Mass spectrometric study of ring-substituted secondary and tertiary γ-aminopiperidines

Fragmentation of secondary and tertiary γ-aminopiperidines proceeds via elimination of γ-amino radicals and the ring substituents of piperidine, and is accompanied by their cleavage. High-resolution mass spectral data, DADI spectra, and fragmentation of deutero analogs confirm this decomposition. On the basis of quantum chemical MNDO calculations the most probable alternate structures have been proposed for a number of typical ions. From the features of dissociative ionization we can determine the kind and location of substituents in the piperidine ring. © 1990 Plenum Publishing Corporation

Mass spectrometric study of ring-substituted secondary and tertiary γ-aminopiperidines

Fragmentation of secondary and tertiary γ-aminopiperidines proceeds via elimination of γ-amino radicals and the ring substituents of piperidine, and is accompanied by their cleavage. High-resolution mass spectral data, DADI spectra, and fragmentation of deutero analogs confirm this decomposition. On the basis of quantum chemical MNDO calculations the most probable alternate structures have been proposed for a number of typical ions. From the features of dissociative ionization we can determine the kind and location of substituents in the piperidine ring. © 1990 Plenum Publishing Corporation

In vivo dynamics of acidosis and oxidative stress in the acute phase of an ischemic stroke in a rodent model.

Ischemic cerebral stroke is one of the leading causes of death and disability in humans. However, molecular processes underlying the development of this pathology remain poorly understood. There are major gaps in our understanding of metabolic changes that occur in the brain tissue during the early stages of ischemia and reperfusion. In particular, it is generally accepted that both ischemia (I) and reperfusion (R) generate reactive oxygen species (ROS) that cause oxidative stress which is one of the main drivers of the pathology, although ROS generation during I/R was never demonstrated in vivo due to the lack of suitable methods. In the present study, we record for the first time the dynamics of intracellular pH and H2O2 during I/R in cultured neurons and during experimental stroke in rats using the latest generation of genetically encoded biosensors SypHer3s and HyPer7. We detect a buildup of powerful acidosis in the brain tissue that overlaps with the ischemic core from the first seconds of pathogenesis. At the same time, no significant H2O2 generation was found in the acute phase of ischemia/reperfusion. HyPer7 oxidation in the brain was detected only 24 h later. Comparison of in vivo experiments with studies on cultured neurons under I/R demonstrates that the dynamics of metabolic processes in these models significantly differ, suggesting that a cell culture is a poor predictor of metabolic events in vivo