A Compact Dispersive Refocusing Rowland Circle X-ray Emission Spectrometer for Laboratory, Synchrotron, and XFEL Applications

X-ray emission spectroscopy is emerging as an important complement to x-ray absorption fine structure spectroscopy, providing a characterization of the occupied electronic density of states local to the species of interest. Here, we present details of the design and performance of a compact x-ray emission spectrometer that uses a dispersive refocusing Rowland (DRR) circle geometry to achieve excellent performance for the 2 - 2.5 keV energy range. The DRR approach allows high energy resolution even for unfocused x-ray sources. This property enables high count rates in laboratory studies, comparable to those of insertion-device beamlines at third-generation synchrotrons, despite use of only a low-powered, conventional x-ray tube. The spectrometer, whose overall scale is set by use of a 10-cm diameter Rowland circle and a new small-pixel CMOS x-ray camera, is easily portable to synchrotron or x-ray free electron beamlines. Photometrics from measurements at the Advanced Light Source show somewhat higher overall instrumental efficiency than prior systems based on less tightly curved analyzer optics. In addition, the compact size of this instrument lends itself to future multiplexing to gain large factors in net collection efficiency, or its implementation in controlled gas gloveboxes either in the lab or in an endstation.Comment: Submitted, Review of Scientific Instrument

Mavacamten Treatment for Symptomatic Obstructive Hypertrophic Cardiomyopathy: Interim Results From the MAVA-LTE Study, EXPLORER-LTE Cohort.

This study was funded by Bristol Myers Squibb, Princeton, New Jersey, USA. Bristol Myers Squibb’s policy on data sharing is available online at https://www.bms.com/researchers-and-partners/clinicaltrials-and-research/disclosure-commitment.html. Dr Rader has received consulting fees from Medtronic, Bristol Myers Squibb, and ReCor Medical. Dr Ore˛ziak has received personal fees from Bristol Myers Squibb. Dr Saberi has received personal fees from Bristol Myers Squibb. Dr Fermin has received consulting fees from Alnylam, Eidos Therapeutics, Bristol Myers Squibb, and Pfizer. Dr Wheeler has received personal fees and research support from Bristol Myers Squibb. Dr Garcia-Pavia has received consulting and speaking fees from Bristol Myers Squibb, Rocket Pharmaceuticals, and Cytokinetics and speaking fees from Bristol Myers Squibb and Cytokinetics. Dr Zwas has received personal fees from Bristol Myers Squibb. Dr Masri has received grants from Akcea, Pfizer, and Ultromics and consulting fees from Alnylam, Cytokinetics, Eidos Therapeutics, Ionis, and Pfizer. Dr Owens has received consulting fees from Bristol Myers Squibb, Cytokinetics, and Pfizer. Dr Hegde serves on the faculty of the Cardiovascular Imaging Core Laboratory at Brigham and Women’s Hospital, and her institution has received payments for her consulting work from Bristol Myers Squibb. Dr Seidler has received consulting fees or honoraria for lectures from Bristol Myers Squibb and Cytokinetics. Dr Balaratnam and Dr Sehnert are employees of Bristol Myers Squibb and own stock of Bristol Myers Squibb. Shawna Fox is an employee of IQVIA, a partner providing statistics services to Bristol Myers Squibb. Dr Olivotto has received grants from Amicus, Boston Scientific, Bristol Myers Squibb, Cytokinetics, Genzyme, and Menarini International and consulting fees from Amicus, Cytokinetics, Genzyme, MS Pharma, Rocket Pharmaceuticals, and Tenaya Therapeutics.BACKGROUND Data assessing the long-term safety and efficacy of mavacamten treatment for symptomatic obstructive hypertrophic cardiomyopathy are needed. OBJECTIVES The authors sought to evaluate interim results from the EXPLORER-Long Term Extension (LTE) cohort of MAVA-LTE (A Long-Term Safety Extension Study of Mavacamten in Adults Who Have Completed EXPLORER-HCM; NCT03723655). METHODS After mavacamten or placebo withdrawal at the end of the parent EXPLORER-HCM (Clinical Study to Evaluate Mavacamten [MYK-461] in Adults With Symptomatic Obstructive Hypertrophic Cardiomyopathy; NCT03470545), patients could enroll in MAVA-LTE. Patients received mavacamten 5 mg once daily; adjustments were made based on site-read echocardiograms. RESULTS Between April 9, 2019, and March 5, 2021, 231 of 244 eligible patients (94.7%) enrolled in MAVA-LTE (mean age: 60 years; 39% female). At data cutoff (August 31, 2021) 217 (93.9%) remained on treatment (median time in study: 62.3 weeks; range: 0.3-123.9 weeks). At 48 weeks, patients showed improvements in left ventricular outflow tract (LVOT) gradients (mean change ± SD from baseline: resting: -35.6 ± 32.6 mm Hg; Valsalva: -45.3 ± 35.9 mm Hg), N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels (median: -480 ng/L; Q1-Q3: -1,104 to -179 ng/L), and NYHA functional class (67.5% improved by ≥1 class). LVOT gradients and NT-proBNP reductions were sustained through 84 weeks in patients who reached this timepoint. Over 315 patient-years of exposure, 8 patients experienced an adverse event of cardiac failure, and 21 patients had an adverse event of atrial fibrillation, including 11 with no prior history of atrial fibrillation. Twelve patients (5.2%) developed transient reductions in site-read echocardiogram left ventricular ejection fraction of <50%, resulting in temporary treatment interruption; all recovered. Ten patients discontinued treatment due to treatment-emergent adverse events. CONCLUSIONS Mavacamten treatment showed clinically important and durable improvements in LVOT gradients, NT-proBNP levels, and NYHA functional class, consistent with EXPLORER-HCM. Mavacamten treatment was well tolerated over a median 62-week follow-up.S

Structure-based inhibitors halt prion-like seeding by Alzheimer’s disease–and tauopathy–derived brain tissue samples

In Alzheimer's disease (AD) and tauopathies, tau aggregation accompanies progressive neurodegeneration. Aggregated tau appears to spread between adjacent neurons and adjacent brain regions by prion-like seeding. Hence, inhibitors of this seeding offer a possible route to managing tauopathies. Here, we report the 1.0 Å resolution micro-electron diffraction structure of an aggregation-prone segment of tau with the sequence SVQIVY, present in the cores of patient-derived fibrils from AD and tauopathies. This structure illuminates how distinct interfaces of the parent segment, containing the sequence VQIVYK, foster the formation of distinct structures. Peptide-based fibril-capping inhibitors designed to target the two VQIVYK interfaces blocked proteopathic seeding by patient-derived fibrils. These VQIVYK inhibitors add to a panel of tau-capping inhibitors that targets specific polymorphs of recombinant and patient-derived tau fibrils. Inhibition of seeding initiated by brain tissue extracts differed among donors with different tauopathies, suggesting that particular fibril polymorphs of tau are associated with certain tauopathies. Donors with progressive supranuclear palsy exhibited more variation in inhibitor sensitivity, suggesting that fibrils from these donors were more polymorphic and potentially vary within individual donor brains. Our results suggest that a subset of inhibitors from our panel could be specific for particular disease-associated polymorphs, whereas inhibitors that blocked seeding by extracts from all of the tauopathies tested could be used to broadly inhibit seeding by multiple disease-specific tau polymorphs. Moreover, we show that tau-capping inhibitors can be transiently expressed in HEK293 tau biosensor cells, indicating that nucleic acid–based vectors can be used for inhibitor delivery

Dosing and safety profile of aficamten in symptomatic obstructive hypertrophic cardiomyopathy: results from from SEQUOIA‐HCM

Background: Aficamten, a novel cardiac myosin inhibitor, reversibly reduces cardiac hypercontractility in obstructive hypertrophic cardiomyopathy. We present a prespecified analysis of the pharmacokinetics, pharmacodynamics, and safety of aficamten in SEQUOIA‐HCM (Safety, Efficacy, and Quantitative Understanding of Obstruction Impact of Aficamten in HCM). Methods and Results: A total of 282 patients with obstructive hypertrophic cardiomyopathy were randomized 1:1 to daily aficamten (5–20 mg) or placebo between February 1, 2022, and May 15, 2023. Aficamten dosing targeted the lowest effective dose for achieving site‐interpreted Valsalva left ventricular outflow tract gradient &lt;30 mm Hg with left ventricular ejection fraction (LVEF) ≥50%. End points were evaluated during titration (day 1 to week 8), maintenance (weeks 8–24), and washout (weeks 24–28), and included major adverse cardiac events, new‐onset atrial fibrillation, implantable cardioverter‐defibrillator discharges, LVEF &lt;50%, and treatment‐emergent adverse events. At week 8, 3.6%, 12.9%, 35%, and 48.6% of patients achieved 5‐, 10‐, 15‐, and 20‐mg doses, respectively. Baseline characteristics were similar across groups. Aficamten concentration increased by dose and remained stable during maintenance. During the treatment period, LVEF decreased by −0.9% (95% CI, −1.3 to −0.6) per 100 ng/mL aficamten exposure. Seven (4.9%) patients taking aficamten underwent per‐protocol dose reduction for site‐interpreted LVEF &lt;50%. There were no treatment interruptions or heart failure worsening for LVEF &lt;50%. No major adverse cardiovascular events were associated with aficamten, and treatment‐emergent adverse events were similar between treatment groups, including atrial fibrillation. Conclusions: A site‐based dosing algorithm targeting the lowest effective aficamten dose reduced left ventricular outflow tract gradient with a favorable safety profile throughout SEQUOIA‐HCM

A new era for understanding amyloid structures and disease

The aggregation of proteins into amyloid fibrils and their deposition into plaques and intracellular inclusions is the hallmark of amyloid disease. The accumulation and deposition of amyloid fibrils, collectively known as amyloidosis, is associated with many pathological conditions that can be associated with ageing, such as Alzheimer disease, Parkinson disease, type II diabetes and dialysis-related amyloidosis. However, elucidation of the atomic structure of amyloid fibrils formed from their intact protein precursors and how fibril formation relates to disease has remained elusive. Recent advances in structural biology techniques, including cryo-electron microscopy and solid-state NMR spectroscopy, have finally broken this impasse. The first near-atomic-resolution structures of amyloid fibrils formed in vitro, seeded from plaque material and analysed directly ex vivo are now available. The results reveal cross-β structures that are far more intricate than anticipated. Here, we describe these structures, highlighting their similarities and differences, and the basis for their toxicity. We discuss how amyloid structure may affect the ability of fibrils to spread to different sites in the cell and between organisms in a prion-like manner, along with their roles in disease. These molecular insights will aid in understanding the development and spread of amyloid diseases and are inspiring new strategies for therapeutic intervention

Half a century of amyloids: past, present and future

Amyloid diseases are global epidemics with profound health, social and economic implications and yet remain without a cure. This dire situation calls for research into the origin and pathological manifestations of amyloidosis to stimulate continued development of new therapeutics. In basic science and engineering, the cross-ß architecture has been a constant thread underlying the structural characteristics of pathological and functional amyloids, and realizing that amyloid structures can be both pathological and functional in nature has fuelled innovations in artificial amyloids, whose use today ranges from water purification to 3D printing. At the conclusion of a half century since Eanes and Glenner's seminal study of amyloids in humans, this review commemorates the occasion by documenting the major milestones in amyloid research to date, from the perspectives of structural biology, biophysics, medicine, microbiology, engineering and nanotechnology. We also discuss new challenges and opportunities to drive this interdisciplinary field moving forward. This journal i

Dual-energy CT texture analysis with machine learning for the evaluation and characterization of cervical lymphadenopathy

Purpose: To determine whether machine learning assisted-texture analysis of multi-energy virtual monochromatic image (VMI) datasets from dual-energy CT (DECT) can be used to differentiate metastatic head and neck squamous cell carcinoma (HNSCC) lymph nodes from lymphoma, inflammatory, or normal lymph nodes. Materials and methods: A retrospective evaluation of 412 cervical nodes from 5 different patient groups (50 patients in total) having undergone DECT of the neck between 2013 and 2015 was performed: (1) HNSCC with pathology proven metastatic adenopathy, (2) HNSCC with pathology proven benign nodes (controls for (1)), (3) lymphoma, (4) inflammatory, and (5) normal nodes (controls for (3) and (4)). Texture analysis was performed with TexRAD® software using two independent sets of contours to assess the impact of inter-rater variation. Two machine learning algorithms (Random Forests (RF) and Gradient Boosting Machine (GBM)) were used with independent training and testing sets and determination of accuracy, sensitivity, specificity, PPV, NPV, and AUC. Results: In the independent testing (prediction) sets, the accuracy for distinguishing different groups of pathologic nodes or normal nodes ranged between 80 and 95%. The models generated using texture data extracted from the independent contour sets had substantial to almost perfect agreement. The accuracy, sensitivity, specificity, PPV, and NPV for correctly classifying a lymph node as malignant (i.e. metastatic HNSCC or lymphoma) versus benign were 92%, 91%, 93%, 95%, 87%, respectively. Conclusion: Machine learning assisted-DECT texture analysis can help distinguish different nodal pathology and normal nodes with a high accuracy

Resonant inelastic X‐ray scattering using a miniature dispersive Rowland refocusing spectrometer

X-ray absorption spectroscopy (XAS) beamlines worldwide are steadily increasing their emphasis on full photon-in/photon-out spectroscopies, such as resonant inelastic X-ray scattering (RIXS), resonant X-ray emission spectroscopy (RXES) and high energy resolution fluorescence detection XAS (HERFD-XAS). In such cases, each beamline must match the choice of emission spectrometer to the scientific mission of its users. Previous work has recently reported a miniature tender X-ray spectrometer using a dispersive Rowland refocusing (DRR) geometry that functions with high energy resolution even with a large X-ray spot size on the sample [Holden et al. (2017). Rev. Sci. Instrum. 88, 073904]. This instrument has been used in the laboratory in multiple studies of non-resonant X-ray emission spectroscopy using a conventional X-ray tube, though only for preliminary measurements at a low-intensity microfocus synchrotron beamline. This paper reports an extensive study of the performance of a miniature DRR spectrometer at an unfocused wiggler beamline, where the incident monochromatic flux allows for resonant studies which are impossible in the laboratory. The results support the broader use of the present design and also suggest that the DRR method with an unfocused beam could have important applications for materials with low radiation damage thresholds and that would not survive analysis on focused beamlines

Stimulatory Effects of Mesenchymal Stem Cells on cKit +

RATIONALE: Culture expanded cells originating from cardiac tissue that express the cell surface receptor cKit are undergoing clinical testing as a cell source for heart failure and congenital heart disease. While accumulating data support that mesenchymal stem cells (MSCs) enhance the efficacy of cardiac cKit(+) cells (CSCs), the underlying mechanism for this synergistic effect remain incompletely understood. OBJECTIVE: To test the hypothesis that MSCs stimulate endogenous CSCs to proliferate, migrate, and differentiate via the SDF1/CXCR4 and SCF/cKit pathways. METHODS AND RESULTS: Using genetic lineage-tracing approaches we show that in the postnatal murine heart, cKit(+) cells proliferate, migrate, and form cardiomyocytes, but not endothelial cells. CSCs exhibit marked chemotactic and proliferative responses when co-cultured with MSCs but not cardiac stromal cells. Antagonism of the CXCR4 pathway with AMD3100 inhibited MSC-induced CSC chemotaxis but stimulated CSC cardiomyogenesis (p<0.0001). Furthermore, MSCs enhanced CSC proliferation via the SCF/cKit and SDF1/CXCR4 pathways (p<0.0001). CONCLUSIONS: Together these findings show that MSCs exhibit profound, yet differential, effects upon CSC migration, proliferation and differentiation, and suggest a mechanism underlying the improved cardiac regeneration associated with combination therapy using CSCs and MSCs. These findings have important therapeutic implications for cell-based therapy strategies that employ mixtures of CSCs and MSCs

Hyperexcitable Substantia Nigra Dopamine Neurons in PINK1- and HtrA2/Omi-Deficient Mice

The electrophysiological properties of substantia nigra pars compacta (SNC) dopamine neurons can influence their susceptibility to degeneration in toxin-based models of Parkinson's disease (PD), suggesting that excitotoxic and/or hypoactive mechanisms may be engaged during the early stages of the disease. It is unclear, however, whether the electrophysiological properties of SNC dopamine neurons are affected by genetic susceptibility to PD. Here we show that deletion of PD-associated genes, PINK1 or HtrA2/Omi, leads to a functional reduction in the activity of small-conductance Ca2+-activated potassium channels. This reduction causes SNC dopamine neurons to fire action potentials in an irregular pattern and enhances burst firing in brain slices and in vivo. In contrast, PINK1 deletion does not affect firing regularity in ventral tegmental area dopamine neurons or substantia nigra pars reticulata GABAergic neurons. These findings suggest that changes in SNC dopamine neuron excitability may play a role in their selective vulnerability in PD