No abstract

As Alzheimer's disease pathogenesis is associated with the formation of insoluble aggregates of amyloid beta-peptide, approaches allowing the direct, noninvasive visualization of plaque growth in vivo would be beneficial for biomedical research. Here we describe the synthesis and characterization of the near-infrared fluorescence oxazine dye AOI987, which readily penetrates the intact blood-brain barrier and binds to amyloid plaques. Using near-infrared fluorescence imaging, we demonstrated specific interaction of AOI987 with amyloid plaques in APP23 transgenic mice in vivo, as confirmed by postmortem analysis of brain slices. Quantitative analysis revealed increasing fluorescence signal intensity with increasing plaque load of the animals, and significant binding of AOI987 was observed for APP23 transgenic mice aged 9 months and older. Thus, AOI987 is an attractive probe to noninvasively monitor disease progression in animal models of Alzheimer disease and to evaluate effects of potential Alzheimer disease drugs on the plaque load.

No abstract

How do retaining glycosyltransferases function? To answer this question, UDP‐Gal and galactose were covalently linked to form disubstrate analogues 1, of which surprisingly 1β and not 1α inhibited α(1‐3)‐galactosyltransferases very well. An understanding of this inhibition is a key to the pharmacological prevention of hyperacute rejection in pig to primate xenotransplantation.

Preformed and elicited Ab’s against the Galα1,3Gal terminating carbohydrate chains (αGal Ab’s) are the primary cause of hyperacute and acute vascular xenograft rejection in pig-to-primate transplantation. αGal Ab’s are produced by long-lived Ab-producing cells that are not susceptible to pharmacological immunosuppression. We reasoned that antigen-specific elimination of αGal Ab’s might be achieved in vivo by systemic administration of nonimmunogenic polyvalent αGal structures with high avidity for αGal Ab’s. We devised GAS914, a soluble trisaccharide-polylysine conjugate of approximately 500 kDa that effectively competes for αGal binding by αGal IgM (IC50, 43 nM) and IgG (IC50, 28 nM) in vitro. Injections of GAS914 in cynomolgus monkeys, at the dose of 1 mg/kg, resulted in the immediate decrease of more than 90% of circulating αGal Ab’s and serum anti-pig cytotoxicity. In baboons, repeated injections of GAS914 effectively reduced both circulating αGal Ab’s and cytotoxicity over several months. Studies with [14C]GAS914 in rhesus monkeys and Gal–/– mice indicate that GAS914 binds to circulating αGal Ab’s and that the complex is quickly metabolized by the liver and excreted by the kidney. Remarkably, posttreatment αGal Ab titers never exceeded pretreatment levels and no sensitization to either αGal or the polylysine backbone has been observed. Furthermore there was no apparent acute or chronic toxicity associated with GAS914 treatment in primates. We conclude that GAS914 may be used therapeutically for the specific removal of αGal Ab’s