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S Emura

Publications and source records attributed to S Emura.

At least 91 records · Page 5Linked to original sources
PubMed1993

Ultrastructure of the parathyroid gland of magnesium-treated golden hamster exposed to a hypergravity environment: a stereological study.

The ultrastructure of the parathyroid glands of magnesium-treated golden hamsters exposed to a 5 gravity environment was studied. In the parathyroid glands of the magnesium-treated animals exposed to a hypergravity environment, the Golgi complexes and cisternae of the granular endoplasmic reticulum were increased as compared to those of the magnesium-treated animals and decreased as compared to those of animals exposed to a hypergravity environment, but were almost the same as those of the control animals. In the control and experimental animals, the chief cells were rich in free ribosomes and mitochondria. In addition, numerous secretory granules were situated close to the plasma membrane in the magnesium-treated animals exposed to a hypergravity environment. These observations suggest that the synthesis of parathyroid hormone may be stimulated in the parathyroid glands of magnesium-treated hamsters exposed to hypergravity environment.

Animals↗
PubMed1993

[The parathyroid gland under normal and experimental conditions].

Since Sandström reported the first detailed description of the parathyroid glands of human beings in 1880, and Lever first described the ultrastructure of the parathyroid chief cells of rat in 1957, a large number of light and electron microscopic studies have been done on the parathyroid glands of numerous animal species under normal and experimental conditions. This review deals with the comparative morphology of the parathyroid glands in amphibians, reptiles, birds and mammals under normal conditions, and the problem concerning the effects of various experimental conditions on the parathyroid glands in mice, rabbits and hamsters. The parathyroid glands were recognized in all vertebrate animals higher than fish, and arose from the third and fourth branchial pouches. Several animals, such as the newt, lizard, gecko, mouse, rat, hamster and gerbil, had only two parathyroid glands, but most animals had four. In mammals, most of the parathyroid glands were closely associated with the thyroid gland, but in amphibians, reptiles and birds, the glands separated from the thyroid gland. In some mammals, the parenchymal cells of the parathyroid gland were classified under a light microscope into two main types of cells: chief cells and oxyphil cells. Examinations under an electron microscope also showed the chief cells having many cell organelles and the oxyphil cells filled with numerous mitochondria in the parathyroid glands of human beings, monkeys, cows, horses, bats and turtles. In addition, the chief cells in most animals were classified at the light microscopic level into light cells and dark cells, moreover the chief cells were also electron microscopically divided into a light and dark type showing different functional phases of a single cell type when osmium or glutaraldehyde fixative was used. However, it is widely accepted today that differences in cytoplasmic density of the chief cells are due to artifacts produced in the process of tissue preparation. The parenchymal cells of the parathyroid gland of the newt were divided into the basal cells (supporting cells) and the suprabasal cells (chief cells). In the parathyroid gland of the frog and toad, blood vessels and connective tissues were not present. In the parathyroid gland of the rabbit and hamster, the water-clear cell was observed. In the electron microscopic radioautograph of the parathyroid gland treated with 3H-leucine, most of the silver grains were seen over cisternae of the granular endoplasmic reticulum at 15 minutes, over the Golgi complexes at 30 minutes, and over secretory granules at 60 minutes.(ABSTRACT TRUNCATED AT 400 WORDS)

Aging↗
PubMed1992

Pretreatment with catalase or dimethyl sulfoxide protects alloxan-induced acute lung edema in dogs.

We tested the preventive effects of catalase, an enzymatic scavenger of hydrogen peroxide, or dimethyl sulfoxide (DMSO), a hydroxyl radical scavenger, on intravenous alloxan-induced lung edema in four groups of pentobarbital sodium-anesthetized, ventilated dogs for 3 h: saline (20 ml.kg-1.h-1) infusion alone (n = 5), alloxan (75 mg/kg) + saline infusion (n = 5), catalase (150,000 U/kg) + alloxan + saline infusion (n = 5), or DMSO (4 mg/kg) + alloxan + saline infusion (n = 5). Catalase or DMSO significantly prevented the increase in plasma thromboxane B2 and 6-keto-prostaglandin F1 alpha over 3 h after alloxan and the accumulation of extravascular lung water after 3 h [3.95 +/- 0.52 (SE) g/g with catalase, 3.06 +/- 0.42 g/g with DMSO] but not early pulmonary arterial pressor response. An electron microscopic study indicated that catalase or DMSO significantly reduced the endothelial cellular damages after alloxan. These findings strongly suggest that hydrogen peroxide and hydroxyl radical are major mediators responsible for intravenous alloxan-induced edematous lung injury in anesthetized ventilated dogs.

6-Ketoprostaglandin F1 alpha↗
PubMed1992

Effects of short-term treatment with calcium on the parathyroid glands in golden hamsters of different ages, with special reference to large vacuolar bodies.

The effects of different ages on large vacuolar bodies in the parathyroid glands of golden hamsters after short-term treatment with calcium were investigated. In the parathyroid glands of the young and adult animals 15 min and the senile animals 15 and 60 min after administration of calcium, the percent area occupied by large vacuolar bodies was significantly increased as compared to that of the young, adult and senile control animals, respectively. These findings suggest that the percent area occupied by large vacuolar bodies is increased in response to acute hypercalcemia. It is thought that in the parathyroid glands suppressed by hypercalcemia there is a relationship between the percent area occupied by large vacuolar bodies and aging.

Aging↗
PubMed1992

Stereological studies of the parathyroid gland of phosphate-treated golden hamsters subjected to a hypergravity environment.

The ultrastructure of the parathyroid glands of phosphate-treated golden hamsters exposed to a 5-G environment was studied. In the phosphate-treated animals exposed to a hypergravity environment, the Golgi complexes associated with numerous prosecretory granules, and the enlarged intercellular spaces containing floccular or finely particulate material showed a significant increase compared to those of the control, centrifuged, and phosphate-treated groups, and the cisternae of the granular endoplasmic reticulum showed a significant increase compared to those of the control and phosphate-treated groups. In addition, numerous secretory granules were situated close to the plasma membrane of chief cells in the phosphate-treated animals exposed to a hypergravity environment. These findings suggest that the synthesis, and to a greater extent the release of secretory granules may be markedly stimulated, in the parathyroid glands of phosphate-treated animals exposed to a hypergravity environment.

Animals↗
PubMed1992

Ultrastructure of the parathyroid gland of fetal and pregnant golden hamsters subjected to hypergravity environment.

The ultrastructure of the parathyroid glands of fetal and pregnant golden hamsters exposed to 5-gravity environment was studied. In the centrifuged fetal animals the Golgi complexes associated with some prosecretory granules were significantly increased compared with those of the control fetal animals, and several secretory granules were located in a peripheral position just beneath the plasma membrane. In the centrifuged pregnant animals the Golgi complexes associated with numerous prosecretory granules were significantly increased, cisternae of the granular endoplasmic reticulum appeared to be increased compared with those of the control pregnant animals, many secretory granules were located in the peripheral cytoplasm and several granules were situated close to the plasma membrane. These findings suggest that in the parathyroid glands of the fetal golden hamsters as well as the pregnant animals the synthesis and release of parathyroid hormone may be stimulated in response to a hypergravity environment.

Animals↗
PubMed1992

Effects of hypergravity environment on the parathyroid gland of the norepinephrine-treated golden hamster: a stereological study.

Effects of 5-gravity environment on the ultrastructure of the parathyroid glands of norepinephrine-treated golden hamsters were studied. In the centrifuged animals treated with norepinephrine, the volume density occupied by the Golgi complexes associated with numerous prosecretory granules was significantly increased compared with that of the control, centrifuged and norepinephrine-treated animals, as well as the volume density occupied by the cisternae of the granular endoplasmic reticulum compared with that of the control and centrifuged animals. In addition, in the centrifuged animals treated with norepinephrine, numerous secretory granules were situated close to the plasma membrane. It is suggested that the synthesis and release of secretory granules may be markedly stimulated in the parathyroid glands of the norepinephrine-treated golden hamsters subjected to a hypergravity environment.

Adrenergic alpha-Agonists↗
PubMed1992

Fine structures around the orifice of the intercostal artery of the rabbit thoracic aorta.

In hypercholesterolemic rabbits, atherosclerotic lesions easily occur in the thoracic aorta, especially at the distal and lateral sides of the walls around the orifices of the dorsal intercostal arteries. In order to examine whether some special structures that lead to atherosclerotic lesions are present even in normal conditions, the authors investigated the morphologic features around the orifice of the intercostal artery of 20 normal rabbit aortae under electron microscopy. The endothelial cells were generally fusiform but tended to be round and have a cobblestone-like appearance at the lateral side. There was intimal protrusion at the distal and lateral sides of the orifice, where the distribution and arrangement of elastic fibers and smooth muscle cells were different from those at the proximal side. At the proximal edge of the orifice, elastic fibers formed a thick plate-like internal elastic lamina beneath the endothelial cells. On the other hand, at the distal and lateral sides, elastic fibers formed close-meshed structures over the proper plate-like internal elastic lamina. These results indicate that the aortic walls at the distal and lateral sides of the orifice are structurally different from those at other regions even in normal conditions and suggest the involvement of special structures at the distal and lateral sides of the orifice in atherogenesis.

Animals↗
PubMed1992

Heterogeneity of rabbit aortic endothelial cells, with special reference to phagocytosis.

Heterogeneity of aortic endothelial cells with regard to phagocytotic ability was examined by injecting India ink into normal rabbits. Light and electron microscopic analyses revealed that particles of India ink were phagocytosed in the endothelial cells, which in turn were localized at the distal side of the orifice of aortic branches, especially those of brachiocephalic, left clavicular, and dorsal intercostal arteries. No remarkable differences were found ultrastructurally between phagocytosing and nonphagocytosing endothelial cells. Ingested India ink particles were present within phagosomes of the endothelial cells for several hours after injection; the particles eventually accumulated in the subendothelial space twenty-four hours after injection. These results indicate that an active transport system of large molecules via the phagocytotic processes is present in endothelial cells located at the distal sides of the orifice of aortic branches. These regions are known to develop initial atherosclerotic lesions in hypercholesterolemic animals. Thus, a possible correlation between phagocytotic ability of endothelial cells and development of atherosclerosis is suggested.

Animals↗
PubMed1992

Ultrastructure of the water-clear cell in the rabbit parathyroid gland.

The ultrastructure of water-clear cells has been described in human hyperplastic parathyroid glands. However, previous studies have failed to demonstrate this type of cell in normal human or other vertebrate parathyroid glands. Upon recently recognizing water-clear cells in the parathyroid glands of the golden hamster, we intended to examine the occurrence of these cells in other animals. In the present study the parathyroid glands of about one-year-old rabbits were observed by electron microscopy. Water-clear cells containing numerous vacuoles were demonstrated dispersed among the chief cells. The cells were generally situated close to the basal lamina of perivascular space which lay against the capillary vessel and were attached by desmosomes to the chief cells. Irregularly shaped vacuoles in the water-clear cells resembled dilated cisternae of the granular endoplasmic reticulum in the chief cells. Several ribosomes could be seen attached to the membrane of some of the irregularly shaped vacuoles. It is conceivable that the water-clear cells are transformed from the chief cells.

Animals↗
PubMed1992

Effects of starvation on the water-clear cell in the golden hamster parathyroid gland.

Changes of the water-clear cells of the parathyroid glands in adult and senile golden hamsters 2 and 5 days after starvation were investigated. The ultrastructure of the water-clear cells of the parathyroid glands in the starved adult and senile animals almost resembled that of the control adult and senile animals. However, lipid droplets were very numerous in the water-clear cells in the adult and senile animals after starvation. It is considered that starvation affects functional activity in the water-clear cells of the parathyroid gland.

Age Factors↗
PubMed1992

An in vitro study on the effects of melatonin on the ultrastructure of the hamster parathyroid gland.

Isolated parathyroid glands from adult female golden hamsters were incubated on a black Millipore filter in an incubation vessel containing Ham's F-12 medium, with or without melatonin at final concentration of 10(-5) M for 1 hour. In the parathyroid glands used for in vitro treatments with melatonin, the Golgi complexes associated with a few prosecretory granules and cisternae of the rough endoplasmic reticulum showed a significant decrease, and lipid droplets and lysosomes appeared to be increased compared with those of the control parathyroid glands. These changes are considered to be induced by suppression of the synthesis of parathyroid hormone in parathyroid glands incubated in a vessel containing medium with melatonin.

Animals↗
PubMed1992

[Two cases of the horseshoe kidney].

The present report is concerned with two cases of the horseshoe kidney. During the dissecting practice at Gifu University School of Medicine in 1991, the case 1 was found in a female Japanese cadaver of 84 years old and the case 2 in a female Japanese cadaver of 84 years old and the case 2 in a female Japanese cadaver of 85 years old. 1) In both cases, the two kidneys were united at their lower ends across the midline of the body. The part of fusion called the isthmus consisted of renal tissues. 2) In both the cases 1 and 2, the hilus of each kidney opened anteriorly, and the ureters passed in front of the isthmus and entered the urinary bladder normally. The location of each kidney was lower than that of the normal kidney. 3) Surplus arteries arising from the abdominal aorta were observed in the cases 1 and 2. In the case 1, one surplus artery entered the left kidney and the isthmus. In the case 2, five surplus arteries were observed; two arteries entered the right kidney, one the left kidney and two the isthmus. 4) The incidence of the horseshoe kidney during the dissecting practice at Gifu University School of Medicine from 1971 to 1991 was 0.33% (three out of 908 bodies). 5) In both the cases 1 and 2, no malformation was observed in other organs.

Aged↗
PubMed1991

Ultrastructural studies on the effects of hypergravity environment on the parathyroid glands in golden hamsters of different ages.

The ultrastructure of the parathyroid glands of infantile, young, adult and senile golden hamsters subjected to a hypergravity environment was studied. In the parathyroid glands of 5-, 10- and 20-day-old, and 1- and 3-month-old golden hamsters exposed to a hypergravity environment, the Golgi complexes were significantly increased, and in 5-, 10- and 20-day-old, and 1- and 8-month-old animals exposed to a hypergravity environment, the cisternae of the granular endoplasmic reticulum appeared to be increased as compared to those of each control group. In addition, in centrifuged animals numerous prosecretory granules were observed in the Golgi areas, and many secretory granules were located in the peripheral cytoplasm. The ultrastructure of the parathyroid glands of 14-month-old centrifuged animals resembled that of 14-month-old control animals. These results suggest that the secretory activity of the parathyroid gland may be stimulated in infantile, young and adult golden hamsters subjected to a hypergravity environment and may not be stimulated in senile animals subjected to a hypergravity environment.

Aging↗
PubMed1991

Electron-microscopic study of the parathyroid gland of epinephrine-treated golden hamsters subjected to hypergravity environment.

The ultrastructure of the parathyroid glands of golden hamsters subjected to 5-gravity environment after administration of epinephrine was studied. In the epinephrine-treated animals exposed to a hypergravity environment, the Golgi complexes associated with numerous prosecretory granules were significantly increased compared with those of the control, centrifuged and epinephrine-treated animals, as well as the cisternae of the granular endoplasmic reticulum compared with those of the control and centrifuged animals. In addition, many secretory granules were situated close to the the plasma membrane of the chief cells in the epinephrine-treated animals exposed to a hypergravity environment. Those observations suggest that the secretory activity of the parathyroid gland may be markedly stimulated in the epinephrine-treated animals exposed to a hypergravity environment.

Animals↗