Overexpression of ecto-5'-nucleotidase promotes P-glycoprotein expression in renal epithelial cells

P-glycoprotein (P-gp), responsible for multidrug resistance (MDR) of tumoral cells, is also expressed in apical membranes of normal epithelial cells, among which are proximal tubular cells. Ecto-5'-nucleotidase (5'Nu), co-located with P-gp in renal brush border membranes, could be instrumental in the expression of MDR phenotype. P-gp activity [assessed by rhodamine 123 (R123) and [3H]vinblastine (3H-VBL) accumulation] was evaluated in MDCK cell lines in which human 5'Nu was expressed at different levels after retroviral infection: MDCK-5'NU/- cells with a low 5'Nu activity (Vmax < 2 pmol/mg protein/min) and MDCK-5'NU/+ cells, which expressed a high level of 5'Nu (Vmax 150 +/- 18.5 pmol/mg protein/min). MDCK-5'NU/- cells did not display functional expression of MDR. In MDCK-5'NU/+ cells, R123 and 3H-VBL accumulation was significantly lower than in MDCK-5'NU/- cells and was dramatically enhanced by P-gp inhibitors. This high P-gp activity in MDCK-5'NU/+ cells was confirmed by their resistance to colchicine (measured by LDH release and MTT assay) as compared to MDCK-5'NU/- and was accounted for by increased membrane expression of P-gp assessed by Western blot. Neither AMP nor adenosine, the substrate and the product of 5'Nu, respectively, affected P-gp activity. Inhibition of 5'Nu with alpha beta-methylene-adenosine-diphosphate (alpha beta MADP) or with a blocking anti-5'Nu antibody (1E9) did not blunt MDR expression in MDCK-5'NU/+ cells. Conversely, the anti-5'Nu antibody 5F/F9, which did not block the enzymatic site, induced a decrease of P-gp activity. Further, incubation of MDCK-5'NU/- cells with conditioned medium from MDCK-5'NU/+ cells, which contained significant amounts of released 5'Nu, induced MDR phenotype. In conclusion: (i) expression of ecto-5'Nu promotes multidrug resistance (MDR) activity in renal epithelial cells by enhancement of P-gp expression; (ii) this effect does not involve enzymatic activity of 5'Nu; (iii) supernatants of cells that express 5'Nu conferred P-gp activity to 5'Nu negative cells.     

Characteristic properties of continuous annealed low-carbon low-aluminium steels

Continuous annealed low-carbon low-aluminium steel grades with good aging resistance and bake-hardenability were investigated. Taking into account the amounts of solute carbon and nitrogen in supersaturated ferrite it was tried to optimize the steel composition. Aging sensitivity depends mainly on solute nitrogen though the contribution to aging of solute carbon cannot be neglected. A reduced nitrogen aging requires a low nitrogen content (20 ppm) as well as Al/N ratios not lower than 5 and carbon contents higher than 0,025%. Both, low amounts of solute carbon and decrease of ferrite grain sizes of steels coiled at 650°C increase the effect of bake hardening. In comparison with aged steels the yield strength of overaged steels is conservative after baking. Bake-hardenable steels with good aging resistance are obtained in the carbon range 0,025 to 0,030%. Optimization according to the r?-value is not achieved in this range.     

Dynamic compaction of calcium phosphate biomaterials

The purpose of this study was to apply the dynamic compaction process to calcium phosphate biomaterials. this new technique is currently used to compact metallic powders at room temperature but has not been previously applied to biomaterials. A detailed study of hydroxyapatite compacts was carried out to determine shock compaction parameters. Low static precompaction (3.1 MPa) resulted in slight peripheral cracks. A compaction degree of about 70% and macrohardness of 51 Hv were achieved for a striker velocity of about 50 m/s. FTIR spectroscopy and X-ray diffraction showed no differences in structure and composition after dynamic compaction. Two other infrequently used biomaterials were also tested: an unstable octacalcium phosphate and -calcium metaphosphate fibres. Scanning electron microscopy showed that dynamic compaction preserved the initial fibre structure of the material. No major structural or chemical changes were noted after shock consolidation. Our results show that dynamic compaction could extend the range of bioceramics.     

COmmunication and WORKload analyses to study the COllective WORK of fighter pilots: the COWORK2 method

Cognition, Technology & Work - This paper presents the COWORK2 method, designed to classify the collective tasks of a fighter jet patrol according to two classification criteria: mental...     

Determination of the ionization energies and electron affinities of some dyes of photographic importance

Matsen equations are used in order to calculate, for the investigated compounds, related series of ionization potentials and electron affinities in gaseous phase, aqueous solution and in the photographic emulsion.More especially, peak and conventional polarographies are used to determine the oxidation and reduction potential terms as well as the work function of graphite. The solvation energy terms are evaluated on the basis of Born equation.It appears that reliable values of electron affinities in the emulsion for cyanine dyes are better determined from corresponding values of their ionization energies and values of transition energies obtained from sensitization spectra.     

Control-oriented aspirated masses model for variable-valve-actuation engines

Modelling the cylinder filling process on variable-valve-actuation equipped spark-ignition engines is addressed in this paper. It is developed using first principles equations for the aspirated gas masses. These analytic equations include cylinder-peripheral thermodynamic conditions along with the intake and exhaust valve lift histories. Following a general formulation of the breathing phenomenon, a versatile model is proposed for any type of variable valve gear device. Two particular cases of variable-valve-timing and camless equipped engines are detailed. The model is calibrated using experimental data obtained at test bench. For both cases, good representativeness of the model shows the relevance of the approach.     

Multigan®: first experimental results

A new design of a multicharged ion source based on the MONO1000 ECRIS has been presented at the last ECR ion source (ECRIS) Workshop 2010. [L. Maunoury et al., in Proceedings of the XIXth International Workshop on ECR Ion Sources, Grenoble, France, 23-26 August 2010] This source has not only two opening at both ends but also a large space in the middle of the source enabling a direct contact with the ECR plasma. The source has been assembled mechanically and put on a test bench at the Pantechnik company. The primary tests have shown that the plasma ignition occurred at low pressure (10(-6) mbar) and low RF power (10 W). The first experimental results ( = 1.30 for Ar and 1.85 for Xe) demonstrated the potential of this ion source in production of multicharged ion beams.     

Electronic Structure and Solvation Effects from Core and Valence Photoelectron Spectroscopy of Serum Albumin

X-ray photoelectron spectroscopy of bovine serum albumin (BSA) in a liquid jet is used to investigate the electronic structure of a solvated protein, yielding insight into charge transfer mechanisms in biological systems in their natural environment. No structural damage was observed in BSA following X-ray photoelectron spectroscopy in a liquid jet sample environment. Carbon and nitrogen atoms in different chemical environments were resolved in the X-ray photoelectron spectra of both solid and solvated BSA. The calculations of charge distributions demonstrate the difficulty of assigning chemical contributions in complex systems in an aqueous environment. The high-resolution X-ray core electron spectra recorded are unchanged upon solvation. A comparison of the valence bands of BSA in both phases is also presented. These bands display a higher sensitivity to solvation effects. The ionization energy of the solvated BSA is determined at 5.7 ± 0.3 eV. Experimental results are compared with theoretical calculations to distinguish the contributions of various molecular components to the electronic structure. This comparison points towards the role of water in hole delocalization in proteins.