The local mediators nitric oxide (NO) and prostaglandin E, (PGE ) play a role in the cascade of extracellular matrix breakdown in articular cartilage.In the present study the spontaneous production of NO and PGE, in explant cultures of equine synovial membrane and articular cartilage and their concentration over tjme n culture was investigated and correlated.Synovial membrane and articular cartilage was harvested from metacarpophalangeal jonts of 33 horses durlng arthroscopic surgery (n=4) or after being slaughtered/euthanised for reasons other than infectious or metabolic dlsease (n=29).Trssues were cultured as explant cuJtures in the presence of 4 ml Ham's F 12 medium, supplemented with streptomycin (100 pg/ml) and penicillin (100 U/ml) and incubated in a 5% CO2 and water saturated atmosphere for 8 days.Re sults showed that generally equine synovial membrane produced less NO than articular cartilage explant cultures with comparable wet weights/ml of media, but significantly more PGE, (P<0.05).The concentrations of both mediators were relatively stable over the first 4 days of culture, at least in the group of 25 mg wet wdghvml of media.In this group, there was a weak tendency noticed for NO to decrease, and PGE, to increase over time with day 4 being the intersection for both.Tissue cultures of articular cartilage with 12.5 mg wet weight/ml of culture media produced less reliable results, especially with NO measurements, which was thought to be associated with the sensitivity of the assay.lt is recommended to collect conditioned media for the measurements of NO and PGE, within the first 4 days of explant culture, since atter this time period culture effects may mask the results at least for NO measurements.Both mediators may be factors that play an impor tant role in the local med ation of ioint inflammations.
Subchondral cystic lesions (SCLs) from the medial femoral condyle (MFC) are a common problem in horses and are usually located on the weight-bearing surface of the joint and may be clinical or non-clinical in nature (Baxter 1996, McIlwraith 2002). They have been graded or grouped by previous investigators on the basis of radiographic appearance (White et al. 1988), location (Jeffcott and Kold 1982), as well as depth and lesion size (Howard et al. 1995). They have been variously described as subchondral bone cysts, subchondral cystic lesions, or osseous cyst-like lesions (McIlwraith 1998). They have also had careful comparison to subchondral bone cysts secondary to osteoarthrosis in humans (von Rechenberg et al. 1998). C. W. McIllwarith
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