The surface of vascular endothelium bears a glycocalyx comprised, in part, of a complex mixture of oligosaccharide chains attached to cell-surface proteins and membrane lipids. Importantly, understanding of the structure and function of the endothelial glycocalyx is poorly understood. Preliminary studies have demonstrated structural differences in the glycocalyx of pulmonary artery endothelial cells compared with pulmonary microvascular endothelial cells. Herein we begin to probe in more detail structural and functional attributes of endothelial cell-surface carbohydrates. In this study we focus on the expression and function of sialic acids in pulmonary endothelium. We observed that, although pulmonary microvascular endothelial cells express similar amounts of total sialic acids as pulmonary artery endothelial cells, the nature of the sialic acid linkages differs between the two cell types such that pulmonary artery endothelial cells express both α( 2 , 3 )- and α( 2 , 6 )-linked sialic acids on the surface (i.e., surficially), whereas microvascular endothelial cells principally express α( 2 , 3 )-linked sialic acids. To determine whether sialic acids play a role in endothelial barrier function, cells were treated with neuraminidases to hydrolyze sialic acid moieties. Disruption of cell-cell and cell-matrix adhesions was observed following neuraminidase treatment, suggesting that terminal sialic acids promote endothelial barrier integrity. When we measured transendothelial resistance, differential responses of pulmonary artery and microvascular endothelial cells to neuraminidase from Clostridium perfringens suggest that the molecular architecture of the sialic acid glycomes differs between these two cell types. Collectively our observations reveal critical structural and functional differences of terminally linked sialic acids on the pulmonary endothelium.

Abstract-Store-operated calcium (SOC) entry is sufficient to disrupt the extra-alveolar, but not the alveolar, endothelial cell barrier.

Recently, we carried out a density functional theory B3LYP/6-31+G(d) study of hexamethylene triperoxide diamine (HMTD) in order to elucidate the unusual, nearly planar, sp 2 hybridization of the two bridgehead nitrogen atoms, each bonded to the three CH 2 groups. We postulated that extended bonding orbitals between peroxide oxygens results in charge delocalization which decreases lone-pair repulsion and compensates the energy loss due to the sp 3 to sp 2 hybridization change on the nitrogen atoms. We have reexamined the crystal structure of HMTD by performing low-temperature, single-crystal X-ray studies, and we have determined that the unit cell contains a 50-50 racemic mixture of enantiomeric forms of HMTD, showing disorder about the mirror plane. At the low temperature, all hydrogen atoms were located and resolved, which was not previously possible. We have also crystallized and performed low-temperature X-ray analysis of a never previously reported dialdehyde form of HMTD, tetramethylene diperoxide diamine dialdehyde (TMDDD), which reveals enantiomers present in the unit cell without disorder. B3LYP density functional theory studies of HMTD and TMDDD are presented, as well as a transition state investigation of possible thermal interconversion of the HMTD enantiomers.

Hexamethylene triperoxide diamine (HMTD) is a powerful initiating explosive belonging to the family of triperoxide energetic materials. Single-crystal X-ray studies of this compound have revealed exactly planar 3-fold coordination about the two bridgehead nitrogen atoms. We have performed density functional theory B3LYP/6-31+G(d) calculations of HMTD to study the electronic nature of this very unusual coordination and to analyze the energetics and structure of this high-energy compound. The calculated geometry of HMTD was found to agree very well with the X-ray data. The vibrational spectrum of this molecule was also calculated and favorably compared to a diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) singlecrystal spectrum.

Morrow KA, Seifert R, Kaever V, Britain AL, Sayner SL, Ochoa CD, Cioffi EA, Frank DW, Rich TC, Stevens T. Heterogeneity of pulmonary endothelial cyclic nucleotide response to Pseudomonas aeruginosa ExoY infection.

Readily prepared imidazole-based boronium ions form stable, hydrophobic, room-temperature ionic liquids (RTIL) with unique electronic and spectroscopic characteristics.

No abstract

No abstract