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H Tsubota

Publications and source records attributed to H Tsubota.

At least 37 records · Page 2Linked to original sources
PubMed1992

Assay of gamma-glutamyltransferase with amino acid dehydrogenases from Bacillus stearothermophilus as auxiliary enzymes.

A spectrophotometric assay for serum gamma-glutamyltransferase (gamma-GT, EC 2.3.2.2) based on the increasing absorbance at 340 nm due to NADH formation is described. Using gamma-glutamyl dipeptides as the donor substrate, amino acids formed by the gamma-glutamyl transfer from the donor substrate to the acceptor substrate glycylglycine are stoichiometrically converted by the corresponding amino acid dehydrogenases from Bacillus stearothermophilus to produce their keto acids and NADH. gamma-Glutamylalanine was found to be the most specific and sensitive donor substrate. The method can be mechanized, is free of interference and correlates well with conventional methods.

Amino Acid Oxidoreductases↗
PubMed1992

Regions of the CD4 molecule not involved in virus binding or syncytia formation are required for HIV-1 infection of lymphocytes.

Cell surface-expressed CD4 binds to the envelope glycoprotein of HIV-1 and mediates syncytia formation through interacting with membrane expressed HIV-1 gp120. Further possible roles of the CD4 molecule in the process of cell infection by HIV-1 remain poorly understood. In our study we describe two mAb that recognize the V3/V4 domain of the CD4 molecule. Although these mAb do not inhibit gp120-CD4 binding or HIV-1-induced syncytia formation, they inhibit HIV-1 infection of human PBL. These findings suggest that discrete, definable domains of the CD4 molecule may be involved in interactions after HIV-1 envelope binding that lead to virus entry into the cell.

Antibodies, Monoclonal↗
PubMed1991

Soluble human CD4 elicits an antibody response in rhesus monkeys that inhibits simian immunodeficiency virus replication.

Rhesus monkeys infected with the simian immunodeficiency virus of macaques (SIVmac) demonstrate significant virologic and clinical improvement as a result of treatment with human recombinant soluble CD4 (rsCD4). We show that human rsCD4 does not efficiently inhibit SIVmac replication in bone marrow macrophages of rhesus monkeys and does not significantly augment bone marrow hematopoietic colony formation in vitro. However, plasma of human rsCD4-treated rhesus monkeys does exhibit significant anti-SIVmac activity in vitro. Plasma of these animals efficiently blocks SIVmac replication in peripheral blood lymphocytes and bone marrow macrophages. It also increases granulocyte/macrophage colony formation in vitro by bone marrow cells of SIVmac-infected monkeys. This plasma and the IgG fraction of plasma from a rhesus monkey immunized with human rsCD4 in adjuvant demonstrate reactivity with a soluble form of the rhesus monkey CD4 molecule, exhibit binding to CD4+ but not CD8+ concanavalin A-activated rhesus monkey peripheral blood lymphocytes, and precipitate the CD4 molecule from surface-labeled activated rhesus monkey peripheral blood lymphocytes. Moreover, anti-viral activity is demonstrable in the IgG fraction of plasma from a human rsCD4-immunized monkey. These studies raise the possibility that a modified human CD4 molecule serving as an immunogen might elicit an antibody response that could potentially induce a beneficial therapeutic response in human immunodeficiency virus-infected individuals.

Animals↗
PubMed1991

[Clinical significance of creatine kinase isoform assay by a new reagent based on immunoinhibition method].

Clinical significance of creatine kinase (CK) isoform assay by a new diagnostic reagent based on immunoinhibition method was evaluated. In the method, a monoclonal antibody (CKM-G 01), which inhibits MM3 but not MM1 isoform, was used. Serial serum samples from 143 acute myocardial infarction (AMI) patients were examined in hospitals. Isoform ratio (I.R.: defined as follows; inhibited CK activity/uninhibited CK activity) increased most rapidly (whose peak appeared 8.5 h after onset of AMI), compared with total CK (18.3 h) and CK-MB (16.1 h). In 61 patient samples collected within 4 h from onset, I.R. in 25 samples (41%) exceeded reference interval, whereas total CK in only 17 samples (28%) did it. Reference interval of the I.R. was 0.42 +/- 0.33 (mean +/- SD) in 1,246 normal subjects. These results show that the assay of CK isoforms by the reagents based on immunoinhibition method is useful for earlier detection of AMI.

Antibodies, Monoclonal↗
PubMed1990

Studies of cloned simian immunodeficiency virus-specific T lymphocytes. gag-specific cytotoxic T lymphocytes exhibit a restricted epitope specificity.

CD8+ CTL inhibit the replication of HIV and simian immunodeficiency virus of macaques (SIVmac) in PBL and, therefore, are likely to play an important role in containing the spread of the AIDS virus in infected individuals. We have generated a series of gag-specific lytic T lymphocyte clones from PBL: of an SIVmac-infected rhesus monkey. These T cell clones are CD3+CD8+ and are MHC class I-restricted in their target specificity. They are, therefore, CTL. Interestingly, all gag-specific CTL clones, as well as the gag-specific lytic activity of PBL of this monkey, demonstrated specificity for a single 25 amino acid fragment of the SIVmac gag protein. Moreover, they were restricted in their lytic function by a single MHC class I allele. These findings illustrate a powerful method for cloning AIDS virus-specific T lymphocytes and demonstrate a remarkably restricted epitope specificity of this AIDS virus-specific CTL response.

Animals↗
PubMed1990

CD4-Pseudomonas exotoxin conjugates delay but do not fully inhibit human immunodeficiency virus replication in lymphocytes in vitro.

The CD4 molecule is a high affinity receptor for the human immunodeficiency virus (HIV) envelope glycoprotein (gp160 or gp120). This glycoprotein is expressed on the surface membrane of cells infected with HIV. It has, therefore, been suggested that a soluble form of CD4 might be used as a targeting agent to deliver toxins selectively to cells infected with HIV. We demonstrate that CD4-Pseudomonas exotoxin A (PE) conjugates inhibit the proliferation of gp160-transfected Chinese hamster ovary cells and block HIV replication in virus-infected H9 cells. However, this inhibition of HIV replication appears to be incomplete since virus replication occurs following removal of the toxin conjugates from these cultures. Moreover, CD4-PE conjugates delay but do not inhibit HIV replication in human peripheral blood lymphocytes. These studies suggest that such conjugates should be assessed only as potential adjunctive therapies in the acquired immunodeficiency syndrome.

ADP Ribose Transferases↗
PubMed1989

CD8+CD4- lymphocyte lines can harbor the AIDS virus in vitro.

A detailed definition of AIDS virus-specific T lymphocytes will require the generation and characterization of HIV-1-specific, cloned T cell populations. In our studies, we show that CD8+CD4- lymphocyte lines, derived from PBL of rhesus monkeys infected with simian immunodeficiency virus of macaques and humans infected with HIV-1, can harbor AIDS viruses. CD8+CD4- lymphocyte lines derived from infected individuals are shown to express AIDS virus-encoded proteins and generate reverse transcriptase activity. Infection of these CD8+CD4- lymphocytes is confirmed at the single cell level by the techniques of immunoelectronmicroscopy and two-color immunohistochemistry. This observation suggests that it may prove problematic to generate cloned, functional T lymphocyte populations from AIDS virus-infected individuals and raises the possibility that CD8+CD4- cells may serve as reservoirs for the AIDS viruses.

Acquired Immunodeficiency Syndrome↗
PubMed1989

A cytotoxic T lymphocyte inhibits acquired immunodeficiency syndrome virus replication in peripheral blood lymphocytes.

CD8+ (suppressor/cytotoxic) lymphocytes block replication of HIV-1 or the simian immunodeficiency virus of macaques (SIVmac) in PBL of infected individuals. We now show that these CD8+ lymphocytes undergo clonal expansion in vivo after AIDS virus infection of the individual, suggesting they may be antigen-specific T cells. These CD8+ cells block replication of virus in autologous but not MHC class I-mismatched PBL. The inhibitory lymphocytes express the integrin family molecule 4B4 and the CTL-associated S6F1 epitope of LFA-1. Finally, physical contact is required for the CD8+ lymphocyte-mediated inhibition of AIDS virus replication, since this inhibitory function is blocked by anti-LFA-1 and anti-CD8 mAbs. These studies suggest that the cell that inhibits AIDS virus replication in PBL of infected individuals is a CTL.

Animals↗
PubMed1987

Time dependent impairment of vagally mediated inhibition of noradrenaline release in the dog heart.

The effects of right vagal nerve stimulation on changes in heart rate, mean coronary sinus blood flow, and noradrenaline overflow rate induced by right cardiac sympathetic nerve stimulation were investigated in anaesthetised decentralised, open chest dogs, when autonomic nerve fibres were stimulated tonically at a frequency of 4 or 5 Hz for 2.5 min. Sympathetic nerve stimulation produced a mean(SEM) increase in each of the variables (50(7.0)% in heart rate, 48(6.3)% in coronary sinus blood flow, and 87.0(12.3) ng.min-1 in noradrenaline overflow rate into coronary sinus blood at 30 s), and the increments remained almost constant during continued stimulation. Vagal nerve stimulation induced a decrease of 34(3.4)% in heart rate and of 22(4.5)% in coronary sinus blood flow and a slight reduction (-9(3.2) ng.min-1) in noradrenaline overflow rate at 30 s. Only the decrease in heart rate faded slightly with time. Combined stimulation of the sympathetic and parasympathetic nerves induced a decrease of 19(5.0)% in heart rate and 4(7.5)% in coronary sinus blood flow and an increase of 34.3(12.0) ng.min-1 in noradrenaline overflow rate at 30 s. The decrease in heart rate and coronary sinus blood flow faded, and noradrenaline overflow rate increased significantly to 86.4(17.3) ng.min-1 at 120 s. The temporal changes in heart rate, coronary sinus blood flow, and noradrenaline overflow rate caused by combined nerve stimulation were readily inhibited by treatment with atropine.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

89Y

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Journal Article↗
PubMed1986

Surface marker expression of human B-cell lymphomas.

We have generated a battery of monoclonal antibodies (MAbs) that distinguish different antigen molecules present in human B cells. Two antigen systems, termed L26 and L27, respectively, were expressed in most surface immunoglobulin-positive B cells and thus showed pan-B cell specificity. Two other antigens (L22 and L30) appeared to be expressed mainly on small resting B cells but not on large activated B cells. In contrast with L22 and L30, L29 and L4, the latter of which corresponds to OKT10, were not or little expressed on resting B cells, but were found on these B cells after activation either in-vivo or in-vitro with staphylococcal protein-A (SAC) plus interleukin-2 (IL-2) or with pokeweed mitogen (PWM). We also produced MAb (L10) that detected IL-2 receptors (IL-2R) consistently expressed on in-vitro activated B cells as described above. In contrast with L4, L10 and L29, L30 was lost from in-vitro-activated B cells, following the appearance of either L10 or L29 on these in-vitro-activated B cells. Then, we analyzed antigen profiles of B cell tumors using these MAbs as described above. Common acute lymphatic leukemia (CALL) expressed L4 and L30. B cell type chronic leukemia (B-CLL) and hairy cell leukemia (HCL) possessed most of the B cell antigens as described herein, and furthermore, HCL expressed IL-2R as detected by L10 MAb. In the case of B cell lymphomas, they were phenotypically divided into two groups, corresponding to either early or late activated B cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗