Photolytic Measurement of Tissue S-Nitrosothiols in Rats and Humans In Vivo

S-nitrosothiols are labile thiol-NO adducts formed in vivo primarily by metalloproteins such as NO synthase, ceruloplasmin, and hemoglobin. Abnormal S-nitrosothiol synthesis and catabolism contribute to many diseases, ranging from asthma to septic shock. Current methods for quantifying S-nitrosothiols in vivo are suboptimal. Samples need to be removed from the body for analysis, and the S-nitrosothiols can be broken down during ex vivo processing. Here, we have developed a noninvasive device to measure mammalian tissue S-nitrosothiols in situ non-invasively using ultraviolet (UV) light, which causes NO release in proportion to the S-nitrosothiol concentration. We validated the assay in vitro; then, we applied it to measure S-nitrosothiols in vivo in rats and in humans. The method was sensitive to 0.5 µM, specific (did not detect other nitrogen oxides), and was reproducible in rats and in humans. This noninvasive approach to S-nitrosothiol measurements may be applicable for use in human diseases.

Nucleobase Protection of Deoxyribo- and Ribonucleosides

Oligonucleotides carrying a variety of chemical modifications including conjugates are finding increasing applications in therapeutics, diagnostics, functional genomics, proteomics, and as research tools in chemical and molecular biology. The successful synthesis of oligonucleotides primarily depends on the use of appropriately protected nucleoside building blocks including the exocyclic amino groups of the nucleobases, the hydroxyl groups at the 2'-, 3'-, and 5'-positions of the sugar moieties, and the internucleotide phospho-linkage. This unit is a thoroughly revised update of the previously published version and describes the recent development of various protecting groups that facilitate reliable oligonucleotide synthesis. In addition, various protecting groups for the imide/lactam function of thymine/uracil and guanine, respectively, are described to prevent irreversible nucleobase modifications that may occur in the presence of reagents used in oligonucleotide synthesis. © 2017 by John Wiley & Sons, Inc.