Assembly of Tight Junction Strands: Claudin-10b and Claudin-3 Form Homo-Tetrameric Building Blocks that Polymerise in a Channel-Independent Manner.

Tight junctions regulate paracellular permeability size and charge selectively. Models have been proposed for the molecular architecture of tight junction strands and paracellular channels. However, they are not fully consistent with experimental and structural data. Here, we analysed the architecture of claudin-based tight junction strands and channels by cellular reconstitution of strands, structure-guided mutagenesis, in silico protein docking and oligomer modelling. Prototypic channel- (Cldn10b) and barrier-forming (Cldn3) claudins were analysed. Förster resonance energy transfer (FRET) assays indicated multistep claudin polymerisation, starting with cis-oligomerization specific to the claudin subtype, followed by trans-interaction-triggered cis-polymerisation. Alternative protomer interfaces were modelled in silico and tested by cysteine-mediated crosslinking, confocal- and freeze fracture EM-based analysis of strand formation. The analysed claudin mutants included also mutations causing the HELIX syndrome. The results indicated that protomers in Cldn10b and Cldn3 strands form similar antiparallel double rows, as has been suggested for Cldn15. Mutually stabilising -hydrophilic and hydrophobic - cis- and trans-interfaces were identified that contained novel key residues of extracellular segments ECS1 and ECS2. Hydrophobic clustering of the flexible ECS1 ß1ß2 loops together with ECS2-ECS2 trans-interaction is suggested to be the driving force for conjunction of tetrameric building blocks into claudin polymers. Cldn10b and Cldn3 are indicated to share this polymerisation mechanism. However, in the paracellular centre of tetramers, electrostatic repulsion may lead to formation of pores (Cldn10b) and electrostatic attraction to barriers (Cldn3). Combining in vitro data and in silico modelling, this study improves mechanistic understanding of paracellular permeability regulation by elucidating claudin assembly and its pathologic alteration as in HELIX syndrome.

[Are we controlling the sedation in ICU? A multicenter study results].

The aim of this study is to evaluate the issues of sedation and analgesia in all-purpose ICUs in Russia. To obtain that, a single-day observational survey was performed in 55 ICUs of Ural and Siberia regions. This work enabled to describe the targets, instruments of control and patterns of sedative and analgetics and sedatives prescription, as well as to make conclusions about issues in this area and possibilities of creation and necessity of analgesia and sedation standards. The study has shown a decent percentage of use of standardized scales evaluating pain in ICU and predominance of effectivae drugs and analgesia patterns, which leads to "formalization" of analgesia and decrease of it's effectiveness. Sedation indications do not satisfy the modern concept, sedation level evaluation scores are used only in 13%, schemes and drugs are traditional. The results of this study may serve as a reason for discussion of necessity of introducing of sedative and analgetic therapy in ICU standarts.

[Minor congenital ear malformations: surgical management and results]. / Wyniki leczenia operacyjnego malych wad rozwojowych ucha srodkowego.

The study present the results of surgical treatment of minor congenital anomalies of the middle ear in children. The ossiculoplastic procedures and the different types of stapedectomy carried out in the Department of Otolaryngology of Institute of the "Polish Mother's Hospital" in Lódz on 18 patients (11 girls and 7 boys) aged 5-16 years, with minor congenital anomalies of the middle ear. One month after the surgical procedure a lasting hearing improvement averaging 21.69 +/- 10.00 dB and 6 month after operation hearing improvement 21.91 +/- 9.75 dB was gained. The results of surgical procedures in minor congenital anomalies of the middle ear are not so good as in otosclerosis.

[Rhabdomyosarcoma of the middle ear in childhood]. / Rhabdomyosarcoma ucha srodkowego u dzieci.

The authors have described a case of a 2.5-year-old boy who suffered from rhabdomyosarcoma of the middle ear. The clinical course, differential histopathology diagnosis and dynamic growth of the tumor have also been presented. In spite of combined therapy--surgery and chemotherapy--prognosis in rhabdomyosarcoma of the middle ear in childhood is poor.