Experimental and theoretical investigations of stochastic oscillatory phenomena in a nonrelativistic electron beam with a virtual cathode

Results are presented from experimental investigations of oscillatory phenomena in an electron beam with a virtual cathode in a diode gap with a decelerating field. Experiments have revealed a stochastic broadband generation of the microwave oscillations of a virtual cathode in a decelerating field. Numerical simulations based on a simple one-dimensional model have shown that the onset of the stochastic generation and the broadening of the oscillation spectrum with increasing beam deceleration rate are governed by the processes of regrouping of the electrons in a beam with a virtual cathode.     

Disinfectants and main sanitary and preventive measures for protection of ventilation and air-conditioning systems from Legionella contamination

The study was devoted to selection and assessment of disinfecting preparations for prevention of contamination by Legionella. Using system of criteria for quality assessment of disinfectants, seven newdomestic ones belonging to quaternary ammonium compounds class or to oxygen-containing preparations and designed for disinfecting of air-conditioning and ventilation systems were selected. Antibacterial and disinfecting activities of working solutions of disinfectants were tested in laboratory on the test-surfaces and test-objects of premises' air-conditioning and ventilation systems contaminated with Legionella. High antimicrobial and disinfecting activity of new preparations "Dezactiv-M", "ExtraDez", "Emital-Garant", "Aquasept Plus", "Samarovka", "Freesept", and "Ecobreeze Oxy" during their exposure on objects and materials contaminated with Legionella was shown. Main sanitary and preventive measures for defending of air-conditioning and ventilation systems from contamination by Legionella species were presented.     

Tenascin in the human intervertebral disc: alterations with aging and disc degeneration

Our objective for this study was to determine the presence and distribution of tenascin in the human intervertebral disc. The tenascins are a family of extracellular matrix proteins with repeated structural domains homologous to epidermal growth factor, fibronectin type III and the fibrinogens. Little is known about the presence of this protein in the disc. Ten normal human discs donated from subjects newborn to 15 years old, 10 control discs from adult donors aged 24-41 years, and 11 surgical disc specimens from patients aged 26-76 years were examined for immunolocalization of tenascin. In young discs, tenascin was localized throughout the annulus; in the nucleus, localization was confined to pericellular matrix. In adult control and degenerating disc specimens, tenascin in the annulus was localized primarily in pericellular matrix regions encircling either single cells or clusters of disc cells; in rare instances localization was more diffuse in the intraterritorial matrix. In young, healthy disc, tenascin was abundant throughout the annulus. In contrast, degenerating discs in adults showed a localization restricted to the pericellular, and rarely, more restricted intraterritorial matrix. These observations indicate that changes in the amount and distribution of tenascin may have a role in disc aging and degeneration, possibly by modulating fibronectin-disc-cell interactions, and causing alterations in the shape of disc cells.     

The chemokine,CXCL16, and its receptor,CXCR6, are constitutively expressed in human annulus fibrosus and expression of CXCL16 is up-regulated by exposure to IL-1ß in vitro

Chemokines are an important group of soluble molecules with specialized functions in inflammation. The roles of many specialized chemokines and their receptors remain poorly understood in the human intervertebral disc. We investigated CXCL16 and its receptor, CXCR6, to determine their immunolocalization in disc tissue and their presence following exposure of cultured human annulus fibrosus cells to proinflammatory cytokines. CXCL16 is a marker for inflammation; it also can induce hypoxia-inducible factor 1α (HIF-1α), which is a phenotypic marker of heathy nucleus pulposus tissue. We found CXCL16 and CXCR6 immunostaining in many cells of the annulus portion of the disc. Molecular studies showed that annulus fibrosus cells exposed to IL-1ß, but not TNF-α, exhibited significant up-regulation of CXCL16 expression vs. control cells. There was no significant difference in the percentage of annulus cells that exhibited immunolocalization of CXCL16 in grade I/II, grade III or grade IV/V specimens. The presence of CXCL16 and its receptor, CXCR6, in the annulus in vivo suggests the need for future research concerning the role of this chemokine in proinflammatory functions, HIF-1α expression and disc vascularization.     

The use of liposomes for detection of the surface lipopolysaccharide antigen, Vibrio cholerae cells, and antibodies against them

A test system for determination of Vibrio cholerae cells, surface O-antigen, and antibodies against them was developed on the basis of complement-dependent lysis of liposomes sensitized by the lipopolysaccharide-dependent antigen from Vibrio cholerae 569B. The factors that affect the function of the liposomal reagent were studied, and the conditions for detecting antibodies and antigenic material were optimized. This system is highly specific and sensitive to be used for the determination of anticholeraic antibodies (30-50 times as effective as agglutination tests), lipopolysaccharide antigen (100 ng/ml, which corresponded to 3.0 ng of lipopolysaccharide in the sample studied), and Vibrio cholerae cells (3.3 x 10(7) m.b./ml, which corresponded to 10(6) m.b. in sample). It takes 30-40 min to detect the lipopolysaccharide antigen and 90 min to detect V. cholerae cells.     

A Remarkable New Family of Jurassic Insects (Neuroptera) with Primitive Wing Venation and Its Phylogenetic Position in Neuropterida

Background

Lacewings (insect order Neuroptera), known in the fossil record since the Early Permian, were most diverse in the Mesozoic. A dramatic variety of forms ranged in that time from large butterfly-like Kalligrammatidae to minute two-winged Dipteromantispidae.

Principal Findings

We describe the intriguing new neuropteran family Parakseneuridae fam. nov. with three new genera and 15 new species from the Middle Jurassic of Daohugou (Inner Mongolia, China) and the Early/Middle Jurassic of Sai-Sagul (Kyrgyzstan): Parakseneura undula gen. et sp. nov., P. albomacula gen. et sp. nov., P. curvivenis gen. et sp. nov., P. nigromacula gen. et sp. nov., P. nigrolinea gen. et sp. nov., P. albadelta gen. et sp. nov., P. cavomaculata gen. et sp. nov., P. inflata gen. et sp. nov., P. metallica gen. et sp. nov., P. emarginata gen. et sp. nov., P. directa gen. et sp. nov., Pseudorapisma jurassicum gen. et sp. nov., P. angustipenne gen. et sp. nov., P. maculatum gen. et sp. nov. (Daohugou); Shuraboneura ovata gen. et sp. nov. (Sai-Sagul). The family comprises large neuropterans with most primitive wing venation in the order indicated by the presence of ScA and AA1+2, and the dichotomous branching of MP, CuA, CuP, AA3+4, AP1+2. The phylogenetic position of Parakseneuridae was investigated using a phylogenetic analysis of morphological scoring for 33 families of extinct and extant Neuropterida combined with DNA sequence data for representatives of all extant families. Parakseneuridae were recovered in a clade with Osmylopsychopidae, Prohemerobiidae, and Ithonidae.

Conclusions/Significance

The presence of the presumed AA1+2 in wings of Parakseneuridae is a unique plesiomorphic condition hitherto unknown in Neuropterida, the clade comprising Neuroptera, Megaloptera, Raphidioptera. The relative uncertainty of phylogenetic position of Parakseneuridae and the majority of other families of Neuroptera reflects deficient paleontological data, especially from critical important periods for the order, earliest Triassic and latest Triassic/earliest Jurassic.     

Interaction between dialkylamines and bacterial agmatinase]

It was demonstrated that aliphatic dialkylamines are more effective inhibitors of bacterial agmatinase than monoalkylamines and differ from the latter by the type of inhibition. The dependence of the inhibition constant on the hydrophobicity of the compounds tested was studied. The type of this dependence was found to be different for long- and short-radical dialkylamines, the correlation equation appearing as 1g(1/Ki) = 0,33 1gPo + (2,3 +/- 0,2) for the former compounds and as 1g(1/Ki) = 1,0 1gPo + (2,2 +/- 0,2) for the latter. The enzyme inhibition by the inhibitors tested was dependent on pH: e. g. with an increase in pH the inhibiting effect was decreased. It was assumed that the inhibitor sorption by agmatinase is of hydrophobic-ionic type and that the active site of the enzyme contains two hydrophobic zones separated by a nucleophylic group. The length of the hydrophoblic zones was estimated.     

Carbamyl phosphate and citrulline formation by phototrophic bacteria

The purple bacteria Ectothiorhodospira shaposhnikovii and Rhodospirillum rubrum are capable of synthesizing citrulline in the presence of ammonium hydrocarbonate, ornithine, ATP and Mg2+ ions. Citrulline biosynthesis by these phototrophic bacteria is presumed to be catalysed by carbamate kinase and ornithine transcarbamoylase. Therefore, certain phototrophic bacteria can assimilate carbon dioxide and ammonia for biosynthesis of amino acids, in particular, citrulline and, apparently, arginine.