Bacteriologic cure of experimental Pseudomonas keratitis.
Two long-term therapy trials with high concentrations of antibiotic were carried out to determine the duration of therapy required to achieve bacteriologic cure of experimental Pseudomonas keratitis in guinea pigs. In the first study, corneas still contained Pseudomonas after 4 days of continual topical therapy with either tobramycin 400 mg/ml, amikacin 250 mg/ml, ticarcillin 400 mg/ml, or carbenicillin 400 mg/ml. In an 11-day trial of topical therapy with tobramycin 20 mg/ml, 34 of 36 corneas grew no Pseudomonas after 6 or more days of therapy. The bacteriologic response to therapy in this model occurred in two phases. About 99.9% or more of the organisms in the cornea were killed in the first 24 hr of therapy. The numbers of bacteria remaining in the cornea declined gradually over the next several days until the corneas were sterile. Optimal antibiotic therapy may include two stages: initial intensive therapy with high concentrations of antibiotic applied frequently to achieve a large rapid decrease in numbers of organisms in the cornea, followed by prolonged, less intensive therapy to eradicate organisms and prevent relapse. (+info)
Latrunculin-A causes mydriasis and cycloplegia in the cynomolgus monkey.
PURPOSE: To determine the effect of latrunculin (LAT)-A, which binds to G-actin and disassembles actin filaments, on the pupil, accommodation, and isolated ciliary muscle (CM) contraction in monkeys. METHODS: Pupil diameter (vernier calipers) and refraction (coincidence refractometry) were measured every 15 minutes from 0.75 to 3.5 hours after topical LAT-A 42 microg (approximately 10 microM in the anterior chamber [AC]). Refraction was measured every 5 minutes from 0.5 to 1.5 hours after intracameral injection of 10 microl of 50 microM LAT-A (approximately 5 microM in AC), with intramuscular infusion of 1.5 mg/kg pilocarpine HCl (PILO) during the first 15 minutes of measurements. Pupil diameter was measured at 1 and 2 hours, and refraction was measured every 5 minutes from 1 to 2 hours, after intravitreal injection of 20 microl of 1.25 mM LAT-A (approximately 10 microM in vitreous), with intramuscular infusion of 1.5 mg/kg PILO during the first 15 minutes of measurements (all after topical 2.5% phenylephrine), and contractile response of isolated CM strips, obtained <1 hour postmortem and mounted in a perfusion apparatus, to 10 microM PILO +/- LAT-A was measured at various concentrations. RESULTS: Topical LAT-A of 42 microg dilated the pupil without affecting refraction. Intracameral LAT-A of 5 microM inhibited miotic and accommodative responses to intramuscular PILO. Intravitreal LAT-A of 10 microM had no effect on accommodative or miotic responses to intramuscular PILO. LAT-A dose-dependently relaxed the PILO-contracted CM by up to 50% at 3 microM in both the longitudinal and circular vectors. CONCLUSIONS: In monkeys, LAT-A causes mydriasis and cycloplegia, perhaps related to its known ability to disrupt the actin microfilament network and consequently to affect cell contractility and adhesion. Effects of LAT-A on the iris and CM may have significant physiological and clinical implications. (+info)
Latrunculin-A increases outflow facility in the monkey.
PURPOSE: To determine the effect of Latrunculin (LAT)-A, a macrolide that binds to G-actin, which leads to the disassembly of actin filaments, on shape, junctions, and the cytoskeleton of cultured bovine aortic endothelial cells (BAECs) and on outflow facility in living monkeys. METHODS: Latrunculin-A dose-time-response relationships in BAECs were determined by immunofluorescence and phase contrast light microscopy, facility by two-level constant pressure anterior chamber perfusion. RESULTS: In BAECs, LAT-A caused dose- and incubation time- dependent destruction of actin bundles, cell separation, and cell loss. Cell-cell adhesions were more sensitive than focal contacts. Recovery was also dose- and time-dependent. In monkeys, exchange intracameral infusion and topical application of LAT-A induced dose- and time-dependent several-fold facility increases. The facility increase was completely reversed within several hours after drug removal. However, for at least 24 hours after a single topical LAT-A dose, perfusion with drug-free solution caused an accelerated increase in facility beyond that attributed to normal resistance washout. CONCLUSIONS: Pharmacological disorganization of the actin cytoskeleton in the trabecular meshwork by specific actin inhibitors like LAT-A may be a useful antiglaucoma strategy. (+info)
Effect of staurosporine on outflow facility in monkeys.
PURPOSE: To determine the effect of the serine-threonine kinase inhibitor staurosporine on outflow facility in living monkeys. METHODS: Total outflow facility was determined by two-level constant pressure perfusion of the anterior chamber bilaterally before and after intracameral infusion of staurosporine or vehicle in opposite eyes. RESULTS: Intracameral staurosporine dose-dependently doubled outflow facility, with 0.1 microM, 1 microM, and 10 microM being subthreshold, effective, and maximal doses, respectively. At 50 microM, intracameral staurosporine was less effective than 10 microM on facility and induced corneal toxicity. CONCLUSIONS: The broad-spectrum protein kinase inhibitor staurosporine increases outflow facility in living monkeys, perhaps by affecting the trabecular meshwork cytoskeleton. (+info)
Population pharmacokinetics of 2% topical dorzolamide in the aqueous humor of humans.
PURPOSE: To evaluate the concentration and kinetics of dorzolamide in the aqueous humor after its topical application. METHODS: Samples of aqueous humor were collected at the beginning of routine cataract surgery at defined intervals after topical application of a 2% solution of dorzolamide. After deep-frozen storage of the samples, drug extraction was achieved with a mixture of solvents. Quantification was carried out by high-performance liquid chromatography on a reversed-phase column. RESULTS: Peak concentrations of dorzolamide in aqueous humor were reached approximately 2 hours after application with 1000 ng/ml. Average values were approximately 1000 to 700 ng/ml after 4 to 6 hours and approximately 200 ng/ml after 12 hours. Mean half-life of absorption was 1.2 hours and for elimination 3.0 hours. CONCLUSIONS: Pharmacokinetics of dorzolamide in the aqueous humor of humans are in comparable dimensions as previously reported in experimental trials in pigmented rabbits. There is a clear linear absorption and elimination kinetic, which is demonstrated using the Bateman function. A better knowledge of the distribution and kinetics of dorzolamide will help to explain its reported effects on intraocular hemodynamics, distinct from its intraocular pressure lowering effect. (+info)
The use of topical aqueous suppressants in the prevention of postoperative intraocular pressure elevation following pars plana vitrectomy with long-acting gas tamponade.
PURPOSE: To determine if topical aqueous suppressant therapy applied after pars plana vitrectomy (PPV) with gas tamponade successfully prevents postoperative elevation of intraocular pressure (IOP). METHODS: A prospective, controlled study was performed on patients who met inclusion criteria and underwent PPV with gas tamponade (SF6 18%-20% or C3F8 12%-16%) over a 1-year period. Treatment eyes received topical aqueous suppressants at the end of surgery. Postoperative IOP checks were performed at 4 to 6 hours, 1 day, and 1 week. RESULTS: Twenty-one control (C) and 20 treatment (T) eyes met the inclusion criteria. The IOP (in mm Hg) measured at 4 to 6 hours (23.05 [C], 14.73 [T] and 1 day (23.24 [C], 17.28 [T]) postoperatively showed a statistically significant difference between the groups (P = .0038) at 4 to 6 hours, and a trend toward significance (P = .057) at 1 day. Eleven control and 3 treatment eyes had an IOP spike above 25 mm Hg at 4 to 6 hours or 1 day postoperatively (P = .02), and 6 control and 1 treatment eye had a postoperative IOP above 30 mm Hg. A pressure rise above 40 mm Hg was seen in 2 control eyes and no treatment eyes. CONCLUSIONS: Use of topical aqueous suppressants following PPV with long-acting gas tamponade is effective in preventing significant postoperative IOP elevation in a majority of cases. (+info)
Long-term ultrastructural changes in human corneas after tattooing with non-metallic substances.
AIM: To investigate the ultrastructural appearance and the deposition pattern of dye particles in long term non-metallic corneal tattooing. METHODS: Two tattooed human corneas were obtained by keratoplasty. One corneal button was fixed in Karnovsky's solution and the other in Trumps' solution. Both corneas were divided and processed for conventional light (LM) and transmission electron microscopy (TEM). Five additional formalin fixed corneas with tattoos were retrieved from paraffin for TEM. The time between tattoo and removal of the corneal button/enucleation ranged from 7 to 61 years. All seven corneas were examined using a Jeol JCXA733 microprobe for wave length dispersive analysis in order to exclude any presence of metallic salts in the tattooed area. RESULTS: Histologically, clumps of brown-blackish granules were present mainly in the mid stroma, but also in anterior and partially in the posterior half of the stroma. On TEM, numerous round and oval electron dense particles were seen in the cytoplasm of keratocytes arranged as clusters or large islands. The larger particles appeared black, while the smaller particles were grey. In well fixed tissue a unit membrane was observed around these clusters. No granules were detected in the extracellular matrix. CONCLUSIONS: Keratocytes can actively ingest and retain tattooing particles of non-metallic dyes within their cell membrane for very long periods of time. (+info)
Treatment of dry eye by autologous serum application in Sjogren's syndrome.
AIM: To evaluate the efficacy of autologous serum application for the treatment of dry eye in Sjogren's syndrome. METHODS: The stability of essential components (EGF, vitamin A, and TGF-beta) in preserved serum were examined following preservation at 4 degrees C and -20 degrees C. In a primary clinical trial, 12 patients with Sjogren's syndrome were treated with autologous serum (diluted to 20% with sterile saline) for 4 weeks, and vital staining of the ocular surface was compared before and after treatment. The effects of serum on mucin (MUC-1) expression were observed in cultured conjunctival epithelial cells in vitro. RESULTS: EGF, vitamin A, and TGF-beta were well preserved for up to 1 month in the refrigerator at 4 degrees C and up to 3 months in the freezer at -20 degrees C. Rose bengal and fluorescein scores improved significantly from the initial scores of 5.3 and 5.6 to 1.7 and 2.5 after 4 weeks, respectively. The additive effect of human serum for cultured conjunctival epithelial cells showed significant MUC-1 upregulation on the cell surface. CONCLUSION: Autologous serum application is a safe and efficient way to provide essential components to the ocular surface in the treatment of dry eye associated with Sjogren's syndrome. (+info)