SEARCH · PubMed Health

Results for “Polystyrenes”

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 523 records · Page 29Linked to original sources

PubMed1984

The adsorption behaviour of two commercial IgG-preparations onto a polystyrene latex surface.

The adsorption behaviour of two commercial preparations of human IgG onto a polystyrene latex surface was studied. The adsorption isotherms obtained differed markedly; one preparation showed a plateau value of 0.4 microgram cm-2 which was reached at 0.1 g l-1, whereas the other preparation showed no plateau value within the concentration range studied (0.1-7.0 g l-1). Characterization by means of iso-electric focusing and HPLC also showed differences between the two preparations. No differences were observed when immuno-electrophoresis was carried out. These results stress the necessity for proper characterization of proteins used in adsorption studies.

Adsorption↗

PubMed1984

Interactions of human platelets with insoluble anticoagulant modified polystyrene resins.

The interactions of two insoluble anticoagulant polystyrene derivatives with human platelets were studied in an in vitro system similar to a chromatography column. Blood was pumped through the column and platelets were counted before and after passage through the column. Interaction of platelets with the beads led to retention of platelets in the column. The same experiment was performed with several donors. Different pretreatments were assayed and compared for both materials: platelet poor plasma, antithrombin III-depleted platelet poor plasma and an antithrombin III solution. Platelet retention depends on the polymer composition: the material containing glutamic acid sulphamide groups, which has a larger anticoagulant activity in plasma than the materials only substituted by sulphonate groups, is always less reactive towards platelets. The differences in the effects of pretreatment on both materials can be correlated with the variations of antithrombin adsorption on the synthetic surfaces.

Anticoagulants↗

PubMed1987

Heparin-like activity of insoluble sulphonated polystyrene resins. Part III: Binding of dicarboxylic amino acids.

It has been demonstrated previously that polystyrene sulphonate possesses anticoagulant properties and that the binding of some amino acids could enhance the heparin-like properties of such resins. These properties depend on the surface density of the active groups, the nature and binding of the group and on the net change borne by the polymer. In this paper, we describe the preparation of copolystyrene (sulphonate-dicarboxylic amino acid sulphamide) resins. By measuring their antithrombotic-surface-activity, we demonstrate that the activity developed by each carboxyl group is at least roughly the same as the activity of one sulphonate group, except in the case of aspartic acid sulphamide resin for which a cooperative effect is shown. The anticoagulant properties of resins bearing phosphonate or monocarboxylic amino acid sulphamides are also examined.

Amino Acids, Dicarboxylic↗

PubMed1988

Adsorption of plasma proteins onto anticoagulant polystyrene derivatives: a fluorescence study.

Quenching of fluorescence was used to monitor adsorption of thrombin (T), antithrombin (AT) and their inactive complex (T-AT) onto three anticoagulant biomaterials made of polystyrene beads bearing the functional groups of heparin. An adsorption capacity of 0.12 mumol of T per mg of polymer allowed the formation of a monolayer of protein at the polymer surface. An affinity constant of 3 x 10(7) l.mol-1 between thrombin and polymer was estimated, whatever the polymer used. The affinity of T-AT was similar although weaker. Desorption of proteins from the polymeric interface by means of polycations (polybrene and polylysine) showed that the inactive complex T-AT is more quantitatively and easily released than thrombin.

Adsorption↗

PubMed1988

Adsorption of thrombin from buffer and modified plasma to polystyrene resins containing sulphonate and sulphamide arginyl methyl ester groups.

The adsorption of albumin and thrombin to insoluble modified polystyrene resins bearing sulphonate (PSSO3) and L-arginyl methyl ester groups (PAOM) was investigated in both purified and plasma systems. Radioiodinated proteins were used to follow adsorption in a 'minicolumn' experiment. Albumin adsorption was found to follow the Langmuir model and specific surface areas of the various resins were evaluated from plateau albumin adsorption data. The adsorption isotherms of thrombin both in buffer and in antithrombin III/fibrinogen-free plasma were also found to be Langmuir-like, and the quantities adsorbed at the isotherm plateaux are in the monolayer range. Analysis of the isotherms at 4 degrees and 37 degrees C for the purified system shows that adsorption is endothermic. Adsorption capacities in plasma remain high (30-50% of those in the purified system) despite competition from the other plasma proteins. These data confirm the strong affinity and selectivity of these resins for thrombin.

Adsorption↗

PubMed1988

Adsorption of enzymes at the solid-liquid interface. I. Trypsin on polystyrene latex.

The enzyme, trypsin, has been used to study conformational changes which occur when protein adsorption onto well-characterized, emulsifier-free, polystyrene latex surface takes place. The adsorption isotherm is of the high affinity, Langmuirian type with plateau adsorption of trypsin of 2.8 mg m-2. The enzymic activity of adsorbed trypsin to low molecular weight substrate is found to decrease as the surface coverage decreases indicating that 'spreading' or unfolding of the native protein conformation, with consequent loss of enzymic activity, occurs. On the close packed surface such 'spreading' is inhibited by steric factors. The view that protein adsorption onto hydrophobic surfaces is dominated by the entropy gain due to protein unfolding to maximize hydrophobic interactions is thus supported.

Adsorption↗

PubMed1988

Adsorption of fibrinogen on to polystyrene latex coated with the non-ionic surfactant, poloxamer 338.

We have measured the isothermal adsorption of 125I-fibrinogen on to polystyrene latex (PSL), which was prepared without surfactants, and on to PSL with an adsorbed coat of poloxamer 338 (an A-B-A block copolymer where A is poly(oxyethylene) and B is poly(oxypropylene]. The plateau adsorption of fibrinogen, at 310 K, was significantly lower on to latex coated with poloxamer 338. Previous studies have shown that poloxamer 338-coated PSL is cleared less avidly than uncoated PSL by cells of the mononuclear phagocytic system (MPS). Our findings are quantitative evidence in support of the theory that the uptake of colloids by the MPS can be related to the interfacial adsorption of opsonic proteins.

Adsorption↗

PubMed1989

Change in cytoplasmic free Ca2+ concentration in rabbit platelets contacting with albumin coated and uncoated polystyrene surfaces.

Direct measurement of cytoplasmic free Ca2+ concentration in rabbit platelets in contact with polystyrene latexes was examined by monitoring an intracellular trapped fluorescent indicator dye, Fura 2, as a quantitative evaluation of platelet activation on material surfaces. It was found that an increase in cytoplasmic free calcium levels in platelets in contacting latexes was strongly reduced by the adsorption of albumin on the latex surfaces. Further, such an elevation of cytoplasmic free calcium levels was found to require a calcium influx from an extracellular medium across the platelet-plasma membrane.

Animals↗

PubMed1992

Insoluble DNA-like phosphorylated polystyrene: specific interactions with anti-DNA antibodies from systemic lupus erythematosus patients.

Systemic lupus erythematosus (SLE) is an autoimmune disease. Antibodies directed mainly against DNA and/or phospholipids are present in the serum of SLE patients. Therefore phosphorylated polystyrene derivatives acting as DNA-like polymers should be able to interact with the SLE anti-DNA antibodies. Such functional polymers were synthesized and subsequently their interactions with the anti-DNA antibodies studied. Adsorption experiments performed with both anti-DNA antibodies and normal immunoglobulins showed high affinity constants of the phosphorylated polymer for anti-DNA antibodies (4 x 10(9) M-1) whereas for normal IgG the affinity was low (2 x 10(5) M-1). Moreover, the interaction was specific involving the idiotypic moiety of the anti-DNA antibodies and an array of phosphoester groups at the surface of this biomaterial.

Adsorption↗

PubMed1995

Adsorption of fibronectin and vitronectin onto Primaria and tissue culture polystyrene and relationship to the mechanism of initial attachment of human vein endothelial cells and BHK-21 fibroblasts.

The two cell culture substrata, tissue culture polystyrene (TCPS) and Primaria, were compared in order to determine whether a nitrogen-containing surface such as Primaria attracts cells by a different mechanism to an oxygen-containing surface (TCPS). The amounts of vitronectin (Vn) and fibronectin (Fn) which adsorb from the fetal bovine serum (FBS) component of the culture medium onto Primaria and TCPS were determined. Primaria adsorbed two- to threefold more Fn than TCPS, but adsorbed similar amounts of Vn from medium containing FBS. The Fn and Vn binding sites on Primaria were distinct, as adsorption was non-competitive between these two proteins. The amounts of Fn and Vn that adsorbed onto the two surfaces were compared to the concentration dependence of the cell attachment activities of Fn and Vn. Whereas the amounts of Fn which adsorbed onto TCPS were suboptimal for cell attachment, Primaria adsorbed an Fn surface density that was supraoptimal for attachment of human vein endothelial cells and BHK-21 fibroblasts. We conclude that Primaria differs from TCPS in that both Fn and Vn mediate initial cell attachment to Primaria when the culture medium contains FBS, whereas cell attachment to TCPS is dependent upon Vn.

Adsorption↗

PubMed1996

Adhesion and proliferation of cultured human aortic smooth muscle cells on polystyrene implanted with N+, F+ and Ar+ ions: correlation with polymer surface polarity and carbonization.

Physicochemical surface properties and biocompatibility were studied in polystyrene (PS) implanted with 150 keV N+, F+ and Ar+ at doses ranging from 1 x 10(12) to 1 x 10(15) cm-2. Adhesion and proliferation of cultured human aortic smooth muscle cells (SMCs) on ion implanted PS were thoroughly examined for dependence on implanted dose and ion species and in close relation to polymer surface oxidation, surface polarity, concentration of conjugated double bonds and sheet resistivity. The surface polarity of PS was a smooth, increasing function of the implanted dose. However, the dependence of SMC population density on the implanted dose was found to be more complicated. After 18 h cultivation time (i.e. when only cell attachment and spreading took place), the number of adhered SMCs and their degree of spreading first increased with increasing ion dose, and after reaching a maximum at the dose of 5 x 10(12) cm-2, they decreased to original values. For doses above 5 x 10(14) cm-2, an increase in SMC population density and spreading was again observed. The first maximum in cell adhesion can be explained by slight increases in the surface polarity and wettability, optimal for cell adhesion, and the second maximum by progressive carbonization of the PS surface. After 96 h cultivation time (i.e. when the cells proliferated intensively), the dramatic dependence of the SMC population density on implanted dose is mostly smeared out. This observed dependence of SMC attachment, spreading and subsequent proliferation on the implanted dose was similar in all three ion species, but highest cell densities were achieved on PS implanted with F+ ions.

Argon↗

PubMed1984

The antigenicity of myoglobin-related peptides synthesised on polyacrylamide and polystyrene resin supports.

Polyacrylamide resins [Atherton et al., Bioorg. Chem. 8, 351-370 (1979)] have been found suitable for solid-phase radioimmunoassay of peptides synthesised on the same supports; they are sufficiently stable during side-chain deprotection and swell sufficiently in aq. media to admit antibody molecules to the sites of peptide attachment. A re-examination of five synthetic peptide sequences corresponding to (15-21), (56-62), (94-99), (113-119) and (145-151) of beef myoglobin analogous to those delineated by Atassi [Immunochemistry 12, 423-438 (1975)] for sperm whale myoglobin shows that they all bind anti-beef myoglobin antibodies raised in rabbits, with binding capacities in the order V = III greater than IV greater than I = II. The resin-bound peptide (72-88) binds such antibodies even more extensively, as do certain sequential variants of peptide V. Other peptides, bound to polyacrylamide or polystyrene resins but unrelated to any of the five sequences and varying in size and amino acid composition and sequence were also tested with various antisera. It was concluded that the antibody binding properties of the 30 or so small peptides (two-seven residues) are dominated by their cationic and/or hydrophobic properties. In small peptides, therefore, antibody binding can be safely interpreted only in terms of general structural properties but not in terms of biological specificity. The latter property becomes assessable only with peptides representing larger areas of antigenic protein surfaces.

Acrylic Resins↗

PubMedDate not supplied

Growth of fermentative and non-fermentative yeasts in natural yoghurt, stored in polystyrene cartons.

Permeation of oxygen through polystyrene packaging is a factor in the growth of yeasts in natural yoghurt. Diffusion of oxygen through the packaging material can permit the growth of non-fermentative yeasts in yoghurt stored at refrigeration temperatures. Yarrowia lipolytica, a non-fermentative yeasts which does not utilize lactose was isolated from yoghurt. The growth in natural yoghurt of Yarrowia lipolytica and the lactose-fermenting yeast Kluyveromyces marxianus was investigated. Both yeasts grew in yoghurt with reduced fat content. Storage of yoghurt in an anaerobic atmosphere eliminated growth of Yarrowia lipolytica but permitted fermentative growth of Kluyveromyces marxianus.

Fermentation↗

PubMed1989

Effect of antibiotics on CR1 receptor levels of human neutrophils and on the binding and phagocytosis of opsonized polystyrene microspheres by these leucocytes.

Fourteen antibiotics were studied for their effects on the following properties or functions of normal, human neutrophils: (1) the expression of CR1 receptors; (2) the total binding of C3b.IgG-coated polystyrene microspheres in the presence of cytochalasin D to inhibit phagocytosis; (3) the net phagocytosis of the opsonized microspheres; (4) the residual, external binding after phagocytosis. Fluorescence, flow cytometric methods were used to determine binding and phagocytosis of the model target particles. Only nafcillin, a penicillin, caused a decrease (33 per cent) in phagocytic capacity of the neutrophils at a physiologically significant dose (serum level); the antifungal antibiotic, amphotericin B, caused a 30 per cent increase in phagocytic capacity. These small changes in neutrophil phagocytic capacity may not be physiologically significant. There were no significant differences in the four measured parameters caused by other antibiotics tested at physiologically significant doses.

Amphotericin B↗

PubMed1991

The effect of size of polystyrene particles on their retention within the rat peritoneal compartment, and on their interaction with rat peritoneal macrophages in vitro.

Polystyrene particles (size range 300 nm-3 microns diameter) were radioiodinated and their capture by rat peritoneal macrophages measured in vitro. For unmodified particles, most efficient accumulation was observed using a diameter of 600 nm (Endocytic Index (E.I.) = 16.4 +/- 2.9 microliters/10(6) cells/h). Particles (3 microns diameter) which had been modified to become more hydrophilic by hydroxymethylation showed an increased rate of capture (E.I. = 136.6 +/- 91.2 microliters/10(6) cells/h). Following intraperitoneal administration to rats, unmodified 3 micron particles showed selective accumulation in the omentum (18.4% injected dose/g), and this was increased for the hydroxymethylated bead (35.3% dose/g). The smaller (800 nm) particles were better able to leave the peritoneal compartment. Radiolabelled particles isolated from a peritoneal wash after 5 h were mostly cell-associated (72-86%, depending on the type of particle).

Animals↗

PubMed1989

A collaborative study of the analysis of doxycycline hyclate by high-performance liquid chromatography on polystyrene-divinylbenzene packing materials.

An improved method for the analysis of doxycycline hyclate by high-performance liquid chromatography using polystyrene-divinylbenzene column packings is described. The separation obtained with this method was compared with that of other, recently described methods. The improved method was examined in a collaborative study involving five separate laboratories, using 11 different columns and four discrete samples. The main component and impurities were determined. An analysis of variance showed absence of consistent laboratory bias and presence of significant laboratory-sample interaction. Estimates for the repeatability and reproducibility of the method, expressed as relative standard deviations (RSD) of the result of the determination of doxycycline, were found to be 0.9 and 1.2%, respectively.

Chromatography, High Pressure Liquid↗

PubMedDate not supplied

Collaborative study of the analysis of chlortetracycline hydrochloride by liquid chromatography on polystyrene-divinylbenzene packing materials.

A previously established method for the analysis of chlortetracycline by liquid chromatography using polystyrene-divinylbenzene stationary phases was examined in a multicentre study involving four laboratories and a total of 12 columns. Three chlortetracycline hydrochloride samples were analysed. The main component and the impurities were determined. An analysis of variance, treating each column as a different laboratory, showed absence of consistent laboratory bias and presence of significant laboratory-sample interaction. Estimates for the repeatability and reproducibility of the method, expressed as relative standard deviations of the result of the determination of chlortetracycline hydrochloride, were calculated to be 0.7 and 1.2%, respectively. When the analysis of variance was performed using only the results obtained on the wide pore (1000 A) stationary phases, the laboratory-sample interaction strongly decreased. It is therefore proposed to use such materials for the analysis of chlortetracycline.

Analysis of Variance↗

PubMed2004

On-chip micro-flow polystyrene bead-based immunoassay for quantitative detection of tacrolimus (FK506).

Tacrolimus (FK506) is a widely used immunosuppressant for preventing allograft rejection and the treatment of atopic dermatitis. FK506 necessitates therapeutic drug monitoring because of inter- and intrapatient variability and the lack of correlation between the administered dose and the blood concentration. Previous immunoassay-based methods required a relatively long assay time and troublesome liquid-handling procedures. In the present study, we aimed to establish a rapid monitoring method for FK506 determination by using a poly(dimethylsiloxane) (PDMS)-based microfluidic device. Polystyrene beads were coated with mouse anti-FK506 antibody and placed in the flow channel. As a competitive assay, sample solution was allowed to react in the flow channel. After the addition of the fluorogenic substrate, the fluorescent signal was observed under a microscope. As a result, the developed assay allowed a short detection time of approximately 15 min per each sample and a high sensitivity even by using only a single bead. The feasibility of performing a competitive assay using a PDMS-based antibody chip gives promising results over the existing immunoassay-based methods.

Animals↗