Abstract Objective To explore the work lives, professional satisfaction, and burnout of US physicians by career stage and differences across sexes, specialties, and practice setting. Participants and ...Methods We conducted a cross-sectional study that involved a large sample of US physicians from all specialty disciplines in June 2011. The survey included the Maslach Burnout Inventory and items that explored professional life and career satisfaction. Physicians who had been in practice 10 years or less, 11 to 20 years, and 21 years or more were considered to be in early, middle, and late career, respectively. Results Early career physicians had the lowest satisfaction with overall career choice (being a physician), the highest frequency of work-home conflicts, and the highest rates of depersonalization (all P <.001). Physicians in middle career worked more hours, took more overnight calls, had the lowest satisfaction with their specialty choice and their work-life balance, and had the highest rates of emotional exhaustion and burnout (all P <.001). Middle career physicians were most likely to plan to leave the practice of medicine for reasons other than retirement in the next 24 months (4.8%, 12.5%, and 5.2% for early, middle, and late career, respectively). The challenges of middle career were observed in both men and women and across specialties and practice types. Conclusion Burnout, satisfaction, and other professional challenges for physicians vary by career stage. Middle career appears to be a particularly challenging time for physicians. Efforts to promote career satisfaction, reduce burnout, and facilitate retention need to be expanded beyond early career interventions and may need to be tailored by career stage.
Renal disease is growing in prevalence and has striking co-morbidities with metabolic and cardiovascular disease. Indoxyl sulfate (IS) is a toxin that accumulates in plasma when kidney function ...declines and contributes to the progression of chronic kidney disease. IS derives exclusively from the gut microbiota. Bacterial tryptophanases convert tryptophan to indole, which is absorbed and modified by the host to produce IS. Here, we identify a widely distributed family of tryptophanases in the gut commensal Bacteroides and find that deleting this gene eliminates the production of indole in vitro. By altering the status or abundance of the Bacteroides tryptophanase, we can modulate IS levels in gnotobiotic mice and in the background of a conventional murine gut community. Our results demonstrate that it is possible to control host IS levels by targeting the microbiota and suggest a possible strategy for treating renal disease.
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•Indole-producing tryptophanases (Tnases) in Bacteroides are identified computationally•Tnase activity and its control of indoxyl sulfate (IS) levels in vivo are established•Rational diet alteration in gnotobiotic mice with a synthetic community controls IS level•Colonization with Tnase-deficient Bacteroides lowers IS in conventional mice
Devlin et al. identify a widely distributed family of indole-producing tryptophanases in commensal gut bacteria. Using this information, they engineer bacteria to control in vivo production of the downstream product, the uremic toxin indoxyl sulfate. These results suggest a new strategy for treating chronic kidney disease by targeting the microbiome.
There is significant need to develop physiologically relevant models for investigating human astrocytes in health and disease. Here, we present an approach for generating astrocyte lineage cells in a ...three-dimensional (3D) cytoarchitecture using human cerebral cortical spheroids (hCSs) derived from pluripotent stem cells. We acutely purified astrocyte-lineage cells from hCSs at varying stages up to 20 months in vitro using immunopanning and cell sorting and performed high-depth bulk and single-cell RNA sequencing to directly compare them to purified primary human brain cells. We found that hCS-derived glia closely resemble primary human fetal astrocytes and that, over time in vitro, they transition from a predominantly fetal to an increasingly mature astrocyte state. Transcriptional changes in astrocytes are accompanied by alterations in phagocytic capacity and effects on neuronal calcium signaling. These findings suggest that hCS-derived astrocytes closely resemble primary human astrocytes and can be used for studying development and modeling disease.
•Up to 590-day cultures of human iPSC-derived 3D cortical spheroids (hCSs)•Transcriptional and functional characterization of astrocytes purified from hCSs•Astrocytes within hCSs mature during in vitro differentiation•Early- and late-stage hCS-derived astrocytes are functionally distinct
Sloan et al. developed a method for generating and purifying astrocytes from 3D cerebral cortical spheroids derived from human pluripotent cells. Long-term culture (∼20 months in vitro) and direct comparison to human primary cells reveal transcriptional and functional astrocyte maturation.
Significance The brain comprises an immense number of cells and cellular connections. We describe the first, to our knowledge, single cell whole transcriptome analysis of human adult cortical ...samples. We have established an experimental and analytical framework with which the complexity of the human brain can be dissected on the single cell level. Using this approach, we were able to identify all major cell types of the brain and characterize subtypes of neuronal cells. We observed changes in neurons from early developmental to late differentiated stages in the adult. We found a subset of adult neurons which express major histocompatibility complex class I genes and thus are not immune privileged.
The human brain is a tissue of vast complexity in terms of the cell types it comprises. Conventional approaches to classifying cell types in the human brain at single cell resolution have been limited to exploring relatively few markers and therefore have provided a limited molecular characterization of any given cell type. We used single cell RNA sequencing on 466 cells to capture the cellular complexity of the adult and fetal human brain at a whole transcriptome level. Healthy adult temporal lobe tissue was obtained during surgical procedures where otherwise normal tissue was removed to gain access to deeper hippocampal pathology in patients with medical refractory seizures. We were able to classify individual cells into all of the major neuronal, glial, and vascular cell types in the brain. We were able to divide neurons into individual communities and show that these communities preserve the categorization of interneuron subtypes that is typically observed with the use of classic interneuron markers. We then used single cell RNA sequencing on fetal human cortical neurons to identify genes that are differentially expressed between fetal and adult neurons and those genes that display an expression gradient that reflects the transition between replicating and quiescent fetal neuronal populations. Finally, we observed the expression of major histocompatibility complex type I genes in a subset of adult neurons, but not fetal neurons. The work presented here demonstrates the applicability of single cell RNA sequencing on the study of the adult human brain and constitutes a first step toward a comprehensive cellular atlas of the human brain.
Bile acids act as signaling molecules that regulate immune homeostasis, including the differentiation of CD4+ T cells into distinct T cell subsets. The bile acid metabolite isoallolithocholic acid ...(isoalloLCA) enhances the differentiation of anti-inflammatory regulatory T cells (Treg cells) by facilitating the formation of a permissive chromatin structure in the promoter region of the transcription factor forkhead box P3 (Foxp3). Here, we identify gut bacteria that synthesize isoalloLCA from 3-oxolithocholic acid and uncover a gene cluster responsible for the conversion in members of the abundant human gut bacterial phylum Bacteroidetes. We also show that the nuclear hormone receptor NR4A1 is required for the effect of isoalloLCA on Treg cells. Moreover, the levels of isoalloLCA and its biosynthetic genes are significantly reduced in patients with inflammatory bowel diseases, suggesting that isoalloLCA and its bacterial producers may play a critical role in maintaining immune homeostasis in humans.
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•Microbially derived secondary bile acid isoalloLCA enhances Treg differentiation•A biosynthetic gene cluster in gut Bacteroidetes converts 3-oxoLCA to isoalloLCA•NR4A1 is required for the isoalloLCA-mediated differentiation of Treg cells•Levels of isoalloLCA and corresponding genes are negatively correlated with IBD
Li and Hang et al. identify a biosynthetic pathway by which abundant human gut bacterial species from the phylum Bacteroidetes convert the secondary bile acid 3-oxoLCA to isoalloLCA. The nuclear hormone receptor NR4A1 is required for isoalloLCA to enhance Treg cell differentiation, suggesting a commensal-driven mechanism of immune tolerance.
The standard approach for documenting symptomatic adverse events (AEs) in cancer clinical trials involves investigator reporting using the National Cancer Institute's (NCI's) Common Terminology ...Criteria for Adverse Events (CTCAE). Because this approach underdetects symptomatic AEs, the NCI issued two contracts to create a patient-reported outcome (PRO) measurement system as a companion to the CTCAE, called the PRO-CTCAE. This Commentary describes development of the PRO-CTCAE by a group of multidisciplinary investigators and patient representatives and provides an overview of qualitative and quantitative studies of its measurement properties. A systematic evaluation of all 790 AEs listed in the CTCAE identified 78 appropriate for patient self-reporting. For each of these, a PRO-CTCAE plain language term in English and one to three items characterizing the frequency, severity, and/or activity interference of the AE were created, rendering a library of 124 PRO-CTCAE items. These items were refined in a cognitive interviewing study among patients on active cancer treatment with diverse educational, racial, and geographic backgrounds. Favorable measurement properties of the items, including construct validity, reliability, responsiveness, and between-mode equivalence, were determined prospectively in a demographically diverse population of patients receiving treatments for many different tumor types. A software platform was built to administer PRO-CTCAE items to clinical trial participants via the internet or telephone interactive voice response and was refined through usability testing. Work is ongoing to translate the PRO-CTCAE into multiple languages and to determine the optimal approach for integrating the PRO-CTCAE into clinical trial workflow and AE analyses. It is envisioned that the PRO-CTCAE will enhance the precision and patient-centeredness of adverse event reporting in cancer clinical research.
The human gut microbiota impacts host metabolism and has been implicated in the pathophysiology of obesity and metabolic syndromes. However, defining the roles of specific microbial activities and ...metabolites on host phenotypes has proven challenging due to the complexity of the microbiome-host ecosystem. Here, we identify strains from the abundant gut bacterial phylum Bacteroidetes that display selective bile salt hydrolase (BSH) activity. Using isogenic strains of wild-type and BSH-deleted
, we selectively modulated the levels of the bile acid tauro-β-muricholic acid in monocolonized gnotobiotic mice.
BSH mutant-colonized mice displayed altered metabolism, including reduced weight gain and respiratory exchange ratios, as well as transcriptional changes in metabolic, circadian rhythm, and immune pathways in the gut and liver. Our results demonstrate that metabolites generated by a single microbial gene and enzymatic activity can profoundly alter host metabolism and gene expression at local and organism-level scales.
Abstract
The Encyclopedia of DNA Elements (ENCODE) Data Coordinating Center has developed the ENCODE Portal database and website as the source for the data and metadata generated by the ENCODE ...Consortium. Two principles have motivated the design. First, experimental protocols, analytical procedures and the data themselves should be made publicly accessible through a coherent, web-based search and download interface. Second, the same interface should serve carefully curated metadata that record the provenance of the data and justify its interpretation in biological terms. Since its initial release in 2013 and in response to recommendations from consortium members and the wider community of scientists who use the Portal to access ENCODE data, the Portal has been regularly updated to better reflect these design principles. Here we report on these updates, including results from new experiments, uniformly-processed data from other projects, new visualization tools and more comprehensive metadata to describe experiments and analyses. Additionally, the Portal is now home to meta(data) from related projects including Genomics of Gene Regulation, Roadmap Epigenome Project, Model organism ENCODE (modENCODE) and modERN. The Portal now makes available over 13000 datasets and their accompanying metadata and can be accessed at: https://www.encodeproject.org/.
Bariatric surgery, the most effective treatment for obesity and type 2 diabetes, is associated with increased levels of the incretin hormone glucagon-like peptide-1 (GLP-1) and changes in levels of ...circulating bile acids. The levels of individual bile acids in the gastrointestinal (GI) tract after surgery have, however, remained largely unstudied. Using ultra-high performance liquid chromatography-mass spectrometry-based quantification, we observed an increase in an endogenous bile acid, cholic acid-7-sulfate (CA7S), in the GI tract of both mice and humans after sleeve gastrectomy. We show that CA7S is a Takeda G-protein receptor 5 (TGR5) agonist that increases Tgr5 expression and induces GLP-1 secretion. Furthermore, CA7S administration increases glucose tolerance in insulin-resistant mice in a TGR5-dependent manner. CA7S remains gut restricted, minimizing off-target effects previously observed for TGR5 agonists absorbed into the circulation. By studying changes in individual metabolites after surgery, the present study has revealed a naturally occurring TGR5 agonist that exerts systemic glucoregulatory effects while remaining confined to the gut.
The major cell classes of the brain differ in their developmental processes, metabolism, signaling, and function. To better understand the functions and interactions of the cell types that comprise ...these classes, we acutely purified representative populations of neurons, astrocytes, oligodendrocyte precursor cells, newly formed oligodendrocytes, myelinating oligodendrocytes, microglia, endothelial cells, and pericytes from mouse cerebral cortex. We generated a transcriptome database for these eight cell types by RNA sequencing and used a sensitive algorithm to detect alternative splicing events in each cell type. Bioinformatic analyses identified thousands of new cell type-enriched genes and splicing isoforms that will provide novel markers for cell identification, tools for genetic manipulation, and insights into the biology of the brain. For example, our data provide clues as to how neurons and astrocytes differ in their ability to dynamically regulate glycolytic flux and lactate generation attributable to unique splicing of PKM2, the gene encoding the glycolytic enzyme pyruvate kinase. This dataset will provide a powerful new resource for understanding the development and function of the brain. To ensure the widespread distribution of these datasets, we have created a user-friendly website (http://web.stanford.edu/group/barres_lab/brain_rnaseq.html) that provides a platform for analyzing and comparing transciption and alternative splicing profiles for various cell classes in the brain.
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