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See detailInteractions between acetylcholine and substance P effects on lung mechanics in the rabbit.
Delaunois, Annie ULg; Gustin, Pascal ULg; Segura, P. et al

in Fundamental & Clinical Pharmacology (1996), 10(3), 278-88

The pharmacological mechanisms involved in the acetylcholine (ACh)- and substance P (SP)-induced changes in pulmonary mechanics were studied in isolated perfused rabbit lungs. Tracheal pressure (Ptr) and ... [more ▼]

The pharmacological mechanisms involved in the acetylcholine (ACh)- and substance P (SP)-induced changes in pulmonary mechanics were studied in isolated perfused rabbit lungs. Tracheal pressure (Ptr) and airflow were measured by a Fleisch pneumotachograph and pressure transducers. Air volume, lung resistance (RL) and dynamic compliance (Cdyn) were calculated. ACh induced a dose-dependent increase in Ptr and RL, and a decrease in Cdyn. These effects were strongly prevented by atropine, and partly by SR140333, a neurokinin NK1 receptor antagonist; SR48968, a neurokinin NK2 receptor antagonist; indomethacin and antihistaminics. Ketanserin had no significant protective effect against ACh. SP also induced concentration-dependent increases in RL and decreases in Cdyn. SR140333 and atropine strongly inhibited the effects of SP, while ketanserin, SR48968, antihistaminics and indomethacin did not protect the lungs against this drug. 5-hydroxytryptamine induced no significant change in lung mechanic parameters. Cumulative concentrations of histamine increased RL and decreased Cdyn. We conclude that ACh-induced changes in lung resistance and compliance are in part mediated by a direct effect on airway smooth muscle and in part by the stimulation of C fibers, by the release of histamine from mast cells and by the synthesis of arachidonic acid metabolites. In turn, the effects of SP on lung mechanics are partly due to cholinergic activation. [less ▲]

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See detailInteractions between Active-Site Serine Beta-Lactamases and So-Called Beta-Lactamase-Stable Antibiotics. Kinetic and Molecular Modelling Studies
Matagne, André ULg; Lamotte-Brasseur, J.; Frère, Jean-Marie ULg

in European Journal of Biochemistry (1993), 217(1), 61-67

The interactions between imipenem and four monobactams and three class A beta-lactamases have been studied in detail. Despite their reputation as being beta-lactamase-stable, some of these compounds were ... [more ▼]

The interactions between imipenem and four monobactams and three class A beta-lactamases have been studied in detail. Despite their reputation as being beta-lactamase-stable, some of these compounds were significantly hydrolysed by the enzymes. The results obtained with the Streptomyces albus G beta-lactamase have been analysed in the light of molecular modelling studies. The discussion is extended to include other so-called beta-lactamase-stable antibiotics to demonstrate that this appellation can often be misleading. [less ▲]

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See detailInteractions between Active-Site-Serine Beta-Lactamases and Compounds Bearing a Methoxy Side Chain on the Alpha-Face of the Beta-Lactam Ring: Kinetic and Molecular Modelling Studies
Matagne, André ULg; Lamotte-Brasseur, J.; Dive, Georges ULg et al

in Biochemical Journal (1993), 293((Pt 3)), 607-611

The interactions between three class A beta-lactamases and compounds bearing a methoxy side chain on the alpha-face of the beta-lactam ring (cefoxitin, moxalactam and temocillin) have been studied. When ... [more ▼]

The interactions between three class A beta-lactamases and compounds bearing a methoxy side chain on the alpha-face of the beta-lactam ring (cefoxitin, moxalactam and temocillin) have been studied. When compared with the situation prevailing with good substrates, both acylation and deacylation steps appeared to be severely impaired. Molecular modelling studies of the structures of the Henri-Michaelis complexes and of the acyl-enzymes indicate a major displacement of the crystallographically observed water molecule which connects the glutamate-166 and serine-70 side chains and underline the role of this water molecule in both reaction steps. [less ▲]

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See detailInteractions between Active-Site-Serine Beta-Lactamases and Mechanism-Based Inactivators: A Kinetic Study and an Overview
Matagne, André ULg; Ghuysen, M. F.; Frère, Jean-Marie ULg

in Biochemical Journal (1993), 295((Pt 3)), 705-711

The interactions between three class A beta-lactamases and three beta-lactamase inactivators (clavulanic acid, sulbactam and olivanic acid MM13902) were studied. Interestingly, the interaction between the ... [more ▼]

The interactions between three class A beta-lactamases and three beta-lactamase inactivators (clavulanic acid, sulbactam and olivanic acid MM13902) were studied. Interestingly, the interaction between the Streptomyces cacaoi beta-lactamase and clavulanate indicated little irreversible inactivation. With sulbactam, irreversible inactivation was found to occur with the three studied enzymes, but no evidence for transiently inactivated adducts was found. Irreversible inactivation of the S. albus G and S. cacaoi enzymes was particularly slow. With olivanate, irreversible inactivation was also observed with the three enzymes, but with the S. cacaoi enzyme, no hydrolysis could be detected. A tentative summary of the results found in the literature is also presented (including 6 beta-halogenopenicillanates), and the general conclusions underline the diversity of the mechanisms and the wide variations of the rate constants observed when class A beta-lactamases interact with beta-lactamase inactivators, in agreement with the behaviours of the same enzymes towards their good and poor substrates. [less ▲]

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See detailInteractions between aromatase (estrogen synthase) and dopamine in the control of male sexual behavior in quail
Balthazart, Jacques ULg; Baillien, M.; Ball, G. F.

in Comparative Biochemistry & Physiology Part B (2002), 132(1), 37-55

In male quail, like in other vertebrates including rodents, testosterone acting especially through its estrogenic metabolites is necessary for the activation of male sexual behavior. Also, the ... [more ▼]

In male quail, like in other vertebrates including rodents, testosterone acting especially through its estrogenic metabolites is necessary for the activation of male sexual behavior. Also, the administration of dopamine agonists and antagonists profoundly influences male sexual behavior. How the steroid-sensitive neural network and dopamine interact physiologically, remains largely unknown. It is often implicitly assumed that testosterone or its metabolite estradiol, stimulates male sexual behavior via the modification of dopaminergic transmission. We have now identified in quail two possible ways in which dopamine could potentially affect sexual behavior by modulating the aromatization of testosterone into an estrogen. One is a long-acting mechanism that presumably involves the modification of dopaminergic transmission followed by the alteration of the genomic expression of aromatase. The other is a more rapid mechanism that does not appear to be dopamine receptor-mediated and may involve a direct interaction of dopamine with aromatase (possibly via substrate competition). We review here the experimental data supporting the existence of these controls of aromatase activity by dopamine and discuss the possible contribution of these controls to the activation of male sexual behavior. (C) 2002 Elsevier Science Inc. All rights reserved. [less ▲]

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See detailInteractions between bacterial surfaces and milk proteins, impact on food emulsions stability
Ly, M. H.; Aguedo, Mario ULg; Goudot, S. et al

in Food Hydrocolloids (2008), 22(5), 742-751

Bacteria possess physicochemical surface properties such as hydrophobicity, Lewis acid/base and charge which are involved in physicochemical interactions between cells and interfaces. Moreover, food ... [more ▼]

Bacteria possess physicochemical surface properties such as hydrophobicity, Lewis acid/base and charge which are involved in physicochemical interactions between cells and interfaces. Moreover, food matrices are complex and heterogeneous media, with a microstructure depending on interactions between the components in media (van der Waals, electrostatic or structural forces, etc.). Despite the presence of bacteria in fermented products, few works have investigated how bacteria interact with other food components. The objective of the present study was to determine the effects of the surface properties of lactic acid bacteria on the stability of model food emulsions. The bacteria were added to oil/water emulsions stabilized by milk proteins (sodium caseinate, whey proteins concentrate or whey proteins isolate) at different pH (from 3 to 7.5). The effect of bacteria on the emulsions stability depended on the surface properties of strains and also on the characteristics of emulsions. Flocculation and aggregation phenomena were observed in emulsion at pHs for which the bacterial surface charge was opposed to the one of the proteins. The effects of bacteria on the stability of emulsion depended also on the concentration of cations present in media such as Ca2+. These results show that the bacteria through their surface properties could interact with other compounds in matrices, consequently affecting the stability of emulsions. The knowledge and choice of bacteria depending on their surface properties could be one of the important factors to control the stability of matrices such as fermentation media or fermented products. © 2007 Elsevier Ltd. All rights reserved. [less ▲]

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See detailInteractions between beta-lactam antibiotics and isolated membranes of Streptococcus faecalis ATCC 9790
Coyette, Jacques; Ghuysen, Jean-Marie ULg; Binot, Françoise ULg et al

in European Journal of Biochemistry (1977), 75(1), 231-239

The DD-carboxypeptidase-exchange membrane-bound enzyme in Streptococcus faecalis ATCC 9790 reacts with beta-lactam antibiotics to form complexes with rather long half-lives. Depending upon the antibiotic ... [more ▼]

The DD-carboxypeptidase-exchange membrane-bound enzyme in Streptococcus faecalis ATCC 9790 reacts with beta-lactam antibiotics to form complexes with rather long half-lives. Depending upon the antibiotic, the second-order rate constants for complex formation range from 0.75-560 M-1 S-1 (at 37 degrees C and in water) and the first-order rate constants for complex breakdown range from 1.3 to 26 x 10(-5) s-1 (at 37 degrees C and in 5 mM phosphate buffer pH 7.5). There are about 30 pmol of DD-carboxypeptidase-exchange enzyme per mg of membrane protein. The degradation products arising from benzylpenicillin are phenylacetylglycine and probably N-formyl-D-penicillamine. Isolated membranes also contain other penicillin binding sites (about 70 pmol/mg membrane protein). That part of benzylpenicillin which reacts with at least some of these latter sites is slowly degraded into penicilloic acid. Normal functioning of the DD-carboxypeptidase-exchange membrane-bound enzyme is important, if not essential, for cell growth. With the beta-lactam antibiotics tested inhibition of cell growth is mainly related to the rates of formation of the inactive enzyme-antibiotic complexes. The relationship, however, is not a direct one probably due to the competitive effect exerted by the other penicillin binding sites. [less ▲]

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See detailInteractions between CRF and acetylcholine in the modulation of cognitive behaviour.
Warnock, Geoffrey ULg; Prickaerts, Jos; Steckler, Thomas

in Levin, E. D. (Ed.) Neurotransmitter Interactions and Cognitive Function (2006)

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See detailInteractions between cytochrome P-450 activities and ozone-induced modulatory effects on endothelial permeability in rabbit lungs: influence of gender.
Delaunois, Annie ULg; Florquin, Sandra ULg; Segura, P. et al

in Inhalation Toxicology (1999), 11(11), 999-1014

The effects of rabbit exposure to ozone (O(3)) (0.4 ppm for 4 h) on two different cytochrome P-450 (CYP450)-dependent activities were investigated. In turn, the role of CYP450 in the inhibitory effect of ... [more ▼]

The effects of rabbit exposure to ozone (O(3)) (0.4 ppm for 4 h) on two different cytochrome P-450 (CYP450)-dependent activities were investigated. In turn, the role of CYP450 in the inhibitory effect of O(3) on acetylcholine (ACh)-evoked increase in endothelial permeability was also assessed. Immediately after the period of exposure, rabbits of both sexes were sacrificed and their lungs were extracted. Some lungs were used for preparation of microsomes and measurement of 7-ethoxyresorufin O-deethylase (EROD) and parathion oxidase activities. Other rabbit lungs were isolated and recirculatingly blood-free perfused. Arterial, venous pressures, and lung weight were continuously recorded. Capillary pressure was measured by applying the double occlusion method. Capillary filtration coefficient (K(f,c)) was evaluated by measuring the amount of fluid filtering through the endothelium when vascular pressures were suddenly increased. Dose-response curves to ACh were constructed in air- or O(3)-exposed rabbits. Some animals were pretreated with piperonyl butoxide (PBO), a well-known inhibitor of CYP450. O(3) significantly reduced both EROD and parathion oxidase lung microsomal activities in females, while it had no effect in males. Exposure to O(3) strongly inhibited the ACh-induced increase in K(f,c). Pretreatment with PBO reversed the modulatory effect of O(3) on endothelial permeability in male rabbits, but not in females. It was concluded (1) that inhibition of 2 different CYP450-dependent activities after exposure to 0.4 ppm O(3) for 4 h appears to be a gender-dependent phenomenon, and (2) that CYP450 is probably involved in the O(3)-evoked inhibitory mechanism against ACh-induced increase in endothelial permeability, but only in males. [less ▲]

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See detailInteractions between endothelial cells and smooth muscle cells after their activation by hypoxia. A possible etiology for venous disease.
Michiels, C.; Arnould, T.; Janssens, D. et al

in International Angiology : A Journal of the International Union of Angiology (1996), 15(5), 124-130

Because of their localization at the interface between blood and tissue, endothelial cells are responsible for the maintenance of vascular homeostasis. They fulfil a series of various functions and ... [more ▼]

Because of their localization at the interface between blood and tissue, endothelial cells are responsible for the maintenance of vascular homeostasis. They fulfil a series of various functions and constantly interact with circulating leukocytes and with the smooth muscle cells (SMC) present in the media. Any disturbance of their metabolism can thus lead to alterations of the blood vessel functions. We have shown that hypoxia, for example resulting from venous stasis, induces the activation of endothelial cells which then release inflammatory mediators able to activate neutrophils and to induce their infiltration as well as growth factors for SMC. We propose that these processes are the beginning of a cascade of events eventually leading to structural and functional modifications of the venous wall similar to the ones observed in varicose vein wall. The endothelium alterations resulting from venous stasis would thus be the origin of the development of the venous disease. Pharmacological and clinical evidence reinforce this hypothesis. [less ▲]

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See detailInteractions between fibroblasts and a reconstituted basement membrane matrix
Emonard, H.; Calle, A.; Grimaud, J. A. et al

in Journal of Investigative Dermatology (1987), 89

A gel-like reconstituted basement membrane matrix containing type IV collagen, laminin, entactin, nidogen, and heparan sulfate proteoglycan was used to examine the interactions between normal calf skin ... [more ▼]

A gel-like reconstituted basement membrane matrix containing type IV collagen, laminin, entactin, nidogen, and heparan sulfate proteoglycan was used to examine the interactions between normal calf skin fibroblasts and basement membranes. Within 6 h after seeding, fibroblasts initiated a migration that resulted in the formation of a cellular network after 1 day of culture on top of the gel. Electron microscopy revealed that fibroblasts were able to remodel the basement membrane matrix by penetrating into the gel (from day 3), depositing fibronectin and collagen fibers, and retracting this extracellular matrix. Fibroblasts cultured on the Engelbreth-Holm-Swarm reconstituted basement membrane matrix displayed ultrastructural features characterized by a poor synthetic apparatus (rough endoplasmic reticulum and Golgi vesicles), a large cytoskeleton, and intracytoplasmic vesicles containing laminin. Thus the reconstituted basement membrane matrix is remodeled by skin fibroblasts, and reciprocally their ultrastructural morphologic features are affected by this matrix. [less ▲]

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See detailInteractions between follicular dendritic cells and lymphoid cells.
Heinen, Ernst ULg; Braun, M.; Louis, Edouard ULg et al

in Advances in Experimental Medicine and Biology (1988), 237

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See detailInteractions between gellan gum and other polysaccharides.
Blecker, Christophe ULg; Razafindralambo, Hary ULg; Paquot, Michel ULg

in Czech Journal of Food Sciences [=CJFS] (2000), 18

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See detailInteractions Between Heavy Metals and Nitrogen and Their Ecological Effects.
Zu, Yanqun; Li, Yuan; Bock, Laurent ULg et al

in Journal of Agro-Environment Science (2008), 27(1), 7-17

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See detailInteractions between IL-1bêta, IL-6, IL-8 and LIF produced by human chondrocytes
Henrotin; Franchimont, P; Reginster, Jean-Yves ULg

in The Official EULAR Journal for Education and Information (1995), 24

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See detailInteractions between IL-Ibêta, IL-6, IL-8, and LIF produced by human articular chondrocytes
Henrotin; Reginster, Jean-Yves ULg; Franchimont, P

in Osteoarthritis and Cartilage (1994), 2(S1), 52

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See detailInteractions between kinases and phosphatases in the rapid control of brain aromatase
Balthazart, Jacques ULg; Baillien, M.; Ball, G. F.

in Journal of Neuroendocrinology (2005), 17(9), 553-559

Aromatization of testosterone into oestradiol plays a key role in the activation of male sexual behaviour in many vertebrate species. Rapid changes in brain aromatase activity have recently been ... [more ▼]

Aromatization of testosterone into oestradiol plays a key role in the activation of male sexual behaviour in many vertebrate species. Rapid changes in brain aromatase activity have recently been identified and the resulting changes in local oestrogen bioavailability could modulate fast behavioural responses to oestrogens. In quail hypothalamic homogenates, aromatase activity is down-regulated within minutes by calcium-dependent phosphorylations in the presence of ATP, MgCl2 and CaCl2 (ATP/Mg/Ca). Three kinases (protein kinases A and C and calmodulin kinase; PKA, PKC and CAMK) are potentially implicated in this process. If kinases decrease aromatase activity in a reversible manner, then it would be expected that the enzymatic activity would increase and/or return to baseline levels in the presence of phosphatases. We showed previously that 0.1 mM vanadate (a general inhibitor of protein phosphatases) significantly decreases aromatase activity but specific protein phosphatases that could up-regulate aromatase activity have not been identified to date. The reversibility of aromatase activity inhibition by phosphorylations was investigated in the present study using alkaline and acid phosphatase (Alk and Ac PPase). Unexpectedly, Alk PPase inhibited aromatase activity in a dose-dependent manner in the presence, as well as in the absence, of ATP/Mg/Ca. By contrast, Ac PPase completely blocked the inhibitory effects of ATP/Mg/Ca on aromatase activity, even if it moderately inhibited aromatase activity in the absence of ATP/Mg/Ca. However, the addition of Ac PPase was unable to restore aromatase activity after it had been inhibited by exposure to ATP/Mg/Ca. Taken together, these data suggest that, amongst the 15 potential consensus phosphorylation sites identified on the quail aromatase sequence, some must be constitutively phosphorylated for the enzyme to be active whereas phosphorylation of the others is involved in the rapid inhibition of aromatase activity by the competitive effects of protein kinases and phosphatases. Two out of these 15 putative phosphorylation sites occur in an environment corresponding to the consensus sites for PKC, PKA (and possibly a CAMK) and, in all probability, represent the sites whose phosphorylation rapidly blocks enzyme activity. [less ▲]

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See detailInteractions between new phenolic glycolipids and model membrane
Sainvitu, Pauline ULg; Nasir, Mehmet Nail ULg; Crowet, Jean-Marc ULg et al

Poster (2014, February 07)

Model membrane based on phospholipids (PL) layers are useful to mimic properties of plasma membranes. The interactions between new synthesized phenolic glycolipids (PGL) and biological membrane are ... [more ▼]

Model membrane based on phospholipids (PL) layers are useful to mimic properties of plasma membranes. The interactions between new synthesized phenolic glycolipids (PGL) and biological membrane are crucial to determine their potential as drug candidates and their cytotoxicity . [less ▲]

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See detailInteractions between non-classical β-lactam compounds and the β-lactamases of Actinomadura R39 and Streptomyces albus G
Kelly, Judith; Frère, Jean-Marie ULg; Duez, Colette ULg et al

in Biochemical Journal (1981), 199

Streptomyces albus G secretes a Zn2+-containing D-alanyl-D-alanine peptidase. Streptomyces R61 and Actinomadura R39 secrete D-alanyl-D-alanine-cleaving serine peptidases. The effect of non-classical beta ... [more ▼]

Streptomyces albus G secretes a Zn2+-containing D-alanyl-D-alanine peptidase. Streptomyces R61 and Actinomadura R39 secrete D-alanyl-D-alanine-cleaving serine peptidases. The effect of non-classical beta-lactam antibiotics on these three model enzymes has been studied. Mecillinam, cefoxitin, quinacillin, quinacillin sulphone, clavulanate and N-formimidoylthienamycin have no effect on the Zn2+-containing enzyme. 6-Amino-penicillanic acid slowly inactivates this enzyme and 7-aminocephalosporanic acid behaves as a reversible inhibitor. Cefoxitin and N-formimidoylthienamycin are potent anti-bacterial agents; they effectively inactivate the serine R39 enzyme and, to a lesser extent, the serine R61 enzyme. All the other beta-lactam compounds tested, including mecillinam, are slow inactivators of these serine enzymes. The intermediates formed between 6-aminopenicillanic acid and the R61 and R39 enzymes are long- and short-lived respectively, whereas those formed between 7-aminocephalosporanic acid and the same R61 and R39 enzymes are short- and long-lived respectively. Breakdown of the short-lived intermediates thus obtained gives rise to several ninhydrin-positive degradation products. The intermediates formed between clavulanate and the serine enzymes are long-lived. With the R39 enzyme, the inactivated complex formed in a first step undergoes subsequent monomolecular rearrangement to give rise to a second species exhibiting a high absorbance at 273 nm. [less ▲]

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