Effects of graded doses of propofol for anesthesia induction on cardiovascular parameters and intraocular pressures in normal dogs.

OBJECTIVE: To determine the effects of graded doses of propofol on cardiovascular parameters and intraocular pressures (IOP) in normal dogs. STUDY DESIGN: Prospective, randomized, modified Latin square, cross-over experimental study. ANIMALS: Eleven adult random-source dogs weighing 20.2 +/- 5.7 kg. METHODS: There were three treatment groups: propofol 8 mg kg(-1) intravenous (i.v.) until loss of jaw tone (Group P), propofol until loss of jaw tone +20% (Group P20), and propofol until loss of jaw tone +50% (Group P50). Atracurium 0.1 mg kg(-1) i.v. was administered in all treatments immediately after the propofol. All dogs received the three treatments in a randomized order, with at least a one week interval between treatments. Direct arterial blood pressure and IOP by applanation tonometry were obtained at baseline, after 5 minutes of pre-oxygenation (before induction), before, and after intubation. Blood gas samples were obtained at baseline, after pre-oxygenation, and before intubation. RESULTS: There was no significant difference in IOP readings at any time point among groups. The IOP was significantly higher before intubation versus before induction in all three groups. There was a significantly smaller change in systolic, mean (MAP), and diastolic (DAP) arterial pressures in the P50 group compared with the P group after intubation. There was a significantly smaller change in MAP and DAP in the P50 group compared with the P20 group after intubation. The increase in CO(2) from before induction to before intubation was significantly greater in the P50 group than in the P or P20 groups. CONCLUSIONS AND CLINICAL RELEVANCE: Graded doses of propofol did not affect the increase in IOP observed with propofol induction in normal dogs. Higher doses of propofol are of no apparent additional benefit in animals who cannot tolerate an abrupt increase in IOP but may be of benefit in dogs who cannot tolerate an abrupt increase in blood pressure accompanying orotracheal intubation.

Identification of ocular matrix metalloproteinases present within the aqueous humor and iridocorneal drainage angle tissue of normal and glaucomatous canine eyes.

PURPOSE: The purpose of this study was to identify the most active matrix metalloproteinases (MMP) within the aqueous humor and iridocorneal angle tissue involved in the normal canine eye, and to compare these results to the MMP activity in dogs with glaucoma. ANIMAL STUDIED: Aqueous humor samples from 32 normal eyes and 26 glaucomatous eyes were obtained through aqueous centesis and analyzed for MMP activity. Iridocorneal angle tissue from 16 enucleated normal canine eyes and 5 enucleated glaucomatous eyes were dissected and homogenized into solution. PROCEDURE: Bradford total protein assays were determined for aqueous humor samples and iridocorneal angle tissue samples. Substrate gelatin zymography was performed using 0.2 microL volumes of an MMP-2/MMP-9 control, 2 microL volumes of aqueous humor samples, and 10 microg weights of total protein from iridocorneal angle tissue. The presence of MMP gel bands were identified visually and measured quantitatively by densitometry technique. A statistical analysis was performed on the data using Student's t-test, multiple logistic Wald's chi-squared regression, Pearson correlations, and repeated measures analysis. RESULTS: Within the aqueous humor of canine eyes, MMP-2 latent form was found to be the most relevant MMP. The quantity of latent MMP-2 within the aqueous humor of the glaucoma samples was significantly increased compared to the normal aqueous samples (P < 0.0001). Glaucoma occurrence was associated with elevated aqueous humor latent MMP-2 (P = 0.0002). Within the canine iridocorneal angle tissue, MMP-9 latent form and MMP-2 active form were found to be the most relevant MMPs. MMP-2 active form was found to be significantly increased in the glaucoma tissue samples when compared to the normal tissue samples (P = 0.0044). MMP-9 latent form was also found to be significantly increased in glaucomatous tissue when compared to the normal eyes (P = 0.0002). Tissue MMP-9 latent form was found to be associated with glaucoma status (P = 0.042). CONCLUSION: Glaucoma aqueous humor samples expressed a statistically increased latent MMP-2 when compared to normal eyes. Iridocorneal angle tissue from glaucomatous eyes expressed a statistically significant increase in active MMP-2 and latent MMP-9 when compared to normal eyes. These data demonstrate that there is an association between elevated levels of intraocular MMP-2 and MMP-9 and the presence of glaucoma.

In vitro efficacy of a buffered chelating solution as an antimicrobial potentiator for antifungal drugs against fungal pathogens obtained from horses with mycotic keratitis.

OBJECTIVE: To determine whether a novel third-generation chelating agent (8 mM disodium EDTA dehydrate and 20 mM 2-amino-2-hydroxymethyl-1, 3-propanediol) would act as an antimicrobial potentiator to enhance in vitro activity of antifungal medications against fungal isolates obtained from horses with mycotic keratitis. SAMPLE POPULATION: Fungal isolates (3 Aspergillus isolates, 5 Fusarium isolates, 1 Penicillium isolate, 1 Cladosporium isolate, and 1 Curvularia isolate) obtained from horses with mycotic keratitis and 2 quality-control strains obtained from the American Type Culture Collection (ATCC; Candida albicans ATCC 90028 and Paecilomyces variotii ATCC 36257). PROCEDURE: Minimum inhibitory concentrations (MICs) against fungal isolates for 4 antifungal drugs (miconazole, ketoconazole, itraconazole, and natamycin) were compared with MICs against fungal isolates for the combinations of each of the 4 antifungal drugs and the chelating agent. The Clinical and Laboratory Standards Institute microdilution assay method was performed by use of reference-grade antifungal powders against the fungal isolates and quality-control strains of fungi. RESULTS: Values for the MIC at which the antifungal drugs decreased the growth of an organism by 50% (MIC50) and 90% (MIC90) were decreased for the control strains and ophthalmic fungal isolates by 50% to 100% when the drugs were used in combination with the chelating agent at a concentration of up to 540 microg/mL. CONCLUSIONS AND CLINICAL RELEVANCE: The chelating agent increased in vitro activity of antifungal drugs against common fungal pathogens isolated from eyes of horses with mycotic keratitis.