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M Yamaguchi

Publications and source records attributed to M Yamaguchi.

At least 559 records · Page 31Linked to original sources
PubMed1997

Identification of CFDD (common regulatory factor for DNA replication and DREF genes) and role of its binding site in regulation of the proliferating cell nuclear antigen gene promoter.

The Drosophila proliferating cell nuclear antigen (PCNA) gene promoter contains at least three transcriptional regulatory elements, the URE (upstream regulatory element), DRE (DNA replication-related element), and E2F recognition sites. In nuclear extracts of Drosophila Kc cells, we detected a novel protein factor(s), CFDD (common regulatory factor for DNA replication and DREF genes) that appeared to recognize two unique nucleotide sequences (5'-CGATA and 5'-CAATCA) and bind to three sites in the PCNA gene promoter. These sites were located at positions -84 to -77 (site 1), -100 to -93 (site 2) and -134 to -127 (site 3) with respect to the transcription initiation sites. Sites 2 and 3 overlapped with DRE and URE, respectively, and the 5'-CGATA matched with the reported recognition sequence of BEAF-32 (boundary element-associated factor of 32 kDa). Detailed analyses of CFDD recognition sequences and experiments with specific antibodies to DREF (DRE-binding factor) and BEAF-32 suggest that CFDD is different from DREF, UREF (URE-binding factor) and BEAF-32. A UV cross-linking experiment revealed that polypeptides of approximately 76 kDa in the nuclear extract interact directly with the CFDD site 1 sequence. Transient expression assays of chloramphenicol acetyltransferase (CAT) in Kc cells transfected with PCNA promoter-CAT fusion genes carrying mutations in CFDD site 1 and examination of lacZ expression from PCNA promoter-lacZ fusion genes carrying mutations in site 1, introduced into flies by germ line transformation, revealed that CFDD site 1 plays an important role for the promoter activity both in cultured cells and in living flies. In addition to the PCNA gene, multiple CFDD sites were found in promoters of the DNA polymerase alpha and DREF genes, and CFDD binding to the DREF promoter was confirmed. Therefore, CFDD may play important roles in regulation of Drosophila DNA replication-related genes.

Amino Acid Sequence↗
PubMed1997

Expression of functional TrkA receptor tyrosine kinase in the HMC-1 human mast cell line and in human mast cells.

Nerve growth factor (NGF) can influence mast cell development and function in murine rodents by interacting with its receptors on mast cells. We now report the identification of mRNA transcripts of full-length tyrosine kinase-containing trkA, trkB, and trkC neurotrophin receptor genes in HMC-1 human mast cell leukemia cells. Although HMC-1 cells lacked p75 mRNA, they expressed transcripts for the exon-lacking splice variant of trkA (trkAI), truncated trkB (trkB.T1), and truncated trkC. By flow cytometry, HMC-1 cells exhibited expression of TrkA, TrkB, and TrkC receptor proteins containing full-length tyrosine kinase domains. NGF stimulation of HMC-1 cells induced tyrosine phosphorylation of TrkA protein, increased expression of the early response genes c-fos and NGF1-A, and activation of ERK-mitogen-activated protein (MAP) kinase, results which indicate that TrkA receptors in HMC-1 cells are fully functional. Highly purified populations of human lung mast cells expressed mRNAs for trkA, trkB and trkC, whereas preparations of human umbilical cord blood-derived mast cells expressed mRNAs for trkA and trkC, but not trkB. Moreover, preparations of human umbilical cord blood-derived immature mast cells not only expressed mRNA transcript and protein for TrkA, but exhibited significantly higher numbers of chymase-positive cells after the addition of NGF to their culture medium for 3 weeks. In addition, HMC-1 cells expressed mRNAs for NGF, brain-derived neurotrophic factor (BDNF), and neurotrophin-3 (NT-3), the cognate ligands for TrkA, TrkB, and TrkC, whereas NGF and BDNF transcripts were detectable in human umbilical cord blood mast cell preparations. Taken together, our findings show that human mast cells express a functional TrkA receptor tyrosine kinase and indicate that NGF may be able to promote certain aspects of mast cell development and/or maturation in humans. Our studies also raise the possibility that human mast cells may represent a potential source for neurotrophins.

Cell Line↗
PubMed1997

Direct determination of estriol 3- and 16-glucuronides in pregnancy urine by column-switching high-performance liquid chromatography with fluorescence detection.

An HPLC method for the direct and simultaneous determination of estriol 3- and 16-glucuronides in pregnancy urine is described. The method is based on direct derivatization of the glucuronic acid moiety in estriol glucuronides in urine with 6,7-dimethoxy-1-methyl-2(1H)-quinoxalinone-3-propionylcarboxylic acid hydrazide. The derivatization reaction proceeds in aqueous solution (or urine sample) in the presence of pyridine and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide at 37 degrees C. The resulting fluorescent derivatives were separated by column-switching chromatography using a first column (YMC-Pack C4) for clean-up of the derivatives and a second column (YMC Pack Ph) for the complete separation of the derivatives. The derivatives were detected spectrofluorimetrically at 445 nm with excitation at 367 nm. The detection limits (signal-to-noise ratio=3) for estriol 3- and 16-glucuronides were 150 and 180 fmol in a 5 microl of urine (14 and 17 ng ml(-1) urine), respectively. The present method is highly sensitive and simple without any clean-up such as conventional solid-phase extraction.

Chromatography, High Pressure Liquid↗
PubMed1997

TNF-alpha stimulates the biosynthesis of complement C3 and factor B by human umbilical cord vein endothelial cells.

The human umbilical cord vein (HUVEC) endothelial cells synthesize and secrete complement components. We analyzed the regulation of biosynthesis of the third component of complement (C3) and factor B (Bf) by cytokines in endothelial cells. Production of C3 increased after stimulation with TNF-alpha or IL-1beta and that of Bf with TNF-alpha, TNF-beta and IFN-gamma. TNF-alpha was the most effective in stimulating the secretion of C3 and Bf or the expression of mRNA of C3 or Bf. Preincubation with TNF-alpha for at least 36 or 24 h was needed for the stimulation, respectively. TNF-alpha, together with IFN-gamma had synergistic effects and the release of C3 or Bf increased to about 40- and 26-fold higher than those in control cells after incubation with both cytokines.

Cell Line↗
PubMed1997

3,4-Dimethoxybenzylamine as a sensitive pre-column fluorescence derivatization reagent for the determination of serotonin in human platelet-poor plasma.

3,4-Dimethoxybenzylamine is shown to be a highly sensitive pre-column fluorescence derivatization reagent for the determination of serotonin in plasma by high-performance liquid chromatography. The reagent reacts selectively with 5-hydroxyindoles including serotonin in slightly alkaline media in the presence of potassium hexacyanoferrate(III) to give highly fluorescent derivatives. The derivatives of six standard 5-hydroxyindoles (5-hydroxytryptophan, 5-hydroxyindole-3-acetic acid, serotonin, 5-hydroxyindole-3-acetamide, N-acetyl-5-hydroxytryptamine and 5-hydroxytryptophol) are separated within 18 min by isocratic elution using acetonitrile-10 mM phosphate buffer (pH 6.0)-50 mM 1-hexanesulfonic acid on a Wakosil II 5C18RS reversed-phase column. The detection limits (signal-to-noise ratio=3) for the indoles were 1.0-5.7 fmol in a 100-microl injection volume. The method was applied to the measurement of serotonin in human platelet-poor plasma.

Benzylamines↗
PubMed1997

Selective inhibition of vascular cell adhesion molecule-1 expression by verapamil in human vascular endothelial cells.

Up-regulated expression of adhesion molecules on vascular endothelial cells (ECs) is an initial event in leukocyte adhesion to ECs, which is a crucial step in the process of inflammatory or immune reaction leading to organ transplant rejection. Verapamil and other calcium channel blockers have been reported to improve transplantation outcome and seem to possess immunosuppressive functions. Therefore, we tested the effect of verapamil on adhesion molecule expression of ECs and adherence of leukocytes to ECs. Verapamil was added to replicate human umbilical vein EC cultures, before adding cytokines. Protein and mRNA expression of E-selectin, vascular cell adhesion molecule-1 (VCAM-1), and intercellular adhesion molecule-1 were measured by cell-ELISA and by Northern blot analysis after stimulation of ECs. Adherence of leukocytes to ECs was analyzed after stimulation of ECs by tumor necrosis factor-alpha, with pretreatment of verapamil. Verapamil selectively inhibited cytokine-induced protein and mRNA levels of VCAM-1, and suppressed cell adherence between tumor necrosis factor-alpha-stimulated ECs and mononuclear leukocytes or Molt-4 cells. These results suggest that verapamil may suppress immune response partly via inhibition of VCAM-1 expression on ECs and a certain subset of lymphocytes adherent to ECs.

Calcium Channel Blockers↗
PubMed1997

Polyclonal B-cell lymphocytosis with features resembling hairy cell leukemia-Japanese variant.

Polyclonal B lymphocytosis was found in four patients having clinical and hematologic features resembling those of hairy cell leukemia (HCL). All four patients were women between 37 and 67 years of age. Three patients had splenomegaly. Lymphadenopthy was absent or slight. Persistent lymphocytosis was seen in all the patients, and anemia and/or thrombopenia was observed in three of the patients. Abnormal lymphocytes have long microvilli and prominent membranous ruffles on their surfaces. Bone marrow aspirates and biopsy specimens showed increased numbers of abnormal lymphocytes with round nuclei and abundant pale cytoplasm. Although these findings were similar to those of HCL, studies of Ig gene rearrangements and expression showed the polyclonal proliferation of B cells. We called this new disease hairy B-cell lymphoproliferative disorder (HBLD). All four patients exhibited a polyclonal increase in serum IgG. The morphology of the cells in HBLD was more similar to that of leukemia cells of a variant form of HCL (HCL-Japanese variant) than to typical HCL cells. The surface IgG+, CD5-, CD11c+, CD22+, CD24-, CD25- phenotype and the weak tartrate-resistant acid phosphatase activity in the cells were identical to those of HCL cells of the Japanese variant. Our findings suggest that the B cells in HBLD are the nonmalignant counterpart of leukemic B cells in HCL-Japanese variant.

Adult↗
PubMed1997

IgE regulates mouse basophil Fc epsilon RI expression in vivo.

The binding of IgE to high-affinity IgE receptors (Fc epsilon RI) on the surface of mast cells and basophils primes these cells to secrete a panel of proinflammatory mediators upon subsequent exposure to specific Ag. We now find that the level of Fc epsilon RI expression on bone marrow basophils in mice infected with the nematode Strongyloides venezuelensis exhibits a strong positive correlation with the serum concentration of IgE, as was previously reported for human blood basophils. Moreover, the administration of IgE in vivo can significantly upregulate Fc epsilon RI expression on mouse basophils, and genetically IgE-deficient (IgE -/-) mice exhibit a dramatic (approximately 81%) reduction of basophil Fc epsilon RI expression compared with the corresponding normal (IgE +/+) mice. The finding that IgE can be a major regulator of mouse basophil Fc epsilon RI expression in vivo identifies a potentially important mechanism for enhancing the expression of effector cell function in IgE-dependent allergic reactions or immunologic responses to parasites.

Animals↗
PubMed1997

Highly sensitive high-performance liquid chromatographic determination method for a new erythromycin derivative, EM523, and its major metabolites in human plasma and urine using post-column tris(2,2'-bipyridine) ruthenium(III) chemiluminescence detection.

A method for the simultaneous determination of de(N-methyl)-N-ethyl-8,9 -anhydroerythromycin A 6,9-hemiacetal (EM523, I) and its three metabolites in human plasma and urine has been developed using high-performance liquid chromatography (HPLC) with chemiluminescence (CL) detection. Plasma and urine samples spiked with erythromycin as an internal standard were extracted with a mixture of dichloromethane and diethyl ether under alkaline conditions. The organic layer was evaporated under a stream of nitrogen gas. The reconstituted sample was injected into an HPLC apparatus and separated on an ODS column using a gradient elution method. The eluate was reacted on-line with a mixture of tris(2,2'-bipyridine) ruthenium(II) and peroxodisulfate, and the generated CL intensity was detected. Optimization of the CL reaction conditions resulted in a sensitive and stable CL intensity for the determination of I and its metabolites. The recovery of each compound from human plasma and urine, and the sensitivity, linearity, accuracy and precision of the method were satisfactory. The lower limits of quantitation for each compound using 0.2 ml of plasma and 0.1 ml of urine were 1 and 10 ng/ml, respectively. This method has been used for the determination of 1 in samples from clinical trials.

2,2'-Dipyridyl↗
PubMed1997

IgE enhances mouse mast cell Fc(epsilon)RI expression in vitro and in vivo: evidence for a novel amplification mechanism in IgE-dependent reactions.

The binding of immunoglobulin E (IgE) to high affinity IgE receptors (Fc(epsilon)RI) expressed on the surface of mast cells primes these cells to secrete, upon subsequent exposure to specific antigen, a panel of proinflammatory mediators, which includes cytokines that can also have immunoregulatory activities. This IgE- and antigen-specific mast cell activation and mediator production is thought to be critical to the pathogenesis of allergic disorders, such as anaphylaxis and asthma, and also contributes to host defense against parasites. We now report that exposure to IgE results in a striking (up to 32-fold) upregulation of surface expression of Fc(epsilon)RI on mouse mast cells in vitro or in vivo. Moreover, baseline levels of Fc(epsilon)RI expression on peritoneal mast cells from genetically IgE-deficient (IgE -/-) mice are dramatically reduced (by approximately 83%) compared with those on cells from the corresponding normal mice. In vitro studies indicate that the IgE-dependent upregulation of mouse mast cell Fc(epsilon)RI expression has two components: an early cycloheximide-insensitive phase, followed by a later and more sustained component that is highly sensitive to inhibition by cycloheximide. In turn, IgE-dependent upregulation of Fc(epsilon)RI expression significantly enhances the ability of mouse mast cells to release serotonin, interleukin-6 (IL-6), and IL-4 in response to challenge with IgE and specific antigen. The demonstration that IgE-dependent enhancement of mast cell Fc(epsilon)RI expression permits mast cells to respond to antigen challenge with increased production of proinflammatory and immunoregulatory mediators provides new insights into both the pathogenesis of allergic diseases and the regulation of protective host responses to parasites.

Animals↗
PubMed1997

Transcriptional regulation of the Drosophila-raf proto-oncogene by the DNA replication-related element (DRE)/DRE-binding factor (DREF) system.

The DRE/DREF system plays an important role in transcription of DNA replication genes such as those encoding the 180 and 73 kDa subunits of DNA polymerase alpha as well as that for encoding PCNA. In this study, we found two sequences homologous to DRE (5'-TATCGATA-3') in the 5'-flanking region (-370 to -357 with respect to the transcription initiation site) of the D-raf gene and confirmed transcriptional activity through gel mobility shift assays, transient CAT assays, and spatial patterns of lacZ expression in transgenic larval tissues carrying D-raf and lacZ fusion genes. Further, we demonstrated that the D-raf gene is another target of the Zerknüllt (Zen) protein with observation of D-raf repression by Zen protein in cultured cells and its ectopic expression in the dorsal region of the homozygous zen mutant embryo. The evidence of DRE/DREF involvement in regulation of the D-raf gene obtained in this study strongly supports the idea that the DRE/DREF system is responsible for the coordinated regulation of cell proliferation-related genes in Drosophila.

Animals↗
PubMed1997

Hydrogen peroxide-mediated degradation of protein: different oxidation modes of copper- and iron-dependent hydroxyl radicals on the degradation of albumin.

Cupric ions (Cu2+) added to hydrogen peroxide (H2O2) were found to generate hydroxyl radicals (HO) capable of benzoate hydroxylation. Although ferrous (Fe2+) and ferric (Fe3+) ions, when added to H2O2, resulted in very little production of HO, the addition of EDTA to the reaction mixture markedly increased their catalytic activity. In the absence of albumin, catalase (a H2O2 scavenger) and mannitol (an HO radical scavenger) effectively inhibited the formation of HO in H2O2/Cu2+ and H2O2/Fe2+/EDTA oxidation systems. On analysis using SDS-polyacrylamide gel electrophoresis, catalase was shown to prevent the degradation of albumin by both oxidation systems, whereas mannitol was an effective scavenger of the H2O2/Fe2+/EDTA oxidation system but not of the H2O2/Cu2+ oxidation system. Furthermore, the effect of alteration of benzoate hydroxylation and H2O2 consumption on the H2O2/Cu2+ and H2O2/Fe2+/EDTA oxidation systems resulted in opposite behavior that was dependent upon the presence or absence of albumin. These observations suggest that copper ions bind to albumin and induce site-specific degradation by HO generated at the copper-binding site, whereas the Fe2+/EDTA-catalyzed oxidation system induces non-specific degradation of albumin by HO generated by the Fenton reaction between H2O2 and free Fe2+/EDTA in solution.

Albumins↗
PubMed1997

High cyclic transhydrogenase activity catalyzed by expressed and reconstituted nucleotide-binding domains of Rhodospirillum rubrum transhydrogenase.

The hydrophilic, extramembranous domains I (alpha 1 subunit) and III of the Rhodospirillum rubrum nicotinamide nucleotide transhydrogenase were expressed in Escherichia coli and purified therefrom as soluble proteins. These domains bind NAD(H) and NADP(H). respectively, and together they form the enzyme's catalytic site. We have demonstrated recently that the isolated domains I and III of the bovine transhydrogenase (or domain I of R. rubrum plus domain III of the bovine enzyme) reconstitute to catalyze transhydrogenation in the absence of the membrane-intercalated domain II, which carries the enzyme's proton channel. Here we show that the expressed domains I and III of the R. rubrum transhydrogenase catalyze a very high NADP(H)-dependent cyclic transhydrogenation from NADH to AcPyAD (3-acetylpyridine adenine dinucleotide) with a Vmax of 214 mumol AcPyAD reduced (min x mg of domain I)-1. The reaction mechanism is 'ping-pong' with respect to NADH and AcPyAD, as these nucleotides bind interchangeably to domain I, and the stereospecificity of hydride ion transfer is from the 4A position of NADH to the 4A position of AcPyAD. The expressed domain I is dimeric, like the native alpha 1 subunit of the enzyme, but the expressed domain III is monomeric and contains 0.94 mol NADP(H) per mol.

Animals↗
PubMed1997

The mechanism of free radical generation in brain capillary endothelial cells after anoxia and reoxygenation.

We studied the mechanism of reoxygenation injury of cerebral microvessels in cultured rat brain capillary endothelial cells (BCECs). BCECs were isolated from rat cerebral cortices by a two step enzymatic treatment. The monolayers of BCECs were subjected to anoxia for 20 minutes followed by reoxygenation for 3 hours. Cell damage was assessed by measuring the leakage of intracellular lactic dehydrogenase (LDH). The control group was anoxia/reoxygenated BCECs without any protective reagents. To study the protective effect of free radical scavengers and antioxidants, superoxide dismutase, catalase, deferoxamine, oxypurinol, indomethacin, or NG-nitro-L-arginine methyl ester (L-NAME) was applied during anoxia/reoxygenation. Thus 7 experimental conditions were established. Lactic dehydrogenase (LDH) leaked from reoxygenated BCECs due to cell membrane damage. This leakage was almost totally suppressed by superoxide dismutase, indicating that reoxygenation injury of BCECs is mediated by superoxide generation. The other scavengers and antioxidants partially suppressed LDH leakage. Reduction of Ca2+ in the culture medium from 1.6 mM to 0.016 mM also suppressed LDH leakage. These results indicate that BCECs subjected to anoxia/reoxygenation become potent generators of superoxide anion, which is thought to be responsible for reoxygenation injury. The superoxide generation partially depends on the xanthine oxidase and cyclooxygenase pathways. As L-NAME partially suppressed LDH leakage peroxynitrite may contribute to reoxygenation injury of BCECs. The extracellular Ca2+ concentration also plays a critical role in the reoxygenation injury of BCECs.

Animals↗
PubMed1997

The role of calcium ion in anoxia/reoxygenation damage of cultured brain capillary endothelial cells.

Capillary endothelial cells are critical targets in both ischemia and reperfusion of the brain. Arachidonic acids and oxygen free radicals have been shown to cause disruption of blood-brain barrier (BBB) by destruction of capillary endothelial cell membrane. However, the exact mechanism of BBB breakdown by cerebral ischemia/reperfusion remains undetermined. The aim of the present study is to clarify the mechanism of intracellular calcium ion ([Ca2+]i) change in brain capillary endothelial cells under anoxia/reoxygenation. Brains capillary endothelial cells were isolated from ten male Sprague-Dawley rats by a two step enzymatic process. [Ca2+]i was measured by means of a confocal laser scanning microscope using Indo 1-A/M as a calcium indicator. The endothelial cells were subjected to anoxia and reoxygenization under different conditions. [Ca2+]i increased gradually during anoxia and slightly decreased after reoxygenation. Indomethacin and SOD suppressed the elevation of [Ca2+]i during anoxia. NG-nitro-L-arginine methyl ester and catalase moderately suppressed the elevation, however nifedipine did not suppress it at all. In this model, rapid [Ca2+]i change was not observed during the reoxygenation phase. The results indicate that the anoxia induced elevation of [Ca2+]i in the brain capillary endothelial cells depends on superoxide and peroxynitrite generation.

Animals↗