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Lipid diene conjugation in human saliva

Fong, Christopher Yik Fai; (1992) Lipid diene conjugation in human saliva. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Abstract

Diene conjugation (DC) has been widely recognised as a marker of free radical attack on polyunsaturated lipids. Octadeca-9-cis,lltransdienoic acid (18;2(9c,lit)) which is a non-hydroxy, non-hydroperoxy isomer of linoleic acid (18:2(9,12)) accounts for over 95% of all DC in human tissues and tissue fluids studied. This isomer can be generated by free radical mechanisms. The % molar ratio (%MR) of 18:2(9c,llt)/18:2(9,12) has also been used as a free radical marker. The first objective of the work embodied in this thesis was to establish the presence of DC lipids, in particular 18:2(9c,lit), in both esterified and non-esterified lipid fractions of fresh human saliva. It was established that 18:2(9c,llt) and other specific DC products could be generated in vitro by incubating saliva. The biological variables affecting 18:2(9c,llt) generation were studied. The mechanism by which 18:2(9c,llt) and other DC products were generated in vitro and in vivo was investigated. Studies involving antibacterial agents and bacterial culture revealed that 18:2(9c,llt) and other conjugated dienes were generated enzymically by bacteria present in saliva. The possibility that this was, at least in part, a free-radical-mediated process could not be ruled out. Since the bacteria thought to be responsible are widely distributed in humans, the above new findings have direct relevance to the measurement and interpretation of 18:2(9c,llt) and %MR. A pilot study was carried out to investigate the effects of diets on the distribution of 18:2(9,11) in both human serum and saliva. Finally, a preliminary clinical study was carried out to assess the possible implication of some of the above findings on the salivary measurements of 18:2(9,11) and %MR.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: Lipid diene conjugation in human saliva
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Thesis digitised by ProQuest
Keywords: Pure sciences; Polyunsaturated lipids
URI: https://discovery.ucl.ac.uk/id/eprint/10111915
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