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Biomedical subjects

T Miwatani

Publications and source records attributed to T Miwatani.

At least 163 records · Page 9Linked to original sources
PubMed1981

Modified Elek test for detection of heat-labile enterotoxin of enterotoxigenic Escherichia coli.

The Elek test was modified for detection of the heat-labile enterotoxin of enterotoxigenic Escherichia coli. A total of 164 strains of E. coli were tested by the modified Elek test, and the results correlated well with those of the Chinese hamster ovary cell assay and passive immune hemolysis. It is concluded that the modified Elek test is a simple and reproducible assay method for identification of E. coli which produce heat-labile enterotoxin, and is suitable for use in clinical laboratories.

Bacteriological Techniques↗
PubMed1981

Genetic labeling of an Ent plasmid that encodes heat-stable enterotoxin of enterotoxigenic Escherichia coli isolated from patients.

Ent plasmids of enterotoxigenic Escherichia coli that encode heat-stable enterotoxin (ST) and both ST and heat-labile enterotoxin (LT) were labeled with a kanamycin- and an ampicillin-resistance transposon, respectively. These transposons were kept stably in the respective Ent plasmids. By monitoring antibiotic resistance we could easily select strains carrying Ent plasmids. Strains carrying the labeled plasmids produced enterotoxins that were immunologically indistinguishable from those produced by the parent strains. Moreover the strain carrying a labeled ST-Ent plasmid produced 16 times more ST than the parent strain.

Ampicillin↗
PubMed1980

Immunological methods for detection of Kanagawa phenomenon of Vibrio parahaemolyticus.

A modified Elek test and an immuno-halo test were developed for detection of the thermostable direct hemolysin produced by Kanagawa phenomenon-positive strains of Vibrio parahaemolyticus. The sensitivity of the modified Elek test was almost the same as that of the Kanagawa phenomenon on Wagatsuma medium, and the results of both reactions correlated very well. The immuno-halo test was a little less sensitive than the modified Elek test. Since the Kanagawa phenomenon on Wagatsuma medium sometimes give false-positive results due to instability of the blood used in the medium, we recommend the immunological techniques described here as reproducible methods for identification of the thermostable direct hemolysin by V. parahaemolyticus.

Culture Media↗
PubMed1980

Value of passive immune hemolysis for detection of heat-labile enterotoxin produced by enterotoxigenic Escherichia coli.

The method of passive immune hemolysis of Evans and Evans (Infect. Immun. 16:604-609, 1977) for detection of heat-labile enterotoxin produced by enterotoxigenic Escherichia coli was modified. A total of 373 strains of E. coli were tested by this method using materials obtained by treating the cells with polymyxin B and rabbit antiserum against cholera enterotoxin, purified by affinity gel column coupled with purified cholera enterotoxin, in N-hydroxyethylpiperazine-N'-2-ethanesulfonic acid buffer (pH 6.7). The results correlated very well with those obtained in an assay with Chinese hamster ovary cells. It is concluded that passive immune hemolysis is useful as a routine clinical method for identifying E. coli strains that produce heat-labile enterotoxin.

Animals↗
PubMed1979

Antagonistic effects of Bacillus natto and Streptococcus faecalis on growth of Candida albicans.

The growth-inhibitory effects of Bacillus natto and Streptococcus faecalis on Canida albicans were investigated. When inoculated into the filtrate of a long-term culture of B. natto strain BN (BN), a stock culture of C. albicans RIMD 0301020 lost its viability completely, whereas C. albicans RIMD 0301011, a fresh isolate from a clinical source, did not. In continuous flow (CF) culture the growth of both strains of C. albicans was suppressed by mixed cultivation with BN. On the other hand, in classical batch culture BN did not suppress the growth of C. albicans. S. faecalis BIO-4R, a multi-drug resistant strain, was also antagonistic to C. albicans RIMD 0301011 but symbiotic with BN in CF culture. These findings suggest that BN in concert with S. faecalis BIO-4R may inhibit the growth of C. albicans in the intestinal tract.

Bacillus↗
PubMed1979

Induction of mutation in Escherichia coli by freeze-drying.

The effect of freeze-drying on phenotypic reversion of amino acid auxotrophy to prototrophy was studied in Escherichia coli. In a radioresistant strain, E. coli H/r 30 (uvr+ exr+), which can repair the deoxyribonucleic acid damaged due to freeze-drying, an increased mutation frequency from auxotrophy to prototrophy was observed with increased time of freeze-drying of the cells. On the other hand, in a radiosensitive strain, E. coli NG 30 (recA), which cannot repair the damaged deoxyribonucleic acid due to a lack of repair enzyme system, no significant reversion occurred, although the survival rate was very low. The rate of phenotypic reversion dut to freeze-drying in both E. coli RIMD 0509109 (uvr+ exr+) and RIMD 0509115 (uvr exr+) was almost the same, indicating that the phenomenon is independent of the uvr character. From these results it is concluded that mutation was induced in E. coli cells during the rehydration when the damaged deoxyribonucleic acid was repaired by exr character of the cells. Thus, we propose that a serious consideration should be paid to the freeze-drying technique to preserve bacterial cells.

Arginine↗
PubMed1979

Mitomycin C stimulates production of a toxin in Shigella species that causes morphological changes in Chinese hamster ovary cells.

Shigella dysenteriae produced a toxin that caused morphological changes in Chinese hamster ovary cells which was different from the neurotoxin (Y. Takeda, K. Okamoto, and T. Miwatani, Infect. Immun. 18:546--548, 1977). It was found that the toxin was produced not only by S. dysenteriae but also by S. flexneri, S. boydii, and S. sonnei. The production of the toxin was stimulated by the addition of 1 microgram of mitomycin C per ml to the culture in the early logarithmic growth phase.

Animals↗
PubMed1979

Purification and partial characterization of heat-stable enterotoxin of enterotoxigenic Escherichia coli.

Heat-stable enterotoxin was purified from a strain of enterotoxigenic Escherichia coli 53402 A-1 from human intestine. The cells were cultured in Casamino Acids-yeast extract-salts medium, and the purification procedure consisted of protamine sulfate treatment of the culture supernatant, ultrafiltration with an Amicon PM-10 membrane, diethylaminoethyl-cellulose column chromatography, hydroxyapatite column chromatography, Bio-Gel P-10 gel filtration, 90% ethanol extraction, and preparative polyacrylamide gel disc electrophoresis. About 300-fold purification was achieved, with a yield of about 12%. However, the homogeneity of the purified heat-stable enterotoxin was not rigorously demonstrated. The purified heat-stable enterotoxin had an absorption maximum at about 275 nm, and its isoelectric point was about 3.90. The molecular weight of the purified heat-stable enterotoxin was ca. 4,000 by Sephadex G-100 gel filtration. The minimum effective dose of purified heat-stable enterotoxin was about 2.5 ng in the suckling mouse assay. The purified heat-stable enterotoxin gave a positive reaction in not only the suckling mouse assay but also the mouse intestinal loop test and the guinea pig skin permeability test.

Electrophoresis, Polyacrylamide Gel↗
PubMed1978

Detection of cholera enterotoxin activity in suckling hamsters.

For detection of cholera enterotoxin activity, suckling hamster, mouse, and rat models were compared. It was found that not only suckling mice but also suckling rats and hamsters were sensitive to cholera enterotoxin. Among these models, suckling hamsters were the most sensitive and gave positive results with about 1/100 the cholera toxin seen in suckling mice and rats.

Administration, Oral↗