Advanced Colloids Experiment (Temperature Controlled) - ACE-T2

Increment 57 - 58 Science Symposium presentation of Advanced Colloids Experiment (ACE-T2) to RPO. The purpose of this event is for Principal Investigators to present their science objectives, testing approach, and measurement methods to agency scientists, managers, and other investigators

Differential responses to vitamin D2 and vitamin d3 are associated with variations in free 25-hydroxyvitamin D

25-Hydroxyvitamin D (25D) circulates bound primarily to serum vitamin D binding protein (DBP), with DBP showing higher binding affinity for 25D3 than 25D2. We therefore hypothesized that vitamin D2 (D2) promotes higher serum levels of unbound 25D (free 25D), with different functional responses, relative to vitamin D3 (D3). Week 3 C56BL/6 mice were placed on diets containing either D2 or D3 alone (both 1000 IU/kg). At week 8 and week 16, D2 mice had only 25D2 in circulation (26.6 ± 1.9 and 33.3 ± 4.4 ng/mL), and D3 mice had only 25D3 (28.3 ± 2.0 and 31.7 ± 2.1 ng/mL). At week 8 (44.5 ± 6.4 vs 62.4 ± 11.6 pg/mL, P < .05) and week 16 (78.4 ± 12.6 vs 95.5 ± 11.6), D2 mice had lower serum 1,25-dihydroxyvitamin D relative to D3 mice. By contrast, measured free 25D was significantly higher in D2 mice at week 8 (16.8 ± 0.65 vs 8.4 ± 0.63 pg/mL, P < .001) and week 16 (17.4 ± 0.43 vs 8.4 ± 0.44, P < .001). A two-way ANOVA of bone histomorphometry showed that week 8 D2 mice had significantly higher osteoclast surface/bone surface, eroded surface/bone surface, and mineral apposition rate compared with D3 mice. Osteoblast surface/bone surface was higher in week 8 D2 females but not week 8 D2 males. At week 16, D2 mice had significantly higher bone volume/total volume and trabecular number compared with D3 mice. Differences in bone phenotype were observed despite D2 mice reaching similar serum 25D levels and lower 1,25D levels compared with D3 mice. These data indicate that 25D2 binds less well to DBP than 25D3, with resulting higher levels of free 25D promoting differential effects on bone in mice exposed to D2 alone

Acute hypoxic exercise does not alter post-exercise iron metabolism in moderately trained endurance athletes

Item does not contain fulltextPURPOSE: This study measured the influence of acute hypoxic exercise on Interleukin-6 (IL-6), hepcidin, and iron biomarkers in athletes. METHODS: In a repeated measures design, 13 moderately trained endurance athletes performed 5 x 4 min intervals at 90 % of their peak oxygen consumption velocity (vVO2peak) in both normoxic [NORM, fraction of inspired oxygen (F IO2) = 0.2093, 15.3 +/- 1.7 km h(-1)] and simulated hypoxic (HYP, F IO2 = 0.1450, 13.2 +/- 1.5 km h(-1)) conditions. Venous blood samples were obtained pre-, post-, and 3 h post-exercise, and analysed for serum hepcidin, IL-6, ferritin, iron, soluble transferrin receptor (sTfR), and transferrin saturation. RESULTS: Peak heart rate was significantly lower in HYP compared with NORM (p = 0.01); however, the rating of perceived exertion was similar between trials (p = 0.24). Ferritin (p = 0.02), transferrin (p = 0.03), and IL-6 (p = 0.01) significantly increased immediately post-exercise in both conditions, but returned to baseline 3 h later. Hepcidin levels significantly increased in both conditions 3 h post-exercise (p = 0.05), with no significant differences between trials. A significant treatment effect was observed between trials for sTfR (p = 0.01), but not iron and transferrin saturation. CONCLUSION: Acute exercise in hypoxia did not influence post-exercise IL-6 production, hepcidin activity or iron metabolism compared with exercise at the same relative intensity in normoxia. Hence, acute exercise performed at the same relative intensity in hypoxia poses no further risk to an athlete's iron status, as compared with exercise in normoxia

Jump-Bidding Strategies in Internet Auctions

A bidding strategy commonly observed in Internet auctions is that of jump-bidding, or entering a bid larger than what is necessary to be a currently winning bidder. In this paper, we argue that the cost associated with entering on-line bids and the uncertainty about future entry both of which distinguish Internet from live auctions can explain this phenomenon. We present a simple theoretical model that accounts for the preceding characteristics, and derive the conditions under which jump-bidding strategies arise in a format commonly used for on-line trading, the ascending-price auction. We also present evidence recorded from hundreds of Internet auctions that is consistent with the basic predictions from our model. We find that jump-bidding is more likely earlier in an Internet auction, when jumping has a larger strategic value, and that the incentives to jump bid increase as bidder competition becomes stronger. Our results also indicate that jump bidding is effective: jump bidders place fewer bids overall, and increased early jump bidding in auctions reduces the total bids placed. We also discuss possible means of reducing bidding costs, and evidence that Internet auctioneers are pursuing this goal. 1