Modification of articular cartilage and subchondral bone pathology in an ovine meniscectomy model of osteoarthritis by avocado and soya unsaponifiables (ASU).

OBJECTIVE: To examine the effect of an oral preparation of avocado and soya unsaponifiables (ASU) on the development of joint pathology in an ovine model of osteoarthritis (OA), using computer-assisted histomorphometric methods. DESIGN: OA was induced in ovine knee joints by bilateral lateral meniscectomy (N=32). ASU (900 mg/weekday) was given orally to half the group (MenX+ASU), the remainder receiving placebo (MenX). Sixteen animals were used as non-operated controls (NOC). At 3 and 6 months post-meniscectomy, histological sections from the medial and lateral femoral condyles (MFC, LFC), tibial plateaux (MTP, LTP) and trochlear groove (TG) were prepared from all joints. Sections were scored using traditional histopathological scales, and computerized image analysis, measuring total cartilage area, uncalcified cartilage (UCC) and subchondral bone plate (SCP) thickness, and intensity of articular cartilage toluidine blue staining (mean greyscale intensity, black=255) as an index of proteoglycan (PG) content. RESULTS: Computerized image analysis showed significant histological differences not detectable by traditional scoring methods. ASU-treated animals at 6 months showed reduced loss of toluidine blue stain in the MTP (P=0.015) and LTP (P=0.001), and significantly greater staining in the TG than either placebo or NOC groups (P=0.011). UCC thickness increased after meniscectomy, but tended to be highest in ASU-treated animals, significantly so in the middle zone of the LFC (MenX+ASU: 1.03+/-0.21mm vs MenX: 0.79+/-0.14 mm, P=0.018; NOC: 0.77+/-0.17 mm). Lateral compartment SCP thickness increased post-meniscectomy but was increased significantly less in the inner zone of the LTP in ASU-treated sheep (MenX+ASU: 1.37+/-0. 23 mm vs MenX: 1.68+/-0.28 mm, P=0.033; NOC=1.22+/-0.33 mm). CONCLUSIONS: In this model ASU treatment following meniscectomy appeared to confer a subtle but statistically significant protective effect on articular cartilage. Although the drug failed to prevent focal cartilage lesions, characteristic of this model, histomorphometric analysis demonstrated greater PG content and UCC thickness in adjacent joint regions of ASU-treated animals. In addition, a statistically significant reduction of subchondral bone sclerosis was noted in the LTP region of the drug-treated group. An anabolic effect on chondrocytes, resulting in the stimulation of matrix production in regions distant to the insult, was also suggested by the data. These findings support other studies which have proposed that ASU may exhibit disease-modifying anti-OA activity.

Systemic use of pentosan polysulphate in the treatment of osteoarthritis.

Forty dogs diagnosed as having chronic osteoarthritis took part in a double-blind clinical dose-response study using the antiarthritic agent pentosan polysulphate (PPS). After complete physical examination to ensure good general health, dogs received four subcutaneous injections at intervals of one week 0, 1, 3 or 5 mg/kg PPS from code-numbered bottles. At weekly intervals and four weeks after the last injection, weakness, stiffness, pain on joint manipulation, willingness to exercise, body condition and overall response were scored. There were no differences between groups in baseline data, but dogs receiving PPS had a favourable response compared to dogs receiving a placebo for lameness, body condition, pain on joint manipulation and willingness to exercise. The 3 mg/kg dose rate gave the best improvement, the 1 mg/kg dose was partially effective and the 5 mg/kg group was least effective. The use of PPS at a dose rate of 3 mg/kg for the treatment of clinical osteoarthritis in dogs is indicated by our study.

Treatment of canine nictitans plasmacytic conjunctivitis with 0.2 per cent cyclosporin ointment.

Nictitans plasmacytic conjunctivitis, commonly referred to as plasma cell infiltrate of the nictitans or plasmoma, was diagnosed in 12 dogs (23 eyes) on the basis of clinical signs and nictitans conjunctival biopsy specimens. These dogs underwent a clinical therapeutic trial with twice daily 0.2 per cent cyclosporin ophthalmic ointment. Response to therapy was monitored over a six-week period and repeat biopsy specimens were then taken. Significant (P < 0.05) reductions between pre- and post trial scores were recorded for: mucopurulent ocular discharge quantity; degree of bulbar conjunctival hyperaemia; areas of nictitans hyperaemia, thickening and depigmentation. Schirmer tear test values significantly increased between the start and end of treatment. Biopsy specimens were subjected to selective detection procedures for plasma cells (methyl green-pyronin staining) and T lymphocytes (CD3 antigen labelling). Mean cell counts showed a significant reduction in plasma cell numbers, but the trend towards reduced T lymphocyte numbers was not significant.