Publications (27)41.96 Total impact
-
Article: Extended screening for major mitochondrial DNA point mutations in patients with hereditary hearing loss.
[show abstract] [hide abstract]
ABSTRACT: Hearing loss (HL) is the most common sensory disorder in humans. Many patients with mitochondrial diseases have sensorineural HL (SNHL). The HL of these patients manifests as a consequence of either syndromic or nonsyndromic mitochondrial diseases. Furthermore, the phenotypes vary among patients even if they are carrying the same mutation. Therefore, these features make it necessary to analyze every presumed mutation in patients with hereditary HL, but the extensive analysis of various mutations is laborious. We analyzed 373 patients with suspected hereditary HL by using an extended suspension-array screening system for major mitochondrial DNA (mtDNA) mutations, which can detect 32 other mtDNA mutations in addition to the previously analyzed 29 mutations. In the present study, we detected 2 different mtDNA mutations among these 373 patients; m.7444G>A in the MT-CO1 gene and m.7472insC in the MT-TS1 gene in 1 patient (0.3%) for each. As these two patients had no clinical features other than HL, they had not been suspected of having mtDNA mutations. This extended screening system together with the previous one is useful for the genetic diagnosis and epidemiological study of both syndromic and nonsyndromic HL.Journal of Human Genetics advance online publication, 13 September 2012; doi:10.1038/jhg.2012.109.Journal of Human Genetics 09/2012; · 2.57 Impact Factor -
Article: Mitochondrial DNA haplogroup associated with hereditary hearing loss in a Japanese population.
[show abstract] [hide abstract]
ABSTRACT: Abstract Conclusion: Haplogroup D4b, especially subhaplogroup D4b2, may be one of the modifiers associated with the phenotypic expression of hereditary hearing loss (HL). Objectives: The present study investigated the association between suspected hereditary HL and 12 major mtDNA haplogroups in a Japanese population. Besides the mutations of mitochondrial DNA, many modifiers including environmental factors and genetic polymorphisms are involved in HL. Methods: The subjects comprised 373 unrelated Japanese patients with suspected hereditary HL and 480 controls. Twenty of the 373 patients were excluded from the study because the m.1555A>G or the m.3243A>G mutation had been detected in them. The mitochondrial haplotypes were classified into 12 major Japanese haplogroups (i.e. F, B, A, N9a, N9b, M7a, M7b, G1, G2, D4a, D4b, and D5). The frequency of each haplogroup in patients with HL was compared with that of the controls using the chi-squared test. Results: The frequency of the HL patients carrying the mitochondrial haplogroup D4b was significantly higher than that of the controls (37/353 [10.5%] vs 31/480 [6.5%]; OR 1.70 [95% CI 1.03-2.79, p = 0.036]) and evidence for enhancement was found in subhaplogroup D4b2 (32/353 [9.1%] vs 24/480 [5%], OR 1.89 [95% CI 1.09-3.28, p = 0.021]).Acta oto-laryngologica 07/2012; 132(11):1178-82. · 0.98 Impact Factor -
Article: [Intralabyrinthine schwannoma extending into the round window niche and internal auditory canal].
[show abstract] [hide abstract]
ABSTRACT: Intralabyrinthine schwannomas (ILSs) are rare benign neoplasms arising from distal branches of the cochlear, superior vestibular, or inferior vestibular nerves. We report on a case of ILS with extensions to the round window niche and internal auditory canal (IAC) in a 47-year-old male. The patient noticed sudden hearing loss and tinnitus in his left ear at the age of 36, received steroid therapies, but was left with complete deafness. He had suffered from repetitive vertigo attacks for 6 months at 41. At 46 when he presented with deterioration of his left tinnitus, he was finally diagnosed as having ILS on enhanced MRI and constructive interference in steady-state analysis. The tumor was located in all turns of cochlea, vestibule, and the fundus of the IAC. Because follow-up MRI suggested growth of the IAC tumor, we performed total removal of the tumor via the translabyrinthine and transcanal approaches. The tumor had invaded only the cochlear nerve in the IAC and appeared in the round window niche in the middle ear. Pathological examination showed an Antoni A type schwannoma with fibrous changes of the semicircular canals. We should remember this innerNippon Jibiinkoka Gakkai Kaiho 07/2012; 115(7):687-92. -
Article: [Audiological analysis and peri-and postoperative complications in bone-anchored hearing aid surgery].
[show abstract] [hide abstract]
ABSTRACT: The bone-anchored hearing aid (BAHA) has advantages over conventional hearing aids in sound quality and speech reception in silence, but requires surgery and may have peri-and postoperative complications. We evaluated audiological findings and complications in 12 subjects (13 ears)-8 men and 4 women aged 20-71--undergoing BAHA surgery from September 2001 to October 2005. Surgery was for single-sided deafness in one subject. Mean warble tone thresholds with BAHA were 29.9dB and 65.2dB without. Functional gains ranged from 16 to 52dB (mean: 35.3dB). Dural exposure or venous hemorrhage was seen in 4 ears, and mastoid cells opened and a skin flap was damaged in 1 ear each. No severe complications occurred perioperatively. Skin reactions categorized into grade 1 or more were recognized in nearly 70% of ears during the first postoperative year but most were a grade 1 reaction and skin reactions decreased with time. Skin overgrowth occurred in 1 ear immediately after an abutment separated accidentally from the fixture. All complications were treated in outpatient clinics. No fixture extrusion occurred. The decision to proceed with BAHA surgery thus required fully informed consent based on knowledge of peri-and postoperative complications.Nippon Jibiinkoka Gakkai Kaiho 07/2011; 114(7):607-14. -
Article: Audiovestibular findings in a branchio-oto syndrome patient with a SIX1 mutation.
[show abstract] [hide abstract]
ABSTRACT: A reported mutation in SIX1 was identified in a patient with familial hearing loss (HL), a left preauricular pit, and bilateral enlarged vestibular aqueducts (EVA). Although the characteristic symptoms of EVA including fluctuating HL and repetitive vertigo were not seen in the patient, further studies are needed to clarify the association between EVA and such symptoms. To study the audiovestibular functions, and to identify the causative gene in a patient with branchio-oto syndrome. We enrolled a 30-year-old female in whom HL was pointed out at the age of 6 years. She visited our department at the age of 21 years, and had not experienced any progression of her HL, tinnitus, or vertigo. Pure-tone audiograms showed bilateral moderate mixed HL with no apparent progression during a 9-year follow-up period. Audiovestibular examinations included distortion product otoacoustic emissions (DPOAEs), electrocochleography (ECochG), and electronystagmography (ENG). Direct sequencing was utilized to screen for SIX1, EYA1, SLC26A4, GJB2, and mitochondrial DNA MTRNR1 including 1555 position. The findings of DPOAEs, ECochG, and ENG indicated cochlear HL with no vestibular dysfunction. A previously reported mutation of a heterozygous c.386A > G (p.Y129C) in SIX1 was detected. No mutation was identified in EYA1, SLC26A4, GJB2, or MTRNR1.Acta oto-laryngologica 01/2011; 131(4):413-8. · 0.98 Impact Factor -
Article: Secondary hyperbaric oxygen therapy for idiopathic sudden sensorineural hearing loss in the subacute and chronic phases.
[show abstract] [hide abstract]
ABSTRACT: This study investigated the efficacy of hyperbaric oxygen therapy (HBOT) as a secondary treatment for patients with idiopathic sudden sensorineural hearing loss (ISSNHL) in the subacute and chronic phases. Forty-eight ISSNHL patients (HBOT group) who had received primary conventional treatment within 4 weeks after onset and underwent HBOT between 4 and 20 weeks post-onset were retrospectively compared with 44 ISSNHL patients (control group) with primary conventional treatment alone. Mean hearing gain was slight, with gains of 5.2 +/- 8.9 dB in the HBOT group and 2.0 +/- 7.6 dB in the control group. However, no significant difference was recognized between the two groups. In the HBOT group, no significant difference was observed in hearing gain among patients with HBOT initial time at 4-7, 8-11, 12-15 or 16-20 weeks after onset. Meanwhile, hearing gain was significantly higher in patients with profound hearing loss than in the other patients. We conclude that the effectiveness of secondary HBOT for ISSNHL patients in either subacute or chronic phase remains unproven, and thus, the decision administer HBOT should be made with caution.Journal of medical and dental sciences 06/2010; 57(2):127-32. -
Article: Hereditary hearing loss and deafness genes in Japan.
[show abstract] [hide abstract]
ABSTRACT: Hearing loss (HL) is the most common sensory impairment occurring at birth in developed countries. Epidemiological data show that more than one child in 1000 is born with HL, while more than 50% of prelingual HL cases are found to be hereditary. Approximately 70% of hereditary HL is nonsyndromic and subdivided to autosomal dominant (20%), autosomal recessive (75%), X-linked HL (1%), and maternally-inherited HL associated with the mitochondrial DNA mutation. More than 10 deafness genes have been reported to be responsible for nonsyndromic hereditary HL in Japan. Among them, the most prevalent causative genes, GJB2 and the mitochondrial DNA 12SrRNA are introduced. In addition, this study also refers to the specific genes responsible for the unique audiogram, mainly WFS1. Finally, the genes related to the enlargement of vestibular aqueduct of inner ear abnormality, SLC26A4, EYA1 and SIX1 are discussed. The clinical and genetic findings associated with these disorders including the results of a recent study are reviewed.Journal of medical and dental sciences 03/2010; 57(1):1-10. -
Article: Extensive and rapid screening for major mitochondrial DNA point mutations in patients with hereditary hearing loss.
[show abstract] [hide abstract]
ABSTRACT: Sensorineural hearing loss (HL) is one of the most frequent clinical features in patients with mitochondrial diseases caused by mitochondrial DNA (mtDNA) mutations, and hearing is impaired in over half of all cases with mitochondrial disorders. This study analyzed 373 patients with suspected hereditary HL using an extensive and rapid suspension-array screening system for 29 major mtDNA mutations, including the m.1555A>G homoplasmic mutation in the MT-RNR1 gene, which causes non-syndromic sensorineural HL and aminoglycoside-induced HL, and the m.3243A>G heteroplasmic mutation in the MT-TL1 gene. This method is rapid and suitable for large-scale screening because universal 96-well plates are available for use, and because an analysis of each plate can be completed within 1 h. This system detected five different mtDNA mutations in 24 of the 373 (6.4%) patients. The m.1555A>G and m.3243A>G mutations were detected in 11 (2.9%) and 9 (2.7%) patients, respectively. In addition, three mutations, that is, m.8348A>G in the MT-TK gene, m.11778G>A in the MT-ND4 gene and 15498G>A in the MT-CYB gene were detected in one patient for each. This screening system is useful for the genetic diagnosis and epidemiological study of both syndromic and non-syndromic HL.Journal of Human Genetics 03/2010; 55(3):147-54. · 2.57 Impact Factor -
Article: Novel ATP6V1B1 mutations in distal renal tubular acidosis and hearing loss.
[show abstract] [hide abstract]
ABSTRACT: Novel ATP6V1B1 mutations were found in a patient with distal renal tubular acidosis (dRTA), hearing loss (HL), and enlargement of the vestibular aqueduct (EVA). The deterioration of HL and vertiginous attacks may be associated with the disruption of the endolymph pH homeostasis. To study the audiovestibular functions and to identify the causative gene. This study enrolled a Japanese family, where the proband showed type 1 dRTA, early onset HL, and bilateral EVA. A deterioration of HL occurred several times in both ears. Vertiginous attacks were always associated with a deterioration of HL. Audiovestibular examinations included distortion product otoacoustic emissions (DPOAEs), auditory brainstem responses (ABRs), caloric testing, and vestibular evoked myogenic potentials (VEMPs). Direct sequencing was utilized to screen for ATP6V1B1, SLC26A4, and GJB2 mutations. The findings of DPOAEs and ABRs indicated cochlear HL. The vestibular function was thought to be mildly impaired according to the caloric responses and VEMP findings. Two novel ATP6V1B1 mutations of a heterozygous 15 base-pair deletion (c.756_770del) in exon 7 and a heterozygous 1 base-pair insertion (c.1242_1243insC) in exon 12 were detected in a compound heterozygous state. No mutation was identified in either SLC26A4 or GJB2.Acta oto-laryngologica 03/2010; 130(9):1002-8. · 0.98 Impact Factor -
Article: What do patients with hereditary deafness think of genetic studies?
[show abstract] [hide abstract]
ABSTRACT: We conducted an attitude survey for patients with hearing loss (HL). The aim of this study was to investigate the opinions of patients or parents of deaf children regarding the deafness gene, genetic testing and a gene related HL. A questionnaire was sent to 201 individuals who visited the Department of Otolaryngology, Tokyo Medical and Dental University and who received genetic testing for HL from September 2000 to January 2006. There were 14 questions in the questionnaire that were classified into four topics related to a deafness gene and hereditary HL, genetic testing, outpatient department of medical genetics/genetic counseling, and the results of genetic testing. The study consisted of 140 respondents (70%) of 201 administered surveys. Before visiting our department, only 36% of the respondents were aware that a genetic factor was a cause of HL. Despite our explanation of a deafness gene and hereditary HL, 23% of 134 respondents answered that they had not received any such explanation. Furthermore, 14% of the 103 respondents who had answered that they receive the explanation, however, they did not fully understand it. Thirty-nine percent of the respondents made their own decision regarding the genetic testing, whereas 53.5% received the tests upon the advice of a physician or family member. In contrast, 91% of the respondents had a positive attitude towards other future genetic tests. The existence of the genetic outpatient department or genetic counseling has been seldom acknowledged, but upon learning of its availability, nearly one third of the respondents indicated that they would like to receive genetic counseling. Although no respondent had social and/or family problems after being informed that they had a deafness gene mutation, some respondents worried about the result. The results of the survey suggested that the vast majority of the respondents were satisfied with genetic testing for HL and that the barriers to take the genetic test were less than expected. However, some respondents have a negative attitude towards genetic testing and counseling. Furthermore, the issue of disclosure may be burdensome to patients.Auris, nasus, larynx 02/2010; 37(4):422-6. · 0.58 Impact Factor -
Article: Additional heterozygous 2507A>C mutation of WFS1 in progressive hearing loss at lower frequencies.
[show abstract] [hide abstract]
ABSTRACT: To describe the audiological profiles in a Japanese family with autosomal dominant hereditary sensorineural hearing loss (SNHL) and to identify the causative gene. A family study at an academic tertiary referral center. A family with autosomal dominant hereditary SNHL was enrolled. Hearing loss (HL) of affected members showed mid-frequency SNHL in childhood and progressed at lower frequencies with age, resulting in low-frequency SNHL. To understand the pathology of HL of this family, we performed a genetic analysis of WFS1, TECTA, and GJB2 by direct sequencing, and further audiovestibular examinations, including speech audiometry, distortion product otoacoustic emissions, electrocochleography, auditory brainstem responses, and electronystagmography for some affected members. A heterozygous A-to-C nucleotide transversion (c.2507A>C), resulting in a lysine-to-threonine substitution at codon 836 (K836T) was identified in exon 8 of WFS1. K836T was segregated with HL in the 15 participants in the genetic study but was not detected in the 212 normal chromosomes. Only polymorphic changes were detected in TECTA and GJB2. Audiovestibular examinations indicated purely cochlear HL and normal vestibular function. The summating potential/action potential ratios in electrocochleography increased in the bilateral ears of the proband. The family described with autosomal dominant inheritance of K836T of the WFS1 gene demonstrates a progressive hearing loss in the lower frequencies.The Laryngoscope 10/2009; 120(1):166-71. · 1.75 Impact Factor -
Article: Vestibular evoked myogenic potentials in patients with the mitochondrial A1555G mutation.
[show abstract] [hide abstract]
ABSTRACT: To evaluate the vestibular function in patients with the mitochondrial DNA A1555G mutation. Data from patients with the mutation at an academic tertiary referral center were prospectively recorded. The histories of five unrelated patients with bilateral moderate to profound sensorineural hearing loss (SNHL) carrying the A1555G (A to G substitution at 1555 nucleotide) mutation were recorded, especially their history of vestibular symptoms. Thereafter, vestibular examinations, including positional, positioning and spontaneous nystagmus testing; caloric response testing; and vestibular evoked myogenic potential (VEMP) testing were performed. In the cases where the VEMP activity presented, the amplitudes of the first positive-negative peak (p13-n23) of the mutation group were compared to a healthy volunteer group and to a sudden SNHL group. Four of the five patients suffered from repetitive vestibular symptoms. Positioning, positional, and spontaneous nystagmus were not observed except in one patient. Three of the five patients had normal caloric responses, but all the patients had abnormal VEMPs. The interpeak amplitudes in the mutation group were significantly lower at the intensities of 95 and 105 dB normal hearing level (nHL) in comparison to the healthy volunteer group. In addition, the amplitudes in the mutation group were significantly lower at the intensity of 95 dB nHL in comparison to the sudden SNHL groups. These results indicated that the A1555G mutation can cause vestibular dysfunction, especially saccular dysfunction and cochlear dysfunction. Further studies are necessary to elucidate the pathophysiological nature of the inner ear dysfunction in patients with the A1555G mutation.The Laryngoscope 07/2009; 119(9):1874-9. · 1.75 Impact Factor -
Article: Deficiency of Vlgr1 resulted in deafness and susceptibility to audiogenic seizures while the degree of hearing impairment was not correlated with seizure severity in C57BL/6- and 129-backcrossed lines of Vlgr1 knockout mice.
[show abstract] [hide abstract]
ABSTRACT: Vlgr1 (very large G-protein coupled receptor 1) knockout mice against hybrid backgrounds of the 129/Ola and C57BL/6 mouse strains show hearing deficit and high susceptibility to audiogenic seizures. The present study examined how hearing impairment and susceptibility to audiogenic seizures in Vlgr1-deficient mice change according to the genetic background of 129 and C57BL/6 mouse strains, which are popular strains for genetic studies. C57BL/6 mice have normal hearing ability during adolescence and are resistant to audiogenic seizures, and the 129S1/SvImJ substrain does not have a severe hearing deficit or convulsions as a result of audiogenic seizures; therefore, these strains were chosen for the present backcross study. C57BL/6-backcrossed Vlgr1 knockout mice and 129 (129S1/SvImJ)-backcrossed Vlgr1 knockout mice were established and their phenotypes investigated. Vlgr1 knockout mice showed hearing loss and high susceptibility to audiogenic seizures regardless of their genetic backgrounds. 129-backcrossed Vlgr1 knockout mice exhibited 10-20dB more severe hearing loss than C57BL/6-backcrossed Vlgr1 knockout mice. In general, 129-backcrossed Vlgr1 knockout mice showed a higher incidence of wild running than C57BL/6-backcrossed Vlgr1 knockout mice, and this incidence became smaller as they matured. However, C57BL/6-backcrossed Vlgr1 knockout mice showed a significantly higher mortality rate as a result of auditory stimulation 3 weeks postnatally than 129-backcrossed mice.Neuroscience Letters 07/2009; 461(2):190-5. · 2.11 Impact Factor -
Article: A familial case of mitochondrial disease resembling Alport syndrome.
[show abstract] [hide abstract]
ABSTRACT: A 38-year-old man with mild sensorineural hearing loss, diabetes mellitus, proteinuria, and slight renal dysfunction was admitted to our hospital for a renal biopsy to determine the cause of kidney disease. His elder sister and mother also had sensorineural hearing loss and renal failure, suggesting the existence of a common genetic disease in this family. Although the clinical features of the patient were similar to features of Alport syndrome, renal biopsy revealed no sign of Alport syndrome. We next considered a possibility of a mitochondrial kidney disease described by Jansen in 1997. Indeed, genetic analysis of mitochondrial DNA clarified the existence of A3243G mutation in the patient and his sister. This syndrome should be recognized by nephrologists as a differential diagnosis of Alport syndrome, diabetic nephropathy, and primary glomerular diseases.Clinical and Experimental Nephrology 05/2008; 12(2):159-63. · 1.37 Impact Factor -
Article: Quantitative analysis of mRNA in human temporal bones.
[show abstract] [hide abstract]
ABSTRACT: Well-preserved mRNA could be extracted from frozen human inner ears. Therefore, this study demonstrates that analysis of mRNA could be performed to study the molecular mechanisms of inner ear disorders using human specimens. Analysis of RNA as well DNA is requisite to study the molecular mechanisms of inner ear disorders. Methods of isolating RNA from experimental animals have been established, while isolation of RNA from human inner ears is much more challenging. In the present study, we demonstrate a method by which messenger RNA (mRNA) was extracted from human inner ears and quantitatively analyzed. COCH mRNA as well as GAPDH mRNA was extracted from membranous labyrinths dissected from three formalin-fixed and three frozen human temporal bones, removed at autopsy. The length of COCH mRNA and quantity of GAPDH mRNA was compared between the two groups by quantitative RT-PCR. COCH mRNA could be amplified as much as 976 bp in all three frozen specimens. By contrast, it was amplified to 249 bp in two of the three formalin-fixed specimens, with no amplification observed in the remaining. The quantity of amplifiable GAPDH mRNA in the formalin specimens was only 1% of that of the frozen specimens.Acta Oto-Laryngologica 11/2007; 127(10):1024-30. · 1.08 Impact Factor -
Article: Multiple quantitative trait loci modify cochlear hair cell degeneration in the Beethoven (Tmc1Bth) mouse model of progressive hearing loss DFNA36.
[show abstract] [hide abstract]
ABSTRACT: Dominant mutations of transmembrane channel-like gene 1 (TMC1) cause progressive sensorineural hearing loss in humans and Beethoven (Tmc1Bth/+) mice. Here we show that Tmc1Bth/+ mice on a C3HeB/FeJ strain background have selective degeneration of inner hair cells while outer hair cells remain structurally and functionally intact. Inner hair cells primarily function as afferent sensory cells, whereas outer hair cells are electromotile amplifiers of auditory stimuli that can be functionally assessed by distortion product otoacoustic emission (DPOAE) analysis. When C3H-Tmc1Bth/Bth is crossed with either C57BL/6J or DBA/2J wild-type mice, F1 hybrid Tmc1Bth/+ progeny have increased hearing loss associated with increased degeneration of outer hair cells and diminution of DPOAE amplitudes but no difference in degeneration of inner hair cells. We mapped at least one quantitative trait locus (QTL), Tmc1m1, for DPOAE amplitude on chromosome 2 in [(C/B)F1xC]N2-Tmc1Bth/+ backcross progeny, and three other QTL on chromosomes 11 (Tmc1m2), 12 (Tmc1m3), and 5 (Tmc1m4) in [(C/D)F1xC]N2-Tmc1Bth/+ progeny. The polygenic basis of outer hair cell degeneration in Beethoven mice provides a model system for the dissection of common, complex hearing loss phenotypes, such as presbycusis, that involve outer hair cell degeneration in humans.Genetics 09/2006; 173(4):2111-9. · 4.01 Impact Factor -
Article: SIX1 mutation associated with enlargement of the vestibular aqueduct in a patient with branchio-oto syndrome.
[show abstract] [hide abstract]
ABSTRACT: : The objectives of this study were to identify SIX1 gene mutations in a patient with branchio-oto syndrome (BO) and to clarify the relationship between SIX1 mutation and enlargement of the vestibular aqueduct (EVA). : A genetic study and retrospective chart review for a patient in whom EYA1 mutation had already been excluded was conducted. We studied a Japanese patient who had autosomal-dominant mixed hearing loss, a unilateral ear pit and unilateral EVA, and who was previously diagnosed as having BO. We searched for SIX1 and SLC26A4 mutations using polymerase chain reaction and direct gene sequencing. : The patient carried a heterozygous A-->G mutation at nucleotide 386 within exon 1 of SIX1 that resulted in substitution of a cysteine for a tyrosine at codon 129 (Y129C) of the gene product. Y129C is a previously identified SIX1 mutation and was not detected in any of our 164 control chromosomes. No SLC26A4 mutations were identified. : Y129C mutation in SIX1 may cause EVA as well as BO.The Laryngoscope 06/2006; 116(5):796-9. · 1.75 Impact Factor -
Article: A mutation in Wolfram syndrome type 1 gene in a Japanese family with autosomal dominant low-frequency sensorineural hearing loss.
[show abstract] [hide abstract]
ABSTRACT: Our findings suggest that Wolfram syndrome type 1 gene (WFS1) mutation is an important cause of autosomal dominant low-frequency sensorineural hearing loss (LFSNHL) in Japan. DFNA6/14 is caused by a heterozygous mutation of WFS1 and is a common cause of autosomal dominant LFSNHL among populations in both Europe and the US. The purpose of this study was to investigate WFS1 mutations among Japanese patients whose phenotypes were consistent with those of DFNA6/14. Using audiometry and genetic analysis, we searched for WFS1 mutations in three unrelated Japanese patients with LFSNHL and a familial history of autosomal dominant hearing loss. One patient carried a heterozygous G2700A mutation at codon 844 in exon 8, resulting in substitution of a threonine for an alanine (A844T). Genetic analysis of the available members of the patient's family showed that the A844T mutation segregated with LFSNHL, but was not detected in any of 140 control chromosomes. It thus appears likely that the A844T mutation is causative for hearing loss in this group. Speech audiometry, self-recording audiometry and auditory brainstem responses showed the patient to have cochlear deafness without retrocochlear dysfunction. No mutation was found in the other two patients.Acta Oto-Laryngologica 12/2005; 125(11):1189-94. · 1.08 Impact Factor -
Article: An autosomal dominant cerebellar ataxia linked to chromosome 16q22.1 is associated with a single-nucleotide substitution in the 5' untranslated region of the gene encoding a protein with spectrin repeat and Rho guanine-nucleotide exchange-factor domains.
[show abstract] [hide abstract]
ABSTRACT: Autosomal dominant cerebellar ataxia (ADCA) is a group of heterogeneous neurodegenerative disorders. By positional cloning, we have identified the gene strongly associated with a form of degenerative ataxia (chromosome 16q22.1-linked ADCA) that clinically shows progressive pure cerebellar ataxia. Detailed examination by use of audiogram suggested that sensorineural hearing impairment may be associated with ataxia in our families. After restricting the candidate region in chromosome 16q22.1 by haplotype analysis, we found that all patients from 52 unrelated Japanese families harbor a heterozygous C-->T single-nucleotide substitution, 16 nt upstream of the putative translation initiation site of the gene for a hypothetical protein DKFZP434I216, which we have called "puratrophin-1" (Purkinje cell atrophy associated protein-1). The full-length puratrophin-1 mRNA had an open reading frame of 3,576 nt, predicted to contain important domains, including the spectrin repeat and the guanine-nucleotide exchange factor (GEF) for Rho GTPases, followed by the Dbl-homologous domain, which indicates the role of puratrophin-1 in intracellular signaling and actin dynamics at the Golgi apparatus. Puratrophin-1--normally expressed in a wide range of cells, including epithelial hair cells in the cochlea--was aggregated in Purkinje cells of the chromosome 16q22.1-linked ADCA brains. Consistent with the protein prediction data of puratrophin-1, the Golgi-apparatus membrane protein and spectrin also formed aggregates in Purkinje cells. The present study highlights the importance of the 5' untranslated region (UTR) in identification of genes of human disease, suggests that a single-nucleotide substitution in the 5' UTR could be associated with protein aggregation, and indicates that the GEF protein is associated with cerebellar degeneration in humans.The American Journal of Human Genetics 08/2005; 77(2):280-96. · 10.60 Impact Factor -
Article: Effect of beta-alanyl-L-histidinato zinc on the differentiation of C2C12 cells.
[show abstract] [hide abstract]
ABSTRACT: Although beta-alanyl-L-histidinato zinc (AHZ) can promote osteoblast differentiation, the molecular mechanism responsible is not fully understood. The purpose of this study was to determine the effect of AHZ on undifferentiating mesenchymal cells. C2C12, a typical pluripotential mesenchymal cell line, was used. The cells were cultured in 5% serum-containing medium to induce differentiation, either with or without the addition of AHZ. Cell lineage was determined by immunostaining of type II myosin heavy chains, alkaline phosphatase (ALPase) activity, mRNA expression of cellular phenotype-specific markers using semi-quantitative reverse transcriptase-polymerase chain reaction, and core binding factor alpha1/runt-related transcription factor-2 (Cbfa1/Runx2) protein synthesis using Western blot analysis. C2C12 cells cultured in the presence of AHZ were strongly inhibited from developing into myoblasts, and showed high ALPase activity that was approximately double that in the vehicle. The expression of mRNA for Cbfa1/Runx2, ALPase, Sox9 and type X collagen was increased markedly by the AHZ-stimulated medium, whereas that of desmin and MyoD mRNA was drastically decreased. AHZ increased Cbfa1/Runx2 protein expression substantially. These results provide clear evidence that AHZ converts the differentiation pathway of C2C12 cells to the osteoblast and/or chondroblast lineage.Life Sciences 01/2005; 76(5):509-20. · 2.53 Impact Factor
Top co-authors
Top Journals
Institutions
-
1997–2012
-
Tokyo Medical and Dental University
- • Department of Otolaryngology
- • Department of Otorhinolaryngology
Tokyo, Tokyo-to, Japan
-
-
2006
-
National Institutes of Health
- Division of Gene Structure and Function
Bethesda, MD, USA
-
