Newly designed polyacrylamide/dextran gels for electrophoresis protein separation: synthesis and characterization

Newly designed gels for electrophoresis protein separation were synthesized from acrylamide, N,N′‐methylenebis (acrylamide) and dextran mixtures. Radical polymerization was initiated by ammonium persulfate and N,N,N′,N′‐tetramethylethylenediamine. The time dependence of absorbance during polymerization was monitored using UV‐visible spectroscopy. The exothermic polymerization process exhibited a sharp rise of temperature reminiscent of the Trommsdorff effect. The swelling kinetics of the synthesized gels was examined in deionized water and buffer solutions. One of the challenges was to find an alternative to commercial products, sold as mixtures with no detailed chemical contents, commonly used in sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS‐PAGE) for protein separation. For this reason, a systematic comparison was made of the properties of one of the most commonly used commercial gels, Duracryl^? from Genomics Solution Inc., and those of the synthesized polyacrylamide/dextran gels. Copyright © 2011 Society of Chemical Industry     

Constructing protein models for ligand-receptor binding thermodynamic simulations: an application to a set of peptidometic renin inhibitors

Structure-based design is the application of ligand-receptor modeling to predict the activity of a series of molecules that bind to a common receptor for which the molecular geometry is available. Successful structure-based design requires an accurate receptor model which can be economically employed in the design calculations. One goal of the work reported here has been to reduce the size of a model structure of a macromolecular receptor to allow multiple ligand-receptor molecular dynamic (MD) simulations to be computationally economical yet still provide meaningful binding thermodynamic data. A scaled-down 10 A receptor model of the enzyme renin, when subjected to an alternate atomic mass constraint, maintains the structural integrity of the composite parent crystal structure. A second goal of the work has been to develop schemes to explore and characterize the protonation states of receptors and ligand-receptor systems. Application of the charge state characterization schemes to the hydroxyethylene and statine transition state inhibitors of renin in the training set suggests a monoprotonation state of the two active-site aspartate residues, where the lone proton resides on the outer carboxylate oxygen of Asp226 is most likely. For the reduced amide transition state inhibitors an active site consisting of both aspartates in the totally ionized state, and the ligand carrying a net +1.0 charge, is most stable and consistent with experimental data.     

Strain Localization During Compressive Deformation of Mg-Gd Alloy

Metallurgical and Materials Transactions A - Strain localization occurring at advanced deformation under compression of Mg-0.28 at. pctGd alloy has been studied. The strain localization develops in...     

Identification of protein remains in archaeological potsherds by proteomics

We demonstrate here the possibility of identifying proteins trapped in few milligrams of the clay matrix of a 1200-1400 AD I?upiat potsherd fragment from Point Barrow, Alaska, by a dedicated proteomics approach. The four main steps of a proteomics analysis, (i) protein extraction from biological samples, (ii) protein hydrolysis using a hydrolase enzyme, (iii) nanoLC, nanoESI MS, and MS/MS analysis of the generated peptides, and (iv) protein identification using protein databank proceeded from genomic data, have been optimized for archeological remains. Briefly our procedure starts by grinding the potsherds, extraction with 1% trifluoroacetic acid, digestion with excess of trypsin, nanoLC, nanoESI FT-ICR analysis, and data mining by homology search. The developed conditions were evaluated on protein extracts from remains obtained by heated muscle tissues and blubbers of different seal and whale species, these samples representing the main diet sources of the Eskimo population. Most of the proteins were identified by sequence homology to other species due to the lack of cetacean and pinniped proteins in the databanks. More interestingly, two proteins, myoglobin and hemoglobin, respectively, identified in muscle tissue samples and blubber samples highlight several specific peptides of cetacean and pinniped species; these peptides are significant to prove the presence of these marine species in the analyzed samples. Based on the developed methodology and on protein identification results obtained from the heated seal/whale muscle tissues and blubbers, the analysis of the clay matrix of a 1200-1400 AD I?upiat potsherd fragment from Point Barrow was investigated. The described method succeeds in identifying four peptides corresponding to the harbor seal myoglobin (species Phoca vitulina) with a measured mass accuracy better than 1 ppm (MS and MS/MS experiments) including one specific peptide of the cetacean and pinniped species and one specific peptide of the seal species. These results highlight, for the first time, a methodology able to identify proteins from a few milligrams of archeological potsherd buried for years; the obtained results confirm the presence of a seal muscle tissue protein in this Punuk potsherd.     

Contribution of Hypothyroidism to Cognitive Impairment and Hippocampal Synaptic Plasticity Regulation in an Animal Model of Depression

The role that thyroid hormone deficiency plays in depression and synaptic plasticity in adults has only begun to be elucidated. This paper analyzes the possible link between depression and hypothyroidism in cognitive function alterations, using Wistar–Kyoto (WKY—an animal model of depression) rats and control Wistar rats under standard and thyroid hormone deficiency conditions (propylthiouracil administration—PTU). A weakening of memory processes in the WKY rats is shown behaviorally, and in the reduction of long-term potentiation (LTP) in the dentate gyrus (DG) and CA1 hippocampal regions. PTU administration decreased LTP and increased basal excitatory transmission in the DG in Wistar rats. A decrease in short-term synaptic plasticity is shown by the paired-pulse ratio measurement, occurring during hypothyroidism in DG and CA1 in WKY rats. Differences between the strains may result from decreases in the p-CaMKII, p-AKT, and the level of acetylcholine, while in the case of the co-occurrence of depression and hypothyroidism, an increase in the p-ERK1-MAP seemed to be important. Obtained results show that thyroid hormones are less involved in the inhibition of glutamate release and/or excitability of the postsynaptic neurons in WKY rats, which may indicate a lower sensitivity of the hippocampus to the action of thyroid hormones in depression.     

Strain-induced martensite reversion in 18Cr–8Ni steel – transmission Kikuchi diffraction study

ABSTRACT

Reverse transformation of strain-induced martensite (SIM) was studied in the 18Cr–8Ni stainless steel. Microstructure analysis was performed on samples in an as-deformed state and after reversion annealing at 873 and 973?K, using the transmission Kikuchi diffraction. The primary, as well as reversed, austenite possesses the Kurdjumov–Sachs crystallographic orientation relationship, with respect to the SIM. The reverted austenite keeps one orientation within all reverted grains, regardless of the applied heating procedure, where the amount of reverted austenite depends only on the annealing temperature.     

Analysis and optimization of structure-based virtual screening protocols. 2. Examination of docked ligand orientation sampling methodology: mapping a pharmacophore for success

An important element of any structure-based virtual screening (SVS) technique is the method used to orient the ligands in the target active site. This has been a somewhat overlooked issue in recent SVS validation studies, with the assumption being made that the performance of an algorithm for a given set of orientation sampling settings will be representative for the general behavior of said technique. Here, we analyze five different SVS targets using a variety of sampling paradigms within the DOCK, GOLD and PROMETHEUS programs over a data set of approximately 10,000 noise compounds, combined with data sets containing multiple active compounds. These sets have been broken down by chemotype, with chemotype hit rate used to provide a measure of enrichment with a potentially improved relevance to real world SVS experiments. The variability in enrichment results produced by different sampling paradigms is illustrated, as is the utility of using pharmacophores to constrain sampling to regions that reflect known structural biology. The difference in results when comparing chemotype with compound hit rates is also highlighted.     

High-cycle fatigue bending strength of rapidly solidified and plastic consolidated RS442 aluminium alloy

Grain refinement in metallic materials down to submicro and nano scale results in improvement of mechanical properties. However, increase in strength under static load is not always accompanied by improved fatigue behaviour. In the current studies microstructure and mechanical properties of the submicrocrystalline RS442 aluminium alloy (chemical composition corresponds to conventional 442 cast alloy) were investigated. The alloy was subjected to rapid solidification followed by the extrusion process (variant 1) and additional annealing at 450 °C (variant 2). Rapidly solidified alloy was also consolidated with addition of graphite (variant 3). As the reference material conventionally cast and extruded alloy was also tested (variant 4). For all material variants strength properties were tested in static tensile test and high-cycle stress-controlled fatigue bending tests. It was found that rapid solidification and plastic consolidations led to increase of static mechanical properties of 442 alloy but reduced its fatigue strength.     

Medical express ... physician practice management

There's a hot new acronym in town, and investors from Wall Street to your street are paying attention. Physician management companies--better known as PMCs--are the newest force in the health care market. But is this bigger-is-better approach alienating more people than it's attracting? And how long before the boom goes burst?     

The Investigation of Strain-Induced Martensite Reverse Transformation in AISI 304 Austenitic Stainless Steel

This paper presents a comprehensive study on the strain-induced martensitic transformation and reversion transformation of the strain-induced martensite in AISI 304 stainless steel using a number of complementary techniques such as dilatometry, calorimetry, magnetometry, and in-situ X-ray diffraction, coupled with high-resolution microstructural transmission Kikuchi diffraction analysis. Tensile deformation was applied at temperatures between room temperature and 213 K (−60 °C) in order to obtain a different volume fraction of strain-induced martensite (up to ~70 pct). The volume fraction of the strain-induced martensite, measured by the magnetometric method, was correlated with the total elongation, hardness, and linear thermal expansion coefficient. The thermal expansion coefficient, as well as the hardness of the strain-induced martensitic phase was evaluated. The in-situ thermal treatment experiments showed unusual changes in the kinetics of the reverse transformation (α′ → γ). The X-ray diffraction analysis revealed that the reverse transformation may be stress assisted—strains inherited from the martensitic transformation may increase its kinetics at the lower annealing temperature range. More importantly, the transmission Kikuchi diffraction measurements showed that the reverse transformation of the strain-induced martensite proceeds through a displacive, diffusionless mechanism, maintaining the Kurdjumov–Sachs crystallographic relationship between the martensite and the reverted austenite. This finding is in contradiction to the results reported by other researchers for a similar alloy composition.