大黄素电化学性质的研究

目的:研究了大黄素的电化学性质以及大黄素与牛血清白蛋白(BSA)相互作用的电化学行为。方法:采用循环伏安法和差分脉冲伏安法对大黄素进行电化学行为的研究,并在不同pH值下进行线形扫描实验;同时应用紫外-可见分光光度法对大黄素与牛血清白蛋白的结合情况进行了研究。结果:大黄素在-0.522V处出现一个明显的还原峰;大黄素与牛血清白蛋白结合生成了一种非电活性的超分子化合物,并对结合反应的机理进行了探讨。结论:大黄素的还原峰电流与扫描速率呈简单线性关系。大黄素与牛血清白蛋白结合形成非电活性的超分子化合物导致大黄素氧化还原峰电流降低,峰电位基本不变,峰电流的下降值同所加入的BSA浓度在一定范围内呈线性关系。     

线性扫描伏安法测定克拉霉素含量

目的研究克拉霉素(CAM)在多壁碳纳米管修饰玻碳电极上的电化学行为,建立一种直接测定CAM的电化学分析方法。方法采用循环伏安法研究CAM在修饰电极上的电化学行为,以线性扫描伏安法对其含量进行测定。结果在优化实验条件下,氧化峰电流与CAM浓度在5.0×10-7~1.0×10-4mol/L范围呈现良好的线性关系,检出限为1.0×10-7mol/L;对5.0×10-6mol/L CAM溶液平行测定10次的RSD为2.6%。结论该方法简单、快速、灵敏,可用于CAM胶囊的质量分析。     

利用聚茜素红薄膜修饰电极测定阿昔洛韦

目的利用聚茜素红薄膜修饰电极(PARSE)对阿昔洛韦(ACV)的电催化作用,建立了一种新的对ACV含量进行定量分析的电化学分析方法。方法在0.05mol/L PBS(pH=6.86) 0.3mol/L NaC l体系中,利用PARSE为工作电极,以100mV/s的扫描速率在0~1.2V电位范围内进行循环伏安扫描,根据循环伏安图上氧化峰电流的大小,对ACV进行定量分析。结果ACV的浓度在5.0×10-6~6.8×10-4mol/L范围内与峰电流呈良好的线性关系,r=0.9998,检出限为8.0×10-7mol/L。平行实验的RSD=0.9%(n=10),回收率为94.6%~104.3%。结论该法简单、灵敏、可靠,用于药剂样品中ACV的含量分析,得到满意结果。     

甲硝唑片及其伏安行为的示波极谱法测定

用示波极谱法测定甲硝唑片,并对其伏安行为进行了研究。结果表明,在pH8的Britton-Robinson缓冲液和1.5mol/L氯化钾溶液组成的底液中,甲硝唑在-0.54V(vs. SCE)出现了一个极谱还原峰,峰电流与其溶液浓度在0.4～1.5mg/L范围内呈良好线性关系(r=0.9975),检测限为1.85×10-6g/L。并用循环伏安法、脉冲极谱法研究了甲硝唑还原峰的电流性质,发现电极反应是完全不可逆的,存在吸附性。     

多壁碳纳米管修饰电极测定盐酸环丙沙星

目的研究盐酸环丙沙星(CPLX)在多壁碳纳米管修饰玻碳电极上的电化学行为,建立一种直接测定CPLX的电化学分析方法。方法循环伏安法与线性扫描伏安法等电化学方法。结果在优化实验条件下,氧化峰电流与CPLX浓度在1.0×10-7~7.5×10-5mol/L范围呈现良好的线性关系,检出限为3.0×10-8mol/L。对5.0×10-5mol/L     

复方二仙汤中盐酸小檗碱及总生物碱的含量测定

目的:建立测定雷贝拉唑含量的新方法.方法:采用碳糊电极阳极吸附伏安法,在1.8 mol/L H2SO4底液中,通过富集用碳糊电极阳极吸附伏安法研究雷贝拉唑的电化学行为.结果:阳极峰电位为0.498V(vs.SCE),峰电流与雷贝拉唑的浓度在4.15×107～3.37×10-6mol/L范围内呈良好的线性关系,检出限为6.705×10-11mol/L.结论:本方法简便准确,适用于雷贝拉唑的含量测定.     

泰乐星在碳糊电极上的伏安行为研究及应用

目的 研究表面活性剂增敏作用下泰乐星(TLS)在碳糊电极(CPE)上的电化学行为,建立一种测定TLS的电化学分析方法 .方法 用循环伏安法(cyclic voltammetry,CV)和线性扫描伏安法(linear sweep voltammetry,LSV)探讨了TLS在CPE上的电化学行为及其影响因素.结果 阴离子表面活性剂十二烷基苯磺酸钠(SDBS)存在下TLS在CPE上有一显著的不可逆氧化峰,峰电位(Ep)为0.735V.结论 TLS氧化峰电流与其浓度在1.2×10-5～1.0 × 10-3mol/L范围内呈良好的线性关系,r=0.9974,检出限1.7×10-7mol/L,以此建立TLS含量的电化学分析方法 .测定结果 RSD1.6～2.4%,加样回收率98.6%～101.1%.该方法 简便快捷,测定结果 令人满意.     

N-乙酰-5-羟色胺的电化学检测研究

采用方波溶出伏安法(OSWSV),建立了N-乙酰-5-羟色胺的—种新型快速、灵敏的测定体系。实验研究了富集条件、pH值对方波溶出伏安法对N-乙酰-5-羟色胺的影响。在pH=9.33的硼砂-氢氧化钠缓冲液中,N-乙酰-5-羟色胺在约0.2V(vs.Ag/AgCl)电位处产生一个阳极氧化峰,峰电流与浓度在1.0×10-7~1.0×10-4mol.L-1范围内成线性关系,N-乙酰-5-羟色胺检测限为1.2×10-8mol.L-1。进行尿样样品测定,回收率为81.8%,结果良好。     

盐酸异丙嗪在聚中性红修饰碳糊电极上的电化学行为及测定

目的:研究盐酸异丙嗪在聚中性红修饰碳糊电极(PNR/CPE)上的电化学行为,建立一种修饰电极测定盐酸异丙嗪含量的新方法。方法:采用循环伏安法(CV)研究碳糊电极(CPE)上电聚合制备聚中性红膜的最佳聚合条件及盐酸异丙嗪在该修饰电极上的电化学行为,以方波伏安法(SWV)对盐酸异丙嗪进行含量分析。结果:中性红在碳糊电极上聚合效果很好,对盐酸异丙嗪有着良好的电催化氧化作用,与CPE相比,盐酸异丙嗪在PNR/CPE上的氧化峰电流增加约5倍,其峰电流与浓度在1.0×10-6～1.0×10-3mol.L-1范围内呈现良好的线性关系,检出限为2.0×10-7mol.L-1。结论:该法灵敏度高,可用于盐酸异丙嗪片的测定。     

光谱学手段对芦荟大黄素潜在毒副作用的研究

目的研究芦荟大黄素与DNA的相互作用和结合方式,从光谱学的角度考察芦荟大黄素的潜在基因毒性。方法采用荧光共振散射手段检测1.0 ml的0.756×10-5 mol/L DNA溶液分别加入0.5、1.0和1.5ml的1×10-4mol/L芦荟大黄素溶液,30 min后图谱的变化,并与相同条件下1×10-4 mol/L EB比较。选择480 nm激发波长,扫描纪录495～650 nm波长范围内1.00 ml 1×10-4 mol/L芦荟大黄素溶液加入一定量的DNA溶液后的荧光发射光谱,并通过荧光加强型理论公式计算结合常数。结果芦荟大黄素与DNA在308和537nm处有较强的共振散射峰;芦荟大黄素在545 nm附近有荧光激发峰,其强度随着DNA浓度增大而增强,通过公式计算得出芦荟大黄素与DNA的结合常数为1.43×106 L/mol。结论在该试验条件下,芦荟大黄素与DNA之间存在着嵌插作用,具有潜在基因毒性。     

Efficacy of gut lavage,hemodialysis, and hemoperfusion in the therapy of paraquat or diquat intoxication

Clinical and in vitro investigations were carried out to test the efficacy of gut lavage, hemodialysis, and hemoperfusion in the treatment of poisoning with paraquat or diquat. In a patient suffering from diquat intoxication 130 times more diquat was removed by gut lavage 30 h after ingestion than was removed by complete aspiration of the gastric contents.Determination of in vitro clearances for paraquat and diquat by hemodialysis showed that, at serum concentrations of 1–2 ppm, such as are frequently encountered in poisoning in man, toxicologically relevant quantities of herbicide cannot be removed from the body. At a concentration of 20 ppm, on the other hand, hemodialysis proved to be effective, the clearance being 70 ml/min at a blood flow rate of 100 ml/min. The efficacy of hemoperfusion with coated activated charcoal was on the whole better. Especially at concentrations around 1–2 ppm, the clearance values for hemoperfusion were some 5–7 times higher than those for hemodialysis.In a patient suffering from paraquat poisoning, both hemodialysis as well as hemoperfusion were carried out. The in vitro results could be confirmed: At serum concentrations of paraquat less than 1 ppm no clearance could be obtained by hemodialysis while by hemoperfusion with activated charcoal quite high clearance values were measured and the serum level dropped down to zero.

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Zusammenfassung Klinische Untersuchungen und Laboratoriumsversuche wurden durchgeführt, um die Wirksamkeit von Darmspülung, Hämodialyse und Hämoperfusion bei Paraquat- und Deiquat-Vergiftungen zu prüfen.Bei einem Patienten wurde 30 Std nach Deiquat-Aufnahme durch Darmspülung 130mal mehr Deiquat entfernt als durch vollständige Aspiration des Mageninhaltes. In vitro-Versuche ergaben, daß bei Blutserumkonzentrationen von 1–2 ppm, die bei Vergiftungen oft gemessen werden, durch Hämodialyse keine toxikologisch relevanten Paraquat- oder Deiquat-Mengen entfernt werden können. Dagegen erwies sich die Hämodialyse bei 20 ppm und einer Blutumlaufgeschwindigkeit von 100 ml/min mit einer Clearance von 70 ml/min als wirksam. Die Hämoperfusion mit beschicheter Aktivkohle war in diesen Versuchen aber eindeutig überlegen, denn insbesondere bei Konzentrationen um 1–2 ppm waren die Clearance-Werte 5–7mal höher als bei der Hämodialyse.Die in vitro-Ergebnisse wurden bei einem Patienten mit einer Paraquat-Vergiftung bestätigt: Bei Konzentrationen unter 1 ppm war die Hämodialyse wirkungslos, während durch Hämoperfusion relativ hohe Clearance-Werte erreicht wurden, so daß der Serumspiegel rasch unter die Nachweisgrenze abfiel.

     

In vitro studies on sterically stabilized liposomes (SL) as enzyme carriers in organophosphorus (OP) antagonism

This study describes a new approach for organophosphorous (OP) antidotal treatment by encapsulating an OP hydrolyzing enzyme, OPA anhydrolase (OPAA), within sterically stabilized liposomes. The recombinant OPAA enzyme was derived from Alteromonas strain JD6. It has broad substrate specificity to a wide range of OP compounds: DFP and the nerve agents, soman and sarin. Liposomes encapsulating OPAA (SL)* were made by mechanical dispersion method. Hydrolysis of DFP by (SL)* was measured by following an increase of fluoride ion concentration using a fluoride ion selective electrode. OPAA entrapped in the carrier liposomes rapidly hydrolyze DFP, with the rate of DFP hydrolysis directly proportional to the amount of (SL)* added to the solution. Liposomal carriers containing no enzyme did not hydrolyze DFP. The reaction was linear and the rate of hydrolysis was first order in the substrate. This enzyme carrier system serves as a biodegradable protective environment for the recombinant OP-metabolizing enzyme, OPAA, resulting in prolongation of enzymatic concentration in the body. These studies suggest that the protection of OP intoxication can be strikingly enhanced by adding OPAA encapsulated within (SL)* to pralidoxime and atropine.     

Aquatic Insects and Trace Metals: Bioavailability,Bioaccumulation, and Toxicity

Abstract

The uptake of metals from food and water sources by insects is thought to be additive. For a given metal, the proportions taken up from water and food will depend both on the bioavailable concentration of the metal associated with each source and the mechanism and rate by which the metal enters the insect. Attempts to correlate insect trace metal concentrations with the trophic level of insects should be made with a knowledge of the feeding relationships of the individual taxa concerned. Pathways for the uptake of essential metals, such as copper and zinc, exist at the cellular level, and other nonessential metals, such as cadmium, also appear to enter via these routes. Within cells, trace metals can be bound to proteins or stored in granules. The internal distribution of metals among body tissues is very heterogeneous, and distribution patterns tend to be both metal and taxon specific. Trace metals associated with insects can be both bound on the surface of their chitinous exoskeleton and incorporated into body tissues. The quantities of trace meals accumulated by an individual reflect the net balance between the rate of metal influx from both dissolved and particulate sources and the rate of metal efflux from the organism. The toxicity of metals has been demonstrated at all levels of biological organization: cell, tissue, individual, population, and community. Much of the literature pertaining to the toxic effects of metals on aquatic insects is based on laboratory observations and, as such, it is difficult to extrapolate the data to insects in nature. The few experimental studies in nature suggest that trace metal contaminants can affect both the distribution and the abundance of aquatic insects. Insects have a largely unexploited potential as biomonitors of metal contamination in nature. A better understanding of the physico-chemical and biological mechanisms mediating trace metal bioavailability and exchange will facilitate the development of general predictive models relating trace metal concentrations in insects to those in their environment. Such models will facilitate the use of insects as contaminant biomonitors.     

Steroidal sapogenin contents in some domestic plants

In order to find out the values of the steroid resources for the future use. the compositions and contents of steroidal sapogenins from 13 domestic plants have been investigated. As a result,Dioscorea nipponica, D. quinqueloba andSmilax china were found to have large amount of diosgenin. And pennogenin inTrillium kamtschaticum andParis verticillata, yuccagenin inAllium fistulosum, hecogenin inAgave americana and neochlorogenin inSolanum nigum were appeared to be major steroidal sapogenins.     

Alzheimer’s disease – current trends in basic and clinical research. Highlights from the 16th ECNP

Advances in the molecular biological knowledge of neuronal nicotinic acetylcholine receptors (nAChRs) have led to a growing interest by the pharmaceutical industry in the development of novel compounds that selectively modulate nAChR function. The ability of (-)-nicotine, an activator of nAChRs, to enhance attentional aspects of cognition in animals and humans, to exert neuroprotective and anxiolytic-like effects, and presumably to mediate the negative correlation between smoking and Alzheimer's (and Parkinson's) Disease, has focused interest on the potential therapeutic utility of modulators of nAChR function for treatment of some of the deficits associated with these progressive, neurodegenerative conditions. Numerous compounds are known which activate nAChRs and which might serve as lead compounds toward the development of such agents. The pharmacologic diversity of neuronal nAChR subtypes suggests the possibility of developing selective compounds which would have more favourable side-effect profiles than existing agents. This broader class of agents, collectively called cholinergic channel modulators (ChCMs), is anticipated to encompass compounds which would have more favourable side-effect profiles than existing agents, which generally exhibit low selectivity. This selectivity may be achieved by preferentially activating some subtypes of nAChRs (i.e., Cholinergic Channel Activators, ChCAs) or inhibiting the function of other subtypes (Cholinergic Channel Inhibitors, ChCIs). An overview of the biology of nAChRs and the rationale for the use of ChCMs for the treatment of dementia related to neurodegenerative diseases are presented, followed by a discussion of lead compounds and compounds under consideration for clinical evaluation.