弹性因素在囊性纤维化患者痰液的粘弹性特性中占主导地位。

Elastic contributions dominate the viscoelastic properties of sputum from cystic fibrosis patients.

作者信息

Nielsen Heidi, Hvidt Søren, Sheils Catherine A, Janmey Paul A

机构信息

Department of Chemistry, Roskilde University, DK-4000 Roskilde, Denmark.

出版信息

Biophys Chem. 2004 Dec 20;112(2-3):193-200. doi: 10.1016/j.bpc.2004.07.019.

DOI:10.1016/j.bpc.2004.07.019

PMID:15572248

Abstract

Sputum samples from cystic fibrosis (CF) patients were investigated by oscillatory, creep and steady shear rheological techniques over a range of time scales from 10(-3) to 10(6) s. The viscoelastic changes obtained by mixing sputa with the actin-filament-severing protein gelsolin and with the thiol-reducing agent dithiothreitol (DTT) were also investigated. At small strains sputum behaves like a viscoelastic solid rather than a liquid. A nearly constant steady shear viscosity at low shear rates is only observed after long shearing times which cause irreversible changes in the samples. Creep-recovery tests confirm that sputa exhibit viscoelastic properties, with a significant elastic recovery. The results suggest that measurements of elastic moduli, rather than viscosities are more closely related to the mechanical properties of sputum in situ. Severing of actin filaments lowers the elastic modulus by 30-40%, but maintains viscoelastic integrity, while reduction of thiols in the glycoproteins nearly completely fluidizes the samples.

摘要

采用振荡、蠕变和稳态剪切流变技术，在从(10^{-3})到(10^{6})秒的一系列时间尺度上，对囊性纤维化（CF）患者的痰液样本进行了研究。还研究了通过将痰液与肌动蛋白丝切断蛋白凝溶胶蛋白以及与硫醇还原剂二硫苏糖醇（DTT）混合而获得的粘弹性变化。在小应变下，痰液表现得像粘弹性固体而非液体。仅在长时间剪切后才观察到低剪切速率下几乎恒定的稳态剪切粘度，这会导致样品发生不可逆变化。蠕变恢复试验证实痰液具有粘弹性特性，具有显著的弹性恢复。结果表明，弹性模量的测量而非粘度的测量与原位痰液的力学性能更密切相关。肌动蛋白丝的切断使弹性模量降低了30 - 40%，但保持了粘弹性完整性，而糖蛋白中硫醇的还原几乎使样品完全流化。