Biomedical subjects

T Mayumi

Publications and source records attributed to T Mayumi.

At least 55 records · Page 3Linked to original sources

PubMed2000

Preferential activity of wild-type and mutant tumor necrosis factor-alpha against tumor-derived endothelial-like cells.

Tumor-derived endothelial-like cells (tEC) were prepared by culturing human umbilical vein endothelial cells (HUVEC) in the presence of HT1080 human fibrosarcoma-conditioned medium. tEC showed higher permeability and less cell-adhesion activity than normal HUVEC (nEC). Tumor necrosis factor-alpha (TNF) is known to have tumor-vasculature disrupting activity. tEC showed higher cytotoxicity to recombinant human TNF (rhTNF) than nEC, and was not observed using HUVEC cultured with WI38 human diploid cell-conditioned medium as a medium-control. These results demonstrate that tEC acquire physiological properties of tumor-associated vasculature, and may be a useful model system for the study of the mechanisms of TNF antitumor action. The TNF-mutant RGD-V29 (code No. F4614), which has an inserted 4Arg-Gly-Asp sequence and an 29Arg-->Val replacement, was found to induce greater preferential destruction of tEC compared to rhTNF. When the preferential activities were evaluated in terms of 30% cytotoxicity (IC30) ratio (nEC/tEC), the ratio was 460 for RGD-V29 compared to 4.2 for rhTNF. RGD-V29 also exhibited cell-adhesive function and bound preferentially to the p55 TNF-receptor. Both these properties of RGD-V29 contributed to the tEC selective cytotoxicity, indicating that the RGD ligands and selective p55 receptor binding on the cells, although uncharacterized, are involved in tEC targeting. Therefore, the TNF mutant RGD-V29 may show greater selectivity toward tumor vasculature than wild-type TNF.

Binding, Competitive↗

PubMed2000

Effective cancer targeting using an anti-tumor tissue vascular endothelium-specific monoclonal antibody (TES-23).

Immunoconjugate targeting of solid tumors has not been routinely successful because the endo-thelial cells of blood vessels act as a physical barrier against the transport of macromolecules, such as antibodies. In the present study, we attempted to achieve tumor vascular targeting with an anti-tumor tissue endothelium-specific monoclonal antibody (TES-23). TES-23, an IgG1 monoclonal antibody raised against rat KMT-17 fibrosarcoma-derived endothelial cells, was covalently conjugated with neocarzinostatin (NCS) in a previous study. The TES-23-NCS conjugate induced tumor hemorrhagic necrosis, and showed marked anti-tumor effects against rat KMT-17 fibrosarcoma. This result prompted us to investigate whether this approach would be applicable to various other types of solid tumors. One hour after injection of (125)I-labeled TES-23 into BALB / c mice bearing Meth-A fibrosarcoma and Colon 26 adenocarcinoma, the tumor accumulation of TES-23 was greater than that of the control IgG. In the present study, we report the anti-tumor effects of this monoclonal antibody in mice bearing Meth-A fibrosarcoma. Mice treated with the immunoconjugate showed improved survival with no side effects. This result indicates that common antigens may be found in different kinds of tumor endothelial cells, and that TES-23 might recognize these antigens.

Animals↗

PubMed2000

Facile synthesis of a chitosan hybrid of a laminin-related peptide and its antimetastatic effect in mice.

Laminin, a cell adhesion protein, consists of three peptide chains (alpha-1, beta-1 and gamma-1). The beta-1 chain contains a Tyr-Ile-Gly-Ser-Arg (YIGSR) sequence that has been found to inhibit experimental metastasis in mice. We have prepared a hybrid of a water-soluble chitosan and a laminin-related peptide, and have examined its inhibitory effect on experimental metastasis in mice. A laminin-related peptide, acetyl-Tyr-Ile-Gly-Ser-Arg-betaAla-OH (Ac-YIGSRbetaA-OH), was prepared by a solid-phase method. Ac-YIGSRbetaA-OH was then reacted with a water-soluble chitosan. BetaAla is a spacer and was placed to avoid racemization of the Arg residue when the peptide was coupled with chitosan. Although chitosan has amino groups, they did not react with the peptide. Four methods were tried to achieve a coupling reaction, the diphenylphosphoryl azide method, the diisopropylcarbodiimide/1-hydroxybenzotriazole method, the water-soluble carbodiimide (WSC), and the 2-(1H-benzotriazole-1-yl)-1,1,3,3-tetramethyluronium tetrafluoroborate (TBTU) method, but all four methods were unsuccessful. Therefore, a small spacer, tert-butyloxycarbonyl-Gly, was intercalated in chitosan, by the TBTU method, to facilitate its coupling with the peptide. After removal of the protecting group, the Gly-chitosan was coupled with Ac-YIGSRbetaA-OH by the water-soluble carbodiimide method to give Ac-YIGSRbetaAG-chitosan. Conjugation of the peptide with the larger chitosan molecule did not reduce the inhibitory effect of the peptide on experimental metastasis in mice, it actually potentiated the antimetastatic effect, demonstrating that chitosan may be effective as a drug carrier for peptides.

Animals↗

PubMed2000

Growth inhibition of human leukemia HL-60 cells by an antisense phosphodiester oligonucleotide encapsulated into fusogenic liposomes.

We report here the antisense effect of phosphodiester oligodeoxynucleotide (D-ODN) using fusogenic liposomes (FL) as its carrier. FL has envelope proteins of the Sendai virus within its membrane and introduces its contents directly and efficiently into cytosol by means of the virus-cell fusion mechanism. Using antisense (AS) D-ODN 15-mer complementary to the c-myc proto-oncogene mRNA, including the translation initiation codon site, we analyzed the growth of HL-60 cells by [3H]-thymidine uptake. AS-ODNs encapsulated in FL inhibited the growth by about 70% that of the control HL-60 cells at 2.48 microM. In contrast, sense and scramble D-ODNs encapsulated in FL showed no effect of the growth of HL-60 cells at the same concentration. Even at 50 microM, free form D-ODNs did not show any effect. These results suggest that FL is potentially a useful delivery vehicle for oligonucleotide-based therapeutics, and that D-ODN may be a likely candidate for oligodeoxynucleotides when an efficient delivery system is used.

Base Sequence↗

PubMed2000

Different recognition by peroxisome proliferator structures in rat peroxisomal induction: application of sandwich ELISA using monoclonal antibody against rat peroxisomes.

A novel assay for a peroxisomal beta-oxidation enzyme by sandwich ELISA using a monoclonal antibody (RPX-5) against purified rat liver peroxisomes was developed. Immunoblot analysis revealed that RPX-5 recognized a 78 Kd protein, which is a peroxisomal bifunctional enzyme (PBE) in the beta-oxidation pathway. Immunoprecipitation by RPX-5 and the resulting reduction of PBE activity were dependent on RPX-5 concentrations. Sandwich ELISA using RPX-5 could be used to assay PBE in the range of 30 to 2000 ng protein/ml. In rat hepatocyte cultures, the PBE amount by this assay correlated well with PBE activity, with correlation coefficients of 0.965. Studying the mechanisms of peroxisomal induction, patterns of peroxisomal induction were examined by co-treatment of rat hepatocytes with various peroxisome proliferators (PxPs). Treatment with clofibrate and bezafibrate resulted in neither an additive nor synergistic effect on PBE level. On the other hand, co-treatment with either bezafibrate-Wy-14,643 or clofibrate-MEHP(mono(2-ethylhexyl)phthalate) both resulted in an additive effect. From these results, it is suggested that PxPs of the fibrate group may exert their functions via a common process, and non-fibrate PxPs via a different process in hepatocytes. The cognition site for peroxisome proliferators, therefore, might not involve a single site for inducing peroxisomal enzymes.

3-Hydroxyacyl CoA Dehydrogenases↗

PubMed2000

[Targeting therapy using a monoclonal antibody against tumor vascular endothelium].

Recent studies have revealed that the targeting therapy using monoclonal antibody against tumor associated antigens did not have a clinically satisfactory effect due to various physiological characters of tumor. We propose a novel approach targeting tumor vascular endothelium to solve the inefficiency of common tumor missile therapy. In this study, the tissue distribution of anti-tumor vascular endothelium monoclonal antibody (TES-23) produced by immunizing with plasma membrane vesicles obtained from isolated rat tumor-derived endothelial cells (TECs) was assessed in various tumor-bearing animals. Radiolabeled TES-23 dramatically accumulated in KMT-17 fibrosarcoma, a source of isolated TECs after intravenous injection. In Meth-A fibrosarcoma, Colon-26 adenocarcinoma in BALB/c mice and HT-1080 human tumor tissue in nude mice, radioactivities of 125I-TES-23 were also up to fifty times higher than those of control antibody with little distribution to normal tissues. Furthermore, immunostaining of human tissue sections showed specific binding of TES-23 on endothelium in esophagus and colon cancers. These results indicate that tumor vascular endothelial cells express a common antigen in different tumor types of various animal species. In order to clarify the efficacy of TES-23 as a drug carrier, an immunoconjugate, composed of TES-23 and neocarzinostatin, was tested for its antitumor effect in vivo. The immunoconjugate (TES-23-NCS) caused a marked regression of the tumor, KMT-17 in rats and Meth-A in mice. Thus, from a clinical view, TES-23 would be a novel drug carrier because of its high specificity to tumor vascular endothelium and its application to many types of cancer.

Animals↗

PubMed1999

Bioconjugation of laminin-related peptide YIGSR with polyvinyl pyrrolidone increases its antimetastatic effect due to a longer plasma half-life.

Polyvinyl pyrrolidone (PVP) which can be radically synthesized and have a long blood residency was used to modify the laminin-related peptide YIGSR, and its inhibitory effect on experimental lung metastasis of B16-BL6 melanoma cells was examined. The antimetastatic effect of PVP-conjugated YIGSR (PVP-YIGSR) was more than 100-fold greater than that of native YIGSR. When injected intravenously, PVP-YIGSR showed more than a 15-fold longer plasma half-life relative to native YIGSR. In addition, the stability of YIGSR in plasma was increased by conjugation with PVP. These findings suggest that PVP is a useful polymeric modifier for increasing the antimetastatic activity of YIGSR.

Animals↗

PubMed1999

Suppression of solid tumor growth by a monoclonal antibody against tumor vasculature in rats: involvement of intravascular thrombosis and fibrinogenesis.

We have reported that immunization of rat tumor-derived endothelial cells (TEC) isolated from KMT-17 solid tumors results in the generation of several monoclonal antibodies (MAbs). TES-23, one of these MAbs, recognizes a naturally occurring 80-kDa antigen expressed on endothelial cells of tumor blood vessels. To determine whether such MAbs can suppress solid tumor growth in vivo by impairment of endothelial cells in tumors following direct binding, we tested the biodistribution of (125)I-labeled TES-23 in rats bearing KMT-17 solid tumors. We also examined the effect of treatment using unconjugated TES-23 on tumor growth and histo-pathological changes in tumor tissues. Biodistribution studies showed localization of TES-23 into tumor tissues 60 min after intravenous injection. TES-23 suppressed significantly the growth of KMT-17 solid tumors following administration for 5 days. Histo-pathological examination showed that TES-23 caused degeneration, apoptosis and/or necrosis and denudation of endothelial cells in viable tumor areas following local aggregation and adhesion of lymphocytes, with subsequent intravascular thrombus formation by platelets and fibrin. Our results indicate that TES-23, which recognizes TEC, can target endothelial cells of solid tumor vasculature directly, resulting in growth suppression in vivo by reduction of blood flow due to intravascular thrombosis. Our results also suggest that targeting tumor vasculature is a potentially attractive approach for the treatment of solid tumors.

Animals↗

PubMed1999

Positively charged liposome functions as an efficient immunoadjuvant in inducing cell-mediated immune response to soluble proteins.

In order to design an optimized liposome immunoadjuvant for inducing cell-mediated immune response against soluble proteinaceous antigens, we investigated the effect of liposomal surface charge on the immunoadjuvant action. Positively charged liposomes containing soluble antigens functioned as a more potent inducer of antigen-specific cytotoxic T lymphocyte responses and delayed type hypersensitivity response than negatively charged and neutral liposomes containing the same concentrations of antigens. To clarify the reason of the differential immune response, we examined the delivery of soluble proteins by the liposomes into the cytoplasm of macrophages, using fragment A of diphtheria toxin (DTA) as a marker. We found that positively charged liposomes encapsulating DTA are cytotoxic to macrophages, while empty positively charged liposomes, DTA in negatively charged and neutral liposomes are not. Consistent with this, only macrophages pulsed with OVA in positively charged liposomes could significantly stimulate OVA-specific, class I MHC-restricted T cell hybridoma. These results suggest that the positively charged liposomes can deliver proteinaceous antigens efficiently into the cytoplasm of the macrophages/antigen-presenting cells, where the antigens are processed to be presented by class I MHC molecules to induce the cell-mediated immune response. Possible development of the safe and effective vaccine is discussed.

Adjuvants, Immunologic↗

PubMed1999

A novel vaccine delivery system using immunopotentiating fusogenic liposomes.

We previously reported the preparation and characterization of fusogenic liposomes (FLs), which have two highly immunogenic glycoproteins of the Sendai virus on their surface. In this report, we investigated the capacity of FLs to enhance antigen-specific humoral immunity in mice. FLs function as a lymphocyte mitogen with high immunogenicity consistent with viral envelope proteins. Markedly increased levels of anti-ovalbumin (OVA) antibody were detected in serum from mice immunized with OVA encapsulated in FLs compared to sera from mice immunized with free OVA or OVA encapsulated in plain liposomes. An anti-OVA antibody response was not observed in mice immunized with OVA simply mixed with empty FLs. These results indicate that FLs function as a novel immunoadjuvant in inducing antigen-specific antibody production.

Adjuvants, Immunologic↗

PubMed1999

Tumor vascular targeting using a tumor-tissue endothelium-specific monoclonal antibody as an effective strategy for cancer chemotherapy.

In this study, we attempted to develop tumor vascular targeting with a tumor tissue endothelium-specific monoclonal antibody. TES-23, which strongly and selectively recognizes tumor tissue endothelial cells, was chemically conjugated with Neocarzinostatin (NCS), and the anti-tumor effect was examined. The immunoconjugate, TES-23-NCS, showed, through the use of tumor hemorrhagic necrosis, a marked anti-tumor effect on KMT-17 tumors in rats at a dosage of 17 micrograms/kg (NCS equivalent) without any side effects, probably due to specific tumor vascular injury. By contrast, TES-23 alone (107 micrograms/kg), NCS alone (17 micrograms/kg), and Mopc-NCS (Mopc, 107 micrograms/kg; NCS, 17 micrograms/kg), the immunoconjugate of control antibody, did not have any anti-tumor activities. By tissue distribution analysis, TES-23 and TES-23-NCS showed high accumulation in KMT-17 tumors 1 h after intravenous administration. Moreover TES-23 also accumulated in Sarcoma-180 tumors in mice 1 h after intravenous administration. These results suggest that TES-23 may be a candidate for a potential tumor vascular targeting agent that is applicable to a wide variety of tumor types.

Animals↗

PubMed1999

Apoptosis induction via microtubule disassembly by an antitumour compound, pironetin.

We reported previously that pironetin and its derivatives were potent inhibitors of cell cycle progression at the M-phase and showed antitumour activity against a murine tumour cell line, P388 leukaemia, transplanted in mice. In this paper, we investigated the mechanism of action of pironetins in antitumour activity and cell cycle arrest at the M-phase. As reported previously for murine leukaemia P388 cells, pironetin showed antitumour activity in a dose-dependent manner in the human leukaemia cell line HL-60. Since DNA fragmentation was observed in both P388 and HL-60 cells, the antitumour activity of pironetin is thought to be due to the induction of apoptosis. Pironetin also induced the rapid phosphorylation of Bcl-2 before formation of the DNA ladder in HL-60 cells, as seen with several tubulin binders. These results suggest that the antitumour activity of pironetin is due to apoptosis caused by the phosphorylation of Bcl-2, and that pironetin targets the microtubules. Pironetin and demethylpironetin exhibited reversible disruption of the cellular microtubule network in normal rat fibroblast 3Y1 cells. However, epoxypironetin, which contains epoxide instead of the double bond of pironetin, showed only weak activity. Since the concentrations that inhibit cell cycle progression at the M-phase were the same as those for disruption of the microtubule network, it was suggested that the mitotic arrest induced by pironetin was the result of the loss of the mitotic spindle. These compounds also inhibited the microtubule-associated protein-induced and glutamate-induced tubulin assembly in vitro. Pironetin inhibited the binding of [3H]vinblastine, but not that of [3H]colchicine, to tubulin, and the Kd values revealed that the affinity of pironetin for tubulin is stronger than that of vinblastine. These results suggest that pironetins are novel antitumour agents which inhibit microtubule assembly.

Animals↗

PubMed1999

Molecular design of conjugated tumor necrosis factor-alpha: synthesis and characteristics of polyvinyl pyrrolidone modified tumor necrosis factor-alpha.

We conjugated tumor necrosis factor-alpha (TNF-alpha) with the synthetic polymeric modifier polyvinyl pyrrolidone (PVP) to facilitate its clinical use for anti-tumor therapy. TNF-alpha was chemically conjugated with the terminal carboxyl-bearing PVP at one end of its main chain, which was radically polymerized via the formation of an amide bond between the lysine amino groups of TNF-alpha and carboxyl group of PVP. In vitro specific bioactivity of PVP-conjugated TNF-alpha (PVP-TNF-alpha) relative to that of native TNF-alpha gradually decreased with increases in the degree of PVP attachment. In contrast, PVP-TNF-alpha in which 40% of TNF-alpha lysine residues were coupled with PVP (MPVP-TNF-alpha) exhibited the highest anti-tumor activity among the conjugated derivatives examined. MPVP-TNF-alpha had more than 200-fold higher anti-tumor efficacy than native TNF-alpha, and the anti-tumor activity of MPVP- TNF-alpha was more than 5-fold stronger than that MPEG- TNF-alpha which had the highest anti-tumor activity among PEG-conjugated TNF-alphas examined. Additionally, a high dose of native TNF-alpha induced toxic side-effects such as body weight reduction, piloerection and tissue inflammation, while no side effects were observed following i.v. administration of MPVP-TNF-alpha. The plasma half-life of MPVP-TNF-alpha (360 min) was about 80 and 3-fold longer than those of native TNF-alpha (4.6 min) and MPEG-TNF-alpha (122 min), respectively. These results suggested that PVP is a useful polymeric modifier for increasing the anti-tumor activity of PVP.

Animals↗

PubMed1999

Bioconjugation of laminin peptide YIGSR with poly(styrene co-maleic acid) increases its antimetastatic effect on lung metastasis of B16-BL6 melanoma cells.

A comb-shaped polymeric modifier, SMA [poly(styrene comaleic anhydride)], which binds to plasma albumin in blood was used to modify the synthetic cell-adhesive laminin peptide YIGSR, and its inhibitory effect on experimental lung metastasis of B16-BL6 melanoma cells was examined. YIGSR was chemically conjugated with SMA via formation of an amide bond between the N-terminal amino group of YIGSR and the carboxyl anhydride of SMA. The antimetastatic effect of SMA-conjugated YIGSR was approximately 50-fold greater than that of native YIGSR. When injected intravenously, SMA-YIGSR showed a 10-fold longer plasma half-life than native YIGSR in vivo. In addition, SMA-YIGSR had the same binding affinity to plasma albumin as SMA, while native YIGSR did not bind to albumin. These findings suggested that the enhanced antimetastatic effect of SMA-YIGSR may be due to its prolonged plasma half-life by binding to plasma albumin, and that bioconjugation of in vivo unstable peptides with SMA may facilitate their therapeutic use.

Animals↗

PubMed1999

Target-cell specificity of fusogenic liposomes: membrane fusion-mediated macromolecule delivery into human blood mononuclear cells.

Fusogenic liposome, a unique vector prepared by fusing ultraviolet-inactivated Sendai virus and liposome, is known to efficiently deliver content into various animal cells through membrane fusion. In this study, we examined the target-cell specificity of fusogenic liposome (FL)-mediated macromolecule delivery into human blood cells using diphtheria toxin fragment A (DTA) as a probe. Among the peripheral blood mononuclear cells (PBMC), FL was able to deliver its encapsulates into CD14+ monocytes and CD4-/CD8- T-cells, but not into CD19+ B-lymphocytes, CD4+ T-cells or CD8+ T-cells. The susceptibility of human leukemia cell lines to FL was similar to that of PBMC; the order of the reactivity was U937 (monoblastic leukemia)>MOLT4, Jurkat (T-lymphoma)>Daudi, BALL1 (B-lymphoma)>K562 (erythroblastic leukemia). Interestingly, FL showed similar binding activity to all of these leukemia cell lines. These findings indicate that, among blood cells, monocytes, monoblastic leukemia cells, CD4-/CD8- T-cells and T-lymphoma cells are preferable targets for FL-mediated macromolecule delivery. This is the first demonstration of the existence of non-permissive cells against FL. Our results also suggest that some molecules on target-cells other than the binding targets of SV-derived protein may participate in fusion between FL and cells.

Diphtheria Toxin↗

PubMed1999

IL-15 is elevated in the patients of postoperative enterocolitis.

Serum interleukin 15 (IL-15) levels were measured in 77 patients who were consecutively admitted to our intensive care unit. Postoperative enterocolitis occurred in four patients and Methicillin-resistant Staphylococcus aureus (MRSA), but not Clostridium difficile, was identified in the faecal specimens from these patients. The IL-15 levels in the patients with MRSA enterocolitis were significantly elevated compared with those of other MRSA infections without enterocolitis including pneumonia (n=6) and cholangitis (n=1), and other MRSA non-colonized patients (n=66) (21.2+/-5.2 pg/ml vs 4.3+/-0.2, 4.3+/-0.5). Notably, an increase in serum IL-15 was observed just before clinical manifestation of severe diarrhoea. Our findings suggest that IL-15 may be associated in the pathogenesis of postoperative enterocolitis and its serum level may be a severity indicator of the disease.

Adult↗

PubMed1999

Fusion of sendai virus with liposome depends on only F protein, but not HN protein.

Sendai virus is able to fuse with liposomes even without virus receptors. To determine the roles of envelope protein, hemagglutinin-neuraminidase (HN) and fusion (F) protein, in Sendai virus-liposome fusion, we treated the virus with proteases and examined its fusion with liposomes and the conditions of HN and F protein. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and western blotting analysis showed that the virus treated with 150 units/ml of trypsin, which inactivated selectively hemolysis activity, maintained intact HN, F and partially digested F (32 kDa) protein, while virus treated with 15,000 units/ml of trypsin, which inactivated both hemolysis and neuraminidase activity, had only a 15-kDa digested HN protein and completely digested F protein. The former fused with liposomes, but the latter did not. In the virus treated with chymotrypsin, which lost both hemolysis and neuraminidase activity, F protein was intact, while HN protein was degraded to 15 kDa; in this case the virus fused with liposomes. As the virus with 15-kDa HN protein fused with liposomes and that with 20-kDa protein did not, HN protein does not appear to play any role in virus-liposome fusion. The virus that fused with liposomes had intact F protein. We conclude that Sendai virus-liposome fusion is strongly dependent on the presence of intact F protein, but not HN protein.

Blotting, Western↗

PubMed1999

Different reactions of aortic and venular endothelial cell monolayers to histamine on macromolecular permeability: role of cAMP, cytosolic Ca2+ and F-actin.

Endothelial cells assume a central role in the one process that the permeation of microvessels is accelerated in case of inflammation. We studied the effect of histamine on endothelial permeability, [Ca2+]i, cAMP and F-actin, using same origin aortic and venular cultured endothelial monolayers. When HUVEC were treated with histamine (10(-7)-10(-5) M), permeability of FITC-dextran (molecular weight 70,000) and [Ca2+]i were increased, while cAMP content was unchanged, and F-actin content was reduced. When bovine vein-derived endothelial cells were treated with histamine, [Ca2+]i was increased via H1 receptors, but permeability and F-actin content were not altered. When human aorta-derived endothelial cells were, [Ca2+]i was increased via H1 receptors and cAMP content was increased via H2 receptors, while permeability and F-actin content were not changed. When bovine aorta-derived endothelial cells were, cAMP and F-actin content were increased, while permeability was reduced. These findings suggest that endothelial cells derived from different tissues clearly showed the different reactions to histamine, the increase in [Ca2+]i led to the increase in endothelial permeability, while the increase in cAMP levels led to the reduction in permeability, and finally, F-actin regulated endothelial macromolecular permeability.

Actins↗