Bacterial degradation of microcystin toxins in drinking water eliminates their toxicity.

Microcystin-LR and -LA were readily biodegraded by a bacterium, Sphingpoyxis sp. LH21, in a treated reservoir water. Detection of the microcystins was conducted using high-performance liquid chromatography (HPLC), protein phosphatase 2A (PP2A) inhibition assay and a cell-based cytotoxicity assay. The HPLC results correlated well with the two assays. The decrease in cytotoxicity, coupled with the associated decrease in microcystin concentrations, indicated that no cytotoxic by-products were being generated, highlighting the applicability of biodegradation as a feasible treatment option for effective microcystin removal.     

应用MTT法进行体外抗肿瘤药敏试验影响因素研究

目的:探讨应用MTT法进行体外抗肿瘤药敏试验的影响因素,旨在建屯一种MTT法抗肿瘤药敏试验的规范化流程.方法:MTT法测定不同浓度人外周血单个核细胞(PBMC)对不同浓度的奥沙利铂与紫杉醇的敏感性,同时优化选择培养时间与MTT孵育时间.结果:在每孔PBMC为4.0×104(浓度为4.0×105/mL)、药物作用时间48h、MTT 20 μL作用6 h、单波长570 nm处测OD值时,药物对细胞的抑制率较高,试验效果较好.结论:规范化的MTT法体外抗肿瘤药敏试验为临床医生开展和实现个性化化疗提供了可靠的依据.     

中药及其有效成分调节小鼠成纤维细胞瘤细胞活性的研究

目的动态观察6种中药或有效成分对小鼠成纤维细胞瘤细胞(L-929细胞)活性的影响,筛选出对其有效的药物。方法以传代培养的L-929细胞为靶细胞,以MTT比色法测定细胞活性。每种药选择3个浓度,连续观测5个时间点。结果经统计学分析,复方丹参注射液等6个药物与对照组相比对L-929细胞有一定的抑制作用,而且某些药的不同浓度之间的抑制作用也有显著差异。肿瘤坏死因子与其他药物作用比较抑制作用最为明显。结论本实验系统正确、可靠,复方丹参注射液等6种药物有不同程度的抑制L-929细胞活性的作用。     

MTT法在检测细胞因子与细胞毒效应中的应用

抗癌效应细胞(NK、LAK、CTL、Mφ)细胞毒效应、细胞因子和肿瘤化疗药敏检测目前多采用同位素法,但存在着使用同位素而引起的弊端。寻找一种简便,敏感及安全的检测手段已成为当务之急。我们将MTT比色法用于抗癌效应细胞功能、细胞因子及化疗药敏测定,并与同位素方法进行了对比,结果表明两种方法具有良好的相关性,MTT法与后者相比更为简便、经济、安全和实用。     

Antitumor activity of cis-diamminedichloroplatinum (II) depends on its time × concentration product against human gastric cancer cell lines in vitro

A pharmacodynamic study of cisplatin (DDP) was conducted using the gastric cancer cell lines MKN-45 and MKN-74 in vitro. Ten thousand tumor cells were incubated with 0.4–500 μg/ml DDP for 1–25 h, followed by recovery culture for a further 48 h. At the end of incubation, cell viability was detected by the MTT end-point, and the inhibition rate was compared in relation to the incubation time, DDP concentration, and the time × concentration product (area under the curve in vitro: AUC vitro). In both of the cell lines, the IC50 and IC90 values decreased as the exposure time increased, going a linear curve with a slope of almost — 1, and showing a typical log-log AUC vitro-dependent curve. These results indicate that the antitumor activity of DDP is dependent on its AUC vitro, suggesting the clinical usefulness of this drug when administered daily in small divided doses. © 1995 Wiley-Liss, Inc.     

Indomethacin-induced mitochondrial dysfunction and oxidative stress in villus enterocytes

Nonsteroidal anti-inflammatory drugs (NSAIDs) are known to cause small intestinal damage but the pathogenesis of this toxicity is not well established. Intestinal epithelial cells are thought to be affected by these drugs in the course of their absorption. These cells are of different types, viz. villus, middle and crypt cells. There is little information on which of these cells, if any, are particularly vulnerable to the effects of NSAIDs. This paper aimed to study the effects of indomethacin, an NSAID commonly used in toxicity studies, on different populations of enterocytes. Effects of the drug were assessed in terms of oxidative damage, mitotic activity, mitochondrial function and lipid composition in enterocytes isolated from the small intestine of rats that had been orally administered indomethacin. In addition, the effects of arginine and zinc in protecting against such changes were assessed. Cell viability, tetrazolium dye (MTT) reduction and oxygen uptake were significantly reduced in villus tip cells from rats dosed with the drug. Thymidine uptake was higher in the crypt cell fraction from these rats. Similarly, products of lipid peroxidation were elevated in the villus tip cells with a corresponding decrease in the level of the anti-oxidant, alpha-tocopherol. In isolated mitochondrial preparations from various enterocyte fractions, significant functional impairment and altered lipid composition were seen mainly in mitochondria from villus cells. Arginine and zinc pre-treatment were found to protect against these effects. These results suggest for the first time that the villus tip cells are more vulnerable to the damaging effects of indomethacin and that oxidative stress is possibly involved in this damage.     

瑞香狼毒提取物对小鼠H22肝癌细胞细胞周期的影响

目的 研究中药瑞香狼毒三种不同提取物A、B、C(SCL-A、SCL-B、SCL-C)在体外对小鼠H22肝癌细胞的抑制作用,并探讨其抑制肿瘤的作用机制.方法 联合应用细胞培养技术,MTT比色法,流式细胞术等方法研究三种不同的提取物在体外对小鼠H22肝癌细胞的抑制作用.结果 体外MTT实验结果显示,三种提取物作用于体外培养的H22肝癌肿瘤细胞后,细胞的增殖明显受到抑制,用药组细胞培养孔的OD值明显小于对照组,表现出正的剂量效应关系.SCL-A、SCL-B和SCL-C的IC50分别是:0.43 μg/mL、0.26 μg/mL、0.15 μg/mL.流式细胞分析表明,经药物作用后细胞被阻止在G0G1期,PI指数明显降低,AI指数明显增高.结论 体外抗肿瘤研究表明,SCL-A、SCL-B和SCL-C作用于H22细胞后,可明显抑制细胞增殖、阻止细胞在G0G1期.瑞香狼毒的三种提取物均具有显著抗肿瘤作用.     

用甲基噻唑蓝筛选抗铜绿假单胞菌药物方法的建立

目的:建立适合铜绿假单胞菌的定量、快速、体外高通量药物筛选方法。方法:优化甲基噻唑蓝法检测活细菌数量的实验条件,用MIC方法与MTT法比较2种已知抗生素的抗菌作用。结果:微量培养对细菌生长无影响,最佳MTT浓度和反应时间分别为5 mg·mL-1和1 h。在同一培养时间,菌浓度在1×107～1×1010CFU·mL-1范围内,甲臜的吸收度与菌浓度呈线性相关。用2种抗生素比较MIC方法与MTT法药敏测定的结果一致。结论:MTT微量法进行抗铜绿假单胞菌新药筛选操作简便,省时省力,成本较低,结果稳定,具有可重复性,适宜体外高通量药物筛选。     

维甲酸对宫颈癌细胞耐药株增殖及药物敏感性的影响

目的:探讨全反式维甲酸(ATRA)对宫颈癌耐药株HeLa/MMC的增殖及药物敏感性的影响及其作用的分子机制。方法:观察ATRA作用下HeLa/MMC细胞的增殖,MTT法观察ATRA对HeLa/MMC药物敏感性的影响,半定量RT-PCR检测mdr1基因的表达情况。结果:①ATRA对HeLa/MMC细胞的增殖有抑制作用,这一作用为非细胞毒抑制作用。②ATRA能提高MMC对HeLa/MMC细胞的杀伤作用,并呈剂量依赖性。③半定量RT-PCR结果显示,ATRA上调了HeLa/MMC细胞mdr1基因的表达。结论:表明ATRA能抑制HeLa/MMC的增殖,提高HeLa/MMC对MMC的敏感性,但这种作用与mdr1基因表达无关。