Dissertations / Theses on the topic 'Lipids'
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1
Kotland, Vojtěch. "Separace lipidů z buněčných tkání." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2019. http://www.nusl.cz/ntk/nusl-401857.
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This master’s thesis is focused on lipid separation from tissue cells. Thesis is divided into theoretical and experimental part. In the theoretical part is summarized current knowledge about lipids, their properties and methods used to separate them from tissue cells. Those methods were compared and one of them was chosen to be used in the experimental part. Theoretical part is ended with reviews aimed towards the research in this area of chemistry. Experimental part describes factors affecting chosen method of lipid separation from tissue cells. The measurements were chosen so that they could be easily reproduced. Values for each factor were experimentally determined to increase the amount of fat separated. All factors were compared and based on their summarization the optimization for whole method was produced.
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Cvrková, Jana. "Stanovení lipidů a zastoupení mastných kyselin v obilce ječmene." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2010. http://www.nusl.cz/ntk/nusl-216627.
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The diploma thesis deals with the determination of lipids and fatty acid profile in a barley caryopsis.(Hordeum vulgare). The theoretical part describes the synthesis of fatty acids and their degradation in plant material, secondly, it described the possibilities of lipid extraction and their determination and the possibilities of determination of fatty acids. In the experimental part method of lipid extraction on automated extractor Fex ®IKA and determination of fatty acids by GC-FID were optimized. For analysis of fatty acids two capillary columns SLB-IL 100 and Supelcowax were compared. Twenty varieties of barley from the year 2008 and twenty varieties from the year 2009 were compared based on the content of lipids and the representation of fatty acids in a barley caryopsis. The diploma thesis was realized in the Research Institute of Brewing and Malting, Plc. in Brno.
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Mateos, Diaz Eduardo. "Etude par spectroscopie infrarouge (FTIR) des interactions de la lipase pancréatique apparentée de type 2 (PLRP2) avec les phospholipides et les sels biliaires." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4763.
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La lipase pancréatique apparentée de type 2 du cobaye (GPLRP2) hydrolyse une grande variété de substrats lipidiques. Elle montre cependant une sélectivité selon l’organisation supramoléculaire du substrat et la présence de surfactants comme les sels biliaires (NaTDC). Nous avons utilisé la spectroscopie infrarouge (FTIR) pour étudier les interactions entres les phospholipides (DPPC), les surfactants et la GPLRP2 dans des conditions expérimentales proches de celles du tractus digestif. Pour étudier l’étape d’adsorption indépendamment de l’hydrolyse, un variant inactif de GPLRP2 (S152G) a été produit. Diverses dispersions aqueuses de phospholipides ont été préparées : des vésicules multilamellaires (MLV), unilamellaires (LUV) et des micelles mixtes DPPC-surfactant. GPLRP2 hydrolyse le DPPC présent dans des micelles mixtes DPPC-NaTDC mais n’a aucune activité sur le DPPC en phase lamellaire ou présent dans des micelles DPPC-Triton X100. L’analyse par FTIR de l’interaction de GPLRP2 S152G avec le système DPPC-NaTDC montre des changements importants dans le désordre conformationnel et la mobilité des chaînes acyles, la déshydratation de l’interface, l’orientation des têtes polaires et leurs liaisons hydrogène. Aucun effet n’est observé avec les MLV, les LUV ou le système DPPC-Triton X100. Il y a ainsi une reconnaissance spécifique du DPPC dans les micelles mixtes avec les sels biliaires, en accord avec l’activité enzymatique de GPLRP2. Les changements du spectre IR pendant l’hydrolyse du DPPC par la GPLRP2 ont été suivis. Certaines caractéristiques attribuées à la formation de produits de lipolyse peuvent être utilisées pour une étude quantitative de la lipolyse par FTIRGuinea pig pancreatic lipase-related protein type 2 (GPLRP2) hydrolyzes a large set of lipid substrates, but displays however some selectivity depending on the supramolecular structure of substrate and the presence of surfactants like bile salts (NaTDC). We used Fourier transform infrared (FTIR) spectroscopy to study the interactions between phospholipids (DPPC), surfactants and GPLRP2 under conditions close to those of the GI tract. To study the adsorption step independently from hydrolysis, a GPLRP2 inactive variant (S152G) was produced. Various phospholipid dispersions were prepared: multilamellar (MLV) and large unilamellar vesicles (LUV) and mixed micelles with surfactants. GPLRP2 was found to hydrolyze DPPC present in mixed DPPC-NaTDC micelles but was inactive on DPPC vesicles and DPPC-Triton X100 micelles. FTIR analysis of GPLRP2 S152G interaction with the DPPC-NaTDC system showed a decrease in the conformational disorder and mobility of the acyl chains, a dehydratation of the interface, and changes in the orientation and H-bonding of DPPC polar head-groups. These effects were not observed with MLV, LUV and DPPC-Triton X100 micelles, thus indicating a specific recognition of DPPC in mixed phospholipid-bile salt micelles, in agreement with phospholipase activity measurements. Changes in the IR spectra during DPPC hydrolysis by GPLRP2 were monitored. Specific spectral features were associated to the production of lipolysis products and could be used for quantifying phospholipid lipolysis by FTIR
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Dennison, Andrew. "Neutron reflectivity studies of insulin and phosphatidylcholine floating lipid bilayers." Thesis, University of Sheffield, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.574586.
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Mateos, Diaz Eduardo. "Etude par spectroscopie infrarouge (FTIR) des interactions de la lipase pancréatique apparentée de type 2 (PLRP2) avec les phospholipides et les sels biliaires." Electronic Thesis or Diss., Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4763.
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La lipase pancréatique apparentée de type 2 du cobaye (GPLRP2) hydrolyse une grande variété de substrats lipidiques. Elle montre cependant une sélectivité selon l’organisation supramoléculaire du substrat et la présence de surfactants comme les sels biliaires (NaTDC). Nous avons utilisé la spectroscopie infrarouge (FTIR) pour étudier les interactions entres les phospholipides (DPPC), les surfactants et la GPLRP2 dans des conditions expérimentales proches de celles du tractus digestif. Pour étudier l’étape d’adsorption indépendamment de l’hydrolyse, un variant inactif de GPLRP2 (S152G) a été produit. Diverses dispersions aqueuses de phospholipides ont été préparées : des vésicules multilamellaires (MLV), unilamellaires (LUV) et des micelles mixtes DPPC-surfactant. GPLRP2 hydrolyse le DPPC présent dans des micelles mixtes DPPC-NaTDC mais n’a aucune activité sur le DPPC en phase lamellaire ou présent dans des micelles DPPC-Triton X100. L’analyse par FTIR de l’interaction de GPLRP2 S152G avec le système DPPC-NaTDC montre des changements importants dans le désordre conformationnel et la mobilité des chaînes acyles, la déshydratation de l’interface, l’orientation des têtes polaires et leurs liaisons hydrogène. Aucun effet n’est observé avec les MLV, les LUV ou le système DPPC-Triton X100. Il y a ainsi une reconnaissance spécifique du DPPC dans les micelles mixtes avec les sels biliaires, en accord avec l’activité enzymatique de GPLRP2. Les changements du spectre IR pendant l’hydrolyse du DPPC par la GPLRP2 ont été suivis. Certaines caractéristiques attribuées à la formation de produits de lipolyse peuvent être utilisées pour une étude quantitative de la lipolyse par FTIRGuinea pig pancreatic lipase-related protein type 2 (GPLRP2) hydrolyzes a large set of lipid substrates, but displays however some selectivity depending on the supramolecular structure of substrate and the presence of surfactants like bile salts (NaTDC). We used Fourier transform infrared (FTIR) spectroscopy to study the interactions between phospholipids (DPPC), surfactants and GPLRP2 under conditions close to those of the GI tract. To study the adsorption step independently from hydrolysis, a GPLRP2 inactive variant (S152G) was produced. Various phospholipid dispersions were prepared: multilamellar (MLV) and large unilamellar vesicles (LUV) and mixed micelles with surfactants. GPLRP2 was found to hydrolyze DPPC present in mixed DPPC-NaTDC micelles but was inactive on DPPC vesicles and DPPC-Triton X100 micelles. FTIR analysis of GPLRP2 S152G interaction with the DPPC-NaTDC system showed a decrease in the conformational disorder and mobility of the acyl chains, a dehydratation of the interface, and changes in the orientation and H-bonding of DPPC polar head-groups. These effects were not observed with MLV, LUV and DPPC-Triton X100 micelles, thus indicating a specific recognition of DPPC in mixed phospholipid-bile salt micelles, in agreement with phospholipase activity measurements. Changes in the IR spectra during DPPC hydrolysis by GPLRP2 were monitored. Specific spectral features were associated to the production of lipolysis products and could be used for quantifying phospholipid lipolysis by FTIR
6
Wright, Lesley Catherine. "Lipids and cancer." Thesis, The University of Sydney, 1987. https://hdl.handle.net/2123/26014.
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Transformed, embryonic and malignant cells give a high resolution 1H NMR spectrum which arises from lipids in the plasma membrane. Highly purified plasma membranes were prepared from human acute leukaemic T lymphoblasts (CCRF-CEM) in which the activity of the plasma membrane marker enzyme, 5'-nucleotidase, was enriched 45-fold. Triglyceride and cholesteryl ester each constituted about 4% of the total plasma membrane lipid, and were present in all subcellular membrane fractions isolated. Two-dimensional scalar correlated (COSY) NMR spectroscopy identified triglyceride as the main plasma membrane component giving rise to the NMR spectrum, while soluble non-membrane components accounted for 90% of the remaining resonances in the spectrum of intact cells.
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Zhang, Tejia. "Discovery of bioactive lipids and lipid pathways in cell death and disease." Thesis, Harvard University, 2014. http://dissertations.umi.com/gsas.harvard:11483.
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Apoptosis is an intricately regulated cellular process required for the health and homeostasis of living systems. The mitochondrial apoptotic pathway depends on the BCL-2 family of pro- and anti-apoptotic members whose interactions regulate cell fate. BAX and BAK are key pro-apoptotic proteins required for mitochondrial permeabilization during apoptosis. While the mitochondrial death program relies heavily on its protein components, evidences support equally crucial roles for lipids and lipid metabolism in promoting or hindering apoptosis at the mitochondria. To gain insight into the interplay between lipids and BCL-2 proteins we used a liquid chromatography (LC)-mass spectrometry (MS)-based comparative lipidomics approach to uncover lipid changes in the absence of BAX and/or BAK. Our analysis revealed novel functions for BAX and BAK in inflammation and ceramide metabolism. A targeted LC-MS workflow was also developed for characterization of a novel lipid class involved in type 2 diabetes. Targeted LC-MS revealed altered oxysterol metabolism following perturbation of the Sonic hedgehog pathway. Taken together, our findings demonstrate interesting connections among lipids, cell death and disease.Chemistry and Chemical Biology
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Subramaniam, Varuni. "Preparation and Characterization of Novel Lipid and Proteolipid Membranes from Polymerizable Lipids." Diss., The University of Arizona, 2006. http://hdl.handle.net/10150/194889.
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The work described here has focused on two types of supramolecular assemblies, supported lipid bilayers (SLBs) and giant vesicles (GVs) from polymerizable lipids. SLBs are explored extensively as structural models in biophysical studies of cell membranes and biosensor coatings. With regard to implementation as biocompatible scaffoldings for receptor-based molecular devices, fluid SLBs lack chemical, thermal and mechanical stability as lipids are self-organized by weak, noncovalent forces. One possible solution is to use synthetic lipid monomers that can be polymerized to form robust bilayers. A key question is how polymerization affects transmembrane protein structure and activity. Specifically it is unclear if lipid cross-linking can be achieved without adversely affecting the activity of incorporated proteins. In this work the effect of lipid polymerization on transmembrane protein activity was studied with rhodopsin. The protein was reconstituted into SLBs composed of polymerizable lipids, bis-SorbPC, bis-SorbPC:mono-SorbPC, bis-DenPC and bis-SorbPC:mono-SorbPE. Rhodopsin photoactivity was monitored using plasmon waveguide spectroscopy. The results show that reconstitution of rhodopsin into SLBs composed of phosphatidylcholine with the polymerizable moiety in the acyl chain terminus, followed by photoinduced cross-linking of the lipids, does not significantly perturb protein function. A possible explanation is that a bilayer with relatively low Xn retains sufficient elasticity to accommodate the membrane deformation that accompanies the conformational change associated with rhodopsin photoactivation when polymerized in the acyl chain terminus. GVs have diameters ranging from several to few hundred micrometers and thus can be observed by optical microscopic methods. This allows manipulation of individual vesicles and observation of their transformations in real time. GVs have attracted attention as microcontainers for enzymes and drugs, and as biosensors. With the aim of increasing stability for these types of applications, GVs were prepared from synthetic dienoyl lipids that can be polymerized to form robust vesicles. The stability of these vesicles after polymerization was investigated by surfactant treatment, drying and rehydration, and temperature variations. The structure of poly(GVs) was largely retained under these conditions which destroy unpolymerized vesicles. Permeability studies on poly(GVs) suggests that they could be potentially used in a variety of technological applications, including sensors, macromolecular carriers, and microreactors.
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YAMANE, Tsuneo. "Enzyme Engineering for Lipids." 名古屋大学農学国際教育協力研究センター, 2004. http://hdl.handle.net/2237/8930.
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Shin, John J. H. "Lipids as pH biosensors." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/45704.
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Oldham, Alexis Jean. "Modulation of lipid domain formation in mixed model systems by proteins and peptides." View electronic thesis, 2008. http://dl.uncw.edu/etd/2008-1/r1/oldhama/alexisoldham.pdf.
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Kamo, Tomoari. "Lipid membrane structure modulated by nonlamellar-forming lipids and interaction with amphipathic peptide." 京都大学 (Kyoto University), 2007. http://hdl.handle.net/2433/137121.
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Vlčková, Bohumila. "Testování komerčních přípravků do odlučovačů tuků." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2008. http://www.nusl.cz/ntk/nusl-216440.
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Diploma thesis was aimed at testing of five commercial products for separators of lipids. Performed study should to shown that in produts are presented lipase-produducing microoganisms, event. that in products are also lipolytics enzymes as addition. The products was cultivated by solid-state and submerged fermentations and subsequently was tested their properties as is lipolytic activity, the amount of free fatty acids etc. Solid-state fermentation used Tributyrin Agar Base where Tributyrin was used as a substrate. Submerged fermentation used special prepared medium where was olive oil. Methods using in this study served for detection and qualification of lipase-produducing microoganisms in individual products. For detection of lipase-produducing bacterial spieces was used Spirit Blue Agar. In this case was used Tributyrin and Tween 80 as a substrate. Lipolytic activity was measured by spectrophotometry and degradation of lipids was measured titrimetry. Performed study demonstrated that all tested products have ability to degradation of lipids.
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Elbert, R., André Laschewsky, and H. Ringsdorf. "Hydrophilic spacer groups in polymerizable lipids: formation of biomembrane models from bulk polymerized lipids." Universität Potsdam, 1985. http://opus.kobv.de/ubp/volltexte/2009/1736/.
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A variety of polymerizable lipids containing a hydrophilic spacer group between the reactive group and the main amphiphilic structure have been synthesized. They were investigated in monolayers, liposomes, and multilayers. When the spacer concept was used, efficient decoupling of the motions of the polymeric chain and the amphiphilic side groups is achieved. Thus, the often found loss of the important fluid phases by polymerization is avoided. Polymeric monolayers of the spacer lipid, prepared either by polymerization in the monolayer or by spreading of prepolymerized lipid, exhibit nearly identical
surface pressure-area diagrams. Most distinctly, the successful decoupling of the motions of the polymer main chain and the membrane forming amphiphilic side groups is demonstrated by the self-organization of bulk polymerized spacer lipids to polymeric liposomes. In addition, spacer lipids are able to build polymeric Langmuir-Blodgett multilayers. The decoupling of the polymer main chain and the membrane-forming amphiphilic side groups enables the deposition of already polymeric monolayers onto supports to form defined multilayers. If, alternatively, monomeric monolayers are deposited and polymerized on the support, defects in the layers due to structural changes during the polymerization are avoided by the flexible spacer group.
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Sturgeon, Raymond M. "Interplay between cations, anionic lipids, and lipid-protein interactions at the nicotinic acetylcholine receptor." Thesis, University of Ottawa (Canada), 2009. http://hdl.handle.net/10393/28070.
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Mixtures of phosphatidylcholine (PC) and phosphatidic acid (PA) are particularly effective at stabilizing a functional nicotinic acetylcholine receptor (nAChR). To test whether the ability of PA to adopt both monoanionic and dianionic states plays a role in lipid-nAChR interactions, we monitored the ionization state of PA in nAChR-reconstituted membranes. In the presence of the nAChR, PA head groups in PC/PA 3:2 membranes are stabilized in the monoanionic state. Stabilization of monoanionic PA in nAChR-reconstituted membranes accounts for some of the observed increase in membrane gel-to-liquid crystal phase transition temperature (Tm) upon nAChR incorporation, possibly by nAChR-induced pH reduction at the membrane surface. Increasing concentrations of cations at the bilayer surface and diacylglycerol within the bilayer account for the remaining shift in membrane Tm observed upon nAChR incorporation. We conclude that the nAChR, which is a cation-selective ion channel, alters its environment through both cation concentration and enzymatic activity.
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Prindiville, John S. "Circulating lipoproteins and tissue lipids: Effects of gemfibrozil on lipid metabolism in rainbow trout." Thesis, University of Ottawa (Canada), 2010. http://hdl.handle.net/10393/28555.
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Lipids support crucial functions in teleost fish, including the production of energy; lipoproteins support the movement of lipids through the vascular system. The objective of this thesis was to determine if gemfibrozil (GEM), a mammalian PPARalpha agonist pharmaceutical, could alter the circulating lipoproteins and tissue lipid metabolism in the rainbow trout, Oncorhynchus mykiss.
Injections of GEM lowered the concentration of lipoproteins and changed their size distribution, lipid and fatty acid content. These changes were associated with an increased lipoprotein lipase transcript level but not activity. GEM increased liver size but did not affect its lipid content nor the activities or transcript levels of its PPARs and mitochondrial/peroxisomal enzymes.
This thesis provides evidence that the pharmacological effects of GEM are conserved across vertebrates. Furthermore, the decreased plasma lipids and altered lipoprotein composition demonstrated here may be relevant sublethal indicators of exposure to PPARalpha agonists present in the aquatic environment.
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Steer, Peter. "Lipids and Endothelium-Dependent Vasodilation." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3424.
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Diekman, Mattheus Jozef Maria. "Thyroid hormones, lipids and endothelium." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2000. http://dare.uva.nl/document/84351.
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Suen, Yu. "Microbial biosynthesis of neutral lipids." Diss., Georgia Institute of Technology, 1986. http://hdl.handle.net/1853/25197.
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Metwally, M. M. K. "Radiation induced peroxidation of lipids." Thesis, University of Salford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356180.
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Zeng, Yi-dong B. "Geochemical studies of microbial lipids." Thesis, University of Bristol, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.235488.
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Kamath, Savita. "Characterization of residual whey lipids /." The Ohio State University, 1996. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487935958848216.
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Chilufya, Jedaidah Y., Shivakumar P. Devaiah, Richard R. Sante, and Aruna Kilaru. "Endocannabinoid-Like Lipids in Plants." Digital Commons @ East Tennessee State University, 2015. https://dc.etsu.edu/etsu-works/4747.
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Classically, endogenous fatty acid ethanolamides and their derivatives that bind to the cannabinoid receptors and trigger a signalling pathway are referred to as endocannabinoids. Although derivatives of arachidonic acid, including arachidonylethanolamine or anandamide, are the known endogenous ligands for cannabinoid receptors, other fatty acid ethanolamides or N-acylethanolamines (NAE) that vary in carbon chain length and saturation occur ubiquitously in eukaryotic organisms and play an important role in their physiology and development. The metabolic pathway for NAEs is highly conserved among eukaryotes and well characterised in mammalian systems. Although NAE pathway is only partly elucidated in plants, significant progress has been made in the past 20 years in understanding the implications of the metabolism of saturated and unsaturated endocannabinoid-like molecules in plant development and growth. The latest advancements in the field of plant endocannabinoid research are reviewed. Key Concepts Endocannabinoids are endogenous ligands of cannabinoid receptors in mammalian systems. Endocannabinoids belong to a class of small bioactive lipid molecules that are derivatives of fatty acids including their ethanolamides, referred to as N-acylethanolamines. N-Acylethanolamines are ubiquitous and their metabolic pathway is highly conserved among eukaryotes. In higher plants, only 12–18C N-acylethanolamines have been identified and their metabolic pathway is partly elucidated. The endocannabinoid-like lipids play an important role in seed germination, seedling development, flowering and cellular organisation. In plants, N-acylethanolamines also participate in mediating responses to biotic and abiotic stress.
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SPEZZANO, ROBERTO. "Lipids and Mass Spectrometry Application." Doctoral thesis, Università degli Studi di Milano, 2019. http://hdl.handle.net/2434/647470.
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During my PhD courses I focused attention on the applications of mass spectrometry in lipidomic studies. I applied mass spectrometry in several experimental models to try to observe differences in selected metabolites affected by a particular pathology.
The first project performed in experimental model of impaird lipogenesis highlighted a cross talk between altered fatty acid synthesis and neuroactive steroid levels.
The second project, mass spectrometry application allows to understand he effect of short-term diabetes on cholesterol metabolism.
In the last project lipidomic pattern was investigated in experimental model of SCA38. Results obtained highlighted as elovl5 mutation affect phospholipids profile.
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Santos, Lilia Zago Ferreira dos. "Suplementação com acido linoleico conjugado : influencia sobre a oxidação dos lipides biologicos e conteudo de lipides hepaticos de ratos Wistar saudaveis em crescimento." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/256175.
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Orientador: Admar Costa de OliveiraTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
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Resumo: Ácido linoléico conjugado (CLA) é um conjunto de isômeros geométricos e posicionais do ácido linoléico, encontrado no leite, carnes e seus respectivos derivados. Desde a sua identificação como um agente anticarcinogênico, muitos outros efeitos lhe foram atribuídos; dentre eles, o efeito antioxidante, efeito um tanto quanto intrigante ao considerar que o CLA é um dieno conjugado, ou seja, um ácido graxo em sua fase inicial de autoxidação, mas com uma de suas ligas duplas conjugadas na forma trans. O objetivo desta Tese foi avaliar o efeito da suplementação com CLA, com e sem a presença de antioxidante, sobre o processo de autoxidação dos lípides biológicos, o conteúdo de lípides totais e a morfologia hepática de ratos Wistar saudáveis em crescimento. Foi realizado um ensaio biológico onde sessenta ratos foram divididos em seis grupos (n=10): grupos C (controle), CE (controle + vitamina E), AE (AdvantEdge® CLA), AEE (AdvantEdge® CLA + Vitamina E), CO (CLA One®) e COE (CLA One® + vitamina E). Os grupos controle C e CE receberam ácido linoléico e os grupos suplementados AE, AEE, CO e COE receberam misturas comerciais de CLA distintas cujo conteúdo médio de CLA era de 76,17 % com proporções semelhantes entre os isômeros trans-10, cis-12 e cis-9, trans-11. As condições de suplementação foram padronizadas em ensaio preliminar cujos resultados permitiram concluir que a melhor concentração de CLA a ser administrada, levando em consideração os aspectos operacionais e a resposta biológica, era de 2 % em relação ao consumo de dieta. Sendo assim, os ratos foram suplementados com 2 % de CLA por meio de entubação orogástrica durante 42 dias. Para os animais que receberam vitamina E em associação com o CLA, utilizou-se acetato de a-tocoferol na concentração de 30 mg / dia. Foram determinados índice de peróxido (IP), malondialdeído (MDA), 8-iso-PGF2a isoprostana e atividade da catalase como indicadores da autoxidação lipídica. O conteúdo total de lípides do fígado foi determinado e a morfologia do órgão foi analisada por meio de microscopia eletrônica de transmissão (MET). Os resultados demonstraram que a influência do CLA sobre o processo de oxidação dos lípides biológicos depende do tipo do suplemento e do indicador utilizado e seu respectivo local de determinação (tecido ou fluído corporal). Os valores de MDA sérico (AE: 1,80±0,67 mg MDA / kg; CO: 2,43±0,61 mg MDA / kg) e a atividade sérica da catalase (AE: 4734,23±1078,93 kU / L; CO: 5916,06±2490,71 kU / L) foram significativamente menores (P £ 0,05) em comparação com o controle (MDA: 3,85±0,24 mg MDA / kg; catalase: 10496,52±5121,84 kU / L), já os valores de 8-iso-PGF2a isoprostana foram maiores (P £ 0,05) para o grupo AE (urina: 95,13±20,26 pg / mL; plasma: 18,86±3,41 pg / mL) em relação ao controle (urina: 69,46±16,65 pg / mL; plasma: 13,84±3,55 pg / mL). Quanto ao IP, este foi maior (P £ 0,05) no grupo CO (84,38±10,97mEq / kg) em comparação com o grupo controle (54,75±9,70 mEq / kg). Em ralação à associação do acetato de a-tocoferol à suplementação com CLA, esta influenciou a ação do CLA sobre a oxidação dos lípides biológicos para os indicadores catalase, MDA hepático e 8-iso-PGF2a isoprostana urinária, de forma a diminuí-la. O conteúdo dos lípides hepáticos totais não aumentou nos ratos que receberam CLA (C: 23,93±3,64 %; AE: 21,19±2,05 %; CO: 21,16±0,90 %), embora as imagens obtidas por MET tenham demonstrado que houve aumento dos glóbulos de gordura em número e tamanho, aumento esse que não alterou a morfologia do órgão, visto que tanto o citoplasma quanto as organelas celulares estavam íntegras. Esses achados permitiram concluir que a suplementação com 2 % das misturas comerciais de CLA durante 42 dias influenciou o processo de oxidação dos lípides biológicos, no entanto, não foi possível estabelecer um consenso sobre seu efeito antioxidante/pró-oxidante visto a divergência dos resultados. Quanto às imagens hepáticas obtidas por MET, essas caracterizaram uma informação de natureza qualitativa, mas não menos importante, pois permitiu concluir que esse protocolo de suplementação com CLA não promeveu danos morfológicos ao órgão visto a integridade dos hepatócitos
Abstract: Conjugated linoleic acid (CLA) is a set of geometrical and positional isomers of the linoleic acid, found in milk, meats and their products. Since its identification as an anticarcinogenic agent, other effects have been attributed to it since, among them an antioxidant action -- a rather intriguing claim in view of the fact that CLA is a conjugated diene, i.e., a fatty acid in an early stage of autoxidation, but with one of its conjugated double bonds in the trans form. The objective of this Thesis was to assess the effect of CLA supplementation, both in the presence and in the absence of an antioxidant, on: (a) the process of biological lipid autoxidation, (b) the total lipid content, and (c) the hepatic morphology of healthy growing Wistar rats. A biological assay on sixty rats divided into six groups (n=10) was realized: C (control), CE (control + vitamin E), AE (AdvantEdge® CLA), AEE (AdvantEdge® CLA + Vitamin E), CO (CLA One®), and COE (CLA One®+ vitamin E). Control groups C and CE received linoleic acid, and supplemented groups AE, AEE, CO and COE received commercial CLA mixtures with a mean CLA content 76.17% and similar proportions of trans-10, cis-12 and cis-9, trans-11 isomers. A preliminary assay was conducted in order to standardize supplementation conditions; its results indicated that the best CLA concentration for administration, taking into account operational aspects and biological response, was 2% of diet intake. Rats were supplemented with that concentration of CLA by orogastric intubation for 42 days. For animals receiving vitamin E in combination with CLA, alpha-tocopherol acetate in the concentration of 30 mg/day was used. Peroxide index (IP), malondialdehyde (MDA), 8-iso-PGF2 alpha isoprostane, and catalase activity were determined as lipid autoxidation indicators. Total liver lipid content was determined, and organ morphology was examined by transmission electronic microscopy (TEM). Results demonstrated that the influence of CLA on the process of biological lipid oxidation depends on supplement type, on the chosen indicator, and on whether it is determined in a tissue or in a body fluid. Serum values of MDA (AE: 1.80±0.67 mg MDA / kg; CO: 2.43±0.61 mg MDA / kg) and catalase serum activity (AE: 4734.23±107893 kU / L; CO: 5916.06±2490.71 kU / L) were significantly lower (P <0,05) than in the controls (MDA: 3.85±0.24 mg MDA / kg; catalase: 10496.52±5121.84 kU / L), whereas 8-iso-PGF2 alpha isoprostane were higher (P <0.05) for AE (urina: 95.13±20.26 pg / mL; plasma: 18.86±3.41 pg / mL) than in the controls (urina: 69.46±16.65 pg / mL; plasma: 13.84±3.55 pg / mL). IP values were higher (P<0,05) for CO (84,.38±1097mEq / kg) than in the control (54.75±9.70 mEq / kg). Regarding the combination of alpha-tocopherol acetate and CLA supplementation, the presence of this antioxidant influenced the action of CLA on biological lipid oxidation as indicated by catalase, hepatic MDA and urinary 8-iso-PGF2 alpha isoprostane. Total hepatic lipid content did not increase in rats receiving CLA (C: 23.93±3,.64 %; AE: 21.19±2.05 %; CO: 21.16±0.90 %), although TEM images showed an increase in size and amount of fat globules; this, however, did not change organ morphology, as indicated by the fact that cell cytoplasm and organelles were undamaged. These findings allowed to conclude that supplementation with 2% of commercial CLA mixtures for 42 days influenced the process of biological lipid oxidation. However, no conclusion could be reached as to its anti-oxidant or prooxidant effect, because of inconsistencies in the results. Hepatic TEM images, even being a qualitative information, were nevertheless important, as they allowed to conclude that this CLA supplementation protocol did not cause any morphological damage to the organ, as indicated by the integrity of hepatocytes
Doutorado
Nutrição Experimental e Aplicada à Tecnologia de Alimentos
Doutor em Alimentos e Nutrição
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Lehmal, Heidi. "Adaptation an niedrige Temperaturen: Lipide in Eisdiatomeen = Adaptation to low temperatures: lipids in ice diatoms /." Bremerhaven : Alfred-Wegener-Institut für Polar- und Meeresforschung, 1999. http://www.gbv.de/dms/bs/toc/302157891.pdf.
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Förster, Julia. "Genomweite Untersuchung einer sorbischen Kohorte zur Identifikation neuer mit dem Lipidstoffwechsel assoziierter Polymorphismen." Doctoral thesis, Universitätsbibliothek Leipzig, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-102123.
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Lipide erfüllen als Energiespeicher und Element verschiedener Verbindungen für den Organismus lebenswichtige Funktionen. Verändert sich ihre Konzentration im Blut spricht man von Dyslipidämien. Diese stellen, insbesondere als Risikofaktor für kardiovaskuläre Erkrankungen, vor allem in Industrienationen ein bedeutendes gesundheitsökonomisches Problem dar.
Verschiedene Studien identifizierten in den letzten Jahren zahlreiche Genloci, die den Lipidstoffwechsel beeinflussen. Darunter befinden sich Gene wie APOC1, CETP oder LPL, die aufgrund ihrer Funktionalität eindeutig dem Fettstoffwechsel zuzuordnen sind. Zusätzlich gerieten bisher unbekannte Loci in den Gegenstand der Forschung. Zusammen erklären diese Loci derzeit lediglich 25 - 30 % der phänotypischen Ausprägung.
In der vorliegenden Studie wurde mittels genomweiter Assoziationsstudien (GWAS) nach weiteren, potentiell im Zusammenhang mit den Merkmalen HDL-, LDL-Cholesterol und Triglyceriden stehenden Genloci gesucht. Dazu wurde in einer eigenständigen Population, den Sorben aus der Oberlausitz, eine genomweite Assoziationsstudie (N = 839) durchgeführt. Es zeigten sich 13 signifikant assoziierte Loci mit einem P-Wert < 10 5. Anschließend wurden SNPs mit einem P-Wert < 0,01 in der sorbischen Kohorte für eine Metaanalyse mit den Daten der Probanden der Diabetes Genetics Initiative (N ~ 2600) ausgewählt. So konnten 21 Genloci mit einem kombinierten P-Wert < 10 4 bestätigt werden. Von diesen wurden 5 neu identifizierte, bisher nicht publizierte Varianten in der unabhängigen Metabolisches Syndrom Berlin Potsdam Kohorte (N = 2000) repliziert. Mit einem P-Wert von 1,78x10 7 zeigte die Variante rs8135828 im THOC5 Gen für den Parameter HDL-Cholesterol die stärkste Assoziation in der kombinierten Metaanalyse aller 3 Kohorten.
Weitere Analysen sind notwendig, um die Funktionen und den Regulationsmechanismus der identifizierten SNPs auf den Fettstoffwechsel genau zu verstehen.
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Musigamart, Natedao. "Study of the role of lipids from maturated coagula from Hevea brasiliensis latex on natural rubber behavior in oxidative conditions." Thesis, Montpellier, SupAgro, 2015. http://www.theses.fr/2015NSAM0004/document.
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Le caoutchouc naturel (CN), un produit dérivé du latex d'Hevea brasiliensis, est connu pour ses propriétés mécaniques supérieures pour certaines à celles de ses concurrents synthétiques. Néanmoins, le haut degré d'insaturation du poly(cis-1,4-isoprene) le rend susceptible à la thermo-oxydation. Heureusement, le CN est doté de composés non-isoprènes dont certains ont des propriétés antioxydantes. Les lipides sont les plus importants non-isoprènes retenus dans le caoutchouc et contiennent des molécules à activité antioxydante en particulier les tocotriènols. Il est connu que durant la maturation de coagula de latex, la composition chimique et les propriétés du caoutchouc obtenu sont altérées, mais les mécanismes complexes de cette altération ne sont pas encore complètement élucidés. Dans cette étude, l'évolution de certaines molécules antioxydantes natives pendant la maturation a été suivie en relation avec certaines propriétés physiques du caoutchouc. Deux expérimentations de maturation ont été mises en œuvre. La première mettait en jeu des conditions non contrôlées de maturation suivies d'un procédé de confection du caoutchouc basé sur celui des feuilles fumées (RSS) ou non (USS). La seconde a été conduite dans un dispositif expérimental dédié permettant le contrôle des facteurs de l'environnement tels que l'humidité relative, la température et la concentration en oxygène. Le procédé de confection du caoutchouc était dans ce cas basé sur celui des caoutchoucs spécifiés techniquement (TSR). L'évolution des échantillons pendant la maturation a été étudiée à différentes échelles : propriétés en masse (P0, P30 et PRI), mésostructure (% gel, Mw and Mn) et composition biochimique (lipides). En parallèle, l'activité antioxydante in vitro des extraits lipidiques correspondants a été mesurée en utilisant une méthode DPPH optimisée. La quantité et la qualité des lipides extraits évoluent pendant la maturation, en particulier en aérobiose. La quantité totale de lipides décroit, avec, en début de maturation, une libération d'acides gras dont la quantité diminue ensuite, avec une disparation des espèces insaturées en premier. La quantité de γ-tocotrienol libres extraits change peu au cours de la maturation alors que sa forme estérifiée montre un enrichissement en acides gras saturés. L'activité antioxydante de l'extrait lipidique mesurée in vitro est corrélée avec la concentration de γ-tocotrienol libre mais pas avec les valeurs de P30 et PRI qui estiment la résistance du caoutchouc à la thermo-oxydation. Cette absence de corrélation pourrait être due à la différence des conditions de mesure in-vitro de celles existantes au sein du matériau caoutchouc. La localisation des antioxydants dans le caoutchouc et en particulier leur possibilité physique d'interagir avec les doubles liaisons du poly(cis-1,4-isoprene) ou avec des espèces oxydantes reste à étudier afin de comprendre ce qui régit la chute de P30 au cours de la maturation. Des lipides non extractibles ou des molécules non-isoprènes plus polaires (protéines, polyphénols, …) pourraient également influencer la résistance du caoutchouc à la thermo-oxydationNatural rubber (NR), a derived product from H. brasiliensis latex, is known for its high mechanical properties that are, for some, superior to those of its synthetic counterparts. However, the high degree of unsaturation of poly(cis-1,4-isoprene) makes it susceptible to thermo-oxidation. Fortunately, NR is endowed with non-isoprene components of which some have antioxidant properties. Especially, lipids, the main non-isoprene component retained in NR, have been reported to contain antioxidant substances, especially tocotrienols. It is well known that during the maturation of latex coagula, both NR physical properties and chemical composition are altered, but the complex mechanisms of this alteration are still to be elucidated. In the present work, the evolution of some native antioxidant molecules during maturation was followed in relation with some physical properties. Two experimental conditions of maturation were chosen. The first experiment involved uncontrolled conditions based on traditional unsmoked (USS) or ribbed smoked sheet (RSS) processing, while the second was performed in a dedicated maturation device with full control of environmental factors (relative humidity, temperature and oxygen content) followed by a processing based on that of Technically Specified Rubber (TSR). The evolution of samples during maturation was studied at different scales: bulk properties (P0, P30 and PRI), mesostructure (% gel content, Mw and Mn) and biochemical composition (lipids components). In parallel, in vitro antioxidant activity of NR lipid extracts was also investigated using an optimized DPPH method. Lipid quantity and quality evolved during maturation, especially under aerobic conditions. The total amount of lipid extract decreased, with a release of free fatty acids at early stage of maturation followed by a later decrease, unsaturated fatty acids being the first to disappear. The amount of extractable free γ-tocotrienol did not change much during maturation, while its esterified form was enriched in saturated fatty acids. The antioxidant activity measured in vitro correlated well with free γ-tocotrienol concentration but not with the resistance of rubber to thermo-oxidation assessed by P30 or PRI. Indeed, the in vitro conditions of measurement were far from those occurring inside rubber material. The localization of antioxidants in rubber and especially their physical possibility to interact with the double bonds of poly(cis-1,4-isoprene) or with oxidant species should be further investigated to understand what drives the drop of P30 along maturation time. Non extractable lipids or more polar non-isoprene molecular species (proteins, polyphenols, etc…) could also influence the resistance to thermo-oxidation
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Berg, Anna-Lena. "Hepatic lipase methodological and clinical studies with special reference to its regulation by ACTH /." Lund : Depts. of Clinical Chemistry and nephrology, University of Lund, 1994. http://catalog.hathitrust.org/api/volumes/oclc/39099405.html.
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Wu, Yu. "Neuroprotective liquid crystalline cubosome and hexosome nanoparticle formulations by self-assembly of plasmalogen lipids and a neurotrophic peptide." Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASQ003.
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L'objectif principal de cette thèse est d'étudier l'effet neuroprotecteur des plasmalogènes (Pls) et d'explorer le potentiel des nanoparticules lipidiques contre les maladies neurodégénératives. Notre stratégie vise à créer un système auto-assemblé, augmentant l'efficacité des plasmalogènes et d'un neuropeptide, le polypeptide activateur de l'adénylate cyclase hypophysaire (PACAP), pour la neuroprotection. Pls, un groupe distinctif de glycérophospholipides membranaires, contiennent généralement une chaîne d'acyle gras polyinsaturé en position sn-2 et une chaîne alkyle liée par une liaison éther-vinyle en position sn-1 du squelette glycérol. La correction du déclin des niveaux de plasmalogènes chez les personnes âgées offre des perspectives pour les thérapies liées à la maladie de Parkinson, à la maladie d'Alzheimer et à la démence. Nous résumons les progrès des nanoparticules lipidiques (LNPs) dans le ciblage de multiples mécanismes de neurodégénérescence. Notre recherche sur les LNPs chargées en plasmalogène explore leur impact in vitro/in vivo sur des modèles de neurodégénérescence. Notre étude montre la faisabilité d'améliorer l'efficacité du Pls avec les LNPs. Nous utilisons des plasmalogènes naturels pour créer des nanoformulations impliquant un excipient lipidique nonlamellaire (monooléine, divers agents tensioactifs et de petites quantités de vitamine E, curcumine ou coenzyme Q10. En utilisant la méthode SAXS, nous avons identifié des caractéristiques structurelles des LNPs (vésicules, cubosomes et hexosomes). Les évaluations in vitro utilisent des cellules SH-SY5Y, différenciées avec 10 µM d'acide rétinoïque pendant 5 jours. Les tests de viabilité cellulaire indiquent une absente de toxicité à une concentration totale en lipides de 10 µM pour une incubation de 24 heures. Nous avons étudié l'impact des nanoparticules chargées en Pls sur les cellules neuronales en utilisant la neurotoxine 6-OHDA comme modèle in vitro de la maladie de Parkinson. Nous explorons les mécanismes de dommages cellulaires (stress oxydatif et enzymes apoptotiques), identifiant la voie de signalisation ERK-Akt-CREB-BDNF. Cela suggère la nécessité d'adopter plusieurs stratégies dans le traitement des maladies neurodégénératives. Plusieurs composés neuroprotecteurs documentés ont été utilisés pour démontrer la capacité à restaurer les lésions neuronales causées par le 6-OHDA, offrant un modèle de conditions neurodégénératives pour élucider davantage les effets bénéfiques des Pls. Nous nous concentrons ensuite sur la protéine de liaison à l'élément de réponse au cAMP (CREB) et sa phosphorylation conduisant à l'expression des neurotrophines, cruciale pour prévenir les troubles neurologiques. À travers des nano-assemblages lipidiques-peptiques, nous avons étudié l'impact des différentes organisations structurelles des LNPs sur la phosphorylation de CREB dans un modèle in vitro de la maladie de Parkinson. Dans un modèle murin de la maladie de Parkinson, les LNPs de structure vésiculaire et hexosomale ont démontré une efficacité distincte dans la restauration de la fonction motrice. L'intervention intranasale a influencé la régulation génétique liée à la maladie de Parkinson et rééquilibré les profils lipidiques. L'administration nasale de LNPs chargées en Pls a amélioré les symptômes comportementaux de la maladie et a régulé à la baisse des gènes tels que IL33 et Tnfa. Nos résultats indiquent l'impact significatif des nanoformulations hexosomales sur l'atténuation de la maladie, le métabolisme lipidique et les modifications génétiques réactives potentiellement impliquées dans la régénérationThe primary aim of this thesis is to investigate the neuroprotective effect of plasmalogens (Pls) and explore the potential of lipid nanoparticles against neurodegenerative diseases. Our strategy aims to create a self-assembled system, enhancing the efficacy of plasmalogens and the neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) for neuroprotection. The Pls, a distinctive group of membrane glycerophospholipids, typically contain a polyunsaturated fatty acyl chain at the sn-2 position and an alkyl chain linked by a vinyl-ether bond at the sn-1 position of the glycerol backbone. Pls, with their unique structure featuring a vinyl ether bond, possess free radical scavenging capabilities and antioxidant properties. Addressing the decline in plasmalogen levels in aging individuals holds promise for therapies related to Parkinson's disease, Alzheimer's disease, and dementia. Recent research has expanded our understanding of their antioxidant effects, anti-inflammation, and their involvement in ferroptosis. However, challenges persist in implementing plasmalogens in treatments of neurodegenerative diseases and in developing suitable drug delivery systems. We summarize the progress in lipid nanoparticles (LNPs) for targeting multiple neurodegeneration mechanisms. Our research on plasmalogen-loaded LNPs explores their fabrication mechanism and in vitro/in vivo impacts on neurodegenerative models. Our study shows the feasibility of enhancing Pls efficacy using LNPs as carriers. We employ natural plasmalogens from scallops to create nanoformulations involving a non-lamellar lipid excipient (MO) for structural stabilization, various surfactants, and small amounts of vitamin E, curcumin, or coenzyme Q10. Using small-angle X-ray scattering (SAXS), we identified the structural features of various LNPs (vesicles, cubosomes, and hexosomes). Our in vitro evaluations utilized human neuroblastoma SH-SY5Y cells, differentiated with 10 µM retinoic acid for 5 days. Cell viability tests indicated non-toxicity of the LNPs at a total lipid concentration of 10 µM for 24-hour incubation. We study the impact of Pls nanoparticles on an in vitro model of Parkinson's disease using neuronal cells induced by the neurotoxin 6-OHDA. Using the SH-SY5Y cell line, we explore cellular damage mechanisms (oxidative stress and apoptotic enzymes) via identifying the impact on the ERK-Akt-CREB-BDNF signaling pathway. Several documented neuroprotective compounds were used to demonstrate the ability to restore neuronal lesions caused by 6-OHDA, offering a model of neurodegenerative conditions to further elucidate the beneficial effects of the Pls-based LNPs. We then focus on the cAMP response element binding protein (CREB) and its phosphorylation leading to neurotrophin expression, crucial in preventing neurological disorders. Through lipid peptide nano-assemblies, we studied the impact of different structural organizations of the LNPs on CREB phosphorylation in an in vitro model of Parkinson's disease. Notably, liquid crystalline lipid nanoparticles loaded with plasmalogens prolonged CREB activation under neurodegenerative conditions, showing potential for enhanced neuroregeneration through sustained CREB activation in response to the neurotrophic nanoassemblies. In a mouse model of Parkinson's disease, vesicle and hexosome LNPs demonstrated distinct effectiveness in restoring motor function. The nanomedicine-mediated intervention influenced Parkinson's disease-related gene regulation and rebalanced lipid profiles. Nasal administration of Pls-loaded LNPs improved disease behavioral symptoms and downregulated genes like IL33 and Tnfa. The obtained results indicated the significant impact of hexosomal LNP nanomedicines on disease attenuation, lipid metabolism, and responsive gene modifications potentially involved in regeneration
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Zhou, Albert Lihong. "Bioactivities of Milk Polar Lipids in Influencing Intestinal Barrier Integrity, Systemic Inflammation, and Lipid Metabolism." DigitalCommons@USU, 2013. http://digitalcommons.usu.edu/etd/1517.
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The purpose of lactation is for nutrient provision and also importantly for protection from various environmental stressors. Milk polar lipids reduce cholesterol, protect against bacterial infection, reduce inflammation and help maintain gut integrity. Dynamic interactions within dietary fat, lipid metabolism, gut permeability and inflammatory cytokines remain unclear in the context of obesity and systemic inflammation. A rat model and three mouse models were developed to test the hypotheses that dietary milk polar lipids may affect lipid metabolism and intestinal integrity and may protect against systemic inflammation in the context of stressful diet, systemic inflammation, and obesity. The milk polar lipids isolates had complex effects on lipid metabolism and associated gene expression in the rat model. There were complex dynamics in lipid metabolism, gut permeability and systemic inflammation at different time points in all mouse models. The milk phospholipids increased gut permeability in genetic and diet-induced obesity and during the lipopolysaccharide (LPS) -induced inflammation. The phospholipids increased the plasma LPS level in genetic obesity and during the LPS stress. The phospholipids reduced liver mass and liver lipids in genetic obesity and during the LPS-induced inflammation. The phospholipids increased the body fat in the diet-induced obesity model. The milk gangliosides did not significantly affect gut permeability, systemic inflammation, and lipid metabolism in all three mouse models. Current estimate by the Centers for Disease Control is that about 1/3 Americans are obese (body mass index, BMI ≥ 30) and 1/3 Americans are overweight (25 ≤ BMI < 30). More than 25% of Americans today have a fatty liver which could lead to further health problems. The data from this dissertation shed light on the complicated interrelationships between gut permeability, systemic inflammation, and lipid metabolism in obesity. The results contribute to our understanding of the bioactivities of milk polar lipids and provide scientific evidence for the role of milk polar lipids rich materials in affecting biological functions. The study of the influence of milk polar lipids on gut barrier integrity adds new information on understanding the mechanisms of gut leakiness and recovery. The investigation of the impact of milk polar lipids on lipid metabolism reveals new perspectives for the development of diet-induced obesity.
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Jeffery, Nicola. "Studies of the effects of dietary lipid manipulation upon blood lipids and immune cell function." Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320212.
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Horn, Patrick J. "Development of Enabling Technologies to Visualize the Plant Lipidome." Thesis, University of North Texas, 2013. https://digital.library.unt.edu/ark:/67531/metadc499986/.
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Improvements in mass spectrometry (MS)-based strategies for characterizing the plant lipidome through quantitative and qualitative approaches such as shotgun lipidomics have substantially enhanced our understanding of the structural diversity and functional complexity of plant lipids. However, most of these approaches require chemical extractions that result in the loss of the original spatial context and cellular compartmentation for these compounds. To address this current limitation, several technologies were developed to visualize lipids in situ with detailed chemical information. A subcellular visualization approach, direct organelle MS, was developed for directly sampling and analyzing the triacylglycerol contents within purified lipid droplets (LDs) at the level of a single LD. Sampling of single LDs demonstrated seed lipid droplet-to-droplet variability in triacylglycerol (TAG) composition suggesting that there may be substantial variation in the intracellular packaging process for neutral lipids in plant tissues. A cellular and tissue visualization approach, MS imaging, was implemented and enhanced for visualizing the lipid distributions in oilseeds. In mature cotton seed embryos distributions of storage lipids (TAGs) and their phosphatidylcholine (PCs) precursors were distribution heterogeneous between the cotyledons and embryonic axis raising new questions about extent and regulation of oilseed heterogeneity. Extension of this methodology provides an avenue for understanding metabolism in cellular (perhaps even subcellular) context with substantial metabolic engineering implications. To visualize metabolite distributions, a free and customizable application, Metabolite Imager, was developed providing several tools for spatially-based chemical data analysis. These tools collectively enable new forms of visualizing the plant lipidome and should prove valuable toward addressing additional unanswered biological questions.
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Danial, John Shokri Hanna. "Imaging lipid phase separation on droplet interface bilayers." Thesis, University of Oxford, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.711943.
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Gomez, Rodrigo Enrique. "Unravelling the contribution of lipids in plant autophagy : Identification and functional characterization of lipids implicated in the autophagic process in Arabidopsis." Thesis, Bordeaux, 2021. http://www.theses.fr/2021BORD0103.
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Les plantes, étant des organismes sessiles, sont fréquemment confrontées à une grande variété de stress environnementaux. Ces conditions peuvent conduire à l'accumulation d'agrégats de protéines ou au disfonctionnement de multiples organites intracellulaires. Pour faire face à ces conditions, les plantes ont mis au point des mécanismes d'adaptation sophistiqués qui permettent le recyclage des composants intracellulaires. Ces mécanismes sont essentiels pour les remodelages métaboliques nécessaires à un recyclage efficace des nutriments ainsi qu'à l'élimination des composants nocifs pour la cellule comme des organites endommagés. L'un de ces mécanismes est l'autophagie, une voie de dégradation intracellulaire qui utilise des vésicules à double membrane qui encapsulent des portions du cytoplasme et le délivrent à la vacuole où elles sont dégradées. L'autophagie repose sur la formation de ces vésicules spécialisées, appelées autophagosomes (AP). Les AP sont des vésicules uniques dans le système endomembranaire, d'abord parce qu'elles sont constituées d'une double couche lipidique, et ensuite parce qu'elles ne bourgeonnent pas à partir d'un compartiment déjà existant. La biogenèse des AP est un processus en plusieurs étapes impliquant une machinerie centrale (protéines ATG) qui intervient dans la formation de novo d'une membrane initiale ; puis, par l'addition de lipides, cette membrane s’agrandit et devient une structure en forme de coupe avec des bords fortement incurvés lui permettant d’engloutir la cargaison autophagique. Une fois la cargaison engloutie, ses bords fusionnent afin de fermer la structure, qui circule ensuite vers la vacuole, où sa membrane externe fusionne avec la membrane de la vacuole ce qui libère la membrane interne et la cargaison à l'intérieur de la vacuole pour sa dégradation. Ainsi, la biogenèse des AP repose sur de nombreux événements de remodelage membranaire, d'abord pour initier la membrane initiale, puis pour maintenir sa forme très incurvée tout en assurant son expansion, et enfin pour sceller les structures matures et promouvoir sa fusion ultérieure à la vacuole. Dans les membranes biologiques, les lipides, grâce à leurs propriétés physico-chimiques, définissent des caractéristiques importantes telles que la fluidité, la courbure ainsi que les champs électrostatiques des membranes. Par conséquent, le rôle crucial des lipides dans l'autophagie a émergé ces dernières années. Chez les plantes, on ne connait encore que très peu de choses sur la composition lipidique des membranes autophagiques et les fonctions des lipides dans la formation des AP restent largement méconnu. Mon travail de thèse a consisté à identifier des acteurs lipidiques et protéiques impliquées dans l'autophagie chez les plantes dans le but de caractériser leur fonction dans le processus. En effectuant un criblage d'inhibiteurs enzymatiques nous avons analysé l'impact de l'inhibition de la synthèse de différentes espèces de lipides sur l'autophagie. En utilisant cette approche, nous avons identifié différents candidats lipidiques importants pour l'autophagie des plantes. Notamment, nous avons identifié le phosphatydilinositol-4-phosphate (PI4P) comme étant critique pour la formation des APs. En l'absence dePI4P, la formation des AP est stoppée à un stade très précoce, ce qui entraîne un blocage total dans le processus. De plus, nous avons obtenu des informations précieuses pour mieux comprendre la formation des APs chez les plantes. En particulier, nos résultats suggèrent que la membrane plasmique (PM) semble jouer un rôle important dans la formation de ces structures. Dans leur ensemble, nos résultats ont confirmé notre hypothèse initiale: les lipides ne sont pas seulement des éléments inertes qui constituent les membranes autophagiques ;ils semblent plutôt jouer des rôles distincts et avoir des fonctions spécifiques dans le processusPlants, being sessile organisms, are frequently confronted to a plethora of environmental stresses and harsh conditions. Enduring these conditions can lead to the accumulation of protein aggregates or organelles that become dysfunctional. To withstand these conditions, plants have evolved sophisticated adaptation mechanisms for the recycling of intracellular components. These mechanisms are essential for the metabolic transitions required for efficient nutrient use, as well as proper disposal of protein aggregates or damaged organelles. One of these mechanisms is autophagy, an intracellular degradation pathway that employs specialized double membrane vesicles that encapsulate cytosolic material and delivers it to the vacuole for degradation. Autophagy relies on the formation of these specialized vesicles, called autophagosomes (APs). APs are unique vesicles in the endomembrane system, first because they are made of a double lipid bilayer, and second because they do not but from a pre-existing compartment. AP biogenesis is a multistep process implicating a core machinery (ATG proteins) that mediate the de novo formation of an initial membrane; then, by the addition of lipids, this membrane expands into a cup-shaped structure with highly curved edges to engulf autophagic cargo. Upon completion, the rims of the structure seal and form a mature AP that traffics to the vacuole, where its outer membrane fuses with the tonoplast releasingthe inner membrane and cargo inside the vacuole. Thus, AP biogenesis relies on numerous membrane remodeling events, first to initiate the initial membrane, then to maintain the highly curved shape of the structure while ensuring its expansion, and finally to seal the mature structures and its subsequent fusion to the vacuole. Lipids, thanks to their physicochemical properties define important membrane features such as its, fluidity, curvature and electrostatics. Hence, evidence showing the crucial role of lipids in autophagy has emerged in the recent years. In plants however, little is known about the lipid composition of autophagic membranes and thus, about the functional contribution of lipids in plant autophagy. My PhD thesis consisted on identifying crucial lipids for plant autophagy with an aim to characterize their function in the process. By performing a lipid-related enzymes inhibitor screen in which we assayed the impact of inhibiting the synthesis of specific lipids on autophagy, we identified different lipid candidates important for plant autophagy. Notably, we identified the phosphatydil-inositol-4-phosphate (PI4P) as being critical for the formation of APs. In the absence of PI4P, AP formation is stalled at a very early stage resulting in a block in the process. Furthermore, we have obtained valuable insights to better understand the AP formation. In plants, particularly, our results suggest that the plasma membrane (PM) plays important roles in the formation of these structures. Taken together, our results confirmed that lipids are more than just building blocks constituting the autophagic membranes; rather, they seem to play distinct and specific roles in the pathway. Finally, this thesis highlights how lipids are key actors for the autophagic process and thus for plants adaptations to adverse and stressful environmental conditions
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Kaur, Gurpreet. "Microbial membrane lipids in geothermal environments." Thesis, University of Bristol, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.503942.
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Geothermal environments, in particular their chemistry and microbiology, are of broad scientific interest with respect to the formation of mineral deposits (e.g. Jones et al. 1997) and the ecology of extremophiles, a key component of origin of life studies and astrobiology (e.g. Stetter, 1996). Lipid biomarkers, in comparison to DNA and RNA, are relatively well preserved in geothermal sinters and it is likely that such compounds. once encased in the silica matrix, could persist for extended periods of time (Pancost et al., 2005). Consequently, they can be used to gain insight into microbial diversity and, where preserved in ancient materials, assess past changes in environmental conditions.
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Sharma, Monika. "ROLE OF LIPIDS IN TOMBUSVIRUS REPLICATION." UKnowledge, 2011. http://uknowledge.uky.edu/gradschool_diss/845.
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Positive-strand RNA virus group are the most abundant among viruses affecting plants and animals. To successfully achieve replication, these viruses usurp or co-opt host proteins. To facilitate the discovery of host factors involved in Tomato bushy stunt virus (TBSV), yeast has been developed as a surrogate model host. Genome-wide approaches covering 95% of yeast genes, has revealed approximately hundred factors that could affect virus replication. Among the identified host factors, there are fourteen yeast genes, which affect/regulate lipid metabolism of the host.
One of the identified host gene is ERG25, which is an important factor for sterol biosynthesis pathway, affecting viral replication. Sterols present in eukaryotes affect the lipid composition of membranes, where tombusviruses, similar to other plus-strand viruses of tobacco, replicate. Since potent inhibitors of sterol synthesis are known, I have tested their effects on tombusvirus replication. We demonstrated that these sterolsynthesis inhibitors reduced virus replication in tobacco protoplasts. Virus replication is resumed to the wild type level by providing phytosterols in tobacco protoplasts confirming the role of sterols in RNA virus replication in tobacco.
We have also identified INO2, a transcription factor for many phospholipid biosynthetic genes, reduces virus replication in its deletion background. When we provided this gene product in the mutant background, viral replication was back to normal, confirming the role of Ino2p in tombusvirus replication. Further biochemical assays showed that the viral inhibition is because of alteration in the formation of the viral replicase complex. Using confocal microscopy, we showed that the viral replication protein, termed p33, is forming large and few punctate structures rather than the small and many by overexpressing Ino2p in the wild type yeast cells. Over-expression of Opi1, an inhibitor of Ino2p led to greatly reduced viral replication, further supporting the roles of the phospholipid pathway in tombusvirus replication.
One of the phospholipid, which is regulated by this pathway, is cardiolipin an important component of the mitochondrial as well as peroxisomal membranes. We further characterized how cardiolipin is playing an important role for tombusvirus replication by using different biochemical approaches.
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Minabe, Masaharu. "The lipids of post-fermentation yeast." Thesis, Heriot-Watt University, 1992. http://hdl.handle.net/10399/1487.
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Adhamy, Asghar. "Selective hydrolysis of lipids using lipases." Thesis, Teesside University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328090.
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Anderson, Richard Anthony. "Lipids, oxidative stress and endothelial function." Thesis, King's College London (University of London), 2004. https://kclpure.kcl.ac.uk/portal/en/theses/lipids-oxidative-stress-and-endothelial-function(ca261d48-d716-4156-9a38-dbb72775b36a).html.
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Thomas, Alyson. "Thermal adaptation of bacterial membrane lipids." Thesis, Cardiff University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277109.
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Barbary, O. M. "Effects of ionizing radiation on lipids." Thesis, University of Salford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372135.
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Wan, Jung Wing. "Novel ether lipids as antineoplastic agents." Thesis, University of Southampton, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242627.
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Tymkewycz, Paulina M. "Biologically active lipids and platelet function." Thesis, University of Edinburgh, 1987. http://hdl.handle.net/1842/30866.
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Anthony, Renil J. "Solvent Extraction of Lipids from Microalgae." Ohio University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1280854965.
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Gonçalves, José Manuel Carita. "Photosensitizer effect in Aeromonas salmonicida lipids." Master's thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/13334.
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Mestrado em MicrobiologiaPhotodynamic inactivation is a simple and effective method to destroy microorganism. PDI combines the use of light with a photosensitizer, as porphyrins, which in the presence of oxygen, leads to the formation of reactive oxygen species, such as singlet oxygen and free radicals, capable to oxidize vital membrane structures. The key advantages of Photodynamic Therapy (PDI) are the efficacy in bacteria, fungi, yeasts and protozoa; the low level of resistance induction; and the use of a cheap light source. It is fundamental to understand the importance of cell targets to better understand the photooxidation process. Lipids are important membrane components in bacteria. The main goal of this study was to evaluate the charge effect of four porphyrin derivatives used as photosensitizers in PDI in the photo-oxidation of membrane lipids of Aeromonas salmonicida and relate with the inactivation of this bacterium. The goal was achieved by quantification of lipid hydroperoxides by FOX II method, fatty acid profiles analysis by GC-FID and viability assays; in different periods of light exposure. After PDI it was observed formation of lipid hydroperoxides, changes in the fatty acids profile and a decrease on cell survival. However the results are dependent on the porphyrin used. According to these results, the photooxidation is not directly proportional with the number of charges in the photosensitizers, as other studies had been reported. A direct relation between the photo-oxidation of membrane lipids with the photo-inactivation in the studied bacterium was observed and an order of effectiveness was established. This study reinforces that cationic porphyrins are effective to inactivate bacteria and the importance and efficiency of photodynamic inactivation, as a viable alternative to traditional procedures.
A Inactivação fotodinâmica é um método simples e eficiente na inactivação de microorganismos. Inactivação fotodinâmica combina o uso de luz com um fotosensibilizador, como por exemplo porfirinas, que na presença de oxigénio gera a formação de espécies reactivas de oxigénio, como o oxigénio singleto e radicais livres, que são capazes de oxidar componentes membranares vitais. As principais vantagens da Terapia Fotodinâmica (TFD) são a sua eficiência na inactivação de bactérias, fungos, leveduras e protozoários; o baixo nível de indução de resistência; e o uso de fontes de luz baratas. Para melhor compreender esta técnica, é fundamental compreender o seu mecanismo de acções em alvos celulares. Os lípidos são importantes componentes nas membranas bacterianas, que muito recentemente foram reconhecidos como um dos alvos da PDI, e que podem estar envolvidos no processo de inactivação bacteriana. O principal objectivo deste estudo foi avaliar o efeito de quatro derivados porfirínicos utilizados com fotosensibilizadores em PDI, na foto-oxidação de lípidos membranares em Aeromonas salmonicida, e relacionar este efeito com a inactivação desta bactéria. Para tal foram realizados testes para a avaliação da peroxidação lipídica, através da quantificação de hidroperóxidos lípidos por FOX II e pela análise da variação do perfil de ácidos gordos por GC-FID em diferentes tempos de exposição à luz. Os resultados obtidos foram correlacionados ensaios de viabilidade celular; Após PDI foi observada a formação de hidroperóxidos lipídico, alterações no perfil de ácidos gordos e diminuição da sobrevivência celular. No entanto estes resultados estão dependentes na escolha da porfirina, tal como outros estudos demonstram. Foi possível estabelecer uma relação directa entre a fotooxidação dos lípidos membranares com a foto-inactivação da bactéria em estudo e estabelecer uma ordem de eficiência para as quatro porfirinas. Este estudo vem reforçar que as porfirinas catiónicas são eficientes na inactivação de bactérias e que a inactivação fotodinâmica é importante e eficiente, sendo uma técnica viável alternativa a metodologias tradicionais.
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Moran, Josephine. "Staphylococcal responses to antimicrobial skin lipids." Thesis, University of Liverpool, 2014. http://livrepository.liverpool.ac.uk/2007282/.
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Antimicrobial lipids on skin are proposed to form a barrier against microbial colonisation. Skin lipids, such as unsaturated fatty acids and sphingosines, cause membrane permeabilisation and/or proton motive force disruption . These lipids may be crucial in determining the diversity and degree of staphylococcal skin colonisation. Specifically, antimicrobial lipids may inhibit skin colonisation by Staphylococcus aureus while permitting the growth of Staphylococcus epidermidis. Here it was shown that skin fatty acids sapienic acid and linoleic acid are more active against S. aureus than S. epidermidis. This supports a role for fatty acids in the prevention of S. aureus skin colonisation. The most anti-staphylococcal skin lipid tested was D-sphingosine; no differences in resistance levels between S. aureus and S. epidermidis to D-sphingosine were observed. The genetic response and basis for resistance to skin antimicrobial lipids of S. epidermidis and S. aureus was investigated using next generation sequencing. The transcriptomic response of both species to sapienic acid was determined using RNA-Seq. Additionally, S. epidermidis and S. aureus were passaged in sapienic acid or D-sphingosine. Isolates with increased lipid resistance after passaging were genome sequenced, and mutations associated with increased resistance were characterised. From these approaches, several genes and pathways potentially involved in the responses of both species to skin lipids became apparent. These components included cell wall biosynthesis, transport and production of small molecules, ammonia production, albumin binding proteins and putative lipid efflux pumps. Cellular components identified as specifically involved in S. aureus resistance to sapienic acid included capsule and staphyloxanthin biosynthesis. Cellular components involved specifically in S. epidermidis resistance to sapienic acid were also speculatively identified, though the functions of these components were not resolved. This study has increased our understanding of staphylococcal molecular interactions with host antimicrobial lipids, which could lead to applications in the design of novel antimicrobial compounds.
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Evans, D. A. "Molecular dynamics simulations of skin lipids." Thesis, University of Bath, 1996. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296332.
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Liaščukienė, Irma. "Lipidų sluoksniai ant nanostruktūrizuoto aliuminio: formavimosi mechanizmas, stabilumas ir įtaka paviršiaus savybėms." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2014. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2014~D_20140722_081312-46485.
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Riebalų rūgščių (RR) gebėjimas sudaryti savitvarkius sluoksnius ant neorganinių medžiagų yra tinkams būdas kontroliuoti paviršių vilgumo savybes. Adsorbcijos mechanimai ant lygių paviršių yra plačiai išnagrinėti, tačiau tarppaviršiniai procesai ant nanostruktūrizuotų paviršių išlieka neaiškūs.
Šiame darbe buvo nagrinėjamas RR bei metilo oleato savitvarkių sluoksnių ant Al oksi-hidroksido formavimosi mechanizmas. PM-RAIRS spektrai parodė, kad RR stipriai sąveikauja su hidroksilinto aliuminio paviršiumi per deprotonizuotas karboksilines grupes. Metilo oleato atveju dėl sąveikos metu vykstančios cheminės transformacijos (muilinimo-hidrolizės) esterio grupė persiformuoja į karboksilatų grupes. Atominės jėgos mikroskopijos pagalba buvo nustatytas paviršiaus morfologijos pokytis - ryškiai matomi reguliarūs linijiniai nanosegmentai, turintys panašius išmatavimus ir tarpusavio atstumus, kurie atsiranda išimtinai dėl riebalų rūgščių savitvarkos.
Savitvarkių sluoksnių stabilumas ir vilgumo ypatybės buvo nagrinėjamos po UV/O3 poveikio, sendinimo ore bei kondicionavimo įvariose vandeninėse terpėse, atsižvelgiant į paviršiaus šiurkštį ir cheminę sudėtį. Darbe pateikti rezultatai rodo, kad aiškios koreliacijos tarp vandens drėkinimo kampo (θw) bei paviršiaus Wenzel šiurkščio nėra. θw smarkiai išauga didėjant adsorbuotų RR -CHx- grupių skaičiui. Tai leidžia teigti, kad paviršiaus hidrofobiškumą didžia dalimi lemia savitvarkiai RR sluoksniai, o šiurkštis turi tik nedidelę įtaką vilgumui... [toliau žr. visą tekstą]The self-assembly of fatty acids (FA) on the surfaces of inorganic materials is a relevant way to control their wetting properties. While the mechanism of adsorption on model flat substrate is well described in the literature, interfacial processes remain poorly documented on nanostructured surfaces. Investigation of the mechanism of self-assembly of fatty acids (FA) and methyl oleate on an Al oxy-hydroxide surface was done. After the FA adsorption, the presence of coordinative bonded carboxylate species on the Al oxy-hydroxide surface is demonstrated by means of PM-IRRAS analysis. The contact of methyl oleate with the surface leads to its chemical transformation through a saponification-hydrolysis reaction. As a consequence, it binds to the surface in a manner similar to that for fatty acids. AFM demonstrated the change of morphology - the existence of highly ordered nanostructures, the formation of aligned nano-patterns, guided only by the FA self-assembly. The stability and the origin of wetting properties of the self-assembled layers was examined under UV/O3 treatment, in air and in aqueous media taking into account key parameters, namely the surface roughness and its composition. Results revealed that no correlation can be made between water contact angles and the Wenzel roughness. By contrast, water contact angle strongly increased with the amount of -CHx- groups exhibited by adsorbed FA. These findings suggest that the main origin of hydrophobisation is the presence... [to full text]
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Hammam, Hagar. "Lipids in supercritical carbon dioxide physical functional aspects /." Lund : Dept. of Food Technology, University of Lund, 1994. http://catalog.hathitrust.org/api/volumes/oclc/39158186.html.
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