Surface active substances in the chinchilla tubotympanum. A biochemical study

Ultrastructural and ultracytochemical study of the middle ear epithelium in the chicken, Gallus gallus domesticus

The fine structure of the epithelium lining the tympanic cavity of the chicken was studied by TEM and SEM. In addition, the distribution of nonspecific esterase activity in the epithelium was investigated by TEM. Ultrastructural study revealed the presence of disk-like apical protrusions of the epithelial cells, previously not observed in other cell types. The protrusions contained some cytoplasmic organelles and were characterized by a ring-shaped thickening around their periphery. The ring was made up of a granulo-filamentous material. Our observations clearly indicate the existence of an apocrine secretory mechanism, consisting of a progressive detachment of disk-like protrusions from the apex of the epithelial cells. The ultracytochemical study demonstrated nonspecific esterase activity on the epithelial surface and in the secretory vesicles. We propose that nonspecific esterase is a marker for middle ear surfactant in birds.

Surfactant in the middle ear and eustachian tube: a review

There has been a recent surge in research on surfactant and surfactant proteins. Fields ranging from immunology to surface chemistry are making contributions to our understanding of this multifunctional compound. This paper reviews the literature on the structure and function of Eustachian tube surfactant. It covers the proposed functions of endogenous surfactant in normal physiology, as well as the experimental applications of exogenous surfactant in the treatment of otitis media. The analysis is based on four platforms of research: the role of surfactant in the innate immune system, the effect of surfactant on surface tension and Eustachian tube opening pressure, the capacity of surfactant to alter the rheological properties of mucus and the efficiency of the mucociliary system, and the ability of surfactant to mitigate oxygen free radical damage.

Nebulized Surfactant for Experimentally Induced Otitis Media with Effusion

Eustachian tube dysfunction frequently results in clinical evidence of otitis media with effusion (OME). Surface active substances, surfactants, are hypothesized to play a role in normal eustachian tube function. Recent work in a rodent model has demonstrated improved eustachian tube function with topical application of surfactants to the middle ear. A novel, noninvasive, and clinically practical method of delivering surfactant to the eustachian tube was studied in a gerbil model of OME. Otitis media with effusion was experimentally induced in 20 gerbils by transtympanic inoculation of heat-killed Streptococcus pneumoniae. This represents a well established model for creating a serous effusion in the gerbil that significantly increases eustachian tube opening pressure. Effusion developed in 27 of 40 ears (67.5%) after inoculation. An inhaled nebulized surfactant was used to treat the animals with microscopically confirmed OME in one or both ears. The treatment period was 5 days. Eustachian tube opening studies were performed on both affected and nonaffected animals. Successful eustachian tube opening pressures were obtained in 30 of 36 ears (83.3%). The mean opening pressure for ears without effusion (healthy ears) was 42.8 mmHg. The mean opening pressure for ears with effusion in animals treated with nebulized surfactant was 41.4 mmHg. The difference between these mean values was not statistically significant ( t = 0.32; p > 0.50). This pilot study suggests that inhaled nebulized surfactant may be efficacious in treating eustachian tube dysfunction when manifested in disorders such as OME.