58 research outputs found
The detection of solid phosphorus and fluorine in the dust from the coma of comet 67P/Churyumov-Gerasimenko
Here, we report the detection of phosphorus and fluorine in solid
particles collected from the inner coma of comet
67P/Churyumov-Gerasimenko measured with the COmetary Secondary Ion Mass
Analyser (COSIMA) instrument on-board the Rosetta spacecraft, only a few
kilometers away from the comet nucleus. We have detected
phosphorus-containing minerals from the presented COSIMA mass spectra,
and can rule out e.g. apatite minerals as the source of phosphorus. This
result completes the detection of life-necessary CHNOPS-elements in
solid cometary matter, indicating cometary delivery as a potential
source of these elements to the young Earth. Fluorine was also detected
with CF+ secondary ions originating from the cometary dust. </p
Carbon-rich dust in comet 67P/Churyumov-Gerasimenko measured by COSIMA/Rosetta
Cometary ices are rich in CO2, CO and organic volatile
compounds, but the carbon content of cometary dust was only measured for
the Oort Cloud comet 1P/Halley, during its flyby in 1986. The COmetary
Secondary Ion Mass Analyzer (COSIMA)/Rosetta mass spectrometer
analysed dust particles with sizes ranging from 50 to 1000Â ÎŒm, collected
over 2 yr, from 67P/Churyumov-Gerasimenko (67P), a Jupiter family
comet. Here, we report 67P dust composition focusing on the elements C
and O. It has a high carbon content (atomic | |â )
close to the solar value and comparable to the 1P/Halley data. From
COSIMA measurements, we conclude that 67P particles are made of nearly
50 per cent organic matter in mass, mixed with mineral phases that are
mostly anhydrous. The whole composition, rich in carbon and non-hydrated
minerals, points to a primitive matter that likely preserved its
initial characteristics since the comet accretion in the outer regions
of the protoplanetary disc.</p
Nitrogen-to-carbon atomic ratio measured by COSIMA in the particles of comet 67P/ChuryumovâGerasimenko
The COmetary Secondary Ion Mass Analyzer (COSIMA) on board the Rosetta mission has analysed numerous cometary dust particles collected at very low velocities (a few m sâ1)
in the environment of comet 67P/ChuryumovâGerasimenko (hereafter 67P).
In these particles, carbon and nitrogen are expected mainly to be part
of the organic matter. We have measured the nitrogen-to-carbon (N/C)
atomic ratio of 27 cometary particles. It ranges from 0.018 to 0.06 with
an averaged value of 0.035 ± 0.011. This is compatible with the
measurements of the particles of comet 1P/Halley and is in the lower
range of the values measured in comet 81P/Wild 2 particles brought back
to Earth by the Stardust mission. Moreover, the averaged value
found in 67P particles is also similar to the one found in the insoluble
organic matter extracted from CM, CI and CR carbonaceous chondrites and
to the bulk values measured in most interplanetary dust particles and
micrometeorites. The close agreement of the N/C atomic ratio in all
these objects indicates that their organic matters share some
similarities and could have a similar chemical origin. Furthermore,
compared to the abundances of all the detected elements in the particles
of 67P and to the elemental solar abundances, the nitrogen is depleted
in the particles and the nucleus of 67P as was previously inferred also
for comet 1P/Halley. This nitrogen depletion could constrain the
formation scenarios of cometary nuclei.</p
Evidence of a causal and modifiable relationship between kidney function and circulating trimethylamine N-oxide
The host-microbiota co-metabolite trimethylamine N-oxide (TMAO) is linked to increased cardiovascular risk but how its circulating levels are regulated remains unclear. We applied "explainable" machine learning, univariate, multivariate and mediation analyses of fasting plasma TMAO concentration and a multitude of phenotypes in 1,741 adult Europeans of the MetaCardis study. Here we show that next to age, kidney function is the primary variable predicting circulating TMAO, with microbiota composition and diet playing minor, albeit significant, roles. Mediation analysis suggests a causal relationship between TMAO and kidney function that we corroborate in preclinical models where TMAO exposure increases kidney scarring. Consistent with our findings, patients receiving glucose-lowering drugs with reno-protective properties have significantly lower circulating TMAO when compared to propensity-score matched control individuals. Our analyses uncover a bidirectional relationship between kidney function and TMAO that can potentially be modified by reno-protective anti-diabetic drugs and suggest a clinically actionable intervention for decreasing TMAO-associated excess cardiovascular risk
Imidazole propionate is increased in diabetes and associated with dietary patterns and altered microbial ecology
Microbiota-host-diet interactions contribute to the development of metabolic diseases. Imidazole propionate is a novel microbially produced metabolite from histidine, which impairs glucose metabolism. Here, we show that subjects with prediabetes and diabetes in the MetaCardis cohort from three European countries have elevated serum imidazole propionate levels. Furthermore, imidazole propionate levels were increased in subjects with low bacterial gene richness and Bacteroides 2 enterotype, which have previously been associated with obesity. The Bacteroides 2 enterotype was also associated with increased abundance of the genes involved in imidazole propionate biosynthesis from dietary histidine. Since patients and controls did not differ in their histidine dietary intake, the elevated levels of imidazole propionate in type 2 diabetes likely reflects altered microbial metabolism of histidine, rather than histidine intake per se. Thus the microbiota may contribute to type 2 diabetes by generating imidazole propionate that can modulate host inflammation and metabolism
Low incidence of SARS-CoV-2, risk factors of mortality and the course of illness in the French national cohort of dialysis patients
Omecamtiv mecarbil in chronic heart failure with reduced ejection fraction, GALACTICâHF: baseline characteristics and comparison with contemporary clinical trials
Aims:
The safety and efficacy of the novel selective cardiac myosin activator, omecamtiv mecarbil, in patients with heart failure with reduced ejection fraction (HFrEF) is tested in the Global Approach to Lowering Adverse Cardiac outcomes Through Improving Contractility in Heart Failure (GALACTICâHF) trial. Here we describe the baseline characteristics of participants in GALACTICâHF and how these compare with other contemporary trials.
Methods and Results:
Adults with established HFrEF, New York Heart Association functional class (NYHA)ââ„âII, EF â€35%, elevated natriuretic peptides and either current hospitalization for HF or history of hospitalization/ emergency department visit for HF within a year were randomized to either placebo or omecamtiv mecarbil (pharmacokineticâguided dosing: 25, 37.5 or 50âmg bid). 8256 patients [male (79%), nonâwhite (22%), mean age 65âyears] were enrolled with a mean EF 27%, ischemic etiology in 54%, NYHA II 53% and III/IV 47%, and median NTâproBNP 1971âpg/mL. HF therapies at baseline were among the most effectively employed in contemporary HF trials. GALACTICâHF randomized patients representative of recent HF registries and trials with substantial numbers of patients also having characteristics understudied in previous trials including more from North America (n = 1386), enrolled as inpatients (n = 2084), systolic blood pressureâ<â100âmmHg (n = 1127), estimated glomerular filtration rate <â30âmL/min/1.73 m2 (n = 528), and treated with sacubitrilâvalsartan at baseline (n = 1594).
Conclusions:
GALACTICâHF enrolled a wellâtreated, highârisk population from both inpatient and outpatient settings, which will provide a definitive evaluation of the efficacy and safety of this novel therapy, as well as informing its potential future implementation
COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study
Background:
The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms.
Methods:
International, prospective observational study of 60â109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms.
Results:
âTypicalâ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (â€â18 years: 69, 48, 23; 85%), older adults (â„â70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each Pâ<â0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country.
Interpretation:
This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men
Animal Models of Human Cerebellar Ataxias: a Cornerstone for the Therapies of the Twenty-First Century
Characterization of the organic matter in the comet 67P/Churyumov-Gerasimenko
Les comĂštes comptent parmi les corps du SystĂšme Solaire les plus riches en matiĂšre organique. Les observations par tĂ©lĂ©dĂ©tection ont dĂ©jĂ permis dâidentifier plus dâune vingtaine de molĂ©cules organiques simples en phase gazeuse. Dâautre part, les missions dâexploration in situ (Giotto, VĂ©ga-1 et VĂ©ga-2) et la mission avec retour dâĂ©chantillon Stardust, ont Ă©tabli quâen plus de ces molĂ©cules volatiles relativement simples, une fraction notable de la matiĂšre carbonĂ©e comĂ©taire est prĂ©sente sous forme dâun matĂ©riau rĂ©fractaire restant en phase solide dans les grains comĂ©taires. COSIMA (Cometary Secondary Ion Mass Analyzer) est un spectromĂštre de masse dâions secondaires Ă temps de vol se trouvant Ă bord de lâorbiteur de la mission Rosetta. Le LISA et le LPC2E participent Ă la dĂ©finition des opĂ©rations et Ă lâinterprĂ©tation des rĂ©sultats de cet instrument. Les rĂ©centes observations rĂ©alisĂ©es par cet instrument permettent de confirmer la prĂ©sence de matiĂšre organique dans les grains comĂ©taires. Bien que les interprĂ©tations de ces observations soient encore prĂ©liminaires, il semble que la structure chimique de la matiĂšre organique observĂ©e ne soit pas celle Ă laquelle nous nous attendions. Aussi nous manquons de spectres de rĂ©fĂ©rence reprĂ©sentatifs des observations. NĂ©anmoins, nous suspectons actuellement quâil sâagisse dâune matiĂšre organique qui a Ă©tĂ© fortement chauffĂ©e et/ou irradiĂ©e. Lâobjectif de la thĂšse sera de caractĂ©riser le plus prĂ©cisĂ©ment possible la matiĂšre organique observĂ©e grĂące Ă lâinstrument COSIMA. Pour cela, de nouvelles synthĂšses de matiĂšre organique complexe seront effectuĂ©es en laboratoire (LISA) grĂące au dispositif expĂ©rimental du projet « OREGOC » (Origine et Evolution des Glaces et des composĂ©s Organiques ComĂ©taires) qui permet de photolyser dans lâultraviolet et de chauffer des mĂ©langes de glaces. Nous insisterons en particulier sur un dĂ©pĂŽt dâĂ©nergie plus consĂ©quent que ce que nous avons pu rĂ©aliser dans le passĂ©. Une fois produits, ces Ă©chantillons seront analysĂ©s grĂące aux deux instruments « sol » de COSIMA : le premier Ă©tant localisĂ© au LPC2E Ă OrlĂ©ans et le second au Max Planck Institute de Göttingen en Allemagne. Lâobjectif est naturellement de reproduire les observations rĂ©alisĂ©es sur des grains de la comĂšte 67P/Churyumov Gerasimenko Ă partir dâĂ©chantillons synthĂ©tiques afin de prĂ©ciser au mieux lâorigine de la matiĂšre organique comĂ©taire ainsi que son Ă©volution chimique jusquâĂ son Ă©jection du noyauComets are among the richest body in organic matter of Solar System. The remote sensing observations have already identified more than two dozen of simple organic molecules in the gas phase. Moreover, in situ exploration missions (Giotto, Vega-1 and Vega-2), as well as the sample return of the Stardust mission, have established that in addition to these relatively simple volatile molecules, a significant fraction of cometary carbonaceous material remain solid in the cometary grains. COSIMA (Cometary Secondary Ion Mass Analyzer) is a time of flight - secondary ion mass spectrometer on board the orbiter of the Rosetta mission. LISA and LPC2E participate to the definition of the operations and to the interpretation of the observations of this instrument. Recent observations performed with this instrument can confirm the presence of solid organic matter in the cometary grains. While the interpretations of these findings are still preliminary, it appears that the chemical structure of this organic matter is not the one that we were expecting. Thus, we lack of representative reference spectra. However, we suspect that the cometary organic material has been strongly heated and / or irradiated before the accretion of the cometary nucleus. The aim of the thesis is to describe as accurately as possible the organic matter observed thank to the COSIMA instrument. New synthesis of complex organic material synthesis will be performed in our laboratory (LISA) thank to the experimental setup named 'OREGOC' (French acronym for ORigin and Evolution of Ices and Cometary Organic matter) that allows ultraviolet photolysis and heating ice mixtures. We will particularly insist on a higher energy deposition during the photolysis that what we have achieved in the past. Once produced, these samples will be analyzed using the two âgroundâ instruments of COSIMA: the first being located at LPC2E Orleans and the second at the Max Planck Institute in Göttingen, Germany. The aim is naturally to reproduce the observations made on the grains of the comet 67P / Churyumov-Gerasimenko thank to synthetic samples to clarify the nature of the cometary organic matter and its chemical evolution since its synthesis to its ejection from the cometary nucleus
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