iMRS 2000 - PEMF Publications
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PEMF Publications

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601

In vitro low frequency electromagnetic field effect on fast axonal transport

The objective of this study was to evaluate the effects of a low frequency electromagnetic field on fast axonal transport for future neuroprosthetic applications. Changes in speeds and densities of retrograde fast organelle transport in rat sciatic nerve preparations were measured in vitro upon exposure to 15 and 50 Hz pulsed magnetic fields with peak intensities of 4.4 and 8.8 mT. Maximum current density of the induced eddy current was calculated to be about 40 microA/cm2. Video enhanced differential interference contrast microscopy was used to record axons supporting active organelle transport. Strong effects were observed in myelinated axons (cessation of transport in up to 10 min). Such effects may eventually be used as part of a neuroprosthesis to noninvasively modify or couple to various parts of the nervous system.

602

In vivo 3-D distributions of electric fields in pig skin with rectangular pulse electrical current stimulation (RPECS)

We developed stimulating and detecting electrodes. We experimentally examined three dimensional (3-D) distributions of electric fields in living pig skin under and around the stimulating electrodes with the detecting electrodes and rectangular pulsed electrical current stimulation (RPECS). We verified our previous physical assumption, E approximately I/(A sigma dz), in the skin under the electrode, where E, I, A and sigma dz respectively represent the electric field, the externally imposed peak current, the cross sectional area of the stimulating electrode and the perpendicular conductivity of the skin. Pulses were 30 mA, 140 microseconds and 128 pulses per second (pps). These parameters were previously used in our laboratory to enhance cutaneous regeneration, in vivo, with RPECS.

603

In vivo and in vitro effects of a pulsed electromagnetic field on net calcium flux in rat calvarial bone

Although PEMF's have been found to promote fracture healing and to modulate the activity of bone cells in vitro, effects on bone metabolism are largely unexplored. A bioassay using neonatal rat calvarial bone was used to determine the early effects of a pulsing electromagnetic field (PEMF) exposure in vivo and in vitro on bone metabolic calcium exchange. Bone discs taken from whole body exposed animals (0-4 hours) show a log exposure time-dependent average increase in net Ca uptake in the 0-50% range (r2 = 0.83). This increase could be detected immediately after exposure and also after 24 hours, but not 48 hours later. Animals given whole body PEMF exposure also showed a decrease in serum calcium and did not elevate serum Ca after administration of exogenous parathyroid hormone (PTH). Bone discs from untreated rats, exposed to PEMF for 15 minutes in vitro and then assayed, showed net Ca uptake increases of a similar magnitude and also were refractory to the Ca-releasing effect of PTH. Unexposed discs responded normally to PTH by decreasing net Ca uptake. Treatment of calvarial discs with calcitonin or acetazolamide, both of which inactivate osteoclasts, made the bone refractory to further increases in Ca uptake by PEMF. These results suggest that PEMF exposure produces PTH-refractory osteoclastics and has a relatively rapid effect on increasing net bone Ca uptake, putatively due to a decrease in PTH/paracrine-mediated bone resorption.

604

In-vivo study on the harmful effect of the extremely low frequency unipolar pulsating magnetic field in mice

We studied the biological effect of a magnetic field on murine brain and kidney. Magnetic field we used was generated by Magno-DR apparatus (Hanil Co., Korea) which produced a high density unipolar square pulsating magnetic field, about 0.3 approximately 0.5 Tesla at 7 Hertz. Animals were placed in the chamber of the machine for various times from 4 hours to 24 hours. Histological sections of brain and kidney were made after perfusion fixation with paraformaldehyde. The light microscopic examination showed eosinophilic change of cytoplasm and positive immunohistochemical reaction to amyloid precursor protein in the neurons of the cerebral cortex. However, the thalamus and brain stem were less affected. The changes in the brain was seen in the mouse exposed more than 12 hours. The renal tubular epithelium showed degenerated tubules scattered in cortical area but little change was noted in glomeruli in the cortex and collecting tubules in the medulla. Immunohistochemistry of the kidney showed weakly positive reaction for the amyloid precursor protein in the distal tubular epithelium after 4 hours of exposure. These data suggest that strong pulsating magnetic fields could induce deleterious effect on the murine brain tissue and renal cortical tubules.

605

Inactivation of Bacteria and Spores by Pulse Electric Field and High Pressure CO2 at Low Temperature

Abstract: The common methods for inactivation of bacteria involve heating or exposure to toxic chemicals. These methods are not suitable for heat-sensitive materials, food, and pharmaceutical products. Recently, a complete inactivation of many microorganisms was achieved with high-pressure carbon dioxide at ambient temperature and in the absence of organic solvent and irradiation. The inactivation of spores with CO2 required long residence time and high temperatures, such as 60°C. In this study the synergistic effect of pulsed electric field (PEF) in combination with high-pressure CO2 for inactivation was investigated. The bacteria Escherichia coli, Staphylococcus aureus, and Bacillus cereus were suspended in glycerol solution and treated in the first step with PEF (up to 25 KV/cm) and then with highpressure CO2 not higher than 40°C and 200 bar. The inactivation efficiency was determined by counting the colony formation units of control and sample. Samples of the cells subjected to PEF treatment alone and in combination with CO2 treatment were examined by scanning electron microscopy to determine the effect of the processes on the cell wall. Experimental results indicate that the viability decreased with increasing electrical field strength and number of pulses. A further batch treatment with supercritical CO2 lead to complete inactivation of bacterial species and decreased the count of the spores by at least three orders of magnitude, the inactivation being enhanced by an increase of contact time between CO2 and the sample. A synergistic effect between the pulsed electric field and the high-pressure CO2 was evident in all the species treated. The new low temperature process is an alternative for pasteurization of thermally labile compounds such as protein and plasma and minimizes denaturation of important nutrient compounds in the liquid media.

606

Inactivation of bacteria and spores by pulse electric field and high pressure CO2 at low temperature

The common methods for inactivation of bacteria involve heating or exposure to toxic chemicals. These methods are not suitable for heat-sensitive materials, food, and pharmaceutical products. Recently, a complete inactivation of many microorganisms was achieved with high-pressure carbon dioxide at ambient temperature and in the absence of organic solvent and irradiation. The inactivation of spores with CO(2) required long residence time and high temperatures, such as 60 degrees C. In this study the synergistic effect of pulsed electric field (PEF) in combination with high-pressure CO(2) for inactivation was investigated. The bacteria Escherichia coli, Staphylococcus aureus, and Bacillus cereus were suspended in glycerol solution and treated in the first step with PEF (up to 25 KV/cm) and then with high-pressure CO(2) not higher than 40 degrees C and 200 bar. The inactivation efficiency was determined by counting the colony formation units of control and sample. Samples of the cells subjected to PEF treatment alone and in combination with CO(2) treatment were examined by scanning electron microscopy to determine the effect of the processes on the cell wall. Experimental results indicate that the viability decreased with increasing electrical field strength and number of pulses. A further batch treatment with supercritical CO(2) lead to complete inactivation of bacterial species and decreased the count of the spores by at least three orders of magnitude, the inactivation being enhanced by an increase of contact time between CO(2) and the sample. A synergistic effect between the pulsed electric field and the high-pressure CO(2) was evident in all the species treated. The new low temperature process is an alternative for pasteurization of thermally labile compounds such as protein and plasma and minimizes denaturation of important nutrient compounds in the liquid media.

607

Inactivation of Saccharomyces cerevisiae suspended in orange juice using high-intensity pulsed electric fields

Saccharomyces cerevisiae is often associated with the spoilage of fruit juices. The purpose of this study was to evaluate the effect of high-intensity pulsed electric field (HIPEF) treatment on the survival of S. cerevisiae suspended in orange juice. Commercial heat-sterilized orange juice was inoculated with S. cerevisiae (CECT 1319) (10(8) CFU/ml) and then treated by HIPEFs. The effects of HIPEF parameters (electric field strength, treatment time, pulse polarity, frequency, and pulse width) were evaluated and compared to those of heat pasteurization (90 degrees C/min). In all of the HIPEF experiments, the temperature was kept below 39 degrees C. S. cerevisiae cell damage induced by HIPEF treatment was observed by electron microscopy. HIPEF treatment was effective for the inactivation of S. cerevisiae in orange juice at pasteurization levels. A maximum inactivation of a 5.1-log (CFU per milliliter) reduction was achieved after exposure of S. cerevisiae to HIPEFs for 1,000 micros (4-micros pulse width) at 35 kV/cm and 200 Hz in bipolar mode. Inactivation increased as both the field strength and treatment time increased. For the same electric field strength and treatment time, inactivation decreased when the frequency and pulse width were increased. Electric pulses applied in the bipolar mode were more effective than those in the monopolar mode for destroying S. cerevisiae. HIPEF processing inactivated S. cerevisiae in orange juice, and the extent of inactivation was similar to that obtained during thermal pasteurization. HIPEF treatments caused membrane damage and had a profound effect on the intracellular organization of S. cerevisiae.

608

Inactivation of Salmonella enterica Ser. Enteritidis in tomato juice by combining of high-intensity pulsed electric fields with natural antimicrobials

The effect of high-intensity pulsed electric field (HIPEF) treatment (35kV/cm, 4 mus pulse length in bipolar mode without exceeding 38 degrees C) as influenced by treatment time (200, 600, and 1000 micros) and pulse frequency (100, 150, and 200 Hz) for inactivating Salmonella enterica ser. Enteritidis inoculated in tomato juice was evaluated. Similarly, the effect of combining HIPEF treatment with citric acid (0.5%, 1.0%, 1.5%, and 2.0%[wt/vol]) or cinnamon bark oil (0.05%, 0.10%, 0.2%, and 0.3%[vol/vol]) as natural antimicrobials against S. Enteritidis in tomato juice was also studied. Higher treatment time and lower pulse frequency produced the greater microbial inactivation. Maximum inactivation of S. Enteritidis (4.184 log(10) units) in tomato juice by HIPEF was achieved when 1000 micros and 100 Hz of treatment time and pulse frequency, respectively, were applied. However, a greater microbial inactivation was found when S. Enteritidis was previously exposed to citric acid or cinnamon bark oil for 1 h in tomato juice. Synergistic effects were observed in HIPEF and natural antimicrobials. Nevertheless, combinations of HIPEF treatment with 2.0% of citric acid or 0.1% of cinnamon bark oil were needed for inactivating S. Enteritidis by more than 5.0 log(10) units (5.08 and 6.04 log(10) reductions, respectively). Therefore, combinations of HIPEF with organic acids or essential oils seem to be a promising method to achieve the pasteurization in these kinds of products.

609

Inactivation of Salmonella Typhimurium in orange juice containing antimicrobial agents by pulsed electric field

Combinations of different hurdles, including moderately high temperatures (<60 degrees C), antimicrobial compounds, and pulsed electric field (PEF) treatment, to reduce Salmonella in pasteurized and freshly squeezed orange juices (with and without pulp) were explored. Populations of Salmonella Typhimurium were found to decrease with an increase in pulse number and treatment temperature. At a field strength of 90 kV/cm, a pulse number of 20, and a temperature of 45 degrees C, PEF treatment did not have a notable effect on cell viability or injury. At and above 46 degrees C, however, cell death and injury were greatly increased. Salmonella numbers were reduced by 5.9 log cycles in freshly squeezed orange juice (without pulp) treated at 90 kV/cm, 50 pulses, and 55 degrees C. When PEF treatment was carried out in the presence of nisin (100 U/ml of orange juice), lysozyme (2,400 U/ml), or a mixture of nisin (27.5 U/ml) and lysozyme (690 U/ml), cell viability loss was increased by an additional 0.04 to 2.75 log cycles. The combination of nisin and lysozyme had a more pronounced bactericidal effect than did either nisin or lysozyme alone. An additional Salmonella count reduction of at least 1.37 log cycles was achieved when the two antimicrobial agents were used in combination. No significant difference (P > 0.05) in cell death was attained by lowering the pH value; only cell injury increased. Inactivation by PEF was significantly more extensive (P < 0.05) in pasteurized orange juice than in freshly squeezed orange juice under the same treatment conditions. This increase might be due to the effect of the chemical composition of the juices.

610

Inconsistent suppression of nocturnal pineal melatonin synthesis and serum melatonin levels in rats exposed to pulsed DC magnetic fields

The purpose of these experiments was to determine whether the exposure of rats at night to pulsed DC magnetic fields (MF) would influence the nocturnal production and secretion of melatonin, as indicated by pineal N-acetyltransferase (NAT) activity (the rate limiting enzyme in melatonin production) and pineal and serum melatonin levels. By using a computer-driven exposure system, 15 experiments were conducted. MF exposure onset was always during the night, with the duration of exposure varying from 15 to 120 min. A variety of field strengths, ranging from 50 to 500 microT (0.5 to 5.0 G) were used with the bulk of the studies being conducted using a 100 microT (1.0 G) field. During the interval of DC MF exposure, the field was turned on and off at 1-s intervals with a rise/fall time constant of 5 ms. Because the studies were performed during the night, all procedures were carried out under weak red light (intensity of <5 microW/cm2). At the conclusion of each study, a blood sample and the pineal gland were collected for analysis of serum melatonin titers and pineal NAT and melatonin levels. The outcome of individual studies varied. Of the 23 cases in which pineal NAT activity, pineal melatonin, and serum melatonin levels were measured, the following results were obtained; in 5 cases (21.7%) pineal NAT activity was depressed, in 2 cases (8.7%) studies pineal melatonin levels were lowered, and in 10 cases (43.5%) serum melatonin concentrations were reduced. Never was there a measured rise in any of the end points that were considered in this study. The magnitudes of the reductions were not correlated with field strength (i.e., no dose-response relationships were apparent), and likewise the reductions could not be correlated with the season of the year (experiments conducted at 12-month intervals under identical exposure conditions yielded different results). Duration of exposure also seemed not to be a factor in the degree of melatonin suppression. The inconsistency of the results does not permit the conclusion that pineal melatonin production or release are routinely influenced by pulsed DC MF exposure. In the current series of studies, a suppression of serum melatonin sometimes occurred in the absence of any apparent change in the synthesis of this indoleamine within the pineal gland (no alteration in either pineal NAT activity or pineal melatonin levels). Because melatonin is a direct free radical scavenger, the drop in serum melatonin could theoretically be explained by an increased uptake of melatonin by tissues that were experiencing augmented levels of free radicals as a consequence of MF exposure. This hypothetical possibly requires additional experimental documentation.

611

Increased analgesia to thermal stimuli in rats after brief exposures to complex pulsed 1 microTesla magnetic fields

Nociceptive thresholds to a 55 degrees C hot surface were measured for female Wistar rats before treatments and 30 min. and 60 min. after the treatments. After injection with either naloxone or saline following baseline measurements, the rats were exposed for 30 min. to either sham fields or to weak (about 1 microTesla) burst-firing magnetic fields composed of 230 points (4 msec. per point) presented once every 3 sec. The rats that had received the burst-firing magnetic fields exhibited elevated nociceptive thresholds that explained about 50% of the variance. A second pattern, designed after the behaviour of individual thalamic neurons during nociceptive input and called the "activity rhythm magnetic field" produced only a transient analgesic effect. These results replicated previous studies and suggest that weak, extremely low frequency, pulsed magnetic fields with biorelevant temporal structures may have utility as adjuncts for treatment of pain.

612

Induced dielectric-force-effect by 50 Hz strong electric field on living tissue

The main objective of this paper is to study on the fields, resultant forces, and the dielectric substances in biologic tissues. Additionally, to unveil the possible mechanism which affects on major biological activities were examined. In the scientific literature, there are many studies conducted with low frequency Electromagnetic Fields (MFs), Static Magnetic Fields (SMFs), and Pulsed Electromagnetic Fields (PEMFs). However, we face in some cases; merely electric fields may be effective on biological functions (around 10 kV/m). Parallel plate exposure system was chosen as a model in this paper. In order to overcome the difficulty of generating virtual homogenous low frequency ac (power frequencies) or dc fields, a pair of appropriately designed parallel plates exposure model may be mighty tool. In this study, an important assumption, with deriving an equation that possible explanation for heat rise in a living tissue, has been made. Consequently it has been assumed that the field E(loc) may be responsible both for the induced and oriented polarization.

613

Induction of protein-like molecular architecture by self-assembly processes

One of the most intriguing self-assembly processes is the folding of peptide chains into native protein structures. We have developed a method for building protein-like structural motifs that incorporate sequences of biological interest. A lipophilic moiety is attached onto an N(alpha)-amino group of a peptide chain, resulting in a 'peptide-amphiphile'. The alignment of amphiphilic compounds at the lipid solvent interface is used to facilitate peptide alignment and structure initiation and propagation. Peptide-amphiphiles containing potentially triple-helical structural motifs have been synthesized. The resultant head group structures have been characterized by circular dichroism and NMR spectroscopies. Evidence for a self-assembly process of peptide-amphiphiles has been obtained from: (a) circular dichroism spectra and melting curves characteristic of triple-helices, (b) one- and two-dimensional NMR spectra indicative of stable triple-helical structure at low temperatures and melted triple-helices at high temperatures, and (c) pulsed-field gradient NMR experiments demonstrating different self-diffusion coefficients between proposed triple-helical and non-triple-helical species. The peptide-amphiphiles described here provide a simple approach for building stable protein structural motifs using peptide head groups.

614

Influence of 1 and 25 Hz, 1.5 mT magnetic fields on antitumor drug potency in a human adenocarcinoma cell line

The resistance of tumor cells to antineoplastic agents is a major obstacle during cancer chemotherapy. Many authors have observed that some exposure protocols to pulsed electromagnetic fields (PEMF) can alter the efficacy of anticancer drugs; nevertheless, the observations are not clear. We have evaluated whether a group of PEMF pulses (1.5 mT peak, repeated at 1 and 25 Hz) produces alterations of drug potency on a multidrug resistant human colon adenocarcinoma (HCA) cell line, HCA-2/1(cch). The experiments were performed including (a) exposures to drug and PEMF exposure for 1 h at the same time, (b) drug exposure for 1 h, and then exposure to PEMF for the next 2 days (2 h/day). Drugs used were vincristine (VCR), mitomycin C (MMC), and cisplatin. Cell viability was measured by the neutral red stain cytotoxicity test. The results obtained were: (a) The 1 Hz PEMF increased VCR cytotoxicity (P < 0.01), exhibiting 6.1% of survival at 47.5 microg/ml, the highest dose for which sham exposed groups showed a 19.8% of survival. For MMC at 47.5 microg/ml, the % of survival changed significantly from 19.2% in sham exposed groups to 5.3% using 25 Hz (P < 0.001). Cisplatin showed a significant reduction in the % of survival (44.2-39.1%, P < 0.05) at 25 Hz and 47.5 microg/ml, and (b) Minor significant alterations were observed after nonsimultaneous exposure of cells to PEMF and drug. The data indicate that PEMF can induce modulation of cytostatic agents in HCA-2/1(cch), with an increased effect when PEMF was applied at the same time as the drug. The type of drug, dose, frequency, and duration of PEMF exposure could influence this modulation.

615

Influence of 50 Hz magnetic field on human heart rate variability: linear and nonlinear analysis

This study investigated the problem of the influence of 50 Hz magnetic field (MF) on human heart rate variability (HRV). The exposure system was a commercial device for magnetotherapy, generating field of the strength of 500 microT at the center of the coil, 150-200 microT at the position of human subjects' heart and 20-30 microT at the position of subjects' head. The exposure protocols, applied randomly, were either "half hour MF-off/half hour MF-on" or "half hour MF-off/half hour MF-off." The phonocardiographic (PhCG) signal of 15 volunteers were obtained during exposure and used for calculation of time-domain HRV parameters (mean time between heart beats (N-N), standard deviation of time between heart beats (SDNN), and the number of differences of successive beat-to-beat intervals greater than 50 ms, divided by the total number of beat-to-beat intervals (pNN50)) and nonlinear HRV measures (approximate entropy (ApEn), detrended fluctuation scaling exponents). The protocol MF-off/MF-on was applied in nine subjects. Repeated measures ANOVA (RMANOVA) performed for Mf-off/MF-off protocol indicated no statistical difference among four 15 min intervals of HRV data (P value >20% for all parameters except for N-N, where P = 3.7%). RMANOVA followed by the post hoc Tukey test performed for Mf-off/MF-on protocol indicated a statistically significant difference during MF on for N-N (8% increase, P <.1%), SDNN (40% increase, P = 1.1%), and pNN50 (110% increase, P <.1%). The results of the analysis indicate that the changes of these parameters could be associated with the influence of MF.

616

Influence of a 902.4 MHz GSM signal on the human visual system: investigation of the discrimination threshold

The proximity of a mobile phone to the human eye raises the question as to whether radiofrequency (RF) electromagnetic fields (EMF) affect the visual system. A basic characteristic of the human eye is its light sensitivity, making the visual discrimination threshold (VDThr) a suitable parameter for the investigation of potential effects of RF exposure on the eye. The VDThr was measured for 33 subjects under standardized conditions. Each subject took part in two experiments (RF-exposure and sham-exposure experiment) on different days. In each experiment, the VDThr was measured continuously in time intervals of about 10 s for two periods of 30 min, having a break of 5 min in between. The sequence of the two experiments was randomized, and the study was single blinded. During the RF exposure, a GSM signal of 902.4 MHz (pulsed with 217 Hz) was applied to the subjects. The power flux density of the electromagnetic field at the subject location (in the absence of the subject) was 1 W/m(2), and numerical dosimetry calculations determined corresponding maximum local averaged specific absorption rate (SAR) values in the retina of SAR(1 g) = 0.007 W/kg and SAR(10 g) = 0.003 W/kg. No statistically significant differences in the VDThr were found in comparing the data obtained for RF exposure with those for sham exposure.

617

Influence of a radiofrequency electromagnetic field on cardiovascular and hormonal parameters of the autonomic nervous system in healthy individuals

The potential health risks of radiofrequency electromagnetic fields (EMFs) emitted by mobile phones are of considerable public interest. The present study investigated the hypothesis, based on the results of our previous study, that exposure to EMFs can increase sympathetic vasoconstrictor activity. Forty healthy young males and females underwent a single-blind, placebo-controlled protocol once on each of two different days. Each investigation included successive periods of placebo and EMF exposure, given in a randomized order. The exposure was implemented by a GSM-like signal (900 MHz, pulsed with 217 Hz, 2 W) using a mobile phone mounted on the right-hand side of the head in a typical telephoning position. Each period of placebo exposure and of EMF exposure consisted of 20 min of supine rest, 10 min of 70 degrees upright tilt on a tilt table, and another 20 min of supine rest. Blood pressure, heart rate and cutaneous capillary perfusion were measured continuously. In addition, serum levels of norepinephrine, epinephrine, cortisol and endothelin were analyzed in venous blood samples taken every 10 min. Similar to the previous study, systolic and diastolic blood pressure each showed slow, continuous, statistically significant increases of about 5 mmHg during the course of the protocol. All other parameters either decreased in parallel or remained constant. However, analysis of variance showed that the changes in blood pressure and in all other parameters were independent of the EMF exposure. These findings do not support the assumption of a nonthermal influence of EMFs emitted by mobile phones on the cardiovascular autonomic nervous system in healthy humans.

618

Influence of different types of electromagnetic fields on skin reparatory processes in experimental animals

Wound healing is a very complex process, some phases of which have only recently been explained. Magnetic and electromagnetic fields can modulate this process in a non-thermal way. The aim of this research was to compare the influence of constant and pulsed electromagnetic fields and low-level laser therapy (LLLT) on wound healing in experimental animals. The experiment was conducted on 120 laboratory rats divided into four groups of 30 animals each (constant electromagnetic field, pulsed electromagnetic field, LLLT and control group). It lasted for 21 days. Under the influence of the constant electromagnetic field the healing of the skin defect was accelerated in comparison with the control group. The difference was statistically significant in all the weeks of the experiment at the P < 0.01 level. Accelerated healing was also observed under the influence of the pulsed electromagnetic field (P < 0.05). In the group of animals exposed to LLLT, the healing of the skin defect was faster than in the control group. The statistical significance was at the P < 0.05 level. Different types of electromagnetic fields have a promoting effect on the wound healing process.

619

Influence of electromagnetic fields on bone fracture in rats: role of CAPE

OBJECTIVE: To study the effects of radiation emitted by mobile phones on bone strength and caffeic acid phenethyl ester (CAPE) on the changes induced by radiation. METHODS: Forty-eight Sprague-Dawley rats were divided into five groups. Rats in the control group (first group) were left within the experimental setup for 30 min/day for 28 days without radiation exposure. Nine hundred MHz radiation group was broke down into 2 subgroups (group 1/2). Both subgroups were exposed to radiation for 28 days (30 min/day). The next group was also divided into 2 subgroups (group 3/4). Each was exposed to 1800 MHz of radiation for 28 days (30 min/day). The third and fifth groups were also treated with CAPE for 28 days. Treatment groups received ip caffeic acid phenethyl ester (10 micromol/kg per day) before radiation session. Bone fracture was analyzed. RESULTS: Breaking force, bending strength, and total fracture energy decreased in the irradiated groups but increased in the treatment groups. CONCLUSION: Radiation and CAPE can significantly improve bone.

620

Influence of electromagnetic fields on the enzyme activity of rheumatoid synovial fluid cells in vitro

Since positive clinical effects have been observed in the treatment of rheumatoid arthritis with electromagnetic fields of weak strength and low frequency range (magnetic field strength: 70 microT; frequency: 1.36-14.44 Hz), an attempt was made to analyse the effects of these electromagnetic fields on enzyme activity in monolayer cultures of rheumatoid synovial fluid cells after single irradiation of the cultures for 24 hours. We only investigated the matrix metalloproteinases (collagenase, gelatinase, proteinase 24.11 and aminopeptidases). It was found that electromagnetic fields of such a weak strength and low frequency range do not generally have a uniform effect on the activity of the different proteinases in vitro. While aminopeptidases do not show any great changes in activity, the peptidases hydrolysing N(2,4)-dinitrophenyl-peptide exhibit a distinct increase in activity in the late phase in culture medium without fetal calf serum. In the presence of fetal calf serum this effect is not observed and enzyme activity is diminished. Our experiments do not show whether such a phase-bound increase in the activity of proteinases in vitro is only one finding in a much broader range of effects of electromagnetic fields, or whether it is a specific effect of weak pulsed magnetic fields of 285 +/- 33 nT on enzyme activity after single irradiation. This question requires further elucidation.

621

Influence of magnetic fields on calcium salts crystal formation: an explanation of the 'pulsed electromagnetic field' technique for bone healing

In the search for a mechanism by means of which a magnetic field deparalyses non-unions and enhances bone tissue formation, the influence of continuous magnetic fields on the formation of calcium phosphate crystal seeds has been investigated. From this perspective, an explanation is given of a working mode in conventional equipment for pulsed electromagnetic field treatment; this is compared with multifunction equipment.

622

Influence of non-thermic AC magnetic fields on spore germination in a dimorphic fungus

The influence of weak pulsed magnetic fields of low frequencies on the germination rate of Mycotypha africana was tested. This fungus grows as a mycelium (M-culture) or in a yeast-like form (Y-culture) depending upon culture conditions. 5 h and 24 h of field application enhanced the germination rate in a Y-culture up to 2 or 3 times at low intensity levels and decreased it up to a factor 4 at the intensity level "4". M-cultures exhibited the same reaction pattern after 5 h exposition and no effect after 24 h exposition. The Y/M ratio is shifted by low field intensities towards the Y-form. The occurrence of stimulation as well as retardation by neighbouring intensities is discussed.

623

Influence of pulsed electromagnetic field with different pulse duty cycles on neurite outgrowth in PC12 rat pheochromocytoma cells

The influence of low frequency (50 Hz repetition rate) pulsed electromagnetic field (EMF) on PC12 cell neurite outgrowth in vitro was investigated in this study. We studied the percentage of neurite bearing cells, average length of neurites, and directivity of neurite outgrowth in PC12 cells cultured for 96 h in the presence of nerve growth factor (NGF). PC12 cells were exposed in one incubator to pulsed EMF at 1.36 mT (peak value) generated by a pair of Helmholtz coils, and the control samples were placed in another identical incubator. We found that the pulse duty cycle had significant effect on neurite outgrowth. Low (10%) pulse on-time significantly inhibited the percentage of neurite bearing cells, but at the same time increased the average length of neurites, while 100% on-time (DC) had exactly the opposite effects. Furthermore, we found that neurites were prone to extend along the direction of pulsed EMF with 10% pulse on-time. Our studies show that neurite outgrowth in PC12 cells is sensitive to the pulse duty and this sensitivity was associated with NGF concentration.

624

Influence of pulsed electromagnetic fields on healing of experimental colonic anastomosis

PURPOSE: The study investigated the influence of pulsed electromagnetic fields (PEMFs) on the mechanical strength and collagen content of uncomplicated colonic anastomosis in rats. METHODS: A standardized left colonic resection was performed 3 cm above the peritoneal reflection, and end-to-end anastomosis was constructed with eight interrupted inverting sutures. Beginning immediately after surgery, randomly assigned groups were exposed to one of the following: 1) 100 Hz (frequency), 1 mT (intensity) PEMFs with 16-hour on/8-hour off cycles (n = 8); 2) 100 Hz, 2 mT PEMFs with 16-hour on/8-hour off cycles (n = 8); 3) 100 Hz, 1 mT PEMFs with 6-hour on/6-hour off cycles (n = 6), whereas the control group (n = 10) received no PEMFs. Relaparatomy was performed at 72 hours postoperatively, and the bursting pressure of the anastomotic segment was recorded in situ. The hydroxyproline contents of the anastomotic and adjacent perianastomotic segments of equal lengths were determined. RESULTS: Mean bursting pressure values of the groups that received 100 Hz, 1 or 2 mT PEMFs with 16-hour on/8-hour off cycles (90.88 +/- 19.13 and 83.88 +/- 7.08 mmHg, respectively) were significantly higher than those of the control group (61.66 +/- 10.6 mmHg) and the group with 6-hour on/6-hour off cycles (64.83 +/- 7.36 mmHg; P < 0.05 for all comparisons). Hydroxyproline contents of the anastomotic and perianastomotic segments were consistently higher in the 16-hour on/8-hour off PEMF groups, compared with those of the corresponding segments of the control group. CONCLUSIONS: PEMFs applied externally to unrestrained rats within a "window of PEMF parameters" provided a significant gain in the mechanical strength of the colonic anastomosis, at least 72 hours post-operatively. Associated relative increases in the hydroxyproline contents of the (peri)anastomotic colonic segments suggest that an altered collagen metabolism might contribute to this enhancement of the anastomotic repair. Further investigations based on these preliminary data and the definition of the exact measures regarding the effects of PEMFs on biologic systems, in general, may lead to an efficient and new adjunctive modality in colorectal surgery.

625

Influence of pulsed electromagnetic fields on regenerating rat liver after partial hepatectomy

Partially hepatectomised rats have been exposed immediately after surgery and every 12 hours thereafter to pulsed extremely low frequency electromagnetic fields. Stereological analysis performed on electron micrographs has shown that the treatment limits the depletion of liver glycogen found in control untreated rats within the first post-operative day. The massive accumulation of lipid droplets found in control rats is also limited to about one half by exposing the animals to pulsed magnetic fields. The time taken for glycogen and lipid content to recover to values found at zero time decreases from seven to five days in animals undergoing treatment with pulsed electromagnetic fields. The liver wet weight and the total protein content show a pattern of changes which is consistent with the behaviour of glycogen and lipid content. Five days after operation the treated rats reach the values found at zero time, while control animals need seven days to reach the same values.

626

Influence of static magnetic fields on pain perception and sympathetic nerve activity in humans

Static and pulsed magnetic fields have been reported to have a variety of physiological effects. However, the effect of static magnetic fields on pain perception and sympathetic function is equivocal. To address this question, we measured pain perception during reproducible noxious stimuli during acute exposure to static magnets. Pain perception, muscle sympathetic nerve activity, mean arterial pressure, heart rate, and forearm blood velocity were measured during rest, isometric handgrip, postexercise muscle ischemia, and cold pressor test during magnet and placebo exposure in 15 subjects (25 +/- 1 yr; 8 men and 7 women) following 1 h of exposure. During magnet exposure, subjects were placed on a mattress with 95 evenly spaced 0.06-T magnets imbedded in it. During placebo exposure, subjects were placed on an identical mattress without magnets. The order of the two exposure conditions was randomized. At rest, no significant differences were noted in muscle sympathetic nerve activity (8 +/- 1 and 7 +/- 1 bursts/min for magnet and placebo, respectively), mean arterial pressure (91 +/- 3 and 93 +/- 3 mmHg), heart rate (63 +/- 2 and 62 +/- 2 beats/min), and forearm blood velocity (3.0 +/- 0.3 and 2.6 +/- 0.3 cm/s). Magnets did not alter pain perception during the three stimuli. During all interventions, no significant differences between exposure conditions were found in muscle sympathetic nerve activity and hemodynamic measurements. These results indicate that acute exposure to static magnetic fields does not alter pain perception, sympathetic function, and hemodynamics at rest or during noxious stimuli.

628

Inhibition of proliferation of human lymphoma cells U937 by a 50 Hz electromagnetic field

Weak pulsating electromagnetically induced fields (PEMF) by Helmholtz coils changes cell metabolism, if cells are treated with a certain range of frequency and amplitude. The influence on proliferation of human histiocytic lymphoma cells U937 has been studied applying a sinusoidal 50 Hz field with amplitudes of the flux density B = 0.3 to 4.7 mT for 4 days. No difference between experiment and control was found in the region 0.3 and 2 mT. However, stronger fields (> or =2.5 mT) inhibit cell division. Fields > or =3.5 mT treatment kill > or =80% of the cell number at the beginning (1.5 x 10(5)/ml). This effect may be an electromagnetocally induced cell death as the first step for a non-invasive application on cell proliferation process.

629

Inhibitory effects of powerline-frequency (60 Hz) magnetic fields on pentylenetetrazol-induced seizures and mortality in rats.

The possibility that exposure to powerline frequency (60-Hz) magnetic fields might affect the form or intensity of epileptic seizures, induced by administration of pentylenetetrazol (PTZ) in rats, was examined. Male adult rats were exposed to either 60-Hz magnetic fields with intensities of up to 1.85 gauss (185 microT) or to a sham field condition, for 1 h prior to injections of PTZ (45-75 mg/kg). The subsequent seizures were monitored and recorded on videotape and any subsequent mortalities were noted. Exposure to 60-Hz magnetic fields prior to administration of PTZ was found to significantly (P less than 0.005) reduce the lethality of the drug-induced seizures. The LD50 for the sham-exposed group was 65.88 mg/kg, whereas for the 60-Hz magnetic field-exposed rats, the LD50 was 85.33 mg/kg. In some experiments exposure to the 1.0 and 1.5 gauss magnetic fields also produced significant (P less than 0.05) reductions in seizure durations. These findings suggest that acute exposure to low intensity 60-Hz magnetic fields has an inhibitory effect on the lethality and expression of PTZ-induced seizures in rats. Some possible mechanisms, which could account for these observed effects of magnetic field exposure on seizures, are discussed.

630

Initial exploration of pulsing electromagnetic fields for treatment of migraine

Two studies were conducted during which 23 patients with chronic migraine were exposed to pulsing electromagnetic fields over the inner thigh. In an open study, 11 subjects kept a two-week headache log before and after 2-3 weeks of exposure to pulsing electromagnetic fields for one hour per day, five days per week. The number of headaches per week decreased from 4.03 during the baseline period, to 0.43 during the initial two-week follow-up period, and to 0.14 during the extended follow-up which averaged 8.1 months. In a double-blind study, nine subjects kept a three-week log of headache activity and were randomly assigned to receive two weeks of real or placebo pulsing electromagnetic field exposures as described above. They were subsequently switched to two weeks of the other mode, after which they kept a final three week log. Three additional subjects in the blind study inadvertently received half power pulsing electromagnetic field exposures. The six subjects exposed to the actual device first show to change a headache activity from 3.32 per week to 0.58 per week. The three subjects exposed to only half the dose showed no change in headache activity. Large controlled studies should be performed to determine whether this intervention is actually effective.

631

Insertion of glycophorin A, a transmembraneous protein, in lipid bilayers can be mediated by electropermeabilization

Transmembraneous back-insertion of a solubilized membrane protein, glycophorin A, has been obtained in 1,2 dipalmitoyl-sn-glycero-3-phosphocholine (Pam2GroPCho) cell-size-like liposomes by submitting the lipid/protein mixture to calibrated electric field pulses. Field conditions which are prone to trigger glycophorin insertion are similar to those which mediate lipid layer electropermeabilization. The efflux of calcein, trapped in the liposomes during their preparation, was observed only when field strength is higher than 1.3 kV/cm. Electroinsertion was detected only above the same critical field intensity. Calcein efflux as well as glycophorin insertion were increased by increasing field intensity, pulse duration and/or number of pulses. Experimental evidence of protein insertion was provided by physico-chemical as well as biochemical methods. Direct observation of the pulsed vesicles under the microscope revealed the insertion by means of immunofluorescence and fluorescence. Electroinsertion of fluorescent glycophorin A revealed that the inner bilayers were also labeled. The gel-to-liquid phase transition temperature of Pam2GroPCho decreased after insertion but its cooperativity was not affected. A narrow 31P-NMR peak was observed after electroinsertion showing that the polar headgroups of phospholipids had been altered. Analysis of trypsin-digested peptides revealed that the two trans-orientations of the protein across the external lipid layer were present after electroinsertion. Localized perturbation of the polar headgroup region of phospholipids, which supports the transient permeabilization of lipid layers, allows spontaneous transinsertion of glycophorin across the lipid bilayers.

633

Intensity of extremely low-frequency electromagnetic fields produced in operating rooms during surgery at the standing position of anesthesiologists

BACKGROUND: Numerous electronic devices have been introduced into operating rooms. Although little is known about the relationship between exposure to electromagnetic fields and health hazards, several studies have demonstrated causal relationships between electromagnetic fields exposure and various symptoms, cancers, and other diseases. METHODS: This study was approved by the Institutional Review Board. The intensity of extremely low-frequency electromagnetic fields was measured during surgery with the extremely low-frequency electromagnetic field strength measurement system at the standing position of anesthesiologists in 18 operating rooms and analyzed with EMDEX analysis and graphical program (EMCALC 95; ENERTECH, Campbell, CA). RESULTS: The average measurement duration per operating room per day was 7.41 +/- 0.70 h (mean +/- SD). The average sample number of measurements was 888.11 +/- 82.75 per operating room. The average magnetic field was 5.83 +/- 5.23 milliGuass (mG) (range, 0.10-33.80 mG), with 70% of these levels 2 mG or greater. CONCLUSIONS: The authors' results indicate that anesthesiologists in operating rooms are exposed to extremely low-frequency electromagnetic field levels that exceed magnetic field intensity of 2 mG recommended by the Swedish Board for Technical Accreditation for production by computer monitors and detected 30 cm from them. It currently is not clear if this exposure has health effects on anesthesiologists and other operating room personnel.

634

Interaction of static and extremely low frequency electric and magnetic fields with living systems: health effects and research needs

Ambient static electric fields have not been reported to cause any direct adverse health effects, and so no further research in this area was deemed necessary by the attendees of an international conference held in Bologna, Italy in 1997.

635

Interfacial effect of extremely low frequency electromagnetic fields (EM-ELF) on the vaporization step of carbon dioxide from aqueous solutions of body simulated fluid (SBF)

Spontaneous processes in an aqueous solution of body simulated fluid (SBF) were monitored in closed vessel for a period of 1 month at 310 K, at atm pressure, and initial pH of 7.2, both with and without exposure to a square pulsed extremely low frequency electromagnetic fields (EM-ELF) of 250 microT, repeated at 75 Hz. The most important findings are that the SBF surface tension (gamma), evaluated under the EM-ELF field, is lower than the corresponding value measured without EM-ELF at any time. Furthermore, the pH of the exposed SBF is always more basic than that of the unexposed solution. As a consequence, when the EM-ELF is applied, calcium phosphate salts do not precipitate from the SBF solution for a period as long as 30 days. Behind all these experimental evidences there is only one mechanism: the vaporisation from the SBF-air interface of the CO(2)(aq) dissolved into the aqueous electrolyte solution. Thermodynamic analysis of these results establish that, at any given time, the difference, Delta, between the measured surface tensions with and without EM-ELF applied, gives the work of the electromagnetic forces to change the extent at which the CO(2)(aq) adsorbs at the liquid-air interface. It has been demonstrated that the work supply per second and per unit of area by the electromagnetic forces, 3.73 x 10(-10) mJ/s cm(2), is very near to the experimental slope in the plot Delta vs. t 1.7 x 10(-10) mJ/s cm(2). This leads to the conclusion that the EM-ELF fields have an interfacial effect on the concentration value of the CO(2) (aq) at the SBF-air interface. Because of that, the EM-ELF field is enhancing the CO(2) vaporisation rate; thus any other steps, which are a consequence of this mechanism, are changing. These results allow explanation of previous experiments concerning the precipitation of calcium carbonate from flowing hydrogen carbonate aqueous solution in the temperature range 353-373 K at a pressure of 0.1 MPa under the effect of static magnetic fields.

636

Interference of programmed electromagnetic stimulation with pacemakers and automatic implantable cardioverter defibrillators.

A commercially available magnetic therapy system, designed for clinical application as well as for private use without medical supervision, was examined with respect to its potential for causing electromagnetic interference with implantable pacemakers (PMs) and automatic implantable cardioverter defibrillators (AICDs). A sample of 15 PMs and 5 AICDs were experimentally investigated. Each of the implants was realistically positioned in a homogeneous, electrically passive torso phantom and exposed to the magnetic fields of the system’s applicators (whole body mat, cushion, and bar applicator). The detection thresholds of the implants were programmed to maximum sensitivity and both unipolar as well as bipolar electrode configurations were considered. The evaluation of possible interferences was derived from the internal event storages and pacing statistics recorded by the implants during exposure. Any ‘‘heart activity’’ recorded by the implants during exposure was interpreted as a potential interference, because the implant obviously misinterpreted the external interference signal as a physiological signal. Only cases without any recorded ‘‘heart activity’’ and with nominal pacing rates (as expected from the program parameter settings) of the implants were rated as ‘‘interference-free.’’ Exposure to the whole body mat (peak magnetic induction up to 265 mT) did not show an influence on PMs and AICD in any case. The cushion applicator at the highest field intensity (peak magnetic induction up to 360 mT) led to atrial sensing defects in four PM models with unipolar electrode configuration. Under bipolar electrode configuration no disturbances occurred. The bar applicator led to sensing problems and consecutively reduced pacing rates in all testedPMmodels under unipolar electrode configuration and maximum field intensity (peak magnetic induction up to 980 mT). Bipolar electrode configuration resolved the problem. The investigated AICDs did not show malfunctions under any investigated condition. In conclusion, the examined PEMF therapy system did not interfere with the investigated implantable cardiac devices with bipolar electrode configuration. However, unipolar electrode configuration in pacemakers seems to be potentially hazardous during application of the examined PEMF therapy system. Bioelectromagnetics 27:365–377, 2006.

637

Internal and external electromagnetic fields for on-axis Gaussian beam scattering from a uniaxial anisotropic sphere

Scattering of an on-axis Gaussian beam by a uniaxial anisotropic sphere is studied. The incident on-axis Gaussian beam is expanded in terms of spherical vector wave functions, and the beam shape coefficients are obtained by applying the local approximation. The internal fields of a uniaxial anisotropic sphere are proposed in the integrating form of the spherical vector wave functions by introducing the Fourier transform. Utilizing the continuous tangential boundary conditions, both the scattered and the internal field coefficients are derived analytically. Numerical calculations are presented. The effects of the beam width, beam waist center positioning, and anisotropy on scattering properties are analyzed. The internal and near-surface field distributions are also discussed, and the two eigenmodes are characterized. The continuity on the surface of a uniaxial anisotropic sphere is well confirmed.

638

International Commission for Protection Against Environmental Mutagens and Carcinogens. Power frequency electric and magnetic fields: a review of genetic toxicology

Epidemiologic studies have reported a modestly increased risk of childhood leukemia associated with certain electric power wire configurations. Since cancer likely involves DNA damage, this review discusses the evidence of direct and indirect genetic toxicity effects for both electric and magnetic fields at 50- and 60-Hz and miscellaneous pulsed exposures. Exposure conditions vary greatly among different end points measured, making comparisons and conclusions among experiments difficult. Although most of the available evidence does not suggest that electric and/or magnetic fields cause DNA damage, the existence of some positive findings and limitations in the set of studies carried out suggest a need for additional work.

639

Intracellular hyperthermia. A biophysical approach to cancer treatment via intracellular temperature and biophysical alterations

This paper introduces a new multi-disciplinary "intracellular" biophysical treatment of cancer. The basic concept uses locally induced heat energy after tumor phagocytosis of submicron particles whose composition permits magnetic excitation. The key to this process is the utilization of the cancer cell membrane to contain the energy within the cancer cell. Any magnetic or electric dipole contained within or introduced into the cell, or that is capable of being produced by an external field, can be used. Submicron particles are colloidally suspended, injected intravenously and are phagocytized by cancer cells. Application of an external high frequency or pulsed electromagnetic field then raises the particles' temperature thus generating intracellular heat in precise increments. This results in selective thermal destruction of cancer cells with little effect on normal cells. Experimental evidence is presented showing tumor cell destruction in spontaneous mammary tumors in Sprague Dawley rats. In addition, we suggest that certain biophysical properties are altered within the cancer cells and could be used to enhance this effect. Specific radioisotopes or tumor specific antibodies bound to particles or chemotherapeutic microspheres increase cancer cell sensitivity and affinity for these particles. This "intracellular" treatment of cancer has a wide potential range of applications.

640

Intracranial image-guided neurosurgery: experience with a new electromagnetic navigation system

BACKGROUND: The aim of image-guided neurosurgery is to accurately project computed tomography (CT) or magnetic resonance imaging (MRI) data into the operative field for defining anatomical landmarks, pathological structures and tumour margins. To achieve this end, different image-guided and computer-assisted, so-called "neuronavigation" systems have been developed in order to offer the neurosurgeon precise spatial information. METHOD: The present study reports on the experience gained with a prototype of the NEN-NeuroGuard neuronavigation system (Nicolet Biomedical, Madison, WI, USA). It utilises a pulsed DC electromagnetic field for determining the location in space of surgical instruments to which miniaturised sensors are attached. The system was evaluated in respect to its usefulness, ease of integration into standard neurosurgical procedures, reliability and accuracy. FINDINGS: The NEN-system was used with success in 24 intracranial procedures for lesions including both gliomas and cerebral metastases. It allowed real-time display of surgical manoeuvres on pre-operative CT or MR images without a stereotactic frame or a robotic arm. The mean registration error associated with MRI was 1.3 mm (RMS error) and 1.5 mm (RMS error) with CT-data. The average intra-operative target-localising error was 3.2 mm (+/- 1.5 mm SD). Thus, the equipment was of great help in planning and performing skin incisions and craniotomies as well as in reaching deep-seated lesions with a minimum of trauma. INTERPRETATION: The NEN-NeuroGuard system is a very user-friendly and reliable tool for image-guided neurosurgery. It does not have the limitations of a conventional stereotactic frame. Due to its electromagnetic technology it avoids the "line-of-sight" problem often met by optical navigation systems since its sensors remain active even when situated deep inside the skull or hidden, for example, by drapes or by the surgical microscope.

641

Intracranial measurement of current densities induced by transcranial magnetic stimulation in the human brain

Transcranial magnetic stimulation (TMS) is a non-invasive technique that uses the principle of electromagnetic induction to generate currents in the brain via pulsed magnetic fields. The magnitude of such induced currents is unknown. In this study we measured the TMS induced current densities in a patient with implanted depth electrodes for epilepsy monitoring. A maximum current density of 12 microA/cm2 was recorded at a depth of 1 cm from scalp surface with the optimum stimulation orientation used in the experiment and an intensity of 7% of the maximal stimulator output. During TMS we recorded relative current variations under different stimulating coil orientations and at different points in the subject's brain. The results were in accordance with current theoretical models. The induced currents decayed with distance form the coil and varied with alterations in coil orientations. These results provide novel insight into the physical and neurophysiological processes of TMS.

642

Intramembrane protein distribution in cell cultures is affected by 50 Hz pulsed magnetic fields

Intramembrane proteins (IMP) represent a class of proteins located in the lipid bilayer of the cell membrane which function as ion channels, enzymes or receptors. Since it has been argued that biological effects of extremely low frequency (ELF) electromagnetic fields are mediated by plasma membrane. this work was designed to study the possible effects of 50 Hz pulsed magnetic fields (PMF) of the type used to stimulate bone repair, on the distribution of IMP in the plasma membrane of Swiss NIH 3T3 fibroblasts. Evaluations were based on the calculation of a distribution factor, which allows discrimination between random, regular and clustered distribution of IMP, in electron microscope images of freeze-fractured membranes. The results indicate that cells exposed to PMF for more than two hours have a significant clustering of the IMP distribution compared to control unexposed cells.

643

Inversion recovery measurements in the presence of radiation damping and implications for evaluating contrast agents in magnetic resonance

Relaxation measurements performed at high magnetic field in magnetic resonance (MR) may be adversely affected by the influence of radiation damping in concentrated samples such as water. We consider how the measured value of T1 is affected by this phenomenon for a gadolinium-doped water sample and for an undoped water sample and consider the implications for evaluating contrast agents. A simple method involving the application of a pulsed field gradient to de-phase residual transverse components of the magnetization is shown to be an effective method for suppressing this effect. Given the central role that measurement of the T1 of water plays in the assessment of contrast agents as well as a host of other MR applications, care should always be employed when measuring and interpreting T1 measurements at high magnetic fields.

644

Investigation of practices and procedures in the use of therapeutic diathermy: a study from the physiotherapists' health and safety perspective

BACKGROUND AND PURPOSE: The safe use of therapeutic diathermy requires practices and procedures that ensure compliance to professional guidelines and clinical evidence. Inappropriate use may expose physiotherapists and other people in the vicinity of operating diathermy devices to stray radiofrequency electromagnetic fields, which can be a source of risk and may lead to adverse health effects. The aim of the present study was to investigate practices and procedures for therapeutic diathermy from a health and safety perspective. METHOD: A cross-sectional research design was used, this included a postal survey using a self-administered questionnaire and semi-structured observational visits to 46 physiotherapy departments in National Health Service (NHS) hospitals located in the south-east and south-west of England, including Greater London. RESULTS: Microwave diathermy was not available in the departments surveyed. Pulsed shortwave diathermy was available and was used more commonly than continuous shortwave diathermy. There were metallic objects in treatment cubicles used for pulsed shortwave diathermy and continuous shortwave diathermy. Shortwave diathermy devices created electromagnetic interference with a variety of electrical and medical devices. Physiotherapists reported that they did not stay in the treatment cubicle during the entire period of electrotherapy with pulsed shortwave diathermy or continous shortwave diathermy; pregnant physiotherapists reported that they did not use these devices. Electrotherapy with pulsed shortwave diathermy and continuous shortwave diathermy was not always administered on a wooden couch or chair. Electrotherapy was highest in those departments with the fewest physiotherapists. CONCLUSIONS: Departments report good practices and procedures regarding the use of therapeutic diathermy devices. However, field observations of practices and procedures, and the working environment, have identified issues with a potential to create health and safety problems, and these should be addressed.

645

Investigation of very slowly tumbling spin labels by nonlinear spin response techniques: theory and experiment for stationary electron electron double resonance

The investigation of very slowly tumbling spin labels by nonlinear electron spin response techniques is discussed. Such techniques permit characterization of rotational processes with correlation times from 10(-3) to 10(-7) sec even though the linear spin response (ESR) technique is insensitive to motion in this region. Nonlinear techniques fall into two categories: (a) Techniques (referred to as passage techniques) in which the distribution of saturation throughout the spin system is determined both by the applied magnetic field modulation of the resonance condition and by the modulation of the resonance frequency induced by the molecular motion. The time dependence of this distribution produces phase and amplitude changes in the observed signals. (b) Techniques that measure the integral of the distribution function of the time required for saturated spin packets to move between pumped and observed portions of the spectrum [stationary and pulsed electron electron double resonance (ELDOR) techniques]. Quantitative analysis of passage ESR and stationary ELDOR techniques can be accomplished employing a density matrix treatment that explicitly includes the interaction of the spins with applied radiation and modulation fields. The effect of molecular motion inducing a random modulation of the anisotropic spin interactions can be calculated by describing the motion by the diffusion equation appropriate to the motional model assumed. For infinitesimal steps the eigen-functions of the diffusion operator are known analytically, while for random motion of arbitrary step size they are determined by diagonalizing the transition matrix appropriate for the step model used. The present communication reports investigation of the rotational diffusion of the spin label probes 2,2,6,6-tetramethyl-4-piperidinol-1-oxyl and 17beta-hydroxy-4',4'-dimethylspiro-[5alpha-androstane-3,2'-oxazolidin]-3'- oxyl in sec-butylbenzene. Experimental spectra are compared with computer simulations of spectra carried out for isotropic Brownian (limit of infinitesimal step size) and free diffusion (arbitrary step size) models.

646

Is cochlear outer hair cell function affected by mobile telephone radiation?

Mobile telephones emit high-frequency pulsed electromagnetic fields (PEMF). These are known to have measurable biological effects, and possible effects on the auditory system. Otoacoustic emissions give an indication of the functional state of the auditory system. Otoacoustics are known to be highly specific for the individual when the test pulse is identical. In this way, subtle changes in the ear can be detected. We investigated whether there is a measurable effect on Otoacoustic emissions from PEMF radiation. A total of 12 volunteers were recruited who had normal hearing; confirmed by pure tone audiometry. An Otoacoustic emission trace was obtained. The test subjects were exposed to a mobile telephone that was placed over the test ears mastoid process. The subjects had Otoacoustic emissions measured without the telephone and again on receive and transmit. There was no change in the trace signature during the test. There was no statistically significant change in the trace figures. This would indicate that PEMF from commonly available hand held mobile telephones have no measurable effect on the outer hair cell function during the time of use.

647

Is postmenopausal osteoporosis related to pineal gland functions?

There is currently considerable interest in the pathogenesis of postmenopausal osteoporosis, which is the most common metabolic bone disease. Osteoporosis affects approximately 20 million persons in the United States, 90% of whom are postmenopausal women. Although there is evidence that estrogen deficiency is an important contributory factor, the pathogenesis of osteoporosis is multifactorial and presently poorly understood. There is evidence that pineal melatonin is an anti-aging hormone and that the menopause is associated with a substantial decline in melatonin secretion and an increased rate of pineal calcification. Animal data indicate that pineal melatonin is involved in the regulation of calcium and phosphorus metabolism by stimulating the activity of the parathyroid glands and by inhibiting calcitonin release and inhibiting prostaglandin synthesis. Hence, the pineal gland may function as a "fine tuner" of calcium homeostasis. In the following communication, we propose that the fall of melatonin plasma levels during the early stage of menopause may be an important contributory factor in the development of postmenopausal osteoporosis. Consequently, plasma melatonin levels taken in the early menopause could be used as an indicator or perhaps as a marker for susceptibility to postmenopausal osteoporosis. Moreover, light therapy, administration of oral melatonin (2.5 mg at night) or agents which induce a sustained release of melatonin secretion such as 5-methoxypsoralen, could be useful agents in the prophylaxis and treatment of postmenopausal osteoporosis. Finally, since application of external artificial magnetic fields has been shown to synchronize melatonin secretion in experimental animals and humans, we propose that treatment with artificial magnetic fields may be beneficial for postmenopausal osteoporosis.

648

Is the brain influenced by a phone call? An EEG study of resting wakefulness

We recorded the resting electroencephalogram of 20 healthy subjects in order to investigate the effect of electromagnetic field (EMF) exposure on EEG waking activity and its temporal development. The subjects were randomly assigned to two groups and exposed, in double-blind conditions, to a typical mobile phone signal (902.40 MHz, modulated at 217 Hz, with an average power of 0.25 W) before or during the EEG recording session. The results show that, under real exposure as compared to baseline and sham conditions, EEG spectral power was influenced in some bins of the alpha band. This effect was greater when the EMF was on during the EEG recording session than before it. The present data lend further support to the idea that pulsed high-frequency electromagnetic fields can affect normal brain functioning, also if no conclusions can be drawn about the possible health effects.

649

Is the pineal gland involved in the pathogenesis of endometrial carcinoma

The pathogenesis of endometrial carcinoma, which is the most common malignant neoplasm of the female genital tract, is unknown. It is believed that a prolonged period of increased estrogenic exposure unopposed by progesterone may underlie the malignant transformation of the endometrial cells. In the following communication, we propose that deficient melatonin functions may be an additional endocrine factor implicated in the pathogenesis of endometrial carcinoma. This hypothesis is based on the observations that: (a) melatonin has antiestrogenic properties; (b) melatonin stimulates progesterone production which opposes the action of estrogens; (c) an increased rate of endometrial hyperplasia, a premalignant condition, has been noted during the winter, a time of year associated with diminished melatonin secretion; (d) an increased incidence of anovulatory cycles, which is a risk factor for endometrial carcinoma, occurs in the winter; (e) melatonin secretion decreases sharply during the menopause, a period associated with an increased risk of endometrial carcinoma; (f) obesity, which is a major risk factor for endometrial carcinoma, is associated with impaired circadian melatonin secretion; (g) diabetes mellitus, which is an additional risk factor for endometrial carcinoma, is associated with decreased melatonin secretion and an increased rate of pineal calcification; and (h) the prevalence of endometrial carcinoma is lower in the black population compared to the white population. Similarly, the incidence of pineal calcification, which reflects the secretory activity of the gland, is significantly lower in the African and American black populations as compared to the white population.(ABSTRACT TRUNCATED AT 250 WORDS)

650

Issues and design solutions associated with performing MRI scans on patients with active implantable medical devices

Magnetic Resonance Imaging (MRI) has become one of medicine's most important diagnostic tools. However, due to patient safety concerns, MRI is contraindicated by both device and MRI equipment manufacturers for patients with active implanted medical devices (AIMDs). The primary concern is overheating of implanted leadwires due to currents induced from the powerful RF fields of the MRI scanner. In pacemaker patients, heating of myocardial tissue has caused increase in pacemaker capture threshold and in some cases complete loss of capture (inability to pace). Permanent damage to an implantable cardioverter defibrillator and at least one patient death and another with severe burns along the wires of deep brain electrodes have also been reported. The authors, with pacemaker leadwires placed in a "worse case" MRI scan condition, have measured distal tip leadwire temperatures of up to 57 degrees C (more than sufficient to cause tissue damage). Another risk is localized myocardial ablation which could result in changes in the action potential vector during atrial/ventricular contraction. However, in contrast to reports of problems, there have been several recent anecdotal reports of MRI scans being safely performed on non-pacemaker dependent patients under highly controlled conditions. Proper diagnosis, treatment and management of a number of life threatening diseases such as cancer, neurological and brain disorders are made possible by MRI. Accordingly, the physician, with informed patient consent, must sometimes ignore the legal contraindications, weigh the risk factors, and go ahead and perform an MRI on an AIMD patient. This paper quantifies the attendant risks of performing MRI on AIMD patients and discusses means of mitigating certain hazards such as leadwire overheating including the performance a new leadwire distal tip resonant bandstop filter chip (MRI Chip) which presents a high impedance at the MRI pulsed RF frequency.

651

Lack of a correlation between demyelinating plaques on MRI scan and clinical recovery in multiple sclerosis by treatment with electromagnetic fields

A 50 year-old woman presented in January of 1995 with a prolonged history of symptoms of multiple sclerosis (MS) and was classified at the time with a remitting-progressive course. Her chief symptoms included slurring of speech, impairment of vision with intermittent diplopia, difficulties with gait and balance with spastic-ataxic gait, mental depression, insomnia, fatigue, impaired cognitive functions notably poor short term memory and recurrent urinary tract and sinus infections. An MRI scan showed multiple nodular demyelinating lesions scattered in the subcortical white matter and periventricularly of both cerebral hemispheres. Over the following 18 months, while receiving three treatment sessions per week with picotesla electro-magnetic fields (EMFs) which were applied extracranially, she showed a significant recovery in both physical and mental symptoms and additionally experienced decreased susceptibility to infections. In addition, the course of her disease appeared to have stabilized as opposed to the preceding 5 years during which time she experienced insidious, steady deterioration in her functioning. Despite this remarkable clinical recovery through the application of EMFs, and MRI scan obtained at the same diagnostic center 18 months after initiation of treatment with EMFs showed no changes in the number and size of the demyelinating plaques. These findings demonstrate lack of a correlation between recovery of symptoms and the number and extent of demyelinating plaques on MRI scan. It has been known since the days of Charcot in the latter half of the 19th century that in MS there is a great disparity between the histopathological changes of the disease and neurologic deficits. This report enhances the notion that demyelination may reflect an epiphenomenon of the disease.

652

Lack of chromosomal aberration and micronucleus induction in human lymphocytes exposed to pulsed magnetic fields

We exposed human peripheral blood lymphocyte cultures to 50 Hz pulsed magnetic fields (PMFs) in order to evaluate a possible genotoxic effect of such non-ionizing radiation. The genotoxic effect was evaluated in terms of both micronucleus (MN) induction and classical chromosomal aberrations (CA); the mitotic index (MI) was also calculated. Khalil and Qassem (1991) found chromosomal and chromatid breaks and mitotic delay in human lymphocytes exposed for 24, 48 and 72 h to a field with characteristics similar to those used in our laboratory. These data are in contrast with our results previously reported in terms of MN induction using the cytokinesis block method (Scarfi et al., 1991). In this study lymphocytes from five healthy human donors were examined with the above mentioned tests. No genotoxic effects and increased MI were found in exposed samples compared to the control ones, in agreement with our previous results.

653

Lack of effect of weak low frequency electromagnetic fields on chick embryogenesis

Fertilised chicken eggs were incubated for 48 hours while exposed to pulsed trains of square wave magnetic fields having a duration of 0.5 msec and pulse repetition rates of 100 or 1000 Hz at magnetic field flux densities of 1.2 and 12 mu T. After exposure the embryos were scored blind for eight different gross structural features: primary vesicles, anterior neuropore, optic vesicles, auditory pits, truncal nervous system, heart, somites and blood vessels. There were no differences between exposed, sham-exposed and control eggs.

654

Lack of microbial genetic response to 2.45-GHz CW and 8.5- to 9.6-GHz pulsed microwaves

Strain D4 of the yeast Saccharomyces cerevisiae, and strains TA-1535, TA-100 and TA-98 of the bacterium Salmonella typhimurium, were exposed to 2.45-GHz continuous wave or 8.5- to 9.6-GHz pulsed electromagnetic radiation (EMR) at various power densities from 1 to 45 mW/cm2. The temperature during radiation was maintained at 30 degrees C for yeast cultures and at 37 degrees C for bacterial cultures. The studies revealed no increase in mutations or of mitotic gene conversions when cells were radiated for two hours or less. Decreased viability of cells was noted in all cultures tested after radiation at power densities of 30 mW/cm2 or more; however, no reliable changes in genetic events occurred.

655

Lack of mutagenic and co-mutagenic effects of magnetic fields during magnetic resonance imaging

Mutagenic and co-mutagenic effects of static, pulsed bipolar gradient, and high-frequency magnetic fields, as well as combinations of them, were examined using the Ames test. The Ames test using Salmonella typhimurium bacteria, wild-type strain RTA, preincubation assay, without metabolic activation, was performed. All combinations of magnetic fields were tested with and without co-exposure to N-methyl-N'-nitro-N-nitrosoguanidine and benzo[a]pyrene-4,5-oxide, ethylene oxide, carboplatin, or cisplatin. As expected, chemical mutagens caused a clear-cut increase of the revertants in the Ames test. However, neither the static fields nor a combination of a static magnetic field with the time-varying bipolar gradient field or a pulsed high-frequency magnetic field caused an alteration in the number of revertants in the Ames test. No co-mutagenic effect of any magnetic field combination was observed. In conclusion, magnetic fields used during clinical magnetic resonance imaging (MRI) were neither mutagenic nor co-mutagenic.

656

Lack of promotion effects of 50 Hz magnetic fields on 7,12-Dimethylbenz(a)anthracene-induced malignant lymphoma/lymphatic leukemia in mice

New-born CD-1 mice were initiated with a single subcutaneous injection of 60 mg 7,12- dimethylbenz(a)anthracene (DMBA) within 24 h after birth. After weaning, the mice were randomly divided into five groups of 100, 50 males and 50 females each. One group served as a cage control. The other four groups of mice were exposed to either 0 (sham-exposed), 7, 70, or 350 mT(rms) circularly polarized 50 Hz magnetic fields (MFs) for 22 h/day, 7 days/week for 30 weeks. Animals were observed daily and the development of malignant lymphoma/lymphatic leukemia was examined histopathologically. The experiment was conducted twice. There was no observed sexual difference in the cumulative proportions of mice with malignant lymphoma/lymphatic leukemia and a 3-way analysis of deviance using the Cox regression model revealed no interactions between experiment, sex, or group. The cumulative proportions of mice with malignant lymphoma/lymphatic leukemia in the MFexposed groups were not significantly higher than those in the sham-exposed group of each sex in individual experiments and in males and females combined in each experiment, and in all the animals from the two experiments combined. These data provide no evidence to support the hypothesis that power frequency MFs is a significant risk factor for hematopoietic neoplasia. Bioelectromagnetics 29:29–38, 2008.

657

Lagged association between geomagnetic activity and diminished nocturnal papin thresholds in mice.

This study examined 16 minus over a 52 week period of time, correlating nociceptive behavior with changes in geomagnetic activity. They used a hot plate to induce a painful stimulus, monitoring the time it took for mice to respond to increasing temperature. This study observed a weak negative correlation between hotplate pain latency in the geomagnetic activity three days earlier. Reduction in nocturnal pain thresholds in mice follow changes in the Earth's geomagnetic field. The authors conclude that the possibility exists that the occurrence of a geomagnetic storm may cause a decrease in melatonin synthesis and thereby invoking a reduction in pain threshold. In humans, there is evidence that geomagnetic perturbations are associated with a decrease in melatonin released from the pineal gland. Since it is known that melatonin has analgesic effects when administered to mice this association may be important.

658

Laser cooling and magnetic trapping at several tesla

Laser cooling and magnetic trapping of (85)Rb atoms have been performed in extremely strong and tunable magnetic fields, extending these techniques to a new regime and setting the stage for a variety of cold atom and plasma experiments. Using a superconducting Ioffe-Pritchard trap and an optical molasses, 2.4 x 10(7) atoms were laser cooled to the Doppler limit and magnetically trapped at bias fields up to 2.9 T. At magnetic fields up to 6 T, 3 x 10(6) cold atoms were laser cooled in a pulsed loading scheme. These bias fields are well beyond an order of magnitude larger than those in previous experiments. Loading rates, molasses lifetimes, magnetic-trapping times, and temperatures were measured using photoionization and electron detection.

659

Laser-induced fluorescence of Ba+ ions trapped and mass-selected in a Fourier transform ion cyclotron resonance mass spectrometer

We present the design and preliminary results from a Fourier transform ion cyclotron resonance (ICR) mass spectrometer developed for the direct detection of UV/visible laser-induced fluorescence of trapped, mass-selected, gas-phase ions. A 3 T superconducting magnet and an open-ended multi-section cylindrical Penning trap capture and confine ions created by electron impact or laser desorption. Azimuthal quadrupolar excitation in the presence of ion/neutral collisions cools, axializes and mass selects ions as they fill the trap. A pulsed dye laser pumped by an Nd:YAG laser provides electronic energy excitation. A Brewster window and baffles on each side of the vacuum chamber reduce the scattered light from the excitation laser. Laser-induced fluorescence is collected from mirrors and lenses and directed through a quartz window and fiber-optic bundle to a photomultiplier. The ICR and optical events are controlled by a modular ICR data station and GPIB and RS-232 interfaces. An excitation spectrum is demonstrated for atomic Ba+ ions, and should extend to laser-induced fluorescence of virtually any stable positive or negative gas-phase ions of arbitrary molecular weight: molecular or quasimolecular ions, fragment ions, adduct ions, and ions formed from ion/molecule reactions.

660

Leukemic cell intracellular responses to nanosecond electric fields

Intense, nanosecond (ns) pulsed electric fields (PEFs) are known to affect the intracellular structures of cells. The probability of preferentially inducing subcellular effects increases with decreasing pulse length while effects on the plasma membrane are diminished. This has been demonstrated by applying electrical pulses of 60 and 10 ns duration with electric field intensities of up to 6.5 MV/m to HL-60 cells. Using confocal microscopy, PEF-induced changes in the integrity of the plasma membrane and nucleus were measured by recording fluorescence changes with propidium iodide (PI) and acridine orange (AO), respectively. Results suggest that high voltage, nsPEFs target the nucleus and modify cellular functions while plasma membrane effects are delayed and become smaller as pulse duration is shortened. Cell viability was not affected by these pulses. In spite of the high pulsed electric fields, thermal effects can be neglected because of the ultrashort pulse duration. The results suggest application of this ultrashort pulse technology to modulate nuclear structure and function for potential therapeutic benefit.

661

Lifetime of anode polymer in magnetically insulated ion diodes for high-intensity pulsed ion beam generation

Generation of high-intensity pulsed ion beam (HIPIB) has been studied experimentally using polyethylene as the anode polymer in magnetically insulated ion diodes (MIDs) with an external magnetic field. The HIPIB is extracted from the anode plasma produced during the surface discharging process on polyethylene under the electrical and magnetic fields in MIDs, i.e., high-voltage surface breakdown (flashover) with bombardments by electrons. The surface morphology and the microstructure of the anode polymer are characterized using scanning electron microscopy and differential scanning calorimetry, respectively. The surface roughening of the anode polymer results from the explosive release of trapped gases or newly formed gases under the high-voltage discharging, leaving fractured surfaces with bubble formation. The polyethylene in the surface layer degrades into low-molecular-weight polymers such as polyethylene wax and paraffin under the discharging process. Both the surface roughness and the fraction of low molecular polymers apparently increase as the discharging times are prolonged for multipulse HIPIB generation. The changes in the surface morphology and the composition of anode polymer lead to a noticeable decrease in the output of ion beam intensity, i.e., ion current density and diode voltage, accompanied with an increase in instability of the parameters with the prolonged discharge times. The diode voltage (or surface breakdown voltage of polymer) mainly depends on the surface morphology (or roughness) of anode polymers, and the ion current density on the composition of anode polymers, which account for the two stages of anode polymer degradation observed experimentally, i.e., stage I which has a steady decrease of the two parameters and stage II which shows a slow decrease, but with an enhanced fluctuation of the two parameters with increasing pulses of HIPIB generation.

663

Linearly polarized superluminal electromagnetic solitons in cold relativistic plasmas

We investigate a special class of coupled nonlinear superluminal solitons arising from the interaction of an intense linearly polarized electromagnetic pulse with a cold plasma. These modulated envelope structures are obtained as numerical solutions of the classic Akhiezer-Polovin model equations [Sov. Phys. JETP 3, 696 (1956)]. We also present a multiple time scale perturbation analysis in the small amplitude limit that provides a close analytic description of these nonlinear solutions.

664

Local and Holistic Electromagnetic Therapies

Dr. Liboff makes the brilliant assertion that life, at its core, is an electromagnetic entity.Dr. Liboff comments on the use of the ion cyclotron resonance (Seqex) device as an innovative way to apply Pulsating electromagnetic field therapy for holistic health, rather than just for focal dysfunction of bone or connective tissue.

665

Local cooling for relieving pain from perineal trauma sustained during childbirth

BACKGROUND: Perineal trauma is common during childbirth and may be painful. Contemporary maternity practice includes offering women numerous forms of pain relief, including the local application of cooling treatments. OBJECTIVES: To evaluate the effectiveness and side effects of localised cooling treatments compared with no treatment, other forms of cooling treatments and non-cooling treatments. SEARCH STRATEGY: We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (January 2007), CINAHL (1982 to January 2007) and contacted experts in the field. SELECTION CRITERIA: Published and unpublished randomised and quasi-randomised trials (RCTs) that compared localised cooling treatment applied to the perineum with no treatment or other treatments applied to relieve pain related to perineal trauma sustained during childbirth. DATA COLLECTION AND ANALYSIS: At least two independent authors performed data extraction for each study. Analyses were performed on an intention-to-treat basis where data allowed. We sought additional information from the authors of three trials. MAIN RESULTS: Seven published RCTs were included, comparing local cooling treatments (ice packs, cold gel pads or cold/iced baths) with no treatment, hamamelis water (witch hazel), pulsed electromagnetic energy (PET), hydrocortisone/pramoxine foam [Epifoam] or warm baths. The RCTs reported on a total of 859 women. Ice packs provided improved pain relief 24 to 72 hours after birth compared with no treatment (risk ratio (RR) 0.61, 95% confidence interval (CI) 0.41 to 0.91). Women preferred the utility of the gel pads compared with ice packs or no treatment, although no differences in pain relief were detected between the treatments. None of our comparisons of treatments resulted in differences detected in perineal oedema or bruising. Women reported more pain (RR 5.60, 95% CI 2.35 to 13.33) and used more additional analgesia (RR 4.00, 95% CI 1.44 to 11.13) following the application of ice packs compared with PET. AUTHORS' CONCLUSIONS: There is only limited evidence to support the effectiveness of local cooling treatments (ice packs, cold gel pads, cold/iced baths) applied to the perineum following childbirth to relieve pain.

666

Local observation of reverse-domain superconductivity in a superconductor-ferromagnet hybrid

Nanoscale magnetic and superconducting properties of the superconductor-ferromagnet Nb/PbFe12O19 hybrid were studied as a function of applied magnetic fields. Low-temperature scanning laser microscopy (LTSLM) together with transport measurements were carried out in order to reveal local variations of superconductivity induced by the magnetic field template produced by the ferromagnetic substrate. Room temperature magnetic force microscopy (MFM) was performed and magnetization curves were taken at room and low temperature to investigate the magnetic properties of the hybrid. Comparative analysis of the LTSLM and the MFM images has convincingly demonstrated the presence of the reverse-domain superconductivity.

667

Local spectrum analysis of field propagation in an anisotropic medium. Part II. Time-dependent fields

In Part I of this two-part investigation [J. Opt. Soc. Am. A 22, 1200 (2005)], we presented a theory for phase-space propagation of time-harmonic electromagnetic fields in an anisotropic medium characterized by a generic wave-number profile. In this Part II, these investigations are extended to transient fields, setting a general analytical framework for local analysis and modeling of radiation from time-dependent extended-source distributions. In this formulation the field is expressed as a superposition of pulsed-beam propagators that emanate from all space-time points in the source domain and in all directions. Using time-dependent quadratic-Lorentzian windows, we represent the field by a phase-space spectral distribution in which the propagating elements are pulsed beams, which are formulated by a transient plane-wave spectrum over the extended-source plane. By applying saddle-point asymptotics, we extract the beam phenomenology in the anisotropic environment resulting from short-pulsed processing. Finally, the general results are applied to the special case of uniaxial crystal and compared with a reference solution.

668

Localized pulsed magnetic fields for tendonitis therapy

Energy medicine has existed for centuries in some parts of the world, but in recent years, western health care practitioners have taken a heightened interest in these therapies. Treatment by use of pulsed magnetic fields (PMF) is currently being explored in both chronic and inflammatory diseases such as cancer, epilepsy, psoriasis, rheumatoid arthritis, and tendinitis. In the U.S., PMFs have already been approved for use in treatment of bone fractures in humans and clinical trials have been conducted for lower back pain. This study presents a summary of the therapeutic potential of a localized PMF treatment for tendinitis using the Softpulse III system. This system has been used to accelerate wound healing and soft tissue swelling. It generates a specific PMF that induces an electrical field within the tendon. This induced electrical field is thought to influence the healing process by affecting the inflammatory cells that line the tendon sheath. In this study, we have used an established model of tendinitis along with a validated method for appraising edema and gait (Achilles' Functional Index), to test the hypothesis that the proposed PMF signal is effective in reducing the indicators of acute tendinitis injury. These experiments were approved by the Institutional Animal Care and Use Committee. Our findings suggest a role for the treatment of soft tissue injury using the Softpulse III therapeutic device. The symbolic stand point of PMF treatments is to push the need for a revolutionary leap, from the more dominant pharmaceutical and surgical interventions, to the advanced applications of non-invasive therapies that would minimize the medicinal risk of side effects, and eliminate the risk of complicated drug interactions.

669

Long term beneficial effects of weak electromagnetic fields in multiple sclerosis

A 39 year-old severely disabled woman with a 19 year history of chronic relapsing-remitting multiple sclerosis (MS) began to experience improvement in symptoms within 24 hours after she received experimental treatment with picotesla electromagnetic fields (EMFs). Pattern reversal visual evoked potential (VEP) study obtained three weeks after the initiation of the first magnetic treatment showed a return to normal of the P100 latencies in each eye. The patient continued to receive 1-2 EMFs treatments per week and during the following 32 months she made a dramatic recovery with resolution of diplopia, blurring of vision, dysarthria, ataxia of gait, and bladder dysfunction as well as improvement in fatigue, heat tolerance, mood, sleep, libido, and cognitive functions. VEP studies, which were repeated in April of 1995 more than 2 1/2 years after the initiation of magnetic treatment, showed that P100 latencies remained normal in each eye providing objective documentation that continued application of these EMFs may sustain normal conduction in the damaged optic pathways over a long period of time. This is the first case report documenting the dramatic long term beneficial effects of treatment with picotesla range EMFs in a patient with MS.

670

Long-lasting plasma membrane permeabilization in mammalian cells by nanosecond pulsed electric field (nsPEF)

The barrier function of plasma membrane in nsPEF-exposed mammalian cells was examined using whole-cell patch-clamp techniques. A specialized setup for nsPEF exposure of individual cells in culture was developed and characterized for artifact-free compatibility with the patch-clamp method. For the first time, our study provides experimental evidence that even a single 60-ns pulse at 12 kV/cm can cause a profound and long-lasting (minutes) reduction of the cell membrane resistance (R(m)), accompanied by the loss of the membrane potential. R(m) measured in GH3, PC-12, and Jurkat cells (but not in HeLa cells) in 80-120 s after nsPEF exposure was decreased about threefold, and its gradual recovery could take 15 min. Multiple pulses enhanced permeabilization, for example, R(m) in GH3 cells fell about 10-fold after a train of five pulses. Within studied limits, permeabilization did not depend on the presence of Ca(2+), Mg(2+), K(+), Cs(+), Cd(2+), EGTA, tetraethylammonium, or 4-aminopyridine in the pipette or bath solutions. Our results supported theoretical model predictions of plasma membrane poration by nsPEF. However, the extended decrease in R(m), assumed to be related to the life span of the pores, and different nsPEF sensitivity of individual cell lines have yet to be explained. The phenomenon of long-lived membrane permeabilization provides new insights on the nature of nsPEF-opened conductance pores and on molecular mechanisms that underlie nsPEF bioeffects.

671

Long-term beneficial effects of week in electomagnetic fields in multiple sclerosis

This case report documents a dramatic long-term benefit in a 39-year-old severely disabled woman with a 19 year history of chronic relapsing remitting multiple sclerosis. (I have abstract only.)

672

Long-term consequences of subtle stimuli during the first twenty-four hours of seizure-induced brain injury

Chronically epileptic (induced by a single systemic injection of lithium and pilocarpine about 30 days before the experiment began) male rats were trained within a radial maze while they were administered either GABA-pentin (Neurontin), or prednisolone or given no treatment. There was no significant improvement in learning or memory between the groups. Numbers of trials per day were positively correlated with the time required to display the overt stereotyped forelimb clonus after the single pilocarpine injection. The numbers of correct trials completed during the first few days of acquisition were significantly greater for the rats that had receive weak (1 microT) complex, pulsed magnetic fields over the right hemisphere during the first 24 hr. after seizure induction than for those who received the same field over the left hemisphere or that had been exposed to reference conditions. Implications of the enhanced sensitivity of limbic neurons to subtle electromagnetic interaction during electrical lability are discussed.

673

Long-term follow-up of fracture nonunions treated with PEMFs

One hundred thirty-nine established fracture nonunions were treated using a pulsed electromagnetic field (PEMF) device that also recorded patient usage. Patients who used the device less than an average of three hours a day had a success rate of 35.7% (5/14), while those who used the device in excess of three hours daily had an 80% success rate (108/135). The difference in the success rate was statistically significant at p less than .05. Treatment success was unaffected by long versus short bone, open versus closed fractures, nonunion of nine to 12 months duration compared to one to ten years, age of patient (whether less than or greater than age 60), gender, recalcitrant versus first time treatment, infected versus noninfected nonunions, fracture gaps up to 1cm, or weightbearing versus nonweightbearing. Ninety-seven fractures in 90 patients (90% follow-up) who averaged more than three hours of PEMF treatment daily and were originally classified as healed were reevaluated clinically and radiographically at four years following treatment (range: 3.6-5.4 years; mean: 4.1 years). Eighty-nine (92%) maintained a solid union. The success rate of PEMF treatment for nonunion repair demonstrated no statistically significant change over long-term follow-up.

674

Long-term pulsed electromagnetic field (PEMF) results in congenital pseudarthrosis

Ninety-one patients with congenital pseudarthrosis of the tibia have been treated with pulsed electromagnetic fields (PEMFs) since 1973 and all except 4 followed to puberty. Lesions were stratified by roentgenographic appearance. Type I and type II had gaps less than 5 mm in width. Type III were atrophic, spindled, and had gaps in excess of 5 mm. Overall success in type I and II lesions was 43 of 60 (72%). Of those 28 patients seen before operative repair had been attempted, 7 of 8 type I lesions healed (88%), whereas 16 of 20 type II lesions healed (80%) on PEMFs and immobilization alone. Only 19% (6 of 31) type III lesions united, only one of which did not require surgery. Sixteen of 91 limbs (18%) were ultimately amputed, most before treatment principles were fully defined in 1980. Fourteen of these 16 patients (88%) had type III lesions. Refracture occurred in 22 patients, most as the result of significant trauma, in the absence of external brace support. Twelve of the 19 refractures, retreated with PEMFs and casts, healed on this regime. Episodic use of PEMFs proved effective in controlling stress fractures in several patients until they reached puberty. PEMFs, which are associated with no known risk, appear to be an effective, conservative adjunct in the management of this therapeutically challenging, congenital lesions.

675

Loss of interstitial cells of Cajal after pulsating electromagnetic field (PEMF) in gastrointestinal tract of the rats

Exposure to the magnetic field has remarkably increased lately due to fast urbanization and widely available magnetic field in diagnosis and treatment. However, biological effects of the magnetic field are not well recognized. The myoelectric activity recorded from the gastrointestinal and urinary systems is generated by specialized electrically active cells called interstitial cells of Cajal (ICCs). Thus it seems rational that ICC have significant vulnerability to physical factors like an electromagnetic field. The aim of this study was to evaluate the influence of pulsating electromagnetic field (PEMF) (frequency 10 kHz, 30ms, 300 muT burst, with frequency 1Hz) on ICCs density in the rat gastrointestinal tract. Rats were divided into two groups (n=32). The first group was exposed to PEMF continuously for 1, 2, 3, and 4 weeks (n = 16), and the second group (n=16) served as a control. Tissue samples of the rat stomach, duodenum and proximal colon were fixed and paraffin embedded. The tangential sections of 5 microm thickness were stained immunohistochemically with anti-c-Kit (sc-168) antibody and visualized finally by DAB as chromogen (brown end product). C-Kit positive branched ICC-like cells were detected under the light microscope, distinguished from the c-kit-negative non-branched smooth muscle cells and from the c-kit positive but non-branched mast cells and quantitatively analyzed by MultiScan computer program. Apoptosis detection was performed with rabbit anti-Bax polyclonal antibody (Calbiochem, Germany) and LSAB 2 visualization system. The surface of c-Kit immunopositive cells decreased after exposure to PEMF in each part of the gastrointestinal tract. Reduced density of ICCs was related to exposure time. The most sensitive to PEMF were ICCs in the fundus of the stomach and in the duodenum, less sensitive were ICCs in the colon and pacemaker areas of the stomach. No marked changes in ICC density in the pyloric part of the stomach were observed. We demonstrate that the PEMF induced apoptosis dependent decrease in ICC expression.

676

Low energy pulsing electromagnetic fields modify biomedical processes

Low-energy, pulsed electromagnetic fields (PEMFs) have reversed therapeutically resistant pathologic processes in the musculo-skeletal system. Their development as a non-thermal therapeutic agent is based on 30 years of study of the electro-biological properties of connective tissues. Specific energy characteristics in applied PEMFs produce selected biological effects by modifying synthetic and other behavioral patterns of target cells; some mechanisms of action are defined. The technology appears safe and effective in clinical treatment of un-united fractures, avascular necrosis of bone, and chronic, refractory tendinitis. An expanding, rational use in biomedical science is predicted.

677

Low frequency and low intensity pulsed electromagnetic field exerts its antiinflammatory effect through restoration of plasma membrane calcium ATPase activity

Rheumatoid arthritis (RA) is a chronic inflammatory disorder affecting 1% of the population worldwide. Pulsed electromagnetic field (PEMF) has a number of well-documented physiological effects on cells and tissues including antiinflammatory effect. This study aims to explore the antiinflammatory effect of PEMF and its possible mechanism of action in amelioration of adjuvant induced arthritis (AIA). Arthritis was induced by a single intradermal injection of heat killed Mycobacterium tuberculosis at a concentration of 500 microg in 0.1 ml of paraffin oil into the right hind paw of rats. The arthritic animals showed a biphasic response regarding changes in the paw edema volume. During the chronic phase of the disease, arthritic animals showed an elevated level of lipid peroxides and depletion of antioxidant enzymes with significant radiological and histological changes. Besides, plasma membrane Ca(2+) ATPase (PMCA) activity was inhibited while intracellular Ca(2+) level as well as prostaglandin E(2) levels was noticed to be elevated in blood lymphocytes of arthritic rats. Exposure of arthritic rats to PEMF at 5 Hzx4 microT x 90 min, produced significant antiexudative effect resulting in the restoration of the altered parameters. The antiinflammatory effect could be partially mediated through the stabilizing action of PEMF on membranes as reflected by the restoration of PMCA and intracellular Ca(2+) levels in blood lymphocytes subsequently inhibiting PGE(2) biosynthesis. The results of this study indicated that PEMF could be developed as a potential therapy for RA in human beings.

678

Low frequency electromagnetic radiation and hearing

Objective:To analyse the possible impact of low and extremely low frequency electromagnetic fields on the outer hairs cells of the organ of Corti, in a guinea pig model.Materials and methods:Electromagnetic fields of 50, 500, 1000, 2000, 4000 and 5000 Hz frequencies and 1.5 microT intensity were generated using a transverse electromagnetic wave guide. Guinea pigs of both sexes, weighing 100-150 g, were used, with no abnormalities on general and otic examination. Total exposure times were: 360 hours for 50, 500 and 1000 Hz; 3300 hours for 2000 Hz; 4820 hours for 4000 Hz; and 6420 hours for 5000 Hz. One control animal was used in each frequency group. The parameters measured by electric response audiometer included: hearing level; waves I-IV latencies; wave I-III interpeak latency; and percentage appearance of waves I-III at 90 and 50 dB sound pressure level intensity.Results:Values for the above parameters did not differ significantly, comparing the control animal and the rest of each group. In addition, no significant differences were found between our findings and those of previous studies of normal guinea pigs.Conclusion:Prolonged exposure to electromagnetic fields of 50 Hz to 5 KHz frequencies and 1.5 microT intensity, produced no functional or morphological alteration in the outer hair cells of the guinea pig organ of Corti.

679

Low frequency EMF regulates chondrocyte differentiation and expression of matrix proteins

This study describes the enhancement of chondrogenic differentiation in endochondral ossification by extremely low frequency pulsed electric/magnetic fields (EMFs). The demineralized bone matrix (DBM)-induced endochondral ossification model was used to examine the effects of EMF stimulation. [35S]-Sulfate and [3H]-thymidine incorporation and glycosaminoglycan (GAG) content were determined by standard methods. Proteoglycan (PG) and GAG molecular size and composition were determined by gel chromatography and sequential enzyme digestion. Immunohistochemical and Western blot analysis of PGs were done with antibodies 2B6, 3B3, 2D3 and 5D4. Northern analysis of total RNA extracts was performed for aggrecan, and type II collagen. All data was compared for significance by Student's t- or analysis of variance (ANOVA)-tests. The EMF field accelerated chondrogenesis as evidenced by an increase in: (1) 35SO4 incorporation and GAG content, (2) the number of chondrocytes at day 8 of development, (3) the volumetric density of cartilage and (4) the extent of immunostaining for 3B3 and 5D4. No differences in DNA content or [3H]-thymidine incorporation were observed between control and stimulated ossicles, suggesting the absence of enhanced cell proliferation or recruitment as a mechanism for the acceleration. PG and GAG molecular sizes and GAG chemical composition were similar in stimulated and control ossicles, indicating that stimulation resulted in an accelerated synthesis of normal cartilage molecules. The increased expression of PG and type II collagen mRNA as well as a greater immunoreactivity of 3B3 and 5D4 suggest an increase in the rate of differentiation of chondrocytes and enhanced phenotypic maturation.

680

Low frequency magnetic emissions and resulting induced voltages in a pacemaker by iPod portable music players

BACKGROUND: Recently, malfunctioning of a cardiac pacemaker electromagnetic, caused by electromagnetic interference (EMI) by fields emitted by personal portable music players was highly publicized around the world. A clinical study of one patient was performed and two types of interference were observed when the clinicians placed a pacemaker programming head and an iPod were placed adjacent to the patient's implanted pacemaker. The authors concluded that "Warning labels may be needed to avoid close contact between pacemakers and iPods". We performed an in-vitro study to evaluate these claims of EMI and present our findings of no-effects" in this paper. METHODS: We performed in-vitro evaluations of the low frequency magnetic field emissions from various models of the Apple Inc. iPod music player. We measured magnetic field emissions with a 3-coil sensor (diameter of 3.5 cm) placed within 1 cm of the surface of the player. Highly localized fields were observed (only existing in a one square cm area). We also measured the voltages induced inside an 'instrumented-can' pacemaker with two standard unipolar leads. Each iPod was placed in the air, 2.7 cm above the pacemaker case. The pacemaker case and leads were placed in a saline filled torso simulator per pacemaker electromagnetic compatibility standard ANSI/AAMI PC69:2000. Voltages inside the can were measured. RESULTS: Emissions were strongest ( approximately 0.2 muT pp) near a few localized points on the cases of the two iPods with hard drives. Emissions consisted of 100 kHz sinusoidal signal with lower frequency (20 msec wide) pulsed amplitude modulation. Voltages induced in the iPods were below the noise level of our instruments (0.5 mV pp in the 0 - 1 kHz band or 2 mV pp in the 0 - 5 MHz bandwidth. CONCLUSION: Our measurements of the magnitude and the spatial distribution of low frequency magnetic flux density emissions by 4 different models of iPod portable music players. Levels of less than 0.2 muT exist very close (1 cm) from the case. The measured voltages induced inside an 'instrumented-can' pacemaker were below the noise level of our instruments. Based on the observations of our in-vitro study we conclude that no interference effects can occur in pacemakers exposed to the iPod devices we tested.

681

Low frequency NMR polarimeter for hyperpolarized gases

An inexpensive and self-contained apparatus for pulsed NMR at 30-250 kHz is described. The intended application is monitoring of the spin polarization of rare gas nuclei in a laser-polarizing apparatus in fields of order 30 G. In addition, the device provides a convenient method for following the polarization decay during storage and transport. Some of the features are a flexible pulse generator, splitting of transmitter RF cycles by the RF gate, a Q switch, and a wide range of receiver gains.

682

Low frequency therapeutic EMF differently influences experimental muscle pain in female and male subjects

Effects of a pulsating, half sine wave magnetic field (MF) with a frequency of 100 pps and 15 mT rms flux density, generated by the MD TEMF device (EMF Therapeutics, Inc., Chattanooga), on subjective pain rating, heart rate, and arterial blood pressure were tested in a double blind, crossover design study employing experimental muscle pain. Each of 24 healthy volunteers (12 females and 12 males, 24.7 +/- 3.2 years of age) received painful stimulation induced by the infusion of 5% hypertonic saline (HS) into the erector spinae muscle during real and sham MF exposure, in counterbalanced order. Exposure to MF differently affects subjective pain estimates in females and males. MF exposure increased averaged pain level and time integral of pain ratings in females, whereas no statistically significant difference for these characteristics was found in males. Pain related elevation of systolic and diastolic blood pressure was observed during both real and sham EMF exposure in female and male subjects.

683

Low magnetic field effects on embryonic bone growth

Pulsed electromagnetic fields [EMF] and electric fields have been demonstrated to promote osteogenesis and wound healing. Pulsed EMF's have been approved since 1979 by the FDA, and are highly effective in the treatment of non-union fractures. Increased linear growth, cellular proliferation, cAMP and uptake of tritiated thymidine have been documented on short term exposure. Yet the mechanisms and the changes that occur have been difficult to quantify. Fluorescence, light, and electron microscopy were utilized in this study to assess any histological changes in bone. During incubation chick embryos were exposed to magnets oriented in various positions. Controls were oriented similarly using galvanized steel plugs. Field density in the center of the field was measure by a gaussmeter with a transverse probe. Each chick embryo in its magnetic field was isolated from the magnetic fields of others by being encased in a steel box. Intramembranous [calvaria] and endochondral [tibia] ossification were studied. Fluorescent dyes were micropipetted intravascularly at various stages of chick development. The tissues were fixed in methacrylate and stained for histomorphological study.

684

Low magnetic fields for flow propagators in permeable rocks

Pulsed field gradient NMR flow propagators for water flow in Bentheimer sandstone are measured at low fields (1H resonance 2 MHz), using both unipolar and bipolar variants of the pulsed gradient method. We compare with propagators measured at high fields (1H resonance 85 MHz). We show that (i) measured flow propagators appear to be equivalent, in this rock, and (ii) the lower signal to noise ratio at low fields is not a serious limitation. By comparing different pulse sequences, we study the effects of the internal gradients on the propagator measurement at 2 MHz, which for certain rocks may persist even at low fields.

685

Low resolution electromagnetic tomography analysis of ictal EEG patterns in mesial temporal lobe epilepsy with hippocampal sclerosis

OBJECTIVE: To investigate the difference in the spatial distribution of scalp initial ictal discharge (IID) patterns in mesial temporal lobe epilepsy with hippocampal sclerosis (HS-MTLE). METHODS: Scalp ictal EEG data in 22 seizure-free patients after temporal lobectomy with amygdalo-hippocampectomy were classified as follows: a regular 5-9Hz rhythm with a restricted temporal/subtemporal distribution (type 1, 11 patients), or an irregular 2-5Hz rhythm with a widespread fronto-temporal distribution (type 2, 11 patients). EEG data were fragmented into segments of 1.28s, both at ictal onset and at baseline. The LORETA solution of three frequency bands was compared between ictal and baseline using statistical non-parametric mapping (p<0.01). RESULTS: The LORETA solution of 5-9Hz in type 2 had wider cortical activity in the ipsilateral fronto-temporal area, compared to type 1 with activation of the ipsilateral focal mesial and lateral temporal regions. The LORETA solution of 10-13Hz in both types showed increased activity in the fronto-temporal area, which was wider in type 2 than type 1. Increased cortical activity of <5Hz was not observed in type 1, whereas increased cortical activity was observed in the bilateral anterior frontal area in type 2. CONCLUSIONS: The cortical source distribution in HS-MTLE may depend on scalp IID frequency. The neural generators of 5-13Hz may be important for the formation of the ictal onset zone in both ictal patterns. SIGNIFICANCE: Spatial distributions in HS-MTLE patients differ with scalp IID frequency.

686

Low-amplitude, extremely low frequency magnetic fields for the treatment of osteoarthritic knees: a double-blind clinical study.

CONTEXT: Noninvasive magnetotherapeutic approaches to bone healing have been successful in past clinical studies. OBJECTIVE: To determine the effectiveness of low-amplitude, extremely low frequency magnetic fields on patients with knee pain due to osteoarthritis. DESIGN: Placebo-controlled, randomized, double-blind clinical study. SETTING: 4 outpatient clinics. PARTICIPANTS: 176 patients were randomly assigned to 1 of 2 groups, the placebo group (magnet off) or the active group (magnet on). INTERVENTION: 6-minute exposure to each magnetic field signal using 8 exposure sessions for each treatment session, the number of treatment sessions totaling 8 during a 2-week period, yielded patients being exposed to uniform magnetic fields for 48 minutes per treatment session 8 times in 2 weeks. The magnetic fields used in this study were generated by a Jacobson Resonator, which consists of two 18-inch diameter (46-cm diameter) coils connected in series, in turn connected to a function generator via an attenuator to obtain the specific amplitude and frequency. The range of magnetic field amplitudes used was from 2.74 x 10(-7) to 3.4 x 10(-8) G, with corresponding frequencies of 7.7 to 0.976 Hz. OUTCOME MEASURES: Each subject rated his or her pain level from 1 (minimal) to 10 (maximal) before and after each treatment and 2 weeks after treatment. Subjects also recorded their pain intensity in a diary while outside the treatment environment for 2 weeks after the last treatment session (session 8) twice daily: upon awakening (within 15 minutes) and upon retiring (just before going to bed at night). RESULTS: Reduction in pain after a treatment session was significantly (P < .001) greater in the magnet-on group (46%) compared to the magnet-off group (8%). CONCLUSION: Low-amplitude, extremely low frequency magnetic fields are safe and effective for treating patients with chronic knee pain due to osteoarthritis.

687

Low-field magnetic stimulation in bipolar depression using an MRI-based stimulator

OBJECTIVE: Anecdotal reports have suggested mood improvement in patients with bipolar disorder immediately after they underwent an echo-planar magnetic resonance spectroscopic imaging (EP-MRSI) procedure that can be performed within clinical MR system limits. This study evaluated possible mood improvement associated with this procedure. METHOD: The mood states of subjects in an ongoing EP-MRSI study of bipolar disorder were assessed by using the Brief Affect Scale, a structured mood rating scale, immediately before and after an EP-MRSI session. Sham EP-MRSI was administered to a comparison group of subjects with bipolar disorder, and actual EP-MRSI was administered to a comparison group of healthy subjects. The characteristics of the electric fields generated by the EP-MRSI scan were analyzed. RESULTS: Mood improvement was reported by 23 of 30 bipolar disorder subjects who received the actual EP-MRSI examination, by three of 10 bipolar disorder subjects who received sham EP-MRSI, and by four of 14 healthy comparison subjects who received actual EP-MRSI. Significant differences in mood improvement were found between the bipolar disorder subjects who received actual EP-MRSI and those who received sham EP-MRSI, and, among subjects who received actual EP-MRSI, between the healthy subjects and the bipolar disorder subjects and to a lesser extent between the unmedicated bipolar disorder subjects and the bipolar disorder subjects who were taking medication. The electric fields generated by the EP-MRSI scan were smaller (0.7 V/m) than fields used in repetitive transcranial magnetic stimulation (rTMS) treatment of depression (1-500 V/m) and also extended uniformly throughout the head, unlike the highly nonuniform fields used in rTMS. The EP-MRSI waveform, a 1-kHz train of monophasic trapezoidal gradient pulses, differed from that used in rTMS. CONCLUSIONS: These preliminary data suggest that the EP-MRSI scan induces electric fields that are associated with reported mood improvement in subjects with bipolar disorder. The findings are similar to those for rTMS depression treatments, although the waveform used in EP-MRSI differs from that used in rTMS. Further investigation of the mechanism of EP-MRSI is warranted.

688

Low-frequency pulsed electromagnetic field exposure can alter neuroprocessing in humans

Extremely low-frequency magnetic fields (from DC to 300 Hz) have been shown to affect pain sensitivity in snails, rodents and humans. Here, a functional magnetic resonance imaging study demonstrates how the neuromodulation effect of these magnetic fields influences the processing of acute thermal pain in normal volunteers. Significant interactions were found between pre- and post-exposure activation between the sham and exposed groups for the ipsilateral (right) insula, anterior cingulate and bilateral hippocampus/caudate areas. These results show, for the first time, that the neuromodulation induced by exposure to low-intensity low-frequency magnetic fields can be observed in humans using functional brain imaging and that the detection mechanism for these effects may be different from those used by animals for orientation and navigation. Magnetoreception may be more common than presently thought.

689

Low-intensity pulsed ultrasound and pulsed electromagnetic field in the treatment of tibial fractures: a systematic review

OBJECTIVE: To compare the effects of low-intensity pulsed ultrasound (LIPUS) or pulsed electromagnetic fields (PEMF) on fracture healing through a systematic review of original, English-language clinical research reports. DATA SOURCES: A search of MEDLINE, Physiotherapy Evidence Database (PEDro), and ProQuest to identify clinical trials of LIPUS or PEMF with fractures in humans, written in English, published from 1966 through 2004. Key words were ultrasound, fracture, tibial, electric current, and healing. STUDY SELECTION: After search limits were applied, 17 papers were assessed independently by 2 reviewers. Papers were excluded from consideration if they lacked (1) random allocation of treatments, (2) inclusion of skeletally mature patients of either sex with a current fracture, (3) blinding of both the patient and the assessors as to treatment group, (4) administration of either LIPUS or PEMF treatments to one of the treatment groups, or (5) assessment of time to fracture healing or proportion of fractures healed, as determined radiographically, clinically, or both. DATA EXTRACTION: Eight trials met the inclusion criteria. Methodologic quality of all trials was assessed using the PEDro criteria. Outcome measures were tabulated. DATA SYNTHESIS: Heterogeneity among studies precluded direct comparison of the efficacy of LIPUS to that of PEMF. CONCLUSIONS: The studies we included in our review were of generally high methodologic quality. The evidence suggests that LIPUS may speed healing of acute tibial fractures. Comparison studies of these modalities are needed to guide treatment of fractures sustained by athletic individuals.

690

Low-threshold two-dimensional annular Bragg lasers

Lasing at telecommunication wavelengths from annular resonators employing radial Bragg reflectors is demonstrated at room temperature under pulsed optical pumping. Submilliwatt pump threshold levels are observed for resonators with 0.5-1.5-wavelength-wide defects of radii 7-8 microm. The quality factors of the resonator modal fields are estimated to be of the order of a few thousand. The electromagnetic field is shown to be guided by the defect. Good agreement is found between the measured and the calculated spectra.

691

Lung cancer in relation to employment in the electrical utility industry and exposure to magnetic fields

OBJECTIVES: A recent study found that lung cancer may be associated with exposures encountered in the electrical utility industry. To further evaluate this possibility, data were collected and analysed from five large electrical utility companies in the United States. METHODS: A cohort of 138905 male workers employed between 1950 and 1986 was followed up for mortality to the end of 1988, with 20733 deaths identified of which 1692 were due to lung cancer. Mortality from lung cancer was examined in relation to the duration of employment in specific jobs thought to have high exposure to 60 Hz magnetic fields and to an index of cumulative exposure to magnetic fields based on personal measurements. Exposure to pulsed electromagnetic fields (PEMFs) as estimated from another study was also considered. Poisson regression generated rate ratios for categories of exposure based on comparisons within the cohort adjusted for age, calendar year, race, socioeconomic status, work status, and estimated exposure to asbestos. RESULTS: Mortality rose modestly with duration of work as an electrician or power plant operator reaching rate ratios of 1.4 with > or = 20 years in those jobs but not with duration of work as a lineman or a combination of jobs thought to have high exposures to 60 Hz magnetic fields or PEMFs. Cumulative indices of exposure to 60 Hz magnetic fields and PEMFs were both associated with rate ratios of 1.2-1.3 in the highest intervals. CONCLUSIONS: These data suggest that lung cancer is not strongly associated with duration of employment in specific jobs associated with high potential exposure to 60 Hz magnetic fields or to PEMFs. Small associations of lung cancer with indices of both 60 Hz magnetic fields and PEMFs leave open the possibility that larger associations have been diluted through exposure misclassification. Refined exposure assessment, especially to PEMFs, would be required to evaluate that possibility.

692

Lymphoma development among mice exposed to X-rays and pulsed magnetic fields

CBA mice were exposed to a total of 5.24 Gy X-rays (260 kV, 11 mA, 0.45 Gy/min), divided into four exposures, and to saw-tooth 15 microT (peak to peak) pulsed vertical 200 kHz magnetic fields for their life-time. In parallel, series with magnetic fields only or non-exposed animals were run. The animals were observed for their life-time. The frequency of lymphomas was 65.7% in the X-ray group and 71.4% in the groups exposed to both X-ray and magnetic field. Of the non-exposed control animals, and of the animals exposed to magnetic fields only 6.4 and 5.7% had lymphomas, respectively. There were no statistically significant differences between the magnetic field series and the corresponding controls for lymphomas. Blood cell counts and haemoglobin data did not show differences between the X-irradiated, and X-ray and magnetic field-exposed groups. Mononuclear cells and total leukocytes were elevated for pulsed magnetic fields-exposed animals compared with the non-exposed controls. This difference was due to two animals with extreme values. In the pulsed magnetic fields treated group there was a statistically significant increase of the carcass weight compared with the non-treated control group.

693

Lymphomas in E mu-Pim1 transgenic mice exposed to pulsed 900 MHZ electromagnetic fields

Whether radiofrequency (RF) fields are carcinogenic is controversial; epidemiological data have been inconclusive and animal tests limited. The aim of the present study was to determine whether long-term exposure to pulse-modulated RF fields similar to those used in digital mobile telecommunications would increase the incidence of lymphoma in E mu-Pim1 transgenic mice, which are moderately predisposed to develop lymphoma spontaneously. One hundred female E mu-Pim1 mice were sham-exposed and 101 were exposed for two 30-min periods per day for up to 18 months to plane-wave fields of 900 MHz with a pulse repetition frequency of 217 Hz and a pulse width of 0.6 ms. Incident power densities were 2.6-13 W/m2 and specific absorption rates were 0.008-4.2 W/kg, averaging 0.13-1.4 W/kg. Lymphoma risk was found to be significantly higher in the exposed mice than in the controls (OR = 2.4. P = 0.006, 95% CI = 1.3-4.5). Follicular lymphomas were the major contributor to the increased tumor incidence. Thus long-term intermittent exposure to RF fields can enhance the probability that mice carrying a lymphomagenic oncogene will develop lymphomas. We suggest that such genetically cancer-prone mice provide an experimental system for more detailed assessment of dose-response relationships for risk of cancer after RF-field exposure.

694

Magnetic and electric characteristics of the electric fish Gymnotus carapo

The fresh water fish Gymnotus carapo produces a continuous series of weak pulsed electric fields in its surroundings and senses disturbances of this field as part of its sensory system. The electric and magnetic properties of the electric organ of this fish were studied. Magnetic fields close to the fish on the order of nT are produced by currents on the order of 10(-4) A in the electric organ of the fish. The electromotive force, the internal resistance, the current, and the electric power of the equivalent circuit were determined noninvasively.

696

Magnetic and electrical stimulation in the rehabilitative treatment of patients with organic lesions of the nervous system

Studies were performed on 89 patients with organic lesions of the nervous system in which the leading clinical symptoms consisted of paralysis and pareses. Patients received complex treatment, including pulsed magnetic fields and an electrical stimulation regime producing multilevel stimulation. A control group of 49 patients with similar conditions was included, and these patients received only sinusoidal currents. Combined treatment with magnetic and electrical stimulation was more effective, as indicated by radiographic and electromyographic investigations.

697

Magnetic birefringence of minerals

The earliest reports of magnetically induced optical birefringence included data for liquids, magnetic fluids and colloidal suspensions. Recent work has shown that with relatively straightforward apparatus, when carefully designed and aligned, measurable effects can be recorded even for suspensions of relatively weak diamagnetic materials, including mineral particles. By recording the magnitude of the birefringence induced in magnetic fields of up to two Tesla, a method for the analysis of the magnetic and optical characteristics of these diamagnetic colloids is evidenced. The principles, apparatus and methodology involved are described and novel data reported for the minerals attapulgite, bentonite, hectorite, kaolinite, montmorillonite and vermiculite. Preliminary experiments using pulsed fields on vermiculite sols show that, in favourable circumstances, estimates of particle size can be made by analysing signal response rates.

698

Magnetic enhancement in nanoscale CoRh particles

The influence of size reduction on the magnetism of CoRh has been studied on a system of isolated nanometric spherical bimetallic ultrafine particles embedded in a polymer matrix. Pulsed fields up to 30 T were used in order to approach the magnetic saturation ( M(S)). Particles with a mean diameter of 1.65 (+/-0.1) nm display a value of 2.38 micro(B) per CoRh unit strongly enhanced compared to values calculated or measured on a bulk alloy. These results were interpreted as the first evidence of the cooperative role of both alloying and size reduction to the enhancement of M(S) in this system associating a 3d FM metal with a 4d metal.

699

Magnetic field anti-inflammatory effects in Crohn's disease depends upon viability and cytokine profile of the immune competent cells

AIM: We investigated effects of pulsating electromagnetic field (PEMF-50 Hz, 45 +/- 5 mT) on viability and cytokine production by human peripheral blood mononuclear cells (PBMC) from healthy donors and from Crohn's disease patients (CD). METHODS: The study was performed after activation of cells with phytohaemaglutinin (PHA) and lipopolisaccharide (LPS). Exposure of PBMC cultures to PEMF from both CD patients and from healthy donors decreased cell's viability of about 10% and 5% (p>0.05) respectively. PEMF influence was most effective after threefold application. Susceptibility of PBMCs to magnetic field exposure differs among the stimulated (PHA, LPS) and not stimulated (NS) cells. Mitogen activated cells during cell division are most susceptible to induction of the cell death as a result of magnetic interaction, contrary PEMF exposure has minimal effect on non-diving PBMCs from CD patients and from controls. Decreased viability of the Crohn derived cells upon magnetic stimulation was accompanied by altered cytokines profile. Exposed and stimulated PBMCs from Crohn patients decreased IFN-gamma proinflammatory and increased IL-10 anti-inflammatory cytokine production. The electromagnetically induced cell death could be an important step for non-invasive PEMF treatment in chronic inflammatory diseases.

700

Magnetic field effects on pineal indoleamine metabolism and possible biological consequences

In recent years, there has been a great deal of publicity concerning the possible health effects of electric and/or magnetic field exposure. One of the most frequently reported observations after the exposure of animals to either electric or magnetic fields relates to alterations in the metabolism of serotonin (5HT) to melatonin within the pineal gland. This review summarizes these results particularly in animals exposed to intermittently inverted, non-time varying magnetic fields, i.e., pulsed static magnetic fields. When exposure occurs at night, the conversation of 5HT to melatonin is typically depressed, not unlike that after light exposure at night. The mechanisms by which pulsed magnetic fields alter the ability of the pineal to convert 5HT to the chief pineal hormone melatonin remains unknown but may involve effects on any or all of the following: the retinas, the suprachiasmatic nuclei, the peripheral sympathetic nervous system, and the pinealocytes. Results to date suggest that induced electrical currents (eddy currents) produced by the pulsed magnetic fields are particularly detrimental to pineal indoleamine metabolism and may be an important causative factor in the metabolic changes measured. The physiological consequences of perturbations in the melatonin rhythm induced by magnetic field exposure remain unknown.

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