Time to peak effect of aspirin-induced platelet inhibition and ex vivo effects of desmopressin: An observational study

Objective: To investigate time to maximal platelet inhibition after an oral loading dose of ASA. The effect of ex vivo reversal platelet inhibition by desmopressin (DDAVP) was also studied. Methods: Ten healthy volunteers were given a 300 mg ASA-tablet. Blood was sampled at 0, 15, 30, 60, 120 and 180 minutes. DDAVP was added to the samples taken at 120 minutes. Samples were analysed with a Multiplate® platelet aggregometer (MEA) using arachidonic acid (AA), collagen and thrombin aggregation agonists. Results: Platelet inhibition was observed in the sample activated by AA at 15 minutes but not until 120 minutes in the samples activated by collagen. No platelet inhibition was seen in the samples activated by thrombin. The median time to maximal AA-induced platelet inhibition of <30 U was 30 (interquartile range 15-90) minutes. Ex vivo DDAVP did not reverse platelet inhibition. Subgroup analysis did not show any gender differences. Conclusions: ASA induces a strong platelet inhibition within 30 minutes of oral ingestion, with no gender differences. Ex vivo DDAVP did not reverse ASA’s platelet inhibition

Lattice Study of Anisotropic QED-3

We present results from a Monte Carlo simulation of non-compact lattice QED in 3 dimensions on a $16^3$ lattice in which an explicit anisotropy between $x$ and $y$ hopping terms has been introduced into the action. This formulation is inspired by recent formulations of anisotropic QED$_3$ as an effective theory of the non-superconducting portion of the cuprate phase diagram, with relativistic fermion degrees of freedom defined near the nodes of the gap function on the Fermi surface, and massless photon degrees of freedom reproducing the dynamics of the phase disorder of the superconducting order parameter. Using a parameter set corresponding to broken chiral symmetry in the isotropic limit, our results show that the renormalised anisotropy, defined in terms of the ratio of correlation lengths of gauge invariant bound states in the $x$ and $y$ directions, exceeds the explicit anisotropy $\kappa$ introduced in the lattice action, implying in contrast to recent analytic results that anisotropy is a relevant deformation of QED$_3$. There also appears to be a chiral symmetry restoring phase transition at $\kappa_c\simeq4.5$, implying that the pseudogap phase persists down to T=0 in the cuprate phase diagram.Comment: 24 pages, 9 figures, 3 tables. This (the published version) has the following alterations: i) An expanded discussion of the empirical aspects of HT superconductivity, ii) An updated version of Figure 4, iii) The removal of the consistency check in section 3.3.1 for reasons of brevit

Smart screens for thyroid disrupting substances in the environment

The interaction of recombinant TR with TRE-containing double-stranded DNA duplexes was monitored using the electrophoretic shift assay (EMSA). A protein titration allowed the calculation of the K& of TR for DNA. This quantitation of the affinity of TR for DNA was subsequently measured in the presence of known T3 analogues, thus providing the basis of a TR-DNA binding assay.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Electrophysiological characterization of human stem cell-derived neurones and glia in models of neurodevelopmental and neurodegenerative diseases

Human pluripotent stem cell (hPSC)-derived neuronal and glial material presents a relatively new opportunity to model human neurophysiology in both health, and disease. Validation of regionally-defined hPSC-derived neurones and glia cultures thus represents the founding blocks of technology that aims to complement existing models. Principally, the relevance of in vitro hPSC-derived material is determined by how representative it is of native material, yet at present the physiology of these cells remains underexplored. Here, electrophysiology and pharmacology are used to functionally assess hPSC-derived excitatory cortical neurones (hECNs), motorneurones (MNs) and oligodendrocyte-lineage cells in the context of regional-specific properties and maturation. These properties are then examined in material derived from hPSCs generated from patients with neurological disorders. This thesis examines of the properties of GABAARs and strychnine-sensitive glycine receptors (GlyRs) in hECNs by assessing their subunit composition, and compares these with studies which have made comparable investigations of rodent tissue where maturation is associated with a shift in GABAA and GlyR compositions. Using pharmacology and RNAseq analysis, GABAAR and GlyRs in hECNs were found to possess receptor populations typical of those reported in the immature cortex. hECNs generated from patients harbouring a mutation to the Disrupted-in-schizophrenia-gene 1 (DISC1), a candidate schizophrenia gene, were then examined. Imbalances in the excitation/inhibition balance are suspected in schizophrenia and, in this regard, the intrinsic excitability properties alongside expression and composition of major neurotransmitter receptors and intracellular chloride concentration were assessed. No obvious differences in excitability or functional expression of AMPARs, GABAARs or NMDARs were observed between case and control derived neurones. Receptor composition and intracellular chloride concentrations were found to be predominantly immature-like, however, AMPAR composition and intracellular chloride concentration were found to be like that of adult cortical neurones. These data are discussed in the context of modelling DISC1-associated pathologies. Thirdly, MNs from hPSCs generated from ALS patients harbouring mutations on the C9ORF72 gene were examined. The hypothesis that increased glutamate-mediated excitoxicity could, in part, be explained by increased expression of Ca2+- permeable AMPARs was examined. The estimated mean single-channel conductance of AMPARs was found to be high in MNs derived from ALS patients, reminiscent of Ca2+-permeable AMPARs and was reversed by gene-editing of the C9ORF72 mutation. Finally, oligodendrocytes generated from ALS patients harbouring TARDBP mutations were examined. Distinctive electrophysiological shifts in oligodendrocytes-lineage cell development are reported. A similar AMPAR phenotype of elevated Ca2+-permeable AMPAR expression was observed in oligodendrocytes derived from two patient hPSC lines and was rescued in an isogenic, gene-edited line, raising the intriguing possibility of convergence in pathophysiologies in the nature of the overlap between cell-type, AMPAR pathology and excitotoxicity in ALS disease progression mechanisms

Protamine dosage effects on complement activation and sonoclot coagulation analysis after cardiac surgery

Background: An optimal dosage and infusion regime for protamine reversal of heparin after cardiopulmonary bypass is important. Methods: Protamine dosages of either 2mg/kg or 4mg/kg bodyweight were compared in 40 patients after first time coronary arterial bypass grafting. Protamine was infused with a syringe driver over 20 minutes. Arterial blood sampling was performed prior to and during surgery, before and at 0.3, 0.6, 1, 3, 6 and 25h after the protamine infusion. C3a-desArg and C4a-desArg were analysed by radioimmunoassay. Coagulation was assayed with Sonoclot and activated clotting time. Results: Significantly higher inter-group plasma levels of C3a-desArg were seen with the greater protamine dose from 0.3- 0.6h, but none for C4a-desArg. Sonoclot parameters and leucocyte count differed significantly between the groups up to 6h, indicating hypercoagulabilty with the higher protamine dose. Significantly longer ACT in the low protamine dosage group indicited unblocked heparin with nonsignificant increased drainage bleeding and transfusions. There were no signs of allergic or anaphylactic reactions in any of the groups. Conclusion: Keeping the protamine dose low, minimizes complement activation with less viscoelastic signs of hypercoagulability. However there is an increased risk for drainage bleeding and unnecessary transfusion if heparin is not fully reversed with protamine post cardiopulmonary bypass. The present study was underpowered to detect significant differences in bleeding

Smart screens for thyroid disrupting substances in the environment

The interaction of recombinant TR with TRE-containing double-stranded DNA duplexes was monitored using the electrophoretic shift assay (EMSA). A protein titration allowed the calculation of the K& of TR for DNA. This quantitation of the affinity of TR for DNA was subsequently measured in the presence of known T3 analogues, thus providing the basis of a TR-DNA binding assay

Role of complement in tumour formation : Friend or foe?

The aims of this thesis were to investigate and build on recent reports implicating the complement (C) system in tumour growth and progression. The respective contributions of specific C components and regulators to this effect were assessed by the use of two tumour induction protocols. Firstly, the chemical carcinogen 3-methylcholanthrene (3-MCA) was used to induce tumours in wild type mice and in animals deficient in C1q, C3 or double deficient in CD55 and CD59. Deficiency in the classical pathway of activation (C1q"7') or in the central component (C3"7') conferred a statistically significant protective effect against 3-MCA-induced tumourigenesis, suggesting that a fully functional C system was important for promotion of tumour progression in vivo. Additionally, a protective effect was observed in CD55"7".CD59"7' mice indicating an important role for C-regulatory proteins (CRegs) in tumour progression. In the second approach, novel fibrosarcoma lines were generated from 3- MCA-induced tumours. WT, C1q"7", C3"7" and CDSS.CDS lines were cloned and tested for specific characteristics including CReg expression, synthesis of C3 and susceptibility to C-attack. Few differences were observed between lines of different genotypes though expression of terminal pathway regulator CD59 was observed in C3"7" lines only. Re-inoculation of WT and C3 lines showed no differences between the groups with comparable tumour incidence and growth rates observed. Additionally, the effect of C on progression of a pre-characterised WT fibrosarcoma line was tested by inoculation into WT and C-deficient mice. Tumours inoculated into C1q"7", C3"7" and CD55"7'.CD59"7" mice were shown to exhibit comparable growth characteristics to those in WT controls. However, depletion of the terminal pathway component C5 using a monoclonal antibody (mAb) was shown to inhibit tumour progression. Treatment of mice with anti- C5 mAb conferred a statistically significant protective effect to these mice and suggests a role for C in driving tumour pathology. In conclusion, work in this thesis demonstrates an important pro-tumour role for C whereby activation of C can result in enhanced tumour progression. Additionally, expression of the CRegs CD55 and CD59 on host cells rather than tumour cells contributes to tumour proliferation. A pro-tumour role for C is contrary to current dogma but supports an alternative hypothesis whereby cell activating effects may provide a selective advantage to tumour cells following C-activation