Biomedical subjects
Publications and source records attributed to K Fujimura.
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N-(2-Mercapto-2-methylpropionyl)-L-cysteine (SA 96), an antirheumatic agent, and the main metabolite of SA 96, N-[2-methyl-2-(methylthio)propionyl]-L-cysteine (SA 679), were investigated for the effects on vitamin B6 (VB6), metals and skin collagen in rats in comparison with D-penicillamine (D-Pc). SA 96 had no effect on VB6 amount in serum and liver at doses of 30 mg/kg and 150 mg/kg, p.o., for 28 days, but SA 96 as well as SA 679 lowered the level in the liver slightly at a dose of 600 mg/kg. On the other hand, D-Pc lowered the VB6 level markedly both in serum and liver at doses of 150 mg/kg and 600 mg/kg, p.o., for 28 days. SA 96, SA 679 or D-Pc had no effect on urinary VB6 excretion. The degree of complexing of SA 96 as well as SA 679 with pyridoxal-5-phosphate in vitro was very slight as compared with D-Pc. SA 96 and D-Pc increased Cu and Zn excretion in urine, decreased Cu level both in serum and liver, and increased Zn level in serum. However, the degree of these effects of SA 96 on the metals was very slight as compared with D-Pc. SA 96 or SA 679 had no effect on skin collagen, neither soluble nor insoluble collagen, but D-Pc increased soluble collagen markedly. In addition, at a dose of 600 mg/kg, D-Pc decreased insoluble collagen.(ABSTRACT TRUNCATED AT 250 WORDS)
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Messenger RNA for yeast cytosolic polypeptide chain elongation factor 1 alpha (EF-1 alpha) was partially purified from Saccharomyces cerevisiae. Double-stranded complementary DNA (cDNA) was synthesized and cloned in Escherichia coli with pBR327 as a vector. Recombinant plasmid carrying yEF-1 alpha cDNA was identified by cross-hybridization with the E. coli tufB gene and the yeast mitochondrial EF-Tu gene (tufM) under non-stringent conditions. A yeast gene library was then screened with the EF-1 alpha cDNA and several clones containing the chromosomal gene for EF-1 alpha were isolated. Restriction analysis of DNA fragments of these clones as well as the Southern hybridization of yeast genomic DNA with labelled EF-1 alpha cDNA indicated that there are two EF-1 alpha genes in S. cerevisiae. The nucleotide sequence of one of the two EF-1 alpha genes (designated as EF1 alpha A) was established together with its 5'- and 3'-flanking sequences. The sequence contained 1374 nucleotides coding for a protein of 458 amino acids with a calculated mol. wt. of 50 300. The derived amino acid sequence showed homologies of 31% and 32% with yeast mitochondrial EF-Tu and E. coli EF-Tu, respectively.
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The regulating effect of Ca2+ on the association and dissociation of the glycoprotein IIb-IIIa complex from human platelet membranes was determined both for detergent-solubilized and intact plasma membranes. Glycoproteins IIb and IIIa were solubilized from isolated membranes with 0.5% Triton X-100 and incubated in buffers containing ionized calcium, which resulted in the formation of the glycoprotein IIb-IIIa complex. With the addition of EGTA to reduce the ionized calcium content of the solution, the glycoprotein IIb-IIIa complex dissociated. This dissociation was measured by comparing the sedimentation properties of the glycoproteins and by observing the susceptibility of glycoprotein IIb to thrombin-catalyzed hydrolysis. With 10(-3) M Ca2+, glycoproteins IIb and IIIa were resistant to hydrolysis at thrombin concentrations up to 2.4 X 10(-5) M. When the Ca2+ concentration was decreased to less than 10(-4) M by chelation with EDTA or EGTA, glycoprotein IIb was cleaved by thrombin. This increased susceptibility to thrombin hydrolysis at decreasing Ca2+ levels correlated with the increased dissociation of the glycoprotein IIb-IIIa complex as determined by sucrose density centrifugation. Susceptibility to thrombin hydrolysis was also used as a probe to determine the extent to which Ca2+ regulates the formation of the glycoprotein IIb-IIIa complex within membranes. At more than micromolar levels of Ca2+, less than 10% of the membrane-bound glycoprotein IIb was cleaved by thrombin. Increased hydrolysis was observed at decreasing concentrations of Ca2+. Resistance to thrombin hydrolysis was partially regained upon the readdition of Ca2+ to dissociated glycoproteins. These data indicate that micromolar concentrations of Ca2+ exert a direct effect on platelet plasma membrane structure by regulating the intramembranous interactions of glycoprotein IIb.
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A simplified method for an angiotensin-converting enzyme activity assay in biological samples was developed. Samples were incubated with hippurylhistidylleucine, an artificial substrate of angiotensin-converting enzyme. The reaction was terminated by the addition of metaphosphoric acid and liberated hippuric acid in the supernatant was quantitated directly by reversed-phase high-performance liquid chromatography. Tissues were homogenized in the presence of Nonidet-P40, a detergent, and the resulting supernatant was used for the assay of tissue angiotensin-converting enzyme activity by high-performance liquid chromatography. The present procedure made it possible to determine angiotensin-converting enzyme activity in whole blood and the total activity in tissues. A comparative study of angiotensin-converting enzyme activity in plasma, kidney and lung of five experimental animals showed a high degree of variation from species to species.
Crystalline Taka-amylase A, prepared from Takadiastase, was fractionated into four fractions by DEAE-Sephacel and Concanavalin A-Sepharose column chromatography. The relative weight ratio of the fractions was 90 : 4 : 4 : 2. They had similar molecular weights (51,000), amino acid compositions, and hydrolytic activity against soluble starch, but different phenyl maltosidase activities and electrophoretic mobilities on polyacrylamide gel electrophoresis. Three of the fractions mainly had the high mannose type sugar chain with the sugar composition of Man5-GlcNAc2, but the other fraction had only one N-acetylglucosamine residue as the sugar chain. These results suggested that Taka-amylase A was heterogeneous both in the sugar portions and in the polypeptide portions.
The combination effect of chemotherapy and cryosurgery on solid tumor have been evaluated using Ehrlich tumor implanted in hind-limbs of ddN mice. Following regimens were performed. 1) Mitomycin C (MMC) lmg/kg i.p. as a chemotherapeutic agent. 2) cryosurgery -60 degree C for 1.5 minutes. 3) various combination of MMC and cryosurgery. Each average life-span was A) without therapy: 23.8 +/- 4.3 days, B) MMC: 28.0 +/- 4.0 days, C) cryosurgery: 29.5 +/- 6.1 days. Combination therapy which cryosurgery was first performed and then MMC was administered was most effective among various combinations. And the life-span was significantly extended to 38.7 +/- 5.2 days compared with that of each single therapy. When PSK, a immunopotentiator, was added to this regimen, the life-span was extended to 45.0 +/- 9.3 days. The immunological aspects of these regimens were examined by radioisotopic foot-pad assay. Transient increase of cellular immunity was observed in cryosurgery group. The effect of cryosurgery on uptake of anti-tumor agent into tumor tissue were also studied using 3H-labelled 5FU and 14C-labelled 5FU. It was revealed that the uptake rate was significantly increased in tumor margin, but not in tumor center. When the uptake in tumor margin was examined at serial time after cryosurgery, peak of increased uptake was observed at 6 and 12 hours after cryosurgery. Satisfactory response was obtained in clinical application of cryochemotherapy based on these experimental findings.U