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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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        Publikationstyp
        Artikel: Journalartikel
    
 
    
        Dokumenttyp
        Wissenschaftlicher Artikel
    
 
     
    
     
     
    
    
        Sprache
        englisch
    
 
    
        Veröffentlichungsjahr
        1993
    
 
     
    
        HGF-Berichtsjahr
        0
    
 
    
    
        ISSN (print) / ISBN
        0301-634X
    
 
    
        e-ISSN
        1432-2099
    
 
     
     
     
	     
	 
	 
    
        Zeitschrift
        Radiation and Environmental Biophysics
    
 
		
    
        Quellenangaben
        
	    Band: 32,  
	    Heft: 3,  
	    Seiten: 221-238 
	    
	    
	
    
 
  
         
        
            Verlag
            Springer
        
 
         
	
         
         
         
         
         
	
         
         
         
    
         
         
         
         
         
         
         
    
        Begutachtungsstatus
        Peer reviewed
    
 
    
        Institut(e)
        Abteilung Biophysikalische Strahlenforschung
    
 
     
     
     
     
     	
    
    
        Scopus ID
        0027490661
    
    
        Erfassungsdatum
        1993-12-31