Search PubMed⌕ Search

Biomedical subjects

Y Hashimoto

Publications and source records attributed to Y Hashimoto.

At least 1,333 records · Page 74Linked to original sources
PubMed1986

Dopaminergic amacrine cells in the retina of Japanese dace.

The morphological and physiological identification of the cells in the inner retina of Japanese dace was made by means of intracellular single cell recording and dye injection techniques. Our flat mounts and physiological classification revealed that 97 out of 102 sample cells were amacrine cells except for 3 transient neurons possibly being ganglion cells. Only two cells were identified as interplexiform cells. The double-labeling histochemical technique showed that 17 cells including the two interplexiform cells are dopaminergic neurons. Therefore, 15 of 97 amacrine cells in dace retina were dopaminergic cells, a finding which is different from the previously published data.

Animals↗
PubMed1986

Calmodulin-independent inhibition of platelet phospholipase A2 by calmodulin antagonists.

We tested the effects of calmodulin, two types of calmodulin antagonists, and various phospholipids on the phospholipase A2 activities of intact platelets, platelet membranes, and partially purified enzyme preparations. Trifluoperazine, chlorpromazine (phenothiazines) and N-(6-amino-hexyl)-5-chloro-1-naphthalenesulfonamide (W-7), at concentrations which antagonize the effects of calmodulin, significantly inhibited thrombin- and Ca2+ ionophore-induced production of arachidonic acid metabolites by suspensions of rabbit platelets and Ca2+-induced arachidonic acid release from phospholipids of membrane fractions, but not phospholipase A2 activity in purified enzyme preparations. The addition of acidic phospholipids, but not calmodulin, stimulated phospholipase A2 activity in purified enzyme preparations while decreasing its Km for Ca2+. The dose-response and kinetics of inhibition by calmodulin antagonists of acidic phospholipid-activated phospholipase A2 activity in purified preparations were similar to those of Ca2+-induced arachidonic acid release from membrane fractions. Calmodulin antagonists were also found to inhibit Ca2+ binding to acidic phospholipids in a similar dose-dependent manner. Our results suggest that the platelet phospholipase A2 is the key enzyme involved in arachidonic acid mobilization in platelets and is regulated by acidic phospholipids in a Ca2+-dependent manner and that calmodulin antagonists inhibit phospholipase A2 activity via an action on acidic phospholipids.

Animals↗
PubMed1986

Monoclonal antibodies that inhibit activation and proliferation of lymphocytes. II. Requisite role of the monoclonal antibody-defined antigen systems in activation and proliferation of human and rat lymphocytes.

A murine monoclonal antibody (MoAb) B3 to rat cells and MoAb HBJ127 and HBJ98 to human cells were found previously to recognize the homologous antigen systems (gp130 in the rat and gp125 in the human) which are predominantly distributed on the cell surface of proliferating cells of the respective species, and the expression of the antigen systems in lymphocytes were indicated previously to correlate closely with the activation and proliferation of the lymphocytes. In this respect, the in vitro effects of these MoAb on the nucleic acid synthesis, cell cycles, or proliferation of stimulated rat and human lymphocytes were examined by use of T cell-enriched and B cell-enriched cell populations. The addition of B3 MoAb to cultures diminished Con A-induced or allogeneic mixed lymphocyte culture-induced rat T cell proliferation and lipopolysaccharide-induced rat B cell proliferation, whereas B31 MoAb, which is unreactive with the gp130 antigen, did not inhibit these lymphocyte responses. Similarly, both HBJ127 and HBJ98 MoAb could inhibit the human lymphocyte proliferation in vitro, although HBJ127 MoAb showed about eight times greater inhibitory activity than did HBJ98 MoAb; HBJ127 MoAb almost completely inhibited the DNA synthesis of the Con A-stimulated lymphocytes at concentrations higher than 13 micrograms/ml. The flow cytometric analysis of the cellular nucleic acid contents with acridine orange-stained cells showed that when B3 MoAb and Con A were simultaneously added to unstimulated rat T cells, progression of the cell cycle was blocked at the G0 to G1 transition. In this culture condition, the appearance of the B3-defined antigen was arrested in a moderate level, as determined with fluorescein-stained cells. On the addition of B3 MoAb to the culture of the T cells after 24-hr Con A stimulation, the MoAb also strongly inhibited the cellular DNA synthesis, but it did not arrest the cell cycle at a certain phase and did not modulate the corresponding antigen. These data suggest that the B3 MoAb-defined antigen on the rat lymphocytes and the HBJ127/HBJ98 MoAb-defined antigen on the human lymphocytes may play some requisite roles not only in lymphocyte activation but also in the subsequent progression through the cell cycle to proliferate.

Animals↗
PubMed1986

Monoclonal antibodies that inhibit activation and proliferation of lymphocytes. I. Expression of the antigen on monocytes and activated lymphocytes.

It has been shown previously that HBJ127 and HBJ98 monoclonal antibodies raised against a human bladder cancer cell line, and B3 monoclonal antibody against a rat bladder cancer cell line recognized unique cell surface antigens abundant in proliferating cells of the corresponding species. Distribution of the antigens and kinetics of the appearance on human and rat lymphoid cells were examined by means of flow cytometry. Rat macrophages and human peripheral blood monocytes were stained strongly with the B3 and HBJ127 monoclonal antibodies, respectively. With regard to lymphocytes, the expression of the B3-defined antigen on rat lymphocytes was found to have a negative correlation with the maturation of the lymphocytes; the antigen was most abundant in bone marrow cells, less abundant in thymocytes, and least abundant in spleen, lymph node, and peripheral blood lymphocytes. Similarly, the HBJ127-defined antigen on human peripheral lymphocytes was negligible. On activation with Con A or alloantigens, however, both rat and human T lymphocytes did strongly express these antigens. Activation of human or rat B cells with lipopolysaccharide also resulted in the augmented expression of these antigens. Kinetics studies revealed that the antigen expression was readily manifested within 12 hr on activation of rat or human T cells with Con A, was augmented progressively with culture time, and reached a plateau within 36 hr. This somewhat earlier appearance of these antigens apparently preceded the manifestations of the IL 2 receptor (Tac antigen) and the augmented DNA synthesis. The B3-defined antigen on Con A-stimulated T cells was more rich on the lymphocytes in S and G2/M phases than those in G1 phase, and the expression was not significantly affected by the addition of hydroxyurea, but was moderately inhibited by the addition of sodium butylate. These results suggest that the appearance and expression of the B3-defined antigen and probably also those of the HBJ127/HBJ98-defined antigen are correlated with lymphocyte activation and subsequent progression through the cell cycle.

Animals↗
PubMed1986

Augmentation of the therapeutic efficacy of adoptive tumor immunotherapy by in vivo administration of slowly released recombinant interleukin 2.

Immunization of C57BL/6 mice with MMC-treated syngeneic lymphoma cells, MBL-2, caused the generation of antitumor effector cells in vivo and the immunized mice permanently rejected viable MBL-2 lymphoma cells. Both plastic nonadherent T cells and plastic adherent M phi obtained from MBL-2 immunized mouse peritoneal exudate cells revealed strong cytotoxic activity against MBL-2 lymphoma cells, whereas immune spleen cells were not highly active against MBL-2 lymphoma cells in vitro. However, systemic adoptive transfer of immune spleen cells into the MBL-2-bearing mice by i.v. infusion in conjunction with i.p. cyclophosphamide (100 mg/kg) treatment cured the mice of tumor. This therapeutic efficacy of immune spleen cells was reflected by the number of transferred effector cells and over 5 X 10(7) immune spleen cells were required to cure the mice completely. The cells mediating in vivo rejection of MBL-2 lymphoma cells were Thy 1.2+ T cells. This ACIT was specific against MBL-2 lymphoma cells and had no effect on the growth of other syngeneic tumors, B16 melanoma or BMC6A fibrosarcoma. In vivo administration of recombinant interleukin 2 (r-IL2) combined with ACIT greatly modulated the cure rate of tumor-bearing mice. In addition, we found that slowly released r-IL 2 administratered from an ALZET miniosmotic pump was more effective in augmenting the therapeutic efficacy of immune spleen cells in ACIT than a single injection of the same total dose of r-IL 2.

Animals↗
PubMed1986

Evidence for the presence of a genome-linked protein in infectious flacherie virus.

The genomic RNA of infectious flacherie virus (IFV), an insect picornavirus, was shown to contain a covalently attached substance which can be labeled with 125I-Bolton and Hunter reagent. This substance was found to be a protein covalently linked to the virus genome, because it cosedimented and was copurified with the viral RNA and was degraded by proteinase K but not by RNases. The molecular weight of the protein was found to be 11,500 in the sodium dodecyl sulfate polyacrylamide gel electrophoresis. This protein apparently corresponds to viral protein genome-linked (VPg) detected in mammalian picornaviruses, because it was not required for the synthesis of viral proteins in a cell-free translation system of a rabbit reticulocyte lysate and because it was not immunochemically related to the virus capsid proteins. The results presented here leave a possibility that insect picornavirus also replicates its RNA by using VPg as a primer as reported for mammalian picornaviruses. These observations on VPg of an insect picornavirus are discussed in the view point of comparative virology.

Bombyx↗
PubMed1986

Generation of lymphokine-activated killer (LAK) cells from tumor-infiltrating lymphocytes.

Culture of tumor-infiltrating lymphocytes (TIL) containing about 20% BMC2 tumor cells with recombinant human interleukin 2 (rIL-2) resulted in the diminish of tumor cells and the growth of lymphocytes. These IL-2-activated lymphocytes showed a strong cytotoxic activity against not only syngeneic tumor cells but also allogeneic tumor cells. Such broad-reactive killer cells, termed lymphokine-activated killer (LAK) cells, are also inducible from spleen cells by in vitro activation with IL-2. However, LAK cells generated from TIL (TIL-LAK) showed higher cytotoxic activity against BMC2 than LAK cells generated from spleen cells (S-LAK). Furthermore, it was demonstrated that TIL-LAK cells revealed marginal cytotoxic activity against normal Con A blasts and YAC-1 cells as opposed to S-LAK. Flow cytometric analysis of TIL-LAK indicated that TIL-LAK cells mainly consisted of Thy 1.2+, Ly 2+, asialo GM1+ cells. TIL-LAK cells displayed not only in vitro cytotoxicity but also in vivo anti-tumor activity. Furthermore, it was also confirmed that TIL-LAK cells could be induced in autochthonous mouse tumor systems and human gastric tumor systems.

Animals↗
PubMed1986

Recombinant interleukin 2 allows the differentiation of Thy 1.2+ LAK cells from nude mouse spleen cells.

Culture of nude mouse spleen cells with recombinant human interleukin 2 (r-IL 2) resulted in the proliferation and generation of lymphokine-activated killer (LAK) cells which could lyse a variety of tumor cells. Flow cytometry study indicated that nude mouse spleen cells contained almost no Thy 1.2+ cells at the initial times of the culture, whereas LAK cells obtained from nude mouse spleen cells by culture with r-IL 2 (nude-LAK cells) expressed high intensity of Thy 1.2 antigen and lymphokine-activated cell-associated (LAA) antigen. The cytotoxic activity of nude-LAK cells was greatly reduced by treatment with anti-Thy 1.2 antibody plus complement but not with anti-Ly 1.2 or Ly 2.2 antibody plus complement treatment. Moreover, nude-LAK cells were resistant to the treatment with anti-asialo GM1 antibody plus complement, in contrast to resident nude natural killer (NK) cells. These data strongly suggested that r-IL 2 allowed the nude mouse spleen cells to differentiate into Thy 1.2+, Ly 1-,2-, asialo GM1- LAK cells which were distinct from Thy 1.2+, Ly 2+, asialo GM1- LAK cells induced from normal mouse spleen cells.

Animals↗
PubMed1986

PHI structural requirements for potentiation of glucose-induced insulin release.

Immunoreactive PHI was detected in rat pancreas. The potentiating effect of 10(-9) M PHI upon insulin release from the isolated perfused rat pancreas was significant and most consistent when 250 mg% glucose was present in the perfusion medium. PHI(1-15) retained a substantial potentiating effect on insulin release, while PHI(14-27) was essentially inactive. Replacement of amino-terminal decapeptide portion of the PHI molecule with the corresponding part of VIP resulted in a drastic decrease of the potentiating effect of PHI on insulin release. 10(-8) M PHI(14-27) substantially diminished the potentiation by 10(-9) M PHI while PHI(1-15) was without an inhibitory effect. The present results indicate that the PHI active site for potentiation of glucose-induced insulin release resides in the amino-terminal segment of the molecule but requires the carboxyl terminal segment primarily for binding to exhibit full biological activity.

Animals↗
PubMed1986

Changes in blood urea nitrogen (BUN) concentration during pregnancy in the rat with or without obstructive uremia.

Bilateral ureteral ligation changes the blood urea nitrogen (BUN) concentration in pregnant and non-pregnant rats. Marked increases of the BUN concentration occurred in both pregnant and non-pregnant specimens after ligation. The BUN concentration in sham-ligated rats did not change from day 16 through 19 of pregnancy, but increased on day 20 of pregnancy and thereafter. There was no significant difference in BUN between ligated pregnant rats on days 16 and 17 of pregnancy and ligated non-pregnant rats. As pregnancy progressed from day 18 onward, the BUN in ligated pregnant rats decreased when compared with that of ligated non-pregnant rats, but did not reach the level in sham-ligated pregnant rats. The BUN of mothers and fetuses both in the ligated and the sham-ligated groups were similar. Amniotic fluid urea nitrogen levels were higher than in blood on late fetal days. In ligated mothers, a significant relationship between maternal BUN and the number of fetuses was noted on day 22 of pregnancy. These results suggest that the fetal kidney becomes functional for excreting urea in late fetal life.

Amniotic Fluid↗
PubMed1986

T-cell antigen-receptor genes in autoimmune mice.

The developmental patterns of rearrangement and expression of the T-cell antigen-receptor genes are precisely regulated during T-cell differentiation and education. The beta- and gamma-subunit RNAs of the T-cell receptor are abundantly expressed in immature thymocytes. In mature thymocytes the alpha- and beta-subunit RNAs are preferentially expressed, whereas there is minimal expression of the gamma RNA. Although aspects of the pattern of known organization and rearrangement of the T-cell receptor gene in the thymus have been studied and the concept of a thymus selection process generally has been accepted, the cellular and molecular basis of thymus education remains obscure. Certain strains of mice with predilections for autoimmunity demonstrate T-cell developmental abnormalities. This is especially true for the lpr/lpr or gld/gld genotypes, in which the major population of peripheral T cells is developmentally disturbed. We have studied the development, expression, and rearrangement of T-cell receptor genes in the C3H/HeJ gld/gld mouse. Our results indicate a high level of expression of the beta and alpha RNAs in C3H/HeJ gld/gld T cells residing in the periphery. In addition, the beta-subunit gene of gld/gld peripheral T cells undergoes more rearrangements than does its normal C3H/HeJ T-cell counterparts. We speculate that this rearrangement pattern and high level of T-cell receptor mRNA reflects an abnormality or deficit in a thymus selection process that permits emigration of T cells with nonfunctionally rearranged T-cell receptor genes to secondary lymphoid organs. However, the normal level of gamma-subunit RNA expression argues that gamma-subunit gene rearrangements are distinct from processes related to alpha- and beta-subunit selection.

Animals↗
PubMed1986

Isolation and characterization of type V collagen from human post-burn granulation tissues.

Sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis of pepsin-solubilized collagens from post-burn granulation tissues revealed that type V collagen consisted of 3 alpha chains: alpha 1(V), alpha 2(V), and alpha 3(V). The mean value (0.12 +/- 0.01 SD) of the type V/type I ratio in the granulation tissues was significantly higher (p less than 0.001) than that (0.03 +/- 0.01 SD) of the ratio in normal skin. The average ratio of alpha 1(V):alpha 2(V):alpha 3(V) of type V collagen purified from the granulation tissues was determined to be about 5:3:1. SDS-polyacrylamide gel electrophoresis patterns of 3 alpha chains were not affected in the presence or absence of 2-mercaptoethanol. Purified type V collagen was degraded by bacterial collagenase, but remained intact after tadpole collagenase digestion, in contrast to type I and type III collagens. Amino acid analyses of each alpha chain separated on SDS-gel electrophoresis of type V collagen revealed that all 3 alpha chains of type V collagen were poor in alanine, rich in hydroxylysine, and had high ratios of hydroxylysine/lysine, which are typical features of type V collagen. The purified type V collagen was further fractionated by ammonium sulfate into 2 molecular species, [alpha 1(V)]2 alpha 2(V) and alpha 1(V)alpha 2(V)alpha 3(V). Our data demonstrate that type V collagen in preparations from human post-burn granulation tissues consists of 3 alpha chains and can be resolved into 2 distinct heterotrimers.

Amino Acids↗
PubMed1986

Effect of passive administration of alloantiserum containing antibody against putative acceptor(s) for T cell-replacing factor (TRF) in the neonatal stage on development of B cell activity responsive to TRF.

Previously, we showed that the antiserum raised in male (DBA/2Ha X BALB/c)F1(DCF1) mice (T cell-replacing factor [TRF]-low response animals) by immunizing them with activated B cells from BALB/c mice (TRF-high-responders) contained antibodies against putative TRF-acceptor site(s). We have now evaluated the hypothesis that neonatal treatment of mice with the above antiserum suppresses the development of B cells responsive to TRF. Male DCF1 mouse anti-BALB/c B-cell antiserum or normal DCF1 mouse serum as a control was injected into BALB/c mice within 24 hr after birth. In the antiserum-treated mice, no augmented primary immunoglobulin M (IgM) antibody responses to sheep red blood cells (SRBC) were observed under the conditions in which markedly augmented IgM anti-SRBC responses were induced in control BALB/c mice, suggesting that development of B cells reacting with male DCF1 mouse anti-BALB/c B-cell antiserum is suppressed by the neonatal treatment with the antiserum. Furthermore, the development of B cell activity responsible for helper factors derived from T cells, such as TRF, was markedly suppressed in the neonatally antiserum-treated mice, whereas activity of B cells capable of interacting directly with helper T cells through antigen-bridges was not significantly affected by the same treatment. Such suppression of the B cell activity could be induced only when the antiserum was administered within 48 hr after birth. Moreover, neonatal treatment of mice with the antiserum induced suppressed responsiveness of B cells to a T-independent type 2 antigen, TNP-Ficoll. Neither serum-borne suppressive serum components nor suppressor cells were detected by the system employed. These results support the hypothesis that TRF responsive B cells constitute a subpopulation distinct from the other B cells capable of cooperating with helper T cells via cognate interaction.

Animals↗
PubMed1986

Topical PUVA treatment increases epidermal beta-adrenergic adenylate cyclase responsiveness.

The effects of topical PUVA treatment on the epidermal cyclic AMP system were investigated. 8-methoxypsoralen (8-MOP), 0.3% in ethanol was applied to the backs of pigs which were then irradiated with UVA. A significant increase in the epidermal beta-adrenergic adenylate cyclase response was observed 24 h after low (1.1 J/cm2) and moderate (2.1 J/cm2) dose irradiation. There was no significant change in the adenosine- or histamine-mediated adenylate cyclase responses. 8-MOP application or UVA irradiation alone had no effect on the beta-adrenergic adenylate cyclase response. PUVA treatment with a higher irradiation dose (4.2 J/cm2) produced no increase in the beta-adrenergic response and adenosine- and histamine-mediated adenylate cyclase responses were decreased. Cyclic AMP phosphodiesterase activity was decreased by PUVA treatments using UVA doses of 1.1 and 2.1 J/cm2; however, the change was not statistically significant. The increased beta-adrenergic response was also observed in the presence of the cyclic AMP phosphodiesterase inhibitor, isobutylmethylxanthine. These results indicate that epidermal adenylate cyclase responsiveness is affected by topical PUVA treatment in vivo.

1-Methyl-3-isobutylxanthine↗
PubMed1986

Pharmacokinetics and antiarrhythmic activity of ajmaline in rats subjected to coronary artery occlusion.

The pharmacokinetics and the antiarrhythmic action of intravenous ajmaline were investigated in anaesthetized rats subjected to coronary artery occlusion. Ajmaline (0.125-2 mg kg-1, i.v. given just after occlusion) suppressed arrhythmias in a dose-dependent manner, judged by the reduction of premature ventricular complexes. The incidence of malignant arrhythmias (ventricular tachycardia and fibrillation) was preferentially suppressed at the higher doses of ajmaline (1 and 2 mg kg-1). Coronary occlusion induced a change in pharmacokinetics of ajmaline (2 mg kg-1) and its total body blood clearance was significantly decreased from 56.6 ml min-1 kg-1 in sham-operated rats to 43.1 ml min-1 kg-1 in rats after coronary occlusion. Ajmaline exhibited a significantly increased negative dromotropic action (increased PQ interval) in rats after coronary occlusion compared with that in sham-operated rats. The difference seems to be due to the pharmacokinetic change since the concentration-effect relationship was similar in the two groups of rats. We suggest that the measurement of drug levels is important in the assessment of antiarrhythmic agents.

Ajmaline↗
PubMed1986

Enhanced endothelial cell proliferation in acute Kawasaki disease (muco-cutaneous lymph node syndrome).

Paired sera from 30 patients with muco-cutaneous lymph node syndrome (Kawasaki disease) were studied for possible effects on human vascular endothelial cells growth in vitro. The majority of sera from acute phase muco-cutaneous lymph node syndrome patients significantly enhanced endothelial cell proliferation more than those from convalescent phase patients, infectious diseases patients, and age-matched normal controls. This stimulation was considered to be specific for EC since muco-cutaneous lymph node syndrome sera did not enhance fibroblast growth more than normal sera. Fractionation of the serum with gel filtration failed to clearly detect the molecular properties of this effect, although both heavy and light material possessed this activity. Extensive search for circulating immune complex in muco-cutaneous lymph node syndrome sera were negative, suggesting that the enhanced endothelial cell proliferation was due to serum components other than immune complexes.

Antigen-Antibody Complex↗