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At least 667 records · Page 37Linked to original sources
PubMed1984

Piperacillin levels in human tears and aqueous humor.

Thirty patients scheduled to undergo elective intraocular surgery were each given 4 g of piperacillin intravenously. Specimens of serum, tears, and aqueous humor were collected from zero to nine hours after infusion and assayed for piperacillin content by high pressure liquid chromatography. In noninflamed eyes piperacillin sodium distributed into tears and aqueous humor in concentrations exceeding the minimum inhibitory concentration required for many gram-positive and gram-negative organisms. Higher levels of piperacillin were anticipated in patients with inflamed eyes who possessed an altered blood-aqueous barrier, and in patients receiving serial doses of this agent.

Adult↗
PubMed2003

[Antiviral therapy adjustment in corneal recipients using antibody testing in the aqueous humor].

INTRODUCTION: In corneal recipients with herpes infection, acyclovir given for 1 year postoperatively prevents viral reactivation and improves graft outcome. The indication for prophylactic antiviral therapy relies on the preoperative diagnosis of herpes. However, many patients present with corneal scars featuring sequelae of herpes without a proven history of herpes. Here we report the results of a prospective study of anti-herpes simplex virus (anti-HSV) and varicella zoster virus (VZV) antibody testing in the aqueous humor at the time of corneal transplantation to refine the indication of the antiviral treatment. MATERIAL AND METHODS: The study involved 33 keratitis corneal graft recipients, 21 of whom had documented herpes keratitis. A control group was made with 11 cataract patients. An anterior chamber puncture was performed just before surgery. The micro-ELISA test was done on both aqueous humor and serum, and local anti-HSV or VZV antibody synthesis was acknowledged if the ratio of antibody concentrations was above 4. RESULTS: Local antibody synthesis to HSV was detected in 22 cases, to VZV in 9 cases, to both HSV and VZV in 6 cases, and no synthesis in 8 cases. The sensitivity of the test was 65% in patients with a documented history of herpes (14 cases out of 21). Among non-herpetic patients, the test was positive in 9 patients, who thus benefited from postoperative antiviral therapy. No viral reactivation was encountered after a minimum follow-up of 1 year. CONCLUSIONS: Antibody testing in the aqueous humor at the time of keratoplasty is a convenient, inexpensive diagnostic tool in corneal recipients. It provides useful information before prescribing a long and expensive postoperative antiviral therapy.

Acyclovir↗
PubMed2004

Secretoneurin in the human aqueous humor and the absence of an effect of frequently used eye drops on the levels.

Secretoneurin (SN) was detected in the aqueous humor (AH) of patients treated topically with tobramycine eye drops alone or tobramycine and cyclosporine A, tobramycine and diclofenac or tobramycine and rimexolone. The levels of the peptide were found to be higher in the uninflamed human than in the rabbit aqueous humor which may be the result of species differences and/or age-related circumstances. Furthermore, they are approximately one hundred times higher than those of classical neuropeptides indicating release from nerve fibers and/or secretion from non-pigmented ciliary epithelium cells. Despite a slight tendency by rimexolone to decrease the levels, there was no significant effect seen for either of the drops. It must be considered that aminoglycosides are known to have toxic side effects and that they can influence the levels of SN which may be not diminished by low topical doses of corticosteroids or nonsteroidal antiinflammatory drugs. The high levels of the peptide are of relevance and may indicate a significant role of secretoneurin in the anterior segment of the eye. This should encourage performing functional studies.

Adult↗
PubMed2002

Time dependent effects of sympathetic denervation on aqueous humor dynamics and choroidal blood flow in rabbits.

PURPOSE: This study investigates the time-dependent effects of superior cervical ganglionectomy (SCGx) on aqueous humor dynamics and ocular blood flow in rabbits. METHODS: Measurements were made at various times between 24 hours and 12 months after SCGx. Intraocular pressure (IOP) was measured by pneumatonometry, aqueous flow by fluorophotometry and outflow facility by tonography. Uveoscleral outflow was determined by an intracameral tracer infusion technique and blood flow to the choroid was evaluated with fluorescent microspheres. Values in denervated eyes were compared with the contralateral, normally-innervated eyes using a paired Student's two-tailed t-test. RESULTS: At 24 hours after SCGx, IOP in denervated eyes was less than in normally-innervated eyes (14.6 +/- 0.8 vs 20.1 +/- 1.5 mmHg, 27%, p < 0.002). At one month, IOPs were not different between eyes. Compared with normally-innervated eyes at 10-12 months, IOP in denervated eyes was greater (20.4 +/- 0.7 vs 17.2 +/- 0.9 mmHg, 19%, p < 0.001), outflow facility was less (0.15 +/- 0.02 vs 0.21 +/- 0.01 microl/min/mmHg, 29%, p < 0.01) and blood flow to the choroid was less (12.1 +/- 5.0 vs 16.2 +/- 6.0 ml/min/gm tissue, 25%, p < 0.05). Aqueous humor flow was not significantly altered by SCGx at any time. CONCLUSIONS: The reduction in IOP at 24 hours after SCGx was not due to any change in aqueous flow or uveoscleral outflow (current study) but rather to an increase in outflow facility (previous studies). At 10-12 months, IOP was elevated because outflow facility was significantly reduced. The reduction in choroidal blood flow at 10-12 months may have occurred because of the increased IOP.

Animals↗
PubMed1980

[Diagnostic values of quantitative serological tests of the aqueous humor in ocular toxoplasmosis. A report on 180 cases (author's transl)].

A simultaneous study of 180 recent samples of serum and aqueous humor, taken to study serological factors in cases of toxoplasmosis, demonstrated the production of intra-ocular antibodies in about 1 out of 2 cases (70 cases out of 145) of posterior uveitis. This confirms the value of calculating Witmer-Desmonts "C" coefficient for the diagnosis of the affection, as well as the careful evaluation of its different parameters; serum dye-test, and globulin levels in the aqueous humor nore particularly.

Anterior Chamber↗
PubMed1982

Hypotony and aqueous humor dynamics in myotonic dystrophy.

A group of 26 subjects with myotonic dystrophy were studied with fluorophotometry to evaluate the relationship between aqueous humor dynamics and the hypotony found in this disorder. All 26 received topical fluorescein to determine the anterior chamber elimination coefficient; five received systemic fluorescein to evaluate the integrity of the blood-aqueous barrier. The group has a mean intraocular pressure of 7.1 mm Hg. The rate of clearance of fluorescein from the anterior chamber and the cornea-to-anterior chamber transfer coefficient for fluorescein were normal. An abnormally high level of fluorescence, three times normal, was observed in the anterior chambers of the myotonic subjects after oral administration of fluorescein. This finding could not be attributed to abnormal absorption and elimination of fluorescein or to abnormal plasma binding. This finding indicates that there is a defect in the blood-ocular barrier to fluorescein in myotonic subjects. Thus conclusions regarding aqueous humor flow cannot be made from the rate of clearance of topically applied fluorescein in myotonic subjects, since the clearance due to diffusion may represent a significantly large fraction of the total clearance.

Adolescent↗
PubMed1993

Indomethacin reduces substance P levels in human ocular aqueous humor.

Substance P immunoreactivity was measured by radioimmunoassay in aqueous humor samples of patients treated 13 h earlier with gentamicin, indomethacin or timolol. The indomethacin-treated group showed significantly decreased levels of substance P. The indomethacin effect is due to inhibition of the synthesis of arachidonic acid metabolites or involves non-specific mechanisms. It is suggested that suppression of substance P release may contribute to therapeutic effects of indomethacin in the human eye in conditions such as surgical miosis.

Adult↗
PubMed1976

Macrophage migration inhibition factor activity in the aqueous humor during experimental corneal xenograft and allograft rejection.

Macrophage migration inhibition factor (MIF), a soluble mediator of delayed hypersensitivity, was assayed for in the aqueous humor of rabbits undergoing corneal graft rejection. Penetrating and interlamellar xenografts and interlamellar allografts were performed in rabbits, and aqueous humor early in the course of xenograft and allograft rejection, and MIF activity was present during the course of the active rejection. This activity returned to near normal after the active rejection resolved. No significant MIF activity could be measured during the nonspecific inflammations produced by alkali burns, multiple paracenteses, intracorneal clove oil, mechanical debriding of the endothelium.

Animals↗
PubMed2003

Aqueous humor dynamics and the iris.

Solutes concentration in the aqueous humor of the eye is highest near the ciliary processes in the posterior chamber (p.c.) and lowest near the trabecular meshwork in the anterior chamber (a.c.). The high osmotic gradient across the semipermeable iris causes it to easily move forward at this location and occasionally occlude the iridocorneal angle. Vector analysis of the forces generated by miosis helps explain on osmotic grounds why it reduces the intraocular pressure, while at the same time the analysis elucidates the reason for the higher frequency of angle closure glaucoma when the anterior chamber is shallow.

Aqueous Humor↗
PubMed1985

Fosfomycin levels in human aqueous humor after intravenous administration.

Following intravenous infusion of an 8 g single dose of the antibiotic agent fosfomycin, its penetration into human primary aqueous humor was investigated. 1-2 h after the start of infusion, peak values of 35 to 60 micrograms/ml were reached. These concentrations in the aqueous humor would inhibit a high percentage of gram-positive and gram-negative strains commonly causing bacterial endophthalmitis. The infusion of an 8 g dose of fosfomycin immediately preceding intraocular surgery thus constitutes effective peri-operative prophylaxis. Moreover, as a broad-spectrum antibiotic, fosfomycin is indicated as initial therapy in intraocular bacterial infections.

Aged↗
PubMed1998

Direct involvement of trabecular meshwork in the regulation of aqueous humor outflow.

Our new hypothesis for the regulation of aqueous humor outflow suggests that the trabecular meshwork is not a passive filter but an active contractile element contributing to the ciliary muscle traction affecting it. The trabecular meshwork contains contractile smooth-muscle-specific alpha-actin filaments, and its cells exhibit electrical properties typical for smooth muscle cells. Contractility measurements performed for the first time in isolated trabecular meshwork enable a functional comparison with ciliary muscle. Pharmacologic outflow regulation has been determined in isolated perfused anterior segments with intact trabecular meshwork and total absence of ciliary muscle. Substances that contracted isolated trabecular meshwork (e.g., pilocarpine) decreased the outflow rate, whereas relaxants (e.g., low-dose epinephrine) increased it. The concept of a functional antagonism between the trabecular meshwork and the ciliary muscle has to be considered.

Animals↗
PubMed1998

[Preparation of liposome encapsulated daunorbicine and determination of daunorubicine of aqueous humor in rabbit eyes].

PURPOSE: To investigate the method of determination the concentration of daunorubicine(DNR) and liposome encapsulated daunorubicine(LDNR) of aqueous humor in rabbit eyes. METHODS: After extracapsular lens extraction, 0.1 ml of 1 mg/ml DNA and LDNR were injected into the anterior chamber. At the 12, 24, 48 hours and 1 week after operation, the aqueous humor were aspirated to determine the concentration of DNR by high performance liquid chromatography(HPLC). RESULTS: At the 12, 24, 48 hours after operation, DNR were determined in all eyes, but at one week after operation, the DNR could only be detected in LDNR group. The concentration of DNR in LDNR group were higher than DNR group.

Animals↗
PubMed2004

Rapid determination of nimesulide in rabbit aqueous humor by liquid chromatography.

A rapid method was developed for quantification of nimesulide (methanesulfonamide, N-[4-nitro-2-phenoxyphenil]) in rabbit aqueous humor. The analyses were performed by high-performance liquid chromatography using a C(18) reversed-phase column (Ultracarb ODS) with UV detection at 300 nm. The mobile phase consisted of acetonitrile-water containing 1% triethylamine (TEA) adjusted to pH 3.2 with orthophosphoric acid. The retention time was 4.5 min. A simple pre-treatment with acetonitrile was used to deproteinize aqueous humor samples. The limit of quantitation was 50 ng/ml. The recovery was over 90%. The relationship between peak areas and concentration was linear over the range between 0.05 and 2.5 microg/ml, with r(2) values over 0.99. The assay provided good reproducibility and accuracy and proved to be suitable for pharmacokinetic studies of nimesulide.

Animals↗