Introducing a true internal standard for the Comet assay to minimize intra- and inter-experiment variability in measures of DNA damage and repair

The Comet assay (CA) is a sensitive/simple measure of genotoxicity. However, many features of CA contribute variability. To minimize these, we have introduced internal standard materials consisting of ‘reference’ cells which have their DNA substituted with BrdU. Using a fluorescent anti-BrdU antibody, plus an additional barrier filter, comets derived from these cells could be readily distinguished from the ‘test’-cell comets, present in the same gel. In experiments to evaluate the reference cell comets as external and internal standards, the reference and test cells were present in separate gels on the same slide or mixed together in the same gel, respectively, before their co-exposure to X-irradiation. Using the reference cell comets as internal standards led to substantial reductions in the coefficient of variation (CoV) for intra- and inter-experimental measures of comet formation and DNA damage repair; only minor reductions in CoV were noted when the reference and test cell comets were in separate gels. These studies indicate that differences between individual gels appreciably contribute to CA variation. Further studies using the reference cells as internal standards allowed greater significance to be obtained between groups of replicate samples. Ultimately, we anticipate that development will deliver robust quality assurance materials for CA

Risk-factors associated with extremely high cardiovascular risk of mid- and long-term mortality following myocardial infarction: An analysis of the Hyperlipidaemia Therapy in tERtiary Cardiological cEnTer (TERCET) Registry

Introduction: Risk-factor identification and risk stratification are prerequisites to the effective primary and secondary prevention of cardiovascular disease (CVD). Patients at the highest risk benefit the most from the intensive risk-factor reduction. However, high-risk patients’ group is heterogeneous, and it is increasingly recognised that there is an 'extreme-risk' category of patients who may require particularly close attention and intensive therapeutic approach. The aim of this study was to identify subgroups of patients at the highest risk of death following myocardial infarction (MI) that might be considered as those at extremely high CVD risk. Methods: We used data from 19,582 participants of the Hyperlipidaemia Therapy in tERtiary Cardiological cEnTer (TERCET) Registry (NCT03065543) of patients with ischaemic heart disease in Poland from 2006-present. Characteristics of 13,052 patients with chronic coronary syndromes (CCS) were compared with those of 4,295 patients with myocardial infarction (STEMI and 48 NSTEMI). Multivariable logistic regression with stepwise backward elimination was used to identify risk factors associated with mortality in the 12-36 months following the index hospitalisation. Results: The mortality rates were significantly higher in patients after MI than in patients with CCS. In the multivariable analysis, the risk factors most strongly associated with 12-month mortality in patients after MI were left ventricular ejection fraction (LVEF) lower than 35% (hazard ratio [HR] 3.83, 95% confidence interval [CI] 3.14-4.67), age >75 years (HR 1.91, 95%CI 1.55-2.35), multivessel coronary artery disease (HR 1.61, 95%CI 1.30-1.99), atrial fibrillation (HR 1.53, 95%CI 55 1.21-1.94) diabetes mellitus (HR 1.35, 95%CI 1.11-1.64) and increased LDL-C (HR per 1 mmol/l 56 1.09, 95%CI 1.01-1.19) or creatinine levels (HR per 10 µmol/L 1.04, 95% CI 1.04-1.05). The risk factors that influenced mortality after 24-36 months were consistent with those after 12 months, with additional low haemoglobin (20-25% risk increase per 1 mmol reduction) and chronic obstructive pulmonary disease (65% risk increase after 36 months). Conclusions: In our large, single-centre real-world analysis we identified the patients with the highest risk of death who could probably benefit the most from the most intensive therapy, and hence should be considered to be an 'extreme risk' population

The Small RNA Teg41 Regulates Expression of the Alpha Phenol-Soluble Modulins and Is Required for Virulence in \u3ci\u3eStaphylococcus aureus\u3c/i\u3e

Small RNAs (sRNAs) remain an understudied class of regulatory molecules in bacteria in general and in Gram-positive bacteria in particular. In the major human pathogen Staphylococcus aureus, hundreds of sRNAs have been identified; however, only a few have been characterized in detail. In this study, we investigate the role of the sRNA Teg41 in S. aureus virulence. We demonstrate that Teg41, an sRNA divergently transcribed from the locus that encodes the cytolytic alpha phenolsoluble modulin (αPSM) peptides, plays a critical role in αPSM production. Overproduction of Teg41 leads to an increase in αPSM levels and a corresponding increase in hemolytic activity from S. aureus cells and cell-free culture supernatants. To identify regions of Teg41 important for its function, we performed an in silico RNA-RNA interaction analysis which predicted an interaction between the 3= end of Teg41 and the αPSM transcript. Deleting a 24-nucleotide region from the S. aureus genome, corresponding to the 3= end of Teg41, led to a 10-fold reduction in αPSM-dependent hemolytic activity and attenuation of virulence in a murine abscess model of infection. Restoration of hemolytic activity in the Teg41Δ3= strain was possible by expressing full-length Teg41 in trans. Restoration of hemolytic activity was also possible by expressing the 3= end of Teg41, suggesting that this region of Teg41 is necessary and sufficient for αPSMdependent hemolysis. Our results show that Teg41 is positively influencing αPSM production, demonstrating for the first time regulation of the αPSM peptides by an sRNA in S. aureus

Heavy-flavour and quarkonium production in the LHC era: from proton-proton to heavy-ion collisions

This report reviews the study of open heavy-flavour and quarkonium production in high-energy hadronic collisions, as tools to investigate fundamental aspects of Quantum Chromodynamics, from the proton and nucleus structure at high energy to deconfinement and the properties of the Quark-Gluon Plasma. Emphasis is given to the lessons learnt from LHC Run 1 results, which are reviewed in a global picture with the results from SPS and RHIC at lower energies, as well as to the questions to be addressed in the future. The report covers heavy flavour and quarkonium production in proton-proton, proton-nucleus and nucleus-nucleus collisions. This includes discussion of the effects of hot and cold strongly interacting matter, quarkonium photo-production in nucleus-nucleus collisions and perspectives on the study of heavy flavour and quarkonium with upgrades of existing experiments and new experiments. The report results from the activity of the SaporeGravis network of the I3 Hadron Physics programme of the European Union 7th Framework Programme

Centrality and transverse momentum dependence of elliptic flow of multi-strange hadrons and ϕ\phi meson in Au+Au collisions at sNN\sqrt{s_{NN}} = 200 GeV

We present high precision measurements of elliptic flow near midrapidity ($|y|<1.0$) for multi-strange hadrons and $\phi$ meson as a function of centrality and transverse momentum in Au+Au collisions at center of mass energy $\sqrt{s_{NN}}=$ 200 GeV. We observe that the transverse momentum dependence of $\phi$ and $\Omega$ $v_{2}$ is similar to that of $\pi$ and $p$, respectively, which may indicate that the heavier strange quark flows as strongly as the lighter up and down quarks. This observation constitutes a clear piece of evidence for the development of partonic collectivity in heavy-ion collisions at the top RHIC energy. Number of constituent quark scaling is found to hold within statistical uncertainty for both 0-30$\%$ and 30-80$\%$ collision centrality. There is an indication of the breakdown of previously observed mass ordering between $\phi$ and proton $v_{2}$ at low transverse momentum in the 0-30$\%$ centrality range, possibly indicating late hadronic interactions affecting the proton $v_{2}$.Comment: 7 pages and 4 figures, Accepted for publication in Physical Review Letter