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Biomedical subjects

S Yasuda

Publications and source records attributed to S Yasuda.

At least 325 records · Page 18Linked to original sources
PubMed1984

[A case of advanced gastric cancer which disappeared histopathologically after short-time chemotherapy].

Poorly differentiated adenocarcinoma was confirmed by endoscopic biopsy. Anticancer therapy was performed preoperatively, but was discontinued after the second intravenous administration of MFC because she developed nausea, vomiting and pancytopenia. On Jan. 18, 1980, gastrectomy with extended lymph node dissection was performed. Histologically, the excised stomach showed non-specific active ulcer (ul-IV) at the side of the tumor without evidence of residual cancer cells. The cause for the disappearance of the advanced carcinoma remains unknown. Although the dosage of the anticancer chemotherapy was quite small, this treatment may have promoted the regression of the tumor in conjunction with activated antitumor immunity of the host.

Adenocarcinoma↗
PubMed1983

The 245 base-pair oriC sequence of the E. coli chromosome directs bidirectional replication at an adjacent region.

The replication origin of the E. coli K-12 chromosome has been isolated as autonomously replicating molecules(oriC plasmid), and the DNA region essential for replicating function(oriC) has been localized to a sequence of 232-245 base-pairs(bp) by deletion analysis. In this report, the functional role of oriC was analysed by using an in vitro replication system and various OriC+ and OriC- plasmids previously constructed. The results obtained were summarized as follows: (1) The oriC sequence contained information enough to direct bidirectional replication. (2) The actual DNA replication began at a region near, but outside, oriC and progressed bidirectionally. (3) Initiation of DNA synthesis at the specific region required the dnaA-complementing fraction from cells harboring a dnaA-carrying plasmid.

Base Sequence↗
PubMed1983

Identification of calcium-independent myosin kinase with casein kinase II.

A crude myosin fraction from bovine brain has been found to contain a Ca2+-independent myosin kinase that catalyzes the phosphorylation of 20,000-Da light chain of gizzard myosin. The myosin kinase has been separated from the myosin by Sepharose CL-4B gel filtration and purified further by chromatography on phosphocellulose, Sephacryl S-300, and hydroxylapatite. The myosin kinase was found to copurify with casein kinase II and show the same substrate specificity with the casein kinase. These results indicate that the myosin kinase is identical to casein kinase II. The purified myosin kinase catalyzed the preferential phosphorylation of the threonyl residues of 20,000-Da light chains of gizzard and brain myosins. The 17,000-Da light chains of these myosins and the mixed light chains of skeletal and cardiac muscle myosins were not phosphorylated by the enzyme to an appreciable extent.

Amino Acids↗
PubMed1983

Overproduction of Escherichia coli replication proteins by the use of runaway-replication plasmids.

A derivative of the runaway-replication plasmid was constructed. This plasmid, pSY343, has the gene for kanamycin resistance and single sites for EcoRI, BamHI, HindIII, KpnI, and XhoI that can be used as cloning sites without inactivating the kanamycin resistance gene or the replication genes. Three replication genes of Escherichia coli were cloned on the plasmid. The activity of dnaA, dnaZ, and ssb gene products were 200-, 90-, and 60-fold greater, respectively, in the cells containing these plasmids than in normal cells.

Bacterial Proteins↗
PubMed1982

Quantitative determinations of calmodulin in the supernatant and particulate fractions of mammalian tissues.

Although calmodulin is generally regarded as a soluble protein, a considerable amount of calmodulin activity was found to be associated with particulate fractions of mammalian tissues after an extensive washing of the particulate fraction with EGTA. Identity of this particle-bound and EGTA-nonextractable form of calmodulin with soluble calmodulin was established recently (Sobue, K., Yamazaki, R., Yasuda, S., & Kakiuchi, S. (1981) FEBS Lett. 129, 215-219). The particle-associated calmodulin activity was latent to some extent and its unmasking required the presence of nonionic detergent. We have developed an assay method for the soluble and particulate forms of calmodulin in biological samples and, by means of this method, concentrations of calmodulin in rat and bovine tissues were quantitatively determined. In the supernatant, high levels (greater than 10 microM) of calmodulin were found in the testis, pituitary gland, and various areas of brain, intermediate levels (5-10 microM) in the liver, kidney, and spleen. Particulate fractions contained 10-50% of the total calmodulin contents in the tissues. Human erythrocytes contained (2.5 +/- 0.2) microM calmodulin, or (14 +/- 0.9) X 10(4) calmodulin molecules per cell.

Adult↗
PubMed1981

Mechanism of dnaB protein action. I. Crystallization and properties of dnaB protein, an essential replication protein in Escherichia coli.

Purification and crystallization of dnaB protein from Escherichia coli was performed on a large scale by a simple procedure. From 1.5 kg of cells, 520 mg of dnaB protein were obtained in a 58% yield with a purity greater than 99%. The E. coli cells harbor a high copy-number plasmid carrying the dnaB gene and overproduce the enzyme over 200-fold. The subunit molecular weight determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis is 50,000. Based on a native Mr = 290,000 and cross-linking studies that yielded six bands, dnaB protein is judged to be a hexamer, confirming the results of Reha-Krantz, L. J., and Hurwitz, J. (1978) J. Biol. Chem. 253, 4043-4050.

Amino Acids↗
PubMed1981

Purification and properties of Escherichia coli protein i, a prepriming protein in phi X174 DNA replication.

Protein i, one of seven Escherichia coli proteins essential for primosome initiation of DNA chains in the in vitro conversion of single-stranded phi X174 DNA to duplex replicative form, has been purified approximately 15,000-fold to more than 98% purity. The protein is an oligomer of 22,000-dalton subunits migrating as a single electrophoretic band on native, as well as on denaturing polyacrylamide gels. Estimates of a Stokes radius of 41 A, a sedimentation coefficient of 3.5 S, a Mr = 61,000, and a frictional coefficient of 1.57 suggest that native protein i is a highly asymmetric oligomer composed of three identical subunits. About 50 such molecules are present/cell. Cross-linking the protein with dimethylsuberimidate or dimethyladipimidate produced three major bands corresponding to the monomer, dimer, and trimer, as well as two minor bands corresponding to the tetramer and pentamer. Incorporation of 3H-labeled "trimeric" protein i into the prepriming replication intermediate (primosome) occurs at a stage requiring participation of dnaB and dnaC proteins, and follows the actions of proteins n, n', and n". After extension of primers by DNA polymerase III holoenzyme, protein i is not retained in the isolated primosome complex. Thus, protein i is essential in the assembly of a functional primosome, but its precise physiologic role and genetic locus are still unknown.

Amino Acids↗
PubMed1980

Effect of erucic acid on the phospholipid molecular species compositions of the rat heart and liver.

Erucic acid was not incorporated into phosphatidylcholine or phosphatidylethanolamine, but was into diphosphatidylglycerol and sphingomyelin in both the heart and liver of male Wistar rats fed erucic acid for 20 days. A remarkable difference between the heart and liver was found in the molecular species composition of phosphatidylcholine. The 1-stearoyl//2-arachidonoyl species of phosphatidylcholine in the heart was maintained at a higher level in rats fed the erucic acid diet than in rats fed a low fat diet. There was no difference in this molecular species content of cardiac and hepatic phosphatidylethanolamine between rats fed erucic acid and low fat diets. The level of erucic acid incorporated into triacylglycerols and free fatty acids in heart was higher than in the liver.

Animals↗
PubMed1980

Influence of anti-fragment A of diphtheria toxin on passive hemagglutination with antitoxin.

Hemagglutination (HA) and toxin neutralization (TN) tests were used to titrate human and guinea-pig serum specimens taken at various stages of immunization for diphtheria antitoxin. The ratio of HA to TN titers varied significantly depending on the immune status. The ratios and the range of their variations became larger and high values exceeding five were often obtained after repeated booster immunization. Such a high value was proved to be related to the antibody against fragment A (FrA) of diphtheria toxin, since the ratio reduced significantly when anti-FrA was absorbed. Anti-FrA was not produced in children after the basic immunization with diphtheria toxoid and was detected in only one-third of vaccines after the booster injection given after 1 year. It was produced abundantly, however, when booster immunization was repeated. The pattern of production of anti-FrA in guinea pigs was similar to that in humans, when immunized with diphtheria toxoid with adjuvant. No anti-FrA was produced even when the animals were immunized repeatedly with plain diphtheria toxoid.

Animals↗
PubMed1979

Treatment of the femoral shaft fracture with a curved heat-treated COP clover-leaf nail.

The commonly used straight intramedullary nail has certain limitations and disadvantages. Following radiographic and metallurgical studies we have developed a curved heat-treated clover-leaf nail using a newly developed precipitation hardening stainless steel (COP). The nail is bent with a slot on the convex side and the radius of curvature is 115 cm which corresponds to the anatomical antero-lateral convexity of the human femur. The nail has been satisfactory in clinical use since 1971 and has provided not only more stable internal fixation but also allowed fixation of fractures beyond the middle third of the shaft.

Adolescent↗