A new ultrafast and high-throughput mass spectrometric approach for the therapeutic drug monitoring of the multi-targeted anti-folate pemetrexed in plasma from lung cancer patients

An analytical assay has been developed and validated for ultrafast and high-throughput mass spectrometric determination of pemetrexed concentrations in plasma using matrix assisted laser desorption/ionization–triple quadrupole–tandem mass spectrometry. Patient plasma samples spiked with the internal standard methotrexate were measured by multiple reaction monitoring. The detection limit was 0.4 fmol/μL, lower limit of quantification was 0.9 fmol/μL, and upper limit of quantification was 60 fmol/μL, respectively. Overall observed pemetrexed concentrations in patient samples ranged between 8.7 (1.4) and 142.7 (20.3)?pmol/μL (SD). The newly developed mass spectrometric assay is applicable for (routine) therapeutic drug monitoring of pemetrexed concentrations in plasma from non-small cell lung cancer patients.     

The Shapley value for the probability game

The main goal of this paper is to introduce the probability game. On one hand, we analyze the Shapley value by providing an axiomatic characterization. We propose the so-called independent fairness property, meaning that for any two players, the player with larger individual value gets a larger portion of the total benefit. On the other, we use the Shapley value for studying the profitability of merging two agents.     

Raman spectroscopy of selected arsenates--implications for soil remediation

The contamination of soils with heavy metals such as As, Cr and Cu is of great importance; the remediation of such soils even more so. Arsenic compounds are prevalent in soils either through leaching of mine tailings, the use of Cu/Cr/As as a wood preservative or through the use of arsenic in cattle dips. The arsenic compounds in soils and leachates can be highly reactive and mobile, resulting in the formation of metal arsenate compounds. Of these compounds, one such set of minerals that can be formed is the vivianite arsenate minerals. Raman spectroscopy has been used to characterise the vivianite arsenates and to identify arsenic contaminants in a soil.     

Application of fluorescence polarization to enzyme assays and single nucleotide polymorphism genotyping: some recent developments

This article describes some recent developments in the field of fluorescence polarization (FP) as applied to enzyme assays and single nucleotide polymorphism (SNP) genotyping. First, we present our recent progress on the application of fluorescence polarization to high throughput screening (HTS). We show how the use of a 2-thiopyridinone-based, mixed disulfide biotinylation reagent can shorten the assay time of our recently reported kinase assay method based on thiophosphorylation and biotinylation from several hours to a few minutes. We also summarize our recent findings on a new approach for HTS of kinases, proteases and phosphatases based on the use of a cationic poly-amino acid such as polyarginine. We show how the careful selection of the polyarginine concentration and the ionic strength of the solution during the FP measurement allow one to expand the range of substrates that can be assayed. Both of these methods are valuable additions to the existing techniques for HTS. Most importantly, both of these methods can be applied to the assay of kinases without the need for any antibodies. In the area of genomics, we present some results from our studies on a new single nucleotide polymorphism typing approach based on the polymerase catalyzed extension of 3' fluorescein labeled primers. Contrary to our initial expectations, we observed that the enzymatic extension of these primers results in a significant decrease of the fluorescence polarization value. Possible explanations of this phenomenon are discussed.     

Selectivity and efficiency enhancement of supercritical fluid extraction by application of reactive additives. I. The analysis of calcium montanate using citric acid as a complexing agent

It has been demonstrated that calcium montanate (a mixture of aliphatic hydrocarbons, fatty acid esters of C₂₈–C₃₂ acids, the calcium salts of these fatty acids, and the acids themselves) can be selectively extracted with supercritical fluids. By use of carbon dioxide, carbon dioxide containing 10% methanol, and carbon dioxide containing 10% methanol and citric acid (as a further additive), the various compound classes could be isolated with high selectivity. The addition of citric acid results in the complexation of Ca²⁺ and the simultaneous formation of the free fatty acids, which are soluble in the extractant.     

Raman spectroscopy of the mineral rhodonite

The mineral rhodonite an orthosilicate has been characterised by Raman spectroscopy. The Raman spectra of three rhodonites from Broken Hill, Pachapaqui and Franklin were compared and found to be similar. The spectra are characterised by an intense band at around 1000 cm(-1) assigned to the nu(1) symmetric stretching mode and three bands at 989, 974 and 936 cm(-1) assigned to the nu(3) antisymmetric stretching modes of the SiO(4) units. An intense band at around 667 cm(-1) was assigned to the nu(4) bending mode and showed additional bands exhibiting loss of degeneracy of the SiO(4) units. The low wave number region of rhodonite is complex. A strong band at 421.9 cm(-1) is attributed to the nu(2) bending mode. The spectra of the three rhodonite mineral samples are similar but subtle differences are observed. It is proposed that these differences depend upon the cationic substitution of Mn by Ca and/or Fe(2+) and Mg.     

Quantum phase transition in spin glasses with multi-spin interactions

We examine the phase diagram of the p-interaction spin glass model in a transverse field. We consider a spherical version of the model and compare with results obtained in the Ising case. The analysis of the spherical model, with and without quantization, reveals a phase diagram very similar to that obtained in the Ising case. In particular, using the static approximation, reentrance is observed at low temperatures in both the quantum spherical and Ising models. This is an artifact of the approximation and disappears when the imaginary time dependence of the order parameter is taken into account. The resulting phase diagram is checked by accurate numerical investigation of the phase boundaries.