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Biomedical subjects

R Yamazaki

Publications and source records attributed to R Yamazaki.

At least 73 records · Page 4Linked to original sources
PubMed1982

Quantitative determinations of calmodulin in the supernatant and particulate fractions of mammalian tissues.

Although calmodulin is generally regarded as a soluble protein, a considerable amount of calmodulin activity was found to be associated with particulate fractions of mammalian tissues after an extensive washing of the particulate fraction with EGTA. Identity of this particle-bound and EGTA-nonextractable form of calmodulin with soluble calmodulin was established recently (Sobue, K., Yamazaki, R., Yasuda, S., & Kakiuchi, S. (1981) FEBS Lett. 129, 215-219). The particle-associated calmodulin activity was latent to some extent and its unmasking required the presence of nonionic detergent. We have developed an assay method for the soluble and particulate forms of calmodulin in biological samples and, by means of this method, concentrations of calmodulin in rat and bovine tissues were quantitatively determined. In the supernatant, high levels (greater than 10 microM) of calmodulin were found in the testis, pituitary gland, and various areas of brain, intermediate levels (5-10 microM) in the liver, kidney, and spleen. Particulate fractions contained 10-50% of the total calmodulin contents in the tissues. Human erythrocytes contained (2.5 +/- 0.2) microM calmodulin, or (14 +/- 0.9) X 10(4) calmodulin molecules per cell.

Adult↗
PubMed1982

Pharmacological studies on Chinese cinnamon. V. Catecholamine releasing effect of cinnamaldehyde in dogs.

Effect of i.v. and i.d. cinnamaldehyde on plasma catecholamine concentration along with intestinal absorption of the drug was studied in anesthetized dogs. Cinnamaldehyde increased plasma catecholamine concentration, the effect produced through i.d. route (50-100 mg/kg) being dose-dependent and more lasting compared with that through i.v. route (20 mg/kg). In the case of 200 mg/kg of i.d. cinnamaldehyde, an exceeding increase in this parameter was obtained during the later period of time course. Intestinal absorption of cinnamaldehyde i.d. administered, which was investigated through measurement of cinnamaldehyde concentration in the portal venous blood and in blood of the postcava, occurred very early and was long-lasting. Increase in plasma catecholamine concentration produced by i.v. cinnamaldehyde disappeared after blood circulation through the adrenal glands was stopped, and was not influenced with pretreatment of hexamethonium plus atropine. Almost all the increased portion of plasma catecholamines by i.v. or i.d. cinnamaldehyde was epinephrine. It was concluded that cinnamaldehyde, entering the circulatory system, reaches the adrenals and releases catecholamines from the organ through a mechanism(s) independent of affecting the cholinergic system. i.v. DMPP which was used as a referential drug also increased plasma catecholamine concentration.

Acrolein↗
PubMed1981

Ca2+-dependent modulator proteins from Tetrahymena pyriformis, sea anemone, and scallop and guanylate cyclase activation.

Previously, the guanylate cyclase activity of Tetrahymena pyriformis was shown to be activated by an endogenous modulator (calmodulin)-like protein (Na-gao, S., Suzuki, Y., Watanabe, Y., and Nozawa, Y. (1979) Biochem. Biophys. Res. Commun. 90, 261-268). This protein has now been identified as the modulator protein. The identification was based on the capability of this protein to activate the brain modulator-deficient phosphodiesterase and the mobility of this protein upon polyacrylamide gel electrophoresis. The activation of guanylate cyclase was specifically attributable to the Tetrahymena modulator protein since other modulator proteins examined (bovine brain, sea anemone, and scallop) were ineffective. Under the conditions where the activation of Tetrahymena guanylate cyclase occurred, guanylate cyclase activities from other sources, that include rat brain, rat lung, and human platelet, were not affected. In the phosphodiesterase activation, the potencies of scallop and Tetrahymena modulator proteins, which are represented by reciprocals of the quantities of proteins required for half-maximal activation of enzyme, were 66% and 55%, respectively, of that of the brain protein. The same decreasing order was seen for the affinity of these proteins for Ca2+ in enzyme activation. The results suggest a directional change of the modulator protein during the molecular evolution toward an increase in the capability in Ca2+-dependent enzyme activation.

Animals↗
PubMed1981

Subcellular distribution of calmodulin and calmodulin-binding sites in Tetrahymena pyriformis.

The subcellular distribution of calmodulin and particulate calmodulin-binding activity was studied in a eukaryotic protozoan, Tetrahymena pyriformis NT-1. The particulate calmodulin-binding activity was found to be localized principally in microsomes and to some extent in cilia and surface membranes called pellicles. Nearly all (93%) of the total amount of calmodulin was recovered in two soluble compartments, the ciliary and postmicrosomal supernatant fractions.

Animals↗
PubMed1977

Bile acid deconjugation in intestinal obstruction studied by breath test.

Bile acid deconjugation was assessed by measuring specific activity of expired 14CO2 after the oral administration of cholyl-glycine-1-14C in 17 cases of intestinal obstruction, i.e. 15 mechanical and two paralytic. In the former, nine cases were operated and the remaining six cases were managed by the conservative treatment. Cumulative output of 14CO2 in breath for six hours before the treatment was 40.20=11.30 (mean+/-SEM) (control 2.96+/-1.16) but decreased to 6.86+/-3.64 after the treatment. Enteric bacteria capable of splitting amino moiety of the conjugated bile acid were found to be present more than 10(5)/ml. in the obstructed bowel content. Cumulative output of 14CO2 in breath for six hours in two paralytic ileus was lower than in controls. Deconjugated bile acid reported to inhibited water and electrolytes absorption in the small intestine may play an important role in fluid retention in intestinal obstruction.

Adult↗
PubMed1977

Evidence for differences in protein kinase modulator and and phosphodiesterase activator.

Both protein kinase modulator and phosphodiesterase activator activities were present in the supernatant fluid of a homogenate of bovine brain. These were separated on a DEAE-cellulose column chromatography. Separation was also achieved by an isoelectrofocusing fractionation of the supernatant fluid, isoelectric points of proteins kinase modulator and phospodiesterase activator being 4.25 and 4.44, respectively. Phospodiesterase activator was purified from bovine brain to an apparent homogenity by a procedure which did not involve a drastic treatment such as boiling. The purification of phosphodiesterase activator resulted in removing the protein kinase modulator activity and the ratio of the activity of protein kinase modulator to that of phosphodiesterase activator in the sample decreased as the purification proceeded.

3',5'-Cyclic-AMP Phosphodiesterases↗