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Biomedical subjects

N Yanagihara

Publications and source records attributed to N Yanagihara.

At least 163 records · Page 9Linked to original sources
PubMed1989

[Single channel cochlear implant: application to three patients].

Single channel cochlear implant of 3M/House design was implanted to the three patients with profound hearing loss. Before the implantation, use of hearing aid had not afforded serviceable hearing enough for speech recognition in these patients. Postoperative courses were uneventful. Speech rehabilitation was started at 3 weeks after the surgery. The speech tracking scores with the cochlear implant plus lipreading achieved 20-25 bunsetues (the minimum meaningful unit of the Japanese sentence) per minute at three or four months after the operation. All the patients could recognize speech of daily life with help of lipreading. However, speech recognition by the cochlear implant alone was not satisfactory.

Adult↗
PubMed1989

[Modification of speech encoding process of single channel cochlear implant utilizing digital delay circuit].

Speech perception by single channel cochlear implant can be improved to some extent by modifying the encoding process of the speech signals. The principle of our encoding strategy is to present speech signals with appropriate delay time for lower frequency components of the speech sound, while without delay for higher frequency components. This is based on a cochlear physiology that higher frequency sounds are perceived earlier than lower frequency sounds, since the former is perceived at the basal turn and the latter at the apical turn. The following tests were performed without the aid of lip reading in the two patients implanted with a single channel cochlear implant of 3M-House design. Lower frequency components of the speech signals were digitally delayed with a Sony SDP-777 ES surround processor. The results indicated that the optimal delay time for identification of /i/, /e/ and /u/ needed longer delay time, while that of /a/ and /o/ need shorter delay time, corresponding to the difference between the first and second formant of each vowel. Comparison of vowel perception with and without delay coding showed that vowel identification with delay coding was superior to that without it; 30% vs. 16% in case 1, and 48% vs. 30% in case 2.

Adult↗
PubMed1989

[The effect of intravenous administration of xylocaine for the treatment of tinnitus].

One hundreds and forty-nine patients (221 ears) suffering from tinnitus were treated by an intravenous administration of Xylocaine. Xylocaine, 1mg per kg, was administered once a week. The immediate effect of Xylocaine on tinnitus was evaluated subjectively for all the patients. The long term effect in 57 patients who received Xylocaine administration more than 12 times was also analyzed. The results can be summarized as follows. 1. Short and long term relief of tinnitus was obtained in 165 of 221 ears (74.7%) and in 35 of 57 cases (61.4%), respectively. 2. This therapy was more effective in old patients and in the patients with low pitch tinnitus, or with positive residual inhibition. 3. The numbers of the effective cases increased after the 8th time administration of Xylocaine. Thus we recommend the Xylocaine administration at least 8 times. 4. The results of the loudness balance test were not correlated with the change of the subjective improvements. 5. The suppressive effect of tinnitus by injecting saline solution intravenously was recognized in 24 of 73 cases. At present, repeated administration of Xylocaine would be one of the most significant therapies of tinnitus.

Adolescent↗
PubMed1988

Binding of [3H]phencyclidine to adrenal medullary cells: inhibition of 22Na influx, 45Ca influx, 86Rb efflux and catecholamine secretion caused by carbachol and veratridine.

In bovine adrenal medullary cells, phencyclidine inhibited carbachol-induced influx of 22Na, 45Ca and secretion of catecholamines in a concentration-dependent manner with a similar potency (IC50 7.0 microM). Phencyclidine also suppressed veratridine-induced influx of 22Na, 45Ca and secretion of catecholamines (IC50 60.0 microM). High K-induced 45Ca influx and catecholamine secretion were not affected by phencyclidine. In the cells preloaded with 86Rb (an alternative tracer for 42K), phencyclidine inhibited the efflux of 86Rb caused by carbachol (IC50 10.0 microM) or by veratridine (IC50 56.0 microM), but had no effect on high K-induced 86Rb efflux. [3H]Phencyclidine bound specifically to adrenal medullary cells, and binding was saturable, reversible and with two different equilibrium dissociation constants (4.3 and 77.4 microM). In a competition experiment, the specific binding of [3H]phencyclidine was not inhibited by carbachol, muscarine, D-tubocurarine, hexamethonium, tetrodotoxin, veratridine and scorpion venom. The present findings suggest: (1) phencyclidine does not inhibit voltage-dependent Ca channels and Ca-dependent K channels; (2) phencyclidine binds to two populations of sites, each of which is functionally linked to nicotinic receptor-ion channel complex and to voltage-dependent Na channels, and inhibits Na influx caused by carbachol and veratridine. Inhibition of Na influx by phencyclidine leads to the reduction of Ca influx, K efflux and catecholamine secretion caused by carbachol and veratridine.

Adrenal Medulla↗
PubMed1988

Effects of protonophores on the synthesis of catecholamines and the intracellular pH in cultured bovine adrenal medullary cells.

The protonophores carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP) and carbonyl cyanide m-chlorophenylhydrazone (CCCP) stimulated the synthesis of 14C-catecholamines from [14C]tyrosine in cultured bovine adrenal medullary cells. The stimulatory effect of CCCP but not of FCCP was partially dependent on extracellular Ca2+. CCCP but not FCCP increased the influx of 45Ca2+ to the cells. When cells were incubated with either CCCP or FCCP (0.01-0.2 microgram/ml), the intracellular pH fell from 7.2 to 6.3-6.5 and catecholamine synthesis increased. Tyrosine hydroxylase activity in a soluble fraction prepared from cultured adrenal medullary cells was measured after incubation of the cells with FCCP or CCCP. Although FCCP did not affect the activity of the enzyme, CCCP caused a stable activation of it which was dependent on extracellular Ca2+. Since the optimal pH of soluble tyrosine hydroxylase is around 6.0 in adrenal medullary cells, FCCP may increase the synthesis of catecholamines by shifting the intracellular pH toward it. In addition to this mechanism, CCCP may enhance the synthesis of catecholamines by a Ca2+-dependent mechanism.

Adrenal Medulla↗
PubMed1988

Experiments on antidromic evoked potentials of the facial nerve. A possible electroneurodiagnostic examination of intratemporal facial nerve paralysis.

Registering of AEPs of the facial nerve was attempted both in animals and in human subjects. In animal experiments using cats and guinea pigs, electrical stimulus was given to the zygomatic branch. The neural responses registered from the electrode placed on the fallopian canal or on the posterior wall of the external auditory canal were verified to be the AEP. The AEP appeared to be a sensitive and simultaneous indicator of the neural compression damage. In the human experiments, the three major peripheral branches were transcutaneously stimulated, and the AEPs were registered in the depth of the external auditory canal. The marginal mandibular branch was thought to be the most suitable branch of the transcutaneous stimulation for human application. The AEPs registered from a patient with Bell's palsy was demonstrated.

Animals↗
PubMed1988

Experimental study on autograft material for repair of round window rupture.

The healing process following experimentally produced rupture of the round window (RW) and subsequent closure with autograft materials were investigated in guinea pigs. The covering materials studied were fascia and perichondrium, both of which were placed over the RW after extensive rupturing of the RW membrane. The grafts were observed 1, 2, and 3 months after the operation. No substantial difference in the results for the two materials could be discerned. They adhered to the surrounding bone and were incorporated into the RW membrane within 3 months.

Animals↗
PubMed1988

Pressure transmission properties from the externa ear canal to the inner ear. An experimental study using guinea pigs.

The inner ear pressure (PIE) in response to pressure changes in the external ear canal was measured in guinea pigs while alternatively opening and closing the perforation of the otic bulla. When the bulla was opened, only a transient degree of applied pressure was transmitted to the inner ear and the amplitude of the PIE was smaller than that of the corresponding PIE when the bulla was closed. This was because the applied pressure was exclusively transmitted to the inner ear via the ossicular chain. When the otic bulla was closed, the pressure was transmitted not only via the ossicular chain but also via the round window (RW) through the middle ear cavity. When the bulla was closed, the amplitude of PIE was larger by a positive pressure load than by the corresponding negative one. The amplitude of PIE showed a linear relationship to ear canal pressure of at least within the +/- 200 mmH2O range, as long as pressure was slowly applied to the ear canal. When the loading pressure was abruptly changed, a bouncing response, possibly reflecting elasticity of the RW, was evoked, which diminished or disappeared when the round window was artificially ruptured.

Acoustic Impedance Tests↗
PubMed1988

Implantable hearing aid in fourteen patients with mixed deafness.

An implantable hearing aid (IHA) in which the stapes was directly driven by a ceramic vibrator of bimorph design was applied to fourteen patients with mixed deafness of varying degree due to chronic otitis media. In the partial IHA system, only the output transducer and secondary coil are implanted, the remainder of the components such as microphone, amplifier, battery and primary induction coil remain in the location behind the auricle. The vibrator was activated by an electric signal transmitted electromagnetically through the induction system from the outer unit. All the patients admitted that sound quality provided by the IHA was natural, clear and easy to hear without causing fatigue in long-term use. Speech discrimination test under noise circumstance showed that acoustic perception by the IHA was superior to that by a conventional hearing aid. In four patients, however, the implanted unit was replaced with a new one due to recurrence of cholesteatoma, head trauma, and accidental disruption of wire by manipulating the ear canal. They regained good hearing after re-implantation.

Adult↗
PubMed1987

Effects of alpha 2-adrenergic agonists on carbachol-stimulated catecholamine synthesis in cultured bovine adrenal medullary cells.

We examined the effects of alpha 2- and alpha 1-adrenergic agonists on synthesis of catecholamines in cultured bovine adrenal medullary cells. Clonidine, an alpha 2-adrenergic agonist, inhibited carbachol-stimulated synthesis of [14C]catecholamines from [14C]tyrosine in a concentration-dependent manner. Clonidine also inhibited carbachol-induced uptake of 45Ca2+ into cells at concentrations similar to those that inhibited the synthesis of [14C]catecholamines. Other alpha 2-adrenergic agonists, oxymetazoline and guanfacine, also strongly inhibited carbachol-stimulated synthesis of [14C]catecholamines. alpha 1-Adrenergic agonists, phenylephrine and norfenefrine, did not affect the synthesis. Tyrosine hydroxylase (EC 1.14.16.2) activity in a soluble fraction of cultured bovine adrenal medullary cells was assayed after gel filtration on a Sephadex G-25 column. Stimulation of the cells with carbachol increased the activity of tyrosine hydroxylase. Clonidine, oxymetazoline, and guanfacine all suppressed the carbachol-induced increase in activity of tyrosine hydroxylase in the cells. These results suggest that alpha 2-adrenergic agonists inhibit carbachol-stimulated synthesis of catecholamines by suppression of tyrosine hydroxylase activity, probably through the inhibition of Ca2+ uptake. However, the involvement of alpha 2-adrenoceptors in the inhibitory effects of alpha 2-agonists on catecholamine synthesis is still unsettled, since yohimbine failed to antagonize the inhibitory effect of clonidine on the synthesis in cultured bovine adrenal medullary cells.

2-Hydroxyphenethylamine↗
PubMed1987

Activation of tyrosine hydroxylase by micromolar concentrations of calcium in digitonin-permeabilized adrenal medullary cells.

In digitonin-permeabilized bovine adrenal medullary cells, Ca2+ (0.1-1.0 microM) caused an activation of tyrosine hydroxylase which was dependent on the presence of ATP. This Ca2+-induced activation of the enzyme was observed even in the presence of optimal concentration of either cyclic AMP or 12-O-tetradecanoylphorbol-13-acetate (TPA) which by itself increased the enzyme activity. Calmodulin inhibitors, trifluoperazine (TFP) and N-(6-aminohexyl)-5-chloro-1-naphtalenesulfonamide (W-7), had little effect on the Ca2+-evoked activation of enzyme. These results suggest that micromolar concentrations of Ca2+ activate the activity of tyrosine hydroxylase probably through a Ca2+-dependent phosphorylation in digitonin-permeabilized adrenal medullary cells although the protein kinase(s) responsible for it still remains to be determined.

Adenosine Triphosphate↗
PubMed1987

Implantable hearing aid. Report of the first human applications.

To our knowledge, this is the first report of human application of the partial implantable hearing aid. Direct driving of the stapes by an ossicular vibrator of piezoelectric ceramic bimorph is the fundamental mechanism of this device. Acoustic signals received by a microphone were transmitted to the external link coil after amplification. By means of electromagnetic induction, the internal coil placed under the retroauricular skin excited electroacoustic energy, which is transmitted to the vibrator directly coupled with the stapes. The device used in this first patient has been functioning for longer than one year. Excellent frequency response of the vibrator and highly efficient direct transmission of electroacoustic signals to the inner ear gave rise to acoustic perception of superior quality that could not be obtained by other surgical or rehabilitative measures.

Deafness↗
PubMed1987

Potassium channels in cultured bovine adrenal medullary cells: effects of high K, veratridine and carbachol on 86rubidium efflux.

To investigate the K permeability mechanism(s) in cultured bovine adrenal medullary cells, we measured the effects of high K, veratridine and carbachol on 86Rb efflux from the 86Rb preloaded cells. In non-stimulated cells, the basal efflux of 86Rb into Krebs-Ringer phosphate buffer containing 5.6 mM K proceeded gradually at the rate of 0.7% of cell 86Rb per min. High K caused a rapid 86Rb efflux; it was considerably reduced in Ca free medium. Mn, Co and Mg strongly inhibited high K-induced 45Ca influx and 86Rb efflux. Veratridine induced a sustained 86Rb efflux; it was inhibited by tetrodotoxin and abolished in Na free sucrose medium, but little affected in Ca free medium. Carbachol evoked a rapid and transient efflux of 86Rb; it amounted to 16.9% of cell 86Rb during 1 min. Carbachol-induced 86Rb efflux was inhibited by hexamethonium and d-tubocurarine. Nicotine caused 86Rb efflux, but muscarine had no effect. Carbachol-induced 86Rb efflux was substantially reduced in Na free sucrose medium, but little affected in Ca free medium. Mn, Co and Mg strongly reduced carbachol-induced 45Ca influx, but they did not appreciably alter carbachol-induced 22Na influx and 86Rb efflux. These results suggest that adrenal medullary cells have, at least, three distinct types of K permeability mechanisms: (1) basal K efflux, (2) Ca dependent K efflux, and (3) Na dependent K efflux. It seems that nicotine receptors mediate K efflux by increasing Na influx via nicotinic receptor-associated ionic channels rather than Ca influx via voltage dependent Ca channels.

Adrenal Medulla↗
PubMed1987

Multiple facial suspensions in protracted facial palsy.

Primary objective of multidirectional tractions of the facial muscles for protracted facial paralysis is to restore the facial symmetry. The facial suspension by multiple fascial strips in conjunction with other complemental minor surgical procedures realizes these complex tractions. Deformities requiring surgical procedures, regionally classified, are indicated for surgery as follows: 1) drooping of the eyebrow and upper eyelid, and loss of frontal creases, 2) lagophthalmos and ptosis of the lower eyelid, and 3) drooping of the cheeks and lips, and loss of the nasolabial fold. The multifascial suspension is a valuable adjunct to facial nerve surgery. It is capable of alleviating facial asymmetry due to paralysis and suppresses abnormal associated movements subsequent to surgical repair of facial nerves.

Adult↗
PubMed1987

Intracellular pH and catecholamine synthesis in cultured bovine adrenal medullary cells: effect of extracellular Na+ removal.

Incubation of cultured bovine adrenal medullary cells in Na+-free sucrose medium or in Na+-free Cs+ medium enhanced the synthesis of 14C-catecholamines from [14C]tyrosine about two- to threefold or sixfold, respectively. The increment of 14C-catecholamine synthesis produced by Na+-free medium was partially dependent on the presence of Ca2+ in the medium. Dibutyryl cyclic AMP also stimulated the synthesis of 14C-catecholamines in adrenal medullary cells, and the effects of Na+ removal and dibutyryl cyclic AMP (5 mM) on the synthesis were almost additive. The intracellular pH measured by using a weak acid 5,5-dimethyloxazolidine-2,4-dione was 7.14 in control cells and when Na+ was replaced by sucrose or Cs+, it shifted down to 6.56 or 5.66, respectively. The fall in intracellular pH and the stimulation of 14C-catecholamine synthesis were similarly dependent on the concentration of Na+ in the medium. The optimal pH of soluble tyrosine hydroxylase was 5.5-6.0 both in control cells and in cells incubated in Na+-free medium. These results suggest that removal of extracellular Na+ increases the synthesis of catecholamines, at least in part, by shifting the intracellular pH toward the optimal pH of tyrosine hydroxylase.

Adrenal Medulla↗