Substitution for aspartic acid by glycine at position 614 in the spike (S) protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of the ongoing pandemic, appears to facilitate rapid viral spread. The G614 variant has now replaced the D614-carrying virus as the dominant circulating strain. We report here cryo-EM structures of a full-length S trimer carrying G614, which adopts three distinct prefusion conformations differing primarily by the position of one receptor-binding domain (RBD). A loop disordered in the D614 S trimer wedges between domains within a protomer in the G614 spike. This added interaction appears to prevent premature dissociation of the G614 trimer, effectively increasing the number of functional spikes and enhancing infectivity. The loop transition may also modulate structural rearrangements of S protein required for membrane fusion. These findings extend our understanding of viral entry and suggest an improved immunogen for vaccine development.

Cavernous malformations (CMs) consist of dilated vascular channels that have a characteristic appearance on MRI. CMs are usually found intracranially, although such lesions can also affect the spinal cord. Individuals with CMs can present with epilepsy and focal neurological deficits or acute intracranial hemorrhage. In many cases, however, patients with such lesions are asymptomatic at diagnosis. Furthermore, several natural history studies have documented that a substantial proportion of asymptomatic CMs follow a benign course. Surgical resection is recommended for CMs that require intervention. Radiosurgery has been advocated for many lesions that have not been easily accessible by conventional surgery. The outcomes of radiosurgery and surgery for deep lesions, however, vary widely between studies, rendering treatment recommendations for such CMs difficult to make. In addition to reviewing the literature, this article will discuss the current understanding of lesion pathophysiology and explore the controversial issues in the management of CMs, such as when to use radiosurgery or surgery in deep-seated lesions, the treatment of epilepsy, and the safety of anticoagulation.

Mesenchymal stem cells (MSCs) are ideal for cell-based therapy in various inflammatory diseases because of their immunosuppressive and tissue repair properties. Moreover, their immunosuppressive properties and low immunogenicity contribute to a reduced or weakened immune response elicited by the implantation of allogeneic MSCs compared with other cell types. Therefore, implantation of allogeneic MSCs may be a promising cell-based therapy. In this review, we first summarize the unique advantages of allogeneic MSCs for therapeutic applications. Second, we critically analyze the factors influencing their therapeutic effects, including administration routes, detection time-points, disease models, differentiation of MSCs in vivo, and timing and dosage of MSC administration. Finally, current approaches to allogeneic MSC application are discussed. In conclusion, allogeneic MSCs are a promising option because of their low immunogenicity and immunosuppressive and tissue repair capabilities. Further investigations are needed to enhance the consistency and efficacy of MSCs when used as a cell-based therapy in inflammatory diseases as well as for tissue repair.

Abstract-The importance of proteasomes in governing the intracellular protein degradation process has been increasingly recognized. Recent investigations indicate that proteasome complexes may exist in a species-and cell-type-specific fashion. To date, despite evidence linking impaired protein degradation to cardiac disease phenotypes, virtually nothing is known regarding the molecular composition, function, or regulation of cardiac proteasomes. We have taken a functional proteomic approach to characterize 26S proteasomes in the murine heart. Multidimensional chromatography was used to obtain highly purified and functionally viable cardiac 20S and 19S proteasome complexes, which were subjected to electrophoresis and tandem mass spectrometry analyses. Our data revealed complex molecular organization of cardiac 26S proteasomes, some of which are similar to what were reported in yeast, whereas others exhibit contrasting features that have not been previously identified in other species or cell types. At least 36 distinct subunits (17 of 20S and 19 of 19S) are coexpressed and assembled as 26S proteasomes in this vital cardiac organelle, whereas the expression of PA200 and 11S subunits were detected with limited participation in the 26S complexes. The 19S subunits included a new alternatively spliced isoform of Rpn10 (Rpn10b) along with its primary isoform (Rpn10a). Immunoblotting and immunocytochemistry verified the expression of key ␣ and ␤ subunits in cardiomyocytes. The expression of 14 constitutive ␣ and ␤ subunits in parallel with their three inducible subunits (␤1i, ␤2i, and ␤5i) in the normal heart was not expected; these findings represent a distinct level of structural complexity of cardiac proteasomes, significantly different from that of yeast and human erythrocytes. Furthermore, liquid chromatography/tandem mass spectroscopy characterized 3 distinct types of post-translational modifications including (1) N-terminal acetylation of 19S subunits (Rpn1, Rpn5, Rpn6, Rpt3, and Rpt6) and 20S subunits (␣2, ␣5, ␣7, ␤3, and ␤4); (2) N-terminal myristoylation of a 19S subunit (Rpt2); and (3) phosphorylation of 20S subunits (eg, ␣7)). Taken together, this report presents the first comprehensive characterization of cardiac 26S proteasomes, providing critical structural and proteomic information fundamental to our future understanding of this essential protein degradation system in the normal and diseased myocardium. T he proteasome is a key proteolytic enzymatic system governing the degradation of majority intracellular proteins. 1 Recent studies implicate proteasomes in cardiac diseases. [2][3][4][5][6][7][8][9][10][11] Proteasome inhibitors are widely used in cancer therapy, however, their impact on cardiac function remains unclear; investigations in the heart have reported conflicting results. 2-4,12 A major contributing factor to these controversies is the lack of information pertaining to the structural organization and protein composition of cardiac proteasomes, therefore prohibiting the identification of mol...

Cerebral cavernous malformation (CCM) is a common autosomal dominant disorder characterized by venous sinusoids that predispose to intracranial hemorrhage. CCM is genetically heterogeneous, with loci at 7q, 7p and 3q. Mutations in KRIT1 account for all cases linked to 7q (CCM1), but the pathogenesis of CCM is not understood. Krev Interaction Trapped 1 (krit1) was originally identified through its interaction with the Ras-family GTPase krev1/rap1a in a two-hybrid screen, inferring a role in GTPase signaling cascades. We demonstrated additional 5'-coding exons for krit1, extending the N-terminus by 207 amino acids compared to the previously reported protein. Remarkably, by two-hybrid analysis and co-immunoprecipitation, full-length krit1 fails to interact with krev1/rap1a but shows strong interaction with integrin cytoplasmic domain-associated protein-1 (icap1). Icap1 binds to a NPXY motif in the cytoplasmic domain of beta1 integrin and participates in beta1-mediated cell adhesion and migration. The novel N-terminus of krit1 contains a NPXY motif that it is required for icap1 interaction. Like beta1 integrin, krit1 interacts with the 200 amino acid isoform of icap1 (icap1alpha), but not a 150 amino acid form that results from alternative splicing (icap1beta). In a competition assay, induced expression of krit1 diminishes the interaction between icap1alpha and beta1 integrin. Taken together, these data suggest that beta1 integrin and krit1 compete for the same site on icap1alpha, perhaps constituting a regulatory mechanism. Loss-of-function KRIT1 mutations, as observed in CCM1, would shift the balance with predicted consequences for endothelial cell performance during integrin beta1-dependent angiogenesis.

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Linkage analyses have identified several candidate regions, a significant step in defining the genetic etiology of this disorder.

WHAT'S KNOWN ON THIS SUBJECT:Research has shown that dishware size influences self-served portion sizes and meal intake in adults. In children, larger bowls led children to request more food, but whether larger dishware affects children' s self-served portions or intake at meals is not known. WHAT THIS STUDY ADDS:We assessed the effect of increasing dishware size on self-served portions and intake in young children. Larger plates and bowls resulted in larger self-served portions, and indirectly promoted greater intake, emphasizing the importance of age-appropriate dishware.abstract OBJECTIVES: Dishware size is thought to influence eating behaviors, but effects on children' s self-served portion sizes and intakes have not been studied. We aimed to evaluate whether larger dishware increased children' s self-served portion sizes and intake during meals. METHODS:A within-subjects experimental design was used to test the effects of dishware size (ie, plates and bowls) on children' s self-served portion sizes and intakes in a naturalistic setting. Subjects were predominantly African American elementary school-aged children (n = 42) observed on repeated occasions during school lunch. Children served themselves an entree and side dishes using either child-or adult-size dishware, which represented a 100% increase in the surface area of plates and volume of bowls across conditions. Condition order was randomly assigned and counterbalanced across 2 first-grade classrooms. Entrées of amorphous and unit form were evaluated on separate days. Fruit and vegetable side dishes were evaluated at each meal. Fixed portions of milk and bread were provided at each meal. RESULTS:Children served more energy (mean = 90.1 kcal, SE = 29.4 kcal) when using adult-size dishware. Adult-size dishware promoted energy intake indirectly, where every additional calorie served resulted in a 0.43-kcal increase in total energy intakes at lunch (t = 7.72, P = .001).CONCLUSIONS: Children served themselves more with larger plates and bowls and consumed nearly 50% of the calories that they served. This provides new evidence that children' s self-served portion sizes are influenced by size-related facets of their eating environments, which, in turn, may influence children' s energy intake. Pediatrics