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Biomedical subjects

T Okabe

Publications and source records attributed to T Okabe.

At least 379 records · Page 21Linked to original sources
PubMed1986

Lactoquinomycin B, a novel antibiotic.

Streptomyces tanashiensis IM8442T was found to produce lactoquinomycin B, a novel antibiotic, together with lactoquinomycin A. Lactoquinomycin B was purified, and the physico-chemical and biological characteristics were studied. Lactoquinomycin B, C24H27NO9, mp 149-152 degrees C (dec), FD-MS m/z 473 (M+), is a basic substance, showing UV lambda MeOHmax (epsilon) 239 (15,100), 287 (3,450) and 369 nm (5,300), and IR nu CHCl3max 1790 (gamma-lactone), and 1700 and 1650 (quinone) cm-1. The structure of lactoquinomycin B was elucidated by 1H NMR and 13C NMR in comparison with those of lactoquinomycin A, indicating that B is a 4a,10a-epoxide derivative of A. Lactoquinomycin B displayed inhibitory activity against bacteria, particularly Gram-positive organisms, and cytotoxicity against human and murine tumor cell lines. LD50 for mice was ca. 40 mg/kg by iv route.

Animals↗
PubMed1986

Inhibition by sakyomicin A of avian myeloblastosis virus reverse transcriptase and proliferation of AIDS-associated virus (HTLV-III/LAV).

In the course of screening for inhibitors of reverse transcriptase, we have isolated an inhibitor from a strain of Nocardia and identified it as sakyomicin A. The antibiotic blocks avian myeloblastosis virus reverse transcriptase reaction: IC50 was ca. 30 micrograms/ml by the method employed. The drug affects proliferation of HTLV-III/LAV in HTLV-I-carrying MT-4 cells: ca. 60% inhibition was observed at an antibiotic concentration of 1.0 microgram/ml and ca. 20% inhibition at 0.1 microgram/ml, and there was no significant cytotoxicity.

Avian Leukosis Virus↗
PubMed1986

Diagnostic and therapeutic applications of monoclonal antibodies to small cell carcinoma of the lung.

For diagnosis and treatment of small cell lung cancer (SCLC), we have developed two different types of monoclonal antibodies, one of which is useful for specific diagnosis of SCLC. The other has been used for purging tumor cell infiltrates from bone marrow in high-dose chemotherapy followed by autologous bone marrow rescue. The monoclonal antibody, TFS-4, is highly specific for SCLC. It reacts with SCLC but is unreactive with squamous cell carcinoma or adenocarcinoma of the lung. It can distinguish SCLC from non-SCLC in histologic diagnosis at transbronchial biopsy, and in cytological identification of tumor cells in malignant effusions and in infiltrated bone marrow. Radiolabeled TFS-4 specifically accumulated into SCLC tumors and depicted a clear-demarcated tumor image with a gamma scintillation camera. The TFS-4 labeled with 131I inhibited the growth of SCLC tumors transplanted into nude mice. TFS-2 antibody demonstrated "pancarcinoma" reactivity, showing binding to SCLC, non-SCLC, and carcinomas derived from other organs such as the colon, pancreas, and stomach. This antibody failed to react with a variety of normal tissues including lung, bone marrow, spleen, stomach, colon, and pancreas. TFS-2 showed complement-mediated cytolysis of target cells. TFS-2 did not inhibit the growth of hemopoietic progenitors committed to granulocyte-macrophage, or erythroid lineage. In mixed cell populations of tumor cells and bone marrow cells, the antibody effectively killed the tumor cells.

Animals↗
PubMed1986

Recombinant human granulocyte colony-stimulating factor induces granulocytosis in vivo.

Recombinant human granulocyte colony-stimulating factor (G-CSF) was prepared and its granulopoietic effects on mice were examined. When mice were injected intraperitoneally with the G-CSF daily for 14 days, marked granulocytosis occurred in the mice. The number of progenitor cells (CFU-C) was remarkably increased in the spleen. The results suggest that G-CSF plays a central role in granulocyte production in vivo.

Animals↗
PubMed1986

Growth factor(s) produced by a human leukemic cell line growing in a protein-free chemically defined medium.

To examine whether human leukemic cells produce growth factor(s), a protein-free culture line of human erythroleukemic cells (K-562T1) has been established. This unique cell line has been continuously propagated in protein-free Ham's F-10 medium without any supplement for 5 yr. Growth-promoting activity was determined by measuring [3H]thymidine incorporation into DNA in serum-deprived chick embryo fibroblasts. The conditioned medium of K-562T1 contained the growth-promoting activity against chick embryo fibroblasts, mouse 3T3-L1 cells, and K-562 human leukemic cells. This leukemia-derived growth-promoting activity was heat and acid stable and trypsin sensitive. The activity was destroyed by dithiothreitol. Size exclusion chromatography revealed three peaks of activity, with apparent molecular weights of 13,500, 6,300, and 2,400, respectively.

Cell Line↗
PubMed1986

[Results and prevention of complications in bronchoplastic surgery in lung cancer].

Fifty-eight patients have undergone bronchoplastic surgery for lung cancer and were reviewed in an attempt to evaluate its postoperative survival rate and to establish a certain method to prevent postoperative complications. Five-year survival rates of the patients with the reconstructive surgery were 36.9, 66.6, 7.9 per cent in over-all patients, stage I and II patients, and stage III patients, respectively. These results can compare favorable with the results obtained in patients who underwent standard operation for lung cancer. Seven of 9 patients with sleeve lobectomy and pulmonary artery reconstruction died within 2 years and 7 months postoperatively, and 4 of them showed distant metastasis. This type of operation may be alternative to pneumonectomy only when pneumonectomy would not be tolerated because of low cardiopulmonary reserve. Six of 8 patients died within 3 years after carina reconstruction. In this type of operation 4 cases showed tumor relapse around anastomotic site. Including 4 patients with carina reconstruction, 8 cases revealed postoperative local tumor recurrence despite the tumor free bronchial stump by frozen sections. These results indicate that prophylactic radiation therapy may be necessary to prevent local tumor relapse after the reconstructive surgery for the advanced lung cancer patients.

Adenocarcinoma↗
PubMed1985

[Insulin like action of oxytocin].

The insulin-like activity of oxytocin in stimulating glucose oxidation in rat adipocytes has been demonstrated repeatedly in the last 20 years. Oxytocin binds to a specific cell surface receptor of adipocytes; however, little attention has yet been paid to the effect of oxytocin on glucose oxidation in other tissues. We have initiated studies into the metabolicregulatory activity of oxytocin in insulin sensitive tissues and uterus.

Adipose Tissue↗
PubMed1985

1 alpha,25-Dihydroxyvitamin D3 (calcitriol) stimulates proliferation of human circulating monocytes in vitro.

Previous studies demonstrated that human circulating monocytes can proliferate in vitro when incubated with lectin-induced factor(s) from lymphocytes [(1985) Biochem. Biophys. Res. Commun., in press]. This study shows that human monocytes were induced to proliferate when incubated with 1 alpha,25-dihydroxyvitamin D3 (calcitriol) at physiological concentrations. The optimal dose was about 10 nM. Proliferative activity was examined both by measuring the [3H]thymidine incorporation and by counting cell nuclei. Among other derivatives of vitamin D3, 1 alpha,24R-dihydroxyvitamin D3 and 1 alpha,24R,25-trihydroxyvitamin D3 stimulated mitotic activity of monocytes. Addition of both calcitriol and lectin-stimulated lymphocyte-conditioned medium to the monocyte culture had an additional effect on the mitotic activity of monocytes.

Calcitriol↗
PubMed1985

Production of erythropoietin-like activity by human renal and hepatic carcinomas in cell culture.

Two types of human cancers, a renal cell carcinoma and a hepatocellular carcinoma, were investigated in vitro; both produced a marked erythrocytosis in each patient. These tumors, when transplanted into athymic nude mice, produced a remarkable erythrocytosis in the host mice. To analyze this phenomenon, the primary cultures from these xenotransplanted tumors were performed. To obtain pure tumor cell cultures, cells derived from host nude mice were eliminated by the treatment with the antiserum raised against nude mouse cells. Epithelial cells derived from each tumor attached and grew in the cultures. The conditioned media from both tumor cells revealed high erythropoietic stimulatory activities. We have characterized these erythropoietin-like activities by size-exclusion high-performance liquid chromatography. Three peaks of erythropoietin-like activities were noted after bovine serum albumin region. The molecular weights were estimated at about 55,000, 40,000, and 33,000, respectively. The results suggested that the human renal cell and hepatocellular carcinomas produced erythropoietin-like activities in vitro in culture and that erythrocytosis found in patients with cancer and in nude mice transplanted with the tumors was attributable to production of the erythropoietin-like activities by the tumor cells themselves.

Aged↗
PubMed1985

Human myeloid leukemia cells metabolize 25-hydroxyvitamin D3 in vitro.

Human promyelocytic leukemia cells (HL-60) converted 25-hydroxyvitamin D3 to two more polar metabolites during in vitro incubations. A two-step high pressure liquid chromatography system revealed two unique elution positions of those leukemic cell-derived metabolites that exactly co-migrated with the elution positions of 5(Z)-19-nor-10-oxo-25-hydroxyvitamin D3 and 5(E)-19-nor-10-oxo-25-hydroxyvitamin D3, respectively. These unique metabolites did not bind specifically to a protein receptor for 1,25-dihydroxyvitamin D3.

Animals↗
PubMed1985

Activation of the c-K-ras oncogene in a human pancreas carcinoma.

The human pancreas carcinoma cell line T3M-4 contains activated c-Kirsten (K)-ras oncogene detectable by the DNA-mediated gene transfer technique using NIH/3T3 cells. DNA fragments containing coding lesions have been cloned, and nucleotide sequence analysis suggests that the T3M-4 oncogene has been activated by a single nucleotide transition from A to C in the second exon, which results in the substitution of histidine for glutamine in coden 61 of the predicted amino acid sequence. The quantity analysis of c-K-ras oncogene in the DNA and RNA of T3M-4 cells revealed that the c-K-ras gene was amplified and overexpressed in T3M-4 cells. These findings indicate that the T3M-4 c-K-ras oncogene is activated by different mutational events.

Amino Acid Sequence↗
PubMed1985

Induction of proliferation of human circulating monocytes in vitro by lectin-induced factor(s) from lymphocytes.

Human peripheral blood monocytes, which have been considered to be non-dividing cells, were induced to proliferate in vitro by soluble mediator(s) from lectin-activated human lymphocytes. The lectin-induced factor from lymphocytes increased both the number of nuclei of cultured monocytes and [3H]-thymidine incorporation into the monocytes. The molecular weights of the soluble factor(s) that promote growth of monocytes were in the range of 20,000-70,000 daltons with two peaks.

Adult↗
PubMed1985

A platelet factor that stimulates the proliferation of vascular endothelial cells.

The effects of platelet factors on the growth of cultured porcine aortic endothelial cells were studied. Human platelet lysate stimulated the incorporation of [3H] thymidine into DNA. Gel chromatography on Sephadex G-75 revealed at least two peaks of activity on endothelial cells, the major peak being at an apparent molecular weight of 20,000. This activity was heat-labile and trypsin-sensitive, and did not stimulate the growth of fibro-blasts.

Animals↗
PubMed1985

Cytostasis of tumor cell lines by promyelocytic leukemia cell line HL60 differentiated to granulocyte lineage.

The human promyelocytic leukemia cell line HL60, when cultured in medium containing dimethyl sulfoxide (DMSO) or granulocyte colony-stimulating factor (G-CSF), stopped dividing and differentiated into cells with granulocyte characteristics. We found that differentiated HL60 cells have no detectable cytolytic activity against cultured human bladder cell line (T24 cell), as measured by release of (3H) thymidine, or against K562 cells, as measured by release of chromium-51. Differentiated HL60 cells inhibited incorporation of (3H) thymidine into the DNA of adherent T24 cells. Decreased incorporation was not caused by detachment of the target T24 cells from the culture wells. The degree of cytostasis was dependent on the E/T ratio, with a 70%-80% inhibition usually reached at the E/T ratio of 200:1. A wide variety of target cells was also shown to be sensitive to differentiated HL60 cell-mediated cytostasis.

Cell Differentiation↗