Tadalafil can be combined with rilpivirine without dose adjustment or drug monitoring in HIV patients with ED or PAH. Rilpivirine at daily therapeutic doses of 25 mg does not induce or inhibit CYP3A-dependent drug metabolism.
Hexafluorodianhydride–oxydianiline (HFDA–ODA) polyimide was characterized using x-ray photoelectron spectroscopy (XPS). Elemental composition and polymer stoichiometry as elucidated with XPS are reported. The HFDA–ODA polymer cured at 360 °C was fully imidized giving rise to a single nitrogen 1s peak at 400.8 eV. The carbon 1s data showed an unexpectedly large peak at 285.9 eV. This peak could not be justified only by C–N and C–O electrons, but required the carbon 1s electrons from the HFDA aromatic rings to be included. The small peak at 287.5 eV was assigned to the tertiary carbon 1s electrons of the –C(CF3)2 group. The carbon 1s data interpretation is substantiated by molecular orbital calculations.
Glycosaminoglycans (GAGs) are a class of heterogeneous, often highly sulfated glycans that form linear chains consisting of up to 100 monosaccharide building blocks and more. GAGs are ubiquitous constituents of connective tissue, cartilage, and the extracellular matrix, where they have key functions in many important biological processes. For their characterization by mass spectrometry (MS) and tandem MS, the high molecular weight polymers are usually enzymatically digested to oligomers with a low degree of polymerization (dp), typically disaccharides. However, owing to their lability elimination of sulfate groups upon desorption/ionization is often encountered leading to a loss of information on the analyte. Here, we demonstrate that, in particular, water ice constitutes an extremely mild matrix for the analysis of highly sulfated GAG disaccharides by infrared matrix-assisted laser desorption/ionization (IR-MALDI) mass spectrometry. Depending on the degree of sulfation, next to the singly charged ionic species doubly- and even triply charged ions are formed. An unambiguous assignment of the sulfation sites becomes possible by subjecting sodium adducts of the GAGs to low-energy collision-induced dissociation tandem MS. These ionic species exhibit a remarkable stability of the sulfate substituents, allowing the formation of fragment ions retaining their sulfation that arise from either cross-ring cleavages or rupture of the glycosidic bonds, thereby allowing an unambiguous assignment of the sulfation sites.
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