Molecular phenotyping of oxidative stress in diabetes mellitus with point-of-care NMR system

摘要

a The developed bench-top sized micro MR system consists of a commercial console, detection circuit coil mounted on a micro stage, and a palm-sized 0.5 T permanent magnet. The microcapillary tube which contains a single drop of blood is slotted into the radio-frequency probe for micro MR analysis. The read-out completes in <5 min. b The rf pulse sequences used were standard CPMG pulse sequence and standard inversion-recovery experiment (with CPMG detection) for the T2 relaxations, and T1 relaxations measurements, respectively. In order to obtain high signal-to-noise ratio under a relatively inhomogeneous magnetic environment, an array of echoes (a few thousands) within a very short echo interval (in the order of μs) were used to acquire spin-echoes from <4 μL sample volume of packed RBCs or plasma. c Redox reaction of the iron-heme in various oxidation states: Fe2+, Fe3+, Fe4+, and globin-radical Fe4+, which were chemically induced in in vitro environment (Methods Online). The hemoglobins were in two possible magnetic states: diamagnetic (red) and paramagnetic state (blue). d Various redox states of hemoglobin mapped out using the proposed T1–T2 magnetic state diagram. The coordinates (in ms) were oxy-Hb (T2 = 152 ± 10, T1 = 628 ± 25), deoxy-Hb (T2 = 124 ± 12, T1 = 622 ± 15), met-Hb (T2 = 102 ± 2, T1 = 198 ± 5), ferryl Hb (T2 = 139 ± 10, T1 = 522 ± 20), oxo ferryl-Hb (T2 = 34.2 ± 4, T1 = 95.2 ± 6), nitrosyl-Hb (T2 = 121 ± 4, T1 = 204 ± 8), and hemichrome (T2 = 108 ± 4, T1 = 603 ± 11). Three different samplings were taken from the same donor, and the results were reported as mean ± standard error measurement. The data is represented by box-plot format. e A quadrant chart of diabetic subject stratified into subgroups based on their oxidative status (e.g., antioxidant capacity (left) and oxidative stress (right), in which the oxidative stress here includes nitrosative stress and peroxidative stress), in association with their glycemic index (e.g., HbA1c). f Relationship between elevation of oxidative stress and development of DM-related complications (e.g., cardiovascular event).