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Biomedical subjects

H Omura

Publications and source records attributed to H Omura.

At least 19 recordsLinked to original sources
PubMed1989

Partial purification and characterization of immunoglobulin production stimulating factor derived from Namalwa cells.

We screened for immunoglobulin (Ig) production stimulating factor (IPSF) which enhanced Ig production of human-to-human hybridomas in serum-free culture, and found that culture supernatant and lysate of human lymphoblastoid Namalwa cells stimulated proliferation and Ig production of human-to-human hybridoma HB4C5 cells. The IPSF in Namalwa lysate was partially purified with DEAE-Toyopearl 650M, hydroxylapatite and Superose 6HR 10/30 column chromatographies. The partially purified IPSF was a macromolecule of about 500,000 dalton containing 72,000 dalton protein as a major component. The activity was stable at pH 6 to 12, but inactivated partially by heating over 40 degrees C (60% decrease) and completely by trypsin digestion. These results suggest that the IPSF activity is due to its protein and heat-stable components. The Namalwa IPSF stimulated proliferation of human-to-human hybridomas but not that of mouse-to-mouse hybridomas. The IPSF also stimulated Ig production of human-to-human hybridomas derived from NAT-30 cells, but not that of other human-to-human or mouse-to-mouse hybridomas. NAT-30 is a human fusion partner derived from Namalwa cells. These results suggest that the Namalwa IPSF is an autocrine factor that stimulates proliferation and Ig production of hybridomas derived from NAT-30 cells.

Animals↗
PubMed1988

Algal phycocyanins promote growth of human cells in culture.

The growth-promoting substances in a non-dialyzable extract of Synechococcus elongatus var. on RPMI 8226 cells (a human myeloma cell line) were separated by gel filtration and ion exchange chromatography. By gel filtration with Sepharose 4B, the dialyzate was separated into two fractions. One fraction was green-colored (P-1) and the other was blue-colored (P-2). The P-2 fraction had a higher growth-promoting activity than P-1. By ion exchange chromatography, the P-2 fraction was separated into two blue-colored fractions of phycocyanin and allophycocyanin. Both biliproteins promoted the growth of RPMI 8226 cells; however, allophycocyanin was more active than phycocyanin.

Cell Division↗
PubMed1988

Production of human-human hybridomas secreting monoclonal antibodies reactive to breast cancer cell lines.

We produced human-human hybridomas by fusing lymph node lymphocytes of breast cancer patients with a fusion partner, HO-323 cells, in the presence of 50% polyethylene glycol, and screened hybridomas producing monoclonal antibody (MoAb) reactive to a breast cancer cell line, MCF-7. Among 11 hybridomas secreting IgM reactive to MCF-7, four hybridomas (H15A3, H15F2, K15B4, and K15C3) produced IgM reacting specifically to breast cancer cell lines (MCF-7 and HBC-5). Among them, H15A3 proliferated in a serum-free (RDF) medium supplemented with insulin, transferrin, ethanolamine, selenium, and endothelial cell growth supplement, as fast as in 10% FCS-RDF medium. According to transfer blotting analysis, the H15F2 MoAb reacted with a 40,000 dalton antigen in MCF-7 cells.

Antibodies, Monoclonal↗
PubMed1988

Human hybrid immunoglobulin M containing immunoglobulin A.

Some hybridoma clones made by fusion of a human lymphoblastoid cell line, HO323 with human B lymphocytes, secreted not only IgA but also IgM-like immunoglobulin molecules. The IgM-like immunoglobulin had a molecular size of 900 K which corresponded to that of IgM. Immunochemical analyses revealed that the IgM-like immunoglobulin contained two monomeric IgA and three monomeric IgM molecules. In the IgA moieties, half of original light chains were replaced with kappa chains derived from the IgM, and vice versa.

Cell Line↗
PubMed1987

Specificity of anti-polynucleotide monoclonal antibodies from human-human hybridomas.

Nine human-human hybridoma clones, secreting monoclonal antibodies reactive with nucleic acids, were generated by fusing with lymphocytes of lung cancer or systemic lupus erythematosus patients. These hybridoma antibodies were classified into 5 types, in terms of reactivities with DNA, RNA, various synthetic nucleic acids and cardiolipin. Hybridoma clone SU-1 secreted antibody reacting with dsDNA, ssDNA and RNA (type I). Clone HL-321 did not react with these, but with poly (dT), poly (I) and poly (G) (type II). Clone HL-349 was reactive with almost all nucleic acids tested and also with cardiolipin (type III). Clones HF-4, HF-7, HB-7 and HL-259 reacted with ssDNA, poly (A), poly (G) and cardiolipin, but not with RNA (type IV). HB-5 and SH-9 antibodies were reactive only with poly (dT) (type V).

Antibodies, Monoclonal↗
PubMed1986

HO-323, a human B-lymphoblastoid cell line useful for making human-human hybridomas.

A 6-thioguanine-resistant human B-lymphoblastoid cell line, HO-323, was isolated for making human-human hybridomas with high efficiency. Fusions with peripheral blood lymphocytes of systemic lupus erythematosus (SLE) patients and lymphocytes isolated from lymph nodes of lung and breast cancer patients yield constantly more than one hybridoma clones per 10(5) HO-323 cells plated. HO323 cells also fused with lymphocytes from normal peripheral blood to give hybridomas in the same efficiency. The HO-323 cells were diploid with 46 chromosomes and non-secretors of immunoglobulins. This parent cells doubled every 15 hr and could proliferate in serum-containing medium, even if they were plated at low cell density of less than 10(3) cells/ml. The cells could grow in serum-free medium as well as in serum-containing medium, and the resultant human-human hybridomas could also grow in the same media.

B-Lymphocytes↗
PubMed1985

Human-human hybridomas secreting antibodies specific to human lung carcinoma.

Human Namalwa cells were screened in serum-free medium and in 6-thioguanine, then fused with human lymphocytes from lymph nodes of lung adenocarcinoma cancer patients. Extensive testing using 14 lung cancer cell lines, 11 other cancer cell lines and 4 normal fibroblast lines identified monoclonal antibodies produced by 4 hybridoma clones that reacted specifically with lung adenocarcinoma cells. These monoclonal antibodies also reacted with lung adenocarcinoma tissues and not normal tissues or erythrocytes of any blood type. These hybridoma clones grew and stably secreted the antibodies in serum-free medium as well as in serum-containing medium.

Adenocarcinoma↗
PubMed1985

Effect of reductones on cyclic 3', 5'-adenosine monophosphate phosphodiesterase.

The effect of some reductones such as ascorbic acid (AsA), triose reductone (TR), epinephrine (Ep) and their derivatives on cyclic 3', 5'-adenosine monophosphate phosphodiesterase (cAMP PDE) was studied in the presence or absence of Cu2+. AsA, TR, Ep and the reductones related to them inhibited cAMP PDE activity. Among the reductones, TR showed the highest inhibition. AsA, 5-methyl-3,4-dihydroxytetrone, pyrocatechol, p-hydroxyquinone and resorcinol had a relatively high inhibiting activity. The type of inhibition of AsA, TR and Ep was uncompetitive, competitive and noncompetitive, respectively. Cu2+ enhanced the inhibitory action of the reductones markedly and altered the type of inhibition of the reductones.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1983

Formation of mutagens by amino-carbonyl reactions.

The formation of mutagens by amino-carbonyl reactions of 20 kinds of amino acid and sugars after heating at 100 degrees C for 10 h was examined by the Ames test. The browned solutions of Gly, Ala, Val, Leu, Ile, Ser, Thr, Gln, Lys X HCl, Arg, Phe, Cys, Met and Pro with Glc caused mutation of Salmonella typhimurium TA100 and/or TA98 with or without S9 mix. The presence of S9 mix increased the mutagenic activity of the browned solutions of Cys and Phe with Glc on TA100 and of those of Gly, Ala, Val, Ile and Cys on TA98, but decreased the activity of other solutions. No revertants of Salmonella were induced by the browned solutions of Trp, Tyr, Asp, Asn, Glu and (Cys)2 with Glc. Among positive browned solutions, Cys, Lys, Arg and Phe had the stronger activity, but their activity was weak compared with that of pyrolysates or chemical mutagens such as Trp-P-1, Trp-P-2 and 4-nitroquinoline-N-oxide. The mutagenic activity of the browned solutions increased with prolongation of heating time and varied with the pH of the reaction mixture. Fru, Gal, Ara, Xyl, Man, Lac and Suc also had the ability to form mutagens in the browning reactions with amino acids.

Amino Acids↗
PubMed1983

lambda DNA-fragmenting actions of ascorbic acid and triose reductone in the presence of Cu2+.

Lambda DNA-fragmenting actions of ascorbic acid (AsA) and triose reductone (TR) in the presence of Cu2+ were studied. The mixture of AsA or TR and Cu2+ caused a marked fragmentation of lambda DNA (3.2 X 10(7) daltons) within the first 1 min of reaction. Further incubation resulted in accumulation of the most abundant species of fragmented lambda DNA having a molecular weight of 1.3 X 10(5) daltons. The mixture of AsA or TR and Cu2+ fragmented calf thymus DNA to produce the fragmented DNA of which 5'-OH terminal groups have a mixture of free OH groups and phosphodiester linkage. The mixture of AsA or TR and Cu2+ was also found to fragment lambda DNA to produce dCMP predominantly as 5'-OH terminal nucleotides.

Adenosine Triphosphate↗
PubMed1978

Breaking action of reductones related to ascorbic acid on nucleic acids.

The action of two types of ascorbate-related reductones on nucleic acids was investigated by comparison with that of ascorbic acid (AsA). Amino reductone (ScA) and thiol reductone (MHC) caused strandscissions in nucleic acids. This was confirmed by the fact that reductones lowered the viscosity of DNA solution and shifted the peaks of DNA and RNA to the low molecular side in centrifugal profile. Cu2+ strengthened their action as in the case of enediol reductones. The braking activity of thiol reductone is relatively wesk compared with those of amino and enediol reductones. The preferential degradation of spurinic acid was caused with amino and thiol reductones, suggesting that pyrimidine clusters in nucleic acids were susceptible to breakage.

4-Hydroxycoumarins↗
PubMed1976

Effect of reductones on glyoxalase I1.

The effect of some reductones on glyoxalase I prepared from animal and microbial origins has been studied. The enzyme was extracted from ox liver or baker's yeast and partially purified by ammonium sulfate fractionation, gel filtration and ion exchange chromatography. Aliphatic reductones such as ascorbic acid, ascorbic acid 3-phosphate and triose reductone showed strong to medium inhibition, while dehydroascorbic acid showed no inhibition. Kinetic analysis indicated that the inhibition mechanism of ascorbic acid was uncompetitive. Varying extents of inhibition were observed among three kinds of diphenols belonging to aromatic reductones. They were in the order of increasing inhibitory power resorcinol, hydroquinone and catechol for the ox liver enzyme, and catechol, resorcinol and hydroquinone for the yeast enzyme. p-Benzoquinone, an oxidized reductone, exhibited marked inhibition on both enzymes. Its action seemed due to reaction with amino and/or sulfhydryl functions of enzyme protein and those of glutathione, one of the substrates.

Animals↗