Chromosomal aberrations and frequency of micronuclei in sheep subchronically exposed to the fungicide Euparen Multi (tolylfluanid)

We analyzed chromosome aberrations, micronucleus frequency, mitotic index (MI), and nuclear division index (NDI) in peripheral lymphocytes of sheep subchronically exposed to the fungicide Euparen Multi (containing 50% tolylfluanid). Euparen Multi was administered by rumen sonde to group of Merino sheep (seven sheep/group) at 93 mg/kg body weight (1/20 LD50) daily for 28 days to assess its genotoxic effects. The frequencies of aberrant cells (ABC) in the experimental and control groups were 5.50+/-1.38% and 2.40+/-1.14%, respectively, and the increase in ABC in the treated group was significant (P = 0.003). Significantly increased numbers of chromatid breaks (5.67+/-1.21% against 2.40+/-1.14%; P = 0.001), chromatid gaps (10.33+/-2.73% against 4.00+/-1.23%; P = 0.001), and chromosome gaps (1.83+/-0.75% against 0.80+/-0.45%; P = 0.025) and exchanges (3.17+/-1.94% against 0.20+/-0.45%; P = 0.009) were observed in exposed animals in comparison to control animals. The frequency of micronuclei (MN) was 29.40+/-5.86 per 1000 binucleated cells in peripheral lymphocytes of sheep in the control group and 49.57+/-19.12 per 1000 binucleated cells in the treated group. A significant increase in the frequency of MN in peripheral lymphocytes also was observed between the two groups (P = 0.0477). No statistical differences in MI and NDI values were found in the groups (P = 0.181 and 0.761, respectively). Thus, our results suggest that exposure to Euparen Multi may cause genome damage in somatic cells.     

Effect of a low-dose ethinylestradiol and gestodene in combination on the frequency of micronuclei in human peripheral blood lymphocytes of healthy women in vivo

BACKGROUND: Since most oral hormonal contraceptives contain a fixed combination of ethinylestradiol and gestodene as an estrogenic/progestogenic component, we decided to evaluate the possible mutagenic effect of a low-dose contraceptive pills containing 20 microg ethinylestradiol and 75 microg gestodene. METHODS: A total of 30 healthy women received hormonal contraception during six consecutive menstrual cycles. A single daily dose was 20 microg ethinylestradiol and 75 microg gestodene. The pills were taken orally in a monthly cycle of 3 weeks on and 1 week off. In the investigation of the mutagenic effect of these contraceptive pills in vivo, the cytokinesis block micronucleus (CBMN) test was used, and the frequency of micronuclei (MN) in peripheral blood lymphocytes was determined. RESULTS: Average MN frequency in women before therapy was 7.40 +/- 0.75 MN/1000 analyzed cells, and after therapy was 7.37 +/- 0.59 MN/1000 analyzed cells (p > 0.05). CONCLUSION: Our data suggest that oral contraception with 20 microg ethinylestradiol and 75 microg gestodene in combination during six consecutive menstrual cycles does not induce micronuclei in peripheral blood lymphocytes of women.     

低剂量氢醌诱导hPARP-1蛋白正常及缺陷细胞适应性反应研究

目的观察人胚胎肺成纤维细胞（HLF）正常及缺陷细胞在低剂量氢醌（hydroquinone，HQ）处理后能否诱导适应性反应，探讨PARP-1蛋白缺陷与正常细胞诱导适应性反应与微核形成及细胞周期变化的关系，进一步阐明适应性反应形成机制。方法用低剂量HQ预处理细胞后，观察细胞和DNA对大剂量HQ攻击的适应性反应，从微核率及核异常率、细胞周期等方面测定细胞变化情况。结果在细胞整体活力水平，0．001～0．050μmol／L HQ预处理可以提高细胞对攻击剂量80．0μmol／L的耐受性；HLF、转染绿色荧光蛋白真核表达载体的HLF（HLFC）和转染hPARP-1基因反义RNA真核表达载体的HLF（HLFP）细胞经HQ低剂量预处理及大剂量攻击后，各剂量组不同程度出现含微核和核异常细胞，G1、G2、S期细胞数分布均不相同。与同种细胞仅大剂量攻击比较，0—0．050μmol／L HQ预处理的HLF，HLFC及HLFP细胞微核率及核异常率差异均有统计学意义（P〈0．05）。HQ预处理的HLF和HLFC细胞均出现G2期阻滞；HLFP细胞表现为G2期阻滞，1．000、2．000μmnol／L出现G1期阻滞。结论在低剂量HQ作用下，hPARP-1蛋白缺陷细胞和正常细胞一样有适应性反应，但低于正常细胞，说明hPARP-1蛋白在细胞适应性反应方面起重要作用，适应性反应与细胞周期调控等有关。     

非整倍体毒剂和染色体断裂剂的FCM微核检测区分方法研究

目的研究流式细胞术（flow cytometry，FCM）微核检测筛选非整倍体毒剂和染色体断裂剂的方法。方法采用CD71荧光抗体和碘丙啶（PI）双染色，通过FCM检测环磷酰胺（CP）和秋水仙素（COL）诱导的NIH小鼠外周血含微核网织红细胞的PI荧光强度，比较它们与二倍体细胞PI荧光强度中位数的比值，以探索通过FCM微核检测筛选非整倍体毒剂和染色体断裂剂的方法。结果染色体断裂剂CP诱导的含微核网织红细胞与二倍体细胞PI荧光强度中位数的比值较低，非整倍体毒剂COL诱导的含微核网织红细胞与二倍体细胞PI荧光强度中位数的比值较高，两者间差异有统计学意义（P〈0．01）。结论通过FCM检测微核PI染色强度，可初步判断诱导微核形成的因素是否具有染色体断裂剂和非整倍体毒剂毒性。     

停服棉酚后外周血微核淋巴细胞形态学观察及其形成机理的探讨

停服棉酚2个月和11个月的男子与未服棉酚的对照男子各15例,采用外周血微量培养法,检查了外周血微核和双核淋巴细胞。结果表明,停服棉酚后2个月的微核细胞出现率比11个月略高,但比对照组显著为高(P<0.05)。双核淋巴细胞出现率,2个月的高于一般正常值。所见微核分二类:无小核型和带小核型。有的微核有核仁样结构,在分裂前期细胞中可见微核多由几条乃至十几条染色或其断片样结构所组成。还发现一个有22个微核样结构的淋巴细胞。不仅主核可以产生微核,微核也可能产生小微核;主核和微核都可能以“核吐”方向形成微核和小微核,本文首次表明服棉酚后人外周血淋巴细胞微核具有核仁样结构。提示棉酚有可能引起基因碎裂或影响纺锤体结构。     

维胺酸对实验性口腔癌阻断作用的研究

目的观察维胺酸对实验性口腔癌的阻断作用方法以DMBA诱导的金黄地鼠口腔癌为模型用维胺酸进行治疗结果维胺酸对癌前病变有明显的阻断作用各治疗组与对照组相比均有显著性差异同时发现维胺酸可降低口腔粘膜细胞微核细胞率结论维胺酸对DMBA引起的粘膜组织DNA损伤有保护作用对实验性口腔有阻断作用     

Antigenotoxic effect of Saccharomyces cerevisiae on the damage produced in mice fed with aflatoxin B1 contaminated corn

The potential of Saccharomyces cerevisiae (Sc) was evaluated for reducing the micronucleated normochromatic erythrocytes (MNNE) rate in mice fed AFB₁ contaminated corn. The study included two groups fed AFB₁ contaminated corn (0.4 and 0.8 mg/kg), a control fed uncontaminated corn, another group fed uncontaminated corn and 0.3% of Sc (1 × 10⁸ live cells/g), and two groups fed AFB₁ contaminated corn (0.4 and 0.8 mg/kg) plus 0.3% Sc. Weight and MNNE were determined weekly for six weeks. Subsequently, the same determinations were made for another three-week period, but in mice receiving only a normal diet, without AFB₁ and Sc. Results in the first period revealed the following: control and Sc fed mice had similar constant weight increase, and low MNNE rate; mice fed only AFB₁ showed weight decrease and significant MNNE increase; finally, Sc improved weight gain and reduced MNNE produced by AFB₁. In the second period, results exhibited a tendency similar to that of the previous phase in the control and Sc fed mice; the weight and MNNE values improved in the other groups. We also determined the capacity of Sc for adsorbing and modifying the mycotoxin structure. The mixture was filtered to obtain two phases, and AFB₁ content was measured. Sc revealed a potent adsorbent capacity; however, chromatographic determination suggested no structural modification.     

苯中毒、石棉肺和有害气体中毒患者体细胞及生殖细胞的遗传损伤

目的对苯中毒、石棉肺、有害气体中毒者体细胞及生殖细胞的遗传损伤程度进行比较，为职业病防护与生殖健康研究提供依据。方法用常规法检测174名职业病患者（包括48例苯中毒、71例石棉肺、55例有害气体中毒）及80名健康人员的外周血淋巴细胞染色体畸变率和微核发生率，并取男性精液行精子畸形率与突变检测。结果3组患者染色体畸变率、微核发生率和精子畸形率依次为：苯中毒患者0．4％、1．52‰、（62±14）％；石棉肺患者0．51％、2.31‰、（41±7）％；有害气体中毒患者0．42％、1．55‰、（48±8）％，均明显高于对照组[0．20％、0．34‰、（27±5）％]，差异有统计学意义（P〈0．05）。石棉肺组的染色体畸变率和微核发生率高于其他组，但无统计学意义（P〉0．05）；苯中毒组的精子畸形率高于其他组，差异具有统计学意义（P〈0．05）。此外，在苯中毒患者精子中检测到了遗传物质的新突变。结论苯中毒、石棉肺、有害气体中毒者不仅存在体细胞遗传物质的损伤，还可能发生生殖细胞的遗传突变。     

Comparison of micronuclei induction for X-ray and ultrasound exposures of Vicia faba root meristem cells

X-irradiation (200R) but not ultrasound (1.1 MHz, 8 W/cm² peak, 1 min continuous exposure) induced micronuclei formation in root meristem cells of Vicia faba 6–36 hr post-exposure.     

Inhibition of nucleotide excision repair (NER) by microcystin-LR in CHO-K1 cells

Microcystin-LR (MC-LR), a potent inhibitor of PP1 and PP2A protein phosphatases, is related to tumor promotion and initiation. Although the genotoxic properties of this toxin have been extensively investigated with a variety of non-mammalian and mammalian test systems, the existing results are contradictory. Based on our previous results regarding the impact of MC-LR on the processes of DNA repair we decided to examine in greater detail its effect on the capacity of nucleotide excision repair (NER). CHO-K1 cells were pre-treated with increasing doses of MC-LR (1, 10 and 20 μg/ml) and then exposed to UV radiation (25 J/m²). Apoptosis was analyzed to exclude the possibility of false positive results in the comet assay. The results suggest that MC-LR targets the nucleotide excision repair mechanisms by interference with the incision/excision phase as well as the rejoining phase of NER and leads to an increased level of UV-induced cytogenetic DNA damage in CHO-K1 cells.