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See detailContribution of Mutant Analysis to the Understanding of Enzyme Catalysis: The Case of Class a Beta-Lactamases
Matagne, André ULg; Frère, Jean-Marie ULg

in Biochimica et Biophysica Acta (1995), 1246(2), 109-27

Class A beta-lactamases represent a family of well studied enzymes. They are responsible for many antibiotic resistance phenomena and thus for numerous failures in clinical chemotherapy. Despite the facts ... [more ▼]

Class A beta-lactamases represent a family of well studied enzymes. They are responsible for many antibiotic resistance phenomena and thus for numerous failures in clinical chemotherapy. Despite the facts that five structures are known at high resolution and that detailed analyses of enzymes modified by site-directed mutagenesis have been performed, their exact catalytic mechanism remains controversial. This review attempts to summarize and to discuss the many available data. [less ▲]

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See detailContribution of MX dynamin, oligoadenylate synthetase, and protein kinase R to anti-paramyxovirus activity of type-1 interferons in vitro
Leroy, M.; Baise, Etienne ULg; Pire, G. et al

in American Journal of Veterinary Research (2007), 68

OBJECTIVE: To determine the contribution of MX dynamin, oligoadenylate synthetase (OAS), and double-stranded RNA-dependent protein kinase R (PKR) to the antiviral effects of type 1 interferons (IFNs ... [more ▼]

OBJECTIVE: To determine the contribution of MX dynamin, oligoadenylate synthetase (OAS), and double-stranded RNA-dependent protein kinase R (PKR) to the antiviral effects of type 1 interferons (IFNs) against bovine parainfluenza-3 virus (PI-3V) infection of Vero cells. SAMPLE POPULATION: Vero cell cultures. PROCEDURES: PI-3V yield was first compared between control and transfected type 1 IFNs-incompetent Vero cells expressing recombinant OAS or MX proteins. Afterwards, phosphorylation of eukaryotic initiation factor 2 alpha (eIF2alpha) was used to scale the degree of PKR activation upon infection of Vero cells by PI-3V. RESULTS: Overexpression of OAS did not result in significantly decreased viral replication. Phosphorylated eIF2alpha forms, the hallmark of PKR activation, were not increased in IFNalpha-primed infected Vero cells. Although human MXA contributed to partial blockade of replication of bovine PI-3V, the antiviral effect was not as strong as that of IFNalpha. CONCLUSIONS AND CLINICAL RELEVANCE: The powerful anti-Paramyxovirus activity of type 1 IFNs is mediated by noncanonic pathways. [less ▲]

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See detailContribution of nanoclays to the barrier properties of a model proton exchange membrane for fuel cell application
Thomassin, Jean-Michel ULg; Pagnoulle, Christophe; Caldarella, Giuseppe ULg et al

in Journal of Membrane Science (2006), 270(1-2), 50-56

Direct methanol fuel cells (DMFCs) that use a proton exchange membrane (PEM) as electrolyte, is a promising alternative source of energy for the future. However, methanol crossover from the anodic side to ... [more ▼]

Direct methanol fuel cells (DMFCs) that use a proton exchange membrane (PEM) as electrolyte, is a promising alternative source of energy for the future. However, methanol crossover from the anodic side to the cathodic one is a major problem in DMFC. Proper dispersion of layered silicates within the fuel cell membrane has been proposed as a strategy for improving the barrier properties of the membrane. The validity of this approach has been tested in case of a model membrane consisting of phosphotungstic acid doped poly(vinyl alcohol). A solvent casting technique has been used, which allows the nanofiller to be delaminated by an ultrasonic pre-treatment, as confirmed by TEM and XRD analysis. The layered silicates have a favourable impact on the methanol permeability, whose the decrease overcompensates some loss in ionic conductivity. [less ▲]

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See detailContribution of new radiocarbon dates to track the impact of past anthropogenic disturbances on current vegetation in Central Africa
Morin-Rivat, Julie ULg; Gillet, Jean-François ULg; Bourland, Nils ULg et al

Poster (2012, July)

Introduction: Understanding current Central Africa vegetation patterns faces the scarcity of data about their past evolution. However, a growing hypothesis suggests that past human activities could have ... [more ▼]

Introduction: Understanding current Central Africa vegetation patterns faces the scarcity of data about their past evolution. However, a growing hypothesis suggests that past human activities could have had a substantial influence on vegetation (Van Gemerden et al. 2003, Brncic et al. 2009). Indeed, by creating large openings (fig. 1), they might have triggered the expansion of light-demanding species currently suffering from a lack of regeneration. This lack of saplings could have been caused by the change in land use since colonization with the sedentarization of shifting cultivators. Aim of the study: To investigate the potential relationship between past anthropogenic disturbances and present vegetation. Material & methods: Fieldworks combining anthracological and ecological approaches have been undertaken in Northern Congo and South-Eastern Cameroon (fig. 2). We excavated thirty 150-200 cm deep pits under different forest covers and vegetation types to identify evidences of past human presence (i.e potsherds, fig. 3, slags from metallurgy, anthropogenic pieces of charcoals and anthropophilous charred seeds). Charcoals and seeds (oil palm Elaeis guineensis, fig. 4, Canarium schweinfurthii) in combination with artifacts have been dated. Results: A set of 38 new radiocarbon dates ranging from 15,200 cal BP to present time have been obtained. They confirm the existence of important past fire events in a region where natural ones seldom occur. Together with artifacts, our findings support the few already available dates documenting evidences of past human activities in Central African rainforests. On the 36 most recent dates (fig. 5), the majority belongs to the 2,300-1,400 cal BP period (61%). The whole semi-deciduous forest zone is concerned by this period of intense disturbances with a high rate of fragmentation. It follows the last great arid phase ca. 2,500 cal BP and might be linked to the iron workers expansion. Another pool of dates between 650 and 250 cal BP (33%) associated with potsherds might be correlated to a dry phase contemporary to the Little Ice Age in Europe. That last group of dates points out the potential positive impact of anthropogenic disturbances connected to a dry climatic event on light-demanding species populations. Indeed, this is consistent with the fact that most of current light-demanding trees have a higher number of stems around 100 cm dbh. Conclusion: Our multidisciplinary approach allowed new insights into the link between human history and vegetation dynamics in Central Africa. Further investigations should be conducted to go deeper into the understanding of the evolution of Central African rainforests and to improve the management of currently logged light-demanding species resulting from the LIA period. Thirty new dates from sixteen soil profiles are forthcoming. References: Brncic T., Willis M., K. J., Harris D. J., Telfer M. W. & Bailey M. W. 2009. Fire and climate change impacts on lowland forest composition in northern Congo during the last 2580 years from palaeoecological analyses of a seasonally flooded swamp. The Holocene, 19, 79-89. Reimer P. J., Baillie M. G. L., Bard E., Bayliss A., Beck J. W., Blackwell P. G., Bronk Ramsey C., Buck C. E., Burr G. S., Edwards R. L., Friedrich M., Grootes P. M., Guilderson T. P., Hajdas I., Heaton T. J., Hogg A. G., Hughen K. A., Kaiser K. F., Kromer B., McCormac F. G., Manning S. W., Reimer R. W., Richards D. A., Southon J.R., Talamo S., Turney C. S. M., van der Plicht J., & Weyhenmeyer, C. E. 2009. IntCal09 and Marine09 radiocarbon age calibration curves, 0-50,000 years cal BP. Radiocarbon, 51(4), 1111-1150. Van Gemerden B. S., Olff H., Parren M. P. E, Bongers F. 2003. The pristine rain forest? Remnants of historical human impacts on current tree species composition and diversity. Journal of Biogeography, 30, 1381-1390. [less ▲]

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See detailCONTRIBUTION OF NEW TECHNIQUES TO STUDY GAIT IN THE OLDERS
GILLAIN, Sophie ULg; Petermans, Jean ULg

in Annals of Physical and Rehabilitation Medicine (2013), 56

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See detailContribution of Peripheral Blood Pooling to Central Hemodynamic Disturbances During Endotoxin Insult in Intact Dogs
D'Orio, Vincenzo ULg; Wahlen, C.; Naldi, Marco ULg et al

in Critical Care Medicine (1989), 17(12), 1314-9

The aim of the present study was to determine possible effects of Escherichia coli endotoxin on peripheral vascular compliance and relate them to concomitant central hemodynamic disturbances. Endotoxin ... [more ▼]

The aim of the present study was to determine possible effects of Escherichia coli endotoxin on peripheral vascular compliance and relate them to concomitant central hemodynamic disturbances. Endotoxin was infused at 0.25 micrograms/kg.min during 2 h in six anesthetized dogs, while six additional animals served as controls. Vascular compliance of the systemic circulation was calculated in intact animals from the changes in CVP after known changes in systemic blood volume. In control dogs, vascular compliance averaged 2.3 ml/mm Hg.kg body weight. During slow endotoxin infusion, cardiovascular effects were measurable only after a certain period of time had elapsed from the start of endotoxin insult and consisted of hypotension associated with systemic vasodilation. Systemic BP decreased gradually from 124 to 68 mm Hg while vascular compliance was finally increased by 100%, when compared to control values. This latter rise was responsible for a reduction in the cardiac preloads. Pulmonary wedge pressure and CVP were decreased from 7.1 to 3.4 and from 4.5 to 2.6 mm Hg, respectively. However, parallel to the decrease in left ventricular preload, endotoxin induced a progressive decrease in left ventricular afterload. Because of the balance in ventricular loading, cardiac output remained almost unchanged. After volume loading (dextran 30 ml/kg), cardiac output was remarkably increased from 3.28 to 6.24 L/min.m2 while peripheral vasodilation was not affected by this maneuver. It is concluded that low dose endotoxin infusion induces in dogs a hemodynamic pattern similar to human sepsis. The left ventricular loading changes are related to an enhanced systemic vascular compliance from 2.3 to 4.5 ml/mm Hg.kg. High flow shock state is encountered provided peripheral blood pooling is compensated by adequate volume replacement. [less ▲]

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See detailContribution of Pet Scanning to the Evaluation of Abdominal Aortic Aneurysm
Sakalihasan, Natzi ULg; Hustinx, Roland ULg; Limet, Raymond ULg

in Seminars in Vascular Surgery (2004), 17(2), 144-53

The size of abdominal aortic aneurysms (AAA) is the most usual predictor of the risk for rupture. Because chronic metalloproteinases production and activation by inflammatory cells causes degradation of ... [more ▼]

The size of abdominal aortic aneurysms (AAA) is the most usual predictor of the risk for rupture. Because chronic metalloproteinases production and activation by inflammatory cells causes degradation of elastin and collagen in the aneurysmal wall, the detection of an increased metabolic process preceding fissuration and rupture could be a more sensitive predictor of rupture risk. We investigated the metabolic activity of the aneurysmal wall by whole-body positron emission tomography (PET) in 26 patients with a documented AAA (mean diameter 63 mm, extremes 45 mm and 78 mm). A positive (18)F-fluorodeoxyglucose ((18)F-FDG) uptake at the level of the AAA was observed in 38% of the cases (10 of 26 patients). Nine of these 10 patients required emergent or urgent aneurysmectomy for ruptured (n = 1), leaking (n = 1), rapidly expanding (n = 2), or painful (n = 5) aneurysms; the negative (18)F-FDG uptake patients had a more benign course. This preliminary study suggests a possible correlation between (18)F-FDG uptake by the aneurysm wall and the triggering of processes leading to rupture. The (18)F-FDG uptake in the aneurysm wall may correspond to the accumulation of inflammatory cells responsible for the production and activation of degrading enzymes. PET scan seems useful in high-risk patients. Positive PET imaging in these cases would help us to decide to proceed with surgery, despite factors favoring a surveillance strategy. [less ▲]

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See detailContribution of platelet glycoprotein VI to the thrombogenic effect of collagens in fibrous atherosclerotic lesions.
Cosemans, Judith M E M; Kuijpers, Marijke J E; Lecut, Christelle ULg et al

in Atherosclerosis (2005), 181(1), 19-27

Collagens (types I and III) are among the strongest thrombus-forming components of the vascular subendothelium. We compared the thrombogenic effects of four collagen-containing advanced atherosclerotic ... [more ▼]

Collagens (types I and III) are among the strongest thrombus-forming components of the vascular subendothelium. We compared the thrombogenic effects of four collagen-containing advanced atherosclerotic lesions with those of purified types I and III collagen fibers. Cell-free homogenates from the human plaques effectively promoted platelet adhesion and aggregate formation under high-shear flow conditions, as well as exposure of procoagulant phosphatidylserine (PS) on platelets. With all plaques, blocking of the glycoprotein VI (GPVI) receptor for collagen abolished aggregation and PS exposure. Blocking of platelet ADP receptors resulted in similar, but less complete inhibitory effects. Type I collagen was more potent than type III collagen in inducing aggregation and PS exposure under flow, via stimulation of GPVI and ADP receptors. Type I collagen also more strongly enhanced thrombin generation with platelets and tissue factor, again via GPVI activation and PS exposure. The plaque material enhanced thrombin generation, partly due to the presence of tissue factor and partly via GPVI and ADP receptors. Together, these results indicate that in advanced plaques collagen type I is a major trigger of thrombus formation and PS exposure, acting via GPVI and ADP release, while tissue factor directly enhances coagulation. [less ▲]

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See detailContribution of polyalky(meth)acrylates to the design of PVC melt viscosity
Vankan, R.; Fayt, Roger; Jérôme, Robert ULg et al

in Polymer Engineering & Science (1996), 36(12), 1675-1684

The shear viscosity of poly(vinylchloride) (PVC) at 200°C can be decreased by at least one order of magnitude by the addition of as little as 5 wt% poly n-alkyl-(meth)acrylates (PMA) of a much lower ... [more ▼]

The shear viscosity of poly(vinylchloride) (PVC) at 200°C can be decreased by at least one order of magnitude by the addition of as little as 5 wt% poly n-alkyl-(meth)acrylates (PMA) of a much lower dynamic viscosity than PVC. For this effect to be observed, the polymeric additive must be immiscible with PVC at 200°C. The average size of the dispersed phases is observed in the range of 0.5 to 5 m; size fluctuation in this domain has no significant effect. When these conditions are met, there is a linear increase in the shear viscosity ratio blend/PVC from 0.2 to 1.0 with increasing logarithmic values of the dynamic viscosity ratio of the additive over PVC [(log(/)) from -4 to -1]. [less ▲]

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See detailContribution of positron emission tomography in pleural disease.
Duysinx, Bernard ULg; Corhay, Jean-Louis ULg; Larock, Marie-Paule ULg et al

in Revue des Maladies Respiratoires (2010), 27(8), 47-53

INTRODUCTION: Positron emission tomography (PET) now plays a clear role in oncology, especially in chest tumours. We discuss the value of metabolic imaging in characterising pleural pathology in the light ... [more ▼]

INTRODUCTION: Positron emission tomography (PET) now plays a clear role in oncology, especially in chest tumours. We discuss the value of metabolic imaging in characterising pleural pathology in the light of our own experience and review the literature. BACKGROUND: PET is particularly useful in characterising malignant pleural pathologies and is a factor of prognosis in mesothelioma. Metabolic imaging also provides clinical information for staging lung cancer, in researching the primary tumour in metastatic pleurisy and in monitoring chronic or recurrent pleural pathologies. CONCLUSIONS: PET should therefore be considered as a useful tool in the diagnosis of liquid or solid pleural pathologies. [less ▲]

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See detailContribution of postero-anterior cephalometry in obstructive sleep apnea.
POIRRIER, Anne-Lise ULg; Pire, Sylvie; Raskin, Sylviane et al

in The Laryngoscope (2012), 122(10), 2350-4

OBJECTIVES/HYPOTHESIS: Lateral cephalometry has been widely used to characterize facial and maxillary morphology in obstructive sleep apnea (OSA) patients. It is a useful tool to assess orthodontic and ... [more ▼]

OBJECTIVES/HYPOTHESIS: Lateral cephalometry has been widely used to characterize facial and maxillary morphology in obstructive sleep apnea (OSA) patients. It is a useful tool to assess orthodontic and maxillofacial procedures, but transverse dimensions of the airway (e.g., nasal framework) have not been well described yet by cephalometry. We explored whether postero-anterior cephalometry could refine the analysis of the facial morphology, with a special attention paid to nasal morphology. We validated cephalometric measurements relevant to the diagnosis of OSA. STUDY DESIGN: Controlled study. METHODS: We explored postero-anterior and lateral cephalometric bony structures in OSA patients and in control subjects to determine which were predictive of an association with OSA. Healthy volunteers paired for age and sex to OSA patients underwent polysomnography and cephalometry. Data were analyzed by Shapiro-Wilk, Fisher, Wilcoxon, and paired t tests where appropriate. RESULTS: Nasal fossae and maxillary bone proportions were positively and independently associated with the absence of OSA. Measurements of maxillary width, nasal fossae angle, and anterior skull base contributed to the characterization of OSA patients. CONCLUSIONS: Postero-anterior cephalometry is an easy, rapid, informative, and reliable technique, which is complementary to the lateral cephalometry in the assessment of OSA patients. Our study may also suggest the negative impact of the nasal resistance on the upper airway resistance in sleep disorders. [less ▲]

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See detailThe contribution of primary care to health and health systems in low- and middle-income countries: a critical review of major primary care initiatives.
Kruk, Margaret Elizabeth; Porignon, Denis ULg; Rockers, Peter C. et al

in Social science & medicine (1982) (2010), 70(6), 904-11

It has been 30 years since the Declaration of Alma Ata. During that time, primary care has been the central strategy for expanding health services in many low- and middle-income countries. The recent ... [more ▼]

It has been 30 years since the Declaration of Alma Ata. During that time, primary care has been the central strategy for expanding health services in many low- and middle-income countries. The recent global calls to redouble support for primary care highlighted it as a pathway to reaching the health Millennium Development Goals. In this systematic review we described and assessed the contributions of major primary care initiatives implemented in low- and middle-income countries in the past 30 years to a broad range of health system goals. The scope of the programs reviewed was substantial, with several interventions implemented on a national scale. We found that the majority of primary care programs had multiple components from health service delivery to financing reform to building community demand for health care. Although given this integration and the variable quality of the available research it was difficult to attribute effects to the primary care component alone, we found that primary care-focused health initiatives in low- and middle-income countries have improved access to health care, including among the poor, at reasonably low cost. There is also evidence that primary care programs have reduced child mortality and, in some cases, wealth-based disparities in mortality. Lastly, primary care has proven to be an effective platform for health system strengthening in several countries. Future research should focus on understanding how to optimize the delivery of primary care to improve health and achieve other health system objectives (e.g., responsiveness, efficiency) and to what extent models of care can be exported to different settings. [less ▲]

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See detailThe contribution of processing fluency to preference : a comparison with familiarity-based recognition
Willems, Sylvie ULg; Van der Linden, Martial ULg; Bastin, Christine ULg

in European Journal of Cognitive Psychology (2007), 19(1), 119-140

There is a great deal of evidence supporting the idea that, when a stimulus is processed fluently, it is more likely to be judged as pleasant. However, this influence of fluency on preference judgement ... [more ▼]

There is a great deal of evidence supporting the idea that, when a stimulus is processed fluently, it is more likely to be judged as pleasant. However, this influence of fluency on preference judgement seems to depend on several experimental conditions. So we tried to better understand these conditions via a comparison with recognition and by manipulating some aspects of the procedure (test format) and material (similarity and figure-ground contrast of the stimuli). Two experiments showed that some conditions maximally induce the use of processing fluency in a preference judgement, as in a recognition task. We discuss the implications of these findings for the well-documented discrepancy-attribution hypothesis (Whittlesea [less ▲]

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See detailThe contribution of recollection and familiarity to recognition memory : A study of the effects of test format and aging
Bastin, Christine ULg; Van der Linden, Martial ULg

in Neuropsychology (2003), 17(1), 14-24

Whether the format of a recognition memory task influences the contribution of recollection and familiarity to performance is a matter of debate. The authors investigated this issue by comparing the ... [more ▼]

Whether the format of a recognition memory task influences the contribution of recollection and familiarity to performance is a matter of debate. The authors investigated this issue by comparing the performance of 64 young (mean age = 21.7 years; mean education = 14.5 years) and 62 older participants (mean age = 64.4 years; mean education = 14.2 years) on a yes–no and a forced-choice recognition task for unfamiliar faces using the remember– know–guess procedure. Familiarity contributed more to forced-choice than to yes–no performance. Moreover, older participants, who showed a decrease in recollection together with an increase in familiarity, performed better on the forced-choice task than on the yes–no task, whereas younger participants showed the opposite pattern. [less ▲]

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See detailThe contribution of recollection and familiarity to recognition memory performance in chronic pain patients
Grisart, Jacques; Van der Linden, Martial ULg; Bastin, Christine ULg

in Behaviour research and therapy (2007), 45

This study examines the selective impact of chronic pain on memory functioning in a recognition task. Thirty chronic pain patients and 30 healthy control subjects performed a yes–no word recognition test ... [more ▼]

This study examines the selective impact of chronic pain on memory functioning in a recognition task. Thirty chronic pain patients and 30 healthy control subjects performed a yes–no word recognition test. The contribution of recollection and familiarity to both groups’ performance was compared by means of the Remember/Know (R/K) procedure, which distinguishes recognition based on the recollection of the encoding episode (R responses) and recognition accompanied by a feeling of familiarity (K responses). Chronic pain patients showed a decrease in recollection together with an increase in familiarity: indeed, they reported less R and more K responses than control subjects. This pattern of performance was not related to the overall recognition ability. These findings are consistent with the hypothesis of the attentional cost of chronic pain, suggesting a selective impact of chronic pain on the most attention-demanding cognitive processes, such as recollection. This study emphasises the relevance of specific procedures distinguishing the underlying components of memory functioning rather than solely global indicators. [less ▲]

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See detailContribution of reticular nuclei in the pathophysiology of parkinsonian rigidity
Delwaide, Paul ULg; PEPIN, Jean-Louis ULg; MAERTENS DE NOORDHOUT, Alain ULg

in Narabayashi, H.; Nagatsu, T.; yanagisawa, N. (Eds.) et al Advances in Neurology - Vol 60 (1993)

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