1. University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA, USA; Suite 502 Liliane Kaufmann Building, 3471 Fifth Avenue, Pittsburgh, PA 15213, USA Tel: (+ 1) 412 692 4343; fax: (+1) 412 692 4350;
2. University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA, USA
3. University of Pittsburgh School of Medicine, Pittsburgh, PA, USA