SYD-1, a presynaptic protein with PDZ,C2 and rhoGAP-like domains,specifies axon identity in C. elegans

Axons are defined by the presence of presynaptic specializations at specific locations. We show here that loss-of-function mutations in the C. elegans gene syd-1 cause presynaptic specializations to form in the dendritic processes of GABA-expressing motor neurons during initial differentiation. At a later developmental stage, however, syd-1 is not required for the polarity respecification of a subset of these neurons. The SYD-1 protein contains PDZ, C2 and rho-GTPase activating protein (GAP)-like domains, and is localized to presynaptic terminals in mature neurons. A truncated SYD-1 that lacks the rhoGAP domain interferes with neurite outgrowth and guidance. Our data indicate that syd-1 may be involved in specifying axon identity during initial polarity acquisition.     

Number of active centers and propagation rate constants in the propene polymerization on supported Ti–Mg catalysts in the presence of hydrogen

Polymerization inhibition with radioactive carbon monoxide was used to determine the number of active centers (C_p) and the propagation rate constant (K_p) in the isospecific polymerization of propene with the catalytic system TiCl₄/diisobutyl phthalate/MgCl₂—AlEt₃—PhSi(OEt)₃. The presence of hydrogen was found to decrease C_p (by a factor of ≈ 2) and to increase k_p (by a factor of ≈ 4). In the absence of hydrogen a considerable part of the active centers (titanium-polymer bonds) reacting with ¹⁴CO seems to be inactive in the propene polymerization for steric reasons. Hydrogen is able to transform such centers into an active state. Thus, k_p ≈ 2,5 · 10³ L/(mol · s) at 70°C obtained in propene polymerization in the presence of the hydrogen seems to be correct, since the portion of centers in the active state is maximum. The influence of polymerization time, external and internal donors on C_p and k_p was studied.     

The combination of soluble IL-18Ralpha and IL-18Rbeta chains inhibits IL-18-induced IFN-gamma.

Although the beta chain of interleukin-18 receptor (IL-18Rbeta) is required for signaling, the soluble (extracellular) form does not bind IL-18, and its role in inhibiting IL-18 is unclear. In the present study, both the soluble human IL-18 ligand binding alpha chain (sIL-18Ralpha) and the sIL-18Rbeta chain were investigated for inhibition of IL-18-induced interferon-gamma (IFN-gamma) production in human peripheral blood mononuclear cells (PBMC), whole blood, and KG-1 macrophage and natural killer (NK) cell lines. Neutralization of IL-18 by soluble receptors was compared with that of the IL-18 binding protein (IL-18BP). An equimolar concentration IL-18BP inhibited 90% of IL-18 activity, whereas a 4-fold molar excess of sIL-18Ralpha had no effect. A dimeric construct of sIL-18Ralpha linked to the Fc domain of IgG1 (sIL-18Ralpha:Fc) increased IL-18 activity 2.5-fold. In PBMC stimulated with lypopolysaccharide (LPS) or in whole blood stimulated with Staphylococcus epidermidis, 3 nM IL-18BP reduced IFN-gamma by 80%, whereas IL-18Ralpha:Fc had no effect. A construct of the sIL-18Rbeta linked to Fc (sIL-18Rbeta:Fc) did not affect IL-18-induced IFN-gamma even at 80-fold molar excess of IL-18. However, the combination of both soluble receptors reduced IFN-gamma by 80%. In KG-1 cells, a 50% reduction in IL-18 activity was observed using an 80-fold molar excess of sIL-18Ralpha:Fc but only in the presence of sIL-18Rbeta:Fc. Similarly, a 50% reduction was observed using sIL-18Rbeta:Fc in the presence of a molar excess of sIL-18Ralpha:Fc. Similar inhibition was observed in NK cells. These studies reveal that the combination of the ligand-binding and the nonligand-binding extracellular domains of IL-18R is needed to inhibit IL-18, whereas IL-18BP neutralizes at equimolar concentration.     

Application of different kinds of internal biliary duct drainage in emergency surgery

The immediate and late results of treatment of 139 patients, operated on with formation of biliodigestive anastomosis, were analyzed. Six (4.32%) patients died. Of 39 patients, to whom choledochoduodenostomy was performed, in 18--good late follow-up result was noted and the fair one--in 21. Of 23 patients, in whom choledochojejunostomy in Roux-en-Y fashion was performed, good result was noted in 4, fair--in 18 and poor--in 1.     

Nanocrystalline SnO2 Functionalized with Ag(I) Organometallic Complexes as Materials for Low Temperature H2S Detection

This paper presents a comparative analysis of H₂S sensor properties of nanocrystalline SnO₂ modified with Ag nanoparticles (AgNPs) as reference sample or Ag organic complexes (AgL1 and AgL2). New hybrid materials based on SnO₂ and Ag(I) organometallic complexes were obtained. The microstructure, compositional characteristics and thermal stability of the composites were thoroughly studied by X-ray diffraction (XRD), X-ray fluorescent spectroscopy (XRF), Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and Thermogravimetric analysis (TGA). Gas sensor properties to 2 ppm H₂S demonstrated high sensitivity, selectivity toward other reducing gases (H₂ (20 ppm), NH₃ (20 ppm) and CO (20 ppm)) and good reproducibility of the composites in H₂S detection at low operating temperatures. The composite materials also showed a linear detection range in the concentration range of 0.12–2.00 ppm H₂S even at room temperature. It was concluded that the predominant factors influencing the sensor properties and selectivity toward H₂S in low temperature region are the structure of the modifier and the chemical state of silver. Thus, in the case of SnO₂/AgNPs reference sample the chemical sensitization mechanism is more possible, while for SnO₂/AgL1 and SnO₂/AgL2 composites the electronic sensitization mechanism contributes more in gas sensor properties. The obtained results show that composites based on nanocrystalline SnO₂ and Ag(I) organic complexes can enhance the selective detection of H₂S.     

Experience in the use of standard perfusion packings for hemosorption

A fixture for locking the perfusion packing to all types of the standard bottles with non-threaded neck is proposed. It consists of a metal ring, a yoke and two stop screws. The fixture has been clinically tested in the course of 45 hemosorption procedures.