胞间耦合和电磁场对多细胞钙振荡的影响

目的:研究电磁场对多细胞系统(三个细胞)钙振荡同步性的影响.方法:基于肝细胞动力学模型,以胞间耦合和电磁场引起的细胞三磷酸肌醇(IP3)浓度的变化作为影响因子,采用数值分析的方法,研究电磁场的频率、强度对钙振荡的影响.结果:细胞差异性导致钙振荡的不同,在相同的耦合因子下,细胞数不同导致钙振荡形式存在差异;胞间耦合影响多细胞钙振荡的同步性.结论:电磁场的频率、强度(调制因子)引起钙振荡的频率和幅值发生变化.     

极低频磁场对胞内钙振荡影响的机理分析

基于双钙库模型,本文以离子跨过细胞膜、细胞器膜迁移的几率作为细胞对电磁场的响应因子,来调制流过膜通道的离子的速率,进而影响细胞内钙离子的浓度。数值分析表明:在极低频磁场的作用下,一定能量因子下的频率条件或是一定频率因子下的能量条件可引起钙振荡形式的变化;窗效应是频率因子和能量因子共同作用的结果。     

基于电磁生物效应伪随机广谱信号源的设计

目的:实现粮食产后减损,驱灭老鼠.方法:利用低频电磁场对鼠类生物效应研究的基础结合广谱复合频率信号的特性.以AT89S51单片机为依托提出了能发射出复合频率信号的伪随机广谱复合频率信号源的设计方案.结果:结果显示信号的广谱特性稳定而且该信号和其相应产生的电磁场的参数理论上能够满足实验的需要.结论:该信号源的设计是可行的,能够达到预期的目的.     

离子跨膜迁移的几率波理论

基于细胞结构、已有的机理分析理论和实验事实,我们提出解释电磁场生物学窗效应的几率波理论。该理论将细胞膜通道看成是周期性分布的势垒,给出了离子跨膜迁移的物理图像;修正了膜通道内离子能量相对于外加电磁场频率的关系;应用波函数的概念,给出了低强度电磁场作用下,离子跨膜迁移的几率。数值仿真结果分析了影响离子跨膜迁移的物理因素。结果显示该理论可解释电磁场生物学窗效应的现象。     

极低频磁场对基因转录影响的研究

电磁场对生物体的非热效应及其机制研究是生物电磁学的前沿课题。由于电磁场诱导细胞功能改变必然涉及到基因转录的改变，因此从研究电磁场对基因转录影响来探究其机制是近几年该领域的重点。本文就国际上有关极低频磁场对基因转录的重要研究及发展状况，尤其对电磁波辐射源的信号特征（频率、波形、强度）及其它关键参数对基因转录影响的关系作了评述，并展望该领域的研究前景     

极低频伪随机无定向旋转磁场驱灭鼠系统研制

目的:设计一种2n系列基频的广谱复合频率脉冲电磁场,用于规避鼠害的研究和电磁场对啮齿动物神经影响的试验装置.方法:系统由24VDC电源及MCU、DC-DC电路、隔离驱动模块、逆变模块、过流检测保护模块、磁场方向控制模块以及显示、时钟模块、辐射器等构成.结果:随机8个磁场方向形成碟形旋转磁场,并具备2n多频信号伪随机性.结果:极低频驱灭鼠系统稳定运行,方向频率伪随机变化,电源利用率高,可用于规避鼠害、研究电磁场对生物的生殖、神经系统影响的试验.     

极低频磁场对基因转录影响的研究

电磁场对生物体的非热效应及其机制研究是生物电磁学的前沿课题。由于电磁场诱导细胞功能改变必然涉及到基因转录的改变，因此从研究电磁场对基因转录影响来探究其机制是近几年该领域的重点。本文就国际上有关极低频磁场对基因转录的重要研究及发展状况，尤其对电磁波辐射源的信号特征（频率、波形、强度）及其它关键参数对基因转录的关系作了评述，并展望该领域的研究前景。     

极低频三角形电磁场对成骨细胞的影响

目的:观察三角形极低频电磁场对新生大鼠颅盖骨成骨细胞增殖与分化的影响.方法:采用频率为15Hz、不同强度、不同形状的三角形电磁场作用于成骨细胞,测量成骨细胞的增殖与碱性磷酸酶活性(ALP).结果:频率为15 Hz, 强度为4 mT～5 mT,三角形电磁场能够显著提高成骨细胞的增殖率和ALP的活性,而强度为8 mT时则显著抑制成骨细胞的增殖与ALP的活性;不同形状的三角形电磁场也明显影响成骨细胞的功能,其中以p为38%、85%对成骨细胞的影响最为明显.结论:电磁场的生物学效应依赖于其参数特征.     

脉冲磁场与前软骨干细胞向成熟软骨细胞的增殖与分化:与Ihh/PTHrP信号通路活性有关吗?

背景:前期研究证实脉冲电磁场对前软骨干细胞增殖具有促进作用,但其作用机制不明确。目的:进一步探讨脉冲电磁场对前软骨干细胞增殖分化的影响,并观察其对前软骨干细胞Ihh/PTHrP信号通路活性的影响。方法:采用免疫磁珠分选法获取并纯化SD大鼠前软骨干细胞,使用频率为50MHz,电场强度为1mT的脉冲电磁场进行干预,0.5h/次,2次/d,干预2,4,6d后收集细胞,以不给予磁场刺激的为空白对照。通过RT-PCR法检测细胞Ⅱ型胶原和聚集蛋白聚糖的基因表达水平,再通过Western-blot法测定各组细胞印度刺猬蛋白、甲状旁腺激素相关肽蛋白的表达水平。结果与结论:RT-PCR结果显示,Ⅱ型胶原和聚集蛋白聚糖的表达随磁场刺激时间延长而增高,且经磁场刺激前软骨干细胞的聚集蛋白聚糖明显高于空白对照组(P0.05,P0.01)。Western-blot结果显示,印度豪猪蛋白及甲状旁腺激素相关肽蛋白表达均随磁场刺激时间的延长增加,不同时间磁场刺激组印度刺猬蛋白表达高于空白对照组(P0.01);甲状旁腺激素相关肽的表达量也随之上升,但当磁场刺激4,6d后的甲状旁腺激素相关肽蛋白表达与空白对照组差异有显著性意义(P0.05,P0.01)。提示强度为1mT,频率为50MHz的脉冲电磁场能促进前软骨干细胞向成熟软骨细胞增殖分化,其作用机制可能与改变Ihh/PTHrP信号通路活性有关。     

可调空间聚焦低频脉冲电磁场发生装置研制

目的:研制空间聚焦和频率强度可调的低频脉冲电磁场(Pulsed Electromagnetic Fields,PEMF)发生装置。方法:采用以单片机STC89C52为基础的智能可调低频脉冲信号发生器产生不同频率占空比的低频脉冲信号;该信号经预放大滤波后,由PA19构成的功率放大电路进行放大,驱动后级可调空间聚焦电磁场发射架;PEMF强度和空间分布通过特斯拉计HT108进行测量。结果:PEMF发生装置能够产生频率0~2 k Hz、占空比10%~80%和强度0~400 m T可调的PEMF,且空间聚焦效果明显。结论:PEMF发生装置具有输出PEMF各参数可调范围大、电磁场聚焦范围空间可调等优点,适合用于电磁场非热生物效应研究。     

Human intelligence: the brain,an electromagnetic system synchronised by the Schumann Resonance signal

The human brain is a biological organ. On one hand it is soft, flexible and adaptive, but on the other hand is relatively stable and coherent with well developed intelligence. In order to retain intelligent thinking in a soft and adaptive organ there needs to be a constant, globally available, synchronization system that continuously stabilizes the brain. Rapid intelligence and reactions requires and electromagnetic signalling system, supported by a biochemical system. The Schumann Resonance signal provides a brain frequency range matching electromagnetic signal, providing the synchronization needed for intelligence.     

极低频电磁暴露对钙离子跨膜迁移的影响及机理分析

目的:研究极低频（ELF）电磁暴露对细胞钙离子跨膜迁移的影响。 方法:以人体肝癌细胞为对象,激光扫描共聚焦显微镜为检测手段,研究细胞钙离子跨膜迁移对ELF电磁暴露的响应。 结果:在磁场强度为1.78×10-7 T条件下,与对照组对比,各暴露组均对不同频率和电场强度组合的外加电磁暴露环境有响应,其中[f=16 Hz]且[EP=53 Vm]、[f=45 Hz]且[EP=53 Vm]以及[f=16 Hz]且[EP=80 Vm]的电磁暴露可使钙离子跨膜迁移量显著上升,而[f=32 Hz]且[EP=53 Vm]、[f=60 Hz]且[EP=53 Vm]、[f=16 Hz]且[EP=26 Vm]以及[f=16 Hz]且[EP=87 Vm]的电磁暴露未使钙离子跨膜迁移量显著上升。 结论:不同频率和电场强度组合的ELF电磁暴露均会引起钙离子跨膜迁移量产生变化且呈现出明显差异,这可为ELF电磁环境下生物学应用提供实验依据;注重细胞膜离子通道物理、生物特性基础上探讨ELF电磁暴露对钙离子跨膜迁移影响的机理。     

电磁场生物效应的细胞膜及蛋白激酶信号转导机制研究

环境中低强度的电磁场通常通过细胞膜将物理信号转化成生物信号,进而经细胞内信号 转导途径,尤其是蛋白激酶相关途径进行传递,最终产生生物效应的模式是可能的作用机制,也是目前 生物电磁学研究的热点之一。本文就电磁场与细胞膜及蛋白激酶相关的信号转导的研究作了综述。     

Mechanical activation and isometric oscillation in insect fibrillar muscle

Summary In isolated contractile structures of insect fibrillar muscle (DLM of Lethocerus) a quick extension causes a delayed rise of tension which is often followed by (damped) isometric oscillations. Similar phenomena may be also observed after a quick release which causes an immediate tension fall followed by a small and nearly immediate tension recovery passing into oscillation. The oscillation frequency has a temperature coefficient (Q ₁₀) of about 3.5 but depends also on the nature of the muscle (8 Hz in DLM of Lethocerus maximus at 20° C; 14 Hz in DLM of Lethocerus annulipes); it is further affected by the ATPase reaction products but not by calcium ions (range 10^–6–10^–5 M) nor by stretch, and it corresponds to the optimum myogenic oscillation frequency in driven oscillation experiments at 0.5% length change as well as to the wingbeat frequency of Lethocerus. All these findings agree with a previous hypothesis (Pringle) that myogenic oscillation — at least at low amplitude and optimal frequency — may be due to a more or less synchronized cross-bridge action. Evidence for partial cross-bridge synchronization during isometric oscillation stems from ATPase estimations in conjunction with measurements of the immediate elasticity (stiffness); these indicate that a maximal number of cross-bridges attaches almost immediately after stretch activation, and nearly in synchrony. The immediate series elasticity determined by quick releases suggests cross-bridge movements of the order 100 Å, in an oscillatory cycle. It is also concluded that contraction speed but not contractile tension is dependent on the turnover frequency of cross-bridges, if, indeed, the latter is reflected in the isometric oscillation frequency.Supported by the Deutsche Forschungsgemeinschaft (Grant RU 154/3-6).     

Purkinje cell rhythmicity and synchronicity during modulation of fast cerebellar oscillation

Fast (approximately 160 Hz) cerebellar oscillation has been recently described in different models of ataxic mice, such as mice lacking calcium-binding proteins and in a mouse model of Angelman syndrome. Among them, calretinin-calbindin double knockout mice constitute the best model for evaluating fast oscillations in vivo. The cerebellum of these mice may present long-lasting episodes of very strong and stable local field potential oscillation alternating with the normal non-oscillating state. Spontaneous firing of the Purkinje cells in wild type and double knockout mice largely differs. Indeed, the Purkinje cell firing of the oscillating mutant is characterized by an increased rate and rhythmicity and by the emergence of synchronicity along the parallel fiber axis. To better understand the driving role played by these different parameters on fast cerebellar oscillation, we simultaneously recorded Purkinje cells and local field potential during the induction of general anesthesia by ketamine or pentobarbitone. Both drugs significantly increased Purkinje cell rhythmicity in the absence of oscillation, but they did not lead to Purkinje cell synchronization or to the emergence of fast oscillation. During fast oscillation episodes, ketamine abolished Purkinje cell synchronicity and inhibited fast oscillation. In contrast, pentobarbitone facilitated fast oscillation, induced and increased Purkinje cell synchronicity. We propose that fast cerebellar oscillation is due to the synchronous rhythmic firing of Purkinje cell populations and is facilitated by positive feedback whereby the oscillating field further phase-locks recruited Purkinje cells onto the same rhythmic firing pattern.     

Long-range synchronization of gamma and beta oscillations and the plasticity of excitatory and inhibitory synapses: a network model

The ability of oscillating networks to synchronize despite significant separation in space, and thus time, is of biological significance, given that human gamma activity can synchronize over distances of several millimeters to centimeters during perceptual and learning tasks. We use computer simulations of networks consisting of excitatory pyramidal cells (e-cells) and inhibitory interneurons (i-cells), modeling two tonically driven assemblies separated by large (>or=8 ms) conduction delays. The results are as follows. 1) Two assemblies separated by large conduction delays can fire synchronously at beta frequency (with i-cells firing at gamma frequency) under two timing conditions: e-cells of (say) assembly 2 are still inhibited "delay + spike generation milliseconds" after the e-cell beat of assembly 1; this means that the e-cell inhibitory postsynaptic potential (IPSP) cannot be significantly shorter than the delay (2-site effect). This implies for a given decay time constant that the interneuron --> pyramidal cell conductances must be large enough. The e-cell IPSP must last longer than the i-cell IPSP, i.e., the interneuron --> pyramidal cell conductance must be sufficiently large and the interneuron --> interneuron conductance sufficiently small (local effect). 2) We define a "long-interval doublet" as a pair of interneuron action potentials-separated by approximately "delay milliseconds"-in which a) the first spike is induced by tonic inputs and/or excitation from nearby e-cells, while b) the second spike is induced by (delayed) excitation from distant e-cells. "Long-interval population doublets" (long-interval doublets of the i-cell population) are necessary for synchronized firing in our networks. Failure to produce them leads to almost anti-phase activity at gamma frequency. 3) An (almost) anti-phase oscillation is the most stable oscillation pattern of two assemblies that are separated by axonal conduction delays of approximately one-half a gamma period (delays from 8 to 17 ms in our simulations) and that are firing at gamma frequency. 4) Two assemblies separated by large conduction delays can synchronize their activity with the help of interneuron plasticity. They can also synchronize without pyramidal cell --> pyramidal cell connections being present. The presence of pyramidal cell --> pyramidal cell connections allows, however, for synchronization if other parameters are at inappropriate values for synchronization to occur. 5) Synchronization of two assemblies separated by large conduction delays with the help of interneuron plasticity is not simply due to slowing down of the oscillation frequency. It is reached with the help of a "synchronizing-weak-beat," which induces sudden changes in the oscillation period length of the two assemblies.     

用于神经细胞实验研究的低频交变磁场发生器的研制

本文介绍了一种用于神经细胞实验研究的低频磁场波形发生器。目的：为低频磁场辐照与肿瘤实验提供工具。材料与方法：采用单片机控制，用户手动选择参数。输出一定波形，强度和占空比的信号，经功放电路放大后得到低频磁场。本文将详细讨论仪器中波形发生的部分。结果：本仪器磁场强度最高可达100mT，频率0-500Hz。结论：仪器完全满足实验需要。     

swLORETA: a novel approach to robust source localization and synchronization tomography

Standardized low-resolution brain electromagnetic tomography (sLORETA) is a widely used technique for source localization. However, this technique still has some limitations, especially under realistic noisy conditions and in the case of deep sources. To overcome these problems, we present here swLORETA, an improved version of sLORETA, obtained by incorporating a singular value decomposition-based lead field weighting. We show that the precision of the source localization can further be improved by a tomographic phase synchronization analysis based on swLORETA. The phase synchronization analysis turns out to be superior to a standard linear coherence analysis, since the latter cannot distinguish between real phase locking and signal mixing.     

相位同步性分析方法在癫痫研究中的应用

同步振荡是神经系统中普遍存在的一种现象,是理解大脑信息处理机制的重要切入点,不同频段的同步现象能够编码不同的刺激信息.癫痫是由大脑整体或局部整合的不足或异常造成的,同步振荡现象在癫痫的发生过程中扮演了重要的角色.本文介绍了应用希尔伯特变换和小波变换提取脑电的瞬时相位方法,介绍了脑电相位同步性的相干分析、相位同步指数和香侬熵法,以及这些方法在癫痫同步放电研究中的应用,为提取癫痫患者大脑功能的信息和更深入地探索癫痫发作的机理提供了理论依据.