Search PubMed⌕ Search

Biomedical subjects

Ken Ito

Publications and source records attributed to Ken Ito.

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

Reversible impairment of auditory callosal pathway in 5-fluorouracil-induced leukoencephalopathy: parallel changes in function and imaging.

OBJECTIVE: To report the course of functional and imaging recovery of the auditory callosal pathway in a patient with 5-fluorouracil-induced leukoencephalopathy. DESIGN: Case study. SETTING: University hospital. PATIENT: A 58-year-old man with hypopharyngeal cancer who developed 5-fluorouracil-induced leukoencephalopathy. MAIN OUTCOME MEASURES: Imaging (magnetic resonance imaging) and functional (dichotic listening test) evaluation on the auditory callosal pathway. RESULTS: The patient underwent systemic chemotherapy with pirarubicin, cisplatin, and 5-fluorouracil. On the last day of the regimen, the patient suddenly became restless and convulsive. On diffusion-weighted magnetic resonance images, the signal intensity at the splenium of the corpus callosum was very high. Fluid-attenuated inversion recovery images showed no abnormal findings at this time. Intravenous methylprednisolone sodium succinate and glycerin 10% was started immediately. On the ninth day after onset, the patient was free of neurologic symptoms. Although pure-tone audiograms and speech discrimination scores were normal, dichotic listening tests revealed significant left ear suppression, indicating severe injury of the auditory callosal pathway. On fluid-attenuated inversion recovery images, the signal intensity at the splenium was high, whereas the posterior trunk was normal. At 6 weeks after onset, dichotic listening test results returned to normal and hyperintensity at the splenium was much less marked on fluid-attenuated inversion recovery images. CONCLUSION: By using both functional and imaging modalities, this case study demonstrated, for the first time in a reversible manner, that the auditory callosal pathway runs through the most posterior part of the corpus callosum including the splenium. Diffusion-weighted magnetic resonance imaging was considered useful for early diagnosis of 5-fluorouracil-induced leukoencephalopathy.

Antimetabolites, Antineoplastic↗
PubMed2006

Hypertrophic cranial pachymeningitis associated with middle ear inflammation.

OBJECTIVE: To describe a series of patients with hypertrophic cranial pachymeningitis (HCP) associated with chronic middle ear inflammation. STUDY DESIGN: Retrospective case review. SETTING: University Hospital. PATIENTS: Six consecutive patients between the years 2000 and 2004 who had both middle ear disease and HCP (three men and three women; age range, 36-72 yr, mean age, 58.2 yr). The diagnosis of HCP was made by the use of contrast-enhanced magnetic resonance imaging scans of the brain in all patients. INTERVENTIONS: Contrast-enhanced magnetic resonance imaging (MRI) of the brain, dural biopsy, and otomicroscopic examination. MAIN OUTCOME MEASURE: Thickening and abnormal enhancement of the dura mater on the MRI of the brain. RESULTS: All of the six patients had chronic inflammatory middle ear diseases. Three patients had otitis media with effusion, two had chronic otitis media, and one had postoperative otorrhea. The most common presentations of HCP were headache and cranial nerve palsies. Cranial Nerves V and VIII were the most frequently involved. On contrast-enhanced MRI examination of the brain, an enhancement of the dura mater was observed on the same side as the middle ear diseases in five of the six patients, whereas bilateral enhancement was observed in one patient. Corticosteroid therapy was effective for alleviating the symptoms in all six patients. CONCLUSION: Chronic middle ear inflammation might be involved in the pathogenesis of HCP, probably mediated by the venous return.

Adult↗
PubMed2006

Wilms' tumor gene WT1 17AA(-)/KTS(-) isoform induces morphological changes and promotes cell migration and invasion in vitro.

The wild-type Wilms' tumor gene WT1 is overexpressed in human primary leukemia and in a wide variety of solid cancers. All of the four WT1 isoforms are expressed in primary cancers and each is considered to have a different function. However, the functions of each of the WT1 isoforms in cancer cells remain unclear. The present study demonstrated that constitutive expression of the WT1 17AA(-)/KTS(-) isoform induces morphological changes characterized by a small-sized cell shape in TYK-nu.CP-r (TYK) ovarian cancer cells. In the WT1 17AA(-)/KTS(-) isoform-transduced TYK cells, cell-substratum adhesion was suppressed, and cell migration and in vitro invasion were enhanced compared to that in mock vector-transduced TYK cells. Constitutive expression of the WT1 17AA(-)/KTS(-) isoform also induced morphological changes in five (one gastric, one esophageal, two breast and one fibrosarcoma) of eight cancer cell lines examined. No WT1 isoforms other than the WT1 17AA(-)/KTS(-) isoform induced the phenotypic changes. A decrease in alpha-actinin 1 and cofilin expression and an increase in gelsolin expression were observed in WT1 17AA(-)/KTS(-) isoform-transduced TYK cells. In contrast, co-expression of alpha-actinin 1 and cofilin or knockdown of gelsolin expression by small interfering RNA restored WT1 17AA(-)/KTS(-) isoform-transduced TYK cells to a phenotype that was comparable to that of the parent TYK cells. These results indicated that the WT1 17AA(-)/KTS(-) isoform exerted its oncogenic functions through modulation of cytoskeletal dynamics. The present results may provide a novel insight into the signaling pathway of the WT1 gene for its oncogenic functions.

Actinin↗
PubMed2005

Alteration of frequency range for binaural beats in acute low-tone hearing loss.

The effect of acute low-tone sensorineural hearing loss (ALHL) on the interaural frequency difference (IFD) required for perception of binaural beats (BBs) was investigated in 12 patients with unilateral ALHL and 7 patients in whom ALHL had lessened. A continuous pure tone of 30 dB sensation level at 250 Hz was presented to the contralateral, normal-hearing ear. The presence of BBs was determined by a subjective yes-no procedure as the frequency of a loudness-balanced test tone was gradually adjusted around 250 Hz in the affected ear. The frequency range in which no BBs were perceived (FRNB) was significantly wider in the patients with ALHL than in the controls, and FRNBs became narrower in the recovered ALHL group. Specifically, detection of slow BBs with a small IFD was impaired in this limited (10 s) observation period. The significant correlation between the hearing level at 250 Hz and FRNBs suggests that FRNBs represent the degree of cochlear damage caused by ALHL.

Acute Disease↗
PubMed2005

Prolonged protective effect of short daily hemodialysis against dialysis-induced hypotension.

BACKGROUND/AIMS: Short daily hemodialysis (HD) has a protective effect against dialysis-induced hypotension (DIH). We examined whether this effect extends beyond the treatment period. METHODS: We analyzed clinical variables in 6 patients (5 with diabetes mellitus) who underwent conventional hemodialysis (CHD) for 4 h three times weekly for 12 weeks; then short daily HD for 2 h six times weekly for 12 weeks, and then 12 more weeks of CHD. All patients had been given vasopressors for severe DIH. RESULTS: The severe DIH disappeared during the short daily HD. There were significant decreases in body weight (BW), cardiothoracic ratio (CTR), blood pressure (BP), normal saline solution (NSS) amount (62.8 +/- 26.4 vs. 9.8 +/- 7.4 ml/session, p < 0.05), frequency (0.60 +/- 0.26 vs. 0.10 +/- 0.07 infusions/session, p < 0.05) and postdialysis atrial natriuretic peptide (ANP) (176.8 +/- 56.4 vs. 104.8 +/- 42.3 pg/ml, p < 0.05). Weekly ultrafiltration volume (6.3 +/- 0.9 vs. 7.9 +/- 0.7 l, p < 0.05) was significantly higher during the short daily HD period than during the first CHD period. The vasopressor treatment was therefore stopped or reduced in all patients during the short daily HD period. Because DIH recurred in the second CHD period despite a significant increase in BP, the vasopressor treatment was resumed in 5 patients. BW, CTR, NSS infusion amount and frequency, or postdialysis ANP did not differ significantly between the short daily HD and second CHD periods. CONCLUSIONS: The protective effect of short daily HD against DIH lasted more than 12 weeks after the treatment ended. We therefore conclude that temporary short daily HD is useful for preventing DIH.

Aged↗
PubMed2005

Extent of lesions in idiopathic sudden hearing loss with vertigo: study using click and galvanic vestibular evoked myogenic potentials.

OBJECTIVE: To clarify the extent of the vestibular lesions in idiopathic sudden hearing loss with vertigo using vestibular evoked myogenic potentials (VEMPs) in response to click (click-VEMP) and galvanic (galvanic-VEMP) stimulation, as well as caloric tests. DESIGN: Retrospective study. SETTING: University hospital. PATIENTS: We enrolled 22 patients with idiopathic sudden hearing loss with vertigo in this study. All patients underwent audiometry and click-VEMP and caloric tests. Eight patients underwent a galvanic-VEMP test. RESULTS: Among the 22 patients, 17 (77%) showed an absence of click-VEMPs on the affected side. In response to caloric testing, 10 patients (45%) showed a decreased response on the affected side. All 8 patients who underwent galvanic-VEMP testing showed normal responses. Most patients with decreased caloric responses (9 [90%] of 10 patients) showed an absence of click-VEMPs, whereas 9 (53%) of the 17 patients who showed abnormal click-VEMPs showed decreased caloric responses. Initial hearing level and hearing outcome significantly correlated with abnormalities on the vestibular test results. CONCLUSIONS: The lesion site of vestibular disorders in idiopathic sudden hearing loss with vertigo appeared to be within the labyrinth on the basis of galvanic-VEMP findings. Results of the click-VEMP and caloric tests suggested that the saccule could be involved more frequently than the semicircular canals. The combined use of click-VEMP and caloric tests is useful for evaluating vestibular functions in idiopathic sudden hearing loss with vertigo because the extent of vestibular abnormalities correlated well with hearing outcome.

Adult↗
PubMed2005

Correlation between microtia and temporal bone malformation evaluated using grading systems.

OBJECTIVE: To evaluate the relationships between temporal bone abnormalities and the severity of microtia in Japanese patients using objective grading systems. DESIGN: Retrospective case series study conducted between 1992 and 2003. SETTING: Academic, tertiary care, referral medical center. PATIENTS: One hundred forty-two ears of 109 Japanese patients (85 male and 24 female patients; mean age, 12.8 years [range, 2-36 years]) with microtia. MAIN OUTCOME MEASURES: The severity of microtia was classified according to Marx classification. Developmental abnormalities of the temporal bone were evaluated by a computed tomographic (CT) scoring system modified after the system used by Jahrsdoerfer and colleagues, using high-resolution CT scans of the temporal bone. Correlations between the scores obtained from these 2 grading systems were evaluated using a nonparametric statistical method. RESULTS: Male preponderance and incidence of bilateral cases of approximately 30% were observed in our Japanese patients with microtia. There was no significant difference in the severity of microtia between unilateral and bilateral cases. The mean +/- SEM total points in the CT scoring system (full marks, 10) was 7.9 +/- 0.4 for grade I microtia, 6.6 +/- 0.6 for grade II, and 6.4 +/- 0.3 for grade III; the total points correlated inversely with the microtia grade. Development of the auricle correlated significantly with aeration in the middle ear spaces but not with ossicular development or formation of the oval/round windows. Proportion of acceptable surgical candidates according to the CT scoring system (>5 points) was 79% for grade I microtia, 52% for grade II microtia, and 65% for grade III microtia. CONCLUSION: The principle "the better developed the auricle, the better developed middle ear" was confirmed in Japanese patients with microtia; however, even with grade II/III microtia, more than half of the patients were considered suitable for atresia surgery.

Abnormalities, Multiple↗
PubMed2005

Independent effects of simultaneous inputs from the saccule and lateral semicircular canal. Evaluation using VEMPs.

OBJECTIVE: To determine the effects of stimulation of bilateral lateral semicircular canals (LSCCs) by accelerated rotation and caloric stimulation of unilateral LSCC on vestibular evoked myogenic potentials (VEMPs) in healthy volunteers. METHODS: In experiment 1, VEMPs were recorded while subjects (n = 11) were seated in a rotational chair and angular acceleration around the earth-vertical axis was provided. Amplitudes of p13-n23 were corrected using background muscle activities. In experiment 2, subjects (n = 8) in the semilateral position kept the LSCC in the vertical position and activated the sternocleidomastoid muscle by twisting the neck. After irrigating the external auditory canal with ice water, VEMPs were recorded on the irrigated side. In experiment 3, the same setting as experiment 2 was applied (n = 6), and hot water of 44 degrees C was used for irrigation. RESULTS: There were no significant differences in latencies of p13 or n23, and in corrected amplitudes by either rotatory or caloric stimulation. CONCLUSIONS: Simultaneous stimulation of LSCCs has little effect on VEMPs. SIGNIFICANCE: No functional interaction between the saccule and LSCC was detected in VEMPs, although convergence of semicircular canal and otolith nerve inputs onto single vestibular nucleus neurons has been demonstrated electrophysiologically in animal experiments.

Adult↗
PubMed2005

Neuro-otologic findings in unilateral isolated narrow internal auditory meatus.

OBJECTIVE: To report neuro-otologic findings concerning the four nerves in the internal auditory meatus (IAM) in patients with isolated congenitally narrow IAM and explore the implications regarding ontogeny of the nerves in the IAM. DESIGN: Retrospective case series study. SETTING: University hospital. SUBJECTS: Five consecutive patients between 1997 and 2002 with unilateral isolated narrow IAM demonstrated by high-resolution computed tomography whose chief complaint was hearing loss (1 male and 4 females, 4 right sides and 1 left; age range 5-37 years, mean 20 years; IAM diameter at the porus: 26-33% of that on the normal side). MAIN OUTCOME MEASURES: Functional studies concerning the VIIth cranial nerve and the three branches of the VIIIth cranial nerve. RESULTS: In all ears, auditory brain stem responses were absent, the speech discrimination score was 0%, and otoacoustic emissions were absent or markedly reduced compared with those on the normal side. Caloric responses were absent in two ears, reduced in two ears, and normal in one ear. Galvanic body sway tests showed no responses in the two ears in which caloric responses were absent. Inferior vestibular nerve function was estimated as normal in all ears on the basis of vestibular evoked myogenic potential recordings. Facial nerve functions were normal in all patients. CONCLUSIONS: In isolated congenital stenosis of IAM, dysfunction of each nerve in the IAM can occur independently. In the ontogeny of the VIIIth cranial nerve, the cochlear and superior vestibular nerves tended to be involved together, whereas the cochlear and inferior vestibular nerves appeared independent of each other.

Adolescent↗
PubMed2005

Abnormal vestibular evoked myogenic potentials in the presence of normal caloric responses.

OBJECTIVE: Combined use of vestibular evoked myogenic potential (VEMP) and caloric response testing has enabled us to examine the function of the inferior and superior vestibular nerves separately. Although results of VEMP testing and caloric response testing have been reported for many diseases, a clinical entity showing abnormal VEMP responses but normal caloric test responses has rarely been reported. The aim of the study was to investigate clinical features of diseases showing abnormal VEMP responses with normal caloric test responses. STUDY DESIGN: Retrospective. SETTING: University hospital. PATIENTS: Eight hundred eleven patients with balance problems who had undergone both caloric response and VEMP testing were included in the study. MAIN OUTCOME MEASURES: The amplitudes and latencies of the first positive-negative peak of the VEMP (p13-n23) were measured. RESULTS: Forty of the 811 patients (5%) were found to have abnormal VEMP responses with normal caloric test responses. Clinical diagnoses of these patients were Ménière's disease (n = 12), acoustic neuroma (n = 8), sudden deafness with vertigo (n = 6), and other diseases (n = 6). Eight patients could not be diagnosed as having a disease already recognized. Clinical manifestations of these eight patients were rotatory vertigo in six patients and non-rotatory dizziness in two. None of these patients showed abnormalities other than VEMP responses on neurologic or neurotologic examinations. CONCLUSION: Apart from Ménière's disease, acoustic neuroma, and sudden deafness with vertigo, which are already known as diseases with abnormal VEMP responses but normal caloric test responses, some patients might be diagnosed as having a disease that involves only the inferior vestibular nerve region.

Adult↗
PubMed2005

Nonsyndromic isolated unilateral cochlear nerve aplasia without narrow internal auditorymeatus: a previously overlooked cause of unilateral profound deafness in childhood.

OBJECTIVES: Juvenile or adolescent unilateral profound sensorineural deafness (worldwide prevalence, 0.1% to 0.2%) has been attributed to postnatal viral infection, sudden deafness, prenatal and perinatal problems including maternal rubella and viral infections, congenital innerear anomalies, and other factors. Herein, 2 cases are reported and another potentially important cause of unilateral profound hearing loss is proposed. METHODS: Two nonsyndromic cases of a presently "very rare" cause of pediatric unilateral deafness are presented as a retrospective case study. RESULTS: The 2 patients showed isolated aplasia of the cochlear nerve; other branches of the eighth cranial nerve, the seventh nerve, and the inner ear were spared,and there was no anomaly of the internal auditory meatus. Both functional and imaging studies confirmed the isolated lesion (absence) of the cochlear nerve. CONCLUSIONS: Because of the absence of bony abnormalities, such cases may have been overlooked. The authors would like to advocate this isolated anomaly of thecochlear nerve as an important cause of juvenile or adolescent unilateral profound deafness.

Child↗
PubMed2004

Cortical activation shortly after cochlear implantation.

We evaluated the cortical activations in postlingually deaf cochlear implant (CI) users in the early period (0-2 months) of CI usage. The subjects were 8 early CI users and 8 normal subjects. With tone burst stimuli (1 kHz) delivered to the right side, strong and broad activation of the ipsilateral (right) primary auditory cortex with 2 peaks and weaker activation of the contralateral (left) temporal lobe were observed in early CI users, in a clear contrast with the normal subjects in whom activation was observed in a small area of the contralateral (left) primary cortex. With word stimuli, activation of the superior frontomedian cortex presumably including the supplementary motor area and the neighboring cingulate gyri was observed in early CI users, which was absent in normal subjects. The activation in the immediate association cortices near the primary area was lower in early CI users, while the periphery of the association cortex seemed to be more mobilized.

Acoustic Stimulation↗
PubMed2004

The role of the external auditory canal in the development of the malleal manubrium in humans.

OBJECTIVE: To determine if the external auditory canal (EAC) plays a role in the induction and proper positioning of the malleal manubrium in humans. STUDY DESIGN: Retrospective study between 1994 and 2002. SETTING: Academic, tertiary care referral medical center. Patients Fifty-five ears of 50 patients with congenital atresia (n = 47) or stenosis (n = 8) of the EAC, for which meatoplasty was performed at the University hospital between 1994 and 2002. MAIN OUTCOME MEASURES: The presence of the manubrium was examined during surgery, and the corre-lation between the presence of the manubrium and the grade of the microtia was evaluated. RESULTS: The manubrium was identified in all ears with EAC stenosis, whereas it was absent in all ears with EAC atresia. No correlation was observed between manubrium formation and auricular deformity. CONCLUSIONS: Our results demonstrated a close relationship between the formation of the EAC and that of the malleal manubrium in humans. This is consistent with the recent findings in knockout mice. This information is useful for surgical intervention in cases of congenital EAC anomalies.

Adolescent↗
PubMed2004

Prediction of canal paresis using head-shaking nystagmus test.

OBJECTIVE: To compare the incidence of head-shaking nystagmus (HSN) with the value of canal paresis (CP) obtained from a caloric test and to propose the optimal value of CP that can be predicted by the presence of HSN. MATERIAL AND METHODS: HSN and caloric tests, together with other vestibular tests, were performed in 132 dizzy patients. HSN was recorded using electronystagmography with Frenzel's glasses. RESULTS: HSN was observed in 61/132 patients (46%). The sensitivity and specificity of the HSN test regarding the prediction of CP>20% were 66% and 77%, respectively. CP values were significantly higher in patients with than without HSN. Both the sensitivity and specificity of HSN were reasonably high when the limiting value of CP was set between 20% and 30%. CONCLUSION: The limiting value of CP that discriminates the presence of HSN may be approximately 20%. At this CP value, HSN shows an appropriately high sensitivity and specificity. The HSN test is not very sensitive but is still acceptable as one of the screening tests for detecting asymmetrical vestibular dysfunction.

Ear Canal↗
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↗