Lipid of plasma

Table 1. Fatty Acid Composition of the Total Lipids of Plasma of Rats Raised on Various Diets...

Lipids of plasma and liver homogenate were extracted by the procedure of Folch et al (1957). The fatty acid composition was determined using gas liquid chromatography. Blood glucose was measured by the o-toluidine method (Dubowsky, 1962) and liver glycogen by the method of Van Handel (1965). Proteins were determined by the biuret method of Gornall et al (1949) and liver cyclic AMP by the method of Mato and Serrano Rios (1973). 

Norberg, P. and Liljenberg, C. (1991) Lipids of plasma membranes prepared from oat root cells effects of induced water-deficit tolerance. Plant Physiol. 96,1136-1141. 

FIGURE 2 Lipids of plasma lipoproteins. Virtually all of the triglyceride and cholesterol ester of a lipoprotein is in the interior. Some unesterified cholesterol can also exist in the interior. However, all of the phospholipid is at the surface of the particle and surrounds the hydrophobic core. 

LIPOPROTEINS. Blood plasma lipoproteins are prominent examples of the class of proteins conjugated with lipid. The plasma lipoproteins function primarily in the transport of lipids to sites of active membrane synthesis. Serum levels of low density lipoproteins (LDLs) are often used as a clinical index of susceptibility to vascular disease. 

PLTP is responsible for the majority of phospholipid transfer activity in human plasma. Specifically, it transfers surface phospholipids from VLDL to HDL upon lipolysis of triglycerides present in VLDL. The exact mechanism by which PLTP exerts its activity is yet unknown. The best indications for an important role in lipid metabolism have been gained from knockout experiments in mice, which show severe reduction of plasma levels of HDL-C and apoA-I. This is most likely the result of increased catabolism of HDL particles that are small in size as a result of phospholipid depletion. In addition to the maintenance of normal plasma HDL-C and apoA-I concentration, PLTP is also involved in a process called HDL conversion. Shortly summarized, this cascade of processes leads to fusion of HDL... 

Due to the absence of human models for PLTP deficiency, our knowledge about the relevance of plasma PLTP activity for human lipid metabolism is still incomplete. No investigational drugs are available that specifically target the activity of this protein. 

A molecular variation of plasma membrane has been reported by Puccia et al. Reduction of total lipids (XL) content and significant variations of triglyceride (TG) and phospholipids (PL) fractions were observed as a consequence of exposure of C. intestinalis ovaries to TBTCl solutions. In particular, an evident TG decrease and a PL increase were observed, which probably provoked an increment in membrane fluidity, because of the high concentration of long chain fatty acids and, as a consequence, PL. This could be a cell-adaptive standing mechanism toward the pollutants, as observed in Saccharomyces cerevisiae. Also the increase in the content of the polyunsaturated fatty acids (PUPA), important in the synthesis of compounds such as prostaglandin which are present in the ovary in a stress situation, was probably a consequence of a defense mechanism to the stress provoked by the presence of TBTCl. 

The diversity in primary, secondary, tertiary, and quaternary stmctures of proteins means that few generalisations can be made concerning their chemical properties. Some fulfil stmctural roles, such as the collagens (found in bone) and keratin (found in claws and beaks), and are insoluble in all solvents. Others, such as albumins or globulins of plasma, are very soluble in water. Still others, which form part of membranes of cells, are partly hydrophilic ( water-loving , hence water-soluble) and partly lipophilic ( lipid-loving , hence fat-soluble). 

The second type of fatty liver is usually due to a metabolic block in the production of plasma lipoproteins, thus allowing triacylglycerol to accumulate. Theoretically, the lesion may be due to (1) a block in apolipoprotein synthesis, (2) a block in the synthesis of the lipoprotein from lipid and apolipoprotein, (3) a failure in provision of phospholipids that are found in lipoproteins, or (4) a failure in the secretory mechanism itself. 

Rye K-A et al Overview of plasma lipid transport. In Plasma Lipids and Their Role in Disease. Barter PJ, Rye K-A (editors). Harwood Academic Publishers, 1999. 

Nowadays, consumers would like those antioxidants present in food products not only to stabilise food lipids, but also to be absorbed through the intestinal wall and protect the lipids of blood plasma against oxidation. This effect is relatively evident in the case of tocopherols (which are liposoluble) or ascorbic acid (which is hydrophilic), but much less evidence is available on antioxidants of medium polarity, such as flavonoids, rosemary oleoresins or green or black tea catechins. 

Kayden, H.J. andTraber, M.G. (1993). Absorption, lipoprotein transport and regulation of plasma concentrations of vitamin E in humans. J. Lipid Res. 34, 343-358. 

Lipid peroxidation is a radical-mediated chain reaction resulting in the degradation of polyunsaturated fatty acids (PUFAs) that contain more than two covalent carbon-carbon double bonds (reviewed by Esterbauer et al., 1992). One of the major carriers of plasma lipids is LDL, a spherical molecule with a molecular weight of 2.5x10 . A single LDL particle contains 1300 PUFA molecules (2700 total fatty-acid molecules) and is... 

Delivery systems for gene-based drugs are needed to fulfill their promise in the medical treatment. Interactions of the potential delivery systems with the lipid bilayers are of crucial importance, since the lipid bilayer barrier must be overcome either at the level of plasma membrane or in the endosomes. 

Han KH, Han KO, Green SR, Quehenberger O. Expression of the monocyte chemoattractant protein-1 receptor CCR2 is increased in hypercholesterolemia. Differential effects of plasma lipoproteins on monocyte function. J Lipid Res 1999 40(6) 1053-1063. 

Hyperlipemia may manifest itself by an increased concentration of lipids, or certain groups thereof. For example, hypercholesterolemia and hypertriglyceri-demia may be mentioned in this connection. Since practically all the blood plasma lipids make part of lipoproteins, hyperlipemias may be reduced to one of the hyper-lipoproteinemia forms which differ in the varied ratios of plasma lipoproteins of different groups. 

Lipid extraction 200 pL of plasma sample is mixed by brief vortexing with 200 pL of ethanol followed 1 min of vortexing with 800 pL hexane. After centrifugation for 5 min at 5000 rpm, 400 pL of upper (hexane) phase is transferred to a glass tube with screwed cap, dried under nitrogen, and kept at - 60°C until PCL analysis. For PCL analysis the sample is dissolved in 400 pL of MeOH by 30 s of vortexing, and 100 pL aliquots are taken for ACL assay. 

The lipid compositions of plasma membranes, endoplasmic reticulum and Golgi membranes are distinct 26 Cholesterol transport and regulation in the central nervous system is distinct from that of peripheral tissues 26 In adult brain most cholesterol synthesis occurs in astrocytes 26 The astrocytic cholesterol supply to neurons is important for neuronal development and remodeling 27 The structure and roles of membrane microdomains (rafts) in cell membranes are under intensive study but many aspects are still unresolved 28... 

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