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Biomedical subjects

I Ohtani

Publications and source records attributed to I Ohtani.

At least 55 records · Page 3Linked to original sources
PubMed1990

Potentiation of inner ear damage following electron beam irradiation with CDDP administration.

This study was designed to examine the combined ototoxic effects of cisplatin, an antitumor platinum compound, administration and electron beam irradiation on the inner ear of guinea pigs, histopathologically. One group received saline solution 4 ml/kg/day and the other group received cisplatin of 2 mg/4 ml/kg/day for five consecutive days. The right temporal bones of all animals of both groups were exposed to the electron beam of 14 Gy/day 3 hours after the daily injection of saline or cisplatin. All animals were sacrificed for inner ear histopathological findings 21 days after the last injection. A combination of cisplatin administration and electron beam irradiation produced a severe potentiation of the outer hair cell damage with no inner hair cell damage. Therefore, in treatment of head and neck carcinomas, it is important to pay attention to inner ear damage caused by combination therapy of cisplatin and electron beam irradiation which involves the inner ear.

Animals↗
PubMed1988

Intraoperative EEG monitoring: (I). Parametric representation of processed EEG during anesthesia.

One of the most common techniques of EEG monitoring during operations is to produce a three dimensional image by displaying the frequency distributions with respect to time as in compressed spectral array (CSA) and density-modulated spectral array (DSA). In order to characterize these images by numerical parameters, we defined two parameters; the percent spectral edge frequency as the frequency at which the one-sided-power sum reaches the designated percentage of the total; and the mean frequency as the power-weighted mean within the interval that includes a dominant spectrum in the frequency distribution. These parameters were superimposed on displays to characterize EEG changes, and they proved to be a very powerful tool to quantitate variations in data among anesthetic techniques and thus efficiently control the depth and duration of anesthesia. We report a number of actual cases.

Adult↗
PubMed1988

Intraoperative EEG monitoring: (II). Similarity analysis using density-modulated t array.

A method of showing the similarity, in other words, defining the difference between a pair of EEG patterns has been developed. By using the student t test on the power spectra at the appropriate frequency intervals, the t values obtained can be used as an indicator of the difference between the spectral patterns with respect to the frequency intervals. This so-called t-profile can be computed on real time basis and the result superimposed in different colors using the apparatus described previously to produce a 3-dimensional picture. We call this picture a density-modulated t array or DTA. Along with CSA and DSA (compressed/density-modulated spectral arrays), it proved to be a very powerful tool in intraoperative EEG monitoring.

Adult↗
PubMed1985

Protective effect of fosfomycin against aminoglycoside ototoxicity.

The protective effect of fosfomycin against aminoglycoside (dibekacin)-induced ototoxicity was studied in rats. Rats were injected with 100 or 50 mg/kg of dibekacin with or without 500 mg/kg of fosfomycin for 60 or 120 consecutive days. Inner ear damage appeared to be more reduced histopathologically in animals given both dibekacin and fosfomycin than in animals given dibekacin alone. Similarly, renal damage appeared to be reduced histopathologically and functionally by the combined administration of dibekacin and fosfomycin. The mechanism of reduced ototoxicity may be as follows: fosfomycin inhibits the accumulation of dibekacin in the kidney, and reduces its concentration in the kidney and serum. Consequently, the amounts of dibekacin reaching the inner ear are decreased, and ototoxicity is reduced.

Acetylglucosaminidase↗
PubMed1985

Low ototoxicity and its mechanism of netilmicin.

The ototoxicity and nephrotoxicity of netilmicin were compared with those of dibekacin, kanamycin and amikacin using rabbits. Groups of 5 rabbits each were given doses of 50 or 100 mg/kg of either one of the four drugs for 30 days, and 10 days after the last injection, all animals were prepared for histopathological studies. Results show the least ototoxicity of netilmicin in comparison to the other three antibiotics. It has been concluded that the low ototoxicity of netilmicin is due not to its lack of accumulation in the perilymph but to its low toxicity to the hair cells.

Amikacin↗
PubMed1985

Reduction of cisplatin ototoxicity by fosfomycin in animal model.

The protective effect of fosfomycin against cisplatin-induced ototoxicity was studied in rats. Sixty-four Fischer rats were injected intravenously with daily doses of 1, 2, 5, and 10 mg/kg of cisplatin with or without 300 mg/kg of fosfomycin for a varying period from 1 to 10 days. The total dose of 10 mg/kg of cisplatin was given equally in all animals. Inner ear damage appeared to be more reduced histopathologically in animals given both cisplatin and fosfomycin than in animals given cisplatin alone. Similarly, renal damage appeared to be reduced histopathologically and functionally by the combined administration of cisplatin and fosfomycin.

Animals↗
PubMed1985

Aural abnormalities in Klippel-Feil syndrome.

Klippel-Feil syndrome, the triad of short neck, low occipital hairline, and limitation of movement of the head, is often associated with other serious congenital anomalies of the nervous, urogenital, and cardiovascular, and respiratory systems. Hearing loss is the second most common associated anomaly following neurologic defects. Histologic studies of the temporal bones of an infant with Klippel-Feil syndrome whom we studied showed severe anomalies in one ear consisting of microtia, aural atresia, maldeveloped ossicles, fixed stapes, hypoplastic facial nerve, short cochlea, and large diameter of the lateral semicircular canal.

Abnormalities, Multiple↗
PubMed1984

Relationship between ototoxicity of aminoglycoside antibiotics and their transferability into inner ear fluids.

The purpose of this study is to clarify the question whether the difference of severity of ototoxicity induced by the aminoglycoside antibiotics depends on the difference of quantity of transferability into inner ear. Aminoglycoside antibiotics (tobramycin, kanamycin, netilmicin and ribostamycin) were injected for 30 consecutive days to rabbits. The relationship between the severity of hair cell damage and concentration of antibiotics in perilymph was investigated. The drug concentration in the perilymph was determined by the bioassay method, and using the surface preparation technique the hair cell damage was observed under a phase contrast microscope. It was concluded that the difference of severity of ototoxicity induced by the aminoglycoside antibiotics is due to the difference of their own toxicity to hair cells but not to the difference of their transferability into the perilymph.

Aminoglycosides↗
PubMed1984

Osteoma of the external auditory canal.

A case of osteoma of the external auditory canal in a 19-year-old male patient was reported. The differentiation between osteoma and exostosis was discussed clinically, histopathologically and scanning electron microscopically.

Adult↗
PubMed1984

Mechanism of protective effect of fosfomycin against aminoglycoside ototoxicity.

The purpose of this study was to clarify the mechanism of the protective effect of fosfomycin (FOM) against inner ear damage induced by an aminoglycoside dibekacin (DKB), when administered concurrently DKB and FOM. Rats were treated with 50 mg/kg of DKB with or without 500 mg/kg of FOM for short-term administration. No significant difference was seen in the serum peak level and in the area under the curve between the group receiving DKB alone and the combined administration group of DKB and FOM. On the other hand, the DKB level in the kidney was significantly lower in the combined administration group than in the group receiving DKB alone. The mechanism of protective effect of FOM against DKB-induced ototoxicity may be considered as follows: FOM inhibits the accumulation of DKB in the kidney and reduces its concentration in the kidney and serum. Consequently, the transferability of DKB into the inner ear is decreased, and finally inner ear damage is reduced.

Animals↗
PubMed1984

[Reduction of cisplatin toxicity by fosfomycin in animal models].

The protective effect of fosfomycin against cisplatin-induced toxicities was studied in rats. A total of 64 Fischer rats were injected intravenously with daily doses of 1, 2, 5 and 10 mg/kg of cisplatin with or without 300 mg/kg of fosfomycin for a period varying from 1 to 10 days. The same total dose of 10 mg/kg of cisplatin was given to all animals. Cisplatin-induced toxic side-effects of body weight loss, nephrotoxicity and ototoxicity were significantly reduced functionally or histopathologically by the combined administration of cisplatin and fosfomycin. A comparison of different dosage schedules with a total dose of 10 mg/kg of cisplatin showed that a higher daily dose for a shorter time period produced more marked toxicities.

Alanine Transaminase↗
PubMed1982

Evaluation of ototoxicity of amino-glycoside antibiotics in rabbits.

It is generally accepted that the ototoxicity of aminoglycoside antibiotics is gentamicin (GM) greater than dibekacin (DKB) greater than kanamycin (KM) greater than amikacin (AMK) based on the results of animal experiments. However, clinical data reveals that the ototoxicity caused by each of the aminoglycoside antibiotics does not coincide with the ototoxicity in the animals. The present study was intended histopathologically for comparative evaluation of above-mentioned antibiotics using rabbits. The ototoxicity was GM greater than DKB greater than KM greater than AMK with the dose of 100 mg/kg, which coincide with many of the conventional reports on animal experiments. However, with the dose of 50 mg/kg, the order was GM greater than AMK greater than KM greater than DKB. With the dose of 30 mg/kg, hardly any differences were noted between the ototoxicity of GM and that of AMK. It was found out that the evaluation of the ototoxicity of drugs in high doses does not always correspond to that of lower doses. Therefore, the ototoxicity should be evaluated in strict consideration of dose of drugs. Usually, the doses of drugs used in the ototoxicity studies with animals are more than 10 times higher than those used clinically. Consequently, problems still exist in infering the ototoxicity of drugs in humans directly from the results obtained from animal experiments.

Amikacin↗
PubMed1982

Ototoxicity of aminoglycoside antibiotics by rapid intravenous injection.

The ototoxicity and nephrotoxicity of aminoglycoside antibiotics (dibekacin, gentamicin and kanamycin) administered to rabbits by rapid intravenous or intramuscular injections were histopathologically compared. Comparative evaluations between the two routes were further made concerning the levels of the antibiotics in serum and in perilymph. The results revealed that, although the peak serum level after a rapid intravenous injection was significantly higher than that observed after an intramuscular injection, no differences in the transfer into the perilymph, and in inner ear or renal damage were seen between the two different routes. In other words, the results of the present study did not support the conventional idea that the higher the peak blood levels of the aminoglycoside antibiotics, the greater the risk of damage to the inner ear or kidney.

Aminoglycosides↗