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Biomedical subjects

A Ohira

Publications and source records attributed to A Ohira.

At least 55 records · Page 3Linked to original sources
PubMed1994

[Sympathetic ophthalmia in an elderly man].

A 78-years-old man suffered from sympathetic ophthalmia. He had been treated with 5-fluorouracil (5-FU) for metastasis of colon cancer in the liver. He received a perforating eye injury in the left eye thereafter the eye became phthisic. Two months after the injury, he noticed visual disturbance in the right eye. He was treated with large doses of systemic corticosteroid after a diagnosis of uveitis of the right eye, but the visual acuity of the right eye became worse. The eye showed non-specific diffuse uveitis. A diagnosis of sympathetic ophthalmia was made from previous history and ocular findings. We enucleated the injured eye and continued the systemic corticosteroid. Then the right eye improved. Histopathological examination of the enucleated eye revealed the choroid was infiltrated with a granulomatous lesion of lymphocytes and epithelioid cells. HLA typing showed DR4, DR8, DR52, DR53, and DQ1, and we made a final diagnosis of sympathetic ophthalmia. It is probable that the clinical findings were modified by the 5-FU treatment and the patient's advanced age.

Aged↗
PubMed1994

Mitochondrial induction of adult T cell leukemia derived factor (ADF/hTx) after oxidative stresses in retinal pigment epithelial cells.

PURPOSE: Adult T cell leukemia derived factor (ADF) is a human homologue of thioredoxin (hTx), which exhibits scavenging activity with reactive oxygen intermediates. In their previous study, the authors found that after transient retinal ischemia, the expression of thioredoxin in rat retinal pigment epithelium (RPE) layer increased markedly. The present investigation is to determine intracellular ADF localization in RPE after transient ischemia and in cultured human RPE cells after oxidative insult by H2O2. METHODS: The authors employed immunoelectron microscopy to examine ADF localization in RPE. Labeling density analysis was performed to supplement the main observation in the experiment of transient retinal ischemia. 3-(4,5-dimethylthiazol-2yl)-2-5-diphenyltetrazolium bromide (MTT) assay was performed to verify the protective role of recombinant ADF (rADF) against H2O2. RESULTS: In immunogold electron microscopy, sparse ADF-positive labeling was seen in the cytosol and mitochondria in normal rat RPE and in untreated cultured RPE cells. After oxidative stress, it was concentrated in mitochondria in both groups. MTT assay proved that rADF protected cultured RPE from the toxicity of H2O2. CONCLUSIONS: This study shows the induction of ADF/hTx in mitochondria of RPE after oxidative stresses and its protective effect on cultured RPE exposed to H2O2. The data indicate the possibly important role of ADF/hTx in the protection of retinal cells from the oxidative stresses associated with retinal ischemic disease and probably with regular visual activity.

Adult↗
PubMed1993

CELSS nutrition system utilizing snails.

At the 40th IAF Congress in Malaga, a nutrition system for a lunar base CELSS was presented. A lunar base with a total of eight crew members was envisaged. In this paper, four species of plants--rice, soybean, lettuce and strawberry--were introduced to the system. These plants were sufficient to satisfy fundamental nutritional needs of the crew members. The supply of nutrition from plants and the human nutritional requirements could almost be balanced. Our study revealed that the necessary plant cultivation area per crew member would be nearly 40 m3 in the lunar base. The sources of nutrition considered in the study were energy, sugar, fat, amino acids, inorganic salt and vitamins; however, calcium, vitamin B2, vitamin A and sodium were found to be lacking. Therefore, a subsystem to supply these elements is of considerable value. In this paper, we report on a study for breeding snails and utilizing meat as food. Nutrients supplied from snails are shown to compensate for the above mentioned lacking elements. We evaluate the snail breeder and the associated food supply system as a subsystem of closed ecological life support system.

Animals↗
PubMed1992

Evidence that hepatocytes can phagocytize exogenous substances.

Although the phagocytic action of Kupffer cells is well known, such a phenomenon has not been well documented for hepatocytes. Following the injection of a suspension of egg lecithin-coated silicon particles (0.5-1.5 microns in diameter) into the portal vein of rats, Kupffer cells showed minimal phagocytotic action, which was in contrast to the hepatocytes which displayed numerous phagocytized silicon particles. By comparison, when noncoated silicon particles of the same diameter as those that were coated were injected into the portal vein, the opposite observation was made. There was no uniformity in the ability of the hepatocytes to phagocytize either coated or noncoated particles from one lobule to another. Some showed active phagocytosis, while in others no evidence of such a process was observed. These data provide strong evidence for the selective phagocytic action of liver hepatocytes.

Animals↗
PubMed1991

Long-term histologic and electrophysiologic evaluation of the alloy retinal tack.

The retinal tack is a useful adjunctive instrument in the repair of complicated retinal detachments. To examine the tissue response of chronically implanted alloy tacks, we implanted a series of tacks into rabbit eyes. Their effects were observed at 1 and 4 weeks, at 6 months, and at 2.5 years after insertion. Our observations indicate that the histology and electrophysiology of the retina was generally not affected. All tacks were surrounded by connective and/or glial tissue scar and induced firm retinal adherence. The retinal architecture was normal within 1 mm of the scar, indicating that these alloy tacks do not cause tissue damage outside the immediate area of the wound, even when left in place over a period of 2 years.

Alloys↗
PubMed1991

Experimental retinal tolerance to emulsified silicone oil.

Vitreous replacement by silicone oil has become increasingly popular in the treatment of severe and complicated retinal detachment. Several studies have suggested that silicone oil may be toxic to the retina or may stimulate periretinal proliferation. To better understand its effects, emulsified or nonemulsified silicone oil was injected into rabbit eyes that had undergone mechanical vitrectomy. Silicone oil was labeled with phthalocyanine blue to aid in histologic localization. Retinal changes were compared by light microscopy at 1, 4, and 12 weeks after intraocular injection. Emulsified silicone oil was found to penetrate the inner retina at 1 week and cause epiretinal membrane formation as early as 4 weeks after injection. Nonemulsified oil produced no histologic changes in the retina. No cytotoxic effects were observed in eyes treated with ether emulsified or nonemulsified silicone oil. It is concluded that emulsified silicone oil can both penetrate the retina and stimulate epiretinal membrane formation in the vitrectomized rabbit eye.

Animals↗
PubMed1990

Retinal ischemia and cell proliferation in the rat: the role of soluble mitogens.

Temporary retinal ischemia in the rat leads to a proliferation of endothelial cells and glial cells. We tested the hypothesis that this proliferation is caused by a release of soluble mitogens from the ischemic retina. Conditioned media were prepared from normal rat retina and from retina that had undergone 2 h ischemia and 48 h reperfusion, at which time it showed intense mitotic activity. The conditioned media were placed in cultures of fibroblasts, bovine adrenal capillary endothelial cells, and rat brain astrocytes. Cell proliferation in vitro was stimulated by the retinal extracts in all cell cultures. However, the cell proliferation in cultures with conditioned media from normal retina was similar to that in cultures with conditioned media from ischemic and proliferating retina. Although these data are consistent with the presence of soluble growth factors in the retina, they also indicate that release of these growth factors into the surrounding milieu after transient retinal ischemia is not altered to a degree that would explain the dramatic increase in mitosis.

Animals↗
PubMed1990

Characterization of glial involvement in proliferative diabetic retinopathy.

We studied the relationship of glial cells and other supporting tissues associated with newly formed blood vessels in proliferative diabetic retinopathy. Seventeen postmortem, freshly enucleated eyes from diabetic patients and 34 epiretinal and preretinal membranes removed during vitreous surgery for proliferative diabetic retinopathy were analyzed using the peroxidase-antiperoxidase method for light microscopy and protein A/gold labeling of ultrathin cryosections for transmission electron microscopy in addition to routine transmission and scanning electron microscopy. We found that glial cells are commonly and characteristically found in elevated diabetic proliferations and present at the vitreous surface. The newly formed blood vessels, however, were not seen at the edge of elevated epiretinal and preretinal membranes in early and intermediate stages. These results suggest that glial cells may extend beyond the vascularized areas of the proliferative tissue. It is possible that glial cells and their extracellular matrix contribute to the framework leading to the development of new blood vessels.

Cell Membrane↗
PubMed1990

Basic fibroblast growth factor stimulates 3H-thymidine uptake in retinal venular and capillary endothelial cells in vivo.

Recent studies have found basic fibroblast growth factor (bFGF), an angiogenic peptide, in retina and have suggested that bFGF is responsible for retinal vascular proliferation. To test the hypothesis that bFGF stimulates 3H-thymidine uptake in retinal vascular cells in vivo, we injected bFGF (100 ng) into the vitreous cavity of six cats at 0 hr and again at 24 hr. Eight control eyes received boiled bFGF or no injection. After 46 hr, 3H-thymidine was injected into the vitreous cavity of all eyes and 2 hr later the eyes were enucleated. Intense 3H-thymidine uptake was seen in eyes with bFGF (56 +/- 20 SD positive cells per section) but not in control eyes (7-10 positive cells per section (P less than 0.001). Trypsin digest preparations showed that the thymidine uptake was predominantly in the venular (89%) and capillary (10%) endothelium and not in arterioles (1%) (P less than 0.001). The data suggest that retinal venular endothelial cells respond preferentially to exogenous bFGF, and in part may explain their prominent role in the neovascular process. In a second group of experiments to test the hypothesis that retinal ischemia releases a diffusable factor similar to bFGF that can cause 3H-thymidine uptake in retinal vascular cells, we created branch retinal vein occlusion in six cat eyes. The fellow eyes received no injections. In the eyes with branch vein occlusion there was an intense 3H-thymidine uptake within the distribution of the occluded vein (84 +/- 77 SD positive cells per section), but none in the areas outside the occluded vein (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Cervical catecholamine-secreting paraganglioma in the pterygopalatine fossa.

A 25-year-old man was admitted for examination to determine the cause of hypertension. High levels of noradrenaline in plasma and urine were seen, suggesting that the patient had an adrenal or extra-adrenal pheochromocytoma. However, whole-body scintigraphy using the isotope of [131I] meta-iodo-benzylguanidine (131I-MIBG) failed to find the presence of a catecholamine-secreting tumor. The highest level of noradrenaline was detected in plasma obtained from the left jugular vein after selective venous collections through femoral catheterization. Both the computed tomography and cerebral angiography showed a hen-egg-sized tumor located in the left pterygopalatine. After surgical removal of the tumor, high blood pressure and the levels of noradrenaline in plasma and urine were significantly decreased. Histopathological diagnosis was paraganglioma (catecholamine-secreting paraganglioma). The patient with cervical catecholamine-secreting paraganglioma is the first case where the tumor was isolated and located in the pterygopalatine fossa.

3-Iodobenzylguanidine↗
PubMed1985

Effects of nipradilol (K-351) on alpha-adrenoceptor mediated responses in various isolated tissues.

Nipradilol competitively antagonized norepinephrine- or phenylephrine-induced contractile responses of guinea-pig thoracic aorta. These actions of nipradilol were about 6 times less potent than those of phentolamine. Nitroglycerin showed a non-competitive antagonistic action on norepinephrine-induced contractions of aorta. Furthermore, nipradilol competitively inhibited norepinephrine-induced contractions of rat vas deferens and dose-dependently reduced the phenylephrine-induced inhibitory responses in rabbit ileum. These antagonistic actions of nipradilol were 30 to 100 times less potent than those of phentolamine. Nitroglycerin did not appreciably affect these alpha-adrenoceptor mediated responses in rat vas deferens and rabbit ileum. The inhibitory action of clonidine on the twitch contraction of rat vas deferens produced by intramural stimulation was only slightly antagonized by nipradilol (pA2 = 5.4). Nipradilol and nitroglycerin showed a non-competitive antagonistic action on clonidine-induced contractions of canine saphenous vein after the exposure to phenoxybenzamine, while phentolamine competitively inhibited the clonidine responses. These results suggest that nipradilol possesses an alpha 1-adrenoceptor blocking action; it possesses very weak or practically no presynaptic alpha 2-blocking activity but shows a non-competitive antagonistic action on postsynaptic alpha 2-adrenoceptor mediated contractile responses.

Adrenergic alpha-Antagonists↗