Resazurin assay of radiation response in cultured cells

We describe use of resazurin reduction for measurement of cell response to irradiation as a simple and non-destructive assay that complements the conventional colony forming assay and can readily be applied to both adherent and non-adherent cell cultures. The resazurin method yields data comparable with the colony forming assay as well as to assay of DNA synthesis (BrdU incorporation), giving an OER (oxygen enhancement ratio) of 2.5 at 60% isoeffect level versus 3.1 for the colony forming assay. Intraday and interday precisions for the resazurin assay were 4.1% and 5.2%, respectively.     

Respiration-induced oxygen gradients in cultured mammalian cells

The effect of cell respiration on the availability of intracellular oxygen was investigated by comparing the radiosensitivities of respiring and non-respiring cells over a range of oxygen tensions. Monolayers of Chinese hamster V79 fibroblasts on glass Petri dishes were irradiated at respiration-inhibiting (4 degrees C) and normal (37 degrees C) cell-culturing temperatures. Desired extracellular oxygen concentrations were achieved by aspirating the culture medium above the cells prior to irradiation, leaving a residual thin film which prevented drying of the cells while allowing rapid equilibration with the overlying gas. Measurement of clonogenic survival revealed that, at equivalent extracellular oxygen concentrations, the cells irradiated at 37 degrees C were less radiosensitive than those irradiated at 4 degrees C. The difference in respiring and non-respiring cell radiosensitivity was dependent on cell shape, and decreased when the cells attached to the Petri dish surface were allowed to assume a flatter configuration. These results imply that at low extracellular oxygen tensions the oxygenation of critical cellular radiation target(s) is dependent on respiration and diffusion distance, as would be expected if oxygen gradients induced by respiration exist within and immediately around actively metabolizing cells.     

Biological effects of static gradient magnetic field on cultured mammalian cells and combined effects with 60Co gamma-rays]

The biological effects of a static gradient magnetic field and its combined effects with ionizing radiation on FM3A cultured cells were investigated. The magnetic strength of the center of the field was 5.8 x 10(-2) T esla, the mean gradient of the magnetic filed was 0.6 T esla/m. The magnetic field influenced cell cycle. The relative amount of cultured cells in G1 phase decreased for eight hours after exposure. The growth rate of the cells was slowed by about 5%. Following exposure to the magnetic field, the survival rate of cells decreased to about 20% less than that of the non-exposed control. The combined effect of 60Co irradiation with exposure to the magnetic field showed a greater effect than a simple additive one. The combined effect was influenced by the interval between 60Co irradiation and exposure to the magnetic field. The biological effects of the magnetic field may be related to age-dependent cellular damage in the cell cycle, blockage of cell progression in the cell cycle, and increased repair from radiation damage.     

The effect of ethanol on the radiation response of CHO-K1 cells

The radiobiological response of CHO-K1 cells treated with ethanol is described. Both radioprotective and radiosensitising effects were found, depending on the duration of exposure before irradiation and the number of cells exposed. In spite of effects of ethanol on the shoulder of the primary survival curve, split-dose recovery was not affected. The radiobiological effect of alcohols is normally attributed either to radical scavenging or to oxidation. The findings presented here do not support either of these mechanisms.     

射频辐射对哺乳动物体细胞遗传学效应的Meta分析

目的 探讨射频辐射对哺乳动物体细胞的遗传学影响。方法 采用Meta分析方法,对国内外1991—2009年关于哺乳动物体细胞遗传学损伤与射频辐射暴露关系的研究文献共计46篇进行综合定量分析。结果 射频辐射暴露后,辐射组与对照组彗尾尾长的加权均数差(WMD)及95%CI为1.03(0.74, 1.31),尾距为0.10 (0.04, 0.16);和对照组比较,2000 MHz以下的射频辐射组染色体畸变RR及95%CI为1.21(0.68,2.13),大于2000 MHz组为1.76(1.05,2.97);射频辐射与微核发生的合并RR及95%CI为1.39(1.18,1.64);射频辐射组与对照组SCE发生数目的WMD及95%CI为0.40(-0.33,1.14)。结论 射频辐射暴露一定程度上会加重哺乳动物体细胞DNA损伤,增加微核发生率;2000 MHz以上的射频辐射可能会引起染色体畸变率的上升,低于2000 MHz的射频辐射对染色体畸变发生无显著影响;射频辐射暴露对哺乳动物体细胞姐妹染色单体交换的发生无显著影响。     

微波辐射对培养的hTERT-RPE1细胞的应激损伤

目的：观察2450MHz微波辐射对培养的hTERT—BPEl细胞的应激损伤。方法：体外培养的人视网膜色素上皮细胞系细胞，分别在强度为10、20、30mW／cm2的微波下辐射1h，辐射后，用光学显微镜和透射电镜观察各组细胞的形态及变化；台盼蓝染色检测细胞存活率；测定细胞内抗氧化物酶SOD和GSH—Px的活性和脂质过氧化产物MDA的含量；另外，继续培养各组细胞，观察微波辐射对细胞增殖的影响。结果：微波辐射后，细胞存活率、细胞内抗氧化物酶SOD、GSH—Px活性与对照组相比显著降低；而过氧化产物MDA含量与对照组相比显著升高，其降低或升高的幅度与微波辐射的强度的大小有关。结论：2450MHz微波辐射可引起培养的hERT—BPEl细胞的应激损伤。     

E838对辐射诱导哺乳动物细胞恶性转化的影响

目的 研究抗放药物E838对辐射诱导哺乳动物细胞恶性转化的影响。方法 用不同剂量的^137Csγ射线照射培养的CHO和CHL细胞,比较在有或没有E838的情况下,其对细胞集落形成率以及转化率的影响。结果 在3Gy照射剂量下,CHO细胞加药1μg/ml处理组集落形成率显著高于不加药组（P＜0．05）,而转化率加药组比不加药组低且有统计学意义（P＜0．01）。CHL细胞在此范围内变化亦有同样的趋势,但结果无统计学意义（P＞0．05）。结论 E838在浓度范围内对辐射诱导哺乳动物细胞转化有一定的抑制作用。     

Adaptive response and the influence of ageing: effects of low-dose irradiation on cell growth of cultured glial cells

Purpose : To examine the molecular mechanism of radiation adaptive response (RAR) for the growth of cultured glial cells and to investigate the influence of ageing on the response. Materials and methods : Glial cells were cultured from young and older rats (1 and 24 months). RAR for the growth of glial cells conditioned with a low dose of X-rays and subsequently exposed to a high dose of X-rays was examined for cell number and BrdU incorporation. Involvement of the subcellular signalling pathway factors in RAR was investigated using their inhibitors, activators, and mutated and knockout glial cells. Results : RAR was observed in cells cultured from young rats but was not in cells from older animals. The inhibitors of protein kinase C (PKC) and DNA-dependent protein kinase (DNA-PK) or phosphatidylinositol 3-kinase (P13K) suppressed RAR. The activators of PKC instead of low-dose irradiation also caused RAR. Moreover, glial cells cultured from severe combined immunodeficiency (scid) mice (CB-17 scid) and ataxiatelangiectasia mutated (Atm) knockout mice showed no RAR. Conclusion : The results indicated that PKC, ATM, DNAPK and/or P13K were involved in RAR for growth and BrdU incorporation of cultured glial cells and RAR decreased with ageing.     

Adaptive response and the influence of ageing: effects of low-dose irradiation on cell growth of cultured glial cells

PURPOSE: To examine the molecular mechanism of radiation adaptive response (RAR) for the growth of cultured glial cells and to investigate the influence of ageing on the response. MATERIALS AND METHODS: Glial cells were cultured from young and older rats (1 and 24 months). RAR for the growth of glial cells conditioned with a low dose of X-rays and subsequently exposed to a high dose of X-rays was examined for cell number and BrdU incorporation. Involvement of the subcellular signalling pathway factors in RAR was investigated using their inhibitors, activators, and mutated and knockout glial cells. RESULTS: RAR was observed in cells cultured from young rats but was not in cells from older animals. The inhibitors of protein kinase C (PKC) and DNA-dependent protein kinase (DNA-PK) or phosphatidylinositol 3-kinase (PI3K) suppressed RAR. The activators of PKC instead of low-dose irradiation also caused RAR. Moreover, glial cells cultured from severe combined immunodeficiency (scid) mice (CB-17 scid) and ataxia-telangiectasia mutated (Atm) knockout mice showed no RAR. CONCLUSION: The results indicated that PKC, ATM, DNAPK and/or PI3K were involved in RAR for growth and BrdU incorporation of cultured glial cells and RAR decreased with ageing.