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Biomedical subjects

T Takasaka

Publications and source records attributed to T Takasaka.

At least 163 records · Page 9Linked to original sources
PubMed1993

Sympathetic and CGRP-positive nerve supply to the endolymphatic sac of guinea pig.

The distribution of sympathetic fibers and calcitonin gene related peptide (CGRP)-positive fibers was examined in the endolymphatic sac of 10 guinea pigs by using immunohistochemical techniques to demonstrate tyrosine hydroxylase (TH) and CGRP. A meshwork of TH-positive fibers, found around the sigmoid sinus, sent branches to the distal and the intermediate parts of the endolymphatic sac. In these areas. TH-positive fibers traveled freely from blood vessels and formed a loose plexus beneath the lining epithelium. Such fibers were rare in proximal portion of the endolymphatic sac and in the endolymphatic duct. Seven days after elimination of the ipsilateral superior cervical ganglion, some of the TH-positive fibers were gone, however, there were still a few fibers in the endolymphatic sac as well as around the sigmoid sinus, thus their origin remains obscure. CGRP-positive fibers also branched from the fibers around the sigmoid sinus, and were distributed throughout the endolymphatic sac, some occasionally extending to the endolymphatic duct. They not only formed a dense plexus in the sublining space, but also spread through the lining cell layer. Elimination of the ipsilateral superior cervical ganglion did not affect the distribution of CGRP-positive fibers, indicating that they are probably not sympathetic fibers.

Animals↗
PubMed1993

Reconstitution of immunological imbalance in SCID mice given tonsillar mononuclear cells from patients with IgA nephropathy.

IgA nephropathy (IgAN) is thought to be mediated by the glomerular deposition of circulating immune complexes containing IgA as the major antibody component. Tonsillitis often precedes IgAN, and tonsillectomy is an efficient treatment of IgAN. Thus, the tonsil may cause initial and/or progressive events leading to IgAN. To determine the pathological features of tonsillar lymphoid cells, we transferred tonsillar mononuclear cells from IgAN patients to SCID mice. Although human IgG-, IgM- and IgA-positive cells were detected in the spleens of SCID-Hu mice, they failed to reproduce the increase in serum IgA level and glomerular deposition. These results suggest that other factors are needed for the progression of IgAN.

Animals↗
PubMed1993

Effects of free radicals on the intracellular calcium concentration in the isolated outer hair cell of the guinea pig cochlea.

The cytosolic free calcium concentration ([Ca2+]i) isolated from the cochlear outer hair cell (OHC) of the guinea pig was measured using microfluorimetric imaging technique and the effects of free radicals were investigated. Hypoxanthine (HX) plus xanthine oxidase (XO) induced a rise in [Ca2+]i in the presence of external Ca2+. Elimination of external Ca2+ (pCa = 7) did not show an increase in [Ca2+i, indicating that the increased [Ca2+]i is dependent on external Ca2+. The elevation of [Ca2+]i induced by HX-XO was reduced by addition of superoxide dismutase or nifedipine but not by addition of catalase. A single admission of HX or XO failed to affect [Ca2+]i. These findings suggest that superoxide anion generated in the OHC increases the Ca2+ influx across the membrane, presumably leading to some pathological changes in the acoustic transduction by modulating the OHC motility.

Animals↗
PubMed1993

Differential physiologic effects of perfusion of scala tympani versus scala vestibuli in the ischemic cochlea.

The effectiveness of perilymphatic perfusion with oxygenated artificial media upon the endocochlear potential (EP) was measured during systemic ischemia in the guinea pig. Differences in the effects of perfusion of the two perilymphatic scalae were determined. Perfusion of scala vestibuli with oxygenated artificial perilymph at a high flow rate resulted in complete recovery of the EP to the pre-ischemic level, whereas perfusion of scala tympani with the same medium was unable to effect complete recovery. The recovery obtained by perfusion of scala tympani was about half that obtained of scala vestibuli. The pO2 in scala media was measured during perfusion by means of oxygen-sensitive microelectrodes. perfusion of scala vestibuli led to an approximately two-fold higher pO2 in scala media than perfusion of scala tympani. During perfusion, the pO2 in scala media varied dependent upon depth of electrode insertion, with a gradient decreasing toward the stria vascularis, a direction opposite to that seen under normal metabolic conditions. These findings suggest that, in the ischemic cochlea, oxygen enters scala media more easily from scala vestibuli across Reissner's membrane than from scala tympani via the basilar membrane/organ of Corti complex.

Animals↗
PubMed1993

Fine structure of the lamina basilaris of guinea pig cochlea.

The lamina basilaris of guinea pig cochlea was studied with SEM after trypsin treatment, and with TEM of resin sections and deep-etching replicas. The lamina consists of radial, evenly compacted filaments in the zona arcuata, and radial, discretely bundled filaments in the zona pectinata. In both zones, elementary filaments measured about 12 nm in thickness on the replica. The filaments formed more or less irregular passing bridges with each other and, eventually, a three-dimensional network which was continuous with the basement membrane under the supporting cells.

Animals↗
PubMed1993

[Three patients with gas gangrene of the head and neck].

Three patients with non-clostridial gas gangrene of the neck are reported. Patient 1 was a 57-year-old man, patient 2 a 63-year-old woman, and patient 3 a 44-year-old man. All three were treated by thorough debridement and precise administration of antibiotics. We also discuss 26 cases (including our 3) of gas gangrene of the head and neck, reported in Japan from 1975 to 1992, from which the following data were obtained: 1. The 26 patients consisted of 17 males and 9 females. 2. They ranged in age from 2 to 88 years, with a mean 56.5 years. 3. Causes included acute pharyngolaryngeal inflammation (46%), dental disease (27%), trauma (8%) and unknown etiology (19%). 4. As a result of bacteriological assessment, the condition was found to be attributable to Clostridium in only 2 patients, and in the remainder the condition was non-clostridial. 5. The mortality rate was 15%. The patients who died were at least 80 years old, and their prognosis had been poor. 6. CT was useful for diagnosis and treatment.

Adult↗
PubMed1993

[Expression of epidermal growth factor receptor in squamous cell carcinoma of the head and neck].

Localization of epidermal growth factor receptor (EGFR) was investigated immunohistologically in 68 untreated patients with squamous cell carcinoma of the head and neck regions. These patients consisted of 16 with cancer of the lips and mouth, seven with mesopharyngeal cancer, six with epipharyngeal cancer, 15 with hypopharyngeal cancer, 10 with laryngeal cancer, 12 with maxillary cancer and two with other tumors (cancer of the auricle and cancer of the eyelid in one patient each). The patients consisted of 57 men and 11 women, with a mean age of 60 years. In cases with a normal oral mucosa, marked expression of EGFR was observed in the epithelial cell membrane, while expression decreased toward the luminal surface. Cancer cells also showed positive staining of EGFR in all patients, but the intensity of staining was inconsistent among them. Among the 32 patients in whom the staining intensity of EGFR was equal to or weaker than that in basal cells of the normal oral mucosa, 12 patients had lymph node metastasis. Twenty-eight of the 36 patients in whom the staining was stronger than that in the normal cells had lymph node metastasis, suggesting that overexpression of EGFR in carcinoma cells is a risk factor for lymph node metastasis of head and neck cancers (P < 0.005). On the other hand, there were no obvious relationships between either the size or the degree of keratinization of the primary lesion and EGFR expression.

Adult↗
PubMed1993

Sodium extrusion mechanism in mammalian cochlear outer hair cell.

Intracellular sodium concentration ([Na+]i) in isolated outer hair cells (OHCs) of guinea pig cochlea was measured by microfluorimetric method using sodium binding benzofuran isophthalate. An application of ouabain increased [Na+]i. Our results suggest that OHCs have the definite activity of Na+/K+ ATPase.

Animals↗
PubMed1993

In vitro activity of ototopical drops against middle ear pathogens.

Five types of ear drops were each assessed for effectiveness on the basis of the in vitro antibacterial activity. Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), and Pseudomonas aeruginosa isolated from purulent otitis media were evaluated by comparative analysis. Otic drops containing new fluorinated quinolones, Ofloxacin and NY-198, showed high in vitro activity against all the bacteria. Cortisporin expressed moderate activity against P. aeruginosa and relatively weak activity against S. aureus and MRSA. Bestron and Fosmicin possessed low activity against three clinical isolates. Otic drops containing the new quinolones may be effective for treating purulent otitis media infected by MRSA and P. aeruginosa.

Anti-Bacterial Agents↗
PubMed1992

Effects of Ca2+ antagonists and aminoglycoside antibiotics on Ca2+ current in isolated outer hair cells of guinea pig cochlea.

The effects of various Ca2+ antagonists and aminoglycoside antibiotics on the Ca2+ channel in isolated outer hair cells of the guinea pig were investigated using a whole-cell patch-clamp technique. The inhibitory action was in the order of La3+ much greater than Cd2+ much greater than Ni2+ greater than Co2+ for inorganic Ca2+ antagonists, and flunarizine = nicardipine greater than omega-conotoxin greater than methoxyverapamil = diltiazem much greater than amiloride for organic ones. Aminoglycoside antibiotics also had antagonistic effects on the Ca2+ channel.

Aminoglycosides↗
PubMed1992

Glycine response in isolated dorsal cochlear nucleus of C57BL/6J mouse.

Pharmacological properties of glycine (Gly)-induced Cl- current (ICl) in the dorsal cochlear nucleus (DCN) neurons acutely dissociated from C57BL/6J mouse were investigated in the whole-cell configuration of the patch-clamp technique. Gly-induced ICl increased in a sigmoidal manner with higher Gly concentrations. Strychnine blocked the Gly response competitively at low and non-competitively at high concentrations. Both glutamate (Glu) and N-methyl-D-aspartate (NMDA) responses were augmented by adding 10(-6) M Gly, at which concentration Gly did not induce any ICl. This facilitation was not affected by strychnine. Our results clearly show the existence of strychnine-sensitive and -insensitive glycine receptors in the DCN neurons.

Animals↗
PubMed1992

Na(+)-Ca2+ exchange in the isolated cochlear outer hair cells of the guinea-pig studied by fluorescence image microscopy.

The outer hair cell isolated from the guinea-pig was superfused in vitro and the cytosolic calcium concentration ([Ca2+]i) and sodium concentration ([Na+]i) were measured using fluorescence indicators. Under the resting condition, [Ca2+]i and [Na+]i were 91 +/- 9 nM (n = 51) and 110 +/- 5 mM (n = 12), respectively. Removal of external Na+ by replacing with N-methyl-D-glucamine (NMDG+) increased [Ca2+]i by 270 +/- 79% (n = 27) and decreased [Na+]i by 23 +/- 4 mM (n = 6). Both changes in [Ca2+]i and [Na+]i were totally reversible on returning external Na+ to the initial value and were inhibited by addition of 0.1 mM La3+ or 100 microM amiloride 5-(N,N-dimethyl) hydrochloride. Elevation of external Ca2+ ions to 20 mM reversibly decreased [Na+]i by 8 +/- 6 mM (n = 5). Moreover, the chelation of the intracellular Ca2+ with 1,2-bis (2-aminophenoxy) ethane-N,N,N',N'-tetraacetic acid (BAPTA) exerted an inhibitory action on the NMDG(+)-induced reduction in [Na+]i. Exposure to 5 mM NaCN for 2 min significantly and reversibly increased [Ca2+]i by 290 +/- 37% (n = 5), but did not affect the [Ca2+]i elevation induced by the NMDG+ solution. The rise in [Ca2+]i induced by the NMDG+ solution was not enhanced by ouabain pretreatment. Addition of ouabain did not alter the [Na+]i. The present results are best explained by the presence of an Na(+)-Ca2+ exchanger in cell membrane and indicate that the activity of Na+/K+ pump is poor in outer hair cells.

Amiloride↗
PubMed1992

Quantitative carbohydrate analyses of the tectorial and otoconial membranes of the guinea pig.

Carbohydrate composition of the tectorial membrane (TM) and the otoconial membrane (OM) of the guinea pig was analyzed after hydrolysis, using high-performance anion-exchange chromatography and pulsed amperometric detection. Both of the tissues were highly glycosylated; the carbohydrate content being 24-42% of protein. GlcN, Gal, Glc and Man were found to be the major component sugars of TM, whereas little GalN was found. Fuc and NANA were also present, but NGNA was not detectable. After digestion with thermolysin for solubilization, OM was separated into two fractions: insoluble mineral particles of the otoconia (OM-ppt) and a soluble fraction from the gelatinous layer (OM-sup). These two fractions showed distinct carbohydrate composition from each other. Further analyses using glycosidases revealed that TM contained asialyl and monosialyl but little di-, tri- and tetrasialyl N-glycosides, and OM-sup did not seem to be susceptible to endo-beta-galactosidase, which is known to cleave some N-acetyl-polylactosamine and keratan sulfate. Based on these analyses, it can be suggested that most of the carbohydrates in TM are likely to be asialyl and monosialyl N-glycosides. N-Glycosides may be predominant in the otoconia as well, and a polymer structure consisting of GlcN(Ac) and Gal other than N-acetyl-polylactosamine may exist in the gelatinous layer of OM. O-Glycosylation of the usual type appeared to be minor in all the fractions.

Acetylation↗
PubMed1992

Membrane potential measurement in isolated outer hair cells of the guinea pig cochlea using conventional microelectrodes.

Membrane potential of the isolated outer hair cells (OHCs) from the guinea pig cochlea was measured using conventional microelectrodes filled with 200 mM KCl. The resting membrane potential during superfusion with the standard physiological saline solution containing 3.5 mM K+ was -47.3 +/- 1.4 mV (N = 72), which was higher than those previously reported for isolated OHCs studied by using microelectrodes. Addition of ouabain (10(-5)-10(-3) M), the specific Na+, K+ ATPase inhibitor, depolarized the cell slowly and progressively, indicating the presence of low but definite Na+, K+ ATPase activity in the plasma membrane of OHCs. The magnitude of membrane potential was mainly dependent on the extracellular K+ concentration ([K+]O). A ten-fold increase of [K+]O depolarized the membrane potential by 49.6 +/- 1.0 mV (N = 58). A decrease of [Na+]O to one tenth of the control hyperpolarized the membrane potential by about 2 mV. Decreasing extracellular Cl- from 131.3 mM to 27.5 mM did not cause a significant change in the membrane potential. Using the Goldman-Hodgkin-Katz equation, assuming a negligible contribution of Cl- to the membrane potential and total monovalent cat ion concentration of the cytosol similar to the extracellular fluid, we calculated the permeability ratio of K+ versus Na+ to 131 +/- 19 and intracellular K+ concentration to 33.3 +/- 1.9 mM.

Animals↗
PubMed1992

Intracellular pH regulation in isolated cochlear outer hair cells of the guinea-pig.

1. The intracellular pH (pHi) regulation mechanisms of the outer hair cell (OHC) isolated from the guinea-pig were studied using fluorescence ratio imaging microscopy. 2. The OHC pHi in the resting condition was 7.26 +/- 0.08 (mean +/- S.D., n = 49) when the standard solution buffered with HEPES-Tris was superfused. 3. Exposure to 25 mM-NH4+ in the absence of HCO3- caused biphasic changes in pHi; a transient increase (7.89 +/- 0.14, n = 22) followed by a slow decrease (7.57 +/- 0.12; mean +/- S.D.). Removal of external NH4+ by introducing the N-methyl-D-glucamine (NMDG+) solution in the absence of HCO3- markedly acidified the pHi to 6.38 +/- 0.12 with little pHi recovery. Subsequent application of the standard Na+ solution restored the pHi to the initial value. The recovery was inhibited by 0.5 mM-amiloride but not by 0.3 mM-DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid). 4. In the presence of HCO3-, removal of both external NH4+ and Na+ promptly caused an intracellular acidification followed by a pHi recovery. The pHi recovery from an acid load was inhibited by 0.3 mM-DIDS or 10 microM-NPPB (5-nitro-2-(3-phenylpropyl-amino)-benzoate). However, the pHi in the steady state in the presence or absence of HCO3- was not altered by addition of 0.5 mM-amiloride or NMDG+ solution. 5. The intracellular buffering power obtained from the NH4+ exposure and withdrawal was -15.1 +/- 8.7 mM (pH unit)-1 (n = 6) and -14.3 +/- 5.8 mM (pH unit)-1, respectively. 6. Replacement of external Cl- with gluconate in the HCO3- solution increased the pHi from 7.22 +/- 0.12 to 7.51 +/- 0.20 (n = 6), which was inhibited by 0.3 mM-DIDS. Moreover, addition of DIDS to the HCO3- solution increased the pHi by 0.13 +/- 0.08 (n = 8). 7. When the external standard solution buffered with HEPES-Tris was replaced with the HCO3- solution, the basal pHi (7.27 +/- 0.10) was promptly acidified to 6.87 +/- 0.10 then relaxed slowly to 7.00 +/- 0.15 (n = 16). 8. The pHi showed an initial alkalinization and a subsequent slow acidification after the HCO3(-)-free standard solution replaced the HCO3- solution. The slow acidification was inhibited by low external Cl- concentration or by addition of 0.3 mM-DIDS.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetazolamide↗
PubMed1992

Middle ear inflation with a gas mixture.

We studied the middle ear (ME) pressure in 13 atelectatic ears to evaluate the effect of politzerization or ME inflation by a catheter using both room air and a gas mixture. The gas contained 12% O2, 6% CO2 and 82% N2. Tympanometry was performed before and after the treatment. The elevated ME pressure induced by the treatments, whether with room air or the gas mixture, declined rapidly within the first 30 min. However, at 35 and 45 min after the treatment with room air, the mean decrease in pressure was significantly greater than with the gas mixture, which might be due to slow oxygen absorption through the ME mucosa.

Acoustic Impedance Tests↗