1,003 research outputs found
The Wicked Machinery of Government: Malta and the Problems of Continuity under the New Model Administration
This is a study focused on the early years of British rule in Malta (1800-1813). It explores the application to the island of the “new model” of colonial government, one based on direct rule from London mediated by the continuation of existing laws and institutions. Systemic deficiencies are identified. These tended to undermine the effectiveness of direct British rule. This study also reveals, in the context of legal and constitutional continuity, unresolved tensions between modernity and tradition. The political stability of the island was damaged and the possibility of continued British possession was threatened
On waiting for something to happen
This paper seeks to examine two particular and peculiar practices in which the mediation of apparently direct encounters is made explicit and is systematically theorized: that of the psychoanalytic dialogue with its inward focus and private secluded setting, and that of theatre and live performance, with its public focus. Both these practices are concerned with ways in which “live encounters” impact on their participants, and hence with the conditions under which, and the processes whereby, the coming-together of human subjects results in recognizable personal or social change. Through the rudimentary analysis of two anecdotes, we aim to think these encounters together in a way that explores what each borrows from the other, the psychoanalytic in the theatrical, the theatrical in the psychoanalytic, figuring each practice as differently committed to what we call the “publication of liveness”. We argue that these “redundant” forms of human contact continue to provide respite from group acceptance of narcissistic failure in the post-democratic era through their offer of a practice of waiting
New Mechanics of Traumatic Brain Injury
The prediction and prevention of traumatic brain injury is a very important
aspect of preventive medical science. This paper proposes a new coupled
loading-rate hypothesis for the traumatic brain injury (TBI), which states that
the main cause of the TBI is an external Euclidean jolt, or SE(3)-jolt, an
impulsive loading that strikes the head in several coupled degrees-of-freedom
simultaneously. To show this, based on the previously defined covariant force
law, we formulate the coupled Newton-Euler dynamics of brain's micro-motions
within the cerebrospinal fluid and derive from it the coupled SE(3)-jolt
dynamics. The SE(3)-jolt is a cause of the TBI in two forms of brain's rapid
discontinuous deformations: translational dislocations and rotational
disclinations. Brain's dislocations and disclinations, caused by the
SE(3)-jolt, are described using the Cosserat multipolar viscoelastic continuum
brain model.
Keywords: Traumatic brain injuries, coupled loading-rate hypothesis,
Euclidean jolt, coupled Newton-Euler dynamics, brain's dislocations and
disclinationsComment: 18 pages, 1 figure, Late
The regulatory subunit of PKA-I remains partially structured and undergoes β-aggregation upon thermal denaturation
Background: The regulatory subunit (R) of cAMP-dependent protein kinase (PKA) is a modular flexible protein that responds with large conformational changes to the binding of the effector cAMP. Considering its highly dynamic nature, the protein is rather stable. We studied the thermal denaturation of full-length RIα and a truncated RIα(92-381) that contains the tandem cyclic nucleotide binding (CNB) domains A and B. Methodology/Principal Findings: As revealed by circular dichroism (CD) and differential scanning calorimetry, both RIα proteins contain significant residual structure in the heat-denatured state. As evidenced by CD, the predominantly α-helical spectrum at 25°C with double negative peaks at 209 and 222 nm changes to a spectrum with a single negative peak at 212-216 nm, characteristic of β-structure. A similar α→β transition occurs at higher temperature in the presence of cAMP. Thioflavin T fluorescence and atomic force microscopy studies support the notion that the structural transition is associated with cross-β-intermolecular aggregation and formation of non-fibrillar oligomers. Conclusions/Significance: Thermal denaturation of RIα leads to partial loss of native packing with exposure of aggregation-prone motifs, such as the B' helices in the phosphate-binding cassettes of both CNB domains. The topology of the β-sandwiches in these domains favors inter-molecular β-aggregation, which is suppressed in the ligand-bound states of RIα under physiological conditions. Moreover, our results reveal that the CNB domains persist as structural cores through heat-denaturation. © 2011 Dao et al
Power and the durability of poverty: a critical exploration of the links between culture, marginality and chronic poverty
A secondary RET mutation in the activation loop conferring resistance to vandetanib
Resistance to vandetanib, a type I RET kinase inhibitor, developed in a patient with metastatic lung adenocarcinoma harboring a CCDC6-RET fusion that initially exhibited a response to treatment. The resistant tumor acquired a secondary mutation resulting in a serine-to-phenylalanine substitution at codon 904 in the activation loop of the RET kinase domain. The S904F mutation confers resistance to vandetanib by increasing the ATP affinity and autophosphorylation activity of RET kinase. A reduced interaction with the drug is also observed in vitro for the S904F mutant by thermal shift assay. A crystal structure of the S904F mutant reveals a small hydrophobic core around F904 likely to enhance basal kinase activity by stabilizing an active conformer. Our findings indicate that missense mutations in the activation loop of the kinase domain are able to increase kinase activity and confer drug resistance through allosteric effects
Molecular Basis of Ligand Dissociation in β-Adrenergic Receptors
The important and diverse biological functions of β-adrenergic receptors (βARs) have promoted the search for compounds to stimulate or inhibit their activity. In this regard, unraveling the molecular basis of ligand binding/unbinding events is essential to understand the pharmacological properties of these G protein-coupled receptors. In this study, we use the steered molecular dynamics simulation method to describe, in atomic detail, the unbinding process of two inverse agonists, which have been recently co-crystallized with β1 and β2ARs subtypes, along four different channels. Our results indicate that this type of compounds likely accesses the orthosteric binding site of βARs from the extracellular water environment. Importantly, reconstruction of forces and energies from the simulations of the dissociation process suggests, for the first time, the presence of secondary binding sites located in the extracellular loops 2 and 3 and transmembrane helix 7, where ligands are transiently retained by electrostatic and Van der Waals interactions. Comparison of the residues that form these new transient allosteric binding sites in both βARs subtypes reveals the importance of non-conserved electrostatic interactions as well as conserved aromatic contacts in the early steps of the binding process
Origin of Polar Order in Dense Suspensions of Phototactic Micro-Swimmers
A main question for the study of collective motion in living organisms is the origin of orientational polar order, i.e., how organisms align and what are the benefits of such collective behaviour. In the case of micro-organisms swimming at a low Reynolds number, steric repulsion and long-range hydrodynamic interactions are not sufficient to explain a homogeneous polar order state in which the direction of motion is aligned. An external symmetry-breaking guiding field such as a mechanism of taxis appears necessary to understand this phonemonon. We have investigated the onset of polar order in the velocity field induced by phototaxis in a suspension of a motile micro-organism, the algae Chlamydomonas reinhardtii, for density values above the limit provided by the hydrodynamic approximation of a force dipole model. We show that polar order originates from a combination of both the external guiding field intensity and the population density. In particular, we show evidence for a linear dependence of a phototactic guiding field on cell density to determine the polar order for dense suspensions and demonstrate the existence of a density threshold for the origin of polar order. This threshold represents the density value below which cells undergoing phototaxis are not able to maintain a homogeneous polar order state and marks the transition to ordered collective motion. Such a transition is driven by a noise dominated phototactic reorientation where the noise is modelled as a normal distribution with a variance that is inversely proportional to the guiding field strength. Finally, we discuss the role of density in dense suspensions of phototactic micro-swimmers
Histone deacetylase 1 and 2 differentially regulate apoptosis by opposing effects on extracellular signal-regulated kinase 1/2
Histone deacetylases (HDACs) are epigenetic regulators that are important for the control of various pathophysiological events. We found that HDAC inhibitors completely abolished transforming growth factor-β1 (TGF-β1)-induced apoptosis in AML-12 and primary mouse hepatocytes. Expression of a dominant-negative mutant of HDAC1 or downregulation of HDAC1 by RNAi both suppressed TGF-β1-induced apoptosis. In addition, overexpression of HDAC1 enhanced TGF-β1-induced apoptosis, and the rescue of HDAC1 expression in HDAC1 RNAi cells restored the apoptotic response of cells to TGF-β1. These data indicate that HDAC1 functions as a proapoptotic factor in TGF-β1-induced apoptosis. In contrast, downregulation of HDAC2 by RNAi increased spontaneous apoptosis and markedly enhanced TGF-β1-induced apoptosis, suggesting that HDAC2 has a reciprocal role in controlling cell survival. Furthermore, inhibition of extracellular signal-regulated kinase 1/2 (ERK1/2) by MEK1 inhibitor PD98059 or expression of a kinase-dead mutant of MEK1 restored the apoptotic response to TGF-β1 in HDAC1 RNAi cells. Strikingly, HDAC2 RNAi caused an inhibition of ERK1/2, and the spontaneous apoptosis can be abolished by reactivation of ERK1/2. Taken together, our data demonstrate that HDAC1 and 2 reciprocally affect cell viability by differential regulation of ERK1/2; these observations provide insight into the roles and potential mechanisms of HDAC1 and 2 in apoptosis
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