Molecular dynamics simulations of charged and neutral lipid bilayers : treatment of electrostatic interactions

Molecular dynamics (MD) simulations complement experimental methods in studies of the structure and dynamics of lipid bilayers. The choice of algorithms employed in this computational method represents a trade-off between the accuracy and real calculation time. The largest portion of the simulation time is devoted to calculation of long-range electrostatic interactions. To speed-up evaluation of these interactions, various approximations have been used. The most common ones are the truncation of long-range interactions with the use of cut-offs, and the particle-mesh Ewald (PME) method. In this study, several multi-nanosecond cut-off and PME simulations were performed to establish the influence of the simulation protocol on the bilayer properties. Two bilayers were used. One consisted of neutral phosphatidylcholine molecules. The other was a mixed lipid bilayer consisting of neutral phosphatidylethanolamine and negatively charged phosphatidylglycerol molecules. The study shows that the cut-off simulation of a bilayer containing charge molecules generates artefacts; in particular the mobility and order of the charged molecules are vastly different from those determined experimentally. In the PME simulation, the bilayer properties are in general agreement with experimental data. The cut-off simulation of bilayers containing only uncharged molecules does not generate artefacts, nevertheless, the PME simulation gives generally better agreement with experimental data

Marketing polityczny w wyborach prezydenckich w Rosji

"Historia marketingu politycznego w Rosji, a zwłaszcza politycznej reklamy oraz innych komunikacyjnych relacji ze społeczeństwem, nieodłącznie związana jest z demokratycznymi wyborami po 1989 r. Początków marketingu można doszukiwać się w wyborach delegatów na zjazd deputowanych ZSRR wiosną 1989 r., kiedy to wyborcy po raz pierwszy uzyskali możliwość niezależnego głosowania, a kandydaci, nienależący do partyjnej nomenklatury i elitarnych społecznych grup — możliwość wejścia do politycznej elity kraju poprzez status wybranego delegata"

Elucidation of xenobiotic metabolism pathways in human skin and human skin models by proteomic profiling

Human skin has the capacity to metabolise foreign chemicals (xenobiotics), but knowledge of the various enzymes involved is incomplete. A broad-based unbiased proteomics approach was used to describe the profile of xenobiotic metabolising enzymes present in human skin and hence indicate principal routes of metabolism of xenobiotic compounds. Several in vitro models of human skin have been developed for the purpose of safety assessment of chemicals. The suitability of these epidermal models for studies involving biotransformation was assessed by comparing their profiles of xenobiotic metabolising enzymes with those of human skin

Społeczny odbiór i funkcjonowanie mediów w Zagłębiu Dąbrowskim w okresie transformacji (1989-1999)

"Na wstępie należy podkreślić, iż Zagłębie Dąbrowskie w swych historycznych granicach i w obecnym kształcie nie posiadało, i nie posiada, własnej, autonomicznej siatki medialnej. Jedyny tytuł prasowy „Wiadomości Zagłębia”, przeznaczony dla społeczeństwa Zagłębia Dąbrowskiego, miał zawsze szerszy zasięg geograficzny. Obejmował on całą wschodnią część województwa katowickiego. Medialnie Zagłębie Dąbrowskie, wbrew pierwotnym, historycznym granicom, było zawsze traktowane jako całość obszaru na wschód od Brynicy. Najświeższym przykładem tego typu podejścia jest zasięg przestrzenny mutacji zagłębiowskich dzienników regionalnych „Trybuny Śląskiej” oraz „Dziennika Zachodniego”. Obejmują one pewne obszary, które nie miały nigdy żadnego związku z Zagłębiem Dąbrowskim. Dlatego też rozwój i funkcjonowanie mediów na obszarze Zagłębia Dąbrowskiego należy rozważać na tle rynku prasy, radia i telewizji byłego województwa katowickiego, a obecnie śląskiego." (fragment tekstu

Społeczne aspekty funkcjonowania prasy lokalnej w Rosji

The article is an attempt to characterize the local press in Russia. The author points to terminological problems connected with this typological group. There are many terms used, such as: local press, district press, city press, municipal press, ring press or even regional press. A statistical and quantitative analysis of city and district newspapers was also carried out. The conditions and factors influencing the development of the local press in a market economy were presented. Models of contemporary local press in Russia were also characterized. The most common are: a forum newspaper; a host-newspaper; a newspaper with life problems; or a newspaper - an “old activist”. The author presents the results of the research that characterize the relations between local authorities and the local press

Properties of water hydrating the galactolipid and phospholipid bilayers : a molecular dynamics simulation study

Molecular dynamics simulations of 1,2-di-O-acyl-3-O-β-D-galactopyranosyl-sn-glycerol (MGDG) and 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC) bilayers were carried out to compare the effect of the lipid head group's chemical structure on the dynamics and orientational order of the water molecules hydrating the bilayer. The effect of the bilayers on the diffusion of water is strong for the neighbouring water molecules i.e., those located not further than 4 Å from any bilayer atom. This is because the neighbouring water molecules are predominantly hydrogen bonded to the lipid oxygen atoms and their mobility is limited to a confined spatial volume. The choline group of DOPC and the galactose group of MGDG affect water diffusion less than the polar groups located deeper in the bilayer interface, and similarly. The latter is an unexpected result since interactions of water with these groups have a vastly different origin. The least affected by the bilayer lipids is the lateral diffusion of unbound water in the bilayer plane (x,y-plane) - it is because the diffusion is not confined by the periodic boundary conditions, whereas that perpendicular to the plane is. Interactions of water molecules with lipid groups also enforce certain orientations of water dipole moments. The profile of an average water orientation along the bilayer normal for the MGDG bilayer differs from that for the DOPC bilayer. In the DOPC bilayer, the ordering effect of the lipid head groups extends further into the water phase than in the MGDG bilayer, whereas inside the bilayer/water interface, ordering of the water dipoles in the MGDG bilayer is higher. It is possible that differences in the profiles of an average water orientation across the bilayer in the DOPC and MGDG bilayers are responsible for differences in the lateral pressure profiles of these bilayers

Cardiac magnetic resonance in patients with cardiac resynchronization therapy: is it time to scan with resynchronization on?

Cardiac resynchronization therapy (CRT) is recommended in international guidelines for patients with heart failure due to important left ventricular systolic dysfunction (or heart failure with reduced ejection fraction) and ventricular conduction tissue disease. Cardiac magnetic resonance (CMR) represents the most powerful imaging tool for dynamic assessment of the volumes and function of cardiac chambers but is rarely utilized in patients with CRT due to limitations on the device, programming and scanning. In this review, we explore the known utility of CMR in this cohort with discussion of the risks and potential benefits of scanning whilst CRT is active, including a practical strategy for conducting high quality scans safely. Our contention is that imaging in patients with CRT could be improved further by keeping resynchronization therapy active with resultant benefits on research and also patient outcomes

Optimisation of Pacemaker Therapy for Cardiac Function

Patients with right ventricular (RV) pacemakers are at increased risk of left ventricular (LV) systolic dysfunction (LVSD) and chronic heart failure (CHF). I aimed 1) to establish the prevalence of LVSD in patients with long-term RV pacemakers listed for pulse generator replacement (PGR), 2) to evaluate the effects on LV function of reprogramming existing pacemakers to reduce RV pacing (RVP) and 3) to investigate whether upgrade to cardiac resynchronization therapy (CRT) at the time of PGR is beneficial in patients with unavoidable RV pacing and LVSD. Data were collected on 491 patients listed for PGR. Reduced left ventricular ejection fraction (LVEF) <50% was observed in 40%. Multivariable analysis revealed %RVP, serum creatinine and previous myocardial infarction (MI) to be independently related to the presence of LVSD. An audit was performed to investigate the effects of optimising pacemaker programming to avoid RV pacing in 66 patients. At 6m, RV pacing was reduced by a mean of 49%, with a mean improvement in LVEF of 6% and no reduction in exercise capacity, NT-pro-BNP or quality of life. Fifty patients with unavoidable RV pacing, LVSD, and mild symptoms of CHF, listed for PGR were randomized 1:1 to either standard RV-PGR or CRT. At 6 months there was a difference in change in median LVEF, improvements in exercise capacity, quality of life, and NT-proBNP in those randomized to CRT. After 809 days, 17 patients had died or been hospitalized (6 CRT and 11 PGR) and two patients in the PGR arm required CRT for deteriorating CHF. In summary, LVSD is common in patients with standard RV pacemakers and relates to cardiovascular co-morbidities, careful reprogramming to avoid unnecessary RV pacing can improve LVEF without adversely affecting exercise capacity and quality of life and upgrading patients with unavoidable RV pacing to CRT at PGR improves LV function, and exercise tolerance and may reduce admissions and further upgrades