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Biomedical subjects

Y Toda

Publications and source records attributed to Y Toda.

At least 127 records · Page 7Linked to original sources
PubMed1985

Ultrastructural visualization of elastic fibres with a tannate--metal salt method.

A modification of the tannic acid-metal salt method was applied as an ultrastructural stain for elastin. Thin sections of glutaraldehyde-fixed, embedded rat aorta and rabbit elastic cartilage, with and without osmication, were examined. Raising the pH of the tannic acid solution from 2.7 to 9.0 progressively increased the electron-density of elastic fibres and collagen fibrils in osmicated and unosmicated specimens. The maximum tannic acid staining of elastic fibres was observed in the pH range 7.0-9.0. Collagen staining, although less intense than that of elastic fibres, was also greatest in this pH range. Elastic fibres in osmicated specimens demonstrated the strongest tannic acid staining with a minimal increase in density of collagen and cell nuclei when compared to the unosmicated specimens. Sequential treatments of osmicated specimens with tannic acid pH 7.0-9.0, and uranyl acetate, pH 4.1, enhanced the density of the elastin intensely, increased collagen staining moderately, but hardly increased the density of nuclei and microfibrils. In elastase-digested osmicated specimens, all tannic acid (pH 7.0)-uranyl acetate-reactive elastin was selectively removed. These results demonstrate that all the neutral and alkaline tannic acid-uranyl acetate methods can be used as a postembedment stain for elastin specimens fixed in glutaraldehyde and osmium tetroxide.

Animals↗
PubMed1985

Angiotoxicity in swine of a moderate excess of dietary vitamin D3.

The effects of five different dietary levels of vitamin D3 on the coronary arteries of groups of 17-60 2-month old weanling Yorkshire swine were studied. Four groups were fed the following levels of vitamin D3 per ton of ration continuously for 4 months: group I--100,000 IU, group II--300,000 IU, group IV--2,000,000, and group V--4,000,000 IU. Swine in group III were fed the diet containing 100,000 IU of vitamin D3 per ton of ration for the first 2 months of the study after which they were fed a diet supplemented with 4,000,000 IU of vitamin D3 per ton of ration for the remaining 2 months of the study. The highest degree of intimal thickening of the coronary arteries was observed among group V. The thickened areas contained numerous lipid-containing cells and degenerate cells without stainable lipid. Electron microscopic examination revealed a greater frequency of degenerate cells without stainable lipid in the coronary arteries of groups III and IV than in groups I and II. These results suggest a possible link between excessive daily intake of vitamin D3 and the development of human coronary atherosclerosis.

Animals↗
PubMed1985

Coronary arterial lesions in piglets from sows fed moderate excesses of vitamin D.

Ultrastructural studies were conducted on the coronary arteries of 6 week-old piglets from sows which received diets containing either 25 micrograms or 3.7 micrograms of vitamin D3 per pound of basal ration. The subendothelial space which was rich in mucopolysaccharide and newly formed tiny elastic fibers, contained numerous macrophages, some of which possessed lipid droplets. Degenerated smooth muscle cells with pyknotic nuclei or vesiculated organelles, and mitotic smooth muscle cells were occasionally seen in the coronary artery. Piglets from sows which were fed high doses of vitamin D had more degenerated smooth muscle cells without stainable lipid and lipid containing cells in their coronary arteries than piglets from sows which were fed low doses of vitamin D. These results suggested that an excess dietary intake of vitamin D by pregnant animals may have potential angiotoxic effects on the coronary arteries of their offsprings.

Animals↗
PubMed1985

Comparative study of the atherogenecity of dietary trans, saturated and unsaturated fatty acids on swine coronary arteries.

Three groups of two-month-old swine were fed on basal diets supplemented with either oleic acid-rich safflower oil, lard or hydrogenated soybean oil in order to monitor the atherogenecity of various dietary fatty acids. The level of plasma triglyceride was highest in the safflower oil group and the level of plasma cholesterol was highest in the lard group. The degree of intimal thickening of the coronary arteries was most severe in the safflower oil group and lease severe in the hydrogenated fat group. Both the lard- and safflower oil-supplemented groups displayed lipid-rich coronary arterial lesions. The thickened intima of these two groups contained numerous activated smooth muscle cells, degenerated cells with or without stainable lipid and abundant cell debris. Cellular changes were less conspicuous in the coronary arteries from the hydrogenated fat group than in those from the other two groups.

Adipose Tissue↗
PubMed1985

Cell fusion between L-forms and protoplasts of Staphylococcus aureus.

Mixtures of various combinations of Lysostaphin protoplasts and stable L-forms of Staphylococcus aureus, which have different markers for drug resistance, were treated with polyethylene glycol (PEG) to examine the development of doubly resistant fusion products (fusants). To recover doubly resistant colonies as L-forms, they were incubated in 4.5% NaCl-brain heart infusion (BHI) broth containing penicillin G (PCG) for enrichment culture and cultured in PCG-4.5% NaCl-BHI agar medium (method 1), while to recover doubly resistant fusants as L-forms and coccal forms, they were grown on reversion medium (R medium) which causes reversion of protoplasts or fusants to parent type cells, and then cultured on assay media, i.e., R medium, BHI agar medium or PCG-4.5% NaCl-BHI agar medium (method 2). Under both experimental conditions, doubly resistant fusants developed as L-form cells by PEG treatment of pairs of protoplasts carrying the chloramphenicol (CP)-resistance plasmid and L-forms having chromosomal resistance to streptomycin (SM). In the reverse combinations, i.e., protoplasts showing chromosomal SM-resistance and L-form cells carrying the CP-resistance plasmid, the first method gave no doubly resistant colonies. By the second method, without enrichment culture on R medium, the latter combination gave doubly resistant fusants as L-form, coccal-type and mixed-type colonial forms, while when the PEG-treated mixture was enriched on R medium, fusants were obtained exclusively as the coccal type on either R medium or BHI agar assay medium. Neither of the methods yielded colonies of doubly resistant fusants on PEG-treatment of pairs of protoplasts and L-forms both of which were chromosomal, but with different drug resistances. These results show that PEG-induced cell fusion between protoplasts and L-forms of S. aureus, unlike the fusion between protoplasts or between L-forms, resulted in transfer of the drug resistance controlled by the plasmid to the fusion products. The fusants obtained were L-forms in method 1, and coccal type in the method 2.

Adhesiveness↗
PubMed1984

Prostacyclin-independence in beta-adrenoceptor mediated renin release from dog renal cortical slices.

There is some controversy regarding whether stimulation of renin release by the beta-adrenergic system is dependent on prostaglandin (PG) production. We have examined this problem in renal cortical slices of the dog and have obtained the following results: (1) Isoproterenol (4 X 10(-6) M) stimulated renin release, but had no effect on the formation of 6-keto PGF1 alpha, a stable metabolite of PGI2; (2) Indomethacin (2 X 10(-5) M) had no effect on isoproterenol stimulated renin release, but inhibited 6-keto PGF1 alpha formation; (3) Dibutyryl cyclic AMP (10(-3) M) stimulated both renin release, and 6-keto PGF1 alpha release. Indomethacin (2 X 10(-5) M) did not inhibit dibutyryl cyclic AMP-stimulated renin release, but did inhibit the production of 6 keto PGF1 alpha. These results indicate that the beta-adrenoceptor mediated renin release does not depend on the formation of PGI2, but renin release is dependent on cyclic AMP formation.

6-Ketoprostaglandin F1 alpha↗
PubMed1984

Ultrastructural cytochemistry of proteoglycans associated with calcification of shark cartilage.

Proteoglycans (PGs) as well as sulfated glycosaminoglycans (GAGs) are closely associated with cartilage calcification. An inner zone of endoskeletal tesserae of sharks is composed of a unique calcified hyaline cartilage. Initial calcification can be seen in the cartilage close to the inner zone. We have ultrastructurally examined shark, Triakis scyllia, noncalcifying, calcifying, and calcified cartilage using the tannic acid-ferric chloride (TA-Fe), the high iron diamine (HID), and the HID-thiocarbohydrazide-silver proteinate (HID-TCH-SP) methods for localization of sulfated complex carbohydrates. In noncalcifying cartilage, TA-Fe and HID strongly stained matrix granules which were round, ovoid, elongated, or irregularly shaped and presumably represented PG monomers. The size and staining intensity of the reactive matrix granules progressively decreased in calcifying cartilage toward the calcification front of the calcified cartilage. Similarly, a progressive decrease in the size of the HID-TCH-SP stain deposits in the matrix granules was observed in the calcifying cartilage close to the calcification front and was interpreted as a decrease in length of sulfate containing GAG chains. In the calcified cartilage, the highly calcified areas were often localized in the calcification front and contained few or no small HID-TCH-SP stain deposits, whereas the weakly calcified regions contained more stain deposits. These results indicate that partial and complete degradation of sulfated GAGs and/or PGs may be a requisite for calcification of shark cartilage.

Animals↗
PubMed1984

Ultrastructural changes in the comb and aorta of chicks fed excess testosterone.

The mode of cellular response to testosterone was monitored in the combs and aortas of chicks with the aid of an electron microscope. A 7-week treatment of 30 mg of testosterone per day had little effect on plasma lipid metabolism. However, this treatment resulted in the activation of fibroblasts in the comb, activation of fibroblast-like and smooth muscle cells in the aorta, and degeneration of smooth muscle cells in the aorta. A treatment of 150 mg of testosterone per day for 7 weeks induced hyperlipidemia and lipid-rich aortic lesions. The abdominal aorta had more activated and degenerated smooth muscle cells, with or without stainable lipid droplets, than the ascending aorta.

Animals↗
PubMed1984

Ultrastructural cytochemistry of oxytalan fibers in the periodontal ligament and microfibrils in the aorta with the periodic acid-thiocarbohydrazide-silver proteinate method.

Fullmer's oxytalan fibers are special connective tissue fibers in periodontal ligaments and some non-dental sites of certain animal species, and, ultrastructurally appear to resemble microfibrils related to elastogenesis. The present study has ultrastructurally examined the applicability of Thiéry's periodic acid-thiocarbohydrazide-silver proteinate (PA-TCH-SP) method for vicinal glycol-containing complex carbohydrates to the study of oxytalan fibers in rat periodontal ligaments and microfibrils of the tunica adventitia in the rat aorta, where microfibrils are often associated with amorphous elastin and are thought to be oxytalan fibers. In the periodontal ligaments, the PA-TCH-SP method weakly to moderately stained collagen fibrils, moderately stained thin fibrils composing the oxytalan fibers, and intensely stained cytoplasmic granules of fibroblasts. In the aortic adventitia, the PA-TCH-SP method moderately stained collagen fibrils. Heavier staining was observed in microfibrils, whereas the amorphous elastin lacked staining. The most intense staining was seen in cytoplasmic granules and glycogen of mural cells. These studies demonstrate that oxytalan fibers in the periodontal ligament of rats and microfibrils in the aorta of rats contain vicinal glycol-containing glycoproteins and the PA-TCH-SP method is a useful tool in ultrastructural studies of oxytalan fibers and microfibrils of rats.

Animals↗
PubMed1984

Electron microscopic comparison of the tunica media of the thoracic aorta between species.

Previous observations indicate that the tunica media of the thoracic aorta of chickens contains two populations of cells (smooth muscle cells and connective tissue cells), whereas that of the mammalian species only contains one cell type (smooth muscle cells). It was considered that this difference in chickens: a) might occur in other avian species; b) might be a common feature in other classes from phylum chordata which are inferior to mammalia; and c) might be a special adaptation for flying animals. In order to test these hypotheses, the cytology of the tunica media of thoracic aorta was studied in five mammals (human, pig, bat, rabbit, and rat), three avian species (chicken, turkey, and pigeon), one reptile (fresh water turtle), and one amphibian (frog). All animals exhibited smooth muscle cells in the tunica media of the aorta, but only the avian species demonstrated the second major cell type (interlamellar connective tissue cells). In the avian aorta the tunica media was composed of alternating layers of smooth muscle cells and fibroblast-like connective tissue cells separated by thick elastic lamellae. It is concluded that the presence of connective tissue cells in the tunica media of the aorta may be a distinctive characteristic of birds.

Animals↗
PubMed1984

Spontaneous aortic lesions in marine turtles.

Marine turtles were found to have gross aortic aneurysmal dilations and multiple, raised grayish-white plaques which resembled both the aortic lesions of Marfan's syndrome in humans and those induced by chemical manipulation in animals. Smooth muscle cells in these aortic lesions displayed considerable functional as well as morphological similarity in their response to environmental injury in both turtles and humans.

Animals↗