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See detailThe yellow hypergiant HR 5171 A: Resolving a massive interacting binary in the common envelope phase
Chesneau, O.; Meilland, A.; Chapellier, E. et al

in Astronomy and Astrophysics (2014), 563

Context. Only a few stars are caught in the very brief and often crucial stages when they quickly traverse the Hertzsprung-Russell diagram, and none has yet been spatially resolved in the mass transfer ... [more ▼]

Context. Only a few stars are caught in the very brief and often crucial stages when they quickly traverse the Hertzsprung-Russell diagram, and none has yet been spatially resolved in the mass transfer phase. Aims: We initiated long-term optical interferometry monitoring of the diameters of massive and unstable yellow hypergiants (YHG) with the goal of detecting both the long-term evolution of their radius and shorter term formation of a possible pseudo-photosphere related to proposed large mass-loss events. Methods: We observed HR 5171 A with AMBER/VLTI. We also examined archival photometric data in the visual and near-IR spanning more than 60 years, as well as sparse spectroscopic data. Results: HR 5171 Aexhibits a complex appearance. Our AMBER data reveal a surprisingly large star for a YHG R∗ = 1315 ± 260R⊙ (or ~6.1 AU) at the distance of 3.6 ± 0.5 kpc. The source is surrounded by an extended nebulosity, and these data also show a large level of asymmetry in the brightness distribution of the system, which we attribute to a newly discovered companion star located in front of the primary star. The companion's signature is also detected in the visual photometry, which indicates an orbital period of Porb = 1304 ± 6 d. Modeling the light curve with the NIGHTFALL program provides clear evidence that the system is a contact or possibly over-contact eclipsing binary. A total current system mass of 39^+40_-22 M⊙ and a high mass ratio q ≥ 10 is inferred for the system. Conclusions: The low-mass companion of HR 5171 is very close to the primary star that is embedded within its dense wind. Tight constraints on the inclination and vsini of the primary are lacking, which prevents us from determining its influence precisely on the mass-loss phenomenon, but the system is probably experiencing a wind Roche-Lobe overflow. Depending on the amount of angular momentum that can be transferred to the stellar envelope, HR 5171 A may become a fast-rotating B[e]/luminous blue variable/Wolf-Rayet star. In any case, HR 5171 A highlights the possible importance of binaries for interpreting the unstable YHGs and for massive star evolution in general. [less ▲]

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See detailSubstance 101333-3 reduces pulmonary oxidative stress in cadmium-exposed rats
Kirschvink, Nathalie; Fievez, Laurence ULg; Marlin, D. et al

in European Respiratory Journal (2005), 104s

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See detailTheophylline increases glutathione in BAL of cadmium-exposed rats
Kirschvink, Nathalie; Fievez, Laurence ULg; Desmet, C. et al

in Proceedings of the American Thoracic Society, San Diego, California (2005)

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See detailCadmium-induced oxidative stress and lung emphysema in rats
Kirschvink, Nathalie; Delvaux, F.; Vincke, G. et al

in Prostaglandins, Leukotrienes, and Essential Fatty Acids (2004), 71

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See detailRelationship between markers of blood oxidant status and physiological variables in healthy and heaves-affected horses after exercise
Kirschvink, Nathalie; Art, Tatiana ULg; de Moffarts, Brieuc et al

in Equine Veterinary Journal. Supplement (2002), 34

Exercise-induced oxidative stress is investigated as a potential performance-limiting factor in human sports medicine. Therefore, the present study aimed to assess whether physiological variables that ... [more ▼]

Exercise-induced oxidative stress is investigated as a potential performance-limiting factor in human sports medicine. Therefore, the present study aimed to assess whether physiological variables that change with exercise intensity were correlated with blood oxidant markers in healthy and heaves-affected horses. Seven healthy horses, 8 heaves-affected in remission and 7 heaves-affected in crisis performed a standardised exercise test (SET) of stepwise increasing intensity. Variables monitored during exercise were heart rate (HR), venous plasma lactate (LA), packed cell volume (PCV) and arterial oxygen tension (PaO2). Oxidant markers (uric acid [UA], 8-iso-PGF2alpha and reduced [GSH] and oxidised glutathione [GSSG]) were analysed in venous peripheral blood sampled at rest (R), at peak-exercise intensity (Emax), 15 (E15) and 60 (E60) min after SET. There was a significant effect of heaves on oxidant markers and, therefore, correlation analyses between physiological variables and oxidant markers were performed separately per horse group. In healthy horses, UA analysed at Emax was positively correlated with LA. Furthermore, GSH analysed at Emax and E15 was positively correlated with PaO2. In healthy and heaves-affected horses in remission, GSH and GSSG determined at Emax were negatively correlated with HR. There was no significant correlation between 8-iso-PGF2alpha and physiological variables. In conclusion, a correlation between the physiological response to exercise and some oxidant markers exists in healthy horses. However, in heaves-affected horses the blood oxidant status is probably more dependant on airway disease than on exercise. Future studies should be undertaken to assess whether antioxidant supplementation might positively influence the oxidant-antiodidant balance in exercising horses. [less ▲]

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See detailCorrelation between exercise parameters and oxidant markers in horses
Kirschvink, Nathalie; Art, Tatiana ULg; De Moffarts, Brieux et al

in Pflügers Archiv : European Journal of Physiology (2002), 443

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See detailEffect of nutritional antioxidant supplementation on systemic and pulmonary antioxidant status, airway inflammation and lung function in heaves-affected horses
Kirschvink, Nathalie; Fievez, Laurence ULg; Bougnet, V. et al

in Equine Veterinary Journal (2002), 34

An oxidant/antioxidant imbalance in favour of oxidants has been identified as playing a decisive role in the pathogenesis of chronic inflammatory airway diseases. Nutritional antioxidant supplementation ... [more ▼]

An oxidant/antioxidant imbalance in favour of oxidants has been identified as playing a decisive role in the pathogenesis of chronic inflammatory airway diseases. Nutritional antioxidant supplementation might reduce oxidative damage by enhancement of the antioxidant defence, thereby modulating inflammatory processes. In a placebo-controlled, blind study, it was tested whether a dietary antioxidant supplement administered for 4 weeks would improve lung function and reduce airway inflammation in heaves-affected horses. Eight horses in clinical remission of heaves were investigated at rest and after a standardised exercise test before and after treatment with an antioxidant supplement (consisting of a mixture of natural antioxidants including vitamins E and C and selenium from a variety of sources) or placebo (oatfeed pellets without additive). Pulmonary function and exercise tolerance were monitored; systemic and pulmonary lining fluid uric acid, glutathione and 8-epi-PGF(2alpha) were analysed, and bronchoalveolar lavage (BAL) cytology and inflammatory scoring of the airways were performed. The antioxidant treatment significantly improved exercise tolerance and significantly reduced endoscopic inflammatory score. Plasma uric acid concentrations were significantly reduced, suggesting downregulation of the xanthine-dehydrogenase and xanthine-oxydase pathway. Haemolysate glutathione showed a nonsignificant trend to increase, while plasma 8-epi-PGF(2alpha) remained unchanged. Pulmonary markers and BAL cytology were not significantly affected by antioxidant supplementation. The present study suggests that the antioxidant supplement tested modulated oxidant/antioxidant balance and airway inflammation of heaves-affected horses [less ▲]

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See detailEffect of chronic airway inflammation and exercise on pulmonary and systemic antioxidant status of healthy and heaves-affected horses
Kirschvink, Nathalie; Smith, N.; Fievez, Laurence ULg et al

in Equine Veterinary Journal (2002), 34(6), 563-571

In heaves-affected horses the relation between oxidant status, airway inflammation (AI) and pulmonary function (PF) is unknown. The oxidant status of blood and pulmonary epithelial lining fluid (PELF) of ... [more ▼]

In heaves-affected horses the relation between oxidant status, airway inflammation (AI) and pulmonary function (PF) is unknown. The oxidant status of blood and pulmonary epithelial lining fluid (PELF) of healthy (H, n = 6) and heaves-affected horses in clinical remission (REM, n = 6) and in crisis (CR, n = 7) was assessed at rest, during and after standardised exercise test by measurement of reduced and oxidised glutathione, glutathione redox ratio [GRR%]; uric acid and 8-epi-PGF2alpha. Oxidant status was related to PF parameters (mechanics of breathing and arterial blood gas tension) and Al parameters (bronchoalveolar lavage [BAL] neutrophil % and AI score). Haemolysate glutathione was significantly different between groups and was correlated with PF and AI parameters; GRR in PELF was increased during CR and was correlated with PF and AI parameters. Exercise induced an increase of plasma uric acid that was significantly higher both in REM and CR. PELF 8-epi-PGF2alpha was significantly increased in CR and correlated with PF and AI parameters. These results suggest that oxidative stress occurring in heaves is correlated with PF and AI and may be locally assessed by PELF glutathione status, uric acid and 8-epi-PGF2alpha. Systemic repercussions are reflected by assay of GSH in resting horses and by uric acid in exercising horses. [less ▲]

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See detailEffect of crisis of recurrent airway obstruction on indices of oxidative stress in the bronchoalveolar lavage of horses
Art, Tatiana ULg; Kirschvink, Nathalie; Smith, N. et al

in Pflügers Archiv : European Journal of Physiology (1998)

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