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  • brain  (4)
  • CP  (1)
  • Microwave irradiation  (1)
  • 1
    Electronic Resource
    Electronic Resource
    The effects of hyperthermia and hyperthermia plus microwaves on rat brain energy metabolism (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 5 (1984), S. 63-70 
    Details
    ISSN: 0197-8462
    Keywords: hyperthermia ; microwaves ; brain ; ATP ; CP ; energy metabolism ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The effects of hyperthermia, alone and in conjunction with microwave exposure, on brain energetics were studied in anesthetized male Sprague-Dawley rats. The effect of temperature on adenosine triphosphate concentration [ATP] and creatine phosphate concentration [CP] was determined in the brains of rats that were maintained at 35.6, 37.0, 39.0, and 41.0°C. At 37, 39, and 41°C brain [ATP] and [CP] were down 6.0, 10.8, and 29.2%, and 19.6, 28.7, and 44%, respectively, from the 35.6°C control concentrations. Exposure of the brain to 591-MHz radiation at 13.8 mW/cm2 for 0.5, 1.0, 3.0, and 5.0 min caused further decreases (below those observed for 30°C hyperthermia only) of 16.0, 29.8, 22.5, and 12.3% in brain [ATP], and of 15.6, 25.1, 21.4, and 25.9% in brain [CP] after 0.5, 1.0, 3.0, and 5.0 min, respectively. Recording of brain reduced nicotinamide adenine dinucleotide (NADH) fluorescence before, during, and after microwave exposure showed an increase in NADH fluorescence during microwave exposure that returned to preexposure levels within 1 min postexposure. Continuous recording of brain temperatures during microwave exposures showed that brain temperature varied between -0.1 and +0.05°C. Since the microwave exposures did not induce tissue hyperthermia, it is concluded that direct microwave interaction at the subcellular level is responsible for the observed decrease in [ATP] and [CP].
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250050107
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of continuous-wave, pulsed, and sinusoidal-amplitude-modulated microwaves on brain energy metabolism (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 6 (1985), S. 89-97 
    Details
    ISSN: 0197-8462
    Keywords: CW ; pulsed ; amplitude modulation ; microwaves ; brain ; metabolism ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: A comparison of the effects of continuous-wave, sinusoidal-amplitude-modulated, and pulsed square-wave-modulated 591-MHz microwave exposures on brain energy metabolism was made in male Sprague-Dawley rats (175-225 g). Brain NADH fluorescence, adenosine triphosphate (ATP) concentration, and creatine phosphate (CP) concentration were determined as a function of modulation frequency. Brain temperatures of animals were maintained between -0.1 and -0.4°C from the preexposure temperature when subjected to as much as 20 mW/cm2 (average power) CW, pulsed, or sinusoidal-amplitude modulated 591-MHz radiation for 5 min. Sinusoidal-amplitude-modulated exposures at 16-24 Hz showed a trend toward preferential modulation frequency response in inducing an increase in brain NADH fluorescence. The pulse-modulated and sinusoidal-amplitudemodulated (16 Hz) microwaves were not significantly different from CW exposures in inducing increased brain NADH fluorescence and decreased ATP and CP concentrations. When the pulse-modulation frequency was decreased from 500 to 250 pulses per second the average incident power density threshold for inducing an increase in brain NADH fluorescence increased by a factor of 4 - ie, from about 0.45 to about 1.85 mW/cm2. Since brain temperature did not increase, the microwave-induced increase in brain NADH and decrease in ATP and CP concentrations was not due to hyperthermia. This suggests a direct interaction mechanism and is consistent with the hypothesis of microwave inhibition of mitochondrial electron transport chain function of ATP production.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250060109
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  • 3
    Electronic Resource
    Electronic Resource
    Experimental method for the hyperthermic treatment of cells in tissue culture: Initial application to pancreatic cancer cells (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 8 (1987), S. 195-202 
    Details
    ISSN: 0197-8462
    Keywords: Microwave irradiation ; hyperthermia ; pancreatic cancer ; experimental models ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Hyperthermia is attractive as a potential adjunctive modality in the treatment of cancer, especially those cancers that are more resistant to conventional modalities. In the present study, we characterized the response of two pancreatic cancer cell lines to hyperthermia alone. In so doing, we utilized and characterized a novel exposure system that heats by 915-MHz continuous wave microwave (MW) radiation, with microprocessor control of the power input via temperature monitoring of the sample and simultaneous visualization and recording of temperature parameters. Samples, consisting of cells in 25-cm2 culture flasks with 10 ml of medium, were exposed to MWs in a stripline for 1 h at MW-induced temperatures of 37, 41.5, 42.5, 43.5, or 44.5 °C. The specific absorption rate was 132 W/kg for all temperatures. In addition, 37 °C waterbath controls were concurrently run. The colony formation assay was used to assess cytotoxicity. No significant difference was found between 37 °C waterbath and 37 °C MW controls. Significant differences in the thermosensitivity of the two cell lines were found, with the most drug-sensitive cell line showing the greatest thermosensitivity. However, hyperthermia alone was not very effective as a single cytotoxic modality in either cell line. The MW-hyperthermia-induction system provided precise, automated temperature control (± 0.2 °C), and ease of utilization and data management.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250080210
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  • 4
    Electronic Resource
    Electronic Resource
    The differential effects of 200, 591, and 2,450 MHz radiation on rat brain energy metabolism (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 5 (1984), S. 419-433 
    Details
    ISSN: 0197-8462
    Keywords: radiofrequency ; brain ; metabolism ; stripline ; fluorescence ; mechanism ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Three key compounds in brain energy metabolism have been measured during and after exposure to continuous wave radiofrequency radiation at 200, 591, and 2,450 MHz. Frequency-dependent changes have been found for all three compounds. Changes in NADH fluorescence have been measured on the surface of a surgically uncovered rat brain during exposure. At 200 and 591 MHz, NADH fluorescence increased in a dose-dependent manner between approximately 1 and 10 mW/cm2, then became constant at higher exposures. There was no effect at 2,450 MHz. Levels of ATP and CP were measured in whole brain after exposure. The ATP levels were decreased at 200 and 591 MHz but not at 2,450 MHz. The CP levels decreased only at 591 MHz. The effect of duration of exposure (up to 5 min) was investigated for all compounds at 200 MHz and 2,450 MHz, and exposures to 20 minutes were examined at 591 MHz. Temperature in the rat brain was essentially constant for all exposures. A general mechanism for inhibition of the mitochondrial electron transport chain and the CP-kinase reaction pathway by radiofrequency radiation has been proposed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250050407
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  • 5
    Electronic Resource
    Electronic Resource
    Microwave effects on energy metabolism of rat brain (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 1 (1980), S. 171-181 
    Details
    ISSN: 0197-8462
    Keywords: microwaves ; in vivo ; brain ; adenosine triphosphate (ATP) ; creatine phosphate (CP) ; NADH ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Rat brain was exposed to 591-MHz, continuous-wave (CW) microwaves at 13.8 or 5.0 mW/cm2 to determine the effect on nicotinamide adenine dinucleotide, reduced (NADH), adenosine triphosphate (ATP) and creatine phosphate (CP) levels. On initiation of the in vivo microwave exposures, fluorimetrically determined NADH rapidly increased to a maximum of 4.0%-12.5% above pre-exposure control levels at one-half minute, then decreased slowly to 2% above control at three minutes, finally increasing slowly to 5% above control level at five minutes. ATP and CP assays were performed on sham- and microwave-exposed brain at each exposure time. At 13.8 mW/cm2, brain CP level was decreased an average of 39.4%, 41.1%, 18.2%, 13.1%, and 36.4% of control at exposure points one-half, one, two three, and five minutes, respectively, and brain ATP concentration was decreased an average of 25.2%, 15.2%, 17.8%, 7.4%, and 11.2% of control at the corresponding exposure periods. ATP and CP levels of rat brain exposed to 591-MHz cw microwaves at 5 mW/cm2 for one-half and one minute were decreased significantly below control levels at these exposure times, but were not significantly different from the 13.8 mW/cm2 exposures. For all exposures, rectal temperature remained constant. Heat loss through the skull aperture caused brain temperature to decrease during the five-minute exposures. This decrease was the same in magnitude for experimental and control subjects. Changes in NADH, ATP, and CP levels during microwave exposure cannot be attributed to general tissue hyperthermia. The data support the hypothesis that microwave exposure inhibits mitochondrial electron transport chain function, which results in decreased ATP and CP levels in brain.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250010207
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