Thiuram Disulfides as Pseudo‐irreversible Inhibitors of Lymphoid Tyrosine Phosphatase

We screened a small library of thiuram disulfides for inhibition of lymphoid tyrosine phosphatase (LYP) activity. The parent thiuram disulfide, disulfiram, inhibited LYP activity in vitro and in Jurkat T cells, whereas diethyldithiocarbamate failed to inhibit LYP at the concentrations tested. Compound 13 , an N‐(2‐thioxothiazolidin‐4‐one) analogue, was found to be the most potent LYP inhibitor in this series, with an IC₅₀ value of 3 μM . Compound 13 inhibits LYP pseudo‐irreversibly, as evidenced by the time‐dependence of inhibition, with a K_i value of 1.1 μM and a k_inact value of 0.004 s^?1. The inhibition of LYP by compound 13 could not be reversed significantly by incubation with glutathione or by prolonged dialysis, but could be partially reversed by incubation with dithiothreitol. Compound 13 also inhibited LYP activity in Jurkat T cells.     

Substrate Selection Influences Molecular Recognition in a Screen for Lymphoid Tyrosine Phosphatase Inhibitors

Assay design is an important variable that influences the outcome of an inhibitor screen. Here, we have investigated the hypothesis that protein tyrosine phosphatase inhibitors with improved biological activity could be identified from a screen by using a biologically relevant peptide substrate, rather than traditional phosphotyrosine mimetic substrates. A 2000‐member library of drugs and drug‐like compounds was screened for inhibitors of lymphoid tyrosine phosphatase (LYP) by using both a peptide substrate (Ac‐ARLIEDNE‐pCAP‐TAREG‐NH₂, peptide 1) and a small‐molecule phosphotyrosine mimetic substrate (difluoromethyl umbelliferyl phosphate, DiFMUP). The results demonstrate that compounds that inhibited enzyme activity on the peptide substrate had greater biological activity than compounds that only inhibited enzyme activity on DiFMUP. Finally, epigallocatechin‐3,5‐digallate was identified as the most potent inhibitor of lymphoid tyrosine phosphatase activity to date, with an IC₅₀ of 50 nM and significant activity in T‐cells. Molecular docking simulations provided a first model for binding of this potent inhibitor to LYP; this will constitute the platform for ongoing lead optimization efforts.     

Hybrid Organic‐Inorganic Membranes on Porous Supports by Size Exclusion and Thermal Sintering of Fluorescent Polyphenylsilsesquioxane Nanoparticles

Hybrid organic–inorganic membranes were prepared by size‐exclusion deposition and thermal sintering of fluorescent polyphenylsilsesquioxane nanoparticles on a ceramic support. Fluorescent polyphenylsilsesquioxane particles were prepared by a two‐step co‐polymerization of phenyltriethoxysilane with 0.1 mol‐% N‐(triethoxysilylpropyl)dansylamide. Because they were larger than the pores in the support, the particles formed a layer on top of the ceramic support that was sintered at 300 °C into a homogeneous, non‐porous membrane. Fluorescence of the modified polyphenylsilsesquioxane provided a valuable tool to monitor particle deposition and assist in characterization of the membranes.

     

ION-SELECTIVE POLYMER-SUPPORTED REAGENTS

ABSTRACT

The design and synthesis of polymer-supported reagents that can selectively complex targeted metal ions from multi-component solutions will continue to be an important area of research into the 21^st century. Environmental remediation and sensor technology are only two of a number of areas in which such polymers can be applied. This paper reviews the recent literature with an emphasis on the key ligands that have been immobilized in order to better understand where this research is heading in the near future.     

Influence of Experimental Setup and Plastic Deformation on the Shaft-Loaded Blister Test

In the shaft-loaded blister test (SLBT), plastic deformation often occurs at the contact area between the shaft tip and adhesive layer, leading to a larger displacement (blister height) than if the film was loaded elastically. As a consequence, incorporating the displacement variable into the analysis can result in misleading values of the applied strain energy-release rate, G. In this work, the influence of plastic yielding at the contact area on G of a thin film was investigated as a function of some common SLBT experimental variables, namely, substrate hole diameter, film thickness, and shaft-tip diameter. Test specimens consisted of plies of pressure-sensitive adhesive tape adhered to a rigid glass substrate. G was calculated from the following Equations: (1) load-based, (2) hybrid, (3) displacement-based, and (4) combination. Decreasing the film thickness, increasing the hole diameter, or decreasing the shaft-tip diameter lead to more plastic yielding at the contact area as well as to an increase in blister height. The increased blister height resulting from plastic deformation leads to disagreement among the values of G calculated from the different Equations when the displacement variable was included in the calculation. However, the load-based equation, which does not include the displacement, was determined to be independent of plastic yielding and the “correct” equation for calculating G. In addition, the film tensile rigidity (Eh) was calculated using an experimental compliance calibration. The effects of film thickness on the mechanical behavior of the film (bending plate vs. stretching membrane) as well as methods to determine the displacement resulting from plastic deformation are also discussed.     

Alterations in Serum Polyunsaturated Fatty Acids and Eicosanoids in Patients with Mild to Moderate Chronic Obstructive Pulmonary Disease (COPD)

Smoking is a major risk factor for several diseases including chronic obstructive pulmonary disease (COPD). To better understand the systemic effects of cigarette smoke exposure and mild to moderate COPD—and to support future biomarker development—we profiled the serum lipidomes of healthy smokers, smokers with mild to moderate COPD (GOLD stages 1 and 2), former smokers, and never-smokers (n = 40 per group) (ClinicalTrials.gov registration: {"type":"clinical-trial","attrs":{"text":"NCT01780298","term_id":"NCT01780298"}}NCT01780298). Serum lipidome profiling was conducted with untargeted and targeted mass spectrometry-based lipidomics. Guided by weighted lipid co-expression network analysis, we identified three main trends comparing smokers, especially those with COPD, with non-smokers: a general increase in glycero(phospho)lipids, including triglycerols; changes in fatty acid desaturation (decrease in ω-3 polyunsaturated fatty acids, and an increase in monounsaturated fatty acids); and an imbalance in eicosanoids (increase in 11,12- and 14,15-DHETs (dihydroxyeicosatrienoic acids), and a decrease in 9- and 13-HODEs (hydroxyoctadecadienoic acids)). The lipidome profiles supported classification of study subjects as smokers or non-smokers, but were not sufficient to distinguish between smokers with and without COPD. Overall, our study yielded further insights into the complex interplay between smoke exposure, lung disease, and systemic alterations in serum lipid profiles.     

Kinetics of Isothermal Crystallization of Hydrogenated Castor Oil-in-Water Emulsions

Kinetics of isothermal crystallization of hydrogenated castor oil in water emulsions exhibiting multiple crystal morphologies have been studied experimentally by DSC and polarized light microscopy. The induction time of nucleation increases with the increase of the isothermal temperature under which crystallization occurred. Crystal growth has been observed by microscopy showing that both crystal morphologies, fibers and rosettes, grow linearly at the initial stage of crystallization and then slow down to reach a plateau value. The Avrami model, which has been widely used in kinetics studies of triacylglycerol systems, was employed to fit experimental results at different isothermal temperatures. It was found that experimental trends could be captured by introducing the volume fraction of each type of morphology into three-dimensional and one-dimensional full Avrami models.