Shigeto Osako

Effects of Kanamycin on the Auditory Evoked Responses During Postnatal Development of the Hearing of the Rat

The ototoxic effects of kanamycin were studied in rats during the early postnatal period and at an adult age. Brain stem potentials as well as auditory cortical potentials were used for the estimating of ototoxic damage. The auditory potentials decreased promptly and markedly in the animals which were treated daily with 400 mg/kg body weight of kanamycin starting from the 11th day after birth. In these animals, the auditory potentials were almost completely abolished within 10 days after the beginning of the kanamycin treatment. However, when the same amount of kanamycin was applied earlier or later than that, i.e., avoiding the period of the initial appearance and the greatest development of auditory functions (from the 11th to the 15th day after birth in the rat), the auditory potentials were not apparently damaged. In light and scanning electronmicroscopy, marked ototoxic changes were observed which underlay the functional damage. The meaning of these findings is discussed.

Ciliary activity on adenoids of patients with otitis media with effusion

Ciliary activity of the adenoidal surface in patients with otitis media with effusion (OME) was evaluated by a photoelectric method. Three groups of patients were compared: a non-OME group whose members had experienced no episode of OME; a middle ear effusion (MEE)-negative OME group whose members had an episode of recurrent OME but no MEE during the month preceding the operation; and an MEE-positive OME group whose members were experiencing an episode of recurrent OME with MEEs when tissue was taken for examination. To serve as a comparison, the ciliary activity in the central pharynx of normal guinea pigs was evaluated using the same technique. The ciliary activity in all patients was significantly lower than that in normal guinea pigs. No significant difference in ciliary activity was apparent between the non-OME group and the MEE-negative OME group. However, both were significantly higher than the ciliary activity of the MEE-positive OME patients. The following findings are drawn from our data: ciliary activity on the surface of hypertrophic adenoids is depressed, and patients with OME have reduced ciliary activity compared with those who have no otitis media or those who have otitis media without effusion.

Temporary threshold shifts produced by exposure to vibration, noise, and vibration-plus-noise.

Changes in auditory sensitivity were recorded with a Bekesy audiometer technique following exposure to vibration in each of 300 cpm (5 Hz) and 1000 cpm (16.7 Hz), to broad-band noise of 82 dB SL and to both. Vibration at a frequency of 300 cpm and an amplitude of 6 mm, or at a frequency of 1000 cpm and an amplitude of 3 mm, were applied until the subject could no longer tolerate them (a 20 min period) by a noise-controlled vibration exciter. There was no significant change in threshold sensitivity after exposure to vibration alone. Exposure to vibration and noise simultaneously caused greater threshold shifts (TTS) and longer recovery time than exposure to noise alone. This was especially true with 1000 cpm vibration. It was suggested that the effects of the combined noise and vibration might be the results of some disturbances of physiological homeostasis or possible mechanical interactions with its blood supply.ZUSAMMENFASSUNGVeranderungen der Horfahigkeit wurden bei Schwingungen cpm bzw. 1000 cpm oder ...

IgG subclass deficiency in patients with upper respiratory tract infection.

Immunodeficiency syndromes are considered to be responsible for some intractable infections of the ear, nose or throat.In Japan, however, there have been only a few reports of IgG subclass deficiency.This is a report of four cases of chronic or recurrent respiratory infection considered to be related to low serum levels of IgG subclass.In two patients with purulent rhinorrhea and productive cough the diagnosis was chronic sinusitis, bronchiectasis and OME. Haemophilus influenza was isolated in sputum cultures. One patient had selective IgG2 deficiency and the other patient had a low serum IgG4.The third patient had prolonged otitis media, had low serum IgG3 and a diagnosis of Prader-Willi syndrome, the fourth had recurrent otitis media, low serum IgG4 and a diagnosis of Wiskott-Aldrich syndrome.Monthly intravenous injections of human immunoglobulin with high concentrations of the deficient subclass and appropriate antibiotic therapy brought about cures of their infections.

Acoustic Influence of the Aminoglycoside Antibiotics

We analyzed the development of auditory disorders in fetuses and infants.The naturally delivered newborn rats that had ingested antibiotics through their mothors were studied to determine Preyers auricle reflex and the auditory vertex evoked potential. (AEP).Dosages of 400mg/kg and 200mg/kg of Kanamycin, 200mg/kg of Dideoxykanamycin B and 150mg/kg of Gentamicin were administered to the newborn for 7 to 10 consecutive days during five different periods between 24 hours and 40 days after their birth. The animals were anesthetized with Nembutal 30mg/kg given intraperitoneally.We first checked the development of hearing in the normal newborn. Their evoked potential was obtained 11 or 12 days after birth and by 16 to 20 days after birth, the value of the potential was about the same as adult rats.The value of auditory vertex evoked potential of newborn to which the antibiotics had been administered was then determined. During the embryonic period and newborn period of 1 to 7 days, little or no effect of the antibiotics was observed. On the other hand, administration of doses at 10 to 14 days after birth produced serious side effects. Such adverse effects were not apparent in the samples from rats given the drugs after the 16th day of birth.Our results indicate that the aminoglycoside antibiotics have a serious effect on the hearing of the rats around 10 to 14 days after birth.

Distribution of Aminoglycoside Antibiotics in Hearing Organ of Embryo and Infant Animals

It is suspected that one of the causes of congenital auditory disorders is a certain type of drug administered to a pregnant mother which hinders the development of auditory organ of the fetus. We selected 3 types of aminoglycoside antibiotics for the experimentation, namely, Kanamycin, Dideoxykanamycin B and Gentamicin to determine the influence of these drugs on rats and mice in their embryonic and infant stages.First, the above drugs were given subcutaneously to pregnant animals and infant animals, and by means of bioassay method, all three antibiotics were traced in the internal ears and other organs of the fetuses and infant animals. The transitional density of aminoglycoside antibiotics in the internal ear of mice and rats was considerably high.Next, we examined the naturally delivered newborn rats and mice to determine the Preyers auricle reflex.It is our deduction that the period when the adverse effects of such antibiotics on hearing organs of the fetuses and the newborn appear most conspicuously is 10 to 14 days after birth.