二氨胺基酸对V79细胞DNA损伤效应的研究

我们采用单细胞凝胶电泳新技术和ＳＣＥ试验研究了８３－１除草剂的主要代谢产物２，４－二氯－６－胺基酚（ＤＣＡＰ）对Ｖ７９细胞的ＤＮＡ损伤作用。结果表明，ＤＣＡＰ浓度≥５０μｇ／ｍｌ时，细胞出现明显的ＤＮＡ迁移和姐妹染色单体交换，说明ＤＣＡＰ是ＤＮＡ损伤剂，结合前期研究结果推断，６位硝基还原成胺基是该除草剂在体内活化致癌的基本途径，结果还表明，单细胞凝胶电泳经ＳＣＥ试验更灵敏，可能是研究环境低剂量暴露     

彗星试验检测石棉对V79细胞DNA损伤的研究

目的 研究石棉悬液和浸泡过滤上清液对V79细胞的DNA损伤情况，以进一步探讨石棉致癌机制。方法 用彗星试验检测3种石棉悬液和浸泡过滤上清液对V79细胞的DNA损伤情况。同时设立阴性对照组。结果 石棉悬液各剂量组细胞DNA的迁移距离与阴性对照组比较，差异均有显著性（P＜0．05或P＜0．01），且均有确切的剂量反应关系。结论 不仅石棉纤维对V79细胞DNA有物理损伤作用，而且其浸泡过滤上清液对V79细胞DNA有化学损伤作用。     

关木通两种提取液对V79细胞DNA的损伤作用

目的 探讨关木通对DNA的损伤作用。方法 应用单细胞凝胶电泳技术（彗星实验）研究中药关木通的两种提取液对中国仓鼠肺成纤维细胞（V79）的DNA损伤情况。结果 关木通的两种提取液在一定浓度下均能导致V79细胞产生彗星现象，并且存在的剂量-反应关系。结论 提示关木通过V79细胞DNA具有损伤作用。     

青蒿素对肿瘤细胞DNA的损伤作用

目的:研究青蒿素对肿瘤细胞DNA的损伤作用。方法:体外培养人白血病K562细胞,MTT法测定IC50,应用单细胞凝胶电泳(SCGE)检测细胞核DNA的损伤。结果:青蒿素处理K562细胞IC50为1.5×10-5mol/L,1×10-5mol/L青蒿素处理细胞24h后可引起细胞核DNA的损伤。结论:青蒿素造成肿瘤细胞DNA的损伤,抑制肿瘤细胞生长。     

阿莫西林对人HepG2细胞DNA有短暂损伤作用

目的 为了探讨阿莫西林对人HepG2细胞DNA是否有损伤作用.方法 培养的人HepG2细胞经不同浓度(2、10、50和250μmol/L)阿莫西林处理1h或经50μmol/L阿莫西林处理不同时间(20、40、60、120和180min)后,运用单细胞凝胶电泳(SCGE)技术结合彗星图像软件(CASP)分析细胞尾部DNA百分率(tail DNA%)变化情况.结果 不同浓度阿莫西林处理后结果显示,HepG2细胞尾部DNA百分率明显升高,至50μmol/L阿莫西林时达到最高值,各浓度处理组与不处理对照组相比差异皆有显著性(P<0.01);而同一浓度(50μmol/L)阿莫西林处理不同时间后结果显示,HepG2细胞尾部DNA百分率逐渐升高,至1h处理时间点时达到最高值,其后随着处理时间延长HepG2细胞尾部DNA百分率逐渐降低.结论 阿莫西林对人HepG2细胞DNA有短暂损伤作用,阿莫西林诱发的HepG2细胞DNA损伤可能随时间延长逐渐被HepG2细胞本身修复除去.     

低剂量甲氨蝶呤对DNA损伤的研究

甲氨蝶呤(methotrexate MTX)是二氢叶酸还原酶抑制剂，近年来低剂量的甲氨蝶呤广泛用于治疗类风湿关节炎(rheumatoid arthritis，RA)及其他慢性炎症性疾病。关于MTX的抗炎机制及引起不良反应的机制仍不十分清楚，它可部分地解释为对二氢叶酸的拮抗作用，但关于这方面的研究很少。彗星试验(comet assay)     

砷对小鼠骨髓细胞DNA的损伤作用

了解砷对体内细胞ＤＮＡ的损伤作用及其机制。「方法」在小鼠饮水加入Ａｓ２Ｏ３喂养６个月,采用单细胞凝胶电泳技术对骨髓细胞ＤＮＡ断裂进行了分析。「结果高剂量组（１２．５ｍｇ／Ｌ）小鼠骨髓细胞ＤＮＡ的迁移度和迁移率显著高于阴性对照组,Ｐ〈０．０５;中、低剂量组小鼠骨髓细胞ＤＮＡ的迁移度和迁移率与性对照组无显著差异。     

铅对妊娠期及新生期大鼠神经细胞DNA的损伤

目的 环境中低水平的铅暴露一般不会引起典型的铅中毒，但有可能对神经系统产生毒性作用，尤其是对职业妇女的健康和儿童的智力发育的影响仍是比较严重；妊娠期及新生期是神经组织发育的关键时期，铅可通过胎盘屏障和血脑屏障，直接进入胎儿和新生儿的大脑，对中枢神经系统造成不可逆的损害。现目的进一步揭示铅的神经毒性作用机制。     

铅对小鼠睾丸细胞DNA损伤作用研究

目的:通过建立亚慢性铅中毒动物模型探讨醋酸铅对雄性小鼠睾丸细胞DNA的损伤,为进一步了解其毒性作用机制提供科学依据。方法:将45只雄性小鼠分为0.2%、0.4%染铅组及空白对照组,每组各5只。实验组醋酸铅溶于去离子水中供小鼠自由摄取,空白对照组饮用自来水。分别于第2、4、6周分别处死动物,用单细胞凝胶电泳实验(彗星实验)检测小鼠睾丸细胞DNA损伤情况。结果:醋酸铅染毒后小鼠睾丸细胞DNA单链断裂,出现彗星状拖尾。无论是拖尾细胞的百分率,DNA迁移的长度,还是olive尾矩与空白对照组相比其差异具有极显著性(P<0.01),并且随着醋酸铅染毒浓度和时间的增加DNA的损伤越重,呈现出时间-效应关系。但0.2%与0.4%各周染毒组的拖尾细胞百分率、彗星尾长、olive尾矩的差异并无显著性(P>0.05)。结论:醋酸铅可诱导睾丸生殖细胞DNA损伤,并且其损伤作用呈现出时间依赖性。     

血红素氧化酶在软骨藻酸对细胞DNA损伤中的作用

目的　　研究血红素氧化酶 (hemeoxygenase ,HO)系统在软骨藻酸 (domoicacid ,DA)对H4细胞DNA损伤中的作用。方法　应用单细胞凝胶电泳法 (SCGE)分别测定 0、0 0 64、0 64和 6 4μmol/LDA单独及与HO系统的活性阻断剂ZnPP 9(10 - 5mol/L)联合作用于H4细胞 6、12、2 4和 48h后彗星拖尾细胞率及拖尾尾长。结果　彗星拖尾细胞率 :中剂量和高剂量组各时间点均比对照组高 ,差异有显著性 (P <0 0 5 )。中剂量 +阻断剂组各时间点均相应高于中剂量组 ,差异有显著性 (P <0 0 5 )。彗星拖尾尾长 :中剂量组 12、2 4和 48h比对照组长 ,2 4、48h比低剂量组长 ,差异均有显著性 (P<0 0 5 )。高剂量组各时间点均比对照组、低剂量组和中剂量组长 ,差异有显著性 (P <0 0 5 )。高剂量 +阻断剂组和中剂量 +阻断剂组 2 4、48h分别高于高剂量和中剂量组 ,差异有显著性 (P <0 0 5 )。尾长 时间作Regression分析 ,各剂量组r差异值均有显著性 (P <0 0 1)。结论　软骨藻酸能诱导H4细胞DNA损伤 ,HO系统对这种损伤有一定的保护作用。     

Oxidative DNA lesions in V79 cells mediated by pentachlorophenol metabolites

 Incubation of the pentachlorophenol (PCP) metabolites, tetrachloro-p-benzoquinone (chloranil, TCpBQ), tetrachloro-p-hydroquinone (TCpHQ) and tetrachloro-o-benzoquinone (TCoBQ) with V79 Chinese hamster cells led to a significant enhancement of the amount of 8-hydroxydeoxyguanosine (8-OH-dG) in DNA. With PCP itself and the metabolite tetrachloro-o-hydroquinone (TCoHQ) no distinct induction of this lesion could be observed. The average yields of 8-OH-dG were about 2–2.5 times above background levels. In addition, TCpBQ and TCpHQ were able to generate DNA single-strand breaks, while PCP, TCoHQ and TCoBQ failed to induce this lesion. All incubations were performed for 1 h without exogenous metabolic activation and concentrations were 25 μM of the respective agent. It is concluded that these metabolites may contribute to the carcinogenicity of PCP observed in mice, by generating reactive oxygen species (ROS) through their redox cycling properties. Received: 20 September 1995/Accepted: 14 November 1995     

单细胞凝胶电泳技术在甲基汞对小鼠胸腺淋巴细胞DNA损伤中的应用

目的 探讨甲基汞对小鼠胸淋巴细胞DNA损伤的作用。方法 采用单细胞凝胶电泳技术进行检测。结果 1／200－1／2LD。剂量组的甲基汞均可引起淋巴细胞DNA不同程度电泳迁移；A组（1／200LD50）、B组（1／20LD50）、C组（1／2LD50）DNA平均迁移长工与对照组之间差异有显著性（P＜0．05），并且C组与A、B两组之间差异也有显著性（P＜0．001）；B组尾直径／头直径、尾面积／总面积之比均与A组差异有显著性（P＜0．05）、C组各项之比均与A、B组差异有显著性（P＜0．05）。结论 甲基汞引起DNA链断裂损伤，随着甲基汞剂量的增加，淋巴细胞DNA损伤加重。     

Evaluating the combinative effects on human lymphocyte DNA damage induced by ultraviolet ray C plus 1.8 GHz microwaves using comet assay in vitro

The objective of this study was to observe whether 1.8 GHz microwaves (MW) (SAR, 3 W/kg) exposure can influence human lymphocyte DNA damage induced by ultraviolet ray C (UVC). The lymphocytes, which were from three young healthy donors, were exposed to 254 nm UVC at the doses of 0.25, 0.5, 0.75, 1.0, 1.5 and 2.0 J m(-2), respectively. The lymphocytes were irradiated by 1.8 GHz MW (SAR, 3 W/kg) for 0, 1.5 and 4 h. The combinative exposure of UVC plus MW was conducted. The treated cells were incubated for 0, 1.5 and 4 h. Finally, comet assay was used to measure DNA damage of above treated lymphocytes. The results indicated that the difference of DNA damage induced between MW group and control group was not significant (P>0.05). The MTLs induced by UVC were 1.71+/-0.09, 2.02+/-0.08, 2.27+/-0.17, 2.27+/-0.06, 2.25+/-0.12, 2.24+/-0.11 microm, respectively, which were significantly higher than that (0.96+/-0.05 microm) of control (P<0.01). MTLs of some sub-groups in combinative exposure groups at 1.5-h incubation were significantly lower that those of corresponding UVC sub-groups (P<0.01 or P<0.05). However, MTLs of some sub-groups in combinative exposure groups at 4-h incubation were significantly higher that those of corresponding UVC sub-groups (P<0.01 or P<0.05). In this experiment it was found that 1.8 GHz (SAR, 3 W/kg) MW exposure for 1.5 and 4 h did not enhance significantly human lymphocyte DNA damage, but could reduce and increase DNA damage of human lymphocytes induced by UVC at 1.5-h and 4-h incubation, respectively.     

Mitochondrial and nuclear DNA damage induced by curcumin in human hepatoma G2 cells.

Curcumin is extensively used as a spice and pigment and has anticarcinogenic effects that could be linked to its antioxidant properties. However, some studies suggest that this natural compound possesses both pro- and antioxidative effects. In this study, we found that curcumin induced DNA damage to both the mitochondrial and nuclear genomes in human hepatoma G2 cells. Using quantitative polymerase chain reaction and immunocytochemistry staining of 8-hydroxydeoxyguanosine, we demonstrated that curcumin induced dose-dependent damage in both the mitochondrial and nuclear genomes and that the mitochondrial damage was more extensive. Nuclear DNA fragments were also evident in comet assays. The mechanism underlies the elevated level of reactive oxygen species and lipid peroxidation generated by curcumin. The lack of DNA damage at low doses suggested that low levels of curcumin does not induce DNA damage and may play an antioxidant role in carcinogenesis. But at high doses, we found that curcumin imposed oxidative stress and damaged DNA. These data reinforce the hypothesis that curcumin plays a conflicting dual role in carcinogenesis. Also, the extensive mitochondrial DNA damage might be an initial event triggering curcumin-induced cell death.     

苯并(a)芘引起鼠胸腺细胞DNA损伤及其机制

目的研究苯并(a)芘引起的鼠胸腺细胞DNA损伤及其机制。方法在加或不加代谢活化系统(S9)条件下,运用单细胞凝胶电泳技术检测不同浓度苯并(a)芘所致的鼠胸腺细胞DNA损伤,同时观察抗氧化剂N-乙酰-L-半胱氨酸对其损伤的影响;采用比色法测定不同浓度苯并(a)芘染毒后鼠胸腺细胞NO含量。结果10-4、10-5和10-6mol/L苯并(a)芘( S9)染毒后,鼠胸腺细胞DNA迁移距离分别为(42.14±5.23)(、25.36±2.96)和(18.78±1.72)μm,与溶剂对照组(11.25±0.92)μm相比,差异有显著性,阳性组加入抗氧化剂N-乙酰-L-半胱氨酸后DNA迁移距离明显缩短;而鼠胸腺细胞NO含量并无显著增加。结论苯并(a)芘可引起鼠胸腺细胞DNA损伤,其损伤与苯并(a)芘代谢产生的活性氧有关,而NO可能不参其损伤。     

Evaluation of genotoxic risk and oxidative DNA damage in mammalian cells exposed to mycotoxins,patulin and citrinin

Mycotoxins are fungal secondary metabolites with very diversified toxic effects in humans and animals. In the present study, patulin (PAT) and citrinin (CTN), two prevalent mycotoxins, were evaluated for their genotoxic effects and oxidative damage to mammalian cells, including Chinese hamster ovary cells (CHO-K1), human peripheral blood lymphocytes, and human embryonic kidney cells (HEK293). PAT, but not CTN, caused a significant dose-dependent increase in sister chromatid exchange (SCE) frequency in both CHO-K1 and human lymphocytes. PAT also elevated the levels of DNA gap and break in treated CHO-K1. In the single cell gel electrophoresis (SCGE) assay, exposure of HEK293 to concentrations above 15 microM of PAT induced DNA strand breaks; the tail moment values also greatly increased after posttreatment with formamidopyrimidine-DNA glycosylase (Fpg). This suggests that in human cells PAT is a potent clastogen with the ability to cause oxidative damage to DNA. However, no significant change in the tail moment values in CTN-treated cultures was found, suggesting that CTN is not genotoxic to HEK293. Incubation of HEK293 with CTN increased the mRNA level of heat shock protein 70 (HSP70), but not that of human 8-hydroxyguanine DNA glycosylase 1 (hOGG1). PAT treatment did not modulate the expression of either HSP70 or hOGG1 mRNA.