Hitoshi Osaka
Jichi Medical University, Pediatrics, Faculty Member
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Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) at onset manifests an early seizure (ES) usually lasting more than 30min. Following ES, some patients exhibit almost clear consciousness with no neurological... more
Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) at onset manifests an early seizure (ES) usually lasting more than 30min. Following ES, some patients exhibit almost clear consciousness with no neurological symptoms, and no MRI abnormality for a few days, which may lead to an initial misdiagnosis of prolonged febrile seizures (PFS). To allow an early diagnosis of AESD, we retrospectively analyzed clinical manifestations, laboratory data, and radiologic and EEG findings in patients with AESD (n=62) having ES of over 30min, and ones with PFS (n=54), using logistic regression analyses. Multivariate logistic regression analysis revealed that an age below 1.5years and a Glasgow Coma Scale score of 14 or less than 14 (Japan Coma Scale score of 1 or higher) were high risk factors of developing AESD. We proposed an AESD prediction score system consisting of consciousness level, age, duration of convulsions, enforcement of mechanical intubation, and aspartate ami...
Research Interests: Electroencephalography, Humans, Female, Male, Glasgow Coma Scale, and 14 moreInfant, Differential Diagnosis, Risk factors, Clinical Sciences, Age Factors, Risk Factors, Seizures, Unconsciousness, Syndrome, Neurosciences, Severity of Illness Index, Acute Disease, Child preschool, and Diffusion magnetic resonance imaging
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Summary: Proton MR spectroscopic findings in two patients with genetically defined Pelizaeus-Merzbacher disease revealed ratios of N-acetylaspartate/creatine and choline-containing compounds/creatine that were not significantly different... more
Summary: Proton MR spectroscopic findings in two patients with genetically defined Pelizaeus-Merzbacher disease revealed ratios of N-acetylaspartate/creatine and choline-containing compounds/creatine that were not significantly different from those found in a population of healthy subjects. These findings suggest that proton MR spectroscopy can aid in the diagnosis of Pelizaeus-Merzbacher disease. Pelizaeus-Merzbacher disease (PMD) is a rare dysmyelinating disorder that affects the
Research Interests: Genetics, Creatine, Magnetic Resonance Spectroscopy, Adolescent, Energy Metabolism, and 15 moreHumans, Child, MR spectroscopy, Male, Magnetic Resonance, Central Nervous System, D-Aspartic Acid, Clinical Sciences, White matter, Sequential Analysis, Choline, Reference Values, Mr Imaging, Healthy Subjects, and Neurosciences
We report a third mutation of the proteolipid protein gene in male Japanese patients with X-linked spastic paraplegia. Although the proteolipid protein gene encodes two myelin proteins, proteolipid protein and DM 20, our W144X mutation... more
We report a third mutation of the proteolipid protein gene in male Japanese patients with X-linked spastic paraplegia. Although the proteolipid protein gene encodes two myelin proteins, proteolipid protein and DM 20, our W144X mutation resides in the latter part of exon 3 (exon 3B), which is spliced out in DM 20. This mutation may reserve the function of DM
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De novo GNAO1 variants have been found in four patients including three patients with Ohtahara syndrome and one patient with childhood epilepsy. In addition, two patients showed involuntary movements, suggesting that GNAO1 variants can... more
De novo GNAO1 variants have been found in four patients including three patients with Ohtahara syndrome and one patient with childhood epilepsy. In addition, two patients showed involuntary movements, suggesting that GNAO1 variants can cause various neurological phenotypes. Here we report an additional four patients with de novo missense GNAO1 variants, one of which was identical to that of the previously reported. All the three novel variants were predicted to impair Gαo function by structural evaluation. Two patients showed early-onset epileptic encephalopathy, presenting with migrating or multifocal partial seizures in their clinical course, but the remaining two patients showed no or a few seizures. All the four patients showed severe intellectual disability, motor developmental delay, and involuntary movements. Progressive cerebral atrophy and thin corpus callosum were common features in brain images. Our study demonstrated that GNAO1 variants can cause involuntary movements an...
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We report molecular analysis of thiamin-responsive pyruvate dehydrogenase complex (PDHC) deficiency in a patient with an X-linked form of Leigh syndrome. PDHC activity in cultured lymphoblastoid cells of this patient and his asymptomatic... more
We report molecular analysis of thiamin-responsive pyruvate dehydrogenase complex (PDHC) deficiency in a patient with an X-linked form of Leigh syndrome. PDHC activity in cultured lymphoblastoid cells of this patient and his asymptomatic mother were normal in the presence of a high thiamin pyrophosphate (TPP) concentration (0.4 mmol/L). However, in the presence of a low concentration (1 x 10(-4) mmol/L) of TPP, the activity was significantly decreased, indicating that PDHC deficiency in this patient was due to decreased affinity of PDHC for TPP. The patient's older brother also was diagnosed as PDHC deficiency with Leigh syndrome, suggesting that PDHC deficiency in these two brothers was not a de novo mutation. Sequencing of the X-linked PDHC E1 alpha subunit revealed a C-->G point mutation at nucleotide 787, resulting in a substitution of glycine for arginine 263. Restriction enzyme analysis of the E1 alpha gene revealed that the mother was a heterozygote, indicating that th...
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We performed whole-exome sequencing analysis of patients with genetically unsolved hypomyelinating leukoencephalopathies, identifying 8 patients with TUBB4A mutations and allowing the phenotypic spectrum of TUBB4A mutations to be... more
We performed whole-exome sequencing analysis of patients with genetically unsolved hypomyelinating leukoencephalopathies, identifying 8 patients with TUBB4A mutations and allowing the phenotypic spectrum of TUBB4A mutations to be investigated. Fourteen patients with hypomyelinating leukoencephalopathies, 7 clinically diagnosed with hypomyelination with atrophy of the basal ganglia and cerebellum (H-ABC), and 7 with unclassified hypomyelinating leukoencephalopathy, were analyzed by whole-exome sequencing. The effect of the mutations on microtubule assembly was examined by mapping altered amino acids onto 3-dimensional models of the αβ-tubulin heterodimer. Six heterozygous missense mutations in TUBB4A, 5 of which are novel, were identified in 8 patients (6/7 patients with H-ABC [the remaining patient is an atypical case] and 2/7 patients with unclassified hypomyelinating leukoencephalopathy). In 4 cases with parental samples available, the mutations occurred de novo. Analysis of 3-dim...
Research Interests: Cognitive Science, Neurology, Adolescent, Humans, Child, and 13 moreCerebellum, Mutation, Female, Male, Young Adult, Infant, Phenotype, Clinical Sciences, Adult, Basal ganglia, Tubulin, Neurosciences, and Exome
Aminoacylation is the process of attaching amino acids to their cognate tRNA, and thus is essential for the translation of mRNA into protein. This direct interaction of tRNA with amino acids is catalyzed by aminoacyl-tRNA synthetases.... more
Aminoacylation is the process of attaching amino acids to their cognate tRNA, and thus is essential for the translation of mRNA into protein. This direct interaction of tRNA with amino acids is catalyzed by aminoacyl-tRNA synthetases. Using whole-exome sequencing, we identified compound heterozygous mutations [c.169T>C (p.Tyr57His) and c.1485dup (p.Lys496*)] in QARS, which encodes glutaminyl-tRNA synthetase, in two siblings with early-onset epileptic encephalopathy (EOEE). Recessive mutations in QARS, including the loss-of-function missense mutation p.Tyr57His, have been reported to cause intractable seizures with progressive microcephaly. The p.Lys496* mutation is novel and causes truncation of the QARS protein, leading to a deletion of part of the catalytic domain and the entire anticodon-binding domain. Transient expression of the p.Lys496* mutant in neuroblastoma 2A cells revealed diminished and aberrantly aggregated expression, indicating the loss-of-function nature of this mutant. Together with the previous report, our data suggest that abnormal aminoacylation is one of the underlying pathologies of EOEE.
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We report on a 1-year-old boy with microcephaly with a simplified gyral pattern, early-onset seizures, congenital hearing loss and a severe developmental delay. Trio-based whole-exome sequencing identified candidate compound heterozygous... more
We report on a 1-year-old boy with microcephaly with a simplified gyral pattern, early-onset seizures, congenital hearing loss and a severe developmental delay. Trio-based whole-exome sequencing identified candidate compound heterozygous mutations in two genes: c.163G>T (p.Ala55Ser) and c.874G>A (p.Gly292Arg) in polynucleotide kinase 3'-phosphatase gene (PNKP), and c.195G>A (p.Met65Ile) and c.1210A>C (p.Ser404Arg) in PCDH15. PNKP and PCDH15 mutations have been reported in autosomal recessive microcephaly with early-onset seizures and developmental delay syndrome, and Usher syndrome type 1F, respectively. Our patient showed neurological features similar to reported cases of both syndromes that could be explained by the observed mutations in both PNKP and PCDH15, which therefore appear to be pathogenic in this case.
Research Interests: Genetics, Genetic Epidemiology, Human Genetics, Genomics, Population Genetics, and 15 moreMolecular Genetics, Epigenetics, Cytogenetics, Humans, Mutation, Microcephaly, Pharmacogenetics, Clinical Genetics, Male, Infant, Developmental disabilities, Hearing Loss, Clinical Sciences, Human Genome, and Seizures
Early‐onset epileptic encephalopathies (EOEE) are severe neurological disorders characterized by frequent seizures accompanied by developmental regression or retardation. Whole‐exome sequencing of 12 patients together with five pairs of... more
Early‐onset epileptic encephalopathies (EOEE) are severe neurological disorders characterized by frequent seizures accompanied by developmental regression or retardation. Whole‐exome sequencing of 12 patients together with five pairs of parents and subsequent Sanger sequencing in additional 328 EOEE patients identified two de novo frameshift and one missense mutations in SLC35A2 at Xp11.23, respectively. The three patients are all females. X‐inactivation analysis of blood leukocyte DNA and mRNA analysis using lymphoblastoid cells derived from two patients with a frameshift mutation indicated that only the wild‐type SLC35A2 allele was expressed in these cell types, at least in part likely as a consequence of skewed X‐inactivation. SLC35A2 encodes a UDP‐galactose transporter (UGT), which selectively supplies UDP‐galactose from the cytosol to the Golgi lumen. Transient expression experiments revealed that the missense mutant protein was correctly localized in the Golgi apparatus. In co...
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Vanishing white matter disease (VWM)/childhood ataxia with central hypomyelination (CACH) is an autosomal recessive leukoencephalopathy caused by mutations in one of five genes, EIF2B1-5, encoding the 5 subunits of eukaryotic translation... more
Vanishing white matter disease (VWM)/childhood ataxia with central hypomyelination (CACH) is an autosomal recessive leukoencephalopathy caused by mutations in one of five genes, EIF2B1-5, encoding the 5 subunits of eukaryotic translation initiation factor 2B (eIF2B). The classical phenotype is characterized by early childhood onset and chronic progressive neurological deterioration with cerebellar ataxia, spasticity, optic atrophy and epilepsy. However, the onset of disease varies from antenatal period to adulthood. Cree leukoencephalopathy (CLE) is a severe variant of VWM and caused by a homozygous mutation (R195H) in the EIF2B5 gene. The patient reported in this study developed lethargy, vomiting and seizure 3days after an oral poliovirus vaccination at the age of 4months. She presented with rapid neurological deterioration within a month of onset. Brain MRI showed abnormal white matter intensity. Whole-exome sequencing identified two heterozygous mutations in the EIF2B5 gene: a known mutation, c.584G>A (R195H, which is homozygous in CLE), and a novel mutation, c.1223T>C (I408T, which resides in the "I-patch"). Mutations in the "I-patch" encoded region of eIF2Bε may be related to an early-infantile onset phenotype. This patient exhibits an early-infantile onset and progressive disease course resembling CLE, suggesting a severe functional disruption of eIF2Bε caused by R195H as well as by I408T mutations.
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The I93M mutation in ubiquitin carboxyl-terminal hydrolase L1 (UCH-L1) was reported in one German family with autosomal dominant... more
The I93M mutation in ubiquitin carboxyl-terminal hydrolase L1 (UCH-L1) was reported in one German family with autosomal dominant Parkinson's disease (PD). The causative role of the mutation has, however, been questioned. We generated transgenic (Tg) mice carrying human UCHL1 under control of the PDGF-B promoter; two independent lines were generated with the I93M mutation (a high- and low-expressing line) and one line with wild-type human UCH-L1. We found a significant reduction in the dopaminergic neurons in the substantia nigra and the dopamine content in the striatum in the high-expressing I93M Tg mice as compared with non-Tg mice at 20 weeks of age. Although these changes were absent in the low-expressing I93M Tg mice, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) treatment profoundly reduced dopaminergic neurons in this line as compared with wild-type Tg or non-Tg mice. Abnormal neuropathologies were also observed, such as silver staining-positive argyrophilic grains in the perikarya of degenerating dopaminergic neurons, in I93M Tg mice. The midbrains of I93M Tg mice contained increased amounts of insoluble UCH-L1 as compared with those of non-Tg mice, perhaps resulting in a toxic gain of function. Collectively, our data represent in vivo evidence that expression of UCHL1(I93M) leads to the degeneration of dopaminergic neurons.
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Pelizaeus-Merzbacher disease (PMD) is a form of X-linked leukodystrophy caused by mutations in the proteolipid protein 1 (PLP1) gene. Although PLP1 proteins with missense mutations have been shown to accumulate in the rough endoplasmic... more
Pelizaeus-Merzbacher disease (PMD) is a form of X-linked leukodystrophy caused by mutations in the proteolipid protein 1 (PLP1) gene. Although PLP1 proteins with missense mutations have been shown to accumulate in the rough endoplasmic reticulum (ER) in disease model animals and cell lines transfected with mutant PLP1 genes, the exact pathogenetic mechanism of PMD has not previously been clarified. In this study, we established induced pluripotent stem cells (iPSCs) from two PMD patients carrying missense mutation and differentiated them into oligodendrocytes in vitro. In the PMD iPSC-derived oligodendrocytes, mislocalization of mutant PLP1 proteins to the ER and an association between increased susceptibility to ER stress and increased numbers of apoptotic oligodendrocytes were observed. Moreover, electron microscopic analysis demonstrated drastically reduced myelin formation accompanied by abnormal ER morphology. Thus, this study demonstrates the involvement of ER stress in pathog...
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Determining the relationship between clinical phenotype and genotype in genetic diseases is important in clinical practice. In general, frameshift mutations are expected to produce premature termination codons, leading to production of... more
Determining the relationship between clinical phenotype and genotype in genetic diseases is important in clinical practice. In general, frameshift mutations are expected to produce premature termination codons, leading to production of mutant transcripts destined for degradation by nonsense-mediated decay. In X-linked recessive diseases, male patients with frameshift mutations typically have a severe or even lethal phenotype. We report a case of a 17-month-old boy with Menkes disease (NIM #309400), an X-linked recessive copper metabolism disorder caused by mutations in the ATP7A copper transporter gene. He exhibited an unexpectedly late onset and experienced milder symptoms. His genomic DNA showed a de novo two-nucleotide deletion in exon 4 of ATP7A, predicting a translational frameshift and premature stop codon, and a classic severe phenotype. Characterization of his ATP7A mRNA showed no abnormal splicing. We speculate that translation reinitiation could occur downstream to the premature termination codon and produce a partially functional ATP7A protein. Study of the child's fibroblasts found no evidence of translation reinitiation; however, the possibility remains that this phenomenon occurred in neural tissues and influenced the clinical phenotype.
Research Interests: Pediatric Neurology, Humans, Male, Infant, Phenotype, and 3 moreBase Sequence, Neurosciences, and Age of Onset
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Research Interests: Aging, Neurochemistry, Proteomics, Oxidative Stress, Molecular Mechanics, and 19 moreMice, Animals, Sensory Neuron, Protein Aggregation, Central Nervous System, Proteins, Enzyme, Peripheral Neuropathy, Axonal Degeneration, Ubiquitin Proteasome System, Protein Expression, Neurodegenerative Disease, Sciatic Nerve, Biological markers, Gel electrophoresis, Two-Dimensional Gel Electrophoresis, Axons, Neurosciences, and Aldehydes
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PLP1 amino acid substitutions cause accumulation of misfolded protein and induce endoplasmic reticulum (ER) stress, causing Pelizaeus-Merzbacher disease (PMD), a hypomyelinating disorder of the central nerve system. Currently no effective... more
PLP1 amino acid substitutions cause accumulation of misfolded protein and induce endoplasmic reticulum (ER) stress, causing Pelizaeus-Merzbacher disease (PMD), a hypomyelinating disorder of the central nerve system. Currently no effective therapy is available for PMD. Promoted by its curative effects in other genetic disease models caused by similar molecular mechanisms, we tested if curcumin, a dietary compound, can rescue the lethal phenotype of a PMD mouse model (myelin synthesis deficient, msd). Curcumin was administered orally to myelin synthesis deficit (msd) mice at 180 mg·kg(-1)·day(-1) from the postnatal day 3. We evaluated general and motor status, changes in myelination and apoptosis of oligodendrocytes by neuropathological and biochemical examination, and transcription levels for ER-related molecules. We also examined the pharmacological effect of curcumin in cell culture system. Oral curcumin treatment resulted in 25% longer survival (p<0.01). In addition, oligodendrocytes undergoing apoptosis were reduced in number (p<0.05). However, no apparent improvement in motor function, neurological phenotype, and myelin formation was observed. Curcumin treatment did not change the expression of ER stress markers and subcellular localization of the mutant protein in vitro and/or in vivo. Curcumin partially mitigated the clinical and pathological phenotype of msd mice, although molecular mechanisms underlying this curative effect are yet undetermined. Nonetheless, curcumin may serve as a potential therapeutic compound for PMD caused by PLP1 point mutations.
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Research Interests: Electroencephalography, Japan, Magnetic Resonance Spectroscopy, Humans, MR spectroscopy, and 12 moreFemale, Inborn errors of metabolism, Magnetic Resonance, Central Nervous System, Enzyme, Clinical Sciences, Family Health, Time Factors, Basal ganglia, X ray Computed Tomography, Chromosomes, and Protons
Nicotinic acetylcholine receptors (nAChRs) have been implicated in a number of neurological disorders. 5-Iodo-3-[2(S)-2-azetidinylmethoxy]pyridine (5-I-A-85380) is a novel nAChR marker, binding predominantly to the alpha4beta2 subtype.... more
Nicotinic acetylcholine receptors (nAChRs) have been implicated in a number of neurological disorders. 5-Iodo-3-[2(S)-2-azetidinylmethoxy]pyridine (5-I-A-85380) is a novel nAChR marker, binding predominantly to the alpha4beta2 subtype. This in vitro autoradiography study describes the distribution of 5-[(125)I]-A-85380 binding in post-mortem brain tissue from normal elderly individuals and from cases with age-associated dementias of both neurodegenerative and vascular types. The binding distribution of 5-[(125)I]-A-85380 in normal brain tissue was found to be consistent with the reported distribution of other high-affinity nicotinic ligands. In addition to high thalamic and moderate striatal and temporal cortex density, moderate 5-[(125)I]-A-85380 binding was also seen in white matter tracts in cingulate, occipital, and temporal areas, indicating the presence of nAChRs along nerve fiber tracts, which has not been reported in other high-affinity nicotinic agonist distribution studies. In Parkinson's disease (PD), loss of striatal 5-[(125)I]-A-85380 binding closely parallels the loss of nigrostriatal dopaminergic markers previously observed. In dementia with Lewy bodies (DLB) reduced striatal 5-[(125)I]-A-85380 binding density, comparable to that in PD, may be a marker of early degeneration in nigrostriatal inputs, while in Alzheimer's disease (AD) reduced striatal 5-[(125)I]-A-85380 binding could be related to reduced cortical inputs. The reductions of nAChRs seen in AD, DLB, and PD were not apparent in vascular dementia (VaD). In conclusion, 5-I-A-85380 is clearly a useful ligand for both in vitro and in vivo single photon emission tomography human studies investigating disease symptoms and progression, response to acetylcholinesterase-inhibiting drugs and in differentiating primary degenerative dementia from VaD.
Research Interests: Zoology, Radiochemistry, Neuropsychopharmacology, Immunohistochemistry, Western blotting, and 28 moreHumans, Vascular dementia, Female, Animals, Spinal Cord, Male, Acetylcholinesterase, Nicotinic Acetylcholine Receptors, The, Medical Physiology, Temporal Cortex, Aged, White matter, Rats, Single Photon Emission Computed Tomography, Analysis of Variance, Degeneration, Pyridines, Autoradiography, Neural pathways, Rabbits, Comparative Neurology, Alzheimer Disease, Neurosciences, Dementia With Lewy Bodies, Parkinson Disease, Brain Diseases, and Case Control Studies
Loss-of-function mutations of the parkin gene causes an autosomal recessive juvenile-onset form of... more
Loss-of-function mutations of the parkin gene causes an autosomal recessive juvenile-onset form of Parkinson's disease (AR-JP). Parkin was shown to function as a RING-type E3 ubiquitin protein ligase. However, the function of parkin in neuronal cells remains elusive. Here, we show that expression of parkin-potentiated adenosine triphosphate (ATP)-induced currents that result from activation of the P2X receptors which are widely distributed in the brain and involved in neurotransmission. ATP-induced inward currents were measured in mock-, wild-type or mutant (T415N)-parkin-transfected PC12 cells under the conventional whole-cell patch clamp configuration. The amplitude of ATP-induced currents was significantly greater in wild-type parkin-transfected cells. However, the immunocytochemical study showed no apparent increase in the number of P2X receptors or in ubiquitin levels. The increased currents were attenuated by inhibition of cAMP-dependent protein kinase (PKA) but not protein kinase C (PKC) or Ca2+ and calmodulin-dependent protein kinase (CaMKII). ATP-induced currents were also regulated by phosphatases and cyclin-dependent protein kinase 5 (CDK5) via dopamine and cyclic AMP-regulated phosphoprotein (DARPP-32), though the phosphorylation at Thr-34 and Thr-75 were unchanged or rather attenuated. We also tried to investigate the effect of alpha-synuclein, a substrate of parkin and also forming Lysine 63-linked multiubiquitin chains. Expression of alpha-synuclein did not affect the amplitude of ATP-induced currents. Our finding provides the evidence for a relationship between parkin and a neurotransmitter receptor, suggesting that parkin may play an important role in synaptic activity.
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... Chiaki Kawanishi 1,* ,; Hitoshi Osaka 2 ,; Ken Inoue 1 ,; Hideki Onishi 1 ,; Yoshiteru Yamada 1 ,; Naoya Sugiyama 1 ,; Kyoko Suzuki 1 ,; Tokiji Hanihara 1 ,; ... 1 Department of Psychiatry,Yokohama City University School of Medicine,... more
... Chiaki Kawanishi 1,* ,; Hitoshi Osaka 2 ,; Ken Inoue 1 ,; Hideki Onishi 1 ,; Yoshiteru Yamada 1 ,; Naoya Sugiyama 1 ,; Kyoko Suzuki 1 ,; Tokiji Hanihara 1 ,; ... 1 Department of Psychiatry,Yokohama City University School of Medicine, Yokohama 236, Japan; Fax: 81-45-783-2540. ...
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We found a novel acceptor splice site mutation in the invariant AG of intron 6 of alpha-galactosidase A (alpha-Gal A) gene (IVS6-1G->A) in a patient with Fabry disease by sequencing of genomic DNA. Sequencing of RT-PCR revealed the... more
We found a novel acceptor splice site mutation in the invariant AG of intron 6 of alpha-galactosidase A (alpha-Gal A) gene (IVS6-1G->A) in a patient with Fabry disease by sequencing of genomic DNA. Sequencing of RT-PCR revealed the deletion of first base pair (c909del) of exon 7 in mRNA and a frameshift resulting in premature termination. This mutation gives rise to a rare aberrant splicing (Simultaneous 3' destruction and 3' creation).
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... Chiaki Kawanishi 1,3,* ,; Hitoshi Osaka 2 ,; Kenji Owa 2 ,; Ken Inoue 2 ,; Tomohiro Miyakawa 1 ,; Hideki Onishi 1 ,; Yoshiteru Yamada 1 ,; Kyoko Suzuki 1 ,; ... Author Information. 1 Department of Psychiatry, Yokohama City University,... more
... Chiaki Kawanishi 1,3,* ,; Hitoshi Osaka 2 ,; Kenji Owa 2 ,; Ken Inoue 2 ,; Tomohiro Miyakawa 1 ,; Hideki Onishi 1 ,; Yoshiteru Yamada 1 ,; Kyoko Suzuki 1 ,; ... Author Information. 1 Department of Psychiatry, Yokohama City University, Yokohama 236, Japan; Fax: 81-45-783-2540. 2 ...
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... Chiaki Kawanishi 1,* ,; Naoya Sugiyama 1 ,; Hitoshi Osaka 2 ,; Ken Inoue 1 ,; Kyoko Suzuki 1 ,; Hideki Onishi 1 ,; Yoshiteru Yamada 1 ,; Atsuo Nezu 2 ,; Seiji Kimura 2 ,; Kenji Kosaka 1. ... Author Information. 1 Department of... more
... Chiaki Kawanishi 1,* ,; Naoya Sugiyama 1 ,; Hitoshi Osaka 2 ,; Ken Inoue 1 ,; Kyoko Suzuki 1 ,; Hideki Onishi 1 ,; Yoshiteru Yamada 1 ,; Atsuo Nezu 2 ,; Seiji Kimura 2 ,; Kenji Kosaka 1. ... Author Information. 1 Department of Psychiatry, Yokohama City University, Yokohama 236, Japan ...
Research Interests: Genetics, Human, Humans, Child, Mutation, and 3 moreMale, Polymerase Chain Reaction, and Clinical Sciences
Mammalian neuronal cells abundantly express a deubiquitylating enzyme, ubiquitin carboxy-terminal hydrolase 1 (UCH L1). Mutations in UCH L1 are linked to... more
Mammalian neuronal cells abundantly express a deubiquitylating enzyme, ubiquitin carboxy-terminal hydrolase 1 (UCH L1). Mutations in UCH L1 are linked to Parkinson's disease as well as gracile axonal dystrophy (gad) in mice. In contrast to the UCH L3 isozyme that is universally expressed in all tissues, UCH L1 is expressed exclusively in neurons and testis/ovary. We found that UCH L1 associates and colocalizes with monoubiquitin and elongates ubiquitin half-life. The gad mouse, in which the function of UCH L1 is lost, exhibited a reduced level of monoubiquitin in neurons. In contrast, overexpression of UCH L1 caused an increase in the level of ubiquitin in both cultured cells and mice. These data suggest that UCH L1, with avidity and affinity for ubiquitin, insures ubiquitin stability within neurons. This study is the first to show the function of UCH L1 in vivo.
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Research Interests: Aging, Immunohistochemistry, Drosophila melanogaster, Apoptosis, Transgenic Mice, and 21 moreSignal Transduction, Caspases, Ubiquitin, Mitosis, Cell Differentiation, Spermatogenesis, Mice, Animals, Male, Cell Death, Male Infertility, Medical Physiology, Phenotype, Sertoli cells, Eye, Caspase, Cell Proliferation, Transgenic Mouse Technology, Vimentin, Biochemistry and cell biology, and Down-Regulation
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Creatine transporter deficiency (CTD) is an example of X-linked intellectual disability syndromes, caused by mutations in SLC6A8 on Xq28. Although this is the second most frequent genetic cause of intellectual disabilities in Europe or... more
Creatine transporter deficiency (CTD) is an example of X-linked intellectual disability syndromes, caused by mutations in SLC6A8 on Xq28. Although this is the second most frequent genetic cause of intellectual disabilities in Europe or America after Fragile X syndrome, information on the morbidity of this disease is limited in Japan. Using the HPLC screening method we have established recently, we examined samples of urine of 105 patients (73 males and 32 females) with developmental disabilities at our medical center. And we have found a family with three ID boys with a novel missense mutation in SLC6A8. This is the second report of a Japanese family case of CTD. A systematic diagnostic system of this syndrome should be established in Japan to enable us to estimate its frequency and treatment.