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At least 595 records · Page 33Linked to original sources
PubMed1985

Preparation and evaluation of microencapsulated and coated ion-exchange resin beads containing theophylline.

Anion-exchange resin beads in the theophylline form were prepared and coated with paraffin or encapsulated with ethylcellulose by various methods; one of these products was subsequently coated with paraffin in order to achieve a wide range of release rates and patterns of release. The various products were subjected to rate studies, and it was found that the patterns of release and the rates could be controlled by the cross-linking of the resin and the coating procedures used. A medium and almost constant rate of release was obtained by using ethylcellulose microencapsulation, a coating of hard paraffin, or a combination of both. The amount of coating and the total amount of drug released was also determined.

Chemical Phenomena↗
PubMed1971

Clostridium perfringens. I. Sporulation in a biphasic glucose-ion-exchange resin medium.

A biphasic culture medium suitable for cultivation and sporulation of Clostridium perfringens, C. botulinum, and C. sporogenes was devised. The medium designed for use in a disposable, compartmented, plastic film container contained peptones, yeast extract, minerals, an anion exchange resin, and glucose in 4% agar as the solid phase and (NH(4))(2)SO(4) and 0.1% agar as the liquid phase. With the biphasic system, it was not necessary to use active cultures as inocula. Growth was at least equal to that obtained in conventional media, and spore production of 9 out of 12 strains of C. perfringens equalled or usually exceeded that of conventional media.

Agar↗
PubMed1995

Preparative-scale amino acid separation by thermal parametric pumping on an ion-exchange resin.

Thermal parametric pumping was experimentally investigated for the concentration and separation of amino acids. Previous theories of parametric pumping were improved by taking into account dissociation equilibria in the liquid phase. Experiments were carried out with a mixture of glutamic acid, aspartic acid, serine and threonine in a highly acidic solution (HCl). A multi-component equilibrium model was mainly used to simulate the experimental results and to investigate the effect of chloride concentration over a wide range. It is shown that it is always possible to concentrate the amino acids and to separate some of them under certain conditions.

Amino Acids↗
PubMed1976

Biological ion exchanger resins; IX. Isolation and partial identification of a potassium sensitive contractile-like protein from E. coli.

A protein fraction with actin-like characteristics has been isolated from E. coli. The fraction (referred to as A-L fraction) undergoes reversible increases in molecular weight under the same catalytic conditions that polymerize actin, exhibits a distinct peak on SDS electrophoresis at the characteristic molecular weight for actin, depends primarily on potassium for its polymerization, and is not "polymerized" by sodium. A-L fraction in the monomeric form was eluted in the void volume of a Sepharose 6B column, suggesting a large Stoke's radius and a molecular weight in excess of 400,000. The fraction contained 30% RNA by weight that proved refractory to experimental efforts at removal.

Actins↗
PubMed1976

Actin-like properties from Escherichia coli: concept of cytotonus as the missing link between cell metabolism and the biological ion-exchange resin.

A protein fraction (A-L fraction) with characteristics reminiscent of muscle actin has been isolated from Escherichia coli. The A-L fraction undergoes reversible aggregation under the same conditions in which actin is polymerized and depends primarily on potassium for its polymerization. This fraction, upon electrophoresis on acrylamide gels in the presence of sodium dodecyl sulfate, exhibits a distinct peak at the characteristic molecular weight of 45,000. Passage of skeletal muscle myosin through the A-L fraction specifically removes this 45,000-molecular weight peak. Examination of the myosin by sodium dodecyl sulfate electrophoresis after the passage reveals a new band at the proper molecular weight. The A-L fraction from wild-type E. coli is compared with the protein from a potassium transport mutant. Important catalytic differences exist between the A-L fractions of the two strains. The A-L fraction from the mutant fails to polymerize in low-K media in the K+ concentration range in which the mutant fails to take up to K+. In low-K+ media, the parent strain accumulates potassium and the A-L fraction from this organism polymerizes. The cell swelling reaction of both strains has been studied. Parent cells swell during low-K+ uptake, whereas the mutant does not. It is construed from this that the differences in the characterization of the A-L fraction relative to that of the wild type are related to the loss of cell swelling in the mutant and hence to the loss in alkali cation selectivity. The possible role of contractile proteins in biological ion exchange is discussed.

Actins↗
PubMed1983

Synthesis and quality control testing of 32P labeled ion exchange resin microspheres for radiation therapy of hepatic neoplasms.

Commercial cation exchange resin beads (200--400 mesh) are separated into narrow particle size ranges by sieving and differential sedimentation. These microspheres are converted into the chromic form by reaction with Cr(NO2)3, labeled with 20 mCi 32P phosphate by exchange at pH 2--4, and converted to a stable product at pH 9. Chemical stability ahd biological behavior of these microspheres suspended in physiological saline is measured before administration through a hepatic artery catheter for radiation therapy of the liver and hepatic neoplasms.

Catheterization↗
PubMed1979

Removal of bilirubin by hemoperfusion with ion exchange resins.

Removal of bilirubin by hemoperfusion with macroporous resins is suggested to replace exchange transfusion of blood from jaundiced infants. Anion exchangers tested for BIL binding rate and the effects of various system parameters, i.e. particle size, temperature, bed volume, fluid flow rate and particle porosity are reported. The dissociation equilibrium constant K of the BIL-ALB (albumin) complex was determined from the equilibrium adsorption isotherms data, at different ALB concentrations. Increasing ALB concentration decreased the BIL adsorption rate. For a given ALB concentration, the ratio of unbound to total BIL was constant and the initial BIL adsorption rate was independent of total BIL concentration.

Adsorption↗
PubMed2005

Sorption and desorption of flumioxazin to soil, clay minerals and ion-exchange resin.

Flumioxazin adsorption kinetics were described using a Greenville sandy clay loam soil. Adsorption kinetics experiments showed that 72% of total herbicide was absorbed after 1 h of continuous shaking and continued to increase to 78% after 72 h. Flumioxazin adsorption was then tested on seven agriculturally important soils throughout the southern USA. Adsorption isotherms for all soils had K(f) (Freundlich distribution coefficient) values that ranged from 8.8 to 0.4, with many near 1.5. Soil organic matter content was the parameter most highly correlated with flumioxazin adsorption (r(2) = 0.95, P < 0.001). Sorption to clay minerals had K(f) values ranging from 50 for bentonite to 4.7 for kaolinite. However, normalizing K(f) for sorbent surface area revealed that aluminum hydroxide (gibbsite) possessed the greatest flumioxazin sorption per unit area. Sorption to anionic exchange resin (K(f) 676) was greater than cationic exchange resin (K(f) 42). Molecular model calculations were performed to elucidate why sorption was greater to anionic exchangers. These calculations indicated that a region of dense electronegativity exists on the 3-dione moiety of the molecule. This would lead to greater flumioxazin sorption by positively charged surface sites. Desorption isotherms from soil exhibited no effect of hysteresis. Desorption from clay minerals was very rapid and flumioxazin in solution was undetectable after three desorption steps. From these data it was concluded that flumioxazin can become readily available in soil solution with increase in soil water content.

Adsorption↗