Biomedical subjects

M Sakurai

Publications and source records attributed to M Sakurai.

At least 235 records · Page 13Linked to original sources

PubMed1997

mRNA expression of Fas receptor (CD95)-associated proteins (Fas-associated phosphatase-1/FAP-1, Fas-associating protein with death domain/FADD, and receptor-interacting protein/RIP) in human leukaemia/lymphoma cell lines.

mRNA expression of Fas (CD95)-associated proteins [Fas-associating protein with death domain (FADD), receptor-interacting protein (RIP), and Fas-associated phosphatase-1 (FAP-1)] has been investigated in 26 Fas-positive human leukaemia/lymphoma cell lines. Reverse transcriptase-polymerase chain reaction analysis revealed that FADD and RIP mRNA were invariably expressed in both Fas-sensitive and Fas-insensitive cell lines. However, FAP-1 mRNA was detected in only 11 of 26 cell lines. Interestingly 7/14 cell lines in the Fas-sensitive group were positive for FAP-1 mRNA expression. 8/12 cell lines in the Fas-refractory group did not express FAP-1 mRNA, but half of these cell lines were susceptible to tumour necrosis factor alpha-induced growth inhibition. These findings suggest that the presence or absence of FAP-1 mRNA expression did not always correlate with relative sensitivity of Fas-mediated growth inhibition. Furthermore, it is assumed that leukaemia/lymphoma cells could possess structural or functional defects of Fas or Fas-associated proteins resulting in the failure to trigger apoptotic cell death.

Adaptor Proteins, Signal Transducing↗

PubMed1997

FK506 inhibits anti-IgM antibody-induced apoptosis and 17 kD endonuclease activity in the human B-cell line, MBC-1, established from Burkitt's lymphoma.

The endonuclease which causes antibody-induced apoptotic cell death in B cells is not completely understood. We previously established a B-cell line (MBC-1) from a patient with Burkitt's lymphoma at the leukaemic stage which demonstrated the typical morphology and internucleosomal DNA fragmentation of apoptotic cell death when treated with anti-IgM antibody. FK506, an immunosuppressive agent and calcineurin inhibitor, partially rescued the anti-IgM antibody-induced cell death in these MBC-1 cells. DNA SDS-PAGE nuclease activity assay demonstrated that a 17 kD protein exhibited endonuclease activity. Active gel assay showed nuclease activity in the cellular nuclear extract not treated with anti-IgM antibody. This nuclease activity was inhibited by FK506 at concentrations of 10-200 ng/ml in the active gel assay. These results raise the possibility that the 17 kD endonuclease is one of the nuclear members of the immunophilin family, which may function as an endogenous endonuclease in MBC-1 cells.

Apoptosis↗

PubMed1997

Fas/APO-1 (CD95)-mediated cytotoxicity is responsible for the apoptotic cell death of leukaemic cells induced by interleukin-2-activated T cells.

Apoptotic cell death is induced by the cross-linking of Fas/APO-1 receptor (CD95) in acute myelogenous leukaemia (AML) cells. Since CD95 ligand (CD95L) is expressed on interleukin-2 (IL-2)-activated T cells, we investigated the involvement of CD95-CD95L pathway in T cell-mediated cytotoxicity against AML cells. Activated CD8+ T cells could efficiently kill a parental CD95-sensitive AML cell line, MML-1 and, to a lesser extent, a CD95-resistant clone, MML-1R. Neither MML-1 nor MML-1R cells were killed by activated CD4+ T cells. The blocking monoclonal antibody (MoAb) against CD95, ZB4, caused a significant inhibition of T-cell-mediated cytotoxicity against MML-1 cells but not against MML-1R cells. Interestingly, MML-1 cells underwent the classic nuclear morphologic changes and DNA fragmentation characteristic of apoptosis when cultured with activated T cells. Enumeration of apoptotic and necrotic nuclei showed that both apoptosis and necrosis were induced in MML-1 cells, whereas necrosis was exclusively observed in MML-1R cells. Apoptosis of MML-1 cells was completely blocked in the presence of ZB4 MoAb. Similarly, blocking by ZB4 MoAb significantly inhibited T-cell-mediated lysis of fresh AML cells in a CD95-sensitive group, but not in a CD95-refractory group. In addition CD8+ T cells expressed CD95L mRNA more abundantly than CD4+ T cells upon activation by IL-2. These findings suggest that T-cell-mediated cytotoxicity against AML cells requires participation of CD95-CD95L pathway for cytotoxic signal transduction leading to target apoptosis.

Apoptosis↗

PubMed1997

Measles virus induces apoptotic cell death in lymphocytes activated with phorbol 12-myristate 13-acetate (PMA) plus calcium ionophore.

Peripheral blood mononuclear cells (PBMC) and T lymphocytes were infected with measles virus (MV) and cultured with a protein kinase C (PKC) activator, PMA and a calcium ionophore, ionomycin. After stimulation, cell viability and incorporation of 5-bromo-2'- deoxyuridine (BrdU) were decreased in MV-infected cells compared with mock-infected cells. DNA content analysis and terminal deoxytransferase (TdT)-mediated dUTP nick end labelling demonstrated that the hypodiploid fraction and DNA fragmentation were increased in MV-infected, T lymphocytes activated with PMA plus ionomycin. These data suggest that MV induces apoptotic cell death in cells activated by PMA plus ionomycin. In contrast to stimulation with PMA plus ionomycin, mitogenic stimulation with phytohaemagglutinin (PHA) did not induce apoptotic cell death in MV-infected cells, although cell proliferation was suppressed. Apoptosis induced in stimulated, MV-infected cells may be one mechanism of immunosuppression.

Adult↗

PubMed1997

Increased natural killer resistance to cyclosporine A by continuous doses of dexamethasone in rats.

There is a controversy on the effects of physiological levels of glucocorticoids on natural killer (NK) cytotoxity. Therefore, the effects of exogenously administered dexamethasone on NK cytotoxity in 8-week-old male, Fischer 344 rats were studied. We suppose that the reason for the controversy is insufficient sensitivity of the ordinal radioactive chromium-release assay for normal healthy subjects or animals. Therefore, we developed a new index, a resistance to artificial immunosuppressor, cyclosporine A (CsA) using rat NK activity as an indicator, and named this index, increased resistance to immunosuppressor (IRIS). After some basic, characterizing studies, authors confirmed the fact that continuous doses of dexamethasone (DEX) attenuated NK suppression of CsA. In protocol 4, 18 rats were randomly divided into three groups: the first (DEX + CsA) was injected for 5 days with 0.1 mg DEX/kg/day and a single dose of CsA on the final day, intraperitoneally; the second (SAL + CsA) was treated with an equal volume of saline and CsA; the third (DEX + SAL) was treated with DEX but not CsA. The IRIS in NK activity was increased significantly (P < 0.01) with 5 days injection of DEX. These results demonstrated that physiological, and continuous dosage of glucocorticoids stimulated IRIS in NK activity in rats, and this suggests that appropriate stimuli through the hypothalamic-adrenal axis might be acting, at least, as a defence against immune collapses or dysfunctions.

Animals↗

PubMed1997

No influence of a single bout of exercise on urinary excretion of 8-hydroxy-deoxyguanosine in humans.

We investigated the effect of a single bout of intensive exercise on the excretion of 8-hydroxy-deoxyguanosine in the 24 h urine from healthy non-smokers. We studied three exercise tests in Experiment 1; which consisted of incremental exercise to exhaustion on a treadmill in eleven male long distance runners. Experiment 2; which comprised incremental exercise until reaching exhaustion on a bicycle ergometer in six male untrained subjects. Experiment 3; which consisted of a 20 km run by eleven male long distance runners. No differences in the urinary 8-hydroxy-deoxyguanosine excretion were observed from days 1 to 3 after each respective exercise regimen. However, significant increases in the plasma creatine kinase activity were observed at 24 h or 48 h after exercise, except for Experiment 2. Our results thus suggest that the oxidative stress during a single bout of intensive exercise does not result in an accumulation of oxidative DNA damage.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed1997

Herpes simplex virus type 1 induces apoptosis in peripheral blood T lymphocytes.

Apoptosis in peripheral blood T lymphocytes induced by herpes simplex virus type 1 (HSV-1) was investigated by use of DNA content analysis and the terminal deoxytransferase-mediated dUTP nick end-labeling method. The hypodiploid fraction in the cell cycle and DNA fragmentation were both increased in HSV-1-infected T lymphocytes compared with that in mock-infected T lymphocytes on stimulation with phytohemagglutinin (PHA). There was no difference in the hypodiploid fraction and DNA fragmentation between HSV-1-infected T lymphocytes and mock-infected cells cultured without PHA. HSV-1 enhanced apoptosis in CD4 and HLA-DR-positive T lymphocytes, but not in CD8 lymphocytes, when stimulated with PHA. These results demonstrate that HSV-1 infection enhances apoptosis in activated T lymphocytes, particularly CD4 and HLA-DR-positive T lymphocytes. bcl-2 expression was unchanged in mock- and HSV-1-infected CD4 and CD8 lymphocytes cultured with or without PHA, indicating that bcl-2 does not contribute to HSV-1-induced apoptotic cell death. Apoptosis in CD4 helper T lymphocytes may account for immunosuppression and lymphocytopenia following HSV-1 infection.

Apoptosis↗

PubMed1997

Apoptosis of cord blood T lymphocytes by herpes simplex virus type 1.

We investigated apoptosis induced by herpes simplex virus type 1 (HSV-1) in cord blood T lymphocytes by using agarose gel electrophoresis, DNA content analysis and the terminal deoxytransferase (TdT)-mediated dUTP nick end-labelling (TUNEL) method. DNA fragmentation and the hypodiploid fraction in the cell cycle were both increased in HSV-1-infected CD4 and CD8 lymphocytes stimulated with phytohaemagglutinin (PHA) compared to mock-infected lymphocytes. The percentage of cells in the S phase was decreased in HSV-1-infected CD4 and CD8 lymphocytes. HSV-1 antigen, glycoprotein D (gD) and regulatory protein ICP27 were detected in 8-18% of the hypodiploid fraction of PHA-stimulated, HSV-1-infected lymphocytes. Apoptosis was induced not only in HSV-1 antigen-expressing cells but also in cells not expressing detectable viral proteins. Addition of anti-Fas antibody, anti-Fas-ligand antibody or a mixture of both had no effect on HSV-1-induced apoptosis, indicating that the Fas-Fas-ligand pathway did not contribute to HSV-1-induced apoptosis.

Antigens, Viral↗

PubMed1997

Early hepatocellular carcinoma macroscopically resembling adenomatous hyperplasia: pathological resemblance to carcinoma-in-situ.

The pathological features of 11 nodules of early hepatocellular carcinoma (EHCC) were studied. Their macroscopic features resembled those of adenomatous hyperplasia and differed from those of advanced hepatocellular carcinomas (AHCC). The EHCC extended along the hepatic lobular structure and lacked expansive growth. The endothelial cells in the sinusoids of EHCC did not react to Ulex europaeus agglutinin 1 (UEA1) like adenomatous hyperplasia or other liver parenchyma, whereas the endothelial cells in the AHCC did react to UEA1. Immunohistochemically, CD68-positive Kupffer cells were noted in the sinusoids of EHCC, whereas in the AHCC Kupffer cells were not seen. Tumor emboli in the portal vein and intrahepatic metastases were not identified in EHCC, which seemed to be carcinoma-in-situ or a microinvasive stage of hepatocarcinogenesis.

Adenoma↗

PubMed1997

Analysis of hyperplastic foci in livers with hepatocellular carcinomas by flow cytometry and AgNOR staining.

The phase S ratio in cell cycles were analyzed in livers with hyperplastic foci (HPF) and in livers without HPF by nuclear DNA determinations using flow cytometry, and by staining with argyrophilic proteins of the nucleolar organizer region (AgNOR). Flow cytometric analysis was done on 50 fresh frozen specimens of livers resected from 50 patients with hepatocellular carcinoma (HCC). Paraffin sections from the same patients were analyzed using AgNOR staining. There were 25 cases each with and without HPF. We examined the stage of fibrosis and the grade of inflammatory activity according to the modified Scheuer and Desmet scale. The incidence of HCC recurrence among these patients was also studied. The average phase S ratio of the livers of the patients with HPF was 6.5 +/- 3.2%, and that of the livers of the patients without HPF was 4.0 +/- 2.5%. The ratio differed significantly between the two groups (P < 0.01). The average AgNOR score for HPF lesions of the HPF-positive cases was 1.60 +/- 0.34, that for non-HPF lesions in the HPF-positive cases was 1.29 +/- 0.12, and that for the HPF-negative cases was 1.19 +/- 0.14. Significant differences were found between the average AgNOR scores for HPF lesions of the HPF-positive cases and the non-HPF lesions of the HPF-positive cases (P < 0.01), as well as between the non-HPF lesions in the HPF-positive cases and the HPF-negative cases (P < 0.05). Severe fibrosis (stage 3) and cirrhosis (stage 4) were found in 76% of HPF-positive cases and 48% of HPF-negative cases. The livers of HPF-positive patients were significantly more cirrhotic than those of HPF-negative patients (P < 0.05). The association between HPF and the inflammatory grade was not significant (P > 0.05). The incidence of HCC recurrence among HPF-positive cases was significantly higher than that among the HPF-negative cases (P < 0.05). The average phase S ratio of the recurrent HPF-positive patients was 7.48 +/- 3.48%, significantly higher than that of HPF negative cases (5.57 +/- 3.06%, P < 0.05). Hyperplastic foci of the liver was shown to be a highly proliferative lesion. The proliferative activity of the non-HPF lesions in the HPF-positive patients was also higher than that of the HPF-negative patients. Hyperplastic foci tended to be present in cirrhotic livers, but it was not associated with the grade of inflammatory activity of the liver. Hyperplastic foci may represent an important predictor of recurrence after hepatic resection.

Adult↗

PubMed1997

2',5'-Oligoadenylate synthetase activity and T cell subset in the cerebrospinal fluid and peripheral blood of aseptic meningitis.

2',5'-oligoadenylate synthetase activity, which is assumed to be induced by interferon, is reported to be one of the useful markers reflecting interferon activity. The enzyme activity of patients with aseptic meningitis and febrile convulsion were compared in order to evaluate interferon activity as one of the local immuno-defense mechanisms of aseptic meningitis. The surface antigen of mononuclear cells in cerebrospinal fluid and peripheral blood of some patients with aseptic meningitis was also measured. The enzyme activity of patients with aseptic meningitis was 191.4 pmol/dL in the cerebrospinal fluid and 395.8 pmol/dL in the serum during the acute phase, while that of patients with febrile convulsion was 45.2 pmol/dL in the cerebrospinal fluid and 326.0 pmol/dL in the serum. The enzyme activity of the former patients significantly decreased during the recovery phase in both the cerebrospinal fluid and serum. CD3 positive cells in the peripheral blood were 56.3% of the total mononuclear cells during the acute phase and 65.2% during the recovery phase, whereas in the cerebrospinal fluid mononuclear cells, they were 87.1 and 85.5%, respectively. During the acute phase, CD4 positive cells were the predominant T lymphocyte subset in the cerebrospinal fluid cells, while CD8 positive cells were predominant during the recovery phase. The relative proportions of CD4 positive and CD8 positive cells during the acute and recovery phase in the cerebrospinal fluid mononuclear cells were quite high compared to the recovery phase, although that ratio of peripheral blood mononuclear cells was not changed throughout the course. It was concluded that T lymphocytes and increased 2',5'-oligoadenylate synthetase activity in the cerebrospinal fluid may be one of the important components in the local inflammatory process independent of the systemic host defense mechanism in aseptic meningitis.

2',5'-Oligoadenylate Synthetase↗

PubMed1997

Epstein-Barr virus infection, Hodgkin's disease, non-Hodgkin's lymphoma, and reactive follicular hyperplasia in Japanese children: evaluation of paraffin-embedded specimens using polymerase chain reaction and immunohistochemistry.

Epstein-Barr virus (EBV) infections are common in Japanese children, with infectious by EBV type 1. The relationships between EBV infection and lymphadenopathies in Hodgkin's disease (HD), non-Hodgkin's lymphomas (NHL), reactive follicular hyperplasia (RFH), and infectious mononucleosis (IM) in 37 Japanese children were evaluated. Formalin-fixed, paraffin-embedded lymph node specimens that were obtained at surgical resection or biopsy were evaluated for the presence of EBV DNA and the latent membrane protein-1 (LMP-1) using polymerase chain reaction (PCR) and immunohistochemical staining. The PCR detected EBV DNA in nine of 13 (69.2%) patients with RFH, including a case of IM, all three (100%) patients with HD, and one of 21 (4.8%) patients with NHL. All EBV-positive samples contained EBV type 1. Reed-Sternberg's cells in HD were immunohistochemically positive for LMP-1, whereas all cases of RFH and NHL were negative for LMP-1. Results suggest that EBV infection may be related to HD. Although no proof exists that EBV infection contributes to the transformation of cells, thus causing RFH or NHL, the present authors suggest that the EBV-positive cases in Japanese children demonstrate a relationship between the clinical and histopathological features of the lymphadenopathy and EBV-type 1 infection.

Child↗

PubMed1997

A case of Epstein-Barr virus infection with exophthalmos and ocular muscle swelling.

A 14-year-old girl with Epstein-Barr virus (EBV) infection developed exophthalmos and ocular muscle swelling. The EBV genome was detected in T lymphocytes taken from the submandibular gland, temporal muscle and cervical lymph nodes. A surface marker analysis of her peripheral blood demonstrated that CD45RO-positive T lymphocytes were strongly activated. Immunosuppressive treatment, including steroid and cyclophosphamide, was effective in improving the symptoms. Immunosuppressive therapy may be included as the choice of treatment for EBV infection.

Adolescent↗

PubMed1997

Cytotoxic T-lymphocytes recognizing P-glycoprotein in murine multidrug-resistant leukemias.

A multidrug-resistant murine lymphoid leukemia P388/ADR overexpresses P-glycoprotein (P-gp), an active transporter that pumps cytotoxic drugs out of cells and a product of mdr1 gene. Cytotoxic T lymphocytes (CTL) that showed cytotoxicity against P388/ADR were generated from mixed lymphocyte tumor cell culture. CTL do not kill drugsensitive parental P388 (P388/parent) that does not express P-gp. Monoclonal antibody against P-gp inhibited cytotoxic activity. Similar results were obtained in another multidrug-resistant cell line P388/VP-16. Cytotoxic activity was mediated by Thy1+ CD4- CD8+ T-cells. When P388/ADR was treated with murine IL-4, expression of P-gp was downregulated. Monoclonal antibody against interleukin-4 (IL-4) abrogated the IL-4-induced suppression of P-gp. Cytolytic activity of CTL against IL-4-treated P388/ADR was dose dependently inhibited. These results suggest that P-gp is immunogenic and can be a target of CTL in this murine leukemia model.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1997

Effect of amino acid and glucose administration during postexercise recovery on protein kinetics in dogs.

To examine the effect of the timing of amino acids (AA) and glucose (G) administration after exercise on protein kinetics, ten dogs fitted with chronic catheters in the artery and the femoral vein ran on a treadmill for 150 min. They were intraportally infused with a solution containing AA and G either right after (E) or 2 h after (L) the exercise. The protein kinetics were estimated using the arteriovenous difference of phenylalanine (Phe) coupled with the [2H5]Phe dilution method. The net balance of Phe across the hindlimb (HL) was negative after exercise. It became positive in E within 15 min after the start of the infusion, and it remained negative in L until the infusion was initiated. The uptake of Phe by the HL during the second half of the infusion period was higher in E than in L (10.9 +/- 6.6 vs. 5.4 +/- 2.3 nmol.kg-1.min-1, P = 0.049). During the infusion, protein synthesis in the HL was higher in E than in L (29.7 +/- 9.6 vs. 22.0 +/- 10.1 nmol.kg-1.min-1, P = 0.028), whereas proteolysis was comparable (18.7 +/- 5.7 vs. 16.5 +/- 11.1 nmol.kg-1.min-1. These results suggest that the early provision of the nutrients after exercise more effectively enhances protein accretion than nutrients administered later.

Amino Acids↗

PubMed1997

IL-5 as a strong secretagogue for human eosinophils.

The ability of IL-5 to induce eosinophil degranulation was investigated. Peripheral blood eosinophils from patients with mildly allergic individuals were isolated with CD16- selection method. Eosinophils were then incubated with interleukin-5 (IL-5) (0.1-100 ng/ml) for 1-48 h and EPX in the supernatants were measured with RIA. We found that IL-5 induced significant amount of eosinophil protein X in a concentration-dependent manner at 24 h. Eosinophil viability was about 90% either in the presence or absence of IL-5 at 24 h. Eosinophils stimulated with IL-5 adhered to the plate. Anti-CD18 mAb blocked adhesion and degranulation induced by IL-5. Dexamethasone and TGFbeta significantly inhibited degranulation in a concentration-dependent manner. These results suggest that IL-5 may be a strong secretagogue for eosinophils, that adhesion via beta2 integrin is a requisite for degranulation, and that the anti-inflammatory effect of corticosteroids and TGFbeta may be exerted at least in part, through the inhibition of eosinophil degranulation.

CD18 Antigens↗

PubMed1997

In vitro and ex vivo anti-human immunodeficiency virus (HIV) activities of a new water-soluble HIV protease inhibitor, R-87366, containing (2S,3S)-3-amino-2-hydroxy-4-phenylbutanoic acid.

In a series of compounds containing (2S,3S)-3-amino-2-hydroxy-4-phenylbutanoic acid (AHPBA), a transitionstate mimetic, R-87366:(2S,3S)-3-[N-(quinoxaline-2-carbonyl)-L-asparaginyl]amino- 2-hydroxy-4-phenylbutanoyl-L-proline tert-butylamide, was found to be a potent human immunodeficiency virus protease inhibitor (Ki value was 11 nM) and anti-HIV agent (IC90 value was 0.5 microM for HIV-1IIIB acutely infected cells) with moderate water-solubility (4.2 mg/ml at 25 degrees C). The compound was also active in chronically infected Molt-4/HIV-1IIIB cells, and inhibited the proteolytic processing of p55 into p17, suggesting that its anti-HIV activity was derived from HIV protease inhibition. The compound showed more potent activity (IC90 value was 0.03-0.25 microM) against clinical isolates of HIV in 5 out of 6 patients examined with varying clinical status in an ex vivo assay. One isolate, however, from the sixth patient, was less sensitive to R-87366 (IC90 value was 0.5 microM). In experiments with this strain, R-87366 showed comparatively low efficacy in acutely infected peripheral blood mononuclear cell (PBMC). This result suggests that the diversity of sensitivity shown in the ex vivo assay could be caused by the viral property itself. As a result of the determination of nucleic acid sequences in the clinical isolates, some amino acids were found to be substituted in the protease region, in contrast to the HIV-1 clade B consensus sequence, and some of them have been reported to contribute to the susceptibility of HIV protease inhibitors.

Amino Acid Sequence↗

PubMed1997

The efficacy of radiofrequency catheter ablation for the treatment of ventricular tachycardia associated with cardiomyopathy.

We performed radiofrequency catheter ablation (RF ablation) for ventricular tachycardia (VT) in 2 patients with dilated cardiomyopathy (DCM) and 1 patient with arrhythmogenic right ventricular dysplasia (ARVD). Patient 1 had incessant VT associated with DCM. RF ablation was performed where diastolic potentials were recorded and concealed entrainment was demonstrated. VT was terminated by RF ablation. Patient 2 had drug-resistant VT associated with ARVD. RF ablation was performed where perfect pace-mapping was obtained during sinus rhythm, diastolic potentials were recorded and concealed entrainment was demonstrated. VT was terminated by RF ablation. Patient 3 had 2 morphologically distinct VTs associated with DCM. The target for RF ablation was 1 of the 2, which was a drug-resistant type. Perfect pace mapping was obtained where delayed potentials were recorded. As the current strength of pacing was reduced, the QRS complex configuration switched to the other type. This site was thought to be the common slow conduction zone for the re-entry circuit of the 2 types and RF ablation was performed at this site. In these 3 cases, VT did not recur after ablation. RF ablation is effective for the treatment of VT associated with cardiomyopathy.

Aged↗