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Biomedical subjects

S Mitsuhashi

Publications and source records attributed to S Mitsuhashi.

At least 217 records · Page 12Linked to original sources
PubMed1982

Macrophage activities in sarcoma 180-bearing mice and EL4-bearing mice.

Four types of macrophage activities were studied in sarcoma 180-bearing ICR mice and EL4-bearing C57BL mice. Sarcoma 180 cells grow very slowly and do not metastasize, while EL4 cells grow very rapidly and metastasize rapidly to the liver. Chemotactic activity of macrophages was significantly reduced from an early stage in both sarcoma 180-bearing ICR mice and EL4-bearing C57BL mice as compared with that in normal mice. Digestive activity, which was determined by following O2- production by chemiluminescence measurements was also reduced from an early stage in tumor-bearing mice, whereas no reduction of engulfment activity of microorganisms was observed until an advanced stage in both sarcoma 180-bearing mice and EL4-bearing mice. In contrast enhancement activity of macrophages in the blastogenic response of spleen lymphocytes to bacterial lipopolysaccharide was retained at the normal level at the early stage of the tumor graft and was reduced in later stages. These results suggest that activities of Ia-negative macrophages were at first depressed generally in tumor-bearing hosts and later the activities of Ia-positive macrophages were depressed by factor(s) which might be produced by tumor cells.

Animals↗
PubMed1981

Purification, fine structure and characterization of temperate phages from drug-resistant Staphylococcus aureus.

Three kinds of temperate Staphylococcus aureus phages were differentiated by serological, sedimentation and electron microscopic studies. Phage S1 had a long hexagonal head and a long tail, a density in Cs2SO4 of 1.364 g/ml and belonged to serological group A; phage S2 had a short hexagonal head and a short tail, a density of 1.385 to 1.392 g/ml and belonged to serological group B; phage S3 had a shape similar to phage S2 except for some minor differences, but had a density of 1.416 g/ml and belonged to serological group F. S. aureus MS27 was found to be singly lysogenic for S2. However, S. aureus MS3878 was a doubly lysogenic strain carrying S1 and S2 and S. aureus E169 was a triply lysogenic strain carrying S1, S2 and S3. All these temperate phages showed similarity in shape to typing phages belonging to the same serological group. The temperate S. aureus phages revealed the presence of a hexagonal baseplate with spikes. The burst sizes of phages of S1, S2 and S3 were about 50, 110 and 120 respectively. The DNA from S1, S2 and S3 ranged from 29.4 to 30 megadaltons in size.

DNA, Viral↗
PubMed1981

Immunopotentiating activity of whole cells and mini-cells of Salmonella typhimurium.

Salmonella typhimurium strain 9 produces mini-cells during cell proliferation. Mini-cells are viable but cannot proliferate since they do not contain chromosomal DNA. Effects of whole cells and mini-cells of S. typhimurium on the immune responses were investigated, with the following results. Phagocytosis of peritoneal macrophages was enhanced by in vivo stimulation of both whole cells and mini-cells. Cellular immunity against L1210 cells (mouse leukemia cells) and Sarcoma 180 cells was also enhanced by both whole cells and mini-cells. Mini-cells slightly stimulated in vitro blast cell transformation of normal mouse lymphocytes. Whole cells of S. typhimurium induced antibody-forming cells to produce IgG of higher affinity but mini-cells did not. Mini-cells were not directly cytotoxic for normal lymphocytes or L1210 cells.

Adjuvants, Immunologic↗
PubMed1981

Drug resistance and R plasmids in Bordetella bronchiseptica isolates from pigs.

A total of 207 strains of Bordetella bronchiseptica isolated from pigs in 1978 and 1979 were tested for drug resistance and for the properties of their R plasmids. Apart from intrinsic resistance to spectinomycin, single (sulfadimethoxine), double (sulfadimethoxine and streptomycin), andt riple (sulfadimethoxine, streptomycin, and ampicillin) resistance were found in 54.1%, 1.0%, and 15.9% of the strains, respectively. All of the triple-resistance determinants were associated with mercury resistance and were conjugative. pBB1, one of these R plasmids, was identified as Fi- (F) and Spp- (no suppression of phage multiplication) type, and as a member of incompatability group IncP. The single- and double-resistance determinants were nonconjugative. pBB2, one of the double-resistance determinants, was mobilized by an R plasmid, RP4, with the high efficiency of 80% and at a frequency of 3.3% without cotransfer of RP4. The molecular weight of pBB1 and pBB2 was estimated at 36 X 10(6) and 13 X 10(6) daltons, respectively, by electron microscopy and agarose gel electrophoresis. pBB1 had five cleavage sites for EcoRI endonuclease, and four sites for HindIII. pBB2 had two EcoRI sites, one HindIII, and one BamHI site. Cells carrying pBB1 or pBB2 produced enzymic activity tha inactivated streptomycin in the presence of ATP.

Animals↗
PubMed1981

Spontaneously induced suppressor cells in vitro: nonspecific suppression of in vitro antibody formation.

Nonspecific suppressor cells were induced during in vitro culture of normal mouse spleen cells (SPC) using the Marbrook culture system. The suppressor cells inhibited both the primary and secondary antibody-formation responses antigen nonspecifically in vitro, and both IgM- and IgG-responses were inhibited. The supernatants from suppressive precultured cells were not suppressive. The suppressor cells also inhibited the response of allogeneic SPC beyond H-2 compatibility. The induction of the suppressor cells did not require the presence of antigen but required fetal calf serum (FCS) or both FCS and 2-mercaptoethanol (2-ME). The suppressor cells were generated from the nylon-wool adherent, radiation-sensitive T cell population. On the other hand, the suppressor cells were nylon-wool nonadherent, relatively radiation-sensitive T cells. Actively antibody-producing cells were not affected by the suppressor cells. The suppressor cells inhibited the mitogenic responses of normal SPC to phytohemagglutinin-P (PHA), bacterial lipopolysaccharide (LPS) and concanavalin A (Con A). The suppressor cells themselves inhibited the growth of EL4 cells (T-cell leukemia of C57BL/6 mouse origin) and MOPCll cells (B cells, plasmacytoma of BALB/c mouse origin) even at a low effector-to target cell ratio (E:T ratio = 1:1), but did not kill these tumor cells. These results indicate that the target cells of the suppressor cells are both T and B cells, and that the mechanism of action of the suppression is either inhibition of proliferation or inhibition of early events in the course of the immune response.

Animals↗
PubMed1981

Drug resistance and R plasmids of Escherichia coli strains isolated from pigs, slaughterers, and breeders of pigs in Japan.

We isolated 1,120 drug-resistant Escherichia coli strains from pigs, slaughterers, breeders of pigs, and urban residents and examined their drug resistance. With reference to resistance to tetracycline (Tc) chloramphenicol (Cm), streptomycin (Sm), and sulfanilamide (Su), Tcr, Smr, and Sur strains were most frequently isolated from pigs (57.9%), followed by slaughterers (50.2%) and breeders (42.4%). By contrast, the isolation frequencies of Tcr, Smr, and Sur strains from urban residents were low (12.0%). The isolation frequencies of R plasmids from resistant strains were more than 50% in the case of pigs, slaughterers, and breeders, whereas they were only 13.8% in urban residents. Kanamycin-resistant strains were frequently isolated from pigs (40.3%), slaughterers (22.6%), and breeders of pigs (25.4%), but seldom (only 3.4%) from urban residents. With ampicillin resistance, the frequencies of strains from pigs, slaughterers, breeders, and urban residents were 30.0, 21.5, 5.6, and 13.8%, respectively. R plasmids specifying these latter resistances were frequently seen from pigs (24.0%), slaughterers (23.6%), and breeders (21.1%), but they were not isolated from urban residents. The results suggest that the porcine gut can function as a reservoir of antibiotic resistance plasmids which can then be directly transferred to humans, with the highest frequency of such plasmids appearing in people in the most immediate contact with these animals.

Abattoirs↗
PubMed1981

Synergistic activities of fortimicin A and beta-lactam antibiotics against Pseudomonas aeruginosa.

The inhibitory and bactericidal activities of fortimicin A (FTM-A) alone against Pseudomonas aeruginosa were compared with those of FTM-A in combination with beta-lactam antibiotics. As tested by the checkerboard method, most beta-lactam antibiotics tested had synergistic effects on the inhibitory activity of FTM-A against one strain of P. aeruginosa. Addition of a sublethal concentration of carbenicillin resulted in a significant increase in the rate of bacterial killing of FTM-A against P. aeruginosa. The antibacterial activity of FTM-A against 50 gentamicin-susceptible and 50 gentamicin-resistant clinical isolates of P. aeruginosa was clearly enhanced by addition of a subinhibitory concentration of carbenicillin or piperacillin.

Aminoglycosides↗
PubMed1981

Beta-lactamase stability and antibacterial activity of cefmenoxime (SCE-1365), a novel cephalosporin.

Cefmenoxime, a new cephalosporin antibiotic, has been shown to be stable to a Staphylococcus aureus penicillinase and R plasmid-mediated type I and type IV penicillinases. It was also resistant to hydrolysis by most cephalosporinases, but was susceptible to hydrolysis by a Proteus vulgaris beta-lactamase. Cefmenoxime was active against cephaloridine-resistant species, except Pseudomonas aeruginosa, which was moderately resistant to cefmenoxime. Cefmenoxime was an inducer of P. vulgaris beta-lactamase biosynthesis, but 1 microgram or more of the drug per ml, which inhibits most of the clinical isolates of P. vulgaris, was required for the production of detectable amounts of the enzyme. Cefmenoxime was a strong competitive inhibitor of beta-lactamases of Enterobacter cloacae, Citrobacter freundii, P. aeruginosa, and Serratia marcescens, but it did not inhibit penicillinases in spite of its resistance to hydrolysis.

Anti-Bacterial Agents↗
PubMed1981

Immunological properties of beta-lactamases that hydrolyze cefuroxime and cefotaxime.

Antiserum against purified beta-lactamase from Proteus vulgaris GN7919 cross-reacted with beta-lactamases produced by strains of Pseudomonas cepacia in a neutralization test. Anti-P. cepacia beta-lactamase serum, however, did not show any cross-reactions with P. vulgaris beta-lactamases. Each of these enzymes can hydrolyze cefuroxime and cefotaxime.

Animals↗
PubMed1981

Tn2001, a transposon encoding chloramphenicol resistance in Pseudomonas aeruginosa.

We isolated a new transposon, Tn2001, from the group P-2 plasmid Rms159-1 in Pseudomonas aeruginosa. Tn2001-encoded chloramphenicol resistance did not result from the formation of chloramphenicol acetyltransferase. Tn2001 was transposable between temperate phages and conjugative and nonconjugative plasmids belonging to various incompatibility groups, including P-1, P-3, P-4, P-5, P-7, and P-8 in P. aeruginosa. Transposition occurred independently of the general recombination ability of the Pseudomonas host, and its frequency varied between 10(-1) and 10(-8), depending upon the donor and recipient replicons. Tn2001 transposition also occurred in a recombination-deficient strain of Escherichia coli. Agarose gel electrophoresis and electron microscopic observations revealed that Tn2001 could transpose to different sites in the RP4 replicon and that the transposed deoxyribonucleic acid fragment was 2.1 kilobases long.

Chloramphenicol↗
PubMed1981

A mutant defective in partitioning of composite plasmid Rms201.

Escherichia coli harboring mutant plasmids defective in maintenance stability (from the conjugative plasmid Rms201) showed a wide distribution of ampicillin resistance levels, as well as increased frequency of plasmid loss from the cell. The amounts of covalently closed circular deoxyribonucleic acid of mutant plasmid Rms268 and parental plasmid Rms201 per chromosome were 5.3 and 6.1%, respectively. The beta-lactamase activities of strains W3630(Rms268) and W3630(Rms201) were 0.56 and 0.44 U/mg of protein, respectively. Frequency of plasmid loss from W3630(Rms268) was about 0.8 to 1.2% per cell generation, 100 times more than that of the wild-type strain. Ampicillin resistance levels of the colonies harboring the mutant plasmid showed a wide distribution, from low (100 micrograms/ml) to high (1,600 micrograms/ml). A miniplasmid (pMS268) with a mass of 7 X 10(6) daltons and encoding ampicillin resistance was isolated from Rms268. Frequency of pMS268 loss from W3630(pMS268) was about 0.8 to 1.9% per cell generation. W3630(pMS268) also showed a wide range of distribution in the levels of ampicillin resistance. These results indicated that the copies of Rms268 in E. coli did not segregate evenly between daughter cells at cell division and that the gene involved was located on the miniplasmid.

Ampicillin↗
PubMed1981

Regular segregation of composite plasmid Rms201.

Copy number mutants Rms201ts15 and Rms201ts16 were isolated at 30 degrees C from a temperature-sensitive replication mutant (Rms201ts14) of the conjugative plasmid Rms201. The numbers of plasmids per chromosome of ML1410(Rms201ts14), ML1410(Rms201ts15), and ML1410(Rms201ts16) grown at 30 degrees C were 2.2, 7.4, and 20, respectively. The synthesis of covalently closed circular plasmid deoxyribonucleic acid stopped in Rms201ts14, Rms201ts15, and Rms201ts16 immediately after a "shift-up" in temperature (42 degrees C). At 42 degrees C, antibiotic-sensitive derivatives appeared after a certain lag time: the lag times of ML1410(Rms201ts14), ML1410(Rms201ts15), and ML1410(Rms201ts16) were 2.5, 5, and 6.8 generations, respectively. After these times, plasmid-positive cells in the populations decreased at a rate of about 50% per generation in all of the mutants. From these results we conclude that plasmid segregation (partition) of Rms201 occurs by regular segregation (partition).

Ampicillin↗