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Biomedical subjects

K Kaga

Publications and source records attributed to K Kaga.

At least 37 records · Page 2Linked to original sources
PubMed2001

Effect of furosemide on basal lamina anionic sites in guinea pig labyrinth.

The authors studied the effects of acute furosemide administration on the basal lamina (BL) anionic sites in the stria vascularis, ampullar crista, and endolymphatic sac by using cationic polyethyleneimine (PEI). Furosemide was intravenously administered to albino guinea pigs with normal Preyer's reflexes. After 20 minutes, the bony labyrinth was removed and processed for histologic evaluation. Under a transmission electron microscope, a marked enlargement of the intercellular spaces was observed in the stria vascularis. The PEI distribution decreased significantly on the capillary BL in the stria vascularis and on the subepithelial BL in the sensory, transitional, and dark cell areas. However, no significant change was observed on the capillary BL or the subepithelial BL in the endolymphatic sac. These findings suggest that acute furosemide administration severely alters the distribution of the anionic sites in the strial capillary BL and in the subepithelial BL in the ampullar crista, but not in the capillary BL or the subepithelial BL of the endolymphatic sac.

Animals↗
PubMed2001

Geometric characterization of the laryngeal cartilage framework for the purpose of biomechanical modeling.

Some new anatomic data on the laryngeal cartilage framework have been obtained for the biomechanical modeling of the larynx. This study attempted to define and measure some biomechanically important morphometric features of the laryngeal framework, including both the human and the canine laryngeal frameworks, because the canine larynx has been frequently used as an animal model in gross morphology and in physiological experiments. The larynges of 9 men, 7 women, and 9 dogs were harvested and dissected after death. Linear and angular geometric measurements on the thyroid cartilage, the cricoid cartilage, and the arytenoid cartilage were made with a digital caliper and a protractor, respectively. The results are useful for constructing quantitative biomechanical models of vocal fold vibration and posturing (abduction and adduction), eg, continuum mechanical models and finite-element models of the vocal folds.

Adult↗
PubMed2001

An isolated and sporadic auditory neuropathy (auditory nerve disease): report of five patients.

Five patients of various ages with difficulty in speech discrimination were evaluated. All showed evidence of abnormal auditory brainstem responses (ABRs) beginning with the VIIIth cranial nerve. Broad summating potentials were evoked on their electrocochleograms (EcochGs) and they all exhibited almost normal cochlear outer hair cell function by otoacoustic emissions (OAEs) recordings. Behavioural audiometric testing revealed a mild to moderate elevation of pure-tone threshold in all patients. The shape of their pure-tone losses varied, being predominantly low-frequency in four patients (rising slope pattern) and flat across all frequencies in one patient. Speech intelligibility scores of all patients were poor and out of proportion to what would have been expected if threshold elevation of pure-tone was of cochlear origin (i.e. markedly poor scores on the speech audiogram with good scores on the auditory comprehension test). Patients were neurologically normal when the hearing impairment was first manifested. We suggest that this type of hearing impairment is due to an isolated and sporadic disorder of auditory nerve function. It occurs in isolation and does not seem to be part of a generalized neuropathological process.

Adolescent↗
PubMed2001

[Congenital rubella syndrome developing after a 1987-1988 epidemic in Japan].

Since vaccination legislation was revised in 1994, rubella vaccination has been changed from application to all junior high school girls with no history of clinical rubella to application to individual infants and junior high school students. This may decrease the vaccination acceptance rate and increase the chance of pregnant women's infection with rubella causing congenital rubella syndrome (CRS). We studied 5 children with CRS developed after a 1987-1988 epidemic in Japan to determine how their mothers were infected, and reviewed auditory findings. They were CRS-confirmed or CRS-compatible cases who met CRS diagnostic criteria formulated by the U.S. Center for Disease Control (CDC) in 1983. Two mothers had not been vaccinated because this was not legislated when they were in junior high school. Three were eligible for vaccination at 14, but 2 were not vaccinated. The children were born in 1991-1997. Complications were low birth weight in 3, delay in neck stabilization in 2, and cataract in 1. No case was serious. Ages at first ENT examination ranged from 3 months to 1 year and 8 months. ABR showed hearing loss of > or = 90 dBnHL. They started using hearing aids at 6 months to 1 year and 10 months. Tsumori mental development tests showed delays in developmental age in 2 who started auditory training after ages of 1 year and 6 months. Findings indicated that infants, students, and potentially pregnant women should be vaccinated. Complete serologic testing are important in pregnant women and fetal rubella infection should be diagnosed early by PCR.

Adult↗
PubMed2001

Binaural interaction of bone-conducted auditory brainstem responses.

Bone-conducted auditory brainstem responses (ABRs) elicited by monoaural stimulation are very useful for evaluating hearing in children with congenital atresia of both ears. In a previous study of sound lateralization in children with congenital atresia of both ears, using bilateral bone-conducted stimuli, we found that most of the children could sufficiently retain binaural hearing ability in terms of both intensity and time differences. In this study we attempted to record bilateral bone-conducted ABRs in normal subjects in order to explore binaural interaction objectively. The study revealed that binaural interaction exists in bone-conducted ABRs. This can be taken as neurophysiological evidence that sound lateralization can be detected by children with bilateral microtia and atresia.

Adult↗
PubMed2001

[Current condition of early peripheral lung cancer and related problems].

Early peripheral lung cancer is defined as a tumor whose diameter is within 20 mm and that has not metastasized to lymph nodes. We developed thoracoscopic surgery (two windows method) in 1993. We have been conducting this thoracoscopic surgery in early peripheral lung cancers to identify possible indications as well as to clarify problems related to early peripheral lung cancer. The subjects of this study were 176 tumors, with diameters within 30 mm, including 97 lung cancers with diameters within 20 mm. Of the 97 tumors 20 mm or less in diameter, 18 were N 1 or more severe (N 1, 8 cases: N 2, 10 cases). One patient (N 2) died of bone metastasis and two patients died due to diseases other than lung cancer. Nearly 20% of the patients with tumors 20 mm or less were in the advanced stage, suggesting that mediastinal lymph node resection is necessary. Based on these results, it is advisable to define tumors with a diameter of no more than 10 mm as early peripheral lung cancer.

Adenocarcinoma↗
PubMed2000

bFGF induces differentiation and death of olfactory neuroblastoma cells.

Olfactory neuroblastoma (ONB) is a highly vascularized and malignant tumor arising in olfactory neuronal precursors from the paranasal sinuses. Previously, we showed that treatment of JFEN cells with transforming growth factor (TGF)-alpha caused them to differentiate and respond to chemical odorants, whereas basic fibroblast growth factor (bFGF) treated cells differentiated and died. In the present study we show that established ONB tumors treated with bFGF upregulate the bFGF receptor (FGFR1) prior to differentiation. This cellular differentiation was evidenced by bFGF-induced expression of the human runt homologue AML1 (PEBP2 alpha B, CBFA-2) that is highly expressed in developing olfactory neuroepithelium and TrkA, a preferred nerve growth factor receptor. Since TrkA is expressed in supporting cells, but not in mature olfactory neurons, we hypothesize that the expression of AML1 and TrkA in bFGF-treated JFEN cells induced supporting cell differentiation. Collectively, these results have implications for the treatment of patients afflicted with ONB.

Animals↗
PubMed2000

Temporal stream of cortical representation for auditory spatial localization in human hemispheres.

We measured human evoked magnetic fields to binaural sounds with an interaural time delay as a cue for auditory localization. By analyzing the topography of auditory-evoked magnetic fields in the middle-latency, we demonstrated that particular cortical regions represent the direction of sound localization by their activity level. Upon presenting a binaural sound, the first representations were found in the middle frontal region as well as the superior temporal region of the right hemisphere approximately 19 ms after the stimulation, but their patterns differed. Other cortical regions including the prefrontal and parietal spatial areas were affected within roughly 60 ms. The results showed that the right hemisphere is dominant even in the preattentive stage of auditory spatial processing of sounds from different directions.

Acoustic Stimulation↗
PubMed2000

Mandibulofacial dysostosis: CT evaluation of the temporal bones for surgical risk assessment in patients of bilateral aural atresia.

We present the results of detailed CT investigation of nine patients with mandibulofacial dysostosis (MFD). We also graded the severity of microtia according to Marx's classification system. The results revealed a positive correlation between the severity of microtia and the severity of deformity of the external auditory canal, and attic formation. In 13 ears, the stapes was not adequately visualized to allow any comment on its form. The angle of the first genu of the facial nerve ranged from 55.0 to 123.6 degrees (mean +/-S.D.; 99.5 +/-18.5 degrees ), indicating that this angle is more obtuse in MFD patients than in normal subjects. The eustachian tube and tympanic sinus were present in all the ears examined. None of the patients had mastoid pneumatization. In four ears, the lateral semicircular canal was dysplastic. Eleven ears of six patients scored less than 5 in the grading system developed by Jahrsdoerfer for assessment of the suitability for atresia surgery. These findings indicate that most patients with mandibulofacial dysostosis are poor surgical candidates.

Child, Preschool↗
PubMed2000

Otoacoustic emissions and auditory brainstem responses after neonatal hyperbilirubinemia.

Severe hyperbilirubinemia often results in hearing loss. Behavioral audiometry, auditory-evoked brainstem responses (ABRs) and otoacoustic emissions (OAEs) were performed in three such patients in an attempt to localize the pathophysiology of this hearing loss. Behavioral audiometric findings in these patients (all male, 4, 15 and 25 years old) ranged from severe in the 4-year-old, moderate in the 15-year-old and slight in the 25-year-old. Where obtained, ABR wave V thresholds were elevated or ABR were absent. However, absolute and inter-wave latency measurements were not indicative of brainstem pathology. OAEs (transient and distortion product) could only be obtained in the high- or low-frequency ranges in these patients. Our findings suggest that at least some lesions producing hearing loss in severe hyperbilirubinemia are in the cochlea, especially at the outer hair cells. Finally, we found that only moderately elevated serum bilirubin levels (<20 mg/dl) may contribute to the development of sensorineural hearing loss.

Adolescent↗
PubMed2000

Extended high-frequency ototoxicity induced by the first administration of cisplatin.

The ototoxicity induced by cisplatin results in high-frequency hearing loss. The sound-pressure thresholds at extended high frequencies of 8 to 20 kHz were measured in 12 patients with head and neck cancer before and after the first administration of cisplatin. Ototoxicity was defined statistically by the newly introduced regression-line analysis. This analysis revealed that the threshold of 1 of the 12 patients increased evenly from 8 to 10 kHz, and the damage to the hearing system of this patient was permanent. The reasons for such a low rate of ototoxicity might be the long-term administration of low doses of cisplatin and the addition of fosfomycin.

Adult↗
PubMed2000

Frequency compression hearing aid for severe-to-profound hearing impairments.

OBJECTIVE: Objective of this study is to know how a frequency compression hearing aid with new concepts is beneficial for severe-to-profound hearing impairments. (2) METHODS: Clinical trials of this hearing aid were conducted for 11 severe-to-profound hearing impaired listeners. These 11 wore the frequency compression hearing aid in their daily life and reported subjectively on its performance. Speech recognition tests with five listeners and audio-visual short sentence recognition tests with three listeners were also conducted. This hearing aid can separately adjust the fundamental frequency from the spectral envelope of input speech and can adjust frequency response by use of a post-processing digital filter. (3) RESULTS: Five listeners out of these 11 came to prefer this hearing aid in their daily life and are still wearing it. The results of the speech recognition tests show that the speech recognition scores were not improved for all listeners and the results of the audio-visual short sentence recognition tests do that the audio-visual recognition scores were improved for two listeners. (4) CONCLUSION: There were some severe-to-profound hearing impaired listeners who preferred the frequency compression hearing aid finally. It is also suggested that the benefits of this hearing aid may be evaluated correctly using not only speech but also visual materials.

Aged↗
PubMed2000

Bone-conducted evoked myogenic potentials from the sternocleidomastoid muscle.

The aim of this study was to show that bone-conducted clicks and short tone bursts (STBs) can evoke myogenic potentials from the sternocleidomastoid muscle (SCM) and that these responses are of vestibular origin. Evoked potential responses to bone-conducted auditory stimuli were recorded from the SCMs of 20 normal volunteers and from 12 patients with well-defined lesions of the middle or inner ear or the VIIIth cranial nerve. The subjects, who had various labyrinthine and retro-labyrinthine pathologies, included five patients with bilateral profound conductive hearing loss, two with bilateral acoustic neuroma post-total neurectomy and five with bilateral sensorineural hearing loss. Air- and bone-conducted evoked myogenic potentials in response to clicks and STBs were recorded with surface electrodes over each SCM of each subject. In normal subjects, bone- and air-conducted clicks and STBs evoked biphasic responses from the SCM ipsilateral to the stimulated ear. The bone-conducted clicks evoked short-latency vestibular-evoked myogenic potential (VEMP) responses only in young subjects or in subjects with conductive hearing loss. STBs evoked VEMPs with higher amplitude and better waveform morphology than clicks with the same acoustic intensity. Patients with total VIIIth cranial nerve neurectomy showed no responses to air- or bone-conducted click or STB stimuli. Clear VEMP responses were evoked from patients with conductive or sensorineural hearing loss. It is concluded that loud auditory stimuli delivered by bone- as well as air conduction can evoke myogenic potentials from the SCM. These responses seem to be of vestibular origin.

Acoustic Stimulation↗
PubMed2000

Long-term changes in middle latency response and evidence of retrograde degeneration in the medial geniculate body after auditory cortical ablation in cats.

Short- and long-term changes in the middle latency response (MLR) after bilateral ablation of the auditory cortices were studied in awake cats. The amplitude of the negative peak with a latency of about 15 ms (NA) decreased to 60% of the original value 1 week after ablation (short-term change). In the long term, i.e. 11-30 months, NA either decreased further (decreased group) or remained unchanged (non-decreased group). A histological study with light microscopy revealed degeneration of neurons in the ventral nucleus of the medial geniculate body (MGv) in the decreased group, whereas the neurons in this region were preserved in the non-decreased group. This study suggests that long-term changes in NA reflect retrograde degeneration in the MGv after auditory cortical ablation.

Animals↗
PubMed2000

Neuropathology of auditory agnosia following bilateral temporal lobe lesions: a case study.

Our patient was first diagnosed with auditory agnosia following his second cerebral vascular accident (CVA) in 1975 when he was 37 years old. Comprehensive follow-up examinations of auditory function were periodically conducted until his sudden death 15 years later. His brain was studied postmortem for neuropathology. Initial pure-tone audiometry revealed moderate sensorineural hearing loss in the right ear and mild sensorineural hearing loss in the left ear. However, repeated pure-tone audiometry revealed that thresholds became progressively poorer over time, bilaterally. Speech audiometry of both ears consistently revealed that the patient was unable to discriminate any monosyllabic words (i.e. speech intelligibility scores were 0%, bilaterally). In general, speech and hearing tests demonstrated that he could not comprehend spoken words, but could comprehend written commands and gestures. Postmortem neuropathological study of the left hemisphere revealed total defect and neuronal loss of the superior temporal gyrus, including Heschl's gyrus, and total gliosis of the medial geniculate body. In the right hemisphere, examination revealed subcortical necrosis, gliosis in the centre of the superior temporal gyrus and partial gliosis of the medial geniculate body. The pathological examination supports clinical results in which the patient's imperception of speech sounds, music and environmental sounds could be caused by progressive degeneration of bilateral medial geniculate bodies.

Adult↗
PubMed2000

Vestibular function in auditory neuropathy.

Auditory neuropathy is characterized by mild-to-moderate pure-tone hearing loss, poor speech discrimination out of proportion with this loss, absent or abnormal auditory brainstem responses and normal outer hair cell function as measured by otoacoustic emissions and cochlear microphonics. We followed three patients in our clinic whom we classified as auditory neuropathy patients. These patients also complained of balance disorders and we report our auditory and vestibular system analyses of these patients. The data presented herein include results of audiometric tests (serial pure-tone audiometry and speech discrimination tests), otoacoustic emissions, auditory-evoked brainstem responses and vestibular function tests (clinical tests of balance, electronystagmography, damped rotation tests and vestibular-evoked myogenic potentials). In all patients, pure-tone audiometry revealed mild-to-moderate sensorineural hearing loss, markedly poor speech discrimination scores and absent auditory-evoked brainstem responses, all in the presence of normal otoacoustic emissions. Balance tests (caloric tests and damped rotation test) were abnormal. Saccades, smooth pursuit eye movements and optokinetic nystagmus were normal in all patients. Neurological and motor system evaluations were normal in all patients. These three auditory neuropathy patients manifest a disorder of cochlear nerve function in the presence of normal outer hair cell activity. They additionally manifest a disorder of the vestibular nerve and its end organs. We conclude that, in patients with isolated auditory neuropathy, the vestibular branch of the VIIIth cranial nerve and its innervated structures may also be affected. We suggest the use of the term "cochlear neuropathy" to characterize those patients with involvement of only the auditory branch of the VIIIth cranial nerve and its innervation.

Aged↗
PubMed2000

Long-term follow-up of auditory agnosia as a sequel of herpes encephalitis in a child.

We report a pediatric patient with auditory agnosia as a sequel of herpes encephalitis. His early development was completely normal. He uttered three words at 12 months old. Disease onset was 1 year and 2 months of age. He was discharged from the hospital seemingly with no sequel; however, he could not recover his intelligible words even at age 2 years. He was diagnosed as having auditory agnosia caused by bilateral temporal lobe injury. We began to train him at once, individually and intensively. Adult patients with pure auditory agnosia followed by two episodes of temporal lobe infarction have impairment in central hearing but not inner language. Therefore, they can communicate by reading and writing. Moreover, impairment in hearing is not always severe and is often transient. However, despite long-term (more than 15 years) energetic education and almost normal intellectual ability (Performance IQ of Wechsler Intelligence Scale for Children-Revised was 91), our patient's language ability was extremely poor. Cerebral plasticity could not work fully on our patient, whose bilateral temporal lobe was severely injured in early childhood. The establishment of a systematic training method in such patients is an urgent objective in this field.

Adolescent↗