外加磁场作用下磁性Fe3O4纳米粒子对肝癌细胞增殖和凋亡的影响

目的：观察磁性四氧化三铁（Fe3O4）纳米粒子对肝癌细胞的体外作用,并研究外加稳恒磁场（SMF）或交变磁场（EMF）对FeID4纳米粒子作用的影响。方法：光镜下观察CBRH-7919细胞对Fe3O4纳米粒子的吞噬作用;MTT法检测Fe304纳米粒子对大鼠肝癌细胞株CBRH-7919的毒性及外加磁场的影响;流式细胞术检测外加磁场作用下Fe3O4纳米粒子对细胞凋亡及线粒体膜电位的影响。结果：光镜下可见CBRH-7919细胞吞噬大量Fe3O4纳米粒子入胞浆,且交变磁场作用下细胞的吞噬量增加。30-100μg／mLFe3O4纳米粒子作用于CBRH-7919细胞未产生细胞毒性,稳恒磁场对其作用无影响,而交变磁场能增加Fe3O4纳米粒子的毒性,使细胞活性降低、凋亡率增加、线粒体膜电位降低。结论：交变磁场能增加CBRH-7919细胞对Fe3O4纳米粒子的吞噬并产生细胞毒性。     

On the modulation effect of pulsing and static magnetic fields and mechanical vibrations on barley seed hydration

The changes of wet and dry weights of barley seed in different periods of swelling were studied in seeds treated with Extremely Low Frequency Electromagnetic Fields (ELF EMF), Static Magnetic Fields (SMF) and Mechanical Vibrations (MV) in cold (4 degrees C) and warm (20 degrees C) distilled water as well as in seeds non-treated (control). The metabolic dependent seed hydration, dry weight loss and water binding in seed were modulated by preliminary EMF, SMF and MV-induced treatment of distilled water. The specific electrical conductivity (SEC) of control and treated distilled water was measured before the seed incubation. Frequency and intensity "windows" (i.e. range of frequency or intensity) for the effect of EMF, MV and SMF (correspondingly) on seed hydration, solubility and water binding in seed were studied. These "windows" were different in various phases of seed swelling. It is suggested that water structure modification is the result of valence angle changes (SMF and EMF) and dipole molecules vibration (EMF and MV) has different effects on the process of hydration, solubility and water binding in seed. These results are important from the point of understanding the mechanisms of the biological effect of EMF, as well as from the point of agriculture.     

Increase of seed germination,growth and membrane integrity of wheat seedlings by exposure to static and a 10-KHz electromagnetic field

There is a large body of experimental data demonstrating various effects of magnetic field (MF) on plants growth and development. Although the mechanism(s) of perception of MF by plants is not yet elucidated, there is a possibility that like other stimuli, MF exerts its effects on plants by changing membrane integrity and conductance of its water channels, thereby influencing growth characteristics. In this study, the seeds of wheat (Triticum aestivum L. cv. Kavir) were imbibed in water overnight and then treated with or without a 30-mT static magnetic field (SMF) and a 10-kHz electromagnetic field (EMF) for 4 days, each 5 h. Water uptake of seeds reduced 5 h of the treatment with EMF but did not show changes in SMF treatment. Exposure to both magnetic fields did not affect germination percent of the seeds but increased the speed of germination, compared to the control group. Treatment with EMF significantly reduced seedling length and subsequently vigor index I, while SMF had no effects on these parameters. Both treatments significantly increased vigor index II, compared to the control group. These treatments also remarkably increased catalase activity and proline contents of seedlings but reduced the activity of peroxidase, the rate of lipid peroxidation and electrolyte leakages of membranes. The results suggest promotional effects of EMFs on membrane integrity and growth characteristics of wheat seedlings.     

The effect of magnetic fields on the growth and division of the lon mutant of Escherichia coli K-12

It was shown that the static magnetic field (SMF) and electromagnetic field (EMF) caused inhibition of the cell division in Escherichia coli K-12 lon mutant. The low-frequency EMF 4 Hz led to the 20% survival, but EMF at 50 Hz increased the survival of cells up to 53%. After exposure to magnetic field cells lost capacity for division and grow as filaments, unable to form the colonies on the solid media.     

Electromagnetic fields instantaneously modulate nitric oxide signaling in challenged biological systems

This study shows that a non-thermal pulse-modulated RF signal (PRF), configured to modulate calmodulin (CaM) activation via acceleration of Ca²⁺ binding kinetics, produced an immediate nearly 3-fold increase in nitric oxide (NO) from dopaminergic MN9D cultures (P < 0.001). NO was measured electrochemically in real-time using a NO selective membrane electrode, which showed the PRF effect occurred within the first seconds after lipopolysaccharide (LPS) challenge. Further support that the site of action of PRF involves CaM is provided in human fibroblast cultures challenged with low serum and exposed for 15 min to the identical PRF signal. In this case a CaM antagonist W-7 could be added to the culture 3 h prior to PRF exposure. Those results showed the PRF signal produced nearly a two-fold increase in NO, which could be blocked by W-7 (P < 0.001). To the authors’ knowledge this is the first report of a real-time effect of non-thermal electromagnetic fields (EMF) on NO release from challenged cells. The results provide mechanistic support for the many reported bioeffects of EMF in which NO plays a role. Thus, in a typical clinical application for acute post operative pain, or chronic pain from, e.g., osteoarthritis, EMF therapy could be employed to modulate the dynamics of NO via Ca/CaM-dependent constitutive nitric oxide synthase (cNOS) in the target tissue. This, in turn, would modulate the dynamics of the signaling pathways the body uses in response to the various phases of healing after physical or chemical insult or injury.     

Complete deoxygenation from a hemoglobin solution by an electrochemical method and heat treatment for virus inactivation

Hemoglobin (Hb) has been widely studied as a raw material for various types of oxygen carriers. In the purification of Hb from red blood cells including virus inactivation and denaturation of other proteins and the long-term storage of Hb vesicles (HbV), a deoxygenation process is one of the important processes because of the high stability of deoxygenated Hb to heating and metHb formation. Though an oxygenated Hb solution can be deoxygenated with an artificial lung, it is difficult to reduce the oxygen partial pressure of the Hb solution to less than 10 Torr. We developed an electrochemical system for complete deoxygenation of the Hb solution at the cathode compartment using hydrogen containing nitrogen gas at the anode compartment. Oxygen in the Hb solution was reduced to OH(-) at the cathode compartment within several minutes at a potential value of -1.67 V and was finally converted to water by neutralization with H(+) from the anode in the whole system. The resulting completely deoxygenated Hb could tolerate heat treatment at 62 degrees C for 10 h with no denaturation of deoxygenated Hb. The metHb formation rate of reoxygenated Hb at 37 degrees C was not changed after heat treatment. Furthermore, vesicular stomatitis virus (VSV) could be inactivated at an inactivation degree of more than 5.96 log by heat treatment.     

Generating controlled reducing environments in aerobic recombinant Escherichia coli fermentations: effects on cell growth, oxygen uptake, heat shock protein expression, and in vivo CAT activity

The independent control of culture redox potential (CRP) by the regulated addition of a reducing agent, dithiothreitol (DTT) was demonstrated in aerated recombinant Escherichia coli fermentations. Moderate levels of DTT addition resulted in minimal changes to specific oxygen uptake, growth rate, and dissolved oxygen. Excessive levels of DTT addition were toxic to the cells resulting in cessation of growth. Chloramphenicol acetyltransferase (CAT) activity (nmoles/microgram total protein min.) decreased in batch fermentation experiments with respect to increasing levels of DTT addition. To further investigate the mechanisms affecting CAT activity, experiments were performed to assay heat shock protein expression and specific CAT activity (nmoles/microgram CAT min.). Expression of such molecular chaperones as GroEL and DnaK were found to increase after addition of DTT. Additionally, sigma factor 32 (sigma32) and several proteases were seen to increase dramatically during addition of DTT. Specific CAT activity (nmoles/microgram CAT min. ) varied greatly as DTT was added, however, a minimum in activity was found at the highest level of DTT addition in E. coli strains RR1 [pBR329] and JM105 [pROEX-CAT]. In conjunction, cellular stress was found to reach a maximum at the same levels of DTT. Although DTT addition has the potential for directly affecting intracellular protein folding, the effects felt from the increased stress within the cell are likely the dominant effector. That the effects of DTT were measured within the cytoplasm of the cell suggests that the periplasmic redox potential was also altered. The changes in specific CAT activity, molecular chaperones, and other heat shock proteins, in the presence of minimal growth rate and oxygen uptake alterations, suggest that the ex vivo control of redox potential provides a new process for affecting the yield and conformation of heterologous proteins in aerated E. coli fermentations.     

Use of dual wavelength spectrophotometry and continuous enzymatic depletion of oxygen for determination of the oxygen binding constants of hemoglobin

A small stopped-flow cuvette was built into a computer-controlled Cary 210 spectrophotometer. The enzymatic depletion of oxygen in solutions of hemoglobin and myoglobin was initiated by flowing the hemeproteins with the enzyme against a solution of the hemeproteins containing the appropriate substrate. The deoxygenation was homogeneous throughout the solution. Oxygen activity was calculated at each instant of time from the fractional saturation of Mb, determined from observations at the Hb/HbO2 isosbestic wavelength. Fractional saturation of Hb was determined from absorbances at the Mb/MbO2 isosbestic wavelength. The spectrophotometer cycled between these two wavelengths during the deoxygenation. The deoxygenation of HbO2 was largely complete in 20-25 min, whereas the deoxygenation of MbO2 was allowed to proceed for about 1 h. This procedure eliminates equilibration of Hb solutions with a gas phase and replaces oxygen electrode readings with spectrophotometric sensing by Mb, providing essentially instantaneous determinations of oxygen activity and hence 250-500 or more independent data points per run. The Mb and Hb data vectors require several manipulations to correct for small relative displacements in time and for small non-isosbestic effects. Detailed consideration of the enzyme kinetics allowed oxygen activities to be determined in regions where Mb is a poor sensor. Studies of HbO2 deoxygenation as a function of wavelength show that the determination of the four Adair constants requires in addition the determination of three spectroscopic parameters. Values of the apparent Adair constants, determined without these spectroscopic parameters, depend strongly on the monitoring wavelength.     

Exposure to an inhomogeneous static magnetic field increases thermal pain threshold in healthy human volunteers

In the present experiment, the effect of a single 30 min inhomogeneous static magnetic field (SMF) exposure on thermal pain threshold (TPT) was examined in 15 young healthy human volunteers. The SMF had a maximum peak‐to‐peak amplitude of 330 mT with a maximum gradient of 13.2 T/m. In either of two experimental sessions (SMF or SHAM), four blocks of 12 TPT trials were carried out under SMF or SHAM exposure on all fingertips of the dominant hand, excluding the thumb. TPT and visual analog scale (VAS) data were recorded at 0, 15, and 30 min exposure time, and 30 min following exposure. SMF treatment resulted in a statistically significant increase in TPT during the entire exposure duration and diminished within‐block thermal habituation, leaving pain perception unchanged. These results indicate that SMF‐induced peripheral neuronal or circulatory mechanisms may be involved in the observed TPT increase by setting the pain fibre adaptation potential to higher levels. Bioelectromagnetics 32:131–139, 2011. © 2010 Wiley‐Liss, Inc.     

Project NEMESIS: perception of a 50 Hz electric and magnetic field at low intensities (laboratory experiment).

The Electrical Hypersensitivity Syndrome (EHS) is a condition where people suffer from various nonspecific health symptoms attributed to an assumed adverse effect of electric and magnetic fields (EMF). Many EHS patients report the ability to consciously perceive EMF at very low intensities. The existence of a direct EMF perception could be the key to explain at least partially the aetiology of EHS through stress mechanisms and allow the comparison with well known environmental stressors such as noise or odor. The double blind laboratory experiment tested the hypothesis that there are subjects with the ability to perceive 50 Hz EMF at 100 V/m and 6 microT (EMF sensitive) and to investigate the prevalence of EMF sensitivity in a group consisting of subjects with or without self-reported EHS. A total of 63 volunteers, 49 with EHS and 14 controls, took part in the EMF perception experiment, where 10 sham and 10 exposed 2 min blocks had to be judged in randomized sequence (field on/field off). Seven out of 63 subjects reached a statistically significant result which points to the existence of a small EMF sensitive subgroup within the study group. There was no relevant difference between the subjects with self reported EHS and those without in terms of the success rate in the field perception experiment, as well as the number and types of symptoms encountered during the test. The results of the EMF perception experiment suggest that EHS is not a prerequisite for the ability to consciously perceive weak EMF and vice versa.     

Investigation on the effect of static magnetic field up to 30 mT on viability percent,proliferation rate and IC50 of HeLa and fibroblast cells

Abstract

We have investigated the effects of static magnetic field (SMF) on the viability of the human cervical cancer (HeLa) cell line and fibroblast cells. The cells were cultured in DMEM medium and treated several times (24, 48,72 and 96?h) and at several intensities (5, 10, 20 and 30?mT) of magnetic field (MF). The cytotoxicity and cell viability percent in treated cells were performed using MTT assay by evaluating mitochondrial dehydrogenase activity. The MF ability on inducing cell death or inhibiting biochemical function was reported as cell death percent. The results showed that the increase of MF intensity and the time that cells were exposed to this treatment increased sharply cell death percent and proliferation rate in HeLa cell compare to fibroblast cells. Our data suggest that SMF biological effects on cell death were different in our selected targets. Cell type and time of exposure have been therefore found to be significant factors. These findings could be used to improve new effective method using SMF in conjunction with the common therapeutic approaches.     

Myosin Light Chain Modification Depending on Magnetic Fields: II. Experimental

Recent experiments have revealed that Ca²⁺ -calmodulin dependent myosin light chain phosphorylation in a cell-free preparation exhibits unexpectedly high sensitivity to weak magnetic fields. This enzyme system is a well-studied biochemical system, which appears to depend upon ion binding. A previous article in this journal discussed the theoretical background of myosin phosphorylation and the ion-dependent interactions of EMF with soft tissues. Because of the electromagnetic field (EMF) sensitivity of this cell-free system, experiments were designed to test the effect of a pulsed radio frequency (PRF) field, pulsating magnetic fields (TEMF), gradient magnetic fields (Magnabloc), and homogeneous static magnetic fields (in Helmholtz arrangement) designed for clinical application. It is concluded that these various magnetic fields affect this cell-free enzyme system by modulating ion–protein interactions.     

Combined effect of X‐ray radiation and static magnetic fields on reactive oxygen species in rat lymphocytes in vitro

The aim of this study was to investigate the effect of static magnetic fields (SMF) on reactive oxygen species induced by X‐ray radiation. The experiments were performed on lymphocytes from male albino Wistar rats. After exposure to 3 Gy X‐ray radiation (with a dose rate of 560 mGy/min) the measurement of intracellular reactive oxygen species in lymphocytes, using a fluorescent probe, was done before exposure to the SMF, and after 15 min, 1 and 2 h of exposure to the SMF or a corresponding incubation time. For SMF exposure, 0 mT (50 µT magnetic field induction opposite to the geomagnetic field) and 5 mT fields were chosen. The trend of SMF effects for 0 mT was always opposite that of 5 mT. The first one decreased the rate of fluorescence change, while the latter one increased it. Bioelectromagnetics 34:333–336, 2013. © 2012 Wiley Periodicals, Inc.     

The response of human bacteria to static magnetic field and radiofrequency electromagnetic field

Cell phones and electronic appliances and devices are inseparable from most people in modern society and the electromagnetic field (EMF) from the devices is a potential health threat. Although the direct health effect of a cell phone and its radiofrequency (RF) EMF to human is still elusive, the effect to unicellular organisms is rather apparent. Human microbiota, including skin microbiota, has been linked to a very significant role in the health of a host human body. It is important to understand the response of human skin microbiota to the RF-EMF from cell phones and personal electronic devices, since this may be one of the potential mechanisms of a human health threat brought about by the disruption of the intimate and balanced host-microbiota relationship. Here, we investigated the response of both laboratory culture strains and isolates of skin bacteria under static magnetic field (SMF) and RF-EMF. The growth patterns of laboratory cultures of Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus epidermidis under SMF were variable per different species. The bacterial isolates of skin microbiota from 4 subjects with different cell phone usage history also showed inconsistent growth responses. These findings led us to hypothesize that cell phone level RF-EMF disrupts human skin microbiota. Thus, the results from the current study lay ground for more comprehensive research on the effect of RF-EMF on human health through the human-microbiota relationship.     

Rapid preparation of native alpha and beta chains of human hemoglobin.

1. Current procedures for the isolation of native chains of hemoglobin employ two ion exchange columns for each chain and result in readily autoxidizable chains with measurable contamination by Hb and Hg. 2. In the new procedure, altered buffer conditions on the first column reduce Hb contamination from 2 to 5% to less than 1%, the limit of detectability. 3. The second column and lengthy washes with beta mercaptoethanol are replaced by incubation with DTT for 1 min for alpha chains and, for beta chains, three incubations with DTT and separations by gel-filtration. The residual Hg is less than 0.1%. 4. Oxidations in the previous procedure resulted in low yields and unreliable spectroscopic assessments of bound Hg. The new procedure resulted in a simple UV assay for Hg-free chains. 5. Hemoglobin reconstituted from these oxy-chains was identical to native Hb in oxygen binding equilibria and in the kinetics of CO binding following laser photolysis.     

Dithiothreitol enhances Listeria monocytogenes mediated cell cytotoxicity

The hybridoma Ped-2E9 based cytotoxicity assay was developed to distinguish virulent from avirulent Listeria species in 6 hr. The cytotoxicity effect on Ped-2E9 was reported to be primarily due the cytolytic action of listeriolysin O (LLO), produced by L. monocytogenes. In this study, the effect of a reducing agent, dithiothreitol (DTT, 0-2 mM) that is known to activate LLO was investigated to make the Ped-2E9 based cytotoxicity assay an even more sensitive and rapid. Also, we examined the effect of fetal bovine serum (FBS, 0-50%), a common ingredient of tissue culture media on cytotoxicity. A DTT concentration of 0.5 mM gave an optimum cytotoxicity effect, which could be measured by both alkaline phosphatase (AP) and lactate dehydrogenase (LDH) assays in just 1.5-2 hr. FBS, at levels between 10 to 50%, significantly inhibited Listeria-mediated cytotoxicity. Concentrated culture filtrates from L. monocytogenes or LLO producing recombinant L. innocua (prfA+ hlyA+) strain also caused cytotoxicity effects, which were observed by scanning electron microscopy or a cytotoxicity assay in 2-3 hr. Interestingly, addition of DTT to culture filtrates produced 100% cell cytotoxicity in just 15 min. This indicated that LLO activity, which is responsible for Ped-2E9 cytotoxicity, was augmented several folds with the addition of a reducing agent. Examination of Listeria isolates belonging to different serogroups from clinical sources or naturally contaminated meat products with DTT gave cytotoxicity results in 2 hr, which were comparable to the 5-hr assay analyzed concurrently without DTT. These results indicated that DTT, which activated the LLO, could be used in the cytotoxicity assay to enhance Listeria-mediated Ped-2E9 cell cytotoxicity. This knowledge will greatly assist us to develop a user-friendly rapid assay to screen cytopathogenic properties of Listeria species.     

Static magnetic field influence on rat brain function detected by heart rate monitoring

The aim of the present study was to identify the effects of a static magnetic field (SMF) on rat brain structures that control autonomic functions, specifically heart rate and heart rhythmicity. The experiments were carried out on 44 male Wistar rats under ketamine-xylazine anesthesia. SMF was induced using samarium-cobalt fused magnets (20 x 20 x 10 mm in size) placed bitemporally. Magnetic induction intensity was 100 mT on the surface of the head. Duration of magnetic field application was 15 min. An electrocardiogram was recorded from limb lead II, and both heart rate (average duration of cardiac cycles) and heart rhythmicity were analyzed before and after SMF application. SMF evoked changes in both heart rate and rhythm in 80% of the animals; the predominant effects were bradycardia and disappearance of respiratory sinus arrhythmia. However, the effectiveness of SMF in large measure depends on both functional peculiarities and functional activities of brain autonomic centers.     

Effects of sub-acute exposure to static magnetic field on hematologic and biochemical parameters in pregnant rats

This study investigated the effects of a static magnetic field (SMF) on hematopoiesis and biochemical parameters in female rats. Pregnant rats were exposed to SMF (128 mT-1 hour/day from day 6 to day 19 of pregnancy). At 25 degrees C, the exposure of rats 1 hour/day for 13 consecutive days to SMF induced an increase in hematocrit (Ht) level (+6%, p < 0.05), hemoglobin (Hb) concentration (+12%, p < 0.05) and LDH levels (67%, p < 0.05 ), suggesting an hypoxia-like state. Moreover, exposure to SMF increased blood glucose and decreased insulin release, leading to a diabetic-like state in pregnant rats.     

Spindle disturbances in human-hamster hybrid (A(L) ) cells induced by the electrical component of the mobile communication frequency range signal

The production of spindle disturbances in a human–hamster hybrid (A_L) cell line by an electromagnetic field (EMF) with field strength of 90 V/m at a frequency of 900 MHz was studied in greater detail. The experimental setup presented allows investigating whether either the electrical (E) and/or the magnetic (H) field component of EMF can be associated with the effectiveness of the spindle‐disturbing potential. Therefore, both field components of a transversal electromagnetic field (TEM) wave have been separated during exposure of the biological system. This procedure should give more insight on understanding the underlying mechanisms of non‐thermal effects of EMF. A statistical comparison of the proportions of the fractions of ana‐ and telophases with spindle disturbances, obtained for five different exposure conditions with respect to unexposed controls (sham condition), showed that only cells exposed to the H‐field component of the EMF were not different from the control. Therefore, the results of the present study indicate that an exposure of cells to EMF at E‐field strengths of 45 and 90 V/m, as well as to the separated E component of the EMF, induces significant spindle disturbances in ana‐ and telophases of the cell cycle. Bioelectromagnetics 32:291–301, 2011. © 2010 Wiley‐Liss, Inc.     

Artificial static and geomagnetic field interrelated impact on cardiovascular regulation

Spreading evidence suggests that environmental and artificial magnetic fields have a significant impact on cardiovascular system. The modulation of cardiovascular regulatory mechanisms may play a key role in observed effects. The objective was to study interrelated impacts of artificial static magnetic field (SMF) and natural geomagnetic field (GMF) on arterial baroreceptors. We studied baroreflex sensitivity (BRS) in conscious rabbits before and after 40 min of sham (n = 20) or application of Nd2-Fe14-B alloy magnets (n = 26) to the sinocarotid baroreceptor region in conjunction with GMF disturbance during the actual experiment, determined by K- and A(k)-indexes from a local geomagnetic observatory. SMF at the position of baroreceptors was 0.35 T. BRS was estimated from peak responses of mean arterial pressure (MAP) and heart rate expressed as percentages of the resting values preceding each pair of pressure (phenylephrine) and depressor drug (nitroprusside) injections. We observed a significant increase in BRS for the nitroprusside depressor test (0.78 +/- 0.1 vs. 1.15 +/- 0.14 bpm/mmHg%, initial value vs. SMF exposure, P <.0002) and a tendency for phenylephrine pressor test to increase in BRS. Prior to SMF exposure, a significant positive correlation was found between actual K index values and MAP (t = 2.33, P =.025, n = 46) and a negative correlation of the K index with BRS (t = -3.6, P =.001, n = 46). After SMF exposure we observed attenuation of the geomagnetic disturbance induced a decrease in BRS. Clinical trials should be performed to support these results, but there is a strong expectation that 0.35 T SMF local exposure to sinocarotid baroreceptors will be effective in cardiovascular conditions with arterial hypertension and decreased BRS, due to a favorable SMF effect on the arterial baroreflex. Magnets to the sinocarotid triangle along with modification of the pharmacotherapy for hypertension should be especially effective on days with intense geomagnetic disturbance, in moderating sympathetic activation and baroreceptor dysfunction.