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Biomedical subjects

J Kusakari

Publications and source records attributed to J Kusakari.

At least 19 recordsLinked to original sources
PubMed1995

The effect of the sympathetic nervous system upon susceptibility to acoustic trauma.

This study was designed to determine whether the sympathetic nervous system exerts a protective or enhancing effect in acoustic overstimulation. The compound action potential of the cochlea (CAP) was recorded in guinea pigs while the cervical sympathetic nervous system (SNS) was electrically stimulated or after it was surgically eliminated. The stimulation or the elimination of the cervical SNS has no effect on the threshold of CAP. The threshold shift in CAP after acoustic overstimulation (110, 115, or 130 dB SPL for 10 min) was measured in the cervical SNS stimulation group, in the cervical SNS elimination group, and in the control group. When the animal was under insufficient sedation, there was no difference among these three groups. However, the CAP threshold shift was significantly smaller in the cervical SNS stimulation group than in the other two groups when the animals were sufficiently sedated. The cervical SNS stimulation had some protective effect on the susceptibility to acoustic trauma when the systemic SNS activity was suppressed.

Acoustic Stimulation↗
PubMed1995

Distortion-product otoacoustic emissions in experimentally induced hydropic ears.

The postoperative changes of distortion-product otoacoustic emissions (DPOAEs) and cochlear potentials were examined using 15 albino guinea pigs in which endolymphatic hydrops was induced by obliterating the endolymphatic sac. DPOAEs (geometric mean: 4,6 and 8 kHz) were measured once before and every week after surgery. At the 2nd (n = 5), 4th (n = 5) and 12th (n = 5) postoperative weeks, endocochlear potential (EP) and compound action potential (CAP) were measured. Although the reduction in DPOAEs at 8 kHz was first detected at the 12th week, the amplitude of DPOAEs at 4 and 6 kHz was already reduced at the first week and decreased gradually thereafter. In contrast to these results, the CAP threshold was not elevated at the 2nd week and a slight increase was first detected at the 4th week. The results obtained in the present study suggest that DPOAEs are more sensitive than CAP in detecting the presence of hydrops.

Action Potentials↗
PubMed1995

Effect of acoustic overstimulation on the hydropic ear.

The effect of acoustic overstimulation (2 kHz pure tone) on the compound action potential (CAP) threshold was investigated at frequencies ranging from 2 to 16 kHz using albino guinea pigs, both normal and with experimentally induced endolymphatic hydrops. The hydropic ears were less susceptible to acoustic overstimulation than the normal ears. As the CAP threshold was raised, the frequency exhibiting the greatest CAP threshold shift increased in both animal groups. The tendency was more noticeable in the hydropic ears than in the normal ears. These results are discussed from the aspect of cochlear hydrodynamics.

Action Potentials↗
PubMed1992

Metallic elements in the perilymph measured with an inductively-coupled plasma atomic emission spectrometer.

Metallic elements in the perilymph of the scala tympani in normal and acoustically overstimulated guinea pigs were measured using a new method, an inductively-coupled plasma atomic emission spectrometry. The concentrations of phosphorus and eight metallic elements, i.e. calcium, copper, iron, potassium, magnesium, sodium, lead and zinc were measured simultaneously in a 2 microliters sample of perilymph. The mean concentration values of calcium, copper, iron, magnesium, phosphorus, lead and zinc were 2.03 mM, 38.5 microM, 69.3 microM, 0.822 mM, 0.851 mM, 43.5 microM and 25.0 microM, respectively. There was no significant effect of acoustic overstimulation on the concentrations of these elements except for magnesium, which decreased significantly after the exposure to a intense sound (2 kHz, 115 dB SPL) for 15 min. This is the first report describing the synchronous determination of metallic poly-elements, including copper, iron, lead and zinc, in the perilymph.

Acoustic Stimulation↗
PubMed1992

The hearing of the patients treated with hemodialysis: a long term follow-up study.

Sensorineural hearing loss is frequently found in the patients under the treatment with hemodialysis, but the responsible etiological factor(s) still remains controversial. The purpose of the present study was to determine by a long term follow-up study whether hemodialysis per se or other factors induce sensorineural hearing loss. Thirty-seven patients with the observation periods of 4 years or longer were selected for the analysis. Hearing tests were performed soon after the initiation of hemodialysis and every 3 to 12 months thereafter. Significant hearing loss was found in 16 cases (31 ears) at the first test. Although 3 cases (5 ears) of the initially normal group and one case (2 ears) of the group with already existing hearing loss exhibited significant hearing loss, the change in the hearing level was quite minimal in remaining 67 ears during the observation period. Although the cochlea in patients under the treatment with hemodialysis is susceptible to various insults, we conclude that hemodialysis per se does no harm to the cochlea and the hearing can be maintained at the pre-hemodialysis level in the majority of the cases.

Adult↗
PubMed1992

The effect of crossed olivo-cochlear bundle stimulation on acoustic trauma.

To investigate whether the crossed olivo-cochlear bundle (COCB) functions in a protective manner, albino guinea pigs were exposed to sounds of varying intensity (110-130 dB SPL, 3-30 min) with or without electric stimulation of COCB, and the threshold shifts of the compound action potential (CAP) were examined. A statistically significant protective effect was observed in animals exposed to stimuli of intermediate intensity which induce threshold shifts of 50 to 55 dB on average. No protective effect was observed in the groups exposed to greater or milder stimuli. These results are discussed in the light of the available literature.

Acoustic Stimulation↗
PubMed1992

[Solute movement across the round window membrane in comparison with that across the blood-labyrinth barrier].

The permeability of the normal round window membrane of the guinea pig to trimethylphenylammonium (TMPA) was assessed using ion-selective electrodes and compared with the rate of TMPA entry from the systemic blood circulation into the scala tympani (ST) of the cochlea across the so-called blood-labyrinth barrier. While the round window niche was irrigated with artificial perilymph containing 1 mM TMPA, the TMPA concentration in ST of the basal turn rose rapidly so as to reach 20-50% of the irrigating medium concentration in one hour. Following this procedure, the concentration declined significantly faster when the niche was subsequently irrigated with TMPA-free artificial perilymph than when the niche was left free of any fluid. This result shows that the membrane is fairly permeable to TMPA in both directions. Furthermore, TMPA entry from blood to STs of the basal and third turns was observed while the plasma TMPA concentration was maintained at about 0.5 mM by continuous intravenous infusion of isotonic 50 mM TMPA medium (1 part 150 mM TMPA + 2 parts lactated Ringer solution). TMPA appeared to distribute evenly from the blood to both turns at a much slower rate than across the round window membrane. In another experiment, the round window niche was irrigated with TMPA-free artificial perilymph during the intravenous infusion of 50 mM TMPA medium. The TMPA concentration increase in ST of the basal turn was greatly suppressed, whereas that of the third turn was not affected for at least an hour.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Aicardi syndrome accompanied by auditory disturbance and multiple brain tumors.

We described a 5-month-old girl with Aicardi syndrome accompanied by auditory disturbance and multiple brain tumors. She was admitted to our hospital because she suffered from intractable flexor spasms. Physical examination revealed craniofacial asymmetry, left auricular deformity, scoliosis, and remarkable hypotonia with psychomotor retardation. Abnormal ophthalmological findings included chorioretinopathy with pale and round-shaped peripapillary lacunae, and there was modified hypsarrhythmia in her EEG. MRI revealed multiple brain tumors in the 3rd and the lateral ventricles which are considered to be choroid plexus papilloma with agenesis of the corpus callosum. ACTH therapy was administered because of the intractable seizures. After ACTH therapy, the thresholds of waves I and V were much improved. The interpeak latency of waves I-V of the left ear and the peak latency of wave I of the right ear had been lengthened. Acoustic reflex with contralateral stimulation showed no response in the left ear. These findings indicate that the auditory system is also involved in the Aicardi syndrome and that ACTH is effective for its dysfunction.

Acoustic Impedance Tests↗
PubMed1991

The effect of furosemide on the endocochlear potential in ears with experimentally induced endolymphatic hydrops.

The endocochlear potential (EP) was measured in 38 guinea pigs with experimentally induced endolymphatic hydrops at the 3rd, 6th, 12th and 24th postoperative weeks, and the effects of furosemide (FUR, 50 or 80 mg/kg) on the EP were examined. A time-related reduction of the EP from the normal value and increased susceptibility to FUR were disclosed in the hydropic animals. Furthermore, 24-week animals given 80 mg/kg FUR showed a significantly slower recovery rate of the EP than the other groups, indicating impairment of the strial function progressive with post-operative time. The negative component of the EP was considered to be unimpaired until at least 12 weeks after the surgery.

Animals↗
PubMed1989

Immunological abnormality of the serological tests in bilateral sensorineural hearing loss.

Thirty-one patients with bilateral sensorineural hearing loss were investigated by serological and cellular immune examination, i.e. lymphocyte subsets, circulating immune complexes, autoantibodies, complements, immunoglobulins. Manifest immunological abnormality was demonstrated in 10 patients (32.3%) who were classified into 3 groups. The first group (3 patients) exhibited the presence of immune complex and/or autoantibody with an elevation of B-cell subset which was thought to relate to autoimmune response type II and/or III. The second group (3 patients) was suspected of a cellular immune-mediated response. One patient belonged to both the first and second group. The other 5 patients had immune disturbances induced by viral infection.

Adolescent↗
PubMed1989

Effects of nitrogen mustard-N-oxide on ionic activities of inner ear fluid and ionic permeabilities of the cochlear partition in the guinea pig.

The effect of nitrogen mustard-N-oxide (NMO) on the endocochlear potential (EP) was investigated from the aspect of the ion concentrations and permeabilities in the cochlea. Compared with the untreated animals, in NMO-treated animals 20 to 30 hours after administration, the EP was decreased (30.8 +/- 3.5 mV in NMO versus 82.4 +/- 1.6 mV in control), the K+ concentration in perilymph of the scala tympani was increased (8.2 +/- 1.0 mM versus 5.3 +/- 0.7 mM), the K+ concentration in endolymph was decreased (128.5 +/- 10.6 mM versus 157.9 +/- 7.9 mM), and the Na+ concentration in endolymph was increased (9.6 +/- 3.6 mM versus 2.5 +/- 0.4 mM). The permeability coefficient for Na+ of the cochlear partition in the NMO-treated animals significantly decreased, while that for Cl- significantly increased. The negative EP, which presumably exists in the normal state, diminished further (-2.7 mV versus -27.8 mV), and the calculated electrogenic potential of the EP was depressed remarkably (33.5 mV versus 110.2 mV). The results suggest that the effects of NMO involved changes in ion permeabilities of the partition and the inhibition of electrogenic transport processes in the cochlea.

Animals↗
PubMed1989

Effect of external auditory canal pressure upon the hearing threshold in patients with Menière's disease.

Fluctuation of hearing at low frequencies is one of the most characteristic findings in Meniere's disease and seems to be a phenomenon closely related to changes of endolymphatic pressure and volume. In the present study, pressure was applied to the external auditory canal of patients with Meniere's disease, and the effect on the bone conduction threshold was examined at times of depressed and improved hearing. In more than half of these cases, it was found that the pressure effect was marked at the time of improved hearing acuity, but not at the time of depressed hearing. This effect was also confirmed in more objective experiments with guinea pigs. It is concluded that the fluctuation of hearing in Meniere's disease seems to be a phenomenon accompanying the endolymphatic pressure change in the scala media.

Animals↗
PubMed1989

[Gellé test in patients of Menière's disease and fluctuating low tone hearing loss].

The threshold shift at 500 Hz bone conduction under positive and negative static pressure of 400 mmH2O applied to the external auditory canal was examined in 20 patients of Meniere's disease with fluctuating low tone hearing loss, 21 patients of sensorineural hearing loss without fluctuating and 24 normal controls. In contrast to the 10 to 15 dB threshold shift in the latter two groups (non-fluctuating group, 14.8 +/- 5.1 dB at positive and 11.1 +/- 5.7 dB at negative; normal controls, 13.6 +/- 5.4 dB at positive and 9.3 +/- 5.3 dB at negative), the former showed a significantly smaller shift (3.2 +/- 6.1 dB at positive and 2.3 +/- 4.5 dB at negative) while hearing was depressed. However, when the hearing was improved, the pressure effect became greater even in the former group (11.3 +/- 5.3 dB at positive and 9.1 +/- 4.8 dB at negative). To understand further details of these phenomena, we performed electrophysiological animal experiments. Through a small hole made on the guinea pig's cochlear bony wall, 300 mmH2O pressure was applied to the scala tympani and the threshold of 500 Hz CM was examined in both endolymphatic sac obliterated ears and non-obliterated ears. In 14 non-obliterated ears 21.1 +/- 5.1 dB threshold shift was recorded, whereas it was only 1.6 +/- 2.6 dB in 9 obliterated ears at 4-6th postoperative days. These results seem to reflect that the endolymphatic pressure is great during the early stage of hydrops.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Evaluation of vitamin D metabolism in patients with bilateral sensorineural hearing loss.

The possible role of vitamin D in hearing impairment was investigated by the measurement of three metabolites of vitamin D in 28 patients with bilateral sensorineural hearing loss (BSNHL). Twenty-three of 28 patients showed a significantly decreased level of 1,25-dihydroxyvitamin D3, with a normal value of 25-hydroxyvitamin D3. In addition to experimental and clinical reports regarding vitamin D deficiency, the present study suggests that vitamin D deficiency is one of the etiologies of BSNHL, through the calcium metabolism and microcirculation in the cochlea.

Adolescent↗
PubMed1989

Labyrinthine fistulae caused by cholesteatoma. Improved bone conduction by treatment.

In five cases of labyrinthine fistulae caused by extensive cholesteatoma, more than 30-dB improvement in bone conduction was observed in four postoperative cases and in one case after preoperative administration of antibiotics. In each case, a fistula of more than 2 mm in length was present at the lateral semicircular canal, and membranous labyrinthine wall was exposed when the cholesteatoma membrane was removed. These five cases were considered to be in the stage of serous labyrinthitis. The experience with these cases shows that emergent antibiotic treatment and surgery are appropriate for cases with reduced bone conduction in which labyrinthine fistula caused by cholesteatoma is suspected. In addition, as the reduction of bone conduction does not necessarily preclude the possibility of good postoperative hearing, tympanoplasty may be appropriate even for cases with markedly reduced bone conduction due to labyrinthine fistulae.

Adolescent↗
PubMed1988

Efficacy of defibrinogenation and steroid therapies on sudden deafness.

Effects of defibrinogenation therapy and steroid therapy for sudden deafness were compared by paired double-blind testing. The average hearing recovery for five frequencies (250 to 4000 Hz) was more than 30 dB; overall improvement rate was 57.3% (47/82) for the patients assigned to defibrinogenation therapy and 38.7% (31/80) for the patients assigned to steroid therapy. Thus, the former treatment resulted in significantly better hearing recovery.

Administration, Oral↗