Mechanical properties of natural rubber/grafted cellulose fibre composites

Mechanical properties of natural rubber/allyl acrylate and allyl methacrylate grafted cellulose fibre composites are presented. Stress/strain measurements and dynamic mechanical measurements indicate that the adhesion between grafted fibres and matrix is better than that in samples containing untreated cellulose fibres. This makes it possible to vary the composite properties by varying the fibre type and/or fibre amount.     

Direct mass spectrometric analysis of ozonides: application to unsaturated glycerophosphocholine lipids

The reaction of ozone with double bonds present in glycerophosphocholine lipids results in formation of ozonides that can be directly analyzed by mass spectrometry as either positive or negative molecular ion species generated by electrospray ionization. Polyunsaturated fatty acyl groups esterified to the phospholipid yielded a mixture of ozonide species with the maximum number of ozone molecules added equal to the total number of double bonds. Ozonide decomposition resulted in omega-aldehyde and omega-carboxylic acid products as revealed by ESI-MS. Collisional activation of the ozone adducts for mono- and polyunsaturated phospholipids gave rise to fragment ions indicative of the position of the double bonds in these molecules. The major decomposition pathway for either positive or negative ozonide ion species involved charge remote fragmentation of the ozonide initiated by homolytic cleavage of the peroxide bridge followed by rearrangement to form the omega-aldehyde and omega-carboxylate acyl species. The reaction of ozone with phospholipids containing polyunsaturated fatty acyl groups is a useful method to probe the position of double bonds by electrospray ionization mass spectrometry.     

Lipid prodrugs of phosphonoacids: greatly enhanced antiviral activity of 1-O-octadecyl-sn-glycero-3-phosphonoformate in HIV-1, HSV-1 and HCMV-infected cells, in vitro

Phosphonoformate (PFA) effectively inhibits viral polymerases but is relatively ineffective in virus-infected cells in tissue culture. A lipid prodrug of phosphonoformate was synthesized by coupling the phosphonate residue of phosphonoformate to the sn-3 hydroxyl of 1-O-octadecyl-sn-glycerol. This prodrug, 1-O-octadecyl-sn-glycero-3-phosphonoformate (ODG-PFA), was 93-fold more active than phosphonoformate in cells infected with the AD169 strain of cytomegalovirus (CMV), and 111-147-fold more active in cells infected with three human clinical isolates of CMV. The compound was also 44-fold more active in human immunodeficiency virus-1 (HIV-1) infected cells and 43-fold more active in cells infected with herpes simplex virus (HSV). Studies of the mechanisms of increased antiviral activity indicate that 1-O-octadecyl-sn-glycero-3-[14C]phosphonoformate is taken up more extensively than the free drug by the host MRC-5 human lung fibroblasts. Intracellular enzymes convert 1-O-octadecyl-sn-glycero-3-phosphonoformate to phosphonoformate. This conversion does not occur in the tissue culture medium containing fetal bovine serum (FBS) or in MRC-5-conditioned medium. In view of its greatly increased in vitro potency and selectivity, 1-O-octadecyl-sn-glycero-3-phosphonoformate may be useful in treating viral diseases.     

Effects of fibroblasts on the growth of erythroid progenitor cells in vitro

The effect of embryo fibroblasts on the growth of erythroid colony-forming cells in vitro (CFU-e) from mouse bone marrow was investigated. First, the maintenance of CFU-e number in suspension culture was assayed. CFU-e recovered from suspension culture fell rapidly to values below 30% of the initial number. When erythropoietin (EP) was added, the initial decline during the first day was followed by a rise to 80%. In cultures supplemented with irradiated fibroblasts, the number of CFU-e did not show an abortive fall, but there was a slight increase during 3 days of culturing. The influence of fibroblasts on the colony-forming ability of CFU-e was studied in a semisolid culture system composed of an agar underlayer and a methylcellulose overlayer. The number of erythroid colonies scored after 5 days of culture in the presence of different levels of EP was proportional to the number of added fibroblasts and the colony size (depending on the number of fibroblasts) increased to macroscopic dimensions. Fibroblasts alone, without EP, induced colony formation by CFU-e if added in concentrations of 1 X 10(5) or higher. EP was not detectable in medium conditioned by the fibroblasts. These data indicate that fibroblasts may stimulate erythroid colony formation (in the absence of EP) and enhance the colony-forming ability of CFU-e in the presence of EP. From these results, it is suggested that fibroblasts exert proliferation activating effects on CFU-e target cells.     

Autonomic responses to shock-associated words in a nonattended message: a failure to replicate

Names of cities were shock associated and then embedded in material presented to the nonattended channel in a dichotic listening and shadowing situation. Despite earlier claims of differential responding to city names in the absence of awareness, no such differential responding was found. A test for conditioning following the dichotic listening task found that the subjects had been conditioned. Postexperimental interviews found that the subjects were aware of the city-shock contingency and had expected to be shocked during the dichotic listening task. Comparisons are made with other studies of galvanic skin responses to unattended words.