Trigeminal nerve - artery contact in people without trigeminal neuralgia - MR study.

BACKGROUND: Neurovascular conflict is regarded as the most common cause of idiopathic trigeminal neuralgia. It is suspected that a blood vessel in contact with the root entry zone of a trigeminal nerve causes its irritation. The aim of the study was to evaluate how signs of neurovascular conflict can be found in people without trigeminal neuralgia MATERIAL/METHODS: The study was conducted retrospectively. The authors analyzed MR examinations of 60 patients (120 nerves), aged 22-77 years, who did not have trigeminal neuralgia or related symptoms. Nerve-artery contact at the root entry zone of a trigeminal nerve, nerve deformation, and atrophy were searched for in angio-3D-TOF images (slice thickness: 1 mm). RESULTS: Contact between a trigeminal nerve and an artery was found in 30 cases (25% of nerves). The blood vessel was parallel to the nerve root in 14 cases (11.7%) and crossed it at a right or acute angle in 15 cases (12.5%). Contact between artery and atrophic nerve was found in one case. Modeling of the trigeminal nerve by an artery was not found. CONCLUSIONS: Contact between a trigeminal nerve root and an artery in the prepontine cistern is a frequently seen anatomical variant. Therefore, detection of such a variant is not equivalent to finding the cause of a patient's complaints.

[Molecular basis of ion selectivity based on crystalline structure of bacterial channels]. / Molekularne podloe selektywnosci na podstawie struktur krystalicznych kanalów bakteryjnych.

UNLABELLED: The principles of ionic selectivity of the two crystallised bacterial ion channels are described. These channels are: the potassium channel KcsA, whose amino-acid sequence is homologous to the eukaryotic voltage--dependent potassium channels and the chloride channel EcClC that is a prokaryotic member of the ClC family of chloride channels. IN CONCLUSION: although the overall molecular architecture of KcsA is different from that of EcClC, the selectivity filters in both cases show similarities. They both utilise helix dipoles organised within the channel molecule in such a fashion to produce electrostatically favourable environment for anions (in the case of EcClC) or cations (in the case of KcsA).