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BIOACTIVE LIPIDS

Lipid phosphate phosphohydrolases (LPPs), formerly called type 2 phosphatidate phosphohydrolases (PAP-2), catalyse the dephosphorylation of bioactive phospholipids (phosphatidic acid, ceramide-1-phosphate) and lysophospholipids (lysophosphatidic acid, sphingosine-1-phosphate). The substrate selectivity of individual LPPs is broad in contrast to the related sphingosine-1-phosphate phosphatase. LPPs are characterized by a lack of requirement for Mg2+ and insensitivity to N-ethylmaleimide. Three subtypes (LPP-1, LPP-2, LPP-3) have been identified in mammals. These enzymes have six putative transmembrane domains and three highly conserved domains that are characteristic of a phosphatase superfamily. Whether LPPs cleave extracellular mediators or rather have an influence on intracellular lipid phosphate concentrations is still a matter of debate. [Pg.693]

Tesoriere, L. et ah. Biothiols, taurine, and lipid-soluble antioxidants in the edible pulp of Sicilian cactus pear (Opuntia ficus-indica) fruits and changes of bioactive juice components upon industrial processing, J. Agric. Food Chem., 53, 7851, 2005. [Pg.295]

Transferosomes represent another system of encapsulation using ultradeformable vesicle carriers for bioactive molecules, applied until now for direct transdermal drug delivery. They are built from polar lipids and have high flexibility, and are rich in unsaturated fatty acids and carotenoid pigments." ... [Pg.320]

Dynamic aspects of drugs delivered into lipid bilayer membranes are significant in discussing bioactivities and the mechanism of the drug-membrane interactions. So far, however, the dynamic properties of drugs in the membrane interior have not been well understood. No systematic NMR experiments have been carried out because of the low concentration of the bilayer interior. In this section, we illustrate how to obtain dynamic features of drug molecules trapped in membranes by NMR. [Pg.786]

Although the drug delivery to the lipid bilayer membrane is just the first step for bioactivities and phopholipid vesicles are rather simple in view of the composite structure of biomembranes, the unambiguous specification of the preferential location of the drug is essential the successive processes of the action are expected to be induced via the delivery site in membranes. We expect more advances in the dynamic NMR study, so that we can get insight into the mechanism of DD in membranes. [Pg.799]

Possible Mechanism of Allelopathlc Action of Water-Insoluble Plant Lipids. Many non-polar natural products with germination and growth regulation activities In laboratory tests are In pure form not sufficiently water soluble to account for their allelopathlc activities observed In the field. For this reason the notion exists that sterols and other non-polar plant constituents are not likely to play a role In allelopathlc actions, and It Is generally concluded that the bioactivity data observed In the laboratory are therefore coincidental. [Pg.146]

Bioactive peptides such as superoxide dismutase and interferon arc also hoped to be accumulated in the inflamed and vascular lesions. However, these active peptides cannot be incorporated in lipid microspheres. Instead of incorporating them into lipid microspheres, we devised a method to combine the bioactive peptides with a chemically modified lecithin. In this study, we also examined the tissue distribution of lecithinized IgG. [Pg.265]

Mayer, L. D. Bally, M. B. Hope, M. J. Cullis, P R., Techniques for encapsulating bioactive agents into liposomes, Chem. Phys. Lipids 40, 333-345 (1986). [Pg.272]

Volume 432. Lipidomics and Bioactive Lipids Mass-Spectrometry—Based Lipid Analysis (in preparation)... [Pg.37]

Olbrich, C., Kayser, O., Muller, R.H., and Grubhofer, N., Solid lipid nanoparticles (SLN) as vaccine adjuvant study in sheep with a mycoplasma bovis antigen and stability testing, International Symposium of Controlled Release and Bioactive Material, 2000, 27, 293-294. [Pg.16]

Several enveloped viruses, and some physical gene transfer techniques such as electroporation, deliver the nucleic acid into the cell by direct crossing of the cell membrane. Lipid-based, enveloped systems can do this by a physiological, selfsealing membrane fusion process, avoiding physical damage of the cell membrane. For cationic lipid-mediated delivery of siRNA, most material is taken up by endo-cytotic processes. Recently, direct transfer into the cytosol has been demonstrated to be the bioactive delivery principle for certain siRNA lipid formulations [151]. [Pg.8]

Other systems like electroporation have no lipids that might help in membrane sealing or fusion for direct transfer of the nucleic acid across membranes they have to generate transient pores, a process where efficiency is usually directly correlated with membrane destruction and cytotoxicity. Alternatively, like for the majority of polymer-based polyplexes, cellular uptake proceeds by clathrin- or caveolin-dependent and related endocytic pathways [152-156]. The polyplexes end up inside endosomes, and the membrane disruption happens in intracellular vesicles. It is noteworthy that several observed uptake processes may not be functional in delivery of bioactive material. Subsequent intracellular obstacles may render a specific pathway into a dead end [151, 154, 156]. With time, endosomal vesicles become slightly acidic (pH 5-6) and finally fuse with and mature into lysosomes. Therefore, polyplexes have to escape into the cytosol to avoid the nucleic acid-degrading lysosomal environment, and to deliver the therapeutic nucleic acid to the active site. Either the carrier polymer or a conjugated endosomolytic domain has to mediate this process [157], which involves local lipid membrane perturbation. Such a lipid membrane interaction could be a toxic event if occurring at the cell surface or mitochondrial membrane. Thus, polymers that show an endosome-specific membrane activity are favorable. [Pg.8]

Surfactant has a similar amphoteric structure as lipid, which makes it possible to form a stable membrane the same as a lipid membrane and can be used to embed proteins. A surfactant membrane has many characteristics similar to those of a biomembrane, so that it can retain the bioactivities of proteins well. The process of preparing a sur-factant/protein-modified electrode is simple and viable. There are usually two methods... [Pg.557]

LOX-catalyzed oxidation of LDL has been studied in subsequent studies [26,27]. Belkner et al. [27] showed that LOX-catalyzed LDL oxidation was not restricted to the oxidation of lipids but also resulted in the cooxidative modification of apoproteins. It is known that LOX-catalyzed LDL oxidation is regio- and enantio-specific as opposed to free radical-mediated lipid peroxidation. In accord with this proposal Yamashita et al. [28] showed that LDL oxidation by 15-LOX from rabbit reticulocytes formed hydroperoxides of phosphatidylcholine and cholesteryl esters regio-, stereo-, and enantio-specifically. Sigari et al. [29] demonstrated that fibroblasts with overexpressed 15-LOX produced bioactive minimally modified LDL, which is probably responsible for LDL atherogenic effect in vivo. Ezaki et al. [30] found that the incubation of LDL with 15-LOX-overexpressed fibroblasts resulted in a sharp increase in the cholesteryl ester hydroperoxide level and a lesser increase in free fatty acid hydroperoxides. [Pg.809]

Excitable membranes maintain and rapidly modulate substantial transmembrane ion gradients in response to stimuli 576 Specific lipid messengers are cleaved from reservoir phospholipids by phospholipases upon activation by various stimuli 576 Phospholipids in synaptic membranes are an important target in seizures, head injury, neurodegenerative diseases and cerebral ischemia 576 Some molecular species of phospholipids in excitable membranes are reservoirs of bioactive lipids that act as messengers 576 Mammalian phospholipids generally contain polyunsaturated fatty acyl chains almost exclusively esterified to the second carbon of glycerol 577... [Pg.575]

This chapter surveys the neurochemistry of lipid messengers, as well as the mechanisms by which bioactive lipids accumulate upon stimulation in response to injury, cerebral ischemia, seizures, neurotrauma or neurodegen-erative diseases, and their significance in pathophysiology. Emphasis is placed on three groups of bioactive lipids AA and its metabolites, known collectively as eicosanoids PAF, a highly potent ether phospholipid and the newly identified DHA-derived mediator, neuroprotectin Dl. [Pg.577]

AA metabolites and PAF have initially been studied in terms of their roles in the inflammatory response, such as increased vascular permeability and the activation of and infiltration by inflammatory cells. It is now becoming apparent, however, that these bioactive lipids have significant neurobiological actions in ion channel functions, receptors, neurotransmitter release, synaptic plasticity and neuronal gene expression. [Pg.577]

Moreover,bioactive lipids maybe considered dual messengers they modulate cell functions as messengers and they become part of the response of the nervous tissue to injury, broadly referred to as the inflammatory response. This response occurs in ischemia-reperfusion damage associated with stroke, various forms of neurotrauma, infectious diseases and neurodegenerative diseases such as Alzheimer s disease. Inflammation in the nervous system differs from that in other tissues. If the blood-brain barrier is broken, blood-borne inflammatory cells (e.g. polymorphonuclear leukocytes, monocytes, macrophages) invade the intercellular space and glial cells are activated, particularly microglia, which play a prominent role in the inflammatory response. These responses may... [Pg.577]

Phospholipid molecules of membranes from neurons and glial cells store a wide variety of lipid messengers. Receptor-mediated events and changes in [Ca2+]i, such as occur during excitatory neurotransmission and activity-depen-dent synaptic plasticity, activate phospholipases that catalyze the release of bioactive moieties from phospholipids, which then participate in intra- and/or intercellular signaling pathways. [Pg.579]


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See also in sourсe #XX -- [ Pg.576 ]




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