[1] Acad Sci Czech Republic, Inst Physiol, CR-14220 Prague 4, Czech Republic
[2] Max Delbruck Ctr Mol Med, D-13125 Berlin, Germany
[3] Univ London Imperial Coll Sci & Technol, Fac Med, Ctr Clin Sci, MRC, London W12 0NN, England
[4] Ctr Appl Gen, Prague 14220 4, Czech Republic
[5] Charles Univ Prague, Inst Biol & Med Genet, Prague 12000 2, Czech Republic
[6] Univ Calif San Francisco, San Francisco, CA 94143 USA
[7] Univ London Imperial Coll Sci & Technol, Dept Epidemiol & Publ Hlth, London W2 1PG, England