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PubMed2000

Testing of platelet deposition on polystyrene surface under flow conditions by the cone and plate(let) analyzer: role of platelet activation, fibrinogen and von Willebrand factor.

Recently, we described a method of testing platelet deposition on extracellular matrix under flow conditions. The method was used for assessment of platelet function in various platelet disorders, for monitoring of replacement and anti-platelet therapy. In the present study, we investigated platelet deposition on a polystyrene surface compared with that on extracellular matrix, under defined shear rates, using the original Cone and Plate(let) Analyzer. A correlation of adhesion rate (surface coverage) and aggregate formation (average size) of platelets from normal citrated blood between polystyrene and extracellular matrix was observed. Blocking of von Willebrand factor binding to glycoprotein Ib by a recombinant von Willebrand factor fragment substantially decreased platelet adhesion to both surfaces. Blocking of GPIIb-IIIa by Arg-Gly-Asp-Ser peptide prevented platelet adhesion to the polystyrene while an extensive adhesion of single platelets to extracellular matrix was observed. Furthermore, platelet adhesion to polystyrene but not to extracellular matrix was completely inhibited by platelet inactivation with prostaglandin E(1). Platelets from patients with severe von Willebrand disease yielded very low adhesion to both polystyrene and extracellular matrix. The addition of von Willebrand factor to the blood of these patients or pre-coating of polystyrene surface with von Willebrand factor restored the ability of platelets to adhere and aggregate on the surface. Platelets from patients with Glanzmann's thrombasthenia and afibrinogenemia adhered to extracellular matrix (with defective aggregate formation), while they failed to adhere to the polystyrene. Fibrinogen added to afibrinogenemia blood or pre-coating of the polystyrene with fibrinogen restored the ability of platelets to adhere and aggregate on the surface. In conclusion, the polystyrene surface, like extracellular matrix, can be used to assess platelet function disorders taking in account that platelet deposition on polystyrene under flow is absolutely dependent on platelet activation and on the presence of fibrinogen, von Willebrand factor, and their receptors.

Afibrinogenemia↗

PubMed2002

Periodate-treated, non-anticoagulant heparin-carrying polystyrene (NAC-HCPS) affects angiogenesis and inhibits subcutaneous induced tumour growth and metastasis to the lung.

Periodate-treated, non-anticoagulant heparin-carrying polystyrene consists of about ten periodate-oxidized, alkaline-degraded low molecular weight-heparin chains linked to a polystyrene core and has a markedly lower anti-coagulant activity than heparin. In this study, we evaluated the effect of non-anticoagulant heparin-carrying polystyrene on tumour growth and metastasis. Non-anticoagulant heparin-carrying polystyrene has a higher activity to inhibit vascular endothelial growth factor-165-, fibroblast growth factor-2- or hepatocyte growth factor-induced human microvascular endothelial cell growth than heparin, ten periodate-oxidized-heparin and ten periodate-oxidized-low molecular weight-heparin, which is probably due to the heparin-clustering effect of non-anticoagulant heparin-carrying polystyrene. Non-anticoagulant heparin-carrying polystyrene inhibited human microvascular endothelial cell, B16 melanoma and Lewis lung cancer cell adhesion to Matrigel-coated plates. Non-anticoagulant heparin-carrying polystyrene also showed strong inhibitory activities in the tubular formation of endothelial cells on Matrigel and B16-melanoma and Lewis lung cancer cell invasion in a Matrigel-coated chamber assay. In vivo studies showed that growth of subcutaneous induced tumours and lung metastasis of B16-melanoma and Lewis lung cancer cells were more effectively inhibited by non-anticoagulant heparin-carrying polystyrene than ten periodate-oxidized-heparin and ten periodate-oxidized-low molecular weight-heparin. Furthermore, non-anticoagulant heparin-carrying polystyrene markedly reduced the number of CD34-positive vessels in subcutaneous Lewis lung cancer tumours, indicating a strong inhibition of angiogenesis. These results suggest that non-anticoagulant heparin-carrying polystyrene has an inhibitory activity on angiogenesis and tumour invasion and may be very useful in cancer therapy.

Angiogenesis Inhibitors↗

PubMed2005

Osteoblasts generate harder, stiffer, and more delamination-resistant mineralized tissue on titanium than on polystyrene, associated with distinct tissue micro- and ultrastructure.

UNLABELLED: This study revealed that osteoblasts generate harder, stiffer, and more delamination-resistant mineralized tissue on titanium than on the tissue culture polystyrene, associated with modulated gene expression, uniform mineralization, well-crystallized interfacial calcium-phosphate layer, and intensive collagen deposition. Knowledge of this titanium-induced alteration of osteogenic potential leading to enhanced intrinsic biomechanical properties of mineralized tissue provides novel opportunities and implications for understanding and improving bone-titanium integration and engineering physiomechanically tolerant bone. INTRODUCTION: Bone-titanium integration is a biological phenomenon characterized by continuous generation and preservation of peri-implant bone and serves as endosseous anchors against endogenous and exogenous loading, of which mechanisms are poorly understood. This study determines the intrinsic biomechanical properties and interfacial strength of cultured mineralized tissue on titanium and characterizes the tissue structure as possible contributing factors in biomechanical modulation. MATERIALS AND METHODS: Rat bone marrow-derived osteoblastic cells were cultured either on a tissue culture-grade polystyrene dish or titanium-coated polystyrene dish having comparable surface topography. Nano-indentation and nano-scratch tests were undertaken on mineralized tissues cultured for 28 days to evaluate its hardness, elastic modulus, and critical load (force required to delaminate tissue). Gene expression was analyzed using RT-PCR. The tissue structural properties were examined by scanning electron microscopy (SEM), collagen colorimetry and localization with Sirius red stain, mineral quantification, and localization with von Kossa stain and transmission electron microscopy (TEM). RESULTS: Hardness and elastic modulus of mineralized tissue on titanium were three and two times greater, respectively, than those on the polystyrene. Three times greater force was required to delaminate the tissue on titanium than that on the polystyrene. SEM of the polystyrene culture displayed a porous structure consisting of fibrous and globular components, whereas the titanium tissue culture appeared to be uniformly solid. Cell proliferation was remarkably reduced on titanium. Microscopic observations revealed that the mineralized tissue on titanium was composed of uniform collagen-supported mineralization from the titanium interface to the outer surface, with intensive collagen deposition at tissue-titanium interface. In contrast, tissue on the polystyrene was characterized by collagen-deficient mineralization at the polystyrene interface and calcium-free collagenous matrix formation in the outer tissue area. Such characteristic microstructure of titanium-associated tissue was corresponded with upregulated gene expression of collagen I and III, osteopontin, and osteocalcin mRNA. Cross-sectional TEM revealed the apposition of a high-contrast and well-crystallized calcium phosphate layer at the titanium interface but not at the polystyrene interface. CONCLUSIONS: Culturing osteoblasts on titanium, compared with polystyrene, enhances the hardness, elastic modulus, and interfacial strength of mineralized tissue to a higher degree. Titanium per se possesses an ability to alter cellular phenotypes and tissue micro- and ultrastructure that result in enhanced intrinsic biomechanical properties of mineralized tissue.

Animals↗

PubMed1998

Uterotrophic assay of two concentrations of migrates from each of 23 polystyrenes administered orally (by gavage) to immature female Wistar rats.

The Styrene Steering Committee (SSC) of the European Chemical Industry Council (CEFIC) sponsored this work to address any concern that styrene dimers and trimers that might migrate from polystyrene containers into food could possess some estrogenic activity and thus possibly affect human health. All phases of the study were conducted in conformance with GLP regulations and without knowledge of the oligomer migrates tested. All activities were managed and audited under a third-party contract between the SSC and Argus International. Low and high doses of the styrene oligomer migrates of 23 polystyrene samples [i.e. 9 general purpose polystyrenes (GPPS), 8 high impact polystyrenes (HIPS) and 6 expandable polystyrenes (EPS)] were tested for estrogenicity in an in vivo uterotrophic assay (immature female rat model). This model is considered to be the "gold standard" for use in screening for estrogenic effects because it evaluates both direct and indirect potential effects. The two concentrations of migrates of each of the 23 polystyrenes tested were selected to simulate daily human consumption of a low and high amount of food. Representative dimer and trimer concentrations were obtained in conformance with EEC Council Directives and calculated to be at levels simulating human consumption of 0.5 or 5 kg of food for the GPPS and the HIPS samples and of 0.5 or 3.15 kg of food for the EPS samples, respectively. The study was conducted in a series of three blocks. Each block included concurrent untreated control (negative control), vehicle control (25% ethanol, 20 ml/kg/day) and positive control (diethylstilbestrol-dipropionate, DES-DP, 5 micrograms/kg/day) groups, and low and high doses of each of 7 (1 block) or 8 (2 blocks) polystyrene oligomer migrates. Each group in each block consisted of 10 immature Wistar (Chbb: THOM-SPF) female rats. Beginning when the rats were 22 +/- 1 days of age, each rat was appropriately handled (untreated control group) or administered twice daily oral (gavage) dosages of the vehicle, positive control agent or one of the two doses of the migrates of each polystyrene for 4 consecutive days and then sacrificed at 26 +/- 1 days of age. The uterus of each rat was weighed, and the uterine weight was compared with the terminal body weight. The positive control agent (DES-DP, 5 micrograms/kg/day) significantly increased both absolute and relative (to terminal body weight) uterine weights, as compared to the untreated and vehicle control group values in each block, demonstrating sensitivity and response of the animals to an estrogenic agent. None of the 23 polystyrene oligomer migrates tested at low and high doses demonstrated biologically important or statistically significant differences from the untreated or vehicle control group values for absolute or relative (to body weight) uterine weights. Based on these data, it is concluded that low and high doses of the 23 polystyrene oligomer migrates tested did not induce an estrogenic response.

Animals↗

PubMed1998

Assessment of polystyrene extract for estrogenic activity in the rat uterotrophic model and an in vitro recombinant receptor reporter gene assay.

The purpose of the study was to determine whether polystyrene used in food-contact applications would elicit an estrogenic response when extracts simulating exaggerated conditions of use were subjected to in vivo and in vitro tests. A sample of polystyrene was subjected to extraction conditions that simulate, or exaggerate, the actual food-contact uses of polystyrene to maximize the amount of low molecular weight polystyrene extractables. The food-simulating solvent and the time and temperature conditions recommended by the Food and Drug Administration (FDA) were selected to maximize the level of extractable components from polystyrene. The extract was examined for its estrogenic response in vivo using the immature rat uterotrophic assay and in vitro using an estrogen receptor (ER)-mediated recombinant receptor reporter gene assay. In vivo, the uterine weights of juvenile female Sprague Dawley rats (10 rats/group) were determined after oral gavage exposure to the extract (two dosage levels: one represents the maximum potential daily human exposure to polystyrene extractables and the other represents one-tenth of the maximum exposure level), vehicle control (sesame oil), or positive control [diethylstilbestrol (DES), at 200 micrograms/kg body weight]. In addition, five treatment groups were dosed by subcutaneous injection of either estradiol (1, 50, and 500 micrograms/kg body weight) or DES (2 and 200 micrograms/kg body weight). Dosing began on postnatal day (pnd) 21 and continued daily through pnd 23. Body weights were collected at study initiation (pnd 21) and at necropsy (pnd 24). Body weights were not different statistically between treatment groups at study initiation or at necropsy. Uterine wet weights and uterine weights relative to body weights were significantly increased (p < 0.05) for estradiol at 50 and 500 micrograms/kg, DES at 2 and 200 micrograms/kg, and DES at 200 micrograms/kg (oral) over vehicle control. The polystyrene extract had no effect on uterine wet weight or uterine weights relative to body weights at either level tested. An in vitro recombinant estrogen receptor/reporter gene assay that involved transiently transfecting MCF-7 human breast cancer cells with the chimeric human ER, Ga14-HEGO, consisting of the yeast Ga14 DNA binding domain linked to the ligand binding domain of the human ER and a Ga14 response element (17mer)-regulated reporter gene (17m5-G-Luc) was employed. Dose-dependent induction of the reporter gene, 17m5-G-Luc, was observed with the positive control, 17 beta-estradiol (E2). Induction of greater than 100-fold was obtained following incubation of transfected MCF-7 cells with 10 nM E2 for 24 hours. No induction of reporter gene activity was observed with the polystyrene extracts dissolved in dimethylsulfoxide (0.01, 0.1 or 0.01 mg/ml) using the same assay conditions. These results indicate that polystyrene extract does not elicit ER-mediated activity using the Ga14-HEGO/17m5-G-Luc recombinant receptor/reporter gene assay. In conclusion, extracts from polystyrene produced no estrogenic response in either the rat uterotrophic assay or the MCF-7 cell assay for estrogen receptor-mediated activity.

Animals↗

PubMed2004

Interaction of apo cytochrome c with sulfonated polystyrene nanoparticles.

Stable nanoparticle dispersion in aqueous solutions was obtained with partially sulfonated polystyrene. The hydrophobic association of the backbone chains and phenyl groups is balanced by the electrostatic repulsion of the sulfonate groups on the particle surface. The size distribution of the sulfonated polystyrene particles in relation to concentration, degree of sulfonation and chain length, and pH was characterized by dynamic laser light-scattering. The structure and morphology of the particles were characterized with fluorescence and atom force microscopy. Highly sulfonated polystyrene particles can form large complex particles with positively charged protein, apo cytochrome c. Dynamic laser light-scattering and atom force microscopy studies show that the size and distribution of the complex particles depend on the relative amount of apo cytochrome c and sulfonated polystyrene. When sulfonated polystyrene is in excess, apo cytochrome c interacts with sulfonated polystyrene particles forming stable complexes and excessive sulfonated polystyrene particles bind to the periphery of the complexes preventing them from further aggregation. When apo cytochrome c is in excess, apo cytochrome c links the complexes forming much larger particles. Fluorescence study demonstrates that the hydrophobicity/hydrophility of the complex particles is relative to the ratio of apo cytochrome c and sulfonated polystyrene, degree of sulfonation, and pH. Apo cytochrome c not only can neutralize the negative charges on the surface of sulfonated polystyrene particles, but may also insert into the cores disrupting the original structure of sulfonated polystyrene particles.

Apoproteins↗

PubMed2005

The surface pressure dynamics and appearance of mixed monolayers of cholesterol and different sized polystyrenes at an air-water interface.

Synthetic polymers are increasingly being used in situations where they are designed to interact with biological systems. As a result, it is important to investigate the interactions of the polymers with biochemicals. We have used cholesterol, as an example of an important biological surfactant component, to study its interactions with polystyrene. Mixed monolayers of cholesterol and one of two different molecular weight polystyrenes were formed at an air-water interface to investigate their interactions and to determine whether the size of the polystyrene affected the interaction. The pressure-area (pi-A) isocycles of mixed monolayers of cholesterol and polystyrene MW 2700 or polystyrene MW32700 showed that strongest attractive interactions occur at high surface pressures and in polystyrene rich films. The excess area and excess free energy of mixing were most negative at high surface pressures and at high mole fraction of polystyrene. The most stable mixed monolayers were formed with X(PS2700) = 0.9 and X(PS32700) = 0.09. Microscopic observation of the mixed monolayers of cholesterol and polystyrene showed the formation of stable islands in the cholesterol/polystyrene mixtures. These observations, the nature of the inflection points in the isocycles, and the anomalous changes in free energy lead us to conclude that there is a stable rearrangement of polystyrene into compact islands when it is mixed with cholesterol. Any excess cholesterol is excluded from these islands and remains as a separate film surrounding the islands.

Air↗

PubMed2000

Effect of salivary secretory IgA on the adhesion of Candida albicans to polystyrene.

Attachment of Candida albicans to plastic materials of dental prostheses or to salivary macromolecules adsorbed on their surface is believed to be a critical event in the development of denture stomatitis. In an earlier study, it was shown that adhesion of C. albicans to polystyrene, a model system to study the adhesion of C. albicans to plastic materials, can be partially inhibited with an mAb directed against cell wall polysaccharides of C. albicans. In the present study, the role of whole saliva in the adhesion of C. albicans to polystyrene has been investigated, and three mAbs directed against epitopes of cell wall mannoproteins have been used to mimic the inhibitory effect observed with salivary secretory IgA (sIgA) on the adhesion of C. albicans to polystyrene. In the absence of whole saliva, adherence of C. albicans 3153 increased with germination. However, the presence of whole saliva enhanced the adhesion to polystyrene of C. albicans 3153 yeast cells but decreased the adhesion of germinated cells. The enhancement of adhesion of yeast cells to polystyrene mediated by saliva was confirmed with an agerminative mutant of C. albicans 3153. The inhibition of the adhesion of C. albicans 3153 germ tubes to polystyrene was due to the salivary sIgA since sIgA-depleted saliva enhanced the adhesion of C. albicans 3153 to polystyrene. The inhibitory effect mediated by sIgA was not related to the inhibition of germination but to the blockage of adhesins expressed on the cell wall surface of the germ tubes. The three mAbs studied reduced the adhesion of C. albicans 3153 to polystyrene at levels equivalent to those for purified sIgA. The highest reduction in the adhesion was obtained with the IgA mAb N3B. The best results were obtained when the three mAbs were combined. The results suggest that whole saliva plays a different role in the adhesion of C. albicans to polystyrene depending on the morphological phase of C. albicans. These results may give new insights into the conflicting role of saliva in the adhesion of C. albicans to plastic materials of dental prostheses.

Antibodies, Monoclonal↗

PubMed1996

Effect of monoclonal antibodies directed against Candida albicans cell wall antigens on the adhesion of the fungus to polystyrene.

The adhesion of Candida albicans to polystyrene and the effect of three monoclonal antibodies (mAbs) reactive with C. albicans cell wall surface antigens on this process was assessed in vitro with several C. albicans strains. In the absence of mAbs, adhesion of C. albicans to polystyrene increased in parallel with germ-tube formation. However, the growth of the strains in the yeast phase at 25 degrees C or the use of an agerminative mutant inhibited adhesion to polystyrene. Serotype A and B strains showed similar kinetics of adhesion to polystyrene and no statistically significant differences in germination or adhesion were observed when strains from the two serotypes were compared. The three mAbs had different effects on both germination and adhesion of C. albicans. mAbs 3D9 showed no influence on either germination or adhesion to polystyrene in two C. albicans strains. mAb B9E decreased both adhesion (45.6%) and filamentation (52.6%), and mAb 21E6 decreased filamentation (34.0%) but enhanced adhesion by 23.3%. This enhancement was also observed with the agerminative mutant and it was dose-dependent. It was not related to the binding capacity of the MAb to polystyrene nor to an increase in cell surface hydrophobicity of the antibody-treated cells. In conclusion, both growth phases of C. albicans can adhere to polystyrene, although the conditions for this process seem to be different in each phase. The two types of adhesion of C. albicans to polystyrene might have a role in the colonization of medical implants. The disparate effects shown by mAbs directed against cell wall mannoproteins of C. albicans on the adhesion of the fungus to polystyrene should be taken into consideration when designing strategies to block the adhesion of C. albicans to plastic materials with mAbs.

Animals↗

PubMed1998

Preparation and analysis of styrene oligomers containing migrates from various polystyrenes used in food packaging.

An oligostyrene-like product (F2L5250) was reported to have estrogen-like activity (statistically significant increases in means for absolute uterine weight and the ratios of the uterine weight to terminal body weight) in juvenile female rats provided a dietary concentration of 100 ppm F2L5250 for four consecutive days. The highest no-effect-level (NOEL) for estrogenic activity was 80 ppm in the diet, corresponding to a daily intake of 13.3 mg F2L5250/kg. Although it is unlikely that such estrogenic tetramers would occur in commercial polystyrene, the Styrene Steering Committee (SSC) of the European Chemical Industry Council (CEFIC) sponsored the current extensive project to address any concern that human consumption of styrene oligomers migrating from polystyrene containers into food, e.g., from packaged yoghurt, or from the use of EPS coffee cups and related products, might affect human health. To ensure confidentiality and compliance with the highest scientific and regulatory standards, the entire project was conducted without knowledge of the oligomer migrates tested, and all activities were managed and audited under a contract between the SSC and a third party, Argus International. This paper describes the preparation and analyses of the 23 representative polystyrenes [9 general purpose polystyrenes (GPPS), 8 high impact polystyrenes (HIPS) and 6 expandable polystyrenes (EPS)] evaluated for estrogenicity in an in vivo uterotrophic assay in immature female rats. The polystyrene samples were chosen to represent food packaging applications. They were obtained from participating European Polystyrene Manufacturers, coded at the TNO Nutrition and Food Research Institute, Utrecht, The Netherlands (TNO) and sent to BASF, Ludwigshafen, Germany for preparation of test bars (GPPS and HIPS) or test foam parts (EPS). The prepared polystyrene test bars or test foam parts were submitted to elution with 50% aqueous (v/v) ethanol for 10 days at 40 degrees C, a procedure which simulates an exposure at ambient temperature for several weeks and represents an exaggeration in comparison with yogurt, for which directive 85/572/EEC1 defines 3% aqueous acetic acid as the official food simulant. To further exaggerate the potential concentration of the possible migrates, the surface/volume ratio selected for elution was the maximum experimentally possible, i.e., approximately 56 dm2/kg food for the GPPS and HIPS bars and approximately 38 dm2/kg food for the EPS foam, representing a multiple of approximately 9 (GPPS and HIPS) and 6 (EPS), times the conventional surface/volume ratio of 6 dm2/kg. These obtained styrene oligomer migrates were then diluted to 25% aqueous (v/v) ethanol, a concentration that could be tolerated by the test animals. After dilution, the low and high concentrations represented multiples of 0.5 and 4.6 (GPPS and HIPS) and 0.5 and 3.2 (EPS) the conventional surface/volume ratio, respectively. These levels simulated daily human consumption of 500 or 5,000 g of food for the GPPS and HIPS samples and of 500 or 3,150 g of food for the EPS samples, respectively. The results of the homogeneity, stability and concentration analyses of the styrene dimers and trimers in the migrates indicated that the concentrations of migrants were highest as the result of 50% aqueous ethanol extraction of HIPS test bars followed by GPPS test bars and EPS test foam parts.

Animals↗

PubMed1995

Binding of beta 2 glycoprotein I to activated polystyrene and its recognition by human IgG autoantibodies.

Beta 2 glycoprotein I (apolipoprotein H, beta 2GPI) is involved in the formation of epitope(s) recognized by clinically relevant autoantibodies from patients with antiphospholipid syndrome. We studied the binding of beta 2GPI to chemically activated polystyrene in a microtitre plate format. Adsorption isotherms (at 37 degrees C) were generated for beta 2GPI on activated polystyrene and on unactivated polystyrene, with both human serum antibodies and rabbit polyclonal IgG antibodies as probes, and horseradish peroxidase (HRP)-tagged anti-IgG to detect binding. Additionally, beta 2GPI was biotinylated and isotherms were developed by using HRP-streptavidin as the recognition sequence. Human serum autoantibodies, which did not precipitate beta 2GPI in solution, yielded a characteristic chemisorption isotherm on activated polystyrene but did not recognize beta 2GPI bound to untreated polystyrene. The rabbit IgG, which did precipitate beta 2GPI in solution, detected beta 2GPI bound to both activated polystyrene and, to a lesser extent, to untreated polystyrene. The binding of beta 2GPI to untreated polystyrene was confirmed by the use of biotinylated beta 2GPI. To assess the prevalence of IgG anti-beta 2GPI autoantibodies, we surveyed 113 sera submitted to our laboratory for anticardiolipin antibody (aCL) testing. Only nine (8%) had anti-beta 2GPI activity greater than two standard deviations above the mean for those sera in which aCL activity was within normal limits. We conclude that epitope presentation of beta 2GPI for human autoantibody binding is dependent on surface properties of the polystyrene, and that beta 2GPI autoantibodies are found only in a subpopulation of sera positive for aCL.

Adsorption↗

PubMed2006

Synthesis and characterization of uniform radiopaque polystyrene microspheres for X-ray imaging by a single-step swelling process.

Uniform radiopaque polystyrene microspheres of approximately 2.3 +/- 0.2 microm were prepared by a single-step swelling of 2.3 +/- 0.2 microm polystyrene template microspheres, dispersed in an aqueous solution with methylene chloride emulsion droplets containing 2,3,5-triiodobenzoylethyl ester. After completing the swelling process, the methylene chloride was evaporated in order to lock the 2,3,5-triiodobenzoylethyl ester in the polystyrene microspheres. The influence of the weight ratio [2,3,5-triiodobenzoylethyl ester]/[polystyrene] on the % of entrapped 2,3,5-triiodobenzoylethyl ester was elucidated. Characterization of the radiopaque polystyrene microspheres was accomplished by light microscope, FTIR, TGA, SEM, XPS, and elemental analysis. The radiopacity of the microspheres was demonstrated by an imaging technique based on X-ray absorption usually used in hospitals. This novel method of encapsulation of 2,3,5-triiodobenzoylethyl ester within polystyrene microspheres by a single-step swelling process may be used as a model for encapsulation of various hydrophobic radiopaque drugs within uniform polystyrene template particles of various diameters for different X-ray imaging needs, e.g., blood pool, body organs, embolization, dental composition, implants, protheses, and nanocomposites.

Crystallization↗

PubMed1986

Use of monoclonal antibodies to detect conformational alterations in lactate dehydrogenase isoenzyme 5 on heat denaturation and on adsorption to polystyrene plates.

A monoclonal antibody (mAb) MF30 (IgGl) against human lactate dehydrogenase isoenzyme 5 (HLDH5) was prepared. MF30 was found to bind with high specificity to HLDH5 when the enzyme was adsorbed onto a polystyrene plate but did not recognize the isoenzyme when in solution. The isoenzymes HLDH1, HLDH2 and HLDH3 adsorbed onto polystyrene were not recognized by mAb MF30. Heat-treated HLDH5 (heated at 70 degrees C, pH 7.5 for 45 sec) behaved towards MF30 in the same way as the untreated isoenzyme, i.e. interaction between them took place only after the denatured isoenzyme had been adsorbed onto an ELISA plate. A second mAb, designated 2/66, prepared against porcine lactate dehydrogenase isoenzyme 5 (PLDH5), was found to interact with the porcine isoenzyme when in solution as well as when adsorbed onto polystyrene. However, no such interaction occurred after the isoenzyme had been subjected to heat treatment as above. The mAb 2/66 was found to cross-react fully with the human isoenzyme HLDH5 both in solution and when adsorbed onto polystyrene; however, as in the case of the porcine isoenzyme, all such recognition was lost upon heat denaturation. The above findings suggest that the adsorption of HLDH5 onto a polystyrene surface is accompanied by a conformational change. Denaturation of the enzyme by heat seems to lead to the appearance of a conformation differing in its antigenic pattern from that of the adsorbed enzyme. The data suggest that the mAbs MF30 and 2/66 recognize two different antigenic sites of HLDH5. The antigenic site which is recognized by 2/66 and is present in the native enzyme both when in solution and when adsorbed onto polystyrene disappears on heating. The other antigenic determinant is recognized by mAb MF30 when the enzyme is adsorbed onto a polystyrene surface either before or after heat treatment. This study illustrates the way in which appropriate mAbs might possibly be used as probes for the detection of conformational alterations occurring in proteins under various conditions.

Adsorption↗

PubMed1995

In vitro binding of lithium using the cation exchange resin sodium polystyrene sulfonate.

Sodium polystyrene sulfonate, a cation exchange resin, should be useful in the treatment of lithium overdosage. This in vitro study was conducted to assess the ability of sodium polystyrene sulfonate to bind lithium, effects of pH on binding, binding efficacy in comparison to charcoal, and affinity for lithium versus potassium. Stock solutions of lithium were added to fixed amounts of sodium polystyrene sulfonate and charcoal. Lithium and potassium concentrations in supernatant were measured by flame photometry. Increasing concentrations of sodium polystyrene sulfonate bound more lithium. Changes in pH had little effect on lithium binding. Lithium is bound to sodium polystyrene sulfonate more readily than to charcoal. Potassium is preferentially bound to sodium polystyrene sulfonate over lithium. Sodium polystyrene sulfonate may provide a useful therapeutic modality in the treatment of lithium overdosage.

Binding Sites↗

PubMed1992

Lithium absorption prevented by sodium polystyrene sulfonate in volunteers.

STUDY OBJECTIVE: To determine if sodium polystyrene sulfonate prevents absorption of lithium in human beings. DESIGN: Prospective, crossover study. TYPE OF PARTICIPANTS: Healthy volunteers age 22 to 34 years (three women and three men). INTERVENTIONS: After an eight-hour fast, subjects ingested 0.5 mEq/kg (18.5 mg/kg) lithium carbonate. One hour later, they ingested either 857 mg/kg sodium polystyrene sulfonate in 4 mL water/g sodium polystyrene sulfonate (experimental) or an equal volume of water without sodium polystyrene sulfonate (control). MEASUREMENTS AND MAIN RESULTS: Serum lithium levels were drawn zero, one, two, three, four, six, eight, ten, 12, and 24 hours after lithium ingestion. The sodium polystyrene sulfonate group had a smaller mean area under the serum concentration curve (11.6 +/- 1.0 mEq/L.hr versus 13.6 +/- 1.5 mEq/L.hr, P < .001) and lower mean highest measured lithium level (0.85 +/- 0.11 mEq/L versus 1.05 +/- 0.10 mEq/L, P < .05) compared with the control group. There was no significant difference in 24-hour urine lithium excretion or in serum sodium and potassium levels. CONCLUSION: Sodium polystyrene sulfonate administration decreased absorption of lithium after a lithium carbonate overdose. Sodium polystyrene sulfonate may be useful clinically for gastric decontamination after lithium overdoses.

Absorption↗

PubMed1970

The preparation and properties of yeast beta-fructofuranosidase chemically attached to polystyrene.

1. A process is described for the chemical attachment of an enzyme to the surface of a polystyrene matrix. 2. By this process yeast beta-fructofuranosidase was chemically attached to the surface of both polystyrene beads and polystyrene tubes. 3. The kinetics of sucrose hydrolysis by beta-fructofuranosidase and polystyrene-supported beta-fructofuranosidase were compared. 4. The pH-activity curve of the polystyrene-supported enzyme shows a marked difference from that of the free enzyme in solution. 5. The inhibitor dissociation constant with respect to tris is increased, whereas the inhibitor dissociation constant with respect to aniline is decreased when the enzyme is attached to polystyrene. 6. Differences between the properties of the bound and free enzyme are discussed in terms of a micro-environmental effect arising from the hydrophobic nature of the polystyrene support.

Aniline Compounds↗

PubMed1975

New useful reagents for peptide synthesis. Insoluble active esters of polystyrene-bound 1-hydroxybenzotriazole.

Insoluble 1-hydroxbenzotriazole-bound polystyrene was prepared through a series of chemical modifications of commercially available polystyrene. Reaction of 3-nitro-4-chlorobenzyl alcohol or of 3-nitro-4-chlorobenzyl bromide with polystyrene in the presence of aluminium trichloride yielded (3-nitro-4-chloro)benzylated polystyrene. Upon reaction with hydrazine it was converted to (3-nitro-4-hydrazine) benzylated polystyrene which was cyclized, by acidolysis, to yield 1-hydroxybenzotriazole-bound polystyrene. This was coupled, using N, N' -dicyclohexylcarbodiimide as the coupling agent, to many N-blocked amino acid derivatives, yielding polymeric polystyrene-bound active esters. Such derivatives are highly reactive and their efficacy in the synthesis of several peptides, including that of the tetrapeptide Boc-L-Leu-L-leu-L-Val-0bzl-L-Tyr-0Bzl and of thyrotropin-releasing hormone was demonstrated.

Dipeptides↗

PubMed1988

Sensitive sandwich enzyme immunoassay of human growth hormone (hGH) in serum and urine using monoclonal antibody-coated polystyrene balls.

A sensitive sandwich enzyme immunoassay for human growth hormone (hGH) using monoclonal antibody is described. A monoclonal anti-hGH IgG-coated polystyrene ball was incubated with hGH and subsequently with affinity-purified rabbit anti-hGH Fab'-horseradish peroxidase conjugate. Peroxidase activity bound to the polystyrene ball was assayed by fluorimetry using 3-(4-hydroxyphenyl) propionic acid as a substrate. The detection limits of hGH in serum and urine were 1.5 ng/l using 20 microliters of serum and 0.2 ng/l using 0.15 ml of urine, respectively. The specificity and assay precision were satisfactory. hGH levels in serum and urine determined by the present sandwich enzyme immunoassay using monoclonal anti-hGH IgG-coated polystyrene balls were well correlated to those determined by the previous sandwich enzyme immunoassay using rabbit anti-hGH IgG-coated polystyrene balls. Levels of hGH in urine collected as first morning voids from healthy subjects aged 19-28 yr were 6.4 +/- 3.2 (SD) ng/g creatinine. However, the present assay gave lower hGH levels than the previous assay. This was at least partly explained by the fact that hGH in urine was less efficiently bound to monoclonal anti-hGH IgG-polystyrene balls than standard hGH, while the binding of hGH in urine and standard hGH to rabbit anti-hGH IgG-coated polystyrene balls was equally efficient. In addition, gel filtration showed that 22K hGH, a major component, in urine was less efficiently bound to monoclonal anti-hGH IgG-coated polystyrene balls than standard 22K hGH. The nature of hGH in serum and urine remains to be investigated.

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