56 research outputs found

    Hemopoiesis in the Thymus

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    The presence in the thymus of hemopoietic cells other than thymocytes has been known for many years, but the extent of the hemopoietic activity of the thymus and the possible functional implications have only recently begun to receive much attention. This review summarizes the literature in this field, especially in the light of current cytokine and thymic-factor knowledge, and includes clinical relevance where possible

    Author's Corrigendum: Hemopoiesis in the Thymus

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    Elemental Levels in Mast Cell Granules Differ in Sections From Normal and Diabetic Rats: An X-Ray Microanalysis Study

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    Mast cells around the thymus of rats stain red with alcian blue and safranin indicating that the mast cells are probably of the peritoneal (connective tissue) type. After the onset of streptozotocin induced diabetes some cells contain both red and blue granules and blue staining cells may appear. X-ray microanalysis of frozen freeze-dried sections from diabetic male CSE Wistar rats showed electron dense granules to have similar amounts of S to normal rat mast cell granules but reduced levels of Na, Mg, P, Cl and K. Two cells also had electron lucent granules with very high levels of Na, Cl, K and Ca and reduced concentrations of S. The differences in elemental composition suggest that the mast cells from diabetic rats are not immature, but are related to the condition of induced diabetes, and that granules of very different composition can occur within a single cell. X-ray microanalysis has given an insight into mast cell granule elemental content which was not possible by conventional biochemical methods

    Rapid progesterone actions on thymulin-secreting epithelial cells cultured from rat thymus

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    Many soluble factors of neural, endocrine, paracrine and autocrine origin are present in the thymus and modulate its function. Long-term effects of sex steroids have! been documented for thymocytes and cells of the thymic microenvironment. In this report we examine rapid actions of progesterone upon aspects of epithelial cell physiology. Progesterone (0.1-10 mu M) was applied to cultured thymulin-secreting thymic epithelial cells (TS-TEC) and changes in transmembrane potential, transmembrane current, intracellular calcium levels and thymulin secretion were assessed. Rapid changes in electrophysiology and intracellular calcium provide evidence for a membrane-bound progesterone receptor in these cells, in addition to classical cytoplasmic receptors. Application of progesterone to TS-TEC caused electrophysiological changes in 56% of cells (n = 40), activating an inward current (-24 +/- 9 pA at 1 mu M, n = 7, p < 0.02) and dose-dependent depolarization (7.1 +/- 1.8 mV at 1 mu M, n = 19, p < 0.01). Intracellular calcium levels, monitored by the ratiometric fluorescent calcium indicator fura-2, increased within seconds of progesterone (1 mu M) application. Progesterone(1 mu M) increased thymulin levels in supernatant, as measured by ELISA, above the levels in the preapplication period (142 +/- 16% of the preapplication period, n = 3, p < 0.02). This effect was reduced in the presence of cobalt chloride which blocks voltage-dependent calcium channels. In addition, TS-IEC in culture were immunoreactive to antibody AG7. This antibody was raised to a membrane-bound antigen involved in calcium influx subsequent to progesterone binding in sperm. thus we suggest that progesterone acts upon many aspects of TS-TEC physiology through both cytoplasmic and membrane-bound receptors

    Neuropeptides Exert Direct Effects on Rat Thymic Epithelial Cells in Culture

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    To determine if major thymic neuropeptides and neurotransmitters can directly influence the functional activity of cultured rat thymic epithelium, neuropeptides and neurotransmitters were applied, and intercellular communication, proliferation, and thymulin secretion assessed. After injections of a mixture of lucifer yellow dextran (too large to pass gap junctions) and cascade blue (which does) into single cells, some neuropeptides decrease dye coupling: 0.1 mM GABA (P < 0.0001), 100 nM NPY (P < 0.0001), 100 nM VIP (P < 0.001), 100 nM CGRP (P < 0.001), 100 nM SP (P < 0.01), and 0.1 mM histamine (P < 0.01), whereas 0.1 mM 5-HT, mM acetylcholine, and 1 μM isoproterenol (β-adrenergic agonist) had no effect. Proliferation (incorporation of tritiated thymidine) was increased by CGRP (P = 0.004) and histamine (P < 0.02), but decreased by isoproterenol (P = 0.002), 5-HT (P = 0.003), and acetylcholine (P < 0.05). The percentage of multinucleate cells was decreased after isoproterenol (2.5%), and increased after 5-HT (21.3%), GABA (15%), and histamine (15.1%). Compared to controls, thymulin in the supernatant was decreased after challenge with acetylcholine (52%), isoproterenol (71%), 5-HT (73%), and histamine (84%). This study demonstrates direct effects of neuropeptides and neurotransmitters on functional aspects of cultured thymic epithelial cells

    How embedded is public involvement in mainstream health research in England a decade after policy implementation? A realist evaluation

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    Objectives: To explore how embedded patient and public involvement (PPI) is within mainstream health research following two decades of policy-driven work to underpin health research with PPI in England. Methods: Realist evaluation using Normalization Process Theory as a programme theory to understand what enabled PPI to be embedded as normal practice. Data was collected through a national scoping and survey, and qualitative methods to track PPI processes and impact over time within 22 nationally funded research projects. Results: In research studies that were able to create reciprocal working relationships and to embed PPI this was contingent on: the purpose of PPI being clear; public contributors reflecting research end-beneficiaries; researchers understanding the value of PPI; PPI opportunities being provided throughout the research; and ongoing evaluation of PPI. Key contested areas included: whether to measure PPI impact; seeking public contributors to maintain a balance between being research-aware and an outsider standpoint seen as ‘authentically’ lay; scaling-up PPI embedded within a research infrastructure rather than risk token presence ; and whether PPI can have a place within basic science. Conclusion: While PPI can be well-integrated within all types of research, policy makers should take account of tensions that must be navigated in balancing the moral and methodological imperatives

    Federated learning enables big data for rare cancer boundary detection.

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    Although machine learning (ML) has shown promise across disciplines, out-of-sample generalizability is concerning. This is currently addressed by sharing multi-site data, but such centralization is challenging/infeasible to scale due to various limitations. Federated ML (FL) provides an alternative paradigm for accurate and generalizable ML, by only sharing numerical model updates. Here we present the largest FL study to-date, involving data from 71 sites across 6 continents, to generate an automatic tumor boundary detector for the rare disease of glioblastoma, reporting the largest such dataset in the literature (n = 6, 314). We demonstrate a 33% delineation improvement for the surgically targetable tumor, and 23% for the complete tumor extent, over a publicly trained model. We anticipate our study to: 1) enable more healthcare studies informed by large diverse data, ensuring meaningful results for rare diseases and underrepresented populations, 2) facilitate further analyses for glioblastoma by releasing our consensus model, and 3) demonstrate the FL effectiveness at such scale and task-complexity as a paradigm shift for multi-site collaborations, alleviating the need for data-sharing

    Author Correction: Federated learning enables big data for rare cancer boundary detection.

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    10.1038/s41467-023-36188-7NATURE COMMUNICATIONS14

    Search for gravitational-lensing signatures in the full third observing run of the LIGO-Virgo network

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    Gravitational lensing by massive objects along the line of sight to the source causes distortions of gravitational wave-signals; such distortions may reveal information about fundamental physics, cosmology and astrophysics. In this work, we have extended the search for lensing signatures to all binary black hole events from the third observing run of the LIGO--Virgo network. We search for repeated signals from strong lensing by 1) performing targeted searches for subthreshold signals, 2) calculating the degree of overlap amongst the intrinsic parameters and sky location of pairs of signals, 3) comparing the similarities of the spectrograms amongst pairs of signals, and 4) performing dual-signal Bayesian analysis that takes into account selection effects and astrophysical knowledge. We also search for distortions to the gravitational waveform caused by 1) frequency-independent phase shifts in strongly lensed images, and 2) frequency-dependent modulation of the amplitude and phase due to point masses. None of these searches yields significant evidence for lensing. Finally, we use the non-detection of gravitational-wave lensing to constrain the lensing rate based on the latest merger-rate estimates and the fraction of dark matter composed of compact objects
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