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T Tokiwa

Publications and source records attributed to T Tokiwa.

At least 19 recordsLinked to original sources
PubMed2000

The in vitro differentiating capacity of nonparenchymal epithelial cells derived from adult porcine livers.

Specific nonparenchymal epithelial cell (NPEC) clusters derived from normal adult porcine livers demonstrate a characteristic developmental pattern in the presence of other types of nonparenchymal cells in vitro. This pattern includes scattering, colonial growth, and an emergence of duct-like structures (DLSs) in the colonies. It has been confirmed that 96% of the scattered cell clusters in these cultures develop into colonies containing DLSs. In this study, we examine the differentiation of NPEC clusters using the scattered formation as a marker of the DLS-emerged colonies. We report that the NPECs expressed albumin, alpha-fetoprotein, transferrin, cytokeratin (CK) 18, CK7, and c-met, but not alpha-1-antitrypsin (AAT), at the scattering stage. In addition, at the same stage, NPECs expressed oval-cell-related markers such as OV6, but not biliary epithelial cell (BEC) markers such as gamma-glutamyltransferase, CK19, and CK14. At the DLS emerging stage, hepatocyte markers, including AAT, were detectable in the cells either at the periphery of colonies or in the cells surrounded by the DLSs. On the other hand, the cells constituting DLSs expressed BEC markers, suggesting a bile duct nature of the DLSs. Furthermore, the cells in the colonies possessed an ultrastructural appearance of differentiated hepatocytes and BECs. These results suggest that certain NPECs are bipotent, and that, in culture, they mimic hepatoblast development in vivo.

Animals↗
PubMed1999

A mild transient decrease of peripheral red blood cell counts induced by a suprapharmacological dose of pegylated human megakaryocyte growth and development factor in rats.

Previous studies have shown that pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF) at suprapharmacological dose induces a mild transient decrease of red blood cell counts according to thrombopoiesis in normal mice. To unravel the mechanism underlying this mild transient decrease of red blood cells, we have studied the effect of PEG-rHuMGDF on the circulating plasma and blood volume, and the serum biochemical parameters of anaemia and splenectomy. Also, we have performed histological studies of the bone marrow and the spleen of PEG-rHuMGDF-treated rats. PEG-rHuMGDF (300 microg kg(-1)]) or vehicle was subcutaneously administered to rats once a day for up to five days. From day 6 after the start of PEG-rHuMGDF administration, the platelet counts and plateletcrit levels were significantly increased, reaching peak values on day 10, and recovering to normal by day 20. The red blood cell counts and the haematocrit levels were significantly decreased on day 6 to 13. The decreases in red blood cell levels and haematocrit produced by PEG-rHuMGDF treatment were mild and had recovered by day 15. The plasma and blood volumes were significantly increased on day 10 in PEG-rHuMGDF-treated rats. No alteration of the serum biochemical parameters for anaemia, iron or total bilirubin, were observed on day 10. The histological examination on day 10 revealed a marked increase in megakaryocytes and a slight decrease in erythropoiesis in the bone marrow of rats that received PEG-rHuMGDF (300 microg kg(-1)). There was also a slight increase in splenic megakaryocytes and erythropoiesis. The decrease of red blood cells by PEG-rHuMGDF was not affected by splenectomy. These results suggest that the mild transient decrease of red blood cells induced by PEG-rHuMGDF treatment for up to five days is based mainly on the increases in the plasma and blood volume. These events are secondary changes due to the regulation of the excess production of megakaryocytes in the marrow and the peripheral platelets.

Anemia↗
PubMed1998

Effects of KRN4884 (a novel K+ channel opener), levcromakalim, nilvadipine and propranolol on endothelin-1-induced heart disorders in anesthetized rats.

The effects of KRN4884 (5-amino-N-[2-(2-chrolophenyl)ethyl]-N'-cyano-3-pyridinecarboxa midine), a novel K+ channel opener, on the electrocardiogram changes caused by the intracoronary administration of endothelin-1 (ET-1) were studied in anesthetized rats and compared with the effects of levcromakalim, a K+ channel opener; nilvadipine, a Ca2+ antagonist; and propranolol, a beta-adrenoceptor antagonist. KRN4884 (50 microg/kg, i.v.) and levcromakalim (300 microg/kg, i.v.) inhibited the ST segment elevation and the development of arrhythmias induced by ET-1 (5 microg, i.c.) and decreased the incidence of death. Nilvadipine (300 microg/kg, i.v.) and propranolol (1000 and 3000 microg/kg, i.v.) each prevented the ST segment elevation, but the suppressions of the occurrence of arrhythmias produced by nilvadipine and propranolol were less than that shown by KRN4884. KRN4884 (30 and 50 microg/kg, i.v.), levcromakalim (100 and 300 microg/kg, i.v.) and nilvadipine (100 and 300 microg/kg, i.v.) significantly decreased the mean blood pressure in a dose-dependent manner, but propranolol did not. The heart rate was decreased by nilvadipine (100 and 300 microg/kg, i.v.) and propranolol (1000 and 3000 microg/kg, i.v.), but was not affected by KRN4884 (30 and 50 microg/kg, i.v.) or levcromakalim (100 and 300 microg/kg, i.v.). These results suggest that pretreatments with KRN4884 and levcromakalim are more effective on ET-1-induced electrocardiogram changes than those with nilvadipine and propranolol.

Anesthesia↗
PubMed1998

Colonial growth and differentiation of epithelial cells derived from abattoir adult porcine livers.

The parenchymal cell fraction was isolated from abattoir adult porcine livers and cultured in Dulbecco's Modified Eagles' medium/Ham's F12 medium (DMEM/F12; 1:1) medium supplemented with 5% foetal calf serum, 10 ng/mL glucagon, 10 microg/mL insulin, 60 ng/mL hydrocortisone and eight other factors (NAIR-1 medium). The fraction contained a number of epithelial cells other than hepatocytes, some of which attached to the culture plates as cell clusters and began to grow after 3 days in culture. These epithelial cells growing as colonies were found to express cytokeratin 18 by immunocytochemistry. After 7-8 days, duct-like structures emerged in the central parts of the colonies. The cells constituting the duct-like structures and some cells located outside the structures were positive for cytokeratin 19 and gamma-glutamyltransferase (GGT). The albumin-positive cells were located in the outer parts of the colonies rather than their central parts. Albumin was also detectable in the cells surrounded by the duct-like structures. Moreover, cytochrome P450 IA1 was induced by 3-methylcholanthrene (3-MC) on day 16. These results suggest that porcine liver epithelial cell clusters may contain stem-like cells which can differentiate into mature hepatocytes or bile duct epithelial cells.

Albumins↗
PubMed1997

The role of transforming growth factor-beta in PEG-rHuMGDF-induced reversible myelofibrosis in rats.

Pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF) injected at a suprapharmacologic dose (100 microg/kg) daily for 5 d in normal rats caused marked increases in marrow megakaryocytes and platelet counts at 6-8 d followed by gradual decreases to control levels at 10-20 d. Interestingly, in addition to the expected thrombopoiesis, PEG-rHuMGDF was associated with myelofibrosis with a predominance of reticulin fibres at day 10 followed by complete normalization by day 20. At 6-8 d, the levels of transforming growth factor-beta1 (TGF-beta1) in the extracellular fluid of the marrow, the platelet poor plasma, and the platelet extract were increased 23-, 7- and 2-fold, respectively. The elevated levels of TGF-beta1 were gradually reduced to baseline levels at 13-20 d in accordance with the normalization of myelofibrosis and thrombopoiesis. An ultrastructural analysis showed that large fragments of megakaryocytes were deposited in the marrow parenchyma of PEG-rHuMGDF-treated rats at day 6. PEG-rHuMGDF administration at pharmacologic doses (1 and 10 microg/kg) did not induce the deposition of reticulin fibres in the marrow. These findings suggest that TGF-beta1 leaked from megakaryocytes is involved in the development of the PEG-rHuMGDF-induced myelofibrosis and that this is a reversible process related to the regulation of the excess production of platelets.

Animals↗
PubMed1996

Comparative pharmacokinetics of KRN8602, a new morpholino anthracycline, and adriamycin in tumor-bearing mice.

It has been reported that KRN8602 shows antitumor effects similar or superior to those of Adriamycin (ADM) against several murine and human cell lines and has been found to be effective against multidrug resistant tumor cells. We investigated the pharmacokinetics of KRN8602, a new morpholino anthracycline, in comparison with ADM in mice bearing colon26 adenocarcinoma. After intravenous administration, both drugs disappeared triexponentially from the plasma and KRN8602 was eliminated faster than ADM. The rate of elimination of KRN8602 from tissues was also faster than than of ADM. The relative order of the area under the curve (AUC) of KRN8602 was spleen > tumor > small intestine > lung > kidney > heart > liver > brain > plasma, while that of ADM was spleen > kidney > lung > liver > heart > small intestine > tumor > plasma. ADM was not detectable in the brain. The AUC of KRN8602 was higher than that of ADM in the tumor and brain, but it was lower in other tissues. The tissue-to-plasma concentration ratio (KPapp) of KRN8602 was higher than that of ADM in the tumor, spleen, small intestine and brain. KRN8602 was metabolized to several metabolites. The concentrations of M1 and M2 (glycoside-type metabolites) was relatively high in the spleen. M3 (aglycone-type metabolite) showed a very high AUC ratio in the liver (34%). In tumor, M1 and M2 concentrations were low and M3 was not detected. KRN8602 had a greater activity than ADM and M2 had a cytotoxic activity similar to KRN8602 against colon26 cells in an MTT assay. These results suggest that the strong antitumor effect of KRN8602 against colon26 is due not only to its strong cytotoxic activity but also to its marked transferability into tumors. KRN8602 shows better selective toxicity than ADM, because KRN8602 is more selective for tumors than ADM and less is transferred to normal tissues.

Adenocarcinoma↗
PubMed1996

Interferon-gamma promotes the survival and Fc epsilon RI-mediated histamine release in cultured human mast cells.

We examined the effects of interferon-gamma (IFN-gamma) on 100% pure human mast cells generated in suspension cultures of umbilical cord blood mononuclear cells in the presence of stem cell factor (SCF) and interleukin-6 (IL-6). When mast cells were suspended in serum-free medium without any cytokine after the withdrawal of SCF and IL-6, they died over a period of 5 days because of apoptosis. IFN-gamma in the cultures suppressed apoptosis and prolonged their survival in a dose-dependent manner. This survival-promoting effect of IFN-gamma was blocked by neutralizing antibodies to IFN-gamma or to IFN-gamma receptor (IFN-gamma R). When mast cells were incubated with IFN-gamma in serum-free medium for more than 4 hr during sensitization, immunoglobulin E (IgE)/anti-IgE antibody-induced histamine release was effectively enhanced. Polymerase chain reaction (PCR) amplification of the alpha-chain of IFN-gamma R (IFN-gamma R alpha) yielded products of the correct size predicted from the sequence of the receptor. In addition, flow cytometry using anti-IFN-gamma R monoclonal antibodies (mAbs) indicated that these mast cells bear IFN-gamma R on their surface. These findings suggested that IFN-gamma activates human mast cells via specific receptors in certain aspects of inflammatory reactions.

Antibodies↗
PubMed1995

Effects of T-helper 2-type cytokines, interleukin-3 (IL-3), IL-4, IL-5, and IL-6 on the survival of cultured human mast cells.

Although stem cell factor (SCF) has been identified as a critical cytokine for the development of human mast cells from their progenitors, the effects of other cytokines on human mast cells are less well understood. We examined the effects of several cytokines on the survival of human mast cells of 100% purity generated in suspension cultures of umbilical cord blood mononuclear cells in the presence of 100 ng/mL recombinant human (rh) SCF and interleukin-6 (IL-6). Mast cells suspended in conventional serum-containing medium died over a period of 2 to 6 days after the withdrawal of SCF and IL-6. The cells became pyknotic and underwent DNA fragmentation characteristic of apoptosis. The addition of SCF, IL-3, IL-4, IL-5, or IL-6 to the cultures in both serum-containing and serum-free medium prolonged their survival in a dose-dependent manner. Some other cytokines, such as IL-2, IL-9, IL-10, IL-11, tumor necrosis factor-alpha, transforming growth factor-beta 1, and nerve growth factor, had no survival-promoting effect at 100 ng/mL. Preincubation of mast cells with SCF, IL-4, IL-5, or IL-6 for 24 hours during sensitization with IgE enhanced IgE/anti-IgE antibody-induced histamine release from mast cells, whereas IL-3 showed a negligible effect. Polymerase chain reaction amplification of alpha-chains of IL-3 receptor (R), IL-4 R, IL-5 R, and IL-6 R yielded products of the correct size predicted from the sequence of each receptor. The binding assay using 125I-labeled IL-3 indicated that these mast cells bear receptors for IL-3. These findings suggest that IL-3, Il-4, IL-5, and IL-6, which are mainly produced by T-helper 2 lymphocytes, might regulate the functions of human mast cells in vivo via specific receptors in allergic reactions.

Antibodies, Anti-Idiotypic↗
PubMed1993

p53 gene mutation and integrated hepatitis B viral DNA sequences in human liver cancer cell lines.

A G:C-->T:A mutational hotspot at codon 249 of the p53 tumor suppressor gene has previously been identified in hepatocellular carcinoma (HCC) of patients from Qidong, China and southern Africa in which aflatoxin B1 (AFB1) and hepatitis B virus (HBV) are known synergistic risk factors. We have examined p53 mutation patterns of HCC from geographic areas in which the risk factors vary. Nine HCC lines and four hepatoblastoma lines (HB) were examined for p53 gene mutations and the relationship with HBV infection. Five of the nine HCC lines had homozygous mutation or deletion randomly distributed in exons 6-8, whereas none of the four HB cell lines had p53 mutations. One of the four HB lines (HepG2) had an N-ras mutation at codon 61 position 2. The p53 point mutations in the three HCC cell lines from Japan resulted in the amino acid changes of cysteine for tyrosine in cell line HuH 7 at codon 220 (A:T-->G:C), alanine for glycine in cell line HLF at codon 244 (G:C-->C:G), and serine for arginine in cell line HLE at codon 249 (G:C-->C:G). In addition, the deletion of 18 base pairs from codon 264 position 3 to codon 270 position 1 has resulted in the deletion of Leu-Gly-Arg-Asn-Ser-Phe from the amino acids sequences 256-270 in the Japanese cell line HuH 4. The cell line PLC/PRF/5 that showed p53 mutation at codon 249 (G:C-->T:A) with substitution of serine for arginine was derived from a South African patient. Our results indicate that whereas the p53 gene is not mutated in the HB cell lines, the HCC cell lines frequently contain an abnormal p53 gene. In addition, p53 point mutations were not detected in the four Japanese HCC cell lines that were positive for genomic integration of HBV X-gene and surface antigen gene. The three Japanese HCC cell lines with p53 mutations did not contain HBV sequences, indicating that hepatocarcinogenesis associated with p53 mutation does not require the genomic integration of HBV sequences.

Base Sequence↗
PubMed1992

Primary culture of liver cancer tissues with or without transcatheter arterial embolization and establishment of a cell strain.

More epithelial-like cells are found in primary cultures of transcathetel arterial embolization (TAE)-untreated human liver cancer tissues than in those of TAE-treated tissues. A new cell strain, HUH-33, established from the former, grows slowly and is untransplantable into nude mice and secretes alpha-fetoprotein, albumin and some other tumor markers. Chromosome numbers are widely distributed. HUH-33 expresses hepatocyte type keratin and contains desmosome- or intermediate filament bundle-like structures.

Aged↗
PubMed1990

Influence of renal and hepatic failure on the pharmacokinetics of recombinant human granulocyte colony-stimulating factor (KRN8601) in the rat.

The pharmacokinetics of recombinant human granulocyte colony-stimulating factor (rhG-CSF) was studied in rats experiencing renal and hepatic failure. The serum concentration of rhG-CSF after i.v. administration to male Sprague-Dawley rats at a dose of 10 micrograms/kg was investigated by a sandwich enzyme immunoassay. Total-body clearance of rhG-CSF was 44.48 ml/h/kg in sham-operated rats compared with 9.429 ml/h/kg in bilaterally nephrectomized rats. In sham-operated rats, the half-life (beta) of rhG-CSF was 1.512 h, and it increased to 5.333 h after nephrectomy. The volumes of distribution were identical in both rats. In rats with acute renal failure induced by uranyl nitrate, the clearance and volume of distribution were identical to those of control rats, but the half-life (beta) was slightly shorter. In partially (70%) hepatectomized rats, the clearance of rhG-CSF decreased from 42.08 ml/h/kg to 31.93 ml/h/kg. Similar half-lives were observed in rats in both the sham-operated and hepatectomized groups. However, the volume of distribution decreased after hepatectomy. In rats with hepatic failure induced by CCl4, the pharmacokinetic changes were similar to those observed in hepatectomized rats. These results suggest that renal clearance makes a major contribution to total-body clearance compared with hepatic clearance.

Animals↗
PubMed1990

Cytokeratin expression in human cell lines derived from liver tumors.

Immunohistochemical staining of cell lines derived from human liver tumours showed that five cell lines derived from hepatocellular carcinoma (HCC) and hepatoblastoma were stained positively with monoclonal keratin antibodies, CK-5 (Ker-18-specific) and KL-1 (broad specificity), but not with CK-7 (Ker-7-specific). On the other hand, four carcinoma cell lines derived from the biliary system were stained positively with not only CK-5 and KL-1, but also CK-7.

Albumins↗
PubMed1990

Effects of laminin and collagen type I on the morphology and secretion of proteins in human hepatoblastoma and hepatoma cell lines.

The effects of laminin (LAM) and collagen type I (C-I) on human hepatoblastoma (HuH-6) and hepatoma (HuH-7) cell lines were investigated. C-I was superior to LAM in supporting the attachment of the cells, especially of HuH-6, to plastic surfaces. No effect of LAM and C-I on cellular morphology was recognizable by phase contrast microscopy. By scanning electron microscopy (SEM), much more microvilli were found on the cell surface of HuH-6 on LAM substrate than on C-I substrate. In HuH-7 cells, however, these microvilli were rarely found on either LAM substrate or C-I substrate. The gel profile of the proteins secreted by HuH-6 and HuH-7 cells was not affected by the culture substrate except for the major band, though the amount of alpha-fetoprotein (AFP) secreted was larger when the cells were cultured on LAM substrate than on C-I substrate. These results indicate that the ability of LAM or C-I to enhance attachment is different from that to enhance AFP production or microvilli expression in HuH-6 cells and probably in HuH-7 cells.

Carcinoma, Hepatocellular↗
PubMed1990

Pharmacokinetics of recombinant human granulocyte colony-stimulating factor studied in the rat by a sandwich enzyme-linked immunosorbent assay.

A sandwich enzyme-linked immunosorbent assay for the measurement of recombinant human granulocyte colony-stimulating factor (rhG-CSF) in rat serum was developed using anti-rhG-CSF Fab'-horseradish peroxidase conjugate. This assay method measured rhG-CSF in rat serum with greater sensitivity than a bioassay. Also, a good agreement between enzyme-linked immunosorbent assay and bioassay was observed with rat serum samples after administration of rhG-CSF. The pharmacokinetics of rhG-CSF were investigated in male Sprague-Dawley rats using enzyme-linked immunosorbent assay at four different doses from 1 to 100 micrograms/kg. For i.v. administration, the serum rhG-CSF concentration-time curves were best described by a biexponential equation. Over the dose range studied, no changes in volume of distribution were observed. However, a reduction in rhG-CSF clearance and prolongation of half-life (beta) were noted as the dose of rhG-CSF increased. For s.c. administration, a markedly lower serum peak rhG-CSF concentration was observed, but after 2 to 3 hr, rhG-CSF concentration was higher than that following i.v. administration. Administration s.c. also caused nonlinear increases in the serum concentration. Bioavailability after s.c. administration was 0.509 to 0.704.

Animals↗