Preparation from bovine colostrum of a fraction rich in latent transforming growth factor-β2 and cleared of most allergenic proteins by one-step Cibacron Blue chromatography

A strategy was developed for the preparation of a latent transforming growth factor-β2 (latent TGF-β2) rich fraction from bovine colostrum. Different conventional chromatography techniques were tested to investigate some physicochemical properties of latent TGF-β2 complexes to optimize their recovery. Three latent TGF-β2 forms were detected by gel filtration (600, 150–250 and 65–150 kDa). Cation exchange chromatography showed that the pI of latent TGF-β2 was above pH 7; hydrophobic interaction chromatography showed that the hydrophobicity of latent TGF-β2 was much higher than that of other whey proteins. Affinity chromatography on Cibacron Blue 3G was used to separate latent TGF-β2 and immunoglobulin G from the most immunogenic proteins, α-lactalbumin, β-lactoglobulin and albumin. Optimum conditions were determined: preparation of a fraction 26 times richer in TGF-β2 than in serocolostrum was obtained with a good yield (up to 70%) of TGF-β2, 80% of which was in the latent form.     

Influence of local porosity and local permeability on the performances of a polymer electrolyte membrane fuel cell

In the literature, many models and studies focused on the steady-state aspect of fuel cell systems while their dynamic transient behavior is still a wide area of research. In the present paper, we study the effects of mechanical solicitations on the performance of a proton exchange membrane fuel cell as well as the coupling between the physico-chemical phenomena and the mechanical behavior. We first develop a finite element method to analyze the local porosity distribution and the local permeability distribution inside the gas diffusion layer induced by different pressures applied on deformable graphite or steel bipolar plates. Then, a multi-physical approach is carried out, taking into account the chemical phenomena and the effects of the mechanical compression of the fuel cell, more precisely the deformation of the gas diffusion layer, the changes in the physical properties and the mass transfer in the gas diffusion layer. The effects of this varying porosity and permeability fields on the polarization and on the power density curves are reported, and the local current density is also investigated. Unlike other studies, our model accounts for a porosity field that varies locally in order to correctly simulate the effect of an inhomogeneous compression in the cell.     

Memory for gist and detail information in Alzheimer's disease and mild cognitive impairment.

Two experiments examined different forms of gist and detail memory in people with Alzheimer's disease (AD) and those with amnestic mild cognitive impairment (MCI). In Experiment 1, 14 AD, 14 MCI, and 22 control participants were assessed with the Deese-Roediger-McDermott paradigm. Results indicated that false recognition of nonstudied critical lures (gist memory) was diminished in the AD compared with the MCI and control groups; the two latter cohorts performed similarly. In Experiment 2, 14 AD, 20 MCI, and 26 control participants were tested on a text memory task. Results revealed that recall of both macropropositions (gist information) and micropropositions (detail information) decreased significantly in AD and in MCI as compared with control participants. This experiment also revealed that the impairment was comparable between gist and detail memory. In summary, the results were consistent across experiments in the AD but not in the MCI participants. The discrepancy in MCI participants might be explained by differences in the degree of sensitivity of the experimental procedures and/or by the differences in the cognitive processes these procedures assessed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Semantic integration in Xyleme: a uniform tree-based approach

Xyleme is a huge warehouse integrating XML data of the Web. Xyleme considers a simple data model with data trees and tree types for describing the data sources, and a simple query language based on tree queries with boolean conditions. The main components of the data model are a mediated schema modeled by an abstract tree type, as a view of a set of tree types associated with actual data trees, called concrete tree types, and a mapping expressing the connection between the mediated schema and the concrete tree types. The first contribution of this paper is formal: we provide a declarative model-theoretic semantics for Xyleme tree queries, a way of checking tree query containment, and a characterization of tree queries as a composition of branch queries. The other contributions are algorithmic and handle the potentially huge size of the mapping relation which is a crucial issue for semantic integration and query evaluation in Xyleme. First, we propose a method for pre-evaluating queries at compile time by storing some specific meta-information about the mapping into map translation tables. These map translation tables summarize the set of all the branch queries that can be generated from the mediated schema and the set of all the mappings. Then, we propose different operators and strategies for relaxing queries which, having an empty map translation table, will have no answer if they are evaluated against the data. Finally, we present a method for semi-automatically generating the mapping relation.     

Synthesis and biological characterisation of targeted pro-apoptotic peptide

We report herein the synthesis and in vitro assay of new, multimeric RGD-peptide conjugates for cell-targeted drug delivery. We generated a peptide scaffold comprising two functional domains, one a tumour blood vessel "homing" motif and the other a programmed cell-death-inducing peptide sequence. RGD peptides were selected to direct the molecular conjugate to alpha(V)beta(3) integrin-containing tumour cells. The pro-apoptotic (Lys-Leu-Ala-Lys-Leu-Ala-Lys)(2) peptide was found to be nontoxic outside cells, but toxic when internalized into targeted cells as it disrupted the mitochondrial membrane. The synthesis of these targeted pro-apoptotic conjugates was carried out by assembling three different units (that is, scaffold, RGD units and pro-apoptotic peptide) through chemoselective ligations. We show that one compound displays significant biological effect in alpha(V)beta(3) integrin-containing tumour cells.     

Morphology and Buckling of the Oxide Scale after Fe–9Cr Steel Oxidation in Water Vapor Environment

Oxidation of Metals - Under water vapor exposure at 550–560 °C, Fe–9Cr ferritic–martensitic steels form a triplex oxide scale made of an outer magnetite layer...     

The effect of surface energy, adsorbed RGD peptides and fibronectin on the attachment and spreading of cells on multiwalled carbon nanotube papers

We report that hydrophilic oxidized multiwalled carbon nanotube papers (CNPs) were efficient substrates for attachment, spreading, and proliferation of MG-63 cells. Complete spreading occurred in the first 4 h of culture even without complete serum or pre-adsorbed adhesion proteins such as collagen or fibronectin. By contrast, the density of adherent cell on hydrophobic CNPs was low. Spreading did not happen after 24 h of culture in absence of serum proteins and growth factors on such papers. Cell viability concomitantly decreased. We also observed that a short RGD peptide, designed to adsorb on both hydrophobic and hydrophilic CNPs, enhanced adhesion, spreading, and proliferation only on hydrophilic CNPs. By contrast, adsorbed fibronectin triggers cell adhesion and spreading on both types of CNPs. Our results show that the imitation of tissue basal membranes with the nanofibrous structure of CNPs is insufficient to trigger the proliferation and spread of cells. Chemical cues are also needed for cells to spread. CNPs, however, offer a better substrate for adhesion protein absorption than do non-porous polymers.     

Characteristics of microbial biofilm on wooden vats ('gerles') in PDO Salers cheese

The purpose of this study was to characterize microbial biofilms from 'gerles' (wooden vats for making PDO Salers cheese) and identify their role in milk inoculation and in preventing pathogen development. Gerles from ten farms producing PDO Salers cheese were subjected to microbial analysis during at least 4 periods spread over two years. They were distinguished by their levels of Lactobacillus (between 4.50 and 6.01 log CFU/cm(2)), Gram negative bacteria (between 1.45 and 4.56 log CFU/cm(2)), yeasts (between 2.91 and 5.57 log CFU/cm(2)), and moulds (between 1.72 and 4.52 log CFU/cm(2)). They were then classed into 4 groups according their microbial characteristics. These 4 groups were characterized by different milk inoculations (with either sour whey or starter culture, daily or not), and different washing procedures (with water or whey from cheese making). The farm gerles were not contaminated by Salmonella, Listeria monocytogenes or Staphylococcus aureus. Only one slight, punctual contamination was found on one gerle among the ten studied. Even when the milk was deliberately contaminated with L. monocytogenes and S. aureus in the 40 L experimental gerles, these pathogens were found neither on the gerle surfaces nor in the cheeses. Using 40 L experimental gerles it was shown that the microbial biofilms on the gerle surfaces formed in less than one week and then remained stable. They were mainly composed of a great diversity of lactic acid bacteria (Leuconostoc pseudomesenteroides, Lactococcus lactis, Lactobacillus casei, Lactobacillus plantarum, Lactobacillus hilgardii,…), Gram positive catalase positive bacteria (Curtobacterium flaccumfaciens, Curtobacterium oceanosedimentum Citrococcus spp., Brachybacterium rhamnosum, Kocuria rhizophila, Arthrobacter spp.…) and yeast (Kluyveromyces lactis, Kluyveromyces marxianus). In less than 1 min, even in a 500 L farm gerle, the gerle's microbial biofilm can inoculate pasteurized milk with micro-organisms at levels superior to those in raw milk.     

Effect of modification by Pt and manufacturing processes on the microstructure of two NiCoCrAlYTa bond coatings intended for thermal barrier system applications

Few studies have already shown that Pt influences the diffusion of aluminium and therefore the microstructure of β-NiAl or γ-Ni/γ′-Ni₃Al materials. Besides, several works have revealed that the addition of Pt to MCrAlY (M = Ni and/or Co) improves the oxidation/corrosion behavior of the material. Nevertheless, very few data have been published on the microstructure of such modified MCrAlYs. Then, the present work deals with the addition of Pt to two NiCoCrAlYTa coatings that differ by their manufacturing process. Characterization is carried out in order to understand the influence of Pt diffusion but also the effect of the manufacturing process on the final microstructure. The collected data from XRD, SEM, EDS and TEM analyses reveal that an Al uphill diffusion occurs during heat treatment due to the presence of the Pt layer. The Al diffusion from the NiCoCrAlYTa bulk to the Pt-rich surface is so extensive that no more β-phase remains within the core of the coating. Pt may also dissolve TaC, precipitates largely present in the non-modified NiCoCrAlYTa coatings. In addition to Pt, the microstructure of the NiCoCrAlYTa prior to Pt deposition and heat treatment, dependent on the NiCoCrAlYTa manufacturing process, greatly influences the final microstructure.