Whole Body Branched-Chain L-Amino Acid Oxidation in Overnight Fasted Human Subjects

Abstract

Catabolism of the natural branched-chain L-amino acids in overnight fasted healthy volunteers was comparatively studied by performing oral loading tests with 1-¹³C-labelled L-leucine, L-valine, and L-isoleucine (38 μmol x kg (body weight)^?1), respectively. On the basis of the ¹³CO₂ exhalation and the ¹³C-isotope enrichment in the plasma branched-chain compounds, whole body branched-chain L-amino acid oxidation rates were estimated applying a seven compartment model and non-linear regression analysis. Mean computed in vivo oxidation rates were in the order L-leucine ? L-valine > L-isoleucine and amounted to 0.32 ± 0.06, 0.22 ± 0.04, and 0.17 ± 0.05 μmol x (kg body wt.)^?1 x min^?1 (n = 5), respectively. The data are discussed with respect to current estimates of human branched-chain L-amino acid requirements.     

Nanostructured Copper Oxide on Silica–Zirconia Mixed Oxides by Chemical Implantation

A new route to chemical implantation of copper(II) N,N‐dialkylcarbamato complexes on silica and nanostructured silica–zirconia matrices and subsequent thermal treatment (see scheme) is an efficient method of functionalizing the oxide matrices with nanostructured CuO. The materials have been characterized thoroughly and the effect of selected experimental parameters on the grafting reaction was investigated.

     

Polymers of C1?C4 paraffin hydrocarbons from an RF discharge: Characterization and reactivity

The polymers deposited from mixtures of argon and the vapors of methane, ethane, propane, and n-butane subjected to excitation in a 30-MHz discharge have been analyzed by infrared absorption techniques and for elemental composition. The polymers show unsaturation, crosslinking, and branching. The stability of the polymers to atmospheric oxidation is discussed.     

Formation of an 6α, 14-epoxy-bridged isomorphinan,an unusual product from a substituted 6α,14-dihydroxymorphinan

During alkylation of 3-O-benzyl-6α-naltrexol ( 1 ) with large aralkyl halides like 2-bromomethylnaphthalene and 9-chloromethylanthracene under phase transfer catalysis conditions (potassium hydroxide, tetrabutylammonium bromide, methylene chloride), formation of a new 6α,14-epoxide-bridged isomorphinan ( 4 ) was noted. Chemical and spectral evidence, including nmr and mass spectral data, are presented to prove its structure. Its formation results from 6α-oxygen displacement of a 14-O-aralkyl ether intermediate under the phase transfer catalysis alkylation conditions.     

Oxazolidine formation in the attempted eschweiler-clarke reductive methylation of cis-3-aminobicyclo[2.2.2] octan-2-ol

Evidence is presented confirming the formation of N-methyl-cis-bicyclo[2.2.2]octyl[2,3-d]-oxazolidine as the product of Eschweiler-Clarke reductive alkylation of cis-3-amino-bicyclo-[2.2.2]octan-2-ol.     

The MPSim-Dock hierarchical docking algorithm: application to the eight trypsin inhibitor cocrystals

To help improve the accuracy of protein-ligand docking as a useful tool for drug discovery, we developed MPSim-Dock, which ensures a comprehensive sampling of diverse families of ligand conformations in the binding region followed by an enrichment of the good energy scoring families so that the energy scores of the sampled conformations can be reliably used to select the best conformation of the ligand. This combines elements of DOCK4.0 with molecular dynamics (MD) methods available in the software, MPSim. We test here the efficacy of MPSim-Dock to predict the 64 protein-ligand combinations formed by starting with eight trypsin cocrystals, and crossdocking the other seven ligands to each protein conformation. We consider this as a model for how well the method would work for one given target protein structure. Using as a criterion that the structures within 2 kcal/mol of the top scoring include a conformation within a coordinate root mean square (CRMS) of 1 A of the crystal structure, we find that 100% of the 64 cases are predicted correctly. This indicates that MPSim-Dock can be used reliably to identify strongly binding ligands, making it useful for virtual ligand screening.     

Studies of the Interaction of the Salicylideneserinatecopper(II) Complex with β-Cyclodextrin: Characterization and Reactivity of the Inclusion Compound

The compound formed by the copper-Schiff base complex salicylideneserinatecopper(II), [Cu(sal-ser)(H2O)], interacting with -cyclodextrin was prepared, and characterized in the solid state by infrared, UV-visible and EPR spectroscopies, X- ray diffraction, and thermoanalytical techniques. The catalytic activity of this compound, [Cu(sal-ser)CD], in the decomposition of hydrogen peroxide, and in the dismutation of superoxide radicals was also verified, in comparison with the reactivity of the free complex, in aqueous solution. In both cases, a decreasing in the reaction rate was observed for the CD-containing compound. The results of structural characterization, in addition to the substantial differences observed in the catalytic activities of the compounds, are indicative of partial insertion of the copper complex in the cavity of the oligosaccharide.     

Conductive plastics: comparing alternative nanotechnologies by performance and life cycle release probability

Nanocomposites can be considered safe during their life cycle as long as the nanofillers remain embedded in the matrix. Therefore, a possible release of nanofillers has to be assessed before commercialization. This report addresses possible life cycle release scenarios for carbon nanotubes (CNT), graphene, and carbon black (CB) from a thermoplastic polyurethane (TPU) matrix. The content of each nanofiller was adjusted to achieve the same conductivity level. The nanofillers reduced the rate of nanoscale releases during mechanical processing with decreasing release in the order neat TPU, TPU-CNT, TPU-graphene, and TPU-CB. Released fragments were dominated by the polymer matrix with embedded or surface-protruding nanofillers. During electron microscopy analysis, free CB was observed, however, there was no free CNT or graphene. Quantitatively, the presence of free nanofillers remained below the detection limit of <0.01% of generated dust. Further, both the production process and type of mechanical processing showed a significant impact with higher release rates for injection-molded compared to extruded and sanded compared to drilled materials. Due to its optimal performance for further development, extruded TPU-CNT was investigated in a combined, stepwise worst case scenario (mechanical processing after weathering). After weathering by simulated sunlight and rain, CNT were visible at the surface of the nanocomposite; after additional sanding, fragments showed protruding CNT, but free CNT were not detected. In summary, this preliminary exposure assessment showed no indication that recommended occupational exposure limits for carbonaceous nanomaterials can be exceeded during the life cycle of the specific TPU nanocomposites and conditions investigated in this study.