Fitzgerald J E, Green G G, Birchall J P, Pearson J P
Department of Physiological Sciences, University of Newcastle upon Tyne; UK.
Biomed Pharmacother. 1988;42(8):505-11.
Middle ear effusion was obtained from children with otitis media with effusion and separated into thick (mucoid) and thin (serous) pools. Both effusion types contained similar amounts of non-dialysable solids. However, the thick effusions contained more mucus glycoprotein than the thin effusions, 25% and 8.2% respectively. Amino acid and carbohydrate analysis of the CsCl purified mucus glycoproteins demonstrated that the glycoprotein from the thick and thin effusions differed in their protein core, those from the thick effusions possessing a higher percentage of serine and threonine, the amino acids to which the sugar side-chains attach. They are also more glycosylated. N-acetyl cysteine and mercaptoethanol caused a fall in the viscosity of solutions of purified middle ear glycoprotein and effusion homogenate. However, longer term incubation caused a rise above the starting viscosity. This effect was concentration-dependent, and was mediated by low molecular weight components in the effusion and not the mucus glycoprotein. S-carboxymethyl cysteine had no effect on the viscosity of either the purified mucus glycoprotein or the effusion homogenate. Therefore, to produce a decrease in effusion viscosity in vivo, the concentration of mucolytic reaching the middle ear and the time it remains there are critical factors.
从患有渗出性中耳炎的儿童中获取中耳积液，并将其分离为浓稠（黏液样）和稀薄（浆液性）积液池。两种积液类型所含的非透析性固体量相似。然而，浓稠积液所含的黏液糖蛋白比稀薄积液多，分别为25%和8.2%。对经氯化铯纯化的黏液糖蛋白进行氨基酸和碳水化合物分析表明，浓稠和稀薄积液中的糖蛋白在蛋白质核心方面存在差异，浓稠积液中的糖蛋白丝氨酸和苏氨酸百分比更高，而糖侧链附着于这些氨基酸上。它们的糖基化程度也更高。N-乙酰半胱氨酸和巯基乙醇导致纯化的中耳糖蛋白溶液和积液匀浆的粘度下降。然而，长期孵育会导致粘度升至起始粘度以上。这种效应具有浓度依赖性，并且是由积液中的低分子量成分而非黏液糖蛋白介导的。S-羧甲基半胱氨酸对纯化的黏液糖蛋白或积液匀浆的粘度均无影响。因此，要在体内降低积液粘度，到达中耳的黏液溶解剂浓度及其在中耳停留的时间是关键因素。
