Biomedical subjects

Kimitaka Kaga

Publications and source records attributed to Kimitaka Kaga.

At least 19 recordsLinked to original sources

PubMed2007

Influence of chronic middle ear diseases on gustatory function: an electrogustometric study.

OBJECTIVE: We aimed to quantitatively determine whether middle ear inflammation associated with unilateral chronic otitis media (COM), cholesteatoma, or otosclerosis affects gustatory function. STUDY DESIGN: Prospective study. SETTING: University Hospital, Department of Otolaryngology. PATIENTS: Forty-two patients had unilateral COM (22 men, 20 women; mean age, 54.2 yr), 57 had unilateral cholesteatoma (35 men, 22 women; mean age, 42.1 yr), and 19 had unilateral otosclerosis (10 men, 9 women; mean age, 49.3 yr). MAIN OUTCOME MEASURES: Patients underwent taste testing using electrogustometry (EGM) and sensation thresholds were compared in the affected and unaffected ears among groups and between affected and unaffected ears in each group. RESULTS: Patients with COM and cholesteatoma exhibited an increase in taste threshold in the affected ears compared to the unaffected ears (p < 0.05), whereas otosclerosis patients did not. The extent of the increase of the sensation thresholds in the affected ears was very similar between patients with COM and those with cholesteatoma (p = 0.548). CONCLUSION: Our EGM study showed that cholesteatoma and chronic middle ear inflammation affected gustatory function to a similar degree.

Adult↗

PubMed2006

Study of nasopharyngeal bacterial flora. Second report. Variations in nasopharyngeal bacterial flora in children aged 6 years or younger when administered antimicrobial agents. Part 1.

In our first report, we investigated nasopharyngeal bacterial flora related to penicillin-resistant Streptococcus pneumoniae (PRSP) and beta-lactamase-negative ampicillin-resistant Haemophilus influenzae (BLNAR) and their relation to acute upper respiratory tract infection (AURTI). This report analyzes the results of a study of nasopharyngeal bacterial flora before the administration of antimicrobial agents in 172 AURTI patients aged 6 years or younger. In addition to Gram staining, microscopic observation, and culturing, a polymerase chain reaction (PCR) method was used to identify PRSP (gPRSP) and BLNAR (gBLNAR) drug-resistant genes. Of the patients analyzed, 90% had acute otitis media (AOM) and were aged 2 years or younger. The antimicrobial agents administered were amoxicillin (34%), clavulanic acid/amoxicillin (11%), cefditren pivoxil (CDTR-PI) (43%), and others (12%). This was particularly true for patients administered CDTR-PI, among whom there were many who had already suffered one or more episodes of AOM by the age of 1 year or younger, and many in which gPRSP were detected (P < 0.01). There was a significant relation between the degree of nasopharyngeal inflammation indicated by leukocyte infiltration images and the amount of S. pneumoniae and H. influenzae detected, which are the main pathogenic bacteria causing AOM (P < 0.01). In addition to leukocyte infiltration images, there were cases in which shedding of ciliated cells was observed and/or giant monocytic cells. Both nasopharyngeal leukocyte infiltration images and/or shed cell findings observed in infant AURTI cases are important indices for the prompt detection of gPRSP and/or gBLNAR and appropriate doses of antimicrobial agents.

Age Factors↗

PubMed2006

Study of nasopharyngeal bacterial flora. Second report. Variations in nasopharyngeal bacterial flora in children aged 6 years or younger when administered antimicrobial agents. Part 2.

This report focuses on changes in the nasopharyngeal bacterial flora before and after administration of antimicrobial agents in 172 cases of acute upper respiratory infection in patients aged 6 years or younger. The antimicrobial agents administered were amoxicillin (AMPC) (34%), clavulanic acid/amoxicillin compound (11%), cefditren pivoxil (CDTR-PI) (43%), and others (12%). Changes in nasopharyngeal bacterial flora were investigated with reexaminations conducted after 2-5 days (day 2-5 subgroup), 6-10 days (day 6-10 subgroup), and 11 days and thereafter. There was a significant reduction in the Streptococcus pneumoniae detected in the group administered AMPC (AMPC group) in the day 2-5 subgroup and the day 6-10 subgroup. There was also a significant decrease in H. influenzae in the group administered CDTR-PI (CDTR-PI group) in the day 2-5 subgroup. From this it was inferred that for the most part significant changes in infectious nasopharyngeal bacteria occurred in the day 2-5 subgroups. However, a significant improvement in the degree of inflammation, as indicated by leukocyte infiltration images for the AMPC group, was observed in the day 2-5 subgroup, and for the CDTR-PI group in the day 6-10 subgroup. On the other hand, in both the antimicrobial agent groups, S. pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis were newly detected at reexamination. Furthermore, a difference in the incidence of these bacteria was observed between the 2 antimicrobial agent groups. It was suggested that such phenomena related to the survival of resistant strains or a recurrence otitis media.

Anti-Infective Agents↗

PubMed2006

The effectiveness of wedge shoes in patients with insufficient vestibular compensation.

OBJECTIVES: Patients who fail to achieve sufficient vestibular compensation after acute vestibular deafferentation show a tendency to deviate toward the affected side. This study evaluated the effectiveness of wedge shoes specially manufactured with a 4mm inclination on the affected side to patients with chronic vestibular insufficiency. METHODS: Subjects comprised 13 patients with chronic vestibular insufficiency for >6 months after acute unilateral vestibular dysfunction and 9 healthy volunteers. Subjects underwent vestibular tests wearing wedge shoes and regular shoes. Differences in results were compared. RESULTS: Patients showed significant improvements in the straight gait test (p<0.01), Unterberger-Fukuda stepping test (p<0.01) and posturography test (p=0.015) when wearing wedge shoes compared with wearing regular shoes. CONCLUSION: Our results suggested that raising the lateral sole of shoes on the affected side could effectively ameliorate the effects of chronic vestibular insufficiency.

Adult↗

PubMed2006

Age-related changes in cell density and the proliferation rate of olfactory ensheathing cells in the lamina propria of postnatal mouse olfactory mucosa.

We investigated age-related changes in the distribution and proliferation of olfactory ensheathing cells (OECs) in postnatal mouse olfactory mucosa. In contrast to reported data on other glial cell types in the peripheral and central nervous systems, OEC cell density in the olfactory nerve bundles in the lamina propria remained almost constant from 10 days through 16 months of age. Electron microscopy of the nerve bundles revealed that axon packing density also was constant during that period. These findings suggest that the ratio of the number of OECs to the unit length of the olfactory neuron axons ensheathed by them does not change markedly throughout the lifetime of mice in an undisturbed condition. By contrast, OEC proliferative density decreased rapidly in the 10-day to 1-month-old period, showing a significant difference, and for the rest of life remained at low level, similar to previous values reported for other glial cell types.

Aging↗

PubMed2006

A magnetoencephalographic study of Japanese vowel processing.

Magnetic brain responses were recorded to clarify the cortical representation of vowel processing in Japanese. We investigated the peak latencies and equivalent current dipoles of the auditory N1m responses to the Japanese vowels [a], [i], [o], and [u]. In intraindividual analyses for a single participant, well-replicated results for the dipole parameters supported the existence of phoneme-specific cortical maps for vowels. In the interindividual analyses for the eight participants, [a] and [i] elicited significantly earlier N1m responses than [u], and the dipole for [i] was more posteriorly oriented than [a] in the left hemisphere. The results of the current study suggest left hemispheric predominance in vowel processing and that factors associated with a different language system may modify the cortical map.

Acoustic Stimulation↗

PubMed2006

Neuromagnetic responses to binaural beat in human cerebral cortex.

The dichotic presentation of two sinusoids with a slight difference in frequency elicits subjective fluctuations called binaural beat (BB). BBs provide a classic example of binaural interaction considered to result from neural interaction in the central auditory pathway that receives input from both ears. To explore the cortical representation of the fluctuation of BB, we recorded magnetic fields evoked by slow BB of 4.00 or 6.66 Hz in nine normal subjects. The fields showed small amplitudes; however, they were strong enough to be distinguished from the noise accompanying the recordings. Spectral analyses of the magnetic fields recorded on single channels revealed that the responses evoked by BBs contained a specific spectral component of BB frequency, and the magnetic fields were confirmed to represent an auditory steady-state response (ASSR) to BB. The analyses of spatial distribution of BB-synchronized responses and minimum-norm current estimates revealed multiple BB ASSR sources in the parietal and frontal cortices in addition to the temporal areas, including auditory cortices. The phase of synchronized waveforms showed great variability, suggesting that BB ASSR does not represent changing interaural phase differences (IPD) per se, but instead it reflects a higher-order cognitive process corresponding to subjective fluctuations of BB. Our findings confirm that the activity of the human cerebral cortex can be synchronized with slow BB by using information on the IPD.

Acoustic Stimulation↗

PubMed2006

Comparative study of fixed time versus intensity trade and fixed intensity versus time trade tests in sound lateralization.

OBJECTIVE: In the perception of sound lateralization a sound source exists in the side that the sound reaches an ear earlier in time or louder in intensity than the other ear. It is an imaginary phenomenon where the direction of sound is lateralized by an interaural time difference (ITD) and an interaural intensity difference (IID) of sound by both ears. It is speculated from pathophysiological findings that ITD and IID are processed by different pathways, but it has been not yet proved which of them is predominant in sound lateralization. The time difference can be traded by the intensity difference (fixed time versus intensity trade), and vice versa (fixed intensity versus time trade). In order to investigate predominance in this trade, we measured possible differences in effects by ITD and IID using two opposite trade phenomena of time versus intensity trade and intensity versus time trade. METHODS: The fixed time versus intensity trade test for selected narrow-band noise was investigated in 30 subjects with normal hearing. Using headphones, the subjects were instructed to push the button when the sound bias generated by fixed ITD (4 dB, 6 dB, 8 dB, 10 dB, 12 dB, 14 dB, 16 dB, 18 dB, 20 dB) was traded by gradually increased IID. The plot figure with fixed ITD and required IID to trade was made. It was compared with similar fixed intensity versus time trade test in 12 subjects with normal hearing. The fixed ITD (200-600 micros) was traded by gradually increased IID and the plot figure was made. RESULTS: In fixed time versus intensity trade test, each fixed ITD could be traded with an average of 6 dB of IID. On the other hand, in fixed intensity versus time trade test, ITD required to trade fixed IID increased, in proportion to fixed IID increased. CONCLUSION: It is concluded that predominance exists. In fixed time versus intensity trade test, the uniform amount of IID is required to trade the different ITD. However, in the novel fixed intensity versus time trade test, the phenomenon was in completely different manner that ITD in proportion to the given IID is required to trade.

Acoustic Stimulation↗

PubMed2006

Better time-intensity trade revealed by bilateral giant magnetostrictive bone conduction.

Sound lateralization tests were performed to compare the magnet coil bone-conduction headphone with the giant magnetostrictive bone-conduction headphone using 18 healthy participants. Although, no significant difference between these bone-conduction headphones was obtained for the interaural time difference and interaural intensity difference, a significant difference was obtained for the time-intensity trade. This revealed that the difference between the headphones is apparent in the integration of the heterogeneous sensations of the time and intensity difference at the cognitive level, but no difference is apparent between the homogeneous sensations of the discrimination of interaural time difference or interaural intensity difference at the sensory level. It was concluded that the difference at the cognitive level indicates the better performance of the giant magnetostrictive headphone.

Acoustic Stimulation↗

PubMed2006

Study of upper respiratory tract bacterial flora: first report. Variations in upper respiratory tract bacterial flora in patients with acute upper respiratory tract infection and healthy subjects and variations by subject age.

With the appearance of penicillin-resistant Streptococcus pneumoniae, there has been increasing debate concerning antimicrobial treatments for acute upper respiratory tract infection (AURTI) and acute otitis media in children. This study compares the nasopharyngeal bacterial flora in patients with AURTI (AURTI group; 710 subjects) and healthy subjects (HS group; 380 subjects). The comparisons were made between subjects aged 6 years or younger (0-6 subgroup: 330 subjects), between 7 and 74 years (7-74 subgroup: 668 subjects), and 75 years and older (92 subjects), because the subjects were subgrouped as described above dependent on the maturity of the protective immunity. In the HS group 7-74 subgroup, viridans group streptococci, Staphylococcus aureus, coagulase-negative staphylococci, and Corynebacterium sp. with a detection rate of 10% or more were classified as normal nasal flora (NNF), and Streptococcus pyogenes, Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis were classified as drum cavity pathogens (DCP). In the 0-6 subgroup, although the detection rate for DCP bacteria in the AURTI group tended to be high, it did not reach a significant difference, whereas the detection rate for NNF bacteria was significantly lower. This trend was also observed to some degree in the other age subgroup. In the 0-6 subgroup, leukocyte infiltration observed with a microscope indicated the closest relationship between S. pneumoniae detection rate and detection quantity. These results suggest that in the 0-6 subgroup the tendency for patients with AURTI to have NNF bacteria as well as DCP bacteria should be taken into consideration.

Acute Disease↗

PubMed2006

Noninvasive system for evaluating allergen-induced nasal hypersensitivity in murine allergic rhinitis.

Until now there has been no method for physiologically evaluating nasal hypersensitivity in mice. Enhanced pause (Penh) has been used as an indicator that reflects changes in the lower airway. Recently, however, there is disagreement regarding the significance of the Penh system; this is because Penh is not essentially a physiological parameter, and it might not necessarily represent a change in the lower respiratory tract. The purpose of the present study is to investigate whether Penh could be applicable for analyzing nasal hypersensitivity in mice. BALB/c mice were sensitized with ovalbumin (OVA) through a combination of intraperitoneal injection and daily intranasal challenge in an awake condition. Penh was measured at each time point during sensitization, or a serial change in Penh value was followed after the final nasal challenge and the effect of treatment was assessed. Following sensitization and nasal challenge, the Penh value gradually increased and showed a significant difference on day 14. Changes in IgE, eosinophil infiltration into nasal mucosa, and OVA-induced symptoms all strongly correlated with the increase in Penh. On day 19, after OVA nasal provocation, Penh gradually increased and reached maximal values 25 min after the challenge. Pretreatment with dexamethasone or a histamine H1 blocker significantly suppressed this increase in Penh. We confirmed that intranasal OVA challenge did not induce bronchoconstriction by measuring airway resistance and bronchoalveolar lavage fluid, and through histological examination. These results clearly demonstrate that Penh could be a useful noninvasive indicator for studying nasal hypersensitivity.

Airway Resistance↗

PubMed2006

Vestibular-evoked myogenic potentials in cochlear implant children.

CONCLUSIONS: Our results suggest that the sacculi of most children with cochlear implants can easily be damaged, as shown by the absence of vestibular-evoked myogenic potentials (VEMPs) in response to click stimuli. Also, in most of the children, the vestibular nerve was seemingly not stimulated by the cochlear implant. These results suggest that electrical stimulation at the C level can stimulate the cochlear nerve; however, this stimulation did not spread to the vestibular nerve in our children. In some children with Mondini dysplasia or vestibulocochlear nerve abnormality, the vestibular nerve was stimulated when the cochlear implant device was on, because of a VEMP response to electrical stimulation. OBJECTIVE: To clarify the diagnostic value of VEMPs in cochlear implant patients. MATERIAL AND METHODS: The click-evoked myogenic potentials of 12 children who underwent cochlear implantation surgery were investigated. The latency and amplitude of the VEMP responses were measured. RESULTS: Before surgery, 6 of the 12 children showed normal VEMPs, 1 showed a decrease in the amplitude of VEMPs and five showed no VEMP response. After surgery, with the cochlear implant device off, 1 child showed a decreased VEMP and 11 showed no VEMPs. With the cochlear implant device on, four children showed VEMPs and eight did not.

Caloric Tests↗

PubMed2006

Bone-conducted auditory brainstem-evoked responses and skull vibratory velocity measurement in rats at frequencies of 0.5-30 kHz with a new giant magnetostrictive bone conduction transducer.

CONCLUSIONS: A new giant magnetostrictive bone conduction transducer (GMT) measuring 8 mm (length) by 2 mm (diameter) is capable of outputting sounds over a wider range of frequencies than conventional electromagnetic transducers (EMTs). The GMT can vibrate the rat skull about 3-100 times faster than the EMT, especially above 2 kHz. OBJECTIVES: Since the GMT can generate high sound quality and output sounds above 10 kHz, we investigated the width of the frequency response of the GMT and evaluated its mechanical performance. MATERIALS AND METHODS: We chose Wistar rats to estimate the GMT performance by measuring the bone-conducted ABR and the skull vibratory velocity because their hearing frequency range extends from 0.15 kHz to 67 kHz. We also measured the bone-conducted auditory brainstem responses (ABRs) and the skull vibratory velocity of rats with the EMT. Skull vibratory velocity was measured with a laser Doppler vibrometer (LDV). RESULTS: The skull vibratory velocity at the ABR threshold obtained with each transducer was within the -35 to -50 dB range (0 dB re 1 mm/s). When 1 Vpp was applied to each transducer, the GMT had a higher velocity at frequencies of 2-30 kHz, and the EMT at frequencies of 0.5-1 kHz.

Animals↗

PubMed2006

Evaluation of recovery from transient facial palsy following canalplasty and tympanoplasty for the treatment of congenital aural atresia.

OBJECTIVES: Canalplasty is a surgical procedure of the external auditory canal. In this study we examined anatomic risk factors for facial nerve injury in aural atresia surgery, in addition to facial nerve outcomes and the time course of recovery in patients with facial nerve palsy following atresia surgery. METHODS: Transient facial palsy was observed immediately after surgery in 6 of 99 ears (6 of 87 patients) after canalplasty and tympanoplasty for the treatment of congenital aural atresia. We assessed the course of recovery and mean scores using Jahrsdoerfer's grading system. RESULTS: The rate of absence of the stapes and the rate of presence of positional anomalies of the facial nerve were significantly higher among cases with facial palsy, and Jahrsdoerfer total scores were significantly lower among cases with facial palsy. The mean recovery time in 5 cases with a minimum electroneurography value of 0% was 16.2 weeks (range, 14 to 18 weeks). No trends during recovery were detected for the nerve excitability test and R1 components of the blink reflex. CONCLUSIONS: The anatomic conditions that cause a predisposition to transient facial palsy include absence of the stapes and the presence of positional anomalies of the facial nerve. Although some patients displayed transient facial palsy after surgery, all patients fully recovered. Mechanisms of facial nerve injury are proposed.

Adolescent↗

PubMed2006

The toothbrush: a rare but potentially life-threatening cause of penetrating oropharyngeal trauma in children.

We present the case of a 10-year-old girl with pharyngeal injury caused by a toothbrush, the snapped head of which lodged in her upper oropharyngeal wall. Initial examination of the oral cavity did not reveal bleeding, a foreign body, or a wound. Nasopharyngoscopy showed lodgment of the toothbrush piece in the upper oropharynx, pulsating in synchrony with heartbeats. Computed tomography showed the toothbrush head near the carotid artery. The foreign body was surgically removed without any intraoperative or postoperative complications. The diagnosis and management of oropharyngeal injuries by stick-like foreign bodies, such as a toothbrush or chopsticks, are discussed.

Carotid Arteries↗

PubMed2005

Interfield differences in intensity and frequency representation of evoked potentials in rat auditory cortex.

Existing studies have demonstrated interfield differences in functional organizations and neuronal responsive properties at a single neuron level in the auditory cortex, suggesting complicated encoding of sound frequency and intensity. The objective of present work is, by characterizing cortical auditory evoked potentials (AEPs), to bridge neural characteristics between a single neuron and field levels and to identify the interfield differences in the auditory cortex specifically in terms of spatial representation, which will be useful in guiding future unit studies. The AEP mapping found that each of auditory fields, which could be identified by a different tonotopic representation, showed interfield differences in an intensity-dependent spatial change, amplitude, latency, and amplitude-SPL (sound pressure level) function. These results also showed that many aspects of cortical representation were based on the cochlear properties, yet some were inconsistent. The intensity-dependent shift of activation in AI paralleled the tonotopic axis, which was similar to the place code in cochlea, while the shift in AAF and VAF did not parallel. Nevertheless, the amplitude-SPL function suggested that an underlying mechanism of all these shifts can be a compressive nonlinearity to CF tone, which is possibly formed in the cochlea and still preserved in the cortex. These results suggest that each field modifies the representation to handle a different aspect of sound information, which can be better analyzed than the cochlear representation.

Acoustic Stimulation↗

PubMed2005

Auditory imagery mismatch negativity elicited in musicians.

A mismatch between auditory sensation and expectant imagery of syllables elicited a possible equivalent of mismatch negativity in a previous study. The purpose of this study was to verify whether auditory imagery from musical notation could also mediate such imagery-based mismatch negativity. Neuromagnetic recording was obtained from eight musicians, who were instructed to identify unpredictably occurring pitch mismatches between a random tone sequence and a visually presented musical score. The difference between incongruent and congruent responses showed a magnetic distribution consistent with two frontal-negative current dipoles bilaterally located in the vicinity of Heschl's gyrus, peaking at approximately 150 ms in latency. This imagery-based mismatch negativity may represent an early neural process of deviance detection between the sensory input and expectant imagery.

Acoustic Stimulation↗

PubMed2005

Sound lateralization test in adolescent blind individuals.

Blind individuals require to compensate for the lack of visual information by other sensory inputs. In particular, auditory inputs are crucial to such individuals. To investigate whether blind individuals localize sound in space better than sighted individuals, we tested the auditory ability of adolescent blind individuals using a sound lateralization method. The interaural time difference discrimination thresholds of blind individuals were statistically significantly shorter than those of blind individuals with residual vision and controls. These findings suggest that blind individuals have better auditory spatial ability than individuals with visual cues; therefore, some perceptual compensation occurred in the former.

Acoustic Stimulation↗