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Biomedical subjects

Yasuhiko Ito

Publications and source records attributed to Yasuhiko Ito.

16 recordsLinked to original sources
PubMed2003

The targeted disruption of the CD98 gene results in embryonic lethality.

CD98 is one of the important molecules for development, cell differentiation, cell proliferation, and regulation of cellular function. In this study, CD98 heavy chain (HC) knockout mice were produced and analyzed. Five targeted ES clones were obtained and colony frequency was about 2%. One (clone 113) of the five heterozygous ES cell clones had undergone aberrant recombination at the 5' side. The aberrant recombination happened at the site between second intron and 5' arm. All lines from correctly targeted clones could not transmit the mutated allele to spermatozoa. The mutated allele derived from the aberrant targeted clone was transmitted to the progeny. However, none of the F2 mice was homozygous for the CD98 mutation, indicating that the targeted disruption of the CD98 gene results in embryonic lethality. The point of embryonic lethality is considered to be between 3.5 and 9.5 dps. These findings indicate that CD98 molecules are essential for mouse embryogenesis.

Alleles↗
PubMed2003

The functional interaction between CD98 and CD147 in regulation of virus-induced cell fusion and osteoclast formation.

Membrane fusion is an important event in the functioning of a living organism. Life starts as a sperm fuses with the membrane of an egg, leading to its fertilization. Membrane fusion is also required for myogenesis, osteogenesis and placenta formation. Multinucleated giant cells originating from monocytes-macrophages are associated with granulomatous lesions formed in response to foreign bodies, viruses, and bacteria. The CD4 molecule acts as a receptor for HIV. The major virus envelope glycoprotein, gp120, attaches to CD4 molecules expressed on the host cell surface. After binding to CD4 on the target cells, HIV is internalized via direct, pH-independent fusion of the viral and cell membranes. However, attachment of HIV to CD4 on the target cells is not sufficient for fusion. Interaction of gp160-expressing cells with neighboring cells bearing surface CD4 molecules is also required for syncytium formation. Syncytium formation and subsequent generalized cell fusion have been reported as potentially important mechanisms of virus-induced cytotoxic effects. Some antibodies against CD98/FRP-1 suppressed virus-induced cell fusion and CD98-mediated cell fusion of monocytes, indicating that CD98/FRP-1 molecules are able to regulate cell fusion. In this study, the functional interaction between CD98 and CD147 was investigated. Three kinds (Ab1, 2, and 3) of anti-CD147 and three kinds of anti-CD98 antibodies were used. Ab1 suppressed CD98-mediated cell fusion, but showed no effect on cell aggregation of Cd(+)U2ME-7 cells, U937-2 cells expressing HIV gp160. On the other hand, Ab2 enhanced the CD98-mediated cell fusion. Ab1 showed suppressive effect at early stage and Ab2 showed enhancing effect at later stage. Ab2 and 3 suppressed the spontaneous cell agglutination and cell fusion of Cd(+)JME-2 cells, Jurkat cells expressing HIV gp160. Ab2 suppressed CD98-mediated cell fusion, but showed no effect on cell aggregation of Cd(+)JME-2 cells. Ab2 cancelled suppression of cell fusion induced by suppressive antibody against CD98. Ab2 and 3 also suppressed CD98-mediated cell fusion of monocytes. This study indicates the functional interaction between CD98 and CD147 in the regulation of cell fusion.

Antibodies, Monoclonal↗
PubMed2003

Crystallization and preliminary X-ray analysis of Yersinia pseudotuberculosis-derived mitogen.

Yersinia pseudotuberculosis-derived mitogen (YPM), a superantigen with no amino-acid sequence similarity to other known superantigens, has been crystallized by the sitting-drop vapour-diffusion method. The crystals belong to space group C2, with unit-cell parameters a = 138.67, b = 78.66, c = 32.91 A, beta = 91.97 degrees. A native data set has been collected to a resolution of 1.8 A using synchrotron radiation. Self-rotation function calculations suggest the presence of three molecules in the asymmetric unit, corresponding to a solvent content of 45%.

Bacterial Proteins↗
PubMed2003

Electrolytic synthesis of ammonia in molten salts under atmospheric pressure.

Ammonia was successfully synthesized by using a new electrochemical reaction with high current efficiency at atmospheric pressure and at lower temperatures than the Haber-Bosch process. In this method, nitride ion (N3-), which is produced by the reduction from nitrogen gas at the cathode, is anodically oxidized and reacts with hydrogen to produce ammonia at the anode.

Journal Article↗
PubMed2003

Pinpoint and bulk electrochemical reduction of insulating silicon dioxide to silicon.

Silicon dioxide (SiO(2)) is conventionally reduced to silicon by carbothermal reduction, in which the oxygen is removed by a heterogeneous-homogeneous reaction sequence at approximately 1,700 degrees C. Here we report pinpoint and bulk electrochemical methods for removing oxygen from solid SiO(2) in a molten CaCl(2) electrolyte at 850 degrees C. This approach involves a 'contacting electrode', in which a metal wire supplies electrons to a selected region of the insulating SiO(2). Bulk reduction of SiO(2) is possible by increasing the number of contacting points. The same method was also demonstrated with molten LiCl-KCl-CaCl(2) at 500 degrees C. The novelty and relative simplicity of this method might lead to new processes in silicon semiconductor technology, as well as in high-purity silicon production. The methodology may be applicable to electrochemical processing of a wide variety of insulating materials, provided that the electrolyte dissolves the appropriate constituent ion(s) of the material.

Calcium Chloride↗
PubMed2002

Mixed chimera status of 12 patients with Wiskott-Aldrich syndrome (WAS) after hematopoietic stem cell transplantation: evaluation by flow cytometric analysis of intracellular WAS protein expression.

Wiskott-Aldrich syndrome (WAS) is caused by defects in the WAS protein (WASP) gene on the X chromosome. We previously reported that flow cytometric analysis of intracellular WASP expression (FCM-WASP) was useful in the diagnosis of WAS in patients and carriers. In this study, we applied FCM-WASP to evaluate the mixed chimera (MC) status of 12 WAS patients who underwent hematopoietic stem cell transplantation (HST). After HST, donor- and recipient-derived peripheral blood mononuclear cells (PBMCs) could be distinguished easily with this method, since the donor cells were WASP(bright), whereas the defective recipient cells were WASP(dim). Furthermore, with use of 2-color FCM-WASP, the MC status could be characterized by cell lineage. Six of the 12 patients with WAS were found to have MC status after HST, whereas others had complete chimera status. MC status was observed in every cell lineage examined. However, among PBMCs, recipient cells were most commonly observed in the monocyte population. Finally, to investigate the naive/memory status of donor and recipient T cells in these patients, 3-color FCM-WASP using anti-CD45RA or CD45RO was performed. We found that, in contrast to WASP(bright) T cells, most WASP(dim) T cells remained naive (CD45RA(+)/RO(-)) more than a year after HST. No imbalance in the ratio of naive to memory T cells was observed in WAS patients before HST. We conclude that FCM-WASP is a potentially useful method for clinical follow-up of WAS patients who have undergone HST. Our findings may also have important implications for the role of WASP during hematopoietic development.

Antigens, CD20↗
PubMed2002

Tris(1-ethyl-3-methylimidazolium) hexachlorolanthanate.

In the title complex, (C(6)H(11)N(2))(3)[LaCl(6)], centrosymmetric octahedral hexachlorolanthanate anions are located at the corners and face-centers of the monoclinic unit cell. The ring H atoms of the cations interact with the Cl atoms of the anions via hydrogen bonding, and bifurcation of the hydrogen bonding is observed. Cation-cation interactions via hydrogen bonding between the ring H atoms and pi-electrons of aromatic rings are also observed as in other imidazolium salts.

Journal Article↗
PubMed2002

Recombinant Vpr (rVpr) causes augmentation of HIV-1 p24 Ag level in U1 cells through its ability to induce the secretion of TNF.

We have found that an HIV-1 accessory gene product Vpr enhanced HIV-1 reproduction in U1 cells chiefly by the induction of TNF, a proinflammatory cytokine, which was also known to be an activator of HIV-1 reproduction. We have generated the functional HIV-1 accessory gene product Vpr in bacterial cells. Vpr was generated in an Escherichia coli system (rVpr), purified with antibodies (Ab) to the 16 C-terminal amino acids of Vpr. The purified rVpr of 15 kDa was examined for its ability to upregulate HIV-1 reproduction in U1 cells, which is a reported function of the authentic Vpr. rVpr upregulated HIV-1 reproduction in U1 cells in a dose-dependent manner and induced the secretion of TNF. The upregulation of HIV-1 by rVpr was completely inhibited not only by anti-Vpr antibodies but also by anti-TNF antibody. These findings suggested that Vpr caused an HIV-1 reproduction in U1 cells through the induction of TNF.

Cell Line↗
PubMed2002

Up-regulated expression of a novel gene in activated human peripheral blood mononuclear cells that is a truncated paralog of the human system L-amino acid transporter 1.

INTRODUCTION AND AIMS: The human system L-amino acid transporter1 (hLAT1) is one of the CD98 light chains and its gene has been mapped to chromosome 16q24. Our preliminary findings have indicated that in HeLa S3 cells there are transcripts whose nucleotide sequences are very similar but not identical to that of the amino acid transporter. This study intends to examine whether these novel transcripts have biological significance through elucidating their genetic aspects and expression profiles in human cells. METHODS: The expression levels of the transcripts were quantified by real-time PCR analysis. Chromosomal mapping of the gene was performed by fluorescence in situ hybridization (FISH). RESULTS: Three types of transcripts were identified and their nucleotide sequences were aligned with the chromosome 16p12 clone with high identity. They encoded 180- or 190-amino acid proteins, showing 92-94% of amino acid identity to the amino-terminal region of the hLAT1 (507 amino acids). However, their 3' non-coding sequences did not show homology to the nucleotide sequence of the amino acid transporter. Their genes were mapped to chromosome 16p11.2-p13.1 as low-copy repeats (LCRs). The transcription of one of these genes in peripheral blood mononuclear cells was significantly up-regulated when the cells were stimulated with concanavalin A. CONCLUSION: We have characterized the three truncated paralogs of the hLAT1 gene. It is suggested that the expression of one of these paralogs may play an important role in the activation of peripheral blood mononuclear cells.

Amino Acid Sequence↗
PubMed2002

Human osteosarcoma-derived cell lines produce soluble factor(s) that induces differentiation of blood monocytes to osteoclast-like cells.

When monocytes were cocultured with human osteosarcoma-derived cells (HOS cells), multinucleated giant cell formation of monocytes was induced. Intriguingly, even when a filter was interposed between monocytes and HOS cells, polykaryocytes also appeared. The multinucleated giant cells have characters similar to osteoclast-like cells. These findings indicate that soluble factor(s) secreted from HOS cells play an important role in polykaryocyte formation from monocytes. Twelve cloned cells were established from HSOS-1 cells and their capacities of inducing osteoclasts were investigated. Three cloned cells inducing nos. 4 and 9 had an ability of inducing osteoclasts (multinucleated giant cells, TRAP, calcitonin receptor and c-src mRNAs, osteoresorbing activity), and three cells, including nos. 1 and 5, did not show the ability. HOS cells and the cloned cells expressed several cytokine mRNAs. M-CSF was detected in the culture fluids of HOS cells, which also expressed RANK and RANK/ODF/OPGL mRNAs. Intriguingly, HOS cells secreting a soluble osteoclast inducing factors(s) expressed TNF-alpha converting enzyme mRNA. Furthermore, OCIF/OPG inhibited HOS cell-induced osteoclastogenesis and soluble RANKL could be detected in the culture fluids of HOS cells expressing TACE, suggesting that one of soluble osteoclast-inducing factor(s) is soluble RANKL. When blood monocytes were indirectly cocultured with HSOS-1 cells or cloned no. 9 cells in the presence of OCIF for 14 days, HOS cell-mediated osteoclastogenesis was suppressed, indicating that RANK-RANKL system is involved in the HOS cell-mediated osteoclastogenesis.

Acid Phosphatase↗
PubMed2002

Human leucocyte antigen-Cw-specific cytotoxic T lymphocytes generated from naive cord blood used for cord blood stem cell transplantation.

Human leucocyte antigen (HLA)-Cw-reactive cytotoxic T lymphocytes (CTL) were generated from cord blood (CB) lymphocytes of two cases used for cord blood stem cell transplantation (CBSCT). In both cases, the CTL were cytotoxic against the patient's leukaemic cells, as well as the patient's Epstein-Barr virus (EBV)-lymphoblastoid cell line (EBV-LCL) and phytohaemagglutinin blasts, and the cytotoxicity was blocked by anti-HLA-class I monoclonal antibodies. In the first case, the CTL recognized Cw 3 (Cw 9 and Cw 10)-positive EBV-LCL, while in the second case, the CTL recognized Cw1 and/or Cw7. These cases suggest that CB T cells may be competent enough for generating CTL to induce a graft-versus-leukaemia effect and/or graft-versus-host disease in patients with CBSCT and that the mismatching of Cw antigens between patient and CB may be related to the outcome of CBSCT.

Acute Disease↗
PubMed2002

Overactive bladder--experimental aspects.

Supra-pontine lesions resulting from neurological disorders such as vascular disease, Parkinson's disease, or Alzheimer type senile dementia lead to an increase in bladder activity. This is due in part to the removal at the cortical inhibitory control of the micturition center in the brain stem - i.e. the pontine micturition center (PMC) - and in part to facilitation of excitatory control. These inhibitory or excitatory controls consist of several neurotransmitter systems, including glutamate, dopamine, gamma-aminobutyric acid (GABA), and acetylcholine. Bladder overactivity caused by cerebral infarction is mediated by upregulation of N-methyl-D-aspartate (NMDA) glutamatergic and D2 dopaminergic excitatory mechanisms, and by downregulation of NMDA glutamatergic and Ml muscarinic inhibitory mechanisms in the brain. Bladder overactivity associated with Parkinson's disease is reportedly induced by a loss of input to the D1 dopaminergic receptor. Furthermore, bladder overactivity caused by Alzheimer type dementia is thought to be mediated by downregulation of M1 muscarinic inhibitory mechanisms. Development of bladder overactivity following cerebral infarction is mediated by activation of the NMDA receptor and accompanied by an increase in c-fos, zif268 and COX-2 mRNA expression in the dorsal pontine tegmentum.

Animals↗
PubMed2002

[A case of mesangial proliferative glomerulonephritis with endothelial damage].

We describe a 71-year-old man, who had been treated for hypertension, myocardial infarction and abdominal aortic aneurysm, and was admitted to our hospital because of proteinuria(3.9 g/day at the outpatient clinic and 1.5 g/day at the time of admission) and edema in the extremities. Light microscopic study of the kidney biopsy specimen revealed mesangial proliferative glomerulonephritis and glomerular paralysis. Electron microscopic findings showed endothelial damage, including widening of the subendothelial space and detachment of endothelial cells from the glomerular basement membrane. Deposition of immunoglobulins and complement was not detected by immunofluorescence studies. These pathological findings resemble the findings of thrombotic microangiopathy, but there were no clinical pictures of HUS/TTP. These findings suggest that hypertension, atherosclerosis and circulating turbulence caused by an aortic aneurysm induced severe glomerular endothelial damage leading to mesangial proliferative glomerulonephritis without an immune response.

Aged↗
PubMed2001

Kinetics of connective tissue growth factor expression during experimental proliferative glomerulonephritis.

Connective tissue growth factor (CTGF) is a member of the CCN family of immediate early genes, which are involved in cell proliferation, migration, and matrix production. Recently, CTGF was observed to be strongly upregulated in human proliferative and fibrogenic renal disease. By in situ hybridization and reverse transcriptase-PCR, the expression of CTGF was investigated in experimental proliferative glomerulonephritis induced by injection of anti-Thy-1.1 antibody in the rat. CTGF expression in cultured rat mesangial cells and glomerular visceral epithelial cells (GVEC) was studied in response to transforming growth factor beta (TGF-beta), an essential pathogenetic factor in this model. In normal rat kidneys, only some GVEC expressed CTGF mRNA. In anti-Thy-1.1 nephritis, CTGF mRNA expression was strongly increased in extracapillary and mesangial proliferative lesions and in areas of periglomerular fibrosis. Early glomerular CTGF overexpression in GVEC coincided with a striking upregulation of TGF-beta2 and to a lesser extent of TGF-beta3. Glomerular CTGF mRNA expression was maximal at day 7, in association with increased TGF-beta1 mRNA and protein expression. CTGF mRNA overexpression by parietal epithelial cells preceded the periglomerular appearance of alpha-smooth muscle actin-positive fibroblasts. In cultured mesangial cells, TGF-beta1, -beta2, and -beta3 transiently increased the CTGF/glyceraldehyde phosphate dehydrogenase mRNA ratio up to threefold versus control at 4 h. In GVEC, upregulation of CTGF mRNA by these TGF-beta isoforms was more sustained, being 8- to 16-fold versus control at 24 h. The kinetics of CTGF expression strongly suggest a role in glomerular repair, possibly downstream of TGF-beta, in this model of transient renal injury.

Animals↗
PubMed1999

Mapping of domains on the human parainfluenza virus type 2 nucleocapsid protein (NP) required for NP-phosphoprotein or NP-NP interaction.

The epitopes recognized by 41 monoclonal antibodies directed against the nucleocapsid protein (NP) of human parainfluenza virus type 2 (hPIV-2) were mapped on the primary structure of the hPIV-2 NP protein by testing their reactivities with deletion mutants. By Western immunoblotting using these monoclonal antibodies, the analysis of deletion mutants of the hPIV-2 NP protein was performed to identify the region essential for NP-NP interaction and phosphoprotein (P)-binding sites on the NP protein. The results indicate that the N-terminal 294 aa of the NP protein are all required for NP-NP self-assembly, and that two C-terminal parts of the NP protein are essential for NP-P binding: one region, aa 295-402, is required for binding to the C-terminal part of the P protein and another region, aa 403-494, to the N-terminal part of the P protein.

Animals↗