Biomedical subjects

Kimitaka Kaga

Publications and source records attributed to Kimitaka Kaga.

85 records · Page 5Linked to original sources

PubMed2002

Distortion evoked otoacoustic emission using GSI 70 analyzer for neonatal screening.

OBJECTIVE: Following the recommendation of the United State National Institute of Health Consensus Conference in 1993, otoacoustic emissions (OAE) are now used internationally for hearing screening. The GSI 70 OAE screener provides the means for carrying out OAE recordings within a short period of time and includes an automatic evaluation of results. The aim of this study was to determine the reliability of recordings in comparison with available standards in brainstem audiometry. METHOD: OAE recorded in 29 hearing-impaired suspected infants and young children (aged 1 months-7 years old) in order to compare the result of the GSI 70 screener with the result of ABR. This study was conducted in the outpatient clinic of the Tokyo University Hospital. RESULT: Our study showed that the GSI 70 screener has higher false negative rate compared with ABR results (P<0.01). Consequently, an OAE measuring method, is also provides high sensitivity and easy to use. However, there was no trend toward increased refer rates with increased age. CONCLUSION: Our findings show that the GSI 70 screener can meet the demands of systematic hearing screening in infants and young children, although there is a tendency to miss cochlear impaired cases.

Audiometry, Evoked Response↗

PubMed2002

Hair cell development in vivo and in vitro: analysis by using a monoclonal antibody specific to hair cells in the chick inner ear.

The purpose of this study was to establish a hair cell-specific marker and a convenient explant culture system for developing chick otocysts to facilitate in vivo and in vitro studies focusing on hair cell genesis in the inner ear. To achieve this, a hair cell-specific monoclonal antibody, 2A7, was generated by immunizing chick inner ear tissues to a mouse. Through the use of immunofluorescence and immunoelectron microscopy, it was shown that 2A7 immunoreactivity (2A7-IR) was primarily restricted to the apical region of inner ear hair cells, including stereocilia, kinocilia, apical membrane amongst the extending cilia, and superficial layer of the cuticular plate. Although the 2A7 antibody immunolabeled basically all of the hair cells in the posthatch chick inner ear, two different patterns of 2A7-IR were observed; hair cells located in the striolar region of the utricular macula, which consist of two distinct cell types identifiable on the basis of the type of nerve ending, Type I and II hair cells, showed labeling restricted to the basal end of the hair bundles. On the other hand, hair cells in the extrastriolar region, which are exclusively of Type II, showed labeling extending over virtually the entire length of the bundles. These findings raised the possibility that chick vestibular Type II hair cells, characterized by their bouton-type afferent nerve endings, can be divided into two subpopulations. Analysis of developing inner ear by using the 2A7 antibody revealed that this antibody also recognizes newly differentiated immature hair cells. Thus, the 2A7 antibody is able to recognize both immature and mature hair cells in vivo. The developmental potential of embryonic otocysts in vitro was then assessed by using explant cultures as a model. In this study, conventional otocyst explant cultures were modified by placing the tissues on floating polycarbonate filters on culture media, thereby allowing the easy manipulation of explants. In these cultures, 2A7-positive hair cells were differentiated from dividing precursor cells in vitro on the same schedule as in vivo. Furthermore, it was found that hair cells with both types of 2A7-IR were generated in culture as in vivo, indicating that a maturational process of hair cells also occurred. All these results as presented here suggest that the 2A7 monoclonal antibody as a hair cell-specific marker together with the culture system could be a potential tool in analysis of mechanisms underlying hair cell development.

Animals↗

PubMed2002

Postlingual collapse of language and its recovery after cochlear implantation.

A 6-year-old boy lost his normally-developed language ability within 2 months after bilateral sudden peripheral deafness. The boy became non-communicative with others, restless with frequent meaningless bursts of shouts (communication skills equivalent to 9-11 months of language development: a rapid breakdown of language). Since conservative methods were ineffective, cochlear implantation was performed. A surprising success was observed: he regained the language retracing the normal developmental stages and caught up with his contemporaries in 2 years. Behavioral improvement paralleled his language development. This case (1) provides insights into the brain function with respect to language acquisition, in relation to the plasticity during the 'critical period' of language learning, (2) reveals the close relationship between language development and behavior, and (3) suggests the predominance of auditory stimulation in learning language.

Child↗

PubMed2002

Effect of noise exposure on blood-labyrinth barrier in guinea pigs.

The influence of noise exposure on the endothelial transport system in the cochlea was investigated using cationic polyethyleneimine (PEI), since systemically administered PEI passes through the capillary endothelial cell and attaches to basal lamina (BL) anionic sites in the cochlea. Under general anesthesia, all guinea pigs were administered an intravenous injection of 0.5% PEI. Thirty minutes later, five animals were exposed to noise (10 kHz, broad band noise, 105 dB SPL) for 30 min, via speakers inserted into the external auditory canal. The remaining five animals (controls) were left without noise exposure for 1 h following PEI injection. All guinea pigs were then immediately sacrificed, and the bony labyrinths were removed. PEI distribution on the BL was assessed in the stria vascularis, spiral ligament, basilar membrane, spiral limbus and Reissner's membrane throughout the cochlea with transmission electron microscopy. Compared to control animals, PEI distribution in the noise-exposed animals was significantly increased in the strial vessels of the basal and second turns and in Reissner's membrane of all turns. In the spiral ligament, basilar membrane and spiral limbus, no significant difference in PEI distribution was observed between the control and noise-exposed animals. These findings indicate that noise exposure increases macromolecular transport in the stria vascularis but not in the spiral ligament, spiral limbus and basilar membrane and that systemically administered macromolecules are more readily transported to Reissner's membrane by noise exposure.

Animals↗

PubMed2002

The otolithic organ as a receptor of vestibular hearing revealed by vestibular-evoked myogenic potentials in patients with inner ear anomalies.

The human vestibule has preserved an ancestral sound sensitivity and it has been suggested that a reflex could originate from this property underlying cervical muscle micro-contractions secondary to strong acoustic stimulation. Previous studies have established that an early component of loud sound-evoked myogenic potentials from the sternocleidomastoid muscle originate in the vestibule. This is based on findings that the response can still be obtained from patients with complete loss of cochlear and vestibular (semi-circular canal) function. Our data confirm, in a more direct way, a saccular origin of this short-latency acoustic response and verifies that a saccular acoustic response persists in the human ear. The contribution of this response to the perception of loud sounds is discussed. It is concluded that vestibular response to sound might be used to assist in the rehabilitation of deafness.

Adolescent↗

PubMed2002

Progressive hearing loss in an infant in a neonatal intensive care unit as revealed by auditory evoked brainstem responses.

We herein report a case of a 14-month-old infant who revealed a progressive hearing loss by repeated auditory evoked brainstem responses (ABR) during his 1 year stay in the neonatal intensive care unit (NICU). He was born prematurely with asphyxia, hyperbilirubinemia and respiratory distress. During his 1 year stay in the NICU he was under constant mechanical ventilation. Repeated ABRs over this year initially showed normal waves but subsequently demonstrated progressive hearing impairment (HI) leading finally to no responses. Possible causes of this progressive deafness (PF) include the multiple problems of asphyxia, hyperbilirubinemia and pulmonary disorders.

Deafness↗

PubMed2002

Auditory behaviors and auditory brainstem responses of infants with hypogenesis of cerebral hemispheres.

Three infants with an almost complete absence of the cerebral hemispheres as a result of brain anomalies were studied both audiologically and neurologically. The brain anomalies were diagnosed by means of MRI and CT scans. Behavioral audiometry revealed reactions only to loud sound stimulations but auditory brainstem responses showed wave configurations and thresholds compatible with the ages of the infants. There were significant differences in the thresholds obtained by behavioral audiometry and auditory brainstem responses. It can be considered that these auditorily stimulated behavioral responses are evoked by auditory motor reflexes originating in the brainstem, but not by auditory perception.

Audiometry↗

PubMed2002

Direct application of keratinocyte growth factor, basic fibroblast growth factor and transforming growth factor-alpha during healing of tympanic membrane perforation in glucocorticoid-treated rats.

Peptide growth factors and cytokines modulate both normal and impaired wound healing. Topical application of growth factors in the form of ear drops may counteract impairment of wound healing in the tympanic membrane (TM). We applied keratinocyte growth factor (KGF), transforming growth factor (TGF)-alpha or basic fibroblast growth factor (bFGF) to the perforated TMs of rats in which healing impairment had been caused by systemic administration of a glucocorticoid. Histologic studies of the injured TM, including anti-5-bromo-2'-deoxyuridine immunohistochemistry, were performed on the third day after wounding. In the control ear, epidermal migration was markedly inhibited by glucocorticoid treatment and no hyperplasia was observed in any layer at the perforation edge. TMs treated with KGF showed marked hyperplasia in the epithelial layer at the perforation edge. In the bFGF- and TGF-alpha-treated groups, hyperplasia was observed in the epithelial and intermediate layers of the TM near the malleus handle and annulus, while no hyperplasia was seen in any layer at the perforation edge. Only KGF, therefore, improved epidermal migration in the TM, while all the growth factors tested induced hyperplasia in the TM.

Animals↗

PubMed2002

Total middle ear reconstructive surgery for the radicalized ear.

OBJECTIVE: To evaluate the efficacy of total middle ear reconstructive surgery (TMRS) for patients with open cavity problems. STUDY DESIGN: Retrospective study of patients treated between 1994 and 1997. SETTING: Tertiary care, referral medical center. PATIENTS: Fifty-nine consecutive patients (62 ears) with open cavity problems (draining ears) who underwent TMRS. MAIN OUTCOME MEASURES: Postoperative states of the ears and complications were evaluated in two groups, with and without persistent purulent otorrhea at the time of surgery. RESULTS: In the noninfected group, ears without otorrhea were maintained in 12 (100%) of 12 ears in the short term and 10 (83%) of 12 ears in the long term. In the infected group, the proportions were 40 (80%) of 50 ears and 35 (73%) of 48 ears, for the short and long terms, respectively. Hollowing and/or retraction of the reconstructed canal wall was observed in 1 (8%) of 12 ears of the noninfected group and in 15 (31%) of 48 ears of the infected group after long-term follow-up. Postoperative complications were encountered in 9 ears (14.5%) in the infected group only. CONCLUSIONS: Total middle ear reconstructive surgery is considered useful for the management of persistent discharge from radicalized cavities. It was found important to minimize infection at the time of surgery to achieve satisfactory results.

Adult↗

PubMed2002

Facial canal anatomy in patients with microtia: evaluation of the temporal bones with thin-section CT.

PURPOSE: To ascertain the location of the facial nerve in patients with microtia by using thin-section computed tomography (CT). MATERIALS AND METHODS: Thin-section CT was performed in 66 ears of patients with microtia (unilateral, n = 12; bilateral, n = 34) and mandibulofacial dysostosis (MFD, n = 20). Findings were compared with those in 22 ears with normal auricles (control group) by using the Dunnett two-sided t test. RESULTS: The facial nerve at the mastoid portion in patients with MFD was 2 mm more lateral and 3 mm more anterior than that in control subjects (P <.01). The same portion in patients with microtia was 3 mm more anterior than that in the control subjects (P <.01). The distance between the facial nerve and the most lateral point of the temporal bone in patients with MFD was 10 mm shorter and that in patients with bilateral microtia was 3 mm shorter than that in the control subjects (P <.01). CONCLUSION: The facial nerve in patients with microtia was not more lateral from the Bill bar (vertical crest) than that in control subjects. The facial nerve in patients with MFD was different from that in patients with microtia who had no other head anomalies.

Case-Control Studies↗

PubMed2002

Functional definitions of vocal fold geometry for laryngeal biomechanical modeling.

Precise geometric data on vocal fold dimensions are necessary for defining the vocal fold boundaries with respect to the laryngeal framework in physiological and biomechanical models of the larynx (eg, finite-element models). In the mid-membranous coronal section, vocal fold depth can be defined as the horizontal distance from the vocal fold medial surface to the thyroid cartilage, whereas vocal fold thickness can be defined as the vertical distance from the inferior border of the thyroarytenoid muscle to the vocal fold superior surface. Traditionally, such geometric data have been obtained from measurements made on histologic tissue sections. Unfortunately, it is very difficult to obtain reliable data by this method, unless the effects of sample preparation on vocal fold geometry are quantified. Significant tissue deformations are often induced by histologic processes such as fixation and dehydration, sometimes producing shrinkages as large as 30%. In this study, reliable geometric data of the canine vocal fold were obtained by the alternative method of quick-freezing for sample preparation, using liquid nitrogen. Coronal sections of quick-frozen larynges were thawed gradually in saline solution. Images of the mid-membranous coronal sections at various thawing stages were captured by a digital camera. Measurements of operationally defined vocal fold dimensions (depth and thickness) useful for biomechanical modeling were made with a graphics software package. The results showed that geometric changes of the vocal fold induced by freezing are likely reversed by thawing, such that the measurements made on thawed larynges are reliable approximations of the actual vocal fold dimensions.

Animals↗

PubMed2002

Comparison of duration of deafness and tumour invasion to the inner ear from metastatic tumours of the internal auditory canal: human temporal bone pathology.

Four cases (seven ears) of metastatic tumour of the internal auditory canal were studied. The histopathological findings confirmed that the inner ear invasion of the tumour follows a unique course, as reported in the literature. Relationship between duration of deafness and extent of tumour invasion in the inner ear is discussed. It is suggested that the deafness could occur via neural invasion or compression near the ductus spiralis foraminosus.

Adenocarcinoma↗

PubMed2002

[Selective intraarterial infusion chemotherapy using a combined MRI-angiography system for head and neck cancers].

We performed selective intraarterial infusion chemotherapy using a combined MRI-angiography system for head and neck cancers. In three patients, three or five infusions of CDDP (100 mg/body) were administered to the feeding arteries selectively. For the evaluation of drug distribution, MRI during arteriography through the infusion pump was performed before CDDP administration. When a distribution mismatch was found, arterial selection was attempted again under a mechanically unstable C-arm system, and further evaluation under an MR system was carried out. Thus, more ideal treatment could be provided. We consider MRI during arteriography to be useful in assessing for distribution during intraarterial chemotherapy.

Antineoplastic Agents↗