發(fā)布時間：2018-08-05 20:46

【摘要】：目的：已知乏氧可以直接通過氧剝奪或間接影響細胞生理功能而導致輻射抗性。為了研究乏氧細胞對低線性能量傳遞X射線以及高線性能量傳遞碳離子線的放射敏感性,以及慢性氧缺乏下細胞周期分布的改變對細胞存活的影響。X線和醫(yī)用高能碳離子線對不同乏氧狀況下中國倉鼠卵巢細胞CHO-Kl細胞的放射效應進行研究。相應的細胞克隆存活和細胞周期分布進行了測量。 材料與方法：,在標準條件下培養(yǎng)的CHO-K1細胞,進行有氧(空氣),乏氧(0.5%O2,94.5%N2,5%CO2)或無氧(95%N2,5%CO2)狀況下的實驗。為了達到急性無氧或乏氧,5個特殊設計的乏氧照射盒串接到氣瓶,相應的混合氣體(95%N2,5%CO2或0.5%的O2,94.5%的氮氣,5%C02)以200毫升/分鐘流量進行氣體置換2小時。在達到急性無氧或乏氧后,將乏氧照射盒密閉并保持氣密性24小時,盒內(nèi)細胞即達慢性無氧或乏氧狀態(tài)。而將乏氧照射盒內(nèi)的細胞重新暴露在空氣中一定時間,即可進行再氧合實驗。用250kVp的X射線及碳離子射線進行照射。碳離子的平均線性能量傳遞為103keV/u m,用1cm的擴展Bragg峰碳離子對CHO-K1細胞進行照射,進行克隆形成實驗。在無氧、乏氧情況下及慢性無氧或乏氧后再氧合情況下的細胞周期變化進行檢測。 結(jié)果：從不同氧狀態(tài)下的存活曲線,我們可以看到,慢性乏氧的細胞和急性乏氧相比具有非常相似的放射敏感性。而慢性無氧的細胞和急性無氧相比具有相對更高的放射敏感性；慢性無氧再氧合1小時的細胞也顯示了相對于有氧細胞的放射敏感性增加；這在X線和碳離子線照射情況下均有發(fā)現(xiàn)。相應細胞周期分布的檢測顯示乏氧狀態(tài)下細胞周期分布相當均勻,而慢性乏氧再氧合后的研究也顯示了細胞周期隨時間的均一性變化,與有氧細胞相比無明顯區(qū)別。而再氧合下細胞周期的均一分布也導致了再氧合1小時與24小時的幾乎相同的存活。而慢性無氧后CHO-K1細胞明顯阻滯于G1期,而S期細胞比例明顯下降,甚至缺乏；再氧合后的細胞周期分布在最初12小時變化非�？�,并且在15-24小時時與有氧狀態(tài)下細胞周期分布是可比的。同時,慢性無氧再氧合0,1小時的CHO-K1細胞和慢性無氧再氧合15小時下的細胞相比顯示了對X線增加的放射敏感性。 結(jié)論：在X線和碳離子照射實驗中,和急性無氧狀態(tài)下相比,慢性無氧狀況下細胞放射敏感性的增加及OER的減小,是由于慢性無氧引起的細胞周期G1阻滯及S期缺乏所引起的。和X線相比,碳離子顯示了更為有效的殺傷,特別是對乏氧和無氧狀態(tài)下的細胞。但是,和X線相比,本實驗并未觀察到碳離子照射可以減小慢性無氧所引起的細胞周期改變對存活的影響。
[Abstract]:Objective: it is known that hypoxia can directly or indirectly affect the physiological function of cells and lead to radiation resistance. In order to study the radiosensitivity of hypoxic cells to low linear energy transfer X-rays and high linear energy transfer carbon ion lines, The effects of the changes of cell cycle distribution on cell survival under chronic oxygen deficiency. X ray and medical high energy carbon ion line were used to study the radiative effects of Chinese hamster ovarian CHO-Kl cells under different hypoxia conditions. Cell clone survival and cell cycle distribution were measured. Materials and methods: CHO-K1 cells cultured under standard conditions were tested with oxygen (air), hypoxia (0.5) and oxygen (0.5) or anaerobic (95N _ 2 ~ (5) CO _ 2). In order to achieve acute anoxia or hypoxia, five specially designed hypoxic irradiating boxes were connected to gas cylinders, and the corresponding mixture gas (95N2CO _ 2 or 0.5% O _ 2N _ 2 94.5% nitrogen, 52) was replaced with 200 ml / min flow rate for 2 hours. After the acute hypoxia or hypoxia was reached, the hypoxia irradiation box was sealed and kept airtight for 24 hours, and the cells in the box reached chronic hypoxia or hypoxia. The reoxygenation experiment can be carried out by reexposing the cells in the hypoxia irradiation box to air for a certain time. 250kVp X ray and carbon ion ray were used to irradiate. The average linear energy of the carbon ions was transferred to 103keV/u m. The CHO-K1 cells were irradiated with the extended Bragg peak carbon ions of 1cm and cloned into CHO-K1 cells. Cell cycle changes were detected in anaerobic, hypoxic and chronic hypoxic or post-hypoxia reoxygenation conditions. Results: from the survival curves of different oxygen states, we can see that chronic hypoxia cells have very similar radiosensitivity to acute hypoxia. The cells with chronic hypoxia had higher radiosensitivity than those with acute hypoxia, and cells with 1 hour of chronic anaerobic reoxygenation also showed higher radiosensitivity to aerobic cells. This is found in both X-ray and C-ray irradiation. The detection of cell cycle distribution showed that the cell cycle distribution was quite uniform in hypoxic state, and the study of chronic hypoxia reoxygenation showed that the cell cycle changed homogeneously with time, and there was no significant difference between the cell cycle and aerobic cells. The homogeneous distribution of cell cycle under reoxygenation also resulted in almost the same survival at 1 hour and 24 h after reoxygenation. However, after chronic hypoxia, CHO-K1 cells were significantly blocked in G1 phase, while the proportion of S phase cells decreased significantly, and the cell cycle distribution after reoxygenation changed very rapidly at the first 12 hours. And the cell cycle distribution at 15-24 hours was comparable to that at aerobic state. At the same time, the radiosensitivity of CHO-K1 cells after 1 hour of chronic anaerobic reoxygenation and 15 hours of chronic anaerobic reoxygenation showed increased radiosensitivity to X-ray. Conclusion: the increase of radiosensitivity and the decrease of OER in chronic hypoxia are due to cell cycle G1 arrest and S phase deficiency. Compared with X-ray, carbon ion showed more effective killing, especially to cells in hypoxic and anoxic state. However, compared with X ray, it was not observed that carbon ion irradiation could reduce the effect of chronic hypoxia on cell cycle survival.
【學位授予單位】：復旦大學
【學位級別】：博士
【學位授予年份】：2012
【分類號】：R730.55

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相關期刊論文 前2條

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本文編號：2166978