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Observation of endotoxins neutralization by polymyxin with light microscope

By Ron Dixon, H L Hing and A Sahalan


The outer membrane component of Gram negative bacteria are composed of lipopolysaccharides\ud (LPS). LPS are endotoxins which often caused the fatal condition known as septic\ud shock. However, a peptide antibiotic known as polymyxin B (PMB) was detected to neutralize these\ud endotoxin molecules. However, due to its toxicity, PMB remains unused as a treatment for endotoxic\ud shock. But it has been accepted widely as a model substance in studying LPS neutralization. At\ud present, method of observing LPS alone or LPS interaction in the presence of PMB is carried out\ud with an electron micrograph. This laborious method requires highly skilled technicians to conduct\ud simple experiment. However, a simplifi ed and rapid method was introduced by using the light\ud microscope. LPS staining was carried out with Sudan black. As a result a relatively good image\ud for observation was obtained. The LPS was seen as dark ribbon like strand forming loops. Upon the exposure to PMB, the LPS strands were broken down into small fragmented molecules.\ud This method has given a simple, low cost and quick observation technique. It also provides a good platform for screening many new compounds that neutralizes LPS

Topics: C521 Medical Microbiology, C500 Microbiology
Publisher: Society of Microscopy
Year: 2009
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