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Biomedical subjects

Y Daikuhara

Publications and source records attributed to Y Daikuhara.

At least 37 records · Page 2Linked to original sources
PubMed1996

Liver hepatocyte growth factor does not always correlate with hepatocellular proliferation in human liver lesions: its specific receptor c-met does.

Increased levels of expression of hepatocyte growth factor (HGF) and its specific receptor c-met have been shown in the liver of several benign and malignant pathologies, both in experimental models and humans. We investigated by immunohistochemistry the presence of both HGF and c-met protoocogene product (c-met pp) in 20 hepatocellular carcinomas (HCCs), 5 focal nodular hyperplasias (FNHs), 4 cases of fulminant hepatitis (FH), and 1 case of regenerated liver. The c-met protooncogene product was expressed in all cases with marked overexpression in the HCCs and in ductular metaplasia. HGF was detected in the Ito cells of all cases and in neoplastic hepatocytes of 9 of 20 HCCs (45%). The proliferative index of each lesion was evaluated by means of the polyclonal antibody anti-cyclin A. When the level of expression of HGF and c-met protooncogene product with the percentage of cyclin A+ nuclei were compared, the closest relationship was between c-met protooncogene product and cyclin A+ nuclei were compared, the closest relationship was between c-met protooncogene product and cyclin A. In 11 of 20 HCCs (55%), there wa no correlation between HGF positivity and cyclin A. This seems to suggest that, independently of the levels of native liver HGF, c-met protooncogene product is the most active modulator of liver cell proliferation.

Biomarkers↗
PubMed1996

Hepatocyte growth factor/scatter factor is present in most pleural effusion fluids from cancer patients.

Pleural effusion samples were obtained from 55 patients with malignant disease, including patients with primary lung cancers and those with a variety of other tumours metastatic to the pleura. The effusions were assayed for the presence of hepatocyte growth factor/scatter factor (HGF/SF), by both ELISA and bioassay. The presence of malignant cells in the effusions was also assessed. Detectable amounts of the factor, as judged by both criteria, were found in over 90% of all the effusions, including those from patients with a wide variety of carcinomas and also lymphomas. A wide range of HGF/SF levels were found for all tumour classes, some effusions containing high levels above 4 ng ml-1. It is concluded that tumours within the pleura and adjacent lung tissue are usually exposed to biologically significant levels of HGF/SF.

Carcinoma↗
PubMed1996

Effect of hepatocyte growth factor/scatter factor on lipogenesis in adult rat hepatocytes in primary culture.

Hepatocyte growth factor (HGF)/scatter factor is known to be the most potent mitogen for hepatocytes. In this paper, we report that lipogenesis in primary cultured rat hepatocytes treated with 10 ng/ml of recombinant human HGF (rhHGF) for 24 h was stimulated, as measured by the incorporation of 3H2O into long-chain fatty acids, to more than twice as much as the control. Insulin (0.1 microM) was more effective than rhHGF but rhHGF did not show an additive or synergistic effect when added to insulin. We also showed that treatment with rhHGF increased the activities of glucose-6-phosphate dehydrogenase (G6PDH) and malic enzyme, key enzymes which supply NADPH for lipogenesis, and acetyl-CoA carboxylase, the rate-limiting enzyme of lipogenesis. The increase in G6PDH and acetyl-CoA carboxylase activities was accompanied by increases in the levels of mRNA for the enzymes. These results suggest that HGF is involved in liver regeneration not only by stimulation of cell proliferation but also by acceleration of differentiation of hepatocytes.

Acetyl-CoA Carboxylase↗
PubMed1996

Lipoteichoic acid and interleukin 1 stimulate synergistically production of hepatocyte growth factor (scatter factor) in human gingival fibroblasts in culture.

Lipoteichoic acids (LTA) from various gram-positive bacteria, including oral streptococci such as Streptococcus sanguis, enhanced the production of hepatocyte growth factor (HGF) (scatter factor) by human gingival fibroblasts in culture, whereas lipopolysaccharides (LPS) from various gram-negative bacteria did not. In contrast, LPS induced interleukin 1 activity in human gingival epithelial cells in culture, while LTA had little effect. LTA and recombinant human interleukin 1 alpha enhanced synergistically the production of HGF/SF in human gingival fibroblast cultures. Recombinant human HGF, in turn, enhanced the proliferation of human gingival epithelial cells in culture.

Cells, Cultured↗
PubMed1995

Evidence for the presence of an inactive precursor of human hepatocyte growth factor in plasma and sera of patients with liver diseases.

Human hepatocyte growth factor (hHGF), which is now known to be the same protein as the scatter factor and the tumor cytotoxic factor, is a heterodimeric protein with one heavy chain and one light chain linked together by a disulfide bond, and is thought to be involved in liver regeneration. Using an enzyme-linked immunosorbent assay (ELISA) and Western blot analysis, we found that a significant amount of single chain precursor of hHGF (pro-hHGF) was present in plasma of patients with fulminant hepatic failure (FHF) and that normal human serum contained a protease or proteases that convert pro-HGF to a heterodimeric (mature) form of hHGF. We also showed that the processing protease activity for hHGF was suppressed by such serine protease inhibitors as leupeptin, antipain, and aprotinin, and that sera of patients with liver diseases such as fulminant hepatic failure, acute hepatitis, chronic hepatitis, and cirrhosis contained not only pro-hHGF but also the protease. This is the first report showing the presence of pro-hHGF in human blood, and our observations suggest that hHGF is synthesized and secreted from the hHGF-producing cells as an inactive pro-hHGF after hepatic injuries, and the pro-hHGF is then converted to an active heterodimeric form of hHGF in the blood. It is also suggested that plasma of patients with liver diseases contains an active protease or proteases that convert pro-hHGF to a mature form of hHGF.

Animals↗
PubMed1995

Characterization of biliary epithelial cells isolated from needle biopsies of human liver in the presence of hepatocyte growth factor.

Current methods for the isolation of intrahepatic biliary epithelial cells from human liver rely upon relatively large segments of tissue, thereby limiting studies to cells isolated from patients with end-stage disease. To investigate a greater range of diseases and those at an earlier stage, we have developed a method to isolate biliary epithelial cells from biopsy-sized fragments of human liver. Tissue explants are cultured for > 4 weeks, and, in approximately 50% of samples incubated with medium containing hepatocyte growth factor, biliary epithelial cells begin to migrate from the fragments and proliferate. With time they form confluent pavements of cells that express cytokeratin 19 and gamma-glutamyl transpeptidase and are negative for markers of non-biliary cell phenotype. After subculturing, cells can be expanded, yielding substantial numbers for subsequent study in vitro. Cells can be isolated with a similar degree of success from adult normal liver, from a variety of liver diseases, and from post-transplant liver biopsies. Overall, pediatric tissue yielded cells less frequently than adult tissue. This novel technique is likely to have a major impact on the study of biliary pathophysiology, as small fragments of tissue removed from biopsies taken for diagnostic purposes can be used.

Adolescent↗
PubMed1994

Effects of cytokines and growth factors on phosphorylated fetuin biosynthesis by adult rat hepatocytes in primary culture.

Recently, we showed that a 59 kDa non-phosphorylated sialoprotein purified from rat bone matrix is the rat counterpart of bovine fetuin and human alpha 2-HS glycoprotein and that fetuin synthesized and secreted by adult rat hepatocytes in primary culture is mostly phosphorylated (phosphofetuin), though fetuin is known to contain no phosphorus. Here we report that the rate of synthesis of phosphofetuin by hepatocytes in culture was reduced by inflammatory cytokines such as human interleukin (hIL)-6, human tumor necrosis factor-alpha and hIL-1 alpha, but dose-dependently stimulated by growth factors of hepatocytes, such as hepatocyte growth factor (HGF)/scatter factor (SF), epidermal growth factor and insulin, as determined by metabolic labeling and Northern blot analysis using cDNA for rat fetuin as a probe. We also showed that administration of HGF/SF stimulated gene expression of rat fetuin in vivo.

Animals↗
PubMed1994

Immunohistochemistry with antibodies to hepatocyte growth factor and its receptor protein (c-MET) in human brain tissues.

Hepatocyte growth factor (HGF) is a potent mitogen for mature hepatocytes, and also has multifunctional effects on some other cells in various organs. The human c-Met proto-oncogene product has recently been identified as its high-affinity receptor. We examined HGF-like and c-Met protein-like immunoreactivities in the brains of neurologically normal, lacunar stroke and Alzheimer disease (AD) cases. The HGF antibody stained only round cells in the capillaries and astrocytes in the white matter. Positive staining with the antibody to c-Met protein was seen in microglia, predominantly in the white matter. The possibility of interactions between astrocytes and microglia through HGF and its receptor is suggested.

Aged↗
PubMed1994

Plasma hepatocyte growth factor and biliprotein levels and outcome in fulminant hepatic failure.

Plasma levels of growth factors may be important in determining the extent of liver regeneration in patients with fulminant hepatic failure and in this study human hepatocyte growth factor and biliprotein (bilirubin covalently bound to albumin) were determined in patients with fulminant hepatic failure, mainly as a result of acetaminophen overdose. Admission values for plasma human hepatocyte growth factor were significantly raised, although with a wide range in acetaminophen-induced fulminant hepatic failure (median 7.4 ng/ml, range 0.45-48.4 ng/ml, n = 34) and in fulminant hepatic failure from other causes (3.8 ng/ml, 1.72-25.1 ng/ml, n = 9) as compared to normal subjects (0.24 ng/ml, 0-0.5 ng/ml, n = 30). Higher plasma human hepatocyte growth factor was observed in patients who died (10.1 ng/ml, 3.8-48.4 ng/ml, n = 19) than in those who survived (4.3 ng/ml, 0.45-25.1 ng/ml, n = 22, p < 0.02), which may reflect lack of hepatic clearance in the former group. The median plasma biliprotein on admission (13.2 mg/l, range 6.3-100.7 mg/l, n = 43) was significantly increased compared to normal subjects (1.3 mg/l, 0-4.1 mg/l, n = 7, p < 0.001) with no difference between patients who survived or died, although when plasma biliprotein results were expressed as a percentage of the total bilirubin, the values were slightly higher in survivors (median 14.4%, range 10.8-40.5%, n = 23) compared to those who died (12.1%, 7.7-20.9%, n = 20, p = 0.004).(ABSTRACT TRUNCATED AT 250 WORDS)

Acetaminophen↗
PubMed1994

Expression of hepatocyte growth factor in normal and carbon tetrachloride-treated monkeys.

We examined hepatocyte growth factor-producing organs in normal and carbon tetrachloride-treated Japanese monkeys, a species more related to human beings than rats, by measuring hepatocyte growth factor protein and hepatocyte growth factor mRNA in various tissues. Hepatocyte growth factor protein and hepatocyte growth factor mRNA levels were determined by use of an enzyme-linked immunosorbent assay for human hepatocyte growth factor and Northern-blot analysis using human hepatocyte growth factor cDNA as a probe, respectively. Although very slight amounts of hepatocyte growth factor protein were found in various organs of normal monkeys, the hepatocyte growth factor protein levels were remarkably increased only in the livers and spleens of carbon tetrachloride-treated monkeys. Hepatocyte growth factor mRNA was distinctly detected in the livers, spleens, lungs, intestinal tracts, adrenal glands and aortas of normal monkeys. After the administration of carbon tetrachloride, the hepatocyte growth factor mRNA levels in the liver, spleen and gastrointestinal tract were markedly increased; the level in the lung was unchanged, differing from the findings in rats; and the levels in adrenal gland and aorta were unaltered. These results indicate that the liver is an important hepatocyte growth factor-producing organ in monkeys during liver regeneration and that hepatocyte growth factor induced in the liver may stimulate hepatocyte proliferation by way of a paracrine mode.

Animals↗
PubMed1994

Ultrastructural location of human hepatocyte growth factor in human liver.

Human hepatocyte growth factor has been purified from the plasma of patients with fulminant liver failure, but where this factor is produced in organs or cells of subjects with liver diseases is unknown. Therefore, we used a monoclonal antibody to human hepatocyte growth factor to stain cells in three normal and 29 diseased liver tissues by immunohistochemical techniques. By light microscopy, the immunostained cells seemed to be polymorphonuclear leukocytes because of their segmented nuclei. Some biliary epithelial cells also were stained. Electron microscopy confirmed that the immunostained cells with segmented nuclei were polymorphonuclear leukocytes and that the stained grains were on the membranes of rough endoplasmic reticulum, around specific or azurophilic granules and in the cell sap. Stained grains in the biliary epithelial cells were found sporadically on the inside and outside of the membranes of rough endoplasmic reticulum near the nuclei. Human hepatocyte growth factor is now known to be the same protein as scatter factor and tumor cytotoxic factor, both of which are produced by human fibroblasts in culture, but our results suggest that polymorphonuclear leukocytes in diseased livers are one cellular source of circulating human hepatocyte growth factor. The immunostaining properties of biliary epithelial cells in diseased livers also suggest that the cells produce and secrete human hepatocyte growth factor.

Adult↗
PubMed1993

Enhancement of human hepatocyte growth factor production by interleukin-1 alpha and -1 beta and tumor necrosis factor-alpha by fibroblasts in culture.

Human hepatocyte growth factor (hHGF) was first purified from plasma of patients with fulminant hepatic failure (Gohda, E., Tsubouchi, H., Nakayama, H., Hirono, S., Sakiyama, O., Takahashi, K., Miyazaki, H., Hashimoto, S., and Daikuhara, Y. (1988) J. Clin. Invest. 81, 414-419) and is now identified to be the same protein as the scatter factor (Weidner, K. M., Arakaki, N., Hartmann, G., Vandekerckhove, J., Weingart, S., Rieder, H., Fonatsch, C., Tsubouchi, H., Hishida, T., Daikuhara, Y., and Birchmeier, W. (1991) Proc. Natl. Acad. Sci. U. S. A. 88, 7001-7005) and tumor cytotoxic factor (Shima, N., Nakao, M., Ogaki, F., Tsuda, E., Murakami, A., and Higashio, K. (1991) Biochem. Biophys. Res. Commun. 180, 1151-1158), and it is known to be produced by fibroblasts in culture. Here we report that inflammatory cytokines such as interleukin-1 (IL-1) and tumor necrosis factor (TNF) stimulate production of hHGF from human embryonic lung fibroblasts, MRC-5, and human gingival fibroblasts, GF-5. Recombinant human IL-1 alpha (rhIL-1 alpha) and recombinant human TNF-alpha (rhTNF-alpha) increased hHGF levels in culture supernatants of MRC-5 and GF-5 cells dose-dependently as determined by an enzyme-linked immunosorbent assay for hHGF. The half-maximal stimulatory concentrations of rhIL-1 alpha and rhTNF-alpha were about 1ng/ml and 10 units/ml, respectively. rhIL-1 beta showed almost the same effect as IL-1 alpha on stimulation of production of immunoreactive hHGF from the two cell lines. However, rhIL-6 failed to show the stimulatory effect on hHGF production by the cells in the range of 2-200 units/ml. Human interferon-beta and -gamma also did not show the stimulatory activity. Stimulation of hHGF production was observed 6-12 h after addition of rhIL-1 alpha or rhTNF-alpha and lasted at least 48 h, and the observed stimulation of hHGF production by cytokines was suppressed by addition of corresponding antiserum. hHGF mRNA levels of MRC-5 cells increased by addition of rhIL-1 alpha and rhTNF-alpha in a dose-dependent manner as determined by Northern blot analysis using cDNA for hHGF as a probe. In addition, results from nuclear run-off transcription experiments showed that the two cytokines regulated increasing hHGF gene expression at transcriptional levels rather than a change in mRNA stability. These observations indicate that the inflammatory cytokines modulate the production and secretion of hHGF by fibroblasts and may play an important role for tissue repair and regeneration.

Blotting, Northern↗
PubMed1993

Molecular cloning and sequence analysis of cDNA for a 59 kD bone sialoprotein of the rat: demonstration that it is a counterpart of human alpha 2-HS glycoprotein and bovine fetuin.

A complementary DNA (cDNA) for the 59 kD bone sialoprotein, which is supposed to be the rat counterpart of human alpha 2-HS glycoprotein (alpha 2-HSG) and is synthesized by both hepatocytes and osteoblasts, has been cloned from a rat liver cDNA library. Polyclonal rabbit antibodies to rat 59 kD bone sialoprotein were used to identify and isolate the cDNA. The amino acid sequence of 59 kD bone sialoprotein deduced from the cDNA revealed that the entire protein consisted of 352 amino acid residues, including a signal peptide of 18 amino acid residues, and contained three possible N-glycosylation sites. On Northern blot analysis of rat liver, an mRNA of about 1.5 kilobases was detected. An mRNA of 59 kD bone sialoprotein was also detectable in rat bone but not in other tissues, such as kidney, brain, and lung. A computer search of protein and nucleic acid data bases revealed that 68.2, 63.2, and 97.4% amino acid residues of 59 kD bone sialoprotein were identical with those of human alpha 2-HSG, bovine fetuin, and rat phosphorylated N-glycoprotein (pp63), respectively. The positions of cysteine residues in 59 kD bone sialoprotein also completely matched those in human alpha 2-HSG and bovine fetuin, indicating that the sialoprotein is the rat counterpart of human alpha 2-HSG and bovine fetuin. In addition, comparison of the nucleotide sequence of cDNA for rat fetuin/alpha 2-HSG with that for pp63 recently corrected showed only two differences in nucleotides in the entire protein coding regions of the two proteins, and immunoreactive rat fetuin/alpha 2-HSG in the conditioned medium of adult rat hepatocytes in primary culture was found to be phosphorylated. Thus, because rat fetuin/alpha 2-HSG isolated from bone and synthesized by osteoblasts in culture does not contain phosphorus, it seems to be pp63 dephosphorylated during circulation or in the bone matrix.

Amino Acid Sequence↗
PubMed1993

The role of HGF-SF in animal and human hepatic physiology and pathology.

Hepatocyte growth factor (HGF) was first described as a hepatotrophic factor in partially hepatectomized rat plasma in the early 1980's and was purified from plasma of a patient with fulminant hepatic failure and from rat platelets in 1986-1987. Recent progress has revealed that HGF is the same protein as scatter factor and tumor cytotoxic factor, and is now known to be a broad-spectrum growth factor which stimulates cell growth not only of hepatocytes but also of many other types of epithelial and endothelial cells. In this review, however, we concentrate on the role of HGF, mainly human HGF, on liver regeneration after injury. In humans, plasma levels of hHGF increase to greater than 10 ng/ml during severe liver disease such as fulminant hepatic failure and decrease rapidly to normal levels when the patients recover from the disease. In less severe liver damage such as occurs in acute hepatitis, levels of hHGF in plasma increase to 0.5-1 ng/ml which is approaching the half maximal concentration for the stimulation of DNA synthesis in human hepatocytes in culture. Thus, HGF is believed to be involved in control of liver regeneration. Although the cell type(s) which produces HGF during liver disease is not yet identified, it is possible that circulating leukocytes or splenocytes are responsible. Synthesis of HGF is though to be regulated by a putative inducer(s) derived from damaged liver tissue. A control mechanism for HGF production during liver disease is proposed.

Animals↗
PubMed1992

Effects of protein kinase inhibitors on the mitogenic activity of human hepatocyte growth factor on rat hepatocytes in primary culture.

To evaluate the role of protein phosphorylation reactions in signal transduction of human hepatocyte growth factor (hHGF), now known to be the same protein as the scatter factor and tumor cytotoxic factor, we examined the effects of various inhibitors of protein kinases on the mitogenic activity of hHGF on rat hepatocytes in primary culture. Genistein, a specific inhibitor of tyrosine kinase, dose-dependently inhibited the effect of hHGF in stimulating DNA synthesis of hepatocytes. By contrast, 1-(5-isoquinolinesulfonyl)-2- methylpiperazine (H7), a specific inhibitor of protein kinase C, potentiated the stimulatory effect of hHGF on DNA synthesis of hepatocytes. H7 was effective at over 2 micrograms/ml and potentiated the effect of hHGF over 2-fold at 20 micrograms/ml. On the other hand, an inhibitor of Ca++/calmodulin-dependent protein kinase inhibited both the basal and hHGF-stimulated DNA synthesis in the cells, whereas an inhibitor of cyclic nucleotide-dependent protein kinases had little effect on the action of hHGF. These results suggest that tyrosine phosphorylation is required for stimulation of hepatocyte DNA synthesis by hHGF and that the action of hHGF is negatively regulated by protein kinase C activation.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1992

Identification and partial characterization of two classes of receptors for human hepatocyte growth factor on adult rat hepatocytes in primary culture.

To characterize the receptor(s) for human hepatocyte growth factor (hHGF), a physiological hepatotrophic factor involved in liver regeneration following hepatic injury, recombinant hHGF (rhHGF) was radioiodinated. The labeled rhHGF retained its full biological activity on adult rat hepatocytes in primary culture. The specific binding of [125I]iodo-rhHGF to hepatocytes reached a plateau within 240 min at 4 degrees C. Scatchard plot analysis of the binding data suggested the presence of two classes of high affinity binding sites for [125I]iodo-rhHGF. One of the sites had a dissociation constant (Kd) of about 4.6 pM with 300 sites/cell and the other has a Kd of about 275 pM with 15,160 sites/cell. Unlabeled rhHGF displaced cell surface-bound [125I]iodo-rhHGF in a dose-dependent manner as did native hHGF purified from plasma of patients with fulminant hepatic failure. However, other growth factors to rat hepatocytes in primary culture such as insulin and human epidermal growth factor, and proteins which have high amino acid sequence-homology to hHGF such as plasminogen and prothrombin, did not compete with [125I]iodo-rhHGF in the binding, which suggests the binding was specific to hHGF. Covalent cross-linking experiment of [125I]iodo-rhHGF to cell surface receptor(s) on hepatocytes showed there were two macromolecular species with apparent molecular weights of 330,000 and 230,000. Unlabeled rhHGF and native hHGF competed for the binding of [125I]iodo-rhHGF to the two macromolecular species, but insulin, human epidermal growth factor, plasminogen, and prothrombin did not. Based upon our estimated molecular weight of rhHGF = 84,000, these results suggest that hHGF specifically binds to two polypeptides of 246,000 and 146,000 daltons which are likely to represent the hHGF receptors of primary cultured rat hepatocytes.

Animals↗