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Biomedical subjects

M Sakagami

Publications and source records attributed to M Sakagami.

At least 109 records · Page 6Linked to original sources
PubMed1991

Transport of HRP through Reissner's membrane in experimental endolymphatic hydrops.

Unilateral endolymphatic hydrops was produced in guinea pigs by cauterization of the endolymphatic sac. Measurements of compound action potential (CAP), cochlear microphonics (CM) and negative summating potential (-SP) confirmed endolymphatic hydrops three months after surgery. In both control and hydropic ears, reaction product of HRP was observed only on the perilymphatic surface of the epithelial cells of Reissner's membrane after 10 min perfusion, while it was observed on both the endolymphatic and perilymphatic surfaces after 30 min perfusion. Epithelial tight junctions were not stained and labelled pinocytotic vesicles were observed in the epithelial cells. These findings suggest that the transport of HRP through Reissner's membrane is unchanged in endolymphatic hydrops and that the epithelial junctions are tight regardless of the distension of Reissner's membrane.

Animals↗
PubMed1991

Histopathology of the temporal bones in thanatophoric dysplasia.

The pathological findings of temporal bone in two cases of thanatophoric dysplasia were reported. Thanatophoric dysplasia is classified into type 1 and type 2, each of which has been reported to show specific clinical and radiographic-findings. The present study revealed that each type also showed specific characteristic in the structure of the temporal bones. The developmental mechanisms of hearing impairment in this disease were also discussed on the basis of the pertinent literature.

Autopsy↗
PubMed1990

Permeability of the round window membrane to middle-sized molecules in purulent otitis media.

The effect of pneumococcal otitis media on the permeability of the round window membrane was evaluated using tetraethylammonium ions as a tracer. Round window membrane permeability is reduced significantly at resolved stages of purulent otitis media. In contrast, measurements of round window membrane permeability indicate that acute purulent otitis media has a tendency to facilitate such permeability. Moreover, histologic observations of the round window membrane following bacterial inoculation further support the evidence of functional changes in round window membrane permeability. These findings indicate that the round window membrane in resolved stages of purulent otitis media plays a protective role in preventing the penetration of harmful substances into the inner ear.

Animals↗
PubMed1990

Uptake of horseradish peroxidase by the middle ear mucosa in experimentally induced otitis media.

Electron microscopy was used to study the characteristics of uptake of the protein tracer, horseradish peroxidase (HRP), by the middle ear mucosa of chinchillas. Two types of experimental otitis media were used: serous otitis media (SOM) produced by eustachian tube obstruction and purulent otitis media (POM) produced by inoculation of Streptococcus pneumoniae type 7F. HRP was placed in each tympanic bulla for either 1 min or 10 min. In the 1-min installation of HRP, the degree of HRP uptake was higher in SOM and POM animals than in control animals. Following the 10-min installation of HRP, the degree of HRP uptake was higher in SOM and POM animals than in control animals. Following the 10-min installation of HRP, the degree of tracer uptake was almost the same as among the control, SOM and POM animals. The mechanism of uptake was pinocytosis. In another experiment, 5-hydroxydopamine (mol. wt. 256) was used as a small tracer placed into the bulla to examine the permeability of epithelial tight junctions. No labelling of reaction product was observed in the tight junctions of the control, SOM or POM animals. These findings suggest that otitis media increases the uptake of HRP by pinocytosis and that epithelial tight junctions remain intact in inflammation of the middle ear cavity.

Animals↗
PubMed1990

Relationship between results of electrocochleography and caloric test in Menière's disease.

The relationship between an increase in the negative summating potential (-SP) and the results of caloric tests was examined in 35 patients with unilateral Menière's disease. The -SP was recorded by extratympanic electrocochleography. The quantitative bithermal caloric test was performed by irrigating with cool (30 degrees C) and hot (44 degrees C) water. An increased -SP was recorded in 20 of 35 patients (57%). Abnormal unilateral weakness (UW) on the involved side and abnormal directional preponderance (DP) to the involved side were observed in 16 of 35 (46%) and in 4 of 35 patients (11%), respectively. No significant correlation was found between an increased -SP and an abnormal UW and DP in Menière's disease.

Audiometry, Evoked Response↗
PubMed1990

Morphologic and biochemical study of vascular permeability of the middle ear mucosa in experimental otitis media.

The vascular permeability of the middle ear mucosa of chinchillas was examined by light and electron microscopy using horseradish peroxidase (HRP). Two kinds of experimental otitis media were used: serous otitis media (SOM) produced by eustachian tube obstruction and purulent otitis media (POM) produced by inoculation with Streptococcus pneumoniae type 7F. Normal mucosa showed no leakage of HRP. In SOM, vessels were dilated and tortuous, but they did not show HRP leakage. In POM, vessel leakage of HRP was extensive. Biochemically, we measured the middle ear effusion-to-serum ratio of both albumin and alpha 2-macroglobulin by an immunodiffusion method. The ratios of the two marker proteins for vascular permeability were significantly higher in POM than in SOM. This suggests that POM increases vascular permeability to a higher degree than SOM, and morphologic findings in the middle ear mucosa correlate with the biochemical composition of the middle ear effusion.

Albumins↗
PubMed1990

Sphingolipids and glycerolipids. I. Chemical structures and ionophoretic activities of soya-cerebrosides I and II from soybean.

Two glycosphingolipids named soya-cerebrosides I and II were isolated from soybean, the seeds of Glycine max Merrill (Leguminosae), and their chemical structures have been elucidated on the basis of physicochemical evidence and several chemical degradation reactions. By using a newly constructed liquid membrane-type apparatus (W-08) for measurement of ion-transport and ion-binding activities and by employing a method using human erythrocyte membranes for measurement of ion-permeability, it has been found that soya-cerebroside II exhibits ionophoretic activity for Ca2+ ion.

Cerebrosides↗
PubMed1989

[Studies on the method of sterilization with ethylene oxide gas. 2. Residual EO gas on sterilized objects].

Ethylene oxide gas (EO gas) adsorbed onto sterilized objects was quantitated in an effort to take a safety measure against residual EO gas following its use in sterilization. We measured residual amounts of EO gas adsorbed onto laboratory wares, small medical tools and appliances just after post-sterilization airation to examine whether they were rendered entirely free from EO gas by the process. The results led us to arrive at the following conclusions: 1. EO gas was recognized to remain on sterilized objects even after allowing them to stand for about 16 hours following airation. 2. The amount of residual EO gas was smaller on metallic products and larger on rubber products (notably rubber gloves). An exceedingly high concentration of EO gas was noted to remain on a tooth-brush, among other plastic materials. These facts seem to indicate that the amount of residual EO gas is closely related to the texture and shape of materials to be sterilized. 3. As regards the potential toxicity of residual EO gas. However, their sensitivity was proved to be questionable, judgment on a result being subject to considerable individual variations. 4. Nevertheless, it is incontestable that these devices can at least provide a rough estimate of unavailing since monitoring by direct measurement of residual EO gas is virtually infeasible from a practical point of view.

Dental Instruments↗
PubMed1988

The relationship of SP and AP findings to hearing level in Menière's disease.

The relationship of summating potential (SP) and action potential (AP) to hearing threshold level was examined in 46 patients with a unilateral Ménière's disease. The SP and AP were recorded with the extratympanic method. The ratio of -SP and AP amplitudes in affected ears to those in contralateral ears (-SP and AP amplitude ratio) at 80 dB nHL of click stimuli was used as parameters of analysis in order to diminish the variability of SP and AP amplitudes among individuals. The results revealed that there is no relationship between -SP amplitude ratio and the hearing threshold level at any frequency, whereas AP amplitude ratio has a significant negative correlation (r = -0.419, p less than 0.01) to the average hearing threshold level at 2-8 kHz, but not at 0.25-1 kHz (p greater than 0.05). The results indicate that an increase in the ratio of -SP amplitude to AP amplitude with the deterioration of the hearing at higher frequencies reported by our previous study (Mori et al., 1987) results from a decrease in AP amplitude rather than an increase in -SP amplitude. The dependence of AP amplitude on hearing threshold level and the independence of -SP amplitude on hearing threshold level suggests that the mechanism underlying the increase in -SP amplitude may be different from that causing the hearing loss in Ménière's disease.

Acoustic Stimulation↗
PubMed1987

[A case of a male gastric choriocarcinoma with massive mesenteric tumor and review of the literature on male choriocarcinoma].

A 32-year-old man was admitted to our hospital, complaining of an abdominal mass. An operation disclosed a large tumor, the size of a child's head, in the mesenterium of the transverse colon, with a multiple liver metastasis. A tumor resection was performed and, histologically, the tumor was diagnosed as being a choriocarcinoma. Gynecomastia was not observed. The patient died 2 months after this operation in spite of chemotherapy. An autopsy disclosed metastatic choriocarcinomas in the lungs, the liver, the peritoneum, the stomach, the adrenal glands and in the lymph nodes. The testis was found to be normal by a serial histological examination. Primary advanced adenocarcinoma, which is histologically similar to a choriocarcinoma, was found in the stomach. This case was finally diagnosed as being a gastric adenocarcinoma which showed choriocarcinomatous differentiation at various metastatic sites.

Adenocarcinoma↗
PubMed1987

Comparison of summating potential in Menière's disease between trans- and extratympanic electrocochleography.

The summating potential (SP) recorded concurrently with transtympanic (TT) and extratympanic (ET) electrocochleography in Menière ears was compared with respect to polarity and amplitude. There was a difference in SP polarity and amplitude between the two methods. The incidence of the increase in the ratio of -SP amplitude to the amplitude of the auditory nerve action potential (AP) (-SP/AP ratio) at 80 dB nHL as a response to a click was higher with the ET than with the TT method. Most of the ears exhibiting an increased +SP/AP ratio with the TT method showed an increased -SP/AP ratio with the ET method. The incidence of increased SP/AP ratios including -SP/AP and +SP/AP ratios was similar with both methods. A +SP was recorded in 14 of 25 ears upon stimulation with an 8-kHz tone burst with the TT method, whereas no +SP was recorded in 25 ears with the ET method. Tone bursts of 1 and 2 kHz produced a -SP and similar waveforms with both methods. Comparison of -SP amplitude recorded with both methods revealed that the ratio of -SP amplitude with both methods is different across the stimulus frequencies. The present study suggests that the -SP elicited by tone bursts of mid to low frequencies is more stable in the diagnosis of Menière's disease than -SP elicited by a click because of the lesser influence of the electrode location and that the increase in the +SP recorded with the TT method may be of clinical significance in the diagnosis of Menière's disease.

Action Potentials↗
PubMed1984

Ultrastructural study of the effect of acute hyper- and hypotension on the stria vascularis and spiral ligament.

The effects of acute hyper- and hypotension on the stria vascularis and spiral ligament of the rat were studied electron microscopically with the horseradish peroxidase (HRP) tracer method. Acute hypertension was induced by i.v. infusion of methoxamine chloride (Mexan), and acute hypotension by i.v. infusion of a ganglion-blocker (Arfonad) and by venesection. In both acute hyper- and hypotensive experiments, a large amount of leaked HRP spread into the intercellular spaces until it was stopped by tight junctions bordering the stria vascularis. The stria capillary endothelium displayed a dense distribution of labelled vesicles, which suggests increased vesicular transport. There was no extravasation of HRP from capillaries in the spiral ligament, despite the presence of some labelled pinocytotic vesicles. The present paper deals with the discovery of enhanced capillary permeability of the stria vascularis under acute hyper- and hypotension, and makes comparison between acute hyper- and hypotension in order to define the function of the stria vascularis.

Animals↗
PubMed1982

Fine structure and permeability of capillaries in the stria vascularis and spiral ligament of the inner ear of the guinea pig.

The blood capillaries in the stria vascularis and the spiral ligaments of guinea pigs were studied by electron microscopy with freeze-fracture and thin section methods, including tracer experiments with horseradish peroxidase (HRP) and microperoxidase (MP). The endothelial cells of the capillaries of both tissues are connected by tight junctions, and contain about the same number of micropinocytotic vesicles. In cases of intravascular administration before fixation, both of the tracers stained the perivascular space and almost all endothelial vesicles in the stria vascularis. On the other hand, the perivascular space and many vesicles in the spinal ligament were unstained. The endothelial tight junctions in the stria vascularis prevented the penetration of HRP, but sometimes allowed the penetration of MP. Those of the spiral ligament were impermeable to both tracers. In cases of tracer administration after fixation, leakage spots of HRP from capillaries were sparsely located all over the stria vascularis. Transendothelial channels and isolated fenestrae formed by micropinocytotic vesicles were detected. It is concluded that the capillaries of the stria vascularis are similar to the muscle capillaries and to the capillaries of the elasmobranch brain, whereas those in the spiral ligament are similar to the brain capillaries of higher vertebrates.

Animals↗