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Biomedical subjects

G Suzuki

Publications and source records attributed to G Suzuki.

At least 91 records · Page 5Linked to original sources
PubMed1995

Impaired CD28-mediated co-stimulation in anergic T cells.

We have investigated a CD28 co-stimulation in anergic T cells in staphylococcal enterotoxin B-inoculated mice by stimulating the cells with a plate-coated anti-TCR antibody in the presence or absence of an anti-CD28 antibody. CD28 co-stimulation increased the levels of IL-2 and IL-4 mRNAs in naive CD4+V beta 8+ T cells. However, it did not increase the levels of IL-4 mRNA at all and only partially increased those of IL-2 mRNA in anergic T cells. It was demonstrated that CD28 co-stimulation was impaired so that it no longer stabilized cytokine mRNAs in anergic cells. The levels of IL-4 mRNA in response to TCR stimulation were higher in anergic T cells than those in naive T cells in spite of the defective CD28 co-stimulation in the former cells. Anergy induction and generation of a Th2-type immune response in vivo are discussed.

Animals↗
PubMed1995

Expression of IL-1 beta mRNA in mice after whole body X-irradiation.

IL-1 beta is a stimulator of hematopoietic and inflammatory systems, and also acts as a radioprotector. After whole-body exposure to sublethal doses of ionizing radiation, the IL-1 beta mRNA level in spleen cells increases for a short time prior to regeneration of the spleen. We analyzed spleen cells of C3H/He mice after whole-body irradiation with 3 Gy x-rays to determine the cause of this short-term increase in the transcription level. An increase in the level of the message in spleen cells, found by Northern blot hybridization, reached its peak 5 to 7 days after irradiation. There was a low correlation between the curves of the mRNA level and the ratio of monocyte/macrophage lineage cells; a typical source of the message. Spleen macrophages that produce a large amount of the message were found 7 days after irradiation in an in situ hybridization experiment in which heterogeneous spleen cell populations were used. In contrast, spleen cells had no detectable levels of macrophages rich in IL-1 beta mRNA before and 17 days after irradiation. Additionally, the population of message-rich cells was 9.4% of the total number of monocytes/macrophages in the spleen. These results suggest that the short-term increase in IL-1 beta mRNA is a result of the heterogeneous differentiation of a subpopulation of spleen macrophages before regeneration of the spleen.

Animals↗
PubMed1995

Tumor necrosis factor and interleukin-1 synergize with irradiation in expression of GM-CSF gene in human fibroblasts.

Tumor necrosis factor (TNF) and interleukin-1 (IL-1) improve the survival of lethally irradiated animals through production of hematopoietic growth factors. Exposure of fibroblasts to TNF (1000 U/ml) drastically increased granulocyte-macrophage colony-stimulating factor (GM-CSF) mRNA at 1 h and the level returned nearly to baseline by 24 h. Levels of GM-CSF RNA were less than basal level at 24 h after exposure to irradiation alone. In contrast, cells cultured with TNF (1 h) and then irradiated, had prominent expression of GM-CSF mRNA at 24 h. Transcriptional run-on analysis has shown that TNF stimulated the rate of GM-CSF transcription by > 10-fold in irradiated cells. Moreover, TNF stabilized GM-CSF mRNA at 24 h after irradiation; 4 increased from < 20 min in untreated cells to > 2 h in cells cultured initially with TNF and followed by irradiation. We repeated the same experiments with IL-1 and found that IL-1 had the same effects on accumulation, transcription, and stabilization of GM-CSF RNA. Our findings indicate that TNF and IL-1 synergize with irradiation in expression of GM-CSF gene in human fibroblasts; this increased expression occurs by enhancement of transcriptional rate and post-transcriptional stabilization of GM-CSF mRNA.

Cells, Cultured↗
PubMed1995

[Pediatric anesthesia and stress response].

The hyperglycemic and adrenocortical responses to upper and lower abdominal surgery were studied in four groups of children. In F group, lower abdominal surgery was performed under light general anesthesia (halothane 0.3-0.5% plus nitrous oxide and oxygen) combined with intravenous injections of fentanyl 10-13 micrograms.kg-1. In L-E group, lower abdominal surgery was performed under light general anesthesia combined with lumbar epidural anesthesia (intermittent injections of 1.0% lidocaine). In T-E group, upper abdominal surgery was performed under light general anesthesia combined with thoracic epidural anesthesia (intermittent injections of 1.0% lidocaine). In H group, lower abdominal surgery was performed under general anesthesia (halothane 1.0-1.5% plus nitrous oxide and oxygen). The hyperglycemic and adrenocortical responses were inhibited in F group, suggesting that intravenous injections of fentanyl 10-13 micrograms.kg-1 prevented the endocrine-metabolic response. On the other hand, in other three groups, those responses were not inhibited. Therefore we must consider the concentration and the volume of lidocaine in epidural groups. But general anesthesia combined with epidural anesthesia had a excellent effect on the postoperative pain management.

Abdomen↗
PubMed1995

Molecular cloning of members of the S-multigene family in self-incompatible Brassica campestris L.

We isolated 12 groups of genomic clones that contained SLG-homologous regions from a genomic library constructed from an S9 homozygote of self-incompatible Brassica campestris. Both SLG9 and SRK9 genomic clones, which are located within the self-incompatibility (S) locus, were included in these groups. The promoter regions of SLG9 and SRK9 were completely identical for at least 200 bp upstream from their respective initiation codons (ATG). The five sequence elements (boxes I to V) that are conserved in the promoters of SLG and SRK genes were also found in the SLG9 and SRK9 clones. However, one conserved element (box III) unexpectedly lacked 7 of 11 bp, although box III has been considered necessary for expression in pistil. The other ten groups of genomic clones were classified into six SRK-like groups and four SLG-like groups. These results indicate that SLG, SRK, SLG-like, and SRK-like genes form a large S-multigene family in B. campestris.

Base Sequence↗
PubMed1994

In vitro effects of OK-432 on irradiated mouse bone marrow cells.

PURPOSE: In vitro effects of OK-432 on irradiated mouse bone marrow cells are examined. METHODS AND MATERIALS: Bone marrow cells of BDF1 mouse (1 x 10(6) cells/ml) were incubated with alpha medium, 2% fetal calf serum and OK-432 in a CO2 incubator at 37 degrees C for 24, 48 and 72 h, respectively. After centrifugation, each supernatant was collected and used for conditioned medium in CFU-GM assay: Changes in CFU-GM as a function of incubation time and OK-432 dose was examined; changes of CFU-GM according to various doses of OK-432 were examined in two mouse strains, BDF1 and BALB/c mouse; changes in protective effect of OK-432 in terms of CFU-GM as a function of administration timing of OK-432 in relation to irradiation. As a radiation source, 137Cs at a dose rate of 500 cGy/min was used. RESULTS: The CFU-GM decreased with the incubation time when OK-432 was not administered, while it significantly increased with incubation time when OK-432 was added at 0.5 and 1.0 KE/ml at 48-72 h of incubation. The former showed marked increase at 48-72 h of incubation. CFU-GM of BDF1 mouse was always higher than that of BALB/c mouse for any dose of OK-432. CFU-GM per femur according to the timing of administration of OK-432 from 24 h before to 24 h after irradiation showed 10299 +/- 2300 (24 h before), 10783 +/- 2463 (3 h before), 10045 +/- 1501 (immediately after), 8504 +/- 1188 (3 h after), 4898 +/- 1212 (6 h after), 1214 +/- 736 (12 h after) and 181 +/- 113 (24 h after irradiation), respectively. CONCLUSION: OK-432 stimulates cultured mouse bone marrow cells to produce GM-CSF in vitro by direct contact action. This direct stimulating action of OK-432 on GM-CSF production of bone marrow cells can be kept from 24 h before to at least 3 h after irradiation.

Animals↗
PubMed1994

Number and location of AUUUA motifs: role in regulating transiently expressed RNAs.

Many RNAs coding for either cytokines or oncogenes are unstable and have a short half-life (t1/2). The AUUUA motif is a highly conserved sequence and is repeated three or more times in the 3' untranslated region (3'UTR) of RNAs encoding many of these short-lived cytokines and oncogenes. These sequences can confer instability. In this study, we investigated the role of number and location of AUUUA motifs in stabilization of RNA. We introduced 1xATTTA, 2xATTTA, ATTTTTTTA (second adenosine of 2xATTTA was substituted with a thymidine), 3xATTTA, 5xATTTA, 7xATTTA [AT-rich sequence from granulocyte-macrophage colony-stimulating factor [GM-CSF] gene (AT-62)], and GC-62 (GC sequences were substituted for ATTTA sequences in the 7xATTTA) into the 3'UTR of rabbit beta-globin (R beta G) gene. This construct also contained the neomycin-resistance gene. These expression vectors were transfected into human lung fibroblasts (W138), which constitutively expressed low levels of GM-CSF mRNA. Stable transfectants were selected by growth in G418. Northern blot analysis of actinomycin D-treated, stably transfected cells demonstrated that the number of AUUUA sequences correlated with rapidity of turnover of the chimeric R beta G mRNA. The rank order of stability was GC-62 = 1xATTTA = 2xATTTA (no RNA decay at 4 hours) > 3xATTTA = 5xATTTA (t1/2, 4 hours) > 7xATTTA (t1/2, 2 hours). Stability of mRNA of R beta G also was reduced (t1/2, 2 to 4 hours) when AT-62 was introduced into the second exon of R beta G gene. In these same cells, the t1/2 of GM-CSF RNA was approximately 10 to 15 minutes, suggesting that the AUUUA motifs cannot alone account for the rapid degradation of this cytokine mRNA. Phorbol diesters, including 12-0-tetradecanoyl phorbol 13-acetate (TPA), stabilize a variety of transiently expressed RNAs, including GM-CSF RNA. We found that TPA markedly increased (> 30-fold) the accumulation of GM-CSF RNA. In contrast, TPA was unable to stimulate the levels of the chimeric R beta G when either 1x, 2x, 3x, or 5xATTTA motifs were fused to 3'UTR, or when either AT-62 or GC-62 control sequences were fused to the second exon. The chimeric beta-globin construct with either AT-62 or ATTTTTTTA in the 3'UTR had only an approximately twofold to threefold increase in accumulation.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1994

Irradiation increases expression of GM-CSF in human fibroblasts by transcriptional and post-transcriptional regulation.

Fibroblasts produce a variety of cytokines including granulocyte/macrophage colony-stimulating factor (GM-CSF). GM-CSF is pivotal for proliferation and function of myeloid cells. In this report, we describe the regulation of GM-CSF gene by irradiation in human fibroblasts. We found that fibroblasts constitutively produced GM-CSF; irradiation markedly increased the production of GM-CSF. The increase in GM-CSF transcripts by irradiation was both time- and dose-dependent. Moreover, irradiation increased GM-CSF mRNA in cells with prolonged exposure to 12-O-tetradecanoyl-phorbol-13-acetate (TPA). WI38 fibroblasts constitutively produce low levels of IL-1. Induction of GM-CSF mRNA by irradiation was partially blocked by anti-IL-1 antibodies. On the other hand, inhibition of prostaglandin synthesis did not affect induction of GM-CSF RNA. Transcriptional run-on analysis showed that irradiation increased the rate of GM-CSF transcription. Stability studies of GM-CSF mRNA in these cells showed that half-life (t1/2) increased from < 20 min in unirradiated cells to > 100 min in irradiated cells. These findings suggest that the increase in GM-CSF mRNA observed after irradiation is regulated by transcriptional and post-transcriptional mechanisms. Our results indicate that induction of GM-CSF gene by irradiation requires de novo protein synthesis and increased levels of GM-CSF transcripts also occur through a pathway distinct from protein kinase C activation.

Dose-Response Relationship, Radiation↗
PubMed1994

Characterization of p59fyn-mediated signal transduction on T cell activation.

Protein tyrosine kinase p59fyn is associated with the TCR-CD3 complex and is suggested to play a role in T cell activation. To determine the molecular mechanism of p59fyn-mediated signal transduction in T cell activation, we established murine T cell hybridoma lines that expressed an elevated amount of wild-type or mutant fyns. Clones that expressed high levels of normal p59fyn and active p59fyn, encoded by wild-type and f-14 mutant fyn respectively, showed enhanced IL-2 production upon stimulation by anti-CD3 antibodies or natural antigen. On the other hand, clones that expressed kinase negative p59fyn and p59fyn with an SH2 (Src-homology 2) deletion encoded by t-1 mutant fyn showed little induction of IL-2 production upon stimulation. These data suggest that p59fyn is important in T cell signaling and that the SH2 sequence plays a critical role in the reaction. Induction of tyrosine phosphorylation of multiple proteins upon antigenic stimulation was augmented similarly in the cells that respectively expressed wild-type and f-14 mutant fyns at elevated levels. The proteins that became highly tyrosine-phosphorylated included phospholipase C (PLC-gamma 1), p95vav, ZAP-70, the MAP kinase, CD3 zeta and unidentified proteins of 120, 100 and 80 kDa. Tyrosine phosphorylation of the 120, 95 and 68 kDa proteins associated with PLC-gamma 1 was also observed in these cells upon stimulation. In contrast, only the 100 kDa protein and the MAP kinase were increasingly tyrosine phosphorylated in the antigen-stimulated cells expressing t-1 fyn. These data suggest that PLC-gamma 1, PLC-gamma 1 associated molecules, p95vav, the 80 kDa protein, ZAP-70 and the CD3 zeta chain may be substrates of p59fyn or of other tyrosine kinases regulated by p59fyn and be important in T cell signaling.

Animals↗
PubMed1994

[Perioperative management of pediatric patient with vena cava superior thrombosis complicated with nephrotic syndrome].

Nephrotic syndrome is a disease which accompanies hypoproteinemia, edema, hyperlipidemia and coagulopathy. This syndrome has also been recognized in pediatric patient. We experienced recently a case of 11-year-old girl, who had insertion of a plasma exchange catheter because of secondary hyperlipidemia due to nephrotic syndrome. She suffered soon from a severe SVC obstruction by thrombosis grown up around the catheter and an emergency thrombectomy was planned under the cardiopulmonary bypass. Renal function was maintained preoperatively, in comparison with nephrotic syndrome in adult where some problems in perioperative management, such as difficulties in tracheal intubation, choice of anesthetic drugs, blood and fluid management, monitoring without CVP and weaning from ventilator are observed. Induction was carried out carefully under spontaneous breathing and the anesthetic method we used consisted of balanced technique using N2O, O2, fentanyl and pancuronium bromide with moderate hyperventilation. Intraoperative course was uneventful and the patient was extubated on the second day after the operation without any neurological defects.

Anesthesia, Inhalation↗
PubMed1994

Radiosensitivity of CD45RO+ memory and CD45RO- naive T cells in culture.

Radiosensitivities of various human T-cell subsets were investigated by a proliferation assay and by a single-cell gel electrophoresis assay. Each T-cell subset was purified using a cell sorter and was induced to proliferate by ionomycin and interleukin 2. Unsorted T cells showed biphasic dose-survival curves, indicating the heterogeneity of T cells in terms of radiosensitivity. Purified CD4+ helper and CD8+ killer T cells showed similar biphasic dose-survival curves. Hence both T-cell subsets were composed of cells of different radiosensitivity. The T-cell subsets belonging to different activation stages such as CD45RO+ memory and CD45RO- naive T cells had different dose-survival curves. The former was more radiosensitive than the latter. The high radiosensitivity of CD45RO+ cells was also demonstrated by single-cell gel electrophoresis after irradiation. This is the first demonstration that a particular cell surface marker on T cells is correlated with greater radiosensitivity.

Antigens, CD↗
PubMed1993

Effect of human recombinant granulocyte colony-stimulating factor on induction of myeloid leukemias by X-irradiation in mice.

Hematopoietic suppression is one of the serious problems induced by whole body irradiation. Granulocyte colony-stimulating factor (G-CSF) stimulates the progenitors of granulocytes and accelerates their recovery from bone marrow suppression induced by cytotoxic chemotherapy or radiation. On the other hand, G-CSF stimulates proliferation of myeloid leukemia cells as well as normal granulocytes in vitro. We designed a method to determine if G-CSF affects the incidence of myeloid leukemias induced by irradiation and the types of leukemias induced according to the French-American-British (FAB) classification in RFM/MsNrs mice. Administration of G-CSF (2 micrograms/d for 7 days) after a single 3-Gy irradiation significantly increased the number of peripheral blood neutrophils as compared with those in control mice. Even after discontinuation of G-CSF, both the total leukocyte and neutrophil counts increased to day 10, and their levels remained elevated until day 14. The incidence of myeloid leukemia in mice exposed to a single 3-Gy irradiation was 18.6% (38 of 204), and treatment with G-CSF did not increase the incidence (15.7% [32 of 204]). In the mice with radiation-induced leukemia, those receiving G-CSF had a mean survival time of 357 days, whereas those not receiving the factor survived for 349 days. There was no significant difference of survivals between the two groups. Most of the radiation-induced leukemias in the two groups were M1 or M2, according to the FAB classification; no characteristic difference was observed among the types of leukemias. Although G-CSF stimulated the leukemia cells in vitro, G-CSF administration after irradiation did not increase the occurrence of radiation-induced myeloid leukemias. Our results show that administration of G-CSF effectively accelerates neutrophil recovery from irradiation-induced hematopoietic injury and does not enhance the induction of myeloid leukemia in RFM/MsNrs mice by irradiation.

Animals↗
PubMed1993

Effects of different doses of thiopentone on the increase in serum myoglobin induced by suxamethonium in children.

We have studied the effects of different doses of thiopentone on the increase in serum myoglobin after administration of suxamethonium during inhalation induction of anaesthesia in children. Forty-three children were anaesthetized with halothane and nitrous oxide in oxygen and allocated to four groups: group S received suxamethonium 1 mg kg-1 to facilitate intubation; group ST2 received thiopentone 2 mg kg-1 and group ST4 received thiopentone 4 mg kg-1, before administration of suxamethonium 1 mg kg-1; group N did not receive thiopentone or suxamethonium. Serum myoglobin and creatine kinase (CK) concentrations were measured until 60 min after the injection of suxamethonium. Both myoglobin and CK concentrations increased in the three groups receiving suxamethonium. There were no significant differences between groups S and ST2, but the myoglobin concentration was less in group ST4 than in groups S and ST2. A significant difference in CK concentration was found only between groups ST2 and ST4 at 60 min. In group N, both values remained reasonably constant. Thiopentone 4 mg kg-1, but not 2 mg kg-1, attenuated the increase. The results indicate that to prevent a marked elevation in serum myoglobin after administration of suxamethonium, thiopentone 4 mg kg-1 should be administered.

Adolescent↗
PubMed1993

The role of macrophages in antigen presentation and T cell tolerance.

Bone marrow derived cells (dendritic cells, macrophages and B cells) are involved in antigen presentation and T cell tolerance. However, the precise functions of each cell type remain unclear. To determine the role of macrophages we produced transgenic mice expressing I-E molecules only on macrophages, by introducing the hybrid gene containing the colony stimulating factor-1 (CSF-1) receptor promoter region and the structural gene encoding E alpha d into C57BL/6 mice. In these mice I-E restricted antigen presentation and T cell priming were impaired. With respect to T cell tolerance, I-E reactive T cells were anergized but not clonally deleted. These results clearly demonstrate that macrophages by themselves are defective in efficient I-E restricted antigen presentation, so that T cells exposed to antigens expressed on macrophages are led to anergy.

Animals↗
PubMed1993

Irreversible suppression of CD8 expression in CD4-CD8+ thymocytes upon in vitro stimulation.

CD8 (Ly-2) expression was suppressed in purified murine CD4-CD8+ thymocytes at the mRNA level upon continuous stimulation with PMA and ionomycin in the presence of rIL-2. The level of CD8 expression on CD4-CD8+ thymocytes was reduced gradually during the culture and a majority of them turned into CD4-CD8- cells after 48 hr. This suppression was not transient, since CD8 expression was not recovered on these cells in additional 48 hr of culture without PMA and ionomycin. The suppression was dependent on the concentrations of PMA and ionomycin, and inhibited by adding an immunosuppressant, CsA to the culture. Treatment with either PMA or ionomycin alone did not induce suppression of CD8. Crosslinking of CD3-epsilon chains also induced suppression of CD8 for a part of CD4-CD8+ thymocytes. Interestingly, CD8 expression was hardly suppressed in CD4-CD8+ peripheral T lymphocytes, suggesting that the mechanisms of suppression of CD8 is developmentally regulated. We propose that the suppression of CD8 expression at CD4-CD8+ stage involves an additional mechanism of negative selection of thymic T cells.

Animals↗
PubMed1993

[Effect of succinylcholine on serum potassium concentration in children with chronic renal failure].

Serum potassium (K+) levels were measured after intravenous injection of succinylcholine (SCh) in 10 children with chronic renal failure, 10 normal children aged 1 to 10 years and 10 children with chronic renal failure after pretreatment with pancuronium prior to SCh. Arterial blood gas was maintained within normal ranges. The serum K+ level increased significantly during 10 minutes after SCh in normal children. There was no significant difference between serum K+ levels in normal children and those in children with chronic renal failure. Administration of pancuronium in small doses (20 micrograms.kg-1) prior to SCh (1 mg.kg-1) was not effective to prevent serum K+ elevation completely. Our results indicate that the administration of SCh in children with chronic renal failure might be possible without increasing serum potassium level.

Child↗
PubMed1992

Irradiation increases levels of GM-CSF through RNA stabilization which requires an AU-rich region in cancer cells.

Granulocyte/macrophage colony stimulating factor (GM-CSF) is a hematopoietic growth factor that stimulates a wide range of myeloid hematopoietic cells; RNAs coding for many oncogenes and cytokines including GM-CSF have a very short half-life. The motif of AUUUA is a highly conserved sequence in the 3'untranslated regions (3'UTR) of these transcripts and is repeated a number of times in these short-lived cytokines and oncogenes. These sequences play a major role in controlling stability of these transcripts. Human cancer cells were transfected with a chimeric rabbit beta-globin gene linked to either a 58 bp sequence of the AT-rich region from GM-CSF or a control sequence. We have found that irradiation stimulates accumulation of GM-CSF, interleukin-6 (IL-6), and IL-1 beta RNAs. In addition, this accumulation of GM-CSF was at least, in part, a result of increased stabilization of GM-CSF transcripts. Further experiments showed that irradiation increased levels of the chimeric beta-globin transcripts containing AUUUA sequences from GM-CSF, but not those containing the control sequences. Our results suggest that irradiation increases expression of GM-CSF RNA and that posttranscriptional stabilization requiring AUUUA sequences probably is in part one of the mechanisms producing the increased levels of GM-CSF RNA by irradiation.

Base Sequence↗