COMMISSION K: Electromagnetics in Biology and Medicine (November 2004 – October 2007)
Edited by Tsukasa Shigemitsu
K1 Biological Effects of Electromagnetic Fields
K1.1 DC and ELF Electric Fields
K1.2 Magnetic Orientation-microorganisms and Agarose
K1.3 DC and ELF Magnetic Fields
K1.3.1 In Vivo Studies
K1.3.2 In Vitro Studies
K1.3.3 Other Studies
K1.4 IF Magnetic Field
K1.5 RF Electromagnetic Field and Microwaves
K1.5.1 In Vivo Studies
K1.5.2 In Vitro Studies
K1.5.3 Other Studies@
K2 Field measurement, Dosimetry and Exposure Asessment
K2.1 DC and ELF Fields
K2.2 IF Magnetic Field
K2.3 RF Electromagnetic Field and Microwaves
K3 Tissue Properties, Materials, and Phantoms
K3.1 Design Methods of the Electromagnetic Environment@
K3.2 Phantoms and Tissue Properties-Bioelectromagnetics Parameters
K4 Biomedical Applications
K4.1 Magnetic Stimulation
K4.2 Thermal Therapy
K4.3 Thermal Therapy-Soft Heating and Inductive Heating
K4.4 MRI and Current Distribution MRI
K4.5 Contactless Power Transmission System
K4.6 Electromagnetic Intereference
research activities on the biological effects of electromagnetic fields in
This report does not describe every paper of the member of Japanese Commission K that has been carried out during 2005-2007. It begins with a chapter describing the recent published papers of the biological effects of electromagnetic fields. Next chapter reviews the results of electromagnetic field measurement, dosimetry and exposure assessment. Third and forth chapters provide a state-of-the-art review of biomedical applications using thermal therapy, hyperthermia with soft-and inductive-heating, MRI, and current distribution MRI, and further discuss some of the EMI issue on implantable medical devices.
K1 Biological Effects of Electromagnetic Fields
K1.1 DC and ELF Electric Fields
the mechanism of field perception, Shimizu et
al. conducted a fundamental study on the movement of body hair in field
Kagawa et al. have pursued the possibility to control immune functions by ELF electro-stimulation [Kagawa, 2006]. The effect of ELF electro-stimulation on the nitiric oxide (NO) producing ability of macrophages was examined. The decrease of NO production due to the electro-stimulation was observed with statistical significance. The measurement showed the decrease of the NO synthesizing enzyme with statistical significance, as well. These facts suggested that the ELF electro-stimulation suppressed the emergence of the NO synthesizing enzyme and that the amount of NO production was consequently decreased by the electro-stimulation. This suggested the feasibility to control the immune function by applying ELF electro-stimulation from outside the body.
Hirata et al. investigated the effect of low-frequency (ELF) electric stimulation to muscle oxygenation level by NIRS (near infrared spectroscopy) from comparing with V-Ex (voluntary exercise) [Hirata, 2006]. ELF electric stimulaiton voltage was started at 20 V (20 Hz, pulse duration: 200 Ês, duty-cycle: 1s-1s), and then was increased at a rate of 3 V/30 s until maximal tolerance level. In ELF electric stimulation and V-Ex, tissue oxygenation index was decreased with decrease in O2Hb (oxy-hemoglobin) and increase in HHb (deoxyhemoglobin), and muscle oxygenation levels at the end of test were very alike. Oxygen consumption, heart rate, systolic and diastolic blood pressure in ELF electric stimulation and V-Ex increased significantly, however, the degree of change in ELF electric stimulation was significantly lower than V-Ex. Blood lactate was significantly increased in both tests. Adrenaline and noradrenaline were significantly increased in V-Ex, even though they showed no change in ELF electric stimulation. These results suggest that ELF electric stimulation is an effective technique activated muscle hypoxia and glycolytic pathway metabolism with low stress on respiratory, circulatory and sympathetic nervous systems.
Muraki et al. investigated cardiorespiratory responses and muscle
oxygenation during prolonged electrical stimulation (ES)-evoked leg cycling in
individuals with paraplegia (
Miyazaki et al. measured somatosensory evoked fields (SEFs) by electric
stimulus to the right finger using a 39-channel SQUID system [
Oinuma et al. studied the influence of high-frequency monopolar stimulation (HFMS) on the rat cerebral cortex [Oinuma, 2007]. Direct stimulation of the brain with 500 Hz HFMS is one of the most common methods to produce motor evoked potentials (MEP). HFMS of 1.5-50 mA were applied to the rat sensorimotor cortex. There was no change in the parameters of MEP in any of the rats exposed to HFMS. Histologically, there was significant swelling of the dendrites in rats immediately after exposure to 40 and 50 mA. The 50 mA stimulation group also exhibited slight swelling of the mitochondria. These findings were not obtained in any of the rats 30 days after stimulation. In rats exposed to 30 mA or less, no morphological or electrophysiological changes were observed.
Nishiyama et al. investigated the effects of electrostatic fields on the storage of red blood cell concentrates [Nishiyama, 2007]. The Na+ concentration decreased with time but was significantly lower in the 0 V than in the 500, 1500, and 3000 V groups. K+ and free hemoglobin concentrations increased with time, with significantly higher values in the 0 V than in the 500, 1500, and 3000 V groups. The pH decreased in the 500, 1500, and 3000 V groups, while it did not change in the 0 V group. The pH decrease was smaller in the 500 V than in the 1500 and 3000 V groups. Electrostatic fields of 500-3000 V could decrease hemolysis in the preparation. Considering the lower pH decrease, it is suggested that 500 V might be the field of choice.
Harakawa et al. examined the effects of exposure to extremely low frequency (ELF) electric fields on plasma lipid peroxide levels and antioxidant activity (AOA) in Sprague-Dawley rats [Harakawa, 2005]. The test was based on comparisons among rats treated with a combination of the oxidizing agent, 2,2-azobis(2-aminopropane) dihydrochloride (AAPH) and 50 Hz electric field of 17.5 kV/m for 15 min per day for 7 days, AAPH alone, ELF electric field alone or no treatment. The ELF electric field significantly decreased the plasma peroxide level in rats treated with AAPH, similar to treatment by ascorbic acid or the superoxide dismutase. Ascorbic acid increased AOA; however, ELF electric field and superoxide dismutase did not change AOA compared with sham exposure in stressed rats. No influence on the lipid peroxide level and AOA in unstressed rats was observed with ELF electric field exposure alone. Although the administration of AAPH decreased AOA, this decrease did not change when electric field was added. These data indicate that the ELF electric field influenced the lipid peroxide level in an oxidatively stressed rat.
K1.2 Magnetic Orientation-microorganisms and Agarose
The past studies showed that the collagen fibers and adherent cells can be effectively oriented under the exposure to strong magnetic field. These challenges can lead to the development of bone tissue engineering. In order to achieve more clearly this phenomena, Saito et al. investigated the relationship between collagen orientation and magnetic field intensity [Saito, 2006]. The osteoblast cells were prepared and mixed with collagen solution. These mixed solutions were exposed to magnetic field with 2.5, 3 and 8 T. Five days later, the configulation of the osteoblasts was observed under microscope. These results showed the magnetic field intensity over 3 T is necessary to effectively control collagen orientation.
Several studies were carried out on the control of cellular orientation and morphology by applying strong static magnetic fields. Iwasaka et al. found that the motion of adherent cells (MC3T3-E1) was influenced by a static magnetic field of 8 T and was parallel to the static magnetic field [Iwasaka, 2005]. During the exposure, most cells showed a back-and-forth motion along the direction of the static magnetic field. Specifically, the direction of cell extension immediately after cell division was parallel to the static magnetic field. Cytoskeletons inside the cells were oriented in parallel with the static magnetic field, and introduced a cell motion parallel with the static magnetic field. The experiments showed that living cells consisting of diamagnetic materials had their motion restricted by the direction of the applied static magnetic field.
Diamagnetic anisotropy in cellular components provided a change in the fluidity of membrane assembly which was detected by fluorescent measurements in-situ under magnetic field exposures [Iwasaka, 2006c]. A novel phenomenon was discovered on the structures of giant vesicles which were formed under 8 T magnetic fields, and the contributions of both diamagnetic anisotropies of collagen molecules and lipid molecules were explained on a mathematical model [Suzuki, 2007a].
Effects of static magnetic fields on the optical property of cytochrome oxidase, which is involved in an enzymatic system of mitochondria, were investigated by utilizing purified enzymes and rabbit with a non-invasive oxygen monitor, and the results indicated a slight increment in oxidation of cytochrome oxidase by 14 T magnetic fields [Iwasaka, 2006a]. Iwasaka et al. reported the effects of intense static magnetic field (up to 14 T) on the near-infrared (NIR) optical properties of cytochrome oxidase in rabbits. The static magnetic field changed the oxidation of cytochrome oxidase (aa3) periodically depending on the magnetic flux density. Measurements with a cooled CCD system revealed that the absorbance at 830 nm was slightly increased by a static magnetic field of 8 T. A static magnetic field of 14 T was applied to the head of the rabbit, and the results showed the enhanced oxidation of cytochrome oxidase in the mitochondria of cells under the static magnetic field. The effects of the static magnetic field on the paramagnetic behavior of oxygen, electron transfer in cytochromes, and cell membrane conformation in mitochondria may play a role in increasing the sensitivity to NIR light for detecting cytochrome oxidase oxidation, which is one of the primary indicators of cellular activity.
Iwasaka et al. further reported a method of controlling the magnetic orientation of osteoblasts by utilizing a ferromagnetic particle chain and a diamagnetic collagen [Iwasaka, 2006b]. A cell culture medium with cells and magnetic particles (MP) was mixed with a collagen solution and incubated for 24 h. During the first 3 h of incubation, the medium in the cell culture dish was exposed to static magnetic field of up to 8 T. The exposure caused the aggregation of MP, which formed chains in parallel with the static magnetic field and at the same time oriented the polymerized collagen fibers perpendicular to the static magnetic fields. A lattice pattern of MP chains and collagen fibers was observed on the bottom of the culture flask. After 24 h of incubation, the spindle like cells had become oriented in parallel with the MP chains or the collagen fibers. The results indicate the possibility of a technique of cellular manipulation with MP-collagen hybrid that could be used to control cellular orientation.
An experiment to clarify the effects of the static magnetic field of up to 8 T on cell membrane fluidity by using red blood cell ghosts and a fluorescence dye, 1-aminonaphthalene-8-sulfonic acid (ANS) was performed [Iwasaka, 2006c]. The emission intensity at 480 nm increased when the temperature of the cell holder was increased from 20 to 38-46C for 15 min. A change in temperature exhibited an increase in the fluidity of the lipid molecules in the hydrophobic cell membrane and increased the population of ANS molecules emitting light at 480 nm in the cell membrane. A discontinuous change in fluorescence at 38-40C was exhibited under exposure to a 5 T static magnetic field, while the temperature dependency was continuous without exposure. In addition, under exposure to the static magnetic field, the fluorescence during a decrease in temperature from 38 to 20C remained at a level close to the fluorescence during an increase in temperature. The results indicated that the fluidity of the molecules in the cell membrane was decelerated by 5 T static magnetic field. They speculated that the magnetic orientation in a part of the lipid membrane disturbed the release of ANS molecules from a hydrophobic region of the membrane.
According to applications of magnetic forces, which are of a spatial gradient of magnetic flux density, for a biological process, Mosesf effect was applied to the patterning of adhered cells by using a field modulator under 1 T [Kimura, 2005]. Also, two kinds of new approaches in magnetic separation techniques for biological materials were reported, one of which was called gmagnetic liquid chromatographyh [Iwasaka, 2007], and the other was an application of the Magneto-Archimedes separation [Yokoyama, 2007].
Kimura et al. presented a new technique of cell micropatterning using a magnetic field [Kimura, 2005]. Mouse osteoblast cells (MC3T3-E1) were seeded on a substrate whose surface was exposed to a periodically modulated magnetic field (a line pattern with a 200- or 600-Êm pitch) produced by a field modulator inserted into a homogeneous static magnetic field of 1 T. The cells were trapped consistent with the line profile of the modulated magnetic field. The trapping efficiency was enhanced by adding Mn (II) EDTA (paramagnetic) to the cultivation medium. The cells were subsequently incubated in the magnetic field. The same technique was applied to whole blood to pattern red blood cells.
al. examined the role of cytoskeletons, such as stress fibers, on magnetic
orientation of Schwann cells after the static magnetic field exposure (8 T in
maximum) [Eguchi, 2005]. Schwann cells were cultured from dissected sciatic
nerves of neonatal rats. Schwann cells oriented parallel to the static magnetic
field after 60 h of more than 4 T. Actin fibers oriented in the direction of
the static magnetic field after 60 h of 8 T static magnetic field exposure but
randomly oriented without static magnetic field. Orientation of Schwann cells
was not observed by inhibiting stress fiber formation using Y-27632, an
inhibitor of small guanosine triphosphatases (GTPase) Rho-associated kinase.
These results indicate that the static magnetic field elicits reorientation of
actin fibers through
Eguchi et al. further examined cleavage and survival of fertilized Xenopus embryos exposed to 8 T static magnetic field [Eguchi, 2006]. Fertilized Xenopus embryos exposed to static magnetic field either in a static chamber or in a rotating culture system. The results showed that the static magnetic field exposure changed the third cleavage furrow from the usual horizontal one to a perpendicular one; however, when the direction of gravity was randomized by exposing embryos to the static magnetic field in a rotating culture system, the third cleavage furrow were formed horizontally. These findings suggest that the observed distortion of the third cleavage furrow in static magnetic field exposed embryos was accomplished by altering gravity effects which were elicited by diamagnetic force due to high gradient magnetic field. These results also showed that the exposure to the static magnetic field did not damage survival. These results demonstrate that static magnetic field and altering gravity cause distortion of the third cleavage furrow and show that effects of exposing cleavage embryos to static magnetic field were transient and did not affect the post-cleavage development. They also showed that static magnetic field is not hazardous to the cleavage and blastula-gastrula transition of developing embryonic cells.
Shinohara et al. reported highly oriented collagen structures were successfully synthesized using a conventional superconducting magnet with static magnetic field of 2.5 to 8 T [Shinohara, 2006]. The relationship between the orientation order parameters f2D of osteoblastic cells (the orientation of collagens) and the magnetic field intensity was mainly investigated. As a result, it was clarified that collagens highly oriented perpendicular to the c direction were obtained by exposure to a static magnetic field of 3 T.
After the short-time exposure of pregnant mice (60 min on 1 day from 7.5 to 14.5 days of pregnancy) to a strong magnetic field of 400 mT (exposure direction was in a dorso-ventral direction), Saito et al. evaluated the teratologic effects of developing fetuses [Saito, 2006]. 160 animals were used in the exposure experiment; exposed and control groups consisted of 10 pregnant mice each. Teratological evaluation was performed on day 18.5. The number of live and dead fetuses and fetal resorption sites were counted. All fetuses were examined from gross malformation and gender. They observed various malformations and the type of malformations were polydactylism, abdominal fissure, fused rib, vestigial 13th rib, lumber rib, brain hernia and curled tail. In control groups only a low incidence (up to 2.8 %) of curled tail was observed. The mentioned these deforations apparently caused by static magnetic field.
A National Project Group for research on strong static magnetic field effects on physico-chemical processes partially including biological matters collected results of recent topics [Yamaguchi and Tanimoto, 2006].
K1.3 DC and ELF Magnetic Fields
During past three years, three comprehensive review papers have been appeared [Kato, 2006; Miyakoshi, 2005a; Ueno, 2007b]. Kato edited the book entitled gElectromagnetics in Biologyh. This comprehensive book covered the fundamental concept of biological issue in electromagnetics and the topical reviews of the published literature. Miyakoshi reviewed the effects of static magnetic feld at cellular level. As a result through reviewing many past published studies, he mentioned that static magnetic field alone does not have a lethal effect on basic propertes of cell growth and survival under normal culture condition regardless of the magnetic density. Most studies have also suggested that a static magnetic field has no effect on changes in cell growth rate. Most interest area is whether static magnetic fields cause DNA damage. Ueno and Shigemitsu reviewed some of the more recent information on biological effects and medical applications of static magnetic fields. In their review, with exposure to about 1 T and above, there are no adverse effects on reproduction and development, genotoxicity, and molecular and cellular systems, and no consistent evidence on behavioral effects. Most important point they mentioned was that the International Agency for Research on cancer (IARC) has stated the static magnetic field are not classifiable as to their carcinogenicity to humans by inconclusive carcinogenic evidence.
K1.3.1 In Vivo Studies
Okano et al. reported that the homeostatic effect of the static magnetic field might influence nitric oxide (NO) pathways [Okano, 2005a]. When the genetically hypertensive rats were exposed to a gradient static magnetic field of 5 mT for up to 12 weeks, blood pressure (BP) and/or plasma concentration of NO metabolites (NOx), angiotensin II and/or aldosterone were reduced. Specifically, 5 mT exposures reduced mean BP during 3-6 weeks. Young spontaneously hypertensive rats (SHR) are known to have increased levels of NOx, likely due to the upregulation of nitric oxide synthase (NOS). Exposure to a 5 mT static magnetic field for 6 weeks significantly reduced the concentration of NOx. A 1 mT static magnetic field did not have an effect on the NOx. A 5 mT static magnetic field reduced angiotensin II and aldosterone during 3-6 weeks. Similar significant reductions in angiotensin II and aldosterone were seen with the 1 mT static magnetic field. However, until the 9th week of exposure, irrespective of the longer duration of exposure, all significant antihypertensive effects of static magnetic field disappeared, due to the development of hypertension in young SHR.
The above findings were partially elucidated when SHR were exposed to a 180 mT static magnetic field (a magnet was implanted in the neck) for up to 14 weeks [Okano, 2005d, 2006a]. The static magnetic field enhanced the hypotensive effect of nicardipine and caused a further increase in NOx during the 6th week of exposure compared with rats that also received nicardipine but were exposed to a sham field (control). Thus, the synergistic effect of the static magnetic field appeared to be related to NO. The static magnetic field alone (without nicardipine), however, did not induce any change in NOx concentration. It is speculated that NO increase by static magnetic field, in part, might be due to the upregulation of inducible NOS rather than neuronal NOS or endothelial NOS [Okano, 2006a].
The homeostatic effects of a static magnetic field were again reinforced when reserpine, an indole alkaloid, was used to induce hypotension and deplete catecholamine reserves in conscious rats [Okano, 2005b]. The static magnetic field exposure (25 mT for 12 weeks) significantly reduced the effect of the reserpine, reducing the hypotension caused by the drug. A 10mT static magnetic field did not have any effect. It is concluded that a 25 mT static magnetic field could potentially reduce hypotension in vivo.
The combined effects of a static magnetic field (12 mT for 10 weeks) and two different sympathetic agonists were investigated in conscious rats [Okano, 2007a]. The two different sympathetic agonists, a ¿1-adrenoceptor agonist, phenylephrine and a À1-adrenoceptor agonist, dobutamine, induced hypertension and different hemo- dynamics: phenylephrine increased BP and decreased heart rate, skin blood flow, skin blood velocity, and the number of rearing responses; dobutamine increased BP and heart rate, increased skin blood flow and velocity, and the number of rearing responses. Continuous neck exposure to the static magnetic field alone for up to 10 weeks induced no significant changes in any of the measured cardiovascular and behavioral parameters. The static magnetic field exposure for at least 2 weeks (1) significantly depressed phenylephrine effects on BP, skin blood flow and velocity, and rearing activity, and (2) significantly depressed dobutamine effects on BP, skin blood flow and velocity, and suppressed dobutamine-induced increase in the rearing activity. These results suggest that continuous neck exposure to a 12 mT static magnetic field for at least 2 weeks may depress or suppress sympathetic agonists-induced hypertension, hemodynamics, and behavioral changes by modulating sympathetic nerve activity.
In the case of neck application of the static magnetic field, Okano et al. found that the exposure to 5.5 mT for 30 min induced significant increases in baroreflex sensitivity (BRS) values during the post-exposure period of 40-60 min in norepinephrine-elevated BP compared with sham exposure in conscious rabbits [Okano, 2005c]. Moreover, the exposure to the static magnetic field for 5-8 weeks significantly suppressed or delayed the development of hypertension together with increased BRS in SHR [Okano, 2005d]. Furthermore, it is postulated through theoretical calculations that the applied static magnetic field can be converted into a changing magnetic field in the baroreceptor region by means of the carotid artery pulsation [Okano, 2005d]. Therefore, it is speculated that the changing magnetic field and the magnetic field modulated by the pulse rate, may influence the activity of baroreceptor and baroreflex function.
Xu et al. investigated the effects of the static magnetic field (180 mT for 3 weeks) on the vascularization in bone using an ischemic bone model, where rat femoral artery was ligated [Xu, 2007]. Magnetized and unmagnetized samarium-cobalt rods were implanted transcortically into the middle diaphysis of the ischemic femurs. Collateral circulation was evaluated by injection of microspheres into the abdominal aorta at the third week after ligation. It was found that the bone implanted with a magnetized rod showed a larger amount of trapped microspheres than that with an unmagnetized rod at the proximal and the distal region. There were no significant differences at the middle and the distal region. This tendency was similar to that of the bone mineral density (BMD) in the static magnetic field exposed ischemic bone.
Taniguchi et al. examined the effects of the static magnetic field (30 mT for 12 weeks) on osteopenia in an ovariectomized (OVX) rat model [Taniguchi, 2007]. The bone mineral densigty (BMD) was assessed mainly using dual-energy X-ray absorptiometry (DEXA). Thirty-six female Wistar rats were divided into three groups. The rats in the OVX-M group were exposed to the static magnetic field for 12 weeks after ovariectomy. The ovariectomized rats in the OVX-D group were not exposed to the static magnetic field as a control. The rats in the normal group received neither ovariectomy nor exposure to the static magnetic field. Twelve-week exposure to the static magnetic field in the OVX-M group inhibited the reduction in BMD that was observed in the OVX-D group. Moreover, in the OVX rats, before exposure to the static magnetic field, there was no clear difference in the level of locomotor activity between the active and resting phases, and the pattern of locomotor activity was irregular. After exposure of OVX rats to the static magnetic field, the pattern of locomotor activity became diphasic with clear active and resting phases, as observed in the normal group. In the OVX-M group, the continuity of the trabecular bone was maintained more favorably and bone mass was higher than the respective parameters in the OVX-D group. These results demonstrate that exposure to the static magnetic field increased the level of locomotor activity in OVX rats, thereby increasing BMD.
Goto et al. examined the effects of the static magnetic field (100 mT for 2 h, four times per day for 7 days) affects higher order neural functions in vivo [Goto, 2006]. When embryonic 12-day-old or newborn mice were successively exposed to the static magnetic field at 100 mT for 2 h, four times per day until the postnatal seventh day, Ntan1 mRNA was significantly increased about 1.5-2-fold in the hippocampus in vivo. The mice exposed to the static magnetic field under the same condition showed significantly decreased locomotor activity. These results suggest that the static magnetic field affects higher order neural functions through modulation of genes expression.
Toyomaki et al. investigated the static magnetic field (1.5 T) affects brain activity such as arousal level [Toyomaki, 2007]. They compared the electroencephalography (EEG) inside an MRI scanner in the presence/absence of the static magnetic field in two different arousal levels of task and rest conditions in humans. Cardiac-related pulsations of head and blood flow induce an electric voltage at each EEG electrode in a static magnetic field. This induced voltage overlaps with the intrinsic EEG signal and becomes a large confounding factor. No significant difference was observed in the intrinsic EEG in the absence of a magnetic field, whereas in the presence of the static magnetic field, the theta frequency band of the intrinsic EEG increased, especially during the task condition, but other frequency bands did not change. These results demonstrate that a static magnetic field affects brain activity.
Sekino et al. investigate the effects of strong static magnetic field (up to 8 T) on the action potentials of the rat sciatic nerve [Sekino, 2006c]. A pair of needle electrodes was inserted beneath the skin of the heel for applying electrical stimulations. Compound action potentials of the left sciatic nerve were measured from a pair of electrodes attached to the nerve bundle under the static magnetic field. We identified the action potentials originating from the A and C fibers. The exposure to static magnetic field did not affect the amplitude of the A fiberfs action potentials. An increase in the static magnetic field increases the amplitudes of the peaks of the C fiber. These results indicated that exposure to strong static magnetic field enhances the excitation of nerve fibers, and this effect depends on the type of fibers involved. These result implies that exposure to a strong static magnetic field enhances pain perception because the C fiber is responsible for pain transmission.
Komazaki et al. examined the influence of an extremely low frequency (ELF) magnetic field (50 Hz, 5-30 mT) on early development of amphibian embryos [Komazaki, 2007]. When the embryos developed under the influence of an ELF magnetic field, the rate of early development was accelerated. The effect of ELF magnetic field was exerted preferentially at the gastrula stage, and the period of gastrulation was shortened. Histological observations showed that ELF magnetic field promoted morphogenetic cell movements during the gastrulation. ELF magnetic field increased intracellular Ca2+ ([Ca2+]i) particularly in the cells isolated from gastrula. These results suggest that ELF magnetic field specifically increased the [Ca2+]i of gastrula cells, thereby accelerating the rate of morphogenetic cell movements during gastrulation.
In order to study the infleunce of magnetic field (60 Hz, 0.5 T, one hour exposure) on the nervous system of nematode C.elegans, Maeda et al. observed the behavior of the worm in response to certain chemicals (DA and CuSO4) both during the exposure and after exposure to magnetic field [Maeda, 2006]. They suggested that the parts of the wormfs nervous system are influenced by magnetic fields and there are more effects on the nervous system during than after exposure to magnetic fields.
Suzuki et al. investigated the effect of static magnetic field of 4.7 T on the induction of micronuclei induced by some mutagens in order to confirm the co-mutagenic effect [Suzuki, 2006]. Seven-week-old BALB/c male mice with body weights between 22-27 g were exposed to 4.7 T magnetic fields just after the injenction of carboquone (0.5, 1.0 and 2.0 mg/kg), colemid (1.25, 2.5, 5.0 and 7.5 mg/kg), mitomycin C (0.3, 0.5 and 0.7 mg/kg), vincristine (0.02, 0.03 and 0.04 mg/kg), sodium fluoride (10. 20 and 30 mg/kg) or ENU (9. 18 and 36 mg/kg). After exposure to magnetic field, the mice were sacrified by cervical dislocation. Bone marrow smears were prepared. The number of micronucleated polychromatic erythrocytes in 1000 polychromatic erythrocytes per animal was counted under a light microscope. The frequency of micronuclei induced by above six mutagens increased after co-exposure to magnetic field. The authors concluded that an additive/synergistic effect of magnetic field was observed from the results of increased frequency of micronuclei by mutagens in mouse bone marrow erythrocytes.
Ogiue-Ikeda et al. investigated the acquisition of ischemic tolerance in the rat hippocampus using repetitive transcranial magnetic stimulation (rTMS) which is a type of ELF-pulsed magnetic fields (ELF-PEMF) [Ogiue-Ikeda, 2005]. Rats received ELF-PEMF (0.75 T, 1000 pulses/day) for 7 days, and the field excitatory postsynaptic potentials were measured in the hippocampal CA1. After slices were exposed to ischemic conditions, long-term potentiation (LTP) was induced. The LTP of the stimulated group was enhanced compared with the LTP of the sham control group in each ischemic condition, suggesting that ELF-PEMF has the potential to protect hippocampal function from ischemia.
Funamizu et al. examined the effects of an ELF-PEMF on neurological and psychiatric disorders [Funamizu, 2005] As an animal model, the lesioned rats were made by administering the neurotoxin MPTP (l-methyl-4-phenyl-l, 2, 3, 6-tetrahydropyridine). Forty-eight hours after MPTP injection, the rats received ELF-PEMF (1.25 T, 2000 pulses/day) for 1 day, and tyrosine hydroxylase (TH) and NeuN expressions were investigated in the substantia nigra. The functional observational battery-hunched posture score for the MPTP-ELF-PEMF group was significantly lower and the number of rearing events was higher compared with the MPTP-sham group, these behavioral parameters reverted to control levels. These results suggest that ELF-PEMF treatment could reactivate the dopaminergic system in lesion rats.
Yamaguchi et al. investigated the effects of an ELF-PEMF on tumor development processes and immune functions in vivo [Yamaguchi, 2005ab, 2006a]. ELF-PEMF were applied at pulse width = 238 Ês, peak magnetic field = 0.25 T, frequency = 25 pulses/s, 1,000 pulses/sample/day and magnetically induced eddy currents = 0.79-1.54 A/m2. B16-BL6 melanoma model mice were exposed to the ELF-PEMF for 16 days from the day of injection of cancer cells. A tumor growth study revealed a significant tumor weight decrease in the ELF-PEMF group. These results showed the anti-tumor effect and immunomodulatory effects of ELF-PEMF.
Yamaguchi et al. further examined the combination effect of an ELF-PEMF and an anticancer agent on human chronic myelogenous leukemia-derived cell line TCC-S using molecular target drug (selective tyrosine kinase inhibitor) imatinib mesylate (imatinib) [Yamaguchi, 2006b]. The stimulus conditions were determined as follows: 0.1, 0.25, and 0.5 T, 25pulses/s, 1000, 3000, and 6000 pulses/day. TCC-S cells were cultured with imatinib (100 nM) and exposed to ELF-PEMF for up to 56 h after drug treatment. The significant combination effects of ELF-PEMF and imatinib occurred by the stimulus intensity and pulse dose depended manner. To clarify the effects of ELF-PEMF on human normal lymphocytes, PBMCs were also exposed to ELF-PEMF with or without imatinib. ELF-PEMF had no effect on the viability of PBMCs. These results indicate that ELF-PEMF possibly improve the effectiveness of anticancer agents.
Mano et al. investigated the effect of ELF magnetic field (60 Hz, 5 mT) on the germination of seeds [Mano, 2006]. The germination of seeds of Arabidopsis thaliana, Lactuca sativa and Zinnia elegans were decreased by 8-21 day-incubation in 90 % relative humidity at 37 . ELF magnetic field applied to seeds during the incubation suppressed these decreases in the germination. The ELF magnetic field suppressed irreversible deterioration of the seeds, rather than dormancy, probably preventing water absorption. ELF magnetic field can be helpful for the storage of humidity-vulnerable seeds.
K1.3.2 In Vitro Studies
Hirai et al. reported repetitive daily exposure to a static magnetic field (100 mT for 15 min per day for 8 days) led to a decrease in the expression of microtubule-associated protein-2 (MAP-2), without significantly affecting cell viability or the expression of neuronal nuclei (NeuN) and growth-associated protein-43 (GAP-43) [Hirai, 2005a]. However, the repetitive static magnetic field exposure prevented decreases in both brain-derived neurotrophic factor (BDNF) mRNA and MAP-2 and additionally increased the expression of NR2A subunit, without altering NR1 expression in neurons cultured in the presence of the antagonist for N-methyl-D-aspartate (NMDA) receptors dizocilpine (MK-801). Repetitive static magnetic field exposure was also effective in preventing the decrease by MK-801 in the ability of NMDA to increase intracellular free Ca2+ ions, without affecting the decrease in the maximal response. These results suggest that repetitive static magnetic field exposure may at least in part counteract the neurotoxicity of MK-801 through modulation of the expression of particular NMDA receptor subunits in cultured rat hippocampal neurons.
Hirai et al. examined the effects of a static magnetic field (100 mT for 15 min) on cultured rat hippocampal neurons using polymerase chain reaction [Hirai, 2005b]. The results suggest that the static magnetic field may modulate cellular integrity and functionality through expression of a variety of responsive genes required for gene transcription and translation, proliferation, differentiation, maturation, survival, and so on. in cultured rat hippocampal neurons. Hirai et al. screened genes responsive to a brief static magnetic field i100 mT for 15 min) in cultured rat hippocampal neurons using differential display analysis [Hirai, 2006]. These results suggest that a brief static magnetic field leads to the induction of amidohydrolase for N-terminal asparagines (Ntan1) responsible for MAP2 protein degradation through ubiquitin-proteasome pathway in rat hippocampal neurons.
Okano et al. reported the effects of the static magnetic field (120 mT for 10 days) on increased endothelial tubular formation mostly in the absolute field gradient range of more than 28 mT/mm (28 T/m) in the target cells [Okano 2006b, 2007b, 2007c]. These studies investigated the spatial magnetic gradient effects of static magnetic field on endothelial tubular formation. The effects of gradient static magnetic field on tubular formation were compared with those of uniform static magnetic field that has no spatial gradients on the entire bottom area of culture wells [Okano 2007c]. Five experimental groups of 25 samples each were examined: (1) sham exposure (control); (2) peak gradient exposure in the peripheral part; (3) peak gradient exposure in the central part; (4) uniform exposure to 20 mT; (5) uniform exposure to 120 mT. The static magnetic field or sham exposure was carried out for 10 days. Photomicrographs of tubular cells, immunostained with an anti-platelet-endothelial cell adhesion molecule-1 (PECAM-1 [CD31]) antibody as a pan-endothelial marker, were analyzed after the 10-day culture. Gradient static magnetic field in the peripheral or central part was found to significantly promote tubular formation in terms of the area density and length of tubules in each peak gradient/force part of the wells, compared with the sham exposure. In contrast, uniform static magnetic field did not induce any significant change in the tubular formation. These findings suggest that tubule formation can be promoted by applying the peak gradient/force to a target site of culture wells.
Haneda et al. examined the effects of the static magnetic field (300 mT for several hours) on single suspension-cultured plant cells (Catharanthus roseus) [Haneda, 2006]. Exposure of intact cells to the static magnetic field did not result in any changes within experimental error, while exposure of regenerating protoplasts significantly increased the measured forces and stiffened regenerating protoplasts. The diameters of intact cells or regenerating protoplasts were not changed after exposure. Measured forces for regenerating protoplasts with and without exposure increased linearly with incubation time, with these forces being divided into components based on the elasticity of synthesized cell walls and cytoplasm. No changes in cell wall synthesis were noted after exposure. Analysis suggested that the static magnetic field roughly tripled the Young's modulus of the newly synthesized cell wall without any lag.
Sakurai et al. reported that exposure to the static magnetic field of up to 10 T promoted osteoblast differentiation in vitro [Sakurai, 2007a]. Prostaglandins respond early to exogenous mechanical loading, and play an important role in bone formation. The magnetic field gradient was highest (41.7 T/m) at 6 T. Prostaglandin E2 (PGE2) secretion was not affected at 10 T compared with sham exposure, but was enhanced at 6 T. Similarly, PGE2-synthesizing enzyme, cyclooxygenase 2 (Cox-2) expression and the transcription factor nuclear factor ÈB (NF-ÈB) translocation were not enhanced at 10 T, but increased at 6 T. These findings suggested that exposure to a high magnetic field gradient induced secretion of PGE2 and expression of the Cox-2 protein via increased translocation of NF-ÈB.
Sakurai et al. evaluated the effects of an extremely low frequency (ELF) magnetic field on glucose-stimulated insulin secretion from HIT-T15 cells and investigated the mechanisms of these effects [Sakurai, 2005b]. They demonstrated that ELF magnetic field at 5 mT and 60 Hz decreased glucose-stimulated insulin secretion by preventing the increases in cellular adenosine 5'-triphosphate/adenosine 5'-diphosphate, membrane depolarization, and cytosolic free Ca2+ concentration. The glucose-induced upregulation of insulin mRNA expression was also attenuated by exposure to ELF magnetic field, although cell viability was not affected. These findings demonstrate the potential of exposure to ELF magnetic field for clinical use as a novel inhibitory method of insulin secretion.
Because there are few studies about the effects of an ELF magnetic field on À-cell survival and function, Sakurai et al. investigated the effects of 5 mT of 60 Hz magnetic fields on cell survival and function [Sakurai, 2005a]. The used cultured cell was a hamster-derived insulin-secreting cell line (HIT-T15). They cultured HIT-T15 cells under the exposure to sham and ELF magnetic field conditions. It was found that exposure to ELF magnetic field for 5 days in the absence of glucose increased cell number, exposure for 2 days without glucose aand for 5 days with 100 mg/dl glucose increased the insulin secretion, and exposure for 2 and 5 days with 40 and 100 mg/dl glucose increased intracellular insulin concentration in HIT-T15 cells. The increase in cell number under apoptotic culture condition by exposure to ELF magnetic field can lead to new therapeutic applications in the treatment of diabetes.
Koyama et al. investigated the effects of an ELF magnetic field (5 mT and 60 Hz) on the number of apurinic/apyrimidinic (AP) sites in human glioma A172 cells [Koyama, 2007a]. There was no difference in the number of AP sites between cells exposed to ELF magnetic field and sham controls. With methyl methane sulfonate (MMS) or H2O2 alone, the number of AP sites increased with longer treatment times. ELF magnetic field in combination with the genotoxic agents increased AP-site levels compared with the genotoxic agents alone. The results suggest that the number of AP sites induced by the genotoxic agents is enhanced by ELF magnetic field, presumably thereby lengthening the lifetime of radical pairs.
Fukushima et al. examined the effects of an ELF
magnetic field applied phosphate buffered saline solution (PBS) or water on ATP
Ono et al. evaluated the effect of 44 mT static magnetic field on glucose uptake as the energy source of the metabolic change, and on gene expression of glucose transporters (GLUT1 and GLUT3) [Ono, 2006]. The static magnetic field was applied to the cultured cells (30 x 104 cells/mL) for 8 or 24 h. The target cell was neuroblastoma NG108-15. Glucose uptake of the cells and mRNA expression was measured by the phenol-sulfuric acid method and RT-PCR technique, respectively. The results showed that the glucose uptake of the cells was enhaced in 8 h exposure, while the GLUT1 and GLUT3 mRNA expression shows no change. In contrast, in 24 h exposure to static magnetic field, the glucose uptake and GLUT1 and GLUT3 mRNA expression were suppressed. The authors suggested tha the metabolic activity change observed during the 24 h exposure may attribute to the change in glucose uptake and modification of GLUT1 and GLUT3 gene expression.
K1.3.3 Other Studies
Koyama et al. examined the effects of an ELF magnetic field (5 mT and 60 Hz) and/or X-rays on mutations in the supF gene carried by pTN89 plasmids in Escherichia coli (E. coli) [Koyama, 2005]. The plasmids were subjected to sham exposure or exposed to ELF magnetic field, with or without X-ray irradiation (10 Gy). Increased mutant fraction was not detected following exposure to ELF magnetic field alone, or after sham exposure. The mutant fraction for X-rays followed by an ELF magnetic field was significantly higher than those of other treatments. Sequence analysis of the supF mutant plasmids revealed that base substitutions were dominant on exposure to X-rays alone and X-rays plus an ELF magnetic field. Several types of deletions were detected in only the combined treatments, but not with X-rays alone. There were no mutant colonies in sham irradiated and an ELF magnetic field alone treatment, but exposure to ELF magnetic field immediately before or after X-ray irradiation may enhance the mutations. These results indicate that an ELF magnetic field increases mutation and alters the spectrum of mutations.
Ohkubo et al. reviewed the effects of static magnetic field of 0.3-180 mT, ELF magnetic field of 0.1-30 mT and microwave, 1.5 GHz with SAR of 0.08-8 W/kg on microcirculary system in different tissues in experimental animals of rat, rabbit, house and human [Ohkubo, 2007]. He emphasized that there is an importance of understanding the effects of magnetic fields on microcirculatory system. It may have direct and indirect role in interaction of magnetic fields with different tissues. The results obtained from ELF and RF electromagnetic field failed to show any changes in microcirculatory system except for leukocyte and endotherlial cell interaction. The animal study can contribute to evaluate possible health risks of electromagnetic field.
K.1.4 IF Magnetic Field
Chuman et al. first, investigated the effect of 20 kHz intermediate frequency (IF) magnetic field on Xenopus laevis [Chuman, 2007]. They compared the tail-length of frogs between exposed and control groups after exposure to IF magnetic field. The parameters were the exposure time and strength of magnetic field intensity. They used two exposure equipments, the commercial available induction heater (IH) cooker and Merritt coil type exposure facility. The results showed that the exposure may spped up metamorphosis of frog.
Tachi et al. investigated whether 20 kHz magnetic field of 0.5 mT and 1 mT induce DNA damage or physiologically abnormality in bacterial cells containing bacteriophage É [Tachi, 2005]. Their results showed that after exposure to magnetic field for about 4 and 8 hours, the prophages shifted to lytic growth more often than control group. The results were compared to the result of 60 Hz, 45 mT magnetic field exposure experiments. The comparison gave the both IF and ELF magnetic fields induce physiological damage in bacterial cells.
Morimoto et al. examined the effects of an intermediate frequency (IF) electromagnetic field (10 MHz for 24 h) on production of endothelin-1 (ET-1) in cultured endothelial cells [Morimoto, 2005]. IF electromagnetic field reduced ET-1 basal levels in human umbilical vein and microvascular endothelial cells, but failed to reduce ET-1 basal levels in bovine and human aortic endothelial cells. IF electromagnetic field significantly inhibited thrombin-stimulated ET-1 production in all four endothelial cell types in a dose-dependent manner. IF electromagnetic field significantly inhibited thrombin-induced endothelin-1 mRNA expression in all four cell types. The inhibitory effect of IF electromagnetic field on ET-1 production was abolished by the NOS inhibitor, NG-monomethyl-L-arginine (10-3 M). These results demonstrate that IF electromagnetic field modulates ET-1 production in cultured vascular endothelial cells and the inhibitory effect of IF electromagnetic field is, at least partly, mediated through a NO-related pathway.
Miyakoshi et al. examined the cellular genotoxicity of an IF magnetic field (532}20 ÊT at 23 kHz) in cultured cells [Miyakoshi, 2007]. Exposure to IF magnetic field for 2 h did not affect the growth of Chinese hamster ovary (CHO)-K1 cells and caused no mutagenic effects in bacterial mutation assays. Exposure to the IF magnetic field for 2 h induced neither single nor double DNA strand breaks in comet assays, and caused no significant change in the mutation frequency at the hypoxanthine-guanine phosphoribosyl transferase (HPRT) locus compared to sham exposure. The results suggest that exposure to an IF magnetic field for 2 h does not cause cellular genotoxicity in bacteria and in CHO cells.
Haga et al. investigated the effects of IF magnetic fields with 20 kHz, 600ÊT on living biological cells using a highly sensitive mutagenesis assay method [Haga, 2005]. A bacterial gene expression system for mutation repair (umu system) was used for the sensitive evaluation of damage in DNA molecules. Salmonella typhimurium TA 1535 (pSK 1002) was used in this study. No effect from exposure to 20 kHz, 600 ÊT magnetic field in terms of damage in DNA molecules were observed. @
Shigemitsu et al. reviewed the biological effects of IF electromagnetic fields with around 20 kHz from in vivo and in vitro studies [Shigemitsu, 2007]. After the short review based on published papers, they concluded that the available research data is inadequate for health risk assessment of IF electromagnetic fields. They also recommended that the study and exposure experiment of the biological and health effect of IF electromagnetic fields are very important.
K1.5 RF and Microwaves
K1.5.1 In Vivo Studies
Hata et al. studied the effects on melatonin synthesis in rats after short term exposure to a 1439 MHz time division multiple access (TDMA) electromagnetic field [Hata, 2005]. The average specific absorption ratio (SAR) of the brain was 7.5 W/kg, and the average SAR of the whole body were 1.9 and 2.0 W/kg for male and female rats, respectively. No significant differences in melatonin and serotonin levels were observed between the exposure, sham, and cage control groups. These results suggest that short term exposure to a 1439 MHz TDMA electromagnetic field (about four times stronger than that emitted by mobile phones) did not alter melatonin and serotonin synthesis in rats.
Kuribayashi et al. investigated the effects of 1439 MHz electromagnetic field exposure on the blood-brain barrier (BBB) were using immature (4 weeks old) and young (10 weeks old) rats [Kuribayashi, 2005]. Alteration of BBB related genes, such as those encoding p-glycoprotein, aquaporin-4, and claudin-5, was assessed at the protein and mRNA levels in the brain after local exposure of the head to electromagnetic field at 0, 2, and 6 W/kg SAR for 90 min/day for 1 or 2 weeks. Although expression of the 3 genes was clearly decreased after administration of 1, 3-dinitrobenzene (DNB) as a positive control, when compared with the control values, there were no pathologically relevant differences with the electromagnetic field at any exposure levels at either age. Vascular permeability was not affected by electromagnetic field exposure. Thus, these findings suggest that local exposure of the head to 1439 MHz electromagnetic field exerts no adverse effects on the BBB in immature and young rats.
Yuasa et al. investigated whether the radiofrequency electromagnetic fields (RF-EMF) emitted by a mobile phone for 30 min has short-term effects on human somatosensory evoked potentials (SEP) [Yuasa, 2006]. Neither SEP nor their recovery function was affected by exposure to RF electromagnetic field or sham phone use. The results suggest that 30 min mobile phone use has no short-term effects on the human sensory cortex.
Inomata-Terada et al. investigated whether RF electromagnetic fields emitted by a mobile phone has short-term effects on the human motor cortex [Inomata-Terada, 2007]. They measured motor evoked potentials (MEP) elicited by single pulse transcranial magnetic stimulation (TMS), before and after mobile phone exposure (active and sham) in 10 normal volunteers. Three sites were stimulated (motor cortex (CTX), brainstem (BST) and spinal nerve (Sp)). The short interval intracortical inhibition (SICI) of the motor cortex reflecting GABAergic interneuronal function was also studied by paired pulse TMS method. MEP to single pulse TMS was also recorded in two patients with multiple sclerosis (MS) showing temperature dependent neurological symptoms (hot bath effect). Neither MEP to single pulse TMS nor the SICI was affected by 30 min of RF electromagnetic field exposure from mobile phones or sham exposure. In two MS patients, mobile phone exposure had no effect on any parameters of MEP even though conduction block occurred at the corticospinal tracts after taking a bath.
Terao et al. investigated whether exposure to pulsed high-frequency electromagnetic field (pulsed EMF) emitted by a mobile phone has short-term, 30 min, effects on saccard performances [Terao, 2007]. Using 10 normal subjects (4 male, 6 female, with 33.1}8.6 years (23-52 years), they studied the performance of visulally guided saccarde (VGS), gap saccade (GAP), and memory guided saccade (MGS) tasks before and after exposure to 800 MHz EMF with 0.054}0.02 W/kg of 10 g. They also implemented a hand reaction time (RT) task in response to a visual signal. In conclusion, Thiry minutes of moble phone exposure has no significant short-term effect on the performance of various saccade tasks, which suggests that the cortical processing for saccades and attention is not affected.
Shirai et al. evaluated the effects of a 2-year exposure to a RF electromagnetic equivalent to that generated by cellular phones on tumor development in the central nervous system (CNS) of rats [Shirai, 2005, 2007]. Pregnant F344 rats were given a single administration of N-ethylnitrosourea (ENU) on gestational day 18. A 1.439 GHz time division multiple access (TDMA) signal for the Personal Digital Cellular (PDC), Japanese standard cellular system was used for the exposure of the rat head starting from 5 weeks of age, 90 min a day, 5 days a week, for 104 weeks [Shirai, 2005]. A 1.95 GHz wide-band code division multiple access (W-CDMA) signal for the International Mobile Telecommunication 2000 (IMT-2000) cellular system was also employed [Shirai, 2007]. Under the present experimental conditions, exposure of heads of rats to both RF electromagnetic field signals for a 2-year period was not demonstrated to accelerate or otherwise affect ENU-initiated brain tumorigenesis.
Jia et al. monitored local temperature changes in rabbit pinnae, which were evoked by RF electromagnetic field for 20 min at local SAR levels of 0 (sham exposure), 2.3, 10.0, and 34.3 W/kg over 1.0 g rabbit ear tissue [Jia, 2007]. The effects of exposure RF electromagnetic field on skin temperature were measured under normal blood flow and without blood flow in the ear. The results showed: (1) blood flow clearly modified the RF electromagnetic field-induced thermal elevation in the pinna as blood flow significantly suppressed temperature increases even at 34.3 W/kg; (2) under normal blood flow conditions, exposures at 2.3 and 10.0 W/kg, approximating existing safety limits for the general public (2 W/kg) and occupational exposure (10 W/kg), did not induce significant temperature rises in the rabbit ear. However, 2.3 W/kg induced local skin temperature elevation under no blood flow conditions. These results demonstrate that the effects of blood flow should be considered when extrapolating modeling data to living animals, and particular caution is needed when interpreting the results of modeling studies that do not include blood flow.
Masuda et al. examined the influence of RF electromagnetic field on rat skin using Global System for Mobile Communication (GSM)-900 or -1800 Radio Frequency Radiation (RFR) [Masuda, 2007a]. Hairless female rats were exposed or sham-exposed for 2 h to GSM-900 or -1800 signals, using a loop-antenna located on the right part of the rats' back. The local SAR at skin level was 5 W/kg. A skin biopsy was done at the end of the experiment not only at the location of exposure, but also on the symmetrical part of the back. Analysis of skin sections using hematoxylin eosin saffron (HES) coloration showed no difference in skin thickness or apparent cell toxicity among the animal groups. Histological analysis of the epidermis showed that the ratio between cells expressing the antigen Ki-67 (cellular proliferation marker) and the total number of cells remained within the range of normal proliferation ratio for the exposed side of the animal. No Ki-67 labelling was observed at the dermis level. Results on filaggrin, collagen and elastin levels also showed an insignificant influence of RFR. These results do not demonstrate any major physical and histological variations at skin level induced by RFR used in mobile telephony.
Masuda et al. further investigated the effects of RF electromagnetic field on cerebral microcirculation in rat brain [Masuda, 2007bc]. The head of the rat was exposed for 10 min to 1439 MHz RF electromagnetic field at 0.6, 2.4 and 4.8 W/kg of brain averaged SAR [Masuda, 2007b], and for 4 weeks (60 min/day, 5 days/week) to RF electromagnetic field at 2.4 W/kg of brain averaged SAR [Masuda, 2007c]. Four microcirculatory parameters (BBB permeability, leukocyte behavior, plasma velocity, and vessel diameter) were measured before and after RF electromagnetic field exposure using a closed cranial window method. No extravasation of intravenously injected dyes from pial venules was found at any SAR level. No significant changes in the number of endothelial-adhering leukocytes after exposure were found. The hemodynamics indicated that the plasma velocities and vessel diameters remained constant within the physiological range throughout each exposure. These findings suggest that there were no effects on the cerebral microcirculation under the given RF electromagnetic field exposure conditions.
Ushiyama et al. investigated the effect on Blood Cerebrospinal fluid Barrier (BCB) function of rat by RF electromagnetic fields exposure [Ushiyama, 2007]. They set up a real-time measuring system for BCB function using a micro-perfusion method. After the short time exposure (30 min), 1.5 GHz RF electromagnetic field at the brain average SARs of 9.5 W/kg for adult and 10.4 W/kg for juvenile did not affedct BCB function in rats.
The uncertainty of a large-scale long-term in vivo study on brain tumor has been evaluated by Wang et al. and Wake et al. [Wang 2006d 2006e: Wake, 2007a]. They found that the uncertainty of brain SAR in the rats in the exposure setup is higher for male rats than for female rats. Wake et al. developed an exposure setup for local exposure of a rabbit eye in order to evaluate the threshold of ocular effects such as cataract at 2.45 GHz [Wake, 2007b].
K1.5.2 In Vitro Studies
Wang et al. examined the effects of 2450 MHz RF electromagnetic field on malignant changes in mouse C3H10T1/2 cells [Wang, 2005a]. The cells were exposed to the RF electromagnetic field alone in SAR from 5 to 200 W/kg for 2 h and/or were treated with a known initiating chemical, methylcholanthrene (MC) (2.5 Êg/ml). No significant differences were observed in the malignant transformation frequency between the controls and RF electromagnetic field with or without 12-O- tetra decanoylphorbol-13-acetate (TPA) (0.5 ng/ml), a tumor promoter that could enhance transformation frequency initiated by MC in multistage carcinogenesis. However, the transformation frequency for RF electromagnetic field in SAR of more than 100 W/kg with MC or MC plus TPA was increased compared with MC alone or MC plus TPA. In contrast, the corresponding heat groups (heat alone, heat + MC, and heat + MC + TPA) did not increase transformation compared with each control level. The results suggest that 2450 MHz RF electromagnetic field could not contribute to the initiation stage of tumor formation, but it may contribute to the promotion stage in very high SAR (>100 W/kg).
Wang et al. further investigated the effects of 2450 MHz RF electromagnetic field on a stress response in A172 cells, using heat shock proteins (HSP)70 and HSP27 as stress markers [Wang, 2006b]. The cells were exposed to the RF electromagnetic field with a wide range of SAR (5-200 W/kg) or sham conditions. Since the RF electromagnetic field in 50-200 W/kg SAR causes temperature increases in culture medium, appropriate heat control groups (38-44 C) were also included. The results showed that the expression of HSP70 increased in a time and dose-dependent manner in >50 W/kg SAR for 1-3 h. A similar effect was also observed in corresponding heat controls. There was no significant change in HSP27 expression caused by RF electromagnetic field at 5-200 W/kg or by comparable heating for 1-3 h. However, HSP27 phosphorylation increased transiently at 100 and 200 W/kg to a greater extent than at 40-44C. Phosphorylation of HSP27 reached a maximum after 1 h exposure at 100 W/kg RF electromagnetic field. The results suggest that exposure to a RF electromagnetic field has little or no apparent effect on HSP70 and HSP27 expression, but it may induce a transient increase in HSP27 phosphorylation in A172 cells in very high SAR (>100 W/kg).
Komatsubara et al. investigated the effects of RF electromagnetic field on chromosomal aberrations in mouse m5S cells [Komatsubara 2005a]. The RF electromagnetic field exposure was performed at 2.45 GHz for 2 h at average SAR of 5-100 W/kg with continuous wave-form (CW), or at a mean SAR of 100 W/kg (with a maximum of 900 W/kg) with pulse wave-form (PW). The effects of RF electromagnetic field exposure were compared with those in sham-exposed controls and with mitomycin C (MMC) or X-ray treatment as positive controls. No significant differences were observed following exposure to RF electromagnetic field in SAR from 5 to 100 W/kg CW and at a mean SAR of 100 W/kg PW compared with sham-exposed controls, whereas treatments with MMC and X-rays increased the frequency of chromatid-type and chromosome-type aberrations. RF electromagnetic field exposures at 2.45 GHz for 2 h with up to 100 W/kg SAR CW and an average 100 W/kg PW do not induce chromosomal aberrations in m5S cells. Furthermore, there was no difference between exposures to CW and PW RF electromagnetic field.
Takashima et al. examined the effects of 2.45 GHz RF electromagnetic field with SAR from 0.05 to 1500 W/kg in vitro [Takashima, 2006]. When cells (CHO-K1 and MO54) were exposed to a continuous RF electromagnetic field in SAR from 0.05 to 100 W/kg for 2 h, cellular growth rate, survival, and cell cycle distribution were not affected. At 200 W/kg, the cell growth rate was suppressed and cell survival decreased. When the cells were exposed to an intermittent RF electromagnetic field at 300 W/kg (pk), 900 W/kg (pk) and 1500 W/kg (pk) (100 W/kg [mean]), no significant differences were observed between these conditions and intermittent wave exposure at 100 W/kg. When cells were exposed to a SAR of 50 W/kg for 2 h, the temperature of the medium around cells rose to 39.1C, 100 W/kg exposure increased the temperature to 41.0C, and 200 W/kg exposure increased the temperature to 44.1C. Exposure to RF electromagnetic field results in heating of the medium, and the thermal effect depends on the mean SAR. Hence, these results suggest that the proliferation disorder is caused by the thermal effect.
Koyama et al. investigated the effects of 2.45 GHz RF electromagnetic field on bacterial mutations and the HPRT gene mutations [Koyama, 2007b]. Bacteria were exposed to RF electromagnetic field for 30 min in SAR from 5 to 200 W/kg. In all strains, there was no significant difference in the frequency of revertant colonies between sham exposure and RF electromagnetic field-exposed groups. In examination of mutations of the HPRT gene, CHO-K1 cells were exposed to RF electromagnetic field for 2 h in SAR from 5 to 200 W/kg. A combination effect of simultaneous exposure to RF electromagnetic field and bleomycin was detected at the respective SAR. A statistically significant difference was observed between the cells exposed to RF electromagnetic field at the SAR of 200 W/kg. Cells treated with the combination of RF electromagnetic field in SAR from 50 to 200 W/kg and bleomycin exhibited increased HPRT mutations. As the exposure to RF electromagnetic field induced an increase in temperature, these increases of mutation frequency may be a result of activation of bleomycin by a thermal effect.
Sakuma et al. conducted a large-scale in vitro study focused on the effects of RF electromagnetic field from mobile radio base stations employing the IMT-2000 cellular system [Sakuma, 2006]. First, they evaluated the responses of human cells to microwave exposure at a SAR of 80 mW/kg, which corresponds to the limit of the average whole body SAR for general public exposure defined as a basic restriction in the ICNIRP guidelines. Second, they investigated whether continuous wave (CW) and Wideband Code Division Multiple Access (W-CDMA) modulated signal RF electromagnetic field at 2.1425 GHz induced different levels of DNA damage. Human glioblastoma A172 cells and normal human IMR-90 fibroblasts were exposed to RF electromagnetic field. A172 cells were exposed to W-CDMA radiation at SARs of 80, 250, and 800 mW/kg and CW radiation at 80 mW/kg for 2 and 24 h, while IMR-90 cells were exposed to both W-CDMA and CW radiations at a SAR of 80 mW/kg for the same time periods. Under the same RF electromagnetic field exposure conditions, no significant differences in the DNA strand breaks were observed between the test groups and the sham-exposed control groups. These results confirm that low level exposures do not act as a genotoxicant up to a SAR of 800 mW/kg.
Hirose et al. investigated the effects of RF electromagnetic field on apoptosis or other cellular stress response through p53 activation or the p53-signaling pathway [Hirose, 2006]. Under the RF electromagnetic field conditions described above (IMT-2000), no significant differences in the percentage of apoptotic cells were observed between the test groups and the sham-exposed control groups. No significant differences in expression levels of phosphorylated p53 at serine 15 or total p53 were observed between the test groups and the sham-exposed control groups. Moreover, there were no noticeable differences in gene expression of the subsequent downstream targets of p53 signaling involved in apoptosis between the test groups and the sham-exposed control groups. These results confirm that RF electromagnetic field up to 800 mW/kg does not induce p53-dependent apoptosis, DNA damage, or other stress response in human cells.
Hirose et al. further examined the effects of RF electromagnetic field on phosphorylation and overexpression of a heat shock protein HSP27 [Hirose, 2007]. Under the RF field exposure conditions described above (IMT-2000), no significant differences in the expression levels of phosphorylated HSP27 at serine 82 (HSP27 [pS82]) were observed between the test groups and the sham-exposed control groups. Moreover, no noticeable differences in the gene expression of hsps were observed between the test groups and the sham-exposed control groups. These results confirm that e RF electromagnetic field up to 800 mW/kg does not induce phosphorylation of HSP27 or expression of hsp gene family.
Using of human glioma MO54 cells, Miyakoshi et al. investigated whether radio frequency field exposure (1950 MHz with SAR of 1, 2 and 10 W/kg) could activate stress response genes [Moyakoshi, 2005b]. After the exposure up to 2 h, cell growth and cell number were counted at 0-4 days after exposure. Expression of HSP27, HSP70 and the level of phoshorylated HSP27 (78Ser) protein were determined. The results suggested that although exposure to a 1950 MHz RF electromagnetic field has no effect on cell proliferation and expression of HSP27 and HSP70, it may inhibit the phosphorylation of HSP27 at Serine 78 in MO54 cells.
Hikage et al. performed in vitro experiments on free radical production due to 900 MHz and 2.45 GHz mobile radio wave exposure [Hikage, 2006, 2007b]. Using of human white blood cell exposed to 900 MHz RF electromagnetic field, they investigated the estimation of hydroxyl free radical production due to non-thermal effects. Including 900MHz wave, the six different sets of exposure conditions were used: 1) continouse wave, 2) pulse modulation, 3) GSM (Global System for Mobile Communication) basic signal modulation, 4) PDC (Personal Digital Cellular) signal modulation and 5) CDMA (Code Divison Multiple Access) 2000 signal modulation. The exposure level can be changed from cellular level to high SAR level (up to 150 W/kg). The cellfs temperatures were kept below 39 . The experimental data confirms that there is no statistically significant influence of 900 MHz RF electromagnetic field exposure on human white blood cells and that there is a correlation between radical production and cell temperature. In addition, Hikage et al. tried to confirm the effects of 900 MHz and 2.45 GHz RF electromagnetic field exposures on the production of free radical in human fibroblasts cells.
K1.5.3 Other Studies
There have been increased in the number of cellular phone users. With increasing there have been many reports of health disorders related to RF electromagnetic fields. Kawasaki et al. considered and confirmed the dependency of students (Thai university and high school) on cellular phones and compared the results with the dependency of Japanese students (University and high school) [Kawasaki, 2006]. A survey form (cellular phone dependence questionnaire; CPDQ) was distributed to 181 female and 177 male Thai university students and to 240 female and 140 male Thai high school students. Aftere factor analysis, the total scores for the Thai university was higher than the scores for the Thai high school students. The total socre of the questionnaire was high, indicating a strong tendency toward cellular phone dependence.
Due to the
rapid increase of cellular phone use in
K2 Field measurement, Dosimetry and Exposure Asessment
K2.1 DC and ELF Fields
Moriyama et al. assessed ELF magnetic field originating from equipment used for assisted reproduction, umbilical cord-blood and peripheral-blood stem cell transplantation, transfusion, and hemodialysis [Moriyama, 2005a]. The ELF magnetic field values were 0.1-1.2 ÊT on clean benches, <0.1-8.0 ÊT on inverted microscopes, <0.1-13.6 ÊT in CO2 incubators, 4.3-11.5 ÊT in centrifuges, 0.4-18.8 ÊT in programmed freezers, <0.1-0.3 ÊT in deep freezers, 0.3-3.1 ÊT on cell separators, and 0.2-0.9 ÊT in hemodialysers. Frequencies of ELF magnetic field were nominally 60 Hz, but some devices showed non-sinusoidal 120 Hz. Such ELF magnetic field can be reduced by shielding the sources or altering the protocols employed.
Moriyama et al. measured ELF magnetic field at 696 points in a room of a typical Japanese apartment building [Moriyama, 2005b]. ELF magnetic field exceeded 0.4 ÊT in 24 % of the living space, and the maximum value, 1.8 ÊT, was detected at floor level. Analysis of the ELF magnetic field distribution revealed that 60 Hz 100 V electrical wiring for room lights within the floor and ceiling had been laid out in large rectangles, equivalent to 1 turn coils. Further plotting of the vertical components every 0.01 m on the floor indicated that the depth of the cable was 0.23 m. Further studies should be conducted in order to confirm that the building investigated in this pilot study is typical of Japanese apartment buildings in terms of ELF magnetic field.
Kabuto et al. evaluated the effects of
residential power-frequency ELF magnetic field as a possible human carcinogen
by the International Agency for Research on Cancer (IARC) [Kabuto, 2006]. In
response to great public concern, the World Health Organization (WHO) urged
that further epidemiologic studies should be conducted in high-exposure areas
Yamazaki et al. examined the association between residential proximity to 60 Hz high voltage (22-500 kV) overhead transmission lines (HVOTL) and mental health [Yamazaki, 2006]. The prevalence of poor mental health was 15 %. Among the 223 subjects, 10 lived within 100 m of a HVOTL. The adjusted odds ratios (OR) for poor mental health among those who lived 101-300 m or within 100 m from HVOTL were 1.29 (95 % confidence interval (CI): 0.35-10.13) and 1.87 (95 % CI: 0.35-10.13), respectively, against the reference category (>300 m). Mental health status was not significantly associated with the distance between the subject's residence and the closest HVOTL.
Hamada presented a fast-multpile surface-charge-simulation method for calculating three-dimentional Laplacian fields in voxel models. This method treats a surface of a voxel that has different inside and outside conductivities as a surface element of the indirect boundary element method [Hamada, 2006]. This method was successfully applied to calculate the electric field induced by an applied homogeneous EMF magnetic field in a human head model that has 1 m x 1 m x 1 m voxel size.
Kitano et al. formulated mathematically the induced electric field in a spherical conductor exposed to arbital EMF dople magnetic field source [Kitano, 2006]. They confirmed its validity by comparing the analytical solution with numerical solution by the equivalent multiple moment method.
Kobayashi et al. carried out the rejection of magnetic noise from the wire in magnetocardiogram (MCG) measurement [Kobayashi, 2005]. MCG were measured from two subjects with and without attachment of the wire. In order to reduce the effects of magnetic noise from the wire, signal orocessing by independent component analysis, digital-high-pass filter, and singer value decomposition was carried out. Due to the reduction of the magnetic noise from the wire by independent component analysis, independent component analysis is the effective technique.
Miyata et al. proposed the free scanning method for the magnetic field distribution measurements by recording the position of the moved sensor automatically [Miyata, 2007]. The magnetic field sensor has two kinds of range of the measurement frequency, low frequency (30 Hz to 1 kHz) and high frequency (1 kHz to 100 kHz). In their study, they tried to measure two dimensional magnetic flux density distributions in the vicinity of the induction heating (IH) cooker.
Oikawa et al. measured the environmental magnetic field of 50 Hz and 60 Hz in the room very close to power-receiving and transformer rooms in two buildings [Oikawa, 2006].
In highly non-uniform ELF magnetic field, the compliance test in accordance with guidelines has been a crtical issue. When the measured maximum magnetic fields on the surface of the human body exceed the reference level, the basic restriction should be investigated in a different way. Yamazaki et al. proposed a new simplified method for the estimation of the maximum induced current from magnetic field measurements in practical complex [Yamazaki, 2005, 2007]. The method is based on the reduction rate of the magnetic field within a spherical model.The relationship between the reduction rate of magnetic field and the rate of maximum induced current to that of uniform field exposure was approximated using a simple regression curve. The results have practical values for assessing compliance with guidelines.
Nishizawa et al. investigated the magnetic field properties and dosimetry at 50 Hz, ELF with the coil model [Nishizawa, 2007]. This coil model is prescribed as substitute source model fro real household appliances in European standard EN50366 (CENELEC). The accuracy of the magnetic field vectors and the values of the induced current density were compared with the results of two test appliances (a drill machine and a hand mixer) obtained from the equivalent source model. The magnetic fields obtained using the coil model and real appliance show an agreement with each other with a maximum difference of 5 dB. The calculated induced current densities in the numerical human body models (homogeneous and anatomical body models) and the real appliances also show a good agreement with each other with a maximum difference by a factor of 1.6. Based on the totally obtained results in this study, the applicability of the coil model prescribed in EN50366 confirms that of the two applied test appliances.
Takuma et al. reviewed and summarized the recent developed topics related the basic formulas for field calculation, effects of electromagnetic fields, calculation methods, activity of Investigation Committte in the IEEJ, and future research subjects [Takuma, 2006].
K2.2 IF Magnetic Field
Yamazaki et al. developed IF magnetic field exposure facility for in vivo exposure experiment with small animal [Yamazaki, 2006a, 2006b]. Before constructing facility, they first, investigated the effect of architectural structure on the uniform magnetic field generated from their proposed coils by the 3D magnetic field analysis. It is shown that the distance between coil and architectural structure in the direction of magnetic field should be determined taking into account the frequency. Also, the architectural structure has shielding effect. IF magnetic field generates the eddy current inside the reinforcing steel bar, so, the magnetic field disturbance is substantially greater in reinforced concrete building. After these preliminary considerations, Shigemitsu et al. have developed a 20 kHz (IF) magnetic field exposure system for in vivo studies [Shigemitsu, 2007]. The dimensions of the exposure system are 1.6 m x 1.6 m x 1.616 m high located in the specific pathogen free (SPF) exposure room. The system is designed to provide magnetic fields with vertically polarized sinusoidal 20 kHz wave form up to 200 ÊT with the uniformity within }5 % over the space occupied by an animals.
Fujita et al. have developed an IF magnetic field exposure system in vitro [Fujita, 2007]. This system mainly consists of an IF magnetic field generating coil housed inside an incubator, inside which cultured cells can be exposed to IF magnetic field. Two systems were prepared to allow the experiment to be conducted in a double-blind manner. The level of the generated IF magnetic field was set to 532 ÊT rms in the exposure space, 23 kHz, 80 times the value in the International Commission on Non-ionizing Radiation Protection (ICNIRP) guidelines, with spatial field uniformity better than 3.8 %. The waveforms were nearly sinusoidal. The parasitic electric field was 157 V/m rms and the induced electric field was 1.9 V/m rms. The temperature was maintained at 36.5 } 0.5 C for 2 h. The leaked magnetic flux density was 0.7 mT rms or lower in the stopped system when the other system was being operated, and the environmental magnetic flux density was 0.1 mT rms or lower. This system could be successfully used to evaluate the biological effects of exposure to IF magnetic field.
Kamimura et al. evaluated the magnetic field exposure of human body near an induction heating (IH) cooker with 20 kHz by using of SPFD method [Kamimura, 2006]. They calculated the maximum induced current density among thee kinds of human body models (Japanese adult male/female and American adult male) and compared the calculated current density with the guideline of ICNIRP. They showed that the maximum induced current densities are different among three models. They also showed that the induced current exceeding the guideline of ICNIRP may not flow inside human body in the case with a portable type IH cooker and a pan designed for the IH cooker.
Nishizawa et al. investigated the magnetic field properties and dosimetry at 21 kHz, intermediate frequency for an induction heater (IH) with the coil model [Nishizawa, 2006]. This coil model is prescribed as substitute source model in European standard EN50366 (CENELEC). The accuracy of the magnetic field vectors and the values of the induced current density were compared with the results of realistic model for IH obtained from the equivalent source model. The coil model coincided well for the magnitude of the magnetic field strength around the IH. On the other hand, the dominant field vector of the coil model differs significantly from the real IH, which leads to induced current densities in the body model, three times larger. These results showed that the application of the coil model prescribed in the EN50366 is confirmed for the IH.
Suzuki and Taki measured the magnetic field around induction heating hobs operated at 20 kHz and evaluated the compliance with ICNIRP guideline [Suzuki, 2005]. At the very proximity to the device, the distribution of the magnetic flux density was highly inhomogeneous and the maximum flux density can exceed the reference levels of the guideline. Using of anatomical human model, the induced current densities exposed to magnetic field were calculated numerically by impedance method. The induced current densities were sufficiently lower than the basic restriction of INCIRP guideline.
Tarao et al. calculated the induced current in an anatomiccaly high-resolution human model exposed to 20.9 kHz operated house-hold (IH) induction cooker [Tarao, 2006ab]. In case of the adult human model exposed to highly inhomogeneous 20.9 kHz magnetic field, they calculated that the induced current ranging from 5 to 19 mA/m2 is obtained for between the shoulder and lower abdomen. However, for child model, it can be obtained that the currents between 5 and 21 mA/m2 are induced for between the head and abdomen. They also obtained the result that the induced current in the child model are 2.1 to 6.9 times larger compared of the adult model under the exposure condition. They further studied the induced current in an anatomically human model of 2.5 x 2.5 x 2 mm voxel size exposed to 20.9 kHz magnetic fields generated from IH cooker by impedande method. In calculation, the maximum about 2 ÊT magnetic field near the lower abdomen of the body was assumed. ICNIRP guideline gives that the basic restriction is expressed in term of a current densities averaged over a cross-section of 1 cm2 perpendicular to the direction of the current. Tarao et al. proposed the conversion of computed results to corresponding current densities by averaging the current over the cross section of any 1 cm2 of the model. The calculation results showed that the maximum averaged current densities, 5.31 mA/m2 appears at the muscle of the abdomen, close to the magnetic sources. This value is 1/8 of the ICNIRP basic restriction level for the public exposure. In calculation at certain voxel, the averaging is key procedure. For example, the maximum value with the averaging decreased by 60 % from 13.2 mA/m2 without the averaging to 4.31 mA/m2.
Induction heating (IH) cooker is
recently very popular in
K2.3 Radio frequency electromagnetic fields and Microwaves
Wang et al. reported some detailed dosimetry results for the Salford-used transverse electromagnetic (TEM) cell in rats [Wang, 2006a]. The whole-body average SAR and the brain-average SAR varied up to 1.5 times and 2.7 times, respectively. For an input of 1 W to the TEM cell, the whole-body average SAR was 1.1 W/kg, while the brain-average SAR was 1.0 W/kg. This means that the TEM cell structure obviously produces not a local but a whole body exposure.
Wang et al. evaluated RF electromagnetic field in experimental fusion facilities for safety guidelines to ensure workersf safety [Wang, 2005b]. Since the leaked RF electromagnetic field has time-varying characteristics whose amplitudes vary according to a stochastic process, a measurement of the amplitude probability distribution (APD) was conducted. An approach was then presented to derive from the measured APD and SAR in an exposed human body. The statistically-averaged whole-body-averaged SAR showed that the leaked field intensities were low enough to not cause any thermal hazards for the workers in the specific RF electromagnetic field environment. The statistically averaged SAR also showed fair agreement with the SAR derived from the time average over 6 min as specified in the safety guidelines. This finding suggests the usefulness of the APD measurement in lieu of a field measurement over a 6-min period because the APD can be obtained in a time period much less than 6 min.
Wang et al. made a detailed error analysis in the whole-body average SAR calculation for the finite-difference time-domain (FDTD) method in conjunction with the perfectly matched layer (PML) absorbing boundaries [Wang, 2006b]. They derived a basic rule for the PML employment based on a dielectric sphere and the Mie theory solution. They then attempted to clarify to what extent the whole-body average SAR may reach using an anatomically based Japanese adult model and a scaled child model. The results showed that the whole-body average SAR under the ICNIRP reference level exceeds the basic safety limit nearly 30 % for the child model both in the resonance frequency and 2 GHz band [Wang, 2006c].
Hirata investigated the effect of frequency, polarization, and angle of incidence of an ELF electromagnetic field on the SAR and maximum temperature increase in the human eye at 900 MHz, 1.5 GHz, and 1.9 GHz [Hirata, 2005a]. The SAR and temperature increased in the eye, largely dependent on the separation between the eye and a source, and the frequency, polarization, and angle of incidence of the ELF electromagnetic fields wave. The maximum temperature increased (0.303-0.349 C) in the lens of the adult for the SAR value of 2.0 W/kg for the eye tissue (about 10 g) was marginally affected by the above-mentioned factors. No clear difference of a maximum temperature increase in the lens at the SAR limit was observed between the adult and children models.
Hirata et al. investigated statistically the maximum temperature increases in the head and brain for the SAR averaging schemes prescribed in the ICNIRP and IEEE guidelihnes [Hirata, 2005b]. They paid much attention to the correlation between peak SARs and maximum temperatures. They found that maximum temperature increases iin the head are well correlated with peak spatial average SARs calculated with different schemes. Maximum temperature increases in the head for peak SAR values are largely dependent in the averaging scheme.
Hikage et al. estimated the electromagnetic field exciation by cellular radios in actual train carriages [Hikage, 2005b]. They mentioned; with regard to the electromagnetic compatibility (EMC) of the portable radio terminals such as cellular phones and data communication transceivers, the important issue is to prevent the occurrence of unwanted effects on the human health due to the RF exposure. As example, they conducted the precise computer numerical stimulating, FDTD method, using 800 MHz and 2 GHz transmitter in an actual train carriage and estimated the electromagnetic field distribution excited inside train carriage. The parallel FDTD computer simulation could be considered to be effective for estimating the complicated electromagnetic field excitation problems precisely.
Hikage et al. developed a 900 MHz ridged-waveguide microwave exposure equipment to achieve high power density irradiation for in vitro experiments [Hikage, 2007d]. This exposure system consists of a vector signal generator, 100 watts transistor amplifer, stub tuner, the ridged waveguide and terminator.
Ishikawa and Tanimura visualized the magnetic leakage flux from cellular phone [Ishikawa, 2006]. As a result of the visualization, the magnetic leakage flux from some parts of cellular phones can be clearly observed even when the cellular phone is turned off. The magnetic leakage flux can be estimated roughly to be about 0.01 mT. They emphasized this visualizing technique is usefull for the research areas of human health, environmental medicine, scientific education and engineering.
Although there are several papers on the
evaluation of electromagnetic wave exposure in the fetues, the abdomen model,
of pregnant women, the structure inside the models is not representive of
actual situation due to the organ and tissue complexity of the mother and
fetus. So, Kawai et al. presented a
simple abdomen modcel of pregnant women and evaluated the SAR inside the
proposed model close to normal mode helical antennas (NHAs) [Kawai, 2006]. The
SAR was calculated using FDTD method. They confirmed that the 10-g average SAR
in the fetus is sufficiently less than 2 W/kg, when the output power of NHAs is
5 W which is the maximum power of portable radio terminals in
Nagaoka et al. developed an anatomicazlly realistic whole-body pregnant-woman model for electromagnetic dosimetry [Nagaoka, 2007]. The numerical dosimetry of pregnant women is an important issue in electromagnetic field safety. They constructed a new fetus model including inherent tissues of pregnant women based on abdominal magnetic resonance imaging data of a 26-week-pregnant woman. The whole-body pregnant woman model was developed by combining the fetus model and a nonpregnant-woman model. The modle consists of about 7 million cubical voxels of 2mm size and is segmented into 56 tissues and organs.First, this pregnant-woman model is completely anatomically realistic voxel model that includes a realistic fetus model and enables a numerical simulation of electromagnetic dosimetry up to the gigahertz band. In this paper, the basic specific absorption rate characteristics of the pregnant-woman model exposed to vertically and horizontally polarized electromagnetic waves from 10 MHz to 2 GHz.
With rapid increase in the use of the mobile phones in enclosed environments such as trains and elevators, public concern regarding the possibility of the RF exposure in such areas exceeding the basic restriction of the ICNIRP exposure guideline has been growing. Using of FDTD calculation method, Simba et al. carried out to determine whether the exposure in the elevator can exceed the basic restriction, 0.08 W/kg, whole-body average SAR [Simba, 2007a, 2007b]. They performed the FDTD calculation of the 10 g average SAR as a function of the human body position inside an elevator at 900, 1500 and 2000 MHz. The SAR results are below the ICNIRP exposure guideline.
Wang et al have developed a formulation to approximate complex permittivities of biological tissues and organs as function of age [2006e]. The model is based on the dependence on water-content ratio which is dominant to determine the complex permittivitis in GHz band.
A novel technique to evaluate SAR experimentally has been developed by Suzuki et al. [Suzuki, 2006]. Using liquid crystal sensitive to temperature, they measured temperature elevation due to microwave exposure.
Standardization of procedures for compliance tests of wireless terminals is also one of important topics. Mochizuki et al. clarified the effects of the size and shape of head phantoms on SAR distributions during exposure to near-field from a cellular phones [Mochizuki, 2007]. Ishii et al. investigated on applicability of a small antenna in phantom liquid for calibration of SAR probes [Ishii, 2007].
K3 Tissue Properties, Materials, and Phantoms
K3.1 Design Methods of the Electromagnetic Environment
Tosaka et al. developed a measuring system using a tri-axial search coil in order to measure the magnetic field noise around electric devices [Tosaka, 2005]. They chose the measuring frequency is less than 100 kHz and the sensitivity is of the order of pico Tesla. In conclusion, the crosstalk of the orthogonal search coil is less than -40dB between the tri-axial search coil sensors. The sensitivity of the search coil is 10 pT/ãHz at 1 kHz.
K3.2 Phantoms andTissue Properties-Bioelectromagnetics Parameters
Hirata et al. quantified induced current in anatomically based Japanese male and female models for exposure to low-frequency electric fields [Hirata, 2007b]. A quasi-static FDTD method was applied to analyze this problem. For the computational results, the difference of the induced current density averaged over an area of 1 cm2 between Japanese male and female models was less than 30 % for each nerve tissue. The difference of induced current density between the present study and earlier works was less than 50 % for the same conductivities, despite the different morphology. Particularly, maximum current density in central nerve tissues appeared in the retina of Japanese models, the same as in the earlier works.
Hirata et al. computationally verified the effect of anesthesia on temperature variations in the rabbit eye due to microwave energy [Hirata, 2006a]. The FDTD method was used for calculating the SAR and temperature variation in rabbits. They used a computational rabbit phantom, which is comprised of 12 tissues (including 6 eye tissues) with a resolution of 1 mm. Thermal constants of the rabbit were derived by comparing measured and calculated temperatures. For intense microwave exposure to the rabbit eye, time courses of calculated and measured temperatures were in good agreement for cases both with and without the administration of anesthesia. The point to be stressed is that under anesthesia the thermoregulatory response was inactivated, and blood flow and basal metabolism was reduced.
The correlation between the peak spatial-average SAR and maximum temperature increase for antennas attached to the human trunk was reported [Hirata, 2006b]. Frequency bands considered are 150, 400, and 900 MHz, which are assigned for occupational communications. The effect of variation of thermal constants on the temperature increase is revealed by using one-dimensional model. Computational results suggests that one of the most dominant factors which affect the correlation between peak SAR and maximum temperature increase is blood flow in tissues.
Hirata proposed an improved heat transfer model of the eye for exposure to RF electromagnetic field. Particular attention was paid to the difference from the simplified heat transfer model commonly used in this field [Hirata, 2007a]. From the computational results, the temperature elevation in the eye calculated with the simplified heat transfer model was largely influenced by the RF electromagnetic field-induced SAR outside the eyeball, but not when using their improved model.
Hirata et al. reported that a RF electromagnetic field-induced SAR of the human body for far-field exposure at the International Commission on the ICNIRP reference level has two peaks in the resonance frequency and GHz regions [Hirata, 2007d]. Dominant factors influencing whole-body average SAR in these two frequency regions have not yet been revealed sufficiently. The main purpose of this study is to clarify the dominant factors influencing the SAR in terms of whole-body average SAR in an anatomically based model compared with those in a homogeneous anthropomorphic model and corresponding cuboid models. Computational results show that the SAR peak in the resonance frequency region greatly depends on the electric properties of tissue, while the peak in the GHz region is affected mainly by the surface area of the model.
Hirata et al. investigated the effect of blood temperature variation modeling on body-core temperature [Hirata, 2007c]. The computational results show that the modeling of blood temperature variation was the dominant factor influencing the body-core temperature. This is because the temperature in the inner tissues is elevated via the circulation of blood whose temperature was elevated due to the RF electromagnetic field-induced SAR. Even at different frequencies, the body-core temperature elevation at an identical whole-body average SAR was almost the same, suggesting the effectiveness of the whole-body average SAR as a measure in the ICNIRP guidelines. Next, they discussed the effect of sweating on the temperature elevation and thermal time constant of blood. The variability of temperature elevation caused by the sweating rate was found to be 30%. The blood temperature elevation at the basic restriction in the ICNIRP guidelines of 0.4 W/kg is 0.25C even for a low sweating rate. The thermal time constant of blood temperature elevation was 23 min and 52 min for a man with a lower and a higher sweating rate, respectively, which is longer than the average time of the SAR in the ICNIRP guidelines. Thus, the whole-body average SAR required for blood temperature elevation of 1 C was 4.5 W/kg in the model of a human with the lower sweating coefficients for 60 min exposure. From a comparison of this value with the basic restriction in the ICNIRP guidelines of 0.4 W/kg, the safety factor was 11.
Hirata et al. investigated the temperature elevation in the eye of anatomically based human head models for plane-wave exposures [Hirata, 2007e]. The finite-difference time-domain method is used for analyzing the RF electromagnetic field-induced SAR and temperature elevation. The eyes in the anatomic models have average dimensions and weight. Computational results show that the ratio of maximum temperature in the lens to the eye-average SAR is almost uniform (0.112-0.147C W/kg) in the frequency region below 3 GHz. Above 3 GHz, this ratio increases gradually with an increase of frequency, which is attributed to the penetration depth of RF electromagnetic field. Particular attention is paid to the difference in the heating factor for the lens between this study and earlier works. Considering causes clarified in this study, compensated heating factors in all these studies are found to be in good agreement.
Hirata et al. investigated the SAR and temperature elevation in an anatomically-based human model for RF electromagnetic field exposure [Hirata, 2007f]. First, they investigated the effect of blood temperature variation and thermoregulation modeling on body-core temperature. The modeling of blood temperature variation was found to be the dominant factor influencing the body core temperature. This is because the temperature in the inner tissues is elevated via the circulation of blood warmed due to the RF electromagnetic field-induced SAR. For the same whole-body average SAR at different frequencies, the body-core temperature elevation was almost same, suggesting the effectiveness of the measure used in the ICNIRP guidelines. Then, they discussed the effect of sweating rate on the temperature elevation and thermal time constant of blood temperature. The uncertainty of temperature elevation due to the sweating rate was 30% or so.
Saito and Ito have been studying various coaxial-slot antennas for microwave hyperthermia. Saito et al. presented the effectiveness of the coaxial-slot antenna and the array applicators composed of two or four coaxial-slot antenna through clinical trials [Saito, 2005]. Then, as an example, they have developed a coaxial-slot antennas aiming at intracavitary heating for bile duct carcdinoma [Saito, 2006; Hiroe, 2006]. They estimated the heating performance of such antenna for the actual treatments and confirmed the possibility of this treatment by use of the proposed coaxial-slot antenna.
Phantoms are used to evaluate amounts of absorbed electromagnetic energy. Ito and his research groups developed phantoms for use in the frequency range from 3 to 10 GHz. Takimoto et al. evaluated the effectiveness of the biological tissue-equivalent solid phantom for Ultra WideBand (UWB) communications [Takimoto, 2006]. Solid phantom can be obtained manufactually the arbitrary shapes. Such solid phantom have neen developed and used for the frequency bands between 3-10 GHz It was shown that it is possible to investigate antenna characteristics using this developed phantom in wide frequency ranges in mobile terminal. Ito et al. reviewed the development of solid biological tissue-equivalent phantoms for UWB communications band and evaluated the interaction between human bodies (called biological tissue-equivalent phantom) and radio terminals [Ito, 2007b].
Hiroe et al. developed the phantom for measurement of temperature rises inside biological tissue by electromagnetic wave exposure [Hiroe, 2007]. Iwai et al. also developed a realistic human phantom in a PDA (Personal Digital Assistance) position for electromagnetic wave evaluation of handset antennas [Iwai, 2006].
There are few data of electrical properties of biological tissues and organs in millimeter-wave (MMW) while new wireless technology will be operated in the frequency regions. Wakatsuchi et al. recently tried to measure complex permittivities of whole-blood sample upto 50 GHz [Wakatsuchi, 2007].
K4 Biomedical Applications
K4.1 Magnetic stimulation
Hirayama et al. examined the effects of rTMS on pain in patients with intractable deafferentation pain [Hirayama, 2006]. Twenty patients received ten trains of rTMS (5 Hz for 10 seconds at 50 second interval) of the primary motor cortex (M1), the postcentral gyrus (S1), premotor area (preM), and supplementary motor area (SMA). Results indicated a statistically significant effect lasting for 3 hours after the stimulation of M1. Stimulation of other targets was not effective. The M1 was the sole target for treating intractable pain with rTMS, in spite of the fact that M1, S1, preM, and SMA are located adjacently.
Saitoh et al. also investigated the effects of rTMS on pain in patients with intractable deafferentation pain [Saitoh, 2006, 2007a]. Ten trains of rTMS (5Hz for 10 seconds at 50 second interval) were applied to the M1, S1, preM and SMA. Only M1 stimulation was effective for pain reduction (50%). Motor cortex stimulation (MCS) procedures were performed. The success rate of MCS was around 63%, and seemed to be higher in cases of pain with spinal cord and peripheral origins, while it was lower in cases of post-stroke pain.
Saitoh et al. further evaluated the effects of rTMS on pain in patients with a cerebral lesion or with a noncerebral lesion [Saitoh, 2007b]. Ten trains of rTMS (5Hz for 10 seconds at 50 second interval) were applied to the M1, S1, pre-. The rTMS was applied to all the patients at frequencies of 1, 5, and 10 Hz and as a sham procedure in random order. High-frequency (5 or 10 Hz) rTMS of the precentral gyrus can reduce intractable deafferentation pain, but low-frequency stimulation (at 1 Hz) cannot. Patients with a noncerebral lesion are more suitable candidates for high-frequency rTMS of the precentral gyrus.
Sakihara et al. investigated whether the vestibulospinal tract mediates late electromyographic response with a latency of 100ms evoked bilaterally in soleus muscles following rTMS (1.4 T ELF-PEMF) over the left cerebellum [Sakihara, 2007]. The vestibulospinal tract was activated by optokinetic stimulation. The results show that the latency of the soleus electromyographic response is shortenedby optokinetic stimulation, but the latency of the motor response evoked by the corticospinal tract is unchanged. These findings support our hypothesis that vestibulospinal tracts mediate late electromyographic responses, and allow the development of techniques to assess the human vestibulospinal system function.
Ueno and Sekino reviewed medical applications of the recently developed techniques in biomagnetics and bioimaging such as transcranial magnetic stimulation, magnetoencephalography, magnetic resonance imaging, cancer thrapy based on magnetic stimulation, and magnetic control of cell orientation and cell growth. They emphasized that these techniques are leading medicine and biology into a new horizon through the novel application of magnetism [Ueno, 2006].
First, Sekino et al. calculated eddy current distributions in transcranial magnetic stimulation (TMS) under various conditons and compared ther calculated results with the current distribution in electroconvulsive therapy (ECT) in order to find an optimum conditions of TMS as an alternative to ECT [Sekino, 2005d]. Then, they performed numerical simulation of the eddy current induced by transcranial magnetic stimulation (TMS) to the cerebellum [Sekino, 2006a]. Solutions were obtained on a three-dimensional human head model with inhomogeneous conductivity. The maximum current density in the cerebellum was 2.9A/m2 in a magnetic field intensity of 0.56 T. Distribution of the eddy current in the cerebellum was limited to approximately 1 cm beneath the surface of the cerebellum.
Maeda et al. designed and developed the magnetic separator for biomaterials labeled by magnetic beads [Maeda, 2007]. Magnetic separation is an important method for purifying of cells or NDA. Their developed magnetic separator consisted of three rectangular coils, two circular coils, and a separation chamber. A separation rate over 90 % was obtained with this sytem in a separation test using magnetic beads.
K4.2 Thermal Therapy
Tanaka et al. investigated the therapeutic effects of dendritic cell (DC) therapy combined with magnetite cationic liposomes (MCL)-induced hyperthermia on mouse melanoma [Tanaka, 2005]. In an in vitro study, when immature DC was pulsed with mouse B16 melanoma cells heated at 43C, major histocompatibility complex (MHC) class I/II, costimulatory molecules CD80/CD86 and CCR7 in the DC were upregulated, thus resulting in DC maturation. C57BL/6 mice bearing a melanoma nodule were subjected to combination therapy using hyperthermia and DC immunotherapy in vivo by means of tumor-specific hyperthermia using MCL and directly injected immature DC. Mice were divided into 4 groups: group I (control), group II (hyperthermia), group III (DC therapy) and group IV (hyperthermia + DC therapy). Complete regression of tumors was observed in 60% of mice in group IV, while no tumor regression was seen among mice in the other groups. Increased cytotoxic T lymphocyte and natural killer activity was observed on in vitro cytotoxicity assay using splenocytes in the cured mice treated with combination therapy, and the cured mice rejected a second challenge of B16 melanoma cells. This study has important implications for the application of MCL-induced hyperthermia plus DC therapy in patients with advanced malignancies as a novel cancer therapy.
Mochiki et al. applied a new treatment modality using a combination of gastrectomy with postoperative intraperitoneal hyperthermo-chemotherapy (PIHC) using a heating device Thermotron RF-8 (8 MHz EMF) [Mochiki, 2007]. They evaluated the feasibility of PIHC in advanced gastric carcinoma patients with peritoneal seeding. The PIHC group received a 60-min PIHC with a cisplatin (80 mg/m2) two weeks after surgery, and the control group received surgery alone. The PIHC group had a significantly higher survival rate and better prognosis compared with the control group.
Ito and Saito described two types of heating schemes which can be used with microwave enery, and provided brief explanations of the basic engineering involved [Ito, 2007a]. In addition, they pointed out the evaluation method of antenna performance. Ito reviewed the antenna technology to medicine [Ito, 2006]. His review included the diagnosis, hyperthermia, MRI, computed tomography and telemetering system.
K4.3 Thermal Therapy-Soft heating and Inductive Heating
In hyperthermia, high frequency electromagnetic fields are used to heat the cancer cells. These electromagnetic fields fall into two frequency ranges and produced some side effects such as the heating of healthy cells or the impact on the body of invasive surgery required to exposed deep-lying cells. To reduce these side effects, Matsumoto et al. proposed the use of lower microwave frequencies with phase control [Matsumoto, 2007]. They confirmed that the phase control technique for long-wavelength, 430 MHz, microwaves was effective in producing localized heating. In order to use the brain tumor, Kikuchi et al. estimated the heating pattern for interstitial microwave hyperthermia by a coaxial-dipole antenna [Kikuchi, 2006]
Saito and Ito described the fundamental characteristics of microwave inside the biological tissue and two types of heating schemes for the hyperthermic treatments [Saito, 2007]. In Addition, they introduced the actual treatment of newly developed microwave antenna. Microwave energy is one of the heating sources used for thermal therapy of cancer.
Stents are one method of treatment for stenosis of lumens organ from various causes. The cylindrical metallic stents are composed of alloy wire. After stents are implanted, however, the stenosis may recur due to a tumor or abscess again. It is particularly difficult to remove tumors or abscesses of the bile duct by surgical repair, because the duct is in a deep portion of the abdomen. Oya et al. proposed a noninvasive remedying method for tumors and abscesses by using thermotherapy with magnetically excited metallic stents [Oya, 2006; 2007]. Currently, clinical stents are not manufactured to allow for heating. We made experimental stents by magnetic shunt steel to heat the stents and control the heat of stents by external magnetic excitation for thermo-therapeutic applications [Hodaka, 2005].
A series of research papers about the soft-heating from
Takura et al. created a complex heater composed of thermosensitive ferrite wound on a metallic ring which produces a greater amount of heat due to losses through hysteresis and inductive current than thermosensitive ferrite alone [Takura, 2007a]. The temperature of the heater was controlled by using the Curie-point. They comment that it is necessary to miniaturize the element and achieve optimal performance if their technique is used. They also developed the miniaturization of micro implantable devices with thermosensitive ferrite for soft-heating hyperthermia [Takura, 2007b].
K4.4 MRI and Current Distribution MRI
Two strategies-motor and visual- are considered to be used for performing mental rotation. The former involves the function of the motor-related areas of the brain, whereas the latter does not. Subjectfs experience influence strategy selection during the mental rotation of three-dimensional (3D) shapes. However, it remains questionable as to whether the attributes of 3D objects enhace the motor-related activities. Kawamichi et al. compared the brain activities during two types of mental rotations-two-dimensional (2D) and 3D rotation using functional magnetic resonance imaging (fMRI) [Kawamichi, 2007a]. Then, they measured spatio-temporal brain activities during two types (two dimensional (2D) and 3D rotation tasks) of mental rotation of 3D objects using magnetoencephalography (MEG), task difficulty enhanced by rotation dimensionality is a major factor related to the selection of motor strategy [Kawamichi, 2007b].
Sekino et al. performed numerical simulations of the eddy current induced by TMS/ELF-PEMF to the cerebellum [Sekino, 2006a]. Solutions were obtained on a three-dimensional human head model with inhomogeneous conductivity. The stimulating coil consisted of a pair of circular coil elements with a diameter of 110 mm. The electric current applied to the coil had an intensity of 44.2 kA Turn, which resulted in a magnetic field intensity of 0.56 T at the center of a coil element. The maximum current density in the cerebellum was 2.9 A/m2. Distribution of the eddy current in the cerebellum was limited to approximately 1 cm beneath the surface of the cerebellum. The eddy current had a localized distribution in the cerebellum, while the magnetic field had a broad distribution.
Detection of weak magnetic fields induced by electrical currents using MRI is necessary for mapping neuronal activities in the brain. Such detection is dependent on the signal-to noise ratio and sensivitiy of MRI. Hatada et al. computed the brain eddy current distributions induced by RF magnetic field from a birdcage coil in MRI by simulations based on the finite element method (FEM) and calculated Johnson noise from the head [Hatada, 2005a, 2005b].
Imae et al. obtained the minimization of discrete errors in diffusion simulation of nuclear magnetization [Imae, 2007]. Simulations of finite-difference diffusion are used for solving the diffusion equation of nuclear magnetization in discrete space and time. They evaluated the difference between a discrete solution and an exact solution that had been derived from the manetization diffusion equation..
Tanaka et al. proposed a method of estimating mechanical strain in biological tissue using diffusion MRI [Tanaka, 2007]. Mechanical strain in biological tissues causes a change in the diffusion properties of water molecules. Measurements were carried out on uncompressed and compressed chicken skeletal muscles. A theoretical model of the diffusion of water molecules in muscle fibers was derived based on Tannerfs equation. The intracedllualr duffusion coefficient was changed by mechanical strain.
Kodama and Takeuchi assessed relationships between six texture features and changes in atrophy of the cerebral parenchyma, the hippocampus, and the parahippocampal gyrus in the Alzheimer-type dementia (ATD) brain to determine whether or not the features reflect cerebral atrophy in ATD patients [Kodama, 2005]. The subjects were 10 ATD patients consisted of three men and seven women (the mean age of 71.4}6.7 years) underwent an MRI test of the head annually for at least 3 consecutive years. These results indicate that the six texture features were shown to reflect gray matter atrophy associated with ATD and to change with the progress of the disease. The texture features should be a more effective instrument for identifying the progress of ATD.
Kumagai et al. prepared PEG-coated beta-FeOOH nanoparticles through electrostatic complex formation of iron oxide nanoparticles with poly (ethylene glycol0-poly (aspartic acid) block copolymer [PEG-P (Asp)] in distilled water [Kumagai, 2007]. The nanoparticle size was determined to be 70 nm with narrow distribution. The PEG-coated nanoparticles revealed excellent solubility and stability in aqueous solution as well as in physiological solution. The experiments on tumor-bearing mice demonstrated that this nanoparticle achieved an appreciable accumulation into solid tumor.
Using of Wistar rats at nine weeks olds, Saotome et al. obtained 1H magnetic resonance spectra of skeletal muscles, with and without atrophy and evaluated the content of creatine in the muscles [Saotome, 2005]. Tissues have diffusional anisotropy. Their diffusion properties are denoted by a tensor. Saotome et al. evaluated the diffusional anisotropy and microscopic structure in atrophied skeletal muscles using the pulsed-gradient spin-echo (PGSE) nuclear magnetic resonance (NMR) method [Saotome, 2006]. In this study, the left sciatic nerve was severed in twelve 9-week-old rats. The proposed method is effective for evaluating changes in the microscopic structure of skeletal muscles.
Sekino et al. obtained the spatial distribution of anisotropic conductivity of the human brain using MRI [Sekino, 2005a]. Estimaiton of conductivity is based on the proportionality between the conductivity and the diffusion coefficient of water. The gray matter did not have a clear dependence of conductivity on direction. In some rejoin in the white matter, conductivity exhibited high anisotropy. This method has potential applications in current source estimations of EEG and MEG. Then, Sekino et al. investigated the effect of strain on diffusion tensor MRIs of muscles using numerical simulations and animal experiments [Sekino, 2005b]. A compression of a tissue caused a decrease in the effective coefficient in the direction of compression and an increase in the fractional anisoptropy of diffusion.
Generally, non-invasive imaging techniques is usefull for analysis of electromagnetic fields, current distributions in electric stimulation and magnetic stimulation, the calculation of the absorption of electromagnetic waves from mobile phones, current source estimation in EEG andc MEG. Sekino and Ueno reviewed the new methods for MRI of electric properties in living bodies [Sekino, 2007]. They recommend that new methods have potential applications in biomedical engineering involving electromagnetic field analysis and new diagnostic imaging techniques.
K4.5 Contactless power transmission system
Matsuki and Sato explain the fundamental operation of circuit, and outlines trends in circuits for various contactless power supply application including home electrical appliances and electric automobiles [Matsuki, 2007].
Contactless power supply systems transit electric power by electromagnetic induction with a pair of coils. The efficiency and the output voltage depend on parameters of coils. The suitable parameter values that realize stable high efficiency contactless power supply have been obtained. In the application with low output voltage, the voltage drop of he diodes becomes dominant power loss. A synchronous rectification was proposed as a solution of this problem. The contactless power supply system for an artificial heart operates at 190 kHz. The planar coils with Mn-Zn ferrite course were applied. Highly stable output voltage and 93.4% of maximal efficiency (dc-dc) were realized.
The devices were designed in view of the biomedical compatibility, gradually sloped coils and the flexibility of the primary coil prevent pressure necroses of the skin. The rectifier circuit board was placed in the internal space of the ferrite core to reduce the number of the implanted devices.
Implant medical devices are physically isolated from power sources required to supply driving energy to them. A well-known contactless power transmission technology is the transcutaneous energy transmission system (TETS), which applies electromagnetic induction between two disk-like spiral coils (a primary coil outside the body, and a secondary coil inside the body). Implant devices that require a temperature rise for their actuation must be prevented from overheating, and transcutaneous control and monitoring of the devices7 temperature is necessary. A small inductor with a thermosensitive ferrite core was developed as a thermo-sensing device. This inductor controls the temperature automatically inside the body in combination with TETS. A coupling factor change between the two coils of a TETS transformer also affects the stability of power transmission characteristics. A suitable excitation frequency was designed to ensure stable driving. The control system referred to above has been applied in an artificial anal sphincter system that is now being developed, and appropriate driving has been observed [Arai, 2005; Kakubari, 2006a, 2006b; Matsuki, 2007; Miura, 2005a, 2005b, 2006].
K4.6 Electromagnetic interference
The use of implantable
cardiac pacemakers has become more widespread in the world. In
Hanada proposed that most problems with the electromagnetic environment of medical institutions have been related to radiated electromagnetic field and have been constructed from reports about electromagnetic interference (EMI) with electronic medical equipment by the radio waves emitted from mobile telephone handsets [Hanada, 2007]. Examples of measurements and measuring methods were shown for radiated electromagnetic field, the static magnetic field, power-source noise, and common components of the medical electromagnetic environment.
Tarusawa et al. clarified the impact of electromagnetic interference (EMI) from cellular base station (BS) antennas on implantable cardiac pacemaker [Tarusawa, 2005b]. The estimation of the impact is based on in vitro experiments conducted using simulated multicarrier and multicode signals. These signals are transmitted from actual BS antennas and dipole antennas as the radiation source of the BS antenna. The results showed that pacemaker EMI depends on the average power of the transmission signal and does not depend on the peak-to-average power ratios of the transmission signals. No pacemaker EMI is detected in the immediate vicinity under the BS antenna at an input power level for typical operation. It is clear that the pacemaker EMI should not pose a concern in residential environments.
Futatsumori et al. investigated the the EMI effect of RFID reader/writer on pacemakers and ICDs using newly constructed in vitro experimental system based on an Irnichfs flat torso phantom [Futatsumori, 2006abcd]. The in vitro EMI test, experiments on 10 types of RFID reader/writer and 13 types of implantable pacemakers and defibrillators were conducted. The frequency bands were 125 kHz, HF (13.56 MHz), UHF (950 MHz) and 2.45 GHz. Futatsumori et al. have been carried out the detailed in-vitro experiments to assess the EMI due to RFID reader/writers for implantable medical devices (RFID/IMD-EMI). They proposed a novel RFID/IMD-EMI assessment methodology based on the total magnetic flux integrated across the pacemaker and the lead cross-section [Futatsumori, 2007ab]. Taguchi et al. developed three-dimensional automatic mearuement system for the assessment methodology of implantable medical devices EMI due to RFID reader/writers [Taguchi, 2007].
Hikage et al. estimated the EMI risk to pacemakers by cellular radio transmission considering of the effect of electromagnetic field absorption and shielding due to a humanfs body inside the elevator [Hikage, 2007a]. Large scale FDTD analysis for implantable cardiac pacemakers EMI due to mobile radios in train carriage of complicate situation were carried out by Higaki et al [Hikage, 2007c].
Hirose et al. invetigated quantitatively the EMI caused by an induction oven in implantable unipolar cardiac pacemakers and measured the distribution profile of the magnetic field strength both with and without a pan on the induction oven [Hirose, 2005]. Then, they performed the inhibition test and asynchrorous test using four kinds of pacemakers housed in the standardized Irnich human body model and the maximum distance from the induction oven up to which the EMI occurred. The maximum EMI distance from the oven was 34 cm for one of the pacemakers. The safe distance from an induction oven of a patient with an implanted cardiac pacemaker is considered to be 50 cm or more.
Although the Computed Tomography (CT) is widely used in clinical practice, there has not been a detailed report of its effect on the function of pacemakers. Yamaji et al. investigated the effect of CT on a pacemaker in a human body mode with and without shielding by rubber or lead and measured ECGs in 11 patients with pacemakers and electromagnetic field in the CT room during CT scanning [Yamaji, 2006]. Transient malfunctions of pacemakers during CT occurred in 6 of 11 patients. The malfunction was prevented by lead but not by rubber. The alternating electric field was 150 V/m and the alternating magnetic field was 15ÊT on the CT scanning line. These field strengths were lower than the level of influencing pacemaker functions.
I would like to thank Dr Okano and the members of Commission K Japan for their tremendous efforts.
Abiko.Y, T.Hikage, Louis-Ray Harris, M.Hirono, T.Nojima, M.Omiya, M.Komazaki, S.Watanabe and T.Shinozuka , gEMF estimations in a train carriage considering of implantable cardiac pacemaker EMI from cellular radios,h 17th International Zurich Symposium on Electromagnetic Compatibility, Topical-meeting notes, pp.51-54, 2006 at Singapore SUNTEC International Convention Exhibition Centre on 27 February-3 March.
Abiko.Y, L.Harris, T.Hikage, T.Nojima,
A.Simba, S.Watanabe and T.Shinozuka , "Electromagnetic field
estimations considering of implantable cardiac pacemaker EMI from cellular
radios in elevators," Proceedings of Progress in Electromagnetics Research
Symposium (PIERS) 2007, p.100,
Arai.S, H.Miura, F.Sato, H.Matsuki and T.Sato . gExamination of circuit parameters for stable high efficiency TETS for artificial hearts.h IEEE Trans on Magnetics, vol.41 (No.10), pp.4170-4172.
Chuman.A, A.Nuruki, S.Tsujimura and K.Yunokuchi , gStudy of electromagnetic effects of IH cooker on Xenopus laevis.hJ Magn Soc Jpn, vol.31, pp.263-267 (in Japanese).
Eguchi.Y and S.Ueno , gStress fiber contributes to rat Schwann cell orientation under magnetic field.h IEEE Trans on Magnetics, vol.41 (no.10), pp.4146-4148.
Eguchi.Y, S.Ueno, C.Kaito, K.Sekimizu and K.Shiokawa , gCleavage and survival of xenopus embryos exposed to 8 T static magnetic fields in a rotating clinostat.h Bioelectromagnetics, vol.27, pp.307-313.
Endo.M, T. Manabe, T. Hikage and T. Nojima , "Experimental investigations on the biological free radical production in human blood cells due to microwave exposure." Biological Effects of EMFs 4th International Workshop 16 - 20 October.
Fujita.A, I.Hirota, Y.Kawahara and H.Omori , gDevelopment and evaluation of intermediate frequency magnetic field exposure system for studies of in vitro biological effects.h, Bioelectromagnetics, vol.28, pp.538-545
Fukushima.M, T.Kataoka, N.Sugiyama and K.Mohri , gMilligauss magnetic field applied pure water exert firefly luciferin-luciferase luminescence and induce intracellular calcium elevation of CHO cells without ATP.h, IEEE Trans on Magnetics, vol.41 (no.10), pp.4188-4190
Funamizu.H, M.Ogiue-Ikeda, H.Mukai, S.Kawato and S.Ueno , gAcute repetitive transcranial magnetic stimulation reactivates dopaminergic system in lesion rats.h, Neuroscience Letters, vol.383 (no.1-2), pp.77-81
Futatsumori.S, T. Hikage, T. Nojima, B. Koike, H. Fujimoto and T. Toyoshima [2006a], "An experimental assessment on implantable medical devices EMI caused by magnetic flux distributions of low-band RFID reader/writers", Proceedings of the 2006 International Symposium on Antennas and Propagation (ISAP 2006), November.
Futatsumori.S, T. Kono, T. Hikage, T. Nojima and B. Koike [2006b], "In vitro experiments to assess electromagnetic fields exposure limits from RFID reader/writer for pacemaker patients," Biological Effects of EMFs 4th International Workshop 16 - 20 October.
T. Kono, T. Hikage, T. Nojima and B. Koike [2006c], "Experimental test
system to assess the EMI from RFID reader/writer on implantable cardiac
pacemaker," PIERS 2006 -
Futatsumori.S, T.Hikage, T.Nojima, B.Koike, H.Fujimoto and T.Toyoshima [2006d], gIn vitro experiments to assess electromagnetic fields exposure effects from RFID reader/writer for pacemaker patients.h Proceedings of Biological Effects of EMFs, 4th International Workshop, pp.494-500, October.
Futatsumori.S, S. Taguchi, T. Hikage, T. Nojima, B. Koike, H. Fujimoto and T. Toyoshima [2007a], "An Assessment methodology of implantable medical device EMI due to RFID reader/writers based upon the EMF distribution analysis", Proceedings of the Bioelectromagnetics Society the 29th Annual Meeting (BEMS2007), P-115, pp. 460-462, June.
Futatsumori.S, T. Hikage, T. Nojima, B. Koike, H. Fujimoto and T. Toyoshima [2007b], "A novel assessment methodology for the EMI occurrence in implantable medical devices based upon magnetic flux distribution of RFID reader/writers", Proceedings of the 2007 IEEE EMC Symposium (EMC 2007), TU-PM-7-5, July.
Gjini.K, T.Maeno, K.Iramina and S.Ueno , gShort-term episodic memory encoding in the human brain: a MEG and EEG study.h IEEE Magnetics, vol.41, pp.4149-4151
Goto.Y, H.Taniura, K.Yamada, T.Hirai, N.Sanada, N.Nakamichi and Y.Yoneda , gThe magnetism responsive gene Ntan1 in mouse brain.h, Neurochem Int, vol.49, pp.334-341
Haga.A, Y.Kumagai, H.Matsuki, G.Endo, A.Igarashi and K.Kobayashi , gEvaluation of damage in DNA molecules caused by very-low-frequency magnetic fields using bacterial cells.h IEICE Trans Comun vol.E88-B, pp.3249-3256
Hamada.S and T.Kobayashi , gAnalysis of electric field induced by ELF magnetic field utilizing fast-multiple surface-charge simulation method for voxel data.h, IEEJ Trans FM, vol.126, pp.355-362 (in Japanese)
Haneda.T, Y.Fujimura and M.Iino , gMagnetic field exposure stiffens regenerating plant protoplast cell walls.h, Bioelectromagnetics, vol.27, pp.98-104
Hanada.E , gThe electromagnetic environment of hospitals: how it is affected by the strength of electromagnetic fields generated both inside and outside the hospital.h Ann Ist Super Sanita, vol.43, pp.208-217
Harakawa.S, N.Inoue, T.Hori, K.Tochio, T.Kariya, K.Takahashi, F.Doge, H.Suzuki and H.Nagasawa , gEffects of a 50 Hz electric field on plasma lipid peroxide level and antioxidant activity in rats.h Bioelectromagnetics, vol.26, pp.589-594
Simba, T. Hikage, T. Nojima, M. Omiya, S. Watanabe and T. Shinoduka ,
"A precise electromagnetic field estimation in elevator considering of
implantable cardiac pacemaker EMI from cellular radios," PIERS 2006,
Hata.K, H.Yamaguchi, G.Tsurita, S.Watanabe, K.Wake and M.Taki , gShort term exposure to 1439 MHz pulsed TDMA field does not alter melatonin synthesis in rats.h Bioelectromagnetics, vol.26, pp.49-53
Hatada.T, M.Sekino and S.Ueno [2005a], gFEM based brain RF electromagnetic field distribution in magnetic resonance imaging.h J Mag Soc Jpn 29, pp.364-367 (in Japanese)
Hatada.T, M.Sekino and S.Ueno [2005b], gFinite element method-based calculation of the theoretical limit of sensitivity for detecting weak magnetic fields in the human brain using magnetic-resonance imaging.h, Journal of Applied Physics, vol.97(no.10), pp.10E109 Part 2
Hikage.T, T. Nojima, S.Watanabe and T.Shinozuka [2005a], gElectric-field distribution estimation in a train carriage due to cellular radios in order to assess the implantable cardiac pacemaker EMI in semi-echoic environments.h IEICE Trans Commun vol.E88-B, (no.8), pp.3281-3286
Hikage.T, Y.Abiko, M.Hirono, T.Nojima, M.Omiya, S.Watanabe and T.Shinozuka [2005b]. gEstimation of the EMF excitation by cellular radios in actual train carriages. -With and without passenger-.h IEEE EMC 2005 Sympoium Proceedings
Hikage.T, T. Manabe, M. Endo and T. Nojima , "Experimental investigations on the biological free radical production in human fibroblasts due to microwave exposure." Proceedings of the Bioelectromagnetics Society the 28th Annual Meeting, PB-78, pp.304-306, June.
Hikage.T, Harris Louis-Ray, Y.Abiko, T.Nojima, Ally Y. Simba and S.Watanabe [2007a], Takashi Shinozuka, "A numerical estimation for human body mitigation effects on implantable cardiac pacemaker Emi from cellular radios used in elevators." Proceedings of the Bioelectromagnetics Society the 29th Annual Meeting (BEMS2007), P-138, pp. 502-504, June.
Hikage.T, M.Endo and T.Nojima [2007b], "In-Vitro experiments on free radical production within human white blood cells due to 900 MHz mobile radio waves exposure." Proceedings of the Bioelectromagnetics Society the 29th Annual Meeting (BEMS2007), 14-5, pp. 233-235, June.
Abiko, M. Hirono, T. Nojima, S. Watanabe and T. Shinozuka [2007c], "Large
scale FDTD analysis for implantable cardiac pacemaker EMI due to mobile radios
in train carriage of complicated situation." Proceeding of EMC
Hikage.T, M.Endo and T.Nojima [2007d], gA new 900 MHz ridged-waveguide microwave exposure equipment to achieve high power density irradiation for In Vitro experiments." Abstracts of EBEA 2007 8th International congress of the European BioElectromagnetics Association, p.28, April.
Hirai.T, H.Taniura, Y.Goto, K.Tamaki, H.Oikawa, Y.Kambe, M.Ogura, Y.Ohno, T.Takarada and Y.Yoneda [2005a], gCounteraction by repetitive daily exposure to static magnetism against sustained blockade of N-methyl-D-aspartate receptor channels in cultured rat hippocampal neurons.h J Neurosci Res, vol.80, pp.491-500.
Hirai.T and Y.Yoneda [2005b], gTranscriptional regulation of neuronal genes and its effect on neural functions: gene expression in response to static magnetism in cultured rat hippocampal neurons.h J Pharmacol Sci, vol.98, pp.219-224.
Hirai.T, H.Taniura, Y.Goto, M.Ogura, J.C.Sng and Y.Yoneda , gStimulation of ubiquitin-proteasome pathway through the expression of amidohydrolase for N-terminal asparagine (Ntan1) in cultured rat hippocampal neurons exposed to static magnetism.h J Neurochem, vol.96, pp.1519-1530
Hirata.A. [2005a], gTemperature increase in human eyes due to near-field and far-field exposures at 900 MHz, 1.5 GHz, and 1.9 GHz.h, IEEE Transactions on EMC, vol.47, pp.68-76
O.Fujiwara, M.Fujimoto and T.Shiozawa [2005b], gMaximum temperature insreases
in the head and brain for SAR averaging schemes prescribed in safety
guidelines.h IEEE International Sym on EMC,
Hirata.A, S.Watanabe, M.Kojima, O.Fujiwara, K.Wake and M.Taki [2006a], gComputational verification of anesthesia effect on temperature variations in rabbit eyes exposed to 2.45 GHz microwave energy.h Bioelectromagnetics, vol.27, pp.602-612
Hirata.A, O.Fujiwara, T.Shiozawa, [2006b]. gCorrelation between peak spatial-average SAR and temperature increase due to antennas attached to human trunk.h IEEE Trans Biomed Eng, vol.53, pp.1658-1664
Hirata.A [2007a], gImproved heat transfer modeling of the eye for electromagnetic wave exposures.h IEEE Transactions on BME, vol.54, pp.959-961
Hirata.A and O.Fujiwara [2007b], gDosimetry in Japanese male and female models for a low-frequency electric field.h Phys Med Biol, vol.52, pp.N339-N343.
Hirata.A, S.Kodera, J.Wang and O.Fujiwara [2007c], gDominant factors influencing whole-body average SAR due to far-field exposure in whole-body resonance frequency and GHz regions.h Bioelectromagnetics, vol.28, pp.484-487
Hirata.A, T.Asano and O.Fujiwara [2007d], gFDTD analysis of human body-core temperature elevation due to RF far-field energy prescribed in the ICNIRP guidelines.h Phys Med Biol, vol.52, pp.5013-5023.
Hirata.A, S.Watanabe, O.Fujiwara, M.Kojima, K.Sasaki and T.Shiozawa [2007e], gTemperature elevation in the eye of anatomically based human head models for plane-wave exposures.h Phys Med Biol, vol.52, pp.6389-6699
Hirata.A, T.Asano and O.Fujiwara [2007f], gFDTD Computation of temperature elevation in human body for RF far-field exposure.h Conf Proc IEEE Eng Med Biol Soc, vol.1, pp.1164-1167
Hirata.K, T.Hara, Y.Oshima, T.Yoshikawa and S.Fujimoto , gEffects of electrical stimulation and voluntary exercise on muscle oxygenation assessed by NIRS.h Osaka City Med J, vol.52, pp.67-78
Hirayama.A, Y.Saitoh, H.Kishima, T.Shimokawa, S.Oshino, M.Hirata, A.Kato, and T.Yoshimine , gReduction of intractable deafferentation pain by navigation-guided repetitive transcranial magnetic stimulation of the primary motor cortex.h Pain vol.122, pp.22-27
Hiroe.A, K. Saito, M. Takahashi and K. Ito , gHeating performances of a coaxial-slot antenna for thermal treatment of bile duct carcinoma | Experimental estimation of cooling effect due to a thick blood vessel |.h IEICE Transactions on Communications B, vol. J89-B, pp.2271-2274 (in Japanese)
Hiroe.A, K. Saito, M. Takahashi and K. Ito , gDevelopment on phantom for measurement of temperature rises inside biological tissue by electromagnetic waves exposure.h IEICE Transactions on Communications B, vol. J90-B, No.11, pp.1187-1192 (in Japanese)
Hirose.H, N.Sakuma, N.Kaji, T.Suhara, M.Sekijima, T.Nojima and J.Miyakoshi , gPhosphorylation and gene expression of p53 are not affeced in human cells exposed to 2.1425 GHz band CW or W-CDMA modulated radiation allocated to mobile radio base stations.h Bioelectromagnetics, vol.27, pp.494-504
Hirose.H, N.Sakuma, N.Kaji, K.Nakayama, K.Inoue, M.Sekijima, T.Nojima and J.Miyakoshi , gMobile phone base station-emitted radiation does not induce phosphorylation of hsp27.h Bioelectromagnetics, vol.28, pp.99-108
Hirose.M, M.Hida, E.Sato, K.Kokubo, M.Nie and H.Kobayashi , gElectromagnetic interference of implantable unipolar cardiac pacemakers by an induction oven.h PACE, vol.28, pp.540-548
Hodaka.S, Y.Ozu, S.Satomi, Y.Nihei, Y.Kurokawa and T.Sato , gThermotherapy with metallic stent heated by external magnetic excitation.h IEEE Trans on Magnetics, vol.41 (no.10), pp.4167-4169
Horikawa-Miura.M., N.Matsuda, M.Yoshida, Y.Okumura, T.Mori and M.Watanabe , gThe greater lethality of UVB radiation to cultured human cells is associated with the specific activation of a DNA damage-independent signaling pathway.h Radiation Research, vol.167, pp.655-662
Ikehata, M., S. Yoshie, Y. Takashima and T. Koana , gExposure to magnetic fields and mutagenesis,h IEEJ MAG-06-51 (in Japanese).
Ikehata, M., Y. Suzuki, S. Yoshie, M. Taki and T. Koana , gEstimation of biological effects by exposure to complex magnetic fields with static and 50Hz components,h Proceedings of the Bioelectromagnetics Society the 28th Annual Meeting (BEMS2006), PA-81, pp.92-93, June.
Ikehata, M., Y. Suzuki, S. Yoshie, K. Wake, S. Nakasono and M. Taki , gEvaluation of mutagenicity by exposure to intermediate frequency magnetic fields in mouse lymphoma assay,h Book of abstracts of EBEA2007 8th International Congress of European BioElectromagnetics Association, P-90, April.
Ikehata, M., Y. Suzuki, S. Yoshie, K. Wake, S. Nakasono and M. Taki , gEvaluation of mutagenicity by exposure to intermediate frequency magnetic fields in mouse lymphoma assay,h Proceedings of the Bioelectromagnetics Society the 29th Annual Meeting (BEMS2007), 5-5, pp. 91-92, June.
Ikehata, M., S. Yoshie, S. Matsumoto, Y. Suzuki, T. Hayakawa , gMutagenicity and Co-mutagenicity of Strong Static Magnetic Field in Yeast Cells,h Proceedings of EHE2007, p9-1, September.
Ikehata, M., S. Yoshie, Y. Suzuki, M. Taki and T. Hayakawa , gEvaluation of mutagenicity of complex magnetic fields with static and extremely low frequency components,h IEICE Technical Report, EMCJ2007-91, pp. 57-61 (in Japanese).
Ikehata, M., S. Yoshie, Y. Suzuki and T. Hayakawa , gEvaluation of mutagenicity and co-mutagenicity of a static magnetic field in yeast cells,h International Conference on Magneto-Science ICMS2007, IIP-22, pp. 132, November.
Ikehata, M., S. Yoshie, Y. Suzuki, T. Hayakawa , gMutagenicity and co-mutagenicity of strong static magnetic field in yeast cells,h 1st Asian Conference on Environmental Mutagens & 36th Annual Meeting of The Japanese Environmental Mutagen Society, November.
Ikehata, M. , gStatic magnetic fields and health,h J. Natl. Inst. Public Health, 56(4), pp. 343-350 (in Japanese).
Imae.T, H.Shinohara, M.Sekino, S.Ueno, H.Ohsaki, K.Mima and K.Ootomo , gMinimization of discrete errors in diffusion simulation of nuclear magnetization.h J. Magn Soc Jpan, vol.31, pp.279-282 (in Japanese)
Inomata-Terada.S, S.Okabe, N.Arai, R.Hanajima, Y.Terao and T.Furubayashi , gEffects of high frequency electromagnetic field (EMF) emitted by mobile phones on the human motor cortex.h Bioelectromagnetics, vol.28, pp.553-561
Iramina.K and S.Ueno . gHigh spatial resolutional measurement of biomagnetic fields.h IEEE Transactions on Magnetics, vol.43 (no.6), pp.2477-2479
Ishii N., T. Akagawa, K.
Sato, L. Hamada, and
Ishikawa.I and M.Tanimura . gVisualization of magnetic leakage flux from a cell phone.h Journal of the Magnetics Society, vol.30, pp.38-39
Ito.K , gAntenna technology applied to medicine.h IEICE Transactions on Communications, vol. J89-B (no.9), pp.1558-1568 (in Japanese)
Ito.K and K. Saito [2007a], gMicrowave antennas for thermal therapy.h Thermal Medicine, vol.23 (no.1), pp.23-30
Ito.K, M.Takahashi and K.Saito [2007b], gDevelopment of a tissue-equivalent solid phantom for UWB band and its application to the evaluation of the interaction between radio terminals and the human body.h IEICE Japan C, vol.J90-C, pp.208-215 (in Japanese)
Iwai.H, K.Ogawa and N.Hatakenaka , gA development of a realistic human phantom in a PDA position for EM evaluation of handset antennas.h IEICE Japan B, vol.J89-B, pp.784-793 (in Japanese)
Iwasaka.M and S.Ueno , gMagnetic-field parallel motion of living cells.h Journal of Applied Physics, vol.97 (no.10), pp.10Q907 Part 3
Iwasaka.M. and S.Ueno [2006a], gMagnetic field effects on near-infrared optical properties of cytochrome oxidase.h Science and Technology of Advanced Materials, vol.7 (no.4), pp.315-318
Iwasaka.M, T.Kurakane, T.Kimura, F.Kimura and S.Ueno [2006b], gMagnetic cell manipulation utilizing magnetic particles and diamagnetic collagen fibers.h Journal of Applied Physics, vol.99 (no.8), pp.08R906
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