[Vertebrobasilar insufficiency caused by extravasal compression of the vertebral artery in the second segment].

Objective: To develop indications for surgical treatment for positional disorders of blood flow in the vertebral-basilar territory caused by the damage to the V2-V3 segment of the vertebral artery (VA).

Material And Methods: One hundred and fourteen patients with systemic and non-systemic dizziness were studied. To assess the state of the VA, blood circulation of the posterior cranial fossa and the base of the brain, ultrasound duplex scanning of blood vessels, selective angiography, MRI, single photon emission computed tomography (SPECT) of the brain and neuropsychological testing were performed.

Pyridine-Containing Donor-Acceptor Diarylnitroxides: Noncovalent Stabilization of the Redox States.

A series of new pyridyl- or 2-pyridyloxide-containing donor-acceptor diarylnitroxides was obtained and characterized; high stability of the ortho-2-pyridyl-containing diarylnitroxides was determined by kinetic measurements (τ =1733 h in benzene). Comparative voltammetric study of new nitroxides and their analog in which the Py replaces the Ph group revealed both through-bond and through-space stabilization of the NO redox states with the pyridyl/ 2-pyridyloxide moiety, providing reversibility of both oxidation and reduction processes. Adaptive conformational behavior of new pyridyl/pyridyloxide containing nitroxides upon one-electron oxidation and reduction was confirmed by DFT calculations.