. Study of Neuronal Preconditioning by ESR

Poster (2007, April)

Etude de la Rameb par résonance paramagnétique électronique (RPE) et diffusion de neutrons aux petits angles (SANS)

Conference (2007)

Photochemistry of 2,6-diisopropylphenol (propofol)

in Photochemical & Photobiological Sciences (2006), 5(11), 1059-1067

The photochemistry of the anaesthetic agent propofol (PPF) was investigated in three different solvents of quite different polarity (cyclohexane, methanol and phosphate buffer pH 7) by means of nanosecond ... [more ▼]

The photochemistry of the anaesthetic agent propofol (PPF) was investigated in three different solvents of quite different polarity (cyclohexane, methanol and phosphate buffer pH 7) by means of nanosecond laser flash photolysis and absorption spectroscopy. GC-MS spectrometry measurements of PPF in cyclohexane have revealed the formation of two major products upon low intensity UV continuous irradiation of PPF in aerated solution: the diphenol derivative of PPF and 2,6-diisopropyl-p-benzoquinone (PPFQ). Only the diphenol compound was obtained in anaerobic solution. PPF phenoxyl radical (PPF ) generation has been assigned as the original step leading to the formation of both the diphenol compound and PPFQ in cyclohexane as revealed by laser flash photolysis at 266 nm and by electron paramagnetic resonance spectroscopy as well. Investigation of PPF by nanosecond flash photolysis at 266 nm in the other solvents revealed the occurrence of different photochemical processes depending on the nature and the polarity of the solvent. A reaction scheme is proposed in order to discuss the mechanism of reaction of PPF in all media. [less ▲]

An in vitro study of the modulating activity of indole derivatives on H2O2/hemic enzyme systems.

Poster (2006, May 12)

Imagerie médicale - bases physiques

Book published by Editions de l'Université de Liège (2006)

The book explains the physical foundations of the most common in-vivo medical imaging modalities. It is written for readers having a basic knowledge of physics. However the most essential physical ... [more ▼]

The book explains the physical foundations of the most common in-vivo medical imaging modalities. It is written for readers having a basic knowledge of physics. However the most essential physical phenomenon and their properties are described. Exploring the electromagnetic spectrum from the shortest to the longest wavelengths the book deals with nuclear imaging, RX imaging, endoscopy, thermography and MRI. Acoustic wave and ultrasonography is the next subject. The book ends with the digital image and a few radioprotection notions. [less ▲]

Study of neuronal cells preconditionning

Poster (2005, November 25)

Synoviocytes, not chondrocytes, release free radicals after cycles of anoxia/re-oxygenation

in Biochemical & Biophysical Research Communications (2005), 334(2), 669-673

By oxymetry and electron paramagnetic resonance (EPR), we investigated the effects of repeated anoxia/re-oxygenation (A/R) periods on the respiration and production of free radicals by synoviocytes ... [more ▼]

By oxymetry and electron paramagnetic resonance (EPR), we investigated the effects of repeated anoxia/re-oxygenation (A/R) periods on the respiration and production of free radicals by synoviocytes (rabbit HIG-82 cell line and primary equine synoviocytes) and equine articular chondrocytes. Three periods of 20 min anoxia followed by re-oxygenation were applied to 10(7)cells; O(2) consumption was measured before anoxia and after each re-oxygenation. After the last A/R, cellular free radical formation was investigated by EPR spectroscopy with spin trapping technique (n=3 for each cell line). Both types of synoviocytes showed a high O(2) consumption, which was slowered after anoxia. By EPR with the spin trap POBN, we proved a free radical formation. Results were similar for equine and rabbit synoviocytes. For chondrocytes, we observed a low O(2) consumption, unchanged by anoxia, and no free radical production. These observations suggest an oxidant activity of synoviocytes, potentially important for the onset of osteoarthritis. [less ▲]

Quantification of lipid bilayer effective microviscosity and fluidity effect induced by propofol

in Biophysical Chemistry (2005), 114(1), 53-61

Electron spin resonance (ESR) spectroscopy with nitroxide spin probes was used as a method to probe the liposome microenvironments. The effective microviscosities have been determined from the calibration ... [more ▼]

Electron spin resonance (ESR) spectroscopy with nitroxide spin probes was used as a method to probe the liposome microenvironments. The effective microviscosities have been determined from the calibration of the ESR spectra of the probes in solvent mixtures of known viscosities. In the first time, by measuring ESR order parameter (S ) and correlation time (s c) of stearic spin probes, we have been able to quantify the value of effective microviscosity at different depths inside the liposome membrane. At room temperature, local microviscosities measured in dimyristoyl-l-a phosphatidylcholine (DMPC) liposome membrane at the different depths of 7.8, 16.95, and 27.7 2 were 222.53, 64.09, and 62.56 cP, respectively. In the gel state (10 °C), those microviscosity values increased to 472.56, 370.61, and 243.37 cP. In a second time, we have applied this technique to determine the modifications in membrane microviscosity induced by 2,6-diisopropyl phenol (propofol; PPF), an anaesthetic agent extensively used in clinical practice. Propofol is characterized by a unique phenolic structure, absent in the other conventional anaesthetics. Indeed, given its lipophilic property, propofol is presumed to penetrate into and interact with membrane lipids and hence to induce changes in membrane fluidity. Incorporation of propofol into dimyristoyl-L-alpha-phosphatidylcholine liposomes above the phase-transition temperature (23.9 °C) did not change microviscosity. At 10 °C, an increase of propofol concentration from 0 to 1.0 10 [less ▲]

Study of neuronal cells preconditioning by ESR

Conference (2005)

Determination of the critical micelle concentration using ESR spin label method.

Poster (2005)