Ludmila Pavlova

Polymeric adsorbent for removing toxic proteins from blood of patients with kidney failure

A hypercrosslinked styrenic polymer with an enhanced proportion of mesopores in the range 2-20 nm has been developed. The principle of the synthesis consists of the suspension polymerization of divinylbenzene (or copolymerization of styrene with divinylbenzene) in the presence of a porogen that is a theta-solvent for polystyrene. On the scale of thermodynamic affinity, theta-solvents occupy a border position between good solvents and precipitating media for the growing polymer chains. In this case, microphase separation takes place during the final stages of the polymerization process. The polymer was shown to adsorb 93-98% of beta2-microglobulin from the blood or plasma of patients with chronic kidney failure. At the same time, large essential proteins, like albumin, are not removed to a significant extent, obviously, due to the size-exclusion effect and the difference in the hydrophobicity of the proteins. By replacing surface exposed pendant vinyl groups of the polymer with hydrophilic functional groups, the material was made hemocompatible, according to the standard battery of biocompatibility tests required by ISO 10993 guidelines. No adverse effects such as fever or hypotension were noted in dogs in direct hemoperfusion experiments with the polymer.

The next step from high-flux dialysis: Application of sorbent technology

The current foci of renal replacement therapy with dialysis are middle molecular weight toxins, consisting of small proteins, polypeptides and products of glycosylation and lipoxygenation. Conventional high-flux dialysis is not efficient at removing these molecules, explaining the increased interest in using sorbents to supplement dialysis techniques. Prototype biocompatible sorbents have been developed and investigated for middle molecule removal; these have been shown, in man, to remove β2-microglobulin, angiogenin, leptin, cytokines and other molecules, without reducing platelets and leukocytes. Extensive clinical studies are underway to demonstrate the clinical utility and safety of adding routinely a sorbent hemoperfusion device to hemodialysis.

Electron-probe X-ray microanalysis of individual particles of solid snow sediment with size factor correction.

A technique is proposed for X-ray electron-probe microanalysis (EPMA) of individual particles of solid snow sediment. Two sample preparation procedures were used to analyze the sediments. The PAP-method and the original bi-exponential model were used for matrix correction and the calculation of elemental composition. A method of calculating composition has been developed for approximately spherical individual particles, comparable in size with an area of X-ray generation. An analytical expression is proposed for determining the composition of these particles, taking account of their size. Including the size factor reduces the error of composition determination from 0.5-45 to 0.2-22% relative percent, for particles in the size range 1-3 microm.

Quality of determinations obtained from laboratory reference samples used in the calibration of X-ray electron probe microanalysis of silicate minerals

Abstract Nine simple minerals and oxides, traditionally used as laboratory reference samples in the electron probe microanalysis (EPMA) of silicate minerals, have been quantitatively evaluated. Three separate series of data, comprising the average concentration, standard deviation, relative standard deviation, confidence interval and the z -score of data quality, were calculated for 21 control samples derived from calibrations obtained from three sets of reference samples: (1) simple minerals; (2) oxides; and (3) certified glass reference materials. No systematic difference was observed between the concentrations obtained from these three calibration sets when analyzed results were compared to certified compositions. The relative standard deviations obtained for each element were smaller than target values for all determinations. The z -score values for all elements determined fell within acceptable limits (−2 z

A Selective Sorbent for Removing Bacterial Endotoxins from Blood

Synthetic ligands carrying a positive charge and capable of selective binding of bacterial endotoxins are covalently immobilized on surfaces of domestic hemosorbent Styrosorb-514 based on hypercrosslinked polystyrene. It is shown that the resulting sorbent aimed at treating sepsis exceeds imported specific hemosorbent in Toraymyxin™ columns in removing lipopolysaccharides, and can be used in domestically-produced Desepta columns.

Use of hypercrosslinked polystyrenes for removing iron complex salts and organic impurities from sodium thiocyanate solution in production of polyacrylonitrile fiber

The main organic impurities in concentrated solutions of sodium thiocyanate in different steps of production of polyacrylonitrile fiber were identified, and the possibility of their efficient removal simultaneously with iron salts by commercial sorbents of neutral hypercrosslinked polystyrene type was demonstrated.

Increasing selective bilirubin removal by hypercross-linked polystyrene hemosorbents

A high efficiency of indirect bilirubin removal from systems modelling blood plasma by polymers of various structures and, most importantly, by hemocompatible hypercross-linked polystyrenes such as Styrosorb is demonstrated. Approaches to increasing the selectivity of hypercross-linked polystyrenes for the removal of bilirubin from biological fluids with a high serum albumin content were found, making them promising materials for the manufacture of hemosorption columns effective for hepatitis therapy and other conditions caused by a high bilirubin content in the blood plasma.

Synthesis and sorption ability of telogenated hyper-cross-linked polydivinylbenzene networks

Synthesis and properties of hyper-cross-linked polymer networks prepared by radical polymerization of commercial divinylbenzene in oxylene, a good solvent and a powerful telogen, are reported. The permeability of hyper-cross-linked networks is evaluated by adsorption of bioactive molecules significantly differing in size. High sorption capacity for Cephalosporin C makes the polymers prepared promising for pharmacology and biotechnology.

On the oscillatory character of the sorption of amino acids on cationites

The kinetics of the absorption of D,L-β-phenyl-α-alanine and L-tryptophan by KU-2 × 8 sulfocationite was studied by spectrophotometry, dilatometry, and microscopy. Contrary to the literature data, the oscillatory character of absorption was not observed.

Development of X-Ray Electron Probe Microanalysis in Siberia

This paper describes the contribution of Siberian researchers to the development of X-ray electron probe microanalysis (EPMA) in 1969–2007. It is devoted to the 70th birthday of Valerii Petrovich Afonin (September 24, 1938–May 15, 1995).