The nature of inter- and intramolecular interactions in F2OXe…HX (X= F, Cl, Br, I) complexes

Electronic structure of the XeOF2 molecule and its two complexes with HX (X= F, Cl, Br, I) molecules have been studied in the gas phase using quantum chemical topology methods: topological analysis of electron localization function (ELF), electron density, ρ(r), reduced gradient of electron density |RDG(r)| in real space, and symmetry adapted perturbation theory (SAPT) in the Hilbert space. The wave function has been approximated by the MP2 and DFT methods, using APF-D, B3LYP, M062X, and B2PLYP functionals, with the dispersion correction as proposed by Grimme (GD3). For the Xe-F and Xe=O bonds in the isolated XeOF2 molecule, the bonding ELF-localization basins have not been observed. According to the ELF results, these interactions are not of covalent nature with shared electron density. There are two stable F2OXe…HF complexes. The first one is stabilized by the F-H…F and Xe…F interactions (type I) and the second by the F-H…O hydrogen bond (type II). The SAPT analysis confirms the electrostatic term, Eelst (1) and the induction energy, Eind (2) to be the major contributors to stabilizing both types of complexes

Rotation of a spheroid in a simple shear at small Reynolds number

We derive an effective equation of motion for the orientational dynamics of a neutrally buoyant spheroid suspended in a simple shear flow, valid for arbitrary particle aspect ratios and to linear order in the shear Reynolds number. We show how inertial effects lift the degeneracy of the Jeffery orbits and determine the stabilities of the log-rolling and tumbling orbits at infinitesimal shear Reynolds numbers. For prolate spheroids we find stable tumbling in the shear plane, log-rolling is unstable. For oblate particles, by contrast, log-rolling is stable and tumbling is unstable provided that the aspect ratio is larger than a critical value. When the aspect ratio is smaller than this value tumbling turns stable, and an unstable limit cycle is born.Comment: 25 pages, 5 figure

Skeletal muscle plasticity and energy metabolism

Skeletal muscle is remarkable in its ability to adjust to our needs. It can change its energy stores and usage, as well as its total mass. Furthermore, skeletal muscle adapts to deactivate reactive oxygen species produced, which in turn can both damage cells and convey signals. The molecular mechanisms regulating skeletal muscle plasticity are many, including reactive oxygen species, AMPK, and FOXO. AMPK functions as a molecular energy sensor, while the FOXO proteins are transcription factors that bind to the DNA, and regulate gene transcription. To understand the role of reactive oxygen species in health, we investigated how an intravenous antioxidant infusion of N-acetyl-cysteine (NAC), affected exercise-modulated insulin sensitivity. We found that NAC infusion decreased whole-body insulin sensitivity and skeletal muscle p70S6K phosphorylation, indicating diminished glucose uptake and attenuated protein synthesis. We also investigated the changes occurring in the atrophying skeletal muscle of individuals with spinal cord injury. We find that AMPK signaling decreases during the first year after injury, and that protein content of the AMPK regulatory γ1 subunit decreased, and γ3 increased. Skeletal muscle energy metabolism decreased during the first year after spinal cord injury, as indicated by the decreased protein content of the mitochondrial respiration complexes I-III. The contractile myosin heavy chain proteins myosin heavy chain 1 declined, and myosin heavy chain IIa increased 12 months after spinal cord injury. In order to understand how the changes in energy metabolizing and contractile proteins occurred, we investigated the mechanisms mediating protein degradation and synthesis, namely translation, autophagy and proteasomal degradation. We found that protein content of LC3II, as well as protein content and phosphorylation of S6 kinase, increased transiently during the first year after injury, indicating a temporary increase in autophagy and protein synthesis. We also detected stably increased levels of Lys48 poly-ubiquitinated proteins, indicating constantly increased proteasomal degradation during the first year after injury. Additionally, FOXO3 protein content, and FOXO1 phosphorylation decreased during the first year after spinal cord injury. To better understand the metabolic role of FOXO proteins, we transfected mouse skeletal muscle with FOXO proteins modified to bind to the DNA without activating transcription, leading to inhibited expression of FOXO regulated genes. We find that inhibition FOXO transcriptional activity decreased skeletal muscle glucose uptake, and increased inflammatory signaling and immune cell infiltration. Together, these studies partly elucidate how skeletal muscle adapts to its changing environment. We find that reactive oxygen species appear to be involved in the beneficial effects of exercise, and we unravel the signals and mechanisms mediating decreased skeletal muscle mass after spinal cord injury. Finally, we find that FOXO proteins directly affect gene networks involved in regulating inflammation and glucose metabolism in skeletal muscle

The role of inertia for the rotation of a nearly spherical particle in a general linear flow

We analyse the angular dynamics of a neutrally buoyant nearly spherical particle immersed in a steady general linear flow. The hydrodynamic torque acting on the particle is obtained by means of a reciprocal theorem, regular perturbation theory exploiting the small eccentricity of the nearly spherical particle, and assuming that inertial effects are small, but finite.Comment: 7 pages, 1 figur

Comparing laparoscopic antireflux surgery with esomeprazole in the management of patients with chronic gastro-oesophageal reflux disease: a 3-year interim analysis of the LOTUS trial

BACKGROUND: With the introduction of laparoscopic antireflux surgery (LARS) for gastro-oesophageal reflux disease (GORD) along with the increasing efficacy of modern medical treatment, a direct comparison is warranted. The 3-year interim results of a randomised study comparing both the efficacy and safety of LARS and esomeprazole (ESO) are reported. METHODS: LOTUS is an open, parallel-group multicentre, randomised and controlled trial conducted in dedicated centres in 11 European countries. LARS was completed according to a standardised protocol, comprising a total fundoplication and a crural repair. Medical treatment comprised ESO 20 mg once daily, which could be increased stepwise to 40 mg once daily and then 20 mg twice daily in the case of incomplete GORD control. The primary outcome variable was time to treatment failure (Kaplan-Meier analysis). Treatment failure was defined on the basis of symptomatic relapse requiring treatment beyond that stated in the protocol. RESULTS: 554 patients were randomised, of whom 288 were allocated to LARS and 266 to ESO. The two study arms were well matched. The proportions of patients who remained in remission after 3 years were similar for the two therapies: 90% of surgical patients compared with 93% medically treated for the intention to treat population, p = 0.25 (90% vs 95% per protocol). No major unexpected postoperative complications were experienced and ESO was well tolerated. However, postfundoplication complaints remain a problem after LARS. CONCLUSIONS: Over the first 3 years of this long-term study, both laparoscopic total fundoplication and continuous ESO treatment were similarly effective and well-tolerated therapeutic strategies for providing effective control of GORD

FÖRSTER TRANSFER CALCULATIONS BASED ON CRYSTAL STRUCTURE DATA FROM Agmenellum quadruplicatum C-PHYCOCYANIN

Excitation energy transfer in C-phycocyanin is modeled using the Forster inductive resonance mechanism. Detailed calculations are carried out using coordinates and orientations of the chromophores derived from X-ray crystallographic studies of C-phycocyanin from two different species (Schirmer et al, J. Mol. Biol. 184, 257–277 (1985) and ibid., 188, 651-677 (1986)). Spectral overlap integrals are estimated from absorption and fluorescence spectra of C-phycocyanin of Mastigocladus laminosus and its separated subunits. Calculations are carried out for the β-subunit, αβ-monomer, (αβ)3-trimer and (αβ)0-hexamer species with the following chromophore assignments: β155 = 's’(sensitizer), β84 =‘f (fluorescer) and α84 =‘m’(intermediate):]:. The calculations show that excitation transfer relaxation occurs to 3=98% within 200 ps in nearly every case; however, the rates increase as much as 10-fold for the higher aggregates. Comparison with experimental data on fluorescence decay and depolarization kinetics from the literature shows qualitative agreement with these calculations. We conclude that Forster transfer is sufficient to account for all of the observed fluorescence properties of C-phycocyanin in aggregation states up to the hexamer and in the absence of linker polypeptides

Picosecond time-resolved fluorescence of phycobiliproteins

The α- and β-subunits of C-phycocyanin from Mastigocladus laminosus were prepared according to revised procedures. Both subunits are isolated as dimers, which can be dissociated into monomers with detergent mixtures. The fluorescence decay kinetics are similar for the respective monomers and dimers. In no case could they be fitted by only one (α-subunit) or two exponentials (β-subunit) which are predicted by theory for samples with a unique chromophore—protein arrangement containing one and two chromophores, respectively. It is suggested that there exists a heterogeneity among the chromophores of the subunits, which may persist in the highly aggregated complexes present in cyanobacterial antennas

Cancer risks following diagnostic and therapeutic radiation exposure in children

The growing use of interventional and fluoroscopic imaging in children represents a tremendous benefit for the diagnosis and treatment of benign conditions. Along with the increasing use and complexity of these procedures comes concern about the cancer risk associated with ionizing radiation exposure to children. Children are considerably more sensitive to the carcinogenic effects of ionizing radiation than adults, and children have a longer life expectancy in which to express risk. Numerous epidemiologic cohort studies of childhood exposure to radiation for treatment of benign diseases have demonstrated radiation-related risks of cancer of the thyroid, breast, brain and skin, as well as leukemia. Many fewer studies have evaluated cancer risk following diagnostic radiation exposure in children. Although radiation dose for a single procedure might be low, pediatric patients often receive repeated examinations over time to evaluate their conditions, which could result in relatively high cumulative doses. Several cohort studies of girls and young women subjected to multiple diagnostic radiation exposures have been informative about increased mortality from breast cancer with increasing radiation dose, and case-control studies of childhood leukemia and postnatal diagnostic radiation exposure have suggested increased risks with an increasing number of examinations. Only two long-term follow-up studies of cancer following cardiac catheterization in childhood have been conducted, and neither reported an overall increased risk of cancer. Most cancers can be induced by radiation, and a linear dose-response has been noted for most solid cancers. Risks of radiation-related cancer are greatest for those exposed early in life, and these risks appear to persist throughout life