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S Ishida

Publications and source records attributed to S Ishida.

At least 19 recordsLinked to original sources
PubMed2006

Identification of novel E2F1 target genes regulated in cell cycle-dependent and independent manners.

The transcription factor E2F mediates cell cycle-dependent expression of genes important for cell proliferation in response to growth stimulation. To further understand the role of E2F, we utilized a sensitive subtraction method to explore new E2F1 targets, which are expressed at low levels and might have been unrecognized in previous studies. We identified 33 new E2F1-inducible genes, including checkpoint genes Claspin and Rad51ap1, and four genes with unknown function required for cell cycle progression. Moreover, we found three groups of E2F1-inducible genes that were not induced by growth stimulation. At least, two groups of genes were directly induced by E2F1, indicating that E2F1 can regulate expression of genes not induced during the cell cycle. One included Neogenin, WASF1 and SGEF genes, which may have a role in differentiation or development. The other was the cyclin-dependent kinase inhibitor p27(Kip1), which was involved in suppression of inappropriate cell cycle progression induced by deregulated E2F. E2F1-responsive regions of these genes were located more upstream than those of typical E2F targets and did not have typical E2F sites. These results indicate that there are groups of E2F1 targets, which are regulated in a distinct manner from that of typical E2F targets.

Animals↗
PubMed2006

Progression rate of ALSFRS-R at time of diagnosis predicts survival time in ALS.

The authors calculated the progression rate (DeltaFS) using the total revised ALS Functional Rating Scale (ALSFRS-R) and symptom duration at diagnosis in 82 Japanese patients with ALS. Survival (death or tracheostomy) differed significantly with the DeltaFS and postdiagnostic period according to log-rank testing, but Cox proportional hazards modeling revealed no strong association between total ALSFRS-R and mortality, suggesting that the DeltaFS provides an additional predictive index beyond ALSFRS-R alone.

Aged↗
PubMed2005

Flow-cytometric analysis on cytotoxic effect of thimerosal, a preservative in vaccines, on lymphocytes dissociated from rat thymic glands.

There is a concern on the part of public health community that adverse health consequence by thimerosal, a preservative in vaccines for infants, may occur among infants during immunization schedule. Therefore, the cytotoxic action of thimerosal was examined on lymphocytes dissociated from thymic glands of young rats using a flow cytometer and respective fluorescent probes for monitoring changes in intracellular Ca2+ concentration ([Ca2+]i) and membrane potential, and for discriminating intact living cells, apoptotic living cells and dead cells. Incubation with thimerosal at 3 microM or more (up to 30 microM) for 60 min depolarized the membranes, associated with increasing the [Ca2+]i. Thimerosal at 30 microM induced an apoptotic change in membranes of almost all living cells. Furthermore, the prolonged incubation with 30 microM thimerosal induced a loss of membrane integrity, leading to cell death. Since the blood concentration of thimerosal after receiving vaccines is theoretically submicromolar, it may be unlikely that thimerosal affects lymphocytes of infants.

Animals↗
PubMed2003

Radical anion of isolable dialkylsilylene.

By the reduction of an isolable dialkylsilylene, 2,2,5,5-[tetrakis(trimethylsilyl)]-1-silacyclopentane-1,1-diyl (1), with cesium, rubidium, potassium, sodium, and lithium 4,4'-di(tert-butyl)biphenylide in DME at low temperatures, the corresponding silylene radical anion 2 was generated as the first persistent silylene radical anion in solution and characterized by ESR spectroscopy. Radical anion 2 is rather stable at -70 degrees C in DME but decomposes rapidly at room temperature with a half-life time of ca. 20 min. The g-factor and 29Si hyperfine splitting constants (hfs's) of 2 are almost independent of the countercations, indicating that 2 exists as a free ion or a solvent-separated ion pair in a polar DME solution. A very small hfs due to the 29Si nucleus of the divalent silicon (3.0 mT) as well as a very large g-factor (2.0077) indicates that an unpaired electron is accommodated in the vacant 3ppi orbital of silylene 1.

Journal Article↗
PubMed2003

A stable silicon-based allene analogue with a formally sp-hybridized silicon atom.

Carbon chemistry exhibits a rich variety in bonding patterns, with homo- or heteronuclear multiple bonds involving sp-hybridized carbon atoms as found in molecules such as acetylenes, nitriles, allenes and carbon dioxide. Carbon's heavier homologues in group 14 of the periodic table--including silicon, germanium and tin--were long thought incapable of forming multiple bonds because of the less effective p(pi)-p(pi) orbital overlap involved in the multiple bonds. However, bulky substituents can protect unsaturated bonds and stabilize compounds with formally sp-hybridized heavy group-14 atoms: stable germanium, tin and lead analogues of acetylene derivatives and a marginally stable tristannaallene have now been reported. However, no stable silicon compounds with formal sp-silicon atoms have been isolated. Evidence for the existence of a persistent disilaacetylene and trapping of transient 2-silaallenes and other X = Si = X' type compounds (X, X' = O, CR2, NR, and so on) are also known, but stable silicon compounds with formally sp-hybridized silicon atoms have not yet been isolated. Here we report the synthesis of a thermally stable, crystalline trisilaallene derivative containing a formally sp-hybridized silicon atom. We find that, in contrast to linear carbon allenes, the trisilaallene is significantly bent. The central silicon in the molecule is dynamically disordered, which we ascribe to ready rotation of the central silicon atom around the molecular axis.

Journal Article↗
PubMed2003

Serum inhibitors for human mast cell growth: possible role of retinol.

BACKGROUND: In vitro culture systems have been used to study the physiological and pathological characteristics of human mast cells. However, there are some differences in proliferation and maturation of mast cells between fetal bovine serum (FBS)-containing and serum-deprived cultures. Accordingly, we attempted to identify circulating factor(s) affecting the development of human mast cells. METHODS: We measured the serum levels of retinol and several cytokines. To elucidate the antiproliferative effects of the serum, a retinoic acid receptor (RARalpha) antagonist and neutralizing antibodies against cytokines were used. RESULTS: Similar to FBS, human serum dose-dependently suppressed the growth of tryptase+ cells from CD34+ cord blood cells or 20-week cultured mast cells under stimulation with stem cell factor (SCF). The serum-mediated inhibition might be based on a decline in proliferation rate. Among inhibitors for mast cell growth, retinol and transforming growth factor (TGF)-beta1 were present at high levels in human serum. In contrast with anti-TGF-beta1 antibody, an RARalpha antagonist counteracted the serum-induced suppression of human mast cell proliferation. CONCLUSIONS: Our results suggest that retinol and its derivatives act as a circulating regulator for human mast cell growth. The RARalpha antagonist may be a useful tool to obtain higher numbers of mast cells in FBS-containing cultures.

Animals↗
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↗
PubMed2001

Predicting the clinical status of human breast cancer by using gene expression profiles.

Prognostic and predictive factors are indispensable tools in the treatment of patients with neoplastic disease. For the most part, such factors rely on a few specific cell surface, histological, or gross pathologic features. Gene expression assays have the potential to supplement what were previously a few distinct features with many thousands of features. We have developed Bayesian regression models that provide predictive capability based on gene expression data derived from DNA microarray analysis of a series of primary breast cancer samples. These patterns have the capacity to discriminate breast tumors on the basis of estrogen receptor status and also on the categorized lymph node status. Importantly, we assess the utility and validity of such models in predicting the status of tumors in crossvalidation determinations. The practical value of such approaches relies on the ability not only to assess relative probabilities of clinical outcomes for future samples but also to provide an honest assessment of the uncertainties associated with such predictive classifications on the basis of the selection of gene subsets for each validation analysis. This latter point is of critical importance in the ability to apply these methodologies to clinical assessment of tumor phenotype.

Bacillus anthracis↗
PubMed2001

SOX6 binds CtBP2 to repress transcription from the Fgf-3 promoter.

Fgf-3 is expressed in a complex pattern during mouse development. Previously, an essential regulatory element PS4A was identified in the promoter region, and shown to bind at least three factors. To identify the transcription factor(s), we used a yeast one-hybrid screen and obtained a novel Sox6 cDNA (SOX6D). When introduced into cells it strongly repressed activity from both an Fgf-3 reporter gene as well as an artificial promoter containing three PS4A elements. In situ hybridisation analysis showed that Sox6 and Fgf-3 are co-expressed in the otic vesicle of E9.5 mouse embryos in a mutually exclusive pattern, consistent with a repression of Fgf-3 transcription by SOX6. To characterise additional factor(s) involved in Fgf-3 gene repression, a yeast two-hybrid screen was used with the N-terminal portion of SOX6D. Mouse CtBP2 cDNA clones were isolated and shown to bind SOX6 in yeast and mammalian cells. Furthermore, mutational analysis of SOX6 showed that binding to CtBP2, and its responsiveness to this co-repressor, were dependent on a short amino acid sequence motif PLNLSS. Co-expression studies in NIH3T3 cells showed that SOX6 and CtBP2 co-operate to repress activity from the Fgf-3 promoter through the enhancer element PS4A. These results show that SOX6 can recruit CtBP2 to repress transcription from the Fgf-3 promoter.

Alcohol Oxidoreductases↗
PubMed2001

Decreased bone mass and increased bone turnover with valproate therapy in adults with epilepsy.

BACKGROUND: Bone loss and hypovitaminosis D are reported in patients taking antiepileptic drugs, but little is known about changes in bone and calcium metabolism from valproic acid (VPA). OBJECTIVE: To assess the relationship of VPA to bone mass and calcium metabolism in 40 adults with epilepsy on long-term VPA monotherapy, 40 age- and sex-matched epileptic patients taking phenytoin (PHT), and 40 healthy control subjects. Bone mineral density (BMD) of the second metacarpal was determined as T- and Z-scores. RESULTS: BMD reduction from control values was 14% (12% in men, 16% in women) with VPA and 13% (12% in men, 15% in women) with PHT. Among patients on VPA, nine (23%) had T-scores below -2.5 SD, suggesting osteoporosis; 15 (37%) had T-scores between -1 and -2.5 SD, suggesting osteopenia. Serum concentrations of calcium were significantly higher with VPA than in PHT or control groups. Serum concentrations of bone Gla protein (a bone formation marker) and pyridinoline cross-linked carboxy-terminal telopeptide of type I collagen (ICTP; a bone resorption marker) associated with either drug significantly exceeded control values. Z-scores for BMD in the VPA group correlated negatively with calcium and ICTP. High ICTP correlated positively with ionized calcium, implying that increased bone resorption caused the latter. CONCLUSION: Long-term VPA monotherapy can increase bone resorption, leading to decreased BMD.

Adult↗
PubMed2001

An increase in circulating mast cell colony-forming cells in asthma.

We compared a potential to generate mast cells among various sources of CD34(+) peripheral blood (PB) cells in the presence of stem cell factor (SCF) with or without thrombopoietin (TPO), using a serum-deprived liquid culture system. From the time course of relative numbers of tryptase-positive and chymase-positive cells in the cultured cells grown by CD34(+) PB cells of nonasthmatic healthy individuals treated with G-CSF, TPO appears to potentiate the SCF-dependent growth of mast cells without influencing the differentiation into mast cell lineage. CD34(+) PB cells from asthmatic patients in a stable condition generated significantly more mast cells under stimulation with SCF alone or SCF+TPO at 6 wk of culture than did steady-state CD34(+) PB cells of normal controls. Single-cell culture studies showed a substantial difference in the number of SCF-responsive or SCF+TPO-responsive mast cell progenitors in CD34(+) PB cells between the two groups. In the presence of TPO, CD34(+) PB cells from asthmatic children could respond to a suboptimal concentration of SCF to a greater extent, compared with the values obtained by those of normal controls. Six-week cultured mast cells of asthmatic subjects had maturation properties (intracellular histamine content and tryptase/chymase enzymatic activities) similar to those derived from mobilized CD34(+) PB cells of nonasthmatic subjects. An increase in a potential of circulating hemopoietic progenitors to differentiate into mast cell lineage may contribute to the recruitment of mast cells toward sites of asthmatic mucosal inflammation.

Adolescent↗