The modification of mammalian membrane polyunsaturated fatty acid composition in relation to membrane fluidity and function

Isolation of disaturated phosphatidylcholine with osmium tetroxide

I have reviewed recent (March 1995-December 1997) papers on human milk lipids including many on fatty acid (FA) composition. The effects of maternal diets on the profiles are apparent. However, more data on the composition of milk lipids are needed. It is noteworthy that so few papers on milk FA composition have reported analyses using high-resolution gas-liquid chromatography columns. Two of these were on milk from women in North America. The diets in North America are varied and the number of analyses few. We do not have a reliable data base showing the ranges of biologically important acids. Except for the gangliosides, few new data on the other lipids appeared during this period.

Lipids in human milk.

A primary function of the pancreas is to produce digestive enzymes that are delivered to the small intestine for the hydrolysis of complex nutrients. Much of our understanding of digestive enzymes comes from studies in animals. New technologies and the availability of the sequence of the human genome allow for a critical review of older reports and assumptions based on animal studies. This report updates our understanding of human pancreatic digestive enzymes with a focus on new insights into the biology of human proteases, lipases and amylases.

https://link.springer.com/content/pdf/10.1007%2Fs10620-006-9589-z.pdf

Human pancreatic digestive enzymes.

Methods for determining, isolating and identifying human milk lipids, together with problems associated with sampling and analysis, are described in some detail in the first 3 chapters of this book. Factors affecting total lipid content of human milk, lipid classification, fatty acids, the milk fat globule membrane, fat-soluble vitamins and nutritional aspects of human milk lipids are also extensively reviewed in Chapters 4-9.

The Lipids of Human Milk

The triglycerides of the fat globules of human milk were resolved by thin-layer chromatography on silica gel impregnated with silver nitrate The chemical structure of the glycerides was determined

Triglyceride structure of human milk fat.

The lecithins of the liver, lung, intestine, plasma, and red blood cells of rats were isolated and the major individual molecular species identified and estimated quantitatively by combined thin-la...

Molecular species of lecithins of some functionally distinct rat tissues.

Inclusion of gas chromatography of diglycerides in the various schemes proposed for sub-fractionation of natural glyceryl phosphatides increases the accuracy of identification and quantitation of the individual molecular species. This is due to its efficiency in classifying the molecular weights and proportions of the diglycerides recovered from thin-layer chromatography according to their degree of unsaturation. Determination of the complete structure of glyceryl phosphatides requires standardization of all steps of the analytical system including lipid extractions, enzyme hydrolyses, and thin-layer and gas chromatography. This presentation reviews some of the practical aspects of quantitative gas chromatography of diglycerides and fatty acids as applied in the determination of the molecular species of glyceryl phosphatides. It is shown that a good gas chromatographic technique effectively counteracts weaknesses in other analytical steps. The additional cross-checks provided by the gas chromatography of the diglycerides greatly improve the overall accuracy of the data and frequently permit perfect reconstitution of the overall and positional distribution of fatty acids, which must be the ultimate test of the success of the entire analytical scheme.

W. C. Breckenridge

Papers

Triglyceride structure of human milk fat.

Molecular species of lecithins of some functionally distinct rat tissues.

Quantitative gas chromatography in the structural characterization of glyceryl phosphatides