Development of a highly sensitive method for the quantitative analysis of modified nucleosides using UHPLC-UniSpray-MS/MS.

There are more than 150 types of naturally occurring modified nucleosides, which are believed to be involved in various biological processes. Recently, an ultrahigh performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UHPLC-ESI-MS/MS) technique has been developed to measure low levels of modified nucleosides. A comprehensive analysis of modified nucleosides will lead to a better understanding of intracellular ribonucleic acid modification, but this analysis requires high-sensitivity measurements. In this perspective, we established a highly sensitive and quantitative method using the newly developed ion source, UniSpray. A mass spectrometer was used with a UniSpray source in positive ion mode. Our UHPLC-UniSpray-MS/MS methodology separated and detected the four major nucleosides, 42 modified nucleosides, and dG15N5 (internal standard) in 15 min. The UniSpray method provided good correlation coefficients (>0.99) for all analyzed nucleosides, and a wide range of linearity for 35 of the 46 nucleosides. Additionally, the accuracy and precision values satisfied the criteria of <15% for higher concentrations and <20% for the lowest concentrations of all nucleosides. We also investigated whether this method could measure nucleosides in biological samples using mouse tissues and non-small cell lung cancer clinical specimens. We were able to detect 43 and 31 different modified nucleosides from mouse and clinical tissues, respectively. We also found significant differences in the levels of N6-methyl-N6-threonylcarbamoyladenosine (m6t6A), 1-methylinosine (m1I), 2'-O-methylcytidine (Cm), 5-carbamoylmethyluridine (ncm5U), 5-methoxycarbonylmethyl-2-thiouridine (mcm5S2U), and 5-methoxycarbonylmethyl-2'-O-methyluridine (mcm5Um) between cancerous and noncancerous tissues. In conclusion, we developed a highly sensitive methodology using UHPLC-UniSpray-MS/MS to simultaneously detect and quantify modified nucleosides, which can be used for analysis of biological samples.

A Novel alphavbeta3 integrin antagonist suppresses neointima formation for more than 4 weeks after balloon injury in rats.

OBJECTIVES: We performed a detailed kinetic analysis in a rat balloon injury model to clarify the essential roles of alphavbeta3 integrin and endothelial cell (EC) regeneration in neointima formation. Using this model, we evaluated the antistenotic effect of Dainippon compound BS-1417, a novel alphavbeta3 integrin antagonist. METHODS AND RESULTS: Kinetic analysis using RT-PCR showed that alphavbeta3 integrin-related genes are upregulated before neointima formation. Morphological and functional analyses revealed that EC regeneration requires >4 weeks after injury, and that recovery of EC normal function coincides with the arrest of neointima formation. Subcutaneous infusion of BS-1417 for 2, 4, 7, or 12 weeks after injury potently inhibited neointima formation without affecting EC regeneration. Although withdrawal of treatment with BS-1417 after short-term administration after injury resulted in catch-up growth of neointima, a long-term study suggested that this catch-up growth can be prevented by continuous administration of BS-1417 until EC regeneration. CONCLUSIONS: We clarified that alphavbeta3 integrin and EC regeneration play an essential role in neointima formation, and that continuous administration of BS-1417 potently and stably inhibits neointima formation without affecting EC regeneration. These findings suggest that BS-1417 might be useful as a novel systemic drug for the treatment of restenosis.

Discovery of a potent and selective alpha v beta 3 integrin antagonist with strong inhibitory activity against neointima formation in rat balloon injury model.

A new series of phenylpiperazine-based derivatives with strong antagonistic activity for alpha v beta 3 integrin were synthesized. Of these derivatives, the fluorine-substituted compound 8 showed strong inhibitory activity and high selectivity for alpha v beta 3 integrin receptor (IC(50) = 0.055 nM). In vivo evaluation of the antistenotic effects of 8 indicated that this compound significantly inhibits neointima formation in rat balloon injury model.