1. The Department of Internal Medicine, Division of Diabetes, Endocrinology and Metabolism, University of Nebraska Medical Center, Omaha, NE 68198, USA
2. The VA Nebraska Western Iowa Health Care System, Omaha, NE 68105, USA
3. Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE 68198, USA
4. The Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588, USA
5. Nebraska Center for Integrated Biomolecular Communication, University of Nebraska-Lincoln, Lincoln, NE 68588, USA