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Biomedical subjects

Y Harada

Publications and source records attributed to Y Harada.

1,007 records · Page 56Linked to original sources
PubMedDate not supplied

Three-dimensional structures of the vestibular sensory epithelia.

Vestibular neurosensory epithelia of the guinea pig and the bull frog were investigated by scanning electron microscopy. The crista ampullaris or macula were freeze fractured followed by maceration with 0.1% OsO4 solution for 24-60 h (osmium-DMSO-osmium method). Following this, three-dimensional intracellular structures were observed. The mitochondria which exist in the nerve chalice surrounding the type I cell were various in shape, globular, long and slender. Golgi apparatus, endoplasmic reticulum and thin fibrous structures of the sensory cells or supporting cells were clearly demonstrated. Concerning nervous system, nerve fibre, afferent and efferent nerve endings, further synaptic structures were also observed stereoscopically.

Acoustic Maculae↗
PubMedDate not supplied

Electron-microscopic study of the vestibular dark cells in the crista ampullaris of the guinea pig.

The ultrastructure of the vestibular dark cells in the crista ampullaris of the guinea pig was observed using both transmission and scanning electron microscopy. The dark cells had numerous vacuoles of varying size and electron density, and also characteristic well-developed basal infoldings. These findings strongly suggest that the dark cells play an important role in fluid transport. Unique meshwork structures were observed on the luminal surface of the dark cells. Otoconia showing varying degree of degeneration were occasionally recognized on and near these structures. Electron microscopy revealed that the meshwork was comprised of cytoplasmic processes in a reticular arrangement. They seem to be engaged in the metabolism of otoconia, and perhaps also in fluid transport.

Animals↗
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A comparative study of the isolated anterior and posterior semicircular canals of the bull frog.

The anterior semicircular canals of bull frogs were isolated and the cupula was removed from the crista and the sensory cilia on the crista were depressed toward the canal side by a glass micropipette. Seven points on the crista were selected for stimulation. Decremental time constants of the anterior ampullary nerve action potentials were measured. The longer time constants were measured at the lateral points of stimulation which progressively shortened toward the central point. The overall values of the time constant were significantly shorter than those of the posterior semicircular canal. This indicates that the anterior semicircular canal has a larger number of phasic receptors than the posterior canal.

Action Potentials↗
PubMedDate not supplied

Intracellular changes in the endolymphatic sac after labyrinthectomy.

Intracellular changes within the lining epithelium of the murine endolymphatic sac were investigated following surgical labyrinthectomy. The light and the dark epithelial cells reacted differently. Some light cells showed altered morphology after labyrinthectomy. The smooth endoplasmic reticulum formed a tubular network in the apical cytoplasm which was contiguous with the extremely well developed rough endoplasmic reticulum. These light cells also contained numerous granules. Such cell modifications indicated a secretory potential in this type of light cells. The dark cells showed signs of increased activity, with an augmentation of endoplasmic reticulum and an increased electron density of the cytoplasm. The dark cells increased their luminal surface to such an extent that they frequently covered the luminal surface of neighbouring light cells. Our hypothesis is that the dark cells may, in some way, control the function of the light cells and in this way also the absorptive mechanisms of the endolymphatic sac.

Animals↗
PubMedDate not supplied

Sensory hair fusion and glycocalyx changes following gentamicin exposure in the guinea pig vestibular organs.

This study demonstrates the mechanism of sensory hair fusion and its relationship to glycocalyx on the hair cells in the vestibular epithelia of gentamicin-treated guinea pigs, using a ruthenium red staining technique. 0.1 ml of a solution containing 50 mg gentamicin sulphate per 1 ml was injected once into the middle ear. After 7 days, various stages of sensory hair degeneration were observed. The glycocalyx was clearly visualized by ruthenium red. The gentamicin-induced hair damage started with a local decrease in or loss of glycocalyx from neighbouring sensory hairs, followed by formation of local attachment areas of membrane sensory hairs. These findings suggest that the glycocalyx of the sensory cell may play an important role in separating the cilia as well as maintaining the organization of the bundle. Therefore, the decrease in or loss of glycocalyx from the hair bundle of sensory cells affected by gentamicin, either directly or secondarily, can be considered as closely related to the fusion of the sensory hairs.

Animals↗
PubMedDate not supplied

Three-dimensional observation of the spiral ganglion cell. Normal structure and pathological changes.

Spiral ganglia of guinea pig and mouse were investigated by scanning electron microscopy (SEM). The cochlea was freeze-fractured and then macerated with 0.1% OsO4 solution for 70-90 h (A-O-D-O method (1]. This allowed three-dimensional observation of the general view of the spiral ganglion and the intracellular structure. Two types of spiral ganglion cell, type I and type II, could be distinguished by the A-O-D-O method. Intracellular membranous structures such as mitochondria, endoplasmic reticulum (ER) and Golgi apparatus were also demonstrated stereoscopically. Furthermore, morphological changes in mouse spiral ganglion cells due to injection of Mycobacterium fortuitum were observed, using SEM. The degenerative process began as swelling of the mitochondria. When Schwann cell became affected, the myelin sheath disappeared and the ganglion cell border became indistinct. This degeneration developed rapidly, suggesting a direct influence of the bacteria on the ganglion cell. Various types of inclusion body with limiting membrane could be demonstrated stereoscopically. As Romand & Romand (4) suggested, these inclusion bodies may be remnants of cellular organellae or various type of lysosomes.

Animals↗
PubMedDate not supplied

A temperature-sensitive cardiac pacemaker.

An artificial cardiac pacemaker which is sensitive to the temperature of blood in the right atrium has been fabricated. For a temperature change of 20 degrees C the circuit achieves 90% of its final response within a period of 18 s. In the authors' opinion this is satisfactory since changes in blood temperature are generally small. Cardiac output in dogs rose from 2.37 +/- 0.65 to 4.54 +/- 1.15 l/min when the rate was increased from 202.6 beats/min(b.p.m.) at 37.6 degrees C to 231.6 b.p.m. at 41 degrees C. Cardiac output was found, from statistical observation, to be improved at temperatures over 39.6 degrees C.

Animals↗
PubMedDate not supplied

Microcomputer-based cardiac pacemaker-control system through blood temperature.

A microcomputer-based temperature-sensitive cardiac pacemaker system and some preliminary experiments are described. The system consists of a microcomputer, a twin 5 in floppy disk unit, expansion and interface units, a visual display unit and a printer. It senses the blood temperature in the right atrium, determines the pacing rate and supplies the heart with stimulating pulses. System-heart interfacing is performed by the separate pacing and sensing units which communicate with the computer via a peripheral interface IC in an expansion unit. The pacing rate is determined by software, rather than a combination of hardware elements. The temperature response time of the system, from 25 degrees C to 40 degrees C is about 26 s, and this would seem to be satisfactory given that smaller and slower changes in blood temperature are normal.

Animals↗
PubMedDate not supplied

Telemetry system for heart-rate and blood temperature using a microcomputer.

A radio-telemetry system using a microcomputer has been constructed to measure both the heart-rate (HR) and right atrial blood-temperature in dogs. The telemeter incorporates a thermistor temperature probe, which allows blood-temperature measurements in the range of 35 degrees-42 degrees C with an available resolution of +/- 0.02 degree C. The output of the receiver is connected to active filters, a frequency counter and an HR meter, and finally to a microcomputer, through an appropriate interface circuit, for data linearization and storage.

Animals↗
PubMedDate not supplied

A fuzzy approach to the rate control in an artificial cardiac pacemaker regulated by respiratory rate and temperature: a preliminary report.

Fuzzy theory was applied to the rate control of a cardiac pacemaker which uses two parameters, respiratory rate and temperature, as the parameters for rate regulation. Using 25 fuzzy reasoning rules derived from five mongrel dogs, the pacing rates in three animals were calculated and compared with the intrinsic heart rates. It is concluded that the fuzzy method is well suited for the rate determination of a multi-parameter rate-responsive cardiac pacemaker.

Algorithms↗
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A self-tuning effect of membership functions in a fuzzy-logic-based cardiac pacing system.

This paper describes a self-tuning method of membership functions in a fuzzy-logic-based cardiac pacing system and validates its feasibility in a double sensor system which has minute ventilation and oxygen saturation level as its guides for the rate regulation. Though the agreement between the pacing rates (fuzzy rates) calculated with three linguistic variables for each parameter and the target rates were not satisfactory, it was improved significantly by tuning the membership functions. Almost the same evaluated values with those obtained by using six linguistic variables for each parameter were obtained. Time required for the self-tuning process was about 40 s (386CPU, 20 MHz) which was fast enough for the system. The smaller number of linguistic labels results in a smaller number of rules, which is beneficial in implantable cardiac pacemakers with limited memory capacity. A fuzzy-logic-based cardiac pacing system is promising for the realization of custom-made cardiac pacemakers.

Exercise Test↗
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HPV33 DNA in premalignant and malignant breast lesions in Chinese and Japanese populations.

The relationship between human papillomavirus (HPV) infection and breast cancer is controversial. In this study, paraffin-embedded tissue blocks prepared from 72 patients with benign, premalignant or malignant mammary lesions were randomly collected from the Shanghai region of China and Tokushima in Japan. DNA specimens extracted from all tissues were amplified by the polymerase chain reaction (PCR) using HPV16, 18 and 33 primers. Southern blot hybridization showed 19 cases to be positive for HPV33 DNA: The positive rate for HPV33 DNA in Chinese (41.7%) was significantly higher than in Japanese (11.1%) (P < 0.01): The positive rate for HPV33 DNA in invasive ductal carcinoma (34.1%) was higher than in benign or borderline mammary lesions (5%) (P < 0.02). There were no statistically significant difference among the relationship of the nuclear grade of breast cancers with HPV33 DNA-positivity. This is the first report of a positive correlation between HPV33 DNA and breast lesions in Chinese and Japanese populations. These results suggest that the infection by HPV33, but not HPV 16 or HPV 18, may be involved in breast hyperplastic lesions, especially breast cancer, in humans.

Adult↗
PubMedDate not supplied

A novel "permanent" acid-type hair color made possible with dye-metal ion complex technology.

The advantages and disadvantages of oxidative permanent and acid-type semi-permanent hair colors are evident. The former provides a longlasting "permanent" color, while the latter imparts less damage to the hair. We developed a novel acid-type hair color technology that can allow an acid dye and a metal ion to form a complex inside the hair similar to the oxidative hair color. It is well known that acid dye diffuses into the hair and creates an ionic bond with the positively charged amino acid residues of hair protein. However, the dye can be extracted easily from the hair by daily shampooing due to the weakness of the bond. In order to strengthen this bond and to prevent the extraction of the dye by shampooing, an aluminum chloride ion was chosen as the metal ion component to form the dye-metal complex. A proper composition of penetration enhancers, benzyl alcohol and ethyl alcohol, was required to allow acid dyes to interact with the aluminum chloride ion after each component penetrates deeply into the hair to form a complex inside the hair. To provide color brightness and a color longevity effect to hair color, glycolic acid was also selected due to the observation that a weak acid with a small molecular weight would enhance those effects.

Acids↗
PubMedDate not supplied

Pharmacokinetic study of cimetidine in pediatric duodenal ulcer.

The subjects were five schoolboys aged 7 to 12 years with endoscopically proved duodenal ulcers. After the oral administration of 10 mg/kg of cimetidine, the mean peak cimetidine level was 2.86 microgram/ml; the time to peak level was 1.3 hours; the area under the concentration-time curve was 9.74 microgram/ml.hr; the elimination half-life was 1.55 hours; and 56% of the drug was excreted unchanged in the urine. The plasma cimetidine level remained above 1.0 microgram/ml for 3.4 hours and above 0.5 microgram/ml for 5.8 hours. Gastric pH was increased to 5 or above for three to six hours. These results are similar to those reported previously in other pediatric patients. After eight weeks of treatment with 20 mg/kg of cimetidine daily, the duodenal ulcers were completely healed in four of five patients studied.

Administration, Oral↗
PubMedDate not supplied

Three-dimensional observation of the cochlea. Intracellular structure of the hair cell and the supporting cell.

Intracellular structures of the guinea pig cochlea were observed by scanning electron-microscopy. The cochlea was freeze-fractured and then macerated with 0.1% OsO4 solution (aldehyde-osmium-DMSO-osmium (AODO) method). Intracellular organelles, such as mitochondria, endoplasmic reticulum (ER), and Golgi apparatus, were demonstrated stereoscopically. The ER of the outer hair cell showed the most interesting features, such as subsurface cisternae and lamellar body. The subsurface cisternae which formed a stratiform network covered the inner surface of the cell membrane of the supranuclear part. Variously shaped mitochondria were found on the innermost layer of the subsurface cisternae. The lamellar body consisted of dilated cisternae and tubules of ER. The tubular ER of the lamellar body were contiguous with the subsurface cisternae. The pillar cells, Deiters' cells and Hensen's cells had well-developed tubular ER, while Claudius' cells had poorly developed tubular ER.

Animals↗
PubMedDate not supplied

A new method for continuous measurement of platelet adhesion under flow conditions.

Platelet adhesion to the subendothelial tissue or biomaterial surface is an initial step in the formation of the hemostatic plug or thrombus. To clarify the mechanism of platelet adhesion in vivo, a simple and reproducible method for quantitation of platelet adhesion under flow conditions is required. In this study, a mechanical device for continuous recording of platelet adhesion under flow conditions using a quartz crystal microbalance was developed, an extremely sensitive sensor capable of measuring mass changes in the nanogram range. The relationship between surface mass change (delta W) and resonant frequency change (delta f) for pie-zoelectric crystals is given by the Sauerbrey equation: delta f = -fo2 delta W/NA pi (fo; fundamental frequency (5MHz) A; the area of quartz plate undergoing oscillation N; frequency constant for AT-cut quartz crystal pi; density of quartz crystal). Although the perfusion of buffer solution alone or addition of washed red cell suspension (Ht 30%) and formaldehyde-fixed platelets have no effect on delta f, addition of washed platelets in the presence of red cells caused an increase in delta f. To confirm that the increase in delta f results from platelet adhesion to the material surface, adherent and subsequently aggregated platelets were visualized by fluorescence microscopy using fluorescein-isothiocyanate labeled antiplatelet membrane glycoprotein Ib monoclonal antibody. There was a good correlation between the increase in delta f and the extent of platelet adhesion and subsequent aggregation.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Flow Velocity↗