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- Bergqvist, Björn, 1965, et al.
(författare)
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Effect of microwave radiation on permeability of liposomes. Evidence against non-thermal leakage
- 1994
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Ingår i: Biochimica et Biophysica Acta - General Subjects. - : Elsevier BV. - 1872-8006 .- 0304-4165. ; 1201:1, s. 51-54
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Tidskriftsartikel (refereegranskat)abstract
- The effect of 2.45 GHz microwave radiation on the permeability of unilamellar phosphatidylcholine liposomes has been studied. Leakage of 5(6)-calboxyfluorescein from the liposomes was measured using spectrofluorimetry after exposure to either microwaves or thermal heating for 5-20 min intervals. The exposure temperature, 37.6 +/- 0.5 degrees C, was well above the phase transition temperature of the lipid membrane. The microwave exposure did not result in any non-thermal increase in permeability above that produced by thermal heating. This study refutes the results reported by Saalman et al. [1] in which an increased liposome permeability due to microwave exposure was reported. The refined analysis in the present study shows that this increased liposome permeability was not a non-thermal microwave effect.
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| 2. |
- Galt, Sheila, 1956, et al.
(författare)
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EXPERIMENTAL SEARCH FOR COMBINED AC AND DC MAGNETIC-FIELD EFFECTS ON ION CHANNELS
- 1993
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Ingår i: Bioelectromagnetics. - : Wiley. - 1521-186X .- 0197-8462. ; 14:4, s. 315-327
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Tidskriftsartikel (refereegranskat)abstract
- The hypothesis that specific combinations of DC and low frequency AC magnetic fields at so-called cyclotron-resonance conditions could affect the transport of ions through ion channels, or alter the kinetics of ion channels (opening and closing rates), has been tested. As a model system, the ion channels formed by gramicidin A incorporated in lipid bilayer membranes were studied. No significant changes in channel conductance, average lifetime, or formation rate as a function of applied fields could be detected over a wide range of frequencies and field strengths. Experiments were carried out to measure the time-resolved single-channel events and the average conductances of many-channel events in the presence of K+ and H+ ions. The channel blocking effect of Ca++ was also studied. (C) 1993 Wiley-Liss, Inc.
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| 3. |
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| 4. |
- Saalman, Elisabeth, 1955, et al.
(författare)
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EFFECT OF 2.45 GHZ MICROWAVE-RADIATION ON PERMEABILITY OF UNILAMELLAR LIPOSOMES TO 5(6)-CARBOXYFLUORESCEIN - EVIDENCE OF NONTHERMAL LEAKAGE
- 1991
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Ingår i: Biochimica Et Biophysica Acta. - : Elsevier BV. - 0006-3002 .- 0005-2736. ; 1064:1, s. 124-130
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Tidskriftsartikel (refereegranskat)abstract
- The influence of 2.45 GHz microwave radiation on the membrane permeability of unilamellar liposomes was studied using the marker 5(6)-carboxyfluorescein trapped in phosphatidylcholine liposomes. The release of the fluorescent marker was followed by spectrofluorimetry after an exposure of 10 minutes to either microwave radiation or to heat alone of the liposome solutions. A significant increase of the permeability of carboxyfluorescein through the membrane was observed for the microwave-exposed samples compared to those exposed to normal heating only. Exposure to 2.45 GHz microwave radiation of liposomes has been previously found to produce increased membrane permeability as compared with heating. However, in contrast to previous studies, the observations reported here were made above the phase transition temperature of the lipid membrane. The experimental setup included monitoring of the temperature during microwave exposure simultaneously at several points in the solution volume using a fiberoptic thermometer. Possible mechanisms to explain the observations are discussed.
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