iMRS 2000 - PEMF Publications
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PEMF Publications

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1001

Resolution of sleep paralysis by weak electromagnetic fields in a patient with multiple sclerosis

Sleep paralysis refers to episodes of inability to move during the onset of sleep or more commonly upon awakening. Patients often describe the sensation of struggling to move and may experience simultaneous frightening vivid hallucinations and dreams. Sleep paralysis and other manifestations of dissociated states of wakefulness and sleep, which reflect deficient monoaminergic regulation of neural modulators of REM sleep, have been reported in patients with multiple sclerosis (MS). A 40 year old woman with remitting-progressive multiple sclerosis (MS) experienced episodes of sleep paralysis since the age of 16, four years prior to the onset of her neurological symptoms. Episodes of sleep paralysis, which manifested at a frequency of about once a week, occurred only upon awakening in the morning and were considered by the patient as a most terrifying experience. Periods of mental stress, sleep deprivation, physical fatigue and exacerbation of MS symptoms appeared to enhance the occurrence of sleep paralysis. In July of 1992 the patient began experimental treatment with AC pulsed applications of picotesla intensity electromagnetic fields (EMFs) of 5Hz frequency which were applied extracerebrally 1-2 times per week. During the course of treatment with EMFs the patient made a dramatic recovery of symptoms with improvement in vision, mobility, balance, bladder control, fatigue and short term memory. In addition, her baseline pattern reversal visual evoked potential studies, which showed abnormally prolonged latencies in both eyes, normalized 3 weeks after the initiation of magnetic therapy and remained normal more than 2.5 years later. Since the introduction of magnetic therapy episodes of sleep paralysis gradually diminished and abated completely over the past 3 years. This report suggests that MS may be associated with deficient REM sleep inhibitory neural mechanisms leading to sleep paralysis secondary to the intrusion of REM sleep atonia and dream imagery into the waking state. Pineal melatonin and monoaminergic neurons have been implicated in the induction and maintenance of REM sleep and the pathogenesis of sleep paralysis and it is suggested that resolution of sleep paralysis in this patient by AC pulsed applications of EMFs was related to enhancement of melatonin circadian rhythms and cerebral serotoninergic neurotransmission.

1002

Responses of human MG-63 osteosarcoma cell line and human osteoblast-like cells to pulsed electromagnetic fields

We have studied the effects of low-energy, low-frequency pulsed electromagnetic fields (PEMF) on cell proliferation, in both human osteoblast-like cells obtained from bone specimens and in human MG-63 osteosarcoma cell line. Assessment of osteoblastic phenotype was performed both by immunolabeling with antiosteonectin antibody and by verifying the presence of parathyroid hormone receptors. The cells were placed in multiwell plates and set in a tissue culture incubator between a pair of Helmholtz coils powered by a pulse generator (1.3 ms, 75 Hz) for different periods of time. [3H]Thymidine incorporation was used to evaluate cell proliferation. Since it had previously been observed that the osteoblast proliferative response to PEMF exposure may also be conditioned by the presence of serum in the medium, experiments were carried out at different serum concentrations. [3H]Thymidine incorporation increases in osteoblast-like cells, when they are exposed to PEMF in the presence of 10% fetal calf serum (FCS). The greatest effect is observed after 24 hours of PEMF exposure. No effects on cell proliferation are observed when osteoblast-like cells are exposed to PEMF in the presence of 0.5% FCS or in a serum-free medium. On the other hand, PEMF-exposed MG-63 cells show increased cell proliferation either at 10% FCS, 0.5% FCS and in serum-free medium. Nevertheless, the maximum effect of PEMF exposure on MG-63 cell proliferation depends on the percentage of FCS in the medium. The higher the FCS concentration, the faster the proliferative response to PEMF exposure. Our results show that, although MG-63 cells display some similarity with human bone cells, their responses to PEMF's exposure are quite different from that observed in normal human bone cells.

1003

Resting EEG effects during exposure to a pulsed ELF magnetic field

Continuing evidence suggests that extremely low frequency magnetic fields (ELF MFs) can affect animal and human behavior. We have previously demonstrated that after a 15 min exposure to a pulsed ELF MF, with most power at frequencies between 0 and 500 Hz, human brain electrical activity is affected as measured by electroencephalography (EEG), specifically within the alpha frequency (8-13 Hz). Here, we report that a pulsed ELF MF affects the human EEG during the exposure period. Twenty subjects (10 males; 10 females) received both a magnetic field and a sham session of 15 min in a counterbalanced design. Analysis of variance (ANOVA) revealed that alpha activity was significantly lower over the occipital electrodes (O1, Oz, O2) [F(1,16) = 5.376, P < .01, eta2 = 0.418] after the first 5 min of magnetic field exposure and was found to be related to the order of exposure (MF-sham vs. sham-MF). This decrease in alpha activity was no longer significant in the 1st min post-exposure, compared to sham (P > .05). This study is among the first to assess EEG frequency changes during a weak (+/-200 microTpk), pulsed ELF MF exposure.

1004

Resting EEG is affected by exposure to a pulsed ELF magnetic field

An increasing number of reports have demonstrated a significant effect of extremely low frequency magnetic fields (ELF MFs) on aspects of animal and human behavior. Recent studies suggest that exposure to ELF MFs affects human brain electrical activity as measured by electroencephalography (EEG), specifically within the alpha frequency (8-13 Hz). Here we report that exposure to a pulsed ELF MF with most power at frequencies between 0 and 500 Hz, known to affect aspects of analgesia and standing balance, also affects the human EEG. Twenty subjects (10 males; 10 females) received both a magnetic field (MF) and a sham session in a counterbalanced design for 15 min. Analysis of variance (ANOVA) revealed that alpha activity was significantly higher over the occipital electrodes (O1, Oz, O2) [F(1,16) = 6.858; P =.019, eta2 = 0.30] and marginally higher over the parietal electrodes (P3, Pz, P4) [F(1,16) = 4.251; P =.056, eta2 = 0.21] post MF exposure. This enhancement of alpha activity was transient, as it marginally decreased over occipital [F(1,16) = 4.417; P =.052; eta2 = 0.216] and parietal electrodes [F(1,16) = 4.244; P =.056; eta2 = 0.21] approximately 7 min after MF exposure compared to the sham exposure. Significantly higher occipital alpha activity is consistent with other experiments examining EEG responses to ELF MFs and ELF modulated radiofrequency fields associated with mobile phones. Hence, we suggest that this result may be a nonspecific physiological response to the pulsed MFs.

1005

Restless legs syndrome is common among female patients with fibromyalgia

Background: The prevalence of restless legs syndrome (RLS) among the general population is 2-15%, and with fibromyalgia syndrome (FMS) 2%. Both RLS and FMS are more common among women. The aim of our study was to evaluate the prevalence of RLS in a group of female patients diagnosed with FMS and to compare the occurrence of symptoms of daytime sleepiness and experienced sleep disorders between fibromyalgia patients with or without RLS. Method: Three hundred and thirty-two female patients, 20-60 years old, diagnosed with FMS at Sk├Ânviks Rehab between 2002 and 2006, answered a questionnaire mailed to their home address. The questionnaire consisted of the international RLS study group criteria as well as of questions concerning symptoms of insomnia and daytime sleepiness measured according to the Epworth Sleepiness Scale. Results: Nearly 64% of the women were also suffering from RLS. More patients suffering from both RLS and FMS were affected by problems of initiating and maintaining sleep than those suffering from FMS only. More patients suffering from both RLS and FMS did not feel refreshed on awakening compared with those suffering from FMS without RLS. The patients with concomitant RLS and FMS were more often hypersomnolent than those suffering from FMS only. Conclusion: This study shows that 64% of a group of female patients diagnosed with fibromyalgia also concurrently suffered from RLS. Compared with patients who suffer from FMS only, patients with both FMS and RLS more often experience sleep disturbances and pronounced daytime sleepiness.

1006

Restricting exposure to pulsed and broadband magnetic fields

A general procedure is described for application of the new ICNIRP exposure guidelines to pulsed and broadband magnetic fields below 100 kHz. The procedure involves weighting of the spectral components with a function that takes into account the basic restrictions and reference levels. A simple first-order RC response or its piecewise linear equivalent is proposed for the weighting function. The weighting can be performed either on the Fourier transformed sample of the measured signal or in real time by processing the signal with an analog or digital filter circuit. The cut-off frequency of the filter is 820 Hz. The occupational exposure criteria are exceeded when the weighted peak magnetic flux density exceeds 43 microT or equivalently the weighted peak dB/dt exceeds 0.22 T s(-1). The maximal peak exposures allowed by the proposed approach are compared with the stimulation thresholds computed with a stimulation model. The results strongly suggest that the safety margin to the stimulation is greater for non-sinusoidal than for sinusoidal waveforms, and at low frequencies it is higher than at high frequencies. The increase of the low-frequency safety margin is desirable to avoid magnetophosphenes and possible CNS effects that may occur below the level predicted by the classical nerve models. Measurement techniques and examples of measured magnetic fields are presented. Particularly high exposures were measured inside MRI equipment and anti-theft gates.

1008

Results of pulsed electromagnetic fields (PEMFs) in ununited fractures after external skeletal fixation

Of 147 patients with fractures of the tibia, femur and humerus, in whom an average of 3.3 operations had failed to produce union, all were treated with external skeletal fixation in situ and pulsed electromagnetic fields (PEMFs). Of the 147, 107 patients united for an overall success rate of 73%. Union of the femur occurred in 81% and the tibia in 75%. Only five of 13 humeri united. Failure to achieve union with PEMFs was most closely associated with very wide fracture gaps and insecure skeletal fixation devices.

1009

Results of treatment of 22 navicular stress fractures and a new proposed radiographic classification system

Twenty-two navicular stress fractures sustained during athletic activity were retrospectively reviewed for return to activity time and the appearance of fracture pattern on computerized tomography. There were 10 females and nine males, with the average patient age being 27.2 years. Three patients sustained bilateral injuries at separate times. Average follow-up was 36.5 months. Nine patients underwent open reduction, internal fixation (some with bone grafting); this group's average return to activity (RTA) was 3.1 +/- 1.2 months (range, 1.5-5 months). Thirteen patients treated conservatively had an average return to activity of 4.3 +/- 2.8 months (range, 2-13 months). The difference between the two groups' RTA was significant (p = .02). Eleven patients utilized pulsed electromagnetic fields (PEMF) and had an average RTA of 4.2 +/- 3.4 months, 27.3% of those patients with PEMF also had surgery. Two conservatively treated fractures that took 5 and 8 months to RTA, respectively, re-fractured during the treatment process. Retrospective review showed CT fracture patterns in the frontal plane that were classified as: dorsal cortical break (type I), fracture propagation into the navicular body (type II), and fracture propagation into another cortex (type III). This is a proposed classification system. It includes modifiers "A" (avascular necrosis of a portion of the navicular); "C" (cystic changes of the fracture), and "S" (sclerosis of the margins of the fracture), the latter of which was most common in our series, particularly in continually symptomatic patients. Type I fractures were more likely to receive conservative treatment (p = .02) and type III fractures took significantly longer to heal than types I and II (p values .001 and .01, respectively). Type I and II injuries had an average RTA of 3.0 and 3.6 months, respectively. Type III injuries had an average RTA of 6.8 months. Based on our findings, we recommend surgery for patients with these modifiers, particularly with type II and III injuries. Conservative treatment may be prolonged, and requires at least 6 weeks of nonweightbearing in a below-knee cast/boot to be successful.

1011

Reversal of a body image disorder (macrosomatognosia) in Parkinson's disease by treatment with AC pulsed electromagnetic fields

Macrosomatognosia refers to a disorder of the body image in which the patient perceives a part or parts of his body as disproportionately large. Macrosomatognosia has been associated with lesions in the parietal lobe, particularly the right parietal lobe, which integrates perceptual-sensorimotor functions concerned with the body image. It has been observed most commonly in patients with paroxysmal cerebral disorders such as epilepsy and migraine. The Draw-a-Person-Test has been employed in neuropsychological testing to identify disorders of the body image. Three fully medicated elderly Parkinsonian patients who exhibited, on the Draw-a-Person Test, macrosomatognosia involving the upper limbs are presented. In these patients spontaneous drawing of the figure of a man demonstrated disproportionately large arms. Furthermore, it was observed that the arm affected by tremor or, in the case of bilateral tremor, the arm showing the most severe tremor showed the greatest abnormality. This association implies that dopaminergic mechanisms influence neuronal systems in the nondominant right parietal lobe which construct the body image. After receiving a course of treatments with AC pulsed electromagnetic fields (EMFs) in the picotesla flux density applied transcranially, these patients' drawings showed reversal of the macrosomatognosia. These findings demonstrate that transcranial applications of AC pulsed EMFs affect the neuronal systems involved in the construction of the human body image and additionally reverse disorders of the body image in Parkinsonism which are related to right parietal lobe dysfunction.

1012

Reversal of a visuoconstructional deficit in Parkinson's disease by application of external magnetic fields: a report of five cases

Visuoperceptive and visuomotor deficits are among the most frequently encountered abnormalities in neuropsychological testing of patients with Parkinson's disease, being present in up to 90% of cases. Clinically, the presence of visuoperceptive and visuomotor impairment may not be noted by Parkinsonian patients but may contribute to various functional disabilities including difficulties operating a vehicle, ambulating, and dressing. The present communication concerns five medicated Parkinsonian patients who responded to extracranial treatment with magnetic fields in the picotesia range intensity with improvement in motor, behavioral, and autonomic functions as well as visuoconstructional tasks as demonstrated on the Bicycle Drawing test. Specifically, prior to treatment with magnetic fields these patients failed to draw the spokes in the wheels of a bicycle that extended completely to the periphery of the rim. I considered this observation to reflect a specific visuoconstructional deficit inherent to the Parkinsonian disease process. This visuoconstructional impairment was reversed, however, by external applications of magnetic fields. The report supports prior observations demonstrating that picotesla range intensity magnetic fields may bring about reversal of specific cognitive deficits in Parkinsonian patients.

1013

Reversal of a visuoconstructional disorder by weak electromagnetic fields in a child with Tourette's syndrome

Tourette's syndrome (TS), a chronic familial neuropsychiatric disorder of unknown etiology, is characterized clinically by the occurrence of motor and vocal tics and by the presence of a variety of neurobehavioral and neurocognitive abnormalities including hyperactivity, self-mutilatory behavior, obsessive-compulsive behavior, learning disabilities, and conduct disorder. Cognitive deficits related to right hemispheric dysfunction are common in TS patients accounting for decrements in visuospatial, visuoconstructional and visuomotor skills. An 11 year old boy with a 5 years history of TS exhibited during a routine neuropsychological assessment an unusual visuoconstructional disorder which previously has been observed in dyslexic children. Specifically, when instructed to draw a bicycle from memory, he drew spontaneously a design executed from the perspective of a bird's eye view. After receiving a 20 minute treatment session with picotesla range electromagnetic fields (EMFs) applied extracranially, this visuocontructional disorder was spontaneously reversed and he drew an elaborate and detailed bicycle positioned in profile. A placebo EMF treatment, which was administered prior to magnetic therapy, had no effect on this child's visuoconstructional disorder. During the ensuing week there was a marked reduction in the child's hyperactive behavior with attentuation of motor tics. Spontaneous drawing of a bicycle a week after the administration of magnetic therapy was executed in profile although some elements were presented from a bird's eye view. This case demonstrates the potential impact of treatment with picotesla EMFs in reversing specific cognitive deficits in TS related to right posterior hemispheric dysfunction.

1014

Reversal of alexia in multiple sclerosis by weak electromagnetic fields

The occurrence of cognitive deficits in patients with multiple sclerosis (MS) has been recognized since 1877 when Charcot first observed "enfeeblement of memory" in his patients. Cognitive deficits have been reported in almost 50% of patients with a relapsing-remitting course and in a significantly higher percentage of patients with a chronic progressive course leading to intellectual disability which is often severe enough to preclude employment. MS is considered a form of subcortical dementia and the occurrence of classical cortical disorders such as aphasia, agnosia and apraxia is reported to be rare in the disease. However, in my experience alexia, a reading impairment unrelated to visual acuity or visual field defects, is common in patients with MS. Recently, I reported that treatment with picotesla range electromagnetic fields (EMFs) is an efficacious modality in the management of both the motor and cognitive symptoms of MS. Three patients with MS who developed alexia as a manifestation of the disease are presented. In all patients the alexia was reversed several months after they began treatment with EMFs. Since alexia usually reflects a disconnection syndrome whereby lesions involving the left visual cortex and the splenium of the corpus callosum disconnect language association areas from visual association areas, it is suggested that reversal of the alexia in these patients by EMFs was related to improved interhemispheric transcallosal transmission of visual information. In addition, it is conceivable that changes in the metabolism of monoamines, which are involved in visual information processing and reading comprehension, may have been important in causing reversal of the alexia. This report further supports the unique efficacy of this treatment modality in reversing specific cognitive deficits in MS.

1015

Reversal of an acute parkinsonian syndrome associated with multiple sclerosis by application of weak electromagnetic fields

The occurrence of movement disorders and particularly Parkinsonian symptoms is uncommon in patients with multiple sclerosis (MS) despite the rather frequent presence of demyelinating plaques in the basal ganglia. This disparity between the occurrence of clinical symptoms in MS and the distribution of demyelinating plaques suggests that impairment of neurotransmitter functions rather than demyelination may be critical to the clinical manifestations of the disease. A 48 year old woman with remitting-progressive MS developed a bilateral Parkinsonian syndrome in association with acute emotional stress which resolved after she received two brief successive extracerebral applications of low frequency picotesla flux density electromagnetic fields (EMFs). It is believed that in this patient Parkinsonism may have existed in a subclinical form and that acute stress, which previously has been shown to precipitate symptoms of Parkinson's disease, triggered the onset of Parkinsonism by further reducing dopaminergic and serotonergic neurotransmission in the basal ganglia. The rapid reversal of the Parkinsonian syndrome by EMFs was related to a presumed augmentation of dopaminergic and serotonergic neurotransmission which, on the basis of CSF studies, is reduced in chronic MS patients. The efficacy of EMFs in the treatment of Parkinson's disease had been documented previously but this report demonstrates that this treatment modality is beneficial also for the treatment of Parkinsonism developing in the setting of other neurodegenerative disorders.

1016

Reversal of cognitive impairment in an elderly parkinsonian patient by transcranial application of picotesla electromagnetic fields

A 74 year old retired building inspector with a 15 year history of Parkinson's disease (PD) presented with severe resting tremor in the right hand, generalized bradykinesia, difficulties with the initiation of gait with freezing, mental depression and generalized cognitive impairment despite being fully medicated. Testing of constructional abilities employing various drawing tasks demonstrated drawing impairment compatible with severe left hemispheric dysfunction. After receiving two successive transcranial applications, each of 20 minutes duration, with AC pulsed electromagnetic fields (EMFs) of 7.5 picotesla flux density and frequencies of 5Hz and 7Hz respectively, his tremor remitted and there was dramatic improvement in his drawing performance. Additional striking improvements in his drawing performance occurred over the following two days after he continued to receive daily treatments with EMFs. The patient's drawings were subjected to a Reliability Test in which 10 raters reported 100% correct assessment of pre- and post drawings with all possible comparisons (mean 2 = 5.0; p < .05). This case demonstrates in PD rapid reversal of drawing impairment related to left hemispheric dysfunction by brief transcranial applications of AC pulsed picotesla flux density EMFs and suggests that cognitive deficits associated with Parkinsonism, which usually are progressive and unaffected by dopamine replacement therapy, may be partly reversed by administration of these EMFs. Treatment with picotesla EMFs reflects a "cutting edge" approach to the management of cognitive impairment in Parkinsonism.

1017

Reversal of delayed union of anterior cervical fusion treated with pulsed electromagnetic field stimulation: case report

We present a case report of anterior cervical fusion non-union that was successfully treated with pulsed electromagnetic field (PEMF) stimulation. In this case, a C6-C7 nonunion was identified clinically and radiographically 1 year after surgery. Imaging revealed nonunion with partial resorption of the bone graft compared with imaging studies performed 8 months earlier. The patient wore a PEMF stimulation device for 3 h/d for 10 months. After 3 months of treatment, the patient's symptoms were resolved. X-rays obtained after 15 weeks of stimulation showed improvement in bone fusion, and x-rays obtained at 31 weeks after stimulation showed even bone density around the C7 screws. The patient remained symptom-free 13 months after the termination of PEMF stimulation at last assessment. PEMF stimulation demonstrated its clinical potential in healing established nonunion of anterior cervical spine fusion. Its use is noninvasive and can be considered an alternative to surgical intervention in selected patients.

1018

Reversal of micrographia in Parkinson's disease by application of picoTesla range magnetic fields

Micrographia, a common and often early sign of Parkinson's disease (PD), is a sensitive clinical marker of the severity of bradykinesia and rigidity in the disease. As micrographia may be reversed by treatment with dopaminergic drugs and may emerge during therapy with neuroleptic agents, it is thought to reflect striatal dopaminergic deficiency. It has been reported recently that external application of picoTesla range magnetic fields (MF) produced a dramatic improvement in the motor symptoms of PD suggesting that these weak MF enhance striatal dopaminergic neurotransmission. In the present communication, we present a 61 year old patient with PD in whom picoTesla range MF attenuated the severity of bradykinesia and rigidity, improved postural stability, and rapidly reversed the micrographia within 30 minutes after termination of treatment. In contrast, sham (placebo) MF did not influence the severity of the motor symptoms of the disease or the associated micrographia. This report demonstrates the antiParkinsonian effect of picoTesla range MF and highlights the unique efficacy of these weak MF in the therapy of Parkinsonism.

1019

Reversal of the bicycle drawing direction in Parkinson's disease by AC pulsed electromagnetic fields

The Draw-a-Bicycle Test is employed in neuropsychological testing of cognitive skills since the bicycle design is widely known and also because of its complex structure. The Draw-a-Bicycle Test has been administered routinely to patients with Parkinson's disease (PD) and other neurodegenerative disorders to evaluate the effect of transcranial applications of AC pulsed electromagnetic fields (EMFs) in the picotesla flux density on visuoconstructional skills. A seminal observation is reported in 5 medicated PD patients who demonstrated reversal of spontaneous drawing direction of the bicycle after they received a series of transcranial treatments with AC pulsed EMFs. In 3 patients reversal of the bicycle drawing direction was observed shortly after the administration of pulsed EMFs while in 2 patients these changes were observed within a time lag ranging from several weeks to months. All patients also demonstrated a dramatic clinical response to the administration of EMFs. These findings are intriguing because changes in drawing direction do not occur spontaneously in normal individuals as a result of relateralization of cognitive functions. This report suggests that administration of AC pulsed EMFs may induce in some PD patients changes in hemispheric dominance during processing of a visuoconstructional task and that these changes may be predictive of a particularly favourable response to AC pulsed EMFs therapy.

1020

Reversal of visual neglect in Parkinson's disease by treatment with picoTesla range magnetic fields

Visual neglect and impairment in perceptual motor or visuospatial tasks are among the most frequently encountered abnormalities in neuropsychological testing of patients with Parkinson's disease, being present in up to 90% of patients. It has been proposed that neglect reflects an attentional-arousal deficit induced by lesions that interrupt a cortical-limbic-reticular loop. Recently, we have reported that application of extracranial magnetic fields (MF) in the picoTesla range was efficacious in reducing the severity of the motor disability of Parkinsonism as well as improving some of the cognitive abnormalities associated with the disease such as visuoperceptive deficits. We now present a 61 year old fully medicated Parkinsonian patient in whom rapid reversal of left visual neglect as well as improvement in visuoconstructional (drawing) performance was noted immediately after a single external application of MF. We propose that this effect was related to enhancement of directed attention through a mechanism involving an interaction between the pineal gland, which is considered a "magnetosensor," and the reticular formation which mediates arousal and attention. This report demonstrates the efficacy of extremely weak MF in reversing some of the cognitive abnormalities in Parkinsonism, notably neglect and visuoperceptive deficits, which contribute significantly to impairment of the patient's daily living activities.

1021

Reversal of visuospatial deficit on the Clock Drawing Test in Parkinson's disease by treatment with weak electromagnetic fields

Visuospatial deficits are among the most frequently encountered abnormalities in neuropsychological testing of patients with Parkinson's disease, being present in up to 90% of cases. Clinically, impairment of visuospatial functions may not be noted by Parkinsonian patients but may contribute to various functional disabilities including frequent falls, difficulties operating a vehicle, ambulating, and dressing. I have reported recently that treatment with external electromagnetic fields (EMFs) in the picotesla (pT) range intensity is an effective nonpharmacological modality in the management of the motor and various cognitive deficits of Parkinsonism including visuoperceptive and visuospatial functions. The present communication concerns four fully medicated Parkinsonian patients who, in response to treatment with EMFs, exhibited reversal of visuospatial impairments as demonstrated on the Clock Drawing Test. Specifically, prior to treatment with EMFs these patients demonstrated a visuospatial deficit which was evident by the placement of the numbers on the clock distant from the periphery. Following a series of treatments with EMFs this visuospatial deficit was corrected. The report supports prior observations demonstrating that externally applied pT range intensity EMFs may bring about reversal of visuospatial deficits in Parkinsonian patients which usually are not improved by treatment with dopaminergic or anticholinergic drugs.

1022

Reversal of visuospatial hemi-inattention in patients with chronic progressive multiple sclerosis by treatment with weak electromagnetic fields

The occurrence of cognitive impairment including visuoperceptive and visuospatial deficits have long been recognized to occur in patients with multiple sclerosis (MS) particularly among patients with a chronic progressive course. In MS visuospatial and visuoperceptive deficits have been attributed to the presence of diffuse demyelinating plaques which "disconnect" the brainstem reticular formation and other subcortical structures involved in attention and arousal from cortical areas thus causing a state of hypoarousal. It has been reported recently that brief external applications of alternating pulsed electromagnetic fields (EMFs) in the picotesla (pT) range intensity improved visuoperceptive and visuospatial functions in MS patients. The present communication concerns three female patients with chronic progressive course of MS (mean age: 52.3 +/- 2.0 yrs; mean duration of illness: 17.6 +/- 10.2 yrs) who, on tests of free drawings, demonstrated visuospatial hemi-inattention as a feature of more global cognitive deterioration. In all patients brief applications of EMFs rapidly reversed this cognitive deficit. These findings support prior observations demonstrating that pT EMFs may bring about reversal of certain cognitive deficits in MS patients which, to my knowledge, remain unaffected by any other treatment modality.

1023

Reversible osteolysis

This is a case report of a 44-year-old patient in whom osteolytic changes that developed around the distal end of the femoral prosthesis appeared to reverse with the use of antiinflammatory medication and pulsed electromagnetic field stimulation. Most reported cases of osteolysis have been described as showing progressive change at a variable rate. There has not been any previously documented case in which there has been reversal of osteolytic change.

1024

RF dosimetry: a comparison between power absorption of female and male numerical models from 0.1 to 4 ghz

Realistic numerical models of human subjects and their surrounding environment represent the basic points of radiofrequency (RF) electromagnetic dosimetry. This also involves differentiating the human models in men and women, possibly with different body shapes and postures. In this context, the aims of this paper are, firstly, to propose a female dielectric anatomical model (fDAM) and, secondly, to compare the power absorption distributions of a male and a female model from 0.1 to 4 GHz. For realizing the fDAM, a magnetic resonance imaging tomographer to acquire images and a recent technique which avoids the discrete segmentation of body tissues into different types have been used. Simulations have been performed with the FDTD method by using a novel filtering-based subgridding algorithm. The latter is applied here for the first time to dosimetry, allowing an abrupt mesh refinement by a factor of up to 7. The results show that the whole-body-averaged specific absorption rate (WBA-SAR) of the female model is higher than that of the male counterpart, mainly because of a thicker subcutaneous fat layer. In contrast, the maximum averaged SAR over 1 g (1gA-SAR) and 10 g (10gA-SAR) does not depend on gender, because it occurs in regions where no subcutaneous fat layer is present.

1025

RF electric field mapping in MR coils with a quartz crystal

The electric field strength and distribution in MRI/MRS probes was assessed with a quartz crystal whose resonance frequency coincided with the probe frequency. A quartz crystal was used as the sensor because: (i) it was capable of producing a resonance signal when it was excited with a pulsed RF electric field; and (ii) the resonance signal was proportional to the square of the electric field strength (or RF excitation power). The sensor was placed in the vicinity of the MR coil under evaluation and was excited with a short RF pulse applied to the coil and, immediately after the pulse, the resonance signal induced was picked up by the same coil acting as a receiver coil. Intensities of the signals were used to assess the distribution of RF electric fields in the coil. This device is useful for probe design, particularly in the minimization of dielectric losses, which have been attributed to the presence of electric fields in MR coils.

1026

Rhabdomyolysis due to pulsed electric fields

High-voltage electrical trauma frequently results in extensive and scattered destruction of skeletal muscle along the current path. The damage is commonly believed to be mediated by heating. Recent experimental and theoretical evidence suggests, however, that the rhabdomyolysis and secondary myoglobin release that occur also can result from electroporation, a purely nonthermal mechanism. Based on the results of a computer simulation of a typical high-voltage electric shock, we have postulated that electroporation contributes substantially to skeletal muscle damage and could be the primary mechanism of damage in some cases of electrical injury. In this study, we determined the threshold field strength and exposure duration required to produce rhabdomyolysis by the electroporation mechanism. The change in the electrical impedance of intact skeletal muscle tissue following the application of short-duration, high-intensity electric field pulses is used as an indicator of membrane damage. Our experiments show that a decrease in impedance magnitude occurs following electric field pulses that exceed threshold values of 60 V/cm magnitude and 1-ms duration. The field strength, pulse duration, and number of pulses are factors that determine the extent of damage. The effect does not depend on excitation-contraction coupling. Electron micrographs confirm structural defects created in the membranes by the applied electric field pulses, and these represent the first clear demonstration of rhabdomyolysis in intact muscle due to electroporation. These results provide compelling evidence in support of our postulate.

1027

Role of pulsed electromagnetic fields in recalcitrant non-unions

Twenty-nine patients of recalcitrant nonunion of long bones were treated by pulsed electromagnetic fields in an attempt to bring about osteogenesis. The pulse used was rectangular, equal mark space wave in the astable, continuous mode operating at a frequency of 40 Hertz. The success rate was 82.5%. The result was not dependent on the age, sex, time of nonunion or the presence of infection. However, the results were uniformly poor when infection and fracture instability were coexistent in the same patient.

1028

Safety considerations in MR imaging

The authors identify eight areas of potential safety concern during clinical magnetic resonance (MR) imaging. These include (a) biologic effects of the static magnetic field; (b) ferromagnetic attractive "projectile" effects of the static magnetic field; (c) potential effects of the relatively slowly time-varying magnetic field gradients; (d) effects of the rapidly varying radio-frequency (RF) magnetic fields, including RF power deposition concerns; (e) auditory considerations from noise caused by the rapidly pulsed magnetic field gradients; (f) safety considerations concerning superconductive systems, including quenches, use of cryogens, and cryogen storage and handling; (g) psychological effects, such as claustrophobia and anxiety induced because of the examination; and (h) possible effects of the intravenous use of the MR contrast agent gadopentetate dimeglumine. The concerns in each of these categories are elaborated upon, and the available data are presented to clarify their status.

1029

Safety of electromagnetic articulography in patients with pacemakers and implantable cardioverter-defibrillators

PURPOSE: Electromagnetic articulography (EMA) uses a helmet to create alternating magnetic fields for tracking speech articulator movement. An important safety consideration is whether EMA magnetic fields interfere with the operation of speakers' pacemakers or implantable cardioverter-defibrillators (ICDs). In this investigation, individuals with pacemaker/ICD devices were exposed to EMA fields under controlled conditions while potential interference was examined. METHOD: Twelve adults with pacemaker/ICD devices from 3 major manufacturers were assessed for device function before, during, and after exposure to magnetic fields from a Carstens AG100 EMA system. Potential interference was probed, with EMA transmitters positioned at varying distances from the implantable devices and with the EMA system set at different operating strengths. RESULTS: No adverse affects in device operation were observed under any conditions. The only potential complication was temporary telemetry-link interference during device testing in some cases. CONCLUSION: The results suggest that EMA technology may be safely used with patients who have pacemakers and ICDs. However, the present findings do not rule out potential interference with other pacemaker/ICD manufacturers or with different articulography systems. Precautions are suggested for testing individuals with pacemaker/ICDs under EMA conditions.

1030

Safety of the magnetic field generated by a neuronal magnetic stimulator: evaluation of possible mutagenic effects

OBJECTIVE: The possible mutagenicity of a magnetic stimulus was checked using the Ames test with Salmonella typhimurium TA98 and TA100 as tester strains. METHODS: Samples of these bacteria were exposed to a pulsed magnetic field, on the order of 1 T. The magnetic pulses were generated by a neuronal magnetic stimulator with a flat coil. The magnetic stimulus was a continuous sequence of slightly damped half sinusoids at a rate of 5 pulses/s. Exposure times were 2-5 and 15 min. Exposure position was such as to maximise the magnetic field and minimise the induced electric field. Room temperature was maintained at 28.5 +/- 0.5 degrees C and the temperature was measured inside the samples. RESULTS: None of the exposure conditions showed any increase in mutation in either of the two bacterial strains. CONCLUSIONS: These results are discussed in comparison with effects found in the literature. The magnetic stimulation used under the conditions of this study does not appear to have mutagenic effects. This does not apply to cases where both strong electric and magnetic fields are present.

1031

Select modalities

Physical rehabilitation modalities such as therapeutic ultrasound (TU), transcutaneous electrical neuromuscular stimulation (TENS), neuromuscular electrical stimulation (NMES), cold or low-level laser therapy (LLLT), and pulsed magnetic field therapy (PMF) can all, when used properly, assist in treating orthopedic injuries, neurological conditions, and chronic conditions brought about by normal aging in our small animal companions. TU uses sound waves to produce both thermal and nonthermal effects that aid in tissue healing, repair, and function. TENS uses different frequencies of electrical current to decrease pain and inflammation. NMES also uses an electrical current to stimulate muscle contraction to assist in normal neuromuscular function in postorthopedic and neurological injuries. LLLT uses light energy to reduce pain, decrease inflammation, and stimulate healing at a cellular level. PMF uses magnetic field to stimulate normal cellular ion exchange and oxygen utilization and promote generalized healing of tissues. These modalities are discussed in detail covering mechanism of action, parameters, settings, and indications/contraindications of use in our small animals. Although these modalities are important in the physical rehabilitation of small animals, they need to be incorporated with a proper diagnosis, manual therapy, and home exercise program into a specific and individualized patient treatment protocol.

1032

Selective resolution of plaques and treatment of atherosclerosis by I/O physical alteration of the cellular and intracellular properties

this limit area report from Illinois, investigators found that by allowing atherosclerotic lesions to take up magnetically excitable sub micron particles and then applying an external alternating electomagnetic field, the atherosclerotic lesions were selectively resolved without damaging normal blood vessels.

1033

Semiconductor-controlled contour-clamped homogeneous electric field apparatus

The design and construction of a transistor-driven hexagonal contour-clamped homogeneous electric field (CHEF) apparatus is discussed in detail. The addition of computer control of pulsed-field timings and experiment duration gives rise to an efficient electrophoresis tool designed to achieve separation of DNA molecules in different size groupings. In particular, pulse time regimes which lead to the monotonic separation of DNA molecules ranging from 90 kbp to over a megabase pair are demonstrated. Theoretical treatment of electric field clamping with transistor-driven multiple electrodes is supported by measurements and by the actual performance of electrophoretic separation of yeast chromosomes. The large sample capacity of gels run in this apparatus coupled with the modest power requirements necessary to provide a homogeneous electric field offer significant advantages over earlier CHEF designs.

1034

Sensitivities of germinating spores and carvacrol-adapted vegetative cells and spores of Bacillus cereus to nisin and pulsed-electric-field treatment

Treatment of Bacillus cereus spores with nisin and/or pulsed-electric-field (PEF) treatment did not lead to direct inactivation of the spores or increased heat sensitivity as a result of sublethal damage. In contrast, germinating spores were found to be sensitive to PEF treatment. Nisin treatment was more efficient than PEF treatment for inactivating germinating spores. PEF resistance was lost after 50 min of germination, and not all germinated spores could be inactivated. Nisin, however, was able to inactivate the germinating spores to the same extent as heat treatment. Resistance to nisin was lost immediately when the germination process started. A decrease in the membrane fluidity of vegetative cells caused by incubation in the presence of carvacrol resulted in a dramatic increase in the sensitivity to nisin. On the other hand, inactivation by PEF treatment or by a combination of nisin and PEF treatments did not change after adaptation to carvacrol. Spores grown in the presence of carvacrol were not susceptible to nisin and/or PEF treatment in any way.

1035

Separation of large DNA fragments by capillary electrophoresis under pulsed-field conditions

Capillary zone electrophoresis (CZE), using an entangled polyacrylamide solution, was applied to large DNA samples under pulsed-field conditions. Highly efficient separations were achieved under biased sinusoidal field and field-inversion pulsing regimes. The separations that were obtained with 8.3-48.5 kb lambda DNA standards and 48.5 kb-1 Mb lambda DNA concatamers (modified with ethidium bromide) clearly demonstrate a dramatic improvement in the separation time (roughly, 10-50 times) over the conventionally used slab-gel techniques. Moreover, the CZE method appears much more sensitive and amenable to component quantification and method automation.

1036

Serotonergic neuronal atrophy with synaptic inactivation, not axonal degeneration, are the main hallmarks of multiple sclerosis

The neurological manifestations of multiple sclerosis (MS) have been considered to result from demyelination of axons with relative preservation of axonal integrity. This concept has been challenged recently by a landmark pathological study, published in the New England Journal of Medicine, which has demonstrated that axonal degeneration is also present. The authors of the study hypothesized that axonal degeneration is the pathological correlate of the irreversible neurological impairment in this disease. However, this hypothesis cannot be reconciled with the clinical results obtained with transcranial applications of AC pulsed electromagnetic fields (EMFs) of picotesla flux density which have shown rapid and sustained improvement of symptoms including normalization of evoked potential responses in patients with chronic progressive or secondary progressive MS without demyelinated areas first undergoing remyelination or transected axons undergoing regeneration. Biochemical studies have shown that MS patients are serotonergically depleted with the extent of cerebral depletion correlating with the degree of motor disability and a chronic progressive course. It is believed that progressive serotonergic neuronal atrophy with synaptic inactivation, not axonal degeneration, are the hallmarks of the disease and that administration of AC pulsed magnetic fields improves symptoms of MS partly through reactivation of serotonergic neurons and amplification of synaptic serotonergic transmission.

1037

Sex differences in conditioned taste aversion and in the effects of exposure to a specific pulsed magnetic field in deer mice Peromyscus maniculatus

Although conditioned taste aversion (CTA) has been investigated and described in laboratory rodents and domestic animals, less is known regarding wild rodents. Here, we describe CTA in males and females of a "wild" species of rodent, the deer mouse (Peromyscus maniculatus). In addition, as CTA has often been induced by exposure to intense electromagnetic, X or gamma, radiation, in a second study, we also investigated the effects of a specifically designed, pulsed extremely low-frequency and low-intensity magnetic field on the flavor preferences of male and female deer mice. The results of these investigations showed that: (i) deer mice quickly developed a marked CTA for a novel flavor after a single pairing with LiCl; (ii) although the intensity of the CTA was the same in males and females, there was a sex difference in the duration of the flavor aversion, with males displaying it for a longer period (4 days) than females (3 days); (iii) both males and females showed a rapid and complete extinction of the aversion, in contrast to what has been reported for laboratory rodents; (iv) there was no recovery of CTA on re-test 10 days after extinction; (v) neither male or female deer mice developed a taste aversion as a consequence of exposure to a weak electromagnetic field; and (vi) there was a sex difference in response to the magnetic field, with exposure to the magnetic field significantly enhancing novel taste preference in male but not in female deer mice. Overall, our results show that there are several sex differences in the behavior of deer mice, both in the characteristics of the CTA and in the response to magnetic field exposure. The sex differences are discussed in terms of a sexually dimorphic sensitivity to experimental manipulation and the induction of stress and/or anxiety.

1038

Shifts in the Plutchik emotion profile indices following three weekly treatments with pulsed vs continuous cerebral magnetic fields

Compared to baseline measures, the emotional profile indices of normal volunteers who received 3 weekly exposures to 20 min. of bilateral burst-firing magnetic fields along the temporal plane displayed increased aggression and decreased trust relative to those exposed to pulsed (1 sec. every 4 sec.) fields or to control conditions. The effect size was equivalent to an eta of 0.70. There were no shifts in Holtzman Inkblot Projection Scores. These results suggest that brief cerebral exposures to weak magnetic fields that simulate the burst-firing of amygdaloid cells may affect specific limbic emotions.

1039

Short cycles of both static and pulsed electromagnetic fields have no effect on the induction of cytokines by peripheral blood mononuclear cells

We evaluated the effect of short cycles of static and pulsed electromagnetic field exposure on the eventual activation of peripheral blood mononuclear cells. The cells were subjected to three 15-min cycles of EMF, each exposure being followed by 105 min without a field, for a total of 6 hr. The results clearly demonstrate that the proliferative responses of both normal cells and cells stimulated with 1 microg/ml phytohemagglutinin were not distinguishable from control cells not exposed to EMF. Moreover, although the production of interleukin-2, interferon gamma and tumor necrosis factor alpha increased during the first 48 hr of incubation, the values remained unchanged with respect to controls. This indicates that brief exposure to an electromagnetic field has no significant effect on peripheral blood mononuclear cells. The comparison between biological activity and the cytokine antigen present in our samples indicated that the recovery of antigen corresponded to an equal recovery of biological activity, suggesting the absence of either qualitative differences in these proteins or the impairment of transcriptional and translational processes.

1040

Short GSM mobile phone exposure does not alter human auditory brainstem response

BACKGROUND: There are about 1.6 billion GSM cellular phones in use throughout the world today. Numerous papers have reported various biological effects in humans exposed to electromagnetic fields emitted by mobile phones. The aim of the present study was to advance our understanding of potential adverse effects of the GSM mobile phones on the human hearing system. METHODS: Auditory Brainstem Response (ABR) was recorded with three non-polarizing Ag-AgCl scalp electrodes in thirty young and healthy volunteers (age 18-26 years) with normal hearing. ABR data were collected before, and immediately after a 10 minute exposure to 900 MHz pulsed electromagnetic field (EMF) emitted by a commercial Nokia 6310 mobile phone. Fifteen subjects were exposed to genuine EMF and fifteen to sham EMF in a double blind and counterbalanced order. Possible effects of irradiation was analyzed by comparing the latency of ABR waves I, III and V before and after genuine/sham EMF exposure. RESULTS: Paired sample t-test was conducted for statistical analysis. Results revealed no significant differences in the latency of ABR waves I, III and V before and after 10 minutes of genuine/sham EMF exposure. CONCLUSION: The present results suggest that, in our experimental conditions, a single 10 minute exposure of 900 MHz EMF emitted by a commercial mobile phone does not produce measurable immediate effects in the latency of auditory brainstem waves I, III and V.

1041

Short term exposure to 1439 MHz pulsed TDMA field does not alter melatonin synthesis in rats

The widespread use of the mobile phone has initiated many studies on the possible adverse effects of a high frequency electromagnetic field (EMF), which is used in mobile phones. A low frequency EMF is reported to suppress melatonin synthesis. The aim of this study was to clarify the effects on melatonin synthesis in rats after short term exposure to a 1439 MHz time division multiple access (TDMA) EMF. The average specific absorption ratio (SAR) of the brain was 7.5 W/kg, and the average SARs of the whole body were 1.9 and 2.0 W/kg for male and female rats, respectively. A total of 208 male and female rats were investigated. After acclimatization to a 12 h light-dark (LD) cycle, serum and pineal melatonin levels together with pineal serotonin level under a dark condition (less than 1 lux) were examined by radioimmunoassay. 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 EMF, which is about four times stronger than that emitted by mobile phones, does not alter melatonin and serotonin synthesis in rats. Further investigations on the effects of long term exposure are warranted.

1042

Short-term effects of pulsed electromagnetic fields after physical exercise are dependent on autonomic tone before exposure

The therapeutic application of pulsed electromagnetic fields (PEMFs) can accelerate healing after bone fractures and also alleviate pain according to several studies. However, no objective criteria have been available to ensure appropriate magnetic field strength or type of electromagnetic field. Moreover, few studies so far have investigated the physical principles responsible for the impact of electromagnetic fields on the human body. Existing studies have shown that PEMFs influence cell activity, the autonomic nervous system and the blood flow. The aim of this study is to examine the instantaneous and short-term effects of a PEMF therapy and to measure the impact of different electromagnetic field strengths on a range of physiological parameters, especially the autonomic nervous systems, determined by heart rate variability (HRV) as well as their influence on subjects' general feeling of well-being. The study comprised experimental, double-blind laboratory tests during which 32 healthy male adults (age: 38.4+/-6.5 years) underwent four physical stress tests at standardised times followed by exposure to pulsed magnetic fields of varying intensity [HPM, High Performance magnetic field; Leotec; pulsed signal; mean intensity increase: zero (placebo), 0.005, 0.03 and 0.09 T/s]. Exposure to electromagnetic fields after standardised physical effort significantly affected the very low frequency power spectral components of HRV (VLF; an indicator for sympathetically controlled blood flow rhythms). Compared to placebo treatment, exposure to 0.005 T/s resulted in accelerated recovery after physical strain. Subjects with lower baseline VLF power recovered more quickly than subjects with higher VLF when exposed to higher magnetic field strengths. The application of electromagnetic fields had no effect on subjects' general feeling of well-being. Once the magnetic field exposure was stopped, the described effects quickly subsided. PEMF exposure has a short-term dosage-dependent impact on healthy subjects. Exposure to PEMF for 20 min resulted in more rapid recovery of heart rate variability, especially in the very low frequency range after physical strain. The study also showed the moderating influence of the subjects' constitutional VLF power on their response to PEMF treatment. These findings have since been replicated in a clinical study and should be taken into consideration when PEMF treatment is chosen.

1043

Short-term efficacy of physical interventions in osteoarthritic knee pain. A systematic review and meta-analysis of randomised placebo-controlled trials

BACKGROUND: Treatment efficacy of physical agents in osteoarthritis of the knee (OAK) pain has been largely unknown, and this systematic review was aimed at assessing their short-term efficacies for pain relief. METHODS: Systematic review with meta-analysis of efficacy within 1-4 weeks and at follow up at 1-12 weeks after the end of treatment. RESULTS: 36 randomised placebo-controlled trials (RCTs) were identified with 2434 patients where 1391 patients received active treatment. 33 trials satisfied three or more out of five methodological criteria (Jadad scale). The patient sample had a mean age of 65.1 years and mean baseline pain of 62.9 mm on a 100 mm visual analogue scale (VAS). Within 4 weeks of the commencement of treatment manual acupuncture, static magnets and ultrasound therapies did not offer statistically significant short-term pain relief over placebo. Pulsed electromagnetic fields offered a small reduction in pain of 6.9 mm [95% CI: 2.2 to 11.6] (n = 487). Transcutaneous electrical nerve stimulation (TENS, including interferential currents), electro-acupuncture (EA) and low level laser therapy (LLLT) offered clinically relevant pain relieving effects of 18.8 mm [95% CI: 9.6 to 28.1] (n = 414), 21.9 mm [95% CI: 17.3 to 26.5] (n = 73) and 17.7 mm [95% CI: 8.1 to 27.3] (n = 343) on VAS respectively versus placebo control. In a subgroup analysis of trials with assumed optimal doses, short-term efficacy increased to 22.2 mm [95% CI: 18.1 to 26.3] for TENS, and 24.2 mm [95% CI: 17.3 to 31.3] for LLLT on VAS. Follow-up data up to 12 weeks were sparse, but positive effects seemed to persist for at least 4 weeks after the course of LLLT, EA and TENS treatment was stopped. CONCLUSION: TENS, EA and LLLT administered with optimal doses in an intensive 2-4 week treatment regimen, seem to offer clinically relevant short-term pain relief for OAK.

1044

Short-term exposure to mobile phone base station signals does not affect cognitive functioning or physiological measures in individuals who report sensitivity to electromagnetic fields and controls

Individuals who report sensitivity to electromagnetic fields often report cognitive impairments that they believe are due to exposure to mobile phone technology. Previous research in this area has revealed mixed results, however, with the majority of research only testing control individuals. Two studies using control and self-reported sensitive participants found inconsistent effects of mobile phone base stations on cognitive functioning. The aim of the present study was to clarify whether short-term (50 min) exposure at 10 mW/m(2) to typical Global System for Mobile Communication (GSM) and Universal Mobile Telecommunications System (UMTS) base station signals affects attention, memory, and physiological endpoints in sensitive and control participants. Data from 44 sensitive and 44 matched-control participants who performed the digit symbol substitution task (DSST), digit span task (DS), and a mental arithmetic task (MA), while being exposed to GSM, UMTS, and sham signals under double-blind conditions were analyzed. Overall, cognitive functioning was not affected by short-term exposure to either GSM or UMTS signals in the current study. Nor did exposure affect the physiological measurements of blood volume pulse (BVP), heart rate (HR), and skin conductance (SC) that were taken while participants performed the cognitive tasks.

1045

Signatures of electromagnetic surface-shape resonances in scattering of pulsed beams from surface defects

We predict theoretically that electromagnetic resonances supported by surface defects can be detected experimentally by study of the scattering of electromagnetic pulses from these defects, and we formulate the optimal conditions for such experiments. Numerical scattering simulations confirm that the proposed scattering probes unambiguously identify resonance signatures. The approach that we suggest proves to be superior to conventional analysis of features in the dependence of the far-field intensity of scattered monochromatic light on its frequency, since these features do not necessarily point at resonant frequencies.

1046

Simulation of reduced band broadening during single-stranded DNA pulsed field electrophoresis in polyacrylamide gels

Using a computer simulation algorithm based on the reptation model, we investigated the effects of pulsed field gel electrophoresis on the separation of single-stranded DNA molecules in denaturing polyacrylamide gels. Pulsed fields that combine two different field intensities were found to affect the orientation of the reptation tube as well as the electrophoretic velocity, the rate of band broadening, the plate height and the molecular length for which the minimum of mobility was found, in agreement with available experimental results. Due to "memory" effects, pulses alternating between the forward and backward directions can reduce the diffusion constant by many orders of magnitude. Pulses of identical polarity but different intensities reduce the diffusion because stretches of less-oriented DNA segments are conserved during the migration. We suggest that, for DNA sequencing, pulsed fields of fixed polarity should be used to reduce band broadening and not to overcome band inversion or suppress molecular orientation. We conclude that, using a low intensity, constant electric field will lead to smaller band widths than any pulsed field regime, in a similar length of experimental time, but with less complications.

1047

Simultaneous measurement of magnetization and magnetostriction in 50 T pulsed high magnetic fields

To simultaneously perform magnetization and magnetostriction measurements in high magnetic fields, a miniaturized device was developed that combines an inductive magnetometer with a capacitive dilatometer and, therefore, it is called "dilamagmeter." This combination of magnetic and magnetoelastic investigations is a new step to a complex understanding of solid state properties. The whole system can be mounted in a 12 mm clear bore of any cryostat usually used in nondestructive pulsed high field magnets. The sensitivity of both methods is about 10(-5) A m(2) for magnetization and 10(-5) relative changes in length for striction measurements. Measurements on a GdSi single crystal, which are corrected by the background signal of the experimental setup, agree well with the results of steady field experiments. All test measurements, which are up until now performed in the temperature range of 4-100 K, confirm the perfect usability and high stability in pulsed fields up to 50 T with a pulse duration of 10 ms.

1048

Sine waves enhance cellular transcription

We previously showed that quasirectangular, asymmetrical, pulsed electromagnetic (EM) fields of low frequency can induce increased transcription in Sciara salivary gland cells. A symmetrical sine wave with the same frequency as known biologically effective asymmetric signals was studied in the present investigations. The results demonstrated that signal shape was not a major factor in causing augmented transcription. The pattern of grain density in transcription autoradiograms, as well as the size classes of RNA responsive to EM fields, was the same irrespective of asymmetry or symmetry of the signal. Following short-term exposure of the cells to either type of EM field, S values of new transcripts were consistent with those expected for processed and unprocessed messenger RNA.

1049

Single point measurements of magnetic field gradient waveform

Pulsed magnetic field gradients are fundamental to spatial encoding and diffusion weighting in magnetic resonance. The ideal pulsed magnetic field gradient should have negligible rise and fall times, however, there are physical limits to how fast the magnetic field gradient may change with time. Finite gradient switching times, and transient, secondary, induced magnetic field gradients (eddy currents) alter the ideal gradient waveform and may introduce a variety of undesirable image artifacts. We have developed a new method to measure the complete magnetic field gradient waveform. The measurement employs a heavily doped test sample with short MR relaxation times (T(1), T(2), and T(2)(*)<100 micros) and a series of closely spaced broadband radiofrequency excitations, combined with single point data acquisition. This technique, a measure of evolving signal phase, directly determines the magnetic field gradient waveform experienced by the test sample. The measurement is sensitive to low level transient magnetic fields produced by eddy currents and other short and long time constant non-ideal gradient waveform behaviors. Data analysis is particularly facile permitting a very ready experimental check of gradient performance.

1050

Slow and rapid responses to CW and pulsed microwave radiation by individual Aplysia pacemakers

Specific absorption rates (SARs) of microwave energy that altered firing rates were determined for individual pacemaker neurons in the abdominal ganglion of Aplysia californica. A stripline apparatus provided both for artifact-free recording of transmembrane potentials and for precise determination of the rate of absorption of microwave energy. Exposure for two to three minutes at an SAR of only a few mW/g was capable of changing the firing rate of some pacemakers. Two types of responses were observed. The response that was seen in all neurons developed slowly, reaching a steady state in one to three minutes. The other response was seen in a few neurons and occurred within five seconds from the onset of irradiation. Similar responses were obtained for two microwave frequencies, 1.5 and 2.45 GHz. Pulsed radiation induced rapid changes of firing rate more readily than did CW radiation at the same SAR. A convective heating scheme was used to study the effects of temperature changes on the pacemakers' firing rates. Since all of the responses are not readily explained by general heating of the preparation, alternate mechanisms are suggested for the observed effects.

1051

Solid-state NMR spectroscopy under periodic modulation by fast magic-angle sample spinning and pulses: a review

Fast magic-angle spinning (MAS) holds promise for new approaches to pulsed high-resolution NMR in solids where homogeneous interactions dominate. Prerequisite for developing new pulse methods is the understanding of signal encoding by spin interactions under MAS conditions and of interferences between MAS and pulses. This review discusses corresponding strategies and techniques in a coherent way with particular concentration on homonuclear decoupling techniques for line-narrowing in solids.

1052

Spatial distributions of the energy and energy flux density of partially coherent electromagnetic beams in atmospheric turbulence

The formulas of the energy and energy flux density of partially coherent electromagnetic beams in atmospheric turbulence are derived by using Maxwell's equations. Expressions expressed by elements of electric cross spectral density matrixes of the magnetic and the mutual cross spectral density matrix are obtained for the partially coherent electromagnetic beams. Taken the partially coherent Cosh-Gaussian (ChG) electromagnetic beam as a typical example, the spatial distributions of the energy and energy flux density in atmospheric turbulence are numerically calculated. It is found that the turbulence shows a broadening effect on the spatial distributions of the energy and energy flux density. Some interesting results are obtained and explained with regard to their physical nature.

1053

Spatial heterogeneity not homogeneity of the magnetic field during exposures to complex frequency-modulated patterns facilitates analgesia

24 young (4 mo.) and 24 old (8 mo.) male Wistar rats were exposed for 30 min. on two consecutive days to either a sham-field or to a frequency-modulated magnetic field applied through a pair of solenoids (spatially heterogeneous strength) or a Helmholtz coil (spatially homogeneous strength). The maximum field strength was about 2 microTesla. The rats exposed to the spatially heterogeneous magnetic field but not the homogeneous magnetic field exhibited strong analgesia to thermal stimuli applied to the footpads immediately after the treatment and 30 min. later. The effect accommodated 38% of the variance in the latency to respond to the thermal stimuli. These results suggest that the practice by many researchers in bioelectromagnetism to design coils to generate maximum spatial homogeneity of intensities within the exposure volume when applying complex weak magnetic fields may actually diminish any biological effects.

1054

Spectral Stokes singularities of stochastic electromagnetic beams

The spectral Stokes singularities are introduced to describe the polarization singularities of stochastic electromagnetic beams. The motion and annihilation, as well as the changes in the polarization of spectral Stokes singularities, take place in the free-space propagation. The results are illustrated by numerical examples.

1055

Speech impairment in Parkinson's disease is improved by transcranial application of electromagnetic fields

A 52 year old fully medicated physician with juvenile onset Parkinsonism experienced 4 years ago severe "on-off" fluctuations in motor disability and debilitating speech impairment with severe stuttering which occurred predominantly during "on-off" periods. His speech impairment improved 20%-30% when sertraline (75 mg/day), a serotonin reuptake inhibitor, was added to his dopaminergic medications which included levodopa, amantadine, selegiline and pergolide mesylate. A more dramatic and consistent improvement in his speech occurred over the past 4 years during which time the patient received, on a fairly regular basis, weekly transcranial treatments with AC pulsed electromagnetic fields (EMFs) of picotesla flux density. Recurrence of speech impairment was observed on several occasions when regular treatments with EMFs were temporarily discontinued. These findings demonstrate that AC pulsed applications of picotesla flux density EMFs may offer a nonpharmacologic approach to the management of speech disturbances in Parkinsonism. Furthermore, this case implicates cerebral serotonergic deficiency in the pathogenesis of Parkinsonian speech impairment which affects more than 50% of patients. It is believed that pulsed applications of EMFs improved this patient's speech impairment through the facilitation of serotonergic transmission which may have occurred in part through a synergistic interaction with sertraline.

1056

Sphenopalatine Ganglion Analgesia

The sphenopalatine ganglion and its involvement in the pathogenesis of pain has been the subject of debate for the last 90 years. The ganglion is a complex neural center composed of sensory, motor, and autonomic nerves, which makes it difficult to determine its pathophysiology. Current indications for blockade of the sphenopalatine ganglion include sphenopalatine and trigeminal neuralgia, migraine and cluster headaches, and atypical facial pain. Methods of blockade use local anesthetics, steroids, phenol, and conventional radiofrequency and electromagnetic field- pulsed radiofrequency lesioning. The techniques for blockade range from superficial to highly invasive. Efficacy studies, though few and small, show promise in patients who have failed pharmacologic or surgical therapies.

1057

Spin-frustrated (VO)36+-triangle-sandwiching octadecatungstates as a new class of molecular magnets

Spin-frustrated polyoxometalates, K(11)H[(VO)(3)(SbW(9)O(33))(2)].27H(2)O (1) and K(12)[(VO)(3)(BiW(9)O(33))(2)].29H(2)O (2), containing approximately equilateral and isosceles (VO)(3)(6+)-triangles (V(IV)...V(IV) separation of 5.4-5.5 A) sandwiched by two diamagnetic alpha-B nonatungstate ligands ([SbW(9)O(33)](9)(-) and [BiW(9)O(33)](9)(-)) with approximate D(3)(h) symmetry, are found to show magnetization jumps with distinct hysteresis for the S = (1)/(2) <--> S = (3)/(2) level crossing under fast sweeping pulsed magnetic fields (approximately 10(3) T/s) at T < or = 0.5 K. This unusual phenomenon is attributed to the theoretical prediction of half step magnetization, which is expected for an antiferromagnetic spin triangle with antisymmetrical Dzyaloshinky-Moriya interaction. The degeneracy of the S = (1)/(2) states for 1 is removed by slightly lower symmetry effects of triangular structure for 2. The calorimetry of 1 and 2 shows the heat capacity anomaly at 2 < or = T < or = 20 K which is associated with a thermal excitation from the S = (1)/(2) ground states to the S = (3)/(2) state at zero field. Zero-field splitting energies (5-7 K) between S = (1)/(2) and S = (3)/(2) states for 1 and 2, readily estimated by the level-crossing field for the magnetization, allow us to measure the hyperfine-structural 22 lines due to three equivalent I = (7)/(2) (51)V nuclei, the fine-structural triplet line of the S = (3)/(2) excited state, and the g anisotropy on the high-frequency ESR spectra. The spin-frustrated (VO)(3)(6+)-triangle for 1 and 2 is a good model of the magnetization between pure quantum states S = (1)/(2) and (3)/(2) and provides a new class of single-molecule magnets.

1058

Spine fusion for discogenic low back pain: outcomes in patients treated with or without pulsed electromagnetic field stimulation

Sixty-one randomly selected patients who underwent lumbar fusion surgeries for discogenic low back pain between 1987 and 1994 were retrospectively studied. All patients had failed to respond to preoperative conservative treatments. Forty-two patients received adjunctive therapy with pulsed electromagnetic field (PEMF) stimulation, and 19 patients received no electrical stimulation of any kind. Average follow-up time was 15.6 months postoperatively. Fusion succeeded in 97.6% of the PEMF group and in 52.6% of the unstimulated group (P < .001). The observed agreement between clinical and radiographic outcome was 75%. The use of PEMF stimulation enhances bony bridging in lumbar spinal fusions. Successful fusion underlies a good clinical outcome in patients with discogenic low back pain.

1059

Spontaneous and mitomycin-C-induced micronuclei in human lymphocytes exposed to extremely low frequency pulsed magnetic fields

The cytokinesis block micronucleus method, a very sensitive cytogenetic assay, was used to ascertain the possible genotoxic effects of extremely low frequency pulsed magnetic fields in phytohemagglutinin-stimulated human lymphocytes cultures from 16 healthy donors. Four conditions were studied: i) lymphocytes not exposed to the field (control cultures); ii) lymphocytes exposed to the field; iii) lymphocytes treated with mitomycin-C and not exposed to the field; iv) lymphocytes treated with mitomycin-C and exposed to the field. Mitomycin-C-treated cultures were used as control for the micronucleus method, because it is known that mitomycin-C is a potent genotoxic agent, capable of inducing micronuclei. The frequency of micronuclei in field-exposed cultures was similar to the spontaneous frequency observed in control unexposed-cultures. Moreover, the exposure to pulsed magnetic fields did not affect the frequency of micronuclei induced by mitomycin-C, suggesting that, in the experimental conditions used, this kind of field neither affected the integrity of chromosomes nor interfered with the genotoxic activity of mitomycin-C.

1060

SQUID detected NMR and NQR. Superconducting Quantum Interference Device

The dc Superconducting QUantum Interference Device (SQUID) is a sensitive detector of magnetic flux, with a typical flux noise of the order 1 muphi0 Hz(-1/2) at liquid helium temperatures. Here phi0 = h/2e is the flux quantum. In our NMR or NQR spectrometer, a niobium wire coil wrapped around the sample is coupled to a thin film superconducting coil deposited on the SQUID to form a flux transformer. With this untuned input circuit the SQUID measures the flux, rather than the rate of change of flux, and thus retains its high sensitivity down to arbitrarily low frequencies. This feature is exploited in a cw spectrometer that monitors the change in the static magnetization of a sample induced by radio frequency irradiation. Examples of this technique are the detection of NQR in 27Al in sapphire and 11B in boron nitride, and a level crossing technique to enhance the signal of 14N in peptides. Research is now focused on a SQUID-based spectrometer for pulsed NQR and NMR, which has a bandwidth of 0-5 MHz. This spectrometer is used with spin-echo techniques to measure the NQR longitudinal and transverse relaxation times of 14N in NH4ClO4, 63+/-6 ms and 22+/-2 ms, respectively. With the aid of two-frequency pulses to excite the 359 kHz and 714 kHz resonances in ruby simultaneously, it is possible to obtain a two-dimensional NQR spectrum. As a third example, the pulsed spectrometer is used to study NMR spectrum of 129Xe after polariza-tion with optically pumped Rb. The NMR line can be detected at frequencies as low as 200 Hz. At fields below about 2 mT the longitudinal relaxation time saturates at about 2000 s. Two recent experiments in other laboratories have extended these pulsed NMR techniques to higher temperatures and smaller samples. In the first, images were obtained of mineral oil floating on water at room temperature. In the second, a SQUID configured as a thin film gradiometer was used to detect NMR in a 50 microm particle of 195Pt at 6 mT and 4.2 K.

1061

Stark tuning of donor electron spins in silicon

We report Stark shift measurements for 121Sb donor electron spins in silicon using pulsed electron spin resonance. Interdigitated metal gates on a Sb-implanted 28Si epilayer are used to apply the electric fields. Two quadratic Stark effects are resolved: a decrease of the hyperfine coupling between electron and nuclear spins of the donor and a decrease in electron Zeeman g factor. The hyperfine term prevails at magnetic fields of 0.35 T, while the g factor term is expected to dominate at higher magnetic fields. We discuss the results in the context of the Kane model quantum computer.

1062

Static electromagnetic fields generated by corrosion currents inhibit human osteoblast differentiation

STUDY DESIGN: Human osteoblast cultures were exposed to a very low intensity static magnetic fields (SMF) to investigate its effects on osteoblast growth and differentiation. OBJECTIVE: Analysis of the effects of periprosthetic SMF on the growth and differentiation of human osteoblast cell cultures in vitro. SUMMARY OF BACKGROUND DATA: The effects of pulsed electromagnetic fields (PEMF) on cell proliferation, especially in human osteoblast-like cells is well described, whereas few data are available on the effects of SMF on osteoblast cell culture. We previously demonstrated that the proliferation of human osteoblast cultures is reduced when cells are exposed to a continuous low intensity SMF comparable to the one that occurs around metal devices (Ti spinal implant) because of the generation of electric currents between the screw (Ti6Al4V) and the rod (Ti). METHODS: Primary osteoblastic cells were isolated from a human femoral head. Osteoblast cultures were exposed to SMF and alkaline phosphatase activity was evaluated in the osteoblast cell cultures at different time points. Reverse transcriptase-polymerase chain reaction (RT-PCR) was performed to evaluate mRNA expression levels of osteocalcin, Runx2, and collagen I genes. RESULTS: The SMF-treated cells showed a progressive increase in the alkaline phosphatase activity which, however, remained always lower than the one observed in the control group at each observation time (72 hours, 7 and 14 days). RT-PCR demonstrated that Runx2 and collagen I mRNA were downregulated following SMF stimulation, whereas no change in osteocalcin mRNA was observed. CONCLUSION: Continuous low-intensity electromagnetic field comparable to the one that generates around metal devices because of the generation of corrosion currents inhibits osteoblasts differentiation pattern and might contribute at least in part to a decrease in periprosthetic bone formation occurring in vivo.

1063

Static electromagnetic fields induce vasculogenesis and chondro-osteogenesis of mouse embryonic stem cells by reactive oxygen species-mediated upregulation of vascular endothelial growth factor

Electromagnetic fields (EMFs) are used to treat bone diseases. Herein, the effects of static EMFs on chondro-osteogenesis and vasculogenesis of embryonic stem (ES) cells and bone mineralization of mouse fetuses were investigated. Treatment of differentiating ES cells with static EMFs (0.4 to 2 mT) stimulated vasculogenesis and chondro-osteogenesis and increased reactive oxygen species (ROS) which was abolished by the free radical scavengers trolox, 1,10-phenanthroline (phen), and the NAD(P)H oxidase inhibitor diphenylen iodonium (DPI). In contrast EMFs of 10 mT field strength exerted inhibitory effects on vasculogenesis and chondro-osteogenesis despite robust ROS generation. EMFs of 1 mT and 10 mT increased and decreased vascular endothelial growth factor (VEGF) expression, respectively, which was abolished by DPI and radical scavengers. EMFs activated extracellular regulated kinase 1/2 (ERK1/2), p38 and c-jun N-terminal kinase (JNK) which was sensitive to DPI treatment. The increase in VEGF by EMFs was inhibited by the ERK1/2 inhibitor U0126 but not with SB203580 and SP600125 which are p38 and JNK inhibitors, respectively, suggesting VEGF regulation by ERK1/2. Chondro-osteogenesis and vasculogenesis of ES cells was blunted by trolox, DPI and the VEGF receptor-2 (flk-1) antagonist SU5614. In mouse fetuses 1 mT EMFs increased and 10 mT EMFs decreased bone mineralization which was abolished in the presence of trolox. Hence, EMFs induced chondro-osteogenesis and vasculogenesis in ES cells and bone mineralization of mouse fetuses by a ROS-dependent upregulation of VEGF expression.

1064

Statistical review of the henhouse experiments: the effects of a pulsed magnetic field on chick embryos

This paper analyzes data from a study conducted by the United States Office of Naval Research on the effects of pulsed magnetic fields on chick embryos. The experiment involved incubation of eggs under carefully controlled conditions in six different laboratories. The original analysis included inappropriate statistical methodology for analyzing the experimental results. Since the conclusions from this study rest so heavily on the results of statistical analyses, choosing the proper methodology is imperative. The major aim of this paper then is to introduce more appropriate analytic tools and illustrate their use in the present context. Qualitatively our results agree with those of the original analysis; our findings about interactions between effects, however, makes interpretation of these effects more subtle. We apply linear logistic modeling to counts of damaged embryos, using as covariates factors corresponding to exposure, laboratory, incubator, run, and measurements of background radiation. This facilitates estimation of the size of the effects. The effects of laboratory, incubator, and run are explored both as fixed and random effects. We find statistically significant exposure and laboratory effects, in accordance with the original study. However, we also find that the inter-laboratory variation in exposure effect is at least as large as the exposure effect itself. The presence of such effects fundamentally alters the interpretation of the fitted model, as is graphically presented.

1065

Sterilization of Escherichia coli cells by the application of pulsed magnetic field

The inactivation of microorganisms by pulsed magnetic field was studied. It was improved that the application of electromagnetic pulses evidently causes a lethal effect on E. coli cells suspended in phosphate buffer solution Na2HPO4/NaH2PO4 (0.334/0.867 mmol/L). Experimental results indicated that the survivability (N/N0; where N0 and N are the number of cells survived per milliliter before and after electromagnetic pulses application, respectively) of E. coli decreased with magnetic field intensity B and treatment time t. It was also found that the medium temperatures, the frequencies of pulse f, and the initial bacterial cell concentrations have determinate influences in destruction of E. coli cells by the application of magnetic pulses. The application of an magnetic intensity B = 160 mT at pulses frequency f= 62 kHz and treatment time t = 16 h result in a considerable destruction levels of E. coli cells (N/N0 = 10(-4)). Possible mechanisms involved in sterilization of the magnetic field treatment were discussed. In order to shorten the treatment time, many groups of parallel inductive coil were used. The practicability test showed that the treatment time was shortened to 4 h with the application of three groups of parallel coil when the survivability of E. coli cells was less than 0.01%; and the power consumption was about 0.2 kWh/m3.

1066

Stimulation of experimental endochondral ossification by low-energy pulsing electromagnetic fields

Pulsed electromagnetic fields (PEMFs) of certain configuration have been shown to be effective clinically in promoting the healing of fracture nonunions and are believed to enhance calcification of extracellular matrix. In vitro studies have suggested that PEMFs may also have the effect of modifying the extracellular matrix by promoting the synthesis of matrix molecules. This study examines the effect of one PEMF upon the extracellular matrix and calcification of endochondral ossification in vivo. The synthesis of cartilage molecules is enhanced by PEMF, and subsequent endochondral calcification is stimulated. Histomorphometric studies indicate that the maturation of bone trabeculae is also promoted by PEMF stimulation. These results indicate that a specific PEMF can change the composition of cartilage extracellular matrix in vivo and raises the possibility that the effects on other processes of endochondral ossification (e.g., fracture healing and growth plates) may occur through a similar mechanism.

1067

Stimulation of osteoblast growth by an electromagnetic field in a model of bone-like construct

The histogenesis of bone tissue is strongly influenced by physical forces, including magnetic fields. Recent advances in tissue engineering has permitted the generation of three dimensional bone-like constructs. We have investigated the effects of electromagnetic stimulation on human osteoblast cells grown in a hydrophobic polyurethane scaffold. Bone-like constructs were stimulated by pulsed electromagnetic fields in a bioreactor. Proliferation, bone protein expression and calcified matrix production by osteoblasts were measured using histochemical methods. In stimulated cultures, the number of cells was significantly higher compared to static (control) cultures. In both stimulated and control cultures, cells were immunoreactive to osteoblast markers, including type-I collagen, osteocalcin and osteopontin, thus suggesting that the expression of bone-related markers was maintained throughout the in vitro experiments. Morphometric analysis of von Kossa-stained sections revealed that stimulation with electromagnetic field significantly increased matrix calcification. The data lend support to the view that the application of a magnetic field can be used to stimulate cell growth in bone-like constructs in vitro. This finding may be of interest for the production of biomaterials designed for clinical applications.

1068

Stimulation of rat sciatic nerve regeneration with pulsed electromagnetic fields

The effects of pulsed electromagnetic fields (PEMF) on rat sciatic nerve regeneration after a crush lesion were determined. The rats were placed between a pair of Helmholtz coils and exposed to PEMF of frequency 2 Hz and magnetic flux density of 0.3 mT. A 4 h/day treatment for 3-6 days increased the rate of nerve regeneration by 22%. This stimulatory effect was independent of the orientation of the coils. Exposure times of 1 h/day-10 h/day were equally effective in stimulating nerve regeneration. Rats exposed to PEMF for 4 h/day for 7 days before crush, followed by 3 days after crush without PEMF, also showed significantly increased regeneration. This pre-exposure 'conditioning' effect suggests that PEMF influences regeneration indirectly.

1069

Stimulation of regeneration of the rat sciatic nerve by 50 Hz sinusoidal magnetic fields.

The authors noted significant increases in regeneration rates at 250, 500, and 1000 Hz with no effect at 50 or 2000 Hz. The maximal response was obtained at a frequency of 1000 Hz with the regeneration rate increased by 24%.

1070

Studies of exposure of rabbits to electromagnetic pulsed fields

Dutch rabbits were acutely exposed to electromagnetic pulsed (EMP) fields (pulse duration 0.4 mus, field strengths of 1--2 kV/cm and pulse repetition rates in the range of 10 to 38 Hz) for periods of up to two hours. The dependent variables investigated were pentobarbital-induced sleeping time and serum chemistry (including serum triglycerides, creatine phosphokinase (CPK) isoenzymes, and sodium and potassium). Core temperature measured immediately pre-exposure and postexposure revealed no exposure-related alterations. Over the range of field strengths and pulse durations investigated no consistent, statistically significant alterations were found in the end-points investigated.

1071

Studies of the interactions between melatonin and 2 Hz, 0.3 mT PEMF on the proliferation and invasion of human breast cancer cells

Interactions between the hormone melatonin at pharmacological concentrations (10(-3) M) and 2 Hz, 0.3 mT pulsed electromagnetic fields (PEMF) on the proliferation and invasion of human breast cancer cells were studied in vitro. Three types of human breast cancer cells were used in this study: MDA-MB-435, MDA-MB-231, and MCF-7. Results showed that cellular growth of MDA-MB-231 cells, which were reported to be lowly metastatic, and MCF-7 cells, which were reported to be nonmetastatic, were both significantly reduced by melatonin regardless of the presence of the field. Results also showed that MDA-MB-435 and MDA-MB-231 cells were invasive, with MDA-MB-231 cells being more invasive than the MDA-MB-435 cells for both unexposed and experimental-PEMF groups. In addition, invasion studies showed that MCF-7 cells were not invasive and that melatonin did not have any effects on the invasion of these cells, with or without the PEMF. It is also suggested that since metastasis requires growth and invasion into tissue, anti-invasion agents can be used in conjunction with melatonin to prevent formation of secondary metastases. The overall studies suggest that PEMF at 2 Hz, 0.3 mT does not influence cancer metastasis; while having clinical merit in the healing of soft tissue injury, this field has shown no influence on cancer cells as 60 Hz power line fields have.

1072

Studies on antioxidant enzymes in mice exposed to pulsed electromagnetic fields

In this study, 56 female albino mice weighing 30-35 g were used. The animals were divided into a control and an experimental group. The animals in the experimental group were subjected to a pulsed electromagnetic field (PEMF) with a field magnitude of 50 Hz and 2 mT for 8h each day between 0900 and 1700 for 90 days. In both control and experimental groups, blood was sampled at 45, 60, and 90 days in heparinized tubes and erythrocyte malondialdehyde levels, and superoxide dismutase, glutathione peroxidase, catalase, and glucose-6-phosphate dehydrogenase activities were determined. The results revealed that the PEMF applied chronically within the given period and field magnitude does not cause oxidative damage.

1073

Study of Pacemaker and Implantable Cardioverter Defibrillator Triggering by Electronic Article Surveillance Devices (SPICED TEAS)

The magnetic fields emitted by electronic article surveillance (EAS) systems (shoplifting gates) are a source of interference for implanted medical devices. In the Study of Pacemaker and Implantable Cardioverter Defibrillator Triggering by Electronic Article Surveillance Devices (SPICED TEAS), 25 adult volunteers with ICDs and 50 with pacemakers were exposed to the fields of six different EAS systems. These EAS systems used three modes of operation: magnetic audio frequency, swept radiofrequency, and acoustomagnetic technology. No ICD exhibited interference mimicking sensing of tachyarrhythmias with any EAS system. Pacemakers interacted variably, depending on the type of EAS system. Swept radiofrequency systems produced no interaction with any implanted medical device. One magnetic audio frequency system interacted with 2 of 50 pacemakers. The acoustomagnetic system interacted with 48 of 50 pacemakers. Interactions included asynchronous pacing, atrial oversensing (producing "EAS induced tachycardia" in the ventricle), ventricular oversensing (with pacemaker inhibition), and paced beats resulting from the direct induction of current in the pacemaker ("EAS induced pacing"). These interactions produced symptoms in some patients (palpitations, presyncope) only while patients were in the EAS field. No pacemaker was reprogrammed. We conclude that high energy, pulsed low frequency EAS systems such as acoustomagnetic systems interfere with most pacemakers. Pacemaker patients should be advised to minimize exposure to the fields of such systems to prevent the possibility of serious clinical events.

1074

Study of the effects on DNA of electromagnetic fields using clamped homogeneous electric field gel electrophoresis

A clamped homogeneous electric field (CHEF) electrophoresis allowing the separation of DNA molecules in the range of 200 to 3000 kb in size was used to study the biological effects of electric and magnetic fields (EMFs). The results obtained did not show any detectable genomic damage on Saccharomyces cerevisiae.

1075

Studying gene expression profile of rat neuron exposed to 1800MHz radiofrequency electromagnetic fields with cDNA microassay

A widespread use of mobile phone (MP) evokes a growing concern for their possible adverse effects on human, especially the brain. Gene expression is a unique way of characterizing how cells and organism adapt to changes in the external environment, so the aim of this investigation was to determine whether 1800 MHz radiofrequency electromagnetic fields (RF EMF) can influence the gene expression of neuron. Affymetrix Rat Neurobiology U34 array was applied to investigate the changes of gene expression in rat neuron after exposed to the pulsed RF EMF at a frequency of 1800 MHz modulated by 217 Hz which is commonly used in MP. Among 1200 candidate genes, 24 up-regulated genes and 10 down-regulated genes were identified after 24-h intermittent exposure at an average special absorption rate (SAR) of 2 W/kg, which are associated with multiple cellular functions (cytoskeleton, signal transduction pathway, metabolism, etc.) after functional classification. The results were further confirmed by quantitative real-time polymerase chain reaction (RT PCR). The present results indicated that the gene expression of rat neuron could be altered by exposure to RF EMF under our experimental conditions.

1076

Sub-microsecond, intense pulsed electric field applications to cells show specificity of effects

Application of sub-microsecond duration (60-300 ns), intense (15-60 kV/cm) pulsed electric fields (sm/i-PEF) to six types of human cells was examined for its effects on individual cell surface membrane permeability and membrane potential. With short (60 ns) pulses, increasing percentages of Jurkat cells showed propidium iodide (PI) uptake at progressively shorter post-pulse times as the pulse train increased from 1 to 10 sequential pulses, while human blood polymorphonuclear leukocytes (PMN) were unresponsive to these short pulses regardless of train size. With 300 ns pulses, a similar pattern (increasing percentages of cells taking up PI, and progressively shorter times of onset after pulse applications as pulse train size increased) was seen with both Jurkat cells and PMN, but the patterns for both effects were different. Jurkat cell size did not appear to influence the responsiveness of this cell type. Comparisons of sm/i-PEF-induced PI uptake by human monocyte-derived macrophages vs. aged human mononuclear cells, human trunk skin (HTS) cells vs. fresh human mononuclear cells and human macrophages vs. HTS cells showed similar overall effects, but with differences between the patterns for each cell type compared (except the macrophages vs. HTS cells comparison). Application of sm/i-PEFs also caused different patterns of membrane potential loss in Jurkat cells vs. PMN. Jurkat cells developed significant decreases in t heir membrane potential only following the highest intensity pulse applications examined, i.e., 300 ns, 60 kV/cm x5, while PMN showed this effect over the entire range of pulse intensities (300 ns, 15-60 kV/cm, x5) applied. These data indicate that sm/i-PEF applications can have "specificity" (i.e., achieve different levels of effect in different cell types), that cell size does not appear to be the major factor determining sm/i-PEF effects in either Jurkat cells or PMN, that heterogeneous sm/i-PEF effects on cells tend to become homogeneous with increasing pulse train size, and that specificity of sm/i-PEF applications effects can occur at either end of the sm/i-PEF intensity spectrum examined.

1077

Subwavelength electromagnetic near-field imaging of point dipole with metamaterial nanoslab

We investigate near-field imaging of a point dipole by a lossy, nanoscale metamaterial slab. Making use of the electromagnetic angular-spectrum representation, we derive the Green tensor for the field transmission through the metamaterial slab, duly considering multiple reflections, polarizations, and wave-vector signs. With this general formalism, we calculate the point-spread function of the imaging system, which enables us to assess, for instance, resolution and image brightness. Our results demonstrate that with the metamaterial-slab lens one achieves resolution beyond the conventional diffraction limit of half the wavelength. In general, the resolution and image brightness are degraded when the slab thickness and absorption increase, but we show that in some cases the resolution is rather insensitive to the magnitude of the losses in the metamaterial.

1078

Successful treatment of an acute exacerbation of multiple sclerosis by external magnetic fields

A 55 year old woman with multiple sclerosis presented with a 5 week history of an exacerbation of symptoms. Prominent among these symptoms was trigeminal neuralgia, migraine headaches, blurring of vision, and ataxia of gait. While treatment with carbamazepine (TegretolR) (800 mg/d) and oral prednisolone (15 mg/d) over a 4 week period produced no improvement in symptoms, externally applied magnetic fields (MF) (7.5 picoTesla; 5 Hz) placed over the scalp for a 7 minute period on three different days resulted in a complete resolution of symptoms within two weeks of initiation of treatment. Partial relief of the neuralgic pain and headaches was obtained immediately after completion of the first treatment indicating that resolution of symptoms was related to the effects of MF and not to a spontaneous remission. This is the first report demonstrating the clinical efficacy of pico Tesla range MF in rapidly resolving an acute relapse of MS.

1079

Successful treatment of multiple sclerosis with magnetic fields

The present communication concerns a 50 year-old woman with a 15 year history of chronic-progressive multiple sclerosis (MS) in whom extracranial application of picoTesla magnetic fields (MF) produced a dramatic and sustained improvement in disability. In contrast, administration of melatonin (3 mg, P.O.) produced in this patient a rapid exacerbation of disability which was reversed subsequently by treatment with MF. It is hypothesized that the therapeutic effects of picoTesla MF involve the mediation of the pineal gland which is known to act as a magnetosensor. The report demonstrates, for the first time, the remarkable efficacy of weak MF in the symptomatic treatment of chronic-progressive MS and underscores the pivotal role of the pineal gland in the pathophysiology of MS. If confirmed by a larger cohort of patients, extracranial application of picoTesla MF may prove as an extremely efficacious, nonpharmacological modality for the treatment of MS.

1080

Successful treatment of respiratory dyskinesia with picoTesla range magnetic fields

Respiratory dyskinesia, a syndrome characterized by an irregular respiratory rate, tachypnea, and grunting, is a serious complication of chronic neuroleptic therapy. It frequently occurs in elderly women and is commonly associated with clinical features of Tardive dyskinesia (TD). Respiratory dyskinesia initially was considered to be a rare complication of chronic neuroleptic treatment, but more recent reports indicate that respiratory abnormalities are common in patients treated with antipsychotic medications. The appropriate management of patients with respiratory dyskinesia has not been determined as the underlying pathophysiology is incompletely understood. We present a schizophrenic patient on long term antipsychotic therapy who presented with respiratory dyskinesia associated with symptoms of TD and tardive Tourette's syndrome which emerged coincident with an abrupt withdrawal of neuroleptic therapy. In this patient, external application of picoTesla range magnetic fields (MF) produced rapid attenuation in the severity of respiratory and motor dyskinesias. As the pineal gland is considered a magnetosensor and since exposure of experimental animals and humans to external MF alters melatonin secretion, we then propose that the beneficial effects of MF involve the mediation of the pineal gland which has been implicated previously in the pathophysiology of drug-induced movement disorders including TD.

1081

Suicidal behavior is attenuated in patients with multiple sclerosis by treatment with electromagnetic fields

A marked decrease in the levels of serotonin (5-HT) and its metabolite (5-HIAA) has been demonstrated in postmortem studies of suicide victims with various psychiatric disorders. Depression is the most common mental manifestation of multiple sclerosis (MS) which accounts for the high incidence of suicide in this disease. CSF 5-HIAA concentrations are reduced in MS patients and nocturnal plasma melatonin levels were found to be lower in suicidal than in nonsuicidal patients. These findings suggest that the increased risk of suicide in MS patients may be related to decreased 5-HT functions and blunted circadian melatonin secretion. Previous studies have demonstrated that extracerebral applications of pulsed electromagnetic fields (EMFs) in the picotesla range rapidly improved motor, sensory, affective and cognitive deficits in MS. Augmentation of cerebral 5-HT synthesis and resynchronization of circadian melatonin secretion has been suggested as a key mechanism by which these EMFs improved symptoms of the disease. Therefore, the prediction was made that this treatment modality would result in attenuation of suicidal behavior in MS patients. The present report concerns three women with remitting-progressive MS who exhibited suicidal behavior during the course of their illness. All patients had frequent suicidal thoughts over several years and experienced resolution of suicidal behavior within several weeks after introduction of EMFs treatment with no recurrence of symptoms during a follow-up of months to 3.5 years. These findings demonstrate that in MS pulsed applications of picotesla level EMFs improve mental depression and may reduce the risk of suicide by a mechanism involving the augmentation of 5-HT neurotransmission and resynchronization of circadian melatonin secretion.

1082

Surface-enhanced hyper-Raman spectra and enhancement factors for three SERS chromophores. SEHRS spectra on Ag films at pulse energies below 2 pJ

Hyper-Raman scattering, the nonlinear (two-photon excited) analogue of ordinary Raman scattering, is usually considered to be a weak process that requires high-energy pulsed laser excitation. The sensitivity can be improved greatly by making use of two-photon electronic resonance and/or electromagnetic field enhancement on metal nanoparticle surfaces. Here we demonstrate that hyper-Raman spectra can be obtained from organic dyes on silver colloidal nanoparticle films at laser powers below 1 mW of average power (pulse energies below 2 pJ). These results open the door to exploiting the potential advantages of hyper-Raman scattering for analytical applications.

1083

Surgical and electrical methods in the treatment of congenital and posttraumatic pseudarthrosis of the tibia

This is a report of two adult patients with posttraumatic and seven children with congenital pseudarthroses treated by surgical and electrical methods. Interest was focused primarily on congenital pseudarthroses because of the unquestionable severity of these cases and consequently a very high benefit/risk ratio. Three procedures were used: external (Hoffmann) fixation combined with monophasic or biphasic pulsed current stimulation; internal (transtarsal) fixation combined with pulsed electromagnetic field stimulation; and surgical treatment only, as above, without electrostimulation. Healing was achieved in both treated cases of posttraumatic pseudarthrosis and in nine of 14 instances in cases of congenital pseudarthrosis stimulated electrically, as well as in two instances with no electrostimulation. In seven instances, the bone remained healed for nine months or more, the longest period being almost 5.5 years. Both pulsed current and electromagnetic field stimulation seem to enhance the process of bone healing. However, comparison between the different stimulation methods cannot be made on the basis of the limited material presented here, and the need for more basic studies still exists. Concerning the surgical treatment, it seems that transtarsal fixation is a better choice for congenital pseudarthrosis than fixation with an AO-plate, Rush pin or Hoffmann apparatus.

1084

Survey of electromagnetic field exposure in bedrooms of residences in lower Austria

Previous investigations of exposure to electric, magnetic, or electromagnetic fields (EMF) in households were either about electricity supply EMFs or radio frequency EMFs (RF-EMFs). We report results from spot measurements at the bedside that comprise electrostatic fields, extremely low-frequency electric fields (ELF-EFs), extremely low-frequency magnetic fields (ELF-MFs), and RF-EMFs. Measurements were taken in 226 households throughout Lower Austria. In addition, effects of simple reduction measures (e.g., removal of clock radios or increasing their distance from the bed, turning off Digital Enhanced Cordless Telecommunication (DECT) telephone base stations) were assessed. All measurements were well below International Commission on Non-Ionizing Radiation Protection (ICNIRP) guideline levels. Average night-time ELF-MFs (long-term measurement from 10 pm to 6 am, geometric mean over households) above 100 nT were obtained in 2.3%, and RF-EMFs above 1000 microW/m(2) in 7.1% of households. Highest ELF-EFs were primarily due to lamps beside the bed (max = 166 V/m), and highest ELF-MFs because of transformers of devices (max = 1030 nT) or high current of power lines (max = 380 nT). The highest values of RF-EMFs were caused by DECT telephone base stations (max = 28979 microW/m(2)) and mobile phone base stations (max = 4872 microW/m(2)). Simple reduction measures resulted in an average decrease of 23 nT for ELF-MFs, 23 V/m for ELF-EFs, and 246 microW/m(2) for RF-EMFs. A small but statistically significant correlation between ELF-MF exposure and overall RF-EMF levels of R = 0.16 (P = 0.008) was computed that was independent of type (flat, single family) and location (urban, rural) of houses. Bioelectromagnetics, 2009. (c) 2009 Wiley-Liss, Inc.

1085

Synaptosome behaviour is unaffected by weak pulsed electromagnetic fields

The present study examined the effect on rat cortical synaptosomes of a 2 h exposure to 50-Hz electromagnetic fields (EMFs) with a peak magnetic field of 2 mT. We measured modifications of synaptosomal mitochondrial respiration rate, ATP production, membrane potential, intrasynaptosomal Ca(2+) concentration and free iron release. The O(2) consumption remained unvaried in exposed synaptosomes at about 2 nM O(2)/min/mg proteins; ATP production was also unchanged. The intrasynaptosomal Ca(2+) concentration decreased slowly and there was a slight, but non-significant, depolarisation of the synaptosomal membrane. Finally, the free iron release by synaptosomal suspensions, a useful predictor of neuro-developmental outcome, remained unchanged after EMF exposure. On the whole, our results indicate that the physiological behaviour of cortical synaptosomes is not affected by weak pulsed EMFs.

1086

Synchrotron X-ray experiments in pulsed high magnetic fields

Recent developments of the techniques for measurements of X-ray diffraction and X-ray absorption spectroscopy in very high magnetic fields are reviewed. Miniature pulsed magnets allow us to conduct various kinds of high-field X-ray experiments rather easily; the magnets can be readily installed on a conventional apparatus such as a diffractometer and a cryostat because of its smallness. The results of some experiments on the field-induced phase transition of a rare-earth intermetallic compound (YbInCu4) are also presented.

1087

Synergistic interaction of ultrasonic shock waves and hyperthermia in the Dunning prostate tumor R3327-AT1

Pulsed high-energy ultrasound shock waves (PHEUS), similar to those used for clinical lithotripsy, can deposit energy deep in tissue and thereby destroy the microvasculature of solid tumors. We investigated the potential of PHEUS, generated by an electromagnetic shockwave source (19 kV capacitor voltage, 1 Hz pulse frequency), as a local cancer-therapy modality alone and in combination with local tumor hyperthermia (43.5 +/- 0.1 degrees C, 30 min). Copenhagen rats transplanted with the anaplastic Dunning-prostate-tumor sub-line R3327-AT1 received 1000 PHEUS pulses, which delayed tumor growth by one tumor-doubling time (5 days). Histopathology revealed hemorrhage, disruption of tumor vasculature, and necrosis in the focus of the sound field. Bromodeoxyuridine (BUdR) incorporation was significantly lower in PHEUS-treated tumors than in controls. Dynamic magnetic resonance imaging (MRI) studies using gadolinium-DTPA as contrast agent showed a strong reduction of tumor perfusion after PHEUS treatment, although this effect was partly reversible within 3 days after PHEUS. While hyperthermia alone produced no significant delay in tumor growth, the combination of PHEUS and hyperthermia produced tumor-growth delay by 2 tumor-volume-doubling times. The maximum growth delay was achieved when PHEUS and hyperthermia were separated by 24 hr at the time of maximum perfusion reduction indicated by MRI. Thus, the cytotoxic effect of PHEUS was enhanced by hyperthermia in the anaplastic prostate tumor R3327-AT1 grown on Copenhagen rats in a synergistic manner, due to blood-flow reduction. In conjunction with other agents, such as hyperthermia, PHEUS might become a local cancer-therapy modality in solid tumors accessible to ultrasound.

1088

Synergistic role of hydroxyapatite nanoparticles and pulsed electromagnetic field therapy to prevent bone loss in rats following exposure to simulated microgravity

The purpose of the present study was to use capacitive coupling of pulsed electromagnetic field (CC-PEMF) and hydroxyapatite nanoparticles (HAp) as a countermeasure to prevent osteoporosis induced by simulated microgravity. We used the hind-limb suspension (HLS) rat model to simulate microgravity-induced bone losses for 45 days. In order to compare the resulting changes, mineralogical (bone mineral density [BMD], calcium [Ca], and phosphorus [P]), biochemical (osteocalcin, alkaline phosphatase [ALP], and type I collagen), and histological (scanning electron microscopy) parameters were adopted. As a countermeasure to the above, the effect of PEMF and HAp application were examined. Three-month-old female Wistar rats were randomly divided into control (n = 8), HLS (n = 8), HLS with PEMF (n = 8), HLS with HAp nanoparticles (n = 8), and HLS with HAp and PEMF (n = 8). We observed: 1) significant decrease (p < 0.01) in BMD, Ca, P, type I collagen, and ALP activity in femur and tibia in hind-limb bone and serum osteocalcin in HLS rats as compared with the ground control. 2) Nonsignificant increase in BMD (p < 0.1), Ca (p < 0.1), P (p < 0.5), type I collagen (p < 0.1), and ALP activity (p < 0.5) in femur and tibia in hind-limb bone and serum osteocalcin (p < 0.5) in HLS + PEMF rats compared with HLS rats. 3) Significant increase in BMD (p < 0.02), Ca (p < 0.05), P (p < 0.05), type I collagen (p < 0.02), and ALP activity (p > 0.02) in femur and tibia in hind-limb bone with a nonsignificant increase in serum osteocalcin (p > 0.1) in HLS + HAp rats compared to HLS rats. 4) Significant increase in BMD (p > 0.01). Ca (p > 0.01). P (p > 0.01). type I collagen (p > 0.01). and ALP activity (p > 0.01) in femur and tibia in hind-limb bone and serum osteocalcin (p > 0.02) were also observed. Results suggest that a combination of low level PEMF and Hap nanoparticles has potential to control bone loss induced by simulated microgravity.

1089

Synthesis of DnaK and GroEL in Escherichia coli cells exposed to different magnetic field signals

The effects of extremely low frequency magnetic field (ELF-MF)(1 mT, 50 Hz) on the heat shock protein (HSP) synthesis in Escherichia coli were investigated. Two magnetic field signals were studied: sinusoidal (SMF) and pulsed square wave (PMF). It was found that bacteria exposed to SMF showed a significantly higher level of DnaK and GroEL proteins as compared to sham-exposed bacteria as revealed by Western blot, whereas a lower level was observed after PMF exposure. Similar results were obtained when bacterial cells were exposed to heat shock (HS) after ELF-MF exposure: again SMF and PMF resulted in an increase and in a reduction of HSP amount in comparison with sham control, respectively. In conclusion, the MF influences the synthesis of HSPs in E. coli in a way that critically depends on the signal characteristics.

1090

Synthesis of electromagnetic Schell-model sources

A procedure for the synthesis of the most general electromagnetic Schell-model light source is proposed. It makes use of the generalized van Cittert-Zernike theorem to produce the electromagnetic source starting from a primary spatially incoherent source, characterized by a suitable position-dependent polarization matrix. By resorting to the spectral decomposition of the polarization matrix, it is shown how such an incoherent source can be synthesized by using a Mach-Zehnder interferometer, with suitable amplitude transmittances placed in its arms, fed by two mutually uncorrelated laser beams. Examples are given for the case of electromagnetic Gaussian Schell-model sources.

1091

Systematic variation of off-resonance prepulses for clinical magnetization transfer contrast imaging at 0.2, 1.5, and 3.0 tesla

OBJECTIVES: The aim of the presented study was to evaluate pulsed magnetization transfer contrast (MTC) effects using saturation pulses of variable off-resonance frequency and radio frequency (RF) amplitude for a variety of tissue types (white and gray matter, liver, kidney, spleen, muscle, and articular cartilage) in human subjects at field strengths of 0.2, 1.5, and 3.0 Tesla. MATERIALS AND METHODS: MTC imaging studies of the head, knee, and abdomen were performed using an adapted multiple MTC (mMTC) module in 3 healthy volunteers for all field strengths. This mMTC pulse module applies a variable Gaussian shaped magnetization transfer (MT) saturation pulse in a proton-density weighted RF-spoiled gradient echo sequence. It allows for both a flexible MT pulse design and performance of consecutive measurements with variation of amplitude and off-resonance frequency, whereas keeping other MT pulse parameters unchanged. Magnetization transfer signal ratio (MTR) maps were calculated on a pixel-by-pixel basis. Additional mMTC imaging measurements were performed using an agar-water phantom. For assessment of undesired direct saturation effects of the MT pulse on the water pool, numerical simulations based on Bloch's equations were performed and analyzed. RESULTS: The results indicate that MTR values for given MT pulses (pulse shape, off-resonance frequency and flip angle) are larger at higher magnetic field strengths. For white matter, gray matter, cartilage, and muscle, an increase of 10% to 30% was found at 3.0 T when compared with 1.5 T. Low magnetic field strength of 0.2 T led to MTR values of one third to half the values at 1.5 T. MTR values for abdominal tissues were partly lower at 3.0 T compared with 1.5 T, which might be related to reduced B1 field strengths at 3.0 T due to dielectric effects. CONCLUSIONS: The increased MT effect at a higher field strength can partly compensate the specific absorption rate related problems in MTC applications. It is shown that for flip angles of 700 degrees to 900 degrees and offset frequencies of 1000 Hz to 1500 Hz, high quality MTR maps could be obtained at an acceptable level of direct saturation for all field strengths. Furthermore, if the better signal-to-noise ratio at higher magnetic fields is taken into account, quality of MTR maps of the head and the knee at 3.0 T was clearly improved compared with lower fields under optimized and comparable conditions.

1092

Tardy effect of neurogenic muscular atrophy by magnetic stimulation

The influence of pulsed magnetic stimulation on denervated muscles was investigated in this study. Of 24 rats divided into three groups for experiment, 8 rats served as control; 16 rats with bilaterally severed sciatic nerves were divided into two groups for different modes of stimulation. Magnetic stimulation with a high power output that induced an intensive contraction of muscle was applied at one side-denervated gastrocnemius muscle for 1 mo in a group of rats; electric stimulation with high intensity at 6 Hz frequency and 1-ms pulse duration served as a contrast in the other group. Muscular weight, volume, fiber diameter and percentage of fiber types were measured after the experiment. A significant retardation of weight loss in denervated muscles via magnetic stimulation (P < 0.05) was confirmed by observed results. Type II fiber atrophy was retarded in denervated muscles by magnetic stimulation as well as in denervated muscles via electric stimulation. Magnetic stimulation, used as a method that induces muscular activity, was verified in this study as being capable of retarding denervated muscular atrophy. Its benefits of painless stimulation as well as deeply activated muscular contraction could be expected to function as a new model for rehabilitation of paralyzed muscles.

1093

Technique for microwave-induced hyperthermia in superficial human tumours

In order to induce local hyperthermia in superficial tumours a computer system using a 2,450 MHz microwave generator connected to a circular (diameter 90 mm) direct contact applicator was constructed based on invasive temperature control. Small thermistor probes with a diameter of 0.6 mm are inserted in the tumour and surrounding tissues. Eight thermistors can be used simultaneously and one of them is chosen as the "master'. The automatic control system used a pulsed irradiation technique to avoid the problem with interactions between the metallic wires of the temperature probe and the electromagnetic field. With the system it was possible to control the temperature at the master thermistor within +/- 0.5 degrees C from the preset value.

1094

Temporal and spatial variability of personal exposure to radio frequency electromagnetic fields

BACKGROUND: Little is known about the population's exposure to radio frequency electromagnetic fields (RF-EMF) in industrialized countries. OBJECTIVES: To examine levels of exposure and the importance of different RF-EMF sources and settings in a sample of volunteers living in a Swiss city. METHODS: RF-EMF exposure of 166 volunteers from Basel, Switzerland, was measured with personal exposure meters (exposimeters). Participants carried an exposimeter for 1 week (two separate weeks in 32 participants) and completed an activity diary. Mean values were calculated using the robust regression on order statistics (ROS) method. RESULTS: Mean weekly exposure to all RF-EMF sources was 0.13 mW/m(2) (0.22 V/m) (range of individual means 0.014-0.881 mW/m(2)). Exposure was mainly due to mobile phone base stations (32.0%), mobile phone handsets (29.1%) and digital enhanced cordless telecommunications (DECT) phones (22.7%). Persons owning a DECT phone (total mean 0.15 mW/m(2)) or mobile phone (0.14 mW/m(2)) were exposed more than those not owning a DECT or mobile phone (0.10 mW/m(2)). Mean values were highest in trains (1.16 mW/m(2)), airports (0.74 mW/m(2)) and tramways or buses (0.36 mW/m(2)), and higher during daytime (0.16 mW/m(2)) than nighttime (0.08 mW/m(2)). The Spearman correlation coefficient between mean exposure in the first and second week was 0.61. CONCLUSIONS: Exposure to RF-EMF varied considerably between persons and locations but was fairly consistent within persons. Mobile phone handsets, mobile phone base stations and cordless phones were important sources of exposure in urban Switzerland.

1095

The action of pulsed magnetic fields on cyclic AMP levels in cultured fibroblasts

Pulsed magnetic fields, similar to those used clinically to promote bone repair, have been applied to cultured fibroblasts obtained from chick embryo tendons and rabbit bone marrow. Cyclic adenosine monophosphate (cAMP) levels were found to be lower in field-treated cultures in response to hormones such as prostaglandin E2 and isoproterenol, and the fibroblasts appear less sensitive to environmental perturbation prior to hormone incubation. We propose that the adenylate cyclase complex is temporarily inactivated by prolonged exposure to pulsed magnetic fields, and that this effect might be analogous to desensitisation phenomena.

1096

The anticonvulsant effect of electrical fields.

The use of electrical fields to treat epilepsy is undergoing increased scrutiny as an alternative to medications and resective surgery. Much recent attention has been focused on ionic channels and seizure control; however, nonsynaptic mechanisms may be crucial for seizure onset, raising the possibility of using electrical field application to abort seizures. Furthermore, the inhibitory effects may outlast the immediate treatment and possibly be a prophylactic intervention. This paper reviews the use of brain stimulation for treatment of epilepsy, but also cites instances where the antithetical results occur. The greatest detail focuses on disrupting the onset or shortening the seizure. The paper does not extensively review deep brain or vagal nerve stimulation.

1097

The aversive effect of electromagnetic radiation on foraging bats: a possible means of discouraging bats from approaching wind turbines

Large numbers of bats are killed by collisions with wind turbines and there is at present no accepted method of reducing or preventing this mortality. Following our demonstration that bat activity is reduced in the vicinity of large air traffic control and weather radars, we tested the hypothesis that an electromagnetic signal from a small portable radar can act as a deterrent to foraging bats. From June to September 2007 bat activity was compared at 20 foraging sites in northeast Scotland during experimental trials (radar switched on) and control trials (no radar signal). Starting 45 minutes after sunset, bat activity was recorded for a period of 30 minutes during each trial and the order of trials were alternated between nights. From July to September 2008 aerial insects at 16 of these sites were sampled using two miniature light-suction traps. At each site one of the traps was exposed to a radar signal and the other functioned as a control. Bat activity and foraging effort per unit time were significantly reduced during experimental trials when the radar antenna was fixed to produce a unidirectional signal therefore maximising exposure of foraging bats to the radar beam. However, although bat activity was significantly reduced during such trials, the radar had no significant effect on the abundance of insects captured by the traps.

1098

The biological effects of a pulsed electrostatic current with specific reference to hair: electro-trichogenesis.

This double-blind, place to go controlled study investigated men with alopecia to determine effective magnetic field therapy. After 36 weeks of treatment, it was found that the hair loss was stopped and new hair growth was promoted.

1100

The Canadian experience with pulsed magnetic fields in the treatment of ununited tibial fractures

A clinical survey of 56 patients was conducted at four different centers in Canada to evaluate the effect of extremely low frequency pulsed magnetic fields (PMF) on ununited fractures of the tibia. All ten patients with delayed union and 84% of the 44 patients with nonunion healed. One case with a traumatic pseudarthrosis and one with a congenital pseudarthrosis failed to respond to treatment. These results compare favorably to those reported by others using a system with different pulse characteristics. Prolonged immobilization is necessary and poses problems of rehabilitation. Nonunions with a gap between the tibial fragments and pseudarthroses are better treated with bone grafting and internal fixation prior to electrical stimulation.

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