PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “COUNTERCURRENT DISTRIBUTION”

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 19 recordsLinked to original sources
PubMed1987

Elution countercurrent distribution.

The single withdrawal technique, here called elution countercurrent distribution, was applied for the first time on aqueous two-phase systems. The modifications necessary for elution countercurrent distribution of a thin-layer countercurrent distribution apparatus are described. The results from a test run with sulfuric acid showed good agreement between the experimental and the theoretical curves for elution countercurrent distribution. Thylakoid membrane vesicles from spinach chloroplasts were subjected to the elution countercurrent distribution. A gradient of NaCl in the eluting upper phase was used to elute the different fractions in order of their affinity for the moving upper phase. Inside-out thylakoid vesicles were resolved into two major and several minor fractions having different chlorophyll a/b ratios. Sonicated inside-out thylacoid vesicles were resolved into at least five different fractions with different chlorophyll a/b ratios. An increased resolution is obtained with elution countercurrent distribution compared to the fundamental process.

Chlorophyll↗
PubMed1994

Acquisition of viable-like surface properties of sperm cells by adsorption of seminal plasma proteins revealed by centrifugal countercurrent distribution.

By using centrifugal countercurrent distribution in dextran/polyethylene glycol two-phase system, we show that the acquisition of adsorbed seminal plasma proteins by the sperm cell surface modifies the partition behaviour of bull spermatozoa reproducing that of alive cells. Thus, addition of increasing concentrations of proteins from the seminal plasma promoted a saturable enhanced affinity of the cells to the polyethylene glycol-rich phase in which alive cells preferentially partition. On the contrary, treatment with Tween provoked the opposite effect.

Adsorption↗
PubMed1993

Quantification of countercurrent distribution: from molecular partition to animal behavior.

Countercurrent distribution is a very effective method for separating a variety of substances including molecules, cells, and animals on the basis of partition between two solvent or behavioral phases. Distribution of a substance in this multi-cycle procedure can be described in terms of its partition coefficient (K) or the fraction of the substance that moves to the mobile phase in each cycle (p). It is currently difficult to calculate the value of p or K directly from an experimental distribution. Such direct calculation will simplify comparison of various experimental populations for the properties which determine their distribution, such as the surface properties of cells or behavioral preferences of animals. This report describes, and provides a theoretical basis for, an extremely simple method to calculate p or K directly from an experimental countercurrent distribution.

Animals↗
PubMed1975

Fractionation of mucopolysaccharides by countercurrent distribution in aqueous polymer two-phase systems.

A new procedure for the fractionation of mucopolysaccharides based upon differences in their partition behavior in aqueous polymer two-phase systems has been devised. Systems containing dextran, poly(ethylene glycol), trimethylamino-poly(ethylene glycol), potassium bromide and sodium phosphate buffer were employed. Countercurrent distributions were performed with a miniature countercurrent distribution device designed especially for use with aqueous polymer two-phase systems. An advantage over the widely used procedures involving precipitation of mucopolysaccharides as their quaternary ammonium detergent complexes is that the countercurrent distribution pattern of a particular mucopolysaccharide is not affected by the simultaneous presence of other mucopolysaccharides. Preliminary distributions of labelled mucopolysaccharides isolated from the cells and culture medium of monolayer cultures of rat tumor cells demonstrate that the procedure is particularly well suited for the fractionation of very minute quantities of mucopolysaccharides.

Cell Line↗
PubMed1967

Countercurrent-distribution studies on histones.

1. The possibilities of fractionating histones and histone fractions by means of countercurrent distribution between two phases formed by water and butan-2-ol, in the presence of various concentrations of trichloroacetic acid, have been examined. 2. Although the principal histone fractions differ considerably in their partition ratios, a satisfactory resolution of the principal histone fractions from the whole histone has not been achieved. 3. The histone fractions obtained by other methods can be resolved with suitable concentrations of trichloroacetic acid. Besides the main peak several subsidiary peaks are obtained in most cases, the composition of which corresponds with others of the main fractions. 4. The method is therefore capable of removing from the principal fractions as previously prepared contamination by other fractions. 5. Except in one case, no fraction with composition unlike other fractions has been obtained. In several cases the material isolated from the principal peak behaves as a single component on running again. In two cases fractions with similar compositions were distinguished by countercurrent distribution.

Acids↗
PubMed1984

Separation and subfractionation of small numbers of cells (approximately 10(6)) by countercurrent distribution in dextran-poly(ethylene glycol) aqueous-phase systems.

Separation and subfractionation of cells on the basis of subtle differences in surface properties by partitioning in dextran-poly(ethylene glycol) aqueous phase systems is an established method. We report here that the incorporation of fetal bovine serum into such systems permits countercurrent distribution of small quantities of cells (approximately 10(6]. In the absence of serum such small quantities of cells are lost (probably by adherence) and cannot be recovered after countercurrent distribution.

Animals↗
PubMed1989

Studies of protein-protein interaction using countercurrent distribution in aqueous two-phase systems. Partition behaviour of six Calvin-cycle enzymes from a crude spinach (Spinacia oleracea) chloroplast extract.

The partition behaviour of six enzymes of the Calvin cycle in extracts of chloroplasts from spinach (Spinacia oleracea) between two aqueous phases has been studied by countercurrent distribution. The enzymes showed distribution patterns which indicate heterogeneity and the presence of two or three fractions of most of the enzymes. When two of the enzymes, phosphoglycerate kinase and fructose-bisphosphate aldolase, were partitioned in both purified and partially purified form, they behaved like homogeneous substances. These results indicate that countercurrent distribution of crude extracts in aqueous two-phase systems is a useful method to study protein-protein interaction.

Brassica↗
PubMedDate not supplied

Separation of ram spermatozoa bearing X and Y chromosome by centrifugal countercurrent distribution in an aqueous two-phase system.

The availability of reliable quantification techniques of X and Y chromosome-bearing spermatozoa in a given insemination dose would allow further approaches to their separation, which is a topic of unquestionable interest in animal production. The aim of the current work was the development of a combined approach of polymerase chain reaction and countercurrent distribution to address both objectives. First, using Sac/polymorphisms for ZFX/ZFYloci in sheep deoxyribonucleic acid, a linear correlation has been established between the densitometric quantification of the restricted fragment length polymorphisms corresponding to the amplified loci ZFX/ZFY by polymerase chain reaction and the theoretical proportions of X and Y chromosomes in standard solutions. The method, subsequently applied to semen samples, estimated an equal proportion of spermatozoa bearing each chromosome. Second, by using centrifugal countercurrent distribution in a sensitive-charge aqueous two-phase system, we achieved the separation of a sperm population enriched in Y chromosome-bearing ram spermatozoa (75%) with a high viability rate (57%).

Animals↗
PubMed1967

Countercurrent distribution studies on hamycin.

Hamycin, a polyene antifungal antibiotic, was isolated by use of countercurrent distribution. A pattern was obtained by plotting the absorption at 383 mmu of the contents of the various tubes against the tube numbers. The results indicated that the antibiotic contained three fractions, a major fraction (peak 2) comprising 48% of the total activity and two minor fractions (peak 1 and peak 3) comprising 3.62 and 11.32%, respectively, of the total activity. The solid material was isolated by pooling the contents of the tubes containing the major fraction, concentrating this in vacuo, and cooling. The antibiotic activities of the three peaks were evaluated by use of a cup-plate assay method with Paecilomyces varioti as test organism. All three components showed antibiotic activity; however, the preparation obtained from the major fraction showed approximately a 7-fold increase in antibiotic activity, a doubling of the E(1cm) (1%) value at 383 mmu, and approximately a 2.5-fold decrease in the amino acid content in comparison with the starting material. There was an apparent correlation obtained by plotting the curves of the absorption at 383 mmu of the different tubes comprising the major fraction and their biological activities.

Antifungal Agents↗
PubMed1992

Fractionation of human neutrophils into subpopulations by countercurrent distribution: surface charge and functional heterogeneity.

Isolated blood neutrophils from normal healthy subjects were separated into fractions by sequential countercurrent distribution (CCD) in a charge-sensitive dextran/polyethylene glycol aqueous phase system. The neutrophils separated as a broad profile, and in a charged phase procedure the separation was based upon differences in cell surface electrokinetic properties, as confirmed by electrophoretic mobility measurements of fractions across the profile using analytical cytopherometry. The CCD cell fractions were generally pooled as three or four major subfractions for analysis of functional and metabolic differences. These included measurements of chemotaxis, phagocytosis, and respiratory burst. An inverse relationship was found between the electrophoretic mobility (EPM) of the subfraction pools and their functional competence, with the less electronegative cell fraction pools often as much as 2 to 3-fold more active than the more electronegative pools. This demonstration of electrokinetic and functional heterogeneity in 'resting' neutrophil subpopulations separated by CCD may reflect changes during their sojourn in the circulation that determine selective margination and recruitment of cells to inflammatory foci and sites of infection.

Cell Separation↗
PubMed1984

Separation of rat testis cells by a manually operated countercurrent distribution apparatus. I. Partition behaviour of cells in aqueous two-phase system.

The partition behaviour of rat testis cells in an aqueous two-phase polymer system has been studied using a simplified version of the countercurrent distribution apparatus. The influence of the phase system on testis cells has been presented. The manually operated apparatus designed has shown a fair enrichment of cell types, depending on their surface properties. In respect to their developmental stages, different cell types have shown their specific rate of migration through the CCD tubes. Non-germinal cells, mainly the Sertoli cells, have been seen to have a higher migration rate than the spermatids and spermatocytes. The pachytene spermatocytes have the lowest migration rate.

Animals↗
PubMed1990

Studies of protein-protein interaction using countercurrent distribution in aqueous two-phase systems: partition behavior of five glycolytic enzymes from crude baker's yeast extract.

The partition behavior of five glycolytic enzymes, in extracts from baker's yeast (Saccharomyces cerevisiae), between two aqueous phases has been studied by countercurrent distribution. All enzymes showed distribution patterns which indicated homogeneity and a similar partition behavior. In purified form, three of the enzymes (glyceraldehyde-phosphate dehydrogenase, 3-phosphoglycerate kinase, and enolase) showed the same partition behavior as in the extracts. Pure 6-phosphofructokinase, on the other hand, changed its partition distinctively relative to what was found in the extracts. These results indicate interactions between this enzyme and macromolecular compounds in the extracts and support a model suggested by Kurganov et al. (1985, J. Theor. Biol. 116, 509-526) describing a "glycolytic particle."

Countercurrent Distribution↗
PubMed1969

Countercurrent distribution of inosol lipids of plant seeds.

The inositol lipids of plant seeds consist of phosphatidyl inositol, the phytoglycolipids, and a previously uncharacterized ceramide-phosphate-polysaccharide. These three species have been separated from each other and from the common glycerophosphatides by a series of simple countercurrent distributions, first as the naturally occurring Ca-Mg salts and subsequently in the Na salt form. The new ceramide-phosphate-polysaccharide is present in each of the four plant phosphatides examined (corn, soybean, flax, safflower). It is devoid of glucosamine but contains the other carbohydrate components commonly found in the phytoglycolipids. The basic structural unit of the new glycolipid consists of a ceramide-phosphate-inositol-hexuronic acid moiety to which the other sugars (galactose, mannose, arabinose) are attached. Flax ceramide-phosphate-polysaccharide has fucose in addition to the other sugars.

Amino Alcohols↗
PubMed1984

Cell separations and subfractionations by countercurrent distribution in two-polymer aqueous phase systems depend on non-equilibrium conditions.

Certain kinetic aspects of the partitioning behavior of erythrocytes in dextran-poly(ethylene glycol) aqueous phase systems have been examined, and their implications for cell partitioning have been considered. It is concluded that the diverse and sometimes unique fractionations attained by use of multiple extractions (e.g., countercurrent distribution) of cells in two-polymer aqueous-phase systems depend on non-equilibrium conditions.

Animals↗
PubMed1975

[Countercurrent distribution of polysulfonated proteins (author's transl)].

The reaction of bovine beta-lactoglobulin AB with reagents 4-(isothiocyanato) benzene sulfonic acid, 5-(isothiocyanato) benzol-1,3-bis(sulfonic acid) and 7-(isothiocyanato) naphthalene-1,3,5-tris(sulfonic acid) is described. The blocking of the epsilon-amino groups of lysine is quantitative. The thus modified protein can be analysed in the countercurrent distribution apparatus and can be split very rapidly at the arginine residues with trypsin.

Animals↗