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90 result(s) for "Green, Fiona R"
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Fibrinogen and clot-related phenotypes determined by fibrinogen polymorphisms: Independent and IL-6-interactive associations
Interleukin-6 (IL-6) induces the expression of fibrinogen, and polymorphic variation within the fibrinogen genes is believed to alter the magnitude of this expression. The identification of the functional relevance of individual fibrinogen single nucleotide polymorphisms (SNPs) has been hindered by the high linkage disequilibrium (LD) reported in the European fibrinogen gene locus. This study investigated two novel and 12 known fibrinogen SNPs of potential functional relevance, in 2010 Tswana individuals known to have low LD. We aimed to identify functional polymorphisms that contribute to clot-related phenotypes and total and γ' fibrinogen concentrations independently and through their interaction with IL-6, by taking advantage of the high fibrinogen and IL-6 concentrations and the low LD reported in black South Africans. Fibrinogen was significantly associated with IL-6, thereby mediating associations of IL-6 with clot formation and structure, although attenuating the association of IL-6 with clot lysis time. None of the common European fibrinogen haplotypes was present in this study population. Putative functional fibrinogen SNPs FGB-rs7439150, rs1800789 (-1420G/A) and rs1800787 (-148C/T) were significantly associated with fibrinogen concentration and altered clot properties, with several associations significantly influenced by IL-6 concentrations. The impact of harbouring several minor fibrinogen SNP alleles on the association of IL-6 and fibrinogen concentration was cumulative, with possession of each additional minor allele showing a stronger relationship of IL-6 with fibrinogen. This was also reflected in differences in clot properties, suggesting potential clinical relevance. Therefore, when investigating the effect of fibrinogen genetics on fibrinogen concentrations and CVD outcome, the possible interactions with modulating factors and the fact that SNP effects seem to be additive should be taken into account.
Boosting and lassoing new prostate cancer SNP risk factors and their connection to selenium
We begin by arguing that the often used algorithm for the discovery and use of disease risk factors, stepwise logistic regression, is unstable. We then argue that there are other algorithms available that are much more stable and reliable (e.g. the lasso and gradient boosting). We then propose a protocol for the discovery and use of risk factors using lasso or boosting variable selection. We then illustrate the use of the protocol with a set of prostate cancer data and show that it recovers known risk factors. Finally, we use the protocol to identify new and important SNP based risk factors for prostate cancer and further seek evidence for or against the hypothesis of an anticancer function for Selenium in prostate cancer. We find that the anticancer effect may depend on the SNP-SNP interaction and, in particular, which alleles are present.
Methylation vs. Protein Inflammatory Biomarkers and Their Associations With Cardiovascular Function
DNA methylation data can be used to estimate proportions of leukocyte subsets retrospectively, when directly measured cell counts are unavailable. The methylation-derived neutrophil-to-lymphocyte and lymphocyte-to-monocyte ratios (mdNLRs and mdLMRs) have proven to be particularly useful as indicators of systemic inflammation. As with directly measured NLRs and LMRs, these methylation-derived ratios have been used as prognostic markers for cancer, although little is known about them in relation to other disorders with inflammatory components, such as cardiovascular disease (CVD). Recently, methylation of five genomic cytosine-phosphate-guanine sites (CpGs) was suggested as proxies for mdNLRs, potentially providing a cost-effective alternative when whole-genome methylation data are not available. This study compares seven methylation-derived inflammatory markers (mdNLR, mdLMR, and individual CpG sites) with five conventionally used protein-based inflammatory markers (C-reactive protein, interleukins 6 and 10, tumor-necrosis factor alpha, and interferon-gamma) and a protein-based inflammation score, in their associations with cardiovascular function (CVF) and risk. We found that markers of CVF were more strongly associated with methylation-derived than protein-based markers. In addition, the protein-based and methylation-derived inflammatory markers complemented rather than proxied one another in their contribution to the variance in CVF. There were no strong correlations between the methylation and protein markers either. Therefore, the methylation markers could offer unique information on the inflammatory process and are not just surrogate markers for inflammatory proteins. Although the five CpGs mirrored the mdNLR well in their capacity as proxies, they contributed to CVF above and beyond the mdNLR, suggesting possible added functional relevance. We conclude that methylation-derived indicators of inflammation enable individuals with increased CVD risk to be identified without measurement of protein-based inflammatory markers. In addition, the five CpGs investigated here could be useful surrogates for the NLR when the cost of array data cannot be met. Used in tandem, methylation-derived and protein-based inflammatory markers explain more variance than protein-based inflammatory markers alone.
Genetic Variants Associated with Lp(a) Lipoprotein Level and Coronary Disease
Using a novel gene chip, investigators identified single-nucleotide polymorphisms (SNPs) from three chromosomal regions, including the LPA locus, that were associated with the risk of coronary disease. Two SNPs in LPA were strongly associated with both the level of Lp(a) lipoprotein and the risk of coronary disease. After adjustment for the Lp(a) lipoprotein level, the association with the risk of coronary disease was abolished. These findings support a causal role of an increased Lp(a) lipoprotein level in the risk of coronary disease. Two SNPs in the LPA locus were strongly associated with both the level of Lp(a) lipoprotein and the risk of coronary disease. These findings support a causal role of an increased Lp(a) lipoprotein level in the risk of coronary disease. Genomewide association studies have identified several novel susceptibility loci for coronary artery disease, 1 – 4 but it is likely that only common variants can be detected in this way. 5 , 6 Moreover, loci that are identified with the use of genomewide association studies explain only a small amount of the expected contribution to the risk of coronary disease. The use of arrays of high-density single-nucleotide polymorphisms (SNPs) in candidate genes for cardiovascular disease may help elucidate the genetic contribution to the risk of coronary disease. A recent genomewide association study showed that a cluster of genes — solute carrier family 22 member . . .
Genome-Wide Mapping of Susceptibility to Coronary Artery Disease Identifies a Novel Replicated Locus on Chromosome 17
Coronary artery disease (CAD) is a leading cause of death world-wide, and most cases have a complex, multifactorial aetiology that includes a substantial heritable component. Identification of new genes involved in CAD may inform pathogenesis and provide new therapeutic targets. The PROCARDIS study recruited 2,658 affected sibling pairs (ASPs) with onset of CAD before age 66 y from four European countries to map susceptibility loci for CAD. ASPs were defined as having CAD phenotype if both had CAD, or myocardial infarction (MI) phenotype if both had a MI. In a first study, involving a genome-wide linkage screen, tentative loci were mapped to Chromosomes 3 and 11 with the CAD phenotype (1,464 ASPs), and to Chromosome 17 with the MI phenotype (739 ASPs). In a second study, these loci were examined with a dense panel of grid-tightening markers in an independent set of families (1,194 CAD and 344 MI ASPs). This replication study showed a significant result on Chromosome 17 (MI phenotype; p = 0.009 after adjustment for three independent replication tests). An exclusion analysis suggests that further genes of effect size lambda(sib) > 1.24 are unlikely to exist in these populations of European ancestry. To our knowledge, this is the first genome-wide linkage analysis to map, and replicate, a CAD locus. The region on Chromosome 17 provides a compelling target within which to identify novel genes underlying CAD. Understanding the genetic aetiology of CAD may lead to novel preventative and/or therapeutic strategies.
Genome-wide mapping of susceptibility to coronary artery disease identifies a novel replicated locus on chromosome 17
Coronary artery disease (CAD) is a leading cause of death world-wide, and most cases have a complex, multifactorial aetiology that includes a substantial heritable component. Identification of new genes involved in CAD may inform pathogenesis and provide new therapeutic targets. The PROCARDIS study recruited 2,658 affected sibling pairs (ASPs) with onset of CAD before age 66 y from four European countries to map susceptibility loci for CAD. ASPs were defined as having CAD phenotype if both had CAD, or myocardial infarction (MI) phenotype if both had a MI. In a first study, involving a genome-wide linkage screen, tentative loci were mapped to Chromosomes 3 and 11 with the CAD phenotype (1,464 ASPs), and to Chromosome 17 with the MI phenotype (739 ASPs). In a second study, these loci were examined with a dense panel of grid-tightening markers in an independent set of families (1,194 CAD and 344 MI ASPs). This replication study showed a significant result on Chromosome 17 (MI phenotype; p = 0.009 after adjustment for three independent replication tests). An exclusion analysis suggests that further genes of effect size lambda(sib) > 1.24 are unlikely to exist in these populations of European ancestry. To our knowledge, this is the first genome-wide linkage analysis to map, and replicate, a CAD locus. The region on Chromosome 17 provides a compelling target within which to identify novel genes underlying CAD. Understanding the genetic aetiology of CAD may lead to novel preventative and/or therapeutic strategies.
Controlling the fluorescence and room-temperature phosphorescence behaviour of carbon nanodots with inorganic crystalline nanocomposites
There is a significant drive to identify alternative materials that exhibit room temperature phosphorescence for technologies including bio-imaging, photodynamic therapy and organic light-emitting diodes. Ideally, these materials should be non-toxic and cheap, and it will be possible to control their photoluminescent properties. This was achieved here by embedding carbon nanodots within crystalline particles of alkaline earth carbonates, sulphates and oxalates. The resultant nanocomposites are luminescent and exhibit a bright, sub-second lifetime afterglow. Importantly, the excited state lifetimes, and steady-state and afterglow colours can all be systematically controlled by varying the cations and anions in the host inorganic phase, due to the influence of the cation size and material density on emissive and non-emissive electronic transitions. This simple strategy provides a flexible route for generating materials with specific, phosphorescent properties and is an exciting alternative to approaches relying on the synthesis of custom-made luminescent organic molecules. Materials exhibiting room temperature phosphorescence (RTP) with short afterglow are desirable for bio-medical applications. Here the authors synthesise a library of compounds with tunable RTP properties, embedding carbon nanodots in non-toxic alkaline-earth carbonate, sulphate and oxalate hosts.
The Ancient Drug Salicylate Directly Activates AMP-Activated Protein Kinase
Salicylate, a plant product, has been in medicinal use since ancient times. More recently, it has been replaced by synthetic derivatives such as aspirin and salsalate, both of which are rapidly broken down to salicylate in vivo. At concentrations reached in plasma after administration of salsalate or of aspirin at high doses, salicylate activates adenosine monophosphate-activated protein kinase (AMPK), a central regulator of cell growth and metabolism. Salicylate binds at the same site as the synthetic activator A-769662 to cause allosteric activation and inhibition of dephosphorylation of the activating phosphorylation site, threonine-172. In AMPK knockout mice, effects of salicylate to increase fat utilization and to lower plasma fatty acids in vivo were lost. Our results suggest that AMPK activation could explain some beneficial effects of salsalate and aspirin in humans.
Agreement between two large pan-cancer CRISPR-Cas9 gene dependency data sets
Genome-scale CRISPR-Cas9 viability screens performed in cancer cell lines provide a systematic approach to identify cancer dependencies and new therapeutic targets. As multiple large-scale screens become available, a formal assessment of the reproducibility of these experiments becomes necessary. We analyze data from recently published pan-cancer CRISPR-Cas9 screens performed at the Broad and Sanger Institutes. Despite significant differences in experimental protocols and reagents, we find that the screen results are highly concordant across multiple metrics with both common and specific dependencies jointly identified across the two studies. Furthermore, robust biomarkers of gene dependency found in one data set are recovered in the other. Through further analysis and replication experiments at each institute, we show that batch effects are driven principally by two key experimental parameters: the reagent library and the assay length. These results indicate that the Broad and Sanger CRISPR-Cas9 viability screens yield robust and reproducible findings. Integrating independent large-scale pharmacogenomic screens can enable unprecedented characterization of genetic vulnerabilities in cancers. Here, the authors show that the two largest independent CRISPR-Cas9 gene-dependency screens are concordant, paving the way for joint analysis of the data sets.
Research publications of Australia’s natural history museums, 1981–2020: Enduring relevance in a changing world
As a case study of the responses of natural history museums to changing scientific and funding environments, we analysed research publications of Australia’s Natural History Museums (ANHMs) 1981–2020. Using Scopus, 9,923 relevant documents 1981–2020 were identified, mainly research papers but with a growing proportion of reviews. The number of documents published increased over tenfold from 39 (1981) to 553 (2020), likely driven by collaborations (rising from 28.5% of documents 1981–1985 to 87.2% of documents 2016–2020), contributions from retired staff, and volunteer support. The mean length of documents (pages) ranged from a low of 15.3 in 2001–2005 to a high of 17.4 in 1991–1995, but this statistically significant result was trivial in practical terms. The sources (i.e., journals, book titles, conference proceedings) in which ANHM authors published changed over time, with growing proportions of publications in journals covering molecular ecology/phylogenetics and biological conservation. We identified the major areas of study canvassed within the corpus of publications by developing structural topic models based on patterns of word use in document titles, abstracts and keyword lists. The topics discovered included study subjects traditional for natural history museums (new taxa, phylogeny, systematics, animal morphology, palaeontology, minerals), new directions (molecular genetics, ecology, biological conservation) and marine biology (probably reflecting Australia’s large coastline). Most citations came from Australia, USA and UK, although in 2016–2020 only 27.9% of citing documents included an Australian author. Growth in numbers of documents and collaborations, as well as use of documents internationally over a period of great change in scientific and funding environments, indicate an enduring legacy of ANHM research, grounded on the intrinsic value of the collections.