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Koichi Oshima

Publications and source records attributed to Koichi Oshima.

10 recordsLinked to original sources
PubMed2006

Pitavastatin inhibits lysophosphatidic acid-induced proliferation and monocyte chemoattractant protein-1 expression in aortic smooth muscle cells by suppressing Rac-1-mediated reactive oxygen species generation.

Lysophosphatidic acid (LPA), a product generated during oxidative modification of low-density lipoprotein (LDL) and a major lipid extracted from human atherosclerotic plaques, has been shown to elicit smooth muscle cell (SMC) proliferation and inflammation, thereby being involved in atherogenesis. Recently, statins, an inhibitor of 3-hydroxy-methylglutaryl coenzyme A (HMG-CoA) reductase, have been reported to reduce the risk of cardiovascular events and slows the progression of atherosclerosis, at least partly, via pleiotropic effects. However, the effect of statin on the LPA-signaling in SMCs remains to be elucidated. In this study, we investigated whether and how pitavastatin could inhibit the LPA-induced proliferation and monocyte chemoattractant protein-1 (MCP-1) expression in cultured human aortic SMCs. LPA dose-dependently increased intracellular reactive oxygen species (ROS) generation in SMCs, which was blocked by diphenylene iodonium (DPI), an inhibitor of NADPH oxidase or pitavastatin. The anti-oxidative property of pitavastatin was prevented by simultaneous treatment of geranylgeranyl pyrophosphate. Furthermore, overexpression of dominant negative Rac-1 mutant was found to inhibit the LPA-induced ROS generation in SMCs. LPA induced Rac-1 activation in SMCs, which was suppressed by pitavastatin or LPA receptor antagonist. Pitavastatin, DPI, and an anti-oxidant N-acetylcysteine inhibited the LPA-induced proliferation and MCP-1 gene expression in SMCs. These results suggest that pitavastatin could block the LPA-induced proliferation and MCP-1 expression in SMCs by suppressing Rac-1-mediated NADPH oxidase-dependent ROS generation. Our present study provides a novel beneficial aspect of pitavastatin; pitavastatin may act as a blocker of the LPA-signaling in SMCs.

Antioxidants↗
PubMed2006

Regulation of vascular smooth muscle proliferation and migration by beta2-chimaerin, a non-protein kinase C phorbol ester receptor.

The proliferation and migration of vascular smooth muscle cells (SMC) are important aspects of atherogenesis. Activated growth factor signaling in injured vessels subsequently promotes a number of intracellular events resulting in the phenotypic modulation of SMC. Here, we investigated the role of beta2-chimaerin, a non-protein kinase C phorbol ester receptor with Rac-GTPase-activating protein activity, in growth factor-stimulated SMC. The endogenous expression of beta2-chimaerin was detected in cultured human SMC by reverse transcription-polymerase chain reaction and immunohistochemistry. Next, the overexpression of HA-tagged wild-type human beta2-chimaerin was attempted using cultured rat SMC with a recombinant adenovirus (Adv-beta2-Chim). Adv-LZ encoding beta-galactosidase (LacZ) was used as the control. The proliferation of SMC stimulated by platelet-derived growth factor (PDGF-BB, 10 ng/ml), as measured by cell-counting and 5-bromo-2'deoxyuridine incorporation assay, was suppressed by infection with Adv-beta2-Chim (50-200 MOI), but not with control viruses. PDGF-induced SMC migration was inhibited by approximately 25% after infection with Adv-beta2-Chim (200 MOI) using a modified Boyden's chamber assay with a fibronectin-coated membrane. Confocal microscopy revealed that PDGF stimulation altered the sub-cellular localization of beta2-chimaerin. The administration of 12-O-tetradecanoyl phorbol 13-acetate also induced changes in the sub-cellular localization of beta2-chimaerin, which was not affected by a presence of the PKC inhibitor (GF109203X). Finally, PDGF-induced Rac1 activation was found to be inhibited in the Adv-beta2-Chim-infected cells. Thus, we demonstrated that beta2-chimaerin regulates the proliferation and migration of SMC downstream of growth factor signaling pathway via the regulation of Rac1 activity. The signaling mediated by beta2-chimaerin may play a role in the regulation of SMC phenotypes, thereby implicating human atherogenesis.

Animals↗
PubMed2005

Differential expression of cytokines, chemokines and their receptors in follicular lymphoma and reactive follicular hyperplasia: assessment by complementary DNA microarray.

Follicular lymphoma (FL) is pathologically categorised as a low-grade B-cell lymphoma and histopathologically shows follicular proliferation of neoplastic B cells. In the neoplastic follicles of FL, the presence of T cells, macrophages and follicular dendritic cells (FDCs) suggests that these cells may promote a favourable environment for the growth of FL cells. Because FL cells are generally associated with FDCs, FDCs may be considered an important source of cytokines and chemokines. FDCs form the framework for germinal centres and also provide networks for nodules of FL. To evaluate the gene expression in neoplastic follicles of FL and reactive follicles of reactive follicular hyperplasia (RFH), we performed gene expression profiling of FL (n=5) and RFH (n=5) using complementary DNA (cDNA) microarray of cytokines/chemokines and their receptors. FL and RFH exhibited a diffuse down-regulated profile compared with normal peripheral blood cells, which were used as controls, although some genes displayed up-regulated profiles. Hierarchical clustering analysis separated FL and RFH into two distinct groups based on their gene expression profiles. FL cases exhibited significantly higher expression of interleukin 3 receptor alpha (IL-3Ralpha) than RFH. Immunohistochemically, neoplastic follicles of FL frequently expressed IL-3Ralpha, especially in FDCs, but not in FL cells. However, IL-3Ralpha expression was rare or weak in the reactive follicles of RFH. These findings suggest the importance of the micro-environment for FL cell growth. Further studies of cDNA microarray should provide new insight into the molecular pathology of FL and may allow the design of improved therapies.

Adult↗
PubMed2004

A case of a long-time survivor with chronic active Epstein-Barr virus infection.

Epstein-Barr virus (EBV) is associated with hypersensitivity to mosquito bites (HMB) and fatal EBV-associated hemophagocytic syndrome (HPS). The prognosis of patients with chronic active EBV infection (CAEBV) is very poor. We report a rare case of an adult woman patient with a 28-yr history of HMB, who developed EBV-HPS. EBV genome was detected in the serum and peripheral blood lymphocytes. Clonal proliferation of EBV was demonstrated by Southern blot analysis using an EBV genome terminal-repeat probe. This is a very rare case of a long-term survivor with CAEBV. The patient was initially treated with immunochemotherapy and achieved complete remission. However, the patient immediately relapsed and underwent allogeneic bone marrow transplantation (BMT) from her HLA-matched brother. Peripheral blood cell recovered well, and EBV genome disappeared from the peripheral blood. Allogeneic BMT may be effective in eradicating EBV-HPS. Unfortunately, the patient died of graft vs. host disease on the 92nd day after BMT.

Adult↗
PubMed2003

Engraftment and dissemination of T lymphocytes from primary haemophagocytic lymphohistiocytosis in scid mice.

Although primary haemophagocytic lymphohistiocytosis (HLH) is a genetic disorder of T lymphocytes, it remains unclear why T lymphocytes of primary HLH patients preferentially infiltrate the central nervous system and peripheral blood, in addition to the reticuloendothelial systems. We engrafted Herpesvirus saimiri (HVS)-immortalized T-lymphocyte lines established from primary HLH patients into severe combined immunodeficient (scid) mice and examined their capacity to infiltrate mouse organs. A diffuse infiltration of human T lymphocytes was detected in each organ of scid mice treated with 1 x 10(6) T lymphocytes from all four primary HLH patients assessed, whereas no infiltration of T lymphocytes from healthy individuals was observed in any organ. The infiltration of T lymphocytes was mainly observed in the lung, brain and peripheral blood, in association with haemophagocytosis. These cells were positive for HLA-DR, CD3 and either CD8 or CD4, but negative for CD68. Certain markers of proliferation and apoptotic activities were highly positive in these cells. There was no difference between the infiltration pattern of T lymphocytes of primary HLH patients with a perforin deficiency and those without. By Southern blot analysis, T lymphocytes infiltrating mouse organs were observed to be polyclonal. These findings suggest that our murine model implementing HVS-immortalized human T lymphocytes is suitable to clarify the pathogenesis of primary HLH.

Animals↗
PubMed2003

Involvement of the chromosomal translocation t(11;18) in some mucosa-associated lymphoid tissue lymphomas and diffuse large B-cell lymphomas of the ocular adnexa: evidence from multiplex reverse transcriptase-polymerase chain reaction and fluorescence in situ hybridization on using formalin-fixed, paraffin-embedded specimens.

The chromosomal translocation t(11;18) is a unique chromosomal aberration associated with mucosa-associated lymphoid tissue lymphoma. API2 and MALT1 genes have been identified around this translocation. We attempted to find chromosomal abnormalities focusing mainly on the t(11;18) translocation in formalin-fixed, paraffin-embedded tissues of ocular adnexal lymphoproliferative disorders using multiplex reverse transcriptase-polymerase chain reaction and/or two-color interphase fluorescence in situ hybridization. By these methods, the t(11;18) translocation was detected in 1 of 8 patients with reactive lymphoid hyperplasia (13%), 3 of 23 with mucosa-associated lymphoid tissue lymphoma (13%), and 2 of 14 with diffuse large B-cell lymphoma with/without mucosa-associated lymphoid tissue lymphoma (14%). Moreover, we performed fluorescence in situ hybridization analysis to detect any numerical aberration of chromosomes 3, 7, 12, and 18 on some specimens nonselectively. No numerical chromosomal abnormalities were detected in 3 cases of reactive lymphoid hyperplasia, whereas three of four cases of mucosa-associated lymphoid tissue lymphoma and all four cases of diffuse large B-cell lymphoma with/without mucosa-associated lymphoid tissue lymphoma components exhibited one or more abnormalities. These findings indicate a possibility that at least in the ocular adnexa, some diffuse large B-cell lymphomas are derived from mucosa-associated lymphoid tissue lymphomas.

Adult↗
PubMed2002

[CD5+ CD10+ extranodal B-cell lymphoma with tetraploid chromosomal abnormality].

An 84-year-old man was admitted with pleural lymphomatous effusion and bone marrow infiltration. The abnormal cells from the effusion showed abundant basophilic cytoplasm, large atypical nuclei, and small nucleoli with frequent mitosis. The abnormal cells were found to be CD5+, CD10+, CD19+, and CD20+ by flow cytometry, and had clonal rearrangements of the IgH-JH gene, indicating the existence of a clonal B-cell population. No bcl-1, bcl-2, bcl-6, or c-myc rearrangement was found. Neither human herpesvirus 8 (HHV-8) nor Epstein-Barr virus was detected in the abnormal cells. Tetraploid chromosomal abnormality was present. After administration of prednisolone, transient disappearance of the effusion was obtained.

Aged↗
PubMed2002

[Angioimmunoblastic T cell lymphoma (AITL) with autoimmune thrombocytopenia].

We present a case of angioimmunoblastic T cell lymphoma (AITL) with autoimmune thrombocytopenia. A 85-year-old man was admitted to our hospital with thrombocytopenia, generalized lymphadenopathy, pleural effusion, and splenomegaly in June 2000. Blood chemistry revealed hemoglobin and platelet counts of 8.8 g/dL and 26 x 10(9)/L, respectively. The level of platelet-associate-IgG was 2568.9 ng/10(7) cells. The direct Coombs test was positive. The level of serum IL-6 was 10.2 pg/ml. Megakaryocytes in the bone marrow increased. Lymph node biopsy showed diffuse proliferation of atypical lymphoid cells with a clear cytoplasm accompanied by plasma cells and small vessels. He was diagnosed as having AITL with autoimmune thrombocytopenia and hemolytic anemia. He received repeated platelet transfusion, and a limited effect of prednisolone therapy on his platelet count was observed. Combination chemotherapy lessened the extent of the lymphadenopathy and slightly elongated the interval of platelet transfusion. We next performed splenic irradiation and a slight increase in the platelet count was observed. He died of pneumonia in August 2000. Autoimmune thrombocytopenia associated with AITL is rare and the therapy containing prednisolone and chemotherapy is reported to be partly effective. Our case showed a minor response of autoimmune thrombocytopenia to splenic irradiation. Therapeutic intervention for hypersplenism should be considered if thrombocytopenia is not improved by chemotherapy alone.

Aged↗