References of "Hoebeke, Maryse"
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See detailEffects of sphingosine and sphingosine analogues on the free radical production by stimulated neutrophils: ESR and chemiluminescence studies.
Mouithys-Mickalad, Ange ULg; Deby, Ginette ULg; Hoebeke, Maryse ULg et al

in Mediators of Inflammation (1997), 6(5-6), 327-33

Sphingolipids inhibit the activation of the neutrophil (PMN) NADPH oxidase by protein kinase C pathway. By electron spin resonance spectroscopy (ESR) and chemiluminescence (CL), we studied the effects of ... [more ▼]

Sphingolipids inhibit the activation of the neutrophil (PMN) NADPH oxidase by protein kinase C pathway. By electron spin resonance spectroscopy (ESR) and chemiluminescence (CL), we studied the effects of sphingosine (SPN) and ceramide analogues on phorbol 12-myristate 13-acetate (PMA, 5 x 10(-7)M) stimulated PMN (6 x 10(6) cells). By ESR with spin trapping (100 mM DMPO: 5,5-dimethyl-1-pyrroline-Noxide), we showed that SPN (5 to 8 x 10(-6)M), C(2)-ceramide (N-acetyl SPN) and C(6)-ceramide (N-hexanoyl SPN) at the final concentration of 2 x 10(-5) and 2 x 10(-4)M inhibit the production of free radicals by stimulated PMN. The ESR spectrum of stimulated PMN was that of DMPO-superoxide anion spin adduct. Inhibition by 5 x 10(-6)M SPN was equivalent to that of 30 U/ml SOD. SPN (5 to 8 x 10(-6)M) has no effect on in vitro systems generating superoxide anion (xanthine 50 mM/xanthine oxidase 110 mU/ml) or hydroxyl radical (Fenton reaction: 88 mM H(2)O(2), 0.01 mM Fe(2+) and 0.01 mM EDTA). SPN and N-acetyl SPN also inhibited the CL of PMA stimulated PMN in a dose dependent manner (from 2 x 10(-6) to 10(-5)M), but N-hexanoyl SPN was less active (from 2 x 10(-5) to 2 x 10(-4)M). These effects were compared with those of known PMN inhibitors, superoxide dismutase, catalase and azide. SPN was a better inhibitor compared with these agents. The complete inhibition by SPN of ESR signal and CL of stimulated PMN confirms that this compound or one of its metabolites act at the level of NADPH-oxidase, the key enzyme responsible for production of oxygen-derived free radicals. [less ▲]

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See detailPhotosensitized generation of hydroxyl radical by eught new sulfur and selenium analogs of psoralen
Collet, A.; Hoebeke, Maryse ULg; Piette, J. et al

in Journal of Photochemistry and Photobiology B : Biology (1996), 35

comparative study by ESR of the hydroxyl radical generation by 8 eight new sulfur and selenium analogs of psoralen

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See detailBacteriochlorin a activated oxygen forms production: a ESR and a laser flash photolysis study
Hoebeke, Maryse ULg; Lindqvist, L.; van de Vorst, A.

Conference (1996)

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See detailThe importance of liposomes as models and tools in the understanding of photosensitization mechanisms
Hoebeke, Maryse ULg

in Journal of Photochemistry and Photobiology B : Biology (1995), 28(3), 189-196

The various applications of liposomes in understanding photosensitization are described in this paper, with particular emphasis on the various kinds of information that these models allow to obtain in ... [more ▼]

The various applications of liposomes in understanding photosensitization are described in this paper, with particular emphasis on the various kinds of information that these models allow to obtain in phototherapy. Liposomes are simple vesicles in which an aqueous phase is enclosed by a phospholipidic membrane. They are suitable models mimicking specific situations occurring <br />m vivo and they allow study of the influence of physieochemieal, photobioiogieal and biochemical factors on the uptake of photosensitizers by tissues, their mechanisms of action and the subsequent photoinduced tumor necrosis. Moreover, solubilization of the sensitizer into the bilayer seems to improve its tumoral selectivity and its photodynamic efficiency. [less ▲]

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See detailOn the charge transfer pathway in the Merocyanine 540 triplet state quenching by nitroxyl radical
Hoebeke, Maryse ULg; Van de Vorst, A.

in Photochemistry & Photobiology (1995), 61

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See detailQuenching of Merocyanine 540 Triplet State by Nitroxyl Radicals in Liposomal Systems: A Laser Flash Photolysis Study
Hoebeke, Maryse ULg; Enescu, M.; Lindqvist, L.

in Journal of Photochemistry and Photobiology B : Biology (1994), 22(3), 229-33

Laser flash photolysis experiments were undertaken to investigate the interaction between stearic acid nitroxide spin probes and photoexcited merocyanine 540 (MC540) in dimyristoyl-L-alpha ... [more ▼]

Laser flash photolysis experiments were undertaken to investigate the interaction between stearic acid nitroxide spin probes and photoexcited merocyanine 540 (MC540) in dimyristoyl-L-alpha-phosphatidylcholine liposomes (membrane model). The measurements of the paramagnetic signal decay kinetics of four different spin-labelled stearic acids (n-DSA) show that the direct interaction between the dye and the probe is affected by the position of the nitroxyl group along the carbon chain. Laser flash photolysis results reveal a significant decrease in the MC540 triplet lifetime in the presence of n-DSA, the effect depending on the depth at which the nitroxyl moiety is localized in the bilayer. Previous results on the rate of disappearance of the electron spin resonance (ESR) nitroxide signal on continuous photolysis of the same systems do not show the same dependence on the localization of the nitroxyl moiety in the liposome. Although the MC540 triplet state seems to be implicated in the reaction process, the results suggest that ESR and laser flash experiments demonstrate two different kinds of mechanism. [less ▲]

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See detailVariations of lyoluminescence with commercial origin of the dosimeters
Galand, Eric; Niezette, Jacques; Vanderschuren, Jacques et al

in Radiation Physics and Chemistry (1994), 43

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See detailDestruction of Stearic Acid Nitroxyl Radicals Mediated by Photoexcited Merocyanine 540 in Liposomal and Micellar Systems
Hoebeke, Maryse ULg; Seret, Alain ULg; Piette, Jacques ULg et al

in Biochemistry (1993), 32(10), 2730-2736

Fatty acid spin labels have been included into liposomes and micelles, in order to study the photochemical behavior of merocyanine 540 toward nitroxyl radicals situated at various depths in the bilayer or ... [more ▼]

Fatty acid spin labels have been included into liposomes and micelles, in order to study the photochemical behavior of merocyanine 540 toward nitroxyl radicals situated at various depths in the bilayer or the surfactant layer. Visible illumination of the dye, either free in ethanol or bound to liposomes or micelles, leads to the reduction of the electron spin resonance signal of the label. The efficiency of the interaction between merocyanine 540 and spin labels depends on the depth at which the nitroxyl moiety is localized in the micelle or vesicle. Fluorescence measurements indicate that the first excited singlet state of merocyanine 540 is not directly implicated in the reaction mechanism. Flash photolysis experiments conducted in aqueous solutions of hexadecyltrimethylammonium bromide micelles show that the presence of nitroxyl radical decreases the rate constant of triplet decay in a concentration-dependent fashion. The corresponding quenching rate constant (kq) is determined for the different spin labels. The kq values and the reduction rates of ESR signal show the same dependence on the localization of the nitroxyl moiety in the micelles. [less ▲]

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See detailHIV-1 promoter activation following an oxidative stress mediated by singlet oxygen
Legrand, Sylvie ULg; Hoebeke, Maryse ULg; Vaira, Dolorès ULg et al

in Journal of Photochemistry and Photobiology B : Biology (1993), 17(3), 229-237

Various biological processes, such as photosensitization or inflammatory reactions, can generate singlet oxygen (O-1(2)) as one of the major oxidative species. Because this oxidant can be generated either ... [more ▼]

Various biological processes, such as photosensitization or inflammatory reactions, can generate singlet oxygen (O-1(2)) as one of the major oxidative species. Because this oxidant can be generated either extracellularly or intracellularly, it can cause severe damage to various biological macromolecules, even to those deeply embedded inside the cells such as DNA. Sublethal biological modifications induced by different DNA-damaging agents can promote various cellular responses initiated by the activation of various cellular genes and certain heterologous viruses. Since O-1(2) fulfils essential prerequisites for a genotoxic substance, we have examined the effects of an oxidative stress, mediated by this species, on cells harbouring a heterologous promoter-leader sequence derived from the human immunodeficiency virus type 1 (HIV-1). Our results demonstrate that HIV-1 long terminal repeat (LTR), integrated into the cellular I)NA of epithelial cells, can be transactivated following an oxidative stress mediated by O-1(2). In addition, using HIV-1 latently infected promonocytes or lymphocytes, it can be shown that virus reactivation can be induced through a sublethal dose of O-1(2) generated intracellularly. An extracellular generation of O-1(2) can promote a substantial lethal effect without HIV-1 reactivation. These data may be relevant to the understanding of the events converting a latent infection into a productive one and to the appearance of the acquired immune deficiency syndrome. [less ▲]

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See detailHydroxyl radical generation by new furocoumarin derivatives: a spin trapping and ESR study
Collet, M.; Hoebeke, Maryse ULg; Piette, J. et al

Conference (1993)

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See detailMerocyanine 540 in liposomes: a laser flash photolysis and a electron resonance study
Hoebeke, Maryse ULg; Enescu, M.; Lindqvist, L. et al

Conference (1993)

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See detailHIV-1 reactivation after an oxidative stress
Legrand, Sylvie ULg; Hoebeke, Maryse ULg; Vaira, Dolorès ULg et al

in Archives Internationales de Physiologie, de Biochimie et de Biophysique (1992), 100

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See detailPhotosensitized Production of Singlet Oxygen by Merocyanine 540 Bound to Liposomes
Hoebeke, Maryse ULg; Piette, Jacques ULg; van de Vorst, A.

in Journal of Photochemistry and Photobiology B : Biology (1991), 9(3-4), 281-94

The production of singlet oxygen by merocyanine 540 was studied in dimyristoyl-phosphatidylcholine liposomes using two singlet oxygen probes: 9,10-anthracenedipropionic acid (water soluble) and 9,10 ... [more ▼]

The production of singlet oxygen by merocyanine 540 was studied in dimyristoyl-phosphatidylcholine liposomes using two singlet oxygen probes: 9,10-anthracenedipropionic acid (water soluble) and 9,10-dimethylanthracene (liposoluble). Upper and lower limits of singlet oxygen quantum yield for bound merocyanine 540 were determined to be 0.055 and 0.015 respectively. The diffusion characteristics of singlet oxygen were examined using the isotropic enhancement effect of D2O and the inhibitory effect of sodium azide. It was shown that 1O2 spent more than 87% of its lifetime in a vesicle environment. When the singlet-reacting substrate and the dye were both located in the bilayer, approximately 40% of the singlet oxygen remained in the liposomes where it was originally generated. [less ▲]

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See detailPotentialités photosensibilisatrices de la Merocyanine 540.
Hoebeke, Maryse ULg

Doctoral thesis (1991)

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See detailType 1 and Type 2 photosensitization mechanisms induced by merocyanine 540 bound to DMPC liposomes
Hoebeke, Maryse ULg; Piette, J.; Van de Vorst, A.

Conference (1991)

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See detailTriplet Yield of Merocyanine 540 in Water Is Wavelength Dependent
Seret, Alain ULg; Hoebeke, Maryse ULg; Van de Vorst, Albert

in Photochemistry and Photobiology (1990), 52(3), 601-604

Monomers and aggregates of Merocyanine 540 (MC540) in water are able to photoisomerize. The shape of the photoisomer absorption spectrum is very similar to that of the ground state. Triplet state of MC540 ... [more ▼]

Monomers and aggregates of Merocyanine 540 (MC540) in water are able to photoisomerize. The shape of the photoisomer absorption spectrum is very similar to that of the ground state. Triplet state of MC540 in water has been produced by energy transfer from triplet anthracene and displays a broad absorption spectrum between 600 and 700 nm. The triplet state may also be produced by direct excitation of MC540 with UV light. However, when the dye is excited by visible light, no triplet state absorbance in the red could be detected so that the triplet yield of MC540 in water seems to be excitation wavelength dependent. [less ▲]

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See detailViscosity-dependent isomerization and fluorescence yields of merocyanine 540
Hoebeke, Maryse ULg; Piette, J.; Van de Vorst, A.

in Journal of Photochemistry and Photobiology B : Biology (1990), 52

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