Publications

2009

• Multimodal Multiphoton Imaging of Human Eye Tissues
  
  • Aptel Florent
  • Olivier Nicolas
  • Deniset Ariane
  • Plamann Karsten
  • Denis P.
  • Legeais Jean-Marc
  • Schanne-Klein Marie-Claire
  • Beaurepaire Emmanuel
  Investigative Ophthalmology & Visual Science, Association for Research in Vision and Ophthalmology, 2009, 50, pp.E-Abstract 3693. Purpose:To evaluate three combined modalities of multiphoton microscopy, second-harmonic generation (SHG), third-harmonic generation (THG), and two-photon-excited fluorescence (2PEF) for imaging cornea and trabecular meshwork in human intact eye tissue. Methods:A tunable femtosecond laser chain ( = 700-1250 nm) comprising a titanium-sapphire laser oscillator and an optical parametric oscillator was used to produce 2PEF (380-620nm), SHG (/2=430 or 600nm) and THG (/3= 400nm). Eight corneoscleral discs from eye bank and seven fresh corneal buttons obtained after penetrating keratoplasty were examined with water-immersion objectives. Forward and backward signals were detected and compared. Results:The three imaging modalities provide complementary information on intact tissue over the entire thickness of the cornea. THG imaging reveals the tissue morphology, including the epithelium structure with sub-cellular resolution. Polarization-resolved THG microscopy reveals stromal birefringent domains. In phenol-stained corneas, THG also reveals the keratocytes network. SHG imaging probes the distribution of stromal collagen lamellas organization. 2PEF imaging reveals the elastic component of the extra-cellular matrix and the distribution of fluorescent organelles (i.e. mitochondria) in stromal and epithelial cells. The trabeculum images show the three-dimensional organisation of the trabecular lamellas. Emission is predominantly forward directed for THG and SHG but in some cases, images can be recorded in the epi-direction. Conclusions:The combined imaging modalities of SHG, THG, and 2PEF microscopy are effective methods to evaluate cornea and trabecular meshwork microstructures in situ. This imaging approach should prove particularly appropriate for assessing corneal and glaucoma physiopathology, and might be amenable to in vivo diagnostics.
• Measurement of the Second-Order Hyperpolarizability of the Collagen Triple Helix and Determination of Its Physical Origin
  
  • Deniset-Besseau Ariane
  • Duboisset Julien
  • Benichou Emmanuel
  • Hache François
  • Brevet Pierre-Francois
  • Schanne-Klein Marie-Claire
  Journal of Physical Chemistry B, American Chemical Society, 2009, 113 (40), pp.13437-13445. We performed Hyper-Rayleigh Scattering (HRS) experiments to measure the second-order nonlinear optical response of the collagen triple helix and determine the physical origin of second harmonic signals observed in collagenous tissues. HRS experiments yielded a second-order hyperpolarizability of 1.25 x 10(-27) esu for rat-tail type I collagen, a Surprisingly large value considering that collagen presents no strong harmonophore in its amino acid sequence. Polarization-resolved experiments showed intramolecular coherent contributions to the HRS signal along with incoherent contributions that are the only contributions for molecules with dimensions much smaller than the excitation wavelength. We therefore modeled the effective second-order hyperpolarizability of the 290 nm long collagen triple helix by summing coherently the nonlinear response of well-aligned moieties along the triple helix axis. This model was confirmed by HRS measurements after denaturation of the collagen triple helix and for a collagen-like short model peptide [(Pro-Pro-Gly)(10)](3). We concluded that the large collagen nonlinear response originates in the tight alignment of a large number of small and weakly efficient harmonophores, presumably the peptide bonds, resulting in a coherent amplification of the nonlinear signal. (10.1021/jp9046837)
  DOI : 10.1021/jp9046837
• Single europium-doped nanoparticles measure temporal pattern of reactive oxygen species production inside cells
  
  • Casanova Didier
  • Bouzigues Cédric
  • Nguyên Thanh-Liêm
  • Ramodiharilafy Rivo O.
  • Bouzhir-Sima Latifa
  • Gacoin Thierry
  • Boilot Jean-Pierre
  • Tharaux Pierre-Louis
  • Alexandrou Antigoni
  Nature Nanotechnology, Nature Publishing Group, 2009, 4 (9), pp.581. Low concentrations of reactive oxygen species, notably hydrogen peroxide (H 2 O 2), mediate various signalling processes in the cell. Production of these signals is highly regulated and a suitable probe is needed to measure these events. Here, we show that a probe based on a single nanoparticle can quantitatively measure transient H 2 O 2 generation in living cells. The Y 0.6 Eu 0.4 VO 4 nanoparticles undergo photoreduction under laser irradiation but re-oxidize in the presence of oxidants, leading to a recovery in luminescence. Our probe can be regenerated and reliably detects intracellular H 2 O 2 with a 30-s temporal resolution and a dynamic range of 1-45?M. The differences in the timing of intracellular H 2 O 2 production triggered by different signals were also measured using these nanoparticles. Although the probe is not selective towards H 2 O 2, in many signalling processes H 2 O 2 is, however, the dominant oxidant. In conjunction with appropriate controls, this probe is a powerful tool for unravelling pathways that involve reactive oxygen species. Cop. 2009 Macmillan Publishers Limited. All rights reserved. (10.1038/nnano.2009.200)
  DOI : 10.1038/nnano.2009.200
• Apports récents des techniques de quantification de la fibrose pour l'examen anatomopathologique en transplantation rénale
  
  • Servais A.
  • Meas-Yedid V.
  • Morelon E.
  • Strupler Mathias
  • Schanne-Klein Marie-Claire
  • Legendre C.
  • Olivo-Marin J.-C.
  • Thervet É.
  Médecine/Sciences, EDP Sciences, 2009, 25 (11), pp.945-950. La néphropathie chronique d'allogreffe constitue la cause principale de perte des greffons rénaux à long terme. Elle peut être détectée précocement par des biopsies de dépistage effectuées de manière systématique. La classification usuelle, semi-quantitative, souffre d'une mauvaise reproductibilité. Diverses méthodes morphométriques ont donc été développées pour quantifier la fibrose interstitielle qui caractérise cette néphropathie. Certaines utilisent la coloration spécifique par le rouge Sirius. L'analyse d'image couleur par segmentation permet une quantification automatique, rapide et robuste de la fibrose interstitielle. Elle utilise une segmentation couleur associée à une analyse de couleur, de localisation spatiale et de forme sur des biopsies colorées au trichrome de Masson. À l'avenir, l'étude des collagènes fibrillaires par la génération de second harmonique pourrait permettre une approche spécifique des composants de la fibrose. (10.1051/medsci/20092511945)
  DOI : 10.1051/medsci/20092511945
• Unobtrusive interferometer tracking by path length oscillation for multidimensional spectroscopy
  
  • Lee Kevin F.
  • Bonvalet Adeline
  • Nuernberger Patrick
  • Joffre Manuel
  Optics Express, Optical Society of America - OSA Publishing, 2009, 17 (15), pp.12379-12384. We track the path difference between interferometer arms with few-nanometer accuracy without adding optics to the beam path. We measure the interference of a helium-neon beam that copropagates through the interferometer with midinfrared pulses used for multidimensional spectroscopy. This can indicate motion, but not direction. By oscillating the path length of one arm with a mirror on a piezoelectric stack and monitoring the oscillations of the recombined helium-neon beam, the direction can be calculated, and the path delay can be continuously tracked. © 2009 Optical Society of America. (10.1364/OE.17.012379)
  DOI : 10.1364/OE.17.012379
• Suppression of perturbed free-induction decay and noise in experimental ultrafast pump-probe data
  
  • Nuernberger Patrick
  • Lee Kevin F.
  • Bonvalet Adeline
  • Polack Thomas
  • Vos Marten H.
  • Alexandrou Antigoni
  • Joffre Manuel
  Optics Letters, Optical Society of America - OSA Publishing, 2009, 34 (20), pp.3226-3228. We apply a Fourier filtering technique for the global removal of coherent contributions, like perturbed freeinduction decay, and noise, to experimental pump-probe spectra. A further filtering scheme gains access to spectra otherwise only recordable by scanning the probe's center frequency with adjustable spectral resolution. These methods cleanse pump-probe data and allow improved visualization and simpler analysis of the contained dynamics. We demonstrate these filters using visible pump/mid-infrared probe spectroscopy of ligand dissociation in carboxyhemoglobin. Cop. 2009 Optical Society of America. (10.1364/OL.34.003226)
  DOI : 10.1364/OL.34.003226
• Heme ligand binding properties and intradimer interactions in the full-length sensor protein Dos from Escherichia coli and its isolated heme domain
  
  • Lechauve C.
  • Bouzhir-Sima Latifa
  • Yamashita Taku
  • Marden M.C.
  • Vos Marten H.
  • Liebl Ursula
  • Kiger L.
  Journal of Biological Chemistry, American Society for Biochemistry and Molecular Biology, 2009, 284 (52), pp.36146. Dos from Escherichia coli is a bacterial gas sensor protein comprising a heme-containing gas sensor domain and a phosphodiesterase catalytic domain. Using a combination of static light scattering and gel filtration experiments, we established that, as are many other sensor proteins, the full-length protein is dimeric. The full-length dimer (association constant <10 nm) is more stable than the dimeric heme domain (association constant ∼1 μm), and the dimer interface presumably includes both sensor and catalytic domains. Ultrafast spectroscopic studies showed little influence of the catalytic domain on kinetic processes in the direct vicinity of the heme. By contrast, the properties of ligand (CO and O2) binding to the heme in the sensor domain, occurring on a microsecond to second time scale, were found to be influenced by (i) the presence of the catalytic domain, (ii) the dimerization state, and in dimers, (iii) the ligation state of the other subunit. These results imply allosteric interactions within dimers. Steady-state titrations demonstrated marked cooperativity in oxygen binding to both the full-length protein and the isolated heme domain, a feature not reported to date for any dimeric sensor protein. Analysis of a variety of time-resolved experiments showed that Met-95 plays a major role in the intradimer interactions. The intrinsic binding and dissociation rates of Met-95 to the heme were modulated ∼10-fold by intradimer and sensor-catalytic domain interactions. Dimerization effects were also observed for cyanide binding to the ferric heme domains, suggesting a similar role for Met-95 in ferric proteins. (10.1074/jbc.M109.066811)
  DOI : 10.1074/jbc.M109.066811
• Femto-second ultrashort laser wakefield electron bunch-duration measurements: a prism-based dispersion visible-to-IR spectrometer
  
  • Lim J.
  • Faure Jérôme
  • Gallot Guilhem
  • Lundh O.
  • Rechatin C.
  • Malka Victor
  , 2009, pp.735919. (10.1117/12.829134)
  DOI : 10.1117/12.829134
• Extended fano model of extraordinary electromagnetic transmission through subwavelength hole arrays in the terahertz domain
  
  • Masson Jean-Baptiste
  • Podzorov Alexander
  • Gallot Guilhem
  Optics Express, Optical Society of America - OSA Publishing, 2009, 17 (17), pp.15280-15291. We developed an extended Fano model describing the Extraordinary Electromagnetic Transmission (EET) through arrays of subwavelength apertures, based on terahertz transmission measurements of arrays of various hole size and shapes. Considering a frequency-dependent coupling between resonant and non-resonant pathways, this model gives access to a simple analytical description of EET, provides good agreement with experimental data, and offers new parameters describing the influence of the hole size and shape on the transmitted signal. Cop. 2009 Optical Society of America. (10.1364/OE.17.015280)
  DOI : 10.1364/OE.17.015280
• Removing cross-phase modulation from midinfrared chirped-pulse upconversion spectra
  
  • Lee Kevin F.
  • Nuernberger Patrick
  • Bonvalet Adeline
  • Joffre Manuel
  Optics Express, Optical Society of America - OSA Publishing, 2009, 17 (21), pp.18738-18744. We observe that narrow spectral features in mid-infrared spectra obtained by chirped-pulse up-conversion are strongly distorted by crossphase modulation between the mid-infrared field and the chirped pulse. We discuss the consequences of this effect on spectral resolution, and introduce a correction method that recovers masked lines. This simple correction can be applied either when the upconverted field is fully characterized, such as in multidimensional spectroscopy, or when causality can be used, such as in absorption spectroscopy, which we demonstrate experimentally. Cop.2009 Optical Society of America. (10.1364/OE.17.018738)
  DOI : 10.1364/OE.17.018738
• HIV-1 IN alternative molecular recognition of DNA induced by raltegravir resistance mutations
  
  • Mouscadet J.-F.
  • Arora Rakesh
  • André J.
  • Lambry Jean-Christophe
  • Delelis O.
  • Malet I.
  • Marcelin A.-G.
  • Calvez V.
  • Tchertanov L.
  Journal of Molecular Recognition, Wiley, 2009, 22 (6), pp.480-494. Virologic failure during treatment with raltegravir, the first effective drug targeting HIV integrase, is associated with two exclusive pathways involving either Q148H/R/K, G140S/A or N155H mutations. We carried out a detailed analysis of the molecular and structural effects of these mutations. We observed no topological change in the integrase core domain, with conservation of a newly identified V-shaped hairpin containing the Q148 residue, in particular. In contrast, the mutations greatly altered the specificity of DNA recognition by integrase. The native residues displayed a clear preference for adenine, whereas the mutant residues strongly favored pyrimidines. Raltegravir may bind to N155 and/or Q148 residues as an adenine bioisoster. This may account for the selected mutations impairing raltegravir binding while allowing alternative DNA recognition by integrase. This study opens up new opportunities for the design of integrase inhibitors active against raltegravir-resistant viruses. Copyright Cop. 2009 John Wiley and Sons, Ltd. Supporting information may be found in the online version of this article. (10.1002/jmr.970)
  DOI : 10.1002/jmr.970