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Biomedical subjects

K Iwabuchi

Publications and source records attributed to K Iwabuchi.

At least 19 recordsLinked to original sources
PubMed2005

Decrease in the glyceraldehyde derived advanced glycation end products in the sera of patients with Vogt-Koyanagi-Harada disease.

BACKGROUND/AIMS: Advanced glycation end products (AGEs) are considered to act as mediators of both age related pathologies and diabetic complications. It was recently reported that glyceraldehyde derived AGE (AGE-2) has a strong biological effect on various diseases. The aim of this study was to investigate the serum AGE-2 levels in Vogt-Koyanagi-Harada (VKH) disease. METHODS: Sera were obtained from 31 patients with active VKH. 20 of these 31 patients were treated with systemic corticosteroids. As controls, 33 healthy volunteers were also examined. The serum AGE-2 levels were determined with a competitive enzyme linked immunosorbent assay using AGE-2 polyclonal antibody. RESULTS: The mean AGE-2 level in the sera of patients with VKH disease was 4.91 (SD 2.23) U/ml, which was significantly lower than that of the healthy control subjects (8.32 (2.94), p<0.001). The average serum AGE-2 level significantly increased to 13.49 (2.17) U/ml after the patients were treated with systemic corticosteroids (p<0.001). CONCLUSIONS: These results suggest that AGE-2 may be involved in the onset of VKH disease.

Acute Disease↗
PubMed2004

Glucosamine, a naturally occurring amino monosaccharide, suppresses the ADP-mediated platelet activation in humans.

OBJECTIVE: To evaluate the anti-thrombotic action of glucosamine, a naturally occurring amino monosaccharide, platelets were stimulated with ADP in the presence of glucosamine, and its effects on platelet functions were examined. MATERIALS AND METHODS: Human platelet-rich plasma was stimulated with 2.5 microM ADP in the presence of glucosamine (0.01 approximately 1 mM) or other aminosugars (N-acetyl-glucosamine, galactosamine or N-acetyl-galactosamine, 1 mM), and platelet aggregation was monitored. Furthermore, the effects of glucosamine on the thromboxane A2 production, release of granule contents, intracellular calcium mobilization and phosphorylation of Syk (a 72 kD protein tyrosine kinase) were evaluated following ADP-stimulation. In addition, the binding of [3H] ADP to its receptors was examined. RESULTS: Glucosamine (>0.01 mM) dose-dependently suppressed platelet aggregation in response to ADP (p < 0.05), whereas N-acetyl-glucosamine, galactosamine or N-acetyl-galactosamine (1 mM) did not affect the ADP-induced platelet aggregation. Furthermore, glucosamine (>0.1 mM) inhibited the extracellular release of granule contents (ATP and platelet factor 4) and production of thromboxane A2 from ADP-stimulated platelets (p < 0.05). Moreover, glucosamine significantly repressed the intracellular calcium mobilization at >0.1 mM and phosphorylation of Syk at >0.01 mM upon ADP-stimulation (p < 0.05). In addition, glucosamine (>0.1 mM) inhibited the binding of ADP to its receptors (p < 0.05). CONCLUSION: Glucosamine is able to suppress platelet aggregation, release of granule constituents, thromboxane A2 production, calcium mobilization and phosphorylation of Syk possibly via the inhibition of ADP-binding to the receptors. Glucosamine could be expected as a novel anti-platelet agent for thrombotic disorders due to its suppressive actions on platelets.

Adenosine Diphosphate↗
PubMed2004

Immunoregulatory defects of V alpha 24V+ beta 11+ NKT cells in development of Wegener's granulomatosis and relapsing polychondritis.

The frequency of either CD4(-)8(-) (double negative; DN) or CD4(+) V alpha 24(+)V beta 11(+) NKT cells, the expression of CD1d and the binding of CD1d-tetramer loaded with alpha-galactosylceramide (alpha-GalCer) to NKT cells were analysed in peripheral blood mononuclear cells (PBMCs) of patients with Wegener's granulomatosis (WG), relapsing polychondritis (RP) and healthy subjects (HS). DN and CD4(+) V alpha 24(+)V beta 11(+) NKT cells as well as CD1d-alpha-GalCer tetramer-positive NKT cells, were significantly decreased in number in both WG and RP patients compared to those from HS. When cytokine profiles were analysed in these PBMCs upon stimulation with phorbol ester and calcium ionophore, CD4(+) T cells from patients with WG and RP exhibited a Th1 bias, whereas CD4(+) NKT cells from WG patients in remission showed a Th2 bias. These findings suggest that NKT cells (especially CD4(+) NKT cells) play a regulatory role in Th1 autoimmunity in patients with WG and RP. The reduction in NKT cell counts appears to be associated with the low responsiveness to alpha-GalCer. The dysfunction of NKT cells to recognize ligands such as alpha-GalCer may also contribute to the defects observed in NKT cells from WG and RP patients.

Aged↗
PubMed2004

Centrosome hyperamplification and chromosomal damage after exposure to radiation.

OBJECTIVE: In order to elucidate the effects of radiation on centrosome hyperamplification (CH), we examined the centrosome duplication cycle in KK47 bladder cancer cells following irradiation. METHODS: KK47 cells were irradiated with various doses of radiation and were examined for CH immunostaining for gamma-tubulin. RESULTS: Nearly all control cells contained one or two centrosomes, and mitotic cells displayed typical bipolar spindles. The centrosome replication cycle is well regulated in KK47. Twenty-four hours after 5-Gy irradiation, approximately 80% of irradiated cells were arrested in G2 phase, and at 48 h after irradiation, 56.9% of cells contained more than two centrosomes. Laser scanning cytometry performed 48 h after irradiation showed the following two pathways: (1) unequal distribution of chromosomes to daughter cells, or (2) failure to undergo cytokinesis, resulting in polyploidy. With mitotic collection, M-phase cells with CH could be divided into G1 cells with micronuclei and polyploidal cells. Fluorescence in situ hybridization analysis showed clear signs of chromosomal instability (CIN) at 48 h after irradiation. The present study had two major findings: (1) continual duplication of centrosomes occurred in the cell cycle-arrested cells upon irradiation, leading to centrosome amplification; (2) cytokinesis failure was due to aberrant mitotic spindle formation caused by the presence of amplified centrosomes. Abnormal mitosis with amplified centrosomes was detected in the accumulating G2/M population after irradiation, showing that this amplification of centrosomes was not caused by failure to undergo cytokinesis, but rather that abnormal mitosis resulting from amplification of centrosomes leads to cytokinesis block. CONCLUSION: These results suggest that CH is a critical event leading to CIN following exposure to radiation.

Blotting, Western↗
PubMed2003

Primary gastric T-cell lymphoma not associated with human T-lymphotropic virus type I: a case report and review of the literature.

Primary gastric T-cell lymphoma (PGTL) not associated with human T-lymphotropic virus type I (HTLV-I) is extremely rare and such a case is reported herein. The patient was a 58-year-old Japanese male presenting with submucosal tumor of the stomach identified on endoscopic examination. The lesion was diagnosed as non-Hodgkin's lymphoma by endoscopic biopsy and classified as peripheral T-cell lymphoma, unspecified, due to clonal rearrangement of the T-cell receptor beta (TCR) gene and expression of TCR beta protein in the absence of B-cell genotypes and phenotypes. Unlike previously reported cases of HTLV-I-unassociated PGTL, lymphoma in the current case was characterized histologically as "low grade" and phenotypically as CD4+, TIA-1+, granzyme B+, and CD103-. The lymphoma responded well to chemotherapy and radiation, and the patient was well with no detectable disease 10 months after initiation of therapy. A review of patients with PGTL in the literature revealed a few long-term survivors, and the investigation of therapeutic strategies for PGTL is, therefore, necessary.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2003

Short-term and long-term effects of low total pressure on gas exchange rates of spinach.

In this study, spinach plants were grown under atmospheric and low pressure conditions with constant O2 and CO2 partial pressures, and the effects of low total pressure on gas exchange rates were investigated. CO2 assimilation and transpiration rates of spinach grown under atmospheric pressure increased after short-term exposure to low total pressure due to the enhancement of leaf conductance. However, gas exchange rates of plants grown at 25 kPa total pressure were not greater than those grown at atmospheric pressure. Stomatal pore length and width were significantly smaller in leaves grown at low total pressure. This result suggested that gas exchange rates of plants grown under low total pressure were not stimulated even with the enhancement of gas diffusion because the stomatal size and stomatal aperture decreased.

Atmospheric Pressure↗
PubMed2003

Attenuated nuclear shrinkage in neurones with nuclear inclusions of SCA1 brains.

BACKGROUND: Spinocerebellar ataxia type 1 (SCA1) is one of the autosomal dominant neurodegenerative disorders commonly linked to pathological expansion of the CAG repeat of the relevant gene. Nuclear inclusions and neurodegeneration are both triggered by this pathological expansion of the CAG/polyglutamine repeat on ataxin-1, but it remains to be determined whether or not nuclear inclusion formation is associated with accelerated neurodegeneration. OBJECTIVE: To examine the influence of nuclear inclusions on nuclear size and deformity in human brains from patients suffering from SCA1. MATERIAL: Pontine sections of brains obtained at necropsy from seven patients with SCA1 and five controls. METHODS: The size and deformity of each neuronal nucleus was quantified. Nuclei with and without inclusions were examined separately to assess the possible influence of nuclear inclusions on neurodegeneration. RESULTS: Nuclear shrinkage and deformity were more marked in SCA1 brains than in controls. This shrinkage was attenuated in neurones containing nuclear inclusions. CONCLUSIONS: The existence of nuclear inclusions in SCA1 is presumably linked to a mechanism that attenuates rather than accelerates nuclear shrinkage. This in vivo finding may provide a clue to constructing a rational therapeutic strategy for combating neurodegeneration associated with nuclear inclusions.

Adult↗
PubMed2003

VEGF regulates the proliferation of acid-exposed alveolar lining epithelial cells.

BACKGROUND: Acid induced pneumonitis resulting in acute respiratory distress syndrome (ARDS) is characterised by increased alveolar permeability and accumulation of neutrophils. It is hypothesised that vascular endothelial growth factor (VEGF) is involved in the development of lung oedema. Furthermore, lower levels of VEGF are detected in bronchoalveolar lavage fluid from patients with ARDS than from non-ARDS patients. We hypothesised that VEGF acts cytoprotectively and have investigated this possibility in vitro with A549 cells. METHODS: A549 cells were incubated in 24 well culture dishes 24 hours before exposure to acid, then incubated with serum free medium containing various concentrations of HCl for 30 minutes at 37 degrees C in 5% CO(2). The acidified medium was changed to normal complete medium; at specified incubation periods the supernatants were collected and the VEGF concentration measured and the number of adherent cells counted. RESULTS: Proliferation of A549 cells and VEGF production were suppressed for at least 48 hours in HCl at a concentration of 50 mM. Restoration of cellular proliferation occurred following exogenous administration of VEGF (concentration of 1-250 ng/ml) and was inhibited by co-incubation with neutralising anti-VEGF antibody, indicating an interaction between VEGF molecules and A549 cells. Control cells were not influenced by administration of exogenous VEGF or anti-VEGF antibody. Treatment with neutralising anti-VEGF receptor (VEGFR) antibodies against VEGFR-1 and VEGFR-2 suppressed proliferation of acid exposed A549 cells but had no effect on control cells. CONCLUSIONS: Exogenous VEGF interacts with VEGFR-1 and VEGFR-2 on the surface and regulates the proliferation of injured alveolar lining epithelial cells in an autocrine or paracrine fashion.

Antibodies↗
PubMed2002

Prostaglandin E1 protects cultured spinal neurons against the effects of nitric oxide toxicity.

The effects of prostaglandin (PG) E(1) on NO neurotoxicity were examined using rat cultured spinal neurons. Rat cultured spinal neurons exposed to the NO donor, 2,2'-(hydroxynitrosohydrazono) bis-ethanamine (NOC18), showed neurotoxic effects that were accompanied by apoptotic nuclear change, free radical generation, a reduction in glutathione, and mitochondrial dysfunction. PGE(1), at concentrations of 1-100 nM, protected cultured spinal neurons from NO toxicity by reversing the oxidative and pro-apoptotic properties elicited by NOC18 exposure. The administration of PGE(1) increased the intracellular cyclic AMP (cAMP) levels in cultured spinal neurons. In addition, reverse transcriptase-polymerase chain reaction (RT-PCR) analysis confirmed the existence of EP4, a cAMP-elevating PGE receptor, in cultured spinal neurons. The protective effects of PGE(1) against NO neurotoxicity was partially blocked by an inhibitor of MEK [the mitogen-activated protein kinase (MAPK)/extracellular-signal-regulated kinase (ERK) kinase], suggesting that the MAPK/ERK pathway may play a significant role in the activity of PGE(1). PGE(1) up-regulated the expression of the anti-apoptotic protein, Bcl-2, as determined by Western blot analysis. PGE(1) also induced the expression of thioredoxin in cultured spinal neurons. Our data indicate that PGE(1) exerts a protective action against NO neurotoxicity in cultured spinal neurons, and suggests a therapeutic potential of PGE(1) against spinal cord disease, such as amyotrophic lateral sclerosis.

Alprostadil↗
PubMed2002

Paradoxical absence of nuclear inclusion in cerebellar Purkinje cells of hereditary ataxias linked to CAG expansion.

Degeneration of cerebellar cortex is one of the principal features of hereditary ataxias linked to expansion of CAG repeat. In an attempt to clarify possible correlation between neuronal depletion and neuronal intranuclear inclusions, both triggered by the pathological expansion of CAG repeat, cerebellar sections from SCA1, SCA2, SCA3, and DRPLA cases were immunostained with anti-ubiquitin or anti-expanded polyglutamine antibody (1C2) and were screened for the presence of neuronal intranuclear inclusions. Although the degree of cerebellar degeneration varied greatly, cerebellar Purkinje cells were uniformly characterised by the absence of neuronal intranuclear inclusion. Complete absence of neuronal intranuclear inclusion in Purkinje cells is apparently paradoxical and hardly explained if neuronal intranuclear inclusion formation is positively correlated to a mechanism accelerating neuronal death. It may, otherwise, suggest an intrinsic link between neuronal intranuclear inclusion formation and neurodegeneration in opposite directions in human Purkinje cells, more or less affected in these CAG repeat disorders.

Antibodies, Anti-Idiotypic↗
PubMed2001

Negative regulation of LPS-stimulated expression of inducible nitric oxide synthase by AP-1 in macrophage cell line J774A.1.

The level of NOS II mRNA was markedly increased during 24 h lipopolysaccharide (LPS) stimulation, but showed no further increase thereafter. On the other hand, the level of NOS II mRNA in J774A.1 cells transfected with an expression vector containing the rat csk cDNA (J.Csk) was significantly increased during 3 h LPS stimulation, but rather decreased thereafter. Although no significant difference was observed in the activation of NF-kappaB by LPS among parental J774A.1, J774A.1 transfected with promoterless vector (J.pBK), and J.Csk cells, activity of c-Jun N-terminal kinase (JNK) and nuclear translocation of nuclear factor activator protein-1 (AP-1) were markedly upregulated in the J.Csk cells. Then luciferase reporter vectors containing NOS II promoter with mutations in two AP-1-like sites (U site, -1126 approximately -1120; L site, -524 approximately -518) were transiently transfected in J774A.1 cells. The promoter activity following LPS stimulation for 24 h was significantly increased by mutation at the L site, but not by mutation at the U site, suggesting that NOS II expression is negatively regulated, at least in part, through the AP-1-like L site in response to LPS.

Animals↗
PubMed2001

Developmental and functional analyses of CD8(+) NK1.1(+) T cells in class-I-restricted TCR transgenic mice.

Using a class-I-restricted T cell receptor (TCR) transgenic mice (Tgm), 2C (Valpha3.1/Vbeta 8.2, specific for L(d) + LSPFPFDL), the development and cytokine production of tg-TCR(+) NKT cells were analyzed. We found that CD8(+) or double negative (DN) NKT cells constituted a major population of NKT cells in the H-2(b/b) 2C Tgm (positive selecting background) or the H-2(b/d) 2C Tgm (negative selecting background), respectively. Virtually no NKT cells were generated in the H-2(k/k) 2C Tgm (neutral selecting background). CD8(+) NKT cells in the H-2(b/b) 2C Tgm expressed CD8alphabeta heterodimers, whereas those in the H-2(b/d) 2C Tgm expressed CD8alphaalpha homodimers. These findings suggest that development of a subpopulation of NKT cells is influenced by the H-2 molecules. Upon stimulation with anti-CD3 mAb, tg-TCR(+) NKT cells generated in the H-2(b/b) and H-2(b/d) backgrounds produced IFN-gamma, but not IL-4.

Animals↗
PubMed2001

Activation and apoptosis of murine peritoneal macrophages by acute cold stress.

Effects of acute cold stress (5 degrees C for 24 h) on the functions of peritoneal macrophages and the mechanisms for controlling host homeostasis were investigated in mice. Phagocytic activity and expression of the cell surface adhesion molecule CD11b/CD18 were markedly increased in peritoneal exudate cells by acute cold stress. These alterations were attributable to an increased number and phenotypical changes of adherent cells from acute cold-stressed mice. On the other hand, a lipopolysaccharide-induced activity of src-family tyrosine kinase Fgr, an expression of interleukin-1beta (IL-1 beta) mRNA, and a bioactivity of IL-1 in the culture supernatants of adherent cells from acute cold-stressed mice were markedly lower than those from control mice. A time course study revealed that the number of adherent cells in peritoneal exudate cells was markedly increased in mice exposed to cold for 24 h but returned to normal numbers when mice were exposed to cold for 72 h. DNA fragmentation and Annexin-V(+) cells were observed in peritoneal exudate cells from acute-cold stressed mice. Thus, cold stress activated macrophages but these macrophages were destined to be eliminated by apoptosis.

Animals↗
PubMed2001

Amelioration of experimental autoimmune encephalomyelitis in C57BL/6 mice by an agonist of peroxisome proliferator-activated receptor-gamma.

Peroxisome proliferator-activated receptor-gamma (PPAR-gamma), a member of the nuclear hormone receptor superfamily, plays a critical role in adipocyte differentiation and glucose homeostasis. It has been implicated that PPAR-gamma functions as a regulator of cellular proliferation and inflammatory responses. In the present study, we examined whether troglitazone, a selective PPAR-gamma agonists, ameliorated experimental autoimmune encephalomyelitis (EAE) induced by administration of myelin oligodendrocyte glycoprotein (MOG) peptide 35-55 in C57BL/6 mice. We found that troglitazone attenuated the inflammation and decreased the clinical symptoms. It was suggested that the amelioration was attributed to the attenuation of pro-inflammatory cytokine gene expressions.

Animals↗
PubMed2001

Tumor suppressor p53 binding protein 1 (53BP1) is involved in DNA damage-signaling pathways.

The tumor suppressor p53 binding protein 1 (53BP1) binds to the DNA-binding domain of p53 and enhances p53-mediated transcriptional activation. 53BP1 contains two breast cancer susceptibility gene 1 COOH terminus (BRCT) motifs, which are present in several proteins involved in DNA repair and/or DNA damage-signaling pathways. Thus, we investigated the potential role of 53BP1 in DNA damage-signaling pathways. Here, we report that 53BP1 becomes hyperphosphorylated and forms discrete nuclear foci in response to DNA damage. These foci colocalize at all time points with phosphorylated H2AX (gamma-H2AX), which has been previously demonstrated to localize at sites of DNA strand breaks. 53BP1 foci formation is not restricted to gamma-radiation but is also detected in response to UV radiation as well as hydroxyurea, camptothecin, etoposide, and methylmethanesulfonate treatment. Several observations suggest that 53BP1 is regulated by ataxia telangiectasia mutated (ATM) after DNA damage. First, ATM-deficient cells show no 53BP1 hyperphosphorylation and reduced 53BP1 foci formation in response to gamma-radiation compared with cells expressing wild-type ATM. Second, wortmannin treatment strongly inhibits gamma-radiation-induced hyperphosphorylation and foci formation of 53BP1. Third, 53BP1 is readily phosphorylated by ATM in vitro. Taken together, these results suggest that 53BP1 is an ATM substrate that is involved early in the DNA damage-signaling pathways in mammalian cells.

Ataxia Telangiectasia Mutated Proteins↗
PubMed2001

Defective development of NK1.1+ T-cell antigen receptor alphabeta+ cells in zeta-associated protein 70 null mice with an accumulation of NK1.1+ CD3- NK-like cells in the thymus.

Development of natural killer 1.1+ (NK1.1+) CD3+ (NK1.1+ T) cells was analyzed in zeta-associated protein 70 (ZAP-70) null ((-/-)) mice. Both NK1.1+ TCRalphabeta+ and NK1.1+ TCRgammadelta+ cell populations were absent in the thymus and spleen. By contrast, the number of NK1.1+ CD3- cells was increased in these tissues. The NK1.1+ CD3- thymocytes in ZAP-70(-/-) mice had surface phenotypes in common with NK or NK1.1+ T cells. However, some of them were discordant either with NK cells or with NK1.1+ T cells. The NK1.1+ CD3- cells produced interferon-gamma upon stimulation with NK1.1 cross-linking in the presence of interleukin-2 and exhibited a substantial cytotoxicity against YAC-1 cells. Moreover, the generation of NK1.1+ T cells with invariant Valpha14Jalpha281 chains was induced from the NK1.1+ CD3- thymocytes following stimulation with phorbol myristate acetate and ionomycin in a neonatal thymic organ culture. An introduction of TCRalpha and beta transgenes to the ZAP-70(-/-) mice resulted in generation of an NK1.1+ TCRalphabeta(dim) population, whereas no substantial CD4+ CD8- or CD4- CD8+ population that expressed the introduced TCRalphabeta was generated in the mainstream T lineage. These findings demonstrate that ZAP-70 kinase is indispensable for the development of NK1.1+ T cells and that the unique NK1.1+ CD3- thymocytes in ZAP-70(-/-) mice contain immediate precursors of NK1.1+ T cells.

Animals↗