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Sample records for lipid layer determined

  1. S-layer-supported lipid membranes.

    PubMed

    Schuster, B; Sleytr, U B

    2000-09-01

    Many prokaryotic organisms (archaea and bacteria) are covered by a regularly ordered surface layer (S-layer) as the outermost cell wall component. S-layers are built up of a single protein or glycoprotein species and represent the simplest biological membrane developed during evolution. Pores in S-layers are of regular size and morphology, and functional groups on the protein lattice are aligned in well-defined positions and orientations. Due to the high degree of structural regularity S-layers represent unique systems for studying the structure, morphogenesis, and function of layered supramolecular assemblies. Isolated S-layer subunits of numerous organisms are able to assemble into monomolecular arrays either in suspension, at air/water interfaces, on planar mono- and bilayer lipid films, on liposomes and on solid supports (e.g. silicon wafers). Detailed studies on composite S-layer/lipid structures have been performed with Langmuir films, freestanding bilayer lipid membranes, solid supported lipid membranes, and liposomes. Lipid molecules in planar films and liposomes interact via their head groups with defined domains on the S-layer lattice. Electrostatic interactions are the most prevalent forces. The hydrophobic chains of the lipid monolayers are almost unaffected by the attachment of the S-layer and no impact on the hydrophobic thickness of the membranes has been observed. Upon crystallization of a coherent S-layer lattice on planar and vesicular lipid membranes, an increase in molecular order is observed, which is reflected in a decrease of the membrane tension and an enhanced mobility of probe molecules within an S-layer-supported bilayer. Thus, the terminology 'semifluid membrane' has been introduced for describing S-layer-supported lipid membranes. The most important feature of composite S-layer/lipid membranes is an enhanced stability in comparison to unsupported membranes. PMID:11143799

  2. Composite S-layer lipid structures.

    PubMed

    Schuster, Bernhard; Sleytr, Uwe B

    2009-10-01

    Designing and utilization of biomimetic membrane systems generated by bottom-up processes is a rapidly growing scientific and engineering field. Elucidation of the supramolecular construction principle of archaeal cell envelopes composed of S-layer stabilized lipid membranes led to new strategies for generating highly stable functional lipid membranes at meso- and macroscopic scale. In this review, we provide a state of the art survey how S-layer proteins, lipids, and polysaccharides may be used as basic building blocks for the assembly of S-layer supported lipid membranes. These biomimetic membrane systems are distinguished by a nanopatterned fluidity, enhanced stability and longevity and thus, provide a dedicated reconstitution matrix for membrane-active peptides and transmembrane proteins. Exciting areas for application of composite S-layer membrane systems concern sensor systems involving specific membrane functions. PMID:19303933

  3. Composite S-layer lipid structures

    PubMed Central

    Schuster, Bernhard; Sleytr, Uwe B.

    2010-01-01

    Designing and utilization of biomimetic membrane systems generated by bottom-up processes is a rapidly growing scientific and engineering field. Elucidation of the supramolecular construction principle of archaeal cell envelopes composed of S-layer stabilized lipid membranes led to new strategies for generating highly stable functional lipid membranes at meso- and macroscopic scale. In this review, we provide a state of the art survey how S-layer proteins, lipids, and polysaccharides may be used as basic building blocks for the assembly of S-layer supported lipid membranes. These biomimetic membrane systems are distinguished by a nanopatterned fluidity, enhanced stability and longevity and thus, provide a dedicated reconstitution matrix for membrane-active peptides and transmembrane proteins. Exciting areas for application of composite S-layer membrane systems concern sensor systems involving specific membrane functions. PMID:19303933

  4. S-layer stabilized lipid membranes (Review)

    PubMed Central

    Schuster, Bernhard; Pum, Dietmar; Sleytr, Uwe B.

    2010-01-01

    The present review focuses on a unique bio-molecular construction kit based on surface-layer (S-layer) proteins as building blocks and patterning elements, but also major classes of biological molecules such as lipids, membrane-active peptides and membrane proteins, and glycans for the design of functional supported lipid membranes. The biomimetic approach copying the supramolecular building principle of most archaeal cell envelopes merely composed of a plasma membrane and a closely associated S-layer lattice has resulted in robust and fluid lipid membranes. Most importantly, S-layer supported lipid membranes spanning an aperture or generated on solid and porous substrates constitute highly interesting model membranes for the reconstitution of responsive transmembrane proteins and membrane-active peptides. This is of particular challenge as one-third of all proteins are membrane proteins such as pore-forming proteins, ion channels, and receptors. S-layer supported lipid membranes are seen as one of the most innovative strategies in membrane protein-based nanobiotechnology with potential applications that range from pharmaceutical (high-throughput) drug screening over lipid chips to the detection of biological warfare agents. PMID:20408666

  5. Control of the morphology of lipid layers by substrate surface chemistry.

    PubMed

    Granqvist, Niko; Yliperttula, Marjo; Välimäki, Salla; Pulkkinen, Petri; Tenhu, Heikki; Viitala, Tapani

    2014-03-18

    In this study, surface coatings were used to control the morphology of the deposited lipid layers during vesicle spreading, i.e., to control if liposomes self-assemble on a surface into a supported lipid bilayer or a supported vesicular layer. The influence of the properties of the surface coating on formation of the deposited lipid layer was studied with quartz crystal microbalance and two-wavelength multiparametric surface plasmon resonance techniques. Control of lipid self-assembly on the surface was achieved by two different types of soft substrate materials, i.e., dextran and thiolated polyethylene glycol, functionalized with hydrophobic linkers for capturing the lipid layer. The low-molecular-weight dextran-based surface promoted formation of supported lipid bilayers, while the thiolated polyethylene glycol-based surface promoted supported vesicular layer formation. A silicon dioxide surface was used as a reference surface in both measurement techniques. In addition to promoting supported lipid bilayer formation of known lipid mixtures, the dextran surface also promoted supported lipid bilayer formation of vesicles containing the cell membrane extract of human hepatoblastoma cells. The new dextran-based surface was also capable of protecting the supported lipid bilayer against dehydration when exposed to a constant flow of air. The well-established quartz crystal microbalance technique was effective in determining the morphology of the formed lipid layer, while the two-wavelength surface plasmon resonance analysis enabled further complementary characterization of the adsorbed supported lipid bilayers and supported vesicular layers. PMID:24564782

  6. Determination of phosphorus in cereal lipids.

    PubMed

    Kovacs, M I

    1986-05-01

    The effect of digestion methods on the determination of phosphorus in cereal lipids was reinvestigated. Samples were either digested with sulfuric acid or ashed in a muffle furnace at 600 degrees C. The standard deviation and the coefficient of variation were significantly higher for the acid-digested samples. Ashing gave more reliable results, especially when large amounts of lipid material had to be oxidized. PMID:3728960

  7. Role of neutral lipids in tear fluid lipid layer: coarse-grained simulation study.

    PubMed

    Telenius, Jelena; Koivuniemi, Artturi; Kulovesi, Pipsa; Holopainen, Juha M; Vattulainen, Ilpo

    2012-12-11

    Tear fluid lipid layer (TFLL) residing at the air-water interface of tears has been recognized to play an important role in the development of dry eye syndrome. Yet, the composition, structure, and mechanical properties of TFLL are only partly known. Here, we report results of coarse-grained simulations of a lipid layer comprising phospholipids, free fatty acids, cholesteryl esters, and triglycerides at the air-water interface to shed light on the properties of TFLL. We consider structural as well as dynamical properties of the lipid layer as a function of surface pressure. Simulations revealed that neutral lipids reside heterogeneously between phospholipids at relatively low pressures but form a separate hydrophobic phase with increasing surface pressure, transforming the initial lipid monolayer to a two-layered structure. When the model of TFLL was compared to a one-component phospholipid monolayer system, we found drastic differences in both structural and dynamical properties that explain the prominent role of neutral lipids as stabilizers of the TFLL. Based on our results, we suggest that neutral lipids are able to increase the stability of the TFLL by modulating its dynamical and structural behavior, which is important for the proper function of tear film. PMID:23151187

  8. Combined urea-thin layer chromatography and silver nitrate-thin layer chromatography for micro separation and determination of hard-to-detect branched chain fatty acids in natural lipids.

    PubMed

    Yan, Yuanyuan; Wang, Xingguo; Liu, Yijun; Xiang, Jingying; Wang, Xiaosan; Zhang, Huijun; Yao, Yunping; Liu, Ruijie; Zou, Xiaoqiang; Huang, Jianhua; Jin, Qingzhe

    2015-12-18

    A simple, fast and efficient procedure was developed for micro separation and enrichment of branched chain fatty acids (BCFA) from natural products using successive thin layer chromatography (TLC) technique coupling novel urea-TLC with AgNO3-TLC, which rely on the formation of urea adduction and AgNO3 bonding in methanol. These natural lipids contain a significant amount of straight chain fatty acids (FA). Fresh and fast urea-TLC and AgNO3-TLC plate making techniques were developed with more even coating and less coating material contamination before being utilized for separation. Goat milk fat was used as a model. Various experimental parameters that affect urea-TLC and AgNO3-TLC separation of BCFA were investigated and optimized, including coating of urea, concentration of original oil sample, mobile phase and sample application format. High efficiency of removal of straight chain FA was achieved with a low amount of sample in an easy and fast way. A total BCFA mix with much higher purity than previous studies was successfully achieved. The developed method has also been applied for the concentration and analysis of BCFA in cow milk fat and Anchovy oil. PMID:26614174

  9. Lipid Layers on Polyelectrolyte Multilayers: Understanding Lipid-Polyelectrolyte Interactions and Applications on the Surface Engineering of Nanomaterials.

    PubMed

    Diamanti, Eleftheria; Gregurec, Danijela; Gabriela, Romero; Cuellar, J L; Donath, E; Moya, S E

    2016-06-01

    In this manuscript we review work of our group on the assembly of lipid layers on top of polyelectrolyte multilayers (PEMs). The assembly of lipid layers with zwitterionic and charged lipids on PEMs is studied as a function of lipid and polyelectrolyte composition by the Quartz Crystal Microbalance. Polyelectrolyte lipid interactions are studied by means of Atomic Force Spectroscopy. We also show the coating of lipid layers for engineering different nanomaterials, i.e., carbon nanotubes and poly(lactic-co-glycolic) nanoparticles and how these can be used to decrease in vitro toxicity and to direct the intracellular localization of nanomaterials. PMID:27427617

  10. Changes in wetting and energetic properties of glass caused by deposition of different lipid layers

    NASA Astrophysics Data System (ADS)

    Gołąbek (Mirosław), Monika; Hołysz, Lucyna

    2010-06-01

    An investigation of wetting and energetic properties of different lipid layers deposited on the glass surface was carried out by contact angles measurements and determination of the apparent surface free energy. The topography of the lipid layers was also determined with the help of atomic force microscopy (AFM). Two synthetic phospholipids were chosen for these studies, having the same phosphatidylcholine headgroup bound to the apolar part composed either by two saturated chains (1,2-dipalmitoyl- sn-glycero-3-phospshocholine - DPPC) or two unsaturated chains (1,2-dioleoyl- sn-glycero-3-phosphocholine - DOPC) and one lipid (1,2,3-trihexadecanoyl- sn-glycerol - tripalmitoylglycerol - TPG). The lipid layers, from the 1st to the 5th statistical monolayer, were deposited on the glass surface from chloroform solutions by spreading. The apparent surface free energy of the deposited layers was determined by contact angles measurements (advancing and receding) for three probe liquids (diiodomethane, water, and formamide), and then two concepts of interfacial interactions were applied. In the contact angle hysteresis approach (CAH) the apparent total surface free energy was calculated from the advancing and receding contact angles and surface tension of probe liquids. In the Lifshitz-van der Waals/acid-base approach (LWAB) the total surface free energy was calculated from the determined components of the energy, which were obtained from the advancing contact angles of the probe liquids only. Comparison of the results obtained by two approaches provided more information about the changes in the hydrophobicity/hydrophilicity of the layers depending on the number of monolayers and kind of the lipid deposited on the glass surface. It was found that the most visible changes in the surface free energy took place for the first two statistical monolayers irrespectively of the kind of the lipid used. Additionally, in all cases periodic oscillations from layer-to-layer in the lipid

  11. Effect of meibomian lipid layer on evaporation of tears

    NASA Astrophysics Data System (ADS)

    Miano, F.; Calcara, M.; Giuliano, F.; Millar, T. J.; Enea, V.

    2004-07-01

    The outer interface of a tear film was studied with the aid of a model system able to investigate the interfacial phenomena derived from the spreading of an insoluble lipid multilayer onto a tear-like aqueous fluid. The interactions of such a layer with proteins dissolved in the aqueous phase beneath were also investigated. Emphasis was given to evaporation phenomena because the increased rate of tear evaporation in humans is often related to a number of ocular dysfunctions. The model tear was studied as a pendant drop that permitted a functional evaluation of the effect of lipids and proteins upon the evaporation of water from the tear film.

  12. Layer-by-Layer Assembly of Supported Lipid Bilayer Poly-L-Lysine Multilayers.

    PubMed

    Heath, George R; Li, Mengqiu; Polignano, Isabelle L; Richens, Joanna L; Catucci, Gianluca; O'Shea, Paul; Sadeghi, Sheila J; Gilardi, Gianfranco; Butt, Julea N; Jeuken, Lars J C

    2016-01-11

    Multilayer lipid membranes perform many important functions in biology, such as electrical isolation (myelination of axons), increased surface area for biocatalytic purposes (thylakoid grana and mitochondrial cristae), and sequential processing (golgi cisternae). Here we develop a simple layer-by-layer methodology to form lipid multilayers via vesicle rupture onto existing supported lipid bilayers (SLBs) using poly l-lysine (PLL) as an electrostatic polymer linker. The assembly process was monitored at the macroscale by quartz crystal microbalance with dissipation (QCM-D) and the nanoscale by atomic force microscopy (AFM) for up to six lipid bilayers. By varying buffer pH and PLL chain length, we show that longer chains (≥300 kDa) at pH 9.0 form thicker polymer supported multilayers, while at low pH and shorter length PLL, we create close packed layers (average lipid bilayers separations of 2.8 and 0.8 nm, respectively). Fluorescence recovery after photobleaching (FRAP) and AFM were used to show that the diffusion of lipid and three different membrane proteins in the multilayered membranes has little dependence on lipid stack number or separation between membranes. These approaches provide a straightforward route to creating the complex membrane structures that are found throughout nature, allowing possible applications in areas such as energy production and biosensing while developing our understanding of the biological processes at play. PMID:26642374

  13. Tear film lipid layer: A molecular level view.

    PubMed

    Cwiklik, Lukasz

    2016-10-01

    Human cornea is covered by an aqueous tear film, and the outermost layer of the tear film is coated by lipids. This so-called tear film lipid layer (TFLL) reduces surface tension of the tear film and helps with the film re-spreading after blinks. Alterations of tear lipids composition and properties are related to dry eye syndrome. Therefore, unveiling structural and functional properties of TFLL is necessary for understanding tear film function under both normal and pathological conditions. Key properties of TFLL, such as resistance against high lateral pressures and ability to spread at the tear film surface, are directly related to the chemical identity of TFLL lipids. Hence, a molecular-level description is required to get better insight into TFLL properties. Molecular dynamics simulations are particularly well suited for this task and they were recently used for investigating TFLL. The present review discusses molecular level organization and properties of TFLL as seen by these simulation studies. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg. PMID:26898663

  14. Criteria for lipid layer pattern evaluation: Pli-marker database

    NASA Astrophysics Data System (ADS)

    García-Resúa, Carlos; Pena-Verdeal, Hugo; Remeseiro, Beatriz; Penedo, Manuel G.; Giráldez, María. Jesús; Yebra-Pimentel, Eva

    2013-11-01

    The purpose of this study is to establish the procedure of acquisition and evaluate the Lipid layer pattern (LLP) by Tearscope in order to enhance this useful technique. To aid this purpose, we present a new broad LLP images database (included in a web application called Pli-marker) The tear film lipid layer was examined using a Tearscope-plus (Keeler, Windsor, UK). To capture LLPs videos a Topcon DV-3 digital camera was used and attached to the slit lamp. All videos were stored in a computer via Topcon IMAGEnet i-base software and LLP images were obtained and uploaded at Pli-marker web application, which offers the manual selection of regions associated to a specific LLP. 50 images were analysed by 4 experienced optometrists. Each of them marked (using Pli-marker) those areas in the 50 images that corresponded with some of the 5 LLP: open meshwork (OM), closed meshwork, (CM), wave (W), amorphous (AM) and color fringe (CO). From the 50 images we obtained 25 areas of OM, 22 areas of CM, 20 areas of W, 46 areas of AM and 17 areas of CO that 4 observers were in accordance. We present an example of 4 pictures for each area of concordance together with the description of the features used for categorizing the LLP in our study. This work describes the methodology used in our research project, including settings for capture image, and the criteria for subjective categorization of the LLP accomplished by a set of images.

  15. Profiling the triacylglyceride contents in bat integumentary lipids by preparative thin layer chromatography and MALDI-TOF mass spectrometry.

    PubMed

    Pannkuk, Evan L; Risch, Thomas S; Savary, Brett J

    2013-01-01

    The mammalian integument includes sebaceous glands that secrete an oily material onto the skin surface. Sebum production is part of the innate immune system that is protective against pathogenic microbes. Abnormal sebum production and chemical composition are also a clinical symptom of specific skin diseases. Sebum contains a complex mixture of lipids, including triacylglycerides, which is species-specific. The broad chemical properties exhibited by diverse lipid classes hinder the specific determination of sebum composition. Analytical techniques for lipids typically require chemical derivatizations that are labor-intensive and increase sample preparation costs. This paper describes how to extract lipids from mammalian integument, separate broad lipid classes by thin-layer chromatography, and profile the triacylglyceride contents using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. This robust method enables a direct determination of the triacylglyceride profiles among species and individuals, and it can be readily applied to any taxonomic group of mammals. PMID:24056580

  16. Profiling the Triacylglyceride Contents in Bat Integumentary Lipids by Preparative Thin Layer Chromatography and MALDI-TOF Mass Spectrometry

    PubMed Central

    Pannkuk, Evan L.; Risch, Thomas S.; Savary, Brett J.

    2013-01-01

    The mammalian integument includes sebaceous glands that secrete an oily material onto the skin surface. Sebum production is part of the innate immune system that is protective against pathogenic microbes. Abnormal sebum production and chemical composition are also a clinical symptom of specific skin diseases. Sebum contains a complex mixture of lipids, including triacylglycerides, which is species-specific. The broad chemical properties exhibited by diverse lipid classes hinder the specific determination of sebum composition. Analytical techniques for lipids typically require chemical derivatizations that are labor-intensive and increase sample preparation costs. This paper describes how to extract lipids from mammalian integument, separate broad lipid classes by thin-layer chromatography, and profile the triacylglyceride contents using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. This robust method enables a direct determination of the triacylglyceride profiles among species and individuals, and it can be readily applied to any taxonomic group of mammals. PMID:24056580

  17. Tear lipid layer deficiency associated with incomplete blinking: A case report

    PubMed Central

    2013-01-01

    Background Meibomian gland obstruction induces hyposecretion of tear film lipids, which results in lipid layer deficiency and evaporative dry eye. Unfortunately, the importance of blinking in meibomian gland dysfunction has been largely overlooked, and it is not known whether incomplete blinking causes tear lipid deficiency, even in the unobstructed meibomian glands. Case presentation A 38-year-old woman suffering from foreign body sensations in her eyes was examined. The cornea was clear and tear secretion was normal. Lid margin abnormalities were not observed and the meibum was clear. However, the lipid layer was very thin, and the patient was given a diagnosis of incomplete blinking. The patient was made aware of her condition and asked to blink consciously and completely. After that, an immediate increase in lipid flow was observed. Conclusion Tear lipid layer deficiency can occur with incomplete blinking, even though meibomian gland structures are intact. This case highlights the importance of complete blinking. PMID:23855887

  18. Early determinants of development: a lipid perspective1234

    PubMed Central

    Carlson, Susan E

    2009-01-01

    This article results from an International Life Sciences Institute workshop on early nutritional determinants of health and development. The presentation on lipids focused mainly on the longer-chain products of the essential fatty acids, particularly docosahexaenoic acid (22:6n–3), and cognitive development as among the most studied lipids and outcomes, respectively, in early human nutrition. Because there have been several recent reviews on this topic, the present review takes a broader perspective with respect to both early development and lipids: an expanded research agenda is plausible on the basis of observations from some human studies and from animal studies. Other lipids known to be provided in variable amounts to infants through human milk are cholesterol and gangliosides. Short sections address the current state of knowledge and some questions that could be pursued. PMID:19321568

  19. Ionic conductivity of the aqueous layer separating a lipid bilayer membrane and a glass support.

    PubMed

    White, Ryan J; Zhang, Bo; Daniel, Susan; Tang, John M; Ervin, Eric N; Cremer, Paul S; White, Henry S

    2006-12-01

    The in-plane ionic conductivity of the approximately 1-nm-thick aqueous layer separating a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) bilayer membrane and a glass support was investigated. The aqueous layer conductivity was measured by tip-dip deposition of a POPC bilayer onto the surface of a 20- to 75-microm-thick glass membrane containing a single conical-shaped nanopore and recording the current-voltage (i-V) behavior of the glass membrane nanopore/POPC bilayer structure. The steady-state current across the glass membrane passes through the nanopore (45-480 nm radius) and spreads radially outward within the aqueous layer between the glass support and bilayer. This aqueous layer corresponds to the dominant resistance of the glass membrane nanopore/POPC bilayer structure. Fluorescence recovery after photobleaching measurements using dye-labeled lipids verified that the POPC bilayer maintains a significant degree of fluidity on the glass membrane. The slopes of ohmic i-V curves yield an aqueous layer conductivity of (3 +/- 1) x 10(-3) Omega(-1) cm(-1) assuming a layer thickness of 1.0 nm. This conductivity is essentially independent of the concentration of KCl in the bulk solution (10-4 to 1 M) in contact with the membrane. The results indicate that the concentration and mobility of charge carriers in the aqueous layer between the glass support and bilayer are largely determined by the local structure of the glass/water/bilayer interface. PMID:17129059

  20. Determining the pivotal plane of fluid lipid membranes in simulations.

    PubMed

    Wang, Xin; Deserno, Markus

    2015-10-28

    Each leaflet of a curved lipid membrane contains a surface at which the area strain vanishes, the so-called pivotal plane. Its distance z0 from the bilayer's midplane arises in numerous contexts, for instance the connection between monolayer and bilayer moduli, stress-profile moments, or area-difference elasticity theories. Here, we propose two precise methods for determining the location of the pivotal plane in computer simulations, both of which rely on monitoring the lipid imbalance across a curved bilayer. The first method considers the ratio of lipid number between the two leaflets of cylindrical or spherical vesicles; it hence requires lipid flip-flop for equilibration. The second method looks at the leaflet difference across local sections cut out from a buckled membrane; this observable equilibrates even in the absence of flip-flop. We apply our methods to two different coarse-grained lipid models, the generic three-bead solvent-free Cooke model and a ten-bead representation of dimyristoylphosphocholine with the explicit solvent MARTINI model. The Cooke model is amenable to both methods and gives results that agree at the percent level. Using it, we also show that the pivotal plane moves outward as lipid curvature becomes more positive. The MARTINI model can only be analyzed with the buckling method; the obtained value z0 = 0.850(11) nm lies about 0.4 nm inwards of the glycerol backbone and is hence unexpectedly small. We attribute this to limitations of the coarse-grained description, suggesting that the location of the pivotal plane might be a good indicator for how well lipid models capture the microscopic origins of curvature elasticity. Finally, we also show that the pivotal plane position itself moves as the membrane is bent. The leading correction is linear in curvature, dependent on the Poisson ratio, and can matter when analyzing experimental results obtained from highly curved inverse hexagonal phases. PMID:26520500

  1. Determining the pivotal plane of fluid lipid membranes in simulations

    NASA Astrophysics Data System (ADS)

    Wang, Xin; Deserno, Markus

    2015-10-01

    Each leaflet of a curved lipid membrane contains a surface at which the area strain vanishes, the so-called pivotal plane. Its distance z0 from the bilayer's midplane arises in numerous contexts, for instance the connection between monolayer and bilayer moduli, stress-profile moments, or area-difference elasticity theories. Here, we propose two precise methods for determining the location of the pivotal plane in computer simulations, both of which rely on monitoring the lipid imbalance across a curved bilayer. The first method considers the ratio of lipid number between the two leaflets of cylindrical or spherical vesicles; it hence requires lipid flip-flop for equilibration. The second method looks at the leaflet difference across local sections cut out from a buckled membrane; this observable equilibrates even in the absence of flip-flop. We apply our methods to two different coarse-grained lipid models, the generic three-bead solvent-free Cooke model and a ten-bead representation of dimyristoylphosphocholine with the explicit solvent MARTINI model. The Cooke model is amenable to both methods and gives results that agree at the percent level. Using it, we also show that the pivotal plane moves outward as lipid curvature becomes more positive. The MARTINI model can only be analyzed with the buckling method; the obtained value z0 = 0.850(11) nm lies about 0.4 nm inwards of the glycerol backbone and is hence unexpectedly small. We attribute this to limitations of the coarse-grained description, suggesting that the location of the pivotal plane might be a good indicator for how well lipid models capture the microscopic origins of curvature elasticity. Finally, we also show that the pivotal plane position itself moves as the membrane is bent. The leading correction is linear in curvature, dependent on the Poisson ratio, and can matter when analyzing experimental results obtained from highly curved inverse hexagonal phases.

  2. Four Characteristics and a Model of an Effective Tear Film Lipid Layer (TFLL)

    PubMed Central

    King-Smith, P. Ewen; Bailey, Melissa D.; Braun, Richard J.

    2015-01-01

    It is proposed that a normal, effective tear film lipid layer (TFLL) should have the following four characteristics: 1) high evaporation resistance to prevent water loss and consequent hyperosmolarity; 2) respreadability, so it will return to its original state after the compression-expansion cycle of the blink; 3) fluidity sufficient to avoid blocking secretion from meibomian glands; 4) gel-like and incompressible structure that can resist forces that may tend to disrupt it. These characteristics tend to be incompatible; for example, lipids that form good evaporation barriers tend to be disrupted by compression-expansion cycles. It is noted that clues about the function and organization of the TFLL can be obtained by comparison with other biological lipid layers, such as lung surfactant and the lipid evaporation barrier of the skin. In an attempt to satisfy the conflicting characteristics, a “multilamellar sandwich model” of the TFLL is proposed, having features in common with the skin evaporation barrier. PMID:24112227

  3. Biophysical investigations of the structure and function of the tear fluid lipid layers and the effect of ectoine. Part B: artificial lipid films.

    PubMed

    Dwivedi, Mridula; Brinkkötter, Marc; Harishchandra, Rakesh Kumar; Galla, Hans-Joachim

    2014-10-01

    The tear fluid lipid layer is present at the outermost part of the tear film which lines the ocular surface and functions to maintain the corneal surface moist by retarding evaporation. Instability in the structure of the tear fluid lipid layer can cause an increased rate of evaporation and thus dry eye syndrome. Ectoine has been previously shown to fluidize lipid monolayers and alter the phase behavior. In the current study we have investigated the effect of ectoine on the artificial tear fluid lipid layer composed of binary and ternary lipid mixtures of dipalmitoyl phosphatidylcholine (DPPC), cholesteryl esters and tri-acyl-glycerols. The focus of our study was mainly the structural and the biophysical aspects of the artificial tear fluid lipid layer using surface activity studies and topology analysis. The presence of ectoine consistently causes an expansion of the pressure-area isotherm indicating increased intermolecular spacing. The topology studies showed the formation of droplet-like structures due to the addition of ectoine only when tri-acyl-glycerol is present in the mixture of DPPC and chol-palmitate, similar to the natural meibomian lipids. Consequently, the hypothesis of an exclusion of tri/di-acyl-glycerol from the meibomian lipid film in the presence of ectoine in the subphase is confirmed. A model describing the effect of ectoine on meibomian lipid films is further presented which may have an application for the use of ectoines in eye drops as a treatment for the dry eye syndrome. PMID:24853656

  4. Biomimetic interfaces based on S-layer proteins, lipid membranes and functional biomolecules

    PubMed Central

    Schuster, Bernhard; Sleytr, Uwe B.

    2014-01-01

    Designing and utilization of biomimetic membrane systems generated by bottom-up processes is a rapidly growing scientific and engineering field. Elucidation of the supramolecular construction principle of archaeal cell envelopes composed of S-layer stabilized lipid membranes led to new strategies for generating highly stable functional lipid membranes at meso- and macroscopic scale. In this review, we provide a state-of-the-art survey of how S-layer proteins, lipids and polymers may be used as basic building blocks for the assembly of S-layer-supported lipid membranes. These biomimetic membrane systems are distinguished by a nanopatterned fluidity, enhanced stability and longevity and, thus, provide a dedicated reconstitution matrix for membrane-active peptides and transmembrane proteins. Exciting areas in the (lab-on-a-) biochip technology are combining composite S-layer membrane systems involving specific membrane functions with the silicon world. Thus, it might become possible to create artificial noses or tongues, where many receptor proteins have to be exposed and read out simultaneously. Moreover, S-layer-coated liposomes and emulsomes copying virus envelopes constitute promising nanoformulations for the production of novel targeting, delivery, encapsulation and imaging systems. PMID:24812051

  5. Lipids from the nacreous and prismatic layers of two Pteriomorpha Mollusc shells

    NASA Astrophysics Data System (ADS)

    Farre, B.; Dauphin, Y.

    2009-04-01

    Mollusc shells are the best-known Ca-carbonate biominerals. They are commonly described as a mineralized two layered structure: an outer layer composed of calcite prismatic units, and an internal layer composed of tablets of aragonite: the nacreous layer. An external organic layer (periostracum) is present in most taxa. However, the most common structure in the Mollusc shell is the aragonite crossed lamellar layer, but aragonite prisms, calcite foliated layers and homogeneous layers have been also described by Boggild (1930) in all the Mollusc orders. Since, more detailed descriptions of Bivalve shells have been done (Taylor et al., 1969, 1973). Despite the nacroprismatic arrangement is rare, calcite prismatic and aragonite nacreous layers are the best studied because of their simple 3D structure and large units. Among these Molluscs, some Bivalve species composed of these two layers are of commercial interest, such as the pearl oyster, Pinctada margaritifera, cultivated in French Polynesia to produce black pearls. It is well established that Mollusc shells are composite structures of organic and inorganic components (Hatchett, 1799; Grégoire et al., 1955; Beedham, 1958; Simkiss, 1965; Mutvei, 1969; Cuif et al., 1980; Berman et al., 1993; Kobayashi and Samata, 2006). Numerous studies are concerned with the organic matrix of the shell. Organic components are commonly obtained after a strong or mild decalcification process. They are said to consist of both a soluble and insoluble fraction. The main part of studies is dedicated to the soluble components, and among them, proteins (Grégoire et al., 1955; Grégoire, 1961; Krampitz et al., 1976; Samata et al., 1980, 2004; Weiner, 1983; Miyamoto et al., 2006). Despite the pioneering work of Wada (1980) sugars are usually neglected despite their role in biomineralization. The third component of the organic matrix of calcareous biominerals is lipids. To date, there is a paucity of information concerning the presence

  6. Lipid analysis by thin-layer chromatography--a review of the current state.

    PubMed

    Fuchs, Beate; Süss, Rosmarie; Teuber, Kristin; Eibisch, Mandy; Schiller, Jürgen

    2011-05-13

    High-performance thin-layer chromatography (HPTLC) is a widely used, fast and relatively inexpensive method of separating complex mixtures. It is particularly useful for smaller, apolar compounds and offers some advantages over HPLC. This review gives an overview about the special features as well as the problems that have to be considered upon the HPTLC analysis of lipids. The term "lipids" is used here in a broad sense and comprises fatty acids and their derivatives as well as substances related biosynthetically or functionally to these compounds. After a short introduction regarding the stationary phases and the methods how lipids can be visualized on an HPTLC plate, the individual lipid classes will be discussed and the most suitable solvent systems for their separation indicated. The focus will be on lipids that are most abundant in biological systems, i.e. cholesterol and its derivates, glycerides, sphingo- and glycolipids as well as phospholipids. Finally, a nowadays very important topic, the combination between HPTLC and mass spectrometric (MS) detection methods will be discussed. It will be shown that this is a very powerful method to investigate the identities of the HPTLC spots in more detail than by the use of common staining methods. Future aspects of HPTLC in the lipid field will be also discussed. PMID:21167493

  7. DIRECT DETERMINATION OF THE LIPID CONTENT IN STARCH-LIPID COMPOSITES BY TIME-DOMAIN NMR

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Starch-lipid composites, prepared by excess steam jet-cooking aqueous mixtures of starch and lipid, are used in various applications for which their performance can depend upon accurate quantitation of lipid contained within these composites. A rapid and non-destructive method based on time-domain ...

  8. Lipids from the nacreous and prismatic layers of two Pteriomorpha Mollusc shells

    NASA Astrophysics Data System (ADS)

    Farre, B.; Dauphin, Y.

    2009-04-01

    Mollusc shells are the best-known Ca-carbonate biominerals. They are commonly described as a mineralized two layered structure: an outer layer composed of calcite prismatic units, and an internal layer composed of tablets of aragonite: the nacreous layer. An external organic layer (periostracum) is present in most taxa. However, the most common structure in the Mollusc shell is the aragonite crossed lamellar layer, but aragonite prisms, calcite foliated layers and homogeneous layers have been also described by Boggild (1930) in all the Mollusc orders. Since, more detailed descriptions of Bivalve shells have been done (Taylor et al., 1969, 1973). Despite the nacroprismatic arrangement is rare, calcite prismatic and aragonite nacreous layers are the best studied because of their simple 3D structure and large units. Among these Molluscs, some Bivalve species composed of these two layers are of commercial interest, such as the pearl oyster, Pinctada margaritifera, cultivated in French Polynesia to produce black pearls. It is well established that Mollusc shells are composite structures of organic and inorganic components (Hatchett, 1799; Grégoire et al., 1955; Beedham, 1958; Simkiss, 1965; Mutvei, 1969; Cuif et al., 1980; Berman et al., 1993; Kobayashi and Samata, 2006). Numerous studies are concerned with the organic matrix of the shell. Organic components are commonly obtained after a strong or mild decalcification process. They are said to consist of both a soluble and insoluble fraction. The main part of studies is dedicated to the soluble components, and among them, proteins (Grégoire et al., 1955; Grégoire, 1961; Krampitz et al., 1976; Samata et al., 1980, 2004; Weiner, 1983; Miyamoto et al., 2006). Despite the pioneering work of Wada (1980) sugars are usually neglected despite their role in biomineralization. The third component of the organic matrix of calcareous biominerals is lipids. To date, there is a paucity of information concerning the presence

  9. Probing peptide and protein insertion in a biomimetic S-layer supported lipid membrane platform.

    PubMed

    Damiati, Samar; Schrems, Angelika; Sinner, Eva-Kathrin; Sleytr, Uwe B; Schuster, Bernhard

    2015-01-01

    The most important aspect of synthetic lipid membrane architectures is their ability to study functional membrane-active peptides and membrane proteins in an environment close to nature. Here, we report on the generation and performance of a biomimetic platform, the S-layer supported lipid membrane (SsLM), to investigate the structural and electrical characteristics of the membrane-active peptide gramicidin and the transmembrane protein α-hemolysin in real-time using a quartz crystal microbalance with dissipation monitoring in combination with electrochemical impedance spectroscopy. A shift in membrane resistance is caused by the interaction of α-hemolysin and gramicidin with SsLMs, even if only an attachment onto, or functional channels through the lipid membrane, respectively, are formed. Moreover, the obtained results did not indicate the formation of functional α-hemolysin pores, but evidence for functional incorporation of gramicidin into this biomimetic architecture is provided. PMID:25633104

  10. Characterization of Floating Surface Layers of Lipids and Lipopolymers by Surface-Sensitive Scattering

    NASA Astrophysics Data System (ADS)

    Krüger, Peter; Lösche, Mathias

    Nanotechnology and molecular (bio-)engineering are making ever deepening inroads into everybodys daily life. Physicochemical and biotechnological achievements in the design of physiologically active supramolecular assemblies have brought about the quest for their submolecular-level characterization. We employ surface-sensitive scattering techniques for the investigation of planar lipid membranes - floating monolayers on aqueous surfaces - to correlate structural, functional and dynamic aspects of biomembrane models. This chapter surveys recent work on the submolecular structure of floating phospholipid monolayers - where the advent of third-generation synchrotron X-ray sources has driven the development of realistic, submolecular-scale quasi-chemical models - as well as of more complex systems: cation binding to anionic lipid surfaces; conformational changes of lipopolymers undergoing phase transitions; the conformational organization of phosphatidylinositol and phosphatidylinositides, as examples of physiologically important lipids; and the adsorption of peptides (neuropeptide Y, NPY) or solvents (dimethylsulfoxide, DMSO) onto phospholipid surface layers.

  11. Probing Peptide and Protein Insertion in a Biomimetic S-Layer Supported Lipid Membrane Platform

    PubMed Central

    Damiati, Samar; Schrems, Angelika; Sinner, Eva-Kathrin; Sleytr, Uwe B.; Schuster, Bernhard

    2015-01-01

    The most important aspect of synthetic lipid membrane architectures is their ability to study functional membrane-active peptides and membrane proteins in an environment close to nature. Here, we report on the generation and performance of a biomimetic platform, the S-layer supported lipid membrane (SsLM), to investigate the structural and electrical characteristics of the membrane-active peptide gramicidin and the transmembrane protein α-hemolysin in real-time using a quartz crystal microbalance with dissipation monitoring in combination with electrochemical impedance spectroscopy. A shift in membrane resistance is caused by the interaction of α-hemolysin and gramicidin with SsLMs, even if only an attachment onto, or functional channels through the lipid membrane, respectively, are formed. Moreover, the obtained results did not indicate the formation of functional α-hemolysin pores, but evidence for functional incorporation of gramicidin into this biomimetic architecture is provided. PMID:25633104

  12. Thermal stability of ladderane lipids as determined by hydrous pyrolysis

    USGS Publications Warehouse

    Jaeschke, A.; Lewan, M.D.; Hopmans, E.C.; Schouten, S.; Sinninghe, Damste J.S.

    2008-01-01

    Anaerobic ammonium oxidation (anammox) has been recognized as a major process resulting in loss of fixed inorganic nitrogen in the marine environment. Ladderane lipids, membrane lipids unique to anammox bacteria, have been used as markers for the detection of anammox in marine settings. However, the fate of ladderane lipids after sediment burial and maturation is unknown. In this study, anammox bacterial cell material was artificially matured by hydrous pyrolysis at constant temperatures ranging from 120 to 365 ??C for 72 h to study the stability of ladderane lipids during progressive dia- and catagenesis. HPLC-MS/MS analysis revealed that structural alterations of ladderane lipids already occurred at 120 ??C. At temperatures >140 ??C, ladderane lipids were absent and only more thermally stable products could be detected, i.e., ladderane derivatives in which some of the cyclobutane rings were opened. These diagenetic products of ladderane lipids were still detectable up to temperatures of 260 ??C using GC-MS. Thus, ladderane lipids are unlikely to occur in ancient sediments and sedimentary rocks, but specific diagenetic products of ladderane lipids will likely be present in sediments and sedimentary rocks of relatively low maturity (i.e., C31 hopane 22S/(22S + 22R) ratio 0.5). ?? 2008 Elsevier Ltd.

  13. Spectroscopic study of 3-Hydroxyflavone - protein interaction in lipidic bi-layers immobilized on silver nanoparticles.

    PubMed

    Voicescu, Mariana; Ionescu, Sorana; Nistor, Cristina L

    2017-01-01

    The interaction of 3-Hydroxyflavone with serum proteins (BSA and HSA) in lecithin lipidic bi-layers (PC) immobilized on silver nanoparticles (SNPs), was studied by fluorescence and Raman spectroscopy. BSA secondary structure was quantified with a deconvolution algorithm, showing a decrease in α-helix structure when lipids were added to the solution. The effect of temperature on the rate of the excited-state intra-molecular proton transfer and on the dual fluorescence emission of 3-HF in the HSA/PC/SNPs systems was discussed. Evaluation of the antioxidant activity of 3-HF in HSA/PC/SNPs systems was also studied. The antioxidant activity of 3-HF decreased in the presence of SNPs. The results are discussed with relevance to the secondary structure of proteins and of the 3-HF based nano-systems to a topical formulation useful in the oxidative stress process. PMID:27380623

  14. Intraspecific Differences in Lipid Content of Calanoid Copepods across Fine-Scale Depth Ranges within the Photic Layer

    PubMed Central

    Zarubin, Margarita; Farstey, Viviana; Wold, Anette; Falk-Petersen, Stig; Genin, Amatzia

    2014-01-01

    Copepods are among the most abundant and diverse groups of mesozooplankton in the world's oceans. Each species has a certain depth range within which different individuals (of the same life stage and sex) are found. Lipids are accumulated in many calanoid copepods for energy storage and reproduction. Lipid content in some species increases with depth, however studies so far focused mostly on temperate and high-latitude seasonal vertically migrating copepods and compared lipid contents among individuals either from coarse layers or between diapausing, deep-dwelling copepods and individuals found in the photic, near-surface layer. Here we examined whether lipid contents of individual calanoid copepods of the same species, life stage/sex differ between finer depth layers within the upper water column of subtropical and Arctic seas. A total of 6 calanoid species were collected from samples taken at precise depths within the photic layer in both cold eutrophic and warm oligotrophic environments using SCUBA diving, MOCNESS and Multinet. Measurements of lipid content were obtained from digitized photographs of the collected individuals. The results revealed significant differences in lipid content across depth differences as small as 12–15 meters for Mecynocera clausi C5 and Ctenocalanus vanus C5 (Red Sea), Clausocalanus furcatus males and two clausocalanid C5s (Mediterranean Sea), and Calanus glacialis C5 (Arctic). We suggest two possible explanations for the differences in lipid content with depth on such a fine scale: predator avoidance and buoyancy. PMID:24667529

  15. Intraspecific differences in lipid content of calanoid copepods across fine-scale depth ranges within the photic layer.

    PubMed

    Zarubin, Margarita; Farstey, Viviana; Wold, Anette; Falk-Petersen, Stig; Genin, Amatzia

    2014-01-01

    Copepods are among the most abundant and diverse groups of mesozooplankton in the world's oceans. Each species has a certain depth range within which different individuals (of the same life stage and sex) are found. Lipids are accumulated in many calanoid copepods for energy storage and reproduction. Lipid content in some species increases with depth, however studies so far focused mostly on temperate and high-latitude seasonal vertically migrating copepods and compared lipid contents among individuals either from coarse layers or between diapausing, deep-dwelling copepods and individuals found in the photic, near-surface layer. Here we examined whether lipid contents of individual calanoid copepods of the same species, life stage/sex differ between finer depth layers within the upper water column of subtropical and Arctic seas. A total of 6 calanoid species were collected from samples taken at precise depths within the photic layer in both cold eutrophic and warm oligotrophic environments using SCUBA diving, MOCNESS and Multinet. Measurements of lipid content were obtained from digitized photographs of the collected individuals. The results revealed significant differences in lipid content across depth differences as small as 12-15 meters for Mecynocera clausi C5 and Ctenocalanus vanus C5 (Red Sea), Clausocalanus furcatus males and two clausocalanid C5s (Mediterranean Sea), and Calanus glacialis C5 (Arctic). We suggest two possible explanations for the differences in lipid content with depth on such a fine scale: predator avoidance and buoyancy. PMID:24667529

  16. Phospatidylserine or ganglioside--which of anionic lipids determines the effect of cationic dextran on lipid membrane?

    PubMed

    Hąc-Wydro, Katarzyna; Wydro, Paweł; Cetnar, Andrzej; Włodarczyk, Grzegorz

    2015-02-01

    In this work the influence of cationic polymer, namely diethylaminoethyl DEAE-dextran on model lipid membranes was investigated. This polymer is of a wide application as a biomaterial and a drug carrier and its cytotoxicity toward various cancer cells was also confirmed. It was suggested that anticancer effect of cationic dextran is connected with the binding of the polymer to the negatively charged sialic acid residues overexpressed in cancer membrane. This fact encouraged us to perform the studies aimed at verifying whether the effect of cationic DEAE-dextran on membrane is determined only by the presence of the negatively charged lipid in the system or the kind of anionic lipid is also important. To reach this goal systematic investigations on the effect of dextran on various one-component lipid monolayers and multicomponent hepatoma cell model membranes differing in the level and the kind of anionic lipids (phosphatidylserine, sialic acid-containing ganglioside GM3 or their mixture) were done. As evidenced the results the effect of DEAE-dextran on the model system is determined by anionic lipid-polymer electrostatic interactions. However, the magnitude of the effect of cationic polymer is strongly dependent on the kind of anionic lipid in the model system. Namely, the packing and ordering of the mixtures containing ganglioside GM3 were more affected by DEAE-dextran than phosphatidylserine-containing monolayers. Although the experiments were done on model systems and therefore further studies are highly needed, the collected data may indicate that ganglioside may be important in the differentiation of the effect of cationic dextran on membranes. PMID:25576813

  17. The Cincinnati Lipid Research Clinic family study: cultural and biological determinants of lipids and lipoprotein concentrations.

    PubMed Central

    Rao, D C; Laskarzewski, P M; Morrison, J A; Khoury, P; Kelly, K; Wette, R; Russell, J; Glueck, C J

    1982-01-01

    A general linear model is described here for cultural and biological inheritance of lipids and lipoproteins. This model involves 10 parameters to be estimated from a total of 17 correlations, leaving ample degrees of freedom to test the goodness of fit. The model fits very well to each of the five lipid and lipoprotein variables analyzed here from a Lipid Research Clinic family data set. Both genetic and cultural inheritance are significant for each trait with the single exception that triglyceride levels fail to support genetic inheritance. Under the most parsimonious hypothesis, the genetic heritability (h2) ranges from .194 +/- .092 for triglyceride to .624 +/- .093 for low-density lipoprotein-cholesterol. Cultural heritability ranges from .070 +/- .030 for total cholesterol to .149 +/- .034 for triglyceride. PMID:7180846

  18. Structural organization of DMPC lipid layers on chemically micropatterned self-assembled monolayers as biomimetic systems.

    PubMed

    Brechling, A; Pohl, M; Kleineberg, U; Heinzmann, U

    2004-08-26

    The growth structure of DMPC lipid layers on hydrophobic and hydrophilic alkylsilane-based self-assembled monolayers adsorbed on silicon has been investigated by means of X-ray reflectometry and atomic force microscopy. Hydrophilic modification of hydrophobically terminated ODS-SAMs has been achieved by dose-controlled irradiation with DUV light. While island formation of small DMPC bilayer islands is observed on hydrophobic SAM surfaces, closed layers of DMPC monolayers are formed on hydrophilic SAM surfaces. Furthermore, DMPC adsorption on chemically micropatterned substrates with alternating hydrophobic/hydrophilic surface properties has been studied by imaging ellipsometry and photoemission microscopy. Indication for at least partial bridging of hydrophobic areas by an adsorbed DMPC monolayer has been found. PMID:15288947

  19. The lymph lipid precursor pool is a key determinant of intestinal lymphatic drug transport.

    PubMed

    Trevaskis, Natalie L; Porter, Christopher J H; Charman, William N

    2006-02-01

    The influence of the size and turnover kinetics of the enterocyte-based lymph lipid precursor pool (LLPP) on intestinal lymphatic drug transport has been examined. Mesenteric lymph duct-cannulated rats were infused intraduodenally with low (2-5 mg/h) or high (20 mg/h) lipid-dose formulations containing 100 microg/h halofantrine (Hf, a model drug) and 1 microCi/h (14)C-oleic acid (OA) (as a marker for lipid transport) until steady-state rates of lipid(dX(L)/dt)(ss) and drug (dD(L)/dt)(ss) transport in lymph were obtained. After 5 h, the infusion was changed to formulations of the same composition but excluding (14)C-OA and Hf, allowing calculation of the first order rate constants describing turnover of lipid (K(X)) and drug (K(D)) from the LLPP into the lymph from the washout kinetics. The mass of lipid (X(LP)) and drug (D(LP)) in the LLPP was also determined. Biliary-lipid output was determined in a separate group of rats that had been infused with the same formulations. The results indicate that after administration of high lipid doses, lymphatic drug transport is dependent on the mass of exogenous lipid available in the LLPP and the rate of lipid pool turnover into the lymph. In contrast, after administration of low lipid doses, biliary-derived endogenous lipids are most likely to be the primary drivers of drug incorporation into the LLPP and lymph. Therefore, the LLPP size and composition seem to be major determinants of lymphatic drug transport, and formulation components, which increase lipid pool size, may therefore enhance lymphatic drug transport. PMID:16249368

  20. Bacterial S-layer protein coupling to lipids: x-ray reflectivity and grazing incidence diffraction studies.

    PubMed

    Weygand, M; Wetzer, B; Pum, D; Sleytr, U B; Cuvillier, N; Kjaer, K; Howes, P B; Lösche, M

    1999-01-01

    The coupling of bacterial surface (S)-layer proteins to lipid membranes is studied in molecular detail for proteins from Bacillus sphaericus CCM2177 and B. coagulans E38-66 recrystallized at dipalmitoylphosphatidylethanolamine (DPPE) monolayers on aqueous buffer. A comparison of the monolayer structure before and after protein recrystallization shows minimal reorganization of the lipid chains. By contrast, the lipid headgroups show major rearrangements. For the B. sphaericus CCM2177 protein underneath DPPE monolayers, x-ray reflectivity data suggest that amino acid side chains intercalate the lipid headgroups at least to the phosphate moieties, and probably further beyond. The number of electrons in the headgroup region increases by more than four per lipid. Analysis of the changes of the deduced electron density profiles in terms of a molecular interpretation shows that the phosphatidylethanolamine headgroups must reorient toward the surface normal to accommodate such changes. In terms of the protein structure (which is as yet unknown in three dimensions), the electron density profile reveals a thickness lz approximately 90 A of the recrystallized S-layer and shows water-filled cavities near its center. The protein volume fraction reaches maxima of >60% in two horizontal sections of the S-layer, close to the lipid monolayer and close to the free subphase. In between it drops to approximately 20%. Four S-layer protein monomers are located within the unit cell of a square lattice with a spacing of approximately 131 A. PMID:9876158

  1. Layer-by-layer coated lipid-polymer hybrid nanoparticles designed for use in anticancer drug delivery.

    PubMed

    Ramasamy, Thiruganesh; Tran, Tuan Hiep; Choi, Ju Yeon; Cho, Hyuk Jun; Kim, Jeong Hwan; Yong, Chul Soon; Choi, Han-Gon; Kim, Jong Oh

    2014-02-15

    Polyelectrolyte multilayers created via sequential adsorption of complimentary materials may be useful in the delivery of small molecules such as anti-cancer drugs. In this study, layer-by-layer (LbL) nanoarchitectures were prepared by step-wise deposition of naturally derived chitosan and hyaluronic acid on negatively charged hybrid solid lipid nanoparticles (SLNs). A doxorubicin/dextran sulfate complex was incorporated into the SLNs. This resulted in the production of spherical nanoparticles ∼ 265 nm in diameter, with a zeta potential of approximately -12 mV. The nanoparticles were physically stable and exhibited controlled doxorubicin (DOX) release kinetics. Further pharmacokinetic manipulations revealed that in comparison with both free DOX and uncoated DOX-loaded SLNs, LbL-functionalized SLNs remarkably enhanced the circulation half-life and decreased the elimination rate of the drug. Cumulatively, our results suggest that this novel LbL-coated system, with a pH-responsive shell and molecularly targeted entities, has the potential to act as a vehicle to deliver medication to targeted tumor regions. PMID:24507332

  2. Glass transition temperature of water confined in lipid membranes as determined by anelastic spectroscopy

    NASA Astrophysics Data System (ADS)

    Castellano, C.; Generosi, J.; Congiu, A.; Cantelli, R.

    2006-12-01

    The research of gene delivery vehicles used in gene therapy is focused on nonviral vectors like lipid membranes. Such vectors, nonimmunogenic and biodegradable, are formed by complexation of DNA with a mixture of cationic lipids and a neutral colipid which improve the transfection efficiency. A main topic related to lipid membrane dynamics is their capability to spontaneously confine water. At present the value of the glass transition temperature (Tg) is largely debated and determined only by some indirect methods. Here the authors show that anelastic spectroscopy allows the confined water Tg value to be directly identified in several lipid mixtures.

  3. Determining Membrane Protein-Lipid Binding Thermodynamics Using Native Mass Spectrometry.

    PubMed

    Cong, Xiao; Liu, Yang; Liu, Wen; Liang, Xiaowen; Russell, David H; Laganowsky, Arthur

    2016-04-01

    Membrane proteins are embedded in the biological membrane where the chemically diverse lipid environment can modulate their structure and function. However, the thermodynamics governing the molecular recognition and interaction of lipids with membrane proteins is poorly understood. Here, we report a method using native mass spectrometry (MS), to determine thermodynamics of individual ligand binding events to proteins. Unlike conventional methods, native MS can resolve individual ligand binding events and, coupled with an apparatus to control the temperature, determine binding thermodynamic parameters, such as for protein-lipid interactions. We validated our approach using three soluble protein-ligand systems (maltose binding protein, lysozyme, and nitrogen regulatory protein) and obtained similar results to those using isothermal titration calorimetry and surface plasmon resonance. We also determined for the first time the thermodynamics of individual lipid binding to the ammonia channel (AmtB), an integral membrane protein from Escherichia coli. Remarkably, we observed distinct thermodynamic signatures for the binding of different lipids and entropy-enthalpy compensation for binding lipids of variable chain length. Additionally, using a mutant form of AmtB that abolishes a specific phosphatidylglycerol (PG) binding site, we observed distinct changes in the thermodynamic signatures for binding PG, implying these signatures can identify key residues involved in specific lipid binding and potentially differentiate between specific lipid binding sites. PMID:27015007

  4. Purification and lipid-layer crystallization of yeast RNA polymerase II.

    PubMed Central

    Edwards, A M; Darst, S A; Feaver, W J; Thompson, N E; Burgess, R R; Kornberg, R D

    1990-01-01

    Yeast RNA polymerase II was purified to homogeneity by a rapid procedure involving immunoaffinity chromatography. The purified enzyme contained 10 subunits, as reported for conventional preparations, but with no detectable proteolysis of the largest subunit. In assays of initiation of transcription at the yeast CYC1 promoter, the enzyme complemented the deficiency of an extract from a strain that produces a temperature-sensitive polymerase II. Mammalian RNA polymerase II was inactive in this initiation assay. The purified yeast enzyme formed two-dimensional crystals on positively charged lipid layers, as previously found for Escherichia coli RNA polymerase holoenzyme. Image analysis of electron micrographs of crystals in negative stain, which diffracted to about 30-A resolution, showed protein densities of dimensions consistent with those of single polymerase molecules. Images PMID:2179949

  5. Determination of partition coefficient of spin probe between different lipid membrane phases.

    PubMed

    Arsov, Zoran; Strancar, Janez

    2005-01-01

    Model lipid membranes made from binary mixtures of dimyristoylphosphatidylcholine/dipalmitoylphosphatidylcholine (DMPC/DPPC) and dimyristoylphosphatidylcholine/cholesterol (DMPC/Chol) exhibit coexistence of diverse lipid phases at appropriate temperature and composition. Since lipids in different phases show different structural and motional properties, it is expected that the corresponding spin probe electron paramagnetic resonance (EPR) spectra will be superposition of several spectral components. From comparison of proportions of spectral components of the EPR spectrum with the fractions of the corresponding lipid phases obtained from known phase diagrams the partition coefficient of spin probe methyl ester of 5-doxyl palmitate between different lipid phases was determined. The results indicate that the used spin probe partitions approximately equally between different phases. PMID:16309270

  6. The real reason for having a meibomian lipid layer covering the outer surface of the tear film - A review.

    PubMed

    Millar, Thomas J; Schuett, Burkhardt S

    2015-08-01

    This review critically evaluates a broad range of literature in order to show the relationship between meibum, tear lipids and the tear film lipid layer (TFLL). The relationship of meibum composition to dry eye syndrome is briefly discussed. The review also explores the interactions between aqueous and the TFLL by examining the correlations between meibomian lipids and lipids extracted from whole tears, and by considering protein adsorption to the TFLL from the aqueous. Although it is clear to the authors that a normal tear film resists evaporation, an emerging idea from the literature is that the main purpose of the TFLL is to allow the spread of the tear film and to prevent its collapse onto the ocular surface, rather than to be an evaporative blanket. Current models on the possible structure of the TFLL are also examined. PMID:25981748

  7. The design of naproxen solid lipid nanoparticles to target skin layers.

    PubMed

    Akbari, Jafar; Saeedi, Majid; Morteza-Semnani, Katayoun; Rostamkalaei, Seyyed Sohrab; Asadi, Masoumeh; Asare-Addo, Kofi; Nokhodchi, Ali

    2016-09-01

    The aim of the current investigation was to produce naproxen solid lipid nanoparticles (Nap-SLNs) by the ultrasonication method to improve its skin permeation and also to investigate the influence of Hydrophilic-lipophilic balance (HLB) changes on nanoparticles properties. The properties of obtained SLNs loaded with naproxen were characterized by photon correlation spectroscopy (PCS), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). FT-IR was also used to investigate any interaction between naproxen and the excipients used at the molecular level during the preparation of the SLNs. The performance of the formulations was investigated in terms of skin permeation and also the retention of the drug by the skin. It was found that generally, with increasing the lipid concentration, the average particle size and polydispersity index (PDI) of SLNs increased from 94.257±4.852nm to 143.90±2.685nm and from 0.293±0.037 to 0.525±0.038 respectively. The results also showed that a reduction in the HLB resulted in an increase in the PDI, particle size, zeta potential and entrapment efficiency (EE%). DSC showed that the naproxen encapsulated in the SLNs was in its amorphous form. The peaks of prominent functional groups of naproxen were found in the FT-IR spectra of naproxen-SLN, which confirmed the entrapment of naproxen in the lipid matrix. FT-IR results also ruled out any chemical interaction between drug and the chemicals used in the preparation of SLNs. The amount of naproxen detected in the receptor chamber at all the sampling times for the reference formulation (naproxen solution containing all surfactants at pH 7.4) was higher than that of the Nap-SLN8 formulation. Nap-SLN8 showed an increase in the concentration of naproxen in the skin layer with less systemic absorption. This indicates that most of the drug in Nap-SLN8 remains in the skin which can reduce the side effect of systemic absorption of the drug and increases the

  8. Chill-coma recovery time, age and sex determine lipid profiles in Ceratitis capitata tissues.

    PubMed

    Pujol-Lereis, Luciana Mercedes; Fagali, Natalia Soledad; Rabossi, Alejandro; Catalá, Ángel; Quesada-Allué, Luis Alberto

    2016-04-01

    The remodeling of membrane composition by changes in phospholipid head groups and fatty acids (FA) degree of unsaturation has been associated with the maintenance of membrane homeostasis under stress conditions. Overall lipid levels and the composition of cuticle lipids also influence insect stress resistance and tissue protection. In a previous study, we demonstrated differences in survival, behavior and Cu/Zn superoxide dismutase gene expression between subgroups of Ceratitis capitata flies that had a reversible recovery from chill-coma and those that developed chilling-injury. Here, we analyzed lipid profiles from comparable subgroups of 15 and 30-day-old flies separated according to their recovery time after a chill-coma treatment. Neutral and polar lipid classes of chill-coma subgroups were separated by thin layer chromatography and quantified by densitometry. FA composition of polar lipids of chill-coma subgroups and non-stressed flies was evaluated using gas chromatography coupled to mass spectrometry. Higher amounts of neutral lipids such as triglycerides, diacylglycerol, wax esters, sterol esters and free esters were found in male flies that recovered faster from chill-coma compared to slower flies. A multivariate analysis revealed changes in patterns of storage and cuticle lipids among subgroups both in males and females. FA unsaturation increased after cold exposure, and was higher in thorax of slower subgroups compared to faster subgroups. The changes in neutral lipid patterns and FA composition depended on recovery time, sex, age and body-part, and were not specifically associated with the development of chilling-injury. An analysis of phospholipid classes showed that the phosphatidylcholine to lysophosphatidylcholine ratio (PC/LPC) was significantly higher, or showed a tendency, in subgroups that may have developed chilling-injury compared to those with a reversible recovery from coma. PMID:26868723

  9. Fabrication of fracture-free nanoglassified substrates by layer-by-layer deposition with a paint gun technique for real-time monitoring of protein-lipid interactions.

    PubMed

    Linman, Matthew J; Culver, Sean P; Cheng, Quan

    2009-03-01

    New sensing materials that are robust, biocompatible, and amenable to array fabrication are vital to the development of novel bioassays. Herein we report the fabrication of ultrathin (ca. 5-8 nm) glass (silicate) layers on top of a gold surface for surface plasmon resonance (SPR) biosensing applications. The nanoglass layers are fabricated by layer-by-layer (LbL) deposition of poly(allylamine) hydrochloride (PAH) and sodium silicate (SiO(x)), followed by calcination at high temperature. To deposit these layers in a uniform and reproducible manner, we employed a high-volume, low-pressure (HVLP) paint gun technique that offers high precision and better control through pressurized nitrogen gas. The new substrates are stable in solution for a long period of time, and scanning electron microscopy (SEM) images confirm that these films are nearly fracture-free. In addition, atomic force microscopy (AFM) indicates that the surface roughness of the silicate layers is low (rms = 2 to 3 nm), similar to that of bare glass slides. By tuning the experimental parameters such as HVLP gun pressure and layers deposited, different surface morphology could be obtained as revealed by fluorescence microscopy and SEM images. To demonstrate the utility of these ultrathin, fracture-free substrates, lipid bilayer membranes composed of phosphorylated derivatives of phosphoinositides (PIs) were deposited on the new substrates for biosensing applications. Fluorescence recovery after photobleaching (FRAP) data indicated that these lipid components in the membranes were highly mobile. Furthermore, interactions of PtdIns(4,5)P2 and PtdIns(4)P lipids with their respective binding proteins were detected with high sensitivity by using SPR spectroscopy. This method of glass deposition can be combined with already well-developed surface chemistry for a range of planar glass assay applications, and the process is amenable to automation for mass production of nanometer thick silicate chips in a highly

  10. Preparation of Oriented, Fully Hydrated Lipid Samples for Structure Determination Using X-Ray Scattering

    PubMed Central

    Tristram-Nagle, Stephanie A.

    2009-01-01

    Summary This chapter describes a method of sample preparation called “the rock and roll method,” which is basically a solvent evaporation technique with controlled manual sample movement during evaporation of solvent from lipid/solvent mixtures that produces well-oriented thick stacks of about 2000 lipid bilayers. Many lipid types have been oriented using different solvent mixtures that balance solubilization of the lipid with uniform deposition of the lipid solution onto solid substrates. These well-oriented thick stacks are then ideal samples for collection of both X-ray diffraction data in the gel phase and X-ray diffuse scattering data in the fluid phase of lipids. The degree of orientation is determined using visual inspection, polarizing microscopy, and a mosaic spread X-ray experiment. Atomic force microscopy is used to compare samples prepared using the rock and roll method with those prepared by spin-coating, which produces well-oriented but less homogeneous lipid stacks. These samples can be fully hydrated through the vapor provided that the hydration chamber has excellent temperature and humidity control. PMID:17951727

  11. Preparation of oriented, fully hydrated lipid samples for structure determination using X-ray scattering.

    PubMed

    Tristram-Nagle, Stephanie A

    2007-01-01

    This chapter describes a method of sample preparation called "the rock and roll method," which is basically a solvent evaporation technique with controlled manual sample movement during evaporation of solvent from lipid/solvent mixtures that produces well-oriented thick stacks of about 2000 lipid bilayers. Many lipid types have been oriented using different solvent mixtures that balance solubilization of the lipid with uniform deposition of the lipid solution onto solid substrates. These well-oriented thick stacks are then ideal samples for collection of both X-ray diffraction data in the gel phase and X-ray diffuse scattering data in the fluid phase of lipids. The degree of orientation is determined using visual inspection, polarizing microscopy, and a mosaic spread X-ray experiment. Atomic force microscopy is used to compare samples prepared using the rock and roll method with those prepared by spin-coating, which produces well-oriented but less homogeneous lipid stacks. These samples can be fully hydrated through the vapor provided that the hydration chamber has excellent temperature and humidity control. PMID:17951727

  12. Lipids that determine detergent resistance of MDCK cell membrane fractions.

    PubMed

    Manni, Marco M; Cano, Ainara; Alonso, Cristina; Goñi, Félix M

    2015-10-01

    A comparative lipidomic study has been performed of whole Madin-Darby canine kidney epithelial cells and of the detergent-resistant membrane fraction (DRM) obtained after treating the cells with the non-ionic detergent Triton X-100. The DRM were isolated following a standard procedure that is extensively used in cell biology studies. Significant differences were found in the lipid composition of the whole cells and of DRM. The latter were enriched in all the analyzed sphingolipid classes: sphingomyelins, ceramides and hexosylceramides. Diacylglycerols were also preferentially found in DRM. The detergent-resistant fraction was also enriched in saturated over unsaturated fatty acyl chains, and in sn-1 acyl chains containing 16 carbon atoms, over the longer and shorter ones. The glycerophospholipid species phosphatidylethanolamines and phosphatidylinositols, that were mainly unsaturated, did not show a preference for DRM. Phosphatidylcholines were an intermediate case: the saturated, but not the unsaturated species were found preferentially in DRM. The question remains on whether these DRM, recovered from detergent-membrane mixtures by floatation over a sucrose gradient, really correspond to membrane domains existing in the cell membrane prior to detergent treatment. PMID:26320877

  13. Investigation of multimodal waveguides to determine parameters of covering layer

    NASA Astrophysics Data System (ADS)

    Auguściuk, Elżbieta; Zieliński, Jarosław

    2006-02-01

    Investigation of liquid thin layers deposited on multimodal waveguide with gradient - index profile has been presented. Properties of the layers have been studied by the generalized m-line spectroscopy method. Deposited on the planar waveguide thin liquid layers have been investigated on the range refractive index 1.0002 - 1.5300. The profile of refractive index of waveguide has not been deformed because of depositing of the thin layer. Depositing of the thin layer on multimodal planar waveguide has caused the change of coupling angle to the waveguide but proportionately to successive modes of the waveguide structure. This study will be helpful to determine, for instance, illness changes of diabetic patients (sugar level in blood).

  14. Determination of HEat Capacity of Yucca Mountain Strtigraphic Layers

    SciTech Connect

    T. Hadgu; C. Lum; J.E. Bean

    2006-06-20

    The heat generated from the radioactive waste to be placed in the proposed geologic repository at Yucca Mountain, Nevada, will affect the thermal-hydrology of the Yucca Mountain stratigraphic layers. In order to assess the effect of the movement of repository heat into the fractured rocks accurate determination of thermodynamic and hydraulic properties is important. Heat capacity is one of the properties that are required to evaluate energy storage in the fractured rock. Rock-grain heat capacity, the subject of this study, is the heat capacity of the solid part of the rock. Yucca Mountain consists of alternating lithostratigraphic units of welded and non-welded ash-flow tuff, mainly rhyolitic in composition and displaying varying degrees of vitrification and alteration. A number of methods exist that can be used to evaluate heat capacity of the stratigraphic layers that consist of different compositions. In this study, the mineral summation method has been used to quantify the heat capacity of the stratigraphic layers based on Kopp's rule. The mineral summation method is an addition of the weighted heat capacity of each mineral found in a specific layer. For this study the weighting was done based on the mass percentage of each mineral in the layer. The method utilized a mineralogic map of the rocks at the Yucca Mountain repository site. The Calico Hills formation and adjacent bedded tuff layers display a bimodal mineral distribution of vitric and zeolitic zones with differing mineralogies. Based on this bimodal distribution in zeolite abundance, the boundary between the vitric and zeolitic zones was selected to be 15% zeolitic abundance. Thus, based on the zeolite abundance, subdivisions have been introduced to these layers into ''vitric'' and ''zeolitic'' zones. Heat capacity values have been calculated for these layers both as ''layer average'' and ''zone average''. The heat capacity determination method presented in this report did not account for spatial

  15. Statistical Comparison of Classifiers Applied to the Interferential Tear Film Lipid Layer Automatic Classification

    PubMed Central

    Remeseiro, B.; Penas, M.; Mosquera, A.; Novo, J.; Penedo, M. G.; Yebra-Pimentel, E.

    2012-01-01

    The tear film lipid layer is heterogeneous among the population. Its classification depends on its thickness and can be done using the interference pattern categories proposed by Guillon. The interference phenomena can be characterised as a colour texture pattern, which can be automatically classified into one of these categories. From a photography of the eye, a region of interest is detected and its low-level features are extracted, generating a feature vector that describes it, to be finally classified in one of the target categories. This paper presents an exhaustive study about the problem at hand using different texture analysis methods in three colour spaces and different machine learning algorithms. All these methods and classifiers have been tested on a dataset composed of 105 images from healthy subjects and the results have been statistically analysed. As a result, the manual process done by experts can be automated with the benefits of being faster and unaffected by subjective factors, with maximum accuracy over 95%. PMID:22567040

  16. Improvement in the Iatroscan thin-layer chromatographic-flame ionisation detection analysis of marine lipids. Separation and quantitation of monoacylglycerols and diacylglycerols in standards and natural samples.

    PubMed

    Striby, L; Lafont, R; Goutx, M

    1999-07-23

    Mono- and diacylglycerols are important intermediates in glycerolipid biodegradation and intracellular signalling pathways. A method for mass determination of these lipid classes in marine particles was developed using the Iatroscan, which combines thin layer chromatography (TLC) and flame ionisation detection (FID) techniques. We improved existing protocols by adding two elution steps: hexane-diethyl-ether-formic acid (70:30:0.2, v/v/v) after triacylglycerol and free fatty acid scan, and acetone 100% followed by chloroform-acetone-formic acid (99:1:0.2, v/v/v) after 1,2 diacylglycerols. Diacylglycerol isomers 1,2 and 1,3 were separated from each other, as well as from free sterols in standards and marine lipids from sediment trap particles. Monoacylglycerols were separated from pigments and galactosyl-lipids in the same trap samples and in a rich pigment phytoplankton extract of Dunaliella viridis. Quantitation of each class in samples was performed after calibration with 0.5 to 2 micrograms of standards. As many as 17 lipid classes can be identified and quantified in samples using this proposed six-step development. PMID:10457435

  17. Direct comparison of fatty acid ratios in single cellular lipid droplets as determined by Raman spectroscopy and gas chromatography

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cellular lipid droplets are the least studied and least understood cellular organelles in eukaryotic and prokaryotic cells. Despite a broad research trying to understand lipid droplets it has not been possible to determine the composition of individual cellular lipid droplets. In this paper we prese...

  18. Carbon and nitrogen abundances determined from transition layer lines

    NASA Technical Reports Server (NTRS)

    Boehm-Vitense, Erika; Mena-Werth, Jose

    1992-01-01

    The possibility of determining relative carbon, nitrogen, and silicon abundances from the emission-line fluxes in the lower transition layers between stellar chromospheres and coronae is explored. Observations for main-sequence and luminosity class IV stars with presumably solar element abundances show that for the lower transition layers Em = BT sup -gamma. For a given carbon abundance the constants gamma and B in this relation can be determined from the C II and C IV emission-line fluxes. From the N V and S IV lines, the abundances of these elements relative to carbon can be determined from their surface emission-line fluxes. Ratios of N/C abundances determined in this way for some giants and supergiants agree within the limits of errors with those determined from molecular bands. For giants, an increase in the ratio of N/C at B-V of about 0.8 is found, as expected theoretically.

  19. [Spectrofluorometric ultramicroassay for determining the plasma lipid peroxidation index by the thiobarbituric acid test].

    PubMed

    Pré, J

    1991-01-01

    A simple, inexpensive spectrofluorometric ultramicroassay for determining the plasma lipid peroxidation index is described. Plasma is incubated for 60 minutes at 95 degrees C in a thiobarbituric acetate buffer medium (pH 3,5) with butylhydroxytoluene and Fe . The chromogen is then extracted in butanol 1-pyridine and quantified by spectrofluorometry (exc.: 532 nm; em: 553 nm). The mean value of the plasma thiobarbituric lipid peroxidation index determined by this method in 101 healthy non-smokers (age 39.1 +/- 8.7 years) was found to be 1.61 +/- 0.72. PMID:2011414

  20. Beneath the minerals, a layer of round lipid particles was identified to mediate collagen calcification in compact bone formation.

    PubMed

    Xu, Shaohua; Yu, Jianqing J

    2006-12-01

    Astronauts lose 1-2% of their bone minerals per month during space flights. A systematic search for a countermeasure relies on a good understanding of the mechanism of bone formation at the molecular level. How collagen fibers, the dominant matrix protein in bones, are mineralized remains mysterious. Atomic force microscopy was carried out, in combination with immunostaining and Western blotting, on bovine tibia to identify unrecognized building blocks involved in bone formation and for an elucidation of the process of collagen calcification in bone formation. Before demineralization, tiles of hydroxyapatite crystals were found stacked along bundles of collagen fibers. These tiles were homogeneous in size and shape with dimensions 0.69 x 0.77 x 0.2 micro m(3). Demineralization dissolved these tiles and revealed small spheres with an apparent diameter around 145 nm. These spheres appeared to be lipid particles since organic solvents dissolved them. The parallel collagen bundles had widths mostly <2 micro m. Composition analysis of compact bones indicated a high content of apolar lipids, including triglycerides and cholesterol esters. Apolar lipids are known to form lipid droplets or lipoproteins, and these spheres are unlikely to be matrix vesicles as reported for collagen calcification in epiphyseal cartilages. Results from this study suggest that the layer of round lipid particles on collagen fibers mediates the mineral deposition onto the fibers. The homogeneous size of these lipid particles and the presence of apolipoprotein in demineralized bone tissue suggest the possibility that these particles might be of lipoprotein origin. More studies are needed to verify the last claim and to exclude the possibility that they are secreted lipid droplets. PMID:16980361

  1. One-step encapsulation of siRNA between lipid-layers of multi-layer polycation liposomes by lipoplex freeze-thawing.

    PubMed

    Koide, Hiroyuki; Okamoto, Ayaka; Tsuchida, Hiroki; Ando, Hidenori; Ariizumi, Saki; Kiyokawa, Chiaki; Hashimoto, Masahiro; Asai, Tomohiro; Dewa, Takehisa; Oku, Naoto

    2016-04-28

    Small interfering RNA (siRNA) has the potential to be a candidate as a cure for intractable diseases. However, an appropriate vector is required for siRNA delivery because of the low transfection efficiency of siRNA without a vector and its easy degradation in vivo. Here, we report a simple, only one step, and efficient method for siRNA encapsulation into a lipidic nanocarrier by freeze-thawing: siRNA was entrapped between the lipid layers of multi-layer liposomes by freeze-thawing of lipoplexes composed of polycation liposomes (PCLs) and siRNA. siRNA-holding capacity to the PCL was increased by repeating freeze-thaw of the lipoplex up to 5cycles. Although siRNA in the conventional lipoplex was degraded after incubation in 90% fetal bovine serum for 72h, siRNA in the frozen and thawed lipoplex was not degraded. Interestingly, we found that the lipoplex formed a "packed multi-layer" structure after the freeze-thawing of "single-layer" PCL and siRNA complex, suggesting that siRNA exists between the lipid layers working as a binder. The frozen and thawed lipoplex showed significantly higher knockdown efficacy compared with the conventional lipoplex. In addition, PEGylated freeze-thawed lipoplexes delivered a higher amount of siRNA to a tumor in vivo compared with the PEGylated conventional ones. These results provide an attractive strategy for "one-step" encapsulation of siRNA into liposomes by freeze-thawing. PMID:26826309

  2. Promoting the selection and maintenance of fetal liver stem/progenitor cell colonies by layer-by-layer polypeptide tethered supported lipid bilayer.

    PubMed

    Lee, I-Chi; Liu, Yung-Chiang; Tsai, Hsuan-Ang; Shen, Chia-Ning; Chang, Ying-Chih

    2014-12-10

    In this study, we designed and constructed a series of layer-by-layer polypeptide adsorbed supported lipid bilayer (SLB) films as a novel and label-free platform for the isolation and maintenance of rare populated stem cells. In particular, four alternative layers of anionic poly-l-glutamic acid and cationic poly-l-lysine were sequentially deposited on an anionic SLB. We found that the fetal liver stem/progenitor cells from the primary culture were selected and formed colonies on all layer-by-layer polypeptide adsorbed SLB surfaces, regardless of the number of alternative layers and the net charges on those layers. Interestingly, these isolated stem/progenitor cells formed colonies which were maintained for an 8 day observation period. Quartz crystal microbalance with dissipation measurements showed that all SLB-polypeptide films were protein resistant with serum levels significantly lower than those on the polypeptide multilayer films without an underlying SLB. We suggest the fluidic SLB promotes selective binding while minimizing the cell-surface interaction due to its nonfouling nature, thus limiting stem cell colonies from spreading. PMID:25243588

  3. Determining Structural and Mechanical Properties from Molecular Dynamics Simulations of Lipid Vesicles

    PubMed Central

    2015-01-01

    We have developed an algorithm to determine membrane structure, area per lipid, and bending rigidity from molecular dynamics simulations of lipid vesicles. Current methods to extract structure from vesicle simulations define densities relative to the global center of mass of the vesicle. This approach ignores the long-wavelength fluctuations (undulations) that develop across the sphere and broaden the underlying structure. Our method establishes a local reference frame by defining a radially undulating reference surface (URS) and thereby removes the broadening effect of the undulations. Using an arc-length low-pass filter, we render the URS by defining the bilayer midplane on an equi-angular θ, ϕ-grid (colatitude, longitude). This surface is then expanded onto a truncated series of spherical harmonics. The spherical harmonic coefficients characterize the long-wavelength fluctuations that define both the local reference frame—used to determine the bilayer’s structure—and the area per lipid (AL) along the undulating surface. Additionally, the resulting power spectrum of spherical harmonic coefficients can be fit to a Helfrich continuum model for membrane bending in spherical geometry to extract bending rigidity (kc). kc values determined for both DMPC and DMPC + cholesterol (30 mol %) vesicles are consistent with values from corresponding flat-patch systems determined using an independent, previously published spectral method. These new tools to accurately extract structure, AL, and kc should prove invaluable in evaluating the construction and equilibration of lipid vesicle simulations. PMID:25221448

  4. Determining Structural and Mechanical Properties from Molecular Dynamics Simulations of Lipid Vesicles.

    PubMed

    Braun, Anthony R; Sachs, Jonathan N

    2014-09-01

    We have developed an algorithm to determine membrane structure, area per lipid, and bending rigidity from molecular dynamics simulations of lipid vesicles. Current methods to extract structure from vesicle simulations define densities relative to the global center of mass of the vesicle. This approach ignores the long-wavelength fluctuations (undulations) that develop across the sphere and broaden the underlying structure. Our method establishes a local reference frame by defining a radially undulating reference surface (URS) and thereby removes the broadening effect of the undulations. Using an arc-length low-pass filter, we render the URS by defining the bilayer midplane on an equi-angular θ, ϕ-grid (colatitude, longitude). This surface is then expanded onto a truncated series of spherical harmonics. The spherical harmonic coefficients characterize the long-wavelength fluctuations that define both the local reference frame-used to determine the bilayer's structure-and the area per lipid (A L) along the undulating surface. Additionally, the resulting power spectrum of spherical harmonic coefficients can be fit to a Helfrich continuum model for membrane bending in spherical geometry to extract bending rigidity (k c). k c values determined for both DMPC and DMPC + cholesterol (30 mol %) vesicles are consistent with values from corresponding flat-patch systems determined using an independent, previously published spectral method. These new tools to accurately extract structure, A L, and k c should prove invaluable in evaluating the construction and equilibration of lipid vesicle simulations. PMID:25221448

  5. Experimental Determination of High-Order Bending Elastic Constants of Lipid Bilayers.

    PubMed

    Toscano-Flores, Liliana G; Jacinto-Méndez, Damián; Carbajal-Tinoco, Mauricio D

    2016-06-30

    We present a method to describe the formation of small lipid vesicles in terms of three bending elastic constants that can be experimentally measured. Our method combines a general expression of the elastic free energy of the bilayer and the thermodynamic description of molecular aggregation. The resulting model requires the size distribution of liposomes, which is determined from the X-ray scattered intensity spectra of vesicular dispersions. By using two different preparation methods, we studied a series of vesicular solutions made of distinct lipids and we obtained their corresponding bending elastic constants that are consistent with known bending rigidities. PMID:27267752

  6. Milk Fat Content and DGAT1 Genotype Determine Lipid Composition of the Milk Fat Globule Membrane

    PubMed Central

    Argov-Argaman, Nurit; Mida, Kfir; Cohen, Bat-Chen; Visker, Marleen; Hettinga, Kasper

    2013-01-01

    During secretion of milk fat globules, triacylglycerol (TAG) droplets are enveloped by a phospholipid (PL) trilayer. Globule size has been found to be related to polar lipid composition and fat content, and milk fat content and fatty acid composition have been associated with the diacylglycerol acyltransferase 1 (DGAT1) K232A polymorphism; however, the association between the DGAT1 polymorphism and fat globule size and polar lipid composition has not been studied. The ratio between polar and neutral lipids as well as the composition of the polar lipids in milk has industrial as well as nutritional and health implications. Understanding phenotypic and genotypic factors influencing these parameters could contribute to improving milk lipid composition for dairy products. The focus of the present study was to determine the effect of both fat content and DGAT1 polymorphism on PL/TAG ratio, as a marker for milk fat globule size, and detailed PL composition. Milk samples were selected from 200 cows such that there were equal numbers of samples for the different fat contents as well as per DGAT1 genotype. Samples were analyzed for neutral and polar lipid concentration and composition. PL/TAG ratio was significantly associated with both fat content and DGAT1 genotype. Phosphatidylinositol and phosphatidylserine concentrations were associated with fat content*DGAT1 genotype with a stronger association for the AA than the KK genotype. Sphingomyelin concentration tended to interact with fat content*DGAT1 genotype. Phosphatidylethanolamine (PE) concentration showed a biphasic response to fat content, suggesting that multiple biological processes influence its concentration. These results provide a new direction for controlling polar lipid concentration and composition in milk through selective breeding of cows. PMID:23874734

  7. Determination of graphene layer thickness using optical image processing

    NASA Astrophysics Data System (ADS)

    Cook, Monica; Mani, R. G.

    2015-03-01

    Graphene, a single atomic layer of carbon arranged in a hexagonal lattice structure, is a valuable material in a wide range of research. A significant impediment to graphene research is the need to manually characterize the thickness of high-quality graphene produced via mechanical exfoliation. Traditional methods of characterizing the layer thickness of graphene, including Raman spectroscopy and atomic force microscopy, require expensive equipment and can be damaging to the graphene sample. We examine here a known alternative method for quantitatively determining the layer thickness of graphene on SiO2/Si based on optical image processing, which is quick, inexpensive, and non-invasive. Using RGB images of a candidate graphene sample and a background image, taken with a simple optical microscope and charge-coupled device (CCD) camera, we process the images with an algorithm based on Fresnel's law to obtain the contrast spectrum. Each layer of graphene exhibits a unique contrast spectrum for its particular substrate, which is measured and used for accurate layer identification. We also discuss how this algorithm can be generalized to characterize the thickness of other promising two-dimensional materials as well as more complex structures on a variety of substrates.

  8. Fabrication of massive sheets of single layer patterned arrays using lipid directed reengineered phi29 motor dodecamer.

    PubMed

    Xiao, Feng; Sun, Jinchuan; Coban, Oana; Schoen, Peter; Wang, Joseph Che-Yen; Cheng, R Holland; Guo, Peixuan

    2009-01-27

    The bottom-up assembly of patterned arrays is an exciting and important area in current nanotechnology. Arrays can be engineered to serve as components in chips for a virtually inexhaustible list of applications ranging from disease diagnosis to ultra-high-density data storage. Phi29 motor dodecamer has been reported to form elegant multilayer tetragonal arrays. However, multilayer protein arrays are of limited use for nanotechnological applications which demand nanoreplica or coating technologies. The ability to produce a single layer array of biological structures with high replication fidelity represents a significant advance in the area of nanomimetics. In this paper, we report on the assembly of single layer sheets of reengineered phi29 motor dodecamer. A thin lipid monolayer was used to direct the assembly of massive sheets of single layer patterned arrays of the reengineered motor dodecamer. Uniform, clean and highly ordered arrays were constructed as shown by both transmission electron microscopy and atomic force microscopy imaging. PMID:19206255

  9. Ordered stacking of F-actin layers and mixed lipid bilayers: a columnar liquid crystal.

    PubMed

    Caillé, A; Artzner, F; Amblard, F

    2013-01-25

    In this Letter, we show how the grooved helical structure of actin microfilaments (F-actin) interacting with mixed fluid lipid bilayers leads to handedness-independent 1D lipid bilayer undulations coupled to longitudinal in-plane ordering of the microfilaments. This longitudinal ordering is forced by the emerging in-plane compression and curvature energy terms of the straight 1D bilayer undulation wave fronts. Thereby, adjacent helices are set into registry along their long axis in their monolayer and π shifted between adjacent monolayers. An ordered composite multilamellar structure emerges by alternate stacking of these lipid bilayers and monolayers of F-actin. This two-dimensionally ordered system has the symmetries of a centered rectangular columnar liquid crystal, the straight 1D wave fronts playing the role of the classical molecular columns. PMID:25166203

  10. Simultaneous measurement of lipid and aqueous layers of tear film using optical coherence tomography and statistical decision theory

    NASA Astrophysics Data System (ADS)

    Huang, Jinxin; Clarkson, Eric; Kupinski, Matthew; Rolland, Jannick P.

    2014-03-01

    The prevalence of Dry Eye Disease (DED) in the USA is approximately 40 million in aging adults with about $3.8 billion economic burden. However, a comprehensive understanding of tear film dynamics, which is the prerequisite to advance the management of DED, is yet to be realized. To extend our understanding of tear film dynamics, we investigate the simultaneous estimation of the lipid and aqueous layers thicknesses with the combination of optical coherence tomography (OCT) and statistical decision theory. In specific, we develop a mathematical model for Fourier-domain OCT where we take into account the different statistical processes associated with the imaging chain. We formulate the first-order and second-order statistical quantities of the output of the OCT system, which can generate some simulated OCT spectra. A tear film model, which includes a lipid and aqueous layer on top of a rough corneal surface, is the object being imaged. Then we further implement a Maximum-likelihood (ML) estimator to interpret the simulated OCT data to estimate the thicknesses of both layers of the tear film. Results show that an axial resolution of 1 μm allows estimates down to nanometers scale. We use the root mean square error of the estimates as a metric to evaluate the system parameters, such as the tradeoff between the imaging speed and the precision of estimation. This framework further provides the theoretical basics to optimize the imaging setup for a specific thickness estimation task.

  11. Improved pharmacokinetics and enhanced tumor growth inhibition using a nanostructured lipid carrier loaded with doxorubicin and modified with a layer-by-layer polyelectrolyte coating.

    PubMed

    Mussi, Samuel V; Parekh, Gaurav; Pattekari, Pravin; Levchenko, Tatyana; Lvov, Yuri; Ferreira, Lucas A M; Torchilin, Vladimir P

    2015-11-10

    A nanostructured lipid carrier (NLC) loaded with doxorubicin (DOX) has been shown to be cytotoxic against the human cancer cell lines A549 and MCF-7/Adr. In attempts to improve formulation characteristics, enhance pharmacokinetics and antitumor effects, we modified the surface of these NLC with an alternating layer-by-layer (LbL) assembly of polycation and polyanion polyelectrolytes and an additional coating with PEG using a simple method of core shell attachment. The formulation had a narrow size distribution, longer residence in the blood, lower accumulation in the liver, higher accumulation in tumors and a significant tumor growth inhibition effect. Thus, NLC-DOX nanopreparations complexes modified by LbL coating have the potential to enhance the anticancer effects of DOX against tumors. PMID:26325314

  12. Nile red fluorescence screening facilitating neutral lipid phenotype determination in budding yeast, Saccharomyces cerevisiae, and the fission yeast Schizosaccharomyces pombe.

    PubMed

    Rostron, Kerry A; Rolph, Carole E; Lawrence, Clare L

    2015-07-01

    Investigation of yeast neutral lipid accumulation is important for biotechnology and also for modelling aberrant lipid metabolism in human disease. The Nile red (NR) method has been extensively utilised to determine lipid phenotypes of yeast cells via microscopic means. NR assays have been used to differentiate lipid accumulation and relative amounts of lipid in oleaginous species but have not been thoroughly validated for phenotype determination arising from genetic modification. A modified NR assay, first described by Sitepu et al. (J Microbiol Methods 91:321-328, 2012), was able to detect neutral lipid changes in Saccharomyces cerevisiae deletion mutants with sensitivity similar to more advanced methodology. We have also be able to, for the first time, successfully apply the NR assay to the well characterised fission yeast Schizosaccharomyces pombe, an increasingly important organism in biotechnology. The described NR fluorescence assay is suitable for increased throughput and rapid screening of genetically modified strains in both the biotechnology industry and for modelling ectopic lipid production for a variety of human diseases. This ultimately negates the need for labour intensive and time consuming lipid analyses of samples that may not yield a desirable lipid phenotype, whilst genetic modifications impacting significantly on the cellular lipid phenotype can be further promoted for more in depth analyses. PMID:25948336

  13. Change in Tear Film Lipid Layer Thickness, Corneal Thickness, Volume and Topography after Superficial Cauterization for Conjunctivochalasis

    PubMed Central

    Chan, Tommy C. Y.; Ye, Cong; Ng, Paul KF; Li, Emmy Y. M.; Yuen, Hunter K. L.; Jhanji, Vishal

    2015-01-01

    We evaluated the change in tear film lipid layer thickness, corneal thickness, volume and topography after superficial cauterization of symptomatic conjunctivochalasis. Bilateral superficial conjunctival cauterization was performed in 36 eyes of 18 patients with symptomatic conjunctivochalasis. The mean age of patients (12 males, 6 females) was 68.6 ± 10.9 years (range: 44–83 years). Preoperatively, 28 eyes (77.8%) had grade 1 conjunctivochalasis, and 8 eyes (22.2%) had grade 2 conjunctivochalasis. At 1 month postoperatively, the severity of conjunctivochalasis decreased significantly (p < 0.001) and 29 eyes (80.6%) had grade 0 conjunctivochalasis whereas 7 eyes (19.4%) had grade 1 conjunctivochalasis. The mean Ocular Surface Disease Index score decreased from 31.5 ± 15.2 preoperatively to 21.5 ± 14.2 at the end of 1 month postoperatively (p = 0.001). There was a statistically significant increase in mean tear film lipid layer thickness 1 month after the surgery (49.6 ± 16.1 nm vs 62.6 ± 21.6 nm; p < 0.001). The central corneal thickness, thinnest corneal thickness and corneal volume decreased significantly postoperatively (p < 0.001). Our study showed that superficial conjunctival cauterization is an effective technique for management of conjunctivochalasis in the short term. An increase in tear film lipid layer thickness along with a decrease in corneal thickness and volume were observed after surgical correction of conjunctivochalasis. PMID:26184418

  14. Determination of lipid content of oleaginous microalgal biomass by NMR spectroscopic and GC-MS techniques.

    PubMed

    Sarpal, Amarijt S; Teixeira, Claudia M L L; Silva, Paulo R M; Lima, Gustavo M; Silva, Samantha R; Monteiro, Thays V; Cunha, Valnei S; Daroda, Romeu J

    2015-05-01

    Direct methods based on (1)H NMR spectroscopic techniques have been developed for the determination of neutral lipids (triglycerides and free fatty acids) and polar lipids (glyceroglycolipids/phospholipids) in the solvent extracts of oleaginous microalgal biomasses cultivated on a laboratory scale with two species in different media. The chemical shift assignments observed in the (1)H and (13)C NMR spectra corresponding to unsaturated (C18:N, N = 1-3, C20:3, C20:5, C22:6, epoxy) and saturated (C14-C18) fatty acid ester components in a complex matrix involving overlapped resonances have been unambiguously confirmed by the application of 2D NMR spectroscopy (total correlation spectroscopy and heteronuclear single quantum coherence-total correlation spectroscopy). The study of the effect of a polar lipid matrix on the determination of neutral lipids by an internal reference blending process by a systematic designed experimental protocol has provided absolute quantification. The fatty acid composition of algal extracts was found to be similar to that of vegetable oils containing saturated (C16-C18:0) and unsaturated (C18:N, N = 1-3, C20:N, N = 3-4, C22:6) fatty acids as confirmed by NMR spectroscopy and gas chromatography-mass spectrometry analyses. The NMR methods developed offer great potential for rapid screening of algal strains for generation of algal biomass with the desired lipid content, quality, and potential for biodiesel and value-added polyunsaturated fatty acids in view of the cost economics of the overall cost of generation of the biomass. PMID:25801382

  15. Application of Small-Angle Neutron and X-ray Scattering in Determining Lipid Bilayer Structure

    NASA Astrophysics Data System (ADS)

    Pan, Jianjun; Heberle, Frederick A.; Kucerka, Norbert; Tristram-Nagle, Stephanie; Szymanski, Michelle; Koepfinger, Mary; Katsaras, John

    2012-02-01

    Accurately determining lipid structure in biologically relevant fluid bilayers is not straightforward. We have recently developed a hybrid experimental/computational technique (i.e., the scattering density profile, or SDP model), which exploits the fact that neutron and X-ray scattering are sensitive to different bilayer thicknesses - the large difference in neutron scattering length density (SLD) between proteated lipid and deuterated water defines the overall bilayer thickness, while X-ray scattering resolves the headgroup-headgroup distance due to the large scattering contrast between the electron-rich phosphate groups and the hydrocarbon/aqueous medium. A key step in the SDP analysis is the use of MD simulations to parse the lipid molecule into fragments whose volume probability distributions follow simple analytical functional forms. Given the appropriate atomic scattering lengths, these volume probabilities can simultaneously predict both the neutron and X-ray SLD profiles, and hence the scattering form factors. Structural results for commonly used phosphatidylcholine and phosphatidylglycerol lipids will be given.

  16. Determination of PCBs and total lipids in edible fish and crab tissue using supercritical fluid extraction

    SciTech Connect

    Gavlor, M.; Hale, R.; Smith, C.; Thames, J.; Mothershead, R.

    1995-12-31

    An offline supercritical fluid extraction (SFE) method has been developed to determine PCB congeners and total tissue lipid content in edible fish and crab tissues collected from several river systems in Virginia. The method is rapid and safe, requiring only 40 minutes per sample and uses nonorganic solvents for total lipid extraction and only 1.5 mL isooctane for PCB extraction. The SFE approach compares favorably with soxhlet extraction, ASE and column elution. Over 800 fish and crab tissue samples were analyzed successfully, thus demonstrating the robustness of the method. Total lipid values obtained using SFE showed considerable spatial and interspecies variability ranging from 1.8% in blue crab (Callinectes sapidus) to 36.4% in striped bass (Morone saxatilis). Total PCB concentrations also varied greatly by site and species. These ranged from below the quantitation limit (1.0 {micro}1 g/kg) to 9,910 {micro}g/kg on a dry weight basis using GCELCD. Dominant PCB congeners detected were in good agreement with those reported by other researchers. Mean total PCB concentrations did not correlate well with total tissue lipid content.

  17. The first stages of lipid layer formation. A metastable impact electron spectroscopy study of egg lecithin dissolved in hydroxypropionitrile

    NASA Astrophysics Data System (ADS)

    Morgner, H.; Oberbrodhage, J.; Richter, K.

    By means of metastable impact electron spectroscopy we have studied the surface of a solution of egg lecithin in hydroxypropionitrile (HPN). The concentration has been varied between ˜5 × 10-4 moll-1 and ˜5 × 10-3 moll-1 which is far above the estimated critical micelle concentration. The age of the investigated surface has been adjusted between 2 ms and 18 ms. Within this range of parameters we have achieved full coverage of the surface by lecithin molecules. This situation is characterized by lecithin molecules lying flat on the HPN surface with an occupied area of σLec ≥ 190 Å2. This value is much larger than found for condensed layers with the hydrophobic tails pointing away from the surface. Thus, we conceive our experiment as the observation of the first steps of spontaneous lipid layer formation.

  18. The effect of supplementing layer diets with shark cartilage or chitosan on egg components and yolk lipids.

    PubMed

    Nogueira, C M; Zapata, J F F; Fuentes, M F F; Freitas, E R; Craveiro, A A; Aguiar, C M

    2003-05-01

    1. An experiment was designed to evaluate the effects of the addition of shark cartilage (SC) or chitosan (CH) to layer diets on egg component weights, yolk lipids and hen plasma lipids. 2. Hy-Line laying hens (80) were used during a 56 d feeding trial. Treatments were: basal diet (BD), BD + 20 g/kg SC, BD + 30 g/kg SC, BD + 20 g/kg CH and BD + 30 g/kg CH. Eggs were analysed on d 14, 28, 42 and 56. 3. Egg weight and egg component weights were not affected by these treatments throughout the experimental period. 4. After 14d of experimental feeding, cholesterol levels were higher in eggs from birds given BD + 20 g/kg CH and BD + 30 g/kg CH than in those from birds given BD. 5. Furthermore, eggs from hens given BD + 20 g/kg SC or BD + 20 g/kg CH were higher in palmitic and stearic acids and lower in oleic acid than those from birds fed on BD. After 56 d feeding, however, palmitic and stearic acid contents in eggs from hens given any of the supplemented diets were lower than in those from hens given BD, and oleic acid in eggs from hens given BD + 20 g/kg SC, BD + 30 g/kg SC and BD + 30 g/kg CH was higher than in those from birds fed on BD. 6. Plasma cholesterol and triacylglycerol levels were not significantly affected by dietary treatment. 7. Shark cartilage or chitosan at up to 30 g/kg in layer diets did not affect egg component weights (yolk, white and shell) and total lipid contents. During the period from 42 to 56d of experimental feeding, diets containing up to 30 g/kg chitosan reduced egg yolk contents of cholesterol, palmitic and stearic acids and increased the content of oleic acid. PMID:12828207

  19. Air motion determination by tracking humidity patterns in isentropic layers

    NASA Technical Reports Server (NTRS)

    Mancuso, R. L.; Hall, D. J.

    1975-01-01

    Determining air motions by tracking humidity patterns in isentropic layers was investigated. Upper-air rawinsonde data from the NSSL network and from the AVE-II pilot experiment were used to simulate temperature and humidity profile data that will eventually be available from geosynchronous satellites. Polynomial surfaces that move with time were fitted to the mixing-ratio values of the different isentropic layers. The velocity components of the polynomial surfaces are part of the coefficients that are determined in order to give an optimum fitting of the data. In the mid-troposphere, the derived humidity motions were in good agreement with the winds measured by rawinsondes so long as there were few or no clouds and the lapse rate was relatively stable. In the lower troposphere, the humidity motions were unreliable primarily because of nonadiabatic processes and unstable lapse rates. In the upper troposphere, the humidity amounts were too low to be measured with sufficient accuracy to give reliable results. However, it appears that humidity motions could be used to provide mid-tropospheric wind data over large regions of the globe.

  20. Interplay of electrostatics and lipid packing determines the binding of charged polymer coated nanoparticles to model membranes.

    PubMed

    Biswas, Nupur; Bhattacharya, Rupak; Saha, Arindam; Jana, Nikhil R; Basu, Jaydeep K

    2015-10-01

    Understanding of nanoparticle-membrane interactions is useful for various applications of nanoparticles like drug delivery and imaging. Here we report on the studies of interaction between hydrophilic charged polymer coated semiconductor quantum dot nanoparticles with model lipid membranes. Atomic force microscopy and X-ray reflectivity measurements suggest that cationic nanoparticles bind and penetrate bilayers of zwitterionic lipids. Penetration and binding depend on the extent of lipid packing and result in the disruption of the lipid bilayer accompanied by enhanced lipid diffusion. On the other hand, anionic nanoparticles show minimal membrane binding although, curiously, their interaction leads to reduction in lipid diffusivity. It is suggested that the enhanced binding of cationic QDs at higher lipid packing can be understood in terms of the effective surface potential of the bilayers which is tunable through membrane lipid packing. Our results bring forth the subtle interplay of membrane lipid packing and electrostatics which determine nanoparticle binding and penetration of model membranes with further implications for real cell membranes. PMID:26327393

  1. Methods for determining the height of the atmospheric boundary layer

    SciTech Connect

    Sugiyama, Gayle; Nasstrom, John S.

    1999-02-01

    The Atmospheric Release Advisory Capability (ARAC) is an operational emergency response program which provides real-time dose assessments of airborne pollutant releases. This report reviews methodologies for determining the height of the atmospheric boundary layer (ABL), which were investigated for use in the next generation of ARAC diagnostic and dispersion models. The ABL height, hABL, is an essential parameter in atmospheric dispersion modeling, controlling the extent of the vertical mixing of pollutants near the surface. Although eventually instrumentation (radiosonde, lidar, sodar, etc.) may provide accurate means for determining hABL, at present the availability of such data is too limited to provide a general capability for ARAC. The current operational ARAC diagnostic models use a fixed value of hABL for any given time. ARAC's new models support a horizontally-varying atmospheric boundary layer height, which is used to generate meteorological (mean wind, temperature, etc.) and turbulence fields. The purpose of the present work is to develop methods to derive the ABL height for all atmospheric stability regimes. One of our key requirements is to provide approaches which are applicable to routinely available data, which may be of limited temporal and spatial resolution. The final objective is to generate a consistent set of meteorological and turbulence or eddy diffusivity fields to drive the new ARAC dispersion model. A number of alternative definitions of the atmospheric boundary layer exist, leading to different approaches to deriving hABL. The definitions are based on either the turbulence characteristics of the atmosphere or the vertical structure of one or more meteorological variables. Most diagnostic analyses determine hABL from profiles of temperature or occasionally wind. A class of methods of considerable current interest are based on Richardson number criteria. Prognostic methods calculate the

  2. The Transmembrane Helix Tilt May Be Determined by the Balance between Precession Entropy and Lipid Perturbation

    PubMed Central

    2012-01-01

    Hydrophobic helical peptides interact with lipid bilayers in various modes, determined by the match between the length of the helix’s hydrophobic core and the thickness of the hydrocarbon region of the bilayer. For example, long helices may tilt with respect to the membrane normal to bury their hydrophobic cores in the membrane, and the lipid bilayer may stretch to match the helix length. Recent molecular dynamics simulations and potential of mean force calculations have shown that some TM helices whose lengths are equal to, or even shorter than, the bilayer thickness may also tilt. The tilt is driven by a gain in the helix precession entropy, which compensates for the free energy penalty resulting from membrane deformation. Using this free energy balance, we derived theoretically an equation of state, describing the dependence of the tilt on the helix length and membrane thickness. To this end, we conducted coarse-grained Monte Carlo simulations of the interaction of helices of various lengths with lipid bilayers of various thicknesses, reproducing and expanding the previous molecular dynamics simulations. Insight from the simulations facilitated the derivation of the theoretical model. The tilt angles calculated using the theoretical model agree well with our simulations and with previous calculations and measurements. PMID:24932138

  3. Quantitative thin layer chromatography for the analysis of skin surface lipids. A time-saving method using a new TLC plate.

    PubMed

    Weissmann, A

    1979-07-30

    Recently a new thin layer chromatography plate (Whatman LK 6D) became available which is extremely easy to handle and permits highly reproducible qualitative and quantitative analysis. This plate proved to be of great value for the investigation of skin surface lipids. The use of a fatty acid methyl ester as an internal standard makes it unnecessary to employ additional gravimetrical or photometrical methods for quanitative lipid analysis. The method presented in this paper is simpler and requires much less time than alternative procedures and allows a large number of lipid samples to be processed simultaneously. PMID:475450

  4. Altered lipid metabolism in the aging kidney identified by three layered omic analysis

    PubMed Central

    Braun, Fabian; Rinschen, Markus M.; Bartels, Valerie; Frommolt, Peter; Habermann, Bianca; Hoeijmakers, Jan H.J.; Schumacher, Björn; Dollé, Martijn E.T.; Müller, Roman-Ulrich; Benzing, Thomas; Schermer, Bernhard; Kurschat, Christine E.

    2016-01-01

    Aging-associated diseases and their comorbidities affect the life of a constantly growing proportion of the population in developed countries. At the center of these comorbidities are changes of kidney structure and function as age-related chronic kidney disease predisposes to the development of cardiovascular diseases such as stroke, myocardial infarction or heart failure. To detect molecular mechanisms involved in kidney aging, we analyzed gene expression profiles of kidneys from adult and aged wild-type mice by transcriptomic, proteomic and targeted lipidomic methodologies. Interestingly, transcriptome and proteome analyses revealed differential expression of genes primarily involved in lipid metabolism and immune response. Additional lipidomic analyses uncovered significant age-related differences in the total amount of phosphatidylethanolamines, phosphatidylcholines and sphingomyelins as well as in subspecies of phosphatidylserines and ceramides with age. By integration of these datasets we identified Aldh1a1, a key enzyme in vitamin A metabolism specifically expressed in the medullary ascending limb, as one of the most prominent upregulated proteins in old kidneys. Moreover, ceramidase Asah1 was highly expressed in aged kidneys, consistent with a decrease in ceramide C16. In summary, our data suggest that changes in lipid metabolism are involved in the process of kidney aging and in the development of chronic kidney disease. PMID:26886165

  5. Altered lipid metabolism in the aging kidney identified by three layered omic analysis.

    PubMed

    Braun, Fabian; Rinschen, Markus M; Bartels, Valerie; Frommolt, Peter; Habermann, Bianca; Hoeijmakers, Jan H J; Schumacher, Björn; Dollé, Martijn E T; Müller, Roman-Ulrich; Benzing, Thomas; Schermer, Bernhard; Kurschat, Christine E

    2016-03-01

    Aging-associated diseases and their comorbidities affect the life of a constantly growing proportion of the population in developed countries. At the center of these comorbidities are changes of kidney structure and function as age-related chronic kidney disease predisposes to the development of cardiovascular diseases such as stroke, myocardial infarction or heart failure. To detect molecular mechanisms involved in kidney aging, we analyzed gene expression profiles of kidneys from adult and aged wild-type mice by transcriptomic, proteomic and targeted lipidomic methodologies. Interestingly, transcriptome and proteome analyses revealed differential expression of genes primarily involved in lipid metabolism and immune response. Additional lipidomic analyses uncovered significant age-related differences in the total amount of phosphatidylethanolamines, phosphatidylcholines and sphingomyelins as well as in subspecies of phosphatidylserines and ceramides with age. By integration of these datasets we identified Aldh1a1, a key enzyme in vitamin A metabolism specifically expressed in the medullary ascending limb, as one of the most prominent upregulated proteins in old kidneys. Moreover, ceramidase Asah1 was highly expressed in aged kidneys, consistent with a decrease in ceramide C16. In summary, our data suggest that changes in lipid metabolism are involved in the process of kidney aging and in the development of chronic kidney disease. PMID:26886165

  6. Development of a reliable analytical method to determine lipid peroxidation biomarkers in newborn plasma samples.

    PubMed

    Cháfer-Pericás, C; Torres-Cuevas, I; Sanchez-Illana, A; Escobar, J; Kuligowski, J; Solberg, R; Garberg, H T; Huun, M U; Saugstad, O D; Vento, M

    2016-06-01

    This paper describes a reliable analytical method based on ultra-performance liquid chromatography coupled to tandem mass spectrometry to determine F2-isoprostanes and other total byproducts (isoprostanes, isofurans, neuroprostanes and neurofurans) as lipid peroxidation biomarkers in newborn plasma samples. The proposed procedure is characterized by a simple sample treatment employing a reduced sample volume (100µL). Also, it shows a high throughput and high selectivity to determine simultaneously different isoprostane isomers in a large number of samples. The reliability of the described method was demonstrated by analysis of spiked plasma samples, obtaining recoveries between 70% and 130% for most of the analytes. Taking into account the implementation of further clinical studies, it was demonstrated the proper sensitivity of the method by means of the analysis of few human newborn plasma samples. In addition to this, newborn piglet plasma samples (n=80) were analyzed observing that the developed method was suitable to determine the analyte levels present in this kind of samples. Therefore, this analytical method could be applied in further clinical research about establishment of reliable lipid peroxidation biomarkers employing this experimental model. PMID:27130102

  7. Development of the layer-by-layer biosensor using graphene films: application for cholesterol determination

    NASA Astrophysics Data System (ADS)

    Binh Nguyen, Hai; Chuc Nguyen, Van; Nguyen, Van Tu; Doan Le, Huu; Quynh Nguyen, Van; Thanh Tam Ngo, Thi; Phuc Do, Quan; Nghia Nguyen, Xuan; Phan, Ngoc Minh; Tran, Dai Lam

    2013-03-01

    The preparation and characterization of graphene films for cholesterol determination are described. The graphene films were synthesized by thermal chemical vapor deposition (CVD) method. Methane gas (CH4) and copper tape were used as carbon source and catalyst in the graphene growth process, respectively. The intergrated array was fabricated by using micro-electro-mechanical systems (MEMS) technology in which Fe3O4-doped polyaniline (PANi) film was electropolymerized on Pt/Gr electrodes. The properties of the Pt/Gr/PANi/Fe3O4 films were investigated by field-emission scanning electron microscopy (FE-SEM), Raman spectroscopy and electrochemical techniques. Cholesterol oxidase (ChOx) has been immobilized onto the working electrode with glutaraldehyde agent. The cholesterol electrochemical biosensor shows high sensitivity (74 μA mM-1 cm-2) and fast response time (<5 s). A linear calibration plot was obtained in the wide cholesterol concentration range from 2 to 20 mM and correlation coefficient square (R2) of 0.9986. This new layer-by-layer biosensor based on graphene films promises many practical applications.

  8. Super-resolved thickness maps of thin film phantoms and in vivo visualization of tear film lipid layer using OCT

    PubMed Central

    dos Santos, Valentin Aranha; Schmetterer, Leopold; Triggs, Graham J.; Leitgeb, Rainer A.; Gröschl, Martin; Messner, Alina; Schmidl, Doreen; Garhofer, Gerhard; Aschinger, Gerold; Werkmeister, René M.

    2016-01-01

    In optical coherence tomography (OCT), the axial resolution is directly linked to the coherence length of the employed light source. It is currently unclear if OCT allows measuring thicknesses below its axial resolution value. To investigate spectral-domain OCT imaging in the super-resolution regime, we derived a signal model and compared it with the experiment. Several island thin film samples of known refractive indices and thicknesses in the range 46 – 163 nm were fabricated and imaged. Reference thickness measurements were performed using a commercial atomic force microscope. In vivo measurements of the tear film were performed in 4 healthy subjects. Our results show that quantitative super-resolved thickness measurement can be performed using OCT. In addition, we report repeatable tear film lipid layer visualization. Our results provide a novel interpretation of the OCT axial resolution limit and open a perspective to deeper extraction of the information hidden in the coherence volume. PMID:27446696

  9. Super-resolved thickness maps of thin film phantoms and in vivo visualization of tear film lipid layer using OCT.

    PubMed

    Dos Santos, Valentin Aranha; Schmetterer, Leopold; Triggs, Graham J; Leitgeb, Rainer A; Gröschl, Martin; Messner, Alina; Schmidl, Doreen; Garhofer, Gerhard; Aschinger, Gerold; Werkmeister, René M

    2016-07-01

    In optical coherence tomography (OCT), the axial resolution is directly linked to the coherence length of the employed light source. It is currently unclear if OCT allows measuring thicknesses below its axial resolution value. To investigate spectral-domain OCT imaging in the super-resolution regime, we derived a signal model and compared it with the experiment. Several island thin film samples of known refractive indices and thicknesses in the range 46 - 163 nm were fabricated and imaged. Reference thickness measurements were performed using a commercial atomic force microscope. In vivo measurements of the tear film were performed in 4 healthy subjects. Our results show that quantitative super-resolved thickness measurement can be performed using OCT. In addition, we report repeatable tear film lipid layer visualization. Our results provide a novel interpretation of the OCT axial resolution limit and open a perspective to deeper extraction of the information hidden in the coherence volume. PMID:27446696

  10. Virosome engineering of colloidal particles and surfaces: bioinspired fusion to supported lipid layers

    NASA Astrophysics Data System (ADS)

    Fleddermann, J.; Diamanti, E.; Azinas, S.; Košutić, M.; Dähne, L.; Estrela-Lopis, I.; Amacker, M.; Donath, E.; Moya, S. E.

    2016-04-01

    Immunostimulating reconstituted influenza virosomes (IRIVs) are liposomes with functional viral envelope glycoproteins: influenza virus hemagglutinin (HA) and neuraminidase intercalated in the phospholipid bilayer. Here we address the fusion of IRIVs to artificial supported lipid membranes assembled on polyelectrolyte multilayers on both colloidal particles and planar substrates. The R18 assay is used to prove the IRIV fusion in dependence of pH, temperature and HA concentration. IRIVs display a pH-dependent fusion mechanism, fusing at low pH in analogy to the influenza virus. The pH dependence is confirmed by the Quartz Crystal Microbalance technique. Atomic Force Microscopy imaging shows that at low pH virosomes are integrated in the supported membrane displaying flattened features and a reduced vertical thickness. Virosome fusion offers a new strategy for transferring biological functions on artificial supported membranes with potential applications in targeted delivery and sensing.Immunostimulating reconstituted influenza virosomes (IRIVs) are liposomes with functional viral envelope glycoproteins: influenza virus hemagglutinin (HA) and neuraminidase intercalated in the phospholipid bilayer. Here we address the fusion of IRIVs to artificial supported lipid membranes assembled on polyelectrolyte multilayers on both colloidal particles and planar substrates. The R18 assay is used to prove the IRIV fusion in dependence of pH, temperature and HA concentration. IRIVs display a pH-dependent fusion mechanism, fusing at low pH in analogy to the influenza virus. The pH dependence is confirmed by the Quartz Crystal Microbalance technique. Atomic Force Microscopy imaging shows that at low pH virosomes are integrated in the supported membrane displaying flattened features and a reduced vertical thickness. Virosome fusion offers a new strategy for transferring biological functions on artificial supported membranes with potential applications in targeted delivery and sensing

  11. MEASUREMENTS OF CONFORMATION CHANGES DURING ADHESION OF LIPID PROTEIN (POLYLYSINE AND S-LAYER) SURFACES

    EPA Science Inventory

    The adhesion forces between various surfaces were measured using the "surface forces apparatus" technique which allows for the thickness of surface layers and the adhesion force between them to be directly measured in controlled vapor or liquid environments. hree types of biologi...

  12. Determination of layer-charge characteristics of smectites

    USGS Publications Warehouse

    Christidis, G.E.; Eberl, D.D.

    2003-01-01

    A new method for calculation of layer charge and charge distribution of smectites is proposed. The method is based on comparisons between X-ray diffraction (XRD) patterns of K-saturated, ethylene glycol-solvated, oriented samples and calculated XRD patterns for three-component, mixed-layer systems. For the calculated patterns it is assumed that the measured patterns can be modeled as random interstratifications of fully expanding 17.1 A?? layers, partially expanding 13.5 A?? layers and non-expanding 9.98 A?? layers. The technique was tested using 29 well characterized smectites. According to their XRD patterns, smectites were classified as group 1 (low-charge smectites) and group 2 (high-charge smectites). The boundary between the two groups is at a layer charge of -0.46 equivalents per half unit-cell. Low-charge smectites are dominated by 17.1 A?? layers, whereas high-charge smectites contain only 20% fully expandable layers on average. Smectite properties and industrial applications may be dictated by the proportion of 17.1 A?? layers present. Non-expanding layers may control the behavior of smectites during weathering, facilitating the formation of illite layers after subsequent cycles of wetting and drying. The precision of the method is better than 3.5% at a layer charge of -0.50; therefore the method should be useful for basic research and for industrial purposes.

  13. Square Wave Voltammetry: An Alternative Technique to Determinate Piroxicam Release Profiles from Nanostructured Lipid Carriers.

    PubMed

    Otarola, Jessica; Garrido, Mariano; Correa, N Mariano; Molina, Patricia G

    2016-08-01

    A new, simple, and fast electrochemical (EC) method has been developed to determine the release profile of piroxicam, a nonsteroidal anti-inflammatory drug, loaded in a drug delivery system based on nanostructured lipid carriers (NLCs). For the first time, the samples were analyzed by using square wave voltammetry, a sensitive EC technique. The piroxicam EC responses allow us to propose a model that explains the experimental results and to subsequently determine the amount of drug loaded into the NLCs formulation as a function of time. In vitro drug release studies showed prolonged drug release (up to 5 days), releasing 60 % of the incorporated drug. The proposed method is a promising and stable alternative for the study of different drug delivery systems. PMID:27128856

  14. The Effect of Particle Size on the Deposition of Solid Lipid Nanoparticles in Different Skin Layers: A Histological Study

    PubMed Central

    Mardhiah Adib, Zahra; Ghanbarzadeh, Saeed; Kouhsoltani, Maryam; Yari Khosroshahi, Ahmad; Hamishehkar, Hamed

    2016-01-01

    Purpose: In the present study the effect of particle size, as a substantial parameters in skin penetration, on the deposition depth and rate of SLNs in different layers of skin was explored. Methods: SLNs in different particle size ranges (80, 333 and 971 nm) made of Precirol as solid lipid were prepared using hot melt homogenization technique and pigmented by Rhodamine B to be able to be tracked in the skin under inspection of fluorescent microscopy. After 0.5 h, 3 h, 6 h and 24 h of SLNs administration on rat skin, animals were sacrificed and exercised skins were sliced by a freeze microtome. SLNs were monitored in the skin structure under fluorescence microscope. Results: The size of SLNs played a crucial role in the penetration to deep skin layers. The sub100 nm size range of SLNs showed the most promising skin penetration rate and depth mainly via hair follicles. Conclusion: The results of the present study indicated that the selection of an appropriate size of particles may be a valuable factor impacting the therapeutic outcomes of dermal drug administration. PMID:27123415

  15. Isolation and identification of chloroplast lipids.

    PubMed

    Sato, Norihiro; Tsuzuki, Mikio

    2011-01-01

    Glycerolipids of photosynthetic organisms are accounted for largely by thylakoid membrane lipids consisting of chloroplast-specific glycolipids such as monogalactosyl diacylglycerol, digalactosyl diacylglycerol, and sulfoquinovosyl diacylglycerol, and a sole phospholipid, phosphatidylglycerol. In this chapter, methods for characterization of lipids from plant cells are described. The methods include extraction of total lipids from the cells, separation of these lipids into individual lipid classes by thin-layer chromatography, and identification of respective lipid classes by their mobility. We also present methods for the determination of compositions of constituent fatty acids, distribution of fatty acids between sn-1 and sn-2 positions, and determination of contents of individual lipid classes by gas-liquid chromatography. These methods are applicable to isolated chloroplasts or some membrane fractions such as thylakoid membranes. PMID:20960124

  16. Consumption of dietary sugar by gut bacteria determines Drosophila lipid content.

    PubMed

    Huang, Jia-Hsin; Douglas, Angela E

    2015-09-01

    Gut microorganisms are essential for the nutritional health of many animals, but the underlying mechanisms are poorly understood. This study investigated how lipid accumulation by adult Drosophila melanogaster is reduced in flies associated with the bacterium Acetobacter tropicalis which displays oral-faecal cycling between the gut and food. We demonstrate that the lower lipid content of A. tropicalis-colonized flies relative to bacteria-free flies is linked with a parallel bacterial-mediated reduction in food glucose content; and can be accounted for quantitatively by the amount of glucose acquired by the flies, as determined from the feeding rate and assimilation efficiency of bacteria-free and A. tropicalis-colonized flies. We recommend that nutritional studies on Drosophila include empirical quantification of food nutrient content, to account for likely microbial-mediated effects on diet composition. More broadly, this study demonstrates that selective consumption of dietary constituents by microorganisms can alter the nutritional balance of food and, thereby, influence the nutritional status of the animal host. PMID:26382071

  17. Formulation and In Vitro and In Vivo Evaluation of Lipid-Based Terbutaline Sulphate Bi-layer Tablets for Once-Daily Administration.

    PubMed

    Hashem, Fahima M; Nasr, Mohamed; Fathy, Gihan; Ismail, Aliaa

    2016-06-01

    The objective of this study was to prepare and evaluate terbutaline sulphate (TBS) bi-layer tablets for once-daily administration. The bi-layer tablets consisted of an immediate-release layer and a sustained-release layer containing 5 and 10 mg TBS, respectively. The sustained-release layer was developed by using Compritol®888 ATO, Precirol® ATO 5, stearic acid, and tristearin, separately, as slowly eroding lipid matrices. A full 4 × 2(2) factorial design was employed for optimization of the sustained-release layer and to explore the effect of lipid type (X 1), drug-lipid ratio (X 2), and filler type (X 3) on the percentage drug released at 8, 12, and 24 h (Y 1, Y 2, and Y 3) as dependent variables. Sixteen TBS sustained-release matrices (F1-F16) were prepared by melt solid dispersion method. None of the prepared matrices achieved the targeted release profile. However, F2 that showed a relatively promising drug release was subjected to trial and error optimization for the filler composition to develop two optimized matrices (F17 and F18). F18 which consisted of drug-Compritol®888 ATO at ratio (1:6 w/w) and Avicel PH 101/dibasic calcium phosphate mixture of 2:1 (w/w) was selected as sustained-release layer. TBS bi-layer tablets were evaluated for their physical properties, in vitro drug release, effect of storage on drug content, and in vivo performance in rabbits. The bi-layer tablets showed acceptable physical properties and release characteristics. In vivo absorption in rabbits revealed initial high TBS plasma levels followed by sustained levels over 24 h compared to immediate-release tablets. PMID:26335420

  18. Determination of orientational order parameters from 2H NMR spectra of magnetically partially oriented lipid bilayers.

    PubMed Central

    Schäfer, H; Mädler, B; Sternin, E

    1998-01-01

    The partial orientation of multilamellar vesicles (MLVs) in high magnetic fields is known to affect the shape of 2H NMR spectra. There are numerical methods for extracting either the orientational order parameters of lipid molecules for a random distribution of domain orientations in the sample, or the distribution of orientations for a known set of spectral anisotropies. A first attempt at determining the orientational order parameters in the presence of an unknown nonrandom distribution of orientations is presented. The numerical method is based on the Tikhonov regularization algorithm. It is tested using simulated partially oriented spectra. An experimental spectrum of a phospholipid-ether mixture in water is analyzed as an example. The experimental spectrum is consistent with an ellipsoidal shape of MLVs with a ratio of semiaxes of approximately 3.4. PMID:9533713

  19. A field effect transistor biosensor with a γ-pyrone derivative engineered lipid-sensing layer for ultrasensitive Fe3+ ion detection with low pH interference.

    PubMed

    Nguyen, Tuyen D; Labed, Abdelfettah; El Zein, Racha; Lavandier, Sébastien; Bedu, Fréderic; Ozerov, Igor; Dallaporta, Hervé; Raimundo, Jean-Manuel; Charrier, Anne M

    2014-04-15

    Field effect transistors have risen as one of the most promising techniques in the development of biomedical diagnosis and monitoring. In such devices, the sensitivity and specificity of the sensor rely on the properties of the active sensing layer (gate dielectric and probe layer). We propose here a new type of transistor developed for the detection of Fe(3+) ions in which this sensing layer is made of a monolayer of lipids, engineered in such a way that it is not sensitive to pH in the acidic range, therefore making the device perfectly suitable for biomedical diagnosis. Probes are γ-pyrone derivatives that have been grafted to the lipid headgroups. Affinity constants derived for the chelator/Fe(3+) complexation as well as for other ions demonstrate very high sensitivity and specificity towards ferric ions with values as high as 5.10(10) M and a detected concentration as low as 50 fM. PMID:24333568

  20. Determination of layer-thickness variation in periodic multilayer by x-ray reflectivity

    SciTech Connect

    Jiang Hui; Zhu Jingtao; Xu Jing; Wang Xiaoqiang; Wang Zhanshan; Watanabe, Makoto

    2010-05-15

    A method basically determining individual layer thicknesses in actual periodic multilayers has been developed, that solves simultaneous equations of positions of peaks appearing in wavelet transform curve of x-ray grazing incidence reflectivity. The determination was demonstrated on a Ni/C periodic multilayer fabricated by magnetron sputtering. Using the layer thicknesses obtained by the method, further accurate of thickness, roughness, and density of each layer was performed by Parratt's model. The special feature that the topmost and bottom-most layers were thicker than other layers was clearly observed. The former is attributed to oxidation and the latter is attributed to the effect of deposition on thick substrate. The mean fluctuations of other layers are 2.6% in C layers and 4.2% in Ni layers attributed to random fluctuations at deposition. Numerical analysis and statistical hypothesis tests have been carried out to discuss noncumulative and cumulative layer-thickness fluctuations in fabrication process.

  1. Application of FTIR-ATR Spectroscopy to Determine the Extent of Lipid Peroxidation in Plasma during Haemodialysis

    PubMed Central

    Oleszko, Adam; Olsztyńska-Janus, Sylwia; Grzeszczuk-Kuć, Karolina; Bujok, Jolanta; Gałecka, Katarzyna; Czerski, Albert; Witkiewicz, Wojciech; Komorowska, Małgorzata

    2015-01-01

    During a haemodialysis (HD), because of the contact of blood with the surface of the dialyser, the immune system becomes activated and reactive oxygen species (ROS) are released into plasma. Particularly exposed to the ROS are lipids and proteins contained in plasma, which undergo peroxidation. The main breakdown product of oxidized lipids is the malondialdehyde (MDA). A common method for measuring the concentration of MDA is a thiobarbituric acid reactive substances (TBARS) method. Despite the formation of MDA in plasma during HD, its concentration decreases because it is removed from the blood in the dialyser. Therefore, this research proposes the Fourier Transform Infrared Attenuated Total Reflectance (FTIR-ATR) spectroscopy, which enables determination of primary peroxidation products. We examined the influence of the amount of hydrogen peroxide added to lipid suspension that was earlier extracted from plasma specimen on lipid peroxidation with use of TBARS and FTIR-ATR methods. Linear correlation between these methods was shown. The proposed method was effective during the evaluation of changes in the extent of lipid peroxidation in plasma during a haemodialysis in sheep. A measurement using the FTIR-ATR showed an increase in plasma lipid peroxidation after 15 and 240 minutes of treatment, while the TBARS concentration was respectively lower. PMID:25961007

  2. Resistance of Gram-positive bacteria to nisin is not determined by lipid II levels.

    PubMed

    Kramer, Naomi E; Smid, Eddy J; Kok, Jan; de Kruijff, Ben; Kuipers, Oscar P; Breukink, Eefjan

    2004-10-01

    Lipid II is essential for nisin-mediated pore formation at nano-molar concentrations. We tested whether nisin resistance could result from different Lipid II levels, by comparing the maximal Lipid II pool in Micrococcus flavus (sensitive) and Listeria monocytogenes (relatively insensitive) and their nisin-resistant variants, with a newly developed method. No correlation was observed between the maximal Lipid II pool and nisin sensitivity, as was further corroborated by using spheroplasts of nisin-resistant and wild-type strains of M. flavus, which were equally sensitive to nisin. PMID:15451114

  3. Distribution of Lipids in the Grain of Wheat (cv. Hereward) Determined by Lipidomic Analysis of Milling and Pearling Fractions.

    PubMed

    González-Thuillier, Irene; Salt, Louise; Chope, Gemma; Penson, Simon; Skeggs, Peter; Tosi, Paola; Powers, Stephen J; Ward, Jane L; Wilde, Peter; Shewry, Peter R; Haslam, Richard P

    2015-12-16

    Lipidomic analyses of milling and pearling fractions from wheat grain were carried out to determine differences in composition that could relate to the spatial distribution of lipids in the grain. Free fatty acids and triacylglycerols were major components in all fractions, but the relative contents of polar lipids varied, particularly those of lysophosphatidylcholine and digalactosyldiglyceride, which were enriched in flour fractions. By contrast, minor phospholipids were enriched in bran and offal fractions. The most abundant fatty acids in the analyzed acyl lipids were C16:0 and C18:2 and their combinations, including C36:4 and C34:2. Phospholipids and galactolipids have been reported to have beneficial properties for breadmaking, whereas free fatty acids and triacylglycerols are considered detrimental. The subtle differences in the compositions of fractions determined in the present study could therefore underpin the production of flour fractions with optimized compositions for different end uses. PMID:26582143

  4. Lipid polyunsaturation determines the extent of membrane structural changes induced by Amphotericin B in Pichia pastoris yeast.

    PubMed

    de Ghellinck, Alexis; Fragneto, Giovanna; Laux, Valerie; Haertlein, Michael; Jouhet, Juliette; Sferrazza, Michele; Wacklin, Hanna

    2015-10-01

    The activity of the potent but highly toxic antifungal drug Amphotericin B (AmB), used intravenously to treat systemic fungal and parasitic infections, is widely accepted to result from its specific interaction with the fungal sterol ergosterol. While the effect of sterols on AmB activity has been intensely investigated, the role of membrane phospholipid composition has largely been ignored, and structural studies of native membranes have been hampered by their complex and disordered nature. We show for the first time that the structure of fungal membranes derived from Pichia pastoris yeast depends on the degree of lipid polyunsaturation, which has an impact on the structural consequences of AmB activity. AmB inserts in yeast membranes even in the absence of ergosterol, and forms an extra-membraneous layer whose thickness is resolved to be 4-5 nm. In ergosterol-containing membranes, AmB insertion is accompanied by ergosterol extraction into this layer. The AmB-sponge mediated depletion of ergosterol from P. pastoris membranes gives rise to a significant membrane thinning effect that depends on the degree of lipid polyunsaturation. The resulting hydrophobic mismatch is likely to interfere with a much broader range of membrane protein functions than those directly involving ergosterol, and suggests that polyunsaturated lipids could boost the efficiency of AmB. Furthermore, a low degree of lipid polyunsaturation leads to least AmB insertion and may protect host cells against the toxic effects of AmB. These results provide a new framework based on lipid composition and membrane structure through which we can understand its antifungal action and develop better treatments. PMID:26055896

  5. Determination of Stability and Translation in a Boundary Layer

    NASA Technical Reports Server (NTRS)

    Crepeau, John; Tobak, Murray

    1996-01-01

    Reducing the infinite degrees of freedom inherent in fluid motion into a manageable number of modes to analyze fluid motion is presented. The concepts behind the center manifold technique are used. Study of the Blasius boundary layer and a precise description of stability within the flow field are discussed.

  6. Desorption electrospray ionization mass spectrometry analysis of lipids after two-dimensional high-performance thin-layer chromatography partial separation

    PubMed Central

    Paglia, Giuseppe; Ifa, Demian R.; Wu, Chunping; Corso, Gaetano; Cooks, R. Graham

    2010-01-01

    Molecular imaging of separate but still incompletely resolved spots on high-performance thin-layer chromatography (HPTLC) plates is used for the direct analysis of porcine brain lipids by desorption electrospray ionization mass spectrometry (DESI-MS). Seven class-specific spots were imaged in the negative ion mode and shown to contain more than fifty lipids. A low lateral resolution of 400 × 400 μm allowed simple, rapid and incomplete separation to be combined with DESI imaging for the identification of many components of these extremely complex mixtures. In this work, tandem mass spectrometry (MS/MS) was also employed to confirm the identity of particular lipids directly on HPTLC plates. PMID:20128616

  7. Optimization of a Nile Red method for rapid lipid determination in autotrophic, marine microalgae is species dependent.

    PubMed

    Balduyck, Lieselot; Veryser, Cedrick; Goiris, Koen; Bruneel, Charlotte; Muylaert, Koenraad; Foubert, Imogen

    2015-11-01

    Several studies have been conducted to develop rapid methods for quantification of lipid content in microalgae, as an alternative for time consuming gravimetric methods. Different studies showed that lipid staining with Nile Red in whole cell suspensions and subsequently quantification by the use of a spectrofluorometric device is a promising method, but a profound optimization and validation is rare. It has already been proven that the correlation curve for quantification is species dependent, but it has not yet been investigated whether this is also the case for the optimization of the Nile Red assay protocol. Therefore, two autotrophic, marine microalgae, Nannochloropsis oculata and T-Isochrysis lutea, strongly differing in e.g. cell wall structure, were selected in this study to investigate whether optimization of the Nile Red assay is species dependent. Besides this, it was checked for one of these species, Nannochloropsis, whether the lipid content, determined by the Nile Red assay, could indeed be correlated with the neutral and/or total lipid content determined by gravimetric methods. It was found that optimization of the Nile Red assay was strongly species dependent. Consequently, optimization has to be done for each species before using the assay. For Nannochloropsis, a good correlation was found between total and neutral lipid content obtained by the Nile Red assay and by gravimetric methods. PMID:26388510

  8. Using fluorescence-activated flow cytometry to determine reactive oxygen species formation and membrane lipid peroxidation in viable boar spermatozoa

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fluorescence-activated flow cytometry analyses were developed for determination of reactive oxygen species (ROS) formation and membrane lipid peroxidation in live spermatozoa loaded with, respectively, hydroethidine (HE) or the lipophilic probe 4,4-difluoro-5-(4-phenyl-1,3-butadienyl)-4-bora-3a,4a-d...

  9. Evaluation of micro-colorimetric lipid determination method with samples prepared using sonication and accelerated solvent extraction methods

    EPA Science Inventory

    Two common laboratory extraction techniques were evaluated for routine use with the micro-colorimetric lipid determination method developed by Van Handel (1985) [E. Van Handel, J. Am. Mosq. Control Assoc. 1(1985) 302] and recently validated for small samples by Inouye and Lotufo ...

  10. Micro-porous layer stochastic reconstruction and transport parameter determination

    NASA Astrophysics Data System (ADS)

    El Hannach, Mohamed; Singh, Randhir; Djilali, Ned; Kjeang, Erik

    2015-05-01

    The Micro-Porous Layer (MPL) is a porous, thin layer commonly used in fuel cells at the interfaces between the catalyst layers and gas diffusion media. It is generally made from spherical carbon nanoparticles and PTFE acting as hydrophobic agent. The scale and brittle nature of the MPL structure makes it challenging to study experimentally. In the present work, a 3D stochastic model is developed to virtually reconstruct the MPL structure. The carbon nanoparticle and PTFE phases are fully distinguished by the algorithm. The model is shown to capture the actual structural morphology of the MPL and is validated by comparing the results to available experimental data. The model shows a good capability in generating a realistic MPL successfully using a set of parameters introduced to capture specific morphological features of the MPL. A numerical model that resolves diffusive transport at the pore scale is used to compute the effective transport properties of the reconstructed MPLs. A parametric study is conducted to illustrate the capability of the model as an MPL design tool that can be used to guide and optimize the functionality of the material.

  11. Development of novel fluorescent probe 3-perylene diphenylphosphine for determination of lipid hydroperoxide with fluorescent image analysis

    SciTech Connect

    Chotimarkorn, Chatchawan; Nagasaka, Reiko; Ushio, Hideki . E-mail: hushio@s.kaiyodai.ac.jp; Ohshima, Toshiaki; Matsunaga, Shigeki

    2005-12-16

    A novel fluorescent probe 3-perylene diphenylphosphine (3-PeDPP) was synthesized for the direct analysis of lipid hydroperoxides. The structure of 3-PeDPP was identified by the spectroscopic data, FAB-MS, {sup 1}H NMR, and {sup 13}C NMR. The reactivities of 3-PeDPP with lipid hydroperoxides were investigated in chloroform/MeOH homogeneous solutions and PC liposome model systems oxidized by either 2,2'-azobis(2-amidinopropane)dihydrochloride and photosensitized oxidation. The fluorescence intensity derived from 3-perylene diphenylphosphineoxide (3-PeDPPO) increased proportionally with amount of hydroperoxides produced in homogeneous solutions and liposome model systems. 3-PeDPP was easily incorporated into mouse myeloma SP2 cells and thin tissue section for dynamic membrane lipid peroxidation studies. Linear correlations between fluorescence intensity and amount of hydroperoxides in the cell membrane and tissue sections were obtained. The fluorescence intensity from 2-dimensional image analysis was also well correlated with lipid hydroperoxide level in these models. Thus, the novel probe 3-PeDPP is useful for the direct determination of lipid hydroperoxides in biological materials.

  12. Evaluation of micro-colorimetric lipid determination method with samples prepared using sonication and accelerated solvent extraction methods.

    PubMed

    Billa, Nanditha; Hubin-Barrows, Dylan; Lahren, Tylor; Burkhard, Lawrence P

    2014-02-01

    Two common laboratory extraction techniques were evaluated for routine use with the micro-colorimetric lipid determination method developed by Van Handel (1985) [2] and recently validated for small samples by Inouye and Lotufo (2006) [1]. With the accelerated solvent extraction method using chloroform:methanol solvent and the colorimetric lipid determination method, 28 of 30 samples had significant proportional bias (α=1%, determined using standard additions) and 1 of 30 samples had significant constant bias (α=1%, determined using Youden Blank measurements). With sonic extraction, 0 of 6 samples had significant proportional bias (α=1%) and 1 of 6 samples had significant constant bias (α=1%). These demonstrate that the accelerated solvent extraction method with chloroform:methanol solvent system creates an interference with the colorimetric assay method, and without accounting for the bias in the analysis, inaccurate measurements would be obtained. PMID:24401464

  13. [Thin-layer chromatographic determination of coumarin derivatives].

    PubMed

    Tsvetkova, Ts M

    1977-01-01

    Described is a thin-layer chromatography method for the demonstration and identification of the cumarin derivatives cumaphos and warfarin. Tested were five solvents and six developers. Best results were obtained by means of Silica gel plates, the toluol-aceton solvent (85:15), and the developer of a diazosalt 0.4% in an alcohol 20% sodiumhydroxide. Warfarin and cumaphos are demonstrated with the appearance of yellow, resp. orange spots on a white background, the RF values being 0.37 and 0.85, and sensitivity as regards warfarin 0.5 microgram and cumaphos 0.2 microgram. PMID:898648

  14. Local structure determination in strained-layer semiconductors

    NASA Astrophysics Data System (ADS)

    Woicik, Joseph C.

    The theory of elasticity accurately describes the deformations of macroscopic bodies under the action of applied stress [1]. In this review, we examine the internal mechanisms of elasticity for strained-layer semiconductor heterostructures. In particular, we present extended x-ray-absorption fine structure (EXAFS) and x-ray diffraction (XRD) measurements to show how the bond lengths and bond angles in semiconductor thin-alloy films change with strain when they are grown coherently on substrates with different lattice constants. The structural distortions measured by experiment are compared to valence-force field (VFF) calculations and other theoretical models. Atomic switching and interfacial strain at buried interfaces are also discussed.

  15. Utility of genetic determinants of lipids and cardiovascular events in assessing risk.

    PubMed

    Holmes, Michael V; Harrison, Seamus; Talmud, Philippa J; Hingorani, Aroon D; Humphries, Steve E

    2011-04-01

    The prevention of coronary heart disease (CHD) is a major public-health goal, but disease architecture is such that a larger proportion of clinical events occur among the average majority than among the high-risk minority--the prevention paradox. Genetic findings over the past few years have resulted in the reopening of the old debate on whether an individualized or a population-based approach to prevention is preferable. Genetic testing is an attractive tool for CHD risk prediction because it is a low-cost, high-fidelity technology with multiplex capability. Moreover, by contrast with nongenetic markers, genotype is invariant and determined from conception, which eliminates biological variability and makes prediction from early life possible. Mindful of the prevention paradox, this Review examines the potential applications and challenges of using genetic information for predicting CHD, focusing on lipid risk factors and drawing on experience in the evaluation of nongenetic risk factors as screening tests for CHD. Many of the issues we discuss hold true for any late-onset common disease with modifiable risk factors and proven preventative strategies. PMID:21321562

  16. The modified fluorescence based vesicle fluctuation spectroscopy technique for determination of lipid bilayer bending properties.

    PubMed

    Drabik, Dominik; Przybyło, Magda; Chodaczek, Grzegorz; Iglič, Aleš; Langner, Marek

    2016-02-01

    Lipid bilayer is the main constitutive element of biological membrane, which confines intracellular space. The mechanical properties of biological membranes may be characterized by various parameters including membrane stiffness or membrane bending rigidity, which can be measured using flicker noise spectroscopy. The flicker noise spectroscopy exploits the spontaneous thermal undulations of the membrane. The method is based on the quantitative analysis of a series of microscopic images captured during thermal membrane fluctuations. Thus, measured bending rigidity coefficient depends on the image quality as well as the selection of computational tools for image processing and mathematical model used. In this work scanning and spinning disc confocal microscopies were used to visualize fluctuating membranes of giant unilamellar vesicles. The bending rigidity coefficient was calculated for different acquisition modes, using different fluorescent probes and different image processing methods. It was shown that both imaging approaches gave similar bending coefficient values regardless of acquisition time. Using the developed methodology the effect of fluorescent probe type and aqueous phase composition on the value of the membrane bending rigidity coefficient was measured. Specifically it was found that the bending rigidity coefficient of DOPC bilayer in water is smaller than that determined for POPC membrane. It has been found that the POPC and DOPC bending rigidities coefficient in sucrose solution was lower than that in water. Fluorescence imaging makes possible the quantitative analysis of membrane mechanical properties of inhomogeneous membrane. PMID:26615919

  17. Membrane Protein Structure Determination Using Crystallography and Lipidic Mesophases - Recent Advances and Successes

    PubMed Central

    Caffrey, Martin; Li, Dianfan; Dukkipati, Abhiram

    2012-01-01

    The crystal structure of the β2-adrenergic receptor in complex with an agonist and its cognate G protein has just recently been solved. It is now possible to explore in molecular detail the means by which this paradigmatic transmembrane receptor binds agonist, communicates the impulse or signalling event across the membrane and sets in motion a series of G protein-directed intracellular responses. The structure was determined using crystals of the ternary complex grown in a rationally designed lipidic mesophase by the so-called in meso method. The method is proving to be particularly useful in the G protein-coupled receptor field where the structures of thirteen distinct receptor types have been solved in the past five years. In addition to receptors, the method has proven useful with a wide variety of integral membrane protein classes that include bacterial and eukaryotic rhodopsins, a light harvesting complex II (LHII), photosynthetic reaction centers, cytochrome oxidases, β-barrels, an exchanger, and an integral membrane peptide. This attests to the versatility and range of the method and supports the view that the in meso method should be included in the arsenal of the serious membrane structural biologist. For this to happen however, the reluctance in adopting it attributable, in part, to the anticipated difficulties associated with handling the sticky, viscous cubic mesophase in which crystals grow must be overcome. Harvesting and collecting diffraction data with the mesophase-grown crystals is also viewed with some trepidation. It is acknowledged that there are challenges associated with the method. Over the years, we have endeavored to establish how the method works at a molecular level and to make it user-friendly. To these ends, tools for handling the mesophase in the pico- to nano-liter volume range have been developed for highly efficient crystallization screening in manual and robotic modes. Methods have been implemented for evaluating the functional

  18. Determination of Components in Beverages by Thin-Layer Chromatography.

    ERIC Educational Resources Information Center

    Ma, Yinfa; Yeung, Edward S.

    1990-01-01

    Described is a simple and interesting chromatography experiment using three different fluorescence detection principles for the determination of caffeine, saccharin and sodium benzoate in beverages. Experimental procedures and an analysis and discussion of the results are included. (CW)

  19. Structure determination of a quartet of novel tetraether lipids from Methanobacterium thermoautotrophicum.

    PubMed

    Nishihara, M; Morii, H; Koga, Y

    1987-04-01

    The structures of three of the major polar lipids (PNL1a, GL1a, and PNGL1) of Methanobacterium thermoautotrophicum were elucidated. These lipids are derivatives of dibiphytanyl diglycerol tetraether (C40 tetraether; the proposed name is caldarchaeol). PNL1a is a C40 tetraether analog of phosphatidylethanolamine (proposed name: caldarchaetidylethanolamine). GL1a was identified as beta-D-glucopyranosyl-(1-6)-beta-D-glucopyranosyl C40 tetraether (diglucosyl caldarchaeol). PNGL1 has the polar head groups of both PNL1a and GL1a; one of the free hydroxyls of this tetraether is esterified with phosphoethanolamine while the other is linked to a glucosylglucose residue with the same structure as that of GL1a (proposed name: diglucosyl caldarchaetidylethanolamine). That is, PNL1a (aminophospholipid), GL1a (glycolipid), and PNGL1 (aminophosphoglycolipid) form structurally a quartet of lipids with the bare caldarchaeol. We propose a new systematic nomenclature of archaebacterial polar lipids in the "DISCUSSION," because the alternative names are too lengthy and laboratory designations of these lipids are not at all systematic. This nomenclature starts with giving the names archaeol and caldarchaeol to dialkyl diether of glycerol or other polyol and tetraether of glycerol or other polyol and alkyl alcohols, respectively, because these lipids are specific to archaebacteria. Phospholipids with a phosphodiester bond were named as derivatives of archaetidic acid or caldarchaetidic acid (phosphomonoesters of archaeol and caldarchaeol) by analogy with phosphatidic acid. PMID:3611039

  20. NMR techniques for determination of lipid content in microalgal biomass and their use in monitoring the cultivation with biodiesel potential.

    PubMed

    Sarpal, Amarjit S; Teixeira, Cláudia M L L; Silva, Paulo Roque Martins; da Costa Monteiro, Thays Vieira; da Silva, Júlia Itacolomy; da Cunha, Valnei Smarcaro; Daroda, Romeu José

    2016-03-01

    In the present investigation, the application of NMR spectroscopic techniques was extensively used with an objective to explore the biodiesel potential of biomass cultivated on a lab scale using strains of Chlorella vulgaris and Scenedesmus ecornis. The effect of variation in the composition of culturing medium on the neutral and polar lipids productivity, and fatty acid profile of solvent extracts of microalgae biomass was studied. Determination of unsaturated fatty acid composition (C18:N = 1-3, ω3 C20:5, ω3 C22:6), polyunsaturated fatty esters (PUFEs), saturated fatty acids (SFAs), unsaturated fatty acids (UFAs), free fatty acids (FFAs), and iodine value were achieved from a single (1)H NMR spectral analysis. The results were validated by (13)C NMR and GC-MS analyses. It was demonstrated that newly developed methods based on (1)H and (13)C NMR techniques are direct, rapid, and convenient for monitoring the microalgae cultivation process for enhancement of lipid productivity and their quality aspects in the solvent extracts of microalgal biomasses without any sample treatment and prior separation compared to other methods. The fatty acid composition of algae extracts was found to be similar to vegetable and fish oils, mostly rich in C16:0, C18:N (N = 0 to 3), and n-3 omega polyunsaturated fatty acids (PUFAs). The lipid content, particularly neutral lipids, as well as most of the quality parameters were found to be medium specific by both the strains. The newly developed methods based on NMR and ultrasonic procedure developed for efficient extraction of neutral lipids are cost economic and can be an effective aid for rapid screening of algae strains for modulation of lipid productivity with desired biodiesel quality and value-added products including fatty acid profile. PMID:26615401

  1. Determination of thermal stability of specific biomarker lipids of the freshwater fern Azolla through hydrous pyrolysis

    NASA Astrophysics Data System (ADS)

    Sap, Merel; Speelman, Eveline N.; Lewan, Michael D.; Sinninghe Damsté, Jaap S.; Reichart, Gert-Jan

    2010-05-01

    Enormous blooms of the free-floating freshwater fern Azolla occurred within the Arctic Basin during an extended period of ~1.2 Ma during the middle Eocene (Brinkhuis et al. 2006; Speelman et al., GB, 2009). The sustained growth of Azolla, currently ranking among the fastest growing plants on Earth, in a major anoxic basin may have substantially contributed to decreasing atmospheric CO2 levels by burial of Azolla-derived organic matter. Speelman et al. (OG, 2009) reported biomarkers for Azolla (1,w20 C32 - C36 diols, structurally related C29 ω20,ω21 diols, C29 1,20,21 triols, C29 dihydroxy fatty acids as well as a series of wax esters containing these mono- and dihydroxy lipids), which can be used to reconstruct palaeo-environmental conditions. Here we assess the thermal stability of these compounds, to extend their biomarker potential. We specifically focused on the thermal stability of the Azolla biomarkers using hydrous pyrolysis in order to determine which burial conditions allow reconstruction of past occurrences of Azolla. In addition, hydrous pyrolysis was also performed on samples from the Eocene Arctic Ocean (ACEX core), to test if and how the biomarkers change under higher temperatures and pressures in situ. During hydrous pyrolysis, the biomass was heated under high pressure at temperatures ranging between 220 and 365°C for 72 hours. Four experiments were also run using different durations to explore the kinetics of biomarker degradation at specific temperatures. First results indicate that the Azolla specific diols are still present at 220°C, while the corresponding wax esters are already absent. At 300°C all Azolla specific biomarkers are destroyed. More specific determination of the different biomarkers' stability and kinetics would potentially allow the reconstruction of the temperature and pressure history of Azolla deposits. Literature: • Brinkhuis, H., Schouten, S., Collinson, M. E., Sluijs, A., Sinninghe Damste, J. S., Dickens, G. R., Huber

  2. Fluorescence detection by intensity changes for high-performance thin-layer chromatography separation of lipids using automated multiple development.

    PubMed

    Cebolla, Vicente L; Jarne, Carmen; Domingo, Pilar; Domínguez, Andrés; Delgado-Camón, Aránzazu; Garriga, Rosa; Galbán, Javier; Membrado, Luis; Gálvez, Eva M; Cossío, Fernando P

    2011-05-13

    Changes in emission of berberine cation, induced by non-covalent interactions with lipids on silica gel plates, can be used for detecting and quantifying lipids using fluorescence scanning densitometry in HPTLC analysis. This procedure, referred to as fluorescence detection by intensity changes (FDIC) has been used here in combination with automated multiple development (HPTLC/AMD), a gradient-based separation HPTLC technique, for separating, detecting and quantifying lipids from different families. Three different HPTLC/AMD gradient schemes have been developed for separating: neutral lipid families and steryl glycosides; different sphingolipids; and sphingosine-sphinganine mixtures. Fluorescent molar responses of studied lipids, and differences in response among different lipid families have been rationalized in the light of a previously proposed model of FDIC response, which is based on ion-induced dipole interactions between the fluorophore and the analyte. Likewise, computational calculations using molecular mechanics have also been a complementary useful tool to explain high FDIC responses of cholesteryl and steryl-derivatives, and moderate responses of sphingolipids. An explanation for the high FDIC response of cholesterol, whose limit of detection (LOD) is 5 ng, has been proposed. Advantages and limitations of FDIC application have also been discussed. PMID:21145556

  3. Using fluorescence-activated flow cytometry to determine reactive oxygen species formation and membrane lipid peroxidation in viable boar spermatozoa.

    PubMed

    Guthrie, H David; Welch, Glenn R

    2010-01-01

    Fluorescence-activated flow cytometry analyses were developed for determination of reactive oxygen species (ROS) formation and membrane lipid peroxidation in live spermatozoa loaded with, respectively, hydroethidine (HE) or the lipophilic probe 4,4-difluoro-5-(4-phenyl-1,3-butadienyl)-4-bora-3a,4a-diaza-s-indacene-3-undecanoic acid, C(11)BODIPY(581/591) (BODIPY). ROS was detected by red fluorescence emission from oxidization of HE and membrane lipid peroxidation was detected by green fluorescence emission from oxidation of BODIPY in individual live sperm. Of the reactive oxygen species generators tested, BODIPY oxidation was specific for FeSo4/ascorbate (FeAc), because menadione and H(2)O(2) had little or no effect. The oxidization of hydroethidine to ethidium was specific for menadione and H(2)O(2); FeAc had no effect. The incidence of basal or spontaneous ROS formation and membrane lipid peroxidation were low in boar sperm (<1% of live sperm) in fresh semen or after low temperature storage; however the sperm were quite susceptible to treatment-induced ROS formation and membrane lipid peroxidation. PMID:20072917

  4. Postprandial lipid responses to standard carbohydrate challenges used to determine glycemic index values

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Prior studies assessing metabolic effects of different types of carbohydrate have focused on their glycemic response. Not considered has been the response of postprandial cardiometabolic risk indicators. This study assessed the postprandial lipid responses to two forms of carbohydrates used as ref...

  5. In vivo thickness dynamics measurement of tear film lipid and aqueous layers with optical coherence tomography and maximum-likelihood estimation.

    PubMed

    Huang, Jinxin; Hindman, Holly B; Rolland, Jannick P

    2016-05-01

    Dry eye disease (DED) is a common ophthalmic condition that is characterized by tear film instability and leads to ocular surface discomfort and visual disturbance. Advancements in the understanding and management of this condition have been limited by our ability to study the tear film secondary to its thin structure and dynamic nature. Here, we report a technique to simultaneously estimate the thickness of both the lipid and aqueous layers of the tear film in vivo using optical coherence tomography and maximum-likelihood estimation. After a blink, the lipid layer was rapidly thickened at an average rate of 10  nm/s over the first 2.5 s before stabilizing, whereas the aqueous layer continued thinning at an average rate of 0.29  μm/s of the 10 s blink cycle. Further development of this tear film imaging technique may allow for the elucidation of events that trigger tear film instability in DED. PMID:27128054

  6. Determinants for Achieving the LDL-C Target of Lipid Control for Secondary Prevention of Cardiovascular Events in Taiwan

    PubMed Central

    Ho, Li-Ting; Yin, Wei-Hsian; Chuang, Shao-Yuan; Tseng, Wei-Kung; Wu, Yen-Wen; Hsieh, I-Chang; Lin, Tsung-Hsien; Li, Yi-Heng; Huang, Lien-Chi; Wang, Kuo-Yang; Ueng, Kwo-Chang; Fang, Ching-Chang; Pan, Wen-Harn; Yeh, Hung-I; Wu, Chau-Chung; Chen, Jaw-Wen

    2015-01-01

    Background Epidemiological and clinical studies have clearly established the link between low-density lipoprotein cholesterol (LDL-C) and atherosclerosis-related cardiovascular consequences. Although it has been a common practice for physicians to prescribe lipid-lowering therapy for patients with dyslipidemia, the achievement rate is still not satisfied in Taiwan. Therefore, the determinants for achieving the LDL-C target needed to be clarified for better healthcare of the patients with dyslipidemia. Method This registry-type prospective observational study enrolled the patients with cardiovascular diseases (coronary artery disease (CAD) and cerebrovascular disease (CVD)) from 18 medical centers across Taiwan, and clinically followed them for five years. At every clinical visit, vital signs, clinical endpoints, adverse events, concurrent medications and laboratory specimens were obtained as thoroughly as possible. The lipid profile (total cholesterol, high-density lipoprotein cholesterol, LDL-C, triglyceride), liver enzymes, and creatinine phosphokinase were evaluated at baseline, and every year thereafter. The cross sectional observational data was analyzed for this report. Result Among the 3,486 registered patients, 54% had their LDL-C < 100 mg/dL. By univariate analysis, the patients achieving the LDL-C target were associated with older age, more male sex, taller height, lower blood pressure, more under lipid-lowering therapy, more smoking cessation, more history of CAD, DM, physical activity, but less history of CVD. The multivariate analysis showed statin therapy was the most significant independent determinant for achieving the treatment target, followed by age, history of CAD, diabetes, blood pressure, and sex. However, most patients were on regimens of very-low to low equipotent doses of statins. Conclusion Although the lipid treatment guideline adherence is improving in recent years, only 54% of the patients with cardiovascular diseases have achieved

  7. Comparison of Methods for Determining Boundary Layer Edge Conditions for Transition Correlations

    NASA Technical Reports Server (NTRS)

    Liechty, Derek S.; Berry, Scott A.; Hollis, Brian R.; Horvath, Thomas J.

    2003-01-01

    Data previously obtained for the X-33 in the NASA Langley Research Center 20-Inch Mach 6 Air Tunnel have been reanalyzed to compare methods for determining boundary layer edge conditions for use in transition correlations. The experimental results were previously obtained utilizing the phosphor thermography technique to monitor the status of the boundary layer downstream of discrete roughness elements via global heat transfer images of the X-33 windward surface. A boundary layer transition correlation was previously developed for this data set using boundary layer edge conditions calculated using an inviscid/integral boundary layer approach. An algorithm was written in the present study to extract boundary layer edge quantities from higher fidelity viscous computational fluid dynamic solutions to develop transition correlations that account for viscous effects on vehicles of arbitrary complexity. The boundary layer transition correlation developed for the X-33 from the viscous solutions are compared to the previous boundary layer transition correlations. It is shown that the boundary layer edge conditions calculated using an inviscid/integral boundary layer approach are significantly different than those extracted from viscous computational fluid dynamic solutions. The present results demonstrate the differences obtained in correlating transition data using different computational methods.

  8. Development and validation of TLC-densitometric method for determination of lipid A adjuvant as a bulk and in solid fat nanoemulsions.

    PubMed

    Minz, Sunita; Kaurav, Monika; Sahu, Kantrol Kumar; Mandal, Vivekananda; Pandey, Ravi Shankar

    2015-10-01

    A simple, sensitive, selective and precise high-performance thin-layer chromatographic method was developed for determination of lipid A (MPLA) adjuvant as a bulk and in solid fat nanoemulsions. Chromatographic separations were performed on thin-layer chromatography aluminum plates precoated with silica gel 60 F-254 as stationary phase and chloroform-methanol-ethyl acetate solution (10:2:4, v/v/v) as mobile phase. With this solvent system, compact spots for MPLA at Rf value 0.80 ± 0.02 were obtained. Densitometric analysis of MPLA was carried out in absorbance mode at 357 nm. Linear regression analysis for the calibration plots showed good linear relationship with r = 0.9996 in the concentration range of 20-100 ng/spot. The mean values (±SD) of slope and intercept were found to be 7.355 ± 0.006 and 109.52 ± 0.170, respectively. Limits of detection (LOD) and quantitation (LOQ) were observed at 3.096 and 9.382 ng/spot, respectively.The method was validated for precision, accuracy, robustness and recovery as per the International Conference on Harmonization guidelines. Statistical analysis proved that the developed method for quantification of MPLA as a bulk and in solid fat nanoemulsions is reproducible, selective and economical. This method could be applied for quantitative assay of MPLA in lipid-based vaccine formulations. PMID:25708181

  9. Formation of a suspended lipid membrane on a microcavity covered by a thin SiO2 layer with a nanohole array

    NASA Astrophysics Data System (ADS)

    Tanaka, Aya; Kashimura, Yoshiaki; Kuramochi, Eiichi; Sumitomo, Koji

    2014-01-01

    To provide a platform for a nanobiodevice, we fabricated microcavities on a Si/SiO2 substrate covered by a thin SiO2 layer with nanohole arrays that we call a pepper shaker substrate. Fluorescence and atomic force microscopy images showed that the structure of the pepper shaker substrate improved both the probability of membrane sealing over the microcavities by rupturing giant unilameller vesicles and the lifetime of the lipid membrane suspended over the microcavities. The success of this study reveals the potential for fabricating an artificial cell array as a tool for the functional and high throughput analysis of membrane proteins.

  10. Archaebacterial activity in the Orca Basin determined by the isolation of characteristic isopranyl ether-linked lipids

    NASA Astrophysics Data System (ADS)

    Dickins, Holli D.; Van Vleet, Edward S.

    1992-04-01

    Phytanyl glycerol ether lipids characteristic of archaebacterial inputs have been quantified in 30 water samples taken in the Orca Basin, an anoxic hypersaline basin located in the northwestern Gulf of Mexico. Because of the Basin's anoxic hypersaline character, it seems likely that archaebacteria may play a significant role in the microbial ecology of the brine. Physical data, including temperature, salinity, per cent transmission, oxygen and nutrient concentrations, also were collected from six depths at five sampling sites in the Basin. Four of the five sites were characterized by a 200 m thick, anoxic brine (salinity ≈ 250 ppt) at an approximate water depth of 2240 m. A stepwise increase in salinity was associated with the brine-seawater interface, increasing from 38 to 150 ppt within the upper portion of the 10 m interface and to >250 ppt within the brine. Three distinct layers of particulate material were observed within the 10 m interface. Corresponding with the salinity gradient was a decrease in dissolved oxygen from 5.0 ml l -1 at 2040 m to 0 ml l -1 within the brine. Ammonia and phosphate concentrations increased from 0 and 2.5 μM above the brine to 519 and 63.5 μM within the brine. At the same time, nitrate concentrations decreased from 22 μM above the brine to negligible within the brine. Depletion of oxygen, with concomitant increases in ammonia and phosphate, decreased nitrate, and the production of methane suggest microbially mediated processes may be occurring at the brine-seawater interface. Highest concentrations of phytanyl ether lipids were observed within the interface, ranging from 29.7 to 84.1 ng l -1. Concentrations were negligible below the interface. Elevated phytanyl ether lipid concentrations in conjunction with microbial activity studies carried out by other investigators suggest that archaebacterial activity is occurring within the brine particulate layers. A decline in ether lipid concentration and microbial activity below this

  11. Determination of lipid oxidation products in vegetable oils and marine omega-3 supplements

    PubMed Central

    Halvorsen, Bente Lise; Blomhoff, Rune

    2011-01-01

    Background There is convincing evidence that replacing dietary saturated fats with polyunsaturated fats (PUFA) decreases risk of cardiovascular diseases. Therefore, PUFA rich foods such as vegetable oils, fatty fish, and marine omega-3 supplements are recommended. However, PUFA are easily oxidizable and there is concern about possible negative health effects from intake of oxidized lipids. Little is known about the degree of lipid oxidation in such products. Objective To assess the content of lipid oxidation products in a large selection of vegetable oils and marine omega-3 supplements available in Norway. Both fresh and heated vegetable oils were studied. Design A large selection of commercially available vegetable oils and marine omega-3 supplements was purchased from grocery stores, pharmacies, and health food stores in Norway. The content of lipid oxidation products were measured as peroxide value and alkenal concentration. Twelve different vegetable oils were heated for a temperature (225°C) and time (25 minutes) resembling conditions typically used during cooking. Results The peroxide values were in the range 1.04–10.38 meq/kg for omega-3 supplements and in the range 0.60–5.33 meq/kg for fresh vegetable oils. The concentration range of alkenals was 158.23–932.19 nmol/mL for omega-3 supplements and 33.24–119.04 nmol/mL for vegetable oils. After heating, a 2.9–11.2 fold increase in alkenal concentration was observed for vegetable oils. Conclusions The contents of hydroperoxides and alkenals in omega-3 supplements are higher than in vegetable oils. After heating vegetable oils, a large increase in alkenal concentration was observed. PMID:21691461

  12. Determination of general relations for the behavior of turbulent boundary layers

    NASA Technical Reports Server (NTRS)

    Von Doenhoff, Albert E; Tetervin, Neal

    1943-01-01

    An analysis has been made of a considerable amount of data for turbulent boundary layers along wings and bodies of various shapes in order to determine the fundamental variables that control the development of turbulent boundary layers. It was found that the type of velocity distribution in the boundary layer could be expressed in terms of a single parameter. This parameter was chosen as the ratio of the displacement thickness to the momentum thickness of the boundary layer. The variables that control the development of the turbulent boundary layer apparently are: (1) the ratio of the nondimensional pressure gradient, expressed in terms of the local dynamic pressure outside the boundary layer and boundary-layer thickness, to the local skin-friction coefficient and (2) the shape of the boundary layer. An empirical equation has been developed in terms of these variables that, when used with the momentum equation and the skin-friction relation, makes it possible to trace the development of the turbulent boundary layer to the separation point.

  13. Lipid and fatty acid analysis of the Plodia interpunctella granulosis virus (PiGV) envelope

    NASA Technical Reports Server (NTRS)

    Shastri-Bhalla, K.; Funk, C. J.; Consigli, R. A.; Spooner, B. S. (Principal Investigator)

    1993-01-01

    Virus envelope was isolated from Plodia interpunctella granulosis virus, produced in early fourth-instar larvae. Both polar and neutral lipids were analyzed by two-dimensional thin-layer chromatography. Fatty acid composition of various individual neutral and polar lipids was determined by gas-liquid chromatography. The major components of envelope neutral lipid were diacylglycerols. Palmitic acid and stearic acid were the major saturated fatty acids in both polar and neutral lipids. Whereas palmitoleic acid was the major unsaturated fatty acids in neutral lipids, oleic acid was the major unsaturated fatty acid in the polar lipids.

  14. Study of the Use of Lipid Panels as a Marker of Insulin Resistance to Determine Cardiovascular Risk

    PubMed Central

    Bertsch, Ruth Ann; Merchant, Maqdooda A

    2015-01-01

    Context: When assessing the lipid panel, practical physicians tend to focus on the low-density lipoprotein cholesterol (LDL-c). However, an elevated triglyceride/high-density lipoprotein cholesterol (HDL-c) ratio, suggesting insulin resistance, also effectively predicts cardiovascular outcomes but requires different treatments than an elevated LDL-c. We tested whether high triglyceride/HDL-c ratios are associated with more risk than high LDL-c concentrations or other lipid markers of atherogenicity. Methods: We followed 103,646 members aged 50 to 75 years without cardiovascular disease or diabetes in a community health plan. Subjects were categorized as insulin sensitive or insulin resistant on the basis of triglyceride and HDL-c in the index year. The primary outcome was ischemic heart disease. The percentage of subjects with a primary outcome after 8 years was stratified by insulin category, lipid measures, and blood pressure. Hazard ratios (HR) for insulin resistance, LDL-c, age, sex, and the presence of hypertension were determined in a multivariate analysis. Results: Subjects with insulin resistance but lipid measures healthier than the median had worse outcomes than those who were insulin sensitive but had unhealthier lipid measures such as non-HDL-c and the ratios of total cholesterol/HDL-c and LDL-c/HDL-c. The HR for a 60 mg/dL increase in LDL-c was 1.14 (95% confidence interval [CI], 1.10–1.18); the HR for an LDL-c greater than 160 mg/dL was 1.19 (95% CI, 1.12–1.28). In contrast, the hazard ratio for having an insulin-resistant triglyceride/HDL-c ratio was 1.68 (95% CI, 1.57–1.80), compared with an insulin-sensitive ratio. There was no difference in outcomes between insulin-resistant but normotensive patients and insulin-sensitive but hypertensive patients. Conclusion: Insulin resistance, as manifested by a high triglyceride/HDL-c ratio, was associated with adverse cardiovascular outcomes more than other lipid metrics, including LDL-c, which had

  15. Determination of the stacking order of curved few-layered graphene systems

    NASA Astrophysics Data System (ADS)

    Hayashi, Takuya; MuramatsuCurrent Affiliation: Department Of Materials Science; Technology, Nagaoka University Of Technology, 1603-1, Kamitomioka, Nagaoka, 940-2188, Japan, Hiroyuki; ShimamotoCurrent Affiliation: Advanced Manufacturing Research Institute, Aist, 2266-98 Anagahora, Shimoshidami, Moriyama-Ku, Nagoya 463-8560, Japan, Daisuke; Fujisawa, Kazunori; Tojo, Tomohiro; Muramoto, Yoshitaka; Yokomae, Takuya; Asaoka, Toru; Kim, Yoong Ahm; Terrones, Mauricio; Endo, Morinobu

    2012-09-01

    We report a facile method to efficiently visualize the atomic carbon network of curved few-layered graphitic systems including folded bi-layer graphene, nanoribbon edges and multi-walled carbon nanotubes (straight and bent), via the processing of aberration-corrected high-resolution transmission electron microscopy (AC-HRTEM) images. This technique is also able to atomically resolve the structure of overlapping graphene layers with different orientations, thus enabling us to determine the stacking order of multiple graphene layers. To the best of our knowledge, we are the first to identify the stacking order of a misoriented 4-layer closed-edge graphene and a metal-semiconductor double-walled carbon nanotube junction.

  16. A simple method to determine evaporation duct height in the sea surface boundary layer

    NASA Astrophysics Data System (ADS)

    Musson-Genon, Luc; Gauthier, Sylvie; Bruth, Eric

    1992-09-01

    A formulation to determine the evaporation duct height in the sea surface boundary layer is presented. This formulation is based upon the theory of similarity of Monin Obukhov by using analytical solutions currently used in the field of numerical weather prediction. The proposed solution is simple, coherent with the surface boundary layer parameterization used in the Meteo France and European Centre for Medium-Range Weather Forecasts weather prediction models and gives good results when compared to more traditional methods.

  17. Identification of block copolymers and determination of their purity by thin-layer chromatography.

    PubMed

    Gankina, E S; Efimova, I I; Kever, J J; Belenkii, B G

    1987-01-01

    The application of adsorption, precipitation and extraction thin-layer chromatography to the identification of block copolymers, determination of their homogeneity (mixtures of homopolymers), and evaluation of their compositional homogeneity by one- and two-dimensional, multistage and gradient methods, is described. To detect the polymers on the thin-layer plate, various methods of detection are used, including those specific for each component of the block copolymer. Examples of analysis of the following block copolymers by thin-layer chromatography are reported: PS-PMMA, PS-PB, PS-PAN, PS-PBG, PI-PMS-PI, PMMA-PBMA, PMMA-PBG, PS-PEO. PMID:18964274

  18. Salt-bridge-supported bilayer lipid membrane biosensor for determination of anticancer drug cyclophosphamide

    NASA Astrophysics Data System (ADS)

    Zhang, Yanli; Wang, Tao; Zhang, Chunxu; Shen, Hanxi; Chao, Fuhuan

    2001-09-01

    A novel biosensor for assaying anticancer drug cyclophosphamide was constructed with salt-bridge supported bilayer lipid membrane modified with tetraphenylborate- cyclophosphamide complex. The modification was achieved by the introduction of the complex into the membrane forming solution. The biosensor show a linear response to the drug over the concentration range 8.96 X 10-6 mol L-1. The effects of coexistent substances and pH on assay were evaluated. The results show that the distinguish merits of this kind of biosensor is the excellently biological compatibility and no need of mediator for ions exchange. It also shows good selectivity and sensitivity for cyclophosphamide assay.

  19. X-Ray Structure Determination of Fully Hydrated L_alpha Phase DPPC Lipid Bilayers

    NASA Astrophysics Data System (ADS)

    Nagle, John F.

    1996-03-01

    Accurate and reliable structural information is more difficult to obtain for lipid bilayers in the biologically relevant fully hydrated L_α thermodynamic phase than for bilayers at lower hydration or for phases that occur at lower temperature because there are fewer x-ray or neutron reflections. There have been many studies of the benchmark lipid DPPC, but these have yielded unacceptably large discrepancies ranging from 58 to 71 Åfor interfacial area A^F per lipid molecule. We have resolved this uncertainty using X-ray scattering with high instrumental resolution at CHESS for multilamellar vesicles of L_α phase lipid bilayers of DPPC at 50^circC under varying osmotic pressure.(This work was performed by the authors of ref. 3 and Horia Petrache. This research is supported by NIH grant GM-44976.) Artifacts in the magnitudes of the form factors due to liquid crystalline fluctuations have been eliminated by using modified Caillé theory (R. Zhang, R. M. Suter and J. F. Nagle, Phys. Rev. E50, 5047 (1994)), which we have shown to provide an excellent fit to the data (R. Zhang, S. Tristram-Nagle, W. Sun, R. Headrick, T. Irving, R. Suter and J. Nagle, Biophys. J., in press for 1/96). The Caillé fluctuation parameter η1 increases systematically with increasing D spacing and this explains why some higher order peaks are unobservable for the larger D spacings. The corrected form factors fall on one smooth continuous transform F(q); this shows that the bilayer does not change shape as D decreases from 67.2 Åfully hydrated) to 53.9 Åthereby validating the biological relevance of older neutron diffraction data taken on less than fully hydrated samples. We obtain the distance between headgroup peaks from Fourier reconstruction of electron density profiles for samples with four orders of diffraction and also from electron density models that use 38 independent form factors. By combining these results with our previous gel phase results, we obtain the area A^F = 62.9±1.3

  20. Lipids of Sarcina lutea III. Composition of the Complex Lipids

    PubMed Central

    Huston, Charles K.; Albro, Phillip W.; Grindey, Gerald B.

    1965-01-01

    Huston, Charles K. (Fort Detrick, Frederick, Md.), Phillip W. Albro, and Gerald B. Grindey. Lipids of Sarcina lutea. III. Composition of the complex lipids. J. Bacteriol. 89:768–775. 1965.—The complex lipids from a strain of Sarcina lutea were isolated and separated into fractions on diethylaminoethyl cellulose acetate and silicic acid columns. These fractions were monitored in several thin-layer chromatography systems. The various lipid types were characterized by their behavior in thin-layer systems and by an analysis of their hydrolysis products. The fatty acid composition of the column fractions was determined by gas-liquid chromatography. A number of components (13) were separated by thin-layer chromatography and characterized. The major components were polyglycerol phosphatide (17.0%), lipoamino acids (15.1%), phosphatidyl glycerol (13.8%), and an incompletely characterized substance (15.0%). Minor constituents included phosphatidyl inositol (5.5%), phosphatidic acid (4.2%), phosphatidyl serine (2.0%), and phosphatidyl choline (1.0%). No phosphatidyl ethanolamine was observed. PMID:14273659

  1. Experimental determination and computational interpretation of biophysical properties of lipid bilayers enriched by cholesteryl hemisuccinate.

    PubMed

    Kulig, Waldemar; Jurkiewicz, Piotr; Olżyńska, Agnieszka; Tynkkynen, Joona; Javanainen, Matti; Manna, Moutusi; Rog, Tomasz; Hof, Martin; Vattulainen, Ilpo; Jungwirth, Pavel

    2015-02-01

    Cholesteryl hemisuccinate (CHS) is one of the cholesterol-mimicking detergents not observed in nature. It is, however, widely used in protein crystallography, in biochemical studies of proteins, and in pharmacology. Here, we performed an extensive experimental and theoretical study on the behavior of CHS in lipid membranes rich in unsaturated phospholipids. We found that the deprotonated form of CHS (that is the predominant form under physiological conditions) does not mimic cholesterol very well. The protonated form of CHS does better in this regard, but also its ability to mimic the physical effects of cholesterol on lipid membranes is limited. Overall, although ordering and condensing effects characteristic to cholesterol are present in systems containing any form of CHS, their strength is appreciably weaker compared to cholesterol. Based on the considerable amount of experimental and atomistic simulation data, we conclude that these differences originate from the fact that the ester group of CHS does not anchor it in an optimal position at the water-membrane interface. The implications of these findings for considerations of protein-cholesterol interactions are briefly discussed. PMID:25450348

  2. Effect of Dietary Marine Microalgae (Schizochytrium) Powder on Egg Production, Blood Lipid Profiles, Egg Quality, and Fatty Acid Composition of Egg Yolk in Layers

    PubMed Central

    Park, J. H.; Upadhaya, S. D.; Kim, I. H.

    2015-01-01

    Two hundred and sixteen Institut de Sélection Animale (ISA) brown layers (40 wks of age) were studied for 6 wks to examine the effect of microalgae powder (MAP) on egg production, egg quality, blood lipid profile, and fatty acid concentration of egg yolk. Dietary treatments were as follows: i) CON (basal diet), ii) 0.5% MAP (CON+0.5% Schizochytrium powder), and iii) 1.0% MAP (CON+1.0% Schizochytrium powder). From 44 to 46 wks, egg production was higher in 1.0% MAP treatment than in control treatment (linear, p = 0.034); however, there was no difference on the egg production from 40 to 43 wks (p>0.05). Serum triglyceride and total cholesterol were significantly reduced in the groups fed with MAP, compared to those in groups fed with control diets (Quadratic, p = 0.034 and p = 0.039, respectively). Inclusion of 0.5% MAP in the diet of layers improved egg yolk color, compared with hens fed with basal diet at 46 wks (quadratic, p = 0.044). Eggshell thickness was linearly increased in MAP-fed treatments at 46th wk (p<0.05). Concentration of yolk docosahexaenoic acid (DHA; C22:6n-3) was increased in treatment groups fed with MAP (linear, p<0.05). The n-6 fatty acids, n-6/n-3 fatty acid, and unsaturated fatty acid/saturated fatty acid were decreased in treatment groups fed with MAP (linear, p<0.05). These results suggest that MAP improved the egg production and egg quality, and may affect serum lipid metabolites in the layers. In addition, MAP increases yolk DHA levels, and deceases n-6/n-3 fatty acid ratio. PMID:25656210

  3. Determination of the Mixing Layer Height Over two Sites, Using Pilot Balloons During the MILAGRO Campaign

    NASA Astrophysics Data System (ADS)

    Wohrnschimmel, H.; Alonso, A. L.; Ángeles, F.; Sosa, G.; Varela, J.; Cárdenas, B.

    2007-12-01

    Among the mechanisms that affect air quality there is a variety of meteorological processes. An important process in this context are the changes in the mixing layer height during a day and over the year. The mixing layer height is the portion of the atmosphere close to the surface layer where air pollutants get diluted, without leaving this layer. Therefore, it is important to describe the variations in the height of the mixing layer, i.e. the vertical dilution of air pollution, since this is a process mitigating naturally the impact of emissions. There exist different methods to obtain information on the mixing layer height, among them radio soundings, the application of vertical wind profilers, and launching pilot balloons. In this study, pilot balloons have been used simultaneously over two sites of the Mexico City Metropolitan Area during the MILAGRO campaign in March 2006. The objective was to determine the vertical wind profiles and derive information on the mixing layer height. Daily, four pilot balloons were launched, at 9:00, 12:00, 15:00, and 18:00 hours, over Tenango del Aire (a rural area in the Southeast of Mexico City), and over Ciudad Universitaria, in the Southern metropolitan area. At some occasions, night time measurements have been carried out at 21:00 and 24:00. A variability of the diurnal evolution of the mixing layer was observed along March, which could be related to surface temperature. The diurnal evolution showed a sudden growth of the mixing layer between 9:00 and 12:00 hours. Data intercomparisons were carried out for pilot balloons versus radio soundings during a few days at a third site, Tula, in the North of Mexico City. Both intercomparisons showed that pilot balloons are an effective method to obtain information about the development of the mixing layer.

  4. The role of lipid profile in determining the risk of ischemic stroke in the elderly: a case-control study.

    PubMed

    Denti, Licia; Cecchetti, Alessandra; Annoni, Valentina; Merli, Maria Francesca; Ablondi, Fabrizio; Valenti, Giorgio

    2003-01-01

    In this study, we investigated the association of lipids with ischemic stroke and its different subtypes in elderly patients. In particular, lipid parameters not extensively investigated so far in previous case-control studies specifically focused in the old population, such as lipoprotein Lp (a) and Apoproteins AI (ApoAI) and B (ApoB), have been taken into account. Seventy nine patients (mean age 83 +/- 7.4, range 67-99), consecutively admitted to a Geriatric Ward between January 1998 and June 2000 with acute stroke (first event) were studied. A complete clinical and laboratory assessment, including neurological evaluation, head CT scan, carotid ultrasonography and ECG, was employed to define the clinical and etiologic stroke subtype, according to standardized criteria. Fasting blood samples were collected within 48 h from admission, for determination of total cholesterol (TC), triglycerides (TG), High Density Lipoprotein-cholesterol (HDL-C), Lp(a), ApoAI and ApoB; Low Density Lipoprotein-Cholesterol (LDL-C) was estimated by Friedwald formula. Eighty eight age and sex-matched outpatients, referred to the hospital for non-inflammatory disorders of joints and musculoskeletal system, served as controls. Patients showed HDL-C and HDL-C/ApoAI ratio significantly lower than controls, with higher LDL-C/HDL-C ratio. Analysis on quartiles of lipoprotein concentrations showed also a significant increase in odds of stroke for LDL-C concentrations over 100 mg/dl, in absence of a linear relationship between LDL-C levels and risk. Multiple logistic regression, adjusting for non-lipid risk factors for stroke, confirmed the independent association of low HDL-C and HDL-C/ApoAI with all strokes, as well as with each subtype. In conclusion, these data suggest that lipids give some contribution to stroke risk even in the elderly, with a more prevalent role for HDL than LDL, and that lipid profile assessment must be taken into account in estimating the individual risk of stroke. PMID

  5. Permuting the PGF Signature Motif Blocks both Archaeosortase-Dependent C-Terminal Cleavage and Prenyl Lipid Attachment for the Haloferax volcanii S-Layer Glycoprotein

    PubMed Central

    Abdul Halim, Mohd Farid; Karch, Kelly R.; Zhou, Yitian; Haft, Daniel H.; Garcia, Benjamin A.

    2015-01-01

    ABSTRACT For years, the S-layer glycoprotein (SLG), the sole component of many archaeal cell walls, was thought to be anchored to the cell surface by a C-terminal transmembrane segment. Recently, however, we demonstrated that the Haloferax volcanii SLG C terminus is removed by an archaeosortase (ArtA), a novel peptidase. SLG, which was previously shown to be lipid modified, contains a C-terminal tripartite structure, including a highly conserved proline-glycine-phenylalanine (PGF) motif. Here, we demonstrate that ArtA does not process an SLG variant where the PGF motif is replaced with a PFG motif (slgG796F,F797G). Furthermore, using radiolabeling, we show that SLG lipid modification requires the PGF motif and is ArtA dependent, lending confirmation to the use of a novel C-terminal lipid-mediated protein-anchoring mechanism by prokaryotes. Similar to the case for the ΔartA strain, the growth, cellular morphology, and cell wall of the slgG796F,F797G strain, in which modifications of additional H. volcanii ArtA substrates should not be altered, are adversely affected, demonstrating the importance of these posttranslational SLG modifications. Our data suggest that ArtA is either directly or indirectly involved in a novel proteolysis-coupled, covalent lipid-mediated anchoring mechanism. Given that archaeosortase homologs are encoded by a broad range of prokaryotes, it is likely that this anchoring mechanism is widely conserved. IMPORTANCE Prokaryotic proteins bound to cell surfaces through intercalation, covalent attachment, or protein-protein interactions play critical roles in essential cellular processes. Unfortunately, the molecular mechanisms that anchor proteins to archaeal cell surfaces remain poorly characterized. Here, using the archaeon H. volcanii as a model system, we report the first in vivo studies of a novel protein-anchoring pathway involving lipid modification of a peptidase-processed C terminus. Our findings not only yield important insights into

  6. Back-calculation of temperature parameters for determination of asphalt layer modulus

    NASA Astrophysics Data System (ADS)

    Dong, Qinxi; Matsui, Kunihito; Yamamoto, Kazuya; Higashi, Shigeo

    2000-05-01

    The pavement elastic modulus of each layer was usually assumed not to be dependent on the environmental factors when the backcalculation of asphalt pavement was conducted from the measured surface deflections of FWD. However, it is well known that the elastic modulus of asphalt layer changes with the variation of temperature. Considering the influence of atmospheric temperature and radiant heat, the temperature distribution is nonlinear along the asphalt layer thickness, and has always been changed. Therefore, the distribution of elastic modulus in the asphalt layer has been considered to change as well. In this paper, we assume the elastic modulus distribution of the asphalt layer to vary with its temperature in terms of the exponential form. Based on the finite element method forward analysis, we propose a method to estimate a standard elastic modulus and temperature coefficient at 20 degrees Celsius for the asphalt layer from the backcalculation analysis. The corresponding FEM backcalculation program using Gauss-Newton method was developed to determine the pavement layer moduli and temperature dependent coefficient, in which the singular value decomposition (SVD) was used for the inverse analysis with scaling of unknown parameters. This method results in a smaller condition number that contributes to improvement of numerical stability. Both numerical simulation and measured data from FWD testing are used to demonstrate the potential applications of this method. As a result, the backcalculation procedure is less dependent on the user's initial values, fast in convergence rate and effective in the pavement engineering.

  7. Quantification of brain lipids by FTIR spectroscopy and partial least squares regression

    NASA Astrophysics Data System (ADS)

    Dreissig, Isabell; Machill, Susanne; Salzer, Reiner; Krafft, Christoph

    2009-01-01

    Brain tissue is characterized by high lipid content. Its content decreases and the lipid composition changes during transformation from normal brain tissue to tumors. Therefore, the analysis of brain lipids might complement the existing diagnostic tools to determine the tumor type and tumor grade. Objective of this work is to extract lipids from gray matter and white matter of porcine brain tissue, record infrared (IR) spectra of these extracts and develop a quantification model for the main lipids based on partial least squares (PLS) regression. IR spectra of the pure lipids cholesterol, cholesterol ester, phosphatidic acid, phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol, sphingomyelin, galactocerebroside and sulfatide were used as references. Two lipid mixtures were prepared for training and validation of the quantification model. The composition of lipid extracts that were predicted by the PLS regression of IR spectra was compared with lipid quantification by thin layer chromatography.

  8. A Biochemical GC-MS Application for the Organic Chemistry Laboratory: Determination of Fatty Acid Composition of Arabidopsis thaliana Lipids

    NASA Astrophysics Data System (ADS)

    Bender, Jared D.; Catino, Arthur J., III.; Hess, Kenneth R.; Lassman, Michael E.; Leber, Phyllis A.; Reinard, Michael D.; Strotman, Neil A.; Pike, Carl S.

    2000-11-01

    A biochemical application of GC-MS in which students determine the qualitative and quantitative lipid composition of plant leaf samples is described. There are four facets of this project: (i) synthesis and characterization of individual fatty acid methyl esters (FAMEs) as standards for GC-MS analysis, (ii) isolation of the fatty acids of Arabidopsis thaliana leaves, both wild type and mutants, as FAMEs, (iii) GC-MS analysis of the Arabidopsis leaf extracts for fatty acid composition, and (iv) comparison of the class results with the literature data for both wild type and the four mutants and with a biochemical model of two pathways for lipid synthesis in Arabidopsis leaves. Because this experimental paradigm links organic synthesis and spectral characterization by IR and NMR, both 1H and 13C, with separation and identification via GC-MS analysis, all of the key areas of laboratory procedure are encompassed in this single project. The experimental design permits a myriad of hypothesis-testing variations. Plants can be grown at different temperatures and for different lengths of time to determine if and how fatty acid composition varies. Different types of plant leaves can be examined to ascertain if each has a unique fatty acid fingerprint.

  9. Free-energy determinants of alpha-helix insertion into lipid bilayers.

    PubMed Central

    Ben-Tal, N; Ben-Shaul, A; Nicholls, A; Honig, B

    1996-01-01

    A detailed treatment is provided of the various free-energy terms that contribute to the transfer of a polyalanine alpha-helix from the aqueous phase into lipid bilayers. In agreement with previous work, the hydrophobic effect is found to provide the major driving force for helix insertion. However, an opposing effect of comparable magnitude is also identified and is attributed to the large free-energy penalty associated with the desolvation of peptide hydrogen bonds on transfer to the low dielectric environment of the bilayer. Lipid perturbation effects as well as the entropy loss associated with helix immobilization in the bilayer are also evaluated. Two configurations of a membrane-bound 25mer polyalanine helix were found to be lower in free energy than the isolated helix in the aqueous phase. The first corresponds to the case of vertical insertion, in which a helix terminus protrudes from each side of the bilayer. The second minimum is for the case of horizontal insertion, for which the helix is adsorbed upon the surface of the bilayer. The calculated free-energy minima are found to be in good agreement with recent measurements of related systems. Large free-energy barriers resulting from desolvation of unsatisfied hydrogen-bonding groups at the helix termini are obtained for both insertion processes. The barriers for insertion are significantly reduced if the helix termini are assumed to be "capped" through the formation of hydrogen bonds with polar sidechains. For uncapped helices, our results support recently proposed models in which helices are inserted by first adsorbing on the membrane surface and then having one terminus "swing around" so as to penetrate the bilayer. Images FIGURE 1 PMID:8785340

  10. Determining the Optical Properties of Two-Layer Turbid Materials Based on Spatially Resolved Diffuse Reflectance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hyperspectral imaging-based spatially resolved technique is useful for determining the optical properties of fruits and food products that are homogeneous. To better characterize fruit properties and quality attributes, it is necessary to consider fruit to be composed of two homogeneous layers, i.e....

  11. Experimental phasing for structure determination using membrane-protein crystals grown by the lipid cubic phase method

    SciTech Connect

    Li, Dianfan; Pye, Valerie E.; Caffrey, Martin

    2015-01-01

    Very little information is available in the literature concerning the experimental heavy-atom phasing of membrane-protein structures where the crystals have been grown using the lipid cubic phase (in meso) method. In this paper, pre-labelling, co-crystallization, soaking, site-specific mercury binding to genetically engineered single-cysteine mutants and selenomethionine labelling as applied to an integral membrane kinase crystallized in meso are described. An assay to assess cysteine accessibility for mercury labelling of membrane proteins is introduced. Despite the marked increase in the number of membrane-protein structures solved using crystals grown by the lipid cubic phase or in meso method, only ten have been determined by SAD/MAD. This is likely to be a consequence of the technical difficulties associated with handling proteins and crystals in the sticky and viscous hosting mesophase that is usually incubated in glass sandwich plates for the purposes of crystallization. Here, a four-year campaign aimed at phasing the in meso structure of the integral membrane diacylglycerol kinase (DgkA) from Escherichia coli is reported. Heavy-atom labelling of this small hydrophobic enzyme was attempted by pre-labelling, co-crystallization, soaking, site-specific mercury binding to genetically engineered single-cysteine mutants and selenomethionine incorporation. Strategies and techniques for special handling are reported, as well as the typical results and the lessons learned for each of these approaches. In addition, an assay to assess the accessibility of cysteine residues in membrane proteins for mercury labelling is introduced. The various techniques and strategies described will provide a valuable reference for future experimental phasing of membrane proteins where crystals are grown by the lipid cubic phase method.

  12. Parametric studies to determine the effect of compliant layers on metal matrix composite systems

    NASA Technical Reports Server (NTRS)

    Caruso, J. J.; Chamis, C. C.; Brown, H. C.

    1990-01-01

    Computational simulation studies are conducted to identify compliant layers to reduce matrix stresses which result from the coefficient of thermal expansion mismatch and the large temperature range over which the current metal matrix composites will be used. The present study includes variations of compliant layers and their properties to determine their influence on unidirectional composite and constituent response. Two simulation methods are used for these studies. The first approach is based on a three-dimensional linear finite element analysis of a 9 fiber unidirectional composite system. The second approach is a micromechanics based nonlinear computer code developed to determine the behavior of metal matrix composite system for thermal and mechanical loads. The results show that an effective compliant layer for the SCS 6 (SiC)/Ti-24Al-11Nb (Ti3Al + Nb) and SCS 6 (SiC)/Ti-15V-3Cr-3Sn-3Al (Ti-15-3) composite systems should have modulus 15 percent that of the matrix and a coefficient of thermal expansion of the compliant layer roughly equal to that of the composite system without the CL. The matrix stress in the longitudinal and the transverse tangent (loop) direction are tensile for the Ti3Al + Nb and Ti-15-3 composite systems upon cool down from fabrication. The fiber longitudinal stress is compressive from fabrication cool down. Addition of a recommended compliant layer will result in a reduction in the composite modulus.

  13. Lipid hydroperoxide determination in dark chicken meat through a ferrous oxidation-xylenol orange method.

    PubMed

    Grau, A; Codony, R; Rafecas, M; Barroeta, A C; Guardiola, F

    2000-09-01

    A ferrous oxidation-xylenol orange (FOX) method was adapted to measure lipid hydroperoxides (LHP) in raw and cooked dark chicken meat. Its applicability was evaluated using samples with different alpha-tocopherol contents or unsaturation degrees (both modulated by dietary supplementation). The FOX assay can work as an induced method because there is some oxidation of the sample extract during the incubation of the reaction. Consequently, it allows assessment of sample susceptibility to oxidation (response after some hours of incubation) and comparison of samples that are highly oxidized or readily susceptible to oxidation through their absorbance after 30 min of incubation. It is highly specific for LHP and showed a linear relationship between volume of meat extract and absorbance. However, the most suitable volume of extract and incubation time must be studied for each kind of sample. The use of butylated hydroxytoluene during this incubation is strongly discouraged because it attenuated the reaction by radical stabilization, thus diminishing Fe(III) formation and leading to a lower response. PMID:10995327

  14. Lipid droplets hypertrophy: a crucial determining factor in insulin regulation by adipocytes

    NASA Astrophysics Data System (ADS)

    Sanjabi, Bahram; Dashty, Monireh; Özcan, Behiye; Akbarkhanzadeh, Vishtaseb; Rahimi, Mehran; Vinciguerra, Manlio; van Rooij, Felix; Al-Lahham, Saad; Sheedfar, Fareeba; van Kooten, Theo G.; Spek, C. Arnold; Rowshani, Ajda T.; van der Want, Johannes; Klaassen, Rene; Sijbrands, Eric; Peppelenbosch, Maikel P.; Rezaee, Farhad

    2015-03-01

    Lipid droplets (LDs) hypertrophy in adipocytes is the main cause of energy metabolic system dysfunction, obesity and its afflictions such as T2D. However, the role of adipocytes in linking energy metabolic disorders with insulin regulation is unknown in humans. Human adipocytes constitutively synthesize and secrete insulin, which is biologically functional. Insulin concentrations and release are fat mass- and LDs-dependent respectively. Fat reduction mediated by bariatric surgery repairs obesity-associated T2D. The expression of genes, like PCSK1 (proinsulin conversion enzyme), GCG (Glucagon), GPLD1, CD38 and NNAT, involved in insulin regulation/release were differentially expressed in pancreas and adipose tissue (AT). INS (insulin) and GCG expression reduced in human AT-T2D as compared to AT-control, but remained unchanged in pancreas in either state. Insulin levels (mRNA/protein) were higher in AT derived from prediabetes BB rats with destructed pancreatic β-cells and controls than pancreas derived from the same rats respectively. Insulin expression in 10 human primary cell types including adipocytes and macrophages is an evidence for extrapancreatic insulin-producing cells. The data suggest a crosstalk between AT and pancreas to fine-tune energy metabolic system or may minimize the metabolic damage during diabetes. This study opens new avenues towards T2D therapy with a great impact on public health.

  15. Biochemical determination of lipid content in hepatic steatosis by the Soxtec method

    PubMed Central

    Hijona, Elizabeth; Hijona, Lander; Larzabal, Mikel; Sarasqueta, Cristina; Aldazabal, Pablo; Arenas, Juan; Bujanda, Luis

    2010-01-01

    AIM: To establish a quantitative method to measure the amount of lipids. METHODS: The livers of 53 male Wistar rats (225 g) with different degrees of hepatic steatosis were studied. This model of hepatic steatosis was based on a high carbohydrate, fat-free modified diet. Biopsies were classified into four grades depending on fat accumulation, using the Kleiner and Brunt classification. Total fat was studied by the Soxtec method (Soxtec™ 2050 Auto Fat Extraction System), and agreement between both assays was assessed by calculating the κ coefficient. RESULTS: According to the histological classification, 38% of rats presented grade 0, 21% grade 1, 22% grade 2 and 20% grade 3. The amount of fat per 100 g tissue was 2.60 ± 0.64 g for grade 0, 3.87 ± 1.59 g for grade 1, 5.82 ± 1.37 g for grade 2 and 8.68 ± 2.30 g for grade 3. Statistically significant differences were found between the mean values for each of the histological grades (P < 0.05). The correlation for the quantification of fat in the liver between both assays was moderate (κ = 0.60). CONCLUSION: The biochemical quantification of fat in liver tissue by the Soxtec method was correlated with the histological classification, although the agreement between the two tests was only moderate. PMID:20333790

  16. Determination of Lipid-Protein Interactions in Lung Surfactants Using Computer Simulations and Structural Bioinformatics.

    NASA Astrophysics Data System (ADS)

    Kaznessis, Yiannis

    2001-06-01

    Proteins are the primary components of the networks that conduct the flows of mass, energy and information in living organisms. The discovery of the principles of protein structure and function allows the development of design rules for biological activities. The microscopic nature of the operating mechanisms of protein activity, and the vast complexity of the networks of interaction call for the employment of powerful computational methodologies that can decipher the physicochemical and evolutionary principles underlying protein structure and function. An example will be presented that reflects the strength of computational approaches. Atomistic molecular dynamics simulations and structural bioinformatics tools are employed to investigate the interactions between the first 25 N-terminal residues of surfactant protein B (SP-B 1-25) and the lipid components of the lung surfactant (LS). An understanding of the molecular level interactions between the LS components is essential for the establishment of design rules for the development of synthetic LS and the treatment of the neonatal respiratory distress syndrome, which results from deficiency or inactivation of LS.

  17. Determining the Effect of Growth Rate on Hydrogen Isotope Fractionation of Algal Lipids in Two North Pacific Sites

    NASA Astrophysics Data System (ADS)

    Wolfshorndl, M.; Sachs, J. P.

    2015-12-01

    Tropical hydrologic changes have a large effect on global climate, but there does not yet exist a good indicator of rainfall variation in the tropics. Understanding past natural variability of such features as the Intertropical Convergence Zone and El Niño Southern Oscillation provides information about the extent of anthropogenic climate change today. The hydrogen isotopic composition (D/H ratio) of algal lipids has been shown to track the isotopic composition of source water in which the organism grew, providing information about precipitation variability over time. However, culture work has revealed that environmental factors such as salinity, temperature, growth rate, and irradiance also influence algal lipid D/H ratios. Here I present work determining the effect of growth rate and irradiance on the hydrogen isotope composition of alkenone-producing algae in the water column in two North Pacific locations, off the coast of Oregon and near the Hawaii Ocean Time Series site. This work corroborates empirical relationships observed in culture studies and indicates that the effects of growth rate and irradiance should be taken into account when applying the D/H isotope ratio rainfall proxy to reconstruct past climates.

  18. Experimental phasing for structure determination using membrane-protein crystals grown by the lipid cubic phase method

    PubMed Central

    Li, Dianfan; Pye, Valerie E.; Caffrey, Martin

    2015-01-01

    Despite the marked increase in the number of membrane-protein structures solved using crystals grown by the lipid cubic phase or in meso method, only ten have been determined by SAD/MAD. This is likely to be a consequence of the technical difficulties associated with handling proteins and crystals in the sticky and viscous hosting mesophase that is usually incubated in glass sandwich plates for the purposes of crystallization. Here, a four-year campaign aimed at phasing the in meso structure of the integral membrane diacylglycerol kinase (DgkA) from Escherichia coli is reported. Heavy-atom labelling of this small hydrophobic enzyme was attempted by pre-labelling, co-crystallization, soaking, site-specific mercury binding to genetically engineered single-cysteine mutants and selenomethionine incorporation. Strategies and techniques for special handling are reported, as well as the typical results and the lessons learned for each of these approaches. In addition, an assay to assess the accessibility of cysteine residues in membrane proteins for mercury labelling is introduced. The various techniques and strategies described will provide a valuable reference for future experimental phasing of membrane proteins where crystals are grown by the lipid cubic phase method. PMID:25615865

  19. Parenteral lipid fatty acid composition directly determines the fatty acid composition of red blood cell and brain lipids in preterm pigs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Studies in enterally-fed infants have shown a positive effect of n-3 long-chain polyunsaturated fatty acid (LCPUFA) supplementatin on neurodevelopment. The effect of n-3 LCPUFA in fish oil-based parenteral (PN) lipid emulsions on neuronal tissues of PN-fed preterm infants is unknown. The objective ...

  20. Oceanic upper mixed layer depth determination by the use of satellite data

    NASA Technical Reports Server (NTRS)

    Yan, Xiao-Hai; Schubel, J. R.; Pritchard, D. W.

    1990-01-01

    A method has been developed to determine the oceanic daily mean mixed layer depth from satellite observations and a mixed layer thermal inertia (MLTI) model. The algorithms were developed to use remotely-sensed values of sea surface temperature, albedo, and surface wind speeds to calculate the thermal inertia and to predict changes in subsurface diurnal mixed layer depth. The MLTI model, based on a mixed layer model of the upper ocean, has been used to simulate the diurnal mixing process and thermal inertia distribution in the Sargasso Sea around 34 deg N, 70 deg W. Sea surface temperature and albedo have been obtained from the NOAA7-AVHRR images. Surface wind speeds have been derived from the Scanning Multichannel Microwave Radiometer (SMMR) aboard Nimbus 7. Image processing was performed for images gathered between June and July 1982. The daily mean mixed layer depths predicted by the MLTI model agree well with data gathered at the LOTUS mooring located in the Sargasso Sea. This suggests that vertical mixing is the dominant physical process that controls the thermal inertia distribution in the midocean, far from major current systems, and that remote sensing is a promising tool to study such upper ocean processes.

  1. Ionic Hydrogen Bonds and Lipid Packing Defects Determine the Binding Orientation and Insertion Depth of RecA on Multicomponent Lipid Bilayers.

    PubMed

    Zhang, Leili; Rajendram, Manohary; Weibel, Douglas B; Yethiraj, Arun; Cui, Qiang

    2016-08-25

    We describe a computational and experimental approach for probing the binding properties of the RecA protein at the surface of anionic membranes. Fluorescence measurements indicate that RecA behaves differently when bound to phosphatidylglycerol (PG)- and cardiolipin (CL)-containing liposomes. We use a multistage computational protocol that integrates an implicit membrane/solvent model, the highly mobile mimetic membrane model, and the full atomistic membrane model to study how different anionic lipids perturb RecA binding to the membrane. With anionic lipids studied here, the binding interface involves three key regions: the N-terminal helix, the DNA binding loop L2, and the M-M7 region. The nature of binding involves both electrostatic interactions between cationic protein residues and lipid polar/charged groups and insertion of hydrophobic residues. The L2 loop contributes more to membrane insertion than the N-terminal helix. More subtle aspects of RecA-membrane interaction are influenced by specific properties of anionic lipids. Ionic hydrogen bonds between the carboxylate group in phosphatidylserine and several lysine residues in the C-terminal region of RecA stabilize the parallel (∥) binding orientation, which is not locally stable on PG- and CL-containing membranes despite similarity in the overall charge density. Lipid packing defects, which are more prevalent in the presence of conical lipids, are observed to enhance the insertion depth of hydrophobic motifs. The computational finding that RecA binds in a similar orientation to PG- and CL-containing membranes is consistent with the fact that PG alone is sufficient to induce RecA polar localization, although CL might be more effective because of its tighter binding to RecA. The different fluorescence behaviors of RecA upon binding to PG- and CL-containing liposomes is likely due to the different structures and flexibility of the C-terminal region of RecA when it binds to different anionic phospholipids

  2. On determining characteristic length scales in pressure gradient turbulent boundary layers

    NASA Astrophysics Data System (ADS)

    Vinuesa, Ricardo; Örlü, Ramis; Schlatter, Philipp

    2016-04-01

    In the present work we analyze three methods used to determine the edge of pressure gradient turbulent boundary layers: two based on composite profiles, the one by Chauhan et al. (Fluid Dyn. Res. 41:021401, 2009) and the one by Nickels (J. Fluid Mech. 521:217–239, 2004), and the other one based on the condition of vanishing mean velocity gradient. Additionally, a new method is introduced based on the diagnostic plot concept by Alfredsson et al. (Phys. Fluids 23:041702, 2011). The boundary layer developing over the suction side of a NACA4412 wing profile, extracted from a direct numerical simulation at Rec = 400,000, is used as the test case. We find that all the methods produce robust results with mild or moderate pressure gradients, but stronger pressure gradients (with β larger than around 7) lead to inconsistent results in all the techniques except the diagnostic plot. This method also has the advantage of providing an objective way of defining the point where the mean streamwise velocity is 99% of the edge velocity, and shows consistent results in a wide range of pressure gradient conditions, as well as flow histories. Therefore, the technique based on the diagnostic plot is a robust method to determine the boundary layer thickness (equivalent to δ99) and edge velocity in pressure gradient turbulent boundary layers.

  3. Strength of integration of transmembrane alpha-helical peptides in lipid bilayers as determined by atomic force spectroscopy.

    PubMed

    Ganchev, Dragomir N; Rijkers, Dirk T S; Snel, Margot M E; Killian, J Antoinette; de Kruijff, Ben

    2004-11-30

    In this study we address the stability of integration of proteins in membranes. Using dynamic atomic force spectroscopy, we measured the strength of incorporation of peptides in lipid bilayers. The peptides model the transmembrane parts of alpha-helical proteins and were studied in both ordered peptide-rich and unordered peptide-poor bilayers. Using gold-coated AFM tips and thiolated peptides, we were able to observe force events which are related to the removal of single peptide molecules out of the bilayer. The data demonstrate that the peptides are very stably integrated into the bilayer and that single barriers within the investigated region of loading rates resist their removal. The distance between the ground state and the barrier for peptide removal was found to be 0.75 +/- 0.15 nm in different systems. This distance falls within the thickness of the interfacial layer of the bilayer. We conclude that the bilayer interface region plays an important role in stably anchoring transmembrane proteins into membranes. PMID:15554706

  4. Novel therapeutic mechanisms determine the effectiveness of lipid-core nanocapsules on melanoma models.

    PubMed

    Drewes, Carine C; Fiel, Luana A; Bexiga, Celina G; Asbahr, Ana Carolina C; Uchiyama, Mayara K; Cogliati, Bruno; Araki, Koiti; Guterres, Sílvia S; Pohlmann, Adriana R; Farsky, Sandra P

    2016-01-01

    Melanoma is a severe metastatic skin cancer with poor prognosis and no effective treatment. Therefore, novel therapeutic approaches using nanotechnology have been proposed to improve therapeutic effectiveness. Lipid-core nanocapsules (LNCs), prepared with poly(ε-caprolactone), capric/caprylic triglyceride, and sorbitan monostearate and stabilized by polysorbate 80, are efficient as drug delivery systems. Here, we investigated the effects of acetyleugenol-loaded LNC (AcE-LNC) on human SK-Mel-28 melanoma cells and its therapeutic efficacies on melanoma induced by B16F10 in C57B6 mice. LNC and AcE-LNC had z-average diameters and zeta potential close to 210 nm and -10.0 mV, respectively. CytoViva(®) microscopy images showed that LNC and AcE-LNC penetrated into SK-Mel-28 cells, and remained in the cytoplasm. AcE-LNC in vitro treatment (18-90×10(9) particles/mL; 1 hour) induced late apoptosis and necrosis; LNC and AcE-LNC (3-18×10(9) particles/mL; 48 hours) treatments reduced cell proliferation and delayed the cell cycle. Elevated levels of nitric oxide were found in supernatant of LNC and AcE-LNC, which were not dependent on nitric oxide synthase expressions. Daily intraperitoneal or oral treatment (days 3-10 after tumor injection) with LNC or AcE-LNC (1×10(12) particles/day), but not with AcE (50 mg/kg/day, same dose as AcE-LNC), reduced the volume of the tumor; nevertheless, intraperitoneal treatment caused toxicity. Oral LNC treatment was more efficient than AcE-LNC treatment. Moreover, oral treatment with nonencapsulated capric/caprylic triglyceride did not inhibit tumor development, implying that nanocapsule supramolecular structure is important to the therapeutic effects. Together, data herein presented highlight the relevance of the supramolecular structure of LNCs to toxicity on SK-Mel-28 cells and to the therapeutic efficacy on melanoma development in mice, conferring novel therapeutic mechanisms to LNC further than a drug delivery system. PMID:27099491

  5. Novel therapeutic mechanisms determine the effectiveness of lipid-core nanocapsules on melanoma models

    PubMed Central

    Drewes, Carine C; Fiel, Luana A; Bexiga, Celina G; Asbahr, Ana Carolina C; Uchiyama, Mayara K; Cogliati, Bruno; Araki, Koiti; Guterres, Sílvia S; Pohlmann, Adriana R; Farsky, Sandra P

    2016-01-01

    Melanoma is a severe metastatic skin cancer with poor prognosis and no effective treatment. Therefore, novel therapeutic approaches using nanotechnology have been proposed to improve therapeutic effectiveness. Lipid-core nanocapsules (LNCs), prepared with poly(ε-caprolactone), capric/caprylic triglyceride, and sorbitan monostearate and stabilized by polysorbate 80, are efficient as drug delivery systems. Here, we investigated the effects of acetyleugenol-loaded LNC (AcE-LNC) on human SK-Mel-28 melanoma cells and its therapeutic efficacies on melanoma induced by B16F10 in C57B6 mice. LNC and AcE-LNC had z-average diameters and zeta potential close to 210 nm and -10.0 mV, respectively. CytoViva® microscopy images showed that LNC and AcE-LNC penetrated into SK-Mel-28 cells, and remained in the cytoplasm. AcE-LNC in vitro treatment (18–90×109 particles/mL; 1 hour) induced late apoptosis and necrosis; LNC and AcE-LNC (3–18×109 particles/mL; 48 hours) treatments reduced cell proliferation and delayed the cell cycle. Elevated levels of nitric oxide were found in supernatant of LNC and AcE-LNC, which were not dependent on nitric oxide synthase expressions. Daily intraperitoneal or oral treatment (days 3–10 after tumor injection) with LNC or AcE-LNC (1×1012 particles/day), but not with AcE (50 mg/kg/day, same dose as AcE-LNC), reduced the volume of the tumor; nevertheless, intraperitoneal treatment caused toxicity. Oral LNC treatment was more efficient than AcE-LNC treatment. Moreover, oral treatment with nonencapsulated capric/caprylic triglyceride did not inhibit tumor development, implying that nanocapsule supramolecular structure is important to the therapeutic effects. Together, data herein presented highlight the relevance of the supramolecular structure of LNCs to toxicity on SK-Mel-28 cells and to the therapeutic efficacy on melanoma development in mice, conferring novel therapeutic mechanisms to LNC further than a drug delivery system. PMID:27099491

  6. Spatial coherence effect on layer thickness determination in narrowband full-field optical coherence tomography

    SciTech Connect

    Safrani, Avner; Abdulhalim, Ibrahim

    2011-06-20

    Longitudinal spatial coherence (LSC) is determined by the spatial frequency content of an optical beam. The use of lenses with a high numerical aperture (NA) in full-field optical coherence tomography and a narrowband light source makes the LSC length much shorter than the temporal coherence length, hence suggesting that high-resolution 3D images of biological and multilayered samples can be obtained based on the low LSC. A simplified model is derived, supported by experimental results, which describes the expected interference output signal of multilayered samples when high-NA lenses are used together with a narrowband light source. An expression for the correction factor for the layer thickness determination is found valid for high-NA objectives. Additionally, the method was applied to a strongly scattering layer, demonstrating the potential of this method for high-resolution imaging of scattering media.

  7. Determining the number of hidden units in multi-layer perceptrons using F-ratios

    NASA Technical Reports Server (NTRS)

    Jansen, Ben H.; Desai, Pratish R.

    1993-01-01

    The hidden units in multi-layer perceptrons are believed to act as feature extractors. In other words, the outputs of the hidden units represent the features in a more traditional statistical classification paradigm. This viewpoint offers a statistical, objective approach to determining the optimal number of hidden units required. This approach is based on an F-ratio test, and proceeds in an iterative fashion. The method and its application to simulated time-series data are presented.

  8. Computer model of unstirred layer and intracellular pH changes. Determinants of unstirred layer pH.

    PubMed

    Marrannes, Roger

    2013-06-01

    Transmembrane acid-base fluxes affect the intracellular pH and unstirred layer pH around a superfused biological preparation. In this paper the factors influencing the unstirred layer pH and its gradient are studied. An analytical expression of the unstirred layer pH gradient in steady state is derived as a function of simultaneous transmembrane fluxes of (weak) acids and bases with the dehydration reaction of carbonic acid in equilibrium. Also a multicompartment computer model is described consisting of the extracellular bulk compartment, different unstirred layer compartments and the intracellular compartment. With this model also transient changes and the influence of carbonic anhydrase (CA) can be studied. The analytical expression and simulations with the multicompartment model demonstrate that in steady state the unstirred layer pH and its gradient are influenced by the size and type of transmembrane flux of acids and bases, their dissociation constant and diffusion coefficient, the concentration, diffusion coefficient and type of mobile buffers and the activity and location of CA. Similar principles contribute to the amplitude of the unstirred layer pH transients. According to these models an immobile buffer does not influence the steady-state pH, but reduces the amplitude of pH transients especially when these are fast. The unstirred layer pH provides useful information about transmembrane acid-base fluxes. This paper gives more insight how the unstirred layer pH and its transients can be interpreted. Methodological issues are discussed. PMID:23860924

  9. Determination of the Schottky barrier height of ferromagnetic contacts to few-layer phosphorene

    SciTech Connect

    Anugrah, Yoska; Robbins, Matthew C.; Koester, Steven J.; Crowell, Paul A.

    2015-03-09

    Phosphorene, the 2D analogue of black phosphorus, is a promising material for studying spin transport due to its low spin-orbit coupling and its ½ nuclear spin, which could allow the study of hyperfine effects. In this work, the properties of permalloy (Py) and cobalt (Co) contacts to few-layer phosphorene are presented. The Schottky barrier height was extracted and determined as a function of gate bias. Flat-band barrier heights, relative to the valence band edge, of 110 meV and 200 meV were determined for Py and Co, respectively. These results are important for future studies of spin transport in phosphorene.

  10. Note: Non-invasive optical method for rapid determination of alignment degree of oriented nanofibrous layers

    NASA Astrophysics Data System (ADS)

    Pokorny, M.; Klemes, J.; Rebicek, J.; Kotzianova, A.; Velebny, V.

    2015-10-01

    This paper presents a rapid non-destructive method that provides information on the anisotropic internal structure of nanofibrous layers. A laser beam of a wavelength of 632.8 nm is directed at and passes through a nanofibrous layer prepared by electrostatic spinning. Information about the structural arrangement of nanofibers in the layer is directly visible in the form of a diffraction image formed on a projection screen or obtained from measured intensities of the laser beam passing through the sample which are determined by the dependency of the angle of the main direction of polarization of the laser beam on the axis of alignment of nanofibers in the sample. Both optical methods were verified on Polyvinyl alcohol (PVA) nanofibrous layers (fiber diameter of 470 nm) with random, single-axis aligned and crossed structures. The obtained results match the results of commonly used methods which apply the analysis of electron microscope images. The presented simple method not only allows samples to be analysed much more rapidly and without damaging them but it also makes possible the analysis of much larger areas, up to several square millimetres, at the same time.

  11. Note: Non-invasive optical method for rapid determination of alignment degree of oriented nanofibrous layers

    SciTech Connect

    Pokorny, M.; Rebicek, J.; Klemes, J.; Kotzianova, A.; Velebny, V.

    2015-10-15

    This paper presents a rapid non-destructive method that provides information on the anisotropic internal structure of nanofibrous layers. A laser beam of a wavelength of 632.8 nm is directed at and passes through a nanofibrous layer prepared by electrostatic spinning. Information about the structural arrangement of nanofibers in the layer is directly visible in the form of a diffraction image formed on a projection screen or obtained from measured intensities of the laser beam passing through the sample which are determined by the dependency of the angle of the main direction of polarization of the laser beam on the axis of alignment of nanofibers in the sample. Both optical methods were verified on Polyvinyl alcohol (PVA) nanofibrous layers (fiber diameter of 470 nm) with random, single-axis aligned and crossed structures. The obtained results match the results of commonly used methods which apply the analysis of electron microscope images. The presented simple method not only allows samples to be analysed much more rapidly and without damaging them but it also makes possible the analysis of much larger areas, up to several square millimetres, at the same time.

  12. Note: Non-invasive optical method for rapid determination of alignment degree of oriented nanofibrous layers.

    PubMed

    Pokorny, M; Klemes, J; Rebicek, J; Kotzianova, A; Velebny, V

    2015-10-01

    This paper presents a rapid non-destructive method that provides information on the anisotropic internal structure of nanofibrous layers. A laser beam of a wavelength of 632.8 nm is directed at and passes through a nanofibrous layer prepared by electrostatic spinning. Information about the structural arrangement of nanofibers in the layer is directly visible in the form of a diffraction image formed on a projection screen or obtained from measured intensities of the laser beam passing through the sample which are determined by the dependency of the angle of the main direction of polarization of the laser beam on the axis of alignment of nanofibers in the sample. Both optical methods were verified on Polyvinyl alcohol (PVA) nanofibrous layers (fiber diameter of 470 nm) with random, single-axis aligned and crossed structures. The obtained results match the results of commonly used methods which apply the analysis of electron microscope images. The presented simple method not only allows samples to be analysed much more rapidly and without damaging them but it also makes possible the analysis of much larger areas, up to several square millimetres, at the same time. PMID:26521008

  13. Determination of lipid and phenolic fraction in two hazelnut (Corylus avellana L.) cultivars grown in Poland.

    PubMed

    Ciemniewska-Żytkiewicz, Hanna; Verardo, Vito; Pasini, Federica; Bryś, Joanna; Koczoń, Piotr; Caboni, Maria Fiorenza

    2015-02-01

    The fatty acid, tocopherol, sterol, phospholipid and phenolic compositions of Polish hazelnuts (Kataloński and Webba Cenny) were examined. Particularly, free+esterified and bound tocopherol, sterol and phenolic compounds were determined. The major fatty acids found in hazelnuts were oleic and linoleic acids. α-Tocopherol was the most abundant tocopherol accounting for 90-92% of the total content. Bound tocopherols represented 45.5% and 21.7% of total tocopherols in Kataloński and Webba Cenny cultivar, respectively. Total free+esterified sterols were between 62.0% and 75.7% of total sterols and β-sitosterol was the first sterol in the two samples. Phosphatidylcholine was the most common phospholipid, accounting for 72.2% for Kataloński and 67.5% Webba Cenny, respectively. The most abundant fatty acids in the phospholipid fraction were oleic equally with palmitic acids. Twelve free and six bound phenolic compounds were identified and quantified in hazelnut kernel, instead nine free and six bound phenolic compounds were determined in hard shell. PMID:25172755

  14. Determination of band offsets at GaN/single-layer MoS2 heterojunction

    NASA Astrophysics Data System (ADS)

    Tangi, Malleswararao; Mishra, Pawan; Ng, Tien Khee; Hedhili, Mohamed Nejib; Janjua, Bilal; Alias, Mohd Sharizal; Anjum, Dalaver H.; Tseng, Chien-Chih; Shi, Yumeng; Joyce, Hannah J.; Li, Lain-Jong; Ooi, Boon S.

    2016-07-01

    We report the band alignment parameters of the GaN/single-layer (SL) MoS2 heterostructure where the GaN thin layer is grown by molecular beam epitaxy on CVD deposited SL-MoS2/c-sapphire. We confirm that the MoS2 is an SL by measuring the separation and position of room temperature micro-Raman E12g and A1g modes, absorbance, and micro-photoluminescence bandgap studies. This is in good agreement with HRTEM cross-sectional analysis. The determination of band offset parameters at the GaN/SL-MoS2 heterojunction is carried out by high-resolution X-ray photoelectron spectroscopy accompanying with electronic bandgap values of SL-MoS2 and GaN. The valence band and conduction band offset values are, respectively, measured to be 1.86 ± 0.08 and 0.56 ± 0.1 eV with type II band alignment. The determination of these unprecedented band offset parameters opens up a way to integrate 3D group III nitride materials with 2D transition metal dichalcogenide layers for designing and modeling of their heterojunction based electronic and photonic devices.

  15. Density of states determination in organic donor-acceptor blend layers enabled by molecular doping

    NASA Astrophysics Data System (ADS)

    Fischer, Janine; Ray, Debdutta; Kleemann, Hans; Pahner, Paul; Schwarze, Martin; Koerner, Christian; Vandewal, Koen; Leo, Karl

    2015-06-01

    Charge carrier transport is a key parameter determining the efficiency of organic solar cells, and is closely related to the density of free and trapped states. For trap characterization, impedance spectroscopy is a suitable, non-invasive method, applicable to complete organic semiconductor devices. In order to contribute to the capacitive signal, the traps must be filled with charge carriers. Typically, trap filling is achieved by illuminating the device or by injecting charge carriers through application of a forward bias voltage. However, in both cases, the exact number of charge carriers in the device is not known and depends strongly on the measurement conditions. Here, hole trap states of the model blend layer ZnPc:C60 are filled by weak p-doping, enabling trap characterization in a blend layer at a controlled hole density. We evaluate impedance spectra at different temperatures in order to determine the density of occupied states (DOOS) directly from the capacitance-frequency spectra by assuming a simple energy diagram. The reconstructed DOOS distribution is analyzed at different doping concentrations and device thicknesses and compared to thermally stimulated current measurements performed on the same devices. In both methods, a pronounced Gaussian peak at about 0.4 eV below the transport level is found as well as deep, exponential tail states, providing a deeper insight into the density of states distribution of this donor-acceptor blend layer. Additionally, the effect of doping-induced trap filling on the solar cell characteristics is studied in these devices.

  16. Determination of the parameters of a linear-viscoelastic thin layer using the normally-incident ultrasonic waves

    NASA Astrophysics Data System (ADS)

    Yao, Gui-Jin; Lü, Wei-Guo; Song, Ruo-Long; Cui, Zhi-Wen; Zhang, Xiang-Lin; Wang, Ke-Xie

    2010-07-01

    This paper proposes a method of simultaneous determination of the four layer parameters (mass density, longitudinal velocity, the thickness and attenuation) of an immersed linear-viscoelastic thin layer by using the normally-incident reflected and transmitted ultrasonic waves. The analytical formula of the layer thickness related to the measured transmitted transfer functions is derived. The two determination steps of the four layer parameters are developed, in which acoustic impedance, time-of-flight and attenuation are first determined by the reflected transfer functions. Using the derived formula, it successively calculates and determines the layer thickness, longitudinal velocity and mass density by the measured transmitted transfer functions. According to the two determination steps, a more feasible and simplified measurement setups is described. It is found that only three signals (the reference waves, the reflected and transmitted waves) need to be recorded in the whole measurement for the determination of the four layer parameters. A study of the stability of the determination method against the experimental noises and the error analysis of the four layer parameters are made. This study lays the theoretical foundation of the practical measurement of a linear-viscoelastic thin layer.

  17. Simultaneous determination of water-soluble vitamins by over-pressure layer chromatography and photodensitometric detection.

    PubMed

    Postaire, E; Cisse, M; Le Hoang, M D; Pradeau, D

    1991-04-01

    An over-pressure layer chromatographic procedure with photodensitometric detection for the simultaneous determination of water-soluble vitamins in multivitamin pharmaceutical preparations was developed and evaluated. The method uses high-performance TLC (HPTLC) plates with silica gel as the thin-layer, and an n-butanol:pyridine:water mixture (50:35:15, v/v/v) as mobile phase at a rate of 0.25 mL/min for baseline separation. The quantitation was carried out without derivatization (vitamin B1, vitamin B2, vitamin B6, folic acid, nicotinamide, vitamin C) or after spraying ninhydrin reagent (calcium pantothenate) or 4-dimethylaminocinnamaldehyde (vitamin B12, biotin). This was applied to the analysis of multivitamin solutions. Satisfactory relative standard deviations and good recovery were obtained for all the vitamins examined. It was concluded that this method is fast, accurate, specific, and suitable for routine quality control use. PMID:1865338

  18. The role of a small-scale cutoff in determining molecular layers at fluid interfaces.

    PubMed

    Sega, Marcello

    2016-08-17

    The existence of molecular layers at liquid/vapour interfaces has been a long debated issue. More than ten years ago it was shown, using computer simulations, that correlations at the liquid/vapour interface resemble those of bulk liquids, even though they can be detected in experiments only in a few cases, where they are so strong that they cannot be concealed by the geometrical smearing of capillary fluctuations. The results of the intrinsic analysis techniques used in computer experiments, however, are still often questioned because of their dependence on a free parameter that usually represents a small-scale cutoff used to determine the interface. In this work I show that there is only one value of the cutoff that can ensure a quantitative explanation of the intrinsic density correlation peaks in terms of successive layer contributions. The value of the cutoff coincides, with a high accuracy, with the molecular diameter. PMID:27499039

  19. Determination of Total Lipids as Fatty Acid Methyl Esters (FAME) by in situ Transesterification: Laboratory Analytical Procedure (LAP)

    SciTech Connect

    Van Wychen, S.; Laurens, L. M. L.

    2013-12-01

    This procedure is based on a whole biomass transesterification of lipids to fatty acid methyl esters to represent an accurate reflection of the potential of microalgal biofuels. Lipids are present in many forms and play various roles within an algal cell, from cell membrane phospholipids to energy stored as triacylglycerols.

  20. On determining characteristic length scales in pressure-gradient turbulent boundary layers

    NASA Astrophysics Data System (ADS)

    Vinuesa, R.; Bobke, A.; Örlü, R.; Schlatter, P.

    2016-05-01

    In the present work, we analyze three commonly used methods to determine the edge of pressure gradient turbulent boundary layers: two based on composite profiles, the one by Chauhan et al. ["Criteria for assessing experiments in zero pressure gradient boundary layers," Fluid Dyn. Res. 41, 021404 (2009)] and the one by Nickels ["Inner scaling for wall-bounded flows subject to large pressure gradients," J. Fluid Mech. 521, 217-239 (2004)], and the other one based on the condition of vanishing mean velocity gradient. Additionally, a new method is introduced based on the diagnostic plot concept by Alfredsson et al. ["A new scaling for the streamwise turbulence intensity in wall-bounded turbulent flows and what it tells us about the `outer' peak," Phys. Fluids 23, 041702 (2011)]. The boundary layers developing over the suction and pressure sides of a NACA4412 wing section, extracted from a direct numerical simulation at chord Reynolds number Rec = 400 000, are used as the test case, besides other numerical and experimental data from favorable, zero, and adverse pressure-gradient flat-plate turbulent boundary layers. We find that all the methods produce robust results with mild or moderate pressure gradients, although the composite-profile techniques require data preparation, including initial estimations of fitting parameters and data truncation. Stronger pressure gradients (with a Rotta-Clauser pressure-gradient parameter β larger than around 7) lead to inconsistent results in all the techniques except the diagnostic plot. This method also has the advantage of providing an objective way of defining the point where the mean streamwise velocity is 99% of the edge velocity and shows consistent results in a wide range of pressure gradient conditions, as well as flow histories. Collapse of intermittency factors obtained from a wide range of pressure-gradient and Re conditions on the wing further highlights the robustness of the diagnostic plot method to determine the

  1. Determination of band alignment in the single-layer MoS2/WSe2 heterojunction

    PubMed Central

    Chiu, Ming-Hui; Zhang, Chendong; Shiu, Hung-Wei; Chuu, Chih-Piao; Chen, Chang-Hsiao; Chang, Chih-Yuan S.; Chen, Chia-Hao; Chou, Mei-Yin; Shih, Chih-Kang; Li, Lain-Jong

    2015-01-01

    The emergence of two-dimensional electronic materials has stimulated proposals of novel electronic and photonic devices based on the heterostructures of transition metal dichalcogenides. Here we report the determination of band offsets in the heterostructures of transition metal dichalcogenides by using microbeam X-ray photoelectron spectroscopy and scanning tunnelling microscopy/spectroscopy. We determine a type-II alignment between MoS2 and WSe2 with a valence band offset value of 0.83 eV and a conduction band offset of 0.76 eV. First-principles calculations show that in this heterostructure with dissimilar chalcogen atoms, the electronic structures of WSe2 and MoS2 are well retained in their respective layers due to a weak interlayer coupling. Moreover, a valence band offset of 0.94 eV is obtained from density functional theory, consistent with the experimental determination. PMID:26179885

  2. Lipid nutritional value of legumes: Evaluation of different extraction methods and determination of fatty acid composition.

    PubMed

    Caprioli, Giovanni; Giusti, Federica; Ballini, Roberto; Sagratini, Gianni; Vila-Donat, Pilar; Vittori, Sauro; Fiorini, Dennis

    2016-02-01

    This study sought to contribute to the assessment of the nutritional properties of legumes by determining the fatty acid (FA) composition of 29 legume samples after the evaluation of nine extraction methods. The Folch method and liquid-solid extraction with hexane/isopropanol or with hexane/acetone were investigated, as was the effect of previous hydration of samples. Soxhlet extractions were also evaluated with different solvent mixtures. Results on FA composition using the hexane/isopropanol extraction method were the same in terms of FA composition of the Folch method, but the extraction yield was only around 20-40% of that of the Folch method preceded by hydration. Some types of legumes showed particularly interesting values for the ratio of polyunsaturated fatty acids (PUFAs) n-6/n-3, such as lentils, with the value of 4.0, and Azuki beans, at 3.2. In lentils, the PUFAs% ranged from 42.0% to 57.4%, while in Azuki beans it was 57.5%. PMID:26304436

  3. To determine ice layer thickness of Europa by high energy neutrino

    NASA Astrophysics Data System (ADS)

    Shoji, D.; Kurita, K.; Tanaka, H. K.

    2010-12-01

    Europa, the second closest Galilean satellite is one of the targets which are suspected to have an internal ocean. Detection and characterization of the internal ocean is one of the main subjects for Europa orbiter exploration. Although the gravitational data has shown the thickness of the surface H2O layer of 80-170km[1], it can not determine the phase of H2O. The variations in the magnetic field associated with the induced current in the internal ocean can determine the thickness of the layer of ice if satellite's orbits satisfy the required conditions. Observations of tidal amplitude forced by Jupiter can also resolve the thickness of the surface lithosphere[2]. At moment because of the lack of observational constraints there exist two contrasting models:thick ice layer model and thin model. Here we propose new method to detect the ocean directly based on the radiation by high energy neutrino interacted with matter. Schaefer et al[3] have proposed a similar method to determine ice layer thickness. We will focus on the detection of internal ocean for Europa and present the method is suitable for actual situations of Europa exploration by numerical simulations. Neutrino is famous for its traveling at long distance without any interaction with matter. When high energy neutrinos traverse in Europa hadronic showers are produced by the weak interaction with the nucleons that makes the body of Europa. These hadronic showers induces excess electrons. Because of these excess electrons, Cherenkov photons are emitted. When this radiation occurs in the ice layer, radiations whose wave length is over 10cm should be coherent because the scale of the shower becomes small (a few cm) in the ice, which is called as Askaryan effect[3]. Thus, the intensity of the radiation whose frequency is a few GHz should be enhanced. Since ice has a much longer attenuation length than water, the radiations which occur in the surface ice layer could be detected by the antenna outside Europa but

  4. Dual-Layered Nanogel-Coated Hollow Lipid/Polypeptide Conjugate Assemblies for Potential pH-Triggered Intracellular Drug Release

    PubMed Central

    Chiang, Wen-Hsuan; Huang, Wen-Chia; Shen, Ming-Yin; Wang, Che-Hsu; Huang, Yi-Fong; Lin, Sung-Chyr; Chern, Chorng-Shyan; Chiu, Hsin-Cheng

    2014-01-01

    To achieve effective intracellular anticancer drug delivery, the polymeric vesicles supplemented with the pH-responsive outlayered gels as a delivery system of doxorubicin (DOX) were developed from self-assembly of the lipid/polypeptide adduct, distearin grafted poly(γ-glutamic acid) (poly(γ-GA)), followed by sequential deposition of chitosan and poly(γ-GA-co-γ-glutamyl oxysuccinimide)-g-monomethoxy poly(ethylene glycol) in combination with in situ covalent cross-linking on assembly surfaces. The resultant gel-caged polymeric vesicles (GCPVs) showed superior performance in regulating drug release in response to the external pH change. Under typical physiological conditions (pH 7.4 and 37°C) at which the γ-GA/DOX ionic pairings remained mostly undisturbed, the dense outlayered gels of GCPVs significantly reduced the premature leakage of the uncomplexed payload. With the environmental pH being reduced from pH 7.4 to 4.7, the drug liberation was appreciably promoted by the massive disruption of the ionic γ-GA/DOX complexes along with the significant swelling of nanogel layers upon the increased protonation of chitosan chain segments. After being internalized by HeLa cells via endocytosis, GCPVs exhibited cytotoxic effect comparable to free DOX achieved by rapidly releasing the payload in intracellular acidic endosomes and lysosomes. This strongly implies the great promise of such unique GCPVs as an intracellular drug delivery carrier for potential anticancer treatment. PMID:24651156

  5. Determination by spaceborne backscatter lidar of the structural parameters of atmospheric scattering layers.

    PubMed

    Chazette, P; Pelon, J; Mégie, G

    2001-07-20

    Spaceborne active lidar systems are under development to give new insight into the vertical distribution of clouds and aerosols in the atmosphere and to provide new information on variables required for improvement of forecast models and for understanding the radiative and dynamic processes that are linked to the dynamics of climate change. However, when they are operated from space, lidar systems are limited by atmospheric backscattered signals that have low signal-to-noise ratios (SNRs) on optically thin targets. Therefore specific methods of analysis have to be developed to ensure accurate determination of the geometric and optical properties of scattering layers in the atmosphere. A first approach to retrieving the geometric properties of semitransparent cloud and aerosol layers is presented as a function of false-alarm and no-detection probabilities for a given SNR. Simulations show that the geometric properties of thin cirrus clouds and the altitude of the top of the unstable atmospheric boundary layer can be retrieved with standard deviations smaller than 150 m for a vertical resolution of the lidar system in the 50-100-m range and a SNR of 3. The altitudes of the top of dense clouds are retrieved with a precision in altitude of better than 50 m, as this retrieval corresponds to a higher SNR value. Such methods have an important potential application to future spaceborne lidar missions. PMID:18360368

  6. Reconstitution baking tests with defatted wheat flour are suitable for determining the functional effects of lipase-treated wheat lipids.

    PubMed

    Schaffarczyk, Monika; Østdal, Henrik; Matheis, Olivia; Jekle, Mario; Koehler, Peter

    2016-06-01

    A microscale reconstitution baking test, using wheat flour defatted with 2-propanol at 20 °C, was established to determine the functional effects of lipids isolated from lipase-treated wheat dough. Proper selection of solvent and extraction temperature was of major importance to maintain the functionality of defatted flour. Dough and gluten from flour defatted with water-saturated 1-butanol (WSB; extracted at 20 °C) and 2-propanol (extracted at 75 °C) had inferior extensibility and loaf volume compared to control flour extracted with 2-propanol at 20 °C. Quantitation of gluten proteins showed that defatting with WSB (20 °C) or 2-propanol (75 °C) decreased the gliadin and increased the glutenin content. Possible reasons were thiol-disulfide interchange reactions, caused either by heat (2-propanol, 75 °C) or by the solvent WSB, which affected gluten proteins. Confocal laser scanning microscopy showed that regular, interconnected gluten structures were only present in dough from flour defatted with 2-propanol at 20 °C. PMID:26830576

  7. Investigation of smart inspection of critical layer reticles using additional designer data to determine defect significance

    NASA Astrophysics Data System (ADS)

    Volk, William W.; Hess, Carl; Ruch, Wayne; Yu, Zongchang; Ma, Weimin; Fisher, Lisa; Vickery, Carl; Ma, Z. Mark

    2003-12-01

    With expected implementation of low k1 lithography on 193nm scanners for 65nm node wafer production, high resolution defect inspection will be needed to insure reticle quality and reticle manufacture process monitoring. Reticle cost and reticle defectivity are both increasing with each shrink to the next node. Simultaneously, system on chip (SoC) designs are increasing in which a large area of the exposure field typically contains dummy patterns and other features which are not electrically active. Knowing which defects will electrically impact device yield and performance can improve reticle manufacturing yield and cycle time -- resulting in lower reticle costs. This investigation examines the feasibility of using additional design data layers for die-to-database reticle inspection to determine in real time the relevance of a reticle defect by its location in the device (Smart InspectionTM). The impact to data preparation and inspection throughput is evaluated. The current prototype algorithm is built on the XPA and XPE die-to-database algorithms for chrome-on-glass and EPSM reticles, respectively. The algorithms implement variable sensitivity based on the additional design data regions. During defect review the defects are intelligently binned into the different predetermined design regions. Tests show the new Smart Inspection algorithm provides the capability of using higher than normal sensitivity in critical regions while reducing sensitivity in less critical regions to filter total defect counts and allow for the review of just defects that matter. Performance characterization of a variable sensitivity Smart Inspection algorithm is discussed in addition to the filtering of the total defect count during review to show the defects that matter to device performance. Using seven critical layer production reticles from a system on chip device we examine the applications of Smart Inspection by layer including active, poly, contact, metal and via layers. Data volume

  8. Optimum growth temperature determination for GaInSb/InAs strained layer superlattices

    SciTech Connect

    Davis, J.L.; Wagner, R.J.; Waterman, J.R.

    1993-05-01

    To determine the optimum growth temperature for GaInSb/InAs strained layer superlattices (SLS) a series of SLS was grown over the temperature range 357-433 {degrees}C. Temperatures were estimated by determining the absorption spectrum of the GaAs substrate, hence its band gap, and thus its temperature. SLS were evaluated by single crystal x-ray diffraction and interband magnetoabsorption (IMA) measurements. X-ray spectra showed as many as eight peaks due to the superlattice. The quality of the superlattices as indicated by the x-ray data had a well defined maximum between 390 and 410 {degrees}C. IMA measurements indicated band gaps from 85 to 154 meV. 15 refs., 2 figs., 1 tab.

  9. Determination of aminoglycosides in pharmaceutical formulations--I. Thin-layer chromatography.

    PubMed

    Sekkat, M; Fabre, H; Simeon de Buochberg, M; Mandrou, B

    1989-01-01

    A simple, fast and reliable procedure for the determination of seven major aminoglycosides in commercial formulations (injections, capsules, eye drops, solutions and ointments) is presented. The aminoglycosides are separated on silica gel plates then located with ninhydrin and analysed in situ using a chromatogram spectrophotometer. Linearity tests, repeatability (relative standard deviation congruent to 3.5%) detection limits (60-200 ng) were satisfactory for all the compounds. Recovery data in pharmaceutical formulations (expressed as the percentage of the label claim) from thin-layer chromatography (TLC) and microbiological assays did not give any significant difference (P = 0.05); this result shows that TLC is a reliable method for the determination of aminoglycosides as the drug substance and in pharmaceutical formulations. PMID:2490097

  10. Highly sensitive determination of chloramphenicol based on thin-layered MoS2/polyaniline nanocomposite.

    PubMed

    Yang, Tao; Chen, Huaiyin; Ge, Tong; Wang, Jin; Li, Weihua; Jiao, Kui

    2015-11-01

    The nanocomposite of molybdenum disulfide (MoS2) and polyaniline (PANI) was prepared through in situ polymerization of aniline on the surface and interlayer of thin-layered MoS2. Owing to the physisorption of aromatic aniline onto the basal plane of MoS2, the electrochemical properties of MoS2/PANI nanocomposite were improved. And a novel electrochemical sensor based on MoS2/PANI nanocomposite was used to determine chloramphenicol by differential pulse voltammetry, exhibiting excellent performance. The detection range was from 1×10(-7) mol L(-1) to 1×10(-4) mol L(-1), with a high sensitivity and a low detection limit of 6.9×10(-8) mol L(-1). In addition, this sensor can be used for the determination of chloramphenicol in real samples. PMID:26452965

  11. Shielding application of perturbation theory to determine changes in neutron and gamma doses due to changes in shield layers

    NASA Technical Reports Server (NTRS)

    Fieno, D.

    1972-01-01

    Perturbation theory formulas were derived and applied to determine changes in neutron and gamma-ray doses due to changes in various radiation shield layers for fixed sources. For a given source and detector position, the perturbation method enables dose derivatives with respect to density, or equivalently thickness, for every layer to be determined from one forward and one inhomogeneous adjoint calculation. A direct determination without the perturbation approach would require two forward calculations to evaluate the dose derivative due to a change in a single layer. Hence, the perturbation method for obtaining dose derivatives requires fewer computations for design studies of multilayer shields. For an illustrative problem, a comparison was made of the fractional change in the dose per unit change in the thickness of each shield layer in a two-layer spherical configuration as calculated by perturbation theory and by successive direct calculations; excellent agreement was obtained between the two methods.

  12. Annual layers in the Roosevelt Island (coastal Antarctica) ice core determined from conductivity and calcium measurements

    NASA Astrophysics Data System (ADS)

    Simonsen, Marius; Vallelonga, Paul; Kjær, Helle; Neff, Peter; Bertler, Nancy; Svensson, Anders; Dahl-Jensen, Dorthe; Riis, Marie

    2015-04-01

    The Roosevelt Island Climate Evolution (RICE) Project aims to determine the stability of the Ross Ice Shelf and thus the West Antarctic Ice Sheet in a warming world. A 764 m ice core (79.36° S, 161.71° W) was drilled in 2011-13 at the summit of the Roosevelt Island ice dome, a location surrounded by the Ross Ice Shelf. The site has high accumulation (0.26 m ice equivalent) and a mean annual temperature of -23 °C. From 2012 to 2014, continuous flow analysis (CFA) of the ice core enabled continuous measurements of conductivity, acidity, calcium and insoluble dust particle concentrations along the core. The RICE ice core features high background levels of sulphate and marine salts, due to the low altitude of the site (550 m asl) and its proximity to open ocean. At Roosevelt Island, calcium is influenced by both dust and marine salt inputs. By investigating the residual offset between conductivity and calcium, it has been possible to calculate non-sea salt conductivity and hence determine impurity layers deriving from volcanic eruptions. We present a preliminary chronology for the last 2000 years of deposition in the RICE ice core, composed of counted impurity layers and constrained by a limited number of large, well-dated volcanic eruptions.

  13. Measurement of doxorubicin-induced lipid peroxidation under the conditions that determine cytotoxicity in cultured tumor cells.

    PubMed

    Benchekroun, M N; Robert, J

    1992-03-01

    We have investigated doxorubicin-induced lipid peroxidation by the measure of malondialdehyde (MDA) formation in rat glioblastoma cells and human breast carcinoma cells in culture. There was a significant production of MDA when the cells were incubated with pharmacologically relevant doxorubicin concentrations, i.e., concentrations that produce a significant cytotoxicity (0.1 micrograms/ml). At equitoxic doses, vincristine provided no lipid peroxidation, indicating that MDA formation is not a consequence of cell death. Doxorubicin-induced lipid peroxidation was maximal 24 h after incubation of the cells with doxorubicin, indicating that a delay was necessary for the free radical-mediated membrane damage induced by doxorubicin. In the presence of alpha-tocopherol in the culture medium, the doxorubicin-induced MDA formation was inhibited. The development of this method will help in defining the role of free radicals and lipid peroxidation in the cytotoxicity of doxorubicin. PMID:1632521

  14. Lipid body formation plays a central role in cell fate determination during developmental differentiation of Myxococcus xanthus

    PubMed Central

    Ring, Michael W.; McHugh, Colleen A.; Schwär, Gertrud; Bode, Edna; Krug, Daniel; Altmeyer, Matthias O.; Lu, Jeff Zhiqiang

    2010-01-01

    Summary Cell differentiation is widespread during the development of multicellular organisms, but rarely observed in prokaryotes. One example of prokaryotic differentiation is the Gramnegative bacterium Myxococcus xanthus. In response to starvation, this gliding bacterium initiates a complex developmental program that results in the formation of spore-filled fruiting bodies. How the cells metabolically support the necessary complex cellular differentiation from rod-shaped vegetative cells into spherical spores is unknown. Here, we present evidence that intra-cellular lipid bodies provide the necessary metabolic fuel for the development of spores. Formed at the onset of starvation, these lipid bodies gradually disappear until they are completely used up by the time the cells have become mature spores. Moreover, it appears that lipid body formation in M. xanthus is an important initial step indicating cell fate during differentiation. Upon starvation, two subpopulations of cells occur: cells that form lipid bodies invariably develop into spores, while cells that do not form lipid bodies end up becoming peripheral rods, which are cells that lack signs of morphological differentiation and stay in a vegetative-like state. These data indicate that lipid bodies not only fuel cellular differentiation but that their formation represents the first known morphological sign indicating cell fate during differentiation. PMID:19788540

  15. Determination of nitrogen to carbon abundance ratios from transition layer emission lines

    NASA Technical Reports Server (NTRS)

    Boehm-Vitense, Erika

    1992-01-01

    We have finished studying the nitrogen to carbon abundance ratios for stars with different effective temperatures T(sub eff) and luminosities using transition layer emission lines and using spectra available in the IUE archives. The N/C abundance ratio determinations using transition layer emission lines are as accurate as the photospheric abundance determinations as found by comparison of results obtained by both methods for the same stars. Our measurements confirm photospheric abundance determinations in regions of the HR diagram where they can be obtained. Our studies have extended the temperature range to higher temperatures. They have shown the exact positions in the HR diagram where the mixing due to the outer convection zones reaches deep enough to bring nuclear processed material to the surface. This occurs at effective temperatures which are higher by delta log T(sub eff) approximately 0.04 or roughly 400 K than expected theoretically. Since the depth of the convection zone increases rapidly with decreasing T(sub eff) this may indicate considerable overshoot beyond the lower boundary of the convection zone. Our N/C abundance ratio determinations from transition layer emission lines have confirmed that the actual enrichment observed for some cool giants is larger than expected theoretically, again indicating a larger degree of mixing in several stars either from below or from above. For the supergiants it probably indicates overshoot above the convective core in the progenitor main sequence stars. For the more massive giants this may also be the case, though we did not find a correlation between delta log N/C and the absolute magnitudes, but these are rather uncertain. As byproducts of these studies we also found anomalies in Si/C and N/C abundance ratios for F giants which can be understood as the relict of surface abundance changes for their main sequence progenitors due to diffusion. This anomaly disappears for G giants, for which the depths of the

  16. Mixing layer height measurements determines influence of meteorology on air pollutant concentrations in urban area

    NASA Astrophysics Data System (ADS)

    Schäfer, Klaus; Blumenstock, Thomas; Bonn, Boris; Gerwig, Holger; Hase, Frank; Münkel, Christoph; Nothard, Rainer; von Schneidemesser, Erika

    2015-10-01

    Mixing layer height (MLH) is a key parameter to determine the influence of meteorological parameters upon air pollutants such as trace gas species and particulate concentrations near the surface. Meteorology, and MLH as a key parameter, affect the budget of emission source strengths, deposition, and accumulation. However, greater possibilities for the application of MLH data have been identified in recent years. Here, the results of measurements in Berlin in 2014 are shown and discussed. The concentrations of NO, NO2, O3, CO, PM1, PM2.5, PM10 and about 70 volatile organic compounds (anthropogenic and biogenic of origin) as well as particle size distributions and contributions of SOA and soot species to PM were measured at the urban background station of the Berlin air quality network (BLUME) in Nansenstr./Framstr., Berlin-Neukölln. A Vaisala ceilometer CL51, which is a commercial mini-lidar system, was applied at that site to detect the layers of the lower atmosphere in real time. Special software for these ceilometers with MATLAB provided routine retrievals of MLH from vertical profiles of laser backscatter data. Five portable Bruker EM27/SUN FTIR spectrometers were set up around Berlin to detect column averaged abundances of CO2 and CH4 by solar absorption spectrometry. Correlation analyses were used to show the coupling of temporal variations of trace gas compounds and PM with MLH. Significant influences of MLH upon NO, NO2, PM10, PM2.5, PM1 and toluene (marker for traffic emissions) concentrations as well as particle number concentrations in the size modes 70 - 100 nm, 100 - 200 nm and 200 - 500 nm on the basis of averaged diurnal courses were found. Further, MLH was taken as important auxiliary information about the development of the boundary layer during each day of observations, which was required for the proper estimation of CO2 and CH4 source strengths from Berlin on the basis of atmospheric column density measurements.

  17. Ferritin-stimulated lipid peroxidation, lysosomal leak, and macroautophagy promote lysosomal "metastability" in primary hepatocytes determining in vitro cell survival.

    PubMed

    Krenn, Margit A; Schürz, Melanie; Teufl, Bernhard; Uchida, Koji; Eckl, Peter M; Bresgen, Nikolaus

    2015-03-01

    Several pathologies are associated with elevated levels of serum ferritin, for which growth inhibitory properties have been reported; however, the underlying mechanisms are still poorly defined. Previously we have described cytotoxic properties of isoferritins released from primary hepatocytes in vitro, which induce apoptosis in an iron and oxidative stress-dependent mode. Here we show that this ferritin species stimulates endosome clustering and giant endosome formation in primary hepatocytes accompanied by enhanced lysosomal membrane permeability (LMP). In parallel, protein modification by lipid peroxidation-derived 4-hydroxynonenal (HNE) is strongly promoted by ferritin, the HNE-modified proteins (HNE-P) showing remarkable aggregation. Emphasizing the prooxidant context, GSH is rapidly depleted and the GSH/GSSG ratio is substantially declining in ferritin-treated cells. Furthermore, ferritin triggers a transient upregulation of macroautophagy which is abolished by iron chelation and apparently supports HNE-P clearance. Macroautophagy inhibition by 3-methyladenine strongly amplifies ferritin cytotoxicity in a time- and concentration-dependent mode, suggesting an important role of macroautophagy on cellular responses to ferritin endocytosis. Moreover, pointing at an involvement of lysosomal proteolysis, ferritin cytotoxicity and lysosome fragility are aggravated by the protease inhibitor leupeptin. In contrast, EGF which suppresses ferritin-induced cell death attenuates ferritin-mediated LMP. In conclusion, we propose that HNE-P accumulation, lysosome dysfunction, and macroautophagy stimulated by ferritin endocytosis provoke lysosomal "metastability" in primary hepatocytes which permits cell survival as long as in- and extrinsic determinants (e.g., antioxidant availability, damage repair, EGF signaling) keep the degree of lysosomal destabilization below cell death-inducing thresholds. PMID:25532933

  18. Age determination in manatees using growth-layer-group counts in bone

    USGS Publications Warehouse

    Marmontel, M.; O'Shea, T.J.; Kochman, H.I.; Humphrey, S.R.

    1996-01-01

    Growth layers were observed in histological preparations of bones of known-age, known minimum-age, and tetracycline-marked free-ranging and captive Florida manatees (Trichechus manatus latirostris), substantiating earlier preliminary findings of other studies. Detailed analysis of 17 new case histories showed that growth-layer group (GLG) counts in the periotic bone were consistent with known age, or time since tetracycline administration, but were less reliable in other bones. GLG counts were also made in periotic bones of 1,196 Florida manatees of unknown age found dead from 1974 through 1991. These counts were conducted in order to assess variability and to determine relationships among estimated age, size, sex, and degree of bone resorption. Resorption can interfere with accuracy of GLG counts. This effect does not occur until ages greater than about 15 yr and body lengths greater than 300 cm are attained. GLGs were also observed in periotic bones of Antillean manatees (Trichechus manatus manatus) but were not validated against known-age specimens. Use of GLG counts in the periotic bone is suitable for application to studies of population dynamics and other age-related aspects of manatee biology.

  19. DIRECT DETERMINATION OF THE STACKING ORDER IN GD2O3 EPI LAYERS ON GAAS.

    SciTech Connect

    YACOBY,Y.; SOWWAN,M.; PINDAK,R.; CROSS,J.; WALKO,D.; STERN,E.; PITNEY,J.; MACHARRIE,R.; HONG,M.; CLARKE,R.

    2002-12-06

    We have used Coherent Bragg Rod Analysis (COBRA) to investigate the atomic structure of a 5.6 nm thick Gd{sub 2}O{sub 3} film epitaxially grown on a (100) GaAs substrate. COBRA is a method to directly obtain the structure of systems periodic in two-dimensions by determining the complex scattering factors along the substrate Bragg rods. The system electron density and atomic structure are obtained by Fourier transforming the complex scattering factors into real space. The results show that the stacking order of the first seven Gd{sub 2}O{sub 3} film layers resembles the stacking order of Ga and As layers in GaAs then changes to the stacking order of cubic bulk Gd{sub 2}O{sub 3}. This behavior is distinctly different from the measured stacking order in a 2.7 nm thick Gd{sub 2}O{sub 3} in which the GaAs stacking order persists throughout the entire film.

  20. Oral mucosal lipids are antibacterial against Porphyromonas gingivalis, induce ultrastructural damage, and alter bacterial lipid and protein compositions

    PubMed Central

    Fischer, Carol L; Walters, Katherine S; Drake, David R; Dawson, Deborah V; Blanchette, Derek R; Brogden, Kim A; Wertz, Philip W

    2013-01-01

    Oral mucosal and salivary lipids exhibit potent antimicrobial activity for a variety of Gram-positive and Gram-negative bacteria; however, little is known about their spectrum of antimicrobial activity or mechanisms of action against oral bacteria. In this study, we examine the activity of two fatty acids and three sphingoid bases against Porphyromonas gingivalis, an important colonizer of the oral cavity implicated in periodontitis. Minimal inhibitory concentrations, minimal bactericidal concentrations, and kill kinetics revealed variable, but potent, activity of oral mucosal and salivary lipids against P. gingivalis, indicating that lipid structure may be an important determinant in lipid mechanisms of activity against bacteria, although specific components of bacterial membranes are also likely important. Electron micrographs showed ultrastructural damage induced by sapienic acid and phytosphingosine and confirmed disruption of the bacterial plasma membrane. This information, coupled with the association of treatment lipids with P. gingivalis lipids revealed via thin layer chromatography, suggests that the plasma membrane is a likely target of lipid antibacterial activity. Utilizing a combination of two-dimensional in-gel electrophoresis and Western blot followed by mass spectroscopy and N-terminus degradation sequencing we also show that treatment with sapienic acid induces upregulation of a set of proteins comprising a unique P. gingivalis stress response, including proteins important in fatty acid biosynthesis, metabolism and energy production, protein processing, cell adhesion and virulence. Prophylactic or therapeutic lipid treatments may be beneficial for intervention of infection by supplementing the natural immune function of endogenous lipids on mucosal surfaces. PMID:23867843

  1. Determining the Effective Density and Stabilizer Layer Thickness of Sterically Stabilized Nanoparticles

    PubMed Central

    2016-01-01

    A series of model sterically stabilized diblock copolymer nanoparticles has been designed to aid the development of analytical protocols in order to determine two key parameters: the effective particle density and the steric stabilizer layer thickness. The former parameter is essential for high resolution particle size analysis based on analytical (ultra)centrifugation techniques (e.g., disk centrifuge photosedimentometry, DCP), whereas the latter parameter is of fundamental importance in determining the effectiveness of steric stabilization as a colloid stability mechanism. The diblock copolymer nanoparticles were prepared via polymerization-induced self-assembly (PISA) using RAFT aqueous emulsion polymerization: this approach affords relatively narrow particle size distributions and enables the mean particle diameter and the stabilizer layer thickness to be adjusted independently via systematic variation of the mean degree of polymerization of the hydrophobic and hydrophilic blocks, respectively. The hydrophobic core-forming block was poly(2,2,2-trifluoroethyl methacrylate) [PTFEMA], which was selected for its relatively high density. The hydrophilic stabilizer block was poly(glycerol monomethacrylate) [PGMA], which is a well-known non-ionic polymer that remains water-soluble over a wide range of temperatures. Four series of PGMAx–PTFEMAy nanoparticles were prepared (x = 28, 43, 63, and 98, y = 100–1400) and characterized via transmission electron microscopy (TEM), dynamic light scattering (DLS), and small-angle X-ray scattering (SAXS). It was found that the degree of polymerization of both the PGMA stabilizer and core-forming PTFEMA had a strong influence on the mean particle diameter, which ranged from 20 to 250 nm. Furthermore, SAXS was used to determine radii of gyration of 1.46 to 2.69 nm for the solvated PGMA stabilizer blocks. Thus, the mean effective density of these sterically stabilized particles was calculated and determined to lie between 1.19 g

  2. Rapid determination of lipid peroxidation using a novel pyridoxamine-participating ferrous oxidation-sulfosalicylic acid spectrophotometric method.

    PubMed

    Chen, Jingnan; Cai, Danqian; Zhang, Yu

    2016-11-15

    A novel method is developed to rapidly analyze lipid peroxidation in edible oils and fatty foods at room temperature, which is called the pyridoxamine-participating ferrous oxidation-sulfosalicylic acid (PFOS) method. The PFOS method evaluates the lipid peroxide value colorimetrically via detecting the pyridoxamine-mediated pigment produced by 5-sulfosalicylic acid and Fe(3+) at 500nm, while the latter is converted from Fe(2+) in the presence of lipid peroxides. The optimized formulation was ethanol (70%, v/v), Fe(2+) (4mmol/L), 5-sulfosalicylic acid (40mmol/L) and pyridoxamine (18mmol/L). The limit of quantitation is 0.087mmol Fe(3+)/L with acceptable reproducibility. In addition, current method has a significant linear correlation with both conventional thiobarbituric acid (R(2)=0.9999) and ferric thiocyanate assays (R(2)=0.9675). This method offers a rapid technique for evaluating lipid peroxidation without heating and sophisticated instrumental procedures. Besides, current method provides a new option to evaluate the lipid peroxidation state and improve the reproducibility of ferrous-oxidation. PMID:27283678

  3. Determination of free bile acids in pharmaceuticals by thin layer chromatography and high performance liquid chromatography.

    PubMed

    Novaković, J; Tvrzická, E; Razić, S

    1998-11-01

    High-performance liquid chromatography with evaporative light scattering detection (HPLC-ELSD) and thin layer chromatography with flame ionization detection (TLC-FID) have been applied to the separation of five main free bile acids present in humans: cholic (CA), chenodeoxycholic (CDCA), deoxycholic (DCA), lithocholic (LCA) and ursodeoxycholic (UDCA) acid. HPLC separation was performed on Biospher Si 100 column using a mixture of n-heptane, isopropanol, ethylacetate, methanol and glacial acetic acid as a mobile phase. All the compounds were separated in less than 12 minutes by using a gradient elution mode. TLC-FID separation was performed on S-II Chromarods with a mixture of isooctane, ethylacetate and glacial acetic acid as a mobile phase. HPLC-ELSD method was applied to the determination of CDCA and UDCA in pharmaceuticals and their purity control when LCA, DCA and CA were considered as impurities. PMID:9880946

  4. Determining fatty acids by desorption/ionization mass spectrometry using thin-layer chromatography substrates.

    PubMed

    Mirabelli, Mario F; Coviello, Giuseppe; Volmer, Dietrich A

    2015-06-01

    In this study, we demonstrate the application of ambient mass spectrometry for measuring fatty acids from various biological sample matrices such as olive oil, fish oil, salmon, and human serum. Optimum performance was obtained after spotting samples onto thin-layer chromatography (TLC) plates as sample substrates for a custom-built solvent-assisted desorption/ionization mass spectrometry (DI-MS) interface. Good to excellent linearities (coefficients of determination, 0.9856 to 0.9977) and reproducibilities (average 6 % relative standard deviation (RSD) using syringe deposition) were obtained after application of an internal standard. Signal suppression phenomena were minimized by separating the analytes by TLC to some extent prior to DI-MS, leading to a fourfold increase of signal-to-noise ratios as compared to single spot mixture analysis without TLC separation. Graphical Abstract Solvent-assisted desorption/ionization-mass spectrometry. PMID:25814272

  5. Lidar determination of winds by aerosol inhomogeneities: motion velocity in the planetary boundary layer.

    PubMed

    Kolev, I; Parvanov, O; Kaprielov, B

    1988-06-15

    The paper presents results from lidar measurements of wind velocity in the planetary boundary layer using correlation data processing. Two lidars are used in our experiments: a ruby lidar operating along slant paths and a YAG:Nd lidar operating for near vertical sounding used by us for the first time. On the basis of our experience the optimal sizes of aerosol inhomogeneities (30-300 m), the duration of the experiments (2-10 min), and the repetition rate of laser shots (fractions of hertz to several hertz) are determined. The results are compared to independent data obtained from anemometer measurements, theodolite- and radar-tracked pilot balloons. The range of differences is ~1-2 m/s in speed and 10-15 degrees in direction. Preliminary results from the use of lidar data to remotely sound the wind speed for various atmospheric stratifications and synoptic situations are described as well. PMID:20531786

  6. Determination of the thickness and orientation of few-layer tungsten ditelluride using polarized Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Kim, Minjung; Han, Songhee; Kim, Jung Hwa; Lee, Jae-Ung; Lee, Zonghoon; Cheong, Hyeonsik

    2016-09-01

    Orthorhombic tungsten ditelluride (WTe2), with a distorted 1T structure, exhibits a large magnetoresistance that depends on the orientation, and its electrical characteristics changes from semimetallic to insulating as the thickness decreases. Through polarized Raman spectroscopy in combination with transmission electron diffraction, we establish a reliable method to determine the thickness and crystallographic orientation of few-layer WTe2. The Raman spectrum shows a pronounced dependence on the polarization of the excitation laser. We found that the separation between two Raman peaks at ∼90 cm‑1 and at 80–86 cm‑1, depending on thickness, is a reliable fingerprint for determination of the thickness. For determination of the crystallographic orientation, the polarization dependence of the A 1 modes, measured with the 632.8 nm excitation, turns out to be the most reliable. We also discovered that the polarization behaviors of some of the Raman peaks depend on the excitation wavelength as well as thickness, indicating a close interplay between the band structure and anisotropic Raman scattering cross section.

  7. Optimization of the C11-BODIPY(581/591) dye for the determination of lipid oxidation in Chlamydomonas reinhardtii by flow cytometry.

    PubMed

    Cheloni, Giulia; Slaveykova, Vera I

    2013-10-01

    Lipid oxidation is a recognized end point for the study of oxidative stress and is an important parameter to describe the mode of micropollutant action on aquatic microorganisms. Therefore, the development of quick and reliable methodologies probing the oxidative stress and damage in living cells is highly sought. In the present proof-of-concept work, we examined the potential of the fluorescent dye C11-BODIPY(591/581) to probe lipid oxidation in the green microalga Chlamydomonas reinhardtii. C11-BODIPY(591/581) staining was combined with flow cytometry measurements to obtain multiparameter information on cellular features and oxidative stress damage within single cells. First, staining conditions were optimized by exploring the capability of the dye to stain algal cells under increasing cell and dye concentrations and different staining procedures. Then lipid oxidation in algae induced by short- and long-term exposures to the three metallic micropollutants, copper, mercury, and nanoparticulate copper oxide, and the two organic contaminants, diethyldithiocarbamate (DDC) and diuron was determined. In this work we pointed out C11-BODIPY(591/581) applicability in a wide range of exposure conditions, including studies of oxidation as a function of time and that it is suitable for in vivo measurements of lipid oxidation due to its high permeation and stability in cells and its low interference with algal autofluorescence. © 2013 International Society for Advancement of Cytometry. PMID:23943236

  8. Evaluating quality and its determinants in lipid control for secondary prevention of heart disease and stroke in primary care: a study in an inner London Borough

    PubMed Central

    Dodhia, Hiten; Kun, Liu; Logan Ellis, Hugh; Crompton, James; Wierzbicki, Anthony S; Williams, Helen; Hodgkinson, Anna; Balazs, John

    2015-01-01

    Objectives To assess quality of management and determinants in lipid control for secondary prevention of cardiovascular disease (CVD) using multilevel regression models. Design Cross-sectional study. Setting Inner London borough, with a primary care registered population of 378 000 (2013). Participants 48/49 participating general practices with 7869 patients on heart disease/stroke registers were included. Outcome measures (1) Recording of current total cholesterol levels and lipid control according to national evidence-based standards. (2) Assessment of quality by age, sex, ethnicity, deprivation, presence of other risks or comorbidity in meeting both lipid measurement and control standards. Results Some process standards were not met. Patients with a current cholesterol measurement >5 mmol/L were less likely to have a current statin prescription (adjusted OR=3.10; 95% CI 2.70 to 3.56). They were more likely to have clustering of other CVD risk factors. Women were significantly more likely to have raised cholesterol after adjustment for other factors (adjusted OR=1.74; 95% CI 1.53 to 1.98). Conclusions In this study, the key factor that explained poor lipid control in people with CVD was having no current prescription record of a statin. Women were more likely to have poorly controlled cholesterol (independent of comorbid risk factors and after adjusting for age, ethnicity, deprivation index and practice-level variation). Women with CVD should be offered statin prescription and may require higher statin dosage for improved control. PMID:26656014

  9. Alteration of interleaflet coupling due to compounds displaying rapid translocation in lipid membranes

    PubMed Central

    Reigada, Ramon

    2016-01-01

    The spatial coincidence of lipid domains at both layers of the cell membrane is expected to play an important role in many cellular functions. Competition between the surface interleaflet tension and a line hydrophobic mismatch penalty are conjectured to determine the transversal behavior of laterally heterogeneous lipid membranes. Here, by a combination of molecular dynamics simulations, a continuum field theory and kinetic equations, I demonstrate that the presence of small, rapidly translocating molecules residing in the lipid bilayer may alter its transversal behavior by favoring the spatial coincidence of similar lipid phases. PMID:27596355

  10. Alteration of interleaflet coupling due to compounds displaying rapid translocation in lipid membranes.

    PubMed

    Reigada, Ramon

    2016-01-01

    The spatial coincidence of lipid domains at both layers of the cell membrane is expected to play an important role in many cellular functions. Competition between the surface interleaflet tension and a line hydrophobic mismatch penalty are conjectured to determine the transversal behavior of laterally heterogeneous lipid membranes. Here, by a combination of molecular dynamics simulations, a continuum field theory and kinetic equations, I demonstrate that the presence of small, rapidly translocating molecules residing in the lipid bilayer may alter its transversal behavior by favoring the spatial coincidence of similar lipid phases. PMID:27596355

  11. In Vitro Amphotericin B Susceptibility of Malassezia pachydermatis Determined by the CLSI Broth Microdilution Method and Etest Using Lipid-Enriched Media

    PubMed Central

    Álvarez-Pérez, Sergio; Peláez, Teresa; Cutuli, Maite; García, Marta E.

    2014-01-01

    We determined the in vitro amphotericin B susceptibility of 60 Malassezia pachydermatis isolates by the CLSI broth microdilution method and the Etest using lipid-enriched media. All isolates were susceptible at MICs of ≤1 μg/ml, confirming the high activity of amphotericin B against this yeast species. Overall, the essential agreement between the tested methods was high (80% and 96.7% after 48 h and 72 h, respectively), and all discrepancies were regarded as nonsubstantial. PMID:24752258

  12. Determination of the rate of rapid lipid transfer induced by poly(ethylene glycol) using the SLM Fourier transform phase and modulation spectrofluorometer.

    PubMed

    Burgess, S W; Wu, J R; Swift, K; Lentz, B R

    1991-06-01

    Rate constants were determined for the transfer of the fluorescent lipid probe 1-palmitoyl-2-[[2-[4-(6-phenyl-trans-1,3,5-hexatrienyl)phenyl]ethyl] oxy]carbonyl]-3-sn-phosphatidylcholine (DPHpPC) between large, unilamellar extrusion vesicles composed either of dipalmitoyl phosphatidylcholine (DPPC) or of DPPC mixed with a small amount (0.5 mol%) of lyso phosphatidylcholine (Lyso PC). Transfer of the lipid probe in the presence of varying concentrations of poly(ethylene glycol) (PEG) was monitored using the SLM 48000-MHF Multi-Harmonic Fourier Transform phase and modulation spectrofluorometer to collect multifrequency phase and modulation fluorescence data sets on a subsecond time scale. The unique ability of this instrument to yield accurate fluorescence lifetime data on this time scale allowed transfer to be detected in terms of a time-dependent change in the fluorescent lifetime distribution associated with the lipid-like DPHpPC probe. This probe demonstrates two short fluoresence decay times (ca. 1.1-1.4 and 4.3-4.8 ns) in a probe-rich environment but a single long lifetime (ca. 7 ns) in a probe-poor environment. A simple two-state model for initial lipid transfer was used to analyze the multifrequency data sets collected over a 4-s time frame to obtain the time rate of change of the concentrations of donor and acceptor probe populations following rapid mixing of vesicles with PEG. The ability to measure fluorescence lifetimes on this time scale has allowed us to show that the of rate of lipid transfer increased dramatically at 35% PEG in both fusing and nonfusing vesicle systems. These results are interpreted in terms of a distinct interbilayer structure associated with intimate bilayer contact induced by high and potentially fusogenic concentrations of PEG. PMID:24242960

  13. [Lipid makeup of the organs of normal white rats].

    PubMed

    Ilinov, P; Goranov, I

    1980-01-01

    The lipid composition of some tissues and organs of Wistar rats fed on control diet (conventional palets) was studied by a modified thin-layer chromatographic technique for determination of lipid groups and by gas chromatographic analysis of the fatty acid composition of triglycerides and phospholipids in the different organs. Data are adduced on the content of total lipids, esterified cholesterol, triglycerides, fatty acids, free cholesterol and phospholipids in the following organs and tissues: plasma, liver, lung, heart, muscle, adipose tissue, testes, brain, adrenals, bone marrow, thymus, red cells and lymph nodes. The fatty acid composition of these organs, resp. of their phospholipids and triglycerides was also determined. Data are given on five fatty acids, viewed from a physiological background. The data obtained in this assay may be used in comparative studies of lipid changes in rat organs and tissues. PMID:7379729

  14. The structure of the lipid-embedded potassium channel voltage sensor determined by double-electron–electron resonance spectroscopy

    PubMed Central

    Vamvouka, Magdalini; Cieslak, John; Van Eps, Ned; Hubbell, Wayne; Gross, Adrian

    2008-01-01

    A four-pulse electron paramagnetic resonance experiment was used to measure long-range inter-subunit distances in reconstituted KvAP, a voltage-dependent potassium (Kv) channel. The measurements have allowed us to reach the following five conclusions about the native structure of the voltage sensor of KvAP. First, the S1 helix of the voltage sensor engages in a helix packing interaction with the pore domain. Second, the crystallographically observed antiparallel helix-turn-helix motif of the voltage-sensing paddle is retained in the membrane-embedded voltage sensor. Third, the paddle is oriented in such a way as to expose one face to the pore domain and the opposite face to the membrane. Fourth, the paddle and the pore domain appear to be separated by a gap that is sufficiently wide for lipids to penetrate between the two domains. Fifth, the critical voltage-sensing arginine residues on the paddle appear to be lipid exposed. These results demonstrate the importance of the membrane for the native structure of Kv channels, suggest that lipids are an integral part of their native structure, and place the voltage-sensing machinery into a complex lipid environment near the pore domain. PMID:18287283

  15. Lanolin-derived lipid mixtures mimic closely the lipid composition and organization of vernix caseosa lipids.

    PubMed

    Rissmann, Robert; Oudshoorn, Marion H M; Kocks, Elise; Hennink, Wim E; Ponec, Maria; Bouwstra, Joke A

    2008-10-01

    The aim of the present study was to use semi-synthetic lipid mixtures to mimic the complex lipid composition, organization and thermotropic behaviour of vernix caseosa (VC) lipids. As VC shows multiple protecting and barrier supporting properties before and after birth, it is suggested that a VC substitute could be an innovative barrier cream for barrier deficient skin. Lanolin was selected as the source of the branched chain sterol esters and wax esters--the main lipid classes of VC. Different lipid fractions were isolated from lanolin and subsequently mixed with squalene, triglycerides, cholesterol, ceramides and fatty acids to generate semi-synthetic lipid mixtures that mimic the lipid composition of VC, as established by high-performance thin-layer chromatography. Differential scanning calorimetry and Fourier transform infrared spectroscopy investigations revealed that triglycerides play an important role in the (lateral) lipid organization and thermotropic behaviour of the synthetic lipid mixtures. Excellent resemblance of VC lipids was obtained when adding unsaturated triglycerides. Moreover, these lipid mixtures showed similar long range ordering as VC. The optimal lipid mixture was evaluated on tape-stripped hairless mouse skin in vivo. The rate of barrier recovery was increased and comparable to VC lipid treatment. PMID:18655769

  16. Quantitative Determination of Photosynthetic Pigments in Green Beans Using Thin-Layer Chromatography and a Flatbed Scanner as Densitometer

    ERIC Educational Resources Information Center

    Valverde, Juan; This, Herve; Vignolle, Marc

    2007-01-01

    A simple method for the quantitative determination of photosynthetic pigments extracted from green beans using thin-layer chromatography is proposed. Various extraction methods are compared, and it is shown how a simple flatbed scanner and free software for image processing can give a quantitative determination of pigments. (Contains 5 figures.)

  17. Quantitative determination of fluoxetine in human serum by high performance thin layer chromatography.

    PubMed

    Mennickent, Sigrid; Fierro, Ricardo; Vega, Mario; De Diego, Marta; Godoy, C Gloria

    2010-07-01

    A high performance thin layer chromatographic method was developed and validated for the quantification of fluoxetine in human serum. Fluoxetine was extracted by liquid-liquid extraction method with diethyl ether as extraction solvent. Imipramine was used as internal standard. The chromatographic separation was achieved on precoated silica gel F 254 high performance thin layer chromatographic plates using a mixture of toluene/acetic acid glacial (4:5 v/v) as mobile phase. 4-Dimethylamino-azobenzene-4-sulphonyl chloride was used as derivatization reagent. Densitometric detection was done at 272 nm. The method was linear between 12.5 and 87.5 ng/spot, corresponding to 0.05 and 0.35 ng/microL of fluoxetine in human serum after extraction process and applying 25 microL to the chromatographic plates. The method correlation coefficient was 0.999. The intra-assay and inter-assay precisions, expressed as the RSD, were in the range of 0.70-2.01% (n=3) and 0.81-3.90% (n=9), respectively. The LOD was 0.23 ng, and the LOQ was 0.70 ng. The method proved be accurate, with a recovery between 94.75 and 98.95%, with a RSD not higher than 3.61% and was selective for the active principle tested. This method was successfully applied to quantify fluoxetine in patient serum samples. In conclusion, the method is useful for quantitative determination of fluoxetine in human serum. PMID:20533339

  18. Lipid and fatty acid compositions of cod ( Gadus morhua), haddock ( Melanogrammus aeglefinus) and halibut ( Hippoglossus hippoglossus)

    NASA Astrophysics Data System (ADS)

    Zeng, Duan; Mai, Kangsen; Ai, Qinghui; Milley, Joyce E.; Lall, Santosh P.

    2010-12-01

    This study was conducted to compare lipid and fatty acid composition of cod, haddock and halibut. Three groups of cod (276 g ± 61 g), haddock (538 g ± 83 g) and halibut (3704 g ± 221 g) were maintained with commercial feeds mainly based on fish meal and marine fish oil for 12 weeks prior to sampling. The fatty acid compositions of muscle and liver were determined by GC/FID after derivatization of extracted lipids into fatty acid methyl esters (FAME). Lipids were also fractionated into neutral and polar lipids using Waters silica Sep-Pak?. The phospholipid fraction was further separated by high-performance thin-layer chromatography (HPTLC) and the FAME profile was obtained. Results of the present study showed that cod and haddock were lean fish and their total muscle lipid contents were 0.8% and 0.7%, respectively, with phospholipid constituting 83.6% and 87.5% of the total muscle lipid, respectively. Halibut was a medium-fat fish and its muscle lipid content was 8%, with 84% of the total muscle lipid being neutral lipid. Total liver lipid contents of cod, haddock and halibut were 36.9%, 67.2% and 30.7%, respectively, of which the neutral lipids accounted for the major fraction (88.1%-97.1%). Polyunsaturated fatty acids were the most abundant in cod and haddock muscle neutral lipid. Monounsaturated fatty acid level was the highest in halibut muscle neutral lipid. Fatty acid compositions of phospholipid were relatively constant. In summary, the liver of cod and haddock as lean fish was the main lipid reserve organ, and structural phospholipid is the major lipid form in flesh. However, as a medium-fat fish, halibut stored lipid in both their liver and muscle.

  19. A shielding application of perturbation theory to determine changes in neutron and gamma doses due to changes in shield layers

    NASA Technical Reports Server (NTRS)

    Fieno, D.

    1972-01-01

    Perturbation theory for fixed sources was applied to radiation shielding problems to determine changes in neutron and gamma ray doses due to changes in various shield layers. For a given source and detector position, the perturbation method enables dose derivatives due to all layer changes to be determined from one forward and one inhomogeneous adjoint calculation. The direct approach requires two forward calculations for the derivative due to a single layer change. Hence, the perturbation method for a obtaining dose derivatives permits an appreciable savings in computation for a multilayered shield. A comparison was made of the fractional change in the dose per unit change in shield layer thickness as calculated by perturbation theory and by successive direct calculations; excellent agreement was obtained between the two methods.

  20. A shielding application of perturbation theory to determine changes in neutron and gamma doses due to changes in shield layers

    NASA Technical Reports Server (NTRS)

    Fieno, D.

    1972-01-01

    The perturbation theory for fixed sources was applied to radiation shielding problems to determine changes in neutron and gamma ray doses due to changes in various shield layers. For a given source and detector position the perturbation method enables dose derivatives due to all layer changes to be determined from one forward and one inhomogeneous adjoint calculation. The direct approach requires two forward calculations for the derivative due to a single layer change. Hence, the perturbation method for obtaining dose derivatives permits an appreciable savings in computation for a multilayered shield. For an illustrative problem, a comparison was made of the fractional change in the dose per unit change in the thickness of each shield layer as calculated by perturbation theory and by successive direct calculations; excellent agreement was obtained between the two methods.

  1. Determination of optical characteristics of a dispersive medium from the measured relative angular distribution of radiation emerging from a layer

    SciTech Connect

    Berdnik, V.V.; Loiko, V.A.; Ivanov, A.P.

    1995-04-01

    A method is suggested that allows one to determine the photon survival probability and the coefficients in the Legendre polynomial expansion of the scattering indicatrix from the relative intensities of radiation emerging from a layer. The method consists in solving the nonlinear equations of the radiation-transfer theory for the radiation intensities at layer boundaries. Estimates are also given for the errors in the restoration procedure.

  2. Determination of effective mechanical properties of a double-layer beam by means of a nano-electromechanical transducer

    SciTech Connect

    Hocke, Fredrik; Pernpeintner, Matthias; Gross, Rudolf; Zhou, Xiaoqing; Kippenberg, Tobias J.; Schliesser, Albert; Huebl, Hans

    2014-09-29

    We investigate the mechanical properties of a doubly clamped, double-layer nanobeam embedded into an electromechanical system. The nanobeam consists of a highly pre-stressed silicon nitride and a superconducting niobium layer. By measuring the mechanical displacement spectral density both in the linear and the nonlinear Duffing regime, we determine the pre-stress and the effective Young's modulus of the nanobeam. An analytical double-layer model quantitatively corroborates the measured values. This suggests that this model can be used to design mechanical multilayer systems for electro- and optomechanical devices, including materials controllable by external parameters such as piezoelectric, magnetostrictive, or in more general multiferroic materials.

  3. Determination of Surface Potential and Electrical Double-Layer Structure at the Aqueous Electrolyte-Nanoparticle Interface

    NASA Astrophysics Data System (ADS)

    Brown, Matthew A.; Abbas, Zareen; Kleibert, Armin; Green, Richard G.; Goel, Alok; May, Sylvio; Squires, Todd M.

    2016-01-01

    The structure of the electrical double layer has been debated for well over a century, since it mediates colloidal interactions, regulates surface structure, controls reactivity, sets capacitance, and represents the central element of electrochemical supercapacitors. The surface potential of such surfaces generally exceeds the electrokinetic potential, often substantially. Traditionally, a Stern layer of nonspecifically adsorbed ions has been invoked to rationalize the difference between these two potentials; however, the inability to directly measure the surface potential of dispersed systems has rendered quantitative measurements of the Stern layer potential, and other quantities associated with the outer Helmholtz plane, impossible. Here, we use x-ray photoelectron spectroscopy from a liquid microjet to measure the absolute surface potentials of silica nanoparticles dispersed in aqueous electrolytes. We quantitatively determine the impact of specific cations (Li+ , Na+ , K+ , and Cs+ ) in chloride electrolytes on the surface potential, the location of the shear plane, and the capacitance of the Stern layer. We find that the magnitude of the surface potential increases linearly with the hydrated-cation radius. Interpreting our data using the simplest assumptions and most straightforward understanding of Gouy-Chapman-Stern theory reveals a Stern layer whose thickness corresponds to a single layer of water molecules hydrating the silica surface, plus the radius of the hydrated cation. These results subject electrical double-layer theories to direct and falsifiable tests to reveal a physically intuitive and quantitatively verified picture of the Stern layer that is consistent across multiple electrolytes and solution conditions.

  4. Lipid A and immunotherapy.

    PubMed

    Ribi, E; Cantrell, J L; Takayama, K; Qureshi, N; Peterson, J; Ribi, H O

    1984-01-01

    Endotoxin isolated from Re mutants of Salmonella typhimurium or Salmonella minnesota and consisting only of 3-deoxy-D-mannooctulosonic acid (KDO) and lipid A synergistically enhances the ability of mycobacterial cell wall skeleton (CWS) to regress transplantable, line-10 tumor (hepatocellular carcinoma) in syngeneic guinea pigs. Tumor regression is rapid, and systemic tumor immunity concomitantly develops when as little as 50 micrograms of each of these two components is combined and injected intralesionally. Selective removal of KDO from endotoxin yields diphosphoryl lipid A, which retains its toxic properties. Subsequent selective removal of the phosphate moiety at the reducing end of the diphosphoryl lipid A molecule yields nontoxic, monophosphoryl lipid A (determined by lethality for chick embryos). Like the parent endotoxin or toxic diphosphoryl lipid A, monophosphoryl lipid A retains the ability to synergistically enhance the antitumor activity of mycobacterial CWS adjuvant. Both di- and monophosphoryl lipid A contain mixtures of a series of structural analogs. They can be separated chromatographically into single components that differ in number, type, and position of ester-linked fatty acids. Comparison of chromatographic fractions reveals that components of toxic and nontoxic lipid A can be paired according to structure. Each component of the pair has the same molecular structure, with the exception of an additional phosphate group in the toxic component. The toxicity of "lipid A's" liberated from endotoxin by acid hydrolysis appears to be determined by the proportion of di- and monophosphoryl lipid A in the hydrolysis mixture. Structural analogs of monophosphoryl lipid A, which differ in degree of O-acylation and type and distribution of fatty acids, have comparable antitumor activity.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:6382555

  5. Large Eddy Simulations to determine the role of dispersive stresses in the urban canopy layer

    NASA Astrophysics Data System (ADS)

    Christen, Andreas; Giometto, Marco; Parlange, Marc

    2013-04-01

    Urban-scale weather and air pollution forecasting models need to realistically predict conditions in the urban canopy layer (UCL) - the atmosphere in-between buildings where people live and most activities take place. Nevertheless, for performance reasons, forecasting models cannot resolve every detail of the flow field around individual buildings and obstacles in a city. In common urban canopy parameterizations (UCPs), exchange processes between the UCL and the overlying atmosphere - including momentum transfer - are simplified to one-dimensional bulk flow representations, where the time-averaged flow field is also horizontally averaged over a larger spatial subset of the urban canopy. In the spatial averaging process of RANS equations, additional covariance terms arise in the time-averaged momentum balance, called 'dispersive stresses'. Physically, a dispersive stress can be explained as spatial correlation between the mean horizontal flow and mean vertical flow around buildings at a given height layer. Due to lack of knowledge on the role of dispersive fluxes, they are neglected in all current UCPs and transfer formulations. Only limited CFD studies for idealized cubical arrays show that dispersive fluxes are relevant and important to properly describe the overall momentum transfer in those specific rigid canopies. The current contribution determines the role of dispersive stresses to the overall momentum transfer for a more realistic urban canopy by means of large eddy simulation (LES). LES takes into account the unsteadiness that characterizes canopy layer flows, offering indisputably superior performances in predicting momentum exchange with respect to traditional methods, in particular when the effects of canopy elements play a major role. LES also showed to be able to properly represent the flow in areas of strong separation and in wakes, features that are strongly present in urban canopies, where most RANS and URANS models fail due to their under

  6. Separation of Intra- and Extramyocellular Lipid Signals in Proton MR Spectra by Determination of Their Magnetic Field Distribution

    NASA Astrophysics Data System (ADS)

    Steidle, G.; Machann, J.; Claussen, C. D.; Schick, F.

    2002-02-01

    In skeletal musculature intramyocellular (IMCL) and extramyocellular lipids (EMCL) are stored in compartments of different geometry and experience different magnetic field strengths due to geometrical susceptibility effects. The effect is strong enough to-at least partly-separate IMCL and EMCL contributions in 1H MR spectroscopy, despite IMCL and EMCL consisting of the same substances. The assessment of intramyocellular lipid stores in skeletal musculature by 1H MR spectroscopy plays an important role for studying physiological and pathological aspects of lipid metabolism. Therefore, a method using mathematical tools of Fourier analysis is developed to obtain the magnetic field distribution (MFD) from the measured spectra by deconvolution. A reference lipid spectrum is required which was recorded in tibial yellow bone marrow. It is shown that the separation of IMCL contributions can be performed more precisely-compared to other methods-based on the MFD. Examples of deconvolution in model systems elucidate the principle. Applications of the proposed approach on in vivo examinations in m. soleus and m. tibialis anterior are presented. Fitting the IMCL part of the MFD by a Gaussian lineshape with a linewidth kept fixed with respect to the linewidth of creatine and with the assumption of a smooth but not necessarily symmetrical shape for the EMCL part, the only free fit parameter, the amplitude of the IMCL part, is definite and subtraction leads to the EMCL part in the MFD. This procedure is especially justified for the soleus muscle showing a severely asymmetrical distribution which might lead to a marked overestimation of IMCL using common line fitting procedures.

  7. Separation of intra- and extramyocellular lipid signals in proton MR spectra by determination of their magnetic field distribution.

    PubMed

    Steidle, G; Machann, J; Claussen, C D; Schick, F

    2002-02-01

    In skeletal musculature intramyocellular (IMCL) and extramyocellular lipids (EMCL) are stored in compartments of different geometry and experience different magnetic field strengths due to geometrical susceptibility effects. The effect is strong enough to---at least partly---separate IMCL and EMCL contributions in (1)H MR spectroscopy, despite IMCL and EMCL consisting of the same substances. The assessment of intramyocellular lipid stores in skeletal musculature by (1)H MR spectroscopy plays an important role for studying physiological and pathological aspects of lipid metabolism. Therefore, a method using mathematical tools of Fourier analysis is developed to obtain the magnetic field distribution (MFD) from the measured spectra by deconvolution. A reference lipid spectrum is required which was recorded in tibial yellow bone marrow. It is shown that the separation of IMCL contributions can be performed more precisely---compared to other methods---based on the MFD. Examples of deconvolution in model systems elucidate the principle. Applications of the proposed approach on in vivo examinations in m. soleus and m. tibialis anterior are presented. Fitting the IMCL part of the MFD by a Gaussian lineshape with a linewidth kept fixed with respect to the linewidth of creatine and with the assumption of a smooth but not necessarily symmetrical shape for the EMCL part, the only free fit parameter, the amplitude of the IMCL part, is definite and subtraction leads to the EMCL part in the MFD. This procedure is especially justified for the soleus muscle showing a severely asymmetrical distribution which might lead to a marked overestimation of IMCL using common line fitting procedures. PMID:11846580

  8. Preparation of environmental samples for the determination of polycyclic aromatic hydrocarbons by thin-layer chromatography.

    PubMed

    Poole, S K; Dean, T A; Poole, C F

    1987-07-29

    An evaluation of extraction procedures, liquid-liquid distribution systems, Sep-Pak cartridges, liquid-solid chromatography using silica, alumina and chemically modified silica packings (acid-base treated ethylammonium nitrate and picric acid impregnated), macroreticular resins and gel permeation columns for the analysis of polycyclic aromatic hydrocarbons (CPAHs) in environmental samples by thin-layer chromatography is discussed. For particulate samples solvent extraction using a Soxhlet apparatus or ultrasonication was found to be preferable to sublimation and liquid-liquid distribution between hexane and dimethyl sulfoxide followed by silica gel column chromatography was the preferred method for sample clean-up. Using this procedure enabled six PAHs (anthracene, fluoranthene, benz[a]anthracene, perylene, pyrene, and coronene) to be determined quantitatively in urban air particulate, diesel engine exhaust particulate, laboratory ventilator dust, household dust, river water, and tea samples. The PAHs were identified by coincidence of retention between the sample and standards in the same chromatographic system and by adequate agreement with standards for their normalized emission response ratios. The two-point calibration method was used for quantitation. Good agreement for the concentration of PAHs in the air particulate and diesel particulate extracts with published data using gas chromatography-mass spectrometry and high-performance liquid chromatography was found. PMID:2444609

  9. Birth order dependent growth cone segregation determines synaptic layer identity in the Drosophila visual system

    PubMed Central

    Kulkarni, Abhishek; Ertekin, Deniz; Lee, Chi-Hon; Hummel, Thomas

    2016-01-01

    The precise recognition of appropriate synaptic partner neurons is a critical step during neural circuit assembly. However, little is known about the developmental context in which recognition specificity is important to establish synaptic contacts. We show that in the Drosophila visual system, sequential segregation of photoreceptor afferents, reflecting their birth order, lead to differential positioning of their growth cones in the early target region. By combining loss- and gain-of-function analyses we demonstrate that relative differences in the expression of the transcription factor Sequoia regulate R cell growth cone segregation. This initial growth cone positioning is consolidated via cell-adhesion molecule Capricious in R8 axons. Further, we show that the initial growth cone positioning determines synaptic layer selection through proximity-based axon-target interactions. Taken together, we demonstrate that birth order dependent pre-patterning of afferent growth cones is an essential pre-requisite for the identification of synaptic partner neurons during visual map formation in Drosophila. DOI: http://dx.doi.org/10.7554/eLife.13715.001 PMID:26987017

  10. Birth order dependent growth cone segregation determines synaptic layer identity in the Drosophila visual system.

    PubMed

    Kulkarni, Abhishek; Ertekin, Deniz; Lee, Chi-Hon; Hummel, Thomas

    2016-01-01

    The precise recognition of appropriate synaptic partner neurons is a critical step during neural circuit assembly. However, little is known about the developmental context in which recognition specificity is important to establish synaptic contacts. We show that in the Drosophila visual system, sequential segregation of photoreceptor afferents, reflecting their birth order, lead to differential positioning of their growth cones in the early target region. By combining loss- and gain-of-function analyses we demonstrate that relative differences in the expression of the transcription factor Sequoia regulate R cell growth cone segregation. This initial growth cone positioning is consolidated via cell-adhesion molecule Capricious in R8 axons. Further, we show that the initial growth cone positioning determines synaptic layer selection through proximity-based axon-target interactions. Taken together, we demonstrate that birth order dependent pre-patterning of afferent growth cones is an essential pre-requisite for the identification of synaptic partner neurons during visual map formation in Drosophila. PMID:26987017

  11. Role of lipid packing in the activity of phospholipase C-delta1 as determined by hydrostatic pressure measurements.

    PubMed Central

    Rebecchi, M; Bonhomme, M; Scarlata, S

    1999-01-01

    Previous studies with phospholipid monolayers revealed a large decrease in the activity of phosphoinositide-specific phospholipase C-delta(1) (PLC-delta(1)) which catalyses the hydrolysis of PtdIns(4, 5)P(2) as lateral pressure is applied to the membrane. If stress on the membrane is the sole inhibitor of PLC-delta(1) activity, the enzyme must penetrate the membrane surface to engage its substrate. To test the effect on PLC-delta(1) activity of lipid packing in the absence of a directional stress, we examined the effects of increasing hydrostatic pressure on enzymic activity. We find that, in contrast with monolayer studies, increasing lipid packing by hydrostatic pressure does not affect membrane binding and increases enzymic activity by 90% in going from atmospheric pressure to 10(8) Pa (approx. 1000 atm). The increase in activity could be accounted for mainly by electrostriction of water around the multiply-charged product. Our results show that when there is no net stress on the monolayer, lipid packing does not alter PLC-delta(1) activity, possibly because penetration of the enzyme into the membrane surface is shallow. We suggest that, in biological membranes, the activity of this and possibly other interfacial proteins is independent of headgroup packing. PMID:10417319

  12. Vertical aerosol structure and aerosol mixed layer heights determined with scanning shipborne lidars during the TexAQS II study

    NASA Astrophysics Data System (ADS)

    McCarty, B. J.; Senff, C. J.; Tucker, S. C.; Eberhard, W. L.; Marchbanks, R. D.; Machol, J.; Brewer, W. A.

    2007-12-01

    The NOAA Earth Systems Research Laboratory (ESRL) deployed the Ozone Profiling Atmospheric LIDAR (OPAL) on the R/V Ronald H. Brown during the summer of 2006 for the Texas Air Quality Study (TEXAQS II). Calibrated aerosol backscatter profiles were determined from data collected at the 355 nm wavelength using a modified Klett retrieval method. OPAL employs a unique scan sequence that consists of staring at multiple elevation angles between 2 and 90 degrees, which is repeated approx. every 90 sec. Blending the data from the various elevation angles allows to extend the aerosol backscatter profiles down to near the surface (approximately 10 meters ASL), while maintaining a high spatial resolution (5 meters). Successful application of this technique requires the aerosol distribution to be sufficiently horizontally homogeneous over several kilometers. Estimates of aerosol mixed layer height were determined by applying a Haar wavelet transform method to detect the gradient that is often present at the top of the boundary layer. Co-located on the R/V Ronald H. Brown, was NOAA/ESRL's High Resolution Doppler LIDAR (HRDL). Aerosol mixed layer heights were also estimated using the data from the 2 micron Doppler LIDAR. A comparison of the mixed layer heights as determined from each LIDAR's observations was used to choose the height of the layer likely connected with the surface. The vertical structure of aerosols in the lower troposphere, in particular the presence of aerosol layers above the boundary layer, is important in understanding radiative effects of aerosols. We will present aerosol backscatter structure in the lower troposphere encountered during the TexAQS II study as well as a comparison of relative aerosol content in the free troposphere compared to that within the boundary layer.

  13. TRPV1 structures in nanodiscs reveal mechanisms of ligand and lipid action.

    PubMed

    Gao, Yuan; Cao, Erhu; Julius, David; Cheng, Yifan

    2016-06-16

    When integral membrane proteins are visualized in detergents or other artificial systems, an important layer of information is lost regarding lipid interactions and their effects on protein structure. This is especially relevant to proteins for which lipids have both structural and regulatory roles. Here we demonstrate the power of combining electron cryo-microscopy with lipid nanodisc technology to ascertain the structure of the rat TRPV1 ion channel in a native bilayer environment. Using this approach, we determined the locations of annular and regulatory lipids and showed that specific phospholipid interactions enhance binding of a spider toxin to TRPV1 through formation of a tripartite complex. Furthermore, phosphatidylinositol lipids occupy the binding site for capsaicin and other vanilloid ligands, suggesting a mechanism whereby chemical or thermal stimuli elicit channel activation by promoting the release of bioactive lipids from a critical allosteric regulatory site. PMID:27281200

  14. Determination of serum lipid profile in patients with diabetic macular edema that referred to Shahid Beheshti and Ayatollah Rouhani Hospitals, Babol during 2011-2012

    PubMed Central

    Rasoulinejad, Seyed Ahmad; Iri, Habib-Ollah

    2015-01-01

    Background: Diabetes is a common metabolic disorder leading to the development of many complications, among which diabetic retinopathy and macular edema are the most significant. These complications can contribute to blindness if not diagnosed or treated properly, and several studies have been conducted to evaluate the methods for the prevention or slowing down their progression. Therefore, serum lipids, apparently play an effective role in the creation and acceleration of macular edema, we therefore determined the relationship of serum lipid level in patients with diabetic macular edema in the present study. Methods: 180 participants were selected from patients with the definite diagnosis of diabetes referred to the eye clinic of Shahid Beheshti and Ayatollah Rouhani Hospitals of Babol during 2011-2012, the patients with a history of taking lipid –lowering drugs and hypertension were excluded from the study. The study data were provided from the medical records of each patients. SPSS Version 18 was used for analyses. Results: In the present investigation, the mean age of participants was 53.22±with the age range of 18-77 years. Ninety patients with diabetic retinopathy and macular edema were compared with ninety patients with diabetic retinopathy without macular edema (control group) were compared. There was a significant difference in serum cholesterol and LDL-cholesterol between patients and groups (p<0.000). Conclusion: The results of this study indicate that high serum cholesterol and LDL-cholesterol is associated with severity of diabetic retinopathy particularly with macular edema PMID:26221504

  15. Accuracy of Young's Modulus of Thermal Barrier Coating Layer Determined by Bending Resonance of a Multilayered Specimen

    NASA Astrophysics Data System (ADS)

    Waki, Hiroyuki; Takizawa, Kensuke; Kato, Masahiko; Takahashi, Satoru

    2016-04-01

    The Young's modulus of individual layer in thermal barrier coating (TBC) system is an important mechanical property because it allows determining the parameters of materials mechanics in the TBC system. In this study, we investigated the accuracy of the evaluation method for the Young's modulus of a TBC layer according to the first bending resonance of a multilayered specimen comprising a substrate, bond coating, and TBC. First, we derived a closed-form solution for the Young's modulus of the TBC layer using the equation of motion for the bending vibration of a composite beam. The solution for the three-layered model provided the Young's modulus of the TBC layer according to the measured resonance frequency and the known values for the dimensions, mass, and Young's moduli of all the other layers. Next, we analyzed the sensitivity of these input errors to the evaluated Young's modulus and revealed the important inputs for accurate evaluation. Finally, we experimentally confirmed that the Young's modulus of the TBC layer was obtained accurately by the developed method.

  16. An ultrasonic theoretical and experimental approach to determine thickness and wave speed in layered media.

    PubMed

    de Sousa, Ana Valéria Greco; Pereira, Wagner Coelho de Albuquerque; Machado, João Carlos

    2007-02-01

    This work presents an ultrasonic method to characterize the layers of a stratified medium, using independent measurements of wave speed and thickness of each layer. The model, based on geometrical acoustics, includes refraction. Two transducers are used: one active (3.4 MHz) and a hydrophone as a receptor, which is moved laterally through 15 positions. The distance between the transducers and the delay between the echoes, from the interfaces separating the layers, received by them are used to estimate the speed and thickness. Three types of layered phantoms were used: Ph1 made with alcohol/acrylic, Ph2 made with polyvinyl chloride/water/acrylic, and Ph3 made with acrylic/water/polyvinyl chloride. The experimental results for speed of sound and layer thickness presented an experimental mean relative error, for thickness and wave speed, lower than 7.0% and 6.6%, respectively. PMID:17328335

  17. A novel human erythrocyte glycosylphosphatidylinositol (GPI)-anchored glycoprotein ACA. Isolation, purification, primary structure determination, and molecular parameters of its lipid structure.

    PubMed

    Becker Kojić, Zorica A; Terness, Peter

    2002-10-25

    A method has been elaborated to isolate and purify up to homogeneity a novel membrane glycoprotein containing a glycosyl-phosphatidylinositol (GPI) anchor by means of salting out with ammonium sulfate (40-80% saturation), followed by preparative SDS-PAGE, chromatography and acetone precipitation. The preparation obtained was homogeneous upon electrophoresis in the presence of 0.1% SDS after reduction with 2-mercaptoethanol. It is protein-soluble at its isoelectrical point (pH 5.5) with molecular mass of 65,000 daltons. The isolated protein is linked to the membrane via glycosyl-phosphatidylinositol susceptible to cleavage by purified phospholipase C. The hydrophobic portion of the glycolipid membrane anchor of the protein was radiolabeled with the photoactivated reagent 3-(trifluoromethyl)-3-(m-[(125)I]iodophenyl)diazirine and hydrolyzed with glycosyl-phosphatidylinositol-specific phospholipase C, followed by enzymatic deacetylation of the remaining lipid. Thin-layer chromatography showed that the generated radiolabeled fragment migrates with the same mobility as that of variant surface glycoprotein (VSG), obtained in the same manner. In this study we describe a novel erythrocyte membrane GPI-linked protein with the structural feature of an anchor that, in contrast to other GPI-linked erythrocyte proteins, has a non-acetylated inositol ring and diacylglycerol rather than alkyl-acyl glycerol as a lipid tail of the anchor. PMID:12167612

  18. Membrane location of apocytochrome c and cytochrome c determined from lipid-protein spin exchange interactions by continuous wave saturation electron spin resonance.

    PubMed Central

    Snel, M M; Marsh, D

    1994-01-01

    Apocytochrome c derived from horse heart cytochrome c was spin-labeled on the cysteine residue at position 14 or 17 in the N-terminal region of the primary sequence, and cytochrome c from yeast was spin-labeled on the single cysteine residue at sequence position 102 in the C-terminal region. The spin-labeled apocytochrome c and cytochrome c were bound to fluid bilayers composed of different negatively charged phospholipids that also contained phospholipid probes that were spin-labeled either in the headgroup or at different positions in the sn-2 acyl chain. The location of the spin-labeled cysteine residues on the lipid-bound proteins was determined relative to the spin-label positions in the different spin-labeled phospholipids by the influence of spin-spin interactions on the microwave saturation properties of the spin-label electron spin resonance spectra. The enhanced spin relaxation observed in the doubly labeled systems arises from Heisenberg spin exchange, which is determined by the accessibility of the spin-label group on the protein to that on the lipid. It is found that the labeled cysteine groups in horse heart apocytochrome c are located closest to the 14-C atom of the lipid acyl chain when the protein is bound to dimyristoyl- or dioleoyl-phosphatidylglycerol, and to that of the 5-C atom when the protein is bound to a dimyristoylphosphatidylglycerol/dimyristoylphosphatidylcholine (15:85 mol/mol mixture. On binding to dioleoylphosphatidylglycerol, the labeled cysteine residue in yeast cytochrome c is located closest to the phospholipid headgroups but possibly between the polar group region and the 5-C atom of the acyl chains. These data determine the extent to which the different regions of the proteins are able to penetrate negatively charged phospholipid bilayers. Images FIGURE 1 PMID:7948687

  19. Langmuir films study on lipid-containing artificial tears.

    PubMed

    Torrent-Burgués, J

    2016-04-01

    Lipid-containing artificial tears are a type of artificial tears that use lipid components in order to restore the lipid layer of the tear film. One of these components is lecithin which can be applied in spray solutions containing lecithin liposomes. In this work the behavior of three of these commercial tears based on lecithin, Innoxa, Opticalm and Optrex, are studied using the Langmuir technique. The obtained isotherms are presented, discussed and compared. This technique seems useful in order to see the film behavior of the lipid components of these tears and determine some important parameters such as fluidity and extension at the air-water interface, and allows us to discern differences between these commercial tears. Innoxa and Optrex tears are more similar to each other than to Opticalm tears. Opticalm presents more fluidity, probably due to the presence of more insaturations in the fatty acid chains of the phospholipids of the lecithin used in fabrication. PMID:26764100

  20. Cyanogenic Lipids

    PubMed Central

    Selmar, Dirk; Grocholewski, Sabine; Seigler, David S.

    1990-01-01

    Large amounts of cyanogenic lipids (esters of 1 cyano-2-methylprop-2-ene-1-ol with C:20 fatty acids) are stored in the seeds of Ungnadia speciosa. During seedling development, these lipids are completely consumed without liberation of free HCN to the atmosphere. At the same time, cyanogenic glycosides are synthesized, but the total amount is much lower (about 26%) than the quantity of cyanogenic lipids formerly present in the seeds. This large decrease in the total content of cyanogens (HCN-potential) demonstrates that at least 74% of cyanogenic lipids are converted to noncyanogenic compounds. Whether the newly synthesized cyanogenic glycosides are derived directly from cyanogenic lipids or produced by de novo synthesis is still unknown. Based on the utilization of cyanogenic lipids for the synthesis of noncyanogenic compounds, it is concluded that these cyanogens serve as storage for reduced nitrogen. The ecophysiological significance of cyanolipids based on multifunctional aspects is discussed. PMID:16667514

  1. INAA determination of major and trace elements in loess, paleosol and precipitation layers in a pleistocene Loess Section, China

    USGS Publications Warehouse

    Tian, J.; Chou, C.-L.; Ehmann, W.D.

    1987-01-01

    Instrumental neutron activation analysis was used for the determination of 31 major and trace elements in 32 samples from the Xinji Loess Section, Shaanxi Province, China. Interferences, including those from uranium fission products, were evaluated and corrections applied where necessary. The 39.7-meter deep section comprises of Lishi Loess of the middle Pleistocene (Q2) and Malan Loess of the late Pleistocene (Q3). The section is characterized by the presence of 5 layers of paleosol, and each paleosol is underlain by a precipitation layer. When the elemental abundances are converted to a carbonate-free basis, there is little compositional difference among the carbonate-free fractions of loess, paleosol and precipitation layers. This indicates that dissolution of carbonate minerals by downward-moving surface water was an important process in paleosol formation while other minerals were not severely weathered and elemental fractionation was minimal. The parent materials of the paleosol and precipitation layers closely resemble the loess layers in their elemental abundances, which suggests that all layers in the section have a compositionally similar source. ?? 1987 Akade??miai Kiado??.

  2. Acyl-lipid metabolism.

    PubMed

    Li-Beisson, Yonghua; Shorrosh, Basil; Beisson, Fred; Andersson, Mats X; Arondel, Vincent; Bates, Philip D; Baud, Sébastien; Bird, David; Debono, Allan; Durrett, Timothy P; Franke, Rochus B; Graham, Ian A; Katayama, Kenta; Kelly, Amélie A; Larson, Tony; Markham, Jonathan E; Miquel, Martine; Molina, Isabel; Nishida, Ikuo; Rowland, Owen; Samuels, Lacey; Schmid, Katherine M; Wada, Hajime; Welti, Ruth; Xu, Changcheng; Zallot, Rémi; Ohlrogge, John

    2013-01-01

    Acyl lipids in Arabidopsis and all other plants have a myriad of diverse functions. These include providing the core diffusion barrier of the membranes that separates cells and subcellular organelles. This function alone involves more than 10 membrane lipid classes, including the phospholipids, galactolipids, and sphingolipids, and within each class the variations in acyl chain composition expand the number of structures to several hundred possible molecular species. Acyl lipids in the form of triacylglycerol account for 35% of the weight of Arabidopsis seeds and represent their major form of carbon and energy storage. A layer of cutin and cuticular waxes that restricts the loss of water and provides protection from invasions by pathogens and other stresses covers the entire aerial surface of Arabidopsis. Similar functions are provided by suberin and its associated waxes that are localized in roots, seed coats, and abscission zones and are produced in response to wounding. This chapter focuses on the metabolic pathways that are associated with the biosynthesis and degradation of the acyl lipids mentioned above. These pathways, enzymes, and genes are also presented in detail in an associated website (ARALIP: http://aralip.plantbiology.msu.edu/). Protocols and methods used for analysis of Arabidopsis lipids are provided. Finally, a detailed summary of the composition of Arabidopsis lipids is provided in three figures and 15 tables. PMID:23505340

  3. Acyl-lipid metabolism.

    PubMed

    Li-Beisson, Yonghua; Shorrosh, Basil; Beisson, Fred; Andersson, Mats X; Arondel, Vincent; Bates, Philip D; Baud, Sébastien; Bird, David; Debono, Allan; Durrett, Timothy P; Franke, Rochus B; Graham, Ian A; Katayama, Kenta; Kelly, Amélie A; Larson, Tony; Markham, Jonathan E; Miquel, Martine; Molina, Isabel; Nishida, Ikuo; Rowland, Owen; Samuels, Lacey; Schmid, Katherine M; Wada, Hajime; Welti, Ruth; Xu, Changcheng; Zallot, Rémi; Ohlrogge, John

    2010-01-01

    Acyl lipids in Arabidopsis and all other plants have a myriad of diverse functions. These include providing the core diffusion barrier of the membranes that separates cells and subcellular organelles. This function alone involves more than 10 membrane lipid classes, including the phospholipids, galactolipids, and sphingolipids, and within each class the variations in acyl chain composition expand the number of structures to several hundred possible molecular species. Acyl lipids in the form of triacylglycerol account for 35% of the weight of Arabidopsis seeds and represent their major form of carbon and energy storage. A layer of cutin and cuticular waxes that restricts the loss of water and provides protection from invasions by pathogens and other stresses covers the entire aerial surface of Arabidopsis. Similar functions are provided by suberin and its associated waxes that are localized in roots, seed coats, and abscission zones and are produced in response to wounding. This chapter focuses on the metabolic pathways that are associated with the biosynthesis and degradation of the acyl lipids mentioned above. These pathways, enzymes, and genes are also presented in detail in an associated website (ARALIP: http://aralip.plantbiology.msu.edu/). Protocols and methods used for analysis of Arabidopsis lipids are provided. Finally, a detailed summary of the composition of Arabidopsis lipids is provided in three figures and 15 tables. PMID:22303259

  4. Acyl-Lipid Metabolism

    PubMed Central

    Li-Beisson, Yonghua; Shorrosh, Basil; Beisson, Fred; Andersson, Mats X.; Arondel, Vincent; Bates, Philip D.; Baud, Sébastien; Bird, David; DeBono, Allan; Durrett, Timothy P.; Franke, Rochus B.; Graham, Ian A.; Katayama, Kenta; Kelly, Amélie A.; Larson, Tony; Markham, Jonathan E.; Miquel, Martine; Molina, Isabel; Nishida, Ikuo; Rowland, Owen; Samuels, Lacey; Schmid, Katherine M.; Wada, Hajime; Welti, Ruth; Xu, Changcheng; Zallot, Rémi; Ohlrogge, John

    2010-01-01

    Acyl lipids in Arabidopsis and all other plants have a myriad of diverse functions. These include providing the core diffusion barrier of the membranes that separates cells and subcellular organelles. This function alone involves more than 10 membrane lipid classes, including the phospholipids, galactolipids, and sphingolipids, and within each class the variations in acyl chain composition expand the number of structures to several hundred possible molecular species. Acyl lipids in the form of triacylglycerol account for 35% of the weight of Arabidopsis seeds and represent their major form of carbon and energy storage. A layer of cutin and cuticular waxes that restricts the loss of water and provides protection from invasions by pathogens and other stresses covers the entire aerial surface of Arabidopsis. Similar functions are provided by suberin and its associated waxes that are localized in roots, seed coats, and abscission zones and are produced in response to wounding. This chapter focuses on the metabolic pathways that are associated with the biosynthesis and degradation of the acyl lipids mentioned above. These pathways, enzymes, and genes are also presented in detail in an associated website (ARALIP: http://aralip.plantbiology.msu.edu/). Protocols and methods used for analysis of Arabidopsis lipids are provided. Finally, a detailed summary of the composition of Arabidopsis lipids is provided in three figures and 15 tables. PMID:22303259

  5. Acyl-Lipid Metabolism

    PubMed Central

    Li-Beisson, Yonghua; Shorrosh, Basil; Beisson, Fred; Andersson, Mats X.; Arondel, Vincent; Bates, Philip D.; Baud, Sébastien; Bird, David; DeBono, Allan; Durrett, Timothy P.; Franke, Rochus B.; Graham, Ian A.; Katayama, Kenta; Kelly, Amélie A.; Larson, Tony; Markham, Jonathan E.; Miquel, Martine; Molina, Isabel; Nishida, Ikuo; Rowland, Owen; Samuels, Lacey; Schmid, Katherine M.; Wada, Hajime; Welti, Ruth; Xu, Changcheng; Zallot, Rémi; Ohlrogge, John

    2013-01-01

    Acyl lipids in Arabidopsis and all other plants have a myriad of diverse functions. These include providing the core diffusion barrier of the membranes that separates cells and subcellular organelles. This function alone involves more than 10 membrane lipid classes, including the phospholipids, galactolipids, and sphingolipids, and within each class the variations in acyl chain composition expand the number of structures to several hundred possible molecular species. Acyl lipids in the form of triacylglycerol account for 35% of the weight of Arabidopsis seeds and represent their major form of carbon and energy storage. A layer of cutin and cuticular waxes that restricts the loss of water and provides protection from invasions by pathogens and other stresses covers the entire aerial surface of Arabidopsis. Similar functions are provided by suberin and its associated waxes that are localized in roots, seed coats, and abscission zones and are produced in response to wounding. This chapter focuses on the metabolic pathways that are associated with the biosynthesis and degradation of the acyl lipids mentioned above. These pathways, enzymes, and genes are also presented in detail in an associated website (ARALIP: http://aralip.plantbiology.msu.edu/). Protocols and methods used for analysis of Arabidopsis lipids are provided. Finally, a detailed summary of the composition of Arabidopsis lipids is provided in three figures and 15 tables. PMID:23505340

  6. Expanding lipid proxies to the next dimension: Developing methods for determination of oxygen isotope ratios in plant waxes

    NASA Astrophysics Data System (ADS)

    Maxwell, T.; Silva, L. C. R.; Horwath, W. R.

    2014-12-01

    We seek to understand the δ18O signal of n-alkanols, a biosynthetically similar compound group to the highly studied n-alkanes. Alkanols of >24 carbons are produced at the leaf level, incorporating a transpiration enriched oxygen and hydrogen signal. The use of δ18O as a proxy is of great interest because of the more simplistic biosynthetic sourcing of oxygen in lipids. Complete equilibration of organic and water bound oxygen atoms is achieved in the Calvin cycle (all oxygen atoms are at some point in an exchangeable carbonyl group). This leads to a uniform signal among oxygen atoms incorporated through photosynthesis. Although it is analytically useful, the larger abundance of hydrogen isotopes in the same molecule leads to a more ambiguous signal, especially when integrating through soils and sediments. This study stems from recent work in our lab, which has shown significant relationships between an applied evapotranspiration deficit and δ18O in bulk lipid (hexane) extracts of plant material. While it is exciting that bulk lipids show this relationship, it is critical to first demonstrate that the isotopic signal is stable in order to use the signal from preserved alkanols as an integrator in soils and sediments. In this experiment, we show for the first time that a series of n-alkanols do not exchange oxygen with environmental water. Moving forward we are developing methods to address the analytical challenges of measuring oxygen isotope ratios of these compounds. Once this is overcome, we will be able to measure δD, δ18O, and δ13C from a single compound in a homogenized sample. The end result will be an improvement in the ability to interpret changes in field scale evapotranspiration, moving from a 2 dimensional (δD and δ13C only) to 3 dimensional (i.e. the addition of δ18O) model. This will apply to both modern and paleohydrologic relationships, improving our ability to reconstruct and predict the impacts of water balance variability across

  7. Limits of accuracy obtainable in the direct determination by fluorimetry of fluorescent whitening agents on thin layer chromatograms.

    PubMed

    Anders, G

    1975-01-01

    The quantitative direct determination of fluorescent whitening agents (FWAs) by thin layer chromatography involves limits of detection of 0.001 to 0.0005 mug. Visual assessment is about ten to a hundred times less sensitive than photometric measurement on thin layer chromatograms. The standard deviations in 10 measurements of two substances with different degrees of light sensitivity for a single measurement with a limit of detection of the order of 0.005 mug were about +/-13% to 44%. In the higher concentrations normally used (0.5 mug), the standard deviations were only +/-5% for both substances. PMID:1064526

  8. Understanding and Analyzing Meibomian Lipids-A Review

    PubMed Central

    Butovich, Igor A.; Ham, Bryan M.

    2009-01-01

    Purpose This review is intended to bring to the informed reader the current state of knowledge about meibomian lipids and the art for analyzing them. Methods At the forefront of any endeavor, there are controversies, and these, along with future directions in the field, are brought to the reader's attention. Results Function and anatomy of meibomian glands are briefly covered, giving insight into possible mechanisms for secretory controls. Anatomically, some anomalies in meibomian gland distribution of different species, such as whales versus dolphins, are presented, and, for the first time, the structure of the meibomian glands in a selection of marsupials is presented. In attempting to make the literature more accessible, lipid structure and nomenclature are described, and these structures are related to their possible effects on the physicochemical properties of meibomian lipids. The advantages and disadvantages of various collection and storage techniques are described, as well as how gas chromatography and combined HPLC and mass spectrometry coupled with fragmentation are currently enabling us to determine the nature of the lipids in very small samples. Conclusions This review extends to discussing the lipids in tears (as opposed to meibomian gland lipids) and briefly highlights new thoughts about the interactions between proteins of the tear film and meibomian lipids. A model that includes proteins in the outer layer of the tear film is also presented. This model is currently being critically analyzed by the ocular community. It concludes briefly by highlighting possible further areas of research in this area. PMID:18568877

  9. Symbiodinium Genotypic and Environmental Controls on Lipids in Reef Building Corals

    PubMed Central

    Cooper, Timothy F.; Lai, Michael; Ulstrup, Karin E.; Saunders, Sandra M.; Flematti, Gavin R.; Radford, Ben; van Oppen, Madeleine J. H.

    2011-01-01

    Background Lipids in reef building corals can be divided into two classes; non-polar storage lipids, e.g. wax esters and triglycerides, and polar structural lipids, e.g. phospholipids and cholesterol. Differences among algal endosymbiont types are known to have important influences on processes including growth and the photobiology of scleractinian corals yet very little is known about the role of symbiont types on lipid energy reserves. Methodology/Principal Findings The ratio of storage lipid and structural lipid fractions of Scott Reef corals were determined by thin layer chromatography. The lipid fraction ratio varied with depth and depended on symbiont type harboured by two corals (Seriatopora hystrix and Pachyseris speciosa). S. hystrix colonies associated with Symbiodinium C1 or C1/C# at deep depths (>23 m) had lower lipid fraction ratios (i.e. approximately equal parts of storage and structural lipids) than those with Symbiodinium D1 in shallow depths (<23 m), which had higher lipid fraction ratios (i.e. approximately double amounts of storage relative to structural lipid). Further, there was a non-linear relationship between the lipid fraction ratio and depth for S. hystrix with a modal peak at ∼23 m coinciding with the same depth as the shift from clade D to C types. In contrast, the proportional relationship between the lipid fraction ratio and depth for P. speciosa, which exhibited high specificity for Symbiodinium C3 like across the depth gradient, was indicative of greater amounts of storage lipids contained in the deep colonies. Conclusions/Significance This study has demonstrated that Symbiodinium exert significant controls over the quality of coral energy reserves over a large-scale depth gradient. We conclude that the competitive advantages and metabolic costs that arise from flexible associations with divergent symbiont types are offset by energetic trade-offs for the coral host. PMID:21637826

  10. Aliphatic chain length by isotropic mixing (ALCHIM): determining composition of complex lipid samples by 1H NMR spectroscopy

    PubMed Central

    Yi, Ruiyang; Volden, Paul A.; Conzen, Suzanne D.

    2015-01-01

    Quantifying the amounts and types of lipids present in mixtures is important in fields as diverse as medicine, food science, and biochemistry. Nuclear magnetic resonance (NMR) spectroscopy can quantify the total amounts of saturated and unsaturated fatty acids in mixtures, but identifying the length of saturated fatty acid or the position of unsaturation by NMR is a daunting challenge. We have developed an NMR technique, aliphatic chain length by isotropic mixing, to address this problem. Using a selective total correlation spectroscopy technique to excite and transfer magnetization from a resolved resonance, we demonstrate that the time dependence of this transfer to another resolved site depends linearly on the number of aliphatic carbons separating the two sites. This technique is applied to complex natural mixtures allowing the identification and quantification of the constituent fatty acids. The method has been applied to whole adipocytes demonstrating that it will be of great use in studies of whole tissues. PMID:24831341

  11. Contribution of various lipid profile parameters in determining creatine kinase-MB levels in unstable angina patients

    PubMed Central

    Bagale, Kiran R; Ingle, Avinash S; Choudhary, Rajeev

    2016-01-01

    Context: In India, the correlation of severity of minor myocardial damage with dyslipidemia has rarely been studied in patients of unstable angina (UA). Dyslipidemia is proven to be a major risk factor for developing acute coronary syndrome (ACS) but still there is doubt about the type of lipoproteins involved in causing minor myocardial damage occurring in UA patients of ACS. Aims: The aim of our study was to find out the contribution of various types of lipoproteins to predict the severity of minor myocardial damage occurring in the patients of UA. Settings and Design: Correlation design was used for the study. A single group of individuals was selected. Data were collected on dependent variable creatine kinase-MB (CK-MB) and independent variables (lipid profile parameters). Subjects and Methods: The study comprised fifty patients admitted in cardiac care unit with typical history of UA with electrocardiogram showing no ST-segment elevation. The severity of myocardial damage was assessed from on admission CK-MB levels. The lipid profile was estimated from fasting blood samples of all the patients. Statistical Analysis Used: For the purpose of the study, Pearson correlation and multiple linear regression analysis methods were applied. Results: The triacylglycerol (TAG), very-low-density lipoprotein (VLDL), total cholesterol/high-density lipoprotein (TC/HDL) showed significant positive correlation whereas HDL was negatively correlating with CK-MB levels. Conclusions: The TAG, VLDL, and TC/HDL were found to be significantly affecting the severity of myocardial damage in the patients of UA. PMID:27127739

  12. Method to determine the optimal layer number for the quadrupolar fiber coil

    NASA Astrophysics Data System (ADS)

    Gao, Zhongxing; Zhang, Yonggang; Gao, Wei

    2014-08-01

    For a high precision interferometric fiber optic gyroscope (IFOG) under temperature control, a short start-up time and small temperature drift are important for its applications. The start-up time and the temperature drift of IFOG with the same fiber length but with a different fiber coil layer number are investigated and compared. Simulation by finite difference time domain method is done to illustrate the existence of optimal layer number for the fiber coil wound by the quadrupolar method. Theoretical analysis is then provided and a closed-form formulation is given to calculate the optimal layer number of the fiber coil, which can effectively reduce both the start-up time and temperature drift of IFOG. Our study is meaningful in improving the thermal performance of the fiber coil.

  13. Large-scale recrystallization of the S-layer of Bacillus coagulans E38-66 at the air/water interface and on lipid films.

    PubMed Central

    Pum, D; Weinhandl, M; Hödl, C; Sleytr, U B

    1993-01-01

    S-layer protein isolated from Bacillus coagulans E38-66 could be recrystallized into large-scale coherent monolayers at an air/water interface and on phospholipid films spread on a Langmuir-Blodgett trough. Because of the asymmetry in the physiochemical surface properties of the S-layer protein, the subunits were associated with their more hydrophobic outer face with the air/water interface and oriented with their negatively charged inner face to the zwitterionic head groups of the dipalmitoylphosphatidylcholine and dipalmitoylphosphatidylethanolamine (DPPE) monolayer films. The dynamic crystal growth at both types of interfaces was first initiated at several distant nucleation points. The individual monocrystalline areas grew isotropically in all directions until the front edge of neighboring crystals was met. The recrystallized S-layer protein and the S-layer-DPPE layer could be chemically cross-linked from the subphase with glutaraldehyde. Images PMID:8478338

  14. Forming lipid bilayer membrane arrays on micropatterned polyelectrolyte film surfaces.

    PubMed

    Zhang, Ying; Wang, Lei; Wang, Xuejing; Qi, Guodong; Han, Xiaojun

    2013-07-01

    A novel method of forming lipid bilayer membrane arrays on micropatterned polyelectrolyte film surfaces is introduced. Polyelectrolyte films were fabricated by the layer-by-layer technique on a silicon oxide surface modified with a 3-aminopropyltriethoxysilane (APTES) monolayer. The surface pK(a) value of the APTES monolayer was determined by cyclic voltammetry to be approximately 5.61, on the basis of which a pH value of 2.0 was chosen for layer-by-layer assembly. Micropatterned polyelectrolyte films were obtained by deep-UV (254 nm) photolysis though a mask. Absorbed fluorescent latex beads were used to visualize the patterned surfaces. Lipid bilayer arrays were fabricated on the micropatterned surfaces by immersing the patterned substrates into a solution containing egg phosphatidylcholine vesicles. Fluorescence recovery after photobleaching studies yielded a lateral diffusion coefficient for probe molecules of 1.31±0.17 μm(2) s(-1) in the bilayer region, and migration of the lipid NBD PE in bilayer lipid membrane arrays was observed in an electric field. PMID:23695862

  15. Milk lipids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Milk fat conveys a number of desirable qualities to food, and various lipid components contribute to human nutrition and health. Over 96% of milk lipids consist of triacylglycerols, which contain a variety of fatty acids. Di- and monoacylglycerols, free fatty acids, sterols, and phospho-, glyco-,...

  16. Synthesis of Lipidated Proteins.

    PubMed

    Mejuch, Tom; Waldmann, Herbert

    2016-08-17

    Protein lipidation is one of the major post-translational modifications (PTM) of proteins. The attachment of the lipid moiety frequently determines the localization and the function of the lipoproteins. Lipidated proteins participate in many essential biological processes in eukaryotic cells, including vesicular trafficking, signal transduction, and regulation of the immune response. Malfunction of these cellular processes usually leads to various diseases such as cancer. Understanding the mechanism of cellular signaling and identifying the protein-protein and protein-lipid interactions in which the lipoproteins are involved is a crucial task. To achieve these goals, fully functional lipidated proteins are required. However, access to lipoproteins by means of standard expression is often rather limited. Therefore, semisynthetic methods, involving the synthesis of lipidated peptides and their subsequent chemoselective ligation to yield full-length lipoproteins, were developed. In this Review we summarize the commonly used methods for lipoprotein synthesis and the development of the corresponding chemoselective ligation techniques. Several key studies involving full-length semisynthetic lipidated Ras, Rheb, and LC3 proteins are presented. PMID:27444727

  17. Changes of crop rotation in Iowa determined from the USDA-NASS cropland data layer product

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Crop rotation is one of the important decisions made independently by numerous farm managers, and is a critical variable in models of crop growth and soil carbon. By combining multiple years (2001-2009) of the USDA National Agricultural Statistics Service (NASS) cropland data layer (CDL), it is pos...

  18. Determination of the parameters of a holographic layer from its spectral characteristics

    NASA Astrophysics Data System (ADS)

    Kraiskii, A. A.; Kraiskii, A. V.

    2016-06-01

    Methods for estimating the main parameters of holographic sensors (refractive index modulation depth and hologram thickness) from transmission spectra in the absence of absorption and light scattering are discussed. The consideration is performed for layers oriented parallel to the holographic layer surface under normal light incidence. Direct numerical solution of the problem of light propagation in a periodic nonabsorbing medium is used to study the reflection and transmission spectra of the holographic layer in a wide range of variation in its thickness and the refractive index modulation depth. A classification of the reflection regimes from the holographic layer is proposed (from weak reflection to the photonic crystal regime). A comparison with the results obtained by the coupled-wave analysis is performed, and the limitations of this method at a significant spectral detuning from resonance and under conditions of strong reflection are revealed. It is shown that the main hologram parameters can be estimated from the experimental transmission spectrum of the phase hologram (in the case of strong reflection) based on the spectral dip parameters.

  19. EFFECT OF TEMPERATURE ON THE C ISOTOPIC VALUE OF MICROBIAL LIPIDS APPLIED TO DETERMINE C USAGE IN MICROBIAL COMMUNITIES

    EPA Science Inventory

    The combination of compound specific stable isotopic analysis with phospholipid fatty acid (PLFAS) analysis is useful in determining the source of organic carbon used by groups of a microbial community. Determination of the effect of certain environmental parameters is important ...

  20. Stacking sequence determines Raman intensities of observed interlayer shear modes in 2D layered materials - A general bond polarizability model

    NASA Astrophysics Data System (ADS)

    Luo, Xin; Lu, Xin; Cong, Chunxiao; Yu, Ting; Xiong, Qihua; Ying Quek, Su

    2015-10-01

    2D layered materials have recently attracted tremendous interest due to their fascinating properties and potential applications. The interlayer interactions are much weaker than the intralayer bonds, allowing the as-synthesized materials to exhibit different stacking sequences, leading to different physical properties. Here, we show that regardless of the space group of the 2D materials, the Raman frequencies of the interlayer shear modes observed under the typical configuration blue shift for AB stacked materials, and red shift for ABC stacked materials, as the number of layers increases. Our predictions are made using an intuitive bond polarizability model which shows that stacking sequence plays a key role in determining which interlayer shear modes lead to the largest change in polarizability (Raman intensity); the modes with the largest Raman intensity determining the frequency trends. We present direct evidence for these conclusions by studying the Raman modes in few layer graphene, MoS2, MoSe2, WSe2 and Bi2Se3, using both first principles calculations and Raman spectroscopy. This study sheds light on the influence of stacking sequence on the Raman intensities of intrinsic interlayer modes in 2D layered materials in general, and leads to a practical way of identifying the stacking sequence in these materials.

  1. Summary of experimentally determined facts concerning the behavior of the boundary layer and performance of boundary layer measurements. [considering sailing flight

    NASA Technical Reports Server (NTRS)

    Vanness, W.

    1978-01-01

    A summary report of boundary layer studies is presented. Preliminary results of experimental measurements show that: (1) A very thin layer (approximately 0.4 mm) of the boundary layer seems to be accelerated; (2) the static pressure of the outer flow does not remain exactly constant through the boundary layer; and (3) an oncoming boundary layer which is already turbulent at the suction point can again become laminar behind this point without being completely sucked off.

  2. Isolation and Characterization of Chicken Yolk Vitelline Membrane Lipids Using Eggs Enriched With Conjugated Linoleic Acid.

    PubMed

    Shinn, Sara Elizabeth; Liyanage, Rohana; Lay, Jackson O; Proctor, Andrew

    2016-06-01

    The vitelline membrane (VM) encloses the chicken egg yolk, separating it from albumen. The VM weakens during storage, and dietary lipid modification significantly affects its strength. However, no studies have characterize the fatty acyl residue (FA) composition of the VM, and reports of VM isolation and quantified lipid content are inconsistent. Therefore, the objectives of this study were: (1) to develop a washing and isolation method that removes residual yolk from VM without damage; (2) to determine the FA and lipid composition of CLA-rich egg yolk VM, relative to controls; (3) to determine the effect of 20 days of refrigeration on VM FA and lipid composition. To determine VM FA and lipid composition, 36 hens received either a corn-soybean meal-based control diet ("Control"), or the Control supplemented with either 10 % soy oil ("Soy control"), or 10 % CLA-rich soy oil ("CLA") for 30 days. VM were analyzed the day of collection ("fresh"), or after 20 days of refrigeration ("refrigerated"). There were no differences in FA compositions of fresh and refrigerated membranes within a treatment. CLA-rich yolk VM contains CLA, greater SFA, and significantly greater DHA relative to controls. Direct MALDI-TOF-MS identified 15 phosphatidylcholines, three phosphatidylethanolamines, one sphingomyelin, and 15 triacylglycerols in VM. Lipid species that showed significant differences among egg types included nine phosphatidylcholines and six triacylglycerols. MALDI analysis indicated significant differences in nine lipid classes on the VM inner layer. After refrigeration, five lipid classes on the inner layer and seven lipid classes on the outer layer had statistically significant differences among VM types. PMID:27108035

  3. Multilayer Films Electrodes Consisted of Cashew Gum and Polyaniline Assembled by the Layer-by-Layer Technique: Electrochemical Characterization and Its Use for Dopamine Determination

    PubMed Central

    Barros, Sergio Bitencourt Araújo; Leite, Cleide Maria da Silva; de Brito, Ana Cristina Facundo; Dos Santos Júnior, José Ribeiro; Zucolotto, Valtencir; Eiras, Carla

    2012-01-01

    We take advantage of polyelectrolyte feature exhibited by natural cashew gum (Anacardium occidentale L.) (CG), found in northeast Brazil, to employ it in the formation of electroactive nanocomposites prepared by layer-by-layer (LbL) technique. We used polyaniline unmodified (PANI) or modified with phosphonic acid (PA), PANI-PA as cationic polyelectrolyte. On the other hand, the CG or polyvinyl sulfonic (PVS) acids were used as anionic polyelectrolytes. The films were prepared with PANI or PANI-PA intercalated with CG or with PVS alternately resulting in four films with different sequences: PANI/CG PANI-PA/CG, PANI/PVS and PANI-PA/PVS, respectively. Analysis by cyclic voltammetry (CV) of the films showed that the presence of gum increases the stability of the films in acidic medium. The performance of the modified electrode of PANI-PA/CG was evaluated in electro analytical determination of dopamine (DA). The tests showed great sensitivity of the film for this analyte that was detected at 10−5 mol L−1. PMID:22505924

  4. Determination of fluoroquinolone antibiotics through the fluorescent response of Eu(III) based nanoparticles fabricated by layer-by-layer technique.

    PubMed

    Davydov, Nikolay; Zairov, Rustem; Mustafina, Asiya; Syakayev, Viktor; Tatarinov, Dmitry; Mironov, Vladimir; Eremin, Sergei; Konovalov, Alexander; Mustafin, Marat

    2013-06-19

    The present work introduces the determination of fluoroquinolone antibiotics (FQs) in aqueous solutions through the fluorescent response of Eu(TTA)3 and [Eu(TTA)(3)1] (TTA(-) and 1 are thenoyltrifluoroacetonate and phosphine oxide derivative) complexes encapsulated into the polyelectrolyte capsules fabricated through layer-by-layer deposition of poly(sodium 4-styrenesulfonate) (PSS) and polyethyleneimine (PEI). The variation of luminescent core, polyelectrolyte deposition and concentration conditions reveals two modes of fluorescent response on FQs of diverse structure namely the sensitization and quenching of Eu(III) centered luminescence. The obtained regularities reveal the ternary complex formation and the ligand exchange occurring at the interface of polyelectrolyte coated [Eu(TTA)(3)1] based colloids as the reasons of the diverse fluorescent response of Eu(III) centered luminescence on FQs. The factors affecting the fluorescent response have been revealed, which are: the content of luminescent core, the mode of polyelectrolyte deposition, concentration and structure of FQs. The discrimination of moxifloxacin and lomefloxacin from levofloxacin, ofloxacin, difloxacin, perfloxacin through the quenching of Eu(III) luminescence in PSS-[Eu(TTA)(3)1] colloids has been revealed. PMID:23746410

  5. [Trigonelline in coffee. I. Comparison of thin layer chromatography with high-performance liquid chromatography. Simultaneous determination of caffeine].

    PubMed

    Stennert, A; Maier, H G

    1993-05-01

    Determination of trigonelline in several green and roasted coffees by thin-layer (TLC) and high-performance liquid chromatography (HPLC) were compared. Using TLC, two methods of detection were also compared. In addition, caffeine could be determined using HPLC. The determinations were each made with several variations of extraction and clean-up. Recoveries, variation coefficients and detection limits are listed. The most suitable method was HPLC in connection with hot water extraction. Only water is required as the mobile phase. The values for precision are in most cases better than (trigonelline) or similar to (caffeine) those reported in the literature. The determination of trigonelline by TLC, followed by extraction and photometry, is possible with a similar precision, but the simultaneous determination of caffeine was not tested. PMID:8511975

  6. Direct determination of fluorescent whitening agents by absorption measurement in situ on thin layer chromatograms.

    PubMed

    Theidel, H

    1975-01-01

    The measuring technique for the chromatogram spectrophotometer (Zeiss) to determine the reflectance curves, the analysis according to the Kubelka-Munck function, and the basic outlines of the quantitative determination of stilbene fluorescent whitening agents (FWAs) are explained. PMID:1064527

  7. Large-area few-layered graphene film determination by multispectral imaging microscopy.

    PubMed

    Wang, Hsiang-Chen; Huang, Shih-Wei; Yang, Jhe-Ming; Wu, Guan-Huang; Hsieh, Ya-Ping; Feng, Shih-Wei; Lee, Min Kai; Kuo, Chie-Tong

    2015-05-21

    A multispectral imaging method for the rapid and accurate identification of few-layered graphene using optical images is proposed. Commonly rapid identification relies on optical interference effects which limits the choice of substrates and light sources. Our method is based on the comparison of spectral characteristics with principle components from a database which is populated by correlation of micro-Raman registration, spectral characteristics, and optical microscopy. Using this approach the thickness and extent of different graphene layers can be distinguished without the contribution of the optical interference effects and allows characterization of graphene on glass substrates. The high achievable resolution, easy implementation and large scale make this approach suitable for the in-line metrology of industrial graphene production. PMID:25921320

  8. Nonlinear physical segmentation algorithm for determining the layer boundary from lidar signal.

    PubMed

    Mao, Feiyue; Li, Jun; Li, Chen; Gong, Wei; Min, Qilong; Wang, Wei

    2015-11-30

    Layer boundary (base and top) detection is a basic problem in lidar data processing, the results of which are used as inputs of optical properties retrieval. However, traditional algorithms not only require manual intervention but also rely heavily on the signal-to-noise ratio. Therefore, we propose a robust and automatic algorithm for layer detection based on a novel algorithm for lidar signal segmentation and representation. Our algorithm is based on the lidar equation and avoids most of the limitations of the traditional algorithms. Testing of the simulated and real signals shows that the algorithm is able to position the base and top accurately even with a low signal to noise ratio. Furthermore, the results of the classification are accurate and satisfactory. The experimental results confirm that our algorithm can be used for automatic detection, retrieval, and analysis of lidar data sets. PMID:26698806

  9. NMR as a method to determine water content changes in the upper soil layer during evaporation

    NASA Astrophysics Data System (ADS)

    Merz, Steffen; Pohlmeier, Andreas; van Dusschoten, Dagmar; Vereecken, Harry

    2013-04-01

    Water exchange between bare soil and atmosphere is controlled by evaporation. In the topmost soil layer moisture content and hydraulic conductivity may change strongly and capillary film flow (stage I) from saturated regions to the surface discontinues. Evaporation is now mainly driven by vapor diffusion through a dry layer (stage II). Water vaporizes in the unsaturated zone inside the soil what strongly reduces the evaporation rate and also soil surface temperature to a considerable amount. The dynamics of the transition from stage I to stage II as well as film flow and vapor diffusion at low water contents have received little attention. In this study we investigated water content changes in the uppermost soil layer with high spatial resolution using nuclear magnetic resonance (NMR). NMR is a feasible noninvasive method where the received signal of hydrogen protons allows conclusions on moisture and pore size distribution. The overall aim is to apply a mobile nuclear magnetic resonance surface sensor (NMR-MOUSE) directly for field measurements. This sensor has a max. measurement depth of 25 mm and operates at a Larmor frequency of 13.4 MHz. The general challenges of NMR in soils are the inherent fast transversal relaxation times of the soil matrix especially next to the residual moisture content. Therefore, as a first step of validation we applied and compared NMR-MOUSE measurements with magnetic resonance imaging (MRI) using an initially saturated sand column. The column was evaporated over 67 days and water content profiles were recorded by 1D-T2 relaxation measurements using the NMR-MOUSE as well as different 3D-MRI sequences during drying. Firstly, we report on the sensitivities and limits of the different devices and measurement sequences. Considering these data, we could monitor that over a period of 58 days the moisture decreased rather uniform until the onset of stage II. Thereafter, a dry surface layer developed and a retreating drying front was observed.

  10. Theoretical Determination of The Optimum Thickness of Perylene Layer in Bilayer Phthalocyanine/Perylene Photovoltaic Device

    NASA Astrophysics Data System (ADS)

    Pratiwi, Herlina; Siahaan, Timothy; Satriawan, Mirza; Nurwantoro, Pekik; Triyana, Kuwat

    2009-09-01

    We do theoretical study on thickness of the active layers in a heterojunction bilayer thin film photovoltaic device based on copper phthalocyanine (CuPc)/perylene that gives the highest Incident Photon to Current Efficiency (IPCE). The device we study consists Glass (1 mm)/ITO (Indium Tin Oxide, 120 nm)/CuPc (50 nm)/PTCDA (3, 4, 9, 10-perylenetetracarboxylic dianhydride, x nm)/Ag (40 nm), where x is the thickness of the PTCDA layer that we calculate here. The calculation is based on assumption that the photocurrent generation process is the result of the creation of photogenerated excitons, which difuse before dissociated at the CuPc/PTCDA interface following the diffusion equation, by internal optical electric field that comes from light exposure. We also assume that almost all photocurrent is created in the CuPc/PTCDA interface. Because the order of the thickness of the active layers is the same or smaller than of the wavelength of visible light, we take into account the effect of reflection and interference in the calculation of internal optical electric field distribution inside the device by making use complex indices of refraction of the active materials in our calculation. The modulus of it is proportional with the number generated excitons. The general solution of the exciton diffusion equation was used for calculating the photocurrent and the IPCE. Here, we find the optimum thickness of PTCDA layer that gives greatest IPCE at the wavelength of 344 nm and 467 nm, which are the wavelengths at which the absorption coefficients of CuPc and PTCDA, respectively, reach the maximum values.

  11. A bulk similarity approach in the atmospheric boundary layer using radiometric skin temperature to determine regional surface fluxes

    NASA Technical Reports Server (NTRS)

    Brutsaert, Wilfried; Sugita, Michiaki

    1991-01-01

    Profiles of wind velocity and temperature in the outer region of the atmospheric boundary layer (ABL) were used together with surface temperature measurements, to determine regional shear stress and sensible heat flux by means of transfer parameterizations on the basis of bulk similarity. The profiles were measured by means of radiosondes and the surface temperatures by infrared radiation thermometry over hilly prairie terrain in northeastern Kansas during the First ISLSCP Field Experiment (FIFE). In the analysis, the needed similarity functions were determined and tested.

  12. RF microalgal lipid content characterization.

    PubMed

    Al Ahmad, Mahmoud; Al-Zuhair, Sulaiman; Taher, Hanifa; Hilal-Alnaqbi, Ali

    2014-01-01

    Most conventional techniques for the determination of microalgae lipid content are time consuming and in most cases are indirect and require excessive sample preparations. This work presents a new technique that utilizes radio frequency (RF) for rapid lipid quantification, without the need for sample preparation. Tests showed that a shift in the resonance frequency of a RF open-ended coaxial resonator and a gradual increase in its resonance magnitude may occur as the lipids content of microalgae cells increases. These response parameters can be then calibrated against actual cellular lipid contents and used for rapid determination of the cellular lipids. The average duration of lipid quantification using the proposed technique was of about 1 minute, which is significantly less than all other conventional techniques, and was achieved without the need for any time consuming treatment steps. PMID:24870372

  13. On determining field water capacity and available water in uniform and layered soil profiles: Critical accounts and Proposals

    NASA Astrophysics Data System (ADS)

    Ceres, F.; Chirico, G. B.; Romano, N.

    2009-04-01

    Field water capacity and available water concepts are major agronomic parameters widely used for irrigation management, especially in Mediterranean zones facing with shortage of water. However, their definitions are still under discussion among scientists and practitioners. Field water capacity is often determined using empirical relationships (e.g. pedotransfer functions) or from water retention points obtained in the laboratory, thus underplaying or even ignoring the important role exerted by the actual evolution of water redistribution processes in a soil profile, especially if it is a layered one. An objective and replicable method for determining the field water capacity requires monitoring a water redistribution process evolving in a soil profile thoroughly wetted by a preliminary infiltration phase. Accordingly, in this study free drainage processes in soil profiles have been simulated by applying the numerical model developed by Romano et al. (1998) and verified by Brunone et al. (2003). This model solves Richards' equation by applying the Crank-Nicolson finite difference technique and uses a numerical algorithm specifically designed in case of layered soils for calculating the hydraulic conductivity between soil layers. In addition, to ensure a good correspondence between the analyses performed and actual situations, an extensive database of uniform and layered soil profiles have been employed. Outcome from the scenarios on uniform soils have shown that soil water content values under the condition of field capacity do not match water content values obtained from water retention point measured at preselected matric pressure head. Similar results have been obtained when using retention data points retrieved from the use of well-established pedotransfer functions (such as the HYPRES-PTF). In case of layered soil profiles, which actually represent the rule rather than an exception, the layer sequence and reciprocal differences in the soil hydraulic properties

  14. Determination of heteroepitaxial layer relaxation at growth temperature from room temperature X-ray reciprocal space maps

    NASA Astrophysics Data System (ADS)

    Roesener, Tobias; Klinger, Vera; Weuffen, Christoph; Lackner, David; Dimroth, Frank

    2013-04-01

    Lattice-mismatched heteroepitaxial growth in compound semiconductor layer structures, e.g. metamorphic buffers, is frequently used to combine materials with favorable properties. A detailed understanding of the strain relaxation during growth is important to optimize the buffer layers and to achieve high material quality. We present a method to determine the epilayer relaxation at growth temperature from room temperature X-ray diffraction measurements. For this the lattice parameters are measured with (004) and (224) reciprocal space maps along two orthogonal <110> directions to account for anisotropic misfit strain relaxation. Dissimilar thermal expansion coefficients of substrate and epilayer are taken into consideration when calculating the lattice parameters and epilayer relaxation parameters at growth temperature. The application of this method is discussed for GaAsxP1-x metamorphic buffer structure on Si with eight lattice-mismatched layers showing a relaxation parameter of over 130% at room temperature. All layers were found to be nearly 100% relaxed at growth temperature. The use of this method for other compound semiconductors is discussed.

  15. MO-G-18C-07: Improving T2 Determination and Quantification of Lipid Methylene Protons in Proton Magnetic Resonance Spectroscopy at 3 T

    SciTech Connect

    Breitkreutz, D.; Fallone, B. G.; Yahya, A.

    2014-06-15

    Purpose: To improve proton magnetic resonance spectroscopy (MRS) transverse relaxation (T{sub 2}) determination and quantification of lipid methylene chain (1.3 ppm) protons by rewinding their J-coupling evolution. Methods: MRS experiments were performed on four lipid phantoms, namely, almond, corn, sunflower and oleic acid, using a 3 T Philips MRI scanner with a transmit/receive birdcage head coil. Two PRESS (Point RESolved Spectroscopy) pulse sequences were used. The first PRESS sequence employed standard bandwidth (BW) (∼550 Hz) RF (radiofrequency) refocussing pulses, while the second used refocussing pulses of narrow BW (∼50 Hz) designed to rewind J-coupling evolution of the methylene protons in the voxel of interest. Signal was acquired with each sequence from a 5×5×5 mm{sup 3} voxel, with a repetition time (TR) of 3000 ms, and with echo times (TE) of 100 to 200 ms in steps of 20 ms. 2048 sample points were measured with a 2000 Hz sampling bandwidth. Additionally, 30 mm outer volume suppression slabs were used to suppress signal outside the voxel of interest. The frequency of the RF pulses was set to that of the methylene resonance. Methylene peak areas were calculated and fitted in MATLAB to a monexponentially decaying function of the form M{sub 0}exp(-TE/T{sub 2}), where M{sub 0} is the extrapolated area when TE = 0 ms and yields a measure of concentration. Results: The determined values of M{sub 0} and T{sub 2} increased for all fatty acids when using the PRESS sequence with narrow BW refocussing pulses. M{sub 0} and T{sub 2} values increased by an average amount (over all the phantoms) of 31% and 14%, respectively. Conclusion: This investigation has demonstrated that J-coupling interactions of lipid methylene protons causes non-negligible signal losses which, if not accounted for, Result in underestimations of their levels and T{sub 2} values when performing MRS measurements. Funded by the Natural Sciences and Engineering Research Council of Canada

  16. Adjusting membrane lipids under salt stress: the case of the moderate halophilic organism Halobacillus halophilus.

    PubMed

    Lopalco, Patrizia; Angelini, Roberto; Lobasso, Simona; Köcher, Saskia; Thompson, Melanie; Müller, Volker; Corcelli, Angela

    2013-04-01

    The lipid composition of Halobacillus halophilus was investigated by combined thin-layer chromatography and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analyses of the total lipid extract. Main polar lipids were found to be sulfoquinovosyldiacylglycerol and phosphatidylglycerol, while cardiolipin was a minor lipid together with phosphatidic acid, alanyl-phosphatidylglycerol and two not yet fully identified lipid components. In addition the analyses of residual lipids, associated with denatured proteins after the lipid extraction, revealed the presence of significant amounts of cardiolipin, indicating that it is a not readily extractable phospholipid. Post decay source mass spectrometry analyses allowed the determination of acyl chains of main lipid components. On increasing the culture medium salinity, an increase in the shorter chains and the presence of chain unsaturations were observed. These changes in the lipid core structures might compensate for the increase in packing and rigidity of phospholipid and sulfoglycolipid polar heads in high-salt medium, therefore contributing to the homeostasis of membrane fluidity and permeability in salt stress conditions. PMID:22970819

  17. Satb2 is a postmitotic determinant for upper-layer neuron specification in the neocortex.

    PubMed

    Britanova, Olga; de Juan Romero, Camino; Cheung, Amanda; Kwan, Kenneth Y; Schwark, Manuela; Gyorgy, Andrea; Vogel, Tanja; Akopov, Sergey; Mitkovski, Miso; Agoston, Denes; Sestan, Nenad; Molnár, Zoltán; Tarabykin, Victor

    2008-02-01

    Pyramidal neurons of the neocortex can be subdivided into two major groups: deep- (DL) and upper-layer (UL) neurons. Here we report that the expression of the AT-rich DNA-binding protein Satb2 defines two subclasses of UL neurons: UL1 (Satb2 positive) and UL2 (Satb2 negative). In the absence of Satb2, UL1 neurons lose their identity and activate DL- and UL2-specific genetic programs. UL1 neurons in Satb2 mutants fail to migrate to superficial layers and do not contribute to the corpus callosum but to the corticospinal tract, which is normally populated by DL axons. Ctip2, a gene required for the formation of the corticospinal tract, is ectopically expressed in all UL1 neurons in the absence of Satb2. Satb2 protein interacts with the Ctip2 genomic region and controls chromatin remodeling at this locus. Satb2 therefore is required for the initiation of the UL1-specific genetic program and for the inactivation of DL- and UL2-specific genes. PMID:18255031

  18. Conduction band offset determination between strained CdSe and ZnSe layers using DLTS

    SciTech Connect

    Rangel-Kuoppa, Victor-Tapio

    2013-12-04

    The conduction band offset between strained CdSe layers embedded in unintentionally n-type doped ZnSe is measured and reported. Two samples, consisting of thirty Ultra Thin Quantum Wells (UTQWs) of CdSe embedded in ZnSe, grown by Atomic Layer Epitaxy, are used for this study. The thicknesses of the UTQWs are one and three monolayers (MLs) in each sample, respectively. As expected, the sample with one ML UTQWs does not show any energy level in the UTQWs due to the small thickness of the UTQWs, while the thickness of the sample with 3 ML UTQWs is large enough to form an energy level inside the UTQWs. This energy level appears as a majority trap with an activation energy of 223.58 ± 9.54 meV. This corresponds to UTQWs with barrier heights (the conduction band offset) between 742 meV and 784 meV. These values suggest that the band gap misfit between strained CdSe and ZnSe is around 70.5 to 74 % in the conduction band.

  19. Determining the efficiency of subjecting finely dispersed emulsions to physical coagulation in a packed layer under turbulent conditions

    NASA Astrophysics Data System (ADS)

    Laptev, A. G.; Basharov, M. M.; Farakhova, A. I.

    2013-09-01

    The process through which small droplets contained in emulsions are physically coagulated on the surface of random packing elements is considered. The theory of turbulent migration of a finely dispersed phase is used for determining the coagulation efficiency. Expressions for calculating coagulation efficiency and turbulent transfer rate are obtained by applying models of a turbulent boundary layer. An example of calculating the enlargement of water droplets in hydrocarbon medium represented by a wide fraction of light hydrocarbons (also known as natural gas liquid) is given. The process flowchart of a system for removing petroleum products from effluent waters discharged from the Kazan TETs-1 cogeneration station is considered. Replacement of the mechanical filter by a thin-layer settler with a coagulator is proposed.

  20. An Introduction to Lipid Analysis in the Cell Biology Laboratory.

    ERIC Educational Resources Information Center

    Schuh, Timothy J.

    2002-01-01

    Explains a thin-layer chromatography (TLC) experiment that allows students to study complex mixtures of lipids using small volumes. Uses a water-soluble dye to stain lipids that is fast and safe. (YDS)

  1. Organic membranes determine the pattern of the columnar prismatic layer of mollusc shells.

    PubMed

    Checa, Antonio G; Macías-Sánchez, Elena; Harper, Elizabeth M; Cartwright, Julyan H E

    2016-05-11

    The degree to which biological control is exercised compared to physical control of the organization of biogenic materials is a central theme in biomineralization. We show that the outlines of biogenic calcite domains with organic membranes are always of simple geometries, while without they are much more complex. Moreover, the mineral prisms enclosed within the organic membranes are frequently polycrystalline. In the prismatic layer of the mollusc shell, organic membranes display a dynamics in accordance with the von Neumann-Mullins and Lewis Laws for two-dimensional foam, emulsion and grain growth. Taken together with the facts that we found instances in which the crystals do not obey such laws, and that the same organic membrane pattern can be found even without the mineral infilling, our work indicates that it is the membranes, not the mineral prisms, that control the pattern, and the mineral enclosed within the organic membranes passively adjusts to the dynamics dictated by the latter. PMID:27147096

  2. How oil properties and layer thickness determine the entrainment of spilled surface oil.

    PubMed

    Zeinstra-Helfrich, Marieke; Koops, Wierd; Murk, Albertinka J

    2016-09-15

    Viscosity plays an important role in dispersion of spilled surface oil, so does adding chemical dispersants. For seven different oil grades, entrainment rate and initial droplet size distribution were investigated using a plunging jet apparatus with coupled camera equipment and subsequent image analysis. We found that amount of oil entrained is proportional to layer thickness and largely independent of oil properties: A dispersant dose of 1:200 did not result in a significantly different entrainment rate compared to no dispersants. Oil viscosity had a minor to no influence on entrainment rate, until a certain threshold above which entrainment was impeded. The mean droplet size scales with the modified Weber number as described by Johansen. The obtained results can help improve dispersion algorithms in oil spill fate and transport models, to aid making an informed decision about application of dispersants. PMID:27345705

  3. On determination of formaldehyde content in atmospheric boundary layer for overcast using DOAS technique

    NASA Astrophysics Data System (ADS)

    Postylyakov, Oleg; Borovski, Alexander; Ivanov, Victor

    2015-11-01

    Formaldehyde (HCHO) is involved in a lot of chemical reactions in the atmosphere. Taking into account that HCHO basically undergo by photolysis and reaction with hydroxyl radical within a few hours, short-lived VOCs and direct HCHO emissions can cause local HCHO enhancement over certain areas, and, hence, exceeding background level of HCHO can be examined as a local pollution of the atmosphere by VOCs or existence of a local HCHO source. Several retrieval algorithms applicable for DOAS measurements in cloudless were previously developed. A new algorithm applicable for overcast and cloudless sky and its error analysis is briefly introduced by this paper. Analysis of our HCHO VCD retrieval for overcast shows that when one know the cloud base height, but doesn't know cloud optical depth, the typical errors of HCHO total content retrieval are less than 10% for snow season, less than 5% for snow-free seasons, and reaches 40-45% for season with non-stable snow cover. In case one knows both the cloud base height and the cloud optical depth, the typical errors are about 5% for snow season, less than 2.5% for snow-free seasons, and are within about 10-30% for season with non-stable snow cover. Given above error estimations are valid if the HCHO layer is below the cloud base. The errors dramatically increase when HCHO layer penetrates into clouds in both cases. The first preliminary results of HCHO VCD retrieval for overcast are shown. The average difference of the HCHO VCDs for wind from Moscow megapolis and wind from few urbanized areas is about 0.8×1016 mol×cm-2 and approximately corresponds to estimates of influence of Moscow megapolis observed in clear-sky conditions.

  4. Determination of pigments in colour layers on walls of some selected historical buildings using optical and scanning electron microscopy

    SciTech Connect

    Skapin, A. Sever Ropret, P. Bukovec, P.

    2007-11-15

    For successful restoration of painted walls and painted coloured finishing coats it is necessary to determine the composition of the original colour layers. Identification of the pigments used in The Cistercian Abbey of Sticna and The Manor of Novo Celje was carried out using optical and scanning electron microscopy. Selected samples of wall paintings were inspected by the combined application of an optical microscope and a low-vacuum Scanning Electron Microscope to determine their colour and structural features and to identify the position of individual pigment grains. Energy dispersive spectroscopy was used to determine the elemental distribution on selected surfaces and elemental composition of individual pigments. It was found that the most abundantly used pigments were iron oxide red, cinnabar, green earth, umber, calcium carbonate white, ultramarine, yellow ochre and carbon black. These identifications have allowed us to compare the use of various pigments in buildings from different historical periods.

  5. Lipid peroxidation and tissue damage.

    PubMed

    Mylonas, C; Kouretas, D

    1999-01-01

    In recent years it has become apparent that the oxidation of lipids, or lipid peroxidation, is a crucial step in the pathogenesis of several disease states in adult and infant patients. Lipid peroxidation is a process generated naturally in small amounts in the body, mainly by the effect of several reactive oxygen species (hydroxyl radical, hydrogen peroxide etc.). It can also be generated by the action of several phagocytes. These reactive oxygen species readily attack the polyunsaturated fatty acids of the fatty acid membrane, initiating a self-propagating chain reaction. The destruction of membrane lipids and the end-products of such lipid peroxidation reactions are especially dangerous for the viability of cells, even tissues. Enzymatic (catalase, superoxide dismutasse) and nonenzymatic (vitamins A and E) natural antioxidant defence mechanisms exist; however, these mechanisms may be overcome, causing lipid peroxidation to take place. Since lipid peroxidation is a self-propagating chain-reaction, the initial oxidation of only a few lipid molecules can result in significant tissue damage. Despite extensive research in the field of lipid peroxidation it has not yet been precisely determined if it is the cause or an effect of several pathological conditions. Lipid peroxidation has been implicated in disease states such as atherosclerosis, IBD, ROP, BPD, asthma, Parkinson's disease, kidney damage, preeclampsia and others. PMID:10459507

  6. Paternal B Vitamin Intake Is a Determinant of Growth, Hepatic Lipid Metabolism and Intestinal Tumor Volume in Female Apc1638N Mouse Offspring

    PubMed Central

    Sabet, Julia A.; Park, Lara K.; Iyer, Lakshmanan K.; Tai, Albert K.; Koh, Gar Yee; Pfalzer, Anna C.; Parnell, Laurence D.; Mason, Joel B.; Liu, Zhenhua; Byun, Alexander J.; Crott, Jimmy W.

    2016-01-01

    Background The importance of maternal nutrition to offspring health and risk of disease is well established. Emerging evidence suggests paternal diet may affect offspring health as well. Objective In the current study we sought to determine whether modulating pre-conception paternal B vitamin intake alters intestinal tumor formation in offspring. Additionally, we sought to identify potential mechanisms for the observed weight differential among offspring by profiling hepatic gene expression and lipid content. Methods Male Apc1638N mice (prone to intestinal tumor formation) were fed diets containing replete (control, CTRL), mildly deficient (DEF), or supplemental (SUPP) quantities of vitamins B2, B6, B12, and folate for 8 weeks before mating with control-fed wild type females. Wild type offspring were euthanized at weaning and hepatic gene expression profiled. Apc1638N offspring were fed a replete diet and euthanized at 28 weeks of age to assess tumor burden. Results No differences in intestinal tumor incidence or burden were found between male Apc1638N offspring of different paternal diet groups. Although in female Apc1638N offspring there were no differences in tumor incidence or multiplicity, a stepwise increase in tumor volume with increasing paternal B vitamin intake was observed. Interestingly, female offspring of SUPP and DEF fathers had a significantly lower body weight than those of CTRL fed fathers. Moreover, hepatic trigylcerides and cholesterol were elevated 3-fold in adult female offspring of SUPP fathers. Weanling offspring of the same fathers displayed altered expression of several key lipid-metabolism genes. Hundreds of differentially methylated regions were identified in the paternal sperm in response to DEF and SUPP diets. Aside from a few genes including Igf2, there was a striking lack of overlap between these genes differentially methylated in sperm and differentially expressed in offspring. Conclusions In this animal model, modulation of

  7. Polar lipids from oat kernels

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Oat (Avena sativa L.) kernels appear to contain much higher polar lipid concentrations than other plant tissues. We have extracted, identified, and quantified polar lipids from 18 oat genotypes grown in replicated plots in three environments in order to determine genotypic or environmental variation...

  8. Fatty-acid profile of total and polar lipids in cultured rainbow trout (Oncorhynchus mykiss) raised in freshwater and seawater (Croatia) determined by transmethylation method.

    PubMed

    Staver, Mladenka Malenica; Jerković, Igor; Giacometti, Jasminka; Malenica, Ante; Marijanović, Zvonimir

    2012-08-01

    Fatty acids from total lipids and polar lipids in cultured rainbow trout (Oncorhynchus mykiss) raised in seawater (SW) and freshwater (FW) were identified and quantified from the muscle samples in January, April, and July. The highest total lipid and polar lipid amounts were found in April. July contents of total lipids were low, but percent of the polyunsaturated fatty acids (PUFAs) was high in SW and FW environment (particularly n-3 PUFAs). Variety of 17 fatty acids was identified by GC-FID after transmethylation. The predominant fatty acids in rainbow trout from SW and FW were: docosahexaenoic acid among n-3 PUFAs, palmitic acid among saturated fatty acids (SFAs), and oleic acid among monounsaturated fatty acids (MUFAs). Appreciably higher n-3/n-6 ratio was found in total lipids in April (6.40, FW fish) and in polar lipids in July (18.76; SW fish). High n-3/n-6 ratio in total lipids and polar lipids of rainbow trout from SW and FW, besides beneficial n-3/n-6 ratio in the commercial fish food, could be characteristic for the local environmental conditions (Croatia). PMID:22899619

  9. On the determination of the position of laminar-turbulent transition in boundary layer by optical methods

    NASA Astrophysics Data System (ADS)

    Bountin, D. A.; Gromyko, Yu. V.; Maslov, A. A.; Polivanov, P. A.; Sidorenko, A. A.

    2015-11-01

    As a rule, aerodynamic studies at hypersonic flow velocities are carried out in short-duration wind-tunnel facilities. For such facilities, optical diagnostic methods are most preferable. In the present study, we give for the first time a comparison of two methods for determining the end of laminar-turbulent transition: from the distribution of heat fluxes and from schlieren visualization data for the boundary-layer flow. Parametric data on the position of the transition are obtained. These data can be used in the future as reference ones while calibrating semi-empirical calculation models for the transition.

  10. Determination of Optimal Parameters for Dual-Layer Cathode of Polymer Electrolyte Fuel Cell Using Computational Intelligence-Aided Design

    PubMed Central

    Chen, Yi; Huang, Weina; Peng, Bei

    2014-01-01

    Because of the demands for sustainable and renewable energy, fuel cells have become increasingly popular, particularly the polymer electrolyte fuel cell (PEFC). Among the various components, the cathode plays a key role in the operation of a PEFC. In this study, a quantitative dual-layer cathode model was proposed for determining the optimal parameters that minimize the over-potential difference and improve the efficiency using a newly developed bat swarm algorithm with a variable population embedded in the computational intelligence-aided design. The simulation results were in agreement with previously reported results, suggesting that the proposed technique has potential applications for automating and optimizing the design of PEFCs. PMID:25490761

  11. Determination of composition of non-homogeneous GaInNAs layers

    NASA Astrophysics Data System (ADS)

    Pucicki, D.; Bielak, K.; Ściana, B.; Radziewicz, D.; Latkowska-Baranowska, M.; Kováč, J.; Vincze, A.; Tłaczała, M.

    2016-01-01

    Dilute nitride GaInNAs alloys grown on GaAs have become perspective materials for so called low-cost GaAs-based devices working within the optical wavelength range up to 1.6 μm. The multilayer structures of GaInNAs/GaAs multi-quantum well (MQW) samples usually are analyzed by using high resolution X-ray diffraction (HRXRD) measurements. However, demands for precise structural characterization of the GaInNAs containing heterostructures requires taking into consideration all inhomogeneities of such structures. This paper describes some of the material challenges and progress in structural characterization of GaInNAs layers. A new algorithm for structural characterization of dilute nitrides which bounds contactless electro-reflectance (CER) or photo-reflectance (PR) measurements and HRXRD analysis results together with GaInNAs quantum well band diagram calculation is presented. The triple quantum well (3QW) GaInNAs/GaAs structures grown by atmospheric-pressure metalorganic vapor-phase epitaxy (AP-MOVPE) were investigated according to the proposed algorithm. Thanks to presented algorithm, more precise structural data including the nonuniformity in the growth direction of GaInNAs/GaAs QWs were achieved. Therefore, the proposed algorithm is mentioned as a nondestructive method for characterization of multicomponent inhomogeneous semiconductor structures with quantum wells.

  12. Lipid Nanotechnology

    PubMed Central

    Mashaghi, Samaneh; Jadidi, Tayebeh; Koenderink, Gijsje; Mashaghi, Alireza

    2013-01-01

    Nanotechnology is a multidisciplinary field that covers a vast and diverse array of devices and machines derived from engineering, physics, materials science, chemistry and biology. These devices have found applications in biomedical sciences, such as targeted drug delivery, bio-imaging, sensing and diagnosis of pathologies at early stages. In these applications, nano-devices typically interface with the plasma membrane of cells. On the other hand, naturally occurring nanostructures in biology have been a source of inspiration for new nanotechnological designs and hybrid nanostructures made of biological and non-biological, organic and inorganic building blocks. Lipids, with their amphiphilicity, diversity of head and tail chemistry, and antifouling properties that block nonspecific binding to lipid-coated surfaces, provide a powerful toolbox for nanotechnology. This review discusses the progress in the emerging field of lipid nanotechnology. PMID:23429269

  13. Ab Initio determination of Cu 3d orbital energies in layered copper oxides

    PubMed Central

    Hozoi, Liviu; Siurakshina, Liudmila; Fulde, Peter; van den Brink, Jeroen

    2011-01-01

    It has long been argued that the minimal model to describe the low-energy physics of the high Tc superconducting cuprates must include copper states of other symmetries besides the canonical one, in particular the orbital. Experimental and theoretical estimates of the energy splitting of these states vary widely. With a novel ab initio quantum chemical computational scheme we determine these energies for a range of copper-oxides and -oxychlorides, determine trends with the apical Cu–ligand distances and find excellent agreement with recent Resonant Inelastic X-ray Scattering measurements, available for La2CuO4, Sr2CuO2Cl2, and CaCuO2. PMID:22355584

  14. Semiquantitative determination of polychlorinated biphenyls in tissue samples by thin layer chromatography

    USGS Publications Warehouse

    Mulhern, B.M.; Cromartie, E.; Reichel, W.L.; Belisle, A.A.

    1971-01-01

    A method is described for the analysis of polychlorinated biphenyl (PCB) compounds in tissue samples. Cleanup by hexane-aceto-nitrile partitioning and Florisil column chromatography are performed on samples before oxidative treatment to convert DDE to DCBP. PCB components are then determined semi-quantitatively by TLC. No prior separation of PCB from chlorinated pesticides is required. The lower limit of sensitivity is 0.2 ?g.

  15. Effects of lipid composition on the membrane activity and lipid phase behaviour of Vibrio sp. DSM14379 cells grown at various NaCl concentrations.

    PubMed

    Danevcic, Tjasa; Rilfors, Leif; Strancar, Janez; Lindblom, Göran; Stopar, David

    2005-06-15

    The membrane lipid composition of living cells generally adjusts to the prevailing environmental and physiological conditions. In this study, membrane activity and lipid composition of the Gram-negative bacterium Vibrio sp. DSM14379, grown aerobically in a peptone-yeast extract medium supplemented with 0.5, 1.76, 3, 5 or 10% (w/v) NaCl, was determined. The ability of the membrane to reduce a spin label was studied by EPR spectroscopy under different salt concentrations in cell suspensions labeled with TEMPON. For lipid composition studies, cells were harvested in a late exponential phase and lipids were extracted with chloroform-methanol-water, 1:2:0.8 (v/v). The lipid polar head group and acyl chain compositions were determined by thin-layer and gas-liquid chromatographies. (31)P-NMR spectroscopy was used to study the phase behaviour of the cell lipid extracts with 20 wt.% water contents in a temperature range from -10 to 50 degrees C. The results indicate that the ability of the membrane to reduce the spin label was highest at optimal salt concentrations. The composition of both polar head groups and acyl chains changed markedly with increasing salinity. The fractions of 16:0, 16:1 and 18:0 acyl chains increased while the fraction of 18:1 acyl chains decreased with increasing salinity. The phosphatidylethanolamine fraction correlated inversely with the lysophosphatidylethanolamine fraction, with phosphatidylethanolamine exhibiting a minimum, and lysophosphatidylethanolamine a maximum, at the optimum growth rate. The fraction of lysophosphatidylethanolamine was surprisingly high in the lipid extracts. This lipid can form normal micellar and hexagonal phases and it was found that all lipid extracts form a mixture of lamellar and normal isotropic liquid crystalline phases. This is an anomalous behaviour since the nonlamellar phases formed by total lipid extracts are generally of the reversed type. PMID:15878424

  16. Determination of the layer-specific distributed collagen fibre orientations in human thoracic and abdominal aortas and common iliac arteries

    PubMed Central

    Schriefl, Andreas J.; Zeindlinger, Georg; Pierce, David M.; Regitnig, Peter; Holzapfel, Gerhard A.

    2012-01-01

    The established method of polarized microscopy in combination with a universal stage is used to determine the layer-specific distributed collagen fibre orientations in 11 human non-atherosclerotic thoracic and abdominal aortas and common iliac arteries (63 ± 15.3 years, mean ± s.d.). A dispersion model is used to quantify over 37 000 recorded fibre angles from tissue samples. The study resulted in distinct fibre families, fibre directions, dispersion and thickness data for each layer and all vessels investigated. Two fibre families were present for the intima, media and adventitia in the aortas, with often a third and sometimes a fourth family in the intima in the respective axial and circumferential directions. In all aortas, the two families were almost symmetrically arranged with respect to the cylinder axis, closer to the axial direction in the adventitia, closer to the circumferential direction in the media and in between in the intima. The same trend was found for the intima and adventitia of the common iliac arteries; however, there was only one preferred fibre alignment present in the media. In all locations and layers, the observed fibre orientations were always in the tangential plane of the walls, with no radial components and very small dispersion through the wall thickness. A wider range of in-plane fibre orientations was present in the intima than in the media and adventitia. The mean total wall thickness for the aortas and the common iliac artery was 1.39 and 1.05 mm, respectively. For the aortas, a slight thickening of the intima and a thinning of the media in increasingly distal regions were observed. A clear intimal thickening was present distal to the branching of the celiac arteries. All data, except for the media of the common iliac arteries, showed two prominent collagen fibre families for all layers so that two-fibre family models seem most appropriate. PMID:22171063

  17. Comparison of Methods to Determine Tropical Tropopause Layer Cirrus Formation Mechanisms

    SciTech Connect

    Riihimaki, Laura D.; McFarlane, Sally A.; Liang, Calvin; Massie, Steven T.; Beagley, Nathaniel; Toth, Travis D.

    2012-03-30

    A new method of estimating Tropical Tropopause Layer Cirrus (TTLC) formation mechanism (object method) is compared to interpretations of formation from previous studies using back trajectory calculations matched to convection identified from satellites and statistical relationships of TTLC with temperature and water vapor. The object method groups neighboring Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) TTLC cloud profiles into cloud objects and classifies them as convective (35% of TTLC) if they are directly attached to a convective cloud along the CALIPSO track. The percentage of back trajectory calculations that intersect convection (39-95% of TTLC within 5 days) depends strongly on the spatial and temporal resolution of the convection data set, and the manner in which deep convection is identified. Using minimum brightness temperature in 3 hourly, 1{sup o} resolution grid boxes to define convection, 46% of non-convective TTLC (37% of all TTLC) did not trace back to convection within 24 h. Back trajectory calculations of thin cirrus identified by the High Resolution Dynamics Limb Sounder (HIRDLS) gave similar results. Temperature is not a good proxy for formation mechanism as convective and non-convective TTLC frequencies both increase monotonically with decreasing temperature at approximately the same rate. Non-convective TTLC frequencies have a stronger relationship with relative humidity than convective TTLC frequencies, though are not sufficiently different to distinguish object method categories. A decrease in TTL cirrus frequency found at low temperatures in previous studies is caused by insufficient variability in reanalysis temperature data and is not indicative of TTLC formation mechanism.

  18. Bergenin determination in different extracts by high-performance thin-layer chromatographic densitometry

    PubMed Central

    Khan, Masood Shah; Khan, Washim; Ahmad, Wasim; Singh, Mhaveer; Ahmad, Sayeed

    2015-01-01

    Aim: Bergenin is an active secondary metabolite, found in Bergenia ligulata, family Saxifragaceae, which is an important medicinal plant used in the traditional system of medicine. It is distributed throughout the South and East Asia and some European countries, usually growing on high altitude in the Himalayan region and known as Pashanbhed (meaning “to break the stone”). The rhizome of B. ligulata has been used since long time in different traditional formulations of kidney and liver disorders. Due to its exhaustive use in the traditional system, it is commonly adulterated with the rhizome of other plants which do not contain its chemical marker bergenin. Hence, we developed high-performance thin-layer chromatographic (HPTLC) method for quantification of bergenin in B. ligulata which can be used for its quality control. Materials and Methods: A sensitive HPTLC method has been developed for the estimation of bergenin in different extracts of B. ligulata and its traditional formulations. Precoated HPTLC silica gel plates were used as stationary phase, and chloroform: methanol: acetic acid (8:1:1, v/v/v) was used as mobile phase. Results: The Rf value of bergenin was found to be 0.28 ± 0.03. Detection and quantification were performed by densitometry at 276 nm. The calibration plot was linear in the range of 200–5000 ng of bergenin with the correlation coefficient of (r2) 0.999, which confirms good linearity. The content of bergenin in methanolic and acetone extracts was found to be 5.51 ± 0.14 and 5.76 ± 0.16, respectively. Conclusion: The method can be applied for quality control and standardization of B. ligulata and its traditional formulations as well as for checking the presence of adulterants. PMID:26681881

  19. Contact-free sheet resistance determination of large area graphene layers by an open dielectric loaded microwave cavity

    SciTech Connect

    Shaforost, O.; Wang, K.; Adabi, M.; Guo, Z.; Hanham, S.; Klein, N.; Goniszewski, S.; Gallop, J.; Hao, L.

    2015-01-14

    A method for contact-free determination of the sheet resistance of large-area and arbitrary shaped wafers or sheets coated with graphene and other (semi) conducting ultrathin layers is described, which is based on an open dielectric loaded microwave cavity. The sample under test is exposed to the evanescent resonant field outside the cavity. A comparison with a closed cavity configuration revealed that radiation losses have no significant influence of the experimental results. Moreover, the microwave sheet resistance results show good agreement with the dc conductivity determined by four-probe van der Pauw measurements on a set of CVD samples transferred on quartz. As an example of a practical application, correlations between the sheet resistance and deposition conditions for CVD graphene transferred on quartz wafers are described. Our method has a high potential as measurement standard for contact-free sheet resistance measurement and mapping of large area graphene samples.

  20. Contact-free sheet resistance determination of large area graphene layers by an open dielectric loaded microwave cavity

    NASA Astrophysics Data System (ADS)

    Shaforost, O.; Wang, K.; Goniszewski, S.; Adabi, M.; Guo, Z.; Hanham, S.; Gallop, J.; Hao, L.; Klein, N.

    2015-01-01

    A method for contact-free determination of the sheet resistance of large-area and arbitrary shaped wafers or sheets coated with graphene and other (semi) conducting ultrathin layers is described, which is based on an open dielectric loaded microwave cavity. The sample under test is exposed to the evanescent resonant field outside the cavity. A comparison with a closed cavity configuration revealed that radiation losses have no significant influence of the experimental results. Moreover, the microwave sheet resistance results show good agreement with the dc conductivity determined by four-probe van der Pauw measurements on a set of CVD samples transferred on quartz. As an example of a practical application, correlations between the sheet resistance and deposition conditions for CVD graphene transferred on quartz wafers are described. Our method has a high potential as measurement standard for contact-free sheet resistance measurement and mapping of large area graphene samples.

  1. Determination of composition and energy gaps of GaInNAsSb layers grown by MBE

    NASA Astrophysics Data System (ADS)

    Aho, A.; Korpijärvi, V.-M.; Isoaho, R.; Malinen, P.; Tukiainen, A.; Honkanen, M.; Guina, M.

    2016-03-01

    We present a method to accurately determine the composition of GaInNAsSb heterostructures and a modified band anti-crossing model to calculate the corresponding bandgaps. The composition determination method is based on combining x-ray diffractometry and energy dispersive x-ray spectroscopy measurements. The modified band anti-crossing model was derived from the model known for GaInNAs and using band-gap composition relations for GaInAs, GaInSb, InAsSb and GaAsSb. The model parameters were defined by fitting with experimental bandgap data retrieved from photoluminescence. For validation and data fitting we used experimental samples with N composition in the range of 0-0.06, In composition from 0 to 0.17, and Sb composition in the range of 0-0.08. All samples were thermally annealed to minimize the band gap shift caused by the short range ordering effects in GaInNAsSb crystal. The modified model yields an excellent fit to the experimental band gap data with an accuracy of ~20 meV, and is a practical tool for designing, fabricating and analyzing optoelectronics devices.

  2. Determination of uptake kinetics (sampling rates) by lipid-containing semipermeable membrane devices (SPMDs) for polycyclic aromatic hydrocarbons (PAHs) in water

    USGS Publications Warehouse

    Huckins, J.N.; Petty, J.D.; Orazio, C.E.; Lebo, J.A.; Clark, R.C.; Gibson, V.L.; Gala, W.R.; Echols, K.R.

    1999-01-01

    The use of lipid-containing semipermeable membrane devices (SPMDs) is becoming commonplace, but very little sampling rate data are available for the estimation of ambient contaminant concentrations from analyte levels in exposed SPMDs. We determined the aqueous sampling rates (R(s)s; expressed as effective volumes of water extracted daily) of the standard (commercially available design) 1-g triolein SPMD for 15 of the priority pollutant (PP) polycyclic aromatic hydrocarbons (PAHs) at multiple temperatures and concentrations. Under the experimental conditions of this study, recovery- corrected R(s) values for PP PAHs ranged from ???1.0 to 8.0 L/d. These values would be expected to be influenced by significant changes (relative to this study) in water temperature, degree of biofouling, and current velocity- turbulence. Included in this paper is a discussion of the effects of temperature and octanol-water partition coefficient (K(ow)); the impacts of biofouling and hydrodynamics are reported separately. Overall, SPMDs responded proportionally to aqueous PAH concentrations; i.e., SPMD R(s) values and SPMD-water concentration factors were independent of aqueous concentrations. Temperature effects (10, 18, and 26 ??C) on Rs values appeared to be complex but were relatively small.The use of lipid-containing semipermeable membrane devices (SPMDs) is becoming commonplace, but very little sampling rate data are available for the estimation of ambient contaminant concentrations from analyte levels in exposed SPMDs. We determined the aqueous sampling rates (Rss; expressed as effective volumes of water extracted daily) of the standard (commercially available design) 1-g triolein SPMD for 15 of the priority pollutant (PP) polycyclic aromatic hydrocarbons (PAHs) at multiple temperatures and concentrations. Under the experimental conditions of this study, recovery-corrected Rs values for PP PAHs ranged from ???1.0 to 8.0 L/d. These values would be expected to be influenced by

  3. Lipid Storage Diseases

    MedlinePlus

    ... Awards Enhancing Diversity Find People About NINDS NINDS Lipid Storage Diseases Information Page Condensed from Lipid Storage ... en Español Additional resources from MedlinePlus What are Lipid Storage Diseases? Lipid storage diseases are a group ...

  4. Determining concentration fields of tracer plumes for layered porous media in flow-tank experiments

    NASA Astrophysics Data System (ADS)

    Yu, Zhongbo; Schwartz, Franklin W.

    In the laboratory, computer-assisted image analysis provides an accurate and efficient way to monitor tracer experiments. This paper describes the determination of detailed temporal concentration distributions of tracers in a flow-tank experiment by analyzing photographs of plumes of Rhodamine dye through the glass wall of the tank. The methodology developed for this purpose consists of four steps: (1) digitally scanning black and white negatives obtained from photographs of the flow-tank experiment; (2) calibrating and normalizing each digitized image to a standard optical-density scale by determining the relation between the optical density and pixel value for each image; (3) constructing standard curves relating the concentration in an optical density from five experimental runs with predetermined concentrations (2-97mg/L) and (4) converting the optical density to concentration. The spatial distribution of concentration for two photographs was determined by applying these calibration and conversion procedures to all pixels of the digitized images. This approach provides an efficient way to study patterns of plume evolution and transport mechanisms. Résumé Au laboratoire, l'analyse d'images assistée par ordinateur est un moyen précis et efficace pour suivre certaines expériences de traçage. Ce papier présente comment sont déterminées dans le détail les distributions temporelles de la concentration en traceur au cours d'une expérience d'écoulement en réservoir au moyen de l'analyse de photographies de panaches de rhodamine à travers la paroi de verre du réservoir. La méthodologie développée dans cette expérience suit quatre étapes: (1) digitalisation par balayage des négatifs noir et blanc des prises de vue de l'expérience d'écoulement en réservoir (2) calibration et normalisation de chaque image digitalisée par rapport à une échelle étalon de densité optique en déterminant la relation entre la densité optique et la valeur des pixels

  5. Mechanical properties of the superficial biofilm layer determine the architecture of biofilms.

    PubMed

    Kundukad, Binu; Seviour, Thomas; Liang, Yang; Rice, Scott A; Kjelleberg, Staffan; Doyle, Patrick S

    2016-06-29

    Cells in biofilms sense and interact with their environment through the extracellular matrix. The physicochemical properties of the matrix, particularly at the biofilm-environment interface, determine how cells respond to changing conditions. In this study we describe the application of atomic force microscopy and confocal imaging to probe in situ the mechanical properties of these interfacial regions and to elucidate how key matrix components can contribute to the physical sensing by the cells. We describe how the Young's modulus of microcolonies differs according to the size and morphology of microcolonies, as well as the flow rate. The Young's modulus increased as a function of microcolony diameter, which was correlated with the production of the polysaccharide Psl at later stages of maturation for hemispherical or mushroom shaped microcolonies. The Young's modulus of the periphery of the biofilm colony was however independent of the hydrodynamic shear. The morphology of the microcolonies also influenced interfacial or peripheral stiffness. Microcolonies with a diffuse morphology had a lower Young's modulus than isolated, circular ones and this phenomenon was due to a deficiency of Psl. In this way, changes in the specific polysaccharide components imbue the biofilm with distinct physical properties that may modulate the way in which bacteria perceive or respond to their environment. Further, the physical properties of the polysaccharides are closely linked to the specific architectures formed by the developing biofilm. PMID:27273453

  6. Lipid synthesis in chick epidermis.

    PubMed

    Lavker, R M

    1975-07-01

    Lipid synthesis in newborn chick epidermis was studied by electron microscopic autoradiography after injection of tritiated palmitate. The labeled lipid product in the tissue was identified as mostly triglyceride. At the earliest time after injection (6 hr), the radioactive precursor was taken up by all viable cells of the epidermis. Grain density was heaviest over basal cells, moderate over spinous cells, and slight over granular cells; thus lipid incorporation is highest in the basal and spinous regions of the chick epidermis. As time after injection progressed, the increasing amounts of grains over the granular and horny cells and decreasing amounts over the basal and spinous cells reflected the continuous upward displacement of cells from one layer into the next. From the distribution of silver grains within the epidermal cells, it has been concluded that, with the passage of time, triglycerides synthesized by the epidermal cells were mainly located in lipid droplets. The numerous grains associated with the elements of the endoplasmic reticulum indicated that this organelle is involved in aggregating triglyceride molecules into lipid droplets. The fact that grains were seen within the horny cells indicated that part of the horny cell consists of lipid probably derived from the lipid droplets retained by the cells during keratinization. PMID:1151110

  7. Effect of Different Broad Waveband Lights on Membrane Lipids of a Cyanobacterium, Synechococcus sp., as Determined by UPLC-QToF-MS and Vibrational Spectroscopy

    PubMed Central

    Montero, Olimpio; Velasco, Marta; Sanz-Arranz, Aurelio; Rull, Fernando

    2016-01-01

    Differential profile of membrane lipids and pigments of a Synechococcus sp. cyanobacterial strain cells exposed to blue, green, red and white light are determined by means of liquid chromatography and mass spectrometry or diode array detection. Raman and ATR-IR spectra of intact cells under the diverse light wavebands are also reported. Blue light cells exhibited an increased content of photosynthetic pigments as well as specific species of membrane glycerolipids as compared to cells exposed to other wavebands. The A630/A680 ratio indicated an increased content of phycobilisomes (PBS) in the blue light-exposed cells. Some differences in the protein conformation between the four light waveband-exposed cells were deduced from the variable absorbance at specific wavenumbers in the FT-Raman and ATR-FTIR spectra, in particular bands assigned to amide I and amide II. Bands from 1180 to 950 cm−1 in the ATR-FTIR spectrum suggest degraded outer membrane polysaccharide in the blue light-exposed cells. PMID:27223306

  8. A collision gradient method to determine the immersion depth of nitroxides in lipid bilayers: application to spin-labeled mutants of bacteriorhodopsin.

    PubMed Central

    Altenbach, C; Greenhalgh, D A; Khorana, H G; Hubbell, W L

    1994-01-01

    Ten mutants of bacteriorhodopsin, each containing a single cysteine residue regularly spaced along helix D and facing the lipid bilayer, were derivatized with a nitroxide spin label. Collision rates of the nitroxide with apolar oxygen increased with distance from the membrane/solution interface. Collision rates with polar metal ion complexes decreased over the same distance. Although the collision rates depend on steric constraints imposed by the local protein structure and on the depth in the membrane, the ratio of the collision rate of oxygen to those of a polar metal ion complex is independent of structural features of the protein. The logarithm of the ratio is a linear function of depth within the membrane. Calibration of this ratio parameter with spin-labeled phospholipids allows localization of the individual nitroxides, and hence the bacteriorhodopsin molecule, relative to the plane of the phosphate groups of the bilayer. The spacing between residues is consistent with the pitch of an alpha-helix. These results provide a general strategy for determining the immersion depth of nitroxides in bilayers. Images PMID:8127863

  9. Effect of Different Broad Waveband Lights on Membrane Lipids of a Cyanobacterium, Synechococcus sp., as Determined by UPLC-QToF-MS and Vibrational Spectroscopy.

    PubMed

    Montero, Olimpio; Velasco, Marta; Sanz-Arranz, Aurelio; Rull, Fernando

    2016-01-01

    Differential profile of membrane lipids and pigments of a Synechococcus sp. cyanobacterial strain cells exposed to blue, green, red and white light are determined by means of liquid chromatography and mass spectrometry or diode array detection. Raman and ATR-IR spectra of intact cells under the diverse light wavebands are also reported. Blue light cells exhibited an increased content of photosynthetic pigments as well as specific species of membrane glycerolipids as compared to cells exposed to other wavebands. The A630/A680 ratio indicated an increased content of phycobilisomes (PBS) in the blue light-exposed cells. Some differences in the protein conformation between the four light waveband-exposed cells were deduced from the variable absorbance at specific wavenumbers in the FT-Raman and ATR-FTIR spectra, in particular bands assigned to amide I and amide II. Bands from 1180 to 950 cm(-1) in the ATR-FTIR spectrum suggest degraded outer membrane polysaccharide in the blue light-exposed cells. PMID:27223306

  10. Lipid mobility in supported lipid bilayers by single molecule tracking

    NASA Astrophysics Data System (ADS)

    Kohram, Maryam; Shi, Xiaojun; Smith, Adam

    2015-03-01

    Phospholipid bilayers are the main component of cell membranes and their interaction with biomolecules in their immediate environment is critical for cellular functions. These interactions include the binding of polycationic polymers to lipid bilayers which affects many cell membrane events. As an alternative method of studying live cell membranes, we assemble a supported lipid bilayer and investigate its binding with polycationic polymers in vitro by fluorescently labeling the molecules of the supported lipid bilayer and tracking their mobility. In this work, we use single molecule tracking total internal reflection fluorescence microscopy (TIRF) to study phosphatidylinositol phosphate (PIP) lipids with and without an adsorbed polycationic polymer, quaternized polyvinylpyridine (QPVP). Individual molecular trajectories are obtained from the experiment, and a Brownian diffusion model is used to determine diffusion coefficients through mean square displacements. Our results indicate a smaller diffusion coefficient for the supported lipid bilayers in the presence of QPVP in comparison to its absence, revealing that their binding causes a decrease in lateral mobility.

  11. Piezoelectric layer embedded-microdiaphragm sensors for the determination of blood viscosity and density

    NASA Astrophysics Data System (ADS)

    Kim, Hye Jin; Kim, Jinsik; Zandieh, Omid; Chae, Myung-Sic; Kim, Tae Song; Lee, Jeong Hoon; Park, Jung Ho; Kim, Seonghwan; Hwang, Kyo Seon

    2014-10-01

    We introduce a lead zirconate titanate [PZT; Pb(Zr0.52Ti0.48)O3] microdiaphragm resonating sensor packaged in a polydimethylsiloxane chip. The proposed sensor can measure the density and viscosity of a liquid that is within the density and viscosity regime of blood (1.060 × 103 kg/m3, 3-4 cP). To verify the basic characteristics of the sensor, viscous solutions were prepared from glycerol and deionized water with a density in the range from 0.998 to 1.263 × 103 kg/m3 and a viscosity in the range from 1 to 1414 cP. We measured the frequency responses of the sensor before and after injecting the viscosity- and density-controlled liquid under the bottom of the microdiaphragm. The resonant frequencies in the (1,1) and (2,2) modes decreased linearly as a function of the liquid density in the range from 0.998 to 1.146 × 103 kg/m3 with a sensitivity of 28.03 Hz/kg.m-3 and 81.85 Hz/kg.m-3, respectively. The full width at half maximum had a logarithmic relationship with the liquid viscosity in the viscosity range from 1 to 8.4 cP. The quality factor (Q-factor) for the 50% glycerol/water mixture was determined to be greater than 20 for both the (1,1) and the (2,2) modes, indicating that the microdiaphragm resonating sensor is suitable for measuring the density and viscosity of a liquid within a density range from 0.998 to 1.1466 × 103 kg/m3 and a viscosity range from 1 to 8.4 cP. These density and viscosity ranges span the regime of possible changes of blood characteristics. The microdiaphragm resonating sensors were also tested with a real human serum to verify that the sensor is suitable for measuring the viscosity and density of blood. Therefore, the PZT microdiaphragm resonating sensor could be utilized for early diagnosis of diseases associated with changes in the physical properties of blood.

  12. Analysis of multi-layered films. [determining dye densities by applying a regression analysis to the spectral response of the composite transparency

    NASA Technical Reports Server (NTRS)

    Scarpace, F. L.; Voss, A. W.

    1973-01-01

    Dye densities of multi-layered films are determined by applying a regression analysis to the spectral response of the composite transparency. The amount of dye in each layer is determined by fitting the sum of the individual dye layer densities to the measured dye densities. From this, dye content constants are calculated. Methods of calculating equivalent exposures are discussed. Equivalent exposures are a constant amount of energy over a limited band-width that will give the same dye content constants as the real incident energy. Methods of using these equivalent exposures for analysis of photographic data are presented.

  13. Locating interfaces in vertically-layered materials and determining concentrations in mixed materials utilizing acoustic impedance measurements

    DOEpatents

    Langlois, G.N.

    1983-09-13

    Measurement of the relative and actual value of acoustic characteristic impedances of an unknown substance, location of the interfaces of vertically-layered materials, and the determination of the concentration of a first material mixed in a second material are disclosed. A highly damped ultrasonic pulse is transmitted into one side of a reference plate, such as a tank wall, where the other side of the reference plate is in physical contact with the medium to be measured. The amplitude of a return signal, which is the reflection of the transmitted pulse from the interface between the other side of the reference plate and the medium, is measured. The amplitude value indicates the acoustic characteristic impedance of the substance relative to that of the reference plate or relative to that of other tested materials. Discontinuities in amplitude with repeated measurements for various heights indicate the location of interfaces in vertically-layered materials. Standardization techniques permit the relative acoustic characteristic impedance of a substance to be converted to an actual value. Calibration techniques for mixtures permit the amplitude to be converted to the concentration of a first material mixed in a second material. 6 figs.

  14. Locating interfaces in vertically-layered materials and determining concentrations in mixed materials utilizing acoustic impedance measurements

    DOEpatents

    Langlois, Gary N.

    1983-09-13

    Measurement of the relative and actual value of acoustic characteristic impedances of an unknown substance, location of the interfaces of vertically-layered materials, and the determination of the concentration of a first material mixed in a second material. A highly damped ultrasonic pulse is transmitted into one side of a reference plate, such as a tank wall, where the other side of the reference plate is in physical contact with the medium to be measured. The amplitude of a return signal, which is the reflection of the transmitted pulse from the interface between the other side of the reference plate and the medium, is measured. The amplitude value indicates the acoustic characteristic impedance of the substance relative to that of the reference plate or relative to that of other tested materials. Discontinuities in amplitude with repeated measurements for various heights indicate the location of interfaces in vertically-layered materials. Standardization techniques permit the relative acoustic characteristic impedance of a substance to be converted to an actual value. Calibration techniques for mixtures permit the amplitude to be converted to the concentration of a first material mixed in a second material.

  15. Determination of mercury in river water by diffusive gradients in thin films using P81 membrane as binding layer.

    PubMed

    Colaço, Camila Destro; Yabuki, Lauren Nozomi Marques; Rolisola, Ana Marta; Menegário, Amauri Antonio; de Almeida, Eduardo; Suárez, Carlos Alfredo; Gao, Yue; Corns, Warren T; do Nascimento Filho, Virgílio Franco

    2014-11-01

    In this work, a device based on diffusive gradients in thin films (DGT) was evaluated for the determination of Hg(II) in river water. The DGT device was assembled with a cellulose phosphate ion exchange membrane (P81 Whatman) as a binding phase and agarose gel 1.5% (m/v) as a diffusive layer. Laboratory deployments showed that the binding of Hg(2+) ([Hg(DGT)]/[Hg(solution)]) by P81 membrane was more effective (97%) than the Chelex 100 resin (80%).The effect of ionic strength, pH and potential interfering ions on Hg binding with DGT׳s was investigated. The results showed no significant effect on the binding of Hg(II) at pH range from 3.5 to 8.5 and at an ionic strength range from 0.0005 to 0.1 mol L(-1). Uptakes of 50 µg L(-1) Hg(II) by P81 membrane were not affected by Fe, Mn, Zn, Cu, Ca and Mg at the concentration range of 200-1800 µg L(-1). Finally, the DGT device using the P81 as the binding layer was applied for in situ measurements of Hg in river water. For in situ measurements, the labile Hg concentration (from <2 to 13 ng L(-1)) was lower than 10% of the dissolved fraction (from 155 to 446 ng L(-1)). PMID:25127614

  16. Locating interfaces in vertically-layered materials and determining concentrations in mixed materials utilizing acoustic-impedance measurements. [Patent application

    DOEpatents

    Not Available

    1981-06-10

    Measurement of the relative and actual value of acoustic characteristic impedances of an unknown substance, location of the interfaces of vertically-layered materials, and the determination of the concentration of a first material mixed in a second material are presented. A highly damped ultrasonic pulse is transmitted into one side of a reference plate, such as a tank wall, where the other side of the reference plate is in physical contact with the medium to be measured. The amplitude of a return signal, which is the reflection of the transmitted pulse from the interface between the other side of the reference plate and the medium, is measured. The amplitude value indicates the acoustic characteristic impedance of the substance relative to that of the reference plate or relative to that of other tested materials. Discontinuities in amplitude with repeated measurements for various heights indicate the location of interfaces in vertically-layered materials. Standardization techniques permit the relative acoustic characteristic impedance of a substance to be converted to an actual value. Calibration techniques for mixtures permit the amplitude to be converted to the concentration of a first material mixed in a second material.

  17. Structure of lipid bilayers

    PubMed Central

    Nagle, John F.; Tristram-Nagle, Stephanie

    2009-01-01

    The quantitative experimental uncertainty in the structure of fully hydrated, biologically relevant, fluid (Lα) phase lipid bilayers has been too large to provide a firm base for applications or for comparison with simulations. Many structural methods are reviewed including modern liquid crystallography of lipid bilayers that deals with the fully developed undulation fluctuations that occur in the Lα phase. These fluctuations degrade the higher order diffraction data in a way that, if unrecognized, leads to erroneous conclusions regarding bilayer structure. Diffraction measurements at high instrumental resolution provide a measure of these fluctuations. In addition to providing better structural determination, this opens a new window on interactions between bilayers, so the experimental determination of interbilayer interaction parameters is reviewed briefly. We introduce a new structural correction based on fluctuations that has not been included in any previous studies. Updated measurements, such as for the area compressibility modulus, are used to provide adjustments to many of the literature values of structural quantities. Since the gel (Lβ′) phase is valuable as a stepping stone for obtaining fluid phase results, a brief review is given of the lower temperature phases. The uncertainty in structural results for lipid bilayers is being reduced and best current values are provided for bilayers of five lipids. PMID:11063882

  18. Employing X-ray Photoelectron Spectroscopy for Determining Layer Homogeneity in Mixed Polar Self-Assembled Monolayers.

    PubMed

    Hehn, Iris; Schuster, Swen; Wächter, Tobias; Abu-Husein, Tarek; Terfort, Andreas; Zharnikov, Michael; Zojer, Egbert

    2016-08-01

    Self-assembled monolayers (SAMs) containing embedded dipolar groups offer the particular advantage of changing the electronic properties of a surface without affecting the SAM-ambient interface. Here we show that such systems can also be used for continuously tuning metal work functions by growing mixed monolayers consisting of molecules with different orientations of the embedded dipolar groups. To avoid injection hot-spots when using the SAM-modified electrodes in devices, a homogeneous mixing of the two components is crucial. We show that a combination of high-resolution X-ray photoelectron spectroscopy with state-of-the-art simulations is an ideal tool for probing the electrostatic homogeneity of the layers and thus for determining phase separation processes in polar adsorbate assemblies down to inhomogeneities at the molecular level. PMID:27429041

  19. Development and validation of a high performance thin layer chromatographic method for determination of 1, 8-Cineole in Callistemon Citrinus.

    PubMed

    Shaha, Archana; Salunkhe, Vijay R

    2014-04-01

    A new, simple, precise, rapid, and selective high performance thin layer chromatographic (HPTLC) method has been developed and validated for the estimation of 1, 8-cineole in volatile oil of leaves of Callistemon Citrinus obtained by hydro distillation. The method was validated as per ICH guidelines and can be utilized for routine analysis. The retention factor for 1, 8-cineole was found to be 0.52. The linearity was found to be in the range of 3 μg-12 μg. The recovery obtained for 1, 8-cineole was 98%, which is satisfactory. The result obtained in validation indicate the accuracy, reproducibility, and reliability of the developed HPTLC method for determination of 1, 8-cineole. PMID:24761119

  20. Development and validation of a high performance thin layer chromatographic method for determination of 1, 8-Cineole in Callistemon Citrinus

    PubMed Central

    Shaha, Archana; Salunkhe, Vijay R

    2014-01-01

    A new, simple, precise, rapid, and selective high performance thin layer chromatographic (HPTLC) method has been developed and validated for the estimation of 1, 8-cineole in volatile oil of leaves of Callistemon Citrinus obtained by hydro distillation. The method was validated as per ICH guidelines and can be utilized for routine analysis. The retention factor for 1, 8-cineole was found to be 0.52. The linearity was found to be in the range of 3 μg-12 μg. The recovery obtained for 1, 8-cineole was 98%, which is satisfactory. The result obtained in validation indicate the accuracy, reproducibility, and reliability of the developed HPTLC method for determination of 1, 8-cineole. PMID:24761119

  1. Employing X-ray Photoelectron Spectroscopy for Determining Layer Homogeneity in Mixed Polar Self-Assembled Monolayers

    PubMed Central

    2016-01-01

    Self-assembled monolayers (SAMs) containing embedded dipolar groups offer the particular advantage of changing the electronic properties of a surface without affecting the SAM–ambient interface. Here we show that such systems can also be used for continuously tuning metal work functions by growing mixed monolayers consisting of molecules with different orientations of the embedded dipolar groups. To avoid injection hot-spots when using the SAM-modified electrodes in devices, a homogeneous mixing of the two components is crucial. We show that a combination of high-resolution X-ray photoelectron spectroscopy with state-of-the-art simulations is an ideal tool for probing the electrostatic homogeneity of the layers and thus for determining phase separation processes in polar adsorbate assemblies down to inhomogeneities at the molecular level. PMID:27429041

  2. Conformational flexibility in the apolipoprotein E amino-terminal domain structure determined from three new crystal forms: implications for lipid binding.

    PubMed Central

    Segelke, B. W.; Forstner, M.; Knapp, M.; Trakhanov, S. D.; Parkin, S.; Newhouse, Y. M.; Bellamy, H. D.; Weisgraber, K. H.; Rupp, B.

    2000-01-01

    An amino-terminal fragment of human apolipoprotein E3 (residues 1-165) has been expressed and crystallized in three different crystal forms under similar crystallization conditions. One crystal form has nearly identical cell dimensions to the previously reported orthorhombic (P2(1)2(1)2(1)) crystal form of the amino-terminal 22 kDa fragment of apolipoprotein E (residues 1-191). A second orthorhombic crystal form (P2(1)2(1)2(1) with cell dimensions differing from the first form) and a trigonal (P3(1)21) crystal form were also characterized. The structures of the first orthorhombic and the trigonal form were determined by seleno-methionine multiwavelength anomalous dispersion, and the structure of the second orthorhombic form was determined by molecular replacement using the structure from the trigonal form as a search model. A combination of modern experimental and computational techniques provided high-quality electron-density maps, which revealed new features of the apolipoprotein E structure, including an unambiguously traced loop connecting helices 2 and 3 in the four-helix bundle and a number of multiconformation side chains. The three crystal forms contain a common intermolecular, antiparallel packing arrangement. The electrostatic complimentarity observed in this antiparallel packing resembles the interaction of apolipoprotein E with the monoclonal antibody 2E8 and the low density lipoprotein receptor. Superposition of the model structures from all three crystal forms reveals flexibility and pronounced kinks in helices near one end of the four-helix bundle. This mobility at one end of the molecule provides new insights into the structural changes in apolipoprotein E that occur with lipid association. PMID:10850798

  3. Determining the Origin and Fate of Particulate Plant-Derived Organic Matter in the Rhone River (France) : A Lipid Tracer Review

    NASA Astrophysics Data System (ADS)

    Galeron, M. A.; Amiraux, R.; Charriere, B.; Radakovitch, O.; Raimbault, P.; Garcia, N.; Lagadec, V.; Vaultier, F.; Rontani, J. F.

    2014-12-01

    A number of lipid tracers including fatty acids, hydroxyacids, n-alkanols, sterols and triterpenoids were used to determine the origin and fate of suspended particulate organic matter (POM) collected in the Rhone River (France), with a main focus on phytosterols, such as sitosterol, desmosterol, brassicasterol and cholesterol. This seasonal survey (April 2011 to May 2013) revealed a year-round strong terrigenous contribution to the plant derived particulate organic matter (POM) with significant algal inputs observed in March and attributed to phytoplanktonic blooms likely dominated by diatoms. Specific sitosterol and cholesterol degradation products were quantified and used to estimate the part of biotic and abiotic degradation of POM within the river. Plant-derived organic matter appears to be mainly affected by photo-oxidation and autoxidation (free radical oxidation), while organic matter of human origin, evidenced by the presence of coprostanol, is clearly more prone to bacterial degradation. Despite the involvement of an intense autoxidation inducing homolytic cleavage of peroxy bonds, a significant proportion of hydroperoxides is still intact in higher plant debris. These compounds could play a role in the degradation of terrestrial material by inducing an intense autoxidation upon its arrival at sea. Although sitosterol has been commonly used as a tracer of the terrestrial origin of POM in rivers, we show here that is it also found in phytoplankton, which highlights the need to use different tracers to determine the origin of POM in rivers. As part of the set of tracers we use, we have identified betulin to be an interesting candidate, although limited to a number of angiosperms species. Not only can we trace betulin to an unequivocal terrestrial origin, we also identified its specific degradation products, allowing us to trace the degradation state of angiosperm particulate debris in rivers, as well as the type of degradation undergone.

  4. Estimation of intradermal disposition kinetics of drugs: II. Factors determining penetration of drugs from viable skin to muscular layer.

    PubMed

    Higaki, Kazutaka; Asai, Masahide; Suyama, Takayuki; Nakayama, Kazuki; Ogawara, Ken-ichi; Kimura, Toshikiro

    2002-06-01

    To develop a more efficient transdermal delivery system, it is very important to regulate the intradermal disposition of drugs after topical application. We tried to elucidate the factors determining the intradermal disposition kinetics, especially drug penetration from the viable skin to the muscular layer, mainly based on the six-compartment model, including the contralateral skin and muscle for ten model drugs with different physicochemical characteristics. In vivo transdermal absorption study was performed for six model drugs using the stripped-skin rats. The fitting analyses by the six-compartment model gave the theoretical curves describing the observed data very well and the reasonable pharmacokinetic parameters, showing the pharmacokinetic model should be useful for the estimation of the intradermal disposition kinetics of drugs applied topically again. The simulation study using the pharmacokinetic parameters obtained above could show the relative contribution of the direct penetration and the distribution from the systemic circulation to the muscular distribution of drugs. The largest contribution of direct penetration was observed for antipyrine (90.8%) and the smallest was for felbinac (43.3%). Among the pharmacokinetic parameters obtained above, the clearance from the viable skin to the muscle (CL(vs-m)) was found to be significantly correlated with the unbound fraction of drugs in the viable skin (fu(vs)). Although the clearance from the viable skin to the plasma (CL(vs-p)) also tended to increase as fu(vs) increased, the ratio of CL(vs-m) to CL(vs-p) was significantly correlated with fu(vs), meaning that the larger amount of unbound drug in the viable skin significantly contributes to the direct penetration into the muscle more than to the systemic absorption. On the other hand, k(direct) values obtained in in vitro penetration study-the penetration rate constant of drugs from the viable skin to the muscular layer-were found to be correlated with CL

  5. Using SANS with Contrast-Matched Lipid Bicontinuous Cubic Phases To Determine the Location of Encapsulated Peptides, Proteins, and Other Biomolecules.

    PubMed

    van 't Hag, Leonie; de Campo, Liliana; Garvey, Christopher J; Feast, George C; Leung, Anna E; Yepuri, Nageshwar Rao; Knott, Robert; Greaves, Tamar L; Tran, Nhiem; Gras, Sally L; Drummond, Calum J; Conn, Charlotte E

    2016-07-21

    An understanding of the location of peptides, proteins, and other biomolecules within the bicontinuous cubic phase is crucial for understanding and evolving biological and biomedical applications of these hybrid biomolecule-lipid materials, including during in meso crystallization and drug delivery. While theoretical modeling has indicated that proteins and additive lipids might phase separate locally and adopt a preferred location in the cubic phase, this has never been experimentally confirmed. We have demonstrated that perfectly contrast-matched cubic phases in D2O can be studied using small-angle neutron scattering by mixing fully deuterated and hydrogenated lipid at an appropriate ratio. The model transmembrane peptide WALP21 showed no preferential location in the membrane of the diamond cubic phase of phytanoyl monoethanolamide and was not incorporated in the gyroid cubic phase. While deuteration had a small effect on the phase behavior of the cubic phase forming lipids, the changes did not significantly affect our results. PMID:27414483

  6. Hen egg yolk lipid fractions with antiatherogenic properties.

    PubMed

    Nasopoulou, Constantina; Gogaki, Vassiliki; Panagopoulou, Eleanna; Demopoulos, Constantinos; Zabetakis, Ioannis

    2013-03-01

    Three different types of hen egg yolk, cage-free, organic and daily fresh, were tested for their antiatherogenic properties. Total lipids (TL) of all hen egg yolk samples were extracted by the method of Bligh and Dyer and further separated into total polar lipids (TPL) and total neutral lipids (TNL) by counter current distribution chromatography. TPL and TNL were further separated by preparative thin-layer chromatography (TLC). TL, TPL, TNL and the obtained polar and neutral lipid fractions after TLC separation were tested to determine whether they induce platelet activation or inhibit platelet activating factor (PAF)-induced platelet activation. All three hen egg yolk TL samples possessed strong inhibitory activity against PAF-induced platelet activation that was mainly attributed to TPL, especially to PL fraction 4. Cage-free hen egg yolk exhibited the most potent anti-PAF activity in all lipid classes (TL, TPL and TNL). Thus hen egg yolk contains PAF inhibitors that reinforce their nutritional value in terms of protection against cardiovascular diseases, since PAF is a crucial inflammatory phospholipid mediator that is implicated in the mechanism of atherogenesis. PMID:23480708

  7. Determining layer number of two-dimensional flakes of transition-metal dichalcogenides by the Raman intensity from substrates.

    PubMed

    Li, Xiao-Li; Qiao, Xiao-Fen; Han, Wen-Peng; Zhang, Xin; Tan, Qing-Hai; Chen, Tao; Tan, Ping-Heng

    2016-04-01

    Transition-metal dichalcogenide (TMD) semiconductors have been widely studied due to their distinctive electronic and optical properties. The property of TMD flakes is a function of their thickness, or layer number (N). How to determine the N of ultrathin TMD materials is of primary importance for fundamental study and practical applications. Raman mode intensity from substrates has been used to identify the N of intrinsic and defective multilayer graphenes up to N = 100. However, such analysis is not applicable to ultrathin TMD flakes due to the lack of a unified complex refractive index (ñ) from monolayer to bulk TMDs. Here, we discuss the N identification of TMD flakes on the SiO2/Si substrate by the intensity ratio between the Si peak from 100 nm (or 89 nm) SiO2/Si substrates underneath TMD flakes and that from bare SiO2/Si substrates. We assume the real part of ñ of TMD flakes as that of monolayer TMD and treat the imaginary part of ñ as a fitting parameter to fit the experimental intensity ratio. An empirical ñ, namely, ñ(eff), of ultrathin MoS2, WS2 and WSe2 flakes from monolayer to multilayer is obtained for typical laser excitations (2.54 eV, 2.34 eV or 2.09 eV). The fitted ñ(eff) of MoS2 has been used to identify the N of MoS2 flakes deposited on 302 nm SiO2/Si substrate, which agrees well with that determined from their shear and layer-breathing modes. This technique of measuring Raman intensity from the substrate can be extended to identify the N of ultrathin 2D flakes with N-dependent ñ. For application purposes, the intensity ratio excited by specific laser excitations has been provided for MoS2, WS2 and WSe2 flakes and multilayer graphene flakes deposited on Si substrates covered by a 80-110 nm or 280-310 nm SiO2 layer. PMID:26906625

  8. The “Beta-Clasp” model of apolipoprotein A-I - a lipid-free solution structure determined by electron paramagnetic resonance spectroscopy

    PubMed Central

    Lagerstedt, Jens O.; Budamagunta, Madhu S.; Liu, Grace S.; DeValle, Nicole C.; Voss, John C.; Oda, Michael N.

    2012-01-01

    Apolipoprotein A-I (apoA-I) is the major protein component of high density lipoproteins (HDL) and plays a central role in cholesterol metabolism. The lipid-free / lipid-poor form of apoA-I is the preferred substrate for the ATP-binding cassette transporter A1 (ABCA1). The interaction of apoA-I with ABCA1 leads to the formation of cholesterol laden high density lipoprotein (HDL) particles, a key step in reverse cholesterol transport and the maintenance of cholesterol homeostasis. Knowledge of the structure of lipid-free apoA-I is essential to understanding its critical interaction with ABCA1 and the molecular mechanisms underlying HDL biogenesis. We therefore examined the structure of lipid-free apoA-I by electron paramagnetic resonance spectroscopy (EPR). Through site directed spin label EPR, we mapped the secondary structure of apoA-I and identified sites of spin coupling as residues 26, 44, 64, 167, 217 and 226. We capitalize on the fact that lipid-free apoA-I self-associates in an anti-parallel manner in solution. We employed these sites of spin coupling to define the central plane in the dimeric apoA-I complex. Applying both the constraints of dipolar coupling with the EPR-derived pattern of solvent accessibility, we assembled the secondary structure into a tertiary context, providing a solution structure for lipid-free apoA-I. PMID:22245143

  9. Covalent attachment of functionalized lipid bilayers to planar waveguides for measuring protein binding to biomimetic membranes.

    PubMed Central

    Heyse, S.; Vogel, H.; Sänger, M.; Sigrist, H.

    1995-01-01

    A new method is presented for measuring sensitively the interactions between ligands and their membrane-bound receptors in situ using integrated optics, thus avoiding the need for additional labels. Phospholipid bilayers were attached covalently to waveguides by a novel protocol, which can in principle be used with any glass-like surface. In a first step, phospholipids carrying head-group thiols were covalently immobilized onto SiO2-TiO2 waveguide surfaces. This was accomplished by acylation of aminated waveguides with the heterobifunctional crosslinker N-succinimidyl-3-maleimidopropionate, followed by the formation of thioethers between the surface-grafted maleimides and the synthetic thiolipids. The surface-attached thiolipids served as hydrophobic templates and anchors for the deposition of a complete lipid bilayer either by fusion of lipid vesicles or by lipid self-assembly from mixed lipid/detergent micelles. The step-by-step lipid bilayer formation on the waveguide surface was monitored in situ by an integrated optics technique, allowing the simultaneous determination of optical thickness and one of the two refractive indices of the adsorbed organic layers. Surface coverages of 50-60% were calculated for thiolipid layers. Subsequent deposition of POPC resulted in an overall lipid layer thickness of 45-50 A, which corresponds to the thickness of a fluid bilayer membrane. Specific recognition reactions occurring at cell membrane surfaces were modeled by the incorporation of lipid-anchored receptor molecules into the supported bilayer membranes. (1) The outer POPC layer was doped with biotinylated phosphatidylethanolamine. Subsequent specific binding of streptavidin was optically monitored. (2) A lipopeptide was incorporated in the outer POPC monolayer. Membrane binding of monoclonal antibodies, which were directed against the peptide moiety of the lipopeptide, was optically detected. The specific antibody binding correlated well with the lipopepitde

  10. Determination of 2-Aminoacetophenone in wine by high-performance thin-layer chromatography-fluorescence detection.

    PubMed

    Horlacher, Nora; Schwack, Wolfgang

    2016-02-01

    2-Aminoacetophenone (AAP) is closely correlated with the appearance of the sensory phenomenon of UTA ("untypical aging off-flavor") in wine. AAP analyses are generally performed by gas chromatography and mass selective detection (GC/MS), when AAP is extracted from wines by liquid-liquid, solid-liquid or solid phase microextraction. Here we present a rapid, selective and sensitive method for the determination of AAP in wine by high-performance thin-layer chromatography with fluorescence detection (HPTLC-FLD). As internal standard, 2-amino-4-methoxyacetophenone was used. Liquid-liquid extraction with t-butyl methyl ether was followed by a basic cleanup of the extracts, which were applied onto HPTLC amino plates developed with methylene chloride/toluene (7+3, v/v) as mobile phase. Dipping the dried plate into hexane-paraffin solution enhanced fluorescence that was scanned at 366/>400nm. Limits of detection and quantitation were determined to be 0.1 and 0.3μgL(-1) wine, respectively, while only AAP concentrations >0.5μgL(-1) result in UTA. Recoveries were near 100% for model, white, rosé and red wines. Thus, the HPTLC-FLD method enables the analysis of AAP in wines clearly below the odor thresholds and represents a rapid and convenient screening alternative to existing GC/MS methods. PMID:26777086

  11. Determination of neomycin in the form of neomycin derivative with dabsyl chloride by thin layer chromatography and densitometry.

    PubMed

    Hubicka, Urszula; Zuromska-Witek, Barbara; Piotrowska, Joanna; Krzek, Jan

    2015-01-01

    A thin layer chromatographic-densitometric method has been developed for identification and quantitative determination of neomycin derivative with dabsyl chloride. The analysis of antibiotic was achieved on the silica gel TLC plates with fluorescent indicator with n-butanol--2-butanone--25% ammonia--water (10 : 6 : 2 : 2, v/v/v/v) as the mobile phase. The densitometric measurements were made at 460 nm. Under these conditions good separation of chosen aminoglycoside antibiotic from reagent used to make a complex was obtained. The method is characterized by high sensitivity, LOD from 0.1953 μg per band and LOQ from 0.5918 μg per band, wide linearity range from 0.5918 to 2.1960 μg per band for neomycin. The precision of the method was good; RSD varied from 1.17 to 2.05%. Satisfactory results of validation of the method were also confirmed by determination of selected antibiotic in pharmaceutical commercial preparation. The results obtained by TLC-densitometric method were compared with those obtained by spectrophotometric method. PMID:25850198

  12. Mechanisms of lipid regulation and lipid gating in TRPC channels.

    PubMed

    Svobodova, Barbora; Groschner, Klaus

    2016-06-01

    TRPC proteins form cation channels that integrate and relay cellular signals by mechanisms involving lipid recognition and lipid-dependent gating. The lipohilic/amphiphilic molecules that function as cellular activators or modulators of TRPC proteins span a wide range of chemical structures. In this context, cellular redox balance is likely linked to the lipid recognition/gating features of TRPC channels. Both classical ligand-protein interactions as well as indirect and promiscuous sensory mechanisms have been proposed. Some of the recognition processes are suggested to involve ancillary lipid-binding scaffolds or regulators as well as dynamic protein-protein interactions determined by bilayer architecture. A complex interplay of protein-protein and protein-lipid interactions is likely to govern the gating and/or plasma membrane recruitment of TRPC channels, thereby providing a distinguished platform for signal integration and coincident signal detection. Both the primary molecular event(s) of lipid recognition by TRPC channels as well as the transformation of these events into distinct gating movements is poorly understood at the molecular level, and it remains elusive whether lipid sensing in TRPCs is conferred to a distinct sensor domain. Recent structural information on the molecular action of lipophilic activators in distantly related members of the TRP superfamily encourages speculations on TRPC gating mechanisms involved in lipid recognition/gating. This review aims to provide an update on the current understanding of the lipid-dependent control of TRPC channels with focus on the TRPC lipid sensing, signal-integration hub and a short discussion of potential links to redox signaling. PMID:27125985

  13. Layer-by-layer cell membrane assembly

    NASA Astrophysics Data System (ADS)

    Matosevic, Sandro; Paegel, Brian M.

    2013-11-01

    Eukaryotic subcellular membrane systems, such as the nuclear envelope or endoplasmic reticulum, present a rich array of architecturally and compositionally complex supramolecular targets that are as yet inaccessible. Here we describe layer-by-layer phospholipid membrane assembly on microfluidic droplets, a route to structures with defined compositional asymmetry and lamellarity. Starting with phospholipid-stabilized water-in-oil droplets trapped in a static droplet array, lipid monolayer deposition proceeds as oil/water-phase boundaries pass over the droplets. Unilamellar vesicles assembled layer-by-layer support functional insertion both of purified and of in situ expressed membrane proteins. Synthesis and chemical probing of asymmetric unilamellar and double-bilayer vesicles demonstrate the programmability of both membrane lamellarity and lipid-leaflet composition during assembly. The immobilized vesicle arrays are a pragmatic experimental platform for biophysical studies of membranes and their associated proteins, particularly complexes that assemble and function in multilamellar contexts in vivo.

  14. Intercalation of small hydrophobic molecules in lipid bilayers containing cholesterol

    SciTech Connect

    Worcester, D.L.; Hamacher, K.; Kaiser, H.; Kulasekere, R.; Torbet, J.

    1994-12-31

    Partitioning of small hydrophobic molecules into lipid bilayers containing cholesterol has been studied using the 2XC diffractometer at the University of Missouri Research Reactor. Locations of the compounds were determined by Fourier difference methods with data from both deuterated and undeuterated compounds introduced into the bilayers from the vapor phase. Data fitting procedures were developed for determining how well the compounds were localized. The compounds were found to be localized in a narrow region at the center of the hydrophobic layer, between the two halves of the bilayer. The structures are therefore intercalated structures with the long axis of the molecules in the plane of the bilayer.

  15. Intercalation of small hydrophobic molecules in lipid bilayers containing cholesterol.

    PubMed

    Worcester, D L; Hamacher, K; Kaiser, H; Kulasekere, R; Torbet, J

    1996-01-01

    Partitioning of small hydrophobic molecules into lipid bilayers containing cholesterol has been studied using the 2XC diffractometer at the University of Missouri Research Reactor. Locations of the compounds were determined by Fourier difference methods with data from both deuterated and undeuterated compounds introduced into the bilayers from the vapor phase. Data fitting procedures were developed for determining how well the compounds were localized. The compounds were found to be localized in a narrow region at the center of the hydrophobic layer, between the two halves of the bilayer. The structures are therefore intercalated structures with the long axis of the molecules in the plane of the bilayer. PMID:9031514

  16. A Simple Method for Determining Heat Transfer, Skin Friction, and Boundary-Layer Thickness for Hypersonic Laminar Boundary-Layer Flows in a Pressure Gradient

    NASA Technical Reports Server (NTRS)

    Bertram, Mitchel H.; Feller, William V.

    1959-01-01

    A procedure based on the method of similar solutions is presented by which the skin friction, heat transfer, and boundary-layer thickness in a laminar hypersonic flow with pressure gradient may be rapidly evaluated if the pressure distribution is known. This solution, which at present is. restricted to power-law variations of pressure with surface distance, is presented for a wide range of exponents in the power law corresponding to both favorable and adverse pressure gradients. This theory has been compared to results from heat-transfer experiments on blunt-nose flat plates and a hemisphere cylinder at free-stream Mach numbers of 4 and 6.8. The flat-plate experiments included tests made at a Mach number of 6.8 over a range of angle of attack of +/- 10 deg. Reasonable agreement of the experimental and theoretical heat-transfer coefficients has been obtained as well as good correlation of the experimental results over the entire range of angle of attack studied. A similar comparison of theory with experiment was not feasible for boundary-layer-thickness data; however, the hypersonic similarity theory was found to account satisfactorily for the variation in boundary-layer thickness due to local pressure distribution for several sets of measurements.

  17. Changes Caused by Fruit Extracts in the Lipid Phase of Biological and Model Membranes

    PubMed Central

    Pruchnik, Hanna; Oszmiański, Jan; Sarapuk, Janusz; Kleszczyńska, Halina

    2010-01-01

    The aim of the study was to determine changes incurred by polyphenolic compounds from selected fruits in the lipid phase of the erythrocyte membrane, in liposomes formed of erythrocyte lipids and phosphatidylcholine liposomes. In particular, the effect of extracts from apple, chokeberry, and strawberry on the red blood cell morphology, on packing order in the lipid hydrophilic phase, on fluidity of the hydrophobic phase, as well as on the temperature of phase transition in DPPC liposomes was studied. In the erythrocyte population, the proportions of echinocytes increased due to incorporation of polyphenolic compounds. Fluorimetry with a laurdan probe indicated increased packing density in the hydrophilic phase of the membrane in presence of polyphenolic extracts, the highest effect being observed for the apple extract. Using the fluorescence probes DPH and TMA-DPH, no effect was noted inside the hydrophobic phase of the membrane, as the lipid bilayer fluidity was not modified. The polyphenolic extracts slightly lowered the phase transition temperature of phosphatidylcholine liposomes. The studies have shown that the phenolic compounds contained in the extracts incorporate into the outer region of the erythrocyte membrane, affecting its shape and lipid packing order, which is reflected in the increasing number of echinocytes. The compounds also penetrate the outer part of the external lipid layer of liposomes formed of natural and DPPC lipids, changing its packing order. PMID:21423329

  18. Molecular interaction of a new antibacterial polymer with a supported lipid bilayer measured by an in situ label-free optical technique.

    PubMed

    Horvath, Robert; Kobzi, Balázs; Keul, Helmut; Moeller, Martin; Kiss, Eva

    2013-01-01

    The interaction of the antibacterial polymer-branched poly(ethylene imine) substituted with quaternary ammonium groups, PEO and alkyl chains, PEI25QI5J5A815-with a solid supported lipid bilayer was investigated using surface sensitive optical waveguide spectroscopy. The analysis of the optogeometrical parameters was extended developing a new composite layer model in which the structural and optical anisotropy of the molecular layers was taken into consideration. Following in situ the change of optical birefringence we were able to determine the composition of the lipid/polymer surface layer as well as the displacement of lipid bilayer by the antibacterial polymer without using additional labeling. Comparative assessment of the data of layer thickness and optical anisotropy helps to reveal the molecular mechanism of antibacterial effect of the polymer investigated. PMID:23648479

  19. Determination of cortisol in human plasma by thin-layer chromatography and fluorescence derivatization with isonicotinic acid hydrazide.

    PubMed

    Fenske, Martin

    2008-01-01

    The present work describes a specific and rapid determination of cortisol in human plasma. The method includes liquid-liquid extraction of plasma samples, thin-layer chromatography (TLC) of ethanolic extracts on aluminium foil-backed silica gel 60 TLC plates, derivatization of cortisol with isonicotinic acid hydrazide, and densitometric measurement of the fluorescence intensity of cortisol hydrazone. The fluorescence was linearly related to cortisol amounts; the correlation coefficients of standard curve plots were r>0.99. The coefficient of variation ranged between 2.8-7.9% (20 ng, within-assay/between assay variation) and 1.6-6.8% (80 ng, within-assay/between assay variation). The recovery of cortisol from plasma spiked with 21-deoxycortisol was 85%+/-4%. Cortisol concentration in the plasma was 66+/-32 ng/mL (mean+/-standard deviation, n=24). The advantage of this method is its simplicity to separate cortisol from other steroids by TLC, its specificity (formation of cortisol hydrazone), and the rapid quantitation of cortisol by densitometry. PMID:18218180

  20. Determination and Pharmacokinetic Study of Pirfenidone in Rat Serum by High-Performance Thin-Layer Chromatography.

    PubMed

    Thorat, Sonali G; Chikhale, Rupesh V

    2016-08-01

    A rapid, sensitive and selective high-performance thin-layer chromatography (HPTLC) method was developed and validated for the determination and pharmacokinetics of pirfenidone in rat serum. One-step protein precipitation by methanol is reported, and serum samples were separated by HPTLC using a simple mobile phase of toluene-methanol in the ratio of 8:2. The retardation factor of pirfenidone in the serum sample was 0.45 with the detection performed at 315 nm. The calibration curve was linear over the range of 100-1,200 ng/spot with a lower limit of quantitation of 40 ng/spot. The mean recovery of pirfenidone in serum was in the range of 70.6-75.8%, and intra-day and inter-day precision were both <14.1%. This method was successfully applied to the pharmacokinetic study of pirfenidone in rats on oral administration of the drug at a dose of 15.0 mg/kg. PMID:27406123

  1. Determination of Planetary Boundary Layer Height from Ground Based Wind Profiler and Lidar Measurements using the Covariance Wavelet Transform (CWT)

    NASA Astrophysics Data System (ADS)

    Compton, Jaime Cole

    This thesis documents the application of the Covariance Wavelet Transform (CWT) to lidar and, for the first time to our knowledge, wind profiler data to examine the possibility of accurate and continuous planetary boundary layer height (PBLH) measurements on short temporal resolution (one and fifteen minute averages respectively). Comparisons between PBLHs derived from the Elastic Lidar Facility (ELF) through application of the CWT and daytime radiosonde launches from Beltsville and RFK Stadium as part of the September 2009 NOAA/ARL and NCEP field study show an R2 = 0.84 correlation. PBLHs from ELF aided in diagnosing issues with the automatic PBLH calculation from Aircraft Communications Addressing and Reporting System (ACARS) profiles in the Real-Time Mesoscale Analysis used by plume dispersion modelers. Determining the mixing in the PBL was one goal of a study of the spatial and diurnal variations of the PBL height over Maryland for July 2011, during NASA's Earth Venture mission DISCOVER-AQ. A semi-automated PBLH detection algorithm utilizing the CWT for wind profiler data was developed. This algorithm was tested on data from the 915 MHz wind profiler at Beltsville, Maryland, and compared against PBLHs derived from ground based radiosondes measured at Beltsville. Comparisons were also done between PBLHs derived from ground based lidars at UMBC and Beltsville. Results from the comparison show an R 2 = 0.89, 0.92, and 0.94 correlation between the radiosonde PBLHs and the lidars and wind profiler PBLHs, respectively. Accurate determination of the PBLH by applying the CWT to lidar and wind profilers will allow for improved air quality forecasting and understanding of regional pollution dynamics.

  2. Simultaneous Determination of Size and Quantification of Gold Nanoparticles by Direct Coupling Thin layer Chromatography with Catalyzed Luminol Chemiluminescence

    NASA Astrophysics Data System (ADS)

    Yan, Neng; Zhu, Zhenli; He, Dong; Jin, Lanlan; Zheng, Hongtao; Hu, Shenghong

    2016-04-01

    The increasing use of metal-based nanoparticle products has raised concerns in particular for the aquatic environment and thus the quantification of such nanomaterials released from products should be determined to assess their environmental risks. In this study, a simple, rapid and sensitive method for the determination of size and mass concentration of gold nanoparticles (AuNPs) in aqueous suspension was established by direct coupling of thin layer chromatography (TLC) with catalyzed luminol-H2O2 chemiluminescence (CL) detection. For this purpose, a moving stage was constructed to scan the chemiluminescence signal from TLC separated AuNPs. The proposed TLC-CL method allows the quantification of differently sized AuNPs (13 nm, 41 nm and 100 nm) contained in a mixture. Various experimental parameters affecting the characterization of AuNPs, such as the concentration of H2O2, the concentration and pH of the luminol solution, and the size of the spectrometer aperture were investigated. Under optimal conditions, the detection limits for AuNP size fractions of 13 nm, 41 nm and 100 nm were 38.4 μg L‑1, 35.9 μg L‑1 and 39.6 μg L‑1, with repeatabilities (RSD, n = 7) of 7.3%, 6.9% and 8.1% respectively for 10 mg L‑1 samples. The proposed method was successfully applied to the characterization of AuNP size and concentration in aqueous test samples.

  3. Simultaneous Determination of Size and Quantification of Gold Nanoparticles by Direct Coupling Thin layer Chromatography with Catalyzed Luminol Chemiluminescence

    PubMed Central

    Yan, Neng; Zhu, Zhenli; He, Dong; Jin, Lanlan; Zheng, Hongtao; Hu, Shenghong

    2016-01-01

    The increasing use of metal-based nanoparticle products has raised concerns in particular for the aquatic environment and thus the quantification of such nanomaterials released from products should be determined to assess their environmental risks. In this study, a simple, rapid and sensitive method for the determination of size and mass concentration of gold nanoparticles (AuNPs) in aqueous suspension was established by direct coupling of thin layer chromatography (TLC) with catalyzed luminol-H2O2 chemiluminescence (CL) detection. For this purpose, a moving stage was constructed to scan the chemiluminescence signal from TLC separated AuNPs. The proposed TLC-CL method allows the quantification of differently sized AuNPs (13 nm, 41 nm and 100 nm) contained in a mixture. Various experimental parameters affecting the characterization of AuNPs, such as the concentration of H2O2, the concentration and pH of the luminol solution, and the size of the spectrometer aperture were investigated. Under optimal conditions, the detection limits for AuNP size fractions of 13 nm, 41 nm and 100 nm were 38.4 μg L−1, 35.9 μg L−1 and 39.6 μg L−1, with repeatabilities (RSD, n = 7) of 7.3%, 6.9% and 8.1% respectively for 10 mg L−1 samples. The proposed method was successfully applied to the characterization of AuNP size and concentration in aqueous test samples. PMID:27080702

  4. Using radio-induced fluorescence to determine the horizontal structure of ion layers in the mesosphere and lower thermosphere

    NASA Astrophysics Data System (ADS)

    Bernhardt, Paul A.; Gondarenko, Natalia A.; Guzdar, Parvez N.; Huba, Joseph D.; Ossakow, S. L.; Djuth, Frank T.; Tepley, C. A.; Sulzer, Michael P.; Kagan, Ludmila; Kelley, M. C.

    2002-01-01

    Two-dimensional images of Sporadic-E layers have been produced using a new technique called radio induced fluorescence (RIF). This technique makes the ion layers glow when being stimulated by high power radio waves. Normally the ion-layers do not radiate visible emissions. Experiments on January 1998 at Arecibo Observatory in Puerto Rico have shown that the layers can be made to glow at 557.7 nm and other wavelengths by illuminating them with radio waves at 3.175 MHz with effective radiated powers of 80 megawatts. The regions of the sporadic-E layers that have electron densities greater than the critical density for reflection of the radio waves emit electrons that collide with and excite atmospheric atomic oxygen and molecular nitrogen. A charge-coupled-device (CCD) imager located on the ground is used to capture images of the glowing E-region structures. The camera exposure times were in the range of 15 to 45 seconds. The images obtained using this technique show a wide variety of structures in the sporadic-E layers. Some layers cover the 15 x 30 km region illuminated by the radio wave beam. Other layers show strong modulation of the E-region by neutral wind instabilities. Two-dimensional computer simulations of the coupling between neutral wind turbulence and the ion layers simulate the structure in the images.

  5. Iron silicide formation at different layers of (Fe/Si){sub 3} multilayered structures determined by conversion electron Mössbauer spectroscopy

    SciTech Connect

    Badía-Romano, L. Bartolomé, J.; Rubín, J.; Magén, C.; Bürgler, D. E.

    2014-07-14

    The morphology and the quantitative composition of the Fe-Si interface layer forming at each Fe layer of a (Fe/Si){sub 3} multilayer have been determined by means of conversion electron Mössbauer spectroscopy (CEMS) and high-resolution transmission electron microscopy (HRTEM). For the CEMS measurements, each layer was selected by depositing the Mössbauer active {sup 57}Fe isotope with 95% enrichment. Samples with Fe layers of nominal thickness d{sub Fe} = 2.6 nm and Si spacers of d{sub Si} = 1.5 nm were prepared by thermal evaporation onto a GaAs(001) substrate with an intermediate Ag(001) buffer layer. HRTEM images showed that Si layers grow amorphous and the epitaxial growth of the Fe is good only for the first deposited layer. The CEMS spectra show that at all Fe/Si and Si/Fe interfaces a paramagnetic c-Fe{sub 1−x}Si phase is formed, which contains 16% of the nominal Fe deposited in the Fe layer. The bottom Fe layer, which is in contact with the Ag buffer, also contains α-Fe and an Fe{sub 1−x}Si{sub x} alloy that cannot be attributed to a single phase. In contrast, the other two layers only comprise an Fe{sub 1−x}Si{sub x} alloy with a Si concentration of ≃0.15, but no α-Fe.

  6. Interactions in lipid stabilised foam films.

    PubMed

    Toca-Herrera, José Luis; Krasteva, Nadejda; Müller, Hans-Joachim; Krastev, Rumen

    2014-05-01

    The interaction between lipid bilayers in water has been intensively studied over the last decades. Osmotic stress was applied to evaluate the forces between two approaching lipid bilayers in aqueous solution. The force-distance relation between lipid mono- or bilayers deposited on mica sheets using a surface force apparatus (SFA) was also measured. Lipid stabilised foam films offer another possibility to study the interactions between lipid monolayers. These films can be prepared comparatively easy with very good reproducibility. Foam films consist usually of two adsorbed surfactant monolayers separated by a layer of the aqueous solution from which the film is created. Their thickness can be conveniently measured using microinterferometric techniques. Studies with foam films deliver valuable information on the interactions between lipid membranes and especially their stability and permeability. Presenting inverse black lipid membrane (BLM) foam films supply information about the properties of the lipid self-organisation in bilayers. The present paper summarises results on microscopic lipid stabilised foam films by measuring their thickness and contact angle. Most of the presented results concern foam films prepared from dispersions of the zwitterionic lipid 1,2-dimyristoyl-sn-glycero-3-phosphorylcholine (DMPC) and some of its mixtures with the anionic lipid -- 1,2-dimyristoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (DMPG). The strength of the long range and short range forces between the lipid layers is discussed. The van der Waals attractive force is calculated. The electrostatic repulsive force is estimated from experiments at different electrolyte concentrations (NaCl, CaCl₂) or by modification of the electrostatic double layer surface potential by incorporating charged lipids in the lipid monolayers. The short range interactions are studied and modified by using small carbohydrates (fructose and sucrose), ethanol (EtOH) or dimethylsulfoxide (DMSO). Some

  7. The physics of stratum corneum lipid membranes.

    PubMed

    Das, Chinmay; Olmsted, Peter D

    2016-07-28

    The stratum corneum (SC), the outermost layer of skin, comprises rigid corneocytes (keratin-filled dead cells) in a specialized lipid matrix. The continuous lipid matrix provides the main barrier against uncontrolled water loss and invasion of external pathogens. Unlike all other biological lipid membranes (such as intracellular organelles and plasma membranes), molecules in the SC lipid matrix show small hydrophilic groups and large variability in the length of the alkyl tails and in the numbers and positions of groups that are capable of forming hydrogen bonds. Molecular simulations provide a route for systematically probing the effects of each of these differences separately. In this article, we present the results from atomistic molecular dynamics of selected lipid bilayers and multi-layers to probe the effect of these polydispersities. We address the nature of the tail packing in the gel-like phase, the hydrogen bond network among head groups, the bending moduli expected for leaflets comprising SC lipids and the conformation of very long ceramide lipids in multi-bilayer lipid assemblies.This article is part of the themed issue 'Soft interfacial materials: from fundamentals to formulation'. PMID:27298438

  8. Dramatic role of fragility in determining the magnitude of Tg perturbations to ultrathin film layers and near-infinitely dilute blend components

    NASA Astrophysics Data System (ADS)

    Evans, Christopher; Torkelson, John; Northwestern University Team

    2013-03-01

    Using fluorescence, we measure the glass transition temperatures (Tg) of ultrathin (11-14 nm) polystyrene (PS, bulk Tg = 103 °C) layers which can be tuned over ~ 80 °C when sandwiched between two bulk neighboring layers of poly(4-vinyl pyridine) (P4VP), polycarbonate, poly(vinyl chloride) (PVC) or poly(tert-butyl acrylate). Between P4VP, an ultrathin PS layer has its dynamics slaved and reports the Tg of bulk P4VP. In contrast, an ultrathin PS layer is weakly perturbed (Tg = 97 °C) when placed between PVC. These perturbations to the PS Tg become evident even for layers 10s of nanometers in thickness. Additionally, binary blends were prepared with 0.1 wt% PS components surrounded by the same neighboring polymers as in the trilayers. The Tg reported by an ultrathin PS layer and a 0.1 wt% PS blend component are the same for a given polymer pair indicating that the Tg perturbations in these two systems arise from a common physical origin. The strength of perturbations to PS correlate with the fragility of the neighboring domain in both blends and multilayers indicating that it is a key variable in determining the strength of Tg-confinement effects. Fragility also tracks with the magnitude of Tg-confinement effects observed in single layer polymer films supported on silicon wafers.

  9. Thickness determination of few-layer hexagonal boron nitride films by scanning electron microscopy and Auger electron spectroscopy

    SciTech Connect

    Sutter, P. Sutter, E.

    2014-09-01

    We assess scanning electron microscopy (SEM) and Auger electron spectroscopy (AES) for thickness measurements on few-layer hexagonal boron nitride (h-BN), the layered dielectric of choice for integration with graphene and other two-dimensional materials. Observations on h-BN islands with large, atomically flat terraces show that the secondary electron intensity in SEM reflects monolayer height changes in films up to least 10 atomic layers thickness. From a quantitative analysis of AES data, the energy-dependent electron escape depth in h-BN films is deduced. The results show that AES is suitable for absolute thickness measurements of few-layer h-BN of 1 to 6 layers.

  10. Determination of Axial Length Requiring Adjustment of Measured Circumpapillary Retinal Nerve Fiber Layer Thickness for Ocular Magnification

    PubMed Central

    Hirasawa, Kazunori; Shoji, Nobuyuki; Yoshii, Yukako; Haraguchi, Shota

    2014-01-01

    Purpose To determine the axial length requiring adjustment of measured circumpapillary retinal nerve fiber layer (cpRNFL) thickness to account for ocular magnification during spectral-domain optical coherence tomography (SD-OCT). Methods In this prospective study, 148 eyes of 148 healthy student volunteers were imaged by two examiners using three-dimensional SD-OCT. In 54 randomly selected eyes, total cpRNFL thickness was measured with and without adjustment for ocular magnification to establish intra-examiner and inter-examiner measurement error. The 148 eyes were then divided into three groups according to the error values: control group (difference in the corrected and uncorrected total cpRNFL thickness was within the measurement error range), thinner group (the corrected total cpRNFL thickness was less than the uncorrected one), and thicker group (the corrected total cpRNFL thickness was more than the uncorrected one). The cutoff values of axial length between the control and the other groups were calculated by receiver operating characteristic analysis. Results Measurement error ranged from 4.2 to 5.3 µm; the threshold value was defined as 5.3 µm. The cutoff values of axial length between the thinner and the control groups and between the control and the thicker groups were 23.60 (area under the curve [AUC] = 0.959) and 25.55 (AUC = 0.944) mm, respectively. Conclusions Axial lengths shorter than 23.60 mm and longer than 25.55 mm require adjustment of measured cpRNFL thickness to account for ocular magnification during SD-OCT. Clinical Trial Registration UMIN Clinical Trials Registry (http://www.umin.ac.jp/) under unique trial number UMIN000013248 (date of registration: 02/24/2014) PMID:25215521

  11. A High-Performance Thin Layer Chromatography (HPTLC) Method for Simultaneous Determination of Diphenhydramine Hydrochloride and Naproxen Sodium in Tablets

    PubMed Central

    Bhole, R.P.; Shinde, S.S.; Chitlange, S.S.; Wankhede, S.B.

    2015-01-01

    A rapid and simple high-performance thin layer chromatography (HPTLC) method with densitometry at 230 nm was developed and validated for simultaneous determination of diphenhydramine hydrochloride (DPH) and naproxen sodium (NPS) from pharmaceutical preparation. The separation was carried out on aluminum plates precoated with silica gel 60 F254 using mobile phase toluene:methanol:glacial acetic acid (7.5:1:0.2, v/v/v). The linearity range lies between 200 and 1200 ng/band for DPH and 1760 and 10,560 ng/band for NPS with correlation coefficients of 0.994 and 0.995, respectively. The Rf value for DPH is 0.20 ± 0.05 and for NPS is 0.61 ± 0.06. % Recoveries of DPH and NPS was in the range of 99.70%–99.95% and 99.63%–99.95%, respectively. Limit of detection value for DPH was 13.21 ng/band and for NPS was 8.03 ng/band. Limit of quantitation value for DPH was 40.06 ng/band and for NPS was 24.34 ng/band. The developed method was validated as per ICH guidelines. In stability testing, DPH was found unstable to acid and alkaline hydrolysis, and DPH and NPS were found unstable to oxidation, whereas both the drugs were stable to neutral and photodegradation. The proposed method was successfully applied for the routine quantitative analysis of dosage form containing DPH and NPS. PMID:26692760

  12. A High-Performance Thin Layer Chromatography (HPTLC) Method for Simultaneous Determination of Diphenhydramine Hydrochloride and Naproxen Sodium in Tablets.

    PubMed

    Bhole, R P; Shinde, S S; Chitlange, S S; Wankhede, S B

    2015-01-01

    A rapid and simple high-performance thin layer chromatography (HPTLC) method with densitometry at 230 nm was developed and validated for simultaneous determination of diphenhydramine hydrochloride (DPH) and naproxen sodium (NPS) from pharmaceutical preparation. The separation was carried out on aluminum plates precoated with silica gel 60 F254 using mobile phase toluene:methanol:glacial acetic acid (7.5:1:0.2, v/v/v). The linearity range lies between 200 and 1200 ng/band for DPH and 1760 and 10,560 ng/band for NPS with correlation coefficients of 0.994 and 0.995, respectively. The R f value for DPH is 0.20 ± 0.05 and for NPS is 0.61 ± 0.06. % Recoveries of DPH and NPS was in the range of 99.70%-99.95% and 99.63%-99.95%, respectively. Limit of detection value for DPH was 13.21 ng/band and for NPS was 8.03 ng/band. Limit of quantitation value for DPH was 40.06 ng/band and for NPS was 24.34 ng/band. The developed method was validated as per ICH guidelines. In stability testing, DPH was found unstable to acid and alkaline hydrolysis, and DPH and NPS were found unstable to oxidation, whereas both the drugs were stable to neutral and photodegradation. The proposed method was successfully applied for the routine quantitative analysis of dosage form containing DPH and NPS. PMID:26692760

  13. Reducible cationic lipids for gene transfer.

    PubMed Central

    Wetzer, B; Byk, G; Frederic, M; Airiau, M; Blanche, F; Pitard, B; Scherman, D

    2001-01-01

    One of the main challenges of gene therapy remains the increase of gene delivery into eukaryotic cells. We tested whether intracellular DNA release, an essential step for gene transfer, could be facilitated by using reducible cationic DNA-delivery vectors. For this purpose, plasmid DNA was complexed with cationic lipids bearing a disulphide bond. This reduction-sensitive linker is expected to be reduced and cleaved in the reducing milieu of the cytoplasm, thus potentially improving DNA release and consequently transfection. The DNA--disulphide-lipid complexation was monitored by ethidium bromide exclusion, and the size of complexes was determined by dynamic light scattering. It was found that the reduction kinetics of disulphide groups in DNA--lipid complexes depended on the position of the disulphide linker within the lipid molecule. Furthermore, the internal structure of DNA--lipid particles was examined by small-angle X-ray scattering before and after lipid reduction. DNA release from lipid complexes was observed after the reduction of disulphide bonds of several lipids. Cell-transfection experiments suggested that complexes formed with selected reducible lipids resulted in up to 1000-fold higher reporter-gene activity, when compared with their analogues without disulphide bonds. In conclusion, reduction-sensitive groups introduced into cationic lipid backbones potentially allow enhanced DNA release from DNA--lipid complexes after intracellular reduction and represent a tool for improved vectorization. PMID:11389682

  14. Diversity of Lipid Distribution in Fish Skeletal Muscle.

    PubMed

    Kaneko, Gen; Shirakami, Hirohito; Hirano, Yuki; Oba, Moemi; Yoshinaga, Hazuki; Khieokhajonkhet, Anurak; Nagasaka, Reiko; Kondo, Hidehiro; Hirono, Ikuo; Ushio, Hideki

    2016-04-01

    Adipose tissue is a lipid storage organ characterized by the pronounced accumulation of adipocytes. Although adipose tissues are found in various parts of the vertebrate body, it is unclear whether these tissues have a common ancestral origin or have evolved in several phylogenetic lineages by independent adipocyte accumulation events. To gain insight into the evolutionary history of vertebrate adipose tissues, we determined the distribution of adipocytes by oil red O staining in skeletal muscle of 10 teleost species spanning eight orders: Tetraodontiformes, Pleuronectiformes, Spariformes, Salmoniformes, Clupeiformes, Beloniformes, Osmeriformes, and Cypriniformes. Accumulation of adipocytes in the myoseptum was observed in many species, including red seabream, rainbow trout, Pacific herring, Pacific saury, zebrafish and giant danio. We also found some order-, species-, and swimming mode-specific distribution patterns of adipocytes: 1) almost complete absence of intramuscular adipocytes in the order Tetraodontiformes (torafugu and spotted green pufferfish), 2) clear adipocyte accumulation in the inclinator muscles of fin in Japanese flounder, 3) a large intramuscular adipose tissue at the root of the dorsal fin in ayu, and 4) thick lipid layers consisting of subcutaneous adipose tissue and red muscle lipids in pelagic migratory fish (Pacific herring and Pacific saury). Of note, Pacific herring and Pacific saury are phylogenetically distinct species sharing a similar niche and swimming mode, suggesting that their analogous adipocyte/lipid distribution patterns are the consequence of convergent evolution. The potentially heterogeneous origin of adipose tissues has significant implications for the interpretation of their functional diversity. PMID:27032682

  15. Organization of lipids in avian stratum corneum: Changes with temperature and hydration.

    PubMed

    Champagne, Alex M; Allen, Heather C; Bautista-Jimenez, Robin C; Williams, Joseph B

    2016-02-01

    In response to increases in ambient temperature (Ta), many animals increase total evaporative water loss (TEWL) through their skin and respiratory passages to maintain a constant body temperature, a response that compromises water balance. In birds, cutaneous water loss (CWL) accounts for approximately 65% of TEWL at thermoneutral temperatures. Although the proportion of TEWL accounted for by CWL decreases to only 25% at high Ta, the magnitude of CWL still increases, suggesting changes in the barrier function of the skin. The stratum corneum (SC) is composed of flat, dead cells called corneocytes embedded in a matrix of lipids, many of which arrange in layers called lamellae. The classes of lipids that comprise these lamellae, and their attendant physical properties, determine the rate of CWL. We measured CWL at 25, 30, 35, and 40 °C in House Sparrows (Passer domesticus) caught in the winter and summer, and in sparrows acclimated to warm and cold lab environments. We then used Fourier transform infrared spectroscopy to measure lipid-lipid and lipid-water interactions in the SC under different conditions of temperature and hydration, and correlated these results with lipid classes in the SC. As CWL increased at higher temperatures, the amount of gauche defects in lipid alkyl chains increased, indicating that lipid disorder is partially responsible for higher CWL at high temperatures. However, variation in CWL between groups could not be explained by the amount of gauche defects, and this remaining variation may be attributed to greater amounts of cerebrosides in birds with low CWL, as the sugar moieties of cerebrosides lie outside lipid lamellae and form strong hydrogen bonds with water molecules. PMID:26708071

  16. Painted supported lipid membranes

    PubMed Central

    Florin, E.-L.; Gaub, H. E.

    1993-01-01

    We report herein measurements on a novel type of supported lipid films, which we call painted supported membranes (PSM). These membranes are formed in a self-assembly process on alkylated gold films from an organic solution. The formation process was investigated with surface plasmon resonance microscopy. The optical and electrical properties of the films were determined for various types of lipids and as a function of temperature by means of cyclic voltammetry and potential relaxation after charge injection. We could show that these films exhibit an extraordinarily high specific resistivity which, depending on the lipid, may be as high as 109 ohm/cm2. We could also show that due to this low conductivity, an electrical polarization across the PSM relaxes with characteristic time constants of up to 20 min. The electrical properties together with their high mechanical stability and accessibility to surface sensitive techniques make these films well suitable model membranes for optical and electrical investigations. Examples for such applications are given in the subsequent article by Seifert et al. ImagesFIGURE 3FIGURE 4 PMID:19431873

  17. Depth profiles of a shallow implanted layer in a Si wafer determined by different methods of thin-layer analysis1

    NASA Astrophysics Data System (ADS)

    Klockenkämper, R.; Becker, H. W.; Bubert, H.; Jenett, H.; von Bohlen, A.

    2002-10-01

    Several different methods of thin-layer analysis have been applied to depth profiling of the same sample on the nanometer scale: two variants of Monte Carlo simulations, X-ray photoelectron spectrometry (XPS) with sputtering, sputtered neutrals mass spectrometry (SNMS), grazing-incidence X-ray fluorescence (GI-XRF), Rutherford backscattering (RBS) and a newly developed method, i.e. a combination of wet-chemical etching and total-reflection X-ray fluorescence (TXRF). Depth profiles were recorded for a silicon wafer implanted with Co ions at a dose of 10 17 cm -2. For a detailed comparison, the results were expressed as basic quantities in SI units: the depth in m or nm and the concentration in mole mole -1. The depth profiles were shown to differ significantly. Characteristic parameters, e.g. the maximum, the respective depth, the width and the dose or area of the profiles differ by a factor up to 3, the offset of the profiles (surface value at depth zero) even differs by more than one order of magnitude. The reason for such discrepancies were mainly found in an unsuitable calibration leading to high systematic errors. However, RBS and the new variant of TXRF showed reasonable, consistent profiles and a good correspondence which could be verified statistically after an estimation of their uncertainties.

  18. Enhanced model for determining the number of graphene layers and their distribution from X-ray diffraction data

    PubMed Central

    Ademi, Abdulakim; Grozdanov, Anita; Paunović, Perica; Dimitrov, Aleksandar T

    2015-01-01

    Summary A model consisting of an equation that includes graphene thickness distribution is used to calculate theoretical 002 X-ray diffraction (XRD) peak intensities. An analysis was performed upon graphene samples produced by two different electrochemical procedures: electrolysis in aqueous electrolyte and electrolysis in molten salts, both using a nonstationary current regime. Herein, the model is enhanced by a partitioning of the corresponding 2θ interval, resulting in significantly improved accuracy of the results. The model curves obtained exhibit excellent fitting to the XRD intensities curves of the studied graphene samples. The employed equation parameters make it possible to calculate the j-layer graphene region coverage of the graphene samples, and hence the number of graphene layers. The results of the thorough analysis are in agreement with the calculated number of graphene layers from Raman spectra C-peak position values and indicate that the graphene samples studied are few-layered. PMID:26665083

  19. Adaptive step-size algorithm for Fourier beam-propagation method with absorbing boundary layer of auto-determined width

    DOE PAGESBeta

    Learn, R.; Feigenbaum, E.

    2016-05-27

    Two algorithms that enhance the utility of the absorbing boundary layer are presented, mainly in the framework of the Fourier beam-propagation method. One is an automated boundary layer width selector that chooses a near-optimal boundary size based on the initial beam shape. Furthermore, the second algorithm adjusts the propagation step sizes based on the beam shape at the beginning of each step in order to reduce aliasing artifacts.

  20. Stratum corneum lipid matrix: Location of acyl ceramide and cholesterol in the unit cell of the long periodicity phase.

    PubMed

    Mojumdar, E H; Gooris, G S; Groen, D; Barlow, D J; Lawrence, M J; Demé, B; Bouwstra, J A

    2016-08-01

    The extracellular lipid matrix in the skin's outermost layer, the stratum corneum, is crucial for the skin barrier. The matrix is composed of ceramides (CERs), cholesterol (CHOL) and free fatty acids (FFAs) and involves two lamellar phases: the short periodicity phase (SPP) and the long periodicity phase (LPP). To understand the skin barrier thoroughly, information about the molecular arrangement in the unit cell of these lamellar phases is paramount. Previously we examined the molecular arrangement in the unit cell of the SPP. Furthermore X-ray and neutron diffraction revealed a trilayer arrangement of lipids within the unit cell of the LPP [D. Groen et al., Biophysical Journal, 97, 2242-2249, 2009]. In the present study, we used neutron diffraction to obtain more details about the location of lipid (sub)classes in the unit cell of the LPP. The diffraction pattern revealed at least 8 diffraction orders of the LPP with a repeating unit of 129.6±0.5Å. To determine the location of lipid sub(classes) in the unit cell, samples were examined with either only protiated lipids or selectively deuterated lipids. The diffraction data obtained by means of D2O/H2O contrast variation together with a gradual replacement of one particular CER, the acyl CER, by its partly deuterated counterpart, were used to construct the scattering length density profiles. The acyl chain of the acyl CER subclass is located at a position of ~21.4±0.2Å from the unit cell centre of the LPP. The position and orientation of CHOL in the LPP unit cell were determined using tail and head-group deuterated forms of the sterol. CHOL is located with its head-group positioned ~26±0.2Å from the unit cell centre. This allows the formation of a hydrogen bond with the ester group of the acyl CER located in close proximity. Based on the positions of the deuterated moieties of the acyl CER, CHOL and the previously determined location of two other lipid subclasses [E.H. Mojumdar et al., Biophysical Journal

  1. Adsorption of Human Tear Lipocalin to Human Meibomian Lipid Films

    PubMed Central

    Millar, Thomas J.; Mudgil, Poonam; Butovich, Igor A.; Palaniappan, Chendur K.

    2009-01-01

    Purpose Tear lipocalin (Tlc) is a major lipid binding protein in tears and is thought to have an important role in stabilizing the Meibomian lipid layer by transferring lipids to it from the aqueous layer or ocular surface, or by adsorbing to it directly. These possible roles have been investigated in vitro using human Tlc. Methods Tlc was purified from human tears by size exclusion chromatography followed by ion exchange chromatography. Three additional samples of the Tlc were prepared by lipidation, delipidation, and relipidation. The lipids extracted from the purified Tlc were analyzed by HPLC-MS followed by fragmentation. Adsorption of these different forms of Tlc to a human Meibomian lipid film spread on the surface of an artificial tear buffer in a Langmuir trough were observed by recording changes in the pressure with time (∏-T profile) and monitoring the appearance of the film microscopically. These results were compared with similar experiments using a bovine Meibomian lipid film. Results The results indicated that Tlc binds slowly to a human Meibomian lipid film compared with lysozyme or lactoferrin, even at 37°C. The adsorption of Tlc to a human Meibomian lipid film was very different from its adsorption to a bovine Meibomian lipid film, indicating the nature of the lipids in the film is critical to the adsorption process. Similarly, the different forms of Tlc had quite distinct adsorption patterns, as indicated both by changes in ∏-T profiles and the microscopic appearance of the films. Conclusions It was concluded that human Tlc was capable of adsorbing to and penetrating into a Meibomian lipid layer, but this process is very complex and depends on both the types of lipids bound to Tlc and the lipid complement comprising the Meibomian lipid film. PMID:18757516

  2. Lipid antigens in immunity

    PubMed Central

    Dowds, C. Marie; Kornell, Sabin-Christin

    2014-01-01

    Lipids are not only a central part of human metabolism but also play diverse and critical roles in the immune system. As such, they can act as ligands of lipid-activated nuclear receptors, control inflammatory signaling through bioactive lipids such as prostaglandins, leukotrienes, lipoxins, resolvins, and protectins, and modulate immunity as intracellular phospholipid- or sphingolipid-derived signaling mediators. In addition, lipids can serve as antigens and regulate immunity through the activation of lipid-reactive T cells, which is the topic of this review. We will provide an overview of the mechanisms of lipid antigen presentation, the biology of lipid-reactive T cells, and their contribution to immunity. PMID:23999493

  3. Determination of stoichiometry and concentration of trace elements in thin BaxSr1-xTiO3 perovskite layers.

    PubMed

    Becker, J S; Boulyga, S F

    2001-07-01

    This paper describes an analytical procedure for determining the stoichiometry of BaxSr1-xTiO3 perovskite layers using inductively coupled plasma mass spectrometry (ICP-MS). The analytical results of mass spectrometry measurements are compared to those of X-ray fluorescence analysis (XRF). The performance and the limits of solid-state mass spectrometry analytical methods for the surface analysis of thin BaxSr1-xTiO3 perovskite layers sputtered neutral mass spectrometry (SNMS)--are investigated and discussed. PMID:11496982

  4. An acpXL Mutant of Rhizobium leguminosarum bv. phaseoli Lacks 27-Hydroxyoctacosanoic Acid in Its Lipid A and Is Developmentally Delayed during Symbiotic Infection of the Determinate Nodulating Host Plant Phaseolus vulgaris ▿

    PubMed Central

    Brown, Dusty B.; Huang, Yu-Chu; Kannenberg, Elmar L.; Sherrier, D. Janine; Carlson, Russell W.

    2011-01-01

    Rhizobium leguminosarum is a Gram-negative bacterium that forms nitrogen-fixing symbioses with compatible leguminous plants via intracellular invasion and establishes a persistent infection within host membrane-derived subcellular compartments. Notably, an unusual very-long-chain fatty acid (VLCFA) is found in the lipid A of R. leguminosarum as well as in the lipid A of the medically relevant pathogens Brucella abortus, Brucella melitensis, Bartonella henselae, and Legionella pneumophila, which are also able to persist within intracellular host-derived membranes. These bacterial symbionts and pathogens each contain a homologous gene region necessary for the synthesis and transfer of the VLCFA to the lipid A. Within this region lies a gene that encodes the specialized acyl carrier protein AcpXL, on which the VLCFA is built. This study describes the biochemical and infection phenotypes of an acpXL mutant which lacks the VLCFA. The mutation was created in R. leguminosarum bv. phaseoli strain 8002, which forms symbiosis with Phaseolus vulgaris, a determinate nodulating legume. Structural analysis using gas chromatography and mass spectrometry revealed that the mutant lipid A lacked the VLCFA. Compared to the parent strain, the mutant was more sensitive to the detergents deoxycholate and dodecyl sulfate and the antimicrobial peptide polymyxin B, suggesting a compromise to membrane stability. In addition, the mutant was more sensitive to higher salt concentrations. Passage through the plant restored salt tolerance. Electron microscopic examination showed that the mutant was developmentally delayed during symbiotic infection of the host plant Phaseolus vulgaris and produced abnormal symbiosome structures. PMID:21764936

  5. Lipid14: The Amber Lipid Force Field.

    PubMed

    Dickson, Callum J; Madej, Benjamin D; Skjevik, Age A; Betz, Robin M; Teigen, Knut; Gould, Ian R; Walker, Ross C

    2014-02-11

    The AMBER lipid force field has been updated to create Lipid14, allowing tensionless simulation of a number of lipid types with the AMBER MD package. The modular nature of this force field allows numerous combinations of head and tail groups to create different lipid types, enabling the easy insertion of new lipid species. The Lennard-Jones and torsion parameters of both the head and tail groups have been revised and updated partial charges calculated. The force field has been validated by simulating bilayers of six different lipid types for a total of 0.5 μs each without applying a surface tension; with favorable comparison to experiment for properties such as area per lipid, volume per lipid, bilayer thickness, NMR order parameters, scattering data, and lipid lateral diffusion. As the derivation of this force field is consistent with the AMBER development philosophy, Lipid14 is compatible with the AMBER protein, nucleic acid, carbohydrate, and small molecule force fields. PMID:24803855

  6. Determination of the emission zone in a single-layer polymer light-emitting diode through optical measurements

    SciTech Connect

    Granlund, Thomas; Pettersson, Leif A. A.; Inganas, Olle

    2001-06-01

    We study the emission zone in a single-layer polymer light-emitting diode. The emission zone is found by studying the angular distribution of the electroluminescence. The emission is modeled by accounting for optical interference. We account for birefringence of the anode layer in our model. The active polymer was, however, found to be isotropic. The anode consists of a single-layer of the conducting polymer complex poly(3,4-ethylenedioxythiophene) and poly(styrene sulfonate) (PEDOT-PSS), with enhanced conductivity. As a cathode we use plain aluminum. By using only PEDOT-PSS we avoid having a thin metal layer or indium-tin-oxide as the anode in the path of the escaping light. The active material is a substituted polythiophene with excellent film forming properties. A comparison between the experimental and calculated angular distribution of light emission from a single-layered polymer light-emitting diode was shown to be in good agreement for the spectral region studied. By assuming a distribution of the emission zone, we deduce the position as well as the width of the zone. {copyright} 2001 American Institute of Physics.

  7. Tocopheryl acetate nanoemulsions stabilized with lipid-polymer hybrid emulsifiers for effective skin delivery.

    PubMed

    Nam, Yoon Sung; Kim, Jin-Woong; Park, Jaeyoon; Shim, Jongwon; Lee, Jong Suk; Han, Sang Hoon

    2012-06-01

    Tocopheryl acetate is used as the oil component of nanoemulsions using a mixture of unsaturated phospholipids and polyethylene oxide-block-poly(ε-caprolactone) (PEO-b-PCL). This study investigates the effects of the lipid-polymer composition on the size and surface charge of nanoemulsions, microviscosity of the interfacial layer, and skin absorption of tocopheryl acetate. The lipid-polymer hybrid system exhibits excellent colloidal dispersion stability, which is comparable to that of polymer-based nanoemulsions. If lipids are used as emulsifiers, nanoemulsions show poor dispersion stability despite a good skin absorption enhancing effect. The amount of tocopheryl acetate absorbed by the skin increases with an increased lipid-to-polymer ratio, as determined using the hairless guinea pig skin loaded in a Franz-type diffusion cell. An 8:2 (w/w) mixture of unsaturated phospholipids and PEO-b-PCL exhibits the most efficient delivery of tocopheryl acetate into the skin. Our results show that tocopheryl acetate is absorbed almost twice as fast by the lipid-polymer hybrid system than the nanoemulsions stabilized with PEO-b-PCL. This study suggests that the lipid-polymer hybrid system can be used as an effective means of optimizing nanoemulsions in terms of dispersion stability and skin delivery capability. PMID:22326341

  8. High performance liquid chromatography: Tandem mass spectrometric determination of cisplatin levels in different visceral pleura layers of rats

    PubMed Central

    XIA, HUI; ZHANG, WEN; LI, YINGJIE; YU, CHANGHAI

    2015-01-01

    The aim of the present study was to investigate the concentration of cisplatin in different layers of the visceral pleura in rats, following drug administration. In this study, a sensitive and specific liquid chromatography method coupled with electrospray ionization-tandem mass spectrometry was established to investigate the disposition of cisplatin in different layers of the visceral pleura in rats. Methodological data, including specificity, linearity, accuracy, recovery, precision and lower limits of quantification, confirmed that this novel method may be used to efficiently quantify the cisplatin concentrations in visceral pleura of rats following administration of the drug. Furthermore, the results demonstrated that the desired drug concentration was not achieved in the outer or inner elastic layers of the visceral pleura following injection with cisplatin through various administration methods. PMID:26137076

  9. Determination of Boundary-Layer Transition on Three Symmetrical Airfoils in the NACA Full-Scale Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Silverstein, Abe; Becker, John V

    1938-01-01

    For the purpose of studying the transition from laminar to turbulent flow, boundary-layer measurements were made in the NACA full-scale wind tunnel on three symmetrical airfoils of NACA 0009, 0012, and 0018 sections. The effects of variations in lift coefficient, Reynolds number, and airfoil thickness on transition were investigated. Air speed in the boundary layer was measured by total-head tubes and by hot wires; a comparison of transition as indicated by the two techniques was obtained. The results indicate no unique value of Reynolds number for the transition, whether the Reynolds number is based upon the distance along the chord or upon the thickness of the boundary layer at the transition point. In general, the transition is not abrupt and occurs in a region that varies in length as a function of the test conditions.

  10. Tear lipocalin captures exogenous lipid from abnormal corneal surfaces.

    PubMed

    Glasgow, Ben J; Gasymov, Oktay K; Abduragimov, Adil R; Engle, Jamison J; Casey, Richard C

    2010-04-01

    Purpose. The cornea is protected by apical hydrophilic transmembrane mucins and tears. In pathologic states the mucin barrier is disrupted, creating potential for meibomian lipids to adhere more strongly. Undisplaced lipids create an unwettable surface. The hypothesis that pathologic ocular surfaces alter lipid binding and the ability of tear proteins to remove lipids was tested. Methods. Corneas with pathologic surfaces were studied for lipid adhesion and removal by tears. Capture of fluorescence-labeled phospholipids by human tears was assessed by steady state fluorometry. Tear proteins were separated by gel filtration chromatography and analyzed for bound lipids. Results. Contact angle measurements revealed strong lipid adherence to corneas submerged in buffer. Lower contact angles are observed for lipids on completely de-epithelialized corneas compared with intact corneas (P = 0.04). Lipid removal from these surfaces is greater with whole tears than with tears depleted of tear lipocalin (P < 0.0005). Significantly fewer lipids are captured by tears from Bowman's layer than from epithelial-bearing surfaces (P < 0.025). The only tear component to bind the fluorescence-tagged lipid is tear lipocalin. The histology of a rare case of dry eye disease demonstrates the dominant features of contemporaneous bullous keratopathy. Lipid sequestration from this cornea by tear lipocalin was robust. Conclusions. Lipid is captured by tear lipocalin from corneas with bullous keratopathy and dry eye. Lipid removal is slightly abrogated by greater lipid adhesion to Bowman's layer. Reduced secretion of tear lipocalin documented in dry eye disease could hamper lipid removal and exacerbate ocular surface pathology. PMID:19959641

  11. Tear Lipocalin Captures Exogenous Lipid from Abnormal Corneal Surfaces

    PubMed Central

    Gasymov, Oktay K.; Abduragimov, Adil R.; Engle, Jamison J.; Casey, Richard C.

    2010-01-01

    Purpose. The cornea is protected by apical hydrophilic transmembrane mucins and tears. In pathologic states the mucin barrier is disrupted, creating potential for meibomian lipids to adhere more strongly. Undisplaced lipids create an unwettable surface. The hypothesis that pathologic ocular surfaces alter lipid binding and the ability of tear proteins to remove lipids was tested. Methods. Corneas with pathologic surfaces were studied for lipid adhesion and removal by tears. Capture of fluorescence-labeled phospholipids by human tears was assessed by steady state fluorometry. Tear proteins were separated by gel filtration chromatography and analyzed for bound lipids. Results. Contact angle measurements revealed strong lipid adherence to corneas submerged in buffer. Lower contact angles are observed for lipids on completely de-epithelialized corneas compared with intact corneas (P = 0.04). Lipid removal from these surfaces is greater with whole tears than with tears depleted of tear lipocalin (P < 0.0005). Significantly fewer lipids are captured by tears from Bowman's layer than from epithelial-bearing surfaces (P < 0.025). The only tear component to bind the fluorescence-tagged lipid is tear lipocalin. The histology of a rare case of dry eye disease demonstrates the dominant features of contemporaneous bullous keratopathy. Lipid sequestration from this cornea by tear lipocalin was robust. Conclusions. Lipid is captured by tear lipocalin from corneas with bullous keratopathy and dry eye. Lipid removal is slightly abrogated by greater lipid adhesion to Bowman's layer. Reduced secretion of tear lipocalin documented in dry eye disease could hamper lipid removal and exacerbate ocular surface pathology. PMID:19959641

  12. Structure determination of functional membrane proteins using small-angle neutron scattering (sans) with small, mixed-lipid liposomes: native beef heart mitochondrial cytochrome c oxidase forms dimers.

    PubMed

    Rubinson, Kenneth A; Pokalsky, Christine; Krueger, Susan; Prochaska, Lawrence J

    2013-01-01

    The low-resolution three-dimensional structure of purified native beef heart mitochondrial cytochrome c oxidase (COX) in asolectin unilamellar liposomes has been measured by small-angle neutron scattering under the conditions where the protein remains fully functional. From a neutron scattering perspective, the use of mixed-lipid liposomes provided for a more homogeneous matrix than can be achieved using a single lipid. As a result, the measurements were able to be performed under conditions where the liposome scattering was essentially eliminated (contrast-matched conditions). The protein structure in the membrane was modeled as a simple parallelepiped with side lengths of (59 × 70 × 120) Å with uncertainties, respectively, (11, 12, 20 Å). The molecular mass calculated for a typical protein with this volume is estimated to be (410 ± 124) kDa, which indicates the mass of a COX dimer. The longest dimension has some uncertainty due to intermolecular scattering contributing to the data. Nevertheless, that length was estimated using an average protein density and the known dimer molecular mass. Using the same cross sectional dimensions for the structure, the length is estimated to be 120 Å. However, the measured scattering curve of the dimer in the liposome differs significantly from that calculated from the X-ray structure of the dimer in a crystal of mixed micelles (PDB 3AG1). The calculated SANS scattering from the crystal structure was fit with a parallelepiped, measuring (59 × 101 × 129) Å with fitting uncertainties, respectively, (2, 3, 3 Å). Our results suggest that COX is a functional dimer when reconstituted into mixed-lipid liposomes. PMID:23143018

  13. Determination of membrane cholesterol partition coefficient using a lipid vesicle-cyclodextrin binary system: effect of phospholipid acyl chain unsaturation and headgroup composition.

    PubMed Central

    Niu, Shui-Lin; Litman, Burton J

    2002-01-01

    Lateral domain or raft formation in biological membranes is often discussed in terms of cholesterol-lipid interactions. Preferential interactions of cholesterol with lipids, varying in headgroup and acyl chain unsaturation, were studied by measuring the partition coefficient for cholesterol in unilamellar vesicles. A novel vesicle-cyclodextrin system was used, which precludes the possibility of cross-contamination between donor-acceptor vesicles or the need to modify one of the vesicle populations. Variation in phospholipid headgroup resulted in cholesterol partitioning in the order of sphingomyelin (SM) > phosphatidylserine > phosphatidylcholine (PC) > phosphatidylenthanolamine (PE), spanning a range of partition DeltaG of -1181 cal/mol to +683 cal/mol for SM and PE, respectively. Among the acyl chains examined, the order of cholesterol partitioning was 18:0(stearic acid),18:1n-9(oleic acid) PC > di18:1n-9PC > di18:1n-12(petroselenic acid) PC > di18:2n-6(linoleic acid) PC > 16:0(palmitic acid),22:6n-3(DHA) PC > di18:3n-3(alpha-linolenic acid) PC > di22:6n-3PC with a range in partition DeltaG of 913 cal/mol. Our results suggest that the large differences observed in cholesterol-lipid interactions contribute to the forces responsible for lateral domain formation in plasma membranes. These differences may also be responsible for the heterogeneous cholesterol distribution in cellular membranes, where cholesterol is highly enriched in plasma membranes and relatively depleted in intracellular membranes. PMID:12496107

  14. The Structural Quality of AlxGa1-xN Epitaxial Layers Grown by Digitally-AlloyedModulated Precursor Epitaxy Determined by Transmission Electron Microscopy

    SciTech Connect

    Hawkridge, Michael E; Liliental-Weber, Zuzanna; Kim, Hee Jin; Choi, Suk; Yoo, Dongwon; Ryou, Jae-Hyun; Dupuis, Russell

    2008-10-13

    Al(x)Ga(1-x)N layers of varying composition (0.5layers by metalorganic chemical vapor deposition on AlN templates were characterized by transmission electron microscopy techniques. Fine lamellae were observed in bright field images that indicate a possible variation in composition due to the modulated nature of growth. In higher Ga content samples (x(Al)<0.75), a compositional inhomogeniety associated with thicker island regions was observed, which is determined to be due to large Ga-rich areas formed at the base of the layer. Possible causes for the separation of Ga-rich material are discussed in the context of the growth regime used.

  15. Absorption properties of micellar lipid metabolites into Caco2 cells.

    PubMed

    Tsuzuki, Wakako

    2007-07-01

    To elucidate the absorption characteristics of dietary lipids in the human intestine, we investigated the cellular uptake of lipid metabolites using a differential monolayer of the Caco2 cells. As lipid metabolites, several free fatty acids and 2-monoacylglycerols, were formed a mixed micelle by bile salts and lysophospholipids and they were supplied to the Caco2 cells. To estimate the effect of the mixed micelles on the permeability of cells' membranes during incubation with the mixed micelles, the transepitherial electrical resistance (TEER) value was monitored, and no pronounced changes of TEER was detected. This suggested that mixed micelles did not affect their cellular properties of the barrier measured by TEER. The lipid metabolites transferred from the mixed micelle into the Caco2 cells were determined quantitatively by an enzymatic colorimetric method and were done by thin layer chromatography (TLC) for a species of acylglycerols. These highly sensitive methods enabled us to monitor the transepithelial transports of various kinds of non-isotope-labeled various lipid metabolites. Newly re-synthesized triacylglycerols were accumulated in Caco2 cells after 30 min incubation with the mixed micelles, and their amounts increased gradually for 4 h. The secretion of re-esterified triacylglycerols into a basolateral medium from the Caco2 cells began at 2 h after the mixed micelles were added to the apical medium. The intake of external lipid metabolites by the Caco2 cells were evaluated by an initial 2-h incubation with the mixed micelles. For example, 2-monomyristin and 2-monopalmitin were more rapidly transferred into the Caco2 cells from the mixed micelles than 2-monocaprin was. On the other hand, the absorption rates of capric acid, lauric acid and myristic acid by the cells were larger than those of stearic acid and oleic acid. It revealed that the side-chain structure of these lipid metabolites affected their absorption by the Caco2 cells. The results of this

  16. A Laboratory Experiment in Pharmaceutical Analysis: Determination of Drugs of Abuse in Human Urine by Thin-Layer Chromatography.

    ERIC Educational Resources Information Center

    Bailey, Leonard C.

    1979-01-01

    An experiment is described that was developed for a course in Inorganic and Analytical Pharmaceutical Chemistry at Rutgers University to provide pharmacy students with practical experience in the thin-layer chromatography used for the analysis of urine to monitor patient compliance with drug abuse treatment programs. (JMD)

  17. Composition determination of quaternary GaAsPN layers from single X-ray diffraction measurement of quasi-forbidden (002) reflection

    SciTech Connect

    Tilli, J.-M. Jussila, H.; Huhtio, T.; Sopanen, M.; Yu, K. M.

    2014-05-28

    GaAsPN layers with a thickness of 30 nm were grown on GaP substrates with metalorganic vapor phase epitaxy to study the feasibility of a single X-ray diffraction (XRD) measurement for full composition determination of quaternary layer material. The method is based on the peak intensity of a quasi-forbidden (002) reflection, which is shown to vary with changing arsenic content for GaAsPN. The method works for thin films with a wide range of arsenic contents and shows a clear variation in the reflection intensity as a function of changing layer composition. The obtained thicknesses and compositions of the grown layers are compared with accurate reference values obtained by Rutherford backscattering spectroscopy combined with nuclear reaction analysis measurements. Based on the comparison, the error in the XRD defined material composition becomes larger with increasing nitrogen content and layer thickness. This suggests that the dominating error source is the deteriorated crystal quality due to the nonsubstitutional incorporation of nitrogen into the crystal lattice and strain relaxation. The results reveal that the method overestimates the arsenic and nitrogen content within error margins of about 0.12 and about 0.025, respectively.

  18. Effect of cell rupturing methods on the drying characteristics and lipid compositions of microalgae.

    PubMed

    Viswanathan, T; Mani, S; Das, K C; Chinnasamy, S; Bhatnagar, A; Singh, R K; Singh, M

    2012-12-01

    This paper investigated the effect of cell rupturing methods on the drying characteristics and the lipid compositions of a green algae consortium grown in an open raceway pond. The ruptured microalgae samples obtained from French press, autoclave and sonication methods were used for conducting thin layer drying experiment at four drying temperatures (30, 50, 70 and 90 °C). The rate of moisture removal at each drying condition was recorded until no change in moisture loss. A typical drying curve for a microalgae consortium indicated that the rate of drying was limited by diffusion. Among three drying models (Newton, Page and Henderson-Pabis) used to fit the drying data, Page model fitted well on the experimental drying data with a coefficient of determination (R(2)) of 0.99. Solvent extraction of French press ruptured cells produced the highest total lipid yield with no significant change in lipid compositions. PMID:23073099

  19. The Flip-Flop Diffusion Mechanism across Lipids in a Hybrid Bilayer Membrane.

    PubMed

    Barile, Christopher J; Tse, Edmund C M; Li, Ying; Gewargis, John P; Kirchschlager, Nicholas A; Zimmerman, Steven C; Gewirth, Andrew A

    2016-06-01

    In this study, we examine the mechanism of flip-flop diffusion of proton carriers across the lipid layer of a hybrid bilayer membrane (HBM). The HBM consists of a lipid monolayer appended on top of a self-assembled monolayer containing a Cu-based O2 reduction catalyst on a Au electrode. The flip-flop diffusion rates of the proton carriers dictate the kinetics of O2 reduction by the electrocatalyst. By varying both the tail lengths of the proton carriers and the lipids, we find the combinations of lengths that maximize the flip-flop diffusion rate. These experimental results combined with biophysical modeling studies allow us to propose a detailed mechanism for transmembrane flip-flop diffusion in HBM systems, which involves the bending of the alkyl tail of the proton carrier as the rate-determining step. Additional studies with an unbendable proton carrier further validate these mechanistic findings. PMID:27276263

  20. A robust post-processing method to determine skin friction in turbulent boundary layers from the velocity profile

    NASA Astrophysics Data System (ADS)

    Rodríguez-López, Eduardo; Bruce, Paul J. K.; Buxton, Oliver R. H.

    2015-04-01

    The present paper describes a method to extrapolate the mean wall shear stress, , and the accurate relative position of a velocity probe with respect to the wall, , from an experimentally measured mean velocity profile in a turbulent boundary layer. Validation is made between experimental and direct numerical simulation data of turbulent boundary layer flows with independent measurement of the shear stress. The set of parameters which minimize the residual error with respect to the canonical description of the boundary layer profile is taken as the solution. Several methods are compared, testing different descriptions of the canonical mean velocity profile (with and without overshoot over the logarithmic law) and different definitions of the residual function of the optimization. The von Kármán constant is used as a parameter of the fitting process in order to avoid any hypothesis regarding its value that may be affected by different initial or boundary conditions of the flow. Results show that the best method provides an accuracy of for the estimation of the friction velocity and for the position of the wall. The robustness of the method is tested including unconverged near-wall measurements, pressure gradient, and reduced number of points; the importance of the location of the first point is also tested, and it is shown that the method presents a high robustness even in highly distorted flows, keeping the aforementioned accuracies if one acquires at least one data point in . The wake component and the thickness of the boundary layer are also simultaneously extrapolated from the mean velocity profile. This results in the first study, to the knowledge of the authors, where a five-parameter fitting is carried out without any assumption on the von Kármán constant and the limits of the logarithmic layer further from its existence.

  1. Combined optical and acoustical method for determination of thickness and porosity of transparent organic layers below the ultra-thin film limit

    NASA Astrophysics Data System (ADS)

    Rodenhausen, K. B.; Kasputis, T.; Pannier, A. K.; Gerasimov, J. Y.; Lai, R. Y.; Solinsky, M.; Tiwald, T. E.; Wang, H.; Sarkar, A.; Hofmann, T.; Ianno, N.; Schubert, M.

    2011-10-01

    Analysis techniques are needed to determine the quantity and structure of materials composing an organic layer that is below an ultra-thin film limit and in a liquid environment. Neither optical nor acoustical techniques can independently distinguish between thickness and porosity of ultra-thin films due to parameter correlation. A combined optical and acoustical approach yields sufficient information to determine both thickness and porosity. We describe application of the combinatorial approach to measure single or multiple organic layers when the total layer thickness is small compared to the wavelength of the probing light. The instrumental setup allows for simultaneous in situ spectroscopic ellipsometry and quartz crystal microbalance dynamic measurements, and it is combined with a multiple-inlet fluid control system for different liquid solutions to be introduced during experiments. A virtual separation approach is implemented into our analysis scheme, differentiated by whether or not the organic adsorbate and liquid ambient densities are equal. The analysis scheme requires that the film be assumed transparent and rigid (non-viscoelastic). We present and discuss applications of our approach to studies of organic surfactant adsorption, self-assembled monolayer chemisorption, and multiple-layer target DNA sensor preparation and performance testing.

  2. Combined optical and acoustical method for determination of thickness and porosity of transparent organic layers below the ultra-thin film limit.

    PubMed

    Rodenhausen, K B; Kasputis, T; Pannier, A K; Gerasimov, J Y; Lai, R Y; Solinsky, M; Tiwald, T E; Wang, H; Sarkar, A; Hofmann, T; Ianno, N; Schubert, M

    2011-10-01

    Analysis techniques are needed to determine the quantity and structure of materials composing an organic layer that is below an ultra-thin film limit and in a liquid environment. Neither optical nor acoustical techniques can independently distinguish between thickness and porosity of ultra-thin films due to parameter correlation. A combined optical and acoustical approach yields sufficient information to determine both thickness and porosity. We describe application of the combinatorial approach to measure single or multiple organic layers when the total layer thickness is small compared to the wavelength of the probing light. The instrumental setup allows for simultaneous in situ spectroscopic ellipsometry and quartz crystal microbalance dynamic measurements, and it is combined with a multiple-inlet fluid control system for different liquid solutions to be introduced during experiments. A virtual separation approach is implemented into our analysis scheme, differentiated by whether or not the organic adsorbate and liquid ambient densities are equal. The analysis scheme requires that the film be assumed transparent and rigid (non-viscoelastic). We present and discuss applications of our approach to studies of organic surfactant adsorption, self-assembled monolayer chemisorption, and multiple-layer target DNA sensor preparation and performance testing. PMID:22047284

  3. Stacking sequence determines Raman intensities of observed interlayer shear modes in 2D layered materials – A general bond polarizability model

    PubMed Central

    Luo, Xin; Lu, Xin; Cong, Chunxiao; Yu, Ting; Xiong, Qihua; Ying Quek, Su

    2015-01-01

    2D layered materials have recently attracted tremendous interest due to their fascinating properties and potential applications. The interlayer interactions are much weaker than the intralayer bonds, allowing the as-synthesized materials to exhibit different stacking sequences, leading to different physical properties. Here, we show that regardless of the space group of the 2D materials, the Raman frequencies of the interlayer shear modes observed under the typical configuration blue shift for AB stacked materials, and red shift for ABC stacked materials, as the number of layers increases. Our predictions are made using an intuitive bond polarizability model which shows that stacking sequence plays a key role in determining which interlayer shear modes lead to the largest change in polarizability (Raman intensity); the modes with the largest Raman intensity determining the frequency trends. We present direct evidence for these conclusions by studying the Raman modes in few layer graphene, MoS2, MoSe2, WSe2 and Bi2Se3, using both first principles calculations and Raman spectroscopy. This study sheds light on the influence of stacking sequence on the Raman intensities of intrinsic interlayer modes in 2D layered materials in general, and leads to a practical way of identifying the stacking sequence in these materials. PMID:26469313

  4. Stacking sequence determines Raman intensities of observed interlayer shear modes in 2D layered materials--A general bond polarizability model.

    PubMed

    Luo, Xin; Lu, Xin; Cong, Chunxiao; Yu, Ting; Xiong, Qihua; Quek, Su Ying

    2015-01-01

    2D layered materials have recently attracted tremendous interest due to their fascinating properties and potential applications. The interlayer interactions are much weaker than the intralayer bonds, allowing the as-synthesized materials to exhibit different stacking sequences, leading to different physical properties. Here, we show that regardless of the space group of the 2D materials, the Raman frequencies of the interlayer shear modes observed under the typical z(xx)z configuration blue shift for AB stacked materials, and red shift for ABC stacked materials, as the number of layers increases. Our predictions are made using an intuitive bond polarizability model which shows that stacking sequence plays a key role in determining which interlayer shear modes lead to the largest change in polarizability (Raman intensity); the modes with the largest Raman intensity determining the frequency trends. We present direct evidence for these conclusions by studying the Raman modes in few layer graphene, MoS2, MoSe2, WSe2 and Bi2Se3, using both first principles calculations and Raman spectroscopy. This study sheds light on the influence of stacking sequence on the Raman intensities of intrinsic interlayer modes in 2D layered materials in general, and leads to a practical way of identifying the stacking sequence in these materials. PMID:26469313

  5. The cellular lipids of Romboutsia.

    PubMed

    Guan, Ziqiang; Chen, Lingli; Gerritsen, Jacoline; Smidt, Hauke; Goldfine, Howard

    2016-09-01

    We have examined the lipids of three isolates, Romboutsia lituseburensis, Romboutsia ilealis, and Romboutsia sp. strain FRIFI, of the newly described genus Romboutsia by two-dimensional thin-layer chromatography (2D-TLC) and by liquid chromatography/mass spectrometry (LC/MS). We have found three phospholipids, phosphatidylglycerol (PG), cardiolipin and phosphatidic acid in all three species. A fourth phospholipid, lysyl-PG, was found in R. lituseburensis and strain FRIFI. Polyprenyl-phosphates were identified in the lipid extracts of all three species. Three glycolipids, mono-, di- and tri-hexosyldiacylglycerol, were common to all three species. An additional glycolipid, tetrahexosyl-diacylglycerol was identified in strain FRIFI. Acylated trihexosyldiacylglycerol and acyl-tetrahexosydiacylglycerol were also found in R. ilealis and strain FRIFI. Remarkably, no alk-1-enyl ether lipids (plasmalogens) were present in Romboutsia as distinct from bacteria of the related genus Clostridium in which these ether lipids are common. We have compared the lipidome of Romboutsia with that recently described for Clostridium difficile, which has plasmalogens, no lysyl-PG, and no tetrahexosyl-diacylglycerol. According to 16S rRNA gene sequencing, Romboutsia spp. and C. difficile are closely related (>95% sequence identity). PMID:27317428

  6. Local environment and composition of magnesium gallium layered double hydroxides determined from solid-state 1H and 71Ga NMR spectroscopy

    SciTech Connect

    Petersen, Line B.; Lipton, Andrew S.; Zorin, Vadim; Nielsen, Ulla Gro

    2014-11-01

    Ordering of gallium(III) in a series of magnesium gallium layered double hydroxides (LDH’s), [Mg1-xGax(OH)2(NO3)x yH2O], was determined using solid-state 1H and 71Ga NMR spectroscopy. Depletion of Ga in these LDH’s is demonstrated to be the result of soluble [Ga(OH)4]-complexes formed during synthesis.

  7. Synthesis, characterization and structure determination of two isotypes of a layered aluminophosphate with a new 2D network topology

    SciTech Connect

    Tuel, A. . E-mail: tuel@catalyse.cnrs.fr; Lorentz, Ch.; Gramlich, V.; Baerlocher, Ch.

    2005-07-15

    Two isotypes of a new layered aluminophosphate, further denoted MDAP-3 and MDAE-1, have been synthesized under hydrothermal conditions using N-methyl-1,3-propanediamine and N-methyl-ethylenediamine, respectively. MDAP-3, with the empirical formula [Al{sub 2}(HPO{sub 4})(PO{sub 4}){sub 2}](C{sub 4}N{sub 2}H{sub 14})(H{sub 2}O), crystallizes in the orthorhombic space group Pna2(1) (No. 33) with a=9.602(16)A, b=9.26(2)A, c=16.03(3)A, Z=4, R{sub 1}=0.0498 and wR{sub 2}=0.1217. The second solid, MDAE-1, with the empirical formula [Al{sub 2}(HPO{sub 4})(PO{sub 4}){sub 2}](C{sub 3}N{sub 2}H{sub 12})(H{sub 2}O), crystallizes in the same space group with a=9.4250(19)A, b=9.3170(19)A, c=15.907(3)A, Z=4, R{sub 1}=0.0407 and wR{sub 2}=0.0954. The two compounds possess the same layer topology. Inorganic layers contain PO{sub 3}=O, PO{sub 3}OH, AlO{sub 4} and AlO{sub 6} polyhedra, linked together to generate a new 4x8 net. MDAP-3 and MDAE-1 represent the first examples of two-dimensional layered aluminophosphates with the Al{sub 2}P{sub 3}O{sub 12} stoichiometry, and containing AlO{sub 6} octahedra.

  8. Doxorubicin Lipid Complex Injection

    MedlinePlus

    Doxorubicin lipid complex is used to treat ovarian cancer that has not improved or that has worsened after treatment with other medications. Doxorubicin lipid complex is also used to treat Kaposi's sarcoma ( ...

  9. Daunorubicin Lipid Complex Injection

    MedlinePlus

    Daunorubicin lipid complex is used to treat advanced Kaposi's sarcoma (a type of cancer that causes abnormal tissue to ... body) related to acquired immunodeficiency syndrome (AIDS). Daunorubicin lipid complex is in a class of medications called ...

  10. Vincristine Lipid Complex Injection

    MedlinePlus

    Vincristine lipid complex is used to treat a certain type of acute lymphoblastic leukemia (ALL; a type of cancer ... least two different treatments with other medications. Vincristine lipid complex is in a class of medications called ...

  11. Disorders of Lipid Metabolism

    MedlinePlus

    ... Metabolic Disorders Disorders of Carbohydrate Metabolism Disorders of Amino Acid Metabolism Disorders of Lipid Metabolism Fats (lipids) are ... carbohydrates and low in fats. Supplements of the amino acid carnitine may be helpful. The long-term outcome ...

  12. Daunorubicin Lipid Complex Injection

    MedlinePlus

    Daunorubicin lipid complex is used to treat advanced Kaposi's sarcoma (a type of cancer that causes abnormal tissue to grow on ... related to acquired immunodeficiency syndrome (AIDS). Daunorubicin lipid complex is in a class of medications called anthracyclines. ...

  13. Cytarabine Lipid Complex Injection

    MedlinePlus

    Cytarabine lipid complex is used to treat lymphomatous meningitis (a type of cancer in the covering of the spinal cord and brain). Cytarabine lipid complex is in a class of medications called antimetabolites. ...

  14. Irinotecan Lipid Complex Injection

    MedlinePlus

    Irinotecan lipid complex is used in combination with other medications to treat pancreatic cancer that has spread to other parts of ... after treatment with other chemotherapy medications. Irinotecan lipid complex is in a class of antineoplastic medications called ...

  15. Doxorubicin Lipid Complex Injection

    MedlinePlus

    Doxorubicin lipid complex is used to treat ovarian cancer that has not improved or that has worsened after treatment with other medications. Doxorubicin lipid complex is also used to treat Kaposi's sarcoma (a ...

  16. Vincristine Lipid Complex Injection

    MedlinePlus

    Vincristine lipid complex is used to treat a certain type of acute lymphoblastic leukemia (ALL; a type of cancer of the ... two different treatments with other medications. Vincristine lipid complex is in a class of medications called vinca ...

  17. Irinotecan Lipid Complex Injection

    MedlinePlus

    Irinotecan lipid complex is used in combination with other medications to treat pancreatic cancer that has spread ... has worsened after treatment with other chemotherapy medications. Irinotecan lipid complex is in a class of antineoplastic ...

  18. Lipid Exchange by Ultracentrifugation.

    PubMed

    Drachmann, Nikolaj Düring; Olesen, Claus

    2016-01-01

    Lipids play an important role in maintaining P-type ATPase structure and function, and often they are crucial for ATPase activity. When the P-type ATPases are in the membrane, they are surrounded by a mix of different lipid species with varying aliphatic chain lengths and saturation, and the complex interplay between the lipids and the P-type ATPases are still not well understood. We here describe a robust method to exchange the majority of the lipids surrounding the ATPase after solubilisation and/or purification with a target lipid of interest. The method is based on an ultracentrifugation step, where the protein sample is spun through a dense buffer containing large excess of the target lipid, which results in an approximately 80-85 % lipid exchange. The method is a very gently technique that maintains protein folding during the process, hence allowing further characterization of the protein in the presence of a target lipid of interest. PMID:26695050

  19. Nuclear lipid droplets: a novel nuclear domain.

    PubMed

    Layerenza, J P; González, P; García de Bravo, M M; Polo, M P; Sisti, M S; Ves-Losada, A

    2013-02-01

    We investigated nuclear neutral-lipid (NL) composition and organization, as NL may represent an alternative source for providing fatty acids and cholesterol (C) to membranes, signaling paths, and transcription factors in the nucleus. We show here that nuclear NL were organized into nonpolar domains in the form of nuclear-lipid droplets (nLD). By fluorescent confocal microscopy, representative nLD were observed in situ within the nuclei of rat hepatocytes in vivo and HepG2 cells, maintained under standard conditions in culture, and within nuclei isolated from rat liver. nLD were resistant to Triton X-100 and became stained with Sudan Red, OsO4, and BODIPY493/503. nLD and control cytosolic-lipid droplets (cLD) were isolated from rat-liver nuclei and from homogenates, respectively, by sucrose-gradient sedimentation. Lipids were extracted, separated by thin-layer chromatography, and quantified. nLD were composed of 37% lipids and 63% proteins. The nLD lipid composition was as follows: 19% triacylglycerols (TAG), 39% cholesteryl esters, 27% C, and 15% polar lipids; whereas the cLD composition contained different proportions of these same lipid classes, in particular 91% TAG. The TAG fatty acids from both lipid droplets were enriched in oleic, linoleic, and palmitic acids. The TAG from the nLD corresponded to a small pool, whereas the TAG from the cLD constituted the main cellular pool (at about 100% yield from the total homogenate). In conclusion, nLD are a domain within the nucleus where NL are stored and organized and may be involved in nuclear lipid homeostasis. PMID:23098923

  20. Skin lipids from Saudi Arabian birds.

    PubMed

    Khan, Haseeb A; Arif, Ibrahim A; Williams, Joseph B; Champagne, Alex M; Shobrak, Mohammad

    2014-04-01

    Skin lipids play an important role in the regulation of cutaneous water loss (CWL). Earlier studies have shown that Saudi desert birds exhibit a tendency of reduced CWL than birds from temperate environment due to adaptive changes in composition of their skin lipids. In this study, we used thin-layer chromatography (TLC) for separation and detection of non-polar and polar lipids from the skin of six bird species including sooty gull, brown booby, house sparrow, Arabian waxbill, sand partridge, and laughing dove. The lipids were separated and detected on Silica gel G coated TLC plates and quantified by using densitometric image analysis. Rf values of the non-polar lipids were as follows: cholesterol (0.29), free fatty acids (0.58), triacylglycerol (0.69), fatty acids methyl esters (0.84) and cholesterol ester (0.97). Rf values for the polar lipids were: cerebroside (0.42), ceramide (0.55) and cholesterol (0.73). The results showed the abundance of fatty acids methyl esters (47.75-60.46%) followed by triacylglycerol (12.69-24.14%). The remaining lipid compositions were as follows: cholesterol (4.09-13.18%), ceramide (2.18-13.27%), and cerebroside (2.53-12.81%). In conclusion, our findings showed that TLC is a simple and sensitive method for the separation and quantification of skin lipids. We also reported a new protocol for lipid extraction using the zirconia beads for efficient disruption of skin tissues. This study will help us better understand the role of skin lipids in adaptive physiology towards adverse climatic conditions. PMID:24600311

  1. Skin lipids from Saudi Arabian birds

    PubMed Central

    Khan, Haseeb A.; Arif, Ibrahim A.; Williams, Joseph B.; Champagne, Alex M.; Shobrak, Mohammad

    2013-01-01

    Skin lipids play an important role in the regulation of cutaneous water loss (CWL). Earlier studies have shown that Saudi desert birds exhibit a tendency of reduced CWL than birds from temperate environment due to adaptive changes in composition of their skin lipids. In this study, we used thin-layer chromatography (TLC) for separation and detection of non-polar and polar lipids from the skin of six bird species including sooty gull, brown booby, house sparrow, Arabian waxbill, sand partridge, and laughing dove. The lipids were separated and detected on Silica gel G coated TLC plates and quantified by using densitometric image analysis. Rf values of the non-polar lipids were as follows: cholesterol (0.29), free fatty acids (0.58), triacylglycerol (0.69), fatty acids methyl esters (0.84) and cholesterol ester (0.97). Rf values for the polar lipids were: cerebroside (0.42), ceramide (0.55) and cholesterol (0.73). The results showed the abundance of fatty acids methyl esters (47.75–60.46%) followed by triacylglycerol (12.69–24.14%). The remaining lipid compositions were as follows: cholesterol (4.09–13.18%), ceramide (2.18–13.27%), and cerebroside (2.53–12.81%). In conclusion, our findings showed that TLC is a simple and sensitive method for the separation and quantification of skin lipids. We also reported a new protocol for lipid extraction using the zirconia beads for efficient disruption of skin tissues. This study will help us better understand the role of skin lipids in adaptive physiology towards adverse climatic conditions. PMID:24600311

  2. Electrostatic modulation and enzymatic cross-linking of interfacial layers impacts gastrointestinal fate of multilayer emulsions.

    PubMed

    Zeeb, Benjamin; Weiss, Jochen; McClements, David Julian

    2015-08-01

    In this study, membrane properties were modulated using layer-by-layer electrostatic depositioning in combination with salt and/or enzyme treatment to control the gastrointestinal fate of emulsified oils. Lipid droplets coated by a single-layer of biopolymers (gelatin) were prepared by high pressure homogenization. Lipid droplets coated by a double-layer of biopolymers (gelatin-pectin) were prepared by electrostatically depositing sugar beet pectin on the gelatin-coated droplets. Laccase was added to the double-layer emulsions to covalently crosslink the adsorbed pectin molecules, whereas sodium chloride was added to modulate interfacial properties through electrostatic screening effects. Non-cross-linked and cross-linked double-layer emulsions (with and without salt) were then passed through a simulated gastrointestinal tract (GIT) that included mouth, gastric and intestinal phases. Free fatty acid release profiles suggested that the stability of the emulsified droplets within the GIT played a more important role in determining the rate and extent of lipid digestion than the initial interfacial layer properties. PMID:25766826

  3. Hydrophobic Surface Burial is the Major Stability Determinant of a Flat, Single-Layer β-Sheet

    PubMed Central

    Yan, Shude; Gawlak, Grzegorz; Makabe, Koki; Tereshko, Valentina; Koide, Akiko; Koide, Shohei

    2007-01-01

    Formation of a flat β-sheet is a fundamental event in β-sheet-mediated protein self-assembly. To investigate contributions of various factors to the stability of flat β-sheets, we performed extensive alanine-scanning mutagenesis experiments on the single-layer β-sheet segment of Borrelia outer surface protein A (OspA). This β-sheet segment consists of β-strands with highly regular geometries that can serve as a building block for self-assembly. Our Ala-scanning approach is distinct from the conventional host-guest method in that it introduces only conservative, truncation mutations that should minimize structural perturbation. Our results showed very weak correlation with experimental β-sheet propensity scales, statistical β-sheet propensity scales, or cross-strand pairwise correlations. In contrast, our data showed strong positive correlation with the change in buried nonpolar surface area. Polar interactions including prominent Glu-Lys cross-strand pairs marginally contribute to the β-sheet stability. These results were corroborated by results from additional non-Ala mutations. Taken together, these results demonstrate the dominant contribution of nonpolar surface burial to flat β-sheet stability even at solvent-exposed positions. The OspA single-layer β-sheet achieves efficient hydrophobic surface burial without forming a hydrophobic core by a strategic placement of a variety of side chains. These findings further suggest the importance of hydrophobic interactions within a β-sheet layer in peptide self-assembly. PMID:17335845

  4. Monstrous Mycobacterial Lipids.

    PubMed

    Seeliger, Jessica; Moody, D Branch

    2016-02-18

    When it comes to lipid diversity, no bacterial genus approaches Mycobacterium. In this issue of Cell Chemical Biology, Burbaud et al. (2016) provide a multi-genic working model for the biosynthesis of trehalose polyphleate (TPP), one of the largest known lipids in mycobacteria. They demonstrate that this lipid is made by diverse mycobacterial species, including those of medical importance. PMID:26971870

  5. Sodar retrieval of vertical acceleration, and implications for the determination of temperature and fluxes in the convective boundary layer

    NASA Astrophysics Data System (ADS)

    Fiocco, Giorgio; Ciminelli, Maria Grazia; Mastrantonio, Giangiuseppe

    With an array of acoustic Doppler sounders it is possible to retrieve a Lagrangian description of the air motions in the boundary layer: with adequate signal-to-noise and data processing, vertical profiles of the vertical acceleration can be obtained. In addition, by application of the buoyancy equation, the temperature and the heat flux in convective conditions can be inferred. Results of experiments carried out with three vertically pointing sodars, but with the horizontal velocity information independently provided, are shown, compared with profiles obtained with tethered balloons, and discussed.

  6. The influence of matrix composition and ink layer thickness on iron gall ink determination by the PIXE method

    NASA Astrophysics Data System (ADS)

    Uršič, Mitja; Budnar, Miloš; Simčič, Jure; Pelicon, Primož

    2006-06-01

    The elemental composition of iron gall inks in historical documents can be effectively studied using the non-destructive proton induced X-ray emission (PIXE) method. The in-air proton beam experimental set-up installed at the Microanalytical Centre of the Jožef Stefan Institute was used for this purpose. The aim of the present investigation was to model and evaluate the uncertainties in the analysis due to the incompletely known matrix composition and iron gall ink layer thickness. Estimation of these uncertainties helped in quantifying the accuracy of multi-elemental PIXE analysis of historical documents.

  7. Lipid hydroperoxides in plants.

    PubMed

    Griffiths, G; Leverentz, M; Silkowski, H; Gill, N; Sánchez-Serrano, J J

    2000-12-01

    Hydroperoxides are the primary oxygenated products of polyunsaturated fatty acids and were determined spectrophotometrically based on their reaction with an excess of Fe2+ at low pH in the presence of the dye Xylenol Orange. Triphenylphosphine-mediated hydroxide formation was used to authenticate the signal generated by the hydroperoxides. The method readily detected lipid peroxidation in a range of plant tissues including Phaseolus hypocotyls (26 +/- 5 nmol.g of fresh weight(-1); mean +/- S.D.), Alstroemeria floral tissues (sepals, 66+/-13 nmol.g of fresh weight(-1); petals, 49+/-6 nmol.g of fresh weight(-1)), potato leaves (334+/-75 nmol.g of fresh weight(-1)), broccoli florets (568+/-68 nmol.g of fresh weight(-1)) and Chlamydomonas cells (602+/-40 nmol.g of wet weight(-1)). Relative to the total fatty acid content of the tissues, the percentage hydroperoxide content was within the range of 0.6-1.7% for all tissue types (photosynthetic and non-photosynthetic) and represents the basal oxidation level of membrane fatty acids in plant cells. Leaves of transgenic potato with the fatty acid hydroperoxide lyase enzyme expressed in the antisense orientation were elevated by 38%, indicating a role for this enzyme in the maintenance of cellular levels of lipid hydroperoxides. PMID:11171226

  8. A novel double-layer molecularly imprinted polymer film based surface plasmon resonance for determination of testosterone in aqueous media

    NASA Astrophysics Data System (ADS)

    Tan, Yuan; Jing, Lijing; Ding, Yonghong; Wei, Tianxin

    2015-07-01

    This work aimed to prepare a novel double-layer structure molecularly imprinted polymer film (MIF) on the surface plasmon resonance (SPR) sensor chips for detection of testosterone in aqueous media. The film was synthesized by in-situ UV photo polymerization. Firstly, the modification of gold surface of SPR chip was performed by 1-dodecanethiol. Then double-layer MIF was generated on the 1-dodecanethiol modified gold surface. The non-modified and imprinted surfaces were characterized by atomic force microscopy (AFM), fourier transform infrared (FTIR) spectroscopy and contact angle measurements. Analysis of SPR spectroscopy showed that the imprinted sensing film displayed good selectivity for testosterone compared to other analogues and the non-imprinted polymer film (NIF). Within the concentrations range of 1 × 10-12-1 × 10-8 mol/L, the coupling angle changes of SPR were linear with the negative logarithm of testosterone concentrations (R2 = 0.993). Based on a signal/noise ratio of three, the detection limit was estimated to be 10-12 mol/L. Finally, the developed MIF was successfully applied to the seawater detection of testosterone. The results in the experiments suggested that a combination of SPR sensing with MIF was a promising alternative method for detection of testosterone in aqueous media.

  9. Determination of the shear deformation-potential constant in electron space-charge layers on Si surfaces by tunneling

    NASA Astrophysics Data System (ADS)

    Kunze, U.

    1985-10-01

    The influence of uniaxial mechanical stress on the subband structure in electron inversion layers has been studied in metal-SiO2-Si(001) junctions by means of tunneling spectroscopy. Compressive or tensile stresses applied in the [110] direction result respectively in a uniform lowering or raising of the energy of the higher primed subband system against the lower one. For stresses applied along [100] a splitting of each of the fourfold-degenerate primed levels into two levels is observed. Taking into account the bias dependence of the subband energies and the voltage drop across the channel series resistance, the tunneling characteristics yield a value for the shear deformation-potential constant Ξu=8.6+/-0.4 eV that is in accordance with the known bulk value. An extrapolation of the energy splitting between subbands belonging to the [100] and [010] valley pairs to zero stress along [100] reveals a preexisting splitting of 0.5 meV, which corresponds to a residual stress in the surface layer of 6 N mm-2.

  10. Joint French-German radar measurements for the determination of the refractive index in the maritime boundary layer

    NASA Astrophysics Data System (ADS)

    Essen, Helmut; Danklmayer, Andreas; Förster, Jörg; Behn, Mario; Hurtaud, Yvonick; Fabbro, Vincent; Castanet, Laurent

    2012-10-01

    To predict the performance of coastal and shipborne radars, it is essential to assess the propagation characteristics of electromagnetic waves in the maritime boundary layer. To be independent upon environmental measurements, which are generally not as precise and reliable as they have to be for a proper input to simulation programs, usually based upon parabolic equation models, a method to retrieve the refractive index gradients in the low troposphere is the Refractivity from Clutter (RFC) algorithm. The propagation factor is computed from the received clutter power and is iteratively processed in order to retrieve the refractive index profiles. Under a respective French-German technical agreement a measurement program concerning radar propagation in the maritime boundary layer has been initiated, with contributions from ONERA-CERT, DGA MI / TN, Fraunhofer-FHR and the German Technical Center for Ships and Naval Weapons (WTD 71). The paper gives an overview on the RFC method with examples from the previous campaigns. It describes the experimental set-up and its methodology.

  11. Photoluminescence determination of valence-band symmetry and Auger-1 threshold energy in biaxially compressed InAsSb layers

    SciTech Connect

    Kurtz, S.R.; Biefeld, R.M.; Dawson, L.R.

    1994-08-01

    InAsSb/InGaAs strained-layer superlattices (SLSs) and InAsSb quantum wells, both with biaxially compressed InAsSb layers, were characterized using magneto-photoluminescence and compared with unstained InAsSb and InAs alloys. In heterostructures with biaxially compressed InAsSb, the holes exhibited a decrease in effective mass, approaching that of the electrons. Correcting the data for the magneto-exciton binding energy, we obtain electron-hole reduced mass values in the range, {mu}=0.010--0.015, for the InAsSb heterostructures, whereas {mu}=0.026 and {mu}-0.023 for unstrained InAsSb and InAs alloys respectively. In the 2-dimensional limit, a large increase in the Auger-1 threshold energy accompanies this strain-induced change in valence-band symmetry. Correspondingly, the activation energy for nonradiative recombination in the SLSs displayed a marked increase compared with that of the unstrained alloys.

  12. Waxes: A Forgotten Topic in Lipid Teaching.

    ERIC Educational Resources Information Center

    Dominguez, Eva; Heredia, Antonio

    1998-01-01

    Reviews the biological importance of the lipids categorized as waxes and describes some of the organic chemistry of these compounds. Presents a short laboratory exercise on the extraction of plant waxes and their analysis by thin layer chromatography. (Author/CCM)

  13. Fluorometric Determination of a 1,3-Diethyl-2-thiobarbituric Acid-Malondialdehyde Adduct as an Index of Lipid Peroxidation in Plant Materials.

    PubMed

    Suda, I; Furuta, S; Nishiba, Y

    1994-01-01

    A fluorometric method has been developed to measure a 1,3-diethyl-2-thiobarbituric acid (DETBA)-malondialdehyde (MDA) adduct as an index of lipid peroxidation in plant materials. Plant tissue samples were prepared under nitrogen gas and then added to an assay system containing butylated hydroxytoluene. Following the reaction between DETBA and the plant tissue samples, the DETBA-MDA adduct was extracted with ethyl acetate and measured by spectrofluorometry or high-performance liquid chromatography (HPLC) with a fluorescence detector. The species of influencing substances with spectrofluorometry were fewer and their interfering concentration was higher than that by traditional colorimetry. When this method was applied to plant materials, the detection limits for the DETBA-MDA adduct were 2.5 nmol/g of fresh weight and 0.0625 nmol/g of fresh weight by spectrofluorometry and HPLC with a fluorescence detector, respectively. Using this sensitive, specific and simple fluorometric method, DETBA-MDA adducts ranging from 0.8 to 18.0 pmol/g of fresh weight could easily be detected from vegetables, fruits, and potatoes. PMID:27315698

  14. Determination of the structure of the O-antigen and the lipid A from the entomopathogenic bacterium Pseudomonas entomophila lipopolysaccharide along with its immunological properties.

    PubMed

    Speciale, Immacolata; Paciello, Ida; Fazio, Luigi Lembo; Sturiale, Luisa; Palmigiano, Angelo; Lanzetta, Rosa; Parrilli, Michelangelo; Garozzo, Domenico; Lemaitre, Bruno; Bernardini, Maria Lina; Molinaro, Antonio; De Castro, Cristina

    2015-08-14

    The structure and the immunology of the lipopolysaccharide (LPS) of Pseudomonas entomophila, an entomopathogenic bacterium isolated from the fruit fly Drosophila melanogaster, was characterized. The O-antigen portion was established and resulted to be built up of a repetitive unit constituted by four monosaccharide residues, all L configured, all deoxy at C-6 and with an acetamido function at C-2: →3)-α-l-FucNAc-(1→4)-α-l-FucNAc-(1→3)-α-l-FucNAc-(1→3)-β-l-QuiNAc-(1→ The structural analysis of lipid A, showed a mixture of different species. The diphosphorylated glucosamine backbone carries six fatty acids consistent with the composition C10:0 3(OH), C12:0 2(OH) and C12:0 3(OH), whereas other species differs by the number of phosphates and/or of fatty acids. The immunology experiments demonstrated that the LPS structure of P. entomophila displayed a low ability to engage the TLR4-mediated signaling correlated to a significant antagonistic activity toward hexa-acylated LPS structures. PMID:25996527

  15. Rewiring Host Lipid Metabolism by Large Viruses Determines the Fate of Emiliania huxleyi, a Bloom-Forming Alga in the Ocean[C][W][OPEN

    PubMed Central

    Rosenwasser, Shilo; Mausz, Michaela A.; Schatz, Daniella; Sheyn, Uri; Malitsky, Sergey; Aharoni, Asaph; Weinstock, Eyal; Tzfadia, Oren; Ben-Dor, Shifra; Feldmesser, Ester; Pohnert, Georg; Vardi, Assaf

    2014-01-01

    Marine viruses are major ecological and evolutionary drivers of microbial food webs regulating the fate of carbon in the ocean. We combined transcriptomic and metabolomic analyses to explore the cellular pathways mediating the interaction between the bloom-forming coccolithophore Emiliania huxleyi and its specific coccolithoviruses (E. huxleyi virus [EhV]). We show that EhV induces profound transcriptome remodeling targeted toward fatty acid synthesis to support viral assembly. A metabolic shift toward production of viral-derived sphingolipids was detected during infection and coincided with downregulation of host de novo sphingolipid genes and induction of the viral-encoded homologous pathway. The depletion of host-specific sterols during lytic infection and their detection in purified virions revealed their novel role in viral life cycle. We identify an essential function of the mevalonate-isoprenoid branch of sterol biosynthesis during infection and propose its downregulation as an antiviral mechanism. We demonstrate how viral replication depends on the hijacking of host lipid metabolism during the chemical “arms race” in the ocean. PMID:24920329

  16. Dynamic regulation of cardiolipin by the lipid pump Atp8b1 determines the severity of lung injury in experimental pneumonia.

    PubMed

    Ray, Nancy B; Durairaj, Lakshmi; Chen, Bill B; McVerry, Bryan J; Ryan, Alan J; Donahoe, Michael; Waltenbaugh, Alisa K; O'Donnell, Christopher P; Henderson, Florita C; Etscheidt, Christopher A; McCoy, Diann M; Agassandian, Marianna; Hayes-Rowan, Emily C; Coon, Tiffany A; Butler, Phillip L; Gakhar, Lokesh; Mathur, Satya N; Sieren, Jessica C; Tyurina, Yulia Y; Kagan, Valerian E; McLennan, Geoffrey; Mallampalli, Rama K

    2010-10-01

    Pneumonia remains the leading cause of death from infection in the US, yet fundamentally new conceptual models underlying its pathogenesis have not emerged. We show that humans and mice with bacterial pneumonia have markedly elevated amounts of cardiolipin, a rare, mitochondrial-specific phospholipid, in lung fluid and find that it potently disrupts surfactant function. Intratracheal cardiolipin administration in mice recapitulates the clinical phenotype of pneumonia, including impaired lung mechanics, modulation of cell survival and cytokine networks and lung consolidation. We have identified and characterized the activity of a unique cardiolipin transporter, the P-type ATPase transmembrane lipid pump Atp8b1, a mutant version of which is associated with severe pneumonia in humans and mice. Atp8b1 bound and internalized cardiolipin from extracellular fluid via a basic residue-enriched motif. Administration of a peptide encompassing the cardiolipin binding motif or Atp8b1 gene transfer in mice lessened bacteria-induced lung injury and improved survival. The results unveil a new paradigm whereby Atp8b1 is a cardiolipin importer whose capacity to remove cardiolipin from lung fluid is exceeded during inflammation or when Atp8b1 is defective. This discovery opens the door for new therapeutic strategies directed at modulating the abundance or molecular interactions of cardiolipin in pneumonia. PMID:20852622

  17. Bioactive lipid coating of bone allografts directs engraftment and fate determination of bone marrow-derived cells in rat GFP chimeras.

    PubMed

    Das, Anusuya; Segar, Claire E; Chu, Yihsuan; Wang, Tiffany W; Lin, Yong; Yang, Chunxi; Du, Xeujun; Ogle, Roy C; Cui, Quanjun; Botchwey, Edward A

    2015-09-01

    Bone grafting procedures are performed to treat wounds incurred during wartime trauma, accidents, and tumor resections. Endogenous mechanisms of repair are often insufficient to ensure integration between host and donor bone and subsequent restoration of function. We investigated the role that bone marrow-derived cells play in bone regeneration and sought to increase their contributions by functionalizing bone allografts with bioactive lipid coatings. Polymer-coated allografts were used to locally deliver the immunomodulatory small molecule FTY720 in tibial defects created in rat bone marrow chimeras containing genetically-labeled bone marrow for monitoring cell origin and fate. Donor bone marrow contributed significantly to both myeloid and osteogenic cells in remodeling tissue surrounding allografts. FTY720 coatings altered the phenotype of immune cells two weeks post-injury, which was associated with increased vascularization and bone formation surrounding allografts. Consequently, degradable polymer coating strategies that deliver small molecule growth factors such as FTY720 represent a novel therapeutic strategy for harnessing endogenous bone marrow-derived progenitors and enhancing healing in load-bearing bone defects. PMID:26125501

  18. Rewiring Host Lipid Metabolism by Large Viruses Determines the Fate of Emiliania huxleyi, a Bloom-Forming Alga in the Ocean.

    PubMed

    Rosenwasser, Shilo; Mausz, Michaela A; Schatz, Daniella; Sheyn, Uri; Malitsky, Sergey; Aharoni, Asaph; Weinstock, Eyal; Tzfadia, Oren; Ben-Dor, Shifra; Feldmesser, Ester; Pohnert, Georg; Vardi, Assaf

    2014-06-10

    Marine viruses are major ecological and evolutionary drivers of microbial food webs regulating the fate of carbon in the ocean. We combined transcriptomic and metabolomic analyses to explore the cellular pathways mediating the interaction between the bloom-forming coccolithophore Emiliania huxleyi and its specific coccolithoviruses (E. huxleyi virus [EhV]). We show that EhV induces profound transcriptome remodeling targeted toward fatty acid synthesis to support viral assembly. A metabolic shift toward production of viral-derived sphingolipids was detected during infection and coincided with downregulation of host de novo sphingolipid genes and induction of the viral-encoded homologous pathway. The depletion of host-specific sterols during lytic infection and their detection in purified virions revealed their novel role in viral life cycle. We identify an essential function of the mevalonate-isoprenoid branch of sterol biosynthesis during infection and propose its downregulation as an antiviral mechanism. We demonstrate how viral replication depends on the hijacking of host lipid metabolism during the chemical "arms race" in the ocean. PMID:24920329

  19. A simple method for the determination of the complex modulus of resilient materials using a longitudinally vibrating three-layer specimen

    NASA Astrophysics Data System (ADS)

    Policarpo, H.; Neves, M. M.; Maia, N. M. M.

    2013-01-01

    This paper proposes a new hybrid analytical-experimental methodology for the determination of the complex modulus of resilient materials as for e.g., composition cork-like materials. It is based on a three-layer specimen test and on a simple equation from the analytical model of the specimen. The analytical formulation solves the problem based on the elementary theory of longitudinal vibrations and without taking the transversal motions into account. This methodology is developed to avoid geometric constraints and boundary condition difficulties found on other tests as well as to minimize the computational time and complexity of the coding. The experimental setup and the deduction of the simple equation are described. Metallic layers are used at the extremities of the specimen, for which the Young modulus and mass density are known, while its loss factor may be neglected. For the intermediate resilient layer, which is assumed to present a linear viscoelastic behavior, the mass density is known. Thus, the only unknowns are the storage modulus and loss factor of that intermediate layer. The modal loss factor and the first resonant frequency of the specimen are identified from the experimental receptance frequency response function (FRF) curve using the rational fraction polynomial method (RFP). By using the first resonance frequency obtained experimentally, the analytical response becomes only a function of the storage modulus, resulting in a simple scalar nonlinear equation. Then, a numerical routine is used to determine the storage modulus by calculating the first zero of the nonlinear equation. To validate the proposed methodology, the frequency response assurance criterion (FRAC) and the frequency amplitude assurance criterion (FAAC) are used. For the five composition cork materials tested, the complex modulus shown low frequency dependence in the 40 Hz to 1600 Hz range. Correlation values between the analytical and the experimental curves are greater than 95

  20. Molecular Dynamics Simulation Study of Permeation of Molecules through Skin Lipid Bilayer.

    PubMed

    Gupta, Rakesh; Sridhar, D B; Rai, Beena

    2016-09-01

    Stratum Corneum (SC), the outermost layer of skin, is mainly responsible for skin's barrier function. The complex lipid matrix of SC determines these barrier properties. In this study, the lipid matrix is modeled as an equimolar mixture of ceramide (CER), cholesterol (CHOL), and free fatty acid (FFA). The permeation of water, oxygen, ethanol, acetic acid, urea, butanol, benzene, dimethyl sulfoxide (DMSO), toluene, phenol, styrene, and ethylbenzene across this layer is studied using a constrained MD simulations technique. Several long constrained simulations are performed at a skin temperature of 310 K under NPT conditions. The free energy profiles and diffusion coefficients along the bilayer normal have been calculated for each molecule. Permeability coefficients are also calculated and compared with experimental data. The main resistance for the permeation of hydrophilic and hydrophobic permeants has been found to be in the interior of the lipid bilayer and near the lipid-water interface, respectively. The obtained permeability is found to be a few orders of magnitude higher than experimental values for hydrophilic molecules while for hydrophobic molecules more discrepancy was observed. Overall, the qualitative ranking is consistent with the experiments. PMID:27518707

  1. Validation Thin Layer Chromatography for the Determination of Acetaminophen in Tablets and Comparison with a Pharmacopeial Method

    PubMed Central

    Pyka, Alina; Budzisz, Marika; Dołowy, Małgorzata

    2013-01-01

    Adsorption thin layer chromatography (NP-TLC) with densitometry has been established for the identification and the quantification of acetaminophen in three leading commercial products of pharmaceutical tablets coded as brand: P1 (Product no. 1), P2 (Product no. 2), and P3 (Product no. 3). Applied chromatographic conditions have separated acetaminophen from its related substances, namely, 4-aminophenol and and 4′-chloroacetanilide. UV densitometry was performed in absorbance mode at 248 nm. The presented method was validated by specificity, range, linearity, accuracy, precision, detection limit, quantitative limit, and robustness. The TLC-densitometric method was also compared with a pharmacopeial UV-spectrophotometric method for the assay of acetaminophen, and the results confirmed statistically that the NP-TLC-densitometric method can be used as a substitute method. It could be said that the validated NP-TLC-densitometric method is suitable for the routine analysis of acetaminophen in quantity control laboratories. PMID:24063006

  2. C and N depth profiles of SiCN layers determined with nuclear reaction analyses and AES

    NASA Astrophysics Data System (ADS)

    Link, F.; Baumann, H.; Bethge, K.; Klewe-Nebenius, H.; Bruns, M.

    1998-04-01

    Si 1C xN y layers were prepared by sequential implantation of 40 keV 13C- and 50 keV 15N-ions into c-Si <1 1 1> samples near RT. The carbon and nitrogen depth distributions were measured using the resonant nuclear (p,γ) reactions 15N(p,αγ) 12C at Eres=429 keV and 13C(p,γ) 14N at Eres=1748 keV, respectively. The measured raw data of depth profiling (gamma yield versus the proton beam energy) are converted to concentration-depth profiles of the elements C, N and Si with a common depth scale by using a new developed computer algorithm. These concentration profiles are compared with those obtained with Auger Electron Spectroscopy (AES) and non-Rutherford Backscattering Spectrometry (n-RBS).

  3. Nutrients and neurodevelopment: lipids.

    PubMed

    González, Horacio F; Visentin, Silvana

    2016-10-01

    Nutrients, lipids in particular, make up the central nervous system structure and play major functional roles: they stimulate development, migration, and nerve cell differentiation. They are part of gray matter, white matter, nerve nuclei, and synaptogenesis. Breast milk contains lipids which are crucial for infant brain development. The lipid profile of breast milk was used as a guideline for the development of breast milk substitutes. However, to date, no substitute has matched it. Complementary feeding should include docosahexaenoic acid, arachidonic acid, other polyunsaturated fatty acids, saturated fatty acids, and complex lipids found in milk fat. The lipid composition of breast milk depends on maternal intake and nutritional status during pregnancy and breast-feeding. It has a great impact on development. Our goal is to review scientific literature regarding the role of lipids on infant brain development and the importance of breast milk lipid composition, maternal diet, and complementary feeding. PMID:27606648

  4. Isolation of Cellular Lipid Droplets: Two Purification Techniques Starting from Yeast Cells and Human Placentas

    PubMed Central

    Dalhaimer, Paul

    2014-01-01

    Lipid droplets are dynamic organelles that can be found in most eukaryotic and certain prokaryotic cells. Structurally, the droplets consist of a core of neutral lipids surrounded by a phospholipid monolayer. One of the most useful techniques in determining the cellular roles of droplets has been proteomic identification of bound proteins, which can be isolated along with the droplets. Here, two methods are described to isolate lipid droplets and their bound proteins from two wide-ranging eukaryotes: fission yeast and human placental villous cells. Although both techniques have differences, the main method - density gradient centrifugation - is shared by both preparations. This shows the wide applicability of the presented droplet isolation techniques. In the first protocol, yeast cells are converted into spheroplasts by enzymatic digestion of their cell walls. The resulting spheroplasts are then gently lysed in a loose-fitting homogenizer. Ficoll is added to the lysate to provide a density gradient, and the mixture is centrifuged three times. After the first spin, the lipid droplets are localized to the white-colored floating layer of the centrifuge tubes along with the endoplasmic reticulum (ER), the plasma membrane, and vacuoles. Two subsequent spins are used to remove these other three organelles. The result is a layer that has only droplets and bound proteins. In the second protocol, placental villous cells are isolated from human term placentas by enzymatic digestion with trypsin and DNase I. The cells are homogenized in a loose-fitting homogenizer. Low-speed and medium-speed centrifugation steps are used to remove unbroken cells, cellular debris, nuclei, and mitochondria. Sucrose is added to the homogenate to provide a density gradient and the mixture is centrifuged to separate the lipid droplets from the other cellular fractions. The purity of the lipid droplets in both protocols is confirmed by Western Blot analysis. The droplet fractions from both preps

  5. Densitometric thin-layer chromatographic determination of aescin in a herbal medicinal product containing Aesculus and Vitis dry extracts.

    PubMed

    Apers, Sandra; Naessens, Tania; Pieters, Luc; Vlietinck, Arnold

    2006-04-21

    A thin-layer chromatographic (TLC) method is developed to analyze the total saponin content, also referred to as the aescin content, in a herbal medicinal product (HMP) containing two dry extracts in capsules. The capsules contain 250 mg of Aesculus hippocastanum dry extract, 120 mg of Vitis vinifera dry extract and 50mg of excipients. After a purification step using C(18) solid phase extraction (SPE) cartridges, the samples are analyzed on a silica-gel HPTLC plate with the upper layer of a mixture of acetic acid/water/butanol (10/40/50 v/v/v) as the mobile phase. Spots are visualized by spraying with anisaldehyde reagent and heating the plate for 5-10 min (100-105 degrees C) and measured at a wavelength of 535 nm. This method, applicable for the quality control and stability investigation of both the Aesculus dry extract and HMP capsules thereof containing Vitis dry extract in combination with the Aesculus dry extract, is validated according to the International Conference on Harmonization (ICH) guidelines. The proposed assay method is specific for aescin in the presence of Vitis dry extract and formulation excipients. Analysis of stressed samples in forced degradation tests proves the method to be applicable for stability evaluation. The standard aescin curve is linear (r > 0.99) over a concentration range of 0.16-0.80 microg/spot. Recovery from the HMP capsules is statistically equal to 100%. The precision of the method with respect to time and concentration is acceptable, with relative standard deviation (RSD) values of 1.28 and 1.49%, respectively. PMID:16364347

  6. Using of standard marine radar for determination of a water surface and an atmosphere near-surface layer parameters

    NASA Astrophysics Data System (ADS)

    Bogatov, Nikolay A.; Bakhanov, Victor V.; Ermoshkin, Aleksei V.; Kazakov, Vasily I.; Kemarskaya, Olga N.; Titov, Victor I.; Troitskaya, Yulia I.

    2014-10-01

    At present time radar methods of the seas and oceans diagnostics are actively developing. Using of the radar stations based on satellites and planes allows to receive information on a sea surface and a atmosphere near-surface layer with coverage of big water surface areas independently of day time. The developed methods of satellite radio images processing can be applied to marine radar stations. In Institute of Applied Physics RAS works on sea surface diagnostics systems development on the basis of standard marine radar are actively conducted. Despite smaller coverage of the territory in comparison with satellite data, marine radar have possibility to record spatially temporary radar images and to receive information on a surrounding situation quickly. This work deals with results of the researches which were conducted within the international expedition in the Atlantic Ocean in the autumn of 2012 on a route Rotterdam (Netherlands) - Ushuaya (Argentina) - Antarctica — Ushuaya. During this expedition a complex measurements of a sea surface, a atmosphere near-surface layer parameters and subsurface currents in the wide range of hydroweather conditions, including the storm were carried out. The system developed in IAP RAS on the basis of a marine radar ICOM MR-1200RII and the ADC (Analog Digital Converter) block for data recording on the personal computer was used. Display of a non-uniform near-surface current on sea surface radar images in storm conditions is shown. By means of the high-speed anemometer and meteorological station the measurements of the atmosphere parameters were carried out. Comparison of the anemometer data with calculated from radar images is carried out. Dependence of radar cross section from wind speed in the wide range of wind speeds, including storm conditions is investigated. Possibility of marine radar using for surface waves intensity and ice situation estimates also as icebergs detection is shown.

  7. X-ray attenuation measurements in a cavitating mixing layer for instantaneous two-dimensional void ratio determination

    SciTech Connect

    Aeschlimann, Vincent; Barre, Stephane; Legoupil, Samuel

    2011-05-15

    The purpose of this experimental study was to analyze a two-dimensional cavitating shear layer. The global aim of this work was to obtain a better understanding and modeling of cavitation phenomenon in a 2D turbulent sheared flow which can be considered as quite representative of cavitating rocket engine turbopomp inducers. This 2D mixing layer flow provided us a well documented test case which can be used for the characterization of the cavitation effects in sheared flows. The development of a velocity gradient was observed inside a liquid water flow: Kelvin-Helmholtz instabilities developed at the interface. Vaporizations and implosions of cavitating structures inside the vortices were observed. X-ray attenuation measurements were performed to estimate the amount of vapor present inside the mixing area. Instantaneous two-dimensional void ratio fields were acquired. The real spatial resolutions are 0.5 mm with 2000 fps and 1.5 mm with 20 000 fps. The effective time resolution is equal to the camera frame rate up to a 19% void ratio variation between two consecutive images. This seems to be sufficient in the context of the present flow configuration. The two-phase structures present inside the mixing area were analyzed at three different cavitation levels and their behaviors were compared to non-cavitating flow dynamic. Convection velocities and vortices shedding frequencies were estimated. Results show that vapor was transported by the turbulent velocity field. Statistical analysis of the void ratio signal was carried out up to the fourth order moment. This study provided a global understanding of the cavitating structure evolution and of the cavitation effects on turbulent sheared flows.

  8. Crystallization modifiers in lipid systems.

    PubMed

    Ribeiro, Ana Paula Badan; Masuchi, Monise Helen; Miyasaki, Eriksen Koji; Domingues, Maria Aliciane Fontenele; Stroppa, Valter Luís Zuliani; de Oliveira, Glazieli Marangoni; Kieckbusch, Theo Guenter

    2015-07-01

    Crystallization of fats is a determinant physical event affecting the structure and properties of fat-based products. The stability of these processed foods is regulated by changes in the physical state of fats and alterations in their crystallization behavior. Problems like polymorphic transitions, oil migration, fat bloom development, slow crystallization and formation of crystalline aggregates stand out. The change of the crystallization behavior of lipid systems has been a strategic issue for the processing of foods, aiming at taylor made products, reducing costs, improving quality, and increasing the applicability and stability of different industrial fats. In this connection, advances in understanding the complex mechanisms that govern fat crystallization led to the development of strategies in order to modulate the conventional processes of fat structuration, based on the use of crystallization modifiers. Different components have been evaluated, such as specific triacyglycerols, partial glycerides (monoacylglycerols and diacylglycerols), free fatty acids, phospholipids and emulsifiers. The knowledge and expertise on the influence of these specific additives or minor lipids on the crystallization behavior of fat systems represents a focus of current interest for the industrial processing of oils and fats. This article presents a comprehensive review on the use of crystallization modifiers in lipid systems, especially for palm oil, cocoa butter and general purpose fats, highlighting: i) the removal, addition or fractionation of minor lipids in fat bases; ii) the use of nucleating agents to modify the crystallization process; iii) control of crystallization in lipid bases by using emulsifiers. The addition of these components into lipid systems is discussed in relation to the phenomena of nucleation, crystal growth, morphology, thermal behavior and polymorphism, with the intention of providing the reader with a complete panorama of the associated mechanisms

  9. Lipid metabolic reprogramming in cancer cells

    PubMed Central

    Beloribi-Djefaflia, S; Vasseur, S; Guillaumond, F

    2016-01-01

    Many human diseases, including metabolic, immune and central nervous system disorders, as well as cancer, are the consequence of an alteration in lipid metabolic enzymes and their pathways. This illustrates the fundamental role played by lipids in maintaining membrane homeostasis and normal function in healthy cells. We reviewed the major lipid dysfunctions occurring during tumor development, as determined using systems biology approaches. In it, we provide detailed insight into the essential roles exerted by specific lipids in mediating intracellular oncogenic signaling, endoplasmic reticulum stress and bidirectional crosstalk between cells of the tumor microenvironment and cancer cells. Finally, we summarize the advances in ongoing research aimed at exploiting the dependency of cancer cells on lipids to abolish tumor progression. PMID:26807644

  10. Caenorhabditis elegans as an alternative in vivo model to determine oral uptake, nanotoxicity, and efficacy of melatonin-loaded lipid-core nanocapsules on paraquat damage

    PubMed Central

    Charão, Mariele Feiffer; Souto, Caroline; Brucker, Natália; Barth, Anelise; Jornada, Denise S; Fagundez, Daiandra; Ávila, Daiana Silva; Eifler-Lima, Vera L; Guterres, Silvia S; Pohlmann, Adriana R; Garcia, Solange Cristina

    2015-01-01

    Caenorhabditis elegans is an alternative in vivo model that is being successfully used to assess the pharmacological and toxic effects of drugs. The exponential growth of nanotechnology requires the use of alternative in vivo models to assess the toxic effects of theses nanomaterials. The use of polymeric nanocapsules has shown promising results for drug delivery. Moreover, these formulations have not been used in cases of intoxication, such as in treatment of paraquat (PQ) poisoning. Thus, the use of drugs with properties improved by nanotechnology is a promising approach to overcome the toxic effects of PQ. This research aimed to evaluate the absorption of rhodamine B-labeled melatonin (Mel)-loaded lipid-core nanocapsules (LNC) by C. elegans, the application of this model in nanotoxicology, and the protection of Mel-LNC against PQ damage. The formulations were prepared by self-assembly and characterized by particle sizing, zeta potential, drug content, and encapsulation efficiency. The results demonstrated that the formulations had narrow size distributions. Rhodamine B-labeled Mel-LNC were orally absorbed and distributed in the worms. The toxicity assessment of LNC showed a lethal dose 50% near the highest dose tested, indicating low toxicity of the nanocapsules. Moreover, pretreatment with Mel-LNC significantly increased the survival rate, reduced the reactive oxygen species, and maintained the development in C. elegans exposed to PQ compared to those worms that were either untreated or pretreated with free Mel. These results demonstrated for the first time the uptake and distribution of Mel-LNC by a nematode, and indicate that while LNC is not toxic, Mel-LNC prevents the effects of PQ poisoning. Thus, C. elegans may be an interesting alternative model to test the nanocapsules toxicity and efficacy. PMID:26300641

  11. Near infrared Raman spectra of human brain lipids

    NASA Astrophysics Data System (ADS)

    Krafft, Christoph; Neudert, Lars; Simat, Thomas; Salzer, Reiner

    2005-05-01

    Human brain tissue, in particular white matter, contains high lipid content. These brain lipids can be divided into three principal classes: neutral lipids including the steroid cholesterol, phospholipids and sphingolipids. Major lipids in normal human brain tissue are phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol, phosphatidic acid, sphingomyelin, galactocerebrosides, gangliosides, sulfatides and cholesterol. Minor lipids are cholesterolester and triacylglycerides. During transformation from normal brain tissue to tumors, composition and concentration of lipids change in a specific way. Therefore, analysis of lipids might be used as a diagnostic parameter to distinguish normal tissue from tumors and to determine the tumor type and tumor grade. Raman spectroscopy has been suggested as an analytical tool to detect these changes even under intra-operative conditions. We recorded Raman spectra of the 12 major and minor brain lipids with 785 nm excitation in order to identify their spectral fingerprints for qualitative and quantitative analyses.

  12. Functional One-Dimensional Lipid Bilayers on Carbon Nanotube Templates

    SciTech Connect

    Artyukhin, A; Shestakov, A; Harper, J; Bakajin, O; Stroeve, P; Noy, A

    2004-07-23

    We present one-dimensional (1-D) lipid bilayer structures that integrate carbon nanotubes with a key biological environment-phospholipid membrane. Our structures consist of lipid bilayers wrapped around carbon nanotubes modified with a hydrophilic polymer cushion layer. Despite high bilayer curvature, the lipid membrane maintains its fluidity and can sustain repeated damage-recovery cycles. We also present the first evidence of spontaneous insertion of pore-forming proteins into 1-D lipid bilayers. These structures could lead to the development of new classes of biosensors and bioelectronic devices.

  13. Determining Boundary Layer Mixing State based on NASA DISCOVER-AQ Airborne Soundings over the Baltimore/Washington Area

    NASA Astrophysics Data System (ADS)

    Chen, G.; Crawford, J. H.; Silverman, M. L.; Anderson, B. E.; Barrick, J. D.; Diskin, G. S.; Fried, A.; Yang, M. M.; Weinheimer, A. J.; Lenschow, D. H.

    2012-12-01

    The DISCOVER-AQ (Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality) mission conducted its first field deployment in the Washington D.C./Baltimore region during July 2011. The overarching goal is to better understand how remotely-sensed column measurements can be used to diagnose near-surface air quality. To achieve this objective, the DISCOVER-AQ sampling strategy requires extensive probing of the vertical structure of the lower troposphere as it relates to both trace gases and aerosols. This strategy was implemented by using the NASA P-3B aircraft to spiral from 0.3 to ~3 km over 6 MDE (Maryland Department of the Environment) ground monitoring sites. A total of 254 spirals were flown which generated detailed vertical distributions for a large variety of trace gases, aerosol properties, and meteorological variables. This data set allows a detailed assessment of vertical mixing state, which can be estimated by the changes of the measured variables with height within the boundary layer. The data set was further filtered to minimize the influence of the horizontal inhomogeneity. To be presented are cases under different atmospheric stability classes to show the actual observed atmospheric structure and vertical distributions of the aerosols and trace gases which have a wide range of lifetimes.

  14. Specific binding of adamantane drugs and direction of their polar amines in the pore of the influenza M2 transmembrane domain in lipid bilayers and dodecylphosphocholine micelles determined by NMR spectroscopy.

    PubMed

    Cady, Sarah D; Wang, Jun; Wu, Yibing; DeGrado, William F; Hong, Mei

    2011-03-30

    The transmembrane domain of the influenza M2 protein (M2TM) forms a tetrameric proton channel important for the virus lifecycle. The proton-channel activity is inhibited by amine-containing adamantyl drugs amantadine and rimantadine, which have been shown to bind specifically to the pore of M2TM near Ser31. However, whether the polar amine points to the N- or C-terminus of the channel has not yet been determined. Elucidating the polar group direction will shed light on the mechanism by which drug binding inhibits this proton channel and will facilitate rational design of new inhibitors. In this study, we determine the polar amine direction using M2TM reconstituted in lipid bilayers as well as dodecylphosphocholine (DPC) micelles. (13)C-(2)H rotational-echo double-resonance NMR experiments of (13)C-labeled M2TM and methyl-deuterated rimantadine in lipid bilayers showed that the polar amine pointed to the C-terminus of the channel, with the methyl group close to Gly34. Solution NMR experiments of M2TM in DPC micelles indicate that drug binding causes significant chemical shift perturbations of the protein that are very similar to those seen for M2TM and M2(18-60) bound to lipid bilayers. Specific (2)H-labeling of the drugs permitted the assignment of drug-protein cross peaks, which indicate that amantadine and rimantadine bind to the pore in the same fashion as for bilayer-bound M2TM. These results strongly suggest that adamantyl inhibition of M2TM is achieved not only by direct physical occlusion of the channel, but also by perturbing the equilibrium constant of the proton-sensing residue His37. The reproduction of the pharmacologically relevant specific pore-binding site in DPC micelles, which was not observed with a different detergent, DHPC, underscores the significant influence of the detergent environment on the functional structure of this membrane protein. PMID:21381693

  15. Structural investigation of the covalent and electrostatic binding of yeast cytochrome c to the surface of various ultrathin lipid multilayers using x-ray diffraction.

    PubMed Central

    Pachence, J M; Blasie, J K

    1991-01-01

    X-Ray diffraction was used to characterize the profile structures of ultrathin lipid multilayers having a bound surface layer of cytochrome c. The lipid multilayers were formed on an alkylated glass surface, using the Langmuir-Blodgett method. The ultrathin lipid multilayers of this study were: five monolayers of arachidic acid, four monolayers of arachidic acid with a surface monolayer of dimyristoyl phosphatidylserine, and four monolayers of arachidic acid acid with a surface monolayer of thioethyl stearate. Both the phosphatidylserine and the thioethyl stearate surfaces were found previously to covalently bind yeast cytochrome c, while the arachidic acid surface electrostatically binds yeast cytochrome c. Meridional x-ray diffraction data were collected from these lipid multilayer films with and without a bound yeast cytochrome c surface layer. A box refinement technique, previously shown to be effective in deriving the profile structures of ultrathin multilayer lipid films with and without electrostatically bound cytochrome c, was used to determine the multilayer electron density profiles. The surface monolayer of bound cytochrome c was readily apparent upon comparison of the multilayer electron density profiles for the various pairs of ultrathin multilayer films plus/minus cytochrome c for all cases. In addition, cytochrome c binding to the multilayer surface significantly perturbs the underlying lipid monolayers. PMID:1648415

  16. Comparison of thickness, grade, and depth of radioactive layers as determined by gamma-ray logging and by core sampling

    USGS Publications Warehouse

    Bunker, Carl M.

    1959-01-01

    Thickness, grade, and depth data were obtained by analyzing gamma-ray logs and core samples from 56 diamond drill holes penetrating uranium deposits in the Colorado Plateau. The data from the two methods were compared to determine variations found in gamma-ray log interpretation and chemical and radiometric analyses of the drill core. Correlations within each parameter varied among the drilling areas analyzed. Gamma-ray interpretations of grade compared to chemical analyses were within the range of -10 to +25 percent. Most depth measurements determined by gamma-ray log interpretation compared to drill core measurement were within 0.5 percent. Results of the study indicate a need for better thickness definition in both gamma-ray logging and core scanning equipment.

  17. Restoration of stratum corneum with nacre lipids.

    PubMed

    Rousseau, Marthe; Bédouet, Laurent; Lati, Elian; Gasser, Philippe; Le Ny, Karine; Lopez, Evelyne

    2006-09-01

    To discover potential new products for the atopic dermatitis treatment, lipids extracted from nacre from the oyster Pinctada margaritifera were tested on artificially dehydrated skin explants. Expression of filaggrin and transglutaminase 1 was investigated after treatment of dehydrated skin with P. margaritifera lipid extracts according to light microscopy after labelling with specific monoclonal antibodies. The lipids were extracted from the nacre with methanol/chloroform mixture at room temperature and the extract composition was determined according to TLC and densitometry measures. Relative to the dry nacre material, a yield of extraction in lipids of 0.54% (w/w) was determined. Fatty acids, triglycerides, cholesterol and ceramides were in low abundance. Then, application of lipid formulations on skin explants previously dehydrated gave after 3 h an overexpression of filaggrin and a decrease of transglutaminase expression as shown by light microscopy. Using immunofluorescence labelling, we showed that lipids extracted from the mother of pearl of P. margaritifera induced a reconstitution of the intercellular cement of the stratum corneum. The signaling properties of the nacre lipids could be used for a development of new active product treatment against the symptoms of the dermatitis. PMID:16877020

  18. The determination and quantification of photosynthetic pigments by reverse phase high-performance liquid chromatography, thin-layer chromatography, and spectrophotometry.

    PubMed

    Pocock, Tessa; Król, Marianna; Huner, Norman P A

    2004-01-01

    Chorophylls and carotenoids are functionally important pigment molecules in photosynthetic organisms. Methods for the determination of chlorophylls a and b, beta-carotene, neoxanthin, and the pigments that are involved in photoprotective cycles such as the xanthophylls are discussed. These cycles involve the reversible de-epoxidation of violaxanthin into antheraxanthin and zeaxanthin, as well as the reversible de-epoxidation of lutein-5,6-epoxide into lutein. This chapter describes pigment extraction procedures from higher plants and green algae. Methods for the determination and quantification using high-performance liquid chromatograpy (HPLC) are described as well as methods for the separation and purification of pigments for use as standards using thin-layer chromatography (TLC). In addition, several spectrophotometric methods for the quantification of chlorophylls a and b are described. PMID:15187276

  19. Molecular Delivery into a Lipid Bilayer with a Single Shock Waves Using Molecular Dynamic Simulation

    NASA Astrophysics Data System (ADS)

    Koshiyama, Kenichiro; Kodama, Tetsuya; Hamblin, Michael R.; Doukas, Apostolos G.; Yano, Takeru; Fujikawa, Shigeo

    2005-03-01

    Cell permeabilization by shock waves may have application in gene therapy and anticancer drug delivery. In the present study we performed direct molecular dynamic (MD) simulation of the interaction of a single shock wave with a cell membrane to investigate the mechanism of the cell permeabilization. The shock wave was characterized by an impulse that was expressed with a velocity determined by the change in the momentum. The cell membrane was designed as a dipalmitoylphosphatidylcholine (DPPC) lipid bilayer placed between two layers of water molecules. The MD simulation determined the relationship between water penetration into the bilayer, the order parameter, the fluidity of each lipid molecule, and the intensity of impulse. These structural changes in the bilayer may be an important factor in the use of shock waves to produce transient membrane permeability.

  20. Percutaneous absorption of steroids: determination of in vitro permeability and tissue reservoir characteristics in human skin layers.

    PubMed

    Magnusson, B M; Cross, S E; Winckle, G; Roberts, M S

    2006-01-01

    The skin localization of steroids following topical application is largely unknown. We determined the distribution of five steroids in human skin using excised epidermal, dermal, and full-thickness membranes in vitro. There was no significant difference in steroid maximum flux through epidermal and full-thickness membranes, other than significantly lower fluxes for the most polar steroid, aldosterone. Hydrocortisone had the highest dermal diffusivity and dermal penetration, and the accumulation of hydrocortisone and corticosterone was higher than that of the other steroids. Slower penetration and higher accumulation in the viable epidermis of progesterone in full-thickness skin were consistent with dermal penetration limitation effects associated with high lipophilicity. PMID:16931901

  1. Rhodopsin-lipid interactions studied by NMR.

    PubMed

    Soubias, Olivier; Gawrisch, Klaus

    2013-01-01

    The biophysical properties of the lipid matrix are known to influence function of integral membrane proteins. We report on a sample preparation method for reconstitution of membrane proteins which uses porous anodic aluminum oxide (AAO) filters with 200-nm-wide pores of high density. The substrate permits formation of tubular, single membranes that line the inner surface of pores. One square centimeter of filter with a thickness of 60μm yields on the order of 500cm(2) of solid-supported single bilayer surface, sufficient for NMR studies. The tubular bilayers are free of detergent, fully hydrated, and accessible for ligands from one side of the membrane. The use of AAO filters greatly improves reproducibility of the reconstitution process such that the influence of protein on lipid order parameters can be studied with high resolution. As an example, results for the G protein-coupled receptor of class A, bovine rhodopsin, are shown. By (2)H NMR order parameter measurements, it is detected that rhodopsin insertion elastically deforms membranes near the protein. Furthermore, by (1)H saturation-transfer NMR under conditions of magic angle spinning, we demonstrate detection of preferences in interactions of rhodopsin with particular lipid species. It is assumed that function of integral membrane proteins depends on both protein-induced elastic deformations of the lipid matrix and preferences for interaction of the protein with particular lipid species in the first layer of lipids surrounding the protein. PMID:23374188

  2. Purification of vetiver alcohols and esters for quantitative high-performance thin-layer chromatography determination in Haitian vetiver essential oils and vetiver acetates.

    PubMed

    Paillat, Lionel; Périchet, Christine; Pierrat, Jean-Philippe; Lavoine, Sophie; Filippi, Jean-Jacques; Meierhenrich, Uwe; Fernandez, Xavier

    2012-06-01

    A simple, fast, and efficient High-Performance Thin-Layer Chromatography (HPTLC) method was developed for the simultaneous quantitative determination of alcohols and acetates in Haitian vetiver essential oils (Chryzopogon zizanioides) and its acetylated form. Analytes were separated by using a mixture of n-hexane-chloroform-ethyl acetate (8:6:0.5, v/v/v) as mobile phase under 47% humidity. Quantification was achieved by densitometric evaluation of the analytes in absorbance mode under visible light (λ=530 nm) after staining with a vanillin-sulfuric acid reagent. Reference mixtures of alcohols and acetates were obtained by fractionation of Haitian vetiver oil or vetiver acetates, followed by purification of the fractions of interest by means of Over-Pressured Layer Chromatography (OPLC). The chemical composition of each reference fraction was determined by using GC-MS and GC×GC-MS, and their overall purity was determined by GC/FID and HPTLC. The TLC method provided compact spots for alcohols (R(f2)=0.18±0.01 and R(f1)=0.28±0.01) and acetates (R(f3)=0.65±0.01). Calibration plots showed good linear correlation with r²=0.9995±0.0001 and r²=0.9995±0.0001 for alcohols and r²=0.9996±0.0001 for acetates in a 40-200 ng spot⁻¹ concentration range with respect to peak areas. The method was validated for precision and accuracy. Limit of detection (LOD) and quantification (LOQ) were determined. Method specificity was confirmed using retention factor (R(f)) and GC-MS control of the standards reference mixtures. PMID:22560705

  3. Optical and chemical properties of marine boundary-layer aerosol around Japan determined from shipboard measurements in 2002

    NASA Astrophysics Data System (ADS)

    Shiobara, Masataka; Hara, Keiichiro; Yabuki, Masanori; Kobayashi, Hiroshi

    Shipboard measurements of the optical and chemical properties of marine boundary-layer aerosol were made around Japan over the period from 28 August to 25 September 2002. Measurements were conducted aboard the Research Vessel (R/V) Shirase along cruise tracks beginning from Yokosuka, and proceeding on to Hakodate, Sakata, Sasebo, Naha, Kure, and Yokkaichi. This paper describes the results of optical measurements using an Optical Particle Counter (OPC), an Integrating Nephelometer (IN), and a Particle Soot/Absorption Photometer (PSAP), as well as chemical analyses of water-soluble aerosol particles collected by impactor and filter systems. Coulter Multisizer measurements were used for water-insoluble aerosol particles. The complex refractive index (CRI), scattering and absorption coefficients, and size distribution of aerosols were estimated from combined measurements made using OPC, IN, and PSAP. Contrasting aerosol characteristics were observed during different stages of the cruise. Discussion on these differences focuses mainly on two legs: Leg-1 from Yokosuka to Hakodate and Leg-4 from Sasebo to Naha. Backward trajectory analyses indicate that the air sampled during Leg-1 originated from the Pacific Ocean, whereas the air sampled during Leg-4 originated from the Chinese Continent via the Korean Peninsula. For the first half of Leg-1, the number concentration was low and larger particles were relatively predominant. The real and imaginary parts of the CRI were estimated to be 1.38-1.40 and close to zero, respectively. This estimation is consistent with the results of chemical analyses, which show that the sea salt is rich in aerosols sourced from remote ocean areas. In contrast, small particles were predominant during Leg-4, and the real and imaginary parts of the CRI were estimated to be 1.52-1.59 and approximately -0.002, respectively. These findings are also consistent with chemical analyses that reveal a mixture of mineral dust and sulfate aerosol likely

  4. Lipid accumulation in prosthetic vascular grafts. Experimental study.

    PubMed Central

    Chignier, E.; Guidollet, J.; Lhopital, C.; Louisot, P.; Eloy, R.

    1990-01-01

    The present study demonstrates that the endoprosthetic tissue, developed at the contact of Dacron and Gore-Tex vascular prostheses replacing the infrarenal aortae of healthy dogs, presents a particular lipidic pattern as compared with the adjacent intimal arterial layer. The modified lipidic pattern is characterized by a significant increase in the total amounts of cholesterol, phospholipids, and triglycerides, despite a normal lipidic plasma profile. Histochemical studies showed that lipid droplets are accumulated in the cytoplasm of deeply situated cells and in the extracellular matrix. These findings support the idea that lipids may be trapped within the pseudo-intima of synthetic vascular grafts, even in the absence of a major plasma lipid disorder, and contribute to the prosthesis failure. Images Figure 2 Figure 4 Figure 5 Figure 6 PMID:2399933

  5. A quick colorimetric method for total lipid quantification in microalgae.

    PubMed

    Byreddy, Avinesh R; Gupta, Adarsha; Barrow, Colin J; Puri, Munish

    2016-06-01

    Discovering microalgae with high lipid productivity are among the key milestones for achieving sustainable biodiesel production. Current methods of lipid quantification are time intensive and costly. A rapid colorimetric method based on sulfo-phospho-vanillin (SPV) reaction was developed for the quantification of microbial lipids to facilitate screening for lipid producing microalgae. This method was successfully tested on marine thraustochytrid strains and vegetable oils. The colorimetric method results correlated well with gravimetric method estimates. The new method was less time consuming than gravimetric analysis and is quantitative for lipid determination, even in the presence of carbohydrates, proteins and glycerol. PMID:27050419

  6. Modelling encapsulation of gold and silver nanoparticles inside lipid nanotubes

    NASA Astrophysics Data System (ADS)

    Baowan, Duangkamon; Thamwattana, Ngamta

    2014-02-01

    Lipid nanotubes are of particular interest for use as a template to create various one-dimensional nanostructures and as a carrier for drug and gene delivery. Understanding the encapsulation process is therefore crucial for such development. This paper models the interactions between lipid nanotubes and spheres of gold and silver nanoparticles and determines the critical dimension of lipid nanotubes that maximises the interaction with the nanoparticles. Our results confirm the acceptance of gold and silver nanoparticles inside lipid nanotubes. Further, we find that the lipid nanotube of radius approximately 10.23 nm is most favourable to encapsulate both types of nanoparticles.

  7. Model lipid bilayer with facile diffusion of lipids and integral membrane proteins.

    PubMed

    Wang, Tingting; Ingram, Colin; Weisshaar, James C

    2010-07-01

    A model membrane system is formed by the rupture of giant unilamellar vesicles (GUVs) onto a passivating layer comprising a PEG polymer cushion anchored in a lipid bilayer supported on glass. The novel use of pH-dependent electrostatic interactions between NeutrAvidin in the passivating layer and anionic lipids in the GUV drives vesicle rupture. The resulting "GUV pancakes" are single, planar lipid bilayer patches whose diameters vary from approximately 20 to 50 microm. The pancakes have several potential advantages for the in vitro study of protein-lipid interactions and integral membrane protein function. All components are commercially available. The pancakes resist nonspecific binding of vesicles containing protein. Both lipids and integral membrane proteins exhibit good lateral mobility in the GUV pancakes, as evidenced by single-particle tracking (SPT) of the DiD double-tailed fluorescent probe and of the integral membrane protein syntaxin-1A, labeled with AlexaFluor 633 (AF633-Syx). At least 80% of both probes exhibit free, homogeneous diffusion with a diffusion coefficient of approximately 5.5 microm(2) s(-1), which is more than 10 times faster than diffusion in a GUV pancake supported on bare glass. Atomic force microscopy (AFM) suggests that the polymer cushion has a height of approximately 4 nm. The mobility of a large fraction of the AF633-Syx probe suggests that even integral membrane proteins with large domains on both sides of the lipid bilayer should exhibit free diffusion within a GUV pancake. PMID:20459075

  8. Lipid order, saturation and surface property relationships: a study of human meibum saturation.

    PubMed

    Mudgil, Poonam; Borchman, Douglas; Yappert, Marta C; Duran, Diana; Cox, Gregory W; Smith, Ryan J; Bhola, Rahul; Dennis, Gary R; Whitehall, John S

    2013-11-01

    Tear film stability decreases with age however the cause(s) of the instability are speculative. Perhaps the more saturated meibum from infants may contribute to tear film stability. The meibum lipid phase transition temperature and lipid hydrocarbon chain order at physiological temperature (33 °C) decrease with increasing age. It is reasonable that stronger lipid-lipid interactions could stabilize the tear film since these interactions must be broken for tear break up to occur. In this study, meibum from a pool of adult donors was saturated catalytically. The influence of saturation on meibum hydrocarbon chain order was determined by infrared spectroscopy. Meibum is in an anhydrous state in the meibomian glands and on the surface of the eyelid. The influence of saturation on the surface properties of meibum was determined using Langmuir trough technology. Saturation of native human meibum did not change the minimum or maximum values of hydrocarbon chain order so at temperatures far above or below the phase transition of human meibum, saturation does not play a role in ordering or disordering the lipid hydrocarbon chains. Saturation did increase the phase transition temperature in human meibum by over 20 °C, a relatively high amount. Surface pressure-area studies showing the late take off and higher maximum surface pressure of saturated meibum compared to native meibum suggest that the saturated meibum film is quite molecularly ordered (stiff molecular arrangement) and elastic (molecules are able to rearrange during compression and expansion) compared with native meibum films which are more fluid agreeing with the infrared spectroscopic results of this study. In saturated meibum, the formation of compacted ordered islands of lipids above the surfactant layer would be expected to decrease the rate of evaporation compared to fluid and more loosely packed native meibum. Higher surface pressure observed with films of saturated meibum compared to native meibum

  9. Anti-inflammatory activity of cationic lipids.

    PubMed

    Filion, M C; Phillips, N C

    1997-10-01

    1. The effect of liposome phospholipid composition has been assumed to be relatively unimportant because of the presumed inert nature of phospholipids. 2. We have previously shown that cationic liposome formulations used for gene therapy inhibit, through their cationic component, the synthesis by activated macrophages of the pro-inflammatory mediators nitric oxide (NO) and tumour necrosis factor-alpha (TNF-alpha). 3. In this study, we have evaluated the ability of different cationic lipids to reduce footpad inflammation induced by carrageenan and by sheep red blood cell challenge. 4. Parenteral (i.p. or s.c) or local injection of the positively charged lipids dimethyldioctadecylammomium bromide (DDAB), dioleyoltrimethylammonium propane (DOTAP), dimyristoyltrimethylammonium propane (DMTAP) or dimethylaminoethanecarbamoyl cholesterol (DC-Chol) significantly reduced the inflammation observed in both models in a dose-dependent manner (maximum inhibition: 70-95%). 5. Cationic lipids associated with dioleyol- or dipalmitoyl-phosphatidylethanolamine retained their anti-inflammatory activity while cationic lipids associated with dipalmitoylphosphatidylcholine (DPPC) or dimyristoylphosphatidylglycerol (DMPG) showed no anti-inflammatory activity, indicating that the release of cationic lipids into the macrophage cytoplasm is a necessary step for anti-inflammatory activity. The anti-inflammatory activity of cationic lipids was abrogated by the addition of dipalmitoylphosphatidylethanolamine-poly(ethylene)glycol-2000 (DPPE-PEG2000) which blocks the interaction of cationic lipids with macrophages. 6. Because of the significant role of protein kinase C (PKC) in the inflammatory process we have determined whether the cationic lipids used in this study inhibit PKC activity. The cationic lipids significantly inhibited the activity of PKC but not the activity of a non-related protein kinase, PKA. The synthesis of interleukin-6 (IL-6), which is not dependent on PKC activity for its

  10. Microfluidic Platforms for on-chip Formulation and Small-Angle x-ray Analysis of the Phase Behavior of Lipid/Water Mixtures

    SciTech Connect

    Khvostichenko, Daria S.; Perry, Sarah L.; Kondrashkina, Elena; Guha, Sudipto; Brister, Keith; Kenis, Paul J.A.

    2012-03-27

    We present a microfluidic platform for on-chip formulation and X-ray analysis of lipidic mesophases formed upon mixing lipids and water. The platform is designed to study the effect of detergents on the phase behavior of lipid/water mixtures. The platform allows automated preparation of multiple samples of different composition from stock solutions and subsequent on-chip small-angle X-ray diffraction (SAXS) data collection. To ensure X-ray transparency of the platform we used thin layers of cyclic olefin copolymer (COC) and PDMS. The viability of the platform is demonstrated by mapping out a section of the phase diagram for lipid monoolein mixed with solutions of detergent {beta}-octylglucoside. The platform reported here is a viable alternative to the traditional method of establishing phase diagrams for lipid/solution mixtures. Compared to the conventional approach, a significantly smaller amount of sample is required for mapping phase diagrams of lipidic mesophases and samples of various compositions are prepared automatically. In ongoing work we are using these chips to rapidly determine the phase behavior of a range of lipids to establish their suitability for membrane protein crystallization, especially with respect to their sensitivity to detergent concentration.

  11. Determination of layer thickness and optical constants of thin films by using a modified pattern search method.

    PubMed

    Miloua, R; Kebbab, Z; Chiker, F; Sahraoui, K; Khadraoui, M; Benramdane, N

    2012-02-15

    We propose the use of a pattern search optimization technique in combination with a seed preprocessing procedure to determine the optical constants and thickness of thin films using only the transmittance spectra. The approach is quite flexible, straightforward to implement, and efficient in reaching the best fitting. We demonstrate the effectiveness of the method in extracting optical constants, even when the films are not displaying interference fringes. Comparison to a real-coded genetic algorithm shows that the modified pattern search is fast, almost accurate, and does not need any parameter adjustments. The approach is successfully applied to extract the thickness and optical constants of spray pyrolyzed nanocrystalline CdO thin films. PMID:22344069

  12. Correlation between the properties of the lipid matrix and the degrees of integrity and cohesion in healthy human Stratum corneum.

    PubMed

    Berthaud, Fabienne; Boncheva, Mila

    2011-03-01

    The correlation between the degrees of integrity and cohesion in healthy human Stratum corneum (SC) and the properties of the SC lipid matrix could be examined non-invasively in vivo using ATR-FTIR spectroscopy and measurements of pH, conductance, and transepidermal water loss (TEWL) taken in the course of tape-stripping. The change of TEWL following the removal of a SC layer with a predefined thickness served as a measure for the SC integrity, and the amount of protein removed by predefined number of tapes - as a measure for the SC cohesion. The extent of lipids organized in orthorhombic lattices and the pH in the inner SC emerged as the main factors that determine the degree of integrity. The amounts and molecular organization of the SC lipids did not correlate with the degree of cohesion, while the pH and the hydration of SC correlated well with the degree of cohesion in the superficial but not in the inner SC layers. This study evidenced the variability of SC integrity and cohesion existing in healthy human skin, demonstrated the importance of the lipid molecular organization for the SC integrity, and illustrated the limitations in the determination the degree of corneodesmolysis in SC based only on the protein content of tape-strips. PMID:21054560

  13. Use of combined chromatographic methods including thin-layer chromatography for analysis of complex polymer systems. Determination of the polydispersity of block copolymers of styrene and methyl methacrylate by gel permeation, thin-layer and pyrolysis gas chromatography.

    PubMed

    Belenkii, B G; Gankina, E S; Nefedov, P P; Lazareva, M A; Savitskaya, T S; Volchikhina, M D

    1975-05-01

    A combination of gel permeation chromatography (GPC), thin-layer chromatography (TLC) and pyrolysis gas chromatography (PGC) has been used for investigations of a polymethyl methacrylate-polystyrene-polymethyl methacrylate block copolymer. Continuous distribution of the polymer (40-mg sample) was attained according to the content of the styrene and methyl methacrylate units and of the block copolymer and according to the composition of the copolymer as functions of the hydrodynamic radius of the macromolecules. The polymer was subjected to a preliminary fractionation with an analytical gel chromatograph. The fractions were investigated by TLC, which permitted the separation of the block copolymer and the homopolymers. The composition of the fractions obtained by GPC and TLC was determined by PGC. As a result, it was possible to establish the composition of the block copolymer and its ratio to polymethyl methacrylate in each fraction. This investigation was based on a combination of highly effective fractionation by chromatographic methods with precise quantitative ratios obtained from Benoit's universal calibration graph and from determinations of the composition of the polymer fractions by PGC. The mechanism of the TLC of polymers, including the appearance of artefacts that distort the results of analysis, is also discussed. PMID:1150816

  14. Lipid Droplets And Cellular Lipid Metabolism

    PubMed Central

    Walther, Tobias C.; Farese, Robert V.

    2013-01-01

    Among organelles, lipid droplets (LDs) uniquely constitute a hydrophobic phase in the aqueous environment of the cytosol. Their hydrophobic core of neutral lipids stores metabolic energy and membrane components, making LDs hubs for lipid metabolism. In addition, LDs are implicated in a number of other cellular functions, ranging from protein storage and degradation to viral replication. These processes are functionally linked to many physiological and pathological conditions, including obesity and related metabolic diseases. Despite their important functions and nearly ubiquitous presence in cells, many aspects of LD biology are unknown. In the past few years, the pace of LD investigation has increased, providing new insights. Here, we review the current knowledge of LD cell biology and its translation to physiology. PMID:22524315

  15. A new estimation of the total flavonoids in silkworm cocoon sericin layer through aglycone determination by hydrolysis-assisted extraction and HPLC-DAD analysis

    PubMed Central

    Zhao, Jin-Ge; Zhang, Yu-Qing

    2016-01-01

    Background Silk sericin and a few non-protein components isolated from the cocoon layer including two silk proteins in silkworm Bombyx mori has many bioactivities. The dietary sericin possess antinatural oxidation, anticancer, antihyperlipidemic, and antidiabetic activities. The non-protein components surrounding the sericin layer involve in wax, pigments mainly meaning flavonoids, sugars, and other impurities. However, very few investigations have reported the estimation of the total flavonoids derived from the cocoon layer. The flavonoids are commonly present in their glycosylated forms and mostly exist as quercetin glycosides in the sericin layers of silkworm cocoons. Objective The aim of this study was to find a more accurate method to estimate the level of the total flavonoids in silkworm cocoons. Design An efficient procedure of hydrolysis-assisted extraction (HAE) was first established to estimate the level of the total flavonoids through the determination of their aglycones, quercetin, and kaempferol. Then, a comparison was made between traditional colorimetric method and our method. In addition, the antioxidant activities of hydrolysis-assisted extract sample were determined. Results The average contents of quercetin and kaempferol were 1.98 and 0.42 mg/g in Daizo cocoon. Their recoveries were 99.56 and 99.17%. The total sum of quercetin and kaempferol was detected to be 2.40±0.07 mg/g by HAE-HPLC, while the total flavonoids (2.59±0.48 mg/g) estimated by the traditional colorimetric method were only equivalent to 1.28±0.04 mg/g of quercetin. The HAE sample also exhibits that IC50 values of scavenging ability of diphenyl picryl hydrazinyl (DPPH) radical and hydroxyl radical (HO·) are 243.63 µg/mL and 4.89 mg/mL, respectively. Conclusions These results show that the HAE-HPLC method is specificity of cocoon and far superior to the colorimetric method. Therefore, this study has profound significance for the comprehensive utilization of silkworm cocoon and

  16. Simultaneous determination of triamcinolone acetonide palmitate and triamcinolone acetonide in beagle dog plasma by UPLC-MS/MS and its application to a long-term pharmacokinetic study of triamcinolone acetonide palmitate lipid emulsion injection.

    PubMed

    Liu, Hui; Yang, Mingjing; Wu, Panpan; Guan, Jiao; Men, Lei; Lin, Hongli; Tang, Xing; Zhao, Yunli; Yu, Zhiguo

    2015-02-01

    In order to investigate the pharmacokinetics of triamcinolone acetonide palmitate (TAP) which is a lipid-soluble prodrug of triamcinolone acetonide (TA), a rapid, simple, sensitive and reproducible UPLC-MS/MS method has been developed and validated for the simultaneous determination of TAP and TA in beagle dog plasma. After simple liquid-liquid extraction, the analytes and internal standard (dexamethasone, DEX) were separated on Phenomenex Luna C18 column (50 mm × 2.1mm, 1.7 μm) using a mobile phase consisting of solvent A (acetonitrile) and solvent B (0.1% ammonia solution) at a flow rate of 0.2 ml/min with gradient elution. Acquisition of mass spectrometric data was performed in multiple reaction monitoring (MRM) mode via positive electrospray ionization using the ion transitions of m/z 673.5→397.3, 435.3→415.3 and 393.3→355.3 for TAP, TA and IS, respectively. The method was of satisfactory specificity, sensitivity, precision and accuracy over the concentration range of 1-1,000 ng/ml for TAP and 0.5-500 ng/ml for TA. The intra- and inter-day precisions for both TAP and TA were 3.2% to 18.7% and the accuracy was in the range of -8.4% to 6.8%. The mean recoveries of TAP, TA and IS were 86.7-104.7%. The method was successfully applied to a long-term pharmacokinetic study of TAP and TA after 28-day repeated intravenous administration of TAP lipid emulsion injection to beagle dogs. PMID:25497892

  17. Lipid exchange between membranes.

    PubMed Central

    Jähnig, F

    1984-01-01

    The exchange of lipid molecules between vesicle bilayers in water and a monolayer forming at the water surface was investigated theoretically within the framework of thermodynamics. The total number of exchanged molecules was found to depend on the bilayer curvature as expressed by the vesicle radius and on the boundary condition for exchange, i.e., whether during exchange the radius or the packing density of the vesicles remains constant. The boundary condition is determined by the rate of flip-flop within the bilayer relative to the rate of exchange between bi- and monolayer. If flip-flop is fast, exchange is independent of the vesicle radius; if flip-flop is slow, exchange increases with the vesicle radius. Available experimental results agree with the detailed form of this dependence. When the theory was extended to exchange between two bilayers of different curvature, the direction of exchange was also determined by the curvatures and the boundary conditions for exchange. Due to the dependence of the boundary conditions on flip-flop and, consequently, on membrane fluidity, exchange between membranes may partially be regulated by membrane fluidity. PMID:6518251

  18. Determination of water-soluble hexavalent chromium in clinker samples by wavelength-dispersive X-ray fluorescence spectrometry after concentration in activated layers.

    PubMed

    Marguí, Eva; Fontàs, Claudia; Toribio, Marta; Guillem, Manel; Hidalgo, Manuela; Queralt, Ignacio

    2010-05-01

    The determination of hexavalent chromium (Cr(VI)) in cement-related material extracts is frequently monitored in cement industries to comply with the European Directive (2003/53/EC) that limits the use of cements containing more than 2 mg kg(-1) of water-soluble Cr(VI). In the present work, a rapid and simple method for the determination of water-soluble Cr(VI) in clinker samples has been developed. The analytical methodology is based on the combined use of a low cost Cr(VI) isolation procedure using activated layers followed by their analysis using wavelength-dispersive X-ray fluorescence (WDXRF) spectrometry. WDXRF instrumentation is a common tool used for determining the chemical composition of all materials involved in cement production and also for the quality control of the products produced in cement and concrete factories. Therefore, the presented methodology does not imply the use of additional instrumentation in cement-industries laboratories and can be used as a comparative method to the spectrophotometric reference (EN 196-10:2006). The analytical parameters evaluated (selectivity, limit of detection, linearity, and precision) prove to be suitable for the intended purpose, and the methodology has successfully been applied to determine water-soluble Cr(VI) in several clinker samples. PMID:20482975

  19. Validation of a thin-layer chromatography for the determination of hydrocortisone acetate and lidocaine in a pharmaceutical preparation.

    PubMed

    Dołowy, Małgorzata; Kulpińska-Kucia, Katarzyna; Pyka, Alina

    2014-01-01

    A new specific, precise, accurate, and robust TLC-densitometry has been developed for the simultaneous determination of hydrocortisone acetate and lidocaine hydrochloride in combined pharmaceutical formulation. The chromatographic analysis was carried out using a mobile phase consisting of chloroform+acetone+ammonia (25%) in volume composition 8:2:0.1 and silica gel 60F254 plates. Densitometric detection was performed in UV at wavelengths 200 nm and 250 nm, respectively, for lidocaine hydrochloride and hydrocortisone acetate. The validation of the proposed method was performed in terms of specificity, linearity, limit of detection (LOD), limit of quantification (LOQ), precision, accuracy, and robustness. The applied TLC procedure is linear in hydrocortisone acetate concentration range of 3.75÷12.50  μg·spot(-1), and from 1.00÷2.50  μg·spot(-1) for lidocaine hydrochloride. The developed method was found to be accurate (the value of the coefficient of variation CV [%] is less than 3%), precise (CV [%] is less than 2%), specific, and robust. LOQ of hydrocortisone acetate is 0.198  μg·spot(-1) and LOD is 0.066  μg·spot(-1). LOQ and LOD values for lidocaine hydrochloride are 0.270 and 0.090  μg·spot(-1), respectively. The assay value of both bioactive substances is consistent with the limits recommended by Pharmacopoeia. PMID:24526880

  20. Validation of a Thin-Layer Chromatography for the Determination of Hydrocortisone Acetate and Lidocaine in a Pharmaceutical Preparation

    PubMed Central

    Dołowy, Małgorzata; Kulpińska-Kucia, Katarzyna; Pyka, Alina

    2014-01-01

    A new specific, precise, accurate, and robust TLC-densitometry has been developed for the simultaneous determination of hydrocortisone acetate and lidocaine hydrochloride in combined pharmaceutical formulation. The chromatographic analysis was carried out using a mobile phase consisting of chloroform + acetone + ammonia (25%) in volume composition 8 : 2 : 0.1 and silica gel 60F254 plates. Densitometric detection was performed in UV at wavelengths 200 nm and 250 nm, respectively, for lidocaine hydrochloride and hydrocortisone acetate. The validation of the proposed method was performed in terms of specificity, linearity, limit of detection (LOD), limit of quantification (LOQ), precision, accuracy, and robustness. The applied TLC procedure is linear in hydrocortisone acetate concentration range of 3.75 ÷ 12.50 μg·spot−1, and from 1.00 ÷ 2.50 μg·spot−1 for lidocaine hydrochloride. The developed method was found to be accurate (the value of the coefficient of variation CV [%] is less than 3%), precise (CV [%] is less than 2%), specific, and robust. LOQ of hydrocortisone acetate is 0.198 μg·spot−1 and LOD is 0.066 μg·spot−1. LOQ and LOD values for lidocaine hydrochloride are 0.270 and 0.090 μg·spot−1, respectively. The assay value of both bioactive substances is consistent with the limits recommended by Pharmacopoeia. PMID:24526880

  1. Ex-situ gas diffusion layer intrusion effect determination of polymer electrolyte membrane fuel cell flow fields

    NASA Astrophysics Data System (ADS)

    Haase, S.; Rauber, M.

    2015-09-01

    In automotive PEM fuel cell systems, one of the most important targets is to reduce the parasitic power of balance of plant components, e.g. the air supply. This can be achieved for example by decreasing air stoichiometry. However, this could lead to bad flow sharing in the fuel cell stack. Therefore the fluid distribution in the flow field has to be evaluated, understood and optimized. This work evaluates the effect of GDL intrusion on the pressure drop via ex-situ determination of GDL intrusion using CFD simulation. The intruded GDL geometries, evaluated by an optical microscope with 200 times enlargement, are transferred to pressure drop behaviors by a numerical CFD model. These results are compared to the results of the differential pressure method of mapping the pressure distribution, described in [43]. The intrusion of the GDL leads to homogeneous flow distribution up to clamping pressures of 2.5 MPa. The inhomogeneous intrusion, induced by cracked fibers that extend into the channel, dominates the flow at higher clamping pressures and leads to the exponential increase in pressure drop in the differential pressure method. For clamping pressures used in typical fuel cell applications, the results of both methods show homogeneous flow through the channels.

  2. Lipids: Absorption and transport

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Lipid has long been recognized as an important dietary component. Dietary lipid (fat) is a critical source of metabolic energy and a substrate for the synthesis of metabolically active compounds (essential fatty acids), and serves as a carrier for other nutrients such as the fat-soluble vitamins A, ...

  3. Lysosomal Lipid Storage Diseases

    PubMed Central

    Schulze, Heike; Sandhoff, Konrad

    2011-01-01

    Lysosomal lipid storage diseases, or lipidoses, are inherited metabolic disorders in which typically lipids accumulate in cells and tissues. Complex lipids, such as glycosphingolipids, are constitutively degraded within the endolysosomal system by soluble hydrolytic enzymes with the help of lipid binding proteins in a sequential manner. Because of a functionally impaired hydrolase or auxiliary protein, their lipid substrates cannot be degraded, accumulate in the lysosome, and slowly spread to other intracellular membranes. In Niemann-Pick type C disease, cholesterol transport is impaired and unesterified cholesterol accumulates in the late endosome. In most lysosomal lipid storage diseases, the accumulation of one or few lipids leads to the coprecipitation of other hydrophobic substances in the endolysosomal system, such as lipids and proteins, causing a “traffic jam.” This can impair lysosomal function, such as delivery of nutrients through the endolysosomal system, leading to a state of cellular starvation. Therapeutic approaches are currently restricted to mild forms of diseases with significant residual catabolic activities and without brain involvement. PMID:21502308

  4. Free Lipid A Isolated from Porphyromonas gingivalis Lipopolysaccharide Is Contaminated with Phosphorylated Dihydroceramide Lipids: Recovery in Diseased Dental Samples

    PubMed Central

    Bajrami, Bekim; Clark, Robert B.; Housley, William; Yao, Xudong

    2012-01-01

    Recent reports indicate that Porphyromonas gingivalis mediates alveolar bone loss or osteoclast modulation through engagement of Toll-like receptor 2 (TLR2), though the factors responsible for TLR2 engagement have yet to be determined. Lipopolysaccharide (LPS) and lipid A, lipoprotein, fimbriae, and phosphorylated dihydroceramides of P. gingivalis have been reported to activate host cell responses through engagement of TLR2. LPS and lipid A are the most controversial in this regard because conflicting evidence has been reported concerning the capacity of P. gingivalis LPS or lipid A to engage TLR2 versus TLR4. In the present study, we first prepared P. gingivalis LPS by the Tri-Reagent method and evaluated this isolate for contamination with phosphorylated dihydroceramide lipids. Next, the lipid A prepared from this LPS was evaluated for the presence of phosphorylated dihydroceramide lipids. Finally, we characterized the lipid A by the matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) and electrospray-MS methods in order to quantify recovery of lipid A in lipid extracts from diseased teeth or subgingival plaque samples. Our results demonstrate that both the LPS and lipid A derived from P. gingivalis are contaminated with phosphorylated dihydroceramide lipids. Furthermore, the lipid extracts derived from diseased teeth or subgingival plaque do not contain free lipid A constituents of P. gingivalis but contain substantial amounts of phosphorylated dihydroceramide lipids. Therefore, the free lipid A of P. gingivalis is not present in measurable levels at periodontal disease sites. Our results also suggest that the TLR2 activation of host tissues attributed to LPS and lipid A of P. gingivalis could actually be mediated by phosphorylated dihydroceramides. PMID:22144487

  5. Lipids of Archaeal Viruses

    PubMed Central

    Roine, Elina; Bamford, Dennis H.

    2012-01-01

    Archaeal viruses represent one of the least known territory of the viral universe and even less is known about their lipids. Based on the current knowledge, however, it seems that, as in other viruses, archaeal viral lipids are mostly incorporated into membranes that reside either as outer envelopes or membranes inside an icosahedral capsid. Mechanisms for the membrane acquisition seem to be similar to those of viruses infecting other host organisms. There are indications that also some proteins of archaeal viruses are lipid modified. Further studies on the characterization of lipids in archaeal viruses as well as on their role in virion assembly and infectivity require not only highly purified viral material but also, for example, constant evaluation of the adaptability of emerging technologies for their analysis. Biological membranes contain proteins and membranes of archaeal viruses are not an exception. Archaeal viruses as relatively simple systems can be used as excellent tools for studying the lipid protein interactions in archaeal membranes. PMID:23049284

  6. Skin surface lipids of the domestic chicken, and neutral lipid standards as stimuli for the penetration response of Austrobilharzia variglandis cercariae.

    PubMed

    Zibulewsky, J; Fried, B; Bacha, W J

    1982-10-01

    Lipids were extracted from the skin of 2-wk-old domestic chickens using sterile cotton gauze dampened with chloroform:methanol (2:1). Preparative thin-layer chromatography separated the skin lipids into six major fractions: phospholipids, free sterols, free fatty acids, triglycerides, methyl esters, sterol esters. The penetration response of the marine avian schistosome cercaria, Austrobilharzia variglandis, to chicken skin lipid fractions, and to neutral lipid standards, was tested by coating lipids on agar in a Petri dish containing a seawater overlay. All neutral lipids tested produced significantly greater penetration responses than the chloroform control. The phospholipid skin fraction killed cercariae. Lipid from whole chicken skin produced the greatest penetration response, followed by free fatty acids and free sterol skin fractions. Of the standards tested, the whole neutral lipid standard, containing cholesterol, oleic acid, triolein, methyl oleate, and cholesteryl oleate, produced the greatest response, followed by the cholesterol standard and the oleic acid standard. PMID:7131196

  7. Dissolvable layered double hydroxide coated magnetic nanoparticles for extraction followed by high performance liquid chromatography for the determination of phenolic acids in fruit juices.

    PubMed

    Saraji, Mohammad; Ghani, Milad

    2014-10-31

    A magnesium-aluminum layered double hydroxide coated on magnetic nanoparticles was synthesized and used as a sorbent to extract some phenolic acids including p-hydroxy benzoic acid, caffeic acid, syringic acid, p-coumaric acid and ferulic acid from fruit juices. After extraction, the elution step was performed through dissolving double hydroxide layers containing the analytes by changing the solution pH. The extracted phenolic acids were separated and quantified using high performance liquid chromatography-photodiode array detection. Experimental parameters such as sorbent amount, solution pH, desorption solvent volume and extraction time were studied and optimized. The linearity range of the method was between 2 and 500μgL(-1) with the determination coefficient (r(2)) higher than 0.991. Relative standard deviations for intra- and inter-day precision for the analytes at 100μgL(-1) were in the range of 4.3-9.2% and 4.9-8.6%, respectively. Batch-to-batch reproducibility at 100μgL(-1) concentration level was in the range of 7.8-11% (n=3). The limits of detection were between 0.44 and 1.3μgL(-1). Relative recoveries higher than 81% with RSDs in the range of 4.2-9.7% were obtained in the analysis of fruit juice samples. PMID:25260344

  8. Determination of the thermal diffusivity of bulk and layered samples by time domain thermoreflectance: Interest of lateral heat diffusion investigation in nanoscale time range

    SciTech Connect

    Belliard, L. Charron, E.; Vincent, S.; Perrin, B.; Fournier, D.; Frétigny, C.

    2015-02-14

    We report on thermal investigations performed in a time resolved experimental scheme. The time domain thermoreflectance (TDTR) is applied in an unusual geometry where the pump and probe beams are not superimposed but focused and shifted. In this way, the determination of the in-plane thermal diffusivity is achieved from temperature snapshots at different time delays. In the first part, taking into account the specific generation process and the detection inherent to the time domain thermoreflectance approach, an analytical solution for the temperature field is obtained for bulk samples, and compared to experimental data. A comparison with the frequency domain thermoreflectance microscopy is also outlined. In Part II section, the lateral heat diffusion in a layered structure is investigated. The comparison of the heat diffusion spreading in case of a highly conductive layer deposited on an insulator substrate and the reverse situation are carefully studied. Finally, we show how the time dependence is efficient to probe and identify material thermal properties or thermal interfacial resistance.

  9. Determination of Marginal Conditions for Thermoacoustic Oscillations in a Looped Tube by Evolution of an Initial Disturbance Based on the Boundary-Layer Theory

    NASA Astrophysics Data System (ADS)

    Shimizu, Dai; Sugimoto, Nobumasa

    2014-03-01

    Marginal conditions are determined for the onset of thermoacoustic oscillations of a gas in a looped tube with a so-called stack sandwiched by hot and cold heat exchangers on the basis of the boundary-layer theory so far developed. Given a couple of impulses applied initially to a quiescent gas, the evolution of an infinitesimally small disturbance is studied by solving an initial-value problem to the linearized equations. Marginal states correspond to those in which the initial disturbance neither decays nor grows with time. In the case studied by Ueda and Kato [J. Acoust. Soc. Am. 124, 851 (2008)], the marginal conditions are obtained in two cases of the temperature distribution in the thermal buffer tube and compared with their results. To identify the marginal curves, the porosity of the stack or one of the subsidiary parameters such as the wall thickness of the stack is required in addition to the squared ratio of the hydraulic radius to the typical thickness of the thermal diffusion layer in a flow passage of gas. It is found that the marginal conditions are in qualitative agreement with the experimental results and that the right branch of the marginal curve is obtainable down to such a considerably low temperature ratio that the theory may become invalid.

  10. Direct determination of the stacking order in Gd{sub 2}O{sub 3} epi-layers on GaAs.

    SciTech Connect

    Yacoby, Y.; Sowwan, M.; Pindak, R.; Cross, J.; Walko, D.; Stern, E.; Pitney, J.; MacHarrie, R.; Hong, M.; Clarke, R.; Experimental Facilities Division; Hebrew Univ.; BNL; Univ. of Washington; Bell Lab Agere Stystems; Univ. of Michigan

    2003-01-01

    We have used Coherent Bragg Rod Analysis (COBRA) to investigate the atomic structure of a 5.6 nm thick Gd{sub 2}O{sub 3} film epitaxially grown on a (100) GaAs substrate. COBRA is a method to directly obtain the structure of systems periodic in two-dimensions by determining the complex scattering factors along the substrate Bragg rods. The system electron density and atomic structure are obtained by Fourier transforming the complex scattering factors into real space. The results show that the stacking order of the first seven Gd{sub 2}O{sub 3} film layers resembles the stacking order of Ga and As layers in GaAs then changes to the stacking order of cubic bulk Gd{sub 2}O{sub 3}. This behavior is distinctly different from the measured stacking order in a 2.7 nm thick Gd{sub 2}O{sub 3} in which the GaAs stacking order persists throughout the entire film.

  11. Structural studies of aliphatic substituted phthalocyanine-lipid multilayers.

    PubMed

    Zarbakhsh, Ali; Campana, Mario; Mills, David; Webster, John R P

    2010-10-01

    A Langmuir-Blodgett film of aliphatic substituted phthalocyanines on a C18 silane supporting layer coupled onto a silicon substrate has been investigated using neutron reflectometry. This multilayer structure is seen as a possible candidate for phthalocyanine-lipid biosensor devices. The results show the suitability of the C18 ligands as an anchoring layer for the phthalocyanines. The scattering length density profiles demonstrate the effectiveness of a lipid monolayer in partitioning the composition of phthalocyanine layers from that of the bulk liquid. The effectiveness of this barrier is a critical factor in the efficiency of such devices. PMID:20831252

  12. Coupled Diffusion in Lipid Bilayers upon Close Approach

    PubMed Central

    2015-01-01

    Biomembrane interfaces create regions of slowed water dynamics in their vicinity. When two lipid bilayers come together, this effect is further accentuated, and the associated slowdown can affect the dynamics of larger-scale processes such as membrane fusion. We have used molecular dynamics simulations to examine how lipid and water dynamics are affected as two lipid bilayers approach each other. These two interacting fluid systems, lipid and water, both slow and become coupled when the lipid membranes are separated by a thin water layer. We show in particular that the water dynamics become glassy, and diffusion of lipids in the apposed leaflets becomes coupled across the water layer, while the “outer” leaflets remain unaffected. This dynamic coupling between bilayers appears mediated by lipid–water–lipid hydrogen bonding, as it occurs at bilayer separations where water–lipid hydrogen bonds become more common than water–water hydrogen bonds. We further show that such coupling occurs in simulations of vesicle–vesicle fusion prior to the fusion event itself. Such altered dynamics at membrane–membrane interfaces may both stabilize the interfacial contact and slow fusion stalk formation within the interface region. PMID:25535654

  13. Lipochemistry of the progamic stage of a self-incompatible species: Neutral lipids and fatty acids of the secretory stigma during its glandular activity, and of the solid style, the ovary and the anther in Forsythia intermedia Zab. (Heterostylic species).

    PubMed

    Dumas, C

    1977-01-01

    Chromatographic (thin-layer, gas column, column chromatography) analyses of neutral lipids and fatty acids of reproductive tissues of Forsythia intermedia Zab., a self-incompatible species, were performed with two objectives in mind: 1. To determine whether there is a qualitative evolution of the different classes of lipids and fatty acids that could be correlated with the three functional stages observed during previous histochemical and ultrastructural studies. The stigmatic exudate and intracellular accumulations consist mainly of neutral lipids. 2. To compare the lipid composition of the stigma (both "thrum" and "pin" forms) with that of the style, the ovary, and the anther, and to investigate the possible existence of a stigma-specific lipid compound. Stigmatic neutral lipids are found mostly in a glyceridic mixture probably containing hydrocarbons and terpenes. The fatty acids identified are between C:7 and C: 12, with the maximum unsaturated form being a C: 18. During the secretory process there is no great qualitative diference between the neutral lipids and fatty acids found in the stigmas of "thrum" and "pin" forms. Sterols are present in styles, ovaries, and anthers, but not in stigmas. They represent the only difference in the lipid composition of these various floral structures. PMID:24420636

  14. Avanti lipid tools: connecting lipids, technology, and cell biology.

    PubMed

    Sims, Kacee H; Tytler, Ewan M; Tipton, John; Hill, Kasey L; Burgess, Stephen W; Shaw, Walter A

    2014-08-01

    Lipid research is challenging owing to the complexity and diversity of the lipidome. Here we review a set of experimental tools developed for the seasoned lipid researcher, as well as, those who are new to the field of lipid research. Novel tools for probing protein-lipid interactions, applications for lipid binding antibodies, enhanced systems for the cellular delivery of lipids, improved visualization of lipid membranes using gold-labeled lipids, and advances in mass spectrometric analysis techniques will be discussed. Because lipid mediators are known to participate in a host of signal transduction and trafficking pathways within the cell, a comprehensive lipid toolbox that aids the science of lipidomics research is essential to better understand the molecular mechanisms of interactions between cellular components. This article is part of a Special Issue entitled Tools to study lipid functions. PMID:24954118

  15. Use of fluorescence-activated flow cytometry to determine membrane lipid peroxidation during hypothermic liquid storage and freeze-thawing of viable boar sperm loaded with C11-BODIPY 581/591

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Part of the reduction in boar sperm motility and fertility associated with hypothermic liquid storage and cryopreservation may be due to membrane lipid peroxidation. Lipid peroxidation was monitored by the change in fluorescence emission of the lipophilic probe 4, 4-Difluoro-5-(4-phenyl-1,3-butadien...

  16. Incorporation of liquid lipid in lipid nanoparticles for ocular drug delivery enhancement

    NASA Astrophysics Data System (ADS)

    Shen, Jie; Sun, Minjie; Ping, Qineng; Ying, Zhi; Liu, Wen

    2010-01-01

    The present work investigates the effect of liquid lipid incorporation on the physicochemical properties and ocular drug delivery enhancement of nanostructured lipid carriers (NLCs) and attempts to elucidate in vitro and in vivo the potential of NLCs for ocular drug delivery. The CyA-loaded or fluorescein-marked nanocarriers composed of Precifac ATO 5 and Miglyol 840 (as liquid lipid) were prepared by melting-emulsion technology, and the physicochemical properties of nanocarriers were determined. The uptake of nanocarriers by human corneal epithelia cell lines (SDHCEC) and rabbit cornea was examined. Ex vivo fluorescence imaging was used to investigate the ocular distribution of nanocarriers. The in vitro cytotoxicity and in vivo acute tolerance were evaluated. The higher drug loading capacity and improved in vitro sustained drug release behavior of lipid nanoparticles was found with the incorporation of liquid lipid in lipid nanoparticles. The uptake of nanocarriers by the SDHCEC was increased with the increase in liquid lipid loading. The ex vivo fluorescence imaging of the ocular tissues indicated that the liquid lipid incorporation could improve the ocular retention and penetration of ocular therapeutics. No alternation was macroscopically observed in vivo after ocular surface exposure to nanocarriers. These results indicated that NLC was a biocompatible and potential nanocarrier for ocular drug delivery enhancement.

  17. Lipid-absorbing Polymers

    NASA Technical Reports Server (NTRS)

    Marsh, H. E., Jr.; Wallace, C. J.

    1973-01-01

    The removal of bile acids and cholesterol by polymeric absorption is discussed in terms of micelle-polymer interaction. The results obtained with a polymer composed of 75 parts PEO and 25 parts PB plus curing ingredients show an absorption of 305 to 309%, based on original polymer weight. Particle size effects on absorption rate are analyzed. It is concluded that crosslinked polyethylene oxide polymers will absorb water, crosslinked polybutadiene polymers will absorb lipids; neither polymer will absorb appreciable amounts of lipids from micellar solutions of lipids in water.

  18. Determination of organophosphate flame retardants and plasticizers in lipid-rich matrices using dispersive solid-phase extraction as a sample cleanup step and ultra-high performance liquid chromatography with atmospheric pressure chemical ionization mass spectrometry.

    PubMed

    Chu, Shaogang; Letcher, Robert J

    2015-07-23

    A fast, robust and highly sensitive analysis method for determination of trace levels of organophosphate ester (OPE) flame retardants and plasticizers in lipid-rich samples was presently developed, and based on ultra-high performance liquid chromatography-tandem mass spectrometry coupled to a positive atmospheric pressure chemical ionization source (UHPLC-MS/MS-APCI(+)). The target OPEs in the sample were extracted from the biota samples, such as egg and liver, by ultrasonic extraction, and cleaned up further by dispersive solid phase extraction (d-ESP). As a result, background contamination was largely reduced. Different dispersive ESP sorbents were tested and primary secondary amine (PSA) bonded silica sorbents showed the best recoveries for these target OPEs. The recoveries obtained were in the range 54-113% (RSD<17%), with method limits of quantification (MLOQs) ranging between 0.06 and 0.29ng/g in egg, and 0.05 and 0.50ng/g w.w. in liver sample. The matrix effects (MEs) associated with using APCI(+) and ESI(+) sources were investigated. APCI(+) showed much less ion suppression than ESI(+) for the determination of these OPEs. For egg and liver samples, the APCI(+) ME values ranged from 40% to 94%, while ESI(+) ME values ranged from 0% to 36%. Although APCI(+) was used for the determination of OPEs, the ionization mechanism might mainly be a thermospray ionization process. This UHPLC-MS/MS-APCI(+) method showed good response linearity for calibration (R2>0.99). The proposed method was applied to real environmental bird egg and fish samples, where several OPE were quantifiable and different OPE patterns was observed between samples. PMID:26231904

  19. Comparing the content of lipids derived from the eye lenses of various species.

    PubMed

    Panz, Tomasz; Lepiarczyk, Magdalena; Zuber, Agnieszka

    2011-01-01

    The lipid content in the eye lens was analyzed and compared among various species in this study. The eye lens lipids of the following species were investigated: cow, horse, duck, and freshwater trout. Additionally, the lipids derived from cataractous bovine lens and from cataractous human eye lens lipoprotein complexes were analyzed. The following lipid classes were detected in clear lenses: cholesterol, sphingomyelin, phosphatidylcholine, phosphatidyletanolamine, and phosphatidylserine. In cataractous bovine lens and in lipoprotein complexes from human nuclear cataract, phosphatidyloinositol and phosphatidyloglycerol were detected. Cholesterol and sphingomyelin, essential for hypothetical formation of cholesterol-rich domains, were the most abundant lipids in the lenses of all investigated species. These two components of eye lens lipid fraction were analyzed quantitatively using thin layer chromatography and spectrophotometric assay; the other lipids were identified qualitatively using thin layer chromatography. PMID:22038221

  20. Hydration in Lipid Monolayers: Correlation of Water Activity and Surface Pressure.

    PubMed

    Disalvo, E Anibal; Hollmann, Axel; Martini, M Florencia

    2015-01-01

    In order to give a physical meaning to each region of the membrane we define the interphase as the region in a lipid membrane corresponding to the polar head groups imbibed in water with net different properties than the hydrocarbon region and the water phase. The interphase region is analyzed under the scope of thermodynamics of surface and solutions based on the definition of Defay-Prigogine of an interphase and the derivation that it has in the understanding of membrane processeses in the context of biological response. In the view of this approach, the complete monolayer is considered as the lipid layer one molecule thick plus the bidimensional solution of the polar head groups inherent to it (the interphase region). Surface water activity appears as a common factor for the interaction of several aqueous soluble and surface active proteins with lipid membranes of different composition. Protein perturbation can be measured by changes in the surface pressure of lipid monolayers at different initial water surface activities. As predicted by solution chemistry, the increase of surface pressure is independent of the particle nature that dissolves. Therefore, membranes give a similar response in terms of the determined surface states given by water activity independent of the protein or peptide. PMID:26438267

  1. Proto-Organism Kinetics: Evolutionary Dynamics of Lipid Aggregates with Genes and Metabolism

    NASA Astrophysics Data System (ADS)

    Rasmussen, Steen; Chen, Liaohai; Stadler, Bärbel M. R.; Stadler, Peter F.

    2004-02-01

    A synthetic proto-organism could be self-assembled by integrating a lipid proto-container with a proto-metabolic subsystem and a proto-genetic subsystem. This three-component system can use energy and nutrients by means of either redox or photo-chemical reactions, evolve its proto-genome by means of template directed replication, and ultimately die. The evolutionary dynamics of the proto-organism depends crucially on the chemical kinetics of its sub-systems and on their interplay. In this work the template replication kinetics is investigated and it is found that the product inhibition inherent in the ligation-like replication process allows for coexistence of unrelated self-replicating proto-genes in the lipid surface layer. The combined catalytic effects from the proto-genes on the metabolic production rates determine the fate of the strain protocell.

  2. Resveratrol-loaded solid lipid nanoparticles versus nanostructured lipid carriers: evaluation of antioxidant potential for dermal applications

    PubMed Central

    Gokce, Evren H; Korkmaz, Emrah; Dellera, Eleonora; Sandri, Giuseppina; Bonferoni, M Cristina; Ozer, Ozgen

    2012-01-01

    Background Excessive generation of radical oxygen species (ROS) is a contributor to skin pathologies. Resveratrol (RSV) is a potent antioxidant. Solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) can ensure close contact and increase the amount of drug absorbed into the skin. In this study, RSV was loaded into SLN and NLC for dermal applications. Methods Nanoparticles were prepared by high shear homogenization using Compritol 888ATO, Myglyol, Poloxamer188, and Tween80. Particle size (PS), polydispersity index (PI), zeta potential (ZP), drug entrapment efficiency (EE), and production yield were determined. Differential scanning calorimetry (DSC) analysis and morphological transmission electron microscopy (TEM) examination were conducted. RSV concentration was optimized with cytotoxicity studies, and net intracellular accumulation of ROS was monitored with cytofluorimetry. The amount of RSV was determined from different layers of rat abdominal skin. Results PS of uniform RSV-SLN and RSV-NLC were determined as 287.2 nm ± 5.1 and 110.5 nm ± 1.3, respectively. ZP was −15.3 mV ± 0.4 and −13.8 mV ± 0.1 in the same order. The drug EE was 18% higher in NLC systems. TEM studies showed that the drug in the shell model was relevant for SLN, and that the melting point of the lipid in NLC was slightly lower. Concentrations below 50 μM were determined as suitable RSV concentrations for both SLN and NLC in cell culture studies. RSV-NLC showed less fluorescence, indicating less ROS production in cytofluorometric studies. Ex vivo skin studies revealed that NLC are more efficient in carrying RSV to the epidermis. Conclusion This study suggests that both of the lipid nanoparticles had antioxidant properties at a concentration of 50 μM. When the two systems were compared, NLC penetrated deeper into the skin. RSV-loaded NLC with smaller PS and higher drug loading appears to be superior to SLN for dermal applications. PMID:22605933

  3. Chemical Enhancer Solubility in Human Stratum Corneum Lipids and Enhancer Mechanism of Action on Stratum Corneum Lipid Domain

    PubMed Central

    Ibrahim, Sarah A.; Li, S. Kevin

    2010-01-01

    Previously, chemical enhancer-induced permeation enhancement on human stratum corneum (SC) lipoidal pathway at enhancer thermodynamic activities approaching unity in the absence of cosolvents (defined as Emax) was determined and hypothesized to be related to the enhancer solubilities in the SC lipid domain. The objectives of the present study were to (a) quantify enhancer uptake into SC lipid domain at saturation, (b) elucidate enhancer mechanism(s) of action, and (c) study the SC lipid phase behavior at Emax. It was concluded that direct quantification of enhancer uptake into SC lipid domain using intact SC was complicated. Therefore a liposomal model of extracted human SC lipids was used. In the liposome study, enhancer uptake into extracted human SC lipid liposomes (EHSCLL) was shown to correlate with Emax. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and differential scanning calorimetry (DSC) were used to evaluate lipid phase alterations in enhancer-treated intact SC. IR spectra demonstrated an increase in the lipid domain fluidity and DSC thermograms indicated a decrease in the phase transition temperature with increasing Emax. These results suggest that the enhancer mechanism of action is through enhancer intercalation into SC intercellular lipids and subsequent lipid lamellae fluidization related to enhancer lipid concentration. PMID:19747970

  4. Metabolism. Part III: Lipids.

    ERIC Educational Resources Information Center

    Bodner, George M.

    1986-01-01

    Describes the metabolic processes of complex lipids, including saponification, activation and transport, and the beta-oxidation spiral. Discusses fatty acid degradation in regard to biochemical energy and ketone bodies. (TW)

  5. Lipid Metabolism Disorders

    MedlinePlus

    Metabolism is the process your body uses to make energy from the food you eat. Food is ... disorder, something goes wrong with this process. Lipid metabolism disorders, such as Gaucher disease and Tay-Sachs ...

  6. Cytarabine Lipid Complex Injection

    MedlinePlus

    Cytarabine lipid complex is used to treat lymphomatous meningitis (a type of cancer in the covering of ... to take.tell your doctor if you have meningitis. Your doctor will probably not want you to ...

  7. Lipid Suppression in CSI with Spatial Priors and Highly Undersampled Peripheral k-space

    PubMed Central

    Bilgic, Berkin; Gagoski, Borjan; Kok, Trina; Adalsteinsson, Elfar

    2012-01-01

    Mapping 1H brain metabolites using chemical shift imaging (CSI) is hampered by the presence of subcutaneous lipid signals, which contaminate the metabolites by ringing due to limited spatial resolution. Even though CSI at spatial resolution high enough to mitigate the lipid artifacts is infeasible due to signal-to-noise (SNR) constraints on the metabolites, the lipid signals have orders of magnitude higher concentration, which enables the collection of high-resolution lipid maps with adequate SNR. The previously proposed dual-density approach exploits this high-SNR property of the lipid layer to suppress truncation artifacts using high-resolution lipid maps. Another recent approach for lipid suppression makes use of the fact that metabolite and lipid spectra are approximately orthogonal, and seeks sparse metabolite spectra when projected onto lipid-basis functions. The present work combines and extends the dual-density approach and the lipid-basis penalty, while estimating the high-resolution lipid image from 2-average k-space data to incur minimal increase on the scan time. Further, we exploit the spectral-spatial sparsity of the lipid ring and propose to estimate it from substantially undersampled (acceleration R = 10 in the peripheral k-space) 2-average in vivo data using compressed sensing, and still obtain improved lipid suppression relative to using dual-density or lipid-basis penalty alone. PMID:22807147

  8. Reprint of "Mechanisms of lipid regulation and lipid gating in TRPC channels".

    PubMed

    Svobodova, Barbora; Groschner, Klaus

    2016-08-01

    TRPC proteins form cation channels that integrate and relay cellular signals by mechanisms involving lipid recognition and lipid-dependent gating. The lipohilic/amphiphilic molecules that function as cellular activators or modulators of TRPC proteins span a wide range of chemical structures. In this context, cellular redox balance is likely linked to the lipid recognition/gating features of TRPC channels. Both classical ligand-protein interactions as well as indirect and promiscuous sensory mechanisms have been proposed. Some of the recognition processes are suggested to involve ancillary lipid-binding scaffolds or regulators as well as dynamic protein-protein interactions determined by bilayer architecture. A complex interplay of protein-protein and protein-lipid interactions is likely to govern the gating and/or plasma membrane recruitment of TRPC channels, thereby providing a distinguished platform for signal integration and coincident signal detection. Both the primary molecular event(s) of lipid recognition by TRPC channels as well as the transformation of these events into distinct gating movements is poorly understood at the molecular level, and it remains elusive whether lipid sensing in TRPCs is conferred to a distinct sensor domain. Recent structural information on the molecular action of lipophilic activators in distantly related members of the TRP superfamily encourages speculations on TRPC gating mechanisms involved in lipid recognition/gating. This review aims to provide an update on the current understanding of the lipid-dependent control of TRPC channels with focus on the TRPC lipid sensing, signal-integration hub and a short discussion of potential links to redox signaling. PMID:27431463

  9. The Potent In Vitro Skin Permeation of Archaeosome Made from Lipids Extracted of Sulfolobus acidocaldarius

    PubMed Central

    Moghimipour, Eskandar; Kargar, Mohammad; Ramezani, Zahra; Handali, Somayeh

    2013-01-01

    Archaeosomes are a new generation of liposomes that exhibit higher stabilities under different conditions, such as high temperatures, alkaline or acidic pH, and presence of bile salts in comparison with liposomes, and can be used in biotechnology including drug, gene, and vaccine delivery. The objective of this study was to prepare archaeosomes using lipid extracted from Sulfolobus acidocaldarius and evaluate their physicochemical properties. The lipids were extracted from S. acidocaldarius and assayed by High Performance Thin-Layer Chromatography (HPTLC). Archaeosomes were prepared using film method and methylene blue was used as drug model. They were characterized for their vesicle size and Differential Scanning Calorimetry (DSC) was used to investigate changes in their thermal behavior. The released amount of methylene blue was determined using a dialysis membrane and rat skin. HPTLC analysis of the extracted lipids showed that glycerol ether may be the major lipid with more than 78 percent probability. Results of particle size determination showed a mean size of 158.33 nm and the results of DSC indicated the possible interaction of methylene blue with lipids during the preparation of archaeosome. The addition of cholesterol significantly improved the encapsulation of methylene blue in the archaeosome so that the encapsulation efficiency was 61.66 ± 2.88%. The result of in vitro skin permeation showed that methylene blue could pass through skin model according to Peppas model and there was about 41.66% release after 6 h, whereas no release was observed through dialysis membrane. According to the results of the study, it is concluded that archaeosome may be successfully used as drug delivery system. PMID:24453698

  10. Interaction of C(60) fullerene with lipids.

    PubMed

    Cataldo, Franco

    2010-06-01

    Unsaturated lipids when exposed to air at room temperature undergo a slow autoxidation. When fullerene C(60) was dissolved in selected lipids (ethyl oleate, ethyl linoleate, linseed oil and castor oil) the spectrophotometric analysis shows that the oxidation is concentrated to C(60) which is converted to an epoxide C(60)O. Thus, fullerene C(60) displays antioxidant activity not only when dissolved in unsaturated lipids but also, more generally, when dissolved in unsaturated solvents subjected to autoxidation like, for example, in cyclohexene. The behaviour of C(60) in ethyl oleate has been compared with that of the known antioxidant TMPPD (N,N',N,N,'-tetramethyl-p-phenylenediamine) in ethyl oleate. The mechanism of the antioxidant action of C(60) in lipids has been proposed. The kinetics of C(60) oxidation in lipids was determined spectrophotometrically both at room temperature in the dark and under UV irradiation. The oxidized products derived from C(60) photo-oxidation in lipids have been identified. PMID:20338159

  11. Design, Synthesis of Novel Lipids as Chemical Permeation Enhancers and Development of Nanoparticle System for Transdermal Drug Delivery

    PubMed Central

    Shah, Punit P.; Etukala, Jagan Reddy; Vemuri, Adithi; Singh, Mandip

    2013-01-01

    In the present study, we designed and developed novel lipids that include (Z)-1-(Octadec-9-en-1-yl)-pyrrolidine (Cy5T), 1, 1-Di-((Z)-octadec-9-en-1-yl)pyrrolidin-1-ium iodide (Cy5), (Z)-1-(Octadec-9-en-1-yl)-piperidine (Cy6T), and 1, 1-Di-((Z)-octadec-9-en-1-yl) piperidin-1-ium iodide (Cy6) to enhance the transdermal permeation of some selected drugs. Firstly, we evaluated the transdermal permeation efficacies of these lipids as chemical permeation enhancers in vehicle formulations for melatonin, ß-estradiol, caffeine, α-MSH, and spantide using franz diffusion cells. Among them Cy5 lipid was determined to be the most efficient by increasing the transdermal permeation of melatonin, ß-estradiol, caffeine, α-MSH, and spantide by 1.5 to 3.26-fold more at the epidermal layer and 1.3 to 2.5-fold more at the dermal layer, in comparison to either NMP or OA. Hence we developed a nanoparticle system (cy5 lipid ethanol drug nanoparticles) to evaluate any further improvement in the drug penetration. Cy5 lipid formed uniformly sized nanoparticles ranging from 150–200 nm depending on the type of drug. Further, Cy5 based nanoparticle system significantly (p<0.05) increased the permeation of all the drugs in comparison to the lipid solution and standard permeation enhancers. There were about 1.54 to 22-fold more of drug retained in the dermis for the Cy5 based nanoparticles compared to OA/NMP standard enhancers and 3.87 to 66.67-fold more than lipid solution. In addition, epifluorescent microscopic analysis in rhodamine-PE permeation studies confirmed the superior permeation enhancement of LEDs (detection of fluorescence up to skin depth of 340 μm) more than lipid solution, which revealed fluorescence up to skin depth of only 260 μm. In summary the present findings demonstrate that i) cationic lipid with 5 membered amine heterocyclic ring has higher permeating efficacy than the 6 membered amine hertocyclic ring. ii) The nanoparticle system prepared with Cy5 showed

  12. Results of tests on a Rockwell International space shuttle orbiter (-139 configuration) 0.0175-scale model (no. 29-0) in AEDC tunnel B to determine boundary layer characteristics

    NASA Technical Reports Server (NTRS)

    Quan, M.

    1975-01-01

    Results of wind tunnel tests were conducted to determine boundary layer characteristics on the lower surface of a space shuttle orbiter. Total pressure and temperature profile data at various model stations were obtained using a movable, four-degree-of-freedom probe mechanism and static pressure taps on the model surface. During a typical run, the probe was located over a preselected model location, then driven down through the bondary layer until contact was made with the model surface.

  13. Lipid extraction from microalgae using a single ionic liquid

    DOEpatents

    Salvo, Roberto Di; Reich, Alton; Dykes, Jr., H. Waite H.; Teixeira, Rodrigo

    2013-05-28

    A one-step process for the lysis of microalgae cell walls and separation of the cellular lipids for use in biofuel production by utilizing a hydrophilic ionic liquid, 1-butyl-3-methylimidazolium. The hydrophilic ionic liquid both lyses the microalgae cell walls and forms two immiscible layers, one of which consists of the lipid contents of the lysed cells. After mixture of the hydrophilic ionic liquid with a suspension of microalgae cells, gravity causes a hydrophobic lipid phase to move to a top phase where it is removed from the mixture and purified. The hydrophilic ionic liquid is recycled to lyse new microalgae suspensions.

  14. Lipid membranes for membrane proteins.

    PubMed

    Kukol, Andreas

    2015-01-01

    The molecular dynamics (MD) simulation of membrane proteins requires the setup of an accurate representation of lipid bilayers. This chapter describes the setup of a lipid bilayer system from scratch using generally available tools, starting with a definition of the lipid molecule POPE, generation of a lipid bilayer, energy minimization, MD simulation, and data analysis. The data analysis includes the calculation of area and volume per lipid, deuterium order parameters, self-diffusion constant, and the electron density profile. PMID:25330959

  15. Major lipid classes and their fatty acids in a parasitic nematode, Ascaridia galli.

    PubMed

    Ghosh, Amit; Kar, Kumkum; Ghosh, D; Dey, C; Misra, K K

    2010-04-01

    The paper presents major lipid classes and their fatty acids investigated from Ascaridia galli, a nematode parasite of country fowl. Thin layer chromatography (TLC) reveals that the percent of total lipid, neutral lipid, phospholipids, and glycolipids are 1.94, 54.39, 26.95 and 18.66, respectively. Gas-liquid chromatography (GLC) analysis shows that the saturated fatty acids are the major components in all the lipid fractions followed by monoenes and dienes. Polyunsaturated fatty acids (PUFA) were present in low amount. Stearic acids (C(18)) were the chief components among all the fatty acids in all the lipid fractions. PMID:21526035

  16. Nanometric Gap Structure with a Fluid Lipid Bilayer for the Selective Transport and Detection of Biological Molecules.

    PubMed

    Ando, Koji; Tanabe, Masashi; Morigaki, Kenichi

    2016-08-01

    The biological membrane is a natural biosensing platform that can detect specific molecules with extremely high sensitivity. We developed a biosensing methodology by combining a model biological membrane and a nanometer-sized gap structure on a glass substrate. The model membrane comprised lithographically patterned polymeric and fluid lipid bilayers. The polymeric bilayer was bonded to a poly(dimethylsiloxane) (PDMS) sheet by using an adhesion layer with a defined thickness (lipid vesicles). Extruded lipid vesicles having a biotin moiety on the surface were used as the adhesion layer in conjunction with the biotin-streptavidin linkage. A gap structure was formed between the fluid bilayer and PDMS (nanogap junction). The thickness of the gap structure was several tens of nanometers, as determined by the thickness of the adhesion layer. The nanogap junction acted as a sensitive biosensing platform. From a mixture of proteins (cholera toxin and albumin), the target protein (cholera toxin) was selectively transported into the gap by the specific binding to a glycolipid (GM1) in the fluid bilayer and lateral diffusion. The target protein molecules were then detected with an elevated signal-to-noise ratio due to the reduced background noise in the nanometric gap. The combination of selective transport and reduced background noise drastically enhanced the sensitivity toward the target protein. The nanogap junction should have broad biomedical applications by realizing highly selective and sensitive biosensing in samples having diverse coexisting molecules. PMID:27427950

  17. Scoparone affects lipid metabolism in primary hepatocytes using lipidomics.

    PubMed

    Zhang, Aihua; Qiu, Shi; Sun, Hui; Zhang, Tianlei; Guan, Yu; Han, Ying; Yan, Guangli; Wang, Xijun

    2016-01-01

    Lipidomics, which focuses on the global study of molecular lipids in biological systems, could provide valuable insights about disease mechanisms. In this study, we present a nontargeted lipidomics strategy to determine cellular lipid alterations after scoparone exposure in primary hepatocytes. Lipid metabolic profiles were analyzed by high-performance liquid chromatography coupled with time-of-flight mass spectrometry, and a novel imaging TransOmics tool has been developed for the analysis of high-resolution MS data, including the data pretreatment, visualization, automated identification, deconvolution and quantification of lipid species. Chemometric and statistical analyses of the obtained lipid fingerprints revealed the global lipidomic alterations and tested the therapeutic effects of scoparone. Identification of ten proposed lipids contributed to the better understanding of the effects of scoparone on lipid metabolism in hepatocytes. The most striking finding was that scoparone caused comprehensive lipid changes, as represented by significant changes of the identificated lipids. The levels of identified PG(19:1(9Z)/14:0), PE(17:1(9Z)/0:0), PE(19:1(9Z)/0:0) were found to be upregulated in ethanol-induced group, whereas the levels in scoparone group were downregulated. Lipid metabolism in primary hepatocytes was changed significantly by scoparone treatment. We believe that this novel approach could substantially broaden the applications of high mass resolution mass spectrometry for cellular lipidomics. PMID:27306123

  18. Scoparone affects lipid metabolism in primary hepatocytes using lipidomics

    PubMed Central

    Zhang, Aihua; Qiu, Shi; Sun, Hui; Zhang, Tianlei; Guan, Yu; Han, Ying; Yan, Guangli; Wang, Xijun

    2016-01-01

    Lipidomics, which focuses on the global study of molecular lipids in biological systems, could provide valuable insights about disease mechanisms. In this study, we present a nontargeted lipidomics strategy to determine cellular lipid alterations after scoparone exposure in primary hepatocytes. Lipid metabolic profiles were analyzed by high-performance liquid chromatography coupled with time-of-flight mass spectrometry, and a novel imaging TransOmics tool has been developed for the analysis of high-resolution MS data, including the data pretreatment, visualization, automated identification, deconvolution and quantification of lipid species. Chemometric and statistical analyses of the obtained lipid fingerprints revealed the global lipidomic alterations and tested the therapeutic effects of scoparone. Identification of ten proposed lipids contributed to the better understanding of the effects of scoparone on lipid metabolism in hepatocytes. The most striking finding was that scoparone caused comprehensive lipid changes, as represented by significant changes of the identificated lipids. The levels of identified PG(19:1(9Z)/14:0), PE(17:1(9Z)/0:0), PE(19:1(9Z)/0:0) were found to be upregulated in ethanol-induced group, whereas the levels in scoparone group were downregulated. Lipid metabolism in primary hepatocytes was changed significantly by scoparone treatment. We believe that this novel approach could substantially broaden the applications of high mass resolution mass spectrometry for cellular lipidomics. PMID:27306123

  19. Influences of the Structure of Lipids on Thermal Stability of Lipid Membranes

    NASA Astrophysics Data System (ADS)

    Hai, Nan-Nan; Zhou, Xin; Li, Ming

    2015-08-01

    The binding free energy (BFE) of lipid to lipid bilayer is a critical factor to determine the thermal or mechanical stability of the bilayer. Although the molecular structure of lipids has significant impacts on BFE of the lipid, there lacks a systematic study on this issue. In this paper we use coarse-grained molecular dynamics simulation to investigate this problem for several typical phospholipids. We find that both the tail length and tail unsaturation can significantly affect the BFE of lipids but in opposite way, namely, BFE decreases linearly with increasing length, but increases linearly with addition of unsaturated bonds. Inspired by the specific structure of cholesterol which is a crucial component of biomembrane, we also find that introduction of carbo-ring-like structures to the lipid tail or to the bilayer may greatly enhance the stability of the bilayer. Our simulation also shows that temperature can influence the bilayer stability and this effect can be significant when the bilayer undergoes phase transition. These results may be helpful to the design of liposome or other self-assembled lipid systems. Support by the National Natural Science Foundation of China under Grant Nos. 91027046 and 11105218.

  20. A comparative study: the impact of different lipid extraction methods on current microalgal lipid research

    PubMed Central

    2014-01-01

    Microalgae cells have the potential to rapidly accumulate lipids, such as triacylglycerides that contain fatty acids important for high value fatty acids (e.g., EPA and DHA) and/or biodiesel production. However, lipid extraction methods for microalgae cells are not well established, and there is currently no standard extraction method for the determination of the fatty acid content of microalgae. This has caused a few problems in microlagal biofuel research due to the bias derived from different extraction methods. Therefore, this study used several extraction methods for fatty acid analysis on marine microalga Tetraselmis sp. M8, aiming to assess the potential impact of different extractions on current microalgal lipid research. These methods included classical Bligh & Dyer lipid extraction, two other chemical extractions using different solvents and sonication, direct saponification and supercritical CO2 extraction. Soxhlet-based extraction was used to weigh out the importance of solvent polarity in the algal oil extraction. Coupled with GC/MS, a Thermogravimetric Analyser was used to improve the quantification of microalgal lipid extractions. Among these extractions, significant differences were observed in both, extract yield and fatty acid composition. The supercritical extraction technique stood out most for effective extraction of microalgal lipids, especially for long chain unsaturated fatty acids. The results highlight the necessity for comparative analyses of microalgae fatty acids and careful choice and validation of analytical methodology in microalgal lipid research. PMID:24456581