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PubMed1989

[5-HT contents change in peripheral blood of workers exposed to microwave and high frequency radiation].

The relationship between 5-HT contents in peripheral blood and power density among workers exposed to microwave or high frequency radiation in the workshops were studied. At the same time, systems and disorder of central nervous system and cardiovascular system were examined. The results of study showed that the average 5-HT content in whole blood for high frequency radiation exposure group was lower than that of the control, but without statistical significance. Value for the microwave exposure group was significantly lower than that of the control (P less than 0.01). The 5-HT content of mechanical maintainers exposed to microwave of high frequency radiation were all lower than the contents of their corresponding control groups (P less than 0.01). But for the mechanic operators as compared with their corresponding control, no significant difference was found (P greater than 0.05). The power density exposed by the maintainers of both tested groups were all higher than that of the operators. The 5-HT contents in the whole blood were inversely proportional to the power density of microwave and high frequency groups. The incidence of neurasthenic syndrome, unsymmetric skin temperature in both limbs and hypotension was higher in the microwave and high frequency radiation groups than that in the control group. The incidence of bradycardia and some abnormal items of electrocardiograph in the microwave group was obviously greater than that in high frequency group, which may be related to different frequency exposed for these two exposure groups. Whether it is related to the contents of 5-HT needs further investigation.

Adult↗
PubMed1989

Induction of neoplastic transformation in C3H/10T1/2 cells by 2.45-GHz microwaves and phorbol ester.

C3H/10T1/2 cells were exposed to 2.45-GHz microwaves for 24 h and/or 1.5 Gy of 238-kVp X rays at 3.75 Gy/min. Transformation frequency and cell survival were measured with or without postirradiation addition of the tumor promoter tetradecanoyl-phorbol-13-acetate (TPA) at 0.1 microgram/ml. We previously reported (Carcinogenesis 6,859-864, 1985) an enhancement of transformation frequency when 10T1/2 cells exposed to a special sequence of microwaves and X rays were subsequently cultured in TPA. The same sequence of microwaves and X rays without promotion resulted in a transformation response similar to that induced by X rays alone. We now report statistically significant (at P greater than 0.999) enhancement of transformation response by TPA in cells exposed to 2.45-GHz microwaves (SAR = 4.4 W/kg). Microwaves alone had no effect on transformation. Plating efficiency and cell survival were not affected by TPA or microwave treatments.

Animals↗
PubMed1988

Microwave challenges to the thermoregulatory system.

The results of several kinds of experiments have been introduced as evidence in support of the thesis that the thermoregulatory system of endotherms functions no differently in the presence of microwaves than it does in the presence of conventional sources of thermal energy. The thermoregulatory profile, unique for each species, provides the framework for the argument. The results of our experiments have demonstrated the equivalence between T and microwave intensity as they influence individual responses of heat production and heat loss. This equivalence, in turn, allows the prediction of specific alterations in thermoregulatory responses when microwaves are present. Predictions of this kind are possible because the hierarchy of autonomic responses available to any given species is always the same. This fact should provide some comfort to those who profess concern abut the uniqueness of absorbed radiofrequency energy and its fate within the body. Additional comfort can be derived from the demonstration that changes in thermoregulatory responses in the presence of microwaves depend upon the integral of energy absorption by the whole body, not upon energy deposited in some restricted locus such as the PO/AH. It is clear that the circulatory system plays a major role in the distribution of energy deposited during such exposures, a fact already emphasized by others (Burr and Krupp, 1980; Way, et al., 1981; Stolwijk, 1983; Krupp, 1983). This fact does not negate the presence of electrical hotspots as predicted on theoretical grounds (e.g, Kritikos and Schwan, 1979) or as demonstrated dosimetrically (e.g., Guy, 1971), but it does deemphasize their importance as potential deterrents to the efficient mobilization of thermoregulatory responses. The utility of the thermoregulatory profile in research of the kind described here cannot be overemphasized. Accurate profiles have been determined for most of the commonly-used laboratory animals as well as for human beings. In the broader sense, such profiles should serve as fundamental data to the design of any experiment in which microwaves may be present. For example, the normal "room temperature" for clothed human beings lies well below the LCT of most laboratory species and such a Ta may exert a substantial influence over diverse behavioral responses, drug effects, etc. as well as basic thermoregulatory responses (Adair, et al., 1983). This paper has demonstrated that by considering the thermoregulatory profile, microwave challenges to the thermoregulatory system assume their proper position within the fundamental science of thermal physiology.

Animals↗
PubMed1988

Reduced exposure to microwave radiation by rats: frequency specific effects.

Previous research has shown that SAR "hotspots" are induced within the laboratory rat and that the resulting thermal hotspots are not entirely dissipated by bloodflow. Two experiments were conducted to determine if hotspot formation in the body and tail of the rat, which is radiation frequency specific, would have behavioral consequences. In the first experiment rats were placed in a plexiglas cage one side of which, when occupied by the rat, commenced microwave radiation exposure; occupancy of the other side terminated exposure. Groups of rats were tested during a baseline period to determine the naturally preferred side of the cage. Subsequent exposure to 360-MHz, 700-MHz or 2450-MHz microwave radiation was made contingent on preferred-side occupancy. A significant reduction in occupancy of the preferred side of the cage, and hence, microwaves subsequently occurred. Reduced exposure to 360-MHz and 2450-MHz microwaves at 1, 2, 6 and 10 W/kg were significantly different from 700-MHz microwaves. In the second experiment semichronic exposures revealed the threshold for reduced exposure of 2450-MHz microwaves to be located between whole-body SAR's of 2.1 and 2.8 W/kg.

Animals↗
PubMed1986

Effects of microwaves on the adrenal cortex.

Six-hundred-and-one male Long-Evans rats were used to study the effect of microwaves on adrenocortical secretion. Power density ranged from 0.1 to 55 mW/cm2 (SAR 0.02 to 11 W/kg). The microwave signal was 2.45 GHz amplitude modulated at 120 Hz. Serum corticosterone (CS) concentration was used as an index of adrenocortical function. Ten different exposure protocols were used to identify confounding factors influencing the sensitivity of adrenal cortex to microwave exposure. Increases in CS concentration were proportional to power density or colonic temperature and inversely proportional to the baseline CS. Increased CS concentration was never observed without increased colonic temperature and was not persistent 24 h after exposure. Acclimation (reduction in magnitude of response) could be noted after the tenth exposure. Facilitated heat loss attenuated the magnitude of CS increases by limiting the degree of hyperthermia. Ethanol enhanced the hyperthermic response and desensitized the adrenal response to microwave hyperthermia by increased baseline CS. Ether stimulated adrenal secretion irrespective of previous microwave exposure or adrenal stimulation induced by microwaves. Minor inhibition was also noted occasionally as decreased CS concentration at lower intensity (less than 20 mW/cm2) and decreased postexposure urinary CS excretion at 40 mW/cm2. Adrenal stimulation required minimally a 20 mW/cm2 (4 W/kg) or 0.7 degrees C increase in colonic temperature. An SAR lower than 4 W/kg may stimulate adrenal secretion by potentiating the hyperthermic effect if the ambient temperature is well above 24 degrees C.

Adrenal Cortex↗
PubMedDate not supplied

Glutathione concentration and peptidase activity in the lens after exposure to microwaves.

This study was undertaken for observation of early changes in glutathione concentration and the activity of carboxypeptidase A and aminopeptidase in the cortex and core of the lens as well as for determination of the cumulating effect of microwave energy after repeated exposures to microwaves. Experiments were carried out on New Zealand rabbits. The control group was compared to experimental groups exposed every day for 5 minutes to microwave irradiation of the eyeballs at power densities of 5 X 10(-3) W/cm2 and 10 X 10(-3) W/cm2 during 10, 20 and 30 days. Differences were found between the control group and the groups of animals exposed to microwaves in which the glutathione concentration in the cortex and core of the lens was decreasing with time in proportion to the number of exposures. Parallelly to the number of days of exposure to microwaves the enzymatic activity of carboxypeptidase A and aminopeptidase increased in the cortex of the lens. The observed changes demonstrate cumulation of the absorbed microwave energy leading to changes in the permeability of the capsule and membranes of lenticular fibres which lead to secondary metabolic disturbances in the lens of the eye.

Aminopeptidases↗
PubMed1985

Effects of microwave cooking/reheating on nutrients and food systems: a review of recent studies.

Microwave-oven technology has been improved by the use of low power. With the utilization of low-power techniques, studies showed equal or better retention of nutrients for microwave, as compared with conventional, reheated foods for thiamin, riboflavin, pyridoxine, folacin, and ascorbic acid. Beef roasts microwaved at "simmer" were comparable with conventionally cooked roasts in sensory quality, while vegetables cooked by an institutional (1,150 w) microwave oven were superior to those cooked in a domestic (550 w) microwave oven. Microwave-cooked bacon had lower levels of nitrosamines than conventionally cooked bacon; however, the use of a new alpha-tocopherol coating system has been found to be a safe N-nitrosamine inhibitor regardless of cooking method used.

Animals↗
PubMed1985

Teratogenic, biochemical, and histological studies with mice prenatally exposed to 2.45-GHz microwave radiation.

Pregnant CD-1 mice were exposed to 2.45-GHz continuous wave microwave radiation at an incident power density of 30 mW/cm2. The local specific absorption rate near the uterine area (deep colonic location), as determined from time-temperature profiles measured with a Vitek thermistor probe, was 40.2 mW/g. Groups of mice were exposed 8 hr per day through Days 1-6 or 6-15 of pregnancy. Other groups of animals were exposed to an elevated ambient temperature of 31 degrees C which increased the colonic temperature 2.3 degrees C, the same as that produced by the microwaves. Sham-irradiated groups of animals were treated exactly the same as the microwave-exposed animals. For the two conditions, temperature exposed and sham exposed, two groups of animals were used. One group was handled in the same manner as the microwave-irradiated group and the other group was not handled so as to evaluate the effects of stressing the animals by handling. Eleven groups of animals were used in the complete study: five groups for gestational Days 1-6, five groups for gestational Days 6-15, and one group of cage control animals. On Day 18 of gestation the dams of all experimental groups were sacrificed and their reproductive status was determined. The fetuses were examined for visceral and skeletal alterations. Brain cholinesterase activity and histology were evaluated in the groups exposed on Days 6-15. The results show that microwave radiation increases embryo lethality at the early stages of gestation (exposure Days 1-6). Fetal toxicity and teratogenicity were not significantly increased by exposure to microwaves on either Days 1-6 or 6-15 of gestation. Cholinesterase activity and histology of the brain of 18-day-old fetuses were not adversely affected.

Abnormalities, Radiation-Induced↗
PubMed1983

[Tumor suppressing effect of systemic hyperthermia with 2350 MHz microwaves combined with 5-fluorouracil in mice].

C3H/He mice were inoculated i.p. with syngeneic MM2 tumor cells (2 X 10(6) cells/mouse), and they were subsequently treated by systemic hyperthermia with microwave irradiation (2450 MHz) alone, administration of 5-FU alone, or a combination of the both. The mice were exposed to hyperthermia for 5 minutes everyday with an output of 10, 20 or 30 watts. 5-FU was administered i.p. for 3 days at dose levels of 2.5 mg/kg, 5 mg/kg or 10 mg/kg body weight. The mean survival time and the mean relative body weight were recorded. From these data, tumor-suppressing effects of the treatments were analyzed by one-way variance analysis or two-way variance analysis. The mice treated with microwave irradiation alone or 5-FU alone survived significantly longer than the control mice receiving no treatment (P less than 0.01). However, no significant difference in mean survival time was observed between the microwave group and the 5-FU group. The mean relative body weight was similar among the microwave, the 5-FU and the control group. When the mice were treated with microwave irradiation and 5-FU, significant difference was observed in the mean survival time (P less than 0.01), and the combination of microwave irradiation with an output of 20 W and 10 mg/kg of 5-FU seemed to be optimal. Determination of an optimal combination was difficult with the mean relative body weight, because body weight decreased due to side effect of the combination therapy.

Animals↗
PubMed1984

[Are microwaves a co-teratogen? Experimental model concept and its verification].

Microwave radiation does not result in development of congenital malformations in mice until hyperthermia is evoked. However, in the literature it is well established that certain environmental and occupational factors not being teratogenic per se may enhance and/or influence potency of established teratogens. As concerns the microwave radiation there are results suggesting cocarcinogenic properties of this radiation. In view of the above we set the hypothesis that microwave radiation may also interfere with teratogenic potency of the established teratogens. For the experiment we selected cytosine arabinoside (ara-C) under the trade name of Cytosar, produced by the Upjohn Co. The scheme of our experiment included injection of pregnant mice with 10 mg per kg of are-C on various days of gestation and further also irradiation in microwaves fields at power density of 10 mW/cm2. After checking the teratogenic potency of ara-C in further study on combination of ara-C and microwaves all the mice from the experimental groups were injected on the 9th day of gestation. The significant increase of the incidence of both malformations and resorptions was observed after combined action of are-C and microwaves. We conclude that the experimental pattern of teratogenic action of are-C can be used widely in experiments on combination with other environmental and occupational factors.

Abnormalities, Drug-Induced↗
PubMed1982

Effect of freezing and microwave thawing on the stability of six antibiotic admixtures in plastic bags.

The stability of six antibiotics in intravenous fluids in polyvinyl chloride containers after freezing and microwave-thawing is reported. Tobramycin sulfate 160 mg, amikacin sulfate 1 g, ticarcillin disodium 3 g, clindamycin phosphate 300 mg, nafcillin sodium 1 g, and ampicillin sodium was also diluted in plastic bags of 0.9% sodium chloride injection 50 ml. For each antibiotic except ampicillin sodium, three bags were prepared and assayed immediately for antibiotic content. Two of the bags were frozen at -20 degrees C for 30 days and then thawed, one by exposure to room-temperature air and the other by microwave radiation. Each was assayed immediately and after 8 and 24 hours storage at room temperature. The third bag was not frozen, but was stored at room temperature and assayed at 8 and 24 hours. Five bags of ampicillin sodium were prepared-three in 0.9% sodium chloride, which were frozen at -20, -30, and -70 degrees C, and two in 5% dextrose, which were frozen at -30 and -70 degrees C. All ampicillin solutions were stored 30 days, assayed, microwave-thawed, and assayed again. All antibiotics except ampicillin retained 90% or more potency when microwave-thawed after storage at -20 degrees C for 30 days, and after subsequent storage at room temperature for 24 hours. Ampicillin sodium was stable in 0.9% sodium chloride when stored at -30 or -70 degrees C, microwave-thawed, and stored up to eight hours at room temperature. Ampicillin sodium was stable in 5% dextrose when stored at -70 degrees C and microwaved-thawed, but its potency declined to 70.5% after eight hours storage at room temperature.

Anti-Bacterial Agents↗
PubMed1980

Behavioral effects of chlorpromazine and diazepam combined with low-level microwaves.

Previous research findings on the interaction between drugs and microwave radiation were extended to chlorpromazine and to diazepam. The drugs were combined with a 1 mW/cm2 pulsed microwave field (2.8 GHz) and effects were measured on a fixed interval (FI 1) schedule of food reinforcement with rats. Dose-effect functions with and without sham irradiation were established for each drug. At effective doses chlorpromazine consistently decreased rate of responding and reduced with-interval response patterning. Low to moderate doses of diazepam produced little change or increases in response rate, and higher doses produced a decline in response rate. Response patterning within intervals was reduced by increasing doses of diazepam. The animals were exposed to the microwave field alone before test sessions combining the drugs with microwave radiation. Microwave exposure alone did not affect FI performance. Microwave radiation in combination with either drug did not produce any alterations in the dose-effect functions.

Animals↗
PubMed1980

Behavioral effects of microwaves.

Microwaves can produce sensations of warmth and sound in humans. In other species, they also can serve as cues, they may be avoided, and they can disrupt ongoing behavior. These actions appear to be due to heat produced by energy absorption. The rate of absorption depends on the microwave parameters and the electrical and geometric properties of the subject. We, therefore, cannot predict the human response to microwaves based on data from other animals without appropriate scaling considerations. At low levels of exposure, microwaves can produce changes in behavior without large, or even measureable, changes in body temperature. Thermoregulatory behavior may respond to those low levels of heat, and thereby affect other behavior occurring concurrently. There are no data that demonstrate that behavioral effects of microwaves depend on any mechanism other than reactions to heat. Our interpretation of whether a reported behavioral effect indicates that microwaves may be hazardous depends on our having a complete description of the experiment and on our criteria of behavioral toxicity.

Absorption↗
PubMed1994

[Effect of microwave irradiation on biological systems].

Use of microwave radiation as a source of energy has been increased in recent years. The existence of high-power microwave emitting sources, such as satellite and television communications systems, radar systems and heating devices, in both the general public and industrial environments raises the question of whether exposure to microwave radiation is detrimental to health. The use of microwave devices in home and in medicine, e.g. in clinical diagnosis and in therapy, also makes the investigation of the biological effects of acute and repetitive exposure imperative. In this work we present some characteristics of microwave radiation, and the possible effects on some systems under the conditions of different forms of microwave irradiation, on experimental animals and on the people who have been professionally or ignorantly irradiated.

Animals↗
PubMed1993

[An experimental study of catheter ablation using microwave energy via coaxial electrode catheter].

The purpose of this study was to examine the efficacy, arrhythmogenicity, and the size of ablated lesions of catheter ablation with microwave energy. Microwave energy generated by a device with a frequency of 2450 MHz, was delivered via a bipolar electrode coaxial catheter with an electrode ball tip. Microwave ablation was applied (50 watts for 15-150 sec.) on the left ventricular endocardium in 6 dogs. No ventricular arrhythmia occurred during ablation in any of the dogs when microwave catheter ablation was applied for less than 45 sec. However, when the duration of microwave catheter ablation was longer than 45-60 sec, ventricular premature contractions were observed in all 6 dogs. When ablation time was set for a longer time, the dogs developed nonsustained ventricular tachycardias. Nevertheless, ventricular arrhythmias after ablation did not occur in all dogs. Ventricular programmed stimulation after ablation did not induce ventricular tachycardia in any of the dogs. When ablation time lasted more than 120 sec, the coagulation layer was extended to the epicardium in all 6 dogs. The results of this study suggest that microwave ablation is feasible for the treatment of tachyarrhythmias from a deep focus of the ventricular myocardium.

Animals↗
PubMed1994

Athermal alterations in the structure of the canalicular membrane and ATPase activity induced by thermal levels of microwave radiation.

Sprague-Dawley rats (200-250 g) were exposed 30 min/day for 4 days to thermogenic levels (rectal temperature increase of 2.2 degrees C) of microwave radiation [2.45 GHz, 80 mW/cm2, continuous-wave mode (CW)] or to a radiant heat source resulting in an equivalent increase in body temperature of 2.2 degrees C. On the fifth day after the 4 days of exposure to microwave radiation, the animals were sacrificed and their livers removed. The canalicular membranes were isolated and evaluated for adenosinetriphosphatase (ATPase) activity, total fatty acid composition and membrane fluidity characteristics. Mg(++)-ATPase activity (Vmax) decreased by 48.5% in the group exposed to microwave radiation, with no significant change in the group exposed to radiant heat. The decrease in Mg(++)-ATPase was partially compensated by a concomitant increase in Na+/K(+)-ATPase activity (170% increase in Vmax over control) in animals exposed to microwave radiation, while no change occurred in the group exposed to radiant heat. This alteration in ATPase activity in the group exposed to microwave radiation is associated with a large decrease in the ratio of saturated to unsaturated fatty acids. Conversely, the group exposed to radiant heat had an increase in the ratio of saturated to unsaturated fatty acids. The most dramatic changes were found in the levels of arachidonic acid. Finally, the electron paramagnetic resonance (EPR) spin label technique used to measure the fluidity of the canalicular membranes of the animals in the three groups (sham, microwave radiation and radiant heat) indicated that the results were different in the three groups, reflecting the changes found in their fatty acid composition. The physiological response to "equivalent" thermal loads in rats is expressed differently for different types of energy sources. Possible mechanisms producing these divergent thermogenic responses are discussed.

Animals↗
PubMed1996

Effect of microwaves on survival of some bacterial strains.

While the inhibitory effect of microwave radiation on microorganisms is being researched intensively, how microwave radiation brings about this effect has been a matter of discussion. Some researchers support that this effect is of a thermal character, whereas some others maintain a non-thermal effect. In this work, 1 ml suspensions of Pseudomonas aeruginosa, Pseudomonas acidovorans staphylococcus aureus and Staphylococcus epidermidis bacteria were subjected to microwave radiation at 2450 MHz and 550 Watts for periods of 5, 6, 7, 8, 10, 12, 14, 16, 18, 20, 25 and 30 seconds. When each result was compared with the CFU/ml results obtained from unradiated control group bacterial suspensions derived from stock cultures, significant conclusions were attained (P < 0.001). The same experiments were repeated with the application of conventional heating. The difference between the CFU/ml values of similar bacterial suspensions subjected to microwave radiation and conventional heating was significant (P < 0.001). Concurrently, the fact that the effect was exacerbated upon increasing of liquid volume during the application of microwave radiation was established via the results obtained through the application of microwave radiation to 1 ml and 5 ml bacterial suspensions (P < 0.001).

Colony Count, Microbial↗
PubMed1998

The in vitro bactericidal effect of microwave energy on bacteria that cause prostatitis.

OBJECTIVES: We investigated the in vitro nonthermal effects of microwaves delivered from Prostatron 2.0 on Escherichia coli and Enterobacter cloacae. METHODS: The fingers of powder-free, sterile gloves were ligated, and bacterial solutions were transferred into the remaining area of the glove. The gloves were then sealed using silk ligatures. One set of gloves was subjected to the microwave treatment while another set was placed in a temperature-matched waterbath to act as control samples. The gloves containing the treatment group were taped around the probe, at the site where microwave energy exits the probe. During the treatment period, the temperatures from the urethral probe and the rectal probe were carefully monitored. RESULTS: The mean (+/-SD) energy delivered was 46.6 +/- 9.5 kJ (range 30.0 to 59.5) for the 10 trials on E. coli and colony counts in the experimental microwaved gloves decreased significantly compared with control samples (5.26 +/- 4.5 x 10(5) versus 10.16 +/- 9.3 x 10(5) CFU/mL, P = 0.02). For the experiments on E. cloacae the mean (+/-SD) energy applied was 38.5 +/- 12.5 kJ, and a significant decrease in colony counts of microwaved samples was also observed compared with controls (11.04 +/- 4.8 x 10(5) versus 20.08 +/- 10.1 x 10(5) CFU/mL, P = 0.004). CONCLUSIONS: Microwave energy, delivered from Prostatron 2.0, independent of heat production has an in vitro bactericidal effect on laboratory-cultured E. coli and E. cloacae.

Colony Count, Microbial↗