Phenotyping apolipoprotein E*3-leiden transgenic mice by two-dimensional polyacrylamide gel electrophoresis and mass spectrometric identification

Apolipoprotein E (ApoE) plays an important role in cholesterol and triglyceride metabolism, being one of the major structural components of chylomicrons and very low density lipoprotein (VLDL) remnants. ApoE functions as a ligand in the receptor-mediated uptake of these remnants from the blood by the liver. A variant form of ApoE, apolipoprotein E*3-Leiden, shows reduced affinity for the low density lipoprotein (LDL) receptor, and results in the dominant expression of type III hyperlipoproteinemia. Two-dimensional electrophoresis (2-DE) has been used to characterise protein expression in serum samples from control and transgenic mice expressing the human ApoE*3-Leiden mutation, fed a cholesterol-rich diet, and transgenic mice fed a normal diet. For the identification of proteins, single silver-stained spots were excised from the 2-DE gels and subjected to in-gel enzymatic digestion. Extracted peptides were analysed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). This proteomic approach has enabled the ApoE*3-Leiden variant to be positioned in a 2-DE separation of serum proteins, and has identified changes in the expression of haptoglobin, indicating that this protein may provide a marker for the potential onset of atherosclerosis.     

High-performance liquid chromatographic separation of the enantiomers of hydroxychloroquine and its major metabolites in biological fluids using an alpha 1-acid glycoprotein stationary phase.

An enantioselective two-stage off-line assay has been developed for the analysis of hydroxychloroquine and its three major metabolites in biological fluids. The first non-stereoselective stage of the assay (PRP-1 column) separates and quantitates parent drug and metabolites. Fractions containing hydroxychloroquine and each of the metabolites are collected manually, evaporated, reconstituted in mobile phase and re-injected onto an alpha 1-acid glycoprotein column to separate and determine proportions of individual enantiomers. Preliminary results from patients samples indicate that the disposition of hydroxychloroquine and its major metabolites is enantioselective. p6     

Derivation of a modified paraxial formalism for two-dimensional trajectories in electron and ion sources of non-simple geometries

A modified paraxial formalism has been developed which describes two-dimensional charged particle beam dynamics in electron and ion sources with pointed or needle-type geometries. A Hamiltonian formalism, and a more exact treatment of energy conservation is used to derive the modified paraxial equation for two-dimensional trajectories in systems with axially symmetric prolate-spheroidal beams. Calculations have been done for a gallium field emission liquid metal ion source modeled by a hyperboloid of revolution and planar extractor. Two important conclusions emerge from these calculations: i) The dominant effect of space-charge, for source geometries with small radii of curvature, occurs in the region close to the apex (<0.05 n) and ii) beam divergence has a strong dependence on geometry. This latter effect is a consequence of large two-dimensional field gradients near the apex of sources with needle-type or pointed geometry.This work was supported in part by the Division of Materials Research, National Science Foundation, Grant No. DMR-8108829     

Some results on the behavior and estimation of the fractal dimensions of distributions on attractors

The strong interest in recent years in analyzing chaotic dynamical systems according to their asymptotic behavior has led to various definitions of fractal dimension and corresponding methods of statistical estimation. In this paper we first provide a rigorous mathematical framework for the study of dimension, focusing on pointwise dimension(x) and the generalized Renyi dimensionsD(q), and give a rigorous proof of inequalities first derived by Grassberger and Procaccia and Hentschel and Procaccia. We then specialize to the problem of statistical estimation of the correlation dimension and information dimension. It has been recognized for some time that the error estimates accompanying the usual procedures (which generally involve least squares methods and nearest neighbor calculations) grossly underestimate the true statistical error involved. In least squares analyses of and we identify sources of error not previously discussed in the literature and address the problem of obtaining accurate error estimates. We then develop an estimation procedure for which corrects for an important bias term (the local measure density) and provides confidence intervals for. The general applicability of this method is illustrated with various numerical examples.     

Aqueous synthesis of alkanethiolate-protected Ag nanoparticles using Bunte salts

The one-pot synthesis of monolayer-protected metal nanoparticles derived from sodium S-dodecylthiosulfate (Bunte salt) in aqueous solution is described. Silver nanoparticles, which were produced by the borohydride reduction of silver nitrate in H2O, were stabilized by the adsorption of S-dodecylthiosulfate followed by the removal of the SO3- moiety. Temporary stabilization of silver sols by the adsorption of borohydride and borate prevented aggregation of silver nanoparticles in H2O. The syntheses of other metal nanoparticles, including gold, copper, and palladium particles in H2O, were less successful. Gold and copper particles were completely aggregated and precipitated out immediately after the addition of NaBH4, yielding only insoluble clusters. Stable and soluble palladium nanoparticle could be prepared, but the presence of Pd-thiolate complex was also observed. These nanoparticles were characterized using 1H NMR, UV-vis spectroscopy, FT-IR spectroscopy, and transmission electron microscopy.     

Proposed Mechanism for the Antitrypanosomal Activity of Quercetin and Myricetin Isolated from Hypericum afrum Lam.: Phytochemistry,In Vitro Testing and Modeling Studies

The in vitro activity of L. donovani (promastigotes, axenic amastigotes and intracellular amastigotes in THP1 cells) and T. brucei, from the fractions obtained from the hydroalcoholic extract of the aerial part of Hypericum afrum and the isolated compounds, has been evaluated. The chloroform, ethyl acetate and n-butanol extracts showed significant antitrypanosomal activity towards T. brucei, with IC₅₀ values of 12.35, 13.53 and 12.93 µg/mL and with IC₉₀ values of 14.94, 19.31 and 18.67 µg/mL, respectively. The phytochemical investigation of the fractions led to the isolation and identification of quercetin (1), myricitrin (2), biapigenin (3), myricetin (4), hyperoside (5), myricetin-3-O-β-d-galactopyranoside (6) and myricetin-3’-O-β-d-glucopyranoside (7). Myricetin-3’-O-β-d-glucopyranoside (7) has been isolated for the first time from this genus. The chemical structures were elucidated by using comprehensive one- and two-dimensional nuclear magnetic resonance (1D and 2D NMR) spectroscopic data, as well as high-resolution electrospray ionization mass spectrometry (HR-ESI–MS). These compounds have also been evaluated for their antiprotozoal activity. Quercetin (1) and myricetin (4) showed noteworthy activity against T. brucei, with IC₅₀ and IC₉₀ values of 7.52 and 5.71 µM, and 9.76 and 7.97 µM, respectively. The T. brucei hexokinase (TbHK1) enzyme was further explored as a potential target of quercetin and myricetin, using molecular modeling studies. This proposed mechanism assists in the exploration of new candidates for novel antitrypanosomal drugs.