iMRS 2000 - PEMF Publications
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301

Effects of 50 Hz electromagnetic fields on rat cortical synaptosomes

Nerve cells are very responsive to weak pulsed electromagnetic fields (EMFs). Such non-ionizing radiation, with frequencies of 0-300 Hz and 0.1-100 mT, can affect several cellular activities, with unusual dose-response characteristics. The present study examined the effect of a 2-h exposure of synaptosomes on a system generating a peak magnetic field of 2 mT. We evaluated the changes of the synaptosomal mitochondrial respiration rate and ATP production, membrane potential, intrasynaptosomal Ca2+ concentration, and the release of free iron and F2-isoprostanes. O2 consumption and ATP production remained unchanged in exposed synaptosomes. The intrasynaptosomal Ca2+ concentration decreased slowly and no depolarization of the synaptosomal membrane was detected. Finally, the release of free iron and F2-isoprostanes by synaptosomal suspensions also remained unchanged after EMF exposure. These results indicate that the physiological behavior of cortical synaptosomes was unaffected by weak pulsed EMFs.

302

Effects of 915 MHz electromagnetic-field radiation in TEM cell on the blood-brain barrier and neurons in the rat brain

The aim of this study was to determine whether albumin leakage and dark neurons were present in rat brains 14 and 50 days after a single 2-h exposure to a 915 MHz electromagnetic field, as reported by Salford et al. (Environ. Health Perspect. 111, 881-883, 203). Sixty-four male F344 rats (12 weeks old) were exposed to a 915 MHz electromagnetic field at whole-body average specific absorption rates of 0, 0.02, 0.2 and 2.0 W/kg in TEM cells for 2 h, following the protocol reported by Salford et al. The brains were examined histologically and immunohistochemically. No albumin immunoreactivity was observed in the exposed groups. In addition, dark neurons, assessed using hematoxylin and eosin staining, were rarely present, with no statistically significant difference between exposed and sham-exposed animals. This study thus failed to confirm the results of Salford et al.

303

Effects of a pulsed electromagnetic field on a mixed chondroblastic tissue culture

A mixed tissue culture predominantly composed of chondroblastic tissue was perturbed by a pulsed electromagnetic field (PEMF). Some cultures were nonconfluent, and purposely retarded in growth to resemble an atrophic nonunion, while others were grown to confluence in about one-half the time as a model for a hypertrophic nonunion. These two groups tested the effect of growth rate upon the products of cell proliferation and differentiation. The slowly growing cultures were stimulated to synthesize hydroxyproline. The rapidly growing cultures showed a large increase in lysozyme activity, and increase in hyaluronate and DNA, and a decrease in glycosaminoglycan. Exogenous lysozyme further decreased the glycosaminoglycan synthesis in the presence of PEMF. Chitotriose, a specific lysozyme inhibitor abolished this effect. Cycloheximide, a protein synthesis inhibitor, did not abolish the activation of lysozyme found in the matrix. Thus lysozyme appears to be activated by PEMF. These observations of the rapidly growing confluent cultures are consistent with events described in the normal healing of a bone fracture or endochrondral growth. Thus, PEMF appears to promote normal healing, probably by altering cartilaginous lysozyme activity in the matrix, and possibly the sequence of events leading to calcification.

304

Effects of a pulsed electromagnetic therapy on multiple sclerosis fatigue and quality of life: a double-blind, placebo controlled trial

CONTEXT: There is a growing literature on the biological and clinical effects of pulsed electromagnetic fields. Some studies suggest that electromagnetic therapies may be useful in the treatment of chronic illnesses. This study is a follow-up to a placebo controlled pilot study in which multiple sclerosis (MS) patients exposed to weak, extremely low frequency pulsed electromagnetic fields showed significant improvements on a composite symptom measure. OBJECTIVE: To evaluate the effects of a pulsed electromagnetic therapy on MS related fatigue, spasticity, bladder control, and overall quality of life. DESIGN: A multi-site, double-blind, placebo controlled, crossover trial. Each subject received 4 weeks of the active and placebo treatments separated by a 2-week washout period. SETTING: The University of Washington Medical Center in Seattle Wash, the Neurology Center of Fairfax in Fairfax, Va, and the headquarters of the Multiple Sclerosis Association of America in Cherry Hill, NJ. SUBJECTS: 117 patients with clinically definite MS. INTERVENTION: Daily exposure to a small, portable pulsing electromagnetic field generator. MAIN OUTCOME: The MS Quality of Life Inventory (MSQLI) was used to assess changes in fatigue, bladder control, spasticity, and a quality of life composite. RESULTS: Paired t-tests were used to assess treatment differences in the 117 subjects (81% of the initial sample) who completed both treatment sessions. Improvements in fatigue and overall quality of life were significantly greater on the active device. There were no treatment effects for bladder control and a disability composite, and mixed results for spasticity. CONCLUSIONS: Evidence from this randomized, double-bind, placebo controlled trial is consistent with results from smaller studies suggesting that exposure to pulsing, weak electromagnetic fields can alleviate symptoms of MS. The clinical effects were small, however, and need to be replicated. Additional research is also needed to examine the possibility that ambulatory patients and patients taking interferons for their MS may be most responsive to this kind of treatment.

305

Effects of a static magnetic field on wound healing: results in experimental rat colon anastomoses

BACKGROUND: Research has shown that pulsed electromagnetic fields (EMFs) promote wound healing in experimental colonic anastomosis; however, the effects of static EMFs in this setting have not been investigated to date. METHODS: Fifty male Wistar rats were used. Ten served as controls for mechanical strength testing, and the other 40 underwent descending colon resection and anastomosis. Twenty of these 40 animals (M group) had NeFeB magnets placed in contact with the anastomosis site (magnetic field strength at the site 390 to 420 G). The other 20 animals (sham [S] group) had non-magnetized NeFeB bars of the same dimensions and weight implanted. Half of the animals in each group were killed and assessed for healing parameters on postoperative day 3 (M3 and S3 groups) and the other half on postoperative day 7 (M7 and S7 groups). Four types of assessment were done: gross healing, mechanical strength, hydroxyproline deposition, and histopathology. RESULTS: There were no differences between the M and S animals with respect to gross healing parameters. The mechanical strength was also not different between groups (23.8 +/- 12.7 and 24.7 +/- 9.6 mm Hg for M3 and S3, respectively; P = .863 and 91.3 +/- 65.4 and 94.8 +/- 55.9 mm Hg for M7 and S7, respectively; P = .902). Similarly, hydroxyproline deposition was not different between groups on postoperative day 3 or day 7. On postoperative day 3, the M group had significantly higher scores than the S group for fibroblast infiltration (2.4 +/- 0.7 vs 1.4 +/- 0.7, respectively; P = .008) and capillary formation (2.5 +/- 0.7 vs 0.9 +/- 0.4, respectively; P <.001). However, these effects were reversed and did not endure by day 7. CONCLUSIONS: The study results suggest that static EMF has no effect on experimental colonic wound healing in the rat.

307

Effects of And50 Hz sinusoidal magnetic fileds on Hsp27, Hsp70, Hsp90 expression in porcine aortic endothelial cells

Extremely low frequency (ELF) magnetic fields (MF) increase in the mRNA levels of all three proteins, Hsp27, Hsp70, Hsp90, but this was statistically significant for Hsp70 only. The authors did not, however, observed any influence on Hsp27, Hsp70, and Hsp90 protein levels. They chose porcine aortic endothelial cells because endothelial cells are involved in the onset of many diseases.

308

Effects of astigmatism on spectra, coherence and polarization of stochastic electromagnetic beams passing through an astigmatic optical system

Analytical formulas for the cross-spectral density matrix of stochastic electromagnetic Gaussian Schell-model (EGSM) beams passing through an astigmatic optical system are derived. We show both analytically and by numerical examples the effects of astigmatism on spectra, coherence and polarization of stochastic electromagnetic EGSM beams propagating through an astigmatic lens. A comparison with the aberration-free case is made, and shows that the astigmatism has significant effect on the spectra, coherence and polarization.

309

Effects of biophysical stimulation in patients undergoing arthroscopic reconstruction of anterior cruciate ligament: prospective, randomized and double blind study

Pre-clinical studies have shown that treatment by pulsed electromagnetic fields (PEMFs) can limit the catabolic effects of pro-inflammatory cytokines on articular cartilage and favour the anabolic activity of the chondrocytes. Anterior cruciate ligament (ACL) reconstruction is usually performed by arthroscopic procedure that, even if minimally invasive, may elicit an inflammatory joint reaction detrimental to articular cartilage. In this study the effect of I-ONE PEMFs treatment in patients undergoing ACL reconstruction was investigated. The study end-points were (1) evaluation of patients' functional recovery by International Knee Documentation Committee (IKDC) Form; (2) use of non-steroidal anti-inflammatory drugs (NSAIDs), necessary to control joint pain and inflammation. The study design was prospective, randomized and double blind. Sixty-nine patients were included in the study at baseline. Follow-up visits were scheduled at 30, 60 and 180 days, followed by 2-year follow-up interview. Patients were evaluated by IKDC Form and were asked to report on the use of NSAIDs. Patients were randomized to active or placebo treatments; active device generated a magnetic field of 1.5 mT at 75 Hz. Patients were instructed to use the stimulator (I-ONE) for 4 h per day for 60 days. All patients underwent ACL reconstruction with use of quadruple hamstrings semitendinosus and gracilis technique. At baseline there were no differences in the IKDC scores between the two groups. At follow-up visits the SF-36 Health Survey score showed a statistically significant faster recovery in the group of patients treated with I-ONE stimulator (P < 0.05). NSAIDs use was less frequent among active patients than controls (P < 0.05). Joint swelling resolution and return to normal range of motion occurred faster in the active treated group (P < 0.05) too. The 2-year follow-up did not shown statistically significant difference between the two groups. Furthermore for longitudinal analysis the generalized linear mixed effects model was applied to calculate the group x time interaction coefficient; this interaction showed a significant difference (P < 0.0001) between the active and placebo groups for all investigated variables: SF-36 Health Survey, IKDC Subjective Knee Evaluation and VAS. Twenty-nine patients (15 in the active group; 14 in the placebo group) underwent both ACL reconstruction and meniscectomy; when they were analysed separately the differences in SF-36 Health Survey scores between the two groups were larger then what observed in the whole study group (P < 0.05). The results of this study show that patient's functional recovery occurs earlier in the active group. No side effects were observed and the treatment was well tolerated. The use of I-ONE should always be considered after ACL reconstruction, particularly in professional athletes, to shorten the recovery time, to limit joint inflammatory reaction and its catabolic effects on articular cartilage and ultimately for joint preservation.

310

Effects of BMP-2 and pulsed electromagnetic field (PEMF) on rat primary osteoblastic cell proliferation and gene expression

Bone morphogenetic proteins (BMPs) strongly promote osteoblast differentiation. Pulsed electromagnetic fields (PEMFs) promote fracture healing in non-union fractures. In this study, we hypothesized that a combined BMP-2 and PEMF stimulation would augment bone formation to a greater degree than treatment with either single stimulus. BMP-2 maximally increased the proliferative activity of rat primary osteoblastic cells at 25 ng/ml concentration. Real-time reverse transcription-polymerase chain reaction (RT-PCR) showed that BMP-2 stimulated mRNA levels of alkaline phosphatase (ALP), alpha(1) (I) procollagen, and osteocalcin (OC) in the differentiation phase and only OC mRNA expression in the mineralization phase after 24-h treatment. Both BMP-2 and PEMF (Spinal-Stim) increased cell proliferation, which was additive when both agents were combined. PEMF alone or together with BMP-2 increased only ALP mRNA expression and only during the differentiation phase 24 h after one 4-h treatment. This effect was additive when both agents were combined. Continuous daily 4-h treatment with PEMF alone or together with BMP-2 increased expression of all three osteoblast marker genes during the differentiation phase and increased the mineralized matrix. This effect was additive when both agents were combined, suggesting that the two interventions may be working on different cellular pathways. Thus, a combined effect of BMP-2 and PEMF in vitro could be considered as groundwork for in vivo bone development that may support skeletal therapy.

311

Effects of combined exposure of micrococcus luteus to nisin and pulsed electric fields

Death and injury following exposure of Micrococcus luteus to nisin and pulsed electric field (PEF) treatment were investigated in phosphate buffer (pH 6.8, sigma = 4.8 ms/cm at 20 degrees C). Four types of experiment were carried out, a single treatment with nisin (100 IU/ml at 20 degrees C for 2 h), a single PEF treatment, a PEF treatment followed by incubation with nisin (as before) and addition of nisin to the bacterial suspension prior to the PEF treatment. The application of nisin clearly enhanced the lethal effect of PEF treatment. The bactericidal effect of nisin reduced viable counts by 1.4 log10 units. Treatment with PEF (50 pulses at 33 kV/cm) resulted in a reduction of 2.4 log10 units. PEF treatment followed by nisin caused a reduction of 5.2 log10 units in comparison with a 4.9 log10 units reduction obtained with nisin followed by PEF. Injury of surviving cells was investigated using media with different concentrations of salt. Sublethally damaged cells of M. luteus could not be detected by this means, following PEF treatment.

312

Effects of different extremely low-frequency electromagnetic fields on osteoblasts

It is well known that the extremely low-frequency electromagnetic field (EMF) can promote the healing of bone fractures, but its mechanism remains poorly understood. The purpose of this study was to examine the response of neonatal rat calvarial bone cells to the rectangular electromagnetic field (REMF), triangular electromagnetic field (TEMF), sinusoidal electromagnetic field (SEMF), and pulsed electromagnetic field (PEMF). The stimulatory effects of EMF were evaluated by the proliferation (methyltetrazolium colorimetric assay), differentiation (alkaline phosphatase (ALP) activity), and mineralization (area of mineralized nodules of the cells). REMF treatment of osteoblasts increased cellular proliferation and decreased ALP activity (p < 0.05). TEMF had an accelerative effect on the cellular mineralized nodules (p < 0.05). SEMF treatment of osteoblasts decreased the cellular proliferation, increased ALP activity, and suppressed mineralized nodules formation (p < 0.05). PEMF promoted the proliferation of osteoblasts, inhibited their differentiation, and increased the mineralized nodules formation (p < 0.05). Moreover, the effects of PEMF on osteoblasts were concerned with the extracellular calcium, P2 receptor on the membrane, and PLC pathway, but the response of osteoblasts on SEMF was only related to PLC pathway. The results suggested that the waveforms of EMF were the crucial parameters to induce the response of osteoblasts.

313

Effects of different intensities of extremely low frequency pulsed electromagnetic fields on formation of osteoclast-like cells

Over the past 30 years, the beneficial therapeutic effects of selected low energy, time varying electromagnetic fields (EMF) have been documented with increasing frequency to treat therapeutically resistant problems of the musculoskeletal system. However, the underlying mechanisms at a cellular level are still not completely understood. In this study, the effects of extremely low frequency pulsed electromagnetic fields (ELF-PEMF) on osteoclastogenesis, cultured from murine bone marrow cells and stimulated by 1,25(OH)(2)D(3), were examined. Primary bone marrow cells were cultured from mature Wistar rats and exposed to ELF-PEMF stimulation daily for 7 days with different intensities of induced electric field (4.8, 8.7, and 12.2 micro V/cm rms) and stimulation times (0.5, 2, and 8 h/day). Recruitment and authentication of osteoclast-like cells were evaluated, respectively, by determining multinuclear, tartrate resistant acid phosphatase (TRAP) positive cells on day 8 of culture and by the pit formation assay. During the experiments, cytokines such as tumor necrosis factor-alpha (TNF-alpha), interleukin 1-beta (IL-1beta), and prostaglandin-E(2) (PGE(2)) were assayed using the enzyme linked immunosorbent assay (ELISA). These findings suggest that ELF-PEMF can both enhance (approximately 50%) and suppress (approximately 27%) the formation of osteoclast-like cells in bone marrow culture, depending on the induced electric field intensity. In addition, consistent correlations were observed between TNF-alpha, IL-1beta, and osteoclast-like cell number after exposure to different induced electric field intensities of ELF-PEMF. This in vitro study could be considered as groundwork for in vivo ELF-PEMF clinical applications on some osteoclast-associated bone diseases.

314

Effects of Different Intensities of Extremely Low Frequency Pulsed Electromagnetic Fields on Formation of Osteoclast-Like Cells

When PEMFs are applied there were inherent correlations between the formation of osteoclast-like cells and cytokines. The authors assert that PEMFs may be an effective treatment for osteoporosis, and conversely, for osteopetrosis, using different electric field intensities on bone.

316

Effects of electromagnetic field on bone healing around commercially pure titanium surface: histologic and mechanical study in rabbits

PURPOSE: The purpose of this pilot study was to evaluate the histologic and mechanical healing process in dental implants under the action of pulsed electromagnetic field (PEMF). MATERIALS AND METHODS: Forty-eight commercially pure implant fixtures were implanted in tibiae metaphysis of 12 New Zealand white rabbits divided into experimental (PEMF) and control groups. A PEMF with pulse width of 85 microseconds and a pulse frequency of 20 Mc was applied for 30 minutes per day. The animals were killed 21 and 42 days after implantation. The mechanical tests were performed in all animals and bone biopsies were prepared for decalcified sections analysis. RESULTS: Mechanical tests did not show significant differences between the groups (P > 0.05); however, statistically significant differences were observed over time (P < 0.0001). Similar histologic features were achieved for both groups. CONCLUSIONS: These results suggest that PEMF stimulation does not improve the bone-healing process around commercially pure dental implants.

317

Effects of electromagnetic fields on fecundity in the chicken

Egg production was reduced when young laying hens were kept in contact with metal cages while being continuously exposed to the following cw fields: a vhf field at a frequency of 260 MHz, with an incident power that decreased from 100 to 4mW during the experiment; a uhf field at a frequency of 915 MHz, with an incident power of 800 mW during the first 2.5 weeks, zero during the following week, and 200 mW for the remainder of the experiment; a uhf field at 2.435 GHz, with an incident power of 800 mW; an elf electric field at a frequency of 60 Hz, with a calculated value of field strength of 1600 V/m; an elf magnetic field at 60 Hz, with a value of magnetic flux density of 1.4G. With the exception of the hens exposed to the uhf field at 915 MHz, all other treated groups laid significantly less eggs than the controls (p smaller than or equal to 0.01). This reduction (similar 15% less than the controls) began with the first 4-week production period. The egg production curves for the hens exposed to the vhf field at 260 MHz and to the uhf field at 2.435 GHz were approximately the same beginning with the sixth week of production, and they maintained comparable production levels for the remainder of the experiment. An 8% total drop in production also was experienced in the group of birds exposed to the 915-MHz field, which pulsed because of equipment failure. Egg production rate curves for the birds in the elf electric and magnetic fields were substantially different from those exhibited by birds in the other electromagnetic fields. The birds in the E-field regained a production level comparable to the controls after 11 weeks production, whereas those in the B-field dropped to 31% production, which was approximately 40% poorer than the controls by the twelfth week of production. Fertility of cocks and hens was not affected by continuous low-power vhf and uhf near-zone electromagnetic exposure or elf electric or magnetic field treatment. Fertility was exceptionally good, except for the controls and the hens exposed to the elf electric field. The hatchs of fertile and of total eggs were not significantly influenced by exposure to any of the five fields. A considerably lower incidence of male chicks was noted in the elf magnetic field treatment (32.3%). The sex ratio in the other groups appeared to be relatively normal. No macroscopic abnormalities attributable to treatments were noted in the chicks hatched or in the dead embryos.

318

Effects of electromagnetic stimulation on the functional responsiveness of isolated rat osteoclasts

We report the effects of pulsed electromagnetic fields (PEMFs) on the responsiveness of osteoclasts to cellular, hormonal, and ionic signals. Osteoclasts isolated from neonatal rat long bones were dispersed onto either slices of devitalised cortical bone (for the measurement of resorptive activity) or glass coverslips (for the determination of the cytosolic free Ca2+ concentration, [Ca2+]). Osteoclasts were also cocultured on bone with osteoblastlike, UMR-106 cells. Bone resorption was quantitated by scanning electron microscopy and computer-assisted morphometry. PEMF application to osteoblast-osteoclast cocultures for 18 hr resulted in a twofold stimulation of bone resorption. In contrast, resorption by isolated osteoclasts remained unchanged in the presence of PEMFs, suggesting that osteoblasts were necessary for the PEMF-induced resorption simulation seen in osteoblast-osteoclast cocultures. Furthermore, the potent inhibitory action of the hormone calcitonin on bone resorption was unaffected by PEMF application. However, PEMFs completely reversed another quite distinct action of calcitonin on the osteoclast: its potent inhibitory effect on the activation of the divalent cation-sensing (or Ca2+) receptor. For these experiments, we made fura 2-based measurements of cytosolic [Ca2+] in single osteoclasts in response to the application of a known Ca2+ receptor agonist, Ni2+. We first confirmed that activation of the osteoclast Ca2+ receptor by Ni2+ (5 mM) resulted in a characteristic monophasic elevation of cytosolic [Ca2+]. As shown previously, this response was attenuated strongly by calcitonin at concentrations between 0.03 and 3 nM but remained intact in response to PEMFs. PEMF application, however, prevented the inhibitory effect of calcitonin on Ni2+-induced cytosolic Ca2+ elevation. This suggested that the fields disrupted the interaction between the calcitonin and Ca2+ receptor systems. In conclusion, we have shown that electromagnetic fields stimulate bone resorption through an action on the osteoblast and, by abolishing the inhibitory effects of calcitonin, also restore the responsiveness of osteoclasts to divalent cations.

319

Effects of electromagnetic stimuli on bone and bone cells in vitro: inhibition of responses to parathyroid hormone by low-energy low-frequency fields

Low-energy electromagnetic fields pulsed at frequencies of 10-90 Hz significantly increase healing of chronic fracture nonunions in man. These fields are effective at tissue current levels several orders of magnitude lower than those required for transmembrane depolarization of normal cells. We have examined the effects of two clinically used pulsed electromagnetic fields on cultures of the osteoblast-like mouse bone cell line MMB-1. Both fields significantly reduced cellular production of cAMP in response to parathyroid hormone and osteoclast activating factor. Neither basal nor fluoride-activated levels of adenylate cyclase were altered in membranes from cells cultured in the fields; however, the same membrane preparations exhibited markedly inhibited responses to parathyroid hormone. The fields blocked the inhibitory effects of the hormone on collagen synthesis by MMB-1 cells. However, there was no effect on the inhibition of collagen synthesis by 1,25-dihydroxyvitamin D(3), which is believed to act primarily by a nuclear, rather than by a membrane-dependent, mechanism. No significant differences were noted between effects of the two fields, one generating continuous pulse trains (72 Hz) and the other generating recurrent bursts (15 Hz) of shorter pulses. We hypothesize that these field effects are mediated primarily at the plasma membrane of osteoblasts, either by interference with hormone-receptor interactions or by blocking of receptor-cyclase coupling in the membrane. These responses occurred with induced extracellular fields of 1 mV/cm or less, even though transmembrane potential gradients are typically 10(5) V/cm.

320

Effects of Extremely Low Frequency Electromagnetic Field (EMF) on Collagen Type I mRNA Expression and Extracellular Matrix Synthesis of Human Osteoblastic Cells

EMFs And expression of the collagen type I mRNA gene which may lead to increased synthesis of extensive extracellular matrix collagen.

321

Effects of extremely-low-frequency pulsed electromagnetic fields on collagen synthesis in rat skin

To investigate the effects of extremely-low-frequency PEMFs (pulsed electromagnetic fields) on the synthesis of epidermal collagen, six groups of animals each consisting of eight mature male rats were selected randomly: one group for the control and five for the test. Using a parallel set of Helmholtz coils, a uniform field intensity of 2 mT at different frequencies of 25, 50 and 100 Hz yielded the most effective frequency to be 25 Hz. Then, at this frequency, two different field intensities of 1 and 4 mT were applied. The treatment time of 2.5 h/day lasted for 8 days, keeping the same procedure for the control group, except with the field turned off. On the ninth day, the rats were killed and skin samples from the dorsal region were taken for collagen assessment by measuring hydroxyproline content using the Stegemann-Stalder [(1967) Clin. Chim. Acta 8, 267-273] method. The results indicated that a PEMF of 2 mT at 25 Hz increased the collagen synthesis (P < 0.05). The other intensities and frequency setting did not have any noticeable effect; however, at a frequency of 25 Hz at 4 mT, collagen increase was also noticed. It was concluded that at 25 Hz under a field setting of 2 mT for the duration of 8 days, stimulation of skin at 2.5 h/day would cause increase in collagen synthesis in rat skin.

322

Effects of gestational exposure to a video display terminal-like magnetic field (20-kHz) on CBA/S mice

Possible adverse effects of magnetic fields (MFs) on reproduction have been an open question. To verify the embryo-lethal effect of pulsed MF of the type emitted by video display terminals (VDTs) reported previously in CBA/S mice, a developmental toxicity study was conducted in animals of the same origin. Mated CBA/S mice (80-86 pregnant animals per group) were exposed to a 20-kHz MF with sawtooth waveform continuously from gestational day 0-18. The flux density of the vertical MF was 15 microT peak-to-peak (150 mG). This field was previously reported to increase the number of resorptions in CBA/S mice. On gestational day 18, the dams were killed and blood and bone marrow samples were taken for hematology and micronuclei analysis, respectively. The number of corpora lutea was counted and the content of the uterus examined. There were no statistically significant differences in maternal or fetal body weights, number of corpora lutea, implantations, resorptions, dead and live fetuses, or external and skeletal malformations. MF did not alter the number of blood cells or cause micronuclei in bone marrow erythrocytes in the dams. The mean number of resorptions was slightly but not statistically significantly, higher in the MF group than in controls. The results do not indicate marked developmental, hematological, or clastogenic effects of 20-kHz MFs.

323

Effects of high frequency electromagnetic field (EMF) emitted by mobile phones on the human motor cortex

We investigated whether the pulsed high frequency electromagnetic field (EMF) emitted by a mobile phone has short term effects on the human motor cortex. We measured motor evoked potentials (MEPs) elicited by single pulse transcranial magnetic stimulation (TMS), before and after mobile phone exposure (active and sham) in 10 normal volunteers. Three sites were stimulated (motor cortex (CTX), brainstem (BST) and spinal nerve (Sp)). The short interval intracortical inhibition (SICI) of the motor cortex reflecting GABAergic interneuronal function was also studied by paired pulse TMS method. MEPs to single pulse TMS were also recorded in two patients with multiple sclerosis showing temperature dependent neurological symptoms (hot bath effect). Neither MEPs to single pulse TMS nor the SICI was affected by 30 min of EMF exposure from mobile phones or sham exposure. In two MS patients, mobile phone exposure had no effect on any parameters of MEPs even though conduction block occurred at the corticospinal tracts after taking a bath. As far as available methods are concerned, we did not detect any short-term effects of 30 min mobile phone exposure on the human motor cortical output neurons or interneurons even though we can not exclude the possibility that we failed to detect some mild effects due to a small sample size in the present study. This is the first study of MEPs after electromagnetic exposure from a mobile phone in neurological patients.

325

Effects of high-frequency electromagnetic fields on human EEG: a brain mapping study

Cell phones emitting pulsed high-frequency electromagnetic fields (EMF) may affect the human brain, but there are inconsistent results concerning their effects on electroencephalogram (EEG). We used a 16-channel telemetric electroencephalograph (ExpertTM), to record EEG changes during exposure of human skull to EMF emitted by a mobile phone. Spatial distribution of EMF was especially concentrated around the ipsilateral eye adjacent to the basal surface of the brain. Traditional EEG was full of noises during operation of a cellular phone. Using a telemetric electroencephalograph (ExpertTM) in awake subjects, all the noise was eliminated, and EEG showed interesting changes: after a period of 10-15 s there was no visible change, the spectrum median frequency increased in areas close to antenna; after 20-40 s, a slow-wave activity (2.5-6.0 Hz) appeared in the contralateral frontal and temporal areas. These slow waves lasting for about one second repeated every 15-20 s at the same recording electrodes. After turning off the mobile phone, slow-wave activity progressively disappeared; local changes such as increased median frequency decreased and disappeared after 15-20 min. We observed similar changes in children, but the slow-waves with higher amplitude appeared earlier in children (10-20 s) than adults, and their frequency was lower (1.0-2.5 Hz) with longer duration and shorter intervals. The results suggested that cellular phones may reversibly influence the human brain, inducing abnormal slow waves in EEG of awake persons.

326

Effects of high-peak pulsed electromagnetic field on the degeneration and regeneration of the common peroneal nerve in rats

Apart from preliminary notices of present work, previous reports of experimental and clinical trials of the effects of a high-peak pulsed electromagnetic field (PEMF) on degeneration and regeneration of peripheral nerves lacked statistical analysis. Therefore, we designed experiments with standardised operative, histological, cytological and morphometric techniques to assess the effect of PEMF on lesions of the common peroneal nerves in paired male rats matched for age, environmental conditions and level and type of lesion. One of two types of lesion was induced in the left common peroneal nerve: in 12 pairs of rats the nerve was crushed just above the knee and in the remaining 12 pairs the nerve was cut and immediately sutured at the same level. The right common peroneal nerve of each rat served as a control. Animals received 15 minutes of PEMF produced by a Diapulse machine or sham treatment daily for periods ranging from three and a half days to eight weeks after injury. Healthy nerves were unaffected, but after damage there were statistically significant differences between PEMF treated and sham treated rats. PEMF accelerated the recovery of injured limbs and the degeneration, regeneration and maturation of myelinated axons; epineural, perineural and intraneural fibrosis was reduced; and the luminal cross-sectional area of intraneural vessels increased after both types of lesion. Findings are discussed and the need for clinical trials is stressed.

327

Effects of hypomagnetic field on noradrenergic activities in the brainstem of golden hamster

Previous studies found that elimination of the geomagnetic field (GMF) interferes with the normal brain functions, but the underlying mechanism remains unknown. The present study examined the effects of long-term exposures to a near-zero magnetic environment on the noradrenergic activities in the brainstem of golden hamsters. Both the content of norepinephrine (NE) and the density of NEimmunopositive neurons in the tissue decreased significantly after the treatment, and the effects could be progressive with time. These variations may substantially contribute to behavioral and mood disorders reported in other studies when animals are shielded from the GMF. Bioelectromagnetics 28:155–158, 2007.

328

Effects of localised, low-voltage pulsed electric fields on the development and inhibition of Pseudomonas aeruginosa biofilms

This work describes the use of low-voltage (0.5 - 5 V) pulsed electric fields to prevent Pseudomonas aeruginosa biofilm development. Interdigitated electrodes (IDEs) with 29-mum spacing between 22-mum-wide electrodes, were used as a platform where the effect of localised, high-strength electric fields could be tested. Alternating current, square-wave pulses were applied to the IDEs in 1 sec intervals. A two-level, three-variable factorial design experiment was used to detect the effects of applied voltage, frequency, and pulse duty ratio (i.e. percentage of pulsing time over one cycle) on the inhibition of biofilm formation. The observations indicated that a pulse configuration of 1% duty ratio, 5 V, and 200 Hz frequency reduced the area of the electrodes covered by biofilm by 50%. In general, the application of low-duty ratio pulses had a positive effect on preventing biofouling. Comparatively, frequency and applied voltage were observed to have less influence on biofouling.

329

Effects of low frequency pulsed electrical current on keratinocytes in vitro

The effects of low frequency pulsed electrical current on epidermal repair in vitro were examined. Charge-balance current stimuli proposed for chronic wound treatment were tested on skin keratinocytes cultured at an air-liquid interface on dead human dermis. Results imply that the balance between proliferation and differentiation in electrically treated samples is significantly modified in favor of differentiation. More advanced differentiation, shown through epidermal histology, was obtained in cultures exposed to electrical current, whereas the culture growth, the result of keratinocyte migration and proliferation, was greater in control samples.

330

Effects of low-amplitude pulsed magnetic fields on cellular ion transport

Pulsed magnetic fields (PMFs) are widely used to treat difficult fractures of bone and other disorders of connective tissue. It is not clear how they interact with tissue metabolism, although it has been proposed that induced currents or electric fields impinging on cell membranes may modify their ion transport function. This hypothesis was tested by treating in vitro models for ion transport processes with short-term exposure to PMFs. No change occurred in active transport of potassium or calcium in human red cells or in calcium transport through an epithelial membrane. We considered less direct action on red cell membranes, that their permeability might be modified after PMF treatment, and also that PMFs might alter the extracellular ionic activity within connective tissue by interacting with its Donnan potential. Each of these studies proved negative, and we conclude that the PMF waveforms used here do not exert a general short-term effect on cellular ion transport.

331

Effects of low-energy electromagnetic fields (pulsed and DC) on membrane signal transduction processes in biological systems

The vertebrate organism possesses a number of internal processes for signaling and communication between cell types. Hormones and neurotransmitters move from one cell type to another and carry chemical "messages" that modulate the metabolic responses of tissues to the environment. Interaction with these signaling systems is a potential mechanism by which very low-energy electromagnetic fields might produce metabolic responses in the body. Hormone and neurotransmitter receptors are specialized protein molecules that use a variety of biochemical activities to pass chemical signals from the outside of a cell across the plasma membrane to the interior of the cell. Since many low-energy electromagnetic fields have too little energy to directly traverse the membrane, it is possible that they may modify the existing signal transduction processes in cell membranes, thus producing both transduction and biochemical amplification of the effects of the field itself. As an example of the kinds of processes that may be involved in these interactions, one metabolic process in which the physiological effects of low-energy electromagnetic fields is well established is the healing of bone fractures. The process of regulation of bone turnover and healing is reviewed in the context of clinical applications of electromagnetic energy to the healing process, especially for persistent nonunion fractures. A hypothetical molecular mechanism is presented that might account for the observed effects of electromagnetic fields on bone cell metabolism in terms of the fields' interference with signal transduction events involved in the hormonal regulation of osteoblast function and differentiation.

332

Effects of low-intensity pulsed electromagnetic fields on the early development of sea urchins

The effects of weak electromagnetic signals on the early development of the sea urchin Paracentrotus lividus have been studied. The duration and repetition of the pulses were similar to those used for bone healing in clinical practice. A sequence of pulses, applied for a time ranging from 2 to 4 h, accelerates the cleavages of sea urchin embryo cells. This effect can be quantitatively assessed by determining the time shifts induced by the applied electromagnetic field on the completion of the first and second cleavages in a population of fertilized eggs. The exposed embryos were allowed to develop up to the pluteus stage, showing no abnormalities.

333

Effects of mobile phone type signals on calcium levels within human leukaemic T-cells (Jurkat cells)

PURPOSE: To test whether exposure to simulated GSM mobile phone signals (915 MHz, 2 W x kg(-1)) influences the concentration of calcium or calcium signalling patterns in a human lymphocyte cell line. MATERIALS AND METHODS: The radiofrequency (RF) energy was delivered via a coaxial applicator to a perfused chamber where cells adherent to a thin glass coverslip were imaged by laser scanning confocal microscopy. Cell calcium concentration, estimated from Fluo-3 fluorescence, was monitored over two 10-min periods; control followed by exposed/sham, with exposure status assigned in a blind and randomized fashion. Both continuous wave (CW) and pulsed wave (PW) RF (on both phytohaemagglutanin-activated and unactivated cells) were studied (with an equal number of sham exposures) on 100 cells per category (total 800 cells). RESULTS: No significant changes were noted for the following: regression slope of calcium fluorescence; mean calcium concentration; number of calcium 'spikes' in each 10 min; or mean height of these 'spikes'. The average frequency from Fourier spectra of these periods showed significant alteration in one category only: PW exposure of activated cells. CONCLUSIONS: There is no clear indication that RF emissions from mobile phones are associated with any changes in calcium levels or calcium signalling in lymphocytes.

334

Effects of myofascial release after high-intensity exercise: a randomized clinical trial

OBJECTIVE: The usefulness of massage as a recovery method after high-intensity exercise has yet to be established. We aimed to investigate the effects of whole-body massage on heart rate variability (HRV) and blood pressure (BP) after repeated high-intensity cycling exercise under controlled and standardized pretest conditions. METHODS: The study included 62 healthy active individuals. After baseline measurements, the subjects performed standardized warm-up exercises followed by three 30-second Wingate tests. After completing the exercise protocol, the subjects were randomly assigned to a massage (myofascial release) or placebo (sham treatment with disconnected ultrasound and magnetotherapy equipment) group for a 40-minute recovery period. Holter recording and BP measurements were taken after exercise protocol and after the intervention. RESULTS: After the exercise protocol, both groups showed a significant decrease in normal-to-normal interval, HRV index, diastolic BP (P > .001), and low-frequency domain values (P = .006). After the recovery period, HRV index (P = .42) and high-frequency (HF) (P = .94) values were similar to baseline levels in the massage group, whereas the HRV index tended (P = .05) to be lower and the HF was significantly (P < .01) lower vs baseline values in the placebo group, which also showed a tendency (P = .06) for HF to be lower than after the exercise. Likewise, diastolic BP returned to baseline levels in the massage group (P = .45) but remained lower in the placebo group (P = .02). CONCLUSION: Myofascial release massage favors the recovery of HRV and diastolic BP after high-intensity exercise (3 Wingate tests) to preexercise levels.

335

Effects of PEMF on a murine osteosarcoma cell line: drug-resistant (P-glycoprotein-positive) and non-resistant cells

After pulsed exposure of Dunn osteosarcoma cells (nonresistant cells) to Adriamycin (ADR) at increasing concentrations and single-cell cloning of surviving cells, ADR-resistant cells were obtained. These resistant cells expressed P-glycoprotein and had resistance more than 10 times that of their nonresistant parent cells. Compared to the nonresistant cells not exposed to pulsing electromagnetic fields (PEMF) in ADR-free medium, their growth rates at ADR concentrations of 0.01 and 0.02 micrograms/ml, which were below IC50, were 83.0% and 61.8%, respectively. On the other hand, in the nonresistant cells exposed to PEMF (repetition frequency, 10 Hz; rise time, 25 microsec, peak magnetic field intensity, 0.4-0.8 mT), the growth rate was 111.9% in ADR-free medium, 95.5% at an ADR concentration of 0.01 micrograms/ml, and 92.2% at an ADR concentration of 0.02 micrograms/ml. This promotion of growth by PEMF is considered to be a result of mobilization of cells in the non-proliferative period of the cell cycle due to exposure to PEMF. However, at ADR concentrations above the IC50, the growth rate tended to decrease in the cells not exposed to PEMF. This may be caused by an increase in cells sensitive to ADR resulting from mobilization of cells in the non-proliferative period to the cell cycle. The growth rate in the resistant cells exposed to PEMF was significantly lower than that in the non-exposed resistant cells at all ADR concentrations, including ADR-free culture (P

336

Effects of picotesla flux electromagnetic fields on dopaminergic transmission in Tourette's syndrome

Tourette's syndrome (TS), a chronic familial neuropsychiatric disorder of unknown etiology, is characterized clinically by the presence of motor and vocal tics that wax and wane in severity over the time and by the occurrence of a variety of neurobehavioral disorders. It is believed that the tics of TS result from increased dopamine (DA) activity caused by postsynaptic DA receptor supersensitivity. The synthesis and release of DA is regulated presynaptically by a specific class of DA D2 receptors, termed autoreceptors activation of which causes inhibition of DA synthesis and release. In experimental animals and humans administration of small doses of apomorphine, a DA D2 autoreceptor agonist, produces yawning. Recurrent episodes of yawning followed by increased motor tic activity was observed in two patients with TS during exposure to brief, extracranial applications of picotesla flux electromagnetic fields (EMFs). On the basis of these observations it is suggested that recurrent episodes of yawning in response to application of EMFs was induced by activation of presynaptic DA D2 autoreceptors while further exposure to these EMFs caused excessive stimulation of postsynaptic DA D2 receptors resulting in exacerbation of the tics. Thus, the dual effects of picotesla flux EMFs on the DA D2 autoreceptor and the postsynaptic receptor resemble the biphasic pharmacological and behavioral properties of apomorphine, a DA agonist which activates the autoreceptors in low doses while in higher doses causes stimulation of the postsynaptic receptors producing exacerbation of symptoms of TS. These findings demonstrate that picotesla flux EMFs applied extracerebrally may influence nigrostriatal DA transmission at pre- and postsynaptic DA D2 receptor sites.

337

Effects of pulse shaping in laser spectroscopy and nuclear magnetic resonance

Pulsed excitation fields are routinely used in most laser and nuclear magnetic resonance (NMR) experiments. In the NMR case, constant amplitude (rectangular) pulses have traditionally been used; in laser spectroscopy the exact pulse shape is often unknown or changes from shot to shot. This article is an overview of the effects of radio-frequency and laser pulse shapes and the instrumental requirements for pulse shaping. NMR applications to selective excitation, solvent suppression, elimination of phase roll, and reduced power dissipation are discussed, as are optical applications to soliton generation, velocity selective excitation, and quantitative population transfer.

338

Effects of pulsed and continuous wave 902 MHz mobile phone exposure on brain oscillatory activity during cognitive processing

The aim of the current double-blind studies was to partially replicate the studies by Krause et al. [2000ab, 2004] and to further investigate the possible effects of electromagnetic fields (EMF) emitted by mobile phones (MP) on the event-related desynchronisation/synchronisation (ERD/ERS) EEG (electroencephalogram) responses during cognitive processing. Two groups, both consisting of 36 male participants, were recruited. One group performed an auditory memory task and the other performed a visual working memory task in six exposure conditions: SHAM (no EMF), CW (continuous wave EMF) and PM (pulse modulated EMF) during both left- and right-side exposure, while the EEG was recorded. In line with our previous studies, we observed that the exposure to EMF had modest effects on brain oscillatory responses in the alpha frequency range ( approximately 8-12 Hz) and had no effects on the behavioural measures. The effects on the EEG were, however, varying, unsystematic and inconsistent with previous reports. We conclude that the effects of EMF on brain oscillatory responses may be subtle, variable and difficult to replicate for unknown reasons.

339

Effects of pulsed and sinusoid electromagnetic fields on human chondrocytes cultivated in a collagen matrix

Although several effects of electromagnetic fields (EMFs) on articular cartilage have been reported in recent studies, the use of EMFs to treat osteoarthritis remains a matter of debate. In an in vitro study, human chondrocytes harvested from osteoarthritic knee joints were released from their surrounding matrix and transferred in defined concentration into a 3D matrix (type-I collagen gel). The cultivation, performed under standard conditions, lasted up to 14 days. During this time, treatment groups were continuously exposed to either sinusoid or pulsed electromagnetic fields (PEMFs). The PEMFs revealed the following characteristics: maximum magnetic flux density of 2 mT, frequency of the bursts of 16.7 Hz with each burst consisting of 20 pulses. Similarly, the sinusoid EMFs also induced a maximum flux density of 2 mT with a frequency of 50 Hz. Control groups consisting of equal number of samples were not exposed to EMF. Immunohistological examinations of formalin-fixed, paraffin-embedded samples revealed positive staining for type-II collagen and proteoglycans in the immediate pericellular region with no differences between the two different treatment groups and the control groups. With increasing cultivation time, both type-II collagen and aggrecan gene expression declined, but no significant differences in gene expression were found between the treatment and control groups. In conclusion, using our in vitro setting, we were unable to detect any effects of pulsed and sinusoidal magnetic fields on human adult osteoarthritic chondrocytes.

340

Effects of pulsed electric field processing and storage on the quality and stability of single-strength orange juice

The effects of pulsed electric field (PEF) processing on microorganisms in orange juice and on the flavor and color of the juice during storage for 112 days at 4 and 22 degrees C were investigated. Single-strength orange juice was PEF processed at an electric field strength of 35 kV/cm for 59 micros and placed into sterilized glass bottles in a sanitary glove box. PEF-processed orange juice was microbiologically stable at 4 and 22 degrees C for 112 days. PEF processing resulted in significant increases in the hydrocarbons D-limonene, alpha-pinene, myrecene, and valencene (P < or = 0.05) but did not have any effect on octanal, decanal, ethyl butyrate, and linalool. The levels of hydrocarbon compounds did not change at 4 and 22 degrees C in 112 days. Octanal, decanal, ethyl butyrate, and linalool levels significantly decreased in 14 days at 4 degrees C and in 2 days at 22 degrees C. The decrease in these compounds did not have a significant effect on the sensory quality of the orange juice (P > or = 0.05). The microorganisms in PEF-processed orange juice, along with the flavor and color of the juice, remained stable at 4 degrees C for 112 days.

341

Effects of pulsed electric fields on DNA of human lymphocytes

The effects of pulsed electric fields of low frequency (50 Hz) on DNA of human lymphocytes were investigated. The influence of additional external factors, such as hydrogen peroxide (H2O2) and gamma-irradiation, as well as the repair efficiency in these lymphocytes, was also evaluated. The comet assay, a very sensitive and rapid method for detecting DNA damage at the single cells level was the method used. A significant amount of damage was observed after exposure to the electric fields, compared to the controls. After 2 h incubation at 37 degrees C, a proportion of damage was repaired. H2O2 and gamma-irradiation increased the damage to lymphocytes exposed to pulsed electric fields according to the dose used, while the amount of the repair was proportional to the damage.

342

Effects of pulsed electric fields on inactivation and metabolic activity of Lactobacillus plantarum in model beer

AIMS: Inactivation and sublethal injury of Lactobacillus plantarum at different pulsed electric field (PEF) strengths and total energy inputs were investigated to differentiate reversible and irreversible impacts on cell functionality. METHODS AND RESULTS: Lactobacillus plantarum was treated with PEF in model beer (MB) to determine critical values of field strength and energy input for cell inactivation. Below critical values, metabolic activity and membrane integrity were initially reduced without loss of viability. Above critical values, however, irreversible cell damage occurred. Presence of nisin or hop extract, during PEF treatment, resulted in an additional reduction of cell viability by 1;5 log cycles. Also, addition of the hop extract resulted in an additional two log cycles of sublethal injury. Partial reversibility of membrane damage was observed using propidium iodide (PI) uptake and staining. Inoculated MB containing hops was stored after PEF to evaluate the efficacy of such treatment for beer preservation. CONCLUSION: Cells were inactivated only above critical values of 13 kV x cm(-1) and 64 kJ x kg(-1); below these values cell damage was reversible. Storage experiments revealed that surviving cells were killed after 15 h storage in MB containing hops. SIGNIFICANCE AND IMPACT OF THE STUDY: Both reversible and irreversible cell damage due to PEF treatment was detected, depending on specific treatment conditions. The combination of PEF and hop addition is a promising nonthermal method of preservation for beer.

343

Effects of pulsed electric fields on rat liver homogenate paramagnetic species

Rat liver homogenate has been submitted to pulsed electric fields at different intensities and exposition times. Among the paramagnetic species present in the samples only the mitochondria free radical is affected by pulsation, as revealed by electron spin resonance spectroscopy. In parallel a variation in the respiratory activity of mitochondria is registered.

344

Effects of pulsed electric fields on the quality of orange juice and comparison with heat pasteurization

Effects of pulsed electric fields (PEF) at 35 kV/cm for 59 micros on the quality of orange juice were investigated and compared with those of heat pasteurization at 94.6 degrees C for 30 s. The PEF treatment prevented the growth of microorganisms at 4, 22, and 37 degrees C for 112 days and inactivated 88% of pectin methyl esterase (PME) activity. The PEF-treated orange juice retained greater amounts of vitamin C and the five representative flavor compounds than the heat-pasteurized orange juice during storage at 4 degrees C (p < 0.05). The PEF-treated orange juice had lower browning index, higher whiteness (L), and higher hue angle (theta) values than the heat-pasteurized orange juice during storage at 4 degrees C (p < 0. 05). The PEF-treated orange juice had a smaller particle size than the heat-pasteurized orange juice (p < 0.05). degrees Brix and pH values were not significantly affected by processing methods (p > 0. 05).

345

Effects of pulsed electromagnetic field (PEMF) stimulation on bone tissue like formation are dependent on the maturation stages of the osteoblasts

The effects of pulsed electromagnetic field (PEMF, 15 Hz pulse burst, 7 mT peak) stimulation on bone tissue-like formation on osteoblasts (MC3T3-E1 cell line) in different stages of maturation were assessed to determine whether the PEMF stimulatory effect on bone tissue-like formation was associated with the increase in the number of cells and/or with the enhancement of the cellular differentiation. The cellular proliferation (DNA content), differentiation (alkaline phosphatase activity), and bone tissue-like formation (area of mineralized matrix) were determined at different time points. PEMF treatment of osteoblasts in the active proliferation stage accelerated cellular proliferation, enhanced cellular differentiation, and increased bone tissue-like formation. PEMF treatment of osteoblasts in the differentiation stage enhanced cellular differentiation and increased bone tissue-like formation. PEMF treatment of osteoblasts in the mineralization stage decreased bone tissue-like formation. In conclusion, PEMF had a stimulatory effect on the osteoblasts in the early stages of culture, which increased bone tissue-like formation. This stimulatory effect was most likely associated with enhancement of the cellular differentiation, but not with the increase in the number of cells.

346

Effects of pulsed electromagnetic field on growth and differentiation of embryonal carcinoma cells

A murine embryonal carcinoma cell line (F9) was used to examine the effect of a pulsed electromagnetic field on the growth and differentiation of malignant cells. The cells can be induced to differentiate into parietal endodermal cells by treatment with retinoic acid. The pulsed electromagnetic field (1 Gauss and 10 Gauss) promoted the growth of embryonal carcinoma cells in both the presence and absence of retinoic acid. The pulsed electromagnetic field was also found to inhibit retinoic acid-induced differentiation, when the degree of differentiation was based on morphological criteria or on the production of plasminogen activator.

347

Effects of pulsed electromagnetic field stimulation on distraction osteogenesis in the rabbit tibial leg lengthening model

The purpose of this study was to determine whether exposure to pulsed electromagnetic field (PEMF) would shorten the healing time of regenerate bone in a rabbit tibial distraction model. Beginning 1 day after surgery, mid-shaft tibial osteotomies, stabilized with external fixators, were distracted 0.25 mm twice daily for 21 days and received either no exposure (sham control) or 1 hour per day exposure to low-amplitude, low-frequency PEMF. Tibiae were tested for torsional strength after 9, 16, and 23 days post-distraction. PEMF-treated tibiae were significantly stronger than shams at all three time points. By 16 days post-distraction, the PEMF group had achieved biomechanical strength essentially equivalent to intact bone. Shams did not achieve normal biomechanical strength even after 23 days post-distraction. In this tibial distraction model, short daily PEMF exposures accelerated consolidation of regenerate bone. Clinical usefulness awaits testing.

348

Effects of pulsed electromagnetic field vibration on tooth movement induced by magnetic and mechanical forces: a preliminary study

BACKGROUND: This study was designed to determine whether or not high-frequency and low-magnitude vibration affects orthodontic tooth movement caused by magnetic or/and mechanical forces. METHODS: Forty-four 7-week-old Wistar rats were randomly divided into four groups, with each group further divided into experimental and control subgroups. Neodymium-Iron-Boron (Nd-Fe-B) magnets and Sentalloy closed coil springs were placed between maxillary or mandibular first molars and incisors to activate tooth movement. The animals of experimental subgroups were exposed to the vibration induced by pulsed electromagnetic fields (PEMF) whilst the control subgroups were under normal atmosphere. The experiment lasted for 14 days and all of the animals were sacrificed for examination. The changes in the space between the molar and incisor were measured to indicate the amount of tooth movement. RESULTS: The coil springs, either with sham or active magnets, move molar much more than magnets alone, regardless of absence or presence of PEMF (p < 0.001). Under PEMF, the coil spring moved significantly more amount of tooth movement than that of coil-magnet combination (p < 0.01), as did the magnets compared to sham magnets (p < 0.019). Under a non-PEMF scenario, there was no significant difference in tooth movement between coil spring and coil-magnets combination, nor was there difference between magnets and sham magnets. CONCLUSIONS: It is suggested that the PEMF-induced vibration may enhance the effect of mechanical and magnetic forces on tooth movement.

349

Effects of pulsed electromagnetic fields on articular hyaline cartilage: review of experimental and clinical studies

Osteoarthritis (OA) is the most common disorder of the musculoskeletal system and is a consequence of mechanical and biological events that destabilize tissue homeostasis in articular joints. Controlling chondrocyte death and apoptosis, function, response to anabolic and catabolic stimuli, matrix synthesis or degradation and inflammation is the most important target of potential chondroprotective treatment, aimed to retard or stabilize the progression of OA. Although many drugs or substances have been recently introduced for the treatment of OA, the majority of them relieve pain and increase function, but do not modify the complex pathological processes that occur in these tissues. Pulsed electromagnetic fields (PEMFs) have a number of well-documented physiological effects on cells and tissues including the upregulation of gene expression of members of the transforming growth factor beta super family, the increase in glycosaminoglycan levels, and an anti-inflammatory action. Therefore, there is a strong rationale supporting the in vivo use of biophysical stimulation with PEMFs for the treatment of OA. In the present paper some recent experimental in vitro and in vivo data on the effect of PEMFs on articular cartilage were reviewed. These data strongly support the clinical use of PEMFs in OA patients.

350

Effects of pulsed electromagnetic fields on bone healing in a rabbit tibial osteotomy model

OBJECTIVE: The purpose of this study was to determine the effect of pulsed electromagnetic field (PEMF) exposure on healing tibial osteotomies in New Zealand White rabbits. DESIGN: One-millimeter Gigli saw osteotomies were stabilized by external fixation. One day after surgery, rabbits were randomly assigned to receive either no exposure (sham control) or thirty minutes or sixty minutes per day of low-frequency, low-amplitude PEMF. Radiographs were obtained weekly throughout the study. Rabbits were euthanized at fourteen, twenty-one, or twenty-eight days, and tibiae underwent either destructive torsional testing or histologic analysis. To determine the baseline torsional strength and stiffness of rabbit tibiae, eleven normal intact tibiae were tested to failure. RESULTS: Sixty-minute PEMF-treated osteotomies had significantly higher torsional strength than did sham controls at fourteen and twenty-one days postoperatively. Thirty-minute PEMF-treated osteotomies were significantly stronger than sham controls only after twenty-one days. Normal intact torsional strength was achieved by fourteen days in the sixty-minute PEMF group, by twenty-one days in the thirty-minute PEMF group, and by twenty-eight days in the sham controls. Maximum fracture callus area correlated with the time to reach normal torsional strength. CONCLUSION: In this animal model, low-frequency, low-amplitude PEMF significantly accelerated callus formation and osteotomy healing in a dose-dependent manner.

351

Effects of pulsed electromagnetic fields on cognitive processes - a pilot study on pulsed field interference with cognitive regeneration

BACKGROUND: Due to the ubiquitous use of cellular phones much has been speculated on secondary effects of electromagnetic irradiation emitted by those. Additionally, several studies have reported vegetative alterations as well as effects on the neuronal and molecular levels in humans. Here, using a psycho-physiological test paradigm, we examined effects of exposure to pulsed electromagnetic fields on cognitive performance. MATERIALS AND METHODS: In 11 volunteers, we tested cognitive processing under field exposure (GSM standard) and under field-free conditions. To examine the hypothesized effect of pulsed fields, we applied an auditory discrimination task and determined the participant's current 'Order Threshold' value. Following a first test cycle, the volunteers had to relax for 50 min while being, or not, exposed to pulsed electromagnetic fields. Subsequently, the test was repeated. Data acquired before and after the resting phase were compared from both experimental conditions. RESULTS: We found that nine of the 11 test participants (81.8%) showed worse results in their auditory discrimination performance upon field exposure as compared with control conditions. Group data comparison revealed a statistical significance of P = 0.0105. CONCLUSION: We could show that the participants' cognitive performance was impaired after exposure to pulsed electromagnetic fields. With regard to this finding, we recommend that the use of cellular phones should be restricted generally and in particular in respect of physical hazard of high-risk groups, e.g. elderly, children and ill people.

352

Effects of pulsed electromagnetic fields on human articular chondrocyte proliferation

Low-energy, low-frequency pulsed electromagnetic fields (PEMFs) can induce cell proliferation in several cell culture models. In this work we analysed the proliferative response of human articular chondrocytes, cultured in medium containing 10% FBS, following prolonged exposure to PEMFs (75 Hz, 2.3 mT), currently used in the treatment of some orthopaedic pathologies. In particular, we investigated the dependence of the proliferative effects on the cell density, the availability of growth factors and the exposure lengths. We observed that PEMFs can induce cell proliferation of low density chondrocyte cultures for a long time (6 days), when fresh serum is added again in the culture medium. In the same conditions, in high density cultures, the PEMF-induced increase in cell proliferation was observed only in the first three days of exposure. The data presented in this study show that the availability of growth factors and the environmental constrictions strongly condition the cellular proliferative response to PEMFs.

353

Effects of pulsed electromagnetic fields on human chondrocytes: an in vitro study

(3)H-thymidine incorporation was studied in cultured human nasal and articular chondrocytes exposed to low-energy, low-frequency pulsed electromagnetic fields (PEMFs) (75 Hz, 2.3 mT). The reverse transcriptase polymerase chain reaction (RT-PCR) analysis shows that human secondary chondrocytes derived from both nasal and articular cartilage express collagen type II mRNA, which is a specific marker of the chondrocyte phenotype. In a preliminary series of experiments, cells were exposed to PEMF for different time periods ranging from 6 to 30 hours (time-course), in medium supplemented with 10% or 0.5% fetal calf serum (FCS) and in serum-free medium. The ratios between the (3)H-thymidine incorporation in PEMFs and control cultures show an increase of the cell proliferation in cultures exposed to PEMFs when serum is present in the culture medium, whereas no effect was observed in serum-free conditions. The increase in DNA synthesis, induced by PEMFs, was then evaluated only at the times of maximum induction and the results were analyzed by the three-factor analysis of variance (ANOVA). The data presented in this study show that even if (3)H-thymidine incorporation is higher in nasal than in articular chondrocytes, PEMF induce an increase in the proliferation of both cell types. Moreover, the concentration of FCS in the culture medium greatly influences the proliferative response of human chondrocytes to the PEMF exposure. Though normal human osteoblast cells increase their proliferation when exposed to PEMFs if only 10% FCS is present in the medium, human chondrocytes are able to increase their cell proliferation when exposed to PEMFs in the presence of both 0.5% and 10% of FCS in the medium. The results obtained may help to explain the basic mechanisms of PEMF stimulation of fracture healing.

354

Effects of pulsed electromagnetic fields on Na+ fluxes across stripped rabbit colon epithelium

The effect of pulsed electromagnetic fields on the electrical potential and two-way flux of Na+ across the epithelium of the rabbit colon in vitro was investigated. In control experiments the transepithelial mucosal-to-serosal and serosal-to-mucosal fluxes (Jm----s and Js----m) were constant over the experimental period. When the epithelium was at right angles to the applied electromagnetic field, the Jm----s flux of Na+ was reduced, whereas Js----m was enhanced. When the epithelium was rotated 180 degrees, Jm----s was enhanced, whereas Js----m was reduced. When the epithelium was mounted parallel to the magnetic field, both Jm----s and Js----m of Na+ were increased, the latter continuing to increase after the field was turned off. When the tissue was rotated 180 degrees, the same enhanced flux was observed, but now the Jm----s flux showed the greatest increase, which again occurred in the period after the field was turned off. The rate of decrease of transepithelial potential difference in all orientations was less than the control. Also, the conductance increased in orientations 2-4 and decreased in orientation 1 after the field had been applied. This suggests that pulsed electromagnetic fields can have a direct effect on the movement of Na+ across tissue and transepithelial potentials. The mechanism may depend on several factors, such as induced changes in certain ion pumps, the membrane potential, and the surface charge of cell wall proteins.

355

Effects of pulsed electromagnetic fields on patients' recovery after arthroscopic surgery: prospective, randomized and double-blind study

Severe joint inflammation following trauma, arthroscopic surgery or infection can damage articular cartilage, thus every effort should be made to protect cartilage from the catabolic effects of pro-inflammatory cytokines and stimulate cartilage anabolic activities. Previous pre-clinical studies have shown that pulsed electromagnetic fields (PEMFs) can protect articular cartilage from the catabolic effects of pro-inflammatory cytokines, and prevent its degeneration, finally resulting in chondroprotection. These findings provide the rational to support the study of the effect of PEMFs in humans after arthroscopic surgery. The purpose of this pilot, randomized, prospective and double-blind study was to evaluate the effects of PEMFs in patients undergoing arthroscopic treatment of knee cartilage. Patients with knee pain were recruited and treated by arthroscopy with chondroabrasion and/or perforations and/or radiofrequencies. They were randomized into two groups: a control group (magnetic field at 0.05 mT) and an active group (magnetic field of 1.5 mT). All patients were instructed to use PEMFs for 90 days, 6 h per day. The patients were evaluated by the Knee injury and Osteoarthritis Outcome Score (KOOS) test before arthroscopy, and after 45 and 90 days. The use of non-steroidal anti-inflammatory drugs (NSAIDs) to control pain was also recorded. Patients were interviewed for the long-term outcome 3 years after arthroscopic surgery. Thirty-one patients completed the treatment. KOOS values at 45 and 90 days were higher in the active group and the difference was significant at 90 days (P < 0.05). The percentage of patients who used NSAIDs was 26% in the active group and 75% in the control group (P = 0.015). At 3 years follow-up, the number of patients who completely recovered was higher in the active group compared to the control group (P < 0.05). Treatment with I-ONE aided patient recovery after arthroscopic surgery, reduced the use of NSAIDs, and also had a positive long-term effect.

356

Effects of pulsed electromagnetic fields on postoperative pain: a double-blind randomized pilot study in breast augmentation patients

BACKGROUND: Postoperative pain may be experienced after breast augmentation surgery despite advances in surgical techniques which minimize trauma. The use of pharmacologic analgesics and narcotics may have undesirable side effects that can add to patient morbidity. This study reports the use of a portable and disposable noninvasive pulsed electromagnetic field (PEMF) device in a double-blind, randomized, placebo-controlled pilot study. This study was undertaken to determine if PEMF could provide pain control after breast augmentation. METHODS: Forty-two healthy females undergoing breast augmentation for aesthetic reasons entered the study. They were separated into three cohorts, one group (n = 14) received bilateral PEMF treatment, the second group (n = 14) received bilateral sham devices, and in the third group (n = 14) one of the breasts had an active device and the other a sham device. A total of 80 breasts were available for final analysis. Postoperative pain data were obtained using a visual analog scale (VAS) and pain recordings were obtained twice daily through postoperative day (POD) 7. Postoperative analgesic medication use was also followed. RESULTS: VAS data showed that pain had decreased in the active cohort by nearly a factor of three times that for the sham cohort by POD 3 (p < 0.001), and persisted at this level to POD 7. Patient use of postoperative pain medication correspondingly also decreased nearly three times faster in the active versus the sham cohorts by POD 3 (p < 0.001). CONCLUSION: Pulsed electromagnetic field therapy, adjunctive to standard of care, can provide pain control with a noninvasive modality and reduce morbidity due to pain medication after breast augmentation surgery.

357

Effects of pulsed electromagnetic fields on rat skin metabolism

In an attempt to approach the mechanism of action of pulsed electromagnetic fields (PEMF) on biological systems, the effects on protein synthesizing activity and on membrane transport have been examined in rat skin. PEMF characterized by specific physical parameters stimulate the incorporation of L-[U-14C]isoleucine into the proteins of rat skin as well as the alpha-amino[1-14C]isobutyric acid uptake during incubation in buffer medium with extracellular electrolyte composition. Analogous incubation experiments carried out in an intracellular medium results in an inhibitory effect of PEMF on both biological functions. Addition of 10(-3) M ouabain to the incubation medium, partially blocking the Na+/K+-ATPase pump mechanism, apart from reducing amino acid transport, results in an overall disappearance of any stimulatory effects by PEMF. PEMF applied to the skin in the presence of 10(-3) M 2,4-dinitrophenol uncoupling the oxidative phosphorylation in the mitochondria and seriously restricting protein synthesis, still provides a limited stimulatory effect on protein synthesizing activity and on membrane transport. The effects of PEMF may well be understood by an increased availability of precursor elements controlled at the cell membrane level. Indeed the observed effects may even be simulated outside electromagnetic fields by modifications in the electrolyte composition of the incubation medium.

358

Effects of pulsed electromagnetic fields on Steinberg ratings of femoral head osteonecrosis

Between 1979 and 1985, 95 patients with femoral head osteonecrosis met the protocol for treatment of 118 hips with selected pulsed electromagnetic fields (PEMFs). Etiologies included trauma (17), alcohol (9), steroid use (46), sickle cell disease (2), and idiopathy (44). The average age was 38 years, and the average follow-up period since the onset of symptoms was 5.3 years. PEMF treatment had been instituted an average of 4.1 years earlier. By the Steinberg quantitative staging method of roentgenographic analysis, none of the 15 hips in Stages 0-III showed progression, and grading improved in nine of 15. Eighteen of 79 hips (23%) with Stage IV lesions progressed and none improved. In the Stage V category, one of 21 hips (5%) worsened and none improved. Three Stage VI lesions were unchanged. The overall rate of quantified progression for the 118 hips, 87% of which had collapse present when entering the program, was 16%. This value represents a reversal of the percentage of progression reported recently by other investigators using conservative and selected surgical methods. PEMF patients also have experienced long-term improvements in symptoms and signs, together with a reduction in the need for early joint arthroplasty.

360

Effects of pulsed extremely-low-frequency magnetic fields on skin wounds in the rat

Rats with skin-wounds surgically created on their backs were exposed immediately after surgery and every 12 h thereafter to pulsed, extremely-low-frequency magnetic fields. The shape of the pulse was a positive triangle (50 Hz, 8 mT peak). The rate of healing of skin wounds was evaluated macroscopically and by light and electron microscopy at 6, 12, 21, and 42 days after the operation. A significant increase in the rate of wound contraction was found in rats treated with magnetic fields. Forty-two days after surgery all treated animals show fully closed wounds, while control rats at the same time intervals still lacked a final 6% of the wound surface to be covered. Treated rats showed earlier cellular organization, collagen formation and maturation, and a very early appearance of newly formed vascular network.

361

Effects of pulsed high-frequency electromagnetic fields on human sleep

In the present study we investigated the influence of pulsed high-frequency electromagnetic fields of digital mobile radio telephones on sleep in healthy humans. Besides a hypnotic effect with shortening of sleep onset latency, a REM suppressive effect with reduction of duration and percentage of REM sleep was found. Moreover, spectral analysis revealed qualitative alterations of the EEG signal during REM sleep with an increased spectral power density. Knowing the relevance of REM sleep for adequate information processing in the brain, especially concerning mnestic functions and learning processes, the results emphasize the necessity to carry out further investigations on the interaction of this type of electromagnetic fields and the human organism.

362

Effects of pulsed high-frequency electromagnetic fields on the neuroendocrine system

The influence of pulsed high-frequency electromagnetic fields emitted from a circularly polarized antenna on the neuroendocrine system in healthy humans was investigated (900 MHz electromagnetic field, pulsed with 217 Hz, average power density 0.02 mW/cm2). Nocturnal hormone profiles of growth hormone (GH), cortisol, luteinizing hormone (LH) and melatonin were determined under polysomnographic control. An alteration in the hypothalamo-pituitary-adrenal axis activity was found with a slight, transient elevation in the cortisol serum level immediately after onset of field exposure which persisted for 1 h. For GH, LH and melatonin, no significant effects were found under exposure to the field compared to the placebo condition, regarding both total hormone production during the entire night and dynamic characteristics of the secretion pattern. Also the evaluation of the sleep EEG data revealed no significant alterations under field exposure, although there was a trend to an REM suppressive effect. The results indicate that weak high-frequency electromagnetic fields have no effects on nocturnal hormone secretion except for a slight elevation in cortisol production which is transient, pointing to an adaptation of the organism to the stimulus.

363

Effects of pulsed low frequency electromagnetic fields on water using photoluminescence spectroscopy: role of bubble/water interface

The effects of a pulsed low frequency electromagnetic field were investigated on photoluminescence of well characterized water and prepared under controlled conditions (container, atmospheric, electromagnetic, and acoustic environments). When reference water samples were excited at 260 nm, two wide emission bands centered at 345 nm (3.6 eV) and 425 nm (2.9 eV) were observed. By contrast under 310 nm excitation, only one band appeared at 425 nm. Interestingly, electromagnetic treatment (EMT) induced, at both excitation wavelengths, a decrease (around 70%) in the 425 nm band relative photoluminescence intensity. However, no difference between reference and treated sample was observed in the 345 nm band. Other experiments, performed on outgassed samples (reference and treated), show that the emission bands (position, shape, intensity) under excitation at 260 nm and 310 nm were similar and close to the corresponding bands of the treated nonoutgassed samples. Similar effects were observed on photoluminescence excitation of water samples. Two excitation bands monitored at 425 nm were observed at 272 nm and 330 nm. After EMT and/or outgassing, a decrease (>60%) was observed in the intensity of these two bands. Altogether, these results indicate that electromagnetic treatment and/or outgassing decrease in a similar fashion the photoluminescence intensity in water samples. They also suggest that this effect is most likely indirectly attributed to the presence of gas bubbles in water. The possible role of hydrated ionic shell around the bubbles in the observed extraluminescence is discussed.

364

Effects of pulsed magnetic energy on a microsurgically transferred vessel

This article reports the findings of a study that attempted to elucidate whether pulsed magnetic energy stimulates neovascularization in vivo, using a microsurgically created arterial loop model in a prospective randomized trial of 108 rats (n = 12/group). Pulsed magnetic energies of 0.1 and 2.0 gauss were applied immediately postoperatively and for 4, 8, and 12 weeks, respectively, with a statistically significant increase in neovascularization among the treated animals compared with control rats. The study provides a starting point for future study and evaluation of the stimulation of angiogenesis with the use of pulsed magnetic energy and suggests a possible use of this modality to increase the quality of revascularized tissue.

365

Effects of pulsed magnetic fields in the therapy of osteoporosis induced by ovariectomy in the rat

This paper presents preliminary results on the effects of pulsed electromagnetic fields (EMF) in the therapy of post menopausal osteoporosis induced by ovariectomy in female rats aged ten months. In particular, the effects of the intensity of pulsed EMF applied at constant frequency has been studied. Magnetic fields pulsed at 50 Hz were used having a positive sinusoidal wave form with a maximum intensity of 30 and 70 Gauss. Treatment lasting one hour per day for 4 months showed that the pulsed EMF with 30 Gauss of maximum intensity are able to slow down the bone mass loss, keeping it within some 10%; with pulsed EMF with 70 Gauss of maximum intensity, instead, no significant bone mass loss was observed.

366

Effects of pulsed magnetic fields on neurite outgrowth from chick embryo dorsal root ganglia

We have previously shown that neurite outgrowth from 6-day chick embryo dorsal root ganglia (DRG) in vitro was stimulated when nerve growth factor (NGF) and pulsed magnetic fields (PMF) are used in combination. 392 DRGs were studied in a field excited by a commercial PMF generator. We have now analyzed an additional 416 DRGs exposed to very similar PMF's produced by an arbitrary wavefrom generator and power amplifier. We reproduced our previous findings that combination of NGF and bursts of asymmetric, 220 microsecond-wide, 4.0 mT-peak pulses induced significantly (p < 0.05) greater outgrowth than NGF alone, that fields without NGF do not significantly alter outgrowth, and that, unlike NGF alone, 4.0 mT fields and NGF can induce asymmetric outgrowth. The asymmetry does not seem to have a preferred orientation with respect to the induced electric field. Analysis of the data for the entire 808 DRGs confirms these findings. Importantly, we find similar results for pulse bursts repeated at 15 or 25 Hz.

367

Effects of pulsed magnetic fields on the developing mouse embryo

The influence of a pulsed magnetic field (PMF; sawtooth with 45-microseconds linear rise time and 5-microseconds decay time, peak strength of 15 microT, and frequency 20000 pps) [corrected] on the embryogenesis of CBA/S mice was investigated in five experiments based on a total of 707 exposed and 543 unexposed primigravidas. Sham and PMF exposures began on day 1 of gestation (experiments 1 and 2), on day 2 (experiment 3), on day 5 (experiment 4), and on day 7 (experiment 5); all exposures continued until day 19 post conception (p.c.), when they were terminated, at which time the following variables were measured: number of implants; number of placental resorptions; number of living fetuses; number of dead fetuses; number of malformations in living and dead fetuses; and length and body mass of living fetuses. Control dams were sham-exposed concurrently with corresponding, PMF-exposed dams. With the exception of experiment 5, in which exposure to PMF started on day 7 p.c., all groups of exposed mice had significantly more placental resorptions when compared with concurrent controls. The increased resorption rate was not reflected in a reduction in litter size or in the number of litters. A significant increase in malformed fetuses was not seen in any of the exposed groups, or when groups were pooled. Only in experiment 1 was the number of dead fetuses affected by exposure to PMF. The effect of PMF on the implantation rate was not significant. Body mass and length of exposed fetuses were significantly reduced only when the PMF treatment began on day 7 p.c.(ABSTRACT TRUNCATED AT 250 WORDS)

368

Effects of pulsed magnetic stimulation of GFAP levels in cultured astrocytes

The present study evaluates the physiological effects of magnetic stimulation on astrocyte cultures. Cell cultures were exposed to pulsed magnetic stimulation (10 Hz, 10 sec) at the following levels: 0.10 tesla (T; Group A); 0.21 T (Group B); 0.42 T (Group C); and 0.63 T (Group D). Glial fibrillary acidic protein (GFAP) levels from immunoblots, total protein concentrations, and cellular morphology were analyzed at 0, 1, 3, 5, 7, 13, and 20 days poststimulation. Significantly higher GFAP levels were observed in Group D at day 3 (P = 0.0114). The change was transient as the GFAP levels quickly returned to control levels by day 5. No other significant changes in GFAP levels were observed. In comparison to control protein levels at day 0, concentrations from Groups B, C, and D were significantly lower (P < 0.006), whereas at day 3, Groups C and D were significantly higher (P < 0.02). Differences in astrocyte morphology due to magnetic stimulation were not observed. This study demonstrated that high intensity magnetic stimulation for only 10 sec induced a transient biological response.

369

Effects of pulsed magnetic stimulation on tumor development and immune functions in mice

We investigated the effects of pulsed magnetic stimulation on tumor development processes and immune functions in mice. A circular coil (inner diameter = 15 mm, outer diameter = 75 mm) was used in the experiments. Stimulus conditions were pulse width = 238 micros, peak magnetic field = 0.25 T (at the center of the coil), frequency = 25 pulses/s, 1,000 pulses/sample/day and magnetically induced eddy currents in mice = 0.79-1.54 A/m(2). In an animal study, B16-BL6 melanoma model mice were exposed to the pulsed magnetic stimulation for 16 days from the day of injection of cancer cells. A tumor growth study revealed a significant tumor weight decrease in the stimulated group (54% of the sham group). In a cellular study, B16-BL6 cells were also exposed to the magnetic field (1,000 pulses/sample, and eddy currents at the bottom of the dish = 2.36-2.90 A/m(2)); however, the magnetically induced eddy currents had no effect on cell viabilities. Cytokine production in mouse spleens was measured to analyze the immunomodulatory effect after the pulsed magnetic stimulation. tumor necrosis factor (TNF-alpha) production in mouse spleens was significantly activated after the exposure of the stimulus condition described above. These results showed the first evidence of the anti-tumor effect and immunomodulatory effects brought about by the application of repetitive magnetic stimulation and also suggested the possible relationship between anti-tumor effects and the increase of TNF-alpha levels caused by pulsed magnetic stimulation.

370

Effects of repetitive transcranial magnetic stimulation on behavioral and neurochemical changes in rats during an elevated plus-maze test

In transcranial magnetic stimulation (TMS) the regional electrical activity in the brain is influenced by a pulsed magnetic field. The rapidly changed magnetic field produces electrical currents that activate neurons. Repetitive TMS (rTMS) treatment can cause functional changes in the cortex. The present study clarified the effects of rTMS treatment on behavioral changes in rats, focusing on anxiety by using an elevated plus-maze (plus-maze) test. The effects of rTMS treatment on neurochemical changes during the plus-maze test were investigated by determining the extracellular levels of serotonin (5-HT) and dopamine (DA) in the prefrontal cortex by using in vivo microdialysis. Each rat received rTMS of the frontal brain for 3 days, during which 125 stimuli from five trains in a day were applied at 25 Hz for 1 s with 2-min intervals between trains. Three-day series of (chronic) rTMS treatment caused significant increases in the time spent in open arms and the number of entries into open arms of the plus-maze compared with non-treated and sham-treated rats, which were not observed in 1-day series of (acute) rTMS treatment. Chronic rTMS treatment suppressed the increases in 5-HT levels induced by the plus-maze test, but did not influence the elicited DA levels. These data suggest that chronic rTMS treatment of the frontal brain has anxiolytic effects in rats, which are related to the 5-HTergic neuronal system.

371

Effects of short- and long-term pulsed radiofrequency electromagnetic fields on night sleep and cognitive functions in healthy subjects

There has been wide public discussion on whether the electromagnetic fields of mobile telephones and their base stations affect human sleep or cognitive functioning. As there is evidence for learning and memory-consolidating effects of sleep and particularly of REM sleep, disturbance of sleep by radiofrequency electromagnetic fields might also impair cognitive functions. Previously realized sleep studies yielded inconsistent results regarding short-term exposure. Moreover, data are lacking on the effect that short- and long-term exposure might have on sleep as well as on cognitive functions. Therefore, 10 healthy young male subjects were included and nocturnal sleep was recorded during eight consecutive nights. In the second, third, and last night, we investigated polysomnographic night sleep and cognitive functions. After the adaptation and baseline nights, the participants were exposed to a defined radiofrequency electromagnetic field during the following six nights. We analyzed polysomnographic night sleep according to Rechtschaffen and Kales [1968, Manual of Standardized Terminology, Techniques and Scoring System for Sleep of Human Subjects] as well as by power spectra and correlation dimension. Cognitive functions were investigated by an array of neuropsychological tests. Data analysis was done by comparing the baseline night with the first and last exposure night and the first two sleep cycles of the respective nights. We did not find significant effects, either on conventional sleep parameters or on power spectra and correlation dimension, nor were there any significant effects on cognitive functions. With our results, we are unable to reveal either short-term or cumulative long-term effects of radiofrequency electromagnetic fields on night sleep and cognitive functions in healthy young male subjects.

372

Effects of smoking and maturation on long-term maintenance of lumbar spinal fusion success

This is a follow-up study of a multicenter, randomized, placebo-controlled clinical trial conducted in accordance with the condition for Food and Drug Administration approval for pulsed electromagnetic fields. The purpose of this study was to evaluate the long-term efficacy and safety of pulsed electromagnetic fields for spinal fusion. An earlier clinical trial study was conducted to evaluate the efficacy of Pulsed Electromagnetic Fields to enhance fusion success at one year follow-up. In the original study, 195 patients undergoing interbody fusion were enrolled. Of the 195 patients, 98 were in the active group and 97 were in the placebo group. Study results showed a 92% successful fusion rate in the active group compared to 68% in the placebo group. For this long-term follow-up study, all patients who had healed in the original study were recalled for a follow-up radiograph. Radiographs were assessed by the attending surgeon for fusion assessment, when possible. The results of this long-term follow-up study showed that there was a reduction in maintenance of the fusion over time by 25%, but that the reduction was unrelated to treatment group and correlated statistically with whether the patient was a smoker.

373

Effects of static magnetic and pulsed electromagnetic fields on bone healing

The purpose of the present study was to evaluate the healing pattern of an experimentally induced osteotomy in Hartley guinea pigs in the presence of static magnetic and pulsed electromagnetic fields. The sample consisted of 30 Hartley guinea pigs 2 weeks of age divided into 3 groups: pulsed electromagnetic, static magnetic, and control. An osteotomy was performed in the mandibular postgonial area in all groups under general anesthesia. During the experimental period of 9 days, the animals were kept in experiment cages 8 hours per day, the first two groups being in the presence of pulsed electromagnetic and static magnetic field, respectively. Based on histologic results, both static and pulsed electromagnetic fields seemed to accelerate the rate of bone repair when compared to the control group. The osteotomy sites in the control animals consisted of connective tissue, while new bone had filled the osteotomy areas in both magnetic field groups.

374

Effects of static magnetic field and pulsed electromagnetic field on viability of human chondrocytes in vitro

Effects of electromagnetic fields (EMFs) on human cell lines were described in numerous studies, but still many questions remain unanswered. Our experiment was designed with the aim of studying the effects of EMFs on the metabolic activity of chondrocytes in vitro. Human chondrocyte in vitro cultures, cultured in medium supplemented with 20 % fetal calf serum, were exposed to static magnetic field (SMF) (intensity of 0.6 T) and pulsed electromagnetic fields (PEMF) (21.2 MHz period of 15 ms, burst duration of 2 ms, amplification 3 dBm (0.1 V) and maximum output of 250 W) continually for 72 h. After the exposure, viability was determined using the MTT test and compared with a non-exposed control culture. As compared to the control sample the exposure to SMF resulted in a statistically significant increase (p 0.001) in viability. However, the increase of viability after PEMF exposure was not significant. This could be due to the frequency dependent effect on human cells. The experiments demonstrated that magnetic fields, using the above parameters, have a positive effect on the viability of human chondrocytes cultured in vitro.

375

Effects of static magnetic fields on bone formation in rat osteoblast cultures

Although the promotional effects on osteoblasts of pulsed electromagnetic fields have been well-demonstrated, the effects of static magnetic fields (SMF) remain unclear; nevertheless, magnets have been clinically used as a 'force source' in various orthodontic treatments. We undertook the present investigation to study the effects of SMF on osteoblastic differentiation, proliferation, and bone nodule formation using a rat calvaria cell culture. During a 20-day culture, the values of the total area and the number and average size of bone nodules showed high levels in the presence of SMF. In the matrix development and mineralization stages, the calcium content in the matrix and two markers of osteoblastic phenotype (alkaline phosphatase and osteocalcin) also showed a significant increase. Accordingly, these findings suggest that SMF stimulates bone formation by promoting osteoblastic differentiation and/or activation.

376

Effects of steep pulsed electric fields (SPEF) on mitochondrial transmembrane potential of human liver cancer cell

Mitochondrial plays an important role in apoptosis, and measuring the change of mitochondrial transmembrane potential (delta psi m) is a useful method for apoptosis. Exposing human liver cancer cell SMMC-7721 dyed with Rhodamine 123 to steep pulsed electric fields (SPEF), this paper observed the real-time change of delta psi m using laser scanning confocal microscope (LSCM) to study the apoptosis effect of SPEF. The experiment results showed that delta psi m decreased gradually in process of exposing to SPEF, SPEF with higher voltage (600V) and shorter width (100ns) could cause a quicker decrease than SPEF with lower voltage (200V) and longer width (1.3mus). Such phenomenon kept up even after canceling SPEF, this may lead to collapse of delta psi m and induce apoptosis with tremendous possibilities. The experiment results of flow cytometry (SMMC-7721 dyed with Annexin V-FITC) approved that SPEF could induce apoptosis markedly (P<0.01); SPEF with lower voltage (200V) and longer width (1.3mus) could induce apoptosis more effectively (P<0.01) than SPEF with higher voltage (600V) and shorter width (100ns). These experiment results supply possible mechanism and parameter selection basis for tumor treatment using SPEF.

377

Effects of strong pulsed magnetic fields on the cardiac activity of an open chest dog

The heart of an open chest dog was stimulated by strong magnetic fields which were damped sinusoidal pulses with the one-cycle period of 1.47 ms. Stimulation effects were detected by electrocardiograph (ECG) and arterial blood pressure as a function of the strength of the field, the triggering point in the cardiac cycle, and the position of a stimulating coil. The threshold for arrhythmias was a minimum for the stimuli triggered at the apex of the T wave and on the P wave in the ECG. Premature ventricular and premature atrial contractions occurred according to whether the coil was placed over the ventricles or the atria. Ventricular defibrillation can not be attained by the magnetic stimulus with the flux density of 9.2 T which was the maximum field used.

378

Effects of the electromagnetic field, 60 Hz, 3 microT, on the hormonal and metabolic regulation of undernourished pregnant rats

Epidemiological studies have implicated maternal protein-calorie deficiency as an important public health problem in developing countries. Over the last decades, a remarkable diffusion of electricity and an increased level of the electromagnetic field (EMF) in the environment have characterized modern societies. Therefore, researchers are concerned with the biological effects of 50-60 Hz, EMF. The aim of this paper is to show the effects of EMF of 60 Hz, 3 muT, exposure for two hours per day in the regulation of the hormonal and metabolic concentrations in pregnant rats, which were fed by Regional Basic Diet (RBD) during their pregnancy as compared with pregnant rats fed a standard diet. Pregnant rats exposed to EMF of 60 Hz, 3 muT, over the pregnancy and fed with RBD presented an increase in glucose release when compared with the Group subjected only to the RBD ration. Rats fed RBD presented a decrease in their insulin and cortisol serum levels when compared with the Group fed with casein. The T3 and T4 concentrations presented the greatest variation among the Groups. The relation T4:T3 was much exaggerated in the Group subjected to RDB and exposed to EMF when compared to the others. In conclusion, the group subjected to the association of EMF and undernutrition suffered a decrease in its serum concentration of T4 and T3 when compared to the well-nourished group and the relationship T4:T3 in the former group was almost eighteen-fold the later one.

379

Effects of thirty minutes mobile phone use on the human sensory cortex

OBJECTIVE: To investigate whether the pulsed high-frequency electromagnetic field (pulsed EMF) emitted by a mobile phone for 30 min has short-term effects on human somatosensory evoked potentials (SEPs). METHODS: We studied somatosensory evoked potentials (SEPs) in 12 normal volunteers before and after exposure to the electromagnetic field emitted by a mobile phone for 30 min compared with sham exposure. In 7 out of the subjects we also measured the recovery function of the SEP. RESULTS: Neither SEPs nor their recovery function was affected by exposure to pulsed EMF emitted by a mobile phone or sham phone use. CONCLUSIONS: As far as the present methods are concerned, 30 min mobile phone use has no short-term effects on the human sensory cortex. SIGNIFICANCE: This is the first study of SEPs after electromagnetic exposure by the mobile phone. Our results support the safety of the mobile phone.

380

Effects of thirty-minute mobile phone exposure on saccades

OBJECTIVE: To investigate whether exposure to pulsed high-frequency electromagnetic field (pulsed EMF) emitted by a mobile phone has short-term effects on saccade performances. METHODS: A double blind, counterbalanced crossover design was employed. In 10 normal subjects, we studied the performance of visually guided saccade (VGS), gap saccade (GAP), and memory guided saccade (MGS) tasks before and after exposure to EMF emitted by a mobile phone for thirty minutes or sham exposure. We also implemented a hand reaction time (RT) task in response to a visual signal. RESULTS: With the exception of VGS and MGS latencies, the parameters of VGS, GAP and MGS tasks were unchanged before and after real or sham EMF exposure. In addition, the latencies of VGS and MGS did not change differently after real and sham exposure. The hand RT shortened with the repetition of trials, but again this trend was of similar magnitude for real and sham exposures. CONCLUSIONS: Thirty minutes of mobile phone exposure has no significant short-term effect on saccade performances. SIGNIFICANCE: This is the first study to investigate saccade performance in relation to mobile phone exposure. No significant effect of mobile phone use was demonstrated on the performance of various saccade tasks, suggesting that the cortical processing for saccades and attention is not affected by exposure to EMF emitted by a mobile phone.

381

Effects of thirty-minute mobile phone use on visuo-motor reaction time

OBJECTIVE: To investigate whether exposure to pulsed high-frequency electromagnetic field (pulsed EMF) emitted by a mobile phone has short-term effects on the visuo-motor choice reaction time (RT) and movement time (MT). METHODS: A double blind, counterbalanced crossover design was employed. In 16 normal subjects, we studied the performance of a visuo-motor precued choice reaction time task (PCRT) before and after exposure to EMF emitted by a mobile phone for 30 minutes or sham exposure. RESULTS: The RTs and MTs under different conditions of precue information were not affected by exposure to pulsed EMF emitted by a mobile phone or by sham phone use. CONCLUSIONS: Thirty minutes of mobile phone use has no significant short-term effect on the cortical visuo-motor processing as studied by the present PCRT task. SIGNIFICANCE: This is the first study to investigate visuo-motor behavior in relation to mobile phone exposure. No significant effect of mobile phone use was demonstrated on the performance of the visuo-motor reaction time task.

382

Effects of time-varying uniform magnetic fields on natural killer cell activity and antibody response in mice

Natural Killer cell activity and antibody response were studied in Balb/c mice which were exposed in vivo to uniform pulsed magnetic fields (square-wave, 0.8 Hz, 120 mT maximum field strength, 0.1 s rise-time) for 5 days, 10 h/day. No effects were found in antibody response to sheep red blood cell (SRBC) immunization as assayed by counting the plaque-forming cells (PFC) in the spleens of animals on the sixth day. Following 5-day exposures, the activity of Natural Killer (NK) cells was measured in vitro by challenge with YAC-1 cells, in experiments in which mice were not immunized. An increase of NK cytotoxic activity due to exposure was found which depended on the age of the mice (effect observed above 12 weeks) and on the strength of the applied field (effect observed above 30 mT).

383

Effects of visible light on the skin

Electromagnetic radiation has vast and diverse effects on human skin. Although photobiologic studies of sunlight date back to Sir Isaac Newton in 1671, most available studies focus on the UV radiation part of the spectrum. The effects of visible light and infrared radiation have not been, until recently, clearly elucidated. The goal of this review is to highlight the effects of visible light on the skin. As a result of advances in the understanding of skin optics, and comprehensive studies regarding the absorption spectrum of endogenous and exogenous skin chromophores, various biologic effects have been shown to be exerted by visible light radiation including erythema, pigmentation, thermal damage and free radical production. It has also been shown that visible light can induce indirect DNA damage through the generation of reactive oxygen species. Furthermore, a number of photodermatoses have an action spectrum in the visible light range, even though most of the currently available sunscreens offer, if any, weak protection against visible light. Conversely, because of its cutaneous biologic effects, visible light is used for the treatment of a variety of skin diseases and esthetic conditions in the form of lasers, intense pulsed light and photodynamic therapy.

384

Effects of weak, low-frequency pulsed electromagnetic fields (BEMER type) on gene expression of human mesenchymal stem cells and chondrocytes: an in vitro study

In vitro effects of electromagnetic fields appear to be related to the type of electromagnetic field applied. Previously, we showed that human osteoblasts display effects of BEMER type electromagnetic field (BTEMF) on gene regulation. Here, we analyze effects of BTEMF on gene expression in human mesenchymal stem cells and chondrocytes. Primary mesenchymal stem cells from bone marrow and the chondrocyte cell line C28I2 were stimulated 5 times at 12-h intervals for 8 min each with BTEMF. RNA from treated and control cells was analyzed for gene expression using the affymetrix chip HG-U133A. A limited number of regulated gene products from both cell types mainly affect cell metabolism and cell matrix structure. There was no increased expression of cancer-related genes. RT-PCR analysis of selected transcripts partly confirmed array data. Results indicate that BTEMF in human mesenchymal stem cells and chondrocytes provide the first indications to understanding therapeutic effects achieved with BTEMF stimulation.

385

Effects of whole body exposure to extremely low frequency electromagnetic fields (ELF-EMF) on serum and liver lipid levels, in the rat.

BACKGROUND: [corrected] The effects of extremely low-frequency electromagnetic fields (ELF-EMF) on the blood serum and liver lipid concentrations of male Wistar rats were assessed. METHODS: Animals were exposed to a single stimulation (2 h) of ELF-EMF (60 Hz, 2.4 mT) or sham-stimulated and thereafter sacrificed at different times (24, 48 or 96 h after beginning the exposure). RESULTS: Blood lipids showed, at 48 h stimulated animals, a significant increase of cholesterol associated to high density lipoproteins (HDL-C) than those observed at any other studied time. Free fatty acid serum presented at 24 h significant increases in comparison with control group. The other serum lipids, triacylglycerols and total cholesterol did not show differences between groups, at any time evaluated. No statistical differences were shown on total lipids of the liver but total cholesterol was elevated at 24 h with a significant decrease at 96 h (p = 0.026). The ELF-EMF stimulation increased the liver content of lipoperoxides at 24 h. CONCLUSION: Single exposures to ELF-EMF increases the serum values of HDL-C, the liver content of lipoperoxides and decreases total cholesterol of the liver. The mechanisms for the effects of ELF-EMF on lipid metabolism are not well understand yet, but could be associated to the nitric oxide synthase EMF-stimulation.

386

Effects on the nervous system by exposure to electromagnetic fields: experimental and clinical studies

Exposure to electromagnetic fields may cause various types of effects on nervous tissue, in severe cases even irreversible damage. The exposure conditions, i.e. frequency including type and extent of modulation, time, intensity, wave form, as well as shape, size and position of exposed subject and possible treatment with drugs, are factors determining if damage, acute or chronic, ultimately result. Long term exposure of newborn rabbits, rats and mice to electromagnetic fields of power frequency (10-14 kV/m; 50 or 60 Hz; sinusoidal wave form; 21-24 h per day) may cause affection and even damage to the nervous system. Large nerve cells showed reactive changes such as lamellar bodies and cytoskeletal alteration to an extent varying with exposure conditions. Reactive neuroglial changes as well as increase in neuroglial marker proteins could concomitantly be demonstrated. The changes seemed to be reversible although we only have incomplete data available. Exposure in vitro of frog sciatic nerve to 16-60 Hz sinusoidal low current (50-1000 nA) for 17 h induced cytoskeletal changes. Exposure of rabbits to pulsed microwaves of moderate to high intensity (3.1 GHz; 300 Hz modulation; peak duration 1.4 usec with maximal peak intensity about 1000 times average; 55 mW/cm; SAR in the brain cortex about 20 W/kg; increase of temperature as measured by lightguide-equipped instruments in right brain hemisphere about 1-2 degrees C) during 1 h per day during three days resulted in no obvious initial changes in behaviour. Minimal acute dam- age could be demonstrated. However, after two to four months and later on both structural, immunohistochemical and biochemical changes could be documented. Radar technicians accidently and/or occupationally exposed to microwaves showed psychoneurological signs of affection as well as changes in cerebrospinal fluid protein pattern. No related changes have been noticed among matched controls. Exposure of nervous tissue to electromagnetic fields ranging from power frequency to microwaves may thus exert a wide range of effects, mostly by mechanisms we know little about.

387

Eigenvector methods for analysis of human PPG, ECG and EEG signals

This paper presents eigenvector methods for analysis of the photoplethysmogram (PPG), electrocardiogram (ECG), electroencephalogram (EEG) signals recorded in order to examine the effects of pulsed electromagnetic field (PEMF) at extremely low frequency (ELF) upon the human electrophysiological signal behavior. The features representing the PPG, ECG, EEG signals were obtained by using the eigenvector methods. In addition to this, the problem of selecting relevant features among the features available for the purpose of discrimination of the signals was dealt with. Some conclusions were drawn concerning the efficiency of the eigenvector methods as a feature extraction method used for representing the signals under study.

388

Electric and magnetic fields in stem cell research

Electromagnetic fields are inducers and directors in stem cell differentiation. Embryonic development is largely a matter of switching on the right gene, in the right place, and at the right time, and in this process a number of stem cell modifiers are involved. Among these modifiers, electromagnetic fields seem to have an important role to play.

389

Electric current generated by ultrasonically induced Lorentz force in biological media

The ions of solutions exposed to the propagation of ultrasound in the presence of a magnetic field experience Lorentz force. Their movement gives rise to a local electric current density, which is proportional to the electric conductivity of the medium. In vitro assessment of this current is performed using simple models of biological media. A constant magnetic field of 0.35 T and 500 kHz pulsed ultrasound are used. The sensing electrodes are exposed to neither the pressure wave nor the magnetic field, thus ensuring that the signal is not due to any undesirable electrode effect. The experimental results confirm that the current is proportional to the electrical conductivity of the medium. The changes in the measured current against the width of the measurement chamber show that the electrodes only collect a fraction of the current created within the medium. The magnitude of the measured current is 50nA in a saline solution of 0.5 S/m conductivity. The technique enabled the determination of the conductivity of a porcine blood sample against haematocrit. It is concluded that this type of measurement has the potential to allow the electrical conductivity of a medium to be determined using ultrasound.

390

Electric field driven flow in natural porous media

Electric fields were applied to fluid-saturated packed sand beds (0.23+/-0.03 mm average pore diameter), and the effects on the mobility of the water molecules were monitored using stimulated echo (STE) and pulsed field gradient (PFG) experiments. The mean flow velocity, averaged over the entire sample, is expected to vanish in closed systems, but the PFG and time dependent signal decay was enhanced beyond the effects of thermal diffusion, due to velocity dispersion. The internal flow generated by the electric field was shown to be fully time-reversible upon inverting the electric field polarity (for total flow times of up to 0.4s), a strong indication that the NMR detected displacements were mainly due to electro-osmotic flow (EOF). However, a comparison of the velocity dispersion for different electrolyte concentrations showed that the measured effect scaled with the applied power VI (V = voltage, I = electric current), rather than with the voltage alone, contrary to the prediction of the basic model for EOF in a single capillary channel.

391

Electric field-mediated glycophorin insertion in cell membrane is a localized event

Purified soluble glycophorin, an intrinsic protein, can be back 'electroinserted' in the membrane of Chinese hamster ovary cells by submitting the cell/protein mixture to short electric field pulses. Previous studies showed that this complex between pulsed cells and proteins, which is detected only when the cell membrane is electropermeabilized, was very stable. This strongly suggested that the protein was indeed inserted in the membrane. The basic processes involved in this phenomena are studied in the present work. The association is observed at the single cell level by means of videoimmunofluorescence. Electric field-mediated insertion occurs firstly in a limited patch of the cell surface, which size is in agreement with the prediction of Electropermeabilization theory. A free diffusion of the inserted proteins then follows on the cell surface. The diffusion coefficient is computed to be less than 10(-10) cm2/s as observed for transmembranous proteins. This slow process gives an homogeneous distribution of the inserted protein.

392

Electric fields in plasmas under pulsed currents

Electric fields in a plasma that conducts a high-current pulse are measured as a function of time and space. The experiment is performed using a coaxial configuration, in which a current rising to 160 kA in 100 ns is conducted through a plasma that prefills the region between two coaxial electrodes. The electric field is determined using laser spectroscopy and line-shape analysis. Plasma doping allows for three-dimensional spatially resolved measurements. The measured peak magnitude and propagation velocity of the electric field is found to match those of the Hall electric field, inferred from the magnetic-field front propagation measured previously.

393

Electrical fields enhance growth of cancer spheroids by reactive oxygen species and intracellular Ca2+

A single electrical field pulse (500 V/m) with a duration of 60 s increased tumor outgrowth over a postpulse period of 24 h. RNA staining with acridine orange showed a rise in RNA content in pulsed spheroids, indicating stimulation of cell cycle activity. The electropulse induced an intracellular Ca2+ concentration ([Ca2+]i) transient that started approximately 40 s after the onset of the electrical field. Neither the presence of extracellular Ni2+ (0.5 mM) nor the absence of extracellular Ca2+ impeded the [Ca2+]i rise. It was, however, totally blocked by thapsigargin (1 microM), indicating that the initial Ca2+ response is due to Ca2+ release from intracellular stores. The [Ca2+]i transient was paralleled by an increase in reactive oxygen species (ROS), as revealed using 2',7'-dichlorofluorescein diacetate as an indicator. The radical scavengers N-acetyl-L-cysteine (NAC)(20 mM) and dehydroascorbate (5 mM) inhibited both ROS production and the [Ca2+]i transient during electrical field treatment. The mitogenic activation was dependent on the rise in [Ca2+]i because inhibition of Ca2+ release during electrical field treatment by addition of either thapsigargin or NAC to the incubation medium abolished the observed effect. We conclude that a single, direct current electrical field pulse induces production of ROS, which in turn mediate Ca2+ release from intracellular stores and activate cell cycle activity in multicellular spheroids.

394

Electrical stimulation of osteonecrosis of the femoral head

Osteonecrosis of the femoral head in the adult is a progressive condition that, if untreated, usually results in femoral head collapse and secondary osteoarthritis. The experimental application of electrical and electromagnetic fields has been shown to favorably affect a number of biological processes pertinent to osteonecrosis of the femoral head and has led to several clinical trials. The condition has been treated by the application of electrical fields invasively by the surgical implantation of electrodes within the femoral head and noninvasively by capacitative or inductive coupling. This review describes results in osteonecrosis of the femoral head with these therapeutic techniques. Stimulation by means of inductive coupling with pulsed magnetic fields seems to be the most promising technique studied so far, but the optimal signal characteristics and device design are not yet known.

395

Electrical stimulation therapies for spinal fusions: current concepts

Electrical stimulation therapies have been used for more than 30 years to enhance spinal fusions. Although their positive effects on spinal fusions have been widely reported, the mechanisms of action of the technologies were only recently identified. Three types of technologies are available clinically: direct current, capacitive coupling, and inductive coupling. The latter is the basis of pulsed electromagnetic fields and combined magnetic fields. This review summarizes the current concepts on the mechanisms of action, animal and clinical studies, and cost justification for the use of electrical stimulation for spinal fusions. Scientific studies support the validity of electrical stimulation treatments. The mechanisms of action of each of the three electrical stimulation therapies are different. New data demonstrates that the upregulation of several growth factors may be responsible for the clinical success seen with the use of such technologies.

396

Electrical stimulation vs thermal effects in a complex electromagnetic environment

Studies linking exposure to low levels of radiofrequencies with adverse health effects, notwithstanding their present apparent inconsistency, have contributed to a steady improvement in the quality of evaluating that exposure. In complex electromagnetic environments, with a multitude of emissions of different frequencies acting simultaneously, knowledge of the spectral content is fundamental to evaluating human exposure to non-ionizing radiation. In the present work, we quantify the most significant spectral components in the frequency band 0.5-2200 MHz in an urban area. The measurements were made with a spectrum analyzer and monopole, biconical, and log-periodic antennas. Power density levels were calculated separately for the medium wave, short wave, and frequency modulation radio broadcasting bands, and for the television and GSM, DCS, and UMTS mobile telephony bands. The measured levels were compared with the ICNIRP reference levels for exposure to multiple frequency sources for thermal effects and electrical stimulation. The results showed the criterion limiting exposure on the basis of preventing electrical stimulation of peripheral nerves and muscles to be stricter (exposure quotient 24.7 10(-4)) than that based on thermal considerations (exposure quotient 0.16 10(-4)). The bands that contribute most to the latter are short wave, with 46.2%, and mobile telephony with 32.6% of the total exposure. In a complex electromagnetic environment, knowledge of the radiofrequency spectrum is essential in order to quantify the contribution of each type of emission to the public's exposure. It is also necessary to evaluate the electrical effects as well as the thermal effects because the criterion to limit exposure on the basis of the effect of the electrical stimulation of tissues is stricter than that based on thermal effects.

397

Electrochemical therapy of pelvic pain: effects of pulsed electromagnetic fields (PEMF) on tissue trauma

Unusually effective and long-lasting relief of pelvic pain of gynaecological origin has been obtained consistently by short exposures of affected areas to the application of a magnetic induction device producing short, sharp, magnetic-field pulses of a minimal amplitude to initiate the electrochemical phenomenon of electroporation within a 25 cm2 focal area. Treatments are short, fasting-acting, economical and in many instances have obviated surgery. This report describes typical cases such as dysmenorrhoea, endometriosis, ruptured ovarian cyst, acute lower urinary tract infection, post-operative haematoma, and persistent dyspareunia in which pulsed magnetic field treatment has not, in most cases, been supplemented by analgesic medication. Of 17 female patients presenting with a total of 20 episodes of pelvic pain, of which 11 episodes were acute, seven chronic and two acute as well as chronic, 16 patients representing 18 episodes (90%) experienced marked, even dramatic relief, while two patients representing two episodes reported less than complete pain relief.

398

Electrode microchamber for noninvasive perturbation of mammalian cells with nanosecond pulsed electric fields

Nanosecond pulsed electric fields can pass through the external membrane of biological cells and disturb fast-responding intracellular structures and processes. To enable real-time imaging and investigation of these phenomena, a microchamber with integral electrodes and optical path for observing individual cells exposed to ultrashort electric pulses was designed and fabricated utilizing photolithographic and microelectronic methods. SU-8 photoresist was patterned to form straight sidewalls from 10 to 30 microm in height, with gold film deposited on the top and sidewalls for conductive, nonreactive electrodes and a uniform electric field. Channel dimensions (10-30 microm x 100 microm x 12 000 microm) are suitable for observations of mammalian cells during nanosecond, megavolt-per-meter pulsed electric field exposure. Experimental studies utilizing the electrode microchamber include live-cell imaging of nanoelectropulse-induced intracellular calcium bursts and membrane phospholipid translocation.

399

Electroendocytosis: exposure of cells to pulsed low electric fields enhances adsorption and uptake of macromolecules

This study demonstrates alteration of cell surface, leading to enhanced adsorption of macromolecules (bovine serum albumin (BSA), dextran, and DNA), after the exposure of cells to unipolar pulsed low electric fields (LEF). Modification of the adsorptive properties of the cell membrane also stems from the observation of LEF-induced cell-cell aggregation. Analysis of the adsorption isotherms of BSA-fluorescein isothiocyanate (FITC) to the surface of COS 5-7 cells reveals that the stimulated adsorption can be attributed to LEF-induced increase in the capacity of both specific and nonspecific binding. The enhanced adsorption was consequently followed by increased uptake. At 20 V/cm the maximal binding and subsequent uptake of BSA-FITC attached to specific sites are 6.5- and 7.4-fold higher than in controls, respectively. The nonspecific LEF-induced binding and uptake of BSA are 34- and 5.2-fold higher than in controls. LEF-enhanced adsorption is a temperature-independent process, whereas LEF-induced uptake is a temperature-dependent one that is abolished at 4 degrees C. The stimulation of adsorption and uptake is reversible, revealing similar decay kinetics at room temperature. It is suggested that electrophoretic segregation of charged components in the outer leaflet of the cell membrane is responsible for both enhanced adsorption and stimulated uptake via changes of the membrane elastic properties that enhance budding and fission processes.

400

Electroinduced extraction of beta-galactosidase from Kluyveromyces lactis

A new methodology for the extraction of beta-galactosidase from the yeast Kluyveromyces lactis was obtained by electropulsation. The application of a series of electric pulses (2 ms duration, 1 Hz frequency, and 4-4.5 kV/cm field strength) to fresh cells suspended in deionized water, followed by incubation in PBS, led to a spontaneous slow release of enzyme at a yield of 75-80% without any further treatment. Most of the enzyme was extracted within 8 h after electropulsation. This release was dependent on the growth phase. The specific activity of beta-galactosidase in the supernatant of pulsed cells was higher by a factor of 1.5-1.7 in comparison with crude extract.

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