Temporally and spatially heterogeneous distribution of mTHPC in a murine tumor observed by two-color confocal fluorescence imaging and spectroscopy in a whole-mount model

Efficient intratumor delivery of anticancer drugs and photosensitizers is an important factor in the success of chemotherapy and photodynamic therapy, respectively. Unfortunately, their adequate and uniform intratumor distribution is impeded by several physiological barriers and by binding to tissue components. Measurement of gross tumor drug accumulation is a routine method of investigating the uptake and clearance of chemotherapy agents and photosensitizers but tells little about their extravascular spatial distribution. We use whole-mount two-color confocal fluorescence imaging and imaging spectroscopy of unprocessed excised murine tumor fragments to investigate the intratumor distribution of the photosensitizer meso-tetrahydroxyphenyl chlorin (mTHPC) as a function of distance from blood vessels perfused with 0.2 mum diameter fluorescent microspheres. Significant mismatches between drug and perfused vasculature are caused by heterogeneities in tumor blood supply. We describe complex microscopic mTHPC gradients that reverse dramatically relative to the perfused vasculature with time after injection. This imaging technique can be applied to screen the dynamic intratumor distribution of other fluorescent photosensitizers and anticancer drugs.     

Propriétés électriques des gels aqueux d'amphiphile

Summary This paper deals with the calculation of electrical conductivity in soap-water-systems. Two models are discussed and compared with experimental data.

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Zusammenfassung In der vorliegenden Arbeit werden zwei Modelle zur Berechnung der Leitf?higkeit in Seifen-Wasser-Mischungen beschrieben und mit experimentellen Daten verglichen.

     

Solvation and dissociation of the carbanionic barium salt of the double 1,1′diphenylethylene in tetrahydrofuran

Mono- and dicarbanionic derivatives of 4,4bis(1-phenylethylene)1,1-biphenyl) (BPB): are prepared by addition of cumyl-barium or polystyryl-barium to BPB in tetrahydrofuran (THF). Spectroscopic and conductimetric measurements on monoadduct solutions were carried out in a temperature range from –105 to 25°C. At low temperature these solutions show a large spectral shift, due to the equilibrium between tight and solvent separated ion pairs. The thermodynamic parameters of this two step ion pair solvation were determined and the corresponding dissociation constant was found to be K _d =1×10^–6 mol-dm^–3 at 20°C. Once the first addition completed, the remaining double bond of the monoadduct seems to be less reactive than those of the original BPB. The diadduct has been prepared in the presence of an excess of cumyl-barium, and characterized spectroscopically.     

Biodegradability of sol–gel silica microparticles for drug delivery

The biodegradability of porous sol–gel silica microparticles in physiological buffers has been investigated using a USP4 flow-through dissolution tester. In the open configuration, which most closely models in-vivo conditions, the particles dissolved rapidly at pH 7.4, with a rate dependent on the surface area and media flow rate. In the closed configuration, the fastest dissolving 4 mg silica sample was almost completely dissolved in 100 mL of buffer after 36 h. The initial dissolution rates appeared relatively linear but dropped off as dissolved SiO₂ concentrations approached 20–25 ppm. Addition of serum proteins acted to slow dissolution by 20–30%, suggesting a slower degradation in vivo. Silica microparticles administered for controlled release drug delivery would therefore be expected to be eliminated relatively rapidly from the body, depending on the sample size and local fluid flow conditions.     

Material order‐independent interface reconstruction using power diagrams

We have developed a new, multi‐material, piecewise linear interface reconstruction method that correctly locates the position of each material in the mesh cell and matches the required volume fractions with no material ordering required. This is different from other volume tracking interface reconstruction methods in which an improper material ordering may result in materials being incorrectly located within the cell. The new method utilizes a type of weighted Voronoi diagram, known as a power diagram, to reconstruct the interface from approximate material locations derived either from a particle model or quadrature formula. It works on structured and general polygonal grids, for an arbitrary number of materials and can be naturally extended to three dimensions. Published in 2007 by John Wiley & Sons, Ltd.     

Directly diode-pumped Yb3+:SrY4(SiO4)3O regenerative amplifier

We report a regenerative amplifier based on an Yb-doped apatite crystal: Yb3+:SrY4(SiO4)3O (Yb:SYS). We obtained 420-fs pulses at a central wavelength of 1066 nm with an energy of 100 microJ at 300 Hz after compression. To the best of our knowledge, this system is the first regenerative amplifier based on an Yb:SYS crystal and provides duration among the shortest ones generated by a directly diode-pumped regenerative amplifier.     

Three-dimensional electric field visualization utilizing electric-field-induced second-harmonic generation in nematic liquid crystals

An electric-field-induced second-harmonic-generation signal in a nematic liquid crystal is used to map the electric field in an integrated-circuit-like sample. Since the electric-field-induced second-harmonic-generation signal intensity exhibits a strong dependence on the polarization of the incident laser beam, both the amplitude and the orientation of the electric field vectors can be measured. Combined with scanning second-harmonic-generation microscopy, three-dimensional electric field distribution can be easily visualized with high spatial resolution of the order of 1 microm.     

Equivalent step-index profile for graded W-fibres: application to TE01 mode cut-off

Snyder's equivalent step-index method is extended to the case of graded profiles with a depressed cladding. This method is then used to determine the limit of monomode operation. Comparison with the results obtained by an exact numerical technique is made for a large variety of simulated profiles, including those with ripples in the cladding. Conclusions are drawn concerning the sensitivity of various profile-shapes to such ripple structure. The method is applied also to measured profiles, reconstructed by a well-known tomographic procedure. In this latter case a comparison is made with experimentally determined values.On leave from CNET, Lannion, France.