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Shin-ichi Usami

Publications and source records attributed to Shin-ichi Usami.

10 recordsLinked to original sources
PubMed2003

GJB2 deafness gene shows a specific spectrum of mutations in Japan, including a frequent founder mutation.

Mutations in the GJB2 gene (connexin 26) are the major cause of autosomal recessive non-syndromic hearing impairment in many populations. In contrast to the volume of information regarding the involvement of GJB2 mutations in hearing impairment in populations of European ancestry, less is known regarding other ethnic groups. In this study, we analyzed the GJB2 gene for mutations in 1227 hearing-impaired Japanese individuals. This revealed a unique spectrum of GJB2 mutations, different from that found in the Caucasian population. The most frequent mutation in Japanese, 235delC, has never been reported in Caucasians. To investigate a possible founder effect for the 235delC mutation, we analyzed single nucleotide polymorphisms in the vicinity of the GJB2 gene. Results were consistent with inheritance of the 235delC mutation from a common ancestor. The results of this study have important implications for genetic diagnostic testing for deafness in the Japanese population.

Amino Acid Sequence↗
PubMed2003

Construction and characterization of a vestibular-specific cDNA library using T7-based RNA amplification.

Using a very small amount of inner-ear tissue, we constructed a human vestibular cDNA library by means of T7-based amplification of RNA. This library should allow us to identify genes likely to be involved in auditory and vestibular functions. Here we first report the characterization of the human vestibular cDNA library. Among 506 cDNA clones randomly selected from the vestibular cDNA library, DNA sequences of 301 cDNA clones were identical to those of genes of known function. Twenty-two cDNA clones were considered to be novel because they did not match any cDNA sequences in the public database. The information in our study will provide a valuable resource for identifying several novel genes underlying deafness disorders and vestibular dysfunction.

Bacteriophage T7↗
PubMed2003

Effect of single-drug treatment on idiopathic sudden sensorineural hearing loss.

OBJECTIVES: In order to evaluate the effect of a medical administration for the sudden deafness patients, single-drug treatment for idiopathic sudden sensorineural hearing loss (ISSHL) was assessed at multi-centers participating in the Acute Severe Hearing Loss Study Group sponsored by the Ministry of Health, Labor and Welfare of Japan. METHODS: The subjects consisted of ISSHL patients who were (1) 20 years of age or older, (2) diagnosed within 2 weeks after the onset of hearing loss, (3) showing a mean hearing level of 40-90 dB at five frequencies from 250 to 4000 Hz, (4) previously untreated, and (5) with normal for age in hearing of the opposite ear. The drugs used in this study were ATP, alprostadil, hydrocortisone and amidotrizoate, which were administered intravenously, and beraprost sodium and betamethasone, which were given orally. Two drugs were assigned to each center, one of which was selected according to the code hidden in envelopes and administered for 1 week. The treatment after the single-drug administration was conducted at the discretion of each center. The hearing gain and recovery rate at 1 week after the initiation of single-drug treatment and at 1 month or over when the hearing level was fixed, were evaluated based on the criteria for hearing recovery prepared by the Acute Severe Hearing Loss Study Group. RESULTS: There was no statistically significant difference in the recovery rate among drugs either at 1 week after the initiation of single-drug treatment or at the time of fixed hearing level. At the time when the hearing level was fixed, a statistically significant difference in the complete recovery rate was detected only between amidotrizoate and beraprost sodium. CONCLUSION: From these results, we could not find any specific drugs recommended for ISSNHL. In evaluating the effect of the drugs, however, several problems in the clinical trial for ISSHL should be considered.

Adenosine Triphosphate↗
PubMed2003

Malignant peripheral nerve sheath tumor of the parotid gland.

Malignant peripheral nerve sheath tumor (MPNST) has been defined as any malignant tumor arising from or differentiating toward cells of the peripheral nerve sheath. We treated a case of MPNST arising from the right parotid gland that showed a highly aggressive course. We reviewed the English-language literature published since 1990 and found 142 cases of head and neck MPNST reported within the past 13 years. The results of the review suggested that MPNSTs may arise from any organs of the head and neck. Immunohistochemical analysis of various neural markers plays a significant role in the evaluation of the histologic diagnosis. Curative treatment based on radical resection of MPNSTs of head and neck origin is more difficult than treatment of MPNSTs of other origins.

Humans↗
PubMed2002

Identification of CRYM as a candidate responsible for nonsyndromic deafness, through cDNA microarray analysis of human cochlear and vestibular tissues.

Through cDNA microarray analysis of gene expression in human cochlea and vestibule, we detected strong expression of mu-crystallin (CRYM; also known as "NADP-regulated thyroid hormone-binding protein") only in these inner-ear tissues. In a subsequent search for mutations of CRYM, among 192 patients with nonsyndromic deafness, we identified two mutations at the C-terminus; one was a de novo change (X315Y) in a patient with unaffected parents, and the other was a missense mutation (K314T) that segregated dominantly in the proband's family. When the mutated proteins were expressed in COS-7 cells, their subcellular localizations were different from that of the normal protein: the X315Y mutant showed vacuolated distribution in the cytoplasm, and the K314T mutant localized in perinuclear areas, whereas normal protein was distributed homogeneously in the cytoplasm. Aberrant intracellular localization of the mutated proteins might cause dysfunction of the CRYM product and result in hearing impairment. In situ hybridization analysis using mouse tissues indicated its expression in the lateral region of the spiral ligament and the fibrocytes of the spiral limbus, implying its possible involvement in the potassium-ion recycling system. Our results strongly implicate CRYM in normal auditory function and identify it as one of the genes that can be responsible for nonsyndromic deafness.

Amino Acid Sequence↗
PubMed2002

Role of visual input in nonlinear postural control system.

Stabilometry signals involve irregular and unpredictable components. The purpose of the present study was to investigate these signals with a nonlinear technique to examine how the complexity of the postural control system breaks down under altered visual conditions. We evaluated the dynamical similarities of the postural control system when the eyes were open or closed, or when there was optokinetic stimulation (OKS). A similarity index was calculated by the cross-correlation integral between the two dynamics: eyes open and eyes closed, or eyes open with OKS. Using this technique, dynamical changes were not observed between eyes-open and eyes-closed conditions. This result suggests that the nonvision condition does not produce any striking effect on the postural control system; instead, the eyes-open condition causes a decrease in the stochastic activity of the postural control system, which may originate mainly from the stiffness of the musculoskeletal systems. In contrast, the visual input of OKS affected the dynamics of the postural control system in nearly half of the subjects (group 2) despite showing no significant differences between the eyes-open condition and the other conditions for area as the conventional parameter. However, the other half of the subjects (group 1) did not experience any influence of OKS on their postural dynamics, despite showing significant differences between eyes-open and the other conditions for all traditional parameters. From the results for group 2, we hypothesize that OKS may induce the striking effect on dynamics properties of the multilink network system involving visual and vestibular cortex related to self-motion perception, which acts to decrease the stochastic activity in order to correct disturbed posture.

Adult↗
PubMed2002

Microtubule associated protein (MAP1A) mRNA was up-regulated by hypergravity in the rat inner ear.

Differential display analysis of differential mRNA expression in the rat inner ear under hypergravity identified two down- and four up-regulated genes. The up-regulation of microtubule associated protein 1A (MAP1A) in one of these was confirmed by real-time polymerase chain reaction. Since MAP1A is believed to work as a cell stabilizer connecting the actin with microtubule, this is possibly a response to strengthen this stabilizer under hypergravity. The MAP1A gene is the first found to be affected by gravity change in the inner ear.

Animals↗
PubMed2002

Identification of 605ins46, a novel GJB2 mutation in a Japanese family.

Connexin 26 gene (GJB2) mutations are known to be responsible for a significant portion (30-80%) of autosomal recessive congenital severe to profound deafness. More than 60 recessive mutations in GJB2 have been reported and most consist of point mutations of a nucleotide. We report here a novel insertional GJB2 mutation consisting of a long repetitive nucleotide sequence. As compound heterozygotes of this mutation with 235delC express sensorineural hearing loss of variable severity, further analysis of the phenotype-genotype relationship is required.

Child↗
PubMedDate not supplied

Molecular diagnosis of deafness: impact of gene identification.

Recent progress in identifying genes responsible for hearing loss enables the ENT clinician to apply molecular diagnosis by genetic testing. This article focuses on three genes, which are prevalent and therefore commonly encountered in the clinic. GJB2 (connexin 26) is currently recognized as the most prevalent gene responsible for congenital hearing loss in many countries. A series of reports revealed that different combinations of GJB2 mutations exist in different ethnic populations, indicating that ethnic background should be considered when performing genetic testing. GJB2 mutations will be of particular interest in combination with universal infant hearing screening programs, because it has been shown that early identification of hearing loss and early intervention are crucial for language development. Progress in genetic analysis has changed the concept of diseases. The present review introduces the example of two historically distinct categories of disease, Pendred syndrome and nonsyndromic hearing loss associated with enlarged vestibular aqueduct, which are currently considered to be a continuum of diseases caused by the same gene, PDS. This review also emphasizes that some hearing impairment can be prevented. The 1555A-->G mitochondrial mutation, the most prevalent mitochondrial mutation found in the hearing-impaired population, was found in approximately 3% of the outpatients. The 1555A-->G mutation is known to be associated with a susceptibility to aminoglycoside antibiotics. There may be a considerably large high-risk population and to avoid possible side effects in this group, a rapid mass screening system and careful counseling are recommended.

Carrier Proteins↗