A large topographic feature on the surface of the trans-Neptunian object (307261) 2002 MS4_4 measured from stellar occultations

This work aims at constraining the size, shape, and geometric albedo of the dwarf planet candidate 2002 MS4 through the analysis of nine stellar occultation events. Using multichord detection, we also studied the object's topography by analyzing the obtained limb and the residuals between observed chords and the best-fitted ellipse. We predicted and organized the observational campaigns of nine stellar occultations by 2002 MS4 between 2019 and 2022, resulting in two single-chord events, four double-chord detections, and three events with three to up to sixty-one positive chords. Using 13 selected chords from the 8 August 2020 event, we determined the global elliptical limb of 2002 MS4. The best-fitted ellipse, combined with the object's rotational information from the literature, constrains the object's size, shape, and albedo. Additionally, we developed a new method to characterize topography features on the object's limb. The global limb has a semi-major axis of 412 $\pm$ 10 km, a semi-minor axis of 385 $\pm$ 17 km, and the position angle of the minor axis is 121 $^\circ$ $\pm$ 16$^\circ$. From this instantaneous limb, we obtained 2002 MS4's geometric albedo and the projected area-equivalent diameter. Significant deviations from the fitted ellipse in the northernmost limb are detected from multiple sites highlighting three distinct topographic features: one 11 km depth depression followed by a 25$^{+4}_{-5}$ km height elevation next to a crater-like depression with an extension of 322 $\pm$ 39 km and 45.1 $\pm$ 1.5 km deep. Our results present an object that is $\approx$138 km smaller in diameter than derived from thermal data, possibly indicating the presence of a so-far unknown satellite. However, within the error bars, the geometric albedo in the V-band agrees with the results published in the literature, even with the radiometric-derived albedo

Effects of osmotic changes on the chemoreceptor cell of rat carotid body

The carotid body plays a crucial role in cardiorespiratory regulation. In the present study we investigated the effect of osmotic changes on cytoplasmic calcium concentration ([Ca2+]c) and pH (pHi) of isolated chemoreceptor cells of the rat carotid body. In CO2/HCO3−-buffered medium, reduction of osmolality from the control level of 300 mosmol kg−1 to 250–285 mosmol kg−1 resulted in a rise in [Ca2+]c, as measured with Indo-1, whereas elevation of osmolality to 350 mosmol kg−1 had no effect. The Ca2+ response required extracellular Ca2+ and was reduced by application of the L-type Ca2+ channel antagonist nifedipine (10 μm). The hyposmosis-induced Ca2+ response could be prevented by application of niflumic acid (300 μm), an inhibitor of the swelling-activated Cl− channel. In whole-cell patch-clamp experiments niflumic acid abolished the swelling-activated Cl− current but only slightly depressed the Ca2+ current. The inhibition of Ca2+ current by niflumic acid does not account for its action in preventing of hyposmosis-induced Ca2+ response, which seems to be initiated by Cl−-mediated depolarisation. Withdrawal of CO2/HCO3− also prevented the Ca2+ response. Reduction of the osmotic concentration by 50 mosmol kg−1 induced a small but sustained decrease in pHi, while elevation by 50 mosmol kg−1 had an inverse effect, as measured fluorimetrically with carboxy SNARF-1. Our conclusion is that in the rat chemoreceptor cell the activation of Cl− channels, e.g. by hyposmotic challenge, induces depolarisation, which, in turn, activates voltage-gated Ca2+ channels

A Self-Consistent Description of the Conformational Behavior of Chemically Denatured Proteins from NMR and Small Angle Scattering

Characterization of the conformational properties of unfolded proteins is essential for understanding the mechanisms of protein folding and misfolding. This information is also fundamental to determining the relationship between flexibility and function in the highly diverse families of intrinsically disordered proteins. Here we present a self-consistent model of conformational sampling of chemically denatured proteins in agreement with experimental data reporting on long-range distance distributions in unfolded proteins using small-angle x-ray scattering and nuclear magnetic resonance pulse-field gradient-based measurements. We find that standard statistical coil models, selected from folded protein databases with secondary structural elements removed, need to be refined to correct backbone dihedral angle sampling of denatured proteins, although they appear to be appropriate for intrinsically disordered proteins. For denatured proteins, pervasive increases in the sampling of more-extended regions of Ramachandran space {50°< ψ < 180°} throughout the peptide chain are found to be consistent with all experimental data. These observations are in agreement with previous conclusions derived from short-range nuclear magnetic resonance data from residual dipolar couplings, leading the way to a self-consistent description of denatured chains that is in agreement with short- and long-range data measured using both spectroscopic and scattering techniques

Altered monocyte CD44 expression in peripheral arterial disease is corrected by fish oil supplementation

Background and aims: CD44 and its splice variants can be expressed on all leukocytes, conferring adhesive properties and enhancing cellular recruitment to the endothelium during inflammation. CD44 expression is increased in inflammatory conditions such as rheumatoid arthritis and CD44 variant 3 (CD44v3) expression may be associated with inflammation. We have examined CD44 and CD44v3 expression on peripheral blood monocytes from patients with peripheral arterial disease (PAD) and healthy controls. We have also examined the effect of fish oil supplementation on these markers. Methods and results: CD44 and CD44v3 were assessed at baseline and following dietary supplementation with fish oil for 12weeks in both PAD and control groups. Monocytes from PAD patients had higher CD44 expression than those from controls (median intensity fluorescence (MIF): 480+/-278 vs 336+/-251 (mean+/-SD); p&lt;0.001). Following 12weeks dietary supplementation with fish oil, CD44 expression was reduced in PAD patients (MIF: 480+/-278 vs 427+/-262; p=0.05) but not in controls (336+/-251 vs 355+/-280; ns). Monocyte CD44v3 expression was lower in cultured monocytes from PAD patients compared to those from controls (0.15+/-0.15 vs 0.22+/-0.14 OD units; p&lt;0.02). This was increased in the PAD group following fish oil supplementation (0.15+/-0.14 to 0.27+/-0.23 OD units; p&lt;0.001). Conclusion: Monocyte CD44 and CD44v3 expression are altered in arterial disease but are returned towards levels seen in control subjects by dietary fish oil supplementation<br/