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Biomedical subjects

T Kawada

Publications and source records attributed to T Kawada.

At least 307 records · Page 17Linked to original sources
PubMed1985

Formation and metabolism of pungent principle of Capsicum fruits. XV. Microdetermination of capsaicin by high-performance liquid chromatography with electrochemical detection.

A new, highly sensitive method for quantitative separation and determination of capsaicin and dihydrocapsaicin by high-performance liquid chromatography with electrochemical detection is elaborated. The method employs a Cosmosil 5Ph column eluted with 100 mM potassium dihydrogenphosphate containing 45% acetonitrile (pH 5.0) at a flow-rate of 1.0 ml/min, and an electrochemical detector (at a potential of +750 mV versus the Ag/AgCl electrode). The detection limits for both capsaicin and dihydrocapsaicin were 12 pg (39 fmol) at a signal-to-noise ratio of 3:1. By applying this method, the biological half-life of capsaicin in the rat was investigated.

Animals↗
PubMed1985

[Effects of Young's solution (YNG solution) on cardiac function and mitochondrial function during one hour ischemia at 30 degrees C and after reperfusion].

In a previous paper from this laboratory, protective effects of YNG solution on the myocardial mechanical function and metabolism of the heart arrested at 10 degrees C ascribable to the presence of Mg2+ were demonstrated. In order to further clarify the role played by Mg2+ in the protection, the present experiment was conducted using the isolated perfused guinea pig heart arrested at 30 degrees C. While the time to arrest of the contraction was equally short both with YNG (K+ + Mg2+) and K (K+) solutions, the time to resumption of contraction was significantly longer with K solution than with YNG solution, and the regular contraction was not resumed with the former solution. The recovery of the coronary flow, left ventricular pressure and dp/dt after reperfusion was around 100% with YNG solution, while the recovery was significantly poorer with K solution. Although the mitochondrial function was well maintained during the arrest both with YNG and K solution, the recovery of the mitochondrial function after reperfusion was observed only with YNG solution; severe damage was noted in mitochondria of the hearts arrested with K solution. There was a good correlation between the changes in mitochondrial function and those in cardiac function.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Gastrointestinal absorption and metabolism of capsaicin and dihydrocapsaicin in rats.

Gastrointestinal absorption of capsaicin and dihydrocapsaicin was studied in rats in vivo and in situ. Rapid absorption of capsaicin or dihydrocapsaicin from stomach and small intestine occurred in vivo. About 85% of the dose was absorbed in the gastrointestinal tract within 3 hr. In situ, within 60 min after the administration of capsaicin and dihydrocapsaicin into stomach, jejunum, and ileum, about 50, 80, and 70% of the respective dose had disappeared from the lumen. When 2,4-dinitrophenol or NaCN was added, no significant reduction in uptake of [3H]dihydrocapsaicin was observed in the jejunum. These results suggested that capsaicin and its analogs were absorbed by a nonactive process in jejunum. [3H]Dihydrocapsaicin was mainly absorbed via the portal system but not a mesenteric lymphangial one. The radioactivity in the portal blood was composed of 85% of [3H]dihydrocapsaicin and 15% of its metabolite (8-methyl nonanoic acid) bound to the albumin fraction. Dihydrocapsaicin-hydrolyzing enzyme activity was found in jejunal tissue. These results suggest that capsaicin and its analogs partly received a first-pass effect, i.e., metabolism of a compound following first absorption in the gastrointestinal tract. It is concluded that capsaicin and its analogs are readily transported to the portal vein through the gastrointestinal tract by a nonactive process and partly metabolized during absorption.

Absorption↗
PubMed1984

Heterogeneity of free valine pools for protein synthesis on free and membrane-bound polysomes in rat liver.

When rat liver was pulse-labeled with [3H]valine in vivo, the nascent peptide on membrane-bound polysomes was found to be more highly labeled than that on free polysomes. Nascent peptides were purified from both classes of polysomes and, after hydrolysis, the amino acids were reacted with 14C-labeled 1-fluoro-2,4-dinitrobenzene. The specific activity of [3H]valine was determined from the [14C]-dinitrophenyl-[3H]valine after purification by two-dimensional thin layer chromatography. With this approach we found that the specific activity of [3H]valine in the nascent peptide of membrane-bound polysomes was more than twice that of free polysomes. Moreover, when rats were pretreated with a lysosomal protease inhibitor, the differences between the specific activities of valine in nascent peptides of the two classes of polysomes tended to decrease. Our results indicate the existence of two distinct pools for valine used for protein synthesis in liver cells; one serves as a precursor for the synthesis of secretory proteins on membrane-bound polysomes and the other as a precursor for the synthesis of intracellular proteins on free polysomes.

Animals↗
PubMed1984

Functional and metabolic effects of cardioplegia induced by a young's solution (YNG solution) as assessed in isolated atrial preparations and in isolated perfused heart preparations of the guinea pig.

p6e protective effects of Young's solution (YNG solution), a cardioplegic solution, on the myocardial function and metabolism were assessed in isolated atrial preparations and isolated perfused heart preparations of the guinea pig. In atrial preparations, the time to arrest of the contraction became shorter as the concentrations of the K+, Mg++, and K+-Mg++ solutions increased, while the time to resumption of the contraction was lengthened. There was no difference in the time to arrest between K+ and K+-Mg++ solutions, but the time to resumption was reduced with K+-Mg++ solution to about half the value with K+ solution. YNG solution represented an optimum solution for obtaining a quick cardiac arrest and quick resumption of contraction. In the isolated perfused heart, the time to arrest was similar for all the cardioplegic solutions used and the heart stopped in diastole. However, the time to arrest was longer with cold Krebs-Henseleit's solution (cold cardioplegia). The time to resumption of the contraction was the shortest with YNG solution, which yielded the highest mitochondrial respiratory control ratio (RCR) and ADP/O ratio. There was a negative correlation between the time to resumption of contraction and mitochondrial RCR or ADP/O ratio (r = -0.50 and -0.58, respectively).

Animals↗
PubMed1984

Effects of cardioplegia induced by a Young's solution (YNG solution) on the blood-perfused canine papillary muscle preparation.

Experiments were carried out in the blood-perfused canine papillary muscle preparation to evaluate the protective effect of a cardioplegic solution, Young's solution (YNG solution), on the myocardial function. Both in spontaneously contracting preparations and in electrically paced (2 Hz) preparations, the time to the cardiac arrest and the time to the maximum blood flow were found to be significantly shorter when the cardiac arrest was induced with cardioplegic solutions than when it was induced with the cold modified Krebs-Ringer's solution (cold cardioplegia). The maximum blood flow of the paced preparation tended to be greater with cardioplegic solutions. The time to resumption of regular contractions was significantly shorter with YNG solution as compared with cold cardioplegia. The developed tension and the blood flow at the time of resumption of the regular contractions tended to approach the control value more quickly with YNG solution, as compared with other cardioplegic solutions and cold cardioplegia. It is concluded that YNG solution represents an optimal cardioplegic solution.

Animals↗
PubMed1984

Long-term follow-up result of portopulmonary shunt by splenopneumopexy on membranous obstruction of the inferior vena cava.

A patient with membranous obstruction of the inferior vena cava (MOVC) who underwent portopulmonary shunting by splenopneumopexy 13 years before developed hepatocellular carcinoma (HCC). Postmortem studies revealed HCC in the bilateral lobes of the liver with cirrhosis and complete MOVC. There were numerous new vessel formations in the portion of the splenopneumopexy, which proved persistence of the patency. Clinically, postshunt encephalopathy, hepatic deterioration, and cardiac-respiratory dysfunction in the long-term follow-up period were not noticed. Factors that contributed to the occurrence of HCC are also discussed.

Carcinoma, Hepatocellular↗