Characterizing RyR and SERCA function in the C57 and D2 mdx mouse models of Duchenne Muscular Dystrophy

Duchenne Muscular Dystrophy (DMD) is a male-affected muscle wasting disease caused by the complete loss of the sarcolemmal protein dystrophin. No cure exists and patients typically succumb to cardiorespiratory issues in the third or fourth decade of life. Dystrophin loss also leads to dysfunction in other pathways; including impaired sarcoplasmic reticulum (SR) calcium (Ca2+) handling, further perpetuating the disease. This thesis examined potential differences in SR Ca2+ handling in two mouse models of DMD. The D2.B10-Dmdmdx/J (D2 mdx) mouse has emerged as a more pathologically representative model of DMD than the C57BL/10ScSn-Dmdmdx/J (C57 mdx) mouse model, showing greater muscle weakness, wasting and earlier disease onset. However, SR Ca2+ has not yet been characterized in the D2 mdx mouse. Thus, the aim of this study was to compare SR Ca2+ handling in the D2 mdx and C57 mdx mice. Using age-matched (9-10 week-old) mice, we found that D2 mdx mice had less mass, smaller gastrocnemius muscles, and were less ambulant. The D2 mdx mice had significantly higher energy expenditure and respiratory exchange ratio compared with the D2 WT mice. Two separate SR Ca2+ uptake assays revealed that D2 mdx mice have less Ca2+ uptake and leak, and higher starting myoplasmic Ca2+. SERCA activity (ATP hydrolysis) was lower in D2 mdx mice while higher in C57 mdx mice. These dramatic impairments in SR Ca2+ handling were not attributed to differences in SERCA isoform content or changes in its regulator, sarcolipin. However, under reducing conditions, protein nitration and nitrosylation content were significantly higher in D2 mdx gastrocnemius muscles. Further, pre-treatment with dithiothreiotol (DTT) did not improve SR Ca2+ handling in these muscles, suggestive of irreversible reactive oxygen/nitrogen post-translational modifications. Finally, calpain proteolytic activity was examined to determine the consequence of the impaired SR Ca2+ handling in the D2 mdx mouse. While D2 WT mice already had higher levels of calpain activity, the D2 mdx mouse had significantly higher calpain activity vs the C57 mdx mouse. Altogether, the results from this thesis suggest that impaired SR Ca2+ handling may be partially responsible for more severe pathology found in the D2 mdx mice

Ghrelin Processing and Maturation: Developing a Molecular-Level Framework for Hormone Activation and Biological Function

Ghrelin is a 28 amino acid hormone involved in appetite stimulation, maintenance of energy balance, and a range of other neuroendocrine functions. Over the course of its expression and maturation, proghrelin (the prohormone of ghrelin) undergoes a unique posttranslational modification whereby a serine side chain is esterified with octanoic acid. Proghrelin then undergoes subsequent proteolysis to yield ghrelin. This octanoylation modification has been demonstrated to be required for ghrelin to activate its cognate receptor. Since acylated ghrelin has been linked with a variety of disease states, ghrelin signaling is a prime target for inhibition and inhibitor development. Biochemical and structural studies of the enzyme responsible for ghrelin octanoylation, ghrelin O-acyltransferase (GOAT), have identified features required for recognition of ghrelin by GOAT. A majority of these studies have utilized peptide mimetics of the N-terminal sequence of ghrelin. However, the impact of downstream elements in ghrelin and its 94 amino acid precursor proghrelin remains to be fully defined. To investigate this, we have developed bacterial expression systems to explore the role of both ghrelin and C-terminal ghrelin in proghrelin’s biological activity and maturation. The work presented in this dissertation is the first instance of expression and structural characterization of human proghrelin and C-ghrelin, as well as an unidentified self-cleavage behavior which has implications in hormone maturation. In complementary studies to characterize ghrelin binding to GOAT, ghrelin peptide mimetics incorporating an amine-substituted Dap residue at the site of acylation provided a superior system for exploring the molecular requirements for ghrelin recognition by GOAT. These studies have identified previously unidentified binding contacts and provides a comprehensive model of peptide binding in the hGOAT active site. The work utilizing Dap-substituted peptides provides a comprehensive peptide scaffold for future inhibitor design for targeting ghrelin signaling

THE EFFECTS OF FEDERAL LAND ON RURAL POPULATION, EMPLOYMENT, AND INCOME IN THE ROCKY MOUNTAIN WEST

There is controversy over the role that federal land plays in shaping rural counties in the Western United States. Some argue that the restrictive policies imposed on federal lands harm rural economies because the extractive industry is not allowed to operate at its potential. Others believe that those restrictions benefit rural economies because households and firms are attracted to beautiful areas with minimal industry. A lagged adjusted model is used to estimate the effects of Bureau of Land Management (BLM), United States Forest Service (USFS), and National Parks Service (NPS) lands on population, employment, and income. The study focuses on the Rocky Mountain West States during the 1990s. The equations are estimated simultaneously using 2SLS, 3SLS, and reduced form OLS procedures. The presence of USFS land was found to have a positive impact on employment, and the presence of NPS land positively impacted income. However, the magnitude of both effects was quite small. The argument that federal land harms rural economies was not verified, but federal land did not have a strong positive impact either

Shedding light on a living lab: the CLEF NEWSREEL open recommendation platform

In the CLEF NEWSREEL lab, participants are invited to evaluate news recommendation techniques in real-time by providing news recommendations to actual users that visit commercial news portals to satisfy their information needs. A central role within this lab is the communication between participants and the users. This is enabled by The Open Recommendation Platform (ORP), a web-based platform which distributes users' impressions of news articles to the participants and returns their recommendations to the readers. In this demo, we illustrate the platform and show how requests are handled to provide relevant news articles in real-time

Shipping Policies of Omnichannel Retailers: The Effect of Shipping Fees on Demands and Profitability

The omnichannel strategy that integrates online channels and traditional brick-and-mortar stores has been broadly utilised in retailing practices to deliver a seamless shopping experience. Early empirical studies have demonstrated its benefits: for physical stores, it brings footfall and increases the opportunity of cross-sells; for online channels, it allows customers to inspect the merchandise before purchase, thereby reducing the return rate. However, the relevant operating costs and the investment of channel integration can be substantial, yet the discussion on the pricing of omnichannel services is scarce. This thesis aims to provide insights to address the dilemmas omnichannel retailers face in the pre-purchase and post-purchase stages and identify the optimal pricing of omnichannel shipment. In the ex-ante stage, omnichannel retailers face a dilemma: charging omnichannel service at a low price could attract online traffic, yet financial loss may occur when stores are less profitable and integration costs outweigh cross-sales in-store. Hence, a stylised model is developed to study the shipping policy, especially the shipping fee for omnichannel service, and their impacts on customer demand and overall profitability. Three scenarios are considered: (1) shipment fee is consistent across channels; (2) omnichannel service is charged at a discounted rate or (3) free of charge. The results show that omnichannel positively convert online traffic into footfall instore but does not always grow total demands or boost overall profitability; charging a discounted rate could help retailers shift demands to a more profitable channel. This study identifies the optimal shipping policy that depends on the retailer’s operational efficiency and distribution costs. When the distribution cost is low, the retailer can offer free omnichannel shipment or charge a discounted rate if the cost is medium. Finally, the home delivery fee should be adjusted jointly with the omnichannel shipping fee. In the ex-post stage, customers need to decide whether and where they return the purchased product. Retailers face a trade-off: allowing cross-channel returns could reduce the shipment cost and potentially increase cross-sales in-store; however, handling returned products in-store means extra labour costs, such as inspecting, re-packing, re-storing. Moreover, stores potentially face financial loss if the returned product is re-sold in-store at a discounted price. Therefore, the features of omnichannel operations are incorporated in the post-purchase stage. A stylised model is built to characterise omnichannel operations and study how return policies impact customer channel choices and the retailer’s profitability. This study differentiates online channels with stores based on customer return behaviours. When customers purchase online, they need to bear the risk of receiving a product that does not match their expectations. Distinctively, store customers can inspect the product before purchase. Customers are assumed not to return a product if they purchase in-store. Hence, this model focuses on four return policies depending on return fees and whether cross-channel is available. The unit selling price is consistent across channels, and the retailer offers a full refund. In this model setting, purchase decision and return channel decisions are endogenous. The results suggest that cross-channel returns are not recommended if online returns are free, whereas retailers with a larger customer base and efficient in-store operations or wide store networks could benefit from omnichannel returns. Last, the optimal omnichannel return policy should be jointly considered with the existing online return policy. Overall, this thesis extends utility theory in understanding the customer’s cross-channel behaviours and use decision theory to analyse the omnichannel retailer’s service pricing in pre-and postpurchase stages. This analysis helps retailing practitioners to understand the scenario when the retailer should allow omnichannel implementations, such as buy online and collect or return instore, and the condition of optimal shipment pricing

Using Multiple Choice Questions to Assist Learning for Information Retrieval

A key issue in teaching and learning in information retrieval – particularly for library and information science students – is the gap in prior knowledge compared with the need for mathematics to conduct and evaluate searches. In this chapter, we examine the use of online Multiple Choice Questions to support these type of students, and narrow this gap between experience and knowledge. We provide some background in terms of related work and the use of MCQ’s for assessment. The key areas of search which can be supported by this form of assessment are defined, and these are used to outline a proposed strategy for defining a series of questions to support learning

Comparative evaluation of the performance of online databases in answering toxicology queries

An evaluation of toxicology information resources is reported, comparing commercial online databases and a specialised in-house database. A mixed qualitative/quantitative approach, using ten test queries and detailed failure analysis was used. The main conclusions are: the in-house database is superior to any ‘general’ database in recall and precision; commercial databases are a useful complement, usually providing unique material; a range of databases should be used for good recall; for the commercial databases, complex search strategies are necessary, using the specific access points of each database; retrieval failures are due primarily to coverage, secondly to poor indexing of specific toxic effect. Detailed discussion is given of indexing policies and search strategies

Managing the Knowledge Creation Process of Large-Scale Evaluation Campaigns

Περιέχει το πλήρες κείμενοThis paper discusses the evolution of large-scale evaluation campaigns and the corresponding evaluation infrastructures needed to carry them out. We present the next challenges for these initiatives and show how digital library systems can play a relevant role in supporting the research conducted in these fora by acting as virtual research environments

Local search: A guide for the information retrieval practitioner

There are a number of combinatorial optimisation problems in information retrieval in which the use of local search methods are worthwhile. The purpose of this paper is to show how local search can be used to solve some well known tasks in information retrieval (IR), how previous research in the field is piecemeal, bereft of a structure and methodologically flawed, and to suggest more rigorous ways of applying local search methods to solve IR problems. We provide a query based taxonomy for analysing the use of local search in IR tasks and an overview of issues such as fitness functions, statistical significance and test collections when conducting experiments on combinatorial optimisation problems. The paper gives a guide on the pitfalls and problems for IR practitioners who wish to use local search to solve their research issues, and gives practical advice on the use of such methods. The query based taxonomy is a novel structure which can be used by the IR practitioner in order to examine the use of local search in IR