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Biomedical subjects

T Okabe

Publications and source records attributed to T Okabe.

At least 325 records · Page 18Linked to original sources
PubMed1988

[Colony-stimulating factors in cancer chemo- and radiotherapy].

Recombinant human granulocyte colony-stimulating factor (Re Hu G-CSF) was prepared and its stimulating effect on granulocytopoiesis was examined in mice. Human G-CSF was purified to homogeneity from conditioned media of a G-CSF-producing cell line. The amino-terminal sequence was determined. By using oligonucleotides as probes, determined by the amino acid sequence, a cDNA library prepared from human macrophages was screened. The cloned G-CSF cDNA was expressed in E. coli K12MM294, and the mature protein was purified to homogeneity. Mice were given intraperitoneal injections of Re Hu G-CSF every day for 14 days. Peripheral blood granulocyte counts were examined 4, 8, 12 and 14 days after injection. Mice were sacrificed on the 14th day for histologic examinations of the bone marrow and spleen. Granulocyte counts began to increase on the 4th day and reached about 80,000/mm3 on the 14th day. Cells of granulocyte lineage were markedly increased in the bone marrow and spleen. Granulocyte precursors (CFU-C) were remarkably increased in the spleen. When mice were treated with 5-fluorouracil, cyclophosphamide or irradiation, the period of granulocytopenia was significantly shortened by subcutaneous injection of Re Hu G-CSF. These results suggest that human G-CSF play a central role in granulocyte production in vivo. The ability of Re Hu G-CSF to stimulate granulocyte production implies that this factor will be clinically useful in neutropenic patients treated with anti-cancer agents or irradiation.

Agranulocytosis↗
PubMed1988

Synergistic effect of dolichyl phosphate and human recombinant granulocyte colony-stimulating factor on recovery from neutropenia in mice treated with anti-cancer drugs.

Severe hematopoietic injury in mice was induced by using either 5-fluorouracil, adriamycin, mitomycin C, or vinblastine. Daily subcutaneous administration of purified human recombinant granulocyte colony-stimulating factor (rG-CSF; 0.3-10.0 micrograms/day) markedly accelerated recovery from the drug-induced granulocytopenia in a dose-dependent manner, as reported previously. On the other hand, daily intraperitoneal administration of dolichyl phosphate (Dol-P) also enhanced granulopoiesis to accelerate recovery from granulocytopenia, although the effect of Dol-P was relatively moderate as compared with that of rG-CSF. A synergistic recovery of granulopoiesis was observed when Dol-P was administered together with rG-CSF to the mice treated with anti-cancer drugs. Joint use of Dol-P (1 mg/day) and rG-CSF (0.3 micrograms/day) was as effective as a higher dose of rG-CSF (3 micrograms/day). Joint use of Dol-P (1 mg/day) and rG-CSF (3 micrograms/day) was sometimes more effective.

Agranulocytosis↗
PubMed1988

[Application of monoclonal antibodies to diagnosis and treatment of small cell lung cancers].

Recently we developed monoclonal antibodies against small cell lung cancer (SCLC) and applied them for diagnosis using histology and imaging, and treatment using SCLC transplanted into nude mice. One monoclonal antibody designated TFS-2 is cytotoxic to SCLC cells with complement. This antibody seems to be useful for purging tumor cells from the bone marrow in vitro when autologous bone marrow transplantation is applied. The other monoclonal antibody, TFS-4, has a high specificity to SCLC. This antibody was useful for diagnosis of SCLC using histology, and for the detection of metastatic tumor cells in the bone marrow. It was possible using imaging by radioisotope-labelled TFS-4 to reveal the localization of SCLC transplanted into nude mice. As for treatment with TFS-4, we injected 500 mu Ci of 131I-labeled TFS-4 into nude mice bearing SCLC, and recognized a reduction in tumor size of about 60%.

Animals↗
PubMed1987

Purification and properties of an endothelial cell growth factor from human platelets.

An endothelial cell growth factor has been purified about 1,000,000-fold to homogeneity from human platelets by a seven-step procedure. The purified product has an apparent Mr on sodium dodecyl sulfate-polyacrylamide gels of 45,000. The mobility in sodium dodecyl sulfate gel electrophoresis was similar in the presence or absence of reducing agents, indicating that the factor consists of a single polypeptide chain. Maximal stimulation by the purified protein was achieved at a concentration of about 20 ng/ml (440 pM). Heparin did not potentiate the activity, nor did the factor bind to heparin immobilized on Sepharose. The purified factor was heat- and acid-labile; it was active on porcine and human endothelial cells, but not on human foreskin fibroblasts. Chromatofocusing revealed that the pI of the factor was 4.6. The structural and functional characteristics of the platelet-derived endothelial cell growth factor are distinct from previously characterized endothelial cell mitogens with affinities for heparin.

Animals↗
PubMed1987

Identification of a new 84/82 kDa calmodulin-binding protein, which also interacts with actin filaments, tubulin and spectrin, as synapsin I.

A new 84/82 kDa calmodulin-binding protein, which also interacts with actin filaments, tubulin and spectrin, was purified from the bovine synaptosomal membrane. The binding of calmodulin to this protein was Ca2+-dependent, and was inhibited by trifluoperazine, the association constant being calculated to be 2.2 X 10(6) M-1. Maximally, 1 mol of calmodulin bound to 1 mol of the purified protein. This protein was phosphorylated by both kinase II (Ca2+- and calmodulin-dependent kinase) and cyclic AMP-dependent kinase. In addition, antibody against this protein was demonstrated to have an immunological crossreactivity with synapsin I in the synaptosomal membrane.

Actins↗
PubMed1987

Isolation of small cell lung cancer-associated antigen from human brain.

Previous studies have demonstrated that monoclonal antibody TFS-4 recognizes a cell surface antigen with a molecular weight of 124,000 expressed selectively on small-cell lung cancer but not on non-small-cell lung cancers and that it cross-reacts with human brain. The antigenic determinant on small-cell lung cancer and that on brain shared common characteristics, i.e., trypsin sensitivity, heat lability, and neuraminidase resistance, suggesting that they are similar peptides (T. Okabe et al., Cancer Res., 44: 5273-5278, 1984; J-i. Watanabe et al., Cancer Res., 47:826-829, 1987). In order to elucidate the nature of this unique antigen recognized by TFS-4, we have purified the antigen to homogeneity from human brain. The antigen was solubilized from brain with 0.5% Nonidet P-40, precipitated with 50% ammonium sulfate, and subsequently purified by sequential chromatographies, i.e., diethylaminoethyl-Sepharose ion exchange, immunoaffinity, and gel permeation high-pressure liquid chromatography. The antigenic reactivity was assessed by immunoblotting using TFS-4 as a primary antibody. The purified antigen showed a single protein band with a molecular weight of 124,000 on sodium dodecylsulfate-polyacrylamide gel electrophoresis detected by a silver staining technique. The results suggest that the antigen on brain tissues is structurally related to the molecule expressed on small-cell lung cancer.

Antibodies, Monoclonal↗
PubMed1987

Monoclonal antibody that distinguishes small-cell lung cancer from non-small-cell lung cancer.

To examine whether a monoclonal antibody, TFS-4, can distinguish small-cell lung cancer from non-small-cell lung cancers, an extensive survey of fresh lung tumors, cancers from other organs, and normal tissue specimens has been carried out. The antibody has been shown to react specifically with small-cell lung cancer (15 of 15) but not with squamous cell carcinoma (0 of 20), adenocarcinoma (0 of 20) of the lung, or large-cell lung cancer (0 of 2). It reacted neither with other malignancies, including colorectal cancer, gastric cancer, and malignant lymphoma, nor with such normal tissues as trachea, lung, liver, pancreas, colon, kidney, spleen, skin, striated muscle, bone marrow, or peripheral blood cells. Interestingly, the antibody cross-reacted with central nervous tissues. The antigenic determinant on small-cell lung cancer and that on human brain were both heat labile and trypsin sensitive, but resisted treatment with neuraminidase, suggesting that they represent similar peptides. TFS-4 may be of clinical use in the diagnosis of small-cell lung cancer, while the antigen may help investigate the nature and origin of small-cell lung cancer.

Antibodies, Monoclonal↗
PubMed1987

Potentiation of cytotoxicity of 1-beta-D-arabinofuranosylcytosine for K562 human leukemic cells by cadeguomycin.

The treatment of K562 human myeloblastic leukemia cells and YAC-1 murine lymphoma cells with cadeguomycin at concentrations over 0.6 microM significantly enhanced the cytotoxicity of 1-beta-D-arabinofuranosylcytosine (ara-C). The degree of potentiation depended upon the antibiotic concentration. The treatment with 75 microM cadeguomycin for 18 h increased cellular uptake of [3H]ara-C into K562 cells and formation of ara-C nucleotides, as well as incorporation into nucleic acids. The level of the diphosphate of ara-C plus the triphosphate of ara-C was approximately 10 times higher in the cadeguomycin-treated cells than in the untreated cells by 30 min of incubation with [3H]ara-C. The extracts of 15 microM cadeguomycin-treated K562 cells showed increased activity of formation of ara-C nucleotides, resulting in 4- to 5-fold higher formation of the di- and triphosphates of ara-C than the control cell extracts. Cadeguomycin did not significantly change the level of ribonucleotide and deoxyribonucleotide pool in K562 cells. The mechanism of potentiation of ara-C by cadeguomycin was discussed.

Anti-Bacterial Agents↗
PubMed1987

Protoplast-mediated gene transfer into human leukemia (K562) cells.

We have examined the usefulness of a protoplast fusion technique as a tool to transfer cloned genes into hematopoietic cells. Protoplasts carrying cloned plasmids, which would express specific markers when successfully transfected into human cells, were prepared and fused with human leukemic cell line K562 cells using polyethylene glycol as a fusogenic factor. As a result, K562 cells fused with protoplasts containing a plasmid pSV2-cat constructed to code for chloramphenicol acetyltransferase (CAT) expressed CAT activity efficiently. K562 cells were also readily transformed to geneticin-(G418) resistant cells following fusion with protoplasts carrying a plasmid pSV2-neo-SV-gpt, which confers the resistance of mammalian cells to G418 and mycophenolic acid. It was also demonstrated that the plasmid genome was stably integrated into the chromosomal DNA of G418-resistant K562 cells. Our results proved that protoplast fusion could be used to study the specific expression and the biologic activities of cloned genes in human hematopoietic cells.

Acetyltransferases↗
PubMed1987

N-terminal amino acid sequence of leukemia derived growth factor (LGF) from human erythroleukemia cell culture.

A human erythroleukemia cell line, K-562 T1, was adapted to a protein-free chemically defined medium; that is, the medium does not contain any proteins such as exogenous hormones, growth factors, serum and serum albumin. The K-562 T1 cells which can proliferate in a protein-free medium are one of the model systems suitably supporting the autocrine hypothesis, which claims that cancer cells produce and respond to their own growth factors. The K-562 T1 cells were cultured in a protein-free medium at large scale and the growth factors were purified from the conditioned medium. It was found that K-562 T1 cells produce at least two growth factors; one is LGF-I (leukemia-derived growth factor-I) which can stimulate the proliferation of a wide range of human leukemia cell lines and the other is LGF-II (leukemia-derived growth factor-II), which can contribute to the growth of fibroblasts. LGF-I was purified using QAE-Sephadex, Bio Gel P-60 and Mono S FPLC. The purified protein was found to be homogenous by SDS-polyacrylamide gel electrophoresis and NH2-terminal sequence analysis. The molecular weight of LGF-I was 20,000 by SDS-polyacrylamide gel electrophoresis. The 30 NH2-terminal residues of LGF-I are the same as that of ubiquitin. Ubiquitin is a protein found in eukaryotic cells with molecular weight of 8,600. In the nucleus ubiquitin is conjugated to histone 2A to form the nuclear protein A24 which may play a role in regulation of chromatin structure, and in the cytoplasm is part of an ATP-dependent non-lysosomal proteolytic pathway. However, its physiological significance has not yet been fully resolved. Ubiquitin purified from bovine thymus did not show cell proliferating activity for any cells tested. The results suggest that LGF-I is a new autocrine growth factor with a molecular weight of 20,000 daltons, containing ubiquitin at the NH2-terminal end.

Amino Acid Sequence↗
PubMed1987

Strength properties of soldered joints for a gold-palladium alloy and a palladium alloy.

Strength of a soldered palladium alloy, PGC (Engelhard Corp.), and a soldered medium gold alloy, PGX (Engelhard Corp.), was examined. The results obtained were as follows: Highest strength was observed with postsoldered specimens of PGC alloy. Microstructural examination of postsoldered specimens revealed nearly pore-free solder joints with PGC and PGX alloys, and fracture appeared at the solder-alloy interface with PGC and PGX alloys. Microstructural examination of presoldered and presoldered/thermocycled specimens revealed that presoldered specimens of PGC and PGX alloys exhibited intrasolder fracture; PGX solder joints had considerably less porosity, which may explain the equivalent bond strengths of all the soldered specimens and the yield point of the controls; PGC solder joints exhibited large quantities of pores, which may explain the lower strength; pores observed in PGC alloy may be the result of the high fusing temperature of the solder; and these results indicate a need to develop a new presolder for PGC. The best result was obtained with postsoldered specimens of the PGC alloy. However, for PGX alloy, either postsolder or presolder techniques can be used.

Dental Alloys↗
PubMed1987

Amplification of N-myc oncogene in stage II and IVS neuroblastomas may be a prognostic indicator.

The amplification of N-myc oncogene is frequently observed in tumors of patients with advanced, poor prognostic stages of neuroblastoma (unfavorable stage group). However, there has been little documentation of the N-myc amplification in tumors of patients with stages II and IVS neuroblastoma (favorable stage group). In this communication, we present data on one patient in stage II and two in stage IVS. In these children, the primary tumors had an amplified N-myc and the clinical course was poor. In addition, from an analysis of the N-myc oncogene of 26 neuroblastomas, genomic amplification of more than three copies was observed in 4 of 11 (36%) in the favorable stage group, and in 9 of 15 (60%) in the unfavorable stage group. Death occurred only in those with an amplified N-myc, in both groups. The smaller copy number of N-myc amplification of stage IVS tumors as compared with those of stages III and IV, appeared to be characteristic. These findings suggest that N-myc amplification may be a reliable prognostic indicator even in the favorable stage group of neuroblastomas, and may be clinically useful as a guide for treating those with a poor prognosis in stages II and IVS.

Adrenal Gland Neoplasms↗