Colchicine therapy in acute coronary syndrome patients acts on caspase-1 to suppress NLRP3 inflammasome monocyte activation

Inflammasome activation, with subsequent release of pro-inflammatory cytokines interleukin-1β (IL-1β) and IL-18, has recently been implicated in atherosclerosis-associated inflammation. This study aims to assess in acute coronary syndrome (ACS) patients (1) inflammasome activation in circulating monocytes and (2) whether short-term oral colchicine, a recognized anti-inflammatory agent that has been shown to be cardio-protective in clinical studies, might acutely suppress inflammasome-dependent inflammation. ACS patients (n=21) were randomized to oral colchicine (1 mg followed by 0.5 mg 1 h later) or no treatment, and compared with untreated healthy controls (n=9). Peripheral venous blood was sampled pre- (day 1) and 24 h post- (day 2) treatment. Monocytes were cultured and stimulated with ATP. Analysis of key inflammasome markers was performed by ELISA. IL-1β secretion increased by 580.4% (P<0.01) in ACS patients compared with controls but only with ATP stimulation. Untreated ACS patients secreted significantly higher levels of IL-18 compared with healthy controls independent of ATP stimulation (P<0.05). Colchicine treatment in ACS patients markedly reduced intracellular and secreted levels of IL-1β compared with pre-treatment levels (P<0.05 for both), as well as significantly reducing pro-caspase-1 mRNA levels by 57.7% and secreted caspase-1 protein levels by 30.2% compared with untreated patients (P<0.05 for both). Monocytes from ACS patients are ‘primed’ to secrete inflammasome-related cytokines and short-term colchicine acutely and markedly suppresses monocyte caspase-1 activity, thereby reducing monocyte secretion of IL-1β

Dynamical model of the dielectric screening of conjugated polymers

A dynamical model of the dielectric screening of conjugated polymers is introduced and solved using the density matrix renormalization group method. The model consists of a line of quantized dipoles interacting with a polymer chain. The polymer is modelled by the Pariser-Parr-Pople (P-P-P) model. It is found that: (1) Compared to isolated, unscreened single chains, the screened 1Bu- exciton binding energy is typically reduced by ca. 1 eV to just over 1 eV; (2) Covalent (magnon and bi-magnon) states are very weakly screened compared to ionic (exciton) states; (3) Screening of the 1Bu- exciton is closer to the dispersion than solvation limit.Comment: 12 pages, 2 figure

Mixing of magnetic and phononic excitations in incommensurate Spin-Peierls systems

We analyze the excitation spectra of a spin-phonon coupled chain in the presence of a soliton. This is taken as a microscopic model of a Spin-Peierls material placed in a high magnetic field. We show, by using a semiclassical approximation in the bosonized representation of the spins that a trapped magnetic state obtained in the adiabatic approximation is destroyed by dynamical phonons. Low energy states are phonons trapped by the soliton. When the magnetic gap is smaller than the phonon frequencies the only low energy state is a mixed magneto-phonon state with the energy of the gap. We emphasize that our results are relevant for the Raman spectra of the inorganic Spin-Peierls material CuGeO$_3$.Comment: 5 pages, latex, 2 figures embedded in the tex

Peierls transition in the presence of finite-frequency phonons in the one-dimensional extended Peierls-Hubbard model at half-filling

We report quantum Monte Carlo (stochastic series expansion) results for the transition from a Mott insulator to a dimerized Peierls insulating state in a half-filled, 1D extended Hubbard model coupled to optical bond phonons. Using electron-electron (e-e) interaction parameters corresponding approximately to polyacetylene, we show that the Mott-Peierls transition occurs at a finite value of the electron-phonon (e-ph) coupling. We discuss several different criteria for detecting the transition and show that they give consistent results. We calculate the critical e-ph coupling as a function of the bare phonon frequency and also investigate the sensitivity of the critical coupling to the strength of the e-e interaction. In the limit of strong e-e couplings, we map the model to a spin-Peierls chain and compare the phase boundary with previous results for the spin-Peierls transition. We point out effects of a nonlinear spin-phonon coupling neglected in the mapping to the spin-Peierls model.Comment: 7 pages, 5 figure

Magnetism in all-carbon nanostructures with negative gaussian curvature

The electronic and magnetic properties of an sp2 bonded all-carbon nanostructure, consisting of a nanotube junction structurally related to schwarzite, were investigated. The spin density functional theory was used during the investigation. The electronic structure of different tetrapods was calculated using the density functional theory within the local spin density approximation (LSDA). It was found that particular systems, which were related to schwarzite and contain no under-coordinated carbon atoms, carry a net magnetic moment in the ground state. The effect of edge termination on the net magnetic moment of the tetrapod was also studied.open13713

Ab initio study of ferroelectric domain walls in PbTiO3

We have investigated the atomistic structure of the 180-degree and 90-degree domain boundaries in the ferroelectric perovskite compound PbTiO3 using a first-principles ultrasoft-pseudopotential approach. For each case we have computed the position, thickness and creation energy of the domain walls, and an estimate of the barrier height for their motion has been obtained. We find both kinds of domain walls to be very narrow with a similar width of the order of one to two lattice constants. The energy of the 90-dergree domain wall is calculated to be 35 mJ/m^2, about a factor of four lower than the energy of its 180-degree counterpart, and only a miniscule barrier for its motion is found. As a surprising feature we detected a small offset of 0.15-0.2 eV in the electrostatic potential across the 90-degree domain wall.Comment: 12 pages, with 9 postscript figures embedded. Uses REVTEX and epsf macros. Also available at http://www.physics.rutgers.edu/~dhv/preprints/bm_dw/index.htm

The afterlives and memory politics of the Ipoh Cenotaph in Perak, Malaysia

As political regimes undergo changes, so do memorial landscapes established by or associated with them. Such is also the case when new nations are born out of the ashes of decolonization, where monuments of former imperial rule may be co-opted, displaced or destroyed to mark the transition between authorities. Yet, such re-appropriations are not always state-led and do not necessarily take place only during critical junctures of regime changes. Furthermore, original meanings embedded within them may not be totally erased as they leave traces. Drawing on the Cenotaph Remembrance in Ipoh, Malaysia, in 2008, this paper examines how a British monument honouring the imperial war dead, which has been largely neglected since Malay(si)a’s independence in 1957, has been readapted from the bottom-up as an inclusive memorial – via new symbolic accretions and a ceremony – to mark the memory of both locals and foreigners sacrificed during conflicts throughout Malaysian history. While these measures have, to a certain extent, rescued the formerly British-focused monument from obscurity, the paper unravels issues rendering the re-adaptation a highly contested affair, derived primarily from recalcitrant colonial memories and the multi-ethnic complexion of the Malaysian nation