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Biomedical subjects

N Yanagihara

Publications and source records attributed to N Yanagihara.

At least 181 records · Page 10Linked to original sources
PubMed1987

Tyrosine hydroxylase is activated and phosphorylated on different sites in rat pheochromocytoma PC12 cells treated with phorbol ester and forskolin.

Incubation of rat pheochromocytoma PC12 cells with 4 beta-phorbol-12 beta-myristate-13 alpha-acetate (PMA), an activator of Ca2+/phospholipid-dependent protein kinase (protein kinase C), or forskolin, an activator of adenylate cyclase, is associated with increased activity and enhanced phosphorylation of tyrosine hydroxylase. Neither the activation nor increased phosphorylation of tyrosine hydroxylase produced by PMA is dependent on extracellular Ca2+. Both activation and phosphorylation of the enzyme by PMA are inhibited by pretreatment of the cells with trifluoperazine (TFP). Treatment of PC12 cells with 1-oleoyl-2-acetylglycerol also leads to increases in the phosphorylation and enzymatic activity of tyrosine hydroxylase; 1,2-diolein and 1,3-diolein are ineffective. The effects of forskolin on the activation and phosphorylation of the enzyme are independent of Ca2+ and are not inhibited by TFP. Forskolin elicits an increase in cyclic AMP levels in PC12 cells. The increases in both cyclic AMP content and the enzymatic activity and phosphorylation of tyrosine hydroxylase following exposure of PC12 cells to different concentrations of forskolin are closely correlated. In contrast, cyclic AMP levels do not increase in cells treated with PMA. Tryptic digestion of the phosphorylated enzyme isolated from untreated cells yields four phosphopeptides separable by HPLC. Incubation of the cells in the presence of the Ca2+ ionophore ionomycin increases the phosphorylation of three of these tryptic peptides. However, in cells treated with either PMA or forskolin, there is an increase in the phosphorylation of only one of these peptides derived from tyrosine hydroxylase. The peptide phosphorylated in PMA-treated cells is different from that phosphorylated in forskolin-treated cells. The latter peptide is identical to the peptide phosphorylated in dibutyryl cyclic AMP-treated cells. These results indicate that tyrosine hydroxylase is activated and phosphorylated on different sites in PC12 cells exposed to PMA and forskolin and that phosphorylation of either of these sites is associated with activation of tyrosine hydroxylase. The results further suggest that cyclic AMP-dependent and Ca2+/phospholipid-dependent protein kinases may play a role in the regulation of tyrosine hydroxylase in PC12 cells.

Adrenal Gland Neoplasms↗
PubMed1987

The partially implantable middle ear implant, case reports.

The partially implantable middle ear implant (MEI) is clinically useful for bilateral deafness when it is applied to the mixed deafness with a bone conduction threshold of 20-40 dB. Two out of five successful cases are reported. It should be noted that 1.5 years have passed without changes for the first successful implantation. The next step for application of the MEI to more cases is discussed.

Adolescent↗
PubMed1987

Implantable hearing aid using an ossicular vibrator composed of a piezoelectric ceramic bimorph: application to four patients.

Direct driving of the stapes by an ossicular vibrator composed of a piezoelectric ceramic bimorph is the key functional mechanism of the partially implantable hearing aid reported in this article. Acoustic signals from a microphone are transmitted to the vibrator by means of electromagnetic induction. The devices were implanted into four patients with mixed deafness due to chronic otitis media. In the first patient, the device has continued to function for two years. The highly efficient sound transmission achieved by the direct driving of the stapes produced excellent sound perception. The functional principle, surgical procedure, and indications for this new device for hearing rehabilitation are described together with the clinical results obtained in the four patients.

Audiometry↗
PubMed1987

Pneumolabyrinth in perilymphatic fistula: report of three cases.

In three patients with perilymphatic fistula, exploratory tympanotomy revealed air bubbles emerging through the ruptured round window membrane. Review of the literature disclosed three case reports in which air was demonstrated in the labyrinth in association with perilymphatic fistula. Experimental evidence that air could enter the labyrinth through a defect of the round window membrane was described in two articles. In our patients, the perilymphatic fistula was produced by implosive force. When a perilymphatic fistula was produced by implosive force, or in the case of a pre-existing perilymphatic fistula, we assume, air may enter the scala tympani through the defect of the round window membrane if the middle ear pressure rises beyond a certain limit. Sudden onset of deafness and reversibility of hearing in perilymphatic fistula could be attributable to the presence of air bubble in the scala tympani--pneumolabyrinth--which might disturb propagation of the traveling wave of the basilar membrane.

Adolescent↗
PubMed1986

Monensin-induced influx of 22Na and the release of catecholamines in cultured bovine adrenal medulla cells and isolated chromaffin granules.

In cultured bovine adrenal medulla cells, monensin caused the release of catecholamines simultaneous with the influx of 22Na to the cells. The release of catecholamines by monensin was dependent on Na but not on Ca in the medium. Release of catecholamines and the influx of 22Na caused by monensin were not inhibited by tetrodotoxin. Monensin did not cause the release of dopamine beta-hydroxylase from the cells showing that monensin caused the release of catecholamines by a nonexocytotic mechanism. Similarly, in isolated chromaffin granules, monensin caused Na-dependent release of catecholamines, simultaneously with the influx of 22Na to the granules. Basing on these findings, monensin seems to cause a nonexocytotic release of catecholamines by acting as an Na ionophore both at cell membranes and chromaffin granule.

Adrenal Medulla↗
PubMed1986

Barium-evoked release of catecholamines from digitonin-permeabilized adrenal medullary cells.

We investigated the release of catecholamines by barium (Ba) in digitonin-permeabilized bovine adrenal medullary cells, to find out whether Ba acts directly or through the mobilization of endogenous calcium (Ca). We also tried to ascertain whether the release of catecholamines from the permeabilized cells occurs in the same manner as from the non-permeabilized control cells. In the permeabilized cells, a rise in either free Ca or Ba caused a saturable release of catecholamines. The maximal release of catecholamines caused by Ba was greater than that caused by Ca, suggesting that Ba directly triggered the release process. Release of catecholamines by Ba was accompanied by the release of dopamine beta-hydroxylase, both in the permeabilized and control cells, showing that Ba causes an exocytotic release of catecholamines. The concentration of Ba which was required for the release of catecholamines in the permeabilized cells agreed with that required in control cells. We conclude that Ba can substitute Ca in triggering the exocytotic release of catecholamines from the adrenal medullary cells. Permeabilized cells provide accurate information on the direct action of Ba in these cells.

Adrenal Medulla↗
PubMed1986

Lysis of chromaffin granules by phospholipase A2-treated plasma membranes. A cell-free model for exocytosis in adrenal medulla.

The possible involvement of phospholipase A2 (PLA2) in the release of catecholamines was examined in a cell-free model system, using isolated chromaffin granules and plasma membranes of adrenal medulla cells. Plasma membranes treated with PLA2 in the presence of Ca2+ caused lysis of chromaffin granules which was also dependent on Ca2+. This finding suggests that Ca2+ acts in two steps of exocytosis, namely in the transformation of plasma membranes into a lytic form by PLA2 and in the interaction of chromaffin granules with plasma membranes. These findings show good agreement with recently reported findings in leaky adrenal medulla cells, and suggest the involvement of PLA2 in the release of catecholamines.

Adrenal Medulla↗
PubMed1986

Inhibition of Na+-pump enhances carbachol-induced influx of 45Ca2+ and secretion of catecholamines by elevation of cellular accumulation of 22Na+ in cultured bovine adrenal medullary cells.

In bovine adrenal medullary cells, we reported that 22Na+ influx via nicotinic receptor-associated Na+ channels is involved in 45Ca2+ influx, a requisite for initiating the secretion of catecholamines (Wada et al. 1984, 1985 b). In the present study, we investigated whether the inhibition of Na+-pump modulates carbachol-induced 22Na+ influx, 45Ca2+ influx and catecholamine secretion in cultured bovine adrenal medullary cells. We also measured 86Rb+ uptake by the cells to estimate the activity of Na+,K+-ATPase. Ouabain and extracellular K+ deprivation remarkably potentiated carbachol-induced 22Na+ influx, 45Ca2+ influx and catecholamine secretion; this potentiation of carbachol-induced 45Ca2+ influx and catecholamine secretion was not observed in Na+ free medium. Carbachol increased the uptake of 86Rb+; this increase was inhibited by hexamethonium and d-tubocurarine. In Na+ free medium, carbachol failed to increase 86Rb+ uptake. Ouabain inhibited carbachol-induced 86Rb+ uptake in a concentration-dependent manner, as it increased the accumulation of cellular 22Na+. These results suggest that Na+ influx via nicotinic receptor-associated Na+ channels increases the activity of Na+,K+-ATPase and the inhibition of Na+,K+-ATPase augmented carbachol-induced Ca2+ influx and catecholamine secretion by potentiating cellular accumulation of Na+. It seems that nicotinic receptor-associated Na+ channels and Na+,K+-ATPase, both modulate the influx of Ca2+ and secretion of catecholamines by accommodating cellular concentration of Na+.

Adrenal Medulla↗
PubMed1986

Enhanced phosphorylation of tyrosine hydroxylase at more than one site is induced by 56 mM K+ in rat pheochromocytoma PC12 cells in culture.

Incubation of rat pheochromocytoma PC12 cells with dibutyryl cyclic AMP or 56 mM K+ is associated with increased activity and enhanced phosphorylation of tyrosine hydroxylase in situ. Following incubation of the PC12 cells with 32Pi, rapid isolation of the tyrosine hydroxylase, and tryptic digestion of the enzyme, two distinct 32P-peptides can be identified after paper electrophoresis. 56 mM K+ increases 32Pi incorporation into both of these peptides, whereas dibutyryl cyclic AMP increases 32Pi incorporation into only one of these peptides. The rate of increase in the incorporation of 32Pi into these two peptides in cells treated with 56 mM K+ is similar. The phosphorylation of tyrosine hydroxylase in PC12 cells occurs exclusively on serine residues. These results suggest that tyrosine hydroxylase in PC12 cells is phosphorylated on serine residues at two or more distinct sites after 56 mM K+ -induced depolarization. Since only one of these sites is phosphorylated by cyclic AMP-dependent protein kinase, activation of tyrosine hydroxylase by 56 mM K+ may involve phosphorylation by multiple protein kinases in rat pheochromocytoma PC12 cells.

Adrenal Gland Neoplasms↗
PubMed1986

Phosphorylation of tyrosine hydroxylase on at least three sites in rat pheochromocytoma PC12 cells treated with 56 mM K+: determination of the sites on tyrosine hydroxylase phosphorylated by cyclic AMP-dependent and calcium/calmodulin-dependent protein kinases.

Incubation of rat pheochromocytoma PC12 cells with the calcium ionophore, A23187 (10(-5) M), 56 mM K+, or dibutyryl cAMP (2 mM) is associated with increased activity and enhanced phosphorylation of tyrosine hydroxylase in the cells. Both the activation and the increased phosphorylation of tyrosine hydroxylase produced by A23187 and 56 mM K+ are dependent on the presence of extracellular calcium, whereas similar effects produced by dibutyryl cAMP are independent of calcium. The effects of 56 mM K+ plus dibutyryl cAMP or A23187 plus dibutyryl cAMP on the activation and phosphorylation of tyrosine hydroxylase are additive. In contrast, the effects of 56 mM K+ plus A23187 on either the activation or the phosphorylation of the enzyme are not additive. Following stimulation of intact PC12 cells with 32Pi, in order to label ATP stores, and tryptic digestion of the phosphorylated enzyme, separation of the tryptic phosphopeptides by high pressure liquid chromatography yields four distinct 32P-peptide peaks. Incubation of the cells in the presence of either 56 mM K+ or A23187 is associated with increased 32Pi incorporation into three peptides whereas, in the presence of dibutyryl cAMP, increased 32Pi incorporation is observed in only one of these peptides. When tyrosine hydroxylase purified from rat pheochromocytoma tumor is incubated in vitro with [gamma-32P]ATP and either cAMP-dependent or calcium/calmodulin-dependent protein kinase under appropriate conditions, increased phosphorylation of tyrosine hydroxylase is observed. However, even though in vitro phosphorylation by cAMP-dependent protein kinase is associated with activation of tyrosine hydroxylase, in vitro phosphorylation by calcium/calmodulin-dependent protein kinase does not lead to activation of the enzyme. Tryptic digestion of tyrosine hydroxylase phosphorylated by calcium/calmodulin-dependent protein kinase yields three distinct 32P-peptide peaks, which are identical to those phosphorylated by treatment of intact PC12 cells with either high K+ or A23187. In contrast, cAMP-dependent protein kinase phosphorylates only one peptide, which is identical to that phosphorylated by treatment of the intact cells with dibutyryl cAMP. These results indicate that tyrosine hydroxylase is activated and phosphorylated at multiple sites in PC12 cells exposed to 56 mM K+ or A23187. The results suggests that the in situ phosphorylation of these sites is catalyzed by calcium/calmodulin-dependent protein kinase; however, phosphorylation by this protein kinase is not sufficient to activate the enzyme.

Adrenal Gland Neoplasms↗
PubMed1986

Role of air bubbles in the perilymph as a cause of sudden deafness.

In the course of exploratory tympanotomies we have several times come across air bubbles leaking with perilymph. The fact prompted the hypothesis that in some cases of perilymphatic fistulas, air bubbles could enter the perilymphatic space from the fistula of the inner ear membrane and cause acute, reversible, profound sensory hearing loss. The experimental study described here was designed to test this hypothesis on guinea pigs. Experiments showed that sudden elevation of middle ear pressure by artificial means caused air bubbles to appear in the scala tympani even at a pressure level of 400 mm H2O. It also proved that air bubbles entered the perilymphatic space through the ruptured round window membrane without damaging Corti's organ or the membranous structure of the cochlea. Sequential recording of the action potential revealed that air bubbles induced acute, reversible, and profound hearing loss of cochlear origin, probably by disturbing the propagation of traveling waves of the perilymph.

Animals↗
PubMed1985

Modulation by ouabain and diphenylhydantoin of veratridine-induced 22Na influx and its relation to 45Ca influx and the secretion of catecholamines in cultured bovine adrenal medullary cells.

The effects of ouabain and diphenylhydantoin on the secretion of catecholamines induced by veratridine were investigated in cultured bovine adrenal medullary cells with special reference to ion fluxes. Veratridine itself induced an influx of 22Na and 45Ca as well as secretion of catecholamines, which were antagonized by tetrodotoxin, a selective inhibitor of voltage dependent Na channels. The secretion of catecholamines caused by veratridine was not observed either in Na free or Ca free medium. Veratridine-induced influx of 45Ca did not occur in Na free medium, while veratridine-induced influx of 22Na occurred even in Ca free medium. Veratridine-induced influx of 22Na, 45Ca and secretion of catecholamines were all potentiated by ouabain, a potent inhibitor of Na,K-ATPase. Omission of K from the medium, a condition which suppresses the Na,K-ATPase activity, also augmented these cell responses caused by veratridine. On the contrary, diphenylhydantoin, which is known to decrease the intracellular concentration of Na, reduced the veratridine-induced influx of 22Na, 45Ca and secretion of catecholamines. The potentiating effects of ouabain on the veratridine-induced cell responses were all abolished by diphenylhydantoin. These findings imply that veratridine, ouabain and K removal as well as diphenylhydantoin modulate the intracellular accumulation of 22Na which is involved in the influx of 45Ca and the secretion of catecholamines.

Adrenal Medulla↗
PubMed1985

Influx of 22Na through acetylcholine receptor-associated Na channels: relationship between 22Na influx, 45Ca influx and secretion of catecholamines in cultured bovine adrenal medulla cells.

The effects of carbachol, veratridine and high K on the influx of 22Na were investigated in relation to the influx of 45Ca and the secretion of catecholamines in cultured bovine adrenal medulla cells, in which stimulation of nicotinic but not muscarinic acetylcholine receptor causes the secretory response. (1) Carbachol caused a rapid influx of 22Na, influx of 45Ca and secretion of catecholamines, all of which occurred within 1 min and leveled off thereafter. Influx of 45Ca and secretion of catecholamines caused by carbachol were not inhibited by tetrodotoxin, but were greatly reduced in Na-free medium. Nicotine evoked an influx of 22Na and it was antagonized by hexamethonium and d-tubocurarine but not by tetrodotoxin. Muscarine had no effect on 22Na influx. The concentration-response curve of carbachol for 22Na influx was quite similar to that for 45Ca influx. (2) Veratridine induced a sustained influx of 22Na, influx of 45Ca and secretion of catecholamines, all of which were antagonized by tetrodotoxin. Influx of 45Ca and secretion of catecholamines due to veratridine were not observed in Na-free medium. (3) High K caused an influx of 45Ca and secretion of catecholamines but did not cause an influx of 22Na. High K-induced influx of 45Ca and secretion of catecholamines were not inhibited by tetrodotoxin nor by Na removal. (4) Magnesium, an inhibitor of voltage-dependent Ca channels, inhibited the influx of 45Ca and secretion of catecholamines caused by carbachol, veratridine and high K. These results indicate that cultured bovine adrenal medulla cells have at least three distinct ion channels: (1) nicotinic acetylcholine receptor-associated Na channels which are not inhibited by tetrodotoxin, (2) voltage-dependent Na channels which are kept activated by veratridine and inhibited by tetrodotoxin and (3) voltage-dependent Ca channels. Influx of Ca through voltage-dependent Ca channels is the common ionic event for the secretion of catecholamines caused by either carbachol, veratridine or high K. It seems that the influx of Na through acetylcholine receptor-associated Na channels as well as voltage-dependent Na channels, activates voltage-dependent Ca channels which triggers the secretion of catecholamines.

Adrenal Medulla↗
PubMed1985

Reconstruction of the carotid artery in radical neck dissection.

No permanent cure of head-and-neck cancer can be expected when the cancer infiltrates into the wall of the carotid artery. When the carotid artery was resected, the resultant hemiplegia poses very difficult postoperative rehabilitation problems, even though the cancer is eradicated. The recent development of vascular surgery has made reconstruction of the carotid artery feasible. In this paper, the authors reported the indications of reconstruction of the carotid artery in radical neck dissections and the surgical procedures. The indication of reconstruction of the carotid artery is determined by using of angiography, CT-scan and echography. Especially, echography is useful for determining the possibility of reconstructing the carotid artery. In the case of the infiltration type, we can start to remove tumor after preparing for the reconstruction of the carotid artery. The principle of surgical procedures consists of by-pass shunt with a vascular graft between the common and internal carotid arteries, excision of the artery with tumor and insertion of a vascular graft with end-to-end anatomoses. Concerning the selection of a vascular graft, an auto-vein graft is preferable to a synthetic graft in consideration of the postoperative patency of the vascular flow. Moreover, in the case of reconstructing the artery, preoperative irradiation has often been applied and a wide removal of the soft tissue is required, so it is recommended that the myocutaneous flap be used to cover the reconstructed area.

Blood Vessel Prosthesis↗
PubMed1985

Limitation of long term ventilation tube: in view of complications and hearing restoration.

The silicon-rubber T-tube was applied to 181 ears in 116 patients with chronic otitis media with effusion within last 5 years. Among the 181 ears, 81 (46%) accepted the T-tube without problems. In the remaining 97 ears, complications such as otorrhea, occlusion of the tube, extrusion of the tube, enlarged perforation and cholesteatoma occurred. However, in 161 ears (89%), the tube could be stabilized in the middle ear and functioned as ventilating tube beyond 3 months. Based on the incidence and prognosis of the ears with the complications and the results of hearing, we conclude that insertion of the T-tube is valuable and reliable method of treatment in the ears with retractions or atelectasis but in the ears with adhesion or granulation, this method of treatment has only limited value.

Adolescent↗
PubMed1985

Nonchromaffin paraganglioma in the nose and paranasal sinuses.

Nonchromaffin paraganglioma occurring in the nose and paranasal sinuses are extremely rare. The authors have experienced a case of nonchromaffin paraganglioma of nasal cavity which extended to the epipharynx. To our knowledge, this reported case is the fourth case that has appeared in the world literature. The patient, a 31-year-old female, had complained of a right nasal obstruction and mucopurulent rhinorrhea for two years. The right nasal cavity was filled with a polypoid mass showing no bleeding tendency or necrosis. Radiographs revealed a homogeneous shadow which occupied the entire nasal cavity and paranasal sinuses. Histopathological studies revealed that the tumor showed typical findings of nonchromaffin paraganglioma and neurosecretory granules in cytoplasm were observed by electron microscopic study. Subsequently, the tumor recurred at on the posterior epipharyngeal wall after a duration of one year and three months, and was removed completely. Since then, there was no recurrence of the tumor until the present time.

Adult↗
PubMed1985

Sino-orbital aspergillosis associated with total ophthalmoplegia.

Invasive aspergillosis of the paranasal sinuses involving the orbit is termed sino-orbital aspergillosis. Prognosis of sino-orbital aspergillosis, complicated by impaired visual acuity and neurological signs, is disastrous and usually fatal. We herein report two patients with sino-orbital aspergillosis associated with total ophthalmoplegia. One patient was successfully treated with surgical eradication including orbital exenteration. In contrast, the other died of cerebral infarction, probably due to fungal thrombosis of the middle cerebral artery, despite repeated local debridement followed by orbital exenteration and administration of antifungal agents. Experience with these cases strongly indicates the necessity of prompt surgical eradication, including orbital exenteration if necessary, in the treatment of sino-orbital aspergillosis.

Antifungal Agents↗