2,572 research outputs found

    Megahertz serial crystallography

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    The new European X-ray Free-Electron Laser is the first X-ray free-electron laser capable of delivering X-ray pulses with a megahertz inter-pulse spacing, more than four orders of magnitude higher than previously possible. However, to date, it has been unclear whether it would indeed be possible to measure high-quality diffraction data at megahertz pulse repetition rates. Here, we show that high-quality structures can indeed be obtained using currently available operating conditions at the European XFEL. We present two complete data sets, one from the well-known model system lysozyme and the other from a so far unknown complex of a β-lactamase from K. pneumoniae involved in antibiotic resistance. This result opens up megahertz serial femtosecond crystallography (SFX) as a tool for reliable structure determination, substrate screening and the efficient measurement of the evolution and dynamics of molecular structures using megahertz repetition rate pulses available at this new class of X-ray laser source

    Rapid sample delivery for megahertz serial crystallography at X-ray FELs

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    Liquid microjets are a common means of delivering protein crystals to the focus of X-ray free-electron lasers (FELs) for serial femtosecond crystallography measurements. The high X-ray intensity in the focus initiates an explosion of the microjet and sample. With the advent of X-ray FELs with megahertz rates, the typical velocities of these jets must be increased significantly in order to replenish the damaged material in time for the subsequent measurement with the next X-ray pulse. This work reports the results of a megahertz serial diffraction experiment at the FLASH FEL facility using 4.3 nm radiation. The operation of gas-dynamic nozzles that produce liquid microjets with velocities greater than 80 m s1 was demonstrated. Furthermore, this article provides optical images of X-ray-induced explosions together with Bragg diffraction from protein microcrystals exposed to trains of X-ray pulses repeating at rates of up to 4.5 MHz. The results indicate the feasibility for megahertz serial crystallography measurements with hard X-rays and give guidance for the design of such experiments.Unión Europea 7PM / 2007-2013Consejo de Investigación de Australia DP170100131Ministerio de Economía, Industria y Competitividad DPI2016-78887-C3-1-RNational Science Foundation "BioXFEL" (1231306

    Predicting serious complications in patients with cancer and pulmonary embolism using decision tree modelling: the EPIPHANY Index

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    Background: Our objective was to develop a prognostic stratification tool that enables patients with cancer and pulmonary embolism (PE), whether incidental or symptomatic, to be classified according to the risk of serious complications within 15 days. Methods: The sample comprised cases from a national registry of pulmonary thromboembolism in patients with cancer (1075 patients from 14 Spanish centres). Diagnosis was incidental in 53.5% of the events in this registry. The Exhaustive CHAID analysis was applied with 10-fold crossvalidation to predict development of serious complications following PE diagnosis. Results: About 208 patients (19.3%, 95% confidence interval (CI), 17.1-21.8%) developed a serious complication after PE diagnosis. The 15-day mortality rate was 10.1%, (95% CI, 8.4-12.1%). The decision tree detected six explanatory covariates: Hestia-like clinical decision rule (any risk criterion present vs none), Eastern Cooperative Group performance scale (ECOG-PS; = 2), O-2 saturation (= 90%), presence of PE-specific symptoms, tumour response (progression, unknown, or not evaluated vs others), and primary tumour resection. Three risk classes were created (low, intermediate, and high risk). The risk of serious complications within 15 days increases according to the group: 1.6, 9.4, 30.6%; P<0.0001. Fifteen-day mortality rates also rise progressively in low-, intermediate-, and high-risk patients: 0.3, 6.1, and 17.1%; P<0.0001. The cross-validated risk estimate is 0.191 (s.e. = 0.012). The optimism-corrected area under the receiver operating characteristic curve is 0.779 (95% CI, 0.717-0.840). Conclusions: We have developed and internally validated a prognostic index to predict serious complications with the potential to impact decision-making in patients with cancer and PE

    The presence of both HLA-DRB1[*]04:01 and HLA-B[*]15:01 increases the susceptibility to cranial and extracranial giant cell arteritis.

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    Objectives: To determine if patients with the predominant extracranial large-vessel-vasculitis (LVV) pattern of giant cell arteritis (GCA) have a distinctive HLA-B association, different from that reported in biopsy-proven cranial GCA patients. In a further step we assessed if the combination of HLA-B and HLA-DRB1 alleles confers an increased risk for GCA susceptibility, either for the cranial and extracranial LVV phenotypes. Methods: A total of 184 patients with biopsy-proven cranial GCA, 105 with LVV-GCA and 486 healthy controls were included in our study. We compared HLA-B phenotype frequencies between the three groups. Results: HLA-B*15 phenotype was significantly increased in patients with classic cranial GCA compared to controls (14.7% versus 5.8%, respectively; p<0.01; OR [95% CI] =2.81 [1.54-5.11]). It was mainly due to the HLA-B*15:01 allele (12.5% versus 4.0%, respectively; p<0.01; OR [95% CI] =3.51 [1.77-6.99]) and remained statistically significant after Bonferroni correction. Similar HLA-B*15 association was observed in patients with the LVV-GCA (11.4% versus 5.8%, p=0.04, OR [95% CI] =2.11 [1.04-4.30]). This association was also mainly due to the HLA-B*15:01 allele (10.5% versus 4.0%, respectively; p=0.0054; OR [95% CI] =2.88 [1.19-6.59]). Noteworthy, the presence of HLA-B*15:01 together with HLA-DRB1*04:01 led to an increased risk of developing both cranial and extracranial LVV-GCA. Conclusions: Susceptibility to GCA is strongly related to the HLA region, regardless of the clinical phenotype of expression of the disease.This work was partially supported by RETICS Programs, RD08/0075 (RIER), RD12/0009/0013 and RD16/0012 from ‘‘Instituto de Salud Carlos III’’ (ISCIII) (Spain). However, this research did not receive any specific grant from funding agencies in the commercial or not-for-profit sectors

    Oral fosfomycin for the treatment of lower urinary tract infections among kidney transplant recipients—Results of a Spanish multicenter cohort

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    Preliminary results of this study were presented at the 29th European Congress of Clinical Microbiology and Infectious Diseases (ECCMID), held in Amsterdam, The Netherlands, from 13 to 16 April, 2019 (oral communication O‐0699).Oral fosfomycin may constitute an alternative for the treatment of lower urinary tract infections (UTIs) in kidney transplant recipients (KTRs), particularly in view of recent safety concerns with fluroquinolones. Specific data on the efficacy and safety of fosfomycin in KTR are scarce. We performed a retrospective study in 14 Spanish hospitals including KTRs treated with oral fosfomycin (calcium and trometamol salts) for posttransplant cystitis between January 2005 and December 2017. A total of 133 KTRs developed 143 episodes of cystitis. Most episodes (131 [91.6%]) were produced by gram‐negative bacilli (GNB), and 78 (54.5%) were categorized as multidrug resistant (including extended‐spectrum β‐lactamase‐producing Enterobacteriaceae [14%] or carbapenem‐resistant GNB [3.5%]). A median daily dose of 1.5 g of fosfomycin (interquartile range [IQR]: 1.5‐2) was administered for a median of 7 days (IQR: 3‐10). Clinical cure (remission of UTI‐attributable symptoms at the end of therapy) was achieved in 83.9% (120/143) episodes. Among those episodes with follow‐up urine culture, microbiological cure at month 1 was achieved in 70.2% (59/84) episodes. Percutaneous nephrostomy was associated with a lower probability of clinical cure (adjusted odds ratio: 10.50; 95% confidence interval: 0.98‐112.29; P = 0.052). In conclusion, fosfomycin is an effective orally available alternative for treating cystitis among KTRs.This study was supported by Plan Nacional de I+D+i 2013‐2016 and Instituto de Salud Carlos III, Subdirección General de Redes y Centros de Investigación Cooperativa, Ministerio de Ciencia, Innovación y Universidades, Spanish Network for Research in Infectious Diseases (REIPI RD16/0016)—cofinanced by the European Development Regional Fund “A way to achieve Europe”; the Group for Study of Infection in Transplantation and the Immunocompromised Host (GESITRA‐IC) of the Spanish Society of Clinical Microbiology and Infectious Diseases (SEIMC); and the Spanish Network for Research in Renal Diseases (REDInREN RD16/0009). MFR holds a research contract “Miguel Servet” (CP 18/00073) from the Spanish Ministry of Science, Innovation and Universities, Instituto de Salud Carlos III

    Efficacy of Anakinra in Refractory Adult-Onset Still's Disease: Multicenter Study of 41 Patients and Literature Review

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    Adult-onset Still's disease (AOSD) is often refractory to standard therapy. Anakinra (ANK), an interleukin-1 receptor antagonist, has demonstrated efficacy in single cases and small series of AOSD. We assessed the efficacy of ANK in a series of AOSD patients. Multicenter retrospective open-label study. ANK was used due to lack of efficacy to standard synthetic immunosuppressive drugs and in some cases also to at least 1 biologic agent. Forty-one patients (26 women/15 men) were recruited. They had a mean age of 34.4 ± 14 years and a median [interquartile range (IQR)] AOSD duration of 3.5 [2-6] years before ANK onset. At that time the most common clinical features were joint manifestations 87.8%, fever 78%, and cutaneous rash 58.5%. ANK yielded rapid and maintained clinical and laboratory improvement. After 1 year of therapy, the frequency of joint and cutaneous manifestations had decreased to 41.5% and to 7.3% respectively, fever from 78% to 14.6%, anemia from 56.1% to 9.8%, and lymphadenopathy from 26.8% to 4.9%. A dramatic improvement of laboratory parameters was also achieved. The median [IQR] prednisone dose was also reduced from 20 [11.3-47.5] mg/day at ANK onset to 5 [0-10] at 12 months. After a median [IQR] follow-up of 16 [5-50] months, the most important side effects were cutaneous manifestations (n = 8), mild leukopenia (n = 3), myopathy (n = 1), and infections (n = 5). ANK is associated with rapid and maintained clinical and laboratory improvement, even in nonresponders to other biologic agents. However, joint manifestations are more refractory than the systemic manifestations

    Differential branching fraction and angular analysis of the decay B0→K∗0μ+μ−

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    The angular distribution and differential branching fraction of the decay B 0→ K ∗0 μ + μ − are studied using a data sample, collected by the LHCb experiment in pp collisions at s√=7 TeV, corresponding to an integrated luminosity of 1.0 fb−1. Several angular observables are measured in bins of the dimuon invariant mass squared, q 2. A first measurement of the zero-crossing point of the forward-backward asymmetry of the dimuon system is also presented. The zero-crossing point is measured to be q20=4.9±0.9GeV2/c4 , where the uncertainty is the sum of statistical and systematic uncertainties. The results are consistent with the Standard Model predictions

    Search for the lepton-flavor-violating decays Bs0→e±μ∓ and B0→e±μ∓

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    A search for the lepton-flavor-violating decays Bs0→e±μ∓ and B0→e±μ∓ is performed with a data sample, corresponding to an integrated luminosity of 1.0  fb-1 of pp collisions at √s=7  TeV, collected by the LHCb experiment. The observed number of Bs0→e±μ∓ and B0→e±μ∓ candidates is consistent with background expectations. Upper limits on the branching fractions of both decays are determined to be B(Bs0→e±μ∓)101  TeV/c2 and MLQ(B0→e±μ∓)>126  TeV/c2 at 95% C.L., and are a factor of 2 higher than the previous bounds

    Model-independent search for CP violation in D0→K−K+π−π+ and D0→π−π+π+π− decays

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    A search for CP violation in the phase-space structures of D0 and View the MathML source decays to the final states K−K+π−π+ and π−π+π+π− is presented. The search is carried out with a data set corresponding to an integrated luminosity of 1.0 fb−1 collected in 2011 by the LHCb experiment in pp collisions at a centre-of-mass energy of 7 TeV. For the K−K+π−π+ final state, the four-body phase space is divided into 32 bins, each bin with approximately 1800 decays. The p-value under the hypothesis of no CP violation is 9.1%, and in no bin is a CP asymmetry greater than 6.5% observed. The phase space of the π−π+π+π− final state is partitioned into 128 bins, each bin with approximately 2500 decays. The p-value under the hypothesis of no CP violation is 41%, and in no bin is a CP asymmetry greater than 5.5% observed. All results are consistent with the hypothesis of no CP violation at the current sensitivity
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