DNA induces conformational changes in a recombinant human minichromosome maintenance complex

ATP-dependent DNA unwinding activity has been demonstrated for recombinant archaeal homohexameric minichromosome maintenance (MCM) complexes and their yeast heterohexameric counterparts, but in higher eukaryotes such as Drosophila, MCM-associated DNA helicase activity has only been observed in the context of a co-purified Cdc45-MCM-GINS (CMG) complex. Here we describe the production of recombinant human MCM complex (hMCM) in E. coli. This protein displays ATP hydrolysis activity and is capable of unwinding duplex DNA. Using single particle asymmetric electron microscopy reconstruction, we demonstrate recombinant hMCM forms a hexamer that undergoes a conformational change when bound to DNA. Recombinant hMCM produced without post-translational modifications is functional in vitro and provides an important tool for the biochemical reconstitution of the human replicative helicase

Antiemetics: American Society of Clinical Oncology focused guideline update

Purpose: To update a key recommendation of the American Society of Clinical Oncology antiemetic guideline. This update addresses the use of the oral combination of netupitant (a neurokinin 1 [NK1] receptor antagonist) and palonosetron (a 5-hydroxytryptamine-3 [5-HT3] receptor antagonist) for the prevention of acute and delayed nausea and vomiting in patients receiving chemotherapy. Methods: An update committee conducted a targeted systematic literature review and identified two phase III clinical trials and a randomized phase II dose-ranging study. Results: In one phase III trial, the oral combination of netupitant and palonosetron was associated with higher complete response rates (no emesis and no rescue medications) compared with palonosetron alone in patients treated with anthracycline plus cyclophosphamide chemotherapy (74% v 67% overall; P = .001). In another phase III trial, the oral combination of netupitant and palonosetron was safe and effective across multiple cycles of moderately or highly emetogenic chemotherapies. In the phase II dose-ranging study, each dose of netupitant (coadministered with palonosetron 0.50 mg) produced higher complete response rates than palonosetron alone among patients receiving cisplatin-based chemotherapy. The highest dose of netupitant (ie, 300 mg) was most effective. Recommendations: All patients who receive highly emetogenic chemotherapy regimens (including anthracycline plus cyclophosphamide) should be offered a three-drug combination of an NK1 receptor antagonist, a 5-HT3 receptor antagonist, and dexamethasone. The oral combination of netupitant and palonosetron plus dexamethasone is an additional treatment option in this setting. The remaining recommendations from the 2011 ASCO guideline are unchanged pending a full update. Additional information is available at www.asco.org/guidelines/antiemetics and www.asco.org/guidelineswiki

In Silico and Structural Analyses Demonstrate That Intrinsic Protein Motions Guide T Cell Receptor Complementarity Determining Region Loop Flexibility.

T-cell immunity is controlled by T cell receptor (TCR) binding to peptide major histocompatibility complexes (pMHCs). The nature of the interaction between these two proteins has been the subject of many investigations because of its central role in immunity against pathogens, cancer, in autoimmunity, and during organ transplant rejection. Crystal structures comparing unbound and pMHC-bound TCRs have revealed flexibility at the interaction interface, particularly from the perspective of the TCR. However, crystal structures represent only a snapshot of protein conformation that could be influenced through biologically irrelevant crystal lattice contacts and other factors. Here, we solved the structures of three unbound TCRs from multiple crystals. Superposition of identical TCR structures from different crystals revealed some conformation differences of up to 5 Å in individual complementarity determining region (CDR) loops that are similar to those that have previously been attributed to antigen engagement. We then used a combination of rigidity analysis and simulations of protein motion to reveal the theoretical potential of TCR CDR loop flexibility in unbound state. These simulations of protein motion support the notion that crystal structures may only offer an artifactual indication of TCR flexibility, influenced by crystallization conditions and crystal packing that is inconsistent with the theoretical potential of intrinsic TCR motions

Differential expression and distribution of placental glutathione peroxidases 1, 3 and 4 in normal and preeclamptic pregnancy

Preeclampsia is a pregnancy-specific condition affecting 2-7% of women and a leading cause of perinatal and maternal morbidity and mortality; it may also predispose the mother and fetus to increased risks of adult cardiovascular disease. The selenoprotein glutathione peroxidases (GPxs) have critical roles in regulating antioxidant status. Objectives, study design and main outcome measures: Immunohistochemical measurements of GPx 1, GPx3 and GPx4 protein expression were performed on samples taken from three standardised sampling sites between the cord insertion and the periphery of the placenta from 12 normotensive, and 12 preeclamptic women to establish if their expression differed between sampling sites. Total GPx activities were also examined from the three sampling sites of these placentae. Results: There were highly significant reductions in overall immunohistochemical staining of all 3 GPxs in the preeclampsia compared to normotensive placentae (GPx1: P = 0.016; GPx3: P = 0.003; GPx4: P < 0.001). Furthermore, graded differences in expression between the standardised placental sampling sites were also found for GPx3 (higher in the inner region, P = 0.05) and GPx4 (higher in the periphery, P = 0.02) but not GPx1. Placental GPx enzyme activity was also significantly reduced in tissue from preeclamptic women as compared to normotensive women (P = 0.007; the difference was more pronounced nearest the cord insertion). Conclusions: We have shown highly significant reductions in expression of all three major classes of GPx in placentae from women with preeclampsia, and distribution gradients in activity, which may relate to the differential oxygenation of regions of the placenta

Antiemetics: American Society of Clinical Oncology clinical practice guideline update

Purpose: To update the ASCO guideline for antiemetics in oncology. Methods: ASCO convened an Expert Panel and conducted a systematic review of the medical literature for the period of November 2009 to June 2016. Results: Forty-one publications were included in this systematic review. A phase III randomized controlled trial demonstrated that adding olanzapine to antiemetic prophylaxis reduces the likelihood of nausea among adult patients who are treated with high emetic risk antineoplastic agents. Randomized controlled trials also support an expanded role for neurokinin 1 receptor antagonists in patients who are treated with chemotherapy. Recommendation: Key updates include the addition of olanzapine to antiemetic regimens for adults who receive high-emetic-risk antineoplastic agents or who experience breakthrough nausea and vomiting; a recommendation to administer dexamethasone on day 1 only for adults who receive anthracycline and cyclophosphamide chemotherapy; and the addition of a neurokinin 1 receptor antagonist for adults who receive carboplatin area under the curve ≥ 4 mg/mL per minute or high-dose chemotherapy, and for pediatric patients who receive high-emetic-risk antineoplastic agents. For radiation-induced nausea and vomiting, adjustments were made to anatomic regions, risk levels, and antiemetic administration schedules. Rescue therapy alone is now recommended for low-emetic-risk radiation therapy. The Expert Panel reiterated the importance of using the most effective antiemetic regimens that are appropriate for antineoplastic agents or radiotherapy being administered. Such regimens should be used with initial treatment, rather than first assessing the patient’s emetic response with less-effective treatment. Additional information is available at www.asco.org/supportive-care-guidelines and www.asco.org/guidelineswiki

Search for single top quarks in the tau+jets channel using 4.8 fb−1^{-1} of ppˉp\bar{p} collision data

We present the first direct search for single top quark production using tau leptons. The search is based on 4.8 fb$^{-1}$ of integrated luminosity collected in $p\bar{p}$ collisions at $\sqrt{s}$=1.96 TeV with the D0 detector at the Fermilab Tevatron Collider. We select events with a final state including an isolated tau lepton, missing transverse energy, two or three jets, one or two of them $b$ tagged. We use a multivariate technique to discriminate signal from background. The number of events observed in data in this final state is consistent with the signal plus background expectation. We set in the tau+jets channel an upper limit on the single top quark cross section of \TauLimObs pb at the 95% C.L. This measurement allows a gain of 4% in expected sensitivity for the observation of single top production when combining it with electron+jets and muon+jets channels already published by the D0 collaboration with 2.3 fb$^{-1}$ of data. We measure a combined cross section of \SuperCombineXSall pb, which is the most precise measurement to date.Comment: 12 pages, 5 figure

Measurement of Z/gamma*+jet+X angular distributions in ppbar collisions at sqrt{s}=1.96 TeV

We present the first measurements at a hadron collider of differential cross sections for Z+jet+X production in delta phi(Z, jet), |delta y(Z, jet)| and |y_boost(Z, jet)|. Vector boson production in association with jets is an excellent probe of QCD and constitutes the main background to many small cross section processes, such as associated Higgs production. These measurements are crucial tests of the predictions of perturbative QCD and current event generators, which have varied success in describing the data. Using these measurements as inputs in tuning event generators will increase the experimental sensitivity to rare signals.Comment: Published in Physics Letters B 682 (2010), pp. 370-380. 15 pages, 6 figure

Search for the standard model Higgs boson in tau final states

We present a search for the standard model Higgs boson using hadronically decaying tau leptons, in 1 inverse femtobarn of data collected with the D0 detector at the Fermilab Tevatron ppbar collider. We select two final states: tau plus missing transverse energy and b jets, and tau+ tau- plus jets. These final states are sensitive to a combination of associated W/Z boson plus Higgs boson, vector boson fusion and gluon-gluon fusion production processes. The observed ratio of the combined limit on the Higgs production cross section at the 95% C.L. to the standard model expectation is 29 for a Higgs boson mass of 115 GeV.Comment: publication versio

Measurement of the ttbar Production Cross Section in ppbar Collisions at sqrt(s)=1.96 TeV using Lepton + Jets Events with Lifetime b-tagging

We present a measurement of the top quark pair ($t\bar{t}$) production cross section ($\sigma_{t\bar{t}}$) in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV using 230 pb$^{-1}$ of data collected by the D0 experiment at the Fermilab Tevatron Collider. We select events with one charged lepton (electron or muon), missing transverse energy, and jets in the final state. We employ lifetime-based b-jet identification techniques to further enhance the $t\bar{t}$ purity of the selected sample. For a top quark mass of 175 GeV, we measure $\sigma_{t\bar{t}}=8.6^{+1.6}_{-1.5}(stat.+syst.)\pm 0.6(lumi.)$ pb, in agreement with the standard model expectation.Comment: 7 pages, 2 figures, 3 tables Submitted to Phys.Rev.Let

Measurement of the ttbar Production Cross Section in ppbar Collisions at sqrt{s} = 1.96 TeV using Kinematic Characteristics of Lepton + Jets Events

We present a measurement of the top quark pair ttbar production cross section in ppbar collisions at a center-of-mass energy of 1.96 TeV using 230 pb**{-1} of data collected by the DO detector at the Fermilab Tevatron Collider. We select events with one charged lepton (electron or muon), large missing transverse energy, and at least four jets, and extract the ttbar content of the sample based on the kinematic characteristics of the events. For a top quark mass of 175 GeV, we measure sigma(ttbar) = 6.7 {+1.4-1.3} (stat) {+1.6- 1.1} (syst) +/-0.4 (lumi) pb, in good agreement with the standard model prediction.Comment: submitted to Phys.Rev.Let