Sex differences in endothelial function in porcine coronary arteries: a role for H2O2and gap junctions?

BACKGROUND AND PURPOSE: Cardiovascular risk is higher in men and postmenopausal women compared with premenopausal women. This may be due to sex differences in endothelial function. Here, sex differences in endothelial function of porcine coronary arteries (PCAs) were investigated. EXPERIMENTAL APPROACH: Distal PCAs were studied under myographic conditions and after precontraction with U46619. Concentration-response curves to bradykinin were constructed in the presence of a range of inhibitors. KEY RESULTS: In male and female PCAs, bradykinin produced comparable vasorelaxant responses. Inhibition of NO and prostanoid synthesis produced greater inhibition in males compared with females. Removing H2O2 with PEG-catalase reduced the maximum relaxation in the absence, but not the presence of L-NAME and indomethacin in females, and had no effect in males. Blocking gap junctions with 100 muM carbenoxolone or 18α-glycyrrhetinic acid further inhibited the endothelium-derived hyperpolarization (EDH-mediated response in females but not in males. In female PCAs, the maximum EDH-mediated response was reduced by inhibiting SKCa with apamin and by inhibiting IKCa with TRAM-34, or with both. In male PCAs, at maximum bradykinin concentration, the EDH-mediated response was reduced in the presence of apamin but not TRAM-34. Western blot did not detect any differences in connexins 40 or 43 or in IKCa expression between male and female PCAs. CONCLUSIONS AND IMPLICATIONS: H2O2 mediated some part of endothelium-dependent vasorelaxation in female PCAs and EDH was more important in females, with differences in the contribution of gap junctions and IKCa channels. These findings may contribute to understanding vascular protection in premenopausal women

Self-Reported Delays in Care Do not Predict Increased Mortality in a Cohort of Community-Dwelling Elders

Background: Self-reporting of delayed care is a common measure of access to healthcare. The relationship of such reports to worsened health outcomes is often assumed, but few studies have tested this longitudinal connection. Objective: To determine whether self-reports of delayed care predict increased mortality among community-dwelling elderly. Design: 3-year longitudinal retrospective cohort study. Setting: A five county area of North Carolina. Participants: 4,162 randomly sampled individuals age 65 and older. Measurements: The outcome was the proportional hazard ratio (HR) for death stratified by the factor of interest, baseline self-reports of delayed or foregone care. Control variables included predisposing, enabling, and need factors influencing care seeking and/or mortality. Results: Of 3,964 eligible participants reporting, 61% never, 27% once in awhile, and 12% quite often delayed care. 13% of participants died during the study period. Older age, male gender, lower income, less education, lack of supplemental insurance, less social support, more depression, more severe chronic disease, smoking, and worse self-rated health predict increased mortality (pvalues<.0l). Of these, age, lower income, less education, lack of supplemental insurance, less social support, worse self-rated health, and more depression were significantly associated with more self-reported delays in care. In both an unadjusted and fully adjusted survival model, 3-year mortality rates did not differ among cohorts reporting varying degrees of delayed care. Conclusion: Among community dwelling elders, self-reports of delayed care did not predict increased 3-year mortality rates. These results raise questions about self-reporting of delayed or foregone care as a measure of access to the healthcare system.Master of Public Healt

Locally Localized Gravity Models in Higher Dimensions

We explore the possibility of generalizing the locally localized gravity model in five space-time dimensions to arbitrary higher dimensions. In a space-time with negative cosmological constant, there are essentially two kinds of higher-dimensional cousins which not only take an analytic form but also are free from the naked curvature singularity in a whole bulk space-time. One cousin is a trivial extension of five-dimensional model, while the other one is in essence in higher dimensions. One interesting observation is that in the latter model, only anti-de Sitter ($AdS_p$) brane is physically meaningful whereas de Sitter ($dS_p$) and Minkowski ($M_p$) branes are dismissed. Moreover, for $AdS_p$ brane in the latter model, we study the property of localization of various bulk fields on a single brane. In particular, it is shown that the presence of the brane cosmological constant enables bulk gauge field and massless fermions to confine to the brane only by a gravitational interaction. We find a novel relation between mass of brane gauge field and the brane cosmological constant.Comment: 20 pages, LaTex 2e, revised version (to appear in Phys. Rev. D

The Deformable Universe

The concept of smooth deformations of a Riemannian manifolds, recently evidenced by the solution of the Poincar\'e conjecture, is applied to Einstein's gravitational theory and in particular to the standard FLRW cosmology. We present a brief review of the deformation of Riemannian geometry, showing how such deformations can be derived from the Einstein-Hilbert dynamical principle. We show that such deformations of space-times of general relativity produce observable effects that can be measured by four-dimensional observers. In the case of the FLRW cosmology, one such observable effect is shown to be consistent with the accelerated expansion of the universe.Comment: 20 pages, LaTeX, 3 figure

Localization of gravity in brane world with arbitrary extra dimensions

We study the induced 4-dimensional linearized Einstein field equations in an m-dimensional bulk space by means of a confining potential. It is shown that in this approach the mass of graviton is quantized. The cosmological constant problem is also addressed within the context of this approach. We show that the difference between the values of the cosmological constant in particle physics and cosmology stems from our measurements in two different scales, small and large.Comment: 8 pages. arXiv admin note: substantial text overlap with arXiv:gr-qc/0408004, arXiv:gr-qc/0607067, arXiv:0704.1035, arXiv:0707.3558, arXiv:0710.266

Geometry of Brane-Worlds

The most general geometrical scenario in which the brane-world program can be implemented is investigated. The basic requirement is that it should be consistent with the confinement of gauge interaction, the existence of quantum states and the embedding in a bulk with arbitrary dimensions, signature and topology. It is found that the embedding equations are compatible with a wide class of Lagrangians, starting with a modified Einstein-Hilbert Lagrangian as the simplest one, provided minimal boundaries are added to the bulk. A non-trivial canonical structure is derived, suggesting a canonical quantization of the brane-world geometry relative to the extra dimensions, where the quantum states are set in correspondence with high frequency gravitational waves. It is shown that in the cases of at least six dimensions, there exists a confined gauge field included in the embedding structure. The size of extra dimensions compatible with the embedding is calculated and found to be different from the one derived with product topology.Comment: Minor changes and a correction to equation (22). 9 pages twocolumn Revte