Lipids occurrence

Table. 5. Lipid occurrence and lipid and protein content of some representative living cells...

Deficiency of natural AO in the organism brings to intensification of oxidizing processes in lipids and to occurrence in them of oxidation products in quantities that ar e above normal. 

Christie, W.W., Lipids their structure and occurrence, in Lipid Analysis, Isolation, Separation, Identification and Structural Analysis of Lipids, Vol. 5, Christie, W.W., Ed., The Oily Press, England, 2003, pp. 3-33. 

Hepatic reperfusion injury is not a phenomenon connected solely to liver transplantation but also to situations of prolonged hypoperfusion of the host s own liver. Examples of this occurrence are hypovolemic shock and acute cardiovascular injur) (heart attack). As a result of such cessation and then reintroduction of blood flow, the liver is damaged such that centrilobular necrosis occurs and elevated levels of liver enzymes in the serum can be detected. Particularly because of the involvement of other organs, the interpretation of the role of free radicals in ischaemic hepatitis from this clinical data is very difficult. The involvement of free radicals in the overall phenomenon of hypovolemic shock has been discussed recently by Redl et al. (1993). More specifically. Poll (1993) has reported preliminary data on markers of free-radical production during ischaemic hepatitis. These markers mostly concerned indices of lipid peroxidation in the serum and also in the erythrocytes of affected subjects, and a correlation was seen with the extent of liver injury. The mechanisms of free-radical damage in this model will be difficult to determine in the clinical setting, but the similarity to the situation with transplanted liver surest that the above discussion of the role of XO activation, Kupffer cell activation and induction of an acute inflammatory response would be also relevant here. It will be important to establish whether oxidative stress is important in the pathogenesis of ischaemic hepatitis and in the problems of liver transplantation discussed above, since it would surest that antioxidant therapy could be of real benefit. 

Esterbauer, H., Zollner, H. and Schaur, KJ. (1990). Aldehydes formed by lipid peroxidation mechanisms of formation, occurrence and determination. In Lipid Oxidation (ed. C. Vigo-Pelfrey) pp. 239-283. CRC Press, Boca Raton, FL. 

The Occurrence of Octadeca-trans-11-trans-13-dien-9-ynoic Acid in Plant Lipids. Austr. J. Chem. 13, 488 (I960). 

Identifying a specific natural source of lipids after GC/MS analysis is not always straightforward. The occurrence of mixtures, the unspecific FA composition of many lipid materials, the fact that materials may be physically handled during pretreatment before use and the deep changes induced by ageing, mean that extreme caution is required when interpreting FA profiles. 

The membrane is a dynamic assembly and things are diffusing rapidly in the plane of the bilayer. The middle of the bilayer has been likened to olive oil. As with oil, cooling the lipid bilayer will cause the hydrocarbons to become more ordered (structured). The side chains pack closer to each other, and the fluidity of the membrane is lower. Things that disrupt the ability of the side chains to pack in a regular fashion make the membrane more fluid (Fig. 3-4). These include high temperature, lipids with shorter chains (double bonds. The shorter lipids and the m-double bonds cause the occurrence of holes (packing defects). 

TABLE 1 Occurrence of lipid-soluble alkaloids in amphibians... 

Pseudo-glycolipids. The interest for glycolipids is connected with their occurrence in biological systems, as well as their physicochemical properties, the two viewpoints being sometimes correlated. For example in membranes, lipid rafts are sub-domains which contain liquid-ordered phases.73... 

---