Assessing the instability of the isoelectric focusing patterns of erythropoietin in urine

IEF can be used to differentiate human urinary erythropoietin (uEPO), recombinant human erythropoietin or epoetin (rEPO) and darbepoetin (novel erythropoiesis stimulating protein (NESP)). This is the basis of the method currently used to detect misuse of rEPO and NESP by elite athletes. Recently, an unknown activity has been attributed to some urine samples (denominated 'unstable' urine by the World Anti-Doping Agency; WADA). This activity has shown to give rise to artefactual profiles for both rEPO and NESP when incubated with such urine and, thus, raised concerns with respect to doping control. We have evaluated which charges produce the characteristic IEF profiles of uEPO, rEPO and NESP and how these profiles respond to distinct enzymatic reactions. From sialidase digestions it became evident that only uEPO contains charges different from sialic acid, and a comparison of all substances after complete de-N-glycosylation localized these charges in the carbohydrate moiety. Partial desialylation, or digestion with arylsulfatase from Helix pomatia yielded profiles for recombinants species similar to those observed for unstable urine samples. The contributions from our studies to the anti-doping problem include: (i) protocols that may corroborate the potential misuse of rEPO or NESP based on the particular enzymatic activity of an arylsulfatase preparation, or a broad-specificity sialidase; (ii) assurance that the instability observed in some urine samples may only result from false-negatives, but not from false-positive testing; and (iii) a simple remedy to prevent an unstable urine from altering the IEF profile by adding selective competitive substrates.     

GC-MS Study of Mono- and Bishaloethylphosphonates Related to Schedule 2.B.04 of the Chemical Weapons Convention: The Discovery of a New Intramolecular Halogen Transfer

A new class of compounds, mono- and bis-haloethylphosphonates (HAPs and bisHAPs, respectively), listed in Schedule 2.B.04 of the Chemical Weapons Convention (CWC), has been synthesized and studied by GC-MS with two aims. First, to improve the identification of this type of chemicals by the Organization for the Prohibition of Chemical Weapons, (OPCW). Second, to study the synergistic effect of halogen and silicon atoms in molecules undergoing mass spectrometry. Fragmentation patterns of trimethylsilyl derivatives of HAPs were found to depend on the nature of the halogen atom; this was in agreement with DFT-calculations. The data suggest that a novel intramolecular halogen transfer takes place during the fragmentation process.

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Graphical Abstract ?

     

The canonical shrinking soliton associated to a Ricci flow

To every Ricci flow on a manifold ${\mathcal{M}}$ over a time interval ${I\subset\mathbb{R}_-}$ , we associate a shrinking Ricci soliton on the space–time ${\mathcal{M}\times I}$ . We relate properties of the original Ricci flow to properties of the new higher-dimensional Ricci flow equipped with its own time-parameter. This geometric construction was discovered by consideration of the theory of optimal transportation, and in particular the results of the second author Topping (J Reine Angew Math 636:93–122, 2009), and McCann and the second author (Am J Math 132:711–730, 2010); we briefly survey the link between these subjects.     

A comparative study of the luminescence characteristics of polymineral fine grains and coarse-grained K- and Na-rich feldspars

The IRSL and post-IR IRSL (pIRIR) signal characteristics of polymineral fine grains are investigated and compared with those of K- and Na-rich feldspar extracts. TL signal loss after IR and pIRIR stimulations occurs mainly at around 320 °C for polymineral and Na-feldspar samples and around 410 °C for K-feldspar samples, when a preheat temperature of 250 °C for 60 s is used. After preheating to a higher temperature (320 °C for 60 s) all samples show a TL reduction around 410 °C in the blue detection window. Pulse annealing experiments for IRSL and pIRIR signals for preheats between 320 °C and 500 °C indicate that the signal stabilities are similar among the different feldspar types, when a higher preheat temperature (>320 °C) is used. Thermal activation energies for IRSL and pIRIR signals are largest in K-feldspar and smallest in polymineral fine grains, in both blue and UV detection windows for both fast time-resolved (TR) and continuous wave (CW) signals. These results suggest that IRSL and pIRIR signals in polymineral fine grains originate mainly from Na-feldspar grains; these signals are less thermally stable than those from K-feldspar, but a more stable signal (presumably from K-feldspar grains) can be obtained using a higher preheat temperature.     

Asymmetric Hydrogenation of α,β‐Unsaturated Carboxylic Esters with Chiral Iridium N,P Ligand Complexes

Enantioselective conjugate reduction of a wide range of α,β‐unsaturated carboxylic esters was achieved using chiral Ir N,P complexes as hydrogenation catalysts. Depending on the substitution pattern of the substrate, different ligands perform best. α,β‐Unsaturated carboxylic esters substituted at the α position are less problematic substrates than originally anticipated and in some cases α‐substituted substrates actually reacted with higher enantioselectivity than their β‐substituted analogues. The resulting saturated esters with a stereogenic center in the α or β position were obtained in high enantiomeric purity.     

Stereoselective functionalization of pyrrolidinone moiety towards the synthesis of salinosporamide A

An important feature of the synthesis of salinosporamide A, a potent proteasome inhibitor, is the establishment of the quaternary stereocenter at C3. A new route has been developed based on the methylation of a functionalized pyrrolidinone. Direct methylation reaction led to the unwanted diastereomer; however, by means of a Corey–Chaykovsky reaction followed by LiAlH₄ epoxide opening, the desired alcohol was obtained. The pyrrolidinone was elaborated through a key allylation reaction between a tertiary allyltitanium reagent and an aldehyde bearing a spiroketal moiety in α-position.     

Synthesis of enantiomerically pure anti-1,2-diaryl and syn-1,2-alkylaryl vic-selenoamines

Phenylselenyl benzylcarbanion stabilized by an (S)-2-p-tolylsulfinyl group evolves in a highly stereoselective way in the reactions with (S)-N-(p-tolylsulfinyl)imines at -98 °C affording diastereomerically pure 1,2-selenoamino derivatives in good yields. The syn or anti relationship of the obtained compounds depends on the alkyl or aryl character of the imine. They are easily transformed into enantiomerically pure (1R,2S)-1-aryl[or (1S,2S)-1-alkyl]-2-(phenylseleno)-2-phenylethylamines by reaction with t-BuLi and subsequent methanolysis of the generated sulfinamide derivatives with TFA.