30MeV／u^40Ar^15＋和^60Coγ射线对有肝癌细胞株SMM…

比较了重离子３０ＭｅＶ／ｕ＾４０Ａｒ＾１５｜和＾６０Ｃｏγ射线对体外培养的人肝癌细胞株ＳＭＭＣ－７７２１的辐射效应，用活体和固定的方法观察了辐射处理后细胞死亡的过程。结果表明，无论是重离子还是γ射线，都能对细胞造成严重损伤，影响细胞存活百分数；同时，重离子比γ射线对细胞有更显著的杀伤效果，在处理后第４８ｈ，细胞存活率为５０％时，重离子的ＲＢＥ约为１．５．     

30MeV/u~(40) Ar~(15+) 和 ~(60)Co γ 射线对人肝癌细胞株 SMMC-7721 辐射效应的比较

比较了重离子３０ＭｅＶ／ｕ４０Ａｒ１５＋和６０Ｃｏγ射线对体外培养的人肝癌细胞株ＳＭＭＣ７７２１的辐射效应，用活体和固定的方法观察了辐射处理后细胞死亡的过程。结果表明：无论是重离子还是γ射线，都能对细胞造成严重损伤，影响细胞存活百分数；同时，重离子比γ射线对细胞有更显著的杀伤效果，在处理后第４８ｈ，细胞存活率为５０％时，重离子的ＲＢＥ约为１５。     

基于染色体畸变的细胞存活模型研究

为评估质子和重离子的辐射生物效应,建立了基于染色体畸变的细胞存活机理模型。开发了纳剂量生物物理蒙特卡罗模拟程序（NASIC）的DNA损伤修复模块,用于模拟不同射线类型、不同传能线密度（LET）辐射所致细胞核内染色体畸变产额。在分析辐射所致染色体畸变产额规律的基础上,建立了基于染色体畸变的细胞存活机理模型,并根据细胞存活实验数据拟合模型参数。以V79细胞为例,对于X射线和不同LET的质子,细胞存活分数的模型计算值与实验数据符合得很好,相关系数为0.985 3。采用⁴He离子的实验数据对模型及参数进行了验证,模型计算值与实验数据的相关系数为0.931 1。可见,模型能较好地区分不同射线类型、不同LET辐射在细胞致死效应上的差异。     

低剂量X射线照射诱导HeLa细胞存活的

采用集落形成法观察了低剂量X射线照射HeLa细胞的存活率，结果表明，小于0．5Gy的X射线照射细胞的存活率高于对照，得到了HeLa细胞存活的“兴奋效应”，而且在0．25Gy附近这种效应更为明显；低剂量D1（0．05，0．75Gy)的预照射降低了随后攻击量D2对细胞的损伤程度，反映出低剂量照射可诱发细胞存活的“适应性反应”。     

重离子照射肿瘤细胞的相对生物学效应值

对人肝癌细胞SMMC-7721细胞和黑色素瘤细胞A375细胞,进行80.55MeV 12C6 离子、X射线和γ射线照射,通过克隆存活实验获剂量-存活曲线,以X射线或γ射线为标准,计算重离子的相对生物学效应(Relative biological effectiveness,RBE ).结果显示,两种细胞的重离子RBE值都大于1,且分次照射的RBE大于单次照射.重离子照射SMMC-7721细胞的RBE高于A375细胞,分次照射的差异更明显.重离子具有独特的物理特性及高传能线密度(Line energy transfer,LET)下的强杀伤作用,可有效杀伤不同肿瘤细胞,减弱了细胞间的敏感性差异.临床的分次照射重离子治疗时,细胞的亚致死修复明显降低,可采取较少的照射次数达到杀伤肿瘤的目的,提高肿瘤治疗效率,减轻病人痛苦.     

中能碳离子束对不同贯穿深度上黑色素瘤B16细胞的辐照存活效应

测量了49．30MeV/u及经脊形过滤器展宽的Bragg峰的74.55MeV/u^12C离子束在不同贯穿深度上辐射后黑色素瘤B16细胞的存活率。结果显示,在以存活为终点的B16细胞生物学效应与碳离子束能量沉积同步增大。即Bragg或展宽的Bragg峰区内细胞存活率远低于离子束入射或出射通道处的细胞存活率。通过实验测量与剂量平均LET结合的线性平方模型理论计算存活曲线的比较,发现在实验测量误差范围内两者符合较好。提示：剂量平均LET结合线性平方模型可能是预测中能重离子束贯穿深度上B16细胞存活效应的一种有效的方法。     

12C6+离子辐照诱发人类肝L02细胞hprt基因突变的研究

本文研究12C6 离子辐照人类肝细胞系L02细胞诱发hprt基因突变与剂量的效应关系,为正确评价重离子对人体正常组织细胞的辐射风险及危害提供基础数据和依据.分别用12C6 离子束(LET为30 keV/μm)和X射线(LET为0.2 keV/μm)对L02细胞进行0～6Gy照射后,用克隆形成法检测细胞的存活分数,另外在含有6-TG的培养基中克隆、筛选hprt突变细胞株,测定突变频率.结果表明:12C6 离子辐照后L02细胞的存活分数明显小于X射线照后.两种射线照射后,每106个存活细胞中突变克隆的个数随照射剂量增大而增大,受照细胞的突变频率也都在1Gy处最大.但相对于X射线,人类肝细胞系L02细胞对高LET重离子辐射更敏感,而且12C6 离子束诱发更多的存活细胞hprt基因突变.     

混输脾基质细胞与骨髓细胞悬液在小鼠大剂量辐射损伤修复中的作用

Ｃ５７ＢＬ／６／小鼠经６０Ｃｏγ射线一次整体照射８Ｇｙ后，分成三组：（１）单纯照射８Ｇｙ组。（２）照射后单纯骨髓移植组，（３）照射后混输脾基质细胞（ＳＳＣ）与骨髓细胞（ＢＭＣ）组，以观察骨髓移植和回输脾基质细胞对大剂量照射后受体存活率及造血干细胞（ＣＦＵ－Ｓ）的影响，并初步探讨其可能的机理。结果表明：单纯骨髓移植组受体存活率比单纯照射组高出２７％；而照射后混输ＳＳＣ组之存活率比单照射组高４７％，比单纯骨髓移植组高２２％（Ｐ＜０．０５）。混输ＳＳＣ可明显提高脾ＣＦＵ－Ｓ、ＣＦＵ－Ｆ及ＡＮＡＥ染色（＋）（－）细胞数。在体外混合培养中脾基质细胞对实质细胞增殖起支持与调节作用。     

固体气泡损伤探测器探测高能重离子的研究

用高能重离子Ar和C进行的实验表明：（1）高能重离子可以在固体气泡损伤探测器中产生径迹,重离子径迹呈直线形,由一连串微小气泡组成;（2）固体气泡损伤探测器探测重离子具有阈特性,阈的实质近似为临界能量损失率（dE／dX）C,这一阈特性与蚀刻径迹探测器类似。固体气泡损伤探测器的阈值为（dE／dX）c=2220MeV／g·cm2,可用于重离子物理、宇宙射线和宇宙暗物质探测以及癌症治疗模拟等领域。     

酵母β-葡聚糖对人脐静脉内皮细胞的辐射防护作用

研究酵母β-葡聚糖(BG)对X射线辐照致人脐静脉内皮细胞(Eahy926)损伤的防护作用。用四甲基偶氮唑盐(MTT)法评价BG的Eahy926细胞毒性,筛选出BG的最佳浓度和作用时间(10μg/mL,24 h)。用克隆存活法分析BG对Eahy926细胞辐射敏感性的影响。在X射线辐照至吸收剂量2Gy后0.5和24 h,用流式细胞仪分析细胞凋亡分布、DNA损伤和细胞内活性氧(ROS)水平,并用试剂盒检测超氧化物歧化酶(SOD)活性和过氧化氢酶(CAT)活性。结果显示:BG对Eahy926细胞无毒性作用;与单独辐照组相比,BG预处理能减轻X射线辐射损伤,显著提高X射线辐照后细胞的克隆存活率;辐照后同一时间点,BG预处理组细胞DNA损伤、细胞凋亡率和细胞内ROS水平都明显低于单独辐照组;而BG预处理组细胞SOD和CAT酶活性均明显高于单独辐照组;在辐照后0.5和24 h,BG预处理组DNA损伤修复率高于单独辐照组。结果表明,BG对X射线造成的Eahy926细胞损伤有一定防护作用,其机制可能与BG清除细胞内自由基、提高抗氧化酶活性、减轻DNA损伤和细胞凋亡、促进DNA损伤修复有关。     

Modelling of Cellular Survival Following Chromosome Aberration

In order to assess the biological effectiveness of protons and heavy ions, a mechanistic model of cellular survival following radiation-induced chromosome aberrations was proposed. DNA damage repair module of nanodosimetry biophysical Monte Carlo simulation code (NASIC) was developed to simulate chromosome aberrations in nucleus induced by different types of particles at different linear densities of energy transfer (LET). Based on the analysis of radiation-induced chromosome aberration, a mechanistic model of cellular survival following radiation-induced chromosome aberrations was proposed. The parameters of the model could be obtained by fitting the experimental data of cell survival curves. For V79 cells exposed to X-rays and protons at different LET, the cell survivals calculated with the proposed model are in good agreement with the experimental data, and the correlation coefficient is 0.985 3. The proposed model was validated by experimental data of V79 cells exposed to ⁴He ions and the correlation coefficient of the cell survival calculated with the proposed model, and the experimental data is 0.931 1. The results show that the proposed model can distinguish the difference of cell survival for cells exposed to different types of particles at different LET.     

An important mechanism of crop breeding with ultralow energy ion implantation

The characteristic X-rays excited in carbon compounds of seeds by ultralow energy (110 keV) ions implanted in wheat seeds were simulated with carbon-light of synchrotron-radiation. After the seeds were irradiated with the C-light, the through-germination survival fraction of the seeds and the micronucleus frequency in their root-tip cells could be measured. The data verify that the characteristic X-rays excited by the ultralow energy ions implanted in the seeds provide an important mechanism of crop breeding.     

X射线辐照后人肝细胞、肝癌细胞存活与端粒酶活性关系的研究

利用X射线对体外培养的人肝癌细胞SMMC-7721和正常人肝细胞HL-7702进行辐照,以细胞克隆形成法测定细胞存活率,多聚酶链式反应银染端粒重复序列扩增法(Telomeric repeat amplification protocol,TRAP-PCR)检测细胞中端粒酶活性变化,探讨辐照后细胞存活与细胞中端粒酶活性变化的关系。结果表明,SMMC-7721和HL-7702细胞的存活率都随辐照剂量的增加而相应降低。在1-4Gy剂量范围内,两种细胞的端粒酶活性变化均呈剂量依赖性增强。但在1Gy、2Gy、3Gy剂量下,SMMC-7721其端粒酶活性较对照(0Gy)细胞低;当辐照剂量达4Gy时,端粒酶活性略高于对照细胞。在1-4Gy剂量范围内,HL-7702和SMMC-7721的细胞存活与端粒酶活性在变化趋势上呈负的关系。     

Bystander effect in human hepatoma HepG2 cells caused by medium transfers at different times after high-LET carbon ion irradiation

Although radiation-induced bystander effects have been well documented in a variety of biological systems, whether irradiated cells have the ability to generate bystander signaling persistently is still unclear and the clinical relevance of bystander effects in radiotherapy remains to be elucidated. This study examines tumor cellular bystander response to autologous medium from cell culture irradiated with high-linear energy transfer (LET) heavy ions at a therapeutically relevant dose in terms of clonogenic cell survival. In vitro experiments were performed using human hepatoma HepG2 cell line exposed to 100 keV/μm carbon ions at a dose of 2 Gy. Two different periods (2 and 12 h) after irradiation, irradiated cell conditioned medium (ICCM) and replenished fresh medium were harvested and then transferred to unirradiated bystander cells. Cellular bystander responses were measured with the different medium transfer protocols. Significant higher survival fractions of unirradiated cells receiving the media from the irradiated cultures at the different times post-irradiation than those of the control were observed. Even replenishing fresh medium for unirradiated cells which had been exposed to the ICCM for 12 h could not prevent the bystander cells from the increased survival fraction. These results suggest that the irradiated cells could release unidentified signal factor(s), which induced the increase in survival fraction for the unirradiated bystander cells, into the media sustainedly and the carbon ions triggered a cascade of signaling events in the irradiated cells rather than secreting the soluble signal factor(s) just at a short period after irradiation. Based on the observations in this study, the importance of bystander effect in clinical radiotherapy was discussed and incorporating the bystander effect into the current radiobiological models, which are applicable to heavy ion radiotherapy, is needed urgently.     

Apoptosis and necrosis of HeLa cells in response to low-energy ion radiation

1 Introduction The biological effects of the different kinds of radiation such as photons, α particles, electrons, and protons have been widely studied over 100 years. However, the interaction between the low-energy ions (with energy lower than 100 keV) and organisms was uncertain. Based on the concept that ions will penetrate into a dense matter, the depth range of the incident ions with such low energies is rather limited, and these may have little or no effect on organisms [1]. However, t…     

Non-destructive analysis of coins using high-energy PIXE

At the Ionenstrahllabor (ion beam laboratory) a great variety of ions with variable energies up to several MeV/u can be produced. Performing proton induced X-ray emission (PIXE) with protons of 68 MeV, heavy elements can be detected via the K X-rays in addition to their L X-rays. The large proton range and the small absorption coefficients for the K X-rays result in an analysable depth of several millimeters. The L–K line intensity ratio yields further information on the composition of the objects. The objects of the study were so-called “Wiener Pfennige” found in Tulln, Austria. The “hoard of Tulln” contains about 11 000 of these silver coins which were strongly corroded and agglomerated to a single block. After the restoration non-destructive analysis should provide information about the elemental composition. The goal was to show the evolution of the copper content of the coins and the verification of the actual coin classification.     

低剂量碳离子诱导的哺乳动物细胞适应性反应的研究

研究了高ＬＥＴ的碳离子对Ｖ７９细胞和Ｂ１６细胞的低剂量效应。细胞经０．０２Ｇｙ和０．０５Ｇｙ的诱导剂量处理后,继续培养４ｈ,再经１Ｇｙ攻击剂量处理,从存活率和微核率两方面研究了细胞的适应性反应。结果表明：经０．０２Ｇｙ诱导剂量处理以后,两种细胞在存活率和微核率方面分别表现为明显的提高和下降,相反,经０．０５Ｇｙ诱导剂量处理以后,细胞 存活率方面没表表现出有统计学意义的差别,在微核率方面表现出协同损     

The role of autophagy in cell survival from heavy ion irradiation in the plateau region

To study cytotoxic effect of heavy ion irradiation in the plateau region, and investigate whether autophagy in- duced by heavy ion irradiation is cytoprotective, HeLa cells were irradiated with 350 MeV/u carbon ions beams, and the clonogenic survival was analyzed. The results showed that cell survival decreased with increasing doses. It was also found that G2/M-phase cells increased, and the autophagy-related activity was significantly higher than the control. When autophagy was blocked by 3-methyladenine in carbon-ion irradiated cells, G2/M phase arrest and the percentage of apoptosis cells were further elevated, and cell survival decreased significantly, in- dicating the induction of cytoprotective autophagy by carbon-ion irradiation. Our results demonstrated that autophagy induced by carbon ion irradiation provided a self-protective mechanism in HeLa ceils, short-time inhibition of autophagy before carbon-ion irradiation could enhance radiation cytotoxicity in HeLa cells.     

Relationship between cellular radio-sensitivity and naked DNA damage in mammalian cells exposed to heavy ions

The relationship between deoxyribonucleic acid (DNA) damage and the cell death induced by ~(12)C ions irradiation was examined in four kinds of cells, Melanoma B16, cervical squamous carcinoma HeLa, Chinese hamster V79 and hepatoma SMMC-7721. Cell survival was determined by a colonogenic assay, and the sensitivity was described by D_(50)(the dose of radiation necessary to reduce the survival to 50%). For all cell lines, D_(50) ranged from 0.74 Gy to 3.85 Gy, among them B16 was the most radiosensitive to ~(12)C ions, and V79 and HeLa cells had almost the same radio-sensitivity, SMMC-7721 was the last. The induction of deproteinized DNA double-strand breaks induced by ~(12)C ions were measured by pulsed-field gel electrophoresis (PFGE), and the initial yield of the deproteinized DNA dsbs per unit dose was expressed as the DNA double break level (L). A linear dose-response curve was seen for initial DNA dsbs for all cell lines (slopes range from 0.40-0.98 (DSBs/100Mbp/Gy)). V79 was the steepest, B16 was the last.There was an inverse relationship between the initial DNA dsb and D_(50) if the B16 cell line was not considered, but there was no relativity even excludes the B16 cell line. The present results indicate that there is no relationship between cellular sensitivity and initial DNA dsb, even exclude the effects of chromatin structure.