Poly with glass beads

New polymeric solid supports have been devised, which include macroporous styrene-divinylbenzene containing large fixed pores, porous glass beads, insoluble carbohydrate polymers, poly(ethylene oxide), cross-linked derivatives of polyacrylamide resins, and graft copolymers of polystyrene and poly(ethylene oxide). The last two have been the most effective and widely used and have competed well with the original copoly(styrene-divi-nylbenzene) beads. 

Several polymers were evaluated in the form of a surface coating on glass beads packed in columns to determine their ability to retain platelets when whole human blood passes over the surface. This ability was measured as the platelet retention index p, the fraction of platelets retained on the column. Lowest values of p were found for poly(ethylene oxide), polypropylene oxide), poly(tetramethylene oxide) (in the form of polyurethanes), and polydimethylsiloxane. Highest values (around 0.8) were found for cross-linked poly(vinyl alcohol) and the copolymers of ethylenediamine with diisocyanates. Intermediate values were found for polystyrene and its copolymers with methyl acrylate, for polyacrylate, and for poly(methyl methacrylate). The results are interpreted in terms of possible hydrophobic and hydrogen bonding interactions with plasma proteins. 

One g of the polymer-coated glass beads were closely packed in a tubing of poly(vinyl chloride) (i.d. - 3 mm) equipped with a stopcock, and the packed column was primed with physiological saline for 24 h to exclude a liquid-air interface and to equilibrate the polymer surface with the physiological environment. 

The formation of fibrils in poly(carbonate) (PC)/LCP blends have been shown to be enhanced by tbe addition of glass beads. Nano silica acts in the same way. For example, in PC/LCP blends the addition of nano silica results in a reduction of the viscosity. The reduction of viscosity is correlated with the fibrillation of tbe LCP which is promoted by nano silica. In blends of LCP and poly(sulfone) the addition of ca. 5% of nano silica effects the formation of long and perfectly orientated fibrils in the capillary flow. The nano silica forms a network in the matrix that increases the elasticity. This effect is responsible for the improvement of the formation of fibrils. 

Finally, the styrene-divinylbenzene copolymer is certainly not the only starting material suitable for functionalization. Impermeable polymers were grafted and porous glass beads coated with organic polymers for derivatization, but these pioneering efforts had few followers so far. More auspicious seems to be, at this time, the application of polyamides, such as polyacrylamide, poly-dimethylacrylamide or polydimethylacrylamide-co-Boc-j -alanylacroyl-hexa-methylenediamine. Their promise stems from the compatibiUty of the support with the peptide chain. 

Amphibole (crocidol-ite and amosite), serpentine (chrysotile), wollastonite, riebeglass beads Human and rabbit mesothelial cells in vitro Oligonucleosomal DNA fragmentation, loss of membrane phospholipid asymmetry, and nuclear condensation Asbestos fibres, not control particles, induced apoptosis in mesothelial cells by all assays. Induction of apoptosis was dose-dependent for all types of asbestos, with crocidolite (5 ng/cm ) inducing 15.0 1.1 % apoptosis versus control particles <4 %. Apoptosis induced by asbestos, but not by actinomycin D, was inhibited by extracellular catalase, superoxide dismutase in the presence of catalase, hypoxia (8 % oxygen), deferoxamine, 3-aminobenzamide [an inhibitor of poly(ADP-ribosyl) polymerase], and cytochalasin B. Only catalase and cytocha-lasin B decreased fibre uptake. Broaddus et al. (1996) Escape from asbestos-induced apoptosis could allow the abnormal survival of mesothelial cells with asbestos-induced mutations... 

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