References of "Evrard, Brigitte"
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See detailPEPTIDE-LOADED LIPOSOMES AGAINST BREAST CANCER: EFFECTIVE PENETRATION IN CELLS OF LONG CIRCULATING pH-SENSITIVE VESICLES
Ducat, Emilie ULg; Deprez, Julie ULg; Peulen, Olivier ULg et al

Poster (2010, October)

Purpose: Print3G, a peptidic antagonist of oncoprotein involved in breast cancer, could reduce the angiogenic development of breast tumors. The necessity of intravenous administration of Print3G led to ... [more ▼]

Purpose: Print3G, a peptidic antagonist of oncoprotein involved in breast cancer, could reduce the angiogenic development of breast tumors. The necessity of intravenous administration of Print3G led to the development of liposomes as drug carriers, combining the protective properties of PEG with the transfection properties of pH-sensitive lipids. The purpose of this work is to compare pegylated pH-sensitive liposomes with a classical formulation of long-circulating liposomes in terms of cellular uptake. Methods: Classical liposomes (SPC:CHOL:mPEG-750-DSPE (47:47:6 mol/mol)) and pH-sensitive liposomes (DOPE:CHEMS:CHOL: mPEG750-DSPE (43:21:30:6 mol/mol)) were compared in terms of size, charge, stability, pH-sensitivity and toxicity by inhibition of cell proliferation. Finally, confocal microscopy was used to study the cellular uptake of liposomes by three cell lines (Hs578t, WI-26 and MDA-MB-231), using 25-nitrobenzoxydiazol-cholesterol as a fluorescent marker of the vesicular membrane and rhodamine in the inner cavity of liposomes. Results: Sizes of 162.8 ± 4.6 nm and zeta potential of -9.3 ± 1.2 mV were obtained for standard liposomes (n=3) while the obtained values for pH-sensitive liposomes (n=3) were respectively of 184.8 ± 3.2 nm and -19.5 ± 2.6 mV. The two formulations were comparable in terms of shape and stability. Concerning the pH-sensitivity study, a significantly higher leakage of the encapsulated material was observed at pH 5 for pH-sensitive liposomes. Confocal pictures obtained with these vesicles on the three cell lines allowed us to visualize the colocalized red and green color with a higher concentration near the nucleus. Conclusion: Long circulating pH-sensitive liposomes are promising drug delivery systems in terms of cellular uptake. Experiments will be performed with biotinylated Print3G to assess its cellular distribution. Moreover, the accumulation of this formulation in breast tumor will be evaluated by in vivo studies. [less ▲]

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See detailInterest of vesicular systems in dermal drug delivery
Gillet, Aline ULg; Lecomte, Frédéric ULg; Hubert, Pascale ULg et al

Poster (2010, October)

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See detailNIR AND RAMAN SPECTROSCOPY AS PAT TOOLS FOR THE MANUFACTURING OF SILICONE-BASED DRUG RESERVOIRS
Mantanus, Jérôme ULg; Ziemons, Eric ULg; Van Butsele, Kathy et al

Conference (2010, September 24)

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See detailOptimisation and validation of a fast HPLC method for the quantitation of sulindac and its impurities
Krier, Fabrice ULg; Brion, Michaël; Debrus, Benjamin ULg et al

Poster (2010, September)

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See detailThe experimental design as practical approach to develop and optimize a formulation of peptide-loaded liposomes
Ducat, Emilie ULg; Brion, Michael; Lecomte, Frédéric ULg et al

in AAPS PharmSciTech (2010), 11(2), 966-975

To investigate the encapsulation of Print 3G, a peptidic agent that could reduce the angiogenic development of breast tumors, pegylated liposomes used as intravenous vectors were studied and characterized ... [more ▼]

To investigate the encapsulation of Print 3G, a peptidic agent that could reduce the angiogenic development of breast tumors, pegylated liposomes used as intravenous vectors were studied and characterized. Recently, the path of liposomes has been explored with success to improve the pharmacological properties of peptidic drugs and to stabilize them. In this study, loaded unilamellar vesicles composed of SPC:CHOL:mPEG2000-DSPE (47:47:6) were prepared by the hydration of lipid film technique. An HPLC method was developed and validated for the determination of Print 3G to calculate its encapsulation efficiency. Observed Print 3G adsorption on different materials employed during liposome preparation (such as glass beads, tubing, and connections for extrusion) led to the modification of the manufacturing method. The freeze-thawing technique was used to enhance the amount of Print 3G encapsulated into blank liposomes prepared using the hydration of lipid film procedure. Many factors may influence peptide entrapment, namely the number of freeze-thawing cycles, the lipid concentration, the peptide concentration, and the mixing time. Consequently, a design of experiments was performed to obtain the best encapsulation efficiency while minimizing the number of experiments. The lipid concentration and the number of freeze-thawing cycles were identified as the positive factors influencing the encapsulation. As a result of the optimization, an optimum was found and encapsulation efficiencies were improved from around 30% to 63%. Liposome integrity was evaluated by photon correlation spectroscopy and freeze-fracture electron microscopy to ensure that the selected formulation possesses the required properties to be a potential candidate for further in vitro and in vivo experiments. [less ▲]

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See detailTechnologie Pharmaceutique et Biopharmacie
Evrard, Brigitte ULg

Learning material (2010)

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See detailComparison of chitosan/siRNA and trimethylchitosan/siRNA complexes behaviour in vitro
Dehousse, Vincent ULg; Garbacki, Nancy ULg; Jaspart, Séverine ULg et al

in International Journal of Biological Macromolecules (2010), 46

Chitosan and trimethylchitosan (TMC)-siRNA nanoparticles were produced by simple complexation technique or by ionic gelation using tripolyphosphate (TPP). The obtained complexes were characterized in ... [more ▼]

Chitosan and trimethylchitosan (TMC)-siRNA nanoparticles were produced by simple complexation technique or by ionic gelation using tripolyphosphate (TPP). The obtained complexes were characterized in terms of physicochemical properties such as size, zeta potential, complexation efficiency and stability. Furthermore, cytotoxicity, cell uptake and transfection efficiency of polyplexes were evaluated in vitro. Under pH condition of cell culture medium, a strong decrease in siRNA condensation efficiency was observed with chitosan nanoparticles. This characteristic resulted in low transfection efficiencies in HEK293 cell line. Formulation of chitosan polyplexes with TPP led to improvement of polyplexes stability but no significant increase in transfection efficiency was observed compared to simple chitosan complexes. By contrast, TMC complexes did not have pH dependency on siRNA complexation. TMCsiRNA nanoparticles were stable in physiological condition. Accordingly, cellular uptake was increased compared to chitosan polyplexes. However, improvement of transfection efficiency was low regarding to cellular uptake of these complexes. Chitosan and TMC complexes present some characteristics favourable for siRNA delivery, such as ability to integrate siRNA into small discrete particles or low toxicity of the complexes. This study also highlights the importance of complexes stability in physiological environment for siRNA transfection purposes. [less ▲]

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See detailDevelopment of pH–responsive nanocarriers using trimethylchitosans and methacrylic acid copolymer for siRNA delivery
Dehousse, Vincent ULg; Garbacki, Nancy ULg; Colige, Alain ULg et al

in Biomaterials (2010), 31

RNA interference-based therapies are dependent on intracellular delivery of siRNA. The release of siRNA from the endosomal compartment may be a rate limiting step in the transfection process. The purpose ... [more ▼]

RNA interference-based therapies are dependent on intracellular delivery of siRNA. The release of siRNA from the endosomal compartment may be a rate limiting step in the transfection process. The purpose of this study was to produce pH–responsive nanocarriers made of trimethylchitosan (TMC). To this end, pHsensitive methacrylic acid (MAA) copolymer was added to TMC–siRNA formulations. Four different TMCs associated or not with MAA were evaluated as siRNA carriers. Nanoparticles were characterized in terms of size, surface charge, morphology and interaction with siRNA. A swelling behaviour due to a decrease in pH was observed and was found to be dependent on MAA content in the complexes. In vitro experiments aimed at evaluating how the capacity of the nanocarriers to transfect siRNA in L929 cells was affected by MAA content. Confocal microscopy experiments showed that fluorescent MAA-containing particles exhibit a different distribution pattern inside the cells comparing to their counterpart without this pH-sensitive polymer. Transfection efficiency was investigated by RhoA mRNA expression inhibition. MAA–TMC–siRNA complexes were able to transfect L929 cells with greater efficiency than corresponding TMC–siRNA complexes. This study gives an insight into the opportunity of pH-sensitive nanocarriers for siRNA delivery. Such formulations may represent an attractive strategy to improve endosomal escape of siRNA. [less ▲]

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See detailAcetaminophen determination in low-dose pharmaceutical syrup by NIR spectroscopy
Ziemons, Eric ULg; Mantanus, Jérôme ULg; Lebrun, Pierre ULg et al

in Journal of Pharmaceutical & Biomedical Analysis (2010), 53

The aim of the present study was first to develop a robust near infrared (NIR) calibration model able to determine the acetaminophen content of a low-dose syrup formulation (2 % (w/v)). Therefore ... [more ▼]

The aim of the present study was first to develop a robust near infrared (NIR) calibration model able to determine the acetaminophen content of a low-dose syrup formulation (2 % (w/v)). Therefore, variability sources such as production campaigns, batches, API concentration, syrup basis, operators and sample temperatures were introduced in the calibration set. A prediction model was then built using Partial Least Square (PLS) regression. First derivative followed by Standard Normal Variate (SNV) were chosen as signal pre-processing. Based on the random subsets cross validation, 4 PLS factors were selected for the prediction model. The method was then validated for an API concentration ranging from 16 to 24 mg/mL (1.6-2.4 % (w/v)) using an external validation set. The 0.26 mg/mL RMSEP suggested the global accuracy of the model. The accuracy profile obtained from the validation results, based on tolerance intervals, confirmed the adequate accuracy of the results generated by the method all over the investigated API concentration range. Finally, the NIR model was used to monitor in real time the API concentration while mixing syrups containing various amounts of API, a good agreement was found between the NIR method and the theoretical concentrations. [less ▲]

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See detailEffect of β-cyclodextrin and its derivatives on caveolae disruption, relationships with their cholesterol extraction capacities
Castagne, Delphine ULg; Evrard, Brigitte ULg; Nusgens, Betty ULg et al

in Journal of Inclusion Phenomena and Macrocyclic Chemistry (2010), 67

Endothelial cells (HUVEC) were treated with b-cyclodextrin (b-CD) and hydroxypropylated or methylated derivatives solutions to confirm their lack of affinity with phospholipids and their specificity ... [more ▼]

Endothelial cells (HUVEC) were treated with b-cyclodextrin (b-CD) and hydroxypropylated or methylated derivatives solutions to confirm their lack of affinity with phospholipids and their specificity towards cholesterol. Further studies were performed on bovine aortic endothelial cells to assess the effect of b-CDs (mainly methylated derivatives) on membrane microdomains (lipid rafts or caveolae), by detecting the caveolae marker caveolin-1 in fractions of sucrose gradients. A displacement from the lighter to the heavier fractions, characteristic of caveolae disruption, was observed using CDs. The strongest effect was obtained with dimethyl-b-CD, for which an accumulation of caveolin-1 was observed in the bottom of the gradient. Crysmeb and trimethyl-b-CD seemed to have the weaker effects as a significative amount of caveolin-1 was still detected in the light fraction corresponding to caveolae. b-CD and CDs having a degree of methylation a bit lower than 2 showed intermediate effects. The results of the present study on microdomains seem in good correlation with the cell cholesterol extraction capacities of CDs previously determined. [less ▲]

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