1. Ferguson Laboratory for Spine Research, Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, PA 15261, USA
2. Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
3. Department of Health Information Management, University of Pittsburgh, Pittsburgh, PA 15260, USA
4. Institute of the Biology of Aging and Metabolism and Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA