225 research outputs found

    Lipid Inclusions in Mycobacterial Infections

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    The M. tuberculosis Phosphate-Binding Lipoproteins PstS1 and PstS3 Induce Th1 and Th17 Responses That Are Not Associated with Protection against M. tuberculosis Infection

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    The M. tuberculosis phosphate-binding transporter lipoproteins PstS1 and PstS3 were good immunogens inducing CD8+ T-cell activation and both Th1 and Th17 immunity in mice. However, this antigen-specific immunity, even when amplified by administration of the protein with the adjuvant LTK63 or by the DNA priming/protein boosting regimen, was not able to contain M. tuberculosis replication in the lungs of infected mice. The lack of protection might be ascribed with the scarce/absent capacity of PstS1/PstS3 antigens to modulate the IFN-γ response elicited by M. tuberculosis infection during which, however, PstS1-specific IL-17 secreting cells were generated in both unvaccinated and BCG-vaccinated mice. In spite of a lack of protection by PstS1/PstS3 immunizations, our results do show that PstS1 is able to induce IL-17 response upon M. tuberculosis infection which is of interest in the study of anti-M. tuberculosis immunity and as potential immunomodulator in combined vaccines

    Influences of Various Parameters on Sound Absorption Properties of Vetiver Grass Fiber-based Developed Composite Material

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    422-429Recently, the trend of natural fibers based eco-friendly materials utilization in the field of acoustic application has been growing rapidly in place of traditional synthetic materials to counter environmental issues, due to their cheap processing cost and other several advantages. In this work, sound absorption and thermal insulation properties of the vetiver grass (Chrysopogon zizanioides) based material have been investigated. Efforts have been carried out in developing porous vetiver grass fibers based composite material. The developed samples tested for the sound absorption coefficient (alpha) over a wide range of frequencies (100 Hz – 4000 Hz) by the reverberation chamber method as per IS 8225-1987/ISO 354- 2003/ASTM 423-909-19 and noise reduction coefficient (NRC) also been calculated. The experimental outcome proved that vetiver grass-based manufactured material has comparable sound absorption to already developed traditional synthetic materials. Further, two different bulk densities, thickness and fibre lengths-based samples were developed and their sound absorption acoustic performances were evaluated to see the influences of these parameters on sound absorption characteristics. Apart from these, some required physical properties as per application requirements were also discussed. However, in this study major focus has been done on acoustical properties

    Tetrahydrodipicolinate N-Succinyltransferase and Dihydrodipicolinate Synthase from Pseudomonas aeruginosa: Structure Analysis and Gene Deletion

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    The diaminopimelic acid pathway of lysine biosynthesis has been suggested to provide attractive targets for the development of novel antibacterial drugs. Here we report the characterization of two enzymes from this pathway in the human pathogen Pseudomonas aeruginosa, utilizing structural biology, biochemistry and genetics. We show that tetrahydrodipicolinate N-succinyltransferase (DapD) from P. aeruginosa is specific for the L-stereoisomer of the amino substrate L-2-aminopimelate, and its D-enantiomer acts as a weak inhibitor. The crystal structures of this enzyme with L-2-aminopimelate and D-2-aminopimelate, respectively, reveal that both compounds bind at the same site of the enzyme. Comparison of the binding interactions of these ligands in the enzyme active site suggests misalignment of the amino group of D-2-aminopimelate for nucleophilic attack on the succinate moiety of the co-substrate succinyl-CoA as the structural basis of specificity and inhibition. P. aeruginosa mutants where the dapA gene had been deleted were viable and able to grow in a mouse lung infection model, suggesting that DapA is not an optimal target for drug development against this organism. Structure-based sequence alignments, based on the DapA crystal structure determined to 1.6 Å resolution revealed the presence of two homologues, PA0223 and PA4188, in P. aeruginosa that could substitute for DapA in the P. aeruginosa PAO1ΔdapA mutant. In vitro experiments using recombinant PA0223 protein could however not detect any DapA activity
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