SEARCH · PubMed Health
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.
The histologic appearance of Kayexalate, an ion-exchange resin, in bronchioles and alveolar spaces is described. Aspiration of this material occurred as a terminal event in an infant who suffered neonatal asphyxia and meconium aspiration. A solution of Kayexalate prepared for comparison appears to be identical to that found in the lung sections.
Osteoblasts, from the endocranial surface of neonate rat parietal bones, migrated over ion-exchange resin beads and phase-separation beads in vitro. The morphology of migrated osteoblasts was examined using a scanning electron microscope. The ion-exchange resin beads were either positively or negatively surface charged. The phase-separation model system described, using poly(methyl methacrylate) (PMMA) and lead poly-acrylate (LPA), presented morphologically discrete regions of positive and negative surface charge to single migrating osteoblasts. Osteoblasts migrated over both positively and negatively charged substrata. Close approximation of cells was noted on positively charged surfaces while a 'stand-off' morphology was characteristic of cells on negatively charged substrata. Dorsal cell-surface membrane activity was influenced by the surface charge of the colonized substratum.
The synthesis of dodecyl pyroglutamate (or pyroglutamate lauroyl ester) was achieved in a two-step process involving a pyroglutamic acid alkyl ester intermediate. The reaction was carried out either by lipase or by chemical catalysis using ion exchange resin. Among the various tested lipases, the one from Candida antarctica B gave the best results allowing 73% formation of the desired ester after 6 h. Comparing the efficiency of this latter lipase with the one of Amberlyst IR120H resin in catalyzing this reaction, the biocatalyst gave a molar yield of pyroglutamate lauroyl ester of 79% compared to 69% when using the ion exchange resin starting with 1.04 mmol substrate in each case.
It has been demonstrated experimentally that small numbers of a variety of different bacteria fail to survive or multiply in normal cow or human blood or in a mixture of blood and a suitable culture medium, owing to the binding of the magnesium ion and a protein component of the antimicrobial system. However, a satisfactory and simple method has now been evolved for the rapid multiplication of Gram-negative and Gram-positive bacteria in blood without the addition of a liquid culture medium. This method involves the addition to blood of optimum amounts of hydrogen and magnesium ion exchange resins and sodium citrate.
The influence of temperature (293 308 K 1:1 IDA:Ni2+ complex is dominating. The Cu2+-Ni2+ exchange equilibrium from sulfate medium is characterized by the formation of nickel complexes of both stoichiometries within the whole temperature range studied. The dependence of alpha on T in Zn2+-Co2+ exchange system has been shown to be weaker than that in the Cu2+-Ni2+ system. This result is in a good agreement with the predictions made in the first communication of this series. The results of thermostripping experiments carried out for Cu2+-Co2+ exchange have shown that the efficiency of the thermostripping process depends on both the interval of working temperatures (deltaT) and its position on the temperature scale. The efficiency of thermostripping rises with an absolute deltaT value and also increases following the shift of temperature interval to the lower temperature range.
Protein dynamic binding capacities on ion exchange resins are typically expected to decrease with increasing conductivity and decreasing protein charge. There are, however, conditions where capacity increases with increasing conductivity and decreasing protein charge. Capacity measurements on two different commercial ion exchange resins with three different monoclonal antibodies at various pH and conductivities exhibited two domains. In the first domain, the capacity unexpectedly increased with increasing conductivity and decreasing protein charge. The second domain exhibited traditional behavior. A mechanism to explain the first domain is postulated; proteins initially bind to the outer pore regions and electrostatically hinder subsequent protein transport. Such a mechanism is supported by protein capacity and confocal microscopy studies whose results suggest how knowledge of the two types of IEX behavior can be leveraged in optimizing resins and processes.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Based on a flow-injection spectrophotometry, an automatic analytical method for determination of ppb-level chloride-ion has been established. By use of this method, a novel FIA method for the determination of SBAER performance has also been developed. In this paper, the effects of concentration, dosage, and flow rate of the regenerant on BEC of SBAER were first investigated dynamically by the FIA method. In addition, the flow rate of the sample water and the temperature of the ion exchange resin were also examined. The optimum conditions were obtained: the volume of the regenerant (sodium hydroxide) was 50 mL (0.15 g resin), and its concentration was 3% (w/v); the volumetric flow rates of the regenerant and the sample water were 0.5 ml/min (4.3 m/h) and 1.5 ml/min (13 m/h), respectively. The exchanging temperature was 25 +/- 5 degrees C. The method is characterized by the use of a micro resin-column, shorter testing cycle, easy operation, and high reproducibility. The proposed method is approximately 30 times more efficient than the manual method, and it can be used for the exchange performance comparison of various SBAER.
A procedure in which anionic analytes, trapped on ion exchange resin, are simultaneously methylated and released using methyl iodide in either supercritical carbon dioxide or acetonitrile has been extended to polyfunctional organic acids. The combined SFE methylation of fruit juice acids trapped onto ion exchange resin proceeds in good yield producing the methyl esters of fumaric, succinic, malic, tartaric, isocitric and citric acids which are readily separated by GC. Using this procedure low concentrations of one acid can be detected and quantitated in the presence of very high concentrations of another. This new method detects tartaric acid at levels of 10 ppm in juices containing 10,000 ppm citric acid. Quantitation was performed either by using GC-FID with triethyl citrate or diethyl tartrate as internal standards or with the element specific calibration capability of the GC-AED. A simple new technique for the determination of citric/isocitric acid ratio is now available. Also, in contrast to HPLC methods, the identity of an analyte is readily confirmed by GC-MS.
Experiments were carried out in pigs to ascertain to what extent the cation exchangers Ujolyt and Campanyl used in the prevention of urinary stones undergo persorption and appear in the urine. We used two preparations of different grain size and detected them by labelling with 35S. A maximum of 0.5% or 5 X 10(-3) of the dose was found as persorbed particles at 51 h, chiefly in the muscles. The number of persorbed particles from the fine-grained preparation was considerably greater than that from the coarse-grained product. The urine contained the smallest proportion of particles, less than 2 X 10(-5) of the dose. In view of these results there is no reason to believe that solid particles persorbed during treatment with ion exchange resins can act as crystallization centres for stone formation, and it is equally unlikely that ion exchangers have to reach the urine before they can exert their effect.
Data on the study of antibiotic production by the representatives of Micromonospora and the use of ion exchange resins for intensification of screening antibiotic-producing organisms among Micromonospora are presented. It was found that out of 172 strains of Micromonospora tested 92 (53.5 per cent) cultures produced antibiotics, 18 of which were active against gramnegative bacteria. The use of carboxylic ion exchange resins at early microbiological stages of the screening provided an increase in the frequency of finding broad spectrum antibiotics from 10.4 to 19.7 per cent.
Laboratory studies have been made to evaluate two methods for removing ammonia from blood:-1 The twin-coil artificial kidney was found to produce significant reductions in the ammonia content of outdated human banked blood. After one passage through the coil, levels of up to 9 mug. of ammonia nitrogen per millilitre were reduced to normal, and this effect was maintained when up to 5 litres were passed.2 Ion-exchange resins, in particular a British resin ZK.225 having a 20% divinyl-benzene linkage, were also found to be effective. When passed from an artery directly through an autoclaved resin column to a vein, significant amounts of ammonia were removed from the blood of a dog with pronounced hyperammonaemia. No serious systemic, biochemical, or haematological effects were observed when the blood of three normal dogs was passed through resin columns. All survived, and to date no reason has been found why such a technique could not be used in clinical practice.
Microorganisms destructors of organic compounds contained in the Kremenchug reservoir and water treatment system of heat power station have been distinguished and identified. This system does not completely remove microflora at all stages of technological process that results in infestation of ion-exchange resins of the 1st stage filters for water desalting with microorganisms. The reasons have been established of the 1st stage desalting filters infestation by the reservoir water microflora. It is necessary to form a complex approach to solution of the problem of preventing the accident situations: microbe infestation of ion-exchange resins of water-desalting filters in the system of chemical water treatment of heat power stations.
Endocrine disrupting chemicals (EDCs) are the focus of current environment concern, as they can cause adverse health effects in an intact organism, or its progeny, subsequent to endocrine function. The paper reports on the removal of estrone (E1) and 17beta-estradiol (E2) from water through the use of various adsorbents including granular activated carbon (GAC), chitin, chitosan, ion exchange resin and a carbonaceous adsorbent prepared from industrial waste. The results show that the kinetics of adsorption were adsorbent and compound-dependent, with equilibration being reached within 2 h for a waste-derived carbonaceous adsorbent to 71 h for an ion-exchange resin for E1, and within 7 h for the waste-derived carbonaceous adsorbent to 125 h for GAC for E2. Of all the adsorbents tested, the carbonaceous adsorbent showed the highest adsorption capacity, with a maximum adsorption constant of 87500 ml/g for E1 and 116000 ml/g for E2. The GAC also had a very high adsorption capacity for the two compounds, with a maximum adsorption constant of 9290 ml/g for E1 and 12200 ml/g for E2. The effects of some fundamental environmental parameters including adsorbent concentration, pH, salinity and the presence of humic acid and surfactant on adsorption were studied. The results show that adsorption capacity of activated carbon was decreased with an increase in adsorbent concentration and by the presence of surfactant and humic acid. The results have demonstrated excellent performance of a waste derived adsorbent in removing E1 and E2 from water, and indicated the potential of converting certain solid waste into useful adsorbents for pollution-control purposes.
After enzymatic digestion of chicken myoglobin by trypsin, chymotrypsin or thermolysin, the separation of peptides was performed by column chromatography on various ion exchange resins. Each peptide was purified by high-voltage paper electrophoresis or by chromatography either on paper or on ion-exchange resin, and its complete amino acid sequence was then determined by the combined dansyl-Edman procedure and by endopeptidase digestions. The whole globin was submitted to automatic Edman degradation using the Beckman sequencer. Residues have been positioned from overlaps of sequence data between tryptic (T), chymotryptic (C) and thermolysin (Th) peptides. The stepwise degradation of the whole globin confirmed the alignment of the N-terminal third of the molecule. The combination of these different approaches has led to the complete determination of the 153 residues sequence forming the polypeptide chain of chicken myoglobin. Comparison of the established chicken myoglobin structure with those from other species shows a conservation of structure, although the avian protein exhibits more variations in its amino acid sequence than has been found between other known myoglobins which all belong to mammalian species.
Continuous matrix assisted refolding (MAR) can be achieved on a solid support by using a continuous chromatographic system. Recycling the aggregate fraction, simultaneously formed during a refolding reaction, can further increase the refolding yield. Due to the nature of this reaction, aggregates are the main reason for a refolding yield below stoichiometric conversion. A preparative continuous annular chromatographic system (P-CAC) equipped with an ion exchange resin was used to continuously refold the model protein alpha-lactalbumin. For this purpose, this protein was denatured, reduced and adsorbed on the ion exchange resin. Elution was performed with or without redox reagents in the buffer system permitting fast formation of the native disulfide bonds. In the case redox reagents were present, the protein refolds then during its residence time on the matrix. However, aggregate formation is also increased and refolding yields are lower. Tightly bound aggregates were removed from the column by 2M guanidinium hydrochloride. In order to increase the system yield, this aggregate fraction was recycled after lowering the conductivity by ultradiafiltration and adjustment of the protein concentration by dilution. For on-column refolding, recycling of aggregates at a recycling rate of 0.17 increased the system yield from 25% to 30%. An algorithm was developed to show interdependencies of the single influencing parameters. The operability of the system was demonstrated but limitations due to instability of the P-CAC, especially inhomogeneous flow and peak wobbling, have to be considered.
We have used an atomic force microscope to study the mechanical properties of the matrix found in the lumen of secretory granules isolated from mast cells. The matrices were insoluble and had an average height of 474 +/- 197 nm. The volume of these matrices increased reversibly about tenfold by decreasing the valency of the bathing external cation (La3+ < Ca2+ < Na+). The elastic (Young's) modulus was found to decrease by about 100-fold (4.3 MPa in La3+ to 37 kPa in Na+) upon a tenfold increase in the matrix volume. A swollen granule matrix had an elastic modulus similar to that of gelatin in water. The elastic modulus was inversely related to the change in the volume of the matrix, following a relationship similar to that predicted for the elasticity of weakly cross-linked polymers. Our results show that the matrix of these secretory granules have the mechanical properties of weak ion exchange resins, lending strong support to an ion exchange mechanism for the storage and release of cationic secretory products.