“Radiation Hormesis”中的剂量率效应

为了揭示不同剂量率Ｘ射线低剂量全身照射对低剂量辐射兴奋效应（Ｒａｄｉａｔｉｏｎ Ｈｏｒｍｅｓｉｓ）的影响，采用不同剂量率（１２．７ｃＧｙ／ｍｉｎ和０．２Ｇｙ／ｍｉｎ）对Ｂａｌｂ／ｃ小刀进行低剂量全身照射，研究了低剂量辐射兴奋效应中的剂量率效应。结果表明：采用不同剂量率Ｘ射线照射同一剂量时，所引起的生物效应不同。剂量率为１２．７ｍＧｙ／ｍｉｎ时，脾细胞＾３Ｈ－ＴｄＲ参入量对ＣｏｎＡ的反应性明显增强，     

低剂量电离辐射对小鼠脾巨噬细胞功能的影响

本研究采用昆明小鼠，低剂量Ｘ射线全身照射５０－２５０ｍＧｙ，剂量率１２．５ｍＧｙ／ｍｉｎ。停照后不同时间处死动物，取出脾脏，用贴壁法分离巨噬细胞和淋巴细胞，检测受照射脾ＭΦ的某些功能变化。     

低剂量电离辐射对小鼠脾巨噬细胞功能的影响

本研究采用昆明小鼠，低剂量Ｘ射线全身照射５０～２５０ｍＧｙ，剂量率１２．５ｍＧｙ／ｍｉｎ。停照后不同时间处死动物，取出脾脏，用贴壁法分离脾巨噬细胞（Ｍφ）和淋巴细胞，检测受照射脾Ｍφ的某些功能变化。结果表明，受照射的脾Ｍφ对受照射的脾淋巴细胞ＣｏｎＡ反应增强，ＩＬ一１分泌增多，抑瘤作用增高。     

低剂量X线全身照射对移植肿瘤的抑制作用

目的 研究低剂量Ｘ线身全照射的抑瘤作用，探讨最低有效抑瘤剂量。方法 利用ＮＩＨ系小白鼠在腹股沟区移植腹小型肝癌细胞株后第２天在剂量率为２０ｍＧｙ／ｍｉｎ条件下，给予不同剂量Ｘ线（０，５，１０，３０，５０，７５ｍＧｙ）单次全身照射，荷瘤１个月处死小鼠称瘤体质量，共重复６次实验。结果 ５０ｍＧｙ和７５ｍＧｙ组有明显的抑瘤效果（Ｐ〈０．０５），但该两组间无统计学差异，其余各组无显著抑瘤效果。结论 低剂量     

用Fura-2双波长荧光法测定低剂量电离辐射对小鼠脾细胞游离钙的影响

目的：探讨低剂量电离辐射免疫增强效应的机理。方法：采用Ｆｕｒａ－２／ＡＭ 双波长荧光测定法研究了低剂量电离辐射全身照射后小鼠脾Ｔ淋巴细胞内游离钙离子浓度（〔Ｃａ２＋ 〕ｉ）对次佳浓度Ｃｏｎ Ａ（５ ｍ ｇ／Ｌ）反应性的变化。结果：静息状态下的小鼠脾淋巴细胞内游离钙离子浓度为９５．０±１４．０ ｎｍ ｏｌ／Ｌ,ＣｏｎＡ 可使小鼠脾Ｔ淋巴细胞内游离钙离子浓度增加６９．４±７．６ ｎｍ ｏｌ／Ｌ,上升至峰值时间为７９．２ ｓ。７５、１００ 和２００ ｍ Ｇｙ 全身照射后２４ ｈ,Ｃｏｎ Ａ 诱导的小鼠脾Ｔ淋巴细胞内游离钙离子动员明显高于假照射组（Ｐ＜ ０．０１）。结论：低剂量电离辐射的免疫兴奋效应与其增强淋巴细胞内〔Ｃａ２＋ 〕ｉ动员等信息传递过程有关     

大剂量X线头部照射对大鼠免疫功能的影响

本实验采用Ｘ线头部照射（１、２、４和８Ｇｙ）动物模型，观察雄性大鼠照射后８ｈ免疫功能的变化。结构显示，胸腺细胞＾３Ｈ－ＴｄＲ自发掺入量（４和８Ｇｙ组）及对ＣｏｎＡ ＰＷＭ刺激的反应性（８Ｇｙ组）均增强（Ｐ＜０．０５）；脾细胞对ＣｏｎＡ刺激的反应性在各剂量组均呈降低趋势，其中４Ｇｙ组降低明显（Ｐ＜０．０５）；而脾细胞对ＰＷＭ刺激的反应性则相反，除２Ｇｙ组呈降低趋势外，其它各组均呈上升趋势（Ｐ＜０．０     

低剂量辐射离体照射诱导脾细胞免疫适应性反应的研究

观察低剂量辐射离体照射能否诱导小鼠脾细胞折免疫适应性反应。方法；采用＾３Ｈ－ＴｄＲ掺入法。结果：未发现０．０２５－０．０７５Ｇｙ低剂量辐射明显降低６ｈ后０．７５Ｇｙ或１．０Ｇｙ攻击剂量所致脾细胞裂原反应的损伤作用，而整体实验中上述照射条件则能诱导免疫适应性反应。     

电离辐射对淋巴细胞DNA合成的影响及适应性反应

目的：探讨淋巴细胞预先接受低剂量电离辐射后，对大剂量照射的适应性反应。方法：用０．０４８Ｇｙγ－射线照射后接受０．５￣８．０Ｇｙ攻击剂量照射，以＾３Ｈ－ＴｄＲ掺入法观察淋巴细胞ＤＮＡ合成能力的变化。结果：淋巴细胞接受低剂量照射时能提高被大剂量的ＤＮＡ合成４．０Ｇｙ的照射时适应性反应最充分。结论：低剂量辐射能诱导淋巴细胞对大剂量辐射的适应性反应。     

低剂量电离辐射诱导免疫适应性反应的时间效应

本研究采用Ｘ线全身照射昆明系雄性小鼠模型，观察电离辐射诱导免疫适应性反应的预照射剂量（Ｄ１剂量，７５ｍＧｙ）及其后损伤性剂量（Ｄ２剂量，１．５～２．０Ｇｙ）的时间效应。结果表明，Ｄ１与Ｄ２时间间隔６～４８ｈ，Ｄ２照后１８～２４ｈ可诱导胸腺细胞自发增殖能力及脾细胞对丝裂原（ＣｏｎＡ和ＬｐＰＳ）反应性等适应性反应。     

白血病骨髓移植前大剂量全身照射研究

１９８４年１２月至１９９１年４月应用全身照射技术对１６例白血病患者进行异体骨髓移植前的大剂量全身照射，均采用６０钴γ射线，用自行设计和制作的蜡板根据射线均匀度不一制成剂量均整装置，并且采用６次交替仰卧和侧卧的全身照射，使剂量均匀度在人体最高和最低剂量点仅相差８．２％。剂量率１．６５～５．４ｃＧｙ／ｍｉｎ，总剂量随剂量率的增加而递减，从９００ｃＧｙ降至６６０ｃＧｙ。结果：放射反应轻，生长发育影响小，生存质量较高，１、２和３年生存率分别为８１．３％（１３／１６）、７５．０％（９／１２）和６２．５％（５／８）。无一例发生间质性肺炎，仅１例出现骨髓排斥和复发。建议适宜剂量率４～５ｃＧｙ／ｍｉｎ，总剂量７００～８００ｃＧｙ。     

Effect of low dose radiation on subpopulations of lymphocytes and T cell subsets in mice

<正> The effect of radiation on lymphocyte subpopulations and T cell subsets of peripheral blood was studied in mice after X- and y-irradiation.lt was found that (1) there were neither marked changes in the percentage and absolute number of acid alpha-naphthol acetyl esterase "positive(ANAE + )cells of different granular patterns, nor significant lowering of the T11/Ts ratio after single whole body X-irradiation in the dose range of 25-250 mGy with a dose rate of 12.5mGy/min. At the same time no significant changes were found at different time intervals after irradiation. After continuous low level irradiation with 60Co γ-rays with a dose rate of 5.4 mGy/6h.d,the ANAE grauular pattern of lymphocytes showed no significant changes with cumulative doses of 32.4 -520 mGy. (3)There was no decrease in the "splenocyte Ts index in Kunming mice after low dose X-irradiation. The results suggest that the stimulatory effect of low dose radiation on the PFC reaction can not be explained on the basis of a decrease in num     

低剂量辐射诱导小鼠胸腺细胞DNA裂解适应性反应的剂量率效应

目的：观察低剂量辐射诱导胸腺细胞DNA裂解适应性反应的剂量率效应。方法：用X射线照射Kunming雄性小鼠,其诱导剂量（D1）及其后攻击剂量（D2）分别是75 mGy和1.5 Gy,D1剂量率为6.25、12.5、25、50、100和200 mGy•min^-1,D2剂量率为287 mGy•min^-1,D1 和D2间隔6 h。通过荧光分光光度计检测DNA裂解断片的变化。结果：D2组胸腺细胞DNA裂解率明显高于假照组（P<0.001）;当D1剂量率为6.25、12.5和25 mGy•min^-1,D1＋D2组DNA裂解率明显低于D2组（P<0.05或P<0.01）。 结论：当D1在75 mGy,剂量率为6.25～25 mGy•min^-1;D2为1.5 Gy,剂量率为287 mGy•min^-1;D1和D2间隔6 h,可在全身照射条件下诱导小鼠胸腺细胞DNA裂解的适应性反应。     

Mechanism of cytogenetic adaptive response induced by low dose radiation

Cytogenetic observation on human lymphocytes indicated that pre-exposure of 10, 50 and 75 mGy X-rays could induced the adaptive response. Experimental results with different temperature treatment showed that the adaptive response induced by low dose radiation could be enhanced by 41 degrees C and 43 degrees C, but inhibited by 4 degrees C in addition the treatment by 41 degrees C for one hour could also cause the adaptive response as did low dose radiation. Results showed that adaptive response induced by low dose radiation (10 or 50 mGy X-rays) could be eliminated by the protein synthesis inhibitor, implying that the adaptive response is related with the metabolism of cells, especially with the production of certain protective proteins.     

低剂量辐射对人骨髓间充质干细胞生物学特性的影响

目的：探讨低剂量辐射（LDR）对骨髓间充质干细胞（BM-MSC）生物学特性的影响。方法：应用体外培养传代的P4、P5、BM- MSC,分别采用剂量为50、75和100 mGy X射线照射(剂量率为12.5 mGy•min^-1),　检测不同剂量照射后BM-MSC生长、细胞周期与凋亡的变化。结果：与对照组比较,50、75和100 mGy照射后第5天BM-MSC生长进度明显加快（P<0.05）; 与同一时间对照组比较,50、75和100 mGy照射BM-MSC后,G₀/G₁期细胞百分率减少(P<0.05）,照射后72 h降至最低;S期细胞百分率在照射后48 和72 h逐渐明显增多(P<0.05）,以75 mGy照射后72 h,S期细胞百分率增多最明显(68.88%);而细胞凋亡的变化是50、75和100 mGy照射后24和48 h有增多趋势,照射后72 h凋亡细胞百分率有减少趋势。结论：LDR对BM-MSC有兴奋性效应。     

低剂量电离辐射对小鼠脾脏细胞凋亡的影响

目的：研究不同剂量 Ｘ 射线全身照射对小鼠脾脏细胞凋亡的影响。方法：采用透射电镜术定性及原位末端标记（ Ｔ Ｕ Ｎ Ｅ Ｌ）术半定量地观察了电离辐射对小鼠脾脏细胞凋亡影响的时程变化及量效关系。结果：透射电镜观察到２ Ｇｙ Ｘ 射线全身照射后脾脏出现较多典型的凋亡的淋巴细胞,００７５ Ｇｙ 照射后细胞超微结构无显著变化。 Ｔ Ｕ Ｎ Ｅ Ｌ 法观察到高剂量电离辐射使脾细胞凋亡增多,而低剂量电离辐射则使脾细胞凋亡减少,剂量效应关系曲线呈“ Ｊ”型。结论：不同剂量电离辐射对脾细胞凋亡的影响不同;低剂量电离辐射使脾脏细胞凋亡减少为辐射兴奋效应的一种表现。     

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.     

Effect of Cycloheximide on the Adaptive Response Induced by Low Dose Radiation

Human lymphocytes pre-exposed to 10 mGy or 50mGy of X-rays become less sensitive to subsequent large dose irradiation,exhibited lower rate of chromosome aberration than expected.This adaptive response could be inhibited by cycloheximide,a protein synthesis inhibitor for successive 2h period ranging from 0.5h before to 4h after the low dose exposure,indicating that the adaptive response was directly related with the protein synthesis.