The yin and yang of the universal transcription factor NusG.

RNA polymerase (RNAP), the central enzyme of transcription, intermittently pauses during the elongation stage of RNA synthesis. Pausing provides an opportunity for regulatory events such as nascent RNA folding or the recruitment of transregulators. NusG (Spt5 in eukaryotes and archaea) regulates RNAP pausing and is the only transcription factor conserved across all cellular life. NusG is a multifunctional protein: its N-terminal domain (NGN) binds to RNAP, and its C-terminal KOW domain in bacteria interacts with transcription regulators such as ribosomes and termination factors. In Escherichia coli, NusG acts as an antipausing factor. However, recent studies have revealed that NusG has distinct transcriptional regulatory roles specific to bacterial clades with clinical implications. Here, we focus on NusG's dual roles in the regulation of pausing.

The transcriptome of playfulness is sex-biased in the juvenile rat medial amygdala: a role for inhibitory neurons.

Social play is a dynamic behavior known to be sexually differentiated; in most species, males play more than females, a sex difference driven in large part by the medial amygdala (MeA). Despite the well-conserved nature of this sex difference and the importance of social play for appropriate maturation of brain and behavior, the full mechanism establishing the sex bias in play is unknown. Here, we explore "the transcriptome of playfulness" in the juvenile rat MeA, assessing differences in gene expression between high- and low-playing animals of both sexes via bulk RNA-sequencing. Using weighted gene co-expression network analysis (WGCNA) to identify gene modules combined with analysis of differentially expressed genes (DEGs), we demonstrate that the transcriptomic profile in the juvenile rat MeA associated with playfulness is largely distinct in males compared to females. Of the 13 play-associated WGCNA networks identified, only two were associated with play in both sexes, and very few DEGs associated with playfulness were shared between males and females. Data from our parallel single-cell RNA-sequencing experiments using amygdala samples from newborn male and female rats suggests that inhibitory neurons drive this sex difference, as the majority of sex-biased DEGs in the neonatal amygdala are enriched within this population. Supporting this notion, we demonstrate that inhibitory neurons comprise the majority of play-active cells in the juvenile MeA, with males having a greater number of play-active cells than females, of which a larger proportion are GABAergic. Through integrative bioinformatic analyses, we further explore the expression, function, and cell-type specificity of key play-associated modules and the regulator "hub genes" predicted to drive them, providing valuable insight into the sex-biased mechanisms underlying this fundamental social behavior.

Synthesis of propargyl glycosides of Streptococcus pneumoniae serotypes 6A and 6B for glycoconjugate vaccines.

We developed a method for making immune responses to bacterial glycans T cell-dependent, which involves attachment of short, synthetic glycans to a virus-like nanoparticle (VLP). This strategy enhances immune responses to glycans by facilitating cognate T cell help of B cells, leading to antibody class switching and affinity maturation yielding high-affinity, anti-glycan antibodies. This method requires synthesis of bacterial glycans as propargyl glycosides for covalent attachment to VLPs, and the resulting short linker between the VLP and glycan is important for optimal T cell receptor recognition. In this work, glycans that are part of the capsular polysaccharides (CPS) produced by Streptococcus pneumoniae serotypes Sp6A and Sp6B were synthesized as disaccharides and trisaccharides. The optimal glycan epitope for antibody binding to the CPS from these serotypes is unknown, and differing "frames" of disaccharides and trisaccharides were prepared to elucidate the optimal antigen for antibody binding.

Management of Bone Loss in Revision Total Knee Arthroplasty: An International Consensus Symposium.

The evaluation, classification, and treatment of significant bone loss after total knee arthroplasty (TKA) continue to be a complex and debated topic in revision TKA (rTKA). Despite the introduction of new evidence and innovative technologies aimed at addressing the approach and care of severe bone loss in rTKA, there is no single document that systematically incorporates these newer surgical approaches. Therefore, a comprehensive review of the treatment of severe bone loss in rTKA is necessary. The Stavros Niarchos Foundation Complex Joint Reconstruction Center Hospital for Special Surgery, dedicated to clinical care and research primarily in revision hip and knee replacement, convened a Management of Bone Loss in Revision TKA symposium on June 24, 2022. At this meeting, the 42 international invited experts were divided into groups; each group was assigned to discuss questions related to 1 of the 4 topics: (1) assessing preoperative workup and imaging, anticipated bone loss, classification system, and implant surveillance; (2) achieving durable fixation in the setting of significant bone loss in revision TKA; (3) managing patellar bone loss and the extensor mechanism in cases of severe bone loss; and (4) considering the use of complex modular replacement systems: hinges, distal femoral, and proximal tibial replacements. Each group came to consensus, when possible, based on an extensive literature review and interactive discussion on their group topic. This document reviews each these 4 areas, the consensus of each group, and directions for future research.

Early Recovery Outcomes in Patients Undergoing Contemporary Posterior Approach Total Hip Arthroplasty: Each Week Shows Progress.

Background: Little is known about patients' postoperative week-by-week progress after undergoing posterior approach total hip arthroplasty (THA) with regard to pain, function, return to work, and driving. Purpose: We sought to evaluate a large cohort of patients undergoing posterior approach THA with modified posterior hip precautions to better understand the trajectory of recovery. Methods: Patients at a single institution undergoing primary posterior approach THA by fellowship-trained arthroplasty surgeons were prospectively enrolled. Patient functional status and early rehabilitation recovery milestones were evaluated preoperatively and each week postoperatively for 6 weeks. Results: Of 312 patients who responded to weekly questionnaires, there were varying response rates per question. At 1 week after surgery, 15% (39/256) of respondents had returned to work, increasing to 57% (129/225) at week 6. At 6 weeks, 77% of patients (174/225) had returned to driving; 25% (56/225) were taking pain medication (including prescription opioids or nonsteroidal anti-inflammatory drugs); and 15% (34/225) were using assistive devices (down from 91%, 78%, 56%, 35%, and 27% at weeks 1, 2, 3, 4, and 5, respectively). Average postoperative Hip dysfunction and Osteoarthritis Outcome Score for Joint Replacement and Lower Extremity Functional Scale scores were significantly higher than preoperative scores. Respondents reported significantly less pain at each week postoperatively than the previous week. Conclusion: These findings suggest that there may be an expected pathway for recovery after posterior THA using perioperative pain protocols, modified postoperative precautions, and physical therapy protocols to improve patient outcomes after THA, with most patients returning to normal at 4 weeks. Defining the expected recovery timeline may help surgeons in counseling patients preoperatively and guiding their recovery.

Estimating the impact of addressing food needs on diabetes outcomes.

Objective: To estimate the association between food needs and diabetes outcomes. Research design and methods: Longitudinal cohort study, using a target trial emulation approach. 96,792 adults with type 2 diabetes mellitus who underwent food need assessment in a network of community-based health centers were followed up to 36 months after initial assessment. We used targeted minimum loss estimation to estimate the association between not experiencing food needs, compared with experiencing food needs, and hemoglobin a1c (HbA1c), systolic and diastolic blood pressure (SBP and DBP), and LDL cholesterol. The study period was June 24th, 2016 to April 30th, 2023. Results: We estimated that not experiencing food needs, compared with experiencing food needs, would be associated with 0.12 percentage points lower (95% Confidence Interval [CI] -0.16% to -0.09%, p = < 0.0001) mean HbA1c at 12 months. We further estimated that not experiencing food needs would be associated with a 12-month SBP that was 0.67 mm Hg lower (95%CI -0.97 to -0.38 mm Hg, p < .0001), DBP 0.21 mm Hg lower (95%CI -0.38 to -0.04 mm Hg, p = .01). There was no association with lower LDL cholesterol. Results were similar at other timepoints, with associations for HbA1c, SBP, and DBP of similar magnitude, and no difference in LDL cholesterol. Conclusions: We estimated that not experiencing food needs may be associated with modestly better diabetes outcomes. These findings support testing interventions that address food needs as part of their mechanism of action.

The development of surgical ability during pediatric urology fellowship and its evolution in the early years of practice.

BACKGROUND: North American Pediatric Urology fellowship programs underwent a structural change in 2021 that allows more flexibility in training. Given this opportunity as well as widespread concern about the development of contemporary surgical trainees, it is prudent to understand in detail the current state of preparedness of pediatric urology fellowship graduates for independent practice. OBJECTIVE: The study aimed to determine recent pediatric urology graduates' reported levels of comfort both at graduation and following the start of clinical practice in performing select index procedures. We also queried the aspects of training and clinical practice perceived to be the most valuable for the development of surgical confidence. STUDY DESIGN: Graduates of ACGME approved pediatric urology fellowships from 2016 to 2021 were surveyed. Index procedures were described via brief case vignettes. Respondents were asked to indicate their comfort level with each index procedure following fellowship graduation and at the current time point. Comfort levels were defined by the degree of support that respondents would seek from senior colleagues in preparation for case booking. Respondents were also asked about the most helpful operative settings during training and factors contributing to high and low comfort. RESULTS: Fifty-three pediatric urologists (49%) completed the survey out of 109 invited. Most respondents practiced at an academic center. Perceived comfort was very high for low complexity procedures. The responses varied more widely for procedures of moderate and significant complexity (Figure). Across the cohort, there was a substantial increase in comfort between graduation and the current time point for all procedures queried. The most highly valued operative settings in fellowship were those offering real or simulated independence. Respondents most often attributed high comfort to robust case volumes and overall surgical skill gained in fellowship. DISCUSSION: New pediatric urology faculty differ widely in surgical confidence, particularly for more complex procedures. There is meaningful growth in the confidence and self-perceived independence of pediatric urologists during their initial years of practice. The early years are a critical time of continuing maturation and development that should be supported with structured systems of mentorship. Future challenges include low case volumes for rare conditions and the centralization of complex care. CONCLUSION: These findings will provide valuable context for pediatric urology fellowship directors as they evaluate and redesign their programs under the new, more flexible structure. There are opportunities to formalize early practice mentorship to support the growth of new faculty.

Outcomes of internal fixation with Femoral Neck System (FNS) for intracapsular femoral neck fractures.

Background: Internal fixation of hip fractures is associated with high reoperation rates. This study investigated the reoperation rates after internal fixation with the femoral neck system (FNS). Materials and Methods: A single-institution cohort study was conducted on patients aged 18 years or older who sustained intracapsular femoral neck fractures and underwent internal fixation with a fixed-angle implant. Surgeons, patients, and investigators were not blinded. The primary outcome was any hip reoperation at the final follow-up. Secondary outcomes were to characterize a cohort of patients regarding demographics, fracture classification, intraoperative findings, postoperative fracture complications and union rates, and postoperative pain. Results: This study found that internal fixation with FNS for intracapsular femoral neck fractures was associated with a 23% rate of revision surgery. Of the initial 94 patients who received FNS internal fixation, 44 patients were included for analysis; of those, 10 patients underwent revision surgery. Patients had a 22% rate of in-hospital medical adverse events with a 30-day readmission rate of 9%. Increasing body mass index was associated with increased revision rates (P = 0.037). Patients who sustained displaced femoral neck fractures had a significant decrease in SF-12 Mental Health Composite, SF-12 Physical Health Composite, and quality-of-life subscale scores. Conclusions: The FNS is a viable alternative for internal fixation of intracapsular femoral neck fractures. The observed rate of revision after internal fixation was comparable with previously published outcomes following fixation with cannulated screws and sliding hip screws. Level of Evidence: Level IV, Therapeutic Study.

Objective performance indicators differ in obese and nonobese patients during robotic proctectomy.

BACKGROUND: Robotic surgery is perceived to be more complex in obese patients. Objective performance indicators, machine learning-enabled metrics, can provide objective data regarding surgeon movements and robotic arm kinematics. In this feasibility study, we identified differences in objective performance indicators during robotic proctectomy in obese and nonobese patients. METHODS: Endoscopic videos were annotated to delineate individual surgical steps across 39 robotic proctectomies (1880 total steps). Thirteen patients were obese and 26 were nonobese. Objective performance indicators during the following steps were analyzed: splenic flexure mobilization, left colon mobilization, pelvic dissection, and rectal transection. RESULTS: The following differences were noted during robotic proctectomy in obese patients: during splenic flexure mobilization, more arm swaps, longer camera path length and velocity; during left colon mobilization, longer step time, more arm swaps, higher camera-related metrics (movement, path length, velocity, acceleration, and jerk), greater dominant arm path length, moving time, and wrist articulation; during anterior pelvic dissection, longer energy activation time, camera path length, and moving time; during posterior pelvic dissection, lower nondominant arm velocity, jerk, and acceleration; during left pelvic dissection, longer energy activation time; during right pelvic dissection, greater camera-related metrics (movement, path length, moving time, and velocity); and during rectal transection, longer step time, more arm swaps, master clutch use and camera movements, greater dominant wrist articulation, and longer dominant arm path length. CONCLUSION: We report step-specific objective performance indicators that differ during robotic proctectomy for obese and nonobese patients. This is the first study to use objective performance indicators to correlate a patient attribute with surgeon movements and robotic arm kinematics during robotic colorectal surgery.

Objective Performance Indicators During Robotic Right Colectomy Differ According to Surgeon Skill.

INTRODUCTION: Surgeon assessment tools are subjective and nonscalable. Objective performance indicators (OPIs), machine learning-enabled metrics recorded during robotic surgery, offer objective insights into surgeon movements and robotic arm kinematics. In this study, we identified OPIs that significantly differed across expert (EX), intermediate (IM), and novice (NV) surgeons during robotic right colectomy. METHODS: Endoscopic videos were annotated to delineate 461 surgical steps across 25 robotic right colectomies. OPIs were compared among two EX, two IM, and eight NV surgeons during mesenteric dissection, vascular pedicle ligation, right colon and hepatic flexure mobilization, and preparation of the proximal and distal bowel for transection. RESULTS: Compared to NV's, EX's exhibited greater velocity, acceleration and jerk for camera, dominant, nondominant, and third arms across all steps. Compared to NV's, IM's exhibited more arm swaps and master clutch use, higher camera-related metrics (movement, path length, moving time, velocity, acceleration, and jerk), greater dominant wrist pitch and nondominant wrist articulations (roll, pitch, and yaw), longer dominant and nondominant arm path length, and higher velocity, acceleration and jerk for dominant, nondominant, and third arms across all steps. Compared to NV's, EX/IM surgeons utilized more arm swaps, higher camera-related metrics (movement, path length, velocity, acceleration, and jerk), longer nondominant arm path length, and greater velocity, acceleration and jerk for dominant, nondominant, and third arms across all steps. CONCLUSIONS: We report OPIs that discriminate EX, IM, and NV surgeons during RRC. This study is the first to demonstrate feasibility of using OPIs as an objective, scalable way to classify surgeon skill during RRC steps.

Association of hepatitis delta virus infection and hepatocellular carcinoma, hepatic decompensation, all-cause and liver-related death in a national cohort.

BACKGROUND: Hepatitis Delta Virus (HDV) infection is the most severe form of chronic hepatitis. However, studies on outcomes and causes of death in a United States-born population, with primarily horizontal transmission of HDV, are lacking. The aim of this study was to conduct a national study of patients with hepatitis D to understand the natural history and outcomes compared to patients with hepatitis B virus (HBV). infection. METHODS: In a national cohort of 4,817 HBV infected veterans tested for HDV (99.6% US-born, 3.3% HDV positive) over a 23-year period, we used multivariable models to identify the factors associated with a composite outcome of hepatocellular carcinoma (HCC), decompensation, and liver-related mortality (LRM), as well as all-cause mortality of patients with HDV compared to HBV mono-infection. RESULTS: HDV coinfection (vs. HBV monoinfection) was associated with a significantly higher incidence of composite liver-related outcomes at both 5 (23.84 vs. 7.98, p<0.001), and 10 years (19.14 vs. 10.18, p<0.001) respectively. The most common cause of death was liver-related (33.8% for HDV vs. 24.7% for HBV), followed by non-hepatic malignancies, (15.6 vs. 14.8%),cardiac (11.7 vs. 15.2%), and lung disease (5.2 vs. 3.7%). In multivariable models, HDV was associated with an increased risk of composite liver outcomes (aHR 2.57, 95% CI 1.87-3.52, p<0.001), and all-cause mortality (aHR 1.52, 95% CI 1.20-1.93, p<0.001). CONCLUSION: In a predominantly U.S born cohort of Veterans, HDV co-infection was associated with an increased risk of liver-related outcomes and all-cause mortality. Our findings support widespread testing for early identification of HDV.

Food Insecurity Prevalence and Risk Factors among Persons with HIV in a Southeastern US Clinical Care Setting.

Food insecurity (FI) is associated with adverse health outcomes for persons with HIV (PWH). Little is known about FI among PWH in southern or non-urban settings. We examined FI prevalence, risk factors, and access to services in a southeastern HIV clinic. Among PWH in the UNC CFAR HIV Clinical Cohort who were screened for FI as part of HIV care between 2021 and 2022, we estimated unadjusted prevalence ratios (PRs) comparing the probability of reporting FI by demographic and clinical characteristics. The 479 PWH screened for FI were 65% cisgender men, 62% non-Hispanic Black PWH, a median of 54 years old (IQR 41-62), and 93% with an HIV viral load (VL) < 200 copies/mL. FI prevalence was 36.3% (95% CI 32.3%-40.9%). Cisgender women and transgender adults were more likely to report FI than cisgender men (PRs 1.24 [95% CI 0.97-1.59] and 2.03 [1.32-3.12], respectively). Compared with White PWH, the PR was 1.71 (1.20-2.42) for Black and 2.44 (1.56-3.82) for Hispanic PWH. The PR was 1.42 (0.98-2.05) for PWH with VL ≥ 200 versus < 200 copies/mL. Having no or public versus private health insurance was also associated with FI. PWH with FI had a high prevalence of comorbidities including hypercholesterolemia (49%) and hypertension (48%), though these were not associated with FI. Almost half of PWH with FI were not accessing a food pantry or nutrition assistance program. Identifying FI in PWH is critical as FI is common and may contribute to viral non-suppression, poor comorbidity control, and gender and racial/ethnic health disparities in PWH.

Vagus nerve stimulation for stroke rehabilitation: Neural substrates, neuromodulatory effects and therapeutic implications.

Paired vagus nerve stimulation (VNS) has emerged as a promising strategy to potentiate recovery after neurological injury. This approach, which combines short bursts of electrical stimulation of the vagus nerve with rehabilitation exercises, received approval from the US Food and Drug Aministration in 2021 as the first neuromodulation-based therapy for chronic stroke. Because this treatment is increasingly implemented in clinical practice, there is a need to take stock of what we know about this approach and what we have yet to learn. Here, we provide a survey on the foundational basis of VNS therapy for stroke and offer insight into the mechanisms that underlie potentiated recovery, focusing on the principles of neuromodulatory reinforcement. We discuss the current state of observations regarding synaptic reorganization in motor networks that are enhanced by VNS, and we propose other prospective loci of neuromodulation that should be evaluated in the future. Finally, we highlight the future opportunities and challenges to be faced as this approach is increasingly translated to clinical use. Collectively, a clearer understanding of the mechanistic basis of VNS therapy may reveal ways to maximize its benefits.

Precision therapeutics and emerging strategies for HR-positive metastatic breast cancer.

Anti-oestrogen-based therapies, often combined with a CDK4/6 inhibitor, are the current standard-of-care first-line therapy for patients with advanced-stage hormone receptor-positive (HR+) breast cancer. Resistance to anti-oestrogen agents inevitably occurs, mediated by oestrogen receptor (ER)-dependent or ER-independent mechanisms that drive tumour progression. Emerging endocrine therapies include, but are not limited to, next-generation oral ER degraders and proteolysis targeting chimeras, which might be particularly effective in patients with ESR1-mutant breast cancer. Furthermore, cancers harbouring driver alterations in oncogenic signalling pathways, including AKT and PI3K, might be susceptible to novel combination strategies involving targeted inhibitors. Next-generation CDK2/4 inhibitors are an area of active clinical investigation, and efforts are ongoing to evaluate the role of sequential CDK inhibition. Approved and emerging antibody-drug conjugates exploiting novel target antigens have also demonstrated promising clinical activity. These novel agents, as well as further identification and characterization of predictive biomarkers, will hopefully continue to improve clinical outcomes, reduce the incidence of toxicities, and limit the extent of overtreatment in this population. In this Review, we describe the evolving treatment paradigm for patients with metastatic HR+ breast cancer in light of the growing armamentarium of drugs and biomarkers that will help to shape the future therapeutic landscape. These strategies are expected to involve tumour molecular profiling to enable the delivery of precision medicine.

SARS-CoV-2 Rapidly Infects Peripheral Sensory and Autonomic Neurons, Contributing to Central Nervous System Neuroinvasion before Viremia.

Neurological symptoms associated with COVID-19, acute and long term, suggest SARS-CoV-2 affects both the peripheral and central nervous systems (PNS/CNS). Although studies have shown olfactory and hematogenous invasion into the CNS, coinciding with neuroinflammation, little attention has been paid to susceptibility of the PNS to infection or to its contribution to CNS invasion. Here we show that sensory and autonomic neurons in the PNS are susceptible to productive infection with SARS-CoV-2 and outline physiological and molecular mechanisms mediating neuroinvasion. Our infection of K18-hACE2 mice, wild-type mice, and golden Syrian hamsters, as well as primary peripheral sensory and autonomic neuronal cultures, show viral RNA, proteins, and infectious virus in PNS neurons, satellite glial cells, and functionally connected CNS tissues. Additionally, we demonstrate, in vitro, that neuropilin-1 facilitates SARS-CoV-2 neuronal entry. SARS-CoV-2 rapidly invades the PNS prior to viremia, establishes a productive infection in peripheral neurons, and results in sensory symptoms often reported by COVID-19 patients.

Implications of using administrative healthcare data to identify risk of motor vehicle crash-related injury: the importance of distinguishing crash from crash-related injury.

BACKGROUND: Administrative healthcare databases, such as Medicare, are increasingly used to identify groups at risk of a crash. However, they only contain information on crash-related injuries, not all crashes. If the driver characteristics associated with crash and crash-related injury differ, conflating the two may result in ineffective or imprecise policy interventions. METHODS: We linked 10 years (2008-2017) of Medicare claims to New Jersey police crash reports to compare the demographics, clinical diagnoses, and prescription drug dispensings for crash-involved drivers ≥ 68 years with a police-reported crash to those with a claim for a crash-related injury. We calculated standardized mean differences to compare characteristics between groups. RESULTS: Crash-involved drivers with a Medicare claim for an injury were more likely than those with a police-reported crash to be female (62.4% vs. 51.8%, standardized mean difference [SMD] = 0.30), had more clinical diagnoses including Alzheimer's disease and related dementias (13.0% vs. 9.2%, SMD = 0.20) and rheumatoid arthritis/osteoarthritis (69.5% vs 61.4%, SMD = 0.20), and a higher rate of dispensing for opioids (33.8% vs 27.6%, SMD = 0.18) and antiepileptics (12.9% vs 9.6%, SMD = 0.14) prior to the crash. Despite documented inconsistencies in coding practices, findings were robust when restricted to claims indicating the injured party was the driver or was left unspecified. CONCLUSIONS: To identify effective mechanisms for reducing morbidity and mortality from crashes, researchers should consider augmenting administrative datasets with information from police crash reports, and vice versa. When those data are not available, we caution researchers and policymakers against the tendency to conflate crash and crash-related injury when interpreting their findings.

Contemporary Pediatric Heart Transplant Waitlist Mortality.

BACKGROUND: In 2016, the United Network for Organ Sharing revised its pediatric heart transplant (HT) allocation policy. OBJECTIVES: This study sought to determine whether the 2016 revisions are associated with reduced waitlist mortality and capture patient-specific risks. METHODS: Children listed for HT from 1999 to 2023 were identified using Organ Procurement and Transplantation Network data and grouped into 3 eras (era 1: 1999-2006; era 2: 2006-2016; era 3: 2016-2023) based on when the United Network for Organ Sharing implemented allocation changes. Fine-Gray competing risks modeling was used to identify factors associated with death or delisting for deterioration. Fixed-effects analysis was used to determine whether allocation changes were associated with mortality. RESULTS: Waitlist mortality declined 8 percentage points (PP) across eras (21%, 17%, and 13%, respectively; P < 0.01). At listing, era 3 children were less sick than era 1 children, with 6 PP less ECMO use (P < 0.01), 11 PP less ventilator use (P < 0.01), and 1 PP less dialysis use (P < 0.01). Ventricular assist device (VAD) use was 13 PP higher, and VAD mortality decreased 9 PP (P < 0.01). Non-White mortality declined 10 PP (P < 0.01). ABO-incompatible listings increased 27 PP, and blood group O infant mortality decreased 13 PP (P < 0.01). In multivariable analyses, the 2016 revisions were not associated with lower waitlist mortality, whereas VAD use (in era 3), ABO-incompatible transplant, improved patient selection, and narrowing racial disparities were. Match-run analyses demonstrated poor correlation between individual waitlist mortality risk and the match-run order. CONCLUSIONS: The 2016 allocation revisions were not independently associated with the decline in pediatric HT waitlist mortality. The 3-tier classification system fails to adequately capture patient-specific risks. A more flexible allocation system that accurately reflects patient-specific risks and considers transplant benefit is urgently needed.

Improving quality control procedures for the measurement of total daily energy expenditure using the two-point doubly labeled water method.

RATIONALE: The precision of the doubly labeled water (DLW) method is determined by the precision and accuracy of the isotopic measurements. Quality control (QC) procedures to mitigate sample variability require additional measurements if sample duplicates differ more than a factor of instrument precision. We explored the effect of widening QC ranges on total daily energy expenditure (TDEE) determined using the two-point sampling method. METHODS: We screened DLW data from 121 individuals for instances where samples were analyzed more than twice using our existing QC criteria (±2.0 per mil [δ] for 2H and ±0.5 δ for 18O). We then applied wider QC ranges for accepting duplicate measures and recalculated TDEE. RESULTS: Widening the 2H QC range to ±10.0 δ in samples collected on the first day (most enriched) and to ±5.0 δ in samples collected on the final day (less enriched) produced almost identical mean TDEE compared to the originally calculated TDEE (2684 ± 508 vs. 2687 ± 512 kcal/day, p = 0.40). There was a strong correlation with the originally calculated TDEE (r2 = 0.97, p < 0.001). CONCLUSIONS: Expanding the 2H QC range to ±10.0 δ for samples collected on the first day and ±5.0 δ for samples collected on the final day provides similar mean TDEE results. These findings may help DLW labs optimize QC criteria and reduce analytical costs.

Vagus nerve stimulation during training fails to improve learning in healthy rats.

Learning new skills requires neuroplasticity. Vagus nerve stimulation (VNS) during sensory and motor events can increase neuroplasticity in networks related to these events and might therefore serve to facilitate learning on sensory and motor tasks. We tested if VNS could broadly improve learning on a wide variety of tasks across different skill domains in healthy, female adult rats. VNS was paired with presentation of stimuli or on successful trials during training, strategies known to facilitate plasticity and improve recovery in models of neurological disorders. VNS failed to improve either rate of learning or performance for any of the tested tasks, which included skilled forelimb motor control, speech sound discrimination, and paired-associates learning. These results contrast recent findings from multiple labs which found VNS pairing during training produced learning enhancements across motor, auditory, and cognitive domains. We speculate that these contrasting results may be explained by key differences in task designs, training timelines and animal handling approaches, and that while VNS may be able to facilitate rapid and early learning processes in healthy subjects, it does not broadly enhance learning for difficult tasks.

Neural mechanisms responsible for vagus nerve stimulation-dependent enhancement of somatosensory recovery.

Impairments in somatosensory function are a common and often debilitating consequence of neurological injury, with few effective interventions. Building on success in rehabilitation for motor dysfunction, the delivery of vagus nerve stimulation (VNS) combined with tactile rehabilitation has emerged as a potential approach to enhance recovery of somatosensation. In order to maximize the effectiveness of VNS therapy and promote translation to clinical implementation, we sought to optimize the stimulation paradigm and identify neural mechanisms that underlie VNS-dependent recovery. To do so, we characterized the effect of tactile rehabilitation combined with VNS across a range of stimulation intensities on recovery of somatosensory function in a rat model of chronic sensory loss in the forelimb. Consistent with previous studies in other applications, we find that moderate intensity VNS yields the most effective restoration of somatosensation, and both lower and higher VNS intensities fail to enhance recovery compared to rehabilitation without VNS. We next used the optimized, moderate intensity to evaluate the mechanisms that underlie recovery. We find that moderate intensity VNS enhances transcription of Arc, a canonical mediator of synaptic plasticity, in the cortex, and that transcript levels were correlated with the degree of somatosensory recovery. Moreover, we observe that blocking plasticity by depleting acetylcholine in the cortex prevents the VNS-dependent enhancement of somatosensory recovery. Collectively, these findings identify neural mechanisms that subserve VNS-dependent somatosensation recovery and provide a basis for selecting optimal stimulation parameters in order to facilitate translation of this potential intervention.