[1] Univ Kiel, Clin Nephrol & Hypertens, D-24105 Kiel, Germany
[2] Columbia Univ, Dept Biol Sci, Dept Chem, New York, NY 10027 USA
[3] Columbia Univ, Howard Hughes Med Inst, New York, NY 10027 USA
[4] Klinikum LMU, Med Klin & Poliklin 4, D-80336 Munich, Germany