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Biomedical subjects

F Takaku

Publications and source records attributed to F Takaku.

At least 271 records · Page 15Linked to original sources
PubMed1989

Tyrosine phosphorylation of pp185 by insulin receptor kinase in a cell-free system.

Insulin treatment of rat H-35 hepatoma cells causes rapid tyrosine phosphorylation of a high molecular weight protein termed pp185 besides autophosphorylation of the beta-subunit of the insulin receptor (IR) in an intact cell system. To elucidate the molecular basis for tyrosine phosphorylation of pp185, cell-free phosphorylation of pp185 was performed using phosphotyrosine-containing proteins (PYPs) purified from detergent-solubilized cell lysates by immunoprecipitation with anti-phosphotyrosine antibody. After insulin treatment of cells, marked increases of tyrosine phosphorylation of pp185 and IR were observed compared to noninsulin-treated cells. Site-specific antibodies that specifically inactivate IR kinase inhibited tyrosine phosphorylation of pp185 as well as the beta-subunit of IR. PYPs purified from detergent-free cell extracts contained pp185 but little IR; tyrosine phosphorylation of pp185 did not occur. Addition of IR kinase purified from human placenta to these PYPs restored insulin-dependent tyrosine phosphorylation of pp185. These results suggest that tyrosine phosphorylation of pp185 is catalyzed directly by IR kinase in this cell-free system.

Animals↗
PubMed1989

Transforming growth factor-beta stimulates the expression of endothelin mRNA by vascular endothelial cells.

Endothelin is a potent vasoconstrictor peptide produced by vascular endothelial cells. Incubation of the serum-deprived confluent porcine aortic endothelial cells with 10-300 pM TGF-beta 1, resulted in a several fold increase in endothelin mRNA levels with a peak time of 2 h. An enzyme-linked immunosorbent assay revealed that the levels of endothelin in endothelial cell conditioned media was also increased by TGF-beta 1. These results suggest that TGF-beta 1, secreted by activated platelets, is involved not only in wound healing, but in the regulation of local vascular tone by stimulating endothelin production in the endothelial cells.

Animals↗
PubMed1989

Tumor necrosis factor as an activator of human granulocytes. Potentiation of the metabolisms triggered by the Ca2+-mobilizing agonists.

TNF stimulated superoxide (O2-) release directly in human granulocytes in a dose-dependent manner (1 to 1000 U/ml), although its potency was weak. TNF-induced O2- release was inhibited by cAMP agonists or ionomycin, and was not accompanied with an increase in cytoplasmic free Ca2+ [( Ca2+]i) and membrane potential changes (depolarization). These findings indicate that neither Ca2+ mobilization nor membrane depolarization is required for TNF-receptor-mediated cell activation. The pretreatment of human granulocytes with TNF enhanced O2- release and membrane depolarization in parallel stimulated by the receptor-mediated Ca2+-mobilizing agonists (FMLP, Con A, and wheat germ agglutinin) or the Ca2+ ionophore ionomycin, but not by PMA, a direct activator of protein kinase C. The optimal effect was obtained by pretreatment of cells with 100 U/ml TNF for 5 to 10 min at 37 degrees C, although the magnitude of enhancement varied according to the agonists used as subsequent stimuli. TNF did not affect an increase in [Ca2+]i stimulated by the Ca2+-mobilizing agonists, except Con A. Con A-induced increase in [Ca2+]i was enhanced by TNF in a dose-dependent manner. These diverse effects of TNF could be partly explained by the exclusive potentiation by TNF of the metabolic events triggered by an increase in [Ca2+]i.

Adjuvants, Immunologic↗
PubMed1989

Rabbit brain glucose transporter responds to insulin when expressed in insulin-sensitive Chinese hamster ovary cells.

Transfection of Chinese hamster ovary cells with the expression vector containing rabbit brain HepG2-type glucose transporter cDNA resulted in a dramatic over-expression (approximately 10-fold) of glucose transporter as assessed by either immunoblotting with antipeptide antibody against rabbit brain glucose transporter or photoaffinity labeling with [3H]cytochalasin B. 2-Deoxyglucose uptake was also increased 4-fold in the transfected cells, while no increase in transport activity or transporter amount was observed in cells that were transfected with the expression vector alone without glucose transporter cDNA. Significantly, insulin (10(-7) M) increased 2-deoxyglucose uptake in both control and transfected cells, but the increased amount of the transported 2-deoxyglucose by insulin in the transfected cells was 4.2-fold greater than that in control cells, indicating that the expressed rabbit brain HepG2-type glucose transporter responded to insulin. In addition, we have recently demonstrated that the HepG2-type glucose transporter exists in rat adipocytes and responds to insulin in a fashion similar to a majority of other types of glucose transporters (Oka, Y., Asano, T., Shibasaki, Y., Kasuga, M., Kanazawa, Y., and Takaku, F. (1988) J. Biol. Chem. 263, 13432-13439). In contrast, insulin did not stimulate glucose transport activity in HepG2 cells or IM-9 lymphocytes that have a significant amount of the HepG2-type glucose transporter. Thus, the results in this study further support the notion that insulin regulation of glucose transport activity depends on a tissue-specific signaling mechanism.

Affinity Labels↗
PubMed1989

Erythrocyte enzyme activities in myelodysplastic syndromes: elevated pyruvate kinase activity.

The erythrocyte enzyme activities in twenty-six cases of myelodysplastic syndromes were determined. There were remarkably abnormal levels in seven cases; namely, four cases showed increased hexokinase activity, three cases showed increased pyruvate kinase activity, and two cases showed increased adenosine deaminase activity. Among these, one case with elevated pyruvate kinase activity showed the novel expression of M2-type pyruvate kinase activity, in addition to the R-type pyruvate kinase activity normally found in erythrocytes. Southern blotting of peripheral leucocyte DNA revealed only an amplified PK-LR genome, which derived from the chromosomal abnormality of a 1;7 translocation. The mechanism responsible for switching M2-type to R-type during erythroid maturation was considered to be partially disrupted in this case.

Blotting, Southern↗
PubMed1989

Cachectin/TNF kills or inhibits the differentiation of 3T3-L1 cells according to developmental stage.

The effects of cachectin/tumor necrosis factor (TNF) on growth and differentiation of 3T3-L1 cells were examined. This fibroblastic cell line can be induced to differentiate into a mature cell type having the biochemical and morphological characteristics of normal adipocytes. At various stages of growth and differentiation, 3T3-L1 cells were exposed to 2.5 x 10(-16) to 2.5 x 10(-8) M (4.2 fg/ml to 420 ng/ml = ca. 1.2 x 10(-14) to 1.2 x 10(-16) U/ml) recombinant human cachectin/TNF for 24 hr, after which cytotoxicity or differentiation was evaluated. During log-phase cell growth, cachectin/TNF had no significant effect on cell viability, and the preadipocytic cells were also resistant to the cytotoxic effect of cachectin/TNF at the contact-inhibited confluent stage. However, when cachectin/TNF was added to the cells during induced differentiation, only 20% of the cells survived. After differentiation into adipocytes, cells regained their resistance to cachectin/TNF-induced cytotoxicity. Cachectin/TNF also markedly affected the differentiation of 3T3-L1 cells into adipocytes. When cells in the confluent phase of growth were exposed to cachectin/TNF for 24 hr, their subsequent hormone-induced differentiation to adipocytes was inhibited. Like cachectin/TNF, IL-1 also induces suppression of lipoprotein lipase and enhances lipolysis in differentiated 3T3-L1 adipocytes; however, in contrast to cachectin/TNF, IL-1 had no effect on the viability or differentiation of pre-adipocyte 3T3-L1 cells. These results indicate that the cytotoxic action of cachectin/TNF varies in the same cell type depending on the stage of growth or differentiation. The results also imply that cachectin/TNF may play a normal role in controlling the differentiation of certain types of cells in vivo including adipocyte lineages.

Animals↗
PubMed1989

Establishment and characterization of a unique human cell line that proliferates dependently on GM-CSF, IL-3, or erythropoietin.

We have established a novel cell line, designated as TF-1, from a patient with erythroleukemia, which showed complete growth dependency on granulocyte-macrophage colony-stimulating factor (GM-CSF) or on interleukin-3 (IL-3) and carried a homogeneous chromosomal abnormality (54X). Erythropoietin (EPO) also sustained the short-term growth of TF-1, but did not induce erythroid differentiation. These three hematopoietic growth factors acted on TF-1 synergistically. Transforming growth factor-beta and interferons inhibited the factor-dependent growth of TF-1 cells in a dose-dependent fashion, and monocyte-colony stimulating factor and interkeukin-1 enhanced the GM-CSF-dependent growth of TF-1. Ultrastructural studies revealed some very immature features in this cell line. Although TF-1 cells do not express glycophorin A or carbonyl anhydrase I, the morphological and cytochemical features, and the constitutive expression of globin genes, indicate the commitment of TF-1 to erythroid lineage. When induced to differentiate, TF-1 entered two different pathways. Specifically, hemin and delta-aminolevulinic acid induced hemoglobin synthesis, whereas TPA induced dramatic differentiation of TF-1 into macrophage-like cells. In summary, TF-1 is a cell line of immature erythroid origin that requires GM-CSF, IL-3, or EPO for its growth and that has the ability to undergo differentiation into either more mature erythroid cells or into macrophage-like cells. TF-1 is a useful tool for analyzing the human receptors for IL-3, GM-CSF, and EPO or the signal transduction of these hemopoietic growth factors.

Adult↗
PubMed1989

Effects of recombinant human erythropoietin on hematopoietic progenitors of chronic hemodialysis patients in vitro and in vivo.

Erythroid progenitors were assayed in 20 chronic hemodialysis patients before and after administration of recombinant human erythropoietin (rhEpo) using a methylcellulose culture method. Hemoglobin concentrations, hematocrit values and the proportion of marrow erythroblasts increased significantly during rhEpo treatment. The numbers of erythroid progenitors (CFU-e and BFU-e) in the patients' marrow also increased following rhEpo administration. Our data suggest that rhEpo is an effective drug for treating anemia caused by chronic renal failure and the administration of rhEpo results in an increase in the numbers of erythroid progenitors.

Adult↗
PubMed1989

Measurement of human G-CSF by enzyme-linked immunosorbent assay using monoclonal antibody.

An IgG monoclonal antibody to recombinant human granulocyte colony-stimulating factor (G-CSF), designated HG1, was produced by fusion of immune mouse splenocytes with HAT-sensitive murine myeloma cells. This HG1 was capable of neutralizing the colony-stimulating activity of G-CSF in vitro, and it did not cross-react with human granulocyte/macrophage colony-stimulating factor (GM-CSF). An enzyme-linked immunosorbent assay (ELISA) for measurement of G-CSF was developed using HG1 and a polyclonal antibody against G-CSF raised in a rabbit. The data indicated that the ELISA was highly efficient and sensitive for the detection of as little as 50 pg/ml of recombinant G-CSF. This assay system therefore warrants further attention.

Antibodies, Monoclonal↗
PubMed1989

Treatment of myelodysplastic syndromes with recombinant human granulocyte colony-stimulating factor: a preliminary report.

PURPOSE: The expansion of an abnormal hemopoietic stem cell line is responsible for the myelodysplastic syndromes, which are characterized by pancytopenias, often resulting in lethal infections. Cloned granulocyte colony-stimulating factor (G-CSF) was recently shown to enhance the growth and differentiation of normal granulocyte progenitor cells in vitro. The aim of our study was to examine the effects of recombinant human G-CSF in patients with myelodysplastic syndromes. PATIENTS AND METHODS: Four patients with myelodysplastic syndromes and one patient with smoldering acute myelogenous leukemia following the occurrence of a myelodysplastic syndrome received recombinant human G-CSF by intravenous infusion for six days. Patients received different dosage levels (50 to 1,600 micrograms/m2). RESULTS: A response was seen in all patients, with an increase in both immature myeloid cells in the bone marrow and mature granulocytes in the peripheral blood. The dose levels that could stimulate granulocytopoiesis differed among patients. CONCLUSION: These results suggest that, at least in some cases of myelodysplastic syndromes, granulocytopenia can be improved by G-CSF, although it still remains to be determined whether the increase in the number of granulocytes is due to the differentiation and maturation of the myelodysplastic clone or restoration of a residual normal clone.

Adult↗
PubMed1989

Plasma apolipoproteins in patients with multi-infarct dementia.

We examined 27 elderly patients with multi-infarct dementia developed on the basis of cerebral arteriosclerosis. The levels of plasma cholesterol and triglyceride in the patients were 177 +/- 48 and 91 +/- 27 mg/dl (mean +/- SD), respectively. Despite normal plasma lipid levels, the patients had significantly higher plasma apo B (102 +/- 30 vs. 82 +/- 21 mg/dl for controls, P less than 0.01) and lower plasma apo A-I levels (104 +/- 25 vs. 130 +/- 22 mg/dl for controls, P less than 0.01) than the controls. Isoelectric focusing of apo E showed a 2-fold higher relative frequency for the epsilon 4 allele in patients than in Japanese controls (20.8 vs. 8.6-11.7% of total, P less than 0.05). The patients with phenotypes of E4/4 (n = 1) and E4/3 (n = 8) had higher plasma cholesterol levels than those with E3/3 (n = 15) (196 +/- 45 vs. 169 +/- 43 mg/dl). The results indicate that the patients had abnormalities in plasma lipoprotein metabolism and this may contribute to the development of cerebral arteriosclerosis.

Aged↗
PubMed1989

Effect of long-term treatment with beta-blocker on cardiac hypertrophy in SHR.

Recent studies suggest that beta-blocker treatment may attenuate cardiac hypertrophy induced by pressure overload in the spontaneously hypertensive rat (SHR), but the effect of this therapy on the reconstitution of the intracellular constituents in the heart that occurs during the development of cardiac hypertrophy has not been examined. In this study, we investigated the effect of chronic administration of carteolol (4 mg/kg/day p.o.) or propranolol (20 mg/kg/day p.o.), beta-blockers with distinct modes of action, on the composition of cardiac myosin isozymes and histological findings as well as heart weight. Therapeutic periods were 4, 12 or 30 weeks. Though blood pressure was not significantly reduced, the development of cardiac hypertrophy was suppressed as evidenced by left ventricular weight in both groups of carteolol- and propranolol-treated SHR for all therapeutic periods. Again, beta-blocker treatment for 12 weeks alleviated myocardial degeneration and reactive fibrosis which were observed in all cases of age-matched untreated SHR. However the extent of the transition of cardiac myosin isozymes from V1 to V2 or V3 were essentially the same among all groups including untreated SHR. These results indicate that chronic administration of beta-blockers attenuates the development of cardiac hypertrophy and degeneration without affecting the transition of myosin isozymes which is thought to be a kind of biochemical adaptation of the myocardium to overload.

Adrenergic beta-Antagonists↗
PubMed1989

Endothelin: a potent vasoconstrictor associated with coronary vasospasm.

Endothelin, administered into the coronary arteries of anesthetized dogs, produced a profound and long-lasting reduction in coronary blood flow with electrocardiographical evidence of myocardial ischemia. Coronary angiography revealed delayed filling of the distal branches and, in some cases, cessation of the blood flow distal to the epicardial portions of coronary arteries. The coronary vasoconstriction induced by endothelin subsided after intracoronary administration of nitroglycerin. Pretreatment with the Ca2+-channel antagonist, nitrendipine, suppressed endothelin-induced vasoconstriction. These findings suggest that endothelin, produced by vascular endothelial cells, may contribute to the pathogenesis of coronary vasospasm.

Animals↗
PubMed1989

Platelet-derived growth factors.

Blood platelets are a rich source of growth factors, including platelet-derived growth factor, platelet-derived endothelial cell growth factor, and transforming growth factor beta. Platelet-derived growth factor stimulates the growth of mesenchymal cells such as fibroblasts and vascular smooth muscle cells, whereas platelet-derived endothelial cell growth factor is a mitogen for vascular endothelial cells. Transforming growth factor beta is a bifunctional regulator of cellular growth, but acts as a potent inhibitor for most cell types. Most of the growth regulatory substances in platelets have been reported to reside in platelet alpha-granules, but platelet-derived endothelial cell growth factor appears to be present in platelet cytoplasm. These growth factors may act at sites of injury as wound hormones. Moreover, they play important roles for some pathological conditions such as atherosclerosis, myelofibrosis, connective tissue diseases, and neoplastic disorders.

Animals↗
PubMed1989

Endobronchial non-Hodgkin's lymphoma.

A 64-year-old man with non-Hodgkin's lymphoma suffered a complete collapse of the left upper lobe of the lung. Fibreoptic bronchoscopy demonstrated a large number of distinct polypoid tumours of the lymphoma in the trachea and bilateral sub-segmental bronchi. The left upper lobe bronchus was completely occluded by the tumours, which responded to the combination chemotherapy against the lymphoma. This report presents the seventh case of non-Hodgkin's lymphoma with multiple endobronchial tumours.

Antineoplastic Combined Chemotherapy Protocols↗