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Electromagnetism
Electromagnetic (EM) heating produces a higher warming rate and more uniform heating than the conventional water bath thawing method and is considered to be an effective approach especially for tissue samples thawing from vitrification.
From: Comprehensive Biotechnology (Third Edition), 2019
Related terms:
Surface Plasmon Resonance
Radiofrequency
Electromagnetic Radiation
Photon
Electric Potential
Infrared Radiation
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Electromagnetic Fields
J.R. Salvatore, in Encyclopedia of Toxicology (Third Edition), 2014
Introduction
Electromagnetic fields (EMFs) are part of the physical electromagnetic spectrum ranging from the extreme low of static magnetic fields to the extreme high of gamma rays. EMFs as discussed here focus on frequencies of 0 Hz–300 GHz, which are part of the spectrum considered to be nonionizing (Table 1). Examples of the frequencies that are part of the spectrum are electric power generation and transmission, radio frequencies (RF), and microwaves (Table 1).
Table 1. Electromagnetic spectrum
UseFrequencyNonionizing/ionizingWavelengthElectric power60 HzNonionizing106 mAM radio1 MHzNonionizingFM radio100 MHzNonionizing3 mCell phones1900 MHzNonionizing∼17 cmMicrowave oven2450 MHzNonionizingVisible light1014 HzNonionizing∼500 nmUV light1015 HzNonionizing10−7 mIonizingX-rays1018 HzIonizing10−10 mGamma rays1020 HzIonizing10−12 m
Scientific and public attention focusing on the potential human health hazards of these fields has intensified over the past 30 years, initially with the belief that electric power generation and transmission were related to the development of human leukemia; the more recent focus has been on radio frequency EMF (RF-EMF), particularly the frequencies used for cellular telephones and their transmission towers. The frequencies around and above 1015 Hz approach and surpass the energy required to cause atomic ionization. The frequency at which EMF changes from nonionizing to ionizing is not strictly defined, but approximates the upper ultraviolet frequency range (Table 1). The energy contained within the 0 Hz–300 GHz frequencies is not sufficient to create ionization or usually even a thermal change (unless this is specifically induced), and it is this fact that has driven much of the controversy over the existence of health effects of non ionizing EMF (NIEMF). Energy contained in EMF is occasionally presented as electronvolt energy, and it is helpful to use this as a general measure to compare energy presented by ionizing and nonionizing radiation. Table 2 shows representative electronvolt energies as a function of frequency.
Table 2. Approximate electronvolt energies of some EM frequencies and the relationship to ionization
Frequency useFrequency – HzeVRadio waves10610−10 (Nonionizing)Visible light10141.5–3 (Nonionizing)Ionization10–12Hydrogen atom ionization13.6X-ray1017103 (Ionizing)Gamma rays1019105 (Ionizing)
The proliferation of devices that generate NIEMF, recently cellular mobile phones and mobile smart devices, has resulted in an increase in the number of humans exposed to these fields, and an increase in the constancy of exposure to these fields. Human reaction to NIEMF exposure varies from no reaction (the majority) to what is believed to be human hypersensitivity to NIEMF, a claimed reaction to NIEMF manifested by multiple medical signs and symptoms. The terms NIEMF and nonionizing electromagnetic radiation (NIEMR) are often used interchangeably, and this can cause confusion and misunderstanding when discussing human health effects. As NIEMF moves away from its source, it is radiating (becomes NIEMR). The public perception of the term radiation is often negative, and there is a tendency to assume that all radiation and its effects, whether ionizing or nonionizing, are the same and harmful. Most individuals are familiar with the consequences of coming into contact with an electric current, which if strong enough generates an unpleasant sensation. When we are discussing electromagnetic fields here, we are generally referring to an insensible physical force.
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Value of Pulsed Electromagnetic Stimulation in Acute Scaphoid Fractures
Pascal F.W. Hannemann MD, PhD, ... Peter R.G. Brink MD, PhD, in Scaphoid Fractures: Evidence-Based Management, 2018
Main Question
What is the added value of pulsed electromagnetic field stimulation in the treatment of acute scaphoid fractures when considering the effect on fracture healing, functional outcome, and cost-effectiveness?
Current Opinion
Although PEMF bone growth stimulation has been used extensively to accelerate fracture repair, the efficacy of this technique in acute scaphoid fractures has never been thoroughly investigated. Therefore, no recommendations regarding the use of this technique for treatment of acute scaphoid fractures can be made.
Finding the Evidence
•
Cochrane search: "scaphoid" AND "Pulsed electromagnetic" OR "pulsed electromagnetic field" OR "PEMF"
•
Pubmed (Medline): "Scaphoid Bone" [Mesh] OR "Scaphoid" [tiab] OR "Scaphoid Fracture" [tiab] AND "Pulsed electromagnetic" [tiab] OR "Pulsed electromagnetic field" [tiab] OR "PEMF" [tiab]
•
Only articles written in English, French, or German were included
Quality of the Evidence
Level I:
Randomized controlled trials: 311–13
Level IV:
Case series: 214,15
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Pacemakers and Defibrillators
Noah E. Gordon MD, Linda L. Liu MD, in Critical Care Secrets (Fourth Edition), 2007
22 What is electromagnetic interference (EMI), and what is its relevance to pacemakers?
EMI refers to any electromagnetic radiation with the potential to affect implantable devices (pacemakers). Some hospital sources of EMI are electrocautery, diathermy, external cardioversion/defibrillators, and magnetic resonance imaging. Possible responses to interference include inappropriate inhibition or triggering of a paced output, asynchronous pacing, reprogramming, damage to device circuitry, and triggering of a defibrillator discharge. Strategies to minimize these responses involve use of bipolar leads, noise protection algorithms that filter out unwanted signals, using magnets to decrease inappropriate pacemaker triggering, and avoiding/minimizing exposure to EMI.
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Multimodality Image-Guided Lung Intervention Systems
Kongkuo Lu, ... Zhong Xue, in Cancer Theranostics, 2014
Electromagnetic Tracking
Electromagnetic (EM) spatial measurement systems determine the location of objects that are embedded with sensor coils [24,56]. When the object is placed inside the controlled, spatially varying electromagnetic fields, the signals collected from the sensor coils are transferred to the signal amplifier and processor. The phase and frequency detected from the sensor coil signals are then used to calculate the position and orientation of the sensor coil location. When embedding such sensor coils into different interventional devices such as puncture needle, ablation needle, biopsy needle, and so on, the device position and orientation can be detected. The advantage of EM tracking is that the sensor coils can be embedded onto the tip or point of interest in the device, so the device-tracking accuracy is high, and also it is convenient to track devices inside the body for safety reasons. On the other hand, customized devices have to be manufactured and approved by the U.S. Food and Drug Administration (FDA) for any procedure. Another shortcoming for EM tracking may be that the accuracy of the tracking is based on the electromagnetic field so any metal devices close to the electromagnetic field may distort it and subsequently affect the measuring accuracy.
The Aurora system (made by Northern Digital Inc. of Canada) is an example of an electromagnetic spatial measurement system; it provides small sensor coils that can be used in small needles (e.g., less than 1 mm in diameter). Various devices and needles are available for computer-assisted surgery and therapy applications such as guided needle biopsies.
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Diagnostic Bronchoscopy
Elif Küpeli MD, ... Atul C. Mehta MBBS, in Murray and Nadel's Textbook of Respiratory Medicine (Sixth Edition), 2016
Electromagnetic and Virtual Bronchoscopic Navigation
Electromagnetic navigation (EMN) and virtual bronchoscopic navigation can be used to guide the bronchoscopist to lesions that cannot be visualized in the airways, because they are either distal or paratracheal. EMN creates an electromagnetic field around the chest of a patient undergoing FB, superimposes the field upon previously acquired three-dimensional CT images, and determines the position of a locatable guide containing sensors within the endobronchial tree.196 Once steered into position, the guide is withdrawn, and biopsy tools are advanced through the guide sheath to obtain biopsy specimens at the site. In principle, the navigation system is similar to the global positioning system used in automobiles and airplanes. Virtual bronchoscopic navigation, on the other hand, creates a virtual bronchoscopic map from existing CT data and then suggests the best path to the target lesion.
EMN may improve the otherwise limited diagnostic yield of FB for peripheral lung lesions and solitary pulmonary nodules.168 Recent studies have shown that EMN increases this yield to the range of 63% to 90%.197-207 EMN and virtual bronchoscopic navigation are well tolerated and have proved to be both safe and useful in localizing small or fluoroscopically invisible lung lesions with a sufficient level of accuracy (Fig. 22-11).208,209 The ultimate value of these navigational aids and whether their benefits will justify their cost is not known.
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Therapeutics according to an Endobiogenic reflection
Kamyar M. Hedayat, Jean-Claude Lapraz, in The Theory of Endobiogeny, 2019
Energy and information therapies
Electromagnetic signaling regulates the general level of cellular, tissue, organ, and global system coherence. Each type of physiologic activity has a unique biologic window, or frequency range of pulsed electromagnetic frequencies (PEMFs).14, 15 The PEMFs ensure resonant coherence of the information presented to the cell membrane. The greater the coherence of information, the more efficient the adaptation response will be. Bioregulatory therapy with PEMFs can improve the efficiency of structural and functional activities at various levels of function.
Entrainment of neuro-cardio-pulmonary rhythms through breath work, guided meditation, positive valence emotional states, and other techniques can reduce sympathetic overdrive and help in general autonomic nervous system regulation.16–19 Certain energy-based approaches to treatment, such as acupuncture, Qi Gong and Tai Chi have been practiced as part of a larger, comprehensive prephysiologic systems approach. These therapies can be effective for a range conditions.20–27 The upstream mechanisms by which they work have not been well elucidated according to the criteria of contemporary biophysics and science.
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Potential of electromagnetic and ultrasound stimulations for bone regeneration
L. Fassina, ... S. Van Vlierberghe, in Biomaterials for Bone Regeneration, 2014
15.2.3 Cell culture inside an electromagnetic bioreactor
The electromagnetic bioreactor consisted of a carrying structure custom-machined in a polymethylmethacrylate tube. The windowed tube carried a well-plate and two solenoids whose planes were parallel (Fassina, 2006).
The gelatin scaffolds were at a distance of 5 cm from each solenoid plane. The solenoids were powered by a Biostim SPT pulse generator (Igea, Carpi, Italy) (i.e. a generator of PEMFs). Given the position of the solenoids and the characteristics of the pulse generator, the electromagnetic stimulus possessed the following parameters: intensity of the magnetic field = 2 ± 0.2 mT, amplitude of the induced electric tension = 5 ± 1 mV, signal frequency = 75 ± 2 Hz, and pulse duration = 1.3 ms. The electromagnetic bioreactor was placed into a standard cell culture incubator at 37 °C in the presence of 5% CO2. The electromagnetic culture was stimulated by the PEMF 24 h/day for a total of 22 days. The culture medium was changed on days 4, 7, 10, 13, 16, and 19.
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Volume 2
A.l.i. Bydon, ... I.a.n. Suk, in Schmidek and Sweet Operative Neurosurgical Techniques (Sixth Edition), 2012
Pulsed Electromagnetic Field Stimulation
PEMFS is based on the ability of a magnetic field to induce a secondary electric field at the location of desired fusion. The device involves current-carrying coils driven by a generator that a patient wears in a brace for 3 to 8 hours each day. Patient compliance is an important variable.229
Few studies have evaluated PEMFS. An initial study that was randomized and blinded showed that patients who wore the brace for more than 8 hours a day had higher fusion rates than those who had a brace with nonfunctional coils or those who used their brace for less than 4 hours per day.231 Other retrospective reviews have also found significantly higher fusion rates, as high as 98%.232-233 However, another study of patients who wore the PEMFS device for at least 2 hours a day did not show any improvement in fusion rates.234 Although there are limited data in support of PEMFS as an adjuvant therapy, given that it is noninvasive and there are no known side effects, its use might become more widespread after further research.
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Cellular and Molecular Mechanotransduction in Bone
Julia C. Chen, ... Christopher R. Jacobs, in Osteoporosis (Fourth Edition), 2013
Electromagnetic Fields
Electromagnetic fields regulate bone cell behavior in vivo and in vitro. For example, they alter cellular morphology, increase alkaline phosphatase activity, induce detachment and apoptosis, suppress and enhance osteoclastogenesis, induce proliferation, and regulate differentiation and mineralization depending on the parameters of stimulation. In terms of signaling, electromagnetic fields activate intracellular calcium, insulin-like growth factor (IGF), transforming growth factor β (TGF-β), PGE2, and the RANKL-OPG system. The electrosensitivity of ensembles of bone cells linked by gap junctions is greater than uncoupled cells [71]. However, critical evaluation of both in vitro and in vivo experimental evidence has suggested that, although exogenous electromagnetic fields can stimulate bone cellular activity, the endogenous fields produced by habitual loading may not elicit a significant cellular effect. This has led many investigators to consider alternative loading-induced cell-level physical signals as mediators of bone mechanobiology.
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Blood–Brain and Spinal Cord Barriers in Stress
HARI SHANKER SHARMA, in Blood-Spinal Cord and Brain Barriers in Health and Disease, 2004
XXIV. Stress Associated with Electromagnetic Radiation and Mobile Telephony
Electromagnetic fields generated from the use of mobile telephony induce stress responses in the CNS (Ono and Han, 2000; Pipkin et al., 1999; Jin et al., 2000; Morehouse and Owen, 2000; Leszcynski et al., 2002; see Hossmann and Hermann, 2003). Thus, it appears that the radiofrequency-modulated electromagnetic fields (RF-EMF) emitted by mobile phones are harmful in nature. However, the subject is still controversial (see Hossman and Hermann, 2003). Investigation of the cellular stress response following RF-EMF exposure in the range elicited by mobile phones showed altered cellular physiology, enhanced stress response, and disruption of the BBB (Cleary et al., 1997; Fritze et al., 1997b; Daniells et al., 1998; de Pomerai et al., 2000; Kwee et al., 2001; Leszcynski et al., 2002).
Stress proteins, often known as "heat shock proteins" (HSPs), regulate apoptosis (Creagh et al., 2000; Pandey et al., 2000; for details, see Chapter 17), and deregulation of apoptosis following RF-EMF-induced radiation by HSPs suggests a potential risk factor for tumor development. This is evident from the fact that HSP induction in cells following injury or insults enhances cell survival (see Westman and Sharma, 1998; for details, see Chapter 17). Thus, RF-EMF-induced induction of HSPs and prevention of apoptosis result in the survival of those cells that are supposed to die for the purpose of physiological regulation (French et al., 2001; Leszcynski et al., 2002).
Acute exposure of rats to 900-MHz/217-Hz microwaves (in the range of global system for mobile communication, GSM signal) results in the elevation of HSP72 mRNA, as well as the induction of IEGs, e.g., c-fos and c-jun mRNAs in the cerebral cortex (Fritze et al., 1997b; see Hossman and Hermann, 2003). Upregulation of HSPs 27 and p38 mitogen-activated protein kinase (P38MAPK) in cultured human endothelial cells occurs following RF-EMF radiation in the nonthermal range (Leszcynski et al., 2002). Activation of the family of small HSPs, such as HSP27 phosphorylation, inhibits apoptosis, which involves apoptosome and caspases (Pandey et al., 2000; Concannon et al., 2001, for details, see Chapter 17). Furthermore, HSP27 induces the resistance of tumor cells to death by anticancer drugs (Huot et al., 1996; Garrido et al., 1997). These observations suggest that the RF-EMF-induced expression of HSP27 not only affects tumor development, but also its drug resistance (for details, see Kyriakis and Avruch, 2001).
An increase in BBB permeability following RF-EMF exposure is seen in some animal experiments using both in vitro and in vivo studies (see Jokela et al., 1999; Hossmann and Hermann, 2003). The increased permeability of the BBB following RF-EMF exposure is mainly related to its thermal effects. However, few studies showed that BBB dysfunction can also be induced in vitro as well as in vivo by RF-EMF in the nonthermal range (Salford et al., 1994; Schirmacher et al., 2000). Fritze et al. (1997a) reported a transient induction of HSP70 response and breakdown of the BBB immediately after irradiation. A 2-h exposure of rats to RF-EMF (900 MHz, corresponding to GSM signal) at a specific absorption rate (SAR) of 2 W/kg averaged over the brain results in BBB disruption (Töre et al., 2001). However, studies using a repeated exposure of RF-EMF in the nonthermal range on BBB permeability and HSP or IEG induction are lacking. Thus, the nonthermal effects of RF-EMF on the BBB and brain dysfunction are still controversial.
The molecular mechanisms and the cellular signaling pathways involved in RF-EMF-induced BBB breakdown are not known in detail. Increased pinocytosis within endothelial cells of the cerebral cortex has been described following exposure of 2.45 GHz microwave radiation in rats (Neubauer et al., 1990). It may be that the induction of HSP27 will trigger molecular events leading to the cascade of activities causing opening of the BBB (French et al., 2001; Leszcynski et al., 2002; for details, see Chapter 17). A possibility exists that phosphorylation of HSP27 enhances actin polymerization, causing cell shrinkage and widening of the tight junctions and/or stimulation of pinocytotic activity (Lavoie et al., 1993; Piotrowicz and Levin, 1997). Thus, the effects of mobile telephony-induced RF-EMF radiation on the BBB and brain function require further investigation.
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