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Search Results: 1 - 10 of 9586 matches for " Gewillig Marc "
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What Limits Cardiac Performance during Exercise in Normal Subjects and in Healthy Fontan Patients?
André La Gerche,Marc Gewillig
International Journal of Pediatrics , 2010, DOI: 10.1155/2010/791291
Abstract: Exercise is an important determinant of health but is significantly reduced in the patient with a univentricular circulation. Normal exercise physiology mandates an increase in pulmonary artery pressures which places an increased work demand on the right ventricle (RV). In a biventricular circulation with pathological increases in pulmonary vascular resistance and/or reductions in RV function, exercise-induced augmentation of cardiac output is limited. Left ventricular preload reserve is dependent upon flow through the pulmonary circulation and this requires adequate RV performance. In the Fontan patient, the reasons for exercise intolerance are complex. In those patients with myocardial dysfunction or other pathologies of the circulatory components, it is likely that these abnormalities serve as a limitation to cardiac performance during exercise. However, in the healthy Fontan patient, it may be the absence of a sub-pulmonary pump which limits normal increases in pulmonary pressures, trans-pulmonary flow requirements and cardiac output. If so, performance will be exquisitely dependent on pulmonary vascular resistance. This provides a potential explanation as to why pulmonary vasodilators may improve exercise tolerance. As has recently been demonstrated, these agents may offer an important new treatment strategy which directly addresses the physiological limitations in the Fontan patient.
What Limits Cardiac Performance during Exercise in Normal Subjects and in Healthy Fontan Patients?
André La Gerche,Marc Gewillig
International Journal of Pediatrics , 2010, DOI: 10.1155/2010/791291
Abstract: Exercise is an important determinant of health but is significantly reduced in the patient with a univentricular circulation. Normal exercise physiology mandates an increase in pulmonary artery pressures which places an increased work demand on the right ventricle (RV). In a biventricular circulation with pathological increases in pulmonary vascular resistance and/or reductions in RV function, exercise-induced augmentation of cardiac output is limited. Left ventricular preload reserve is dependent upon flow through the pulmonary circulation and this requires adequate RV performance. In the Fontan patient, the reasons for exercise intolerance are complex. In those patients with myocardial dysfunction or other pathologies of the circulatory components, it is likely that these abnormalities serve as a limitation to cardiac performance during exercise. However, in the healthy Fontan patient, it may be the absence of a sub-pulmonary pump which limits normal increases in pulmonary pressures, trans-pulmonary flow requirements and cardiac output. If so, performance will be exquisitely dependent on pulmonary vascular resistance. This provides a potential explanation as to why pulmonary vasodilators may improve exercise tolerance. As has recently been demonstrated, these agents may offer an important new treatment strategy which directly addresses the physiological limitations in the Fontan patient. 1. Introduction Exercise is an important determinant of health and provides numerous cardiovascular, psychological, and prognostic benefits [1]. The Fontan operation, and its refinements, have proved a major success with a majority of patients with univentricular malformations now surviving into adulthood with a good quality of life [2]. However, exercise tolerance is significantly reduced and the factors responsible for this exertional limitation are incompletely understood. This paper aims to provide a unique perspective on the limitations of the Fontan circulation by focusing on exercise constraints in a normal biventricular circulation. Rather than describing abnormalities within the components of a Fontan circulation, we will focus on highlighting the importance of that which is missing—a prepulmonary pump. Popular models of exercise physiology have concentrated on the systemic circulation and the left ventricle (LV) as the primary determinant of cardiac output (CO) augmentation during physical exertion [3]. These models are likely to be accurate in patients with heart failure. However, in the healthy subject, there is a large reserve for exercise-induced
Renal Side Effects of Non-Steroidal Anti-Inflammatory Drugs in Neonates
Karel Allegaert,Jan De Hoon,Anne Debeer,Marc Gewillig
Pharmaceuticals , 2010, DOI: 10.3390/ph3020393
Abstract: Non-steroidal anti-inflammatory drugs like ibuprofen or indomethacin are commonly prescribed drugs to induce pharmacologic closure of a patent ductus arteriosus in preterm neonates. Based on a recently published Cochrane meta-analysis, both drugs are equally effective to induce closure. Drug choice can therefore be based on differences in side effects or pharmaco-economic arguments. The current review quantifies the negative impact of either ibuprofen or indomethacin on renal function, including diuresis, glomerular filtration rate and renal tubular function. Both ibuprofen and indomethacin have a quantifiable impact on renal function. However, compared to ibuprofen, the negative impact of indomethacin is more pronounced.
Serial exercise testing in children, adolescents and young adults with Senning repair for transposition of the great arteries
Buys Roselien,Budts Werner,Reybrouck Tony,Gewillig Marc
BMC Cardiovascular Disorders , 2012, DOI: 10.1186/1471-2261-12-88
Abstract: Background Patients with Senning repair for complete transposition of the great arteries (d-TGA) show an impaired exercise tolerance. Our aim was to investigate changes in exercise capacity in children, adolescents and adults with Senning operation. Methods Peak oxygen uptake (peak VO2), oxygen pulse and heart rate were assessed by cardiopulmonary exercise tests (CPET) and compared to normal values. Rates of change were calculated by linear regression analysis. Right ventricular (RV) function was assessed by echocardiography. Results Thirty-four patients (22 male) performed 3.5 (range 3–6) CPET with an interval of ≥ 6 months. Mean age at first assessment was 16.4 ± 4.27 years. Follow-up period averaged 6.8 ± 2 years. Exercise capacity was reduced (p<0.0005) and the decline of peak VO2 ( 1.3 ± 3.7 %/year; p=0.015) and peak oxygen pulse ( 1.4 ± 3.0 %/year; p=0.011) was larger than normal, especially before adulthood and in female patients (p<0.01). During adulthood, RV contractility changes were significantly correlated with the decline of peak oxygen pulse (r= 0.504; p=0.047). Conclusions In patients with Senning operation for d-TGA, peak VO2 and peak oxygen pulse decrease faster with age compared to healthy controls. This decline is most obvious during childhood and adolescence, and suggests the inability to increase stroke volume to the same extent as healthy peers during growth. Peak VO2 and peak oxygen pulse remain relatively stable during early adulthood. However, when RV contractility decreases, a faster decline in peak oxygen pulse is observed.
Collaboratively charting the gene-to-phenotype network of human congenital heart defects
Roland Barriot, Jeroen Breckpot, Bernard Thienpont, Sylvain Brohée, Steven Van Vooren, Bert Coessens, Leon-Charles Tranchevent, Peter Van Loo, Marc Gewillig, Koenraad Devriendt, Yves Moreau
Genome Medicine , 2010, DOI: 10.1186/gm137
Abstract: We built on the recent advances in Wiki-based technologies to develop a collaborative knowledge base and gene prioritization portal aimed at mapping genes and genomic regions, and untangling their relations with corresponding human phenotypes, congenital heart defects (CHDs). This portal is not only an evolving community repository of current knowledge on the genetic basis of CHDs, but also a collaborative environment for the study of candidate genes potentially implicated in CHDs - in particular by integrating recent strategies for the statistical prioritization of candidate genes. It thus serves and connects the broad community that is facing CHDs, ranging from the pediatric cardiologist and clinical geneticist to the basic investigator of cardiogenesis.This study describes the first specialized portal to collaboratively annotate and analyze gene-phenotype networks. Of broad interest to the biological community, we argue that such portals will play a significant role in systems biology studies of numerous complex biological processes.CHDWiki is accessible at http://www.esat.kuleuven.be/~bioiuser/chdwiki webciteRecently, Wiki technology - inspired by the well-known Wikipedia encyclopedia - has been proposed as a potential strategy for the collaborative development of biological knowledge bases [1-6]. Although a 'Wikipedia for Genes' is likely to emerge, a number of challenges remain. First, classical Wiki technology in itself (based on free text) is unsuitable for developing genetic knowledge bases because of the imperative need for structured information. Hence, Wiki platforms for genetic knowledge bases need to provide a strong framework for integration with classical database technology. Wikiproteins already implements this need at a high level by abstractly linking concepts, such as proteins and biological processes [1]. Second, and probably foremost, each community uses specific terminology, has specific goals, and uses specific data and tools. Such specificit
Response of the oxygen pulse during exercise in children with atrial repair for transposition of the great arteries
Buys R, Dockx K, Gewillig M, Reybrouck T
Research Reports in Clinical Cardiology , 2012, DOI: http://dx.doi.org/10.2147/RRCC.S33328
Abstract: ponse of the oxygen pulse during exercise in children with atrial repair for transposition of the great arteries Original Research (870) Total Article Views Authors: Buys R, Dockx K, Gewillig M, Reybrouck T Published Date November 2012 Volume 2012:3 Pages 57 - 62 DOI: http://dx.doi.org/10.2147/RRCC.S33328 Received: 26 April 2012 Accepted: 22 June 2012 Published: 30 November 2012 Roselien Buys,1,2,* Kimberly Dockx,1,* Marc Gewillig,3 Tony Reybrouck1,2 1Department of Rehabilitation Sciences, 2Department of Cardiovascular Rehabilitation, University of Leuven, Leuven, Belgium; 3Department of Pediatric Cardiology, University Hospital Gasthuisberg, Leuven, Belgium *These authors contributed equally to this paper Background: The oxygen pulse equals stroke volume times arterial–venous oxygen difference and is calculated by dividing oxygen uptake (VO2) by heart rate (HR). In children with a Senning repair for the transposition of the great arteries (TGA), the response of both HR and VO2 to exercise is impaired. Our aim was to assess the oxygen pulse response during exercise in patients who underwent a Senning operation, comparing it with healthy controls. Methods: Twenty-one children with a Senning repair (mean age 12.5 ± 1.7 years) and a control group of 31 healthy children (mean age 13.2 ± 2.0 years) performed a graded maximal exercise test on a treadmill, during which HR and VO2 were measured. Oxygen pulse was calculated by dividing VO2 by HR. Right ventricular function was quantitatively assessed by cardiac ultrasound. Results: Senning patients had a lower peak oxygen pulse than the control (P = 0.0024) (8.45 ± 1.90 mL beats-1 versus 11.7 ± 3.93 mL beats-1), as with the peak VO2 (P < 0.001) (35.8 ± 5.67 mL min-1 kg-1 versus 46.6 ± 8.02 mL min-1 kg-1) and peak HR (171 ± 14 beats min-1 versus 188 ± 11 beats min-1). During submaximal exercise, oxygen pulse and VO2 were also significantly lower in Senning patients when compared to the control group (P = 0.027). In seven Senning patients (33%), the oxygen pulse did not increase any further after the first exercise levels. These patients had lower right ventricular function compared to the control group (P = 0.04). Conclusion: Children with a Senning repair for TGA have a reduced peak VO2, peak HR, and peak oxygen pulse. Their oxygen pulse starts off at a lower level, reaches its plateau earlier, and is related to right ventricular function. This variable can be considered a complementary parameter to assess cardiovascular exercise performance.
Response of the oxygen pulse during exercise in children with atrial repair for transposition of the great arteries
Buys R,Dockx K,Gewillig M,Reybrouck T
Research Reports in Clinical Cardiology , 2012,
Abstract: Roselien Buys,1,2,* Kimberly Dockx,1,* Marc Gewillig,3 Tony Reybrouck1,21Department of Rehabilitation Sciences, 2Department of Cardiovascular Rehabilitation, University of Leuven, Leuven, Belgium; 3Department of Pediatric Cardiology, University Hospital Gasthuisberg, Leuven, Belgium*These authors contributed equally to this paperBackground: The oxygen pulse equals stroke volume times arterial–venous oxygen difference and is calculated by dividing oxygen uptake (VO2) by heart rate (HR). In children with a Senning repair for the transposition of the great arteries (TGA), the response of both HR and VO2 to exercise is impaired. Our aim was to assess the oxygen pulse response during exercise in patients who underwent a Senning operation, comparing it with healthy controls.Methods: Twenty-one children with a Senning repair (mean age 12.5 ± 1.7 years) and a control group of 31 healthy children (mean age 13.2 ± 2.0 years) performed a graded maximal exercise test on a treadmill, during which HR and VO2 were measured. Oxygen pulse was calculated by dividing VO2 by HR. Right ventricular function was quantitatively assessed by cardiac ultrasound.Results: Senning patients had a lower peak oxygen pulse than the control (P = 0.0024) (8.45 ± 1.90 mL beats-1 versus 11.7 ± 3.93 mL beats-1), as with the peak VO2 (P < 0.001) (35.8 ± 5.67 mL min-1 kg-1 versus 46.6 ± 8.02 mL min-1 kg-1) and peak HR (171 ± 14 beats min-1 versus 188 ± 11 beats min-1). During submaximal exercise, oxygen pulse and VO2 were also significantly lower in Senning patients when compared to the control group (P = 0.027). In seven Senning patients (33%), the oxygen pulse did not increase any further after the first exercise levels. These patients had lower right ventricular function compared to the control group (P = 0.04).Conclusion: Children with a Senning repair for TGA have a reduced peak VO2, peak HR, and peak oxygen pulse. Their oxygen pulse starts off at a lower level, reaches its plateau earlier, and is related to right ventricular function. This variable can be considered a complementary parameter to assess cardiovascular exercise performance.Keywords: transposition of the great arteries, Senning repair, oxygen pulse, cardiopulmonary exercise testing
Editorial Article for the Journal of Microscopy Research  [PDF]
Marc Porti
Microscopy Research (MR) , 2013, DOI: 10.4236/mr.2013.12002
Abstract: Editorial; MR
Ionic Group Derivitized Nano Porous Carbon Electrodes for Capacitive Deionization  [PDF]
Marc Andelman
Journal of Materials Science and Chemical Engineering (MSCE) , 2014, DOI: 10.4236/msce.2014.23002
Abstract:

Capacitance for electrostatic adsorption forms primarily within a Debye length of the electrode surface. Capacitive carbon electrodes were derivatized with ionic groups by means of adsorbing a surfactant in order to test the theory that attached ionic groups would exclude co-ions and increase coulombic efficiency without the need for an added charge barrier membrane. It has been discovered that capacitive electrodes surface derivatized with ionic groups become polarized and intrinsically more coulombically efficient.

Soldner Had Found in 1802 the Deflection of the Light by the Sun as the General Relativity Shows  [PDF]
Marc Mignonat
Journal of Modern Physics (JMP) , 2018, DOI: 10.4236/jmp.2018.98095
Abstract: Systematically, it is written in the literature that only the general relativity (GR) allows finding the just value of the deflection of the light by the sun. Yet, we noted, by reading over the original text of SOLDNER of 1801: “Ueber die Ablenkung eines Lichtstrals von seiner geradlinigen Bewegung, durch die Attraktion eines Weltkörpers, the welchem er nahe vorbei geht” (that we think it is important to put in English in full in Appendix) that, contrary to what we read since about 100 years, he found the right value. Soldner had started from a Newtonian gravitational calculation and, with the value of 1801, find 1.64”. This calculation, with the actual values, allows finding the right value of 1.752”. There are reasons to explain the wrong calculations which we usually make. However, there is no epistemological reason for questioning the general relativity. Some observations are only explained by the GR. But the Newtonian calculations are much simpler. We can continue to say that the theory of Newton is incomplete but we cannot say it is false.
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