Search

Here we report on a two year continuous survey to examine possible VLF signals associated with meteors brighter than magnitude -5. Our survey allowed both calibrated temporal and spatial correlations between VLF signals and fireball lightcurves. We used continuous observations from the Atmospheric Weather Electromagnetic System for Observation Modeling and Education (AWESOME) VLF receiver system (Cohen et al., 2010) deployed at the Elginfield Observatory near London, Ontario, Canada (43N, 81W) to monitor VLF radio signals and correlate with all-sky video recordings of fireballs. This survey from May 2017 to March 2019 was cued using fireballs detected by the Southern Ontario Meteor Network (Brown et al., 2010; Weryk et al., 2007). The GPS conditioned timing of the AWESOME system was continuously synchronized with video recordings directly in the video stream to ensure sub-frame VLF-optical time calibration. The AWESOME system has two orthogonal VLF antennas which permits directional calculation of incoming VLF signals, which were compared to the apparent optically measured locations of simultaneously detected fireballs. VLF events potentially linked to fireballs were checked against the National Lightning Detection Network (NLDN) database to remove false positive association with lightning. During the two year survey interval, over 80 bright meteors (apparent magnitude brighter than -5, brightest recorded event -7.8) were detected and compared to VLF signals detected by the AWESOME system. No definitive evidence was found for VLF emission from meteors up to a limiting magnitude of -7.8., Comment: 51 pages; accepted for publication in Planetary and Space Science

Background & Aims Perpetuate liver inflammation is crucial in the pathogenesis of non-alcoholic steatohepatitis (NASH). Expression of CXCL10, a pro-inflammatory cytokine, correlates positively with obesity and type 2 diabetes. Whether CXCL10 plays a role in NASH was unknown. We aimed to investigate the functional and clinical impact of CXCL10 in NASH. Methods Cxcl10 gene-deleted ( Cxcl10 −/− ) and C57BL/6 wild type (WT) mice were fed a methionine- and choline-deficient (MCD) diet for 4 or 8weeks. In other experiments, we injected neutralizing anti-CXCL10 mAb into MCD-fed WT mice. Human serum was obtained from 147 patients with biopsy-proven non-alcoholic fatty liver disease and 73 control subjects. Results WT mice, fed the MCD diet, developed steatohepatitis with higher hepatic CXCL10 expression. Cxcl10 −/− mice were refractory to MCD-induced steatohepatitis. We further revealed that CXCL10 was associated with the induction of important pro-inflammatory cytokines (TNF-α, IL-1β, and MCP-1) and activation of the NF-κB pathway. CXCL10 was linked to steatosis through upregulation of the lipogenic factors SREBP-1c and LXR, and also to oxidative stress (upregulation of CYP2E1 and C/EBPβ). Blockade of CXCL10 protected against hepatocyte injury in vitro and against steatohepatitis development in mice. We further investigated the clinical impact of CXCL10 and found circulating and hepatic CXCL10 levels were significantly higher in human NASH. Importantly, the circulating CXCL10 level was correlated with the degree of lobular inflammation and was an independent risk factor for NASH patients. Conclusions We demonstrate for the first time that CXCL10 plays a pivotal role in the pathogenesis of experimental steatohepatitis. CXCL10 maybe a potential non-invasive biomarker for NASH patients.