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Biomedical subjects

K Miyata

Publications and source records attributed to K Miyata.

At least 361 records · Page 20Linked to original sources
PubMed1986

Effects of sensitization of hemolytic streptococcal M-protein fraction on embryonic heart in the rat.

After sensitization by M-protein fraction (MP) of hemolytic streptococci for two generations, Wistar rats were injected with 9 ml/kg of MP on day 9 of gestation (plug day = day 0). The incidence of malformations was about 12% whether anti-MP antibody was positive or not in the maternal sera. The primary malformations were ventricular septal defect, anophthalmia, and microphthalmia. Light microscopic study revealed no myocarditis nor endocarditis in either the maternal or fetal heart. No antinuclear antibody was detected in the maternal sera by the fluorescent antibody technique. No complete heart block was found in the fetus by electrocardiogram. These results were similar to previous findings using a single injection of MP, and therefore further demonstration that the principal factor in the teratogenesis induced by MP administration in the rat is not an inflammation in the fetal organs caused by an autoimmune mechanism but rather yolk sac dysfunction.

Animals↗
PubMed1985

Uptake of released mast cell granules by reticular cells of the rat lymph node.

Granules released from mast cells were examined by electron microscopy in regional lymph nodes of rats after the injection of a large dose of horseradish peroxidase (HRP). Thirty minutes after the injection, a large number of mast-cell granules were present in sinuses, most of which adhered to the surfaces of reticular cells and some to macrophages. Two hours after the injection, a number of granules had been taken up by both reticular cells and macrophages. Reticular cells took up more granules than macrophages. Twenty-four hours after the injection, granules were scarce in both types of cells and in the extracellular space. Reticular cells surely participate in dealing with released mast-cell granules in the lymph node. Fibronectin bound to all mast-cell granules was demonstrated by immunohistochemistry. Fibronectin probably enables negatively charged mast-cell granules to approach negatively charged cell surfaces to be taken up by both reticular cells and macrophages.

Animals↗
PubMed1985

Acid-phosphatase activity of reticular cells and macrophages in the lymph node of the rat after ingestion of mast-cell granules.

Acid phosphatase (ACPase) was ultracytochemically demonstrated in the lymph-node sinus reticular cells and macrophages of rats. After the uptake of horseradish peroxidase (HRP), marked ACPase activities were seen in both reticular cells and macrophages, although only sparse ACPase activity was detected in the reticular cells of the control. After the injection of HRP into the footpad, the mast cells in the regional lymph node became degranulated, and the released granules were taken up by reticular cells and macrophages. In macrophages, these taken-up mast-cell granules exhibited ACPase reaction products, whereas none of the granules taken up by reticular cells showed ACPase activity. The heparin-protamine complex was also engulfed by reticular cells and macrophages, and ACPase activity was demonstrable in the complex taken up by both types of cell. It is probable that, as is the case in macrophages, reticular cells in the lymph-node sinuses take up and digest foreign substances through the formation of phagolysosomes, but they do not digest granules originating from the mast cells in the lymph node of the same animal.

Acid Phosphatase↗
PubMed1985

Impaired granulocyte chemotaxis and increased circulating immune complexes in Kawasaki disease.

Our study was carried out to clarify the changes in granulocyte functions and circulating immune complexes in 32 children with Kawasaki disease. Patients were divided into two groups, those with or without coronary aneurysm. In the group with coronary aneurysm, impairment of both granulocyte chemotaxis and phagocytosis was found, together with higher circulating immune complexes and normal intracellular killing activity. In the group without coronary aneurysm, impaired phagocytosis was observed, with normal granulocyte chemotaxis, circulating immune complexes, and intracellular killing activity. No correlation was observed between granulocyte chemotaxis and circulating immune complexes. Impairment of granulocyte chemotaxis and circulating immune complexes may yield pertinent information as to the degree of severity of vasculitis in Kawasaki disease.

Aneurysm↗
PubMed1985

Aldosterone antagonists. 1. Synthesis and biological activities of 11 beta,18-epoxypregnane derivatives.

Several steroid derivatives having the 11 beta,18-epoxypregnane skeleton, 7, 8, 19, 20, 21, and 31, were synthesized to evaluate their antialdosterone activity. Among them, 3-(9 alpha-fluoro-17 beta-hydroxy-3-oxoandrost-4-en-17 alpha-yl)propionic acid gamma-lactone (31) possessed fairly strong binding affinity for the cytoplasmic mineralocorticoid receptor of rat kidney and exhibited good aldosterone antagonist activity in an in vivo assay. However, its agonistic nature cannot be ignored. The properties of 31 as an aldosterone antagonist were enhanced by its very low to negligible binding affinity for the androgen, progestin, estrogen, and glucocorticoid receptors.

Animals↗
PubMed1985

Preliminary X-ray studies on Serratia protease.

Preliminary X-ray studies on Serratia protease have been carried out using crystallographic and small angle scattering techniques. The enzyme has been crystallized in three different crystalline forms by microdialysis and vapor diffusion methods using 50 mM phosphate buffer, pH 6.0, at 24 degrees C. They have orthorhombic space groups: C222(1) for one form and P2(1)2(1)2(1) for the other two forms. A small angle X-ray scattering study showed that the radius of gyration and the maximal dimension of the molecule in aqueous solution are 26.6 A and 94.5 A, respectively. The molecular weight of the enzyme was determined to be 45,000-48,000 by various physical methods.

Crystallography↗
PubMed1985

The effects of M-protein fraction of hemolytic streptococci on embryonic heart in the rat.

Wistar rats were administered M-protein fraction (MP) of group A type 12 hemolytic streptococci on day 9 of gestation. When 9 mg/kg of MP was injected, the incidence of malformations was 11.8%, and the incidence of cardiovascular malformations was 7.9%. The main malformations were ventricular septal defect, microphthalmia, and hydrocephaly. Light and electron microscopic studies revealed no myocarditis nor endocarditis in either the maternal or fetal heart. Fluorescent antibody technique demonstrated no immunological cross-reaction between MP and rat heart tissue. The results suggest that MP is slightly teratogenic in the rat.

Abnormalities, Drug-Induced↗
PubMed1985

Mast cell-Ito cell pairings found in the Disse's spaces in the liver of the beagle dog.

Ito cells (fat-storing cells), containing a few lipid droplets, appeared in the Disse's spaces of the Beagle dog liver. They ranged in diameter from 0.5 to 5 micron. The present study revealed that mast cells were also distributed in the Disse's spaces, while they were encountered only in the interlobular connective tissue in other animals. Although mast cells as well as Ito cells were distributed solitarily in the Disse's spaces, pairing of both types of cells could be frequently observed. Direct contact between both cells was verified using both light and electron microscopy. Also encountered were some peculiar figures of certain Kupffer cells engulfing the cytoplasmic processes and secretory granules of mast cells. These findings indicate a previously unknown intimate relationship between the mast cell and other perisinusoidal cells in the dog liver: the Ito cell, Kupffer cell and endothelial cell.

Animals↗
PubMed1984

Synergistic effect of subteratogenic doses of antisera on the development in the rat.

Wistar rats were administered rabbit anti-rat-umbilical-cord serum (AUCS) alone on day 9 of gestation or in combination with subteratogenic doses of rabbit anti-rat-kidney serum (AKS). The results showed that the incidence of malformation was low (13.1% +/- 7.0 S.E.) even when very high doses of AUCS alone were administered. However, the incidence markedly increased to 61.0% +/- 9.3 S.E. when a small dose (0.10 ml/100 gm) of AKS was administered on day 9 followed by 0.90 ml/100 gm of AUCS on day 10. The malformations included microphthalmia, hydrocephaly, aortic arch anomalies, ventricular septal defect, and anophthalmia, being similar to the effects of a medium dose of AKS. These results suggest that a combination of subteratogenic doses of teratogenic antisera produces malformations, possibly by mechanisms that potentiate the teratogenic action of the sera.

Abnormalities, Drug-Induced↗
PubMed1984

Intercellular junctions between macrophages in the regional lymph node of the rat after injection of large doses of steroids.

Intercellular junctions were often found between macrophages in sinuses of regional lymph nodes of the rat after injection of large doses of cholesterol, cortisone acetate, and estrone at the footpad. They were identified by subplasmalemmal densities, 20-50 nm in width, beneath the plasma membranes of apposed macrophages. No distinct filamentous structures were visible in those dense regions. Electron-dense amorphous materials are lined up at the center of the intercellular space in the junctional regions. Some macrophages form clusters with intercellular junctions. No significant difference in the effect of cholesterol, cortisone acetate, and estrone on the number of intercellular junctions between macrophages was found.

Animals↗
PubMed1984

Protection by glycerol of urinary L-alanine aminopeptidase activity from freezing and thawing inactivation.

L-Alanine aminopeptidase (AAP) and N-acetyl-beta-D-glucosaminidase (NAG) activities in urine are sensitive indicators of renal damage. However, urinary AAP loses its activity during storage in the frozen state. This study proposes a method for preventing the inactivation of AAP by adding glycerol to a final concentration of 10% to a urine sample before freezing and thawing. This study also showed that NAG is stable to freezing and thawing and is not affected by addition of glycerol.

Acetylglucosaminidase↗