Perseverance’s Mastcam-Z instrument provides high-resolution stereo and multispectral images with a unique combination of spatial resolution, spatial coverage, and wavelength coverage along the ...rover’s traverse in Jezero crater, Mars. Images reveal rocks consistent with an igneous (including volcanic and/or volcaniclastic) and/or impactite origin and limited aqueous alteration, including polygonally fractured rocks with weathered coatings; massive boulder-forming bedrock consisting of mafic silicates, ferric oxides, and/or iron-bearing alteration minerals; and coarsely layered outcrops dominated by olivine. Pyroxene dominates the iron-bearing mineralogy in the fine-grained regolith, while olivine dominates the coarse-grained regolith. Solar and atmospheric imaging observations show significant intra- and intersol variations in dust optical depth and water ice clouds, as well as unique examples of boundary layer vortex action from both natural (dust devil) and Ingenuity helicopter–induced dust lifting. High-resolution stereo imaging also provides geologic context for rover operations, other instrument observations, and sample selection, characterization, and confirmation.
Renal function is an important predictor of survival in cirrhosis and liver transplantation. GFR estimates using serum cystatin C (CysC) are proposed as better predictors of renal function than ones ...on the basis of serum creatinine (Cr). Our aims were: (1) evaluate correlations between serum CysC and different methods of creatinine measurements; (2) compare CysC and Cr GFR formulas with (51)Cr-EDTA; and (3) evaluate liver-related parameters potentially influencing GFR.
254 blood samples in 65 patients with cirrhosis correlating CysC with four Cr methods were used; another 74 patients comparing (51)Cr-EDTA GFR to Modification of Diet in Renal Disease and Larsson and Hoek formulas for CysC were also included. Agreement was assessed using Bland-Altman plots and concordance correlation coefficients. Multivariate linear regression analysis was used for GFR predictors.
Serum CysC correlated modestly with O'Leary modified Jaffe, compensated kinetic Jaffe, enzymatic creatinine, and standard kinetic Jaffe 0.72/0.71/0.72/0.72 (all P < 0.001). Bland-Altman agreement with (51)Cr-EDTA GFR was poor; the best agreement was Modification of Diet in Renal Disease (concordance 0.61; 95% CI, 0.47 to 0.71); the worst agreement was the Hoek formula (concordance 0.46; 95% CI, 0.27 to 0.61). A new GFR formula including the Child-Pugh score improved the accuracy of Cr GFR formulas compared with (51)Cr-EDTA GFR.
Estimated GFR in cirrhosis is not better with CysC formulas compared with creatinine ones: specific formulas may be necessary.
α-Dystrobrevin (DB), a cytoplasmic component of the dystrophin–glycoprotein complex, is found throughout the sarcolemma of muscle cells. Mice lacking αDB exhibit muscular dystrophy, defects in ...maturation of neuromuscular junctions (NMJs) and, as shown here, abnormal myotendinous junctions (MTJs). In normal muscle, alternative splicing produces two main αDB isoforms, αDB1 and αDB2, with common NH2-terminal but distinct COOH-terminal domains. αDB1, whose COOH-terminal extension can be tyrosine phosphorylated, is concentrated at the NMJs and MTJs. αDB2, which is not tyrosine phosphorylated, is the predominant isoform in extrajunctional regions, and is also present at NMJs and MTJs. Transgenic expression of either isoform in αDB−/− mice prevented muscle fiber degeneration; however, only αDB1 completely corrected defects at the NMJs (abnormal acetylcholine receptor patterning, rapid turnover, and low density) and MTJs (shortened junctional folds). Site-directed mutagenesis revealed that the effectiveness of αDB1 in stabilizing the NMJ depends in part on its ability to serve as a tyrosine kinase substrate. Thus, αDB1 phosphorylation may be a key regulatory point for synaptic remodeling. More generally, αDB may play multiple roles in muscle by means of differential distribution of isoforms with distinct signaling or structural properties.
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The brain is "immunologically privileged," in part because class I and II MHC antigens are not normally present on glia or neurons. However, under certain conditions such as transplantation, glial ...cells express MHC proteins at levels sufficient for glia to become targets of immune responses. Cultured astrocytes expressing very low levels of MHC class I protein are killed efficiently by MHC class I antigen-specific CTL. Mouse brain allografts, however, are rejected by CD4+ T cells that are likely to be class II MHC-specific. The level of expression of MHC class II antigen needed to trigger specific killing of astrocytes by CD4+ T cells, independent of exogenous antigen, has not been studied. We examined the role of glial class II MHC in the lysis of cultured neonatal mouse astrocytes by an alloreactive murine CD4+ CTL alone. IFN-gamma induced functionally relevant increases in MHC class II antigen on target cells. Astrocytes were lysed by the CD4+ clone only when class II MHC antigens reached levels readily detectable by flow cytometry. MHC class II expression and lysis increased when astrocytes were coincubated with IFN-gamma and TNF-alpha. Conversely, lysis decreased when class II expression was downregulated by IFN-alpha/beta or dbcAMP. Cytolysis by CD4+ clones was blocked by antibodies to CD4 and LFA-1 on T cells, and to ICAM-1 and class II molecules on astrocytes. The role of LFA-1 in CD4+ cell-mediated lysis was greater than that of LFA-1/ICAM-1 in CD8+ T cell-mediated lysis. CD4+ cells may lyse activated astrocytes when the immune privilege of the brain is compromised as in transplantation, tumors, and inflammatory diseases.
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