正常昆明种与NIH种小鼠自然发生微核率的比较

目的： 比较正常昆明种与NIH种小鼠胸骨骨髓嗜多染红细胞微核的自然发生率。 方法： 按《食品安全性毒理学评价程序和方法》采用30 h法微核试验,计数微核数,计算微核率。 结果： 小鼠胸骨骨髓PCE自然发生率呈正偏态分布,中位数能较好的代表其平均水平,昆明种小鼠胸骨骨髓PCE微核自然发生率(‰),雌鼠为1.0(0, 4.0),雄鼠为2.0(0, 6.0),性别间差异有统计学意义(P<0.05);NIH种小鼠胸骨骨髓PCE微核数自然发生率(‰),雌鼠为2.0(0, 3.0),雄鼠为2.0(0, 6.0),性别间差异无统计学意义。昆明种和NIH种小鼠胸骨骨髓PCE自发微核率间差异无统计学意义。 结论： 昆明种与NIH种小鼠胸骨骨髓PCE微核的自然发生率与其他人的研究较接近,昆明种与NIH种小鼠品系间差异无统计学意义,而昆明种小鼠性别间差异有统计学意义。     

河南蜂胶的抗突变作用研究

目的探讨河南蜂胶对环磷酰胺(CP)诱发基因突变的抑制作用。方法应用小鼠骨髓微核实验检测河南蜂胶对环磷酰胺诱发突变的抑制作用。结果蜂胶对诱变剂所诱发的突变产生了抑制作用,其中500mg·kg-1、2000mg·kg-1剂量蜂胶组对CP诱变具有中等抑制,8000mg·kg-1剂量组对CP诱变具有强度抑制。蜂胶本身无诱变活性。结论蜂胶对CP诱发的基因突变有一定的抑制作用。     

旋转强磁场对大鼠生殖毒性的探索

背景与目的： 研究旋转强磁场对大鼠生殖及对其后代细胞遗传毒性,从而验证强度为0.4 T的旋转强磁场对生物体的安全性。 材料与方法： 大鼠采用曝磁0.5、1、2 h/d 3个剂量组、一个阴性对照组和一个阳性对照组,对各组大鼠进行精子畸形实验、传统致畸实验和微核及核型实验,分别观察大鼠精子形态、后代的生长发育情况、微核千分率及对比染色体G带显色带型的变化。 结果： 0.4 T 旋转强磁场对大鼠精子无影响;对孕鼠的体重和妊娠未见影响,亦无其它发育毒性;对大鼠骨髓无抑制作用,微核实验为阴性结果;染色体G带显色带型无差别。 结论： 在0.4 T旋转强磁场中,曝磁2 h/d对大鼠无生殖毒性,对其后代无遗传毒性。     

Significance of formaldehyde-induced DNA–protein crosslinks for mutagenesis

Formaldehyde (FA) is a genotoxic substance, induces tumors in the nasal epithelium of rats, and is suspected to be a human carcinogen. As a primary DNA lesion, FA induces DNA–protein crosslinks (DPC) and the formation of DPC has been used as a measure of exposure for risk estimation. However, the significance of DPC for mutagenesis and carcinogenesis is at present poorly understood. We therefore performed comparative investigations on the induction of DPC and other genetic endpoints by FA in V79 Chinese hamster cells. The amount of DPC was comparatively determined with the K-SDS assay and the comet assay. Both tests gave similar results but the comet assay was much faster and easier to perform. Our results show that FA significantly induces DPC, sister-chromatid exchanges, and micronuclei in the same range of concentrations, parallel to the induction of cytotoxicity (relative cloning efficiency). In contrast, treatment of V79 cells with FA did not induce gene mutations in the HPRT test even after variations of the treatment protocol. Our results indicate that FA-induced DPC seem to be related to cytotoxicity and clastogenicity but do not lead to the formation of gene mutations in mammalian cells. It is suggested that FA-induced DPC do not cause gene mutations that are involved in FA-induced carcinogenesis. Environ. Mol. Mutagen. 32:260–268, 1998 © 1998 Wiley-Liss, Inc.     

1,4-Dioxane is not mutagenic in five in vitro assays and mouse peripheral blood micronucleus assay,but is in mouse liver micronucleus assay

1,4-Dioxane, an animal carcinogen, was not previously genotoxic in in vitro assays. We reevaluated the compound's genotoxic potential in five in vitro genotoxicity tests in the presence and absence of S9 mix using recommended new protocols. We used the bacterial reverse mutation assay with Salmonella TA and E. coli WP2 strains, including the plate and preincubation methods, the CHO chromosomal aberration assay, including examination of polyploid induction and extended sampling time, the CHO sister-chromatid exchange assay with short and long treatment time, the mouse lymphoma tk assay (microtiter method), including longer treatment time (24 hr), and the CHO micronucleus assay with short and long treatment times. The highest concentration we used was five mg/ml or plate. We also evaluated the genotoxic effect of 1,4-dioxane in vivo by conducting peripheral blood and liver micronucleus assays in the same mice after single oral administration of up to 3,000 mg/kg. All in vitro assays and the peripheral blood micronucleus assay were negative. The mouse liver micronucleus assay, on the other hand, was positive, indicating that 1,4-dioxane might be genotoxic. It is also conceivable that the positive result in mouse liver micronucleus assay was due to a nongenotoxic mechanism, i.e., errors in genetic repair following enhancement of hepatocyte proliferation. Environ. Mol. Mutagen. 32:269–280, 1998 © 1998 Wiley-Liss, Inc.     

Evaluation of a new procedure for the flow cytometric analysis of in vitro,chemically induced micronuclei in V79 cells

Measurement of the frequency of micronuclei induced in cells by ionizing radiation or by chemical treatment is widely used to analyze cytogenetic damage. The microscopic scoring of micronuclei is a tedious and time-consuming procedure. Therefore, attempts have been made to automate micronuclei scoring by means of image analysis or flow cytometry. A new procedure for the flow cytometric analysis of chemically induced micronuclei in V79 Chinese hamster cells has been established in our laboratory. Debris was separated from micronuclei by means of a new gating procedure using area and width fluorescence of the stained suspension of micronuclei and nuclei. In order to test the sensitivity and specificity of this improved method of flow cytometric analysis, five well-known mutagenic compounds were tested. With the new technique, the frequency of micronuclei measured and analyzed corresponded well with results obtained by conventional microscopy. In addition, a large series of negative compounds, and weak, middle, and strong micronuclei inducers, were tested in order to establish criteria for discrimination between genotoxic and nongenotoxic compounds by flow cytometry. This new procedure for flow cytometric detection of micronuclei represents a quick, reliable, and relatively simple method for in vitro micronucleus testing. Environ. Mol. Mutagen. 32: 387–396, 1998 © 1998 Wiley-Liss, Inc.     

Cytogenetic biomonitoring in traffic police workers: Micronucleus test in peripheral blood lymphocytes

Atmospheric pollution represents a relevant environmental hazard which has been associated with considerable excess mortality, morbidity, and increased rates of respiratory diseases in humans. To date, more than 3,000 environmental chemical compounds have been identified in the ambient atmosphere, including a variety of mutagenic and/or carcinogenic agents, such as polycyclic aromatic hydrocarbons (PAHs), aromatic amines, and heterocyclic compounds. Positive associations between cytogenetic markers and airborne levels of PAHs have been reported by experimental and human studies. Traffic has been implicated as the major determinant for the concentration of PAHs and, therefore, for the genotoxic activity of urban air. A biomonitoring study has been conducted in 82 Italian traffic police workers exposed to air pollutants and 34 control subjects (matched by age, gender, and smoking habits) not exposed to traffic pollutants. The aim of this study was to assess the cytogenetic effects, such as micronucleus frequency in peripheral blood lymphocytes, and to estimate the association with individual exposure to PAH. Statistical analysis of the frequency of micronuclei in binucleated cells showed higher mean levels in referent subjects (4.03%) than in traffic police officers (3.73%). Smoking showed no effect on the frequency of micronuclei. The study failed to detect any association between micronucleus frequency and individual level of benzo(a)pyrene, considered a marker of exposure to PAHs. These findings indicate that exposure to urban air pollutants does not result in increased levels of micronuclei in peripheral white blood cells. Environ. Mol. Mutagen. 30:396–402, 1997 © 1997 Wiley-Liss, Inc.     

Genotoxic and antigenotoxic effects of Hemidesmus indicus R. Br. root extract in cultured lymphocytes

Aim of the study

The genotoxic and antigenotoxic potential of the ethanolic extract of Hemidesmus indicus roots were evaluated in cultured human lymphocytes using cisplatin as the positive mutagen.

Materials and methods

Cytogenetic damage and cytotoxicity were determined in cells exposed to different doses of the extract, ranging from 2 to 32 μg/ml of culture medium, either alone or together with cisplatin.

Results

There was a significant reduction in cisplatin-induced frequencies of sister chromatid exchanges, chromosome aberrations and micronucleated binucleate cells at the lower concentrations of 4 and 8 μg/ml (P < 0.05). However, the extract by itself reduced the proliferative rate index, mitotic index and cytokinesis-block proliferative index (P < 0.05). Further, a significant increase in the percentage of chromosome aberrations was noticed at the higher concentrations.

Conclusion

Hemidesmus indicus root extract possesses significant genoprotective effect at the lower concentrations although it is cytotoxic and probably genotoxic at higher doses.     

正交设计法研究环磷酰胺诱导小鼠骨髓细胞微核的影响因素

目的　研究环磷酰胺诱导小鼠骨髓细胞微核的影响因素 ,确定其在实验中作为阳性对照剂使用的优化因素水平组合。方法　采用正交设计 ,考察剂量、取样时间、小鼠体重、性别对MN率、PCE/ (PCE +NCE)结果的影响。结果　对MN率 ,上述因素的影响均有统计学意义 (P <0 .0 1 ) ,产生最高MN率的因素水平组合为 :剂量 1 60mg·kg- 1 、取样时间 30h、小鼠体重 1 7～ 1 9g、性别♂。对PCE/ (PCE +NCE) ,仅剂量因素有显著影响 (P <0 .0 1 ) ,当剂量为 1 60mg .kg- 1 时 ,该指标K1 最低 ,为 2 2 .5 % ;其它因素则未显示出明显的影响。结论　根据实验要求 ,经综合考虑二项观察指标结果 ,确定环磷酰胺微核试验的优化因素水平组合条件为 :剂量 80mg·kg- 1 、取样时间ip后 30h、小鼠体重 1 7～ 1 9g、性别♂。     

银参胶囊遗传毒性研究

目的探讨银参胶囊的遗传毒性。方法选用SPF级健康ICR小鼠,通过Ames试验、小鼠骨髓细胞微核试验、小鼠睾丸染色体畸变试验等遗传毒性试验验证银参胶囊的安全性。结果 Ames试验中,银参胶囊在8~5 000μg/皿剂量范围内,无论是否加入哺乳动物肝脏微粒体酶(S9),鼠伤寒沙门菌TA97,TA98,TA100,TA102等4株菌的回复突变菌落数均未出现剂量依赖性增加;微核试验中,2 500,5 000,10 000 mg/kg剂量组均未见骨髓中含微核的嗜多染红细胞数增加;小鼠睾丸染色体畸变试验中,药物质量分数为2 500,5 000,10 000 mg/kg时,细胞的染色体畸变率均未出现剂量依赖性增加。结论银参胶囊未显示致突变作用,可初步判定其在遗传毒性方面是安全的。