Targeting the substrate preference of a type I nitroreductase to develop antitrypanosomal quinone-based prodrugs.

Nitroheterocyclic prodrugs are used to treat infections caused by Trypanosoma cruzi and Trypanosoma brucei. A key component in selectivity involves a specific activation step mediated by a protein homologous with type I nitroreductases, enzymes found predominantly in prokaryotes. Using data from determinations based on flavin cofactor, oxygen-insensitive activity, substrate range, and inhibition profiles, we demonstrate that NTRs from T. cruzi and T. brucei display many characteristics of their bacterial counterparts. Intriguingly, both enzymes preferentially use NADH and quinones as the electron donor and acceptor, respectively, suggesting that they may function as NADH:ubiquinone oxidoreductases in the parasite mitochondrion. We exploited this preference to determine the trypanocidal activity of a library of aziridinyl benzoquinones against bloodstream-form T. brucei. Biochemical screens using recombinant NTR demonstrated that several quinones were effective substrates for the parasite enzyme, having K(cat)/K(m) values 2 orders of magnitude greater than those of nifurtimox and benznidazole. In tests against T. brucei, antiparasitic activity mirrored the biochemical data, with the most potent compounds generally being preferred enzyme substrates. Trypanocidal activity was shown to be NTR dependent, as parasites with elevated levels of this enzyme were hypersensitive to the aziridinyl agent. By unraveling the biochemical characteristics exhibited by the trypanosomal NTRs, we have shown that quinone-based compounds represent a class of trypanocidal compound

Construction and in vivo assembly of a catalytically proficient and hyperthermostable de novo enzyme

Although catalytic mechanisms in natural enzymes are well understood, achieving the diverse palette of reaction chemistries in re-engineered native proteins has proved challenging. Wholesale modification of natural enzymes is potentially compromised by their intrinsic complexity, which often obscures the underlying principles governing biocatalytic efficiency. The maquette approach can circumvent this complexity by combining a robust de novo designed chassis with a design process that avoids atomistic mimicry of natural proteins. Here, we apply this method to the construction of a highly efficient, promiscuous, and thermostable artificial enzyme that catalyzes a diverse array of substrate oxidations coupled to the reduction of H2O2. The maquette exhibits kinetics that match and even surpass those of certain natural peroxidases, retains its activity at elevated temperature and in the presence of organic solvents, and provides a simple platform for interrogating catalytic intermediates common to natural heme-containing enzymes

Fundamental Limits on Wavelength, Efficiency and Yield of the Charge Separation Triad

In an attempt to optimize a high yield, high efficiency artificial photosynthetic protein we have discovered unique energy and spatial architecture limits which apply to all light-activated photosynthetic systems. We have generated an analytical solution for the time behavior of the core three cofactor charge separation element in photosynthesis, the photosynthetic cofactor triad, and explored the functional consequences of its makeup including its architecture, the reduction potentials of its components, and the absorption energy of the light absorbing primary-donor cofactor. Our primary findings are two: First, that a high efficiency, high yield triad will have an absorption frequency more than twice the reorganization energy of the first electron transfer, and second, that the relative distance of the acceptor and the donor from the primary-donor plays an important role in determining the yields, with the highest efficiency, highest yield architecture having the light absorbing cofactor closest to the acceptor. Surprisingly, despite the increased complexity found in natural solar energy conversion proteins, we find that the construction of this central triad in natural systems matches these predictions. Our analysis thus not only suggests explanations for some aspects of the makeup of natural photosynthetic systems, it also provides specific design criteria necessary to create high efficiency, high yield artificial protein-based triads

Cardiovascular risk factors are major determinants of thrombotic risk in patients with the lupus anticoagulant

BACKGROUND: Patients with the lupus anticoagulant (LA) are at an increased risk of thrombotic events, which in turn increase the risk of death. Understanding the determinants of thrombotic risk in patients with LA may pave the way towards targeted thromboprophylaxis. In the Vienna Lupus Anticoagulant and Thrombosis Study (LATS), we systematically evaluate risk factors for thrombotic events in patients with LA. METHODS: We followed 150 patients (mean age: 41.3 years, female gender: n = 122 (81.3%), history of thrombosis or pregnancy complications: n = 111 (74.0%)), who tested repeatedly positive for LA until development of thrombosis, death, or censoring. The primary endpoint was a composite of arterial or venous thrombotic events (TEs). RESULTS: During a median follow-up of 9.5 years (range: 12 days–13.6 years) and 1076 person-years, 32 TEs occurred (arterial: n = 16, venous: n = 16; cumulative 10-year TE incidence: 24.3%). A prolonged lupus-sensitive activated partial thromboplastin time (aPTT-LA) (adjusted subdistribution hazard ratio (SHR) = 2.31, 95% CI: 1.07–-5.02), diabetes (adjusted SHR = 4.39, 95% CI: 1.42–13.57), and active smoking (adjusted SHR = 2.31, 95% CI: 1.14–5.02) emerged as independent risk factors of both arterial and venous thrombotic risk. A risk model that includes a prolonged lupus-sensitive aPTT, smoking, and diabetes enabled stratification of LA patients into subgroups with a low, intermediate, and high risk of thrombosis (5-year TE risk of 9.7% (n = 77), 30.9% (n = 51), and 56.8% (n = 22). CONCLUSIONS: Long-term thrombotic risk in patients with LA is clustered within subjects harboring typical cardiovascular risk factors in addition to a prolonged lupus-sensitive aPTT, whereas patients with none of these risk factors represent a large subgroup with a low risk of thrombosis. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12916-017-0807-7) contains supplementary material, which is available to authorized users

Foundations for Open Scholarship Strategy Development, Version 2.1 [Pre-print]

This document aims to agree on a broad, international strategy for the implementation of open scholarship that meets the needs of different national and regional communities but works globally. Scholarly research can be idealised as an inspirational process for advancing our collective knowledge to the benefit of all humankind. However, current research practices often struggle with a range of tensions, in part due to the fact that this collective (or “commons”) ideal conflicts with the competitive system in which most scholars work, and in part because much of the infrastructure of the scholarly world is becoming largely digital. What is broadly termed as Open Scholarship is an attempt to realign modern research practices with this ideal. We do not propose a definition of Open Scholarship, but recognise that it is a holistic term that encompasses many disciplines, practices, and principles, sometimes also referred to as Open Science or Open Research. We choose the term Open Scholarship to be more inclusive of these other terms. When we refer to science in this document, we do so historically and use it as shorthand for more general scholarship. The purpose of this document is to provide a concise analysis of where the global Open Scholarship movement currently stands: what the common threads and strengths are, where the greatest opportunities and challenges lie, and how we can more effectively work together as a global community to recognise and address the top strategic priorities. This document was inspired by the Foundations for OER Strategy Development and work in the FORCE11 Scholarly Commons Working Group, and developed by an open contribution working group. Our hope is that this document will serve as a foundational resource for continuing discussions and initiatives about implementing effective strategies to help streamline the integration of Open Scholarship practices into a modern, digital research culture. Through this, we hope to extend the reach and impact of Open Scholarship into a global context, making sure that it is truly open for all. We also hope that this document will evolve as the conversations around Open Scholarship progress, and help to provide useful insight for both global co-ordination and local action. We believe this is a step forward in making Open Scholarship the norm. Ultimately, we expect the impact of widespread adoption of Open Scholarship to be diverse. We expect novel research practices to accelerate the pace of innovation, and therefore stimulate critical industries around the world. We could also expect to see an increase in public trust of science and scholarship, as transparency becomes more normative. As such, we expect interest in Open Scholarship to increase at multiple levels, due to its inherent influence on society and global economics

Open access policies of leading medical journals: a cross-sectional study

Objectives: Academic and not-for-profit research funders are increasingly requiring that the research they fund must be published open access, with some insisting on publishing with a Creative Commons Attribution (CC BY) licence to allow the broadest possible use. We set out to clarify the open access variants provided by leading medical journals for research in general and industry-funded research in particular, and record the availability of the CC BY licence for commercially funded research. Methods: We identified medical journals with a 2015 impact factor of at least 15.0 on 24 May 2017, then excluded from the analysis journals that only publish review articles. Between 29 June 2017 and 26 July 2017, we collected information about each journal's open access policies from their websites and/or by email contact. We contacted the journals by email again between 6 December 2017 and 2 January 2018 to confirm our findings. Results: Thirty-five medical journals publishing original research from 13 publishers were included in the analysis. All 35 journals offered some form of open access with varying embargo periods of up to 12 months. Of these journals, 21 (60%) provided immediate open access with a CC BY licence under certain circumstances (e.g. to specific research funders). Of these 21, 20 only offered a CC BY licence to authors funded by non-commercial organizations and one offered this option to funders who required it. Conclusions: Most leading medical journals do not offer to authors reporting commercially funded research an open access licence that allows unrestricted sharing and adaptation of the published material. The journals' policies are therefore not aligned with open access declarations and guidelines. Commercial research funders lag behind academic funders in the development of mandatory open access policies, and it is time for them to work with publishers to advance the dissemination of the research they fund.</jats:p

Innovative approaches to long term care

No abstract availabl