Direct Observation of Dynamic Lithium Diffusion Behavior in Nickel-Rich, LiNi0.8Mn0.1Co0.1O2 (NMC811) Cathodes Using Operando Muon Spectroscopy.

Ni-rich layered oxide cathode materials such as LiNi0.8Mn0.1Co0.1O2 (NMC811) are widely tipped as the next-generation cathodes for lithium-ion batteries. The NMC class offers high capacities but suffers an irreversible first cycle capacity loss, a result of slow Li+ diffusion kinetics at a low state of charge. Understanding the origin of these kinetic hindrances to Li+ mobility inside the cathode is vital to negate the first cycle capacity loss in future materials design. Here, we report on the development of operando muon spectroscopy (µSR) to probe the Å-length scale Li+ ion diffusion in NMC811 during its first cycle and how this can be compared to electrochemical impedance spectroscopy (EIS) and the galvanostatic intermittent titration technique (GITT). Volume-averaged muon implantation enables measurements that are largely unaffected by interface/surface effects, thus providing a specific characterization of the fundamental bulk properties to complement surface-dominated electrochemical methods. First cycle measurements show that the bulk Li+ mobility is less affected than the surface Li+ mobility at full depth of discharge, indicating that sluggish surface diffusion is the likely cause of first cycle irreversible capacity loss. Additionally, we demonstrate that trends in the nuclear field distribution width of the implanted muons during cycling correlate with those observed in differential capacity, suggesting the sensitivity of this µSR parameter to structural changes during cycling.

A Propensity-Matched Comparison of Ischemic Brain Lesions on Postprocedural MRI in Endovascular versus Open Carotid Artery Reconstruction.

(1) Study purpose: The aim of our prospective single-center, matched case-control study was to compare the number and volume of acute ischemic brain lesions following carotid endarterectomy (CEA) versus carotid artery stenting (CAS) using a propensity-matched design. (2) Methods: Carotid bifurcation plaques were analyzed by using VascuCAP software on CT angiography (CTA) images. The number and volume of acute and chronic ischemic brain lesions were assessed on MRI scans taken 12-48 h after the procedures. Propensity score-based matching was performed at a 1:1 ratio to compare the ischemic lesions on postinterventional MR. (3) Results: A total of 107 patients (CAS, N = 33; CEA, N = 74) were included in the study. There were significant differences in smoking (p = 0.003), total calcification plaque volume (p = 0.004), and lengths of the lesion (p = 0.045) between the CAS and CEA groups. Propensity score matching resulted in 21 matched pairs of patients. Acute ischemic brain lesions were detected in ten patients (47.6%) of the matched CAS group and in three patients (14.2%) in the matched CEA group (p = 0.02). The volume of acute ischemic brain lesions was significantly larger (p = 0.04) in the CAS group than in the CEA group. New ischemic brain lesions were not associated with neurological symptoms in either group. (4) Conclusions: Procedure-related new acute ischemic brain lesions occurred significantly more frequently in the propensity-matched CAS group.

p53 CRISPR Deletion Affects DNA Structure and Nuclear Architecture.

The TP53 gene is a key tumor suppressor. Although the tumor suppressor p53 was one of the first to be characterized as a transcription factor, with its main function potentiated by its interaction with DNA, there are still many unresolved questions about its mechanism of action. Here, we demonstrate a novel role for p53 in the maintenance of nuclear architecture of cells. Using three-dimensional (3D) imaging and spectral karyotyping, as well as super resolution microscopy of DNA structure, we observe significant differences in 3D telomere signatures, DNA structure and DNA-poor spaces as well gains or losses of chromosomes, between normal and tumor cells with CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)-deleted or wild-type TP53. Additionally, treatment with Nutlin-3 results in differences in nuclear architecture of telomeres in wild-type but not in p53 knockout MCF-7 (Michigan Cancer Foundation-7) cells. Nutlin-3 binds to the p53-binding pocket of mouse double minute 2 (MDM2) and blocks the p53-MDM2 interaction. Moreover, we demonstrate that another p53 stabilizing small molecule, RITA (reactivation of p53 and induction of tumor cell apoptosis), also induces changes in 3D DNA structure, apparently in a p53 independent manner. These results implicate p53 activity in regulating nuclear organization and, additionally, highlight the divergent effects of the p53 targeting compounds Nutlin-3 and RITA.

MYCN overexpression is associated with unbalanced copy number gain, altered nuclear location, and overexpression of chromosome arm 17q genes in neuroblastoma tumors and cell lines.

MYCN amplification and MYCN overexpression are poor prognostic factors in neuroblastoma. Tumors with unbalanced chromosome arm 17q gain are often associated with MYCN amplification; however, the relationship between chromosome 17 copy number status and MYCN expression is not known. We investigated the relationship between MYCN expression and chromosome 17 copy number, nuclear location, and gene expression. By performing dual-colored fluorescence in situ hybridization on 16 primary neuroblastomas, we found that those with unbalanced gain of 17q have high MYCN expression, those with no gain have medium expression, and those with numerical gain have low expression (P < 0.0001). We also found that the nuclear location of 17q correlates with chromosome 17 copy number status: copies in tumors with unbalanced gain and no gain of chromosome 17 occupy a more central location than those in tumors with balanced gain (P < 0.0001). We show that a more central nuclear location of 17q coincides with increased expression of genes found within this chromosome arm. To further understand the association between MYCN expression and chromosome 17, we overexpressed MYCN in two low-expressing MYCN cell lines, SHEP and GIMEN. We found that both cell lines had an unbalanced gain of chromosome 17q, a more central nuclear location of the region and increased expression of the 17q genes. Therefore, this study indicates, for the first time, a functional relationship between MYCN overexpression and the gain of 17q in neuroblastoma.