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Biomedical subjects

H Inomata

Publications and source records attributed to H Inomata.

At least 181 records · Page 10Linked to original sources
PubMed1985

Actions of Ba++ on ionic currents of the guinea-pig taenia coli.

The actions of Ba++ have been studied on short segments of the guinea-pig taenia coli voltage-clamped by a double sucrose-gap method. Ba++ slows the rising phase of the action potential, increases the peak amplitude and delays the repolarization with a long plateau. Ba++ carries charges through the normally Ca++ channel and directly influences both the magnitude (Ia) and the reversal potential (Ea) of the early current. The activation is slowed slightly, but the inactivation is slowed markedly. The voltage-conductance relation is shifted toward more negative voltages in Ba++, and the maximum conductance, ga, is increased significantly. Ba++ displaces the late outward current toward more positive voltages. The voltage-conductance relation is shifted by some 20 mV in 2.5 mM, and increasingly larger amounts with increasing [Ba++]o. The maximum conductance, gb, and the reversal potential (Eb) are not altered. Co++ blocks the inward Ba++ current and reverses the effects of Ba++ on the potassium conductance. Ca++ competes with Ba++. The apparent Kd for Ba++ is 6 mM and the apparent Kd for Ca++ is 0.6 to 1.0 mM. When Ca++ is added, the plateau of the long action potential in Ba++ is shortened by one-half. The effects of Ba++ are ascribed to some screening effect on fixed negative charges on the inside and outside surfaces of the membrane.

Action Potentials↗
PubMed1984

Developmental immaturity of the trabecular meshwork in juvenile glaucoma.

We used light and electron microscopy to compare ten specimens of anterior chamber angle tissue obtained by trabeculectomy from seven patients with juvenile glaucoma (primary glaucoma with open iridocorneal angle in young humans with specimens of normal trabecular meshwork from humans of the same ages. In all cases of juvenile glaucoma, we observed a thick compact tissue consisting of cells with fine processes and extracellular substances at the anterior chamber side of Schlemm's canal and abnormal deposits of ground substances in the thick tissue. These observations strongly suggest that the thick compact tissue represents an immature development of the trabecular meshwork and may be one of the primary causes of increased intraocular pressure in juvenile glaucoma. Our studies indicate that both congenital and juvenile glaucoma occur because of developmental immaturity of the trabecular meshwork in anterior chamber angle tissue and that the more extensive the immaturity, the earlier the glaucoma will become manifest.

Adolescent↗
PubMed1984

The thyroid reserve in children with chronic lymphocytic thyroiditis revealed by the thyrotropin-releasing hormone and thyroid-stimulating hormone tests.

Serum thyroid hormone and TSH concentrations were measured before and after the administration of TRH (10 micrograms/kg body weight) and bovine TSH (10 IU) in 14 children with chronic lymphocytic thyroiditis. The TRH test showed that the responsiveness of TSH was positively correlated with the basal TSH (P less than 0.001) and inversely with the increase in serum thyroid hormones, for delta T3 (P less than 0.05) and for delta T4 (P less than 0.001). Overall, the patients had significantly lower mean values for basal T4, but not for T3. The TSH test revealed that the delta T3 was positively correlated with delta T4 (P less than 0.05). delta T3 after TSH administration was positively correlated with it after TRH (P less than 0.05). The patients were divided into three groups on the basis of their peak TSH values after TRH administration. In Group 1 (peak value below 40 microU/ml; N = 5); T3 increased significantly after TRH and TSH administrations (P less than 0.05 and P less than 0.025, respectively). In addition, delta T4 was significant after TSH administration. In Group 2 (peak TSH above 40 and less than 100 microU/ml; N = 6); only delta T3 after TRH was significant (P less than 0.05). In Group 3 (peak TSH above 100 microU/ml; N = 3); the response of thyroid hormones was blunted. Thus, the thyroid hormone responses to endogenous TSH coincided with that to exogenous TSH, and the exaggerated TSH response to TRH indicates decreased thyroid reserve.

Adolescent↗
PubMed1984

Requirements of external Ca and Na for the electrical and mechanical responses to noradrenaline in the smooth muscle of guinea-pig vas deferens.

Noradrenaline (NA) evoked a contraction which consisted of two components, an initial one associated with only depolarization and a second one with spike discharges. Both contractions were abolished in a Ca-free solution leaving only small depolarization. In a Na-free solution, the initial contraction was increased in keeping with the short term depolarization, while the second contraction was abolished. It is suggested that NA initially causes Ca influx which secondarily increases Na permeability.

Animals↗
PubMed1984

Electrical and mechanical events through activation of muscarinic receptor in the smooth muscle of guinea-pig vas deferens.

Electrical and mechanical responses of the guinea-pig vas deferens to exogenous acetylcholine (ACh) were observed by means of a single sucrose-gap method. ACh at various concentrations evoked a contraction consisting of two components. The initial component seemed to be independent of a depolarization, while the second one was dependent on it. All ACh responses were abolished by Ca removal from the external solution. The results suggest the existence of a pathway by which ACh even at low concentrations causes a Ca influx without potential changes.

Acetylcholine↗
PubMed1984

Anterior and posterior parts of human trabecular meshwork.

From gonioscopic observations, the trabecular meshwork was tentatively divided into anterior and posterior parts. The anterior part was defined as the zone from the Schwalbe's line to the anterior edge of the Schlemm's canal, and the posterior part was from the anterior edge of the Schlemm's canal to the angle recess. The patients' own blood cells were injected into the anterior chamber of two eyes about to be enucleated due to malignant tumors, and cell distribution in the trabecular meshwork was examined histologically. Blood cells in the posterior part of the trabecular meshwork were numerous, particularly in the area adjacent to the Schlemm's canal and anterior to the ciliary muscle at the angle recess, yet only a few cells were seen in the anterior part. At the angle recess, the blood cells accumulated in the perivascular connective tissue of the major arterial circle of the iris. These observations suggest that the posterior part of the trabecular meshwork is the most important for aqueous humor drainage in the human eye, both with regard to the conventional and unconventional routes, while the anterior part plays a lesser role in the aqueous outflow. It is also suggested that some proportion of the aqueous humor entering the tissues at the angle recess may flow through the perivascular tissue of the major arterial circle of the iris.

Aged↗
PubMed1983

Significant fluctuation of thyroid function in children with chronic lymphocytic thyroiditis.

In order to investigate the degree of pituitary reserve of TSH secretion and the fluctuation of thyroid function in children with chronic lymphocytic thyroiditis, TSH response to TRH was examined in 42 patients, and the thyroid function was carefully followed up in two patients retrospectively and in four prospectively. Increased basal TSH levels were revealed in seven patients (16.8%), and an exaggerated response of TSH to TRH loading in 15 (35.8%). We retrospectively observed spontaneous recovery of thyroid function in two cases. In one of them, two episodes of a transient decrease in thyroid function over a period of several years were noted. Prospectively, low normal T4, elevated TSH and normal T3 were detected in two cases at the first visit. Thereafter, TSH levels decreased to the normal range and the exaggerated response of TSH to TRH became normal. In two other cases, typical transient hypothyroidism occurred during the observation period. These fluctuations lasted for only a few months, and concomitant changes in the size of the thyroid gland were observed. No signs or symptoms suggesting viral infection were noted during the study period. Nor were changes in titers of thyroid auto-antibodies detected. These results show that the secretion of TSH is exaggerated and the thyroid function is decreased in adolescents with chronic lymphocytic thyroiditis, but the thyroid function may fluctuate from euthyroid to hypothyroid within a short period. The causes of these changes, especially of the transient hypothyroidism remain to be classified.

Adolescent↗
PubMed1983

Effect of cobalt on electrical and mechanical responses to exogenous noradrenaline and to field stimulations in the guinea-pig vas deferens.

Co2+ suppressed the mechanical responses evoked by field stimulations and by application of noradrenaline (NA) in the smooth muscle of guinea-pig vas deferens. However, the membrane excitation and force development evoked by depolarizing currents were not much affected in the Co2+ treatment. It is proposed that Co2+ suppresses NA induced contraction by inhibiting the development of the membrane depolarization.

Action Potentials↗
PubMed1983

Choroidal neovascularization in long-standing case of Vogt-Koyanagi-Harada disease.

The eyes in a case of Vogt-Koyanagi-Harada disease (VKH) with long-standing uveitis for 26 years after the onset were studied histopathologically. It was found that typical granulomatous inflammation was persistent in the uveal tract and the choroidal neovascularization occurred in the peripheral fundus accompanied by proliferation of the retinal pigment epithelial cells (RPE). Some of the new vessels under the pigment epithelium extended into the vitreous. It was concluded that the ocular inflammation of VKH was essentially granulomatous even in this long-standing case. Disappearance of choroidal melanocytes, existence of epithelioid cells containing pigment granules, and accumulation of lymphocytes and plasma cells in the lesion indicated that the inflammation was an autoimmune reaction against uveal melanocytes, although the trigger initiating the disease remains unknown. It was further concluded that the peripheral fundus as well as the peripapillary and macular areas was a predilected site for choroidal neovascularization in chronic uveitis. The choroidal neovascularization may develop in such a way that the uveal inflammation damages the Bruch's membrane and choriocapillaris and consequently causes retinal ischemia, thus stimulating the endothelium of the choriocapillaris and the overlying RPE to proliferate. There is a close relation between choroidal neovascularization and proliferation of RPE. Choroidal neovascularization may cause reactive proliferation of the RPE and vice versa.

Choroid↗
PubMed1983

Ocular manifestations of congenital muscular dystrophy (Fukuyama type).

Ocular manifestations in two cases of congenital muscular dystrophy of Fukuyama type were reported. This disease is characterized by early onset of hypotonia, generalized muscle weakness and atrophy, mental retardation, and elevated serum creatine-phosphokinase activity. The symptoms include entropion of lower lids, pathological myopia with astigmatism, optic nerve pallor, and irregular grayish subretinal mottling. Case 1 showed additional features of posterior staphyloma, dragged papillomacular vessels, peripheral grayish-white discoloration of the retina, and rete mirabile as well as abnormal vascular anastomosis.

Astigmatism↗