Relationship between dynamic viscoelasticity and biochemical parameters in whole sputum from patients with...

To obtain suitable biochemical parameters for measuring the dynamic viscoelasticity of sputum, we examined the relationships of the dynamic viscoelasticity with the dry weight (DW) and the contents of fucose, a parameter of airway mucous glycoprotein (AMG), and total protein (TP) and major proteins in whole sputum. The DW and TP, albumin and IgG concentrations and elastase activity were higher in purulent sputum than in mucoid-mucopurulent sputum, but there was no significant difference in the concentrations of airway wall-derived substances, such as fucose and S-IgA in the two. In mucoid-mucopurulent sputum, the dynamic viscosity (eta') and elastic modulus (G'), an indicator of dynamic elasticity, were most closely correlated with the fucose concentration (r = +0.75, and +0.74, p < 0.005 at 1 Hz) and slightly correlated with the DW, TP and S-IgA, but not with the other parameters tested. In the purulent sputum, the eta' and G' correlated with the DW and concentration of TP (r = +0.70-0.80, p < 0.005), but not with any concentrations of fucose, S-IgA or albumin. The results indicate that as parameters for estimating the dynamic viscosity and elasticity of whole sputum, fucose is useful for mucoid-mucopurulent sputum whereas DW and TP are useful for purulent sputum.