Optimization of a defined serum-free medium for the production of therapeutic human myoblasts

Duchenne Muscular Dystrophy (DMD) is a genetic disease affecting one boy out of 3500, which is due to a mutation in the dystrophin gene, inducing progressive and irreversible muscle degeneration. Cell therapy is the only means by which a DMD patient could recover part of his muscular mass and strength. We are presently collaborating with a team at the Quebec City University Hospital who is developing a cell therapy based on the graft to DMD patients of myoblasts obtained from biopsies on healthy and compatible donors. To do so, cells collected from donors need to be extensively multiplied. The standard culture medium allowing this multiplication contains foetal bovine serum (FBS). We have developed a serum-free medium (SFM) that supports cell growth to an extent and at a rate similar to the ones in FBS-containing medium. Cells grown in the developed SFM also show some typical myoblast phenotypes and functionalities such as: the presence of desmin and myosin heavy chain (MHC) and the capacity to fuse and form myofibers in vitro. However, cell morphology as well as the capacity to graft to muscle fibers in vivo are different for cells grown in the two culture media. We have therefore hypothesized that morphology was a marker of cell functionality in vivo, and have chosen to optimize our SFM with an objective function composed of both medium cost and cell morphology, while constraining to maintain cell growth rate and extent. To do so, we have used 1) statistical design of experiment response surface methodology combined with 2) undecimated wavelet transform multivariate non-invasive image analysis to screen the SFM components for optimum growth, medium cost and cell morphology. The optimized SFM (MSFM) we have found through this process is 55% less expensive than the original SFM, and the human myoblasts grown in this medium exhibit comparable growth, morphology and muscle fiber graft capacity as cells grown in FBS-containing medium

Dispersion of carbon nanotubes in polypropylene via multilayer coextrusion: Influence on the mechanical properties

The authors would like to thank PSA for funding this research and providing some of the materials used in this study. We also would like to thank R. Glénat, P. Soria, E. Dandeu, A. Grand- montagne and A. Dubruc for their help in the preparation and the optical and mechanical characterizations of the samples presented in this study.Multilayer coextrusion was used to disperse Carbon Nanotubes (CNT) in polypropylene (PP). The dilution of commercially available masterbatches using a twin-screw extruder was first applied to produce several formulations, which were then mixed with PP using a multilayer coextrusion device to obtain films or pellets with CNT concentrations between 0.1 and 1%wt. The influence of the specific mechanical energy (SME) during the dilution step, of the addition of a compatibilizer, and of the multilayer tool on the CNT dispersion within the matrix was highlighted. The effect of the dispersion on the thermomechanical properties of the resulting materials was studied. We showed notably that films containing 0.2%wt CNT, 1%wt of PPgAm, prepared at high SME presented a Young’s modulus increase of 25e30% without significant decrease in the elongation at break. These results, using low amounts of CNT and industrially available devices, may show a new path for producing nanocomposites

Oxidative degradation of polylactide (PLA) and its effects on physical and mechanical properties

The thermo-oxidative degradation of polylactide (PLA) films was studied between 70 and 150 C. It was shown that the oxidative degradation of PLA leads to a random chain cission responsible for a reduction of the molar mass. These molar mass changes affect Tg and the degree of crystallinity, and it was found that Tg decreases according to the Fox–Flory theory whereas the degree of crystallinity increases due to a chemicrystallization process. A correlation between molar mass and strain at break during oxidation has been established: PLA displays a brittle behavior when Mn falls below 40 kg mol 1 in agreement with relationships linking the critical value for embrittlement with the molar mass between entanglements

Chromosomal control of pig populations in France: 2002-2006 survey

The chromosomal control of pig populations has been widely developed in France over the last ten years. By December 31st, 2006, 13 765 individuals had been karyotyped in our laboratory, 62% of these since 2002. Ninety percent were young purebred boars controlled before service in artificial insemination centres, and 3% were hypoprolific boars. So far, 102 constitutional structural chromosomal rearrangements (67 since 2002) have been described. Fifty-six were reciprocal translocations and 8 peri- or paracentric inversions. For the first time since the beginning of the programme and after more than 11 000 pigs had been karyotyped, one Robertsonian translocation was identified in 2005 and two others in 2006. The estimated prevalence of balanced structural chromosomal rearrangements in a sample of more than 7700 young boars controlled before service was 0.47%. Twenty-one of the 67 rearrangements described since 2002 were identified in hypoprolific boars. All were reciprocal translocations. Twelve mosaics (XX/XY in 11 individuals, XY/XXY in one individual) were also diagnosed. Two corresponded to hypoprolific boars, and three to intersexed animals. The results presented in this communication would justify an intensification of the chromosomal control of French and, on a broader scale, European and North-American pig populations

Forced assembly by multilayer coextrusion to create oriented graphene reinforced polymer nanocomposites

A potential advantage of platelet-like nanofillers as nanocomposite reinforcements is the possibility of achieving two-dimensional stiffening through planar orientation of the platelets. The ability to achieve improved properties through in-plane orientation of the platelets is a challenge and, here, we present the first results of using forced assembly to orient graphene nanoplatelets in poly(methyl methacrylate)/ polystyrene (PMMA/PS) and PMMA/PMMA multilayer films produced through multilayer coextrusion. The films exhibited a multilayer structure made of alternating layers of polymer and polymer containing graphene as evidenced by electron microscopy. Significant single layer reinforcement of 118% at a concentration of 2 wt % graphene was achieveddhigher than previously reported reinforcement for randomly dispersed graphene. The large reinforcement is attributed to the planar orientation of the graphene in the individual polymer layers. Anisotropy of the stiffening was also observed and attributed to imperfect planar orientation of the graphene lateral to the extrusion flow

Capital-labor substitution and indeterminacy in continuous-time two-sector models

The aim of this paper is to discuss the role of the elasticity of capital-labor substitution on the local determinacy properties of the steady state in a two-sector economy with CES technologies and sector-specific externalities

Modulation of the texture of emulsified and acidified model systems by the addition of protein aggregates

Modulation of the texture of emulsified and acidified model systems by the addition of protein aggregates. Colloque Biopolymers 201

Exploratory behaviour in NO-dependent cyclase mutants of Drosophila shows defects in coincident neuronal signalling

<p>Abstract</p> <p>Background</p> <p><it>Drosophila </it>flies explore the environment very efficiently in order to colonize it. They explore collectively, not individually, so that when a few land on a food spot, they attract the others by signs. This behaviour leads to aggregation of individuals and optimizes the screening of mates and egg-laying on the most favourable food spots.</p> <p>Results</p> <p>Flies perform cycles of exploration/aggregation depending on the resources of the environment. This behavioural ecology constitutes an excellent model for analyzing simultaneous processing of neurosensory information. We reasoned that the decision of flies to land somewhere in order to achieve aggregation is based on simultaneous integration of signals (visual, olfactory, acoustic) during their flight. On the basis of what flies do in nature, we designed laboratory tests to analyze the phenomenon of neuronal coincidence. We screened many mutants of genes involved in neuronal metabolism and the synaptic machinery.</p> <p>Conclusion</p> <p>Mutants of NO-dependent cyclase show a specifically-marked behaviour phenotype, but on the other hand they are associated with moderate biochemical defects. We show that these mutants present errors in integrative and/or coincident processing of signals, which are not reducible to the functions of the peripheral sensory cells.</p

Miniaturized wireless cell spectrophotometer platform in visible and near-IR range

In this paper, a new miniaturized wireless cell spectrophotometer is presented. This system can scan a sample, detect incoming light power and transmit corresponding data to a base station for further analysis in the range of 340 nm to 850 nm. In vitro measurement results with VERO E6 cells tagged with DAPI and Alexa Fluor488 are presented to demonstrate its performance. The proposed system uses two small Lithium-ion batteries that provide a 7.4 V supply voltage. The system's low power consumption (88 mW), its minimal use of hardware resources, and its total weight of 17 g incorporated into a small wireless platform make the proposed device suitable for real-time implementation in most common low-power cell spectrophotometer applications