Single-cell RNA sequencing (scRNA-Seq) is emerging as a powerful technology to examine transcriptomes of individual cells. We determined whether scRNA-Seq could be used to detect the effect of environmental and pharmacologic perturbations on osteoblasts. We began with a commonly used in vitro system in which freshly isolated neonatal mouse calvarial cells are expanded and induced to produce a mineralized matrix. We used scRNA-Seq to compare the relative cell type abundances and the transcriptomes of freshly isolated cells to those that had been cultured for 12 days in vitro. We observed that the percentage of macrophage-like cells increased from 6% in freshly isolated calvarial cells to 34% in cultured cells. We also found that Bglap transcripts were abundant in freshly isolated osteoblasts but nearly undetectable in the cultured calvarial cells. Thus, scRNA-Seq revealed significant differences between heterogeneity of cells in vivo and in vitro. We next performed scRNA-Seq on freshly recovered long bone endocortical cells from mice that received either vehicle or sclerostin-neutralizing antibody for 1 week. We were unable to detect significant changes in bone anabolism-associated transcripts in immature and mature osteoblasts recovered from mice treated with sclerostin-neutralizing antibody; this might be a consequence of being underpowered to detect modest changes in gene expression, because only 7% of the sequenced endocortical cells were osteoblasts and a limited portion of their transcriptomes were sampled. We conclude that scRNA-Seq can detect changes in cell abundance, identity, and gene expression in skeletally derived cells. In order to detect modest changes in osteoblast gene expression at the single-cell level in the appendicular skeleton, larger numbers of osteoblasts from endocortical bone are required.

Current limitations in technology have prevented an extensive analysis of the connections among neurons, particularly within nonmammalian organisms. We developed a transsynaptic viral tracer originally for use in mice, and then tested its utility in a broader range of organisms. By engineering the vesicular stomatitis virus (VSV) to encode a fluorophore and either the rabies virus glycoprotein (RABV‐G) or its own glycoprotein (VSV‐G), we created viruses that can transsynaptically label neuronal circuits in either the retrograde or anterograde direction, respectively. The vectors were investigated for their utility as polysynaptic tracers of chicken and zebrafish visual pathways. They showed patterns of connectivity consistent with previously characterized visual system connections, and revealed several potentially novel connections. Further, these vectors were shown to infect neurons in several other vertebrates, including Old and New World monkeys, seahorses, axolotls, and Xenopus. They were also shown to infect two invertebrates, Drosophila melanogaster, and the box jellyfish, Tripedalia cystophora, a species previously intractable for gene transfer, although no clear evidence of transsynaptic spread was observed in these species. These vectors provide a starting point for transsynaptic tracing in most vertebrates, and are also excellent candidates for gene transfer in organisms that have been refractory to other methods. J. Comp. Neurol. 523:1639–1663, 2015. © 2015 Wiley Periodicals, Inc.

The brain has a tightly regulated environment that protects neurons and limits inflammation, designated "immune privilege." However, there is not an absolute lack of an immune response. We tested the ability of the brain to initiate an innate immune response to a virus, which was directly injected into the brain parenchyma, and to determine whether this response could limit viral spread. We injected vesicular stomatitis virus (VSV), a transsynaptic tracer, or naturally occurring VSV-derived defective interfering particles (DIPs), into the caudate-putamen (CP) and scored for an innate immune response and inhibition of virus spread. We found that the brain parenchyma has a functional type I interferon (IFN) response that can limit VSV spread at both the inoculation site and among synaptically connected neurons. Furthermore, we characterized the response of microglia to VSV infection and found that infected microglia produced type I IFN and uninfected microglia induced an innate immune response following virus injection.

IMPORTANCE There are limited data to guide screen time recommendations after concussion. OBJECTIVE To determine whether screen time in the first 48 hours after concussion has an effect on the duration of concussive symptoms.DESIGN, SETTING, AND PARTICIPANTS This randomized clinical trial was conducted in the pediatric and adult emergency departments of a tertiary medical center between June 2018 and February 2020. Participants included a convenience sample of patients aged 12 to 25 years presenting to the emergency department within 24 hours of sustaining a concussion. A total of 162 patients were approached, 22 patients met exclusion criteria, and 15 patients declined participation; 125 participants were enrolled and randomized.INTERVENTIONS Patients were either permitted to engage in screen time (screen time permitted group) or asked to abstain from screen time (screen time abstinent group) for 48 hours after injury. MAIN OUTCOMES AND MEASURESThe primary outcome was days to resolution of symptoms, defined as a total Post-Concussive Symptom Scale (PCSS) score of 3 points or lower. Patients completed the PCSS, a 22-symptom scale that grades each symptom from 0 (not present) to 6 (severe), each day for 10 days. Kaplan-Meier curves and Cox regression modeling were used to compare the 2 groups. A Wilcoxon rank sum test was also performed among participants who completed the PCSS each day through recovery or conclusion of the study period. RESULTS Among 125 patients with concussion, the mean (SD) age was 17.0 (3.4) years; 64 participants (51.2%) were male. A total of 66 patients were randomized to the screen time permitted group, and 59 patients were randomized to the screen time abstinent group. The Cox regression model including the intervention group and the patient's self-identified sex demonstrated a significant effect of screen time (hazard ratio [HR], 0.51; 95% CI, 0.29-0.90), indicating that participants who engaged in screen time were less likely to recover during the study period. In total, 91 patients were included in the Wilcoxon rank sum test (47 patients from the screen time permitted group, and 44 patients from the screen time abstinent group). The screen time permitted group had a significantly longer median recovery time of 8.0 days (interquartile range [IQR], 3.0 to >10.0 days) compared with 3.5 days (IQR, 2.0 to >10.0 days; P = .03) in the screen time abstinent group. The screen time permitted group reported a median screen time of 630 minutes (IQR, 415-995 minutes) during the intervention period compared with 130 minutes (IQR, 61-275 minutes) in the screen time abstinent group. CONCLUSIONS AND RELEVANCEThe findings of this study indicated that avoiding screen time during acute concussion recovery may shorten the duration of symptoms. A multicenter study would help to further assess the effect of screen time exposure. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT03564210

The SPIN score, a logistic regression-based clinical risk stratification scale estimating survival after pTBI, was developed in this large, diverse 2-center cohort. While this preliminary clinical survival prediction tool does not include radiologic factors, it may support clinical decision-making after civilian pTBI if external validation confirms the probability estimates.

Understanding and addressing gaps in ACS implementation across communities will be crucial to ensuring health equity for US residents experiencing general surgery emergencies.

Background: There is a need to understand the performance of rapid antigen tests (Ag-RDT) for detection of the Delta (B.1.61.7; AY.X) and Omicron (B.1.1.529; BA1) SARS-CoV-2 variants. Methods: Participants without any symptoms were enrolled from October 18, 2021 to January 24, 2022 and performed Ag-RDT and RT-PCR tests every 48 hours for 15 days. This study represents a non-pre-specified analysis in which we sought to determine if sensitivity of Ag-RDT differed in participants with Delta compared to Omicron variant. Participants who were positive on RT-PCR on the first day of the testing period were excluded. Delta and Omicron variants were defined based on sequencing and date of first RT-PCR positive result (RT-PCR+). Comparison of Ag-RDT performance between the variants was based on proportion of participants with Ag-RDT+ results in relation to their first RT-PCR+ result. Subsample analysis was performed based on the result of participants′ second RT-PCR test within 48 hours of the first RT-PCR+ test. Results: From the 7,349 participants enrolled in the parent study, 5,506 met the eligibility criteria for this study. A total of 153 participants were RT-PCR+ (61 Delta, 92 Omicron); among this group, 36 (23.5%) tested Ag-RDT+ on the same day and 36 (23.5%) tested Ag-RDT+ within 48 hours as first RT-PCR+. The differences between variants were not statistically significant (same-day: Delta 16.4% [95% CI: 8.2-28.1] vs Omicron 28.2% [95% CI: 19.4-38.6; 48-hours: Delta 45.9% [33.1-59.2] vs. Omicron 60.9% [50.1-70.9]). This trend continued among the 86 participants who had consecutive RT-PCR+ result (Delta: 79.3% [60.3-92.1] vs. Omicron: 89.5% [78.5-96.0]). Conversely, the 38 participants who had an isolated positive RT-PCR remained consistently negative on Ag-RDT, regardless of the variant. Conclusions: The performance of Ag-RDT is not inferior among Omicron variant in comparison to the Delta variant. The improvement in sensitivity of Ag-RDT with serial testing is consistent between Delta and Omicron variant. Performance of Ag-RDT varies based on duration of RT-PCR+ results and more studies are needed to understand the clinical and public health significance of individuals who are RT-PCR+ for less than 48 hours.

Use of rapid tests for diagnosis of COVID-19 is now commonplace, but questions remain regarding their performance characteristics compared with those of polymerase chain reaction testing. The role of sequential rapid testing in improving sensitivity is of great interest.