[1] Childrens Hosp, Div Gastroenterol, Boston, MA 02115 USA
[2] Diana Princess Wales Hosp, Birmingham, W Midlands, England
[3] John Paul II Hosp, Krakow, Poland
[4] Hosp Ninos Dr Ricardo Gutierrez, Buenos Aires, DF, Argentina
[5] Hosp Geral de Santo Antonio, Oporto, Portugal
[6] Johns Hopkins Univ, Baltimore, MD USA
[7] GlaxoSmithKline, Res Triangle Pk, NC USA
[8] GlaxoSmithKline, Greenford, Middx, England
[9] Clin Univ St Luc, B-1200 Brussels, Belgium