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Biomedical subjects

Y Harada

Publications and source records attributed to Y Harada.

At least 631 records · Page 35Linked to original sources
PubMed1987

An experimental study demonstrating the physiological polarity of the frog's utricle.

The frog Rana nigromaculata was used as an experimental model. The utricle and its nerve were isolated with the anterior and the lateral semicircular canal ampullae in frog Ringer's solution. The utricular otoconia and the otoconial membrane were then carefully removed. The halved anterior canal cupula was next placed in the tip of a glass microelectrode, which was mounted on a micromanipulator. The cupula was placed in the center of either the medial or the lateral part of the macula and was moved toward or away from the striola along the axis vertical to the striola. When the medial part of the macula was stimulated, 5 micron of striolapetal cupular movement elicited an excitatory nerve discharge. When the lateral part of the macula was stimulated, the striolapetal stimulus likewise induced an excitatory response. These results indicate the existence of physiological polarity on the utricular macula.

Action Potentials↗
PubMed1987

Three-dimensional ultrastructure of the endolymphatic sac.

The subcellular structures of the epithelial cells of the guinea pig endolymphatic sac were studied. By using a newly developed scanning electron microscopy technique, the intracellular organelles could be studied three-dimensionally and the topographic relationships analyzed. The light epithelial cell has an extensive network of endoplasmic reticulum which is characteristically arranged in a baso-apical direction. The connections between the inner surface of the plasmalemma and the endoplasmic reticulum were observed, as were connections between the Golgi complex and the endoplasmic reticulum. Our findings support the hypothesis that the endoplasmic reticulum might form transcellular channels through which the cell can transport water and ions from the lumen of the endolymphatic sac out into the subepithelial tissue. The dark epithelial cells seen in particular contained the smooth type of endoplasmic reticulum. Lysosomes were also observed in the dark cells, indicating that these cells probably have more of a secretory function.

Animals↗
PubMed1987

Principle of a noninvasive method of measuring Max(dP/dt) of the left ventricle: theory and experiments.

In early systole, before the effects of reflected waves from the periphery become significant, the following equation applies: PA - PO = rho cu (1) where PA and PO are the instantaneous and end-diastolic pressures in the ascending aorta, rho the density of blood, c the velocity of the pulse wave in the aorta, and u the velocity of blood. Differentiation of Eq. (1) with respect to time t yields: dPA/dt = rho c(du/dt) (2) If there is no aortic stenosis, and if the pressure gradient due to the inertia of the blood during acceleration is neglected, the left ventricular pressure P is nearly equal to PA during the ejection period. Since both dP/dt and dPA/dt take their maximum values at times close to the time of aortic valve opening, the following equation applies: Max(dP/dt) not equal to Max(dPA/dt) (3) where Max signifies the maximum value of a derivative. Equation (2) reduces to: Max(dPA/dt) = rho c Max(du/dt) (4) Substitution of Eq. (4) into Eq. (3) yields: Max(dP/dt) not equal to rho c Max(du/dt) (5) Experiments were performed on seven dogs. Max(dP/dt), Max(du/dt), and c were measured during volume loading, pressure loading and unloading, and before and after administration of positive and negative inotropic agents. There was a good linear correlation (Y = 1.01X-2, r = 0.97) between Max(dP/dt) and rho c Max(du/dt). Therefore, Eq. (5) is a universal equation which holds, irrespective of the dogs and interventions employed to change the hemodynamic state.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Early adrenal infection by herpes simplex virus type-1 (Miyama + GC strain): special reference to inoculation dose and spread from the adrenal to the central nervous system.

Male C3H/HeN mice, aged 5 weeks, were inoculated intraperitoneally (i.p.) with different doses (1 x 10(3), 1 x 10(5), 5 x 10(5), 1 x 10(6) pfu) of the herpes simplex virus type-1 (HSV-1) (Miyama + GC strain). The LD50 of this virus was 10(2) pfu (i.p.) per mouse. All the mice in each group died 12 days after inoculation. Adrenal necrosis was found to be dose-dependent, the threshold dose being 5 x 10(5) pfu. In addition, encephalitis and inflammatory cell infiltration in abdominal ganglia appeared in 3-4 days after inoculation. By the plaque method, HSV-1 was detected first in the adrenal glands, then in neurons in the spinal cord and the brain. These findings suggest that in mice inoculated with doses of virus sufficient to infect the adrenal gland, HSV-1 spreads to the central nervous system through peripheral nerves after replication in the adrenal.

Adrenal Gland Diseases↗
PubMed1987

Simultaneous pleomorphic adenomas of the right parotid and ipsilateral submandibular glands.

A case of simultaneous pleomorphic adenomas of the right parotid and ipsilateral submandibular glands was reported. The patient was a 68-year-old woman who had a ten-year history of an otherwise asymptomatic non-enlarging mass in the parotid gland and a slowly enlarging mass in the submandibular gland. Microscopically, the parotid tumor consisted of predominant spindle-shaped cell proliferations with myxoid stroma in places. The submandibular gland tumor showed tubular and trabecular formations with stroma consisting of hyalinized fibrous connective tissues. Simultaneous pleomorphic adenomas in the salivary glands are so rare that only 23 cases can be found in the literature. Additionally, only five tumors occurring simultaneously in the parotid and submandibular glands are reported in the literature. Our case seems to be the sixth of simultaneous pleomorphic adenomas of the parotid and submandibular glands.

Adenoma↗
PubMed1987

Acoustic neuroma presenting with sudden and fluctuating hearing loss--a case report.

A case of acoustic neuroma presenting with sudden and fluctuating hearing loss is reported. The patient was a 38-year-old Japanese woman who noticed a sudden onset of hearing loss and tinnitus in the right ear. With a provisional diagnosis of sudden deafness, she was subjected to conservative therapy, including steroid hormone. The hearing started to recover and reached a normal level 2 months after the treatment. Meanwhile, the results of an ABR and plain skull X-rays aroused a suspicion of acoustic neuroma. She was operated on via a middle cranial fossa approach and an acoustic neuroma occupying the internal auditory meatus was removed.

Acute Disease↗
PubMed1987

Expression of two different tachykinin receptors in Xenopus oocytes by exogenous mRNAs.

Three tachykinins, substance P (SP), neurokinin A (NKA), and neurokinin B (NKB), have been isolated from the mammalian nervous system. In accordance with the presence of multiple tachykinins, the existence of multiple tachykinin receptors has been suggested. These receptors differ in binding specificities for different tachykinins. However, it is not known whether these receptors are indeed made of different molecules or whether the same receptor molecule undergoes posttranslational modification at different destination tissues, thereby altering its binding specificity. We examined whether mRNAs isolated from different tissues may synthesize different types of tachykinin receptors in the same expression system. For this purpose, Xenopus oocytes were injected with poly (A)+ RNAs extracted from rat brain or bovine stomach, and their responses to different tachykinins were examined under voltage-clamp. On the basis of potency ranking of 6 tachykinin agonists, the receptor induced by rat brain mRNA was found to correspond to a tachykinin receptor subtype currently classified as the NK-1 (SP-P) receptor, whereas that synthesized by bovine stomach mRNA corresponded to the NK-2 (NK-A) receptor. Thus, each of the 2 receptors can be induced in the same expression system, depending upon the source of exogenous mRNA injected. Therefore, the difference in the nature of the 2 receptors does not seem to be due to the possible posttranslational modification alone. However, the ionic mechanisms underlying activation of the 2 receptors translated in oocytes were similar. It is likely that activation of the 2 receptors uses the same internal mediator in oocytes.

Animals↗
PubMed1987

[Relation between prognosis and the Su-PS skin reaction in patients with non-resected primary lung cancer receiving OK-432].

Chemotherapy and administration of OK-432 were performed concomitantly in 49 cases of inoperable primary lung cancer, and the Su-PS skin reaction was measured. In the group of patients under 60 years of age, the maximum diameter of the reaction after chemotherapy tended to be large, and evaluation of the results showed that the maximum diameter tended to be large in the group showing tumor contraction effects. In a comparison of the prognosis between the group which survived for less than 6 months and that which survived for 6 months or longer, there was no significant difference between them before administration of OK-432, but when the maximum reaction diameter after chemotherapy was compared, that in the group which survived for 6 months or longer was significantly stronger (p less than 0.05). The Su-PS skin reaction at the time of administration of OK-432 is therefore considered to be a useful immunological parameter for predicting the results of treatment and also for prognosis.

Adenocarcinoma↗
PubMed1987

The morphological changes in the vestibular sensory epithelia following electrical stimulation.

The morphological changes of the vestibular sensory epithelia of the guinea pig following electrical stimulation were investigated using scanning electron microscope. Positive and negative square wave pulse stimulation was given through a silver ball electrode placed on the round window membrane for one hour. The current intensities used were 100, 200 and 300 microA. While the direct current stimulation at intensities of 100 or 200 microA did not cause any significant changes, severe damage of the utricular macula and the ampullar crista of the lateral semicircular canal was observed at 300 microA. The degenerative changes such as fusion of sensory hairs, protrusion of the cuticular plate and loss of sensory cells were found on both the utricle and the semicircular canal. In the most severely damaged area, the sensory epithelial surface was badly torn apart. In the clinical application of direct current to the inner ear for relieving tinnitus, special attention should be paid to the vestibular organ.

Acoustic Maculae↗
PubMed1987

Morphological changes in the vestibular epithelia and ganglion induced by ototoxic drug.

The morphological changes of the vestibular sensory epithelia and the vestibular ganglions induced by Gentamicin(GM) were investigated using scanning electron microscope, transmission electron microscope and light microscope. The guinea pigs were injected with a single application of 4 mg (0.1ml) of GM into the middle ear through the tympanic membrane. The vestibular organs and the ganglions were observed up to 6 months after the treatment. Four days after the injection, fused, ballooned and missing cilia were observed in the vestibular sensory epithelia. These changes progressed and extended toward the periphery of the crista and the macula. The changes of the vestibular ganglions were first observed one month after the treatment. The degenerative process started from destruction of the mitochondrial cristae and vacuolization of the cytoplasm in the Schwann cell. The next step of the change was dissociation of the myelin sheath around the ganglion cell. The cytoplasmic organelles in the ganglion cell gradually deteriorated. At the later stage, the myelin sheath around the ganglion cell disappeared and the number of the cell reduced. Furthermore, the myelin sheath of the nerve fiber was dissociated. In this study the signs of the vestibular ganglion damage were later than that of the vestibular organ. However, we thought the changes in the ganglion are probably due to direct influence of GM, since the degeneration was found to develop in a relatively short period.

Acoustic Maculae↗