Effect of growth rate of monolayer cells on survival after fractionated irradiation]

This study was performed to determine the effect of the growth rate of monolayer cells on survival following fractionated irradiation. HeLa and RMUG cells that had different radiosensitivities and growth rates (Do value: 2.3 vs 1.5 Gy, doubling time: 17 vs 46 hours) were irradiated with 2 Gy every day. The fractions surviving after fractionated irradiation were compared with those given single doses. The dose modifying factor for fractionated irradiation was larger in RMUG than HeLa: 1.7 and 1.2, respectively. Two clones from ADGU cells that had the same radiosensitivity but different growth rates were also given fractionated irradiation, but there was no difference in surviving fractions. When recovery following two split doses was determined in each type of cell, the results of the fractions surviving after fractionated irradiation were correlated only with recovery between split doses. These suggest that the growth rates of monolayer cells may not modify the fractions surviving after fractionated irradiation, and the monolayer cell system is not suitable for determining the effect of growth rates on survival following fractionated irradiation.     

Cytotoxicity of 125I-oestrogen decay in non-oestrogen receptor-expressing human breast cancer cells, MDA-231 and oestrogen receptor-expressing MCF-7 cells

PURPOSE: To compare the cytotoxicity of 125I-oestrogen (E-17alpha[125I]iodovinyl-11betamethoxyoestradiol or 125IVME2) decay accumulation in human breast adenocarcinoma cells that do not express oestrogen receptor (ER) (MDA-231 cells) with human breast adenocarcinoma cells that do express ER (MCF-7 cells). MATERIALS AND METHODS: MDA-231 cells were labelled with 125IVME2 or [125I]iododeoxyuridine (125IdU), frozen for decay accumulation, thawed and then plated for colony formation. gamma-irradiation survival was also determined. A whole-cell 3H-oestrogen-binding assay and a specific-binding assay were used to detect ER. RESULTS: No MDA-231 cell killing by accumulated 125IVME2 decays (up to 440 dpc) was observed but ER-positive MCF-7 cells were killed by 125IVME2 (D(o)=28 dpc). MDA-231 cells were not significantly more radioresistant to gamma-rays (D(o)=1.7Gy for MDA-231 cells; 1 Gy for MCF-7 cells) or to 125IdU decays (D(o)= 44dpc for MDA-231 cells; 30 dpc for MCF-7 cells). No ER were detected in MDA-231 cells. CONCLUSIONS: ER-negative cells, MDA-231, are not killed by 125IVME2 decay accumulation. It is speculated that without ER (required to translocate the 125IVME2 to its nuclear target), formation of the 125IVME2-ER-DNA oestrogen-response element (ERE) complex and subsequent specific irradiation of the DNA at the ERE cannot occur. These results support the hypothesis that the nuclear genome is a critical target for radiation-induced cell death.     

Cytotoxicity of 125 I-oestrogen decay in non-oestrogen receptor-expressing human breast cancer cells,MDA-231 and oestrogen receptor-expressing MCF-7 cells

Purpose : To compare the cytotoxicity of 125 I-oestrogen (E-17 α [ 125 I]iodovinyl-11 β methoxyoestradiol or 125 IVME2) decay accumulation in human breast adenocarcinoma cells that do not express oestrogen receptor (ER) (MDA-231 cells) with human breast adenocarcinoma cells that do express ER (MCF-7 cells). Materials and methods : MDA-231 cells were labelled with 125 IVME2 or [ 125 I]iododeoxyuridine (125 IdU), frozen for decay accumulation, thawed and then plated for colony formation. γ-irradiation survival was also determined. A whole-cell 3 H-oestrogen-binding assay and a specific-binding assay were used to detect ER. Results : No MDA-231 cell killing by accumulated 125 IVME2 decays (up to 440 dpc) was observed but ER-positive MCF-7 cells were killed by 125 IVME2 (D o =28 dpc). MDA-231 cells were not significantly more radioresistant to γ-rays (D o =1.7Gy for MDA-231 cells; 1 Gy for MCF-7 cells) or to 125 IdU decays (D o = 44dpc for MDA-231 cells; 30 dpc for MCF-7 cells). No ER were detected in MDA-231 cells. Conclusions : ER-negative cells, MDA-231, are not killed by 125 IVME2 decay accumulation. It is speculated that without ER (required to translocate the 125 IVME2 to its nuclear target), formation of the 125 IVME2-ER-DNA oestrogen-response element (ERE) complex and subsequent specific irradiation of the DNA at the ERE cannot occur. These results support the hypothesis that the nuclear genome is a critical target for radiation-induced cell death.     

P-gp糖蛋白及其编码的基因在受照射鼻 咽癌细胞株中的表达

目的模拟临床放射方法对人鼻咽鳞癌CNE细胞分次照射，检测照射前、后CNE细胞肿瘤多药耐药蛋白P-gp及其编码的基因MDR1的表达和功能。方法对人鼻咽鳞癌CNE细胞进行体外培养，待细胞进入指数生长期后模拟临床放疗方法进行X射线分割照射，2Gy／（d·f^-1），连续5d，总剂量10Gy。于照射前、照射后4、8、13、17和21d分别收取标本进行检测。利用RT-PCR、免疫细胞化学检测照射前、后人鼻咽鳞癌CNE细胞MDR1及P-gp的表达；MTT法检测其耐药指数（RI）的变化，评价P-gp的功能。结果人鼻咽鳞癌CNE细胞MDR1基因照射前呈弱表达，照后4d过度表达，8d到21d表达逐渐降低，与照射前比较，差异有统计学意义（P〈0．05）；其编码的蛋白产物P-gp照射前、照射后4和8d呈弱表达，13至21d表达增高，P-gp迟于MDR1基因高表达。MTT法检测耐药指数结果显示：照射前、照射后4和8d RI值均为1，13、17和21d RI分别增高为8、10和11．2，RI值变化的情况与P-gp的变化情况相一致。结论人鼻咽鳞癌CNE细胞照射前MDR1及P-gp呈弱表达，有原始的低度耐药性；照射后MDR1及功能性P-gp高表达并且持续一段时间。     

机械损伤加自体血清对VSMC生长及其自分泌PDGF的影响

目的探讨在机械损伤和自体血清刺激后,血管平滑肌细胞(VSMC)生长情况及其自分泌血小板衍生生长因子(PDGF)的量随时间的变化关系。方法模拟PTA术后体内环境建立体外SMC的细胞模型。ELISA法测定各上清液样本PDGF的浓度,MTT法检测各组细胞的生长和增殖情况。结果自体血清并部分自体机械损伤刺激后,实验组SMC的MTT值一直保持增加态势,至第5天达高峰,而对照组于第3天即达峰值;实验组PDGF的自分泌量逐渐升高,至第4、5天达峰值,比对照组峰值高出近一倍。结论兔VSMC在自体血清和机械损伤刺激下,生长增殖能力更强,自分泌的PDGF会逐渐升高,至第4~5天达高峰,该模型可大致模拟体内情况。     

Bone growth in the rabbit after irradiation.

The effect on bone growth of two locally given, different, unfractionated radiation doses (0.1 and 24 Gy) was tested in a rabbit litter aged 57 days. The effects on growth were registered with roentgen stereophotogrammetric length measurements for 75 days after irradiation. Growth of the right irradiated tibia was compared with the growth of the left non-irradiated tibia. After 7 to 9 days, 24 Gy had caused a linear fall in growth to about 15 per cent. After a period of complete cessation, a slight growth was registered. 0.1 Gy had no significant growth retarding effect.     

Studies in the small intestine of mice after fractionated neutron and x-ray irradiation

Several groups of mice received a whole-body irradiation with X-rays and neutrons. The survival and the number of crypts per intestinal circumference was measured after one-time, two-time, three-time, and four-time fractionation. The irradiation interval was 24 hours. Survival rate and number of crypts were compared to one another. There were discrepancies which could be explained by determining the right moments of examination. Thus it seems not recommendable to use the system of small intestine crypts for experiences with fractionated irradiations. The RBE values increased with the rising number of fractions. If Dn-Dl values were calculated, they increased on the one hand with the rising fractionation, on the other hand with the rising total dose. This effect was more marked after X-ray irradiation, less after neutron irradiation. This may be explained by the fact that, contrary to neutron irradiation, the recovery following to sublethal lesion by X-rays had not been exhausted.     

辐射后造血细胞对造血因子增殖反应性变化的研究

目的：深化造血细胞辐射损伤机理的认识，并为造血因子的合理应用提供理论指导。方法：应用ＭＴＴ法观察４种造血因子依赖细胞株于照射后不同时间对６种造血因子的增殖反应性变化。结果：造血因子依赖细胞株受照后对造血因子的增殖反应性降低，表现为细胞因子ＥＤ５０值的增加及最大增殖幅度的降低，照射剂量越大，反应性降低越明显，恢复所需时间越长。结论：增殖反应性降低可能是造血因子临床应用时剂量偏大的原因之一，并提示在造     

125I籽源连续照射诱导人乳腺癌细胞凋亡的研究

目的探讨125I籽源低剂量率γ射线持续照射诱导MCF-7人乳腺癌细胞凋亡过程中Bcl-2/Bax的变化情况.方法用9粒表面放射活度为27.75 MBq的6711型125I籽源连续照射MCF-7细胞72 h后,采用RT-PCR和Western blot法检测Bcl-2和Bax mRNA和蛋白表达.常规细胞流式法和Annexin V标记法直接检测MCF-7细胞凋亡率.结果 MCF-7细胞经125I籽源照射后较对照组Bcl-2 mRNA的表达降低,Bax mRNA的表达升高;Western blot检测Bcl-2/Bax比值,结果对照组为1.89±0.09,125I籽源照射组为0.62±0.08,两者差异有统计学意义(P＜0.05).常规细胞流式法检测照射组(n=10)和对照组(n=12)细胞凋亡率分别为(23.61±7.27)%和(2.81±1.68)%,P＜0.05.Annexin V标记法检测两组细胞早期凋亡率分别为(21.46±8.29)%和(1.94±1.38)%,P＜0.05.结论 125I籽源连续照射能够诱导Bcl-2/Bax比值的降低,促进MCF-7细胞的凋亡.     

siRNA表达载体对MCF-7细胞生长及其hTERT基因表达抑制的研究

目的构建人端粒酶反转录酶(hTERT)基因的RNA干扰(RNAi)表达载体,探讨该载体对人乳腺癌MCF-7细胞生长及hTERT基因表达的影响。方法设计针对hTERT基因的干扰靶序列,构建siRNA重组表达质粒pGenesil-hTERT,将该质粒酶切测序鉴定后,以脂质体转染MCF-7细胞,RT-PCR和Western blot技术分别检测hTERT基因及其蛋白的表达,MTT法观察转染后MCF-7细胞生长情况。结果酶切电泳和测序分析表明插入序列正确,重组质粒构建成功。该质粒转染MCF-7细胞后,hTERT基因mRNA和蛋白质的表达水平均显著降低,MCF-7细胞生长抑制。结论内源性短发夹状siRNA能有效抑制hTERT基因的表达,进而抑制乳腺癌MCF-7细胞的增殖生长,这也为肿瘤的基因治疗提供了实验依据。     

转化生长因子-β1在脑动脉瘤中的表达及意义

目的 探讨转化生长因子-β1（TGF-β1）在脑动脉瘤中的表达及意义。方法收集2011年3月~2014年3月我院收治的所有脑动脉瘤患者的动脉瘤标本,对患者的临床资料进行分析并采用免疫组化法检测组织标本中TGF-β1的表达情况。结果与对照组相比,观察组患者的脑动脉瘤标本经HE染色后显示出较为完整的结构形态。对照组TGF-β1总阳性表达率为28.57%,观察组为90.32%,明显高于对照组（P〈0.01）。结论 TGF-β1高表达可能在脑动脉瘤的发生发展过程中起到了重要的作用。     

分割照射对残留HepG2肝癌细胞侵袭迁移能力的影响

目的 研究分割照射后残留肝癌细胞侵袭迁移能力变化及其作用机制。方法 对HepG2细胞以2 Gy/次X射线进行分割照射,累积剂量达到20 Gy后继续培养30 d,检测残留肝癌细胞侵袭迁移能力的变化,Western blot法检测上皮细胞间充质转化（EMT）相关蛋白N-cadherin和Snail的表达。建立HepG2裸鼠皮下移植瘤模型并进行分割照射（2 Gy×10次）,观察肿瘤生长情况,肿瘤接种39 d（照射结束14 d）后检测辐照组和对照组裸鼠肿瘤肝转移情况及移植瘤内N-cadherin表达。结果 残留肝癌细胞侵袭迁移能力显著高于对照组（t=5.126、7.714,P<0.05）;残留肝癌细胞中N-cadherin和Snail表达显著增高（t=7.509、7.184,P<0.05）。在HepG2裸鼠皮下移植瘤模型中,辐照组裸鼠肿瘤质量和体积显著小于对照组（t=2.396、3.170,P<0.05）,辐照组皮下肿瘤肝转移灶数目、肿瘤组织中N-cadherin表达显著高于对照组（t=2.994,5.695,P<0.05）。结论 分割照射后残留肝癌细胞和组织的侵袭转移能力增强,EMT在其中发挥重要作用,该结果揭示了放疗后肿瘤复发转移的新机制。     

Changes in hemopoiesis of dying and surviving mice after fractionated irradiation and repeated bone marrow transplantation

Mice received doses of 3 Gy of 60Co-gamma rays total body irradiation at four-day intervals up to a total dose of 24 Gy. After each dose per fraction half of the animals were injected with 10(6) bone marrow cells. At four- and nine-day intervals evaluations were made of the blood count, bone marrow and spleen cellularities, and spleen mass. In animals subjected only to irradiation the damage of hemopoietic organs was becoming deeper until the end of observation; the majority of these mice died by nine days after the irradiation with the last dose per fraction (by 37 days of the experiment). The authors consider anemia as the main cause of their death. All of the mice that were given bone marrow injections survived; nine days after the last dose of irradiation the mean cellularities of their bone marrows and spleens were 76.8% and 112.3% of the unirradiated controls respectively. In general, regeneration of erythropoiesis was quite successful, the number of thrombocytes was positively influenced, and the number of leukocytes nearly unchanged in bone marrow recipients when compared with the only irradiated mice. We observed two periods of maximum and one of minimum bone marrow and spleen regeneration, which were not synchronized. These results deny an unrepairable damage to the hemopoietic microenvironment in conditions of our experiment. This paper follows up with our preceding work [10] describing results of an experiment which ended on day 24.     

Volume and dose-response effects for severe symptomatic pneumonitis after fractionated irradiation of canine lung

PURPOSE: To study the dose-related incidence of severe symptomatic pneumonitis following fractionated irradiation applied to three different volumes of lung in normal beagle dogs. MATERIALS AND METHODS: A three-dimensional treatment planning system was used to design mediastinal fields of increasing width to irradiate 33%, 67% or 100% of both lungs combined in 128 normal beagle dogs. Total doses, ranging from 27 to 72 Gy, were delivered in 1.5 Gy fractions over 6 weeks. RESULTS: No dogs irradiated to 33% of their total lung volume developed severe symptomatic pneumonitis. In the 67% volume group, logistic fit of the data showed a dose-response curve with a 50% probability of developing severe symptomatic pneumonitis (ED50) after a total dose of 56.0 Gy (52.2-66.0 Gy, 95% confidence interval, CI). The more clinically relevant ED5 for the first 6 months after irradiation of 67% of the lung was 48.1 Gy (18.5-52.0 Gy, 95% CI). The ED50 and ED5 values after irradiation of the whole lung (100%) were 44.1 Gy (41.2-53.5Gy, 95% CI) and 39.1 Gy (8.8-41.8 Gy, 95% CI) respectively. CONCLUSION: Severe symptomatic pneumonitis proved to be a very informative volume-effect endpoint, clearly demonstrating that irradiated lung volume is a critical parameter to be considered in assigning thoracic radiotherapy treatment parameters. Volume effects in lung are dependent on the compensatory capacity of the nonirradiated lung. Underlying pathophysiology of irradiated tissue, as well as decreased compensatory capacity of nonirradiated tissue may have a strong effect on the dose-volume response.