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Biomedical subjects

S Ozawa

Publications and source records attributed to S Ozawa.

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

Serum concentrations of high-mobility group box chromosomal protein 1 before and after exposure to the surgical stress of thoracic esophagectomy: a predictor of clinical course after surgery?

High-mobility group box chromosomal protein 1 (HMGB-1) has recently been shown as an important late mediator of endotoxin shock, intra-abdominal sepsis, and acute lung injury. However, its role in the systemic inflammatory response syndrome after major surgical stress, which may lead to multiple organ dysfunction syndrome, has not been thoroughly investigated. We hypothesized that serum HMGB-1 participates in the pathogenesis of postoperative organ system dysfunction after exposure to major surgical stress. A prospective clinical study was performed to consecutive patients (n = 24) with carcinoma of the thoracic esophagus who underwent transthoracic esophagectomy with three field lymph node resection between 1998 and 2003 at Keio University Hospital, Japan. Serum HMGB-1 concentrations were measured by enzyme-linked immunosorbent assay. Preoperative serum HMGB-1 levels correlated with postoperative duration of SIRS, mechanical ventilation, and intensive care unit stay. Three of the 24 patients had serious postoperative complications: sepsis in two, and acute lung injury in one. Serum HMGB-1 levels in patients without complications increased within the first 24 h postoperatively, remained high during postoperative days 2-3, and then decreased gradually by postoperative day 7. In patients with serious complications, serum HMGB-1 was significantly higher than that found in patients without postoperative complications at every time point except postoperative day 2. Preoperative serum HMGB-1 concentration seems to be an important predictor of the postoperative clinical course. Transthoracic esophagectomy induces an increase in HMGB-1 in serum even in patients without complications. Postoperative serum HMGB-1 concentrations were higher in patients who developed complications, and may be a predictive marker for complications in this setting.

Enzyme-Linked Immunosorbent Assay↗
PubMed2006

Genetic variations and haplotype structures of the ABCB1 gene in a Japanese population: an expanded haplotype block covering the distal promoter region, and associated ethnic differences.

As functional ABCB1 haplotypes were recently reported in the promoter region of the gene, we resequenced the ABCB1 distal promoter region, along with other regions (the enhancer and proximal promoter regions, and all 28 exons), in a total of 533 Japanese subjects. Linkage disequilibrium (LD) analysis based on 92 genetic variations revealed 4 LD blocks with the same make up as previously described (Blocks -1, 1, 2 and 3), except that Block 1 was expanded to include the distal promoter region, and that a new linkage between polymorphisms -1,789G>A in the distal promoter region and IVS5 + 123A>G in intron 5 was identified. We re-assigned Block 1 haplotypes, and added novel haplotypes to the other 3 blocks. The reported promoter haplotypes were further classified into several types according to tagging variations within Block 1 coding or intronic regions. Our current data reconfirm the haplotype profiles of the other three blocks, add more detailed information on functionally-important haplotypes in Block 1 and 2 in the Japanese population, and identified differences in haplotype profiles between ethnic groups. Our updated analysis of ABCB1 haplotype blocks will assist pharmacogenetic and disease-association studies carried out using Asian subjects.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed2005

Genetic polymorphisms and haplotypes of the human cardiac sodium channel alpha subunit gene (SCN5A) in Japanese and their association with arrhythmia.

Genetic variations in cardiac ion channels have been implicated not only as the causes of inherited arrhythmic syndromes, but also as genetic risk factors for some acquired arrhythmias. To elucidate the potential roles of genetic polymorphisms of the alpha subunit of the voltage-gated sodium channel type V (SCN5A) in cardiac rhythm disturbance, the entire SCN5A coding exons and their flanking introns were sequenced in 166 Japanese arrhythmic patients and 232 healthy controls. We detected 69 genetic variations, including 54 novel ones. Out of the 12 novel nonsynonymous single nucleotide polymorphisms (SNPs), p.Leu1988Arg was found at a frequency of 0.015. The other 11 SNPs were rare (0.001), with 6 found in arrhythmic patients and 5 in healthy controls. The frequency of a novel intronic SNP, c.703+130G>A, was significantly higher in the patients than in the controls, suggesting this SNP is associated with an unknown risk factor for arrhythmia. Following linkage disequilibrium analysis, the haplotype structure of SCN5A was inferred using high-frequency SNPs. The frequency of the haplotype harbouring both p.Leu1988Arg and the common SNP p.His558Arg (haplotype GG) was significantly lower in the patients than in the controls. This finding suggests that this haplotype (GG) might have been positively selected in the controls because of its protective effect against arrhythmias. This study provides fundamental information necessary to elucidate the effect of genetic variations in SCN5A on channel function and cardiac rhythm in Japanese, and probably in the Asian population.

Arrhythmias, Cardiac↗
PubMed2005

Alterations of p53, cyclin D1 and pRB expression in the carcinogenesis of esophageal squamous cell carcinoma.

Many molecular alterations occur in esophageal carcinogenesis; however, little is known about the molecular genetic events responsible for the development of carcinoma. We investigated the expression of ki67, p53, cyclin D1 and pRB in 105 biopsy specimens using immunohistochemistry from iodine unstained lesions as indicators of carcinogenesis of the esophagus. Also, the genetic alternation of esophageal dysplasia from patients with accompanying esophageal squamous cell carcinoma (ESCC) was examined to study the evidence for field carcinogenesis in the esophagus. The expression of p53, cyclin D1 and pRB was detected in 31, 0 and 51.7% respectively of mild dysplasia; 40, 0 and 70% of moderate dysplasia; 40, 20 and 70% of severe dysplasia; and 48, 32 and 80% of carcinoma specimens. p53 expression was significantly increased in mild dysplasia, whereas cyclin D1 and pRB expression were significantly increased in carcinoma as compared to both normal epithelium and esophagitis. The ki67 LI and the rate of p53 expression were significantly higher in dysplasia with ESCC than in dysplasia without ESCC. Ki67, p53, cyclin D1 and pRB expression may be useful biomarkers for assessing the risk of developing esophageal cancer. Dysplasia observed at screening for secondary lesions has a highly malignant potential and careful follow-up studies are required.

Carcinoma, Squamous Cell↗
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

Characterization of 4-O-methyl-ascochlorin-induced apoptosis in comparison with typical apoptotic inducers in human leukemia cell lines.

Apoptosis can be induced by various stimuli such as the ligands of death receptors, chemotherapeutic drugs and irradiation. It is generally believed that chemotherapeutic drugs induce mitochondrial damage, cytochrome c release and activation of caspase-9, leading to apoptosis. Here, we found that an isoprenoid antibiotic, 4-O-methyl ascochlorin, significantly induces typical apoptotic events in Jurkat cells including the degradation of poly (ADP-ribose) polymerase, DNA fragmentation, activation of caspase-3, -9 and -8, and cytochrome c release from mitochondria. Similar to Fas stimulation, 4-O-methyl ascochlorin but not staurosporine, cycloheximide and actinomycin D, induced apoptosis in SKW6.4 cells, in which apoptosis is strongly dependent on death-inducing signaling-complex. Bcl-2 overexpression in Jurkat cells completely suppressed the apoptosis, but procaspase-9 processing was partially induced. A caspase-8 inhibitor, IETD-fmk, effectively suppressed poly (ADP-ribose) polymerase cleavage and cytochrome c release. However, 4-O-methyl ascochlorin induced apoptosis in Jurkat cells deficient of caspase-8 or Fas-associated death domain protein. These results suggest that 4-O-methyl ascochlorin induces apoptosis through the mechanism distinct from conventional apoptosis inducers.

Adaptor Proteins, Signal Transducing↗
PubMed2003

Non-synonymous single nucleotide alterations in the microsomal epoxide hydrolase gene and their functional effects.

1. By sequencing genomic DNA from 72 established cell lines derived from Japanese individuals, we detected 25 single nucleotide alterations in the microsomal epoxide hydrolase (EPHX1) gene. Of them, five were exonic alterations resulting in amino acid alterations (77C>G, T26S; 128G>C, R43T; 337T>C, Y113H; 416A>G, H139R; 823A>G, T275A). The T26S, R43T, Y113H and H139R substitutions were found at relatively high frequencies and seemed to be polymorphic, and T26S and T275A were novel. 2. To examine the effects of these amino acid alterations on EPHX1 function, EPHX1 cDNA constructs of wild-type and five variants were transfected into COS-1 cells, and their hydrolytic activities for cis-stilbene oxide were determined in vitro. Although all of the transfectants expressed EPHX1 mRNA and protein at similar levels, the variant H139R protein was expressed at a significantly higher level (128% of the wild-type). K(m) values were not significantly different between the wild-type and variants. 3. Increase (140%) in the enzymatic activity (V(max)) of the variant H139R was accompanied by the increased EPHX1 protein level without any significant change in the intrinsic EPHX1 activity. On the other hand, the variant R43T showed increased values for V(max) and clearance (V(max)/K(m)) (around 130%) both on a microsomal protein basis and on a EPHX1 protein basis. 4. These results suggest that R43T as well as H139R increase epoxide hydrolase activity.

Amino Acid Substitution↗
PubMed2002

Gene expression profiling of Ca2+-atpase inhibitor DTBHQ and antigen-stimulated RBL-2H3 mast cells.

OBJECTIVE AND DESIGN: Ca2+ signaling is critical for mast cell activation by antigen stimulation, and we previously described that the signaling can be mimicked by Ca2+-ATPase inhibitors. We therefore investigated the effect of the Ca2+-ATPase inhibitor and antigen stimulation on the gene expression profiles of RBL-2H3 mast cells. MATERIAL: A Ca2+-ATPase inhibitor, 2,5-di(tert-butyl)-1,4-hydroquinone (DTBHQ), an antigen (dinitrophenylated BSA), a high-density oligonucleotide microarray (Affymetrix GeneChip) technique, and a well-characterized rat mast cell line RBL-2H3 were used. TREATMENT: RBL-2H3 cells were activated for 3 h with 10 microM DTBHQ, which increases cytosolic Ca2+ concentration, or 10 microg/ml antigen, which cross-links IgE receptors, and the mRNA expression profiles (8,799 genes) were analyzed with GeneChip arrays (n = 3). METHODS: Expression levels were measured by GeneChip, and the differences were tested by Welch's t-test and P-values less than 0.05 were considered statistically significant. Values are expressed as means +/- SEM. RESULTS: The genes, including MCP-1, GADD45, Relaxin H1, CSF-1, c-jun-oncogene, Pyk-2, NKR-P2 and CREM, were significantly up-regulated by both DTBHQ and antigen stimuli, whereas the genes including interleukin (IL)-3, IL-4, IL-9, IL-13, GADD153, butyrate response factor, and Fas ligand, were up-regulated by DTBHQ alone. On the other hand, the expression of several genes, including GATA-1, were down-regulated by DTBHQ stimulation. CONCLUSIONS: These results suggest 1) that DTBHQ seems to induce proinflammatory responses by stimulating the production of several cytokines through the expression of several transcription factors, 2) that the changes in gene expression profile induced by DTBHQ and by IgE receptor cross-linking in mast cells were almost the same, but many more stress-inducible genes like GADD 153 were up-regulated by the former.

Animals↗
PubMed2002

Sulfation of bisphenol A abolished its estrogenicity based on proliferation and gene expression in human breast cancer MCF-7 cells.

Bisphenol A, an endocrine-disrupting chemical, is widely used in many consumer products. We previously showed the sulfoconjugation of bisphenol A catalyzed by a human thermostable phenol sulfotransferase, ST1A3. The estrogenic potency of bisphenol A sulfate was compared with that of bisphenol A by an E-screen assay using human breast cancer MCF-7 cells. An increase in the expression level of an estrogen-responsive pS2 gene was also examined using MCF-7 cells after exposure to bisphenol A and its sulfate for their estrogenicity. Bisphenol A sulfate did not exhibit estrogenic effects at 0.1 microM (E-screen assay) and 1 mM (pS2 gene expression) compared with bisphenol A, which exhibited the effects at 3 nM (E-screen assay) and 1 microM (pS2 gene expression), respectively. We have therefore evaluated major roles of cytosolic phenol sulfotransferase in the human liver. Bisphenol A sulfation in human liver cytosols was inhibited by more than 90% by p-nitrophenol and quercetin, a typical substrate and specific inhibitor of phenol sulfotransferase, respectively. These results indicated that the estrogenicity of bisphenol A was abolished through its sulfation catalyzed by a human hepatic thermostable phenol sulfotransferase.

Arylsulfotransferase↗
PubMed2002

Ovariectomy hinders the early stage of bone-implant integration: histomorphometric, biomechanical, and molecular analyses.

Postmenopausal osteoporosis is a contributing factor to alveolar bone atrophy associated with tooth loss in the elderly. The use of dental titanium implants has been increasingly adapted to treat these edentulous patients. This study examines whether female gonadal hormone deficiency interferes with the critical integration process between bone and implants. Two types of experimental titanium implants with acid-treated surfaces were placed in the femurs of ovariectomized (ovx) and sham-operated control rats: T-cell implants with a hollow chamber for histomorphometric and steady-state mRNA expression assays, and unthreaded cylindrical implants for biomechanical push-in tests. At week 2, less bone area was found in the ovx-implant group (p = 0.0495) than in the sham-implant group. The implant push-in test showed that the ovx-implant group had approximately half of the withstanding value of the sham-implant group (p = 0.009). However, these differences between the ovx and sham groups became diminished at week 4. Total RNA samples were examined by a reverse transcriptase-polymerase chain reaction assay for col1a1, col3a1, bone sialoprotein (bSP) II, osteonectin, osteopontin, osteocalcin, integrin beta1 and integrin beta3. In untreated bones and in created bone defects without implant placement, ovx did not affect the steady-state levels of the mRNAs tested. When implants were placed, significant upregulation of these genes was observed in the sham-implant group; however, only osteocalcin and integrins were upregulated in the ovx-implant group. The results suggest a biphasic effect of female gonadal hormone deficiency that may temporarily interfere with the early implant-tissue integration process, and which may be associated with a failure to upregulate a selected set of bone extracellular matrix genes. Once established, however, functional bone-implant integration can be achieved even in ovx rats.

Animals↗
PubMed2002

Digital acoustic analysis of five vowels in maxillectomy patients.

The aim of the study was to characterize the acoustics of vowel articulation in maxillectomy patients. Digital acoustic analysis of five vowels, /a/, /e/, /i/, /o/ and /u/, was performed on 12 male maxillectomy patients and 12 normal male individuals. A simple set of acoustic descriptions called the first and second formant frequencies, F1 and F2, were employed and calculated based on linear predictive coding. The maxillectomy patients had a significantly lower F2 for all five vowels and a significantly higher F1 for only /i/ vowel. From the data plotted on an F1-F2 plane in each subject, we determined the F1 range and the F2 range, which are the differences between the minimum and the maximum frequencies among the five vowels. The maxillectomy patients had a significantly narrower F2 range than the normal controls. In contrast, there was no significant difference in the F1 range. These results suggest that the maxillectomy patients had difficulty in controlling F2 properly. In addition, the speech intelligibility (SI) test was performed to verify the results of this new frequency range method. A high correlation between the F2 range and the score of SI test was demonstrated, suggesting that the F2 range is effective in evaluating the speech ability of maxillectomy patients.

Acoustics↗
PubMed2001

Mastoparan stimulates GABA release from MIN6 cells: relationship between SNARE proteins and mastoparan action.

We examined the action of mastoparan on beta cell exocytosis. Mastoparan stimulated GABA and insulin release from MIN6 beta cells. On the other hand, mastopraran-induced GABA release was decreased by expressing the tetanus toxin C1 light chain in MIN6 cells. We have then investigated the relationship between SNARE proteins and mastoparan action using adenovirus-mediated gene transfer system. Overexpression of t-SNAREs, syntaxin 1A, and SNAP-25 inhibited the mastoparan-induced insulin release by approximately half-fold of control levels, however, the mastoparan-induced GABA release was not affected by these t-SNAREs overexpression. The overexpression of mutant alpha-SNAP (1-285), which inhibits the wild-type alpha-SNAP function in a dominant negative manner, did not influence either mastoparan-induced GABA or insulin release in spite of its marked inhibition of glucose-stimulated insulin release. Our data indicate that mastoparan stimulates GABA exocytosis via vesicular transport; however, SNARE proteins are differently involved in the exocytosis of insulin and GABA.

Animals↗
PubMed2001

Adenovirus-mediated preproinsulin gene transfer into adipose tissues ameliorates hyperglycemia in obese diabetic KKA(y) mice.

We investigated whether adenovirus-mediated preproinsulin gene transfer into insulin target tissues (adipocytes) ameliorates hyperglycemia in diabetic mice. KKA(y) mice, a genetically obese type 2 diabetic animal model, were treated with a single subcutaneous injection of recombinant adenovirus, Adex1CA-human preproinsulin (Adex1CA-pchi), into the epididymal fat pads. pchi mRNA was expressed only in adipose tissue in which mature insulin was produced. Three days after virus injection these mice showed a marked decrease of blood glucose levels (from about 400 to 200 mg/dl), and an intraperitoneal glucose tolerance test revealed the markedly improved glucose tolerance. There was no significant difference in serum insulin levels between control and recombinant adenovirus-treated KKA(y) mice. The normalized glucose levels in diabetic mice were maintained for at least 2 weeks after the virus injection. This strategy could provide a novel and, most importantly, a simple and convenient gene therapy for obese type 2 diabetes patients.

Adenoviridae↗
PubMed2001

Glia-synapse interaction through Ca2+-permeable AMPA receptors in Bergmann glia.

Glial cells express a variety of neurotransmitter receptors. Notably, Bergmann glial cells in the cerebellum have Ca2+-permeable alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptors (AMPARs) assembled without the GluR2 subunit. To elucidate the role of these Ca2+-permeable AMPARs, we converted them into Ca2+-impermeable receptors by adenoviral-mediated delivery of the GluR2 gene. This conversion retracted the glial processes ensheathing synapses on Purkinje cell dendritic spines and retarded the removal of synaptically released glutamate. Furthermore, it caused multiple innervation of Purkinje cells by the climbing fibers. Thus, the glial Ca2+-permeable AMPARs are indispensable for proper structural and functional relations between Bergmann glia and glutamatergic synapses.

Adenoviridae↗
PubMed2001

Acute inhibition of proinsulin biosynthesis at the translational level by palmitic acid.

The effects of fatty acids on pancreatic beta cell are still controversial. Here, in order to determine whether free fatty acids acutely affect beta cell functions, we studied the effect of palmitic acid (PA) on proinsulin biosynthesis and insulin secretion using rat islets in vitro. Exposure of islets to PA for 1 h reduced glucose-stimulated proinsulin biosynthesis in a dose-dependent manner; in contrast, no change in insulin secretion was observed after 1 h incubation with PA. Furthermore, PA treatment did not cause any change of preproinsulin mRNA level during 1-h incubation period. Thus, our data indicate that PA primarily suppresses glucose-induced proinsulin biosynthesis within 1 h at the translational level.

Animals↗