Yoshihiro Ohashi

Mucociliary Disease of the Middle Ear during Experimental Otitis Media with Effusion Induced by Bacterial Endotoxin

Lipopolysaccharide (10 μg/mL) derived from Klebsiella pneumoniae was injected into the middle ear of guinea pigs. The animals were killed painlessly on days 1, 3, and 7 after inoculation, and the mucosal samples from two sites within the tympanic cavity, close to the tympanic orifice and distal to the orifice, were examined for ciliary activity and epithelial morphology. At day 1 and day 3 serous effusion was observed and deterioration of ciliary activity and morphologic changes were observed. No effusion was recognized at day 7, when the ciliary activity in the distal mucosa was still diminished and that in the proximal mucosa had recovered to a normal level. Our data have shown that lipopolysaccharide extracted from K pneumoniae can produce otitis media with effusion in laboratory animals, and dysfunction of cilia due to lipopolysaccharide probably is responsible for the accumulation of middle ear effusion. The mucociliary system is indeed an important defense system and failure of such a system, especially in the mucosa close to the tympanic orifice, can cause the buildup of effusions.

Influenza a Virus-induced Otitis Media and Mucociliary Dysfunction in the Guinea Pig

There is much epidemiologic, clinical and laboratory evidence that viral infection is involved in otitis media with effusion (OME). However, few studies have demonstrated any direct influence of viruses on the tubotympanum. The purpose of this study was to establish the effect of influenza A virus having invaded the tubotympanum and so elucidate the possible mechanism by which this virus contributes to the pathogenesis of OME. Eighty guinea pigs with normal otoscopic findings were inoculated with 0.2 ml suspension of influenza A (3.3 x 10(8) PFU/ml) into the tympanic cavity through the tympanic membrane. To serve as controls, the same number of guinea pigs were injected with 0.2 ml of physiologic saline solution into the tympanic cavity. At 3, 7, 14, and 28 days postinoculation, they were used for examination of the mucociliary function. Middle ear effusions as well as mucociliary dysfunction were observed only in the animals inoculated with the virus. The ciliary activity in the bulla was declined at any time examined. On the other hand, the ciliary activity in the Eustachian tube and the tympanic orifice was slightly lowered between 7 and 14 days, but the level was not different from that of the controls. However, the number of active ciliated cells (showing more than 500 beats/min) was significantly smaller than that of the controls. The mucociliary clearance time of the tubotympanum was more prolonged than that of the controls at 3, 7, and 14 days, and returned to the control level at 28 days. A variety of morphological changes were observed in the tubotympanum treated with the virus. Major pathologies observed included general inflammatory cell infiltration, vacuolation and other degeneration of ciliated cells, and vascular damage and increased vascular permeability. Regeneration of cilia or ciliated cells followed the degeneration, which included an increased number of basal cells and newly formed centrioles. However, the viral infection also affected the epithelial cells with new centrioles. Our study demonstrates that viral infection can evoke mucociliary dysfunction of the tubotympanum and create increased susceptibility to bacteria. Therefore, viral infection may enhance bacterial infectious processes in the tubotympanu thereby contributing to the occurrence of OME.

Acute effects of sulfur dioxide exposure on the middle ear mucosa

A variety of atmospheric pollutants are known to depress mucociliary function in the respiratory system. Since the mucociliary function in the middle ear is similar, and the middle ear may be invaded by atmospheric pollutants, we decided to investigate the possible contribution of sulfur dioxide to middle ear effusion. Guinea pigs were exposed for 24 hours to 300 ppm of sulfur dioxide or air. Immediately after exposure, ciliary activity and epithelial structure were examined close to the tympanic orifice (proximal site) and more distal to it (distal site). In the animals exposed to sulfur dioxide, no effusion was found in the tympanic cavity. Ciliary activity was reduced only in the distal site. Electron microscopy demonstrated hypersecretion in the proximal site and severe pathologic changes in the distal site. Although the normally functioning cilia in the proximal site may prevent retention of surplus secretions in the ear, sulfur dioxide may promote middle ear effusion when combined with other detrimental factors, because it stimulates mucus secretion in the proximal site and impairs ciliary function in the distal site.

Histamine-induced Mucociliary Dysfunction and Otitis Media with Effusion

Histamine, which has been found in middle ear effusions, is a potent pharmacological mediator released at an early stage of allergic reactions or general inflammatory process, increasing permeability of small blood vessels. Histamine might be involved in the origin and chronicity of middle ear effusions. In this study we studied the effect of histamine on the mucociliary function. First we examined the effect of histamine and its H1 and H2 blockers on the ciliary activity in the middle ear. 10(-2) M of histamine deteriorated ciliary activity; however, at lower concentrations ciliostimulatory effects were demonstrated for histamine (between 10(-8) M and 10(-4) M). Such ciliostimulatory effects were not affected by diphenhydramine (H1-blocker) but were reduced by cimetidine (H2-blocker). Thus histamine stimulates ciliary activity by combining with H2-receptor. Intratympanic injection of 10(-4) M of histamine induced accumulation of middle ear effusions (MEEs). The volume of MEEs was largest at 1 day postinjection when its mucociliary clearance time was longest. Then the mucociliary clearance time became shorter, but it was still significantly longer than that of the control animal. Ciliary activity in the tubotympanum showed no recovery through the observation period. On the other hand, intratympanic injection of 10(-6) M of histamine produced MEEs at 1 and 3 days postinjection when the mucociliary clearance time was longer than that of the control group. At 8 days, when most ears did not demonstrate MEEs, the mucociliary clearance time and ciliary activity in the Eustachian tube and tympanic orifice reached the level of the control group. Our present study demonstrates that histamine can induce mucociliary dysfunction of the tubotympanum resulting in middle ear effusions, and that cilia, especially those present in the tube and the tympanic orifice, have a significant role in eliminating middle ear effusions.

Increased ciliary beating frequency of nasal mucosa following immunotherapy for allergy.

The present study was designed to elucidate the effect of immunotherapy on the beating frequency of nasal cilia in patients with nasal allergy. Of 40 patients with nasal allergy due to Dermatophagoides farinae, 20 were treated with immunotherapy by the use of D farinae extracts, and 20 control patients were treated with antihistamine tablets. Mucosal pieces were taken from the right inferior turbinate before and 1 year after the initiation of treatment, and the ciliary beating frequency (CBF) was examined by a photoelectric method. The use of antihistamine tablets did not increase CBF even when it relieved the nasal symptoms. Immunotherapy, on the other hand, increased CBF in 66.7% of patients when it alleviated their nasal symptoms. The CBF before immunotherapy of patients who showed an increased CBF after treatment was statistically higher than that of patients who did not.

Effect of Formalin-fixed Hemophilus Influenzae and Streptococcus Pneumoniae on Dye Transport by the Chinchilla Eustachian Tube

An in situ method for measuring the ability of the middle ear and eustachian tube ciliated epithelium to transport dye to the nasopharynx was used to assess the role endotoxin-containing killed bacteria have on the development of otitis media with effusion. In addition, electron microscopy was used to monitor histological changes induced by exposure to these organisms and the ability of the mucosa to recover. The results indicated that exposure to a killed gram-negative but not a gram-positive otitis media pathogen leads to early production of middle ear fluid, evidence of capillary leakage and significant slowing of mucociliary transport. The damage was, however, reversible with the epithelium returning to normal both functionally and histologically within 7 days of exposure.

STRUCTURAL ORGANIZATION OF THE MAMMALIAN AUDITORY HAIR CELLS IN RELATION TO MICROMECHANICS

The mammalian auditory sensory cells are mechano-receptors characterized by sensory stereocilia, the cuticular plate, and the polarized cell body, innervated by the afferent and efferent nerve endings. The auditory sensory cells in mammals are further specialized into two functional groups (inner hair cells vs. outer hair cells) that are morphologically distinct from each other with differing innervation patterns. There is good evidence to suggest that the inner hair cells are largely responsible for auditory sensitivity and the outer hair cells are responsible for auditory tuning (Liberman & Kiang, 1984). The role of the outer hair cell in frequency selectivity is thought to be the result of its interaction with the inner hair cell. Recent evidence suggests that the outer hair cell of the cochlea is motile. It has been suggested that this outer hair cell motility is responsible for generating the otoacoustic emission and tuning of the auditory sensory response by exerting influence on the micromechanical environment of the inner hair cell stereociliary bundles. Thus, motile activity of the outer hair cell may have a direct bearing on the micromechanics of the cochlea. This paper is an attempt to review the current data of the sub-structural organization of the mammalian auditory hair cell that are relevant to the sensory transduction process and cell motility.

An experimental study of mucociliary pathology of the eustachian tube in otitis media with effusion induced by irradiation

SummaryWe have examined the function and fine structure of the mucociliary system of the eustachian tube in an experimental study of otitis media with effusion induced by X-ray irradiation. Functional examination demonstrated that the ciliary activity was diminished in such a condition, while morphological observations showed pathological findings including compound cilia, vacuolation of ciliated cells and expansion of intercellular space. These findings show that irradiation-induced otitis media with effusion results in impairment of the mucociliary system. As evidenced by these studies, the mucociliary system in the eustachian tube has an important role in the clearance of fluid produced in the tympanic cavity as well as affording improvement in this disease.

Ciliary Activity in the Tubotympanum during Type I Allergic Reaction

The immune system is active in the tubotympanum and some middle ear diseases might be partially or exclusively immunologically mediated. However, the effect of an allergic reaction on the tubotympanic cilia remains to be elucidated. The response of normal tubotympanic cilia from the guinea pig was investigated in an in vitro experimental system to evaluate ciliary responsiveness without the influence of secretions. Mucosal samples were obtained from three different tubotympanic locations (Eustachian tube, and middle ear close to the tube (proximal site) and more distal to the tube (distal site)). Each mucosal sample was cultured in 2 ml of RPMI 1640 and 1 ml of heparinized venous blood from a nonallergic human subject, a patient with ragweed-sensitive nasal allergy, or 3 patients with Dermatophagoides farinae-sensitive nasal allergy. One microgram of D. farinae extracts was added in each chamber to evoke an in vitro allergic reaction, and the ciliary activity of the most active cell in each culture was monitored for up to 120 min. When D. farinae extracts were added into the chamber containing blood from subjects without sensitivity to D. farinae, no changes were induced in ciliary activity throughout the examination. When the same dose of allergens was added into the chamber containing blood from D. farinae-sensitive subjects, ciliary excitation was induced in the culture from the Eustachian tube and the proximal site. The peak and plateau of this phenomenon were observed at 30-40 min after the addition of the allergen, and a gradual slowdown to the baseline level was observed after the plateau. No ciliary depression was induced by an allergic reaction in the culture from the Eustachian tube or the proximal site. Such ciliostimulatory effects were correlated with D. farinae induced-percent histamine release from whole blood. In the cultures from the distal site, however, a gradual ciliodepression followed the peak of ciliary excitation. In conclusion, an in vitro allergic reaction affected the ciliary activity in the distal site, but such ciliary dysfunction was not observed in the Eustachian tube or the proximal site during such a reaction.