Biomedical subjects

H Miyazaki

Publications and source records attributed to H Miyazaki.

At least 325 records · Page 18Linked to original sources

PubMed1996

Improvement of thrombocytopenia following bone marrow transplantation by pegylated recombinant human megakaryocyte growth and development factor in mice.

We examined whether pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF) is capable of improving thrombocytopenia and promoting thrombopoietic reconstitution following lethal irradiation and bone marrow transplantation (BMT) in mice. Immediately after receiving 10 Gy whole body irradiation (day 0), male C3H/HeN mice were inoculated with 10(6) bone marrow cells obtained from syngeneic mice. Circulating platelet counts decreased to below 4% of the normal counts with a nadir on day 10, and then returned to the normal level on day 28 in the control mice undergoing BMT. Subcutaneous consecutive treatment with PEG-rHuMGDF at doses from 10 to 300 micrograms/kg/day from day 1 for 13 days significantly improved the platelet nadir and promoted platelet recovery. The white blood cell counts and hemoglobin concentration following BMT were not influenced by the PEG-rHuMGDF. PEG-rHuMGDF-injection starting from day 5 did not improve the platelet nadir following BMT. Furthermore, administration with PEG-rHuMGDF on alternate days at 55.7 micrograms/kg/day for 7 days or at an interval of 3 days at 78 micrograms/kg/day for 4 days (twice a week for 2 weeks) had a significant efficacy, but these administration regimens had less efficacy than consecutive administration at 30 micrograms/kg/day for 13 days. The numbers of megakaryocytes and megakaryocyte progenitor cells decreased to 5 and 0.2% of normal level, respectively, in the control mice. Consecutive administration of PEG-rHuMGDF enhanced the recovery of the mean number of these cells compared to those in vehicle-treated mice, although such effects were not statistically significant except for the number of megakaryocyte progenitors on day 12. These results suggest that consecutive treatment with PEG-rHuMGDF beginning from the day after BMT may be effective in improving thrombocytopenia following BMT.

Animals↗

PubMed1996

[Interstitial pneumonia treated with intermittent cyclophosphamide pulse therapy].

A 52-year-old woman was admitted to the hospital because of polyarthralgia and dry coughing. A chest X-ray film showed bilateral diffuse reticulo-nodular shadows. A specimen obtained by transbronchial lung biopsy revealed alveolar septal thickening and infiltration by mononuclear cells. Interstitial pneumonia associated with rheumatoid arthritis was diagnosed. Interstitial pneumonia relapsed soon after the first pulse of corticosteroid therapy. Cyclophosphamide pulse therapy was given in addition to a second pulse of corticosteroid therapy; 700 mg of cyclophosphamide (500 mg/m2) was administered intravenously every month and the dose of steroids was gradually reduced. Cyclophosphamide pulse therapy was repeated three times and the dose of oral corticosteroids was reduced from 60 mg to 35 mg. There was no bone marrow suppression or hemorrhagic cystitis after the cyclophosphamide pulses. Eventually, corticosteroid therapy was stopped with no clinical deterioration. This case suggests that intermittent cyclophosphamide pulse therapy can be effective for treatment of interstitial pneumonia unresponsive to corticosteroids.

Arthritis, Rheumatoid↗

PubMed1996

[Effective clinical use of cyclophosphamide in hematological malignancies].

Cyclophosphamide (CPA) is the most widely used alkylating agent in the treatment of hematological malignancies. We review current clinical potential of high-dose CPA administration in this field. The efficacy of dose intensification of CPA in CHOP regimen for patients with aggressive lymphoma is being investigated in some clinical trials. High-dose CPA administration and G-CSF infusion effectively mobilize high levels of peripheral blood stem cell suitable for autografting. High-dose regimens of CPA alone or in combination with other agents also have been used to treat various hematological malignancies in conjunction with stem cell transplantation (SCT). A variety of adverse effects have been observed with the high-dose CPA used in preparative regimens for SCT. Hemorrhagic cystitis and cardiac toxicity are common and dose-limiting toxic effect of high-dose CPA administration.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1995

Thrombopoietin induces tyrosine phosphorylation and activation of mitogen-activated protein kinases in a human thrombopoietin-dependent cell line.

Thrombopoietin (TPO) is a cytokine which can support the proliferation and differentiation of megakaryocyte progenitor cells, and the maturation of megakaryocytes. We show here that mitogen-activated protein (MAP) kinases, Erk1 and Erk2, are involved in TPO signal transduction in the human TPO-dependent megakaryocytic cell line, UT-7/TPO. TPO induced tyrosine phosphorylation of Erk1 and Erk2 proteins in a dose and time-dependent manner. Moreover, the activation of MAP kinases was actually induced by TPO. These results suggest that MAP kinase activation is involved in the signalling pathway of TPO, as it is for other cytokines, one of which is erythropoietin.

Calcium-Calmodulin-Dependent Protein Kinases↗

PubMed1995

Recombinant human thrombopoietin (Mpl ligand) enhances proliferation of erythroid progenitors.

We have studied the effects of recombinant human thrombopoietin (TPO, Mpl ligand) on human hematopoiesis in vitro. TPO alone did not support erythroid burst formation but, in the presence of erythropoietin, it enhanced erythroid burst formation from CD34+ bone marrow and cord blood cells. The burst-promoting activity (BPA) was stronger under 5% serum than 30% serum conditions. The direct nature of BPA effects was documented by replating studies of early erythroid bursts. The BPA of TPO was less than that of interleukin-3 but was comparable with that of granulocyte/macrophage colony-stimulating factor and steel factor. The soluble form of Mpl receptor inhibited burst enhancing effects of TPO, suggesting that the BPA effects of TPO are mediated through the Mpl receptor. These results further delineate the physiologic roles of TPO and may aid in the determination of the clinical usages of TPO.

Adult↗

PubMed1995

A positive regulatory gene, pvdS, for expression of pyoverdin biosynthetic genes in Pseudomonas aeruginosa PAO.

In response to iron limitation Pseudomonas aeruginosa PAO induces production of pyoverdin, a low-molecular-weight siderophore able to capture ferric ion with a very high affinity. The pvd genes involved in the pyoverdin biosynthesis are organized in a chromosomal region termed the pvd region, and expression of some pvd genes is regulated at the transcriptional level. Two sets of promoter regions for the pvd genes were defined that were transcriptionally derepressed under iron-limiting conditions. Analysis of transcription from such promoters in Escherichia coli led to isolation and identification of a positive regulatory gene, pvdS, for expression of the pvd genes, and pvdS was localized in the pvd region. A genomic pvdS mutant of PAO, constructed by allelic exchange mutagenesis, produced no pyoverdin and did not allow transcription from the pvd promoters. Nucleotide sequence analysis revealed that PvdS shows considerable similarity to FecI of E. coli, a positive regulator for transcription of the fec (ferric citrate transport system) operon. The promoter region of pvdS has the sequence that matches well the consensus binding site for the E. coli Fur protein, a global negative regulatory protein that represses the transcription of the iron-repressible genes. Consistent with the presence of such a consensus sequence, addition of iron repressed transcription of the pvdS gene in P. aeruginosa.

Amino Acid Sequence↗

PubMed1995

Recombinant thrombopoietin induces rapid protein tyrosine phosphorylation of Janus kinase 2 and Shc in human blood platelets.

A cDNA for the thrombopoietin has been cloned by several groups. The recombinant thrombopoietin has been reported to stimulate the megakaryocytopoiesis and thrombopoiesis. Little is known regarding the molecular basis of its effects. To elucidate the molecular mechanism involved in signal transduction, we have investigated the effects of thrombopoietin on platelet tyrosine phosphorylation. We report here that thrombopoietin induced time- and dose-dependent tyrosine phosphorylation of several proteins including Janus kinase 2 (Jak2) and a 52-kD protein, Shc, in human blood platelets. Both Jak2 and Shc were tyrosine phosphorylated within 15 seconds after stimulation. The tyrosine phosphorylation of Jak2 was accompanied by increased kinase activity, whereas Shc tyrosine phosphorylation induced its association with a 25-kD protein, Grb2. Thus, our data suggest that Jak2, Shc, and Grb2 may be involved in signal transduction after ligand binding to c-mpl in human platelets.

Adaptor Proteins, Signal Transducing↗

PubMed1995

Cloning of the rat angiotensin II type 2 receptor gene and identification of its functional promoter region.

We have cloned the rat angiotensin II receptor type 2 (AT2) gene, whose physiological function remains unclear. Sequence analysis indicated that exons 1 and 2 exist in the 5'-untranslated region and the initiation codon ATG is located in exon 3. The 1.6-kb genomic fragment at positions -1567 to +26 relative to the putative transcription start site was found to contain a functional promoter region using transient chloramphenicol acetyltransferase assay. This is the first report demonstrating the nucleotide sequence of the promoter region of this gene.

Animals↗

PubMed1995

The sequence of a rat cDNA encoding thrombopoietin.

Overlapping cDNA clones encoding rat thrombopoietin (TPO) were isolated from liver-derived cell line cDNA libraries and the nucleotide sequences were determined. The deduced 326-amino-acid rat TPO showed significant homology to the known TPO of other species, especially in the N-terminal sequence.

Amino Acid Sequence↗

PubMed1995

Characterization of angiotensin II receptor type 2 during differentiation and apoptosis of rat ovarian cultured granulosa cells.

We examined the change in the content of angiotensin II (AII) receptor type 2 (AT2) during differentiation and apoptosis of rat ovarian granulosa cells in culture. The AT2 content was not changed by follicle stimulating hormone (FSH), a differentiation factor of granulosa cells, but was markedly increased in FSH-free media. The cells cultured without FSH underwent internucleosomal DNA fragmentation characteristic of apoptosis, which occurs during follicle atresia. AII augmented the increase in the AT2 content in the absence of FSH. This AII-induced augmentation was suppressed by the AT2-selective antagonist PD123319 but not by Dup753, an antagonist specific for type 1 receptor, suggesting that AII up-regulates the AT2 expression via AT2 itself. These data strongly support the hypothesis that AT2 might modulate the onset and progression of follicle atresia involving apoptosis of granulosa cells.

Angiotensin II↗

PubMed1995

Improvement of blood compatibility on cellulose dialysis membrane. III. Synthesis and performance of water-soluble cellulose grafted with phospholipid polymer as coating material on cellulose dialysis membrane.

To improve the surface blood compatibility on a cellulose hemodialysis membrane, a blood compatible polymer with a phospholipid polar group, poly[2-methacryloyloxyethyl phosphorylcholine(MPC)], was immobilized on the surface through the coating of a water-soluble cellulose grafted with poly(MPC) (MPC-grafted cellulose, MGC). The MGC was synthesized by graft copolymerization of MPC on a water-soluble cellulose using cerium ion as an initiator. The coating process on the cellulose membrane with an aqueous solution of the MGC was convenient, and the MGC on the surface was not significantly detached even after immersion in water. The permeability and mechanical strength of the membrane coated with the MGC did not decrease compared with the original membranes. The MGC-coated cellulose membrane was blood compatible, as determined by the prevention of platelet adhesion and aggregation after contact with platelet-rich plasma. From these results, it is concluded that the MGC may be a useful material for improving the blood compatibility of the cellulose hemodialysis membrane.

Animals↗

PubMed1995

Differing kinase activity of the c-yes and c-src gene proteins in TPA-induced megakaryocytic differentiation of T-33 and K562 cell lines.

We examined the protein kinase (PK) activity of the c-yes and c-src gene proteins (c-YES, c-SRC) at an early phase of 12-O-tetradecanoyl phorbol-13-acetate (TPA)-induced megakaryocytic differentiation of T-33 and K562 cells with use of immunoprecipitation and in vitro kinase assay. We found that c-SRC PK activity of TPA-treated T-33 and K562 cell lines had been enhanced compared with the untreated ones, but in contrast, no enhancement of c-YES PK activity by the TPA treatment was observed in these cell lines. We also examined PK activity in TPA-induced monocytic differentiation of U937 monoblastic cells that exhibited no megakaryocytic markers and found that both the c-YES and c-SRC PK activity was enhanced by the TPA treatment. Our data suggest that c-YES and c-SRC play different and unique roles in TPA-induced megakaryocytic differentiation in T-33 and K562 cells.

Cell Differentiation↗

PubMed1995

Interleukin-1 beta (IL-1 beta) and acute leukemia: in vitro proliferative response to IL-1 beta, IL-1 beta content of leukemic cells and treatment outcome.

We evaluated the in vitro proliferative response to exogenous IL-1 beta in terms of tritiated thymidine (3H-TdR) incorporation in leukemic cells obtained from 119 patients with various types of acute leukemia. The content of IL-1 beta in leukemic cells was measured by enzyme-amplified sensitivity immunoassay. We observed a significant proliferative response to exogenous IL-1 beta in leukemic cells from 27/66 patients with de novo AML, 1/29 patients with ALL, 2/3 patients with AUL, 8/12 patients with AML arising from MDS, 4/7 patients with myeloid crisis of CML, and 0/4 patients with lymphoid crisis of CML. Proliferation was marked in myeloid leukemic cells of a more premature stem cell origin. There were no significant differences in proliferative responses among the different FAB classes of de novo AML. The IL-1 beta content of leukemic cells was low in patients with lymphoid leukemia, but there was no significant difference among the various types of myeloid leukemia. There was no correlation between the proliferative response to exogenous IL-1 beta and the IL-1 beta content of leukemic cells. When we correlated the proliferative response to exogenous IL-1 beta with treatment outcome in patients with de novo AML, we found the rate of complete remission (CR) to be lower in those with a high proliferative response. We noted a longer duration of CR (p = 0.07) and of survival (p < 0.05) in patients with a low proliferative response. Thus, a high proliferative response to IL-1 beta in the cells of AML patients may indicate a poor prognosis.

Acute Disease↗

PubMed1995

Biliary secretion of antibody to dextran following oral immunization with dextran B512.

Anti-dextran in bile was induced to high levels by oral immunization with dextran B512. IgM anti-dextran were dominant in serum, whereas IgG anti-dextran was dominant in bile. The binding properties of these IgM and IgG antibodies were different, as determined by ELISA with several dextrans. Splenocytes produced equal amounts of IgG and IgM antidextran but cells from mesenteric lymph nodes (MLN) and Peyer's patches produced mainly IgG anti-dextran. Differences were observed among different strains of mice in their ability to produce anti-dextran in serum and bile upon immunization with dextran. BALB/c mice, which are intermediate responders in terms of their serum antibody levels, produced high levels of anti-dextran in bile. C3H/He and C57BL/6, which are high responders in terms of serum antibody levels, had intermediate responses in bile. DBA/2, which are low responders in terms of serum antibody levels, showed low responses in bile. The results provide further evidence of the existence of anti-dextran producing cells. These results indicate that B cells in systemic and mucosal-associated lymphoid tissues from BALB/c, C3H/He, C57BL/6 and DBA/2 mice respond differently to oral immunization with dextran B512.

Administration, Oral↗

PubMed1995

Effect of sulfo-N-succinimidyl palmitate on the rat heart: myocardial long-chain fatty acid uptake and cardiac hypertrophy.

Abnormal long-chain fatty acid metabolism has been suggested as having a role in the genesis of certain cardiac diseases, and depressed myocardial long-chain fatty acid uptake has been clinically demonstrated in some patients with hypertrophic cardiomyopathy. However, the site where long-chain fatty acid metabolism is affected in cardiomyopathy remains unclear. Although cardiac hypertrophy is reported to be induced in rats by a fat-free diet, little is known of the consequences of depressed myocardial long-chain fatty acid uptake. Sulfo-N-succinimidyl derivatives of long-chain fatty acids have been shown to irreversibly inhibit long-chain fatty acid transport. To investigate the possible linkage of abnormal long-chain fatty acid uptake with cardiac hypertrophy, myocardial long-chain fatty acid uptake was blocked in rats using a sulfo-N-succinimidyl derivative of palmitate (SSP). SSP was intraperitoneally administered to rats for 12 weeks, and its effects on physiological parameters, and cardiac morphology were studied, SSP treatment (20 mg/kg) caused a 12% increase in heart weight (663.7 +/- 33.6 mg in controls v 741.2 +/- 26.5 mg after SSP treatment) and an 11% increase in the heart weight to body weight ratio (2.46 +/- 0.10 in controls v 2.72 +/- 0.17 after SSP) without any significant change of body weight. No significant differences were observed in blood pressure, heart rate, and serum hormones (insulin and triiodothyronine) between the control and SSP-treated groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗

PubMed1995

Purification of low-molecular-weight GTP-binding proteins structurally related to MTG33, a mitochondrial GTP-binding protein of Ehrlich ascites tumor cells.

We purified a mitochondrial GTP-binding protein, MTG33, from a particulate fraction of Ehrlich ascites tumor cells [Takeda, S., Sagara, Y., Kita, K., Natori, S., and Sekimizu, K. (1993) J. Biochem. 114, 684-690]. In the present work, three GTP-binding proteins, p23A, p23B, and p26, were purified from the same material. The Kd values of p23A, p23B, and p26 for GTP were 19, 6.8, and 4.0 nM, respectively. Binding of [alpha-32P]GTP to these proteins was inhibited by GTP and GDP, but not appreciably by other nucleotides such as ATP, CTP, UTP, and GMP. p23A, p23B, and p26 hydrolyzed GTP to GDP as well as MTG33 did. Peptide mapping analyses revealed that these GTP-binding proteins share common primary structures with MTG33. The defined properties of the three proteins suggest structural and functional relations to MTG33, which is localized in mitochondria.

Animals↗

PubMed1995

Establishment and characterization of a new human mesothelioma cell line (T-85) from malignant peritoneal mesothelioma with remarkable thrombocytosis.

A mesothelioma cell line, termed T-85, was established from a patient with malignant peritoneal mesothelioma and remarkable thrombocytosis (1.4 x 10(6)/mm3). Electron microscopically, two types of mesothelioma cells have been characterized; the major type of cells with dense-cored granules in the cytoplasm and the minor one with evenly dense granules. Immunologically, the cells showed staining for interleukin-6 (IL-6), cytokeratin, collagen type IV, vimentin, laminin, fibronectin and Factor VIII-related antigen. Quantitation by ELISA revealed a high concentration of IL-6 in T-85 cell culture supernatants. RT-polymerase chain reaction of T-85 cells showed two positive bands of cDNA at 628 and 251 base pairs indicating the constitutive expression of IL-6 and IL-6 receptor mRNA. Moreover, prominent pro-platelet process formation activity in T-85 cell culture supernatants indicated the presence of a thrombopoietic activity due mainly to IL-6 but not the c-Mpl ligand or erythropoietin. However, the fact that 15% of PPF activity remained in the supernatants treated with anti-IL-6 antibody indicated the presence of another thrombopoietic substance. T-85 is so far the first mesothelioma cell line derived from a case with remarkable thrombocytosis.

Base Sequence↗

PubMed1995

Effects of GTP gamma S on muscarinic receptor-stimulated inositol phospholipid hydrolysis in permeabilized smooth muscle from the small intestine.

1. Smooth muscle fragments from the longitudinal layer of the small intestine of the guinea-pig were permeabilized with Staphylococcus aureus alpha toxin (alpha-toxin) and used to investigate the role of G-protein activation in the regulation of muscarinic acetylcholine receptor (AChR)-stimulated inositol phospholipid hydrolysis. 2. The efficiency of alpha-toxin permeabilization was estimated by the release of [3H]-2-deoxyglucose ([3H]-2DG) after prior loading or lactate dehydrogenase (LDH) enzyme release from the smooth muscle fragments. 3. In alpha-toxin-permeabilized smooth muscle, but not in non-permeabilized muscle, GTP gamma S induced time- and concentration-dependent increases in labelled inositol phosphates. Carbachol (CCh) increased labelled inositol phosphates in both permeabilized and non-permeabilized muscle, although the increases were greater in non-permeabilized smooth muscle. The response to 100 microM CCh was severely reduced by 0.5 microM atropine. 4. In permeabilized muscle the effects of GTP gamma S or CCh on inositol phosphate levels were reduced by treatment with pertussis toxin (PTX) and completely inhibited by GDP beta S. 5. GTP gamma S caused a concentration-dependent inhibition of the CCh-induced increases in the levels of labelled inositol phosphates. Dibutyryl cyclic AMP or Sp-cAMPs (adenosine-3',5'-cyclic phosphorothiolate-Sp) reduced the effects of CCh on inositol phosphate levels. 6. The results suggest that muscarinic AChR activation induces inositol phospholipid hydrolysis via more than one G-protein in this smooth muscle and that several mechanisms may contribute to the modulation of both stimulatory and inhibitory responses observed.

Animals↗