五指毛桃水提液对60Coγ射线致小鼠骨髓细胞DNA损伤的防护作用

目的 探讨五指毛桃水提液对60Coγ射线所致的小鼠骨髓细胞DNA损伤的防护作用.方法 40只SPF级♂小鼠随机分为5组:阴性对照组给予生理盐水,辐射模型组单纯接受照射,3个五指毛桃剂量组分别给予相当于生药5,10,20 g.kg-1.d-1五指毛桃水提液,连续灌胃7d.除阴性对照组外,所有小鼠接受全身一次性60Coγ射...     

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。     

单细胞凝胶电泳检测单细胞DNA损伤

遗传毒理学家主要关注的三大遗传学损伤 ,即基因突变、染色体畸变及染色体数目改变。这些损伤多因 DNA受损所致 ,其本质是相同的 ,区别在于其损伤的程度 [1 ]。由此DNA损伤与修复就成为生物医学领域特别是遗传毒理学及肿瘤学等领域的核心内容之一。传统的毒理学检测终点是组织病理学改变 ,过程繁琐且不理想。迄今为止检测DNA损伤与修复最敏感的终点是测量 DNA单链断裂 [2 ] 。本文所论述的单细胞凝胶电泳 (single cell gelelectrophoresis assay,SCGE) ,又称彗星实验 (comet assay)或微凝胶电泳 (m icrogel electrophoresis,MGE) ,…     

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。     

茶多酚对石英致肺巨噬细胞DNA损伤的保护作用

[目的] 探讨茶多酚对石英致大鼠肺巨噬细胞DNA损伤的保护作用.[方法] 将肺巨噬细胞分成生理盐水、石英、茶多酚及茶多酚+石英组.用单细胞凝胶电泳技术检测肺巨噬细胞彗星率出现和彗星尾长度.[结果] 低、中、高3种剂量的茶多酚+石英组的彗星出现率分别为66%、68%、67%,极显著低于石英组的78%(P<0.01);3种剂量的茶多酚加石英组彗星的尾长分别为12.6±2.2、13.6±1.17、12.9±2.6 μm,与石英组(18.7±2.7) μm 比较,极显著短于对照组(P<0.01).[结论] 茶多酚对石英致大鼠肺巨噬细胞DNA损伤有一定保护作用.     

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。     

硫芥对犬外周血淋巴细胞DNA损伤的作用

硫芥是典型的双功能烃化剂 ,进入体内后产生烃化作用 ,攻击的主要靶分子是ＤＮＡ。目前 ,单细胞凝胶电泳(ＳＣＧＥ)技术发展很快 ,国内、外将该法作为ＤＮＡ损伤检测的基本方法之一。先前我们用此法进行硫芥对人外周血淋巴细胞ＤＮＡ损伤的体外实验[1 ] ,本次选用犬外周血淋巴细胞 ,观察体内、外硫芥染毒后ＤＮＡ损伤的剂量效应与时间效应关系 ,为寻找研究硫芥细胞毒性作用及中毒早期敏感的检测方法提供实验依据。1　材料与方法1 1　主要仪器设备　奥林巴斯ＢＸ - 6 0显微镜、目测微尺(日本 )、电泳仪ＤＤＹ Ⅲ 6Ｂ、电泳槽ＤＤＹ Ⅲ 34Ａ…     

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。     

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     

低剂量的硒与镉联合作用对大鼠肝细胞DNA损伤的影响

目的 研究低剂量的亚硒酸钠和氯化镉联合作用对离体大鼠肝细胞DNA损伤的影响。方法 在2．185、4．375和8．750μmol／L的剂量条件下，亚硒酸钠和氯化镉联合作用，用单细胞凝胶电泳检测大鼠肝细胞DNA损伤。结果 2．185μmol／L的亚硒酸钠对2．185μmol／L的氯化镉引起的DNA损伤拮抗作用不明显，但有拮抗作用的趋势；4．375μmol／L亚硒酸钠对4．375μmol／L氯化镉引起的DNA损伤有明显的拈抗作用；而在8．750μmol／L的剂量下，亚硒酸钠与氯化镉存在相互拈抗的关系。结论 在硒和镉对大鼠肝细胞DNA损伤的联合作用中，较低剂量的亚硒酸钠对氯化镉没有拮抗作用，而在一定的剂量条件下，亚硒酸钠和氯化镉存在着相互拮抗的关系。     

Evaluation of DNA damage in patients with arsenic poisoning: urinary 8-hydroxydeoxyguanine

The relationship between arsenic exposure and DNA damage in patients with acute or chronic arsenic poisoning was analyzed. Urinary 8-hydroxydeoxyguanine (8-OHdG) concentrations were measured as an indication of oxidative DNA damage. A remarkable increase in 8-OHdG in the urine was observed in 60% of 52 patients with acute arsenic poisoning from the accidental oral intake of the arsenic trioxide. This was two- to threefold higher than levels in normal healthy subjects (n = 248). There was a clear relationship between arsenic concentrations in urine after acute poisoning and elevated levels of 8-OHdG. Levels of urinary 8-OHdG returned to normal within 180 days after the acute arsenic poisoning event. In patients chronically poisoned by the consumption of well water with elevated levels of arsenate [As(V)], elevated 8-OHdG concentrations in urine were also observed. A significant correlation between the 8-OHdG levels and arsenic levels in the urine was observed in 82 patients with chronic poisoning. Thus, evidence of oxidative DNA damage occurred in acute arsenic poisoning by arsenite [As(III)] and in chronic arsenic poisoning by As(V). In chronic poisoning patients provided low-arsenic drinking water, evidence of DNA damage subsided between 9 months and 1 year after the high levels of arsenic intake were reduced. The initial level of arsenic exposure appeared to dictate the length of this recovery period. These data indicate that some aspects of chronic and acute arsenic poisoning may be reversible with the cessation of exposure. This knowledge may contribute to our understanding of the risk elevation from arsenic carcinogenesis and perhaps be used in a prospective fashion to assess individual risk.     

黄芪皂苷对X线诱发骨髓间充质干细胞的基因损伤的保护作用

目的 研究黄芪皂苷(AS)对X线辐照骨髓间充质干细胞(BMSCs)增殖水平影响及其诱发DNA损伤的保护作用.方法 将细胞分为4组:空白组、AS组(50μg·mL-1 AS)、辐射组、辐射+AS组(50μg·mL-1 AS).药物干预3 d后,辐射组、辐射+AS组用2 Gy X线进行照射.用CCK-8法检测各组细胞的增殖...     

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。     

Metabolites of arsenic and increased DNA damage of p53 gene in arsenic plant workers

Recent studies have shown that monomethylarsonous acid is more cytotoxic and genotoxic than arsenate and arsenite, which may attribute to the increased levels of reactive oxygen species. In this study, we used hydride generation-atomic absorption spectrometry to determine three arsenic species in urine of workers who had been working in arsenic plants,and calculated primary and secondary methylation indexes. The damages of exon 5, 6, 8 of p53 gene were determined by the method developed by Sikorsky, et al. Results show that the concentrations of each urinary arsenic species,and damage indexes of exon 5 and 8 of p53 gene in the exposed population were significantly higher, but SMI was significantly lower than in the control group. The closely positive correlation between the damage index of exon 5 and PMI,MMA, DMA were found, but there was closely negative correlation between the damage index of exon 5 and SMI. Those findings suggested that DNA damage of exon 5 and 8 of p53 gene existed in the population occupationally exposed to arsenic. For exon 5, the important factors may include the model of arsenic metabolic transformation, the concentrations of MMA and DMA, and the MMA may be of great importance.     

An oxovanadium(IV) complex protects murine bone marrow cells against cisplatin-induced myelotoxicity and DNA damage

Cisplatin (CDDP) is one of the first-line anticancer drugs that has gained widespread use against various forms of human malignancies. But, the therapeutic outcome of CDDP therapy is limited due to its adverse effects including myelotoxicity and DNA damage which may lead to the subsequent risk of developing secondary cancer. Hence, in search of a suitable cytoprotectant, this study investigated the probable protective efficacy of an oxovanadium(IV) complex, namely oxovanadium(IV)-L-cysteine methyl ester complex (VC-IV) against CDDP-induced myelosuppression and genotoxic damage in the bone marrow cells of Swiss albino mice. CDDP was administered intraperitoneally (5?mg/kg b.w.) and VC-IV was administered orally (1?mg/kg b.w.) in concomitant and 7 d pretreatment schedule. Treatment with VC-IV in CDDP-treated mice significantly (p?p?p?p?相似文献   

Oxidative DNA damage and repair in children exposed to low levels of arsenic in utero and during early childhood: Application of salivary and urinary biomarkers

The present study aimed to assess arsenic exposure and its effect on oxidative DNA damage and repair in young children exposed in utero and continued to live in arsenic-contaminated areas. To address the need for biological specimens that can be acquired with minimal discomfort to children, we used non-invasive urinary and salivary-based assays for assessing arsenic exposure and early biological effects that have potentially serious health implications. Levels of arsenic in nails showed the greatest magnitude of difference between exposed and control groups, followed by arsenic concentrations in saliva and urine. Arsenic levels in saliva showed significant positive correlations with other biomarkers of arsenic exposure, including arsenic accumulation in nails (r = 0.56, P < 0.001) and arsenic concentration in urine (r = 0.50, P < 0.05). Exposed children had a significant reduction in arsenic methylation capacity indicated by decreased primary methylation index and secondary methylation index in both urine and saliva samples. Levels of salivary 8-OHdG in exposed children were significantly higher (~ 4-fold, P < 0.01), whereas levels of urinary 8-OHdG excretion and salivary hOGG1 expression were significantly lower in exposed children (~ 3-fold, P < 0.05), suggesting a defect in hOGG1 that resulted in ineffective cleavage of 8-OHdG. Multiple regression analysis results showed that levels of inorganic arsenic (iAs) in saliva and urine had a significant positive association with salivary 8-OHdG and a significant negative association with salivary hOGG1 expression.     

Persistence of DNA damage following exposure of human bladder cells to chronic monomethylarsonous acid

Malignant transformation was demonstrated in UROtsa cells following 52-weeks of exposure to 50 nM monomethylarsonous acid (MMA^III); the result was the malignantly transformed cell line, URO-MSC. URO-MSC cells were used to study the induction of DNA damage and the alteration of DNA repair enzymes in both the presence of MMA^III [URO-MSC(+)] and after subsequent removal of MMA^III [URO-MSC(−)] following chronic, low-level exposure. In the presence of MMA^III, URO-MSC(+) cells demonstrated a sustained increase in DNA damage following 12-weeks of exposure; in particular, a significant increase in DNA single-strand breaks at 12-weeks of exposure consistently elevated through 52 weeks. The persistence of DNA damage in URO-MSC cells was assessed after a 2-week removal of MMA^III. URO-MSC(−) cells demonstrated a decrease in DNA damage compared to URO-MSC(+); however, DNA damage in URO-MSC(−) remained significantly elevated when compared to untreated UROtsa and increased in a time-dependent manner. Reactive oxygen species (ROS) were demonstrated to be a critical component in the generation of DNA damage determined through the incubation of ROS scavengers with URO-MSC cells. Poly (ADP-ribose) polymerase (PARP) is a key repair enzyme in DNA single-strand break repair. URO-MSC(+) resulted in a slight increase in PARP activity after 36-weeks of MMA^III exposure, suggesting the presence of MMA^III is inhibiting the increase in PARP activity. In support, PARP activity in URO-MSC(−) increased significantly, coinciding with a subsequent decrease in DNA damage demonstrated in URO-MSC(−) compared to URO-MSC(+). These data demonstrate that chronic, low-level exposure of UROtsa cells to 50 nM MMA^III results in: the induction of DNA damage that remains elevated upon removal of MMA^III; increased levels of ROS that play a role in MMA^III induced-DNA damage; and decreased PARP activity in the presence of MMA^III.     

Oxidative activation of the human carcinogen chromate by arsenite: A model for synergistic metal activation leading to oxidative DNA damage

Human exposure to toxic metals and metalloids in the environment seldom occurs from a single pure compound. Most environmental exposure profiles are heterogeneous with co-exposure occurring coincident with multiple toxic metal species. This co-exposure to metals and metalloids in complex mixtures can result in a synergistic, additive or even depletive toxic response. The complexity of interactions presented by metal mixtures presents a need for convenient and sensitive methods to determine potential toxic responses from such co-exposure. We have studied the reaction between the two commonly associated toxic metals of chromate, Cr(VI), and arsenite, As(III), with regards to the ability of As(III) to reductively activate Cr(VI) to generate oxidative stress and DNA damage. Using a DCF-based fluorescent dye assay we have demonstrated that the redox reaction between As(III) and Cr(VI) yields high valent intermediates of chromium, Cr(V), that are highly oxidizing. This induction of oxidizing potential was dose dependent and did not occur with As(III) or Cr(VI) alone or, with the other major oxidation state of arsenic, arsenate, As(V). The mechanism of oxidation of DCFH to the fluorescent species, DCF, in this reaction was through a direct, metal-based oxidation since addition of radical scavengers did not significantly decrease oxidation of the dye in this system. The addition of a ligand that stabilizes the high valent Cr(V) oxidation state, 2-ethyl-2-hydroxybutyric acid (EHBA), to the chromate and arsenite mixture resulted in an enhancement of DCF fluorescence. The DCF fluorescence observed with the Cr(VI) and As(III) mixture was also found to correlate with oxidative DNA damage as measured by a plasmid nicking assay. These data show how metal–metal interactions in environmental mixtures could result in the synergistic induction of oxidative stress and DNA damage. Further, these data demonstrate the utility of the DCF fluorescence assay as a sensitive method for screening synergistic redox interactions in metal mixtures.