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Biomedical subjects

S Kawada

Publications and source records attributed to S Kawada.

At least 217 records · Page 12Linked to original sources
PubMed1976

An experience in clinical application of real-time two-dimensional echocardiography.

An experience with a real-time two-dimensional echocardiographic system was presented. In this report a sagittal plane section, i.e., the section which was parallel to the long axis of the left ventricle was used. The two-dimensional section of the normal heart, mitral stenosis, interventricular septal defect (preoperatively and postoperatively), mitral prosthetic valve, pericardial effusion, and acute myocardial infarction were studied. Easy applicability, quick recording, and non-invasive nature of the procedure, make the indications widened including acutely distressed patients. We conclude that real-time two-dimensional echocardiography is one of the most promising cardiac examinations.

Adult↗
PubMed1976

Role of ascorbic acid on tyrosine hydroxylase activity in the adrenal gland of guinea pig.

The decrease of tyrosine hydroxylase activity in adrenal homogenate in scurvy was recovered after the administration of ascorbic acid. The causes of the increase in the enzyme activity after the administration of ascorbic acid have been studied. 1. No significant elevation in the enzyme activity was observed after the administration of reserpine to the scortutic guinea pig. 2. A dose of metal chelating agent, alpha, alpha'-dipyridyl, prevented the ascorbic acid-induced or reserpine-induced increase in enzyme activity in the scorbutic and the non-scorbutic guinea pigs, respectively. 3. Tyrosine hydroxylase activity was partially recovered by the administration of FeSO4 to the scorbutic guinea pig. From these results, it became clear that the induction of tyrosine hydroxylase which was not observed in scurvy was due to the deficiency of Fe2+. These results suggested that ascorbic acid affected the induction of this enzyme via Fe2+.

2,2'-Dipyridyl↗
PubMed1976

Effect of catechol-thiol conjugates on tyrosinase-dependent tyrosine hydroxylation.

1. The tyrosinase reaction in the presence of a thiol compound was studied using mushroom tyrosinase (EC 1.10.3.1) with regard to catechol-thiol conjugates. 2. Although tyrosine hydroxylation of tyrosinase was extremely decreased in the presence of a thiol compound, the inhibitory effect was removed by the addition of a pyrocatechol-cysteine conjugate, S-(2,3-dihydroxyphenyl) cysteine, which was not oxidized by the enzyme. 3. The pyrocatechol-cysteine conjugate was also able to shorten the lag period of tyrosinase-dependent tyrosine hydroxylation. 4. The sigmoidal reaction curve of tyrosine hydroxylation observed in the presence of sulfhydryl compounds was found to be caused by the catechol-thiol conjugates, the final products of the enzyme reaction, which counteract the inhibitory effect of sulfhydryl compounds. 5. The pyrocatechol-cysteine conjugate, on the other hand, was shown to cause the decrease of the reaction rate of the enzyme during incubation.

Basidiomycota↗
PubMed1975

Regulation of tyrosine hydroxylase activity by prostaglandin E1 in guinea pig adrenal gland.

The action of prostaglandin E1 on tyrosine hydroxylase activity in adrenal slices of guinea pig was studied. The activity of tyrosine hydroxylase and was decreased by the incubation of adrenal slices with prostaglandin E1 at concentrations beyond 2 mug per ml for 2 hours. The activity of tyrosine hydroxylase was stimulated by dibutyryl adenosine 3',5'-monophosphate in slices of guinea pig adrenal glands. Incubation of adrenal slices wtth the combination of PGE1 and DBc-AMP lead to a tyrosine hydroxylase activity higher than that with PGE1 alone, but not as great as DBc-AMP alone. It was suggested that PGE1 inhibited the enzyme activity independently of the cyclic AMP level. Other prostaglandins such as PGA1 and PGB1 were deficient to the extent that the tyrosine hydroxylase activity was decreased. PGE1 inhibited the enzyme activity much to the same extent seen with protein synthesis inhibitors such as cycloheximide and actinomycin D. However, PGE1 did not influence the incorporation of L-leucine-14C into acid insoluble protein. The studies reported here showed that PGE1 inhibited the synthesis of tyrosine hydroxylase.

Adrenal Glands↗