Effects of gamma rays on the regeneration of murine hair follicles in the natural hair cycle

Purpose: This review evaluates the effects of γ-rays on the regeneration of murine hair follicles in the natural hair cycle. A series of studies were performed to investigate this issue, in which the whole bodies of C57BL/10JHir mice in the 1st telogen phase of the hair cycle were irradiated with γ-rays.

Results: The dermis of the irradiated skin showed a decrease in hair follicle density and induction of curved hair follicles along with the presence of white hairs and hypopigmented hair bulbs in the 2nd and 3rd anagen phases. An increased frequency of hypopigmented hair bulbs was still observed in the later hair cycle at postnatal day 200. There was no significant difference in the number of stem cells in the hair bulge region between control and irradiated skin.

Conclusions: These results show that the effects of γ-rays on the pigmentation of murine hair follicles are persistently carried over to later hair cycles, although those on the number and structure of hair follicles appear to be hidden by the effects of aging. Our findings may be important for understanding the mechanisms of the actions of stem cells on hair regeneration in connection with age-related phenotypes.     

X射线和γ射线预处理对小鼠异基因骨髓移植后造血免疫重建的影响

目的 研究X射线和γ射线两种预处理方式造成的损伤程度的差别,以及对造血、免疫重建的影响,确定适用于异基因造血干细胞移植的预处理照射方式.方法 对受鼠分别使用直线加速器X射线或60Coγ射线进行致死剂量(总剂量为7.0 Gy)全身照射后,给予相同数量供鼠骨髓细胞移植.观察受鼠移植后的生存时间、重要脏器(肝、小肠和肺)病理...     

毛囊Bulge细胞的分离培养及生物学特性研究

目的分离培养大鼠毛囊Bulge细胞并观察其生物学特性。方法运用显微分离法及酶消化法分离大鼠毛囊Bulge细胞并进行培养,观察其增殖能力及细胞形态等的改变;采用免疫组化方法,检测毛囊Bulge细胞K19、岛整合素的表达情况。结果本方法培养的大鼠毛囊Bulge细胞纯度高、活力好,具有高增殖、低分化特性,同时表达K19、岛整合素。结论成功地分离培养了毛囊Bulge细胞,并在体外长期保持其低分化特性,为进一步深入研究毛囊发育分化提供了实验基础。     

Effect of Heat on Radiosensitivity at Different Developmental Stages of Embryos of the Fish Oryzias Latipes

Summary

Embryos of the fish, Oryzias latipes, at various developmental stages were heated before or after γ-irradiation. The lethal effects of heat and radiation treatments were determined by the hatchability of the irradiated embryos. The radiosensitivity suddenly decreased at 3-days after fertilization. Heat (41°C), either preceding or following irradiation, decreased the shoulder region (D_q) of the dose-response curves of the embryos irradiated at the 1–3 day stages, and increased the slope (D₀) only at the 3 day stage. The magnitude of enhancement of radiosensitivity by pre- and post-heating was found to depend on the time and temperature of the heat as well as the developmental stage of the embryos; in 1-and 2-day embryos the effectiveness of post-irradiation heating was larger than that of pre-irradiation heating whereas in 3-day embryos there was no difference between the effectiveness of pre- and post-treatment. The sequence of heat (41°C) and radiation treatment, and the time interval between the two treatments, also influenced the effectiveness of heat on radiosensitivity, depending upon the developmental stage; recovery from heat effects was not observed within a time interval of up to 3 h before radiation exposure for either 1- or 3-day embryos, whereas recovery from the radiation lesion occurred, for only 1-day embryos, within 1 h of subsequent heat exposure.     

小剂量γ射线全身照射对小鼠脑组织氨基酸类神经递质含量的影响

目的 探讨小剂量γ射线全身照射后对小鼠中枢神经系统的影响.方法 将50只C57小鼠按随机表法分为健康对照组及0.5和1 Gy照射组.用60Co γ射线全身照射,吸收剂量为0.5和1 Gy,吸收剂量率为19.2 cGy/min,连续照射3d,1次/d,照射后24和48 h取小鼠脑组织并匀浆,用高效液相色谱荧光法(HPLC)测定匀浆上清中氨基酸类神经递质(谷氨酸、天冬氨酸、γ-氨基丁酸及甘氨酸)含量.结果 与健康对照组相比,0.5Gyγ射线照射后48 h以及1 Gy照射后24和48 h,小鼠脑内谷氨酸和天冬氨酸含量表达增高(t=- 4.080、- 3.935、-4.416、- 3.630、-4.831和- 4.656,P＜0.05);而0.5Gyγ射线照射后24 h小鼠脑内谷氨酸、天冬氨酸含量无明显改变.各照射组小鼠脑内γ-氨基丁酸和甘氨酸含量与健康对照组比较,差异无统计学意义.结论 小剂量γ射线短期全身照射对小鼠中枢神经系统具有轻度的兴奋作用.     

Biological outcomes of γ-radiation induced DNA damages in breast and lung cancer cells pretreated with free radical scavengers

Abstract

Purpose: Investigation of effects on DNA of γ-irradiated human cancer cells pretreated with free radical scavengers is aimed to create reference data which would enable assessment of the relative efficiency of high linear energy transfer (LET) radiations used in hadron therapy, i.e. protons and carbon ions.

Materials and methods: MCF-7 breast and HTB177 lung cancer cells are irradiated with γ-rays. To minimize indirect effects of irradiation, dimethyl sulfoxide (DMSO) or glycerol are applied as free radical scavengers. Biological response to irradiation is evaluated through clonogenic cell survival, immunocytochemical and cell cycle analysis, as well as expression of proteins involved in DNA damage response.

Results: Examined cell lines reveal similar level of radioresistance. Application of scavengers leads to the rise of cell survival and decreases the number of DNA double strand breaks in irradiated cells. Differences in cell cycle and protein expression between the two cell lines are probably caused by different DNA damage repair mechanisms that are activated.

Conclusion: The obtained results show that DMSO and glycerol have good scavenging capacity, and may be used to minimize DNA damage induced by free radicals. Therefore, they will be used as the reference for comparison with high LET irradiations, as well as good experimental data suitable for validation of numerical simulations.     

mBAND analysis of chromosome aberrations in lymphocytes exposed in vitro to α-particles and γ-rays

Purpose:?To investigate the profiles of chromosome damage induced in vitro by exposure to α-particles and γ-rays.

Materials and methods:?Human peripheral blood lymphocytes were exposed to three dose regimes: α-particle doses of 0.2 and 0.5 Gy and a γ-ray dose of 1.5 Gy. After culturing for 47 hours, chromosome aberrations involving the number 5 chromosomes were identified using a multi-coloured banding (mBAND) technique.

Results:?Analysis of the frequencies of chromosome 5 breaks within aberrant cells and within aberrant number 5 chromosomes demonstrated that α-particle irradiation is more likely to result in multiple breaks in a chromosome than γ-irradiation. Additionally, overdispersion was observed for all doses for the distribution of breaks amongst all cells analysed and breaks amongst total number 5 chromosomes, with this being greatest for the 0.2 Gy α-particle dose. The ratio of interchanges to intrachanges (F ratio) was 1.4 and 2.4 for 0.2 and 0.5 Gy α-particles respectively and 5.5 for 1.5 Gy γ-rays. Evaluation of simple versus complex exchanges indicated ratios of 1.9 and 2.7 for 0.2 and 0.5 Gy α-particles respectively and 10.6 for 1.5 Gy γ-rays. The majority of the intrachanges involving chromosomes 5 induced by α-particle radiation were associated with more complex exchanges.

Conclusions:?This study has confirmed that exchanges induced by exposure to high linear energy transfer (LET) α-particle radiation comprise a greater proportion of intrachanges than those induced by exposure to low LET γ-rays. However, since the majority of these are associated with complex rearrangements and likely to be non-transmissible, this limits their applicability as a marker of past in vivo exposure.     

γ射线诱发人外周血淋巴细胞T细胞受体基因突变剂量-效应和时间-效应关系

目的 初步建立T细胞受体(TCR)突变频率的剂量-效应和时间-效应模型,为探讨TCR作为估算辐射生物剂量计提供依据.方法 将10名健康成年人的外周血淋巴细胞分成两组.第1组4人(男性)的外周血淋巴细胞分别给予0、0.5、1.0、1.5、2.0、2.5、3.0、3.5、4.0和5.0 Gv γ射线照射,用于拟合剂量-效应曲线,第2组6人(男女各半)的外周血淋巴细胞给予2 Gy γ射线照射,用于拟合时间-效应曲线.用流式细胞仪进行计数检测,计算TCR基因突变频率.结果 γ射线照射诱发TCR MF的辐射剂量-效应曲线,拟合最佳的模型为二次方程模型:TCR MF=92.14+22·61D2(R2adj=0.65);γ射线照射诱发TCR MF的辐射时间-效应曲线,拟合最佳的模型为二次多项式方程模型:TCR MF=3.74+743.66T+308.64T2(R2adj=0.79).结论 0～5 Gy范围内TCR基因突变频率与辐射剂量存在剂量-效应关系.照后4 d内TCR基因突变频率随时间的延长而继续增加,存在时间-效应关系.

Abstract：

Objective To study the dose-effect relationship and time-effect relationship of T cell receptor (TCR) gene mutation induced by γ-rays in lymphocytes of human peripheral blood.Methods Samples of peripheral blood were collected from 10 healthy adults and lymphocytes were separated.Four samples from males used to fit time-effect curve were exposed to γ-rays at the doses of 0,0.5,1.0,1.5,2.0,2.5,3.0,3.5,4.0,and 5.0 Gy,respectively,and 6 samples from 3 males and 3 females used to fit dose-effect curves were exposed to γ-rays of the dose of 2 Gy.Flow cytometry was used to detect the mutation frequency of TCR gene (TCR MF).Radiation dose-effect curves and time-effect curves were fitted and optimal mathematical models were selected respectively.Results The optimal mathematical model for radiation dose-effect was quadratic equation model:TCR MF = 92.14 + 22.61D2 (R2adj = 0.65).The optimal mathematical model for radiation time-effect was quadratic polynomial equation model:TCR MF = 3.74 + 743.66T + 308.64T2 (R2adj = 0.79).Conclusions TCR MF is increased as the γ-rayirradiation dose increases within the range of 0-5 Gy,and TCR MF is increased with the lapse of time within the range of 4 days after γ-ray radiation.     

Optimized digital counting colonies of clonogenic assays using ImageJ software and customized macros: Comparison with manual counting

Abstract

Purpose: To develop a digital method for counting colonies that highly replicates manual counting.

Materials and methods: Breast cancer cells were treated with trastuzumab-conjugated gold nanoparticles in combination with X-ray irradiation, ¹¹¹In labeled trastuzumab, or γ-radiation, followed by clonogenic assays. Colonies were counted manually or digitally using ImageJ software with customized macros. Key parameters, intensity threshold and minimum colony size, were optimized based on three preliminary manual counts or blindly chosen. The correlation of digital and manual counting and inter- and intra-experimenter variability were examined by linear regression. Survival curves derived from digital and manual counts were compared by F-test (P < 0.05).

Results: Using optimized parameters, digital counts corresponded linearly to manual counts with slope (S) and R² value close to 1 and a small y-intercept (y₀): SK-BR-3 (S = 0.96 ± 0.02, R² = 0.969, y₀ = 5.9 ± 2.2), MCF-7/HER2-18 (S = 0.98 ± 0.03, R² = 0.952, y₀ = 0.74 ± 0.47), and MDA-MB-231 cells (S = 1.00 ± 0.02, R² = 0.995, y₀ = 3.3 ± 4.5). Both reproducibility and repeatability of digital counts were better than the manual method. Survival curves generated from digital and manual counts were not significantly different; P-values were 0.3646 for SK-BR-3 cells and 0.1818 for MCF-7/HER2-18 cells. Using blind parameters, survival curves generated by both methods showed some differences: P-values were 0.0897 for SK-BR-3 cells and 0.0024 for MCF-7/HER2-18 cells.

Conclusions: The colony counting using ImageJ and customized macros with optimized parameters was a reliable method for quantifying the number of colonies.     

氮氧自由基R-1对人肝细胞L-02的辐射防护作用

目的 探讨氮氧自由基R-1(简称R-1)对人肝细胞L-02的辐射防护作用.方法 在L-02细胞培养液中,加入终浓度为0、0.125、0.25、0.5、1、2、4、8、16、32μmol/L的R-1,作用24、48和72 h.用MTT法测定R-1的毒性作用,以筛选合适的R-1浓度.后续实验选择0.125、0.25、0.5、1 μmol/L 4个浓度组检测其防护作用.设终浓度4 mmol/L的细胞保护剂WR2721为阳性对照组.采用60Coγ射线照射,吸收剂量为0、1、2、4、8 Gy,照射72 h后,进行MTT比色法.L-02细胞分为2组:照射前30 min加药组和照射后立即加药组.终浓度均为0.25 μmol/L,吸收剂量为4 Gy,照射后72 h进行MTT比色实验.照射后10 d,用克隆形成实验检测不同浓度的R-1对L-02细胞活力的影响.选用防护效果最佳的0.25μmol/L浓度对细胞进行预处理,分别在4 Gy照射后的24、48和72 h,用倒置显微镜观察细胞形态的变化,Hoechst 33258荧光染色法和流式细胞仪检测细胞凋亡.结果 当R-1浓度低于1 μmoL/L时,与0 μmol/L组相比,L-02细胞各时间点的吸光度(A)值无明显变化;而浓度高于2 μmol/L时,与0 μmol/L组相比,其A值随浓度的增高而下降.选用0、0.125、0.25、0.5、1μmol/L的浓度组.与照射组相比,R-1各浓度组的A值和克隆形成率明显提高,其中0.25μmol/L组的作用最明显.与照射组相比,0.25 μmol/L预处理组的L-02细胞贴壁好,折光性强,轮廓清晰,凋亡细胞和死亡细胞明显较少.结论 R-1能有效地防护60Coγ射线对L-02细胞的辐射损伤,其防护作用可能与减少细胞凋亡有关.

Abstract：

Objcetive To investigate the protective effects of the nitroxides R-1 on human liver cells exposed to ionizing radiation.Methods Human liver cells L-02 were cultured and irradiated with 60Co γ-rays at the doses of 0,1,2,4,and 8 Gy,in order to screen the proper irradiation dose.WR2721 at the terminal concentration of 4 mmol/L was used as positive control.L-02 cells irradiated with 4 Gy were added with R-1 at the terminal concentration of 0.25 μmol/L at 30 min before irradiation or immediately after irradiation.MIT method was used to screen the proper conditions for follow-up experiment 72 h later.L-02 cell culture fluid was added with R-1 at the concentrations of 0,0.125,0.25,0.5,and 1 μmol/L,respectively for 30 min before irradiation at the doses of 0,1,2,4,and 8 Gy to ealculate clone formation rate at 10 d post-irradiation.L-02 cells were cultured and divided into 4 groups:control group without any treatment.drug group pretreated by 0.25 μmol/L R-1 only,irradiation group,irradiated at 4 Gy only,and drug + irradiation group with combination of 0.25 μmol/L R-01 and 4 Gy irradiation.The inverted microscopy and Hoechst 33258 staining and flow eytometry were used to observe the apoptosis of the cells at 24,48,and 72 h later.Results Nitroxides R-1 did not inhibit the viability of L-02 cell when its concentration was less than 1 μmol/L and it inhibited the L-02 cell growth when the concentration wu higher than 2 μmoL/L.The A value and colony formation rate of different concentration of R-1 groups were all higher than those of the irradiation group,and the effect of the 0.25 μmol/L drug concentration group was the most significant.Consequently,the concentration 0.25 μmoL/L was selected for follow-up experiment.Compared with the irradiation group,the L-02 cells of the pretreatment group showed solid adherence, increased refraction,clear outline,less apoptotic and dead cells at 4 Gy post-irradiation.Conclusions Nitroxides R-1 can protect the human liver cells from 60Coγ-ray induced injury effectively.The mechanism of its protective effect may be the reduction of apoptosis.     

毛发移植进展

目的:综述毛发移植的研究进展。方法:采用文献回顾和综合分析方法。结果:毛发移植有许多新的术式、新设备出现,毛发移植的基础研究已达到分子和基因水平,然而毛囊干细胞的研究和毛囊体外培养的临床应用还很不成熟。结论:毛发组织工程学的重大突破将提供更好的毛发移植技术,对整形科技极具现实意义。     

Persistence of chromosome aberrations in peripheral lymphocytes from Hodgkin's lymphoma remission patients

Purpose : To analyse spontaneous and in vitro bleomycin-induced chromosome aberrations in peripheral lymphocytes taken from Hodgkin's disease patients after prolonged (up to 31 years) remission periods, and to consider these data from the point of view of the carcinogenic potential of anticancer therapy. Materials and methods : Conventional analysis of chromosome preparations stained with azure-eosin. Results : The mean frequency and patterns of both spontaneous and induced aberrations in remission patients were significantly different from comparison groups (healthy donors and primary Hodgkin's disease patients). Individual values were characterized with high variation and did not show correlation with post-therapy time. New cancer cases diagnosed in remission patients were more frequent in subjects with high chromosome sensitivity to in vitro bleomycin challenge than in patients whose sensitivity to bleomycin was at a control level. Conclusions : The results are interpreted as suggesting that the tumorigenic potential of radiochemotherapy is mediated via induction of genetic instability in exposed cells. Long after the therapy, the instability may become an initiating event in the development of new malignancies in affected tissues, whereas the instability induced in haemopoietic stem cells may reveal itself in peripheral lymphocytes derived from formerly exposed precursors.     

山羊牙釉质电子自旋共振的剂量学特性

目的 探讨山羊牙釉质电子自旋共振(ESR)的剂量学的特性.方法 采用机械和化学处理相结合的方法,制备5组不同年龄的山羊牙釉质样品.用137 Cs γ射线照射山羊牙釉质样品,使用ESR波谱仪测量辐射前和不同辐射剂量后不同牙釉质样品的ESR信号.结果 137Cs γ射线照射前,山羊牙釉质所固有的ESR本底信号平均值为21.5,明显低于人的平均本底强度水平39.5;与人牙釉质相同,山羊牙釉质照射后产生的剂量学信号的强度与照射剂量线性相关,5组100 mg山羊牙釉质样品,其剂量学峰的辐射灵敏度的平均值为(34.3±1.9)/Gy,与人牙釉质样品的辐射响应平均值36.3/Gy非常接近.结论 人类牙釉质样品缺乏时,可以用相同辐射环境中的山羊牙釉质作为替代品进行剂量重建,为正确地评价辐射事故剂量提供科学依据.

Abstract：

Objectlve To study the properties of goat tooth enamel electron spin resonance (ESR)dosimetry.Methods Tootll enamel samples of goats were achieved by combined mechanical and chemical treatment at the ages of l,2,3,5,and 6 years.respectively and 9 enamel samples of adult molar were obtained.These enamel samples were exposed to 137Cs γ-rays at the cumulative doses of 0,0.5,1.0,2.0,and 5.0 Gy,respectively.ESR spectra Was measured before and after exposure.Results The background signal of goat tooth samples W88 21.5,significantly lower than that of the adult molar samples(39.5).The dusimetric signal intensity of the goat enamel increased with the radiation dose in a linear manner just as that of the human molars.The average radiation sensitivity of the goat tooth samples was(34.3±1.9)/Gy,close to that of the human tooth samples.Conclusions Goat teeth can be used for retrospective radiation dose reconstruction when human teeth are unavailable,in order to previde scientific data for dose reconstruction accurately.     

Biological effects of three types of ionizing radiation on creeping bentgrass

Abstract

Purpose: Gamma-rays and carbon ions are frequently used for mutation breeding in diverse plant species, whereas proton ions have been rarely used for this purpose. This study assessed the potential of proton ions for plant mutation breeding.

Materials and methods: We compared the effects of radiation on creeping bentgrass seeds with γ-rays, proton ions, and carbon ions on seed germination, plant growth parameters, and DNA fragmentation.

Results and conclusions: The lethal dose 50 (LD₅₀) doses based on seed germinability were 115.9?Gy (γ-rays), 225.1?Gy (proton ions), and 57.7?Gy (carbon ions). Threshold doses for survival were 150?Gy (γ-rays), 150?Gy (proton ions), and 25?Gy (carbon ions). Suppression of plant growth was displayed at 100?Gy (γ-rays), 25?Gy (proton ions), and 25?Gy (carbon ions). Similar patterns of decreasing head DNA percentage were observed for γ-rays and proton ions. Carbon ions induced the lowest frequency of DNA fragmentation. The biological effects of the ionizing radiation types on creeping bentgrass are summarizable as follows: germination, carbon ions (C)>γ-rays (G)>proton ions (P); survival, C?>?P?=?G; growth, C?≥?P?>?G; DNA fragmentation, G?≥?P?>?C. These results indicate that proton ions are useful as a physical mutagen in plant mutation breeding.     

Study of Several Factors in RNA-protein Cross-link Formation Induced by Ionizing Radiations Within 70S Ribosomes of E. Coli MRE 600

Summary

The induction of RNA-protein crosslinks in E. coli 70S ribosomes by γ-irradiation was studied by measuring the dependence of cross-link formation on ribosome concentration. The inverse dependence of cross-link percentage upon concentration up to at least 20 A_260nm units ml^?1 indicate that indirect effects seem to play a more major part than direct effects for these ribosome concentrations. The effect of various gases and free radical scavengers was used to determine the roles of the radicals H·, CO^?₂·, OH· and e^?_aq and to estimate their relative efficiencies for cross-links. They were found to be: 7·2(H·), 6(CO^?₂·), 2(OH·) and 1(e^?_aq). The extent of RNA–protein cross-link production in 70S ribosomes induced by γ-rays and neutrons in the presence and absence of oxygen was also investigated. Cross-link formation was estimated by separation of linked and unlinked material on nitrocellulose filters or after separation by SDS-sucrose gradient centrifugation under dissociating conditions. Oxygen inhibited cross-link formation by both neutrons and γ-rays. However, very few cross-links were formed in de-aerated solutions by exposure to neutrons, compared to those produced by γ-rays under the same conditions. This suggests that molecular oxygen generated along the secondary particle track can reduce the formation of RNA–protein cross-links.     

Low dose gamma-irradiation differentially modulates antioxidant defense in liver and lungs of Balb/c mice

Purpose: To evaluate the effect of low-dose (<50 cGy) whole body γ-irradiation on the antioxidant defense system in the liver and the lungs of mice at various post-irradiation intervals.

Materials and methods: Male Balb/c mice, 5 – 6 weeks of age, were divided into irradiated and non-irradiated groups. Whole body irradiation was done with γ-rays from a ⁶⁰Co source at doses of 10, 25 and 50 cGy (48.78 cGy/min). Lipid peroxidation and antioxidant status were measured in the liver and the lungs at 4, 12 and 24 h after irradiation.

Results: Lipid peroxidation increased by 1.38 and 2.0 fold in lung and liver respectively at 12 h after exposure to 25 cGy. Whole body exposure to 25 and 50 cGy significantly (p < 0.05) increased the hepatic reduced glutathione at 4 h. Reduced glutathione continued to rise until 12 h and returned to the basal level at 24 h, whereas in the lungs it remained elevated until 24 h at 10 and 25 cGy. Antioxidant enzymes activities for superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase increased by 1.22, 1.13, 1.22 and 1.11 fold respectively (p < 0.05) in the liver at 4 h after exposure to 50 cGy and remained elevated at almost the same level up to 12 h after exposure. Surprisingly these antioxidant defense enzymes remained unaltered in the lung at the above radiation doses.

Conclusions: Low-dose whole body γ-irradiation differentially modulates the antioxidant defense system in the liver and lungs of mice. The induction of endogenous glutathione, immediately after exposure to low-dose γ-irradiation, may be beneficial in protecting the cells from reactive oxygen species (ROS) induced oxidative stress.     

Usefulness of the SOS Chromotest in the study of medicinal plants as radioprotectors

Purpose: The aim of this work is to investigate the usefulness of a modified protocol of the SOS Chromotest to detect antigenotoxicity activities against γ-rays of plant extracts with proven antioxidant activity, and to elucidate the antigenotoxic mechanisms involved in radioprotection using this system.

Materials and methods: The methodology developed was assayed with amifostine, the most studied radioprotector, and with Phyllanthus orbicularis HBK, Cymbopogon citratus (DC) Stapf and Pinus caribaea Morelet extracts, using pre- and post-treatment procedures.

Results: The P. caribaea and C. citratus extracts were antigenotoxic against γ-rays when the cells were pre-treated with both extracts, suggesting a possible antigenotoxic action through a free radical scavenging mechanisms. Amifostine and the P. orbicularis extract were also antigenotoxic under pre- and post-treatment conditions, indicating that several antimutagenic components of this plant extract may also operate by some intracellular mechanism, unlike its antioxidant activity.

Conclusions: The results have demonstrated the usefulness of the modified SOS Chromotest assay in the screening of phytochemical radioprotectors as well as in the study of their antimutagenic mechanisms.     

香兰素衍生物VND3207对不同LET辐射致质粒DNA损伤的防护作用

目的 评价不同LET辐射致DNA损伤以及药物的防护作用.方法 分别以60Co γ射线、质子束、7Li重离子束照射溶液状态超螺旋构象质粒DNA,通过琼脂糖凝胶电泳分析DNA分子构象变化,检测DNA损伤程度及VND3207的防护作用.结果 质子和7Li重离子体外所致质粒DNA损伤明显比γ射线严重.药物VND3207能够有效减轻所观察的3种不同LET辐射对质粒DNA的损伤,加药组与不加药组相比,质粒DNA开环构象显著减少,保护效果随着药物浓度的增加更加明显.200 μmol/L浓度对50 Gy γ射线、质粒和7Li重离子辐照质粒DNA损伤的保护效果(质粒超螺旋构象百分比)分别为85.3%(t=3.70,P=0.033)、73.3%(t=10.58,P=0.017)和80.4%(t=8.57,P=0.008).可见VND3207对重离子辐射损伤的保护效应尤为显著,明显优于质子辐照损伤.结论 药物VND3207对辐射DNA损伤具有较好的保护作用,特别是对γ射线和重离子辐射损伤的保护作用更为明显.

Abstract：

Objective To evaluate the radioprotective effect of vanillin derivative VND3207 on DNA damage induced by different LET ionizing radiation.Methods The plasmid DNA in liquid was irradiated by 60Co γ-rays, proton or 7Li heavy ion with or without VND3207.The conformation changes of plasmid DNA were assessed by agarose gel electrophoresis and the quantification was done using gel imaging system.Results The DNA damage induced by proton and 7Li heavy ion was much more serious as compared with that by 60Co γ-rays, and the vanillin derivative VND3207 could efficiently decrease the DNA damage induced by all three types of irradiation sources, which was expressed as a significantly reduced ratio of open circular form (OC) of plasmid DNA.The radioprotective effect of VND3207 increased with the increasing of drug concentration.The protective efficiencies of 200 μmol/L VND3207 were 85.3% (t =3.70,P =0.033), 73.3% (t = 10.58, P =0.017)and 80.4% (t =8.57,P =0.008)on DNA damage induction by 50 Gy of γ-rays, proton and 7Li heavy ion, respectively.It seemed that the radioprotection of VND3207 was more effective on DNA damage induced by high LET heavy ion than that by proton.Conclusions VND3207 has a protective effect against the genotoxicity of different LET ionizing radiation, especially for γ-rays and 7 Li heavy ion.     

60Coγ射线诱导EJ细胞DNA损伤及γH2AX 表达的研究

目的 探讨不同剂量⁶⁰Coγ射线对EJ细胞DNA损伤的情况,不同剂量⁶⁰Coγ 射线照射EJ细胞后诱导磷酸化组蛋白H2AX焦点形成,以及与γH2AX表达量的关系。方法 单细胞凝胶电泳检测DNA链断裂损伤情况。免疫荧光法检测不同剂量γ 射线照射后立即、以及2 Gy γ 射线照射后不同时间的EJ细胞中γH2AX焦点的数量。流式细胞分析法检测不同剂量γ 射线照射后EJ细胞中γH2AX 蛋白表达量的变化。结果 单细胞凝胶电泳结果显示,γ射线照射后DNA损伤情况明显加重,随照射剂量的增加,细胞尾矩不断加大,0 Gy组尾矩为0.24,4 Gy照射组尾矩为5.26;免疫荧光结果显示,随着照射剂量的增加,γH2AX焦点数目及大小均明显增加,照射的剂量范围从0.1~4 Gy均可检测,且照射剂量和焦点形成数目之间存在剂量-效应关系,0.1 Gy照射组每个细胞中的焦点数平均达12.37个,4 Gy照射组每个细胞中的焦点数平均达46个;2 Gy γ 射线照射后24 h仍可检测到γH2AX焦点,随时间延长焦点数目减少、强度减弱,具有时间依赖性。流式细胞检测结果表明,γ 射线照射后γH2AX 蛋白表达量明显增加,呈现明显量效关系,0.1和4 Gy照射组γH2AX阳性细胞表达率分别为7.4%和29.2%。结论 免疫荧光法检测照射后γH2AX焦点数目比其他实验方法更能敏感、直观的反映DNA损伤及修复情况,有望成为检测辐射损伤的理想生物指标。