Race Affects Elastance Responses Following Endurance Exercise Training

The ventricular-vascular coupling ratio is comprised of the ratio of arterial elastance to ventricular elastance. Briefly, arterial elastance (Ea) may be described as total arterial load, and ventricular elastance (Elv) also considers both geometric and physiological variables to quantify left ventricular stiffness. Together, these measures may be indexed to body size (EaI and ElvI) to compile a load-independent portrayal of net cardiac and vascular interaction. Optimal EaI/ElvI results in ideal coronary perfusion and blood distribution to the periphery. Blood pressure (BP) and arterial stiffness are important determinants of EaI/ElvI. African Americans (AA) have consistently been reported to have higher large artery stiffness and BP compared to Caucasian Americans (CA). However, exercise training reduces both BP and large artery stiffness. Our purpose was to determine the effects of race on coupling after an 8 week exercise training intervention. We hypothesized a reduction in the ratio due to a reduction in EaI that would be more pronounced in CA compared to AA adults. We used applanation tonometry to measure central blood pressures and carotid-femoral pulse wave velocity to quantify central arterial stiffness and cardiac ultrasonography to quantify LV volumes before and after our training intervention. We used the formulas: Ea=ESP/SV and Elv=ESP/ESV and divided these numbers by BSA as calculated using Mostellar’s formula. Both AA and CA maintained their pre-training coupling ratios (p>0.05 for time effect and race*time interaction), however, CA did so by uniformly augmenting both EaI and ElvI (Ea was 0.76±0.1 to 0.77±0.09 mmHg/ml/m2 in AA and 0.68±0.09 to 0.75±0.1 mmHg/ml/m2, p=0.02 for CA; ElvI was 1.20±0.11 to 1.22±0.1 mmHg/ml/m2 in AA and 0.99±0.1 to 1.16±0.1 mmHg/ml/m2 in CA p0.05). This occurred despite similar reductions in central arterial stiffness, BP, and ESP in both races. We conclude that, although the coupling ratio was similarly maintained in CA and AA, the responses to training were quite different.published or submitted for publicationis peer reviewe

Effect of acute hypoxemia on cerebral blood flow velocity control during lower body negative pressure.

Contains fulltext : 194624.pdf (publisher's version ) (Open Access

A Hot Saturn Orbiting an Oscillating Late Subgiant Discovered by TESS

We present the discovery of HD 221416 b, the first transiting planet identified by the Transiting Exoplanet Survey Satellite (TESS) for which asteroseismology of the host star is possible. HD 221416 b (HIP 116158, TOI-197) is a bright (V = 8.2 mag), spectroscopically classified subgiant that oscillates with an average frequency of about 430 μHz and displays a clear signature of mixed modes. The oscillation amplitude confirms that the redder TESS bandpass compared to Kepler has a small effect on the oscillations, supporting the expected yield of thousands of solar-like oscillators with TESS 2 minute cadence observations. Asteroseismic modeling yields a robust determination of the host star radius (R∗ = 2.943 ± 0.064 Ro), mass (M∗ = 1.212 ± 0.074 Mo), and age (4.9 ± 1.1 Gyr), and demonstrates that it has just started ascending the red-giant branch. Combining asteroseismology with transit modeling and radial-velocity observations, we show that the planet is a "hot Saturn" (Rp = 9.17 ± 0.33 R⊕) with an orbital period of ∼14.3 days, irradiance of F = 343 ± 24 F⊕, and moderate mass (Mp = 60.5 ± 5.7 M⊕) and density (ρp = 0.431 ± 0.062 g cm-3). The properties of HD 221416 b show that the host-star metallicity-planet mass correlation found in sub-Saturns (4-8 R⊕) does not extend to larger radii, indicating that planets in the transition between sub-Saturns and Jupiters follow a relatively narrow range of densities. With a density measured to ∼15%, HD 221416 b is one of the best characterized Saturn-size planets to date, augmenting the small number of known transiting planets around evolved stars and demonstrating the power of TESS to characterize exoplanets and their host stars using asteroseismology. © 2019. The American Astronomical Society. All rights reserved.