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  • Author or Editor: Ursula M. Dietrich x
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Abstract

Objective—To evaluate the effects of topical antifungal drugs and delivery vehicles on the morphology and proliferation rate of cultured equine keratocytes.

Study Population—16 corneas obtained from 8 apparently ophthalmologically normal horses < 0.5 hours after euthanasia for reasons unrelated to the study.

Procedures—Primary cultures of equine keratocytes were obtained from corneal stroma and were exposed to several concentrations of 3 commonly used, topically applied antifungals: natamycin, itraconazole, and miconazole. In addition, effects of drug delivery vehicles DMSO, benzalkonium chloride, and carboxymethylcellulose and a combination vehicle composed of polyethylene glycol, methylparaben, and propylparaben were also evaluated. Morphological changes and cellular proliferation were assessed 24, 48, and 72 hours after application.

Results—At the highest concentrations tested, all antifungals caused marked cellular morphological changes and inhibited proliferation. At low concentrations, natamycin and miconazole induced rounding, shrinking, and detaching of the cells with inhibition of cellular proliferation. Natamycin caused the most severe cellular changes. Itraconazole, at the low concentrations, caused minimal morphological changes and had a minimal effect on proliferation. All vehicles tested had significantly less effects on cellular morphology and proliferation when compared with the antifungals, except for the combination vehicle, which caused severe morphological changes and inhibited proliferation, even at low concentrations. The DMSO had minimal effects on cellular morphology and proliferation, even at high concentrations.

Conclusions and Clinical Relevance—Itraconazole had significantly less cytotoxic effects on equine keratocytes in culture than did natamycin or miconazole. Natamycin had severe cytotoxic effects in vitro.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether a novel third-generation chelating agent (8mM disodium EDTA dehydrate and 20mM 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 μg/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.

Full access
in American Journal of Veterinary Research

Abstract

Case Description—A 1-year-old sexually intact female Netherland dwarf rabbit was examined because of a 3-week history of signs of lethargy, decreased appetite, left unilateral exophthalmia, a previous draining sinus from a left maxillary facial abscess, and bilateral nasal discharge.

Clinical Findings—The rabbit weighed 1.0 kg (2.2 lb) and had a body condition score of 1.5/5. Physical examination revealed generalized muscle atrophy, bilateral mucopurulent nasal discharge, and severe left-sided exophthalmia. Diagnostic investigation revealed anemia, neutrophilia, severe dental disease, a superficial corneal ulcer of the left eye, and a retrobulbar abscess.

Treatment and Outcome—Stomatoscopy-aided dental trimming, tooth removal, and abscess debridement were performed. Antimicrobials were flushed into the tooth abscess cavity, and antimicrobial treatment was initiated on the basis of cytologic findings and results of bacterial culture and susceptibility testing.Two months after the initial surgery, minimal exophthalmia was evident and no further physical, radiographic, or ultrasonographic changes were evident.

Clinical Relevance—Stomatoscopy is a valuable technique that can facilitate diagnosis, treatment, and serial reevaluation of rabbits with dental disease.

Restricted access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To compare 2 techniques of inducing combined renal insufficiency and systemic hypertension in cats.

Animals—22 cats 6 to 12 months of age.

Procedure—Cats were randomly assigned to 1 of 3 groups. Control (C) group cats had 2 intact kidneys, remnant kidney (RK) group cats underwent unilateral partial renal infarction and contralateral nephrectomy, and remnant-wrap (W) group cats underwent unilateral partial renal infarction and partial abtation and wrapping of the contralateral kidney. Systemic arterial blood pressure (BP) was measured continuously by use of implanted radiotelemetric devices. Renal function was assessed via determination of glomerular filtration rate, measurement of serum creatinine and BUN concentrations, and determination of urine protein-to-creatinine ratio (UP/C). Serum aldosterone concentration and plasma renin activity were measured on day 75.

Results—Systolic BP was significantly higher in groups RK and W than in group C, and systolic BP was significantly higher in group W than in group RK. Serum aldosterone concentration and plasma renin activity were significantly higher in group W, compared with groups C and RK. Glomerular filtration rate was significantly lower in groups RK and W, compared with group C. Histologic indices of renal injury and UP/C were significantly higher in group W, compared with groups C and RK.

Conclusions and Clinical Relevance—Hypertensive renal insufficiency in group W was characterized by marked sustained systemic hypertension, decreased renal function, proteinuria, activation of the reninangiotensin-aldosterone axis, and renal structural injury. Results support the hypothesis that marked systemic hypertension, activation of the reninangiotensin- aldosterone axis, and proteinuria may damage the kidney of cats with preexisting renal insufficiency. ( Am J Vet Res 2004;65:1006–1013)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the effects of recombinant human interferon α-2b (rHuIFN-α2b) and recombinant feline interferon ω (rFeIFN-ω) on in vitro replication of feline herpesvirus (FHV)-1.

Sample Population—Cultures of Crandell-Rees feline kidney (CRFK) cells.

Procedures—CRFK cells were treated with rFeIFN-ω or rHuIFN-α2b at concentrations ranging from 100 to 500,000 U/mL. Cultures were then inoculated with FHV-1. Constant concentrations of interferon products were maintained throughout the study. Reductions in the number and size of plaques were used as indicators of antiviral activity. Six plaque reduction assays were performed in duplicate. A 3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide assay was used to detect cytotoxic effects of interferon. A 1-way ANOVA and Dunnett test were used to determine significant differences.

Results—Treatment with rFeIFN-ω at various concentrations resulted in significant reductions in the number of plaques (100,000 U/mL, 54.7%; and 500,000 U/mL, 59.8%) and in plaque size (100,000 U/mL, 47.5%; 250,000 U/mL, 81.0%; and 500,000 U/mL; 70.5%). Treatment with various concentrations of rHuIFN-α2b resulted in a significant reduction in plaque size (100,000 U/mL, 56.0%; 250,000 U/mL, 75.7%; and 500,000 U/mL, 69.0%). None of the tested concentrations of interferon caused significant cellular toxicosis.

Conclusions and Clinical Relevance—At some of the higher concentrations, the antiviral effect of rFeIFN-ω was greater than the antiviral effect of rHuIFN-α2b. Reduction in plaque size appeared to be a good indicator of the antiviral activity of interferon against FHV-1.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine the effects of treatment with and without adjuvant radiation therapy on recurrence of ocular and adnexal squamous cell carcinoma (SCC) at specific anatomic locations in horses.

Design—Retrospective study.

Animals—91 horses.

Procedures—Medical records of horses with histologically confirmed ocular and adnexal SCC evaluated from 1985 to 2002 were reviewed. Sex, breed, age, type of treatment, location, and recurrence of SCC were recorded. Two treatment groups determined by recurrence of SCCs treated with and without adjuvant radiation therapy were established.

Results—The anatomic site with the highest recurrence rate was the limbus (junction of the cornea and sclera) or bulbar conjunctiva (47.7%), independent of treatment group. There was a significant difference in recurrence rates of ocular and adnexal SCCs between the 2 treatment groups, independent of anatomic location. Recurrence rates of SCCs treated with and without adjuvant radiation therapy were 11.9% and 44.1%, respectively. Recurrence rates for SCCs of the eyelid, limbus or bulbar conjunctiva, and cornea treated with adjuvant radiation therapy were significantly different from those for SCCs treated without adjuvant radiation therapy. The most frequently represented anatomic site for ocular and adnexal SCCs was the eyelid (28.7%). Coat color, breed, and the interaction of age and breed had a significant effect on tumor recurrence regardless of treatment type and anatomic location.

Conclusions and Clinical Relevance—Results indicated that ocular and adnexal SCCs treated with adjuvant radiation therapy had a significantly lower recurrence rate, compared with SCCs treated without adjuvant radiation therapy, independent of anatomic location. (J Am Vet Med Assoc 2004;225:1733–1738)

Restricted access
in Journal of the American Veterinary Medical Association