663 research outputs found
Endothelial cells, endoplasmic reticulum stress and oxysterols
Oxysterols are bioactive lipids that act as regulators of lipid metabolism, inflammation, cell viability and are involved in several diseases, including atherosclerosis. Mounting evidence linked the atherosclerosis to endothelium dysfunction; in fact, the endothelium regulates the vascular system with roles in processes such as hemostasis, cell cholesterol, hormone trafficking, signal transduction and inflammation. Several papers shed light the ability of oxysterols to induce apoptosis in different cell lines including endothelial cells. Apoptotic endothelial cell and endothelial denudation may constitute a critical step in the transition to plaque erosion and vessel thrombosis, so preventing the endothelial damaged has garnered considerable attention as a novel means of treating atherosclerosis. Endoplasmic reticulum (ER) is the site where the proteins are synthetized and folded and is necessary for most cellular activity; perturbations of ER homeostasis leads to a condition known as endoplasmic reticulum stress. This condition evokes the unfolded protein response (UPR) an adaptive pathway that aims to restore ER homeostasis. Mounting evidence suggests that chronic activation of UPR leads to cell dysfunction and death and recently has been implicated in pathogenesis of endothelial dysfunction. Autophagy is an essential catabolic mechanism that delivers misfolded proteins and damaged organelles to the lysosome for degradation, maintaining basal levels of autophagic activity it is critical for cell survival. Several evidence suggests that persistent ER stress often results in stimulation of autophagic activities, likely as a compensatory mechanism to relieve ER stress and consequently cell death. In this review, we summarize evidence for the effect of oxysterols on endothelial cells, especially focusing on oxysterols-mediated induction of endoplasmic reticulum stress
A Novel System for Identification of Inhibitors of Rift Valley Fever Virus Replication
Rift Valley fever virus (RVFV) is a human and livestock pathogen endemic to sub-Saharan Africa. We have developed a T7-dependent system for the efficient production of RVFV-like particles (RVF-VLPs) based on the virulent ZH-501 strain of RVFV. The RVF-VLPs are capable of performing a single round of infection, allowing for the study of viral replication, assembly, and infectivity. We demonstrate that these RVF-VLPs are antigenically indistinguishable from authentic RVFV and respond similarly to a wide array of known and previously unknown chemical inhibitors. This system should be useful for screening for small molecule inhibitors of RVFV replication
24-hour blood pressure recording in patients with orthostatic hypotension.
Continuous intra-arterial blood pressure measurement and electrocardiograms were obtained in two ambulatory patients with orthostatic hypotension due to autonomic dysfunction. Systolic and diastolic arterial pressure presented marked variations which took place mainly during the day and were related to several physical activities; however, marked falls in blood pressure were also observed during sleep and at the moment of arousal. A peak incidence of hypotensive events was found in the afternoon, mainly in the hours following the afternoon meal. Recording was repeated after 3 weeks of treatment with propranolol, 40 mg t.i.d. In patient 1, beta blockade drastically reduced the number and severity of hypotensive episodes, while propranolol failed to control blood pressure in patient 2, who experienced a higher number of hypotensive events during treatment. Findings of this study may be relevant to the management of patients with orthostatic hypotension and should contribute to a more accurate characterization of blood pressure profile in autonomic dysfunction
Orbital magnetoelectric effect in zigzag nanoribbons of p-band systems
Profiles of the spin and orbital angular momentum accumulations induced by a
longitudinally applied electric field are explored in nanoribbons of -band
systems with a honeycomb lattice. We show that nanoribbons with zigzag borders
can exhibit orbital magnetoelectric effects. More specifically, we have found
that purely orbital magnetization oriented perpendicularly to the ribbon may be
induced in these systems by means of the external electric field, when
sublattice symmetry is broken. The effect is rather general and may occur in
other multi-orbital materials.Comment: 10 pages, 4 figure
Disentangling orbital and valley Hall effects in bilayers of transition metal dichalcogenides
It has been recently shown that monolayers of transition metal
dichalcogenides (TMDs) in the 2H structural phase exhibit relatively large
orbital Hall conductivity plateaus within their energy band gaps, where their
spin Hall conductivities vanish. However, since the valley Hall effect (VHE) in
these systems also generates a transverse flow of orbital angular momentum it
becomes experimentally challenging to distinguish between the two effects in
these materials. The VHE requires inversion symmetry breaking to occur, which
takes place in the TMD monolayers, but not in the bilayers. We show that a
bilayer of 2H-MoS is an orbital Hall insulator that exhibits a sizeable OHE
in the absence of both spin and valley Hall effects. This phase can be
characterised by an orbital Chern number that assumes the value
for the 2H-MoS bilayer and for the
monolayer, confirming the topological nature of these orbital-Hall insulator
systems. Our results are based on density functional theory (DFT) and
low-energy effective model calculations and strongly suggest that bilayers of
TMDs are highly suitable platforms for direct observation of the orbital Hall
insulating phase in two-dimensional materials. Implications of our findings for
attempts to observe the VHE in TMD bilayers are also discussed.Comment: 7 pages, 4 figures + Supplementary materia
- …