Novel sialic acid derivatives lock open the 150-loop of an influenza A virus group-1 sialidase

This work was supported by the Medical Research Council and the Scottish Funding Council.Influenza virus sialidase has an essential role in the virus’ life cycle. Two distinct groups of influenza A virus sialidases have been established, that differ in the flexibility of the ‘150-loop’, providing a more open active site in the apo form of the group-1 compared to group-2 enzymes. In this study we show, through a multidisciplinary approach, that novel sialic acid-based derivatives can exploit this structural difference and selectively inhibit the activity of group-1 sialidases. We also demonstrate that group-1 sialidases from drug-resistant mutant influenza viruses are sensitive to these designed compounds. Moreover, we have determined, by protein X-ray crystallography, that these inhibitors lock open the group-1 sialidase flexible 150-loop, in agreement with our molecular modelling prediction. This is the first direct proof that compounds may be developed to selectively target the pandemic A/H1N1, avian A/H5N1 and other group-1 sialidase-containing viruses, based on an open 150-loop conformation of the enzyme.Publisher PDFPeer reviewe

Coal fly ash: Linking immersion freezing behavior and physicochemical particle properties

To date, only a few studies have investigated the potential of coal fly ash particles to trigger heterogeneous ice nucleation in cloud droplets. The presented measurements aim at expanding the sparse dataset and improving process understanding of how physicochemical particle properties can influence the freezing behavior of coal fly ash particles immersed in water. Firstly, immersion freezing measurements were performed with two single particle techniques, i.e., the Leipzig Aerosol Cloud Interaction Simulator (LACIS) and the SPectrometer for Ice Nuclei (SPIN). The effect of suspension time on the efficiency of the coal fly ash particles when immersed in a cloud droplet is analyzed based on the different residence times of the two instruments and employing both dry and wet particle generation. Secondly, two cold-stage setups, one using microliter sized droplets (Leipzig Ice Nucleation Array) and one using nanoliter sized droplets (WeIzmann Supercooled Droplets Observation on Microarray setup) were applied. We found that coal fly ash particles are comparable to mineral dust in their immersion freezing behavior when being dry generated. However, a significant decrease in immersion freezing efficiency was observed during experiments with wet-generated particles in LACIS and SPIN. The efficiency of wet-generated particles is in agreement with the cold-stage measurements. In order to understand the reason behind the deactivation, a series of chemical composition, morphology, and crystallography analyses (single particle mass spectrometry, scanning electron microscopy coupled with energy dispersive X-ray microanalysis, X-ray diffraction analysis) were performed with dry- and wet-generated particles. From these investigations, we conclude that anhydrous CaSO4 and CaO - which, if investigated in pure form, show the same qualitative immersion freezing behavior as observed for dry-generated coal fly ash particles - contribute to triggering heterogeneous ice nucleation at the particle-water interface. The observed deactivation in contact with water is related to changes in the particle surface properties which are potentially caused by hydration of CaSO4 and CaO. The contribution of coal fly ash to the ambient population of ice-nucleating particles therefore depends on whether and for how long particles are immersed in cloud droplets

Challenges in measuring nitrogen isotope signatures in inorganic nitrogen forms: An interlaboratory comparison of three common measurement approaches

Rationale Stable isotope approaches are increasingly applied to better understand the cycling of inorganic nitrogen (Ni) forms, key limiting nutrients in terrestrial and aquatic ecosystems. A systematic comparison of the accuracy and precision of the most commonly used methods to analyze δ15N in NO3− and NH4+ and interlaboratory comparison tests to evaluate the comparability of isotope results between laboratories are, however, still lacking. Methods Here, we conducted an interlaboratory comparison involving 10 European laboratories to compare different methods and laboratory performance to measure δ15N in NO3− and NH4+. The approaches tested were (a) microdiffusion (MD), (b) chemical conversion (CM), which transforms Ni to either N2O (CM-N2O) or N2 (CM-N2), and (c) the denitrifier (DN) methods. Results The study showed that standards in their single forms were reasonably replicated by the different methods and laboratories, with laboratories applying CM-N2O performing superior for both NO3− and NH4+, followed by DN. Laboratories using MD significantly underestimated the “true” values due to incomplete recovery and also those using CM-N2 showed issues with isotope fractionation. Most methods and laboratories underestimated the at%15N of Ni of labeled standards in their single forms, but relative errors were within maximal 6% deviation from the real value and therefore acceptable. The results showed further that MD is strongly biased by nonspecificity. The results of the environmental samples were generally highly variable, with standard deviations (SD) of up to ± 8.4‰ for NO3− and ± 32.9‰ for NH4+; SDs within laboratories were found to be considerably lower (on average 3.1‰). The variability could not be connected to any single factor but next to errors due to blank contamination, isotope normalization, and fractionation, and also matrix effects and analytical errors have to be considered

Host specificity and species colouration mediate the regional decline of nocturnal moths in central European forests

The high diversity of insects has limited the volume of long-term community data with a high taxonomic resolution and considerable geographic replications, especially in forests. Therefore, trends and causes of changes are poorly understood. Here we analyse trends in species richness, abundance and biomass of nocturnal macro moths in three quantitative data sets collected over four decades in forests in southern Germany. Two local data sets, one from coppiced oak forests and one from high oak forests included 125K and 48K specimens from 559 and 532 species, respectively. A third regional data set, representing all forest types in the temperate zone of central Europe comprised 735K specimens from 848 species. Generalized additive mixed models revealed temporal declines in species richness (−38%), abundance (−53%) and biomass (−57%) at the regional scale. These were more pronounced in plant host specialists and in dark coloured species. In contrast, the local coppiced oak forests showed an increase, in species richness (+62%), while the high oak forests showed no clear trends. Left and right censoring as well as cross validation confirmed the robustness of the analyses, which led to four conclusions. First, the decline in insects appears in hyper diverse insect groups in forests and affects species richness, abundance and biomass. Second, the pronounced decline in host specialists suggests habitat loss as an important driver of the observed decline. Third, the more severe decline in dark species might be an indication of global warming as a potential driver. Fourth, the trends in coppiced oak forests indicate that maintaining complex and diverse forest ecosystems through active management may be a promising conservation strategy in order to counteract negative trends in biodiversity, alongside rewilding approaches

Plant families exhibit unique geographic trends in C4 richness and cover in Australia

Numerous studies have analysed the relationship between C4 plant cover and climate. However, few have examined how different C4 taxa vary in their response to climate, or how environmental factors alter C4:C3 abundance. Here we investigate (a) how proportional C4 plant cover and richness (relative to C3) responds to changes in climate and local environmental factors, and (b) if this response is consistent among families. Proportional cover and richness of C4 species were determined at 541 one-hectare plots across Australia for 14 families. C4 cover and richness of the most common and abundant families were regressed against climate and local parameters. C4 richness and cover in the monocot families Poaceae and Cyperaceae increased with latitude and were strongly positively correlated with January temperatures, however C4 Cyperaceae occupied a more restricted temperature range. Seasonal rainfall, soil pH, soil texture, and tree cover modified proportional C4 cover in both families. Eudicot families displayed considerable variation in C4 distribution patterns. Proportional C4 Euphorbiaceae richness and cover were negatively correlated with increased moisture availability (i.e. high rainfall and low aridity), indicating they were more common in dry environments. Proportional C4 Chenopodiaceae richness and cover were weakly correlated with climate and local environmental factors, including soil texture. However, the explanatory power of C4 Chenopodiaceae models were poor, suggesting none of the factors considered in this study strongly influenced Chenopodiaceae distribution. Proportional C4 richness and cover in Aizoaceae, Amaranthaceae, and Portulacaceae increased with latitude, suggesting C4 cover and richness in these families increased with temperature and summer rainfall, but sample size was insufficient for regression analysis. Results demonstrate the unique relationships between different C4 taxa and climate, and the significant modifying effects of environmental factors on C4 distribution. Our work also revealed C4 families will not exhibit similar responses to local perturbations or climate.Samantha E. M. MunroeID, Francesca A. McInerney, Greg R. Guerin, Jake W. Andrae, Nina WeltiID, Stefan Caddy-Retalic, Rachel Atkins, Ben Sparro

LHC Optics Measurement with Proton Tracks Detected by the Roman Pots of the TOTEM Experiment

Precise knowledge of the beam optics at the LHC is crucial to fulfil the physics goals of the TOTEM experiment, where the kinematics of the scattered protons is reconstructed with the near-beam telescopes -- so-called Roman Pots (RP). Before being detected, the protons' trajectories are influenced by the magnetic fields of the accelerator lattice. Thus precise understanding of the proton transport is of key importance for the experiment. A novel method of optics evaluation is proposed which exploits kinematical distributions of elastically scattered protons observed in the RPs. Theoretical predictions, as well as Monte Carlo studies, show that the residual uncertainty of this optics estimation method is smaller than 0.25 percent.Comment: 20 pages, 11 figures, 5 figures, to be submitted to New J. Phy

Double diffractive cross-section measurement in the forward region at LHC

The first double diffractive cross-section measurement in the very forward region has been carried out by the TOTEM experiment at the LHC with center-of-mass energy of sqrt(s)=7 TeV. By utilizing the very forward TOTEM tracking detectors T1 and T2, which extend up to |eta|=6.5, a clean sample of double diffractive pp events was extracted. From these events, we measured the cross-section sigma_DD =(116 +- 25) mub for events where both diffractive systems have 4.7 <|eta|_min < 6.5 .Comment: 5 pages, 1 figure, submitted for publicatio

Prostate-specific Membrane Antigen Heterogeneity and DNA Repair Defects in Prostate Cancer.

BackgroundProstate-specific membrane antigen (PSMA; folate hydrolase) prostate cancer (PC) expression has theranostic utility.ObjectiveTo elucidate PC PSMA expression and associate this with defective DNA damage repair (DDR).Design, setting, and participantsMembranous PSMA (mPSMA) expression was scored immunohistochemically from metastatic castration-resistant PC (mCRPC) and matching, same-patient, diagnostic biopsies, and correlated with next-generation sequencing (NGS) and clinical outcome data.Outcome measurements and statistical analysisExpression of mPSMA was quantitated by modified H-score. Patient DNA was tested by NGS. Gene expression and activity scores were determined from mCRPC transcriptomes. Statistical correlations utilised Wilcoxon signed rank tests, survival was estimated by Kaplan-Meier test, and sample heterogeneity was quantified by Shannon's diversity index.Results and limitationsExpression of mPSMA at diagnosis was associated with higher Gleason grade (p=0.04) and worse overall survival (p=0.006). Overall, mPSMA expression levels increased at mCRPC (median H-score [interquartile range]: castration-sensitive prostate cancer [CSPC] 17.5 [0.0-60.0] vs mCRPC 55.0 [2.8-117.5]). Surprisingly, 42% (n=16) of CSPC and 27% (n=16) of mCRPC tissues sampled had no detectable mPSMA (H-score ConclusionsMembranous PSMA expression is upregulated in some but not all PCs, with mPSMA expression demonstrating marked inter- and intrapatient heterogeneity. DDR aberrations are associated with higher mPSMA expression and merit further evaluation as predictive biomarkers of response for PSMA-targeted therapies in larger, prospective cohorts.Patient summaryThrough analysis of prostate cancer samples, we report that the presence of prostate-specific membrane antigen (PSMA) is extremely variable both within one patient and between different patients. This may limit the usefulness of PSMA scans and PSMA-targeted therapies. We show for the first time that prostate cancers with defective DNA repair produce more PSMA and so may respond better to PSMA-targeting treatments

Performance of the TOTEM Detectors at the LHC

The TOTEM Experiment is designed to measure the total proton-proton cross-section with the luminosity-independent method and to study elastic and diffractive pp scattering at the LHC. To achieve optimum forward coverage for charged particles emitted by the pp collisions in the interaction point IP5, two tracking telescopes, T1 and T2, are installed on each side of the IP in the pseudorapidity region 3.1 < = |eta | < = 6.5, and special movable beam-pipe insertions - called Roman Pots (RP) - are placed at distances of +- 147 m and +- 220 m from IP5. This article describes in detail the working of the TOTEM detector to produce physics results in the first three years of operation and data taking at the LHC.Comment: 40 pages, 31 figures, submitted to Int. J. Mod. Phys.

A phase I dose-escalation study of enzalutamide in combination with the AKT inhibitor AZD5363 (capivasertib) in patients with metastatic castration-resistant prostate cancer.

Background Activation of the PI3K/AKT/mTOR pathway through loss of phosphatase and tensin homolog (PTEN) occurs in approximately 50% of patients with metastatic castration-resistant prostate cancer (mCRPC). Recent evidence suggests that combined inhibition of the androgen receptor (AR) and AKT may be beneficial in mCRPC with PTEN loss.Patients and methods mCRPC patients who previously failed abiraterone and/or enzalutamide, received escalating doses of AZD5363 (capivasertib) starting at 320 mg twice daily (b.i.d.) given 4 days on and 3 days off, in combination with enzalutamide 160 mg daily. The co-primary endpoints were safety/tolerability and determining the maximum tolerated dose and recommended phase II dose; pharmacokinetics, antitumour activity, and exploratory biomarker analysis were also evaluated.Results Sixteen patients were enrolled, 15 received study treatment and 13 were assessable for dose-limiting toxicities (DLTs). Patients were treated at 320, 400, and 480 mg b.i.d. dose levels of capivasertib. The recommended phase II dose identified for capivasertib was 400 mg b.i.d. with 1/6 patients experiencing a DLT (maculopapular rash) at this level. The most common grade ≥3 adverse events were hyperglycemia (26.7%) and rash (20%). Concomitant administration of enzalutamide significantly decreased plasma exposure of capivasertib, though this did not appear to impact pharmacodynamics. Three patients met the criteria for response (defined as prostate-specific antigen decline ≥50%, circulating tumour cell conversion, and/or radiological response). Responses were seen in patients with PTEN loss or activating mutations in AKT, low or absent AR-V7 expression, as well as those with an increase in phosphorylated extracellular signal-regulated kinase (pERK) in post-exposure samples.Conclusions The combination of capivasertib and enzalutamide is tolerable and has antitumour activity, with all responding patients harbouring aberrations in the PI3K/AKT/mTOR pathway.Clinical trial number NCT02525068