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Biomedical subjects

Y Nosoh

Publications and source records attributed to Y Nosoh.

At least 37 records · Page 2Linked to original sources
PubMed1986

Effects of oxygen tension on tumor colony formations assessed by human tumor clonogenic assay.

To clarify the effects of oxygen tension on colony formation of fresh human tumor cells, we examined 25 fresh human tumor samples (sixteen gastric cancers, three colon cancers, three breast cancers, one esophageal cancer, one leiomyosarcoma and one malignant lymphoma), using the human tumor clonogenic assay (HTCA) technique. Three different oxygen tensions (2 per cent, 5 per cent, 20 per cent) were tested. At 5 per cent O2, which is considered to be physiological oxygen tension, 19 out of 26 tumors (13/16 in gastric cancer, 2/3 in colon cancer, 1/3 in breast cancer, 1/1 in esophageal cancer, and 1/1 in leiomyosarcoma) showed significant increases of plating efficiencies as compared to those at 20 per cent O2. On the other hand, decreases in plating efficiencies were observed at 2 per cent O2 in seven out of 12 tumors as compared to 20 per cent O2 and eight out of 12 tumors, as compared to 5 per cent O2.

Cell Division↗
PubMed1986

[In vitro phase II-III study by clonogenic assay: the combined effects of mitomycin C with alpha-interferon].

Using the human tumor clonogenic assay technique, the combined effects of mitomycin C (MMC) with alpha-interferon (HLBI) were surveyed in comparison with 33 fresh human tumor specimens. Tumors in this study were 16 gastric cancers, five breast cancers, four liposarcomas, three colon cancers, two gall bladder cancers, two esophageal cancers, and one hepatoma. When the survival fraction observed in drug combination was smaller than the multiplication of each survival fraction observed in each drug alone, the combined effects were considered to be synergistic. Twenty-two of 33 tumors (gastric cancer 11/16, breast cancer 5/5, liposarcoma 2/4, colon cancer 1/3, gall bladder cancer 2/2, esophageal cancer 1/2, and hepatoma 0/1) formed adequate colony numbers for the evaluation of combined drug effects. Synergistic effects were observed in seven tumors (three gastric cancers, one breast cancer, one gall bladder cancer, one liposarcoma and one esophageal cancer), although three tumors (one gastric cancer, one gall bladder cancer, and one colon cancer) exhibited antagonistic effects.

Cell Division↗
PubMed1986

[Clinical studies on a rapid screening assay for anticancer agents with nude mice and isotopic evaluation].

A rapid method using nude mice has been established as an in vivo model for assessing the chemosensitivity of individual human tumors, in which the final evaluation is made with 3H-thymidine (3H-TdR) incorporation into the treated tumor. In 234 of 289 cancers, the chemosensitivity of anticancer agents was evaluated by this method. This assay proved to be feasible in a sufficiently high percentage of human primary tumors (81.0%). The rate of positive sensitivity against all tumors was 23.8% for MMC, 12.3% for 5-FU, 29.1% for CPM and 23.5% for ADM, respectively. The sensitivity of anticancer agents varied according to the type of cancer. Correlation between the sensitivity test and the end results after chemotherapy in cases of inoperable gastrointestinal cancers was investigated, prospectively. Out of 19 cases, the 50% survival time of 11 patients treated with sensitive agents was longer than that of 8 patients treated with insensitive agents. From a prospective-correlative study carried out on 25 patients, this assay appeared to be correlated with clinical response (overall agreement, 76.0%) with specific agreements of sensitivity and resistance of 37.5% and 94.1%, respectively. From these results, it seems reasonable to conclude that this sensitivity test using a human/nude mouse system is a useful screening assay for revealing appropriate agents for the treatment of patients with cancer.

Animals↗
PubMed1985

Loss of liposome binding of NADH dehydrogenase from alkalophilic Bacillus on subtilisin digestion.

Alkalophile NADH dehydrogenase consisting of two 65-kDa subunits was changed by subtilisin into an enzyme species consisting of two 38-kDa subunits. The amino acid composition and enzyme activity per molecule of the subtilisin-treated enzyme were almost the same as those of the native enzyme, respectively. On mixing with phospholipid liposome, the conformation of the native enzyme was changed, as suggested by the changes in the type of Arrhenius plot and of CD spectrum and enzyme activity. These conformational properties of the subtilisin-treated enzyme, on the other hand, were not affected by liposome. Gel filtration of the subtilisin-treated enzyme mixed with the liposome showed no binding of the protein to liposome.

Amino Acids↗
PubMed1985

In vitro chemosensitivity tests on human tumor xenografts by clonogenic assay: the combined use of mitomycin C with alpha-interferon or gamma-interferon.

Using the human tumor clonogenic assay technique, the effects of Mitomycin C plus either alpha-interferon or gamma-interferon were studied against five human tumor xenografts serially transplanted into nude mice (three gastric and two colon cancers). When the survival fraction found with the drug combination was smaller than the multiplication of survival fractions with either drug alone, the combined effect was defined as synergism. Similarly, antagonistic effect was defined when the survival fraction of drug combination was larger than the larger one observed in either interferon or Mitomycin C alone. Four out of five human tumor xenografts (three gastric and one colon cancers) showed synergistic effects in combination of alpha-interferon with Mitomycin C. Though two gastric cancer xenografts exhibited synergistic effects in combination of gamma-interferon with Mitomycin C, antagonistic effects, which was not found in combination of alpha-interferon with Mitomycin C, were observed in one gastric cancer and one colon cancer xenografts.

Adenocarcinoma↗
PubMed1985

Partial purification and characterization of type I DNA topoisomerase from Bacillus stearothermophilus.

Type I DNA topoisomerase was partially purified from Bacillus stearothermophilus by ammonium sulfate precipitation and column chromatographies on phosphocellulose, DEAE-cellulose and heparin-agarose. On heparin-agarose chromatography, topoisomerase I activity was separated into three fractions (designated Fractions A, B, and C). Each fraction was further subjected to gel filtration on Sephacryl S-200. From electrophoretic analysis on polyacrylamide gel, Fraction A was found to contain two enzyme species having molecular weights of 110,000 and 100,000, and Fraction B one enzyme species with a molecular weight of 80,000. The molecular weight of the enzyme in Fraction C was estimated to be around 150,000 by gel filtration. The enzymes in Fractions A and B exhibited little activity in the presence of Mg2+, while the activity was increased remarkably by NaCl with Mg2+. No activity was observed in the presence of NaCl alone. The enzyme in Fraction C required only Mg2+ for full activity. With Fraction A, the topoisomerase I-induced cleavage sites on tetracycline-resistant plasmid pNS1 (2.55 megadaltons) were mapped. Fraction A cleaved the DNA at ten specific sites. These sites were compared to those of the Haemophilus gallinarum enzyme, which have already been mapped (Shishido et al. (1983) Biochem. Biophys. Acta 740, 108). The results showed that there is a remarkably coincidence between the cleavage sites induced by the B. stearothermophilus and H. gallinarum enzymes.

Binding Sites↗
PubMed1985

[Assessment of the combined effects of mitomycin C with alpha-interferon or gamma-interferon by the clonogenic assay technique].

The combined effects of Mitomycin C (MMC) with alpha-interferon (HLBI) or gamma-interferon (TRP-2), which have become attractive drugs for use as Biological Response Modifiers, were investigated using the human tumor clonogenic assay technique. Tumors in this study were five human tumor xenografts serially transplanted into nude mice (three gastric cancer, two colon cancer). When the survival fraction occurring with the combination was smaller than that obtained by multiplication of the survival fractions occurring with either drug alone, the combined effect was considered to be synergism. Four out of five xenografts (three gastric cancer, one colon cancer) showed synergistic effects for the combination of MMC with alpha-interferon. Although two gastric cancer xenografts showed synergism for the combination of MMC with gamma-interferon, antagonistic effects were observed in one gastric cancer and one colon cancer xenograft.

Animals↗
PubMed1985

[Comparison of human tumor clonogenic and nude mouse-isotope assays in anticancer-agent sensitivity tests].

Comparative studies between the in vitro human tumor clonogenic assay (HTCA) and our original in vivo method (NM-IA) in which the final evaluation was made with 3H-TdR incorporation of tumor cells transplanted into nude mice were simultaneously performed on 44 fresh human solid tumors (22 gastric cancers, 6 breast cancers, 4 gall bladder cancers, 4 liposarcomas and 8 other tumors). Mitomycin C (MMC), 5-fluorouracil (5-FU), adriamycin (ADM) and cyclophosphamide (CPM) were tested. The evaluable rate was 73% (32/44) in HTCA and 89% (38/44) in NM-IA. Although correlation between the results of HTCA and those of MN-IA was obtained for MMC and ADM, no correlation was observed for 5-FU and CPM.

Animals↗
PubMed1984

Enhancement of S1 nuclease-susceptibility of negatively superhelical DNA by netropsin.

It was evidenced that the antibiotic netropsin enhances the single-strand-specific nuclease S1-susceptibility of negatively superhelical DNA. In contrast, an intercalating drug inhibited S1 action on the superhelical DNA. Negatively superhelical DNA is known to possess several (or a number of) unbasepaired sites sensitive to S1 cleavage. S1 cleaves generally the DNA once at these sites to result in production of the full-length linear form. However netropsin-bound DNA had a tendency to be cleaved by S1 simultaneously at plural sites producing several species of linear DNAs smaller than full-length size.

DNA, Viral↗
PubMed1984

Cloning of beta-isopropylmalate dehydrogenase gene from Bacillus coagulans in Escherichia coli and purification and properties of the enzyme.

The beta-isopropylmalate dehydrogenase (2-hydroxy-4-methyl-3-carboxyvalerate: NAD+ oxidoreductase, EC 1.1.1.85) gene from Baccilus coagulans was cloned and expressed in Escherichia coli C600, using pBR322 as a vector plasmid. The B. coagulans enzyme was purified to a homogeneous state from the E. coli carrying a pBR322 - the B. coaglulans enzyme gene hybrid plasmid. The enzyme consists of two subunits of equal molecular weight (4.4 X 10(4) ). The enzyme activity was stimulated by 0.5 mM Mn2+, Mg2+ and Co2+. The enzyme was strongly inhibited by 0.2 mM p-chloromercuribenzoate and the inhibition was completely recovered by 1 mM dithiothreitol. The B. coagulans enzyme was thermostabilized by 1.5 M NaCl. The B. coagulans enzyme is a composite of alpha-helix, beta-sheet and remainder. The secondary structure of the enzyme was appreciably altered by 0.5 mM MgCl2 and 1.5 M NaCl.

3-Isopropylmalate Dehydrogenase↗
PubMed1984

[Sensitivity test of anticancer agents using human tumor xenografts in nude mice with special reference on correlation between clinical effects and chemotherapy].

In order to improve the response rate of chemotherapy, we have investigated to the method for rapid and accurate prediction of the most appropriate anticancer agents. Thus, a rapid method using nude mice has been established as in vivo model for assessing chemosensitivity of individual human tumors, in which the final evaluation was made with 3H-thymidine incorporation and histological changes of tumor cells treated. Correlation between the sensitivity of anticancer agents and retrospective results of gastrectomy in stage IV gastric cancer was investigated. Our sensitivity test indicated a good correlation with clinical therapeutic and immunological effects. From these results, it seems reasonable to conclude that the sensitivity test using human tumor/nude mouse system may be useful for selection of appropriate agents to treat patients with cancer.

Animals↗
PubMed1984

[Increased cytotoxic effects of various anticancer drugs by alpha-interferon (HLBI) on human tumor xenografts in nude mice].

Since interferon (IFN) has a mechanism of action very different from chemotherapeutic agents, it is possible that a combination of two may be of therapeutic value. The authors studied increased cytotoxic effects of anticancer drugs by IFN on human tumors xenografts in nude mice. Tumor used in this study were "SH-10", "S-7379" (gastric cancer) and "O-7294" (malignant melanoma), serially transplanted subcutaneously. IFN was injected, 5 X 10(5) mu/mouse, every day for 2 weeks and a single drug was administered 3 times every fourth day. Cytotoxic effect was determined by tumor size on day 16 after treatment. Of the 7 drugs, MMC and ADM were most effective. Other drugs showed a slight inhibition of tumor growth by combination therapy with drugs and IFN.

Adenocarcinoma↗
PubMed1983

Hydrogen-deuterium exchange studies on guanidinated pig heart lactate dehydrogenase.

Pig heart lactate dehydrogenase becomes more thermostable on increasing the degree of guanidination (conversion of lysine to homoarginine) (Minotani, N., Sekiguchi, T., Bautista, J.G. and Nosoh, Y. (1979) Biochim. Biophys. Acta 581, 334-341). The conformational change of the protein on guanidination was then examined by hydrogen-deuterium (H-2H) exchange reactions. It ws found that (i) the fluctuation degrees of peptides and tyrosine and tryptophan residues in the protein decrease in that order, (ii) two H-2H exchangeable tryptophan residues per subunit are freely accessible to solvent and the fluctuation degrees of the residues does not change on guanidination, (iii) the H-2H exchange detectable tyrosine residues are not freely accessible to solvent and become less fluctuating when 15 lysine residues per subunit are guanidinated, and (iv) the peptides become much less fluctuating on increasing the degree of guanidination. The specific activity of the enzyme decreased on guanidination. The increased thermostability of the protein on guanidination may be related to the decrease in flexibility of the molecular structure by sacrificing the enzyme activity.

Animals↗
PubMed1983

DNA from alkalophilic Bacillus can transform B. subtilis to alkalophily.

On incubation of B. subtilis RM125(arg 15 leuA8 rM- mM-) with DNA from alkalophilic Bacillus, the transformants (Arg+Leu- or Leu-Arg+) appeared at pH 10. The transformants were able to grow even at pH 7. Alkalophilic Bacillus was resistant to bacteriophages ø105D1C2.1012 grown on B. subtilis 1012(r-mM+) and ø105D1C2.ISMR4 grown on B. subtilis ISMR4(rM+rR+mM+mR+), but the recipient B. subtilis and the transformant(Arg+Leu-) were susceptible to both of the bacteriophages. The results indicate that the transformant is a B. subtilis derivative and that alkalophilicity of alkalophilic Bacillus was transferred to B. subtilis.

Alkalies↗
PubMed1982

Effect of guanidination on subunit interactions in hybrid isozymes from pig lactate dehydrogenase.

The thermostability of the isozymes from pig heart (H) and muscle (M) lactate dehydrogenase (L-lactate:NAD+ oxidoreductase, EC 1.1.1.27) decreased in the order of H4 greater than M4 greater than H3M greater than HM3 greater than H2M2, while the thermostability of the isozymes from guanidinated H4 and M4 increased as guanidinated H monomer was substituted by M monomer. The increased thermostability of H4 increased as guanidinated H monomer was substituted by M monomer. The increased thermostability of H4 on guanidination of five lysine residues per subunit was due to the decrease in the standard activation entropy, and no change in the standard activation enthalpy was observed. The more increased thermostability of H4 on further guanidination of lysine residues from 5 to 15 per subunit was due to the increase of the standard activation enthalpy which overcame the decrease in thermostability due to the increase of the standard activation entropy. The results indicate two different mechanisms of stabilization depending on the degree of guanidination. The increase of thermostability, as measured by the change of the standard activation free energy for thermal inactivation of H2M2, was almost the same as that of H4 on guanidination of five lysine residues in an H monomer. This result and the order of thermostability of the isozymes from unmodified and guanidinated H4 and M4 suggest that the increase of thermostability of hybrid isozymes on guanidination of H monomer is due to the change of the heterologous subunit interactions.

Animals↗
PubMed1982

Effect of ATP on glucose-6-phosphate isomerase from Bacillus caldotenax.

Glucose-6-phosphate isomerase (D-glucose-6-phosphate ketol-isomerase, EC 5.3.1.9) from Bacillus caldotenax exhibits negative cooperativity in enzyme activity. Fructose 1-phosphate, fructose, 1,6-bisphosphate, phosphoenolpyruvate, 6-phosphogluconate, 3-phosphoglycerate, ATP and Pi competitively inhibit the enzyme and abolish negative cooperativity in enzyme activity, while glucose 1-phosphate, dihydroxyacetone phosphate, glyceraldehyde 3-phosphate, ADP and AMP do not inhibit the enzyme. Among the inhibitors of which intracellular concentrations can be measured, only ATP inhibits the enzyme and abolishes negative cooperativity in enzyme activity at intracellular concentration. Such ATP inhibition is observed at 65 degrees C, but not at 30 degrees C, and the inhibition becomes less effective as the temperature decreases.

Adenosine Triphosphate↗