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1.
Rev Environ Health ; 37(2): 247-258, 2022 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-34043892

RESUMO

Millimeter wave (MM-wave) electromagnetic fields (EMFs) are predicted to not produce penetrating effects in the body. The electric but not magnetic part of MM-EMFs are almost completely absorbed within the outer 1 mm of the body. Rodents are reported to have penetrating MM-wave impacts on the brain, the myocardium, liver, kidney and bone marrow. MM-waves produce electromagnetic sensitivity-like changes in rodent, frog and skate tissues. In humans, MM-waves have penetrating effects including impacts on the brain, producing EEG changes and other neurological/neuropsychiatric changes, increases in apparent electromagnetic hypersensitivity and produce changes on ulcers and cardiac activity. This review focuses on several issues required to understand penetrating effects of MM-waves and microwaves: 1. Electronically generated EMFs are coherent, producing much higher electrical and magnetic forces then do natural incoherent EMFs. 2. The fixed relationship between electrical and magnetic fields found in EMFs in a vacuum or highly permeable medium such as air, predicted by Maxwell's equations, breaks down in other materials. Specifically, MM-wave electrical fields are almost completely absorbed in the outer 1 mm of the body due to the high dielectric constant of biological aqueous phases. However, the magnetic fields are very highly penetrating. 3. Time-varying magnetic fields have central roles in producing highly penetrating effects. The primary mechanism of EMF action is voltage-gated calcium channel (VGCC) activation with the EMFs acting via their forces on the voltage sensor, rather than by depolarization of the plasma membrane. Two distinct mechanisms, an indirect and a direct mechanism, are consistent with and predicted by the physics, to explain penetrating MM-wave VGCC activation via the voltage sensor. Time-varying coherent magnetic fields, as predicted by the Maxwell-Faraday version of Faraday's law of induction, can put forces on ions dissolved in aqueous phases deep within the body, regenerating coherent electric fields which activate the VGCC voltage sensor. In addition, time-varying magnetic fields can directly put forces on the 20 charges in the VGCC voltage sensor. There are three very important findings here which are rarely recognized in the EMF scientific literature: coherence of electronically generated EMFs; the key role of time-varying magnetic fields in generating highly penetrating effects; the key role of both modulating and pure EMF pulses in greatly increasing very short term high level time-variation of magnetic and electric fields. It is probable that genuine safety guidelines must keep nanosecond timescale-variation of coherent electric and magnetic fields below some maximum level in order to produce genuine safety. These findings have important implications with regard to 5G radiation.


Assuntos
Campos Eletromagnéticos , Micro-Ondas , Biologia , Canais de Cálcio/fisiologia , Canais de Cálcio/efeitos da radiação , Campos Eletromagnéticos/efeitos adversos , Micro-Ondas/efeitos adversos , Física
2.
Radiat Res ; 195(1): 101-113, 2021 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-33206197

RESUMO

The recent rollout of 5G telecommunications systems has spawned a renewed call to re-examine the possibility of so-called "non-thermal" harmful effects of radiofrequency (RF) radiation. The possibility of calcium being affected by low-level RF has been the subject of research for nearly 50 years and there have been recent suggestions that voltage-gated calcium channels (VGCCs) are "extraordinarily sensitive" to ambient RF fields. This article examines the feasibility of particularly modulated RF coupling to gating mechanisms in VGCCs and also reviews studies from the literature from the last 50 years for consistency of outcome. We conclude that the currents induced by fields at the ICNIRP guideline limits are many orders of magnitude below those needed to affect gating, and there would need to be a biological mechanism for detection and rectification of the extremely-low-frequency (ELF) modulations, which has not been demonstrated. Overall, experimental studies have not validated that RF affects Ca2+ transport into or out of cells.


Assuntos
Cálcio/metabolismo , Campos Eletromagnéticos/efeitos adversos , Ondas de Rádio/efeitos adversos , Canais de Cálcio/genética , Canais de Cálcio/efeitos da radiação , Humanos
3.
Neuron ; 103(1): 66-79.e12, 2019 07 03.
Artigo em Inglês | MEDLINE | ID: mdl-31104951

RESUMO

The precision and reliability of synaptic information transfer depend on the molecular organization of voltage-gated calcium channels (VGCCs) within the presynaptic membrane. Alternative splicing of exon 47 affects the C-terminal structure of VGCCs and their affinity to intracellular partners and synaptic vesicles (SVs). We show that hippocampal synapses expressing VGCCs either with exon 47 (CaV2.1+47) or without (CaV2.1Δ47) differ in release probability and short-term plasticity. Tracking single channels revealed transient visits (∼100 ms) of presynaptic VGCCs in nanodomains (∼80 nm) that were controlled by neuronal network activity. Surprisingly, despite harboring prominent binding sites to scaffold proteins, CaV2.1+47 persistently displayed higher mobility within nanodomains. Synaptic accumulation of CaV2.1 was accomplished by optogenetic clustering, but only CaV2.1+47 increased transmitter release and enhanced synaptic short-term depression. We propose that exon 47-related alternative splicing of CaV2.1 channels controls synapse-specific release properties at the level of channel mobility-dependent coupling between VGCCs and SVs.


Assuntos
Canais de Cálcio/genética , Plasticidade Neuronal/genética , Plasticidade Neuronal/fisiologia , Sinapses/fisiologia , Sequência de Aminoácidos , Animais , Sítios de Ligação , Canais de Cálcio/efeitos da radiação , Potenciais Pós-Sinápticos Excitadores/fisiologia , Feminino , Células HEK293 , Humanos , Luz , Neurotransmissores/metabolismo , Optogenética , Gravidez , Isoformas de Proteínas/genética , Ratos , Vesículas Sinápticas/fisiologia
4.
Environ Res ; 164: 405-416, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29573716

RESUMO

Repeated Wi-Fi studies show that Wi-Fi causes oxidative stress, sperm/testicular damage, neuropsychiatric effects including EEG changes, apoptosis, cellular DNA damage, endocrine changes, and calcium overload. Each of these effects are also caused by exposures to other microwave frequency EMFs, with each such effect being documented in from 10 to 16 reviews. Therefore, each of these seven EMF effects are established effects of Wi-Fi and of other microwave frequency EMFs. Each of these seven is also produced by downstream effects of the main action of such EMFs, voltage-gated calcium channel (VGCC) activation. While VGCC activation via EMF interaction with the VGCC voltage sensor seems to be the predominant mechanism of action of EMFs, other mechanisms appear to have minor roles. Minor roles include activation of other voltage-gated ion channels, calcium cyclotron resonance and the geomagnetic magnetoreception mechanism. Five properties of non-thermal EMF effects are discussed. These are that pulsed EMFs are, in most cases, more active than are non-pulsed EMFs; artificial EMFs are polarized and such polarized EMFs are much more active than non-polarized EMFs; dose-response curves are non-linear and non-monotone; EMF effects are often cumulative; and EMFs may impact young people more than adults. These general findings and data presented earlier on Wi-Fi effects were used to assess the Foster and Moulder (F&M) review of Wi-Fi. The F&M study claimed that there were seven important studies of Wi-Fi that each showed no effect. However, none of these were Wi-Fi studies, with each differing from genuine Wi-Fi in three distinct ways. F&M could, at most conclude that there was no statistically significant evidence of an effect. The tiny numbers studied in each of these seven F&M-linked studies show that each of them lack power to make any substantive conclusions. In conclusion, there are seven repeatedly found Wi-Fi effects which have also been shown to be caused by other similar EMF exposures. Each of the seven should be considered, therefore, as established effects of Wi-Fi.


Assuntos
Canais de Cálcio , Campos Eletromagnéticos , Adolescente , Adulto , Apoptose , Canais de Cálcio/efeitos da radiação , Campos Eletromagnéticos/efeitos adversos , Humanos , Micro-Ondas/efeitos adversos , Estresse Oxidativo
5.
Cardiovasc Res ; 113(3): 354-366, 2017 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-28395022

RESUMO

Aims: Anatomical re-entry is an important mechanism of ventricular tachycardia, characterized by circular electrical propagation in a fixed pathway. It's current investigative and therapeutic approaches are non-biological, rather unspecific (drugs), traumatizing (electrical shocks), or irreversible (ablation). Optogenetics is a new biological technique that allows reversible modulation of electrical function with unmatched spatiotemporal precision using light-gated ion channels. We therefore investigated optogenetic manipulation of anatomical re-entry in ventricular cardiac tissue. Methods and results: Transverse, 150-µm-thick ventricular slices, obtained from neonatal rat hearts, were genetically modified with lentiviral vectors encoding Ca2+-translocating channelrhodopsin (CatCh), a light-gated depolarizing ion channel, or enhanced yellow fluorescent protein (eYFP) as control. Stable anatomical re-entry was induced in both experimental groups. Activation of CatCh was precisely controlled by 470-nm patterned illumination, while the effects on anatomical re-entry were studied by optical voltage mapping. Regional illumination in the pathway of anatomical re-entry resulted in termination of arrhythmic activity only in CatCh-expressing slices by establishing a local and reversible, depolarization-induced conduction block in the illuminated area. Systematic adjustment of the size of the light-exposed area in the re-entrant pathway revealed that re-entry could be terminated by either wave collision or extinction, depending on the depth (transmurality) of illumination. In silico studies implicated source-sink mismatches at the site of subtransmural conduction block as an important factor in re-entry termination. Conclusions: Anatomical re-entry in ventricular tissue can be manipulated by optogenetic induction of a local and reversible conduction block in the re-entrant pathway, allowing effective re-entry termination. These results provide distinctively new mechanistic insight into re-entry termination and a novel perspective for cardiac arrhythmia management.


Assuntos
Arritmias Cardíacas/prevenção & controle , Canais de Cálcio/efeitos da radiação , Luz , Miócitos Cardíacos/efeitos da radiação , Optogenética , Rodopsina/efeitos da radiação , Potenciais de Ação , Animais , Animais Recém-Nascidos , Arritmias Cardíacas/genética , Arritmias Cardíacas/metabolismo , Arritmias Cardíacas/fisiopatologia , Proteínas de Bactérias/biossíntese , Proteínas de Bactérias/genética , Canais de Cálcio/biossíntese , Canais de Cálcio/genética , Simulação por Computador , Vetores Genéticos , Lentivirus/genética , Proteínas Luminescentes/biossíntese , Proteínas Luminescentes/genética , Modelos Cardiovasculares , Miócitos Cardíacos/metabolismo , Ratos Wistar , Rodopsina/biossíntese , Rodopsina/genética , Fatores de Tempo , Técnicas de Cultura de Tecidos , Transfecção , Imagens com Corantes Sensíveis à Voltagem
6.
Brain Res ; 1646: 560-569, 2016 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-27346366

RESUMO

A three-dimensional Brownian Dynamics (BD) in combination with electrostatic calculations is employed to specifically study the effects of radiation of high frequency electromagnetic fields on the conduction and concentration profile of calcium ions inside the voltage-gated calcium channels. The electrostatic calculations are performed using COMSOL Multiphysics by considering dielectric interfaces effectively. The simulations are performed for different frequencies and intensities. The simulation results show the variations of conductance, average number of ions and the concentration profiles of ions inside the channels in response to high frequency radiation. The ionic current inside the channel increases in response to high frequency electromagnetic field radiation, and the concentration profiles show that the residency of ions in the channel decreases accordingly.


Assuntos
Canais de Cálcio/metabolismo , Canais de Cálcio/efeitos da radiação , Sinalização do Cálcio/efeitos da radiação , Cálcio/metabolismo , Cálcio/efeitos da radiação , Campos Eletromagnéticos , Simulação de Dinâmica Molecular , Fenômenos Biofísicos , Modelos Teóricos
7.
J Chem Neuroanat ; 75(Pt B): 43-51, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-26300312

RESUMO

Non-thermal microwave/lower frequency electromagnetic fields (EMFs) act via voltage-gated calcium channel (VGCC) activation. Calcium channel blockers block EMF effects and several types of additional evidence confirm this mechanism. Low intensity microwave EMFs have been proposed to produce neuropsychiatric effects, sometimes called microwave syndrome, and the focus of this review is whether these are indeed well documented and consistent with the known mechanism(s) of action of such EMFs. VGCCs occur in very high densities throughout the nervous system and have near universal roles in release of neurotransmitters and neuroendocrine hormones. Soviet and Western literature shows that much of the impact of non-thermal microwave exposures in experimental animals occurs in the brain and peripheral nervous system, such that nervous system histology and function show diverse and substantial changes. These may be generated through roles of VGCC activation, producing excessive neurotransmitter/neuroendocrine release as well as oxidative/nitrosative stress and other responses. Excessive VGCC activity has been shown from genetic polymorphism studies to have roles in producing neuropsychiatric changes in humans. Two U.S. government reports from the 1970s to 1980s provide evidence for many neuropsychiatric effects of non-thermal microwave EMFs, based on occupational exposure studies. 18 more recent epidemiological studies, provide substantial evidence that microwave EMFs from cell/mobile phone base stations, excessive cell/mobile phone usage and from wireless smart meters can each produce similar patterns of neuropsychiatric effects, with several of these studies showing clear dose-response relationships. Lesser evidence from 6 additional studies suggests that short wave, radio station, occupational and digital TV antenna exposures may produce similar neuropsychiatric effects. Among the more commonly reported changes are sleep disturbance/insomnia, headache, depression/depressive symptoms, fatigue/tiredness, dysesthesia, concentration/attention dysfunction, memory changes, dizziness, irritability, loss of appetite/body weight, restlessness/anxiety, nausea, skin burning/tingling/dermographism and EEG changes. In summary, then, the mechanism of action of microwave EMFs, the role of the VGCCs in the brain, the impact of non-thermal EMFs on the brain, extensive epidemiological studies performed over the past 50 years, and five criteria testing for causality, all collectively show that various non-thermal microwave EMF exposures produce diverse neuropsychiatric effects.


Assuntos
Depressão/etiologia , Depressão/psicologia , Campos Eletromagnéticos/efeitos adversos , Micro-Ondas/efeitos adversos , Animais , Canais de Cálcio/fisiologia , Canais de Cálcio/efeitos da radiação , Telefone Celular/tendências , Depressão/epidemiologia , Humanos , Memória/fisiologia , Memória/efeitos da radiação , Exposição Ocupacional/efeitos adversos , Polimorfismo Genético/fisiologia , Polimorfismo Genético/efeitos da radiação
8.
Proc Natl Acad Sci U S A ; 110(6): 2383-8, 2013 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-23345429

RESUMO

Human skin is constantly exposed to solar ultraviolet radiation (UVR), the most prevalent environmental carcinogen. Humans have the unique ability among mammals to respond to UVR by increasing their skin pigmentation, a protective process driven by melanin synthesis in epidermal melanocytes. The molecular mechanisms used by melanocytes to detect and respond to long-wavelength UVR (UVA) are not well understood. We recently identified a UVA phototransduction pathway in melanocytes that is mediated by G protein-coupled receptors and leads to rapid calcium mobilization. Here we report that in human epidermal melanocytes physiological doses of UVR activate a retinal-dependent current mediated by transient receptor potential A1 (TRPA1) ion channels. The TRPA1 photocurrent is UVA-specific and requires G protein and phospholipase C signaling, thus contributing to UVA-induced calcium responses to mediate downstream cellular effects and providing evidence for TRPA1 function in mammalian phototransduction. Remarkably, TRPA1 activation is required for the UVR-induced and retinal-dependent early increase in cellular melanin. Our results show that TRPA1 is essential for a unique extraocular phototransduction pathway in human melanocytes that is activated by physiological doses of UVR and results in early melanin synthesis.


Assuntos
Canais de Cálcio/metabolismo , Canais de Cálcio/efeitos da radiação , Transdução de Sinal Luminoso/fisiologia , Transdução de Sinal Luminoso/efeitos da radiação , Melanócitos/metabolismo , Melanócitos/efeitos da radiação , Proteínas do Tecido Nervoso/metabolismo , Proteínas do Tecido Nervoso/efeitos da radiação , Canais de Potencial de Receptor Transitório/metabolismo , Canais de Potencial de Receptor Transitório/efeitos da radiação , Animais , Células CHO , Canais de Cálcio/genética , Sinalização do Cálcio/efeitos da radiação , Células Cultivadas , Cricetinae , Cricetulus , Proteínas de Ligação ao GTP/metabolismo , Humanos , Melaninas/biossíntese , Modelos Biológicos , Proteínas do Tecido Nervoso/genética , Técnicas de Patch-Clamp , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/efeitos da radiação , Transdução de Sinais/efeitos da radiação , Canal de Cátion TRPA1 , Canais de Potencial de Receptor Transitório/genética , Raios Ultravioleta
9.
J Membr Biol ; 240(2): 63-71, 2011 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21249346

RESUMO

We examined the effects of 50-Hz magnetic fields in the range of flux densities relevant to our current environmental exposures on action potential (AP), after-hyperpolarization potential (AHP) and neuronal excitability in neurons of land snails, Helix aspersa. It was shown that when the neurons were exposed to magnetic field at the various flux densities, marked changes in neuronal excitability, AP firing frequency and AHP amplitude were seen. These effects seemed to be related to the intensity, type (single and continuous or repeated and cumulative) and length of exposure (18 or 20 min). The extremely low-frequency (ELF) magnetic field exposures affect the excitability of F1 neuronal cells in a nonmonotonic manner, disrupting their normal characteristic and synchronized firing patterns by interfering with the cell membrane electrophysiological properties. Our results could explain one of the mechanisms and sites of action of ELF magnetic fields. A possible explanation of the inhibitory effects of magnetic fields could be a decrease in Ca(2+) influx through inhibition of voltage-gated Ca(2+) channels. The detailed mechanism of effect, however, needs to be further studied under voltage-clamp conditions.


Assuntos
Canais de Cálcio/fisiologia , Campos Eletromagnéticos/efeitos adversos , Caracois Helix/fisiologia , Neurônios/fisiologia , Potenciais de Ação/fisiologia , Potenciais de Ação/efeitos da radiação , Animais , Canais de Cálcio/efeitos da radiação , Meio Ambiente , Caracois Helix/efeitos da radiação , Neurônios/efeitos da radiação , Técnicas de Patch-Clamp , Transdução de Sinais/efeitos da radiação
10.
Exp Neurol ; 226(1): 173-82, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-20816824

RESUMO

Throughout life, new neurons are continuously generated in the hippocampus, which is therefore a major site of structural plasticity in the adult brain. We recently demonstrated that extremely low-frequency electromagnetic fields (ELFEFs) promote the neuronal differentiation of neural stem cells in vitro by up-regulating Ca(v)1-channel activity. The aim of the present study was to determine whether 50-Hz/1 mT ELFEF stimulation also affects adult hippocampal neurogenesis in vivo, and if so, to identify the molecular mechanisms underlying this action and its functional impact on synaptic plasticity. ELFEF exposure (1 to 7 h/day for 7 days) significantly enhanced neurogenesis in the dentate gyrus (DG) of adult mice, as documented by increased numbers of cells double-labeled for 5-bromo-deoxyuridine (BrdU) and doublecortin. Quantitative RT-PCR analysis of hippocampal extracts revealed significant ELFEF exposure-induced increases in the transcription of pro-neuronal genes (Mash1, NeuroD2, Hes1) and genes encoding Ca(v)1.2 channel α(1C) subunits. Increased expression of NeuroD1, NeuroD2 and Ca(v)1 channels was also documented by Western blot analysis. Immunofluorescence experiments showed that, 30 days after ELFEF stimulation, roughly half of the newly generated immature neurons had survived and become mature dentate granule cells (as shown by their immunoreactivity for both BrdU and NeuN) and were integrated into the granule cell layer of the DG. Electrophysiological experiments demonstrated that the new mature neurons influenced hippocampal synaptic plasticity, as reflected by increased long-term potentiation. Our findings show that ELFEF exposure can be an effective tool for increasing in vivo neurogenesis, and they could lead to the development of novel therapeutic approaches in regenerative medicine.


Assuntos
Hipocampo/efeitos da radiação , Neurogênese/efeitos da radiação , Animais , Antimetabólitos , Western Blotting , Bromodesoxiuridina , Canais de Cálcio/efeitos da radiação , Canais de Cálcio Tipo L/metabolismo , Canais de Cálcio Tipo L/efeitos da radiação , Diferenciação Celular/efeitos da radiação , Campos Eletromagnéticos , Imunofluorescência , Hipocampo/citologia , Potenciação de Longa Duração , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Rede Nervosa/fisiologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa
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