Fibronectin in the synovium of chronic inflammatory joint disease

Summary The localisation of fibronectin in the synovial membrane of rheumatoid arthritis (RA) and other chronic inflammatory joint diseases has been studied using a peroxidase-antiperoxidase immunohistochemical method. Synovia were studied from seven cases of seropositive RA three cases of seronegative RA, six cases of ankylosing spondylitis, four cases of Reiter's syndrome and five of psoriatic arthritis. Six were small biopsies and the remaining tissues were obtained at open surgery for orthopaedic procedures or biopsies.Fibronectin was demonstrated in all of the synovia examined and was present in intimal cells, synovial giant cells, the walls of small blood vessels, basement membrane of larger vessels and deposits of fibrin. No difference in this distribution of fibronectin was found in seropositive and seronegative RA, ankylosing spondylitis, Reiter's syndrome or psoriatic arthritis, neither was there any difference in the amount of fibronectin at various sites.     

A neurophysiological study of mirror movements in adults and children.

The mechanism underlying mirrored activity/movements in normal individuals is unknown. To investigate this, we studied 11 adults and 39 children who performed sequential finger-thumb opposition or repetitive index finger abduction. Surface electromyographic (EMG) activity recorded from the left and right first dorsal interosseous muscles (1DI) during unilateral sequential finger-thumb opposition (voluntarily activated muscle, 1DIvol) showed mirrored EMG activity (homologous muscle of the opposite hand, 1DImm) that decreased with increasing age. The time of onset of involuntary compared with voluntary EMG activity was variable but could start at the same time. A significant increase in E2 (transcortical component) size of the cutaneomuscular reflex recorded from the 1DImm indicated increased excitability of the motor cortex ipsilateral to the 1DIvol during active index finger abduction compared with the 1DIvol relaxed. Transcranial magnetic stimulation, using the Bistim technique, indicated that the transcallosal inhibitory pathway in children may not operate in the same way as in the adult. Cross-correlation analysis did not detect shared synaptic input to motoneuron pools innervating homologous left and right hand muscles. We conclude that the mirrored movements/activity observed in healthy adults and children are produced by simultaneous activation of crossed corticospinal pathways originating from both left and right motor cortices.