Stephen F. Cleary

Effect of isothermal radiofrequency radiation on cytolytic T lymphocytes.

Previous in vitro studies provide evidence that RF electromagnetic radiation modulates proliferation of human glioma, lymphocytes, and other cell types. The mechanism of RF radiation cell proliferation modulation, as well as mechanisms for effects on other cell physiologic endpoints, are not well understood. To obtain insight regarding interaction mechanisms, we investigated effects of RF radiation exposure on interleukin 2 (IL‐2) ‐de‐ pendent proliferation of cytolytic T lymphocytes (CTLL‐2). After exposure to RF radiation in the presence or absence of IL‐2 cells were cultured at various physiological concentrations of IL‐2. Treatment effects on CTLL‐2 proliferation were determined by tritiated thymidine incorporation immediately or 24 h after exposure. Exposure to 2450 MHz RF radiation at specific absorption rates (SARs) of greater than 25 W/kg (induced E‐field strength 98.4 V/m) induced a consistent, statistically significant reduction in CTLL‐2 proliferation, especially at low IL‐2 concentrations. At lower SARs, 2450 MHz exposure increased CTLL‐2 proliferation immediately after exposure but reduced 24 h postexposure proliferation. RF radiation effects depended on the mitotic state of the cells at the time of exposure. Comparison of the effects of temperature elevation and RF radiation indicated significant qualitative and quantitative differences.—Cleary, S. F. Cleary, Du, Z., Cao, G., Liu, L.‐M., McCrady, C. Effect of isothermal radiofrequency radiation on cytolytic T lymphocytes. FASEB J. 10, 913‐919 (1996)

Stress proteins are not induced in mammalian cells exposed to radiofrequency or microwave radiation

The induction of stress proteins in HeLa and CHO cells was investigated following a 2 h exposure to radiofrequency (RF) or microwave radiation. Cells were exposed or sham exposed in vitro under isothermal (37 +/- 0.2 degrees C) conditions. HeLa cells were exposed to 27- or 2450 MHz continuous wave (CW) radiation at a specific absorption rate (SAR) of 25 W/kg. CHO cells were exposed to CW 27 MHz radiation at a SAR of 100 W/kg. Parallel positive control studies included 2 h exposure of HeLa or CHO cells to 40 degrees C or to 45 microM cadmium sulfate. Stress protein induction was assayed 24 h after treatment by electrophoresis of whole-cell extracted protein labeled with [35S]-methionine. Both cell types exhibited well-characterized responses to the positive control stresses. Under these exposure conditions, neither microwave nor RF radiation had a detectable effect on stress protein induction as determined by either comparison of RF-exposed cells with sham-exposed cells or comparison with heat-stressed or Cd++ positive control cells.

Effects of isothermal 2.45 GHz microwave radiation on the mammalian cell cycle: comparison with effects of isothermal 27 MHz radiofrequency radiation exposure

Abstract Synchronized Chinese hamster ovary (CHO) cells were exposed to continuous wave (CH) 2.45 GHz microwave radiation (MWR) or CW 27 MHz radiofrequency radiation (RFR) under isothermal conditions (37±0.2°) to test the following hypotheses: (1) high frequency electromagnetic radiation exposure directly affects the mammalian cell cycle in the absence of radiation-induced heating; and (2) the magnitude of the cell cycle alteration is frequency dependent. CHO cells in either G0/G1-, S−, or G2/M-phase of the cell cycle were simultaneously exposed to CW 27 MHz RFR or CW 2.45 GHz MWR at specific absorption rates (SARs) of 5 or 25 W kg−1, or sham exposed, at 37±0.2°C. Cell cycle alterations were determined by flow cytofluorometry over a 4 d period after exposure. The DNA distributions of RFR, MWR, and sham exposed cells were compared to detect qualitative effects on the cell cycle. Quantitative measures of the effects of isothermal radiation exposure were determined from differences in the number of exposed and sham exposed cells in various cell cycle phases as well as comparison of the mean DNA content of exposed and sham exposed cell samples. Flow cytofluorometric assay precision and accuracy were determined by comparison of DNA distributions of replicate CHO control cell samples and by the use of internal DNA standards. Exposure to 27 MHz RFR or 2.45 GHz MWR altered the CHO cell cycle for periods of up to 4 d following exposure at SARs of 5 or 25 W kg−1. There were significant differences in temporal responses, cell cycle phase sensitivity, and overall degree of cell cycle alteration for 27 MHz compared with 2.45 GHz radiation exposure. In contrast to the effect of 27 MHz RFR, which did not affect G2/M-phase CHO cells, 2.45 GHz MWR altered all cell cycle phases to varying degrees. Exposure to 2.45 GHz MWR at 5 or 25 W kg−1 was twice as effective as 27 MHz RFR in inducing cell cycle alterations as determined by differences in the number of exposed versus sham-exposed cells in various cell cycle phases.

Effects of pulsed electric fields on mouse spleen lymphocytes in vitro

The effects of pulsed electric fields on cell membranes were investigated. In vitro exposure of mouse splenocytes to a single high-voltage pulse resulted in an increase in membrane permeability that was dependent on both the electric field strength and the pulse duration. Exposure to a 2 microseconds, 3.0 kV/cm pulse resulted in the induction of a 1.26 V transmembrane potential, and elicited a 50% loss of intracellular K+. These results are in agreement with previous studies of the effects of pulsed electric fields on erythrocytes and microorganisms. The effect of pulsed electric fields on the functional integrity of lymphocytes was investigated by measuring [3H]thymidine incorporation by cells cultured in the presence and absence of various mitogens following exposure to an electrical pulse. No statistically significant effects on the response of mouse spleen lymphocytes to concanavalin A, phytohemagglutinin or lipopolysaccharide were observed following exposure to 2 microseconds electric pulses at amplitudes of up to 3.5 kV/cm. Exposure to a single 10 microseconds pulse of 2.4-3.5 kV/cm produced a statistically significant reduction in the response of lymphocytes to lipopolysaccharide stimulation that was attributed to cell death.

Modified method of mammalian cell synchronization improves yield and degree of synchronization

A modified method to synchronize CHO and HeLa cells is developed based upon a combined shaking-off and chemical blockage. This method has effectively blocked quiescent cells, which is the main obstacle of high degree synchronization. Flow-cytometry data show the improvement on the degree of synchronization and yield compared to two previously used methods.

The Effect of Threshold Macular Lesions and Subthreshold Macular Exposures on Visual Acuity in the Rhesus Monkey

The purpose of this research program was to evaluate retinal threshold burns and subthreshold exposures of the mammalian macula in terms of visual acuity. Rhesus monkeys {Macaca mulatto) were trained by a reward system to respond to the automated presentation of Landolt rings. After appropriate training, these animals were exposed to threshold and subthreshold levels of retinal energy density ranging from 3.2 to 10.7 J/cm2, exposure time approximately 135 ms. spectral quality approximately that of color temperature 6000° K with wavelengths above 900 nm removed,, and image sizes on the retina of about 1 mm in diameter, covering a major portion of the monkey macular area. Results, in terms of visual acuity decrement (monocular), indicated that energy densities on the retina below 5 J/cm2 were not statistically significant, whereas energy densities greater than 5 J/cm2 produced losses in visual acuity (monocular) which were significant. These results indicate that, at levels of energy density on the retina w...

Considerations in the Evaluation of the Biological Effects of Exposure to Microwave Radiation

The increasing use of microwave (SHF) and ultra-high-frequency (UHF) radiation in industry and in the home suggests the need for a re-evaluation of the available information concerning the biological effects of such exposures. A review of the thermal (> 10mW/cm2) and nonthermal effects of microwave and UHF exposure on organisms, organs, cells, bacteria, and biological molecules is presented, as well as the exposure limits that have been based on such data. It is suggested that the area of greatest uncertainty is the effects of nonthermal exposure on the central nervous system. Suggestions are made for additional research on the effects of nonthermal exposures at various levels of biological systems.

Effects of acute and protracted ionizing radiation on the rabbit lens.

With the advancement of manned space exploration, potentially hazardous exposure levels to ionizing radiation deriving from the continuous fields of the van Allen belt to less predictable exposures from solar flares have been of concern. While the former can be avoided to some degree by selected orbital flight patterns, solar flares may present some problems. Since the eye is a superficially located organ and its lens is a relatively sensitive biological structure, responding to ionizing radiation with characteristic changes easily observable under in vivo biomicroscopy, it lends itself particularly well to studying effects of selected dose and energy levels. T o accomplish this goal, the following investigations were conducted: