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At least 1,333 records · Page 74Linked to original sources
PubMed1975

Possible physical substrates for the interaction of electromagnetic fields with biologic membranes.

A quantized electrochemical model of a greater membrane concept that comprises the neuronal phospholipid sheet of the plasma membrane and the constituents of the intercellular spaces in brain tissue is proposed as a basis to explain several recent experimental results that concern the interaction of electromagnetic fields with the central nervous system. These fields consist of gradients far below those needed for direct intervention with action potentials or chemical transmitters at synaptic sites. Problems associated with the rectification of modulated signals and transduction into brain tissue are also briefly considered.

Brain↗
PubMed1977

Migrating birds respond to Project Seafarer's electromagnetic field.

Radar tracking of individual migrating birds flying over a large alternating-current antenna system showed that the birds turned or changed altitude more frequently when the antenna system was operating than when it was not. These results suggest that birds sense low-intensity alternating-current electromagnetic fields during nocturnal migratory flight.

Animals↗
PubMed1987

Possible learned detection of exogenous brain frequency electromagnetic fields: a case study.

Zener card representations were presented visually for 15 sec. every 30 sec. for a total of 40 trials per session over 17 sessions to a single subject who displayed temporal lobe lability. During the 15 sec. before the presentation of one of the symbols (target) either a specific 4-Hz magnetic field pattern or a 1-Hz or 7-Hz magnetic field was presented bilaterally at the level of the temporal lobes. Field strengths were in the order of milligauss (about 1000X background values). The subject was required to anticipate the next symbol for each trial. Only when the 4-Hz field preceded the target symbol did the subject's accuracy of guessing remain systematically above (50%) chance (20%) over the sessions. These results suggest that exogenous magnetic fields may become discriminative stimuli through temporal association. Evidence of habituation was also obtained.

Brain↗
PubMed2002

Effect of electromagnetic fields and early postoperative 5-fluorouracil on the healing of colonic anastomoses.

BACKGROUND AND AIMS: Studies have indicated a deleterious effect of perioperative 5-fluorouracil (5-FU) administration on the healing of intestinal anastomoses. This study examined the effect of early postoperative 5-FU on the healing of colonic anastomoses and investigated the effect of electromagnetic fields (EMF) on colonic anastomotic repair under normal physiological conditions and in the presence of 5-FU therapy in a rat model. MATERIALS AND METHODS: Forty male Wistar rats were randomly assigned into four groups and underwent a standardized left colonic resection and anastomoses. The animals then served as control or received intraperitoneal 5-FU (20 mg/kg per day, 5 days), EMF stimulation (10.76 mT, 50 Hz; 2-h on/10-h off cycles, 7 days) or both, starting on the day of surgery. After 7 days anastomotic healing was assessed by measurement of hydroxyproline content and breaking strength. RESULTS: Hydroxyproline content increased in EMF exposed group (1.53+/-0.11 to 1.92+/-0.11 microg/mg) and in EMF + 5-FU group (1.53+/-0.11 to 1.89+/-0.12 microg/mg). Breaking strength also increased in the EMF group (0.23+/-0.02 to 0.27+/-0.01 MPa) and in the EMF + 5-FU group (0.23+/-0.02 to 0.28+/-0.01 MPa. No differences were found in hydroxyproline content or breaking strength between the 5-FU group and controls. CONCLUSION: Early postoperative 5-FU administration did not impair the healing of colonic anastomoses in rats. Additionally, EMF stimulation provided a significant gain in colonic anastomotic strength, in rat intestines in control animals and in animals exposed to 5-FU.

Anastomosis, Surgical↗
PubMed1988

Weak low frequency electromagnetic fields and chick embryogenesis: failure to reproduce positive findings.

Fertilised chicken eggs were incubated for 48 hours while exposed to pulsed trains of magnetic fields having a duration of 0-5 ms, a rise time of 42 microsecond, and a pulse repetition rate of 100 at a magnetic field flux density of 1 microT. Some eggs were exposed to 1,552 rad X-rays as a positive control. After exposure the embryos were scored blind for a variety of morphological features. X-irradiated eggs displayed highly significant and repeatable anatomical alterations. There were no differences between magnetic field-exposed, sham-exposed and control eggs.

Animals↗
PubMed1985

Induction heating and operator exposure to electromagnetic fields.

Alternating magnetic fields are used in industry for induction heating of metals and semiconductors. Relatively high power, typically of a few to a few hundred of kW is used, and a frequency of operation ranges from 60 Hz to a few tens of MHz. A survey of the magnetic field strengths to which the operators are exposed has shown that these exposures are, in many instances, high compared with recommended exposure limits.

Electromagnetic Fields↗
PubMed1993

Increase in nitric oxide and cyclic GMP of rat cerebellum by radio frequency burst-type electromagnetic field radiation.

1. Using rat cerebellum supernatant, the effects of radio frequency (RF) burst-type electromagnetic (EM) field radiation on the production of cyclic GMP were examined under various conditions. The radiation was generated by a generator coil, and set at a 10 MHz radiation frequency, a 50% burst time, a 10 kHz burst rate and a 5 V peak-to-peak generator voltage. 2. When the cerebellum supernatant was incubated with both exogenous L-arginine (nitric oxide (NO) donor) and NADPH, and irradiated by an RF burst-type EM field, the production of cyclic GMP was increased significantly from a level of 21-22 nmol min-1 (g tissue)-1 to 25-26 nmol min-1 (g tissue)-1. By contrast, such an effect was not found when the cerebellum supernatant was irradiated by an RF volley-type EM field. 3. When neither L-arginine nor NADPH were added to the cerebellum supernatant, the production of cyclic GMP was lowered to a level of 6 nmol min-1 (g tissue)-1 and the radiation effect was not found. When the cerebellum supernatant was chelated with EDTA, the production of cyclic GMP was lowered to a level of 7 nmol min-1 (g tissue)-1 and the radiation effect was not found. 4. Incubation with Methylene Blue, a guanylate cyclase inhibitor, lowered the production of cyclic GMP to a level of 10-12 nmol min-1 (g tissue)-1, and the radiation effect did not occur. On incubation with a NO synthase inhibitor, either NG-methyl-L-arginine or N omega-nitro-L-arginine methyl ester, the production of cyclic GMP was lowered to a level of 10-12 nmol min-1 (g tissue)-1 or 5-9 nmol min-1 (g tissue)-1 respectively, and the radiation effect was not observed. 5. Using electrochemical NO probes, the production of NO in the cerebellum supernatant was detected. The concentration of NO increased gradually after the onset of the EM field radiation. The radiation effect persisted, and reached a maximum after the cessation of the radiation. 6. In an in vivo study, the arterioles of the frog web were dilated by the radiation, and this radiation effect was almost completely abolished by the addition of a NO synthase inhibitor. This indicates that radiation activates NO synthase and ultimately induces vasodilatation.

Amino Acid Oxidoreductases↗
PubMed2002

Electromagnetic fields for bone healing.

Electrical stimulation has been applied in a number of different ways to influence tissue healing. Most of the early work was carried out by orthopedic surgeons looking for new ways of enhancing fracture healing, particularly those fractures that had developed into nonunions. Electrical energy can be supplied to a fracture by direct application of electrodes or inducing current by use of pulsed electromagnetic field or capacitive coupling. Many of these techniques have not been standardized, so interpretation of the literature can be difficult and misleading. Despite this, there have been a few good laboratory and clinical studies to investigate the effect of electrical stimulation on fracture healing, which are reviewed. These do not permit recommendation or rejection of the technique per se; however, there is some room for optimism. The authors present some of the guidelines for using this treatment modality but suggest that all treatment should be carried out as part of a clinical trial in order to generate reliable data.

Journal Article↗
PubMed1981

[Glycosaminoglycans in the brain of rats subjected to electromagnetic field action].

Investigations on changes of glucosaminoglycans content were carried out in the brain of the rats irradiated once (30 min.) or several times (2-6 hours daily). The following frequencies of e-m fields were used: 2880 MHz (pulse modulation 1000 Hz, pulse duration 1,5 mus); 150 MHz (50 V/m); 175 MHz (150 V/m); 3000 MHz c.w. continuous wave). Control groups of animals were not subject to irradiation. Statistically significant increase of GAG content was found in the brain of the rats, irradiated in e-m field of frequency 2880 MHz in comparison with GAG concentration in the controls. In the brains of animals exposed to e-m fields of frequencies 150 and 175 MHz a statistically significant decrease of GAG content was noted in comparison with GAG content in the controls. Whereas e-m field of frequency 3000 MHz c.w. did not induce statistically significant changes in GAG content in experimental animals as compared with the controls.

Animals↗