Personne :
Lefèvre, Thierry

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Structures organisationnelles
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Lefèvre
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Thierry
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Université Laval. Département de chimie
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ncf10636490
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Résultats de recherche

Voici les éléments 1 - 3 sur 3
  • Publication
    Accès libre
    Using infrared and raman microspectroscopies to compare ex vivo involved psoriatic skin with normal human skin
    (SPIE, 2015-06-17) Lefèvre, Thierry; Auger, Michèle; Laroche, Gaétan; Leroy, Marie; Pouliot, Roxane
    Psoriasis is a chronic dermatosis that affects around 3% of the world’s population. The etiology of this autoimmune pathology is not completely understood. The barrier function of psoriatic skin is known to be strongly altered, but the structural modifications at the origin of this dysfunction are not clear. To develop strategies to reduce symptoms of psoriasis or adequate substitutes for modeling, a deep understanding of the organization of psoriatic skin at a molecular level is required. Infrared and Raman microspectroscopies have been used to obtain direct molecular-level information on psoriatic and healthy human skin biopsies. From the intensities and positions of specific vibrational bands, the lipid and protein distribution and the lipid order have been mapped in the different layers of the skin. Results showed a similar distribution of lipids and collagen for normal and psoriatic human skin. However, psoriatic skin is characterized by heterogeneity in lipid/protein composition at the micrometer scale, a reduction in the definition of skin layer boundaries and a decrease in lipid chain order in the stratum corneum as compared to normal skin. A global decrease of the structural organization is exhibited in psoriatic skin that is compatible with an alteration of its barrier properties.
  • Publication
    Accès libre
    Transdermal diffusion, spatial distribution and physical state of a potential anticancer drug in mouse skin as studied by diffusion and spectroscopic techniques
    (IOS Press, 2018-05-07) Lefèvre, Thierry; Le, Quoc-Chon; Auger, Michèle; Laroche, Gaétan; C. Gaudreault, René.
    Background:Understanding the efficiency of a transdermal medical drug requires the characterization of its diffusion process, including its diffusion rate, pathways and physical state. Objective:The aim of this work is to develop a strategy to achieve this goal. Methods:FTIR spectroscopic imaging in conjunction with a Franz cell and HPLC measurements were used to examine the transdermal penetration of deuterated tert-butyl phenylchloroethylurea (tBCEU), a molecule with a potential anticancer action. tBCEU has been solubilized in an expedient solvent mixture and its diffusion in hairless mouse skin has been studied. Results:The results indicate that tBCEU diffuses across the skin for more than 10 hours with a rate comparable to selegiline, an officially-approved transdermal drug. IR image analyses reveal that after 10 hours, tBCEU penetrates skin and that its spatial distribution does not correlate with neither the distribution of lipids nor proteins. tBCEU accumulates in cluster domains but overall low concentrations are found in skin. FTIR spectroscopic imaging additionally reveals that tBCEU is in a crystalline form. Conclusions:The results suggest that tBCEU is conveyed through the skin without preferential pathway. FTIR spectroscopic imaging and transdermal diffusion measurements appear as complementary techniques to investigate drug diffusion in skin.
  • Publication
    Restreint
    A surface spectroscopy study of a Pseudomonas fluorescens biofilm in the presence of an immobilized air bubble
    (Elsevier, 2019-05-28) Lefèvre, Thierry; Greener, Jesse; Abbaszadeh Amirdehi, Mehran; Pousti, Mohammad
    A linear spectral mapping technique was applied to monitor the growth of biomolecular absorption bands at the bio-interface of a nascent Pseudomonas fluorescens biofilm during and after interaction with a surface-adhered air bubble. Attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectra were obtained in different locations in a microchannel with adequate spatial and temporal resolution to study the effect of a static bubble on the evolution of protein and lipid signals at the ATR crystal surface. The results reveal that the presence of a bubble during the lag phase modified levels of extracellular lipids and affected a surface restructuring process, many hours after the bubble's disappearance.