G S Jamieson

Bio: G S Jamieson is an academic researcher. The author has an hindex of 1, co-authored 1 publications receiving 80 citations.

Multiple sclerosis: vitamin D and calcium as environmental determinants of prevalence. (A viewpoint). Part 1. Sunlight, dietary factors and epidemiology.

Abstract: A new theory for the etiology of multiple sclerosis (MS) has been developed which is compatible with epidemiologic, biochemical and genetic evidence. A predisposition for the disease is held to result from the development of abnormal myelin during puberty. Vitamin D and calcium are proposed as being essential for normal myelination. Curtailed supplies of these substances (from inadequate sunlight and phytate‐rich diets) correlate with geographic regions of high risk of MS. Conversely the prevalence of MS is lower where vitamin D is abundant, as in sunny climates, high altitudes, and littorals with dietaries rich in fish oils.

The mechanism of self-disinfection of the human skin and its appendages.

Abstract: 1. Four β-haemolytic strains of Streptococcus, suspended in normal saline, showed progressive increase in mortality, as the pHwas lowered from 7·5 to 5·0; below pH 5·0 the mortality was greatly accentuated.2. Ether and alcohol extracts of human skin and its appendages were powerfully, saline extracts more weakly and inconstantly, lethal to the haemolytic Streptococcus and to certain other organisms.3. The long chain fatty acids and soaps are the chief, if not the only, bactericidal constituents of skin and its appendages.4. Experiments are described illustra ting the streptococcocidal effect of various acids occurring in animal fats.5. Cystein and blood inhibit the streptoeoccocidal activity of skin fats and certain fatty acids. Ultra-violet light may increase this activity, or abolish, the inhibition exercised by cystein.6. The mechanism of the sterilizing power of fatty acids and soaps, the influence exerted by cystein, blood, and ultra-violet light on the sterilizing power, of skin fats and fatty acids, and the relationship of skin fatty acids to lysozyme are discussed.

Composition of oil

Abstract: International trade in palm oil has increased considerably over the last ten years, and so too has the trade in processed palm oil products, especially palm fractions. It is important to establish reliable purity criteria for palm oil, not only because of the commercial need to verify oil authenticity, but also to comply with foodstuff labelling legislation in many countries. Palm kernel and coconut oils both contain about 47% lauric acid. This gives the oils close similarities in physical and chemical properties. The oils do differ, however, and it is important to be able to distinguish between them. Purity problems can arise as a result of commingling of oils with one another, or as a result of fractionation perhaps coupled with subsequent blending. A research program jointly funded by the (U.K.) Ministry of Agriculture, Fisheries and Foods, the Federation of Oils, Fats & Seeds Associations Ltd (FOSFA International), and the Leatherhead Food RA, was established to study purity characteristics of the major edible vegetable oils. Forty-seven samples of crude palm oil were obtained from reliable sources, often plantation managers, together with five samples of palm olein and eight samples of palm stearin. Fifty-four palm kernel and 23 coconut oils were obtained in the laboratory from seed samples of known geographical origins and authenticities. These oil samples were analyzed for fatty acid, triglyceride, sterol and tocopherol compositions; the melting properties were also determined, and in the case of palm oil the compositions of the acids at the triglyceride 2-positions were measured. Compositional ranges will be presented for the different geographical production areas in each case and related to existing data, e.g., of PORIM and Codex. An initial statistical analysis of the results has shown that a combination of values from the carbon number analysis differentiates palm kernel and coconut oils, and can be used to decide on the proportion of each in a blend. In the case of palm oil samples suspected to be contaminated with palm fractions, it was found useful to plot melting point against iodine value, and to compute the product of the C48 triglyceride content and the palmitic acid enrichment factor.

Detection of adulteration

Abstract: A program of work is in progress to establish the levels and ranges of fatty acids and other components present in the major edible vegetable oils Authentic samples from the major producing areas for such oil have been obtained and analyzed In the case of palm oil, ranges of the fatty acid composition and of the acids at the triglyceride 2-position, have been obtained for about 40 samples These data were used to calculate enrichment factors, and triglyceride carbon number compositions, using a small computer program Comparison with experimentally determined carbon number compositions were then made Good correlations were found for whole unadulterated oils, but not for oil fractions Unfortunately, these differences were insufficient to detect contamination of palm oil by 10 or 20% levels of other oils, or of palm fractions Compositional ranges of sterols and tocopherols have also been determined on a selection from the original set of palm samples Work on sunflower seed and groundnut oils has followed the same lines, particular attention having been paid to linolenic acid and, in the case of groundnut oil, also erucic acid, levels Some groundnut kernels were found to have an oil with a component which cochromatographed with methyl erucate during fatty acid determination This unknown constituent was studied by gas chromatography-mass spectrometry, and is thought to comprise a mixture of epoxy fatty acids Analysis of the triglyceride fraction isolated from groundnut oil by thin layer chromatography removes this unknown constituent, and simplifies interpretation of the fatty acid composition of groundnut oil

Fluorescence study of the pro-oxidant effect of free fatty acids on marine lipids

Abstract: The free fatty acid (FFA) effect on the oxidative stability of marine lipids was studied by fluorescence assessment. Under different reaction conditions, including time, temperature and FFA content and type (different chain lengths and unsaturation degrees), FFAs were made to interact in model systems with a commercial marine oil (cod liver oil) and two different fish (hake and pout) white muscles. Fluorescence assessment showed a pro-oxidant effect of all types of FFA, which increased with time, temperature and FFA content in the reaction mixtures. At 30 °C a higher degree of oxidation was obtained in systems including the shorter-chain-length fatty acids (lauric and myristic) compared to systems including the longest ones (arachidic and stearic). At the same temperature an increasing pro-oxidant effect was also observed with increasing degree of fatty acid unsaturation (stearic < oleic < linoleic < linolenic). When a lower temperature (−10 °C) was tested, a differential pro-oxidant effect among fatty acids (chain length and unsaturation degree) was not observed. © 2001 Society of Chemical Industry