In Vivo Detection of Inflammation Using Pegylated Iron Oxide Particles Targeted at E-Selectin A Multimodal Approach Using MR Imaging and EPR Spectroscopy

peer reviewedObjectives: Ultrasmall particles of iron oxide (USPIO) possess superparamagnetic properties and are used as negative contrast agent in magnetic resonance imaging (MRI) because of their strong T-2 and T-2* effects. Besides this method, electron paramagnetic resonance (EPR) offers the unique capability to quantify these particles. The objective of this study was to evaluate a molecular marker for non invasive diagnosis and monitoring of inflammation. During inflammation cell adhesion molecules such as E-selectin are expressed on the endothelial cell surface. An E-selectin ligand was coupled to pegylated USPIO particles. Materials and Methods: Inflammation was induced by intramuscular injection of Freund's Complete Adjuvant in male NMRI mice. After intravenous injection of grafted or ungrafted USPIO particles, iron concentration in inflamed muscles was quantified ex vivo by X-band EPR. Particle accumulation was also assessed in vivo by L-Band EPR, as well as by T-2-Weighted MRI. Results: We determined the mean iron oxide concentration in inflamed muscles after injection of grafted or ungrafted UPSIO particles, which was 0.8% and 0.4% of the initially injected dose, respectively. By L-band EPR, we observed that the concentration of the grafted USPIO particles in inflamed muscles was twice higher than for the ungrafted particles. Using MRI experiments, a higher signal loss was clearly observed in the inflamed muscle when grafted particles were injected in comparison with the ungrafted particles. Conclusion: Even taking into account a non specific accumulation of iron oxides, the targeting of USPIO particles with E-selectin ligands significantly improved the sensitivity of detection of inflamed tissues

The Far Side of Mars: Two Distant Marsquakes Detected by InSight

For over three Earth years the Marsquake Service has been analyzing the data sent back from the Seismic Experiment for Interior Structure¿the seismometer placed on the surface of Mars by NASA¿s InSight lander. Although by October 2021, the Mars seismic catalog included 951 events, until recently all these events have been assessed as lying within a radius of 100° of InSight. Here we report two distant events that occurred within days of each other, located on the far side of Mars, giving us our first glimpse into Mars¿ core shadow zone. The first event, recorded on 25 August 2021 (InSight sol 976), shows clear polarized arrivals that we interpret to be PP and SS phases at low frequencies and locates to Valles Marineris, 146° ± 7° from InSight. The second event, occurring on 18 September 2021 (sol 1000), has significantly more broadband energy with emergent PP and SS arrivals, and a weak phase arriving before PP that we interpret as Pdiff¿. Considering uncertain pick times and poorly constrained travel times for Pdiff¿, we estimate this event is at a distance between 107° and 147° from InSight. With magnitudes of MMaw 4.2 and 4.1, respectively, these are the largest seismic events recorded so far on Mars.Anna C. Horleston, Jessica C. E. Irving,and Nicholas A. Teanby are funded by the UKSA under Grant Numbers ST/R002096/1, ST/W002523/1, and ST/W002515/1.Nikolaj L. Dahmen, Cecilia Duran, Géraldine Zenhäusern, andSimon C. Stähler would like to acknowledge support from Eidgenössische Technische Hochschule (ETH) through the ETH+ funding scheme (ETH+02 19-1: “Planet Mars”). The French coauthors acknowledge the funding support provided by CNES and the Agence Nationale de la Recherche (ANR-19-CE31-0008-08 MAGIS) for SEIS operation and SEIS Science analysis. Alexander E. Stott acknowledges the French Space Agency CNES and ANR (ANR-19-CE31-0008-08). Caroline Beghein and Jiaqi Li were supported by NASA InSight Participating Scientist Program (PSP) Grant Number 80NSSC18K1679. This article is InSight Contribution Number 236

First observations of core-Transiting seismic phases on Mars

We present the first observations of seismic waves propagating through the core of Mars. These observations, made using seismic data collected by the InSight geophysical mission, have allowed us to construct the first seismically constrained models for the elastic properties of Mars core. We observe core-Transiting seismic phase SKS from two farside seismic events detected on Mars and measure the travel times of SKS relative to mantle traversing body waves. SKS travels through the core as a compressional wave, providing information about bulk modulus and density. We perform probabilistic inversions using the core-sensitive relative travel times together with gross geophysical data and travel times from other, more proximal, seismic events to seek the equation of state parameters that best describe the liquid iron-Alloy core. Our inversions provide constraints on the velocities in Mars core and are used to develop the first seismically based estimates of its composition. We show that models informed by our SKS data favor a somewhat smaller (median core radius = 1,780 to 1,810 km) and denser (core density = 6.2 to 6.3 g/cm3) core compared to previous estimates, with a P-wave velocity of 4.9 to 5.0 km/s at the core mantle boundary, with the composition and structure of the mantle as a dominant source of uncertainty. We infer from our models that Mars core contains a median of 20 to 22 wt% light alloying elements when we consider sulfur, oxygen, carbon, and hydrogen. These data can be used to inform models of planetary accretion, composition, and evolution.W.B.B., K.J.H, and M.P.P. were supported by the NASA InSight mission and funds from the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the NASA (80NM0018D0004). V.L. and N.C.S. were supported by funding from NASA grant 80NSSC18K1628 and NASA SSERVI Cooperative Agreement 80NSSC19M0216. C.D., A.K., D.G., S.C., J.C., D.K., and S.C.S. acknowledge support from ETH through the ETH+ funding scheme (ETH+02 19-1: “Planet Mars”). The Marsquake Service (MQS) operations at ETH are supported by ETH Research grant ETH-06 17-02. M.D., H.S., D.A., R.G., T.K., P.L., E.S., and Z.X. acknowledge the support of CNES for SEIS operation and science analysis, with an additional support of ANR (MAGIS, ANR-19-CE31-0008-08). H.S., T.K., P.L. E.S., and Z.X. additionally acknowledge the support from the IdEx Université Paris Cité (ANR-18-IDEX-0001). M.D. and H.S. were granted access to the HPC resources of CINES under the allocation A0110413017, made by the GENCI. Numerical computations were partly performed on the S-CAPAD/DANTE platform, IPGP, France. D.A. has received funding from the European Research Council under the European Union’s Horizon 2020 research and innovation program (grant agreement 724690); D.A. also acknowledges the support by CNES, focused on the SEIS instrument of the InSight mission. A.R. was financially supported by the Belgian PRODEX program managed by the European Space Agency in collaboration with the Belgian Federal Science Policy Office. E.B. and Q.H. were funded by NASA InSight PSP grant #80NSSC18K1680. C.B. and J.L. were funded by NAS

Internal deformation of the subducted Nazca slab inferred from seismic anisotropy

Within oceanic lithosphere a fossilized fabric is often preserved originating from the time of plate formation. Such fabric is thought to form at the mid-ocean ridge when olivine crystals align with the direction of plate spreading1, 2. It is unclear, however, whether this fossil fabric is preserved within slabs during subduction or overprinted by subduction-induced deformation. The alignment of olivine crystals, such as within fossil fabrics, can generate anisotropy that is sensed by passing seismic waves. Seismic anisotropy is therefore a useful tool for investigating the dynamics of subduction zones, but it has so far proved difficult to observe the anisotropic properties of the subducted slab itself. Here we analyse seismic anisotropy in the subducted Nazca slab beneath Peru and find that the fast direction of seismic wave propagation aligns with the contours of the slab. We use numerical modelling to simulate the olivine fabric created at the mid-ocean ridge, but find it is inconsistent with our observations of seismic anisotropy in the subducted Nazca slab. Instead we find that an orientation of the olivine crystal fast axes aligned parallel to the strike of the slab provides the best fit, consistent with along-strike extension induced by flattening of the slab during subduction (A. Kumar et al., manuscript in preparation). We conclude that the fossil fabric has been overprinted during subduction and that the Nazca slab must therefore be sufficiently weak to undergo internal deformation

Surface waves and crustal structure on Mars

We detected surface waves from two meteorite impacts on Mars. By measuring group velocity dispersion along the impact-lander path, we obtained a direct constraint on crustal structure away from the InSight lander. The crust north of the equatorial dichotomy had a shear wave velocity of approximately 3.2 kilometers per second in the 5- to 30-kilometer depth range, with little depth variation. This implies a higher crustal density than inferred beneath the lander, suggesting either compositional differences or reduced porosity in the volcanic areas traversed by the surface waves. The lower velocities and the crustal layering observed beneath the landing site down to a 10-kilometer depth are not a global feature. Structural variations revealed by surface waves hold implications for models of the formation and thickness of the martian crust.D.K., S.C., D.G., J.C., C.D., A. K., S.C.S., N.D., and G.Z. were supported by the ETH+ funding scheme (ETH+02 19-1: “Planet Mars”). Marsquake Service operations at ETH Zürich were supported by ETH Research grant ETH-06 17-02. N.C.S. and V.L. were supported by NASA PSP grant no. 80NSSC18K1628. Q.H. and E.B. are funded by NASA grant 80NSSC18K1680. C.B. and J.L. were supported by NASA InSight PSP grant no. 80NSSC18K1679. S.D.K. was supported by NASA InSight PSP grant no. 80NSSC18K1623. P.L., E.B., M.D., H.S., E.S., M.W., Z.X., T.W., M.P., R.F.G. were supported by CNES and the Agence Nationale de la Recherche (ANR-19-CE31-0008-08 MAGIS) for SEIS operation and SEIS Science analysis. A.H., C.C. and W.T.P. were supported by the UKSA under grant nos. ST/R002096/1, ST/ W002523/1 and ST/V00638X/1. Numerical computations of McMC Approach 2 were performed on the S-CAPAD/DANTE platform (IPGP, France) and using the HPC resources of IDRIS under the allocation A0110413017 made by GENCI. A.H. was supported by the UKSA under grant nos. ST/R002096/1 and ST/W002523/1. F.N. was supported by InSight PSP 80NSSC18K1627. I.J.D. was supported by NASA InSight PSP grant no. 80NSSC20K0971. L.V.P. was funded by NASANNN12AA01C with subcontract JPL-1515835. The research was carried out in part by W.B.B., M.G. and M.P.P. at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004)Peer reviewe

The Lunar Geophysical Network Mission

The National Academy’s current Planetary Decadal Survey (NRC, 2011) prioritizes a future Lunar Geophysical Network (LGN) mission to gather new information that will permit us to better determine how the overall composition and structure of the Moon inform us about the initial differentiation and subsequent evolution of terrestrial planets

Constraints on the shallow elastic and anelastic structure of Mars from InSight seismic data

Mars’s seismic activity and noise have been monitored since January 2019 by the seismometer of the InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) lander. At night, Mars is extremely quiet; seismic noise is about 500 times lower than Earth’s microseismic noise at periods between 4 s and 30 s. The recorded seismic noise increases during the day due to ground deformations induced by convective atmospheric vortices and ground-transferred wind-generated lander noise. Here we constrain properties of the crust beneath InSight, using signals from atmospheric vortices and from the hammering of InSight’s Heat Flow and Physical Properties (HP3) instrument, as well as the three largest Marsquakes detected as of September 2019. From receiver function analysis, we infer that the uppermost 8–11 km of the crust is highly altered and/ or fractured. We measure the crustal diffusivity and intrinsic attenuation using multiscattering analysis and find that seismic attenuation is about three times larger than on the Moon, which suggests that the crust contains small amounts of volatiles

Initial results from the InSight mission on Mars

NASA’s InSight (Interior exploration using Seismic Investigations, Geodesy and Heat Transport) mission landed in Elysium Planitia on Mars on 26 November 2018. It aims to determine the interior structure, composition and thermal state of Mars, as well as constrain present-day seismicity and impact cratering rates. Such information is key to understanding the differentiation and subsequent thermal evolution of Mars, and thus the forces that shape the planet’s surface geology and volatile processes. Here we report an overview of the first ten months of geophysical observations by InSight. As of 30 September 2019, 174 seismic events have been recorded by the lander’s seismometer, including over 20 events of moment magnitude Mw = 3–4. The detections thus far are consistent with tectonic origins, with no impact-induced seismicity yet observed, and indi- cate a seismically active planet. An assessment of these detections suggests that the frequency of global seismic events below approximately Mw = 3 is similar to that of terrestrial intraplate seismic activity, but there are fewer larger quakes; no quakes exceeding Mw = 4 have been observed. The lander’s other instruments—two cameras, atmospheric pressure, temperature and wind sensors, a magnetometer and a radiometer—have yielded much more than the intended supporting data for seismometer noise characterization: magnetic field measurements indicate a local magnetic field that is ten-times stronger than orbital estimates and meteorological measurements reveal a more dynamic atmosphere than expected, hosting baroclinic and gravity waves and convective vortices. With the mission due to last for an entire Martian year or longer, these results will be built on by further measurements by the InSight lander