Effect of Lipids

The effect of lipids on the volatiles formed in foods has been reviewed by Whitfield.149 

Lipid oxidation products react with proteins and other amino compounds to form brown substances, similar to melanoidins. The formation of such brown substances was reviewed already at the first Maillard Symposium.150 The pigments formed are partly soluble in chloroform-methanol and partly insoluble, whereas true melanoidins are largely water-soluble. As most brown pigments of fish muscle are soluble in benzene-methanol and only to a lesser extent in water, the implication is that here oxidised lipid-protein interactions are more important than Maillard browning due to ribose-amino acid interactions. 

Of the different types of lipids in foods, the phospholipids, being more unsaturated, are particularly important in relation to aroma formation in meat.151 The aroma of cooked meat was not affected by the prior extraction of triglycerides with hexane, but the use of a more polar solvent (chloroform-methanol), which extracts all lipids, including phospholipids, resulted, after cooking, in the replacement of the meaty aroma by a roast or biscuit-like one. This was reflected in the volatiles, the dominant aliphatic aldehydes and alcohols being replaced by alkylpyrazines. This implies that the participation of the lipids in the Maillard reactions inhibited the formation of heterocyclic compounds. 

Thiazoles with long alkyl chains in the 2-position provide evidence of the interaction of lipid oxidation products with Maillard intermediates. The presence of such thiazoles has been reported for fried chicken, roast beef, and fried potatoes (see Mottram152). Thiophens with long alkyl chains in the 2-position have also been encountered. They were obtained when phospholipid was added to a cysteine-ribose system.153 Lipid degradation to the 2,4-dienal, followed by reaction with H2S, was thought to be responsible.154 

Browning due to interaction of oxidised lipids and proteins occurs in vivo, the brown pigment deposited in tissues being termed lipofuscin or ceroid. The appearance of brown discoloration in the adipose tissues of, inter alia, pig, mink, and chicken, has been called the yellow fat disease . Ceroid accumulates slowly and has therefore been described as the age pigment . 

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Liden, K., Takahasi, C. and Nelson, D.E. 1995 The effects of lipids in stable carbon isotope analysis and the effects of NaOH treatment on the composition of extracted bone collagen. Journal ofArchaeological Science 22 321-326. 

D. (1978). Effect of lipid vesicle (liposome) encapsulation of methotrexate on its chemotherapeutic efficacy in solid rodent tumors. Cancer Res., 38, 2848-2853. 

A. (1990b). Effect of lipid composition on the in vivo integrity of doxorubicin-containing liposomes. Two pathways for sustained release of doxorubicin. Submitted. 

Corti R, Fayad ZA, Fuster V, Worthley SG, Helft G, Chesebro J, Mercuri M, Badimon JJ. Effects of lipid-lowering by simvastatin on human atherosclerotic lesions a longitudinal study by high-resolution, noninvasive magnetic resonance imaging. Circulation 2001 104(3) 249. 

Bonithon-Kopp, C. et al.. Combined effects of lipid peroxidation and antioxidant status on carotid atherosclerosis in a population aged 59-71 years The EVA (Etude sur le Vieillisement Arteriel) study. Am. J. Clin. Nutr, 65, 121, 1997. 

The difficulties in investigating the influence of permeant size on permeability arise from the fact that changes in permeant size are usually accompanied by changes in lipophilicity, with the latter effects often overshadowing the effects of permeant size alone. Xiang and Anderson studied the effects of lipid chain packing and permeant size and shape on permeability across lipid bilayers [163]. They carried out the experiments in gel... 

Viel, G.T., Yang, Q., Lundahl, P, Ensing, K., and de Zeeuw, R. A., Size-exclusion chromatographic reconstitution of the bovine brain benzodiazepine receptor. Effects of lipid environment on the binding characteristics, /. Chromatogr. A, 776, 101, 1997... 

TABLE 9-8. Effects of Lipid-Lowering Drugs on Serum Lipids at FDA-Approved Doses... 

TABLE 9-9. Formulation, Dosing, and Common Adverse Effects of Lipid-Lowering Drugs... 

Schreier, S. Frezzatti, W. A., Jr. Araujo, R S. Chaimovich, H. Cuccovia, I. M., Effect of lipid membranes on the apparent pK of the local anesthetic tetracaine Spin label and titration studies, Biochim. Biophys. Acta 769, 231-237 (1984). 

Clarke RJ (1997) Effect of lipid structure on the dipole potential of phosphatidylcholine bilayers. Biochim Biophys Acta-Biomembr 1327(2) 269-278... 

Figure 7 PCL recordings in ACL system. 1, blank 2-5, effects of lipid extracts from, respectively, 20, 40, 60, and 80 i.L of blood plasma from a healthy blood donor. (From Ref. 28.)...

The adjuvant effect of lipid A on the immunogenicity of polymeric lipospheres was also tested [14], Incorporation of lipid A in PCL lipospheres had no effect on the IgG ELISA titers. However, in the case of PLA lipospheres, lipid A significantly increased the immune response to R32NS1 malaria antigen, resulting in IgG levels similar to those obtained with PCL lipospheres. The adjuvant effect of lipid A incorporated in PLA lipospheres was observed even after 1600-fold dilution of the rabbit sera [14],... 

Elamrami, K. and Blume, A. (1983). Effect of lipid phase transition on the kinetics of H 1 /OH diffusion across phosphatidic acid bilayers, Biochim. Biophys. Acta, 727, 22-30. 

Bienvenue, E., Boudou, A., Desmazes, J. P., Gavach, C., Georgescauld, D., Sandeaux, J., Sandeaux, R. and Seta, P. (1984). Transport of mercury compounds across bimolecular lipid membranes effect of lipid composition, pH and chloride concentration, Chem.-Biol. Interact., 48, 91-101. 

For the NO studies that show inhibition of lipid peroxidation, we used HL-60 cells made more oxidizable by adding 32 pM docosahexaenoic acid (22 6q)3 ) to the growth media. When unenriched cells were examined, inhibition of oxidation was qualitatively identical, but the magnitude of the effect was less, and therefore more difficult to measure. The effect of lipid unsaturation will be developed below. 

Kirby C, Gregoriadis G. The effect of lipid composition of small unilamellar liposomes containing melphalan and vincristine on drug clearance after injection into mice. Biochem Pharmacol 1983 32(4) 609. 

Lupulescu AP, Birmingham DJ. 1975. Effect of lipid solvents on protein, DNA, and collagen synthesis in human skin An electron microscopic autoradiographic study. J Invest Dermatol 65(5) 419-422. 

In a study of the effects of lipid extracted toxins (GT-1, GT- , and GT-3) from toxicus on guinea pig ileal smooth muscle... 

The foam-negative effects of lipids can also be counteracted with the addition of a lipid-binding protein, wheat puroindoline (PIN), to beer. The PIN may bind the residual free lipids in such a way that they can no longer destabilize the foam. (Adapted from Cooper et ah, 2002)... 

W6. Wills, E. D., Effects of lipid peroxidation on membrane-bound enzymes of the endoplasmic reticulum. Biochem. J. 123, 983-991 (1971). 

Lipid membranes are quite deformable, allowing water and head groups into their interiors when perturbed. A "water defect" is shown in Figure 1C, where water and lipid head groups enter the hydrophobic interior of only one of the bilayer leaflets. Figure ID shows a "water pore," where both leaflets are perturbed. At the molecular level, pore and defect formation are directly related to specific lipid-lipid interactions. It is important to understand the free energy required for pore formation in membranes and the effect of lipid composition on the process. In Section 3 of this chapter, we review recent MD studies of the thermodynamics of pore formation. 

EFFECT OF LIPID MONOLAYERS ON EVAPORATION RATES OF LIQUIDS... 

The role of the antioxidant properties of vitamins C, E, and p-carotene in the prevention of cardiovascular disease has been the focus of several recent studies. Antioxidants reduce the oxidation of low-density lipoproteins, which may play a role in the prevention of atherosclerosis. However, an inverse relationship between the intake or plasma levels of these vitamins and the incidence of coronary heart disease has been found in only a few epidemiological studies. One study showed that antioxidants lowered the level of high-density lipoprotein 2 and interfered with the effects of lipid-altering therapies given at the same time. While many groups recommend a varied diet rich in fruits and vegetables for the prevention of coronary artery disease, empirical data do not exist to recommend antioxidant supplementation for the prevention of coronary disease. 

Meyer and Overton discover effect of lipid solubility on anesthetic action Fischer and von Mering identify hypnotic properties of barbiturates (see 1882)... 

Abra, R.M., Mihalko, P.J., and Schreier, H. (1990). The effect of lipid composition upon the encapsulation and in vitro leakage of metaprotemol sulfate from 0.2 im diameter, extruded, multilamellar liposomes. J. Control. Release, 14, 71-78. 

Animal models permit the investigation of the antitumoral effect of lipids A and LPS [57], We will first consider the acute effects observed after the first injection of lipids A or LPS. In each case, their relevance to an antitumoral activity will be discussed. 

One of the most important effects of lipids A on tumor growth occurs through the modulation of cytokine production. 

Other cytokines are involved in the effect of lipid A on tumor growth. OM-174 decreases TGF-P mRNA and protein in rat PROb tumors [107]. ONO-4007 increases TNF-a, IL-ip, IL-12, and 11-6 while decreasing TGF-P levels [108]. The secretion of IL-12 by dendritic cells is also induced by microbial products like LPS [109], These cytokines have further effects on other cell types, which could be considered as indirect effects of LPS. In this respect, 11-6 and IL-12 increase LAK induction [110]. 

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