Adipocyte Turnover: Relevance to Human Adipose Tissue Morphology

International audienceOBJECTIVE: Adipose tissue may contain few large adipocytes (hypertrophy) or many small adipocytes (hyperplasia). We investigated factors of putative importance for adipose tissue morphology. RESEARCH DESIGN AND METHODS: Subcutaneous adipocyte size and total fat mass were compared in 764 subjects with BMI 18-60 kg/m(2). A morphology value was defined as the difference between the measured adipocyte volume and the expected volume given by a curved-line fit for a given body fat mass and was related to insulin values. In 35 subjects, in vivo adipocyte turnover was measured by exploiting incorporation of atmospheric (14)C into DNA. RESULTS: Occurrence of hyperplasia (negative morphology value) or hypertrophy (positive morphology value) was independent of sex and body weight but correlated with fasting plasma insulin levels and insulin sensitivity, independent of adipocyte volume (beta-coefficient = 0.3, P < 0.0001). Total adipocyte number and morphology were negatively related (r = -0.66); i.e., the total adipocyte number was greatest in pronounced hyperplasia and smallest in pronounced hypertrophy. The absolute number of new adipocytes generated each year was 70% lower (P < 0.001) in hypertrophy than in hyperplasia, and individual values for adipocyte generation and morphology were strongly related (r = 0.7, P < 0.001). The relative death rate (approximately 10% per year) or mean age of adipocytes (approximately 10 years) was not correlated with morphology. CONCLUSIONS: Adipose tissue morphology correlates with insulin measures and is linked to the total adipocyte number independently of sex and body fat level. Low generation rates of adipocytes associate with adipose tissue hypertrophy, whereas high generation rates associate with adipose hyperplasia

Figuring Out Gas &amp; Galaxies In Enzo (FOGGIE). IV. The Stochasticity of Ram Pressure Stripping in Galactic Halos

We study ram pressure stripping in simulated Milky Way-like halos at z>=2 from the Figuring Out Gas & Galaxies In Enzo (FOGGIE) project. These simulations reach exquisite resolution in their circumgalactic medium (CGM) gas owing to FOGGIE's novel refinement scheme. The CGM of each halo spans a wide dynamic range in density and velocity over its volume---roughly 6 dex and 1000 km/s, respectively---translating into a 5 dex range in ram pressure imparted to interacting satellites. The ram pressure profiles of the simulated CGM are highly stochastic, owing to kpc-scale variations of the density and velocity fields of the CGM gas. As a result, the efficacy of ram pressure stripping depends strongly on the specific path a satellite takes through the CGM. The ram-pressure history of a single satellite is generally unpredictable and not well correlated with its approach vector with respect to the host galaxy. The cumulative impact of ram pressure on the simulated satellites is dominated by only a few short strong impulses---on average, 90% of the total surface momentum gained through ram pressure is imparted in 20% or less of the total orbital time. These results reveal an erratic mode of ram pressure stripping in Milky-Way like halos at high redshift---one that is not captured by a smooth spherically-averaged model of the circumgalactic medium.Comment: 18 pages, 10 figures. Submitted to Ap

Towards a dynamic checklist of lichen-forming, lichenicolous and allied fungi of Ecuador – using the <i>Consortium of Lichen Herbaria</i> to manage fungal biodiversity in a megadiverse country

peer reviewedA checklist of Lichen-forming, Lichenicolous and Allied Fungi of Ecuador is presented with a total of 2599 species, of which 39 are reported for the first time from the country. The names of three species, Hypotrachyna montufariensis, H. subpartita and Sticta hypoglabra, previously not validly published, are validated. Pertusaria oahuensis, originally introduced by Magnusson as ‘ad interim’, is validated as Lepra oahuensis. The form Leucodermia leucomelos f. albociliata is validated. Two new combinations, Fissurina tectigera and F. timida, are made, and Physcia mobergii is introduced as a replacement name for the illegitimate P. lobulata Moberg non (Flörke) Arnold. In an initial step, the checklist was compiled by reviewing literature records of Ecuadorian lichen biota spanning from the late 19th century to the present day. Subsequently, records were added based on vouchers from 56 collections participating in the Consortium of Lichen Herbaria, a Symbiota-based biodiversity platform with particular focus on, but not exclusive to, North and South America. Symbiota provides sophisticated tools to manage biodiversity data, such as occurrence records, a taxonomic thesaurus, and checklists. The thesaurus keeps track of frequently changing names, distinguishing taxa currently accepted from ones considered synonyms. The software also provides tools to create and manage checklists, with an emphasis on selecting vouchers based on occurrence records that can be verified for identification accuracy. Advantages and limitations of creating checklists in Symbiota versus traditional ways of compiling these lists are discussed. Traditional checklists are well suited to document current knowledge as a ‘snapshot in time’. They are important baselines, frequently used by ecologists and conservation scientists as an established naming convention for citing species reported from a country. Compiling these lists, however, requires an immense effort, only to inadequately address the dynamic nature of scientific discovery. Traditional checklists are thus quickly out of date, particularly in groups with rapidly changing taxonomy, such as lichenized fungi. Especially in megadiverse countries, where new species and new occurrences continue to be discovered, traditional checklists are not easily updated; these lists necessarily fall short of efficiently managing immense data sets, and they rely primarily on secondary evidence (i.e. literature records rather than specimens). Ideally, best practices make use of dynamic database platforms such as Symbiota to assess occurrence records based both on literature citations and voucher specimens. Using modern data management tools comes with a learning curve. Systems like Symbiota are not necessarily intuitive and their functionality can still be improved, especially when handling literature records. However, online biodiversity data platforms have much potential in more efficiently managing and assessing large biodiversity data sets, particularly when investigating the lichen biota of megadiverse countries such as Ecuador

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

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