Effect of 2450 MHz microwave radiation on hematopoiesis of pregnant mice.

In this study, the influence of 2450 MHz CW microwave radiation on hematopoiesis in pregnant mice was examined. Dams (mice CD-1 strain) were irradiated during Days 1-6 or 6-15 of pregnancy. The animals were irradiated for a total of 8 hr per day (two 4-hr exposures in 9 hr) at an average power density of 30 mW/cm2. Peripheral blood and bone marrow samples were obtained on Day 18 of pregnancy. The total leukocyte and differential leukocyte counts of peripheral blood samples were not affected by either exposure regimen. In addition, no effects were noted in either the erythroid or myeloid mitotic indices of bone marrow samples. Exposure of pregnant mice to microwave radiation under the conditions of these experiments had no effects on the investigated aspects of hematopoiesis.

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.

The effect of 2450-MHz microwave radiation during microtubular polymerization in vitro.

Exposure to 2450-MHz (cw) microwave radiation causes inhibition of cell division in intact cells and varied in vivo biological effects in both avian and mammalian species. Because these reported effects may result from alterations in the dynamics of microtubule formation, we studied the effects of simultaneous microwave exposure (2450 MHz, cw) during each of the three critical stages of the intracellar polymerization cycle. In addition, using circular dichroism spectroscopy, we studied the effect of microwave irradiation on the secondary structure of purified tubulin polypeptides. These studies were accomplished using specially constructed exposure systems that permit the continuous recording of turbidometric or circular dichroism measurements during simultaneous exposure to microwaves. The baseline turbidity of microtubular protein did not change under the influence of microwave radiation (20 or 200 mW/g SAR) and irradiation had no effect on the light-scattering properties of the depolymerized protein. EGTA-induced polymerization and cold-induced depolymerization patterns were also similar for both control and microwave-irradiated samples. The circular dichroism spectrum of purified tubulin also did not appear to be influenced by microwave irradiation, indicating a lack of effect on the protein secondary structure. The data suggest that the cellular effects of microwaves are not due to changes in microtubular proteins or their rate of polymerization.

Evaluation of in vitro effects of 50 and 60 Hz magnetic fields in regional EMF exposure facilities.

A weak association between magnetic-field exposure and increased incidences of cancer has been reported. While alterations in cellular processes after in vitro magnetic-field exposures have also been reported to provide plausibility for this association, other laboratories have been unable to repeat the findings. As part of an accelerated electric- and magnetic-field (EMF) research program, the National Institute of Environmental Health Sciences with the Department of Energy identified the replication of the published positive effects as a priority. Regional EMF exposure facilities were established to investigate major in vitro effects from the literature. These included effects on gene expression, intracellular calcium, colony growth in soft agar, and ornithine decarboxylase activity. The laboratories that first reported these effects provided experimental protocols, cell lines, and other relevant experiment details. Regional facility studies included sham/sham exposures (no applied field in either chamber) and were done in a blinded fashion to minimize investigator bias. In nearly all experiments, no effects of magnetic-field exposure were found. The effort provided insight into dealing with the difficulty of replication of subtle effects in complex biological systems. Experimental techniques provided some clues for the differences in experimental results between the regional facility and the original investigator. Studies of subtle effects require extraordinary efforts to confirm that the effect can be attributed to the applied exposure.

An approach to NMR studies of the metabolism of internal organs using surface coils.

This communication describes a surgical preparation of experimental animals to permit NMR spectroscopic studies of the metabolism of internal organs. In the procedure developed, the layer of protective muscle directly above the organ is removed, but the skin is left intact. NMR studies of the metabolism of the organ can then be carried out using surface coils placed externally over the herniated area. Modified probe and stack designs for use with the surgically modified animals in a conventional NMR spectrometer are described. Phosphorus-31 NMR spectra of liver and kidney of the modified animals have been obtained, and data corresponding to the hepatic response to a load of fructose are presented.

A novel method for the study of fluorescent probes in biological material during exposure to microwave radiation.

Instrumentation has been developed which allows the monitoring of fluorescence in erythrocyte ghost membranes before, during, and after exposure to microwave radiation. Using non-fluorescent, UV-transmitting fiber optic cables, excitation light of specific wavelengths was delivered to a stirred sample undergoing irradiation (2450 MHz, CW) within a fluid-filled, temperature-controlled waveguide. Fluorescence was collected using an identical cable and transferred through appropriate filters to standard detecting, amplification and recording devices. We have used the fluorescent probe, 1-anilino-8-naphthalene sulfonate (ANS) to monitor the effect of microwave radiation on the binding of calcium to erythrocyte ghosts. Microwave radiation at specific absorption rates of 10 and 200 mW/g had no effect on the binding of ANS to the membranes. Dose-response curves also showed no influence of microwaves on calcium binding between 2.0 and 10.0 x 10(-4) M. In addition, experiments studying fluorescence energy transfer between intrinsic tryptophan residues and membrane bound ANS showed that intermolecular distances between donor and acceptor are also unaffected by microwave radiation. We have thus shown that 2450 MHz microwave radiation at the specific absorption rates used does not interfere with the binding of calcium to erythrocyte ghosts or alter intermolecular distances between intrinsic molecules and bound ANS.

Trauma induced histamine synthesis and RES activity.

The histidine decarboxylase activity of the lung and spleen was determined in animals made resistant to tumbling trauma, either by prior sublethal exposure or by injection of extracts prepared from the spleens and plasma of trauma resistant rats. The data describe the post-traumatic period in the normal animal as being associated with an increased histidine decarboxylase activity. In addition, the increased histidine decarboxylase activity was paralleled by an increased phagocytic activity of the reticuloendothelial elements of the spleen. In trauma resistant animals, changes in the enzyme activity and phagocytic capability were prevented or curtailed. The administration of spleen and plasma protective extracts were similarly effective in impeding these changes following trauma. It is suggested that the active humoral factor elaborated during conditioning and associated with the RES may act by inhibiting the activation of histidine decarboxylase.

Effects of blood contamination on equine peritoneal fluid analysis.

Peritoneal fluid and blood was collected from 8 healthy adult horses. Four 1-ml aliquots of peritoneal fluid from each horse were then contaminated with 0 ml (normal), 0.05 ml (1 drop), 0.10 ml (2 drops), and 0.20 ml (4 drops) of blood from the same horse. Samples were analyzed for RBC count, nucleated blood cell count, total protein concentration, and nucleated cell differential count. Statistical analysis revealed no significant changes in nucleated cell number, nucleated cell differential, or total protein concentration in peritoneal samples contaminated with blood. The RBC count significantly increased with blood contamination. It was concluded that up to 17% blood contamination of peritoneal fluid in clinically normal horses did not significantly alter interpretation of the nucleated cell count or protein concentration.

Hematological response of immunized and serially bled Japanese quail.

Sexually mature female Japanese quail (Coturnix coturnix japonica) were immunized by an intravenous injection with .5 ml of a 7.5% suspension of Chukar partridge (Alectoris graeca chukar) red blood cells (CRBC). Blood samples were collected either serially from one group of quail or a single time from separate groups of quail at 0 (nonimmunized), 3, 6, and 9 days post-immunization. Total anti-CRBC hemagglutinin titers (HA) were measured by a microhemagglutinin procedure. Selected hematological variables were also measured. Mean HA was not affected by serial blood sampling. Total erythrocyte numbers, percent hematocrit, and hemoglobin levels were depressed in serially bled quail at 3 days postimmunization. Reticulocytosis was found in serially bled quail at 6 days postimmunization.

Influence of acute microwave radiation on cardiac function in normal and myocardial ischemic cats.

Exposure of biological specimens to microwave radiation in vivo and in vitro has been reported to cause alterations to the cardiovascular system. In addition, microwave radiation may cause effects in damaged cardiac tissue that are not observed in normal tissue. In this study, we examined the influence of direct microwave irradiation (2.45 GHz, continuous wave) of the intact exposed heart on cardiac function in cats with and without myocardial ischemia. Myocardial ischemia was induced by occlusion of the left anterior descending coronary artery. In the sham-nonexposed and sham-plus-microwave exposed animals the coronary artery was isolated but not occluded. The exposed hearts were either irradiated at a specific absorption rate (SAR) of 30 mW/g or not irradiated, and were monitored for 5 h. At a SAR of 30 mW/g, the temperature of the exposed tissue increased at an initial rate of 0.43 degrees C/min in dead cats. However, in live animals, no increases in aortic blood temperatures occurred during irradiation. Mean arterial blood pressure, cardiac output, heart rate, plasma and myocardial creatine phosphokinase, and S-T segment were not influenced by 5 h of microwave irradiation of the myocardium in cats with or without myocardial ischemia.

Effect of suppression of endocrine or exocrine pancreatic function in hemorrhagic shock.

Somatostatin did not influence the pathologic consequences of hemorrhagic shock, but pancreatic duct ligation prevented the post-oligemic decline of arterial pressure and formation of toxic factors. These results indicate that pancreatic acinar cells release myocardial depressant factor and are important in the pathophysiology of shock.

Comparison of the cytotoxic actions of hypoxia and endotoxin in the perfused cat liver.

The isolated cat liver perfused at a constant flow with Krebs-Henseleit solution containing low-molecular-weight dextran was employed to ascertain the direct effects of hypoxia or endotoxin on hepatic integrity. Hypoxia resulted in large increases in circulating lactate dehydrogenase (LDH) activity and in amino-nitrogen concentration, whereas endotoxin at a dose of 0.75 microgram/gm liver wet weight resulted in only small changes in these variables after 150 minutes of perfusion. Perfusion pressure and perfusate pH did not change significantly in response to either intervention. Both hypoxia and endotoxin significantly compromised lysosomal stability as evidenced by large increases in circulating levels of cathepsin D, large increases in the nonsedimentable fraction of tissue cathepsin D (ie, increased percentage of free activity), and changes in the ultrastructural appearance of liver lysosomes associated with enhanced fragility (eg, swelling, increased vacuolization). Both interventions also significantly impaired phagocytosis by reticuloendothelial cells within the liver. However, neither intervention altered BSP clearance, indicative of a lack of effect on parenchymal cell clearance. These findings indicate that both endotoxin and hypoxia induce direct cellular damage within the liver; however, endotoxin exerted a more selective action on lysosomes, whereas hypoxia produced more of a diffuse cytotoxic effect.

Hepatic blood flow in acute myocardial ischemia.

Hepatic blood flow was monitored in cats during myocardial ischemia (MI). Increased plasma CPK activity, the S-T segment of the electrocardiogram, and hepatic flow was reduced by 5 h to 40% of control. The results suggest that MI can influence organs distant from the original ischemic episode.

The effect of 2450 MHz microwave radiation on histamine secretion by rat peritoneal mast cells.

Isolated rat peritoneal mast cells actively secrete histamine in response to reaginic or chemical stimulation. Mast cells were irradiated in a waveguide microwave exposure chamber at 2450 MHz with power absorptions of 8.2 and 41.0 mW/g for periods up to 3 h. These levels of microwave absorption caused no change in the morphological characteristics or viability of the cells. Irradiated mast cells were stimulated with compound 48/80, a potent, noncytotoxic histamine releasing agent. The dose response curves showed that neither prior nor simultaneous irradiation of mast cells at 37 degrees C affected 48/80-induced secretion. However, microwave power absorptions of 41.0 mW/g inhibited secretion at 44.0 degrees C. Precise measurements of the effect of heat on secretion indicated that this level of inhibition could have been produced by a radiation induced increase in cell temperature between 0.4 and 0.9 degrees C above ambient levels. Alternatively, the heat stress produced at 44 degrees C may have sensitized the cells to the electromagnetic effects of the microwave radiation. Rat peritoneal mast cells can therefore be useful as a model for the study of functioning secretory cells during microwave irradiation and can also be used to monitor the synergistic effects of cell heating during in vitro exposure.