PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “ION EXCHANGE RESINS”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 901 records · Page 50Linked to original sources
PubMedDate not supplied

[Method of determination of the number of enteroviruses present in natural waters].

The effectiveness of concentratin of enteroviruses present in water by adsorption on membrane filters, ion-exchange resin AB-17-8 and bentonite was compared with set concentrations of virus in water (0.05-0.1-0.5-2.5 and 12.5 PFU/ml). The effectiveness of concentration was shown to depend upon the initial dose of virus present in water. With virus adsorption on membrane filters and ionexchange resin the effectiveness of concentration was the higher (100 and 74%) the lower the virus dose in water (0.05 PFU/ml), with bentonite the effectiveness was the higher (60%) the higher virus dose in water (12.5 PFU/ml). A method is proposed for sufficiently accurate determination of virus concentration in water by simultaneous and parallel removal of virus particles in two ways one of which gives a maximum effect with low doses of virus and the other with large doses.

Adsorption↗
PubMed1970

Two toxins from a poisonous sample of mussels Mytilus edulis.

1. A crude preparation of toxin was extracted from a sample of mussels Mytilus edulis, part of a batch responsible for many cases of paralytic shellfish poisoning.2. The crude extract was partially purified by absorption on sodium Amberlite ion-exchange resin. Two toxins were recovered by elution from the Amberlite, and purified further by gel filtration.3. One toxin closely resembled saxitoxin in its behaviour on Amberlite and in its biological effects.4. The other toxin behaved quite differently on the Amberlite. Its molecule was small, comparable in size with saxitoxin. It was not tetrodotoxin. Its biological effects were similar, but not identical, to those of saxitoxin: it paralysed muscular contraction and inhibited conduction along nerves; it caused death of experimental animals by producing a peripheral paralysis of respiration; it did not depolarize the membrane of frog skeletal muscle fibres, but acted by preventing a stimulus from initiating a conducted action potential.5. The biological effects of the second toxin suggest that, like saxitoxin and tetrodotoxin, it is an inhibitor of inward sodium ion movement through electrically excitable membranes.

Animals↗
PubMed1975

A 82Sr-82Rb isotope generator for use in nuclear medicine.

An improved 82Sr-82Rb generator system, based on the complexing ion-exchange resin Chelex-100, has been developed. Columns of this material can be easily and rapidly milked, and the rubidium-strontium separation factor for a fresh generator under the experimental conditions studied was found to be greater than 10-7. Approximately 80% of the 82Rb present can be delivered in a 15-ml volume of aqueous 0.2 M NH4Cl solution. After more than 6 liters of eluant had passed through the generator, the rubidium-strontium separation factor was still observed to greater than 10-5 and no unusual strontium breakthrough behavior was seen in the system over nearly three 82Sr half-lives.

Ion Exchange Resins↗
PubMed2005

Selective removal of arsenate from drinking water using a polymeric ligand exchanger.

The new maximum contaminant level (MCL) of 10 microg/L for arsenic in the US drinking water will take effect on January 22, 2006. The compliance cost is estimated to be approximately dollar 600 million per year using current treatment technologies. This research aims to develop an innovative ion exchange process that may help water utilities comply with the new MCL in a more cost-effective manner. A polymeric ligand exchanger (PLE) was prepared by loading Cu2+ to a commercially available chelating ion exchange resin. Results from batch and column experiments indicated that the PLE offered unusually high selectivity for arsenate over other ubiquitous anions such as sulfate, bicarbonate and chloride. The average binary arsenate/sulfate separation factor for the PLE was determined to be 12, which were over two orders of magnitude greater than that (0.1-0.2) for commercial strong-base anion (SBA) exchangers. Because of the enhanced arsenate selectivity, the PLE was able to treat approximately 10 times more bed volumes (BVs) of water than commonly used SBA resins. The PLE can operate optimally in the neutral pH range (6.0-8.0). The exhausted PLE can be regenerated highly efficiently. More than 95% arsenate capacity can be recovered using approximately 22 BVs of 4% (w/w) NaCl at pH 9.1, and the regenerated PLE can be reused without any capacity drop. Upon treatment using FeCl3, the spent brine was recovered and reused for regeneration, which may cut down the regenerant need and reduces the volume of process waste residuals. The PLE can be used as a highly selective and reusable sorbent for removal of arsenate from drinking water.

Arsenates↗
PubMed1989

Hollow fibers as an oral sustained-release delivery system.

Phenylpropanolamine (PPA) bound to ion-exchange resin was encapsulated in hollow fibers made of segmented polyurethane. This system was examined as an oral sustained-release delivery system. The fibers were spun by the phase inversion process and cut into different aspect ratios (length/diameter). The U.S.P. basket dissolution method was used to evaluate the in vitro drug release kinetics and the effect of the aspect ratio on the release. For in vivo evaluation, selected fibers were orally administered to dogs in gelatin capsules. The fiber delivery system provided a sustained-release profile of plasma PPA and a longer terminal half-life when compared to an oral immediate-release formulation.

Administration, Oral↗
PubMed1986

Iodination of monoclonal antibodies for diagnosis and radiotherapy using a convenient one vial method.

We have developed a convenient system that can be used to iodinate monoclonal antibodies for diagnosis or therapy. A vial, previously coated with 1,3,4,6-tetrachloro-3a, 6a-diphenyl glycouril (iodogen), is used as a reaction vessel. Iodination and separation of bound and free iodide, using AG1-X8 ion exchange resin, are both accomplished in this vial. We found 90 +/- 4% of the iodide which was added was incorporated, respectively, into each of four different monoclonal antibodies evaluated. Approximately 90% of labeled antibody was recovered in each case. The monoclonal antibody OC125 was labeled to specific activities up to 25 mCi/mg. Immunoreactivities of 82 +/- 2% using 125I and 66 +/- 5% using 131I were achieved. As the radioiodination is done in one sealed vial and takes less than 15 min, this procedure is safe and can be performed in any nuclear medicine laboratory. The final product, which is sterile and apyrogenic, is suitable for diagnostic and radiotherapeutic applications.

Antibodies, Monoclonal↗
PubMed1967

NMR evidence for complexing of Na+ in muscle, kidney, and brain, and by actomyosin. The relation of cellular complexing of Na+ to water structure and to transport kinetics.

The nuclear magnetic resonance (NMR) spectrum of Na(+) is suitable for qualitative and quantitative analysis of Na(+) in tissues. The width of the NMR spectrum is dependent upon the environment surrounding the individual Na(+) ion. NMR spectra of fresh muscle compared with spectra of the same samples after ashing show that approximately 70% of total muscle Na(+) gives no detectable NMR spectrum. This is probably due to complexation of Na(+) with macromolecules, which causes the NMR spectrum to be broadened beyond detection. A similar effect has been observed when Na(+) interacts with ion exchange resin. NMR also indicates that about 60% of Na(+) of kidney and brain is complexed. Destruction of cell structure of muscle by homogenization little alters the per cent complexing of Na(+). NMR studies show that Na(+) is complexed by actomyosin, which may be the molecular site of complexation of some Na(+) in muscle. The same studies indicate that the solubility of Na(+) in the interstitial water of actomyosin gel is markedly reduced compared with its solubility in liquid water, which suggests that the water in the gel is organized into an icelike state by the nearby actomyosin molecules. If a major fraction of intracellular Na(+) exists in a complexed state, then major revisions in most theoretical treatments of equilibria, diffusion, and transport of cellular Na(+) become appropriate.

Animals↗
PubMed2004

Ethanol production in immobilized-cell bioreactors from mixed sugar syrups and enzymatic hydrolysates of steam-exploded biomass.

We investigated ethanol production from mixed sugar syrups. Hydrolysates were prepared from enzymatic saccharification of steam-pretreated aspen chips. Syrups containing 45 g/L of glucose and 12 g/L of xylose were detoxified through two ion-exchange resins and then fermented with Pichia stipitis and Saccharomyces cerevisiae immobilized in Ca-alginate gel beads. Combinations of different gel fractions in the fermentation volume, amount of yeast cells, and ratios of P. stipitis vs S. cerevisiae within each bead were compared. In the best conditions, by using a total beads volume corresponding to 25% of the working volume, we obtained a yield of 0.39 g(ethanol)/g(initial sugars). This amount of gel entrapped an initial cell concentration of 6 x 1012cells/L with ratio of S. cerevisiae/P. stipitis of 0.25 g/g. Modified stirred-tank reactors were obtained either by adding marbles or by inserting a perforated metal cylinder, which reduced considerably the rupture of beads while visibly improving oxygenation of the medium.

Alginates↗
PubMed1977

Rapid chromatographic method to determine polyamines in urine and whole blood.

A procedure is described for the rapid determination of putrascine, spermine and spermidine in ruine and whole blood. The samples are hydrolyzed with barium hydroxide and are neutralized with sulfuric acid. The polyamines are concentrated and separated from amino acids on a small bed of ion-exchange resin that then serves to load the samples on a two-channel, automated ion-exchange chromatography apparatus. As many as 100 samples can be analyzed in a 24-h period. The method has been shown to be applicable to the analysis of urine and whole blood samples, but further development is needed for application to serum samples.

Autoanalysis↗
PubMed1976

Acute colitis in the renal allograft recipient.

Four renal allograft recipients with evidence of ischemic damage to the colon are presented and compared with 11 cases from 5 major series. Similarities in the patients included: deterioration of renal function, multiple immunosuppressive and antibiotic regimens, the use of cadaver renal allografts, and diagnostic and therapeutic measures requiring frequent enemas with barium and ion-exchange resins. Two of our patients underwent surgery for the removal of segments of necrotic colon after several weeks of fever and abdominal pain initially attributed to either acute rejection, viral infection, or pancreatitis. One patient had three days of melena and responded to non-operative therapy. The fourth patient developed ischemic colonic changes 10 weeks after allograft nephrectomy and was receiving no immunosuppression at the time. Broad spectrum antibiotics were used at various times in all patients. Early aggressive evaluation of gastrointestinal complaints--including barium enema, upper gastrointestinal series with small bowel follow-through, proctosigmoidoscopy or colonoscopy, and arteriography--is indicated, in view of the lethality of the complication of colonic ulceration. The clinical pictures presented emphasize the fact that recipients of renal allografts are commonly heir to many complications which may be considered rare in the normal population.

Adult↗
PubMed2004

Determination of polymeric aluminum in soil extracted with a modified anion-exchange resin as a solid-phase adsorbent by ICP-AES.

In the present work, a new method was established by applying solid-phase extraction (SPE) to preconcentrate and separate polymeric aluminum (Al) and using ICP-AES to determine the polymeric Al, the total monomeric Al, and the total Al in soil extracts, respectively. A modified resin was prepared with impregnated 8-hydroxyquinoline-5-sulfoxinate (HQS) on the anion-exchange resin. It has good recognition ability for Al fractions, compared to the commonly used cation ion-exchange resin, which has a better ability to adsorb cations and a weak ability to recognize detailed Al species. The optimum conditions for Al fractionation sorption, elution and separation and the interference of foreign ions were studied with the prepared resin by continuous column and batch procedures. Monomeric Al was bound to Pyrocathecol Violet (PCV) at pH 6.2, whereas the polymeric Al species did not react with PCV for at least 15 min. Because a stable complex of Al-PCV was not absorbed on the HQS modified resin, the polymeric Al could be preconcentrated on-line by the HQS-modified resin. The adsorbed polymeric Al was eluted with 3 mL of 3 mol L(-1) of HCl, and then detected by ICP-AES. The method has been applied to directly determine polymeric Al in soil extracts with high selectivity as well as a high preconcentration factor. It gives a limit of detection of 0.6 ng mL(-1) with a relative standard deviation of less than 5.7% (n = 5, 0.24 microg mL(-1) Al).

Journal Article↗
PubMed2001

Soil N fluxes in three contrasting dry tropical forests.

A comparative study of N fluxes in soil among a dry dipterocarp forest (DDF), a dry evergreen forest (DEF), and a hill evergreen forest (HEF) in Thailand was done. N fluxes in soil were estimated using an ion exchange resin core method and a buried bag method. Soil C and N pools were 38 C Mg/ha/30 cm and 2.5 N Mg/ha/30 cm in DDF, 82 C Mg/ha/30 cm and 6.2 N Mg/ha/30 cm in DEF, and 167 C Mg/ha/30 cm and 9.3 N Mg/ha/30 cm in HEF. Low C concentration in the DDF and DEF sites was compensated by high fine soil content. In the highly weathered tropical soil, fine soil content seemed to be important for C accumulation. Temporal and vertical fluctuations of N fluxes were different among the sites. The highest N flux was exhibited at the onset of the wet season in DDF, whereas inorganic N production and estimated uptake of N were relatively stable during the wet season in DEF and HEF. It is suggested that N cycling in soil becomes stable in dry tropical forests to intermediate in temperate forests. N deposition may result in large changes of N cycling in the DDF and DEF due to low accumulations of C and N.

Carbon↗
PubMed2003

Dynamic behavior of adsorber membranes for protein recovery.

In recent years there has been a considerable interest in developing membrane chromatography systems that function as a short, wide chromatographic column in which the adsorptive packing consists of one or more microporous membranes. This study reports the use of new adsorber membranes prepared by the incorporation of various types of ion exchange resins into an EVAL porous membrane for protein recovery. The obtained heterogeneous matrixes composed of solid particles surrounded by the polymeric film possess a good accessibility for the protein to the adsorptive sites. Furthermore, small particles can be embedded into porous polymeric structures without the disadvantages of classical chromatographic columns (high pressure drop, fouling and plugging sensitivity, low flow rate), but with the advantages of membrane technology (easy scale-up, low-pressure drop, high flow rate). The adsorptive membranes feature high static as well as dynamic protein adsorption capacities for operating flow rates ranging from 200 to 400 L h bar per m(2) and ionic strength of 20-200 mM. In a sequential desorption step by changing the pH and/or the ionic strength of the eluent, up to 90% protein recovery was obtained. Next to the separation, the mixed matrix adsorber membrane functions as a concentration medium since the protein can be concentrated up to 20-fold in the eluent. The adsorber membranes can be reused in multiple adsorption/desorption cycles with good adsorption performances.

Adsorption↗
PubMed2001

Nitrate reduction with Halomonas campisalis. Kinetics of denitrification at pH 9 and 12.5% NaCl.

Regeneration of ion exchange resins with NaCl produces brine containing high concentrations of nitrate that can be difficult to remove using standard biological, physical, or chemical technologies. In this study. Halomonas campisalis (ATCC #700597) (Mormile et al., 1999) was shown to completely reduce nitrate at 125 g/L NaCl and pH 9. This organism was also used in experiments to determine nitrate-reduction rates and biomass yields. Kinetic parameters were measured separately with glycerol, lactate. acetate, ethanol, and methanol. The specific nitrate-reduction rate coefficient was highest in cultures amended with acetate, while lactate and glycerol (a natural osmoticum in hypersaline environments) had lower reduction rates. No evidence of nitrate reduction was observed when ethanol or methanol was provided as an electron donor. Kinetic modeling provided values for nitrate and nitrite-reduction rate coefficients and for biomass yields. Measured rates and yields were similar to reported parameters obtained from non-halophilic nitrate-reducing cultures under low salt concentrations. Therefore, for highly saline solutions, the use of halophiles to selectively remove nitrate from these brines may represent a viable treatment option.

Halomonas↗
PubMed1989

Connective tissue responses to some heavy metals. III. Silver and dietary supplements of ascorbic acid. Histology and ultrastructure.

Silver-loaded ion exchange resin beads implanted into loose connective tissue of the rat pinna produced a local reaction. Initially the lesion comprised local necrosis and tissue disruption with predominantly small round cell infiltration. The subsequent organization was delayed and disordered. Fibroblasts developed grossly dilated cisternae of the rough endoplasmic reticulum. The matrix contained poorly orientated collagen fibrils of varying size and ground substance appeared condensed and granular. Distorted collagen fibrils were identified within membrane-bound vacuoles in the cytoplasm of both fibroblasts and macrophages. Abnormalities of the silver lesion were indicative of disordered collagen biosynthesis. Silver interfered with the biosynthesis and assembly of matrix components of the connective tissue. The reaction to silver beads in rats maintained on a diet heavily supplemented with ascorbic acid approached that of the control (sodium-loaded bead) with respect to the time scale, tissue reaction and tissue organization. The collagen matrix which formed was more organized and of greater density than that in the rat maintained on a normal diet. However, the repair tissue retained some of the morphological features of the legacy of silver toxicity, in particular delayed repair and dense intracellular fibrils within fibroblasts and macrophages. The excess of ascorbic acid partially ameliorated the effect of silver, possibly by compensating catabolysis of ascorbic acid caused by the presence of the released silver.

Animals↗
PubMed1984

Microcontrolled release of biologically active compounds in chick embryos: beads of 200-microns diameter for the local release of retinoids.

A method of controlled release that allows the continuous local application of retinoids (vitamin A derivatives) in living tissues has been developed. Several biocompatible 200-microns-diameter polymeric beads have been tested as possible carriers. Each type of bead was loaded by soaking in an isotopically labeled retinoid solution, washed, and then transferred into tissue culture medium for quantitative release measurements. Positively-charged ion-exchange resins of the Dowex 1 type were found to be the most suitable for the controlled release of retinoic acid, a negatively charged compound. For the controlled release of uncharged retinoids such as retinyl acetate, uncharged acrylic ester polymer beads are preferred; these beads can also be used to release the negatively charged compounds retinoic acid and prostaglandin E1. In all cases, a prolonged release is obtained that persists for more than a day. During this interval, the release is diffusion-controlled, and the total amount of compound released is directly proportional to the amount of the compound that the bead is exposed to during the initial loading step. High-performance liquid chromatography has been used to analyze the nature of the released retinoid. When the positively charged beads are loaded with all-trans-retinoic acid, there is a time-dependent decrease in the proportion of the all-trans isomer released which is due to an increased release of two cis isomers. This isomerization reaction occurs at a considerably slower rate when the uncharged beads are used as carriers. To mimic the conditions under which the local release of retinoic acid causes striking pattern duplications in developing chick wings, beads loaded with isotopically labeled retinoids were manually implanted into a slit cut into wing buds of stage-20 chick embryos. The release rate obtained was comparable to that found in vitro, and a time-dependent accumulation of the released radioactive compound was measured that was confined to the tissue near the site of implantation. All of the beads tested were readily accommodated by the tissue and could be easily removed at any time to terminate the treatment. It is believed that the controlled release of chemicals from such tiny biocompatible implants has a wide potential range of applications in biology.

Adsorption↗