An efficient pyrrolysyl-tRNA synthetase for economical production of MeHis-containing enzymes.

Genetic code expansion has emerged as a powerful tool in enzyme design and engineering, providing new insights into sophisticated catalytic mechanisms and enabling the development of enzymes with new catalytic functions. In this regard, the non-canonical histidine analogue Nδ-methylhistidine (MeHis) has proven especially versatile due to its ability to serve as a metal coordinating ligand or a catalytic nucleophile with a similar mode of reactivity to small molecule catalysts such as 4-dimethylaminopyridine (DMAP). Here we report the development of a highly efficient aminoacyl tRNA synthetase (G1PylRSMIFAF) for encoding MeHis into proteins, by transplanting five known active site mutations from Methanomethylophilus alvus (MaPylRS) into the single domain PylRS from Methanogenic archaeon ISO4-G1. In contrast to the high concentrations of MeHis (5-10 mM) needed with the Ma system, G1PylRSMIFAF can operate efficiently using MeHis concentrations of ∼0.1 mM, allowing more economical production of a range of MeHis-containing enzymes in high titres. Interestingly G1PylRSMIFAF is also a 'polyspecific' aminoacyl tRNA synthetase (aaRS), enabling incorporation of five different non-canonical amino acids (ncAAs) including 3-pyridylalanine and 2-fluorophenylalanine. This study provides an important step towards scalable production of engineered enzymes that contain non-canonical amino acids such as MeHis as key catalytic elements.

Expanding Orbitrap Collision Cross-Section Measurements to Native Protein Applications Through Kinetic Energy and Signal Decay Analysis.

The measurement of collision cross sections (CCS, σ) offers supplemental information about sizes and conformations of ions beyond mass analysis alone. We have previously shown that CCSs can be determined directly from the time-domain transient decay of ions in an Orbitrap mass analyzer as ions oscillate around the central electrode and collide with neutral gas, thus removing them from the ion packet. Herein, we develop the modified hard collision model, thus deviating from the prior FT-MS hard sphere model, to determine CCSs as a function of center-of-mass collision energy in the Orbitrap analyzer. With this model, we aim to increase the upper mass limit of CCS measurement for native-like proteins, characterized by low charge states and presumed to be in more compact conformations. We also combine CCS measurements with collision induced unfolding and tandem mass spectrometry experiments to monitor protein unfolding and disassembly of protein complexes and measure CCSs of ejected monomers from protein complexes.

Online Buffer Exchange Enables Automated Membrane Protein Analysis by Native Mass Spectrometry.

Membrane proteins represent the majority of clinical drug targets and are actively involved in a range of cellular processes. However, the complexity of membrane mimetics for membrane protein solubilization poses challenges for native mass spectrometry (MS) analyses. The most common approach for native MS analyses of membrane proteins remains offline buffer exchange into native MS-compatible buffers prior to manual sample loading into static nano-ESI emitters. This laborious process requires relatively high sample consumption and optimization for the individual proteins. Here, we developed online buffer exchange coupled to native mass spectrometry (OBE-nMS) for analyzing membrane proteins in different membrane mimetics, including detergent micelles and nanodiscs. Detergent screening for OBE-nMS reveals that mobile phases containing ammonium acetate with lauryl-dimethylamine oxide are most universal for characterizing both bacterial and mammalian membrane proteins in detergent. Membrane proteins in nanodiscs simply require ammonium acetate as the mobile phase. To preserve the intact nanodiscs, a novel switching electrospray approach was used to capture the high-flow separation on the column with a low-flow injection to MS. Rapid OBE-nMS completes each membrane protein measurement within minutes and thus enables higher-throughput assessment of membrane protein integrity prior to its structural elucidation.

Accelerometer-Measured Physical Activity Data Sets (Global Physical Activity Data Set Catalogue) That Include Markers of Cardiometabolic Health: Systematic Scoping Review.

BACKGROUND: Cardiovascular disease accounts for 17.9 million deaths globally each year. Many research study data sets have been collected to answer questions regarding the relationship between cardiometabolic health and accelerometer-measured physical activity. This scoping review aimed to map the available data sets that have collected accelerometer-measured physical activity and cardiometabolic health markers. These data were then used to inform the development of a publicly available resource, the Global Physical Activity Data set (GPAD) catalogue. OBJECTIVE: This review aimed to systematically identify data sets that have measured physical activity using accelerometers and cardiometabolic health markers using either an observational or interventional study design. METHODS: Databases, trial registries, and gray literature (inception until February 2021; updated search from February 2021 to September 2022) were systematically searched to identify studies that analyzed data sets of physical activity and cardiometabolic health outcomes. To be eligible for inclusion, data sets must have measured physical activity using an accelerometric device in adults aged ≥18 years; a sample size >400 participants (unless recruited participants in a low- and middle-income country where a sample size threshold was reduced to 100); used an observational, longitudinal, or trial-based study design; and collected at least 1 cardiometabolic health marker (unless only body mass was measured). Two reviewers screened the search results to identify eligible studies, and from these, the unique names of each data set were recorded, and characteristics about each data set were extracted from several sources. RESULTS: A total of 17,391 study reports were identified, and after screening, 319 were eligible, with 122 unique data sets in these study reports meeting the review inclusion criteria. Data sets were found in 49 countries across 5 continents, with the most developed in Europe (n=53) and the least in Africa and Oceania (n=4 and n=3, respectively). The most common accelerometric brand and device wear location was Actigraph and the waist, respectively. Height and body mass were the most frequently measured cardiometabolic health markers in the data sets (119/122, 97.5% data sets), followed by blood pressure (82/122, 67.2% data sets). The number of participants in the included data sets ranged from 103,712 to 120. Once the review processes had been completed, the GPAD catalogue was developed to house all the identified data sets. CONCLUSIONS: This review identified and mapped the contents of data sets from around the world that have collected potentially harmonizable accelerometer-measured physical activity and cardiometabolic health markers. The GPAD catalogue is a web-based open-source resource developed from the results of this review, which aims to facilitate the harmonization of data sets to produce evidence that will reduce the burden of disease from physical inactivity.

Safely Reducing Unnecessary Radiographs in Suspected Pediatric Musculoskeletal Injuries: A Multidisciplinary Developed Algorithm.

BACKGROUND: While radiographs are a critical component of diagnosing musculoskeletal (MSK) injuries, they are associated with radiation exposure, patient discomfort, and financial costs. Our study initiative was to develop a system to diagnose pediatric MSK injuries efficiently while minimizing unnecessary radiographs. METHODS: This was a quality improvement trial performed prospectively at a single level one trauma center. A multidisciplinary team with leaders from pediatric orthopedics, trauma surgery, emergency medicine, and radiology created an algorithm delineating which x-rays should be obtained for pediatric patients presenting with MSK injuries. The intervention was performed in the following 3 stages: stage 1: retrospective validation of the algorithm, stage 2: implementation of the algorithm, and stage 3: sustainability evaluation. Outcomes measured included number of extra radiographs per pediatric patient and any missed injuries. RESULTS: In stage 1, 295 patients presented to the pediatric emergency department with MSK injuries. A total of 2148 radiographs were obtained, with 801 not indicated per the protocol, for an average of 2.75 unnecessary radiographs per patient. No injuries would have been missed using the protocol. In stage 2, 472 patients had 2393 radiographs with 339 not indicated per protocol, averaging 0.72 unnecessary radiographs per patient, a significant reduction from stage 1 ( P < 0.001). There were no missed injuries identified on follow-up. In stage 3, improvement was sustained for the subsequent 8 months with an average of 0.34 unnecessary radiographs per patient ( P < 0.05). CONCLUSIONS: Sustained reduction of unnecessary radiation to pediatric patients with suspected MSK injuries was accomplished through the development and implementation of a safe and effective imaging algorithm. The multidisciplinary approach, widespread education of pediatric providers, and standardized order sets improved buy-in and is generalizable to other institutions.Level of Evidence: III.

Nanohydrophobic Interaction Chromatography Coupled to Ultraviolet Photodissociation Mass Spectrometry for the Analysis of Intact Proteins in Low Charge States.

The direct correlation between proteoforms and biological phenotype necessitates the exploration of mass spectrometry (MS)-based methods more suitable for proteoform detection and characterization. Here, we couple nano-hydrophobic interaction chromatography (nano-HIC) to ultraviolet photodissociation MS (UVPD-MS) for separation and characterization of intact proteins and proteoforms. High linearity, sensitivity, and sequence coverage are obtained with this method for a variety of proteins. Investigation of collisional cross sections of intact proteins during nano-HIC indicates semifolded conformations in low charge states, enabling a different dimension of separation in comparison to traditional, fully denaturing reversed-phase separations. This method is demonstrated for a mixture of intact proteins from Escherichia coli ribosomes; high sequence coverage is obtained for a variety of modified and unmodified proteoforms.

Enhancing the Signal-to-Noise of Diagnostic Fragment Ions of Unsaturated Glycerophospholipids via Precursor Exclusion Ultraviolet Photodissociation Mass Spectrometry (PEx-UVPD-MS).

Understanding and elucidating the diverse structures and functions of lipids has motivated the development of many innovative tandem mass spectrometry (MS/MS) strategies. Higher-energy activation methods, such as ultraviolet photodissociation (UVPD), generate unique fragment ions from glycerophospholipids that can be used to perform in-depth structural analysis and facilitate the deconvolution of isomeric lipid structures in complex samples. Although detailed characterization is central to the correlation of lipid structure to biological function, it is often impeded by the lack of sufficient instrument sensitivity for highly bioactive but low-abundance phospholipids. Here, we present precursor exclusion (PEx) UVPD, a simple yet powerful technique to enhance the signal-to-noise (S/N) of informative low-abundance fragment ions produced from UVPD of glycerophospholipids. Through the exclusion of the large population of undissociated precursor ions with an MS3 strategy, the S/N of diagnostic fragment ions from PC 18:0/18:2(9Z, 12Z) increased up to an average of 13x for PEx-UVPD compared to UVPD alone. These enhancements were extended to complex mixtures of lipids from bovine liver extract to confidently identify 35 unique structures using liquid chromatography PEx-UVPD. This methodology has the potential to advance lipidomics research by offering deeper structure elucidation and confident identification of biologically active lipids.

Separation and Collision Cross Section Measurements of Protein Complexes Afforded by a Modular Drift Tube Coupled to an Orbitrap Mass Spectrometer.

New developments in analytical technologies and biophysical methods have advanced the characterization of increasingly complex biomolecular assemblies using native mass spectrometry (MS). Ion mobility methods, in particular, have enabled a new dimension of structural information and analysis of proteins, allowing separation of conformations and providing size and shape insights based on collision cross sections (CCSs). Based on the concepts of absorption-mode Fourier transform (aFT) multiplexing ion mobility spectrometry (IMS), here, a modular drift tube design proves capable of separating native-like proteins up to 148 kDa with resolution up to 45. Coupled with high-resolution Orbitrap MS, binding of small ligands and cofactors can be resolved in the mass domain and correlated to changes in structural heterogeneity observed in the ion-neutral CCS distributions. We also demonstrate the ability to rapidly determine accurate CCSs for proteins with 1-min aFT-IMS-MS sweeps without the need for calibrants or correction factors.

Advancing Orbitrap Measurements of Collision Cross Sections to Multiple Species for Broad Applications.

Measurement of collision cross section (CCS), a parameter reflecting an ion's size and shape, alongside high-resolution mass analysis extends the depth of molecular analysis by providing structural information beyond molecular mass alone. Although these measurements are most commonly undertaken using a dedicated ion mobility cell coupled to a mass spectrometer, alternative methods have emerged to extract CCSs directly by analysis of the decay rates of either time-domain transient signals or the FWHM of frequency domain peaks in FT mass analyzers. This information is also accessible from FTMS mass spectra obtained in commonly used workflows directly without the explicit access to transient or complex Fourier spectra. Previously, these experiments required isolation of individual charge states of ions prior to CCS analysis, limiting throughput. Here we advance Orbitrap CCS measurements to more users and applications by determining CCSs from commonly available mass spectra files as well as estimating CCS for multiple charge states simultaneously and showcase these methods by the measurement of CCSs of fragment ions produced from collisional activation of proteins.

Enhanced Ion Mobility Separation and Characterization of Isomeric Phosphatidylcholines Using Absorption Mode Fourier Transform Multiplexing and Ultraviolet Photodissociation Mass Spectrometry.

The structural diversity of phospholipids plays a critical role in cellular membrane dynamics, energy storage, and cellular signaling. Despite its importance, the extent of this diversity has only recently come into focus, largely owing to advances in separation science and mass spectrometry methodology and instrumentation. Characterization of glycerophospholipid (GP) isomers differing only in their acyl chain configurations and locations of carbon-carbon double bonds (C═C) remains challenging due to the need for both effective separation of isomers and advanced tandem mass spectrometry (MS/MS) technologies capable of double-bond localization. Drift tube ion mobility spectrometry (DTIMS) coupled with MS can provide both fast separation and accurate determination of collision cross section (CCS) of molecules but typically lacks the resolving power needed to separate phospholipid isomers. Ultraviolet photodissociation (UVPD) can provide unambiguous double-bond localization but is challenging to implement on the timescales of modern commercial drift tube time-of-flight mass spectrometers. Here, we present a novel method for coupling DTIMS with a UVPD-enabled Orbitrap mass spectrometer using absorption mode Fourier transform multiplexing that affords simultaneous localization of double bonds and accurate CCS measurements even when isomers cannot be fully resolved in the mobility dimension. This method is demonstrated on two- and three-component mixtures and shown to provide CCS measurements that differ from those obtained by individual analysis of each component by less than 1%.

Effectiveness of interventions to increase device-measured physical activity in pregnant women: systematic review and meta-analysis of randomised controlled trials.

BACKGROUND: Interventions that provide pregnant women with opportunities to access and participate in physical activity have been shown to be beneficial to their health. Much of this evidence however has been based on self-reported physical activity data, which may be prone to inflated effects due to recall bias and social desirability bias. No previous synthesis of randomised controlled trials has assessed the effectiveness of these interventions using only device measured data, to assess their health benefits more accurately in pregnant women. This systematic review and meta-analysis aimed to address this evidence gap. DATA SOURCES: Cochrane Central Register of Controlled Trials, Medline, SportDiscus, APA PsycINFO, Embase and Web of Science databases were queried from inception up to December 2, 2021. An updated search of PubMed was conducted on May 16, 2022. STUDY ELIGIBILITY CRITERIA: Randomised controlled trials that recruited pregnant women, participating in any physical activity intervention (excluding interventions aimed entirely at body conditioning), compared with standard antenatal care (comparators), using device-measured total physical activity as an outcome were eligible for inclusion. METHODS: 3144 titles and abstracts were screened for eligibility, and 18 met the inclusion criteria. Data were analysed using random effect models, (standardised mean difference and mean difference), using data from baseline to last available follow-up (primary end point), and until between 24 to 30 weeks gestation. Gestational weight gain was also assessed at these timepoints in the included trials. RESULTS: No significant differences between the groups were found for total physical activity at last available follow-up or 24 to 30 weeks gestation (95% CI 0.03 to 0.27, p = 0.10: 95% CI -0.05 to 0.33, p = 0.15) respectively. On average, pregnant women randomised to a physical activity intervention completed 435 and 449 more steps per day than comparators at last available follow-up and at 24 to 30 weeks gestation (95% CI -0.5-870.6, p = 0.05: 95% CI 5.5-892.7, p = 0.05) respectively. Intervention participants also gained 0.69 kg less (95% CI -1.30 to -0.08, p = 0.03) weight than comparators. CONCLUSION: Based on device-measured data, interventions to promote physical activity during pregnancy have small but important effects on increasing physical activity and managing excessive gestational weight gain.

Using Skeletal Maturity in Pediatric Orthopaedics: A Primer.

This article provides researchers with the background and guidance necessary to practically incorporate skeletal maturity estimation into any study of adolescents with imaging of the shoulder, elbow, hand, hip, knee, or foot. It also provides clinicians with a comprehensive, concise synopsis of systems that can be used to estimate skeletal maturity in clinical practice. In the article, we provide a relatively brief overview of each currently available skeletal maturity system that has been validated on a longitudinal dataset. The supplementary files include 2 PowerPoint files for each skeletal maturity system. The first PowerPoint file offers examples and instructions for using each radiographic system. The second PowerPoint file includes 20 graded radiographs that can be used for reliability analyses in the research setting. We have also developed a free mobile application available on the iOS and Android platforms named "What's the Skeletal Maturity?" that allows clinicians to rapidly estimate skeletal maturity on any patient using any commonly obtained orthopaedic radiograph.

Absorption Mode Fourier Transform Ion Mobility Mass Spectrometry Multiplexing Combined with Half-Window Apodization Windows Improves Resolution and Shortens Acquisition Times.

Fourier transform multiplexing enables the coupling of drift tube ion mobility to a wide array of mass spectrometers with improved ion utilization and duty cycles compared to dual-gate signal averaging methods. Traditionally, the data generated by this method is presented in the magnitude mode, but significant improvements in resolution and the signal-to-noise ratio (SNR) are expected if the data can be phase corrected and presented in the absorption mode. A method to simply and reliably determine and correct phase shifts in Fourier transform ion mobility mass spectrometry data using information readily available to any user is presented and evaluated for both small molecule and intact protein analyses with no modification to instrument hardware or experimental procedures. Additionally, the effects of apodization and zero padding are evaluated for both processing methods, and a strategy to use these techniques to reduce acquisition times is presented and evaluated. Resolution is improved by an average factor of 1.6, the SNR is improved by an average factor of 1.2, and acquisition times are reduced by up to 80% through the application of absorption mode processing combined with apodization and zero padding.

'Snacktivity™' to increase physical activity: Time to try something different?

Evidence demonstrates that participation in regular physical activity (PA) reduces the risk of morbidity and mortality. However, current PA guidelines are focused on weekly accumulation of 150 min of moderate intensity PA as a threshold. Although recent developments of this guidance have discussed the merits of short bouts of physical activity, guidance that sets large behavioural goals for PA has not been successful in supporting the public to become sufficiently physically active and a 'one-size fits all' approach to PA guidelines may not be optimal. A complementary 'whole day' approach to PA promotion (i.e. incorporating PA throughout the day) that could motivate the population to be more physically active, is a concept we have called 'Snacktivity™'. The Snacktivity™ approach promotes small or 'bite' size bouts (e.g. 2-5 min) of PA accumulated throughout the whole day. Snacktivity™ is consistent with the small change approach which suggest that behaviour change and habit formation are best achieved through gradual building of task self-efficacy, celebrating small successes. Snacktivity™ also offers opportunities to "piggyback" on to existing behaviours/habits, using them as prompts for Snacktivity™. Moreover, small behaviour changes are easier to initiate and maintain than larger ones. A plethora of evidence supports the hypothesis that Snacktivity may be a more acceptable and effective way to help the public reach, or exceed current PA guidelines. This paper outlines the evidence to support the Snacktivity™ approach and the mechanisms by which it may increase population levels of physical activity. Future research directions for Snacktivity™ are also outlined.

Systematic Isolation of Key Parameters for Estimating Skeletal Maturity on AP Hip Radiographs.

BACKGROUND: The ability to estimate skeletal maturity using a hip radiograph does not yet exist, but may have utility in the treatment of scoliosis, slipped capital femoral epiphysis, and lower limb deformity. We sought to develop a fast, accurate, and reproducible method. METHODS: Fourteen hip radiologic parameters were evaluated on serial anteroposterior hip radiographs from 3 years before to 2 years after the skeletal age associated with 90% of final height, a validated skeletal maturity definition which correlates with the timing of peak height velocity. The Greulich and Pyle (GP) left hand bone age was obtained for comparison. Stepwise linear regression and generalized estimating equation analyses were used to isolate key hip and demographic parameters, creating the "optimized Oxford" skeletal maturity system. The accuracy of the optimized Oxford system in predicting years from 90% of final height was evaluated and compared with systems of demographics only, the modified Oxford, demographics+modified Oxford, and demographics+GP. RESULTS: A total of 284 hip radiographs from 41 girls (range: 7 to 15 y) and 38 boys (range: 9 to 17 y) were included. Following multivariate analyses, 5 of the original 14 hip radiographic parameters remained significant. The predictions made by the optimized Oxford model had greater accuracy and fewer outlier predictions (predictions >1 y off from actual years from 90% of final height) than the demographics only and modified Oxford only models (P<0.05 for all). The optimized Oxford model had greater prediction accuracy than the demographics+modified Oxford model, but similar rates of outlier predictions (P=0.903). No differences in mean prediction accuracy or rate of outlier predictions were observed between the optimized Oxford and the demographics+GP model (P>0.05). CONCLUSION: High precision in skeletal maturity estimation can be achieved by using chronological age, sex, and 5 hip radiographic parameters. CLINICAL RELEVANCE: We have developed a skeletal maturity system that utilizes anteroposterior hip radiographs and performs as accurately as GP.

When Is a Growth-friendly Strategy Warranted? A Matched Comparison of Growing Rods Versus Primary Posterior Spinal Fusion in Juveniles With Early-onset Scoliosis.

BACKGROUND: In 7 to 11-year-old juveniles with severe early-onset scoliosis (EOS) the optimal surgical option remains uncertain. This study compares growing rods (GRs) followed by definitive posterior spinal fusion (PSF) versus primary PSF in this population. We hypothesized that the thoracic height afforded by GRs would be offset by increased rigidity, more complications, and more operations. METHODS: This retrospective comparative study included EOS patients aged 7.0 to 11.9 years at index surgery treated with GR→PSF or primary PSF during 2013 to 2020. Primary outcomes were thoracic height gain (ΔT1-12H), major curve, complications, and total operations. Primary PSFs were matched with replacement 1-to-n to GR→PSFs by age at index, etiology, and major curve. RESULTS: Twenty-eight GR→PSFs met criteria: 19 magnetically controlled GRs and 9 traditional GRs. Three magnetically controlled GRs were definitively explanted without PSF due to complications. The remaining 25 GR→PSFs were matched to 17 primary PSFs with 100% etiology match, mean Δ major curve 1 degree, and mean Δ age at index 0.5 years (PSFs older). Median ΔT1-12H pre-GR to post-PSF was 4.7 cm with median deformity correction of 37%. Median ΔT1-12H among primary PSFs was 1.9 cm with median deformity correction of 62%. GR→PSFs had mean 1.8 complications and 3.4 operations. Primary PSFs had mean 0.5 complications and 1.3 operations. Matched analysis showed adjusted mean differences of 2.3 cm greater ΔT1-12H among GR→PSFs than their matched primary PSFs, with 25% less overall coronal deformity correction, 1.2 additional complications, and 2.2 additional operations per patient. CONCLUSIONS: In juveniles aged 7 to 11 with EOS, on average GRs afford 2 cm of thoracic height over primary PSF at the cost of poorer deformity correction and additional complications and operations. Primary PSF affords an average of 2 cm of thoracic height gain; if an additional 2 cm will be impactful then GRs should be considered. However, in most juveniles the height gained may not warrant the iatrogenic stiffness, complications, and additional operations. Surgeons and families should weigh these benefits and harms when choosing a treatment plan. LEVEL OF EVIDENCE: Level III-retrospective comparative study.

Enhanced Sequence Coverage of Large Proteins by Combining Ultraviolet Photodissociation with Proton Transfer Reactions.

Ultraviolet photodissociation (UVPD) produces rich and informative fragmentation of intact protein ions, but in the case of high mass proteins (>30 kDa) the spectra are congested with overlapping isotope patterns of highly charged fragment ions. In the most congested regions, many fragments cannot be confidently identified even when high-resolution mass analyzers and modern deconvolution algorithms are used. Gas-phase ion-ion proton transfer reactions (PTR), which reduce the charge states of highly charged ions, can be used to alleviate this congestion and facilitate the identification of additional fragment ions when performed following UVPD. We have developed protocols for sequentially performing PTR on multiple populations of ions generated by UVPD in a way that can be tailored to balance the depth of characterization with speed and throughput. The improvements in sequence coverage and fragment identifications are demonstrated for four proteins ranging in size from 29 to 56 kDa. Sequence coverages up to 80% were achieved for carbonic anhydrase (29 kDa), 50% for aldolase (39 kDa), 46% for enolase (46 kDa), and 27% for glutamate dehydrogenase (56 kDa), and up to 74% sequence coverage was obtained for 25 kDa antibody drug conjugate subunits in online LC-MS experiments.

Effect of reduced photon count levels and choice of normal data on semi-automated image assessment in cardiac SPECT.

BACKGROUND: The SMARTZOOM multifocal collimator from Siemens Healthcare was developed to improve the γ-photon sensitivity in myocardial perfusion imaging without truncating the field of view. As part of the IQ-SPECT package, it may be used to reduce radiopharmaceutical dose to patients, as well as acquisition time. The aim of this study was twofold: (1) to evaluate the influence of dose reduction in semi-automated MPI scoring, with focus on different strategies for the choice of normal data (count-matched, full-count), and (2) to evaluate the effect of dose reduction afforded by Siemens' IQ-SPECT package. METHODS: 50 patients underwent Tc-99m-sestamibi one-day stress/rest SPECT/CT. Multiple levels of count reduction were generated using binomial thinning. Using Corridor 4DM, summed stress score (SSS) was calculated using either count-matched or full-count normal data. Studies were classified as low-risk (SSS < 4) or intermediate/high-risk (SSS ≥ 4). RESULTS: Count reduction using count-matched normal data increases false-normal rate and decreases sensitivity. With full-count normal data, count reduction increases false-hypoperfusion rate, leading to decreased specificity. Altogether, rate of reclassification was significant at roughly 67% dose and below. CONCLUSION: Significant bias results from count level of normal data relative to actual patient data. Compared to standard LEHR, IQ-SPECT should allow for significant dose reduction.

Characterizing Use of Growth-friendly Implants for Early-onset Scoliosis: A 10-Year Update.

BACKGROUND: Growth-friendly treatment of early-onset scoliosis (EOS) has changed with the development and evolution of multiple devices. This study was designed to characterize changes in the use of growth-friendly implants for EOS from 2007 to 2017. METHODS: We queried the Pediatric Spine Study Group database for patients who underwent index surgery with growth-friendly implants from July 2007 to June 2017. In 1298 patients, we assessed causes of EOS; preoperative curve magnitude; age at first surgery; patient sex; construct type; lengthening interval; incidence of "final" fusion for definitive treatment; and age at definitive treatment. α=0.05. RESULTS: From 2007 to 2017, the annual proportion of patients with idiopathic EOS increased from 12% to 33% (R=0.58, P=0.006). Neuromuscular EOS was the most common type at all time points (range, 33% to 44%). By year, mean preoperative curve magnitude ranged from 67 to 77 degrees, with no significant temporal changes. Mean (±SD) age at first surgery increased from 6.1±2.9 years in 2007 to 7.8±2.5 years in 2017 (R=0.78, P<0.001). As a proportion of new implants, magnetically controlled growing rods increased from <5% during the first 2 years to 83% in the last 2 years of the study. Vertically expandable prosthetic titanium ribs decreased from a peak of 48% to 6%; growth-guidance devices decreased from 10% to 3%. No change was seen in mean surgical lengthening intervals (range, 6 to 9 mo) for the 614 patients with recorded lengthenings. Final fusion was performed in 88% of patients who had undergone definitive treatment, occurring at a mean age of 13.4±2.4 years. CONCLUSIONS: From 2007 to 2017, neuromuscular EOS was the most common diagnosis for patients treated with growth-friendly implants. Patient age at first surgery and the use of magnetically controlled growing rods increased during this time. Preoperative curve magnitude, traditional growing rod lengthening intervals, and rates of final fusion did not change. LEVEL OF EVIDENCE: Level II.

Pharmacologic Treatments for Coronavirus Disease 2019 (COVID-19): A Review.

IMPORTANCE: The pandemic of coronavirus disease 2019 (COVID-19) caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) presents an unprecedented challenge to identify effective drugs for prevention and treatment. Given the rapid pace of scientific discovery and clinical data generated by the large number of people rapidly infected by SARS-CoV-2, clinicians need accurate evidence regarding effective medical treatments for this infection. OBSERVATIONS: No proven effective therapies for this virus currently exist. The rapidly expanding knowledge regarding SARS-CoV-2 virology provides a significant number of potential drug targets. The most promising therapy is remdesivir. Remdesivir has potent in vitro activity against SARS-CoV-2, but it is not US Food and Drug Administration approved and currently is being tested in ongoing randomized trials. Oseltamivir has not been shown to have efficacy, and corticosteroids are currently not recommended. Current clinical evidence does not support stopping angiotensin-converting enzyme inhibitors or angiotensin receptor blockers in patients with COVID-19. CONCLUSIONS AND RELEVANCE: The COVID-19 pandemic represents the greatest global public health crisis of this generation and, potentially, since the pandemic influenza outbreak of 1918. The speed and volume of clinical trials launched to investigate potential therapies for COVID-19 highlight both the need and capability to produce high-quality evidence even in the middle of a pandemic. No therapies have been shown effective to date.