1,574 research outputs found

    Hydrogeochemical Evolution of Groundwaters in the Williston Basin, Canada

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    Glacial cycles over the last two million years have successfully altered deep groundwater flow in the Williston Basin, Canada. Mixing with evaporated paleoseawater has resulted in unique geochemical signatures in formation waters with spatial and temporal trends, however the timing of glaciogenic recharge into the Williston Basin and spatial understanding of the flow system is loosely constrained. I examine timing and effect of glaciogenic recharge by using an integration of fluid chemistry, stable isotope data, and transport modeling. Results demonstrate that meltwater arrived at depths of ~600 to 1000 m in the northcentral region of the Williston Basin at two separate time periods, 75 to 150 ka and 300 ka. Spatial analysis of geochemical data illustrates that meltwater recharge extended to a continuous recharge belt along the northern margin of the Williston Basin, greater than previously anticipated. Individual and multi-variate analysis of isotope and solute geochemistry exhibit trends that contribute to fractionation of δ18O, δ2H, 87Sr/86Sr, δ37Cl, and δ81Br, and validates the importance of water origin and variation in mineral composition on solute concentrations and isotope values. Although overprinting and mixing interactions may present challenges in geochemical interpretation, the inter-disciplinary approach used in this research contributes to a greater understanding of how glacial meltwater recharge altered geochemical landscapes during large-scale salt dissolution in the Williston Basin

    Pro-inflammatory role of monocyte-derived CX3CR1int macrophages in Helicobacter hepaticus-induced colitis

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    Cells of the monocyte-macrophage lineage play important roles in the pathogenesis of inflammatory bowel diseases, but they are also present in the normal healthy intestine, where they are critical for maintaining homeostasis. It has been unclear whether the pro-inflammatory roles of intestinal macrophages reflect altered behaviour of the existing resident cells, or if they involve recruitment of a distinct cell type. Here we have explored these ideas using the model of colitis induced by Helicobacter hepaticus (Hh) in the context of neutralisation or deletion of interleukin 10 (IL-10). Granulocytes and monocytes made up most of the inflammatory myeloid infiltrates found in the colon of Hh-infected colitic mice, rising to a peak within 2 weeks of Hh inoculation, but taking several months to resolve completely. The inflammatory response was dependent on the combined presence of Hh and absence of IL-10, and was accompanied by increased production of inflammatory mediators such as IL-1β, TNFα, IL-6 and IL-23p19 by infiltrating myeloid cells, mostly relatively immature cells of the macrophage lineage that express intermediate levels of CX3CR1. In contrast, the population of mature CX3CR1hi macrophages did not expand as markedly during colitis, and these cells made little contribution to inflammatory mediator production. Taking into account their numerical dominance in the myeloid compartment, we conclude that newly recruited monocytes are the main source of pro-inflammatory mediators in colitis induced in the absence of IL-10 signalling, and that altered behaviour of mature macrophages is not a major component of this pathology

    Blood polymorphonuclear leukocyte chemotaxis during experimental escherichia-coli bovine mastitis.

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    The relationship between the severity of experimental Escherichia coli mastitis and the chemotactic response of blood polymorphonuclear leukocytes was investigated before and during mastitis. Experimental E. coli mastitis was induced in 10 healthy cows by inoculation of the rear right quarters with 10(3) cfu of E. coli. Cows were classified into two groups based on the severity of the mastitis. Bacterial growth in the inoculated quarter was used as parameter that indicated severity. Before and during experimental mastitis, the chemotactic response and the number of circulating polymorphonuclear leukocytes were greater for the moderately diseased cows than for the severely diseased cows. During the first 24 h of the experimental mastitis, the chemotactic response of polymorphonuclear leukocytes decreased in both groups. Recovery of the chemotactic response of white blood cells was more rapid in moderately diseased cows than in severely diseased cows. Possibly, the larger proportion of band neutrophils (the less chemotactically active band neutrophils) partially accounts for the lower chemotactic response of the circulating polymorphonuclear leukocytes during experimental mastitis in the severely diseased cows

    Guardians of the epithelium: macrophages protect against toxic fungal derivatives

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    A recent paper in Cell proposes a new role for macrophages in the distal colonic mucosa, namely the generation of balloon-like processes (BLPs) that sample luminal contents and protect epithelial cells from the toxic effects of fungal metabolites absorbed during this process. Here Allan Mowat and Calum Bain discuss the implications of these novel findings for intestinal physiology and macrophage biology, highlighting how they extend our understanding of how tissue resident macrophages can adapt precisely to the physiological needs of individual anatomical niches

    Diagnostic work-up of patients presenting in primary care with lower abdominal symptoms:which faecal test and triage strategy should be used?

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    Bowel endoscopy referrals from primary care have increased steadily over recent years. However, most patients do not have significant colorectal disease (SCD). Therefore, strategies to select those who would benefit most from endoscopy are of current interest. A recent study developed a multivariable diagnostic model for SCD with routine clinical information, extended with quantitative faecal calprotectin (f-C) point-of-care (POC) testing and/or qualitative POC faecal immunochemical test (FIT) for haemoglobin (f-Hb) results. This study used POC tests for both f-C and f-Hb; however, POC tests have many disadvantages and there are several reasons why quantitative measurements of f-Hb are advantageous. Quantitative faecal immunochemical tests have been used very successfully in triage of patients presenting in primary care as a rule-out test. Studies have compared f-C and f-Hb in this clinical context and consider that f-C is not required in diagnosis. A single quantitative f-Hb result, without any clinical information, could be sufficient to decide whom to refer for endoscopy and, because of the significant overlap of symptoms in those with and without SCD, could be the primary investigation performed. Please see related article: http://bmcmedicine.biomedcentral.com/articles/10.1186/s12916-016-0684-5
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