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D. Julian Mcclements – One of the best experts on this subject based on the ideXlab platform.

  • Mechanisms of Lipid oxidation in food dispersions
    Trends in Food Science and Technology, 2011
    Co-Authors: Thaddao Waraho, D. Julian Mcclements, Eric Andrew Decker
    Abstract:

    As the continues to improve the nutritional content of their products, challenges in prevention of rancidity have increased due to the presence of more polyunsaturated fattfatty acids. In addition, consumer demand for all natural foods has limited the use of traditional methods to control Lipid oxidation such as synthetic antioxidants and hydrogenation. To overcome these challenges a better understand the mechanisms of Lipid oxidation are needed so that novel antioxidant technologies can be developed. Lipids in foods often exist as dispersions stabilized by emulsifiers that provide physical stability. Food emulsions contain an oil-water interface that has major impact on the Lipid oxidation pathways by influencing the location and reactivity of prooxidative transition metals, Lipid hydroperoxides, minor Lipid components, free radical scavengers and metal chelators. Understanding how the physical properties of the Lipid-water or Lipid-air interface in food dispersions impacts oxidation chemistry has lead to new strategies to create Lipid structures that slow down the development of rancidity by decreasing interaction between Lipids in the emulsion droplet core with prooxidants and oxygen as well as increasing antioxidant concentrations at the site of oxidation. ?? 2010 Elsevier Ltd.

  • Lipid oxidation in food emulsions
    Trends in Food Science and Technology, 1996
    Co-Authors: John N. Coupland, D. Julian Mcclements
    Abstract:

    Lipid oxidation is a major cause of quality deterioration in food emulsions. The design of foods with improved quality depends on a better understanding of the physicochemical mechanisms of Lipid oxidation in these systems. The oxidation of emulsified Lipids differs from that of bulk Lipids, because of the presence of the droplet membrane, the interactions between the ingredients, and the partitioning of ingredients between the oil, aqueous and interfacial regions. ©1996, Elsevier Science Ltd.

Rainer H. Müller – One of the best experts on this subject based on the ideXlab platform.

  • solid Lipid nanoparticles for parenteral drug delivery
    Advanced Drug Delivery Reviews, 2004
    Co-Authors: S A Wissing, Oliver Kayser, Rainer H. Müller
    Abstract:

    Abstract This review describes the use of nanoparticles based on solid Lipids for the parenteral application of drugs. Firstly, different types of nanoparticles based on solid Lipids such as “solid Lipid nanoparticles” (SLN), “nanostructured Lipid carriers” (NLC) and “Lipid drug conjugate” (LDC) nanoparticles are introduced and structural differences are pointed out. Different production methods including the suitability for large scale production are described. Stability issues and drug incorporation mechanisms into the particles are discussed. In the second part, the biological activity of parenterally applied SLN and biopharmaceutical aspects such as pharmacokinetic profiles as well as toxicity aspects are reviewed.

  • Effect of cationic Lipid and matrix Lipid composition on solid Lipid nanoparticle-mediated gene transfer
    European Journal of Pharmaceutics and Biopharmaceutics, 2004
    Co-Authors: Kerstin Tabatt, Mohammad Sameti, Carsten Olbrich, Rainer H. Müller, Claus-michael Lehr
    Abstract:

    This investigation is focused on the enhancement of in vitro transfection activity by optimizing cationic Lipid and matrix Lipid composition of solid Lipid nanoparticles (SLN). For this purpose SLN were formulated by using two different matrix Lipids and six different cationic detergents. These 12 formulations were tested for physical parameters such as particle size, zeta potential and DNA-binding capacity, and also for their biological properties such as cytotoxicity and in vitro transfection efficiency. The SLN were produced by hot high-pressure homogenization, all formulations were physically stable and showed a highly positive surface charge (+34 to +45 mV). In vitro cytotoxicity measurements on COS-1 cells revealed that cytotoxicity is strongly dependent on the cationic Lipid used. SLN made from one-tailed cationic detergents were highly cytotoxic. In contrast the two-tailed cationic Lipids were all well tolerated. Transfection activity seems to be determined by both the cationic Lipid and the matrix Lipid used. Here, the combination of cetylpalmitate and N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium chloride led to significantly higher transfection efficiencies than in all other tested combinations. These results indicate that well tolerated and highly efficient in vitro transfection could be achieved with SLN whenever selecting good combinations of two-tailed cationic Lipids and matrix Lipids.

Tibor Páli – One of the best experts on this subject based on the ideXlab platform.

  • Orientation and conformation of Lipids in crystals of transmembrane proteins
    European Biophysics Journal, 2013
    Co-Authors: Derek Marsh, Tibor Páli
    Abstract:

    Orientational order parameters and individual dihedral torsion angles are evaluated for phosphoLipid and glycoLipid molecules that are resolved in X-ray structures of integral transmembrane proteins in crystals. The order parameters of the Lipid chains and glycerol backbones in protein crystals are characterised by a much wider distribution of orientational order than is found in fluid Lipid bilayers and reconstituted Lipidprotein membranes. This indicates that the Lipids that are resolved in crystals of membrane proteins are mostly not representative of the entire Lipidprotein interface. Much of the chain configurational disorder of the membrane-bound Lipids in crystals arises from C-C bonds in energetically disallowed skew conformations. This suggests configurational heterogeneity of the Lipids at a single binding site: eclipsed conformations occur also in the glycerol backbone torsion angles and the C-C torsion angles of the Lipid head groups. Conformations of the Lipid glycerol backbone in protein crystals are not restricted to the gauche C1-C2 rotamers found invariably in phosphoLipid bilayer crystals. Lipid head-group conformations in the protein crystals also do not conform solely to the bent-down conformation, with gauche-gauche configuration of the phosphodiester, that is characteristic of phosphoLipid bilayer membranes. Stereochemical violations in the protein-bound Lipids are evidenced by ester carboxyl groups in non-planar configurations, and even in the cis configuration. Some Lipids have the incorrect enantiomeric configuration of the glycerol backbone, and many of the branched methyl groups in the phytanyl chains associated with bacteriorhodopsin have the incorrect S configuration.

  • Lipid conformation in crystalline bilayers and in crystals of transmembrane proteins
    Chemistry and Physics of Lipids, 2006
    Co-Authors: Derek Marsh, Tibor Páli
    Abstract:

    Dihedral torsion angles evaluated for the phosphoLipid molecules resolved in the X-ray structures of transmembrane proteins in crystals are compared with those of phosphoLipids in bilayer crystals, and with the phosphoLipid conformations in fluid membranes. Conformations of the Lipid glycerol backbone in protein crystals are not restricted to the gauche C1-C2 rotamers found invariably in phosphoLipid bilayer crystals. Lipid headgroup conformations in protein crystals also do not conform solely to the bent-down conformation, with gauche-gauche configuration of the phospho-diester, that is characteristic of phosphoLipid bilayer membranes. This suggests that the Lipids that are resolved in crystals of membrane proteins are not representative of the entire Lipidprotein interface. Much of the chain configurational disorder of the membrane-bound Lipids in crystals arises from energetically disallowed skew conformations. This indicates a configurational heterogeneity in the Lipids at a single binding site: eclipsed conformations occur also in some glycerol backbone torsion angles and C-C torsion angles in the Lipid headgroups. Stereochemical violations in the protein-bound Lipids are evidenced by one-third of the ester carboxyl groups in non-planar configurations, and certain of the carboxyls in the cis configuration. Some of the Lipid structures in protein crystals have the incorrect enantiomeric configuration of the glycerol backbone, and many of the branched methyl groups in structures of the phytanyl chains associated with bacteriorhodopsin crystals are in the incorrect S-configuration. © 2006 Elsevier Ireland Ltd. All rights reserved.

Eric Andrew Decker – One of the best experts on this subject based on the ideXlab platform.

  • Mechanisms of Lipid oxidation in food dispersions
    Trends in Food Science and Technology, 2011
    Co-Authors: Thaddao Waraho, D. Julian Mcclements, Eric Andrew Decker
    Abstract:

    As the continues to improve the nutritional content of their products, challenges in prevention of rancidity have increased due to the presence of more polyunsaturated fatty acids. In addition, consumer demand for all natural foods has limited the use of traditional methods to control Lipid oxidation such as synthetic antioxidants and hydrogenation. To overcome these challenges a better understand the mechanisms of Lipid oxidation are needed so that novel antioxidant technologies can be developed. Lipids in foods often exist as dispersions stabilized by emulsifiers that provide physical stability. Food emulsions contain an oil-water interface that has major impact on the Lipid oxidation pathways by influencing the location and reactivity of prooxidative transition metals, Lipid hydroperoxides, minor Lipid components, free radical scavengers and metal chelators. Understanding how the physical properties of the Lipid-water or Lipid-air interface in food dispersions impacts oxidation chemistry has lead to new strategies to create Lipid structures that slow down the development of rancidity by decreasing interaction between Lipids in the emulsion droplet core with prooxidants and oxygen as well as increasing antioxidant concentrations at the site of oxidation. ?? 2010 Elsevier Ltd.

  • Lipid Oxidation in Oil-in-Water Emulsions: Impact of Molecular Environment on Chemical Reactions in Heterogeneous Food Systems
    Journal of Food Science, 2000
    Co-Authors: David Julian Mcclements, Eric Andrew Decker
    Abstract:

    The susceptibility of Lipids to oxidation is a major cause of quality deterioration in food emulsions. The reaction mechanism and factors that influence oxidation are appreciably different for emulsified Lipids than for bulk Lipids. This article reviews the current understanding of the Lipid oxidation mechanism in oil-in-water emulsions. It also discusses the major factors that influence the rate of Lipid oxidation in emulsions, such as antioxidants, chelating agents, ingredient purity, ingredient partitioning, interfacial characteristics, droplet characteristics, and ingredient interactions. This knowledge is then used to define effective strategies for controlling Lipid oxidation in food emulsions.

Marine Froissard – One of the best experts on this subject based on the ideXlab platform.

  • Single cell synchrotron FT-IR microspectroscopy reveals a link between neutral Lipid and storage carbohydrate fluxes in S. cerevisiae.
    PloS one, 2013
    Co-Authors: Frédéric Jamme, Thierry Chardot, Jean David Vindigni, Valérie Méchin, Tamazight Cherifi, Marine Froissard
    Abstract:

    In most organisms, storage Lipids are packaged into specialized structures called Lipid droplets. These contain a core of neutral Lipids surrounded by a monolayer of phosphoLipids, and various proteins which vary depending on the species. Hydrophobic structural protproteins stabilize the interface between the Lipid core and aqueous cellular environment (perilipin family of proteins, apolipoproteins, oleosins). We developed a genetic approach using heterologous expression in Saccharomyces cerevisiae of the Arabidopsis thaliana Lipid droplet oleosin and caleosin proteins AtOle1 and AtClo1. These transformed yeasts overaccumulate Lipid droplets, leading to a specific increase in storage Lipids. The phenotype of these cells was explored using synchrotron FT-IR microspectroscopy to investigate the dynamics of Lipid storage and cellular carbon fluxes reflected as changes in spectral fingerprints. Multivariate statistical analysis of the data showed a clear effect on storage carbohydrates and more specifically, a decrease in glycogen in our modified strains. These observations were confirmed by biochemical quantification of the storage carbohydrates glycogen and trehalose. Our results demonstrate that neutral Lipid and storage carbohydrate fluxes are tightly connected and co-regulated.

  • Heterologous expression of AtClo1, a plant oil body protein, induces Lipid accumulation in yeast
    FEMS Yeast Research, 2009
    Co-Authors: Marine Froissard, Sabine D'Andréa, Sabine D'andréa, Céline Boulard, Thierry Chardot
    Abstract:

    Proteomic approaches on Lipid bodies have led to the identification of proteins associated with this compartment, showing that, rather than the inert fat depot, Lipid droplets appear as complex dynamic organelles with roles in metabolism control and cell signaling. We focused our investigations on caleosin [Arabidopsis thaliana caleosin 1 (AtClo1)], a minor protein of the Arabidopsis thaliana seed Lipid body. AtClo1 shares an original triblock structure, which confers to the protein the capacity to insert at the Lipid body surface. In addition, AtClo1 possesses a calcium-binding domain. The study of plants deficient in caleosin revealed its involvement in storage Lipid degradation during seed germgermination. Using Saccharomyces cerevisiae as a heterologous expression system, we investigated the potential role of AtClo1 in Lipid body biogenesis and filling. The green fluorescent protein-tagged protein was correctly targeted to Lipid bodies. We observed an increase in the number and size of Lipid bodies. Moreover, transformed yeasts accumulated more fatty acids (+46.6%). We confirmed that this excess of fatty acids was due to overaccumulation of Lipid body neutral Lipids, triacylglycerols and steryl esters. We showed that the original intrinsic properties of AtClo1 protein were sufficient to generate a functional Lipid body membrane and to promote overaccumulation of storage Lipids in yeast oil bodies.