Brachial plexopathy after prone positioning

Two cases of brachial plexus injury after prone position in the intensive care unit are described. Mechanisms of brachial plexus injury are described, as are methods for prevention of this unusual complication

Regulation of human Polλ by ATM-mediated phosphorylation during Non-Homologous End Joining

DNA double strand breaks (DSBs) trigger a variety of cellular signaling processes, collectively termed the DNA-damage response (DDR), that are primarily regulated by protein kinase ataxia-telangiectasia mutated (ATM). Among DDR activated processes, the repair of DSBs by non-homologous end joining (NHEJ) is essential. The proper coordination of NHEJ factors is mainly achieved through phosphorylation by an ATM-related kinase, the DNA-dependent protein kinase catalytic subunit (DNA-PKcs), although the molecular basis for this regulation has yet to be fully elucidated. In this study we identify the major NHEJ DNA polymerase, DNA polymerase lambda (Polλ), as a target for both ATM and DNA-PKcs in human cells. We show that Polλ is efficiently phosphorylated by DNA-PKcs in vitro and predominantly by ATM after DSB induction with ionizing radiation (IR) in vivo. We identify threonine 204 (T204) as a main target for ATM/DNA-PKcs phosphorylation on human Polλ, and establish that its phosphorylation may facilitate the repair of a subset of IR-induced DSBs and the efficient Polλ-mediated gap-filling during NHEJ. Molecular evidence suggests that Polλ phosphorylation might favor Polλ interaction with the DNA-PK complex at DSBs. Altogether, our work provides the first demonstration of how Polλ is regulated by phosphorylation to connect with the NHEJ core machinery during DSB repair in human cells.España MINECO y la Comisión Europea (European Regional Development Fund) to J.F.R. RYC-2011-08752, BFU2013-44343-P) and to F.C-L. (SAF2014-55532-R)

Structural accommodation of ribonucleotide incorporation by the DNA repair enzyme polymerase Mu

While most DNA polymerases discriminate against ribonucleotide triphosphate (rNTP) incorporation very effectively, the Family X member DNA polymerase μ (Pol μ) incorporates rNTPs almost as efficiently as deoxyribonucleotides. To gain insight into how this occurs, here we have used X-ray crystallography to describe the structures of pre- and post-catalytic complexes of Pol μ with a ribonucleotide bound at the active site. These structures reveal that Pol μ binds and incorporates a rNTP with normal active site geometry and no distortion of the DNA substrate or nucleotide. Moreover, a comparison of rNTP incorporation kinetics by wildtype and mutant Pol μ indicates that rNTP accommodation involves synergistic interactions with multiple active site residues not found in polymerases with greater discrimination. Together, the results are consistent with the hypothesis that rNTP incorporation by Pol μ is advantageous in gap-filling synthesis during DNA double strand break repair by nonhomologous end joining, particularly in nonreplicating cells containing very low deoxyribonucleotide concentrations

Nonhomologous end joining: A good solution for bad ends

Double strand breaks pose unique problems for DNA repair, especially when broken ends possess complex structures that interfere with standard DNA transactions. Nonhomologous end joining can use multiple strategies to solve these problems. It further uses sophisticated means to ensure the strategy chosen provides the ideal balance of flexibility and accuracy

Sustained active site rigidity during synthesis by human DNA polymerase μ

DNA polymerase mu (Pol μ) is the only template-dependent human DNA polymerase capable of repairing double strand DNA breaks (DSBs) with unpaired 3′-ends in non-homologous end joining (NHEJ). To probe this function, we structurally characterized Pol μ’s catalytic cycle for single nucleotide incorporation. These structures indicate that, unlike other template-dependent DNA polymerases, there are no large-scale conformational changes in protein subdomains, amino acid side chains, or DNA upon dNTP binding or catalysis. Instead, the only major conformational change is seen earlier in the catalytic cycle, when the flexible Loop1 region repositions upon DNA binding. Pol μ variants with changes in Loop1 have altered catalytic properties and are partially defective in NHEJ. The results indicate that specific Loop1 residues contribute to Pol μ’s unique ability to catalyze template-dependent NHEJ of DSBs with unpaired 3′-ends

Essential role for polymerase specialization in cellular nonhomologous end joining

Nonhomologous end joining (NHEJ) is a DNA double-strand break repair pathway required for development of the adaptive immune response, maintenance of cellular proliferative capacity, and the response to several commonly used cancer treatments. A major challenge faced by this pathway is that chromosome breaks can have dirty end structures, making them difficult to repair. We show here that two mammalian DNA polymerases have an unexpectedly pivotal role in helping resolve such ends. Each is proficient in different contexts and has a differing impact on repair fidelity. This work sheds light on how NHEJ has evolved to be flexible during repair and identifies two polymerases as critical for this process

Does Manual Therapy Provide Additional Benefit To Breathing Retraining In The Management Of Dysfunctional Breathing? A Randomised Controlled Trial

Purpose: Dysfunctional breathing (DB) is associated with an abnormal breathing pattern, unexplained breathlessness and significant patient morbidity. Treatment involves breathing retraining through respiratory physiotherapy. Recently, manual therapy (MT) has also been used, but no evidence exists to validate its use. This study sought to investigate whether MT produces additional benefit when compared with breathing retraining alone in patients with DB. Methods: Sixty subjects with primary DB were randomised into either breathing retraining (standard treatment; n¼30) or breathing retraining plus MT (intervention; n¼30) group. Both the groups received standardised respiratory physiotherapy, which included: DB education, breathing retraining, home regimen, and audio disc. Intervention group subjects additionally received MT following further assessment. Data from 57 subjects were analysed. Results: At baseline, standard treatment group subjects were statistically younger (41.7 + 13.5 versus 50.8 + 13.0 years; p¼0.001) with higher Nijmegen scores (38.6 + 9.5 versus 31.5 + 6.9; p¼0.001). However, no significant difference was found between the groups for primary outcome Nijmegen score (95% CI ( 1.1, 6.6) p¼0.162), or any secondary outcomes (Hospital Anxiety & Depression Score, spirometry or exercise tolerance). Conclusion: Breathing retraining is currently the mainstay of treatment for patients with DB. The results of this study suggest MT provides no additional benefit in this patient group.Juliana Burgess, Dr Robert Wilson, Royal Brompton & Harefield NHS Foundation Trust, and Dr Andy Jones fo

An Energy-Water Corridor Along the US/Mexico Border: Changing the \u27Conversation\u27

Over the last decade, migration has become a divisive issue around the world. A large number of countries have erected barriers along their borders to prevent migration, leading to geopolitical tension. Climate change effects will likely exacerbate migration tensions, which will require bold and creative solutions to this difficult social predicament. Here we detail a plan to construct an energy-water corridor along a border that has been the focus of much attention recently: The U.S.-Mexico border. Our proposed solution helps to alleviate some of the negative effects of climate change, while providing energy and economic stimulus to an area that begs for sustainable development. The energy-water corridor will take advantage of the unique renewable energy resources along the border states and will use state-of-the-art water desalination and treatment systems to provide the resources for economic development in the region

The fidelity of the ligation step determines how ends are resolved during nonhomologous end joining

Nonhomologous end joining (NHEJ) can effectively resolve chromosome breaks despite diverse end structures, but it is unclear how the steps employed for resolution are determined. We sought to address this question by analyzing cellular NHEJ of ends with systematically mispaired and damaged termini. We show NHEJ is uniquely proficient at bypassing subtle terminal mispairs and radiomimetic damage by direct ligation. Nevertheless, bypass ability varies widely, with increases in mispair severity gradually reducing bypass products from 85% to 6%. End-processing by nucleases and polymerases is increased to compensate, though paths with the fewest number of steps to generate a substrate suitable for ligation are favored. Thus, both the frequency and nature of end processing are tailored to meet the needs of the ligation step. We propose a model where the ligase organizes all steps during NHEJ within the stable paired-end complex to limit end processing and associated errors

Heat Safety in the Workplace:Modified Delphi Consensus to Establish Strategies and Resources to Protect U.S Workers

The purpose of this consensus document was to develop feasible, evidence‐based occupational heat safety recommendations to protect the US workers that experience heat stress. Heat safety recommendations were created to protect worker health and to avoid productivity losses associated with occupational heat stress. Recommendations were tailored to be utilized by safety managers, industrial hygienists, and the employers who bear responsibility for implementing heat safety plans. An interdisciplinary roundtable comprised of 51 experts was assembled to create a narrative review summarizing current data and gaps in knowledge within eight heat safety topics: (a) heat hygiene, (b) hydration, (c) heat acclimatization, (d) environmental monitoring, (e) physiological monitoring, (f) body cooling, (g) textiles and personal protective gear, and (h) emergency action plan implementation. The consensus‐based recommendations for each topic were created using the Delphi method and evaluated based on scientific evidence, feasibility, and clarity. The current document presents 40 occupational heat safety recommendations across all eight topics. Establishing these recommendations will help organizations and employers create effective heat safety plans for their workplaces, address factors that limit the implementation of heat safety best‐practices and protect worker health and productivity