Preparation and biological activities of a bivalent poly(ethylene glycol) hybrid containing an active site and its synergistic site of fibronectin

A bivalent poly(ethylene glycol) or PEG hybrid of fibronectin-related peptides was prepared. An active site peptide (RGD) and its synergistic site peptide (PHSRN) of fibronectin were conjugated with an amino acid-type PEG (aaPEG) to form PHSRN-aaPEG-RGD. A moderate spatial array between RGD and PHSRN in fibronectin may be required for synergic activity. The bivalent hybrid exhibited potent cell spreading activity and exhibited potent anti-metastatic activity in a model of experimental metastasis with B16-BL6 cells in mice. PEG may serve as a spacer for maintaining the desired spatial array.     

DNA改性聚砜多孔微球选择性清除环境激素

将DNA视为生物大分子材料,制成DNA改性聚砜微球,在生物体外考察改性微球对环境激素,包括重金属离子的选择性清除.制备了2种改性聚砜微球:DNA共混微球(将DNA共混入聚砜溶液,当混合溶液滴入水中时,发生相分离而沉淀)和DNA表面改性聚砜微球(先制备聚砜多孔微球,再通过紫外线照射的方法将DNA接枝到聚砜微球表面).两种DNA改性聚砜微球在水中比较稳定,在酸或碱性条件下,由于DNA水解而不稳定.对环境激素的清除结果表明,DNA改性聚砜微球可以选择性清除包括联苯、苯酚和二恶荚类环境荷尔蒙物质;同时选择性吸附锌、铜、银、铅和铬等重金属离子.     

Dependence of ortho-positronium pick-off annihilation lifetime on free volume in organic molecular liquids calculated by Kincaid Eyring method, and positronium bubble formation

Sizes of free volume were quantitatively calculated for 42 organic liquids by means of the Kincaid and Eyring method. The results were discussed in relation to the pick-off annihilation lifetime of ortho-positronium in molecular liquids. The presence of strong correlation was found between them, this fact made us conclude that the free volume size was the most essential physical parameter, which determines the pick-off annihilation rate of ortho-positronium. The problem that the calculated free volume was too small for the existence of ortho-positronium could be eliminated by the equilibristic formation of a bubble around ortho-positronium. Correlation was shown between the free volume radii and bubble radii. Our discussion will likely apply to a wider area for the analysis of empirical data on pick-off rate of ortho-positronium in organic liquids and to the experimental investigation of the pick-off process of ortho-positronium annihilation.     

Electron microscopy of submicron particles in natural waters—Detection of organic substances

Submicron particles, 0.1–1 m in diameter, in pond water were collected on a 10–20 nm thick carbon film mounted on a carbon coated nylon grid by centrifugation and exposed to osmium(VIII) oxide vapor at room temperature for 2 h. Organic substances reacted with the reagent, while alumino-silicates and hydrated iron(III) oxide as well as the carbon film did not. The X-ray image of osmium revealed that organic substances, presumably humic substances, were associated with most of the particles, especially with hydrated iron (III) oxide, in the pond water.