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Biomedical subjects

S Tsuboi

Publications and source records attributed to S Tsuboi.

At least 145 records · Page 8Linked to original sources
PubMed1986

Aspects of electrolyte transport across isolated dog retinal pigment epithelium.

Transport of Na and Cl across the isolated dog retinal pigment epithelium (RPE) choroid was investigated. Under the short-circuit condition, a net Na flux was observed from choroid to retina and a net Cl flux was determined in the opposite direction. The current created by the net flux of these two ions was larger than the short-circuit current (SCC). Addition of 10(-5) M ouabain to the apical side inhibited net fluxes of both Na and Cl, whereas it reduced the SCC 84%. Addition of 10(-4) M furosemide to the apical side inhibited net Cl flux but had no effect on the net Na transport. The 10(-4) M furosemide reduced the SCC 38%. These drugs had no effect when applied to the basal side. Thus the transport of both Na and Cl depends on the Na-K-ATPase in the apical membrane of the dog RPE. A furosemide-sensitive neutral carrier at the apical membrane is suggested for the transport of Cl. Replacement of HCO3 with SO4 in the bathing solution caused an increase in the SCC, indicating the choroid-to-retina movement of HCO3 across the short-circuited dog RPE choroid.

Animals↗
PubMed1986

Effect of ipriflavone on bone changes induced by calcium restricted, vitamin D deficient diet in rats.

The preventive effect of ipriflavone, 7-isopropoxy-isoflavone, on the development of experimental osteopenia in rats was studied. Male Wistar rats (4 weeks old) on a calcium restricted, vitamin D deficient diet were given a daily oral administration of ipriflavone. The administration of ipriflavone (100 mg/kg BW/day) for 40 days significantly inhibited a decrease in the cortical thickness (14.0 +/- 1.6 vs. 17.1 +/- 2.9%, mean +/- SD, p less than 0.05) and bone calcium content (62 +/- 4 vs. 67 +/- 2 mg, p less than 0.05) in the femora of rats induced by a mild calcium restricted (0.3%), vitamin D deficient diet. This compound did not affect serum calcium levels in this condition. But a dose of 20 mg/kg BW/day of ipriflavone was insufficient to inhibit a decrease in bone calcium content. In rats fed on a more severe calcium restricted (0.03%), vitamin D deficient diet, the administration of ipriflavone (100 mg/kg BW/day) did not significantly affect the cortical thickness or calcium content. Intestinal calcium absorption measured by the in situ loop method was not significantly different between rats fed with a severe calcium restricted (0.03%), D deficient diet with or without ipriflavone (20 or 100 mg/kg BW/day) These results demonstrate that the new compound, ipriflavone, partially prevents bone calcium loss induced by a mild calcium restricted (0.3%), vitamin D deficient diet in rats. However, the precise mechanism of action of this compound remains unknown.

Animals↗
PubMed1986

[A case of chronic subdural hematoma in a hemodialyzed patient].

In proportion to a rapid increase of dialysis patient, death caused by neurological complications is increasing annually among long-term hemodialyzed patients. A case of chronic subdural hematoma during long-term hemodialysis is presented. A 35-year-old male had undergone hemodialysis three times weekly for four years. He had marked changes in body-weight and blood pressure between hemodialysis. In March 1983, he had a headache, vomiting, and left hemiparesis. The CT scan showed a right subdural hematoma. He was admitted to our hospital 10 days later because of progressive hemiparesis and speech disturbance. The neurological examination showed left hemiparesis with sensory deficit and dysarthria. The CT scan showed an increase in the size of the subdural hematoma. Bleeding time was over 10 minutes. A right-sided burr hole was made and altered blood was removed and irrigated. After operation, headache and weakness rapidly subsided, but the next morning, attacks of convulsion occurred. The CT scan showed the rebleeding in the subdural space. After correcting the level of serum potassium by hemodialysis, a right parietal craniotomy was performed. Hematoma of about 100 g was removed and the capsule of the hematoma showed organized tissue histologically. Postoperatively, although attacks of convulsion occurred temporarily, he gradually improved. The levels of serum potassium and BUN were controlled by several treatments of hemodialysis. He was discharged with only mild hemiparesis. Subdural hematoma caused by hemodialysis is a very important complication. Chronic subdural hematoma is sometimes very difficult to differentiate from dysequilibrium syndrome or dialysis dementia. The CT scan is a very valuable examination to rule out subdural hematoma.

Adult↗
PubMed1986

Permeability of the isolated dog retinal pigment epithelium to carboxyfluorescein.

Outward (retina to choroid) and inward (choroid to retina) permeabilities of carboxyfluorescein and fluorescein in the isolated dog retinal pigment epithelium (RPE)-choroid were determined. Outward permeability was 9 and 47 times larger than inward permeability for carboxyfluorescein and fluorescein, respectively. The outward permeability of carboxyfluorescein was seven times lower than that of fluorescein, whereas there was no statistical difference between the inward permeabilities. Carboxyfluorescein is thus distinguished from fluorescein by its low affinity to the outwardly directed organic anion transport system. 10(-4) M probenecid caused greater than 98% inhibition of the outward transport of 6 X 10(-5) M carboxyfluorescein and 6 X 10(-6) M fluorescein.

Animals↗
PubMed1985

Fluid dynamics in eyes with rhegmatogenous retinal detachments.

Inward and outward permeabilities to sodium fluorescein at the blood-retinal barrier were measured by kinetic vitreous fluorophotometry in ten eyes with rhegmatogenous retinal detachments. Fellow eyes were used as controls. Inward permeability of eyes with detachments was significantly larger than that of controls (P less than .005), suggesting damage to the blood-retinal barrier in eyes with detachments. Outward permeability of eyes with detachment and retinal holes was slightly less than that of controls, but the difference was not statistically significant. However, outward permeability of eyes with detachments and with retinal tears was significantly larger than that of controls (P less than .05). This increased outward permeability may be attributed to the increased fluid flow posteriorly through the break across the retinal pigment epithelium.

Adolescent↗
PubMed1985

Experimental retinal detachment. X. Effect of acetazolamide on vitreous fluorescein disappearance.

Retinal detachments were created in one eye of each of eight cynomolgus monkeys. Total vitrectomy was performed in the fellow eyes. Fluorophotometry was used to study the rate of disappearance of fluorescein injected into the vitreous cavity. The rate of fluorescein loss via the anterior chamber accounted for only 1% to 3% of the total rate of vitreous fluorescein loss in eyes with retinal detachment or in fellow eyes. Posterior loss of fluorescein (presumably across the retinal pigment epithelium) increased by 25% following intravenous acetazolamide in eyes with retinal detachment and 22% in fellow eyes. It is concluded that acetazolamide increases the rate of fluid absorption across the retinal pigment epithelium.

Acetazolamide↗
PubMed1984

Ophthalmic and norophthalmic acid in lens, liver, and brain of higher animals.

A sensitive high-performance liquid chromatographic method for the determination of nanomole levels of ophthalmic and norophthalmic acid has been described. The procedure is based upon the conversion of amino group to 2,4-dinitrophenyl derivatives and the detection at 420 nm. This method was applied to the determination of the peptides in lens, liver, and brain of several animals. Mean recoveries were 93.6% for ophthalmic acid and 92.3% for norophthalmic acid added to cattle lens homogenate.

Animals↗
PubMed1984

Subretinal neovascularisation in eyes with localised inferior posterior staphylomas.

We report seven cases of subretinal neovascularisation with inferior posterior staphyloma. The upper border of the shallow staphyloma, detected by B-mode echography, invaded the macular area, and there was a neovascular net at the edge of the staphyloma. Three of the cases showed chorioretinal atrophy at the upper edge of the staphyloma in the same location as the neovascular net. Our cases were identical to those of subretinal neovascularisation in high myopic eyes in which the rupture of Bruch's membrane was related to the deformity of the scleral shell. As our cases included not-high-myopic eyes, the results suggest that the identical mechanism might be involved in the occurrence of neovascular maculopathy in the pathological high myopic eye and in the not-high-myopic eye with posterior staphyloma. Localised inferior posterior staphyloma may be an important cause of 'idiopathic' subretinal neovascularisation.

Adult↗
PubMed1984

S-(1,2-dicarboxyethyl)glutathione and S-(1,2-dicarboxyethyl)L-cysteine in lens.

S-(1,2-Dicarboxyethyl)glutathione and S-(1,2-dicarboxyethyl)L-cysteine were determined by high performance liquid chromatography after reaction with 2,4-dinitrofluorobenzene. By this method the former could be determined in the range 4.05 mumol/l-815 mumol/l, and the latter in the range 1.45 mumol/l-1.45 mmol/l. The recovery from cattle lens homogenate was 90.0 +/- 3.2% for S-(1,2-dicarboxyethyl)glutathione and 95.3 +/- 3.1% for S-(1,2-dicarboxyethyl)L-cysteine. Using this method S-(1,2-dicarboxyethyl)-glutathione and S-(1,2-dicarboxyethyl)L-cysteine were determined in lenses of several vertebrates and in rat lens during cataract formation by galactose.

Animals↗
PubMed1984

Electrical characteristics of the isolated dog ciliary body.

Transepithelial potential difference and short-circuit current of the dog ciliary body were measured in vitro in an Ussing-type chamber using HEPES-buffered solution containing bicarbonate. Their values were -1.35 +/- 0.08 mV (mean +/- S.E.M., n = 52) and -23.6 +/- 1.7 microA/cm2, respectively. At 10(-4) M, ouabain reduced the short-circuit current upon to either side of the chamber. On the other hand, at 10(-5) M of furosemide to the aqueous side, the short-circuit current was reduced. However even at 10(-3) M, this drug had no effect when applied to the stromal side. Behavior of the dog ciliary body towards these two inhibitors was compared with that of the toad and rabbit tissues.

Animals↗
PubMed1984

Detection of aflatoxin B1 in serum samples of male Japanese subjects by radioimmunoassay and high-performance liquid chromatography.

Aflatoxin B1 (AFB1) was detected in serum samples of healthy Japanese males by radioimmunoassay and high-performance liquid chromatography. Blood samples were obtained from 20 subjects after fasting and from 80 subjects after lunch. The subjects ranged in age from 20 to 63 years of age. Measurement of AFB1 in the samples was performed by radioimmunoassay and was confirmed by high-performance liquid chromatography using a mu Porasil column and a C18-mu Bondapak column after the conversion of AFB1 to its water adduct AFB2a. AFB1 was detected in 5 of 20 fasting blood samples [20 to 56 pg/ml of serum; 33.6 +/- 14.6 (S.D.)] and in 29 of 80 serum samples taken after lunch (20 to 1169 pg/ml of serum; 218.1 +/- 268.3). Mass spectral analysis of the material obtained after high-performance liquid chromatography separation from serum samples confirmed the presence of AFB1.

Adult↗
PubMed1984

Measurement of retinal permeability to sodium fluorescein in vitro.

Fluorescein permeabilities of isolated dog retinal pigment epithelium (RPE)-choroid and sensory retina were measured individually. Retina to choroid (outward) permeability of sodium fluorescein was significantly larger than choroid to retina (inward) permeability at RPE-choroid under both open- and short-circuit conditions. Outward permeability was decreased by the addition of 10(-3) M KCN and of 10(-4) M probeneside but was not affected by 10(-6) M ouabain. These drugs decreased transepithelial potential and short-circuit current. No directional difference of fluorescein permeability for sensory retina was found. Active transport of fluorescein across RPE from retina to choroid is suggested. Fluorescein permeability of sensory retina was larger than inward but less than outward permeability of RPE-choroid. The result indicates that the sensory retina acts as a diffusion barrier for sodium fluorescein.

Animals↗