Preclinical studies in models of neurological injury and disease rely upon behavioral outcomes to measure intervention efficacy. For spinal cord injury, the CatWalk system provides unbiased quantitative assessment of subtle aspects of locomotor function in rodents and so can powerfully detect significant differences between experimental and control groups. Although clearly of key importance, summary group-level data can obscure the variability within and between individual subjects and therefore make it difficult to understand the magnitude of effect in individual animals and the proportion of a group that may show benefit. Here we calculate 'reference change intervals' that define boundaries of normal variability for measures of rat locomotion on the CatWalk. Our results indicate that many commonly-used outcome measures are highly variable, such that differences of up to 70% from baseline value must be considered normal variation. Many CatWalk outcome variables are also highly correlated and dependent upon run speed. Application of calculated reference change intervals to open access data (odc-sci.org) on hindlimb stride length in spinal cord-injured rats illustrates the complementarity between group-level (16mm change; P=0.0009) and individual-level (5/32 animals show change outside reference change interval boundaries) analysis between week 3 and week 6 after injury. We also conclude that interdependence amongst CatWalk variables implies that test 'batteries' require careful composition to ensure that different aspects of defective gait are analyzed. Calculation of reference change intervals aids in experimental design by quantifying variability and enriches overall data analysis by providing details of change at an individual level that complement group-level analysis. Significance statement Selection of robust candidate interventions for translation from experimental animals into the neurology clinic requires meticulous examination of behavioral effects observed in the laboratory. Although analysis of group-level data, the current mainstay, is critically 4 important, analysis of individual-level data provides a complementary viewpoint that, bearing in mind the immense variability in neurological deficits in people with spinal cord injury, has high relevance to the interpretation of studies on putative therapies. Here we describe the derivation of specific 'reference change intervals' and, using example data, show how these augment interpretation of overall effect and can aid in effective experimental design. The combination of group-level and individual-level analysis will provide more stringent analysis of intervention effects in neurological injury and disease research.

Through many decades of preclinical research, great progress has been achieved in understanding the complex nature of spinal cord injury (SCI). Preclinical research efforts have guided and shaped clinical trials, which are growing in number by the year. Currently, 1,149 clinical trials focused on improving outcomes after SCI are registered in the U.S. National Library of Medicine at ClinicalTrials.gov. We conducted a systematic analysis of these SCI clinical trials, using publicly accessible data downloaded from ClinicalTrials.gov. After extracting all available data for these trials, we categorized each trial according to the types of interventions being tested and the types of outcomes assessed. We then evaluated clinical trial characteristics, both globally and by year, in order to understand the areas of growth and change over time. With regard to clinical trial attributes, we found that most trials have low enrollment, only test single interventions, and have limited numbers of primary outcomes. Some gaps in reporting are apparent; for instance, over 75% of clinical trials with “Completed” status do not have results posted, and the Phase of some trials is incorrectly classified as “Not applicable” despite testing a drug or biological compound. When analyzing trials based on types of interventions assessed, we identified the largest representation in trials testing rehab/training/exercise, neuromodulation, and behavioral modifications. Most highly represented primary outcomes include motor function of the upper and lower extremities, safety, and pain. The most highly represented secondary outcomes include quality of life and pain. Over the past 15 years, we identified increased representation of neuromodulation and rehabilitation trials, and decreased representation of drug trials. Overall, the number of new clinical trials initiated each year continues to grow, signifying a hopeful future for the clinical treatment of SCI. Together, our work provides a comprehensive glimpse into the past, present, and future of SCI clinical trials, and suggests areas for improvement in clinical trial reporting.

Despite advancement of neural progenitor cell transplantation to spinal cord injury clinical trials, there remains a lack of understanding of how biological sex of transplanted cells influences outcomes after transplantation. To address this, we transplanted GFP-expressing sex-matched, sex-mismatched, or mixed donor cells into sites of spinal cord injury in adult male and female mice. Biological sex of the donor cells does not influence graft neuron density, glial differentiation, formation of the reactive glial cell border, or graft axon outgrowth. However, male grafts in female hosts feature extensive hypervascularization accompanied by increased vascular diameter and perivascular cell density. We show greater T-cell infiltration within male-to-female grafts than other graft types. Together, these findings indicate a biological sex-specific immune response of female mice to male donor cells. Our work suggests that biological sex should be considered in the design of future clinical trials for cell transplantation in human injury.

Plants on serpentine soils provide extreme examples of adaptation to environment, and thus offer excellent models for the study of evolution at the molecular and genomic level. Serpentine outcrops are derived from ultramafic rock and have extremely low levels of essential plant nutrients (e.g., N, P, K, and Ca), as well as toxic levels of heavy metals (e.g., Ni, Cr, and Co) and low moisture availability. These outcrops provide habitat to a number of endemic plant species, including the annual mustard Caulanthus amplexicaulis var. barbarae (Cab) (Brassicaceae). Its sister taxon, C. amplexicaulis var. amplexicaulis (Caa), is intolerant to serpentine soils. Here, we assembled and annotated comprehensive reference transcriptomes of both Caa and Cab for use in protein coding sequence comparisons. A set of 29,443 reciprocal best Blast hit (RBH) orthologs between Caa and Cab was compared with identify coding sequence variants, revealing a high genome-wide dN/dS ratio between the two taxa (mean = 0.346). We show that elevated dN/dS likely results from the composite effects of genetic drift, positive selection, and the relaxation of negative selection. Further, analysis of paralogs within each taxon revealed the signature of a period of elevated gene duplication (∼10 Ma) that is shared with other species of the tribe Thelypodieae, and may have played a role in the striking morphological and ecological diversity of this tribe. In addition, distribution of the synonymous substitution rate, dS, is strongly bimodal, indicating a history of reticulate evolution that may have contributed to serpentine adaptation.