双着丝粒染色体自动分析生物剂量估算研究

目的 基于遗传工作站,探讨建立双着丝粒染色体自动分析剂量-效应曲线,实现高通量自动化生物剂量估算。方法 使用⁶⁰Co放射源对3名健康志愿者外周血进行离体照射,常规培养、制片。使用遗传工作站进行染色体中期分裂相采集及双着丝粒自动分析,并人工确认,拟合双着丝粒染色体自动分析剂量-效应曲线。使用另一组不同剂量照射的离体外周血样本对拟合的双着丝粒染色体自动分析剂量-效应曲线进行准确性验证。结果 拟合的双着丝粒染色体自动分析剂量-效应曲线为Y=0.018 06D²+0.012 79D+0.000 489 1（R²=0.961）,该剂量-效应曲线可以准确地进行生物剂量估算,并且每例人工分析时间仅需数分钟。结论 成功地建立了新的双着丝粒染色体自动分析生物剂量估算方法,可以大量节省人工分析时间,对大规模核事故应急具有重要意义。     

基于人工智能的双着丝粒染色体识别算法初步研究

目的:为解决双着丝粒染色体人工分析费时费力的问题,探索人工智能技术,提出一种实现双着丝粒染色体自动识别的算法,从而实现快速高通量生物剂量估算。方法:结合人工智能和图像处理技术,基于MATLAB软件,通过研究图像预处理、阈值分割、二值化处理、区域标识、卷积神经网络和双着丝点识别算法,定义模糊隶属度函数来描述每条染色体属于...     

双着丝粒体半自动与人工分析估算生物剂量的比较研究

目的 通过对双着丝粒体（dicentrics,dic）半自动和人工分析估算剂量的比较,探讨dic半自动分析估算剂量的优势和应对大规模核与辐射事故临床分类诊断的可行性。方法 ⁶⁰Co γ射线离体照射两名健康男性的外周血样品,照射剂量为0、0.5、1、2、3、4、5和6 Gy,吸收剂量率为0.27 Gy/min,常规培养、制片;用高通量染色体自动扫描系统采集染色体中期高倍图像,用DCScore软件自动分析dic,用Ikaros软件人工计数dic+环（r）,拟合基于每细胞dic或dic+r数的剂量-效应曲线,并用本实验室参加全国生物剂量估算比对的12份考核样品（0.7~4.5 Gy）估算剂量进行验证。结果 半自动和人工分析检测到的每细胞dic或dic+r数均随照射剂量的增加而升高,显示量效关系有差异（r=0.984、0.972、0.972,P<0.01）;基于每细胞dic或dic+r数拟合的3条剂量曲线均具有较为理想的拟合度（R²=0.998、0.999、0.999,P<0.01）。验证结果显示,在验证样品的照射剂量>2 Gy时,人工确认前基于自动分析dic估算的剂量与实际照射剂量的相对偏差均<21%,dic经人工确认后估算的剂量均接近于实际照射剂量（相对偏差≤±10%）,而人工分析估算的剂量除0.7 Gy剂量点相对偏差为-25.71%,其他剂量点亦接近于实际照射剂量,但半自动分析可将剂量估算效率提高6倍。结论 dic半自动分析能明显提高生物剂量估算的水平和效率,可应对发生大规模核辐射事件医学应急响应临床分类诊断的需要。     

染色体畸变自动计数技术研究近况

用双着丝粒畸变率估算人员受照剂量是公认的较为可靠的方法。应用自动寻找中期分裂细胞和自动计畸变数的系统观察染色体样本可以大大提高工作效率。本文扼要介绍了自动计数系统的核心技术，即用计算机对数字化染色体图像自动分割和自动寻找畸变染色体及其在国内外的研究现状。     

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。     

不同结构类型双着丝粒体建立的剂量-效应曲线估算剂量可行性研究

目的 探讨基于不同结构类型双着丝粒体（dicentrics,dic）建立的剂量-效应曲线估算生物剂量的可行性。方法 采集两名健康人外周血样品,用0、0.5、1、2、3、4、5和6 Gy ⁶⁰Co γ射线（剂量率为0.27 Gy/min）离体照射人外周血,常规培养、收获和制备染色体标本,镜下分析并记录不同结构类型dic;应用CABAS软件建立dic剂量-效应曲线;并对两验证样本进行剂量估算。结果 不同结构类型dic率均随受照剂量的增加而升高（R²=0.886~0.943,P<0.01）,各剂量点经典型和单端型dic构成比之和约占所有类型dic的92%以上,而近距型dic和双端型dic分别在各照射剂量点的构成比均<4%。不同结构类型dic剂量-效应曲线的R²值均达到0.998;应用4条曲线估算的受照射剂量差异无统计学意义（P>0.05）。经典型dic剂量-效应曲线估算较高剂量时（3.9 Gy）,相对偏差均≤13.08%。结论 基于不同结构类型dic建立的剂量-效应曲线具有估算生物剂量的可行性。     

染色体着丝粒探针的制备及其在检测染色体畸变中的应用

人类染色体的着丝粒区含有多种高度重序列家族，其中α卫星ＤＮＡ在每号染色体的着丝粒区都存在，它们由１７１ｂｐ长的重复序列单元构成，其中大部分序列高度保守［１］。本文通过简并引物扩增１７１ｂｐ的重复单元，生物素标记制备成着丝粒探针，并应用此探针对辐射诱发...     

染色体易位分析在回顾性生物剂量重建中的研究进展

外周血淋巴细胞染色体易位分析用于日本原爆幸存者、早先核与辐射事故受照者回顾性剂量重建已有近40年的发展史,其应用价值已得到国际学界的广泛认可。随着mFISH、dGH等分子细胞遗传学技术的发展,国际上更多关注的是受到长期慢性低剂量暴露的放射工作人员、早年参加核爆炸实验的退伍军人和医疗照射受照者等暴露人群的生物剂量的估算与...     

染色体畸变自动计数技术研究近况

用双着丝粒畸变率估算人员受照剂量是公认的较为可靠的方法，应用自动寻找中期分裂细胞和自动计畸变数的系统观察染色体样本可以大大提高工作效率。本文扼要介绍了自动计数系统的核心技术，即用计算机对数字化染色体图像自动分割和自动寻找畸变染色体及其在国内外的研究现状。     

Canadian Cytogenetic Emergency Network (CEN) for biological dosimetry following radiological/nuclear accidents

Purpose: To test the ability of the cytogenetic emergency network (CEN) of laboratories, currently under development across Canada, to provide rapid biological dosimetry using the dicentric assay for triage assessment, that could be implemented in the event of a large-scale radiation/nuclear emergency.

Materials and methods: A workshop was held in May 2004 in Toronto, Canada, to introduce the concept of CEN and recruit clinical cytogenetic laboratories at hospitals across the country. Slides were prepared for dicentric assay analysis following in vitro irradiation of blood to a range of gamma-ray doses. A minimum of 50 metaphases per slide were analyzed by 41 people at 22 different laboratories to estimate the exposure level.

Results: Dose estimates were calculated based on a dose response curve generated at Health Canada. There were a total of 104 dose estimates and 96 (92.3%) of them fell within the expected range using triage scoring criteria. Half of the laboratories analyzed 50 metaphases in ≤ 1 hour and the time to score them was proportional to dose. The capacity and scoring expertise of the various participating laboratories were found to be generally acceptable.

Conclusions: The dose estimates generated through triage scoring by this network were acceptable for emergency biological dosimetry. When this network is fully operational, it will be the first of its kind in Canada able to respond to radiological/nuclear emergencies by providing triage quality biological dosimetry for a large number of samples. This network represents an alternate expansion of existing international emergency biological dosimetry cytogenetic networks.     

儿童脉管性疾病患者介入手术后外周血淋巴细胞染色体畸变观察

目的:评估儿童脉管性疾病患者在介入手术过程中接受的电离辐射(IR)对患儿染色体畸变的影响。方法:在知情同意的条件下,于介入术前和术后立刻采集26名患儿的外周血1.2 ml,培养制备染色体,分析外周血淋巴细胞染色体畸变情况。结果:儿童介入术后双着丝粒染色体+着丝粒环(dic+r)率明显增加,与术前比较,差异有统计学意义(...     

早熟染色体凝集技术作为生物剂量计的研究

早熟染色体凝集技术作为生物剂量的测定,利用冈田酸、花萼海绵体诱癌素A孵育非刺激人淋巴细胞诱导早熟染色体凝集取代中期细胞融合的办法,能简便、精确地检测出由辐射诱导的早期损伤。     

早熟染色体凝集技术作为生物剂量计的研究

早熟染色体凝集技术作为生物剂量的测定，利用冈田酸、花萼海绵体诱癌素A孵育非刺激人淋巴细胞诱导早熟染色体凝集取代中期细胞融合的办法，能简便、精确地检测出由辐射诱导的早期损伤。     

Automated scoring of dicentric chromosomes differentiates increased radiation sensitivity of young children after low dose CT exposure in vitro

Purpose: Automated detection of dicentric chromosomes from a large number of cells was applied to study age-dependent radiosensitivity after in vitro CT exposure of blood from healthy donors.

Materials and methods: Blood samples from newborns, children (2–5 years) and adults (20–50 years) were exposed in vitro to 0 mGy, 41 mGy and 978 mGy using a CT equipment. In this study, automated scoring based on 13,000–31,000 cells/dose point/age group was performed. Results for control and low dose points were validated by manually counting about 26,000 cells/dose point/age group.

Results: For all age groups, the high number of analyzed cells enabled the detection of a significant increase in the frequency of radiation induced dicentric chromosomes in cells exposed to 41 mGy as compared to control cells. Moreover, differences between the age groups could be resolved for the low dose: young donors showed significantly increased risk for induced dicentrics at 41 mGy compared to adults.

Conclusions: The results very clearly demonstrate that the automated dicentric scoring method is capable of discerning radiation induced biomarkers in the low dose range (<100 mGy) and thus may open possibilities for large-scale molecular epidemiology studies in radiation protection.     

Genome damage in testicular seminoma patients seven years after radiotherapy

Abstract

Purpose: Testicular seminoma cancer incidence has significantly increased over the last few decades, and although it is successfully treated by radiotherapy, long-term health risks are still unclear. The aim of the study was to show long-term genome damage in patients with seminoma after radiotherapy.

Materials and methods: Chromosome aberration (CA) and micronucleus (MN) assays seven years after radiotherapy with a total dose of 25 Gy were conducted in 10 testicular seminoma patients aged 23–49 years and results were compared with 10 healthy control subjects matched for age and smoking status.

Results: Although mean CA frequency did not deviate from control values, significantly increased frequencies of dicentrics, double minutes, and ring chromosomes were detected in seminoma patients. MN frequency in binuclear lymphocytes of patients was similar to controls (4.60/1000 vs. 5.82/1000, respectively). Significantly higher MN frequency was detected in mononuclear lymphocytes of patients than in controls (2.55/1000 vs. 0.73/1000, respectively). Average percentage of centromere-positive MN was 62.6% in seminoma patients.

Conclusion: This study shows the persistence of unstable CA in seminoma patients seven years after radiotherapy and the relevance of long-term follow up. MN frequency in mononuclear lymphocytes was shown to be relevant biomarker of long-term genome damage.