GLP体制下细菌回复突变试验的实施

细菌回复突变试验(Bacterial Reverse Mutation Test,Ames Test)作为化学品及药物遗传毒初筛的经典方法,已在致突变研究中应用了30多年,但在试验操作程序和规范方面仍存在一些问题。文中将在GLP(Good Laboratory Practice)体制下实施细菌回复突变试验的做法进行总结,以确保获取完整、真实、可靠的研究数据。     

猫眼草水煎液体外致突变性的研究

目的检验猫眼草水煎液的致突变性;改进经典的A-mes试验体系使之适应于中药体外致突变性检验。方法通过经典的Ames试验检测猫眼草的体外致突变性;通过哺乳动物骨髓细胞染色体畸变试验检测猫眼草的致畸作用;改进的Ames试验通过增设含补充组氨酸(含量对应于猫眼草水煎液中组氨酸浓度)的阴性对照,排除样品中组氨酸成分对试验结果的影响。结果猫眼草水煎液在经典的Ames试验中为强阳性;对哺乳动物骨髓细胞染色体致畸作用为阴性;在改进的Ames试验中猫眼草水煎液的致突变性为阴性。结论经典的Ames试验不适合猫眼草水煎液致突变性检测,改进后的Ames实验体系适合。猫眼草水煎液在体外和体内均没有致突变性。     

1485种化学物致突变试验和致癌试验结果一致性比较

目的探讨Ames试验与致癌试验结果的一致性。方法利用致癌强度数据库(CPDB),对其截至2007年6月收录的1485种化学物的致突变和致癌试验结果进行统计分析。结果Ames试验检测的化合物有899种,大鼠致癌试验检测的化合物有1170种。同时进行Ames试验和大鼠肿瘤试验的化合物有721种,其中Ames试验阳性的化合物有343种,引起大鼠肿瘤的化合物有345种,Ames试验阳性同时引起大鼠肿瘤的化合物有238种。大鼠试验检测出的致癌物中Ames试验检出率为69.0%,Ames试验检出的致突变物中大鼠致癌试验的检出率为69.4%。恒河猴致癌试验检测的化合物有24种,同时进行Ames试验和恒河猴致癌试验的化合物有21种,其中Ames试验阳性的化合物有18种,引起恒河猴肿瘤的化合物有8种,Ames试验阳性同时能引起恒河猴肿瘤的化合物有7种。恒河猴试验检测出的致癌物中Ames试验检出率为87.5%,Ames试验检出的致突变物中恒河猴致癌试验的检出率为38.9%。结论Ames致突变试验和大鼠致癌试验有较好的一致性,Ames试验检出的致突变物在恒河猴致癌试验中阴性结果较高。     

现行药物、保健食品和化妆品Ames试验方法的比较分析

Ames试验广泛应用于药物、食品、化妆品及医疗器械的遗传毒性研究,是应用最广泛的检测基因突变的体外试验.药物、保健食品和化妆品Ames试验方法有一定的差异,该文就药物、保健食品和化妆品Ames试验方法的主要异同点作一比较分析.     

复方苯酚糊剂的致突变研究--Ames试验

Dobias等报道抗寄生虫药物甲硝哒唑(灭滴灵,Metronidazale)的致突变性可用人或实验动物血液中代谢物出现的突变性评价。在复方苯酚糊剂的组分中,阿的平对Ames法所用的试验菌TA 1537显示致突变性,有时它还被用作TA 1537的阳性对照[浙江医科大学农药研究室:Ames试验评价,内部资料]。故我们采用动物给药后测其血液的突变性以探讨绝育药物复方苯酚糊剂对人产生致突变的可能性。     

藿莲香Ⅱ号复方的致突变性研究

目的根据《食品安全性毒理学评价程序和方法》(GB15193-2003)对中药复方藿莲香Ⅱ号进行相关的毒理学评价。方法应用急性毒性试验、小鼠骨髓嗜多染红细胞微核试验、小鼠骨髓细胞染色体畸变试验和Ames试验检测该复方的急性毒性和致突变性。结果急性经口毒性试验:雌性、雄性小鼠经口最大无毒浓度(MTD)为10g/kg体质量,属实际无毒;致突变实验:小鼠骨髓嗜多染红细胞微核试验、小鼠骨髓细胞染色体畸变试验和Ames试验结果均为阴性,显示在本实验条件下,该配伍未见有致突变性作用。结论藿莲香Ⅱ号未见有致突变性作用。     

中药复方藿莲香Ⅰ号的遗传毒理学研究

目的：根据前期藿莲香Ⅰ号药效学研究结果,进一步研究该复方的急性毒性和致突变作用,为其进一步应用的安全性提供理论依据。方法应用急性毒性实验、小鼠骨髓嗜多染红细胞微核试验、小鼠骨髓细胞染色体畸变试验和Ames试验检测该组分配伍复方的急性毒性和致突变性。结果急性经口毒性试验：雌性、雄性小鼠经口MTD均大于10g＆#183;kg-1,属实际无毒。致突变实验：小鼠骨髓嗜多染红细胞微核试验、小鼠骨髓细胞染色体畸变试验和Ames试验结果均为阴性,显示在本实验条件下,该中药复方未见有致突变性作用。结论中药复方藿莲香Ⅰ号未见有明显的急性毒性和致突变作用,表明该药物安全性良好。     

噻嗪酮的致突变性检测

噻唪酮是防治稻虱等病虫害的新型农药,具有用量少、效果好和毒性低的特点。参照我国农药注册的规定方法,我们对其致突变性进行了检测。 噻嗪酮:上海某厂合成,纯度>98％,为白色结晶。Ames试验用DMSO溶解,微核和显性致死     

长春西汀的致突变研究

目的 :检测长春西汀是否有致突变作用。方法 :采用Ames试验 ,小鼠微核试验及哺乳动物培养细胞染色体畸变试验观察长春西汀的诱变性。结果 :Ames试验 ,微核试验及染色体畸变试验结果均为阴性。结论 :长春西汀在所试条件下未见致突变作用。     

一种灵敏的细菌正向突变试验方法

目前已建立的遗传毒性检测技术有 2 0 0多种 ,其中 ,Ames试验最为常用。Ames试验 ,也就是鼠伤寒沙门菌组氨酸营养缺陷型的回复突变试验 ,是Ames等在70年代建立起来的。 1983年 ,Maron和Ames把该方法规范化 ,选用鼠伤寒沙门菌的 4种品系 (TA97,TA98,T10 0 ,TA10 2 )为标准菌株来检测外源化学物的致突变能力[1 ] 。这种方法被许多实验室采纳 ,广泛用于检测食品、化妆品、药品和饮用水等测试样中的致变物。但是 ,有 2个客观事实限制了它的应用 :(1)某些DNA分子诱变物不能使所用的细菌品系发生回变 ,因此 ,回复突变试验就不能用于这类物质…     

34种待选药物诱变性预测及分子结构基础分析

CASE (computer automated structure evaluation)系统是一种根据化学物质结构预测其诱变性或致癌性的计算机辅助系统,本文介绍了一种可在IBM 286微机上运行的CASE系统,通过对数千种已知生物活性的化学物质结构的综合分析,建立了与活性有关的局部结构(片段)数据库和知识库,并对34种待选药物Ames试验作了预测,与文献报道基本一致(96.4％);同时也对其分子基础作了分析,由于CASE的预测程序是由计算机完成的,速度极快,因此是设计和筛选低毒药物有效的辅助方法,并可为进一步选择生物学检测方法提供参考。     

Mutagenicity evaluation of pesticide analogs using standard and 6-well miniaturized bacterial reverse mutation tests

The Ames test is widely used in the mutagenicity evaluation of new and existing chemicals as a part of a compound selection strategy, regulatory control, the equivalence assessment, carcinogenic potential measurement etc. Intensification of the chemical industry and synthesis of plenty of new molecules has led to the necessity of tests with a higher throughput capacity. The 6-well miniaturized bacterial reverse mutation test and the standard Ames test were compared using 14 technical grade active ingredients (TGAIs) of pesticides. With some exceptions, the responses obtained in the miniscreen Ames are similar to those seen in the standard method: 4 overall test outcomes were negative and 9 were positive in both test versions, but 1 discordant result between the miniscreen and standard version. Comparison of the standard and the miniscreen Ames test resulted in 98% of concordance across five strains and conditions (±S9). The overall judgment is that the miniscreen Ames test can be used to assess the mutagenicity of pesticide analogs. It has the advantage of decreasing the number of materials and animals (for S9) and keeping a high-test performance.     

Identifying the structural requirements for chromosomal aberration by incorporating molecular flexibility and metabolic activation of chemicals

Modeling the potential of chemicals to induce chromosomal damage has been hampered by the diversity of mechanisms which condition this biological effect. The direct binding of a chemical to DNA is one of the underlying mechanisms that is also responsible for bacterial mutagenicity. Disturbance of DNA synthesis due to inhibition of topoisomerases and interaction of chemicals with nuclear proteins associated with DNA (e.g., histone proteins) were identified as additional mechanisms leading to chromosomal aberrations (CA). A comparative analysis of in vitro genotoxic data for a large number of chemicals revealed that more than 80% of chemicals that elicit bacterial mutagenicity (as indicated by the Ames test) also induce CA; alternatively, only 60% of chemicals that induce CA have been found to be active in the Ames test. In agreement with this relationship, a battery of models is developed for modeling CA. It combines the Ames model for bacterial mutagenicity, which has already been derived and integrated into the Optimized Approach Based on Structural Indices Set (OASIS) tissue metabolic simulator (TIMES) platform, and a newly derived model accounting for additional mechanisms leading to CA. Both models are based on the classical concept of reactive alerts. Some of the specified alerts interact directly with DNA or nuclear proteins, whereas others are applied in a combination of two- or three-dimensional quantitative structure-activity relationship models assessing the degree of activation of the alerts from the rest of the molecules. The use of each of the alerts has been justified by a mechanistic interpretation of the interaction. In combination with a rat liver S9 metabolism simulator, the model explained the CA induced by metabolically activated chemicals that do not elicit activity in the parent form. The model can be applied in two ways: with and without metabolic activation of chemicals.     

Validation of the (Q)SAR combination approach for mutagenicity prediction of flavor chemicals

Most exposure levels of flavor in food are considered to be extremely low. If at all, genotoxic properties should be taken into account in safety evaluations. We have recently established a (quantitative) structure–activity relationship, (Q)SAR, combination system, which is composed of three individual models of mutagenicity prediction for industrial chemicals. A decision on mutagenicity is defined as the combination of predictive results from the three models. To validate the utility of our (Q)SAR system for flavor evaluation, we assessed 367 flavor chemicals that had been evaluated mainly by JECFA and for which Ames test results were available. When two or more models gave a positive evaluation, the sensitivity was low (19.4%). In contrast, when one or more models gave a positive evaluation, the sensitivity increased to 47.2%. The contribution of this increased sensitivity was mainly due to the result of the prediction by Derek for Windows, which is a knowledge-based model. Structural analysis of false negatives indicated some common sub-structures. The approach of improving sub-structural alerts could effectively contribute to increasing the predictability of the mutagenicity of flavors, because many flavors possess categorically similar functional sub-structures or are composed of a series of derivatives.     

Genotoxicity studies OF p-dimethylaminoazobenzene (DAB)

The potential genotoxicity of the rodent liver carcinogen p-dimethylaminoazobenzene (DAB) was evaluated in compliance with the guidelines for genotoxicity studies of drugs (Notification No. 1604, Nov. 1, 1999, Ministry of Health and Welfare, Japan) and the OECD guidelines for testing chemicals. DAB was clearly positive in both the bacterial reverse mutation test (Ames test) and in vitro chromosomal aberration test in the presence of metabolic activation, whereas it was weakly positive at toxic doses in the rat bone marrow micronucleus test. It has been reported that DAB was clearly positive in in vivo genotoxicity tests, i.e., a mouse alkaline single cell gel electrophoresis (comet) assay and a young rat liver micronucleus test. These results suggest that the test system using the liver is effective for in vivo genotoxicity assessment of chemicals that show mutagenicity in in vitro genotoxicity tests in the presence of metabolic activation.     

Limitations of urinary mutagen assays for monitoring occupational exposure to antineoplastic drugs

The sensitivity of the Salmonella reversion test of Ames as a screen for accidental absorption of 17 antineoplastic agents by drug handlers was evaluated. Dilutions of each drug were added to agar inoculated with each of two Salmonella typhimurium strains (TA98 and TA100); control plates contained no test drug. Colonies were counted after incubation at 36 degrees C for 48 hours. The drugs were tested in the presence of a liver preparation to provide metabolic activation of mutagenicity. Urine samples collected from patients after doses of three mutagenic drugs were extracted and tested with the Ames test. For 11 of the 17 drug solutions, no mutagenic activity was seen, but many of these 11 were toxic to the organisms. The most highly mutagenic drugs were doxorubicin and cisplatin, with mechlorethamine, carmustine, dacarbazine, and cyclophosphamide exhibiting less mutagenic activity. Urine from patients treated with doxorubicin or cyclophosphamide showed mutagenicity, but the results suggested that the quantity of these drugs that would have to be absorbed to produce a definite reaction in urine is unlikely to be achieved by drug handlers who use standard precautions. Because of its lack of sensitivity and the potential effects of environmental and dietary factors on the results, this bacterial mutagenicity test should not be used routinely for detection of accidental absorption of antineoplastic drugs.     

Primary mutagenicity screening of food additives currently used in Japan

Salmonella/microsome tests (Ames tests) and chromosomal aberration tests in vitro using a Chinese hamster fibroblast cell line were carried out on 190 synthetic food additives and 52 food additives derived from natural sources, all of which are currently used in Japan. Fourteen out of 200 tested in the Ames assay showed positive effects and 54 out of 242 were positive in the chromosome test. Three additives (erythorbic acid, chlorine dioxide and beet red) were positive only in the Ames test, although their mutagenic potentials were relatively weak, while 43 additives were positive only in the chromosome test. Eleven additives (calcium hypochlorite, cinnamic aldehyde, L-cysteine monohydrochloride, Food Green No. 3 (Fast Green FCF), hydrogen peroxide, potassium bromate, sodium chlorite, sodium hypochlorite, sodium nitrite, cacao pigment and caramel) were positive in both the Ames test and the chromosome test. The usefulness of such primary screening tests combining two different genetic end-points, gene mutation and chromosomal aberration, and some correlation between mutagenicity and carcinogenicity of food additives are discussed.     

In-vitro mutagenic potential and effect on permeability of co-administered drugs across Caco-2 cell monolayers of Rubus idaeus and its fortified fractions

This study investigated the mutagenic, anti-mutagenic and cytotoxic effects of acetone extract of raspberry, Rubus idaeus L. (v. Ottawa) Rosaceae, and the isolated and characterized ellagitannin and anthocyanin fractions thereof, suitable for food applications. The studied raspberry extract and fractions did not show any mutagenic effects determined in the miniaturized Ames test and were not cytotoxic to Caco-2 cells at the used concentrations. However, the anti-mutagenic properties were changed (i.e. decreased mutagenicity of 2-nitrofluorene in strain TA98, and slightly increased mutagenicity of 2-aminoanthracene in strain TA100) with metabolic activation. Further, their influence on the permeability of co-administered common drugs (ketoprofen, paracetamol, metoprolol and verapamil) across Caco-2 monolayers was evaluated. The apical-to-basolateral permeability of highly permeable verapamil was mostly affected (decreased) during co-administration of the raspberry extract or the ellagitannin fraction. Ketoprofen permeability was decreased by the ellagitannin fraction. Consumption of food rich in phytochemicals, as demonstrated here with chemically characterized raspberry extract and fractions, with well-absorbing drugs would seem to affect the permeability of some of these drugs depending on the components. Thus their effects on the absorption of drugs in-vivo cannot be excluded.