姜黄素拮抗亚砷酸钠所致的DNA链断裂损伤

目的观察姜黄素对亚砷酸钠诱发小鼠体内免疫器官细胞DNA链断裂损伤的拮抗作用。方法用单细胞凝胶电泳法。结果亚砷酸钠单独染毒后的DNA链断裂损伤的高峰期各器官不同,脾脏为染毒后1 h,胸腺和骨髓在染毒后3 h。姜黄素拮抗亚砷酸钠引起的各器官DNA链断裂损伤的作用在高峰期明显,表现为彗星细胞百分比降低,并有量效关系。结论姜黄素可以预防亚砷酸钠诱发的小鼠脾脏、胸腺和骨髓细胞的DNA链断裂损伤。     

纳米银对HL-7702肝细胞DNA的损伤作用

目的探讨纳米银对HL-7702肝细胞DNA的损伤效应。方法设对照组、微米银组和纳米银组,微米银和纳米银10,25,50,100,250mg·L-1对HL-7702肝细胞进行染毒,24h后用单细胞凝胶电泳技术检测HL-7702细胞DNA的损伤程度,用CASP软件分析彗星图像,并计算尾部DNA百分率和尾矩。结果与对照组和微米银组相比,纳米银染毒后HL-7702肝细胞DNA损伤效应明显增强;随纳米银染毒浓度的升高,HL-7702肝细胞尾部DNA百分率和尾矩均呈逐渐升高趋势;与对照组相比,染毒剂量≥25mg·L-1时,尾部DNA百分率及尾矩则显著升高(P<0.05,P<0.01)。结论纳米银可导致HL-7702肝细胞DNA损伤,微米银无明显的损伤作用。     

抗氧化剂在抑制紫外线所致DNA损伤中的作用

抗氧化剂在抑制紫外线所致ＤＮＡ损伤中的作用鄂晓飞刘扬李晶王秉贤国家自然科学基金资助项目中国医科大学环境卫生教研室（沈阳１１０００１）随着臭氧层的破坏，研究紫外线的有害作用，特别是致癌作用已成为环境医学领域中的重要课题。紫外线致皮肤癌的传统理论认为：角...     

应用彗星试验检测乌头类生物碱致细胞DNA损伤作用

目的:研究乌头类生物碱对细胞DNA的损伤作用,以期在分子水平进一步阐明乌头类生物碱的毒效作用特征及其分子机制.方法:以500、100、50和10μg·mL(-1)乌头碱、次乌头碱或新乌头碱分别染毒HepG2细胞1.5 h,应用24孔板彗星试验检测细胞DNA损伤.结果:乌头类生物碱作用组细胞平均拖尾长度和拖尾细胞率与生物碱浓度存在剂量反应关系,且100和50μg·mL(-1)作用组细胞平均拖尾长度与阴性对照组之间差异具有统计学意义(P<0.05).结论:乌头类生物碱具有细胞DNA损伤作用.     

彗星试验在检测甲氨蝶呤对小鼠精子DNA损伤中的应用

精子DNA损伤对人类生殖及其下一代健康的影响已越来越引起人们的重视,引起精子DNA损伤的因素很多,例如放射线、H2O2、化学药物等。甲氨蝶呤(Methotrexate,MTX)是一种二氢叶酸还原酶(dihydrofolate reductase,DHFR)抑制剂,常用于肿瘤的化疗,临床上长期低剂量应用MTX可引起月经不     

灵芝孢子粉对镉致雄性大鼠睾丸生殖细胞DNA氧化损伤的拮抗作用北大核心CSCD

目的研究镉致雄性大鼠睾丸生殖细胞DNA损伤及灵芝孢子粉的影响。方法 48只SD雄鼠,随机均分为4组:对照组、Cd组、灵芝孢子粉低拮抗组(GLSL+Cd)和灵芝孢子粉高拮抗组(GLSH+Cd)。灵芝孢子粉高低拮抗组分别灌胃1和0.5 g/kg灵芝孢子粉,对照组与Cd组灌胃等量生理盐水,1次/d。Cd组、GLSL+Cd和GLSH+Cd组腹腔注射Cd Cl22 mg/kg,隔天1次。对照组腹腔注射等量生理盐水。60 d后分两批处死,间隔为30 d。硫代巴比妥酸(TBA)法和BCA法分别测定丙二醛(MDA)含量和蛋白浓度,WST-1法测定超氧化物歧化酶(SOD)活力,单细胞凝胶电泳检测睾丸细胞DNA损伤(测定慧尾长、慧尾DNA百分含量及Olive尾矩)。结果 (1)与对照组比较,Cd组、GLSL+Cd组体重、睾丸重均降低,差异均有统计学意义(P<0.05)。(2)与Cd组比较,GLSL+Cd组、GLSH+Cd组睾丸组织MDA含量降低,SOD活力增加,DNA损伤程度均较低,差异均有统计学意义(P<0.05)。但GLSH+Cd组DNA损伤程度高于GLSL+Cd组,差异有统计学意义(P<0.05)。结论灵芝孢子粉对镉致雄性大鼠睾丸细胞DNA损伤有保护作用,但是发挥作用的最优剂量和时间还需要进一步探索。     

精液标本DNA损伤检测中影响因素的探讨

为探讨一种稳定的单细胞凝胶电泳的试验方法(又称彗星试验)，对110份精液标本按以下因素进行对比分析：①精液标本采集后不同处理、保存方法；②标本采集后不同保存时间；③不同电泳条件。结果表明，精液稀释后4℃放置与原液室温放置后3h、5h的彗星细胞率显著增加，而原液4℃放置对彗星发生率的影响最小(P&;lt;0．01)；电泳时电压与电流对彗星发生率有较明显的影响，当恒压12V不稳流时彗星发生率最低(P&;lt;0．05)；电泳液的碱性pH浓度对彗星发生率有一定影响，但无统计学意义；3种不同盖玻片之间的差异对彗星发生率的影响不大。结论：影响彗星试验结果的因素很多，不同保留时间、方法、电泳条件是最重要的因素，值得重视。     

用单细胞凝胶电泳检测砷,汞,铅致DNA损伤的研究

应用ＳＣＧＥ方法体外检测ＮａＡｓＯ２、ＨｇＣｌ２、Ｐｂ（ＮＯ３）２对人外周血淋巴细胞造成的ＤＮＡ损伤。结果表明，ＳＣＧＥ方法非常灵敏，能检测到很低剂量的ＮａＡｓＯ２和ＨｇＣｌ２所引起人外周血淋巴细胞的ＤＮＡ断裂，而且该法还具有快速、花费少等优点，值得推广使用     

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。     

Protective role of curcumin against nicotine-induced genotoxicity on rat liver under restricted dietary protein

Nicotine, the well known addictive chemical of tobacco and active medication for several diseases, has proven to be a potential genotoxic compound. Although it is absorbed through lungs with smoking and mainly metabolized in liver, its effect on liver injuries is not clear. This study was designed to evaluate the genotoxicity of nicotine and corresponding the protective role of curcumin against nicotine on liver of female populations particularly who used tobacco but deprived of healthy diet. The effects were investigated by measurement of total DNA concentration of liver tissues and Comet assay of liver tissue DNA damage of female rats maintained under normal and restricted protein diets. Total DNA contents in the liver tissues were observed to decrease more significantly (P<0.001) by nicotine in both dietary conditions. Significant (P<0.01) increase of total DNA content in normal dietary condition and more significant (P<0.001) increase of total DNA content in protein restricted condition of the liver tissues were observed due to curcumin supplementations. Highly significant (P<0.001) DNA damages (37% in normal diet and 56% in protein restricted diet) of the liver tissues were observed due to nicotine treatment. Curcumin reduced the nicotine-induced DNA damage percentage of the liver tissues more significantly (P<0.001) in protein restricted condition. Curcumin proved its potential to function against genotoxic effect by reducing the DNA damage activity of nicotine and minimized the percentage of DNA damage (50-60%) in protein restricted dietary condition. The degree of nicotine-induced genotoxicity therefore can be effectively compensated by the protective effect of curcumin in protein stress condition.     

Evaluation of various glyphosate concentrations on DNA damage in human Raji cells and its impact on cytotoxicity

Glyphosate is a highly used active compound in agriculturally based pesticides. The literature regarding the toxicity of glyphosate to human cells has been highly inconsistent. We studied the resulting DNA damage and cytotoxicity of various glyphosate concentrations on human cells to evaluate DNA damaging potential. Utilizing human Raji cells, DNA damage was quantified using the comet assay, while cytotoxicity was further analyzed using MTT viability assays. Several glyphosate concentrations were assessed, ranging from 15 mM to 0.1 μM. We found that glyphosate treatment is lethal to Raji cells at concentrations above 10 mM, yet has no cytotoxic effects at concentrations at or below 100 μM. Treatment concentrations of 1 mM and 5 mM induce statistically significant DNA damage to Raji cells following 30–60 min of treatment, however, cells show a slow recovery from initial damage and cell viability is unaffected after 2 h. At these same concentrations, cells treated with additional compound did not recover and maintained high levels of DNA damage. While the cytotoxicity of glyphosate appears to be minimal for physiologically relevant concentrations, the compound has a definitive cytotoxic nature in human cells at high concentrations. Our data also suggests a mammalian metabolic pathway for the degradation of glyphosate may be present.     

Myricetin, quercetin, (+)-catechin and (−)-epicatechin protect against N-nitrosamines-induced DNA damage in human hepatoma cells

The aim of this study was to investigate the protective effect of myricetin, quercetin, (+)-catechin and (−)-epicatechin, against N-nitrosodibutylamine (NDBA) and N-nitrosopiperidine (NPIP)-induced DNA damage in human hepatoma cells (HepG2). DNA damage (strand breaks and oxidized purines/pyrimidines) was evaluated by the alkaline single-cell gel electrophoresis or Comet assay. (+)-Catechin at the lowest concentration (10 μM) showed the maximum reduction of DNA strand breaks (23%), the formation of endonuclease III (Endo III, 19–21%) and formamidopyrimidine-DNA glycosylase (Fpg, 28–40%) sensitive sites induced by NDBA or NPIP. (−)-Epicatechin also decreased DNA strand breaks (10 μM, 20%) and the oxidized pyrimidines/purines (33–39%) induced by NDBA or NPIP, respectively. DNA strand breaks induced by NDBA or NPIP were weakly reduced by myricetin at the lowest concentration (0.1 μM, 10–19%, respectively). Myricetin also reduced the oxidized purines (0.1 μM, 17%) and pyrimidines (0.1 μM, 15%) induced by NDBA, but not the oxidized pyrimidines induced by NPIP. Quercetin did not protect against NDBA-induced DNA damage, but it reduced the formation of Endo III and Fpg sensitive sites induced by NPIP (0.1 μM, 17–20%, respectively). In conclusion, our results indicate that (+)-catechin and (−)-epicatechin at the concentrations tested protect human derived cells against oxidative DNA damage effects of NDBA and NPIP. However, myricetin at the concentrations tested only protects human cells against oxidative DNA damage induced by NDBA and quercetin against oxidative DNA damage induced by NPIP.     

Combusted but not smokeless tobacco products cause DNA damage in oral cavity cells

The aim of this work was to investigate genomic DNA damage in human oral cavity cells after exposure to different tobacco product preparations (TPPs). The oral carcinoma cell line 101A, gingival epithelial cells HGEC, and gingival fibroblasts HGF were exposed to TPM (total particulate matter from 3R4F cigarettes), ST/CAS (2S3 smokeless tobacco extract in complete artificial saliva), and NIC (nicotine). Treatments were for 24 h using TPM at its EC-50 doses, ST/CAS and NIC at doses with equi-nicotine units, and high doses for ST/CAS and NIC. Comet assays showed that TPM, but not ST/CAS or NIC, caused substantial DNA breaks in cells; only the high ST/CAS dose caused weak DNA damage. These results were confirmed by immunofluorescence for γ-H2AX protein. These data revealed that the combusted TPP caused substantial DNA damage in all cell types, whereas the two non-combusted TPPs exerted no or only minimal DNA damage. They support epidemiologic evidence on the relative risk associated with consumption of non-combusted versus combusted tobacco products, and help to understand potential genotoxic effects of such products on oral cavity cells.     

DNA damage in leukocytes of mice treated with copper sulfate

Single stranded DNA breaks induced by copper sulfate (CuSO₄) in mice has been studied in vivo using Alkaline Single Cell Gel Electrophoresis (Comet assay). Mice were administered orally with doses of 0, 1.25, 2.50, 5.00, 7.50, 10.00 and 12.50 mg/kg body weight (b.wt.) of CuSO₄ respectively. The samples of whole blood were collected at 24, 48, 72 h, first week and second week post-treatment and the assay was carried out to determine single strand DNA breaks as represented by comet tail-length. In addition, the sample was used to study the repair efficiency by incubating the samples with RPMI medium for 2 h. Results indicated a significant DNA damage at all the doses after treatment with CuSO₄ when compared to controls showing a clear dose-dependent response (p < 0.05). A gradual decrease in the tail-lengths from 48 h post-treatment was observed and by second week, the values returned to control levels at all doses. The study on the repair efficiency indicated that mice treated with all the doses of CuSO₄ showed decrease in mean comet tail-length indicating repair efficiency capacity but less when compared to those of controls. The study also reveals that comet assay is a sensitive and rapid method for detecting DNA damage caused by trace metals such as copper (Cu).     

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.     

Modulation of ethoxyquin genotoxicity by free radical scavengers and DNA damage repair in human lymphocytes

N-tert-butyl-α-phenylnitrone (PBN) and its new derivative N-(Pyridine-4-ylmethylidene)-2-carboxy-tert-butylamine N-oxide (PBNC) were synthesized and used to modulate ethoxyquin (1,2-dihydro-6-ethoxy-2,2,4-trimethylquinoline, EQ) genotoxicity. Ethoxyquin, an antioxidant used mainly as a preservative in animal feeds, was shown to cause DNA breaks in human lymphocytes. The aim of the study was to evaluate the involvement of free radicals in the genotoxicity of EQ and its modulation by cellular repair systems. Human lymphocytes treated with EQ (10–50 μM) and nitrone free radical scavengers (100 μM) were tested with the comet assay. It was shown that both PBN and PBNC reduced the level of EQ-induced DNA damage, but PBN was slightly more effective. The modulation of the level of DNA damage was also observed as a result of DNA repair by cellular repair systems. Moreover, induction of oxidized bases by ethoxyquin was showed; lymphocytes exposed to ethoxyquin and treated with endonuclease III (Endo III) and formamidopyrimidine-DNA glycosylase (FpG), enzymes recognizing oxidized bases, displayed greater extent of DNA damage than those not treated with the enzymes.     

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。     

甲氨蝶呤治疗类风湿关节炎对外周血淋巴细胞DNA的损伤

目的研究多次低剂量应用甲氨蝶呤治疗类风湿关节炎(RA)病人造成的淋巴细胞DNA的损伤,并探讨四氢叶酸对该损伤的保护作用。方法应用甲氨蝶呤10mg/次,每周1次,共8周,同时在应用甲氨蝶呤4h后应用相同剂量的甲酰四氢叶酸;用单细胞凝胶电泳方法检测其外周血淋巴细胞DNA的损伤及修复情况。结果单用甲氨蝶呤组细胞尾长及拖尾频率与对照组相比差异均有显著性,而同时应用等量的甲酰四氢叶酸其细胞尾长及拖尾频率与对照组相比差异无显著性。结论单细胞凝胶电泳技术可敏感地检测RA病人多次应用低剂量甲氨蝶呤造成的外周血淋巴细胞DNA损伤,并能反映甲酰四氢叶酸对甲氨蝶呤所致的DNA损伤的保护作用,为探讨甲氨蝶呤治疗RA引起的不良反应机制提供了线索。