Publications by authors named "McQuaid K"

We report a crystal structure at atomic resolution (0.9 Å) of a ruthenium complex bound to a consecutive DNA double mismatch, which results in a TA basepair with flipped out thymine, together with the formation of an adenine bulge. The structure shows a form of metalloinsertion interaction of the Λ-[Ru(phen)phi] (phi = 9,10-phenanthrenediimine) complex at the bulge site.

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The grooves of DNA provide recognition sites for many nucleic acid binding proteins and anticancer drugs such as the covalently binding cisplatin. Here we report a crystal structure showing, for the first time, groove selectivity by an intercalating ruthenium complex. The complex Λ-[Ru(phen) phi] , where phi=9,10-phenanthrenediimine, is bound to the DNA decamer duplex d(CCGGTACCGG) .

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Ruthenium(II) complexes [Ru(tap)(NN)] (tap = 1,4,5,8-tetraazaphenanthrene, NN = 11-cyano-dipyrido[3,2-:2',3'-]phenazine (11-CN-dppz) and 11,12-dicyano-dipyrido[3,2-:2',3'-]phenazine (11,12-CN-dppz)) feature the C≡N groups as infrared (IR)-active redox markers. They were studied by cyclic voltammetry, UV-vis, and IR spectroelectrochemistry (SEC), and density functional theory calculations to assign the four 1e reduction waves R1-R4 observed in dichloromethane. Generally, the NN ligands are reduced first (R1).

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Cancer is a major cause of morbidity and mortality among people with inflammatory bowel disease (IBD). Intestinal cancers may arise as a complication of IBD itself, while extra-intestinal cancers may arise due to some of the immunosuppressive therapies used to treat IBD. Colorectal cancer (CRC) and small bowel cancer risks remain elevated among persons with IBD as compared to age-and sex-matched members of the general population, and the lifetime risk of these cancers is strongly correlated to cumulative intestinal inflammatory burden.

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Abyssal seafloor communities cover more than 60% of Earth's surface. Despite their great size, abyssal plains extend across modest environmental gradients compared to other marine ecosystems. However, little is known about the patterns and processes regulating biodiversity or potentially delimiting biogeographical boundaries at regional scales in the abyss.

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There is a growing interest in the exploitation of deep-sea mineral deposits, particularly on the abyssal seafloor of the central Pacific Clarion-Clipperton Zone (CCZ), which is rich in polymetallic nodules. In order to effectively manage potential exploitation activities, a thorough understanding of the biodiversity, community structure, species ranges, connectivity, and ecosystem functions across a range of scales is needed. The benthic megafauna plays an important role in the functioning of deep-sea ecosystems and represents an important component of the biodiversity.

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Background And Aims: Patients with inflammatory bowel disease (IBD) are at risk of developing dysplasia. According to the Surveillance for Colorectal Endoscopic Neoplasia Detection and Management in Inflammatory Bowel Disease Patients: International Consensus Recommendations, "After complete removal of endoscopically resectable nonpolypoid dysplastic lesions, surveillance colonoscopy is suggested rather than colectomy." We sought to add data to the literature and hypothesized that the endoscopic resection of nonpolypoid colorectal dysplasia (NP-CRD) is safe and effective.

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The four natural DNA bases (A, T, G and C) associate in base pairs (A=T and G≡C), allowing the attached DNA strands to assemble into the canonical double helix of DNA (or duplex-DNA, also known as B-DNA). The intrinsic supramolecular properties of nucleobases make other associations possible (such as base triplets or quartets), which thus translates into a diversity of DNA structures beyond B-DNA. To date, the alphabet of DNA structures is ripe with approximately 20 letters (from A- to Z-DNA); however, only a few of them are being considered as key players in cell biology and, by extension, valuable targets for chemical biology intervention.

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The DNA G-quadruplex is known for forming a range of topologies and for the observed lability of the assembly, consistent with its transient formation in live cells. The stabilization of a particular topology by a small molecule is of great importance for therapeutic applications. Here, we show that the ruthenium complex Λ-[Ru(phen)(qdppz)] displays enantiospecific G-quadruplex binding.

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In order to mount an appropriate immune response to infection, the macrophage must alter its metabolism by increasing aerobic glycolysis and concomitantly decreasing oxidative phosphorylation; a process known as the Warburg effect. Consequently, lactate, the end-product of glycolysis, accumulates in the extracellular environment. The subsequent effect of lactate on surrounding macrophages is poorly understood.

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Background And Aims: Endoscopists experience upper extremity musculoskeletal injuries. The primary aim of this study was to compare distal upper extremity biomechanical risk factors during colonoscopy with established risk thresholds. Secondary aims were to determine which subtasks during colonoscopy are associated with the greatest risk and to evaluate an intervention to reduce risks.

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Sepsis results in various patient complications and is due to a heightened inflammatory response against infection. This condition requires further exploration of biomarkers. We employed an "in silico" method comprised of text-mining and additionally clinical validation through the Medical Information Mart for Intensive Care.

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Tuberculosis is the single biggest infectious killer in the world and presents a major global health challenge. Antimicrobial therapy requires many months of multiple drugs and incidences of drug resistant tuberculosis continues to rise. Consequently, research is now focused on the development of therapies to support the function of infected immune cells.

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Endoscopic mucosal resection (EMR) is standard treatment for large colorectal polyps. However, it is a specialized technique with limited data on the effectiveness of training methods to acquire this skill. The aim of this study was to evaluate the impact of observational training on EMR outcomes and competency in an early-stage endoscopist.

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A spectroscopic study of the interactions of Λ- and Δ-[Ru(phen)(dppz)] with i-motif DNA containing thymine loops of various lengths. In the presence of i-motifs, the luminescence of the Λ enantiomer was enhanced much more than the Δ. Despite this, the effect of each enantiomer on i-motif thermal stability was comparable.

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The current endoscope design is not ergonomic. There is a high prevalence of endoscopy-related injury reported in the literature, and studies have demonstrated high-risk biomechanical exposures during the performance of routine colonoscopy. Endoscopy ergonomics focuses on understanding the endoscopist's interaction with the endoscope and the endoscopy unit and re-designing these tasks to minimize the risk of endoscopy-related injury.

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Λ-[Ru(TAP)2(dppz)]2+ was crystallised with the G-quadruplex-forming heptamer d(TAGGGTT). Surprisingly, even though there are four unique binding sites, the complex is not in contact with any G-quartet surface. Two complexes stabilise cavities formed from terminal T·A and T·T mismatched pairs.

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By using X-ray crystallography, we show that the complexes Λ/Δ-[Ru(TAP) (11-CN-dppz)] (TAP=1,4,5,8-tetraazaphenanthrene, dppz=dipyridophenazine) bind DNA G-quadruplex in an enantiospecific manner that parallels the specificity of these complexes with duplex DNA. The Λ complex crystallises with the normally parallel stranded d(TAGGGTTA) tetraplex to give the first such antiparallel strand assembly in which syn-guanosine is adjacent to the complex at the 5' end of the quadruplex core. SRCD measurements confirm that the same conformational switch occurs in solution.

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Background: Characterization of colonic lesions in inflammatory bowel disease (IBD) remains challenging. We developed an endoscopic classification of visual characteristics to identify colitis-associated neoplasia using multimodal advanced endoscopic imaging (Frankfurt Advanced Chromoendoscopic IBD LEsions [FACILE] classification).

Methods: The study was conducted in three phases: 1) development - an expert panel defined endoscopic signs and predictors of dysplasia in IBD and, using multivariable logistic regression created the FACILE classification; 2) validation - using 60 IBD lesions from an image library, two assessments of diagnostic accuracy for neoplasia were performed and interobserver agreement between experts using FACILE was determined; 3) reproducibility - the reproducibility of the FACILE classification was tested in gastroenterologists, trainees, and junior doctors after completion of a training module.

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The new complexes [Ru(TAP) (11-CN-dppz)] , [Ru(TAP) (11-Br-dppz)] and [Ru(TAP) (11,12-diCN-dppz)] are reported. The addition of nitrile substituents to the dppz ligand of the DNA photo-oxidising complex [Ru(TAP) (dppz)] promote π-stacking interactions and ordered binding to DNA, as shown by X-ray crystallography. The structure of Λ-[Ru(TAP) (11-CN-dppz)] with the DNA duplex d(TCGGCGCCGA) shows, for the first time with this class of complex, a closed intercalation cavity with an AT base pair at the terminus.

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Background And Aims: Balancing the risks for thromboembolism and postpolypectomy bleeding in patients requiring anticoagulation and antiplatelet agents is challenging. We investigated the incidence and risk factors for postpolypectomy bleeding on anticoagulation, including heparin bridge and other antithrombotic therapy.

Methods: We performed a retrospective cohort and case control study at 2 tertiary-care medical centers from 2004 to 2012.

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