Synovial fluid changes in induced infectious arthritis in calves

The objective was to develop an experimental model of septic arthritis in calves and to evaluate the effect of treatment on cytologic and bacteriologic variables of synovial fluid. The right tarsus of 7 healthy Holstein bull calves were inoculated with 10(8) colony-forming units of viable Escherichia coli of a pap-positive strain (day 1). On day 2, joint lavage was performed and antibiotic treatment was instituted. Cytologic examinations, bacterial cultures, and pap factor determinations by polymerase chain reaction (PCR) were performed on synovial fluid samples that were collected daily until day 4, then every 4 days until day 24. Results of physical examination, the severity of lameness, and swelling were recorded. Clinical signs of septic arthritis appeared on day 2 and persisted until day 9 for all calves. Bacterial cultures from all calves were positive for E. coli on day 2, and remained positive until day 3 for 1 calf and until day 4 for 5 calves. In addition, PCR results were positive for all calves, with 6 positive through day 3 and 1 positive through day 4, after which a positive result was again obtained on day 24. Synovial fluid neutrophil counts and white blood cell counts were significantly increased on days 2-4; however, synovial total protein concentrations were increased (P < .05) throughout the experiment in comparison to day 1. Results of all bacterial cultures were negative on day 8, although clinicopathologic signs of inflammation persisted until day 20. This model successfully induced acute septic arthritis in calves. Rapid recovery occurred within 1 week when an appropriate treatment was instituted early in the course of the disease.     

Relative expression of matrix metalloproteinase-2 and -9 in synovial fluid from healthy calves and calves with experimentally induced septic arthritis

OBJECTIVE: To identify changes over time in relative expression of matrix metalloproteinase-2 (MMP-2) and -9 (MMP-9) in synovial fluid from healthy calves and calves with experimentally induced septic arthritis. ANIMALS: 12 Holstein calves. PROCEDURES: In 7 calves, Escherichia coli was injected in the right tarsal joint on day 1. Joint lavage was performed on day 2, and calves were treated with ceftiofur from days 2 through 21. Synovial fluid samples were collected on days 1 (before inoculation), 2 (before joint lavage), 3, 4, 8, 12, 16, 20, and 24. In the remaining 5 calves, joint lavage was performed on day 2 and synovial fluid samples were collected from the left tarsal joint. Relative expression of MMP-2 and MMP-9 was determined by means of gel zymography. RESULTS: On day 1, MMP-2 was detected in all synovial fluid samples but MMP-9 was not detected. In calves with septic arthritis, values for relative expression of MMP-9 monomer and dimer were significantly increased on days 2 through 20 and days 2 through 24, respectively, and relative expression of MMP-2 was significantly increased on days 3 through 20. There were significant linear associations between relative expression of the monomer and dimer forms of MMP-9 and between neutrophil count and relative expression of the MMP-9 monomer and dimer forms. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that relative expression of MMP-9 and MMP-2 increased in synovial fluid from calves with experimentally induced septic arthritis, with relative expression remaining high for several days after infection.     

Fast and local assessment of stilbene content in grapevine leaf by in vivo fluorometry

Stilbenes are grapevine phytoalexins. These highly fluorescent molecules are generally analyzed by HPLC. This technique allows accurate assay of different stilbenes, but it is destructive, time-consuming, and neglects their spatial distribution. This is why we have tested a new method based on in vivo fluorescence using commercial spectrofluorometers that allowed fast and local assessment of stilbene content in grapevine leaves. Stilbene synthesis in grapevine Vitis vinifera var. Muscat Ottonel leaves was induced by Plasmopara viticola inoculation or UV-C irradiation. Fluorescence was measured both from the abaxial and adaxial sides of leaves, then stilbene content was analyzed by HPLC. It varied from 0 in control leaves to 15 mg g-1 dry weight in UV-treated leaves. Highly significant regressions were found between HPLC stilbene content and the corresponding leaf UV-induced blue fluorescence. Thus, in vivo fluorescence is a good tool for a rapid study of stilbenes synthesis in grapevine leaves that can potentially be extended to other fluorescent molecules.     

Effect of repeated arthrocentesis and single joint lavage on cytologic evaluation of synovial fluid in 5 young calves

The objective of this study was to evaluate the effect of repeated arthrocentesis and a single joint lavage on cytologic variables of synovial fluid. The left tarsi of 5 healthy Holstein calves were selected for the study. Samples of synovial fluid were collected daily for 4 d, then every 4 d until day 24. On day 2, joint lavage was performed with lactated Ringer's solution in all the calves. Cytologic examinations, performed by the same clinical pathologist, included the determination of total protein concentration, total leukocyte count, and differential counts (of neutrophils, lymphocytes, and monocytes). The presence of lameness or swelling and other results of physical examination were recorded regularly during the study. No clinical signs of joint disease were observed during the study. Bacterial cultures of specimens collected on day 2 were negative for all the calves. All cytologic values but 1 peaked on day 2 and progressively returned to normal. In comparison with the results for day 1, the synovial fluid total leukocyte, neutrophil, and monocyte counts were significantly increased on days 2 and 3, and the total leukocyte and monocyte counts were also significantly increased on day 4. The monocyte and lymphocyte percentages were significantly decreased until day 4, whereas the neutrophil percentages were significantly increased until day 8. The total protein concentrations were significantly increased until day 3. There were no significant differences between values for specimens taken 4 d apart. This study demonstrated that, although arthrocentesis induces a moderate inflammatory response, the joints seem to rapidly adapt. A 4-d interval between arthrocenteses is suitable when studying cellular components of the synovial fluid. However, when arthrocentesis is repeated daily, a minimal interval of 8 d should be respected.