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K Isobe

Publications and source records attributed to K Isobe.

At least 19 recordsLinked to original sources
PubMed1996

Entire hemithorax irradiation following complete resection in patients with stage II-III invasive thymoma.

PURPOSE: To evaluate the feasibility and efficacy of prophylactic entire hemithorax irradiation (EH) in addition to mediastinal irradiation (MRT) following a complete resection in Stage II-III invasive thymoma. METHODS AND MATERIALS: Forty-three patients with invasive thymoma treated with surgery and radiation therapy between 1978 and 1993 were analyzed retrospectively. All 43 patients underwent a complete surgical resection and were judged to have Masaoka's Stage II-III invasive thymoma. Of these, 23 patients received EH and MRT (EH-MRT) and the remaining 20 received MRT. Of the 23 patients with EH-MRT, 11 were Stage II and 12 Stage III. Of the 20 with MRT, 11 were Stage II and 9 Stage III. In most cases, EH was 15 Gy per 15 fractions over 3 weeks (without lung compensation calculation). In both the EH-MRT and MRT group, the total radiation doses to the mediastinum were similar with a median of 40 Gy. The median follow-up time after surgery was 63 months and no patients were lost to follow-up. RESULTS: Only one of the 23 patients with EH-MRT relapsed. On the other hand, eight of the 20 with MRT relapsed, six of whom died of disease. The pleura was the most common site of failure. At 5 years, the relapse-free rate was 100% for those receiving EH-MRT and 66% for those with MRT (p = 0.03); the overall survival rate was 96% for those with EH-MRT, and 74% for those with MRT (p: not significant). The only significant treatment-related complication was radiation pneumonitis requiring treatment, in one patient who received MRT and three who received EH-MRT, including one death of a 72-year-old man and one 68-year-old woman with severe lung fibrosis. CONCLUSION: Except for elderly patients, EH-MRT following a macroscopically complete resection appears to be safe and feasible, and can reduce intrathoracic relapses.

Adult↗
PubMed1995

Dissociated control by glycyrrhizin of proliferation and IL-2 production of murine thymocytes.

The action of glycyrrhizin (GL) modulating the proliferation and IL-2 production of murine thymocytes in response to anti-CD3 and concanavalin A was studied. Different from the previously reported GL effect of accelerating both IL-2 production and proliferation of mature T lymphocytes, GL displayed a dissociated action on immature thymocytes promoting IL-2 production/IL-2 receptor expression but inhibiting cell growth. Hydrocortisone-resistant mature thymocytes behaved like peripheral T lymphocytes, demonstrating the dependency of the GL action on cell maturation stage. GL-mediated growth inhibition of thymocytes was not due the cytotoxic action of GL that induces cell death or DNA fragmentation. In parallel to these dissociated actions, GL promoted the tyrosine phosphorylation of p56 but suppressed the phosphorylation of p40 induced by anti-CD3. Moreover, GL and anti-CD3 showed a combination effect suppressing the transcription of c-fos, which was promoted by anti-CD3 alone or GL alone. It is suggested that whereas mature and immature T cells share a common signal pathway for IL-2 production augmented by the action of GL, they have signaling steps for DNA synthesis which are under different mechanisms receiving the modulation effects of GL in opposite directions.

Animals↗
PubMed1995

Direct evidence of involvement of glycosylphosphatidylinositol-anchored proteins in the heavy metal-mediated signal delivery into T lymphocytes.

The biological significance of the action of glycosylphosphatidylinositol (GPI)-anchored proteins in cell physiology and pathology when stimulated with their natural agonists is not known. Here we provide evidence that GPI-anchored proteins play a crucial role in the recently defined heavy metal (HgCl2)-triggered signal delivery to T lymphocytes. Thiol-reactive HgCl2, a multi-potent crosslinker of cell membrane proteins, induced heavy aggregation of Thy-1, a representative GPI-anchored protein, on murine thymocytes, and delivered a signal to induce heavy tyrosine phosphorylation of cellular proteins. This rather unusual signal delivery by HgCl2 is diminished by the pre-treatment of cells with phosphatidylinositol-specific phospholipase C, which partially cleaved GPI-anchored proteins from the cell surface. Direct evidence for the involvement of GPI or GPI-anchored proteins in the HgCl2-mediated signaling is provided by the loss of signaling in a mutant thymoma cell line defective in the phosphatidylinositol glycan-class A gene (PIG-A), and its restoration in a transfectant with PIG-A.

Animals↗
PubMed1995

A murine Thy-1.2 reporter vector containing a SV40 origin for rapid cloning and analysis of eukaryotic promoters.

A new vector, pATO, was constructed for rapid cloning and analysis of eukaryotic promoters. When a recombinant pATO, carrying a promoter sequence in its multiple cloning site, was introduced into COS cells, Thy-1.2 protein was produced on the cell surface, and was easily identified by an fluorescein-conjugated anti-Thy-1.2 antibody. The intensity of the fluorescence reflected the strength of the inserted promoter. Since pATO could replicate efficiently in COS cells, the recombinant plasmids recovered from a single COS cell were sufficient to transform Escherichia coli cells. This plasmid is applicable for the rapid and labor saving cloning of promoter elements.

Animals↗
PubMed1995

Elucidation of the protein kinase C-dependent apoptosis pathway in distinct subsets of T lymphocytes in MRL-lpr/lpr mice.

MRL-lpr mice are severely impaired in the Fas pathway of apoptosis induction. We here evaluate another pathway of apoptosis induction in MRL-lpr mice which is protein kinase C (PKC) dependent. Despite the defect of the Fas pathway, apoptosis developed during culture in vitro in splenic T lymphocytes from MRL-lpr mice more extensively than in T lymphocytes from MRL-(+/+) mice. Apoptosis induction in the former cells was then found to be greatly promoted by PKC inhibitor H-7, and partially prevented by PKC activator phorbol 12-myristate 13-acetate (PMA). High sensitivity to H-7, but not to PKA inhibitor HA 1004, of these cells for apoptosis induction was confirmed by detailed time course and dose-dependency experiments of the drug effect. Population analysis showed that both CD4+ T lymphocytes and CD8+ T lymphocytes from MRL-lpr mice were highly sensitive to H-7, whereas CD8+ T lymphocytes, but not CD4+ T lymphocytes, from MRL-(+/+) mice were susceptible to the reagent. Interestingly, B220+ Thy-1+ CD4-CD8- T lymphocytes from MRL-lpr mice were most sensitive to H-7 for apoptosis induction. Correspondingly, the membrane-translocated activated PKC-alpha level in splenic T lymphocytes from MRL-lpr was more extensively up-regulated by PMA than in splenic T lymphocytes from MRL-(+/+). These results suggest that some signal consistently activates PKC in MRL-lpr T lymphocytes, and this event is needed for survival of these cells. On the other hand, CD4+ CD8+ thymocytes were deleted by apoptosis in culture with PMA, whether these thymocytes were from MRL-lpr mice or MRL-(+/+) mice. This finding suggested that the apoptosis induction pathway linked to PKC activation is intact in CD4+ CD8+ thymocytes from the Fas-defective MRL-lpr mice. We conclude from these results that the PKC-dependent signal pathways for either cell death or cell activation are intact or even accelerated in lpr mice, which could both compensate for the loss of the Fas pathway and promote the generation of autoreactive T lymphocytes.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1995

Evidence of redox-linked signaling for producing a giant signal complex.

Previously we showed that a thiol-reactive heavy metal, HgCl2, crosslinked multiple cell surface receptors through a ligand-independent pathway, which produced massive aggregates of phosphotyrosine (PTYR)-containing proteins beneath plasma membrane [Nakashima et al. (1994): J Immunol 152: 1064-1071]. In this study we characterized these unique aggregates at the molecular level. The lysates in Brij 96 of thymocytes treated with HgCl2 were separated into the supernatant and pellet fractions by simple centrifugation. Selected PTYR-containing proteins and p56lck appeared in the pellet fraction as quickly as 5 s after exposure to HgCl2, and were further increased in amount by 5 min. Although the mechanism of triggering these events was redox-linked, the majority of proteins in the Brij 96-insoluble aggregates were dissociated in SDS-PAGE under nonreducing condition. This suggested that PTYR-containing proteins and p56lck themselves do not form dimer or polymer directly by thiol-mediated bond. The pellet fraction was further found to include some other signal delivery elements, such as GTPase activating protein, phosphatidylinositol 3 kinase, and mitogen-activated protein kinase. Finally, all of these signal elements and selected PTYR-containing proteins were collected in the same fraction by the sucrose density gradient centrifugation. These results suggest a unique redox-linked pathway of formation of a giant signal complex.

Animals↗
PubMed1995

Multiphasic modulation of signal transduction into T lymphocytes by monoiodoacetic acid as a sulfhydryl reagent.

Actions of monoiodoacetic acid (MIA) as a sulfhydryl reagent on the different stages of the T cell receptor (TCR)-mediated signal transduction were examined. MIA (1 mM) prevented anti-TCR (CD3) monoclonal antibody (mAb)-induced energy-dependent receptor capping but at the same time promoted the anti-CD3 mAb/mitogen-induced tyrosine phosphorylation of the T cell activation-linked cellular proteins of 120, 80, 70, 56, and 40 kDa. Relatively low concentration (0.01 mM) of MIA further promoted anti-CD3 mAb-induced transcription of c-fos, production of IL-2, and cell surface expression of IL-2 receptors. The MIA-promoted TCR-mediated IL-2 production actually required signal transduction that could be inhibited by cyclosporin A, genistein, or H-7. In contrast, the same concentration of MIA as promoted the signal transduction for cell activation severely inhibited the anti-CD3 mAb-triggered signal delivery for cell proliferation, selectively at its early stage. We conclude from these results that MIA differentially affects various steps of signaling into T lymphocytes, suggesting that there exist multiple sites of MIA-sensitive or redox-linked control in the signal cascade.

Animals↗
PubMed1995

Basic fibroblast growth factor-heparan sulphate complex in the human dialysis-related amyloidosis.

A major constituent of the amyloid fibrils in dialysis-related amyloidosis is beta 2-microglobulin (beta 2-MG). Heparan sulphates (HS) co-localize with the amyloid fibrils and monocytes/macrophages are commonly found around amyloid deposits, but the role of HS in amyloidogenesis is not yet defined. HS have variable saccharide sequences and can interact specifically with basic fibroblast growth factor (bFGF), a potent chemotactic factor for the monocyte/macrophage. The present investigation was undertaken to look for a functional link between co-localized HS and the pathogenesis of dialysis-related amyloidosis. Using amyloid-enriched ligament, immunohistochemical localization was tested for beta 2-MG, endogenous bFGF, and bFGF-binding portions of HS. For the detection of bFGF-binding portions of HS, the ligament sections were incubated with exogenous bFGF and then with anti-bFGF antibody. The specificity of the interaction between bFGF and HS was established by confirming a concomitant loss of immunoreactivity during selective removal of HS with heparitinase. beta 2-MG, endogenous bFGF, and bFGF-binding portions of HS were detected between bundles of collagen. Endogenous bFGF and bFGF-binding portions of HS were not detected in more advanced amyloid lesions, whereas beta 2-MG and other portions of HS were detected. We propose that beta 2-MG, endogenous bFGF, and bFGF-binding portions of HS form a complex and localize in the early amyloid lesions of dialysis-related amyloidosis.

Amyloidosis↗
PubMed1995

Cell type-oriented differential modulatory actions of saikosaponin-d on growth responses and DNA fragmentation of lymphocytes triggered by receptor-mediated and receptor-bypassed pathways.

We examined the immunoregulatory action of saikosaponin-d (SSd), which was isolated from the root of Bupleurum talcatum L. and had a steroid-like structure, on murine thymocytes, and compared the action with that on spleen cells. Constitutive DNA synthesis or the growth response stimulated with anti-CD3mAb of thymocytes were down-regulated by 3 micrograms/ml SSd, whereas with spleen cells these were up-regulated by the same concentration of SSd. On the other hand, 3 micrograms/ml of SSd greatly up-regulated the growth response and interleukin 2 (IL-2)/interleukin 4 (IL-4) production induced through a receptor-bypassed pathway by calcium ionophore A23187 plus phorbol 12-myristate 13-acetate (PMA) in thymocytes, whereas it only slightly up-regulated them in spleen cells. Moreover, the same concentration of SSd inhibited DNA fragmentation in thymocytes induced by A23187 or PMA. These results suggest a unique cell type-dependent immuno-modulatory action of SSd.

Animals↗
PubMed1995

Oncogene-linked in situ immunotherapy of pre-B lymphoma arising in E mu/ret transgenic mice.

We attempted to induce anti-tumour immunity for rejecting pre-B lymphoma derived from E mu/ret transgenic mice (TGM). We established pre-B-lymphoma cell lines of C57BL/6 x Balb/c background (H-2b/d) into which H-2k alloantigen and C3H background were introduced (retL1-6 and retL6-6), and we inoculated BCF1 mice with these immunising tumour cells. After these tumours were rejected by alloantigen (H-2k/C3H background)-specific effector cells, the mice were challenged with the pre-B-lymphoma cell line derived from the original E mu/ret TGM (ret0-2). All non-immunised control mice died within 80 days, whereas half the immunised mice survived for over 300 days. The immunity was also effective against primary pre-B-lymphoma cells from E mu/ret TGM and the ret-driven melanoma cell line (MEL-ret), but not against the pre-B-lymphoma cell line from E mu/myc TGM. This immunity was at least in part mediated by cell-mediated cytotoxicity that was specific to the ret oncogene product or ret-regulated antigen. Next we immunised E mu/ret TGM by inoculating them with retL6-6 cells once every 2 weeks beginning at the age of 1 month. Interestingly, this immunisation enabled the TGM to survive longer than the non-immunised control group (P < 0.05). Moreover, 2 of 11 transgenic mice receiving such immunisation were free from both macroscopic and microscopic tumours at the time when all of the 12 non-immunised control TGM had died from their tumour. This provides a new model for oncogene-linked immunotherapy research.

Animals↗
PubMed1995

Reinnervation of peripheral nerve segments implanted into the hemisected spinal cord estimated by transgenic mice.

We investigated how far Schwann cells, which are the peripheral nerve elements supporting axonal regrowth, penetrate into the hemisected recipient spinal cord. C57BL/6 mice, which carry carcinoembryonic antigen as transgene, were used for transplantation study. These CEA transgenic mice were syngenic to C57BL/6 mice except for the expression of human CEA DNA. In the syngenic transplantation study, C57BL/6 mice were transplanted with the sciatic nerve of CEA-transgenic mice to the hemisected spinal cord. Schwann cell migration into the recipient spinal cord was detected by the PCR method. Transplanted Schwann cells migrated into the recipient spinal cord both rostrally and caudally at a distance of 2 mm from the graft-host interface until 21 days after transplantation. At 28 days after transplantation, the Schwann cells migrated rostrally at a distance of 2 mm and caudally at a distance of 4 mm. C57BL/6-CEA sciatic nerve was transplanted to BALB/C mice as the allogenic transplant. CEA DNA was detected until 14 days after transplantation, but disappeared at 21 days. In addition, C57BL/6-CEA sciatic nerves were transplanted into Wistar rats to study xenogenic transplantation. The CEA band disappeared at 10 days after transplantation. In conclusion, by using CEA transgenic mice and the PCR method, we could evaluate the mobility of Schwann cells which are thought to play an important role in axonal regeneration.

Animals↗
PubMed1995

Effect of calcium antagonist, nicardipine, on cerebral blood flow in postasphyxial newborn piglets.

An experiment was carried out in nine piglets within 24 h after birth (control group: four, nicardipine group: five) for the purpose of evaluating the effects of a calcium antagonist, nicardipine, on cerebral blood flow changes induced by asphyxia neonatorum. Under respiratory control with a mechanical ventilator, the animals were exposed to hypoxia. The inspiratory oxygen level was lowered at 15 min intervals from 0.08 to 0.06 and then to 0.05. When bradycardia (heart rate; 60/min or less) was observed, 100% oxygen, adrenaline, and sodium bicarbonate were administered for resuscitation. Nicardipine was administered at a dosage of 10 micrograms/kg via bolus injection 30 min after the resuscitation. It was administered thereafter at a rate of 10 micrograms/kg per h. The cerebral blood flow was measured using a laser Doppler velocimeter. The cerebral blood flow, electroencephalograph (EEG), blood pressure, and heart rate were continuously measured for 120 min after the resuscitation. In the control group, the mean arterial pressure 35 min after the resuscitation was 60 mmHg or more. However, the cerebral blood flow was lower than the prehypoxia value in the animals with a mean arterial pressure of 75 mmHg or less. In the nicardipine group, the mean arterial pressure was lower, but the cerebral blood flow was higher than the prehypoxia value and cerebral ischemia was not induced. The mean arterial pressure 120 min after the resuscitation was 72.0 +/- 8.2 mmHg in the control group, while it was 56.7 +/- 7.5 mmHg in the nicardipine group. It was significantly lower in the latter.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Hepatitis C virus infection and genotypes in Japanese hemophiliacs.

Liver function and antibodies to hepatitis C virus and to human immunodeficiency virus-1 were examined in 195 Japanese patients with hemophilia. One hundred and seventy-three were positive for antibody to HCV and 61 for antibody to human immunodeficiency virus-1. In 63 patients, we examined HCV genotypes according to the double polymerase chain reaction method. Forty cases (63%) were infected with hepatitis C virus with a single genotype, including type 1a in five, type 1b in 21, type 2a in seven and type 2b in seven; 16 (25%) were infected with double genotypes, including types 1a + 1b in 14, types 1b + 2a in one and types 1b+2b in one; and four (6%) were infected with triple genotypes, including types 1a + 1b + 2b in two. Genotype could not be determined in three patients by this method. In the 191 nonhemophiliac patients with chronic hepatitis C, HCV genotyping was as follows: type 1a in 0, type 1b in 121, type 2a in 40 and type 2b in 10 of 171 cases (89.5%) with single infection and types 1b + 2a in five and types 2a + 2b in one of six (5.5%) with double infection. In the remaining 14 patients, genotype could not be determined. Frequent transfusion of domestic and/or imported coagulation factor concentrates probably caused the high incidence of HCV infection with rare or mixed genotypes in Japanese hemophiliacs.

Adolescent↗
PubMed1995

Promotion of cytotoxic T-cell generation in mixed leukocyte culture by phosphatidylinositol-specific phospholipase C from Bacillus thuringiensis.

Phosphatidylinositol-specific phospholipase C (PIPLC) from Bacillus thuringiensis, which cleaves phosphatidylinositol or glycosylphosphatidylinositol on the external cell surface to generate a second messenger for intracellular signal transduction (S. Rahman et al., FEBS Lett. 303:193-196, 1992), was found to preferentially promote the generation of alloantigen-specific cytotoxic T lymphocytes in mixed leukocyte culture. PIPLC affected an early stage of cytotoxic T-lymphocyte activation in culture, and there was no evidence of any soluble cellular mediators of this PIPLC action. PIPLC neither enhanced overall cell proliferation nor noticeably promoted interleukin-2 and -4 production in mixed leukocyte culture. The relative population size of Ly-2+ T cells was increased, however, in a late mixed leukocyte culture with PIPLC. In addition, PIPLC enhanced an anti-CD3 monoclonal antibody-induced early increase in [Ca2+]i. These results suggest a new parasite (bacterium)-oriented mechanism for enhancing antigen-driven host cytotoxic T-lymphocyte immunity which does not include promotion of interleukin-2 production.

Animals↗
PubMed1995

Enhancement of nitric oxide production from activated macrophages by a purified form of ginsenoside (Rg1).

We studied the actions of purified ginsenosides Rg1 and Rb1 on nitric oxide production from macrophages and a macrophage cell line RAW264-7. Although neither Rg1 nor Rb1 induced nitric oxide from resting macrophages, Rg1 enhanced the production of nitric oxide from IFN-gamma activated-macrophages or RAW cells. Rg1 also enhanced the production of nitric oxide from macrophages cocultured with nonadherent spleen cells stimulated by conA, LPS or anti-CD3. Rb1, however, did not significantly enhance nitric oxide production from stimulated macrophages or RAW cells. Rg1 enhanced the tumor cell killing by nitric oxide produced from IFN-gamma-activated macrophages.

Animals↗
PubMed1995

Oxidation of ethylene glycol and glycolic acid by glycerol oxidase.

A glycerol oxidase from Aspergillus japonicus oxidized ethylene glycol to glyoxal by the same reaction pathway as alcohol oxidases from methanol yeast. The optimum pH and temperature for the oxidation of ethylene glycol were around 7.0 and 40 degrees C, respectively. Those of glycolaldehyde were similar to those of ethylene glycol. The apparent Kms for ethylene glycol and glycolaldehyde were 195 and 48.8 mM, respectively. The maximum velocities for ethylene glycol and glycolaldehyde were 89.1 and 62.2 mumol/min/mg of protein, respectively. Glycerol oxidase also oxidized glycolic acid, which is not oxidized by the alcohol oxidases, to glyoxylic acid like glycolate oxidases from green plants, and the apparent Km and Vmax for glycolic acid were 114 mM and 2.68 mumol/min/mg of protein, respectively. The glycerol oxidase was applicable to the production of glyoxal and glyoxylic acid.

Ethylene Glycol↗
PubMed1995

The role of a complement regulatory protein in rat mesangial glomerulonephritis.

The host cells are protected from the indiscriminate attack of homologous complement by the membrane-associated complement regulatory proteins. A mouse monoclonal antibody (mAb) 512 (immunoglobulin G1 subclass) has recently been described that recognizes and inhibits the function of a rat complement regulatory protein, a rat homologue of mouse Crry/p65. The aim of this work is to assess the role of a complement regulatory protein (512Ag) recognized by mAb 512 in the complement-dependent glomerular injury induced by mAb OX7 against rat Thy-1.1. For the induction of mesangial injury, the left kidney of a rat was perfused with a combination of OX7 and 512 and the perfusate was discarded from the renal vein (Group I). After the renal artery and vein were restored, the left kidney was connected to the systemic circulation. Rats were euthanized 3 h, 2 days, and 14 days later. Rats perfused either with OX7 (Group II) or with 512 (Group III) or with vehicle only (Group IV) were used as controls. At 3 h, rats of Group I showed more prominent cellular infiltration and mesangial lysis and more C3 deposition in the glomeruli than rats of Group II. Rats of Groups III and IV showed no significant changes. At Day 2, there was still significant mesangial lysis and leukocyte infiltration in Group I rats, whereas rats in other groups showed an almost normal appearance. Glomerular injury in Group I rats returned to normal by Day 14.

Animals↗