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At least 775 records · Page 43Linked to original sources
PubMed1990

[Comparison of 3 types of cell separators].

The aim of the present investigation was to compare the efficiency of three commercially available cell separators with respect to thrombocyte yields. In addition, advantages and disadvantages of the different cell separator types were studied. There was no difference in the total number of platelets harvested by the different cell separators. In contrast the thrombocyte count of packages from the V 50 device was significantly lower as compared with the others (p = 0.05). We conclude that the cell separators tested are comparable with respect to the efficiency of processing platelet concentrates. However, the larger amount of plasma of the V 50 might be a disadvantage in some circumstances. The AS 104 has advantages in the handling and the duration of cell separation. In addition it offers technical improvements such as control of the ACD flow by a separate adjustable pump and a hemolysis detector.

Blood Transfusion↗
PubMed1986

[The effect of the cell separation procedure on neutrophilic granulocyte function. I. Research on the morphology and phagocytosis behavior of isolated granulocytes].

The investigations were aimed at detecting the impact of various cell separating techniques on the morphology and function of neutrophilic granulocytes. Methodically simple cell separating techniques were used, such as spontaneous sedimentation of ACD-AG blood and mechanically defibrinated blood and a flotation technique which makes use of cell isolation by means of a separating solution and centrifugation. Granulocytes which were isolated by the cell separator Haemonetics M 30 for therapeutic purposes and which, according to data in literature, are not damaged by cell separating techniques were used as reference cells. The electronic-optical evaluation of granulocyte morphology and the in vitro investigation of the phagocytic capacity for rice starch (ingestion rate) of differently isolated granulocytes were made after cell separation.

Cell Separation↗
PubMed1989

Separation of bovine lymphocytes and granulocytes from blood by use of elutriation.

Bovine blood mononuclear cells were separated into 2 fractions by use of centrifugal elutriation. Total recovery, as well as recovery of each fraction, was greater than that obtained by use of Ficoll-sodium diatrizoate separation. The lymphocyte fraction contained less than 1% granulocytes, and the granulocyte fraction contained only 7% lymphocyte contamination. The technique was reproducible and results proved to be comparable with those of Ficoll-sodium diatrizoate density-gradient centrifugation; furthermore, the method is considerably cheaper and less time-consuming for processing large volumes of blood. Viability of cells separated by elutriation always was greater than 98%, whereas viability of cells separated by Ficoll-sodium diatrizaote was greater than 95%. Also, mitogen activation of lymphocytes separated by elutriation was superior to that of lymphocytes separated by Ficoll-sodium diatrizoate centrifugation.

Animals↗
PubMed1987

Polyclonal B-cell activation by a B-cell differentiation factor B151-TRF2. IV. B151-TRF2-responsive F1 B cells consist of two separate populations capable of recognizing only one of the parental I-A products expressed on B cells.

Polyclonal IgM PFC responses of unstimulated B cells induced by a B cell differentiation factor, B151-TRF2, have been shown to involve an Ia-dependent process which is inhibitable by anti-Ia monoclonal antibody (mAb). Moreover, we have demonstrated that when T cell-depleted (B10 x B10.BR)F1 (H-2b/k) spleen cells are fractionated based on their ability to bind to a B10 (H-2b) monolayer, the B151-TRF2 responses of the adherent and nonadherent cell fractions are markedly inhibited by anti-I-Ab and anti-I-Ak mAbs, respectively. From these results, we hypothesized that B cell-recognition of self-I-A products expressed on B cells is involved in the B151-TRF2-induced polyclonal B cell activation. The present study examined the genetic and cellular requirements for the successful separation of F1 B cells with parental monolayers in order to prove recognition by B cells of self-I-A products expressed on B cells. The experiments utilizing monolayers from H-2 congenic strains revealed that identity at the I-A subregion of the H-2 complex between responding F1 B cells and monolayer cells was necessary and sufficient for the successful separation of F1 B cells. In support of this conclusion, purified B cells and B cell lines expressing only parental I-A products on the surface could function effectively as monolayers. Masking of I-A determinants expressed on the monolayer with anti-I-A mAb almost completely abolished the successful separation of F1 B cells, whereas pretreatment of Ia antigens on responding F1 B cells with anti-Ia mAbs did not affect the subsequent separation, indicating involvement of receptor-I-A product interaction rather than like-like interaction in the separation of F1 B cells by the monolayer. The B151-TRF2 responses of purified B cells obtained from athymic nude mice were specifically inhibited by the relevant anti-I-A mAb but not by anti-L3T4 and anti-LFA-1 mAbs, both of which were inhibitory to the Ia-restricted T cell responses. In addition, anti-Thy1.2 mAb plus complement-treated spleen cells from athymic F1 nude mice were successfully fractionated with parental monolayer into two separate populations with restriction specificity for only one of parental I-A products. These results negate the involvement of Ia-restricted T cells in the Ia-dependent process of the B cell activation. Finally, it was demonstrated that there was no apparent difference in the expression of respective parental I-A products between F1 B cell subpopulations adherent and nonadherent to parental monolayers.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1984

Influence of social variables on the biobehavioral response to separation in rhesus monkey infants.

Effects of social stimuli on behavioral and physiological responses to separation were examined in 4-month-old rhesus monkeys. Infants were removed from their social group under 3 counterbalanced conditions: (1) infant totally isolated from its familiar physical and social environment and placed alone in a cage for 4 days; (2) "mother in"--housing the infant in a single cage in front of its social group with mother remaining in the group; (3) "mother out"--similar situation, except that mother was removed from the group during separation. Infant behavior was recorded, and, at selected times during separation, a blood sample was obtained for analysis of plasma cortisol. Infants rarely vocalized when totally isolated, but showed high vocalization and movement in the presence of their social groups. Vocalization was transiently higher in mother-out condition than in mother-in condition. Infants never showed signs of depression. Plasma cortisol response did not differentiate between groups. Animals showed significantly high levels of plasma cortisol 3 hours following separation. These data indicate that the responses of the infant following separation are attempts to produce effective coping responses. The concepts of "protest" and "despair" are discussed as they relate to behavioral differences observed following different separation paradigms.

Animals↗
PubMed1983

The separation of harvested cells from microcarriers: a comparison of methods.

Two techniques are described which have been designed to separate harvested cells from microcarriers. The requirements of efficient recovery and high viability of the cells are met by both procedures. Differences both in size and density between cells and microcarriers allow separations which are based on differential centrifugation or filtration. After trypsinizing the cells from the microcarriers, separation was performed by either ; a) low-speed centrifugation on Ficoll-Paque or, b) filtration through nylon meshes. The methodologies for both techniques are presented. Up to 78% of the total cells were recovered by discontinuous gradient centrifugation using Ficoll-Paque. similar results were obtained when separating Vero, BS-C-1 and MRC-5 cells from Cytodex 1, Cytodex 2 and Cytodex 3 microcarriers. Equally high recoveries were obtained by filtration through an 88 micron pore size nylon mesh. Data are presented for the separation of both Vero and HeLa cells from all 3 types of microcarriers after filtration through 53 and/or 88 micron meshes. Greater than 92% viability of the recovered cells was consistently obtained and their growth properties upon subsequent reculturing were unaffected by either separation procedure. Differential sedimentation by unit gravity provides adequate cell recovery for many applications, but yields are significantly increased by using one or other of the methods described here. Both techniques are rapid and efficient. In addition, differential centrifugation provides a concentrated suspension of the recovered cells, while the nylon meshes for filtration are reusable and can be autoclaved at least 5 times.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1978

[Indications and use of therapeutic component separation].

Therapeutic component separation: Clinical indications and applications. This original communication describes clinical indications, applications and results of the component separation. We have used the Hemonetics cell-separator designed for a discontinuous separation procedure. By this means component separation was rapid and plasma-exchange efficient, which offers a promising way for symptomatic treatment when a qualitative or quantitative modification of the composition of the blood is wanted (e.g. diminuation of hyperviscosity, modifications of circulating immune complexes, elimination of toxic antibodies and protein bound toxins). Component separation represents a step forward to supportive treatment and immunological reconstitution.

Antigen-Antibody Complex↗
PubMedDate not supplied

[Father-child hospitalization in the separation anxiety].

Severe forms of separation anxiety disorder with school refusal can be difficult to treat: on the one hand the resistance to outpatient treatment is usual, on the other hand, fear of separation is so overwhelming that hospitalization can be seen as too dramatic. We suggest hospitalizing the child with his or her father as fear of separation with the mother is usually the main problem. We report a case study of a 13 year old child with separation anxiety disorder who refused to go to school and to be separated from his mother. Treatment consisted of hospitalizing the child with his father and to gradually restore his autonomy. The father was given the role of a co-therapist: the main therapeutic decisions about graduated exposure to separation were taken after discussion with the father who passed them on to the child. These structuring interventions re-established the father's control which helped to sedate the child's anxiety.

Adolescent↗
PubMed1994

In vitro separation of embryonic chick skeletal muscle myoblasts and fibroblasts: comparison of their characteristics.

The aim of the present experiments was to test two methods of separating myoblasts and fibroblasts (selective plating, differential trypsinization) from chick embryonal skeletal muscle and to compare their characteristics. Ornithine decarboxylase (ODC) activity, the amount of incorporated [3H]leucine into proteins and incorporation of [3H]thymidine into DNA were significantly higher in myoblasts than in fibroblasts separated by selective plating. When comparing myoblasts and fibroblasts separated by differential trypsinization, significantly higher ODC activity and greater incorporation of [3H]leucine into protein, but no incorporation of [3H]thymidine into DNA, were found in myoblasts. Higher ODC activity and greater incorporation of labelled leucine were found in fibroblasts separated by the selective plating than in fibroblasts separated by differential trypsinization. The incorporation of labelled thymidine into DNA was higher in myoblasts separated by selective plating than in myoblasts obtained by differential trypsinization. The method of selective plating appears to be simpler and adequate for obtaining myoblastic and fibroblastic cell cultures with sufficiently low mutual contamination. The method of differential trypsinization involves a more drastic treatment of cells and is more time consuming.

Animals↗
PubMed1996

Immunomagnetic separation can enrich fixed solid tumors for epithelial cells.

Immunomagnetic separation is a highly specific technique for the enrichment or isolation of cells from a variety of fresh tissues and microorganisms or molecules from suspensions. Because new techniques for molecular analysis of solid tumors are now applicable to fixed tissue but sometimes require or benefit from enrichment for tumor cells, we tested the efficacy of immunomagnetic separation for enriching fixed solid tumors for malignant epithelial cells. We applied it to two different tumors and fixation methods to separate neoplastic from non-neoplastic cells in primary colorectal cancers and metastatic breast cancers, and were able to enrich to a high degree of purity. Immunomagnetic separation was effective in unembedded fixed tissue as well as fixed paraffin-embedded tissue. The magnetically separated cells were amenable to fluorescence in situ hybridization and polymerase chain reaction amplification of their DNA with minimal additional manipulation. The high degree of enrichment achieved before amplification contributed to interpretation of loss of heterozygosity in metastatic breast cancers, and simplified fluorescence in situ hybridization analysis because only neoplastic cells were hybridized and counted. Immunomagnetic separation is effective for the enrichment of fixed solid tumors, can be performed with widely available commercial antibodies, and requires little specialized instrumentation. It can contribute to interpretation of results in situations where enrichment by other methods is difficult or not possible.

Breast Neoplasms↗
PubMed1999

Protein formulation and lyophilization cycle design: prevention of damage due to freeze-concentration induced phase separation.

Hemoglobin has been previously shown to unfold during freeze drying when lyophilized from formulations that undergo freeze-concentration induced phase separation (Heller et al. 1997. Biotechnol Prog 13:590-596). In this report, we show that such damage may be avoided using kinetic strategies to arrest the phase separation. By rapidly cooling samples during liquid nitrogen spray-freeze drying, the time that the formulation spends in temperature regimes (ca. -3 to -23 degrees C) in which phase separation is both thermodynamically favorable and kinetically realizable is minimized. Increased protein damage with decreasing cooling rates and/or longer annealing periods at -7 degrees C is observed by FTIR spectroscopy. Phase separation and concomitant protein damage may also be avoided by addition of mannitol at concentrations sufficient to cause crystallization. Mannitol crystals segregate the freeze concentrated solution into microscopic domains that block propagation and nucleation of phase separating events. Addition of noncrystallizing sugars, such as sucrose and trehalose, or nonionic surfactants, such as Tween 80 and Triton X-100, has little protective effect against phase separation induced damage during freezing drying.

Calorimetry, Differential Scanning↗
PubMedDate not supplied

Continuous separation of serum proteins using a stirred cell charged with carboxylated and sulfonated microspheres.

We contrived a new separation system using a stirred cell charged with uncoupled microsphere similar to the chromatographic separation. Microspheres, carboxylated PS/PMAA and sulfonated PS/PNaSS, were prepared by emulsifier-free emulsion polymerization. To complement the submicron size weakness and the absence of ligands, we employed the latex form, the dispersion of microsphere, and took advantage of interaction relationships between proteins and microspheres. Adsorption isotherm is contemplated to investigate continuous separation behaviours of serum proteins. Selectivity of separation is in the following order: PS/PNaSS-2.0 (high sulfonated) < PS/PNaSS-0.3 (low sulfonated) < PS/PMAA-0.5 (low carboxylated). Unlike previous works on batch separation, not only the adsorbed amount in equilibrium (Cm), but also adsorption coefficient (K), played an important role in continuous separation. Functional groups (carboxyl and sulfonate), induced from the co-monomer, also affected the adsorption behaviours.

Adsorption↗
PubMed1999

Highly efficient separation of isomeric epoxy fatty acids by micellar electrokinetic chromatography.

A capillary electrophoresis (CE) method has been developed for simple and direct separation of cis- and trans-12,13-epoxy-9(Z)-octadecenoic acid and 9,10-epoxy-12(Z)-octadecenoic acid isomers. Separation was performed in micellar electrokinetic capillary chromatography (MEKC) using a buffer consisting of 25 mM borate (pH 9.20), 10 mM sodium dodecyl sulfate (SDS) and 10% v/v acetonitrile. The key variables, concentrations of SDS and organic modifier, were optimized by the application of a factorial experimental design. The use of a low micellar concentration, just above critical micelle concentration (CMC), in a background electrolyte containing an organic modifier not only made it possible to dissolve and separate highly hydrophobic fatty acid isomers, but also resulted in improved separation efficiency and selectivity. Separation efficiency up to 4 x 10(5) theoretical plates/m was achieved under an optimized condition. Also investigated were the influence of temperature on separation and the effect of organic modifier concentration on the dynamic exchange of the analytes between micelles and the bulk of the buffer solution. Direct UV was applied for detection of the fatty acids.

Chromatography, Micellar Electrokinetic Capillary↗
PubMed1999

Separations of enantiomers by preparative capillary isotachophoresis.

The use of capillary isotachophoresis (ITP), operating in a discontinuous fractionation mode, for preparative separations of enantiomers of chiral compounds was studied. The ITP separations were carried out in the column-coupling configuration of the separation unit provided with the preseparation column of a 1.0 mm ID and the trapping column of a 0.8 mm ID. Such a configuration of the CE separation unit offers several working regimes suitable to preparative separations of enantiomers. 2,4-Dinitrophenyl-DL-norleucine (DNP-Norleu) was employed as a model analyte in our experiments with beta-cyclodextrin serving in the electrolyte solutions as a chiral selector. The preparative separations lasting about 20 min were evaluated by ITP and (more often) by capillary zone electrophoresis (CZE). It was found that one preparative run provided up to 14 microg of pure DNP-Norleu enantiomers. This corresponded to a 75 times higher production rate of ITP relative to a maximum value of this parameter as estimated for preparative CZE runs in cylindrical capillaries (0.5 pmol/s). About 75% of the DNP-Norleu enantiomers loaded into the preparative equipment could be recovered in pure enantiomer fractions. Contiguous natures of the zones in the ITP stack and adsorption losses of the enantiomers in the isolation step were found to set practical limits for a further enhancement of the recovery rates in the isolation of pure enantiomers.

Electrophoresis, Capillary↗
PubMed1999

Selectivity in capillary electrokinetic separations.

This review gives a survey of selectivity modes in capillary electrophoresis separations in pharmaceutical analysis and bioanalysis. Despite the high efficiencies of these separation techniques, good selectivity is required to allow quantitation or identification of a particular analyte. Selectivity in capillary electrophoresis is defined and described for different separation mechanisms, which are divided into two major areas: (i) capillary zone electrophoresis and (ii) electrokinetic chromatography. The first area describes aqueous (with or without organic modifiers) and nonaqueous modes. The second area discusses all capillary electrophoretic separation modes in which interaction with a (pseudo)stationary phase results in a change in migration rate of the analytes. These can be divided in micellar electrokinetic chromatography and capillary electrochromatography. The latter category can range from fully packed capillaries, via open-tubular coated capillaries to the addition of microparticles with multiple or single binding sites. Furthermore, an attempt is made to differentiate between methods in which molecular recognition plays a predominant role and methods in which the selectivity depends on overall differences in physicochemical properties between the analytes. The calculation of the resolution for the different separation modes and the requirements for qualitative and quantitative analysis are discussed. It is anticipated that selectivity tuning is easier in separation modes in which molecular recognition plays a role. However, sufficient attention needs to be paid to the efficiency of the system in that it not only affects resolution but also detectability of the analyte of interest.

Electrophoresis, Capillary↗
PubMed2000

Fast separation of oligonucleotide and triplet repeat DNA on a microfabricated capillary electrophoresis device and capillary electrophoresis.

A laser-induced fluorescence detection system coupled with a highly sensitive silicon-intensified target (SIT) camera is successfully applied to the imaging of a band for DNA fragment labeling by fluorescence dye in a microchannel, and to the visualizing of the separation process on a microfabricated chip. We demonstrated that an only 6 mm separation channel is sufficient for the separation of triplet repeat DNA fragment and DNA molecular marker within only 12 s. The separation using the microfabricated capillary electrophoresis device is confirmed to be at least 18 times faster than the same separation carried out by conventional capillary electrophoresis with 24.5 cm effective length. The use of a short capillary with 8.5 cm effective length is also efficient for fast separation of DNA; however, the microchip technology is even faster than capillary electrophoresis using a short capillary.

DNA↗
PubMed2000

Ultrathin-layer sodium dodecyl sulfate gel electrophoresis of proteins: effects of gel composition and temperature on the separation of sodium dodecyl sulfate-protein complexes.

This paper discusses the effects of gel composition and separation temperature on the migration properties of fluorescein-5-isothiocyanate-labeled protein molecular mass markers (ranging from 20 100 to 205 000 Da) in automated ultrathin-layer sodium dodecyl sulfate (SDS) gel electrophoresis. The separation mechanism with the agarose and composite agarose - linear polyacrylamide, agarose - hydroxyethyl cellulose, and agarose - polyethylene oxide matrices were all found to comply with the Ogston sieving model in the molecular mass range of the protein molecules investigated. Our temperature studies revealed that electrophoretic separation of SDS protein complexes is an activated process and, in pure agarose and in composite agarose hydroxyethyl cellulose and agarose - polyethylene oxide matrices that the separation requires increasing activation energy as a function of the molecular mass of the separated proteins. On the other hand, when linear polyacrylamide was used as composite additive, the activation energy demand of the separation decreased with increasing solute molecular mass. The sensitivity of the laser-induced fluorescent detection of the automated ultrathin-layer electrophoresis system was evaluated by injecting a series of dilutions of the markers and was found to be less than 2.5 ng/band for the fluorophore-labeled protein.

Chemical Phenomena↗
PubMed2001

Separation of divinyl ether fatty acid isomers by micellar electrokinetic chromatography.

A micellar electrokinetic chromatography (MEKC) method has been developed for the direct resolution of divinyl ether type of hydrophobic fatty acid isomers. The fatty acid isomers resolved include colneleic acid (CL), colnelenic acid (CLn), 14(Z)-etheroleic acid (14(Z)-EL), 14(Z)-etherolenic acid (14(Z)-Eln), 11(Z)-etheroleic acid (11(Z)-EL), 11(Z)-etherolenic acid (11(Z)-Eln), etheroleic acid (EL) and etherolenic acid (Eln). These fatty acid isomers differ in number, position and spatial arrangement of the double bonds and the position of the ether oxygen. A central composite design was employed for the optimization of the key variables of the separation, namely the concentrations of sodium dodecyl sulfate (SDS) and organic modifiers. The use of micelles combined with an organic modifier in the background electrolyte made it possible to dissolve and separate relatively hydrophobic fatty acid isomers, and to achieve high separation efficiency. Using heptakis-(2,3-dimethyl-6-sulfato)-beta-cyclodextrin (HDMS-beta-CD) as a buffer additive, complete separation of the examined eight divinyl ethers was achieved. Separation efficiencies up to 5 x 10(5) theoretical plates/m were achieved under optimized conditions. Direct UV was applied for detection of the fatty acids. The results were compared with those obtained from high-performance liquid chromatography (HPLC) separation.

Buffers↗