534 research outputs found

    Quantitative imaging of coronary blood flow

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    Positron emission tomography (PET) is a nuclear medicine imaging modality based on the administration of a positron-emitting radiotracer, the imaging of the distribution and kinetics of the tracer, and the interpretation of the physiological events and their meaning with respect to health and disease. PET imaging was introduced in the 1970s and numerous advances in radiotracers and detection systems have enabled this modality to address a wide variety of clinical tasks, such as the detection of cancer, staging of Alzheimer's disease, and assessment of coronary artery disease (CAD). This review provides a description of the logic and the logistics of the processes required for PET imaging and a discussion of its use in guiding the treatment of CAD. Finally, we outline prospects and limitations of nanoparticles as agents for PET imaging

    SerpinB2 regulates stromal remodelling and local invasion in pancreatic cancer

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    Pancreatic cancer has a devastating prognosis, with an overall 5-year survival rate of ~8%, restricted treatment options and characteristic molecular heterogeneity. SerpinB2 expression, particularly in the stromal compartment, is associated with reduced metastasis and prolonged survival in pancreatic ductal adenocarcinoma (PDAC) and our genomic analysis revealed that SERPINB2 is frequently deleted in PDAC. We show that SerpinB2 is required by stromal cells for normal collagen remodelling in vitro, regulating fibroblast interaction and engagement with collagen in the contracting matrix. In a pancreatic cancer allograft model, co-injection of PDAC cancer cells and SerpinB2(-/-) mouse embryonic fibroblasts (MEFs) resulted in increased tumour growth, aberrant remodelling of the extracellular matrix (ECM) and increased local invasion from the primary tumour. These tumours also displayed elevated proteolytic activity of the primary biochemical target of SerpinB2-urokinase plasminogen activator (uPA). In a large cohort of patients with resected PDAC, we show that increasing uPA mRNA expression was significantly associated with poorer survival following pancreatectomy. This study establishes a novel role for SerpinB2 in the stromal compartment in PDAC invasion through regulation of stromal remodelling and highlights the SerpinB2/uPA axis for further investigation as a potential therapeutic target in pancreatic cancer

    Bone mineral density by digital X-ray radiogrammetry is strongly decreased and associated with joint destruction in long-standing Rheumatoid Arthritis: a cross-sectional study

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    <p>Abstract</p> <p>Background</p> <p>The aims were to explore bone mineral density (BMD) by digital X-ray radiogrammetry (DXR) in postmenopausal women with long-lasting rheumatoid arthritis (RA) in relation to dual x-ray absorptiometry (DXA)-BMD, joint destruction by conventional radiographs and disease related variables in a cross-sectional study.</p> <p>Methods</p> <p>Seventy-five postmenopausal women with RA were examined by DXA measuring DXA-BMD of the forearm, total hip and lumbar spine, by scoring joint destruction on plain radiographs by the method of Larsen and by DXR-BMD in metacarpals two to four. The DXR-BMD results of the RA women were compared with an age and sex-matched reference database. A function of DXR-BMD in relation to age and disease duration was created. Associations were investigated by bivariate and multiple linear regression analyses.</p> <p>Results</p> <p>DXR-BMD was strongly decreased in RA patients compared to the reference database (p < 0.001). Calculations showed that DXR-BMD was not markedly influenced the first years after diagnosis of RA, but between approximately 5-10 years of disease there was a steep decline in DXR-BMD which subsequently levelled off. In multiple regression analyses disease duration, CRP and DXR-BMD were independent variables associated with Larsen score (R<sup>2</sup>= 0.64). Larsen score and BMD forearm were independent determinants of DXR-BMD (R<sup>2 </sup>= 0.79).</p> <p>Conclusions</p> <p>DXR-BMD was strongly reduced and associated with both Larsen score and DXA-BMD forearm in these postmenopausal women with RA implying that DXR-BMD is a technique that reflects both the erosive process and bone loss adjacent to affected joints.</p

    Analysis and comparison of very large metagenomes with fast clustering and functional annotation

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    <p>Abstract</p> <p>Background</p> <p>The remarkable advance of metagenomics presents significant new challenges in data analysis. Metagenomic datasets (metagenomes) are large collections of sequencing reads from anonymous species within particular environments. Computational analyses for very large metagenomes are extremely time-consuming, and there are often many novel sequences in these metagenomes that are not fully utilized. The number of available metagenomes is rapidly increasing, so fast and efficient metagenome comparison methods are in great demand.</p> <p>Results</p> <p>The new metagenomic data analysis method Rapid Analysis of Multiple Metagenomes with a Clustering and Annotation Pipeline (<b>RAMMCAP</b>) was developed using an ultra-fast sequence clustering algorithm, fast protein family annotation tools, and a novel statistical metagenome comparison method that employs a unique graphic interface. RAMMCAP processes extremely large datasets with only moderate computational effort. It identifies raw read clusters and protein clusters that may include novel gene families, and compares metagenomes using clusters or functional annotations calculated by RAMMCAP. In this study, RAMMCAP was applied to the two largest available metagenomic collections, the "Global Ocean Sampling" and the "Metagenomic Profiling of Nine Biomes".</p> <p>Conclusion</p> <p>RAMMCAP is a very fast method that can cluster and annotate one million metagenomic reads in only hundreds of CPU hours. It is available from <url>http://tools.camera.calit2.net/camera/rammcap/</url>.</p

    Exploring hypotheses of the actions of TGF-beta 1 in epidermal wound healing using a 3D computational multiscale model of the human epidermis

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    In vivo and in vitro studies give a paradoxical picture of the actions of the key regulatory factor TGF-beta 1 in epidermal wound healing with it stimulating migration of keratinocytes but also inhibiting their proliferation. To try to reconcile these into an easily visualized 3D model of wound healing amenable for experimentation by cell biologists, a multiscale model of the formation of a 3D skin epithelium was established with TGF-beta 1 literature-derived rule sets and equations embedded within it. At the cellular level, an agent-based bottom-up model that focuses on individual interacting units ( keratinocytes) was used. This was based on literature-derived rules governing keratinocyte behavior and keratinocyte/ECM interactions. The selection of these rule sets is described in detail in this paper. The agent-based model was then linked with a subcellular model of TGF-beta 1 production and its action on keratinocytes simulated with a complex pathway simulator. This multiscale model can be run at a cellular level only or at a combined cellular/subcellular level. It was then initially challenged ( by wounding) to investigate the behavior of keratinocytes in wound healing at the cellular level. To investigate the possible actions of TGF-beta 1, several hypotheses were then explored by deliberately manipulating some of these rule sets at subcellular levels. This exercise readily eliminated some hypotheses and identified a sequence of spatial-temporal actions of TGF-beta 1 for normal successful wound healing in an easy-to-follow 3D model. We suggest this multiscale model offers a valuable, easy-to-visualize aid to our understanding of the actions of this key regulator in wound healing, and provides a model that can now be used to explore pathologies of wound healing

    Early changes in bone mineral density measured by digital X-ray radiogrammetry predict up to 20 years radiological outcome in rheumatoid arthritis

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    ABSTRACT: INTRODUCTION: Change in bone mineral density (BMD) in the hand, as evaluated by digital X-ray radiogrammetry (DXR) of the II-IV metacarpal bones, has been suggested to predict future joint damage in rheumatoid arthritis (RA). This study's objective was to investigate if DXR-BMD loss early in the disease predicts development of joint damage in RA patients followed for up to 20 years. METHODS: 183 patients (115 women and 68 men) with early RA (mean disease duration 11 months) included from 1985 to 1989 were followed prospectively (the Lund early RA cohort). Clinical and functional measures were assessed yearly. Joint damage was evaluated according to the Larsen score on radiographs of hands and feet taken in years 0 to 5, 10, 15 and 20. These radiographs were digitized and BMD of the II-IV metacarpal bones was evaluated by DXR (Sectra, Linkoping. Sweden). Early DXR-BMD change rate (bone loss) per year calculated from the first 2 radiographs taken on average 9 months apart (SD 4.8) were available for 135 patients. Mean values of right and left hand were used. RESULTS: Mean early DXR-BMD loss during the first year calculated was -0.023 g/cm2 (SD 0.025). Patients with marked bone loss, i.e. early DXR-BMD loss above the median for the group, had significantly worse progression of joint damage at all examinations during the 20-year period. CONCLUSIONS: Early DXR-BMD progression rate predicted development of joint damage evaluated according to Larsen at year one and further onwards up to 20 years in this cohort of early RA patients

    Regulation of early signaling and gene expression in the α-particle and bystander response of IMR-90 human fibroblasts

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    <p>Abstract</p> <p>Background</p> <p>The existence of a radiation bystander effect, in which non-irradiated cells respond to signals from irradiated cells, is well established. To understand early signaling and gene regulation in bystander cells, we used a bio-informatics approach, measuring global gene expression at 30 minutes and signaling pathways between 30 minutes and 4 hours after exposure to α-particles in IMR-90 fibroblasts.</p> <p>Methods</p> <p>We used whole human genome microarrays and real time quantitative PCR to measure and validate gene expression. Microarray analysis was done using BRB-Array Tools; pathway and ontology analyses were done using Ingenuity Pathway Analysis and PANTHER, respectively. We studied signaling in irradiated and bystander cells using immunoblotting and semi-quantitative image analysis.</p> <p>Results</p> <p>Gene ontology suggested signal transduction and transcriptional regulation responding 30 minutes after treatment affected cell structure, motility and adhesion, and interleukin synthesis. We measured time-dependent expression of genes controlled by the NF-ÎșB pathway; matrix metalloproteinases 1 and 3; <it/>chemokine ligands 2, 3 and 5 and <it/>interleukins 1ÎČ, 6 and 33. There was an increased response of this set of genes 30 minutes after treatment and another wave of induction at 4 hours. We investigated AKT-GSK3ÎČ signaling and found both AKT and GSK3ÎČ are hyper-phosphorylated 30 minutes after irradiation and this effect is maintained through 4 hours. In bystander cells, a similar response was seen with a delay of 30 minutes. We proposed a network model where the observed decrease in phosphorylation of ÎČ-catenin protein after GSK3ÎČ dependent inactivation can trigger target gene expression at later times after radiation exposure</p> <p>Conclusions</p> <p>These results are the first to show that the radiation induced bystander signal induces a widespread gene expression response at 30 minutes after treatment and these changes are accompanied by modification of signaling proteins in the PI3K-AKT-GSK3ÎČ pathway.</p

    Framing REDD+ in the Brazilian national media: how discourses evolved amid global negotiation uncertainties

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    Reducing emissions from deforestation and degradation (REDD+) in tropical countries is an important and contested element of the post-Kyoto climate regime. For policy options which generate controversy between diverse actor groups, such as REDD+, mass media plays an important role in defining and supporting policy possibilities. Analysis of the way in which national media frames issues of climate change and deforestation can offer insights into the nature of the contested domains of the REDD+ policy process. Here, we examine the Brazilian national media discourses surrounding REDD+ because it contributes to setting the tone of policy debates at the federal level. Specifically, we ask the following: (i) How was REDD+ portrayed in the Brazilian national print media and whose opinions and perceptions were represented? and (ii) How have media frames on REDD+ in the national print media changed over time? Our results contribute with new knowledge for understanding the observed progress of REDD+ in Brazil. We identify two main themes that dominate the focus in the national media coverage of REDD+, specifically “politics and policymaking” (representing half the coverage) and “economics and market” (with over a third). Results show that discussions around carbon markets were amongst the most contested and that optimism in relation to REDD+ effectiveness declined over time. The analysis suggests that positions adopted on the national REDD+ strategy were shaped by state and federal collision of interests. We demonstrate an evolution of national concerns from an initial focus on efficiency (e.g. finance and carbon markets) to a recentred focus on equity issues (e.g. implementation of safeguards). We conclude with some thoughts on the implications of these features for REDD+ interventions and implementation in Brazil
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