Levels of expression and immunogenicity of attenuated Salmonella enterica serovar typhimurium strains expressing Escherichia coli mutant heat-labile enterotoxin

The effects of heterologous gene dosage as well as Salmonella typhimurium strain variability on immune response toward both the heterologous antigen, the nontoxic mutant of the Escherichia coli heat-labile enterotoxin LTK63, and the carrier Salmonella strain have been analyzed, Effects of a single integration into the host DNA and different-copy-number episomal vectors were compared in S. typhimurium Delta cya Delta crp Delta asd strains of two different serotypes, UK-1 and SR-11, Expression of the enterotoxin in the different Salmonella isolates in vitro was found to vary considerably and, for the episomal vectors, to correlate with the plasmid copy number, LTK63-specific serum immunoglobulin G (IgG) and mucosal immunoglobulin A (IgA) antibodies were highest in mice immunized with the high-level-expression strain. High anti-LTK63 IgG and IgA titers were found to correspond to higher anti-Salmonella immunity, suggesting that LTK63 exerts an adjuvant effect on response to the carrier. Statistically significant differences in anti-LTK63 immune response were observed between groups of mice immunized with the attenuated Delta cya Delta crp UK-I and SR-II derivatives producing the antigen at the same rate, These data indicate that the same attenuation in S, typhimurium strains of different genetic backgrounds can influence significantly the immune response toward the heterologous antigen. Moreover, delivery of the LTK63 enterotoxin to the immune system by attenuated S. typhimurium strains is effective only when synthesis of the antigen is very high during the initial phase of invasion, while persistence of the S. typhimurium strain in deep tissues has only marginal influence.66122423

A report on 528 intragenic deletions detected in DMD and BMD patients by an Italian collaborative study.

The results of a collaborative study involving about one third of the total DMD and BMD cases living in the Italian territory are reported. The analysis of the breakpoint frequency by intron revealed significant differences among regional groups of DMD patients (for introns 2, 11 and 50 in Sardinia and for introns 9 and 45 in northeastern Italy), whereas no regional differences were observed among regional groups of BMD patients. These differences involve the same Italian regions which previous studies, performed by different markers, identified as "genetically differentiated". The data support the possibility of a differential distribution among populations of some intronic sequences, facilitating the origin of deletion breakpoints within the dystrophin gen

DEVELOPMENT OF PROCESS, SIMULATION OF CONCENTRATION PROCESS OF OXIDIZED IRON AND CHROMIUM ORES IN SUSPENSION HYDROCYCLONES

There the hydrocyclone process has been studied as alternative for the jigging in view to decrease of losses of valuable components in concentration of oxidized iron ores. The study of flow pattern by means of air-buble flares of rate transducers and by means of photography allowed to confirm the existence of high-rate (up to 1,2 m/s) local radial flow in the field of edge of outlet. The separation mechanism in two- and three-product (with coaxial tubes) hydrocyclones has been offered. The optimum relations of lengthes of internal branch pipes and of cylindrical part of hydrocyclone have been ascertained. The factors which provide for maximum of separation density have been recommended on the basis of methods of hydromechanics and mechanics. The simulator of hydrocyclone process (as the set of regression equations) and the calculation procedure of loads of regeneration system and of expectable production indicators of concentration have been developed. The effectiveness of developed concentration process has been checked under the industrial conditions. The developed concentration process of chromium ores has been accepted for use in the Don Ore Mining-and-Processing Enterprise. The study results may by used for design, for prediction estimation of concentrating capacity of ores and in the educational processAvailable from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio