Biomedical subjects

N Fujiwara

Publications and source records attributed to N Fujiwara.

187 records · Page 11Linked to original sources

PubMedDate not supplied

Properties of intracellular calcium stores and their role in receptor-mediated catecholamine secretion in rat adrenal chromaffin cells.

Simulation of rat adrenal chromaffin cells either with receptor agonists such as muscarine, bradykinin and histamine or with caffeine in Ca(2+)-free Krebs solution induced a brief increase in the intracellular free Ca2+ concentration, [Ca2+]i, which terminated within 90 s. Both the agonist- and caffeine-induced [Ca2+]i responses were abolished in cells which had been treated with either 500 nM thapsigargin (TG) or 20 microM ryanodine, suggesting that inositol trisphosphate and caffeine cause Ca2+ release either from the same Ca2+ store or from distinct stores which exchange Ca2+ rapidly. In normal Krebs solution, these agonists evoked catecholamine (CA) secretion which showed an initial transient followed by a sustained component. Neither component of the secretion was significantly affected by TG or ryanodine. In the medium containing 16 microM Ca2+ or no Ca2+, CA secretion evoked by 30-second stimulation with 100 microM muscarine was 59 or 7%, respectively, of that evoked in the normal medium containing 2 mM Ca2+. In TG-treated cells, the CA secretion at 16 microM Ca2+ was reduced to 23% and that in the Ca(2+)-free medium was completely abolished. These results suggest that the receptor-mediated Ca2+ entry solely determines the rate of CA secretion in rat chromaffin cells when stimulated by receptor agonists in the normal medium, whereas intracellular Ca2+ release and Ca2+ entry may cooperatively support the secretion when cells are stimulated in media containing low concentrations of Ca2+.

Adrenal Medulla↗

PubMedDate not supplied

Arginine vasopressin increases perinuclear [Ca2+] in single cultured vascular smooth muscle cells of rat aorta.

The effects of arginine vasopressin (AVP, 10(-7) M) on the spatial dynamics of intracellular [Ca2+] in single cultured smooth muscle cells of the rat aorta were studied by digital imaging microscopy using the fluorescent Ca2+ indicator fura-2. The nuclear and cytosolic regions were distinguished by the fluorescent image excited at 380 nm. Changes in intracellular [Ca2+] were expressed as percent increases in the ratios of fluorescence intensity at 500 nm excited by 340 and 380 nm. AVP increased the nuclear and cytosolic [Ca2+] in Ca(2+)-containing (control) (285 +/- 27 and 172 +/- 22%, respectively) or Ca(2+)-free (203 +/- 26 and 121 +/- 15%, respectively) solutions. However, caffeine (20 mM) and ryanodine (20 microM) greatly attenuated the [Ca2+] increase induced by AVP in both regions (61 +/- 21 and 42 +/- 15%, respectively). On the ratio image, the nuclear region was discriminated from other regions at the peak response to AVP in preparations treated with caffeine and ryanodine, whereas the outline of the nuclear region was indistinct in untreated preparations. The finding implies that caffeine- and ryanodine-responsive Ca2+ storage sites may exist in the region surrounding the nucleus. The results suggest that the region surrounding the nucleus may be one of the important Ca2+ storage sites with regard to the responses of rat aortic smooth muscle cells to AVP.

Animals↗

PubMedDate not supplied

Relation between spinal cord and epidural blood flow.

To test applicability of monitoring regional spinal cord blood flow by measuring regional epidural blood flow, both were simultaneously measured by the hydrogen clearance method in response to changes in PaCO2 and mean arterial blood pressure in rats anesthetized with pentobarbital. An excellent correlation was found between regional spinal and epidural blood flow over a physiological range of PaCO2 (27.8-66.7 torr) and blood pressure (30-130 torr), while a poor correlation was demonstrated between regional spinal or epidural blood flow and regional muscle blood flow in response to these same physiological parameters. Moreover, the rates of change in regional spinal and epidural blood flows were almost the same in response to both PaCO2 and blood pressure. These results suggest that both regional spinal and epidural blood flow are regulated by a similar mechanism and suggest that regional spinal cord blood flow can be monitored by regional epidural blood flow.

Animals↗

PubMedDate not supplied

Morphological changes during survival, cellular transformation, and calcification of the embryonic mouse: Meckel's cartilage transplanted into heterotopic sites.

Meckel's cartilages obtained from 18-day-old embryonic mice were transplanted into heterotopic sites to examine their site-specific effects on cellular modification, calcification, and long-term survival. The explants were isografted into the liver, subcutaneous tissue, anterior chamber of the eye, kidney, peritoneal cavity, and intrafemoral muscle of mouse for up to 2 weeks. In addition, Meckel's cartilages were wrapped in a Nucleopore filter and transplanted into the spleen. Grafted Meckel's cartilages were observed by light and electron microscopy, including application of von Kossa's reaction and osmium-potassium ferrocyanide fixation. It was demonstrated by von Kossa's reaction that when Meckel's cartilage was grafted in liver parenchyma, initial calcification appeared on the territorial matrix as spotted deposits. The chondrocytes gradually transformed into small ovoidal cells and showed a morphology closely resembling that of osteocytes. Transplants in the kidney subcapsular site contained active surviving chondrocytes, and subcutaneously grafted Meckel's cartilage revealed three types of chondrocytes: nonhypertrophic and calcification-inducing hypertrophic chondrocytes, as well as cells showing osteocytelike phenotypes. Intraocular and Nucleopore filter-wrapped explants showed degenerative changes, and peritoneal-cavity transplants showed cellular hypertrophy, but calcified precipites were not observed. The present investigation demonstrated that in blood-rich tissues Meckel's cartilage showed long-term survival and could modulate calcified precipitation. Thus, this adaptation of Meckel's cartilage to the environment of various heterotopic sites suggests that it has the ability to induce calcification.

Animals↗

PubMedDate not supplied

Transvenous embolization of high flow carotid cavernous fistula: a case report.

We treated a patient with a high flow traumatic carotid-cavernous fistula (CCF) by embolization using detachable balloons and metallic coils, by transarterial and transvenous approaches. The patient was a 20-year-old woman who had fractures in the skull base from a traffic accident. She was admitted to our hospital one month after the accident due to exophthalmos, chemosis, and periorbital bruit. Cerebral angiograms demonstrated left traumatic CCF and steal phenomenon of blood flow. Balloon embolization by transarterial approach performed three times was unsuccessful, probably because of balloon puncture due to bone fragments. Embolization using metalic coils via the superior ophthalmic vein route was then attempted. As a result of this approach, complete obliteration of CCF was obtained, and clinical symptoms subsided within a few days. Treatment of CCF by transvenous approach is one alternative when transarterial occlusion is difficult.

Adult↗

PubMedDate not supplied

Radiologic manifestation of spinal accessory neurinoma: a case report.

Spinal accessory nerve neurinoma is very rare; only 12 cases have been reported in the literature. We describe a 54-year-old woman who had a cisterna magna tumor expanding extracranially to the C1 cervical body. The tumor originated from the spinal root of the right accessory nerve. The radiological features including CT, MRI, and angiography are discussed. There have been reports on cranial MRI studies of spinal accessory neurinoma. MRI suggested an extra-axial tumor. The histological diagnosis was mixed Antoni A and B neurinoma. The neuroradiological findings of 12 cases of neurinoma of the accessory nerve reported in the literature are reviewed.

Accessory Nerve↗

PubMedDate not supplied

Rounded atelectasis formation following decrease of pleural effusion: a case report.

We present a case of rounded atelectasis (RA) observed continuously following decrease of pleural effusion. The collapsed right lower lobe adjacent to pleural effusion changed its shape from wedge-shaped consolidation with air-bronchogram to oval and flat formation at last. The vessels and bronchi curving into RA were detected by CT and we called it horizontal comettail sign. When a mass is detected following decrease of pleural effusion and vessels and bronchi are curving into the mass, the mass may be diagnosed as RA and no further examination may be necessary.

Bronchography↗