Direct analysis of laser capture microdissected endometrial carcinoma and epithelium by matrix-assisted laser desorption/ionization mass spectrometry

Direct analysis of laser capture microdissected malignant and normal endometrial epithelium using matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry (MS) was able to detect a number of proteins that are overexpressed in malignant epithelial cells. A total of 16 physiologic and malignant endometrial samples were laser capture microdissected, including four proliferative and four secretory endometria, and eight endometrioid adenocarcinomas. Two of these proteins, at 10,834 and 10,843 Da, likely correspond to calgranulin A and chaperonin 10, two proteins that had previously been identified in endometrioid adenocarcinoma in whole tissue homogenate by MS analysis. Direct analysis by MALDI-MS not only confirms that these proteins are overexpressed in endometrial carcinoma, but also localizes them to the epithelial cells, the expected cancer site.     

Novel magnetic supports for small molecule affinity capture of proteins for use in proteomics

Magnetic supports are tested for use in batch affinity capture of proteins. Two types of magnetic polymer composites were used for solid phase synthesis and for the batch affinity chromatography of folate binding protein from a protein mixture. Gly-Gly-L-Methotrexate as well as other analogs were synthesized on magnetic supports consisting of either polyoxyalkyleneamine grafted onto polystyrene beads or a copolymer of polyethylene glycol dimethylacrylamide (PEGA). Both supports incorporated within their matrix sub-micron particles of paramagnetic magnetite. The peptide-methotrexate analogs were attached to the magnetic supports via a photocleavable linker. The bound methotrexate-peptide analogs were equilibrated with a protein mixture consisting of bovine albumin, chicken albumin, folate binding protein, lysozyme, lactoferrin and lactoperoxidase precursor in phosphate buffered saline (PBS) and then after magnetically separating and washing the supports of any unbound components the bound protein was removed either through the photocleavage of the tethered methotrexate-peptide ligand or via exchange with soluble methotrexate. In all cases, the photocleavage or exchange with soluble methotrexate released folate binding protein as the major affinity captured protein. Of the two magnetic supports tested, the PEGA based support was found to be superior to the polyoxyalkyleneamine grafted polystyrene support and comparable to beaded agarose in releasing bound folate binding protein. Of the two methods for removing bound protein, photocleavage of the covalently attached ligand was found to release exclusively folate binding protein as opposed to exchange with soluble methotrexate which released residual amounts of the non-specifically bound proteins bovine and chicken albumin, in addition to folate binding protein. Thus, use of the PEGA based magnetic support in conjunction with a photocleavable linker should help facilitate the automation of multiple parallel affinity chromatography for proteomics applications.     

Phase diagrams of lyotropic cholesteric fluids

Experimental investigations of lyotropic cholesterics fluids are presented which show that changes in the shape anisotropy and chirality of the micellar population determine the topology of the temperature-concentration phase diagrams. For given amounts of the substances which induce the chirality and modify the shape anisotropy of the micelles, two distinct biaxial cholesteric phases are disclosed in the phase diagrams. This is interpreted in the framework of the catastrophe theory of phase transitions.     

Mimicking the Electromagnetic Distribution in the Human Brain: A Multi-frequency MRI Head Phantom

The purpose of this study was to fabricate and test a multi-frequency human brain-mimicking phantom for magnetic resonance imaging (MRI) assessment purposes. An anatomically realistic human head phantom was elaborated, for different Larmor frequencies, which allows rapid quantification of \({\text{B}}_{1}^{ + }\). It is a simple alternative solution in time and cost as compared to numerical simulations to validate simulation when the coil geometry and components cannot be known as a unique solution. The permittivity \(\varepsilon^{{\prime }}\) and conductivity \(\sigma\) of sucrose/salt/agar aqueous solutions of varying concentrations were determined; a solution with these components and having the adequate concentration to obtain the brain’s dielectric properties at 3, 7 and 11.7T was manufactured. An anthropomorphic polymeric skull was filled with this mixture. To check the behavior of this phantom in a MRI configuration, both numerical and experimental validations were done: a \({\text{B}}_{1}^{ + }\) field distribution inside the phantom was calculated with CST Microwave Studio inside a birdcage coil at 7T; the same mapping was assessed in a 7T MRI. The feasibility of a multi-MRI static field phantom was demonstrated. A solution composed by 54.7 wt% of sucrose, 3.1 wt% of salt and 3.1 wt% of agar was fabricated with good permittivity and conductivity matching for 3, 7 and 11.7T. The results were confirmed by both numerical simulation and MRI acquisition. This work has shown the possibility of manufacturing a head phantom with accessible and cheap components for MRI evaluation, having an adequate \({\text{B}}_{1}^{ + }\) field distribution and the dielectric properties of the human brain.     

ON THE ROLE OF FORBIDDEN LOW-LYING EXCITED STATES OF LIGHT-HARVESTING CAROTENOIDS IN ENERGY TRANSFER IN PHOTOSYNTHESIS*

Abstract—It is proposed that the low-lying. electric-dipole forbidden A_g excited electronic state recently discovered in β-carotene acts as the energy donor in Förster-type excitation transfer to antenna Chl molecules folbwing β-carotene's light-harvesting function in photosynthesis. The mechanism and conclusion should apply as well to all carotenoid accessory pigments.     

Alkoxyamine-mediated radical cyclizations

[reaction: see text] We present a new "conjunctive" radical cyclization process that involves the reaction of a 1,6-diene with the Tordo alkoxyamine, an agent originally developed for the radical polymerization of certain olefins through the "persistent radical effect".     

Functionalized porous silicon surfaces as MALDI-MS substrates for protein identification studies

Alkyl monolayer modified porous silicon functional surfaces are employed for selective binding of proteins from complex mixtures (through washing of the deposited mixture spot using appropriate buffer) and MALDI-MS is used to detect the components retained on the surface.     

NMR studies of preferential solvation of sodium cation in mixtures of N-methylformamide with water and some nonaqueous solvents

Sodium-23 NMR chemical shifts and linewidths have been measured for 0.1M NaClO₄ in binary mixtures of N-methylformamide (NMF) with a series of other solvents, as a function of the solvent mole fraction. The relative solvent composition at the isosolvation point, the mid-value of the Na-23 chemical shift between those measured in the respective pure solvents, reveals preferential solvation of the sodium cation in many cases. The isosolvation composition correlates well with the relative solvating abilities of the two solvents-as characterized by their donicities-provided that the cation-solvent interactions are of the hard-hard type and that they are not complicated by interionic interactions. The variation in the electric field gradient around the sodium nucleus, as the composition of the solvent changes, results in broadening of the resonance line. Maximum broadening occurs close to the solvent mole fraction corresponding to the isosolvation point.