45 research outputs found
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Real-space refinement in PHENIX for cryo-EM and crystallography.
This article describes the implementation of real-space refinement in the phenix.real_space_refine program from the PHENIX suite. The use of a simplified refinement target function enables very fast calculation, which in turn makes it possible to identify optimal data-restraint weights as part of routine refinements with little runtime cost. Refinement of atomic models against low-resolution data benefits from the inclusion of as much additional information as is available. In addition to standard restraints on covalent geometry, phenix.real_space_refine makes use of extra information such as secondary-structure and rotamer-specific restraints, as well as restraints or constraints on internal molecular symmetry. The re-refinement of 385 cryo-EM-derived models available in the Protein Data Bank at resolutions of 6 Å or better shows significant improvement of the models and of the fit of these models to the target maps
Detection and correction of underassigned rotational symmetry prior to structure deposition
An X-ray structural model can be reassigned to a higher symmetry space group using the presented framework if its noncrystallographic symmetry operators are close to being exact crystallographic relationships. About 2% of structures in the Protein Data Bank can be reclassified in this way
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Macromolecular structure determination using X-rays, neutrons and electrons: recent developments in Phenix.
Diffraction (X-ray, neutron and electron) and electron cryo-microscopy are powerful methods to determine three-dimensional macromolecular structures, which are required to understand biological processes and to develop new therapeutics against diseases. The overall structure-solution workflow is similar for these techniques, but nuances exist because the properties of the reduced experimental data are different. Software tools for structure determination should therefore be tailored for each method. Phenix is a comprehensive software package for macromolecular structure determination that handles data from any of these techniques. Tasks performed with Phenix include data-quality assessment, map improvement, model building, the validation/rebuilding/refinement cycle and deposition. Each tool caters to the type of experimental data. The design of Phenix emphasizes the automation of procedures, where possible, to minimize repetitive and time-consuming manual tasks, while default parameters are chosen to encourage best practice. A graphical user interface provides access to many command-line features of Phenix and streamlines the transition between programs, project tracking and re-running of previous tasks
Knockdown of interferon-induced transmembrane protein 1 (IFITM1) inhibits proliferation, migration, and invasion of glioma cells
Interferon-induced transmembrane protein 1 (IFITM1) has recently been identified as a new molecular marker in human colorectal cancer. However, its role in glioma carcinogenesis is not known. In this study, we demonstrated that suppression of IFITM1 expression significantly inhibited proliferation of glioma cells in a time-dependent manner. The growth inhibitory effect was mediated by cell cycle arrest. Furthermore, IFITM1 knockdown significantly inhibited migration and invasion of glioma cells, which could be attributed to decreased expression and enzymatic activity of matrix metalloproteinase 9. Taken together, these results suggest that IFITM1 is a potential therapeutic target for gliomas
Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study
Background Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide.Methods A multimethods analysis was performed as part of the GlobalSurg 3 study-a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital.Findings Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3.85 [95% CI 2.58-5.75]; p<0.0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63.0% vs 82.7%; OR 0.35 [0.23-0.53]; p<0.0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer.Interpretation Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised
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A More Automated Approach to Data Collection for Macromolecular Crystallography
With the advances in structure refinement software that can automatically solve structures and the increasing use of robotics at synchrotron beamlines, high throughput crystallography is becoming much more automated. However, one aspect of the process that still requires a certain level of human intervention is during data collection. Web-Ice (Gonzalez A, Moorhead P, McPhillips SE, Song J, Sharp K, Taylor JR, Adams PD, Sauter NK, and Soltis SM, (2008) J. Appl. Cryst. 41(1), in press), jointly developed at the Stanford Synchrotron Radiation Laboratory and the Lawrence Berkeley National Laboratory, aims to address this issue by providing beamline users with a unified, graphical user interface that couples the low level control of the beamline hardware with the processing software (LABELIT, DISTL, MOSFLM) responsible for converting raw diffraction images into data sets suitable for refinement. Web-Ice can also perform automated crystal screening for selecting the best samples and calculation of the optimal strategy for data collection. Recent developments in Web-Ice include automatic handling of ice rings at varying two theta angles, automatic selection of the appropriate space group, and automatic data integration and scaling. Through Web-Ice, the beamline user can be more efficient at the synchrotron by allowing the software to handle the decision making for data collection in routine cases, while retaining the flexibility for more difficult data sets by providing a more user friendly interface for tweaking various parameters and customization of scripts for the data processing software