Lipopolysaccharide (LPS), a major constituent of Gram-negative bacteria, is implicated as the key factor in the development of the Systemic Inflammatory Response Syndrome (SIRS). LPS can arise from an underlying bacteraemia, but given that the majority of patients with SIRS have no detectable bacteraemia, then LPS derived from the gut must be considered. <I>Bacteroides</I> species outnumber the enterobacteria such as <I>E.coli</I> in the gut by approximately 1000-fold. Although <I>Bacteroides</I> LPS is less endotoxic, by simple arithmetic there must be as much biological potential from the LPS of <I>Bacteroides</I> as from <I>E.coli</I>. This thesis re-examines the biological activity of <I>Bacteroides</I> LPS and its possible role in the development of SIRS. LPSs were extracted from seven <I>Bacteroides</I> species by three different techniques: the phenol-water (PW), the phenol-chloroform-petroleum (PCP) and Triton-Mg<SUP>2+</SUP>. The biological activity of these <I>Bacteroides</I> LPSs was compared to that of an <I>E.coli</I> O18K<SUP>-</SUP> LPS control. In general, <I>Bacteroides</I> LPSs prepared by the PW method were found to have a significantly higher activity in a mouse lethality model, LAL assay, TNF and IL-8 induction assays, than LPS extracted by the PCP or Triton methods. <I>Bacteroides</I> LPS extracted by the PCP method had consistently low activity in all assays. LPS from <I>B.fragilis</I> NCTC 9343 and <I>B.caccae</I> had a consistently higher activity than LPS from <I>B.vulgatus</I> and <I>B.thetaiotaomicron</I> in most assays. Differences in activity between <I>B.fragilis</I> NCTC 9343 LPS grown in different media was seen. The PW method selected for greater amounts of carbohydrate and KDO and the PCP the least. Further information from sub-population studies, Percoll profiles, chemotype on PAGE and chemical analysis failed to account for differences in biological activity between extraction methods and <I>Bacteroides</I> species.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:649463 |
| Date | January 1996 |
| Creators | Delahooke, Diane Mary |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/21194 |
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