Streamlining the Analysis of Proteins from Snake Venom.

Investigating snake venom is necessary for developing new treatments for envenoming and harnessing the therapeutic potential that lies within venom toxins. Despite considerable efforts in previous research, several technical challenges remain for characterizing the individual components within such complex mixtures. Here, we present native and top-down mass spectrometry (MS) workflows that enable the analysis of individual venom proteins within complex mixtures and showcase the utility of these methodologies on King cobra (Ophiophagus hannah) venom. First, we coupled ion mobility spectrometry for separation and electron capture dissociation for charge reduction to resolve highly convoluted mass spectra containing multiple proteins with masses ranging from 55 to 127 kDa. Next, we performed a top-down glycomic analysis of a 25.5 kDa toxin, showing that this protein contains a fucosylated complex glycan. Finally, temperature-controlled nanoelectrospray mass spectrometry facilitated the top-down sequence analysis of a ß-cardiotoxin, which cannot be fragmented by collisional energy due to its disulfide bond pattern. The work presented here demonstrates the applicability of new and promising MS methods for snake venom analysis.

Effectiveness and cost-effectiveness of online recorded recovery narratives in improving quality of life for people with non-psychotic mental health problems: a pragmatic randomized controlled trial.

Narratives describing first-hand experiences of recovery from mental health problems are widely available. Emerging evidence suggests that engaging with mental health recovery narratives can benefit people experiencing mental health problems, but no randomized controlled trial has been conducted as yet. We developed the Narrative Experiences Online (NEON) Intervention, a web application providing self-guided and recommender systems access to a collection of recorded mental health recovery narratives (n=659). We investigated whether NEON Intervention access benefited adults experiencing non-psychotic mental health problems by conducting a pragmatic parallel-group randomized trial, with usual care as control condition. The primary endpoint was quality of life at week 52 assessed by the Manchester Short Assessment (MANSA). Secondary outcomes were psychological distress, hope, self-efficacy, and meaning in life at week 52. Between March 9, 2020 and March 26, 2021, we recruited 1,023 participants from across England (the target based on power analysis was 994), of whom 827 (80.8%) identified as White British, 811 (79.3%) were female, 586 (57.3%) were employed, and 272 (26.6%) were unemployed. Their mean age was 38.4±13.6 years. Mood and/or anxiety disorders (N=626, 61.2%) and stress-related disorders (N=152, 14.9%) were the most common mental health problems. At week 52, our intention-to-treat analysis found a significant baseline-adjusted difference of 0.13 (95% CI: 0.01-0.26, p=0.041) in the MANSA score between the intervention and control groups, corresponding to a mean change of 1.56 scale points per participant, which indicates that the intervention increased quality of life. We also detected a significant baseline-adjusted difference of 0.22 (95% CI: 0.05-0.40, p=0.014) between the groups in the score on the "presence of meaning" subscale of the Meaning in Life Questionnaire, corresponding to a mean change of 1.1 scale points per participant. We found an incremental gain of 0.0142 quality-adjusted life years (QALYs) (95% credible interval: 0.0059 to 0.0226) and a £178 incremental increase in cost (95% credible interval: -£154 to £455) per participant, generating an incremental cost-effectiveness ratio of £12,526 per QALY compared with usual care. This was lower than the £20,000 per QALY threshold used by the National Health Service in England, indicating that the intervention would be a cost-effective use of health service resources. In the subgroup analysis including participants who had used specialist mental health services at baseline, the intervention both reduced cost (-£98, 95% credible interval: -£606 to £309) and improved QALYs (0.0165, 95% credible interval: 0.0057 to 0.0273) per participant as compared to usual care. We conclude that the NEON Intervention is an effective and cost-effective new intervention for people experiencing non-psychotic mental health problems.

Solution and Gas-Phase Stability of DNA Junctions from Temperature-Controlled Electrospray Ionization and Surface-Induced Dissociation.

DNA three-way junction (TWJ) structures transiently form during key cellular processes such as transcription, replication, and DNA repair. Despite their significance, the thermodynamics of TWJs, including the influence of strand length, base pair composition, and ligand binding on TWJ stability and dissociation mechanisms, are poorly understood. To address these questions, we interfaced temperature-controlled nanoelectrospray ionization mass spectrometry (TC-nESI-MS) with a cyclic ion mobility spectrometry (cIMS) instrument that was also equipped with a surface-induced dissociation (SID) stage. This novel combination allowed us to investigate the structural intermediates of three TWJ complexes and examine the effects of GC base pairs on their dissociation pathways. We found that two TWJ-specific ligands, 2,7-tris-naphthalene (2,7-TrisNP) and tris-phenoxybenzene (TrisPOB), lead to TWJ stabilization, revealed by an increase in the melting temperature (Tm) by 13 or 26 °C, respectively. To gain insights into conformational changes in the gas phase, we employed cIMS and SID to analyze TWJs and their complexes with ligands. Analysis of IM arrival distributions suggested a single-step dissociation of TWJs and their intermediates for the three studied TWJ complexes. Upon ligand binding, a higher SID energy by 3 V (2,7-TrisNP) and 5 V (TrisPOB) was required to induce 50% dissociation of TWJ, compared to 38 V in the absence of ligands. Our results demonstrate the power of utilizing TC-nESI-MS in combination with cIMS and SID for thermodynamic characterization of TWJ complexes and investigation of ligand binding. These techniques are essential for the TWJ design and development as drug targets, aptamers, and structural units for functional biomaterials.

Differences Between Online Trial Participants Who Have Used Statutory Mental Health Services and Those Who Have Not: Analysis of Baseline Data From 2 Pragmatic Trials of a Digital Health Intervention.

BACKGROUND: Digital health interventions (DHIs) are an established element of mental health service provision internationally. Regulators have positioned the best practice standard of evidence as an interventional study with a comparator reflective of standard care, often operationalized as a pragmatic trial. DHIs can extend health provision to those not currently using mental health services. Hence, for external validity, trials might openly recruit a mixture of people who have used mental health services and people who have not. Prior research has demonstrated phenomenological differences in mental health experience between these groups. Some differences between service users and nonservice users might influence the change created by DHIs; hence, research should systematically examine these differences to inform intervention development and evaluation work. This paper analyzes baseline data collected in the NEON (Narrative Experiences Online; ie, for people with experience of psychosis) and NEON-O (NEON for other [eg, nonpsychosis] mental health problems) trials. These were pragmatic trials of a DHI that openly recruited people who had used specialist mental health services and those who had not. All participants were experiencing mental health distress. NEON Trial participants had experienced psychosis in the previous 5 years. OBJECTIVE: This study aims to identify differences in baseline sociodemographic and clinical characteristics associated with specialist mental health service use for NEON Trial and NEON-O Trial participants. METHODS: For both trials, hypothesis testing was used to compare baseline sociodemographic and clinical characteristics of participants in the intention-to-treat sample who had used specialist mental health services and those who had not. Bonferroni correction was applied to significance thresholds to account for multiple testing. RESULTS: Significant differences in characteristics were identified in both trials. Compared with nonservice users (124/739, 16.8%), NEON Trial specialist service users (609/739, 82.4%) were more likely to be female (P<.001), older (P<.001), and White British (P<.001), with lower quality of life (P<.001) and lower health status (P=.002). There were differences in geographical distribution (P<.001), employment (P<.001; more unemployment), current mental health problems (P<.001; more psychosis and personality disorders), and recovery status (P<.001; more recovered). Current service users were more likely to be experiencing psychosis than prior service users. Compared with nonservice users (399/1023, 39%), NEON-O Trial specialist service users (614/1023, 60.02%) had differences in employment (P<.001; more unemployment) and current mental health problems (P<.001; more personality disorders), with lower quality of life (P<.001), more distress (P<.001), less hope (P<.001), less empowerment (P<.001), less meaning in life (P<.001), and lower health status (P<.001). CONCLUSIONS: Mental health service use history was associated with numerous differences in baseline characteristics. Investigators should account for service use in work to develop and evaluate interventions for populations with mixed service use histories. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): RR2-10.1186/s13063-020-04428-6.

Prototyping of a lateral flow assay based on monoclonal antibodies for detection of Bothrops venoms.

BACKGROUND: Brazil is home to a multitude of venomous snakes; perhaps the most medically relevant of which belong to the Bothrops genus. Bothrops spp. are responsible for roughly 70% of all snakebites in Brazil, and envenomings caused by their bites can be treated with three types of antivenom: bothropic antivenom, bothro-lachetic antivenom, and bothro-crotalic antivenom. The choice to administer antivenom depends on the severity of the envenoming, while the choice of antivenom depends on availability and on how certain the treating physician is that the patient was bitten by a bothropic snake. The diagnosis of a bothropic envenoming can be made based on expert identification of the dead snake or a photo thereof or based on a syndromic approach wherein the clinician examines the patient for characteristic manifestations of envenoming. This approach can be very effective but requires staff that has been trained in clinical snakebite management, which, unfortunately, far from all relevant staff has. RESULTS: In this article, we describe a prototype of the first lateral flow assay (LFA) capable of detecting venoms from Brazilian Bothrops spp. The monoclonal antibodies for the assay were generated using hybridoma technology and screened in sandwich enzyme-linked immunosorbent assays (ELISAs) to identify Bothrops spp.-specific antibody sandwich pairs. The prototype LFA is able to detect venom from several Bothrops spp. The LFA has a limit of detection (LoD) of 9.5 ng/mL in urine, when read with a commercial reader, and a visual LoD of approximately 25 ng/mL. SIGNIFICANCE: The work presented here serves as a proof of concept for a genus-specific venom detection kit that could support physicians in diagnosing Bothrops envenomings. Although further optimisation and testing is needed before the LFA can find clinical use, such a device could aid in decentralising antivenoms in the Brazilian Amazon and help ensure optimal snakebite management for even more victims of this highly neglected disease.

Determining the gas-phase structures of α-helical peptides from shape, microsolvation, and intramolecular distance data.

Mass spectrometry is a powerful technique for the structural and functional characterization of biomolecules. However, it remains challenging to accurately gauge the gas-phase structure of biomolecular ions and assess to what extent native-like structures are maintained. Here we propose a synergistic approach which utilizes Förster resonance energy transfer and two types of ion mobility spectrometry (i.e., traveling wave and differential) to provide multiple constraints (i.e., shape and intramolecular distance) for structure-refinement of gas-phase ions. We add microsolvation calculations to assess the interaction sites and energies between the biomolecular ions and gaseous additives. This combined strategy is employed to distinguish conformers and understand the gas-phase structures of two isomeric α-helical peptides that might differ in helicity. Our work allows more stringent structural characterization of biologically relevant molecules (e.g., peptide drugs) and large biomolecular ions than using only a single structural methodology in the gas phase.

Continuous Electrospray Ionization Mass Spectrometry Assay for Measuring Phospholipase Activity against Liposomes.

Phospholipases have diverse roles in lipid and cell membrane biology. In animal venoms, they can have roles as neurotoxins or myotoxins that disrupt the integrity of cell membranes. In this work, we describe a temperature-controlled, continuous electrospray ionization mass spectrometry (ESI-MS) assay for measuring phospholipase A2 activity against liposomes. The enzyme used in this assay was paradoxin, which is a neurotoxic trimeric phospholipase A2 from inland taipan snake venom. Previously developed ESI-MS-based phospholipase assays have been discontinuous and analyzed hydrolysis of single lipid molecules by liquid chromatography ESI-MS. In this work, a continuous assay was developed against liposomes, a more complex substrate that more closely reflects the natural substrate for paradoxin. The assay confirmed the requirement for Ca2+ and allowed measurement of Michaelis-Menten-type parameters. The use of ESI-MS for lipid detection enabled nuanced insights into the effect of changing assay conditions not only on the enzyme but also on the liposome substrate. Changing the metal ion concentrations did not significantly change the liposomes but did affect enzymatic activity. Increasing temperature did not substantially affect the secondary structure of paradoxin but affected liposome size, resulting in increased enzymatic activity consistent with the disruption of the phosphatidylcholine membrane, increasing accessibility of sn-2 ester bonds. The continuous ESI-MS method described herein can be applied to other enzyme reactions, particularly those which utilize complex lipid substrates.

Assessing Diversity and Inclusivity is the Next Frontier in Mental Health Recovery Narrative Research and Practice.

Demand for digital health interventions is increasing in many countries. The use of recorded mental health recovery narratives in digital health interventions is becoming more widespread in clinical practice. Mental health recovery narratives are first-person lived experience accounts of recovery from mental health problems, including struggles and successes over time. Helpful impacts of recorded mental health recovery narratives include connectedness with the narrative and validation of experiences. Possible harms include feeling disconnected and excluded from others. Diverse narrative collections from many types of narrators and describing multiple ways to recover are important to maximize the opportunity for service users to benefit through connection and to minimize the likelihood of harm. Mental health clinicians need to know whether narrative collections are sufficiently diverse to recommend to service users. However, no method exists for assessing the diversity and inclusivity of existing or new narrative collections. We argue that assessing diversity and inclusivity is the next frontier in mental health recovery narrative research and practice. This is important, but methodologically and ethically complex. In this viewpoint, we propose and evaluate one diversity and two inclusivity assessment methods. The diversity assessment method involves use of the Simpson Diversity Index. The two inclusivity assessment methods are based on comparator demographic rates and arbitrary thresholds, respectively. These methods were applied to four narrative collections as a case study. Refinements are needed regarding a narrative assessment tool in terms of its practicality and cultural adaptation.

Discovery and optimization of a broadly-neutralizing human monoclonal antibody against long-chain α-neurotoxins from snakes.

Snakebite envenoming continues to claim many lives across the globe, necessitating the development of improved therapies. To this end, broadly-neutralizing human monoclonal antibodies may possess advantages over current plasma-derived antivenoms by offering superior safety and high neutralization capacity. Here, we report the establishment of a pipeline based on phage display technology for the discovery and optimization of high affinity broadly-neutralizing human monoclonal antibodies. This approach yielded a recombinant human antibody with superior broadly-neutralizing capacities in vitro and in vivo against different long-chain α-neurotoxins from elapid snakes. This antibody prevents lethality induced by Naja kaouthia whole venom at an unprecedented low molar ratio of one antibody per toxin and prolongs the survival of mice injected with Dendroaspis polylepis or Ophiophagus hannah whole venoms.

Advancing Cyclic Ion Mobility Mass Spectrometry Methods for Studying Biomolecules: Toward the Conformational Dynamics of Mega Dalton Protein Aggregates.

Native mass spectrometry is a powerful tool for the analysis of noncovalent complexes. When coupled with high-resolution ion mobility, this technique can be used to investigate the conformational changes induced in said complexes by different solution or gas-phase conditions. In this study, we describe how a new-generation high-resolution ion mobility instrument equipped with a cyclic ion mobility cell can be utilized for the analysis of large biomolecular systems, including temperature-induced protein aggregates of masses greater than 1.5 MDa, as well as a 63 kDa oligonucleotide complex. The effects of and the interplay between the voltages applied to the different components of the cyclic ion mobility spectrometry system on ion transmission and arrival time distribution were demonstrated using biomolecules covering the m/z range 2000-10,000. These data were used to establish a theoretical framework for achieving the best separation in the cyclic ion mobility system. Finally, the cyclic ion mobility mass spectrometer was coupled with a temperature-controlled electrospray ionization source to investigate high-mass protein aggregation. This analysis showed that it was possible to continuously monitor the change in abundance for several conformations of MDa aggregates with increasing temperature. This work significantly increases the range of biomolecules that can be analyzed by both cyclic ion mobility and temperature-controlled electrospray ionization mass spectrometry, providing new possibilities for high-resolution ion mobility analysis.

Structural Studies of a Stapled Peptide with Native Ion Mobility-Mass Spectrometry and Transition Metal Ion Förster Resonance Energy Transfer in the Gas Phase.

Native mass spectrometry has emerged as an important tool for gas-phase structural biology. However, the conformations that a biomolecular ion adopts in the gas phase can differ from those found in solution. Herein, we report a synergistic, native ion mobility-mass spectrometry (IM-MS) and transition metal ion Förster resonance energy transfer (tmFRET)-based approach to probe the gas-phase ion structures of a nonstapled peptide (nsp; Ac-CAARAAHAAAHARARA-NH2) and a stapled peptide (sp; Ac-CXARAXHAAAHARARA-NH2). The stapled peptide contains a single hydrocarbon chain connecting the peptide backbone in the i and i + 4 positions via a Grubbs ring-closure metathesis. Fluorescence lifetime measurements indicated that the Cu-bound complexes of carboxyrhodamine 6g (crh6g)-labeled stapled peptide (sp-crh6g) had a shorter donor-acceptor distance (rDA) than the labeled nonstapled peptide (nsp-crh6g). Experimental collision cross-section (CCS) values were then determined by native IM-MS, which could separate the conformations of Cu-bound complexes of nsp-crh6g and sp-crh6g. Finally, the experimental CCS (i.e., shape) and rDA (i.e., distance) values were used as constraints for computational studies, which unambiguously revealed how a staple reduces the elongation of the peptide ions in the gas phase. This study demonstrates the superiority of combining native IM-MS, tmFRET, and computational studies to investigate the structure of biomolecular ions.

Exploring Gas-Phase MS Methodologies for Structural Elucidation of Branched N-Glycan Isomers.

Structural isomers of N-glycans that are identical in mass and atomic composition provide a great challenge to conventional mass spectrometry (MS). This study employs additional dimensions of structural elucidation including ion mobility (IM) spectroscopy coupled to hydrogen/deuterium exchange (HDX) and electron capture dissociation (ECD) to characterize three main A2 N-glycans and their conformers. A series of IM-MS experiments were able to separate the low abundance N-glycans and their linkage-based isomers (α1-3 and α1-6 for A2G1). HDX-IM-MS data indicated the presence of multiple gas-phase structures for each N-glycan including the isomers of A2G1. Identification of A2G1 isomers by their collision cross section was complicated due to the preferential collapse of sugars in the gas phase, but it was possible by further ECD fragmentation. The cyclic IM-ECD approach was capable of assigning and identifying each isomer to its IM peak. Two unique cross-ring fragments were identified for each isomer: m/z = 624.21 for α1-6 and m/z = 462.16 for α1-3. Based on these key fragments, the first IM peak, indicating a more compact conformation, was assigned to α1-3 and the second IM peak, a more extended conformer, was assigned to α1-6.

Temperature-Controlled Electrospray Ionization: Recent Progress and Applications.

Native electrospray ionization (ESI) and nanoelectrospray ionization (nESI) allow researchers to analyze intact biomolecules and their complexes by mass spectrometry (MS). The data acquired using these soft ionization techniques provide a snapshot of a given biomolecules structure in solution. Over the last thirty years, several nESI and ESI sources capable of controlling spray solution temperature have been developed. These sources can be used to elucidate the thermodynamics of a given analyte, as well as provide structural information that cannot be readily obtained by other, more commonly used techniques. This review highlights how the field of temperature-controlled mass spectrometry has developed.

Recorded Mental Health Recovery Narratives as a Resource for People Affected by Mental Health Problems: Development of the Narrative Experiences Online (NEON) Intervention.

BACKGROUND: The internet enables sharing of narratives about health concerns on a substantial scale, and some digital health narratives have been integrated into digital health interventions. Narratives describing recovery from health problems are a focus of research, including those presented in recorded (eg, invariant) form. No clinical trial has been conducted on a web-based intervention providing access to a collection of Recorded Recovery Narratives (RRNs). OBJECTIVE: This study presents knowledge produced through the development of the Narrative Experiences Online (NEON) Intervention, a web-based intervention incorporating the algorithmic recommendation of RRNs. METHODS: Knowledge was gathered through knowledge integration (KI) activities. KI1 synthesized previous studies to produce the NEON Impact Model describing how accessing RRNs produces health-related outcomes. KI2 developed curation principles for the NEON Collection of RRNs through consultation with the NEON Lived Experience Advisory Panel and the curation of a preliminary collection. KI3 identified harm minimization strategies for the NEON Intervention through consultation with the NEON International Advisory Board and Lived Experience Advisory Panel. The NEON Intervention was finalized through 2 research studies (RS). In RS1, mental health service users (N=40) rated the immediate impact of randomly presented narratives to validate narrative feedback questions used to inform the recommendation algorithm. In RS2, mental health service users (n=25) were interviewed about their immediate response to a prototype of the NEON Intervention and trial procedures and then were interviewed again after 1 month of use. The usability and acceptability of the prototype and trial procedures were evaluated and refinements were made. RESULTS: KI1 produced the NEON Impact Model, which identifies moderators (recipient and context), mechanisms of connection (reflection, comparison, learning, and empathy), processes (identification of change from narrative structure or content and internalization of observed change), and outcomes (helpful and unhelpful). KI2 identified 22 curation principles, including a mission to build a large, heterogeneous collection to maximize opportunities for connection. KI3 identified seven harm minimization strategies, including content warnings, proactive and reactive blocking of narratives, and providing resources for the self-management of emotional distress. RS1 found variation in the impact of narratives on different participants, indicating that participant-level feedback on individual narratives is needed to inform a recommender system. The order of presentation did not predict narrative feedback. RS2 identified amendments to web-based trial procedures and the NEON Intervention. Participants accessed some narratives multiple times, use reduced over the 4-week period, and narrative feedback was provided for 31.8% (105/330) of narrative accesses. CONCLUSIONS: RRNs can be integrated into web-based interventions. Evaluating the NEON Intervention in a clinical trial is feasible. The mixed methods design for developing the NEON Intervention can guide its extension to other clinical populations, the design of other web-based mental health interventions, and the development of narrative-based interventions in mental health.

Trajectory Taken by Dimeric Cu/Zn Superoxide Dismutase through the Protein Unfolding and Dissociation Landscape Is Modulated by Salt Bridge Formation.

Native mass spectrometry (MS) is a powerful means for studying macromolecular protein assemblies, including accessing activated states. However, much remains to be understood about what governs which regions of the protein (un)folding funnel, which can be explored by activation of protein ions in a vacuum. Here, we examine the trajectory that Cu/Zn superoxide dismutase (SOD1) dimers take over the unfolding and dissociation free energy landscape in a vacuum. We examined wild-type SOD1 and six disease-related point mutants by using tandem MS and ion-mobility MS as a function of collisional activation. For six of the seven SOD1 variants, increasing activation prompted dimers to transition through two unfolding events and dissociate symmetrically into monomers with (as near as possible) equal charges. The exception was G37R, which proceeded only through the first unfolding transition and displayed a much higher abundance of asymmetric products. Supported by the observation that ejected asymmetric G37R monomers were more compact than symmetric G37R ones, we localized this effect to the formation of a gas-phase salt bridge in the first activated conformation. To examine the data quantitatively, we applied Arrhenius-type analysis to estimate the barriers on the corresponding free energy landscape. This reveals a heightening of the barrier to unfolding in G37R by >5 kJ/mol-1 over the other variants, consistent with expectations for the strength of a salt bridge. Our work demonstrates weaknesses in the simple general framework for understanding protein complex dissociation in a vacuum and highlights the importance of individual residues, their local environment, and specific interactions in governing product formation.

Fluoroscopically guided caudal epidural steroid injections for axial low back pain associated with central disc protrusions: a prospective outcome study.

PURPOSE: To determine if axial low back pain (LBP) associated with central disc protrusions can be improved by caudal epidural steroid injections (ESIs). METHODS: Adults with chronic (> 3 months) moderate-to-severe axial LBP with L4-5 and/or L5-S1 central disc protrusions were enrolled in this prospective study. Participants underwent caudal ESIs under standard-of-care practice. The numerical rating scale (NRS) pain score, modified North American Spine Society satisfaction, and Roland Morris Disability Questionnaire (RMDQ) were collected at one week, one month, three months, six months, and one year post-injection. Pre-injection magnetic resonance images were assessed by a musculoskeletal radiologist. RESULTS: Sixty-eight participants (42 males, 26 females) were analyzed. There were statistically significant improvements in all outcome measures at all follow-up time points, with the exception of NRS best pain at six months. Clinically significant improvements in outcomes were observed at various time points: at three months and one year for current pain; at one week, one month, three months, six months, and one year for worst pain; and at one month and one year for RMDQ. The proportion of satisfied participants ranged from 57 to 69% throughout the study. No adverse events were observed. CONCLUSIONS: This study demonstrated significant improvements in pain and function following caudal ESIs in a cohort of axial LBP with associated central disc protrusions. Further studies, including the use of randomized controlled trials, are needed to determine the ideal subset of candidates for this treatment and to explore additional applications that caudal ESIs may have for chronic LBP.

Correlation of Measurements of the Prearthritic Hip Between Plain Radiography and Computed Tomography.

BACKGROUND: Previous studies have compared radiographic and computed tomography (CT) imaging for the evaluation of prearthritic hip pain. However, the intermodality, interrater, and intrarater consistencies of those parameters have not been investigated. OBJECTIVE: To determine whether radiographs with an anteroposterior pelvis view and 45°-Dunn lateral view reliably correlate with CT in the context of lateral center edge (LCE), Tonnis, alpha, and beta angle measurements for femoroacetabular impingement or hip dysplasia diagnosis. DESIGN: Retrospective study. SETTING: Academic orthopedic institution. PATIENTS: Fifty consecutive participants with hip pain in the institutional hip registry with radiographs and CT imaging on file were evaluated between 2013 and 2014. MATERIALS AND METHODS: Radiologic data (50 CTs and 50 radiographs) were evaluated by 3 physicians. LCE, Tonnis, alpha, and beta angles were measured on radiographs and CTs in 2 rounds of readings. In round 1, the center of rotation on CT imaging was standardized by 1 rater. In round 2, individual raters chose CT images using a quadrant method, and reproducibility was assessed. Reliability statistics were operationalized with intraclass correlation coefficients (ICCs). MAIN OUTCOME MEASUREMENTS: Intermodality, intrarater, and interrater reliability of CT vs radiographic measurements. RESULTS: The intermodality reliability for all raters was excellent (ICC [95% CI]: 0.84 [0.76-0.90] to 0.97 [0.96-0.98]). Intrarater reliability for both modalities showed excellent reliability (ICC = 0.75-0.96). Interrater reliability of CT measures of LCE, Tonnis, and alpha angles demonstrated excellent agreement (ICC ≥ 0.88). Beta angle measures demonstrated good agreement (ICC [95% CI] = 0.68 [0.49-0.81]). Interrater reliability of radiographic measures showed excellent agreement (ICC = 0.82-0.94). CONCLUSION: Equivalent angle measurement readings on CT and radiographs were consistent among physicians. CT measurements correlated well with radiographic measurements. This suggests that if a standardized procedure is used to find the center of the femoral head, a positive correlation among LCE, alpha, beta, and Tonnis angles measured on CT can be obtained between multiple readers. LEVEL OF EVIDENCE: III.

Conditions for Analysis of Native Protein Structures Using Uniform Field Drift Tube Ion Mobility Mass Spectrometry and Characterization of Stable Calibrants for TWIM-MS.

Determination of collisional cross sections (CCS) by travelling wave ion mobility mass spectrometry (TWIM-MS) requires calibration against standards for which the CCS has been measured previously by drift tube ion mobility mass spectrometry (DTIM-MS). The different extents of collisional activation in TWIM-MS and DTIM-MS can give rise to discrepancies in the CCS of calibrants across the two platforms. Furthermore, the conditions required to ionize and transmit large, folded proteins and assemblies may variably affect the structure of the calibrants and analytes. Stable hetero-oligomeric phospholipase A2 (PDx) and its subunits were characterized as calibrants for TWIM-MS. Conditions for acquisition of native-like TWIM (Synapt G1 HDMS) and DTIM (Agilent 6560 IM-Q-TOF) mass spectra were optimized to ensure the spectra exhibited similar charge state distributions. CCS measurements (DTIM-MS) for ubiquitin, cytochrome c, holo-myoglobin, serum albumin and glutamate dehydrogenase were in good agreement with other recent results determined using this and other DTIM-MS instruments. PDx and its ß and γ subunits were stable across a wide range of cone and trap voltages in TWIM-MS and were stable in the presence of organic solvents. The CCS of PDx and its subunits were determined by DTIM-MS and were used as calibrants in determination of CCS of native-like cytochrome c, holo-myoglobin, carbonic anhydrase, serum albumin and haemoglobin in TWIM-MS. The CCS values were in good agreement with those measured by DTIM-MS where available. These experiments demonstrate conditions for analysis of native-like proteins using a commercially available DTIM-MS instrument, characterize robust calibrants for TWIM-MS, and present CCS values determined by DTIM-MS and TWIM-MS for native proteins to add to the current literature database. Graphical Abstract ᅟ.