电离辐射对胸腺细胞周期进程的影响

本文采用流式细胞仪对小鼠Ｘ射线全照射后胸腺细胞周期进程与Ｘ射线剂量效应关系进行了研究，４．０ＧｙＸ射线全身照射后４ｈ胸腺细胞便出现明显的ＤＮＡ合成抑制和Ｇ２阻滞，８ｈＧ２阻滞达最高点，不同剂量全身照射的结果表明，低剂量（５０～１００ｍＧｙ）全身照射后胸腺细胞ＤＮＡ合成了能力增强，而高剂量全身照射后则出现明显的ＤＮＡ合成抑制，Ｇ２阻滞和有丝分裂延迟。     

EL一4细胞凋亡与细胞周期的辐射效应

采用流式细胞术（ＦＣＭ）研究了０．５、１、２、４ＧｙＸ射线照射后，小鼠淋巴瘤细胞ＥＬ一４的凋亡与细胞周期的剂量效应关系。结果表明：以上剂量照射后２４ｈ，Ｇ１期细胞呈剂量依赖性增加，出现明显的Ｇ１阻滞；而Ｓ期细胞则剂量依赖性减少；Ｇ２期出现明显的Ｇ２阻滞；细胞凋亡亦呈剂量依赖性增力。该结果提示：ＥＬ一４细胞经较高剂量ｘ射线照射后，出现明显的ＤＮＡ合成抑制和Ｇ２阻滞，致使ＥＬ一４细胞的有丝分裂延迟。统计分析表明：Ｇ１阻滞与细胞凋亡高度相关ｒ＝０．９１。     

电离辐射对小鼠胸腺和脾细胞MDM2mRNA和蛋白表达的影响

目的：探讨Ｘ射线全身照射诱导小鼠胸腺和脾细胞Ｇ１期阻滞的分子机制。方法：采用流式细胞术和斑点印迹杂交检测Ｘ射线全身照射后昆明系小鼠胸腺和脾细胞中ＭＤＭ２ｍＲＮＡ和蛋白表达的变化。结果：２ＧｙＸ射线全身照射后４～８ｈ小鼠胸腺细胞ＭＤＭ２蛋白的表达明显升高（Ｐ〈０．０５）。时效和量效观察发现,无论是７５ｍＧｙ还是１ＧｙＸ射线全身照射,小鼠胸腺和脾细胞中ＭＤＭ２ｍＲＮＡ水平在照后１～４８ｈ均未见明显变化     

75mGyX射线诱导小鼠胸腺细胞转录因子CREB,NF—kB及AP1？…

为了解低剂量Ｘ射线全身照射对小鼠胸腺细胞基因转录调控的影响。方法：采用凝胶电泳迁移率分析和寡核苷酸竞争抑制方法检测低剂量Ｘ射线对小鼠胸腺细胞基因转录调控的影响。结果；迁移率变化证实７５ｍＧｙ射线全身照射小鼠后４ｈ，胸腺细胞核蛋白提取物的转录因子ＣＲＥＢ及ＮＦ－ｋＢ与其基因启动部位增强子控制序列的结合活性分别增强６倍及４．３倍，ＡＰｌ增强２倍。     

低剂量X射线对荷瘤小鼠局部大剂量照射抑瘤作用的影响

目的：探讨低剂量全身照射对局部肿瘤大剂量照射抑瘤作用的影响。方法：采用昆明系小鼠皮下接种Ｓ１８０腹水肉瘤细胞为实验瘤模型；荷瘤小鼠局部１０Ｇｙ或２．５Ｇｙ×４次Ｘ射线照射前１２ｈ或２４ｈ接受５０，７５，１００和１５０ｍＧｙ全身照射，观察局部照后２１ｄ的肿瘤生长百分数。结果：５０，７５和１００ｍＧｙ全身照射可明显增强局部肿瘤大剂量照射的抑瘤效果；局部照前１２ｈ比２４ｈ接受低剂量照射的增强效应更明显；     

X射线全身照射对胸腺CD3_＋细胞的影响

本实验采用流式细胞术研究了不同剂量Ｘ射线全身照射对小鼠胸腺细胞亚组的影响。结果表明，胸腺细胞在成熟分化的不同阶段，具有不同的辐射敏感性，ＣＤ３＋细胞（即成熟的胸腺细胞）具有相对的辐射抗性。０．５、１．０、２．０Ｇｙ照射后２４小时，ＣＤ３＋细胞的相对比例呈剂量依赖性增高，但在４．０Ｇｙ照射后２４小时未进一步上升。     

X射线全身照射对胸腺CD3＋细胞的影响

本实验采用流式细胞术研究了不同剂量Ｘ射线全身照射对小鼠胸腺细胞亚组的影响。结果表明，胸腺细胞在成熟分化的不同阶段，具有不同的辐射敏感性，ＣＤ３＋细胞（即成熟的胸腺细胞）具有相对的辐射抗性。０．５，１．０，２．０Ｇｙ照射后２４小时，ＣＤ３＋细胞的相对比例呈剂量依赖性增高，但在４．０Ｇｙ照射后２４小时未进一步上升。     

低剂量辐射诱导遗传损伤适应性反应的时间效应

利用小鼠生殖细胞为实验材料，观察低剂量辐射诱导遗传损伤适应性反应的时间效应。结果表明：以５０ｍＧｙＸ射线为Ｄ１剂量，然后在不同间隔时间照射Ｄ２（１．５ＧｙＸ射线），其间隔时间在２４ｈ内的不同时间照射Ｄ２，精原细胞和初级精母细胞染色体畸变率下降，出现明显的适应性反应，以３～６ｈ为最佳；以５０ｍＧｙ×４的多次照射和慢性小剂量６０Ｃｏγ射线照射（累积剂量为１．１０Ｇｙ）为Ｄ１剂量，在照射后４０ｄ仍可出现适应性反应现象。说明，单次急性照射的适应性反应持续时间较短；而多次照射和慢性照射适应性反应持续时间较长。     

X射线全身照射对小鼠胸腺细胞p53、p21、GADD45及MDM2蛋白表达的影响

目的：观察电离辐射全身照射对小鼠胸腺细胞ｐ５３、ｐ２１、ＧＡＤＤ４５ 及ＭＤＭ２ 蛋白表达的影响。方法：采用间接免疫荧光标记,流式细胞术检测蛋白表达的变化。结果：２ Ｇｙ Ｘ射线照射后１～８ ｈ ｐ５３ 蛋白表达显著增高;照射后４～４８ ｈ ｐ２１ 蛋白表达显著增高;ＭＤＭ２ 蛋白在照后４ ｈ 及８ ｈ 显著增高;而ＧＡＤＤ４５ 蛋白表达在照后１～４８ ｈ 内无明显变化。结论：电离辐射可诱导胸腺细胞ｐ５３、ｐ２１ 及ＭＤＭ２ 蛋白表达增高。此结果将对辐射诱导胸腺细胞Ｇ１ 期阻滞的分子通路研究有重要意义。     

电离辐射对小鼠胸腺细胞蛋白质表达的影响

目的：观察低剂量Ｘ射线全身照射诱导小鼠胸腺细胞蛋白质表达变化及对细胞内外蛋白质交换的影响。方法：采用双向电泳方法。结果：７５ｍＧｙＸ射线全身照射小鼠后４ｈ,细胞浆出现４个新蛋白点、４个增强蛋白点及３个减弱蛋白点,正确细胞浆中的５个蛋白点在照射后消失。照射后细胞外液出现１个新蛋白点、１个增强蛋白点及１个减弱蛋白点。正常细胞上液中的３个蛋白 在照射后消失。正常细胞浆中的２个蛋白点在照射后分别减弱和消失     

Adaptive response of thymocyte apoptosis and cell cycle progression induced by low dose X-ray irradiation in mice

The dose-effect of adaptive response of thymocyte apoptosis and cell cycle progression induced by whole-body X-ray irradiation (WBI) was studied in male Kunming mice. The inductive doses (D1) were 25, 50, 75, 100 or 200 mGy 6 h before the challenging doses (D2) of 1.0, 1.5 or 2.0 Gy. The changes in the percentages of the thymocyte apoptotic bodies (TAB) and the cells in different phases of cell cycle were measured with flow cytometry. The percentages of TAB decreased, the arrests of G1 and G2 + M phases diminished, and the cells of DNA synthesis of S phase increased when the D1 + D2 groups was compared with the D2 groups. When D1 was 200 mGy, the adaptive response of thymocyte apoptosis and cell cycle progression were no longer induced by low dose radiation (LDR). In addition, the extracellular fluid from the splenocytes were cultured with Con A for 48 h in vitro 24 h after 75 mGy WBI was placed in the murine thymocyte suspension from mice irradiated with 2.0 Gy WBI and co-incubated. The thymocyte apoptosis decreased. Especially, noteworthy was that the percentages of TAB after the incubation for 72 h were significantly lower than those in 2.0 Gy irradiated thymocytes (P < 0.05). These results indicate that when the mice were irradiated with 25-100 mGy (D1, 12.5 mGy/min) 6 h before 1.0-2.0 Gy (D2, 0.287 Gy/min) exposure, an adaptive response of thymocyte apoptosis and cell cycle progression may be induced under the condition of WBI, and LDR (75 mGy) may change the microenvironment of immune cells and decrease the thymocyte apoptosis.     

不同剂量X射线诱导体内及体外小鼠巨噬细胞CD14的剂量效应关系

目的：观察不同剂量X射线照射在体内及体外对小鼠巨噬细胞CD14表达的影响。方法：采用流式细胞术检测巨噬细胞表面CD14阳性细胞数。体内实验选择16 h、体外实验选择4 h,低剂量为0.05～0.20 Gy、高剂量为0.5～6.0 Gy。 结果：整体照射时,低剂量X射线使CD14表达明显增强,而较高剂量X射线（大于2.0 Gy）明显抑制CD14表达;在体外照射时,0.075 Gy和2.000 Gy以内的较高剂量X射线也使CD14表达明显增强,而4.0~6.0 Gy 的剂量使J774A.1细胞的CD14表达明显受到抑制。 结论：低剂量X射线在体内及体外均能诱导小鼠巨噬细胞的CD14表达;小于2.0 Gy时也能增强CD14的表达,而剂量大于2.0 Gy时CD14的表达呈剂量依赖性下降,而且在体外的变化更明显。     

低剂量电离辐射对松果腺细胞周期的影响

目的 :探讨低剂量 X射线全身照射对小鼠松果腺细胞周期的影响。方法 :采用流式细胞术(FCM)检测小鼠松果腺细胞周期。结果 :低剂量电离辐射全身照射后 ,小鼠松果腺 G0 / G1期细胞百分数降低 (P<0 .0 5 ) ,S期细胞百分数升高 (P<0 .0 1) ,G2 + M期细胞百分数降低 (P<0 .0 5 )。结论 :低剂量电离辐射可促进小鼠松果腺细胞的 DNA合成及增殖。     

G1 Arrest and Relative Protein Expressions in Mouse Thymocytes Induced by Whole Body X-Ray Irradiation G1 Arrest and Relative Protein Expressions in Mouse Thymocytes Induced by Whole Body X-Ray Irradiation

Objective　To investigate the molecular regulation of G1 arrest of mouse thymocytes induced by ionizing radiation. Methods　Cell cycle was analyzed by flow cytometry (FCM) following staining of cells with proidium iodide. Fluorescent staining and flow cytometry analysis were employed for measurement of protein expression. Results　It was demonstrated that G1 phase of mouse thymocytes increased significantly at 12h after whole body irradiation (WBI) with the doses of 0.5, 1.0 and 2.0 Gy, and at 24h following 2.0Gy exposure, measured by FCM. In the time course experiment, it was found that G1 phase of thymocytes increased significantly at 4h, reached a peak level at 24h and came down toward 48h after WBI with 2.0Gy X-rays. The results also showed that after 2.0Gy exposure, the expression of proteins in mouse thymocytes increased significantlty from 1h to 8h for p53, for p21 from 4h to 48h, and for MDM2 at 4h and 8h, measured by FCM. But no change was found for GADD45 protein expression. Conclusion　These results suggest that G1 arrest could be induced by a single dose of 0.5 Gy, 1.0Gy or 2.0Gy, and its molecular control might be established through the p53-p21 pathway.     

Effects of whole body irradiation with X—rays on the expression of TfR on lymphocytes in spleens of mice

目的:通过研究不同剂量X射线全身照射后小鼠脾淋巴细胞运铁蛋白(TfR)表达的变化,探讨电离辐射后TfR对免疫功能的作用.方法:应用直接免疫荧光抗体和流式细胞仪检测TfR表达的变化.结果:75 mGy X射线全身照射后24 h和72 h,脾脏中TfR阳性表达细胞数显著增加;但1～6 Gy X射线全身照射后24 h,脾脏中TfR阳性表达细胞数显著减少.同时检测的IL-2活性显示出平行变化.结论:低剂量电离辐射时TfR增强免疫功能,而在高剂量电离辐射时TfR则抑制免疫功能.TfR表达的变化可能是因为电离辐射使IL-2活性改变所致.     

G1 Arrest and Relative Protein Expressions in Mouse Thymocytes Induced by Whole Body X—Ray Irradiation

Objective:To investigate the molecular regulation of G1 arrest of mouse thymocytes induced by ionizing radiation.Methods:Cell cycle was analyzed by flow cytomtry(FCM)following staining of cells with proidium iodide.Fluorescent staining and flow cytometry analysis were employed for measurement of protein expression.Results:it was demonstrated that G1 phase of mouse thymocytes increased significantly at 12h after whole body irradiation(WBI)with the doses of 0.5,1.0 and 2.0Gy,and at 24h following 2.0Gy exposure,measured by FCM.In the time course experiment,it was found that G1 phase of thymocytes increased significantly at 4h,reached a peak level at 24h and came down toward 48h after WBI with 2.0Gy X-rays.The results also showed that after 2.0Gy exposure,the expression of proteins in mouse thymocytes increased significantlty from 1h to 8h for p53,for p21 from 4h to 48h ,and for MDM2 at 4h and 8h.measured by FCM,But no change was found for GADD45 protein expression.Conclusion;These results suggest that G1 arrest could be induced by a single dose of 0.5Gy,1.0Gy or 2.0Gy,and its molecular control might be established through the p53-p21 pathway.     

X射线对小鼠腹腔巨噬细胞表达B7-1和B7-2的影响

目的 :观察 X射线全身照射对小鼠腹腔巨噬细胞表达 B7- 1和 B7- 2的影响。方法 :采用免疫组织化学法 ( ABC法 )。结果 :小鼠腹腔巨噬细胞表达 B7- 2达到高峰的时间早于 B7- 1,而且 B7- 2表达幅度也高于 B7- 1。剂量 -效应关系的研究表明 ,B7- 1和 B7- 2的表达均在 0 .0 75Gy剂量点出现峰值 ,而在较大剂量照射时也出现一个峰值。但在不同分度分析结果中发现 ,低剂量 X射线照射组的高密度细胞百分数比较大剂量组多。结论 :B7分子的表达上调可能是参与低剂量电离辐射免疫增强效应的重要因素。     

Radiationeffectsonthymocyteapoptosis

ＲａｄｉａｔｉｏｎｅｆｆｅｃｔｓｏｎｔｈｙｍｏｃｙｔｅａｐｏｐｔｏｓｉｓＬｉｕＳｈｕｚｈｅｎｇ，ＺｈａｎｇＹｉｎｇｃｈｕｎ，ＭｕＹｉｎｇ，ＬｉｕＪｉａｎｘｉａｎｇ（ＭＰＮＲａｄｉｏｂｉｏｌｏｇｙＲｅｓｅａｒｃｈＵｎｉｔ，ＰＲＣ）Ｒａｄｉａｔｉｏｎｅｆ...     

低剂量X射线对荷瘤小鼠局部大剂量照射抑瘤作用的影响

目的：探讨低剂量全身照射对局部肿瘤大剂量照射抑癌作用的影响。方法：采用昆明系小鼠皮下接种S180腹水肉瘤细胞为实验肿瘤模型；荷瘤小鼠局部10Gy或2．5Gy×4次X射线照射前12h或24h接受50，75，100和150mGy全身照射，观察局部照后21d的肿瘤生长百分数。结果：50，75和100mGy全身照射可明显增强局部肿瘤大剂量照射的抑瘤效果；局部照前12h比24h接受低剂量照射的增强效应更明显；局部肿瘤分割剂量照射比单次大剂量照射前的低剂量全身照射的增强效应更显著。结论：低剂量全身照射可增强局部肿瘤大剂量照射的抑癌作用，其增强效应的基本规律可能具有临床意义。