Individual Domain Level Research Articles

Imaging current control of magnetization in Fe3GeTe2 with a widefield nitrogen-vacancy microscope

Van der Waals (vdW) magnets are appealing candidates for realising spintronic devices that exploit current control of magnetization (e.g. switching or domain wall motion), but so far experimental demonstrations have been sparse, in part because of challenges associated with imaging the magnetization in these systems. Widefield nitrogen-vacancy (NV) microscopy allows rapid, quantitative magnetic imaging across entire vdW flakes, ideal for capturing changes in the micromagnetic structure due to an electric current. Here we use a widefield NV microscope to study the effect of current injection in thin flakes (∼10 nm) of the vdW ferromagnet Fe3GeTe2 (FGT). We first observe current-reduced coercivity on an individual domain level, where current injection in FGT causes substantial reduction in the magnetic field required to locally reverse the magnetisation. We then explore the possibility of current-induced domain-wall motion, and provide preliminary evidence for such a motion under relatively low current densities, suggesting the existence of strong current-induced torques in our devices. Our results illustrate the applicability of widefield NV microscopy to imaging spintronic phenomena in vdW magnets, highlight the possibility of efficient magnetization control by direct current injection without assistance from an adjacent conductor, and motivate further investigations of the effect of currents in FGT and other vdW magnets.

Patient Perceived Disability after an Interdisciplinary Treatment Approach for Chronic Musculoskeletal Pain Syndromes

<h3>Research Objectives</h3> To investigate the perceived disability of child and the family impact with chronic Musculoskeletal Pain Syndrome before and after receiving an intense, interdisciplinary treatment approach. <h3>Design</h3> The design is a retrospective look at the pre and post assessment measures in a cohort of 119. <h3>Setting</h3> The study setting is full day pain program within a private institution for children and adolescents. <h3>Participants</h3> Patients who participated in the program between 2015 and 2019, retrospective chart review was performed to abstract data on patients' Functional Disability Index (FDI) and PedsQL. <h3>Interventions</h3> Daily occupational and physical therapy, weekly psychology (CBT-model), social work services, school re-integration planning, and art and music therapies. OT included strengthening, functional activities and desensitization for 3 hours a day and PT included strength and endurance training 2 hours a day. <h3>Main Outcome Measures</h3> The outcome measures were the PedsQL and FDI. The PedsQL is a brief health-related quality of life measure looking at physical, emotional, social, and school functioning in children (Varni, J.W., Seid, M. & Kurtin, P.S. 2001). The FDI is a well-established and frequently used measure of physical functioning and disability in adolescents with chronic pain (Kashikar-Zuck, et al 2011). <h3>Results</h3> Patients were given the PedsQL on their first and last day and the FDI during their OT initial and discharge evaluations. <h3>Conclusions</h3> An intense, Interdisciplinary treatment approach for chronic musculoskeletal pain syndromes can reduce a patients perceived level of physical disability and measure their quality of life in the four domains mentioned. In the cohort of 119, the difference between FDI scores at admission vs FDI scores at discharge was assessed using Wilcoxon Signed Rank test, which found to be statistically significant with the p-value < 0.0001. In the cohort of 119, we observed that PedsQL inventory total scores as well as individual domains' scores were improved (higher scores) at discharge vs admission. These changes were statistically significant (all p-values < 0.05), indicating improvement in HRQoL (overall and at individual domain level) at discharge in comparison to admission. <h3>Author(s) Disclosures</h3> None.

857 Long-term outcomes in children treated with laser therapy for twin-twin transfusion syndrome

In the U.S., patients who undergo fetoscopic laser photocoagulation (FLP) for twin-twin transfusion syndrome (TTTS) may travel great distances for care. Many cannot return to study sites for evaluation due to geographic location. We used internet-based Ages and Stages Questionnaire (ASQ-3) surveys to collect parent-reported outcomes in children treated for TTTS. Survey of patients residing in 23 different U.S. states who underwent FLP for TTTS or TAPS at a single center from 2013 until 2019. Patients with ≥ 1 neonatal survivor were invited to complete the ASQ online if their child was between 2-60 months corrected age. Repeat survey was performed after 12 months. ASQ scores indicating typical development or improvement after 1 year were classified “Favorable”. Scores indicating atypical development or decline were classified “Unfavorable”. Comparative statistics were performed including stratified analysis of results by ASQ domains. 276 mothers met inclusion criteria, of which the ASQ was completed by 81 patients. After 12 months, 61 patients were eligible for repeat ASQ, of which 31 responded (follow-up rate of 51%, total 58 repeat child assessments). Median pediatric age of responders at initial assessment was 20.0 (IQR, 8.5 – 39.0) months. Among non-responders, children were older at follow-up (p <0.001) and more likely to be from the Southern U.S. (p=0.002).(Table 1) Among children who repeated the ASQ, early gestational age and the loss of a co-twin was associated with “Unfavorable” composite scores. Similar findings occurred at the individual domain level assessment of Gross Motor, Problem Solving and Personal-Social skills.(Table 2) This is the first successful attempt to use internet-based technology to assess long-term pediatric outcomes via the ASQ-3 in a U.S. cohort of children treated with FLP for TTTS. Prematurity and co-twin demise appear to be the greatest risk factors for abnormal childhood development.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

ProtCID: a data resource for structural information on protein interactions

Structural information on the interactions of proteins with other molecules is plentiful, and for some proteins and protein families, there may be 100s of available structures. It can be very difficult for a scientist who is not trained in structural bioinformatics to access this information comprehensively. Previously, we developed the Protein Common Interface Database (ProtCID), which provided clusters of the interfaces of full-length protein chains as a means of identifying biological assemblies. Because proteins consist of domains that act as modular functional units, we have extended the analysis in ProtCID to the individual domain level. This has greatly increased the number of large protein-protein clusters in ProtCID, enabling the generation of hypotheses on the structures of biological assemblies of many systems. The analysis of domain families allows us to extend ProtCID to the interactions of domains with peptides, nucleic acids, and ligands. ProtCID provides complete annotations and coordinate sets for every cluster.

An inter-professional approach to train and evaluate communication accuracy and completeness during the delivery of nurse-physician student handoffs

Abstract Importance The I-PASS training bundle has been shown to improve communication errors during medical student and resident handoffs but has not been explored in the context of interprofessional care. Objective We examined the impact of an interprofessional I-PASS training on communication accuracy and completeness during the delivery of nurse-physician student handoffs. Design, participants, and setting A pre-post comparative design was used to evaluate the differential impact of training on sixty-three first year nursing students and sixty-nine first year medical students, as part of an interprofessional curricular intervention, at an integrated university campus. Intervention The interprofessional I-PASS training was adapted from the existing I-PASS: Medical Student Workshop by a team of interprofessional faculty and presented to nursing and medical students. Main measures Simulated patient handoffs were used to assess communication performance prior to and following training. Evaluation involved the transcription and scoring of all verbal units delivered during the nurse-physician student handoffs based on four levels of information accuracy: correct, missing, erred, and omitted. Proportional changes in verbal units produced during pre and post-training encounters were compared at the combine total and individual domain levels based on training, student type, gender, previous handoff experience, and their interactions. Results Significant improvements in the proportions of correct, erred, and omitted verbal units at the combined total levels were observed across students, all p Discussion I-PASS training can improve communication accuracy and completeness during nurse-physician student handoffs. An event-based tool and coding procedure allowed for the identification of differential training impact based on individual handoff domains and provider demographics.

Cotranslocational processing of the protein substrate calmodulin by an AAA+ unfoldase occurs via unfolding and refolding intermediates

Protein remodeling by AAA+ enzymes is central for maintaining proteostasis in a living cell. However, a detailed structural description of how this is accomplished at the level of the substrate molecules that are acted upon is lacking. Here, we combine chemical cross-linking and methyl transverse relaxation-optimized NMR spectroscopy to study, at atomic resolution, the stepwise unfolding and subsequent refolding of the two-domain substrate calmodulin by the VAT AAA+ unfoldase from Thermoplasma acidophilum By engineering intermolecular disulphide bridges between the substrate and VAT we trap the substrate at different stages of translocation, allowing structural studies throughout the translocation process. Our results show that VAT initiates substrate translocation by pulling on intrinsically unstructured N or C termini of substrate molecules without showing specificity for a particular amino acid sequence. Although the B1 domain of protein G is shown to unfold cooperatively, translocation of calmodulin leads to the formation of intermediates, and these differ on an individual domain level in a manner that depends on whether pulling is from the N or C terminus. The approach presented generates an atomic resolution picture of substrate unfolding and subsequent refolding by unfoldases that can be quite different from results obtained via in vitro denaturation experiments.

Molecular Arrangement in Self-Assembled Azobenzene-Containing Thiol Monolayers at the Individual Domain Level Studied through Polarized Near-Field Raman Spectroscopy

6-[4-(phenylazo)phenoxy]hexane-1-thiol self-assembled monolayers deposited on a gold surface form domain-like structures possessing a high degree of order with virtually all the molecules being identically oriented with respect to the surface plane. We show that, by using polarized near-field Raman spectroscopy, it is possible to derive the Raman scattering tensor of the ordered layer and consequently, the in-plane molecular orientation at the individual domain level. More generally, this study extends the application domain of the near-field Raman scattering selection rules from crystals to ordered organic structures.

Investigating Protein Aggregation using Segmental Isotope Labeling and 2D IR Spectroscopy

Protein misfolding and aggregation are important processes in numerous human diseases, but the detailed structural changes that occur therein evade traditional crystallographic and NMR-based techniques. Rapid-scan 2D IR spectroscopy, combined with heavy isotope labeling, provides information on local secondary structure and coupling between IR chromophores, which can be used to study systems that aggregate in vitro on a timescale of minutes to hours. Recently, we have utilized single-position 1-13C=18O labels to develop a detailed kinetic model of the aggregation of synthetic hIAPP, a 37 AA peptide implicated in type II diabetes mellitus. Here we demonstrate a segmental, 13C labeling approach to the study the much larger human gammaD-crystallin, a 173 AA eye lens protein that aggregates via an unknown mechanism during cataract formation. Using bacterial expression and native chemical ligation, we have generated a gammaD-crystallin variant in which the highly similar N- and C-terminal domains are uniformly enriched in 12C and 13C, respectively. This results two well-resolved diagonal peaks in the 2D IR spectrum of the natively folded protein, with a separation of ∼40 cm−1. Aggregation under acidic conditions results in spectral changes consistent with amyloid fiber formation in the C-terminal domain and unfolding of the N-terminal domain, with evidence of interaction between the two based on the presence of cross-peaks. The structural model we propose, currently resolved at the level of individual domains, is nonetheless the most detailed available for a gammaD-crystallin aggregate to date. We anticipate that the method described will be broadly applicable to difficult systems including many aggregating, natively unstructured, or membrane-associated proteins.

Three-step multi-domain BEM solver for nonhomogeneous material problems

A three-step solution technique is presented for solving two-dimensional (2D) and three-dimensional (3D) nonhomogeneous material problems using the multi-domain boundary element method. The discretized boundary element formulation expressed in terms of normalized displacements and tractions is written for each sub-domain. The first step is to eliminate internal variables at the individual domain level. The second step is to eliminate boundary unknowns defined over nodes used only by the domain itself. And the third step is to establish the system of equations according to the compatibility of displacements and equilibrium of tractions at common interface nodes. Discontinuous elements are utilized to model the traction discontinuity across corner nodes. The distinct feature of the three-step solver is that only interface displacements are unknowns in the final system of equations and the coefficient matrix is blocked sparse. As a result, large-scale 3D problems can be solved efficiently. Three numerical examples for 2D and 3D problems are given to demonstrate the effectiveness of the presented technique.

Recognition of local glycoprotein misfolding by the ER folding sensor UDP-glucose:glycoprotein glucosyltransferase.

The endoplasmic reticulum (ER) contains a stringent quality control system that ensures the correct folding of newly synthesized proteins to be exported via the secretory pathway. In this system UDP-Glc:glycoprotein glucosyltransferase (GT) serves as a glycoprotein specific folding sensor by specifically glucosylating N-linked glycans in misfolded glycoproteins thus retaining them in the calnexin/calreticulin chaperone cycle. To investigate how GT senses the folding status of glycoproteins, we generated RNase B heterodimers consisting of a folded and a misfolded domain. Only glycans linked to the misfolded domain were found to be glucosylated, indicating that the enzyme recognizes folding defects at the level of individual domains and only reglucosylates glycans directly attached to a misfolded domain. The result was confirmed with complexes of soybean agglutinin and misfolded thyroglobulin.