Biomedical subjects

M Azuma

Publications and source records attributed to M Azuma.

At least 73 records · Page 4Linked to original sources

PubMed2001

Activity of anthocyanins from fruit extract of Ribes nigrum L. against influenza A and B viruses.

Earlier, we have detected antiviral activity in an extract from Ribes nigrum L. fruits ("Kurokarin", name of the one species of black currant in Japanese) against influenza A and B viruses, and herpes simplex virus 1 (Knox et al., Food Processing 33, 21-23, 1998). In the present study, the antiviral activity of constituents of a Kurokarin extract and the mechanism of its antiviral action were examined. Kurokarin extracts were separated to fractions A to D by column chromatography. The major constituents of the fraction D were estimated as anthocyanins. The fraction D was further fractionated by thin-layer chromatography (TLC) to fractions A' to G'. The fraction E' consisted of 3-O-alpha-L-rhamnopyranosyl-beta-D-glucopyranosyl-cyanidin and 3-O-beta-D-glucopyranosyl-cyanidin, and the fraction F' consisted of 3-O-alpha-L-rhamnopyranosyl-beta-D-glucopyranosyl-delphinidin and 3-O-beta-D-glucopyranosyl-delphinidin, identified by high performance liquid chromatography (HPLC) with standards and by high resolution mass spectrometry. The fractions D' to G' showed potent antiviral activity against influenza viruses A and B. The additive antiviral effect of a combination of the fractions E' and F' was assessed. Anthocyanins in the fraction F' did not directly inactivate influenza viruses A and B, but they inhibited virus adsorption to cells and also virus release from infected cells.

Animals↗

PubMed2000

Taurine attenuates hypertrophy induced by angiotensin II in cultured neonatal rat cardiac myocytes.

The effect of taurine on angiotensin II-induced changes in cell morphology and biochemistry of the cultured neonatal cardiomyocyte was examined. Angiotensin II (1-100 nM) alone caused a slow increase in the surface area of the myocyte accompanied by an induction of the expression of atrial natriuretic peptide (ANP) and an upregulation of transforming growth factor beta(1) gene (TGF-beta(1)). The signaling pathway of angiotensin II (1-100 nM) was found to proceed through protein kinase C and the rapid activation of mitogen-activated protein (MAP) kinases. Pretreatment of the myocyte with taurine (20 mM) in the absence of angiotensin II had no visible effect on cell size or growth rate. However, the cells that were pretreated with taurine (20 mM) for 24 h exhibited reduced responsiveness to angiotensin II (100 nM) relative to surface cell area enlargement and the upregulation of the late and growth factor genes(ANP, TGF-beta(1)). Angiotensin II-mediated activation of the MAP kinases (extracellular signal-regulated protein kinase 1/2: ERK1/2) was not blocked by taurine. Taurine reduced the phosphorylation of a 29-kDa protein, a reaction which was enhanced by angiotensin II and appears to involve protein kinase C step. The results indicate that taurine is an effective inhibitor of certain aspects of angiotensin II action.

Angiotensin II↗

PubMed2000

Evidence for apoptosis in the selenite rat model of cataract.

The purposes of this experiment were (1) to determine if apoptosis was accelerated during formation of selenite cataract, and (2) to determine the role of calpains and caspases in lens apoptosis. Evidence for apoptosis in selenite-injected rats included: approximately 7-8% of epithelial cells in germinative zone were positive, disappearance of the nuclear membrane, condensation of the chromatin, and breakdown of PARP. Activation of calpains was indicated by characteristic limited proteolysis of crystallins, breakdown of alpha-spectrin to 150/145 kDa fragments, hydrolysis of vimentin, and autolytic breakdown of m-calpain. Selenite cataract did not have an appreciable effect on the mRNA levels for caspase-3, calpains, and calpastatin. This indicated the increased enzyme activity of m-calpain and caspase-3 in selenite cataract occurred at the enzyme level rather than by upregulation of mRNAs. Increased calpain and caspase activity may be linked to the selenite-induced apoptosis. Such data are important because they indicate that apoptosis may be a fairly early event in selenite cataract.

Animals↗

PubMed2000

Crossover from dilute to majority spin freezing in two leg ladder system Sr(Cu,Zn)2O3

Muon spin relaxation has been measured in Sr(Cu1-xZnx)2O3. The results for low Zn concentration x</=0.6% are consistent with freezing of dilute moments, with one Cu spin for each Zn, having approximately 0.5&mgr;(B) frozen moment. A sharp increase of the relaxation rate at T-->0 occurred with increasing x around x approximately 0.8%, accompanied by a change of line shape to that expected in a concentrated magnetic environment. Analyses of the results for x>/=0.8% suggest that the majority of Cu moments participate in spin freezing, yet with a significantly reduced and spatially inhomogeneous moment size having a 1D correlation length xi approximately 6 lattice units, or a 2D correlation area involving approximately 19 Cu spins.

Journal Article↗

PubMed2000

Autoantigen-specific CD4+CD28low T cell subset prevents autoimmune exocrinopathy in murine Sjögren's syndrome.

Organ-specific autoimmune exocrinopathy resembling Sjögren's syndrome (SS) that spontaneously develops in NFS/sld mutant mice thymectomized 3 day after birth is dependent on Th1-type CD4+ T cells. We previously reported that a cleavage product of 120-kDa alpha-fodrin may be an important autoantigen in the pathogenesis of SS in both an animal model and the patients. We demonstrate that in an animal model of SS with overt exocrinopathy, a unique CD4+ T cell subset expressing CD28low is dramatically increased in spleen cells before the disease onset, but that the CD4+ T cells of diseased mice were virtually all CD28high. We found that the spleen cells in these mice before the disease onset showed a significant increase in autoantigen-specific T cell proliferation. Analysis of in vitro cytokine production by spleen cells indicated, before the disease onset, severely impaired production of IL-2 and IFN-gamma in the animal model, whereas high levels of IL-4 were observed. Expression of cytokine genes, including IL-4, IL-10, and TGF-beta, was detected in FACS-sorted CD4+CD28low T cells by RT-PCR analysis. Transfer of CD4+CD28low T cells into the animal model actually prevented the development of autoimmune lesions including autoantibody production. These results suggest that a CD4+CD28low T cell subset that is continuously activated by an organ-specific autoantigen may play a regulatory role in the development of organ-specific autoimmune disease in an animal model of SS.

Adoptive Transfer↗

PubMed2000

5-Fluorouracil induces apoptosis through the suppression of NF-kappaB activity in human salivary gland cancer cells.

Activation of the transcription factor NF-kappaB results in protection against apoptosis, and the chemotherapeutic agent 5-Fluorouracil (5-FU) exerts its cytotoxic effect through the induction of apoptosis. Thus, we examined whether 5-FU could induce apoptosis through the suppression of NF-kappaB activity. We found that upon treatment of a human salivary gland cancer cell line (cl-1) with 5-FU, the NF-kappaB activity was suppressed in a time-dependent manner. This inhibition was mediated by a prevention of the degradation of the inhibitory IkappaB-alpha protein. In addition, the expression of TRAF-2 and cIAP-1, which are transcriptionally regulated by NF-kappaB and function as anti-apoptotic molecules through the interruption of caspase pathway, was also inhibited by 5-FU. Finally, the activity of caspase-8 and caspase-3 showed a significant increase in response to 5-FU. By flow cytometric analysis, 5-FU did not affect the expression level of Fas on the cell surface. Thus, our results suggest that one of the molecular mechanisms involved in 5-FU-induced apoptosis in cl-1 cells may be due to the suppression of NF-kappaB activity, resulting in the activation of the pro-apoptotic pathway.

Antimetabolites, Antineoplastic↗

PubMed2000

Enterotoxin adjuvants have direct effects on T cells and antigen-presenting cells that result in either interleukin-4-dependent or -independent immune responses.

In an in vitro study, Escherichia coli heat-labile toxin (LT) was shown to directly affect activated CD4(+) T cells and support interleukin (IL)-5 production in IL-4-deficient (IL-4(-/-)) mice, whereas cholera toxin (CT) did not. Both LT and CT enhanced B7-2 expression on B cells and macrophages. These effects were not influenced by CD40-CD40 ligand cosignaling. Addition of LT- or CT-treated antigen-presenting cells to anti-CD3-triggered CD4(+) T cells resulted in the induction of T cell proliferative responses. Further, these responses were inhibited by anti-B7-2 monoclonal antibody. Cocultivation of CD4(+) T cells with LT- or CT-treated antigen-presenting cells and anti-CD3 enhanced Th1- and IL-4-mediated Th2-type cytokine production. The results from in vitro studies were supported by in vivo studies in IL-4(-/-) mice, in which LT induced mucosal IgA responses but CT did not. Thus, although both LT and CT induce mucosal adjuvant responses via IL-4-dependent Th2-type responses, LT also elicits Th1- and IL-4-independent Th2-type responses.

Animals↗

PubMed2000

Light intensity distribution in the externally illuminated cylindrical photo-bioreactor and its application to hydrogen production by Rhodobacter capsulatus.

The light distribution in the externally illuminated cylindrical photo-bioreactor for production of hydrogen by a photosynthetic bacterium Rhodobacter capsulatus ST-410 was estimated. The estimation was performed on the basis of the Matsuura and Smith's diffuse model [1]. In the diffuse model, the incident light rays are assumed to proceed in every direction and the local intensity is calculated as the sum of the intensities of light. Since Lambert-Beer's law, extensively used in photometry, was not useful for explaining the decrease in the intensity of light by the biomass, an empirical expression was used. The measurement of the intensities from every direction was conducted in an externally illuminated cylindrical photo-bioreactor having an inner diameter of 60mm and a working volume of 550ml. The obtained results confirmed our estimation. The light distribution was applied to estimate the hydrogen production by R. capsulatus ST-410 using the same photo-bioreactor. The overall hydrogen-production rate was successfully estimated.

Journal Article↗

PubMed2000

63Cu NQR evidence of dimensional crossover to anisotropic 2D regime in S = 1 / 2 three-Leg ladder Sr2Cu3O5

We probed spin-spin correlations up to 725 K with 63Cu nuclear quadrupole resonance in the S = 1 / 2 three-leg ladder Sr2Cu3O5. We present experimental evidence that below 300 K weak interladder coupling causes dimensional crossover of the spin-spin correlation length xi from the quasi-1D (xi approximately 1 / T) to the anisotropic 2D regime ( xi approximately exp2pirho(s) / T, where 2pirho(s) = 290+/-30 K is the effective spin stiffness).

Journal Article↗

PubMed2000

Blockade of CTLA-4 signals inhibits Th2-mediated murine chronic graft-versus-host disease by an enhanced expansion of regulatory CD8+ T cells.

CTLA-4 (CD152) is thought to be a negative regulator of T cell activation. Little is known about the function of CTLA-4 in Th2-type immune responses. We have investigated the effect of initial treatment with anti-CTLA-4 mAb on murine chronic graft-vs-host disease. Transfer of parental BALB/c splenocytes into C57BL/6 x BALB/c F1 mice induced serum IgE production, IL-4 expression by donor CD4+ T cells, and host allo-Ag-specific IgG1 production at 6-9 wk after transfer. Treatment with anti-CTLA-4 mAb for the initial 2 wk significantly reduced IgE and IgG1 production and IL-4 expression. Analysis of the splenic phenotype revealed the enhancement of donor T cell expansion, especially within the CD8 subset, and the elimination of host cells early after anti-CTLA-4 mAb treatment. This treatment did not affect early IFN-gamma expression by CD4+ and CD8+ T cells and anti-host cytolytic activity. Thus, blockade of CTLA-4 greatly enhanced CD8+ T cell expansion, and this may result in the regulation of consequent Th2-mediated humoral immune responses. These findings suggest a new approach for regulating IgE-mediated allergic immune responses by blockade of CTLA-4 during a critical period of Ag sensitization.

Abatacept↗

PubMed2000

Stat6 activation and Th2 cell differentiation [correction of proliferation] driven by CD28 [correction of CD28 signals].

CD28 engagement by specific monoclonal antibody (mAb) or binding of the natural ligands, CD80 and CD86, induces tyrosine phosphorylation of CD28, which in turn recruits and activates the signal transducer and activator of transcription 6 (Stat6). The Stat6 association with CD28 is specifically induced by CD80 or CD86 ligand binding and is not dependent upon the secretion of IL-4 or IL-13. Activated Stat6 translocates to the nucleus and binds to a Stat6-responsive element on the human IL-4 promoter. CD28 ligation induces Stat6-dependent transcriptional activation of a reporter gene under the control of a multimerized Stat6-responsive element fused to an essential part of the IL-4 promoter. Primary stimulation of naive CD4(+) T cells with anti-CD28 mAb in the presence of IL-2, but in the absence of anti-CD3 mAb induces preferential production of IL-4 and expression of CCR4 mRNA after secondary stimulation with anti-CD3, indicating the preferential differentiation of Th2 cells. These findings suggest that initial IL-4 production required for commitment of naive T cells toward Th2 cells may be provided in response to signals delivered via CD28 by antigen-presenting cells.

Animals↗

PubMed2000

Effect of D-glucose on induction of xylose reductase and xylitol dehydrogenase in Candida tropicalis in the presence of NaCl.

Xylitol production is suppressed by D-glucose. We previously reported that the suppression was abrogated in the presence of NaCl. This was explained in part by high levels of xylose reductase (XR) activity. In this study, we investigated the effects of D-glucose on XR and xylitol dehydrogenase (XDH) induction in Candida tropicalis in the presence of NaCl. We examined the time courses of these activities under the following conditions: 50 mg/ml D-xylose, 20-80 mg/ml D-glucose and 40 mg/ml NaCl. The level of XR increased in the presence of 40 mg/ml NaCl, whereas that of XDH was not affected by NaCl. The effects of NaCl upon XR and XDH induction suggest that the synthesis of both enzymes is not under a coordinate control. The expression of XR is suppressed by D-glucose. In the absence of NaCl, suppression continued even after D-glucose was completely consumed, while in the presence of 40 mg/ml NaCl, suppression stopped after the consumption of D-glucose.

Aldehyde Reductase↗

PubMed2000

Cytokines production of U5A2-13-positive T cells by stimulation with glycolipid alpha-galactosylceramide.

We have previously established and reported a novel monoclonal antibody (mAb), U5A2-13, which recognizes a phenotypically similar population of natural killer (NK)-like T cells. Using U5A2-13 mAb, we now describe the functional properties of U5A2-13(+) T cells in both NK1.1-positive or -negative mouse strains. Similar to NK1.1(+) T cells, hepatic U5A2-13(+) T cells of C57BL/6 (NK1.1(+) strain) mice, but not U5A2-13(-) T cells, could be induced to produce large amounts of IL-4 and IFN-gamma by stimulation with glycolipid alpha-galactosylceramide (alpha-GalCer) present on dendritic cells (DC) in a dose-dependent manner. The abundant production of these cytokines from U5A2-13(+) T cells of BALB/c (NK1.1(-) strain) mice is similar to that noted in C57BL/6 mice. Cytokine production by cultures stimulated with DC of beta2-microglobulin-deficient mice was significantly less than that of cultures stimulated with DC of intact mice. Overall, U5A2-13(+) T cells recognize alpha-GalCer presented by CD1d, indicating that U5A2-13(+) T cells can be used to analyze NK-like T cell function in various strains of mice.

Animals↗

PubMed2000

Suppression of tumor necrosis factor alpha-induced matrix metalloproteinase 9 production by the introduction of a super-repressor form of inhibitor of nuclear factor kappaBalpha complementary DNA into immortalized human salivary gland acinar cells. Prevention of the destruction of the acinar structure in Sjögren's syndrome salivary glands.

OBJECTIVE: We have previously shown that specific enhancement in acinar cells of proteolytic activity induced by tumor necrosis factor alpha (TNFalpha) may be responsible for the destruction of the acinar structure in the salivary glands of patients with Sjögren's syndrome. Because matrix metalloproteinase 9 (MMP-9) is regulated by nuclear factor kappaB (NF-kappaB), we investigated the effect of a super-repressor form of inhibitor of nuclear factor kappaBalpha (srIkappaBalpha) on the suppression of TNFalpha-induced MMP-9 production in acinar cells. METHODS: Two srIkappaBalpha complementary DNA (cDNA)-transfected acinar cell clones (ACMT-6 and ACMT-7) and 1 empty vector-transfected cell clone (ACpRc-1) were established. After treatment of cell clones with TNFalpha, the expression of MMP-9 was examined. In addition, the effect of TNFalpha on cell growth and the morphogenetic behavior of cell clones cultured on type IV collagen-coated dishes were examined. RESULTS: TNFalpha induced the production of MMP-9 in the ACpRc-1 cell clone, but greatly suppressed MMP-9 production in ACMT-6 and ACMT-7 clones. No apparent cytotoxic effect of TNFalpha treatment was observed in these cell clones. When ACpRc-1 cells were seeded on type IV collagen-coated dishes in the presence of both TNFalpha and plasmin, type IV collagen interaction with the cells was lost and the cells entered apoptosis. However, even when ACMT-6 and ACMT-7 cells were cultured under the same culture conditions as those for ACpRc-1, these cell clones attached to the substrate and grew consistently without showing apoptosis. Conclusion. These observations indicate that suppression of TNFalpha-induced MMP-9 production by the introduction of srIkappaBalpha cDNA corrected the aberrant in vitro morphogenesis of acinar cells grown on type IV collagen.

Blotting, Western↗

PubMed2000

Progress reports on immune gene therapy for stage IV renal cell cancer using lethally irradiated granulocyte-macrophage colony-stimulating factor-transduced autologous renal cancer cells.

There is no effective treatment for patients with stage IV renal cell cancer (RCC), although the introduction of new therapy is imminent. Cancer gene therapy is currently considered to be one of the most promising therapeutic modalities in the field of cancer treatment. Based on the results of animal studies, vaccination using autologous granulocyte-macrophage colony-stimulating factor-transduced renal cancer cells appears promising. Before initiating a clinical study using an ex vivo gene-transduced autologous cell vaccine-based immunogene therapy for RCC in Japan, in 1992 we initially planned a Japanese version of a clinical protocol in collaboration with a US group. In 1993, the original protocol was refined. We performed five preclinical qualification studies using RCC nephrectomy specimens from patients in 1997, and the results showed that preparation of RCC cells for autologous vaccines at the Clinical Cell Technology Facility, Research Hospital of the Institute of Medical Science, University of Tokyo, was feasible. Subsequently in August 1998, the Ministry of Health and Welfare and the Ministry of Education, Science, Culture, and Sport approved our clinical protocol. We have recruited two patients with stage IV RCC to our study so far. Here we report the background to the initiation of cancer gene therapy in Japan.

Adult↗

PubMed2000

Susceptibility of protein kinase (ORF47)-deficient varicella-zoster virus strains to anti-herpesvirus nucleosides.

To clarify whether varicella-zoster virus (VZV) protein kinase (PK; ORF47) takes part in phosphorylation of anti-herpesvirus nucleosides, thymidine kinase (TK) deficient, and PK/TK double deficient recombinant VZV strains were isolated and their susceptibility, and that of wild type and PK-deficient strains to various nucleoside analogs was evaluated. The PK-deficient VZV strains showed a sensitivity equal to that of the wild type strain against all compounds tested, including ganciclovir. This indicates that PK is not involved in phosphorylation of the tested nucleosides in VZV-infected cells.

Antiviral Agents↗

PubMed2000

A synthetic peptide of human apoprotein E with antibacterial activity.

In recent years, several endogenous mammalian antibacterial peptides have been described. An amphipathic cationicalpha-helix is a common feature in many cases; therefore, other peptides with this characteristic might also possess antibiotic activity. In fact, a 30-mer peptide of apoprotein E 133-162 (LRVRLASHLRKLRKRLLRDADDLQKRLAVY) was found to have antibiotic activity comparable to those of a classic antibiotic (Gentamicin) and a neutrophil-derived antibiotic peptide (CAP18). Calculation of cationicity, hydrophobicity, and hydrophobic moment and the helical wheel diagram of apoprotein E 133-162 revealed close similarities to CAP18.

Amino Acid Sequence↗

PubMed2000

Fas/Fas ligand-mediated apoptosis of murine Langerhans cells.

Epidermal Langerhans cells (LC) are potent antigen-presenting cells (APC), that play a crucial role in initiating cutaneous immune responses. The Fas/Fas ligand pathway has been implicated as an important cellular pathway in the regulation of peripheral immunity. The morphologic, functional and phenotypic characteristics of LC are becoming well-characterized. However, the mechanisms involved in eliminating LC are poorly understood. In this report, we demonstrated that murine epidermal LC constitutively express the Fas antigen (CD95) and the expression was up-regulated by the addition of IFN-gamma in cultures. Interestingly, epidermal LC underwent apoptosis by the addition of both recombinant soluble Fas ligand (FasL) and IFN-gamma, but not by FasL alone. These results suggest that LC may acquire the susceptibility to Fas-mediated apoptosis through up-regulation of the Fas expression by IFN-gamma derived from activated T cells and that the elimination of LC may be important for preventing excess cutaneous inflammatory diseases.

Animals↗