Biomedical subjects
Publications and source records attributed to Z Tamura.
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We improved our fluorimetric analysis of adenine compounds by high performance liquid chromatography(HPLC). Bromoacetoaldehyde was better than Chloro- or iodoacetoaldehyde as the reagent of fluorescent derivatization. A moderate reaction for unstable ADP and ATP was found and their fluorescent derivatives were separated by HPLC using Hitachi gel No. 3012-N. The method was applied to determine cAMP in human urines and a catecholamine receptor system. Further, a sensitive fluorescence spectrophotometer was developed. In this micro-HPLC, several ten femtomoles of the adenine compounds were separated.
A procedure was developed for the separation and determination of dopamine-3-O-sulfate (DM-3-S) and dopamine-4-O-sulfate (DM-4-S) in the urine of subjects administered L-DOPA. The method consists of sample preparation using cation- and anion-exchange resins followed by determination of the sulfates by high-performance liquid chromatography. The addition recoveries were 96 +/- 2.9% (S.D.) for DM-3-S and 93 +/- 3.0% (S.D.) for DM-4-S. Twenty samples could be measured per day. When every 2-h urine specimen from normal subjects was analyzed after L-DOPA administration (0.5 g), the maximum excretion of each sulfate was observed in the second 2-h specimen. For the first 6 h 7.5 +/- 1.5% (S.D.) of the administered L-DOPA was excreted as DM-O-sulfates. During this time, the ratio of DM-4-S to the DM-O-sulfates was 11.7 +/- 0.58% (S.D.).
Relationships among plasma total (Ct), plasma protein unbound (Cf) and mixed salivary (Cs) concentrations of phenobarbital (PB) were studied in 29 epileptic patients. A highly significant correlation was observed between Ct and Cf. Although a significant correlation was observed between Cf and Cs, Cs/Cf ratio was only 0.63. When Cs was corrected by using pKa (7.41) and pH of saliva to estimate free PB concentration (Cest f), a highly significant correlation was obtained between Cf and Cest f, and Cest f/Cr ratio was 0.96. The temporal course of Cest f obtained from Cs after an oral single dose of 50 mg PB in a healthy adult male volunteer was approximated as a triexponential equation. The peak time was 2 hr after ingestion and apparent half life was 66 hr. The prediction of minimum concentrations at steady state on the basis of these parameters corresponded well with actually obtained Cest f following repetitive administration of PB.
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Dopamine (DM) and norepinephrine (NE) with 3,4-dihydroxybenzylamine as internal standard in normal human urine were extracted with alumina, labeled with fluorescamine and determined fluorometrically by liquid chromatography. The method is simple and in the case of excretion of DM in urines of subjects receiving 1-dopa, even the alumina treatment was unnecessary. The C.V. of method was 4.3% and 4.5% for DM and NE, respectively. The mean contents of DM and NE in 7 normal urines were 182 and 35.5 ng/mg creatinine, respectively.
Vanilmandelic, homovanillic and isohomovanillic acids in body fluids were efficiently isolated by liquid chromatography on an Amberlite XAD-4 column and by organic extraction in a special apparatus. The purified metabolites were converted into their trifluoroacetylhexafluroisopropanol esters and analyzed by mass fragmentography. The working curves of the metabolites were linear from 0.5 to 5 ng injected. The minimum detectable concentrations of all the metabolites were 2 ng/ml for plasma and cerebrospinal fluid, and 120 ng/ml for urine. The metabolite concentrations in plasma, cerebrospinal fluid and urine of normal persons and patients were determined.
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The interactions between Bifidobacterium bifidum N4 (B. bifidum) and Escherichia coli K-12 (E. coli) were investigated in their mixed cultures. Under conditions in which both bacteria grew well in their pure culture, B. bifidum inhibited the growth of E. coli even when the latter was inoculated at 10(4)-fold and preincubated for 41 hr. The inhibition in the mixed cultures appeared when the pH values were reduced below 4.6. When the lowering of pH was prevented by the addition of NaOH, no inhibition was observed. At the same initial pH of 6.5, lactic acid and acetic acid, metabolites of B. bifidum, had more inhibitory effect on the growth of E. coli than other aliphatic fatty acids. On the other hand, in the mixed cultures with E. coli, B. bifidum grew in the absence of its essential vitamins, riboflavin and pantetheine and, furthermore, aerobically.