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M Nishizawa

Publications and source records attributed to M Nishizawa.

At least 19 recordsLinked to original sources
PubMed2006

Anisotropy and corotation of galactic cosmic rays.

The intensity of Galactic cosmic rays is nearly isotropic because of the influence of magnetic fields in the Milky Way. Here, we present two-dimensional high-precision anisotropy measurement for energies from a few to several hundred teraelectronvolts (TeV), using the large data sample of the Tibet Air Shower Arrays. Besides revealing finer details of the known anisotropies, a new component of Galactic cosmic ray anisotropy in sidereal time is uncovered around the Cygnus region direction. For cosmic-ray energies up to a few hundred TeV, all components of anisotropies fade away, showing a corotation of Galactic cosmic rays with the local Galactic magnetic environment. These results have broad implications for a comprehensive understanding of cosmic rays, supernovae, magnetic fields, and heliospheric and Galactic dynamic environments.

Journal Article↗
PubMed2006

New HSN2 mutation in Japanese patient with hereditary sensory and autonomic neuropathy type 2.

The authors report a Japanese patient with hereditary sensory and autonomic neuropathy type 2 (HSAN2) who has a new mutation of the HSN2 gene. The pathologic findings of the patient matched those of Canadian patients. They identified a homozygous 1134-1135 ins T mutation, resulting in a frameshift, and the subsequent premature stop codon at residue 378. These observations support the hypothesis that HSN2 is a causative gene for HSAN2.

Adult↗
PubMed2004

Observation by an air-shower array in Tibet of the multi-TeV cosmic-ray anisotropy due to terrestrial orbital motion around the Sun.

We report on the solar diurnal variation of the galactic cosmic-ray intensity observed by the Tibet III air shower array during the period from 1999 to 2003. In the higher-energy event samples (12 and 6.2 TeV), the variations are fairly consistent with the Compton-Getting anisotropy due to the terrestrial orbital motion around the Sun, while the variation in the lower-energy event sample (4.0 TeV) is inconsistent with this anisotropy. This suggests an additional anisotropy superposed at the multi-TeV energies, e.g., the solar modulation effect. This is the highest-precision measurement of the Compton-Getting anisotropy ever made.

Journal Article↗
PubMed2004

Identification of a SACS gene missense mutation in ARSACS.

The authors describe two patients in a Japanese family with autosomal recessive spastic ataxia of Charlevoix-Saguenay. They presented early onset spastic ataxia, sensorimotor neuropathy, nystagmus, slurred speech, and hypermyelinated retinal nerve fibers. The authors identified a homozygous missense mutation (T7492C) in the SACS gene, which resulted in the substitution of arginine for tryptophan at amino acid residue 2498 (W2498R).

Adult↗
PubMed2003

Dysferlin mutations in Japanese Miyoshi myopathy: relationship to phenotype.

OBJECTIVE: To study dysferlin gene mutations and genotype-phenotype correlations in Japanese patients with Miyoshi myopathy (MM). BACKGROUND: MM is an autosomal recessive distal muscular dystrophy that arises from mutations in the dysferlin gene. This gene is also mutated in families with limb girdle muscular dystrophy 2B. METHODS: The authors examined 25 Japanese patients with MM. Genomic DNA was extracted from the peripheral lymphocytes of the patients. The PCR products of each of 55 exons were screened by single strand conformation polymorphism or direct sequencing from the PCR fragments. RESULTS: The authors identified 16 different mutations in 20 patients with MM; 10 were novel. Mutations in Japanese patients are distributed along the entire length of the gene. CONCLUSIONS: Four mutations (C1939G, G3370T, 3746delG, and 4870delT) are relatively more prevalent in this population, accounting for 60% of the mutations in this study. This study revealed that the G3370T mutation was associated with milder forms of MM and the G3510A mutation was associated with a more severe form.

Adult↗
PubMed2002

Early-onset ataxia with ocular motor apraxia and hypoalbuminemia: the aprataxin gene mutations.

BACKGROUND: Early-onset ataxia with hypoalbuminemia is regarded as a variant form of Friedreich ataxia in Japan. Early-onset ataxia with hypoalbuminemia and ataxia with ocular motor apraxia have been considered as the same clinical entity because of the recent identification of a common mutation in the aprataxin gene. A new clinical entity named early-onset ataxia with ocular motor apraxia and hypoalbuminemia (EAOH) has been proposed to explain these two diseases. OBJECTIVE: To disclose the clinical features of EAOH and to identify the mutations in the aprataxin gene in six patients in four Japanese families with EAOH. METHODS: The clinical features, laboratory findings, sural nerve biopsy results, and brain MRI or CT findings for these patients were evaluated, and molecular analysis was performed, which involved sequencing of the aprataxin gene directly or use of the subcloning method. RESULTS: Cerebellar ataxia and peripheral neuropathy were noted in all six patients. Ocular motor apraxia was observed in five patients; two of these patients had obvious head thrust. Choreiform movements of the limbs and mental deterioration were observed in five patients. Although foot deformity was noted in five patients, kyphoscoliosis was noted only in one patient. In all patients, hypoalbuminemia and hypercholesterolemia were evident, and brain MRI or CT showed marked cerebellar atrophy. Nerve biopsy revealed depletion of large myelinated fibers in three of the five patients examined. Molecular analysis of the aprataxin gene revealed an insertion mutation (insT at nt167) and two missense mutations (A-to-G transition at nt80 and C-to-T transition at nt95, the former being novel). CONCLUSION: We found clinical heterogeneity in the patients with EAOH in this study. With the disease course, the choreiform movements tended to reduce in degree, and hypoalbuminemia became evident. Molecular analysis identified one insertion and two missense mutations including a novel missense one, which was located at a highly conserved amino acid residue in the aprataxin gene product.

Adult↗
PubMed2002

A Japanese SPG4 family with a novel missense mutation of the SPG4 gene: intrafamilial variability in age at onset and clinical severity.

OBJECTIVES: We report the results of clinical and genetic studies on a Japanese SPG4 family. MATERIAL AND METHODS: Family N included eight patients in four generations with autosomal dominant transmission. We performed neurological and molecular analyses on the SPG4 gene in the family members comprising three patients, 12 at-risk individuals, and three normal spouses. RESULTS: The three patients showed pure spastic paraplegia, two of them exhibiting a decrease in vibration sense. There was marked intrafamilial variability in age at onset and clinical severity in the present family. On molecular analysis, a novel missense mutation (nt1579 C-->T) in exon 12 of the SPG4 gene was found in the three patients, three probably affected, and an asymptomatic carrier. CONCLUSION: The present SPG4 family, which was shown to have a novel SPG4 mutation, exhibited marked variability in the clinical features, indicating the participation of additional factors in the phenotypic appearance of this family.

Adenosine Triphosphatases↗
PubMed2001

Isolation and expression of a Bacillus cereus gene encoding benzil reductase.

Benzil was reduced stereospecifically to (S)-benzoin by Bacillus cereus strain Tim-r01. To isolate the gene responsible for asymmetric reduction, we constructed a library consisting of Escherichia coli clones that harbored plasmids expressing Bacillus cereus genes. The library was screened using the halo formation assay, and one clone showed benzil reduction to (S)-benzoin. Thus, this clone seemed to carry a plasmid encoding a Bacillus cereus benzil reductase. The deduced amino acid sequence had marked homologies to the Bacillus subtilis yueD protein (41% identity), the yeast open reading frame YIR036C protein (31%), and the mammalian sepiapterin reductases (28% to 30%), suggesting that benzil reductase is a novel short-chain de-hydrogenases/ reductase.

Alcohol Oxidoreductases↗
PubMed2001

Keratin attenuates tumor necrosis factor-induced cytotoxicity through association with TRADD.

Keratin 8 and 18 (K8/18) are the major components of intermediate filament (IF) proteins of simple or single-layered epithelia. Recent data show that normal and malignant epithelial cells deficient in K8/18 are nearly 100 times more sensitive to tumor necrosis factor (TNF)-induced cell death. We have now identified human TNF receptor type 1 (TNFR1)-associated death domain protein (TRADD) to be the K18-interacting protein. Among IF proteins tested in two-hybrid systems, TRADD specifically bound K18 and K14, type I (acidic) keratins. The COOH-terminal region of TRADD interacted with the coil Ia of the rod domain of K18. Endogenous TRADD coimmunoprecipitated with K18, and colocalized with K8/18 filaments in human mammary epithelial cells. Overexpression of the NH2 terminus (amino acids 1-270) of K18 containing the TRADD-binding domain as well as overexpression of K8/18 in SW13 cells, which are devoid of keratins, rendered the cells more resistant to killing by TNF. We also showed that overexpressed NH2 termini of K18 and K8/18 were associated with endogenous TRADD in SW13 cells, resulting in the inhibition of caspase-8 activation. These results indicate that K18 may sequester TRADD to attenuate interactions between TRADD and activated TNFR1 and moderate TNF-induced apoptosis in simple epithelial cells.

Aclarubicin↗
PubMed2001

Negative regulation of transcription by the yeast global transcription factors, Gal11 and Sin4.

Gal11 and Sin4 proteins are yeast global transcription factors that regulate transcription of a variety of genes, both positively and negatively. Gal11, in a major part, functions in the activation of transcription, whereas Sin4 has an opposite role, yet they are reported to be present as a complex in the so-called RNA polymerase II holoenzyme. To reveal howthese auxiliary factors participate in switching transcription on and off, a complex formation between Gal11 and Sin4 and its effect on the negative regulation of transcription were studied. Using an artificial promoter that is negatively regulated by Gal11, it was shown that the presence of Sin4 or Pgd1/Hrs1/Med3 was required for Gal11 to repress both basal and activated transcription. Genetic and biochemical studies using a temperature-sensitive Gal11 mutant showed that the amino acid region 866-910 essential for Gal11 function was also important for repression of transcription and a complex formation with Sin4. Analysis with dam methylase accessibility to the promoter region suggested that nucleosome structure may be involved in negative regulation. Based on these results, possible mechanisms by which a mediator subcomplex regulates transcription is discussed.

Blotting, Western↗
PubMed2001

Maf and Jun nuclear oncoproteins share downstream target genes for inducing cell transformation.

The Maf oncoprotein is a basic leucine zipper (bZip)-bearing transcriptional activator that recognizes the Maf recognition element (MARE) DNA sequence. In this study, we investigated the role of Maf's transactivation function in cell transformation. Replacement of the conserved amino terminus transactivator domain of Maf by a heterologous and stronger transactivator domain (the acidic transactivator domain of VP16) resulted in enhanced transformation of chicken embryo fibroblast cells. In contrast, the fusing of a transcriptional repressor domain (Sin3 interaction domain of Mxi1) with the whole Maf protein masked the transactivator function of Maf, which in turn inhibited its transforming activity. Furthermore, the leucine zipper domain of Maf, which defines its dimer-forming specificity, was exchangeable with that of GCN4 yeast protein in terms of its transactivating and cell transforming activities. Thus, heterodimer formation with other bZip factors is not required for Maf's ability to transform. These results together suggest that transactivation through MARE is necessary for Maf-induced transformation and that there exist downstream target gene(s) for transformation. Since the MARE sequence overlaps with the recognition element of another bZip oncoprotein Jun, we assessed whether Jun and Maf induce cell transformation through activating the same genes. We thus constructed a mutated version of Jun that has a GCN4 leucine zipper and lacks the transactivator domain. This mutant repressed the cell transformation not only by Jun but also by Maf. Thus, Maf and Jun share downstream target gene(s) that are involved in cell transformation.

Animals↗
PubMed2001

Optical anisotropy of oxidized Si(001) surfaces and its oscillation in the layer-by-layer oxidation process.

Reflectance-difference (RD) measurements for the oxidation of single-domain (2x1)-reconstructed Si(001) surfaces show that the polarity of the interface-induced optical anisotropy is reversed repeatedly with increasing oxide thickness. The oscillation of the RD amplitude, which we show is due to layer-by-layer progression of the oxidation, has allowed us to count the number of oxidized Si layers in situ during oxidation. The origins of the observed spectral line shape are discussed.

Journal Article↗
PubMed2001

Induction of cellular antioxidative stress genes through heterodimeric transcription factor Nrf2/small Maf by antirheumatic gold(I) compounds.

Gold(I)-containing compounds have long been used in the treatment of rheumatoid arthritis (RA), but the molecular mechanism of their action has remained largely unknown. In this paper we have demonstrated that gold(I) drugs selectively activate the DNA binding of a heterodimer consisting of the basic-leucine zipper transcription factors Nrf2 and small Maf. Once bound to its recognition DNA sequence termed antioxidant-responsive element or Maf-recognition element, Nrf2/small Maf induces a set of antioxidative stress genes, including heme oxygenase-1 and gamma-glutamylcysteine synthetase, whose products have been demonstrated to contribute to the scavenging of reactive oxygen species and to exhibit anti-inflammatory effects. Our findings suggest that stimulation of antioxidative stress response through activation of Nrf2/small Maf may be a pharmacologically important part of the actions of gold(I) drugs for the treatment of rheumatoid arthritis. Alternatively, activation of Nrf2/small Maf may be a protective response of cells against toxic effects of the drugs.

Antirheumatic Agents↗
PubMed2001

Choreiform movements in spinocerebellar ataxia type 1.

We describe the unusual case of a 51-year-old woman with spinocerebellar ataxia type 1 (SCA1) who showed choreiform movements in addition to cerebellar ataxia. To date, extrapyramidal signs including involuntary movements have been rarely reported in SCA1. Surface electromyogram in our patient revealed grouped discharges whose duration was longer than that of chorea observed in HD, indicating that the involuntary movements represented choreoathetosis rather than pure chorea. These choreiform movements have not been seen in non-hereditary spinocerebellar ataxia. Therefore, if "sporadic" cases of cerebellar ataxia show such movements, the possibility of genetic origin of the ataxia is high and a surveillance of various forms of hereditary spinocerebellar ataxia including SCA1 is required.

Cerebellum↗