In isolated normal rat jejunum, platelet-activating factor (PAF) induced a dose-dependent increase in short-circuit current (Isc) that was reduced in chloride-free buffer and inhibited by the Cl- channel blocker, diphenylamine-2-carboxylate. An immediate rise in Isc (early phase) occurred that fell to a new elevated base line by 15 min (late phase). These responses to PAF occurred only when experiments were conducted at or before approximately 9 A.M. Early phase responses were blocked by the specific PAF antagonists, BN52021 and WEB2086, and were inhibited by the neurotoxin, tetrodotoxin. Early and late phases were also reduced by cyclooxygenase inhibitors and by doxantrazole, a mast cell stabilizing drug. However, histamine and serotonin antagonists were ineffective. We conclude that PAF causes changes in ion transport that include Cl- secretion and acts on the epithelium possibly via an intermediate cell and enteric nerves. In addition, known PAF receptors are involved in one component of the response that appears to follow a circadian rhythm.

Rheumatoid-like lesions developed in 9 of 25 (36%) Old English rabbits drinking cow’s milk for 12 weeks. The incidence of lesions in male and female animals was similar. The majority of rabbits drinking cow’s milk developed increased numbers of nucleated cells and raised percentages of T lymphocytes in their synovial fluids, compared to control rabbits. The cell counts and T cell percentages correlated with the severity of the histological lesions. No evidence of glomerulonephritis was observed in any of the experimental animals.

SUMMARY Rabbits receiving repeated intravenous injections of killed bacteria (Escherichia coli or Bacillus subtilis) developed IgM rheumatoid factor which reacted with autologous heataggregated IgG. In addition, 5/7 'Old English' and 7/8 'Sandy Lop' rabbits receiving killed E.coli developed rheumatoid-like synovial lesions. 'Old English' rabbits developed lesions of a more severe nature. Three of eight 'Sandy Lop' rabbits injected with killed B.subtilis had high levels of rheumatoid factor but only mild joint lesions.Key words: arthritis, autologous heat-aggregated IgG, Escherichia coli, Bacillus subtilis.Rheumatoid factor-like substances (RFLS) have been described in rabbits after the administration of a variety of bacterial' or protein23 antigens. However, joint lesions were not reported in any of these models. In this paper we report the induction of both rheumatoid factor (RF), reacting with autologous heat-aggregated IgG, and rheumatoid-like synovial lesions in rabbits injected with either killed Escherichia coli or Bacillus subtilis. subtilis (B. subtilis NCTC 3610) were grown in 1 litre volumes in 3 litre Erlenmeyer flasks at 37°C for 48 hours in brain/heart infusion broth (Difco). Formalin (final concentration of 0-6%) was then added to the broth cultures, which were left for 24 h at 20°C in order to kill the bacteria. The bacteria were harvested by centrifugation, and the deposit was washed three times in phosphate-buffered saline (PBS). The bacteria were resuspended in PBS and standardised by opacity testing to 6 x 109 bacteria/ ml. The bacteria were finally sterilised by steaming for 1 h and thereafter stored at -20°C. Control 'Old English' and 'Sandy Lop' rabbits did not receive any bacteria. Rabbits were bled at monthly intervals from the marginal vein of the ear. Sera were frozen and stored at -20°C. ASSESSMENT OF ARTHRITIS

No abstract

No abstract