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Biomedical subjects

A Urabe

Publications and source records attributed to A Urabe.

At least 199 records · Page 11Linked to original sources
PubMed1987

Binding of erythropoietin to CFU-E derived from fetal mouse liver cells.

The binding of recombinant erythropoietin (EPO) to fetal mouse liver cells (FMLC) was investigated using a radioiodinated derivative which retained full biological activity. FMLC were fractionated using a preformed Percoll density gradient. Using the fractionated FMLC, the ability to form CFU-E colonies in a semisolid culture was examined, and the binding of [125I]EPO was measured. The highest specific binding of [125I]EPO was observed in a fraction with a density between 1.062 and 1.076 g/ml. The same fraction showed the highest ability to form CFU-E-derived colonies. After suspension culture of FMLC with EPO for 2 days, differentiated erythroid cells with higher density markedly increased. The specific binding of [125I]EPO to these cells almost disappeared with differentiation. Scatchard analysis with cells of the CFU-E-enriched fraction showed a nonlinear curve, suggesting the existence of two classes of binding sites. One binding site was high-affinity (Kd1 = 0.41 nM), and the other low-affinity (Kd2 = 3.13 nM). These results suggest that the expression of EPO receptors on the erythroid cells is highest in CFU-E.

Animals↗
PubMed1987

Effect of human recombinant granulocyte colony-stimulating factor on hematopoietic injury in mice induced by 5-fluorouracil.

Intravenous (IV) administration of 5-fluorouracil (5-FU) caused severe hematopoietic injury in mice. Daily administration of purified human recombinant granulocyte colony-stimulating factor (rG-CSF) accelerated recovery from neutropenia in these injured mice. Granulocyte-macrophage progenitors (CFU-GM) in spleen were markedly increased by rG-CSF, while rG-CSF was less effective on the regeneration of CFU-GM in femoral marrow. The accelerated recovery from neutropenia in the mice might be mainly due to the stimulation of granulopoiesis in spleen by rG-CSF.

Animals↗
PubMed1987

Pure erythropoietic colony and burst formations in serum-free culture and their enhancement by insulin-like growth factor I.

Recombinant human insulin-like growth factor I (IGF-I) increased human and murine erythropoietic colony formation in serum-free culture. In order to investigate the effects of purified factors such as IGF-I on hemopoietic progenitor cells, we have established a serum-free culture system which supports the clonal growth of CFU-E- and BFU-E-derived colonies. Exogenously supplied ingredients were bovine serum albumin (BSA), transferrin, lipid suspensions, 2-mercaptoethanol, and recombinant human erythropoietin (epo). Among these, BSA and cholesterol were found to be essential ingredients. The optimum concentration of BSA sufficient to grow BFU-E was 3%. Erythroid colony and burst formation of human and murine marrow cells was enhanced twofold (p less than 0.05) by a physiological concentration of recombinant human IGF-I. Potentiation was observed in a dose-dependent manner between 10(-9) and 10(-7) M. A few murine CFU-E colonies were formed in the absence of epo. These results suggest that IGF-I has a supportive effect on the proliferation and differentiation of erythroid precursor cells stimulated by epo and that its action is synergistic with that of epo.

Animals↗
PubMed1986

Burst-promoting activity in anemia and polycythemia.

Burst-promoting activity (BPA) in the sera of patients with various types of anemia and polycythemia was compared with that of normal subjects by an in vitro method using mouse bone marrow cells. The control culture contained normal human AB serum instead of sample materials. Results were expressed as a percentage of burst numbers in control cultures. Serum erythropoietin (Epo) levels were determined by a radioimmunoassay. Serum BPA in patients with aplastic anemia (155.4 +/- 56.7%, mean +/- SD) was significantly higher than that in normal subjects (112.1 +/- 29.1%, Wilcoxon's rank sum test, P less than 0.05). However, serum BPA in patients with uremic anemia (122.2 +/- 26.5%), polycythemia vera (101.9 +/- 19.5%) and stress polycythemia (115.5 +/- 25.6%) was not significantly different from normal subjects. There was a correlation between serum BPA and Epo titers in patients with aplastic anemia and paroxysmal nocturnal hemoglobinuria (r = 0.81, t test, P less than 0.001).

Anemia↗
PubMed1986

In-vitro effects of antineoplastic prostaglandins on human leukemic cell growth and normal myelopoiesis.

The effects of prostaglandin (PG)E1, PGD2 and 9-deoxy-delta 9-PGD2 (PGJ2) on the clonogenic growth of six kinds of human leukemic cell lines (K562, KG1, HL60, U937, THP1 and Molt4) and normal human myeloid progenitor cells (CFU-GM) were studied using semisolid agar cultures. While the degree of suppression of leukemic growth by PGE1 varied from cell line to cell line, PGD2 and PGJ2 equally suppressed the growth of all leukemic cell lines. The potency of growth inhibition was as follows: PGJ2 greater than PGD2 greater than PGE1. The increase of cellular cAMP level induced by prostaglandin treatment did not parallel their cytotoxic potency. Normal myeloid colony formation was also suppressed by PGE1, PGD2 or PGJ2. In contrast to the preferential inhibition of macrophage colony formation by PGE1, such lineage-selective suppression was not observed for PGD2 or PGJ2. These findings suggest that PGD2 and PGJ2 potently inhibit the leukemic growth by a different mechanism from that of PGE1 and by a cAMP-independent mechanism. These prostaglandins seem to be promising chemotherapeutic agents for acute leukemia.

Adenylyl Cyclase Inhibitors↗
PubMed1986

In vitro formation of macrophage-epithelioid cells and multinucleated giant cells by 1 alpha,25-dihydroxyvitamin D3 from human circulating monocytes.

1 alpha,25-Dihydroxyvitamin D3, the active form of vitamin D3, induced maturation of circulating monocytes to form macrophage-epithelioid cells and multinucleated giant cells in vitro. Calcitriol not only promoted the differentiation of monocytes, as shown by the marked morphological changes and enhanced secretion of lysozyme, but also induced their prominent proliferation, as exhibited by enhanced DNA synthesis and the increased number of monocyte cell nuclei. The proliferation of monocytes was observed after the addition of physiological concentrations of calcitriol. Multinucleated giant cells were frequently observed among the monocytes. These marked morphological changes and the proliferation of monocytes were not observed in control cultures, which did not include calcitriol. These results indicate that calcitriol plays a critical role in the formation of the sarcoid granuloma and give an explanation of some of the clinical findings on sarcoidosis. In view of the evidence that sarcoid macrophages convert 25(OH)D3 to calcitriol, our results raise the possibility that the active metabolite of vitamin D3, which may be produced by macrophage-epithelioid cells, induces the differentiation and proliferation of circulating monocytes into macrophage-epithelioid cells, which in turn form sarcoidosis granulomas. This autostimulation mechanism of sarcoid granuloma formation may provide a model for future studies.

Adult↗
PubMed1986

Partial prevention of compactin (ML-236B) inhibition of in vitro hematopoiesis by dolichol and dolichyl phosphate.

We have reported that the exogenous addition of dolichyl phosphate (Dol-P) enhances the colony-forming capacities of early erythroid progenitors (BFU-E), late erythroid progenitors (CFU-E), and granulocyte-macrophage progenitors (CFU-GM) in adult mouse bone marrow, and that dolichol (Dol) enhances that of only CFU-E (Int. J. Cell Cloning 3:313, 1985). Compactin (2.5-10 microM), a specific inhibitor of mevalonate biosynthesis that causes a decrease of endogenous Dol biosynthesis, inhibited colony formation of CFU-GM. Exogenous addition of Dol-P partially prevented this inhibition, but Dol and the other mevalonate metabolites, such as cholesterol, coenzyme Q10, and isopentenyladenine, could not. In addition, we have found that the colony-forming capacity of CFU-E in fetal mouse liver was not enhanced by exogenous Dol or Dol-P. But the decrease of colony formation or DNA synthesis of fetal CFU-E in the presence of compactin was prevented by the exogenous addition of Dol or Dol-P.

Animals↗
PubMed1986

Steatocystoma multiplex. A facial papular variant.

A 32-year-old man had multiple asymptomatic, yellowish to normal skin-colored, moderately firm papules that were disseminated on the forehead, temple, and periauricular region. The histologic, enzyme histochemical, and ultrastructural findings were those of steatocystoma multiplex.

Adult↗
PubMed1985

Induction of alkaline phosphatase in neutrophilic granulocytes, a marker of cell maturity, from bone marrow of normal individuals by retinoic acid.

We examined whether chemical agents reported to induce differentiation of leukemic cells also have differentiating effects on normal human granulocytes using alkaline phosphatase activity as a marker. Among 11 compounds examined, only vitamin A analogues were shown to induce this activity in granulocytes from bone marrow of normal individuals. Retinoic acid was the most potent inducer of the activity followed by retinal, whereas retinol and retinol acetate did not induce any activity. The effect on the alkaline phosphatase activity by retinoic acid and retinal was considered to reflect their effect on normal granulocytic differentiation and maturation.

Alkaline Phosphatase↗
PubMed1985

Microinjection of macromolecules into leukemic cells by cell fusion technique: search for intracellular growth-suppressive factors.

To investigate the intracellular molecular events during leukemic cell proliferation, we have examined the method of ghost-mediated microinjection of macromolecules into leukemic cell line cells (HL-60). Samples were packed into red cell ghosts. Microinjection was performed by the fusion of ghosts and HL-60 cells using the hemagglutinating virus of Japan (HVJ). Fusion rate was about 80-90%, when determined by the injection of FITC-labeled globulins (IgG) or diphtheria toxin fragment A into HL-60 cells. When the nuclear protein extract from normal granulocytes was injected into HL-60 cells, their growth was significantly suppressed. The injection of the nuclear protein extract from HL-60 itself into HL-60 cells did not inhibit their growth. This finding suggests that leukemic cells may be deficient in intracellular regulatory factors which have suppressive activity on cell growth.

Animals↗
PubMed1985

1 alpha,25-Dihydroxyvitamin D3 (calcitriol) stimulates proliferation of human circulating monocytes in vitro.

Previous studies demonstrated that human circulating monocytes can proliferate in vitro when incubated with lectin-induced factor(s) from lymphocytes [(1985) Biochem. Biophys. Res. Commun., in press]. This study shows that human monocytes were induced to proliferate when incubated with 1 alpha,25-dihydroxyvitamin D3 (calcitriol) at physiological concentrations. The optimal dose was about 10 nM. Proliferative activity was examined both by measuring the [3H]thymidine incorporation and by counting cell nuclei. Among other derivatives of vitamin D3, 1 alpha,24R-dihydroxyvitamin D3 and 1 alpha,24R,25-trihydroxyvitamin D3 stimulated mitotic activity of monocytes. Addition of both calcitriol and lectin-stimulated lymphocyte-conditioned medium to the monocyte culture had an additional effect on the mitotic activity of monocytes.

Calcitriol↗