Rheological investigation of swollen gluten polymer networks: effects of process parameters on cross-link density

Wheat gluten samples were subjected to different thermo-mechanical treatments. Kinetics of protein aggregation and changes in network structure were investigated through biochemical and rheological measurements. Temperature induced protein aggregation through disulphide cross-links. Shear treatment alters the aggregation mechanism since a lower energy of activation was observed. Accumulation of aggregated protein enhances the elastic behaviour of the material. The strong correlation found between the extent of protein aggregation and the molecular weight between cross-links reveals the important role of covalent bonds in the network connectivity.     

Thermal and vibrational biomarkers of porcine oral mucosa

Journal of Thermal Analysis and Calorimetry - The aim of this study was to develop an experimental protocol to determine specific and reproducible biomarkers of the oral mucosa using a combination...     

A Validated RP-LC Method for the Determination of Isosorbide 5-Mononitrate in a Leishmanicidal Ointment

An RP-LC method using a YMC-Pack ODS-AQ column and UV detection (220 nm) was validated for the determination of isosorbide 5-mononitrate selected as an exogenous NO source in a leishmanicidal ointment. After extraction with hot water, the extracts were analysed at 35 °C using isocratic conditions (water-acetonitrile, 4:1 v/v; 0.9 mL min^?1). The method was specific, precise, accurate and linear.     

Design, synthesis, and cytotoxic activity of Michael acceptors and enol esters in the benzo[b]acronycine series

A series of 2-acyl-6-methoxy-3,3,14-trimethyl-3,14-dihydro-7H-benzo[b]pyrano[3,2-h]acridin-7-ones (4-6) was prepared by treatment of 6-methoxy-3,3,14-trimethyl-3,14-dihydro-7H-benzo[b]pyrano[3,2-h]acridin-7-one (3) with an excess of an appropriate acyl chloride in the presence of aluminum chloride. Treatment of (+/-)-cis-1-hydroxy-2-acyloxy-6-methoxy-3,3,14-trimethyl-1,2,3,14-tetrahydro-7H-benzo[b]pyrano[3,2-h]acridin-7-ones (9, 10) or (+/-)-cis-1,2-diacyloxy-6-methoxy-3,3,14-trimethyl-1,2,3,14-tetrahydro-7H-benzo[b]pyrano[3,2-h]acridin-7-ones (2, 11) with hydrochloric acid gave the corresponding 2-acyloxy-6-methoxy-3,3,14-trimethyl-3,14-dihydro-7H-benzo[b]pyrano[3,2-h]acridin-7-ones, exemplified by acetate 7 and butyrate 8. None of the Michael acceptors 4-6 showed significant antiproliferative activity. Enol esters 7 and 8 were markedly cytotoxic toward L1210 leukemia cells, with IC50 values within the same range of magnitude as (+/-)-cis-1,2-diacetoxy-6-methoxy-3,3,14-trimethyl-1,2,3,14-tetrahydro-7H-benzo[b]pyrano[3,2-h]acridin-7-one (S23906-1), currently under phase I clinical trials. In contrast with S23906-1, enol esters 7 and 8 were not reactive toward purified DNA.     

An asymptotically stable discretization for the Euler–Poisson system in the quasi-neutral limit

We are interested in the modeling of a plasma in the quasi-neutral limit using the Euler–Poisson system. When this system is discretized with a standard numerical scheme, it is subject to a severe numerical constraint related to the quasi-neutrality of the plasma. We propose an asymptotically stable discretization of this system in the quasi-neutral limit. We present numerical simulations for two different one-dimensional test cases that confirm the expected stability of the scheme in the quasi-neutral limit. To cite this article: P. Crispel et al., C. R. Acad. Sci. Paris, Ser. I 341 (2005).     

Regioselective photolabeling of glycoprotein A in membranes

We have developed a chemical method for directly identifying the amino acid residues of the transmembrane domain of a protein that are located right in the center of the membrane. Glycophorin A (GPA), the major sialoglycoprotein of human erythrocytes, was the first membrane protein whose primary sequence was elucidated, but its three-dimensional structure is still not known. GPA has been reconstituted into liposomes formed from dimyristoylphosphatidylcholine, dimyristoylphosphatidylserine, cholesterol, and a bola-amphiphilic phospholipidic photoactivatable probe (radioactive probe 1) by a detergent-mediated method. Electron microscopy confirmed the formation of spherical vesicular structures, and sucrose-density gradients revealed that the proteoliposomes comprised only one membrane fraction. Proteinase-K digestion of GPA in the proteoliposomes suggested that the orientation of GPA in reconstituted proteoliposomes was virtually identical to that observed in natural erythrocyte membranes. After photo-irradiation of the reconstituted proteoliposomes and in situ tryptic digestion, the photolabeled amino acid residues were analyzed by Edman degradation and their radioactivity was measured. Val80 and Met81, which had been assumed to be located near the center of the transmembrane domain of GPA, were indeed highly selectively photolabeled by probe 1. The new method might be applied to analyze the three-dimensional arrangement of the transmembrane domain of protein complexes that are made up from several subunits.