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[Effect of electro-immobilization on Bacillus subtilis].

The culture of Bacillus subtilis 21 was subjected to the action of nonuniform electric field, and the effect of the latter on the bacterial survival and biochemical activity was studied. The action of the field on the cells was shown to depend on the material of a load on which the culture was immobilized. The studied properties of Bac. subtilis 21 did not change when the culture was immobilized on cellulose fiber. About 50--60% of the cells died on silica gel under the action of field; the respiration activity and the rate of hexamethylene diamine destruction did not change. Almost all of the bacterial cells lost their viability upon electroimmobilization on ion-exchange resins. The destructive properties of the culture retained by the field exceed the activity of the control variants.

Bacillus subtilis↗
PubMed1998

[The pathophysiology and treatment of cholestatic pruritus].

Pruritus is a frequent, distressing and sometimes disabling symptom of liver and biliary tract disorders. Results of treatment are sometimes disappointing and the pathophysiology is still largely unknown. It was recently discovered that endogenous opioids contribute to the perception of itching and that opiate receptor antagonists can reduce the overstimulation of these receptors and thereby attenuate the itching. A stepwise treatment strategy focusing successively on ion exchange resins, rifampicin and opiate receptor antagonists leads to effective alleviation of itching in most patients.

Cholestasis↗
PubMed1995

A simple and effective method for the removal of trace metal cations from a mammalian culture medium supplemented with 10% fetal calf serum.

Direct batch addition of sterile Chelex ion-exchange resin to Dubecco's modified Eagle's medium supplemented with 10% fetal calf serum with gentle stirring removed a very wide variety of trace metal ions from the medium to varying extents dependent upon Chelex content (between 0.01 and 4% w/v), exposure time (between 5 min and 10 days) and temperature (4, 25 and 37 degrees C). Prolonged treatment (10 days) with 4% w/v Chelex at 4 degrees C reduced the concentration of zinc, strontium, aluminum, copper, manganese, nickel and chromium from 100 to 2.7, 12.1, 7.7, 22.6, 13.0, 14.7 and 53.3% of their original concentrations, respectively. Re-supplementation of the metal depleted medium with a defined cocktail of metals restored the growth potential of the medium which was then capable of supporting growth over at least three subcultures without a decrease in fibroblast cell yield, demonstrating its suitability in cell culture studies on trace metal ions.

Animals↗
PubMed1998

Adsorptive control of water in esterification with immobilized enzymes: II. fixed-bed reactor behavior.

Experimental and theoretical studies are conducted to understand the dynamic behavior of a continuous-flow fixed-bed reactor in which an esterification is catalyzed by an immobilized enzyme in an organic solvent medium. The experimental system consists of a commercial immobilized lipase preparation known as Lipozyme as the biocatalyst, with propionic acid and isoamyl alcohol (dissolved in hexane) as the reaction substrates. A complex dynamic behavior is observed experimentally as a result of the simultaneous occurrence of reaction and adsorption phenomena. Both propionic acid and water are adsorbed by the biocatalyst resulting in lower reaction rates. In addition, an excessive accumulation of water in the reactor leads to a rapid irreversible inactivation of the enzyme. A model based on previously-obtained adsorption isotherms and kinetic expressions, as well as on adsorption rate measurements obtained in this work, is used to predict the concentration and thermodynamic activity of water along the reactor length. The model successfully predicts the dynamic behavior of the reactor and shows that a maximum thermodynamic activity of water occurs at a point at some distance from the reactor entrance. A cation exchange resin in sodium form, packed in the reactor as a selective water adsorbent together with the catalyst particles, is shown to be an effective means for preventing an excessive accumulation of water formed in the reaction. Its use results in longer cycle times and greater productivity. As predicted by the model, the experimental results show that the water adsorbed on the catalyst and on the ion exchange resin can be removed with isoamyl alcohol with no apparent loss in enzyme activity.

Adsorption↗
PubMed1970

Rat small-intestinal beta-galactosidases. Studies on the fractionation of "acid" beta-galactosidase with isoelectric focusing, gel filtration and ion-exchange chromatography.

1. Different forms of the rat small-intestinal ;acid' beta-galactosidase were separated by using the isoelectric-focusing technique. The isoelectric points of the different forms were at pH4.2, 4.6, 5.4, 6.1 and approx. 8. 2. The two forms of ;acid' beta-galactosidase isoelectric at pH4.2 and 4.6 were completely excluded from the Sephadex G-200 gel, whereas the form isoelectric at pH8 had K(av.) 0.4. The concentration and pH of the elution buffer influenced the distribution of enzyme activity between different forms. Thus, under certain conditions of ionic strength and pH, the enzyme seems to form high-molecular-weight aggregates with low isoelectric points. These may be homopolymeric aggregates or the result of binding of enzyme to, for example, membrane fragments. The forms isoelectric at pH5.4 and 6.1 are probably aggregates of intermediate size. 3. During ion-exchange chromatography at pH6.0 one fraction of ;acid' beta-galactosidase was not retained on the column and was isoelectric at pH8 and another fraction was eluted when the buffer concentration in the eluate had increased to about 50mm. The main part of enzyme eluted in this second fraction was also isoelectric at pH8, indicating that the elution of this fraction is not a simple ion-exchange procedure but probably also involves a splitting of high-molecular-weight aggregates, originally retained because of their low isoelectric points. The enzyme subunits have a higher isoelectric point, and are therefore no longer bound to the ion-exchange resin.

Animals↗
PubMed1970

Spin-echo nuclear magnetic resonance evidence for complexing of sodium ions in muscle, brain, and kidney.

Na(+) in muscle, brain, and kidney is shown by spin-echo nuclear magnetic resonance (NMR) to consist of two fractions with different NMR parameters. The slow fraction of Na(+) in these tissues has NMR relaxation times T(1) and T(2) of 10-15 x 10(-3) sec, which is approximately 4-5 times shorter than for Na(+) in aqueous NaCl solution. The slow fraction may represent Na(+) dissolved in structured tissue water. The fast fraction of tissue Na(+), which is shown to represent approximately 65% of the total tissue Na(+) concentration, has T(2) less than 1 x 10(-3) sec, which resembles the values of T(2) observed for Na(+) complexed by synthetic ion-exchange resins. One is drawn to the conclusion that approximately 65% of total Na(+) in muscle, brain, and kidney is complexed by tissue macromolecules.

Animals↗
PubMed1998

Chemically-tagged Mitsunobu reagents for use in solution-phase chemical library synthesis.

A general method for high-throughput product purification of Mitsunobu reactions is described. Tagged phosphine and azodicarboxylate reagents are used to synthesize individual library members in solution-phase. Workup and purification are easily accomplished by post-reaction sequestration of the tagged reagents and reagent byproducts by a complementary functionalized ion exchange resin. The reagents are utilized in a 3 step library synthesis.

Chemistry, Organic↗
PubMed1972

Cephamycins, a new family of beta-lactam antibiotics. II. Isolation and chemical characterization.

Cephamycins A and B were isolated from the same fermentation broth of various actinomycetes by adsorption and ion-exchange methods. The antibiotics were separated from each other by column chromatography on a dextran-based ion-exchange resin. Cephamycin C was isolated from a different fermentation broth by ion-exchange and gel-filtration methods. The chemical characteristics of these new antibiotics were determined.

Anti-Bacterial Agents↗
PubMed1992

Comparative bioavailability of a sustained-release ion-exchange hydralazine product with a potassium (cation) challenge.

A sustained-release formulation of hydralazine was manufactured by binding hydralazine to an ion-exchange resin and coating the drug-resin complex with a semipermeable membrane. Because the sustained-release characteristics are due in part to displacement of drug from the drug-resin complex by gastrointestinal ions, the stability of the sustained-release formulation could be compromised if challenged by a high concentration of ions. In this study, 12 healthy male volunteers participated in a two-way crossover trial that was designed to test the bioavailability and release of drug from the sustained-release formulation both with and without concomitant ingestion of a solution of KCl. Blood samples were collected over a 14-h period after administration of either treatment. Analysis of whole blood for hydralazine and comparison of the values of the area under the curve of the concentration of hydralazine versus time, the maximum concentration of hydralazine, and the time to reach the maximum concentration between the two experimental groups showed that KCl had no influence on the bioavailability or release characteristics of hydralazine from the sustained-release formulation.

Adult↗
PubMed1965

Microbiological assay of vitamin B12 in the presence of tetracycline.

Treatment of a pharmaceutical preparation of vitamin B(12) and tetracycline with an ion-exchange resin by the batch method differentially adsorbed tetracycline, making possible a statistically reproducible microbiological assay of vitamin B(12) by the standard Escherichia coli plate method.

Biological Assay↗
PubMed1972

Contact-mediated reversible suppression of myogenesis. II. Reversal of suppression by bromodeoxyuridine.

Chondrocytes from the vertebral columns of 11-day chick embryos were cultured in the continuous presence of 5-bromodeoxyuridine (BUdR) Under these conditions the cells form multilayers but synthesize little extracellular matrix as determined by toluidine blue metachromasia or sulfate-(35)S incorporation into polysaccharide. Myogenic cells from the breast muscles of 11-day chick embryos formed myotubes when plated into BUdR-treated chondrocyte cultures. When plated on untreated chondrocyte multilayers or on multilayers which had been permitted to recover from BUdR treatment for 3 days, myogenic cells failed to form myotubes Since extracellular matrix is present in untreated chondrocyte cultures and reappears in multilayers recovering from BUdR treatment, it is suggested that extracellular matrix is the active agent in the suppression of myogenesis An attempt was made to duplicate the suppressing activity of multilayer cultures by using ion exchange resins as substrates for myogenic cells Myotubes formed on acidic and basic resin particles If extracellular matrix is the active suppressing agent, it may have to fulfill certain spatial distributional requirements before its activity is expressed

Animals↗
PubMed1977

Influence of histone H1 on chromatin structure.

Removal of histone H1 produces a transition in the structure of chromatin fibers as observed by electron microscopy. Chromatin containing all histone proteins appears as fibers with a diameter of about 250 A. The nucleosomes within these fibers are closely packed. If histone H1 is selectively removed with 50-100 mM NaCl in 50 mM sodium phosphate buffer (pH 7.0) in the presence of the ion-exchange resin AG 50 W - X2, chromatin appears as "beads-on-a-string" with the nucleosomes separated from each other by distances of about 150-200 A. If chromatin is treated in the presence of the resin with NaCl at concentrations of 650 mM or more, the structural organization of the chromatin is decreased, yielding fibers of irregular appearance.

Animals↗
PubMed1976

[The influence of neuroleptic drugs on urinary excretion of non-protein nitrogen (author's transl)].

During treatment with thioxanthenes or phenothiazines of schizophrenic patients non-protein nitrogen in urine was measured. The values were calculated in relation to the excretion of creatinine. a) Flupentixol or fluphenazine applied in optimal dosage, increased the excretion of urea and the amino acids asp, glu + gln, and gly. b) Moreover, if the drug induced a parkinsonoid (thioridazine) the excretion of ser and thr was increased, too. The usual desalting procedure by ion-exchanging resins before chromatography increases the contents of several amino acids, e.g. asp, asn, ala, gly, cys, ser, thr, indicating a breakdown of some instable products.

Amino Acids↗
PubMed1983

[A system for decontamination of liquid radioactive waste produced in in vitro tests in nuclear medicine].

It is well known that very large storage tanks for radioactive liquids are necessary for the disposal of liquid radioactive waste. In vitro tests in radioimmunoassay in nuclear medicine are rapidly increasing for clinical examination causing marked increase in the volume of liquid radioactive waste. Thus we have developed a system for decontaminating radioactivity from liquid waste. In the first step, the liquid waste is boiled by a sterilizer and, in the second step, this sterilised liquid is filtered by a cylindrical filter (Toyo filter No. 84). After filtration, the liquid waste is passed into a beaded charcoal column and an ion exchange resin (Amberlite IRA 402) column. After these treatments, the radioactivity level of liquid waste is lowered to less than 1% of the original radioactivity. We are now in the planning stages of building an apparatus for practical use.

Filtration↗
PubMed1977

Rubidium-82 generators for imaging studies.

Strontium-82, produced by spallation reaction with medium-energy proton beams, was used to evaluate Bio-Rex 70 and Chelex-100 ion-exchange resins for use in a compact Rb-82 generator. Adsorption of Sr-82 to the resin column, Rb-82 elution yields, Sr breakthrough, and 82Rb-Sr separation factors were determined for newly prepared columns and for longterm elution conditions. Separation factors of 10(7) to 10(8) were obtained with 2% NaCl elutions from Bio-Rex 70 resin columns while the separation factors was about 5 X 10(4) with the Chelex-100 resin column.

Evaluation Studies as Topic↗