Infection of chickens caused by avian influenza virus A/H5N1 delivered by aerosol and other routes.

This study presents results of the study of infectivity of avian influenza virus (AIV) A subtype H5N1 strains isolated from agricultural birds across the territory of the Russian Federation and CIS countries. The results of the susceptibility of chickens to the AIV isolates delivered by the aerosol route and the dissemination of the virus in the organs of infected birds are presented. As was observed, the sensitivity of birds to AIV by the aerosol route of infection is 30 times higher than by intranasal route, 500 times higher than by the oral route and 10000 times higher than by the intragastric route of infection, which is indicative of higher permissivity of respiratory organs to AIV. The highest titres of AIV A subtype H5N1(A/Chicken/Kurgan/05/2005 strain) in aerosol-infected chickens were found in nasal cavity mucosa, lungs, cloaca, serum and kidney, where viable virus accumulation was detected by 18h post-infection (p.i.). The highest virus titres were observed 54h p.i. in lungs, serum and kidney, reaching the value of 8.16 lg EID50 /g(ml) in the lungs. The results showed that birds infected by the aerosol route developed higher titres of virus than those infected by other routes.

Effects of light environment on the induction of chlorophyll fluorescence in leaves: a comparative study of Tradescantia species of different ecotypes.

In this work, using a PAM-fluorimetry technique, we have compared effects of plant adaptation to the light or dark conditions on the kinetics of chlorophyll a fluorescence yield in Tradecantia leaves of several species (Tradescantia albiflora, Tradescantia fluminensis, Tradescantia navicularis, and Tradescantia sillamontana), which represent plants of different ecotypes. Two fluorescence parameters were used to assess photosynthetic performance in vivo: non-photochemical quenching (NPQ) of chlorophyll fluorescence (q(NPQ)) determined by energy losses in the light-harvesting antenna of photosystem 2 (PS2), and PS2 operating efficiency (Φ(PSII)). Comparative study of light-induced changes in q(NPQ) and Φ(PSII) has demonstrated that shade-tolerant Tradecantia species (T. albiflora Kunth, T. fluminensis Vell.) reveal higher capacities for NPQ and demonstrate slower transitions between the 'light-adapted' and 'dark-adapted' states than succulent species T. navicularis and T. sillamontana, which are typical habitats of semi-deserts. We analyze the photosynthetic performance of Tradescantia species in the context of their adaptabilities to variable environment conditions. The ability of shade-tolerant plants to retain a relatively long-term (∼40-60 min) 'memory' for illumination history may be associated with the regulatory mechanisms that provide the flexibility of photosynthetic apparatus in response to fluctuations of light intensity.

Inactivation and mineralization of aerosol deposited model pathogenic microorganisms over TiO2 and Pt/TiO2.

Air disinfection from bacteria and viruses by means of photocatalytic oxidation is investigated with microorganisms loaded over photocatalysts' films from aerosols. Deposition method and equipment have been developed to load Mycobacterium smegmatis , Bacillus thuringiensis , vaccinia virus, and influenza A (H3N2) virus on slides with undoped TiO(2) and platinized sulfated TiO(2) (Pt/TiO(2)). Inactivation dynamics was measured under UVA irradiation and in the dark. About 90% inactivation is reached in 30 min irradiation on TiO(2) and from 90 to 99.8% on Pt/TiO(2). The first-order inactivation rate coefficient ranged from 0.18 to 0.03 min(-1), over Pt/TiO(2) being higher than on TiO(2) for all microorganisms except Bacillus thuringiensis. The photocatalytic mineralization of Bacillus thuringiensis was performed on TiO(2) and Pt/TiO(2) with different photocatalyst and microorganism loadings. Completeness of mineralization depended on the TiO(2) to bacteria mass ratio. The rate of the photocatalytic carbon dioxide production grows with both the cell mass increase and the photocatalyst mass increase. Pt/TiO(2) showed increased rate of mineralization as well as of the inactivation likely due to a better charge carrier separation in the doped semiconductor photocatalyst. The results demonstrate that photocatalytic filters with deposited TiO(2) or Pt/TiO(2) are able to inactivate aerosol microorganisms and completely decompose them into inorganic products and Pt/TiO(2) provides higher disinfection and mineralization rates.

[Experimental evaluation of the protective properties of some nonwoven materials for respiratory protection means and prospects of their use].

The protective properties of nonwoven materials (Spandbond, SMS) used to manufacture 3-5-layer medical masks, by using model physical and bacterial test aerosols, were experimentally assessed. It was shown that the more layers of the materials, the less permeable they became for test aerosols. Three-five-layer masks made from SMS at a density of 42 g/m2 were found to have higher protective properties for oil mist and fine aerosol than those made from Spandbond at a density of 25 g/m2. Five-layer SMS materials at a density of 42 g/m2 have the highest values of bacterial aerosol retention.

[Evaluation of the protective properties of nonwoven materials for throw-away medical overalls].

The permeability of varying density felts (Spandbond, SMS, Tyvek, Sontara) for throw-away medical overalls was experimentally assessed under statistic and dynamic conditions, by using model test aerosols, including bacterial one. Their permeability was shown to decrease with the higher density of the materials under study. Laminated Span-bond contributes to an abrupt reduce in the bacterial penetration of this kind of tissues and enhances their protective properties. The felts CMC, Tyvek, Sontara, and laminated Spanbond were found to have the highest protective properties. In terms of their barrier and protective properties, the felts surpass the tissues used to make re-usable protective medical overalls.

[A new setup for the generation and studies of mono-disperse microbiological aerosols in medical-and-biological research]. / Novyi kompleks dlia polucheniia i izucheniia monodispersnykh mikrobiologicheskikh aérozolei v mediko-biologicheskikh issledovaniiakh.

A setup for the generation and studies of mono-disperse microbiological aerosols is described in the paper. Coefficients of 3 microm aerosol deposition in the respiratory tract of mice and rats were refined by using the above setup. The probability of deposition of such particles in the trachea and lungs of mice was proven to be equal to 1.2 +/- 0.1% and 2.6 +/- 0.2%, respectively. The probability for rats was equal to 3.2 +/- 0.2 and 11.8 +/- 0.9%, respectively. The distribution of deposited aerosol particles was determined by electron microscopy.