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Biomedical subjects

K Shimura

Publications and source records attributed to K Shimura.

At least 127 records · Page 7Linked to original sources
PubMed1985

[Studies on the antitumor activity of traditional Chinese medicines. (1)].

The antitumor activity of Traditional Chinese Medicines (Zhu-Ling-Tang, Xiao-Chai-Hu-Tang, Shi-Quan-Da-Bu-Tang, Bu-Zhong-Yi-Qi-Tang and Ren-Shen-Tang was examined using Ehrlich ascited carcinoma (EAC) in ICR mice. These drugs suppressed the growth of EAC when administered intraperitoneally. In the case of p.o. treatment, Shi-Quan-Da-Bu-Tang, Xiao-Chai-Hu-Tang and Zhu-Ling-Tang also prolonged the survival time of mice bearing EAC.

Animals↗
PubMed1985

[Studies on the antitumor activity of traditional Chinese medicines. (II). The antitumor mechanism of traditional Chinese medicines].

Either i.p. or p.o. administration of Zhu-Ling-Tang, Xiao-Chai-Hu-Tang, Shi-Quan-Da-Bu-Tang and Ren-Shen-Tang enhanced the function of the reticuloendothelial system (RES) in mice. The relative organ weights of thymus, spleen and liver were increased as compared with the control. Furthermore, binding of C3 cleavage product (C3b) to peritoneal macrophages after p.o. administration of Xiao-Chai-Hu-Tang was enhanced as shown by fluorescent antibody technique. In conclusion, it was considered that one of the mechanisms of the antitumor activities of theses drugs was the stimulation of a host-mediated factor such as the phagocytic function of the RES and C3 cleavage producibility.

Animals↗
PubMed1984

High-performance affinity chromatography of plasmin and plasminogen on a hydrophilic vinyl-polymer gel coupled with p-aminobenzamidine.

p-Aminobenzamidine was covalently attached via a spacer moiety to a microparticulate hydrophilic vinyl-polymer gel (Toyopearl HW65S) and this affinity adsorbent was used for the separation of plasmin and plasminogen by high-performance affinity chromatography. Toyopearl HW65S was alkylated with chloroacetylglycylglycine in dimethyl sulphoxide using methylsulphinyl carbanion as a catalyst, then p-aminobenzamidine was coupled to the carboxyl group of glycylglycine to form an acid amide bond. A column packed with the adsorbent retained both plasmin and plasminogen. Plasminogen was eluted with 6-aminohexanoic acid, a haptenic compound for the lysine-binding sites of plasminogen. For the elution of plasmin, the coexistence of 6-aminohexanoic acid and leupeptin (a competitive inhibitor for plasmin) was necessary. The results indicate a two-site interaction of plasmin with the immobilized ligand, i.e., at the lysine-binding sites and the catalytic site. Fluorometric detection of eluted protein and on-line assay of plasmin activity using a fluorogenic substrate, peptidylmethylcoumarylamide, revealed that effective chromatographic separation of the enzyme could be achieved with high sensitivity (10 micrograms) within 1 h.

Amidines↗
PubMed1984

Sequence polymorphisms in the 5'-upstream region of the fibroin H-chain gene in the silkworm, Bombyx mori.

DNA fragments containing the fibroin H-chain gene from two different strains of Bombyx mori, J-139 and Nd (2) were cloned into phage lambda Charon 4A. Comparison of the restriction sites in these cloned DNAs revealed that in addition to the known polymorphism in the region coding for the repetitive amino acid sequence of the fibroin H-chain [Manning and Gage, J. Biol. Chem. 255 (1980) 9451-9457], at least two other types of polymorphism were present, one around the 5' end of the structural gene, and the other in the far upstream region of the gene. Restriction sites around the 5' end of the gene were well conserved between these strains, but some heterogeneity, suggesting the presence of small insertions, deletions or base changes, was noted. In contrast, DNA sequences of the region 2-4 kb upstream from the 5' end of the gene were markedly different between these two strains, indicating that either a deletion or an insertion of a DNA sequence longer than 2 kb had occurred in this region. Comparison with several other strains suggested that the observed changes in the far-upstream region were unique to the Nd(2) strain.

Animals↗
PubMed1984

Reduced level of secretion and absence of subunit combination for the fibroin synthesized by a mutant silkworm, Nd(2).

Fibroin is normally composed of one H chain (350 kd) and one L chain (25 kd) which are connected by disulfide bond(s). However, the small amount of fibroin secreted into the lumen of the posterior silk gland of the Nd(2) (naked pupa) mutant does not contain L chain, although L chain mRNA is present and L chain is synthesized in the posterior silk gland cells of the mutant. In a hybrid silkworm, Nd(2)/Tamanashikasuri, where Tamanashikasuri is a normal producer of fibroin, L chain from the two alleles are distinguishable electrophoretically. It is demonstrated using this system that the L chain from the Nd(2) allele can combine normally with the H chain from Tamanashikasuri and the H-L complex is secreted normally. In another hybrid system, Nd(2)/J-131, where J-131 is a normal producer of fibroin, fibroin derived from the two alleles are distinguishable due to the different electrophoretic mobility of H chain. The fibroin derived from the J-131 allele is composed of H chain and L chain, while the fibroin derived from the Nd(2) allele is devoid of L chain, and its secretion is greatly reduced. We present evidence suggesting that the H chain derived from the Nd(2) allele is structurally abnormal and discuss how the H-L subunit structure is advantageous in the secretion of fibroin.

Alleles↗
PubMed1984

Unwinding of DNA by nonhistone chromosomal protein HMG(1 + 2) from pig thymus as determined with endonuclease.

A high mobility group (HMG) nonhistone protein fraction HMG(1 + 2), composed of HMG1 and HMG2, was prepared from pig thymus chromatin. In order to examine a possibility that the HMG(1 + 2) participates in the unwinding of the DNA double-helix, DNA hydrolysis assay systems with the endonucleases specific for single-stranded DNA were employed. In the presence of HMG(1 + 2), the hydrolysis of double-stranded DNA by N. crassa endonuclease was markedly promoted, while the hydrolysis of single-stranded DNA was hardly enhanced. The reaction kinetic data showed that the stimulation of the hydrolysis of double-stranded DNA in the presence of HMG(1 + 2) was due to the unwinding of the DNA double-helix by the HMG(1 + 2), and not due to stimulation of enzyme activity of the endonuclease by the protein. The unwinding reactions were dependent on the HMG protein concentration at low weight protein to DNA ratios and reached a maximum at the ratio of 0.025. The region unwound in the whole DNA was partial. Similar results were obtained for experiments with nuclease S1. Isolated HMG1 and HMG2 fractions showed DNA unwinding activity of similar extents. The association constant obtained by fluorescence quenching analysis showed that the HMG(1 + 2) has higher affinity to single-stranded DNA than to double-stranded DNA. The susceptibility to the unwinding differed with the DNA source. These results suggest that HMG(1 + 2) at a low weight protein to DNA ratio binds to some limited double-stranded region in DNA and unwinds the DNA partially.

Animals↗
PubMed1984

Mg2+-dependent unwinding of DNA by nonhistone chromosomal protein HMG(1 + 2) from pig thymus as determined by DNA melting temperature analysis.

In the previous studies with endonucleases specific for single-stranded DNA, we have indicated that the nonhistone chromosomal protein HMG(1 + 2) prepared from pig thymus has an activity to unwind DNA partially at low protein-to-DNA weight ratios (Yoshida, M. & Shimura, K. (1984) J. Biochem. 95, 117-124). In the present work, we have pursued the unwinding reaction by HMG(1 + 2) by thermal melting temperature analysis of DNA, and by investigating the effect of Mg2+ on the reaction. The melting temperature of DNA in the presence of HMG(1 + 2) at low protein weight ratios decreased in 2 mM Tris-HCl, pH 7.8, whereas it increased at higher ratios. The depressions of melting temperature by HMG(1 + 2) at low ratios were not observed either in the system of 2 mM Tris-HCl, pH 7.8, containing EDTA or in the system containing samples treated in advance with EDTA. An addition of Mg2+ to the system reproduced the depression of melting temperature at low protein-to-DNA ratios as well as the increase at higher ratios. Analysis by Mg2+-equilibrated gel filtration revealed that HMG(1 + 2) is a Mg2+-binding protein. However, the depression of melting temperature at low protein-to-DNA ratios was not due to removal of Mg2+ from DNA by HMG(1 + 2). From these results, it is concluded that HMG(1 + 2) causes a partial DNA unwinding detectable by thermal melting temperature analysis of DNA, and that Mg2+ is necessary for the unwinding reaction.

Animals↗
PubMed1984

Predominant synthesis of fibroin heavy and light chains on the membrane-bound polysomes prepared from the posterior silk gland of the silkworm, Bombyx mori.

Membrane-bound polysomes were prepared from the posterior silk gland of the silkworm, Bombyx mori, on the fourth to fifth day in the fifth larval instar. The polysomes, when supplemented with a soluble fraction from the posterior silk gland, exhibited the elongation reaction of the growing polypeptide-chains, but the initiation reaction of polypeptide synthesis was not demonstrated in this system. The predominant products synthesized on the membrane-bound polysomes were fibroin heavy chain (H-chain) and light chain (L-chain), while polypeptides of heterogeneous size classes were synthesized on the 105,000 X g-sedimentable polysomes. A substantial fraction of the fibroin L-chain synthesized was bound to the H-chain by disulfide bond. Most of the newly synthesized fibroin H- and L-chains on the membrane-bound polysomes were proved to be present within microsomal membrane vesicles because of their insensitivity to digestion with proteases in the absence of Triton X-100.

Animals↗
PubMed1984

Studies on immunological properties of fibroin heavy and light chains.

Silk fibroin is composed of heavy (H-) and light (L-) chains linked with disulfide bond(s). This paper describes immunological properties of fibroin H- and L-chains. Antiserum against H-chain, L-chain or whole fibroin could be obtained, indicating that each of these polypeptides is antigenic in rabbits. The antiserum against whole fibroin reacted with H- and L-chains. The antiserum against H-chain did not react with L-chain. Similarly, the anti-L-chain serum did not cross-react with H-chain. These results demonstrated that H- and L-chains have different antigenic determinant groups. Sericin-free fibroin samples prepared by boiling the cocoon protein in acid or 1% Na-oleate reacted with both anti-L-chain and anti-H-chain sera, indicating that the subunit structure of fibroin is stable under the drastic conditions of desericinization.

Animals↗
PubMed1984

Unwinding of DNA by nonhistone protein HMG1 and HMG2.

The enzyme kinetic studies with endonucleases specific for single-stranded DNA and the thermal denaturation analyses of DNA showed that a high mobility group (HMG) nonhistone protein fraction HMG (1 + 2), composed of HMG1 and HMG2, has an activity to unwind DNA partially at low protein-to-DNA weight ratio. Isolated HMG1 and HMG2 have the same activity. Divalent cations such as Mg++ or Ca++ were necessary for the unwinding reaction. A peptide containing high glutamic and aspartic (HGA) region, isolated from the tryptic digest of HMG (1 + 2), unwound DNA depending on the presence of Mg++ or Ca++, suggesting that the HMA region in HMG protein is the active site for the DNA unwinding reaction. Poly-L-glutamic acid, employed as a model peptide of the HGA region, showed the activity. Finally, mechanisms of the DNA unwinding reaction by the HMG protein and possible role of the divalent cations are discussed.

Animals↗
PubMed1983

Screening of host-mediated antitumor polysaccharides by crossed immunoelectrophoresis using fresh human serum.

On crossed immunoelectrophoresis, human serum C3 (the third component of complement) converted by antitumor polysaccharides (ATSO [antitumor polysaccharide oral], AB-P [Agaricaus blazei polysaccharide], GU-P [Grifora umbellata polysaccharide], PS-K [polysaccharide Kureha] and zymosan) moved faster than native C3, appearing as the 3rd peak. The ratio of height of the 3rd peak to the alpha 2-macroglobulin (alpha 2-M) peak was linearly proportional to the dose of ATSO. At the dose of 500 micrograms/ml antitumor polysaccharides, the ratios were higher than 0.76, and the ratios for the serum treated with polysaccharide of no antitumor activity (dextran and gum arabic) were less than about 0.52. This ratio readily determined in vivo can be used as a measure for the antitumor activity of polysaccharides.

Animals↗
PubMed1983

Enhancement of antibody-independent phagocytosis by N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7).

A low-molecular weight compound N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7) resulted in strongly enhanced phagocytosis of polystyrene latex beads by peritoneal macrophages of BALB/c mice after intraperitoneal administration. Binding of C3 cleavage product (C3b) to peritoneal macrophages after intraperitoneal injection of W-7 was also enhanced as shown by fluorescent antibody technique. Antibody against W-7 was not detected in the sera of these mice. Therefore, close association of enhanced phagocytosis of polystyrene latex beads with increased binding of C3 cleavage product to macrophages was demonstrated through induction by a low-molecular weight compound in vivo.

Animals↗
PubMed1983

IMP dehydrogenase. I. Studies on regulatory properties of crude tissue extracts based on an improved assay method.

Inhibition of conversion from IMP to uric acid, which interferes with both spectrophotometric and radioisotopic assays of IMP dehydrogenase, by addition of allopurinol (0.1 mM), an inhibitor of xanthine oxidase, to the incubation system made it possible to determine the enzyme activity in crude liver extracts. With this improved assay method, the regulatory properties of the enzyme in crude extracts of liver and Yoshida sarcoma ascites cells were examined. In both tissues IMP dehydrogenase was found in the postmicrosomal supernatant. However, further centrifugation resulted in precipitation of the enzyme, the enzyme from Yoshida sarcoma ascites cells being precipitated more easily than that from rat liver. It was also found that IMP dehydrogenase activity increased during liver regeneration and that this increase was associated with the precipitate from the postmicrosomal fraction. These findings suggest that such a large sedimentable complex including IMP dehydrogenase might be formed in relation to cell growth. Most of the enzyme activity in rat liver and Yoshida sarcoma ascites cells was extracted in the supernatant obtained by centrifugation at 105,000 X g for 4 h after treatment of tissue homogenates with 1 M KCl, 0.75 M (NH4)2SO4, 2 M dimethylsulfoxide, 2 M KSCN, 25% glycerol, or 0.8 M guanidine-HCl. Treatment with 2% deoxycholate, 2% Triton X-100 or 2 M urea gave limited extraction. The enzyme was retained on a phenyl-Sepharose CL-6B or octyl-Sepharose CL-6B column and eluted with 0.8 M guanidine-HCl. These results suggested that the enzyme molecule has not only ionic but also hydrophobic domains, through which it interacts with other molecules of the enzyme itself and/or postmicrosomal cellular components.(ABSTRACT TRUNCATED AT 250 WORDS)

Allopurinol↗
PubMed1983

IMP dehydrogenase. II. Purification and properties of the enzyme from Yoshida sarcoma ascites tumor cells.

The preceding paper showed that IMP dehydrogenase [IMP:NAD+ oxidoreductase, EC 1.2.1.14] tended to form a precipitable complex(es) through ionic and hydrophobic interactions. On the basis of these observations, a method was developed for purification of IMP dehydrogenase from Yoshida sarcoma ascites cells. On SDS-polyacrylamide gel electrophoresis, the purified preparation (1.19 U/mg protein) appeared homogeneous and its minimum molecular weight was estimated to be 68K daltons. Amino acid analyses indicated a subunit molecular weight of 68,042. Molecular sieve chromatography in the presence of 10% (NH4)2SO4 showed that the molecular weight of the native enzyme was 127K daltons. These values indicate that the native enzyme is composed of two identical subunits. However, the purified enzyme gave 4 protein bands on polyacrylamide gel electrophoresis under non-denaturing conditions, and appeared as a single fraction in the vicinity of the void volume on Ultrogel AcA 34 column chromatography at low salt concentration, indicating that its molecular weight exceeded 200K daltons. These findings indicate that the enzyme tends to aggregate owing to its own physicochemical characteristics. The Km values for IMP and NAD were calculated to be 12 and 25 microM, respectively, and the Ki values for XMP, GMP, and AMP to be 109, 130, and 854 microM, respectively. The purified enzyme showed full activity in the presence of K+, and K+ could be partially replaced by Na+. PCMB inactivated the enzyme, but the activity was completely restored by the addition of DTT. Cl-IMP also inactivated the enzyme and IMP prevented this inactivation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗