Changes in Lipids

A high grain moisture content and environmental temperature increase both fungi growth and activity of most enzymes. The hydrolysis of fats occurs at a faster rate than carbohydrates or proteins. Therefore, measurements of lipid damage via titrat-able acidity, pH, or free fatty acids are the most sensitive indexes to determine grain condition or soundness. These tests correlate with the evaluation of off-odors widely practiced by federal grain inspectors (Anonymous 1992) (Chapter 2). 

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Nicotinic acid is used in the treatment of hyperlipidemia. It causes various changes in lipid and lipoprotein metabolism when administered in high doses (up to 5 g/d) ... 

Nonaka, A., Manabe, T., Kyt ku, T., Tamura, K. and Tobe, T. (1990). Changes in lipid peroxide and oxygen radical scavengers in caerulein-induced acute pancreatitis. Imbalance between the offensive and defense systems. Digestion 47, 130-137. 

Stohs, S.J., Hassan, M.Q. and Murray, W.J. (1984). Effects of a-tocopherol and retinol acetate on TCDD-mediated changes in lipid peroxidation, glutathione peroxidase activity and survival. Xenobiotica 14, 533-537. 

Protein synthesis and changes in lipid and organic acid metabolism ... 

The reported (14) mechanisms of action of allelochemlcals Include effects on root ultrastructure and subsequent Inhibition of Ion absorption and water uptake, effects on hormone-induced growth, alteration of membrane permeability, changes In lipid and organic acid metabolism, inhibition of protein synthesis and alteration of enzyme activity, and effects on stomatal opening and on photosynthesis. Reduced leaf water potential Is one result of treatment with ferulic and p-coumaric acids (15). Colton and Einhellig (16) found that aqueous extracts of velvetleaf (Abutllon theophrastl Medic.) Increased diffusive resistance In soybean fGlycine max. (L.) Merr.] leaves, probably as a result of stomatal closure. In addition, there was evidence of water stress and reduced quantities of chlorophyll In Inhibited plants. 

V. Nie, C. D. Stubbs, B. W. Williams, and E. Rubin, Ethanol causes decreased partitioning into biological membranes without changes in lipid order, Arch. Biochem. Biophys. 268, 349-359 (1989). 

Y. Lavie and M. Liscovitch. Changes in lipid and protein constituents of rafts and caveolae in multidrug resistant cancer cells and their functional consequences. Glycoconj. J. 17 253-259 (2000). 

Therefore, extensive characterization is required, as the physicochemical properties of lipid nanodispersions influence not only drug incorporation and release but also the physical stability of the preparation for example, drug localization in the matrix. Several methods have to be combined for characterization to allow detection of dynamic processes such as changes in lipid modifications, particle aggregation, and the formation of nanostructures of other kinds. 

Lipid Metabolism. Next we explored changes in lipid metabolism in leaves exposed to ozone. Sterols and sterol derivatives were particularly interesting to us because they have been associated with membrane-containing fractions of leaves ( ). Changes produced in these compounds may be early events in the toxicity of ozone to plant cells. 

They do not have significant effects on the release of renin or cause long-term changes in lipid or glucose metabolism. 

Under proper processing conditions minimal alterations in the structure and bioavailability of food lipids take place. However, excessive heat and/or improper storage conditions can result in a number of degradative changes in lipids. These chemical changes have a much greater effect upon palatability than upon nutritive value. 

Sample/saliva ratio. The sample/saliva ratio is a critical parameter for volatile release in the model mouth for liquid, semi-solid, and solid foods. With liquid foods, the dilution and the change in lipid and protein concentration have an effect. With more solid types of foods, besides the effects above, salivahas an effect on the dynamics of the release. Saliva, in combination with mastication, affects the rates of mass transfer. Again, a realistic sample/saliva ratio should be chosen (e.g., in the 80 20 to 40 60 range). 

Gerber LE, Erdman JW Jr. Changes in lipid metabolism during retinoid administration. J Am Acad Dermatol 1982 6(4 Pt 2 Suppl) 664-74. 

Haba K., OgawaN., Mizukawa K., and Mori A. (1991). Time course of changes in lipid peroxidation, pre- and postsynaptic cholinergic indices, NMDA receptor binding and neuronal death in the gerbil hippocampus following transient ischemia. Brain Res. 540 116-122. 

All the above-mentioned changes in lipid composition and organization in diseased and dry skin likely contribute to an impaired stratum corneum barrier function and increased susceptibility to dry skin. However, as previously indicated, abnormalities in the process of envelope formation may also strongly influence the stratum corneum barrier integrity. Therefore, more information is required to elucidate the precise mechanisms by which stratum corneum structure and function are altered. 

Endotoxin, via cytokines, could induce marked changes in lipid metabolism [118], and HDL has been found to neutralize lipopolysaccharide (endotoxin) activity in vitro and, in animals, in vivo [116, 119, 120],... 

In addition to the studies of clinical biological changes in lipid profile levels in patients with major depression, the mechanism of lipid metabolism should be noted and discussed [133], In past studies, the main plasma lipid transport forms have been free fatty acids, triglycerides, and cholesteryl esters. 

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