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Behaviour of magnetic micro-particles in the human lung.
Radiat. Environ. Biophys. 32, 221-238 (1993)
Magnetic micro-particles were used to investigate the defence system of the human lungs against foreign material. After primary magnetisation a remanent magnetic field (RMF) of the lung can be measured that allows estimation of the amount of dust retained in the lung. After calibration of the system with a lung phantom the magnetic contamination retained in the lungs of dental technicians and welders was estimated at mean values of 22 and 500 mg respectively. In normal controls only 0.3 mg was found. About 0.5 mg of spherical monodisperse magnetite particles was deposited in the alveolar region of the lung by voluntary inhalation. The decay of the RMF, called relaxation, results from a misalignment of the dipole particles due to the activity of pulmonary macrophages. This macrophage activity is characterised by a cellular energy E. With a secondry magnetisation the lung can be remagnetised by rotation of the dipole particles. This allows an estimation of the intracellular viscoelasticity and the motility of the alveolar macrophages in vivo. Secondary magnetisation and relaxation curves of spherical monodisperse magnetite particles are presented. Intracellular viscosity was estimated to be η ≃ 100 Pa s at shear rates near 0.01 s-1, the rigidity modulus being v ≃ 4-8 Pa. Macrophage activity was described by a cellular energy E(z) ~ 5 · 10-18 J. Additionally, non-magnetic aerosol exposure resulted in a faster relaxation, which was interpreted to be due to activation of the macrophages. The magnetic particles were cleared with a half-time of ≃ 110 days.
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Publication type
Article: Journal article
Document type
Scientific Article
Language
english
Publication Year
1993
HGF-reported in Year
0
ISSN (print) / ISBN
0301-634X
e-ISSN
1432-2099
Quellenangaben
Volume: 32,
Issue: 3,
Pages: 221-238
Publisher
Springer
Reviewing status
Peer reviewed
Institute(s)
Abteilung Biophysikalische Strahlenforschung
Scopus ID
0027490661
Erfassungsdatum
1993-12-31