Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Separation”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 163 records · Page 9Linked to original sources
PubMed1985

Separation and quantitation of insulins and related substances in bulk insulin crystals and in injectables by reversed-phase high performance liquid chromatography and the effect of temperature on the separation.

The Food and Drug Administration performs potency assays of insulin products as part of the insulin certification program required by the Code of Federal Regulations. The official method specified in the United States Pharmacopeia (USP) is a bioassay measuring the depression of blood sugar concentrations in rabbits treated with the insulin under test and the official standard. The insulin products resulting from today's technology include highly purified isolates from bovine or porcine pancreas and insulin that is identical in structure to human insulin. A study of the effects of temperature on the separation of the components in insulin injectables led to the development of a reversed-phase high performance liquid chromatographic (HPLC) method that uses a sulfate buffer/acetonitrile mobile phase at 40 degrees C for the separation and quantitation of bovine, porcine, and human insulins and related substances. This HPLC method reduces analysis time to 1/60 of that required for the bioassay and yields more information about purity than the percent nitrogen determination that is one of the USP official procedures. The results of HPLC analyses were compared with those for the bioassay by means of a potency/area conversion factor computed on a species by species basis. Results for the bioassays and the HPLC determinations for 40 lots of bulk crystalline insulin were compared in this study; in general, the HPLC estimates fell within the 95% confidence interval for combined independent bioassays.

Animals↗
PubMed1977

Separation of two Salmonella O-antigen polysaccharides by means of a glutaraldehyde-concanavalin-A polymer. Primary studies on the separated fractions.

The Salmonella zuerich (1,9,12,(46),27) cell wall O-polysaccharides have been characterized as a mixture of two immunologically distinct fractions differing in the presence or absence of the antigenic determinant 1 usually carried by side chains of an alpha-D-glucosyl residue. In this paper, we describe the use of concanavalin A in separating the two O-polysaccharides. The procedure involves polymerization of concanavalin A with glutaraldehyde, followed by selective adsorption of the polysaccharide containing O factor 1 and elution with D-glucose. Immunological and chemical analyses showed that the separation was successful and demonstrated chemical differences between these two fractions in relation to their immunological behaviour.

Animals↗
PubMed1980

Demonstration of separate receptors for human IgA and IgG in group A streptococci type 4. Separation of the solubilized receptors from group- and type-specific antigens, lipoteichoic acid and peptidoglycan.

The alkaline extract of group A streptococci type 4 was separated by electrophoresis and diffused against 27 normal human sera. One of the precipitates appeared with 85% of the sear. Addition of purified IgA myeloma protein or sera containing IgA M-components to the extract changed the electrophoretic mobility of the precipitate anodically. Purified IgG Fc-fragments or sera containing IgG M-component did not affect the mobility of the precipitate. It was concluded that this precipitate contained the streptococcal receptor for human IgA. A non-precipitating IgG Fc-receptor, with agglutinating capacity for cells coated with human IgG1 but not IgG3, was localized by preparative electrophoresis to the same electrophoretic region as the IgA receptor. The mobility of the IgG receptor remained unaltered on addition of IgA myeloma protein permitting a separation of the two receptors by preparative electrophoresis. The receptors were distinct from the group specific carbohydrate, peptidoglycan and lipoteicholic acid. No M antigen or opacity factor were demonstrated in the extract.

Antigens, Viral↗
PubMed2006

Rapid separation and counting of viable microbial cells in food by nonculture method with bioplorer, a focusing-free microscopic apparatus with a novel cell separation unit.

A nonculture method utilizing a novel apparatus, the bioplorer, was developed. The bioplorer is composed of an efficient cell separation unit, a focusing-free microscopic device, and an image analysis program. A meat or vegetable suspension is poured into the cell separation funnel, and insoluble matter in the sample suspension is trapped by prefilters. Microbial cells passing through the two prefilters are then trapped by the membrane filter (pore size, 0.4 microm). Trapped cells are double-stained with 4',6'-diamidino-2-phenylindole and propidium iodide, and the membrane filter is removed and set on the focusing-free microscope. A fluorescent image is then recorded. Total numbers of viable and dead cells on the membrane filter can thus be determined automatically. One assay can be performed within 10 min, which is much faster than the culture method. The results obtained with both the nonculture method and the culture method for meat and vegetable samples were highly correlated (r = 0.953 to 0.998). This method is feasible for the practical purpose of food safety control.

Bacteria↗
PubMed1991

[Optimizing cell separation with the Cell Separator AS-106].

Seventeen different separation protocols based on more than 1100 thrombocytaphereses were tested. Twelve of these are reported on in this study. It became apparent that the most important variable is the centrifugation speed (1900 rpm at a blood flow of 50 ml/min). This made it possible to collect 3.5 to 3.8 x 10(11) thrombocytes (approx. 60% extraction efficiency) from 3.15 l blood. Further optimization of this procedure is desirable, since 10% of the thrombocytes still remain in the separation chamber. However, our optimization work was successful as far as the reduction of leukocyte and erythrocyte contamination is concerned, which ultimately resulted in leukocyte and erythrocyte contamination of about 1 x 10(7).

Blood Component Transfusion↗
PubMed1989

Heterogeneous lymphokine-activated killer cell precursor populations. Development of a monoclonal antibody that separates two populations of precursors with distinct culture requirements and separate target-recognition repertoires.

We developed a monoclonal antibody (mAb) 211, which recognizes the precursors in peripheral blood of lymphokine-activated killer cells (LAK) induced by recombinant interleukin-2 (rIL-2). In conjunction with complement mAb 211 also eliminates natural killer cells (NK) and a majority of the cytotoxic T lymphocytes. B cells and monocytes do not express the 211 antigen. Since mAb 211 recognized such a large percentage of peripheral blood lymphocytes we examined which 211+ subpopulation was the predominant precursor of rIL-2-induced LAK cells using two-color fluoresence-activated cell sorting (fluorescein-conjugated 211 mAb plus phycoerythrin-CD11b). This method identified the 211+/CD11b+ population as the predominant phenotype of the rIL-2-induced LAK precursor. In addition, we directly compared the phenotype of the LAK precursor induced by delectinated T-cell growth factor (TCGF) to that induced by rIL-2. The 211-depleted population, which was devoid of NK cells and LAK precursors (inducible by rIL-2), was capable of generating LAK activity when TCGF was used as the source of lymphokine. LAK cells induced by TCGF from the 211-depleted population lysed a fresh sarcoma and an NK-resistant cultured melanoma tumor target but not the Daudi cell line, which was lysed by rIL-2-induced LAK cells. Lymphoid subpopulations, depleted using NKH1a mAb, behaved similarly, generating high levels of lysis against the two solid tumor targets when cultured with TCGF but not with rIL-2. CD 3-depleted populations showed enrichment for LAK precursors using either rIL-2 or TCGF. These results indicate that while rIL-2-induced LAK precursors cannot be separated from cells with NK activity, TCGF-induced LAK cells can be generated from populations of peripheral blood mononuclear cells without NK activity.

Antibodies, Monoclonal↗
PubMedDate not supplied

[Progress in the therapy of children with congenital hemolytic anemias by transfusion of neocyte concentrations. Initial experiences in the separation and transfusion of young erythrocytes, obtained with the cell separator Fenwal CS-3000].

Transfusion-induced hemochromatosis remains a major therapeutic complication in the management of patients with chronic hemolytic anemias. Red cell units harvested with blood cell separators have an average estimated mean cell age of 30 days, compared to 60 days for unfractionated blood. Our initial experience with transfusion of neocytes indicates that the amount of transfused erythrocytes can be reduced on 60 per cent. Further studies must demonstrate the clinical benefit. When combined with modern iron chelator regimens, it may be possible to achieve consistently negative iron balance prior to the onset of hemochromatosis which would allow patients to probably lead a normal life-span.

Anemia, Hemolytic, Congenital↗
PubMed1988

Separation of mononuclear bone marrow cells using the Cobe 2997 blood cell separator.

In the present study, we report the results of our evaluation of the use of the continuous-flow cell separator Cobe 2997 to isolate from human bone marrow (BM) aspirates the mononuclear cell (MNC) fraction containing hematopoietic stem cells. This MNC concentrate is isolated in 15% of the original BM volume and contains 23% of the initial nucleated cells. It is enriched as concerns the BM MNC fraction (lymphocytes + monocytes recovery; 80%), whereas the contamination with granulocytes, red blood cells and platelets is reduced to 7.2, 1.5% and 41%, respectively, of the cells initially present in the BM suspensions. Furthermore, it is demonstrated that this MNC concentrate is highly enriched in granulocyte-macrophage-colony-forming cells (CFU-GM; recovery 83%). The method is simple, inexpensive, efficient and reproducible. It allows rapid processing of a large volume of BM without substantial loss of hematopoietic progenitor cells. It represents a valuable method of BM MNC concentration prior to further in vitro manipulations such as T cell or tumor cell depletion or cryopreservation.

Adolescent↗
PubMed2006

Improvement of immunomagnetic separation for Escherichia coli O157:H7 detection by the PickPen magnetic particle separation device.

Conventional immunomagnetic separation (IMS) procedures, which use an external magnetic source to capture magnetic particles against the side of a test tube, are labor-intensive and can have poor sensitivity for the target organism because of high background microflora that is not effectively washed away during the IMS process. This report compares the conventional IMS procedure to a new IMS procedure with an intrasolution magnetic particle transfer device, the PickPen. The IMS target for the majority of these studies is Escherichia coli O157:H7 in various types of samples, including cattle feces, hides, carcasses, and ground beef. Comparison of the two IMS methods showed a significant difference (P < 0.05) in the efficiency of detecting E. coli O157:H7 from cattle carcass surface, cattle hide, and cattle fecal samples. No significant improvement (P > 0.05) in E. coli O157:H7 detection was observed when the PickPen IMS procedure was used to isolate this pathogen from ground beef samples. Use of the PickPen IMS greatly increases the throughput of the IMS procedure and may be more compatible with various emerging technologies for pathogen detection. In addition, the efficacy of sequential IMS for multiple pathogens is reported herein.

Animals↗
PubMed1987

Separation and functional analysis of bone marrow cells separated by rhodamine-123 fluorescence.

Mouse bone marrow (BM) cells were separated on the basis of fluorescence intensity after labeling with the supravital, fluorescing dye rhodamine 123 (Rh 123). Rh 123 accumulates in the mitochondria. The BM fractions were tested for the presence of spleen colony-forming units (CFU-S) that produced colonies at day 8 and day 12 after bone marrow transplantation; for the ability to rescue lethally irradiated mice; and for thymus-repopulating ability. The results showed that all the day-8 CFU-S incorporated a relatively large amount of Rh 123, while the day-12 CFU-S were stained heterogeneously. Survival after lethal irradiation, as expressed in the numbers of day-12 CFU-S transplanted, was predominately mediated by the weakly fluorescing fraction. However, early thymus repopulation, which is caused by prothymocytes contained in the graft, was mediated by the brightly fluorescing fraction. Data in the literature indicate that a high uptake of RH123 is correlated with cellular proliferation. This suggests that all the day-8 CFU-S and about 60% of the day-12 CFU-S are cycling. In contrast, less than 10% of both day-8 and day-12 CFU-S are killed by S-phase-specific agents. From this we conclude that a high uptake of Rh 123 depends on other factors in addition to the cell cycle status. It is suggested that differentiation processes in which the day-8 CFU-S appears to be involved also cause the presence of many or very active mitochondria. The difference between the weakly and brightly fluorescing fractions in the number of day-12 CFU-S required for 30-day survival after lethal irradiation, suggests that there is heterogeneity among the day-12 CFU-S population or that the fraction weakly labeled with Rh123 contains other, less mature, cells that are responsible for survival after lethal irradiation. Finally, the presence of prothymocytes in the brightly labeled fraction shows that these cells are different from the stem cells that protect lethally irradiated mice.

Animals↗
PubMed1977

[Efficiency of the blood cell separator Haemonetic 30 in the separation of platelets from single donors].

By means of the Haemonetic 30 separator we were able to collect 4.1 +/- 0.94 X 10(11) (X +/- 1 SD) platelets in 57 procedures consisting of 5-6 cycles. The platelet yield was significantly influenced by the blood volume processed and by initial platelet counts in donors. Augmenting platelet collection volume in the red colored part of the buffy-coat from 10-20 ml did not increase the yield. Transfusion of collected platelets into 27 non-sensitized patients showed normal recovery of 43% at one hour and shortening of bleeding time from over 30 min to a mean of 5 min 20 sec in 12 patients tested. Autotransfusion of 51Cr-labeled platelets into 8 healthy donors revealed identical recoveries (42 +/- 12%) and a normal survival time (9.2 +/- 0.7 days).

Cell Separation↗
PubMed2005

Chiral separation in capillary electrophoresis using dual neutral cyclodextrins: theoretical models of electrophoretic mobility difference and separation selectivity.

Simple equations and theoretical models, related to enantioselectivity (kappa) and C, have been developed for prediction of electrophoretic mobility difference (Deltamu) and separation selectivity (alpha) for enantiomers in CE using dual CDs, where alpha and kappa are defined as the ratio of mu and the ratio of binding constant (K) for enantiomers to each CD, respectively, C the CD concentration, and the average K for enantiomers and each CD. Experiments were carried out using dual CDs as beta-CD and dimethyl-beta-cyclodextrin (DM-beta-CD) and test analytes as five pairs of amphetamine drug enantiomers. A change in observed Deltamu and alpha of enantiomers in dual CDs was found to be in excellent agreement with the theoretical models. For example, in comparison with single CD1, dual CDs can enhance Deltamu and alpha up to the maximum value when enantiomers migrate with the same order in CD1 and CD2, and have the value of rho > 1.0, where rho is the enantioselectivity ratio for CD2 to CD1, while worse Deltamu and alpha are obtained for enantiomers with rho < 1.0.

Amphetamines↗
PubMed1979

Properties and separation of T lymphocyte growth stimulatory activity (TL-GSA) and of granulocyte-macrophage colony stimulatory activity (GM-CSA) produced separately from two human T lymphocyte subpopulations.

We have previously identified two stimulatory activities affecting blood cell maturation in PHA-stimulated human lymphocytes conditioned medium (PHA-LyCM). One was granulocyte-macrophage colony stimulatory activity (GM-CSA), and the other was T lymphocyte growth stimulatory activity (TL-GSA) in suspension culture. In this paper we have shown that although both activities can be produced from purified non-adherent human T lymphocytes, they are produced from two distinct subpopulations. The production of these activities was greatly enhanced by T cell mitogens. Both protein factors were relatively heat stable (56 degrees, 30 minutes), were sensitive to trypsin treatment and were specific for primate blood cells. These two activities were fractionated by means of ammonium sulfate precipitation, Sephadex G-150 gel filtration, DEAE cellulose and Con A-Sepharose column chromatographies. MW of the major peak estimated from the elution volume of gel filtration in the presence of 0.5 M NaCl was 40,000 for GM-CSA and 13,000 for TL-GSA. Results from Con A-Sepharose column showed that while about 70% of TL-GSA was bound to Con A, less than 25% of GM-CSA was bound. These observations show that the majority of TL-GSA and GM-CSA were separable by these two conventional column chromatographic methods.

Ammonium Sulfate↗
PubMed1979

Dual-isotope separation technique for radioassay. Precision of calculated results affected by degree of separation.

The dual-isotope separation technique for radioassay is reviewed. An expression is derived describing the effect of counting errors on the precision of the calculated bound count rate in the dual-isotope technique. This mathematic model is tested in experiments using sodium iothalamate (I-125) as a marker in the Phadebas radiosorbent assay of cobalamin (Co-57). The coefficient of variation of results calculated on the basis of the dual-isotope technique is shown to be dependent on the amount of supernatant removed. The conclusion is that relatively large amounts of the supernatant must be removed before counting if the dual-isotope technique is to give acceptable results. The experimental model is proposed as a simple test of the suitability of a projected dual-isotope system.

Analysis of Variance↗
PubMed1995

Capillary zone electrophoretic resolution of recombinant human bone morphogenetic protein 2 glycoforms. An investigation into the separation mechanisms for an exquisite separation.

Recombinant human bone morphogenetic protein 2 (rhBMP-2) is a disulfide-linked homodimeric glycoprotein (M(r) = 30,000) which induces bone formation in vivo in several animal model systems. In this paper, we report the separation of a homogeneous rhBMP-2 sample into nine peaks by capillary zone electrophoresis (CZE), using a simple, pH 2.5, phosphate buffer containing no additives. The nine peaks have been identified to be glycoforms of rhBMP-2 [designated as (rhBMP-2)2-(GlcNAc)4(ManZ), where Z varies from 10 to 18]. The difference between any adjacent pair of peaks is only one mannose residue (M(r) = 162). The ability of CZE to resolve rhBMP-2 glycoforms having the same charge and differing only 0.5% in molecular mass, without resorting to chemical complexation, is both unexpected and intriguing. Possible mechanisms explaining how the additional mannose can affect the mobility of rhBMP-2 glycoforms were explored. Zeta potentials of various glycoforms were calculated from their mobilities and interpreted in light of diffuse double layer parameters. Our results suggest that CZE employing a low-pH buffer, where proteins are highly charged, may be uniquely suitable for complex protein glycoform analysis.

Amino Acid Sequence↗
PubMed1981

Phase separation, charge separation and biogenesis.

The current view of bioenergetics postulates transmembrane charge separation as a primary mechanism of energy storage and transformation. Using that bioenergetic view we examine possible methods of photon driven transduction in primordial vesicles. Two possible types of proton pumps are analyzed and a method of anaerobic photophosphorylation is discussed. Using these principles we theorize about the formation of prebiotic photochemical vesicles utilizing the same transmembrane energy conversions characteristic of contemporary cellular systems.

Anaerobiosis↗
PubMed2001

Unusual effects of separation conditions on chiral separations.

Unusual effects in liquid chromatographic separations of enantiomers on chiral stationary phases are reviewed with emphasis on polysaccharide phases. On protein phases and Pirkle phases reversal of the elution order between enantiomers due to variation of temperature and mobile phase composition has been reported. Most of the nonanticipated observations have dealt with the widely used polysaccharide phases. Reversed retention order and other stereoselective effects have been observed by variation of temperature, organic modifier and water content in nonpolar organic mobile phases.

Chromatography, Liquid↗
PubMed1987

Evaluation of advanced silica packings for the separation of biopolymers by high-performance liquid chromatography. V. Performance of non-porous monodisperse 1.5-microns bonded silicas in the separation of proteins by hydrophobic-interaction chromatography.

Non-porous monodisperse 1.5-microns silicas were allowed to react with (A) and (B) N-acetylaminopropyltriethoxysilane to generate bonded phases useful in high-performance hydrophobic-interaction chromatography (HIC). Differences in the selectivity were observed between the amide and the ether phase. Peak capacities between 10 and 30 were achieved for several proteins with the amide and ether phase packed into columns of 36 X 8 mm I.D. and elution of the proteins under chromatographic conditions in which the gradient volume, VG, was held constant by varying the gradient time between 20 and 2.5 min and the flow-rate between 0.5 and 4.0 ml/min. The S values derived from the dependences of log k' on the volume fraction of the low ionic strength buffer, phi b, were of the same magnitude as reported for porous HIC silicas and showed a dependence on the molecular weight of the protein. Using these HIC stationary phases based on non-porous 1.5-microns supports, fast separations (less than 5 min) could be carried out with high biological recoveries.

Ammonium Sulfate↗