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PubMed1982

Experimental retinal detachment. IV. Aqueous humor dynamics in rhegmatogenous detachments.

Unilateral rhegmatogenous retinal detachments were produced in 14 cynomolgus monkeys. A total vitrectomy was performed in the fellow eyes. Two groups of monkeys were studied two to four months and ten to 19 months after creation of the detachment. Aqueous flow was determined fluorimetrically from decay of fluorescein isothiocyanate dextran 70 following anterior chamber injection. Outflow facility was measured by constant pressure perfusion. The intraocular pressure was 7.6 and 5.0 mm Hg lower in the detached eyes of the short- and long-term groups, respectively. Aqueous flow was reduced by 70% in the detached eyes of both groups. Outflow facility was slightly lower in the detached eyes (0.21 v 0.27 microL/min/mm Hg). Apparently, reduced aqueous humor formation accounts for hypotony in the detached eyes. However, shunting of posterior chamber aqueous into the subretinal space and across the blood-retinal barrier by a mechanism independent if IOP is possible.

Animals↗
PubMed1977

Physiology and chemistry of cerebrospinal fluid, aqueous humor and endolymph in Squalus acanthias.

By means of the appropriate isotopes injected into the spiny dogfish, Squalus acanthias, the transfer of all major ions into cerebrospinal fluid (CSF), aqueous humor (A) and endolymph (E) was studied. In addition, the effect of raising pCO2 in sea-water upon HCO3- concentration of these fluids was measured. In the several types of experiments, acetazolamide or methazolamide was used to inhibit completely carbonic anhydrase. The rates of fluid formation and ion transfer in CSF and A were fairly close, but those for E were far slower. The general pattern of ion transport in the three fluids were the same, Na+ (or Na+ + K+ in E) entry greater than Cl - entry, and the difference was HCO3-. The greater rate constants for HCO3-, increase in its entry rate by elevation of pCO2, and inhibition of its appearance by the sulfonamides, show that this is a special case of transport; the ion is formed in secretory cells from gaseous CO2 + OH-. Secretory cells at sites of formation of all the fluids contain both carbonic anhydrase and Na+-K+-ATP-ase, which subserve HCO3- formation and Na+ (or K+) transport. Comparison of these results with studies in mammals show that the vertebrate pattern for secretion of these three fluids is well established in the elasmobranch.

Adenosine Triphosphatases↗
PubMed1988

Antibodies to immunoglobulin-G in dog sera, synovial fluids and aqueous humor: a comparative study of rheumatoid factor assays, suitable for routine application.

The incidence of anti-IgG antibodies (rheumatoid factors, RF) in body fluids (sera, synovial fluids and aqueous humor) selected from 62 normal and 275 diseased dogs was studied. Fluids were assayed by canine versions of standard agglutinating and/or precipitating RF assays with routine application in human practice. The number of RF detected by dog IgG-coated particles was substantially higher by latex fixation test (LFT) than by modified Rose-Waaler (RW) test (61/144 vs. 14/144). This did not result from false positives by LFT since latex activity was completely inhibited by aggregated dog IgG. Some evidence is presented indicating that results obtained by standard RW in particular, but also those obtained by standard LFT, might be improved by modifying testing conditions currently used. Body fluids were further studied for the presence of precipitins to aggregated dog IgG in 0.6% agarose (gel precipitation test (GPT]. The frequency of RF was higher by GPT than by LFT, both in normal control fluids (for sera 26/52 vs. 19/52) and patient material (for sera 135/197 vs. 95/197). Thus, the canine RF appear to be a serum component with an unexpectedly high frequency in both normal and diseased dogs, but grossly underestimated by the recommended routine RF assays based on agglutination. The GPT, which combines a superior detection rate of theoretically also agglutinating RF with an inability to detect RF quantitatively, seems an ideal RF 'indicator' test to dictate improvements to the quantitative LFT/RW assays so as to facilitate RF detection at clinically relevant concentrations. Thus optimized, RW/LFT would provide the optimal detection apparatus for the ultimate isolation of the relevant 'RF' repertoire present, for comparative studies aimed ultimately at unraveling the etiopathogenesis of the 'real' RF.

Animals↗
PubMed1999

Effects of NG-nitro L-arginine and corticosteroids on aqueous humor levels of nitric oxide and cytokines after cataract surgery.

PURPOSE: To assess the efficacy of nitric oxide synthesis (NOS) inhibitor, topical steroids, and nonsteroidal anti-inflammatory drugs on aqueous levels of nitric oxide (NO) and cytokines after cataract surgery. SETTING: Research Laboratory, Inonu University Turgut Ozal Medical Center, Malatya, Turkey. METHODS: Fifteen rabbits had intercapsular phacoemulsification and were randomly divided into 3 treatment groups: Group 1 was treated with topical prednisolone acetate 1% drops 5 times a day for 1 week; Group 2, flurbiprofen 0.03% drops 5 times a day for 1 week; Group 3, a 0.1 cc subconjunctival injection of NG-nitro L-arginine (L-NAME) (150 mg/kg) 1 day and 3 days after surgery. Three rabbits serving as controls received a subconjunctival injection of an equal volume of balanced salt solution (BSS) at the same times as the L-NAME injections. Aqueous humor specimens were collected from each eye to determine NO and cytokine levels including interleukin-1-beta (IL-1 beta), interleukin-2R (IL-2R), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha). RESULTS: The levels of IL-1 beta and IL-6 were higher in Group 2 and the control group than in Groups 1 and 3 at all times. The differences were not statistically significant (P < .05). Nitric oxide and TNF-alpha levels in Groups 1 and 3 were significantly lower than in Groups 2 and the controls 1, 3, and 7 days postoperatively (P < .05). CONCLUSION: These findings suggest a strong inhibitory effect of NOS inhibitors and corticosteroids on aqueous levels of TNF-alpha and NO and no inhibitory effect on IL-1 beta and IL-6 levels after cataract surgery.

Animals↗
PubMed1989

Patterns of aqueous humor outflow in glaucomatous and nonglaucomatous human eyes. A tracer study using cationized ferritin.

We used cationized ferritin, which binds to negatively charged membrane surfaces, as a tracer to delineate the aqueous humor outflow pathway by perfusing it into the anterior chamber of 14 normal human eyes and five with primary open angle glaucoma. In the normal human eyes, diffuse labeling with cationized ferritin was evident throughout the outflow pathway, while in the glaucomatous eyes distinctly different staining patterns were noted. A decorating pattern similar to that seen in normal eyes was observed, as well as apparent areas of underperfusion, suggestive of possible segmental changes in aqueous outflow. These findings may support the hypothesis that primary open angle glaucoma is a segmental disease of the outflow system due to possible regional increases in resistance to aqueous outflow.

Adult↗
PubMed2002

Aqueous humor in primary open-angle glaucoma contains an increased level of CD44S.

PURPOSE: To determine whether the cell adhesion molecule CD44, the principal receptor of hyaluronan, is altered in the aqueous humor and the anterior segment of patients with primary open-angle glaucoma (POAG). METHODS: The trabecular meshwork (TM), iris, ciliary body, and sclera of POAG and age-matched control eyes preserved in ethanol were microdissected and subjected to 1% Triton X-100 solubilization at 4 degrees C. Western blot analysis was performed using monoclonal antibodies that recognize either CD44H (hematopoietic; extracellular domain) or CD44S (soluble ectodomain). The concentration of soluble CD44S in aqueous and microdissected tissues was measured by enzyme-linked immunosorbent assay (ELISA). RESULTS: ELISA of soluble CD44S of aqueous from eyes of patients with POAG indicated that the concentration of soluble CD44S is increased in comparison with that of aqueous from normal eyes (P < 0.0003). Western blot analysis and densitometry of POAG iris and ciliary body revealed a statistically significant increase in the Triton X-100 extraction of CD44H. The predominant increases were in the 180-kDa (P < 0.001) and the 85-kDa (P < 0.001) forms. ELISA of soluble CD44S indicated that the concentration is statistically decreased in iris (P < 0.05), ciliary body (P < 0.001), and TM (P < 0.005) of POAG eyes. CONCLUSIONS: Increased amounts of soluble CD44S in POAG aqueous and Triton X-100-solubilized CD44H characterized POAG in the iris and ciliary body. These soluble CD44 isoforms may influence the activity of the transmembrane CD44H by acting as inhibitors of CD44H and, thereby, adversely influence the cell survival of TM and retinal ganglion cells in POAG.

Aged↗
PubMed1984

The effect of vanadate on aqueous humor dynamics in cynomolgus monkeys.

Topical administration of 1% vanadate in a formulation designed to enhance penetration lowered intraocular pressure in monkeys' eyes. The decrease in intraocular pressure was associated with significant decreases in aqueous humor flow. Tonographic outflow facility was unaltered by topical vanadate.

Administration, Topical↗
PubMed1987

Cytological and immunological study of the aqueous humor in acute retinal necrosis syndrome.

We experienced 4 cases of acute retinal necrosis syndrome, and performed anterior chamber paracentesis as a diagnostic aid in their acute and convalescent phases. The aqueous humor obtained by it was used for measuring antibody titers to herpes group virus and electron microscopic observation. One case showed elevated titer to herpes simplex virus type 1 in the convalescent phase, while the other to varicella-zoster virus, suggesting that these 2 viruses could cause this disease. Electron microscopy showed persistent lymphocytes and macrophages throughout the course, while plasma cells appeared at the height of the inflammation corresponding to the locally elevated antibody titers. There was no electron microscopic evidence of viral infection in the aqueous cells examined.

Acute Disease↗
PubMed1984

Measurement of aqueous humor flow with scanning ocular fluorophotometers.

A one-dimensional scanning fluorophotometer (Fluorotron Master) and a two-dimensional scanning fluorophotometer (McLaren and Brubaker) were used to measure rate of aqueous humor flow in normal volunteers. The precision of three protocols of dye application and flow determination was investigated. In all three protocols rate of flow was determined by observing the rate of disappearance of topically-applied fluorescein during an 8-hour period. The three protocols studied were: 1) Two drops of 10% fluorescein washed away five minutes later immediately before beginning measurements of fluorescence. 2) Application of 0.25% fluorescein every 5 minutes for 30 minutes, 6 hours before beginning measurements. 3) Iontophoresis for 7 seconds and irrigation of eye immediately before beginning measurements. Rate of flow was calculated by the methods of Jones and Maurice. The results were compared to measurements made with a slit-lamp fluorophotometer using the technique described by Coakes and Brubaker. The most satisfactory method of measuring flow when either scanning fluorophotometer was employed was to instill fluorescein many hours before measurements begin (protocol 2).

Adult↗
PubMed2005

HPLC determination of pirenzepine dihydrochloride in rabbit aqueous humor.

Pirenzepine was considered as a pharmacologic agent of preventing form-deprivation myopia. To assess the ocular bioavailability of pirenzepine, a HPLC method for determination of pirenzepine in rabbit aqueous humor was developed. An HPLC system was used in the reverse phase mode for the determination of pirenzepine. A Luna RP18 5 microm 4.6 mm x 150 mm column was employed at 35 degrees C. The mobile phase was methanol/0.02 M KH2PO4/sodium 1-pentanesulfonate (350/650/1, v/v/m, pH was adjusted to 8.0 by dropping 1M NaOH). The flow rate was 1 ml/min. Pirenzepine was monitored at 280 nm. Sample treatment procedure consists of deproteinisation with methanol. Calibration curves fitted by plotting the peak area versus concentration were linear in the range 20-400 ng/ml. The limit of quantification (LOQ) of present method was 20 ng/ml. Within-day and inter-day coefficient of variation was lower than 10%. Analytical recoveries were determined as 92.4, 95.4 and 101.4% at concentrations of 40, 200 and 400 ng/ml. In conclusion, this HPLC method using a simple sample treatment procedure appears suitable for monitoring ocular concentration of pirenzepine.

Animals↗
PubMed1978

Continuous in vivo recordings of intraocular capillary and aqueous humor flows.

Multiple-point recordings of the initial slopes of xenon 133 and human serum albumin I125 washout from various ocular regions were utilized to visualize changes in capillary and aqueous humor bulk flow in vivo. Preservation of slope linearity is essential for sensitive responsiveness of recordings to flow change. Linearity is enhanced by the initial slope approach in which stability of physiological values and drug effects are maintained and slopes are closely fitted to multiple points. As examples of intraocular flow changes which may be observed and computed from such slopes, responses recorded in forty feline washout studies are presented and the fundamentals of washout recording interpretation are discussed.

Animals↗
PubMed1982

Unsaturated fatty acids alter aqueous humor dynamics and uveal flow.

We report the effects of four unsaturated fatty acids (UFAs) - arachidonic (AA), linoleic, alpha-linolenic and oleic acid - and one saturated fatty acid (stearic acid) on aqueous humor (AH) dynamics of the isolated arterially perfused cat eye. UFAs, but not stearic acid, increase inflow of AH and elevate IOP; they do not affect the size of the pupil except for AA which produces maximal constriction. Indomethacin blocks the AA induced increase in inflow and the constriction of the pupil but it does not prevent the rise in IOP; indomethacin does not block increased flow or IOP caused by linoleic acid. We conclude that the fatty acid moiety of UFAs affects the blood aqueous barrier and possibly also the outflow channels. AA has a dual effect since in addition to a general fatty acid effect, an AA induced cyclo-oxygenase product affects AH inflow and constricts the pupil. All UFAs dilate the iridial part and constrict the choroidal part of the ciliary processes; this may contribute to increased inflow of AH and elevation of IOP.

Animals↗
PubMed1988

Comparative pharmacokinetics of D- and L-alphamethyldopa in plasma, aqueous humor, and cerebrospinal fluid in rabbits.

The 2 stereoisomers of alphamethyldopa (alpha MD) were separately injected IV at 3 different doses (3, 10, 30 mg/kg) in anesthetized rabbits. Samples of plasma, aqueous humor (AH), and cerebrospinal fluid (CSF) were collected over a 300-min period. The concentration of the aminoacid (AA) was determined by liquid chromatography and electrochemical detection. Parameters obtained from kinetic analyses of the plasma concentrations were close to the values reported in other species. Linear elimination kinetics were observed in the dose range studied. A marked dose-dependent entry of alpha MD was observed in AH. A stereospecific active transport of alpha MD was evidenced in the AH since the concentration of the L-isomer reached values above the plasma levels. CSF entry of the AA was small when compared to AH kinetics. A limited passive diffusion of the AA in the brain could account for this phenomenon. However, greater availability of the L-stereoisomer was still observed in CSF. These alpha MD kinetic analyses illustrate the adaptation of AH and CSF removal procedures to the pharmacokinetic studies of the brain and ocular entry of AA isomers.

Animals↗
PubMed1998

Anti-angiogenic effect of TGFbeta in aqueous humor.

Neovascularization is mediated by various factors in ocular tissues. Recent studies have emphasized the role of vascular endothelial growth factor in the induction of angiogenesis. We have previously reported that aqueous humor (AH) suppressed vascular endothelial cell growth and angiogenesis. We speculated that the anti-angiogenic effect of AH is mediated by transforming growth factor beta (TGFbeta). In order to clarify the presence of TGFbeta in bovine AH, we applied it on the heparin-sepharose affinity column and prepared two fractions (bound and unbound fractions). We measured TGFbeta concentration in each fraction and examined how the anti-TGFbeta antibody decreased the inhibitory effect of AH on human umbilical vein endothelial cell growth and on in vitro angiogenesis. We found the presence of TGFbeta2, but not TGFbeta1, in the heparin bound fraction, and the inhibitory effect was detected in the heparin-bound fraction. Anti-TGFbeta antibody completely and dose-dependently extinguished the inhibitory effect of AH. We propose that the inhibitory effect of AH on endothelial cell growth and in vitro angiogenesis are both mediated by TGFbeta2. Our results indicate TGFbeta2 is normally present in AH and protects the eye tissue against abnormal neovascularization.

Animals↗
PubMed2005

Matrix metalloproteinases and their tissue inhibitors in aqueous humor of patients with primary open-angle glaucoma, exfoliation syndrome, and exfoliation glaucoma.

PURPOSE: To study extracellular matrix (ECM) metabolism by matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) in aqueous humor (AH) samples collected from primary open-angle glaucoma (POAG), exfoliation syndrome (EXS), and exfoliation glaucoma (EXG) in relation to samples derived from cataract control patients. MATERIALS AND METHODS: Seventy-one AH samples were collected during cataract extraction and trabeculectomy. The expression and molecular forms of MMP-2, -8, -9, -13, and -14 and tissue inhibitor of metalloproteinases-1 and -2 (TIMPs) were analyzed by Western immunoblotting. Gelatinase and collagenase activities were studied by zymography and type I collagen degradation assays, respectively. MMP-2 and TIMP-2 concentrations were measured by ELISA assays. RESULTS: By Western immunoblotting all the studied MMPs were mainly in their latent form in all diagnostic groups. Zymography demonstrated that MMP-2 represents the major gelatinase in AH. Similarly, type I collagenolytic activity was low and similar in cataract and glaucoma samples. In ELISA measurements the TIMP-2 levels were significantly elevated in glaucoma and EXS samples in comparison to cataract controls (P < 0.05). CONCLUSION: TIMP-2 is elevated in glaucomatous process over MMP-2, which support and further extend the conjuncture that the ECM accumulation rather than degradation predominates in the pathogenesis of POAG and EXG.

Aged↗