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Biomedical subjects

C Nakayama

Publications and source records attributed to C Nakayama.

At least 19 recordsLinked to original sources
PubMed1991

Purification and characterization of three forms of differently glycosylated recombinant human granulocyte-macrophage colony-stimulating factor.

We have purified recombinant human granulocyte-macrophage colony-stimulating factor (hGM-CSF) produced in human lymphoblastoid Namalwa cells. From the results of tunicamycin treatment and N-glycosidase F digestion, it was demonstrated that Namalwa-derived hGM-CSF was highly glycosylated at two potential N-glycosylation sites and several O-glycosylation sites as previously shown for naturally occurring hGM-CSF. We classified the hGM-CSF molecules into three groups according to the molecular weight corresponding to the degree of N-glycosylation: the molecules with two N-glycosylation sites occupied (designated 2N), the molecules with either site glycosylated (1N), and the molecules lacking N-glycosylation (0N). Despite such varied degrees of N-glycosylation, almost all molecules were O-glycosylated. To investigate the role of carbohydrate moieties of hGM-CSF, we isolated each form of hGM-CSF and examined its biological properties. The 2N-type showed 200-fold less in vitro specific activity compared with unglycosylated Escherichia coli-derived hGM-CSF, although the activity of the 0N-type was equivalent to that of the E. coli-derived material. The 1N-type showed an intermediate level of activity. However, in terms of clearance from blood circulation in the rat, the 2N-type showed a half-life five times longer than that of the 0N-type and E. coli-derived hGM-CSF. From these findings, we concluded that N-linked carbohydrate moieties of hGM-CSF play conflicting physiological roles in the efficacy of the protein in vivo but that O-linked carbohydrate moieties do not have such effects.

Animals↗
PubMed1990

Amplification and high-level expression of a cDNA for human granulocyte-macrophage colony-stimulating factor in human lymphoblastoid Namalwa cells.

We have achieved high-level expression of human granulocyte-macrophage colony-stimulating factor (GM-CSF) in human lymphoblastoid Namalwa cells by introducing and subsequently amplifying an expression vector encoding human GM-CSF and mouse dihydrofolate reductase (DHFR). Transformants expressing elevated levels of both GM-CSF and DHFR were selected by a step-wise increase in the concentration of methotrexate (MTX). Several cell lines resistant in 800 nM MTX have been established that express GM-CSF at a rate of 10-20 micrograms/10(6) cells/day. The amplified genes are integrated and stably maintained in the chromosomes of these cell lines. Analysis of the GM-CSF produced in the amplified Namalwa cells revealed that the molecular-size distribution due to varied degrees of glycosylation was similar to that observed in the naturally-occurring molecules.

Cloning, Molecular↗
PubMed1988

Structure-function relationships in the transposition protein B of bacteriophage Mu.

The B-protein of phage Mu, which is required for high frequency intermolecular transposition in vivo, shows ATPase activity in vitro, binds nonspecifically to DNA, and stimulates intermolecular strand transfer. To elucidate the structural bases for B-protein function, it was subjected to limited proteolysis with two different proteases, trypsin and chymotrypsin. The resulting fragments were mapped by amino acid sequencing. These data show that the B-protein is organized in two domains: an amino-terminal domain of 25 kDa and a carboxyl-terminal domain of 8-kDa. A fragment analogous to the amino-terminal domain, produced by deleting the 3' end of a cloned B gene, proved to be insoluble and had to be renatured after elution from a sodium dodecyl sulfate gel. The renatured protein retains ATP-binding activity and to a lesser extent the DNA-binding activity of the MuB protein, but is unable to hydrolyze ATP or function in transposition. We also show in this study that efficient DNA-strand transfer by the B-protein occurs even in the absence of a detectable ATPase activity or in the presence of adenosine 5'-O-(thio)triphosphate (ATP gamma S).

Adenosine Triphosphate↗
PubMed1988

Benadrostin, new inhibitor of poly(ADP-ribose) synthetase, produced by actinomycetes. I. Taxonomy, production, isolation, physico-chemical properties and biological activities.

Benadrostin, a new inhibitor of poly(ADP-ribose) synthetase was discovered in the fermentation broth of Streptomyces flavovirens MH499-O'F1. It was purified by chromatography followed by solvent extraction and then isolated as colorless prisms. Benadrostin has the molecular formula of C8H5NO4. It was competitive with the substrate, and the inhibition constant (Ki) was 34 microM.

Fermentation↗
PubMed1987

[Bone scintigraphy in bone metastases due to prostatic cancer].

Findings of bone scintigraphy with 99mTc-MDP were compared with bone radiography and biochemical data including total acid phosphatase (T. ACP), prostatic acid phosphatase (P. ACP), and alkaline phosphatase (ALP) in 35 patients with histologically proven prostatic cancer. Bone metastases were diagnosed in 20 of 35 cases (57%) by scintigraphy. The common sites of metastases were the pelvic bones, ribs, lumbar and thoracic vertebrae. In vertebrae, metastases were mainly distributed in the lower level. The most frequent radiographic change due to metastases was the osteoblastic type. On follow-up studies, there was a relatively good agreement in the results of bone scintigraphy and radiography. However, there was a good number of cases showing discrepancy between either scintigraphy or radiography and laboratory data. Bone scintigraphy seems to be the most contributory in monitoring bone metastases from prostatic cancer.

Aged↗
PubMed1987

Structural domains in phage Mu transposase: identification of the site-specific DNA-binding domain.

Limited proteolysis of phage Mu transposase with three proteases of differing specificities produced a common pattern of fragmentation. The fragments were mapped by using a combination of immunoblotting and amino acid sequence analysis. Our results suggest that the transposase molecule is organized principally into three domains: an amino-terminal domain of molecular mass 30 kDa, a core region of approximately 35 kDa, and a carboxyl-terminal domain of approximately 10 kDa. The amino-terminal domain has at least two additional sites that are partially accessible to proteases. Filter binding and nuclease protection studies were done to determine the functions of the isolated domains. Site-specific binding to Mu DNA was localized to the amino-terminal domain. The core domain showed nonspecific DNA-binding activity.

Amino Acid Sequence↗
PubMed1987

Inhibitory effects of 5-alkyl- and 5-alkenyl-1-beta-D-arabinofuranosyluracil 5'-triphosphates on herpes virus-induced DNA polymerases.

Various 5-substituted 1-beta-D-arabinofuranosyluracil 5'-triphosphates (H, methyl, ethyl, n-propyl, n-butyl, (E)-bromovinyl, styryl, and beta-phenylethyl derivatives) were prepared and their inhibitory effects on two different herpes virus-induced DNA polymerases (OMV and HCMV) were studied. These dTTP analogues inhibited the incorporation of [3H]dTMP into DNA in vitro. Among them, analogues having a vinyl group at the 5-position were strongly active against DNA polymerases induced on herpes virus infection. Kinetic analysis showed that the inhibition by the analogues was essentially competitive with respect to the substrate, dTTP. The K1 values (microM) for AraUTP (2.4), AraTTP (1.0), BVAUTP (0.8), and StUAUTP (0.8) were smaller than the Km value (microM) for dTTP (3.4), but those for AraEtUTP, AraPrUTP, and AraBuUTP (5-14) were larger than the Km for dTTP in the case of HCMV-induced DNA polymerase. In contrast to these results, OMV-induced DNA polymerase seemed to be more resistant to these inhibitors than HCMV-induced DNA polymerase. However, the mode of the structure of substituent groups at the 5-position of base moieties is almost the same for the two DNA polymerases, except for in the case of AraUTP itself.

Antiviral Agents↗