␤ 2 -glycoprotein I ( ␤ 2 -GPI) is a major antigen for antiphospholipid antibodies (Abs, aPL) present in patients with antiphospholipid syndrome (APS). We recently reported ( J. Lipid Res ., 42: 697, 2001; J. Lipid Res. , 43: 1486, 2002) that ␤ 2 -GPI specifically binds to Cu 2 ؉ -oxidized LDL (oxLDL) and that the ␤ 2 -GPI ligands are -carboxylated 7-ketocholesteryl esters. In the present study, we demonstrate that oxLDL forms stable and nondissociable complexes with ␤ 2 -GPI in serum, and that high serum levels of the complexes are associated with arterial thrombosis in APS. A conjugated ketone function at the 7-position of cholesterol as well as the -carboxyl function of the ␤ 2 -GPI ligands was necessary for ␤ 2 -GPI binding. The ligand-mediated noncovalent interaction of ␤ 2 -GPI and oxLDL undergoes a temperature-and time-dependent conversion to much more stable but readily dissociable complexes in vitro at neutral pH. In contrast, stable and nondissociable ␤ 2 -GPI-oxLDL complexes were frequently detected in sera from patients with APS and/or systemic lupus erythematodes. Both the presence of ␤ 2 -GPI-oxLDL complexes and IgG Abs recognizing these complexes were strongly associated with arterial thrombosis. Further, these same Abs correlated with IgG immune complexes containing ␤ 2 -GPI or LDL. Thus, the ␤ 2 -GPI-oxLDL complexes acting as an autoantigen are closely associated with autoimmune-mediated atherogene-

Laminin, a major component of the basement membrane, has diverse biological activities. Recently, we identified various biologically active sequences on laminin-1 by using a large set of synthetic peptides. Chitosan, a polysaccharide, is biodegradable and has been used as a biomaterial. Here, we conjugated several biologically active laminin peptides onto chitosan membranes and measured the cell attachment activity of peptide-conjugated chitosan membranes with various cell types. The active laminin peptide-conjugated chitosan membranes promoted cell attachment with cell type specificity. A99 (AGTFALRGDNPQG)-chitosan membrane promoted cell attachment with well-organized actin stress fibers. This adhesion was inhibited by EDTA but not by heparin. AG73 (RKRLQVQLSIRT)-chitosan membrane promoted cell attachment with filopodia formation, and this adhesion was inhibited by heparin but not by EDTA. These data suggest that the A99-chitosan membrane interacted with an integrin cellular receptor and that the AG73-chitosan membrane promoted proteoglycan-mediated cell attachment, as previously reported. Furthermore, both AG73-chitosan and A99-chitosan membranes effectively promoted neurite outgrowth with PC12 rat pheochromocytoma cells. We conclude that conjugation on a chitosan membrane is applicable for testing quantitatively the biological activity of synthetic peptides and that these constructs have a potential ability to serve as bioadhesive materials for tissue regeneration and engineering.

Large amounts of DNA‐enriched materials, such as salmon milts and shellfish gonads, are discarded as industrial waste. We have been able to convert the discarded DNA to a useful material by preparing novel DNA films by UV irradiation. When DNA films were irradiated with UV light, the molecular weight of DNA was greatly increased. The reaction was inhibited by addition of the radical scavenger galvinoxyl suggesting that the DNA polymerization with UV irradiation proceeded by a radical reaction. Although this UV‐irradiated DNA film was water‐insoluble and resistant to hydrolysis by nuclease, the structure of the DNA film in water was similar to non‐irradiated DNA and maintained B‐form structure. In addition, the UV‐irradiated DNA film could effectively accumulate and condense harmful DNA‐intercalating compounds, such as ethidium bromide and acridine orange, from diluted aqueous solutions. The binding constant and exclusion number of ethidium bromide for UV‐irradiated DNA were determined to be 6.8±0.3×104 M−1 and 1.6±0.2, respectively; these values are consisted with reported results for non‐irradiated DNA. The UV‐irradiated DNA films have potential uses as a biomaterial filter for the removal of harmful DNA intercalating compounds.

␤ 2 -Glycoprotein I ( ␤ 2 -GPI) is a major antigen for anticardiolipin antibodies (aCL, Abs) present in patients with antiphospholipid syndrome. We recently reported that ␤ 2 -GPI specifically binds to oxidized LDL (oxLDL) and that the ␤ 2 -GPI's major ligand, oxLig-1 is 7-ketocholesteryl-9-carboxynonanoate (Kobayashi, K., E. Matsuura, Q. P.