极低频率（ELF）磁场对细胞生长周期分布谱的影响及其机理的计算机模拟分析

测定在各种温度条件下和在ＥＬＦ（极低频率）磁场作用下细胞生长周期分布谱的变化。实验结果表明温度不仅能使周期分布谱的离散性发生改变,而且也能使谱的峰值产生位移,而ＥＬＦ磁场只能使周期分布谱的离散性发生变化,对谱的峰值没有显著影响。这一差异是由于温度和ＥＬＦ磁场对细胞生长产生影响的机理不同。用计算机模拟不同机理对细胞生长周期分布谱的影响与我们早先提出的机理相吻合,即温度影响细胞内各种生长因子、生物离子的活性,而ＥＬＦ磁场则可能通过对细胞膜的影响使细胞内的细胞生长必不可少的生物离子的浓度发生变化。     

极低频率（ELF）磁场对细胞生长周期分布谱的影响及其机理的计算机模拟分析

测定在各种温度条件下和在ＥＬＦ（极低频率）磁场作用下细胞生长周期分布谱的变化。实验结果表明温度不仅能使周期分布谱的离散性发生改变,而且也能使谱的峰值产生位移,而ＥＬＦ磁场只能使周期分布谱的离散性发生变化,对谱的峰值没有显著影响。这一差异是由于温度和ＥＬＦ磁场对细胞生长产生影响的机理不同。用计算模拟不同机理对细胞生长周期分布谱的影响与我们早先提出的机理相吻合,即温度影响细胞内各种生长因子、生物离子的     

一定参数的磁场在不同生物层次上抑制恶性肿瘤生长

目的 :在不同生物层次上观测一定参数的磁场抑制恶性肿瘤生长。方法 :用脉冲梯度磁场 (峰值磁场 0 .6- 2 .0T ,磁场梯度 1 0 - 1 0 0T·M - 1 ,脉冲宽度 2 0 - 2 0 0ms,重复频率 0 .1 6- 1 .34Hz)治疗白鼠 ,在不同生物层次上 ,例如生物活体、器官、组织、细胞和大分子 ,能抑制鼠恶性肿瘤生长。结果 :上述磁场诱导癌细胞凋亡和阻塞供应肿瘤的新生血管。磁场对运动离子的洛仑兹力 ,使它们束缚在拉莫尔 (Larmor)半径以内 ,会影响正负带电离子对细胞膜和核膜的渗透能力 ,甚至在细胞膜和核膜上形成空洞。结论 :由于这一磁场抑制癌瘤生长 ,所以它能成为一种治疗癌瘤的新方法。     

极低频磁场对人乳腺癌细胞蛋白质表达谱的影响

极低频磁场(ELF MF)被国际癌症研究中心列为可疑致癌物, 但其诱发肿瘤的具体机制并不清楚. 为此, 采用蛋白质组技术研究人乳腺癌细胞MCF7受ELF MF辐照后蛋白质表达谱的变化, 以探索确定该细胞的极低频磁场反应蛋白质. 在将MCF7细胞暴露于50 Hz, 0.4 mT正弦极低频磁场中24 h后, 直接抽提蛋白, 进行双向凝胶电泳. 凝胶经银染后, 使用PDQuest软件分析假辐照组与磁场辐照组间差异表达蛋白质斑点. 结果显示, 与假辐照组相比, 磁场辐照组中有6个蛋白质斑点的表达量发生显著改变(至少5倍的增加和减少), 同时, 在磁场辐照组中有19个蛋白点消失和19个新蛋白点出现. 通过搜索SWISS-PROT蛋白数据库, 对差异蛋白的类别和功能进行了初步推测. 在此基础上, 进一步选择3个差异表达蛋白斑点, 经胶内酶解后, 进行串联质谱分析, 分别鉴定为RNA结合蛋白调节亚基、 蛋白酶体β亚基7型前体和翻译调控肿瘤蛋白. 结果表明, 50 Hz, 0.4 mT极低频磁场辐照24 h改变了MCF7细胞内多种蛋白的表达水平, 影响环节涉及基因转录、蛋白翻译、蛋白代谢、功能蛋白相互作用等多个层面, 说明极低频磁场可能作为一种环境应激因素改变细胞的正常生理功能.     

极低频磁场对人肝癌细胞生长、代谢及细胞周期的影响

目的研究一定参数的极低频磁场对人肝癌细胞(SK-HEP-1)在诸多方面的影响。方法在整个SK-HEP-1细胞的培养周期中用50Hz,20mT的极低频磁场对其进行作用,并检测作用后细胞的增殖活性、生长动力学、代谢以及细胞周期的变化。结果50Hz,20mT的极低频磁场对SK-HEP-1细胞的生长与代谢有抑制作用,并能阻碍其有丝分裂的进行。结论50Hz,20mT的极低频磁场为治疗人类恶性肿瘤提供了一种可能的手段。     

磁场对恶性肿瘤生长的抑制作用

宿主和恶性肿瘤之间的相互作用和生物电磁现象有关。磁场影响肿瘤生长的报道较多,由于磁场的生物效应及其机制都很复杂,进一步研究工作是需要的,我们观测到一定参数的脉冲梯度磁场在不同生物层次上抑制鼠恶性肿瘤生长,磁场诱发癌细胞凋亡和阻塞供应肿瘤的新生血管,由于脉冲梯度磁场抑制癌生长,所以它能成为一种辅助治疗癌症的新方法。     

极低频磁场对人肝癌细胞生长、代谢及细胞周期的影响

目的：研究一定参数的极低频磁场对人肝癌细胞（SK-HEP-1）在诸多方面的影响。方法：在整个SK-HEP-1细胞的培养周期中用50Hz,20mT的极低频磁场对其进行作用,并检测作用后细胞的增殖活性、生长动力学、代谢以及细胞周期的变化。结果：50Hz．20mT的极低频磁场对SK-HEP-1细胞的生长与代谢有抑制作用,并能阻碍其有丝分裂的进行。结论：50Hz,20mT的极低频磁场为治疗人类恶性肿瘤提供了一种可能的手段。     

磁场对微循环影响的研究进展

磁场的生物学效应是磁场和生物体两者共同作用的结果,是与两者的参数密切相关的.磁场参数包括磁场类型,场强大小,作用时间等,这些参数是影响磁场生物学效应的主要因素.磁生物学是研究不同的外加磁场对不同种类和不同层次生物结构单元的生物学效应及其作用机制的科学.电磁场对生物膜的离子转运能力的影响会导致机体一些生化和生理过程的变化,从而影响与生物电活动相关的各种过程.本文概述了近年磁场对微循环影响的研究成果.     

0．23T稳恒磁场对不同温度离体过氧化氢酶的磁效应研究

研究了 0 .2 3T稳恒磁场对不同温度下的离体牛肝过氧化氢酶 (CAT)构象及活力的影响 ,并从分子水平讨论了磁场对不同温度的过氧化氢酶产生不同生物学效应的可能机制。将不同温度的天然酶液置于磁感应强度为0 .2 3T的磁场中分别处理一定的时间 ,处理过程中保持环境温度与酶液温度一致 ,撤离磁场后立即在相同实验条件下对其进行光谱分析及量热分析 ,并用Beers&Sizers法 (改良型 )测定酶活力。结果表明 ,磁场使 2 5℃过氧化氢酶的构象发生明显变化 ,表现为荧光偏振度增加、出现明显的差示扫描量热曲线、产生λ2 10nm～ 310nm的紫外差光谱以及λ330nm荧光发射峰的荧光强度改变 (荧光发射峰的峰位未移动 ) ,构象变化的同时酶活力增加 ;15℃过氧化氢酶的构象及活力变化规律与 2 5℃过氧化氢酶类似 ,但强度均弱于 2 5℃酶 ;而 4℃过氧化氢酶的构象及活力没有发生变化 ,表现出未受磁场处理的影响。相同实验条件下 ,磁场对不同温度的酶分子影响不同 ,随温度的增加 ,影响效应趋于显著。由于不同温度的酶分子之间的差异在于构象状态的不同 ,这表明酶分子自身的构象状态对磁场处理效果有极其重要的影响。不同温度的过氧化氢酶磁效应差异显著可能是由磁致酶构象变化的特殊机制所引起。磁场对酶分子构象的影响可能是通     

弱极低频磁场对Actin骨架组装效率的频率窗口效应初探

前期研究发现,50 Hz弱磁场辐照能明显降低细胞的微丝含量和组装效率,对actin骨架形态也有明显影响.电磁生物学效应是否与辐照场频率相关,一直受到研究者的关注.单体球状肌动蛋白(G-actin)是带电结构,电磁场频率会影响其振荡频率并对微丝聚合效率产生影响.本文从细胞骨架形态和蛋白质两层次,采用免疫荧光技术考察0.4 m T,在35~140 Hz范围内5个频率的极低频磁场(ELF-MF)对FL细胞中纤维状肌动蛋白(F-actin)含量的影响,并采用荧光共振能量转移技术(FRET)验证效应最明显的频率对离体G-actin组装效率的干扰程度.结果显示,相比假辐照组,细胞中F-actin含量在50 Hz辐照组下降了(34.66±3.14)%,110 Hz次之,而另外3组(35、70和140 Hz)无显著性差异.同时利用FRET方法验证,在50 Hz磁场辐照下,离体环境中G-actin组装成F-actin的效率较假辐照组、35和70 Hz组显著降低.经初步分析,G-actin在弱ELF-MF中受到以洛伦兹力和感生电场力的合力为主的相关电磁力干扰,致使组装效率下降,且由于工频磁场周期与微丝组装周期的特殊相干性,在50 Hz频率附近可能存在一个外磁场干扰actin骨架组装的频率窗口.     

Effects of extremely low-frequency magnetic field on growth and differentiation of human mesenchymal stem cells

Human Mesenchymal Stem Cells (hMSCs) were exposed to a developed extremely low-frequency (ELF) magnetic fields (50?Hz ,20?mT ELF) system to evaluate whether exposure to (ELF) magnetic fields affects growth, metabolism, and differentiation of hMSCs. MTT method was used to determine the growth and metabolism of hMSCs following exposure to ELF magnetic fields. Na(+)/K(+) concentration and osmolality of extracellular were measured after exposured culture. Alkaline phosphatase (ALP) assay and Calcium assay, ALP staining, and Alizarin red staining were performed to evaluate the osteogenic differentiation of hMSCs under the ELF magnetic field exposure. In these experiments, the cells were exposed to ELF for up to 23 days. The results showed that exposure to ELF magnetic field could inhibit the growth and metabolism of hMSC, but have no significant effect on differentiation of hMSCs. These results suggested that ELF magnetic field may influence the early development of hMSCs related adult cells.     

Effects of Extremely Low-Frequency Magnetic Field on Growth and Differentiation of Human Mesenchymal Stem Cells

Human Mesenchymal Stem Cells (hMSCs) were exposed to a developed extremely low-frequency (ELF) magnetic fields (50?Hz ,20?mT ELF) system to evaluate whether exposure to (ELF) magnetic fields affects growth, metabolism, and differentiation of hMSCs. MTT method was used to determine the growth and metabolism of hMSCs following exposure to ELF magnetic fields. Na⁺/K⁺ concentration and osmolality of extracelluar were measured after exposured culture. Alkaline phosphatase (ALP) assay and Calcium assay, ALP staining, and Alizarin red staining were performed to evaluate the osteogenic differentiation of hMSCs under the ELF magnetic field exposure. In these experiments, the cells were exposed to ELF for up to 23 days. The results showed that exposure to ELF magnetic field could inhibit the growth and metabolism of hMSC, but have no significant effect on differentiation of hMSCs. These results suggested that ELF magnetic field may influence the early development of hMSCs related adult cells.     

ELF magnetic field affects proliferation of SPD8/V79 Chinese hamster cells but does not interact with intrachromosomal recombination

Extremely low-frequency (ELF) magnetic fields have previously been shown to affect conformation of chromatin, cell proliferation, and calcium metabolism. Possible mutagenic and carcinogenic effects of ELF have also been discussed and tested. In this study, intrachromosomal recombination in the hprt gene after exposure to ELF magnetic field was investigated using the SPD8 recombination assay. SPD8 cells, derived from V79 Chinese hamster cells were exposed to ELF at a specific combination of static and ELF magnetic fields, that has been proven to have effects on chromatin conformation in several cell types. The genotoxic agent camptothecin (CPT) was used either as a positive control or simultaneously with ELF. We also analysed the effect of ELF and CPT on chromatin conformation with the anomalous viscosity time dependence (AVTD) technique, cell growth kinetics, and cell survival with clonogenic assay. DNA fragmentation was analysed by pulsed field gel electrophoresis (PFGE). ELF did not induce recombination alone, neither did ELF modify the recombinogenic effect of CPT. Although, there was no effect on cell survival in response to ELF exposure, inhibition of cell growth was observed. On the other hand, ELF exposure partly counteracted the growth inhibition seen with CPT. The data suggest that ELF exposure may stimulate or inhibit cell growth depending on the state of the cells. Although, ELF did not induce recombination, a weak but statistically significant DNA fragmentation comparable with CPT-induced fragmentation was observed with PFGE 48h after exposure to ELF.     

Toxicity and SOS response to ELF magnetic field and nalidixic acid in E. coli cells

Extremely low frequency (ELF) magnetic fields have previously been shown to affect conformation of chromatin and cell proliferation. Possible genotoxic and carcinogenic effects of ELF have also been discussed and tested. In this study, we analyzed the effect of ELF on chromatin conformation in E. coli GE499 cells by the anomalous viscosity time dependence (AVTD) technique. Possible genotoxic ELF effects at the specific combination of static and ELF magnetic fields, that has been proven to have effects on chromatin conformation, were investigated by clonogenic assay, cell growth kinetics, and analysis of SOS-response using inducible recA-lacZ fusion and the β-galactosidase assay. Genotoxic agent nalidixic acid (NAL) was used as positive control and in combination with ELF. Nalidixic acid at 3-30μg/ml decreased the AVTD peaks and induced cytotoxic effect. In contrast to NAL, ELF increased AVTD, stimulated cell growth, and increased cloning efficiency. These effects depended on frequency within the frequency range of 7-11Hz. While NAL induced SOS response, ELF exposure did not induce the recA-lacZ fusion. Exposure to ELF did not modify the genotoxic effects of NAL either. All together, the data show that ELF, under specific conditions of exposure, acted as nontoxic but cell growth stimulating agent.     

Effects of Weak Environmental Magnetic Fields on the Spontaneous Bioelectrical Activity of Snail Neurons

We examined the effects of 50-Hz magnetic fields in the range of flux densities relevant to our current environmental exposures on action potential (AP), after-hyperpolarization potential (AHP) and neuronal excitability in neurons of land snails, Helix aspersa. It was shown that when the neurons were exposed to magnetic field at the various flux densities, marked changes in neuronal excitability, AP firing frequency and AHP amplitude were seen. These effects seemed to be related to the intensity, type (single and continuous or repeated and cumulative) and length of exposure (18 or 20 min). The extremely low-frequency (ELF) magnetic field exposures affect the excitability of F1 neuronal cells in a nonmonotonic manner, disrupting their normal characteristic and synchronized firing patterns by interfering with the cell membrane electrophysiological properties. Our results could explain one of the mechanisms and sites of action of ELF magnetic fields. A possible explanation of the inhibitory effects of magnetic fields could be a decrease in Ca²⁺ influx through inhibition of voltage-gated Ca²⁺ channels. The detailed mechanism of effect, however, needs to be further studied under voltage-clamp conditions.     

Exposure to power frequency magnetic fields suppresses X-ray-induced apoptosis transiently in Ku80-deficient xrs5 cells

In an attempt to determine whether exposure to extremely low frequency (ELF) electromagnetic fields can affect cells, Ku80-deficient cells (xrs5) and Ku80-proficient cells (CHO-K1) were exposed to ELF electromagnetic fields. Cell survival, and the levels of the apoptosis-related genes p21, p53, phospho-p53 (Ser(15)), caspase-3 and the anti-apoptosis gene bcl-2 were determined in xrs5 and CHO-K1 cells following exposure to ELF electromagnetic fields and X-rays. It was found that exposure of xrs5 and CHO-K1 cells to 60 Hz ELF electromagnetic fields had no effect on cell survival, cell cycle distribution and protein expression. Exposure of xrs5 cells to 60 Hz ELF electromagnetic fields for 5 h after irradiation significantly inhibited G(1) cell cycle arrest induced by X-rays (1 Gy) and resulted in elevated bcl-2 expression. A significant decrease in the induction of p53, phospho-p53, caspase-3 and p21 proteins was observed in xrs5 cells when irradiation by X-rays (8 Gy) was followed by exposure to 5 mT ELF magnetic fields. Exposure of xrs5 cells to the ELF electromagnetic fields for 10 h following irradiation significantly decreased X-ray-induced apoptosis from about 1.7% to 0.7%. However, this effect was not found in CHO-K1 cells within 24 h of irradiation by X-rays alone and by X-rays combined with ELF electromagnetic fields. Exposure of xrs5 cells to 60 Hz ELF electromagnetic fields following irradiation can affect cell cycle distribution and transiently suppress apoptosis by decreasing the levels of caspase-3, p21, p53 and phospho-p53 and by increasing bcl-2 expression.