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Biomedical subjects

R Manabe

Publications and source records attributed to R Manabe.

At least 73 records · Page 4Linked to original sources
PubMed1987

Dome formation in cell cultures of chick embryo retinal pigment epithelium and effects of ouabain and 2,4-dinitrophenol thereon.

Cells from chick embryo retinal pigment epithelium were cultured on glass slips. The primary culture cells formed confluent cell layers which were studded with a number of domes. The domes had usually appeared by the fourth day of culture and were susceptible to 3 X 10(-6) M ouabain and 10(-4) M 2,4-dinitrophenol, indicating that fluid was transepithelially transported from the apical to the basal side by means of an energy-requiring and ouabain-sensitive mechanism. Other than domes, small blisters appeared after 4-10 days of culture. They were also susceptible to the metabolic inhibitors.

2,4-Dinitrophenol↗
PubMed1987

Indomethacin and the epinephrine-induced breakdown of the blood-ocular barrier in rabbits.

Using aqueous and vitreous fluorophotometry, the authors examined the blood-aqueous and blood-retinal barrier functions in three groups of pigmented rabbits. Epinephrine (1.25%) was applied topically five times daily and indomethacin (0.5% sesame oil suspension) was applied topically three times daily to one eye of each of the animals in Group 1; under the same regimen, epinephrine and indomethacin placebo were administered to one eye of each of the animals in Group 2 and epinephrine placebo and indomethacin placebo were administered to one eye of each of the animals in Group 3. Fluorophotometry was done 1, 2, and 3 months after drug administration. The results showed that epinephrine induced disruption of the blood-aqueous barrier 2 and 3 months after drug administration, and that the magnitude of this disruption increased with time. Epinephrine also induced disruption of the blood-retinal barrier 3 months after drug administration. Indomethacin significantly prevented disruption of the blood-aqueous barrier at 2 and 3 months and significantly prevented disruption of the blood-retinal barrier at 3 months. The magnitudes of the barrier disruptions in eyes treated with both epinephrine and indomethacin were slightly higher than, or the same as, those of the control eyes. The results strongly indicated that the epinephrine-induced disruption of the blood-ocular barrier was partially caused by prostaglandins and other cyclo-oxygenase products whose biosynthesis was initiated by epinephrine.

Animals↗
PubMed1986

Effects of intravenous administration of a calcium antagonist on prostaglandins and thromboxane in plasma and urine in humans.

The effects of a calcium antagonist [Nicardipine hydrochloride (NH)] on the prostaglandin [prostaglandin E2 (PGE2), and 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha)] and thromboxane B2 levels in the blood and urine were examined in 6 patients with essential hypertension following intravenous infusion of NH for 120 minutes. At the same time, the plasma renin activity (PRA), plasma aldosterone concentration (PAC), and plasma and urinary electrolyte levels were also determined. During NH administration, the blood pressure was significantly decreased (p less than 0.05) with an increased pulse rate (p less than 0.05). PRA was significantly increased after NH loading (p less than 0.05) but PAC showed no change. The plasma PGE2 and 6-keto-PGF1 alpha levels tended to increase slightly, while the blood thromboxane B2 level showed a decreasing tendency. The 6-keto-PGF1 alpha to thromboxane B2 ratio was significantly increased after NH loading as compared to the preloading ratio (p less than 0.05), and then returned to the preloading value at about 30 minutes after discontinuation of NH loading. The urinary excretions of PGE2, 6-keto-PGF1 alpha and thromboxane B2, PGE2 and 6-keto-PGF1 alpha tended to decrease after NH loading. In particular, the decrease in PGE2 was statistically significant (p less than 0.05). No change occurred in the urinary excretion of thromboxane B2. The above findings indicate that NH increased the plasma 6-keto-PGF1 alpha to thromboxane B2 ratio but decreased the urinary excretion of prostaglandins. In addition, the possible involvement of an enhanced 6-keto-PGF1 alpha/thromboxane B2 ratio in part of the hypotensive mechanism of NH is suggested.

6-Ketoprostaglandin F1 alpha↗
PubMed1986

Photokeratoscopy in fitting contact lens after penetrating keratoplasty.

The formula based on keratometric readings which is generally used is unsatisfactory for fitting contact lenses after penetrating keratoplasty, possibly owing to lack of information on the peripheral corneal toricity. In these studies a photokeratoscope was used to examine the entire graft topography. In all cases the corneal configuration became more normal after suture removal, but a considerable toricity still remained, especially near the graft-host junction. One month after removal of sutures spherical hard contact lenses (polymethylmethacrylate, PMMA) were fitted to 30 patients in accordance with data obtained by computerised analysis of the photokeratograms. Of the 30 patients (contact lens wearers) 27 (90%) obtained a stable vision of better than 20/30 for eight hours daily, and 24 (80%) achieved a stable vision of 20/20 for their full waking hours. After one year the contact lens wearers showed a significant decrease in the extent of astigmatism when compared with the non-contact-lens wearers (10 patients). These results suggest that the photokeratoscope can be more useful than ordinary keratometers in fitting contact lenses after keratoplasty, and that hard contact lenses have moulding effects on the graft topography.

Adolescent↗
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

Cytochrome P-450 and related components of the microsomal electron transport system in the bovine ciliary body.

Microsomes were prepared from bovine ciliary bodies. The contents of cytochrome P-450 and related components of the microsomal electron transport system were determined. The cytochrome P-450 content was 32 pmoles/mg protein, which was about 4% that in rat liver. The cytochrome b5 content was 59 pmoles/mg protein. The NADH-cytochrome c reductase and NADPH-cytochrome c reductase activities were 268 and 18 nmoles/min/mg protein, respectively. The ethoxyresorufin deethylase activity was 2.1 pmoles product formed/min/mg protein.

Animals↗
PubMed1986

A newly established cell line of rabbit lens epithelium.

Rabbit lens epithelial cells have been cultured continuously for more than 24 months (200 generations) in monolayers. Their morphology resembled cobblestones when confluent and was spindle-shaped during growth. The doubling time was 40 hours. The cells were capable of colony formation and their plating efficiency was about 6%. They had immunoreactivity to antiserum to the crystalline-rich supernatant of rabbit lens homogenate. Therefore, it was concluded that they were a permanent cell line and they were named TOTL-86 cells.

Animals↗
PubMed1986

Corneal endothelial cell damage associated with intraocular gas tamponade during pars plana vitrectomy.

A prospective study was conducted of corneal endothelial damage associated with intraocular gas tamponade during pars plana vitrectomy performed in 44 patients. In addition to vitrectomy or combined vitrectomy-lensectomy, 25 patients (the gas-treated group) underwent intraocular gas tamponade, which was not performed in 19 patients (the control group). The central corneal endothelium was examined with a specular microscope preoperatively and 3 months postoperatively. Endothelial changes were quantitated by computerized morphometric analysis of individual cells. A total of 20 eyes were phakic after vitrectomy, 13 eyes in the gas-treated group and 7 eyes in the control group. The mean endothelial cell loss for the gas-treated group (1.9%) did not differ significantly from that for the control group (1.8%). Twenty-four eyes were aphakic after vitrectomy, 12 eyes in the gas-treated group and 12 eyes in the control group. The gas-treated group had a significantly greater cell loss (28.3%) than those in the control group (16.3%).

Air↗
PubMed1985

A new punctum plug.

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Equipment and Supplies↗
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

Co-existence of glucagon- and substance P-like immunoreactivity in the chicken retina.

This immunohistochemical study of chicken retina using flat-mounts shows that pancreatic glucagon- and substance P-like immunoreactive amacrine cells have more heterogeneous subpopulations than was previously understood to be the case. Using double-staining immunohistochemical procedures we demonstrate that a substantial proportion of all subtypes of glucagon-like immunoreactive cells contain substance P-like immunoreactivity and that the ratio of the amacrine cells containing both peptides to total immunoreactive cells varies according to position in the retinal and cell type. These results suggest that retinal cells may have different functions according to position or cell type.

Animals↗
PubMed1985

Actin organization in migrating corneal epithelium of rabbits in situ.

We have found previously that fibronectin enhances the migration of rabbit corneal epithelium both in vitro and in vivo. In this paper we report a change of actin localization in migrating corneal epithelium as determined by immunofluorescent microscopy. Rabbit cornea was cut into small blocks and cultured in TC-199 medium. In the normal cornea, actin was detected as diffuse fluorescence at each epithelial layer. After 8 hr of cultivation epithelial cells had not started to migrate significantly, but actin had accumulated at the cell membrane. After 24 hr, epithelial migration had begun, and actin-specific fluorescence was detected mainly in the basal cell layer at the leading edge. When fibronectin or epidermal growth factor was added to the culture medium, epithelial migration began 8 hr after initiation of culture, and at 24 hr actin-specific fluorescence at the basal side of the migrating epithelial cells appeared stronger than that of a control group cultured in TC-199 unsupplemented medium. At the same time, fibronectin-specific fluorescence was more intense beneath the migrating epithelial cells. It is known that fibronectin has an affinity to collagen, and thus it might coat the cut surface of the stroma. Epithelial cells may attach then to the stroma via coated fibronectin. When a large quantity of exogenous fibronectin is added or when fibronectin is synthesized by the addition of epidermal growth factor, it may further stimulate the organization of intracellular actin from globular form (G-actin) to fibrilar form (F-actin). As a result, the change of intracellular localization and appearance of organized actin molecule might lead to cellular migration.

Actins↗
PubMed1985

Clinical evaluation of fibronectin eyedrops on epithelial disorders after herpetic keratitis.

The clinical efficacy was investigated of fibronectin eyedrops on the nonhealing corneal epithelial defect after herpetic keratitis. Fibronectin eyedrops were prepared from the patient's own blood plasma by an affinity chromatography using gelatin-coupled agarose gel and by gel filtration technique. Twenty eyes with metaherpetic trophic ulcer with persistent epithelial defect that had not responded to conventional therapy were treated by the instillation of fibronectin eyedrops 6 times a day. The mean +/- standard deviation duration of epithelial defect was 61.5 +/- 66.1 days. The epithelial defects healed within 15.6 +/- 12.4 days. These results suggest that fibronectin eyedrops are a possible effective therapeutic approach in nonhealing corneal epithelial defect after herpetic keratitis.

Adolescent↗