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1.
Except for relatively few polarity reversals the magnitude of the magnetic dipole moment of the earth has remained constant since life first began, allowing evolutionary processes to integrate the geomagnetic field (GMF) into several biological functions. One of these, bearing the classical signature of an ion cyclotron resonance (ICR)-like interaction, results in biological change associated with enhanced proton transport. The wide range of cation masses over which this effect is found suggest a fundamental biological dependence on the GMF, one that functions equally well for electric as well as magnetic fields. Such generalization of ICR requires two things: transparency of tissues to the GMF and suitably tuned ELF resonant magnetic or electric fields. To complement the widely reported ICR responses to applied AC magnetic fields, we hypothesize the existence of weak endogenous ICR electric field oscillations within the cell. This equivalence implies that even in the absence of applied AC magnetic fields, biological systems will exhibit intrinsic GMF-dependent ion cyclotron resonance intracellular interactions. Many ICR effects that have been reported appear as antagonist pairs suggesting that the characteristics of the GMF have not only been incorporated into the genome but also appear to function in an endocrine-like manner.  相似文献   

2.
Some magnetobiological problems of orbital (in the geomagnetic field--GMF) and interplanetary (in hypomagnetic conditions) flights are considered. The influence of electromagnetic fields (EMF) created by systems and equipment of the space vehicle (SV) are touched also. A level of the geomagnetic field (GMF) onboard during the orbital flights is discussed. Its periodic variations onboard owing to movement of SV on an orbit are analyzed. The reader's attention in attracted to the papers by R.M. Baevsky et al. in which the influence of magnetic storms and periodic variations of GMS on the cardiovascular system of astronauts onboard are shown. Possible ways and mechanisms of the influence are discussed. The wrong assertions in a number of works namely that at orbital flights an appreciable electrical field is induced in an organism of an astronaut in a space-craft and the electrical field may by responsible for some biological impacts are analyzed. The situation at the future in the terplanetary flights (for example Martian missions) when a crew and biological objects for a long time will be in the interplanetary magnetic field (by several orders less then GMF) is considered. As applied to the flights the opportunities of generation onboard the "artificial" GMF are outlined. The ensuing biological and technical questions are discussed.  相似文献   

3.
Weak magnetic and electromagnetic fields affect physiological processes in animals, plants, and microorganisms. Ion cyclotron resonance (ICR) is discussed as one of the sensitive mechanisms, which enable perception of the geomagnetic field and its orientation. Numerous biological effects are observed involving several small ions, showing windows of predicted frequencies and intensities. The pioneering work of Guiliano Preparata and Emilio Del Giudice using quantum electrodynamics showed that spontaneously originating coherent regions in water facilitate ICR effects at incoherent water phase boundaries. Here we examine the ICR response of the calcium ion (Ca2+), crucial for many life processes. We use an aqueous solution containing the biologically ubiquitous membrane lipid L-α-phosphatidylcholine that serves as a biomimetic proxy for dynamic light scattering (DLS) and nonlinear dielectric spectroscopy (NLDS) measurements. One notable result is that this system approaches a new equilibrium upon addition of calcium by means of the oscillatory Belousov–Zhabotinsky chemical reaction, oscillations are significantly reduced under Ca2+ ICR application. Secondly an “oscillator” of calcium ions appears to be able to itself couple coherently and predictably to large-scale coherent regions in water. This system appears able to regulate ion fluxes in response to very weak environmental electromagnetic fields.  相似文献   

4.
We consider the possibility that DC magnetic fields can interact in a resonant manner with endogenous AC electric fields in biological systems. Intrinsic electric-field ion cyclotron resonance (ICR) interactions would be more physically credible than models based on external AC magnetic fields and might be expected as an evolutionary response to the long-term constancy of the geomagnetic field. Bioelectromagnetics 17:85–87, 1997. © 1997 Wiley-Liss, Inc.  相似文献   

5.
A systematic procedure for analyzing the physical processes that govern ICR heating in systems for ion separation is developed. The procedure is based on an analytic model of an rf antenna generating rf fields within a plasma column in a magnetic field and includes such issues as the calculation of rf fields, examination of the ICR interaction of ions with these fields, and determination of the distribution function of the ion flow at the exit from the ICR heating system. It is shown that, even in ICR heating systems with easily achievable parameter values, ions with appreciably different masses can be efficiently separated by energy.  相似文献   

6.
It is proposed that the avian magnetic compass depends on the angle between the horizontal component B(h) of the geomagnetic field (GMF) and E(r), the radial electric field distribution generated by gamma-oscillations within the optic tectum (TeO). We hypothesize that the orientation of the brain relative to B(h) is perceived as a set of electric field ion cyclotron resonance (ICR) frequencies that are distributed in spatially recognizeable regions within the TeO. For typical GMF intensities, the expected ICR frequencies fall within the 20-50 Hz range of gamma-oscillation frequencies observed during visual stimulation. The model builds on the fact that the superficial lamina of the TeO receive signals from the retina that spatially map the visual field. The ICR frequencies are recruited from the local wide-band gamma-oscillations and are superposed on the tectum for interpretation along with other sensory data. As a first approximation, our analysis is restricted to the medial horizontal plane of the TeO. For the bird to fly in a preferred, previously mapped direction relative to B(h), it hunts for that orientation that positions the frequency maxima at appropriate locations on the TeO. This condition can be maintained even as B(h) varies with geomagnetic latitude during the course of long-distance flights. The magnetovisual coordinate system (straight phi, omega) overlaying the two halves of the tectal surface in a nonsymmetric way may imply an additional orienting function for the TeO over and above that of a simple compass (e.g., homing navigation as distinct from migrational navigation).  相似文献   

7.
If it is more fundamental to formulate biological expression in terms of electromagnetic fields, does this also imply that living things are especially sensitive to the external electromagnetic environment? Specifically, we examine possible genomic effects due to reversals of the geomagnetic field. To maintain sensitivity following a reversal, the Wiltschko hypothesis for the avian magnetic compass can be subsumed under an NB imprinting paradigm, where N is the horizontal vector pointing to magnetic north and B the geomagnetic field vector. Even with a compass that is invariant under reversals, there are nevertheless potential difficulties due to discontinuities in the magnitude of the field during the transition between one chron and the next. Indeed, transitions may be one reason for other-than-magnetic avian auxiliary compasses. Additional problems may also arise during transitions because of high rates of change in B. However, the largest reported dB/dt (Steens Mountain event) is estimated at 1 /u.T/day, seemingly too small to induce significant Faraday current density. Reversals may have also helped determine the nature of the interaction mechanism between GMF and living systems. Mechanisms based on fixed magnetic moments may not be capable of adapting to the reversal process. A better case can be made for an ion cyclotron resonance interaction. Direct involvement in the cell-signaling activities of biological ions would provide such flexibility, and also point to a broader role for the GMF in modulating CNS function than merely to provide orientation.  相似文献   

8.
The Earth's geomagnetic field (GMF) is known to act as a sensory cue for magnetoreceptive animals such as birds, sea turtles, and butterflies in long‐distance migration, as well as in flies, cockroaches, and cattle in short‐distance movement or body alignment. Despite a wealth of information, the way that GMF components are used and the functional modality of the magnetic sense are not clear. A GMF component, declination, has never been proven to be a sensory cue in a defined biological context. Here, we show that declination acts as a compass for horizontal food foraging in fruit flies. In an open‐field test, adopting the food conditioning paradigm, food‐trained flies significantly orientated toward the food direction under ambient GMF and under eastward‐turned magnetic field in the absence of other sensory cues. Moreover, a declination change within the natural range, by alteration only of either the east–west or north–south component of the GMF, produced significant orientation of the trained flies, indicating that they can detect and use the difference in these horizontal GMF components. This study proves that declination difference can be used for horizontal foraging, and suggests that flies have been evolutionarily adapted to incorporate a declination compass into their multi‐modal sensorimotor system.  相似文献   

9.
Spreading evidence suggests that geomagnetic field (GMF) modulates artificial magnetic fields biological effect and associated with increased cardiovascular morbidity. To explore the underlying physiological mechanism we studied 350 mT static magnetic field (SMF) effect on arterial baroreflex-mediated skin microcirculatory response in conjunction with actual geomagnetic activity, reflected by K and K p indices. Fourteen experiments were performed in rabbits sedated by pentobarbital infusion (5 mg/kg/h). Mean femoral artery blood pressure, heart rate, and the ear lobe skin microcirculatory blood flow, measured by microphotoelectric plethysmogram (MPPG), were simultaneously recorded before and after 40 min of NdFeB magnets local exposure to sinocarotid baroreceptors. Arterial baroreflex sensitivity (BRS) was estimated from heart rate/blood pressure response to intravenous bolus injections of nitroprusside and phenylephrine. We found a significant positive correlation between SMF-induced increase in BRS and increment in microvascular blood flow (ΔBRS with ΔMPPG, r=0.7, p<0.009) indicated the participation of the arterial baroreflex in the regulation of the microcirculation and its enhancement after SMF exposure. Geomagnetic disturbance, as opposed to SMF, decreased both microcirculation and BRS, and counteracted SMF-induced increment in microcirculatory blood flow (K-index with ΔMPPG; r s=−0.55, p<0.041). GMF probably affected central baroreflex pathways, diminishing SMF direct stimulatory effect on sinocarotid baroreceptors and on baroreflex-mediated vasodilatatory response. The results herein may thus point to arterial baroreflex as a possible physiological mechanism for magnetic-field cardiovascular effect. It seems that geomagnetic disturbance modifies artificial magnetic fields biological effect and should be taken into consideration in the assessment of the final effect. An erratum to this article can be found at  相似文献   

10.
Experiments on the effects of extremely-low-frequency (ELF) electric and magnetic fields on cells of the immune system, T-lymphocytes in particular, suggest that the external field interacts with the cell at the level of intracellular signal transduction pathways. These are directly connected with changes in the calcium-signaling processes of the cell. Based on these findings, a theoretical model for receptor-controlled cytosolic calcium oscillations and for external influences on the signal transduction pathway is presented. We discuss the possibility that the external field acts on the kinetics of the signal transduction between the activated receptors at the cell membrane and the G-proteins. It is shown that, depending on the specific combination of cell internal biochemical and external physical parameters, entirely different responses of the cell can occur. We compare the effects of a coherent (periodic) modulation and of incoherent perturbations (noise). The model and the calculations are based on the theory of self-sustained, nonlinear oscillators. It is argued that these systems form an ideal basis for information-encoding processes in biological systems. © 1995 Wiley-Liss, Inc.  相似文献   

11.
We have previously reported that environmental-level magnetic fields (1.2 μT [12 milligauss], 60 Hz) block the growth inhibition of the hormone melatonin (10−9 M) on MCF-7 human breast cancer cells in vitro. We now report that the same 1.2 μT, 60 Hz magnetic fields significantly block the growth inhibitory action of pharmacological levels of tamoxifen (10−7 M). In biophysical studies we have taken advantage of Faraday's Law of Current Induction and tested whether the 1.2 μT magnetic field or the associated induced electric field is responsible for this field effect on melatonin and tamoxifen. We observe that the magnetic field component is associated with the field blocking effect on melatonin and tamoxifen function. To our knowledge the tamoxifen studies represent the first experimental evidence for an environmental-level magnetic field modification of drug interaction with human breast cancer cells. Together, these findings provide support to the theory that environmental-level magnetic fields can act to modify the action of a drug or hormone on regulation of cell proliferation. Melatonin and tamoxifen may act through different biological pathways to down-regulate cell growth, and further studies are required to identify a specific biological site of interaction for the 1.2 μT magnetic field. Bioelectromagnetics 18:555–562, 1997. Published 1997 Wiley-Liss, Inc.
  • 1 This article is a US Government work and, as such, is in the public domain in the United States of America.
  •   相似文献   

    12.
    13.
    The purpose of the work was to further investigate the effect of zero magnetic field (ZMF) on the concentration of ions in the human blood compared to the effect of the normal geomagnetic field (GMF). We have investigated the total Zn and Cu concentrations in the blood serum during in vitro aging of blood. The investigation was carried out both on blood from healthy donors as well as from chronic bronchial asthma (BA) patients. Blood samples were kept for 48 hours in a Helmholtz coil compensating system to remove the static component of the geomagnetic field, at room temperature. We found that zinc concentrations in the plasma were not significantly influenced by the exposure to ZMF compared to GMF for both healthy and pathological samples. In contrast, copper concentration was found to be significantly sensitive to the magnetic environment. Healthy blood showed a slight loss of copper from the blood serum in GMF, which further increased in ZMF. BA pathology is characterized by four distinct types of disease, which showed both qualitative and quantitative distinctive sensitivity to the magnetic environment, as compared to healthy blood. The aging effect appeared to be slowed down for most of the BA types of pathologies. These results point to the sensitivity of ion binding to serum proteins and/or transport through cell membranes in the magnetic environment, in our case in the absence of the normal geomagnetic field.  相似文献   

    14.
    Pulsed electromagnetic fields (PEMFs) have been used extensively in bone fracture repairs and wound healing. It is accepted that the induced electric field is the dose metric. The mechanisms of interaction between weak magnetic fields and biological systems present more ambiguity than that of PEMFs since weak electric currents induced by PEMFs are believed to mediate the healing process, which are absent in magnetic fields. The present study examines the response of human umbilical vein endothelial cells to weak static magnetic fields. We investigated proliferation, viability, and the expression of functional parameters such as eNOS, NO, and also gene expression of VEGF under the influence of different doses of weak magnetic fields. Applications of weak magnetic fields in tissue engineering are also discussed. Static magnetic fields may open new venues of research in the field of vascular therapies by promoting endothelial cell growth and by enhancing the healing response of the endothelium. Bioelectromagnetics 31:296–301, 2010. © 2010 Wiley‐Liss, Inc.  相似文献   

    15.
    There is evidence for robust interactions of weak ELF magnetic fields with biological systems. Quite apart from the difficulties attending a proper physical basis for such interactions, an equally daunting question asks why these should even occur, given the apparent lack of comparable signals in the long-term electromagnetic environment. We suggest that the biological basis is likely to be found in the weak (~50?nT) daily swing in the geomagnetic field that results from the solar tidal force on free electrons in the upper atmosphere, a remarkably constant effect exactly in phase with the solar diurnal change. Because this magnetic change is locked into the solar-derived everyday diurnal response in living things, one can argue that it acts as a surrogate for the solar variation, and therefore plays a role in chronobiological processes. This implies that weak magnetic field interactions may have a chronodisruptive basis, homologous to the more familiar effects on the biological clock arising from sleep deprivation, phase-shift employment and light at night. It is conceivable that the widespread sensitivity of biological systems to weak ELF magnetic fields is vestigially derived from this diurnal geomagnetic effect.  相似文献   

    16.
    The Earth's geomagnetic field (GMF) is an inescapable environmental factor for plants that affects all growth and yield parameters. Both strong and weak magnetic fields (MF), as compared to the GMF, have specific roles in plant growth and development. MF technology is an eco-friendly technique that does not emit waste or generate harmful radiation, nor require any external power supply, so it can be used in sustainable modern agriculture. Thus, exposure of plants to MF is a potential affordable, reusable and safe practice for enhancing crop productivity by changing physiological and biochemical processes. However, the effect of MF on plant physiological and biochemical processes is not yet well understood. This review describes the effects of altering MF conditions (higher or lower values than the GMF) on physiological and biochemical processes of plants. The current contradictory and inconsistent outcomes from studies on varying effects of MF on plants could be related to species and/or MF exposure time and intensity. The reviewed literature suggests MF have a role in changing physiological processes, such as respiration, photosynthesis, nutrient uptake, water relations and biochemical attributes, including genes involved in ROS, antioxidants, enzymes, proteins and secondary metabolites. MF application might efficiently increase growth and yield of many crops, and as such, should be the focus for future research.  相似文献   

    17.
    Some effects of low-intensity magnetic fields on the concentration of radicals and their influence on cellular functions are reviewed. These fields have been implicated as a potential modulator of radical recombination rates. Experimental evidence has revealed a tight coupling between cellular function and radical pair chemistry from signaling pathways to damaging oxidative processes. The effects of externally applied magnetic fields on biological systems have been extensively studied, and the observed effects lack sufficient mechanistic understanding. Radical pair chemistry offers a reasonable explanation for some of the molecular effects of low-intensity magnetic fields, and changes in radical concentrations have been observed to modulate specific cellular functions. Applied external magnetic fields have been shown to induce observable cellular changes such as both inhibiting and accelerating cell growth. These and other mechanisms, such as cell membrane potential modulation, are of great interest in cancer research due to the variations between healthy and deleterious cells. Radical concentrations demonstrate similar variations and are indicative of a possible causal relationship. Radicals, therefore, present a possible mechanism for the modulation of cellular functions such as growth or regression by means of applied external magnetic fields.  相似文献   

    18.
    19.
    As they negotiate their environs, unicellular organisms adjust their swimming in response to various physical fields such as temperature, chemical gradients, and electric fields. Because of the weak magnetic properties of most biological materials, however, they do not respond to the earth's magnetic field (5 x 10(-5) Tesla) except in rare cases. Here, we show that the trajectories of Paramecium caudatum align with intense static magnetic fields >3 Tesla. Otherwise straight trajectories curve in magnetic fields and eventually orient parallel or antiparallel to the applied field direction. Neutrally buoyant immobilized paramecia also align with their long axis in the direction of the field. We model this magneto-orientation as a strictly passive, nonphysiological response to a magnetic torque exerted on the diamagnetically anisotropic components of the paramecia. We have determined the average net anisotropy of the diamagnetic susceptibility, Deltachi(p), of a whole Paramecium: Deltachi(p) = (6.7+/- 0.7) x 10(-23) m(3). We show how the measured Deltachi(p) compares to the anisotropy of the diamagnetic susceptibilities of the components in the cell. We suggest that magnetic fields can be exploited as a novel, noninvasive, quantitative means to manipulate swimming populations of unicellular organisms.  相似文献   

    20.
    The metric of prime interest in power line epidemiological studies has been AC magnetic intensity. To consider also possible geomagnetic involvement, the orientation of a long straight power line is examined relative to a uniform geomagnetic field (GMF) with dip angle α. An expression is derived for the component of the total GMF that is parallel, at an elevation β, to the circuital magnetic field that surrounds the line. This component is a function of the angles α and β, the total geomagnetic intensity BT, and the angle θ between the axis of the power line and magnetic north. Plotting these geomagnetic parameters for known leukemia residences allows one to test for possible ion cyclotron resonance or other GMF interactions. This approach, in principle, is an easy addition to existing or planned studies, because residential access is not required to obtain local values for α, β, θ, and BT. We recommend including these parameters in the design of epidemiological studies examining power line fields and childhood leukemia. © 1995 Wiley-Liss, Inc.  相似文献   

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