The acute phase of sepsis is characterized by a strong inflammatory reaction. At later stages in some patients, immunoparalysis may be encountered, which is associated with a poor outcome. By ...transcriptional and metabolic profiling of human patients with sepsis, we found that a shift from oxidative phosphorylation to aerobic glycolysis was an important component of initial activation of host defense. Blocking metabolic pathways with metformin diminished cytokine production and increased mortality in systemic fungal infection in mice. In contrast, in leukocytes rendered tolerant by exposure to lipopolysaccharide or after isolation from patients with sepsis and immunoparalysis, a generalized metabolic defect at the level of both glycolysis and oxidative metabolism was apparent, which was restored after recovery of the patients. Finally, the immunometabolic defects in humans were partially restored by therapy with recombinant interferon-γ, which suggested that metabolic processes might represent a therapeutic target in sepsis.
Oxygen administration is uniformly used in emergency and intensive care medicine and has life-saving potential in critical conditions. However, excessive oxygenation also has deleterious properties ...in various pathophysiological processes and consequently both clinical and translational studies investigating hyperoxia during critical illness have gained increasing interest. Reactive oxygen species are notorious by-products of hyperoxia and play a pivotal role in cell signaling pathways. The effects are diverse, but when the homeostatic balance is disturbed, reactive oxygen species typically conserve a vicious cycle of tissue injury, characterized by cell damage, cell death, and inflammation. The most prominent symptoms in the abundantly exposed lungs include tracheobronchitis, pulmonary edema, and respiratory failure. In addition, absorptive atelectasis results as a physiological phenomenon with increasing levels of inspiratory oxygen. Hyperoxia-induced vasoconstriction can be beneficial during vasodilatory shock, but hemodynamic changes may also impose risk when organ perfusion is impaired. In this context, oxygen may be recognized as a multifaceted agent, a modifiable risk factor, and a feasible target for intervention. Although most clinical outcomes are still under extensive investigation, careful titration of oxygen supply is warranted in order to secure adequate tissue oxygenation while preventing hyperoxic harm.
Animal–microbe mutualisms are typically maintained by vertical symbiont transmission or partner choice. A third mechanism, screening of high-quality symbionts, has been predicted in theory, but ...empirical examples are rare. Here we demonstrate that ambrosia beetles rely on ethanol within host trees for promoting gardens of their fungal symbiont and producing offspring. Ethanol has long been known as the main attractant for many of these fungus-farming beetles as they select host trees in which they excavate tunnels and cultivate fungal gardens. More than 300 attacks by Xylosandrus germanus and other species were triggered by baiting trees with ethanol lures, but none of the foundresses established fungal gardens or produced broods unless tree tissues contained in vivo ethanol resulting from irrigation with ethanol solutions. More X. germanus brood were also produced in a rearing substrate containing ethanol. These benefits are a result of increased food supply via the positive effects of ethanol on food-fungus biomass. Selected Ambrosiella and Raffaelea fungal isolates from ethanol-responsive ambrosia beetles profited directly and indirectly by (i) a higher biomass on medium containing ethanol, (ii) strong alcohol dehydrogenase enzymatic activity, and (iii) a competitive advantage over weedy fungal garden competitors (Aspergillus, Penicillium) that are inhibited by ethanol. As ambrosia fungi both detoxify and produce ethanol, they may maintain the selectivity of their alcohol-rich habitat for their own purpose and that of other ethanol-resistant/producing microbes. This resembles biological screening of beneficial symbionts and a potentially widespread, unstudied benefit of alcohol-producing symbionts (e.g., yeasts) in other microbial symbioses.
Rimmed grooves, lineations and elongate craters around Mare Imbrium shape much of the nearside Moon. This pattern was coined the Imbrium Sculpture, and it was originally argued that it must have been ...formed by a giant oblique (~30°) impact, a conclusion echoed by later studies. Some investigators, however, noticed that many elements of the Imbrium Sculpture are not radial to Imbrium, thereby implicating an endogenic or structural origin. Here we use these non-radial trends to conclude that the Imbrium impactor was a proto-planet (half the diameter of Vesta), once part of a population of large proto-planets in the asteroid belt. Such independent constraints on the sizes of the Imbrium and other basin-forming impactors markedly increase estimates for the mass in the asteroid belt before depletion caused by the orbital migration of Jupiter and Saturn. Moreover, laboratory impact experiments, shock physics codes and the groove widths indicate that multiple fragments (up to 2% of the initial diameter) from each oblique basin-forming impactor, such as the one that formed Imbrium, should have survived planetary collisions and contributed to the heavy impact bombardment between 4.3 and 3.8 billion years ago.
New experiments predict that Ceres should be extensively contaminated with meteoritic debris derived from the asteroid belt. All types of impactors likely contribute to the contamination. Ceres may ...accrete debris more efficiently if it is ice‐rich because of enhanced projectile survival and retention in porous ice targets. Experiments indicate that if a silicate regolith lag protects subsurface ice, then some of the projectile should be injected into the regolith during high‐angle impacts, thereby hiding part of the projectile component from view. If impacts excavate ice, sublimation will gradually concentrate projectile relics into a surficial lag. In contrast, if the near‐surface lacks ice, then accreted meteoritic debris should be distributed throughout a vertically mixed regolith. High‐resolution images may reveal pristine projectile relics lining some crater floors. Moreover, we predict that the surface of Ceres is not exclusively endogenic and may be dominated by delivered exogenic debris.
Key Points
Impact experiments reveal how efficiently icy targets retain impactors
Ice content of Ceres will change extent and expression of projectile component
Ceres is likely heavily contaminated by all types of impactors
•We analytically and numerically model the effects of a comet impact at the Moon.•Cometary impacts produce widespread zones of heating and particle mobilization.•Transient magnetic fields exceed ...Earth’s surface field by four orders of magnitude.•We revisit the cometary impact model for lunar swirl formation with new results.•Swirls are consistent with thermal, mechanical, magnetic processing by comet impact.
Relatively recent cometary impacts at the Moon could leave unique traces of their origins: high impact velocities and volatile abundances, combined with the presence of a dust- and ice-laden coma, may thermally and mechanically process the lunar surface in ways distinct from the impact of an asteroid. Here we analytically and numerically assess the consequences of a cometary impact at the Moon by considering the combined effects of a collision by the nucleus and inner coma. Our results show that cometary impacts entrain the finest fraction of lunar soil grains (<10μm) over regional scales (∼100–1000km), produce large masses of vaporized material, and likely generate transient magnetic fields that could exceed the Earth’s surface field strength by a factor of 104. This combination of processes is consistent with a mechanism to generate lunar swirls: the diffuse, meandering disturbances in brightness and regolith texture that curl across much of the lunar far-side and are also commonly (but not exclusively) associated with magnetic anomalies. Previous observations of swirl features indicate that bright regions also possess a peculiar, altered regolith structure, which can be produced by the removal of fine soil grains. Regional scouring by an impacting comet explains both the structure and albedo variations: large dynamic pressures entrain the smallest grains within a near-surface flow of dusty plasma, disrupting the backscattering, “fairy-castle” structure of lunar soils in equilibrium with the airless environment. The resulting surface is brightened by compaction of the previously open, porous macrostructure. Darker lanes observed within swirl regions are interpreted as possible melt and/or vapor deposits. Finally, the intense magnetic fields generated during high-speed cometary impacts provide an explanation for correlations between swirl locations and magnetic anomalies.
Emerging evidence has shown the potential risks of arterial hyperoxia, but the lack of a clinical definition and methodologic limitations hamper the interpretation and clinical relevance of previous ...studies. Our purpose was to evaluate previously used and newly constructed metrics of arterial hyperoxia and systematically assess their association with clinical outcomes in different subgroups in the ICU.
Observational cohort study.
Three large tertiary care ICUs in the Netherlands.
A total of 14,441 eligible ICU patients.
None.
In total, 295,079 arterial blood gas analyses, including the PaO2, between July 2011 and July 2014 were extracted from the patient data management system database. Data from all admissions with more than one PaO2 measurement were supplemented with anonymous demographic and admission and discharge data from the Dutch National Intensive Care Evaluation registry. Mild hyperoxia was defined as PaO2 between 120 and 200 mm Hg; severe hyperoxia as PaO2 greater than 200 mm Hg. Characteristics of existing and newly constructed metrics for arterial hyperoxia were examined, and the associations with hospital mortality (primary outcome), ICU mortality, and ventilator-free days and alive at day 28 were retrospectively analyzed using regression models in different subgroups of patients. Severe hyperoxia was associated with higher mortality rates and fewer ventilator-free days in comparison to both mild hyperoxia and normoxia for all metrics except for the worst PaO2. Adjusted effect estimates for conditional mortality were larger for severe hyperoxia than for mild hyperoxia. This association was found both within and beyond the first 24 hours of admission and was consistent for large subgroups. The largest point estimates were found for the exposure identified by the average PaO2, closely followed by the median PaO2, and these estimates differed substantially between subsets. Time spent in hyperoxia showed a linear and positive relationship with hospital mortality.
Our results suggest that we should limit the PaO2 levels of critically ill patients within a safe range, as we do with other physiologic variables. Analytical metrics of arterial hyperoxia should be judiciously considered when interpreting and comparing study results and future studies are needed to validate our findings in a randomized fashion design.
Impact angle plays a significant role in determining the fate of the projectile. In this study, we use a suite of hypervelocity impact experiments to reveal how impact angle affects the preservation, ...distribution, and physical state of projectile residues in impact craters. Diverse types of projectiles, including amorphous silicates, crystalline silicates, and aluminum, in two sizes (6.35 and 12.7 mm), were launched into blocks of copper or 6061 aluminum at speeds between 1.9 and 5.7 km s−1. Crater interiors preserve projectile residues in all cases, including conditions relevant to the asteroid belt. These residues consist of projectile fragments or projectile‐rich glasses, depending on impact conditions. During oblique impacts at 30° and 45°, the uprange crater wall preserves crystalline fragments of the projectile. The fragments of water‐rich projectiles such as antigorite remain hydrated. Several factors contribute to enhanced preservation on the uprange wall, including a weaker shock uprange, uprange acceleration as the shock reflects off the back of the projectile, and rapid quenching of melts along the projectile–target interface. These findings have two broader implications. First, the results suggest a new collection strategy for flyby sample return missions. Second, these results predict that the M‐type asteroid Psyche should bear exogenic, impactor‐derived debris.
EPOXI at Comet Hartley 2 A'Hearn, Michael F.; Belton, Michael J. S.; Delamere, W. Alan ...
Science (American Association for the Advancement of Science),
06/2011, Volume:
332, Issue:
6036
Journal Article
Peer reviewed
Understanding how comets work—what drives their activity—is crucial to the use of comets in studying the early solar system. EPOXI (Extrasolar Planet Observation and Deep Impact Extended ...Investigation) flew past comet 103P/Hartley 2, one with an unusually small but very active nucleus, taking both images and spectra. Unlike large, relatively inactive nuclei, this nucleus is outgassing primarily because of CO 2 , which drags chunks of ice out of the nucleus. It also shows substantial differences in the relative abundance of volatiles from various parts of the nucleus.
•High-speed spectroscopy reveals the evolving vapor plume at different impact angles.•Quarter-space experiments track vapor inside the transient cavity below the surface.•Multiple views reveal ...rapidly evolving vapor phases in different directions.•Impact-generated vapor fills the transient cavity before being released above.•Results have implications for volatile delivery and release on planetary bodies.
High-speed spectra of hypervelocity impacts at the NASA Ames Vertical Gun Range (AVGR) captured the rapidly evolving conditions of impact-generated vapor as a function of impact angle, viewpoint, and time (within the first 50μs). Impact speeds possible at the AVGR (<7km/s) are insufficient to induce significant vaporization in silicates, other than the high-temperature (but low-mass) jetting component created at first contact. Consequently, this study used powdered dolomite as a proxy for surveying the evolution and distribution of chemical constituents within much longer lasting vapor. Seven separate telescopes focused on different portions of the impact vapor plume and were connected through quartz fibers to two 0.35cm monochromaters. Quarter-space experiments reduced the thermal background and opaque phases due to condensing particles and heated projectile fragments while different exposure times isolated components passing through different the fields of view, both above and below the surface within the growing transient cavity. At early times (<5μs), atomic emission lines dominate the spectra. At later times, molecular emission lines dominate the composition of the vapor plume along a given direction. Layered targets and target mixtures isolated the source and reveal that much of the vaporization comes from the uppermost surface. Collisions by projectile fragments downrange also make significant contributions for impacts below 60° (from the horizontal). Further, impacts into mixtures of silicates with powdered dolomite reveal that frictional heating must play a role in vapor production. Such results have implications for processes controlling vaporization on planetary surfaces including volatile release, atmospheric evolution (formation and erosion), vapor generated by the Deep Impact collision, and the possible consequences of the Chicxulub impact.
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