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Biomedical subjects

J Kusakari

Publications and source records attributed to J Kusakari.

At least 37 records · Page 2Linked to original sources
PubMed1996

The effect of methylprednisolone on acoustic trauma.

The effect of methylprednisolone (mPSL) upon acoustic trauma was studied using albino guinea pigs which were exposed to 2 kHz pure tone of 110, 115 or 120 dB SPL for 10 min. After the exposure to intense sound, mPSL of 6, 12 or 40 mg/kg was intraperitoneally given daily for 7 days and the threshold of the compound action potential (CAP) was examined on the 8th day. Compared with CAP of the control animals given physiological saline solution, no significant difference was observed in the CAP threshold shift between the mPSL group and the controls following exposures to the sound of 115 and 120 dB SPL, respectively. However, when the animals were exposed to the sound of 110 dB SPL, the CAP threshold shift was significantly smaller in the mPSL animals than in the controls. The present results indicate that mPSL possesses a therapeutic effect in cases of mild acoustic overstimulation.

Acoustic Stimulation↗
PubMed1995

Effect of asphyxia on the composition of cationic elements in the perilymph.

To elucidate the role of free radicals in the cochlea, cationic elements in the perilymph of the scala tympani in normal and asphyxic guinea pigs were measured by an inductively coupled plasma atomic emission spectrometer. The concentrations of 7 cationic elements (i.e., calcium, copper, iron, magnesium, phosphorus, lead and zinc) were measured simultaneously in a sample of the perilymph taken before, during and after asphyxia. There was no significant change in these cationic elements during asphyxia for 3 min. In contrast to the stationary level during asphyxia, the iron concentration was significantly elevated at 5 min after re-ventilation following asphyxia and decreased rapidly toward the pre-asphyxic level thereafter, although no significant change was observed in other cationic elements. These results were comparable to the theory of non-protein-bound iron accumulation produced by an O2-dependent mechanism during re-perfusion.

Animals↗
PubMed1995

Nuclear transition of heat shock protein in guinea pig cochlea after hyperthermia.

The main reaction of heat shock protein (hsp) 70 family to heat shock is 2-fold, one is an increased synthesis in the cytoplasm and the other is a transition from the cytoplasm to the nucleus. Although the former has been already reported in the cochlea by several authors, there has been no description as to the latter. The present study was designed to determine whether this nuclear transition of hsp70 family is also present in the cochlea as in the other organs. Albino guinea pigs subjected to hyperthermia treatment (42 degrees C, 10 min) were killed at 0, 6, 18 or 24 h after the cessation of hyperthermia treatment. Immunohistochemical studies in the cochlea of the untreated animals revealed anti-hsp70 family immunoreactivity mainly in the cytoplasm of the various cells in the cochlea, including the interdental cells, the spiral ganglion cells or the outer hair cells. However, immunoreactivity remarkably increased in the nucleus immediately after the cessation of hyperthermia treatment and this increased immunoreactivity disappeared at 6 h or later. It is concluded that the nuclear transition of hsp70 family also takes place under hyperthermal stress in the cells of the cochlea as in other organs.

Animals↗
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

Congenital ossification of the stapedius tendon: diagnosis with CT.

PURPOSE: To describe the features of congenital ossification of the stapedius tendon at thin-section computed tomography (CT). MATERIALS AND METHODS: Thin-section CT scans, clinical records, and surgical findings were retrospectively evaluated in nine ears of five patients with surgically proved congenital ossification of the stapedius tendon. Thin-section CT scans of 50 control ears were also reviewed. RESULTS: On thin-section CT scans, a linear area of soft-tissue attenuation was demonstrated between the monopod stapes and the pyramidal eminence (nine ears), as well as thickening of the stapes footplate (two ears). In the 50 control ears, the normal stapes tendon was not clearly seen on thin-section CT scans. CONCLUSION: At CT, a linear area of soft-tissue attenuation that extends from the pyramidal eminence to the monopod stapes is suggestive of congenital ossification of the stapedius tendon or a bony bar adjacent to it.

Adolescent↗
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↗
PubMed1994

Free vascularized iliac osteomusculocutaneous flaps based on the lateral circumflex femoral system for repair of large mandibular defects.

A free vascularized iliac osteocutaneous flap based on the ascending and transverse branches of the lateral circumflex femoral system was studied by cadaveric investigation. These composite flaps were successfully used in 2 patients with both large mandibular and soft-tissue defects. The advantages of this flap are that (1) the distal portion of the flap is relatively thin, (2) the pedicle vessels are long and large, (3) the skin territory is extremely wide, (4) repositioning of the patient during the operation is unnecessary, (5) the flap can be elevated while the recipient mandibular region is resected by two teams because the donor site is far from the head and neck regions, (6) the donor scar is in an unexposed area and its location permits easy concealment, and (7) subtotal loss of the mandible can be reconstructed with the use of split crests from either side of the ilium because the external and the internal cortices are fed independently by the lateral circumflex femoral and the deep circumflex iliac systems. This appears to be a new concept for reconstruction of total mandibular loss.

Aged↗
PubMed1993

Pharmacokinetics of furosemide in endolymph.

To investigate the pharmacokinetics of organic anions in the endolymph of the guinea pig, 100 mg/kg furosemide, an organic anion, was intravenously given to measure the concentration in the cochlear endolymph by high-performance liquid chromatography with fluorescence detection. In the endolymph, the concentration of the furosemide increased slowly for 1 hr to 1.6 micrograms/ml and gradually declined thereafter. Pretreatment with 200 mg/kg probenecid, an anion transport inhibitor, had no effect on the furosemide elimination in the endolymph except on the concentration at 2 hr. This was contrary to the drastic change observed in the perilymph of the scala tympani by the same pretreatment. Analogous to the effect in the endolymph, probenecid showed no change in the concentration of the serum, while a pronounced gradient of furosemide concentration existed between them. The present results suggest that the furosemide passively transfers from blood to the endolymph at a relatively low penetrability.

Animals↗
PubMed1993

Intrusion of an incisor tooth into the contralateral frontal sinus following trauma.

Although intrusions of glass fragments into the frontal sinuses are not uncommon in traffic accidents, a case with a tooth in the frontal sinus has never been reported. We report a patient with traumatic inclusion of an incisor tooth in the contralateral frontal sinus. Radiographic investigations demonstrated the tooth in the frontal sinus though no skin damage was recognized on the upper face. The usefulness of CT scan in localizing the missing tooth after facial trauma and its route of entry into the contralateral frontal sinus is discussed.

Accidents, Traffic↗
PubMed1993

The effect of endocochlear potential suppression upon susceptibility to acoustic trauma.

In the present study we investigated the influence of decreased endocochlear potential (EP) on acoustic trauma. Guinea pigs with decreased EP following i.v. administration of furosemide (FUR) and normal EP given physiological saline solution (PSS) i.v. instead of FUR were exposed to 2 kHz pure tone ranging from 110 to 130 dB SPL for 5 min. The input-output curves of the compound action potential (CAP) before acoustic overstimulation were compared with those at 2 h after the exposure. In 125 and 130 dB SPL exposure there was no difference in threshold shift between the FUR and PSS groups. In 115 and 120 dB SPL exposure, however, the threshold shift of the FUR group was significantly smaller than that of the PSS group. There was no significant difference between the two groups in 110 dB SPL exposure. These results indicate that the threshold shift of the CAP is mainly due to excessive vibration of the basilar membrane in the greater stimulus groups (125-130 dB SPL) but that the energy exhaustion of the hair cells to a certain extent participates in the threshold shift when the stimulus is milder (115-120 dB SPL). It is concluded that susceptibility to acoustic trauma of a milder intensity (115-120 dB SPL) is reduced when the energy consumption rate of the organ of Corti is decreased by EP suppression.

Acoustic Stimulation↗
PubMed1993

[Effects of acoustic overstimulation and perilymph perfusion--with Joro spider toxin on the concentrations of amino acids in the perilymph].

Glutamate (Glu) is considered one of the most probable neurotransmitter candidates in primary afferent nerves of the cochlea. In the present study, the amino acid profile in the perilymph was determined in order to investigate the effects of acoustic overstimulation and perilymph perfusion with Joro Spider Toxin (JSTX), a specific antagonist of the quisqualate sensitive Glu receptor, on the stimulus-induced release of Glu. In the first series of experiments (control group; n = 10), samples of the scala tympani perilymph (PST) were collected from albino guinea pigs at 60 and 75 min after initiating cochlear perfusion with an artificial perilymph. In the second series of experiments (acoustic overstimulation group; n = 7), the PST samples were collected before (at 60 min after the initiation of perilymph perfusion) and after (at 75 min after the initiation of perilymph perfusion) exposure to a pure tone (2000 Hz, 110 dBSPL for 15 min). In the third series of experiments (JSTX group; n = 8), the PST samples were collected as described above under condition of cochlear perfusion with an artificial perilymph containing of 3.54 x 10(-8) M and 3.54 x 10(-6) M of JSTX. The concentrations of Glu, aspartate, glycine, alanine and leucine were measured by high-performance liquid chromatography (HPLC) using phenylisothiocyanate derivatization. There was no significant effect of acoustic overstimulation or perilymph perfusion with JSTX on the levels of amino acids.(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Stimulation↗
PubMed1993

[Studies on the generation mechanism of non-biological response in distortion product OTO-acoustic emission].

We investigated the effect of non-biological artifacts on the measurement of distortion product oto-acoustic emission (DPOAE) using guinea pigs, and the generation mechanism of this phenomenon is discussed in the present paper. When a sound pressure of a stimulating tone was too large, an overtone was produced within the acoustic probe. When the difference in sound pressure between f1 and f2 was too large, artifacts appeared at frequencies of 2f1-f2 or 2f2-f1. Similar responses were generated when f1 and f2 were identical in sound pressure but exceeded a certain critical level. These non-biological responses could be easily differentiated from biological responses by subjecting the animal to anoxia. The input-output curve of DPOAE was biphasic and clearly showed this critical level in each animal. The results obtained in the present study suggest that the levels of f1 and f2 should be almost equal and should not exceed the observed critical level when measuring DPOAE.

Acoustic Stimulation↗
PubMed1993

[Biochemical profile of proteoglycans and glucosaminoglycans of the mammalian tectorial membrane].

The tectorial membrane is an acellular connective tissue which plays an essential role in cochlear function. While a comparatively large amount of information is available on the collagen network of the tectorial membrane, studies on the biochemical nature of this highly hydrated matrix, which is composed of proteoglycans (PGs) and glycosaminoglycans (GAGs), have been quite limited. Previous reports on the biochemical analysis of the tectorial membrane have failed to detect uronic acid, which is present in large amounts in all mammalian GAGs except keratan sulfate. Applying a colorimetric assay based on the binding of GAGs to cationic dye Safranin-0 in combination with enzymatic techniques, we were able to measure GAGs in the murine tectorial membrane. Approximately 0.3% uronic acid-containing GAGs (mainly in the form of chondroitin/dermatan sulfate) and 0.17% keratan sulfate were detected in the tectorial membrane (both on a wet weight basis). In addition, various types of electrophoresis revealed one large PG with a molecular mass similar to that of the large type cartilage PGs and three small PGs, containing chondroitin sulfate and keratan sulfate side chains, respectively. Judging by coelution of standards, one of the small PGs seemed to correspond to fibromodulin, which has at least one keratan sulfate side chain, and binds to type I and type II collagen to regulate collagen organization in tissues. Our results suggest: (1) Donnan equilibrium is established in the tectorial membrane because sulfated GAGs are highly negatively charged and consequently bring about an influx of large amounts of water and cations into the matrix.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
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↗