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Satoshi Tanaka

Publications and source records attributed to Satoshi Tanaka.

At least 127 records · Page 7Linked to original sources
PubMed2002

Circular dichroism spectra of DNA quadruplexes [d(G(5)T(5))](4) as formed with G(4) and T(4) tetrads and [d(G(5)T(5)). d(A(5)C(5))]2 as formed with Watson-Crick-like (G-C)(2) and (T-A)(2) tetrads.

We utilize electrophoresis and find that a thermally treated equimolar mixture of the oligonucleotide d(G(5)T(5)) and its complementary oligonucleotide d(A(5)C(5)) exhibits either two bands or a single band in one lane, depending on the conditions of the incubation solutions. The thermally treated d(G(5)T(5)) solution loaded in a different lane exhibits a single band of the parallel quadruplex [d(G(5)T(5))](4), which is composed of homocyclic hydrogen-bonded G(4) and T(4) tetrads previously proposed. For the thermally treated equimolar mixture of d(G(5)T(5)) and d(A(5)C(5)), the fast band is assigned to a Watson-Crick d(G(5)T(5)). d(A(5)C(5)) duplex, so that the slow band with the same low mobility as that of [d(G(5)T(5))](4) may be assigned to either [d(G(5)T(5))](4) itself or a [d(G(5)T(5)). d(A(5)C(5))](2) quadruplex. If the latter compound is true, this may be the antiparallel quadruplex composed of the heterocyclic hydrogen-bonded G-C-G-C and T-A-T-A tetrads proposed previously. After removing these three bands for the duplex and two kinds of hypothetical quadruplexes, we electrophoretically elute the corresponding compounds in the same electrophoresis buffer using an electroeluter. The eluted compounds are ascertained to be stable by electrophoresis. The circular dichroism (CD) and UV absorption spectra measured for the three isolated compounds are found to be clearly different. For the electrophoretic elution of the hypothetical [d(G(5)T(5))](4) quadruplex, the result of the molecularity of n = 4 obtained from the CD melting curve analysis provides further support for the formation of the parallel [d(G(5)T(5))](4) quadruplex already proposed. For the thermally treated equimolar mixture of d(G(5)T(5)) and d(C(5)A(5)), the fast band with a molecularity of n = 2 corresponds to the Watson-Crick duplex, d(G(5)T(5)). d(A(5)C(5)). The slow band with a molecularity of n = 4 indicates the antiparallel quadruplex [d(G(5)T(5)). d(A(5)C(5))](2), whose observed CD and UV spectra are different from those of [d(G(5)T(5))](4). By electrophoresis, after reannealing the eluted compound [d(G(5)T(5)). d(A(5)C(5))](2), a distinct photograph showing the band splitting of this quadruplex band into the lower duplex and upper quadruplex bands is not possible; but by a transilluminator, we occasionally observe this band splitting with the naked eye. The linear response polarizability tensor calculations for the thus determined structures of the [d(G(5)T(5))](4) quadruplex, the McGavin-like [d(G(5)T(5)). d(A(5)C(5))](2) quadruplex, and the Watson-Crick d(G(5)T(5)). d(A(5)C(5)) duplex are found to qualitatively predict the observed CD and UV spectra.

Base Sequence↗
PubMed2002

Histamine H(2) receptor-mediated modulation of local cytokine expression in a mouse experimental tumor model.

Accumulating evidence indicates that histamine is involved in the modulation of cytokine expression patterns. We previously reported that daily treatment with the H(2) receptor antagonist, cimetidine, suppressed tumor growth through alteration of the local cytokine expression pattern. In this study, we used a mouse strain genetically lacking histidine decarboxylase (HDC), to evaluate the role of endogenous histamine synthesis on cytokine expression and tumor development. In the mutant mice, cimetidine had no effect on tumor growth, whereas an H(2) agonist, dimaprit, significantly enhanced tumor growth. When the HDC-deficient mice were implanted with mutant CT-26 cells stably expressing HDC, drastic suppression of tumor growth by cimetidine was observed, which was accompanied by augmentation of mRNA expression of LT-beta, TNF-alpha, and IFN-gamma in the tumor tissues. These results suggest that endogenous histamine synthesis in tumor tissues suppresses local tumor immunity via the H(2) receptors, resulting in tumor growth promotion.

Animals↗
PubMed2002

Preparation of polymer-supported benzyllithium reagents.

Cross-linked polystyrenes (2, 8, and 11) possessing pendant double bonds conjugated with benzene ring were prepared by both polymerization method and chemical modification of pre-formed polymers. These double bonds were readily lithiated with n-butyllithium to give the benzyllithium species on the polymer. The polymer supported benzylic anions (3 and 12) are a versatile polymeric organometallic reagent that reacted with various kinds of electrophiles.

Anions↗
PubMed2002

Antigen-independent induction of histamine synthesis by immunoglobulin E in mouse bone marrow-derived mast cells.

Immunoglobulin (Ig)E-mediated activation of mast cells has long been thought to occur only when Fc(epsilon)RI receptor-bound IgE is cross-linked via multivalent antigens. However, recent studies have raised the possibility that mast cells may be activated by the binding of IgE to the Fc(epsilon)RI receptor in the absence of antigen. Here we demonstrate that IgE binding without antigen induces the expression of histidine decarboxylase (HDC) in mouse interleukin (IL)-3-dependent bone marrow-derived mast cells (BMMCs). The induction of HDC by the binding of IgE was found to require an influx of extracellular calcium ions, which was attenuated by pretreatment with U73122, a phospholipase C inhibitor. Furthermore, the increase in HDC activity upon sensitization with IgE was completely suppressed by pretreatment of BMMCs with protein kinase C inhibitors, such as H7, staurosporine, and Gö6976. In addition, immediate activation of the tyrosine kinase Lyn was not detectable upon treatment with IgE. These results suggest that the binding of IgE to its receptor in the absence of antigen results in de novo synthesis of HDC in BMMCs through a signaling pathway distinct to that operating during antigen-stimulated Fc(epsilon)RI activation.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed2002

Coherent x-ray Raman spectroscopy: a nonlinear local probe for electronic excitations.

Nonlinear x-ray four-wave mixing experiments are becoming feasible due to rapid advances in high harmonic generation and synchrotron radiation coherent x-ray sources. By tuning the difference of two x-ray frequencies across the valence excitations, it is possible to probe the entire manifold of molecular electronic excitations. We show that the wave vector and frequency profiles of this x-ray analogue of coherent Raman spectroscopy provide an excellent real-space probe that carries most valuable structural and dynamical information, not available from spontaneous Raman techniques.

Journal Article↗
PubMed2002

Manipulation of bacterial adhesion and proliferation by surface charges of electrically polarized hydroxyapatite.

The manipulation of bacterial adhesion and proliferation by surface charges built onto the surfaces of electrically polarized bioceramic hydroxyapatite (HAp) was investigated. The gram-positive bacteria Staphylococcus aureus (S. aureus) and the gram-negative bacteria Escherichia coli (E. coli) were cultivated on negatively charged, positively charged, and non-charged HAp surfaces (denoted as N-, P-, and 0-surface, respectively). The electrostatic force caused by the surface charges experimentally was proven to affect both adhesion and proliferation. Compared with the 0-surface of HAp ceramics over a 3-h cultivation, the population of adhered bacteria rapidly multiplied on the N-surface whereas it multiplied quite slowly on the P-surface. Compared with the 0-surface over a cultivation period of 12 to 72 h, the proliferation rate of the bacterial cell density per colony was accelerated on the N-surface and decelerated on the P-surface. The above results are attributed (1) to the electrostatic interaction between the cell surfaces and the charged surfaces of the polarized HAp, (2) to the stimulus of the electrostatic force for bacterial cells, and (3) to the concentration of the nutrient for the bacteria.

Bacterial Adhesion↗
PubMed2002

Expression of L-histidine decarboxylase in mouse male germ cells.

Histamine synthesis in male reproductive tissues remains largely unknown. The interaction between stem cell factor and its receptor, c-Kit, has been found to be essential for the maturation of male germ cells and peripheral mast cells. Based on this analogy, we investigated the expression of histidine decarboxylase (HDC), the rate-limiting enzyme of histamine synthesis, in mouse male germ cells. Immunohistochemical analyses revealed that HDC is localized in the acrosomes of spermatids and spermatozoa. In the testis, epididymis, and spermatozoa, a significant amount of histamine and HDC activity were detected. W/W(V) mice, known to lack most of their germ cells in the seminiferous tubules, were found to lack HDC protein expression as well as HDC activity in the testis. An in vitro acrosome reaction induced by a calcium ionophore, caused the release of histamine from epididymal spermatozoa. Our observations indicate that histamine is produced in and released from the acrosomes.

Acrosome Reaction↗
PubMed2002

Differentiation of trophoblast lineage is associated with DNA methylation and demethylation.

Our previous study has shown that the placenta and kidney had different genomic methylation patterns regarding CpG island loci detected by restriction landmark genomic scanning (RLGS). To investigate whether differentiation involves changes in DNA methylation, we analyzed the rat Rcho-1 cell line, which retains trophoblast cell features and differentiates from stem cells into trophoblast giant cells in vitro. By RLGS, a total of 1,232 spots were identified in the Rcho-1 stem and differentiated giant cells. Four spots (0.3%) were detected only in giant cells, implying that the loci were originally methylated, but became demethylated during differentiation. Another four spots (0.3%) were detected only in stem cells, implying that these loci, originally unmethylated, became methylated during differentiation. DNAs from three loci that became methylated during differentiation were cloned and sequenced. All showed high homologies with expressed sequence tags (ESTs) or with genomic DNA of other species, suggesting that these loci are biologically important. Thus, the eight differentially methylated loci should be good tools to study epigenetic modification specific to differentiation of trophoblast giant cells.

Animals↗
PubMed2002

Plasma extravasation induced by dietary supplemented histamine in histamine-free mice.

Histidine decarboxylase (HDC) synthesizes endogenous histamine from histidine in mammals. To evaluate the role of histamine in skin allergic reaction, we used HDC gene knockout mice lacking histamine. No plasma extravasation reaction was observed in HDC-/- mice after passive cutaneous anaphylaxis (PCA) test. Compound 48/80, a mast cell granule depletor, produced plasma extravasation inHDC+/+ mice but no extravasation in HDC-/- mice. Interestingly, orally administered histamine was distributed in the skin in HDC-/- mice and in these histamine-supplemented mice the plasma extravasation reaction was observed after the injection of compound 48/80 and the PCA test. Cultured bone marrow-derived mast cells of HDC-/- mice took up histamine from the histamine-supplemented medium into the secretory granules. The absorbed histamine was released in response to the same antigen and antibody combination used as in PCA test. In contrast to the immediate-type response, the delayed-type hypersensitive response, observed as a thickening of the ear skin after trinitrochlorobenzene challenge (following sensitization), showed no differences between HDC+/+ and HDC-/- mice. Therefore, among the allergic skin reactions, histamine is revealed to be an important mediator especially for the plasma extravasation in an immediate-type allergy model.

Animals↗
PubMed2002

A novel, brain-specific mouse drebrin: cDNA cloning, chromosomal mapping, genomic structure, expression, and functional characterization.

Drebrin A, a major neuronal actin-binding protein, regulates the dendritic spine shapes of neurons. Here, we have cloned and characterized a novel mouse cDNA clone encoding a truncated form of drebrin A, named s-drebrin A. Analysis of the genomic organization of the mouse drebrin gene (Dbn1), which mapped to the central portion of chromosome 13, revealed that isoforms including s-drebrin A are generated by alternative splicing from a single drebrin gene. The s-drebrin A mRNA was expressed in the brain, but not in non-neuronal tissues. The s-drebrin A expression was barely detected in the embryonic brain, but was upregulated during postnatal development of the brain. Overexpression of GFP-tagged s-drebrin A in fibroblasts showed it to be associated with actin filaments and with changes in actin cytoskeleton organization. These findings suggest that s-drebrin A has a role in spine morphogenesis, possibly by competing the actin-binding activity with drebrin A.

Actins↗
PubMed2002

Changes in phosphodiesterase activity in the developing rat submandibular gland.

Developmental changes (from 2 to 26 weeks) in phosphodiesterase (PDE) activity in the rat submandibular gland were investigated. Major activities for both cAMP- and cGMP-PDE were present in the 100000 x g supernatant fractions (70-90% of total activities), but not in the pellet fractions, during development. The effects of stimulators (Ca(2+)/calmodulin and cGMP) and inhibitors (cGMP, cilostamide, rolipram and zaprinast) were investigated in the supernatant fractions. During development, PDE4 (cAMP-specific PDE) was a major PDE, indicating that the majority of cAMP is hydrolysed by PDE4. In the young rat, PDE1 hydrolysed cGMP three-fold more than the control, and PDE2 (cGMP-stimulated PDE) was present, indicating that the concentration of intracellular cGMP may be enhanced, and cGMP may function in the growth pathway in the submandibular gland. Chromatograms eluted on a Mono Q HR5/5 ion-exchange column supported the results of the inhibition studies: PDE1, PDE2, PDE3, PDE4 and PDE5 were present in the young submandibular gland, and PDE1, PDE3, PDE4 and PDE5 in the adult gland. Expression of PDE5 was detected by inhibition studies, reverse transcriptase-polymerase chain reaction and Western blotting in the submandibular gland.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed2002

Epigenetic marks by DNA methylation specific to stem, germ and somatic cells in mice.

BACKGROUND: DNA methylation is involved in many gene functions such as gene-silencing, X-inactivation, imprinting and stability of the gene. We recently found that some CpG islands had a tissue-dependent and differentially methylated region (T-DMR) in normal tissues, raising the possibility that there may be more CpG islands capable of differential methylation. RESULTS: We investigated the genome-wide DNA methylation pattern of CpG islands by restriction landmark genomic scanning (RLGS) in mouse stem cells (ES, EG and trophoblast stem) before and after differentiation, and sperm as well as somatic tissues. A total of 247 spots out of 1500 (16%) showed differences in the appearance of their RLGS profiles, indicating that CpG islands having T-DMR were numerous and widespread. The methylation pattern was specific, and varied in a precise manner according to cell lineage, tissue type and during cell differentiation. CONCLUSIONS: Genomic loci with altered methylation status seem to be more common than has hitherto been realized. The formation of DNA methylation patterns at CpG islands is one of the epigenetic events which underlies the production of various cell types in the body. These findings should have implications for the use of embryonic stem cells and cells derived from them therapeutically, and also for the cloning of animals by the transfer of somatic cell nuclei.

Animals↗
PubMed2002

A novel animal model of thymic tumour: development of epithelial thymoma in transgenic rats carrying human T lymphocyte virus type I pX gene.

The pX region encodes a major product of human T lymphocyte virus type I (HTLV-I) that has been implicated previously in tumour formation. To investigate the pathogenesis of pX gene in lymphoid tissues, we established a series of novel transgenic rats carrying the pX gene under the control of a rat lymphocyte-specific protein tyrosine kinase (p56lck) proximal promoter. The transgene was constructed with the -269 to +26 region of a rat p56lck proximal promoter and the pX cDNA, and was microinjected into fertilized ova of Fischer 344/jcl female rats. Six transgenic lines from 114 pups were established. Integration and expression of the transgene were detected by polymerase chain reaction (PCR) and Southern hybridization or by reverse transcriptase-PCR, northern hybridization, and immunostaining. Thymic tumours with lethal expansion occurred in 4 of 6 transgenic lines. The tumour consisted of spindle shaped cells. Immunohistochemical and ultra-structural analysis characterized the tumour cells to as epithelial cell type, and in the tumour arose in the medulla. Therefore, the tumour is classified into predominantly epithelial and spindle cell of medullary thymoma (type A of the new World Health Organization classification), as based on the human classification. Tumor occurrence increased in proportion to levels of the pX transcription in the thymus, for each line, and sex distinction was evident regarding rates related to tumour expansion. The transgenic rat model described here is suitable as a model for analysing tumorigenesis in epithelial thymoma occurring in humans.

Animals↗
PubMed2002

Gastric acid secretion in L-histidine decarboxylase-deficient mice.

BACKGROUND & AIMS: Histamine, gastrin, and acetylcholine are known to be the primary secretagogues of gastric acid secretion, but how the roles are shared among these secretagogues remains to be fully clarified. To evaluate the cooperation between histamine and the other secretagogues, acid secretion responses induced by each secretagogue were measured in L-histidine decarboxylase (HDC)-deficient mice. METHODS: Acid secretion was measured by the titration of acid under anesthesia. The expression of selected genes involved in acid secretion was determined by Northern blot and/or immunoblot analysis. Histamine-2 (H(2)) receptor binding in the gastric mucosa was investigated using [(3)H]tiotidine. RESULTS: HDC-deficient mice showed low basal and high exogenous histamine-stimulated acid secretion. The mutant mice showed hypergastrinemia and did not undergo acid secretion upon treatment with exogenous gastrin. However, carbachol stimulated weak and transient acid secretion in the mutants. The Bmax values for H(2) and the expression of Gs alpha in gastric mucosal membranes were higher in the mutants than in the wild-type mice. CONCLUSIONS: This study confirms the concept that histamine production is essential for gastric acid secretion induced by gastrin, but not for that induced by carbachol. HDC-deficient mice should be a suitable model for further functional analyses of the correlation between histamine and the other acid secretagogues.

Animals↗
PubMed2002

New characterization method for pore and packing structure in powder compacts using confocal laser scanning microscope.

The internal structure of powder assemble was observed by a confocal laser scanning microscope and the results were compared with those of other conventional methods. Two kinds of specimens were examined in this paper: powder compacts from alumina granules and set plaster of gypsum. The structure was sensitive to humidity during pressing of the granule compact of alumina containing polyvinyl alcohol as a binder. Narrow interstices were noted along the boundaries of granules in low humidity. However, uniform internal structure was noted in high humidity. The origin of the difference of packing structure was attributed to the change of binder characteristics with humidity. Interstices were formed in low humidity due to poor adhesion of binder and spring back after pressure removal. The superior capability of the present characterization technique can distinguish a minor difference of internal structure successfully.

Journal Article↗
PubMed2002

CO(2) response element and corresponding trans-acting factor of the promoter for ribulose-1,5-bisphosphate carboxylase/oxygenase genes in Synechococcus sp. PCC7002 found by an improved electrophoretic mobility shift assay.

We analyzed the promoter of the genes encoding the ribulose-1,5-bisphosphate carboxylase/oxygenase (rbc) in the cyanobacterium Synechococcus sp. PCC7002 and localized the CO(2)-regulatory element. Cyanobacterial transformants were constructed with several DNA segments of the rbc promoter fused to the chloramphenicol acetyltransferase (CAT) gene, and their acetyltransferase activities were analyzed under 0.03% and 1% CO(2) conditions. We found that the AT-rich element localized from -262 to -291 relative to the rbc translation-starting site was required for CO(2)-dependent repression. Fluorescent-labeled oligonucleotide probes of identical sequence to the AT-rich element were reacted with protein extracts from cells cultured under conditions of low and high CO(2) atmospheric content. We detected a gel retardation complex of a strong signal intensity in extracts from cells cultured under 15% CO(2), but only a weak signal from cells cultured under 1% CO(2). Moreover, a DNA affinity precipitation assay identified a 16-kDa protein that bound to nucleotide sequences within the AT-rich element. The partial amino acid sequence of the protein was similar to the deduced protein sequences of ORF129 and ORF155 from Synechocystis 6803. Our findings suggest that the AT-rich element plays a role as a negative CO(2)-regulatory element and its trans-acting factor possibly regulates the rbc transcription in response to CO(2) levels.

Adenosine Triphosphatases↗
PubMed2002

[A case of infected subdural hematoma following chronic subdural hematoma irrigation].

A 71-year-old female complicating Parkinson disease and diabetes mellitus was admitted to our medical center for urinary tract infection one month after burr hole irrigation and drainage of left chronic subdural hematoma. Klebsiella pneumonia was detected in the bacterial culture of her urine. As antibiotic therapy started, her condition and peripheral white blood cell counts were improved. But consciousness level got worsened and right hemiparesis appeared. A CT scan showed re-accumulation of left subdural fluid so an emergent irrigation was performed. The old hematoma with slightly yellowish, bloody purulent fluid was found and an intracapsular drain was inserted. Klebsiella pneumonia was detected from the bacterial culture of the hematoma. After 10 days, a CT scan showed subdural fluid collection again, so, total hematoma capsule removal was performed. After the operation, her neurological and serological condition improved and she was discharged without any neurological deficits. Klebsiella pneumonia existing urinary tracts rarely infected subdural hematoma cavity via hematogenous dissemination. We must keep in mind this complication may occur when we see compromised host like this case. Total removal of infected hematoma capsule is considered as radical treatment.

Aged↗