Determination of phosphonoformic acid in human plasma and urine by high-performance liquid chromatography with electrochemical detection

Trisodium phosphonoformate (foscarnet) is used in the treatment of cytomegalovirus infections in immunocompromised patients, such as bone marrow and renal transplant recipients, as well as patients with the acquired immune deficiency syndrome. A simple high-performance liquid chromatographic assay is described using an electrochemical detector. The method is accurate, precise and reproducible. Hydrochlorothiazide is used as the internal standard. This assay allows measurement of foscarnet in biological fluids at concentrations as low as 33 microM. This method is being used for the analysis of samples in clinical trials and is important in the evaluation of the pharmacokinetic disposition of the drug.     

Contribution of ionically immobilized bovine serum albumin to the retention of enantiomers.

The retention of the enantiomers of mandelic acid and N-benzoylalanine was studied on columns prepared by immobilizing bovine serum albumin (BSA) on an anion exchanger. The amount of BSA fixed on the column is easy to adjust and measure. The adsorption isotherms were determined. For each enantiomer, the isotherm is well accounted for by a bi-Langmuir equation. One term of the isotherm (which is the same for both enantiomers) corresponds to non-selective interactions and the other term to the chiral selective interactions. The column saturation capacity of this second term is 8% larger for the less strongly retained enantiomer. This saturation capacity corresponds approximately to one enantiomer molecule adsorbed for five BSA molecules immobilized. This result is in agreement with the assumption of the hydrophobic cavity of BSA being the chiral selective site.     

An extended chain structure formed by covalently linking polyoxovanadate cages with tetrahedral six rings

The compound Cs10.5[(V16O40)(Si4.5V1.5O10)].3.5H2O is the first example of an extended structure in which a polyoxometallate anion is linked by an extended tetrahedral unit.     

Mode of sugar phosphorylation inClostridium thermocellum

Fungi were screened for important industrial enzymes produced from industrial chips and sawdust of laurel (Louro inamui, Ocotea cymbarum) and cedar (Cedro, Cedrella odorata). Seven hyphomycetes and one zygomycete were isolated and characterized. Two different media for testing the enzymatic activities were used. In general, in potato dextrose (1%) medium (M-3) a preponderancy of ligninolytic over cellulolytic enzymes was observed. In potato infusion-sawdust wood (1%) medium (M-4) the cellulolytic, xylanolytic, and lipolytic enzymes were efficiently induced. Significant modulation of enzyme production by the carbon source was found in the extracted fungi from self-heated industrial chips piles of cedar and laurel trees at the Amazonian region.     

Selective ordering of surfactant modified gold nanoparticles in a diblock copolymer

Ordered aggregation of thiol-passivated Au nanoparticles in a diblock copolymer polystyrene-b-poly(methyl methacrylate) has been observed. The morphology of the diblock copolymer/Au-nanocomposite was dependent on the composition of the thiol modifier. For the thiol modifier that does not preferentially interact with one of the blocks, a perpendicular (relative to the substrate) lamellar morphology is maintained. However, for a thiol with a surfactant structure similar to one of the blocks, we observed a parallel lamellar morphology and speculate that the nanoparticles have localized at the microdomain interface. These conclusions are based on transmission electron microscopy, angle-dependent X-ray photoelectron microscopy and tensiometry. These results are consistent with theoretical predictions on the hybrid systems composed of block copolymers and nanoparticles.