Biomedical subjects

Y Tanaka

Publications and source records attributed to Y Tanaka.

At least 181 records · Page 10Linked to original sources

PubMed2001

Novel betacellulin derivatives. Separation of the differentiation activity from the mitogenic activity.

Betacellulin (BTC) is a member of the epidermal growth factor family. It has two biological activities: mitogenic activity in fibroblasts and vascular smooth muscle cells, and differentiation activity for the differentiation of pancreatic acinar AR42J cells into insulin-secreting cells. The previous finding that recombinant BTC promotes the neogenesis of beta-cells in a mouse model supports the possibility that BTC is a therapeutic protein. However, the mitogenic activity of BTC may not be needed for differentiation into beta-cells and may cause a side effect in clinical use. We prepared several derivatives of BTC to segregate the two activities, to decrease the mitogenic activity, and to maintain the differentiation activity. We succeeded in obtaining BTC derivatives segregated by the two biological activities by preparing truncated-type derivatives. A derivative of BTC, BTC24-76, with a truncated N-terminal 23 amino acids and C-terminal 4 amino acids, was 2.5-fold more active in differentiation and had one-tenth of the mitogenic activity. The derivatives described in the present study should be helpful in future applications as therapeutic proteins and in basic research for discovery of a BTC-specific receptor.

Amino Acid Sequence↗

PubMed2001

Photothermal temperature control of a chemical reaction on a microchip using an infrared diode laser.

We have demonstrated that a miniaturized device with IR laser heating of the solvent, based on a photothermal effect, is capable of fast and localized control of an enzymatic reaction on a microchip under flow conditions. Using noncontact spectroscopic temperature-sensing techniques, we measured temperature dynamics and spatial distribution and compared the measurements with results of numerical simulation analysis. The device was operated at ultrafast heating and cooling rates of 67 and 53 degrees C/s, respectively, which is 30 times faster than conventional systems and 3-6 times faster than electrothermal miniaturized thermocyclers. The IR laser-mediated heater is characterized by a significantly reduced heated volume of only 5 nL, compared to existing chip-based systems with electrothermal heating. Direct heating of a sample with extremely small heat capacity led us to a fast heating rate, and efficient heat removal through heat transfer to the glass substrate resulted in a fast cooling rate. Reproducible temperature levels with dwell times shorter than 0.5 s were achieved. The enzyme reaction on a chip was successfully controlled with 0.6-s time resolution, using periodic photothermal heating by IR laser. The IR diode laser is compact and thus suits well the miniaturized system design. Our work gives the basis for integration in a chip format of a variety of chemical processes that require fast temperature control.

Journal Article↗

PubMed2001

A critical role for mouse CXC chemokine(s) in pulmonary neutrophilia during Th type 1-dependent airway inflammation.

Ag-specific Th1 and Th2 cells have been demonstrated to play a critical role in the induction of allergic diseases. Here we have investigated the precise mechanisms of Th1-induced airway inflammation. Airway inflammation was induced in BALB/c mice by transfer of freshly induced OVA-specific Th1 or Th2 cells followed by OVA inhalation. In this model, both Th1 and Th2 cells induced airway inflammation. The former induced neutrophilia in airways, whereas the latter induced eosinophilia. Moreover, we found that Th1 cells induced more severe airway hyperresponsiveness (AHR) than Th2 cells. The eosinophilia induced by Th2 cell infusion was almost completely blocked by administration of anti-IL-5 mAb, but not anti-IL-4 mAb. In contrast, Th1-induced AHR and pulmonary neutrophilia were inhibited by the administration of anti-human IL-8R Ab, which blocks the function of mouse CXC chemokine(s). These findings reveal a critical role of mouse CXC chemokine(s) in Th1-dependent pulmonary neutrophilia and AHR.

Administration, Inhalation↗

PubMed2001

High production of interferon gamma but not interleukin-2 by human T-lymphotropic virus type I-infected peripheral blood mononuclear cells.

The transactivator protein of human T-lymphotropic virus I (HTLV-I), Tax, has been associated with the up-regulation of several host cell genes, including interleukin 2 (IL-2), the IL-2 receptor-alpha (IL-2Ralpha) chain (CD25), interferon gamma (IFN-gamma), and tumor necrosis factor (TNF). It has been proposed that an IL-2/CD25 autocrine loop plays a part in maintaining the very high proviral loads often found in HTLV-I infection. Furthermore, abnormal production of inflammatory cytokines might contribute to the pathogenesis of the inflammatory diseases associated with HTLV-I infection. However, there has been no study of the expression of these genes in freshly isolated peripheral blood mononuclear cells (PBMCs) naturally infected with HTLV-I. In the present study, flow cytometry was used to determine which cytokines are produced by freshly isolated PBMCs that spontaneously express the HTLV-I Tax protein. Surprisingly, the results show that intracellular Tax expression is associated with rapid up-regulation of IFN-gamma but not TNF or IL-2. A proportion of HTLV-I-infected cells express both IFN-gamma and the surface markers of effector memory cells. Such cells are capable of migration through peripheral tissues and could therefore contribute to the inflammation seen in diseases such as HTLV-I-associated myelopathy/tropical spastic paraparesis. (Blood. 2001;98:721-726)

Cytokines↗

PubMed2001

CD44 is the physiological trigger of Fas up-regulation on rheumatoid synovial cells.

CD44 is a ubiquitous molecule known as a hyaluronan receptor. However, the relevance of CD44 to inflammatory processes, for example, rheumatoid synovitis, remains unclear. In this study, we propose a novel function for CD44 using synovial cells from rheumatoid arthritis (RA) patients and demonstrated that CD44 cross-linking augmented Fas expression and subsequent Fas-mediated apoptosis of the cells: 1) cross-linking of CD44 on RA synovial cells markedly augmented Fas expression and its mRNA transcription; 2) engagement of CD44 up-regulated Fas on the cells within 3 h, much more than IL-1beta and TNF-alpha did; 3) the Fas-mediated early apoptotic change of the cells was amplified by CD44 cross-linking; and 4) hyaluronan, especially when fragmented, also augmented Fas-mediated early apoptosis of the cells. Based on these findings, we postulate a new concept: that interaction of CD44 on RA synovial cells with hyaluronan fragments present in the surrounding extracellular matrix augments Fas expression as well as Fas-mediated apoptosis of synovial cells. This may lead to spontaneous growth arrest through Fas-Fas ligand pathway observed in synovial cells of RA synovitis in vivo.

Adjuvants, Immunologic↗

PubMed2001

Hepatoma-derived growth factor is associated with reduced sensitivity to irradiation in esophageal cancer.

Radiotherapy is a useful component of treatment for esophageal cancer. Identification of the genes that are differentially expressed between radiosensitive and radioresistant cancer cells is important for predicting clinical effectiveness of radiotherapy. We established human esophageal cancer cell lines resistant to X-ray. Using differential display, we obtained one gene that was expressed in radiosensitive cells but was rarely expressed in radioresistant cells, and that gene was identical with hepatoma-derived growth factor (HDGF), an acidic polypeptide with mitogenic activity for fibroblasts. The semiquantitative reverse transcription-PCR assay confirmed that HDGF mRNA expression was reduced in established radioresistant cells, and its reduction was associated with reduced sensitivity to irradiation. Radiotherapy was more effective in clinical cases with high HDGF mRNA expression compared with cases with low expression (P < 0.05). The findings demonstrate that HDGF may play an important role in radiosensitivity, and it could be a novel marker predicting effectiveness of radiotherapy in clinical cases.

Adult↗

PubMed2001

Halotolerant cyanobacterium Aphanothece halophytica contains an Na(+)/H(+) antiporter, homologous to eukaryotic ones, with novel ion specificity affected by C-terminal tail.

Recently, a cyanobacterium Synechocystis sp. PCC 6803 has been shown to contain an Na(+)/H(+) antiporter gene homologous to plants (SOS1 and AtNHX1 from Arabidopsis) and mammalians (NHEs from human) but not to Escherichia coli (nhaA and nhaB). Here, we examined whether a halotolerant cyanobacterium Aphanothece halophytica has homologous genes. It turned out that A. halophytica contains an Na(+)/H(+) antiporter homologous to plants, mammalians, and some bacteria (nhaP from Pseudomonas and synnhaP from Synechocystis) but with novel ion specificity. Its gene product, ApNhaP (Na(+)/H(+) antiporter from Aphanothece halophytica), exhibited the Na(+)/H(+) antiporter activity over a wide pH range between 5 and 9 and complemented the Na(+)-sensitive phenotype of the antiporter-deficient E. coli mutant. The ApNhaP had virtually no activity for the Li(+)/H(+) antiporter but showed high Ca(2+)/H(+) antiporter activity at alkaline pH. The ApNhaP complemented the Ca(2+)-sensitive phenotype of the E. coli mutant but not the Li(+)-sensitive phenotype. The replacement of a long C-terminal tail of ApNhaP with that of Synechocystis altered the ion specificity of the antiporter. These results suggest that the ion specificity of an Na(+)/H(+) antiporter is partly determined by the structural properties of the C-terminal tail, which was well exemplified in the case of A. halophytica.

Amino Acid Sequence↗

PubMed2001

Ionization of dichlorophenols for their analysis by capillary electrophoresis-mass spectrometry.

In order to develop an advanced analytical method using capillary electrophoresis (CE) for non-volatile environmental pollutants such as endocrine disruptors, combination with mass spectrometry (MS) is necessary for their identification. We chose dichlorophenols (DCPs) as test samples because one of their isomers, 2,4-DCP, is suspected to have endocrine disrupting effects. A preliminary study on their separation by CE-MS was performed using a laboratory-made electrospray ionization (ESI) interface. For the effective ionization of 2,4-DCP at the

Chlorophenols↗

PubMed2001

The expression of vascular endothelial growth factor C and its receptors in non-small cell lung cancer.

Expression of vascular endothelial growth factor (VEGF)-C and that of its receptors were assessed in non-small cell lung cancer. Immunohistochemistry revealed positive VEGF-C expression in 38.7% (24/62) of the patients studied. A significant positive correlation was found between VEGF-C in cancer cells and VEGF receptor-3 (VEGFR-3) in vascular endothelial cells, but not between VEGF-C in cancer cells and VEGFR-2 in endothelial cells. In this cohort of lung cancer patients, VEGF-C expression was significantly associated with lymph node metastasis, lymphatic vessel invasion, and worse outcomes after the operation. Although the independent prognostic impact of VEGF-C and VEGFR-3 was not clear, VEGFR-2 expression in endothelial cells retained the independency as the prognostic indicator. In light of these findings, we conclude that VEGF-C plays an important role in lymphatic invasion/metastasis and tumour progression in non-small cell lung cancer.

Aged↗

PubMed2001

Inhibition of prostaglandin synthesis by nitric oxide in RAW 264.7 macrophages.

Multiple effects of nitric oxide (NO) were revealed on the inhibition of prostaglandin (PG) synthesis by a macrophage-like cell line, RAW 264.7 cells, treated with lipopolysaccharide (LPS). NO-generating reagent, N-ethyl-2-(1-ethyl-2-hydroxy-2-nitrosohydrazino)ethanamine (NOC 12), inhibited the release of PG from cells with LPS treatment at higher concentrations although it stimulated the release at 50 microM. PGH synthase (PGHS) activity in the microsome fraction of the LPS-treated cells was inhibited by (+/-)-(E)-methyl-2-[(E)-hydroxyimino]-5-nitro-6-methoxy-3-hexeneamine (NOR 1), another NO-generating reagent, dose dependently. NOC 12 also dose dependently inhibited PG synthesis from exogenous arachidonic acid in those cells. On the other hand, NOC 12 increased PGHS-2 mRNA, while it increased the PGHS-2 protein at concentrations lower than 200 microM or decreased it at higher concentrations. These results suggest that the effect of NO on PGs synthesis in LPS-treated macrophage cells is mainly due to the balance of its stimulations of the transcriptional and/or translational expression of PGHS-2 and the inhibition of the induced PGHS-2 activity.

Animals↗

PubMed2001

Plasma monocyte chemoattractant protein-1 and pulmonary vascular resistance in chronic thromboembolic pulmonary hypertension.

The pathogenesis of severe pulmonary hypertension seems to be related to inflammatory response in diseased sites. Monocyte chemoattractant protein-1 (MCP-1) has been reported to play a role in the development of congestive heart failure. In this immunological response, activation and migration of leukocytes including macrophages to the inflammatory region are important factors. We hypothesized that the severity of pulmonary hypertension may be related to MCP-1, which is thought to be upregulated by blood pressure or shear stress in pulmonary vasculature as well as by immunological and inflammatory reactions in chronic thromboembolic pulmonary hypertension (CTEPH). Circulating levels of MCP-1, interleukin-1beta (IL-1beta), and tumor necrosis factor-alpha (TNF-alpha) were measured by sandwich ELISA in 14 patients with CTEPH. The plasma level of MCP-1 was significantly correlated with pulmonary vascular resistance. In IL-1beta and TNF-alpha, on the other hand, there was no correlation between cytokines and pulmonary hemodynamics. Pathological specimens obtained from the patients with CTEPH undergoing thromboendarterectomy demonstrated immunoreactivity of MCP-1 in endothelium, smooth muscle cells, and macrophages within neointima in the hypertensive large elastic pulmonary artery. We conclude that MCP-1 is upregulated in the remodeling of pulmonary arteries in close association with increased pulmonary vascular resistance in CTEPH.

Adult↗

PubMed2001

Functional CD4 T cells after intercellular molecular transfer of 0X40 ligand.

OX40/OX40 ligand (OX40L) proteins play critical roles in the T cell-B cell and T cell-dendritic cell interactions. Here we describe the intercellular transfer of OX40L molecules by a non-Ag specific manner. After 2-h coculture of activated CD4(+) T cell (OX40L(-), OX40(+)) with FLAG peptide-tagged OX40L (OX40L-flag) protein-expressing COS-1 cells, the OX40L-flag protein was detected on the cell surface of the CD4(+) T cells by both anti-OX40L and anti-FLAG mAbs. The intercellular OX40L transfer was specifically abrogated by pretreatment of the COS-1 cells with anti-OX40L mAb, 5A8. The OX40L transfer to OX40-negative cells was also observed, indicating an OX40-independent pathway of OX40L transfer. HUVECs, allostimulated monocytes, and human T cell leukemia virus type I-infected T cells, which all express OX40L, can potentially act as the donor cells of OX40L. The entire molecule of OX40L was transferred and stabilized on the recipient cell membrane with discrete punctate formation. The transferred OX40L on normal CD4(+) T cells was functionally active as they stimulated latent HIV-1-infected cells to produce viral proteins via OX40 signaling. Therefore, these findings suggest that the intercellular molecular transfer of functional OX40L may be involved in modifying the immune responses.

Animals↗

PubMed2001

Thermo-responsive release from interpenetrating porous silica-poly(N-isopropylacrylamide) hybrid gels.

Novel thermo-responsive inorganic-organic hybrid gels were prepared by hybridizing porous silica and poly(N-isopropylacrylamide) gels (PNIPAAm gel). The internal pores of the silica were filled with PNIPAAm gel to give a thermo-responsive drug reservoir. Brilliant blue FCF (BB) was also added to the hybrid gels for release. The BB release rate was faster above the lower critical solution temperature (LCST) of the PNIPAAm gel than below the LCST. When the temperature changed across the LCST, reversible and thermo-responsive release behavior was observed. The transition of the release behavior upon changing the temperature was similar to the behavior of the PNIPAAm gel itself. The BB release rate can be controlled simply by changing the amount of PNIPAAm gel loaded into the silica.

Acrylic Resins↗

PubMed2001

Effects of histamine H3-receptor ligands on brain monoamine oxidase in various mammalian species.

The effects of an H3 agonist, R-alpha-methylhistamine (alpha-MeHA), and an H3 antagonist, thioperamide, on monoamine oxidase (MAO) activity in the hypothalamus of rat, monkey and human brains were compared in vitro. The histamine H(3)-receptor ligands competitively inhibited MAO-B, but noncompetitively inhibited MAO-A in all three mammalian species. However, alpha-MeHA inhibited MAO-A more potently than MAO-B at high concentrations in all three species. The K(i) values for MAO-A of alpha-MeHA in hypothalamic homogenates of rat, monkey and human brains were estimated to be 1.1, 1.2 and 1.9 mM, respectively, suggesting that alpha-MeHA cannot behave as a substrate for the MAO inhibitor. In contrast, rat, monkey and human brain MAO-B activities were inhibited by thioperamide, with respective K(i) values of 174.6, 8.2 and 10.8 microM, more potently than MAO-A activity. These results indicate that thioperamide, which elicits a strong activation of histamine release and turnover to N-tele-methylhistamine from histamine, competitively inhibits the conversion of N-tele-methylhistamine to N-tele-methylimidazoleacetic acid in human and monkey brains where MAO-B predominates.

Aged↗

PubMed2001

Self-assembly of a porphyrin array via the molecular recognition approach: synthesis and properties of a cyclic zinc(II) porphyrin trimer based on coordination and hydrogen bonding.

Self-assembly of [5-(pyrazol-4-yl)-10,20-bis(p-tolyl)-15- (2-ethoxycarbonylphenyl)porphyrinato]-zinc(II) (1), designed to have both a coordination site and a hydrogen bonding site, leads to a stable cyclic trimer array where coordination of the pyrazole nitrogen to the zinc(II) ion as well as hydrogen bonding between carbonyl oxygen and pyrazole NH holds each zinc(II) porphyrin. The recognition event for pyrazole has been confirmed preliminarily in the model studies using [5-(2-ethoxycarbonylphenyl)tris(p-tolyl)porphyrinato]-zinc(II) (3). The zinc(II) porphyrin 3 has large affinity for pyrazole due to the hydrogen bond between pyrazole and the 2-ethoxycarbonyl group in addition to the coordination bonding accompanied by the conformational change of the ethoxycarbonyl group in the coordination process. The (1)H NMR, IR, and UV-vis spectra of 1 and its ESI-MS and VPO measurements have revealed the cyclic trimer structure with an overall association constant of 6.0 x 10(13) M(-2) at 22 degrees C. The contribution of the hydrogen bond to the total free energy change in trimer formation is estimated to be 7.5 kcal/mol based on a reference trimer system without a hydrogen bonding site. The trimer geometry causes characteristic exitonic interaction between porphyrin units to yield a broad Soret band which is deconvoluted into four components by UV-vis and MCD spectral analyses. Electrochemical measurements have shown that only the first ring-oxidation process proceeds stepwise in the trimer.

Electrochemistry↗

PubMed2001

Expression of the glucose transporter gene, ptsG, is regulated at the mRNA degradation step in response to glycolytic flux in Escherichia coli.

We report a novel post-transcriptional control of the ptsG gene encoding the major glucose transporter IICB(Glc). We demonstrate that the level of IICB(Glc) is markedly reduced when the glycolytic pathway is blocked by a mutation in either the pgi or pfkA gene encoding phosphoglucose isomerase or phosphofructokinase, respectively. This down-regulation of ptsG is not exerted at the transcriptional level. Both northern blot and S1 analyses demonstrate that the mutation dramatically accelerates the degradation of ptsG mRNA. The degradation of ptsG mRNA occurs in wild-type cells when alpha-methylglucoside, a non- metabolizable analog of glucose, is present in the medium. The addition of any one of the glycolytic intermediates downstream of the block prevents the degradation of ptsG mRNA. The rapid degradation of ptsG mRNA is eliminated when RNase E is thermally inactivated. We conclude that the glycolytic pathway controls ptsG expression by modulating RNase E-mediated mRNA degradation. This is the first instance in which the glycolytic flux has been shown to affect the expression of a specific gene through mRNA stability.

Citric Acid Cycle↗

PubMed2001

Structural features of nonpeptide prenyl pyrophosphates that determine their antigenicity for human gamma delta T cells.

Human Vgamma2Vdelta2(+) T cells proliferate in vivo during many microbial infections. We have found that Vgamma2Vdelta2(+) T cells recognize nonpeptide prenyl pyrophosphates and alkylamines. We now have defined structural features that determine the antigenicity of prenyl pyrophosphates by testing synthetic analogs for bioactivity. We find that the carbon chain closest to the pyrophosphate moiety plays the major role in determining bioactivity. Changes in this area, such as the loss of a double bond, abrogated bioactivity. The loss of a phosphate from the pyrophosphate moiety also decreased antigenicity 100- to 200-fold. However, nucleotide monophosphates could be added with minimal changes in bioactivity. Longer prenyl pyrophosphates also retained bioactivity. Despite differences in CDR3 sequence, Vgamma2Vdelta2(+) clones and a transfectant responded similarly. Ag docking into a Vgamma2Vdelta2 TCR model reveals a potential binding site in germline regions of the Vgamma2Jgamma1.2 CDR3 and Vdelta2 CDR2 loops. Thus, Vgamma2Vdelta2(+) T cells recognize a core carbon chain and pyrophosphate moiety. This recognition is relatively unaffected by additions at distal positions to the core Ag unit.

Adult↗

PubMed2001

Identification of human liver diacetyl reductases by nano-liquid chromatography/Fourier transform ion cyclotron resonance mass spectrometry.

Several forms of diacetyl-reducing enzyme were found to exist in the human liver cytosol. Three (DAR-2, DAR-5, and DAR-7) of them were purified as a single band on SDS-PAGE by a combination of a few kinds of column chromatographies. The in-gel tryptic digests of the purified enzymes were analyzed by nano-liquid chromatography (LC)/Fourier transform ion cyclotron resonance mass spectrometry (FT ICR MS), which provided peptide masses at a ppm-level accuracy. The enzymes, DAR-2, DAR-5, and DAR-7, were identified as alcohol dehydrogenase beta subunit (ADH2), carbonyl reductase (CBR1), and aldehyde reductase (AKR1A1), respectively, by peptide mass fingerprinting. In addition, an alternating-scan acquisition of nano-LC/FT ICR mass spectra, i.e., switching of normal acquisition conditions and in-source fragmentation conditions scan by scan, provided sets of parent and fragment ion masses of many of the tryptic peptides in a single LC/MS run. The peptide sequence-tag information at the ppm-level accuracy was used to further confirm the protein identities. It was demonstrated that nano-LC/FT ICR MS can be used for rigorous protein identification at a subpicomole level as an alternative technique to nano-LC/MS/MS.

Acetoin Dehydrogenase↗