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Biomedical subjects

E Yoshizawa

Publications and source records attributed to E Yoshizawa.

7 recordsLinked to original sources
PubMed1993

[Microbiological determination of netilmicin using a thin-layer chromatography scanner].

We presented a new colorimetric bioassay of aminoglycoside antibiotics, which were represented by netilmicin (NTL) in this study, based on the discoloration of thymolphthalein (TP) in paper (indicator-disc) by carbon dioxide produced by Bacillus subtilis. To evaluate the amount of the carbon dioxide, the following experiment was carried out. One milliliter of B. subtilis suspension containing 4.5 x 10(7) colony forming units/ml, 1 ml of nutrient broth, 0.9 ml of 0.1 M phosphate buffer (pH 8.0) and 0.1 ml NTL sample solution were added to an incubation container, which was then placed in a water-bath (37 degrees C) for 3 hours. The oxygen concentration in the head space of flask was determined using gas-chromatograph. The dose-response curves showed good correlation between amounts of NTL and carbon dioxide produced by B. subtilis. The indicator-disc containing TP and sodium hydroxide was placed into the Reacti-flask and then incubated in the same manner as described above. After incubation, concentration of blue colored TP was determined using a TLC scanner. The discoloration of blue color to white showed the proportionality between NTL concentrations and the degrees of discoloration of TP. The method can accurately measure NTL levels down to 2.5 micrograms/ml in water using 0.1 ml samples, and should be adequate for rapid bioassay.

Bacillus subtilis↗
PubMed1992

[Fluorescence polarization immunoassay of isepamicin in blood spotted on filter paper].

A simple method has been developed for the determination of the aminoglycoside antibiotic isepamicin (ISP) in whole blood, using dried blood spots (DBSs) on filter-paper. ISP in the DBSs were recovered most effectively in 0.5 M Na2HPO4-NaH2PO4 buffer (pH 7) by incubation for 30 minutes at 35 degrees C in an ultrafiltration tube. The eluates from the DBS papers were centrifuged at 3,000 x g for 10 minutes. The clear, colorless filtrates were transferred to an Abbott TDx cartridge for measurement by the fluorescence polarization immunoassay. The lower limit for the quantitative determination of ISP in the DBS was 2.5 micrograms per ml of whole blood. The method permits a simple collection of blood at a microliter level and should prove particularly useful for therapeutic drug monitoring of ISP in blood at effective levels in pediatric and geriatric patients.

Animals↗
PubMed1989

[Determination of isepamicin in the eluates from the dried blood spots on filter paper for monitoring of blood levels in a guinea-pig].

In general, collection of serial blood samples from small experimental animals is difficult in terms of sampling site and operation technique. To overcome these problems, a simple reproducible method has been improved by the use of filter papers. Whole blood obtained by venipuncture from the ear vein of guinea-pig was spotted onto a filter paper. Isepamicin in the dried blood spot was extracted with 0.5 M Na2HPO4 buffer by incubation and determined by fluorescence polarization immunoassay. Linearity was established over the range of 5-150 micrograms/ml by using only 100 microliters of whole blood. Consequently its accuracy and precision were good, with mean coefficient of variation of less than 5%. The method described here correlates well with a conventional sampling method and could be used for the pre-clinical study of isepamicin blood levels of individual guinea-pigs. This method is suitable for the simultaneous measurement of aminoglycoside antibiotics or physiological parameters after the administration of aminoglycoside antibiotics for the pharmacokinetics study.

Animals↗