[Biochemical differences in middle ear effusions between pediatric and adult patients, (I). The lipid composition]

Middle ear effusions (MEEs) from adult were usually serous in nature, but those from child were mucous. MEEs contain the substances secreted by the epithelial cells of the middle ear and Eustachian tube to regulate surface tensions as well as those produced as the result of inflammation, but the biochemical bases of serous and mucous MEEs have not been clearly established. To clarify the biochemical differences giving rise to the characteristic physicochemical properties of MEE from children and from adults, all lipid components of MEEs from 7 children and 7 adults by thin-layer and gas liquid chromatographies were analyzed, and also they were compared with those from sera. Although no significant difference in lipid composition was observed between adult and pediatric sera, the amounts of phosphatidyl ethanolamine (PE) and phosphatidyl serine (PS) in pediatric MEE were higher than those in adult MEE. The relative concentration of PE in the total phospholipids of pediatric MEE was 26.5%, significantly higher than that in adult MEE (9.2%), and pediatric (6.1%) and adult (3.1%) sera. A similar high concentration of PS was also observed in pediatric MEE. Since phospholipids were the major components of surfactants secreted from the epithelial cells of the middle ear, significantly high concentrations of the charged phospholipids, PE and PS, might be responsible in part for the characteristics of pediatric MEE. To compare physical properties in different phospholipid compositions between pediatric and adult MEEs, polarization value was measured with liposomes in each phospholipid compositions. The polarization value in pediatric phospholipid composition liposomes was higher than in adult. It seemed that the microviscosity in pediatric MEE was lower than in adult.