Biomedical subjects

Koki Takahashi

Publications and source records attributed to Koki Takahashi.

4 recordsLinked to original sources

PubMed2004

Vaccination with autologous endothelium inhibits angiogenesis and metastasis of colon cancer through autoimmunity.

Overcoming immune tolerance of tumor angiogenesis should be useful for adjuvant therapy of cancer. We hypothesized that vaccination with autologous endothelium would induce an autoimmune response targeting tumor angiogenesis. To test this concept, we immunized BALB/c mice with a vaccine of glutaraldehyde-fixed murine hepatic sinusoidal endothelial cells (HSEs) in a lung metastasis model of Colon-26 cancer. Vaccination with autologous HSEs induced both preventive and therapeutic anti-tumor immunity that significantly inhibited the development of metastases. ELISA revealed an immunoglobulin response involving IgM and IgG subclasses. These antibodies had a strong affinity for antigens of both murine and human endothelium, and lyzed endothelial cells in the CDC assay. Flow-cytometry and chromium-release cytotoxicity assay revealed a specific CTL response against endothelial cells, which were lyzed in an effector: target ratio-dependent manner. Neither antibodies nor CTLs reacted with Colon-26. The effect of autologous HSEs was more pronounced than that of xenogeneic human umbilical vein endothelial cells (HUVECs), which were tested in the same experimental setting. Our results suggest that vaccination with autologous endothelium can overcome peripheral tolerance of self-angiogenic antigens and therefore should be useful for adjuvant immunotherapy of cancer.

Animals↗

PubMed2003

Epigallocatechin gallate, the main component of tea polyphenol, binds to CD4 and interferes with gp120 binding.

BACKGROUND: Epigallocatechin gallate (EGCG), the major component of tea polyphenol, has been reported to have various physiologic modulatory activities. Several reports also have shown that catechin has a protective effect against HIV infection, part of which is mediated by inhibiting virions to bind to the target cell surface. OBJECTIVE: We investigated the effect of EGCG on the expression of CD4 molecules and on its ability to bind gp120, an envelope protein of HIV-1. METHODS: Peripheral blood CD4+ T cells were incubated in the presence of EGCG, and the expression of CD4 was evaluated by means of flow cytometry. The effect of EGCG on the antibody binding to CD4 was investigated by using a sandwich ELISA, and the effect on the gp120 binding to CD4 was analyzed by means of flow cytometry. RESULTS: EGCG efficiently inhibited binding of anti-CD4 antibody to its corresponding antigen. This effect was mediated by the direct binding of EGCG to the CD4 molecule, with consequent inhibition of antibody binding, as well as gp120 binding. CONCLUSION: The present results suggest a potential preventive effect of EGCG on HIV-1 infection by modulating binding to CD4.

Antibodies, Monoclonal↗

PubMed2003

[Computer management to avoid errors in transfusion].

Even with the great progress in blood safety, such as the nucleic acid amplification test(NAT) for HBV, HCV and HIV, ABO-mismatched transfusion still occurs in the 21st century. Computer crossmatch between the patient's blood type already registered on computer, the patient's blood type as examined just before transfusion and the blood type labeled on blood bags all help avoid misunderstanding of blood type at shipping. Computerized management of the transfusion services database is also effective in promoting appropriate transfusion or autologous transfusion. Since mistakes can occur anywhere in the system, the Japanese Society of Blood Transfusion(JSBT) made a poster showing six steps where errors were most likely. They then distributed a questionnaire about mismatched transfusion to 777 major hospitals and made it clear that the main cause of mistakes was confirmation errors at bedside before transfusion. In response to the findings, JSBT created a manual for performing exactly matched and safe transfusions, including a manual for transfusion in emergencies, as well as first-line treatment procedures in case of major mismatched transfusion. In order to avoid mistakes at bedside, a barcode matching system between the patient's wristband and blood bag is ideal. It will also be useful for comprehensive risk management in modern medicine.

Blood Group Incompatibility↗

PubMed2002

Enhanced activities and gene expression of phosphodiesterase types 3 and 4 in pressure-induced congestive heart failure.

Phosphodiesterase (PDE) was shown to be downregulated in the failing hearts of transplant recipients, while it was upregulated in hypertrophied hearts induced by isoproterenol and calsequesterin overexpression. We examined the time course of gene expression and the activity of PDE3 and PDE4 in an animal model of salt-induced hypertension, left ventricular hypertrophy, and congestive heart failure (CHF). Dahl salt-sensitive (DS, n = 25) and salt-resistant rats (DR, n = 25) were fed with an 8% NaCl diet after the age of 6 weeks. At 11 weeks (hypertension and hypertrophy stage in DS), PDE4 activity in the heart was higher in DS than in DR. At 18 weeks (hypertension and CHF stage in DS), both PDE3 and PDE4 activity in both the heart and aorta was approximately twofold higher in DS than in DR. The ratios of PDE3 and PDE4 mRNA to GAPDH mRNA in the heart were both approximately twofold higher in DS than in DR at 11 and 18 weeks. The cardiac cyclic adenosine monophosphate content and plasma nitric oxide concentration were higher in DS than in DR at 11 weeks but both of them were lower in DS than in DR at 18 weeks of age. In this animal model, gene expressions of PDE3 and PDE4 were augmented from the hypertrophic stage. PDE3 and PDE4 activities were subsequently enhanced in the CHF stage and seemed to contribute to the development and exacerbation of CHF.

3',5'-Cyclic-AMP Phosphodiesterases↗