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Repository of the University of Hasselt containing publications in the fields of statistics, computer science, information strategies and material from the Institute for behavioural sciences.

Applied Mathematics

Mostrando recursos 1 - 20 de 540

  1. A generic approach for "shotgun" analysis of the soluble proteome of plant cell suspension cultures

    De Vijlder, Thomas; VALKENBORG, Dirk; Dewaele, Debbie; Remmerie, Noor; Laukens, Kris; Witters, Erwin
    Cell suspension cultures from different plant species act as important model systems for studying cellular processes in plant biology and are often used as "green factories" for the production of valuable secondary metabolites and recombinant proteins. While mass spectrometry based proteome analysis techniques are ideally suited to study plant cell metabolism and other fundamental cellular processes from a birds eye perspective, they remain underused in plant studies. We describe a comprehensive sample preparation and multidimensional 'shotgun' proteomics strategy that can be generically applied to plant cell suspension cultures. This strategy was optimized and tested on an Arabidopsis thaliana ecotype Landsberg...

  2. Linear mixed-effects models for central statistical monitoring of multicenter clinical trials

    Desmet, L.; Venet, D.; Doffagne, E.; Timmermans, C.; BURZYKOWSKI, Tomasz; LEGRAND, Catherine; BUYSE, Marc
    Multicenter studies are widely used to meet accrual targets in clinical trials. Clinical data monitoring is required to ensure the quality and validity of the data gathered across centers. One approach to this end is central statistical monitoring, which aims at detecting atypical patterns in the data by means of statistical methods. In this context, we consider the simple case of a continuous variable, and we propose a detection procedure based on a linear mixed-effects model to detect location differences between each center and all other centers. We describe the performance of the procedure as a function of contamination rate...

  3. Exploring the association between resistance and outpatient antibiotic use expressed as DDDs or packages

    Objectives: The objective of this study was to explore the association between resistance and outpatient antibiotic use, expressed as either DDDs per 1000 inhabitants per day (DID) or packages per 1000 inhabitants per day (PID). Methods: IMS Health data on outpatient penicillin and cephalosporin (β-lactam) and tetracycline, macrolide, lincosamide and streptogramin (TMLS) use, aggregated at the level of the active substance (WHO version 2011) expressed as DID and PID (2000–07) were linked to European Antimicrobial Resistance Surveillance System (EARSS) data on proportions of penicillin-non-susceptible Streptococcus pneumoniae (PNSP) and erythromycin-non-susceptible S. pneumoniae (ENSP) (2000–09). Combined data for 27 European countries were analysed...

  4. Compensating for memory losses throughout aging: Validation and normalization of the memory compensation questionnaire (MCQ) for non-clinical French populations

    Martin, Sophie; Mazzocco, Cl??mence; Maury, Pascale; Grosselin, Anne; VAN DER ELST, Wim; Dixon, Roger A.; Brouillet, Denis
    Aim: The MCQ is a seven-factor scale that measures individual differences in the tendency to select particular strategies and to overcome perceived or real memory losses. Our aim was to establish a French version of the MCQ and to evaluate its psychometric properties in a lifespan perspective. We first tested the underlying factor structure of the MCQ in a large sample of 749 adults from aged from 18 to 92 years. Results: The results showed that the factor structure of the French version corresponded well with the one obtained in English-, Dutch- and Spanish-speaking samples, supporting the cross-national robustness of...

  5. Data Sharing, Year 1 - Access to Data from Industry-Sponsored Clinical Trials

    Strom, Brian L.; BUYSE, Marc; Hughes, John; Knoppers, Bartha M.

  6. A hidden Markov-model for gene mapping based on whole-genome next generation sequencing data

    Claesen, Jürgen; Burzykowski, Tomasz
    The analysis of polygenic, phenotypic characteristics such as quantitative traits or inheritable diseases requires reliable scoring of many genetic markers covering the entire genome. The advent of high-throughput sequencing technologies provides a new way to evaluate large numbers of single nucleotide polymorphisms as genetic markers. Combining the technologies with pooling of segregants, as performed in bulk segregant analysis, should, in principle, allow the simultaneous mapping of multiple genetic loci present throughout the genome. We propose a hidden Markov-model to analyze the marker data obtained by the bulk segregant next generation sequencing. The model includes several states, each associated with a...

  7. Exercise training improves insulin release during glucose tolerance testing in stable chronic heart failure patients.

    STEVENS, An; HANSEN, Dominique; HERBOTS, Lieven; WENS, Inez; CREEMERS, An; DENDALE, Paul; EIJNDE, Bert O.
    PURPOSE: Chronic heart failure (CHF) patients often present with (pre)diabetes, which negatively influences prognosis. Unlike the proven effect of exercise on glucose regulation in the general population, its effect in CHF is unclear. Therefore, this study aimed at investigating the effect of exercise training on glucose regulation in stable CHF patients. METHODS: Twenty-two CHF patients were randomized into training (EX,n = 15) and control (CON, n = 7) groups. Before and after a 12-week training intervention involving endurance and resistance training, glucose tolerance (2-hour oral glucose tolerance test), exercise tolerance (cardiopulmonary exercise test), muscle strength (isokinetic dynamometer), heart function (echocardiography), glycated...

  8. Environmental pollutants and DNA damage in adolescents of the 2nd Flemish Environment and Health Study (FLEHSII)

    Franken, Carmen; Govarts, Eva; Lambrechts, Nathalie; Koppen, Gudrun; Den Hond, Elly; Colles, Ann; BRUCKERS, Liesbeth; Loots, Ilse; Morrens, Bert; Nelen, Vera; Sioen, Isabelle; Croes, Kim; Baeyens, Willy; Van Larebeke, Nicolas; Schoeters, Greet

  9. Is there a correlation between maternal venous hemodynamic dysfunction and proteinuria of preeclampsia?

    Mesens, Tinne; TOMSIN, Kathleen; STAELENS, Anneleen; OBEN, Jolien; MOLENBERGHS, Geert; GYSELAERS, Wilfried
    Objectives: To evaluate in early and late preeclampsia a correlation of maternal venous Doppler flow characteristics with biochemical parameters in maternal serum and urine, or with gestational outcome. Study design: In this observational cross-sectional study, renal interlobar vein impedance index (RIVI) was measured according to a standardised protocol for combined electrocardiogram-Doppler ultrasonography in 86 women with uncomplicated pregnancy, 78 women with late onset preeclampsia (>= 34 w) and 67 with early onset preeclampsia (<34 w). For each group, maternal age, pre-gestational BMI and parity were recorded together with birth weight and percentile. For both early onset and late onset preeclampsia,...

  10. Clinical validation of CardiMoni, a smartphone application that detects atrial fibrillation

    DRIJKONINGEN, Lenn; Van der Auwera, J.; SMEETS, Christophe; STORMS, Valerie; NUYENS, Dirk; VANDERVOORT, Pieter; GRIETEN, Lars; Lenaerts, F.

  11. Cost-effectiveness of seasonal influenza vaccination in pregnant women, health care workers and persons with underlying illnesses in Belgium

    Blommaert, Adriaan; Bilcke, Joke; VANDENDIJCK, Yannick; Hanquet, Germaine; HENS, Niel; Beutels, Philippe
    Risk groups with increased vulnerability for influenza complications such as pregnant women, persons with underlying illnesses as well as persons who come into contact with them, such as health care workers, are currently given priority (along with other classic target groups) to receive seasonal influenza vaccination in Belgium. We aimed to evaluate this policy from a health care payer perspective by cost-effectiveness analysis in the three specific target groups above, while accounting for effects beyond the target group. Increasing the coverage of influenza vaccination is likely to be cost-effective for pregnant women (median (sic)6589 per quality-adjusted life-year (QALY) gained [(sic)4073-(sic)10,249])...

  12. Empirical Bayes estimates for correlated hierarchical data with overdispersion

    Iddi, Samuel; Molenberghs, Geert; Aregay, Mehreteab; Kalema, George
    An extension of the generalized linear mixed model was constructed to simultaneously accommodate overdispersion and hierarchies present in longitudinal or clustered data. This so-called combined model includes conjugate random effects at observation level for overdispersion and normal random effects at subject level to handle correlation, respectively. A variety of data types can be handled in this way, using different members of the exponential family. Both maximum likelihood and Bayesian estimation for covariate effects and variance components were proposed. The focus of this paper is the development of an estimation procedure for the two sets of random effects. These are necessary...

  13. Maternal cardiovascular profiling in the first trimester of pregnancies complicated with gestation-induced hypertension or fetal growth retardation: a pilot study

    OBEN, Jolien; TOMSIN, Kathleen; Mesens, Tinne; STAELENS, Anneleen; MOLENBERGHS, Geert; GYSELAERS, Wilfried
    Objective: In this study, we determine whether maternal cardiovascular (CV) profiling can detect first trimester differences between women with uncomplicated pregnancies (UP) and those who will develop gestational hypertensive disorders (GHD) or normotensive fetal growth retardation (FGR). Methods: Cardiac, arterial, and venous function were evaluated in 242 pregnant women around 12 weeks of gestation, using impedance cardiography (ICG) and combined electrocardiogram Doppler ultrasonography. After postnatal determination of gestational outcome, first trimester measurements were compared between groups using Mann-Whitney U test for continuous data or Fisher's Exact test for categorical variables (SPSS 20.0). Results: Compared to UP, first trimester aortic flow...

  14. Marginalized multilevel hurdle and zero-inflated models for overdispersed and correlated count data with excess zeros

    KASSAHUN, Wondwosen; NEYENS, Thomas; MOLENBERGHS, Geert; FAES, Christel; VERBEKE, Geert
    Count data are collected repeatedly over time in many applications, such as biology, epidemiology, and public health. Such data are often characterized by the following three features. First, correlation due to the repeated measures is usually accounted for using subject-specific random effects, which are assumed to be normally distributed. Second, the sample variance may exceed the mean, and hence, the theoretical mean-variance relationship is violated, leading to overdispersion. This is usually allowed for based on a hierarchical approach, combining a Poisson model with gamma distributed random effects. Third, an excess of zeros beyond what standard count distributions can predict is...

  15. Trace metals in blood and urine of newborn/mother pairs, adolescents and adults of the Flemish population (2007-2011)

    Baeyens, Willy; Vrijens, Jan; Gao, Yue; Croes, Kim; Schoeters, Greet; Den Hond, Elly; Sioen, Isabelle; BRUCKERS, Liesbeth; NAWROT, Tim; Nelen, Vera; Van den Mieroop, Els; Morrens, Bert; Loots, Ilse; Van Larebeke, Nicolas; Leermakers, Martine
    The Flemish Centre for Environment and Health started with human biomonitoring in 2002 (FLEHS I: 2002-2006). The main goal of the second human biomonitoring cycle (FLEHS II: 2007-2011), was to determine mean values for a large number of pollutants in a representative sample of the general Flemish population. Values for Cd and Pb were updated, and a group of previously undetermined metals and metalloids (As, Mn, Cu and Tl) were included in some of the age groups. In this human biomonitoring program, three different age groups of the general Flemish population were monitored: 255 newborns and their mothers, 210 adolescents...

  16. ST-Segment-Elevation Myocardial Infarction Patients Randomized to a Pharmaco-Invasive Strategy or Primary Percutaneous Coronary Intervention Strategic Reperfusion Early After Myocardial Infarction (STREAM) 1-Year Mortality Follow-Up

    Sinnaeve, Peter R.; Armstrong, Paul W.; Gershlick, Anthony H.; Goldstein, Patrick; Wilcox, Robert; Lambert, Yves; Danays, Thierry; Soulat, Louis; Halvorsen, Sigrun; Rosell Ortiz, Fernando; Vandenberghe, Katleen; Regelin, Anne; Bluhmki, Erich; BOGAERTS, Kris; Van de Werf, Frans
    Background-In the Strategic Reperfusion Early After Myocardial Infarction (STREAM) trial, a pharmaco-invasive (PI) strategy was compared with primary percutaneous coronary intervention (pPCI) in ST-segment-elevation myocardial infarction patients presenting within 3 hours after symptom onset but unable to undergo pPCI within 1 hour. At 30 days, the PI approach was associated with a nominally but nonstatistically significant lower incidence of the composite primary end point of death, shock, congestive heart failure, and reinfarction when compared with pPCI. The aim of the present study was to determine the effect of these strategies on 1-year mortality. Methods and Results-Vital status at 1 year...

  17. Retrospective study of radiotherapy-induced skin reactions in breast cancer patients: Reduced incidence of moist desquamation with a hydroactive colloid gel versus dexpanthenol

    Censabella, Sandrine; Claes, Stefan; Orlandini, Marc; BRAEKERS, Roel; THIJS, Herbert; BULENS, Paul
    Purpose: Dermatitis is a very frequent and distressing side effect of radiation therapy that may necessitate a treatment interruption when evolving towards more severe forms such as moist desquamation (MD). The aim of this study was to compare the efficacy of two topical agents, a dexpanthenol cream vs a hydroactive colloid gel combining absorbing and moisturising properties, in preventing MD in breast cancer patients. Methods: This retrospective study compared two successive groups of breast cancer patients undergoing radiotherapy after breast-sparing surgery between 2008 and 2012. A group of 267 patients applied a 5% dexpanthenol cream on the irradiated zone throughout...

  18. qcML: An Exchange Format for Quality Control Metrics from Mass Spectrometry Experiments

    Walzer, Mathias; Pernas, Lucia Espona; Nasso, Sara; Bittremieux, Wout; Nahnsen, Sven; Kelchtermans, Pieter; Pichler, Peter; van den Toorn, Henk W. P.; Staes, An; Vandenbussche, Jonathan; Mazanek, Michael; Taus, Thomas; Scheltema, Richard A.; Kelstrup, Christian D.; Gatto, Laurent; van Breukelen, Bas; Aiche, Stephan; VALKENBORG, Dirk; Laukens, Kris; Lilley, Kathryn S.; Olsen, Jesper V.; Heck, Albert J. R.; Mechtler, Karl; Aebersold, Ruedi; Gevaert, Kris; Vizcaino, Juan Antonio; Hermjakob, Henning; Kohlbacher, Oliver; Martens, Lennart
    Quality control is increasingly recognized as a crucial aspect of mass spectrometry based proteomics. Several recent papers discuss relevant parameters for quality control and present applications to extract these from the instrumental raw data. What has been missing, however, is a standard data exchange format for reporting these performance metrics. We therefore developed the qcML format, an XML-based standard that follows the design principles of the related mzML, mzIdentML, mzQuantML, and TraML standards from the HUPO-PSI (Proteomics Standards Initiative). In addition to the XML format, we also provide tools for the calculation of a wide range of quality metrics as...

  19. Comment on: Measurement units for antibiotic consumption in outpatients

    Coenen, Samuel; BRUYNDONCKX, Robin; HENS, Niel; AERTS, Marc; Goossens, Herman
    antibiotic consumption; ambulatory care; dose change; measurement unit

  20. Connecting gene expression data from connectivity map and in silico target predictions for small molecule mechanism-of-action analysis

    Ravindranath, Aakash Chavan; PERUALILA-TAN, Nolen; KASIM, Adetayo; Drakakis, Georgios; Liggi, Sonia; Brewerton, Suzanne; Mason, Daniel; Bodkin, Michael; Bhagwat, Aditya; TALLOEN, Willem; Gohlmann, Hinrich; Qstar Consortium; SHKEDY, Ziv; Bender, Andreas
    Integrating gene expression profiles with certain proteins can improve our understanding of the fundamental mechanisms in protein???ligand binding. This paper spotlights the integration of gene expression data and target prediction scores, providing insight into mechanism of action (MoA). Compounds are clustered based upon the similarity of their predicted protein targets and each cluster is linked to gene sets using Linear Models for Microarray Data. MLP analysis is used to generate gene sets based upon their biological processes and a qualitative search is performed on the homogeneous target-based compound clusters to identify pathways. Genes and proteins were linked through pathways for 6...

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