Genetic characterization of toxigenic Vibrio cholerae non-O1/non-O139 strains, isolated in the Middle Asia

Here, we report on the characterization of 22 clinical toxigenic V. cholerae non-O1/non-O139 strains isolated in the Middle Asia (Uzbekistan) in 1971–1990. PCR analysis has revealed that these strains contain the main virulence genes such as ctxA, zot, ace (CTXφ); rstC (RS1φ); tcpA, toxT, aldA (pathogenicity island VPI), but they lack both pandemic islands VSP-I and VSP-II specific to epidemic strains of O1 serogroup of El Tor biotype and O139 serogroup. Only two of the twenty two toxigenic strains have tcpA gene of El Tor type, one strain has tcpA gene of classical type, while nineteen other strains carry a new variant of this gene, designated as tcpA ^uzb. Nucleotide sequences analysis of virulence genes in toxigenic V. cholerae non-O1/non-O139 strains from Uzbekistan showed that they differ significantly from the sequences of these genes in epidemic O1 and O139 strain indicating that they belong to a separate line of evolution of virulent V. cholerae strains. For the first time it is shown that V. cholerae non-O1/non-O139 toxigenic strains of different serogroups may belong to the same clone.     

Etiology and microbiological diagnosis of nosocomial pneumonia in newborns]

A comparative analysis of the cases of ventilator-associated pneumonia (VAP) among premature infants in intensive care units and premature infant nurseries in 1994 (group I) and 1999 (group II) is presented. It was shown that the number of the cases of ventilator-associated pneumonia in the premature infants of group. I was 2,4 times higher than that in the group II (45.8 and 19.2 per cent respectively). A marked difference in the species pattern of the pathogens isolated from the endobronchial aspirate in 1994 and 1999 was observed. The species pattern of the isolates from the respiratory tract (Pseudomonas aeruginosa--40 per cent; Klebsiella pneumoniae--31 per cent; Staphylococcus epidermidis and Enterococcus--rare) showed that the pneumonia were nosocomial. The revealed similarity of the species patterns of the microflora in various parts of the respiratory tract and the throat posterior wall made it possible to consider the isolates of the throat posterior wall as a relative guide for confirming the etiological diagnosis of nosocomial pneumonia.     

A comparative study of delayed hypersensitivity due to mycobacteria and their isolated protein fractions

The role of intracellular protein fractions, isolated from M. tuberculosis virulent strains in the process of the electrophoretic separation, in the development of delayed hypersensitivity reactions has been studied. Low reactogenicity of protein fractions has been established on the basis of the development of faint immunopathological reactions in sensitized animals. High-molecular fraction 1 may be used as a sensitive preparation for the differentiation of individual mycobacterial species.     

Air-directed attachment of coccoid bacteria to the surface of superhydrophobic lotus-like titanium

Superhydrophobic titanium surfaces fabricated by femtosecond laser ablation to mimic the structure of lotus leaves were assessed for their ability to retain coccoid bacteria. Staphylococcus aureus CIP 65.8^T, S. aureus ATCC 25923, S. epidermidis ATCC 14990^T and Planococcus maritimus KMM 3738 were retained by the surface, to varying degrees. However, each strain was found to preferentially attach to the crevices located between the microscale surface features. The upper regions of the microscale features remained essentially cell-free. It was hypothesised that air entrapped by the topographical features inhibited contact between the cells and the titanium substratum. Synchrotron SAXS revealed that even after immersion for 50 min, nano-sized air bubbles covered 45% of the titanium surface. After 1 h the number of cells of S. aureus CIP 65.8^T attached to the lotus-like titanium increased to 1.27 × 10⁵ mm^?2, coinciding with the replacement of trapped air by the incubation medium.     

Cytogenetic effects of low doses of radiation in mammalian cells: analysis of the hypersensitivity phenomenon and induced resistance

The induction of cytogenetic damage after irradiation of chinese hamster cells and human melanoma cells within a dose range 1-200 cGy was studied. The anaphase and metaphase analysis of chromosome damage and micronuclei test were applied. The hypersensitivity (HRS) at doses below 20 cGy and the increased radio-resistence at higher doses (IR) were shown with all cytogenetic critheria for both cell lines. The phenomenon of HRS/IR was reproduced in synchronic as well as in a synchronic population of chinese hamster cells. This fact shows that HRS was caused by high radiosensitivity of all cells and can not be explained by any differential sensitivity of cells in different phase of the cell cycle. So it was supposed that the increasing radio-resistence is determined by the inclusion of the inducible repair processes in all cells. This conclusion consents with the facts, that there was no evidence of HRS on dose-effect curves and that some parts of pre-existent damage was repaired after preliminary irradiation with low doses (1-20 cGy) which induce repair processes. It can be concluded that same inducible repair processes an analogous in mechanisms underlying in the base of HRS/IR phenomenon and adaptive response.     

Aggregation of Nanosized Hydroxyapatite Particles and Inhibition of Cell Adhesion on this Bio-Active Material as Key Factors that Limit its Biointegration

Biophysics - Abstract—Different synthetic calcium phosphate compounds are used as osteoplastic materials for filling of bone defects during surgical reconstruction of bone. Synthetic...     

Air-directed attachment of coccoid bacteria to the surface of superhydrophobic lotus-like titanium

Superhydrophobic titanium surfaces fabricated by femtosecond laser ablation to mimic the structure of lotus leaves were assessed for their ability to retain coccoid bacteria. Staphylococcus aureus CIP 65.8T, S. aureus ATCC 25923, S. epidermidis ATCC 14990T and Planococcus maritimus KMM 3738 were retained by the surface, to varying degrees. However, each strain was found to preferentially attach to the crevices located between the microscale surface features. The upper regions of the microscale features remained essentially cell-free. It was hypothesised that air entrapped by the topographical features inhibited contact between the cells and the titanium substratum. Synchrotron SAXS revealed that even after immersion for 50 min, nano-sized air bubbles covered 45% of the titanium surface. After 1 h the number of cells of S. aureus CIP 65.8T attached to the lotus-like titanium increased to 1.27×10(5) mm(-2), coinciding with the replacement of trapped air by the incubation medium.