SUMMARY The generation of distinct hematopoietic cell types, including tissue-resident immune cells, distinguishes fetal from adult hematopoiesis. However, the mechanisms underlying differential cell production to generate a layered immune system during hematopoietic development are unclear. Using an irreversible lineage tracing model, we identify a definitive hematopoietic stem cell (HSC) that supports long-term multilineage reconstitution upon transplantation into adult recipients, but does not persist into adulthood in situ. These HSCs are fully multipotent, yet display both higher lymphoid cell production and greater capacity to generate innate-like B and T lymphocytes as compared to coexisting fetal HSCs and adult HSCs. Thus, these developmentally restricted HSCs define the origin and generation of early lymphoid cells that play essential roles in establishing self-recognition and tolerance, with important implications for understanding autoimmune disease, allergy, and rejection of transplanted organs.

Background The prevalence of depression among patients in the emergency department (ED) is significantly higher than in the general population, making the ED a potentially important forum for the identification of depression and intervention. Concomitant to the identification of depression is the issue of patient access to appropriate care. Objectives This study sought to establish prevalence estimates of potential barriers to care among ED patients and relate these barriers with symptoms of depression. Methods Two medical students conducted brief surveys on all ED patients ≥ 18 years on demographics, perceived access to care, and depression. Results A total of 636 participants were enrolled. The percentage of participants with mild or greater depression was 42%. The majority of patients reported experiencing some barriers to care, with the most prominent being difficulty finding transportation, work responsibilities, and the feeling that the doctor is not responsive to their concerns. Higher depression scores were bivariately associated with higher overall barriers to care mean scores (r=0.44, p<0.001), suggesting that greater symptoms of depression are associated with greater difficulties accessing care. Particularly strong associations were observed between symptoms of depression and difficulty finding transportation, the feeling that the doctor is not responsive to patients’ concerns, embarrassment about a potential illness and confusion trying to schedule an appointment. Conclusion Across all barriers analyzed, there was a greater incidence of depression associated with a greater perception of barriers. These barriers may be used as potential targets for intervention to increase access to health care resources.

Introduction Emergency department (ED) patients experience a variety of barriers to care that can lead to unnecessary or repeated visits. By identifying the patterns of barriers experienced by subsets of the ED patient population, future researchers might effectively design interventions to circumvent these barriers and improve care. This study sought to identify classes of individuals with regard to perceived barriers to care. Methods Over a 10-week period, two medical students distributed surveys to eligible patients ≥18 years who presented to the ED. After consent, patients provided demographics data and rated their perceived access to care on nine specific items (scored 1–5). We used latent class analysis (LCA), a parametric clustering method, to determine patient groups. Demographic characteristics were then compared across classes. Results We enrolled a total of 637 patients. Results of the LCA indicated that a six-class solution fit best: 1) low barriers (60%); 2) “work responsibility” barriers (13%); 3) economic-related barriers (10%); 4) “appointment difficulty” barriers (8%); 5) “illness and care responsibilities” barriers (6%); and 6) diverse barriers (2%). Patients in the low-barriers class were the oldest across classes (p<.001). Individuals in the low-barriers class were also more likely to be White (p=.015) and have private insurance (p<.001) than those in the “appointment difficulty,” “illness and care responsibilities,” and diverse barriers classes. Conclusion LCA suggests there are six distinct classes of patients with regard to perceived access to care. These classes may be used as a potential starting point in designing targeted interventions for ED patients to improve continuity of care.

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