A comparison of transgenic rodent mutation and in vivo comet assay responses for 91 chemicals.

A database of 91 chemicals with published data from both transgenic rodent mutation (TGR) and rodent comet assays has been compiled. The objective was to compare the sensitivity of the two assays for detecting genotoxicity. Critical aspects of study design and results were tabulated for each dataset. There were fewer datasets from rats than mice, particularly for the TGR assay, and therefore, results from both species were combined for further analysis. TGR and comet responses were compared in liver and bone marrow (the most commonly studied tissues), and in stomach and colon evaluated either separately or in combination with other GI tract segments. Overall positive, negative, or equivocal test results were assessed for each chemical across the tissues examined in the TGR and comet assays using two approaches: 1) overall calls based on weight of evidence (WoE) and expert judgement, and 2) curation of the data based on a priori acceptability criteria prior to deriving final tissue specific calls. Since the database contains a high prevalence of positive results, overall agreement between the assays was determined using statistics adjusted for prevalence (using AC1 and PABAK). These coefficients showed fair or moderate to good agreement for liver and the GI tract (predominantly stomach and colon data) using WoE, reduced agreement for stomach and colon evaluated separately using data curation, and poor or no agreement for bone marrow using both the WoE and data curation approaches. Confidence in these results is higher for liver than for the other tissues, for which there were less data. Our analysis finds that comet and TGR generally identify the same compounds (mainly potent mutagens) as genotoxic in liver, stomach and colon, but not in bone marrow. However, the current database content precluded drawing assay concordance conclusions for weak mutagens and non-DNA reactive chemicals

Does a 'direct' transfer protocol reduce time to coronary angiography for patients with non-ST-elevation acute coronary syndromes? A prospective observational study.

OBJECTIVE: National guidelines recommend 'early' coronary angiography within 96 h of presentation for patients with non-ST elevation acute coronary syndromes (NSTE-ACS). Most patients with NSTE-ACS present to their district general hospital (DGH), and await transfer to the regional cardiac centre for angiography. This care model has inherent time delays, and delivery of timely angiography is problematic. The objective of this study was to assess a novel clinical care pathway for the management of NSTE-ACS, known locally as the Heart Attack Centre-Extension or HAC-X, designed to rapidly identify patients with NSTE-ACS while in DGH emergency departments (ED) and facilitate transfer to the regional interventional centre for 'early' coronary angiography. METHODS: This was an observational study of 702 patients divided into two groups; 391 patients treated before the instigation of the HAC-X pathway (Pre-HAC-X), and 311 patients treated via the novel pathway (Post-HAC-X). Our primary study end point was time from ED admission to coronary angiography. We also assessed the length of hospital stay. RESULTS: Median time from ED admission to coronary angiography was 7.2 (IQR 5.1-10.2) days pre-HAC-X compared to 1.0 (IQR 0.7-2.0) day post-HAC-X (p<0.001). Median length of hospital stay was 3.0 (IQR 2.0-6.0) days post-HAC-X v 9.0 (IQR 6.0-14.0) days pre-HAC-X (p<0.0005). This equates to a reduction of six hospital bed days per NSTE-ACS admission. CONCLUSIONS: The introduction of this novel care pathway was associated with significant reductions in time to angiography and in total hospital bed occupancy for patients with NSTE-ACS

Generating mice with targeted mutations.

Journal ArticleMutational analysis is one of the most informative approaches available for the study of complex biological processes. It has been particularly successful in the analysis of the biology of bacteria, yeast, the nematode worm Caenorhabditis elegans and the fruit fly Drosophila melanogaster. Extension of this approach to the mouse, through informative, was far less successful relative to what has been achieved with these simpler model organisms. This is because it is not numerically practical in mice to use random mutagenesis to isolate mutations that affect a specified biological process of interest. Nonetheless, biological phenomena such as a sophisticated immune response, cancer, vascular disease or higher-order cognitive function, to mention just a few, must analyzed in organisms that show such phenomena, and for this reason geneticists and other researchers have turned to the mouse. Gene targeting, the means for creating mice with designed mutations in almost any gene, was developed as an alternative to the impractical use of random mutgenesis for pursing genetic analysis in the mouse. Now gene targeting has advanced the genomic manipulations possible in mice to a level that can be matched only in far simple organisms such as bacteria and yeast

The Hubble Constant

I review the current state of determinations of the Hubble constant, which gives the length scale of the Universe by relating the expansion velocity of objects to their distance. There are two broad categories of measurements. The first uses individual astrophysical objects which have some property that allows their intrinsic luminosity or size to be determined, or allows the determination of their distance by geometric means. The second category comprises the use of all-sky cosmic microwave background, or correlations between large samples of galaxies, to determine information about the geometry of the Universe and hence the Hubble constant, typically in a combination with other cosmological parameters. Many, but not all, object-based measurements give $H_0$ values of around 72-74km/s/Mpc , with typical errors of 2-3km/s/Mpc. This is in mild discrepancy with CMB-based measurements, in particular those from the Planck satellite, which give values of 67-68km/s/Mpc and typical errors of 1-2km/s/Mpc. The size of the remaining systematics indicate that accuracy rather than precision is the remaining problem in a good determination of the Hubble constant. Whether a discrepancy exists, and whether new physics is needed to resolve it, depends on details of the systematics of the object-based methods, and also on the assumptions about other cosmological parameters and which datasets are combined in the case of the all-sky methods.Comment: Extensively revised and updated since the 2007 version: accepted by Living Reviews in Relativity as a major (2014) update of LRR 10, 4, 200

TALEN-mediated editing of the mouse Y chromosome

The functional study of Y chromosome genes has been hindered by a lack of mouse models with specific Y chromosome mutations. We used transcription activator-like effector nuclease (TALEN)-mediated gene editing in mouse embryonic stem cells (mESCs) to produce mice with targeted gene disruptions and insertions in two Y-linked genes—Sry and Uty. TALEN-mediated gene editing is a useful tool for dissecting the biology of the Y chromosome.National Institutes of Health (U.S.) (US NIH grant R01-HG000257)National Institutes of Health (U.S.) (US NIH grant R01-CA084198)National Institutes of Health (U.S.) (US NIH grant R37-HD045022)Croucher Foundation (Scholarship)Howard Hughes Medical Institute (Investigator

Origin of micro-scale heterogeneity in polymerisation of photo-activated resin composites

Photo-activated resin composites are widely used in industry and medicine. Despite extensive chemical characterisation, the micro-scale pattern of resin matrix reactive group conversion between filler particles is not fully understood. Using an advanced synchrotron-based wide-field IR imaging system and state-of-the-art Mie scattering corrections, we observe how the presence of monodispersed silica filler particles in a methacrylate based resin reduces local conversion and chemical bond strain in the polymer phase. Here we show that heterogeneity originates from a lower converted and reduced bond strain boundary layer encapsulating each particle, whilst at larger inter-particulate distances light attenuation and monomer mobility predominantly influence conversion. Increased conversion corresponds to greater bond strain, however, strain generation appears sensitive to differences in conversion rate and implies subtle distinctions in the final polymer structure. We expect these findings to inform current predictive models of mechanical behaviour in polymer-composite materials, particularly at the resin-filler interface

Expression of the ubiquitin-proteasome pathway and muscle loss in experimental cancer cachexia

Muscle protein degradation is thought to play a major role in muscle atrophy in cancer cachexia. To investigate the importance of the ubiquitin-proteasome pathway, which has been suggested to be the main degradative pathway mediating progressive protein loss in cachexia, the expression of mRNA for proteasome subunits C2 and C5 as well as the ubiquitin-conjugating enzyme, E214k, has been determined in gastrocnemius and pectoral muscles of mice bearing the MAC16 adenocarcinoma, using competitive quantitative reverse transcriptase polymerase chain reaction. Protein levels of proteasome subunits and E214k were determined by immunoblotting, to ensure changes in mRNA were reflected in changes in protein expression. Muscle weights correlated linearly with weight loss during the course of the study. There was a good correlation between expression of C2 and E214k mRNA and protein levels in gastrocnemius muscle with increases of 6–8-fold for C2 and two-fold for E214k between 12 and 20% weight loss, followed by a decrease in expression at weight losses of 25–27%, although loss of muscle protein continued. In contrast, expression of C5 mRNA only increased two-fold and was elevated similarly at all weight losses between 7.5 and 27%. Both proteasome functional activity, and proteasome-specific tyrosine release as a measure of total protein degradation was also maximal at 18–20% weight loss and decreased at higher weight loss. Proteasome expression in pectoral muscle followed a different pattern with increases in C2 and C5 and E214k mRNA only being seen at weight losses above 17%, although muscle loss increased progressively with increasing weight loss. These results suggest that activation of the ubiquitin-proteasome pathway plays a major role in protein loss in gastrocnemius muscle, up to 20% weight loss, but that other factors such as depression in protein synthesis may play a more important role at higher weight loss

Practice Nurses' views of their role in the management of Chronic Fatigue Syndrome/Myalagic Encephalitis: a qualitative study

<p>Abstract</p> <p>Background</p> <p>NICE guidelines suggest that patients with Chronic Fatigue Syndrome/Myalgic Encephalitis (CFS/ME) should be managed in Primary Care. Practice Nurses are increasingly being involved in the management of long-term conditions, so are likely to also have a growing role in managing CFS/ME. However their attitudes to, and experiences of patients with CFS/ME and its management must be explored to understand what barriers may exist in developing their role for this group of patients. The aim of this study was to explore Practice Nurses' understanding and beliefs about CFS/ME and its management.</p> <p>Methods</p> <p>Semi-structured interviews with 29 Practice Nurses. Interviews were transcribed verbatim and an iterative approach used to develop themes from the dataset.</p> <p>Results</p> <p>Practice nurses had limited understanding about CFS/ME which had been largely gained through contact with patients, friends, personal experiences and the media rather than formal training. They had difficulty seeing CFS/ME as a long term condition. They did identify a potential role they could have in management of CFS/ME but devalued their own skills in psychological intervention, and suggested counselling would be an appropriate therapeutic option. They recognised a need for further training and on going supervision from both medical and psychological colleagues. Some viewed the condition as contentious and held pejorative views about CFS/ME. Such scepticism and negative attitudes will be a significant barrier to the management of patients with CFS/ME in primary care.</p> <p>Conclusion</p> <p>The current role of Practice Nurses in the ongoing management of patients with CFS/ME is limited. Practice Nurses have little understanding of the evidence-base for treatment of CFS/ME, particularly psychological therapies, describing management options in terms of advice giving, self-help or counselling. Practice Nurses largely welcomed the potential development of their role in this area, but identified barriers and training needs which must be addressed to enable them to feel confident managing of patients with this condition. Training must begin by addressing negative attitudes to patients with CFS/ME.</p

Discrete molecular dynamics can predict helical prestructured motifs in disordered proteins.

Intrinsically disordered proteins (IDPs) lack a stable tertiary structure, but their short binding regions termed Pre-Structured Motifs (PreSMo) can form transient secondary structure elements in solution. Although disordered proteins are crucial in many biological processes and designing strategies to modulate their function is highly important, both experimental and computational tools to describe their conformational ensembles and the initial steps of folding are sparse. Here we report that discrete molecular dynamics (DMD) simulations combined with replica exchange (RX) method efficiently samples the conformational space and detects regions populating alpha-helical conformational states in disordered protein regions. While the available computational methods predict secondary structural propensities in IDPs based on the observation of protein-protein interactions, our ab initio method rests on physical principles of protein folding and dynamics. We show that RX-DMD predicts alpha-PreSMos with high confidence confirmed by comparison to experimental NMR data. Moreover, the method also can dissect alpha-PreSMos in close vicinity to each other and indicate helix stability. Importantly, simulations with disordered regions forming helices in X-ray structures of complexes indicate that a preformed helix is frequently the binding element itself, while in other cases it may have a role in initiating the binding process. Our results indicate that RX-DMD provides a breakthrough in the structural and dynamical characterization of disordered proteins by generating the structural ensembles of IDPs even when experimental data are not available