Lipid analysis of CO2-rich subsurface aquifers suggests an autotrophy-based deep biosphere with lysolipids enriched in CPR bacteria.

Sediment-hosted CO2-rich aquifers deep below the Colorado Plateau (USA) contain a remarkable diversity of uncultivated microorganisms, including Candidate Phyla Radiation (CPR) bacteria that are putative symbionts unable to synthesize membrane lipids. The origin of organic carbon in these ecosystems is unknown and the source of CPR membrane lipids remains elusive. We collected cells from deep groundwater brought to the surface by eruptions of Crystal Geyser, sequenced the community, and analyzed the whole community lipidome over time. Characteristic stable carbon isotopic compositions of microbial lipids suggest that bacterial and archaeal CO2 fixation ongoing in the deep subsurface provides organic carbon for the complex communities that reside there. Coupled lipidomic-metagenomic analysis indicates that CPR bacteria lack complete lipid biosynthesis pathways but still possess regular lipid membranes. These lipids may therefore originate from other community members, which also adapt to high in situ pressure by increasing fatty acid unsaturation. An unusually high abundance of lysolipids attributed to CPR bacteria may represent an adaptation to membrane curvature stress induced by their small cell sizes. Our findings provide new insights into the carbon cycle in the deep subsurface and suggest the redistribution of lipids into putative symbionts within this community

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Design of the stenting and aggressive medical management for preventing recurrent stroke in intracranial stenosis trial.

BACKGROUND: Patients with recent transient ischemic attack (TIA) or stroke caused by 70% to 99% stenosis of a major intracranial artery are at high risk of recurrent stroke on usual medical management, suggesting the need for alternative therapies for this disease. METHODS: The Stenting and Aggressive Medical Management for Preventing Recurrent stroke in Intracranial Stenosis trial is an ongoing, randomized, multicenter, 2-arm trial that will determine whether intracranial angioplasty and stenting adds benefit to aggressive medical management alone for preventing the primary endpoint (any stroke or death within 30 days after enrollment or after any revascularization procedure of the qualifying lesion during follow-up, or stroke in the territory of the symptomatic intracranial artery beyond 30 days) during a mean follow-up of 2 years in patients with recent TIA or stroke caused by 70% to 99% stenosis of a major intracranial artery. Aggressive medical management in both arms consists of aspirin 325 mg per day, clopidogrel 75 mg per day for 90 days after enrollment, intensive risk factor management primarily targeting systolic blood pressure(diabetics) and low density cholesterol/dL, and a lifestyle modification program. The sample size required to detect a 35% reduction in the rate of the primary endpoint from angioplasty and stenting based on the log-rank test with an alpha of 0.05, 80% power, and adjusting for a 2% loss to follow-up and 5% crossover from the medical to the stenting arm is 382 patients per group. RESULTS: Enrollment began in November 2008 and 451 patients have been enrolled as of March 31, 2011. CONCLUSIONS: This is the first randomized stroke prevention trial to compare angioplasty and stenting with medical therapy in patients with intracranial arterial stenosis and to incorporate intensive management of multiple risk factors and a lifestyle modification program in the study design. Hopefully, the results of the trial will lead to more effective therapy for this high-risk disease

Factors Associated With Recurrent Ischemic Stroke in the Medical Group of the SAMMPRIS Trial

IMPORTANCE: The Stenting and Aggressive Medical Management for Preventing Recurrent Stroke in Intracranial Stenosis (SAMMPRIS) Trial showed that aggressive medical therapy was more effective than stenting for preventing stroke in patients with symptomatic intracranial stenosis. However, 15% of patients in the medical group still experienced a primary end point during a median follow-up of 32.7 months. OBJECTIVE: To determine baseline features that were associated with a high rate of a primary end point in the medical arm of the SAMMPRIS Trial. DESIGN, SETTING, AND PARTICIPANTS: A post hoc analysis of patients in the medical arm only of the SAMMPRIS trial. Enrollment occurred between October 2008 and April 2013 and included 227 patients randomized to medical management alone. Baseline demographic features, vascular risk factors, qualifying event, brain imaging, and angiographic features were analyzed. Bivariate and multivariable proportional hazard regression modeling was performed to relate baseline features to the time until a primary end point. The post hoc analysis was conducted from November 2014 to June 2015. INTERVENTIONS: The SAMMPRIS Trial compared stenting with aggressive medical management in patients with a stroke or transient ischemic attack attributed to 70% to 99% stenosis of a major intracranial artery. MAIN OUTCOMES AND MEASURES: The primary outcome was any of the following: stroke or death within 30 days of enrollment, ischemic stroke in the territory of the symptomatic intracranial artery beyond 30 days after enrollment, or any stroke or death within 30 days after stenting a patient in the medical group during follow-up. RESULTS: A total of 227 patients were included in the study, 82 of whom were female, and the mean (SD) age was 59.5 (11.8) years. Being female (hazard ratio [HR], 1.9; 95% CI, 0.96-3.7), having diabetes mellitus (HR, 1.8; 95% CI, 0.9-3.5), not taking a statin at enrollment (HR, 2.6; 95% CI, 1.2-5.7), stroke as the qualifying event (HR, 2.5; 95% CI, 1.03-6.0), Rankin grade of 1 or greater (HR, 2.3; 95% CI, 0.9-5.5), old infarct in the territory of the stenotic artery (HR, 2.6; 95% CI, 1.3-5.1), and greater than 80% stenosis (HR, 1.9; 95% CI, 0.9-3.7) were associated (P \u3c .10) with higher risk on bivariate analysis. Factors that were significantly associated with a primary end point on multivariable analyses were old infarct in the territory (HR, 2.6; 95% CI, 1.3-5.3; P = .006), stroke as the qualifying event (HR, 3.0; 95% CI, 1.1-7.7; P = .03), and no statin use at enrollment (HR, 2.4; 95% CI, 1.1-5.2; P = .03). CONCLUSIONS AND RELEVANCE: Old infarct in the territory of the stenosis, new stroke presentation, and absence of statin use at enrollment were independently associated with high rates of the primary end point in the medical group in the SAMMPRIS Trial. These features may be useful for selecting high-risk patients for future clinical trials evaluating alternative therapies for intracranial stenosis. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00576693

Lipid analysis of CO2-rich subsurface aquifers suggests an autotrophy-based deep biosphere with lysolipids enriched in CPR bacteria.

Sediment-hosted CO2-rich aquifers deep below the Colorado Plateau (USA) contain a remarkable diversity of uncultivated microorganisms, including Candidate Phyla Radiation (CPR) bacteria that are putative symbionts unable to synthesize membrane lipids. The origin of organic carbon in these ecosystems is unknown and the source of CPR membrane lipids remains elusive. We collected cells from deep groundwater brought to the surface by eruptions of Crystal Geyser, sequenced the community, and analyzed the whole community lipidome over time. Characteristic stable carbon isotopic compositions of microbial lipids suggest that bacterial and archaeal CO2 fixation ongoing in the deep subsurface provides organic carbon for the complex communities that reside there. Coupled lipidomic-metagenomic analysis indicates that CPR bacteria lack complete lipid biosynthesis pathways but still possess regular lipid membranes. These lipids may therefore originate from other community members, which also adapt to high in situ pressure by increasing fatty acid unsaturation. An unusually high abundance of lysolipids attributed to CPR bacteria may represent an adaptation to membrane curvature stress induced by their small cell sizes. Our findings provide new insights into the carbon cycle in the deep subsurface and suggest the redistribution of lipids into putative symbionts within this community