Browsing by Author "Rogers, James A."

Now showing 1 - 3 of 3
  • Thumbnail Image
    ItemOpen Access
    Detecting Deoxyhemoglobin in Spinal Cord Vasculature of the Experimental Autoimmune Encephalomyelitis Mouse Model of Multiple Sclerosis Using Susceptibility MRI and Hyperoxygenation
    (PLOS ONE, 2015-05-18) Nathoo, Nabeela; Rogers, James A.; Yong, V. Wee; Dunn, Jeff F.
    Susceptibility-weighted imaging (SWI) detects hypointensities due to iron deposition and deoxyhemoglobin. Previously it was shown that SWI detects hypointensities in the experimental autoimmune encephalomyelitis (EAE) model of multiple sclerosis (MS), most of which are due to intravascular deoxyhemoglobin, with a small proportion being due to iron deposition in the central nervous system parenchyma and demyelination. However, animals had to be sacrificed to differentiate these two types of lesions which is impractical for time course studies or for human application. Here, we proposed altering the inspired oxygen concentration during imaging to identify deoxyhemoglobin-based hypointensities in vivo. SWI was performed on lumbar spinal cords of naive control and EAE mice using 30% O2 then 100% O2. Some mice were imaged using 30% O2, 100% O2 and after perfusion. Most SWI-visible hypointensities seen with 30% O2 changed in appearance upon administration of 100% O2, and were not visible after perfusion. That hypointensities changed with hyperoxygenation indicates that they were caused by deoxyhemoglobin. We show that increasing the inspired oxygen concentration identifies deoxyhemoglobin-based hypointensities in vivo. This could be applied in future studies to investigate the contribution of vascular-based hypointensities with SWI in EAE and MS over time.
  • No Thumbnail Available
    ItemOpen Access
    Gray matter hypoxia in the brain of the experimental autoimmune encephalomyelitis model of multiple sclerosis
    (2016-01-14) Johnson, Thomas W.; Dunn, Jeff F.; Wu, Ying; Nathoo, Nabeela; Rogers, James A.; Yong, V. Wee
    Background: Multiple sclerosis has a significant inflammatory component. As inflammation can induce and be modulated by hypoxia, the presence of hypoxia could provide clues about immune response regulation in MS. Objective: quantify oxygenation in gray matter (GM) of mice with the experimental autoimmune encephalomyelitis (EAE) model to determine if hypoxia exists in a demyelination model associated with chronic inflammation. Methods: C57BL/6 mice were implanted with a fiber-optic sensor in the cerebellum (n=13) and cortex (n=21). We measured PO2 in awake, unrestrained animals from baseline up to 36 days post-induction for EAE. Results: There were more days with hypoxia compared with hyperoxia (cerebellum: 13/67 vs. 7/67 days; cortex: 15/112 vs. 2/112). Cerebellum showed the largest differences between days 13-17, corresponding to high behavioral deficits. This occurred later for cortex (day 23). Hypoxia in the cortex correlated with increased behavioral deficits and increased variation (based on z-score comparisons with baseline and age-matched controls) in the cerebellum correlated with clinical deficits. Conclusions: The presence of hypoxia and increased variation in GM oxygenation indicates that oxygen may change enough to modulate the immune response. The cause may relate to increased metabolic dysfunction, disruption of neurovascular coupling or increased oxidative metabolism in activated microglia.
  • No Thumbnail Available
    ItemOpen Access