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- Hägg, Sara, et al.
(författare)
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Molecular Phenotypes of Coronary Artery Disease : The Stockholm Atherosclerosis Gene Expression (STAGE) Study
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- BACKGROUNDBy offering a comprehensive view of the molecular underpinnings of pathology, high-dimensional data have the potential to revolutionize the diagnosis and management of complex disorders such as coronary artery disease (CAD). To identify molecular phenotypes of CAD, we performed multi organ gene expression profiling of subjects enrolled in the Stockholm Atherosclerosis Gene Expression (STAGE) study.METHODSAtherosclerotic and unaffected arterial wall, liver, skeletal muscle, and mediastinal fat biopsies were obtained during coronary artery bypass grafting from 114 well-characterized CAD patients. RNA samples were isolated, and 278 transcription profiles were obtained using Affymetrix HG-U133_Plus_2 GeneChips.RESULTSThe most prominent molecular phenotype of the CAD patients was represented by 733 genes in mediastinal fat, which were involved in extracellular matrix organization, response to stress and regulation of programmed cell death. Other aspects of this phenotype were shared with liver (e.g., oxidoreductase activity), skeletal muscle (insulin-like growth factor binding), and atherosclerotic arterial wall (cell motility and adhesion, fatty acid metabolism). In addition, the activity of 400 genes exclusively in mediastinal fat was associated with the extent of coronary stenosis and atherosclerosis. Immune-cell activation in mediastinal fat defined CAD patients with poor blood glucose control and prolonged hospitalization.CONCLUSIONSThe molecular phenotype of mediastinal fat appears to be central in CAD and should be useful for early identification of CAD risk.
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- Byberg, Liisa, 1972-
(författare)
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Plasminogen Activator Inhibitor-1 and the Insulin Resistance Syndrome
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis, different aspects of the insulin resistance syndrome in relation to plasminogen activator inhibitor-1 (PAI-1) activity are investigated in a longitudinal population-based study. Participants were men investigated at ages 50 and 70 with follow-up data on mortality.High PAI-1 activity was associated with low insulin sensitivity, high concentrations of serum triglycerides, high body mass index and high waist/hip ratio, independently of each other and of potential confounders. Low birth weight predicted high blood pressure, insulin resistance, truncal obesity and high PAI-1 activity but not the abdominal obesity or dyslipidaemia present in the insulin resistance syndrome. Increased physical activity level between 50 and 70 years of age, in the absence of active intervention, was associated with improved glucose, insulin, proinsulin and lipoprotein metabolism. Insulin and proinsulin seemed to be important factors that mediate much of the association between a sedentary lifestyle and increased risk of cardiovascular disease. The reported dietary intake of both mono- and polyunsaturated fatty acids was positively associated with PAI-1 activity, whereas saturated fatty acid intake displayed no association. The associations present between PAI-1 activity and the fatty acid proportions in serum cholesterol esters were partly influenced by factors related with the insulin resistance syndrome.This thesis provides further knowledge to the epidemiological view of the interrelations of the insulin resistance syndrome, PAI-1, birth weight, and lifestyle factors as physical activity and dietary habits. PAI-1 is a part of the insulin resistance syndrome and is associated both with modifiable and non-modifiable factors related with this syndrome.
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- Frånberg, Mattias, 1985-
(författare)
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Statistical methods for detecting gene-gene and gene-environment interactions in genome-wide association studies
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Despite considerable effort to elucidate the genetic architecture of multi-factorial traits and diseases, there remains a gap between the estimated heritability (e.g., from twin studies) and the heritability explained by discovered genetic variants. The existence of interactions between different genes, and between genes and the environment, has frequently been hypothesized as a likely cause of this discrepancy. However, the statistical inference of interactions is plagued by limited sample sizes, high computational requirements, and incomplete knowledge of how the measurement scale and parameterization affect the analysis.This thesis addresses the major statistical, computational, and modeling issues that hamper large-scale interaction studies today. Furthermore, it investigates whether gene-gene and gene-environment interactions are significantly involved in the development of diseases linked to atherosclerosis. Firstly, I develop two statistical methods that can be used to study of gene-gene interactions: the first is tailored for limited sample size situations, and the second enables multiple analyses to be combined into large meta-analyses. I perform comprehensive simulation studies to determine that these methods have higher or equal statistical power than contemporary methods, scale-invariance is required to guard against false positives, and that saturated parameterizations perform well in terms of statistical power. In two studies, I apply the two proposed methods to case/control data from myocardial infarction and associated phenotypes. In both studies, we identify putative interactions for myocardial infarction but are unable to replicate the interactions in a separate cohort. In the second study, however, we identify and replicate a putative interaction involved in Lp(a) plasma levels between two variants rs3103353 and rs9458157. Secondly, I develop a multivariate statistical method that simultaneously estimates the effects of genetic variants, environmental variables, and their interactions. I show by extensive simulations that this method achieves statistical power close to the optimal oracle method. We use this method to study the involvement of gene-environment interactions in intima-media thickness, a phenotype relevant for coronary artery disease. We identify a putative interaction between a genetic variant in the KCTD8 gene and alcohol use, thus suggesting an influence on intima-media thickness. The methods developed to support the analyses in this thesis as well as a selection of other prominent methods in the field is implemented in a software package called besiq.In conclusion, this thesis presents statistical methods, and the associated software, that allows large-scale studies of gene-gene and gene-environment interactions to be effortlessly undertaken.
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- Skogsberg, Josefin, et al.
(författare)
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Whole-genome expression profiling of human plaques to identify genes relevant for atherosclerosis : the Stockholm Atherosclerosis Gene Expression Study, Stockholm Söder Hospital, Sweden (SöS-STAGE)
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- ObjectiveTo reveal relevant genes for atherosclerosis by whole-genome expression analyses of plaques from patients undergoing carotid endorectomy.Methods and ResultsWhole-genome expression measurements (WGEM) using Affymetrix HG-U133_Plus_2 chip of carotid plaques in patients undergoing carotid endorectomy at Stockholm Söder Hospital, Sweden. Patients were screened for conventional risk factors at a three-month follow-up visit and atherosclerosis burden in the common carotid artery (CCA) was measured by intima-media thickness (IMT). An unsupervised coupled two-way clustering approach identified genderspecific genes and 55 genes associated to degree of IMT in these patients.ConclusionsCoupled two-way clustering of carotid lesion expression profiles from a well-characterized clinical cohort is useful for identification of novel genes that may be relevant for atheroscleroris.
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