Diffusion Tensor Imaging in Very Preterm, Moderate-Late Preterm and Term-Born Neonates: A Systematic Review.

OBJECTIVE: To examine white matter abnormalities, measured by diffusion tensor imaging, in very preterm (<32 weeks) and moderate-late preterm neonates (32-37 weeks) at term-equivalent age, compared with healthy full-term controls (≥37 weeks). STUDY DESIGN: A search of Medline (PubMed) was conducted to identify studies with diffusion data collected on very preterm, moderate-late preterm and full-term neonates, using the guidelines from the Meta-analysis of Observational Studies in Epidemiology and PRISMA statements. RESULTS: Eleven studies were included with diffusion tensor imaging data from 554 very preterm, 575 moderate-late preterm, and 318 full-term neonates. Widespread statistically significant diffusion measures were found in all preterm subgroups at term-equivalent age compared with full-term neonates, and this difference was more marked for the very preterm group. These abnormalities are suggestive of changes in the white matter microstructure in the preterm groups. The corpus callosum was a region of interest in both early and moderate-late preterm groups, which showed statistically significant diffusion measures in all 11 studies. CONCLUSIONS: Microstructural white matter changes may underpin the increased risk of neurodevelopmental disability seen in preterm infants in later life. diffusion tensor imaging may therefore be a useful prognostic tool for neuro-disability in preterm neonates.

Gas-phase intramolecular cyclization of argentinated N-allylbenzamides.

The fragmentations of argentinated N-allylbenzamides have been exhaustively studied through collision-induced dissociation and through deuterium labeling. The intriguing elimination of AgOH is certified as the consequence of intramolecular cyclization between terminal olefin and carbonyl carbon following proton transfer to carbonyl oxygen, rather than simple enolization of amide. Linear free energy correlations and density functional theory (DFT) calculations were performed to understand the competitive relationship between AgOH loss and AgH loss, which results from the 1,2-elimination of α-hydrogen (to the amido nitrogen) with the silver.