超广谱β-内酰胺酶SHV-5的基因重组表达及酶活性鉴定

目的对blaSHV-5进行基因重组表达，为建立SHV类β-内酰胺酶抑制剂筛选模型研究奠定基础。方法以产blaSHV-5肺炎克雷伯菌基因组DNA为模板，自行设计一对寡核苷酸引物，通过PCR扩增获得blaSHV-5基因片断，定向克隆入质粒载体pBK—CMV构建重组质粒，对重组质粒进行酶切鉴定和DNA测序鉴定，重组质粒转化大肠埃希菌XL1-Blue MRF’后，Nitrocefin显色结合SDS—PAGE分析目的基因在大肠埃希菌中的表达及其酶活性。结果PCR扩增获得了大小约为900bp的DNA条带，定向克隆入质粒载体pBK—CMV后筛选到大小约为5．4kb的重组质粒，SacⅠ和EcoRⅠ双酶切后可切下大小约900bp的插入片段，DNA测序发现插入片断的基因序列与GenBank中肺炎克雷伯菌基因序列完全一致，重组质粒转化大肠埃希菌XL1-Blue MRF＇后可表达分子量约为31500的重组蛋白。重组菌裂解液对nitrocefin显示出较强水解活性。结论超广谱β-内酰胺酶SHV-5在大肠埃希菌XL1-Blue MRF＇中实现了基因重组表达。为进一步进行酶的纯化等相关后续研究奠定了基础。     

肝靶向药物的研究进展

综述肝靶向药物的研究进展.治疗性的肝靶向药物有毫微粒及微球制剂、免疫导向药物、糖蛋白受体导向药物、信号靶向药物、肝靶向降胆固醇药物、抗疟药及促骨骼生长药等;诊断性的肝靶向药物有磁性毫微粒、无唾液酸糖蛋白受体介导的肝靶向药物等.肝靶向药物的研究开发,为肝脏疾病及其相关疾病的诊断和治疗开辟了广阔的前景.     

乳糖-聚赖氨酸复合物对肝细胞导向能力的研究

目的 :利用肝细胞膜存在的去唾液酸糖蛋白受体 ,合成一种能够携带目的DNA分子特异性富集到肝组织中的载体。方法 :在弱碱性溶液中 ,在氰基硼氢化钠作用下 ,通过还原氨化法进行乳糖 (Lac)与聚赖氨酸 (PLL)的共价连接 ,SephadexG 10分离纯化产物 ;采用真核细胞表达基因 β 半乳糖苷酶报道基因 ,在细胞培养中和小鼠体内观察乳糖 聚赖氨酸复合物 (Lac PLL)对肝细胞的导向能力。结果 :Lac在氰基硼氢化钠作用下能有效地结合到PLL分子上 ,Lac与PLL的摩尔比为 16∶1;Lac PLL复合物在体外能够与DNA分子形成稳定偶联物 ,使其所偶联的DNA分子有效地进入到肝癌细胞 ,并使相应基因在细胞中表达。小鼠尾静脉注射DNA/Lac PLL偶联物10 μg后 ,DNA能有效地在肝组织中富集并在肝细胞中表达。结论 :Lac PLL是一种有效的对目的DNA分子具有肝细胞特异性导向能力的载体。     

蜂毒素对人肝癌细胞中HMGB1及VEGF-C表达的影响

目的观察蜂毒素对人肝癌细胞株HepG2中高迁移率族蛋白B1(high mobility group box1,HMGB1)及血管内皮生长因子C(vascular endothelial growth factors C,VEGF-C)表达的影响,探讨其抑制肝癌细胞的作用机制。方法肝癌细胞HepG2体外培养,经蜂毒素处理后,采用四甲基偶氮唑蓝(MTT)法了解蜂毒素对肝癌细胞增殖的影响,用Western-blotting、qRT-PCR方法检测HMGB1、VEGF-C的表达。结果蜂毒素在体外能够抑制肝癌细胞的增殖活性;Western-blotting结果显示,蜂毒素可抑制HMGB1的表达,且呈浓度依赖性,但对VEGF-C的蛋白表达无明显影响;qRT-PCR结果显示,蜂毒素在mRNA水平均具有抑制HMGB1、VEGF-C表达的作用。结论蜂毒素可降低肝癌细胞的增殖活性,并可能通过HMGB1、VEGF-C的表达发挥抗肝癌作用。     

去唾液酸糖蛋白受体介导的肝靶向研究进展

目的 介绍去唾液酸糖蛋白受体(asialoglycoprotein receptor,ASGPR)介导的药物和基因肝靶向作用和机制,及其在治疗肝癌和乙型肝炎实验研究方面的最新进展。方法 查阅和选取针对性强、相关度高的文献,总结和归纳ASGPR介导的药物和基因肝靶向用于治疗肝癌和乙型肝炎的最新研究进展。结果 ASGPR是肝细胞的一种重要且高效的内吞受体,可用于介导药物和基因的肝靶向递送。结论 ASGPR介导的药物和基因肝靶向有望成为肝癌和乙型肝炎治疗的有效手段。     

蜂毒肽融合蛋白在裂殖酵母中的表达研究

将抗菌肽之一的蜂毒溶血肽(Melittin)基因序列定向克隆到表达载体pESP-2中,构建GST-Melittin融合蛋白。利用载体上严格受硫胺素浓度调控的启动子Pnmtl,采用先扩大培养后诱导表达的两步培养法,实现了融合蛋白在裂殖酵母Schizosaccharomyces Pombe中的异源表达。然后通过GST亲和层析法一步纯化得到融合肽。研究中1L培养液收集到约5g鲜活酵母菌,纯化得到400μg融合蛋白,融合蛋白经SDS-PAGE和Western blot验证,表明蜂毒肽融合蛋白已在裂殖酵母中高效的表达,并可以通过GST亲和层析法得到有效纯化。初步的活性实验证明所获得Melittin蛋白对Escherichia Coli DH5α菌种有良好的抑菌效果。     

脂质体肝实质细胞靶向性研究

目的 脂质体经配体修饰后介导受体细胞,以达靶向给药。方法 肝实质细胞上无唾液酸糖蛋白受体(ASGP-R)的配体无唾液酸胎球蛋白(AF)修饰脂质体得AF-SSL。将ASGP-R重组于脂质双分子膜(BLM)得ASGP-R-BLM,与AF-SSL相互作用,监测BLM膜电参数变化,确定受体-配体间识别反应;用3H标记方法测AF-SSL与肝实质细胞在体内外靶向性;将AF-SSL包抗癌药阿霉素(ADM),考察其抗癌药效。结果ASGP-R-BLM稳定时间随AF-SSL加入量增加而缩短,表现出明显的量效关系,证明在ASGP-R-BLM与AF-SSL之间有特异识别反应;体外AF-SSL与肝实质细胞结合率明显高于无AF修饰脂质体SSL(在第10和90 min时P<0.05,在第30和60 min时P<0.01);抗肝癌疗效,AF-SSL组大鼠存活期显著长于无AF修饰组,且对心、肾、肺的毒副作用小。结论配体修饰脂质体达到主动靶向对应受体细胞是可行的,本文为脂质体细胞水平靶向给药提供依据。     

肝靶向药物研究——模型化合物NGA-去甲替林的合成及其趋肝性

肝细胞膜上的肝结合蛋白(HBP)是无唾液酸糖蛋白的受体。作者合成了无唾液酸糖蛋白的类似物—半乳糖新糖白蛋白(NGA)并用其作为肝靶向药物的载体,采用琥珀酸酐法与药物去甲替林(NT)偶联得NGA-NT。以此作模型化合物,经~(99m)Tc标记后的动物放射显像及HPLC检测结果,说明NGA-NT在血中稳定,在肝脏降解释出NT,具有显著的趋肝性。     

洛铂对肝癌细胞HepG2的放疗增敏效应

目的 探讨洛铂对肝癌细胞的放疗增敏效应.方法 用MTT法确定洛铂对肝癌细胞株HepG2半数抑制浓度(IC50),流式细胞仪检测1/4 IC50、1/8 IC50洛铂对HepG2细胞周期、凋亡的影响,蛋白免疫印迹检测凋亡相关蛋白Bcl-2、Bax、Caspase-3的表达,细胞克隆形成实验研究洛铂对HepG2的放射增敏比.结果 洛铂对肝癌细胞株HepG2细胞毒作用呈剂量依赖性,半数抑制浓度为1.85μg/ml,不同浓度洛铂组(1/4 IC50组、1/8 IC50组)均观察到HepG2细胞凋亡和G2/M期阻滞明显增加(P＜0.05);两组洛铂干预组肝癌细胞Bcl-2表达下降,Bax、Caspase-3表达水平升高;洛铂对肝癌细胞HepG2的放疗增敏比分别是1.12、1.28.结论 洛铂具有放射增敏作用;其机制可能与促进肝癌细胞凋亡以及细胞G2/M期阻滞相关.     

肝靶向水溶性药物纳米化的研究进展

目前,水溶性药物的肝靶向性研究一般有网状内皮细胞吞噬的被动靶向和基于肝受体识别的主动靶向。被动靶向主要依赖于微粒的大小及表面性质,主动靶向利用分子和受体的特异性配体的识别,肝实质细胞中的去唾液酸糖蛋白作为肝靶向的有效靶点而受到广泛研究。主动靶向制剂是利用肝受体的识别,使药物具有高度靶向性、缓控释性;被动靶向主要是利用纳米粒的小尺寸效应使其具备奇特的物理、化学特性。药物适合于制成哪种类型,要根据靶向部位要求和药物理化性质具体而定。     

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.     

Synthesis,Cytotoxicity and Antileishmanial Activity of Some N-(2-(indol-3-yl)ethyl)-7-chloroquinolin-4-amines

We report herein the condensation of 4,7-dichloroquinoline (1) with tryptamine (2) and D-tryptophan methyl ester (3) . Hydrolysis of the methyl ester adduct (5) yielded the free acid (6) . The compounds were evaluated in vitro for activity against four different species of Leishmania promastigote forms and for cytotoxic activity against Kb and Vero cells. Compound (5) showed good activity against the Leishmania species tested, while all three compounds displayed moderate activity in both Kb and Vero cells.     

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.