Biomedical subjects

K Higashio

Publications and source records attributed to K Higashio.

At least 55 records · Page 3Linked to original sources

PubMed1998

Hepatocyte apoptosis and hepatic expression of transforming growth factor-beta1 mRNA during involution of hyperplastic rat liver induced by hepatocyte growth factor.

Hepatocyte apoptosis occurs during involution of hyperplastic liver induced by administration of xenobiotic compounds in rats. With this hyperplasia and involution, hepatic transforming growth factor (TGF)-beta1 is reported to be expressed to stimulate hepatocyte apoptosis. In regenerating liver after partial resection showing no hyperplasia, such expression of TGF-beta1 is also seen. However, no hepatocyte apoptosis develops despite the high levels of TGF-beta1. When rats received an intravenous injection of human hepatocyte growth factor at 12 h intervals for 14 days, the hepatic DNA content was increased 12 h after the last injection to 140% of control. This DNA content was significantly decreased at 108 and 180 h after discontinuation of treatment. At 60 h after the last injection, the number of apoptotic bodies positive for nick end-labelling of DNA in hepatocytes was significantly greater in treated rats than in control rats. Hepatocyte apoptosis was also identified electron micrographically. Hepatic TGF-beta1 mRNA levels in treated rats were significantly lower than in control rats at 12 h and then gradually increased towards control levels. We conclude that hyperplastic liver induced in normal rats by hepatocyte growth factor regresses with hepatocyte apoptosis and suppressed hepatic TGF-beta1 mRNA levels.

Animals↗

PubMed1998

Identity of osteoclastogenesis inhibitory factor (OCIF) and osteoprotegerin (OPG): a mechanism by which OPG/OCIF inhibits osteoclastogenesis in vitro.

The morphogenesis and remodeling of bone depends on the integrated activity of osteoblasts that form bone and osteoclasts that resorb bone. We previously reported the isolation of a new cytokine termed osteoclastogenesis inhibitory factor, OCIF, which specifically inhibits osteoclast development. Here we report the cloning of a complementary DNA of human OCIF. OCIF is identical to osteoprotegerin (OPG), a soluble member of the tumor-necrosis factor receptor family that inhibits osteoclastogenesis. Recombinant human OPG/OCIF specifically acts on bone tissues and increases bone mineral density and bone volume associated with a decrease of active osteoclast number in normal rats. Osteoblasts or bone marrow-derived stromal cells support osteoclastogenesis through cell-to-cell interactions. A single class of high affinity binding sites for OPG/OCIF appears on a mouse stromal cell line, ST2, in response to 1,25-dihydroxyvitamin D3. An anti-OPG/OCIF antibody that blocks the binding abolishes the biological activity of OPG/OCIF. When the sites are blocked with OPG/OCIF, ST2 cells fail to support osteoclastogenesis. These results suggest that the sites are involved in cell-to-cell signaling between stromal cells and osteoclast progenitors and that OPG/OCIF inhibits osteoclastogenesis by interrupting the signaling through the sites.

Amino Acid Sequence↗

PubMed1998

Hypocalcemic effect of osteoclastogenesis inhibitory factor/osteoprotegerin in the thyroparathyroidectomized rat.

Osteoclastogenesis inhibitory factor (OCIF), also termed as osteoprotegerin (OPG), is a soluble member of the tumor necrosis factor receptor family. Although OCIF/OPG is shown to inhibit osteoclast formation in vitro and prevent ovariectomy-induced bone loss in vivo, its effect on serum calcium level remains to be determined. In this study we examined the acute effect of OCIF on thyroparathyroidectomized rats whose serum calcium concentrations were raised either by exogenous PTH or 1,25-(OH)2D3. When OCIF was administered at the start of PTH infusion, it attenuated the initial rise in serum calcium. When OCIF was administered into rats with established hypercalcemia, it decreased serum calcium rapidly (within 2 hr) and dramatically. OCIF did not increase urinary calcium excretion. These findings, especially the rapid onset of its hypocalcemic effect, suggest that OCIF not only inhibits the formation of osteoclasts but also affects the function and/or survival of mature osteoclasts at doses used in this study.

Animals↗

PubMed1998

Effects of the deleted form of hepatocyte growth factor on serum hyaluronate levels in rats with liver cirrhosis.

Effects of the deleted form of hepatocyte growth factor (dHGF) on serum hyaluronate levels, an index for liver cirrhosis, were studied in rats. The levels of serum hyaluronate increased in rats with dimethylnitrosamine- or carbontetrachloride-induced cirrhotic liver with prolongation of prothrombin time, which indicates disorder of liver function. Daily intravenous injection of dHGF reduced the elevated serum hyaluronate levels with improvement of the prolonged prothrombin time. These results suggest that the amelioration of hepatic function disorder by dHGF leads to a reduction of the increased serum hyaluronate levels.

Animals↗

PubMed1998

[Osteoclastogenesis inhibitory factor (OCIF)/OPG].

A novel cytokine termed osteoclastogenesis inhibitory factor (OCIF) was purified to homogeneity from conditioned medium of human embryonic lung fibroblasts. OCIF is a heparin-binding basic glycoprotein with Mr of 60 kDa for a monomer and 120 kDa for a homodimer. OCIF specifically inhibits osteoclastogenesis in vitro and increases bone mineral density and bone volume in normal rats. The cloning of OCIF cDNA revealed that OCIF is a soluble member of the tumor necrosis factor receptor (TNFR) superfamily consisting of four cystein-rich domains, two death domain homologous regions (DDHs), and C-terminal basic domain. Mutational analysis of OCIF revealed that N-terminal portion of OCIF consisting of four cystein-rich domains is sufficient to inhibit osteoclastogenesis. OCIF inhibits osteoclastogenesis by binding to the sites expressed on osteoblastic cells and interrupting cell-to-cell signaling between osteoblastic cells and osteoclast progenitors.

Animals↗

PubMed1997

Isolation of a novel cytokine from human fibroblasts that specifically inhibits osteoclastogenesis.

A factor which inhibits osteoclast-like cell formation was found in the conditioned medium of human embryonic lung fibroblasts, IMR-90. The factor, termed osteoclastogenesis inhibitory factor, OCIF, was purified to homogeneity. OCIF is a heparin-binding basic glycoprotein and has been isolated as a monomer with an apparent molecular weight (Mr) of 60,000 and a homodimer with a Mr of 120,000. The N-terminus of OCIF is blocked and the determination of internal amino acid sequences revealed that OCIF has no homology to known proteins. OCIF inhibited in a dose-dependent manner osteoclastogenesis elicited through three distinct signaling pathways stimulated by 1 alpha,25-dihydroxy vitamin D3, parathyroid hormone, and interleukin-11, respectively, in a dose range of 1 to 40 ng/ml (IC50 = 4 to 6 ng/ml). OCIF neither inhibits bone resorption by mature osteoclasts nor exerts any other biological activities. These data strongly suggest that OCIF is a novel cytokine which specifically inhibits osteoclastogenesis.

Acid Phosphatase↗

PubMed1997

Recombinant human hepatocyte growth factor facilitates biliary transport after hepatocyte transplantation in Eisai hyperbilirubinemic rats.

Hepatocyte transplantation may offer an attractive treatment for inborn errors of liver metabolism. However, factor(s) are required as stimuli to induce proliferation of the limited number of hepatocytes transplanted. The Eisai hyperbilirubinemic rat (EHBR) is a Sprague-Dawley (SD) mutant rat with conjugated hyperbilirubinemia. EHBRs have impaired canalicular excretory transport of organic anions, bile acid glucuronide, and sulfate. Recombinant human hepatocyte growth factor (rhHGF) (100 microg/kg) was injected intravenously at 2-hr intervals for 10 hr, immediately and 35 days following the intraportal injection of 1 x 10(7) wild-type SD rat hepatocytes. Serum bilirubin concentrations decreased significantly within 35 days and were maintained at significantly reduced levels for 120 days following transplantation. Biliary excretion was demonstrated by the biliary transport of indocyanine green and sulfobromophthalein sodium into the bile. These results indicate that hepatic transport of bile acid conjugates in EHBRs can be restored by hepatocyte transplantation combined with repeated administration of exogenous rhHGF, in conjunction with functioning of the recipient's excretory biliary system.

Animals↗

PubMed1997

Deleted form of hepatocyte growth factor (dHGF) increases the number of platelets in rats with liver cirrhosis.

The effect of the deleted form of hepatocyte growth factor (dHGF) on thrombopoiesis was studied in rats. When normal rats were injected with dHGF (0.5 mg/kg i.v. twice a day), the number of platelets increased to about 1.5-fold the initial level. In addition, the treatment with dHGF (0.5 mg/kg i.v. twice daily) significantly increased the number of platelets in rats with liver cirrhosis induced by carbon tetrachloride and phenobarbital. When dHGF was given to rats at a dose of 0.05 or 0.5 mg/kg from the beginning of the induction of dimethylnitrosamine liver cirrhosis to day 28, dHGF dose-dependently ameliorated thrombocytopenia and completely prevented it at a dose of 0.5 mg/kg. These results indicate that dHGF may be applicable to the treatment of thrombocytopenia associated with liver cirrhosis.

Animals↗

PubMed1996

Antifibrogenic effect of a deletion variant of hepatocyte growth factor on liver fibrosis in rats.

Hepatic fibrosis, which may lead to cirrhosis, is associated with most chronic liver diseases. Current therapies for hepatic fibrosis are, however, generally ineffective. In this report we assessed the efficacy of the treatment of hepatic fibrosis with a naturally occurring deletion variant of hepatocyte growth factor (dHGF). The administration of dHGF increased liver weight and suppressed the increase of hepatic collagen content in rats treated with dimethylnitrosamine (DMN) to induce hepatic fibrosis. Furthermore, dHGF exerted its mitogenic and antifibrogenic activities even after the liver fibrosis had been established with DMN. Northern blot analysis showed that dHGF suppressed the increase of messenger RNA (mRNA) levels of procollagen alpha 2(I), alpha l(III), alpha 1(IV), transforming growth factor beta 1 (TGF-beta1), desmin (a marker of hepatic lipocytes), and alpha-smooth muscle (sm)-actin (a marker of activated hepatic lipocytes). In addition to suppressing the elevated TGF-beta1, mRNA level in hepatic fibrosis, dHGF had a potent ability to decrease TGF-beta1 mRNA level even in a normal liver. Immunohistochemical analysis revealed that desmin-positive cells and alpha-sm-actin-positive cells were increased in the hepatic fibrosis, whereas neither cells were seen in livers of DMN-treated rats given dHGF. We conclude that dHGF prevents and improves the DMN-induced hepatic fibrosis in rats by reducing mRNA levels of procollagens and TGF-beta1, by inhibiting an activation of hepatic lipocytes, and by stimulating liver regeneration. dHGF may be useful for and applicable to the treatment of fibrosis in chronic liver diseases.

Actins↗

PubMed1996

Amelioration of disordered hepatic protein synthesis by the deleted form of hepatocyte growth factor in models of liver failure in rats.

Because the liver plays an important role in protein synthesis and cholesterol metabolism and reductions in these functions are observed in almost all hepatic disorders, the effects of the deleted form of hepatocyte growth factor (dHGF) on disordered hepatic protein synthesis were studied in various liver-injured rat models using Wistar male rats. In the 70% hepatectomized rats, plasma clotting time was prolonged and the serum level of total protein and the liver protein content were decreased. The treatment of the animals with dHGF (100-500 micrograms kg-1, i.v., twice daily) ameliorated these parameters at 48 or 72 h. The administration of carbon tetrachloride or D-galactosamine to hepatectomized rats induced a marked prolongation of plasma clotting time and hypoproteinaemia. In the animals treated with dHGF (500 micrograms kg-1, i.v., twice daily) these parameters were rapidly reversed compared with those of control groups. In a hepatocellular necrosis model induced by dimethylnitrosamine, the plasma clotting time was extremely prolonged, and liver protein content, serum total protein, albumin, HDL-cholesterol (as an index of lipoprotein) and plasma lecithin-cholesterol acyltransferase activity severely reduced. In this severely injured model, dHGF (5-500 micrograms kg-1, i.v., twice daily for 28 days) dose-dependently prevented the loss of liver protein content and improved the disordered plasma coagulability and serum protein levels. These results suggest that dHGF is useful for ameliorating the disorders in hepatic functions such as protein synthesis.

Animals↗

PubMed1994

Hepatocyte growth factor and its variant with a deletion of five amino acids are distinguishable in their biological activity and tertiary structure.

A naturally occurring splice variant of hepatocyte growth factor (HGF) lacks a 5-amino acid sequence in the first kringle domain. Comparison of HGF and the deletion variant (dHGF) revealed that the deletion significantly altered the biological activities, solubility, and immunological property of HGF. HGF was respectively about 20-, 10-, and 2-fold more potent than dHGF in the stimulation of DNA synthesis in human umbilical vein endothelial cells, human aorta smooth muscle cells, and NSF-60 (murine myeloblastic cells). Conversely, dHGF was respectively about 3-, 2-, and 2-fold more potent than HGF in the stimulation of DNA synthesis in LLC-PK1 (pig kidney epithelial cells), OK (American opossum kidney epithelial cells), and rat hepatocytes. Moreover, HGF was over 70-fold more soluble than dHGF in PBS. Several monoclonal antibodies raised against dHGF recognized only dHGF and neither HGF nor reduced dHGF, demonstrating that the deletion caused a tertiary structural change. The structural change in HGF may be responsible for its altered biological activities and solubility.

Animals↗

PubMed1994

N-glycosylation of erythropoietin is critical for apical secretion by Madin-Darby canine kidney cells.

Erythropoietin (Epo) has three N-linked carbohydrate chains at positions 24, 38, and 83 in its 166-amino acid residues. When the human wild-type Epo was expressed in the polarized Madin-Darby canine kidney (MDCK) epithelial cells, Epo was preferentially secreted from the apical domain. The polarized secretion was perturbed by the treatment of the cells with tunicamycin, suggesting the involvement of N-linked carbohydrate chains in the apical sorting mechanism in MDCK cells. Replacement of asparagine residues at all N-glycosylation sites of Epo with glutamine by site-directed mutagenesis resulted in roughly equal secretion from apical and basolateral domains. Comparative studies on MDCK clones expressing the mutant Epos lacking one or two of the three N-glycosylation sites in every possible combination showed that the N-linked carbohydrate chain at position 38 is critical for the polarized secretion. Nocodazole, a microtubule-disrupting drug, reversed the polarized secretion of the wild-type Epo from the apical to basolateral preference with little change in the total secretion. Hepatocyte growth factor, a scatter factor known to induce the tubule-like structure of MDCK cells, caused almost equal secretion of the wild-type Epo into the apical and basolateral sides, although the tight junctions of MDCK cells remained intact.

Animals↗

PubMed1993

Stimulation of liver growth by exogenous human hepatocyte growth factor in normal and partially hepatectomized rats.

Human hepatocyte growth factor stimulates DNA synthesis by cultured rat hepatocytes. When human hepatocyte growth factor prepared from the culture medium of human embryonic lung fibroblasts was intravenously injected into normal rats and rats after 70% hepatectomy, it was detected in hepatocytes but not in nonparenchymal cells isolated 30 min after injection. Similar injections of human hepatocyte growth factor at 2-hr intervals for 10 hr significantly increased hepatic DNA content in normal rats at 48 hr, with increased hepatic content of putrescine, the essential polyamine for hepatic DNA synthesis after 70% hepatectomy, and activities of catalytic enzymes of putrescine synthesis at 6 hr almost to the levels in rats after 70% hepatectomy. Those levels in rats after 70% hepatectomy were further enhanced by similar injections of human hepatocyte growth factor starting immediately after surgery. Increased hepatic DNA content in normal rats and rats after 70% hepatectomy was also seen with recombinant human hepatocyte growth factor to a greater extent compared with that seen with human hepatocyte growth factor. In normal rats given recombinant human hepatocyte growth factor, 5-bromo-2'-deoxyuridine-labeled and mitotic hepatocytes were significantly increased in number at 26 hr but not at 48 hr. We conclude that exogenous human hepatocyte growth factor acts as a trigger and a promoter of liver growth to increase hepatic putrescine production in rats. Recombinant human hepatocyte growth factor is more potent than human hepatocyte growth factor in this action.

Animals↗

PubMed1993

Tumor cytotoxic activity of HGF-SF.

IMR-90 human embryonic lung fibroblasts secrete a tumor cytotoxic factor. This factor, termed F-TCF, is moderately cytotoxic in human tumor cell lines (KB, MCF-7, BG-1) and is very cytotoxic in mouse tumor cell lines (Sarcoma 180, Meth A sarcoma, P388). The cytotoxicity depends on the initial target cell number and is due to cytostasis rather than cytolysis. F-TCF was purified from conditioned medium by a combination of UF-concentration, CM sephadex C-50, Con A sepharose, Mono S cation-exchange and heparin sepharose chromatography and exhibited a molecular mass (M(r)) of 76 to 80 kD on SDS-PAGE under non-reducing conditions. F-TCF is a heterodimer composed of a large alpha-subunit with M(r) 52 to 56 kD and a small beta-subunit with M(r) 30 to 34 kD. F-TCF is a heparin-binding, heat-labile, basic glycoprotein (pI 7.4-8.6). Its activity is stable over the pH range of 6.0 to 9.0, but is completely lost after reduction with 2-mercaptoethanol. Protein sequencing indicates that the alpha-subunit is blocked at the aminoterminus. The primary amino acid sequences deduced from hepatocyte growth factor (HGF) cDNAs cloned from human placenta and liver cDNA libraries indicate that F-TCF is identical to the placenta type HGF in the aminoterminal sequence of the beta-subunit, but differs at two sites from the liver type HGF. Two forms of F-TCF cDNA were found in an IMR-90 human fibroblast cDNA library. One form was identical to placenta type HGF cDNA and the other was a variant with a 15 base pair deletion in the coding region. In addition, mRNA corresponding to the deleted form of cDNA was present in total RNA prepared from IMR-90 cells. F-TCF was thus identified as placenta type HGFs including a variant. The deleted form of recombinant HGF (rHGF) expressed in CHO cells had slightly lower heparin-binding affinity than did the intact form. Both rHGFs had almost the same dose-response curves for cytotoxicity in Sarcoma 180 or Meth A sarcoma cells. Moreover, rHGF (the deleted form) was cytotoxic in hepatocellular carcinoma cells (HepG2, Hep3B, H35). Dose-response curves for the stimulation of DNA synthesis in rat hepatocytes by HGFs were very similar up to about 12.5 ng/ml, but differed significantly at higher concentrations. The deleted form gave maximal activity in a dose range of 12.5 to 100 ng/ml and had about 1.4- to 1.9-fold higher specific activity in that range than the intact form did.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗

PubMed1992

Possible roles of arachidonic acid and its metabolites in induction of tissue plasminogen activator (t-PA) production in human fibroblast, IMR-90 cells by proteose peptone.

Proteose peptone (p.peptone) had an ability to induce tissue plasminogen activator (t-PA) production by human embryonic lung fibroblast, IMR-90 cells. We previously demonstrated that the induction was closely related to the activation of phospholipase A2 in the cells stimulated by p.peptone. In this report, we describe the involvement of arachidonate metabolism in the induction. The induction was inhibited in a dose-dependent manner by 5,8,11,14-eicosatetraenoic acid (ETYA), an inhibitor of both cycloxygenase and lypoxygenase, and also by nordihydroguaiaretic acid (NDGA), which in low concentrations selectively inhibits lipoxygenase. However, indomethacin, a specific inhibitor of cycloxygenase, had no effect on the induction. 5-hydroxyeicosatetraenoic acid (5-HETE), which is an arachidonate metabolite derived from lipoxygenase pathway, had an inductive effect, but prostaglandin E1 (PGE1), which is a metabolite from cycloxygenase pathway, had no effect on t-PA production by the cells. These results suggest that arachidonate metabolism is involved in the induction of t-PA production in IMR-90 cells by p.peptone, and that arachidonate metabolite(s) from lipoxygenase pathway is responsible for the induction.

Alprostadil↗

PubMed1992

[Structure and biological property of fibroblast-derived tumor cytotoxic factor (F-TCF)].

Fibroblast-derived tumor cytotoxic factor (F-TCF), isolated from human embryonic lung fibroblasts, is cytotoxic against various human and mouse tumor cells. Physicochemical and biological properties indicate that F-TCF is closely similar to hepatocyte growth factors (HGFs), cDNAs of which are isolated from human liver and placenta. Isolation and expression of F-TCF cDNA revealed that F-TCF was identical to the placenta type HGFs, including a variant with a deletion of 15 base pairs in the coding region. The deleted form of recombinant HGF (rHGF) had slightly lower heparin binding affinity than the intact form. Specific activities of rHGFs were almost the same in tumor cytotoxic activity, but different in hepatocyte growth stimulating activity. These results indicate that deletion of five amino acids results in conformational change which alter biological activity.

Amino Acid Sequence↗

PubMed1991

Tumor cytotoxic factor/hepatocyte growth factor from human fibroblasts: cloning of its cDNA, purification and characterization of recombinant protein.

Two different forms of cDNA for F-TCF were isolated from cDNA library prepared with mRNA from human embryonic lung fibroblast, IMR-90 cells. One of them was completely identical to the cDNA for placenta type hepatocyte growth factor (HGF) and the other one was a variant cDNA for the HGF with a deletion of 15 base pairs in the coding region. The cDNAs were expressed in CHO cells and recombinant proteins were purified and characterized. The deleted form of recombinant F-TCF (rF-TCF) was slightly lower in heparin affinity than the intact form. Both rF-TCFs showed almost same dose-response curves for cytotoxicity on Sarcoma 180 or Meth A sarcoma cells. Dose-response curves for the stimulation of DNA synthesis in rat hepatocytes were also almost same before reaching maximal activity at 12.5 ng/ml but significantly different at higher concentrations. The deleted form of rF-TCF maintained maximal activity in the dose range of 12.5 to 100 ng/ml, although the intact form decreased the activity dose-dependently at more than 25 ng/ml. This suggests that the deletion of five amino acids results in a conformational change which alters heparin binding and hepatocyte growth stimulating activities.

Amino Acid Sequence↗

PubMed1991

Participation of phospholipase A2 in induction of tissue plasminogen activator (t-PA) production by human fibroblast, IMR-90 cells, stimulated by proteose peptone.

Proteose peptone (p.peptone) had an ability to induce tissue plasminogen activator(t-PA) production by human embryonic lung fibroblast, IMR-90 cells. The induction was dependent on extracellular Ca2+ concentration. The stimulation of p.peptone caused uptake of 45Ca2+ by the cells. The presences of both p.peptone and Ca2+ in medium were necessary for the continuous induction of t-PA production. Hydrocortisone and dexamethasone inhibited t-PA production induced by p.peptone. In addition, the inhibitors of phospholipase A2, quinacrine and 4-bromophenacylbromide, respectively inhibited t-PA production as well as glucocorticoids. Conversely, melittin, an activator of phospholipase A2, induced t-PA production in a dose-dependent manner. Exogenous phospholipase A2 strongly induced t-PA production and also arachidonic acid moderately did in a dose-dependent manner. P.peptone stimulated the release of radioactive arachidonic acid from 3H-arachidonic acid-labeled IMR-90 cells under the presence of Ca2+. These results suggest that the induction of t-PA production by p.peptone is closely related to the activity of phospholipase A2, that is, the release of arachidonic acid from phospholipids in cell membrane.

Arachidonic Acid↗