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Biomedical subjects

S Yasuda

Publications and source records attributed to S Yasuda.

At least 343 records · Page 19Linked to original sources
PubMed1979

A case of bilateral primary posterior dislocation of the shoulder.

We present a case of bilateral primary dislocation of the shoulder, which was treated operatively on the left and conservatively on the right side. Primary posterior dislocation of the shoulder is rarely seen and bilateral case is extremely rare. For the diagnosis it is essential to have a knowledge of this dislocation. As to roentgenographic examination, the axillary projection is most helpful but can't be routinely taken because of severe pain and limited abduction of the shoulder. So special roentgenographic techniques are necessary.

Adult↗
PubMed1978

Murein-lipoprotein of Escherichia coli: a protein involved in the stabilization of bacterial cell envelope.

Two independent mutants of Escherichia coli lacking murein-lipoprotein have been found. One mutant whose mutation was named lpo was subjected to detailed analyses. The absence of both bound and unbound lipoproteins was shown by electrophoretic analysis of 14C-arginine labelled membrane proteins of the mutant. Nor was serologically cross-reacting material detected in the mutant by the Ouchterlony-method. Sequestering magnesium from mutant cell suspensions by ethylenediaminetetraacetic acid caused cell lysis, which was prevented in the presence of 0.5 M sucrose. Incubation in culture media at a very low level of magnesium resulted in the formation of blebs in the mutant. Examination of mutant cells by electron microscopy showed that the outer membrane of the mutant was uneven with small irregular protuberances, some of which pinched off forming vesicles of various sizes. Phosphotungstate used for negative-staining penetrated into the periplasmic space of the mutant cells. The mutants leaked a considerable fraction of their periplasmic enzymes. These physiological and morphological alterations in the lipoproteinless mutant suggest that murein-lipoprotein helps to maintain the outer envelope structure by connecting the outer membrane with murein so that the outer membrane may fulfil its physiological functions as a barrier to the environment.

Electrophoresis↗
PubMed1977

Cloning and mapping of the replication origin of Escherichia coli.

The replication origin of Escherichia coli has been cloned on a nonreplicating DNA fragment coding for ampicillin resistance. This recombinant DNA, named pSY211, replicates depending on the presence of the replication origin and can be recovered as a closed circular plasmid DNA of 10.7 megadaltons (Mdal). A restriction map has been constructed. EcoRI cleaves pSY211 into two fragments: one is the ampicillin fragment of 4.5 Mdal and the other is a chromosomal fragment of 6 Mdal and contains the origin. The 6 Mdal EcoRI fragment has four BamHI sites, three HindIII sites, and one Xho I site. A mutant of pSY211 has been isolated which is lacking two BamHI fragments of the chromosomal fragment. In recA hosts, pSY211 is lost at a high frequency. In recA+ hosts, pSY211 is integrated into the chromosome due to nucleotide sequence homology between pSY211 and the replication origin of the E. coli chromosome. The integration site has been mapped. We conclude that the replication origin is located at a site between uncA and rbsK, at about 83 min on the genetic map of E. coli.

Base Sequence↗
PubMed1977

On the process of cellular division in Escherichia coli: a mutant of E. coli lacking a murein-lipoprotein.

A mutant of E. coli lacking a specific outer membrane lipoprotein was found. Both the free and the bound form have been lost in this mutant. No material that cross-reacted with antiserum against lipoprotein was detected by the Ouchterlony test. The mutant was defective in producing mRNA active for lipoprotein synthesis. The mutation leading to the loss of lipoprotein synthesis, referred to as lpo, seems to have arisen during production of an F'. The map position of lpo was at 36.5 min on the E. coli K12 map, in the order man, uidA, lpo, aroD, pps. The lpo mutant grew and divided normally and remained susceptible to bacteriophages lambda, phi80, P1, P2, the T series, and f1, f2, and MS2 in its male derivatives. The mutant was hypersensitive to EDTA and cationic dves and somewhat sensitive to detergents. There was considerable leakage of periplasmic enzymes but passive transport of beta-galactoside was unchanged. These physiological characteristics of the mutant suggest that lipoprotein is involved in maintaining the integrity of the outer envelope structure, by bridging the outer membrane and murein, but not in the vital processes of growth and division.

Cell Division↗
PubMed1977

Suppression of delayed type hypersensitivity induction to sheep red blood cells by concanavalin A in mice.

An examination was carried out on the in vivo effect of concanavalin A (Con A) on the induction of delayed-type hypersensitivity (DTH) to heterologous erythrocytes in mice. DTH induction was suppressed by an intravenous injection of 100 microng of Con A 1 day before, or simultaneously with immunization. This suppression was mediated by Con-A-activated spleen cells, and also by their cell-free extracts. However, this suppressive effect was abrogated by absorption of cell-free extracts with immunoadsorbent composed of rabbit anti-mouse thymocyte serum (ATS), indicating that suppressive factors for DTH induction make up one of the components extractable from Con-A-activated T cell population.

Animals↗
PubMed1976

Further purification and characterization of T4 endonuclease V.

T4 endonuclease V, which is involved in repair of ultraviolet-damaged DNA, has been purified 3600 fold from T4D-infected Escherichia coli. The enzyme shows optimal activity at pH 7.2 and does not require added divalent ions. Endonuclease V attacks both native and heat-denatured DNA provided that the DNA has been irradiated, and the enzyme activity is dependent on the dose of ultraviolet irradiation. The rate and the extent of the reaction are greater with irradiated native DNA although the Km values for the two types of DNA are the same (2.25 - 10(-5) M). The enzyme is readily inactivated by heat and is sensitive to p-chloromercuribenzoate. Endonuclease V-treated irradiated DNA is degraded by spleen phosphodiesterase only when the DNA has been treated with alkaline phosphatase, suggesting that the enzyme produces 5'-phosphoryl termini.

Alkaline Phosphatase↗
PubMed1976

Repair of DNA damaged by methyl methanesulfonate in bacteriophage T4.

A highly purified preparation of T4 endonuclease V does not degrade DNA alkylated with methyl methanesulfonate, and the methyl methanesulfonate sensitivity of T4 wild type and x mutant is not affected by the v mutation. Thus, T4 endonuclease V, the v gene product, does not seem to be involved in a repair or an abortive repair of methyl methanesulfonate-damaged T4 DNA. The x and y genes of T4 and the polA and the uvrD genes of Escherichia coli are concerned with the repair of methyl methanesulfonate-induced damages in T4 DNA. Since effects of the polA and the x or y mutations are additive, it is supposed that there are at least two pathways for the repair of methyl meth-anesulfonate-damaged T4 DNA, one controlled by the x and the y genes and the other in which E. coli DNA olymerase I is involved. The partial suppression of the x gene mutation at high temerature was also demonstrated.

Coliphages↗
PubMed1975

Enzymic mechanism of excision-repair in T4-infected cells.

Excision of pyrimidine dimers from ultraviolet-irradiated DNA in a cell-free system of Escherichia coli infected with bacteriophage T4 consists of two different steps, one to induce a single-strand break at a point close to a pyrimidine dimer and the other to release dimer-containing nucleotide from the DNA. The enzymes responsible for these steps were isolated and the reactions were characterized; T4 endonuclease V introduces a break at the 5' side of a dimer and 5' in equilibrium 3' exonucleases, which are also induced by T4, act at the break to excise dimer-containing nucleotides. We isolated temperature-dependent v mutants, which exhibit increased sensitivity to UV at 42 degrees C but not at 30 degrees C, and found that the mutants induce temperature-sensitive T4 endonuclease V, indicating that the v gene of T4 is indeed the structural gene for T4 endonuclease V and that the enzyme is responsible for the first step of excision-repair. A possible mechanism of excision-repair in T4-infected cells is discussed.

Coliphages↗