Determining crystal structures through crowdsourcing and coursework

We show here that computer game players can build high-quality crystal structures. Introduction of a new feature into the computer game Foldit allows players to build and real-space refine structures into electron density maps. To assess the usefulness of this feature, we held a crystallographic model-building competition between trained crystallographers, undergraduate students, Foldit players and automatic model-building algorithms. After removal of disordered residues, a team of Foldit players achieved the most accurate structure. Analysing the target protein of the competition, YPL067C, uncovered a new family of histidine triad proteins apparently involved in the prevention of amyloid toxicity. From this study, we conclude that crystallographers can utilize crowdsourcing to interpret electron density information and to produce structure solutions of the highest quality

Changes in the aerobic faecal flora of patients treated with antibiotics for acute intra-abdominal infection

Background: An open observational study was performed to investigate changes in the rectal flora and antibiotic susceptibility among faecal bacteria in patients treated with antibiotics for acute intra-abdominal infection. Methods: One hundred and forty patients with acute intra-abdominal infection requiring antibiotic treatment and hospitalization were included. Eight surgical units from the southern part of Sweden participated, between January 2006 and November 2007. Antibiotic treatments were according to local guidelines. Rectal swabs were obtained on admission (sample 1) and 2-14 days after the end of antibiotic treatment (sample 2). Aerobic bacteria and yeasts were analysed. The material was divided into 2 groups: 1 group with Enterobacteriaceae and 1 group with non-fermentative Gram-negative bacteria. The susceptibility to antibiotics in each group was compared between samples 1 and 2. Results: The main finding of this study on patients with severe intra-abdominal infections was a shift in the aerobic faecal flora following antibiotic treatment, from Escherichia coli to other more resistant Enterobacteriaceae, Enterococcus faecium, and yeasts. The susceptibility to cephalosporins and piperacillin-tazobactam decreased in Enterobacteriaceae. Conclusions: Following antibiotic treatment, a shift in the aerobic rectal flora to species with intrinsic antibiotic resistance was observed. This indicates that the emergence of resistance is not due to new mutations, but rather to selection of more resistant species. This should be taken into account when designing treatments for secondary intra-abdominal infections

A broad range tagging spectrometer for the MAX-laboratory

A broad range tagging spectrometer together with a new beam transport system for photonuclear experiments at the MAX-laboratory in Lund is described. The spectrometer consists of a quadrupole followed by an Elbek-type dipole and has a large momentum acceptance. It can produce both polarized and unpolarized tagged photons in the energy range 10–80 MeV with an energy resolution of about 300 keV

The response of lead-tungstate scintillators (PWO) to photons with energies in the range 13 MeV-64 MeV

The response of a matrix of 25 lead tungstate (PWO) scintillator detectors, operated at -25 degrees C, to photons in the range 13 MeV-64 MeV has been measured at the tagged-photon facility at MAX-lab, Lund. The tapered PWO crystals, each with a length of 200 mm and a cross-section of 24.4 x 24.4 mm(2) in the front end, read out by 19 mm photomultiplier tubes, were arranged in a 5 x 5 matrix. The response was measured for photons directed towards the centre of the central crystal as well as for photons directed towards the corner of the central crystal, where four crystals meet. The obtained energy resolution surpasses what has been published so far and is close to the limit given by Poisson statistics and escaped energy. For photons directed towards the centre(corner) of the central crystal the relative energy resolution, defined as (FWHM/2.35)/E-gamma, decreases from 7.3%(11.0%) at E-gamma = 13 MeV to 3.3%(3.6%) at E-gamma = 64 MeV. The reconstructed point of impact of a photon in this energy range is determined with an uncertainty (one standard deviation) of 7.3 +/- 0.1 mm. (C) 2012 Elsevier B.V. All rights reserved

Growth hormone overexpression in the central nervous system results in hyperphagia-induced obesity associated with insulin resistance and dyslipidemia

It is well known that peripherally administered growth hormone (GH) results in decreased body fat mass. However, GH-deficient patients increase their food intake when substituted with GH, suggesting that GH also has an appetite stimulating effect. Transgenic mice with an overexpression of bovine GH in the central nervous system (CNS) were created to investigate the role of GH in CNS. This study shows that overexpression of GH in the CNS differentiates the effect of GH on body fat mass from that on appetite. The transgenic mice were not GH-deficient but were obese and showed increased food intake as well as increased hypothalamic expression of agouti-related protein and neuropeptide Y. GH also had an acute effect on food intake following intra-cerebroventricular injection of C57BL/6 mice. The transgenic mice were severely hyperinsulinemic and showed a marked hyperplasia of the islets of Langerhans. In addition, the transgenic mice displayed alterations in serum lipid and lipoprotein levels and hepatic gene expression. In conclusion, GH overexpression in the CNS results in hyperphagia-induced obesity indicating a dual effect of GH with a central stimulation of appetite and a peripheral lipolytic effect

(γ,n) study of the isovector quadrupole resonance in 40Ca

The forward-to-backward asymmetry of neutrons emitted in the 40Ca(γ,n0) reaction was measured at photon energies in the range of 27–50 MeV. An energy-dependent asymmetry was observed that is interpreted as evidence of interference between the isovector quadrupole resonance and the giant dipole resonance. Data analysis in terms of semiclassical and direct-semidirect models estimate the isovector quadrupole resonance to be at an excitation energy of 31.0±1.5 MeV, with a width of 16.0±1.5 MeV, and exhausting most of the energy-weighted sum rule for the isovector quadrupole resonance