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The effect of two different concentrations of povidone-iodine (PVI) solution, an antiseptic, on joint synovium was investigated. In Group I, 0.05 ml of 10% PVI was used, while in Group II, 0.05 ml of 2.5% of PVI was used. PVI solution was injected twice into both knee joints with one week interval. Ten rats were used as control and 70 rats as experimental.

In the two experimental groups four rats were sacrificed after 6, 12, 24 hours and three day and six rats at the end of the week after the second PVI injection. Synovial reaction was assessed histologically in both groups, based on the pathological parameters.

The results suggest that intra-articular injection of 10% and 2.5% PVI induces synovitis with focal ulceration which gradually subsides, and finally, the synovium becomes normal, though various degrees of subsynovial dense fibrosis complication arise.

Biomechanical evaluation of the subsynovial connective tissue (SSCT) provides insight into the causes of carpal tunnel syndrome. Studies of carpal tunnel mechanics have been performed using fresh-frozen cadaver tissue. Freezing can affect mechanical properties of some tissues, but its effect on SSCT is unknown. A total of 16 rabbit paws were harvested from eight New Zealand rabbits and subjected to mechanical testing consisting of three repeated tendon excursions in sets of three different excursion magnitudes. One paw from each animal was unfrozen. The contralateral paw was frozen and thawed before testing. Force, energy and stiffness of the first cycle of each set were evaluated, as were ratios of the second to first cycle for each parameter. Two-factor ANOVA with repeated measures over both factors was performed. No significant interactions between factors were found. There were no significant differences between fresh and frozen paws for any parameters, though there were significant differences between excursion amplitudes. The damage threshold was not different between fresh and frozen paws. This study demonstrated that freezing rabbit subsynovial connective tissue does not significantly change its mechanical properties. The same may be true for human cadaver tissues. Results of cadaver mechanical testing may not be influenced by this preservation technique.

We have recently reported that nerve growth factor (NGF) increases in the synovium of patients affected by rheumatoid arthritis and in the synovium of pharmacologically-induced arthritis in animal models. In the present study, we demonstrate that arthritic transgenic mice which carry and express the human TNF gene (Tgl97) also express elevated levels of NGF, and that subcutaneous injection of NGF-antibodies attenuates the loss of body weight caused by the developement of disease in these mice. Along with our previous findings,which show an increase in the level of NGF during the acute phase of other autoimmune diseases, these results suggest a role of NGF in these pathologies. The functional significance of NGF in rheumatoid arthritis (RA) is currently under study.