120 research outputs found
Investigating the suitability of carbon nanotube reinforced polymer in transcatheter valve applications
The current delivery size of transcatheter aortic valves, limited by the thickness of their pericardial leaflets, correlates with a high prevalence of major vascular complications. Polyurethane valves can be developed to a fraction of the thickness of pericardial valves through the addition of carbon nanotubes to reinforce their leaflets. This study investigates the suitability of a novel carbon nanotube reinforced leaflet to reduce the delivery profile of transcatheter aortic valves. Carbon nanotube polyurethane composites were developed with thicknesses of 50 μm and their mechanical properties were determined in relation to various environmental effects. The composites demonstrated improvements to the material stiffness, particularly at increasing strain rates compared to the neat polymer. However, increasing nanotube concentrations significantly decreased the fatigue life of the composites. Key findings highlighted a potential for carbon nanotube reinforcement in valve replacement which experience very high strain rates during the cardiac cycle. Further testing is needed to achieve a strong nanotube-matrix interface which will prolong the cyclic fatigue life and further strengthen tensile properties. Testing on the durability and haemocompatibility of these composite heart valves are ongoing
Application of pharmacogenomics and bioinformatics to exemplify the utility of human <i>ex vivo</i> organoculture models in the field of precision medicine
Here we describe a collaboration between industry, the National Health Service (NHS) and academia that sought to demonstrate how early understanding of both pharmacology and genomics can improve strategies for the development of precision medicines. Diseased tissue ethically acquired from patients suffering from chronic obstructive pulmonary disease (COPD), was used to investigate inter-patient variability in drug efficacy using ex vivo organocultures of fresh lung tissue as the test system. The reduction in inflammatory cytokines in the presence of various test drugs was used as the measure of drug efficacy and the individual patient responses were then matched against genotype and microRNA profiles in an attempt to identify unique predictors of drug responsiveness. Our findings suggest that genetic variation in CYP2E1 and SMAD3 genes may partly explain the observed variation in drug response
The DUF1669 domain of FAM83 family proteins anchor casein kinase 1 isoforms
Members of the casein kinase 1 (CK1) family of serine-threonine protein kinases are implicated in the regulation of many cellular processes, including the cell cycle, circadian rhythms, and Wnt and Hedgehog signaling. Because these kinases exhibit constitutive activity in biochemical assays, it is likely that their activity in cells is controlled by subcellular localization, interactions with inhibitory proteins, targeted degradation, or combinations of these mechanisms. We identified members of the FAM83 family of proteins as partners of CK1 in cells. All eight members of the FAM83 family (FAM83A to FAM83H) interacted with the α and α-like isoforms of CK1; FAM83A, FAM83B, FAM83E, and FAM83H also interacted with the δ and ε isoforms of CK1. We detected no interaction between any FAM83 member and the related CK1γ1, CK1γ2, and CK1γ3 isoforms. Each FAM83 protein exhibited a distinct pattern of subcellular distribution and colocalized with the CK1 isoform(s) to which it bound. The interaction of FAM83 proteins with CK1 isoforms was mediated by the conserved domain of unknown function 1669 (DUF1669) that characterizes the FAM83 family. Mutations in FAM83 proteins that prevented them from binding to CK1 interfered with the proper subcellular localization and cellular functions of both the FAM83 proteins and their CK1 binding partners. On the basis of its function, we propose that DUF1669 be renamed the polypeptide anchor of CK1 domain
Parkin is activated by PINK1-dependent phosphorylation of ubiquitin at Serine<sup>65</sup>
We have previously reported that the Parkinson's disease-associated kinase PINK1 (PTEN-induced putative kinase 1) is activated by mitochondrial depolarization and stimulates the Parkin E3 ligase by phosphorylating Ser(65) within its Ubl (ubiquitin-like) domain. Using phosphoproteomic analysis, we identified a novel ubiquitin phosphopeptide phosphorylated at Ser(65) that was enriched 14-fold in HEK (human embryonic kidney)-293 cells overexpressing wild-type PINK1 stimulated with the mitochondrial uncoupling agent CCCP (carbonyl cyanide m-chlorophenylhydrazone), to activate PINK1, compared with cells expressing kinase-inactive PINK1. Ser(65) in ubiquitin lies in a similar motif to Ser(65) in the Ubl domain of Parkin. Remarkably, PlNK1 directly phosphorylates Ser(65) of ubiquitin in vitro. We undertook a series of experiments that provide striking evidence that Ser(65)-phosphorylated ubiquitin (ubiquitin(Phospho-Ser65)) functions as a critical activator of Parkin. First, we demonstrate that a fragment of Parkin lacking the Ubl domain encompassing Ser(65) (Delta Ubl-Parkin) is robustly activated by ubiquitin(Phospho-Ser65), but not by non-phosphorylated ubiquitin. Secondly, we find that the isolated Parkin Ubl domain phosphorylated at Ser(65) (Ubl(phospho-Ser65)) can also activate Delta Ubl-Parkin similarly to ubiquitin(PhosPh-Ser65). Thirdly, we establish that ubiquitin(PhosPh-Ser65), but not non-phosphorylated ubiquitin or Ubl(PhosPh-Ser65) activates full-length wild-type Parkin as well as the non-phosphorylatable S65A Parkin mutant. Fourthly, we provide evidence that optimal activation of full-length Parkin E3 ligase is dependent on PINK1-mediated phosphorylation of both Parkin at Ser(65) and ubiquitin at Ser(65), since only mutation of both proteins at Ser(65) completely abolishes Parkin activation. In conclusion, the findings of the present study reveal that PINK1 controls Parkin E3 ligase activity not only by phosphorylating Parkin at Ser(65), but also by phosphorylating ubiquitin at Ser(65). We propose that phosphorylation of Parkin at Ser(65) serves to prime the E3 ligase enzyme for activation by ubiquitin(PhosPh-Ser65), suggesting that small molecules that mimic ubiquitin(PhosPh-Ser65) could hold promise as novel therapies for Parkinson's disease
Physiologically based pharmacokinetic modeling of arterial – antecubital vein concentration difference
BACKGROUND: Modeling of pharmacokinetic parameters and pharmacodynamic actions requires knowledge of the arterial blood concentration. In most cases, experimental measurements are only available for a peripheral vein (usually antecubital) whose concentration may differ significantly from both arterial and central vein concentration. METHODS: A physiologically based pharmacokinetic (PBPK) model for the tissues drained by the antecubital vein (referred to as "arm") is developed. It is assumed that the "arm" is composed of tissues with identical properties (partition coefficient, blood flow/gm) as the whole body tissues plus a new "tissue" representing skin arteriovenous shunts. The antecubital vein concentration depends on the following parameters: the fraction of "arm" blood flow contributed by muscle, skin, adipose, connective tissue and arteriovenous shunts, and the flow per gram of the arteriovenous shunt. The value of these parameters was investigated using simultaneous experimental measurements of arterial and antecubital concentrations for eight solutes: ethanol, thiopental, (99)Tc(m)-diethylene triamine pentaacetate (DTPA), ketamine, D(2)O, acetone, methylene chloride and toluene. A new procedure is described that can be used to determine the arterial concentration for an arbitrary solute by deconvolution of the antecubital concentration. These procedures are implemented in PKQuest, a general PBPK program that is freely distributed . RESULTS: One set of "standard arm" parameters provides an adequate description of the arterial/antecubital vein concentration for ethanol, DTPA, thiopental and ketamine. A significantly different set of "arm" parameters was required to describe the data for D(2)O, acetone, methylene chloride and toluene – probably because the "arm" is in a different physiological state. CONCLUSIONS: Using the set of "standard arm" parameters, the antecubital vein concentration can be used to determine the whole body PBPK model parameters for an arbitrary solute without any additional adjustable parameters. Also, the antecubital vein concentration can be used to estimate the arterial concentration for an arbitrary input for solutes for which no arterial concentration data is available
Cell-derived extracellular vesicles can be used as a biomarker reservoir for glioblastoma tumor subtyping
Glioblastoma (GBM) is one of the most aggressive solid tumors for which treatment options and biomarkers are limited. Small extracellular vesicles (sEVs) produced by both GBM and stromal cells are central in the inter-cellular communication that is taking place in the tumor bulk. As tumor sEVs are accessible in biofluids, recent reports have suggested that sEVs contain valuable biomarkers for GBM patient diagnosis and follow-up. The aim of the current study was to describe the protein content of sEVs produced by different GBM cell lines and patient-derived stem cells. Our results reveal that the content of the sEVs mirrors the phenotypic signature of the respective GBM cells, leading to the description of potential informative sEV-associated biomarkers for GBM subtyping, such as CD44. Overall, these data could assist future GBM in vitro studies and provide insights for the development of new diagnostic and therapeutic methods as well as personalized treatment strategies
A mutant O-GlcNAcase enriches Drosophila developmental regulators
YesProtein O-GlcNAcylation is a reversible post-translational modification of serines/threonines on
nucleocytoplasmic proteins. It is cycled by the enzymes O-GlcNAc transferase (OGT) and O-GlcNAc hydrolase
(O-GlcNAcase or OGA). Genetic approaches in model organisms have revealed that protein O-GlcNAcylation is
essential for early embryogenesis. Drosophila melanogaster OGT/supersex combs (sxc) is a polycomb gene,
null mutants of which display homeotic transformations and die at the pharate adult stage. However, the identities
of the O-GlcNAcylated proteins involved, and the underlying mechanisms linking these phenotypes to embryonic
development, are poorly understood. Identification of O-GlcNAcylated proteins from biological samples is
hampered by the low stoichiometry of this modification and limited enrichment tools. Using a catalytically inactive
bacterial O-GlcNAcase mutant as a substrate trap, we have enriched the O-GlcNAc proteome of the developing
Drosophila embryo, identifying, amongst others, known regulators of Hox genes as candidate conveyors of OGT
function during embryonic development.Wellcome Trust Investigator Award (110061); MRC grant (MC_UU_12016/5); and Royal Society Research Grant
Coronin-1A Links Cytoskeleton Dynamics to TCRαβ-Induced Cell Signaling
Actin polymerization plays a critical role in activated T lymphocytes both in regulating T cell receptor (TCR)-induced immunological synapse (IS) formation and signaling. Using gene targeting, we demonstrate that the hematopoietic specific, actin- and Arp2/3 complex-binding protein coronin-1A contributes to both processes. Coronin-1A-deficient mice specifically showed alterations in terminal development and the survival of αβT cells, together with defects in cell activation and cytokine production following TCR triggering. The mutant T cells further displayed excessive accumulation yet reduced dynamics of F-actin and the WASP-Arp2/3 machinery at the IS, correlating with extended cell-cell contact. Cell signaling was also affected with the basal activation of the stress kinases sAPK/JNK1/2; and deficits in TCR-induced Ca2+ influx and phosphorylation and degradation of the inhibitor of NF-κB (IκB). Coronin-1A therefore links cytoskeleton plasticity with the functioning of discrete TCR signaling components. This function may be required to adjust TCR responses to selecting ligands accounting in part for the homeostasis defect that impacts αβT cells in coronin-1A deficient mice, with the exclusion of other lympho/hematopoietic lineages
HE-LHC: The High-Energy Large Hadron Collider – Future Circular Collider Conceptual Design Report Volume 4
In response to the 2013 Update of the European Strategy for Particle Physics (EPPSU), the Future Circular Collider (FCC) study was launched as a world-wide international collaboration hosted by CERN. The FCC study covered an energy-frontier hadron collider (FCC-hh), a highest-luminosity high-energy lepton collider (FCC-ee), the corresponding 100 km tunnel infrastructure, as well as the physics opportunities of these two colliders, and a high-energy LHC, based on FCC-hh technology. This document constitutes the third volume of the FCC Conceptual Design Report, devoted to the hadron collider FCC-hh. It summarizes the FCC-hh physics discovery opportunities, presents the FCC-hh accelerator design, performance reach, and staged operation plan, discusses the underlying technologies, the civil engineering and technical infrastructure, and also sketches a possible implementation. Combining ingredients from the Large Hadron Collider (LHC), the high-luminosity LHC upgrade and adding novel technologies and approaches, the FCC-hh design aims at significantly extending the energy frontier to 100 TeV. Its unprecedented centre-of-mass collision energy will make the FCC-hh a unique instrument to explore physics beyond the Standard Model, offering great direct sensitivity to new physics and discoveries
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