Photo-induced DNA damage and photocytotoxicity of retinyl palmitate and its photodecomposition products

Retinyl palmitate (RP) is an ester of retinol (vitamin A) and the predominant form of retinol found endogenously in the skin. We have previously reported that photoirradiation of RP with UVA light resulted in the formation of anhydroretinol (AR), 5,6-epoxyretinyl palmitate (5,6-epoxy-RP) and other photodecomposition products. While AR was formed through an ionic photodissociation mechanism, 5,6-epoxy-RP was formed through a light-mediated, free radical-initiated chain reaction. In the current study, the phototoxicity of RP, AR and 5,6-epoxy-RP in human skin Jurkat T-cells with and without light irradiation was determined using a fluorescein diacetate assay. Under similar conditions, the Comet assay was used to assess damage to cellular DNA. Nuclear DNA was not significantly damaged when the cells were irradiated by UVA plus visible light in the absence of a retinoid; however, when the cells were illuminated with UVA plus visible light in the presence of either RP, 5,6-epoxy-RP or AR (50, 100, 150 and 200 microM), DNA fragmentation was observed. Cell death was observed for retinoid concentrations of 100 microM or higher. When treated with 150 microM of RP, 5,6-epoxy-RP or AR, cell death was 52, 33 and 52%, respectively. These results suggest that RP and its two photodecomposition products, AR and 5,6-epoxy-RP, induce DNA damage and cytotoxicity when irradiated with UVA plus visible light. We also determined that photoirradiation of RP, AR and 5,6-epoxy-RP causes single strand breaks in supercoiled phi chi 174 plasmid DNA. Using a constant dose of UVA light (50 J/cm2), the level of DNA cleavage was highest in the presence of AR, followed by 5,6-epoxy-RP, then RP. The induced DNA strand cleavage was inhibited by NaN3. These results suggest that photoirradiation of RP, 5,6-epoxy-RP and AR with UVA light generates free radicals that initiate DNA strand cleavage.     

紫外线诱导HaCaT细胞IL10 mRNA及蛋白表达

目的探讨紫外线致机体免疫抑制的作用机制。方法体外培养人角质形成细胞系（HaCaT）,以0.6,1.2,1.8,2.4,3.0,3.6 J/cm^2长波紫外线（UVA）照射,采用四甲基偶氮噻唑蓝（MTT）法检测细胞活力。以2.4 J/cm^2UVA照射HaCaT细胞,于0,2,4,12,24,48 h收集细胞及培养掖,分别采用RT-PCR和双抗夹心ELISA方法,检测白细胞介素10（IL10）mRNA及其蛋白表达。结果3.0,3.6 J/cm^2UVA照射使体外培养的HaCaT细胞活力明显降低（P〈0.05）;0.6～2.4 J/cm^2UVA照射对细胞活力无明显影响（P〉0.05）。HaCaT细胞经2.4J/cm^2UVA照射后12h,IL19 mRNA呈弱表达;照射后24h,培养液中IL10蛋白水平为（17.45±0.65）pg/ml;照射组其他各检测时点及对照组细胞未见IL10 mRNA及蛋白表达。结论正常情况下HaCaT细胞并不表达IL10,UVA照射可诱导其表达。     

HSF1/HSP70通路抑制c-Jun氨基末端激酶的活化保护UVA诱导的HaCaT细胞凋亡

目的观察热休克转录因子1(HSF1)与热休克蛋白70(HSP70)对紫外线A(UVA)诱导HaCaT细胞凋亡的保护作用及其机制。方法建立8mJ/cm2UVA辐射损伤HaCaT细胞的病理模型。将细胞随机分为对照组、8mJ/cm2UVA照射组、HSP70转录抑制剂组(50μmol/L槲皮素)。Honechst 33258荧光染色观察细胞凋亡;蛋白质印迹法检测UVA辐射HaCaT细胞后p-HSF1和HSP70蛋白的经时变化及UVA辐射后孵育6h JNK(c-Jun氨基末端激酶)、p-JNK的蛋白表达;Real-Time PCR检测HSP70 mRNA的表达。结果 UVA辐射后HaCaT细胞内p-HSF1、HSP70蛋白表达量均出现先增加后减少的时间依赖性趋势,其中p-HSF1于1h开始增加,3h达高峰,HSP70于6h达高峰,24h基本恢复原始水平;UVA辐射前预先加入HSP70转录抑制剂槲皮素能显著抑制HSP70 mRNA的表达,增加p-JNK的表达量,同时Honechst 33258荧光染色观察其与UVA辐射组比较凋亡率明显升高。结论 8mJ/cm2UVA辐射HaCaT细胞在一定时间内可使HSF1活化致HSP70表达增加。HSF1/HSP70通路对UVA诱导的HaCaT细胞凋亡具有保护作用,其机制与HSP70大量表达后抑制JNK的活化有关。     

丙烯酰胺对人角质形成细胞DNA损伤的研究

目的　研究丙烯酰胺 (AA)对人角质形成细胞的细胞毒性和对DNA的损伤及其可能机制。方法　 (1 )人角质形成细胞株HaCaT细胞经AA浓度梯度染毒 44h后 ,以四氮唑盐 (MTT)法检测细胞存活率。 (2 )细胞经AA浓度梯度染毒 ,以彗星试验检测细胞DNA损伤。 (3)细胞经 2 .0 0mmol/LAA和 0 .50mmol/L的细胞色素P 450 (CYP 450 )抑制剂 1 ABT共处理 4h后 ,以彗星试验探索DNA损伤与CYP 450的关系。结果　 (1 )细胞毒性试验显示 ,AA染毒 44h后细胞存活率显著下降。 (2 )AA染毒 4h未观察到细胞毒性 ,但各组细胞的DNA较对照组均检测到显著损伤 ,且损伤程度随染毒剂量增大而加重 ,彗尾长度在处理剂量范围内有明显的剂量效应关系 ;细胞经 1 ABT和 2 .0 0mmol/LAA共同处理后 ,拖尾率和尾长为 1 5 .4 %和 (8.2± 2 .0 ) μm ,较 2 .0 0mmol/LAA组 [80 .6 %和 (44.3± 4 .0 ) μm]明显降低 ,差异有显著性 (P <0 .0 1 )。结论　AA对HaCaT细胞具有细胞毒性和基因毒性 ,AA诱导的DNA损伤可能与其经CYP 450作用产生的氧化代谢物有关     

扇贝多肽对紫外线A诱导HaCaT细胞Fas、c-fos表达的影响

目的观察扇贝多肽(PCF)对紫外线A(UVA)照射后HaCaT角质形成细胞Fas、c-fos表达的影响,以探讨PCF保护UVA致HaCaT细胞损伤的分子机制。方法体外培养的HaCaT角质形成细胞分为5组:对照组、UVA模型组、5.69mmol/LPCF组、2.84mmol/LPCF组、1.42mmol/LPCF组。蛋白质印迹法检测Fas、c-fos蛋白表达;RT-PCR检测FasmRNA表达;荧光定量PCR检测c-fosmRNA表达。结果 UVA照射后模型组Fas、c-fos表达均显著增加(P0.01),1.42～5.69mmol/L剂量范围内的PCF可抑制UVA引起的HaCaT细胞Fas、c-fosmRNA及蛋白表达(P0.05),且有剂量依赖性。结论 PCF可通过抑制Fas、c-fos表达而抑制UVA诱导的HaCaT细胞损伤。     

氧化乐果对小鼠精子DNA损伤的研究

目的 研究有机磷农药氧化乐果对雄性小鼠精子DNA的损伤作用.方法 将18～20 g清洁级昆明种雄性小鼠按体重随机分为氧化乐果低(0.5 mg/kg)、中(1 mg/kg)、高(2 mg/kg)剂量组和对照组(等体积生理盐水),每组10只.每天灌胃染毒1次,连续35 d.染毒后,称量体重,取出睾丸和附睾、称重,计算睾丸系数.采用彗星试验检测小鼠精子DNA的损伤情况,采用Nikon荧光显微镜和图像采集卡进行拍照,用MIM软件对所拍摄的图像进行分析,以评估精子细胞DNA受损伤程度.结果 随着氧化乐果染毒剂量的增加,小鼠体重、睾丸重量以及睾丸系数均呈下降趋势,但差异均无统计学意义(P＞0.05);良好精子的构成比和精子密度呈下降趋势,死亡精子的构成比和精子畸形率呈上升趋势;彗星长度、彗星重心、尾长、尾重心、Olive尾矩、尾惯量、尾长/头长、尾部DNA含量均呈上升趋势.精子畸形主要以胖头和尾折叠为主.结论 氧化乐果对小鼠精子DNA有明显的损伤作用.     

Lycopene enhances UVA–induced DNA damage and expression of heme oxygenase–1 in cultured mouse embryo fibroblasts

Summary Background It has been suggested that carotenoids including lycopene may reduce the risk of photodamage. However, carotenoids are unstable under light exposure and may produce prooxidative effects under certain circumstances. Aim of the study We examined whether lycopene inhibits ultraviolet A (UVA)–induced DNA damage and the expression of heme oxygenase–1 (HO–1). We hypothesized that the breakdown of lycopene by UVA irradiation, rather than intact lycopene itself, causes oxidative damage. Methods Mouse fibroblasts, C3H10T1/2 (C3H), were first enriched with 10 µM of lycopene in the dark for 2 h before exposure to UVA (22.5 KJ/m²). Then, DNA damage measured by the single–cell gel electrophoretic assay (comet assay) and the expression of HO–1 measured by western blotting were determined. In addition, we exposed lycopene powder to UVA (22.5 KJ/m²) to prepare pre–irradiated lycopene (ILP). Then, C3H cells were incubated with ILP for 2 h, and DNA damage and the expression of HO–1 also were determined. Results We found that lycopene enrichment did not cause damage to DNA in C3H cells not irradiated with UVA. However, lycopene enrichment strongly induced DNA damage when cells were irradiated with UVA (by ca. 2–fold as compared to control). In addition, lycopene enhanced UVA–induced HO–1 expression by ca. 2.5–fold. UVA irradiation led to a significant loss of lycopene that had been pre–incorporated into C3H cells. When cells were incubated with lycopene that had been pre–irradiated with UVA without subjecting the cells to further UVA irradiation, cellular DNA damage and expression of HO–1 were markedly increased, and these effects of irradiated lycopene were concentration–dependent. Conclusions These results demonstrate that lycopene enhances UVA–induced oxidative stress in C3H cells, and they suggest that under UVA irradiation, lycopene may produce oxidative products that are responsible for the prooxidant effects.     

Genotoxicity of acute and chronic gamma-irradiation on zebrafish cells and consequences for embryo development

The effects of radiation on biological systems have been studied for many years, and it is now accepted that direct damage to DNA from radiation is the triggering event leading to biological effects. In the present study, DNA damage induced by acute or chronic irradiation was compared at the cellular (zebrafish [Danio rerio] cell line ZF4) and developmental (embryo) levels. Zebrafish ZF4 cells and embryos (at 3 h postfertilization) were exposed within ranges of acute doses (0.3-2 Gy/d) or chronic dose rates (0.1-0.75 Gy/d). DNA damage was assessed by immunodetection of γ-H2AX and DNA-PK (DNA double-strand breaks) and the alkaline comet assay (DNA single-strand breaks). Zebrafish embryo development and DNA damage were examined after 120 h. At low doses, chronic irradiation induced more residual DNA damage than acute irradiation, but embryo development was normal. From 0.3 Gy, a hyper-radiosensitivity phenomenon compared to other species was shown for acute exposure with an increase of DNA damage, an impairment of hatching success, and larvae abnormalities. These results suggest a dose-dependent correlation between unrepaired DNA damage and abnormalities in embryo development, supporting the use of DNA repair proteins as predictive biomarkers of ionizing radiation exposure. This could have important implications for environmental protection.     

Sequence-specific DNA damage by reactive oxygen species: Implications for carcinogenesis and aging

Reactive oxygen species (ROS) generated by environmental chemicals can cause sequence-specific DNA damage, which may lead to carcinogenesis and aging. We investigated the mechanism of DNA damage by environmental chemicals (catechol, propyl gallate and bisphenol-A), homocysteine and UVA radiation using human cultured cell lines and³²P-labeled DNA fragments. Carcinogenic catechol induced piperidine-labile sites frequently at thymine residues in the presence of Cu(II) and NADH. Furthermore, catechol increased the formation of 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG), a characteristic oxidative DNA lesion, in human leukemia cell line HL-60, but not in HP100, a hydrogen peroxide (H₂O₂)-resistant cell line derived from HL-60. Thus, it is concluded that oxidative DNA damage through generation of H₂O₂ plays an important role in the carcinogenic process of catechol. In addition, an environmental factor, bisphenol-A, and a dietary factor, propyl, gallate, also induced sequence-specific DNA damage via ROS generation. UVA, as well as UVB, contributes to photoaging. In humans, telomere shortening is believed to be associated with cell senescence. In this study, we investigated the shortening rate of telomeres in human WI-38 fibroblasts exposed to UVA irradiation. The telomere length (as measured by terminal restriction fragment length) in WI-38 fibroblasts irradiated with UVA decreased with increasing the irradiation dose. UVA irradiation with riboflavin caused damage specifically at the GGG sequence in the DNA fragments containing telomere sequence (TTAGGG)₄. We concluded that the GGG-specific damage in telomere sequence induced by UVA irradiation participates in the increase of the telomere shortening rate. In this report, we show our experimental results and discuss the mechanisms of sequence-specific DNA damage in relation to carcinogenesis and aging. This article is based upon the research that was given Encouragement Award at the 74th Annual Meeting of the Japanese Society for Hygiene held in Tokyo, Japan on March 24–27, 2004.     

Protection by the flavonoids myricetin, quercetin, and rutin against hydrogen peroxide-induced DNA damage in Caco-2 and Hep G2 cells

Flavonoids are reported to exhibit a wide variety of biological effects, including antioxidant and free radical-scavenging activities. Reactive oxygen species have been implicated in a range of human pathological diseases such as atherosclerosis and certain cancers. The aims of this present study were 1) to investigate the effect of the flavonoids myricetin, quercetin, and rutin on cell viability, endogenous antioxidant enzyme activities, and DNA integrity in Caco-2 and Hep G2 cells and 2) to determine whether these flavonoids could protect against H2O2-induced DNA damage. Both cell lines were supplemented with various concentrations (0-200 microM) of myricetin, quercetin, and rutin for 24 hours or H2O2 (50 microM) for 30 minutes, and cell viability was assessed. Over the concentration range tested, neither the flavonoids nor H2O2 significantly affected cell viability. The effect of the flavonoids on the activities of the antioxidant enzymes catalase (EC 1.11.1.6) and superoxide dismutase (EC 1.15.1.1) and on DNA integrity was assessed. The flavonoids did not significantly affect catalase or superoxide dismutase activity and did not induce DNA damage in either cell line. Exposure to 50 microM H2O2 for 30 minutes at 37 degrees C resulted in significant DNA damage, and preincubation with the flavonoids before H2O2 exposure significantly (p < 0.05) protected Caco-2 and Hep G2 cells against H2O2-induced DNA damage.     

镉致DNA损伤及对原癌基因蛋白表达的影响

目的 研究氯化镉致人细胞和整体动物DNA损伤作用和对原癌基因等相关蛋白表达的影响.方法 雄性Wistar大鼠,体重约150 g,按每组8只分为1个对照组和2个染毒剂量组,以生理盐水配制氯化镉溶液经皮下注射进行染毒,剂量分别为5和20 μmol/kg,对照组注射生理盐水.用集落形成实验和四唑盐比色法（MTT）测定氯化镉的细胞毒性,用彗星实验检测氯化镉对DNA的损伤,采用流式细胞术测定细胞周期的变化,用免疫印迹和X-Gal染色检测相关蛋白的表达改变.结果 镉能明显抑制细胞增殖,对人成纤维和整体动物细胞DNA有明显的损伤作用,成纤维细胞彗星细胞率由对照组的6.1%增加到200μM剂量组的23.2%,差异有统计学意义（P＜0.01）.雄性大鼠各个脏器在镉染毒后彗星细胞的频率均随剂量的增高而增加,其中肾和腹侧前列腺的DNA损伤同对照组比较差异有统计学意义（P＜0.05）,镉能进一步引起细胞周期阻滞.原癌基因c-myc、c-Jun和老化标记蛋白β-Gal均被氯化镉诱导增加.结论 氯化镉能致DNA损伤并进一步引起细胞周期停滞,导致细胞老化、死亡.氯化镉诱导细胞的DNA损伤和原癌基因表达的增加也可能是镉致癌的重要原因.     

Kidney Cell DNA Damage Caused By Combined Exposure To Volatile Anaesthetics and 1 Gy Or 2 Gy Radiotherapy Dose in Vivo

Patient immobilisation with volatile anaesthetics (VA) during radiotherapy is sometimes unavoidable. Although it is known that both VAs and ionising radiation can have nephrotoxic effects, there are no studies of their combined effects on DNA damage. The aim of this in vivo study was to address this gap by investigating whether 48 groups of healthy Swiss albino mice (totalling 240) would differ in kidney cell DNA damage response (alkaline comet assay) to isoflurane, sevoflurane, or halothane anaesthesia and exposure to 1 Gy or 2 Gy of ionising radiation. We took kidney cortex samples after 0, 2, 6, and 24 h of exposure and measured comet parameters: tail length and tail intensity. To quantify the efficiency of the cells to repair and re-join DNA strand breaks, we also calculated cellular DNA repair index. Exposure to either VA alone increased DNA damage, which was similar between sevoflurane and isoflurane, and the highest with halothane. In combined exposure (VA and irradiation with 1 Gy) DNA damage remained at similar levels for all time points or was even lower than damage caused by radiation alone. Halothane again demonstrated the highest damage. In combined exposure with irradiation of 2 Gy sevoflurane significantly elevated tail intensity over the first three time points, which decreased and was even lower on hour 24 than in samples exposed to the corresponding radiation dose alone. This study confirmed that volatile anaesthetics are capable of damaging DNA, while combined VA and 1 Gy or 2 Gy treatment did not have a synergistic damaging effect on DNA. Further studies on the mechanisms of action are needed to determine the extent of damage in kidney cells after longer periods of observation and how efficiently the cells can recover from exposure to single and multiple doses of volatile anaesthetics and radiotherapy.Key words: DNA repair index, comet assay, halothane, isoflurane, sevoflurane, tail intensity, tail length     

Yellow Gentian Root Extract Provokes Concentration- and Time-dependent Response in Peripheral Blood Mononuclear Cells

Yellow gentian (Gentiana lutea L.), a medicinal plant widely used in traditional medicine, displays multiple biological effects, ranging from beneficial to toxic. Since many promising applications have been reported so far, our aim was to evaluate its potential concentration- and time- dependent cytotoxic and genotoxic effects in vitro. To that end we exposed human peripheral blood mononuclear cells to 0.5, 1, and 2 mg/mL of yellow gentian root extract (YGRE) to determine its effects on oxidative stress parameters [pro/antioxidant balance (PAB) and lipid peroxidation], DNA damage (alkaline comet assay and chromosome aberrations), and cell viability (trypan blue exclusion test). Cell viability decreased with increasing concentrations and treatment duration. Only the lowest YGRE concentration (0.5 mg/mL) increased oxidative stress but produced minor DNA damage and cytotoxicity. At higher concentrations, redox parameters returned to near control values. The percentage of chromosome aberrations and percentage of DNA in the comet tail increased with increased YGRE concentration after 48 h and declined after 72 h of treatment. This points to the activation of DNA repair mechanism (homologous recombination), evidenced by the formation of chromosomal radial figures after 72 h of treatment with the highest YGRE concentration of 2 mg/mL. Our results suggest that YGRE, despite induction of cytotoxic and genotoxic effects, activates cell repair mechanisms that counter oxidative and DNA lesions and induce cell death in highly damaged cells. Therefore, observed protective effects of yellow gentian after longer exposure could be a result of activated repair and removal of cells with irreparable damage.Key words: cytotoxicity, genotoxicity, Gentiana lutea L., homologous recombination, redox parameters     

卷烟烟气致人淋巴细胞细胞毒性和遗传毒性的体外试验

目的 用不同体外试验评价卷烟烟气粒相物提取液(CSCs)致人外周血淋巴细胞的细胞毒性和遗传毒性.方法 分别以25、50、75、100和125 ug/ml的CSCs在加或不加肝脏微粒体酶(S9)系统下作用于人外周血淋巴细胞3 h,然后用CCK-8试验检测细胞毒性,用彗星试验检测DNA损伤,用hprt和TCR基因突变试验检测体细胞突变;以75ug/ml的CSCs作用于人外周血淋巴细胞3 h,分别给予30、60、90、120和240 min的修复时间,然后用彗星试验评价淋巴细胞的DNA修复情况.结果 细胞活性随剂量增加明显降低,100、125 ug/ml CSCs加S9组细胞活性明显高于不加S9组,差异有统计学意义(P<0.05,P<0.01);随CSCs暴露剂量增加,DNA损伤明显增加,并明显高于对照组,差异有统计学意义(P<0.01);各剂量加S9组DNA损伤明显低于不加S9组,差异有统计学意义(P<0.05,P<0.01).各剂量组TCR基因突变率明显高于对照组,差异有统计学意义(P<0.05,P<0.01).中高剂量组hprt基因突变率明显高于对照,差异有统计学意义(P<0.01),中、高剂量加S9与不加S9两组间TCR和hprt基因突变率均存在明显差异,差异有统计学意义(P<0.05,P<0.01).加与不加S9两组DNA损伤均可基本修复至正常水平,但两者修复速度存在差异.结论 CSCs可在体外诱发人外周血淋巴细胞的细胞和遗传损伤,但S9可降低CSCs毒性的效应,并可影响人淋巴细胞DNA损伤的修复速率.     

DHEA对辐射所致小鼠DNA损伤防护作用的研究

目的 探讨DHEA(17 a α-D-高炔雌二醇-3-乙酯)对辐射导致小鼠DNA损伤的防护作用。方法 IRM-2近交系小鼠照射前3 d、2 d、1 d连续3次给予DHEA,用单细胞凝胶电泳技术,检测2 Gy γ射线辐照后小鼠淋巴细胞DNA双链断裂。结果 DHEA低、中、高各剂量组、炔雌醇组(EE2)、尼尔雌醇组(523)的彗星尾部(TDNA%)、彗星尾长(TL)、尾矩(TM)和Olive尾矩(OTM)等指标的数值明显低于对照组,与对照组比较差异有统计学意义(P < 0.01),DHEA中剂量组的TDNA、TL、TM和OTM等指标的数值明显低于EE2组和523组,与EE2组和523组比较差异有统计学意义(P < 0.01)。结论 DHEA能明显减轻淋巴细胞DNA双链断裂损伤,对辐射导致小鼠DNA损伤具有明显的保护作用。     

Genotoxicity induced by pesticide mixtures: in-vitro studies on human peripheral blood lymphocytes

To assess the damage caused by pesticides and their mixtures on humans, we designed in-vitro experiments to evaluate their cytotoxicity and genotoxicity. Three equimolar pesticide mixtures were investigated for their capability to affect cultured human peripheral blood lymphocytes. The LC50 values for cytotoxicity, using standard trypan blue dye exclusion and calculated by probit analysis, were 4.18, 5.76, and 7.5 microM for endosulfan, carbofuran, and monocrotophos, respectively. When combined in equimolar concentrations, the LC50 values for cytotoxicity were 0.7, 0.9, and 1.0 microM for monocrotophos + carbofuran, endosulfan + monocrotophos, and endosulfan + carbofuran, respectively, using the method. DNA damage was estimated using chromosomal aberrations (chromatid breaks, fragments, gaps, aneuploidy, and satellite association) and comet assays using 1/10 of the LC50 concentrations. Using a standard alkaline comet assay procedure, high concentrations of individual pesticides (0.5-4.0 microM) caused significant DNA damage as indicated by visible tail lengths. Lower concentrations (0.05-0.5 microM) of their binary mixtures could cause the same effect. The results suggest that analysis of genotoxicity may serve as an important biomarker for occupational and household exposure to pesticides, especially mixtures of pesticides, with different modes of action.     

构树总黄酮对长波紫外线引起人角质形成细胞损伤的防护作用

目的研究长波紫外线(UVA)照射对人角质形成细胞的氧化损伤以及构树总黄酮(totalflavonoids of broussonetia papyrifera,TFBP)的防护效果。方法在人角质形成细胞培养的基础上,实验组在照射前加入不同剂量的TFBP,然后和处理组一起接受UVA照射,通过噻唑蓝(MTT)染色法检测细胞活性、裂解液中丙二醛(MDA)含量和超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)活力,对构树叶提取物的抗氧化效果进行评价。结果随着UVA剂量的增高(0.46~2.76J/cm2),细胞的活性逐渐降低(96.3%~37.5%),添加TFBP10~200mg/L后,细胞活性升高,MDA含量由(5.14±0.58)nmol/mg pro降低到(2.98±0.14)nmol/mg pro,SOD活力由(23.09±3.91)U/mg pro增加到(34.50±1.59)U/mg pro,GSH-Px活力也有所升高。结论本试验条件下,UVA对人角质形成细胞有明显的氧化损伤,TFBP对这种氧化损伤有防护作用。     

2 450 MHz微波对三种诱变剂致DNA损伤作用的影响

目的　研究 2 4 5 0MHz(5mW cm2 )微波 (MW)与 3种化学诱变剂对人淋巴细胞DNA损伤的联合作用。方法　采用彗星试验体外实验检测淋巴细胞经微波和化学诱变剂单独及联合作用后 ,不同培养时间 (0h和 2 1h)的DNA损伤。微波与化学诱变剂联合暴露方式有 3种 :微波辐射后化学诱变剂染毒、微波与化学诱变剂同时暴露、化学诱变剂染毒后微波辐射。 3种化学诱变剂是丝裂霉素C(MMC ,DNA交联剂 )、博来霉素 (BLM ,似X线剂 )、甲基甲烷磺酸酯 (MMS ,烷化剂 )。微波辐射和化学诱变剂暴露时间分别是 2h和 3h。结果　微波组培养 0h和 2 1h ,彗星尾长与对照组比较 ,差异无显著性 (P >0 .0 5 )。培养 2 1h后 ,当MMC浓度为 30 .0 0 μmol L时 ,MW +MMC组、MW MMC组和MMC +MW组的尾长分别为 (18.0 0± 5 .96 )、(2 1.79± 11.4 7)、(2 2 .32± 8.10 ) μm ;当MMC浓度为 3.0 0μmol L时 ,尾长分别为 (8.99± 3.75 )、(12 .4 0± 5 .35 )、(14 .0 0± 5 .38) μm ,明显高于相应的MMC组[(9.4 2± 3.34) μm和 (6 .5 0± 2 .89) μm],差异有显著性 (P <0 .0 1或P <0 .0 5 )。MW +BLM组和MW +MMS组的DNA损伤与相应的BLM组和MMS组比较 ,差异无显著性 (P >0 .0 5 )。结论　 2 4 5 0MHz(5mW cm2 )微波辐射 2h未观察到明显的人淋巴细胞     

手机模拟电磁信号对人眼晶状体上皮细胞DNA损伤及修复的影响

目的 检测手机微波辐照2 h后人眼晶状体上皮细胞（human lens epithelial cells,LECs）的DNA损伤及其修复情况.方法 LECs分为辐照组和假辐照组,置于sXc-1800细胞辐照（发射217 Hz脉冲调制的1.8 GHz微波）系统内连续波辐照2 h,辐照强度比吸收率（specific absorption rate,SAR）分别为0、1、2、3、4W/kg,辐照后0、30、60、120、240min分别进行彗星试验检测尾长和尾相,以判定细胞DNA的损伤及其修复情况.结果 1和2 W/kg辐照诱导的DNA损伤与假辐照组相比,在各个检测时段的差异均无统计学意义（P＞0.05）;辐照后即刻进行的检测发现,3和4W/kg组DNA损伤与假辐照组相比,差异有统计学意义（P＜0.01）,3 W/kg组的差异在修复30 min后仍然存在,修复60min后消失,而4 W/kg组的差异在各检测时段持续存在.结论 SAR≤3 W/kg的1.8 GHz手机微波辐照2 h对体外培养的人眼晶状体上皮细胞不产生或产生可修复DNA损伤,4 W/kg的辐照剂量可导致细胞DNA不可逆性损伤.     

低功率微波致雄性小鼠生殖细胞DNA损伤作用

目的探讨低功率微波对小鼠雄性生殖细胞DNA的损伤作用。方法选择清洁级昆明种雄性小鼠40只,随机分为1个对照组和3个辐照组,每组10只。微波辐射源平均功密度为250μW/cm2,频率为900 MHz的连续波,全身24 h暴露。分别于照射后5,10,15 d处死小鼠,观察小鼠睾丸细胞拖尾率、尾长、尾部DNA%和Olive尾矩(OTM)等。结果微波辐射连续照射使小鼠睾丸细胞拖尾率、尾长、尾部DNA%和OTM明显升高,照射后15 d拖尾率达45.8%,尾长、尾部DNA%和Olive尾矩分别为(33.81±16.87)μm,(33.92±20.32)%和(11.08±8.54),与对照组比较差异均有统计学意义(P0.01)。结论连续微波辐射对雄性小鼠生殖细胞DNA有损伤作用,具有时间效应关系。