mBAND analysis of chromosome aberrations in lymphocytes exposed in vitro to alpha-particles and gamma-rays

PURPOSE: To investigate the profiles of chromosome damage induced in vitro by exposure to alpha-particles and gamma-rays. MATERIALS AND METHODS: Human peripheral blood lymphocytes were exposed to three dose regimes: alpha-particle doses of 0.2 and 0.5 Gy and a gamma-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 alpha-particle irradiation is more likely to result in multiple breaks in a chromosome than gamma-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 alpha-particle dose. The ratio of interchanges to intrachanges (F ratio) was 1.4 and 2.4 for 0.2 and 0.5 Gy alpha-particles respectively and 5.5 for 1.5 Gy gamma-rays. Evaluation of simple versus complex exchanges indicated ratios of 1.9 and 2.7 for 0.2 and 0.5 Gy alpha-particles respectively and 10.6 for 1.5 Gy gamma-rays. The majority of the intrachanges involving chromosomes 5 induced by alpha-particle radiation were associated with more complex exchanges. CONCLUSIONS: This study has confirmed that exchanges induced by exposure to high linear energy transfer (LET) alpha-particle radiation comprise a greater proportion of intrachanges than those induced by exposure to low LET gamma-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.     

部分照射离体血对淋巴细胞染色体畸变形成的影响

目的 分析⁶⁰Coγ射线部分照射离体血对人外周血淋巴细胞染色体畸变形成的影响。方法 用2Gy⁶⁰Coγ射线37℃照射人外周血后以不同比例混合后进行培养、制片和分析染色体畸变。结果 染色体畸变随照射血比例的增加而增加,与单纯照射组相比,混合照射血的染色体畸变率高。1:1比例混合估算出的剂量为1.27Gy,大于1Gy;0.5:1比例混合估算出的剂量为0.93Gy,大于0.5Gy;而在1:0组,照射剂量与估算剂量基本一致。结论 染色体畸变可以作为估算非均匀照射的生物学指标之一。     

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.     

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.     

Effect of americium-241 alpha-particles on the dose-response of chromosome aberrations in human lymphocytes analysed by fluorescence in situ hybridization

PURPOSE: To evaluate by the fluorescent in-situ hybridization (FISH) technique the dose-response and intercellular distribution of alpha-particle-induced chromosome aberrations. In particular, the validity of using the yield of characteristic types of chromosome abnormalities in stable cells as quantitative indicators for retrospective dose reconstruction has been evaluated. MATERIAL AND METHODS: Monolayers of human peripheral lymphocytes were exposed at doses from 0.02 to 1 Gy to alpha-particles emitted from a source of americium-241. The most probable energy of the alpha-particles entering the cells was 2.7 MeV. FISH painting was performed using DNA probes for chromosomes 2, 4 and 8 in combination with a pan-centromeric probe. In complete first-division cells, identified by harlequin staining, aberrations involving painted target chromosomal material were recorded as well as aberrations involving only unpainted chromosomal material. RESULTS: In total, the percentage of complex aberrations was about 35% and no dose dependence was observed. When complex-type exchanges were reduced to simple base types, the different cell distributions were clearly over-dispersed, and the linear coefficients of the dose-effect curves for translocations were significantly higher than for dicentrics. For past dose reconstruction, only a few complex aberrations were in stable cells. The linear coefficient obtained for transmissible aberrations in stable cells was more than seven times lower than that obtained in all analysed cells, i.e. including unstable cells. CONCLUSION: FISH-based analysis of complex rearrangements allows discrimination between partial-body exposures to low-linear energy transfer radiation and high-linear energy transfer exposures. In assessing past or chronic exposure to alpha-particles, the use of a dose-effect curve obtained by FISH-based translocation data, which had not excluded data determined in unstable cells, would underestimate the dose. Insertions are ineffective biomarkers because their frequency is too low.     

Modification of bleomycin-induced chromosome aberrations by hyperthermia and under energy depleting conditions in human peripheral lymphocytes.

Synergistic effects of bleomycin (BLM) and hyperthermia were studied in human peripheral lymphocytes (HPL). The frequencies of breaks produced by BLM were dependent on dose, incubation temperature, and treatment time. Heat alone did not induce chromosome aberrations. Synergistic effects of heat and BLM occurred at 43 degrees C, either when hyperthermia was for 60 min following treatment with BLM or when hyperthermia was for 30 min simultaneously with BLM treatment. At incubation temperatures below 43 degrees C as many dicentric chromosomes as chromosome breaks were found, but about twice as many dicentric chromosomes as chromosome breaks were found when cells were treated with BLM at 43 degrees C for 60 min. In all experiments with BLM chromosomal anomalies were overdispersed. Comparison with unstimulated HPL, heated after X-irradiation, suggested that heat inhibits repair of BLM-induced lesions to a smaller extent than X-ray-induced lesions. Experiments with sodium azide and 2-deoxyglucose led to the conclusion that cellular uptake of BLM is partly energy-dependent. Additionally, an energy-independent uptake of BLM, which could not be blocked by inhibitors, was apparent.     

室内氡暴露居民外周血淋巴细胞DNA损伤及微核细胞发生率

目的：观察室内氡暴露居民外周血淋巴细胞DNA损伤及微核细胞发生率。方法：采用单核细胞凝胶电泳和微核检测两种方法。观察了我国甘肃省窑洞内氡暴露居民及对照居民外周血淋巴细胞DNA损伤及微核细胞发生率。结果：窑洞和普通住房居民（室内空气中氡浓度分别为200－350Bq.m^－3及37．5-77.1Bq.m^－3)的细胞迁移发生率分别为1．68％和1．43％，人发生细胞迁移百分别为57．1％和54．3％。50岁以上窑洞和普通住房居民细胞迁移和人发生细胞迁移率分别为2．14％、75．0％和2．00％、64．7％。窑洞和普通住房居民微核细胞发生率分别为1．07％和0．78％。结论：窑洞居民外周血淋巴细胞DNA损伤及微核细胞发生率略高于普通住房居民，P值接近0．05。     

上海“6.25”辐射事故受照射者12年后染色体畸变随访观察

目的对上海“6．25”5名^60Co源事故受照射者12年后的染色体畸变进行追踪观察，为辐射远后效应评价提供依据。方法常规染色体畸变分析、G显带自动核型分析和1号全染色体探针标记FISH方法，检测非稳定性畸变(Cu)和稳定性畸变(Cs)，并与照射后10年期的结果进行比较。结果Cu畸变已基本丢失，残存的畸变以易位为主；Cs畸变与复杂易位均与受照射剂量和受照射年龄相关，并随照射后时间推移缓慢下降。结论Cs畸变是评价辐射远后效应的较好指标，但需考虑年龄和时间对畸变造成的影响。     

M-FISH技术检测辐射诱导染色体易位和双着丝粒畸变

目的　探讨用多色荧光原位杂交 (M FISH)技术检测的易位和双着丝粒染色体畸变的差异。方法　用 1,2 ,3,7,8,9,14和 15号染色体端粒和着丝粒特异性探针的M FISH方法 ,分析6 0 Coγ射线离体照射的脐带血淋巴细胞染色体易位和双着丝粒畸变。结果　 (1)用M FISH方法分析6 0 Coγ射线诱导的易位和双着丝粒染色体畸变的剂量 效应曲线 ,均符合线性二次剂量效应模式 ;易位与双着丝粒的比值在大多数剂量水平不等于 1。 (2 )细胞中无非稳定性畸变的完全相互易位的比例随着吸收剂量的增加而降低。 (3)对大多数被标记染色体 ,3 0 0Gyγ射线照射诱发的染色体畸变观察值与理论值无差别 ;9号染色体畸变 (易位和双着丝粒 )观察值显著高于理论值 (P <0 0 5或P <0 0 1) ,15号染色体易位观察值显著低于理论值 (P <0 0 1)。结论　电离辐射诱导的染色体易位率不等于双着丝粒畸变率 ;对于大多数染色体 ,辐射诱发染色体易位率和双着丝粒畸变率符合随机性规律。     

Higher frequency of chromosome aberrations in late-arising first-division metaphases than in early-arising metaphases after exposure of human lymphocytes to X-rays in G 0

Purpose : To determine whether metaphases arising at different times after mitogen stimulation of G 0 lymphocytes differ in frequencies of X-ray-induced chromosome aberrations. Materials and methods : Human G 0 lymphocytes from peripheral blood exposed to 0, 1.5 or 3.0 Gy X-rays were stimulated to divide with the mitogen phytohaemagglutinin (PHA). First-division metaphases were distinguished from second and third divisions by chromatid labelling with 5-bromodeoxyuridine (BUdR) and staining with Giemsa or DAPI. Cultures harvested 48, 70 and 94 h after mitogen stimulation were analysed for unstable aberrations on Giemsa-stained slides and for stable and unstable aberrations by fluorescence in situ hybridization (FISH) with painting probes for chromosomes 1, 2 and 4. Results : Frequencies of aberrations declined at the later culture periods, as expected on the basis of unstable aberrations being lost in mitotic division. When scoring was restricted to first-division metaphases, however, aberration frequencies were higher in 94-h cultures than in 48-h cultures. Conclusions : Frequencies of radiation-induced chromosome aberrations in first-division metaphases increase with culture time after mitogen stimulation. Possible explanations for this finding are a delay of damaged cells in mitogenic response or progression through divisions and heterogeneity among lymphocytes in culture kinetics and radiosensitivity. The data argue against the common assumption that all first-division cells are equivalent as indicators of radiation-induced chromosome aberrations.     

Higher frequency of chromosome aberrations in late-arising first-division metaphases than in early-arising metaphases after exposure of human lymphocytes to X-rays in G0

PURPOSE: To determine whether metaphases arising at different times after mitogen stimulation of G0 lymphocytes differ in frequencies of X-ray-induced chromosome aberrations. MATERIALS AND METHODS: Human G0 lymphocytes from peripheral blood exposed to 0, 1.5 or 3.0 Gy X-rays were stimulated to divide with the mitogen phytohaemagglutinin (PHA). First-division metaphases were distinguished from second and third divisions by chromatid labelling with 5-bromodeoxvuridine (BUdR) and staining with Giemsa or DAPI. Cultures harvested 48, 70 and 94 h after mitogen stimulation were analysed for unstable aberrations on Giemsa-stained slides and for stable and unstable aberrations by fluorescence in situ hvbridization (FISH) with painting probes for chromosomes 1, 2 and 4. RESULTS: Frequencies of aberrations declined at the later culture periods, as expected on the basis of unstable aberrations being lost in mitotic division. Whe n scoring was restricted to firstdivision metaphases, however, aberration frequencies were higher in 94-h cultures than in 48-h cultures. CONCLUSIONS: Frequencies of radiation-induced chromosome aberrations in first-division metaphases increase with culture time after mitogen stimulation. Possible explanations for this finding are a delay of damaged cells in mitogenic response or progression through divisions and heterogeneity among lymphocytes in culture kinetics and radiosensitivity. The data argue against the common assumption that all first-division cells are equivalent as indicators of radiation-induced chromosome aberrations.     

非铀金属矿井下矿工外周血淋巴细胞的染色体畸变分析

目的 分析非铀金属矿山井下矿工外周血淋巴细胞染色体畸变情况及其影响因素。方法 按照2021年河南省放射卫生监测项目工作方案,分别选取河南省某铁矿和某金矿工作人员135人作为观察对象,两种金属矿井上作业人员69人作为井上组,井下矿工66人作为井下组。采用固体径迹探测器累积测量矿山作业场所氡浓度;常规法检测外周血淋巴细胞染色体畸变,分析对染色体畸变的影响因素。结果 井上作业场所氡浓度为30~2 943 Bq/m³,井下作业场所氡浓度为62~28 314 Bq/m³。井下组的年龄明显低于井上组(t=2.12,P<0.05),但井下组的双着丝粒体(dic)率、易位(t)率、无着丝粒体(ace)率和染色体型总畸变率明显高于井上组(χ²=10.49、16.74、8.15、29.50,P<0.01);仅以男性作业人员作为观察对象,两组比较得到一致的结果(χ²=8.44、11.63、4.94、20.81,P<0.05)。井下矿工的t率随工龄增加有升高趋势,不同工龄组间的差异有统计学意义(χ²=8.44,P<0.05)。Poisson回归分析显示,井上和井下分组是影响dic、t、ace和染色体型总畸变水平的因素(井下组的IRR=3.25、2.69、1.97、2.18,P<0.05)。结论 非铀金属矿井下作业场所的氡暴露可能是影响矿工染色体型畸变率升高的主要因素,对暴露于高氡环境矿工的职业健康与安全值得受到高度关注。     

Analysis of chromosome aberrations in nuclear-power-plant workers considering the lifetime of lymphocytes

PURPOSE: To analyse chromosome aberrations in nuclear-power-plant workers taking account of the mean lifetime of lymphocytes (MLTL). MATERIALS AND METHODS: Analysis of chromosome aberrations was performed on peripheral lymphocytes from 395 nuclear-power-plant workers and 135 controls. An equivalent acute dose (EAD) was calculated utilizing MLTL values of either 4.3 or 10 years. RESULTS: Using an MLTL value of 10 years produced an EAD range of 0.O1 mSv -182mSv(mean 46.6mSv), while using an MLTL, of 4.3 years produced results ranging from 0.01 mSv to 86.2 mSv (mean 23.4 mSv). A significant increase of chromosome-type exchange by the equivalent acute dose was observed using an MLTL of either 10 or 4.3 years when including the control in the analysis, but a significant increase was not seen when only the exposed was considered. A significant increase of chromosome-type deletion by EAD was seen even when only the exposed group was considered. CONCLUSIONS: EAD values based on an MLTL of either 4.3 or 10 years, as well as cumulative dose, showed no significant association with chromosome aberrations, when radiation workers only were analysed. The narrow dose range examined in this study might have contributed to this finding.     

Analysis of chromosome aberrations in nuclear-power-plant workers considering the lifetime of lymphocytes

Purpose : To analyse chromosome aberrations in nuclear-power-plant workers taking account of the mean lifetime of lymphocytes (MLTL). Materials and methods : Analysis of chromosome aberrations was performed on peripheral lymphocytes from 395 nuclear-power-plant workers and 135 controls. An equivalent acute dose (EAD) was calculated utilizing MLTL values of either 4.3 or 10 years. Results : Using an MLTL value of 10 years produced an EAD range of 0.01 mSv - 182 mSv (mean 46.6 mSv), while using an MLTL of 4.3 years produced results ranging from 0.01 mSv to 86.2 mSv (mean 23.4 mSv). A significant increase of chromosome-type exchange by the equivalent acute dose was observed using an MLTL of either 10 or 4.3 years when including the control in the analysis, but a significant increase was not seen when only the exposed was considered. A significant increase of chromosome-type deletion by EAD was seen even when only the exposed group was considered. Conclusions : EAD values based on an MLTL of either 4.3 or 10 years, as well as cumulative dose, showed no significant association with chromosome aberrations, when radiation workers only were analysed. The narrow dose range examined in this study might have contributed to this finding.     

放射性核素内照射诱发大鼠外周血淋巴细胞HPRT基因位点突变与染色体畸变的研究

目的 阐明放射性核素内照射诱发外周血淋巴细胞HPRT基因位点突变的剂量效应关系, 并与染色体畸变剂量效应关系进行比较。方法 给动物尾静脉注射放射性核素, 注射量为0.5ml/100g体重。剂量效应关系组动物注射活度为3.64×10⁵Bq/ml, 于注射后1、3、6和9d心脏穿刺取血。剂量率效应关系组动物注射活度分别为3.64×10⁵、1.82×10⁵、0.91×10⁵和0.445×10⁵Bq/ml, 于注射后3、6.7、17和42d心脏穿刺取血。应用多核细胞法及胞质分裂阻断法(CBMN)和常规染色体畸变分析法检测HPRT基因位点突变率和染色体畸变率。用计算机拟合剂量效应关系和剂量率效应关系函数。结果 淋巴细胞HPRT基因位点突变率不仅随内照射剂量和剂量率增加而增加, 呈现出良好的正相关, 而且与染色体畸变亦呈现出较好的相关性。结论 辐射诱发HPRT基因位点突变有可能成为有效的辐射生物剂量计。     

放射性核素内照射诱发大鼠外周血淋巴细胞HPRT基因 …

阐明放射性素核内照射诱发外周血淋巴细胞ＨＰＲＴ基因位点突变的剂量效应关系,并与染色体畸变剂量效应关系进行比较。方法给动物尾静脉注射放射性核素,注射量为０．５ｍｇ／１００ｇ体重。剂量效应关系组动物注射活度为３．６４＊１０＾５Ｂｑ／ｍｌ,于注射后１、３、６和９ｄ心脏穿刺取血。