References of "Grammenos, Angeliki"
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See detailAn ESR, Mass Spectrometry and Fluorescence microscopy approach to study the stearic acid derivatives anchoring in cells
Grammenos, Angeliki ULg; Fillet, Marianne ULg; Collodoro, Mike et al

in Applied Magnetic Resonance (2012)

Lateral phase separations in biological membranes are of great interest, making Electron Spin Resonance (ESR) spectroscopy combined with spin labelling a non destructive and sensitive technique for the ... [more ▼]

Lateral phase separations in biological membranes are of great interest, making Electron Spin Resonance (ESR) spectroscopy combined with spin labelling a non destructive and sensitive technique for the study of lipid rafts. This is currently accepted that spin probe localization is on the plasma membrane. However, no study confirms this hypothesis. Herein, we report, for the first time, an accurate multi spectral method for the quantification of lipid spin label presence in every sub-cellular fraction. Cells were incubated with 5-doxyl stearic acid derivative and then sub-fractionated. Results of our multimodal spectroscopy approach ubiquitously demonstrate that the presence of ESR spin label only sets in the plasma membranes. [less ▲]

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See detailIn vitro ESR measurements: powerful tool to study toxic effects on cells
Grammenos, Angeliki ULg; Quoilin, Caroline ULg; Guelluy, Pierre-Henri ULg et al

Poster (2011, October)

Electron spin resonance spectroscopy (ESR) is a highly efficient technique able to access a wide range of information about the unfavourable effects caused by a chemical or a drug. ESR in spin labelling ... [more ▼]

Electron spin resonance spectroscopy (ESR) is a highly efficient technique able to access a wide range of information about the unfavourable effects caused by a chemical or a drug. ESR in spin labelling fits well in with the study of membranes and particularly with the changes in lipid bilayer organisation induced by drug. Our team previously developed a way to quantify the effective lipid bilayer microviscosity of cell membranes and consequently put in evidence the fluidity effect of the propofol. Recently, the importance of lipid raft domains has been shown due to their important role as a platform for signal transduction and protein sorting. We propose to highlight the effect of the Randomly methylated beta cyclodextrin (Rameb) on these domains on membrane model (liposomes) as well as on colon carcinoma cell line (HCT-116). Futhermore, ESR in spin trapping is used in order to identify and quantify the generation of Reactive Oxygen Species (ROS) in cells. An ESR study on human colon carcinoma cell line has highlighted the cytotoxicity of the photosensitizer pyrophephorbide-a methyl ester. Using an intracellular located spin trap (4-pyridyl 1-oxide-N-tert-butylnitrone, POBN), it has been shown that the photoexcitation of the dye is able to generate superoxide anions, hydroxyl radicals and singlet oxygen. Moreover, ESR is one of the most sensitive method for measuring cellular oxygen consumption. Our team has studied the alterations of oxygen respiratory in human tubular renal cells treated with an endotoxin (lipopolysaccharide, LPS). The incubation of HK-2 cells with LPS elicited a decreased in oxygen consumption suggesting a down-regulation of the cells metabolism. [less ▲]

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See detailEndotoxin-induced alterations in renal oxygen consumption: an ESR oximetry study
Quoilin, Caroline ULg; Grammenos, Angeliki ULg; Gallez, Bernard et al

Poster (2011, August)

The kidney, one of the most injured organs in critically ill patients, is faced with unique challenges for molecular oxygen regulation. Recent research activities in the pathophysiological mechanism of ... [more ▼]

The kidney, one of the most injured organs in critically ill patients, is faced with unique challenges for molecular oxygen regulation. Recent research activities in the pathophysiological mechanism of acute renal injury (ARI) emphasize the central role of hemodynamic and inflammatory events in septic shock. More particularly, two mechanisms have been postulated to explain the inability of the injured kidney to extract oxygen: tissue hypoxia and cellular energetic metabolism dysfunction. The present investigation was carried out to characterize the effects of bacterial endotoxin on the oxygen consumption of human tubular proximal cell line (PTC) by using the very sensitive electron spin resonance oximetry method. Oxygen consumption was shown to decrease quite markedly in cells treated with lipopolysaccharide (LPS) from 16.52 ± 2.51 (n=6) in the control group to: 12.94 ± 2.62 (n=3) in the short incubation time group (6h) and 10.86 ± 2.20 (n=3) in the long incubation time group (18h). This decrease in oxygen consumption in renal cells after LPS challenge may be in relation with a metabolic down-regulation. Renal energetic are deranged in sepsis not just because O2 delivery is impaired but perhaps also because the ability of cells to utilize available O2 is compromised. [less ▲]

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See detailESR technique for non invasive way to quantify cyclodextrins effect on cell membranes
Grammenos, Angeliki ULg; Mouithys-Mickalad, Ange ULg; Guelluy, Pierre-Henri ULg et al

in Biochemical and Biophysical Research Communications (2010)

A new way to study the action of cyclodextrin was developed to quantify the damage caused on cell membrane and lipid bilayer. The Electron Spin Resonance (ESR) spectroscopy was used to study the action of ... [more ▼]

A new way to study the action of cyclodextrin was developed to quantify the damage caused on cell membrane and lipid bilayer. The Electron Spin Resonance (ESR) spectroscopy was used to study the action of Randomly methylated-beta-cyclodextrin (Rameb) on living cells (HCT-116). The relative anisotropy observed in ESR spectrum of nitroxide spin probe (5-DSA and cholestane) is directly related to the rotational mobility of the probe,which can be further correlated with themicroviscosity. The use of ESR probes clearly shows a close correlation between cholesterol contained in cells and cellular membrane microviscosity. This study also demonstrates the Rameb ability to extract cholesterol and phospholipids in time- and dose-dependent ways. In addition, ESR spectra enabled to establish that cholesterol is extracted from lipid rafts to form stable aggregates. The present work supports that ESR is an easy, reproducible and noninvasive technique to study the effect of cyclodextrins on cell membranes. [less ▲]

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See detailMultiple spectroscopic study of in vitro photodynamic therapy induced by PPME
Guelluy, Pierre-Henri ULg; Quoilin, Caroline; Grammenos, Angeliki ULg et al

Conference (2010, June 01)

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See detailESR evidence of superoxide anion, hydroxyl radical and singlet oxygen generation during photosensitization of PPME in HCT-116 cells
Quoilin, Caroline ULg; Guelluy, Pierre-Henri ULg; Grammenos, Angeliki ULg et al

Poster (2010, March)

Pyropheophorbide-a methyl ester (PPME), a derivative of chlorophyll a, is a second-generation photosensitizer and is studying largely in vitro for nearly a decade on cancerous cells. It has been ... [more ▼]

Pyropheophorbide-a methyl ester (PPME), a derivative of chlorophyll a, is a second-generation photosensitizer and is studying largely in vitro for nearly a decade on cancerous cells. It has been previously established on HCT-116 (human colon carcinoma cell line) that PPME is a molecule able to create apoptotic and necrotic death (Matroule et al). The cytotoxicity of PPME is presumed to be induced by reactive oxygen species (ROS) generated by the photoexcited molecule. Actually, to the best of our knowledge, no experimental evidence enables to confirm this supposition in an indubitable manner. Electron spin resonance (ESR) associated with spin trapping technique is a powerful method to detect, quantify and identify the ROS produced after photoactivation of PPME. Previous results indicate that PPME penetrates inside cells and localizes inside specific organelles (endothelial reticulum, Golgi apparatus and lysosome) (Matroule et al). The recent researches of Guelluy et al have also clearly demonstrated the presence of PPME inside mitochondrion. Consequently, ESR experiments were performed using an intracellular located spin trap, POBN (4-pyridyl 1-oxide-N-tert-butylnitrone), in order to detect in situ the ROS production. It has been shown that PPME is able to generate superoxide anions and hydroxyl radicals. Irradiation of the dye in HCT-116 cells in the presence of POBN spin trap and ethanol scavenger (2%, a non-toxic concentration) leads to the apparition of the ESR spectrum characteristics of POBN/ethoxy adduct. To assess the extent of contribution of ROS and to determine a possible reaction mechanism, competition experiments with specific quencher agents were carried out. Addition of catalase (CAT), a hydrogen peroxide quencher, or superoxide dismutase (SOD), a superoxide anion quencher, inhibits 30% of the signal. The parallel effect of SOD and CAT suggest that superoxide anion and hydrogen peroxide are involved in the generation of hydroxyl radicals via a Fenton reaction. This assertion is reinforced by the 20% reduction of signal intensity when adding desferroxamine, a Fe3+ chelator also implicated in Fenton reaction. Addition of DABCO, a quencher of singlet oxygen, to cells reduces 70% of the POBN/ethoxy adduct signal intensity. [less ▲]

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See detailDevelopment of a new topical system: Drug-in-cyclodextrin-in-deformable liposome
Gillet, Aline ULg; Grammenos, Angeliki ULg; Compère, Philippe ULg et al

in International Journal of Pharmaceutics (2009), 380(1-2), 174-180

A new delivery system for cutaneous administration combining the advantages of cyclodextrin inclusion complexes and those of deformable liposomes was developed, leading to a new concept: drug ... [more ▼]

A new delivery system for cutaneous administration combining the advantages of cyclodextrin inclusion complexes and those of deformable liposomes was developed, leading to a new concept: drug-incyclodextrin-in-deformable liposomes. Deformable liposomes made of soybean phosphatidylcholine (PC) or dimyristoylphosphatidylcholine (DMPC) and sodium deoxycholate as edge activator were compared to classical non-deformable liposomes. Liposomes were prepared by the film evaporation method. Betamethasone, chosen as the model drug,was encapsulated in the aqueous cavity of liposomes by the use of cyclodextrins. Cyclodextrins allowan increase in the aqueous solubility of betamethasone and thus, the encapsulation efficiency in liposome vesicles. Liposome size, deformability and encapsulation efficiency were calculated. The best results were obtained with deformable liposomes made of PC in comparison with DMPC. The stability of PC vesicles was evaluated by measuring the leakage of encapsulated calcein on the one hand and the leakage of encapsulated betamethasone on the other hand. In vitro diffusion studies were carried out on Franz type diffusion cells through polycarbonate membranes. In comparison with non-deformable liposomes, these new vesicles showed improved encapsulation efficiency, good stability and higher in vitro diffusion percentages of encapsulated drug. They are therefore promising for future use in ex vivo and in vivo experiments. [less ▲]

Detailed reference viewed: 93 (31 ULg)
See detailPyropheophorbide-a-methyl ester: DMPC liposome vectorization and biophysical properties for PDT
Guelluy, Pierre-Henri ULg; Fontaine-Aupart, Marie-Pierre; Grammenos, Angeliki ULg et al

Poster (2009, July)

Detailed reference viewed: 19 (4 ULg)