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T Yamahira

Publications and source records attributed to T Yamahira.

At least 19 recordsLinked to original sources
PubMed1998

The parathyroid glands of two species of dolphin--Risso's dolphin, Grampus griseus, and bottlenose dolphin, Tursiops truncatus.

Although there have been many reports regarding the structure of the parathyroid glands of various terrestrial mammals, little is known about the parathyroid glands of marine mammals including Cetacea. The morphology of the parathyroid glands of three Risso's dolphins, Grampus griseus (about 3 m in length and 300 kg in weight), and three bottlenose dolphins, Tursiops truncatus (about 3 m in length and 300 kg in weight), was examined macroscopically and microscopically. The dolphins examined in the present study had two or four parathyroid glands that varied in size and location on the thyroid gland. Each parathyroid gland was encapsulated by fibrous tissue on the dorsal surface of the thyroid gland, and was divided into several lobules by interlobular connective tissue which contained numerous capillaries. The parenchymal cells consisted of pale staining chief cells. Each cell was polygonal and about 15 microm in diameter, and had one round or oval nucleus. Oxyphil cells were not found. Considering their greater body size, the parathyroid glands were rather small. By electron microscopic observation, the parathyroid gland of the bottlenose dolphin had sparse granular endoplasmic reticulum, poorly developed Golgi complexes, and abundant secretory granules in the cytoplasm of the chief cells. These results support a possibility that the activity of the parathyroid gland is suppressed to adapt to a sea habitat.

Animals↗
PubMed1998

Development of novel chitosan derivatives as micellar carriers of taxol.

PURPOSE: To develop an intravenous injectable carrier composed of chitosan derivatives for taxol. METHODS: A chitosan with lauryl groups attached to amino groups to provide the hydrophobic moieties and, carboxymethyl groups attached to hydroxy groups to provide the hydrophilic moieties (N-lauryl-carboxymethyl-chitosan = LCC), was newly synthesized. The solubility of taxol in LCC micelles in aqueous solution was examined. The hemolysis test of LCC and the growth inhibition experiment of taxol-loading micelle using KB cells were also performed as in vitro assay. RESULTS: It was found that LCC solubilized taxol by forming micelles with particle sizes less than 100nm. This particle size was considered effective for passive targeting for tumors. The concentration of taxol in the micellar solution was very high, with a maximum of 2.37mg/mL. This maximum was 1000 times above that in a saturated solution of taxol at pH 7.4. Hemolysis testing as an in vitro assay indicated that LCC was safer than Polysorbate 80 (TO-10M) as intravenous surfactant in terms of induction of membrane damage. As judged by cytostatic activity against KB cells, taxol retained activity even when included in LCC micelles. LCC-entrapped taxol was more effective in cytostatic activity than free taxol in low concentrations. CONCLUSIONS: The results of solubilization capacity examination, hemolysis testing, and cytostatic activity suggest that LCC may be useful as a carrier of taxol.

Animals↗
PubMed1998

Ultrastructure of the parathyroid gland of the young golden hamster after short-term treatment with ethanol.

We studied the ultrastructure of the parathyroid gland of young golden hamsters after short-term treatment with ethanol (1.5 g/kg bw or 6.0 g/kg bw). We did not find any ultrastructural changes of the parathyroid gland after administration of 1.5 g/kg ethanol. In the hamsters, 3 hours after administration of 6.0 g/kg ethanol, the mean serum calcium concentration was significantly low as compared to that of the control animals. In the parathyroid gland 1 hour after administration of 6.0 g/kg ethanol, the Golgi complexes associated with a few prosecretory granules and the volume density occupied by the Golgi complexes decreased compared with that of the control animals. In the parathyroid glands 3 hours after administration of 6.0 g/kg ethanol, the Golgi complexes decreased as compared with those of the control animals, while the large vacuolar bodies increased. These findings suggest that the cellular activity of the parathyroid gland is suppressed after short-term treatment with ethanol. Intracellular lumen was found in the parathyroid chief cells 3 hours after administration of 6.0 g/kg ethanol, and the significance of this structure is discussed.

Animals↗
PubMed1998

Effect of immobilization on the ultrastructure of the golden hamster parathyroid gland.

To investigate the morphological changes of the parathyroid gland of the immobilized hamsters, we studied the ultrastructure of the parathyroid gland of golden hamsters kept in special small cage (Ballman cage II). All hamsters of the control group were kept in one ordinary cage. Each hamster of the isolated group was kept in ordinary cage individually. Each hamster of the immobilized group was kept in Ballman cage II individually. All hamsters were kept for 5 days. On the first and fifth day of the experiment, bone mineral content (BMC) and bone mineral density (BMD) of whole body were measured by dual energy X-ray absorptiometry (DXA). In the control and isolated groups, BMD of the fifth day was significantly increased as compared to that of the first day. In the immobilized group BMC and body weight were significantly decreased. There was no significant difference among 3 groups concerning the mean serum calcium level. Volume density of the cell organelles and inclusions was estimated and compared among 3 groups. Volume density of the lysosomes and large vacuolar bodies of the isolated and immobilized groups was significantly higher than that of the control group. Much more lipid droplets were observed in the immobilized group than the control and isolated groups. No particular differences were observed as to the Golgi complex in the isolated and the immobilized groups compared to the control group. These findings suggest that the cellular activity of the parathyroid gland is suppressed with immobilization.

Absorptiometry, Photon↗
PubMed1996

Ultrastructural changes in water-clear cells of the golden hamster parathyroid gland after streptozotocin treatment.

The effects of streptozotocin treatment on parathyroid water-clear cells in golden hamsters were investigated. In the cytoplasm of the water-clear cells, lipid droplets were increased as compared to that of the control animals. This finding suggests that treatment of streptozotocin affects functional activity in the parathyroid water-clear cells of the golden hamsters.

Animals↗
PubMed1995

Effects of progesterone on the ultrastructure of the golden hamster parathyroid gland.

The ultrastructure of the parathyroid glands in golden hamsters after administration of progesterone was investigated. In the parathyroid glands of the female hamsters after administration of progesterone, the mean serum calcium concentration was significantly higher when compared to that of the control hamsters. In the male experimental hamsters, the percentage area occupied by Golgi complexes and lipid droplets was significantly increased when compared to that of the control hamsters, respectively. In the female hamsters after administration of progesterone, the percentage area occupied by large vacuolar bodies was significantly decreased when compared to that of the control hamsters. In the male and female experimental hamsters, the mean number of secretory granules per 100 microns2 of cytoplasm showed a significant increase compared with that of the male and female control hamsters, respectively. These findings suggest that the secretory activity of the parathyroid glands may be stimulated in response to hypocalcemia induced by progesterone.

Animals↗
PubMed1994

Effects of prostaglandin E2 on the ultrastructure of the golden hamster parathyroid gland.

The effects of different ages on large vacuolar bodies in the parathyroid glands of golden hamsters after administration of prostaglandin E2 (PGE2) were investigated. In the parathyroid glands of the young and senile animals 15 min and the senile animals 60 min after administration of PGE2, the mean serum calcium concentration was significantly higher when compared to that of the young and senile control animals, respectively. In the experimental adult animals 60 min after administration of PGE2, the serum calcium concentration was seen to increase. In the parathyroid glands of the young animals 15 min and the adult and senile animals 60 min after administration of PGE2, the percent area occupied by large vacuolar bodies was significantly increased when 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 hypercalcemia induced by PGE2. 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↗
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↗
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

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↗