Cumming School of Medicine
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The University of Calgary Faculty of Medicine was established in 1967 and renamed the Cumming School of Medicine in 2014. The Cumming School of Medicine is a national research leader in brain and mental health, chronic diseases and cardiovascular sciences.
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Browsing Cumming School of Medicine by Department "Biological Science"
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Item Embargo Anti-inflammatory effects of retinoids and carotenoid derivatives on caspase-3–dependent apoptosis and efferocytosis of bovine neutrophils(American Journal of Veterinary Research, 2014-12) Duquette, Stephanie C.; Fischer, Carrie D.; Feener, Troy D.; Muench, Gregory P.; Morck, Douglas W.; Barreda, Daniel R.; Nickerson, James G.; Buret, Andre G.Objective—To evaluate immunomodulatory properties of all-trans retinoic acid and a fully oxidized β-carotene dietary product in calves with Mannheimia haemolytica–induced pneumonia. Animals—Twenty-five 6- to 10-week-old male Holstein calves for experimental inoculations and three 8- to 30-week-old Angus heifers for blood donations. Procedures—In vitro, neutrophils and monocyte-derived macrophages isolated from blood of healthy Angus heifers were treated with all-trans retinoic acid (1μM) or fully oxidized β-carotene (8.3 μg/mL) for various times and assessed for markers of cellular death, antimicrobial function, and production of proinflammatory leukotriene B4. Following 28 days of dietary supplementation with fully oxidized β-carotene, Holstein calves were experimentally inoculated with M haemolytica. Bronchoalveolar lavage fluid was collected at 3 and 24 hours after challenge inoculation and analyzed for markers of apoptosis. Results—In vitro, all-trans retinoic acid and fully oxidized β-carotene induced cell-selective, caspase-3–dependent apoptosis in neutrophils, which subsequently enhanced efferocytosis in macrophages. Conversely, neither treatment altered phorbol 12-myristate 13-acetate–induced oxidative burst, phagocytosis of nonopsonized zymosan (complement or antibody independent), or M haemolytica–induced leukotriene B4 production in bovine neutrophils. In vivo, fully oxidized β-carotene enhanced leukocyte apoptosis in bronchoalveolar lavage fluid as well as subsequent efferocytosis by macrophages without altering numbers of circulating leukocytes. Conclusions and Clinical Relevance—Neutrophil apoptosis and subsequent efferocytosis by macrophages are key mechanisms in the resolution of inflammation. Findings for the present study indicated that all-trans retinoic acid and fully oxidized β-carotene could be novel nutraceutical strategies that may confer anti-inflammatory benefits for cattle with respiratory tract disease.Item Embargo Giardia duodenalis: New Research Developments in Pathophysiology, Pathogenesis, and Virulence Factors(Current Tropical Medicine Reports, 2015-07-11) Buret, Andre G.; Amat, Christina B.; Manko, Anna; Beatty, Jennifer K.; Halliez, Marie C. M.; Bhargava, Amol; Motta, Jean-Paul; Cotton, James A.Giardia duodenalis is a very common, ubiquitous, intestinal protozoan parasite infecting animals and humans. Of the eight distinct genetic assemblages known to date, assemblages A and B are infectious to humans. Giardia is the most commonly recognized cause of traveller’s diarrhea. Giardiasis impairs weight gain and is responsible for a variety of extra-intestinal and post-infectious complications, including post-infectious irritable bowel syndrome, chronic fatigue, failure to thrive, and cognitive impairment. Giardiasis occurs in the absence of invasion of the intestinal tissues by the trophozoites and in the absence of any overt inflammatory cell infiltration, with the exception of a modest increase in intraepithelial lymphocytes and mast cells. In endemic parts of the World where the infection is often concurrent with bacterial enteritis causing inflammation-driven diarrheal disease, giardiasis appears to be protective against diarrhea. Recent observations have demonstrated that this effect may be due to a direct immuno-modulating effect of the parasite via its cathepsin B cysteine protease which cleaves pro-inflammatory CXCL8. No known toxin has yet been directly implicated in the pathophysiology of giardiasis. Diarrhea in giardiasis is mostly malabsorptive in nature, rather than hypersecretory. Findings from ongoing research indicate that the post-infectious effects of giardiasis may be due to microbiota dysbiosis induced by the parasite during the acute phase of infection.