Kazutomo Kawamoto

Ultrastructural changes of the nerve elements following disruption of the organ of Corti. II. Nerve elements outside the organ of Corti.

Various stages of changes in the nerve fibers, spiral ganglion cells, and satellite cells from the guinea pig cochlea 3 to 137 days after perilymphatic perfusion with streptomycin solution (2 and 20%) were observed electron microscopically. Initially, the axoplasms of the cochlear nerve fibers became swollen or pyknotic. Then, the axons disappeared and myelin lamellae disrupted. The Schwann cells shrank and degenerated, though their basement membranes survived for a time. Regeneration of the cochlear nerve fibers began with extension of axonal sprouts into the tube of the basement membrane and surviving Schwann cells, which still contained myelin debris. Only one of the axonal sprouts matured for myelination. These regenerating cochlear nerve fibers were found in the osseous spiral lamina, modiolus and internal auditory meatus, but these fibers atrophied and disappeared afterward. Retrograde degeneration occurred in the olivo-cochlear bundle. Some of the efferent myelinated fibers also showed temporary regeneration.

Mucociliary dysfunction in experimental otitis media with effusion

To investigate the morphologic changes of the eustachian tube mucociliary transport systems, experimental otitis media with effusion was induced by immune complex injection into the bullae of experimental animals. Horseradish peroxidase was chosen as an antigen because of its high antigenicity and traceability under light and electron microscopy. Seventy-three guinea pigs and 41 chinchillas were divided into three groups: active Arthus group, passive Arthus group, and control group. Animals were killed under general anesthesia from the first to 30th day after the injection. Within 5 days after injection, effusions were observed consistently in all animals, but in only 80 per cent on the 7th day and in only 50 per cent after the 10th day after injection. The most conspicuous findings were that the interciliary space of the mucociliary system was diffusely occupied by an electron-dense mucus, and the upper part of the ciliary shafts were tightly glued together. These features seem to indicate rheologic alterations of the mucus and a disorder of its coupling to the cilia. This study strongly suggests that the mucociliary coupling disorder caused by altered rheologic properties of the mucus causes clearance dysfunction of the eustachian tube, resulting in middle ear effusion. The various inflammatory products contained in the middle ear effusions elicit a persistent vicious cycle of inflammatory reactions in the tubotympanum.

Gas Analysis of the Middle Ear Cavity in Normal and Pathological Conditions

The gas of the tympanic bulla was measured using 18 normal and 14 tube-obstructed guinea pigs. The concentrations of CO2 and O2 were 4.8 +/- 1.0% and 7.2 +/- 1.8% in normal animals, and 4.3 +/- 1.6% and 8.1 +/- 2.0% in tube-obstructed animals, respectively. The bulla was opened to room air and then closed again. The recovery process of each gas was examined. In normal animals, CO2 and O2 were exponentially changed toward the pre-open value with time. The time constants of this recovery process were 15 min and 97 min in CO2 and O2, respectively. In tube-obstructed animals, however, this quick recovery of CO2 was significantly delayed (time constant, 50 to 80 min), although there was no effect upon the recovery of O2. This delayed recovery of CO2 is likely to be due to the edema of the mucous membrane.

Ultrasonic electrocochleography in guinea pig.

In order to obtain information about how ultrasonic stimuli are perceived (USP) in man, guinea pig cochleae were stimulated by bone conduction with frequencies (98.8 and 143.5 kHz) above the normal auditory field of this animal. The cochlear potentials recorded consisted of CM, SP and AP originating from the basal turn of the cochlea, and were found to be influenced by asphyxia, administration of ethacrynic acid, hypothermia and change of interstimulus interval. In addition, in kanamycin-treated animals the mean AP amplitude decreased to about one fourth of the normal value, and the mean AP latency increased significantly. These findings suggest that there is no special sense organ for the detection of USP but that such sounds activate hair cells in the basal turn of the cochlea.

Prognosis and Endotoxin Contents in Middle Ear Effusions in Cases After Acute Otitis Media

We analysed the endotoxin content of middle ear effusion (MEE) from patients after acute otitis media, by a Limulus assay. Endotoxin was positive in 70% of the cases treated with antibiotics at an acute event for more than 5 days, while the incidence of bacteria was only 22%. One month after the sample collection, cases with a high concentration of endotoxin in MEE still tended to have effusion. These results suggest that endotoxin in MEE cannot be easily inactivated and may be involved in the development of acute otitis media into chronic otitis media with effusions.

Some Surface Views of the Stria Vascularis and its Adjacent Areas

The surface views of the stria vascularis and its adjacent areas are presented after a silver reaction, a glutamic dehydrogenase staining and a H-3-uridine autoradiography. Between the stria vascularis and the spiral prominence, as well as Reissners membrane, some rows of spindle-formed cells were observed on the endolymphatic surface running parallel to the stria vascularis from the base to the apex of the cochlea. The H-3-uridine autoradiography of the endolymph administration revealed distinct labels of the stria vascularis and the spiral prominence. From these results, the resorptive function of the stria vascularis and the spiral prominence is discussed.

Reissner's membrane, its light microscopic structures and permeability problems in literature.

ZusammenfassungEs wurden Photogramme der präparierten Reissnerschen Membran beim Meerschweinchen, Hund, Kaninchen und bei der Katze mit Anmerkungen über einige charakterische Eigentümlichkeiten vorgelegt. Zugleich wurde ein historischer Überblick über die Permeabilitätsprobleme dieser Membran gegeben.SummaryLight microscopic structures of Reissners membrane in a guinea pig, a rabbit, a cat and a dog were shown commenting on their several characteristic features. And. permeability problems of this membrane were historically reviewed.

A Case-Control Study of Nasal Cancers: An Occupational Survey

A case-control study on the possible association between nasal cancers (NC) and occupations was undertaken for 107 male patients with nasal or paranasal cancer and 413 patients with other otorhinolaryngological disease (controls) admitted during the past 10 years to the Department of Otorhinolaryngology, Tohoku University Hospital. The controls were matched by sex, age, and time of admission. However, in the occupational groups surveyed, no evidence such as reported in England and other countries was obtained that could confirm the relationship between nasal/paranasal cancers and woodwork (especially furniture making). Although the relative risk of NC for farmers, foresters, carpenters and plasterers was found to be approximately 2, occupational exposure was hardly considered to be a likely cause. Instead, some common factors involved in the life style including dietary customs of people engaged in these occupations seemed to play a role in the increased relative risks.

Generation Mechanism of the Negative Endocochlear Potential during Early Stage of Anoxia

To investigate the generation mechanism of the -EP in anoxic cochlea, the perilymphatic space was perfused with solution of various K+ concentrations in 38 guinea pigs when the -EP was maximally reduced by anoxia. Although the perfusion of scala tympani and vestibuli with Ringer-Locke solution or that of scala vestibuli with 154 mM K+ solution did not have any effect upon the -EP, the potential was elevated to 0 mV when the scala tympani was perfused with 154 mM K+ solution. Furthermore, the elevation of the potential was less remarkable when the K+ concentration in perfusate was reduced. The level of the potential during perfusion was closely related to K+ concentration in perfusates. The present results strongly suggest that the -EP is the result of the K+ diffusion potential and this diffusion mechanism is performed through the organ of Corti.

N1 Latency Prolongation in the Guinea Pig Cochlea Treated with Nitrogen Mustard-N-Oxide Studied by Narrow Band Analysis

The effect of nitrogen mustard-N-oxide (NMO) upon the click and tone burst–evoked N1 latency was examined in 14 albino guinea pigs. In all animals except one, the pseudothresholds of action potentials were elevated, especially in the high tone area. In addition to the amplitude reduction, the N1 latency was prolonged in 12 animals. The narrow band analysis of N1 revealed that the latency was equally prolonged in all frequency areas, although the amount of the amplitude reduction was much larger in the high frequency area. It was concluded that the prolongation of the N1 latency in NMO-treated animals was due to dysfunction of outer hair cells along the entire cochlear partition.