Fluorescence depolarization studies of the phase transition in multilamellar phospholipid vesicles exposed to 1.0-GHz microwave radiation.

PAPER pubmed Bioelectromagnetics 1982 In vitro study Effect: no_effect Evidence: Low

Read original paper → DOI: 10.1002/bem.2250030304 PMID: 7126281 Evidence Lab

Abstract

The phase transition in multilamellar dimyristoylphosphatidylcholine (DMPC) vesicles was studied during exposure to continuous wave 1.0-GHz microwave radiation. Fluorescence depolarization measurements using a lipid-seeking molecular probe, diphenylhexatriene (DPH), were performed as a function of temperature. Semilog plots of microviscosity versus temperature illustrate the phase transition which shows a 5 degree C shift when the vesicles are treated with chloroform as a positive control. No shift of the phase transition was found during exposure to microwave radiation at specific absorption rates between 1 and 30 W/kg. Samples were exposed in a rectangular transmission line (TEM cell), and specific absorption rates were calculated from electrical measurements of incident, reflected, and transmitted power. Samples were exposed to increasing intensities of radiation, while the temperature was maintained at either 23.5 or 25.5 degree C; these temperatures represented the two ends of the phase transition region for these vesicles. No statistically significant difference was found between exposed and control samples. These results are in contrast to those of others using laser Raman spectroscopy to measure the phase transition in similar multilamellar vesicles exposed to microwave radiation.

AI evidence extraction

At a glance

Study type

In vitro study

Effect direction

no_effect

Population

Multilamellar dimyristoylphosphatidylcholine (DMPC) vesicles (with DPH fluorescence probe)

Sample size

—

Exposure

RF · 1000 MHz

Evidence strength

Low

Confidence: 78% · Peer-reviewed: yes

Main findings

No shift of the phase transition was found during continuous-wave 1.0-GHz microwave exposure at specific absorption rates between 1 and 30 W/kg. No statistically significant differences were observed between exposed and control samples when temperature was maintained at 23.5°C or 25.5°C.

Outcomes measured

Phase transition temperature/shift in multilamellar DMPC vesicles
Microviscosity vs temperature (fluorescence depolarization using diphenylhexatriene, DPH)
Differences between exposed and control samples (statistical significance)

Limitations

Sample size not reported in the abstract.
Exposure duration not reported in the abstract.
Only two maintained temperatures (23.5°C and 25.5°C) within the transition region were tested during increasing intensities.
Findings noted as contrasting with other studies using a different measurement method (laser Raman spectroscopy), but details of those studies are not provided.

View raw extracted JSON

{
    "study_type": "in_vitro",
    "exposure": {
        "band": "RF",
        "source": null,
        "frequency_mhz": 1000,
        "sar_wkg": null,
        "duration": null
    },
    "population": "Multilamellar dimyristoylphosphatidylcholine (DMPC) vesicles (with DPH fluorescence probe)",
    "sample_size": null,
    "outcomes": [
        "Phase transition temperature/shift in multilamellar DMPC vesicles",
        "Microviscosity vs temperature (fluorescence depolarization using diphenylhexatriene, DPH)",
        "Differences between exposed and control samples (statistical significance)"
    ],
    "main_findings": "No shift of the phase transition was found during continuous-wave 1.0-GHz microwave exposure at specific absorption rates between 1 and 30 W/kg. No statistically significant differences were observed between exposed and control samples when temperature was maintained at 23.5°C or 25.5°C.",
    "effect_direction": "no_effect",
    "limitations": [
        "Sample size not reported in the abstract.",
        "Exposure duration not reported in the abstract.",
        "Only two maintained temperatures (23.5°C and 25.5°C) within the transition region were tested during increasing intensities.",
        "Findings noted as contrasting with other studies using a different measurement method (laser Raman spectroscopy), but details of those studies are not provided."
    ],
    "evidence_strength": "low",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "microwave radiation",
        "1.0 GHz",
        "RF exposure",
        "specific absorption rate",
        "SAR",
        "DMPC",
        "multilamellar vesicles",
        "phospholipid phase transition",
        "fluorescence depolarization",
        "diphenylhexatriene",
        "microviscosity",
        "TEM cell"
    ],
    "suggested_hubs": []
}

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AI-extracted fields are generated from the abstract/metadata and may be incomplete or incorrect. This content is for informational purposes only and is not medical advice.

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