Search PubMed⌕ Search

Biomedical subjects

M Oguro

Publications and source records attributed to M Oguro.

At least 91 records · Page 5Linked to original sources
PubMed1983

Reconstitution of endogenous DNA synthesis in isolated nuclei and template activity of chromatin with respect to mode of inhibition by aphidicolin.

We succeeded in reconstituting the endogenous nuclear DNA synthesis of the sea urchin. Endogenous DNA synthesis of isolated nuclei was reconstituted by mixing the salt-treated nuclei (chromatin exhibiting essentially no endogenous DNA synthesis) and the salt extract containing DNA polymerase-alpha. DNA synthesis in this reconstitution system showed a level of activity and a mode of inhibition by aphidicolin similar to those of the original isolated nuclei (noncompetitive with respect to dCTP). On the other hand, the inhibitory mode was competitive with respect to dCTP in DNA synthesis in the reconstituted system obtained from the chromatin and purified DNA polymerase-alpha, indicating that some other factor(s) in addition to DNA polymerase-alpha is necessary for the reconstitution with reference to the inhibitory mode of aphidicolin. We also studied the template activity of the chromatin. When chromatin was used as a template, inhibition by aphidicolin of DNA polymerase-alpha was noncompetitive and uncompetitive with respect to the template at high and low concentrations, respectively. Treatment of chromatin with 5 M urea gave urea-treated chromatin (nonhistone protein-deprived chromatin) and the extract (mainly nonhistone protein fraction). Inhibition by aphidicolin of DNA polymerase-alpha was uncompetitive with respect to the urea-treated chromatin. However, when chromatin reconstituted from the urea-treated chromatin and the extract was used as a template, the inhibitory mode by aphidicolin was similar to that with original chromatin, indicating that the nonhistone protein fraction contained factor(s) which modified the inhibitory mode of aphidicolin. Thus, the inhibitory mode of aphidicolin is a useful parameter for monitoring the resolution and reconstitution of endogenous DNA synthesis of isolated nuclei.

Animals↗
PubMed1983

[Phase II study with methyl-6[[[2-chloroethyl) nitrosoamino] carbonyl] amino]-6-deoxy-alpha-D-glucopyranoside (MCNU) in hematological malignancies].

A total of 117 cases with hematological malignancies were treated with MCNU at doses of 70-100 mg/m2. Following are the results obtained. 1. MCNU showed a marked depression of cells in the cases with CML, polycythemia vera and thrombocythemia. The low level of cells was maintained for 2 to 7 months. 2. A good response was observed in several cases with blastic crises of CML. 3. No response was observed in two cases with acute leukemia. 4. Although a fair response was observed in several cases with malignant lymphoma or multiple myeloma, moderate bone marrow suppression was observed in a majority of the cases.

Adult↗
PubMed1982

The inhibitory mode of aphidicolin on DNA synthesis in NaCl-treated HeLa cell nuclei.

Isolated HeLa cell nuclei were treated with NaCl at various concentrations and inhibition by aphidicolin of DNA synthesis in the treated nuclei was studied. The inhibition was either noncompetitive or of the mixed type with respect to each dNTP when the nuclei were treated with NaCl at concentrations lower than 0.08 M. However, aphidicolin was a competitive inhibitor with respect to dCTP and a non-competitive or mixed type inhibitor with respect to the other 3 dNTPs when they were treated with NaCl at concentrations higher than 0.1 M. These results suggest the presence of nuclear factor(s) responsible for the changes in the inhibitory mode of aphidicolin on endogenous nuclear DNA synthesis.

Aphidicolin↗
PubMed1982

Inhibition of eukaryotic DNA polymerase-alpha by polydeoxynucleotides.

Effects of polydeoxynucleotides on the activity of DNA polymerase-alpha from sea urchin embryos were studied. Poly(dG), poly(dC) and poly(dC)-oligo(dG)12-18 inhibited DNA polymerase-alpha activity in the activated DNA-directed reaction but poly(dA), oligo(dT)12-18, and poly(dA)-oligo(dT)12-18 did not inhibit the activity. The inhibitory mode of poly(dC)-oligo(dG)12-18 or poly(dC) was competitive with activated DNA and that of poly(dG) was noncompetitive with activated DNA. Using poly(dA)-oligo(dT)12-18 as a template-primer, the inhibition with either poly(dG) or poly(dC)-oligo(dG)12-18 was competitive with the template-primer. These kinetic results indicate that each of the template-primers tested binds to an identical site on DNA polymerase-alpha. Similar results were obtained with DNA polymerase-alpha from HeLa cells.

Animals↗
PubMed1982

[Treatment of malignant lymphoma with single administration of BH-AC (N4-behenoyl-1-beta-D-arabinofuranosylcytosine].

Twenty-two patients with malignant lymphoma and its allied diseases, consisting of 6 with Hodgkin's disease, 10 with non-Hodgkin's's diffuse lymphoma, 4 with leukemic lymphosarcoma and 2 with immunoblastic lymphadenopathy, were entered into this study. The treatment schedule was intravenous drip infusion of the drug, at a dose of 2.3 to 5.4 mg/kg (150 mg to 300 mg/day), for consecutive 4 to 14 days. The total dose given ranged from 1050 to 2500 mg. Four of the 6 patients with Hodgkin's disease and 5 of the 10 patients with non-Hodgkin's diffuse lymphoma showed a good response. The response started from 3 to 7 days after beginning of BH-AC administration and remission induced by BH-AC persisted for 4 weeks. Clinical toxicities such as anorexia, nausea and vomiting were very mild, but hematological toxicities such as thrombocytopenia, leukopenia, and anemia were frequent especially in the patients who were totally given more than 2100 mg. This study suggested that malignant lymphoma responded definitely to single administration of BH-AC and that BH-AC might be a new useful drug for multi-combined chemotherapy of malignant lymphoma.

Adult↗
PubMed1982

[Pas reaction].

Explore the source record for details and available documents.

Blood Cells↗
PubMed1982

[Phase I study of a new antitumor antibiotic, neothramycin].

Phase I study of a new antitumor antibiotic, neothramycin which belongs to anthramycins was performed by a cooperative study group involving 15 major institutions. A total of 63 cases including 42 various solid tumors and 21 hematologic tumors refractory to standard treatments underwent the study during June 1979 to June 1981. Doses of single injection were escalated from an initial dose of 2 mg/m2 estimated by one twentieth of LD10 in mice up to 60 mg/m2. The most frequent and severest toxicity was nausea and vomiting seen in about the half of patients being administered dosages ranged from 24 mg/m2 to 40 mg/m2, and 3 out of 4 patients received dosages exceeding 50 mg/m2 required clinical managements; moreover, 1 out of 2 patients administered 60 mg/m2 was ranked as grade 4 of the criterion of toxicities in WHO handbook. Other clinical toxicities such as skin rash, hepatotoxicity or nephrotoxicity observed in the minority of the patients were reversible. Furthermore, hematologic toxicity was extremely mild and appeared not to be dose dependent. One patient with chronic myelogeneous leukemia had a hematological improvement and the other with esophageal cancer had a partial response. The result indicates that a dose limiting factor of neothramycin is nausea and vomiting, and a maximum tolerated dose of a single injection is 60 mg/m2. A dose schedule of 30-40 mg/m2 appears to be an optimal dose for Phase II study.

Animals↗
PubMed1981

Phase I--II study of N4-behenoyl-1-beta-D-arabinofuranosylcytosine.

A phase I-II study of N4-behenoyl-1-beta-D-arabinofuranosyl-cytosine (BH-AC) was conducted by a cooperative study group. In phase I study, a total of 126 patients, 64 of whom had metastatic solid tumors and 62 of whom had leukemia, were administered BH-AC in a single IV dose at day 1 only or in daily IV doses for 3 to 21 days, with dose ranges of 1.5--10.0 mg/kg. Side effects included nausea and vomiting, which were significantly less in incidence and severity than those observed with ara-C. Myelosuppressive toxicity became severe with doses 3.6--5.0 mg/kg per day x 10 days. In phase II study, a total of 37 adult patients with acute leukemia were entered in the study. Responses were noted, with an overall rate of 35% complete remission. Of th 26 patients with AML, there were 13 CR. The recommended schedule of treatment for BH-AC, based on our data, is daily infusion of 4--5 mg/kg over 3 h for approximately 3 weeks. The results with BH-AC in patients with acute leukemia are superior to those which have been reported for ara-C.

Adolescent↗
PubMed1979

The mode of inhibitory action by pyridoxal 5-phosphate on DNA polymerase-alpha and -beta.

The kinetics of the inhibition of DNA polymerases-alpha and -beta from sea urchin embryos by pyridoxal 5-phosphate were studied. The inhibition of DNA polymerase-alpha activity by pyridoxal 5-phosphate was competitive with activated DNA but noncompetitive with each deoxynucleoside triphosphate. With poly(dC)-oligo(dG)12-18 as a template-primer, however, the inhibition of DNA polymerase-alpha was competitive with dGTP but noncompetitive with the template-primer. These results suggest that DNA polymerase-alpha interacts with activated DNA and poly(dC)-oligo(dG)12-18 in different ways. The inhibition of DNA polymerase-beta by pyridoxal 5-phosphate was competitive with deoxynucleoside triphosphate using activated DNA as a template-primer and noncompetitive with activated DNA. Using poly(rA)-oligo(dT)12-18 as a template-primer, DNA polymerase-beta activity yielded sigmoid curves against both dTTP and the template-primer concentrations and was inhibited by pyridoxal 5-phosphate noncompetitively with respect to both dTTP and the template-primer. These results indicate that the inhibitory mode of DNA polymerase-alpha by pyridoxal 5-phosphate is different from that of DNA polymerase-beta.

Animals↗
PubMed1979

Inhibition by aphidicolin of cell cycle progression and DNA replication in sea urchin embryos.

We have recently found that aphidicolin, a tetracyclic diterpene-tetraol produced by several fungi, blocks DNA synthesis of sea urchin embryos by interfering with the activity of DNA polyermase alpha. These cells fail to proliferate in the presence of aphidicolin. In continuation of these studies, we determined the drug-sensitive stage in the first cell cycle of the sea urchin Clypeaster japonicus embryo. In continuous exposure to aphidicolin (2 micrograms/ml) from five minutes after fertilization, mitotic division of the embryo was completely suppressed. Embryos were exposed to the drug at progressively later intervals and their capability for cytokinesis was examined. Evidence was thereby obtained that aphidicolin acts at the S-period to inhibit DNA synthesis resulting in developmental arrest of the embryo.

Animals↗
PubMed1979

The mode of inhibitory action by aphidicolin on eukaryotic DNA polymerase alpha.

The mode of action by aphidicolin on DNA polymerase alpha from the nuclear fraction of sea-urchin blastulae was studied. The inhibition of DNA polymerase alpha by aphidicolin was uncompetive with activated DNA and competitive with the four deoxynucleoside triphosphates using activated DNA as a template-primer. For truncated (residual or limited) DNA synthesis with only three deoxynucleoside triphosphates, aphidicolin inhibited the residual synthesis more strongly in the absence of dCTP than in the absence of each of the other three deoxynucleoside triphosphates. The inhibition was reversed with excess dCTP but not with the other three deoxynucleoside triphosphates. That is, aphidicolin inhibited DNA polymerase alpha by competing with dCTP with a Ki value of 0.5 microgram/ml and by not competing with the other three deoxynucleoside triphosphates. dTMP incorporation with the activated DNA was more sensitive to aphidicolin than dGMP or dTMP incorporation with poly(dC). (dG)12-18 or poly(dA) . (dT)12-18. Similar results were obtained for DNA polymerase alpha (B form) from mouse myeloma MOPC 104E.

Animals↗