Re-evaluating Water Column Reoxygenation during the End Permian Mass Extinction

Ocean anoxia is considered a key driver of the end-Permian mass extinction (EPME). However, it is much debated whether there was an ocean reoxygenation phase during, and in the aftermath, of the EPME. Evidence for ocean reoxygenation is often inferred from the absence of framboidal pyrite in some boundary marine sediments (termed the "framboid gap"). To reconstruct ocean redox evolution across the EPME we investigate the carbon isotopic, sedimentological, and redox records of the Ruichang and Ehtan sections in South China. These document two negative δ13Ccarb excursions and the development of anoxia associated with deepening leading up to the Permian-Triassic boundary. Above the level at which most siliceous organisms became extinct, pyrite framboid and iron proxies indicate that water column redox conditions were predominantly oxygenated but sporadically anoxic/ferruginous [non-sulfidic, free Fe(Ⅱ) in the water] at Ruichang, while ferruginous conditions were more widely developed at Ehtan. These contrasting redox states are characteristic of a dynamic ocean redox landscape in the extinction interval. The “framboid gap” is seen in strata deposited under both oxic and ferruginous conditions, suggesting the availability of decomposable organic matter for sulfate reduction additionally controlled framboid genesis. Our data confirm that oxygenated conditions were developed in some deep water basins during the EPME

Endovascular therapy in acute ischaemic stroke with large infarction with matched or mismatched clinical-radiological severities: a post-hoc analysis of the ANGEL-ASPECT trialResearch in context

Summary: Background: Endovascular therapy (EVT) was demonstrated effective in acute large vessel occlusion (LVO) with large infarction. Revealing subgroups of patients who would or would not benefit from EVT will further inform patient selection for EVT. Methods: This post-hoc analysis of the ANGEL-ASPECT trial, a randomised controlled trial of 456 adult patients with acute anterior-circulation LVO and large infarction, defined by ASPECTS 3–5 or infarct core volume 70–100 mL, enrolled from 46 centres across China, between October 2, 2020 and May 18, 2022. Patients were randomly assigned (1:1) to receiving EVT and medical management or medical management alone. One patient withdrew consent, 455 patients were included in this post-hoc analysis and categorised into 4 subgroups by lower or higher NIHSS (< or ≥16) and smaller or larger infarct core (< or ≥70 mL). Those with lower NIHSS &amp; smaller core, and higher NIHSS &amp; larger core were considered clinical-radiological matched subgroups; otherwise clinical-radiological mismatched subgroups. Primary outcome was 90-day modified Rankin Scale (mRS). ANGEL-ASPECT is registered with ClinicalTrials.gov, NCT04551664. Findings: Overall, 139 (30.5%) patients had lower NIHSS &amp; smaller core, 106 (23.3%) higher NIHSS &amp; larger core, 130 (28.6%) higher NIHSS &amp; smaller core, and 80 (17.6%) lower NIHSS &amp; larger core. There was significant ordinal shift in the 90-day mRS toward a better outcome with EVT in clinical-radiological matched subgroups: lower NIHSS &amp; smaller core (generalised OR, 1.76; 95% CI, 1.18–2.62; p = 0.01) and higher NIHSS &amp; larger core (1.64; 1.06–2.54; 0.01); but not in the two clinical-radiological mismatched subgroups. Interpretation: Our findings suggested that in patients with anterior-circulation LVO and large infarction, EVT was associated with improved 90-day functional outcomes in those with matched clinical and radiological severities, but not in those with mismatched clinical and radiological severities. Simultaneous consideration of stroke severity and infarct core volume may inform patient selection for EVT. Funding: Unrestricted grants from industry [Covidien Healthcare International Trading (Shanghai), Johnson &amp; Johnson MedTech, Genesis MedTech (Shanghai), and Shanghai HeartCare Medical Technology]