三氧化二砷对胃癌细胞SGC7901/ADR GST-π和TopoⅡ表达的影响

目的探讨三氧化二砷(As2O3)对胃癌细胞SGC7901/ADR阿霉素(ADM)耐药性的逆转作用和对GSTπ和TopoⅡ表达的影响。方法用MTT法检测As2O3的非细胞毒性浓度和SGC7901/ADR细胞对ADM的敏感性,用流式细胞仪检测细胞内药物浓度及用免疫组织化学法检测细胞GSTπ和TopoⅡ的表达。结果与结论0.4~0.8μmol.L-1As2O3对耐药细胞SGC7901/ADR无明显毒性(P<0.01),As2O3可下调GSTπ表达,提高SGC7901/ADR细胞内ADM浓度,部分逆转SGC7901/ADR细胞对ADM的耐药性。     

黄芩苷逆转人肝癌细胞耐药株Bel-7402/ADM多药耐药性的相关机制研究

目的 考察黄芩苷对人肝癌耐药细胞Bel-7402/ADM 多药耐药性的逆转机制.方法 MTT法考察Baicalin对人肝癌多药耐药细胞的逆转作用.结果 Baicalin逆转Bel-7402/ADM多药耐药性的机制可能与抑制MDR1部分基因产物P-gp、MRP、GSH/GST的表达和诱导细胞凋亡有关.结论 Baicalin可能通过抑制MDR1部分基因产物P-gp、MRP、GSH/GST的表达和诱导细胞凋亡逆转Bel-7402/ADM的多药耐药性.     

胃癌多药耐药细胞中FOXC1的表达及其意义

目的探讨FOXC1在胃癌耐药细胞中的表达情况及对胃癌细胞药物敏感性的影响。方法采用q RT-PCR、Western Blot法检测胃癌多药耐药细胞SGC7901/ADR、SGC7901/VCR及亲本细胞SGC7901中FOXC1的表达;应用si RNA下调胃癌多药耐药细胞SGC7901/ADR、SGC7901/VCR中FOXC1的表达后以MTT法检测上述细胞IC50值的变化。结果 FOXC1在胃癌多药耐药细胞SGC7901/ADR、SGC7901/VCR表达显著高于亲本细胞SGC7901,当下调其表达后,SGC7901/ADR、SGC7901/VCR对多种化疗药物的敏感性显著升高。结论 FOXC1参与胃癌多药耐药过程,但其相关分子机制有待进一步深入研究。     

三氧化二砷对胃癌细胞SGC7901多药耐药的逆转作用及其机制

研究三氧化二砷(arsenic trioxide，As₂O₃)对胃癌细胞多药耐药的逆转作用及其机制。逐渐递增长春新碱(VCR)的浓度诱导胃癌细胞株SGC7901产生多药耐药性(SGC7901/VCR)。MTT法测定药物对肿瘤细胞的杀伤作用；Western blotting检测肿瘤细胞内P-糖蛋白(P-gp)、谷胱甘肽S-转移酶(GST-s)表达。结果表明，胃癌SGC7901/VCR细胞对长春新碱(VCR)、5-氟尿嘧啶(5-Fu)及表阿霉素的耐药倍数分别为16.56倍、2.69倍及13.05倍。经As₂O₃预处理24 h后，长春新碱、5-氟尿嘧啶及表阿霉素对SGC7901/VCR的耐药倍数显著下降(P<0.05)。SGC7901/VCR在静息时细胞内P-gp、GST-s蛋白表达显著高于SGC7901。而As₂O₃可使SGC7901/VCR细胞内P-gp、GST-s蛋白表达显著下降，但是对SGC7901无明显作用。从而证实As₂O₃部分逆转SGC7901/VCR的耐药性，其机制可能与P-gp、GST-s蛋白表达降低有关。     

五味子乙素对 MDR1介导的人骨肉瘤细胞 U-2 OS／ADR所致多药耐药性的逆转研究

目的：研究五味子乙素（schisandrin B,SchB）对人骨肉瘤细胞阿霉素耐药株U-2 OS／ADR多药耐药的逆转效果及逆转机制。方法采用浓度梯度递增法构建U-2 OS阿霉素耐药株U-2 OS／ADR;使用MTT法测定Sch B对于U-2 OS多药耐药逆转的影响,实时荧光定量PCR（ Q-PCR）检测SchB对MDR1基因转录的影响,流式细胞术检测细胞膜表面MDR1蛋白的表达,流式细胞术检测五味子乙素对罗丹明123外排和蓄积的影响,Western Blotting检测五味子乙素对PI3K／AKT通路的影响。结果五味子乙素能逆转U-2 OS／ADR细胞的多药耐药,并且能抑制MDR1基因的转录,降低膜表面MDR1蛋白的表达,增加细胞内罗丹明123的蓄积、减少外排,抑制U-2 OS／ADR细胞中PI3K／AKT通路的激活。结论五味子乙素具有强大的逆转人骨肉瘤细胞U-2 OS多药耐药的效果,其机制和下调耐药株的MDR1基因和蛋白水平,抑制PI3K／AKT通路激活有关。     

叶酸受体及二氢叶酸还原酶与人乳腺癌细胞MCF-7/ADR多药耐药的关系

目的以人乳腺癌多药耐药细胞系MCF-7/ADR及其敏感亲本系MCF-7为对象,探讨叶酸受体(FOLRα)及其下游基因二氢叶酸还原酶(DHFR)的表达与乳腺癌细胞多药耐药的关系。方法 MTT法测定阿霉素的细胞毒性作用及DHFR抑制剂对MCF-7/ADR细胞多药耐药的逆转作用;RT-PCR检测细胞FOLRα和DHFR mRNA的表达水平;免疫细胞化学检测FOLRα、P-gp的表达水平。结果 MCF-7细胞增殖速度快于MCF-7/ADR细胞,MCF-7细胞FOLRα mRNA转录水平较MCF-7/ADR细胞高,而MCF-7/ADR细胞DHFR mRNA较MCF-7细胞转录水平高;免疫细胞化学显示MCF-7细胞FOLRα的表达高于MCF-7/ADR细胞,而MCF-7/ADR细胞P-gp的表达较MCF-7细胞高;MCF-7/ADR对甲氨蝶啶无耐药性,甲氨蝶啶对MCF-7/ADR细胞多药耐药有逆转作用。结论 MCF-7/ADR细胞FOLRα的表达水平下调可能与细胞增殖水平有关,其下游基因DHFR表达水平与MCF-7/ADR细胞的MDR可能存在相关性。     

米尔贝逆转耐阿霉素人乳腺癌细胞多药耐药的作用

目的 探寻米尔贝类化合物尼莫克汀、米尔贝β1逆转人乳腺癌多药耐药细胞株(MCF-7/adr)多药耐药(multidrug resistance,MDR)的作用及机制.方法 采用MTT比色法测定细胞生长抑制率及耐药指数;高效液相色谱(HPLC)检测细胞内阿霉素(ADR)的积累变化;荧光分光光度仪检测罗丹明123(Rh123)在肿瘤细胞内的积累;通过RT-PCR与流式细胞仪检测MDR1基因与P-糖蛋白(P-gp)表达的变化.结果 5 μmol·L-1的尼莫克汀、米尔贝β1可明显增强MCF-7/adr对ADR的敏感性,增加细胞内ADR及Rh123的积累,且呈剂量依赖关系,不同程度降低MDR1和P-gp的表达.结论 尼莫克汀、米尔贝β1对MCF-7/adr的耐药有一定的逆转作用,且尼莫克汀效果好于米尔贝β1.     

补骨脂素逆转多药耐药细胞系K562/ADR耐药性研究

目的　研究补骨脂素对白血病细胞阿霉素耐药株(K5 6 2 /ADR)多药耐药 (multidrugresistance,MDR)性的逆转作用及其机制。方法　采用MTT法检测药物细胞毒性作用 ,高效液相色谱法检测细胞内阿霉素 (ADR)的浓度 ,流式细胞术测定细胞P 糖蛋白 (P gp)的表达。 结果　补骨脂素 (1～ 2 0 μmol·L-1)能不同程度地降低ADR对K5 6 2 /ADR细胞的IC50 。 2 0 μmol·L-1能显著提高ADR在K5 6 2 /ADR细胞内的浓度 ,降低K5 6 2 /ADR细胞P gp的表达。 结论　补骨脂素能逆转K5 6 2 /ADR细胞的MDR ,其机制与抑制P gp的功能及其表达 ,增加细胞内ADR的积累有关     

新型光敏剂光动力治疗耐药胃癌的实验研究

目的研究新型光敏剂DTP介导的光动力学治疗(PDT)对人长春新碱(vincristine,VCR)耐药胃癌细胞SGC7901/VCR的治疗作用,并揭示DTP-PDT与P-gp之间的关系及相关机制。方法 MTT法评价DTP-PDT对SGC7901/VCR细胞的杀伤作用及联合治疗作用;建立耐药细胞裸鼠模型,计算瘤体积,观察治疗效果;流式细胞术检测细胞凋亡及坏死情况;检测DTP-PDT后,细胞内单线态氧(~1O_2)产率;流式细胞术和qPCR技术分别检测MDR1 mRNA和P-gp表达。结果 DTP-PDT对SGC7901/VCR细胞及其裸鼠移植瘤均有明显杀伤作用,细胞死亡方式为凋亡;DTP-PDT后,细胞内~1O_2水平增加;DTP-PDT能够抑制耐药细胞MDR1 mRNA转录和P-gp表达,生育酚(α-tocopherol)可以减弱这种抑制;DTP-PDT与VCR合用对耐药细胞有协同治疗作用,生育酚可以减弱这种协同。结论 DTP-PDT产生的~1O_2可以抑制SGC7901/VCR生长,诱发细胞凋亡,而且能够抑制细胞表面P-gp的过表达,减少化疗药物外排,使DTP-PDT与VCR有协同治疗作用。     

抑制PI3K/PKB信号通路提高胃癌细胞化疗敏感性的研究

目的探讨磷脂酰肌醇3激酶(phosphatidylinositol 3-kinase,PI3K)抑制剂LY294002提高胃癌耐药细胞SGC7901/VCR和亲代细胞SGC7901对化疗药物敏感性的作用及其机制。方法MTT法分别检测胃癌细胞SGC7901和SGC7901/VCR对化疗药长春新碱(VCR)的敏感性;RT-PCR法和免疫细胞化学法检测LY294002处理前后多药耐药蛋白1(multidrug resistance protein-1,MDR1)和X染色体连锁的凋亡抑制蛋白(X-linked inhibitor of apoptosis,XIAP)基因和蛋白水平;Westernblot法检测LY294002处理前后细胞PKB总蛋白水平和磷酸化水平;并用流式细胞仪检测细胞的凋亡率。结果2×10-5mol·L-1 LY294002能明显增加SGC7901和SGC7901/VCR细胞对VCR的敏感性(P<0.01),其IC50分别由(0.20±0.03)和(8.09±0.60)mg·L-1降至(0.05±0.006)和(1.70±0.20)mg·L-1;降低细胞MDR1和XIAP的基因和蛋白水平;降低磷酸化PKB水平,而对其总蛋白水平无影响;LY294002联合VCR用药后细胞凋亡率明显高于单独VCR处理(P<0.01)。结论LY294002通过降低耐药基因MDR1和抗凋亡基因XIAP的表达,提高耐药和非耐药胃癌细胞对化疗药物的敏感性,此过程与抑制PI3K/PKB通路密切相关。     

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.