Biomedical subjects

S Ebihara

Publications and source records attributed to S Ebihara.

At least 19 recordsLinked to original sources

PubMed1995

Gramicidin-perforated patch recording: GABA response in mammalian neurones with intact intracellular chloride.

1. By the development of a new perforated patch method using gramicidin, the effects of GABA on neurones dissociated from the rat substantia nigra pars reticulata (SNR) were examined without disturbing the intracellular chloride concentration. 2. Using the patch pipette solution containing gramicidin (100 micrograms ml-1), the access resistance dropped to less than 20 M omega within 40 min after making the gigaohm seal. 3. Under current-clamp conditions, GABA caused a hyperpolarization accompanied by a blockade of spontaneous firing. Under voltage clamp at a holding potential (Vh) of -50 mV, GABA evoked an outward current by way of bicuculline- and picrotoxin-sensitive GABAA receptors. 4. A 10-fold change of extracellular chloride concentration resulted in a 58 mV shift of the reversal potential of GABA-induced outward current (EGABA), indicating that the membrane behaves like a chloride electrode in the presence of GABA. 5. The intracellular chloride activities (aCli), calculated with the Nernst equation using both extracellular chloride activity and EGABA values, ranged from 2.8 to 19.7 mM with a mean value of 9.5 mM. The aCli was not affected either by different pipette solutions or by different holding potentials more hyperpolarized than -40 mV. 6. In the recording from SNR neurones in brain slice using the gramicidin-perforated patch-clamp technique, the inhibitory and excitatory postsynaptic currents were recorded in different current directions and the former was blocked by bicuculline. 7. In conclusion, the gramicidin-perforated patch method will disclose previously unknown aspects of biological responses involving Cl-.

Amphotericin B↗

PubMed1995

Pericranial muscle hardness in tension-type headache. A non-invasive measurement method and its clinical application.

Using a new method to measure the hardness of pericranial muscles, the role of muscle factors in tension-type headache was evaluated. In 223 normal healthy subjects, the hardness of trapezius muscles was 82 +/- 15 kPa/cm (mean +/- SD). The muscle hardness in women, 92 +/- 17 kPa/cm, was significantly greater than that in men, 74 +/- 14 kPa/cm (P < 0.01). Trapezius muscles were significantly harder than paraspinal posterior neck muscles measured at the level of the fifth cervical vertebra (71 +/- 13 kPa/cm; n = 26) but a significant correlation in muscle hardness did exist between these two muscle groups (r = 0.89, P < 0.001). Muscle hardness did not show a significant correlation with advancing age, blood pressure or subjective feeling of stiffness in the shoulder. A significant correlation was noted between the muscle hardness measured by the present method and the stiffness scores evaluated by manual palpation. In patients with tension-type headache (n = 60), the hardness of trapezius muscles, 114 +/- 24 kPa/cm (mean +/- SD), was significantly greater than that in normal subjects (P < 0.01). Twenty-six patients (43% of the total) showed significantly high values which exceeded the mean +/- 2 SD (113 kPa/cm) of the normal value, while the remaining patients (57%) constituted a high normal group. The hardness of posterior neck muscles measured in 27 patients (99 +/- 21 kPa/cm) was also significantly greater than that in normal subjects (P < 0.01). There was no significant difference in muscle hardness between episodic tension-type headache and chronic tension-type headache.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Effects of suprachiasmatic lesions on circadian rhythms of blood pressure, heart rate and locomotor activity in the rat.

To determine whether the circadian rhythms in blood pressure (BP), heart rate (HR) and locomotor activity are controlled by an internal biological clock located in the suprachiasmatic nucleus (SCN), we continuously measured these parameters in SCN-lesioned rats using a newly developed implantable radiotelemetry device and a computerized data collecting system. Although SCN-lesioned rats showed a weak but significant 24-h periodicity in BP and HR under light-dark (LD) cycles, BP, HR and locomotor activity became completely aperiodic under constant dark (DD) conditions. The amount of locomotor activity was significantly reduced in SCN-lesioned rats compared to that in intact rats. BP tended to be higher in SCN-lesioned rats, but the differences were significant only in the comparison of systolic blood pressure (SBP) under LD and DD (p < 0.05) and of mean blood pressure (MBP) under LD (p < 0.05). HR in SCN-lesioned rats was significantly lower under LD (p < 0.05), but not under DD. The standard deviation and the variation coefficient of MBP, as indices of short-term variability of this parameter, were significantly larger in SCN-lesioned rats than in intact rats, while those of HR and locomotor activity did not differ significantly between SCN-lesioned and intact rats. These results indicate that the SCN is important not only for generating circadian rhythms of BP, HR and locomotor activity, but also for buffering the short-term variability of BP in rats.

Animals↗

PubMed1995

[Changes in respiratory function before and after laryngectomy].

Many patients with head and neck cancer have a smoking history, and pulmonary complications frequently lead to post-operative death. Due to technical problems, spirometric pulmonary function tests are rarely performed in patients with laryngectomy. The purpose of this study is to evaluate respiratory function in patients with laryngectomy. We made a tracheal mask with a heat and moisture exchanging baseholder, and used it for spirometry. Eight patients with laryngectomy, including 5 with laryngeal cancer and 3 with hypopharyngeal cancer, were studied. Arterial blood gas analysis and pulmonary function measurements, such as VC, % VC, FEV1.0% and V25/height (V25/HT), were evaluated before and after laryngectomy. Statistical analysis of the data was performed with the Wilcoxon rank-sum test. The following results were obtained: 1) No statistically significant changes in arterial blood gases and FEV1.0% were found. 2) A statistically significant decrease in VC was found after total laryngectomy (p < 0.05). 3) A statistically significant decrease in V25/HT, which reflects small air way closure of the lung, was observed after total laryngectomy (p < 0.05). In all cases, the V25/HT value was below normal limits. We concluded that the decrease in VC was caused by a decrease in dead space in the upper airway, and that V25/HT may be a good parameter for evaluation of pulmonary function after laryngectomy.

Aged↗

PubMed1995

[Fourteen cases of malignant melanoma of the nasal cavity].

Fourteen cases of malignant melanoma of the nasal cavity were treated in our department during 31 years from 1962 to 1993. Ten were males and 4 were females. The ages ranged from 48 to 92 years old, with an average of 64.6 years. The chief complaints were epistaxis in 10 cases, nasal obstruction in 7, nasal cavity tumor in 1, and dull headache in 1. Histologically, 3 cases were amelanotic type, 3 oligomelanotic and 8 melanotic. The cellular types were classified as follows: 5 spindle and 9 large epitheloid cell types. Palliative treatment was performed in 1 patient, and 13 patients were treated radically. Local recurrences were seen in 8 patients, 9 regions; 3 near the posterior margin, 1 near the upper margin, 1 cheek, 2 ethmoid sinus, 1 maxillary sinus, and 1 uncertain. The cumulative survival rate among the 14 patients was 54.2% after 2 years and 31.0% after 5 years. One patient had local recurrence 13 years after surgical treatment.

Aged↗

PubMed1995

Malignant tumors of the nasal cavity: review of a 60-case series.

Sixty cases of primary malignant tumor of the nasal cavity treated in our hospital between 1962 and 1993 were reviewed. Males were affected 2.8 times more frequently than females. The age at the first consultation ranged from 11 to 92 years, with a mean of 55.1 years. The peak distribution was seen in the 6th decade. Twenty-six cases were epithelial malignancies (squamous cell carcinoma 15; adenocarcinoma 3; adenoid cystic carcinoma 3; undifferentiated carcinoma 3; mucoepidermoid carcinoma 1; malignant mixed tumor 1), while 34 cases were non-epithelial malignancies (malignant melanoma 14; malignant lymphoma 14; plasmacytoma 3; olfactory neuroblastoma 2; rhabdomyosarcoma 1). The most common symptom on presentation was nasal obstruction (66.7%), followed by epistaxis (55.0%). The first recurrence was local in 19 patients, whereas cervical lymph node metastasis occurred in three patients, bone metastasis in two, intraperitoneal metastasis in two, and brain metastasis in one. The overall five-year cumulative survival rate was 48.0%. The five-year survival rates for squamous cell carcinoma, malignant melanoma, and malignant lymphoma were 57.0%, 31.0%, and 40.0%, respectively.

Adolescent↗

PubMed1994

Application of in vivo microdialysis to pineal research in birds: measurement of circadian rhythms of melatonin.

Circadian rhythms of pineal melatonin release were measured in free-moving pigeons, Japanese quails, and chickens under light-dark cycles followed by constant dim light. Although melatonin levels differed among individual birds, circadian rhythms of melatonin were observed in all of them. Using this technique, we could examine phase shifts of melatonin rhythms and suppression of melatonin release by photic stimulation in pigeons. We could also examine effects of norepinephrine infusion on melatonin release. These results indicate that microdialysis is useful for the study of pineal melatonin rhythms in birds.

Animals↗

PubMed1994

Suramin and reactive blue 2 are antagonists for a newly identified purinoceptor on rat megakaryocyte.

1. The effects of purinoceptor antagonists on ATP-induced oscillatory K(+)-currents in rat isolated megakaryocytes were investigated. 2. Both reactive blue-2 (RB-2), a selective antagonist of the P2Y purinoceptor, purinoceptor, at concentrations of 0.3-10 microM and suramin, a non-selective P2 purinoceptor antagonist, at 1-30 microM blocked the ATP-induced oscillation in a concentration-dependent manner. 3. RB-2 and suramin also blocked the ADP-induced K(+)-current oscillation at the same concentration range as in the case of ATP. However, both suramin and RB-2 had no effect on thrombin- and inositol 1,4,5-trisphosphate (IP3)-induced K+ current oscillation, indicating that they act as specific purinoceptor antagonists. 4. Thus, the purinoceptors on megakaryocytes show the properties of the P2 subtype according to their blockade by antagonists.

Adenosine Diphosphate↗

PubMed1994

Gramicidin perforated patch-clamp technique reveals glycine-gated outward chloride current in dissociated nucleus solitarii neurons of the rat.

1. The inhibitory response of exogenously applied glycine was investigated in freshly dissociated rat nucleus tractus solitarii neurons under whole cell configuration using new perforated patch-clamp technique termed "gramicidin perforated patch technique," which maintains intact intracellular Cl- concentrations. 2. Using the gramicidin perforated patch technique, at a holding potential (VH) of -45 mV, glycine induced outward currents in a concentration-dependent manner with a EC50 of 4.0 x 10(-5) M and at a Hill coefficient of 1.5. In contrast, using the nystatin perforated patch technique, glycine induced inward currents at the same VH in a concentration-dependent manner with an EC50 of 4.9 x 10(-5) M and at a Hill coefficient of 1.2. 3. The glycine-induced outward currents were blocked by strychnine in a concentration dependent manner with an IC50 of 2.2 x 10(-8) M. The blockade was competitive. 4. The current-voltage relationship for the 10(-5) M glycine response showed a clear outward rectification. 5. Ten-fold change of extracellular Cl- with a large impermeable anion resulted in a 65 mV shift of the reversal potential of glycine-induced currents (EGly), indicating that the membrane behaves like a Cl- electrode in the presence of glycine. 6. The intracellular Cl- activity calculated from the EGly ranged from 7.3 to 18.2 mM, with a mean value of 13.3 mM. 7. The values of EGly in the individual neurons were significantly negative to the resting membrane potentials, suggesting the existence of active transport of Cl-.

Animals↗

PubMed1994

Differences in circadian photosensitivity between retinally degenerate CBA/J mice (rd/rd) and normal CBA/N mice (+/+).

Using the magnitude of phase shift of circadian locomotor rhythms induced by a single pulse of white fluorescent light, we compared the sensitivity of the circadian system to light in retinally degenerate mice and in normal mice. In the first experiment, phase response curves (PRCs) for 10-lux white light were generated in CBA/J mice with retinal degeneration (rd/rd) and CBA/N mice with normal retinas (+/+). Although large phase delays early in the subjective night and small phase advances in the late subjective night were observed in CBA/N mice, CBA/J mice showed only small phase delays early in the subjective night. In the second experiment, we found that the magnitude of phase shifts at circadian time (CT) 16 for delays and CT 24 for advances in CBA/J mice became larger with increasing light intensity, and that CBA/J mice could show the same amount of phase shift as CBA/N mice when higher intensities were used. These findings indicate that the differences in the shapes of PRCs are not due to differences in the nature of the oscillating system, but to differences in circadian photosensitivity between these strains. Because the genetic background for the rd loci was not completely identical in the CBA/N and CBA/J mice, it was possible that genes other than the rd gene might have caused different photosensitivity in these mice. Therefore, in the last experiment, we studied the circadian photosensitivity in F1 hybrids between CBA/N and CBA/J mice and in the backcross progeny with different genotypes (+/rd and rd/rd) obtained from the crossing between F1 hybrids between CBA/N and CBA/J mice and in the backcross progeny with different genotypes (+/rd and rd/rd) obtained from the crossing between F1 and CBA/J mice. In these mice with heterogeneous genetic backgrounds as well, mice with retinal degeneration were always less sensitive to light, suggesting that reduced circadian photosensitivity is caused by retinal degeneration. These results are discussed in relation to recent findings in retinally degenerate C57BL mice, which have been found to have normal circadian sensitivity to light.

Animals↗

PubMed1994

Effects of unilateral phrenic nerve denervation on diaphragm contractility in rat.

We examined the early effects of phrenic nerve denervation on the diaphragm muscle 1, 3, 7 and 14 days after unilateral denervation in rats. In the denervated hemidiaphragms, force frequency curves at 3, 7 and 14 days decreased significantly by 51%, 50% and 38% respectively of the peak tension of the force frequency curves of the diaphragms of rats with sham operation. Twitch tensions increased significantly at 14 days, and contraction times and half relaxation times slowed significantly at 3, 7 and 14 days. The tensions of denervated diaphragms at 5 min during the fatigue runs was significantly increased at 14 days. As determined by histological staining, the mean cross sectional area of fast-twitch fibers (type II) decreased significantly from 2,742 (sham) to 1,599 microns (14 days), but that of the slow-twitch fibers (type I) did not change significantly during the same period. These findings suggest that, during the first two weeks of denervation, fast twitch fibers (type II) atrophy more rapidly than slow twitch fatigue resistant fibers (type I), as confirmed by the contractile properties and histological findings.

Adenosine Triphosphatases↗

PubMed1992

Circadian rhythms of pineal melatonin release in the pigeon measured by in vivo microdialysis.

Circadian rhythms of pineal melatonin release were measured in freely moving pigeons (Columba livia) by in vivo microdialysis. The birds were placed in light-dark cycles with 12 h of light and 12 h of darkness (LD 12:12) or continuous dim light (LLdim) after LD 12:12. Although the level of melatonin was various, daily changes of melatonin with higher levels during the dark and lower levels during the light were observed in all of the birds examined. The daily changes of melatonin persisted in LLdim, indicating circadian nature of pineal melatonin release. Moreover pineal melatonin release was inhibited by acute exposure of light during the dark. These results indicate that microdialysis is useful for studying circadian pineal melatonin rhythms of birds.

Animals↗

PubMed1992

Analysis of thyroid carcinoma based on material registered in Japan during 1977-1986 with special reference to predominance of papillary type.

BACKGROUND: As geographic differences have been observed in the characteristics of thyroid carcinoma, an analysis was made on thyroid carcinoma in the iodine rich country of Japan. METHODS: A total of 10,973 patients with histologically confirmed thyroid carcinoma registered in Japan from 1977-1986 were analyzed. Cases detected incidentally at autopsy and cases of nonepithelial tumor were excluded. This series included approximately 27% of all thyroid carcinoma cases in Japan. RESULTS AND CONCLUSIONS: Histologic distribution showed that papillary carcinoma accounted for 78.4% of cases, follicular carcinoma accounted for 17.2%, medullary carcinoma for 1.4%, squamous cell carcinoma for 0.3%, and anaplastic carcinoma for 2.7%. There is a tendency in Japan to diagnose papillary carcinoma as follicular carcinoma and to diagnose malignant lymphoma as anaplastic carcinoma. It was considered that the percentage of papillary carcinoma was higher and the percentage of follicular carcinoma and anaplastic carcinoma was lower than foregoing values. The characteristics of thyroid carcinoma in Japan were described, and the low incidence of nonpapillary carcinoma compared with papillary carcinoma was discussed in relation to iodine excess as an etiologic factor.

Adolescent↗

PubMed1992

Modulation of NMDA receptors by ACh in the central nervous system.

The effect of acetylcholine (ACh) on N-methyl-D-aspartate (NMDA)-induced responses in neurons acutely dissociated from the rat nucleus basalis of Meynert (nBM) was investigated with a conventional patch-clamp technique. The whole-cell recording revealed that NMDA-induced inward current (INMDA) consisted of transient peak and successive steady-state components. With outside-out recording, these components were shown to have the identical single channel conductance. Pretreating the nBM neurons with the low concentration of ACh suppressed the peak component of INMDA, whereas the high concentration potentiated it. The modulatory action of ACh was observed in nBM neurons dissociated from mature rats. The action was deficient, however, in those from immature animals. These results suggest that ACh is either an inhibitory or an excitatory modulator of glutamatergic transmission in the central nervous system.

Acetylcholine↗

PubMed1992

Regional variation of excitatory and inhibitory amino acid-induced responses in rat dissociated CNS neurons.

Regional differences in glutamate (Glu), aspartate (Asp), gamma-aminobutyric acid (GABA) and glycine (Gly) responses in CNS neurons were investigated by means of the whole-cell mode of the patch-clamp technique. The neurons were freshly dissociated from rat cortex, limbic system (hippocampal CA1 region), diencephalon (ventromedial hypothalamus), medulla (nucleus paragigantocellularis lateralis) and spinal cord (spinal dorsal horn). The current amplitudes induced by Glu and GABA did not show any regional differences whereas those of Asp- and Gly-induced responses were significantly different among CNS regions. The enhancement of Asp response by Gly was observed in all regions, and the facilitatory ratio did not differ among these regions. Even though the NMDA response in cortical neurons was significantly greater than that in spinal neurons, the ratios of NMDA response facilitation by Gly were also the same in both regions. When the current amplitudes induced by individual amino acids were estimated for the unit surface area of respective neurons (current density), the Glu, Asp and Gly responses showed regional heterogeneity whereas the GABA response did not.

Amino Acids↗

PubMed1992

Strychnine-induced potassium current in CA1 pyramidal neurones of the rat hippocampus.

1. Direct actions of strychnine (Str) and brucine (Bru) on the dissociated hippocampal CA1 neurones of the rat have been investigated with the whole-cell mode of the patch-clamp technique. 2. At a holding potential (VH) of -20 mV, both Str and Bru elicited outward current at concentrations over 10(-5) M. The reversal potential of Str-induced current (EStr) was -77.8 mV, which was close to the K+ equilibrium potential (EK = -80.3 mV). The change in EStr for a ten fold change in extracellular K+ concentration was 58 mV, indicating that the membrane behaves like a K+ electrode in the presence of Str. 3. The concentration-response curves for Str and Bru were bell-shaped, and nearly maximum response occurred at 10(-4) M for Str and 3 x 10(-4) M for Bru. The maximum current amplitude induced by Bru was about 80% of that induced by Str. A transient 'hump' current appeared immediately after the wash-out of external solutions containing Str and Bru at concentrations higher than 10(-4) and 3 x 10(-4) M, respectively. 4. The Str-induced current (IStr) was antagonized by K+ channel blockers such as Ba2+, tetraethylammonium (TEA)-chloride, and 4-aminopyridine (4-AP) in a concentration-dependent manner. IStr was insensitive to glibenclamide, a blocker of ATP-sensitive K+ channels. 5. Internal perfusion with 10 mM BAPTA did not affect the Str-induced IK. Depletion of the intracellular Ca2+ store by caffeine had no effect, indicating that intracellular Ca2+ does not mediate the Str-induced activation of K+ conductance.6. Both guanosine-5'-0-3-thiotriphosphate (GTPyS) and guanosine-5'-O-thiodiphosphate (GDPPS) suppressed the Str-induced IK, the former action appearing more rapidly than the latter. The results suggest that the GTP binding proteins are involved in this Str response.7. When neurones were loaded with cholera toxin (CTX) or pertussis toxin (PTX) through a patch pipette, PTX suppressed the Str response whereas CTX did not, suggesting that G, and/or Go might be involved in the Str-induced IK.

Animals↗

PubMed1992

Voltage-dependent ionic currents in dissociated paratracheal ganglion cells of the rat.

1. Conventional whole-cell voltage-clamp technique was used to study the electrophysiological and pharmacological properties of voltage-dependent Na+, K+ and Ca2+ channels in parasympathetic neurones enzymatically dissociated from the paratracheal ganglia of rat trachea. The voltage-dependent Na+, K+ and Ca2+ currents (INa, IK and ICa) were separated by the use of ion subtraction and pharmacological treatments. 2. INa was activated by a step depolarization more positive than -50 mV and fully activated at positive potentials more than +10 mV. The inactivation phase of INa consisted of fast and slow exponential components (tau if and tau is, respectively). The tau if and tau is were voltage dependent and decreased with a more positive step pulse. 3. The time course for recovery of INa from the complete inactivation exhibited two exponential processes. 4. The reversal potential of INa was equal to the Na+ equilibrium potential (ENa) and resembled a simple Na+ electrode depending only on external Na+ concentration. 5. Tetrodotoxin (TTX) reduced INa without affecting the current kinetics in a concentration-dependent manner, and the concentration of half-maximal inhibition (IC50) was 6 x 10(-9) M. There was no TTX-resistant component of INa in any of the cells tested. 6. Scorpion toxin increased the peak amplitude of INa and prolonged the inactivation phase in a time- and concentration-dependent manner. In the presence of toxin, both tau is and the fractional contribution of the slow current component to total INa increased concentration dependently. 7. High-threshold (L-type) ICa was activated by a step depolarization more positive than -30 mV and reached a peak at near 0 mV in the external solution with 2.5 mM Ca2+. The current was inactivated to only a small extent (< 10%) during 100 ms of depolarizing step pulse. There was no low-threshold (T-type) ICa in this preparation. 8. The maximum ICa in individual current-voltage (I-V) relationships was saturated by an increase in extracellular Ca2+ concentration ([Ca2+]o). The I-V relationships were also shifted along the voltage axis to the more positive potential with increasing [Ca2+]o. 9. The inactivation process of the L-type ICa was dependent on Ca2+ influxes (ICa-dependent inactivation). 10. Relative maximum peak currents of divalent cations passing through the L-type Ca2+ channels were in the order of IBa > ICa > ISr. 11. Organic and inorganic Ca2+ antagonists blocked the ICa in a concentration-dependent manner.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1992

Lymphoscintigraphy of head-and-neck cancer.

To achieve the visualization of regional lymph nodes by lymphoscintigraphy, 21 patients with head-and-neck cancer were studied with the aid of 99mTc-labeled rhenium sulfur colloid (99mTc Re). Four injection sites were selected; the injections were given into the subcutaneous tissue of the parietal area of 11 patients, into the submucosa of the retromolar area of 6 patients, into the subcutaneous tissue of the postauricular area of 2 patients, and into the thyroid glands of 2 patients. Lymphoscintigraphy was done three hours after the injection. The cervical regions were visible in 85.7% of the patients on the affected side and in 90.5% on the healthy side. The visualization comprised the following regions: submental, submandibular, deep cervical, accessory, and supraclavicular regions. In total, 102 nodes were visualized on the affected side (average 4.8 per patient) and 110 nodes in the healthy side (average 5.5). Histologically, 15 of 21 patients had lymph nodes metastases and 6 did not. Of these 21 patients, 66.7% (14/21) had confirmed lymph node metastases in the visualized regions. This technique appears to be a relatively easy and efficient method of imaging the regional lymph nodes in head-and-neck cancer both before treatment and after neck surgery.

Aged↗