PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Separation”

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
PubMed1992

Improvement of the separation of blood by modification of separators Optipress and Biotrans Separator.

UNLABELLED: By use of the new top-and-bottom bag system and automatic separators the quality of red cell concentrates (RCC) and fresh frozen plasma (FFP) could be markedly improved. Simultaneous preparation of storable single-donor platelet concentrates (PC) resulted, however, in too high losses of red cells and plasma. Through modification of the pressure plate of the separators and variation of the residual buffy coat (BC) volumes we tried to optimize the separation in this respect. In a second study we tried to establish the preparation of platelet-rich plasma (PRP) using top-and-bottom bag systems and automatic separators. MATERIALS AND METHODS: 1st study: 149 whole-blood units (Biopack U, quadruple systems) were separated into components either with Optipress (Opt, n = 58) or with Biotrans Separator (Bio, n = 91). To Optipress additional plates, 3-6 mm thick, were attached and the residual BC volume was varied by different adjustments of the distance screw. The Biotrans Separator was used with a plane pressure plate as well as with a modified plate having a transverse groove; the residual BC volume was adjusted to 50-120 ml. 2nd study: 15 whole-blood units were separated into PRP and RCC either using the Optipress (standard version, n = 5) or the Biotrans Separator (alternating opening of clamps, standard plate, n = 10). RESULTS AND CONCLUSIONS: 1st study: Both separations could be improved. The loss of red cells was significantly lower in case of the Biotrans Separator: Bio 15.6%, Opt 25.9%, p < 0.001. Other separation parameters showed no relevant difference between both separators. 2nd study: By use of the Biotrans Separator significantly less platelets could be separated (Bio 75.1 x 10(9), Opt 87.0 x 10(9), p < 0.05), but the PRP clearly was contaminated with less leukocytes (Bio 51.0 x 10(6), Opt 458.9 x 10(6), p < 0.01). The contamination of the RCC with leukocytes (about 20%) was markedly improved in both methods when compared with conventional preparations. The mean loss of red cells was 12.8% in both methods.

Blood Component Removal↗
PubMedDate not supplied

Homologous human blood protein separation using immobilized metal affinity chromatography: protein C separation from prothrombin with application to the separation of factor IX and prothrombin.

Protein C (PC) is a natural anticoagulant and antithrombotic present in human blood at a concentration of 4 microg/mL. Its deficiency can result in excessive clotting and thrombosis. Protein C can be obtained from human blood plasma; however, there are other coagulant proteins in blood, including prothrombin (factor II), which is present in relatively large amounts and is one of the most active components. Protein C and prothrombin are homologous proteins with similar biochemical features; therefore, immunoaffinity chromatography is used for their separation. However, this technology is very expensive, protein C recovery and activity is low, and contamination problems with mouse antibody are likely. Immobilized metal affinity chromatography (IMAC) utilizes the protein metal-binding properties for protein separation. Protein C has twelve surface-accessible histidines, which are the major metal-binding groups for IMAC separation. After investigating metal ion-binding properties of protein C, we used an IDA-Cu column to separate protein C and prothrombin. Following protein adsorption to the column, prothrombin was washed out using a sodium phosphate buffer containing 2 mM imidazole and protein C was recovered with 15 mM imidazole in the buffer. The mild elution condition allows a high protein C activity and a high recovery. Also, this technology introduces no immunoglobulins, and it is relatively inexpensive. IMAC could replace the immunoaffinity technology for the large-scale separation of protein C from blood plasma Cohn Fraction IV-1. In addition, this work demonstrates a significant application of this technology for the separation of factor IX from prothrombin. Prothrombin has proven to be a harmful contaminant in factor IX cocktails that have been administered to humans in the treatment of hemophilia B.

Blood Proteins↗
PubMed2001

Effects of early separation on the dairy cow and calf: 2. Separation at 1 day and 2 weeks after birth.

This study investigated the effects of separating dairy calves from their mothers at 1 day (early separation) and 14 days (late separation) after birth. Behavioural observations were conducted on 24 Holstein dairy cow-calf pairs during the first 24h after separation. Before separation, cow-calf pairs were generally inactive. After separation, cows from the late-separation treatment group showed higher rates of calling, movement and placing the head outside the pen, than cows in the early-separation group. Parity did not influence cow behaviour. During the first 2 weeks after calving, cows in the late-separation group (i.e. still with their calves) yielded less milk at milking, a difference at least partly due to the milk consumed by the calf. Milk yields from days 15-150 did not differ between the two groups. After separation, calves in the late-separation group moved and placed their heads outside the pen more often than early-separation calves. During the first 14 days after birth, late-separation calves gained weight at more than three times the rate of those separated early. When introduced to an unfamiliar calf at 6 weeks of age, calves from the late-separation group showed more intense social behaviour towards the unfamiliar calf than did those calves separated early. Thus, the response to separation by both cows and calves increased when calves were separated at 2 weeks rather than 1 day of age, but calves separated at the later age gained more weight and delayed separation appeared to influence the development of calf social behaviour.

Journal Article↗
PubMed2000

Effects of early separation on the dairy cow and calf. 1. Separation at 6 h, 1 day and 4 days after birth.

The aim of this study was to evaluate the effects of age of separation on the behavioural responses of the dairy calf and cow. Calves were separated from their dams 6 h, 1 day, or 4 days after birth (n=9 cow-calf pairs in each of the 3 treatment groups) and behaviour was video and audio taped from 1 h before separation to 21 h after separation. In the hour immediately before separation, we found that the younger calves tended to call and move more in the pen, and spent more time standing than the older calves, but after separation these trends reversed. Calves separated at older ages made significantly more movements in the pen (P<0.05), spent more time standing (P<0.05) and spent more time with the head out of the pen (P<0.01) than calves separated soon after birth. We observed a similar pattern for the cows. Before separation, cows with younger calves moved more frequently about the pen (P<0.05), and called at much higher rates (a mean of 40.7 calls during 40 min for cows on the 6-h treatment, vs. 0.2 calls for cows in the 4-day group; P<0.001). After separation, cows in the 4-day group called at approximately four times the rate of those separated at 6 h or 1 day (P<0.01). Moreover, the calls produced by cows separated later had a significantly higher fundamental frequency (P<0.001) and a lower emphasized harmonic (P<0.02) than the calls of cows separated from calves soon after birth. There was no difference between treatment groups in the other behavioural measures, either before or after separation. Calves separated at older ages tended to require fewer days of treatment for scouring, but calf weight gain and cow milk production did not differ among treatment groups. In conclusion, behavioural responses of both the cow and calf increase in relation to calf age at separation. However, there may be health advantages associated with delayed separation that compensate for the increased behavioural response.

Journal Article↗
PubMed2000

Capillary electrophoresis separations on a planar chip with the column-coupling configuration of the separation channels

Some basic aspects of capillary electrophoresis (CE) separations on a poly(methyl methacrylate) chip provided with two separation channels in the column-coupling (CC) configuration and on-column conductivity detectors were studied. The CE methods employed in this study included isotachophoresis (ITP), capillary zone electrophoresis (CZE), and CZE with on-line ITP sample pretreatment (ITP-CZE). Hydrodynamic and electroosmotic flows of the solution in the separation compartment of the chip were suppressed, and electrophoresis was a dominant transport process in the separations performed by these methods. Very reproducible migration velocities of the separated constituents were typical under such transport conditions, and consequently, test analytes could be quantified by various ITP techniques with 1-2% RSD. The CC configuration of the separation channels provides means for an effective combination of an enhanced load capacity of the separation system with high detection sensitivities for the analytes in concentration-cascade ITP separations. In this way, for example, succinate, acetate, and benzoate could be separated also in instances when they were present in the loaded sample (1.2 microL) at 1 mmol/L concentrations while their limits of detection ranged from 8 to 12 micromol/L concentrations. A well-defined ITP concentration of the analyte(s) combined with an in-column sample cleanup (via an electrophoretically driven removal of the matrix constituents from the separation compartment) can be integrated into the separations performed on the CC chip. These sample pretreatment capabilities were investigated in ITP-CZE separations of model samples in which nitrite, phosphate, and fluoride (each at a 10 micromol/L concentration) accompanied matrix constituents (sulfate and chloride) at considerably higher concentrations. Here, both the concentration of the analytes and cleanup of the sample were included in the ITP separation in the first separation channel while the second separation channel served for the CZE separation of the ITP pretreated sample and the detection of the analytes.

Journal Article↗
PubMed1990

[Frequency of fused roots, divergent separation, convergent separation, rectilinear separation and delaceration of third molars].

In a sample of Brazilian white young adults between 18-23 years old, the A.A. studied the third molar roots, in anatomical aspects, using the orthopantomographic radiographic method. They concluded that the superior third molar shows a biggest number of fusionated roots (19.50% in the right side and 19.66% in the left side) and the inferior third molar shows a biggest number of separated roots (21.48% in the right side and 19.66% in the left side).

Adult↗
PubMed1990

Two mechanisms for localization? Evidence for separation-dependent and separation-independent processing of position information.

The Weber function for separation--i.e. delta s as a function of separation s--is typically measured using a pair of targets presented roughly symmetrically relative to the fovea. With this paradigm, as the separation increases, the eccentricity of the individual targets increases also. To disentangle the effects of separation and eccentricity on the Weber function for separation, we systematically examined each of these variables and also examined the effects of target size and exposure duration. Separation discrimination thresholds were measured for average separations from 3 to 6 deg across a wide range of eccentricities, and for eccentricities of 2.5-10 deg for a range of separations. The dependence of threshold on target size was measured by varying the length of the stimuli from 1 to 120 min arc; the dependence on exposure duration was measured using durations of 100 and 500 msec at 10 deg eccentricity for comparison with data collected previously at smaller eccentricities. We found that for separations less than the eccentricity of the targets, thresholds depend primarily on separation; for larger separations, thresholds depend solely on eccentricity. In general, unless the targets are very small or quite brief, the spatial and temporal characteristics of the targets are not major contributors to the slope of the Weber function. Two mechanisms are proposed to account for thresholds in the two regions, one separation-dependent and one separation-independent.

Differential Threshold↗
PubMed1999

Separation of double-stranded DNA fragments in plastic capillary electrophoresis chips by using E99P69E99 as separation medium.

The separation of double-stranded DNA (dsDNA) fragments in polymethylmethacrylate (PMMA) capillary electrophoresis (CE) chips by using E99P69E99 as a separation medium has been demonstrated. The PMMA CE chips were simply manufactured by micromachining and adhesive tape sealing. To make the separation channel compatible with the separation medium, a dynamic nonionic surfactant coating procedure was developed, which made the plastic separation channel sufficiently hydrophilic to allow the separation medium to fill the channel by capillary action. Subsequent separation of DNA fragments was successful with a separation efficiency of the order of 10(4) theoretical plates over an effective separation distance of 1.5 cm. By using an applied electric field strength of 200 V/cm, the separation of low DNA mass ladder was completed within 5 min. The simple coating procedure, together with the self-assembled viscosity-adjustable separation medium, should be useful to meet some of the essential requirements for developing single-use disposable CE chips. Coating the channels with polymer blends of PMMA and the separation medium also showed promise.

Animals↗
PubMed1997

Redefining the separation factor: a potential pathway to a unified separation science.

Understanding the separation process in capillary electrophoresis (CE) leads to the unification of the theories for separation science. While the separation of analytes is governed by equilibria in chromatography, and by (centrifugal) field in ultracentrifugation, the separation in CE is governed by both equilibria and (electric) field. Therefore, a comprehensive separation theory that describes the separation process of analytes in CE should be able to describe the separation processes in both chromatography and ultracentrifugation. In this paper, we propose that individual capacity factors for each analyte species be used to describe the migration behavior of an analyte. The effect of field on each analyte species, as well as the effect of equilibria are considered in deriving a generalized equation that is applicable for all separation techniques. The separation factor defined at present does not directly relate to the migration rates of the analytes, and therefore can not be used in a generalized theory. We propose that the ratio of the migration rates of a pair of analytes (gamma) should be used as the separation factor, instead of the ratio of the two capacity factors. When gamma is used to describe the separation of two closely migrating analytes, all separation techniques have the same resolution equation.

Chromatography↗
PubMed2001

Separation anxiety and actual separation experiences during childhood in patients with panic disorder.

OBJECTIVE: The association between separation anxiety in childhood and actual separation experiences during childhood has not yet been investigated in patients with panic disorder. METHODS: In 115 patients with panic disorder with or without agoraphobia and in 124 control subjects without a history of psychiatric illness, we assessed separation anxiety during childhood, retrospectively, using DSM-IV and ICD-10 criteria and the Separation Anxiety Symptom Inventory (SASI). In addition, actual separation experiences from age 0 to 15 years were assessed, retrospectively. RESULTS: A total of 22.6% of the patients and 4.8% of the control subjects fulfilled both DSM-IV and ICD-10 criteria for childhood separation anxiety (chi 2 = 11.8; P < 0.0001). Further, 57.4% of the patients and 37.9% of the control subjects reported actual separation experiences during their childhood (chi 2 = 9.09, P < 0.003). Separation anxiety and actual separation experiences, however, were independent of each other. CONCLUSION: These results suggest that separation anxiety during childhood is not a consequence of actual traumatic separation experiences in panic disorder patients.

Adolescent↗
PubMed1981

Preparative nonlytic separation of Lyt2+ and Lyt2- T lymphocytes, functional analyses of the separated cells and demonstration of synergy in graft-vs.-host reaction of Lyt2+ and Lyt2- cells.

A convenient, preparative scale, nonlytic separation of mouse T lymphocytes into Lyt2.2+ and Lyt2.2- populations is reported. Immunoglobulin-negative (Ig-) spleen cells, Ig- lymph node cells, and peanut lectin-unagglutinated (PNA-) thymocytes were incubated under sterile conditions at 0 degree C with monoclonal mouse antibody to the Lyt2.2 T cell differentiation antigen. The antibody-treated cells were washed and placed in polystyrene tissue culture dishes that had been precoated with antibody to mouse Ig. Nonadherent populations were depleted to Lyt2.2+ cells and were essentially devoid of cytotoxic T lymphocyte precursors (CTLp), but contained helper activity for in vivo T-dependent IgM, IgG and IgA antibody formation. Adherent cell populations were enriched for Lyt2.2+ cells and for CTLp. The graft-vs.-host activity of the separated, adherent (Lyt2.2+) and nonadherent (Lyt2.2-) cells in the Simonsen spleen assay in neonatal (C57BL/6 x BALB/c)F1 mice was less than of unfractionated cells, but the activity of remixed Lyt2.2+ plus Lyt2.2- cells was higher than the sum of the contributions of these cells tested separately, and equal to that of the unfractionated cells. PNA- thymocytes were also separated into Ly2.2+ and Lyt2.2- populations by fluorescence-activated cell sorting. Nonlytic separation allows the recovery of the Lyt1+2+ population, which is lost in cytotoxic elimination experiments. Under the conditions described for the plate separation, the purity of the separated cells and recovery of activity approaches that of cells separated by sorting. Therefore, the plate separation offers a convenient alternative to fluorescence-activated cell sorting when large numbers (i.e. up to 5 x 10(7) positively selected cells) are needed, as in studies of in vivo cell-mediated immune reactions.

Animals↗
PubMed1990

[Comparison of thrombocyte concentrates of the cell separator AS 104 with preparations of the cell separator CS 3000 (Fenwal)].

Platelet concentrates of the cell separator AS 104 (Fresenius) are compared with those of the cell separator CS 3000 (Fenwal). At each cell separator two platelet preparation protocols and at CS 3000 additionally a WBC preparation protocol was analysed. Platelet counts before and after cellapheresis as well as separation efficiencies show no significant differences between the separation protocols (A, B) and the two cell separators. Platelets of varying volumes show different separation efficiencies. While in WBC concentrates the separation efficiencies of platelets continuously increase from small (2fl) to large (20 fl) platelets, the efficiencies in platelet concentrates decrease in volume range 2 fl-8 fl, and increase in range 8 fl-20 fl. There are no differences between the cell separators. The efficiencies of platelets with 2 fl and 4 fl volumes differ significantly (p less than 0.001) between the protocols A and B of AS 104. After WBC-donation, platelet loss of donors corresponds with platelet yields of the concentrates for the platelet volume range 2 fl-20 fl. Compared with the calculated platelet loss of donors after platelet donation more small platelets with 2 fl-8 fl volumes are found in platelet concentrates. The yields of platelets with 10 fl-20 fl volumes are in accordance with donor's platelet loss.

Blood Transfusion↗
PubMed2001

Isotachophoresis and isotachophoresis--zone electrophoresis separations of inorganic anions present in water samples on a planar chip with column-coupling separation channels and conductivity detection.

The use of a poly(methylmethacrylate) chip, provided with two separation channels in the column-coupling (CC) arrangement and on-column conductivity detection sensors, to electrophoretic separations of a group of inorganic anions (chloride, nitrate, sulfate, nitrite, fluoride and phosphate) that need to be monitored in various environmental matrices was studied. The electrophoretic methods employed in this study included isotachophoresis (ITP) and capillary zone electrophoresis (CZE) with on-line coupled ITP sample pretreatment (ITP-CZE). Hydrodynamic and electroosmotic flows of the solution in the separation compartment of the CC chip were suppressed and electrophoresis was a dominant transport process in the separations performed by these methods. ITP separations on the chip provided rapid resolutions of sub-nmol amounts of the complete group of the studied anions and made possible rapid separations and reproducible quantitations of macroconstituents currently present in water samples (chloride, nitrate and sulfate). However, concentration limits of detection attainable under the employed ITP separating conditions (2-3 x 10(-5) mol/l) were not sufficient for the detection of typical anionic microconstituents in water samples (nitrite, fluoride and phosphate). On the other hand, these anions could be detected at 5-7 x 10(-7) mol/l concentrations by the conductivity detector in the CZE stage of the ITP-CZE combination on the CC chip. A sample clean-up performed in the ITP stage of the combination effectively complemented such a detection sensitivity and nitrite, fluoride and phosphate could be reproducibly quantified also in samples containing the macroconstituents at 10(4) higher concentrations. ITP-CZE analyses of tap, mineral and river water samples showed that the CC chip offers means for rapid and reproducible procedures to the determination of these anions in water (4-6 min analysis times under our working conditions). Here, the ITP sample pretreatment concentrated the analytes and removed nanomol amounts of the macroconstituents from the separation compartment of the chip within 3-4 min. Both the ITP and ITP-CZE procedures required no or only minimum manipulations with water samples before their analyses on the chip. For example, tap water samples were analyzed directly while a short degassing of mineral water (to prevent bubble formation during the separation) and filtration of river water samples (to remove particulates and colloids) were the only operations needed in this respect.

Electrochemistry↗
PubMed2001

Effects of antibody concentration on the separation of human natural killer cells in a commercial immunomagnetic separation system.

BACKGROUND: The magnetic separation of a cell population based on cell surface markers is a critical step in many biological and clinical laboratories. In this study, the effect of antibody concentration on the separation of human natural killer cells in a commercial, immunomagnetic cell separation system was investigated. METHODS: Specifically, the degree of saturation of antibody binding sites using a two-step antibody sandwich was quantified. The quantification of the first step, a primary anti-CD56-PE antibody, was achieved through fluorescence intensity measurements using a flow cytometer. The quantification of the second step, an anti-PE-microbeads antibody reagent, was achieved through magnetophoretic mobility measurements using cell tracking velocimetry. RESULTS: From the results of these studies, two different labeling protocols were used to separate CD56+ cells from human, peripheral blood by a Miltenyi Biotech MiniMACS cell separation system. The first of these two labeling protocols was based on company recommendations, whereas the second was based on the results of the saturation studies. The results from these studies demonstrate that the magnetophoretic mobility is a function of both primary and secondary antibody concentrations and that mobility does have an effect on the performance of the separation system. CONCLUSIONS: As the mobility increased due to an increase in bound antibodies, the positive cells were almost completely eliminated from the negative eluent. However, with an increase in bound antibodies, and thus mobility, the total amount of positive cells recovered decreases. It is speculated that these cells are irreversibly retained in the column. These results demonstrate the complexity of immunomagnetic cell separation and the need to further optimize the cell separation process.

Antigen-Antibody Reactions↗
PubMed1979

Separation of functional subpopulations of murine and human lymphoid cells on colloidal silica density gradients. I. Preparation of the Ludox AM gradient material and characterization of separation capacities.

This report describes a unique modification of an isopycnic density gradient system utilizing as a separating menstrum colloidal silica (Ludox AM). The primary advantages of this preparation are: (1) It is chemically defined, allowing extremely reproducible cell separation employing different lots of material; (2) the physical parameters (pH, density, salt concentration) of the final gradient suspension can be manipulated over a wide range of values, allowing for the separation of many different biological materials; (3) it allows separation of very large numbers of lymphoid cells with greater than 95% recovery of applied cells; (4) separated cellular subpopulations can be easily washed free of silica and cellular function is retained. This paper is a report of the preparation and functional characteristics of the gradient material as it relates to the separation of very large numbers of lymphoid cell subpopulations in both mouse and man. Subpopulations of murine and human lymphocytes separated by this gradient material were assayed for IgM synthesis, T-cell mediated cytotoxicity, and lymphokine production.

Animals↗
PubMed1980

Separation of blood cells from normal blood and blood of patients with various malignant blood diseases using separation media.

Differential counts of normal and leukemic cells separated from human peripheral blood were compared using three different separation media a) Verografin, b) Verografin-Ficoll, c) Isopaque-Ficoll (Lymphoprep), density 1.077 g/ml. In the separation the solution of Verografin (SPOFA) or Verografin-Ficoll yields analogous cell counts to Isopaque-Ficoll solution. The separation of leukemic cells is similar on all three separation media with considerable packing of some cells of the myeloid line. The blood cells separated from peripheral blood of normal donors on three various separation media correlate also in T and B lymphocyte counts, as demonstrated by the results of E and EAC rosette tests.

Cell Separation↗
PubMed2001

Separation selectivity patterns in the capillary electrophoretic separation of anionic enantiomers by octakis-6-sulfato-gamma-cyclodextrin.

The capillary electrophoretic separation of anionic enantiomers with multiply-charged, single-isomer, anionic resolving agents was reexamined with the help of the charged resolving agent migration model. Three general model parameters were identified that influence the shape of the separation selectivity and enantiomer mobility difference curves: parameter b, the binding selectivity (K(RCD)/K(SCD)), parameter s, the size selectivity (micro0RCD/micro0SCD), and parameter a, the complexation-induced alteration of the analyte's mobility (micro0SCD/micro0). Function analysis of the model indicates that there are six unique separation selectivity vs. resolving agent concentration patterns: in two of the patterns, separation selectivity asymptotically increases to the limiting value set by parameter b; in two other patterns, separation selectivity passes a local maximum and asymptotically decreases to the limiting value set by parameter b; and in the last two patterns, separation selectivity passes a local maximum, decreases to unity, then, after reversal of the intrinsic migration order, asymptotically increases to the limiting value set by parameter b. Though the patterns with asymptotically increasing selectivities were observed in earlier work, this paper reports the first experimental verification of the existence of the local selectivity maximum during the capillary electrophoretic separation of the enantiomers of several weak acids in high pH background electrolytes with octakis-6-sulfato-gamma-cyclodextrin as the resolving agent.

Cyclodextrins↗