1,601 research outputs found

    The OXR domain defines a conserved family of eukaryotic oxidation resistance proteins

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    BACKGROUND: The NCOA7 gene product is an estrogen receptor associated protein that is highly similar to the human OXR1 gene product, which functions in oxidation resistance. OXR genes are conserved among all sequenced eukaryotes from yeast to humans. In this study we examine if NCOA7 has an oxidation resistance function similar to that demonstrated for OXR1. We also examine NCOA7 expression in response to oxidative stress and its subcellular localization in human cells, comparing these properties with those of OXR1. RESULTS: We find that NCOA7, like OXR1 can suppress the oxidative mutator phenotype when expressed in an E. coli strain that exhibits an oxidation specific mutator phenotype. Moreover, NCOA7's oxidation resistance function requires expression of only its carboxyl-terminal domain and is similar in this regard to OXR1. We find that, in human cells, NCOA7 is constitutively expressed and is not induced by oxidative stress and appears to localize to the nucleus following estradiol stimulation. These properties of NCOA7 are in striking contrast to those of OXR1, which is induced by oxidative stress, localizes to mitochondria, and appears to be excluded, or largely absent from nuclei. CONCLUSION: NCOA7 most likely arose from duplication. Like its homologue, OXR1, it is capable of reducing the DNA damaging effects of reactive oxygen species when expressed in bacteria, indicating the protein has an activity that can contribute to oxidation resistance. Unlike OXR1, it appears to localize to nuclei and interacts with the estrogen receptor. This raises the possibility that NCOA7 encodes the nuclear counterpart of the mitochondrial OXR1 protein and in mammalian cells it may reduce the oxidative by-products of estrogen metabolite-mediated DNA damage

    Distributed network organization underlying feeding behavior in the mollusk Lymnaea

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    The aim of the work reviewed here is to relate the properties of individual neurons to network organization and behavior using the feeding system of the gastropod mollusk, Lymnaea. Food ingestion in this animal involves sequences of rhythmic biting movements that are initiated by the application of a chemical food stimulus to the lips and esophagus. We investigated how individual neurons contribute to various network functions that are required for the generation of feeding behavior such as rhythm generation, initiation ('decision making'), modulation and hunger and satiety. The data support the view that feeding behavior is generated by a distributed type of network organization with individual neurons often contributing to more than one network function, sharing roles with other neurons. Multitasking in a distributed type of network would be 'economically' sensible in the Lymnaea feeding system where only about 100 neurons are available to carry out a variety of complex tasks performed by millions of neurons in the vertebrate nervous system. Having complementary and potentially alternative mechanisms for network functions would also add robustness to what is a 'noisy' network where variable firing rates and synaptic strengths are commonly encountered in electrophysiological recording experiments

    Cardiorespiratory comorbidity and postoperative complications following esophagectomy: a European multicenter cohort study

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    BACKGROUND: The impact of cardiorespiratory comorbidity on operative outcomes after esophagectomy remains controversial. This study investigated the effect of cardiorespiratory comorbidity on postoperative complications for patients treated for esophageal or gastroesophageal junction cancer. PATIENTS AND METHODS: A European multicenter cohort study from five high-volume esophageal cancer centers including patients treated between 2010 and 2017 was conducted. The effect of cardiorespiratory comorbidity and respiratory function upon postoperative outcomes was assessed. RESULTS: In total 1590 patients from five centers were included; 274 (17.2%) had respiratory comorbidity, and 468 (29.4%) had cardiac comorbidity. Respiratory comorbidity was associated with increased risk of overall postoperative complications, anastomotic leak, pulmonary complications, pneumonia, increased Clavien-Dindo score, and critical care and hospital length of stay. After neoadjuvant chemoradiotherapy, respiratory comorbidity was associated with increased risk of anastomotic leak [odds ratio (OR) 1.83, 95% confidence interval (CI) 1.11-3.04], pneumonia (OR 1.65, 95% CI 1.10-2.47), and any pulmonary complication (OR 1.52, 95% CI 1.04-2.22), an effect which was not observed following neoadjuvant chemotherapy or surgery alone. Cardiac comorbidity was associated with increased risk of cardiovascular and pulmonary complications, respiratory failure, and Clavien-Dindo score ≥ IIIa. Among all patients, forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) ratio > 70% was associated with reduced risk of overall postoperative complications, cardiovascular complications, atrial fibrillation, pulmonary complications, and pneumonia. CONCLUSIONS: The results of this study suggest that cardiorespiratory comorbidity and impaired pulmonary function are associated with increased risk of postoperative complications after esophagectomy performed in high-volume European centers. Given the observed interaction with neoadjuvant approach, these data indicate a potentially modifiable index of perioperative risk

    Mechanical activation of vinculin binding to talin locks talin in an unfolded conformation

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    The force-dependent interaction between talin and vinculin plays a crucial role in the initiation and growth of focal adhesions. Here we use magnetic tweezers to characterise the mechano-sensitive compact N-terminal region of the talin rod, and show that the three helical bundles R1-R3 in this region unfold in three distinct steps consistent with the domains unfolding independently. Mechanical stretching of talin R1-R3 enhances its binding to vinculin and vinculin binding inhibits talin refolding after force is released. Mutations that stabilize R3 identify it as the initial mechano-sensing domain in talin, unfolding at ~5 pN, suggesting that 5 pN is the force threshold for vinculin binding and adhesion progression

    DPD Quantification in Cardiac Amyloidosis A Novel Imaging Biomarker

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    OBJECTIVES: To assess whether single-photon emission computed tomography (SPECT/CT) quantification of bone scintigraphy would improve diagnostic accuracy and offer a means of quantifying amyloid burden. BACKGROUND: Transthyretin-related cardiac amyloidosis is common and can be diagnosed noninvasively using bone scintigraphy; interpretation, however, relies on planar images. SPECT/CT imaging offers 3-dimensional visualization. METHODS: This was a single-center, retrospective analysis of 99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid (DPD) scans reported using the Perugini grading system (0 = negative; 1 to 3 = increasingly positive). Conventional planar quantification techniques (heart/contralateral lung, and heart/whole-body retention ratios) were performed. Heart, adjacent vertebra, paraspinal muscle and liver peak standardized uptake values (SUVpeak) were recorded from SPECT/CT acquisitions. An SUV retention index was also calculated: (cardiac SUVpeak/vertebral SUVpeak) × paraspinal muscle SUVpeak. In a subgroup of patients, SPECT/CT quantification was compared with myocardial extracellular volume quantification by CT imaging (ECVCT). RESULTS: A total of 100 DPD scans were analyzed (patient age 84 ± 9 years; 52% male): 40 were Perugini grade 0, 12 were grade 1, 41 were grade 2, and 7 were grade 3. Cardiac SUVpeak increased from grade 0 to grade 2; however, it plateaued between grades 2 and 3 (p < 0.001). Paraspinal muscle SUVpeak increased with grade (p < 0.001), whereas vertebral SUVpeak decreased (p < 0.001). The composite parameter of SUV retention index overcame the plateauing of the cardiac SUVpeak and increased across all grades (p < 0.001). Cardiac SUVpeak correlated well (r2 = 0.73; p < 0.001) with ECVCT. Both the cardiac SUVpeak and SUV retention index had excellent diagnostic accuracy (area under the curve [AUC]: 0.999). The heart to contralateral lung ratio performed the best of the planar quantification techniques (AUC: 0.987). CONCLUSIONS: SPECT/CT quantification in DPD scintigraphy is possible and outperforms planar quantification techniques. Differentiation of Perugini grade 2 or 3 is confounded by soft tissue uptake, which can be overcome by a composite SUV retention index. This index can help in the diagnosis of cardiac amyloidosis and may offer a means of monitoring response to therapy

    In silico assessment of potential druggable pockets on the surface of α1-Antitrypsin conformers

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    The search for druggable pockets on the surface of a protein is often performed on a single conformer, treated as a rigid body. Transient druggable pockets may be missed in this approach. Here, we describe a methodology for systematic in silico analysis of surface clefts across multiple conformers of the metastable protein α1-antitrypsin (A1AT). Pathological mutations disturb the conformational landscape of A1AT, triggering polymerisation that leads to emphysema and hepatic cirrhosis. Computational screens for small molecule inhibitors of polymerisation have generally focused on one major druggable site visible in all crystal structures of native A1AT. In an alternative approach, we scan all surface clefts observed in crystal structures of A1AT and in 100 computationally produced conformers, mimicking the native solution ensemble. We assess the persistence, variability and druggability of these pockets. Finally, we employ molecular docking using publicly available libraries of small molecules to explore scaffold preferences for each site. Our approach identifies a number of novel target sites for drug design. In particular one transient site shows favourable characteristics for druggability due to high enclosure and hydrophobicity. Hits against this and other druggable sites achieve docking scores corresponding to a Kd in the µM–nM range, comparing favourably with a recently identified promising lead. Preliminary ThermoFluor studies support the docking predictions. In conclusion, our strategy shows considerable promise compared with the conventional single pocket/single conformer approach to in silico screening. Our best-scoring ligands warrant further experimental investigation

    P113 is a merozoite surface protein that binds the N terminus of Plasmodium falciparum RH5.

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    Invasion of erythrocytes by Plasmodium falciparum merozoites is necessary for malaria pathogenesis and is therefore a primary target for vaccine development. RH5 is a leading subunit vaccine candidate because anti-RH5 antibodies inhibit parasite growth and the interaction with its erythrocyte receptor basigin is essential for invasion. RH5 is secreted, complexes with other parasite proteins including CyRPA and RIPR, and contains a conserved N-terminal region (RH5Nt) of unknown function that is cleaved from the native protein. Here, we identify P113 as a merozoite surface protein that directly interacts with RH5Nt. Using recombinant proteins and a sensitive protein interaction assay, we establish the binding interdependencies of all the other known RH5 complex components and conclude that the RH5Nt-P113 interaction provides a releasable mechanism for anchoring RH5 to the merozoite surface. We exploit these findings to design a chemically synthesized peptide corresponding to RH5Nt, which could contribute to a cost-effective malaria vaccine

    Nuclear Factor Kappa B Activation Occurs in the Amnion Prior to Labour Onset and Modulates the Expression of Numerous Labour Associated Genes

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    Background: Prior to the onset of human labour there is an increase in the synthesis of prostaglandins, cytokines and chemokines in the fetal membranes, particular the amnion. This is associated with activation of the transcription factor nuclear factor kappa B (NFkB). In this study we characterised the level of NFkB activity in amnion epithelial cells as a measure of amnion activation in samples collected from women undergoing caesarean section at 39 weeks gestation prior to the onset of labour. Methodology/Principal Findings: We found that a proportion of women exhibit low or moderate NFkB activity while other women exhibit high levels of NFkB activity (n = 12). This activation process does not appear to involve classical pathways of NFkB activation but rather is correlated with an increase in nuclear p65-Rel-B dimers. To identify the full range of genes upregulated in association with amnion activation, microarray analysis was performed on carefully characterised nonactivated amnion (n = 3) samples and compared to activated samples (n = 3). A total of 919 genes were upregulated in response to amnion activation including numerous inflammatory genes such cyclooxygenase-2 (COX-2, 44-fold), interleukin 8 (IL-8, 6-fold), IL-1 receptor accessory protein (IL-1RAP, 4.5-fold), thrombospondin 1 (TSP-1, 3-fold) and, unexpectedly, oxytocin receptor (OTR, 24-fold). Ingenuity Pathway Analysis of the microarray data reveal the two main gene networks activated concurrently with amnion activation are i) cell death, cancer and morphology and ii) cell cycle, embryoni
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