References of "Hoebeke, Maryse"
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See detailESR associated with spin-labelling methods into the study of photosensitization in liposomal solutions
Hoebeke, Maryse ULg

in Bulletin de la Société Royale des Sciences de Liège (2000)

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See detailApplications biomédicales de la RPE
Hoebeke, Maryse ULg

Scientific conference (1999, December)

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See detailFluorescence, Absorption and Electron Spin Resonance Study of Bacteriochlorin a Incorporation into Membrane Models
Hoebeke, Maryse ULg; Damoiseau, X.; Schuitmaker, H. J. et al

in Biochimica et Biophysica Acta (1999), 1420(1-2), 73-85

Analysis of the bacteriochlorin a absorption spectra suggests the existence of a monomer-dimer equilibrium, particularly intense in phosphate buffer and favored by a decrease of the pH. The dye in ... [more ▼]

Analysis of the bacteriochlorin a absorption spectra suggests the existence of a monomer-dimer equilibrium, particularly intense in phosphate buffer and favored by a decrease of the pH. The dye in methanolic solution is predominantly in monomeric form. Fluorescence and electron spin resonance nitroxide spin labeling measurements indicate that incorporation into the lipid phase of dimyristoyl-L-alpha-phosphatidylcholine liposomes induces dye monomerization. Moreover, the molecules are bound in the external surface of the vesicles and a complete incorporation is ensured by a lipid-to-dye ratio greater than 125. [less ▲]

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See detailA spectroscopic study inside liposomes of propofol singlet oxygen quenching properties
Heyne, B.; Mouithys-Mickalad, Ange ULg; Hans, P. et al

Conference (1999)

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See detailIncrease of the bacteriochlorin a photosensitizing efficiency by incorporation in liposomes
Damoiseau, X.; Schuitmaker, H.; Hoebeke, Maryse ULg

Conference (1999)

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See detailESR study of Bacteriochlorin a incorporation into membranes models
Hoebeke, Maryse ULg

Scientific conference (1999)

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See detailElectron spin resonance study of basteriochlorin a incorporation into membranes models
Hoebeke, Maryse ULg; Damoiseau, X.; Schuitmaker, H. et al

Conference (1999)

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See detailElectron spin resonance study of basteriochlorin a incorporation into membranes models
Hoebeke, Maryse ULg; Damoiseau, X.; Schuitmaker, H. et al

Conference (1999)

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See detailPropofol reacts with peroxynitrite to form phenoxyl radicals. Demonstration by ESR
Mouithys-Mickalad, Ange ULg; Hans, Pol ULg; Deby-Dupont, Ginette et al

in Biochemical and Biophysical Research Communications (1998), 249(3), 833-837

Peroxynitrite (ONOO-), resulting from the reaction of nitric oxide with superoxide anion, is a powerful oxidant produced in activated macrophages, during ischemia-reperfusion processes as well as in ... [more ▼]

Peroxynitrite (ONOO-), resulting from the reaction of nitric oxide with superoxide anion, is a powerful oxidant produced in activated macrophages, during ischemia-reperfusion processes as well as in neurodegenerative disorders. This study investigated the reaction of the anesthetic agent propofol (PPF) with ONOO-, using electron spin resonance (ESR) and UV-visible spectrometry. Peroxynitrite was synthetized either from acidified hydrogen peroxide and nitrite, or from sodium azide and ozone. The addition of ONOO- to PPF in alkaline solution (pH 12) allowed to detect a, short lifetime, ESR signal corresponding to a phenoxyl radical. This finding was confirmed by a UV-visible study, resulting in the appearance of 427 nm peak and the disappearance of the peak located at 239 nm. The 291 nm peak remained unchanged. The identification of the end-product of the reaction of PPF with ONOO- needs further investigations. [less ▲]

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See detailThe antibiotic ceftazidime is a singlet oxygen quencher as demonstrated by ultra-weak chemiluminescence and by inhibition of AAP consumption.
Deby, Ginette ULg; Deby, C.; Mouithys-Mickalad, Ange ULg et al

in Biochimica et Biophysica Acta (1998), 1379(1), 61-8

We demonstrated that the cephalosporin antibiotic ceftazidime (CAZ) deactivated singlet oxygen (1O2). We then studied the mechanisms of the CAZ effects on the ultra weak chemiluminescence (uwCL ... [more ▼]

We demonstrated that the cephalosporin antibiotic ceftazidime (CAZ) deactivated singlet oxygen (1O2). We then studied the mechanisms of the CAZ effects on the ultra weak chemiluminescence (uwCL) associated with the energy decay of 1O2 generated by the Mallet reaction (H2O2 + HOCl --> HCl + H2O + 1O2), and on the anthracene-9,10-dipropionic acid (AAP) consumption by 1O2 generated by irradiation of Rose Bengal (RB). The uwCL generated by the Mallet reaction was amplified (6.2 times) by CAZ. The use of red and blue filters, which absorb radiation below 610 nm and between 470 and 700 nm respectively, demonstrated that CAZ increased the uwCL by a radiation emission at wavelengths shorter than the 633 and 704 nm wavelength emissions of 1O2. CAZ was excited by scavenging the energy excess of 1O2, which so returned to its fundamental state, while CAZ deactivated with light emission between 430-480 nm. CAZ also inhibited in a dose-dependent manner the consumption of AAP by 1O2 generated by the irradiation of RB. The protection of AAP by 5 x 10(-3) M CAZ was equivalent to that of 10(-3) M histidine and 3 X 10(-6) M sodium azide. This process of 1O2 deactivation will be useful in diseases characterized by an excessive PMN activation with a release of activated oxygen species. [less ▲]

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See detailPropofol reacts with peroxynitrite to form phenoxyl radicals. Demonstration by ESR
Mouithys-Mickalad, Ange ULg; Hans, P.; Deby-Dupont, G. et al

Conference (1998)

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See detailElectron Spin Resonance Evidence of the Generation of Superoxide Anion, Hydroxyl Radical and Singlet Oxygen During the Photohemolysis of Human Erythrocytes with Bacteriochlorin A
Hoebeke, Maryse ULg; Schuitmaker, H. J.; Jannink, L. E. et al

in Photochemistry & Photobiology (1997), 66(4), 502-8

Photodynamic therapy with bacteriochlorin a (BCA) as sensitizer induces damage to red blood cells in vivo. To assess the extent of the contributuion of reactive oxygen species (ROS) and to determine a ... [more ▼]

Photodynamic therapy with bacteriochlorin a (BCA) as sensitizer induces damage to red blood cells in vivo. To assess the extent of the contributuion of reactive oxygen species (ROS) and to determine a possible reaction mechanism, competition experiments with assorted ROS quenching or/and enhancing agents were performed in human erythrocytes as model system and in phosphate buffer. In the erythrocyte experiments, a 2% suspension was incubated with BCA for 1 h, washed with phosphate-buffered saline, resuspended and subsequently illuminated with a diode laser using a fluence rate of 2.65 mW/cm2. Potassium leakage and hemolysis were light and BCA dose dependent. Adding tryptophan (3.3 mM), azide (1 mM) or histidine (10 mM) to the erythrocyte suspension before illumination delayed the onset of K-leakage and hemolysis suggesting a type II mechanism. The D2O did not affect K-leakage nor photohemolysis. Adding mannitol (13.3 mM) or glycerol (300 nM) also caused a delay in the onset of K-leakage and hemolysis, suggesting the involvement of radicals. In phosphate buffer experiments, it was shown using electron spin resonance (ESR) associated with spin-trapping techniques that BCA is able to generate O2-. and OH. radicals without production of aqueous electron. Visible or UV irradiation of the dye in the presence of the spin trap 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) gave an ESR spectrum characteristic of the DMPO-hydroxyl radical spin adduct DMPO-OH. Addition of ethanol or sodium formate produced supplementary hyperfine splittings due to the respective CH3CHOH. and CO2-. radical adducts, indicating the presence of free OH.. Production of DMPO-OH was partly inhibited by superoxide dismutase (SOD), catalase and desferrioxamine, suggesting that the iron-catalyzed decomposition of H2O2 was partly involved in the formation of one part of the observed OH.. The complementary inhibition of DMPO-OH production by azide and 9,10-anthracenedipropionic acid (ADPA) was consistent with 1O2 production by BCA followed by reaction of 1O2 with DMPO and decay of the intermediate complex to form DMPO-OH and free OH.. All our results seem to indicate that BCA is a 50%/50% type 1/type 2 sensitizer in buffered aqueous solutions and confirmed that the dye-induced hemolysis of erythrocytes was cell caused by a mixed type 1/type 2 mechanism. [less ▲]

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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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