Biomedical subjects

M Kenmochi

Publications and source records attributed to M Kenmochi.

16 recordsLinked to original sources

PubMed1999

Cochlear function of guinea pigs with experimental chronic renal failure.

This study aimed to evaluate electrophysiologically the cochlear function of guinea pigs that underwent a five-sixths nephrectomy and, additionally, to explore the synergistic action between chronic renal failure (CRF) and noise. Cochlear potentials were recorded at 1, 2, and 3 months postoperatively. Slight changes in compound action potential and cochlear microphonics were seen at 1 month postoperative, while moderate and profound changes were seen at 2 and 3 months. Endocochlear potential showed no significant reduction. The results indicate that CRF may be an etiologic factor for cochlear dysfunction and that the hair cells seem likely to be a main site of the lesion. One-month-postoperative animals were exposed to a broadband noise. In contrast to control animals, the test animals demonstrated no recovery from the decrease in compound action potential and cochlear microphonics that occurred immediately after noise exposure. This suggests a synergistic interaction between CRF and noise.

Animals↗

PubMed1998

Salicylate and quinine selectively increase spontaneous firing rates in secondary auditory cortex.

This study presents firing rates for simultaneously recorded spontaneous and stimulus driven multi-unit activity in primary auditory cortex (AI), anterior auditory field (AAF) and secondary auditory cortex (AII) in cats before and after application of salicylate or quinine. From 21 cats, in three cortical areas simultaneously, a total of 1533 multi-unit files were obtained. The data suggest (1) that both salicylate and quinine significantly increase spontaneous firing rates in AII, whereas in AI and AAF both quinine and salicylate reduced the spontaneous rate; (2) the effect of both drugs was to increase spontaneous rates for recording sites with high characteristic frequency (CF) and a tendency to decrease them for low CF sites; (3) the mean stimulus driven firing rates were not affected by either drug except for a decrease produced by quinine in AI; (4) changes in driven firing rate were positively correlated with changes in spontaneous firing rates. This suggests that tinnitus inducing agents selectively increase spontaneous firing rates in the extralemniscal pathway.

Acoustic Stimulation↗

PubMed1998

[The effects of high-dose steroid therapy on sudden deafness].

The effect of high-dose steroid therapy on sudden deafness were investigated in 19 cases. A daily intravenous administration dose of hydrocortisone sodium succinate was tapered from 800 mg to 200 mg as follows; 800 mg 800 mg, 600 mg, 600 mg, 400 mg, 400 mg, 300 mg, and 200 mg. Another 19 cases, the control group, were treated with intravenous application of prednisolone, tapered from 50 mg to 10 mg in 10-mg steps and each dose applied for 3 days. There were no significant differences in the effect on hearing between the two groups as measured by three different analyses: criteria proposed by the Committee on Sudden Deafness of the Japan Health Ministry; magnitudes of improvement of mean thresholds at five frequencies from 250 Hz to 4 kHz in affected side; and the ratio of the magnitudes of improvement of mean thresholds in affected side to magnitudes of difference between the initial mean thresholds in affected side and those in contralateral side. These findings suggest that high-dose steroid therapy for sudden deafness is not so effective as it is for idiopathic facial palsy. This may be due to the difference in the mechanisms of development between the two conditions. No critical side effects were observed in our study, which would argue for the safety of our method of high-dose steroid therapy for routine clinical use. It might be advisable to conduct additional clinical studies to determine the effect of high-dose steroid therapy for sudden deafness, because our study was conducted on a small number of patients and was not double-blind or randomized.

Adolescent↗

PubMed1997

Autonomous cortical rhythms affect temporal modulation transfer functions.

A correlational study between the dominant frequencies in the spontaneous local field potential and the single unit's best modulation frequency (BMF) for periodic click train stimulation in the primary auditory cortex of the cat is presented. Data were obtained from 251 single units recording in 29 cats. The correlation between spindle frequency (mean 8.2 Hz) and BMF (mean 9.3 Hz) was significant (r2 = 0.58, p < 0.0001). The limiting click-following rate was negatively correlated with the strength of the spindle rhythm: the longer the oscillation the lower the limiting rate. This suggests that the click-following responses of the primary auditory cortex depends as much on ongoing autonomous activity as it does on stimulus-induced activity.

Acoustic Stimulation↗

PubMed1997

Salicylate and quinine affect the central nervous system.

Spontaneous local field potential (LFP) spindle frequencies in cat primary auditory cortex (AI) were estimated from the LFP-trigger autocorrelogram before and after application of sodium salicylate and quinine sulfate. A significant decrease (from 8.7 Hz to 7.6 Hz) was observed. The best modulation frequencies for 251 single units recorded in AI response to periodic click train stimulation also decreased (from 10 Hz to 8.6 Hz) after application of these tinnitus-inducing drugs. The results strongly suggest a central effect of salicylates and quinine in addition to their peripheral ototoxic effects.

Acoustic Stimulation↗

PubMed1997

[Functional changes in the cochlea of guinea pigs in chronic renal failure--electrocochleography. Effect of noise exposure].

An animal model of chronic renal failure (CRF) was created by the 5/6 nephrectomy procedure in guinea pigs. Levels of serum Cr and BUN were abnormally elevated at 1,2 and 3 months after the procedure. ECoG (CAP, CM) was recorded through a silver ball electrode placed on the round window 1,2 and 3 months after surgery. EP was measured with a glass microelectrode from the scala media via the round window membrane. Only slight ECoG changes were seen 1 month after surgery. On the other hand, moderate or profound changes were observed 2 and 3 months after-surgery. No significant decrease in EP was found in the post-surgery animals which distinctly showed abnormal CAP, CM, although a limited number of animals were studied. The above results indicate that CRF is one of the etiological factors of cochlear dysfunction and the sensory hair cells appeared to be the site of the lesion. To study the interaction between noise exposure and CRF, 1 month post-surgery animals with only a little change in ECoG were exposed to a broad band noise. Changes in the ECoGs were followed up for 6 hours after the noise exposure. In contrast to the controls, animals with CRF did not recover from the reduced ECoG which occurred immediately after the noise exposure. This suggests synergistic interaction between noise and CRF.

Animals↗

PubMed1996

Yearly variation of spontaneous somatic mutation frequency in the stamen hairs of Tradescantia clone KU 9 grown outdoors, which showed a significant increase after the Chernobyl accident.

Scoring of spontaneous somatic pink mutation frequency in the stamen hairs of Tradescantia clone KU 9, a heterozygote for flower color (blue/pink; the blue color being dominant), was carried out for 11 years on plants grown outdoors, during the period of May 11-31 (for 3 weeks) in every year from 1982 to 1992. Weekly and yearly variations of the spontaneous mutation frequency were observed, and such variations could mostly be correlated to the difference in temperature. That is, the mutation frequency was generally higher in the weeks and years when the temperature was relatively low, showing the strongest negative correlation with the average minimum temperature. The variations were also correlated to the diurnal temperature difference, the mutation frequency being higher with larger diurnal temperature difference in general. However, the mutation frequency observed in 1986 was exceptionally higher than that expected from the temperature for this year, and was very significantly higher than for other years. The scoring of mutation frequency was thus continued in 1986 for an additional 4 weeks (June 1-28), and it was confirmed that such higher mutation frequencies lasted for 6 weeks in total. The exceptionally high mutation frequency seemed to be related to the radioactive fallout which occurred in early to mid May of 1986, even in Japan, after the serious nuclear reactor accident at Chernobyl, and also to the biological concentrations of radioactive nuclides which subsequently occurred, although it was difficult to conclude this definitely. The mutation frequency in 1987 was second highest, and was also significantly higher than the lowest mutation frequency observed in 1990.

Climate↗

PubMed1996

Diagnostic significance of electrocochleogram and auditory evoked brainstem response in totally or subtotally deaf patients.

This paper examined the use of ECoG and ABR in 7 patients with totally or subtotally deaf ears. The patients included one with cortical deafness, one with psychogenic deafness, one with intrapontine hemorrhage, and 4 with acoustic neuroma. In patients with substantial hearing loss, ECoG should be performed first if retrocochlear disorders are suspected since results may be obtained even in the absence of other auditory evoked potentials. Simultaneous ABR measurements can be effective when localizing retrocochlear lesions. ECoG can also help to determine the need for preserving hearing during surgery for retrocochlear lesions by indicating the degree of cochlear function.

Adult↗

PubMed1996

Abnormal electrocochleography after excision of acoustic neuroma.

Pre-, per- and post-operative ECoG findings obtained from a 43-year-old woman with an acoustic neuroma were studied. Although CAP presented a normal waveform in response to click during the whole process of the operation, it was transformed into an abnormally broadened negative waveform in shape with a mild hearing exacerbation, and has remained unchanged up to the present. This broad response was considered to be a receptor potential, because it showed no adaptational amplitude reduction. Additionally, postoperative ECoG to tone burst stimuli demonstrated an increase in DC potential following the stimulus envelope. Consequently, the broad negative response to click was considered to be mainly composed of an enlarged negative SP. The generation mechanism underlying the phenomenon of an abnormally increased negative SP found after the excision of an acoustic neuroma is discussed, with reference to several items in the literature. Similar responses in the postoperative ECoG of patients with acoustic neuromas obtained by us in the past were given as additional examples. CAP as an indicator for intraoperative monitoring can hardly predict postoperative auditory function. It is to be hoped that a more reliable auditory monitoring method during the operation will be established.

Adult↗

PubMed1996

Acute sensorineural hearing loss caused by Mycoplasma pneumoniae.

Four cases with acute sensorineural hearing loss on one side and one case with bilateral ear fullness associated with Mycoplasma pneumoniae (MP) were described. These cases were characterized by highly elevated MP complement fixation titer, and cold hemagglutinin titer. All patients experienced cochlear symptoms in an early stage following common cold. In all cases, clarythromycin (CAM) had been administered for 10 days, and adenosine triphosphate (ATP), vitamin B1, B12, and prednisolone were concurrently administered for 14 days. Two cases with acute hearing loss and one case with ear fullness returned to normal hearing after treatment. The other cases were remarkably improved in hearing level. MP is a common causative agent for protein respiratory disease. The true incidence of hearing loss in this disease may be higher than has been reported so far. Prompt diagnosis possibly facilitates the administration of specific treatment and leads to good prognosis.

Adult↗

PubMed1996

Antibodies of type II collagen and immune complexes in Menière's disease.

In a previous study, we showed that endolymphatic hydrops was induced in 36% of guinea pigs immunized with type II collagen and that dominant negative summating potential (SP) was recorded for these hydropic animals. In the present study, we evaluated the levels of serum antibody to type II collagen and three other immune indexes in patients with Menière's disease, especially those who showed negative SP dominance in ECoG. Twenty-nine Menière's cases, 22 normal volunteers serving as controls, 28 rheumatoid arthritis (RA) cases, and 9 patients complaining of vertigo were examined to detect serum immune indexes. Menière's patients exhibited high values of serum anti-type II collagen antibody compared with control subjects. Furthermore, total IgG, C3, anti-type II collagen antibody and CIC were increased with the highest levels being in the RA group, followed by Menière's disease group and then the control group. These results probably reflect the extent of immune reaction development. The immune response may be generalized in RA cases and/or local in Menière's disease. These results suggest the development of certain immune status abnormalities in our cases, which lends support to the idea of immunologic disorder playing a role in the etiology of some cases of Menière's disease.

Adult↗

PubMed1996

Effects of administration of high dose hydrocortisone on Bell's palsy.

As an improved maintenance therapy for Bell's palsy, Stennert recently introduced large-dose steroid administration in the early stage of the disease with i.v. infusion of low-molecular dextran. The steroid administration aims at improving the microcirculation. This therapy achieved a 96% complete healing rate. However, because of side-effects such as hepatic and renal disorders or gastric ulcer, this therapy has not been widely used. In the present study, we investigated an improved treatment method based on Stennert's method. It has a much lower incidence of side effects, and can be used in routine clinical practice. The medicines employed in our therapy were hydrocortisone sodium succinate (Solu-cortef), hydroxymethylated starch (Hespander) and D-mannitol (Manitol). Subjects were 53 Bell's palsy patients for whom treatment could be started within 2 weeks from the onset of the disease. Curative rate in the patients who received large-dose administration of Solu-cortef was 96.2% in the 24th week, and the therapy was considered to be applicable in routine clinical practice for Bell's palsy.

Adolescent↗

PubMed1996

Effectiveness of formula ophiopogoins in the treatment of xerostomia and pharyngoxerosis.

A multicenter study was carried out in 24 institutions in Kanagawa Prefecture, Japan. The subjects were 113 male and 145 female patients, ranging in age from 28 to 86 years (mean 63.7) who complained of dryness of the mouth and throat. The following illnesses were diagnosed: xerostomia and pharyngoxerosis in 161, radiation xerostomia and pharyngoxerosis in 56, chronic pharyngitis with dry mouth and throat in 22, and Sjögren's syndrome in 7. Eleven patients had other symptoms. The subjects were given a 3-g pack of granules of formula ophiopogoins three times a day before a meal. Their subjective symptoms and objective signs were examined prior to, 2, and 4 weeks after the beginning of therapy.

Adult↗

PubMed1996

Two cases with glossopharyngeal neuralgia treated by nerve reaction: oropharyngeal approach.

Two patients with idiopathic glossopharyngeal neuralgia received glossopharyngeal nerve resection by the oropharyngeal method, and their symptoms were relieved. Both patients had suffered proxysms of severe pain in the unilateral glossopharyngeal innervation for many years, and pharmaceutical treatment had been made in vain and, although surgical intervention in one patient had resulted in temporary relief, it had not been possible to prevent recurrence. As the identification of trigger zones by the method of local nerve block caused us to think that surgical treatment would be more effective in both patients, the glossopharyngeal nerve was resected, using the oropharyngeal method, with a view to attaining permanent symptomatic relief. Consequently, satisfactory results were obtained.

Female↗

PubMed1993

A cultured skin substitute composed of fibroblasts and keratinocytes with a collagen matrix: preliminary results of clinical trials.

The cultured skin substitute was created through successive cultivation of fibroblasts and keratinocytes that were combined within a collagen matrix. This collagen matrix was composed of a collagen spongy sheet and a collagen gel. The collagen spongy sheet was designed to produce a honeycomb structure having many holes in which all holes through the sheet were filled with collagen gel. This specific structure thereby allows for the nourishment of the cultured keratinocytes on the surface of the matrix when placed on the graft bed. In this study, autologous cultured skin substitute was applied to a 51-year-old man who had sustained a burn injury. Three sheets of the cultured skin substitute (6 x 9.5 cm) were grafted onto the full-thickness excised wound in the right anterior chest wall. One week after grafting most of the matrix disappeared and stratified keratinocytes were seen to have firmly attached to the underlying tissue. Five weeks after grafting a cornified epidermal layer was seen. Ten months after grafting a mature epidermis and a well-differentiated papillary and reticular dermis replacement were observed. The physical properties and color of this grafted area resemble those of normal skin. In the second test case, autologous cultured skin substitute was applied to a 30-year-old man with a scar remaining after tattoo removal. Eight sheets of the cultured skin substitute (10 x 18 cm) were applied on an excised wound (thickness, 0.02-0.025 in.) of both the fore- and upper arms. The histological appearance of a biopsied skin specimen from the grafted area at 3 months after grafting showed a mature epidermis and a well-differentiated reticular dermis replacement. The regenerated skin at 14 months after grafting showed an excellent result.

Adult↗

PubMed1992

A silver-sulfadiazine-impregnated synthetic wound dressing composed of poly-L-leucine spongy matrix: an evaluation of clinical cases.

The management of severe burns requires the suppression of bacterial growth, particularly when eschar and damaged tissue are present. For such cases, silver sulfadiazine (AgSD) cream has been traditionally applied. This antibacterial cream, however, cannot be used in conjunction with a temporary wound dressing that is needed to promote healing. The authors developed a synthetic wound dressing with drug delivery capability for clinical use by impregnating a poly-L-leucine spongy matrix with AgSD, which is released in a controlled, sustained fashion. In general, the dressing adhered firmly to the wound in the case of superficial second-degree burns, and during the healing process it separated spontaneously from the re-epithelialized surface. In the management of deep second-degree burns where eschar and damaged tissue were present, the dressing had to be changed at intervals of 3 to 5 days until it adhered firmly to the wound. Once the dressing had firmly attached to the wound, it was left in place until it separated spontaneously from the re-epithelialized surface. Dressing changes were fewer than with other treatments and the pain was effectively reduced. Cleansed wounds were effectively protected from bacterial contamination. Of 52 cases treated with this wound dressing, 93% (14/15) of superficial second-degree burns, 75% (3/4) of deep second-degree burns, 85% (6/7) of superficial and deep second-degree burns, and 75% (12/16) of split-thickness skin donor sites were evaluated as achieving good or excellent results.

Adult↗