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Biomedical subjects

K Tsuji

Publications and source records attributed to K Tsuji.

At least 901 records · Page 50Linked to original sources
PubMed1969

Comparative study of responses to neomycins B and C by microbiological and gas-liquid chromatographic assay methods.

The relative responses of neomycins B and C have been determined by a microbiological agar-diffusion method, a turbidimetric method, and by a recently developed gas-liquid-chromatographic (GLC) method capable of separating the neomycin isomers. The ratios of response of neomycin C to neomycin B by the individual methods were as follows: agar-diffusion method, 1:3; turbidimetric method, 1:2.5; and GLC method, 1:1. When neomycin C is assumed to have 35% biological activity of neomycin B, the calculated drug contents of neomycin sulfate powders obtained by the GLC method correlated well with values obtained by the microbiological agar-diffusion assay method.

Agar↗
PubMed1967

Automated turbidimetric bioassay readout instrument using a multiple flow-cell system.

An instrument has been developed which permits the automatic quantitation of the turbidities of microbiological assay samples. Assay tubes were fed to the instrument at the end of the incubation period. The turbidity readings were automatically converted to digital data which were printed on International Business Machines (IBM) cards and from which potencies were calculated by an IBM computer. The instrument operated at a speed of over 240 tube readings per hour and was totally automatic in sample-mixing, readout, and data recording. The instrument is being used routinely at The Upjohn Co. for the turbidimetric bioassay of vitamins, with a coefficient of variation among repeated turbidity readings of 0.12 to 0.23%.

Automation↗
PubMed1967

Dose response curve linearization and computer potency calculation of turbidimetric microbiological vitamin assays.

The dose response curves of various turbidimetric microbiological assays, including vitamin B(12), Ca pantothenate, and pyridoxine (vitamin B(6)), were linear with logarithmic transformation of the responses by use of the equation derived, ln[T(x) - T(infinity)] = ln A - Bx. A Fortran computer program which used the slope ratio potency calculation was written. The assay potencies calculated by the computer program showed excellent agreement with those obtained by the manual calculation.

Biological Assay↗
PubMed1966

Liquid nitrogen preservation of Saccharomyces carlsbergensis and its use in a rapid biological assay of vitamin B6 (pyridoxine).

Growth medium as well as freezing menstruum greatly influenced the recovery of Saccharomyces carlsbergensis when it was quickly frozen in liquid nitrogen at - 196 C and quickly thawed at 40 C. Nearly 90% recovery in viability was obtained when S. carlsbergensis was grown in Trypticase Soy Broth and frozen in vitamin B(6) basal assay medium. The growth phase of S. carlsbergensis also influenced recovery after freezing. When S. carlsbergensis was grown in Trypticase Soy Broth and frozen in the broth at the logarithmic-growth phase, only 7% viability was retained; the recovery rate increased to 81% when the culture was frozen in the maximal stationary phase. To have the least possible lag period of growth after thawing, a technique called growth-phase conditioning was introduced. After 1 hr of growth-phase conditioning, S. carlsbergensis was clearly out of lag phase, and budding was observed. A vitamin B(6) microbiological assay with a 6-hr incubation period and with the use of liquid nitrogen-frozen S. carlsbergensis is described.

Biological Assay↗