Person:

Zhang, Peng

Cardiac hypertrophy is a well-established risk factor for cardiovascular morbidity and mortality. Activation of (G_{q/11})-mediated signaling is required for pressure overload-induced cardiomyocyte (CM) hypertrophy to develop. We previously showed that among Regulators of G protein Signaling, RGS2 selectively inhibits (G_{q/11}) signaling and its hypertrophic effects in isolated CM. In this study, we generated transgenic mice with CM-specific, conditional RGS2 expression (dTG) to investigate whether RGS2 overexpression can be used to attenuate (G_{q/11})-mediated signaling and hypertrophy in vivo. Transverse aortic constriction (TAC) induced a comparable rise in ventricular mass and ANF expression and corresponding hemodynamic changes in dTG compared to wild types (WT), regardless of the TAC duration (1-8 wks) and timing of RGS2 expression (from birth or adulthood). Inhibition of endothelin-1-induced (G_{q/11})-mediated phospholipase C β activity in ventricles and atrial appendages indicated functionality of transgenic RGS2. However, the inhibitory effect of transgenic RGS2 on (G_{q/11})-mediated PLCβ activation differed between ventricles and atria: (i) in sham-operated dTG mice the magnitude of the inhibitory effect was less pronounced in ventricles than in atria, and (ii) after TAC, negative regulation of (G_{q/11}) signaling was absent in ventricles but fully preserved in atria. Neither difference could be explained by differences in expression levels, including marked RGS2 downregulation after TAC in left ventricle and atrium. Counter-regulatory changes in other (G_{q/11})-regulating RGS proteins (RGS4, RGS5, RGS6) and random insertion were also excluded as potential causes. Taken together, despite ample evidence for a role of RGS2 in negatively regulating (G_{q/11}) signaling and hypertrophy in CM, CM-specific RGS2 overexpression in transgenic mice in vivo did not lead to attenuate ventricular (G_{q/11})-mediated signaling and hypertrophy in response to pressure overload. Furthermore, our study suggests chamber-specific differences in the regulation of RGS2 functionality and potential future utility of the new transgenic model in mitigating (G_{q/11}) signaling in the atria in vivo.

We predict that a large class of helium-containing cold polar molecules form readily in a cryogenic buffer gas, achieving densities as high as 10(^{12})  cm(^{-3}). We explore the spin relaxation of these molecules in buffer-gas-loaded magnetic traps and identify a loss mechanism based on Landau-Zener transitions arising from the anisotropic hyperfine interaction. Our results show that the recently observed strong (T^{-6}) thermal dependence of the spin-change rate of silver (Ag) trapped in dense (^{3})He is accounted for by the formation and spin change of Ag(^{3})He van der Waals molecules, thus providing indirect evidence for molecular formation in a buffer-gas trap.

Multireference configuration interaction and coupled cluster calculations have been carried out to determine the potential energy curves for the ground and low-lying excited states of the LiYb molecule. The scalar relativistic effects have been included by means of the Douglas–Kroll Hamiltonian and effective core potential and the spin-orbit couplings have been evaluated by the full microscopic Breit–Pauli operator. The LiYb permanent dipole moment, static dipole polarizability, and Franck–Condon factors have been determined. Perturbations of the vibrational spectrum due to nonadiabatic interactions are discussed.

We use accurate ab initio and quantum scattering calculations to demonstrate that the maximum He3 spin polarization that can be achieved in spin-exchange collisions with potassium (K39) and silver (Ag107) atoms is limited by the anisotropic hyperfine interaction. We find that spin exchange in Ag-He collisions occurs much faster than in K-He collisions over a wide range of temperatures (10–600 K). Our analysis indicates that measurements of trap loss rates of S2 atoms in the presence of cold He3 gas may be used to probe anisotropic spin-dependent interactions in atom-He collisions.

[1] Accurate data on energy-transfer collisions between hot oxygen atoms and the atmospheric helium gas on Mars, are reported. Anisotropic cross sections for elastic collisions of O(3P) and O(1D) atoms with helium gas have been calculated quantum mechanically and found to be surprisingly similar. Cross sections, computed for collisions with both helium isotopes, 3He and 4He, have been used to construct the kernel of the Boltzmann equation describing the energy relaxation of hot oxygen atoms. Computed rates of energy transfer in O+He collisions have been used to evaluate the flux of He atoms escaping from the Mars atmosphere. Atmospheric layers mostly responsible for production of the He escape flux are identified. Our results demonstrate that strong angular anisotropy of scattering cross sections increases the collisional ejection of light atoms and is critical in the evaluation of He escape from Mars, Venus and Earth.

Background: The prevalence of metabolic syndrome (MetS) is growing rapidly in China. Tai chi and dancing are common types of exercise among middle-aged and elderly Chinese. It remains unclear whether these activities are associated with a lower risk of MetS. Methodology/Principal Findings A total of 15,514 individuals (6,952 men, 8,562 women) aged 50 to 70 years from the Dongfeng-Tongji Cohort in Shiyan, China participated in a cross-sectional study. Physical activity and other lifestyle factors were assessed with semi-structured questionnaires during face-to-face interviews. MetS was defined by the current National Cholesterol Education Program/Adult treatment Panel III criteria for Asian Americans. The prevalence of MetS was 33.2% in the study population. In the multivariable-adjusted logistic regression analyses, total physical activity levels were monotonically associated with a lower odds of MetS [OR 0.75 comparing extreme quintiles, 95% confidence interval (CI) 0.66–0.86, P<0.001]. Compared with non-exercisers in a specific exercise type, jogging (OR 0.82, 95% CI 0.68–1.00, P = 0.046), tai chi (OR 0.72, 95% CI 0.60–0.88, P<0.001), and dancing (OR 0.56, 95% CI 0.47–0.67, P<0.001) were associated with significantly lower odds of MetS. Furthermore, each 1–h/week increment in tai chi and dancing was associated with a 5% (95% CI 2%–9%) and a 9% (95% CI 6%, 12%) lower risk of MetS. Conclusions/Significance: Jogging, tai chi and dancing are associated with a significantly lower risk of having MetS in middle-aged and older Chinese. Future intervention studies should consider the role of jogging, tai chi and dancing in preventing MetS.

We present a quantal study of the rotationally elastic and inelastic scattering of Ag and N(2), with the nitrogen molecule treated as a rigid rotor. The two-dimensional potential energy surface of the AgN(2) complex is obtained ab initio by means of the spin unrestricted coupled-cluster method with single, double, and perturbative triple excitations. The global minimum is found to be located at an internuclear distance of 8.13 a(0) and an angle of 127.2°. The long-range part of the potential is constructed from the dynamic electric dipole polarizabilities of Ag and N(2). Elastic, excitation, and relaxation cross sections and rates are calculated for energies between 0.1 and 5000 cm(-1). The momentum transfer cross sections and rates are also computed. Finally, we compare the cross sections for Ag-N(2) and Na-N(2) to explore the possibility of using silver instead of sodium in experimental tests.