Ciliary ganglion stimulation. I. Effects on aqueous humor inflow and outflow. (57/1321)

Stimulation of the ciliary ganglion in an enucleated, arterially perfused cat eye preparation produced a sustained increase in aqueous humor formation and an increase in the rate of aqueous humor outflow. The increased aqueous humor formation induced by ciliary ganglion stimulation has been found to be pressure-dependent and therefore suggests that ultrafiltration may be the underlying mechanism of action. No change in capillary permeability of the ciliary body could be demonstrated.  (+info)

UV absorption by uric acid in diurnal bird aqueous humor. (58/1321)

PURPOSE: To analyze the components responsible for the UV absorbance in diurnal bird aqueous humor. METHODS: The absorbance studies were carried out using a Hitachi spectrophotometer (U 2000). Uric acid was determined by high-performance liquid chromatography (LC-10 system; Shimadzu, Kyoto, Japan). Chicken and turkey eyes were examined. RESULTS: The UV absorbance in chicken aqueous was largely accounted for by the presence of protein, tryptophan, tyrosine, ascorbic acid, and uric acid. Ascorbic acid was low (23 micromol/l). Uric acid was, on the other hand, remarkably high (151 micromol/l) compared with that in mammals (cattle, 16 micromol/l). Principally the same results were obtained in chicken and turkey. CONCLUSIONS: Uric acid is a significant UV-absorbing substance in the aqueous humor of diurnal birds with its peak absorbance at 292 nm. The hypothesis that the aqueous humor acts as a UV filter seems to be valid also for the avian eye. However, in these eyes uric acid fulfills the role that ascorbic acid does in mammals.  (+info)

Effect of local corticosteroids on antibody-forming cells in the eye and draining lymph nodes. (59/1321)

Significant numbers of antibody-forming cells (AFC) have been found in the cornea, uveal tract, and draining lymph nodes after the intracorneal injection of bovine gamma-globulin (BGG). To study the effect of locally administered corticosteroids on these antibody-forming tissues, we made unilateral intracorneal injections of rabbit eyes with BGG. These we followed immediately with subconjunctival injections of 10 mg. of triamcinolone suspension, and then with a second round of 10 mg. injections seven days later. A control group of animals received the BGG injections followed by two subconjunctival saline injections. We killed the animals on postinjection days 6, 9, 12, 15, and 21, and tested the draining lymph nodes, homolateral uveal tissue, and homolateral cornea for AFC by a modification of the Jerne placque technique. The local steroids had no effect on the number of AFC produced in the draining lymph nodes or on the circulating antibody response, but they reduced the number of AFC in the homolateral uveal tracts and corneas. Clinically there was less inflammatory response in the steroid-treated eyes than in the control eyes. The possible mechanisms by which corticosteroids achieve their anti-immunologic and anti-inflammatory benefits are discussed.  (+info)

The inhibiting effect of indomethacin on the disruption of the blood-aqueous barrier in the rabbit eye. (60/1321)

The aqueous flare (AF) of an intact rabbit eye was measured by a photoelectric instrument. Local application of prostaglandin E2 (PGE2) and its precursor arachidonic acid (AA) gave an almost identical increase of the AF. The response to AA but not to PGE2 was inhibited by pretreating the eye locally with a solution of indomethacin. The ability of indomethacin to inhibit the aqueous flare response (AFR) to an agent is assumed to indicate that a kind of prostaglandin is the effector of the AF. Indomethacin blocked the AFR to infrared irradiation of the iris and to intravenous administration of endotoxin but not to subcutaneous administration of alpha-melanocyte-stimulating hormone (alpha-MSH).  (+info)

Effect of IOP elevation on matrix metalloproteinase-2 in rabbit anterior chamber. (61/1321)

To investigate changes in the level of matrix metalloproteinase-2 (MMP-2) in the anterior chamber of rabbit with intraocular pressure (IOP) elevation. The IOP was elevated with scleral encircling in 12 rabbits. In the control group (4 rabbits), IOP was not changed after scleral encircling, and in group 1 (4 rabbits) and 2 (4 rabbits), IOP was elevated about 10 and 20 mmHg respectively after scleral encircling. At 2 days after scleral encircling, aqueous sampling was performed and levels of MMP-2 were checked by Western blots and gelatin zymograms. The greater the IOP elevation, the more MMP-2 expression in the anterior chamber by Western blots and gelatin zymograms. The increase in MMP-2 expression in response to IOP elevation may have important implications for the IOP feedback control mechanism.  (+info)

The role of NaKCl cotransport in blood-to-aqueous chloride fluxes across rabbit ciliary epithelium. (62/1321)

PURPOSE: To evaluate the role of NaKCl cotransport in short-circuit current (Isc) and chloride fluxes across rabbit ciliary epithelium mounted in a Ussing-type chamber. METHODS: Bilayered intact ciliary epithelium free of stroma was obtained after perfusion and dissection of rabbit eyes and mounted in an Ussing-type chamber. The effects of bumetanide and other drugs on Isc and transepithelial 36Cl fluxes in bicarbonate-containing Ringer's were determined. Immunoblot analysis was performed by standard techniques. RESULTS: Bumetanide (100 microM) applied to the blood (pigmented epithelium [PE]) side of the ciliary bilayer caused a dose-dependent decrease in Isc from 18.2 +/- 2.2 to 10.4 +/- 1.4 microA/cm2 (43%). Bumetanide applied to the aqueous (nonpigmented epithelium [NPE]) side of the tissue inhibited Isc by only 12%. Immunoblots of dissected NPE and PE tissue probed with an antibody to mammalian NaKCl cotransporter detected approximately 10 times more NaKCl cotransporter protein in PE than in NPE. 36Cl flux studies revealed a PE-to-NPE chloride flux of 180.3 +/- 37.2 microEq/cm2 per hour and an NPE-to-PE flux of 72.3 +/- 22.9 microEq/cm2 per hour, indicating a net PE-to-NPE flux of 108.0 +/- 31.3 microEq/cm2 per hour across rabbit ciliary epithelium. Bumetanide inhibited the PE-to-NPE chloride flux by 52% but did not inhibit the NPE-to-PE flux. Isoproterenol (10 microM) added to the PE side of the bilayer increased Isc by a dose-dependent 53%. Prior addition of bumetanide to the PE side blocked the increase due to isoproterenol by 37%. Isoproterenol (10 microM) stimulated the PE-to-NPE chloride flux by 75% but had no stimulatory effect on the NPE-to-PE chloride flux. 4,4'Diisothiocyanatostilbene-2,2'disulfonic acid (DIDS) inhibited Isc when added to either side of the bilayer but was more potent at low concentrations (<100 microM) when added to the NPE side and more potent at higher concentrations (>100 microM) when added to the PE side. Prior addition of 1 mM DIDS to the NPE side decreased isoproterenol stimulation of Isc by 56%. CONCLUSIONS: NaKCl cotransporters located primarily on the blood side of rabbit ciliary epithelium contribute to aqueous-negative Isc and to blood-to-aqueous chloride transport across the tissue in bicarbonate-containing medium. DIDS-inhibitable mechanisms, possibly including HCO3-Cl exchange and Cl channels, also play a role. Isoproterenol stimulation of Isc involves coordinate upregulation of PE-side NaKCl cotransport and an NPE-side DIDS-inhibitable mechanism(s).  (+info)

IL-6 antagonizes TGF-beta and abolishes immune privilege in eyes with endotoxin-induced uveitis. (63/1321)

PURPOSE: To determine the immunosuppressive status of aqueous humor (AqH) from mouse eyes afflicted with endotoxin-induced uveitis (EIU) and to identify the relevant cytokines responsible for immunomodulatory activity within EIU AqH. METHODS: Bacterial lipopolysaccharide (LPS) was injected into hind footpads of C3H/HeN mice; and AqH, collected at 6, 12, 24, and 48 hours, was evaluated for content of transforming growth factor (TGF)-beta, tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, IL-6, and interferon (IFN)-gamma and capacity to suppress anti-CD3-driven T-cell proliferation. Cytokine mRNA expression in iris-ciliary body (I/CB) was analyzed by RNase protection assays. RESULTS: During 6 to 24 hours after LPS injection, total TGF-beta levels in AqH increased even though the fluid lost its capacity to suppress T-cell activation. At this time, AqH contained high levels of IL-6, and I/CB contained high levels of IL-6 mRNA. When IL-6 was neutralized with specific antibodies, inflamed AqH reacquired its capacity to suppress T-cell activation, which correlated with high levels of TGF-beta. Coinjection of IL-6 plus antigen into the anterior chamber of the eye of normal mice prevented antigen-specific anterior chamber-associated immune deviation (ACAID). CONCLUSIONS: LPS-induced intraocular inflammation is associated with local production of IL-6, which robs AqH of its immunosuppressive activity, perhaps by antagonizing TGF-beta. The fact that IL-6 antagonized ACAID induction in normal eyes suggests that strategies to suppress the intraocular synthesis of IL-6 may reduce inflammation and restore ocular immune privilege.  (+info)

Subretinal fluid levels of topical, oral, and combined administered ciprofloxacin in humans. (64/1321)

AIMS: To investigate the subretinal fluid (SRF) penetration of ciprofloxacin following topical, oral, and combined administration. METHODS: 34 patients undergoing conventional retinal reattachment surgery were randomly assigned to three groups. Twelve patients received topical ciprofloxacin, 11 patients received oral ciprofloxacin, and the other 11 patients received combined drug administration. SRF drug level was measured by using high performance liquid chromatography method. RESULTS: The highest drug concentrations of all tested modes were attained following combined administration and lowest following topical administration (p<0.001). The SRF drug concentration following oral administration was also significantly higher than that of topical administration (p<0.001). Concentrations after oral and combined administration did not differ significantly (p = 0.217). CONCLUSIONS: Topical ciprofloxacin can penetrate SRF. Ocular bioavailability of ciprofloxacin in SRF after oral and combined administration is equivalent.  (+info)