短期强磁场暴露对金黄地鼠视网膜内多巴胺含量的影响

目的研究0．1Hz极低频交变磁场全身暴露对金黄地鼠眼视网膜内多巴胺含量的影响。方法36只成熟雄性金黄地鼠随机分为4组，每组9只，1组为对照组，另3组分别全身间断暴露于50、75、100mT交变磁场7d，每天暴露8h，然后测定视网膜内神经递质多巴胺含量。结果场强在50mT时，地鼠视网膜内多巴胺含量变化无统计学意义（P〉0．05），而在75、100mT时地鼠视网膜内多巴胺含量增加有统计学意义（P〈0．01）。100mT比75mT时地鼠视网膜内多巴胺含量增加有统计学意义（P〈0．05）。结论全身暴露磁场强度到达一定水平时可刺激金黄地鼠视网膜内多巴胺的合成和分泌，强度越强作用越明显，若长期的强磁场暴露将可能因视网膜内多巴胺含量的变化而影响视网膜的功能。     

15 Hz磁场刺激对大鼠局灶性脑创伤影响的实验研究

目的：研究15Hz磁场对大鼠脑创伤的影响。方法：采用大鼠局灶性左脑创伤模型，每天对大鼠头部进行正弦交变磁场（15Hz、18mT）刺激2h，分别作用3d或8d，同时设立对照组。双盲法病理切片观察。结果：与对照组相比，磁场组炎细胞反应减轻，神经元变性坏死程度减轻，8d时更为明显；远离创伤灶的皮层二、三层出现深染的呈长形（或变形）的特殊神经元，且磁场组的这种特殊神经元的数量和分布面积均明显高于对照组，尤以8d时更为显著。结论：所用ELMF可在一定程度上促进脑创伤的恢复，远离创伤区的特殊神经元的产生机制及其在脑创伤后恢复过程中的作用，有待进一步研究。     

骨细胞MLO-Y4在不同强度静磁场下的生物学效应

目的研究骨样细胞系MLO-Y4在不同强度静磁场下的生物学效应。方法 MLO-Y4细胞接受场强为500nT亚磁场、0.2T中强磁场及16T强磁场作用后,CCK8法检测细胞活性,HE染色分析细胞形态变化,实时定量PCR方法检测骨细胞功能相关基因的表达,ELISA或化学试剂盒检测骨细胞可溶性细胞因子的分泌,收集处理后的条件培养基诱导成骨细胞矿化及破骨细胞形成。结果与对照组相比,亚磁场对骨细胞活性和形态无影响,促进了RANKL而抑制了Cx43的基因表达,促进了细胞因子M-CSF的分泌,其条件培养基对成骨细胞矿化无影响,但促进了破骨细胞形成。中强磁场对细胞活性无影响,增加了骨细胞突触数目,其条件培养基对成骨和破骨细胞分化都无明显影响。16T强磁场促进了骨细胞活性及细胞突触数目,抑制了RANKL而促进iNOS和Cx43基因表达,促进ALP和NO而抑制M-CSF分泌,其条件培养基对成骨细胞矿化无影响,但抑制了破骨细胞形成。结论骨细胞MLO-Y4在500nT亚磁场下表现为负向的生物学效应,0.2T中强磁场下无明显生物学行为变化,而在16T强磁场下表现为积极的生物学效应。     

恒磁场对脂多糖诱导内皮细胞与中性粒细胞黏附及细胞间黏附分子表达影响的研究

目的研究恒磁场对脂多糖(LPS)诱导中性粒细胞与内皮细胞黏附及内皮细胞表达细胞间黏附分子的影响。方法人脐静脉内皮细胞于0·05、0·1、1mT的磁场中曝磁,用LPS刺激内皮细胞,内皮细胞与中性粒细胞黏附用细胞计数法评估,内皮细胞表面细胞间黏附分子表达用流式细胞仪及酶联免疫吸附法测定。结果LPS刺激后,中性粒细胞的黏附率为58%;0·05、0·1mT磁场条件下中性粒细胞黏附率下降为40%及38%,与单纯LPS组比较明显下降(P<0·05),而1mT组中性粒细胞黏附率为65%,与单纯LPS组相近。单纯LPS组细胞间黏附分子表达为10·34±0·33/0·89±0·16;0·05、0·1mT磁场条件下细胞黏附分子表达为6·61±0·17/0·53±0·18、6·98±0·15/0·46±0·10,与单纯LPS组比较明显下降(P<0·05);1mT组为10·99±0·41/0·78±0·15,与单纯LPS组比较无明显差异。结论0·05、0·1mT可以抑制LPS刺激下内皮细胞与中性粒细胞的黏附及内皮细胞表面细胞间黏附分子的表达。     

5 Hz和20 Hz磁场对中脑神经干细胞分化的影响

目的：观察5Hz和20Hz磁场（EMF）对新生大鼠中脑神经干细胞神经元向分化的影响。方法：神经干细胞分别置于5Hz和20Hz正弦交变磁场（8mT）中诱导变化，每天上午、下午各1次，每次15min，分别作用于1d、5d或10d，同时设立相应的对照组。利用神经元特异性标记物MAP2抗体进行免疫荧光染色，计数MAP2阳性细胞的百分比。结果：5Hz和20Hz交变磁场干预1d，均出现对NSC分化方向的显著影响，即促进NSC神经元的分化；20Hz电磁场随干预时程的延长，NSC分化为神经元的比例逐渐增高，以10d组神经元比例最高；5Hz磁场干预5d时神经元比例最高，10d时有所下降，但仍高于对照组；20Hz磁场效应在10d时显著大于5Hz磁场。结论：5Hz和20Hz电磁场以不同的效应模式促进NSC神经元向的分化，电磁场可以成为NSC定向分化研究的重要手段之一。     

模拟舰船强磁场生物效应的实验研究(论著)

目的：研究舰船上０．１Ｈｚ极低频交变磁场和恒定磁场全身暴露的生物效应及其作用阈值。方法：实验动物全身间断暴露于２５～１００ｍＴ交变或恒定磁场７或１４天，或连续暴露于３ｍＴ交变磁场５或１０天；然后分别测定其对微血管、神经肽、骨髓及免疫功能的影响。结果：当场强在７５和１００ｍＴ时，实验兔球结膜毛细血管和微静脉显著扩张，而在２５和５０ｍＴ时也有扩张趋势。场强在７５和１００ｍＴ时，大鼠下丘脑和垂体及血浆中β－内啡肽（β－Ｅｐ）和精氨酸加压素（ＡＶＰ）含量显著升高，在２５和５０ｍＴ时作用不明显，而３ｍＴ交变磁场使含量下降。场强在７５ｍＴ时，对实验兔和大鼠骨髓细胞增生活力有非常显著的促进作用。结论：磁场具有扩张微血管、改善微循环的作用，且随着场强的增大，作用逐渐加强。低强度磁场抑制神经肽的合成与分泌，高强度促进合成与分泌。强场在７５ｍＴ时，对骨髓细胞增生活力有非常显著的促进作用。交变和恒定磁场的场强和暴露时间相同时，对机体的影响基本一致     

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。     

静磁场辐射对大鼠心脏功能和结构的影响研究

目的研究静磁场辐射对大鼠心脏生理功能与组织结构的影响,为静磁场辐射损伤机制研究奠定基础。方法将20只Wistar雄性大鼠置于600 mT的静磁场中,每天辐射12 h,连续7 d。大鼠于辐射后7 d和14 d检测心率和心电图变化后活杀,取心肌组织入10%甲醛缓冲溶液固定、石蜡包埋、HE染色,光镜观察心脏组织结构改变。结果 600 mT静磁场辐射后7 d,大鼠心电图显示心率显著下降（P〈0.01）,P波时程以及T-H较对照组显著升高（P〈0.05或0.01）;辐射后14 d,大鼠心率以及R-H较辐射前显著下降（P〈0.01）,而T-H较辐射前显著升高（P〈0.05）。600 mT静磁场辐射后7 d,大鼠室间隔及心内膜下心肌细胞嗜酸性变、肌纤维凝聚,核固缩;心肌纤维呈波浪状排列;血管扩张、淤血,管腔内见血浆蛋白和红细胞混杂,示血栓形成;辐射后14 d,上述病变进一步加重。结论 600 mT静磁场辐射可对大鼠心脏功能和结构造成损伤,表现为心电图异常、心脏血液循环障碍,心肌细胞变性和坏死,并在辐射后2周内呈加重趋势。     

静磁场辐射对大鼠外周血细胞、血清代谢酶和血浆递质的影响

目的探讨静磁场连续辐射对大鼠外周血细胞、血清代谢酶和血浆递质的影响。方法二级雄性Wistar大鼠20只,随机分为对照组和静磁场辐射组,静磁场强度为600 mT,每天辐射12 h,连续7 d,于辐射后7 d、14 d和30 d活杀取材。采用Sysmex 2100全自动血细胞分析仪进行血细胞分析;采用全自动生化分析仪检测大鼠血清天冬氨酸转氨酸（谷草转氨酶,AST,GOT）、乳酸脱氢酶（LDH）和肌酸激酶同工酶（CKMB）的改变,采用HPLC检测大鼠血浆中氨基酸和单胺类递质的改变。结果 600mT静磁场辐射后7 d,大鼠外周血淋巴细胞百分率显著降低（P〈0.05）,血小板（PLT）显著减少（P〈0.01）,辐射后14 d,红细胞（RBC）显著升高（P〈0.05）。辐射后7 d和14d,大鼠血清AST和LDH显著减少（P〈0.01）,辐射后14 d,CKMB显著减少（P〈0.01）。辐射后7 d,大鼠血浆犬尿喹啉酸（KYNA）和谷氨酸（Glu）含量显著降低（P〈0.01）,NE和5-HT含量均显著减少（P〈0.05或P〈0.01）。结论 600mT静磁场连续辐射可引起外周血淋巴细胞百分率和PLT减少、RBC增加,血清代谢酶AST、LDH和CKMB减少,血浆氨基酸和单胺类递质代谢紊乱。     

细胞凋亡及相关Bcl-2蛋白在大鼠肝促癌中的作用

目的：研究大鼠肝癌促癌阶段促癌物苯巴比妥（PB）对细胞凋亡的作用及其相关基因Bcl-2表达情况。方法：复制大鼠肝癌启动／促进模型,采用TUNEL法检测各实验组不同时相眯细胞凋亡率,免疫组化SABC法检测Bc1-2基因蛋白表达情况。结果：高、中、低剂量组和启动组随着时相点的延长细胞凋亡率是降低的,且各时相点间凋亡率均值比较差异显著（P＜0．05）,而正常组和单纯促癌组各时相眯凋亡率基本稳定,无显著差异（P＞0．05）。撤除组当撤除PB后细胞凋亡率显著升高,与撤除前一时相点比较差异显著（P＜0．05）。Bcl-2基因蛋白表达在高、中剂量组随着时相点的延长呈现增加的趋势,且各时相点间均值比较差异显著（P＜0．05）。低剂量组和启动组随着时相点的延长Bcl-2基因蛋白表达呈下降趋势,但各时相点间比较差异不显著（P＞0．05）。政党组和单纯促癌组各时相点Bcl-2基因蛋白表达基本稳定,无显著差异（P＞0．05）。撤除组当撤除PB后Bcl-2基因蛋白表达显著降低,与撤除前一时相点比较差异显著（P＜0．05）。结论：在大鼠肝促癌阶段,促癌物PB能抑制大鼠肝癌前病变的细胞调亡,增加凋亡相关Bcl-2基因蛋白表达,提示凋亡的抑制可能是促癌作用的机制之一,凋亡的抑制与Bcl-2基因蛋白表达的增加有关。     

Inhibition of UV-induced G1 arrest by exposure to 50 Hz magnetic fields in repair-proficient and -deficient yeast strains

PURPOSE: To assess the possibility that extremely low frequency (ELF) magnetic fields obstruct the damage repair process, the gene conversion frequency and cell cycle kinetics in a DNA repair-proficient and nucleotide excision repair (NER)-deficient strain of diploid yeast Saccharomyces cerevisiae. MATERIALS AND METHODS: DNA repair- or NER-deficient cells were irradiated with sublethal doses of ultraviolet light (UV) radiation followed by exposure to 50 Hz magnetic fields up to 30 mT for 48 h. After exposure, colony-forming ability was scored as revertants in which gene conversion had restored the functional allele of the ARG4 gene conversion hotspot. Cell cycle analysis was performed using flow cytometry. RESULTS: Gene conversion rate was increased by the combined exposure in DNA repair-proficient cells, whereas it remained unchanged between UV alone and the combined exposure in NER-deficient cells. The UV-induced G1 arrest was inhibited by exposure to 30 mT ELF magnetic fields in both repair-proficient and -deficient cells. CONCLUSIONS: The results suggest that exposure to high-density (30 mT) ELF magnetic fields decreases the efficiency of NER by suppressing G1 arrest, which in turn led to enhancement of the UV-induced gene conversion.     

Extremely low frequency (ELF) magnetic fields enhance chemically induced formation of apurinic/apyrimidinic (AP) sites in A172 cells

PURPOSE: To detect the effects of extremely low frequency (ELF) magnetic fields, the number of apurinic/apyrimidinic (AP) sites in human glioma A172 cells was measured following exposure to ELF magnetic fields. MATERIALS AND METHODS: The cells were exposed to an ELF magnetic field alone, to genotoxic agents (methyl methane sulfonate (MMS) and hydrogen peroxide (H2O2)) alone, or to an ELF magnetic field with the genotoxic agents. After exposure, DNA was extracted, and the number of AP sites was measured. RESULTS: There was no difference in the number of AP sites between cells exposed to an ELF magnetic field and sham controls. With MMS or H2O2 alone, the number of AP sites increased with longer treatment times. Exposure to an ELF magnetic field in combination with the genotoxic agents increased AP-site levels compared with the genotoxic agents alone. CONCLUSIONS: Our results suggest that the number of AP sites induced by MMS or H2O2 is enhanced by exposure to ELF magnetic fields at 5 millitesla (mT). This may occur because such exposure can enhance the activity or lengthen the lifetime of radical pairs.     

Inhibition of UV‐induced G1 arrest by exposure to 50 Hz magnetic fields in repair‐proficient and ‐deficient yeast strains

Purpose: To assess the possibility that extremely low frequency (ELF) magnetic fields obstruct the damage repair process, the gene conversion frequency and cell cycle kinetics in a DNA repair‐proficient and nucleotide excision repair (NER)‐deficient strain of diploid yeast Saccharomyces cerevisiae.

Materials and methods: DNA repair‐ or NER‐deficient cells were irradiated with sublethal doses of ultraviolet light (UV) radiation followed by exposure to 50?Hz magnetic fields up to 30?mT for 48?h. After exposure, colony‐forming ability was scored as revertants in which gene conversion had restored the functional allele of the ARG4 gene conversion hotspot. Cell cycle analysis was performed using flow cytometry.

Results: Gene conversion rate was increased by the combined exposure in DNA repair‐proficient cells, whereas it remained unchanged between UV alone and the combined exposure in NER‐deficient cells. The UV‐induced G1 arrest was inhibited by exposure to 30?mT ELF magnetic fields in both repair‐proficient and ‐deficient cells.

Conclusions: The results suggest that exposure to high‐density (30?mT) ELF magnetic fields decreases the efficiency of NER by suppressing G1 arrest, which in turn led to enhancement of the UV‐induced gene conversion.     

50mT超低频磁场96h暴露对家兔脑电的影响

本文报道了50mT超低频磁场99h 暴露对兔脑电的影响。结果表明,该环境可使家兔脑电在低频段成份增加、两导程脑电在低频段的协调性增强、大脑的传递功能趋向抑制等。提示应注意特种环境中的超低频磁场污染问题,     

A 700 MHz 1H-NMR study reveals apoptosis-like behavior in human K562 erythroleukemic cells exposed to a 50 Hz sinusoidal magnetic field

PURPOSE: To study cell damage and possible apoptosis in K562 human erythroleukemic cells exposed for 2 h to an extremely low frequency (ELF) 50 Hz sinusoidal magnetic field with a magnetic induction of either 1 or 5 mT using high resolution proton nuclear magnetic resonance (1H-NMR) spectroscopy. MATERIALS AND METHODS: One-dimensional 1H-NMR spectra were obtained on whole K562 cells and perchloric acid extracts of these cells. In addition, two-dimensional 1H-NMR spectra were also acquired. Cell damage was examined by lactate dehydrogenase release and changes in cell growth were monitored by growth curve analyses, bromodeoxyuridine incorporation and Ki67 antigen localization. Cell death (necrosis and apoptosis) were also studied by using the chromatin dye Hoechst 33258. RESULTS: The variations in numerous metabolites observed with 1H-NMR reveal apoptosis-like behavior in response of K562 cells to ELF fields. CONCLUSION: 1H-NMR can be extremely useful in studying the effects of ELF fields on cells. In particular, the variations in metabolites which suggest apoptosis-like behavior occur when the cells are not identifiable as apoptotic by more traditional techniques.     

Lack of acute effects of 20 mT, 50 Hz magnetic fields on murine haemopoiesis

Some epidemiological studies have drawn attention to a possible association between exposure to extremely low-frequency (ELF) electromagnetic fields and the development of acute myeloid leukaemia (AML) in adults. At present there is no experimental evidence for such an association. We have investigated the acute effects of power frequency magnetic fields on haemopoiesis in CBA/H mice known to be susceptible to the induction of AML after exposure to ionizing radiation. Up to 19 days after exposure to 50 Hz fields at 20 mT for 7 days no significant effects on peripheral blood characteristics were observed. Assays of the bone marrow stem cells and myelomonocytic progenitor cells also failed to reveal significant effects. Our experiments cannot, however, rule out subtle effects on cell population dynamics, and further investigations, including long-term studies, are required to establish the extent to which ELF magnetic fields might affect the haemopoietic system.     

Lack of Acute Effects of 20 mT, 50 Hz Magnetic Fields on Murine Haemopoiesis

Summary

Some epidemiological studies have drawn attention to a possible association between exposure to extremely low-frequency (ELF) electromagnetic fields and the development of acute myeloid leukaemia (AML) in adults. At present there is no experimental evidence for such an association. We have investigated the acute effects of power frequency magnetic fields on haemopoiesis in CBA/H mice known to be susceptible to the induction of AML after exposure to ionizing radiation. Up to 19 days after exposure to 50 Hz fields at 20 mT for 7 days no significant effects on peripheral blood characteristics were observed. Assays of the bone marrow stem cells and myelomonocytic progenitor cells also failed to reveal significant effects. Our experiments cannot, however, rule out subtle effects on cell population dynamics, and further investigations, including longterm studies, are required to establish the extent to which ELF magnetic fields might affect the haemopoietic system.     

A 700 MHz 1H-NMR study reveals apoptosis-like behavior in human K562 erythroleukemic cells exposed to a 50 Hz sinusoidal magnetic field

Purpose: To study cell damage and possible apoptosis in K562 human erythroleukemic cells exposed for 2?h to an extremely low frequency (ELF) 50 Hz sinusoidal magnetic field with a magnetic induction of either 1 or 5 mT using high resolution proton nuclear magnetic resonance (¹H-NMR) spectroscopy.

Materials and methods: One-dimensional ¹H-NMR spectra were obtained on whole K562 cells and perchloric acid extracts of these cells. In addition, two-dimensional ¹H-NMR spectra were also acquired. Cell damage was examined by lactate dehydrogenase release and changes in cell growth were monitored by growth curve analyses, bromodeoxyuridine incorporation and Ki67 antigen localization. Cell death (necrosis and apoptosis) were also studied by using the chromatin dye Hoechst 33258.

Results: The variations in numerous metabolites observed with ¹H-NMR reveal apoptosis-like behavior in response of K562 cells to ELF fields.

Conclusion: ¹H-NMR can be extremely useful in studying the effects of ELF fields on cells. In particular, the variations in metabolites which suggest apoptosis-like behavior occur when the cells are not identifiable as apoptotic by more traditional techniques.     

Extremely low frequency magnetic field (50 Hz, 0.5 mT) modifies fitness components and locomotor activity of Drosophila subobscura

Abstract

Purpose: Extremely low frequency (ELF) magnetic fields are essential ecological factors which may induce changes in many organisms. The aim of this study was to examine the effects in Drosophila subobscura exposed for 48 h to ELF magnetic field (50 Hz, 0.5 mT) at different developmental stages.

Materials and methods: Egg-first instar larvae developmental stage of D. subobscura isofemale lines was exposed to ELF magnetic field, and fitness components (developmental time, developmental dynamics, viability and sex ratio) and locomotor activity of three-day-old males and females were monitored. Also, just eclosed D. subobscura isofemale adults were exposed to ELF magnetic field and their locomotor activity was monitored just after.

Results: ELF magnetic field shortens developmental time, increases viability and does not affect sex ratio of D. subobscura. No matter which developmental stage is exposed, ELF magnetic field significantly decreases locomotor activity of adult flies, but after exposure of just eclosed adults observed change lasts longer.

Conclusions: Applied ELF magnetic field modifies fitness components and locomotor activity of D. subobscura. Observed effects can be attributed to the influence of magnetic field on different stages of development where the hormonal and nervous systems play important role in the control of examined parameters.     

Different responses of Drosophila subobscura isofemale lines to extremely low frequency magnetic field (50 Hz, 0.5 mT): fitness components and locomotor activity

Purpose: Extremely low frequency (ELF) magnetic fields as essential ecological factors may induce specific responses in genetically different lines. The object of this study was to investigate the impact of the ELF magnetic field on fitness components and locomotor activity of five Drosophila subobscura isofemale (IF) lines.

Materials and methods: Each D. subobscura IF line, arbitrarily named: B16/1, B24/4, B39/1, B57/2 and B69/5, was maintained in five full-sib inbreeding generations. Their genetic structures were defined based on the mitochondrial DNA variability. Egg-first instar larvae and 1-day-old flies were exposed to an ELF magnetic field (50?Hz, 0.5?mT, 48?h) and thereafter, fitness components and locomotor activity of males and females in an open field test were observed for each selected IF line, respectively.

Results: Exposure of egg-first instar larvae to an ELF magnetic field shortened developmental time, and did not affect the viability and sex ratio of D. subobscura IF lines. Exposure of 1-day-old males and females IF lines B16/1 and B24/4 to an ELF magnetic field significantly decreased their locomotor activity and this effect lasted longer in females than males.

Conclusions: These results indicate various responses of D. subobscura IF lines to the applied ELF magnetic field depending on their genetic background.