Quantification of functional recovery in a larval zebrafish model of spinal cord injury.

Human spinal cord injury (SCI) is characterized by permanent loss of damaged axons, resulting in chronic disability. In contrast, zebrafish can regenerate axonal projections following central nervous system injury and re-establish synaptic contacts with distant targets; elucidation of the underlying molecular events is an important goal with translational potential for improving outcomes in SCI patients. We generated transgenic zebrafish with GFP-labeled axons and transected their spinal cords at 10 days post-fertilization. Intravital confocal microscopy revealed robust axonal regeneration following the procedure, with abundant axons bridging the transection site by 48 h post-injury. In order to analyze neurological function in this model, we developed and validated new open-source software to measure zebrafish lateral trunk curvature during propulsive and turning movements at high temporal resolution. Immediately following spinal cord transection, axial movements were dramatically decreased caudal to the lesion site, but preserved rostral to the injury, suggesting the induction of motor paralysis below the transection level. Over the subsequent 96 h, the magnitude of movements caudal to the lesion recovered to baseline, but the rate of change of truncal curvature did not fully recover, suggesting incomplete restoration of caudal strength over this time course. Quantification of both morphological and functional recovery following SCI will be important for the analysis of axonal regeneration and downstream events necessary for restoration of motor function. An extensive array of genetic and pharmacological interventions can be deployed in the larval zebrafish model to investigate the underlying molecular mechanisms.

What gets resident physicians stressed and how would they prefer to be supported? A best-worst scaling study.

INTRODUCTION: Physician burnout has severe consequences on clinician well-being. Residents face numerous work-stressors that can contribute to burnout; however, given specialty variation in work-stress, it is difficult to identify systemic stressors and implement effective burnout interventions on an institutional level. Assessing resident preferences by specialty for common wellness interventions could also contribute to improved efficacy. METHODS: This cross-sectional study used best-worst scaling (BWS), a type of discrete choice modelling, to explore how 267 residents across nine specialties (anaesthesiology, emergency medicine, internal medicine, neurology, obstetrics and gynaecology, pathology, psychiatry, radiology and surgery) prioritised 16 work-stressors and 4 wellness interventions at a large academic medical centre during the COVID-19 pandemic (December 2020). RESULTS: Top-ranked stressors were work-life integration and electronic health record documentation. Therapy (63%, selected as 'would realistically consider intervention') and coaching (58%) were the most preferred wellness supports in comparison to group-based peer support (20%) and individual peer support (22%). Pathology, psychiatry and OBGYN specialties were most willing to consider all intervention options, with emergency medicine and internal medicine specialties least willing to consider intervention options. CONCLUSION: BWS can identify relative differences in surveyed stressors, allowing for the generation of specialty-specific stressor rankings and preferences for specific wellness interventions that can be used to drive institution-wide changes to improve clinician wellness. BWS surveys are a potential methodology for clinician wellness programmes to gather specific information on preferences to determine best practices for resident wellness.

The Burden of Guardianship: A Matched Cohort Study.

BACKGROUND: In cases where patients are unable to provide informed consent and have no surrogate decisionmaker, a hospital must seek guardian appointment as a legally recognized surrogate decision-maker. OBJECTIVE: The aim of this study was to examine the magnitudes of length of stay (LOS) beyond medical clearance and healthcare costs among patients referred for guardianship. DESIGN, SETTING, PATIENTS: This was a retrospective cohort study of all 61 adult inpatients in a single tertiary care hospital requiring guardianship between October 1, 2014, and September 30, 2015, matched with up to 3 controls from the same discharging services and hospitalized for at least as long as the date of clearance for referred patients. MEASUREMENTS: The following parameters were measured using generalized estimating equations: total LOS, LOS beyond medical clearance (excess LOS), medical complications, and total charges among referred patients, and the LOS and costs were compared with those of matched controls. RESULTS: Mean LOS for patients requiring guardianship was 31 ± 2 days, and the total charges averaged $179,243 ± 22,950. We documented 12 hospital-acquired complications in 10 (16%; 95% confidence interval [CI], 8%-28%) unique patients. Accounting for potential confounders, the process of obtaining guardianship was associated with a 37% longer total LOS (95% CI [12%- 67%]; P = .002), 58% higher excess LOS (95% CI [2%- 145%]; P = .04), and 23% higher total charges (95% CI [4%-46%]; P = .02). CONCLUSIONS: In this single-center cohort study, the guardianship process was associated with prolonged hospital stay and higher total hospital charges even when compared with matched controls. Furthermore, one in six patients suffered from a hospital-associated complication after medical clearance.

Different mechanisms regulate expression of zebrafish myelin protein zero (P0) in myelinating oligodendrocytes and its induction following axonal injury.

Zebrafish CNS axons regenerate robustly following injury; it is thought that CNS oligodendrocytes contribute to this response by expressing growth-promoting molecules. We characterized the mpz gene, which encodes myelin protein zero and is up-regulated in oligodendroglia following axonal injury. The 2.5-kb mpz mRNA is expressed from a single TATA box promoter. Four independent Tg(mpz:egfp) transgenic zebrafish lines, in which GFP was expressed under the mpz promoter and 10 kb of genomic 5'-flanking sequence, showed transgene expression in CNS oligodendrocytes from larval development through adulthood. Following optic nerve crush injury, the mpz:egfp transgene was strongly up-regulated in oligodendrocytes along the regenerating retinotectal projection, mirroring up-regulation of endogenous mpz mRNA. GFP-expressing oligodendroglia were significantly more abundant in the regenerating optic pathway, resulting from both transgene induction in oligodendroglial precursors and the birth of new cells. Up-regulation of the mpz:egfp transgene was not dependent on axonal regeneration, suggesting that the primary signal may be axonal loss, debris, or microglial infiltration. Deletion experiments indicated that an oligodendroglial enhancer located in the region from -6 to -10 kb with respect to the mpz transcriptional start site is dissociable from the cis-regulatory element mediating the mpz transcriptional response to axonal injury, which is located between -1 and -4 kb. These data show that different mechanisms regulate expression of zebrafish mpz in myelinating oligodendrocytes and its induction following axonal injury. The underlying molecular events could potentially be exploited to enhance axonal repair following mammalian CNS injury. The transgenic lines and cis-regulatory constructs reported here will facilitate identification of the relevant signaling pathways.