Mechanisms of translation arrest following focal brain ischemia

MECHANISMS OF TRANSLATION ARREST FOLLOWING FOCAL BRAIN ISCHEMIA by MONIQUE K. LEWIS August 2011 Advisor: Dr. Donald DeGracia Major: Physiology Degree: Doctor of Philosophy The loss of blood flow to the brain is termed ischemia and the subsequent resumption of blood flow is termed reperfusion. Brain ischemia and reperfusion (I/R) occurs primarily following resuscitation from cardiac arrest and stroke and presents one of the most significant clinical challenges. At present, there are no clinically effective pharmacologic interventions to halt brain damage following I/R. The major Aim of this dissertation will be to investigate possible mechanisms involved in neuron death following brain I/R, which may potentially lead to the development of effective therapies. A second major facet of this dissertation will be to address the issue of stroke and diabetes. It is very well established clinically that stroke outcome in diabetic patients is significantly worse than in non-diabetic patients. Diabetes has negative effects throughout the whole body and multiple different causes have been attributed to worsened stroke outcome. As both diabetes and stroke are stress to cells, I will hypothesize that the worsened damage is due to a cumulative or additive effect of each condition on neuronal stress responses. Neuronal death following brain I/R injury is a result of a variety of damage pathways. The focus of the work here is on a single feature of I/R injury: the persistent inhibition of protein synthesis, or translation arrest (TA), which occurs in neurons in response to I/R injury. TA is of significance because, as I discuss in detail below, it correlates with neuronal death. The purpose of this Dissertation is to investigate mechanisms of TA in the brain following focal ischemia, with and without diabetes. There has been extensive research on persistent TA in global models of brain I/R, whereas research in focal ischemia, as occurs in stroke, has not been as extensive. Therefore, there is a need to further study mechanisms of TA in the focal model. After a thorough literature review, I have found no studies of the possible role of TA in worsened stroke outcome in diabetics, making this line of investigation completely novel. Below, I will review our current understanding of I/R brain injury and how diabetes worsens outcome. I will discuss clinical outcomes, the major mechanisms, and especially focus on TA following brain I/R. The most current ideas on TA link it to intracellular stress responses and the formation of subcellular particles involved in mRNA metabolism such as stress granules and mRNA granules. My Background discussion will lead to my hypotheses about mechanisms of prolonged TA following focal brain I/R and the possible effect of diabetes on these mechanisms. In subsequent chapters I will present my study designs and results. The Dissertation will close with a chapter discussing the significance of my finding in light of the existent literature and in terms of new ideas about cell injury dynamics that are being developed in our laboratory

Exploring new media technologies among young South African women

This article reflects on how the use of digitised communication and social media among young black South African women can be situated and assessed within the current context. The authors focus especially on nuanced explorations of “civic participation,” “empowerment” and “identity politics” in acknowledging the liberatory potential of young women’s use of information and communication technology (ICTs) and seeking to assess its effects in realistic ways. We therefore speculate about how the uses of ICTs can both open up new possibilities for activism and agency and reveal the difficult formation of what Nancy Fraser has called “subaltern counterpublics” (1992: 109–142) among socially marginalised young women.Department of HE and Training approved lis

Functional insights from the crystal structure of the N-terminal domain of the prototypical toll receptor.

Drosophila melanogaster Toll is the founding member of an important family of pathogen-recognition receptors in humans, the Toll-like receptor (TLR) family. In contrast, the prototypical receptor is a cytokine-like receptor for Spätzle (Spz) protein and plays a dual role in both development and immunity. Here, we present the crystal structure of the N-terminal domain of the receptor that encompasses the first 201 amino acids at 2.4 Å resolution. To our knowledge, the cysteine-rich cap adopts a novel fold unique to Toll-1 orthologs in insects and that is not critical for ligand binding. However, we observed that an antibody directed against the first ten LRRs blocks Spz signaling in a Drosophila cell-based assay. Supplemented by point mutagenesis and deletion analysis, our data suggests that the region up to LRR 14 is involved in Spz binding. Comparison with mammalian TLRs reconciles previous contradictory findings about the mechanism of Toll activation.This work is financed by the Wellcome Trust Award (RG47206). We thank Dr. Martin Moncrieffe for helpful discussions and Ms. Irina Ogay from the Baculovirus Facility, Department of Biochemistry, Cambridge, for protein expression. We are grateful to Dr. Katherine Stott, from the Biophysics Facility, for her aid with analytical ultracentrifugation. Thanks to Dr. Dimitri Chirdgaze, from the Crystallographic X-ray Facility, for his assistance. We are grateful to Prof. Abel Moreno for help with capillary crystallization. We thank the staff at beamlines IO3 at Diamond Light Source, England, and ID23EH1 at the ESRF, Grenoble, France, for help with the data collection.This is the final version of the article. It first appeared from Elsevier (Cell Press) via http://dx.doi.org/10.1016/j.str.2012.11.00

Journalistic Role Performance in Australia During the COVID-19 Pandemic:Events, Media Systems and Journalistic Practice

This study analyses data gathered as part of an international comparative study of journalistic role performance during the first year of the COVID-19 pandemic. We situate role performance at the intersection between anterior factors that shape journalistic decision-making and practice, and the contingent events and issues journalists are tasked with communicating. Based on this, we ground our analysis by considering (a) how news is shaped by media systems, and how Australia’s media system may be characterised; (b) studies of journalists’ work during previous health crises; and (c) analyses of media coverage of the COVID-19 pandemic. Our analysis focuses, firstly, on whether role performance in Australia’s 2020 news coverage was discernibly “consensus-based”; and, secondly, on whether there were any indicators of Australian coverage being “polarised” during this period. Our findings suggest role performance in 2020 was broadly reflective of a relative political consensus and that evidence of polarisation was limited. We find, nevertheless, that there were notable differences between different mediums and outlets, and reflect on factors that may have contributed to such differences. In light of this, we emphasise the importance of taking account of the relationship between local contexts and historical contingency in considering how role performances are produced.</p

A School Bus Routing Heuristic Algorithm Allowing Heterogeneous Fleets and Bus Stop Selection

This paper addresses a school bus routing problem formulated as a capacitated and time-constrained open vehicle routing problem with a heterogeneous fleet and single loads. This problem incorporates several realistic features, such as student eligibility, maximum walking distances, bus stop selection, maximum riding times, different types of buses, multistops, and bus dwell times. A heuristic algorithm based on an iterated local search approach is proposed for this problem. It determines the selection of bus stops from a set of potential stops, the assignment of students to the selected bus stops, and the routes along the selected bus stops. The main objectives are minimizing the number of buses used, the total student walking distance, and the total route journey time. Other aims are balancing route journey times between buses and minimizing the total number of empty seats. A set of 20 real-world problem instances are used to evaluate the performance of the algorithm. Results indicate that the algorithm finds high-quality solutions in very short amounts of computational time

A Raf-competitive K-Ras binder can fail to functionally antagonize signaling

Mutated in approximately 30% of human cancers, Ras GTPases are the most common drivers of oncogenesis and render tumors unresponsive to many standard therapies. Despite decades of research, no drugs directly targeting Ras are currently available. We have previously characterized a small protein antagonist of K-Ras, R11.1.6, and demonstrated its direct competition with Raf for Ras binding. Here we evaluate the effects of R11.1.6 on Ras signaling and cellular proliferation in a panel of human cancer cell lines. Through lentiviral transduction, we generated cell lines that constitutively or through induction with doxycycline express R11.1.6 or a control protein YW1 and show specific binding by R11.1.6 to endogenous Ras through microscopy and co-immunoprecipitation experiments. Genetically-encoded intracellular expression of this high-affinity Ras antagonist, however, fails to measurably disrupt signaling through either the MAPK or PI3K pathway. Consistently, cellular proliferation was unaffected as well. To understand this lack of signaling inhibition, we quantified the number of molecules of R11.1.6 expressed by the inducible cell lines and developed a simple mathematical model describing the competitive binding of Ras by R11.1.6 and Raf. This model supports a potential mechanism for the lack of biological effects that we observed, suggesting stoichiometric and thermodynamic barriers that should be overcome in pharmacological efforts to directly compete with downstream effector proteins localized to membranes at very high effective concentrations.National Institutes of Health (U.S.) (grant 5 -R01-CA096504 -15)Massachusetts Institute of Technology. Associate Director FundMassachusetts Institute of Technology. Frontier FundDavid H. Koch Institute for Integrative Cancer Research at MIT. (Support core Grant P30- CA14051)National Institute of General Medical Sciences (U.S.). Interdepartmental Biotechnology Training Program ([T32 GM008334-25)German Cancer Foundation (Mildred-Scheel fellowship)Massachusetts Institute of Technology. Ludwig Center for Cancer Researc

A heuristic algorithm for school bus routing with bus stop selection

In this paper a heuristic algorithm is proposed for a school bus routing problem which is formulated as a capacitated and time-constrained open vehicle routing problem with a homogeneous fleet and single loads. The algorithm determines the selection of bus stops from a set of potential stops, the assignment of students to the selected bus stops, and the routes along the selected bus stops. Its goals are to minimize the number of buses used, the total route journey time and the student walking distances. It also aims at balancing route journey times between buses. The performance of the algorithm is evaluated on a set of twenty real-world problem instances and compared against solutions achieved by a mixed integer programming model. Reported results indicate that the heuristic algorithm finds high-quality solutions in very short amounts of computational time

The Year of Care approach: developing a model and delivery programme for care and support planning in long term conditions within general practice

Background: People with long term conditions (LTCs) make most of the daily decisions and carry out the activities which affect their health and quality of life. Only a fraction of each contact with a health care professional (HCP) is spent supporting this. This paper describes how care and support planning (CSP) and an implementation framework to redesign services, were developed to address this in UK general practice. Focussed on what is important to each individual, CSP brings together traditional clinical issues and the person's lived experience in a solution focussed, forward looking conversation with an emphasis on 'people not diseases'. Methods: The components of CSP were developed in three health communities using diabetes as an exemplar. This model was extended and refined for other single conditions and multimorbidity across 40 sites and two nations, over 15 years. Working with local teams and communities the authors used theoretical models of care, implementation and spread, developing and tailoring training, support and resources to embed CSP as usual care, sharing learning across a community of practice. Results: The purpose, content, process, developmental hurdles and impact of this CSP model are described, alongside an implementation strategy. There is now a robust, reproducible five step model; preparation, conversation, recording, actions and review. Uniquely, preparation, involving information sharing with time for reflection, enables an uncluttered conversation with a professional focussed on what is important to each person. The components of the Year of Care House act as a checklist for implementation, a metaphor for their interdependence and a flexible framework. Spreading CSP involved developing exemplar practices and building capacity across local health communities. These reported improved patient experience, practitioner job satisfaction, health behaviours and outcomes, teamwork, practice organisation, resource use, and links with wider community activities. Conclusions: Tested in multiple settings, CSP is a reproducible and practical model of planned care applicable to all LTCs, with the capacity to be transformative for people with LTCs and health care professionals. It recaptures relational dimensions of care with transactional elements in the background. Options for applying this model and implementation framework at scale now need to be explored