣椒素及其受体在疼痛学领域已有广 泛的研究，但它们如何调节脑功能却知之甚少。很多报道显示辣椒素受体在脑内 广泛表达。在啮齿类动物的海马内，辣椒素受体从齿状回到CA3-CA1区均有表达。 在亚细胞层次，辣椒素受体在神经元胞体，树突棘和突触部位均有表达。近年来 辣椒素受体的内源性配体也被发现，包括花生四烯酸乙醇胺（anandamide, AEA）、 氮磷脂-多巴胺(N-arachidonoyl-dopamine, NADA)、 精胺等。辣椒素在很多脑 区（包括海马），可通过其受体调节神经元兴奋性和神经递质释放。 海马双向突触可塑性，长时程增强(LTP)和抑制现象(LTD)被认为是学习与记 忆的细胞机制。而LTP/LTD的诱导阈值是由 NMDA受体的激活程度及其引起的突 触后胞内钙水平决定的。因此调节NMDA受体和胞内钙信号被认为是调节LTP/LTD 诱导阈值最直接有效的方式。考虑到辣椒素受体的突触分布及其对钙离子的高通 透性，我们认为辣椒素受体的激活可能参与调节LTP/LTD的诱导阈值 本研究采用离体脑片场电位记录方式，发现辣椒素易化LTP的诱导而损伤了 LTD的诱导，并且降低了LTP/LTD的诱导阈值。在给予辣椒素受体的拮抗剂以后， 或者是在TRPV1基因敲除小鼠的脑片上，辣椒素对LTP/LTD的诱导均没有影响。 我们发现的辣椒素对LTP/LTD的影响与行为学应激对LTP/LTD的影响，两者效应恰恰相反，应激是易化LTD的诱导而损伤LTP的诱导。如期所料，辣椒素使应激 损伤的LTP恢复，同时阻断了应激易化的LTD。除了对LTP/LTD有重要的调节作 用以外，我们的结果也显示应激严重损伤了动物对空间记忆的提取。所以我们进 一步研究辣椒素能否对抗应激对动物空间记忆的损伤。我们发现海马内埋置导管 给予辣椒素可以使应激损伤的空间记忆得到恢复，同样，灌胃给予辣椒素也可以 对抗应激对动物空间记忆的损伤，进一步提示日常饮食中的辣椒会对应激相关的 精神障碍有潜在的正面影响。 从动物实验到临床实验都有广泛的证据表明应激对认知功能，焦虑，创伤后 应激综合症等有着深刻的影响。综上所述，我们第一次报道了辣椒素通过激活 TRPV1受体可以对抗应激引起的空间记忆损伤，该效应可能是通过调节LTP/LTD 的诱导阈值来实现的。我们工作的意义在于揭示了辣椒素受体在应激相关的精神 疾病中的潜在作用，为寻找治疗应激相关的精神心理障碍提供了新的靶点，也为 辣椒偏好的饮食习惯与精神卫生之间的关系研究提供了新的思路。

Detection of neurotransmitters by a light scattering technique based on seed-mediated growth of gold nanoparticles

A simple light scattering detection method for neurotransmitters has been developed, based on the growth of gold nanoparticles. Neurotransmitters (dopamine, L-dopa, noradrenaline and adrenaline) can effectively function as active reducing agents for generating gold nanoparticles, which result in enhanced light scattering signals. The strong light scattering of gold nanoparticles then allows the quantitative detection of the neurotransmitters simply by using a common spectrofluorometer.

In situ PEI and formic acid directed formation of Pt NPs/MWNTs hybrid material with excellent electrocatalytic activity

A hybrid material based on Pt nanoparticles (Pt NPs) and multi-walled carbon nanotubes (MWNTs) was fabricated with the assistance of PEI and formic acid. The cationic polyelectrolyte PEI not only favored the homogenous dispersion of carbon nanotubes (CNTs) in water, but also provided sites for the adsorption of anionic ions PtCl42- on the MWNTs' sidewalls. Deposition of Pt NPs on the MWNTs' sidewalls was realized by in situ chemical reduction of anionic ions PtCl42- with formic acid. The hybrid material was characterized with TEM, XRD and XPS. Its excellent electrocatalytic activity towards both oxygen reduction in acid media and dopamine redox was also discussed.

Electrochemical Sensing and Biosensing Platform Based on Chemically Reduced Graphene Oxide

In this paper, the characterization and application of a chemically reduced graphene oxide modified glassy carbon (CR-GO/GC) electrode, a novel electrode system, for the preparation of electrochemical sensing and biosensing platform are proposed. Different kinds of important inorganic and organic electroactive compounds (i.e., probe molecule (potassium ferricyanide), free bases of DNA (guanine (G), adenine (A), thymine (T), and cytosine (C)), oxidase/dehydrogenase-related molecules (hydrogen peroxide (H2O2/beta-nicotinamide adenine dinucleotide (NADH)), neurotransmitters (dopamine (DA)), and other biological molecules (ascorbic acid (AA), uric acid (UA), and acetaminophen (APAP)) were employed to study their electrochemical responses at the CR-GO/GC electrode, which shows more favorable electron transfer kinetics than graphite modified glassy carbon (graphite/GC) and glassy carbon (GC) electrodes.

Sensitive biomimetic sensor based on molecular imprinting at functionalized indium tin oxide electrodes

We initially report an electrochemical sensing platform based on molecularly imprinted polymers (MIPs) at functionalized Indium Tin Oxide Electrodes (ITO). In this research, aminopropyl-derivatized organosilane aminopropyltriethoxysilane (APTES), which plays the role of functional monomers for template recognition, was firstly self-assembled on an ITO electrode and then dopamine-imprinted sol was spin-coated on the modified surface. APTES which can interact with template dopamine (DA) through hydrogen bonds brought more binding sites located closely to the surface of the ITO electrode, thus made the prepared sensor more sensitive for DA detection. Potential scanning is presented to extract DA from the modified film, thus DA can rapidly and completely leach out. The affinity and selectivity of the resulting biomimetic sensor were characterized using cyclic voltammetry (CV). It exhibited an increased affinity for DA over that of structurally related molecules, the anodic current for DA oxidation depended on the concentration of DA in the linear range from 2 x 10(-6) M to 0.8 x 10(-3) M with a correlation coefficient of 0.9927.In contrast, DA-templated film prepared under identical conditions on a bare ITO showed obviously lower response toward dopamine in solution.

Tris(2,2 '-bipyridyl)ruthenium(II) electrochemiluminescent detection of coreactants containing aromatic diol group by the interaction between diol and borate anion

Previous studies show that aromatic diols inhibited Ru(bpy)(3)(2+) electrochemiluminescence (ECL), and all reported Ru(bpy)(3)(2+) ECL methods for the determination of aromatic diols-containing coreactants are based on inhibition of Ru(bpy)(3)(2+)/tripropylamine ECL. In this study, the interaction between diol and borate anion was exploited for Ru(bpy)(3)(2+) ECL detection of coreactants containing aromatic diol group using epinephrine as a model analyte. The interaction prevented from the inhibition of Ru(bpy)(3)(2+) ECL by aromatic diol group of epinephrine. As a result, epinephrine was successfully detected in the absence of tripropylamine simply by using borate buffer solution as the supporting electrolyte. Under the optimum conditions, the log of the ECL intensity increases linearly with the log of epinephrine concentrations over the concentration range of 1.0x10(-9)-1.0x10(-4) M. The detection limit is 5.0x10(-10) M at a signal-to-noise ratio of three. The proposed method exhibit wider dynamic range and better detection limit than that by inhibited Ru(bpy)(3)(2+) ECL method. The relative standard deviation for 14 consecutive determinations of 5 mu M epinephrine was 3.5%. The strategy by interaction with borate anion or boronate derivatives is promising for the determination of coreactants containing aromatic diol group or aromatic hydroxyl acid group. Such interaction can also be used to avoid interference from aromatic diols or aromatic hydroxyl acids.

Electrocatalytic oxidation of catechol at multi-walled carbon nanotubes modified electrode

In 0.05 mol/L phosphate buffer solution (pH 7.0), carbon nanotubes modified electrode exhibits rapid response, strong catalytic activity with high stability toward the electrochemical oxidation of catechol. The electrochemical behavior of catechol on both the multi-walled and single-walled carbon nanotubes modified electrode was investigated. The experimental conditions, such as pH of the solution and scan rate were optimized. The currents (measured by constant potential amperometry) increase linearly with the concentrations of catechol in the range of 2.0 x 10(-5) - 1.2 x 10(-3) mol/L. Moreover, at the multi-walled carbon nanotubes modified electrode the electrochemical responses of catechol and ascorbic acid can be separated clearly.

Electrochemical characteristics of facile prepared carbon nanotubes-ionic liquid gel modified microelectrode and application in bioelectrochemistry

The carbon nanotubes (CNTs) based microelectrode (ME) by modifying CNTs-room temperature ionic liquid (IL) gel at carbon fiber microelectrode (CFME) is easily prepared, which exhibits the typical cyclic voltammogram of ME with sigmoid shape and possesses good stability, high conductivity and enlarged current response and tunable dimension. The direct electron transfer of glucose oxidase has been greatly promoted showing reversible electrochemical behavior even at high scan rate. In addition, the CNTs based ME also exhibits effectively electrocatalytic oxidized ability to biomolecules, e.g. dopamine (DA), ascorbic acid (AA) and dihydronicotinamide adenine dinucleotide. The obvious separation of oxidized peak potential for DA and AA makes it possible to selectively determine DA in presence of AA. These phenomena show that the CNTs based ME has promising potential to detect various species in vivo and in vitro.

Multilayer films of carbon nanotubes and redox polymer on screen-printed carbon electrodes for electrocatalysis of ascorbic acid

Multilayer films containing multiwall carbon nanotubes and redox polymer were successfully fabricated on a screen-printed carbon electrode using layer-by-layer (LBL) assembled method. UV-vis spectroscopy, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy and electrochemical method were used to characterize the assembled multilayer films. The multilayer films modified electrodes exhibited good electrocatalytic activity towards the oxidation of ascorbic acid (AA). Compared with the bare electrode, the oxidation peak potential negatively shifted about 350 mV (versus Ag/AgCl). Furthermore, the modified screen-printed carbon electrodes (SPCEs) could be used for the determination of ascorbic acid in real samples.

Extended topological indices and prediction of activities of chiral compounds

The activities/properties of two molecules with identical formula but different configuration states of the asymmetric atoms are different. Thus, usually the common topological indices are not suitable. In this study, the chiral topological indices were obtained by extending A(mi) indices suggested by our laboratory and molecular connectivity indices. The modified topologial indices have been used for the studies on D2 for dopamine receptor and a receptor activities of fourteen N-alkylated 3-(3-hydroxypyenyl)-piperidines. It has been observed that selected variables possess low correlations. The results obtained by using multiple regression analysis and artificial neural networks are satisfactory.

Fabrication of integrated microelectrodes for electrochemical detection on electrophoresis microchip by electroless deposition and micromolding in capillary technique

A new method for the fabrication of an integrated microelectrode for electrochemical detection (ECD) on an electrophoresis microchip is described. The pattern of the microelectrode was directly made on the surface of a microscope slide through an electroless deposition procedure. The surface of the slide was first selectively coated with a thin layer of sodium silicate through a micromolding in capillary technique provided by a poly(dimethylsiloxane) (PDMS) microchannel; this left a rough patterned area for the anchoring of catalytic particles. A metal layer was deposited on the pattern guided by these catalytic particles and was used as the working electrode. Factors influencing the fabrication procedure were discussed. The whole chip was built by reversibly sealing the slide to another PDMS layer with electrophoresis microchannels at room temperature. This approach eliminates the need of clean room facilities and expensive apparatus such as for vacuum deposition or sputtering and makes it possible to produce patterned electrodes suitable for ECD on microchip under ordinary chemistry laboratory conditions. Also once the micropattern is ready, it allows the researchers to rebuild the electrode in a short period of time when an electrode failure occurs. Copper and gold microelectrodes were fabricated by this technique. Glucose, dopamine, and catechol as model analytes were tested.

Evaluation of a sol-gel derived carbon composite electrode as an amperometric detector for capillary electrophoresis

In this paper, we report the construction and application of a sol-gel derived carbon composite electrode (CCE) as an amperometric detector for capillary electrophoresis. The electrochemical properties were characterized and compared with those of conventional carbon fiber and carbon paste electrode (CPE). Experimental results show that peak-to-peak noise of CCE was about 20% of CPE and electrode capacitance was comparatively low. When applied to the detection of dopamine and epinephrine, the optimal detection potential for CCE was 0.1 V lower than CPE under the same separation conditions; CCE with diameter of 75 and 100 mum could achieve a low detection limit of 3.10(-8) and 6.10(-8) M for the detection of epinephrine, which approaching that of the 33-mum diameter carbon fiber electrode. Also, the linearity for epinephrine at CCE was more than two orders of magnitude, which was slightly wider than that of carbon fiber electrode. Applications to real sample analysis were tested by the determination of betahistine dihydrochloride in tablets and human urine. Using CCE with diameter less than or equal to100 mum as an amperometric detector after capillary electrophoresis separation, a low detection limit and a wide linear range combined with excellent reproducibility were obtained. This CCE possesses of many advantages, namely, convenience, ease of fabrication, low cost and high stability.