Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Styrenes”

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 1,009 records · Page 56Linked to original sources
PubMed1995

Influence of GSTM1 genotype on sister chromatid exchange induction by styrene-7,8-oxide and 1,2-epoxy-3-butene in cultured human lymphocytes.

Glutathione S-transferase M1 (GSTM1), catalyzing the conjugation of various reactive molecules with glutathione (GSH), shows genetic polymorphism in humans. Almost half of all Caucasians lack the GSTM1 gene, being theoretically at a higher risk from the toxic effects of substrates for GSTM1. The purpose of the present study was to investigate whether the GSTM1 genotype of lymphocyte donors influences the in vitro induction of sister chromatid exchanges (SCEs) by styrene-7,8-oxide (SO) and 1,2-epoxy-3-butene (MEB), the epoxide metabolites of styrene and butadiene respectively and potential substrates for GSTM1. SCEs induced after a 48 h treatment (started 24 h after culture initiation) by two different concentrations of SO (50 and 150 microM) and MEB (50 and 250 microM) were analyzed in cultured (72 h) lymphocytes of six GSTM1 null (gene deleted) and six GSTM1-positive (gene present) donors. Both SO and MEB were found to clearly increase SCEs. The GSTM1 genotype had no influence on SCE induction by SO. In contrast, MEB produced a higher level of SCEs among the GSTM1 null than GSTM1-positive samples. At 250 microM MEB, the GSTM1 null donors showed 31% more induced SCEs (on average seven more SCEs per cell) than the GSTM1-positive donors (P = 0.02, acetone treatment as the reference). Furthermore, the GSTM1 null genotype was associated with a slight decrease in mitotic index and replication index, regardless of the treatment. The results suggest that GSTM1-mediated GSH conjugation is an important detoxification pathway for MEB, but not for SO, in cultured human lymphocytes.

Adult↗
PubMed1996

7-Alkylguanine adducts of styrene oxide determined by 32P-postlabeling in DNA and human embryonal lung fibroblasts (HEL).

The modified 32P-postlabeling method was used for the detection of N-7-(2-hydroxy-phenylethyl) guanine adducts in DNA and human embryonal lung (HEL) cells treated in vitro with styrene oxide (SO). The total recovery of 7-alkylguanine adducts of styrene oxide in DNA analysed by 32P-postlabeling assay was 4.1 +/- 0.6%. The disappearance of 7-alkyldeoxyguanosine monophosphate adducts from SO-modified DNA at 37 degrees C showed a half-life of 19 h. The levels of 7-alkylguanine DNA adducts and single-strand breaks (SSBs) in DNA were determined in HEL cells treated with SO for 3 and 18 h. In the 3 h treatment there was a concentration-dependent increase of both 7-alkylguanine adducts and SSBs in DNA (r = 0.98, P = 0.012 and r = 0.99, P = 0.003, respectively). We found a significant correlation between 7-alkylguanine DNA adducts and SSBs in DNA (r = 0.98, P = 0.011). In HEL cells approximately 3-fold higher levels of both 7-alkylguanine DNA adducts and SSB in DNA were found after the SO (100 microM) treatment for 3 h than after the treatment for 18 h. A significant concentration-dependent increase was found only for SSB ( r = 0.95, P = 0.024) in the 18 h treatment with SO. There was no significant correlation between 7-alkylguanine adducts and SSBs (r = 0.72, P = 0.15). Our data suggest relatively fast removal of both 7-alkylguanine adducts of SO and DNA SSBs.

Autoradiography↗
PubMed1997

32P-postlabelling analysis of isomeric 7-alkylguanine adducts of styrene oxide.

Styrene 7,8-oxide, which reacts preferentially at the N-7 position of guanine, yielded two pairs of diastereomers 7-(1'-hydroxy-2'-phenylethyl)-dGMP (the alpha-isomer) and 7-(2-hydroxy-2-phenylethyl)-dGMP (the beta-isomer) on reaction with deoxyguanosine-3'-monophosphate (3'-dGMP). The alpha- and beta-isomers were formed in the ratio 32:68. T4 polynucleotide kinase preferentially mediated labelling of diastereomers corresponding to the beta-isomer. The beta-diastereomers showed a labelling efficiency of 52%, whereas the alpha-isomers showed a labelling efficiency of 4%. Molecular modelling experiments showed intrinsic differences between the two isomers. The torsion angles of C8-N7-2'-Ar and C8-N7-2'-1' for the alpha-isomers were 149.9 degrees and -26.4 degrees, whereas the torsion angles of C-8-N7-1'-2' and N7-1'-2'-Ar for the beta-isomers were 105.3 degrees and 179.4 degrees. The consequent interatomic distance between one of the hydrogens on the alpha-carbon and the 3'-phosphate group on the sugar residue was 5.3 A in the alpha-isomer whereas the closest distance between the hydrogens attached to the alpha-carbon and 3'-phosphate group in the beta-isomer was 6.2 A. This arrangement probably leads to steric overcrowding at the 3'-phosphate group in alpha-isomers and these are less efficiently phosphorylated than beta-isomers. In in vitro styrene oxide-modified salmon testis DNA alpha- and beta-isomers of 7-alkylguanines were formed in the ratio 37:63. The recovery of two diastereomeric beta-isomers in a 32P-postlabelling assay was 14%, but one of the diastereomers was obtained in 3-fold greater yield than the second isomer.

Animals↗
PubMed2003

Styrene-7,8-oxide activates a complex apoptotic response in neuronal PC12 cell line.

Styrene-7,8-oxide (SO), the major in vivo metabolite of styrene, one of the most important plastic monomers worldwide, is classified as carcinogenic in humans and animals. Although the toxic effects of SO have been extensively documented in human lymphocytes, the molecular mechanisms responsible for SO-induced cell damage are still unknown. In the present study, we evaluated the effect of SO on growth and apoptosis, assessed by FACS and gel ladder analysis, in neuronal PC12 cell line. Our results demonstrate that SO triggered PC12 cell apoptosis in a dose- and time-dependent manner. PC12 apoptosis was associated with caspase-3 activation and modulation of the Bcl-2 family proteins. In addition, examination of the cytoskeleton showed that SO induced F-actin depolymerization and a rapid cell rounding before caspase-3 activation, suggesting that the changes in cell shape involving cytoskeletal structure are an early step in the apoptotic pathway. Therefore, SO triggers a complex apoptotic response consisting of a loss of cytoskeletal organization that precedes caspase-3 activation. These mechanisms may represent the molecular basis of the different SO sensitivity to tumor promotion among species and organs.

Animals↗
PubMed1996

Molecular analysis of styrene oxide-induced hprt mutation in human T-lymphocytes.

Styrene-7,8-oxide (SO), the mutagenic in vivo metabolite of the widely used chemical monomer styrene, has been classified as a probable human carcinogen (IARC, 1994). We examined mutations in the hypoxanthine-guanine phosphoribosyl transferase (hprt) gene of primary human T-lymphocytes exposed to 0.2 mM SO for 6 days in vitro. PCR amplification and direct DNA sequencing were used to identify 55 SO-induced mutations from two experiments in which the mutation frequencies increased 3.6 and 4.8 times respectively, and 44 control mutations from untreated T-cell cultures. Base substitutions were the dominating type of mutation in both groups, with 35 and 23 independent changes, of which nine and six respectively, have not previously been described in human T-cells. Frameshift mutations (+/-1 bp) and small deletions (2-200 bp) were less frequent and splicing mutations more frequent among the SO-induced than among the control mutations. In SO-treated mutants, base substitutions in the coding region occurred at 15 sites, nine of which were AT bp, and in the splice donor and acceptor regions six of 10 mutated sites were AT bp. Altogether six independent mutations were found at site 539 in cells from the two SO experiments (four GC > AT and two GC > TA). In the control cultures, base substitutions in the coding and splicing regions were identified at 20 sites, eight of which were AT bp. In published data on hprt mutation in untreated T-cells in vivo and in vitro, 31 of 88 base substitutions have been reported to occur at AT bp. These results indicate that SO-induced mutations at the hprt locus in human T-lymphocytes are predominantly base substitutions, and suggest that in addition to DNA adducts at guanine bases, adducts at A and/or T bases also deserve attention with regard to the mutagenesis of SO.

Epoxy Compounds↗
PubMed2004

Analysis of networks based on styrene and divinylbenzene containing iron anchored using variable pressure scanning electron microscopy.

There is great demand for the development of composite materials containing small metal or metal oxides particles, owing to their variable properties and wide application. However, microscopic evaluation of these materials using high-vacuum scanning electron microscopy is difficult because the samples must undergo a series of preparation steps to reach a high image quality and to avoid becoming shrunk inside the microscope vacuum chamber. Thus, in this study, we used variable pressure scanning electron microscopy to evaluate the morphology and iron distribution on the surface of magnetic microspheres based on poly(styrene-co-divinylbenzene). These materials were obtained by suspension copolymerization of styrene and divinylbenzene in the presence of fine iron particles. Energy-dispersive X-rays were also used to analyse distribution of the iron particles. The results indicate that, under the conditions used, magnetic microspheres with a relatively narrow size distribution were formed. Moreover, the micrographs show that agglomerated iron particles appeared only on the microsphere surface.

Journal Article↗
PubMed1998

Helical superstructures from charged Poly(styrene)-Poly(isocyanodipeptide) block copolymers

Amphiphilic block copolymers containing a poly(styrene) tail and a charged helical poly(isocyanide) headgroup derived from isocyano-L-alanine-L-alanine and isocyano-L-alanine-L-histidine were prepared. Analogous to low-molecular mass surfactants, these block copolymers self-assembled in aqueous systems to form micelles, vesicles, and bilayer aggregates. The morphology of these aggregates can be controlled by variation of the length of the poly(isocyanide) block, the pH, and the anion-headgroup interactions. The chirality of the macromolecules results in the formation of helical superstructures that have a helical sense opposite to that of the constituent block copolymers. The great variety of morphologies displayed by these block copolymers and the fact that they are easily accessible from poly(styrene) and different types of peptides open new opportunities for applications in the fields of life and materials sciences.

Journal Article↗
PubMed1999

Engineering of a stable whole-cell biocatalyst capable of (S)-styrene oxide formation for continuous two-liquid-phase applications.

Recombinant strains of Pseudomonas putida KT2440 carrying genetic expression cassettes with xylene oxygenase- and styrene monooxygenase-encoding genes on their chromosomes could be induced in shaking-flask experiments to specific activities that rivaled those of multicopy-plasmid-based Escherichia coli recombinants. Such strains maintained the introduced styrene oxidation activity in continuous two-liquid-phase cultures for at least 100 generations, although at a lower level than in the shaking-flask experiments. The data suggest that placement of target genes on the chromosome might be a suitable route for the construction of segregationally stable and highly active whole-cell biocatalysts.

Bacteriological Techniques↗
PubMed1996

Biological activity of maleic anhydride copolymers. I. Biocompatibility and antitumoural effects of maleic anhydride-vinyl acetate, maleic anhydride-methyl methacrylate and maleic anhydride-styrene copolymers.

A series of maleic anhydride (MA)-vinyl acetate (VA), MA-methyl methacrylate (MM), and MA-styrene (S) copolymers were prepared and characterized. On employing various amounts of initiator, maleic anhydride-vinyl acetate, methyl methacrylate, and styrene copolymers with molecular weights ranging between 18,000 and 200,000 have been obtained. The in vivo and in vitro tests performed on K562 cellular cultures (human chronic myeloid leukemia) have shown that, as a function of the molecular weight, the synthesized copolymers demonstrate a 50% in vitro cytotoxicity and an average tumour regression of maximum 68%.

Animals↗
PubMed1999

Cibacron blue F3G-A-attached uniform and macroporous poly(styrene-co-divinylbenzene) particles for specific albumin adsorption.

Cibacron blue F3G-A-carrying uniform macroporous particles were proposed as an alternative sorbent for specific albumin adsorption. These particles were produced by a multistep polymerization procedure. In the first step of production, the uniform polystyrene seed particles were prepared by a dispersion polymerization method. Next. the polystyrene seed particles were first swollen by dibutylphthalate and then by styrene-divinylbenzene mixture in an aqueous emulsion medium. In the last step (i.e. repolymerization), styrene-divinylbenzene mixture was copolymerized within the swollen seed particles in the absence or presence of a stabilizer (e.g. poly(vinyl alcohol)). Although a considerable amount of non-specific BSA adsorption was observed on the surface of the particles produced in the absence of PVA, zero non-specific albumin adsorption could be achieved with the uniform macroporous particles produced in the presence of PVA. The stabilizer on the particle surface was also used as a ligand in the further derivatization of macroporous particles for specific albumin adsorption. Cibacron blue F3G-A was then covalently attached onto the surface of uniform macroporous particles. Specific albumin adsorption capacities up to 93 mg g(-1) could be achieved with the cibacron blue F3G-A-carrying macroporous particles of 6.25 microm in size.

Adsorption↗
PubMed2006

Synthesis of SiO2-coated Bi2S3/poly(styrene) nanocomposites by in-situ polymerization.

New nanocomposites containing silica-coated Bi2S3 nanofibers were synthesised by in situ polymerization using two distinct synthetic strategies: emulsion and suspension polymerization. Transmission and scanning electron microscopy of the nanocomposite particles showed that in both cases the Bi2S3/SiO2 nanoparticles were densely coated with poly(styrene). In situ emulsion polymerization afforded nanocomposites in which the nanofibers were coated with polymer spheres whilst suspension polymerization gives rise to a homogeneous polymer layer coat. The morphology of the poly(styrene) coating observed is discussed considering the surface modification of the nanofibers and the polymerization technique involved.

Bismuth↗
PubMed1987

Detoxification of styrene oxide by human liver glutathione transferase.

Cytosolic glutathione transferase (GST) was investigated in four human livers. The profile of GST activity was determined by isoelectric focusing using 1-chloro-2,4-dinitrobenzene as the electrophilic substrate. Three livers contained at least one basic and a near-neutral isoenzyme (GST mu). GST mu was not detectable in the fourth liver. The kinetics of GST with styrene oxide as the electrophilic substrate were studied in the cytosolic fraction, with the pooled fractions from isoelectric focusing containing high activity of GST mu transferase, and with GST mu purified to homogeneity. The cytosol obeyed Michaelis-Menten kinetics when styrene oxide was used as the variable substrate. The average (+/- s.e.m.) of the Vmax and Km were 21.9 +/- 7.9 nmol min-1mg-1 and 4.9 +/- 0.4 mM, respectively. At varying concentrations of glutathione, the enzyme did not obey Michaelis-Menten kinetics. Such kinetics were also observed with the fractions from isoelectric focusing and with the homogeneous GST mu fraction. The Eadie-Hofstee plot showed two phases: one with a low and another with a high Km value. The apparent Km values for the cytosol were 0.035 +/- 0.022 and 0.88 +/- 0.36 mM. The kinetic pattern of purified GST mu is consistent with that found in the cytosol.

Adult↗
PubMed2005

Purification and characterization of a yeast carbonyl reductase for synthesis of optically active (R)-styrene oxide derivatives.

Optically active styrene oxide derivatives are versatile chiral building blocks. Stereoselective reduction of phenacyl halide to chiral 2-halo-1-phenylethanol is the key reaction of the most economical synthetic route. Rhodotorula glutinis var. dairenensis IFO415 was discovered on screening as a potent microorganism reducing a phenacyl halide to the (R)-form of the corresponding alcohol. An NADPH-dependent carbonyl reductase was purified to homogeneity through four steps from this strain. The relative molecular mass of the enzyme was estimated to be 40,000 on gel filtration and 30,000 on SDS-polyacrylamide gel electrophoresis. This enzyme reduced a broad range of carbonyl compounds in addition to phenacyl halides. Some properties of the enzyme and preparation of a chiral styrene oxide using the crude enzyme are reported herein.

Alcohol Oxidoreductases↗
PubMed2002

Styrene maleic acid neocarzinostatin treatment for hepatocellular carcinoma.

A variety of treatments have recently been introduced to improve the prognosis of hepatocellular carcinoma (HCC). These anticancer therapies include the oily carcinostatic agent styrene maleic acid neocarzinostatin (SMANCS). SMANCS is a chemical conjugate of a synthetic copolymer of styrene maleic acid (SMA) and the proteinaceous anti-cancer agent neocarzinostatin (NCS), which dissolves in organic solvents such as pyridine and acetone, and particularly in Lipiodol. NCS is a simple protein capable of inhibiting DNA synthesis and inducing DNA degradation. Lipiodol is an ethyl ester of iodinated poppy seed oil in which most of the unsaturated double bonds in oleic, linoleic and linolenic acid are almost completely iodinated. When a homogeneous suspension of SMANCS with Lipiodol (SMANCS/Lipiodol) is administered intra-arterially, Lipiodol acts as a carrier of SMANCS. Many studies have demonstrated the clinical efficacy of SMANCS/Lipiodol in the treatment of HCC. We have shown that transcatheter arterial infusion (TAI) with SMANCS/Lipiodol has a more favorable focal therapeutic effect than does epirubicin in Lipiodol in the initial treatment of HCC. However, recent clinical studies have indicated that SMANCS causes severe adverse reactions and complications. We have also reported a case of HCC in which multifocal hepatic infarction developed after TAI with SMANCS/Lipiodol. Arterial administration of SMANCS/Lipiodol, therefore, should be given as peripherally as possible via the tumor feeding arteries, to enhance the efficacy of the agent and to reduce the adverse effects.

Animals↗
PubMedDate not supplied

Preparation and characterization of poly(styrene) microcapsules containing corrosion inhibitors.

A technique has been developed to view cross-sections of microcapsules prepared by a multiple emulsion method. Poly(styrene) microcapsules were prepared by emulsifying an aqueous solution containing sodium dichromate, a corrosion inhibitor, into an organic solution containing dissolved poly(styrene). This water-in-oil emulsion was added to an aqueous solution with stirring to form a water-in-oil-in-water emulsion. The organic solvent was removed under reduced pressure resulting in polystyrene walled microcapsules containing aqueous sodium dichromate. The microcapsules were embedded in an agarose gel and sliced for examination by transmission electron microscopy. The cross-sections clearly identified a core surrounded by a sponge-like polymeric wall. The microcapsules were also examined by scanning electron microscopy. These photomicrographs showed a smooth, continuous external wall structure.

Capsules↗
PubMed2003

Electrochromatographic properties of synthetic poly(styrene-divinylbenzene) encapsulated packing material and sulphonic cation-exchange phase based on the former.

OBJECTIVE: To develop new kinds of stationary phases suitable for applications in capillary electrochromatography (CEC), as well as in LC, which can be tailored to realize selective separations of solutes difficult to separate with conventional stationary phases. METHODS: Purchased spherical silica particles (5 microm) were refluxed in anhydrous toluene with vinyl-triethoxysilane for 18 h, to modify the surface with vinylsilyl groups. The silylated silica particles were subsequently stirred in an n-henanol-acetonitril mixture (1:4, volume fraction) for 18 h. Styrene and divinylbenzene in the mixture co-polymerized to form a crosslinked encapsulation layer on the silica surface, and bonded on the surface vinyl groups at the same time, both reactions were initiated by azo-iso-butyronitrile. The poly(Styrene-divinylbenzene) encapsulated silica(PS-DES) produced can be used as a non-conventional stationary phase for CEC itself. By sulphonation of the PS-DES phase with chlorosulphonic acid, strong cation-exchange stationary phase of sulphonic type was obtained. RESULTS: The manufactured PS-DES as well as the sulphonated phases were respectively packed into capillaries,and the columns thus prepared were tested for their chromatographic characteristics. It was found that the PS-DES phase showed reversed-phase characteristics. Due to the phenyl groups in the encapsulated polymer, it introduced pi-pi electronic interaction between the solutes molecules and stationary phase during the chromatographic separation process, therefore it showed unique selectivity on separating aromatic compounds, also polar- as well as some alkaline drugs was analyzed on the column packed with the phase. It was demonstrated that the sulphonated phase could be used to prepare columns for the separation of alkaline drugs, symmetric peaks were obtained for them and base-line separation was realized. CONCLUSION: It is possible that these stationary phases prepared can be used for solving the analytical problems in which non-conventional selectivity are needed ( the analyses of alkaline drugs are examples) In some cases, the analysts can realize the anticipated separation results based on the different separation mechanism from that of the conventional stationary phases.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

[Neurotoxic effect of 7,8-oxide styrene on striatal neuron culture].

The present study was undertaken to test the hypothesis that the neurotoxic action of styrene may be primarily presynaptic in nature and may involve impaired regulation of DA content and stimulation of DA release. Primary striatal neurons were grown in vitro and exposed to styrene oxide at different concentrations to evaluate the minimal effective dose able to induce these synaptic alterations.

Animals↗
PubMed1990

Antigen-binding activity of antibodies immobilized on styrene copolymer beads.

An important element of the Kodak thin-film immunoassay is antibody immobilized on small polymer beads. Monodisperse styrene copolymer beads offer a well-defined, high surface area substrate for covalent immobilization of monoclonal antibodies. The authors have used the ability of an immobilized monoclonal antibody directed against phenobarbitol, Phe 1.9, to recognize an antigen-enzyme conjugate to determine the extent of antibody activity retention and find that the packing density of antibody at the surface and the copolymer composition are important variables. For polystyrene homopolymer and some copolymers, antibody retention is greater as the packing density at the surface increases. Small changes in the copolymer composition, such as addition of 1% acrylamide or 10% acrylic acid, significantly increase the retention of binding activity of the antibody. The chemistry for covalent coupling of the antibody to the surface is also important. Phe 1.9 coupled to chloromethyl styrene copolymer beads retains less activity than when coupled to vinyl sulfone copolymer beads. Monodisperse sytrene copolymer beads provide great flexibility in the design of rapid immunoassays since a copolymer bead can be tailored to the specific requirements of the antibody and the analyte.

Antigen-Antibody Reactions↗