Characterization of recombinant human serum albumin using matrix-assisted laser desorption ionization time-of-flight mass spectrometry

Chromatographically purified recombinant human serum albumin (rHSA), produced in genetically transformed yeast cells, was characterized using matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) MS techniques. The molecular mass of the intact protein was determined to be 66671, in good agreement with that of purified HSA which was used as a standard. The identity of rHSA to its natural counterpart was established with high precision using peptide mass fingerprinting of tryptic peptides. Partial amino acid sequence data for rHSA were obtained using Ettan CAF MALDI Sequencing Kit and post-source decay on the tryptic peptides. The results achieved provide strong evidence that MALDI-TOF-MS is an important analytical technique for characterising gene products and for establishing the identity and bio-compatibility of recombinant proteins relative to their natural counterparts.     

Trace LC/MS/MS quantitation of 17β‐estradiol as a biomarker for selective estrogen receptor modulator activity in the rat brain

A sensitive LC/MS/MS method has been developed by derivatization of 17β‐estradiol (E2) with dansyl chloride to quantitate 17β‐E2 in female rat serum. The use of E2‐d₅ minimized interferences from endogenous 17β‐E2 in order to achieve a limit of quantitation (LOQ) of 2.5 pg/ml using 150 µl of female rat serum. The recovery of the dansyl derivative was 95% or greater in quality control samples. The intra and interday assay precision was better than 8.2 and 6.2%, respectively, with accuracies ranging from 97 to 101% in the quality control samples. The assay was used for the quantitation of serum E2 as a biomarker for the estrogen receptor (ER) antagonist activity of small molecule SERMs (selective estrogen receptor modulators) in the female rat brain. The study revealed that a statistically significant upregulation of serum 17β‐E2 occurred for rats dosed with SERMs that are known to penetrate the brain and disrupt the hypothalamic‐pituitary‐ovarian (HPO) axis. Variations in 17β‐E2 in ascending dose studies also correlated with the corresponding trends in CYP17a1 levels, an mRNA biomarker for ovarian hyperstimulation. This biomarker assay has provided a useful screen for medicinal chemistry optimization to produce SERMs that do not interfere with negative feedback of estrogens on the brain and for biological hypothesis testing. Copyright © 2009 John Wiley & Sons, Ltd.     

Synchrotron radiation of charged particles passing through the boundary between two media

The radiation of charged particles moving in a circle perpendicular to the boundary between two media is considered.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 51–57, May, 1977.     

Radiation of relativistic electrons in a magnetic undulator

Expressions are obtained for the spectral-angular characteristics of the radiation in two limiting cases: 1 and 1 ( is the angle of deflection of the electron in the field, and is the energy of the electron in units of mc²). It is shown that in the latter case the maximum of the radiation occurs at higher harmonics.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 88–91, October, 1973.In conclusion the authors thank Professor A. A. Sokolov for useful discussions.     

Lattice Boltzmann simulations of 2D laminar flows past two tandem cylinders

We apply the lattice Boltzmann equation (LBE) with multiple-relaxation-time (MRT) collision model to simulate laminar flows in two-dimensions (2D). In order to simulate flows in an unbounded domain with the LBE method, we need to address two issues: stretched non-uniform mesh and inflow and outflow boundary conditions. We use the interpolated grid stretching method to address the need of non-uniform mesh. We demonstrate that various inflow and outflow boundary conditions can be easily and consistently realized with the MRT-LBE. The MRT-LBE with non-uniform stretched grids is first validated with a number of test cases: the Poiseuille flow, the flow past a cylinder asymmetrically placed in a channel, and the flow past a cylinder in an unbounded domain. We use the LBE method to simulate the flow past two tandem cylinders in an unbounded domain with Re = 100. Our results agree well with existing ones. Through this work we demonstrate the effectiveness of the MRT-LBE method with grid stretching.