反义抑制miR-222表达对替莫唑胺所致神经胶质瘤细胞DNA损伤作用的影响

目的探讨miR-222低表达的神经胶质瘤细胞(T98G-miR-222-)对替莫唑胺(TMZ)的DNA损伤反应。方法运用脂质体Lipofectamine 2000将anti-miR-222和anti-NC分别转染至T98G细胞后,分别用0、100、200、400和800μmol/L的TMZ处理转染T98G细胞,运用Northern blot等检测miR-222表达水平;以单细胞凝胶电泳(SCGE)检测DNA损伤指标彗性尾长。结果 TMZ引起T98G细胞DNA损伤指标彗星尾长增加,且有一定的剂量效应关系;anti-miR-222处理T98G细胞的DNA损伤指标彗星尾长显著高于同一剂量处理的anti-NC细胞。结论反义抑制miR-222表达可增强替莫唑胺所致神经胶质瘤细胞DNA损伤。     

替莫唑胺和Bcl-2 siRNA对人胶质瘤U251细胞生长的影响

目的 探讨联合应用Bcl-2 siRNA和替莫唑胺(TMZ)能否有效提高TMZ对人胶质瘤U251细胞生长的抑制作用.方法 应用转染试剂LipofectaminTm2000将Bcl-2 siRNA转入U251细胞,同时加入TMZ联合培养.24 h后验证Bcl-2基因沉默效应,并检测U251细胞增殖、凋亡、侵袭和细胞线粒体膜电位变化.结果 Bcl-2 siRNA明显抑制U251细胞Bcl-2基因的表达;联合应用TMZ和Bcl-2 siRNA有效抑制人胶质瘤U251细胞生长,诱导凋亡,同时降低U251细胞线粒体膜电位(P＜0.05).结论 联合TMZ和Bcl-2 siRNA可能通过改变神经胶质瘤细胞线粒体膜电化水平,有效提高U251细胞对TMZ敏感性.     

反义抑制miR-222表达对替莫唑胺所致神经胶质瘤细胞DNA损伤作用的影响北大核心CSCD

目的探讨miR-222低表达的神经胶质瘤细胞(T98G-miR-222-)对替莫唑胺(TMZ)的DNA损伤反应。方法运用脂质体Lipofectamine 2000将anti-miR-222和anti-NC分别转染至T98G细胞后,分别用0、100、200、400和800μmol/L的TMZ处理转染T98G细胞,运用Northern blot等检测miR-222表达水平;以单细胞凝胶电泳(SCGE)检测DNA损伤指标彗性尾长。结果 TMZ引起T98G细胞DNA损伤指标彗星尾长增加,且有一定的剂量效应关系;anti-miR-222处理T98G细胞的DNA损伤指标彗星尾长显著高于同一剂量处理的anti-NC细胞。结论反义抑制miR-222表达可增强替莫唑胺所致神经胶质瘤细胞DNA损伤。     

白藜芦醇通过BRD4调控Wnt/β-catenin通路逆转胶质瘤细胞替莫唑胺耐药的机制研究

目的 探究白藜芦醇（RES）逆转胶质瘤细胞替莫唑胺（TMZ）耐药的作用是否与通过溴结合域蛋白4（BRD4）调控Wnt/β-链蛋白（β-catenin）通路有关。方法 取人神经胶质瘤TMZ低敏细胞株（U138）、高敏细胞株（U251）、耐药株（T98G）,Western blot法检测3种细胞株中BRD4、Wnt3a、β-catenin、TMZ耐药蛋白（MGMT）蛋白表达。取T98G细胞株分为对照1组（添加100 μmoL/L TMZ）、RES1组（添加50 μmoL/L RES）、RES+TMZ（添加100 μmoL/L TMZ和50 μmoL/L RES）组,用CCK-8法、流式细胞术检测各组细胞增殖、凋亡情况;Western blot法检测各组BRD4、Wnt3a、β-catenin、MGMT蛋白表达。为分析BRD4过表达对TMZ耐药性的影响,在添加100 μmoL/L TMZ的基础上,转染BRD4过表达质粒（pcDNA BRD4）或加入50 μmoL/L RES分别作为pcDNA NC组、pcDNA BRD4组、RES2组、RES+pcDNA BRD4组。为验证BRD4对Wnt3a/β-catenin通路的调控作用,在添加100 μmoL/L TMZ的基础上,加入BRD4抑制剂JQ1和Wnt3a/β-catenin通路激活剂LiCl,分为对照2组、JQ1组、JQ1+LiCl组。将T98G细胞接种于裸鼠左肩胛区,给予RES、TMZ和（或）JQ1治疗,检测瘤体中Ki67,BRD4、MGMT及Wnt3a/β-catenin蛋白表达。结果 与U251细胞相比,U138、T98G中BRD4、Wnt3a、β-catenin及MGMT表达均依次升高（P<0.05）。与对照1组相比,RES干预可抑制T98G细胞BRD4、Wnt3a/β-catenin、MGMT蛋白表达及增殖,促进凋亡,逆转细胞的耐药性（P<0.05）。pcDNA BRD4可逆转RES的抗增殖、促凋亡等上述作用。BRD4抑制剂JQ1可抑制T98G细胞BRD4、Wnt3a/β-catenin、MGMT蛋白表达及增殖,促进凋亡（P<0.05）;LiCl可逆转JQ1的抗增殖、促凋亡作用。RES单独或与JQ1联合治疗,可激活TMZ对瘤体内Wnt3a/β-catenin通路、MGMT表达和细胞增殖的抑制作用（P<0.05）。结论 RES可能通过下调BRD4,进而抑制Wnt3a/β-catenin通路活化,实现对胶质瘤T98G细胞TMZ耐药性的逆转。     

胶质瘤U251细胞化疗过程中MGMT表达改变与耐药的关系

目的探讨胶质瘤U251细胞中MGMT表达与卡莫司汀（BCNU）和替莫唑胺（TMZ）化疗耐药的关系。方法细胞生长情况用MTT进行评估,细胞周期采用流式细胞仪检测,MGMT表达用western-blot检测。结果 U251细胞对BCNU和TMZ存在耐药现象。在化疗过程中,处于G0/G1期细胞比例明显增加,MGMT表达无显著变化。结论利用BCNU和TMZ对U251进行化疗过程中,不能通过消耗MGMT,来达到逆转耐药现象的目的 。     

乙酰胆碱酯酶抑制剂他克林和多奈哌齐抗星形孢菌素致凋亡作用的比较

目的用星形孢菌素(STS)诱导NG108-15和HeLa细胞凋亡,观察他克林和多奈哌齐是否具有抗凋亡作用。方法MTT测定分析细胞损伤状况;相差显微镜和Hoechst 33342染色观察细胞及胞核形态;DNA提取及琼脂糖凝胶电泳观察凋亡特征性梯带;免疫印迹分析Bcl-2和Bax的表达水平。结果经0.1 mmol·L^-1他克林预处理后,由STS诱导的NG108-15细胞凋亡受到明显抑制。多奈哌齐预处理无保护作用。免疫印迹表明他克林可显著抑制Bax的表达,同时还可促进Bcl-2的表达。多奈哌齐和他克林预处理对STS诱导的HeLa细胞损伤无明显的保护作用。结论 他克林的抗凋亡作用与AChE抑制作用似乎没有明显关联。他克林对STS损伤的保护作用有细胞选择性。     

人参皂苷Rg1对PC12细胞凋亡保护作用的可能机制

目的探讨人参皂苷Rg1对多巴胺诱导PC12细胞凋亡的保护作用及其机制.方法用流式细胞仪检测PC12细胞的凋亡率及Bcl-2和Bax蛋白表达率,RT-PCR分析bcl-2和baxmRNA表达水平,荧光分光光度计法检测CPP32活力.结果经10μmol·L^-1Rg1预处理后,由多巴胺诱导的PC12细胞凋亡受到明显的抑制.同时,Bcl-2蛋白和mRNA表达增加,Bax蛋白和mRNA表达减少,CPP32活力明显下降.结论Rg1可抑制多巴胺诱导的PC12细胞凋亡,其作用机制可能通过调节Bcl-2与Bax蛋白的比值和抑制CPP32的激活而起作用.     

替莫唑胺在恶性胶质瘤治疗方面的研究进展

恶性胶质瘤是常见的颅内原发性肿瘤,替莫唑胺（TMZ）是一种临床上用于治疗恶性神经胶质瘤的DNA-烷化剂药物。DNA修复蛋白O6-甲基鸟嘌呤-DNA-甲基转移酶（O6-methylguanine-DNA methyltransferase,MGMT）的表观遗传沉默是TMZ治疗恶性胶质瘤的重要靶点,因此,对于缺乏MGMT启动子甲基化的肿瘤患者TMZ不能发挥有效的治疗效果。同时,研究表明通过基因治疗降低MGMT水平可显著增加TMZ的治疗作用,降低治疗抗性。因此,本研究对TMZ在恶性胶质瘤治疗的作用机制和化学抗性进行综述,以期为今后TMZ的临床应用提供理论依据。     

脑肿瘤新化疗药物——替莫唑胺

用于原发性脑肿瘤化学治疗的新药替莫唑胺（temozolomide，TMZ，商品名Temodol，泰道）是一种新型烷化剂，无需酶的催化即自发降解，形成的降解产物可造成DNA损伤，诱导细胞凋亡。     

DNA引物酶抑制剂碘化-3,3′-二乙基-9-甲基-硫杂羰花青诱导人白血病HL-60细胞凋亡

目的研究DNA引物酶抑制剂碘化-3,3′-二乙基-9-甲基-硫杂羰花青(DMTCCI)诱导人粒细胞性白血病HL-60细胞凋亡并探索其机制。方法分别采用不同浓度的DMTCCI处理培养于RPMI-1640培养基的HL-60细胞。采用MTT法检测DMTCCI对HL-60细胞的生长抑制作用。采用流式细胞仪和DNA琼脂糖凝胶电泳方法检测细胞凋亡。采用蛋白免疫印迹(Western blotting)法观察凋亡相关蛋白survivin， Bcl-xL， Bad， Bax， Bcl-2， caspase-9， caspase-3， caspase-6， PARP， DFF45和lamin B的表达。采用ApoAlert Caspase-3分析试剂盒检测caspase-3的活性。结果DMTCCI具有抑制人白血病HL-60细胞增殖的作用，其IC₅₀值为0.24 μmol·L^-1。流式细胞仪和DNA琼脂糖凝胶电泳结果显示，DMTCCI可诱导HL-60细胞凋亡。在经DMTCCI处理的HL-60细胞中，survivin和Bcl-xL蛋白的表达水平下调，Bad和Bax蛋白的表达水平上调，Bcl-2蛋白的表达水平无变化，caspase-9，caspase-3，caspase-6，PARP，DFF45和lamin B被分别裂解，产生相应裂解产物。在HL-60细胞中，caspase-3的活性在1 μmol·L^-1 DMTCCI处理3 h时明显升高，在处理12 h时达到最高峰。结论DMTCCI可抑制人白血病HL-60细胞的增殖并诱导其发生细胞凋亡。Bcl-2家族蛋白、survivin和caspases家族蛋白可能参与了上述诱导HL-60细胞凋亡的过程。     

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.     

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.     

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.