荧光探针法研究石榴皮鞣质提取物对大鼠肝细胞DNA的保护作用

目的：荧光探针法研究石榴皮鞣质对溴化乙锭（EB）引起的大鼠肝细胞DNA损伤的保护作用。方法：培养大鼠肝细胞，抽提DNA，建立EB-DNA体系，研究3种样品溶液（石榴皮鞣质提取物，鞣花酸-没食子酸混合溶液，以及维生素C）与DNA分子的作用。根据作用常数的大小讨论了3种溶液及其各自的浓度对DNA的保护作用。并初步推断作用机制。结果：3种溶液对体系的荧光抑制率都随浓度增加而增加，其中石榴皮鞣质提取液组的抑制率可达到97％以上，鞣花酸-没食子酸组具有饱和性，维生素C组的抑制率最低。结论：石榴皮鞣质提取液与DNA分子可发生显著作用，对EB引起的大鼠肝细胞受损DNA有保护作用。     

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。     

不同浓度亚硫酸钠对HL-7702肝细胞活性的影响

目的为了对亚硫酸钠的细胞毒性研究提供实验参考,探讨不同浓度的亚硫酸钠(Na2SO3)对正常人肝细胞HL-7702的影响。方法通过不同浓度的Na2SO3对HL-7702染毒24h后,采用四甲基偶氮唑蓝微量酶比色法(MTT法)测定Na2SO3对肝细胞的活性抑制率。结果随着Na2SO3染毒剂量的增加,对细胞的活性抑制率逐渐增高,其中0.625mmol/L组和2.5mmol/L组与对阴性对照组相比,差异有统计学意义(P<0.05)。结论Na2SO3对肝细胞的活性有一定的抑制作用。     

盐酸异丙嗪与DNA相互作用的光谱学研究

目的 研究盐酸异丙嗪(PMT)与DNA的相互作用.方法 通过光谱法、热力学理论及黏度法进行研究.结果 盐酸异丙嗪与DNA相互作用形成络合物并淬灭其固有荧光,二者相互作用过程中ΔG0<0.二者结合常数随着温度的升高呈现下降趋势,且ΔS0>0,ΔH<0.氯化钠与磷酸二氢钠的加入对盐酸异丙嗪-DNA体系的荧光强度没有影响;随着盐酸异丙嗪浓度的增加,DNA-溴化乙锭体系的荧光强度逐渐减弱.DNA的相对黏度随着盐酸异丙嗪浓度的逐渐增大而显著升高.结论 DNA以静态方式淬灭盐酸异丙嗪固有荧光.二者之间的作用力主要以静电结合为主.盐酸异丙嗪与DNA相互作用模式为嵌插方式,并且盐酸异丙嗪可能以小沟方向插入DNA分子中.     

离子凝胶法制备水杨酸壳聚糖纳米粒

目的以壳聚糖为载体材料制备水杨酸壳聚糖纳米粒,并对其制备工艺及体系pH值对药物包封率的影响进行考察,初步探讨壳聚糖纳米粒的载药机制。方法以水杨酸为模型药物,采用离子凝胶法制备壳聚糖纳米粒,以包封率及粒径为指标,考察处方因素对纳米粒制备的影响。结果壳聚糖浓度、体系的pH值、药物质量浓度是影响制备工艺的主要因素;体系的pH值可显著提高壳聚糖纳米粒的包封率。结论药物与壳聚糖之间的离子相互作用较弱,并不是纳米粒载药的主要机制。     

羧甲基壳聚糖金属配合物的研制

应用水溶性的羟甲基壳聚糖与Ca^2 、Fe^2 、Zn^2 进行络合制备金属配合物,探讨反应时间、温度、羧甲基取代度、溶液离子强度、pH等反应条件对络合的影响,考察金属配合物的性质。结果表明：络合反应的最佳pH值为5－7;室温下反应10min络合量趋于饱和;羧甲基壳聚糖对各金属离子络合能力随羧甲基取代度的增大而增强,随着体系的离子强度增大而减弱。     

载ACE-shRNA pGenesil质粒与壳聚糖纳米粒的结合及释放实验

目的制备适当粒径的壳聚糖纳米粒,并连接上质粒,研究壳聚糖纳米粒对质粒DNA的结合能力及在体外的释放。方法采用离子交联法制备壳聚糖纳米粒,通过喷金电镜观察其大小、形态及分布;经琼脂糖凝胶电泳分析纳米载体与质粒DNA的结合能力;在4种不同pH值的磷酸盐缓冲液(PBS)中观察壳聚糖质粒纳米粒的释放情况;通过紫外分光光度计检测其包埋率及释放率。结果喷金电镜证实壳聚糖纳米粒分布均匀,呈近似球形,平均粒径约5nm;琼脂糖凝胶电泳结果显示壳聚糖纳米粒能有效地结合质粒,当纳米粒与质粒的比例为10∶10时包埋率达98.7%;壳聚糖质粒纳米粒的性质较稳定,在pH值<7.5的PBS溶液能够平稳释放100h左右。结论制备出适当粒径且分布均匀的壳聚糖纳米粒,能有效地结合质粒,并且能够持续平稳地释放。     

丹参素的抗癌活性研究

目的：建立体外抗癌天然药物筛选模型,评价丹参素的抗癌活性。方法：以遗传物质DNA为靶标,溴化乙锭（EB）为致癌物质,丹参素为试药,利用荧光光谱检测丹参素对EB-DNA体系的荧光猝灭效应;利用圆二色谱技术检测丹参素对EB-DNA体系的干扰作用。结果：丹参素能明显抑制EB-DNA体系的荧光强度,且具有浓度依赖性;丹参素能够有效阻断EB嵌入DNA的碱基对中,维持DNA分子的正常构象。结论：丹参素抑制致癌剂对DNA链的嵌合,从而起抗癌活性。该模型可应用于抗癌功效的天然药物的筛选中。     

离子凝胶法制备壳聚糖纳米粒的影响因素研究

目的 探讨离子凝胶法制备壳聚糖纳米粒(CS-NPs)的影响因素.方法 用碱降解法制备高脱乙酰度的壳聚糖(CS),并以之为材料,采用离子凝胶法制备CS-NPs,以微粒的平均粒径、分散度和Zeta电位为指标,考察CS及三聚磷酸钠(TPP)的质量浓度、CS/TPP质量比、CS溶液pH值和CS溶液温度对制备CS-NPs的影响....     

壳聚糖脱氧核糖核酸纳米球的制备及其相关特性研究

目的制备壳聚糖脱氧核糖核酸(DNA)纳米球并研究其理化性质和转染肝细胞系Hep G2和L 02 的活性。方法用绿色荧光蛋白（GFP）质粒做报告基因，GFP和壳聚糖通过复凝聚方法制备壳聚糖DNA纳米球，用扫描电镜观察其形态，激光粒度分析仪测定壳聚糖DNA纳米球粒度分布、表面电位，DNase Ⅰ保护实验研究壳聚糖DNA纳米球对包裹基因的保护作用，用体外基因转染实验定性评价纳米球的转染活性，MTT试验研究壳聚糖DNA纳米球对Hep G2和L 02的细胞毒作用。结果壳聚糖形成表面带正电荷的纳米球，保护DNA免受DNaseⅠ的降解。壳聚糖DNA纳米球作为非病毒载体转染肝细胞系，基因能有效表达。结论壳聚糖DNA纳米球作为非病毒载体转染肝细胞系有效，壳聚糖转染有细胞选择性。     

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.     

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.     

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.     

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.