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Abstract

Objective

To determine whether differences exist in induction and quantity of tumor necrosis factor α (TNF-α), interleukin (IL)1ß, and IL-10 mRNA transcripts when mouse J774A.1 macrophages are infected with Listeria monocytogenes, including 2 isolates originating from channel catfish, the wild-type virulent (EGD) strain, and a nonhemolytic strain (ATCC 15313).

Samples

Listeria monocytogenes isolates from kidneys or fillets of channel catfish were used to stimulate cytokine production from mouse macrophages. The RNA from the infected macrophages was collected.

Procedure

Four hours after infection with L monocytogenes, total cellular RNA was extracted from the J774A.1 cells and reversed transcribed to cDNA, which was amplified, using specific primers for TNF- α, IL-1ß, or IL-10. The specific amplified DNA fragments were detected on polyacrylamide gels and quantified, using a reverse transcription polymerase chain reaction (PCR)-mediated ELISA.

Results

The wild-type hemolytic EGD strain and the 2 hemolytic catfish isolates of L monocytogenes induced higher amounts of TNF-α-, IL-1ß-, and IL-10- specific mRNA in J774A.1 cells than did the nonhemolytic strain.

Conclusions

Hemolysin-associated induction of TNF-α, IL-1ß, and IL-10 cytokines may be related to survival and replication of L monocytogenes in macrophages. It also suggests that the PCR-mediated ELISA procedure is a sensitive test to quantify cytokines from cell cultures. (Am J Vet Res 1998;59:717-721)

Free access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the changes in concentrations of matrix metalloproteinase (MMP)-2 and MMP-9 in the precorneal tear film of dogs with Pseudomonas aeruginosa–associated keratitis during corneal healing and stromal remodeling.

Animals—10 dogs with unilateral P aeruginosa–associated keratitis and 10 clinically normal dogs.

Procedures—Precorneal tear film samples were collected from both eyes of 10 dogs with unilateral P aeruginosa–associated keratitis on the day of admission to the hospital and then at various time points until complete healing of the cornea was achieved. Precorneal tear film samples were also collected from both eyes of 10 clinically normal adult dogs (control group). Concentrations of MMP-2 and MMP-9 in precorneal tear film samples from each group were determined via gelatin zymography for comparison.

Results—The proteolytic processes in the ulcerated eyes decreased as corneal healing progressed. On the day of admission, concentrations of latent and active forms of MMP-2 and MMP-9 in ulcerated eyes were significantly higher than values in the contralateral unaffected eyes in dogs with P aeruginosa–associated keratitis; concentrations of latent MMP-2 and MMP-9 were also greater than control group values. Concentrations of latent and active forms of MMP-2 and MMP-9 in the healed eyes of dogs with P aeruginosa–associated keratitis were significantly lower than concentrations in the ulcerated eyes on the day of admission.

Conclusions and Clinical Relevance—Results suggest that reduction of precorneal tear film concentrations of MMPs by use of proteinase inhibitors may be effective in the treatment of dogs with P aeruginosa–associated keratitis.

Full access
in American Journal of Veterinary Research

Abstract

Objective

To characterize Listeria monocytogenes from tissues of channel catfish for their ability to cause hemolysis and grow intracellularly in mouse macrophages.

Samples

15 isolates from processed fillets and 15 isolates from the brain, spleen, and kidneys.

Procedure

Serotype and hemolytic activity of L monocytogenes isolates were evaluated, using plate agglutination and CAMP tests, respectively. Invasiveness of L monocytogenes was determined by inoculating each strain or isolate on J774A.1 macrophage cells. Infected cells were incubated for 0 or 3 hours and lysed; then 100 μΙ of the lysate was plated onto a brain heart infusion agar plate. Colony counts for each strain or isolate were analyzed statistically.

Results

Of 30 isolates, 19 were serotype 1 and 11 were serotype 4. Mouse J774A.1 macrophages were inoculated with catfish isolates, a wild-type (EGD) or a nonhemolytic strain of L monocytogenes. Seventy-three percent (11/15) of isolates originating from catfish organs and 100% (15/15) of isolates originating from fillets were not significantly different from the wild-type EGD strain. The nonhemolytic L monocytogenes strain used as a negative control failed to replicate. Intracellular growth of all L monocytogenes isolates decreased after an additional 3-hour incubation period with medium containing 50 μg/ml of gentamicin.

Conclusions

Similar to the wild-type EGD strain, most channel catfish L monocytogenes isolates were hemolytic, serotype 1 or 4, and were invasive for mouse J774A.1 macrophages.

Clinical Relevance

L monocytogenes growth in mouse macrophages may serve as an in vitro model for determining virulence of isolates from food products or environments. (Am J Vet Res 1998;59:1125-1128)

Free access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

The objective of this study was to develop a robust machine-learning approach for efficient detection and grading of sesamoiditis in horses using radiographs, specifically in data-limited conditions.

SAMPLE

A dataset of 255 dorsolateral-palmaromedial oblique (DLPMO) and dorsomedial-palmarolateral oblique (DMPLO) equine radiographs were retrospectively acquired from Hagyard Equine Medical Institute. These images were anonymized and classified into 3 categories of sesamoiditis severity (normal, mild, and moderate).

METHODS

This study was conducted from February 1, 2023, to August 31, 2023. Two RetinaNet models were used in a cascaded manner, with a self-attention module incorporated into the second RetinaNet's classification subnetwork. The first RetinaNet localized the sesamoid bone in the radiographs, while the second RetinaNet graded the severity of sesamoiditis based on the localized region. Model performance was evaluated using the confusion matrix and average precision (AP).

RESULTS

The proposed model demonstrated a promising classification performance with 92.7% accuracy, surpassing the base RetinaNet model. It achieved a mean average precision (mAP) of 81.8%, indicating superior object detection ability. Notably, performance metrics for each severity category showed significant improvement.

CLINICAL RELEVANCE

The proposed deep learning-based method can accurately localize the position of sesamoid bones and grade the severity of sesamoiditis on equine radiographs, providing corresponding confidence scores. This approach has the potential to be deployed in a clinical environment, improving the diagnostic interpretation of metacarpophalangeal (fetlock) joint radiographs in horses. Furthermore, by expanding the training dataset, the model may learn to assist in the diagnosis of pathologies in other skeletal regions of the horse.

Open access
in American Journal of Veterinary Research

Abstract

In collaboration with the American College of Veterinary Radiology

Open access
in Journal of the American Veterinary Medical Association