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Biomedical subjects

F Takaku

Publications and source records attributed to F Takaku.

At least 253 records · Page 14Linked to original sources
PubMed1990

A novel protein-tyrosine kinase, tec, is preferentially expressed in liver.

To identify protein-tyrosine kinases which play an important role in the process of hepatocarcinogenesis, we have screened a murine liver cDNA library with v-fps kinase domain as a probe. Using low stringency screening, we could isolate cDNAs of a putative protein-tyrosine kinase, tec (tyrosine kinase expressed in hepatocellular carcinoma). Nucleotide sequences of the cDNAs show that the C-terminal domain of its predicted protein has significant homology with that of the members of the src family. The tec gene is expressed mainly in liver and faintly in heart, kidney and ovary. Northern analysis further shows that in 2 out of 4 cell lines of human hepatocellular carcinoma (HCC) the tec gene is highly expressed compared to normal human liver. This is the first report showing a protein-tyrosine kinase which may be specifically involved in the cell growth of hepatocytes or in the step of hepatocarcinogenesis.

Amino Acid Sequence↗
PubMed1990

[Primary pulmonary lymphoma diagnosed by transbronchial biopsy and bronchoalveolar lavage findings].

A 45 year-old male was admitted to Tokyo University Hospital because of a submandibular tumor. Biopsy specimen of the tumor showed medium-sized non-Hodgkin's lymphoma of follicular type and immunoperoxidase staining of frozen sections demonstrated an overwhelming predominance of B lymphocytes with IgM, lambda chain. In the meanwhile, chest X-ray taken on admission showed an ill-defined consolidation with a tumor-like appearance in the right middle lung field. Transbronchial biopsy of this lesion revealed massive infiltrations of small and medium sized lymphocytes, having the same markers as those of submandibular tumor (IgM, lambda chain) and an analysis of bronchoalveolar lavage showed a significant increase of CD19-positive B lymphocytes. Reviewing of check-up X-ray films showed the lung lesion to have preceded the submandibular tumor and to have increased its size in several years. On the basis of the similarity of histological and immunohistochemical findings between pulmonary and submandibular tumor, and considering the time course of the appearance of these tumors, we concluded that these tumors were of the same histological nature and had originated in the lung and metastasized to submandibular gland. This is a relatively rare case of pulmonary lymphoma metastasizing to the submandibular gland, in which transbronchial biopsy specimen and analysis of lymphocytes in bronchoalveolar lavage were helpful in establishing the diagnosis.

Biopsy↗
PubMed1990

Overexpression confers an oncogenic potential upon the eph gene.

The eph gene encodes a putative receptor tyrosine kinase for an as yet unknown ligand. Some human cancer cells have been found to overexpress eph mRNAs without gene amplification. We show here that NIH3T3 cells acquire tumorigenic ability in nude mice and make colonies in soft agar with a viral LTR (Long Terminal Repeat)-driven artificial expression of the eph gene to a high level. This result supports the alleged contribution of overexpressed receptor tyrosine kinases to cell transformation.

Agar↗
PubMed1990

Human ltk: gene structure and preferential expression in human leukemic cells.

We have isolated the human homolog (hltk) of the murine tyrosine kinase gene ltk from a K-562 human leukemia cDNA library. The deduced protein sequence of hltk is 17 amino acids longer in the juxtamembrane domain and 28 amino acids shorter in the carboxy terminus than that of murine ltk. The partially identical splicing points of hltk to those of c-ros showed a close genetic linkage between the two. In Northern blot analysis of 35 human malignancies, hltk is preferentially expressed in leukemias (10 out of 18 cases) with no cell lineage specificity, but none of 17 nonleukemic neoplasms expressed hltk gene.

Amino Acid Sequence↗
PubMed1990

Regulatory mechanisms of erythropoietin levels in dialysis patients.

We described a radioimmunoassay system for measuring blood erythropoietin (Epo) levels using recombinant human Epo and evaluated the regulatory mechanisms of Epo in dialysis patients. A satisfactory dose-response relationship for Epo levels was observed within the wide range of 3-250 mU/ml with a sensitivity of approximately 5 mU/ml. The Epo levels were found to be 16.1 +/- 8.6 mU/ml (m +/- SD) in 422 uremic patients on maintenance dialysis and 17.1 +/- 7.2 mU/ml in 86 normal subjects. The Epo levels were not statistically different between the two groups, although the hematocrit was significantly lower in the dialysis patients. No correlation was observed between the Epo levels and hematocrit in the dialysis patients. Patients with polycystic kidneys had higher hematocrits and Epo levels than patients with chronic nephritis. No changes in Epo levels were observed with age and with the period of dialysis. Diurnal variations in the Epo levels revealed a significant increase after hemodialysis, and an acute reduction in hematocrit following massive hemorrhage raised the Epo levels up to 3,180 mU/ml. These findings indicate that the Epo levels in dialysis patients are inappropriately low for the severity of anemia and suggest that a negative feedback mechanism of the hematocrit on the Epo secretion may exist in uremic patients as well as in normal subjects and that the threshold for Epo secretion might be 'reset' at a low hematocrit level.

Erythropoietin↗
PubMed1989

Gene polymorphism identified by PvuII in familial lipoprotein lipase deficiency.

We previously demonstrated that the PvuII polymorphism is a useful marker to analyze the genetic defects in familial lipoprotein lipase (LPL) deficiency. In this study, we have mapped this polymorphic site and cloned the gene fragments containing this site from a patient and a normal subject. Comparative sequence analysis revealed that a C-T transition occurred in the gene of the patient at the PvuII site in the intron 6. Interestingly, the sequence near the PvuII site showed a significant homology to the consensus sequence of the 3' splice site. In addition, the insertional event into the human LPL gene, which was recently reported for a population of Caucasian patients, was not observed for eight unrelated Japanese patients, suggesting that genetic defects underlying familial LPL deficiency should be heterogeneous among races.

Base Sequence↗
PubMed1989

Developmentally regulated expression of vascular smooth muscle myosin heavy chain isoforms.

Two types of smooth muscle myosin heavy chain (MHC) isoforms, SM1 and SM2, were recently identified to have different carboxyl termini (Nagai, R., Kuro-o, M., Babij, P., and Periasamy, M. (1989) J. Biol. Chem. 264, 9734-9737). SM1 and SM2 are considered to be generated from a single gene through alternative RNA splicing. In this study we investigated expression of vascular MHC isoforms during development in rabbits at the mRNA, protein, and histological levels. In adults, all smooth muscle cells reacted with both anti-SM1 and anti-SM2 antibodies on immunofluorescence, suggesting the coexpression of SM1 and SM2 in a single cell. In fetal and perinatal rabbits, however, only anti-SM1 antibody consistently reacted with smooth muscles. Reactivity with anti-SM2 antibody was negative in the fetal and neonatal blood vessels and gradually increased during 30 days after birth. These developmental changes in SM1 and SM2 expression at the histological level coincided with mRNA expression of each MHC isoform as determined by S1 nuclease mapping, indicating that expression of SM1 and SM2 is controlled at the level of RNA splicing. However, sodium dodecyl sulfate-polyacrylamide gel electrophoresis of myosin from fetal and perinatal aortas revealed the presence of large amount of SM2. Interestingly, fetal SM2 did not cross-react with our anti-SM2 antibody on immunoblotting. We conclude that expression of SM1 and SM2 are differentially regulated during development and that a third type of MHC isoform may exist in embryonic and perinatal vascular smooth muscles.

Animals↗
PubMed1989

Recombinant human granulocyte colony-stimulating factor as an activator of human granulocytes: potentiation of responses triggered by receptor-mediated agonists and stimulation of C3bi receptor expression and adherence.

Recombinant human granulocyte colony-stimulating factor (rhG-CSF) enhanced superoxide release and membrane depolarization in parallel in human granulocytes stimulated by the receptor-mediated agonists, N-formyl-methionyl-leucyl-phenylalanine and wheat germ agglutinin, but not by the Ca2+ ionophore ionomycin and phorbol myristate acetate, which bypass the receptors to stimulate the cells. The optimal effect was obtained by pretreatment of cells with 25 to 50 ng/mL (1.3 to 2.6 nmol/L) rhG-CSF for 10 minutes at 37 degrees C. rhG-CSF produced by bacteria and mammalian cells had identical biological effects on a molar basis. rhG-CSF neither affected stimulus-induced increase in cytoplasmic free Ca2+ nor changed the number and affinity of N-formyl-methionyl-leucyl-phenylalanine receptors. The priming effect of rhG-CSF was temperature dependent and did not require new protein synthesis. rhG-CSF increased the expression of C3bi receptors on human granulocytes and enhanced granulocyte adherence to nylon fiber. The optimal effect was obtained by pretreatment of cells with 25 to 50 ng/mL rhG-CSF for 30 minutes at 37 degrees C. rhG-CSF had no effect on human monocytes. These findings demonstrate that rhG-CSF can selectively stimulate mature granulocyte functions.

Calcium↗
PubMed1989

Enhancing effect of human monocytic colony-stimulating factor on monocyte tumoricidal activity.

Human monocytic colony-stimulating factor (hM-CSF) enhances several effector functions of human peripheral blood monocytes. In this study, we investigated the effect of the Mr 85,000 form of hM-CSF on the tumoricidal activity of human monocytes against several leukemic cell lines using a 12-h chromium release assay. Human peripheral blood monocytes preincubated with hM-CSF for 48 h showed more effective killing activity towards K562, U937, Daudi, and HL60 cells as compared with the cells preincubated with medium alone. Maximal enhancement of the tumoricidal activity was achieved by hM-CSF at concentrations of 50-100 ng/ml. A trace amount of lipopolysaccharide contained in the hM-CSF did not seem to contribute to the enhancing effect, as the addition of a lipopolysaccharide-neutralizing agent, polymyxin B, to the preincubation mixture did not reduce this effect. Anti-tumor necrosis factor antiserum partially blocked the tumoricidal activity mediated by hM-CSF, indicating that tumor necrosis factor may participate in the hM-CSF-mediated increase of monocyte tumor cell-killing activity. These results suggest that in addition to other monocyte-activating factors, hM-CSF augments monocyte tumoricidal activity against a wide spectrum of tumor targets.

Cell Line↗
PubMed1989

Identification of an acidic ribosomal protein reactive with anti-Sm autoantibody.

Autoantibody to Sm Ag is a highly specific marker for the diagnosis of SLE. The Sm Ag exists in the cell nucleus as part of a ribonucleoprotein complex containing five small nuclear RNA. The major immunoreactive Sm species have been reported to be three polypeptides of m.w. 28,000/29,000 (B/B') and 16,000 (D). We report here that a m.w. 21,000 peptide is another major target of anti-Sm antibody. This peptide was originally identified by Western blotting as an acidic ribosomal protein (RP21) reactive with IgG from some SLE patients. Anti-RP21 is distinct from anti-ribosomal P protein antibody (anti-P) which has been previously identified as a lupus-specific autoantibody. Cell fractionation experiments showed that RP21 existed only in the ribosomal fraction and was never detected in other cellular compartments including nuclei. However, when nuclear extracts were used as Ag sources in immunoblotting, affinity-purified anti-RP21 was found to react with m.w. 28,000 and 16,000 peptides, suggesting that anti-RP21 reactivity might be due to the cross-reaction of anti-Sm. This was further confirmed by the evidence that two kinds of murine anti-Sm mAb independently derived from MRL/lpr mouse recognized RP21. These results indicate that anti-Sm antibodies in SLE are reactive with both nuclear and ribosomal ribonucleoproteins. Previous reports have described certain similarities, i.e., antibody subclass restriction and incidence, of anti-Sm and anti-P in both humans and autoimmune mice. Our present study demonstrated a close physical association of target molecules reactive with anti-Sm and anti-P, and might, therefore, provide some clue to the origin of these two types of lupus-specific autoantibodies.

Animals↗
PubMed1989

Paraneoplastic syndrome of hypercalcemia and leukocytosis caused by squamous carcinoma cells (T3M-1) producing parathyroid hormone-related protein, interleukin 1 alpha, and granulocyte colony-stimulating factor.

Previously we reported that a clonal squamous cell carcinoma cell line (T3M-1) derived from a lower jaw cancer of a patient with marked leukocytosis and hypercalcemia produced factors containing a potent bone-resorbing activity (BRA) (Mr 15,000-20,000) and a colony-stimulating activity. To elucidate the pathogenesis of this humoral hypercalcemia, BRA and colony-stimulating activity in both the conditioned medium and cells were characterized. The conditioned medium, when eluted at neutral pH, contained colony-stimulating activity and thymocyte proliferation-stimulating activity, the latter of which comigrated with BRA. Upon elution with acetic acid (pH 2.0), the conditioned medium contained no interleukin 1-like activity but potent parathyroid hormone-like activity, which comigrated with BRA. Northern blot hydridization analysis revealed that T3M-1 cells produced constitutively mRNA for parathyroid hormone-related protein and granulocyte colony-stimulating factor. Furthermore, primer extension analysis revealed that the cells also produced mRNA for interleukin 1 alpha (IL-1 alpha). Since parathyroid hormone-related protein and IL-1 alpha (osteoclast-activating factor) synergistically increase the concentration of serum calcium, and since IL-1 alpha (hemopoietin 1) potentiates granulocyte colony-stimulating factor-induced granulocytopoiesis, we speculate that parathyroid hormone-related protein, granulocyte colony-stimulating factor, and IL-1 alpha are synergistically involved in a paraneoplastic syndrome of hypercalcemia and leukocytosis, at least in some patients with solid tumors.

Animals↗
PubMed1989

Hemodynamic shear stress stimulates endothelin production by cultured endothelial cells.

We have examined the effect of shear stress on the production of endothelin by cultured porcine endothelial cells. Low shear stress stimulated the expression of endothelin mRNA in polygonal endothelial cells with a peak time of 2 to 4 hours and also increased the release of immunoreactive endothelin into the culture medium. The expression of endothelin mRNA in the ellipsoidal endothelial cells under higher shear stress was not different from that of the control level. Our results suggest a possible role for hemodynamic shear stress in the regulation of endothelin production in vascular endothelial cells.

Animals↗
PubMed1989

Characterization of cellular receptors for erythroid differentiation factor on murine erythroleukemia cells.

Erythroid differentiation factor (EDF), which is structurally related to transforming growth factor-beta family and induces differentiation of murine erythroleukemia cell clone F5-5, has been labeled with 125I to characterize its interaction with cellular receptors. Binding of 125I-EDF to F5-5 cells is time- and temperature-dependent, specific, saturable, and reversible. Transforming growth factor-beta 1 has no significant effects on growth of F5-5 cells and binding of 125I-EDF to F5-5 cells. Scatchard analysis of the binding data indicated that F5-5 cells have a single class of binding sites (3,200/cell) with an apparent Kd of 3.1 X 10(-10) M. Affinity cross-linking experiments demonstrated three radiolabeled components of 140,000, 76,000, and 67,000 daltons under both reducing and nonreducing conditions. Labeling of these three components has been inhibited by incubation of the cells with excess unlabeled EDF. These results imply molecular weights of 115,000, 51,000, and 42,000 for the EDF receptors on this cell line.

Activins↗
PubMed1989

Characterization of human interleukin-3 receptors on a multi-factor-dependent cell line.

Recombinant human interleukin-3 (hIL-3) was radioiodinated by Bolton-Hunter method with maintenance of biological activity. Using 125I-hIL-3, hIL-3 receptors were characterized on a multi-factor-dependent cell line TF-1. Equilibrium binding studies revealed the existence of a single class of binding sites (667 +/- 306 sites/cell) with a Kd of 173 +/- 25 pM. Affinity labeling of TF-1 cells with 125I-IL-3 yielded two bands of 150 kDa and 85 kDa, implying molecular weights of 135 kDa and 70 kDa for the hIL-3 receptors.

Cell Line↗