[1] GlaxoSmithKline, Res Triangle Pk, NC 27709 USA
[2] Natl Inst Pain, COPE Fdn, Tampa, FL USA
[3] Univ Calif San Francisco, Dept Physiol Nursing, San Francisco, CA 94143 USA
[4] Consumer Hlth Sci, Princeton, NJ USA
[5] GlaxoSmithKline, Greenford, Middx, England