Lipid metabolism and transport

The normal function of lipoproteins is to distribute and recycle cholesterol. The pathways of lipid metabolism and transport and their primary (inherited) disorders appear in Figure 25.1 and can be summarised thus ... 

Robertson AF. Sprecher H. A review of human placental lipid metabolism and transport. Acta Paediatr Scand 1968 183(Suppl) 2-18. 

As the RPE plays an important role in lipid metabolism and regulation of dynamic transport between the choriocapillaris and photoreceptors, it is important to determine whether carotenoids affect these pathways in the RPE. 

LBPs are likely to have conventional roles in the energy metabolism and transport of lipids in nematodes for membrane construction, etc. Many parasitic helminths have deficiencies in the synthesis of some lipids and so their lipid acquisition, transport and storage mechanisms clearly need to be specialized and therefore pertinent to the host-parasite relationship (Barrett, 1981). From a practical point of view, lipid transporter proteins may also be important in the delivery of anthelmintic drugs to their target most anthelmintics are hydrophobic and if they do not distribute to their site of action within the parasites by simple diffusion across and along membranes, then the parasite s own carrier proteins may be involved. 

Cholesterol is present in all animal tissues, and particularly in neural tissue. It is a major constituent of cellular membranes, in which it regulates fluidity (see p. 216). The storage and transport forms of cholesterol are its esters with fatty acids. In lipoproteins, cholesterol and its fatty acid esters are associated with other lipids (see p.278). Cholesterol is a constituent of the bile and is therefore found in many gallstones. Its biosynthesis, metabolism, and transport are discussed elsewhere (see pp. 172, 312). 

One of the major obstacles to definitively examining the role of formulation components on enterocyte-based processes is the possible effect of excipient inclusion on other complicating factors. For example, the inclusion of lipids or surfactants in in vitro metabolic or transport screens runs the risk of affecting the thermodynamic activity of the drug in solution, thereby obscuring the role of metabolic and transport processes. Similarly, some surfactants and lipid-surfactant conjugates may cause transient increases in intestinal permeability as... 

The lipidome profile of mice liver homogenates of free cholesterol, low cholesterol, and high cholesterol diets showed the influence between dietary cholesterol intake and atherosclerosis (17). To get individual metabolite fingerprints, they measured near 300 metabolites such as di- and triglycerides, phosphatidylcholines, LPCs, and cholesterol esters in plasma samples by LC-MS/MS. It was observed that when dietary cholesterol intake was increased, the liver compensated for elevations in plasma cholesterol by adjusting metabolic and transport processes related to lipid metabolism, which... 

Pfeffer, P. E., Douds, D. D., Becard, G. Shachar-Hill, Y. (1999). Carbon uptake and the metabolism and transport of lipids in an arbuscular mycorrhiza. Plant Physiology,... 

The character of HDL in cord blood is distinct from adult blood. Eetal HDL is apolipoprotein E-rich, with much lower esterified cholesterol. HDL represents fhe major lipoprotein class in cord blood, a marked change from the adult plasma h-poprotein profile. The phosphohpid content was the same as the HDL of adults [13]. A plausible hypothesis is fhat EL is directly involved in lipid metabolism and cholesterol transport in the developing fetus. 

In order to carry out PHA production from triglycerides, the cells need to hydrolyze the triglycerides into free fatty acids that can be transported into the cells. For this, the cells need to secrete an enzyme called lipase. A wide variety of organisms is known to secrete lipolytic enzymes, mainly for lipid metabolism and signal transduction. Lipolytic enzymes can be classified into different classes, including lipases, esterases, and phospholipases (Arpigny and Jaeger 1999). Esterases are enzymes that hydrolyze ester bonds of soluble or partially soluble molecules. 

The entry of many orally administered drugs into the systemic circulation is dependent on their tendency to partition into lipid (lipophilicity). Lipophilic properties facilitate a compound s penetration of lipid membranes and transportation in blood lipoproteins but their lower water solubility reduces urinary excretion. In addition, lipophilic compounds are more likely to undergo extensive metabolism. 

Fatty acid transport proteins (FATPs) are an evolutionary conserved family of integral membrane proteins found at the plasma membrane and on internal membranes. FATPs facilitate the unidirectional uptake and/ or intracellular activation of unesterified long-chain and very long-chain fatty acids (LCFAs) into a variety of lipid-metabolizing cells and tissues. 

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