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Magnetic Therapy Research: Functional Mechanisms

 

Mechanism of action of moderate-intensity static magnetic fields on biological systems.

Rosen AD.

Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA. arosen@bilbo.bio.purdue.edu

There is substantial evidence indicating that moderate-intensity static magnetic fields (SMF) are capable of influencing a number of biological systems, particularly those whose function is closely linked to the properties of membrane channels. Most of the reported moderate SMF effects may be explained on the basis of alterations in membrane calcium ion flux. The mechanism suggested to explain these effects is based on the diamagnetic anisitropic properties of membrane phospholipids. It is proposed that reorientation of these molecules during moderate SMF exposure will result in the deformation of imbedded ion channels, thereby altering their activation kinetics. Channel inactivation would not be expected to be influenced by these fields because this mechanism is not located within the intramembraneous portion of the channel. Patch-clamp studies of calcium channels have provided support for this hypothesis, as well as demonstrating a temperature dependency that is understandable on the basis of the membrane thermotropic phase transition. Additional studies have demonstrated that sodium channels are similarly affected by SMFs, although to a lesser degree. These findings support the view that moderate SMF effects on biological membranes represent a general phenomenon, with some channels being more susceptible than others to membrane deformation.

Cell Biochem Biophys. 2003;39(2):163-73.

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Neuronal ion channels and their sensitivity to extremely low frequency weak electric field effects.

Mathie A, Kennard LE, Veale EL.

Biophysics Section, Department of Biological Sciences, Imperial College London, London SW7 2AZ, UK. a.mathie@imperial.ac.uk

Neuronal ion channels are gated pores whose opening and closing is usually regulated by factors such as voltage or ligands. They are often selectively permeable to ions such as sodium, potassium or calcium. Rapid signalling in neurons requires fast voltage sensitive mechanisms for closing and opening the pore. Anything that interferes with the membrane voltage can alter channel gating and comparatively small changes in the gating properties of a channel can have profound effects. Extremely low frequency electrical or magnetic fields are thought to produce, at most, microvolt changes in neuronal membrane potential. At first sight, such changes in membrane potential seem orders of magnitude too small to significantly influence neuronal signalling. However, in the central nervous system, a number of mechanisms exist which amplify signals. This may allow such small changes in membrane potential to induce significant physiological effects.

Radiat Prot Dosimetry. 2003; 106(4): 311-6.

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The microscopic nature of localization in the quantum Hall effect.

Ilani S, Martin J, Teitelbaum E, Smet JH, Mahalu D, Umansky V, Yacoby A.

[1] Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100, Israel [2] Present address: Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA.

The quantum Hall effect arises from the interplay between localized and extended states that form when electrons, confined to two dimensions, are subject to a perpendicular magnetic field. The effect involves exact quantization of all the electronic transport properties owing to particle localization. In the conventional theory of the quantum Hall effect, strong-field localization is associated with a single-particle drift motion of electrons along contours of constant disorder potential. Transport experiments that probe the extended states in the transition regions between quantum Hall phases have been used to test both the theory and its implications for quantum Hall phase transitions. Although several experiments on highly disordered samples have affirmed the validity of the single-particle picture, other experiments and some recent theories have found deviations from the predicted universal behaviour. Here we use a scanning single-electron transistor to probe the individual localized states, which we find to be strikingly different from the predictions of single-particle theory. The states are mainly determined by Coulomb interactions, and appear only when quantization of kinetic energy limits the screening ability of electrons. We conclude that the quantum Hall effect has a greater diversity of regimes and phase transitions than predicted by the single-particle framework. Our experiments suggest a unified picture of localization in which the single-particle model is valid only in the limit of strong disorder.

Nature. 2004 Jan 22; 427(6972): 328-332.

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Abnormal shift of connexin 43 gap-junction protein induced by 50 Hz electromagnetic fields in Chinese hamster lung cells.

Zeng Q, Hu G, Chiang H, Fu Y, Mao G, Lu D.

Microwave Lab., Zhejiang University School of Medicine, Hangzhou 310031, China.

OBJECTIVE: To study the effects of extremely low frequency magnetic fields(ELF MF) on the amount and localization of connexin 43(Cx43) gap-junction protein in the Chinese hamster lung(CHL) cells, and to explore the mechanism of ELF MF suppression on gap-junctional intercellular communication(GJIC).

METHODS: The cells were irradiated for 24 h with 50 Hz sinusoidal magnetic field at 0.8 mT without or with 12-O-tetrade-canoylphorbol-3-acetate(TPA), 5 ng/ml for 1 h. The localization of Cx43 proteins were performed by indirect immunofluorescence histochemical analysis and detected by confocal microscopy. The second experiment was conducted to examine the quantity of Cx43 proteins level in nuclei or cytoplasm and detected by Western blotting analysis.

RESULTS: The cells exposed to TPA for 1 h displayed less bright labelled spots in the regions of intercellular junction than the normal cells. Most of Cx43 labelled spots occurred in the cytoplasm and aggregated near the nuclei. At the same time, the amount of Cx43 protein in cytoplasm were increased[(2.03 +/- 0.89) in ELF group, (2.43 +/- 0.82) in TPA group] as compared to normal control(1.04 +/- 0.17) (P < 0.01).

CONCLUSION: Inhibition on GJIC function by ELF MF alone or combined with TPA may be related with the shift of Cx43 from the regions of intercellular junction to the cytoplasm.

Zhonghua Lao Dong Wei Sheng Zhi Ye Bing Za Zhi. 2002 Aug; 20(4): 260-2.

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Physical mechanisms in neuroelectromagnetic therapies.

Liboff AR, Jenrow KA.

Department of Physics, Oakland University, Rochester, MI 48309, USA. liboff@oakland.edu

Physical parameters that are used to characterize different types of electromagnetic devices used in neurotherapy can include power, frequency, carrier frequency, current, magnetic field intensity, and whether an application is primarily electric or primarily magnetic. Currents can range from tens of microamperes to hundreds of milliamperes, magnetic fields from tens of microtesla to more than one tesla, and frequencies from a few Hz to more than 50 GHz. A division into three device categories is proposed, based on the current applied and the specificity of the therapeutic signal. Two research areas have great potential for new neuroelectromagnetic strategies. Studies of endogenous neural oscillatory states suggest using external fields to reinforce or inhibit such states. Also, various independent groups have reported that weak magnetic fields, in particular ion cyclotron resonance fields, are capable of sharply altering behavior in rats.

NeuroRehabilitation. 2002;17(1):9-22.

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A mechanism for action of extremely low frequency electromagnetic fields on biological systems.

Balcavage WX, Alvager T, Swez J, Goff CW, Fox MT, Abdullyava S, King MW.

Indiana University School of Medicine, Indiana State University, Terre Haute 47809, USA.

This report outlines a simple mechanism, based on the Hall Effect, by which static and low frequency (50-60 Hz) pulsed electromagnetic fields (PEMFs) can modify cation flow across biological membranes and alter cell metabolism. We show that magnetic fields commonly found in the environment can be expected to cause biologically significant interactions between transported cations and basic domains of cation channel proteins. We calculate that these interactions generate forces of a magnitude similar to those created by normal transmembrane voltage changes known to gate cation channels. Thus PEMFs are shown to have the potential of regulating flow through cation channels, changing the steady state concentrations of cellular cations and thus the metabolic processes dependent on cation concentrations.

Biochem Biophys Res Commun. 1996 May 15;222(2):374-8.

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A proposed mechanism for the action of strong static magnetic fields on biomembranes.

Rosen AD.

Department of Neurology, School of Medicine, State University of New York at Stony Brook 11794-8121.

Experimental studies have demonstrated a temperature dependent effect by strong static magnetic fields on synaptic function. It is proposed that these findings may be explained by the diamagnetic properties of membrane phospholipids. The change in diamagnetic anisotropy coincidental with membrane thermotropic phase transition is responsible for the temperature dependence of this phenomenon and provides insight into the mechanism of action of these fields. At the prephase transition temperature highly diamagnetic anisotropic gel phase domains exist within a more fluid liquid-crystal phase. The partial magnetic reorientation of these domains results in membrane distortion and, thereby, functional impairment of contiguous ion specific channels. This mechanism adequately explains observations of the effects of static magnetic fields both on the central nervous system and at the neuromuscular junction. It is suggested that the same mechanism may be operative in other biosystems.

Int J Neurosci. 1993 Nov;73(1-2):115-9.

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