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Biomedical subjects

H Umezawa

Publications and source records attributed to H Umezawa.

At least 91 records · Page 5Linked to original sources
PubMed1987

Bisucaberin, a new siderophore, sensitizing tumor cells to macrophage-mediated cytolysis. I. Taxonomy of the producing organism, isolation and biological properties.

Alteromonas haloplanktis strain SB-1123 isolated from deep-sea mud produced a new siderophore, bisucaberin. Bisucaberin rendered tumor cells susceptible to cytolysis mediated by murine peritoneal macrophages which were elicited by Proteose peptone and not yet activated by lymphokine. Bisucaberin exerted its sensitizing activity by both the preincubation with tumor cells and the addition to co-culture of macrophages and tumor cells. The activity of bisucaberin was specifically inhibited by ferric ion. Bisucaberin showed direct cytostasis for tumor cells but did not cause cytolysis in the absence of macrophages. Cytostasis by bisucaberin was attributable to the specific inhibition of DNA synthesis in tumor cells.

Antineoplastic Agents↗
PubMed1987

Bisucaberin, a new siderophore, sensitizing tumor cells to macrophage-mediated cytolysis. II. Physico-chemical properties and structure determination.

The structure of bisucaberin, a new siderophore, was determined to be 1,12-dihydroxy-1,6,12,17-tetraazacyclodocosane-2,5,13,16-tetron e by spectroscopic analysis and X-ray crystallographic analysis. The molecule of bisucaberin consists of a cyclic dimer of 1-hydroxy-1,6-diazaundecane-2,5-dione moiety and is closely related to nocardamine, the trimer of the same moiety.

Antineoplastic Agents↗
PubMed1987

Monocyclic beta-lactam antibiotics: synthesis and antibacterial activity of 4-(substituted ethyl)-2-azetidinone-1-sulfonic acid derivatives.

The synthesis and antibacterial activity of sodium (3S,4R)-3-[2-(2-aminothiazol-4-yl)-(Z)-2-(O-substituted oxyimino)acetamido]-2-azetidinone-1-sulfonates having various substituted ethyl groups at the C-4 position are described. Among various substituents explored, the (substituted isothiuronio)ethyl groups were found to have strong antibacterial activity against a variety of Gram-negative bacteria, and moreover, the ethylene isothiuronium derivative exhibited moderate antibacterial activity against Staphylococcus aureus.

Anti-Bacterial Agents↗
PubMed1987

Biosynthesis of napyradiomycins.

Biosynthetic studies on napyradiomycins were carried out based on the incorporation of [2-13C]acetate and [1,2-13C]acetate. The alignment of acetate units suggested that the B and C rings of napyradiomycins are derived from a pentaketide, while ring A and the side chain may be synthesized from mevalonate.

Acetates↗
PubMed1987

The nature of thiol-compounds which trap cuprous ion reductively liberated from bleomycin-Cu(II) in cells.

Bleomycin-Cu(II) [BLM-Cu(II)], which does not cause DNA strand breaks in vitro, exhibits antitumor activity in vivo. The copper in BLM-Cu(II) is reductively removed in vivo, and the liberated Cu(I) is trapped by intracellular thiol-proteins, thus yielding metal-free BLM. The bioactive species of BLM appears to be the iron-complex. For characterization of the thiol-proteins, thiol-compounds such as dithiothreitol (DTT), cysteine, metallothionein (MT) and alcohol dehydrogenase (ADH) were examined for their ability to trap Cu(I) liberated from BLM-Cu(II). BLM-Cu(II) was incubated at 37 degrees C with the thiol-compounds anaerobically for 1 hour followed by aerobic incubation for 10 minutes. Under these conditions DTT converted BLM-Cu(II) to metal-free BLM, but cysteine did not. However, in the presence of MT, cysteine gave metal-free BLM. The Cu(I) liberated from BLM-Cu(II) by cysteine was trapped by MT with accompanying liberation of Zn(II) and Cd(II) from MT. A part of the liberated Zn(II) formed the complex with the metal-free BLM. Metal-free BLM was also formed from BLM-Cu(II) by combined treatment with cysteine and ADH. BLM-Cu(II) was aerobically incubated with cytosol of MT-induced rat liver at 37 degrees C for 1 hour, and the mixture was analyzed with Sephadex G-75 column chromatography. The amount of copper in the MT fraction was increased concomitant with decrease of the Zn(II) and Cd(II). These results suggest that MT, ADH and other thiol-compounds, which have polythiol ligands, act as Cu(I)-trapping agents to yield metal-free BLM in cells.

Alcohol Oxidoreductases↗
PubMed1987

Enhancement of interleukin 1 and interleukin 2 releases by ubenimex.

The effect of ubenimex on the release of interleukin 1 (IL-1) and interleukin 2 (IL-2) from immuno-competent cells was studied. Ubenimex enhanced release of IL-1 from mouse peritoneal macrophages at 1.0 and 100 micrograms/ml in vitro and the release at 1.0 microgram/ml was larger. When ubenimex was administered to mice IL-1-releasing activity of the peritoneal macrophages was enhanced 3 and 5 days after the administration but not enhanced 1 day after the administration. Ubenimex also enhanced IL-2 release from rat spleen cells at 0.1 and 10 micrograms/ml, when concanavalin A (Con A) was added in the IL-2-releasing system. The enhancement was still observed with mouse spleen cells, when serum was further added. Moreover, thymocyte-proliferating activity was attained in the broths which rat spleen cells were incubated with ubenimex from 0.1 to 10 micrograms/ml in the absence and presence of Con A.

Animals↗
PubMed1987

Syntheses of 23-C-alkylidene, and 23-N-containing derivatives of 5-O-mycaminosyltylonolide.

Several derivatives of 5-O-mycaminosyltylonolide substituted at C-23 have been prepared; these are 23-deoxy-23-C-methylene (3), 23-deoxy-23-C-(methoxycarbonylmethylene) (5), 23-deoxy-23-C-(ethoxycarbonylmethylene) (7), and 23-deoxy-23-C-(butoxycarbonylmethylene) (9), 23-deoxy-23-C-[(2E)-3-(ethoxycarbonyl)-2-propenylene] (11), and 23-deoxy-23-(dimethylaminoimino) (13), and 14-de(hydroxymethyl)-14-nitrile (16) derivatives. The key steps in these syntheses are the reactions of 2',4'-di-O-acetyl-3-O-tert-butyldimethylsilyl-23-deoxy-23-oxo-5-O- mycaminosyltylonolide diethyl acetal (1) with several Wittig reagents, 1,1-dimethylhydrazine and hydroxylamine. Antibacterial activities of these compounds are also described.

Anti-Bacterial Agents↗
PubMed1987

Activation of bleomycin-Fe(III) by bleomycin-Cu(II) and cysteine.

When bleomycin (BLM) was incubated with DNA at 37 degrees C for 30 minutes in the presence of BLM-Cu(II) and cysteine, the DNA became more acid-soluble compared with the reaction without BLM-Cu(II). Superoxide dismutase did not suppress this increased DNA chain breakage. This combination of BLM-Cu(II) and cysteine did not enhance BLM-Fe(II)-induced DNA chain breakage, but caused the DNA chain breakage by inactive BLM-Fe(III). Combination of BLM-Fe(III) with BLM-Cu(II) and cysteine also caused production of malondialdehyde-like product from DNA. Anaerobic incubation of DNA with BLM-Fe(III) and BLM-Cu(I) followed by aerobic incubation produced malondialdehyde-like product, but the incubation with CuCl instead of BLM-Cu(I) did not. These results suggest that activation of BLM-Fe(III) by BLM-Cu(II) and cysteine seems to be due to the reduction of BLM-Fe(III) to BLM-Fe(II) by BLM-Cu(I) formed in the reaction of BLM-Cu(II) and cysteine.

Animals↗
PubMed1987

Protective effect of forphenicinol, a low molecular weight immunomodifier, against infection with Pseudomonas aeruginosa in mice and its mechanisms.

The oral administration of forphenicinol increased the survival rate of both normal and immunodepressed mice intraperitoneally or intratracheally infected with clinically isolated strains of Pseudomonas aeruginosa. The therapeutic effect of amikacin on intraperitoneal infection with P. aeruginosa was enhanced by combined use with forphenicinol. Forphenicinol did not enhance the bactericidal activity of polymorphonuclear cells (PMN) towards P. aeruginosa in vitro, but enhanced it in vivo. In vitro study indicated that the macrophages taken from mice treated with forphenicinol or the cultured supernatant of these macrophages enhanced the bactericidal activity of PMN. The protective effect of forphenicinol against P. aeruginosa infection was thus suggested to be due to macrophage activation followed by the enhancement of the bactericidal activity of PMN.

Adjuvants, Immunologic↗
PubMed1987

Antitumor cells found in tumor-bearing mice given ubenimex.

Antitumor effector cells in spleens of tumor-bearing mice given ubenimex were investigated. The administration of ubenimex, starting 7 days after the tumor inoculation, was effective in inhibiting growth of IMC carcinoma. Spleen cells taken from these mice showed a marked suppression of the tumor growth by the WINN assay. The antitumor activity of spleen cells was reduced by treatment to remove T cells or NK cells, whereas spleen cell preparations enriched for T cells showed the strongest antitumor activity. Moreover, NK activity against YAC-1 cells was found in the spleen. These results indicate that the administration of ubenimex to IMC carcinoma-bearing mice generates cytotoxic T cells and NK cells in the spleen. The antitumor effect of ubenimex was not observed in X-ray-irradiated and in anti-asialo GM1 serum-treated mice.

Adjuvants, Immunologic↗
PubMed1987

Enhancement of colony formation of mouse bone marrow cells by ubenimex.

Ubenimex enhanced colony formation of bone marrow cells from CDF1 mice induced by L920 cell supernatant, which shows a macrophage-colony-stimulating activity (M-CSA), and also enhanced the colony formation induced CDF1 mouse spleen cell conditioned medium, which shows a granulocyte and macrophage-colony-stimulating activity. The maximal effect was obtained at 0.01 microgram/ml. But, ubenimex showed no effect on the nature of the colonies induced by each CSA. By preincubation of the bone marrow cells with ubenimex, M-CSA-induced colony-forming and the M-CSA-binding activities of the cells were increased. These results suggest that ubenimex enhances the CSA-induced colony formation of bone marrow progenitor cells of CDF1 mouse by increasing the amount of the CSA-binding to the cells.

Animals↗