Lipid, lung surfactant

Beneficial effects have also been attributed to PAF. In reproduction, PAF secreted by the fertilized egg is instrumental in the implantation of the egg in the uterine wall. PAF is produced in significant quantities in the lungs of the fetus late in pregnancy and may stimulate the production of fetal lung surfactant, a protein-lipid complex that prevents collapse of the lungs in a newborn infant. 

Lung surfactant is composed mainly of lipid with some proteins and carbohydrate and prevents the alveoli from collapsing. Surfactant activity is largely attributed to dipalmitoylphosphatidylcholine, which is synthesized shortly before parturition in full-term infants. Deficiency of lung surfactant in the lungs of many preterm newborns gives rise to respiratory distress syndrome. Administration of either natural or artificial surfactant has been of therapeutic benefit. 

Oosterlaken-Dijksterhuis MA, Haagsman HP, van Golde LM, et al. Characterization of lipid insertion into monomolecular layers mediated by lung surfactant proteins SP-B and SP-C. Biochemistry 1991 30(45) 10965-10971. 

Lung surfactant is a mixture of proteins and amphipathic lipids that acts like a detergent or soap to greatly decrease the surface tension forces at the alveolar fluid-air interface. 

Most materials used to produce liposomes are derived from natural materials, thus are thought to be safe when administered. Generally, however, phospholipids administered in liposomal form are cleared from the lungs more slowly than comparable doses of lung surfactant (Oguchi et al. 1985). Many macromolecules have been incorporated into liposomes in order to improve their pulmonary delivery. Some lipid-entrapped macromolecules have been tested in animal models and human volunteers to determine efficacy (Kellaway and Farr 1990). 

Functions of the phospholipid Phospholipids are the predominant lipids of cell membranes. They also function as a reservoir of intracellular messengers and as anchors for some proteins to cell membranes. Non-membrane-bound phospholipids serve as components of lung surfactant and bile. 

Phospholipid that is the major component of Tung surfactant, and the syndrome caused by its deficiency Dipalmitoylphosphatidylcholine (DPPC, also called dipalmitoyllecithin, DPPL) is the major lipid component of lung surfactant. It is made and secreted by type II granular pneu-mocytes. Insufficient surfactant production causes respiratory distress syndrome, which can occur in preterm infants or adults whose surfactant-producing pneumocytes have been damaged or destroyed. 

With the objective of designing new compositions of synthetic substitutes for the native lung surfactant, it is desirable to control the physical state and properties of dipalmitoylphosphatidylcholine (DPPC) spread at the air/water interface. DPPC is the main component of the native lung surfactant, which also comprises a complex mixture of lipids and specific proteins [62], Langmuir monolayers provide a model of the air/alveolar interface that is widely used for assessing the properties of lung surfactant replacement compositions. 

A lipid found in brain, blood cells and lung surfactant. 

DPPC is prominent in the lipid bilayer making up the cell membrane and is also a major constituent of lung surfactant ( pulmonary surfactant). The lung membrane resembles a mixed surfactant monolayer at the air/water interface. Since the temperature in a lung is below the critical temperature for DPPC monolayers, the LE-LC transition may be of significance in the continuous compression and expansion loops that this membrane undergoes during respiration. We will say more about this in sec. 3.9. 

The action of lipid-protein mixtures, mimicking those of physiological lung surfactants can be, and has been, studied in Langmuir troughs. For instance, in one of such studies the monolayers were subjected to compression-expansion cycles. At... 

Surfacten (Surfactant-TA) 100/4 Minced cow lung extract -h synthetic lipids Lung lipids + DPPC, tripalmitin, palmitic acid 30 100... 

See also Molecular Structures and Properties of Lipids, Phosphatidic Acid, Cardiolipin, Phosphatidylserine, Phosphatidylethanolamine, Phosphatidylglycerol, Phosphatidylcholine, CDP-Diacylglycerol, Phosphatidylglycerol-3-Phosphate, Phosphatidylinositol, Lung Surfactant, Sphingolipids, Glycosphingolipids,... 

A prime example is the phospholipid component of lung surfactant, a lipid- and protein-containing substance that is secreted from lung and prevents collapse of the alveoli when air is expelled. Lung surfactant contains 50-60% dipalmitoylphosphatidylcholine, a saturated glycerophospholipid. Normally, about 90% of the fatty acids at position two for glycerophospholipids are unsaturated. 

Lung lipids and cytotoxic dusts, 552 Lung surfactant, see Pulmonary surfactant Luteol dipalmitate, 38 Lycopodium complanatum, 19 Lye, 240... 

Saleem, M., Galla, H.-J. (2010) Surface view of the lateral organization of lipids and proteins in lung surfactant model systems—A ToF-SIMS approach. Biochim. Biophys. Acta, 1798,730-740. 

Protein and lipid interactions in lung surfactant monolayers... 

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