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See detailPiracetam Inhibits The Lipid-Destabilising Effect Of The Amyloid Peptide A Beta C-Terminal Fragment
Mingeot-Leclercq, Mp.; Lins, Laurence ULg; Bensliman, M. et al

in Biochimica et Biophysica Acta-Biomembranes (2003), 1609(1), 28-38

Amyloid peptide (Abeta) is a 40/42-residue proteolytic fragment of a precursor protein (APP), implicated in the pathogenesis of Alzheimer's disease. The hypothesis that interactions between Abeta ... [more ▼]

Amyloid peptide (Abeta) is a 40/42-residue proteolytic fragment of a precursor protein (APP), implicated in the pathogenesis of Alzheimer's disease. The hypothesis that interactions between Abeta aggregates and neuronal membranes play an important role in toxicity has gained some acceptance. Previously, we showed that the C-terminal domain (e.g. amino acids 29-42) of Abeta induces membrane permeabilisation and fusion, an effect which is related to the appearance of non-bilayer structures. Conformational studies showed that this peptide has properties similar to those of the fusion peptide of viral proteins i.e. a tilted penetration into membranes. Since piracetam interacts with lipids and has beneficial effects on several symptoms of Alzheimer's disease, we investigated in model membranes the ability of piracetam to hinder the destabilising effect of the Abeta 29-42 peptide. Using fluorescence studies and 31P and 2H NMR spectroscopy, we have shown that piracetam was able to significantly decrease the fusogenic and destabilising effect of Abeta 29-42, in a concentration-dependent manner. While the peptide induced lipid disorganisation and subsequent negative curvature at the membrane-water interface, the conformational analysis showed that piracetam, when preincubated with lipids, coats the phospholipid headgroups. Calculations suggest that this prevents appearance of the peptide-induced curvature. In addition, insertion of molecules with an inverted cone shape, like piracetam, into the outer membrane leaflet should make the formation of such structures energetically less favourable and therefore decrease the likelihood of membrane fusion. [less ▲]

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See detailPiracetam-Induced Changes To Membrane Physical-Properties - A Combined Approach By P-31 Nuclear-Magnetic-Resonance And Conformational-Analysis
Peuvot, J.; Schanck, A.; Deleers, M. et al

in Biochemical Pharmacology (1995), 50(8), 1129-34

Piracetam, Nootropil (2-oxo-1-pyrrolidine acetamide), is a drug promoting erythrocyte deformability. To establish the mode of action of this compound, we have investigated its influence on the ... [more ▼]

Piracetam, Nootropil (2-oxo-1-pyrrolidine acetamide), is a drug promoting erythrocyte deformability. To establish the mode of action of this compound, we have investigated its influence on the organization of model phospholipid membranes. 31P NMR data show that the drug induces a structural modification in liposomes made of phosphatidylcholine and phosphatidylethanolamine. Our conformational analysis results have allowed the interpretation of the effect of piracetam on these model membranes: the specific interaction between the drug molecules and the phosphate headgroups induces a new organization of the lipids favouring formation of mobile drug-phospholipid complexes that exhibit an isotropic-type signal in the 31P NMR spectra. [less ▲]

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See detailPiracy prevention and the pricing of information goods
Cremer, Helmuth; Pestieau, Pierre ULg

in Information Economics and Policy (2009), (21), 34-42

This paper studies the effects of piracy on prices and welfare and determines the optimal enforcement policy. A monopolist sells an information good at a non-linear price in two versions designed for two ... [more ▼]

This paper studies the effects of piracy on prices and welfare and determines the optimal enforcement policy. A monopolist sells an information good at a non-linear price in two versions designed for two types of consumers with different willingness to pay. Consumers with low willingness to pay consumers can copy the good at some cost and with some quality loss. High valuation customers cannot engage in full-fledged piracy. However, they can consume the version designed for the other customer type. We show that copying or piracy may be welfare enhancing because it enables a good to be provided to individuals with a low willingness to pay without undermining the producing firm’s ability to finance the development cost via the pricing scheme applied to high valuation consumers. There are then three levels of piracy control. The highest is that chosen by the private monopoly. The next level is the one chosen by a welfare-maximizing monopoly. The lowest level, which can be zero, is the level of control chosen by the public authority when the good is sold (and priced) by a profit-maximizing monopoly. ! 2008 Elsevier B.V. All rights reserved. [less ▲]

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See detailPirandello far from Nature?: A reading of I vecchi e i giovani Focusing on Landscape
de Seta, Ilaria ULg

in Pirandello Studies (2007), 27

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See detailPiranesi's Haunt: the fascination for paradoxical spaces in the aesthetics of architecture today.
Dawans, Stéphane ULg

Conference (2013, July 24)

Rem Koolhaas, a major provocative figure on the global scene of architecture theory since 1978—when he published Delirious New York—clearly bases his rhetorics on obsessive patterns such as the loop or ... [more ▼]

Rem Koolhaas, a major provocative figure on the global scene of architecture theory since 1978—when he published Delirious New York—clearly bases his rhetorics on obsessive patterns such as the loop or intertwined spaces claimed as Piranesian. This is notably the case in Euralille, this large urban complex meant to revive the old French industrial city, where the reference to the 18th-century engraver is most obvious in a large destructured hall, in an accumulation of stairs, footbridges and escalators which, on the way out of the railway station, are deliberate reminders of the engravings of imaginary jails that emerged from the Venetian artist’s brain. Of course engraving, painting, photography and cinema have been using similar processes for quite some time to create a dizzying sensation with the spectator. Those high and low angle views of entangled planes based on seemingly paradoxical geometry denote a willingness to use the features of the sublime to create mixed feelings of fascination and anguish or to remind mankind of their mortal condition, in other words, of their finite nature. Romanticism is known to have been quite inspired by this dramatic force. Yet what appeals to us in this revival of an aesthetics of the sublime is that it now crosses a new border as it imposes itself into public space, into city life. If films or 3ds digital games attract informed and consenting viewers, Piranesian spaces—Koolhaas also speaks of Junkspace—impose themselves to all and dramatize the modern man’s anguish without the slightest concern for his opinion. What kinds of ethos and of pathos underlie this contemporary theory of architectural and urban spaces inspired by Piranesi’s or Escher’s engravings? What literary strategies are at play? Why can the same obsessive spatial leitmotivs be found in plane puzzles, in films and in the new urban scenery? What does this aesthetics tell us about man in the 21st century? Can we talk of post-humanism? These are some of the basic questions this paper wishes to address in relation to the symposium’s theme Architecture and Urban Space. [less ▲]

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See detailPirates informatiques et mathématique modulaire
Rigo, Michel ULg

Learning material (2007)

De nos jours, l'envoi de messages secrets requiert la manipulation de nombres ayant plus de cent chiffres décimaux. Nous illustrons une technique cryptographique standard (le RSA) dont la sécurité réside ... [more ▼]

De nos jours, l'envoi de messages secrets requiert la manipulation de nombres ayant plus de cent chiffres décimaux. Nous illustrons une technique cryptographique standard (le RSA) dont la sécurité réside dans le fait qu'il est "rapide", sur le plus banal des ordinateurs personnels, de calculer le produit de deux "grands" nombres (cela se compte au pire en secondes), alors que le temps nécessaire pour effectuer l'opération inverse de factorisation prend, dans l'état actuel des connaissances mathématiques, énormément plus de temps (que l'on pourrait estimer en milliards d'années même pour un super-calculateur !). [less ▲]

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See detailLe pire ami de l'homme. Du lapin de garenne aux guerres biologiques
Mougenot, Catherine ULg; Strivay, Lucienne ULg

Book published by La Découverte (2011)

Mais pourquoi donc écrire une histoire des lapins ? Longtemps on a considéré que l'Histoire relevait des seuls humains : on voulait croire que la « nature » restait extérieure et indifférente à nos ... [more ▼]

Mais pourquoi donc écrire une histoire des lapins ? Longtemps on a considéré que l'Histoire relevait des seuls humains : on voulait croire que la « nature » restait extérieure et indifférente à nos affaires. Mais nous découvrons peu à peu, grâce à l'écologie, que nos vies sont depuis longtemps imbriquées à celles des animaux et qu'elles seraient impossibles sans eux. Tant qu'on les considère comme des matériaux indifférents, façonnables à notre gré, on s'expose à de sérieux retours de flamme. Les lapins en sont un exemple fameux : ils ne font jamais ce qu'on attend d'eux. Ils sont récalcitrants, rebelles, résistants... Dans ce livre qui propose une nouvelle manière de faire de l'histoire avec les animaux, les auteures sont engagées dans une folle course-poursuite avec des lapins qui toujours inventent, changent les règles du jeu, colonisent, se retirent... Ils sont toujours actifs, là où on aurait juré qu'ils seraient passivement soumis à nos projets et ambitions. Les auteures elles-mêmes ont été prises au piège ! Et s'il fallait en passer par les lapins pour mieux comprendre les humains ? Et si, mieux qu'une histoire des lapins, il s'agissait de commencer à écrire du point de vue des lapins ? Si on ne peut plus penser les humains sans les animaux, alors l'histoire, la sociologie, la philosophie doivent apprendre à bien les traiter... [less ▲]

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See detailPirlindole and dehydropirlindole protect rat cultured neuronal cells against oxidative stress-induced cell death through a mechanism unrelated to MAO-A inhibition
Boland, André ULg; Gerardy, J.; Breeur, Danielle ULg et al

in British Journal of Pharmacology (2002), 135(3), 713-720

1 It has been shown that the MAO (monoamine oxidase)-B inhibitor deprenyl (DPR, selegiline) protects some cell types against oxidative stress. By decreasing H2O2 production, MAO-A inhibitors could also ... [more ▼]

1 It has been shown that the MAO (monoamine oxidase)-B inhibitor deprenyl (DPR, selegiline) protects some cell types against oxidative stress. By decreasing H2O2 production, MAO-A inhibitors could also reduce oxidative stress. 2 This study reports the effect of the MAO-A inhibitors, pirlindole (PIR), dehydropirlindole (DHP), brofaromine (BRO) and moclobemide (MCL) on primary-cultured brain cells exposed to iron-mediated toxicity. A comparison with trolox (TRO), a hydrosoluble vitamin-E analogue that protects against such an induced stress, was performed. 3 Rat hippocampal or cortical cultured cells were exposed either to 2 mum FeSO4 alone or in the presence of PIR, DHP, BRO, DPR, MCL or TRO. Cell survival (lactate-dehydrogenase measurements, 16 h incubation), intracellular peroxide production (DCF-fluorescence. I h incubation), lipoperoxidation (TBARS-fluorescence, 6 h incubation) and mitochondrial function (MTT-test, 16 h incubation) were assessed. 4 PIR, DHP and TRO significantly protected cultures (P<0.05) against Fe2+-induced toxicity in a concentration-dependent manner. The EC50s of these compounds were 6, 12 and 19 muM, respectively, in hippocampal cells. For cortical cell cultures incubated in the presence of iron and PIR or DHP, EC50s were 5 and 6 muM respectively. All Hill coefficients were close to unity. BRO, MCL and DPR were not protective in any type of culture. The IC50s for the inhibition of MAO-A were 2, 2 and 0.2 muM for PIR, DHP and BRO, respectively. PIR, DHP and TRO, but not DPR, induced a significant decrease in both intracellular peroxide production and lipoperoxidation. They also improved mitochondrial function. 5 These experiments show that PIR and DHP can protect hippocampal and cortical neurons against oxidative stress at pharmacologically relevant concentrations. This protective effect seems unrelated to inhibition of MAO-A, but possibly involves free radical scavenging. [less ▲]

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See detailPirlindole: a selective reversible inhibitor of monoamine oxidase A. A review of its preclinical properties.
Bruhwyler, J.; Liégeois, Jean-François ULg; Geczy, J.

in Pharmacological Research (1997), 36(1), 23-33

Pirlindole is a tetracyclic compound that has been characterized as a potential antidepressant drug. It has pharmacological characteristics in common with both tricyclic antidepressants and classical ... [more ▼]

Pirlindole is a tetracyclic compound that has been characterized as a potential antidepressant drug. It has pharmacological characteristics in common with both tricyclic antidepressants and classical irreversible monoamine oxidase inhibitors. Its main mechanism of action consists of a selective and reversible inhibition of monoamine oxidase A. Secondarily, it exerts an inhibitory effect on noradrenaline and 5-hydroxytryptamine reuptakes. It has no effect on the dopaminergic and cholinergic systems. It has only a low potential for amplifying tyramine and noradrenaline pressor effect, which makes one expect that it will not be at the basis of a 'cheese effect'. Pirlindole has an absolute bioavailability of between 20 and 30% due to an extensive first-pass effect. Orally, the Tmax varies between 2.5 and 6 h in the rat and 0.8 and 2 h in the dog. Two phases of elimination (7.5 and 34-70 h) are measured in the rat and three phases in the dog (1.3, 10.8 and 185 h); it is extensively metabolized. The rat eliminates mainly unconjugated products while the dog eliminates mostly conjugated products. Acute and chronic toxicological studies have not revealed potentially dangerous effects of the drug at the usual doses. It does not present measurable mutagenic, clastogenic or carcinogenic properties. Thus, pirlindole shows pharmacological, pharmacokinetic and toxicological properties which make it suitable for the management of depression. [less ▲]

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See detailLa piroplasmose: une réalité belge ?
Mantran, A; Votion, Dominique ULg; Amory, Hélène ULg

in Proceedings of the 21th Annual Congress of the Belgian Equine Practitioners Society (BEPS) (2004)

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See detailPiroxicam fails to reduce myocellular enzyme leakage and delayed onset muscle soreness induced by isokinetic eccentric exercise
Croisier, Jean-Louis ULg; Camus, Gérard; Deby-Dupont, G. et al

in Pflügers Archiv : European Journal of Physiology (1996), 431

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See detailPiroxicam fails to reduce myocellular enzyme leakage and delayed onset muscle soreness induced by isokinetic eccentric exercise.
Croisier, Jean-Louis ULg; Camus, G.; Monfils, T. et al

in Mediators of Inflammation (1996), 5(3), 230-4

To test the hypothesis that delayed onset muscular soreness (DOMS) following intense eccentric muscle contraction could be due to increased production of prostaglandin E(2) (PGE(2)), ten healthy male ... [more ▼]

To test the hypothesis that delayed onset muscular soreness (DOMS) following intense eccentric muscle contraction could be due to increased production of prostaglandin E(2) (PGE(2)), ten healthy male subjects were studied. Using a double-blind randomized crossover design, each subject performed two isokinetic tests separated by a period of at least 6 weeks: once with placebo, and once with piroxicam (Feldene((R))). They were given one capsule containing either placebo or piroxicam (20 mg) per day for 6 days with initial doses given starting 3 days prior to isokinetic testing. Exercise consisted of eight stages of five maximal contractions of the knee extensor and flexor muscle groups of both legs separated by 1 min rest phases, on a Kin Trex device at 60( degrees )/s angular velocity. The subjective presence and intensity of DOMS were evaluated using a visual analogue scale immediately after, and 24 and 48 h after each test. The mean plasma concentration of PGE(2) measured at rest and after exercise was significantly lower in the group treated with piroxicam (p < 0.05). However, statistical analysis (two-way ANOVA test) revealed that exercise did not cause any significant change of mean plasma PGE(2) over time in either of the two groups. Eccentric work was followed by severe muscle pain in extensor and flexor muscle groups. Maximal soreness was noted 48 h postexercise. Serum creatine kinase activity and the serum concentration of myoglobin increased significantly, and reached peak values 48 h after exercise in both experimental conditions (p < 0.001). By paired t-test, it appeared that there were no significant differences in the serum levels of these two markers of muscle damage between the two groups at any time point. We conclude that: (1) oral administration of piroxicam fails to reduce muscle damage and DOMS caused by strenuous eccentric exercise; and (2) the hypothetical role of increased PGE(2) production in eccentric exercise-induced muscle damage, DOMS, and reduced isokinetic performance is not substantiated by the present results. [less ▲]

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See detailPiroxicam-Beta-Cyclodextrin in the Treatment of Acute Pain of Rheumatic Disease
Reginster, Jean-Yves ULg; Franchimont, P.

in European Journal of Rheumatology and Inflammation (1993), 12(4), 38-46

Analgesics continue to be the mainstay of therapy in osteoarthritis. Non-steroidal anti-inflammatory drugs (NSAIDs) play an important role, particularly where there is a significant inflammatory component ... [more ▼]

Analgesics continue to be the mainstay of therapy in osteoarthritis. Non-steroidal anti-inflammatory drugs (NSAIDs) play an important role, particularly where there is a significant inflammatory component to the osteoarthritis. Piroxicam-beta-cyclodextrin (PBC) is a new formulation in which piroxicam has been complexed with beta-cyclodextrin, a cyclic oligosaccharide. This results in an increase in the rate of absorption of the active compound and, consequently, in an earlier onset of analgesic action. PBC, like piroxicam, is administered once daily. PBC has been used in the treatment of osteoarthritis. In comparison with piroxicam, PBC showed a more rapid analgesic-anti-inflammatory action after the first administration in patients with active osteoarthritis. Subsequent evaluations at the second, fifth and last day of treatment demonstrated a comparable efficacy of the two drugs. The efficacy and tolerability of PBC was compared with other NSAIDs given intramuscularly, such as diclofenac and ketoprofen. The three compounds provided marked pain relief within thirty minutes and this increased progressively until the third to fourth hour. The efficacy of oral PBC was comparable to that of intramuscular diclofenac or ketoprofen. In comparison with metamisole PBC achieved a more rapid and sustained reduction in pain intensity during the first twelve hours of treatment. This rapid and marked reduction in pain intensity with PBC was also observed in patients with low-back pain when compared with etodolac. In view of its efficacy, tolerability and rapid onset of action, piroxicam-beta-cyclodextrin appears to be an useful analgesic and a prominent progress in the treatment of acute rheumatic pain. [less ▲]

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See detailPISA 2000 : lire ou ne pas lire : état de la question
Lafontaine, Dominique ULg; Vanhulle, Sabine

Report (2002)

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