Search PubMed⌕ Search

Biomedical subjects

S Nishihara

Publications and source records attributed to S Nishihara.

At least 73 records · Page 4Linked to original sources
PubMed1993

Measurement of umbo vibration in human subjects--method and possible clinical applications.

A commercial laser doppler vibrometer (LDV) was used to evaluate umbo displacement at sound pressure levels of 60, 70, and 80 dB SPL at the tympanic membrane (TM) of six subjects. Thirty-five pure-tone test frequencies, five per octave, were tested from 140 to 19,433 Hz. A computer program (Tymptest) produced and controlled the tones as well as improved the signal-to-noise ratio of the LDV. The test took about an hour to perform and provided reproducible results in all subjects. In addition, measurement of umbo displacement using the same system was made in 15 fresh human temporal bones for comparison. Results in the humans revealed a relatively flat umbo displacement from 140 to 1000 Hz, with a gradually sloping roll-off of -8.25 dB per octave from 1000 to 7000 Hz. From 8000 to 14,000 Hz the roll-off increased to -12.5 dB per octave. At the mean resonant frequency of the middle ear, 1000 Hz, and an 80 dB SPL input, umbo displacement was 0.045 micron. The human temporal bones showed similar results. Possible future clinical applications of this measurement include the identification of ears with acoustically inefficient TMs (tin ears). By identifying and studying such ears we should be able to develop methods to improve their function and produce hearing threshold increases of 15 dB or more at key speech frequencies. In addition, analysis of umbo and TM vibration in reconstructed middle ears should help us achieve better postoperative hearing results.

Adolescent↗
PubMed1993

[A case of discrete type of subpulmonary stenosis].

We reported a 8-year-old girl having discrete type of subpulmonary stenosis. This patient was associated with atrial septal defect (ASD), valvular pulmonary stenosis, and persistent left superior vena cava (PLSVC). The incidence of this type of subpulmonary stenosis is less frequent than that of subaortic lesion. ASD was closed by the autologous pericardium and a transannular patch was used for enlargement of the right ventricular outflow tract followed by commissurotomy of the pulmonary valve and resection of subpulmonary discrete lesion. She was uneventful and postoperative pulsed doppler echocardiogram showed good results.

Child↗
PubMed1992

Transmission of change in the atmospheric pressure of the external ear to the perilymph.

In experiments using guinea pigs, the middle ear and perilymphatic pressures were simultaneously registered in response to pressure change in the external ear canal. In the first experiment, pressure was slowly loaded in the ear canal in the range of 200 mm H2O to -200 mm H2O. Pressure transmission to the perilymph was smaller when the bulla was open to the outside than when it was closed. It was significantly impaired by disruption of the ossicular chain and especially by closure of the round window. The data indicate that air volume in the middle ear cavity plays an important role in transmission of slowly changing atmospheric pressures. In the second experiment, the eustachian tube was closed and the pressure was changed in the range of 1000 mm H2O to -1000 mm H2O. The middle ear and perilymphatic pressures increased or decreased corresponding to the loading pressure in the range of 400 mm H2O and -200 mm H2O. Beyond these levels, response rate of the middle ear pressure decreased and perilymphatic pressure declined in spite of further increase in loading pressure. The increase in pressure difference between the middle ear and the inner ear might cause disruption of the round and/or oval windows.

Animals↗
PubMed1992

[A case of a right subclavian arterial aneurysm associated with the aortic arch anomaly in childhood].

Aneurysms in the subclavian arteries are extremely rare in childhood. A 7-year-old boy was admitted with hoarseness and abnormal shadow in the chest film. Radiologic studies demonstrated a right subclavian arterial aneurysm associated with the aortic arch anomaly. Proximal and distal ligation of the subclavian arterial aneurysm and reconstruction of blood flow by an aorto-subclavian bypass using a 5 mm GORE-TEX prosthetic graft were performed through a standard median sternotomy incision with extension to the right supraclavicular space. The postoperative course was uneventful and he was discharged in 3 weeks. The literature of the subclavian arterial aneurysm was briefly reviewed.

Aneurysm↗
PubMed1990

[Recurrence of perilymphatic fistula].

Recurrence of the perilymphatic fistula is not rare and may be a tough problem for surgical treatment. This is because a graft is usually applied on the ruptured window(s) from the middle ear and therefore the perilymphatic pressure directly acts on the graft. The recurrence may be caused by a technical failure, use of an unsuitable graft material, poor postoperative bedrest, trauma, increased inner ear pressure, etc. In our clinic, the recurrence occurred in 7 of 48 cases surgically treated. Vertigo accompanied with spontaneous or positional nystagmus was seen in all 7 recurrent cases, while only 2 of them complained of worsening of the existing hearing loss. Re-operation was carried out in two patients. In the first case, closure of the round window by the previous operation was found incomplete, and the perilymph leaked through the gap around the graft. In the second case, closure of the round window was complete, but perilymph leaked from the oval window. In order to prevent the recurrence, the operation should be carefully performed by using strong and adhesive tissue as a graft material, applying a glue between the graft and the inner ear window(s), and keeping strict postoperative bedrest.

Adolescent↗
PubMed1990

[Transmission of changes in the external ear atmospheric pressure to the perilymph].

Using guinea pig, pressures in the external ear canal, in the middle ear and in the perilymph were registered simultaneously, while pressure was applied to the external ear canal using an impedance audiometer. In the first experiment, applied pressure was changed in the range from 200 mmH2O to -200 mmH2O with and without the opening of the otic bulla. The change in the perilymphatic pressure with the opening was smaller than that without the opening. The result indicates that the external ear pressure is transmitted to the perilymph not only via the ossicular chain but also via the middle ear cavity without the opening, while it is exclusively transmitted via the ossicular chain with the opening. Pressure transmission to the perilymph was significantly impaired either by disrupting the ossicular chain or by closing the round window niche, especially by the latter. Thus the middle ear cavity itself plays an important role in pressure transmission from the external ear canal to the perilymph mainly via the round window. In the second experiment, applied pressure to the external ear canal was changed in the range from 1000 mmH2O to -1000 mmH2O after the Eustachian tube being closed. Between 400 mmH2O and -200 mmH2O, the middle ear and perilymphatic pressures paralleled well with the applied pressure. Beyond these levels, the middle ear pressure increased or decreased in response to the applied pressure but the perilymphatic pressure reversed against the middle ear pressure. Communication between perilymph and cerebrospinal fluid via the cochlear aqueduct is thought to be a major factor causing this reversal which, in turn, aggravates pressure gradient between the middle ear and the perilymph.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[A case of rapidly developed constrictive pericarditis following acute non-specific pericarditis].

A case of constrictive pericarditis which developed within one month after the onset of acute pericarditis was presented. A 3-year-old boy was admitted to our hospital suffering from dyspnea. Pericardectomy was performed 3 weeks after the pericardial drainage. His echocardiograms revealed the progressive thickening of the pericardium, severely restricted ventricular motion in both systole and diastole and paradoxical motion of the interventricular septum. Echocardiography at close intervals is useful for making the diagnosis and decision of the surgical intervention of rapidly developed constrictive pericarditis.

Acute Disease↗
PubMed1989

Somatostatin receptors and the effect of somatostatin on histamine-stimulated adenylate cyclase activity in isolated gastric glands of guinea pigs.

To investigate the mechanism of the suppressive action of somatostatin on gastric acid secretion, we determined the somatostatin binding and adenylate cyclase activity on crude membrane fractions of isolated gastric glands of guinea pigs. The binding studies using 125I-Tyr11 somatostatin showed the presence of somatostatin receptors with a single high affinity on crude membrane fractions. The dissociation constant (KD) for somatostatin was 1.05 +/- 0.13 nM, and the number of binding sites (Bmax) was 6.98 +/- 1.27 fmol/mg protein (mean +/- SE, n = 6). The adenylate cyclase activity was increased by histamine, which was completely inhibited by 10(-3) M cimetidine. Somatostatin non-competitively suppressed the histamine-stimulated adenylate cyclase activity in the presence of guanosine 5'-triphosphate (GTP). These results suggest that somatostatin inhibits histamine-stimulated acid secretion through the inhibition of the adenylate cyclase system, via somatostatin receptor and guanine nucleotide binding protein, which is activated by GTP binding.

Adenylyl Cyclases↗
PubMed1989

Simple method for quantitation of cell-bound protein A on Staphylococcus aureus cells by means of hemagglutination with sheep erythrocytes differentially sensitized with rabbit antibody and its clinical application.

A simple method for quantitation of cell-bound protein A (SpA) on organisms of Staphylococcus aureus was successfully devised by using hemagglutination between staphylococcal organisms and a series of sheep erythrocyte suspensions sensitized with different amounts of anti sheep erythrocyte rabbit antiserum. The validity of the principle and the reproducibility of the method presented here were precisely analyzed and the details of the method are presented. The hemagglutination was quantitatively inhibited both by normal rabbit serum and by soluble SpA. Using the method presented here, 376 strains of S. aureus freshly isolated from clinical materials were subjected to SpA quantitation in cell-bound form. According to the results, there was an unexpected distribution profile in the amounts of cell-bound SpA among the clinical isolates, which showed a two-peak pattern. A possible usefulness of the method presented here in clinical investigations is briefly discussed also.

Animals↗
PubMed1989

[A case of leiomyosarcoma of the inferior vena cava].

Primary leiomyosarcoma of the inferior vena cava is rare and fatal. A 15-year-old female was admitted with the diagnosis of the right atrial myxoma associated with the Budd-Chiari syndrome. The tumor of the IVC was unresectable, although the right atrial tumor extended from the IVC was extirpated. Pathological examination of the tumor revealed a leiomyosarcoma. She was hemodynamically improved immediately after the operation. But she was expired due to the hepatic failure 9 days postoperatively. No autopsy was obtained. The literature regarding with leiomyosarcoma of the IVC was briefly reviewed.

Adolescent↗
PubMed1988

Simplified method for preparation of concentrated exoproteins produced by Staphylococcus aureus grown on surface of cellophane bag containing liquid medium.

A simplified method for preparation of concentrated exoproteins including protein A and alpha-toxin produced by Staphylococcus aureus was successfully devised. The concentrated proteins were obtained by cultivating S. aureus organisms on the surface of a liquid medium-containing cellophane bag enclosed in a sterilized glass flask. With the same amount of medium, the total amount of proteins obtained by the method presented here was identical with that obtained by conventional liquid culture. The concentration of proteins obtained by the method, however, was high enough to observe their distinct bands stained on polyacrylamide gel electrophoresis. This method was considered quite useful not only for large-scale cultivation for the purification of staphylococcal proteins but also for small-scale study using the proteins. The precise description of the method was presented and its possible usefulness was discussed.

Bacterial Toxins↗
PubMed1988

Effect of temperature on antibacterial activity of lidocaine to Staphylococcus aureus and Pseudomonas aeruginosa.

The effect of temperature on the antibacterial activity of lidocaine to Staphylococcus aureus and Pseudomonas aeruginosa was investigated in vitro. At 10 C at which S. aureus organisms do not grow and might be metabolically inactive, the antibacterial activity of lidocaine to S. aureus was not observed in a concentration of 1%, which was quite antibacterial to S. aureus at 37 C. On the other hand, at 40 C a conspicuously increased antibacterial activity to S. aureus of lidocaine was observed in a concentration of 0.25% which was not antibacterial to S. aureus organisms at 37 C. Similar results were obtained when P. aeruginosa organisms were examined in place of S. aureus, although P. aeruginosa was found to be less susceptible to lidocaine than S. aureus. The clinical significance of the thermal effect on the antibacterial activity of lidocaine was discussed in brief.

Drug Resistance, Microbial↗
PubMed1988

Luminol-dependent chemiluminescence in antibody-sensitized neutrophils stimulated with protein A-bearing staphylococci.

When mouse polymorphonuclear leukocytes (PMNs) sensitized with rabbit antibody to mouse Ehrlich ascites tumor cells were stimulated by Staphylococcus aureus Cowan I cells, a conspicuous luminol-dependent chemiluminescence was observed in the absence of opsonin. The profile of the chemiluminescence (CL) response evoked by staphylococcal cells from antibody-sensitized PMNs had two peaks. An initial peak, observed within 1 min after stimulation, was sharp and high and a second peak, observed about 5 min after stimulation, was low and extended. The CL response of antibody-sensitized PMNs stimulated by S. aureus Cowan I cells was dose-dependently blocked by preincubation with soluble SpA. Cells of a mutant derived from S. aureus Cowan I strain with trace amounts of cell-bound SpA failed to stimulate the antibody-sensitized PMNs to generate the CL response. The antibody-sensitized PMNs were found to phagocytize SpA-bearing S. aureus cells even in the absence of opsonic serum. These results suggest that the observation presented here might provide a useful tool for the investigation of CL response of PMNs.

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↗
PubMed1987

Effects of H2-receptor antagonists on 3H-cimetidine binding and histamine-stimulation of cellular cAMP in isolated guinea pig gastric glands.

3H-Cimetidine binding to plasma membranes of isolated guinea pig gastric glands was investigated, and the effects of five H2-receptor antagonists on 3H-cimetidine binding and histamine stimulation of cellular cAMP were compared. Of the five cations tested, Cu++ markedly increased specific 3H-cimetidine binding. 3H-Cimetidine had high affinity (Kd = 0.41 x 10(-6) M) and low affinity (Kd = 12.8 x 10(-6) M) binding sites. Cimetidine and etintidine were potent inhibitors of 3H-cimetidine binding, while famotidine, ranitidine and TZU-0460 were not. Histamine stimulation of cellular cAMP was competitively inhibited by H2-receptor antagonists yielding pA2 values of 6.41 for cimetidine, 6.82 for etintidine, 6.87 for ranitidine, 6.94 for TZU-0460 and 7.60 for famotidine. Because the KB value (log KB = -pA2) of 0.39 x 10(-6) M for cimetidine is close to the Kd value for the high affinity 3H-cimetidine binding site, it is presumed to represent a part of the H2-receptor, and the relative potency of etintidine against cimetidine in inhibiting 3H-cimetidine binding is similar to that in inhibiting histamine stimulation of cellular cAMP. These results suggest that imidazole-derived H2-receptor antagonists (cimetidine and etintidine) and non-imidazole H2-receptor antagonists (famotidine, ranitidine and TZU-0460) compete with histamine at different sites on the H2-receptor of the gastric glands.

Animals↗