Search PubMed⌕ Search

Biomedical subjects

T Osawa

Publications and source records attributed to T Osawa.

At least 415 records · Page 23Linked to original sources
PubMed1980

Analytic study of epileptic absence seizures and effect of sodium valproate treatment.

Two hundred and seventy eight absence seizures were recorded from 60 patients by an intensive monitoring device. They were divided into two subtypes, typical and atypical absences based on their ictal discharges whether the spike-wave rhythm was at 3 cps or not. These two absence seizures did not differ so much with regard to loss of consciousness except that: 1) the durations of discharge in atypical absences were longer than those of typical ones, 2) the recovery from clouded consciousness to a state of full-awareness was apparently delayed in atypical absences after the termination of epileptic discharges, 3) the oral automatisms were more associated with typical absences and the decreased postural tones with atypical absences. By a numerical analysis of two parameters of spike-wave, that is, its frequency ad rhythmicity, it was shown that absences with spike-waves slower than 30 cps and with poor rhythmicity which roughly corresponded with atypical absences were more therapy-resistant in comparison with those having 3 cps spike waves and good rhythm which were usually typical absences. Sodium valproate was more effective on typical absences, however, there was no difference between typical and atypical absences in the therapeutic maintenance concentrations of serum valproate acid. We would like to emphasize that the comparison of the symptomatology between typical and atypical absences is of significance not only for understanding the etiology of the epilepsies but for the guideline of practical pharmacotherapy.

Electroencephalography↗
PubMed1980

Age-dependent changes of the levels of suppressor and helper T cells in New Zealand black mice.

Peanut agglutinin-positive (PNA+) T cells in concanavalin A (Con A) activated spleen cells were found to markedly decrease with age in New Zealand black (NZB) mice but not in non-autoimmune strains, using a fluorescence activated cell sorter (FACS II). On the other hand Limulus polyphemus agglutinin positive (LPA+) T cells in Lens culinaris agglutinin (LcA) activated spleen cells were found to gradually decrease both in NZB and non-autoimmune strains. Since PNA has previously been shown to selectively label Con A-induced suppressor T cells, these results support the previous observation by other investigators that suppressor T cell function declines with age in NZB mice. It was also demonstrated that the level of one of natural thymocytotoxic autoantibodies (NTA-2) developed in NZB mouse serum, which had been shown to have a similar carbohydrate binding specificity to PNA and to exert a cytotoxic effect specifically against suppressor T cells, was elevated early in the life of NZB mice. These results suggest a possible role of NTA-2 in the decline of PNA+-T cells in vivo.

Agglutinins↗
PubMed1980

Characterization of lectin-induced cellular cytotoxicity mediated by mouse spleen cells and the role of lymphotoxin.

The cellular cytotoxicity mediated by mouse spleen cells in the presence of mitogenic or non-mitogenic lectins was established under serum-free conditions and characterized. Compared with the lectin-induced cellular cytotoxicity (LICC) in the guinea-pig, the activity of lymphotoxin (LT) released into the murine LICC assay cultures was very low. However, a positive correlation was found between the strength of LICC and the LT activity released into the supernatants. Moreover, the addition of puromycin, a potent enhancing reagent of guinea-pig LT activity, markedly promoted the LICC when added 4 h after the initiation of the LICC culture. These data, taken together, suggest that LT acts as an effector molecule in the murine LICC systems as well as in the guinea-pig LICC systems. Properties of the effector cell populations mediating LICC were investigated by depletion of plastic-adherent or nylon-wool adherent cells, by treatment of spleen cells with anti-T-cell sera and complement, and by use of nude mouse spleen cells. The results obtained suggest that both concanavalin A and phytohaemagglutinin-P can induce nylon-wool non-adherent T-cell mediated LICC, phytohaemagglutinin-W was found to be capable of inducing both the nylon-wool non-adherent T-cell mediated LICC and the nylon-wool adherent non-T-cell mediated LICC, the major effector of Bauhinia purpurea agglutinin-LICC was found to be the nylon-adherent non-T-cell population.

Animals↗
PubMed1980

Preparation of antibody (IgG)-ricin A-chain conjugate and its biologic activity.

As a model experiment for the preparation of cancer chemotherapeutic agents, a disulfide-linked conjugate of rabbit anti-mouse IgG (RaMIgG) and ricin A-cahin was synthesized. Activated sulfhydryl groups were first introduced into RaMIgG and then the modified RaMIgG was reacted with ricin A-chain. The fraction containing the conjugate was obtained from the reaction mixture by gel filtration through Sephadex G-150 and was characterized by sodium dodecyl sulfate-polyacrylamide disc gel electrophoresis and double immunodiffusion in agar. The inhibitory activity of A-chain against protein synthesis in a cell-free system and the binding activity of RaMIgG to mouse B lymphocytes were both fully retained. The purified conjugate selectively inhibited protein synthesis in mouse B lymphocytes possessing cell surface Ig, but not that in thymocytes. The cytotoxicity was inhibited by adding mouse IgG and an excess amount of RaMIgG to the cell culture. The effects of unlinked RaMIgG and A-chain on the cytotoxicity were negligible even when the two were used as a mixture.

Animals↗
PubMed1980

Induction and separation of mouse helper T cells by lectins.

The capability of Lens culinaris agglutinin (LcA) to induce selectively the helper T cell activity affecting primary antibody response was demonstrated. In the presence of mouse spleen cells, activated with LcA at a concentration of 12 . 5 microgram/ml, optimal augmentation of the humoral immune response to sheep erythrocytes (SRBC) was observed. It was also demonstrated that Limulus polyphemus agglutinin (LPA), which was shown to possess carbohydrate-binding specificity directed to sialic acid residues, preferentially agglutinated helper T cells. Conversely, peanut agglutinin (PNA), which binds preferentially to the sugar sequence beta-D-Gal-(1 leads to 3)-D-GalNAc, did not agglutinate the helper cells. Furthermore, the stimulatory effect of LPA-agglutinated cells on the antibody response was abolished by treatment of the cells with anti-Thy-1 . 2 and complement. These results suggested that the helper cells induced by LcA were T cells and that they have abundant sialic acid residues exposed on the cell surface.

Animals↗
PubMed1980

Characterization of mouse helper and suppressor T cell subsets separated by lectins.

Concanavalin A (Con A)-activated cells were fractionated by separating cells that agglutinate with peanut agglutinin (PNA) which binds preferentially to the sugar sequence beta-D-Gal-(1 leads to 3)-D-GalNAc. PNA-agglutinable cells were found to exert a significant suppressor effect on the primary antibody response to sheep red blood cells, whereas PNA-nonagglutinable cells did not affect the antibody response. It was also found that PNA-agglutinable suppressor cells were sensitive to treatment with anti-Thy 1.2 and complement (C), anti-I-J antiserum and complement, and anti-Ly 2.2 antiserum and complement. These results suggest that the PNA-agglutinable suppressor cells, separated from Con A-activated cells, were T cells and that these suppressor T cells possess abundant beta-galactosyl residues exposed on the cell surface, not masked by sialyl residues. Furthermore, it was found that antigen-specific suppressor cells were also separable by use of the agglutinability with PNA. The PNA-agglutinable suppressor T cell activity was eliminated by treatment of the Con A-activated PNA-agglutinable cells with anti-asialo GM1 and complement, anti-Forssman antiserum and complement, and anti-globoside antiserum and complement, but not by treatment with anti-GM1 antiserum and complement. Conversely, the helper T cell activity that was induced by Lens culinalis agglutinin and separated by Limulus polyphemus agglutinin, was eliminated by treatment of the cells with anti-GM1 and complement, but not by the treatment with the other anti-glycolipid antisera and complement.

Animals↗
PubMed1980

Purification and characterization of a mouse serum glycoprotein increased in level by administration of an antitumor polysaccharide, lentinan.

One of the three kinds of mouse serum proteins increased in level by the administration of lentinan, designated LA, was found to be ceruloplasmin (p-diphenol:O2:oxidoreductase; EC 1.14.18.1) which contains copper atoms and has amine oxidase activity. This mouse ceruloplasmin is a glycoprotein with a molecular weight of approximately 135,000, and its chemical composition is very similar to that of human ceruloplasmin.

Amino Acids↗
PubMed1980

Enhancement of macrophage tumoricidal activity by a serum glycoprotein that increased in OK-432-treated mice.

An antitumor protein that increased in the serum of OK-432-treated mice showed an enhancing effect on the tumor cell killing by OK-432-elicited macrophages as measured by the 51Cr release test. This protein, designated as LB, also enhanced the cytolytic effect of macrophages on normal target cells, although the activity was lower toward normal cells than tumor cells. On the other hand, LB exhibited no effect on normal, thioglycolate-elicited, or heat-inactivated OK-432-elicited macrophages. The effect of LB on the binding of tumor cells to macrophage monolayers was also examined. On the addition of LB, OK-432-elicited macrophages became capable of binding more tumor cells than before. As in the cytolytic assay, the increased binding by the macrophages was not selective for tumor cells, and normal macrophages did not increase the binding of tumor cells upon the addition of LB. These results indicate that LB enhances macrophage-mediated cytotoxicity by increasing intimate binding between the OK-432-elicited macrophages and their target cells.

Animals↗
PubMed1979

Syntheses of O-beta-D-galactopyranosyl-(1 leads to 3)-0-(2-acetamido-2-deoxy-alpha(and -beta)-D-galactopyranosyl)-N-tosyl-L-serine and their interaction with D-galactose-binding lectins.

In order to use, as hapten inhibitors against various galactose-binding lectins, the derivatives of O-beta-D-galactopyranosyl-(1 leads to 3)-O-(2-acetamido-2-deoxy-alpha-D-galactopyranosyl)-L-serine, which is the common core structure of sugar chains of most mucins, the synthesis of these compounds was investigated. Koenigs-Knorr condensation of the 4,6-O-benzylidene derivative of O-(2-acetamido-2-deoxy-alpha-D-galactopyranosyl)-N-tosyl-L-serine methyl ester with 2,3,4,6-tetra-O-acetyl-alpha-D-galactopyranosyl bromide gave O-(2,3,4,L-tetra-O-acetyl-beta-D-galactopyranosyl)-(1 leads to 3)-O-(2-acetamido-4,6-O-benzylidene-2-deoxy-alpha-D-galactopyranosyl)-N-tosyl-L-serine. Deacetylation, followed by acid hydrolysis of the benzylidene group, gave O-beta-D-galactopyranosyl-(1 leads to 3)-O-2-acetamido-2-deoxy-alpha-D-galactopyranosyl)-N-tosyl-L-serine. A beta anomer at the glycoside linkage of the 2-acetamido-2-deoxy-D-galactose residue was also synthesized by the same procedure. Agaricus bisporus (mushroom) hemagglutinin was found to recognize the O-alpha-glycosyl linkage between 2-acetamido-2-deoxy-D-galactose and L-serine, in addition to the O-beta-D-galactopyranosyl-(1 leads to 3)-(2-acetamido-2-deoxy-D-galactose sugar sequence, for which Arachis hypogaea (peanut) and Bauhinia purpurea hemagglutinins were found to be specific. Ricinus communis hemagglutinin is more specific for the O-beta-D-galactopyranosyl-(1 leads to 4)-2-acetamido-2-deoxy-D-glucose (commonly found in serum glycoproteins) than for the O-beta-D-galactopyranosyl-(1 linked to 3)-2-acetamido-2-deoxy-D-galactose sequence. With Wistaria floribunda hemagglutinin, not much difference in the inhibitory activities of these two sugar sequences was observed, and O-(2-acetamido-2-deoxy-alpha-D-galactopyranosyl)-N-tosyl-L-serine was the strongest inhibitor against this lectin.

Antigen-Antibody Reactions↗
PubMed1979

The association between major sialoglycoprotein and spectrin of human erythrocyte membranes as detected by fluorescence resonance energy transfer.

The interactions among the major sialoglycoprotein and peripheral proteins of human erythrocyte membranes were investigated by the long range resonance energy transfer between different fluorescent moieties separately conjugated to proteins. Consequently, direct association between the major sialoglycoprotein and spectrin was observed and divalent cations were required for their association.

Energy Transfer↗
PubMed1979

Concanavalin A-induced increase in the membrane fluidity of chicken erythrocytes.

To determine the fluidity of the membrane lipid phase, chicken erythrocytes were labeled with a stearic acid derivative spin label. When chicken erythrocytes were treated with concanavalin A (Con A), ESR spectra showed a change in the peaks of the labels in membrane lipids, indicating an increase of membrane fluidity. The degree of the increase in fluidity of the membrane lipid phase depended on the valency of the lectin used. Tetravalent Con A induced an increase of membrane fluidity at a concentration as low as 30 micrograms/ml, while a monovalent derivative of Con A did not affect membrane fluidity. This increase in membrane fluidity was observed within 10 min after the addition of Con A. If bound Con A was removed with methyl alpha-D-mannoside later than 60 min after its addition, a complete return of the fluidity to the normal level could not be observed. However, no change was found in the composition of phospholipids or in the fatty acid compositions of phosphatidylcholine and phosphatidylethanolamine of chicken erythrocytes after the addition of Con A, indicating that this increase in membrane fluidity is not caused by a change of lipid composition. The clustering of membrane receptors of chicken erythrocytes for Con A was demonstrated when the two-dimensional distribution of ferritin-conjugated Con A on the membranes was assayed by transmission electron microscopy. Furthermore, it was shown that major receptors for Con A of chicken erythrocytes were transmembrane glycoproteins having apparent molecular weights of 100K, 45, and 33K.

Animals↗
PubMed1979

Binding of bacterial lipopolysaccharide to histocompatibility-2-complex proteins of mouse lymphocytes.

The membrane binding sites for lipopolysaccharide (LPS) were isolated by affinity chromatography of the solubilized membranes prepared from 125I-labeled mouse B-cells and T-cells on an affinity adsorbent prepared by coupling Salmonella minnesota R595 LPS to activated Sepharose 4B. The membrane proteins bound to the affinity adsorbent and eluted with 1.0% Triton X-100 were analyzed according to their mobility on polyacrylamide gel electrophoresis in sodium dodecylsulphate. These membrane proteins were further identified by immunoprecipitation with specific antisera. Immunoglobulins, possibly immunoglobulins M and D, were identified in the eluate from the B-cell membranes. The histocompatibility-2-complex proteins (H-2D, H-2K and Ia antigens) were also found to be binding sites for LPS on both B-cells and T-cells.

Animals↗
PubMed1979

Separation of mouse T cell subsets by a fluorescent activated cell sorter using fluorescence-labeled peanut agglutinin.

Nylon non-adherent spleen T cells obtained from concanavalin A-injected mice were labeled with fluorescein-labeled peanut agglutinin and separated into peanut agglutinin-positive (PNA+) cells and peanut agglutinin-negative (PNA-) cells by a fluorescent activated cell sorter. PNA+ cells were found to exert marked suppressive effect on primary anti-sheep red blood cells antibody response, but PNA- cells did not affect the antibody response. From these results and from the sugar-binding specificity of PNA, suppressor T cells are supposed to possess abundant galactosyl residues exposed on the cell surface, which are not masked by sialyl residues.

Animals↗
PubMed1979

Preparation of concanavalin A-ricin A-chain conjugate and its biologic activity against various cultured cells.

For the development of therapeutic agents that possess tissue-specific carriers, a method was devised to synthesize an artificial protein hybrid conjugate containing a moiety which binds to a cell membrane receptor and an active fragment of a toxic protein. By the introduction of an activated sulfhydryl group into concanavalin A (Con A), a conjugate of Con A and the ricin A-chain cross-linked with a disulfide linkage was synthesized. The purified conjugate was studied with regard to its inhibitory activity against protein synthesis in cell-free and cultured cell systems. The Con A-rich A-chain conjugate retained about one-third the inhibitory activity of ricin in a cell-free protein synthesis system. It also was highly toxic to cultured normal cells. These results indicate that the conjugate is a structural and functional analog of ricin and that the original membrane-binding chain (B-chain of ricin) could be replaced by Con A. Transformed cells were insensitive to this conjugate and required a longer preincubation time. The sensitivity of the normal cells was reduced in the presence of local anesthetics.

Animals↗
PubMed1979

Guinea-pig lymphotoxin resistant L-cell sublines.

Guinea-pig lymphotoxin (GLT)-resistant L-cell sublines were isolated, and the altered properties were characterized. Two of them (No. 1 and No. 2 cells) showed the lowest capacity to absorb GLT and substantially reduced ability to bind labelled Ricinus communis agglutinin (RcA). Both the cell-surface proteins and glycoproteins of No. 2 cells were found to be quite different from those of parental L cells. The glycoprotein of molecular weight 140,000, which specifically bound to RcA-Sepharose, was missing in the No. 2 cells extract. These results indicate that the glycoprotein of molecular weight 140,000 is the most probable candidate for the receptor molecule for GLT, and that No. 2 cells and probably No. 1 cells are GLT receptor-deficient cells.

Animals↗