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Biomedical subjects

M Taguchi

Publications and source records attributed to M Taguchi.

At least 181 records · Page 10Linked to original sources
PubMed1982

[Serum ferritin level for estimating the effect of the radiotherapy].

Serum ferritin level was evaluated as a marker for estimating the effect of the radiotherapy. The ferritin level was determined by a radioimmunoassay (SPAC ferritin kit) in sera obtained serially from 37 patients with various malignant neoplasma before and after radiotherapy. The changes in the ferritin level were investigated in comparison with various clinical findings. The decision for significant changes in the ferritin level was made by the sensitivity which is a difference value necessary to discriminate 2 values at confidence level of 95%. Out of 11 cases with clinical evidence of distant metastasis, the ferritin level was decreased in only one case (9%) and increased or unchanged in the rest. On the other hand, out of 26 cases without evidence of metastasis it was decreased in 9 cases (35%) and unchanged in 12 cases (46%). The ferritin level was either decreased (64%) or unchanged (36%) in all the 11 cases with operation prior to radiotherapy, while out of 26 cases without operation (inoperable) it was decreased in only 3 cases (12%). In all 5 cases with radiosensitive tumors as judged by tumor size the ferritin level was either decreased (40%) or unchanged (60%). Out of 28 cases with radioresistant tumors it was decreased in only 4 cases (14%). All of these results indicated that serial measurements of the ferritin level is usefull for estimating the therapeutic effectiveness in radiotherapy.

Evaluation Studies as Topic↗
PubMed1981

Regulation of Escherichia coli phosphoenolpyruvate carboxylase by multiple effectors in vivo. II. Kinetic studies with a reaction system containing physiological concentrations of ligands.

In an attempt to clarify the kinetic properties of Escherichia coli phosphoenolpyruvate (PEP) carboxylase [EC 4.1.1.31] in vivo and to evaluate the physiological significance of the individual effectors, saturation curves were obtained for each ligand with reaction mixtures (pH 7.3) containing "physiological concentrations" of the other ligands in various combinations. As the "physiological concentrations" of ligands, which are defined as the concentrations of ligands found in the glucose-grown cells, the following values were employed: PEP, 0.2 mM; acetyl-CoA(CoA-SAc), 0.4 mM; fructose 1,6-bisphosphate(Fru-1,6-P2), 2.0 mM; GTP, 1.0 mM; L-aspartate, 1.0 mM; L-malate, 1.0 mM (Morikawa, M., Izui, K., Taguchi, M., & Katsuki, H. (1980) J. Biochem. 87, 441--449). In the absence of any activator the enzyme activity was very low. CoASAc was the most powerful activator. The other two activators (Fru-1,6-P2 and GTP) exhibited essentially no activation alone, but produced a strong synergistic activation with CoASAc. The severe inhibition by L-aspartate or L-malate was effectively alleviated only through this synergistic action of the activators. The presence of all three activators decreased the half-saturation concentration (S0.5) of PEP from 15 mM to 0.35 mM and increased the maximal velocity attainable at infinite concentration of PEP about 15-fold. In the system containing all five effectors, which is close to the in vivo condition, the saturation curve of PEP was sigmoidal with a Hill coefficient of 1.6 and with an S0.5 value of 3.0 mM, which is about 15-fold larger than its "physiological concentration." On the basis of the rate-concentration curve for each effector obtained with the reaction mixture containing PEP and the other effectors at "physiological concentrations," it was suggested that all five effectors significantly contribute to the enzyme activity in vivo. Palmitoleate, another activator of the enzyme, showed no activation in such a reaction mixture. The sensitivity of the enzyme to the "physiological concentration" of each effector was also observed in an in situ system using permeabilized E. coli cells, where the enzyme concentration was as high as in vivo.

Carboxy-Lyases↗
PubMed1981

Stringent control of intermediary metabolism in Escherichia coli: pyruvate excretion by cells grown on succinate.

A large amount of pyruvate was excreted into the medium by CP78 (rel+) cells grown on succinate when they were starved for amino acids. In contrast, no such excretion was observed with CP79 (rel-) cells. This phenomenon was also seen with two other isogenic pairs of strains: NF161 (rel+) and NF162 (rel-), and 10B601 (rel+) and 10B602 (rel-). Besides succinate, L-malate, and fumarate were effective carbon sources for the excretion, but glucose, glycerol, and acetate were not. When DL-lactate was used, not only CP78 but also CP79 cells excreted pyruvate. Experiments using [1,4-14C]succinate as a carbon source revealed that pyruvate was formed by decarboxylation of one carboxyl group of succinate and that the pyruvate excretion amounted to about 40% of the total succinate degraded. Experiments designed to elucidate the mechanism of the excretion yielded the following observations. (i) The concentration of pyruvate in CP78 cells grown on the C4-dicarboxylic acids mentioned above was not significantly changed upon amino acid starvation. (ii) Guanosine 5'-diphosphate-3'-diphosphate exerted no effect on the activities of several enzymes thought to be involved in pyruvate-related metabolism. It is suggested firstly that the excretion was not due to some impairment in the biosynthetic pathway of a particular amino acid, but was due to the stringent control of central amphibolic metabolism, and secondly that no de novo protein synthesis was involved in the excretion.

Amino Acids↗
PubMed1981

Metal content of shark muscle powder biological reference material.

Powdered dried shark muscle (Cephaloscyllium umbratile) is a promising biological reference material for metal analysis. Homogeneity indices (CV%) for Na, K, Zn, As, Ca, and Hg of the shark powder were within 5%. Mercury and arsenic concentrations (total Hg, 9.1 ppm dry wt, As, 99 ppm dry wt) in shark powder are relatively high. Muscle can be obtained inexpensively, and the powder can be preserved indefinitely if kept cold.

Animals↗
PubMed1980

Regulation of Escherichia coli phosphoenolpyruvate carboxylase by multiple effectors in vivo. Estimation of the activities in the cells grown on various compounds.

Intracellular concentrations of phosphoenolpyruvate (PEP) and five kinds of allosteric effectors (acetyl-CoA, fructose 1,6-bisphosphate, GTP, L-aspartate, and L-malate) of PEP carboxylase were measured in E. coli cells grown on various compounds as a carbon source. Based on the data obtained, reaction systems which contained a definite concentration of the enzyme and the ligands at the concentrations found in vivo were constructed and the enzyme activities were measured. The ratio of each activity thus obtained to the maximal activity attainable with the same concentration of enzyme and saturating concentrations of the activators was estimated. For the cells grown on glucose, glycerol, or lactate, the extent of exhibition of the enzyme activity was 2-15% of the maximal activity. For the cells grown on acetate or oleate, the extent was 1-3%. For the cells grown on succinate, L-aspartate, L-malate, or glucose plus L-aspartate, the extent was less than 0.4%. Consideration of the data obtained in the present studies, together with those obtained in our previous studies on the enzyme level (Teraoka, H. et al. (1970) J. Biochem. 67, 567-575), showed that the control of the enzyme reaction in vivo is considerably different from that expected from the in vitro experiments, and that deficiencies of "coarse control" are covered by a "fine control."

Acetyl Coenzyme A↗
PubMed1980

Augmentation of glycogen synthesis under stringent control in Escherichia coli.

When Escherichia coli strain CP78 (rel+) was starved for isoleucine by the addition of valine, the amount of glucose in polymeric form in the cells increased markedly compared to that of the control cells. In contrast, this phenomenon was not seen in strain CP79 (rel-). The increase in CP78 was shown to be due to the increase of glycogen. These results indicate that glycogen synthesis was augmented under stringent control. This was confirmed using other isogenic pairs of rel+ and rel- strains starved for other amino acids. When the cultivation temperature of strains 10B601 (rel+) and 10B602 (rel-) possessing temperature-sensitive valyl-tRNA synthetase was shifted from 30 degrees C to 40 degrees C, no difference was observed in the response of glycogen synthesis between the two strains. These results indicate that protein synthesis was necessary for the augmentation of glycogen synthesis and that guanosine 5'-diphosphate 3'-diphosphate did not exert its effect through stimulation of the activity of pre-existing enzyme(s) involved in glycogen synthesis. These conclusions were supported by the results of experiments using chloramphenicol and rifampicin. The rates of glucose utilization of CP78 and CP79 were decreased to nearly the same extent by valine addition. This suggests that the regulation site of glycogen synthesis under stringent control resides in a step after the transport of glucose by the phosphotransferase system.

Arginine↗
PubMed1980

Augmentation of cyclopropane fatty acid synthesis under stringent control in Escherichia coli.

An abrupt increase of cyclopropane fatty acid (CFA) occurred concomitant with a decrease of the corresponding unsaturated fatty acids in CP78 (rel+) of Escherichia coli at the onset of the stationary growth phase, whereas such variations were slight in CP79 (rel-). When the cells were starved for isoleucine, the CFA content increased in CP78 but not in CP79. The rate of 14C-incorporation from [methyl-14C]methionine into CFAs increased in CP78 abut two-fold due to the starvation. The apparent level of CFA synthase also increased due to the starvation. These results that the CFA formation is augmented under stringent control.

Cell Cycle↗
PubMed1979

Rapid identification of yeasts by serological methods: a combined serological and biological method.

A total of 387 yeasts from the contents of the digestive tracts of domestic animals and poultry were identified by slide agglutination tests using factor antisera and urease tests. The results of this serological test were very satisfactory with respect to accuracy and rapidity, particularly when performed in combination with concomitant physiological tests only for assimilation of inositol and potassium nitrate. It may be concluded that such a combination of serological and biological tests is very useful for identifying yeast strains from various sources.

Agglutination Tests↗