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PubMed1989

Non-specific cell binding characteristics of para-magnetic polystyrene microspheres used for antibody-mediated cell selection.

The binding of cells to paramagnetic polystyrene microbeads in the absence of coupling antibodies was measured. Cells from normal bone marrow, from an acute lymphoblastic leukemia (ALL) cell line or from a neuroblastoma cell line, were labeled with the fluorochrome Hoechst 33342 and incubated with microbeads by rotation at 4 degrees C. Following this incubation, the microbeads with all attached cells were collected using an externally applied magnetic field and visualized by microscopic examination under ultraviolet illumination. The incubation variables included the protein content of the medium, and the period of rotation. Normal bone marrow was found to adhere sparingly to the microbeads; less than 1.0% of the total nucleated cell population was recovered with the beads, whereas greater than 5% of the ALL cells and greater than 30% of the neuroblastoma cells were found to bind non-specifically to the microspheres. Neither changes in the protein concentration of the medium or in the incubation period significantly altered the non-specific binding of the cell types examined. It is thus apparent that the use of these microspheres for positive selection of cells, such as the collection of hematopoietic stem cells for transplantation, would be compromised by a sizeable non-specific interaction. Modification of the surface of the microspheres to substantially reduce this interaction will be necessary before efforts at positive selection using the magnetic microspheres can be fruitful.

Antibodies↗

PubMed1990

Haptenated nylon-coated polystyrene plates as a solid phase for ELISA.

An ELISA system, based on the novel use of a hapten-nylon conjugate as solid-phase coating antigen, has been applied in the screening of hybridoma cultures for anti-hapten monoclonal antibodies directed against the herbicide atrazine and its derivatives. Conjugation of a 2-aminocaproic acid derivative of atrazine with DCC to polyamide (Nylon 6) gave haptenated nylon which was soluble in aqueous cresol-ethanol mixtures and adsorbed efficiently on polystyrene microtitre plates. Reproducible ELISA results were obtained with culture supernatants of hybridomas derived from spleen cells of mice that had been immunized with atrazine-bovine serum albumin conjugates. Satisfactory results were also obtained with a water soluble peptide conjugated to nylon for use as a coating antigen in an ELISA. Plates coated with hapten-nylon as antigen have the added advantage that they can be stored at room temperature for at least 6 months without loss of activity. Nylon therefore appears to have general applicability as a carrier for both non-polar and polar haptens in the preparation and use of coating antigens.

Adsorption↗

PubMed1991

Human serum induced opsonization of immunoglobulin G-coated polystyrene microspheres with complement components C3 and C4 as measured by flow cytometry.

Human IgG-coated polystyrene microspheres (IgG-ms) were incubated with human serum followed by biotinylated monoclonal anti-C3d or anti-C4d antibody, and phycoerythrin-streptavidin. The intensity of fluorescence was measured by flow cytometry and corresponds to the amount of deposited C3 and C4. Binding of C3 and C4 was dependent on the activation of the classical pathway of complement and on the amount of IgG adsorbed to the particles. No deposition was observed on control particles coated with bovine serum albumin or ovalbumin. Incubation of constant amounts of IgG-ms with increasing amounts of normal human serum (NHS) resulted in a dose-dependent increase in C3 deposition. The same result was found for C4 deposition at moderate NHS dilutions, but less C4 was detectable using a higher input of NHS. Half-maximum C3 and C4 deposition was observed at a mean serum dilution of 1/114 and 1/520, respectively (n = 26). No correlation was found between C4 or C3 deposition and either total C4 and C3 serum concentrations as measured by nephelometry or complement-mediated lysis of antibody-coated sheep red blood cells. Reduced or absent C4 or C3 deposition was found in the sera of patients with low amounts or deficiencies of components involved early in classical complement pathway activation whereas essentially normal C4 or C3 deposition was obtained with the sera of patients with deficiencies in components of the membrane attack complex. With this simple and specific functional assay using stable reagents an altered function of early components of the classical pathway of complement may be quickly and reliably detected in routine diagnostic laboratories. Moreover, such opsonized and well characterized particles may be useful in assays of phagocytic cell function.

Complement C3↗

PubMed1992

Characterization of monoclonal antibodies physically adsorbed onto polystyrene latex particles.

The physicochemical and immunochemical properties of monoclonal antibodies (MAbs), adsorbed onto polystyrene latex particles, have been investigated. Both native and pH 2 pretreated MAbs were compared before and after immobilization. It was found that the antigen binding capacity of the immobilized, acidic pretreated MAbs was significantly higher than for the immobilized, native IgG molecules. This enhanced antigen binding capacity appeared to be due to an improved molecular orientation following adsorption of the monomeric, pH 2 treated IgG fraction. Additionally, experiments using F(ab')2 fragments demonstrated that the Fc portion of the MAb molecule is of major importance for achieving the enhanced binding capacity. Binding studies showed that the (apparent) affinity of native and pH 2 pretreated MAbs were similar; the K(a) values of the immobilized MAbs were higher than those of MAbs in solution.

Adsorption↗

PubMed1993

Covalent linking of haptens, proteins and nucleic acids to a modified polystyrene support.

Biological molecules of various molecular weights were successfully linked to polystyrene microtitration plates bearing carbonyl and hydroxyl reactive groups. Cross-linking of proteins, nucleic acids and haptens was carried out with water soluble carbodiimide. The covalent nature of the binding reaction was demonstrated by the immunodetection of a hapten linked to the surface through a disulphide spacer arm and its subsequent release by cleavage of the bridge. The amount of protein fixed per surface unit could be correlated to molecular weight. Nanograms of biotinylated nucleic acids and synthetic polynucleotides could also be retained on the solid support.

Enzyme-Linked Immunosorbent Assay↗

PubMed1995

Grafting peptides onto polystyrene microplates for ELISA.

Three peptides corresponding respectively to two Epstein-Barr viral epitopes and to the c-erbB-2 oncogene product were synthesized with the aim of developing an immunoenzymatic assay. Preliminary experiments indicated that the efficiency of the assay was profoundly affected by the nature of the solid phase for each peptide. In order to optimize the assay the three peptides were covalently coupled to functionalized polystyrene microplates which were used to immobilize both haptens and nucleic acids in a previous study. The results obtained indicate that the use of the carboxylated surfaces permits the linking strategy to be adapted to each peptide. Moreover, high sensitivities (5 x 10(-10)-1 x 10(-13) M) were obtained using amounts of the peptides much lower than those used in the standard system.

Amino Acid Sequence↗

PubMed1983

Protective effect of polystyrene liners for composite resin restorations.

The main purpose of lining cavities before insertion of composite resin restorations is to prevent bacterial contamination at the cavity walls. A thin film of polystyrene liner dissolved in ethyl acetate applied to all surfaces by compressed air provided good protection against bacteria on cavity walls under composite resin restorations. An antibacterial primer in an alcohol solution applied prior to the liner may improve this protection. This procedure had no detectable injurious effect on the pulp.

Animals↗

PubMedDate not supplied

Control of Bancroftian filariasis by integrating therapy with vector control using polystyrene beads in wet pit latrines.

In the town of Makunduchi, Zanzibar, wet pit latrines provided breeding places for Culex quinquefasciatus and there were few other mosquito breeding places available. The adult mosquito population in bedrooms was monitored for a year and found to consist almost entirely of Cx quinquefasciatus of which 2.45% carried infective larvae of Wuchereria bancrofti. It was estimated that each person received about 24,993 bites per year, of which 612 were potentially infective. After a year of baseline data collection, polystyrene beads were expanded in boiling water and applied to form floating layers on all infested pits. Subsequently the adult mosquito population declined remarkably so that the estimated number of bites per person per year was only about 439. To retain control, surveillance for newly wet pits continued to be necessary. Initially the microfilarial rate in the human population was 49.5%, with many cases of filarial disease. The microfilarial rate was reduced to 10.3% by mass treatment with diethylcarbamazine, with no sign of resurgence a year after treatment. The infective rate among mosquitoes was reduced to 0.41% and the combined effect of the vector and microfilarial control was to reduce the number of infective bites per person per year by 99.7%.

Adolescent↗

PubMedDate not supplied

Approaches to vector control: new and trusted. 4. Appropriate technology for vector control: impregnated bed nets, polystyrene beads and fly traps.

There are social, economic and entomological problems with conventional insecticidal spraying methods for vector control. There is therefore interest in alternative technologies, especially the impregnation of bed nets with pyrethroid insecticides against malaria vectors. This method is cheap, socially acceptable and effective where bed nets are already widely used and where malaria transmission is not very intense. In holoendemic areas, and where people consider bed nets unaffordable, there are still unanswered questions. Whether pyrethroid resistance will be selected in anophelines also deserves more attention than it has so far attracted. Where Culex mosquitoes breed in confined sites such as pit latrines, the application of floating layers of polystyrene beads is a long-lasting and effective control method. There is increasing evidence that house flies are important agents in the mechanical transmission of diarrhoea due to Shigella. Simple fly traps can be an effective way of controlling house fly populations and this deserves comprehensive testing in tropical countries.

Animals↗

PubMedDate not supplied

A small scale field trial with expanded polystyrene beads for mosquito control in septic tanks.

A field trial of the use of expanded polystyrene beads (EPSB) to control the breeding of mosquito larvae in household septic tanks was conducted in Sarawak. One week after treatment, the breeding of Culex quinquefasciatus and Aedes albopictus was reduced by 100% and 68.7% respectively. For both species combined, a 57.25% reduction in the adult emergence rate was achieved. No adult was caught in the emergence trap one month after treatment. A reduction in mosquito biting rates was reported by 87.3% of respondents. All households regarded the EPSB treatment as effective. This study has reduced the relatively high infestation rate of A. albopictus in the septic tanks to 16-20%. The EPSB treatment is feasible and practical. Post-treatment assessment using adult emergence traps and the implications for the vector control programme of the local authority are discussed.

Aedes↗

PubMed1982

Interactions of anticoagulant insoluble modified polystyrene resins with plasmatic proteins.

In previous papers, we have described the preparation and heparin-like properties of insoluble modified polystyrene resins. We now report results about the interactions of several coagulation factors with some of these materials. Most of the non-activated factors are neither adsorbed nor modified, except factor V and prekallikrein. In contrast thrombin, antithrombin III and factor Xa adsorb on the surface of such insoluble polymers. Thrombin can be desorbed by addition of a polycationic compound. The inactivation of thrombin or factor Xa by antithrombin is catalysed by the presence in the mixture of these insoluble materials as it is with soluble heparin. The initial velocity of these reactions is second order for both types of catalysis-homogeneous or heterogeneous - as previously reported for soluble heparin. In the case of these insoluble materials, the inhibition of protease by antiprotease seems to be accelerated when complexes are formed between the polymer and the proteins.

Adsorption↗

PubMed1984

Antithrombic properties of insoluble modified polystyrene: Part I.

Chlorosulfonated polystyrenes grafted with arginyl methyl ester have been synthetized and characterized by elemental analyses. When suspended in plasma or in fibrinogen solutions, these insoluble polymers cause an increase in the thrombin clotting time. Consequently the antithrombin activity observed is not dependent upon to the presence of antithrombin III. Binding between the resin and thrombin can be demonstrated. An approximative value of the affinity constant is calculated: 2.3 X 10(6) 1/M. At high ionic strength, thrombin can be desorbed and exhibits normal coagulation properties. The prolongation of the thrombin time therefore can be attributed to the thrombin-resin interaction.

Absorption↗

PubMed1985

Platelet attachment and spreading on polystyrene surfaces: dependence on fibronectin and plasma concentration.

Fibronectin promoted platelet attachment and spreading on polystyrene surfaces but was not essential if the surfaces were coated with plasma. The dependence of platelet adhesion on plasma concentration was complex. The extent of attachment and spreading was increased on surfaces treated with up to 1.0% plasma and decreased at higher plasma concentrations. The results support the hypothesis that protein adsorption is not directly related to protein concentration when surfaces are exposed to complex protein mixtures.

Adsorption↗

PubMed1990

Molecular weight-dependent contact activation of plasma induced by soluble polystyrene and dextran derivatives.

The surface dependent contact activation of human plasma was studied as a function of the molecular weight of several synthetic macromolecular and watersoluble derivatives: polystyrene sulphonates, dextran methyl-benzylamide sulphonate/carboxylates as well as dextran sulphates as reference materials. Extent of the contact activation was determined by the amidolytic activities generated from cold activation of plasma in the presence of dilutions of the polymers for varying incubation times. The activating properties of the materials have been rationalized by means of a parameter calculated from the shapes of the amidolytic rates vs. incubation time variations. It was found that all the studied polymers behave similarly: contact stimulating properties begin to increase sharply passed a molecular weight of 25,000 and thereafter gradually reach a limiting plateau for Mw = 100,000. Activating capacities estimated for these limiting values have been expressed in term of specific capacities unrelated to Mw effects. These parameters were also compared to that of standard heparin estimated in the same conditions.

Blood Coagulation↗

PubMed1994

Cerebral vasospasm caused by cisternal injection of polystyrene latex beads in rabbits is inhibited by a serine protease inhibitor.

During subarachnoid hemorrhage (SAH), coagulated blood in the subarachnoid space may be regarded as foreign by the immune system. To investigate how cerebral arteries are affected by activation of the host immune system, foreign body, polystyrene latex beads were injected into the cerebrospinal fluid (CSF) space of rabbits, and the caliber changes of the basilar arteries were studied for 7 days by angiography. Prolonged arterial narrowing peaking on day 2 was observed after cisternal injection of the beads. The increase in peak narrowing correlated with an increase in the number of beads injected. The course of the change in vessel caliber over 7 days was similar to that seen in cerebral vasospasm caused by SAH. Also investigated was the preventive effect of the synthetic serine protease inhibitor, FUT-175 on the arterial narrowing caused by the cisternal injection of the latex beads. The administration of FUT-175 significantly prevented latex beads-induced vasospasm (p < 0.01). The possible role of a non-specific immune response is discussed, and also the role of the serine protease cascades in the development of cerebral vasospasm.

Animals↗

PubMed1983

Anticoagulant activity of amino acid modified polystyrene resins: influence of the carboxylic acid function.

In previous papers, we have described the preparation and heparin-like properties of insoluble modified polystyrene resins. We now report results obtained with amino acid sulphamide resins that are virtually devoid of sulphonate groups and with resins bearing both sulphonate groups as well as amino acid sulphamides with spacers of various lengths. The absence of sulphonate groups does not affect the anticoagulant activity of the former type of resin. The biologic activity of the latter type of resin is dependent upon the length of the spacer between the amino and carboxylic acid functions. Maximal anticoagulant potency is attained with a spacer consisting of three methylene groups. Biologic activity is reduced with spacers that are less than or greater than this critical size.

Anticoagulants↗

PubMed1984

Adsorption of purified thrombin or antithrombin III for two insoluble anticoagulant polystyrene derivatives: II. Competition with the other plasma proteins.

In the preceding paper, we described results concerning the adsorption of purified thrombin and antithrombin III on two insoluble anticoagulant polystyrene derivatives. We now report similar results obtained in a plasma system. In each case, the purified protein was mixed with fresh platelet poor plasma in order to maintain the same concentrations of all the other plasma proteins. The thrombin molecule was modified by alkyl phosphorylation of the active serine site prior to mixing with plasma. The adsorption of antithrombin was found to be reduced 8 to 9 times when the protein solution was substituted by diluted plasma. In contrast, the thrombin adsorption only depends on the substituents bound on the polymeric chain. These results are supported by those of the study of the competition between purified antithrombin and albumin.

Adsorption↗

PubMed1984

Catalysis of the generation of thrombin-antithrombin complex by insoluble anticoagulant polystyrene derivatives.

The inhibition of thrombin by antithrombin III is known to be accelerated by heparin through the formation of complexes between the muccopolysaccharide and both proteins. In the preceding papers, we reported that polystyrene derivatives absorb thrombin and its inhibitor with a higher affinity for the protease than for the antiprotease. These complexes are responsible for the catalysis of the generation of thrombin-antithrombin complex which was observed either with purified proteins or in plasma. The protease-antiprotease complex has an affinity for the polymer surface which is higher than that of antithrombin but lower than that of thrombin. Therefore, the thrombin-antithrombin complex generated on the insoluble material is desorbed by thrombin and a catalytic anticoagulant effect can be observed with these polymers.

Anticoagulants↗