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Kimitaka Kaga

Publications and source records attributed to Kimitaka Kaga.

At least 73 records · Page 4Linked to original sources
PubMed2004

Actions of subtype-specific purinergic ligands on rat spiral ganglion neurons.

In a previous study we showed that, in rat spiral ganglion neurons (SGNs), the adenosine 5'-triphosphate (ATP)-evoked currents were a combination of the activation of ionotropic receptors (the first fast current) and the activation of metabotropic receptors which secondarily opened non-selective cation channels. These two conductances imply the involvement of different receptor subtypes. In the present study, we tested three subtype-specific purinergic ligands: alpha,beta-methylene ATP (a;pha,beta-meATP) for P2X receptors, uridine 5'-triphosphate (UTP) for P2Y receptors and 2'-3'-O-(4-benzoylbenzoyl) ATP (Bz-ATP) for P2Z (P2X(7)) receptors. Application of 100 microM alpha,beta-meATP did not trigger any significant change in membrane conductance, while the SGNs were responsive to ATP. Pressure application of UTP (100 microM, 1 s) evoked an inward current averaging 344+/-169 pA at a holding potential of -50 mV. The conductance developed after a latency averaging 1.5+/-0.6 s, took 4-6 s to peak and reversed slowly within 15-30 s. The current-voltage curve reversed near 0 mV, suggesting a non-selective cation conductance, like the second component of the ATP conductance. Bz-ATP evoked an inward current which developed without latency, was sustained during ligand application and was rapidly inactivated at the end of application: the same characteristics as the first component of the ATP-evoked current. The Bz-ATP conductance reversed around -10 mV, indicating also a non-selective cation conductance. These results suggest that, in SGNs, ATP acts via two different receptor subtypes, ionotropic P2Z receptors and metabotropic P2Y receptors, and that these two receptor subtypes can assume different physiological roles.

Adenosine Triphosphate↗
PubMed2004

Overexpression of ErbB-2 protein in human middle ear cholesteatomas.

OBJECTIVE: The purpose of this study is to verify the hypothesis that ErbB-2 protein is overexpressed in human middle ear cholesteatomas and to elucidate the relationship between overexpression of ErbB-2 protein, cell proliferation, and apoptosis. STUDY DESIGN: Prospective review of 20 patients between 2001 and 2003 with middle ear cholesteatoma. METHODS: Middle ear cholesteatoma matrix and retroauricular skin were immunostained with anti-ErbB-2, Ki-67, and single-stranded DNA (ssDNA) antibody. The distribution of immunoreactivity to these antibodies and labeling indices were compared between cholesteatoma and retroauricular skin. RESULTS: In matrix of middle ear cholesteatoma, ErbB-2 and ssDNA were expressed in the keratinocytes of all layers and Ki-67 was expressed in the keratinocytes of the basal, lower spinous, and occasionally granular layer. In retroauricular skin, ErbB-2 and Ki-67 were expressed in the keratinocytes of the basal and occasionally lower spinous layer and ssDNA was expressed in the keratinocytes of all layers. Labeling indices against anti-ErbB-2, Ki-67, and ssDNA antibody were significantly greater in cholesteatoma as compared with retroauricular skin. CONCLUSIONS: In cases of cholesteatoma, ErbB-2 protein was overexpressed and cell proliferation and apoptosis of keratinocytes were accelerated. ErbB-2 protein could modulate terminal differentiation and apoptosis in the keratinocytes of all layers in cholesteatoma matrix and cell proliferation in the keratinocytes of the basal and lower spinous layer in normal skin.

Adolescent↗
PubMed2004

Elevated expression of cyclooxygenase-2 in adenocarcinoma of the parotid gland: insights into malignant transformation of pleomorphic adenoma.

Pleomorphic adenoma, the most common type of tumor of the parotid gland, may transform into a malignant tumor. In the current study, we investigated whether the expression of cyclooxygenase-2 (COX-2) is elevated in adenocarcinoma as compared to pleomorphic adenoma. Ten pleomorphic adenomas and 10 adenocarcinomas were examined. The tumor specimens were immunohistochemically stained with antibodies against COX-2 and Ki-67. The labeling indices of COX-2 in pleomorphic adenoma and adenocarcinoma were 6.0% +/- 4.1% and 16.1% +/- 4.6%, respectively, and those of Ki-67 in pleomorphic adenoma and adenocarcinoma were 0.77% +/- 0.62% and 6.9% +/- 6.6%, respectively. The labeling indices of both COX-2 and Ki-67 were significantly greater (p < .001) in adenocarcinoma than in pleomorphic adenoma. Together with the biological effects of COX-2, these results suggest that overexpression of COX-2 plays a crucial role in the pathogenesis of malignant transformation of pleomorphic adenoma in the parotid gland.

Adenocarcinoma↗
PubMed2004

[Presbycusis].

Explore the source record for details and available documents.

Aged↗
PubMed2004

Middle-latency auditory-evoked magnetic fields in patients with auditory cortex lesions.

OBJECTIVE: To demonstrate the influence of auditory cortex lesions on auditory middle-latency responses (AMLRs) and middle-latency auditory-evoked magnetic fields (MLAEFs) in humans. MATERIAL AND METHODS: A total of 15 normal subjects, 9 patients with left auditory cortex lesions and 1 patient with a right auditory cortex lesion were studied. MLAEFs were recorded from each hemisphere of the brain in a magnetically shielded room using a 37-channel SQUID gradiometer. Simultaneously, AMLRs were recorded from the scalp at the vertex, C3 and C4. Tone bursts were used as auditory stimuli. RESULTS: Pam responses of the MLAEF, which are typically evoked in the latency range of the Pa of the AMLR, and are localized at the auditory cortex as dipoles, were impaired or abolished over the left auditory cortex lesion in the patients with left-hemisphere lesions, but the Pa of the AMLR persisted. CONCLUSION: The main generator of the Pam in MLAEF was demonstrated to be the auditory cortex. The results also show that the Pa of the AMLR is evoked only partly from the auditory cortex.

Acoustic Stimulation↗
PubMed2003

Adenoviral vector gene delivery via the round window membrane in guinea pigs.

We have found that damage from a local anesthetic solution containing phenol permitted beta-galactosidase (beta-gal) gene delivery to the guinea pig inner ear via the round window membrane (RWM). RWM damage was evident as degeneration of the outer epithelium. After adenovirus lacZ vector was applied to the damaged RWM, immunohistochemistry showed strong beta-gal expression in the RWM, mesothelial cells, organ of Corti, spiral limbus, spiral ligament and spiral ganglion. In the vestibular labyrinth, expression was seen in the sensory and supporting cells, transitional cells, and the dark-cell area. Thus, adenovirus can transfect a variety of inner ear cells in the guinea pig through a damaged RWM.

Adenoviridae↗
PubMed2003

Auditory lexical-semantic processing impairments in aphasic patients reflected in event-related potentials (N400).

OBJECTIVE: Event-related potentials (ERPs) and response latencies were recorded from aphasic subjects with auditory language processing impairments and age-matched normal controls, while performing a lexical-semantic evaluation task, aiming at clarifying whether ERPs could be a reliable measure for indicating language impairments in aphasic patients. METHODS: The stimuli were 50 pairs of spoken words (prime word-target word): 25 pairs, which were semantically and/or associatively related to each other, and 25 pairs which were not. The subjects pressed a switch in response to the presentation of target words semantically related to the prime words. The ERP component analyzed in this study was N400. RESULTS: With the performances, the response latencies were longer in the aphasic subjects than in the normal controls. With the ERPs, onset latencies of N400 were shifted behind in the aphasic patients compared to the normal controls. For the aphasic patients, there were correlations between the size of N400 and performances in auditory comprehension evaluated in the aphasia test. CONCLUSION: The conclusions drawn from the results are that not only response latencies in the lexical-semantic judgement task, but also N400 effects, may be a reliable clinical measure of the severity of even mild lexical-semantic impairments in aphasic patients.

Acoustic Stimulation↗
PubMed2003

Aplasia of zygomatic arch and dislocation of temporomandibular joint capsule in Treacher-Collins syndrome: three-dimensional reconstruction of computed tomographic scans.

Seven patients with Treacher-Collins syndrome were studied. All of patients were children or teenagers. Helical CT scanner (Toshiba) was used to reconstruct zygomatic arch and temporomandibular joint capsule on lateral aspect of temporal bone in five patients of microtia and atresia of both ears and two patients of narrow ear canals of both ears without microtia.Three-dimensional reconstructions of computed tomography on lateral aspect of temporal bone demonstrated various congenital abnormality including aplasia of zygomatic arch in seven patients and dislocation of temporomandibular joint capsule in seven patients.

Adolescent↗
PubMed2003

Binaural interaction of bone-conducted auditory brainstem responses in children with congenital atresia of the external auditory canal.

Bilateral bone-conducted auditory brainstem responses (BC-ABRs) were recorded in children with atresia of the external auditory canal bilaterally (AECB) in order to compare the response characteristics to normal hearing adults. The binaural interaction component (BIC) of the ABR occurs when the sum of the monaural-evoked ABR amplitudes are different in amplitude when compared to the binaural-evoked ABR amplitude. Previous electrophysiological work from our lab has shown that children with AECB lateralize bone-conducted (BC) sound. Furthermore, we have found in normal-hearing adults that BICs exist using BC clicks. In adults, BC-BIC occurred in the latency region corresponding to waves IV-VI, whereas for children with AECB corresponding peak latencies occurred earlier. Same as normal-hearing adults, BC-ABR IV-V complex peak amplitudes for sum of the BC-monaural right and BC-monaural left ears were different from binaural response amplitude. Individual peak latencies were similar in children with AECB when compared to normal-hearing adults except for shorter latencies for BIC. These results indicate that: (1) BC-BI is present in children with AECB as well as normal-hearing adults; (2) the gross response properties of BIC are similar in children with AECB and normal-hearing adults; (3) fitting of a bilateral BC hearing aid might be a feasible method to optimize binaural hearing and sound lateralization.

Adolescent↗
PubMed2003

Assessment of total middle ear reconstruction by patient survey correlated with clinical findings.

OBJECTIVE: Our objective was to assess, by patient survey and clinical examination, the results of correctional total middle ear reconstruction of problematic mastoid cavities following radical or modified radical mastoidectomy. SETTING: This study was performed in an academic tertiary referral center. PATIENTS: The study consisted of a retrospective survey, using the modified hearing satisfaction scale, of 50 patients, who had undergone total middle ear reconstruction of their problematic mastoid cavities. The survey results were correlated with their postoperative clinical findings. RESULTS: Postoperatively, 98% of these patients expressed satisfaction in terms of improvement of their preexisting otorrhea (median of 4.32 satisfied), 65% were satisfied with their hearing and 85% were satisfied with the overall of this operation. The survey results had a good correlation with the audiometric findings and the clinical findings, i.e. the surgery resulted in a dry ear in all 50 patients and 51% of these patients showed hearing improvement of more than 5 dBHL. CONCLUSIONS: This study indicates that most patients were satisfied with the outcomes of this operation. The patients' point of view and the postoperative clinical data both indicate that total middle ear reconstruction is an excellent procedure for correcting problematic mastoid cavities following a radical or modified radical mastoidectomy. The hearing satisfaction scale is a useful instrument for assessing patient satisfaction following this surgical procedure.

Activities of Daily Living↗
PubMed2003

Foreign bodies in the aerodigestive tract in pediatric patients.

OBJECTIVE: To investigate pediatric foreign body cases in the aerodigestive tract, and to elucidate the characteristic problems in Japan. METHODS: A total of 310 pediatric patients (age 15 or below), gathered from two medical university hospitals (University of Tokyo and Jichi Medical School), were included in this study. Data were collected by retrospective chart review and were statistically analyzed. RESULTS: Two-year-olds were the most common patients, and the range from age 1 to age 4 included 67.7% of all the patients. The most involved sites were the nose (39.4%) and the pharynx (38.4%), followed by the esophagus (12.9%) and the trachea-bronchi (6.5%). Fish bones and toys were the representative foreign bodies (30.7 and 13.6%, respectively). Other foreign bodies often encountered included coins, food, candy, peanuts and nuts, and batteries. The type of foreign body was closely related to the site in which foreign bodies were lodged: 77.3% of foreign bodies in the pharynx were fish bones, and toys were the most common impacted foreign body in the nose. In the esophagus, representative impacted foreign bodies were coins (35.7%), but disk-type battery ingestion has been increasing in recent years. Although most foreign bodies in the esophagus were safely removed, one case of a disk-type battery had a serious sequela. In the trachea-bronchi, peanuts, food, cotton, and coins were impacted. A rigid bronchoscope was basically used to remove foreign bodies, but in some cases, a fine flexible endoscope, with a channel for fiber forceps, was useful, because it could be inserted into narrow bronchi. Advance of a flexible endoscope will make it an excellent tool for diagnosis and management of the trachea-bronchial foreign body. CONCLUSIONS: Fish bones in the pharynx, which were closely related to Japanese eating habits, and toys in the nose, were the typical foreign bodies encountered in this study. In the esophagus, an increased incidence of disk-type battery ingestion has become a serious problem in recent years. Since prevention is the most essential way to manage foreign body cases, feedback from studies to public education should be encouraged.

Adolescent↗
PubMed2003

Auditory agnosia in children after herpes encephalitis.

Four pediatric patients whose bilateral auditory cortices were damaged by herpes encephalitis at an early age were studied. Their brain CT and MRI scans demonstrated common bilateral lesions of the auditory cortices. Their auditory perception was investigated by means of behavioral and objective hearing tests and auditory perception tests. All four patients showed mild or moderate hearing loss in the behavioral hearing test and normal auditory brainstem responses but did not manifest total deafness. Moreover, perception tests involving speech, environmental sounds and music demonstrated that most auditory perception ability had been lost in all patients. On reaching school age, the patients were enrolled in schools for the deaf or special schools for handicapped children.

Agnosia↗
PubMed2003

Negamycin restores dystrophin expression in skeletal and cardiac muscles of mdx mice.

The ability of aminoglycoside antibiotics to promote read-through of nonsense mutations has attracted interest in these drugs as potential therapeutic agents in genetic diseases. However, the toxicity of aminoglycoside antibiotics may result in severe side effects during long-term treatment. In this paper, we report that negamycin, a dipeptide antibiotic, also restores dystrophin expression in skeletal and cardiac muscles of the mdx mouse, an animal model of Duchenne muscular dystrophy (DMD) with a nonsense mutation in the dystrophin gene, and in cultured mdx myotubes. Dystrophin expression was confirmed by immunohistochemistry and immunoblotting. We also compared the toxicity of negamycin and gentamicin, and found negamycin to be less toxic. Furthermore, we demonstrate that negamycin binds to a partial sequence of the eukaryotic rRNA-decoding A-site. We conclude that negamycin is a promising new therapeutic candidate for DMD and other genetic diseases caused by nonsense mutations.

Amino Acids, Diamino↗
PubMed2003

Difference in facial canal anatomy in terms of severity of microtia and deformity of middle ear in patients with microtia.

OBJECTIVE: To study the difference in the facial canal anatomy in terms of the severity of microtia and deformity of the middle ear in patients with microtia using high-resolution computed tomography (HRCT). STUDY DESIGN: Forty-six ears with microtia were examined by HRCT. These ears were graded based on two systems of classification and scoring, respectively. The HRCT findings of each group were compared with those of other groups by multiple comparison using the Tukey honestly significant difference test. METHODS: Forty-six ears with microtia (unilateral microtia, n = 12; bilateral microtia, n = 34) were examined by HRCT. These ears were graded based on two systems of classification and scoring, respectively. The HRCT findings and age distribution of each group were compared with those of other groups by multiple comparison using the Tukey honestly significant difference test. RESULTS: The mastoid portion of the facial nerve was 3 mm more anteriorly displaced in patients with grades II and III microtia than in those with grade I microtia (P <.01). From the scoring system that was used, the course of the facial nerve was not significantly different between patients with a score of 5 points or less and those with a score of 6 points or more. CONCLUSION: The mastoid portion of the facial nerve in patients with grades II and III microtia would be more anteriorly displaced because of hypoplasia of the second genu.

Child↗
PubMed2003

Use of cartilage plate as tympanic membrane in total middle ear reconstructive surgery for infected radicalized ear.

OBJECTIVE: To evaluate the usefulness of cartilage plates as tympanic membranes combined with total middle ear reconstructive surgery for radicalized ears. STUDY DESIGN: Retrospective study between 1994 and 1999. SETTING: Tertiary care referral medical center. PATIENTS: Seven patients had seven ears with severe chronic otorrhea after radical mastoidectomy. All patients had severe to profound sensorineural hearing loss and expected a trouble-free ear rather than improved hearing after surgery. Patients were followed up for 4 years postoperatively. METHODS: After the middle ear space was cleaned, the tympanic membrane was reconstructed using a plate prepared from the tragal cartilage. The major part of the posterior wall was reconstructed using a conchal cartilage plate. Cortical bone segments were inserted to support the cartilage plate. RESULTS: Preoperatively, cultures of ear discharge were positive for various bacteria. Recovery with dry eardrums was noted in six patients, and one patient showed minimal erosion. No postoperative complications were encountered, but the hearing threshold did not improve postoperatively. CONCLUSIONS: Total middle ear reconstructive surgery is suitable for patients with chronic otorrhea complicating radical mastoidectomy. The use of cartilage plates seems to be clinically appropriate, particularly for patients with severe infection who expect a trouble-free ear rather than hearing gain after surgery.

Adult↗
PubMed2003

Microelectrode array on folding polyimide ribbon for epidural mapping of functional evoked potentials.

This paper describes a flexible polyimide microelectrode ribbon with a bending structure for epidural recording. Bending the ribbon establishes good electro-mechanical contact of the electrodes to the cortex. Impedance spectroscopy and noise measurements in vitro were used to characterize the electrodes. Our in vivo experiments then successfully achieved synchronized neuronal activity and evoked potential patterns useful for understanding brain function and for finding cortical function.

Action Potentials↗
PubMed2002

Auditory brainstem responses and usefulness of hearing aids in hearing impaired children with Cornelia de Lange syndrome.

OBJECTIVE: To examine auditory brainstem evoked responses (ABRs) of children with Cornelia de Lange syndrome (CDLS) to evaluate hearing and the utility of hearing aids in hearing impaired cases. SUBJECTS AND METHODS: Thirteen Japanese infants and children with CDLS were studied. Behavioral observation audiometry and ABR were used to evaluate hearing. RESULT: Four different ABR patterns at 85 dB clicks were observed: no response in either ear (6 patients); clear ABRs in both ears (2 patients); no response in one ear but ABRs recorded in the other ear (3 patients); and no peaks after wave III in one ear and ABRs recorded in the other ear (2 patients). However, in 2 patients with no response in either ear at the first measurement, ABRs were recorded in one ear within 2 years. Three out of 13 patients exhibited better responses to sound through the use of hearing aids and auditory training. CONCLUSIONS: The fitting of hearing aids and early consistent training have a significant effect on auditory development in CDLS children in terms of making them aware of sound localization and the different types of environmental sound.

Audiometry↗