高温下极低频电磁场暴露对果蝇hsp22和hsp26基因影响的研究

目的：探讨在高温（35℃）条件下,极低频电磁场（ extremely low frequency electromagnetic fields ,ELF-EMF）对雌雄黑腹果蝇hsp22和hsp26基因表达水平的影响。方法在25、27．5、30、32．5、35℃下,1日龄雌、雄黑腹果蝇在50 Hz、3 mT ELF-EMF暴露2 h,测定其死亡率、运动能力和hsp22、hsp26表达水平;在25和35℃下,1日龄雌、雄黑腹果蝇在50 Hz、3 mT ELF-EMF暴露2、4、8、24 h,测定其hsp22、hsp26表达水平。结果在25、27．5、30、32．5、35℃下暴露2 h,温度变化对果蝇的死亡率、运动能力和hsp22、hsp26表达水平有极显著影响（P＜0．01）,ELF-EMF对hsp22、hsp26表达水平无显著影响（ P＞0．05）;在25和35℃下分别暴露2、4、8、24 h,性别、温度、ELF-EMF暴露和暴露时间对hsp22、hsp26的表达水平有极显著影响,其中,温度是主要的影响因素,且若干因素间有交互作用。结论 ELF-EMF可影响果蝇hsp22、hsp26的表达,且ELF-EMF可能具有降低因高温环境所致负面影响的作用,提高果蝇对高温环境的耐受能力,缓解高温环境对果蝇的损伤效应。     

在Fas和放线菌素D诱导Bel-7402细胞凋亡中激活的caspase-8调节Bcl-2表达

目的探讨在Fas和放线菌素D(actinomycin D,AD)诱导Bel-7402细胞的凋亡过程中,激活的caspase-8是否调节Bcl-2表达。方法取对数生长的细胞随机分组实验:对照组、Fas组、Fas-AD组、caspase-8抑制剂Ac-IEFD-cho组。在Bel-7402细胞中添加或不添加caspase-8的抑制剂(Ac-IEFD-cho),然后加入Fas和AD。通过电镜观察细胞的超微结构,通过Western-blot和RT-PCR检测caspase-8和Bcl-2表达。结果与对照组比较,在Fas和放线菌素D作用下,细胞凋亡的形态结构清晰可见,激活的caspase-8表达增加,同时Bcl-2表达降低;然而在Ac-IEFD-cho抑制剂作用下,激活的caspase-8表达减少,Bcl-2表达增加。结论在Fas和放线菌素D诱导Bel-7402细胞的凋亡过程中,激活的caspase-8能调节Bcl-2表达。     

~(252)Cf裂变中子源在组织等效模体中的中子和γ辐射剂量分布的计算

目的　计算2 5 2 Cf裂变中子源的中子和γ辐射在组织等效模体内的剂量分布 ,为使用2 5 2 Cf裂变中子源进行中子放疗提供有用的剂量学参数。方法　建立2 5 2 Cf源和组织等效模体的三维几何计算模型 ,利用蒙特卡罗方法进行中子和γ辐射联合输运计算。结果　计算了两种医用2 5 2 Cf裂变中子源在水、血液、肌肉、皮肤、骨骼和肺组织等效材料构成的模体中距源不同距离点处的中子和γ辐射吸收剂量。结论　蒙特卡罗计算结果与文献数据以及使用双电离室实验测量的结果符合得较好。对2 5 2 Cf裂变中子源在 5种组织材料构成的模体中中子和γ辐射的剂量分布进行了比较 ,使用水作为组织等效材料对2 5 2 Cf裂变中子源在以肌肉、血液和皮肤构成的局部组织内的剂量分布进行模拟计算 ,可取得比较可靠的结果。     

Cellular effects of extremely low frequency (ELF) electromagnetic fields

Purpose: The major areas of research that have characterised investigation of the impact of extremely low frequency (ELF) electromagnetic fields on living systems in the past 50 years are discussed. In particular, selected studies examining the role of these fields in cancer, their effects on immune and nerve cells, and the positive influence of these ELF fields on bone and nerve cells, wound healing and ischemia/reperfusion injury are explored.

Conclusions: The literature indicates that there is still no general agreement on the exact biological detrimental effects of ELF fields, on the physical mechanisms that may be behind these effects or on the extent to which these effects may be harmful to humans. Nonetheless, the majority of the in vitro experimental results indicate that ELF fields induce numerous types of changes in cells. Whether or not the perturbations observed at the cellular level can be directly extrapolated to negative effects in humans is still unknown. However, the myriad of effects that ELF fields have on biological systems should not be ignored when evaluating risk to humans from these fields and, consequently, in passing appropriate legislation to safeguard both the general public and professionally-exposed workers. With regard to the positive effects of these fields, the possibility of testing further their efficacy in therapeutic protocols should also not be overlooked.     

极低频磁场联合X线对人肝癌细胞株BEL-7402作用的机制研究

目的 研究极低频磁场联合X线对人肝癌细胞株BEL-7402的作用机制。方法 人肝癌细胞株BEL-7402经0、2、4、6、8、10 Gy X线照射后,用极低频磁场处理(100 Hz、0.7 mT、30 min、3 d)后,利用扫描电镜作形态观察,流式细胞仪、基因芯片研究细胞凋亡机制。结果 扫描电镜形态显示,极低频磁场联合X线组肝癌细胞株BEL-7402发生凋亡改变。流式细胞仪观察结果显示,当X线剂量是2、4、6、8、10 Gy, 极低频磁场联合X线凋亡率为10.0%、14.5%、4.3%、5.1%、7.1%,X线组凋亡率是0.1%、8.10%、0.1%、0.4%、 2.2% (P<0.05)。基因芯片结果显示,极低频磁场联合X线组共有1465条出现上调,1108条出现下调。其中比值≥2倍的基因共有336条,上调262条,下调74条。与凋亡相关基因共110条,上调基因71条,下调基因39条。涉及CDC25、CHK1、ATM、p38、PTEN、p53、G₁/S、Fas、G₂/M、Cell Cycle、Apoptosis、Caspase基因通路中的基因。极低频磁场加X线组差异表达结果中有13条同时出现在极低频磁场组。42条同时出现在X线组。结论 极低频磁场与X线通过不同的基因通路影响细胞凋亡。极低频磁场与X线对人肝癌细胞株BEL-7402凋亡有协同作用。     

低频电磁场对健康飞行人员甲皱微循环的影响

目的 观测低频脉冲电磁场对飞行人员甲皱微循环的影响,为在临床上用于增强飞行人员身体素质,改善飞行疲劳,提高防病抗病能力提供理论根据. 方法 选择健康飞行人员50名,采用120 MT低频脉冲电磁场作用于受试者左肘关节屈侧20 min,于作用前和作用后即刻各观测甲皱微循环1次. 结果 低频电磁场作用后,有82%的人微血管数目无变化或增加.微血管形态以扩张为主,作用后微血管扩张人数占78%.微血管口径较作用前增大明显(t=2.301～3.436,P<0.05),差异有统计学意义.袢长较作用前明显增长(t=13.060,P<0.01),差异有统计学意义.微血管的血流速度作用后明显加快,血流流态为线流或线粒流两个级别的人数明显增多(X2=18.136,P<0.01),差异有统计学意义. 结论 低频脉冲电磁场作用于机体特定部位后可减少飞行人员微循环变异,改善其微循环状态.     

低强度脉冲电磁场对兔凝血酶原时间和活化部分凝血活酶时间的影响

目的探讨低强度脉冲电磁场对兔血液凝血时间的影响。方法健康雌性新西兰大耳白兔30只,随机分为3组,正常组（A组）用常规饲料喂养,模型组（B组）和磁场组（C组）用高胆固醇饲料喂养,C组暴露饲养于低强度脉冲电磁场环境中。饲养7W后,采血用比浊法检测凝血酶原时间（PT）和活化部分凝血活酶时间（APTT）。结果比较各组胛和APTF,B组低于A组（P〈0．01）;C组高于B组（P〈0．01）;A组和C组差异无统计学意义。结论低强度脉冲电磁场可以明显延长盯和APTT,提高血液流动性,为心血管疾病预防提供新思路。     

Brain DNA damage and 70-kDa heat shock protein expression in CD1 mice exposed to extremely low frequency magnetic fields

Purpose:?The question of whether exposure to extremely low frequency magnetic fields (ELF-MF), may contribute to cerebral cancer and neurodegeneration is of current interest. In this study we investigated whether exposure to ELF-MF (50 Hz-1 mT) harms cerebral DNA and induces expression of 70-kDa heat shock protein (hsp70).

Materials and methods:?CD1 mice were exposed to a MF (50 Hz-1 mT) for 1 or 7 days (15 h/day) and sacrificed either at the end of exposure or after 24?h. Unexposed and sham-exposed mice were used as controls. Mouse brains were dissected into cerebral cortex-striatum, hippocampus and cerebellum to evaluate primary DNA damage and hsp70 gene expression. Food intake, weight gain, and motor activity were also evaluated.

Results:?An increase in primary DNA damage was detected in all cerebral areas of the exposed mice sacrificed at the end of exposure, as compared to controls. DNA damage, as can be evaluated by the comet assay, appeared to be repaired in mice sacrificed 24?h after a 7-day exposure. Neither a short (15?h) nor long (7 days) MF-exposure induced hsp70 expression, metabolic and behavioural changes.

Conclusions:?These results indicate that in?vivo ELF-MF induce reversible brain DNA damage while they do not elicit the stress response.     

Effects of single- and hybrid-frequency extremely low-frequency electromagnetic field stimulations on long-term potentiation in the hippocampal Schaffer collateral pathway

Abstract

Purpose: To study the different effects of single- and hybrid-frequency magnetic fields on long-term potentiation (LTP) in synaptic plasticity.

Materials and methods: Based on the online electromagnetic field stimulation system and field excitatory postsynaptic potentials (fEPSPs) recording system, we applied four different single- and hybrid-frequency magnetic fields with an intensity of 1?mT to the Schaffer collateral (CA1) pathway of rat hippocampal slices in vitro.

Results: The amplitude of fEPSPs decreased significantly under both single- and hybrid-frequency magnetic stimulation. Lower single-frequency magnetic stimulation on LTP had a greater regulating effect, while the regulating effect among four different hybrid-frequency extremely low-frequency electromagnetic fields (ELF-EMFs) stimulations on LTP showed no significant differences.

Conclusion: Single-frequency magnetic stimulation produces more significant regulatory effects, and the lower the frequency, the more significant the regulatory effect. The effect of hybrid-frequency magnetic stimulation in each group was similar, and there was no significant difference between each group. The 15-Hz single-frequency magnetic stimulation group showed the most significant regulatory effect, but once it was mixed with other higher frequency magnetic stimulation, its regulation effect was significantly weakened.     

50 Hz 1 mT脉冲电磁场对脐带间充质干细胞免疫调节能力的影响及其安全性评价

目的探讨50 Hz 1 mT脉冲电磁场（PEMF）对脐带间充质干细胞（MSC）免疫调节能力的影响及其安全性。方法采用50 Hz 1 mT PEMF辐照脐带MSC,MTT法检测辐照后细胞活性的变化;实时荧光定量PCR法检测脐带MSC的环氧合酶2（COX2）、IL-10、吲哚胺-2,3-双加氧酶（IDO）、肝细胞生长因子（HGF）和转化生长因子β（TGF-β）等基因mRNA表达水平的改变;流式细胞仪检测PEMF对脐带MSC活性氧（ROS）水平、细胞凋亡和细胞周期的影响;单细胞凝胶电泳分析脐带MSC DNA损伤的情况。采用SPSS19.0软件,对各组间数据进行独立样本t检验分析。结果50 Hz 1 mT PEMF辐照可增强脐带MSC的细胞活性,其中每天辐照4 h组变化最为明显,差异有统计学意义（t=3.505,P < 0.05）。PEMF辐照可促进COX2、HGF、IDO和TGF-β等免疫调节因子mRNA的表达,但变化不明显,差异无统计学意义（t=0.982~2.376,均P>0.05）,对于干扰素γ（IFN-γ）激活的MSC,PEMF辐照可显著上调COX2、HGF、IDO和TGF-β的mRNA表达水平,差异有统计学意义（t=2.436~3.747,均P < 0.05）。50 Hz 1 mT PEMF辐照对脐带MSC的ROS水平、DNA损伤及细胞凋亡率、细胞周期无显著影响。结论对于IFN-γ激活的MSC,50 Hz 1 mT PEMF可显著上调COX2、HGF、IDO和TGF-β的mRNA表达水平,从而增强脐带MSC的免疫调节能力。50 Hz 1 mT PEMF对脐带MSC的ROS水平、细胞凋亡及DNA损伤无明显影响,此参数下的PEMF辐照对脐带MSC是安全的。     

Extremely low frequency magnetic fields cause oxidative DNA damage in rats

Purpose: To detect the genotoxic effects of extremely low frequency (ELF) -magnetic fields (MF) on oxidative DNA base modifications [8-hydroxyguanine (8-OH-Gua), 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapyGua) and 4,6-diamino-5-formamidopyrimidine (FapyAde)] in rat leucocytes, measured following exposure to ELF-MF.

Materials and methods: After exposure to ELF-MF (50 Hz, 100 and 500 μT, for 2 hours/day during 10 months), DNA was extracted, and measurement of DNA lesions was achieved by gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS).

Results: Levels of FapyAde, FapyGua and 8OHdG in DNA were increased by both 100 μT and 500 μT ELF-MF as compared to a cage-control and a sham group; however, statistical significance was observed only in the group exposed to 100 μT.

Conclusion: This is the first study to report that ELF-MF exposure generates oxidatively induced DNA base modifications which are mutagenic in mammalian cells, such as FapyGua, FapyAde and 8-OH-Gua, in vivo. This may explain previous studies showing DNA damage and genomic instability. These findings support the hypothesis that chronic exposure to 50-Hz MF may be potentially genotoxic. However, the intensity of ELF-MF has an important influence on the extent of DNA damage.