Relaxation of bulk and interfacial energies

In this paper we obtain an integral representation for the relaxation inBV(Ω; ? ^p ) of the functional $$u \mapsto \int\limits_\Omega {f(x.\nabla u(x))dx + \int\limits_{\sum _{(u)} } {\varphi (x,[u](x),v(x))dH_{N - 1} (x)} }$$ with respect to theBV weak * convergence.     

Direct Catalytic Enantio‐ and Diastereoselective Mannich Reaction of Isocyanoacetates and Ketimines

A catalytic asymmetric synthesis of imidazolines with a fully substituted β‐carbon atom by a Mannich‐type addition/cyclization reaction of isocyanoacetate pronucleophiles and N‐diphenylphosphinoyl ketimines has been developed. When a combination of a cinchona‐derived aminophosphine precatalyst and silver oxide was employed as a binary catalyst system, good reactivity, high diastereoselectivities (up to 99:1 d.r.), and excellent enantioselectivities (up to 99 % ee) were obtained for a range of substrates.     

High‐resolution high‐performance liquid chromatography with electrospray ionization mass spectrometry and tandem mass spectrometry characterization of a new isoform of human salivary acidic proline‐rich proteins named Roma‐Boston Ser22(Phos) → Phe variant

During a survey of human saliva by a top‐down reversed‐phase high‐performance liquid chromatography with electrospray ionization mass spectrometry approach, two proteins eluting at 27.4 and 28.4 min, with average masses of 15 494 ± 1 and 11 142 ± 1 Da, were detected in a subject from Boston. The Δmass value (4352 Da) of the two proteins was similar to the difference in mass values between intact (150 amino acids, [a.a.]) and truncated acidic proline‐rich proteins (aPRPs; 106 a.a.) suggesting an a.a. substitution in the first 106 residues resulting in a strong reduction in polarity, since under the same experimental conditions aPRPs eluted at ～22.5 min (intact) and 23.5 min (truncated forms). Manual inspection of the high‐resolution high‐performance liquid chromatography with electrospray ionization tandem mass spectra of the truncated isoform showed the replacement of the phosphorylated Ser‐22 in PRP‐3 with a Phe residue. Inspection of the tandem mass spectra of the intact isoform confirmed the substitution, which is allowed by the code transition TCT→TTT and is in agreement with the dramatic increase in elution time. The isoform was also detected in two other subjects, one from Boston (unrelated to the previous) and one from Rome. For this reason we propose to name this variant PRP‐1 (PRP‐3) RB (Roma‐Boston) Ser₂₂(phos)→Phe.     

Glycosaminoglycan profiling in different cell types using infrared spectroscopy and imaging

We recently identified vibrational spectroscopic markers characteristic of standard glycosaminoglycan (GAG) molecules. The aims of the present work were to further this investigation to more complex biological systems and to characterize, via their spectral profiles, cell types with different capacities for GAG synthesis. After recording spectral information from individual GAG standards (hyaluronic acid, chondroitin sulfate, dermatan sulfate, heparan sulfate) and GAG-GAG mixtures, GAG-defective mutant Chinese hamster ovary (CHO)-745 cells, wild-type CHO cells, and chondrocytes were analyzed as suspensions by high-throughput infrared spectroscopy and as single isolated cells by infrared imaging. Spectral data were processed and interpreted by exploratory unsupervised chemometric methods based on hierarchical cluster analysis and principal component analysis. Our results showed that the spectral information obtained was discriminant enough to clearly delineate between the different cell types both at the cell suspension and single-cell levels. The abilities of the technique are to perform spectral profiling and to identify single cells with different potentials to synthesize GAGs. Infrared microspectroscopy/imaging could therefore be developed for cell screening purposes and further for identifying GAG molecules in normal tissues during physiological conditions (aging, healing process) and numerous pathological states (arthritis, cancer). Figure

FTIR imaging for profiling GAG-synthesizing cells     

Urine 2DE proteome analysis in healthy condition and kidney disease

Urine is a source of potential markers of disease. In the context of renal disease, urine is particularly important as it may directly reflect kidney injury. Current markers of renal dysfunction lack both optimal specificity and sensitivity, and improved technologies and approaches are needed. There is no clear consensus about the best sample pretreatment procedure for 2DE analysis of the urine proteome. Sample pretreatment conditions spots resolution and detection sensitivity, critically. As a first goal, we exhaustively compared eight different sample cleaning and protein purification methodologies for 2DE analysis of urine from healthy individuals. Oasis® HLB cartridges allowed the detection of the highest number of low molecular weight proteins; while PD10 desalting columns resulted in the highest number of detected spots in the high molecular weight area. Sample pretreatment strategies were also explored in the context of proteinuria, a clinical condition often associated to renal damage. Testing of urine samples from 13 patients with hypertension or kidney disease and different levels of proteinuria identified Oasis® HLB cartridge purification in combination with albumin depletion by ProteoPrep kit as the best option for urine proteome profiling from patients with proteinuric (> 30 mg/L albumin in urine) renal disease.     

Simultaneous Determination of Impurities in Ropinirole Tablets by an Improved HPLC Method Coupled with Diode Array Detection

A gradient HPLC method coupled with diode array detection was developed and fully validated for the analysis of impurities in ropinirole using a Kromasil^® C8 100 Å (250 × 4.6 mm, 5 μm) column with a flow rate 1.0 mL min^?1 and detection at 250 nm. The mobile phase component A consisted of a mixture of 19.6 mM aqueous potassium dihydrogen phosphate–acetonitrile (98:2 v/v), pH adjusted to 7.0 with triethylamine and the mobile phase component B consisted of acetonitrile. The method was validated in terms of linearity, sensitivity, precision, accuracy and stability. The calibration curves for ropinirole and its five impurities showed good linearity (r > 0.998) within the calibration ranges tested. The intra- and inter-day RSD values were <3.9 %, while the relative percentage error E _r was <5.8 % for all compounds. Accelerated stability studies performed under various stress conditions including oxidation, hydrolysis and UV light irradiation at 254 nm proved the selectivity of the procedure. Long-term stability studies performed on blistered tablets and under various conditions of heat and humidity indicate the presence of four of the studied impurities in less than 0.07 %. The method was applied successfully to the detection and determination of ropinirole impurities in pharmaceutical formulations.     

A shotgun approach for the identification of platinum–protein complexes

A shotgun approach including peptide-based OFFGEL-isoelectric focusing (IEF) fractionation has been developed with the aim of improving the identification of platinum-binding proteins in biological samples. The method is based on a filter-aided sample preparation (FASP) tryptic digestion under denaturing and reducing conditions of cisplatin–, oxaliplatin–, and carboplatin–protein complexes, followed by OFFGEL-IEF separation of the peptides. Any risk of platinum loss is minimized throughout the procedure due to the removal of the reagents used after each stage of the FASP method and the absence of thiol-based reagents in the focusing buffer employed in the IEF separation. The platinum–peptide complexes stability after the FASP digestion and the IEF separation was confirmed by size exclusion chromatography-inductively coupled plasma-mass spectrometry (SEC-ICP-MS). The suitability of peptide-based OFFGEL-IEF fractionation for reducing the sample complexity for further nano-liquid chromatography-electrospray ionization-tandem mass spectrometry (nLC-ESI-MS/MS) analysis has been demonstrated, allowing the detection of platinum-containing peptides, with significantly lower abundance and ionization efficiency than unmodified peptides. nLC-MS/MS analysis of selected OFFGEL-IEF fractions from tryptic digests with different complexity degrees: standard human serum albumin (HSA), a mixture of five proteins (albumin, transferrin, carbonic anhydrase, myoglobin, and cytochrome-c) and human blood serum allowed the identification of several platinum–peptides from cisplatin–HSA. Cisplatin-binding sites in HSA were elucidated from the MS/MS spectra and assessed considering the protein three-dimensional structure. Most of the potential superficial binding sites available on HSA were identified for all the samples, including a biologically relevant cisplatin-cross-link of two protein domains, demonstrating the capabilities of the methodology.

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Graphical Abstract Graphical abstract shows the several steps involved in the identification of platinum-protein complexes: FASP digestion of proteins, peptide fractionation by OFFGEL-IEF and identification of Pt-complexes by nLC-ESIMS/MS

     

A Potent,Selective and Cell‐Active Allosteric Inhibitor of Protein Arginine Methyltransferase 3 (PRMT3)

PRMT3 catalyzes the asymmetric dimethylation of arginine residues of various proteins. It is essential for maturation of ribosomes, may have a role in lipogenesis, and is implicated in several diseases. A potent, selective, and cell‐active PRMT3 inhibitor would be a valuable tool for further investigating PRMT3 biology. Here we report the discovery of the first PRMT3 chemical probe, SGC707, by structure‐based optimization of the allosteric PRMT3 inhibitors we reported previously, and thorough characterization of this probe in biochemical, biophysical, and cellular assays. SGC707 is a potent PRMT3 inhibitor (IC₅₀=31±2 nM , K_D=53±2 nM ) with outstanding selectivity (selective against 31 other methyltransferases and more than 250 non‐epigenetic targets). The mechanism of action studies and crystal structure of the PRMT3‐SGC707 complex confirm the allosteric inhibition mode. Importantly, SGC707 engages PRMT3 and potently inhibits its methyltransferase activity in cells. It is also bioavailable and suitable for animal studies. This well‐characterized chemical probe is an excellent tool to further study the role of PRMT3 in health and disease.