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Biomedical subjects

Y Hirachi

Publications and source records attributed to Y Hirachi.

At least 19 recordsLinked to original sources
PubMed1990

[Studies of antigens related to metabolic and growth inhibitions of Staphylococcus aureus L-form].

Metabolic and growth inhibiting activities in immunoglobulin (of anti-S. aureus L-form serum and anti-S. aureus coccal form serum) could be absorbed by cell membranes of S. aureus L-form and its coccal form, respectively. These activities could not be absorbed by cell membrane of Micrococcus luteus, Streptococcus pyogenes or Actinomyces viscosus. These findings suggested the existence of species-specific antigens of cell membrane. The membrane antigens of L-form related to the metabolic and growth inhibiting activities were stable to trypsin, heating and periodate, and were not solubilized by trypsin. A large part of the antigen in a typsin-insoluble membrane precipitate of L-form could be extracted by acetone and the subsequent use of chloroform-methanol (2: 1). A fractionation study of chloroform-methanol extract by using silicic acid calum indicated that more than two components were involved in metabolic and growth inhibiting activities.

Antibodies, Bacterial↗
PubMed1989

Molecular cloning of the Streptococcus mutans gene specifying antigen A.

A gene encoding a Streptococcus mutans surface protein antigen has been isolated from a strain GS-5 gene bank constructed via the Streptococcus-Escherichia coli shuttle vector pSA3. This E. coli recombinant clone, designated 4B2, expressed S. mutans proteins, as shown by Western immunoblot analysis with a specific rabbit antibody to S. mutans surface antigens. Three bands were observed, including a 52-kilodalton (kDa) protein (pI 5.7), a 29-kDa protein (pI 4.2), and a 20-kDa protein usually present in lower amounts. The 52- and 29-kDa proteins both reacted with a monoclonal antibody to S. mutans antigen A, a 29-kDa protein which has been characterized and used as a vaccine for the prevention of induced caries in rodents and monkeys. The 52-kDa protein, but not the 29-kDa protein, showed a capacity to bind to a broad number of carbohydrate polymers. The results from this study suggest that the recombinant 4B2 clone specifies a 52-kDa protein which is a precursor to the 29-kDa antigen A.

Antibodies, Bacterial↗
PubMed1986

Prophage type of recombinants produced by cell fusion between various combinations of lysogenic or non-lysogenic substrains from two Staphylococcus aureus L-forms.

Streptomycin (SM)- or erythromycin (EM)-resistant lysogenic and non-lysogenic substrains were produced from two Staphylococcus aureus L-form strains lysogenic for different prophages, namely, EMT-L (prophage alpha) and 209P (prophage beta). Cells of these L-form substrains were fused in various combinations using polyethylene glycol (PEG), and the frequency of recombinants selected as double resistance to both SM and EM and the prophage types of these recombinants were examined. In all the combinations, the frequency of recombinants was greater when the cells were treated with PEG than when they were not, and the difference was statistically significant (p less than 0.01) in 13 combinations. Combination between the lysogenic SM-resistant EMT-L substrain [EMT(Smr-alpha)] and lysogenic EM-resistant 209P-L substrain [209P(Emr-beta)] and the reverse combination, between 209P(Smr-beta) and EMT(Emr-alpha), resulted in a majority of recombinants harboring prophage beta. The former combination yielded recombinants that all held both prophage alpha and beta.

Bacteriolysis↗
PubMed1986

Effect of the composition of reversion medium on change of Staphylococcus aureus lysostaphin protoplasts to coccal forms and L-forms.

The experimental conditions under which protoplasts of Staphylococcus aureus strain MS353 (pCp) are converted to the coccal or L-form were investigated. Protoplasts prepared by treating coccal MS353 (pCp) strain with Lysostaphin formed various types of colonies (coccal form, L-form and mixed types) in about 50% yield when they were plated on reversion (R) medium consisting of 2% brain heart infusion, 0.5M sodium succinate, 0.01% bovine serum albumin, 20 mM MgCl2 and 0.6% agar. The L-form type colonies with a typical fried-egg appearance that developed on the R medium at an early stage gradually reverted to the coccal form through a mixed type stage in which a high density area first appeared in the periphery of the colony and then spread throughout the colony. The use of modified R medium without MgCl2 or R medium in which 0.5M sodium succinate as an osmotic stabilizer was replaced by 7.5% NaCl resulted in marked delay in the appearance of reverted cells. R medium without bovine serum albumin yielded atypical L-form type colonies, which contained masses of coccal cells with very irregular margins. On the other hand, R medium without MgCl2 but with penicillin G supported development of L-form type colonies at high rate (13-15%) from the inoculated protoplasts.

Culture Media↗
PubMed1985

Cell fusion between L-forms and protoplasts of Staphylococcus aureus.

Mixtures of various combinations of Lysostaphin protoplasts and stable L-forms of Staphylococcus aureus, which have different markers for drug resistance, were treated with polyethylene glycol (PEG) to examine the development of doubly resistant fusion products (fusants). To recover doubly resistant colonies as L-forms, they were incubated in 4.5% NaCl-brain heart infusion (BHI) broth containing penicillin G (PCG) for enrichment culture and cultured in PCG-4.5% NaCl-BHI agar medium (method 1), while to recover doubly resistant fusants as L-forms and coccal forms, they were grown on reversion medium (R medium) which causes reversion of protoplasts or fusants to parent type cells, and then cultured on assay media, i.e., R medium, BHI agar medium or PCG-4.5% NaCl-BHI agar medium (method 2). Under both experimental conditions, doubly resistant fusants developed as L-form cells by PEG treatment of pairs of protoplasts carrying the chloramphenicol (CP)-resistance plasmid and L-forms having chromosomal resistance to streptomycin (SM). In the reverse combinations, i.e., protoplasts showing chromosomal SM-resistance and L-form cells carrying the CP-resistance plasmid, the first method gave no doubly resistant colonies. By the second method, without enrichment culture on R medium, the latter combination gave doubly resistant fusants as L-form, coccal-type and mixed-type colonial forms, while when the PEG-treated mixture was enriched on R medium, fusants were obtained exclusively as the coccal type on either R medium or BHI agar assay medium. Neither of the methods yielded colonies of doubly resistant fusants on PEG-treatment of pairs of protoplasts and L-forms both of which were chromosomal, but with different drug resistances. These results show that PEG-induced cell fusion between protoplasts and L-forms of S. aureus, unlike the fusion between protoplasts or between L-forms, resulted in transfer of the drug resistance controlled by the plasmid to the fusion products. The fusants obtained were L-forms in method 1, and coccal type in the method 2.

Adhesiveness↗
PubMed1982

Liberation of serotonin from rabbit blood platelets by bacterial cell walls and related compounds.

A study was made on the activity of various bacterial cell walls and peptidoglycans to liberate serotonin from rabbit blood platelets. All of the test cell walls or peptidoglycans prepared from 27 strains of 21 bacterial species were shown to cause a marked release of serotonin, regardless of differences in types of peptidoglycan and non-peptidoglycan moieties and in some biological properties. The assay made with the water-soluble "digests" of Staphylococcus epidermidis cell wall peptidoglycans, which were prepared by use of appropriate enzymes, revealed that a polymer of peptidoglycan subunits (a disaccharide-stempeptide) was definitely active in the release of serotonin, but a structural unit monomer was inactive. Among a variety of synthetic muramylpeptides and their 6-O-acyl derivatives, only 6-O-(3-hydroxy-2-docosylhexacosanoyl)-N-acetylmuramyl-L-alanyl-D-isoglutaminyl- L-lysyl-D-alanine was found to hold a strong serotonin-liberating activity.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1982

Isolation of recombinants doubly and triply drug-resistant to streptomycin, tetracycline and chloramphenicol by PEG-induced cell fusion of singly resistant staphylococcus aureus L-forms.

Various combinations of four substrains of Staphylococcus aureus L-form (strain STA-EMT-1), each of which was resistant to one of the following four drugs, streptomycin (SM), tetracycline (TC), chloramphenicol (CP) and erythromycin (EM), were submitted to polyethylene glycol (PEG)-induced cell fusion. PEG-induced cell fusion followed by enrichment culture in the liquid basal medium supplemented with penicillin G resulted in development of recombinants that were doubly drug-resistant to SM and TC, SM and CP, and TC and CP, but no recombinant doubly resistant to EM and TC, was obtained by treatment of a EM-resistant and TC-resistant substrains with PEG. No recombinants resistant to SM, CP and TC could be obtained by treatment of substrains resistant to SM, CP and TC, respectively, with PEG. But recombinants triply resistant to these three drugs were produced by two-step cell fusion; that is by fusion of a recombinant doubly resistant to two of the three drugs with a substrain resistant to the third drug.

Chloramphenicol↗
PubMed1981

Mitogenic effect of cytoplasmic membranes and a cytoplasmic fraction of Staphylococcus aureus L-forms on human peripheral blood lymphocytes.

The cytoplasmic membranes and a cytoplasmic fraction of Staphylococcus aureus L-forms increased the incorporation of [3H]thymidine by human lymphocytes in the presence of fetal bovine serum. Both fractions stimulated cord blood lymphocytes as well as adult peripheral lymphocytes, suggesting the possibility that the observed effect was not due to an antigen-specific reaction, but to an immunologically nonspecific action. The membrane mitogen(s) was resistant to trypsin, although it was partially solubilized by trypsin treatment. The mitogen(s) could not be extracted with a chloroform-methanol mixture (2:1, v/v), although the chloroform-methanol soluble fraction was strongly mitogenic to murine splenocytes. Human serum which was added to the assay system in place of fetal bovine serum definitely suppressed the mitogenic effect of both cytoplasmic membranes and the cytoplasmic fraction, especially the latter.

Cytoplasm↗