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Biomedical subjects

K Motoyoshi

Publications and source records attributed to K Motoyoshi.

At least 235 records · Page 13Linked to original sources
PubMed1978

Interaction of subunits of polypeptide chain elongation factor I from pig liver. Formation of EF-1alpha.EF-1betagamma and EF-1beta complexes.

In the preceding papers, we showed that one of the two complementar factors of polypeptide chain elongation factor 1 (EF-1) from pig liver, EF-1alpha, functionally corresponds to bacterial EF-Tu (Nagata, S., Iwasaki, K., and Kaziro, Y. (1976) Arch. Biochem. Biophys. 172, 168), while the other, EF-1betagamma, as well as one of its subunits, EF-1beta, corresponds to bacterial EF-Ts (Motoyoshi, K. and Iwasaki, K. (1977) J. Biochem. 82, 703). Therefore, the interaction between EF-1alpha and EF-1 betagamma or EF-1beta was was examined and the following results were obtained. i) EF-1betagamma catalytically promoted the exchange of [14C]GDP bound to EF-1alpha with exogenous [3H]GDP. ii). In the absence of the exogenous guanine nucleotide, EF-1betagamma as well as EF-1beta could displace GDP bound to EF-1alpha to form an EF-1alpha.EF-1betagamma as well as an EF-1alpha.EF-1beta complex. iii) The occurrence of EF-1alpha.EF-1betagamma and EF-1alpha.EF-1beta complexes was demonstrated by gel filtration on Sephadex G-150. These results strongly indicate that the mechanism of the action of EF-1betagamma or EF-1beta in converting EF-1alpha.GDP into EF-1alpha.GTP is analogous to bacterial EF-Ts, and the reaction is accomplished by the following reactions; EF-1alpha.GDP + EF-1betagamma (or EF-1beta) in equilibrium EF-1alpha.EF-1betagamma (or EF-1beta) + GDP; EF-1alpha.EF-1beta (or EF-1beta) + GTP IN EQUILIBRIUM EF-1alpha.GTP + EF-1betagamma (or EF-1beta).

Animals↗
PubMed1978

Purification and some properties of colony-stimulating factor from normal human urine.

A colony-stimulating factor (CSF) that stimulated human and mouse bone marrow cells to proliferate in vitro and form pure granuloid colonies was purified about 4000-fold from normal human urine. Purification procedures included concentration with polyethyleneglycol, ammonium sulfate precipitation, two chromatographic separations on DEAE-cellulose columns, gel filtration, and polyacrylamide gel electrophoresis. The molecular weight of the purified factor was estimated to be about 85,000 daltons by gel filtration, and the specific activity was found to be 10(6) or 6.7 X 10(5) colonies/mg protein using mouse or human bone marrow cells, respectively. A urinary colony-inhibiting factor was separated from the CSF on the first DEAE-cellulose column. This inhibitor suppressed the formation of pure granuloid colonies of human and mouse bone marrow cells when employed in conjunction with the purified urinary CSF.

Chromatography, DEAE-Cellulose↗
PubMed1976

Purification and properties of a new polypeptide chain elongation factor, EF-1beta, from pig liver.

Eukaryotic polypeptide elongation factor 1 (EF-1) from pig liver has been resolved into two complementary factors, EF-1alpha and EF-1beta (Iwasaki, K., Mizumoto, K., Tanka, M., and Kaziro, Y. (1973) J. Biochem. (Tokyo) 74, 849). This paper describes the procedures for purification of EF-1beta and some properties of the purified factor. The purification method includes an aqueous two-phase separation technique, a treatment of the crude factor with sodium cholate and two successive column chromatographies on diethyl-aminoethyl-Sephadex A-50. By this method, EF-1beta was purified about 50-fold starting from the material obtained after two-phase separation followed by ammonium sulfate fractionation with a recovery of 20%. The purified EF-1beta appeared homogeneous, having a molecular weight of about 90,000. It consisted of two unequal subunits of the molecular weights of 55,000 and 30,000. It stimulates polymerization of phenylalanine dependent on poly(U) in the presence of both EF-1alpha and EF-2, as well as the EF-1alpha-dependent binding of phenylalanyl-tRNA to ribosomes in the presence of GTP. However, it had no effect on the stoichiometric binding of phenylalanyl-tRNA to ribosomes dependent on EF-1alpha in the presence of guanyl-5'-yl methylenediphosphonate. These results indicate that the function of EF-1beta is to stimulate the recycling of EF-1alpha.

Animals↗
PubMedDate not supplied

Effects of reactive oxygen species on intracellular calcium in bovine tracheal epithelium: modulation by nitric oxide.

We studied the effects of reactive oxygen species (ROS) on intracellular Ca2+ concentration ([Ca2+]i) and their possible modulation by nitric oxide (NO) in fura-2-loaded cultured bovine tracheal epithelium. Hypoxanthine (HX) and xanthine oxidase (XO), which generate superoxide anion (O2-) and hydrogen peroxide (H2O2), dose dependently increased [Ca2+]i. The increase in [Ca2+]i was reduced in the presence of superoxide dismutase (SOD, 200 U/mL) and catalase (200 U/mL) by 29% and 43%, respectively. The iron chelator o-phenanthroline and the hydroxyl radical (.OH) scavenger dimethylthiourea (DMTU) more potently inhibited the response of [Ca2+]i. H2O2-derived .OH generated by the Fenton reaction caused a marked [Ca2+]i elevation, but exogenous H2O2 did not. Sodium nitroprusside (100 microM), an NO donor, potentiated HX-XO-induced [Ca2+]i rise by 50%, an effect that was abolished in the presence of SOD or DMTU. These results suggest that .OH formed by interaction of O2- and H2O2 in the presence of iron may play a major role in the HX-XO-induced disruption of airway epithelial Ca2+ homeostasis, and that NO potentiates ROS-induced [Ca2+]i response, presumably by reacting with O2- and producing .OH.

Animals↗
PubMedDate not supplied

Macrophage colony-stimulating factor for cancer therapy.

Macrophage colony-stimulating factor (M-CSF) is a homodimeric glycoprotein which stimulates differentiation of progenitor cells to mature monocytes and enhances production of hemopoietic growth factors from mature monocytes such as granulocyte-macrophage CSF, granulocyte CSF and megakaryocyte potentiator, suggesting that M-CSF administration enhances production of monocytes, neutrophils and platelets. Since the commercial availability of M-CSF in 1991, serial M-CSF infusions at a daily dose of 8 million units have been performed in patients with acute myeloid leukemia in complete remission after combination chemotherapy. Although M-CSF infusion reduced the duration of neutropenia in 3 of 5 patients, it reduced the duration of pyrexia over 37 degrees C in all patients, and that over 38 degrees C in 4 of 5 patients. Average durations of pyrexia and parenteral antibiotic injections were significantly shorter in M-CSF than in control courses. Although M-CSF infusion reduced the duration of thrombopenia in 2 of 5 patients, it reduced total platelet units transfused in 4 of 5 patients. The average number of platelet units transfused after combination chemotherapy was significantly lower in M-CSF than in control courses. In mice, M-CSF injection increased the serum concentration of reactive nitrogen intermediates which inhibited the growth of L1210 cells, and increased the survival rate of mice previously injected with them. These results indicate that M-CSF may be a promising agent not for improving patients' quality of life after cancer chemotherapy, but also in cancer immunotherapy.

Adolescent↗
PubMedDate not supplied

Effects of macrophage colony-stimulating factor on the activities of murine monocytes and peritoneal macrophages in vivo.

The ability of peripheral blood monocytes, granulocytes and resident peritoneal macrophages to generate hydrogen peroxide in response to concanavalin A was enhanced by a single intravenous injection of macrophage colony-stimulating factor (M-CSF) of recombinant human type in AKR mice. In response to phorbol myristate acetate, only granulocytes and resident peritoneal macrophages showed the enhanced ability. Phagocytosis by those cells was not stimulated by M-CSF. Surface marker analysis showed an increased expression of F4/80 and Mac1 on monocytes, Mac1 expression on granulocytes and LFA-1 expression on resident peritoneal macrophages. Ia antigen on resident peritoneal macrophages was suppressed by M-CSF. M-CSF can induce monocytes, granulocytes and resident peritoneal macrophages to generate hydrogen peroxide and enhances their maturation in vivo.

Animals↗