A Fluorescent Probe for Glycosaminoglycans Applied to the Detection of Dermatan Sulfate by a Mix-and-Read Assay

Glycosaminoglycans are complex biomolecules of great biological and medical importance. The quantification of glycosaminoglycans, in particular in complex matrices, is challenging due to their inherent structural heterogeneity. Heparin Red, a polycationic, fluorescent perylene diimide derivative, has recently emerged as a commercial probe for the convenient detection of heparins by a mix-and-read fluorescence assay. The probe also detects glycosaminoglycans with a lower negative charge density than heparin, although with lower sensitivity. We describe here the synthesis and characterization of a structurally related molecular probe with a higher positive charge of +10 (vs. +8 of Heparin Red). The superior performance of this probe is exemplified by the quantification of low dermatan sulfate concentrations in an aqueous matrix (quantification limit 1 ng/mL) and the detection of dermatan sulfate in blood plasma in a clinically relevant concentration range. The potential applications of this probe include monitoring the blood levels of dermatan sulfate after administration as an antithrombotic drug in the absence of heparin and other glycosaminoglycans.

[3,3]-Sigmatropic rearrangement step in the gold-catalyzed cyclization of allyl-(ortho-alkinylphenyl)methyl ethers

The gold-catalyzed conversion of allyl-(ortho-alkynylphenyl)methyl ethers was investigated, and allylated isochromenes were obtained. An optimization of the catalysis conditions with respect to different phosphane and carbene ligands on gold, different counterions, and different solvents was conducted. Subsequently, the scope and limitations of this reaction were investigated with 21 substrates. The mechanistic studies show an allylic inversion, as supported by NMR data and an X-ray crystal structure analysis, as well as an intermolecular reaction, as determined by crossover experiments. There is no competition of protodeauration even in the presence of water. All these observations differ from other related conversions and clearly indicate product formation by a [3,3]sigmatropic rearrangement in the step forming the new C-C bond.

Murine leukemia virus-induced neurodegeneration of rats: enhancement of neuropathogenicity correlates with enhanced viral tropism for macrophages, microglia, and brain vascular cells

A highly neuropathogenic retrovirus, NT40, was generated by serially passaging an infectious molecular clone of Friend murine leukemia virus, FB29, through F344 Fisher rats. NT40 induced severe neurological signs such as reflex abnormalities and ataxia within 4-6 weeks following neonatal inoculation. FB29 led to only very mild neurological dysfunctions with longer incubation periods. Pathological alterations were characterized by mild (FB29) to extensive (NT40) noninflammatory spongiform degeneration, mainly of brain-stem areas. Infectious center assays revealed that viral titers in brain tissues of NT40-infected rats were 100-fold higher than those of FB29-infected animals. Employing immunohistochemistry, in situ hybridization, and flow cytometry, NT40 was found to infect many endothelial cells of brain blood vessels and microglia, whereas FB29 infected only microglia and those to a lower extent. However, when isolated from adult diseased rats, microglial cells turned out in both cases to be nonproductively infected with either FB29 or NT40. Of peripheral organs, we found enhanced levels of NT40 in peritoneal macrophages but not in spleen, thymus, or serum when compared to FB29. Altogether these data suggest that an expanded cellular tropism within the CNS and elevated viral titers in macrophages and microglia correlated with enhancement of neuropathogenicity.