EFFECTS OF SINUSOIDAL MAGNETIC FIELD ON ADHERENCE INHIBITION OF LEUKOCYTES

Response of leukocytes to exposure to an external magnetic field with frequency 50 Hz and sinusoidal waveform was investigated in vitro using the leukocyte adherence inhibition (LAI) assay developed as a measure of cell-mediated immunity. Leukocytes taken from healthy humans adhere, but their adherence decreases after 1 hr of exposure to the magnetic field with magnetic induction of 1 and 10 mT. The majority of leukocytes taken from cancer patients before any medical treatment do not adhere, and exposure to the magnetic field increases adherence. Correlation between the LAI assay results and the cell-mediated immunity suggests an effect of magnetic fields on leukocyte immune function in humans.     

Sine Wave Extremely Low Frequency Magnetic Fields Protect Chick Embryos Against UV-Induced Death

Four-day-old chicken embryos were exposed to extremely low frequency (ELF) magnetic fields (MF) prior to UV exposure (75 min, predominantly UV-C, 0.4 mW/cm²) to investigate possible MF-mediated protection against lethal effects of UV. The UV exposure typically resulted in a 20% survival rate (as judged by beating hearts) in sham-exposed embryos 3 h postexposure. In contrast, exposure to a 50 (10, 50, or 100 µT) or 60 Hz (10 µT) vertical MF caused a significant increase in survival rate, observed only 30 min after UV exposure. No difference in protection levels was seen between these exposure intensities. A horizontal 50 Hz MF (10, 50, or 100 µT) did not result in the general protection against UV-induced death observed for vertical fields, suggesting that the size of the induced electric field (which differs between horizontal and vertical exposure) is important for the MF-induced protection. To explore the molecular mechanisms involved in this effect, immunoblotting experiments with an antibody against the inducible form of hsp70 were performed. These showed that application of MF (50 Hz, 200 µT, 1 h) induced hsp70 expression in human K562 cells.     

Magnetic nano-Fe3O4 particles targeted gathering and bio-effects on nude mice loading human hepatoma Bel-7402 cell lines model under external magnetic field exposure in vivo

Abstract

Magnetic nano-Fe₃O₄ particles (MNPs), static magnetic field (SMF) and extremely low-frequency altering electric magnetic field (ELFF) were utilized to treat nude mice loading hepatoma Bel-7402 cell lines to investigate the therapeutic values of MNPs combined with ELFF in vivo. Magnetic resonance image (MRI) figures showed that about 98.9% MNPs injected into mice body through tail vein were gathered in tumor focal by SMF directing exposure. Single ELFF and MNPs treatments did not influence mice physiological function obviously. However, gathered MNPs combined with ELFF treatment prolonged mice survival time and inhibited loading tumor cells proliferation significantly compared to other mice groups (p?<?0.05); furthermore, the tumor cells early apoptosis ratio of mice group was significantly higher than other groups (p?<?0.05), and ELFF combined with gathered MNPs treatment improved tumor cells early apoptosis associated with Bcl group protein expression: Bax protein expression was higher than Bcl-2 and the combined treatment improved cells Heat shock protein-27 (Hsp-27) expression which could protect cells avoiding early apoptosis. The possible mechanism that this kind of combination inducing more cells into early apoptosis could be due to ELFF exposure influencing cells ion metabolism, MNPs strengthening the effects, and the ELFF vibrating MNPs to generate extra heat and activate cellular heat shock signal channel.     

Static magnetic field increases survival rate of dental pulp stem cells during DMSO-free cryopreservation

Abstract

Successful and efficient cryopreservation of living cells and organs is a key clinical application of regenerative medicine. Recently, magnetic cryopreservation has been reported for intact tooth banking and cryopreservation of dental tissue. The aim of this study was to assess the cryoprotective effects of static magnetic fields (SMFs) on human dental pulp stem cells (DPSCs) during cryopreservation. Human DPSCs isolated from extracted teeth were frozen with a 0.4-T or 0.8-T SMF and then stored at ?196?°C for 24?h. During freezing, the cells were suspended in freezing media containing with 0, 3 or 10% DMSO. After thawing, the changes in survival rate of the DPSCs were determined by flow cytometry. To understand the possible cryoprotective mechanisms of the SMF, the membrane fluidity of SMF-exposed DPSCs was tested. The results showed that when the freezing medium was DMSO-free, the survival rates of the thawed DPSCs increased 2- or 2.5-fold when the cells were exposed to 0.4-T or 0.8-T SMFs, respectively (p?<?0.01). In addition, after exposure to the 0.4-T SMF, the fluorescence anisotropy of the DPSCs increased significantly (p?<?0.01) in the hydrophilic region. These results show that SMF exposure improved DMSO-free cryopreservation. This phenomenon may be due to the improvement of membrane stability for resisting damage caused by ice crystals during the freezing procedure.     

Chronic exposure to a 2 mT static magnetic field affects the morphology,the metabolism and the function of in vitro cultured swine granulosa cells

In recent years, the exposure of organisms to static magnetic fields (SMFs) is continuously increasing. Thus, we investigated the effect of chronic exposure to a 2 mT SMF on in vitro cultured swine granulosa cells (GCs). In particular, the culture expansion (cell viability and doubling time), the cell phenotype (cell morphology and orientation, actin and α-tubulin cytoskeleton), the cell metabolism (intracellular Ca²⁺ concentration [Ca²⁺]_i and mitochondrial activity) and the cell function (endocrine activity) were assessed. It has been found that the exposure to the field did not affect the cell viability, but the doubling time was significantly reduced (p < 0.05) in exposed samples after 72 h of culture. At the same time, the cell length and thickness significantly changed (p < 0.05), while the cell orientation was unaffected. Evident modifications were induced on actin and α-tubulin cytoskeleton after 3 days of exposure and, simultaneously, a change in [Ca²⁺]_i and mitochondrial activity started to become evident. Finally, the SMF exposure of GCs longer than 72 h determined a significant alteration of progesterone and estrogen production (p < 0.05). In conclusion, our results demonstrate that the chronic exposure of swine GCs to a 2 mT SMF exerts a negative effect on cell proliferation, morphology, biochemistry and endocrine function in an in vitro model.     

Possible mechanisms of synaptic plasticity modulation by extremely low-frequency magnetic fields

Understanding the biological mechanisms by which extremely low-frequency (ELF, < 300 Hz) magnetic fields (MFs) interact with human brain activity is an active field of research. Such knowledge is required by international agencies providing guidelines for general public and workers exposure to ELF MFs (such as ICNIRP, the International Commission on Non-Ionizing Radiation Protection). The identification of these interaction mechanisms is extremely challenging, since the effects of ELF MF exposure need to be monitored and understood at very different spatial (from micrometers to centimeters) and temporal (from milliseconds to minutes) scales. One possibility to overcome these issues is to develop biophysical models, based on the systems of mathematical equations describing the electric or metabolic activity of the brain tissue. Biophysical models of the brain activity offer the possibility to simulate how the brain tissue interacts with ELF MFs, in order to gain new insights into experimental data, and to test novel hypotheses regarding interaction mechanisms. This paper presents novel hypotheses regarding the effects of power line (60 Hz in North America) MFs on human brain activity, with arguments from biophysical models. We suggest a hypothetic chain of events that could bridge MF exposure with detectable effects on human neurophysiology. We also suggest novel directions of research in order to reach a convergence of biophysical models of brain activity and corresponding experimental data to identify interaction mechanisms.     

Study of the frequency parameters of EEG influenced by zone-dependent local ELF-MF exposure on the human head

It has been reported that human subjects exposed to electromagnetic fields exhibit changes in human EEG signals at the frequency of stimulation. The aim of the present study was to expose different parts of the brain to extremely low-frequency magnetic fields locally and investigate EEG power spectrum alters at the frequency of stimulation. EEG relative power spectrum were evaluated at 3, 5, 10, 17, and 45 Hz frequencies at T4, T3, F3, Cz, and F4 points, respectively, when these points were exposed to magnetic fields with similar frequencies and 100 μT intensity. The paired t-test results showed that power value of EEG did not alter significantly at the frequency of stimulation (P < 0.05). Further, significant changes in different EEG bands caused by locally exposing to ELF-MF in different points of brain were observed. The changes in the EEG bands were not limited necessarily to the exposure point.     

A STUDY OF THE EFFECTS OF STATIC AND EXTREMELY LOW FREQUENCY MAGNETIC FIELDS ON LIPID PEROXIDATION PRODUCTS IN SUBCELLULAR FIBROBLAST FRACTIONS

Cultured fibroblasts isolated from murine livers by tissue trypsinization were exposed to a static magnetic field (0.490 T) and to extremely low frequency (ELF) magnetic field (50 Hz, 0.020 T). The cultures were exposed to magnetic fields on four consecutive days for exposure times of 2, 4, 8, 16, 32, and 64 min. After such exposures and obtaining of fibroblast subcellular fractions, lipid peroxidation product—malondialdehyde (MDA) was measured. Increased peroxidation of fibroblasts' membrane structures exposed to an ELF magnetic field was observed in subcellular fractions—microsomal, mitochondrial, and nuclear. No changes in peroxidation of membrane structures were found in fibroblasts exposed to a static magnetic field.     

Volumetric properties underlying ligand binding in a monomeric hemoglobin: A high-pressure NMR study

The 2/2 hemoglobin of the cyanobacterium Synechococcus sp. PCC 7002, GlbN, coordinates the heme iron with two histidines and exists either with a b heme or with a covalently attached heme. The binding of exogenous ligands displaces the distal histidine and induces a conformational rearrangement involving the reorganization of internal void volumes. The formation of passageways within the resulting conformation is thought to facilitate ligand exchange and play a functional role. Here we monitored the perturbation induced by pressure on the ferric bis-histidine and cyanide-bound states of GlbN using ¹H–¹⁵N HSQC NMR spectroscopy. We inspected the outcome with a statistical analysis of 170 homologous 2/2 hemoglobin sequences. We found that the compression landscape of GlbN, as represented by the variation of an average chemical shift parameter, was highly sensitive to ligand swapping and heme covalent attachment. Stabilization of rare conformers was observed at high pressures and consistent with cavity redistribution upon ligand binding. In all states, the EF loop was found to be exceptionally labile to pressure, suggesting a functional role as a semi-flexible hinge between the adjacent helices. Finally, coevolved clusters presented a common pattern of compensating pressure responses. The high-pressure dissection combined with protein sequence analysis established locations with volumetric signatures relevant to residual communication of 2/2 hemoglobins. This article is part of a Special Issue entitled: Oxygen Binding and Sensing Proteins.     

Catheter ablation in children and young adults: is there an additional benefit from remote magnetic navigation?

Purpose

Although rare, children and young adults can suffer from significant cardiac arrhythmia, especially in the context of congenital malformations and after cardiac surgery.

Methods

A total of 62 patients (32 female, median age 20 years) underwent an invasive electrophysiology study between 2008–2011: half had normal cardiac anatomy, whereas the remaining patients had various types of congenital heart disease. All patients were treated using either conventional techniques (CVN) or remote magnetic navigation (RMN).

Results

Patients treated with the RMN system differed substantially from patients in the CVN group with respect to presence of congenital heart disease (67 % vs. 37 %), previous cardiac surgery (59 % vs. 20 %) or failed previous conventional ablation (22 % vs. 9 %), respectively. Although these more complex arrhythmias resulted in longer median procedure duration (180 vs. 130 min, p = 0.034), the median overall fluoroscopy exposure in the RMN group was significantly lower (4.1 vs. 5.2 min, p = 0.020). Clinical outcome was comparable in both groups without complications caused by the ablation.

Conclusions

Catheter ablation using remote magnetic navigation is safe and feasible in children and young adults and is especially valuable in patients with abnormal cardiac morphologies. RMN resulted in significantly lower radiation exposure compared with the conventional technique.