Synthesis of HTPB and CTPB Prepolymers by Anionic …

An early response of L. pneumophila strain 2064 to the presence of host cells involves de novo synthesis of increasing amounts of HtpB (Fernandez et al., ; see below). However, an isogenic, salt-tolerant, avirulent derivative of 2064 was unable to respond, and showed no de novo synthesis of HtpB in the same experimental conditions used for 2064 (Fernandez et al., ). This observation provided an additional link between HtpB and L. pneumophila virulence, and suggested that HtpB might be required at an early stage of the infection process, even before L. pneumophila is internalized. In conclusion, the abilities to produce new HtpB in response to host mammalian cells, and display HtpB on the bacterial cell surface, are lost in avirulent legionellae.

Facile synthesis of novel HTPBs and EHTPBs with high …

Synthesis of hydroxyl-terminated polybutadiene …

Preparation of Hydroxyl-Terminated Polybutadiene …

High temperature protein B is induced by heat shock. Increased levels of HtpB were detected in L. pneumophila (Lema et al., ) and in L. pneumophila and E. coli (Hoffman et al., ) upon temperature increases. However, the maximum increase in HtpB expression upon heat shock was ~twofold, and at all temperatures tested HtpB remained as one of the most abundant proteins in L. pneumophila. This constitutes a pattern of heat shock that is different from the pattern typically seen in other bacteria (e.g., E. coli as shown in Hoffman et al., ), where the basal levels of chaperonin are low and a sharp increase is observed at high temperatures. Clearly, HtpB is not a typical Hsp in L. pneumophila. In addition, HtpB seems to be induced in virulent L. pneumophila by the presence of mammalian host cells (monocytes and L929 cells), as demonstrated by Fernandez et al. () using pulse radiolabeling in cycloheximide-treated, Legionella-infected cells. The induced synthesis of new HtpB did not require bacterial internalization (inhibited with cytochalasin D), suggesting that contact with host cells was sufficient to trigger the response. Finally, Fernandez et al. () determined by immunoelectron microscopy that HtpB epitopes were present on the phagosomal membrane and the cytoplasm of the infected cell.

Synthesis and characterization of polyurethane based …

It turns out that polyamines enhance the intracellular growth of L. pneumophila, whereas the inhibition of their synthesis impairs such growth. In addition, according to our bioinformatics analysis of the L. pneumophila genomes, L. pneumophila lacks 10 of the 12 enzymes described so far that are involved in the biosynthesis of polyamines in bacteria. This was a striking finding suggesting that L. pneumophila is incapable of synthesizing all polyamines, and that it might acquire them directly from its hosts. Therefore, we have hypothesized that one of the functions performed by the HtpB released into the cytoplasm of host cells could be to (through its interaction with SAMDC) increase the intracellular pool of polyamines, which L. pneumophila subsequently takes up. We are currently testing this hypothesis by: (i) measuring the levels of polyamines in CHO-htpB cells expressing and not expressing HtpB, as well as in L. pneumophila-infected cells, and (ii) determining whether HtpB extends the half-life of mammalian or amebal SAMDC, protecting it from early natural degradation. For now the role of polyamines on the physiology of L. pneumophila, and the hypothetical role of HtpB in the process constitutes an unfolding story.

terminated Polybutadiene By Anionic Polymerization: 2 :

Synthesis of Ferrocene Grafted Hydroxy Terminated Polybutadiene ..

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