Electromagnetic fields in medicine – The state of art

ABSTRACT

Introduction: Intense development of methods belonging to physical medicine has been noted recently. There are treatment methods, which in many cases lead to reduction treatment time and positively influence on quality of life treatment patients. Research implications: The present physical medicine systematically extends their therapeutic possibilities. This above applies to illnesses and injuries of locomotor system, diseases affecting of soft tissues, as well as chronic wounds. The aim of the study: The evidence on this are the results of basic and clinical examinations relating the practical use of electromagnetic fields in medicine. Originality: In this work the authors introduced the procedure using the current knowledge relating to physical characteristic and biological effects of the magnetic fields. In the work the following methods were used: static magnetic fields, spatial magnetic fields, the variable magnetic fields both with laser therapy (magnetolaserotherapy) and variable magnetic fields both with light optical non-laser (magnetoledtherapy) talked.     

Modulation of phospholipase A2 by electrostatic fields and dipole potential of glycosphingolipids in monolayers

Phospholipase A2 activity against mixed monolayers of dilauroylphosphatidic acid or dilauroylphosphatidylcholine with glycosphingolipids can be reversibly modulated by external constant electrostatic fields. The changes of enzymatic activity are correlated to the depolarization or hyperpolarization of the film caused by specific dipolar properties of glycosphingolipids. Hyperpolarizing fields enhance the enzymatic activity against pure dilauroylphosphatidic acid while depolarizing fields induce a decrease of activity. Compared to the pure substrate, the interface of mixed films containing neutral glycosphingolipids or gangliosides is already partially depolarized and the magnitude of activation induced by an external hyperpolarizing field is decreased; conversely, depolarizing fields cause an increased inhibition of activity. Differing from gangliosides, sulfatides bring about a hyperpolarization of the mixed lipid monolayer and external hyperpolarizing or depolarizing fields cause enhanced activation and reduced inhibition, respectively. The effects of glycosphingolipids depend on their relative proportion in the monolayer. Results were similar with dilauroylphosphosphatidylcholine but the field effects were less than half of those found with dilauroylphosphatidic acid. Our work shows that the activity of phospholipase A2 in addition to responding reversibly to external electrostatic fields, is directly modulated by the polarity and magnitude of the lipid polar head group dipole moments.     

The strike rate index: a new index for journal quality based on journal size and the h-index of citations

Quantifying the impact of scientific research is almost always controversial, and there is a need for a uniform method that can be applied across all fields. Increasingly, however, the quantification has been summed up in the impact factor of the journal in which the work is published, which is known to show differences between fields. Here the h-index, a way to summarize an individual's highly cited work, was calculated for journals over a twenty year time span and compared to the size of the journal in four fields, Agriculture, Condensed Matter Physics, Genetics and Heredity and Mathematical Physics. There is a linear log-log relationship between the h-index and the size of the journal: the larger the journal, the more likely it is to have a high h-index. The four fields cannot be separated from each other suggesting that this relationship applies to all fields. A strike rate index (SRI) based on the log relationship of the h-index and the size of the journal shows a similar distribution in the four fields, with similar thresholds for quality, allowing journals across diverse fields to be compared to each other. The SRI explains more than four times the variation in citation counts compared to the impact factor.     

Effects of oscillatory electric fields on internal membranes: an analytical model

We derive an analytical model of the potential differences induced across plasma and internal organelle membranes in suspended cells exposed to oscillatory electric fields. Multiple shells are modeled using iterative applications of the single-shell calculation with mobile charges. This work is motivated, in part, by recent results suggesting the ability to use alternating current (ac) fields to noninvasively monitor enzyme activity within internal membranes, particularly the mitochondrial electron transport chain. Previous work, on induced transmembrane voltages in cells subjected to ac fields, has mainly been limited to oscillatory potentials across the plasma membrane. Here we first develop a three-membrane model, consisting of a plasma membrane surrounding inner and outer membranes representing an internal organelle, such as a mitochondrion. Frequency-dependent transmembrane potentials are modeled for spherical, weakly conducting membrane shells enclosing a conductive cytoplasm surrounding an idealized internal organelle. We then use a two-shell model to simulate induced ac membrane potentials of a suspended isolated mitochondrion in which the outer membrane is usually much more permeable than the inner membrane.     

Behavioral Studies with Electromagnetic Fields: Implications for Psychobiology

Research In the behavioral effects of non-ionizing radiation has progressed very slowly over the past twenty years. Of the little that has been done, much of it has been in imitation of Soviet work using archaic, insensitive behavioral techniques. Much of this work has been done by scientists not qualified in experimental psychology and they seem to be unaware of the elegance and sensitivity of behavioral techniques that have been developed in the United States. A critical review of the literature available, though, reveals that (1) effects are most clearly and reliably discerned when time-based schedules of reinforced behavior are used; (2) pulsed or modulated fields have more impact than CW fields, something that can be observed only if the behavioral measure is reliable and sensitive; and (3) magnetic fields may be especially potent for some species, if not all. Directions for future research are suggested.     

Is sparse and distributed the coding goal of simple cells?

The question of why the receptive fields of simple cells in the primary visual cortex are Gabor-like is a crucial one in vision research. Many research efforts (Olshausen and Field 1996, 1997; van Hateren and Ruderman 1998; van Hateren and van der Schaaf 1998) that yield a set of localized, oriented, and bandpass Gabor-like receptive fields believe that sparse and distributed is the coding goal of simple cells. This paper investigates a more general coding strategy that measures equally any departure from normality in the simple cells responses. That is, we investigate the possibility that highly kurtotic response histograms may result if simple cells explicitly seek, not maximally kurtotic, but rather maximally non-Gaussian response histograms to natural images. It is found that, under this coding strategy, the simulations produce a majority of localized, oriented, bandpass (Gabor-like) receptive fields. Some receptive fields, however, are spatially distributed and show little oriented structure. Nearly all receptive fields, regardless of whether they are Gabor-like or non-Gabor-like, yield highly kurtotic response histograms to natural images. Thus, in seeking maximally non-Gaussian response histograms, receptive fields spontaneously yield highly kurtotic histograms. The presence in our ensemble of nonlocalized, nonoriented receptive fields may be due to the artificial requirement that receptive fields be orthonormal. We conclude that the high kurtoses observed in the response histograms of simple-cell receptive fields to natural images may reflect a property of natural images themselves rather than an explicit coding goal used to structure simple-cell receptive fields.Acknowledgement This work was supported by the US Office of Naval Research under agreement number N68936-00-2-0002.     

Biological effects of exposure to magnetic resonance imaging: an overview

The literature on biological effects of magnetic and electromagnetic fields commonly utilized in magnetic resonance imaging systems is surveyed here. After an introduction on the basic principles of magnetic resonance imaging and the electric and magnetic properties of biological tissues, the basic phenomena to understand the bio-effects are described in classical terms. Values of field strengths and frequencies commonly utilized in these diagnostic systems are reported in order to allow the integration of the specific literature on the bio-effects produced by magnetic resonance systems with the vast literature concerning the bio-effects produced by electromagnetic fields. This work gives an overview of the findings about the safety concerns of exposure to static magnetic fields, radio-frequency fields, and time varying magnetic field gradients, focusing primarily on the physics of the interactions between these electromagnetic fields and biological matter. The scientific literature is summarized, integrated, and critically analyzed with the help of authoritative reviews by recognized experts, international safety guidelines are also cited.     

The adenosine triphosphate content of cysts of Globodera pallida and G. rostochiensis as a possible quantitative estimate of field populations

A rapid method is described for estimating the number of juveniles of Globodera pallida and G. rostochiensis in cysts collected from field soils. The technique uses a photometer to measure the adenosine triphosphate (ATP) content of the cysts by bioluminescence. Results for ten to twelve soil samples of 100 g taken from each of four fields showed that the number of juveniles that emerged when the samples were placed in potato root diffusate was significantly related to ATP content of a second series of cyst samples from these fields. Cysts from one field gave a higher ATP content per hatched juvenile than was recorded for the remaining three fields. There are several, untested, explanations of this discrepancy, but some evidence suggests that the hatching test and not the ATP method may have given an unreliable estimate of the viable egg content of cysts from this field. Further work may result in an enhanced precision and increased rapidity in estimating field populations of cyst nematodes by this technique.     

Small field correction factors for the IBA Razor

The IBA Razor diode supersedes the IBA SFD and is intended for use in small fields. However, its behaviour in small fields has not yet been quantified. In this work, we examine the response of the Razor diode against the air core scintillation dosimeter (FOD) and Gafchromic film in photon beams from three Varian linac beams. Fields between 4 mm and 30 mm in width were measured, both with and without a flattening filter and at two energies. The Razor exhibited an over-response of up to 4.5% for MLC collimated fields and 7.1% for stereotactic cone collimated fields. The presence of the flattening filter altered the over-response by up to 1.5%. The small field correction factors are tabulated and agree with the mathematical relation of Liu et al. (2014). Four samples of the Razor were used, two having received a significant prior dose. The correction factors for the four samples differed and may depend on their dose history.     

Towards MR-guided electron therapy: Measurement and simulation of clinical electron beams in magnetic fields

PurposeIn the current era of MRI-linac radiotherapy, dose optimization with arbitrary dose distributions is a reality. For the first time, we present new and targeted experiments and modeling to aid in evaluating the potential dose improvements offered with an electron beam mode during MRI-linac radiotherapy.MethodsSmall collimated (1 cm diameter and 1.5 × 1.5 cm² square) electron beams (6, 12 and 20 MeV) from a clinical linear accelerator (Varian Clinac 2100C) are incident perpendicular and parallel to the strong and localized magnetic fields (0–0.7 T) generated by a permanent magnet device. Gafchromic EBT3 film is placed inside a slab phantom to measure two-dimensional dose distributions. A benchmarked and comprehensive Monte Carlo model (Geant4) is established to directly compare with experiments.ResultsWith perpendicular fields a 5% narrowing of the beam FWHM and a 10 mm reduction in the 15% isodose penetration is seen for the 20 MeV beam. In the inline setup the penumbral width is reduced by up to 20%, and a local central dose enhancement of 100% is observed. Monte Carlo simulations are in agreement with the measured dose distributions (2% or 2 mm).ConclusionA new range of experiments have been performed to offer insight into how an electron beam mode could offer additional choices in MRI-linac radiotherapy. The work extends on historic studies to bring a successful unified experimental and Monte Carlo modeling approach for studying small field electron beam dosimetry inside magnetic fields. The results suggest further work, particularly on the inline magnetic field scenario.     

ELF Noise Fields: A Review

The debate as to whether low-level electromagnetic fields can affect biological systems and in the long term cause health effects has been going on for a long time. Yet the interaction of weak electromagnetic fields (EMF) with living cells, undoubtedly a most important phenomenon, is still not well understood. The exact mechanisms by which the effects are produced have not been identified. Furthermore, it is not possible to clearly define which aspects of an EMF exposure that constitute the “dose.” One of the groups that contributed to solving this problem is the Bioelectromagnetics group at Catholic University of America (CUA), Washington, D.C. Their work has been devoted to investigating the physical parameters that are needed to obtain an effect of EMF exposure on biological systems, and also how to inhibit the effect. This is a review of their work on bioeffects caused by low-level EMF, their dependence on coherence time, constancy, spatial averaging, and also how the effects can be modified by an applied ELF noise magnetic field. The group has been using early chick embryos, and L929 and Daudi cells as their main experimental systems. The review also covers the work of other groups on low-level effects and the inhibition of the effects with an applied noise field. The group at CUA has shown that biological effects can be found after exposure to low-level ELF and RF electromagnetic fields, and when effects are observed, applying an ELF magnetic noise field inhibits the effects. Also, other research groups have tried to replicate the studies from the CUA group, or to apply EMF noise to suppress EMF-induced effects. Replications of the CUA effects have not always been successful. However, in all cases where the noise field has been applied to prevent an observed effect, it has been successful in eliminating the effect.     

Functional imaging reveals numerous fields in the monkey auditory cortex

Anatomical studies propose that the primate auditory cortex contains more fields than have actually been functionally confirmed or described. Spatially resolved functional magnetic resonance imaging (fMRI) with carefully designed acoustical stimulation could be ideally suited to extend our understanding of the processing within these fields. However, after numerous experiments in humans, many auditory fields remain poorly characterized. Imaging the macaque monkey is of particular interest as these species have a richer set of anatomical and neurophysiological data to clarify the source of the imaged activity. We functionally mapped the auditory cortex of behaving and of anesthetized macaque monkeys with high resolution fMRI. By optimizing our imaging and stimulation procedures, we obtained robust activity throughout auditory cortex using tonal and band-passed noise sounds. Then, by varying the frequency content of the sounds, spatially specific activity patterns were observed over this region. As a result, the activity patterns could be assigned to many auditory cortical fields, including those whose functional properties were previously undescribed. The results provide an extensive functional tessellation of the macaque auditory cortex and suggest that 11 fields contain neurons tuned for the frequency of sounds. This study provides functional support for a model where three fields in primary auditory cortex are surrounded by eight neighboring “belt” fields in non-primary auditory cortex. The findings can now guide neurophysiological recordings in the monkey to expand our understanding of the processing within these fields. Additionally, this work will improve fMRI investigations of the human auditory cortex.     

<Emphasis Type="Italic">Xenopu</Emphasis>s Embryos and ES Cells as Tools for Studies of Developmental Biology

Nearly 20 years ago Professor Katsuhiko Mikoshiba led me to an exciting world of IP₃-Ca²⁺ signaling, we embarked on the role of IP₃-Ca²⁺ signaling on fertilization, early cell cycle progression, and body axis formation. I was fully enchanted by the world of basic science, particularly developmental biology. It is a great pleasure to contribute a paper to this special issue of Neurochemical Research honoring Professor Katsuhiko Mikoshiba. Many of the former lab members are now working in a wide range of fields, both inside or outside the fields of Neurochemical research. I am one of those who are working in a different field. Therefore, it seems fitting here to first write about our former work with IP3 receptor, and then introduce our recent works.     

Three-dimensional quantitative structure–farnesyltransferase inhibition analysis for some diaminobenzophenones

A 3D-QSAR investigation of 95 diaminobenzophenone yeast farnesyltransferase (FT) inhibitors selected from the work of Schlitzer et al. showed that steric, electrostatic, and hydrophobic properties play key roles in the bioactivity of the series. A CoMFA/CoMSIA combined model using the steric and electrostatic fields of CoMFA together with the hydrophobic field of CoMSIA showed significant improvement in prediction compared with the CoMFA steric and electrostatic fields model. The similarity of the 3D-QSAR field maps for yeast FT inhibition activity (from this work) and for antimalarial activity data (from previous work) and the correlation between those activities are discussed.     

Finding A Seat at the Table Together: Recommendations for Improving Collaboration between Social Work and Bioethics

Social work and bioethics are fields deeply committed to cross‐disciplinary collaboration to do their respective work. While scholars and practitioners from both fields share a commitment to social justice and to respecting the dignity, integrity and the worth of all persons, the overlap between the fields, including shared values, has received little attention. The purpose of this article is to describe the ways in which greater collaboration between the two fields can broaden their scope, enrich their scholarship, and better ground their practice. We describe the potential for realizing such benefits in two areas – health care ethics consultation and social inequalities in health – arguing that the fields both complement and challenge one another, making them ideal partners for the interdisciplinary inquiry and problem‐solving so often called for today in health and health care.     

Functional Imaging of Chemically Active Surfaces with Optical Reporter Microbeads

We have developed a novel approach to allow for continuous imaging of concentration fields that evolve at surfaces due to release, uptake, and mass transport of molecules, without significant interference of the concentration fields by the chemical imaging itself. The technique utilizes optical “reporter” microbeads immobilized in a thin layer of transparent and inert hydrogel on top of the surface. The hydrogel has minimal density and therefore diffusion in and across it is like in water. Imaging the immobilized microbeads over time provides quantitative concentration measurements at each location where an optical reporter resides. Using image analysis in post-processing these spatially discrete measurements can be transformed into contiguous maps of the dynamic concentration field across the entire surface. If the microbeads are small enough relative to the dimensions of the region of interest and sparsely applied then chemical imaging will not noticeably affect the evolution of concentration fields. In this work colorimetric optode microbeads a few micrometers in diameter were used to image surface concentration distributions on the millimeter scale.     

Applied DC magnetic fields cause alterations in the time of cell divisions and developmental abnormalities in early sea urchin embryos

Most work on magnetic field effects focuses on AC fields. The present study demonstrates that exposure to medium-strength (10 mT-0.1 T) static magnetic fields can alter the early embryonic development of two species of sea urchin embryos. Batches of fertilized eggs from two species of urchin were exposed to fields produced by permanent magnets. Samples of the continuous cultures were scored for the timing of the first two cell divisions, time of hatching, and incidence of exogastrulation. It was found that static fields delay the onset of mitosis in both species by an amount dependent on the exposure timing relative to fertilization. The exposure time that caused the maximum effect differed between the two species. Thirty millitesla fields, but not 15 mT fields, caused an eightfold increase in the incidence of exogastrulation in Lytechinus pictus, whereas neither of these fields produced exogastrulation in Strongylocentrotus purpuratus. Bioelectromagnetics 18:255–263, 1997. © 1997 Wiley-Liss, Inc.     

Extremely-Low Frequency Magnetic Field Effects on Sulfate Reducing Bacteria Viability

50?Hz magnetic fields effects on Sulfate Reducing Bacteria (SRB) viability were studied by colony forming units (CFU) counting. We found a 15% decrease of CFU number after magnetic field exposure (B=7.1?mT, f=50?Hz, t=24?min) compared to the control samples. These results are in good agreement with our previous work on other bacterial strains. The magnetic field effects on SRB are relatively large for small magnetic fields. The data correlations have been subjected to a simple physical chemical analysis, yielding surprisingly large estimates for the characteristic magnetic reaction susceptibility, even when the entire bacterium is assumed to be the direct target of interaction of the magnetic ac fields for the exposures in the time range from 3–24?min.     

Recent Progress in the Research Field of Neuropharmacology in China

In recent years, Chinese neuropharmacologists have done a lot of basic and practical work in neuropharmacology, especially in the fields of pain, drug dependence, depression, Alzheimer’s disease, schizophrenia, having obtained some exciting results that are of great significance for the development of neuropharmacology. Here I would like to review recent progress in the research fields of neuropharmacology in China.     

Magnetic induction at 60 Hz in the human heart: a comparison between the in situ and isolated scenarios

Numerical modelling is used to estimate the electric fields and currents induced in the human heart and associated major blood vessels by 60 Hz external magnetic fields. The modelling is accomplished using a scalar-potential finite-difference code applied to a 3.6-mm resolution voxel-based model of the whole human body. The main goal of the present work is a comparison between the induced field levels in the heart located in situ and in isolation. This information is of value in assessing any health risks due to such fields, given that some existing protection standards consider the heart as an isolated conducting body. It is shown that the field levels differ significantly between these two scenarios. Consequently, data from more realistic and detailed numerical studies are required for the development of reliable standards.