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Biomedical subjects

H Osawa

Publications and source records attributed to H Osawa.

At least 181 records · Page 10Linked to original sources
PubMed1986

Electrocochleographic study of low-tone hearing loss without vertigo.

Auditory nerve action potential (AP), cochlear microphonics (CM) and summating potential (SP) were recorded from 6 patients with low-tone hearing loss without vertigo. All these cases showed high AP and -SP amplitude and satisfactory CM response. These findings resembled the electrocochleographic findings of type 1, which is an early stage of Ménière's disease. Hearing returned to normal range in half of the cases but remained hardly changed in the other half. The difference between these two groups could not be clarified electrocochleographically. On the other hand, low-tone hearing loss due to retrolabyrinthine lesion and due to familial sensorineural deafness was shown to have a low AP amplitude.

Adolescent↗
PubMed1986

Cells reacting with the monoclonal anti-IL-2 receptor antibody AMT-13 in the regenerating thymus of irradiated mice.

The proportion and anatomical localization in murine thymus of T cell subpopulations, including those which are defined by the monoclonal anti-interleukin 2 (anti-IL-2) receptor antibody AMT-13, were studied by flow cytofluorometry and by immunohistochemical methods, both in irradiated and in normal mice. As a consequence of irradiation the proportion of AMT-13 positive cells and that of Lyt-1 positive cells were markedly enhanced, while the proportion of Lyt-2 positive cells was reduced. The vast majority of the AMT-13 positive cells both in normal and in irradiated thymi were located in the subcapsular area of the thymic cortex, whereas the irradiation resistant Lyt-1 positive cells were located in the medulla. These findings are compatible with the view that, similar to the developing thymus in the mouse embryo, in the regenerating adult thymus, AMT-13+ cells include the activated pro-thymocytes that repopulate the irradiated thymus.

Animals↗
PubMed1986

Effects of in-vivo administration of a monoclonal antibody specific for the interleukin-2 receptor on the acute graft-versus-host reaction in mice.

Parental strain T lymphocyte injected into F1 mice respond to allogeneic MHC antigens and so induce the symptoms of a graft-versus-host reaction (GVHR). We have measured the local GVHR by the popliteal lymph node assay, and showed the suppression of the local GVHR in mice by treatment with the monoclonal antibody (MoAb) AMT-13 which is specific against the interleukin 2 (IL-2) receptor on activated mouse lymphocytes. The inhibitory effect of the AMT-13 administration was comparable with the suppression of the local GVHR by treatment with L3T4, an MoAb directed against the T helper subset. The L3T4 administration caused a dramatic decrease in the proportion of the cells with the L3T4 phenotype in the circulation and a marginal reduction of these cells in the lymph nodes. In contrast, the AMT-13 treated mice showed no changes in the distribution of the T lymphocyte subsets besides those in the GVHR-stimulated lymph nodes. Obviously, only the small subset of antigen-activated IL-2 receptor-bearing lymphocytes was influenced by treatment with AMT-13. MoAb directed against antigens whose expression is restricted to activated lymphocytes, such as the IL-2 receptor, might become useful for a short term immunosuppression with limited side effects.

Animals↗
PubMed1985

A case of biliary cystadenocarcinoma with recurrent jaundice. Diagnostic evaluation of computed tomography.

A 73-year-old male patient with biliary cystadenocarcinoma and episodes of recurrent jaundice is reported. This very rare tumor was suggested as a possible diagnosis by the computed tomographic findings showing intrahepatic cystic masses with septations and papillary projections. The diagnosis of the mucin-producing tumor was supported by aspiration of mucinous bile with a cannule inserted endoscopically via the major duodenal papilla. The computed tomographic findings and the diagnosis were verified by pathologic studies made on the material obtained surgically. The mucinous bile is assumed to have been responsible for the recurrent jaundice.

Aged↗
PubMed1985

Rat lymphoid cell lines producing human T cell leukemia virus. II. Constitutive expression of rat interleukin 2 receptor.

Three rat lymphoid cell lines (TARS-1, TARL-2, and TART-1) (12) transformed by human T cell leukemia/lymphoma virus I (HTLV-I) had rearrangement of the beta chain gene of the T cell antigen receptor, and had integrated proviral DNA from HTLV-I in their genomes. As is the case with adult T cell leukemia (ATL)-derived human T cell lines transformed by HTLV-I, these rat cell lines unequivocally expressed interleukin 2 (IL-2) receptor, as determined by radiolabeled IL-2 binding. By Scatchard plot analysis, one of the cell lines, TART-1, proved to have high affinity receptors (Ka = 1.3 X 10(11)/M and 8.8 X 10(9)/M). Rat IL-2 receptor, not human IL-2 receptor, was expressed on HTLV+ rat cell lines, as demonstrated by the fact that they expressed antigens reactive with monoclonal antibodies (ART-18) against rat IL-2 receptor, but not with anti-Tac antibodies. The collective evidence indicates that the endogenous IL-2 receptor gene is activated in human and rat lymphoid cell lines with HTLV-I production. The mechanism of abnormal IL-2 receptor expression in HTLV infection is discussed.

Animals↗
PubMed1985

Nucleotide sequence of mouse IL-2 receptor cDNA and its comparison with the human IL-2 receptor sequence.

We have cloned cDNA encoding the mouse interleukin-2 (IL-2) receptor from a murine T cell line, CTLL using human IL-2 receptor cDNA as probe. COS 7 cells transfected with the cDNA expressed the antigen recognized by the monoclonal antibody against the murine IL-2 receptor. The cDNA identified 4 species of mRNA (4.5, 3.5, 2.2 and 1.5 kb) of the mouse IL-2 receptor in CTLL cells. Difference in the length of mRNA seems to be ascribed to the variable length of the 3' untranslated sequence. Total nucleotide sequence (approximately 1400 bp) of this cDNA was determined and compared with the human receptor. The nucleotide and amino acid sequences of the IL-2 receptor are 70% and 60%, respectively, homologous in average between the two species. The comparison has revealed several conserved regions localized to particular exons such as transmembrane and cytoplasmic portions, suggesting that these regions are important for receptor function and its regulation.

Amino Acid Sequence↗
PubMed1985

Direct demonstration that the monoclonal antibody AMT-13 and interleukin 2 bind to the same molecule.

125I-labeled surface molecules from mouse T lymphoblasts were fractionated by affinity supports coupled with recombinant interleukin 2 (IL2) and the monoclonal antibody (mAb) AMT-13. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis demonstrated that two molecules of approximately 55 kDa and of approximately 180 kDa were bound in both cases. Sequential precipitation and SDS-PAGE analysis of the precipitated molecules revealed that only the approximately 55-kDa molecule eluted from AMT-13 mAb support was rebound to IL2 affinity support. In addition, IL2 inhibited specifically the binding of 125I-labeled AMT-13 mAb to T lymphoblasts. Thus the results directly demonstrate that the a approximately 55-kDa cell surface molecule represents the IL2-binding protein and that the mAb AMT-13 reacts with this molecule.

Animals↗
PubMed1985

The mode of action of the calcium ionophore A23187 on T cell proliferation. I. The ionophore does not replace lymphokines but acts via induction of IL-2 production on IL-2 responsive cells.

The two compounds, the calcium ionophore A23187 and phorbol myristate acetate (PMA), which are not mitogenic for mouse thymocytes, induce proliferation when added in combination to thymocyte cultures. Short exposure to PMA renders the cells responsive to IL-2, added exogeneously. The cells rendered IL-2-responsive by PMA are enriched in the more mature peanut agglutinin (PNA)-negative population. The ionophore does not render PNA-negative thymocytes IL-2-responsive, but induces proliferation of PMA-pulsed PNA-negative thymocytes. PMA-pulsed PNA-negative thymocytes proliferating in response to either exogeneous IL-2 or ionophore express IL-2 receptors. However, the ionophore does not mimic IL-2 action but acts indirectly by induction of both IL-2 production and of IL-2 receptor expression via IL-2. This view is based on the following findings: 1) IL-2 could be detected in supernatants derived from PMA-preactivated thymocytes incubated with the ionophore; 2) The IL-2-induced proliferation, as well as the ionophore-induced proliferation, was specifically blocked by a monoclonal anti-IL-2-receptor antibody; 3) The proliferation induced by exogeneous IL-2, as well as that induced by the ionophore, could be specifically inhibited by metabolically blocked T lymphoblasts carrying IL-2 receptors competing with the responder cells for the available IL-2 added or produced in the system.

Animals↗
PubMed1985

Studies on interleukin 2 receptor expression and IL-2 production by murine T cell lymphomas.

In order to study the possible role of the T-lymphocyte growth factor, Interleukin 2 (IL-2), and/or of the IL-2 receptor in the autonomous growth of leukaemic cells, 15 mouse leukaemic cell lines of various aetiology were analyzed for (i) IL-2 receptor expression and (ii) for the capacity to secrete IL-2. Several but not all of the cell lines tested were IL-2 receptor positive. The cells constitutively expressing IL-2 receptors at their surface could not be stimulated to secrete IL-2. Cell producing and secreting IL-2 did not express detectable amounts of IL-2 receptors at their surface. It has been demonstrated that proliferation of the leukaemic cells was independent of exogenous IL-2. The monoclonal anti-IL-2 receptor antibody AMT-13 inhibited IL-2 dependent proliferation of activated normal T-lymphocytes but failed to inhibit the growth of IL-2 receptor expressing leukaemic cells. The results argue against the autocrine stimulation hypothesis but do not exclude the possibility of involvement of functionally altered IL-2 receptors on autonomous cell growth.

Animals↗
PubMed1985

Production of Listeria-specific rat T-cell clones and role of interleukin-2 receptors in regulation of Listeria-dependent T-cell clone growth in vitro.

Splenic T lymphocytes from rats immunized with the facultative intracellular bacterium Listeria monocytogenes were cloned by the limiting-dilution technique in the presence of accessory cells, heat-killed L. monocytogenes as antigen, and conditioned medium containing interleukin-2. The cloned rat T-cells were Listeria-specific cells, and their proliferation depended on class II-restricted antigen presentation by accessory cells. As demonstrated by their reactivity to the monoclonal antibody W3/25, the clones were of helper cell phenotype. Cloned-cell proliferation depended on repeated (or continuous) exposure to antigen. When antigen was omitted from the system, cell growth subsided over time, and cells finally ceased to grow. By the use of the monoclonal antibody ART-18, which recognizes the interleukin-2 receptor, it was shown that cessation of growth was accompanied by the disappearance of interleukin-2 receptors from the cell surface. The addition of antigen to the culture resulted in the reexpression of interleukin-2 receptors and concomitant resumption of proliferation.

Animals↗
PubMed1985

Inhibition of IL 2-dependent proliferation of rat T lymphoblasts by the monoclonal antibody ART62 which reacts with MHC class 1 antigens.

During the course of studies designed to obtain monoclonal antibodies (mAb) that recognize the rat interleukin 2 receptor, a mouse IgG1 mAb (ART62) was identified which inhibits the interleukin 2 (IL 2)-dependent proliferation of rat T lymphoblasts without affecting the binding of IL 2 to such cells. In order to characterize the cell surface components that react with the mAb ART62, T lymphoblasts were surface-labeled with 125I, and the radioactive molecules were immunoprecipitated by the antibody analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The mAb ART62 precipitated two major components of 48,000 m.w. and 12,000 m.w., respectively, which were different from those which react with the anti-IL 2-receptor antibody ART18, a molecule of 50,000 to 55,000 m.w. Sequential immunoprecipitation studies revealed that the mAb ART62 reacts with the MHC class 1 antigen that reacts with the classical anti-rat MHC class 1 mAb OX18, and vice versa. In contrast to the mAb ART62, OX18 that does not affect and several other mAbs known to inhibit the rat MLR failed to inhibit IL 2-dependent proliferation of rat T lymphoblasts. In contrast to the anti-IL 2 receptor antibody ART18, ART62 effectively inhibited IL 2-driven proliferation even when added to cells already committed to proliferate by IL 2-IL 2 receptor interaction. These data raise the possibility that MHC class 1 antigens could be involved in the chain of reactions mediating the signals required for cell proliferation.

Animals↗
PubMed1985

Functional analysis of mononuclear cells infiltrating into tumors. II. Differential ability of mononuclear cells obtained from various tissues to produce helper factors that are involved in the generation of cytotoxic cells.

The requirement of CGF in the generation of cytotoxic cells against syngeneic tumor cells (T-9) and in the rejection of transplanted T-9 cells has been investigated. Spleen cells obtained from sensitized rats showed strong cytotoxicity against 51Cr-labeled T-9 cells upon incubation with CGF for 48 hr. Human recombinant IL 2 and rat IFN failed to generate cytotoxic cells from spleen cells of sensitized rats. CGF are produced by spleen cells upon inoculation of T-9 cells into sensitized rats as a host in vivo immune response. Production of CGF preceded the appearance of cytotoxic cells in regional lymph node and tumor tissues. In those rats, inoculated tumor cells were eventually rejected. In contrast, spleen cells failed to produce CGF upon inoculation of T-9 cells in unsensitized rats. Cytotoxic cells were not detected in unsensitized rats, and inoculated tumor grew in those rats. Thus, CGF is likely to be involved in the generation of cytotoxic cells and in the rejection of inoculated syngeneic tumor cells. A Mono Q anion-exchange column with an FPLC system allowed the chromatographic separation of CGF from IL 1, IL 2, IL 3, and CSF.

Animals↗
PubMed1985

Immunohistochemical localization of cells reacting with monoclonal antibodies directed against the interleukin-2 receptor of murine, rat and human origin.

Recently, species specific monoclonal antibodies, directed against the interleukin-2 (IL-2) receptor of murine, rat and human origin, have been produced. In this study we demonstrate with immunohistological methods that cells reacting with these antibodies are present in normal primary and secondary lymphatic organs. The cells are exclusively localized in T cell-dependent areas, and their number increased as a result of immunization.

Animals↗
PubMed1984

Partial characterization of the putative rat interleukin 2 receptor.

T lymphoblasts of rat origin were (a) surface labeled with 125I and (b) internally labeled with 3H-marked sugars. Cell lysates were purified by immunoabsorption using the putative anti-rat interleukin 2 (IL2) receptor monoclonal antibody ART18 . The purified material was subjected to sodium dodecyl sulfate polyacrylamide gel electrophoretic analysis. Two specific membrane components were detected: a 50-kDa major and a 36-kDa minor component in reducing and a 45-kDA major and a 72-kDa minor component in nonreducing conditions, respectively. Both components were found to be susceptible to trypsinization and to neuraminidase treatment. 3H-labeled sugars were incorporated into the major component. The results indicate that the rat IL2 receptor is either a 50-kDa glycoprotein or a 36-kDa molecule, or that both components are part of the receptor molecule.

Animals↗