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Analysis of human blood immune cells provides insights into the coordinated response to viral infections such as severe acute respiratory syndrome coronavirus 2, which causes coronavirus disease 2019 (COVID-19). We performed single-cell transcriptome, surface proteome and T and B lymphocyte antigen receptor analyses of over 780,000 peripheral blood mononuclear cells from a cross-sectional cohort of 130 patients with varying severities of COVID-19. We identified expansion of nonclassical monocytes expressing complement transcripts ( CD16 + C1QA/B/C + ) that sequester platelets and were predicted to replenish the alveolar macrophage pool in COVID-19. Early, uncommitted CD34 + hematopoietic stem/progenitor cells were primed toward megakaryopoiesis, accompanied by expanded megakaryocyte-committed progenitors and increased platelet activation. Clonally expanded CD8 + T cells and an increased ratio of CD8 + effector T cells to effector memory T cells characterized severe disease, while circulating follicular helper T cells accompanied mild disease. We observed a relative loss of IgA2 in symptomatic disease despite an overall expansion of plasmablasts and plasma cells. Our study highlights the coordinated immune response that contributes to COVID-19 pathogenesis and reveals discrete cellular components that can be targeted for therapy. Transcriptomic and proteomic profiling of blood samples from individuals with COVID-19 reveals immune cell and hematopoietic progenitor cell alterations that are differentially associated with disease severity.

The relationship between the human placenta—the extraembryonic organ made by the fetus, and the decidua—the mucosal layer of the uterus, is essential to nurture and protect the fetus during pregnancy. Extravillous trophoblast cells (EVTs) derived from placental villi infiltrate the decidua, transforming the maternal arteries into high-conductance vessels 1 . Defects in trophoblast invasion and arterial transformation established during early pregnancy underlie common pregnancy disorders such as pre-eclampsia 2 . Here we have generated a spatially resolved multiomics single-cell atlas of the entire human maternal–fetal interface including the myometrium, which enables us to resolve the full trajectory of trophoblast differentiation. We have used this cellular map to infer the possible transcription factors mediating EVT invasion and show that they are preserved in in vitro models of EVT differentiation from primary trophoblast organoids 3 , 4 and trophoblast stem cells 5 . We define the transcriptomes of the final cell states of trophoblast invasion: placental bed giant cells (fused multinucleated EVTs) and endovascular EVTs (which form plugs inside the maternal arteries). We predict the cell–cell communication events contributing to trophoblast invasion and placental bed giant cell formation, and model the dual role of interstitial EVTs and endovascular EVTs in mediating arterial transformation during early pregnancy. Together, our data provide a comprehensive analysis of postimplantation trophoblast differentiation that can be used to inform the design of experimental models of the human placenta in early pregnancy. A multiomics single-cell atlas of the human maternal–fetal interface including the myometrium, combining spatial transcriptomics data with chromatin accessibility, provides a comprehensive analysis of cell states as placental cells infiltrate the uterus during early pregnancy.

Using a whole-watershed approach and a combination of historical, contemporary, modeled and paleolimnological datasets, we show that the High Arctic’s largest lake by volume (Lake Hazen) has succumbed to climate warming with only a ~1 °C relative increase in summer air temperatures. This warming deepened the soil active layer and triggered large mass losses from the watershed’s glaciers, resulting in a ~10 times increase in delivery of glacial meltwaters, sediment, organic carbon and legacy contaminants to Lake Hazen, a >70% decrease in lake water residence time, and near certainty of summer ice-free conditions. Concomitantly, the community assemblage of diatom primary producers in the lake shifted dramatically with declining ice cover, from shoreline benthic to open-water planktonic species, and the physiological condition of the only fish species in the lake, Arctic Char, declined significantly. Collectively, these changes place Lake Hazen in a biogeochemical, limnological and ecological regime unprecedented within the past ~300 years. Arctic ecosystems are at threat due to the rapid nature of climate change and Arctic amplification. Here, the authors show that the watershed of Lake Hazen, the Arctic’s largest lake by volume, has undergone dramatic changes in response to as little as a ~1°C increase in summer air temperatures.

This clinical trial compared mitral-valve repair with replacement for severe ischemic mitral regurgitation. There were no significant between-group differences in left ventricular remodeling and clinical outcomes, but replacement was associated with more durable correction. Functional ischemic mitral regurgitation affects 1.6 million to 2.8 million patients in the United States and is associated with a doubling in mortality among patients with mild or greater degrees of mitral regurgitation after myocardial infarction. 1 – 3 Ischemic mitral regurgitation is a consequence of adverse left ventricular remodeling after myocardial injury with enlargement of the left ventricular chamber and mitral annulus, apical and lateral migration of the papillary muscles, leaflet tethering, and reduced closing forces. These processes lead to malcoaptation of the leaflets and variable degrees of mitral regurgitation that can fluctuate dynamically as a function of volume status, afterload, . . .

The endometrium, the mucosal lining of the uterus, undergoes dynamic changes throughout the menstrual cycle in response to ovarian hormones. We have generated dense single-cell and spatial reference maps of the human uterus and three-dimensional endometrial organoid cultures. We dissect the signaling pathways that determine cell fate of the epithelial lineages in the lumenal and glandular microenvironments. Our benchmark of the endometrial organoids reveals the pathways and cell states regulating differentiation of the secretory and ciliated lineages both in vivo and in vitro. In vitro downregulation of WNT or NOTCH pathways increases the differentiation efficiency along the secretory and ciliated lineages, respectively. We utilize our cellular maps to deconvolute bulk data from endometrial cancers and endometriotic lesions, illuminating the cell types dominating in each of these disorders. These mechanistic insights provide a platform for future development of treatments for common conditions including endometriosis and endometrial carcinoma. Single-cell and spatial transcriptomic profiling of the human endometrium highlights pathways governing the proliferative and secretory phases of the menstrual cycle. Analyses of endometrial organoids show that WNT and NOTCH signaling modulate differentiation into the secretory and ciliated epithelial lineages, respectively.

Glacial runoff is predicted to increase in many parts of the Arctic with climate change, yet little is known about the biogeochemical impacts of meltwaters on downstream freshwater ecosystems. Here we document the contemporary limnology of the rapidly changing glacierized watershed of the world’s largest High Arctic lake (Lake Hazen), where warming since 2007 has increased delivery of glacial meltwaters to the lake by up to 10-times. Annually, glacial meltwaters accounted for 62–98% of dissolved nutrient inputs to the lake, depending on the chemical species and year. Lake Hazen was a strong sink for NO 3 − -NO 2 − , NH 4 + and DOC, but a source of DIC to its outflow the Ruggles River. Most nutrients entering Lake Hazen were, however, particle-bound and directly transported well below the photic zone via dense turbidity currents, thus reinforcing ultraoligotrophy in the lake rather than overcoming it. For the first time, we apply the land-to-ocean aquatic continuum framework in a large glacierized Arctic watershed, and provide a detailed and holistic description of the physical, chemical and biological limnology of the rapidly changing Lake Hazen watershed. Our findings highlight the sensitivity of freshwater ecosystems to the changing cryosphere, with implications for future water quality and productivity at high latitudes.

Glanders is a zoonotic contagious disease of equids caused by Burkholderia (B.) mallei. Serodiagnosis of the disease is challenging because of false-positive and false-negative test results. The accuracy of the complement fixation test (CFT) which is prescribed for international trade by the World Organisation for Animal Health (OIE), five ELISAs and a Western blot (WB) were compared for serodiagnosis of glanders using sera from 3,000 glanders-free and 254 glanderous equids. Four ELISA tests are based on recombinant antigens (TssA, TssB, BimA and Hcp1), the IDVet ELISA is based on a semi-purified fraction of B. mallei and WB makes use of a purified LPS-containing B. mallei-antigen. Sensitivity and specificity of tests were estimated using cut-off values recommended by the test developers. The WB and all ELISAs, except BimA, were significantly more specific than the CFT. ELISAs based on TssA, TssB, and BimA antigens had significantly lower sensitivity compared to CFT while the sensitivities of the Hcp1-ELISA, the IDVet-ELISA and the WB did not differ significantly from that of the CFT. Given their comparable sensitivities and specificities, the CFT (98.0%, 96.4%), the WB (96.8%, 99.4%), the Hcp1-ELISA (95.3%, 99.6%) and the IDVet-ELISA (92.5%, 99.5%) should be further developed to meet OIE requirements.

This trial compared coronary-artery bypass grafting alone with CABG plus mitral-valve repair in patients with coronary artery disease and moderate ischemic mitral regurgitation. Mitral-valve repair provided no apparent benefit and was associated with more neurologic complications. Each year, approximately 1 million Americans have a myocardial infarction, and nearly 8 million Americans have a history of myocardial infarction. 1 Ischemic mitral regurgitation, which results from functional-valve incompetence due to myocardial injury and adverse left ventricular remodeling, develops in approximately 50% of patients after an infarction, and moderate regurgitation occurs in more than 10% of patients. 2 – 4 Ischemic mitral regurgitation is associated with excess mortality regardless of management. 5 , 6 The valve leaflets and chordal structures in affected patients are “innocent bystanders”; mitral regurgitation results from papillary muscle displacement, leaflet tethering, reduced closing forces, and annular dilatation. 7 – 10 Many patients . . .

Frailty is known to be associated with poorer outcomes in individuals admitted to hospital for medical conditions requiring intensive care. However, little evidence is available for the effect of frailty on patients’ outcomes after traumatic brain injury. Many frailty indices have been validated for clinical practice and show good performance to predict clinical outcomes. However, each is specific to a particular clinical context. We aimed to develop a frailty index to predict 6-month outcomes in patients after a traumatic brain injury. A cumulative deficit approach was used to create a novel frailty index based on 30 items dealing with disease states, current medications, and laboratory values derived from data available from CENTER-TBI, a prospective, longitudinal observational study of patients with traumatic brain injury presenting within 24 h of injury and admitted to a ward or an intensive care unit at 65 centres in Europe between Dec 19, 2014, and Dec 17, 2017. From the individual cumulative CENTER-TBI frailty index (range 0–30), we obtained a standardised value (range 0–1), with high scores indicating higher levels of frailty. The effect of frailty on 6-month outcome evaluated with the extended Glasgow Outcome Scale (GOSE) was assessed through a proportional odds logistic model adjusted for known outcome predictors. An unfavourable outcome was defined as death or severe disability (GOSE score ≤4). External validation was performed on data from TRACK-TBI, a prospective observational study co-designed with CENTER-TBI, which enrolled patients with traumatic brain injury at 18 level I trauma centres in the USA from Feb 26, 2014, to July 27, 2018. CENTER-TBI is registered with ClinicalTrials.gov, NCT02210221; TRACK-TBI is registered at ClinicalTrials.gov, NCT02119182. 2993 participants (median age was 51 years [IQR 30–67], 2058 [69%] were men) were included in this analysis. The overall median CENTER-TBI frailty index score was 0·07 (IQR 0·03–0·15), with a median score of 0·17 (0·08–0·27) in older adults (aged ≥65 years). The CENTER-TBI frailty index score was significantly associated with the probability of an increasingly unfavourable outcome (cumulative odds ratio [OR] 1·03, 95% CI 1·02–1·04; p<0·0001), and the association was stronger for participants admitted to hospital wards (1·04, 1·03–1·06, p<0·0001) compared with those admitted to the intensive care unit (1·02, 1·01–1·03 p<0·0001). External validation of the CENTER-TBI frailty index in data from the TRACK-TBI (n=1667) cohort supported the robustness and reliability of these findings. The overall median TRACK-TBI frailty index score was 0·03 (IQR 0–0·10), with the frailty index score significantly associated with the risk of an increasingly unfavourable outcome in patients admitted to hospital wards (cumulative OR 1·05, 95% CI 1·03–1·08; p<0·0001), but not in those admitted to the intensive care unit (1·01, 0·99–1·03; p=0·43). We developed and externally validated a frailty index specific to traumatic brain injury. Risk of unfavourable outcome was significantly increased in participants with a higher CENTER-TBI frailty index score, regardless of age. Frailty identification could help to individualise rehabilitation approaches aimed at mitigating effects of frailty in patients with traumatic brain injury. European Union, Hannelore Kohl Stiftung, OneMind, Integra LifeSciences Corporation, NeuroTrauma Sciences, NIH-NINDS–TRACK-TBI, US Department of Defense.