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Biomedical subjects

S Mitsuhashi

Publications and source records attributed to S Mitsuhashi.

At least 235 records · Page 13Linked to original sources
PubMed1981

Purification and properties of cephalosporinase from Pseudomonas aeruginosa.

Cephalosporin beat-lactamase (cephalosporinase, CSase) was purified from a strain of Pseudomonas aeruginosa resistant to beta-lactam antibiotics. The purified enzyme preparation gave a single protein band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and its molecular weight was about 34,000. The specific activity was 49.7 mumoles/minute/mg of protein of the purified enzyme for the hydrolysis of cephaloridine. The optimal pH and optimal temperature were about 8.0 and 40 degrees C, respectively. Its isoelectric point was 8.7. The enzyme activity was inhibited by iodine, some divalent ions, and some semisynthetic beta-lactam antibiotics, including cephamycin derivatives such as moxalactam and YM09330. Mouse antiserum obtained against the purified enzyme showed no cross-reaction with other types of beta-lactamase in neutralization test.

Anti-Bacterial Agents↗
PubMed1981

Properties of cephalosporinase from Proteus morganii.

The cephalosporin beta-lactamase (cephalosporinase) was purified from a strain of Proteus morganii which showed resistance to cephalosporins. The optimal pH was about 8.5, and the optimal temperature was 40 degrees C. The isoelectric point was 8.7 and the molecular weight was estimated to be about 41,000 from sodium dodecyl sulfate-acrylamide gel electrophoresis. The enzyme activity was inhibited by cloxacillin, ampicillin, carbenicillin, cefuroxime, cefotaxime, ceftizoxime (FK749), cefmenoxime (SCE-1365), cefoxitin, cefmetazole, YM09330 and moxalactam (6059-S), but not by clavulanic acid or CP-45899. The beta-lactamase also hydrolyzed cephaloridine, cefazolin, cephalothin, cephalexin, cefotiam, cefamandole and benzylpenicillin. These results suggest the possibility that the properties of beta-lactamases may be characterized by measuring the kinetic parameters of the enzyme toward newly-introduced beta-lactam antibiotics and beta-lactamase inhibitors.

Anti-Bacterial Agents↗
PubMed1981

Enzymatic adenylylation of spectinomycin by Acinetobacter calcoaceticus subsp. anitratus.

Spectinomycin (SPC) was inactivated in the presence of adenosine-5'-triphosphate and magnesium ion by an enzyme preparation made from Acinetobacter calcoaceticus subsp. anitratus GN12313 resistant to both SPC and streptomycin. The structure of the inactivated SPC was found to be the adenylylated product of the hydroxy group on C-9 of the actinamine moiety.

Acinetobacter↗
PubMed1981

Acceleration of allogeneic antitumor immunity with immune RNA in vitro and T-cell suppression by L1210 tumor bearer spleen cells.

RNA fractions extracted from the spleens of immunized animals prepared against L1210 leukemia cells can transfer allospecific cell-mediated immunity both in vitro and in vivo. Both preculture of nonsensitized lymphocytes prior to the treatment with immune RNA and additional culture of lymphocytes after 1-hr treatment with immune RNA enhance the growth-inhibitory activity of immune RNA-treated lymphocytes. Preculture for 5 hr and additional culture for 24 hr are sufficient for maximal enhancement of the growth-inhibitory activity. There is no significant difference in inhibition between lymphocytes treated with immune RNA for 1 hr and 24 hr. The growth inhibition by lymphocytes is augmented proportionally to the increase in the dose of immune RNA in vitro but not in vivo. In mice given i.p. injections of immune RNA-treated syngeneic spleen cells (before or after inoculation with L1210 cells), a significant prolongation of the mean survival time [27.0 +/- 5.4 (S.D.) days, 0.05 < p < 0.1] was not achieved when compared with control mice (21.4 +/- 1.6 days). Evidence is presented that suppressor cells in the spleens of L1210-bearing mice are involved in preventing effector cell function in vivo. The present study revealed that 8 X 10(3) and 5 X 10(5) suppressor cells were sufficient to inhibit completely the activity of immune RNA-treated effector cells in vitro and in vivo, respectively. Suppressive activity was abolished by treatment with anti-Thy 1.2 serum and complement and partially abolished with irradiation (1500 R). The suppressor cells belonged to a radiation-sensitive T-cell population. The limited activity of immune RNA in vivo is probably due to the destruction of immune RNA by RNase present in the host plasma and tissues and the acquisition of suppressor cells which inhibits nonadherent peritoneal exudate cell activity in the animal.

Animals↗
PubMed1981

Induction of IgM memory with RNA from the spleens of immunized mice.

Ribonucleic acid (immune RNA, iRNA), extracted from the spleens of mice immunized with sheep red blood cells (SRBC), induced specific immunological memory. The humoral immune responses of iRNA-treated animals were compared with in vivo and in vitro primary and secondary responses, using the haemolytic plaque-forming cell (PFC) assay. IgM antibody formation was markedly higher in iRNA-treated than in any other mice. The effect of iRNA was antigen-specific and similar materials from non-immunized mice had no activity.

Animals↗
PubMed1981

Cefotaxime: binding affinity to penicillin-binding proteins and morphological changes of Escherichia coli and Pseudomonas aeruginosa.

The mechanism of action of a new cephalosporin 7-[2-(2-amino-4-thiazolyl)-2-methoximino]-acetamido cephalosporanate (cefotaxime), was studied with respect to its binding affinities to penicillin-binding proteins (PBPs), and morphological changes of bacteria treated by cefotaxime in vitro. Cefotaxime showed especially high affinity (compared with that pf penicillin G) for Escherichia coli PBP-1A, -1Bs, -3 and -4'and low affinities for PBP-2, -4, -5 and -6. Similar results were obtained with Pseudomonas aeruginosa, in which this compound showed high affinities for PBP-3, -1A, -1B and -2. These results are compatible with morphological observations that at concentrations near its minimum inhibitory concentration or more, this antibiotic induced the formation of filamentous cells of Escherichia coli and Pseudomonas aeruginosa. At higher concentrations or after prolonged incubation, it induced lysis of the cells.

Bacterial Proteins↗
PubMed1981

Transduction of amikacin, gentamicin and tobramycin resistance in Pseudomonas aeruginosa with phage F 116 and AP 19, a new wildtype phage.

Amikacin-, tobramycin-, gentamicin- as well as carbenicillin-resistance has been found to be transducible, in various combinations of spectra both with the phage F 116 propagated on an Amikacin-resistant wild-type strain of Pseudomonas aeruginosa (No. BE 11) and with the phage AP 19 isolated from a different Amikacin-resistant strain (No. 578). Both strains were found to transfer Amikacin-resistance genes presumably by conjugation thus possessing an R plasmid coding for multiple antibiotic resistance. Evidence is presented that classical as well as wild-type phages may acquire and transmit antibiotic resistance genes among pseudomonads. This is particularly significant in view of the importance to preserve Amikacin as an effective reserve antibiotic for treatment of poly-resistant infections including those caused by P. aeruginosa.

Amikacin↗
PubMed1980

Purification and properties of chromosomally mediated beta-lactamase from Citrobacter freundii GN7391.

Both a penicillinase and a cephalosporinase are present in a strain of Citrobacter freundii (GN7391) resistant to beta-lactam antibiotics. The penicillinase was identical to the type Ia penicillinases (Type III by Richmond classification), mediated by Rms212 and R-TEM. A cephalosporinase, typical of enterobacteriaceae chromosomal beta-lactamase (Type I by Richmond classification), was purified from the strain. It gave a single protein band on polyacrylamide gel electrophoresis and immunoelectrophoresis; the pI was 8.6 and its molecular weight was approximately 38 000. Cysteine was not found among its amino acids. The specific activity was 388 units (mg protein)-1 for the hydrolysis of cephaloridine, and the optimal pH was 8.0. Rabbit antiserum obtained against the purified enzyme showed cross-reaction with cephalosporinases produced by strains of Enterobacter cloacae in a neutralization test.

Amino Acids↗
PubMed1980

In vitro antibacterial activity of AM-715, a new nalidixic acid analog.

AM-715 [1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-3-quinolinecarboxylic acid] is a new nalidixic acid analog. AM-715 has a broad spectrum of antibacterial activity against gram-positive and gram-negative bacteria. The antibacterial activity of AM-715 was greater than those of pipemidic acid and nalidixic acid. AM-715 had higher antibacterial activity against Pseudomonas aeruginosa than did gentamicin. Most nalidixic acid-resistant bacteria were susceptible to AM-715, and cross-resistance was not observed between AM-715 and various antibiotics. The minimal concentration of AM-715 required to inhibit the growth of 75% of the total number of clinical isolates was as follows: Escherichia coli, 0.04 mug/ml; Klebsiella pneumoniae, 0.1 mug/ml; Serratia marcescens, 0.88 mug/ml; Enterobacter spp., 0.076 mug/ml; Staphylococcus aureus, 1.10 mug/ml; P. aeruginosa, 0.38 mug/ml; and nalidixic acid-resistant strains of gram-negative bacteria, 0.62 mug/ml. AM-715 at minimal inhibitory concentrations or at slightly higher concentrations had bactericidal activity against various species of bacteria. The effect of inoculum sizes on minimal inhibitory concentrations and minimal bactericidal concentrations of AM-715 against gram-negative bacteria was smaller than on those of pipemidic acid and nalidixic acid. The dose-response curve of AM-715 indicated a steep gradient, and the 50% inhibited doses of AM-715 were 0.014 mug/ml against E. coli ML4707 and 0.21 mug/ml against P. aeruginosa NC-5.

Anti-Bacterial Agents↗
PubMed1980

In vitro and in vivo antibacterial activity of KW1070, a new aminoglycoside antibiotic.

KW1070, a new aminoglycoside antibiotic with the novel aminocyclitol, fortamine, has a broad spectrum of activity in vitro and in vivo against gram-positive and gram-negative bacteria. The minimum inhibitory concentrations of KW1070 are similar to those of kanamycin against aminoglycoside-susceptible strains, slightly less than those of gentamicin or 3',4'-dideoxykanamycin B. Minimal bactericidal concentrations were found to be near minimal inhibitory concentrations. KW1070 was active in vitro against many aminoglycoside-resistant bacterial strains that possess aminoglycoside-inactivating enzymes, particularly AAC(6'), AAC(2'), AAD(2''), and APH(3'). The activities of KW1070 in mice infected with Staphylococcus aureus, Escherichia coli, Proteus sp., and Serratia marcescens compared favorably with the activities of amikacin and kanamycin; KW1070 was also singificantly active in mice infected with resistant strains bearing the aminoglycoside-inactivating enzymes listed above.

Acetylation↗
PubMed1980

In vitro and in vivo antibacterial activity of AB206, a new naphthyridine derivative.

AB206 (5,8-dihydro-5-methoxy-8-oxo-2H-1,3-dioxolo-4,5-g quinoline 7-carboxylic acid) is a novel antibacterial agent structurally related to nalidixic acid. AB206 has potent antibacterial activity against clinical isolates of gram-negative bacteria and is 4 to 18 times more active than nalidixic acid. AB206 inhibited the growth of Staphylococcus aureus and Pseudomonas aeruginosa, which were resistnat to nalidixic acid. Cross-resistance was not observed between AB206 and various antibiotics, and most bacterial strains resistant to nalidixic acid were susceptible to AB206. AB206 showed bactericidal activity against Escherichia coli, Proteus, Klebsiella pneumoniae, and P. aeruginosa. Chemotherapeutic effects after oral administration of AB206 in mice experimentally infected with E. coli, K. pneumoniae, and Proteus morganii showed that AB206 was two to four times more potent than nalidixic acid.

4-Quinolones↗
PubMed1980

Purification and properties of a new beta-lactamase from Pseudomonas cepacia.

An inducible beta-lactamase was purified from a beta-lactam antibiotic-resistant strain (GN11164) of Pseudomonas cepacia. The purified enzyme preparation gave a single protein band on polyacrylamide gel electrophoresis. The specific enzyme activity for the hydrolysis of cephalothin as a substrate was 314.5 U/mg of protein. The optimal pH was about 8.0, and the optimal temperature was 45 degrees C. The isoelectric point was 9.3, and the molecular weight was estimated to be about 22,000 to 24,000 from gel filtration on a Sephadex G-200 column and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme activity was inhibited by iodine, p-chloromercuribenzoate, clavulanic acid, CP 45899, and cloxacillin. The beta-lactamase showed a unique substrate profile by hydrolyzing most of the cephalosporins, including cefuroxime, cefotaxime (HR 756), ampicillin, and penicillin G, at a high rate.

Cell-Free System↗