Oxidative Stress Monitoring Platform: A Longitudinal In vitro Multinuclear (1H/19F) MR Spectroscopic Study.

Abstract

Glutathione (GSH) is a master antioxidant that counters oxidative stress. Clinical studies have confirmed significant depletion of GSH in the hippocampus and the substantia nigra as an early diagnostic biomarker for Alzheimer's disease (AD) and Parkinson disease (PD), respectively. External agents like anesthetics (inhaled and intravenous) have a different impact on GSH. There is significant depletion of the serum GSH peroxidase level after surgery with isoflurane anesthesia that is not found in patients administered intravenous propofol. The objective of this study is to evaluate the GSH level associated with isoflurane in vitro phantom model using non-invasive magnetic resonance (MR) spectroscopy and to detect residual isoflurane in a solution. MRS data was generated utilizing a 3T MR scanner (Prisma, Siemens) equipped with a 64-channel ¹H head coil and dual tune (¹⁹F/¹H) head coil. The GSH data acquisition was performed using the MEGA-PRESS pulse sequence using experimental parameters: ON = 4.40 ppm, OFF = 5.00 ppm, TE = 120 ms, TR = 2500 ms, voxel size = 25 × 25 × 25 mm and average = 32. Isoflurane was detected using ¹⁹F MRS studies using ¹⁹F/¹H head coil. GSH data was processed using KALPANA package and ¹⁹F data was processed using Siemens package. The GSH peak area (without isoflurane) in a phosphate-buffered solution (PBS) solution (control) showed a slow decline over time due to natural oxidation of GSH to dimeric glutathione (GSSG). On the contrary, the GSH peak area in similar model is reduced significantly (p = 0.016) due to isoflurane induced oxidation of GSH to GSSG compared to control. We also report a concise general method for data generation and processing of ¹H MRS data for GSH as well as ¹⁹F monitoring platform using ¹⁹F MR spectroscopy. This is the first report wherein both ¹H and ¹⁹F spectroscopy are applied to generate MRS data along with a unique data processing method. This method is highly sensitive and specifically detects GSH without ambiguity as well as isoflurane due to the unique chemical shift patterns of CF₃ and CHF₂ moieties. This non-invasive MRS approach is developed to monitor GSH-isoflurane interaction leading to oxidative stress and this approach can be extended for other inhaled anesthetics. This methodology using non-invasive ¹⁹F MR spectroscopy needs further development for future clinical studies.