Anticardiolipin antibodies (aCL) have been reported to occur in a wide variety of autoimmune and non-autoimmune disorders in adults. Our objective was to investigate the prevalence and isotype distribution of aCL and its relationship with the features of antiphospholipid syndrome (APS) in childhood rheumatic disorders. Between November 1995 and May 1996, all patients who visited our paediatric rheumatology clinic whose guardians signed a consent form participated in the study. The study population included 106 patients (36 systemic lupus erythematosus (SLE), 28 juvenile rheumatoid arthritis (JRA), 11 fibromyalgia, 7 sarcoidosis, 5 dermatomyositis, 3 rheumatic fever (RF), 3 vasculitis, 2 scleroderma, and 11 miscellaneous). aCL measurements were performed by enzyme linked immunoabsorbent assay (ELISA). All patients were carefully evaluated for symptoms and signs of APS. Eighteen of the 106 patients (17%) were tested positive for one or more of the three aCL isotypes. In SLE, aCL were found positive in 13 of 36 (37%); in JRA 2 of 28 (7%); in sarcoidosis 2 of 7; and in RF 1 of 3. aCL of IgG isotype were found positive in 16 patients (11 SLE, 2 sarcoidosis, 2 JRA, and 1 RF). This isotype was usually detected at low titers (16-24 GPL). aCL of IgM isotype were found positive in five patients (2 sarcoidosis, 2 SLE, 1 JRA), and aCL of IgA isotype were found positive in only three patients (2 SLE, 1 sarcoidosis). Clinical features of APS were rarely seen in our SLE population and were not associated with the presence of aCL. None of the patients in the other groups exhibited any clinical manifestations of APS. In conclusion, aCL were found in 37% of our childhood SLE patients as compared with only 7% in JRA. These were mostly aCL of IgG isotype of low titers and therefore were not associated with the main features of APS. Prospective studies with a larger sample size may be needed to ascertain the exact prevalence and clinical significance of aCL in childhood-onset SLE.

A retrovirus, human T cell lymphotropic virus type 1 (HTLV-1), is an essential but not a sufficient aetiologic factor for tropical spastic paraparesis (TSP). Because some TSP patients have biological false positive tests for treponemal infections (BFP-STS), we used ELISA to study BFP-STS and anticardiolipin antibodies in 42 Jamaican TSP patients. The data indicate that in TSP anticardiolipin antibodies occur in about 26% of patients, are associated with biological false positive treponemal serology, are relatively restricted to the IgA isotype and may be induced by HTLV-1 or other nontreponemal infections.

The effects of d-amphetamine, apomorphine and white noise on response switching in the rat were examined using a schedule of reinforcement which resulted in the subjects displaying a range of different probabilities of switching. The procedure was analogous to the use of a fixed interval schedule of reinforcement for examining the rate-dependent effects of drugs. d-Amphetamine (0.4-4.0 mg/kg) increased response switching in a manner dependent both upon the dose of drug and the baseline probability of switching. Apomorphine (0.01-0.3 mg/kg) increased switching in a manner which depended upon dose but which was independent of the baseline probability of switching. Neither drug increased response rate, although both drugs reduced response rate at the highest doses. In contrast, continuous white noise (85-105 dB) increased response rate without affecting switching. The results indicate that different activating stimuli may have qualitatively different effects on behaviour.