WorldWideScience

Sample records for fluid phospholipid membranes

  1. Biophysical properties of membrane lipids of anammox bacteria : I. Ladderane phospholipids form highly organized fluid membranes

    NARCIS (Netherlands)

    Boumann, Henry A.; Longo, Marjorie L.; Stroeve, Pieter; Poolman, Bert; Hopmans, Ellen C.; Stuart, Marc C. A.; Damste, Jaap S. Sinninghe; Schouten, Stefan

    Anammox bacteria that are capable of anaerobically oxidizing ammonium (anammox) with nitrite to nitrogen gas produce unique membrane phospholipids that comprise hydrocarbon chains with three or five linearly condensed cyclobutane rings. To gain insight into the biophysical properties of these

  2. Co-existence of Gel and Fluid Lipid Domains in Single-component Phospholipid Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Armstrong, Clare L [McMaster University; Barrett, M [McMaster University; Toppozini, L [McMaster University; Yamani, Zahra [Canadian Neutron Beam Centre, National Research Council, Chalk River Laboratorie; Kucerka, Norbert [Canadian Neutron Beam Centre and Comelius University (Slovakia); Katsaras, John [ORNL; Fragneto, Giovanna [Institut Laue-Langevin (ILL); Rheinstadter, Maikel C [McMaster University

    2012-01-01

    Lateral nanostructures in membranes, so-called rafts, are believed to strongly influence membrane properties and functions. The experimental observation of rafts has proven difficult as they are thought to be dynamic structures that likely fluctuate on nano- to microsecond time scales. Using neutron diffraction we present direct experimental evidence for the co-existence of gel and fluid lipid domains in a single-component phospholipid membrane made of DPPC as it undergoes its main phase transition. The coherence length of the neutron beam sets a lower limit for the size of structures that can be observed. Neutron coherence lengths between 30 and 242A used in this study were obtained by varying the incident neutron energy and the resolution of the neutron spectrometer. We observe Bragg peaks corresponding to co-existing nanometer sized structures, both in out-of-plane and in-plane scans, by tuning the neutron coherence length. During the main phase transition, instead of a continuous transition that shows a pseudo-critical behavior, we observe the co-existence of gel and fluid domains.

  3. Thermodynamics of Indomethacin Adsorption to Phospholipid Membranes.

    Science.gov (United States)

    Fearon, Amanda D; Stokes, Grace Y

    2017-11-22

    Using second-harmonic generation, we directly monitored adsorption of indomethacin, a nonsteroidal anti-inflammatory drug, to supported lipid bilayers composed of phospholipids of varying phase, cholesterol content, and head group charge without the use of extrinsic labels at therapeutically relevant aqueous concentrations. Indomethacin adsorbed to gel-phase lipids with a high binding affinity, suggesting that like other arylacetic acid-containing drugs, it preferentially interacts with ordered lipid domains. We discovered that adsorption of indomethacin to gel-phase phospholipids was endothermic and entropically driven, whereas adsorption to fluid-phase phospholipids was exothermic and enthalpically driven. As temperature increased from 19 to 34 °C, binding affinities to gel-phase lipids increased by 7-fold but relative surface concentration decreased to one-fifth of the original value. We also compared our results to the entropies reported for indomethacin adsorbed to surfactant micelles, which are used in drug delivery systems, and assert that adsorbed water molecules in the phospholipid bilayer may be buried deeper into the acyl chains and less accessible for disruption. The thermodynamic studies reported here provide mechanistic insight into indomethacin interactions with mammalian plasma membranes in the gastrointestinal tract and inform studies of drug delivery, where indomethacin is commonly used as a prototypical, hydrophobic small-molecule drug.

  4. Molecular dynamics simulation of a phospholipid membrane

    NARCIS (Netherlands)

    Egberts, Egbert; Marrink, Siewert-Jan; Berendsen, Herman J.C.

    We present the results of molecular dynamics (MD) simulations of a phospholipid membrane in water, including full atomic detail. The goal of the simulations was twofold: first we wanted to set up a simulation system which is able to reproduce experimental results and can serve as a model membrane in

  5. Novicidin interactions with phospholipid membranes

    DEFF Research Database (Denmark)

    Balakrishnan, Vijay Shankar

    Antimicrobial peptides target bacterial cell membranes and are considered as potential antibiotics. Their interactions with cell membranes are studied using different approaches. This thesis comprises of the biophysical investigations on the antimicrobial peptide Novicidin, interacting with lipos......Antimicrobial peptides target bacterial cell membranes and are considered as potential antibiotics. Their interactions with cell membranes are studied using different approaches. This thesis comprises of the biophysical investigations on the antimicrobial peptide Novicidin, interacting...... with liposomes. The lipid-induced changes in the peptide due to membrane binding, and the peptide-induced changes in the membrane properties were investigated using various spectroscopic and calorimetric methods, and the structural and thermodynamic aspects of peptide-lipid interactions are discussed. This helps...

  6. Computer simulations of phospholipid - membrane thermodynamic fluctuations

    DEFF Research Database (Denmark)

    Pedersen, U.R.; Peters, Günther H.j.; Schröder, T.B.

    2008-01-01

    This paper reports all-atom computer simulations of five phospholipid membranes, DMPC, DPPC, DMPG, DMPS, and DMPSH, with a focus on the thermal equilibrium fluctuations of volume, energy, area, thickness, and order parameter. For the slow fluctuations at constant temperature and pressure (defined...... membranes, showing a similar picture. The cause of the observed strong correlations is identified by splitting volume and energy into contributions from tails, heads, and water, showing that the slow volume-energy fluctuations derive from the tail region’s van der Waals interactions and are thus analogous...

  7. Interaction of abscisic acid with phospholipid membranes

    International Nuclear Information System (INIS)

    Stillwell, W.; Brengle, B.; Hester, P.; Wassall, S.T.

    1989-01-01

    The plant hormone abscisic acid (ABA) is shown, under certain conditions, to greatly enhance the permeability of phospholipid bilayer membranes to the nonelectrolyte erythritol (followed spectrophotometrically by osmotic swelling) and the anion carboxyfluorescein (followed by fluorescence). The hormone is ineffective with single- and mixed-component phosphatidylcholine membranes in the liquid-crystalline or gel states. In contrast, substantial ABA-induced permeability is measured for two-component membranes containing lipids with different polar head groups or containing phosphatidylcholines with different acyl chains at temperatures where gel and liquid-crystalline phases coexist. Despite the large ABA-induced enhancement in bilayer permeability, no evidence for a substantial change at the molecular level was seen in the membranes by magnetic resonance techniques. 13 C NMR spin-lattice relaxation times, T 1 , in sonicated unilamellar vesicles and ESR of spin-labeled fatty acids intercalated into membranes showed negligible effect on acyl chain order and dynamics within the bilayer, while 31 P NMR of sonicated unilamellar vesicles indicated negligible effect on molecular motion and conformation in the head-group region. The authors propose that, instead of causing a general nonspecific perturbation to the membrane, the hormone acts at membrane defects formed due to mismatch in molecular packing where two different head groups or acyl chain states interface. Increased membrane disruption by ABA at these points of membrane instability could then produce an enhancement in permeability

  8. Variations in fluid chemistry and membrane phospholipid fatty acid composition of the bacterial community in a cold storage groundwater system during clogging events

    International Nuclear Information System (INIS)

    Vetter, Alexandra; Mangelsdorf, Kai; Wolfgramm, Markus; Rauppach, Kerstin; Schettler, Georg; Vieth-Hillebrand, Andrea

    2012-01-01

    In order to monitor the operating mode of the cold storage of the German Parliament (North German Basin) the fluid chemistry and the phospholipid fatty acid (PLFA) composition of the indigenous microbial community have been monitored from August 2006 to August 2009. During this time two periods of reduced injection (clogging events) characterized by Fe precipitates and microbial biofilms in filters occurred in the injection wells impairing the operating state of the investigated cold storage. The fluid monitoring revealed the presence of sufficient amounts of potential C and energy sources (e.g. DOC and SO 4 2- ) in the process water to sustain microbial life in the cold storage. In times of reduced injection the PLFA inventory of the microbial community differs significantly from times of normal operating phases indicating compositional changes in the indigenous microbial ecosystem. The most affected fatty acids (FAs) are 16:1ω7c (increase), 16:1ω7t (decrease) and 18:1ω7c (increase), interpreted to originate mainly from Fe and S oxidizers, as well as branched FA with 15, 16 and 17 C atoms (decrease) most likely representing sulfate-reducing bacteria (SRB). Based on this variability, PLFA ratios have been created to reflect the increasing dominance of biofilm forming S and Fe oxidizers during the disturbance periods. These ratios are potential diagnostic tools to assess the microbiological contribution to the clogging events and to find appropriate counteractive measures (e.g. mechanical cleaning vs disinfection). The correlation between changes in the PLFA composition and the operational state suggests that microbially mediated processes play a significant role in the observed clogging events in the investigated cold storage.

  9. Cholesterol autoxidation in phospholipid membrane bilayers

    International Nuclear Information System (INIS)

    Sevanian, A.; McLeod, L.L.

    1987-01-01

    Lipid peroxidation in unilamellar liposomes of known cholesterol-phospholipid composition was monitored under conditions of autoxidation or as induced by a superoxide radical generating system, gamma-irradiation or cumene hydroperoxide. Formation of cholesterol oxidation products was indexed to the level of lipid peroxidation. The major cholesterol oxidation products identified were 7-keto-cholesterol, isomeric cholesterol 5,6-epoxides, isomeric 7-hydroperoxides and isomeric 3,7-cholestane diols. Other commonly encountered products included 3,5-cholestadiene-7-one and cholestane-3 beta, 5 alpha, 6 beta-triol. Superoxide-dependent peroxidation required iron and produced a gradual increase in 7-keto-cholesterol and cholesterol epoxides. Cholesterol oxidation was greatest in liposomes containing high proportions of unsaturated phospholipid to cholesterol (4:1 molar ratio), intermediate with low phospholipid to cholesterol ratios (2:1) and least in liposomes prepared with dipalmitoylphosphatidylcholine and cholesterol. This relationship held regardless of the oxidizing conditions used. Cumene hydroperoxide-dependent lipid peroxidation and/or more prolonged oxidations with other oxidizing systems yielded a variety of products where cholesterol-5 beta,6 beta-epoxide, 7-ketocholesterol and the 7-hydroperoxides were most consistently elevated. Oxyradical initiation of lipid peroxidation produced a pattern of cholesterol oxidation products distinguishable from the pattern derived by cumene hydroperoxide-dependent peroxidation

  10. Effect of phospholipid metabolites on model membrane fusion

    Energy Technology Data Exchange (ETDEWEB)

    Shragin, A.S.; Vasilenko, I.A.; Selishcheva, A.A.; Shvets, V.I.

    1985-01-01

    /sup 31/P-NMR spectroscopy and formation of fluorescent complexes between Tb/sup 3 +/ and dipicolinic acid were used to monitor liposome fusion and the effects of phospholipases C and D on the process. Phospholipase C was found highly efficient in initiating liposomal fusion, regardless of the phospholipid composition of the bilayer membranes. However, phospholipase D promoted liposomal fusion only in cases in which the membranes contained high concentrations of phospholipids incapable of forming bilayer membranes, such as phosphatidylethanolamine and cardiolipin. The mechanism of action of both enzymes in promoting liposomal fusion was ascribed to the generation of a metastable state in the membranes as a result of enzymatic formation of lipophilic metabolites 1,2-diacylglycerol and phosphatidic acid. The perturbation, or fluidity, of the liposomal membranes favored fusion on contact. 21 references, 4 figures.

  11. Mechanics and dynamics of triglyceride-phospholipid model membranes

    DEFF Research Database (Denmark)

    Pakkanen, Kirsi I.; Duelund, Lars; Qvortrup, Klaus

    2011-01-01

    We demonstrate here that triolein alters the mechanical properties of phospholipid membranes and induces extraordinary conformational dynamics. Triolein containing membranes exhibit fluctuations up to size range of 100µm and with the help of these are e.g. able to squeeze through narrow passages...... with larger lamellar distances observed in the TOPOPC membranes. These findings suggest repulsion between adjacent membranes. We provide a comprehensive discussion on the possible explanations for the observed mechanics and dynamics in the TOPOPC system and on their potential cellular implications....

  12. Behavior of 4-Hydroxynonenal in Phospholipid Membranes

    Czech Academy of Sciences Publication Activity Database

    Vazdar, Mario; Jurkiewicz, Piotr; Hof, Martin; Jungwirth, Pavel; Cwiklik, Lukasz

    2012-01-01

    Roč. 116, č. 22 (2012), s. 6411-6415 ISSN 1520-6106 R&D Projects: GA ČR GA203/08/0114; GA ČR GAP208/10/0376; GA MŠk LH12001; GA AV ČR GEMEM/09/E006 Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z40400503 Keywords : fluorescence spectroscopy * molecular dynamics * membrane s * 4-hydroxynonenal Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.607, year: 2012

  13. Phospholipids Polysaccharide and Its Application as Inhibitive Drilling Fluid Additive

    Science.gov (United States)

    Gu, Xue-Fan; Hu, Wei-Min; Zhang, Fan; Du, Wei-Chao; Zhang, Qiang; Zhang, Jie; Zhang, Yong-Ming; Chen, Gang

    2018-03-01

    For the improvement of solubility and the performance of the sample that derived plant polysaccharide(SJ) in drilling fluid based on water, which was improved by phosphoric esterification with phospholipids reagent. The conditions of the reaction were discussed by orthogonal ways in four factors and three levels, and the optimization of handling approaches were found out: With pH=12 at the temperature of 80°C, the mass ratio between phospholipids agent and SJ is 0.1g/1g. The viscosity about the system added by sulfonated SJ (SJP) was extremely increased and below 120°, rheological properties had a slight change. The inhibitive ability of SJP is assessed by the mud ball immersing tests and clay-swelling experiments, that is apparently better than SJ and even 4wt% KCl in free water.

  14. Lipid chain saturation and the cholesterol in the phospholipid membrane affect the spectroscopic properties of lipophilic dye nile red

    Science.gov (United States)

    Halder, Animesh; Saha, Baishakhi; Maity, Pabitra; Kumar, Gopinatha Suresh; Sinha, Deepak Kumar; Karmakar, Sanat

    2018-02-01

    We have studied the effect of composition and the phase state of phospholipid membranes on the emission spectrum, anisotropy and lifetime of a lipophilic fluorescence probe nile red. Fluorescence spectrum of nile red in membranes containing cholesterol has also been investigated in order to get insights into the influence of cholesterol on the phospholipid membranes. Maximum emission wavelength (λem) of nile red in the fluid phase of saturated and unsaturated phospholipids was found to differ by 10 nm. The λem was also found to be independent of chain length and charge of the membrane. However, the λem is strongly dependent on the temperature in the gel phase. The λem and rotational diffusion rate decrease, whereas the anisotropy and lifetime increase markedly with increasing cholesterol concentration for saturated phosoholipids, such as, dimyristoyl phosphatidylcholine (DMPC) in the liquid ordered phase. However, these spectroscopic properties do not alter significantly in case of unsaturated phospholipids, such as, dioleoyl phosphatidylcholine (DOPC) in liquid disordered phase. Interestingly, red edge excitation shift (REES) in the presence of lipid-cholesterol membranes is the direct consequences of change in rotational diffusion due to motional restriction of lipids in the presence of cholesterol. This study provides correlations between the membrane compositions and fluorescence spectral features which can be utilized in a wide range of biophysical fields as well the cell biology.

  15. Characterization of phospholipid composition and its control in the plasma membrane of developing soybean root

    International Nuclear Information System (INIS)

    Whitman, C.E.

    1985-01-01

    The phospholipid composition of plasma membrane enriched fractions from developing soybean root and several mechanisms which may regulate it have been examined. Plasma membrane vesicles were isolated from meristematic and mature sections of four-day-old dark grown soybean roots (Glycine max [L.] Merr. Cult. Wells II). Analysis of lipid extracts revealed two major phospholipid classes: phosphatidylcholine and phosphatidylethanolamine. Minor phospholipid classes were phosphatidylinositol, phosphatidylserine, phosphatidylgylcerol and diphosphatidylgylcerol. Phospholipid composition was similar at each developmental stage. Fatty acids of phosphatidylcholine and phosphatidylethanolamine were 16:0, 18:0, 18:2, and 18:3. Fatty acid composition varied with both phospholipid class and the developmental stage of the root. The degradation of phosphatidylcholine by endogenous phospholipase D during membrane isolation indicated that this enzyme might be involved in phospholipid turnover within the membrane. Phospholipase D activity was heat labile and increasing the pH of the enzyme assay from 5.3 to 7.8 resulted in 90% inhibition of activity. The turnover of fatty acids within the phospholipids of the plasma membrane was studied. Mature root sections were incubated with [1- 14 C] acetate, 1 mM Na acetate and 50 μg/ml chloramphenicol. Membrane lipid extracts analyzed for phospholipid class and acyl chain composition revealed that the long incubation times did not alter the phospholipid composition of the plasma membrane enriched fraction

  16. Biophysical studies of cholesterol in unsaturated phospholipid model membranes

    Science.gov (United States)

    Williams, Justin Adam

    Cellular membranes contain a staggering diversity of lipids. The lipids are heterogeneously distributed to create regions, or domains, whose physical properties differ from the bulk membrane and play an essential role in modulating the function of resident proteins. Many basic questions pertaining to the formation of these lateral assemblies remain. This research employs model membranes of well-defined composition to focus on the potential role of polyunsaturated fatty acids (PUFAs) and their interaction with cholesterol (chol) in restructuring the membrane environment. Omega-3 (n-3) PUFAs are the main bioactive components of fish oil, whose consumption alleviates a variety of health problems by a molecular mechanism that is unclear. We hypothesize that the incorporation of PUFAs into membrane lipids and the effect they have on molecular organization may be, in part, responsible. Chol is a major constituent in the plasma membrane of mammals. It determines the arrangement and collective properties of neighboring lipids, driving the formation of domains via differential affinity for different lipids. The molecular organization of 1-[2H31]palmitoyl-2-eicosapentaenoylphosphatidylcholine (PEPC-d31) and 1-[2H31]palmitoyl-2-docosahexaenoylphosphatidylcholine (PDPC-d31) in membranes with sphingomyelin (SM) and chol (1:1:1 mol) was compared by solid-state 2H NMR spectroscopy. Eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids are the two major n-3 PUFAs found in fish oil, while PEPC-d31 and PDPC-d31 are phospholipids containing the respective PUFAs at the sn-2 position and a perdeuterated palmitic acid at the sn-1 position. Analysis of spectra recorded as a function of temperature indicates that in both cases, formation of PUFA-rich (less ordered) and SM-rich (more ordered) domains occurred. A surprisingly substantial proportion of PUFA was found to infiltrate the more ordered domain. There was almost twice as much DHA (65%) as EPA (30%). The implication is that n-3

  17. Dynamic shaping of cellular membranes by phospholipids and membrane-deforming proteins.

    Science.gov (United States)

    Suetsugu, Shiro; Kurisu, Shusaku; Takenawa, Tadaomi

    2014-10-01

    All cellular compartments are separated from the external environment by a membrane, which consists of a lipid bilayer. Subcellular structures, including clathrin-coated pits, caveolae, filopodia, lamellipodia, podosomes, and other intracellular membrane systems, are molded into their specific submicron-scale shapes through various mechanisms. Cells construct their micro-structures on plasma membrane and execute vital functions for life, such as cell migration, cell division, endocytosis, exocytosis, and cytoskeletal regulation. The plasma membrane, rich in anionic phospholipids, utilizes the electrostatic nature of the lipids, specifically the phosphoinositides, to form interactions with cytosolic proteins. These cytosolic proteins have three modes of interaction: 1) electrostatic interaction through unstructured polycationic regions, 2) through structured phosphoinositide-specific binding domains, and 3) through structured domains that bind the membrane without specificity for particular phospholipid. Among the structured domains, there are several that have membrane-deforming activity, which is essential for the formation of concave or convex membrane curvature. These domains include the amphipathic helix, which deforms the membrane by hemi-insertion of the helix with both hydrophobic and electrostatic interactions, and/or the BAR domain superfamily, known to use their positively charged, curved structural surface to deform membranes. Below the membrane, actin filaments support the micro-structures through interactions with several BAR proteins as well as other scaffold proteins, resulting in outward and inward membrane micro-structure formation. Here, we describe the characteristics of phospholipids, and the mechanisms utilized by phosphoinositides to regulate cellular events. We then summarize the precise mechanisms underlying the construction of membrane micro-structures and their involvements in physiological and pathological processes. Copyright © 2014 the

  18. Influence of membrane phospholipid composition and structural organization on spontaneous lipid transfer between membranes.

    Science.gov (United States)

    Pankov, R; Markovska, T; Antonov, P; Ivanova, L; Momchilova, A

    2006-09-01

    Investigations were carried out on the influence of phospholipid composition of model membranes on the processes of spontaneous lipid transfer between membranes. Acceptor vesicles were prepared from phospholipids extracted from plasma membranes of control and ras-transformed fibroblasts. Acceptor model membranes with manipulated levels of phosphatidylethanolamine (PE), sphingomyelin and phosphatidic acid were also used in the studies. Donor vesicles were prepared of phosphatidylcholine (PC) and contained two fluorescent lipid analogues, NBD-PC and N-Rh-PE, at a self-quenching concentration. Lipid transfer rate was assessed by measuring the increase of fluorescence in acceptor membranes due to transfer of fluorescent lipid analogues from quenched donor to unquenched acceptor vesicles. The results showed that spontaneous NBD-PC transfer increased upon fluidization of acceptor vesicles. In addition, elevation of PE concentration in model membranes was also accompanied by an increase of lipid transfer to all series of acceptor vesicles. The results are discussed with respect to the role of lipid composition and structural order of cellular plasma membranes in the processes of spontaneous lipid exchange between membrane bilayers.

  19. Packing properties 1-alkanols and alkanes in a phospholipid membrane

    DEFF Research Database (Denmark)

    Westh, Peter

    2006-01-01

    We have used vibrating tube densitometry to investigate the packing properties of four alkanes and a homologous series of ten alcohols in fluid-phase membranes of dimyristoyl phosphatidylcholine (DMPC). It was found that the volume change of transferring these compounds from their pure states int...... into the membrane core, which is loosely packed. In this region, they partially occupy interstitial (or free-) volume, which bring about a denser molecular packing and generate a negative contribution to Vm(puremem)....... into the membrane, Vm(puremem), was positive for small (C4-C6) 1-alkanols while it was negative for larger alcohols and all alkanes. The magnitude of Vm(puremem) ranged from about +4 cm3/mol for alcohols with an alkyl chain about half the length of the fatty acids of DMPC, to -10 to -15 cm3/mol for the alkanes...

  20. Flip-flop of phospholipids in proteoliposomes reconstituted from detergent extract of chloroplast membranes: kinetics and phospholipid specificity.

    Directory of Open Access Journals (Sweden)

    Archita Rajasekharan

    Full Text Available Eukaryotic cells are compartmentalized into distinct sub-cellular organelles by lipid bilayers, which are known to be involved in numerous cellular processes. The wide repertoire of lipids, synthesized in the biogenic membranes like the endoplasmic reticulum and bacterial cytoplasmic membranes are initially localized in the cytosolic leaflet and some of these lipids have to be translocated to the exoplasmic leaflet for membrane biogenesis and uniform growth. It is known that phospholipid (PL translocation in biogenic membranes is mediated by specific membrane proteins which occur in a rapid, bi-directional fashion without metabolic energy requirement and with no specificity to PL head group. A recent study reported the existence of biogenic membrane flippases in plants and that the mechanism of plant membrane biogenesis was similar to that found in animals. In this study, we demonstrate for the first time ATP independent and ATP dependent flippase activity in chloroplast membranes of plants. For this, we generated proteoliposomes from Triton X-100 extract of intact chloroplast, envelope membrane and thylakoid isolated from spinach leaves and assayed for flippase activity using fluorescent labeled phospholipids. Half-life time of flipping was found to be 6 ± 1 min. We also show that: (a intact chloroplast and envelope membrane reconstituted proteoliposomes can flip fluorescent labeled analogs of phosphatidylcholine in ATP independent manner, (b envelope membrane and thylakoid reconstituted proteoliposomes can flip phosphatidylglycerol in ATP dependent manner, (c Biogenic membrane ATP independent PC flipping activity is protein mediated and (d the kinetics of PC translocation gets affected differently upon treatment with protease and protein modifying reagents.

  1. Employment of Voltammetry in Studies of Transport Processes across Artificial Phospholipid Membranes

    Czech Academy of Sciences Publication Activity Database

    Šestáková, Ivana; Navrátil, Tomáš; Josypčuk, Bohdan

    2016-01-01

    Roč. 28, č. 11 (2016), s. 2754-2759 ISSN 1040-0397 Institutional support: RVO:61388955 Keywords : phospholipid membrane * cadmium * calcium ionophore (calcimycin) Subject RIV: CG - Electrochemistry Impact factor: 2.851, year: 2016

  2. Covalent modification of serum transferrin with phospholipid and incorporation into liposomal membranes

    DEFF Research Database (Denmark)

    Afzelius, P; Demant, E J; Hansen, Gert Helge

    1989-01-01

    A method is described for incorporation of water-soluble proteins into liposomal membranes using covalent protein-phospholipid conjugates in detergent solution. A disulfide derivative of phosphatidylethanolamine containing a reactive N-hydroxysuccinimide ester group is synthesized, and the deriva......A method is described for incorporation of water-soluble proteins into liposomal membranes using covalent protein-phospholipid conjugates in detergent solution. A disulfide derivative of phosphatidylethanolamine containing a reactive N-hydroxysuccinimide ester group is synthesized...

  3. Checks and balances in membrane phospholipid class and acyl chain homeostasis, the yeast perspective

    NARCIS (Netherlands)

    de Kroon, A.I.P.M.|info:eu-repo/dai/nl/084765283; Rijken, P.J.|info:eu-repo/dai/nl/32716297X; De Smet, C.H.|info:eu-repo/dai/nl/304824224

    2013-01-01

    Glycerophospholipids are the most abundant membrane lipid constituents in most eukaryotic cells. As a consequence, phospholipid class and acyl chain homeostasis are crucial for maintaining optimal physical properties of membranes that in turn are crucial for membrane function. The topic of this

  4. Rooster sperm plasma membrane protein and phospholipid organization and reorganization attributed to cooling and cryopreservation

    Science.gov (United States)

    Cholesterol to phospholipid ratio is used as a representation for membrane fluidity, and predictor of cryopreservation success but results are not consistent across species and ignore the impact of membrane proteins. Therefore, this research explored the modulation of membrane fluidity and protein ...

  5. Preparation and evaluation of PEGylated phospholipid membrane coated layered double hydroxide nanoparticles

    Directory of Open Access Journals (Sweden)

    Mina Yan

    2016-06-01

    Full Text Available The aim of the present study was to develop layered double hydroxide (LDH nanoparticles coated with PEGylated phospholipid membrane. By comparing the size distribution and zeta potential, the weight ratio of LDH to lipid materials which constitute the outside membrane was identified as 2:1. Transmission electron microscopy photographs confirmed the core-shell structure of PEGylated phospholipid membrane coated LDH (PEG-PLDH nanoparticles, and cell cytotoxicity assay showed their good cell viability on Hela and BALB/C-3T3 cells over the concentration range from 0.5 to 50 μg/mL.

  6. An averaged polarizable potential for multiscale modeling in phospholipid membranes

    DEFF Research Database (Denmark)

    Witzke, Sarah; List, Nanna Holmgaard; Olsen, Jógvan Magnus Haugaard

    2017-01-01

    A set of average atom-centered charges and polarizabilities has been developed for three types of phospholipids for use in polarizable embedding calculations. The lipids investigated are 1,2-dimyristoyl-sn-glycero-3-phosphocholine, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, and 1-palmitoyl...

  7. Insulin stimulation of phospholipid methylation in isolated rat adipocyte plasma membranes.

    OpenAIRE

    Kelly, K L; Kiechle, F L; Jarett, L

    1984-01-01

    Partially purified plasma membranes prepared from rat adipocytes contain N-methyltransferase(s) that utilize(s) S-adenosyl-L-methionine to synthesize phosphatidylcholine from phosphatidylethanolamine. The incorporation of [3H]methyl from S-adenosyl-L-[methyl-3H]methionine into plasma membrane phospholipids was linear with incubation time and plasma membrane protein concentration and was inhibited in a dose-dependent manner by both S-adenosyl-L-homocysteine and 3-deazadenosine. The addition of...

  8. Relation between various phospholipase actions on human red cell membranes and the interfacial phospholipid pressure in monolayers

    NARCIS (Netherlands)

    Demel, R.A.; Geurts van Kessel, W.S.M.; Zwaal, R.F.A.; Roelofsen, B.; Deenen, L.L.M. van

    1975-01-01

    The action of purified phospholipases on monomolecular films of various interfacial pressures is compared with the action on erythrocyte membranes. The phospholipases which cannot hydrolyse phospholipids of the intact erythrocyte membrane, phospholipase C from Bacillus cereus, phospholipase A2 from

  9. Increased Binding of Calcium Ions at Positively Curved Phospholipid Membranes

    Czech Academy of Sciences Publication Activity Database

    Magarkar, Aniket; Jurkiewicz, Piotr; Allolio, Christoph; Hof, Martin; Jungwirth, Pavel

    2017-01-01

    Roč. 8, č. 2 (2017), s. 518-523 ISSN 1948-7185 R&D Projects: GA ČR(CZ) GA16-01074S; GA ČR(CZ) GAP207/12/0919 Grant - others:AV ČR(CZ) AP1102 Program:Akademická prémie - Praemium Academiae Institutional support: RVO:61388963 ; RVO:61388955 Keywords : molecular dynamics * fluorescence spectroscopy * calcium * phospholipids Subject RIV: CF - Physical ; Theoretical Chemistry; CF - Physical ; Theoretical Chemistry (UFCH-W) OBOR OECD: Physical chemistry; Physical chemistry (UFCH-W) Impact factor: 9.353, year: 2016

  10. Seasonal changes in minor membrane phospholipid classes, sterols and tocopherols in overwintering insect, Pyrrhocoris apterus

    Czech Academy of Sciences Publication Activity Database

    Košťál, Vladimír; Urban, T.; Řimnáčová, Lucie; Berková, Petra; Šimek, Petr

    2013-01-01

    Roč. 59, č. 9 (2013), s. 934-941 ISSN 0022-1910 R&D Projects: GA MŠk LH12103; GA MZd(CZ) NT11513 Institutional support: RVO:60077344 Keywords : seasonal membrane restructuring * phospholipids * lysophospholipids Subject RIV: ED - Physiology Impact factor: 2.500, year: 2013 http://www.sciencedirect.com/science/article/pii/S0022191013001406#

  11. Effect of heavy water on phospholipid membranes: experimental confirmation of molecular dynamics simulations

    Czech Academy of Sciences Publication Activity Database

    Beranová, Lenka; Humpolíčková, Jana; Sýkora, Jan; Benda, Aleš; Cwiklik, Lukasz; Jurkiewicz, Piotr; Gröbner, G.; Hof, Martin

    Roč. 14, č. 42 ( 2012 ), s. 14516-14522 ISSN 1463-9076 R&D Projects: GA AV ČR GEMEM/09/E006; GA ČR GBP208/12/G016 Institutional support: RVO:61388955 Keywords : phospholipid membranes * biophysics * physical chemistry Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.829, year: 2012

  12. Parallel artificial liquid membrane extraction as an efficient tool for removal of phospholipids from human plasma

    DEFF Research Database (Denmark)

    Ask, Kristine Skoglund; Bardakci, Turgay; Parmer, Marthe Petrine

    2016-01-01

    Generic Parallel Artificial Liquid Membrane Extraction (PALME) methods for non-polar basic and non-polar acidic drugs from human plasma were investigated with respect to phospholipid removal. In both cases, extractions in 96-well format were performed from plasma (125μL), through 4μL organic...

  13. Membrane phospholipids and radiation-induced death of mammalian cells

    International Nuclear Information System (INIS)

    Wolters, H.

    1987-01-01

    Radiation-induced cell killing is generally believed to be a consequence of residual DNA damage or damage that is mis-repaired. However, besides this DNA damage, damage to other molecules or structures of the cell may be involved in the killing. Especially membranes have been suggested as a determinant in cellular radiosensitivity. In this thesis experiments are described, dealing with the possible involvement of membranes in radiation-induced killing of mammalian cells. A general treatise of membrane structure is followed by information concerning deleterious effects of radiation on membranes. Consequences of damage to structure and function of membranes are reviewed. Thereafter evidence relating to the possible involvement of membranes in radiation-induced cell killing is presented. (Auth.)

  14. (CryoTransmission Electron Microscopy of Phospholipid Model Membranes Interacting with Amphiphilic and Polyphilic Molecules

    Directory of Open Access Journals (Sweden)

    Annette Meister

    2017-10-01

    Full Text Available Lipid membranes can incorporate amphiphilic or polyphilic molecules leading to specific functionalities and to adaptable properties of the lipid bilayer host. The insertion of guest molecules into membranes frequently induces changes in the shape of the lipid matrix that can be visualized by transmission electron microscopy (TEM techniques. Here, we review the use of stained and vitrified specimens in (cryoTEM to characterize the morphology of amphiphilic and polyphilic molecules upon insertion into phospholipid model membranes. Special emphasis is placed on the impact of novel synthetic amphiphilic and polyphilic bolalipids and polymers on membrane integrity and shape stability.

  15. Physiological levels of diacylglycerols in phospholipid membranes induce membrane fusion and stabilize inverted phases

    International Nuclear Information System (INIS)

    Siegel, D.P.; Banschbach, J.; Alford, D.; Ellens, H.; Lis, L.J.; Quinn, P.J.; Yeagle, P.L.; Bentz, J.

    1989-01-01

    In a previous paper, it was shown that liposome fusion rates are substantially enhanced under the same conditions which induce isotropic 31 P NMR resonances in multilamellar dispersions of the same lipid. Both of these phenomena occur within the same temperature interval, ΔT I , below the L α /H II phase transition temperature, T H . T H and ΔT I can be extremely sensitive to the lipid composition. The present work shows that 2 mol % of diacylglycerols like those produced by the phosphatidylinositol cycle in vivo can lower T H , ΔT I , and the temperature for fast membrane fusion by 15-20 degree C. N-Monomethylated dioleoylphosphatidylethanolamine is used as a model system. These results show that physiological levels of diacylglycerols can substantially increase the susceptibility of phospholipid membranes to fusion. This suggests that, in addition to their role in protein kinase C activation, diacylglycerols could play a more direct role in the fusion event during stimulus-exocytosis coupling in vivo

  16. Structure refinement and membrane positioning of selectively labeled OmpX in phospholipid nanodiscs

    Energy Technology Data Exchange (ETDEWEB)

    Hagn, Franz, E-mail: franz.hagn@tum.de; Wagner, Gerhard, E-mail: gerhard-wagner@hms.harvard.edu [Harvard Medical School, Department of Biological Chemistry and Molecular Pharmacology (United States)

    2015-04-15

    NMR structural studies on membrane proteins are often complicated by their large size, taking into account the contribution of the membrane mimetic. Therefore, classical resonance assignment approaches often fail. The large size of phospholipid nanodiscs, a detergent-free phospholipid bilayer mimetic, prevented their use in high-resolution solution-state NMR spectroscopy so far. We recently introduced smaller nanodiscs that are suitable for NMR structure determination. However, side-chain assignments of a membrane protein in nanodiscs still remain elusive. Here, we utilized a NOE-based approach to assign (stereo-) specifically labeled Ile, Leu, Val and Ala methyl labeled and uniformly {sup 15}N-Phe and {sup 15}N-Tyr labeled OmpX and calculated a refined high-resolution structure. In addition, we were able to obtain residual dipolar couplings (RDCs) of OmpX in nanodiscs using Pf1 phage medium for the induction of weak alignment. Back-calculated NOESY spectra of the obtained NMR structures were compared to experimental NOESYs in order to validate the quality of these structures. We further used NOE information between protonated lipid head groups and side-chain methyls to determine the position of OmpX in the phospholipid bilayer. These data were verified by paramagnetic relaxation enhancement (PRE) experiments obtained with Gd{sup 3+}-modified lipids. Taken together, this study emphasizes the need for the (stereo-) specific labeling of membrane proteins in a highly deuterated background for high-resolution structure determination, particularly in large membrane mimicking systems like phospholipid nanodiscs. Structure validation by NOESY back-calculation will be helpful for the structure determination and validation of membrane proteins where NOE assignment is often difficult. The use of protein to lipid NOEs will be beneficial for the positioning of a membrane protein in the lipid bilayer without the need for preparing multiple protein samples.

  17. Mass spectrometric study of rhamnolipid biosurfactants and their interactions with cell membrane phospholipids

    Directory of Open Access Journals (Sweden)

    Pashynska V. A.

    2009-12-01

    Full Text Available Aim. To examine the formation of supramolecular complexes of biogenous rhamnolipids with membrane phospholipids that is considered as a molecular mechanism of the biosurfactants antimicrobial action. Method. In the present work rhamnolipid biosurfactant samples produced by Pseudomonas sp. PS-17 strain have been investigated by electrospray ionization mass spectrometry for the first time. Results. As a result of the study, characteristic mass spectra of the rhamnolipid samples were obtained, that can be used as reference spectra for mass spectrometric identification of the compounds in any biological or industrial samples. At the next stage of the experiments the pair systems, containing the biosurfactants and a membrane phospholipid dipalmitoylphosphatidylcholine, have been tested. The cationized noncovalent complexes of the rhamnolipids with the phospholipid were observed in the spectra. Conclusions. The results obtained testify to the consideration that rhamnolipids (similar to other membranotropic agents can form stable supramolecular complexes with membrane phospholipids that are able to evoke the biosurfactants antimicrobial action. A great potential of electrospray ionization mass spectrometry for the biosurfactants identification and study has been demonstrated in the work.

  18. Field-effect detection using phospholipid membranes -Topical Review

    Directory of Open Access Journals (Sweden)

    Chiho Kataoka-Hamai and Yuji Miyahara

    2010-01-01

    Full Text Available The application of field-effect devices to biosensors has become an area of intense research interest. An attractive feature of field-effect sensing is that the binding or reaction of biomolecules can be directly detected from a change in electrical signals. The integration of such field-effect devices into cell membrane mimics may lead to the development of biosensors useful in clinical and biotechnological applications. This review summarizes recent studies on the fabrication and characterization of field-effect devices incorporating model membranes. The incorporation of black lipid membranes and supported lipid monolayers and bilayers into semiconductor devices is described.

  19. Characterization of Type Three Secretion System Translocator Interactions with Phospholipid Membranes.

    Science.gov (United States)

    Adam, Philip R; Barta, Michael L; Dickenson, Nicholas E

    2017-01-01

    In vitro characterization of type III secretion system (T3SS) translocator proteins has proven challenging due to complex purification schemes and their hydrophobic nature that often requires detergents to provide protein solubility and stability. Here, we provide experimental details for several techniques that overcome these hurdles, allowing for the direct characterization of the Shigella translocator protein IpaB with respect to phospholipid membrane interaction. The techniques specifically discussed in this chapter include membrane interaction/liposome flotation, liposome sensitive fluorescence quenching, and protein-mediated liposome disruption assays. These assays have provided valuable insight into the role of IpaB in T3SS-mediated phospholipid membrane interactions by Shigella and should readily extend to other members of this important class of proteins.

  20. Perforin rapidly induces plasma membrane phospholipid flip-flop.

    Directory of Open Access Journals (Sweden)

    Sunil S Metkar

    Full Text Available The cytotoxic cell granule secretory pathway is essential for host defense. This pathway is fundamentally a form of intracellular protein delivery where granule proteases (granzymes from cytotoxic lymphocytes are thought to diffuse through barrel stave pores generated in the plasma membrane of the target cell by the pore forming protein perforin (PFN and mediate apoptotic as well as additional biological effects. While recent electron microscopy and structural analyses indicate that recombinant PFN oligomerizes to form pores containing 20 monomers (20 nm when applied to liposomal membranes, these pores are not observed by propidium iodide uptake in target cells. Instead, concentrations of human PFN that encourage granzyme-mediated apoptosis are associated with pore structures that unexpectedly favor phosphatidylserine flip-flop measured by Annexin-V and Lactadherin. Efforts that reduce PFN mediated Ca influx in targets did not reduce Annexin-V reactivity. Antigen specific mouse CD8 cells initiate a similar rapid flip-flop in target cells. A lipid that augments plasma membrane curvature as well as cholesterol depletion in target cells enhance flip-flop. Annexin-V staining highly correlated with apoptosis after Granzyme B (GzmB treatment. We propose the structures that PFN oligomers form in the membrane bilayer may include arcs previously observed by electron microscopy and that these unusual structures represent an incomplete mixture of plasma membrane lipid and PFN oligomers that may act as a flexible gateway for GzmB to translocate across the bilayer to the cytosolic leaflet of target cells.

  1. Amphotericin B channels in phospholipid membrane-coated nanoporous silicon surfaces: implications for photovoltaic driving of ions across membranes.

    Science.gov (United States)

    Yilma, Solomon; Liu, Nangou; Samoylov, Alexander; Lo, Ting; Brinker, C Jeffrey; Vodyanoy, Vitaly

    2007-03-15

    The antimycotic agent amphotericin B (AmB) functions by forming complexes with sterols to form ion channels that cause membrane leakage. When AmB and cholesterol mixed at 2:1 ratio were incorporated into phospholipid bilayer membranes formed on the tip of patch pipettes, ion channel current fluctuations with characteristic open and closed states were observed. These channels were also functional in phospholipid membranes formed on nanoporous silicon surfaces. Electrophysiological studies of AmB-cholesterol mixtures that were incorporated into phospholipid membranes formed on the surface of nanoporous (6.5 nm pore diameter) silicon plates revealed large conductance ion channels ( approximately 300 pS) with distinct open and closed states. Currents through the AmB-cholesterol channels on nanoporous silicon surfaces can be driven by voltage applied via conventional electrical circuits or by photovoltaic electrical potential entirely generated when the nanoporous silicon surface is illuminated with a narrow laser beam. Electrical recordings made during laser illumination of AmB-cholesterol containing membrane-coated nanoporous silicon surfaces revealed very large conductance ion channels with distinct open and closed states. Our findings indicate that nanoporous silicon surfaces can serve as mediums for ion-channel-based biosensors. The photovoltaic properties of nanoporous silicon surfaces show great promise for making such biosensors addressable via optical technologies.

  2. Solvent accessible surface area (ASA) of simulated phospholipid membranes

    DEFF Research Database (Denmark)

    Tuchsen, E.; Jensen, Morten Østergaard; Westh, P.

    2003-01-01

    The membrane-solvent interface has been investigated through calculations of the solvent accessible surface area (ASA) for simulated membranes of DPPC and POPE. For DPPC at 52 degreesC we found an ASA of 126 +/- 8 Angstrom(2) per lipid molecule, equivalent to twice the projected lateral area......, even the most exposed parts of the PC head-group show average ASAs of less than half of its maximal or 'fully hydrated' value. The average ASA of a simulated POPE membrane was 96 +/- 7 Angstrom(2) per lipid. The smaller value than for DPPC reflects much lower ASA of the ammonium ion, which is partially...... compensated by increased exposure of the ethylene and phosphate moieties. The ASA of the polar moieties Of (PO4, NH3 and COO) constitutes 65% of the total accessible area for POPE, making this interface more polar than that of DPPC. It is suggested that ASA information can be valuable in attempts...

  3. Interaction of arsenic compounds with model phospholipid membranes

    International Nuclear Information System (INIS)

    Jemiola-Rzeminska, Malgorzata; Rivera, Cecilia; Suwalsky, Mario; Strzalka, Kazimierz

    2007-01-01

    This study is part of a project aimed at examining the influence of arsenic on biological membranes. By the use of differential scanning calorimetry (DSC) we have followed the thermotropic behavior of multilamellar vesicles prepared from dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE) upon incorporation of sodium arsenite (AsI), disodium arsenate (AsII), cacodylic acid (AsIII) and disodium methyl arsenate (AsIV). The effectiveness of perturbations exerted by various arsenic compounds on thermotropic phase transition was further analysed in terms of thermodynamic parameters: transition temperature, enthalpy and molar heat capacity, determined for lipid/As systems on the basis of heating and cooling scans. It is found that while it only has a slight influence on the thermotropic properties of DMPC, arsenic is able to significantly modify DMPE model membranes

  4. Bacillus subtilis alters the proportion of major membrane phospholipids in response to surfactin exposure.

    Science.gov (United States)

    Uttlová, Petra; Pinkas, Dominik; Bechyňková, Olga; Fišer, Radovan; Svobodová, Jaroslava; Seydlová, Gabriela

    2016-12-01

    Surfactin, an anionic lipopeptide produced by Bacillus subtilis, is an antimicrobial that targets the cytoplasmic membrane. Nowadays it appears increasingly apparent that the mechanism of resistance against these types of antibiotics consists of target site modification. This prompted us to investigate whether the surfactin non-producing strain B. subtilis 168 changes its membrane composition in response to a sublethal surfactin concentration. Here we show that the exposure of B. subtilis to surfactin at concentrations of 350 and 650 μg/ml (designated as SF350 and SF650, respectively) leads to a concentration-dependent growth arrest followed by regrowth with an altered growth rate. Analysis of the membrane lipid composition revealed modifications both in the polar head group and the fatty acid region. The presence of either surfactin concentration resulted in a reduction in the content of the major membrane phospholipid phosphatidylglycerol (PG) and increase in phosphatidylethanolamine (PE), which was accompanied by elevated levels of phosphatidic acid (PA) in SF350 cultures. The fatty acid analysis of SF350 cells showed a marked increase in non-branched high-melting fatty acids, which lowered the fluidity of the membrane interior measured as the steady-state fluorescence anisotropy of DPH. The liposome leakage of carboxyfluorescein-loaded vesicles resembling the phospholipid composition of surfactin-adapted cells showed that the susceptibility to surfactin-induced leakage is strongly reduced when the PG/PE ratio decreases and/or PA is included in the target bilayer. We concluded that the modifications of the phospholipid content of B. subtilis cells might provide a self-tolerance of the membrane active surfactin. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Correlated volume-energy fluctuations of phospholipid membranes: A simulation study

    DEFF Research Database (Denmark)

    Pedersen, Ulf. R.; Peters, Günther H.J.; Schröder, Thomas B.

    2010-01-01

    This paper reports all-atom computer simulations of five phospholipid membranes (DMPC, DPPC, DMPG, DMPS, and DMPSH) with focus on the thermal equilibrium fluctuations of volume, energy, area, thickness, and chain order. At constant temperature and pressure, volume and energy exhibit strong...... membranes, showing a similar picture. The cause of the observed strong correlations is identified by splitting volume and energy into contributions from tails, heads, and water, and showing that the slow volume−energy fluctuations derive from van der Waals interactions of the tail region; they are thus...

  6. Covalent attachment of phospholipid analogous polymers to modify a polymeric membrane surface: a novel approach.

    Science.gov (United States)

    Xu, Zhi-Kang; Dai, Qing-Wen; Wu, Jian; Huang, Xiao-Jun; Yang, Qian

    2004-02-17

    A novel method for the surface modification of a microporous polypropylene membrane by tethering phospholipid analogous polymers (PAPs) is given, which includes the photoinduced graft polymerization of N,N-dimethylaminoethyl methacrylate (DMAEMA) and the ring-opening reaction of grafted poly-(DMAEMA) with 2-alkyloxy-2-oxo-1,3,2-dioxaphospholanes. Five 2-alkyloxy-2-oxo-1,3,2-dioxaphospholanes, containing octyloxy, dodecyloxy, tetradecyloxy, hexadecyloxy, and octadecyloxy groups in the molecular structure, were used to fabricate the PAP-modified polypropylene membranes. The attenuated total reflectance FT-IR spectra of the original, poly(DMAEMA)-grafted, and PAP-modified membranes confirmed the chemical changes on the membrane surface. Scanning electron microscope pictures showed that, compared with the original membrane, the surface porosities ofpoly(DMAEMA)-grafted and PAP-modified membranes were somewhat reduced. Water contact angles measured by the sessile drop method on PAP-modified membranes were slightly lower than that on the original polypropylene membrane, but higher than those on poly(DMAEMA)-grafted membranes with the exception of octyloxy-containing PAP-modified membranes. However, BSA adsorption experiments indicated that the five PAP-modified membranes had a much better protein-resistant property than the original polypropylene membrane and the poly(DMAEMA)-grafted membranes. For hexadecyloxy- and octadecyloxy-containing PAP-modified membranes, almost no protein adsorption was observed when the grafting degree was above 6 wt %. It was also found that the platelet adhesion was remarkably suppressed on the PAP-modified membranes. All these results demonstrate that the described approach is an effective way to improve the surface biocompatibility for polymeric membranes.

  7. Perimicrovillar membrane assembly: the fate of phospholipids synthesised by the midgut of Rhodnius prolixus

    Directory of Open Access Journals (Sweden)

    Paula Rego Bittencourt-Cunha

    2013-06-01

    Full Text Available In this study, we describe the fate of fatty acids that are incorporated from the lumen by the posterior midgut epithelium of Rhodnius prolixus and the biosynthesis of lipids. We also demonstrate that neutral lipids (NL are transferred to the haemolymphatic lipophorin (Lp and that phospholipids remain in the tissue in which they are organised into perimicrovillar membranes (PMMs. 3H-palmitic acid added at the luminal side of isolated midguts of R. prolixus females was readily absorbed and was used to synthesise phospholipids (80% and NL (20%. The highest incorporation of 3H-palmitic acid was on the first day after a blood meal. The amounts of diacylglycerol (DG and triacylglycerol synthesised by the tissue decreased in the presence of Lp in the incubation medium. The metabolic fates of 3H-lipids synthesised by the posterior midgut were followed and it was observed that DG was the major lipid released to Lp particles. However, the majority of phospholipids were not transferred to Lp, but remained in the tissue. The phospholipids that were synthesised and accumulated in the posterior midgut were found to be associated with Rhodnius luminal contents as structural components of PMMs.

  8. Bile salt/phospholipid mixed micelle precursor pellets prepared by fluid-bed coating

    Directory of Open Access Journals (Sweden)

    Dong F

    2013-04-01

    Full Text Available Fuxia Dong,1,2 Yunchang Xie,1 Jianping Qi,1 Fuqiang Hu,3 Yi Lu,1 Sanming Li,2 Wei Wu1 1School of Pharmacy, Fudan University, Key Laboratory of Smart Drug Delivery of Ministry of Education and PLA, Shanghai, People’s Republic of China; 2School of Pharmacy, Shenyang Pharmaceutical University, Liaoning, People’s Republic of China; 3School of Pharmacy, Zhejiang University, Hangzhou, People’s Republic of China Abstract: Bile salt/phospholipid mixed micelles (MMs are potent carriers used for oral absorption of drugs that are poorly soluble in water; however, there are many limitations associated with liquid formulations. In the current study, the feasibility of preparing bile salt/phospholipid MM precursor (preMM pellets with high oral bioavailability, using fluid-bed coating technology, was examined. In this study, fenofibrate (FB and sodium deoxycholate (SDC were used as the model drug and the bile salt, respectively. To prepare the MMs and to serve as the micellular carrier, a weight ratio of 4:6 was selected for the sodium deoxycholate/phospholipids based on the ternary phase diagram. Polyethylene glycol (PEG 6000 was selected as the dispersion matrix for precipitation of the MMs onto pellets, since it can enhance the solubilizing ability of the MMs. Coating of the MMs onto the pellets using the fluid-bed coating technology was efficient and the pellets were spherical and intact. MMs could be easily reconstituted from preMM pellets in water. Although they existed in a crystalline state in the preMM pellets, FB could be encapsulated into the reconstituted MMs, and the MMs were redispersed better than solid dispersion pellets (FB:PEG = 1:3 and Lipanthyl®. The redispersibility of the preMM pellets increased with the increase of the FB/PEG/micellar carrier. PreMM pellets with a FB:PEG:micellar carrier ratio of 1:1.5:1.5 showed 284% and 145% bioavailability relative to Lipanthyl® and solid dispersion pellets (FB:PEG = 1:3, respectively. Fluid

  9. Sequestration of polyunsaturated fatty acids in membrane phospholipids of Caenorhabditis elegans dauer larva attenuates eicosanoid biosynthesis for prolonged survival

    Directory of Open Access Journals (Sweden)

    Sin Man Lam

    2017-08-01

    Full Text Available Mechanistic basis governing the extreme longevity and developmental quiescence of dauer juvenile, a “non-ageing” developmental variant of Caenorhabditis elegans, has remained largely obscure. Using a lipidomic approach comprising multiple reaction monitoring transitions specific to distinct fatty acyl moieties, we demonstrated that in comparison to other developmental stages, the membrane phospholipids of dauer larva contain a unique enrichment of polyunsaturated fatty acids (PUFAs. Esterified PUFAs in phospholipids exhibited temporal accumulation throughout the course of dauer endurance, followed by sharp reductions prior to termination of diapause. Reductions in esterified PUFAs were accompanied by concomitant increases in unbound PUFAs, as well as their corresponding downstream oxidized derivatives (i.e. eicosanoids. Global phospholipidomics has unveiled that PUFA sequestration in membrane phospholipids denotes an essential aspect of dauer dormancy, principally via suppression of eicosanoid production; and a failure to upkeep membrane lipid homeostasis is associated with termination of dauer endurance. Keywords: Dauer larva, Phospholipids, Polyunsaturated fatty acids, Eicosanoids, Lipidomics, Caenorhabditis elegans

  10. Parallel artificial liquid membrane extraction as an efficient tool for removal of phospholipids from human plasma.

    Science.gov (United States)

    Ask, Kristine Skoglund; Bardakci, Turgay; Parmer, Marthe Petrine; Halvorsen, Trine Grønhaug; Øiestad, Elisabeth Leere; Pedersen-Bjergaard, Stig; Gjelstad, Astrid

    2016-09-10

    Generic Parallel Artificial Liquid Membrane Extraction (PALME) methods for non-polar basic and non-polar acidic drugs from human plasma were investigated with respect to phospholipid removal. In both cases, extractions in 96-well format were performed from plasma (125μL), through 4μL organic solvent used as supported liquid membranes (SLMs), and into 50μL aqueous acceptor solutions. The acceptor solutions were subsequently analysed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) using in-source fragmentation and monitoring the m/z 184→184 transition for investigation of phosphatidylcholines (PC), sphingomyelins (SM), and lysophosphatidylcholines (Lyso-PC). In both generic methods, no phospholipids were detected in the acceptor solutions. Thus, PALME appeared to be highly efficient for phospholipid removal. To further support this, qualitative (post-column infusion) and quantitative matrix effects were investigated with fluoxetine, fluvoxamine, and quetiapine as model analytes. No signs of matrix effects were observed. Finally, PALME was evaluated for the aforementioned drug substances, and data were in accordance with European Medicines Agency (EMA) guidelines. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Proceedings of the users meeting on structure and phase transition of phospholipid membrane

    International Nuclear Information System (INIS)

    Hatta, Ichiro; Amemiya, Yoshiyuki

    1994-06-01

    On the occasion that the persons of three groups that have carried out the research on the structure and the phase transition of phospholipid membranes have carried out the experiment successively, the users meeting was held on November 1, 1993 at National Laboratory for High Energy Physics. Lectures were given on the L βI structure of DPPC/alcohol system, the self gathering and intermolecular cooperation phenomenon of glycero phospholipid, the phase transition of DEPE/water system, the structure of DMPA/polylysine, the development of X-ray television, the ripple structure of DMPC/cholesterol system and the simultaneous measurement of X-ray diffraction/DSC. To have the chance like this is very meaningful because sufficient discussion can be done among usually busy researchers at the synchrotron radiation experiment facility. (K.I.)

  12. Proceedings of the users meeting on structure and phase transition of phospholipid membrane

    Energy Technology Data Exchange (ETDEWEB)

    Hatta, Ichiro [Nagoya Univ. (Japan). School of Engineering; Amemiya, Yoshiyuki [eds.

    1994-06-01

    On the occasion that the persons of three groups that have carried out the research on the structure and the phase transition of phospholipid membranes have carried out the experiment successively, the users meeting was held on November 1, 1993 at National Laboratory for High Energy Physics. Lectures were given on the L{sub {beta}I} structure of DPPC/alcohol system, the self gathering and intermolecular cooperation phenomenon of glycero phospholipid, the phase transition of DEPE/water system, the structure of DMPA/polylysine, the development of X-ray television, the ripple structure of DMPC/cholesterol system and the simultaneous measurement of X-ray diffraction/DSC. To have the chance like this is very meaningful because sufficient discussion can be done among usually busy researchers at the synchrotron radiation experiment facility. (K.I.).

  13. Role of phospholipids in destabilization of lysosomal membranes in chronic alcohol poisoning

    International Nuclear Information System (INIS)

    Tadevosyan, Y.V.; Batikyan, T.B.; Gevorkyan, G.A.; Karagezyan, K.G.

    1986-01-01

    The aim of this investigation was to study changes in the phospholipids (PL) spectrum and possible activity of membrane-bound phospholipase A 2 in lysosomal membranes from albino rat liver under conditions of the normally metabolizing tissue and during long-term alcohol poisoning. Changes in stability of the lysosomal membranes were determined by measuring nonsedimented acid phosphatase (AP) activity. The substance 1-acyl-2-(1- 14 C)-oleoyl-phosphatidyl-choline ( 14 C-PCh) was synthesized by an enzymic method. Phospholipase A 2 activity was determined in an incubation medium of Tris-Maleate buffer containing 20 nanomoles ( 14 C)-PCH, 8 mM CaC1 2 , and about 100 micrograms protein

  14. A conserved endoplasmic reticulum membrane protein complex (EMC facilitates phospholipid transfer from the ER to mitochondria.

    Directory of Open Access Journals (Sweden)

    Sujoy Lahiri

    2014-10-01

    Full Text Available Mitochondrial membrane biogenesis and lipid metabolism require phospholipid transfer from the endoplasmic reticulum (ER to mitochondria. Transfer is thought to occur at regions of close contact of these organelles and to be nonvesicular, but the mechanism is not known. Here we used a novel genetic screen in S. cerevisiae to identify mutants with defects in lipid exchange between the ER and mitochondria. We show that a strain missing multiple components of the conserved ER membrane protein complex (EMC has decreased phosphatidylserine (PS transfer from the ER to mitochondria. Mitochondria from this strain have significantly reduced levels of PS and its derivative phosphatidylethanolamine (PE. Cells lacking EMC proteins and the ER-mitochondria tethering complex called ERMES (the ER-mitochondria encounter structure are inviable, suggesting that the EMC also functions as a tether. These defects are corrected by expression of an engineered ER-mitochondrial tethering protein that artificially tethers the ER to mitochondria. EMC mutants have a significant reduction in the amount of ER tethered to mitochondria even though ERMES remained intact in these mutants, suggesting that the EMC performs an additional tethering function to ERMES. We find that all Emc proteins interact with the mitochondrial translocase of the outer membrane (TOM complex protein Tom5 and this interaction is important for PS transfer and cell growth, suggesting that the EMC forms a tether by associating with the TOM complex. Together, our findings support that the EMC tethers ER to mitochondria, which is required for phospholipid synthesis and cell growth.

  15. Efficient replacement of plasma membrane outer leaflet phospholipids and sphingolipids in cells with exogenous lipids.

    Science.gov (United States)

    Li, Guangtao; Kim, JiHyun; Huang, Zhen; St Clair, Johnna R; Brown, Deborah A; London, Erwin

    2016-12-06

    Our understanding of membranes and membrane lipid function has lagged far behind that of nucleic acids and proteins, largely because it is difficult to manipulate cellular membrane lipid composition. To help solve this problem, we show that methyl-α-cyclodextrin (MαCD)-catalyzed lipid exchange can be used to maximally replace the sphingolipids and phospholipids in the outer leaflet of the plasma membrane of living mammalian cells with exogenous lipids, including unnatural lipids. In addition, lipid exchange experiments revealed that 70-80% of cell sphingomyelin resided in the plasma membrane outer leaflet; the asymmetry of metabolically active cells was similar to that previously defined for erythrocytes, as judged by outer leaflet lipid composition; and plasma membrane outer leaflet phosphatidylcholine had a significantly lower level of unsaturation than phosphatidylcholine in the remainder of the cell. The data also provided a rough estimate for the total cellular lipids residing in the plasma membrane (about half). In addition to such lipidomics applications, the exchange method should have wide potential for investigations of lipid function and modification of cellular behavior by modification of lipids.

  16. Curcumin liposomes prepared with milk fat globule membrane phospholipids and soybean lecithin.

    Science.gov (United States)

    Jin, Hong-Hao; Lu, Qun; Jiang, Jian-Guo

    2016-03-01

    Using thin film ultrasonic dispersion method, the curcumin liposomes were prepared with milk fat globule membrane (MFGM) phospholipids and soybean lecithins, respectively, to compare the characteristics and stability of the 2 curcumin liposomes. The processing parameters of curcumin liposomes were investigated to evaluate their effects on the encapsulation efficiency. Curcumin liposomes were characterized in terms of size distribution, ζ-potential, and in vitro release behavior, and then their storage stability under various conditions was evaluated. The curcumin liposomes prepared with MFGM phospholipids had an encapsulation efficiency of about 74%, an average particle size of 212.3 nm, and a ζ-potential of -48.60 mV. The MFGM liposomes showed higher encapsulation efficiency, smaller particle size, higher absolute value of ζ-potential, and slower in vitro release than soybean liposomes. The retention rate of liposomal curcumin was significantly higher than that of free curcumin. The stability of the 2 liposomes under different pH was almost the same, but MFGM liposomes displayed a slightly higher stability than soybean liposomes under the conditions of Fe(3+), light, temperature, oxygen, and relative humidity. In conclusion, MFGM phospholipids have potential advantages in the manufacture of curcumin liposomes used in food systems. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  17. [Peculiarities of the phospholipid and fatty acid composition of erythrocyte plasma membranes of the Black Sea fish].

    Science.gov (United States)

    Silkin, Iu A; Silkina, E N; Zabelinskiĭ, S A

    2012-01-01

    The phospholipid and the fatty acid composition of the main phospholipids families of erythrocyte plasma membranes was studied in two species of cartilaginous fish: the common thrasher (Raja clavata L.) and the common stingray (Dasyatis pastinaca) and three bony fish species: the scorpion fish (Scorpaena porcus L.), the smarida (Spicara flexuosa Raf.), and the horse mackerel (Trachurus mediterraneus ponticus Aleev). It was shown that in the studied fish, 70.0-80.0 % of all membrane phospholipids were composed of phosphatidylcholine and phosphatidylethanolamine. Phosphatidylserine, monophosphoinositide, and sphingomyelin were minor components whose content in the erythrocyte membrane fluctuated from 3.0 % to 13.0 %. The fatty acid phospholipids composition was represented by a large specter of acids. From saturated acids, basic for plasma membranes are palmitic (C16: 0) and stearic (C18: 0) acids. From unsaturated acids, the larger part belong to mono-, tetra-, penta-, and hexaenoic acids in fish phospholipids. The calculation of the double bond index and of the unsaturation coefficient showed difference in the deformation ability of erythrocyte membranes of the studied fish.

  18. Supercritical CO2 induces marked changes in membrane phospholipids composition in Escherichia coli K12.

    Science.gov (United States)

    Tamburini, Sabrina; Anesi, Andrea; Ferrentino, Giovanna; Spilimbergo, Sara; Guella, Graziano; Jousson, Olivier

    2014-06-01

    Supercritical carbon dioxide (SC-CO2) treatment is one of the most promising alternative techniques for pasteurization of both liquid and solid food products. The inhibitory effect of SC-CO2 on bacterial growth has been investigated in different species, but the precise mechanism of action remains unknown. Membrane permeabilization has been proposed to be the first event in SC-CO2-mediated inactivation. Flow cytometry, high performance liquid chromatography–electrospray ionization–mass spectrometry and NMR analyses were performed to investigate the effect of SC-CO2 treatment on membrane lipid profile and membrane permeability in Escherichia coli K12. After 15 min of SC-CO2 treatment at 120 bar and 35 °C, the majority of bacterial cells dissipated their membrane potential (95 %) and lost membrane integrity, as 81 % become partially permeabilized and 18 % fully permeabilized. Membrane permeabilization was associated with a 20 % decrease in bacterial biovolume and to a strong (>50 %) reduction in phosphatidylglycerol (PG) membrane lipids, without altering the fatty acid composition and the degree of unsaturation of acyl chains. PGs are thought to play an important role in membrane stability, by reducing motion of phosphatidylethanolamine (PE) along the membrane bilayer, therefore promoting the formation of inter-lipid hydrogen bonds. In addition, the decrease in intracellular pH induced by SC-CO2 likely alters the chemical properties of phospholipids and the PE/PG ratio. Biophysical effects of SC-CO2 thus cause a strong perturbation of membrane architecture in E. coli, and such alterations are likely associated with its strong inactivation effect.

  19. Bile Salt Micelles and Phospholipid Vesicles Present in Simulated and Human Intestinal Fluids

    DEFF Research Database (Denmark)

    Elvang, Philipp A; Hinna, Askell H; Brouwers, Joachim

    2016-01-01

    Knowledge about colloidal assemblies present in human intestinal fluids (HIFs), such as bile salt micelles and phospholipid vesicles, is regarded of importance for a better understanding of the in vivo dissolution and absorption behavior of poorly soluble drugs (Biopharmaceutics Classification...... System class II/IV drugs) because of their drug-solubilizing ability. The characterization of these potential drug-solubilizing compartments is a prerequisite for further studies of the mechanistic interplays between drug molecules and colloidal structures within HIFs. The aim of the present study...... and HIF indicate that the simulated intestinal fluids (FaSSIF-V1 and FeSSIF-V1) represent rather simplified models of the real human intestinal environment in terms of coexisting colloidal particles. It is hypothesized that the different supramolecular assemblies detected differ in their lipid composition...

  20. Temperature-induced changes in lecithin model membranes detected by novel covalent spin-labelled phospholipids.

    Science.gov (United States)

    Stuhne-Sekalec, L; Stanacev, N Z

    1977-02-01

    Several spin-labelled phospholipids carrying covalently bound 5-doxylstearic acid (2-(3-carboxydecyl)-2-hexyl-4,4-dimethyl-3-oxazolidinoxyl) were intercalated in liposomes of saturated and unsaturated lecithins. Temperature-induced changes of these liposomes, detected by the spin-labelled phospholipids, were found to be in agreement with the previously described transitions of hydrocarbon chains of host lecithins detected by different probes and different techniques, establishing that spin-labelled phosopholipids are sensitive probes for the detection of temperature-induced changes in lecithin model membranes. In addition to the detection of already-known transitions in lecithin liposomes, the coexistence of two distinctly different enviroments was observed above the characteristic transition temperature. This phenomenon was tentatively attributed to the influence of the lecithin polar group on the fluidity of fatty acyl chains near the polar group. Combined with other results from the literature, the coexistence of two environments could be associated with the coexistence of two conformational isomers of lecithin, differing in the orientation of the polar head group with respect to the plane of bilayer. These findings have been discussed in view of the present state of knowledge regarding temperature-induced changes in model membranes.

  1. Plasma and erythrocyte membrane phospholipids and fatty acids in Italian general population and hemodialysis patients.

    Science.gov (United States)

    Dessì, Mariarita; Noce, Annalisa; Bertucci, Pierfrancesco; Noce, Gianluca; Rizza, Stefano; De Stefano, Alessandro; Manca di Villahermosa, Simone; Bernardini, Sergio; De Lorenzo, Antonino; Di Daniele, Nicola

    2014-03-21

    Dyslipidemia and abnormal phospholipid metabolism are frequent in uremic patients and increase their risk of cardiovascular disease (CVD): ω-3 polyunsaturated fatty acids (PUFAs) may reduce this risk in the general population. In this study we compared the plasma and erythrocyte cell membrane composition of PUFAs in a group of Caucasian hemodialysis (HD) patients and in a control group of healthy subjects and evaluated the erythrocyte/cell membrane fatty acid ratio as a marker of the dietary intake of phospholipids. The relationship between ω-3 and ω-6 fatty acids and the possible differences in PUFAs concentrations were also investigated. After obtaining a fully informed consent, a total of ninety-nine HD patients and 160 non uremic control subjects from "Tor Vergata" University Hospital were enrolled into the study. None of them took antioxidant drugs or dietary supplements for at least 90 days prior to the observation. Blood samples were analysed by gas-chromatographic coupled to a mass spectrometric detector.The daily intake of total calories, proteins, lipids and carbohydrates is significantly lower in HD patients than in controls (p HD patients (p HD patients, due to the removal of nutrients during the dialysis and to persistent malnutrition. A dietary treatment addressed to increase plasma ω-3 PUFAs and to optimize ω-6/ω-3 ratio may exert a protective action and reduce the risk of CVD in HD patient.

  2. Characterization of Hydrophobic Interactions of Polymers with Water and Phospholipid Membranes Using Molecular Dynamics Simulations

    Science.gov (United States)

    Drenscko, Mihaela

    small membranes using all atomistic and coarse-grained methods. The molecular interaction between common polymer chains used in biomedical applications and the cell membrane is unknown. This interaction may affect the biocompatibility of the polymer chains. Molecular dynamics simulations offer an emerging tool to characterize the interaction between common degradable polymer chains used in biomedical applications, such as polycaprolactone, and model cell membranes. We systematically characterize with long-time all-atomistic molecular dynamics simulations the interaction between single polycaprolactone chains of varying chain lengths with a model phospholipid membrane. We find that the length of polymer chain greatly affects the nature of interaction with the membrane, as well as the membrane properties. Furthermore, we next utilize advanced sampling techniques in molecular dynamics to characterize the two-dimensional free energy surface for the interaction of varying polymer chain lengths (short, intermediate, and long) with model cell membranes. We find that the free energy minimum shifts from the membrane-water interface to the hydrophobic core of the phospholipid membrane as a function of chain length. These results can be used to design polymer chain lengths and chemistries to optimize their interaction with cell membranes at the molecular level.

  3. Mitochondrial cardiolipin/phospholipid trafficking: the role of membrane contact site complexes and lipid transfer proteins.

    Science.gov (United States)

    Schlattner, Uwe; Tokarska-Schlattner, Malgorzata; Rousseau, Denis; Boissan, Mathieu; Mannella, Carmen; Epand, Richard; Lacombe, Marie-Lise

    2014-04-01

    Historically, cellular trafficking of lipids has received much less attention than protein trafficking, mostly because its biological importance was underestimated, involved sorting and translocation mechanisms were not known, and analytical tools were limiting. This has changed during the last decade, and we discuss here some progress made in respect to mitochondria and the trafficking of phospholipids, in particular cardiolipin. Different membrane contact site or junction complexes and putative lipid transfer proteins for intra- and intermembrane lipid translocation have been described, involving mitochondrial inner and outer membrane, and the adjacent membranes of the endoplasmic reticulum. An image emerges how cardiolipin precursors, remodeling intermediates, mature cardiolipin and its oxidation products could migrate between membranes, and how this trafficking is involved in cardiolipin biosynthesis and cell signaling events. Particular emphasis in this review is given to mitochondrial nucleoside diphosphate kinase D and mitochondrial creatine kinases, which emerge to have roles in both, membrane junction formation and lipid transfer. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  4. Aqueous magnesium as an environmental selection pressure in the evolution of phospholipid membranes on early earth

    Science.gov (United States)

    Dalai, Punam; Ustriyana, Putu; Sahai, Nita

    2018-02-01

    Early compartmentalization of simple biomolecules by membrane bilayers was, presumably, a critical step in the emergence of the first cell-like entities, protocells. Their membranes were likely composed of single chain amphiphiles (SCAs), but pure SCA membranes especially those with short-chains are highly unstable towards divalent cations, which are ubiquitous in aqueous environments. The prebiotic synthesis of phospholipids (PLs), even in only trace amounts, may also have been possible. PL membranes are much more stable towards divalent cations. Here, we show the transition of fatty acid membranes to mixed fatty acid-PL and, finally, to PL membranes in the presence of Mg2+, which acts as an environmental selection pressure, and we propose different mechanisms for the observed increased Mg2+-immunity. The "fatal" concentration ([Mg2+]fatal) at which vesicles are disrupted increased dramatically by an order of magnitude from OA to mixed to POPC vesicles. Two mechanisms for the increasing immunity were determined. The negative charge density of the vesicles decreased with increasing POPC content, so more Mg2+ was required for disruption. More interestingly, Mg2+ preferentially bound to and abstracted OA from mixed lipid membranes, resulting in relatively POPC-enriched vesicles compared to the initial ratio. The effect was the most dramatic for the largest initial OA-POPC ratio representing the most primitive protocells. Thus, Mg2+ acted to evolve the mixed membrane composition towards PL enrichment. To the best of our knowledge, this is the first report of selective lipid abstraction from mixed SCA-PL vesicles. These results may hold implications for accommodating prebiotic Mg2+-promoted processes such as non-enzymatic RNA polymerization on early Earth.

  5. Phospholipid composition and a polybasic motif determine D6 PROTEIN KINASE polar association with the plasma membrane and tropic responses.

    Science.gov (United States)

    Barbosa, Inês C R; Shikata, Hiromasa; Zourelidou, Melina; Heilmann, Mareike; Heilmann, Ingo; Schwechheimer, Claus

    2016-12-15

    Polar transport of the phytohormone auxin through PIN-FORMED (PIN) auxin efflux carriers is essential for the spatiotemporal control of plant development. The Arabidopsis thaliana serine/threonine kinase D6 PROTEIN KINASE (D6PK) is polarly localized at the plasma membrane of many cells where it colocalizes with PINs and activates PIN-mediated auxin efflux. Here, we show that the association of D6PK with the basal plasma membrane and PINs is dependent on the phospholipid composition of the plasma membrane as well as on the phosphatidylinositol phosphate 5-kinases PIP5K1 and PIP5K2 in epidermis cells of the primary root. We further show that D6PK directly binds polyacidic phospholipids through a polybasic lysine-rich motif in the middle domain of the kinase. The lysine-rich motif is required for proper PIN3 phosphorylation and for auxin transport-dependent tropic growth. Polybasic motifs are also present at a conserved position in other D6PK-related kinases and required for membrane and phospholipid binding. Thus, phospholipid-dependent recruitment to membranes through polybasic motifs might not only be required for D6PK-mediated auxin transport but also other processes regulated by these, as yet, functionally uncharacterized kinases. © 2016. Published by The Company of Biologists Ltd.

  6. Immobilized fluid membranes for gas separation

    Science.gov (United States)

    Liu, Wei; Canfield, Nathan L; Zhang, Jian; Li, Xiaohong Shari; Zhang, Jiguang

    2014-03-18

    Provided herein are immobilized liquid membranes for gas separation, methods of preparing such membranes and uses thereof. In one example, the immobilized membrane includes a porous metallic host matrix and an immobilized liquid fluid (such as a silicone oil) that is immobilized within one or more pores included within the porous metallic host matrix. The immobilized liquid membrane is capable of selective permeation of one type of molecule (such as oxygen) over another type of molecule (such as water). In some examples, the selective membrane is incorporated into a device to supply oxygen from ambient air to the device for electrochemical reactions, and at the same time, to block water penetration and electrolyte loss from the device.

  7. Modeling of mass transfer of Phospholipids in separation process with supercritical CO2 fluid by RBF artificial neural networks

    Science.gov (United States)

    An artificial Radial Basis Function (RBF) neural network model was developed for the prediction of mass transfer of the phospholipids from canola meal in supercritical CO2 fluid. The RBF kind of artificial neural networks (ANN) with orthogonal least squares (OLS) learning algorithm were used for mod...

  8. Eccentric contractions affect muscle membrane phospholipid fatty acid composition in rats

    DEFF Research Database (Denmark)

    Helge, Jørn Wulff; Therkildsen, K J; Jørgensen, T B

    2001-01-01

    This study investigated if prior eccentric contractions, and thus mechanical strain and muscle damage, exert an effect on the muscle membrane phospholipid fatty acid composition in rats, and whether a possible effect could be attenuated by dietary supplements. Twenty-three rats were randomised...... muscle, was excised from both legs. In the muscles stimulated to contract eccentrically, compared to the control muscles, the proportion of arachidonic acid, C20:4,n-6 (17.7 +/- 0.6; 16.4 +/- 0.4% of total fatty acids, respectively) and docosapentanoeic acid, C22:5,n-3 (2.9 +/- 0.1 and 2.7 +/- 0.......1% of total fatty acids, respectively) was uniformly higher across groups (P fatty acids) compared to the control leg (38.2 +/- 0...

  9. Effects of acclimation temperature on thermal tolerance and membrane phospholipid composition in the fruit fly Drosophila melanogaster

    Czech Academy of Sciences Publication Activity Database

    Overgaard, J.; Tomčala, Aleš; Sorensen, J. G.; Holmstrup, M.; Krogh, P. H.; Šimek, Petr; Košťál, Vladimír

    2008-01-01

    Roč. 54, č. 3 (2008), s. 619-629 ISSN 0022-1910 R&D Projects: GA ČR GA206/07/0269 Institutional research plan: CEZ:AV0Z50070508 Keywords : homeoviscous adaptation * membrane phospholipid * PE Subject RIV: ED - Physiology Impact factor: 2.155, year: 2008

  10. Daptomycin resistance in enterococci is associated with distinct alterations of cell membrane phospholipid content.

    Directory of Open Access Journals (Sweden)

    Nagendra N Mishra

    Full Text Available The lipopeptide antibiotic, daptomycin (DAP interacts with the bacterial cell membrane (CM. Development of DAP resistance during therapy in a clinical strain of Enterococcus faecalis was associated with mutations in genes encoding enzymes involved in cell envelope homeostasis and phospholipid metabolism. Here we characterized changes in CM phospholipid profiles associated with development of DAP resistance in clinical enterococcal strains.Using two clinical strain-pairs of DAP-susceptible and DAP-resistant E. faecalis (S613 vs. R712 and E. faecium (S447 vs. R446 recovered before and after DAP therapy, we compared four distinct CM profiles: phospholipid content, fatty acid composition, membrane fluidity and capacity to be permeabilized and/or depolarized by DAP. Additionally, we characterized the cell envelope of the E. faecium strain-pair by transmission electron microscopy and determined the relative cell surface charge of both strain-pairs.Both E. faecalis and E. faecium mainly contained four major CM PLs: phosphatidylglycerol (PG, cardiolipin, lysyl-phosphatidylglycerol (L-PG and glycerolphospho-diglycodiacylglycerol (GP-DGDAG. In addition, E. faecalis CMs (but not E. faecium also contained: i phosphatidic acid; and ii two other unknown species of amino-containing PLs. Development of DAP resistance in both enterococcal species was associated with a significant decrease in CM fluidity and PG content, with a concomitant increase in GP-DGDAG. The strain-pairs did not differ in their outer CM translocation (flipping of amino-containing PLs. Fatty acid content did not change in the E. faecalis strain-pair, whereas a significant decrease in unsaturated fatty acids was observed in the DAP-resistant E. faecium isolate R446 (vs S447. Resistance to DAP in E. faecium was associated with distinct structural alterations of the cell envelope and cell wall thickening, as well as a decreased ability of DAP to depolarize and permeabilize the CM

  11. Analysis of the induction of the myelin basic protein binding to the plasma membrane phospholipid monolayer

    International Nuclear Information System (INIS)

    Zhang Lei; Hao Changchun; Feng Ying; Gao Feng; Lu Xiaolong; Li Junhua; Sun Runguang

    2016-01-01

    Myelin basic protein (MBP) is an essential structure involved in the generation of central nervous system (CNS) myelin. Myelin shape has been described as liquid crystal structure of biological membrane. The interactions of MBP with monolayers of different lipid compositions are responsible for the multi-lamellar structure and stability of myelin. In this paper, we have designed MBP-incorporated model lipid monolayers and studied the phase behavior of MBP adsorbed on the plasma membrane at the air/water interface by thermodynamic method and atomic force microscopy (AFM). By analyzing the pressure–area ( π – A ) and pressure–time ( π – T ) isotherms, univariate linear regression equation was obtained. In addition, the elastic modulus, surface pressure increase, maximal insertion pressure, and synergy factor of monolayers were detected. These parameters can be used to modulate the monolayers binding of protein, and the results show that MBP has the strongest affinity for 1,2-dipalmitoyl-sn-glycero-3- phosphoserine (DPPS) monolayer, followed by DPPC/DPPS mixed and 1,2-dipalmitoyl-sn-glycero-3-phospho-choline (DPPC) monolayers via electrostatic and hydrophobic interactions. AFM images of DPPS and DPPC/DPPS mixed monolayers in the presence of MBP (5 nM) show a phase separation texture at the surface pressure of 20 mN/m and the incorporation of MBP put into the DPPC monolayers has exerted a significant effect on the domain structure. MBP is not an integral membrane protein but, due to its positive charge, interacts with the lipid head groups and stabilizes the membranes. The interaction between MBP and phospholipid membrane to determine the nervous system of the disease has a good biophysical significance and medical value. (special topic)

  12. Pulmonary phospholipids in amniotic fluid of pathologic pregnancies: relationship with clinical status of the newborn.

    Science.gov (United States)

    Zapata, A; Hernandez-Garcia, J M; Grande, C; Martinez, I; Perez, J; de la Fuente, P; Usandizaga, J A

    1989-06-01

    We evaluated phospholipids, C-peptide and cortisol levels in amniotic fluid of 203 pathologic pregnancies (63, class A, B and C diabetics; 11 class D, F and H diabetics; 44 preclampsia and 85 Rh-isoimmunization); the control group was 82 normal pregnant women. There was an acceleration of fetal pulmonary maturation in women with preclampsia and severe Rh-isoimmunization in class D, F and H diabetics (at 34 weeks gestation the incidence of mature surfactant (lecithin/sphingomyelin greater than or equal to 2.7 and presence of phosphatidyl-glycerol) in these groups was 30%, 50% and 100%, respectively, while it was zero in the control group). At 37 and 38 weeks only 44.4% of the class A, B and C diabetics had mature surfactant and there was a significant difference with respect to the control group (x2 = 4.9; p less than 0.05); C-peptide levels in these diabetics (class A, B and C) were higher than in controls (p less than 0.001); in pregnant women with accelerated fetal lung maturation they were lower. We demonstrated a close relationship between fetal pulmonary maturity and the type of surfactant in amniotic fluid, which was independent of gestational age.

  13. Improved mitochondrial function with diet-induced increase in either docosahexaenoic acid or arachidonic acid in membrane phospholipids.

    Directory of Open Access Journals (Sweden)

    Ramzi J Khairallah

    Full Text Available Mitochondria can depolarize and trigger cell death through the opening of the mitochondrial permeability transition pore (MPTP. We recently showed that an increase in the long chain n3 polyunsaturated fatty acids (PUFA docosahexaenoic acid (DHA; 22:6n3 and depletion of the n6 PUFA arachidonic acid (ARA; 20:4n6 in mitochondrial membranes is associated with a greater Ca(2+ load required to induce MPTP opening. Here we manipulated mitochondrial phospholipid composition by supplementing the diet with DHA, ARA or combined DHA+ARA in rats for 10 weeks. There were no effects on cardiac function, or respiration of isolated mitochondria. Analysis of mitochondrial phospholipids showed DHA supplementation increased DHA and displaced ARA in mitochondrial membranes, while supplementation with ARA or DHA+ARA increased ARA and depleted linoleic acid (18:2n6. Phospholipid analysis revealed a similar pattern, particularly in cardiolipin. Tetralinoleoyl cardiolipin was depleted by 80% with ARA or DHA+ARA supplementation, with linoleic acid side chains replaced by ARA. Both the DHA and ARA groups had delayed Ca(2+-induced MPTP opening, but the DHA+ARA group was similar to the control diet. In conclusion, alterations in mitochondria membrane phospholipid fatty acid composition caused by dietary DHA or ARA was associated with a greater cumulative Ca(2+ load required to induced MPTP opening. Further, high levels of tetralinoleoyl cardiolipin were not essential for normal mitochondrial function if replaced with very-long chain n3 or n6 PUFAs.

  14. Binding of the radioprotective agent cysteamine with the phospholipidic membrane headgroup-interface region

    Energy Technology Data Exchange (ETDEWEB)

    Berleur, F; Roman, V; Jaskierowicz, D; Fatome, M; Leterrier, F; Ter-Minassian-Saraga, L; Madelmont, G

    1985-09-01

    The interaction of the aminothiol radioprotector cysteamine (..beta..-mercaptoethylamine)(CYST) with dipalmitoylphosphatidylcholine (DPPC) artificial membranes has been studied by differential scanning calorimetry (DSC), turbidimetry and spin labeling. This hydrophilic molecule displays a biphasic, concentration-dependent binding to the phospholipidic head groups at neutral pH. In the CYST/DPPC molar ratio 1:160-1:2 (mole/mole) an increasing ordering effect is observed. At high concentrations (over 3:1 ratio), this ordering effect decreases. With the symmetric disulfide dimer cystamine, the biphasic effect is not shown and the membrane rigidity decrease is obtained only at concentration ratio higher than 1:1. The charge repartition of the cysteamine molecule has been shown to be disymmetric, +0.52 e on the NH/sub 3/ group and +0.19 e on the SH extremity, whereas the cystamine molecule is electrostatically symmetrical. These properties could be related to their membrane effects. With cysteamine, at a low concentration, an electrostatic bridging between the negatively charged phosphate groups of the polar heads induces the increase in membrane stability: the molecules behave like a divalent cation. At high concentration a displacement of the slightly charged SH extremity by the amine disrupts the bridges and induces the decrease in rigidity: the drug behaves like a monovalent cation. Due to its symmetric charge and its double length, such an effect is not observed with cystamine. This study could bring further information about the interactions between cysteamine and polyelectrolytic structures (ADN for example) and about the radioprotective properties of this drug.

  15. Kinase Associated-1 Domains Drive MARK/PAR1 Kinases to Membrane Targets by Binding Acidic Phospholipids

    Energy Technology Data Exchange (ETDEWEB)

    Moravcevic, Katarina; Mendrola, Jeannine M.; Schmitz, Karl R.; Wang, Yu-Hsiu; Slochower, David; Janmey, Paul A.; Lemmon, Mark A. (UPENN-MED)

    2011-09-28

    Phospholipid-binding modules such as PH, C1, and C2 domains play crucial roles in location-dependent regulation of many protein kinases. Here, we identify the KA1 domain (kinase associated-1 domain), found at the C terminus of yeast septin-associated kinases (Kcc4p, Gin4p, and Hsl1p) and human MARK/PAR1 kinases, as a membrane association domain that binds acidic phospholipids. Membrane localization of isolated KA1 domains depends on phosphatidylserine. Using X-ray crystallography, we identified a structurally conserved binding site for anionic phospholipids in KA1 domains from Kcc4p and MARK1. Mutating this site impairs membrane association of both KA1 domains and intact proteins and reveals the importance of phosphatidylserine for bud neck localization of yeast Kcc4p. Our data suggest that KA1 domains contribute to coincidence detection, allowing kinases to bind other regulators (such as septins) only at the membrane surface. These findings have important implications for understanding MARK/PAR1 kinases, which are implicated in Alzheimer's disease, cancer, and autism.

  16. Fuel cell membrane hydration and fluid metering

    Science.gov (United States)

    Jones, Daniel O.; Walsh, Michael M.

    1999-01-01

    A hydration system includes fuel cell fluid flow plate(s) and injection port(s). Each plate has flow channel(s) with respective inlet(s) for receiving respective portion(s) of a given stream of reactant fluid for a fuel cell. Each injection port injects a portion of liquid water directly into its respective flow channel in order to mix its respective portion of liquid water with the corresponding portion of the stream. This serves to hydrate at least corresponding part(s) of a given membrane of the corresponding fuel cell(s). The hydration system may be augmented by a metering system including flow regulator(s). Each flow regulator meters an injecting at inlet(s) of each plate of respective portions of liquid into respective portion(s) of a given stream of fluid by corresponding injection port(s).

  17. Analysis of the induction of the myelin basic protein binding to the plasma membrane phospholipid monolayer

    Science.gov (United States)

    Zhang, Lei; Hao, Changchun; Feng, Ying; Gao, Feng; Lu, Xiaolong; Li, Junhua; Sun, Runguang

    2016-09-01

    Myelin basic protein (MBP) is an essential structure involved in the generation of central nervous system (CNS) myelin. Myelin shape has been described as liquid crystal structure of biological membrane. The interactions of MBP with monolayers of different lipid compositions are responsible for the multi-lamellar structure and stability of myelin. In this paper, we have designed MBP-incorporated model lipid monolayers and studied the phase behavior of MBP adsorbed on the plasma membrane at the air/water interface by thermodynamic method and atomic force microscopy (AFM). By analyzing the pressure-area (π-A) and pressure-time (π-T) isotherms, univariate linear regression equation was obtained. In addition, the elastic modulus, surface pressure increase, maximal insertion pressure, and synergy factor of monolayers were detected. These parameters can be used to modulate the monolayers binding of protein, and the results show that MBP has the strongest affinity for 1,2-dipalmitoyl-sn-glycero-3- phosphoserine (DPPS) monolayer, followed by DPPC/DPPS mixed and 1,2-dipalmitoyl-sn-glycero-3-phospho-choline (DPPC) monolayers via electrostatic and hydrophobic interactions. AFM images of DPPS and DPPC/DPPS mixed monolayers in the presence of MBP (5 nM) show a phase separation texture at the surface pressure of 20 mN/m and the incorporation of MBP put into the DPPC monolayers has exerted a significant effect on the domain structure. MBP is not an integral membrane protein but, due to its positive charge, interacts with the lipid head groups and stabilizes the membranes. The interaction between MBP and phospholipid membrane to determine the nervous system of the disease has a good biophysical significance and medical value. Project supported by the National Natural Science Foundation of China (Grant Nos. 21402114 and 11544009), the Natural Science Basic Research Plan in Shaanxi Province of China (Grant No. 2016JM2010), the Fundamental Research Funds for the Central

  18. Effects of Chain Length and Saturability of Fatty Acids on Phospholipids and Proteins in Plasma Membranes of Bovine Mammary Gland.

    Science.gov (United States)

    Yan, Qiongxian; Tang, Shaoxun; Han, Xuefeng; Bamikole, Musibau Adungbe; Zhou, Chuanshe; Kang, Jinhe; Wang, Min; Tan, Zhiliang

    2016-12-01

    Free fatty acids (FFAs) in plasma are essential substrates for de novo synthesis of milk fat, or directly import into mammary cells. The physico-chemical properties of mammary cells membrane composition affected by FFAs with different chain lengths and saturability are unclear yet. Employing GC, FTIR and fluorescence spectroscopy, the adsorption capacity, phospholipids content, membrane proteins conformation, lipid peroxidation product, and free sulfhydryl of plasma membranes (PMs) interacted with different FFAs were determined. The mammary cells PMs at 38 and 39.5 °C showed different adsorption capacities: acetic acid (Ac) > stearic acid (SA) > β-hydroxybutyric acid (BHBA) > trans10, cis12 CLA. In the FTIR spectrum, the major adsorption peaks appeared at 2920 and 2850 cm -1 for phospholipids, and at 1628 and 1560 cm -1 for membrane proteins. The intensities of PMs-FFAs complexes were varied with the FFAs species and their initial concentrations. The β-sheet and turn structures of membrane proteins were transferred into random coil and α-helix after BHBA, SA and trans10, cis12 CLA treatments compared with Ac treatment. The quenching effects on the fluorescence of endogenous membrane protein, 1, 8-ANS, NBD-PE, and DHPE entrapped in PMs by LCFA were different from those of short chain FFAs. These results indicate that the adsorption of FFAs could change membrane protein conformation and polarity of head group in phospholipids. This variation of the mammary cells PMs was regulated by carbon chain length and saturability of FFAs.

  19. Lipophilic organic pollutants induce changes in phospholipid and membrane protein composition leading to Vero cell morphological change.

    Science.gov (United States)

    Liao, Ting T; Wang, Lei; Jia, Ru W; Fu, Xiao H; Chua, Hong

    2014-01-01

    Membrane damage related to morphological change in Vero cells is a sensitive index of the composite biotoxicity of trace lipophilic chemicals. However, judging whether the morphological change in Vero cells happens and its ratio are difficult because it is not a quantitative characteristic. To find biomarkers of cell morphological change for quantitatively representing the ratio of morphological changed cell, the mechanism of cell membrane damage driven by typical lipophilic chemicals, such as trichlorophenol (TCP) and perfluorooctanesulphonate (PFOS), was explored. The ratio of morphologically changed cells generally increased with increased TCP or PFOS concentrations, and the level of four major components of phospholipids varied with concentrations of TCP or PFOS, but only the ratio of phosphatidylcholine (PC)/phosphatidylethanolamine (PE) decreased regularly as TCP or PFOS concentrations increased. Analysis of membrane proteins showed that the level of vimentin in normal cell membranes is high, while it decreases or vanishes after TCP exposure. These variations in phospholipid and membrane protein components may result in membrane leakage and variation in rigid structure, which leads to changes in cell morphology. Therefore, the ratio of PC/PE and amount of vimentin may be potential biomarkers for representing the ratio of morphological changed Vero cell introduced by trace lipophilic compounds, thus their composite bio-toxicity.

  20. Yeast PAH1-encoded phosphatidate phosphatase controls the expression of CHO1-encoded phosphatidylserine synthase for membrane phospholipid synthesis.

    Science.gov (United States)

    Han, Gil-Soo; Carman, George M

    2017-08-11

    The PAH1 -encoded phosphatidate phosphatase (PAP), which catalyzes the committed step for the synthesis of triacylglycerol in Saccharomyces cerevisiae , exerts a negative regulatory effect on the level of phosphatidate used for the de novo synthesis of membrane phospholipids. This raises the question whether PAP thereby affects the expression and activity of enzymes involved in phospholipid synthesis. Here, we examined the PAP-mediated regulation of CHO1 -encoded phosphatidylserine synthase (PSS), which catalyzes the committed step for the synthesis of major phospholipids via the CDP-diacylglycerol pathway. The lack of PAP in the pah1 Δ mutant highly elevated PSS activity, exhibiting a growth-dependent up-regulation from the exponential to the stationary phase of growth. Immunoblot analysis showed that the elevation of PSS activity results from an increase in the level of the enzyme encoded by CHO1 Truncation analysis and site-directed mutagenesis of the CHO1 promoter indicated that Cho1 expression in the pah1 Δ mutant is induced through the inositol-sensitive upstream activation sequence (UAS INO ), a cis -acting element for the phosphatidate-controlled Henry (Ino2-Ino4/Opi1) regulatory circuit. The abrogation of Cho1 induction and PSS activity by a CHO1 UAS INO mutation suppressed pah1 Δ effects on lipid synthesis, nuclear/endoplasmic reticulum membrane morphology, and lipid droplet formation, but not on growth at elevated temperature. Loss of the DGK1 -encoded diacylglycerol kinase, which converts diacylglycerol to phosphatidate, partially suppressed the pah1 Δ-mediated induction of Cho1 and PSS activity. Collectively, these data showed that PAP activity controls the expression of PSS for membrane phospholipid synthesis. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  1. Two-component fluid membranes near repulsive walls: Linearized hydrodynamics of equilibrium and nonequilibrium states.

    Science.gov (United States)

    Sankararaman, Sumithra; Menon, Gautam I; Sunil Kumar, P B

    2002-09-01

    We study the linearized hydrodynamics of a two-component fluid membrane near a repulsive wall, using a model that incorporates curvature-concentration coupling as well as hydrodynamic interactions. This model is a simplified version of a recently proposed one [J.-B. Manneville et al., Phys. Rev. E 64, 021908 (2001)] for nonequilibrium force centers embedded in fluid membranes, such as light-activated bacteriorhodopsin pumps incorporated in phospholipid egg phosphatidyl choline (EPC) bilayers. The pump-membrane system is modeled as an impermeable, two-component bilayer fluid membrane in the presence of an ambient solvent, in which one component, representing active pumps, is described in terms of force dipoles displaced with respect to the bilayer midpoint. We first discuss the case in which such pumps are rendered inactive, computing the mode structure in the bulk as well as the modification of hydrodynamic properties by the presence of a nearby wall. These results should apply, more generally, to equilibrium fluid membranes comprised of two components, in which the effects of curvature-concentration coupling are significant, above the threshold for phase separation. We then discuss the fluctuations and mode structure in the steady state of active two-component membranes near a repulsive wall. We find that proximity to the wall smoothens membrane height fluctuations in the stable regime, resulting in a logarithmic scaling of the roughness even for initially tensionless membranes. This explicitly nonequilibrium result is a consequence of the incorporation of curvature-concentration coupling in our hydrodynamic treatment. This result also indicates that earlier scaling arguments which obtained an increase in the roughness of active membranes near repulsive walls upon neglecting the role played by such couplings may need to be reevaluated.

  2. Effect of polyunsaturated fatty acids and phospholipids on [3H]-vitamin E incorporation into pulmonary artery endothelial cell membranes

    International Nuclear Information System (INIS)

    Sekharam, K.M.; Patel, J.M.; Block, E.R.

    1990-01-01

    Vitamin E, a dietary antioxidant, is presumed to be incorporated into the lipid bilayer of biological membranes to an extent proportional to the amount of polyunsaturated fatty acids or phospholipids in the membrane. In the present study we evaluated the distribution of incorporated polyunsaturated fatty acids (PUFA) and phosphatidylethanolamine (PE) in various membranes of pulmonary artery endothelial cells. We also studied whether incorporation of PUFA or PE is responsible for increased incorporation of [3H]-vitamin E into the membranes of these cells. Following a 24-hr incubation with linoleic acid (18:2), 18:2 was increased by 6.9-, 9.2-, and 13.2-fold in plasma, mitochondrial, and microsomal membranes, respectively. Incorporation of 18:2 caused significant increases in the unsaturation indexes of mitochondrial and microsomal polyunsaturated fatty acyl chains (P less than .01 versus control in both membranes). Incubation with arachidonic acid (20:4) for 24 hr resulted in 1.5-, 2.3-, and 2.4-fold increases in 20:4 in plasma, mitochondrial, and microsomal membranes, respectively. The unsaturation indexes of polyunsaturated fatty acyl chains of mitochondrial and microsomal membranes also increased (P less than .01 versus control in both membranes). Although incubations with 18:2 or 20:4 resulted in several-fold increases in membrane 18:2 or 20:4 fatty acids, incorporation of [3H]-vitamin E into these membranes was similar to that in controls. Following a 24-hr incubation with PE, membrane PE content was significantly increased, and [3H]-vitamin E incorporation was also increased to a comparable degree, i.e., plasma membrane greater than mitochondria greater than microsomes. Endogenous vitamin E content of the cells was not altered because of increased incorporation of PE and [3H]-vitamin E

  3. Hamilton's equations for a fluid membrane

    International Nuclear Information System (INIS)

    Capovilla, R; Guven, J; Rojas, E

    2005-01-01

    Consider a homogeneous fluid membrane described by the Helfrich-Canham energy, quadratic in the mean curvature of the membrane surface. The shape equation that determines equilibrium configurations is fourth order in derivatives and cubic in the mean curvature. We introduce a Hamiltonian formulation of this equation which dismantles it into a set of coupled first-order equations. This involves interpreting the Helfrich-Canham energy as an action; equilibrium surfaces are generated by the evolution of space curves. Two features complicate the implementation of a Hamiltonian framework. (i) The action involves second derivatives. This requires treating the velocity as a phase-space variable and the introduction of its conjugate momentum. The canonical Hamiltonian is constructed on this phase space. (ii) The action possesses a local symmetry-reparametrization invariance. The two labels we use to parametrize points on the surface are themselves physically irrelevant. This symmetry implies primary constraints, one for each label, that need to be implemented within the Hamiltonian. The two Lagrange multipliers associated with these constraints are identified as the components of the acceleration tangential to the surface. The conservation of the primary constraints implies two secondary constraints, fixing the tangential components of the momentum conjugate to the position. Hamilton's equations are derived and the appropriate initial conditions on the phase-space variables are identified. Finally, it is shown how the shape equation can be reconstructed from these equations

  4. Membrane Lipid Replacement for chronic illnesses, aging and cancer using oral glycerolphospholipid formulations with fructooligosaccharides to restore phospholipid function in cellular membranes, organelles, cells and tissues.

    Science.gov (United States)

    Nicolson, Garth L; Ash, Michael E

    2017-09-01

    Membrane Lipid Replacement is the use of functional, oral supplements containing mixtures of cell membrane glycerolphospholipids, plus fructooligosaccharides (for protection against oxidative, bile acid and enzymatic damage) and antioxidants, in order to safely replace damaged, oxidized, membrane phospholipids and restore membrane, organelle, cellular and organ function. Defects in cellular and intracellular membranes are characteristic of all chronic medical conditions, including cancer, and normal processes, such as aging. Once the replacement glycerolphospholipids have been ingested, dispersed, complexed and transported, while being protected by fructooligosaccharides and several natural mechanisms, they can be inserted into cell membranes, lipoproteins, lipid globules, lipid droplets, liposomes and other carriers. They are conveyed by the lymphatics and blood circulation to cellular sites where they are endocytosed or incorporated into or transported by cell membranes. Inside cells the glycerolphospholipids can be transferred to various intracellular membranes by lipid globules, liposomes, membrane-membrane contact or by lipid carrier transfer. Eventually they arrive at their membrane destinations due to 'bulk flow' principles, and there they can stimulate the natural removal and replacement of damaged membrane lipids while undergoing further enzymatic alterations. Clinical trials have shown the benefits of Membrane Lipid Replacement in restoring mitochondrial function and reducing fatigue in aged subjects and chronically ill patients. Recently Membrane Lipid Replacement has been used to reduce pain and other symptoms as well as removing hydrophobic chemical contaminants, suggesting that there are additional new uses for this safe, natural medicine supplement. This article is part of a Special Issue entitled: Membrane Lipid Therapy: Drugs Targeting Biomembranes edited by Pablo V. Escribá. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights

  5. Model mass spectrometric study of competitive interactions of antimicrobial bisquaternary ammonium drugs and aspirin with membrane phospholipids

    Directory of Open Access Journals (Sweden)

    Vekey K.

    2013-03-01

    Full Text Available The aim of the study is to reveal molecular mechanisms of possible activity modulation of antimicrobial bis-quaternary ammonium compounds (BQAC and aspirin (ASP through noncovalent competitive complexation under their combined introduction into the model systems with membrane phospholipids. Methods. Binary and triple systems containing either decamethoxinum or ethonium, or thionium and aspirin, as well as dipalmitoyl-phosphatidylcholine (DPPC have been investigated by electrospray ionization mass spectrometry. Results. Basing on the analysis of associates recorded in the mass spectra, the types of nonocovalent complexes formed in the systems studied were determined and the supposed role of the complexation in the BQAC and ASP activity modulation was discussed. The formation of associates of BQAC dications with ASP anion is considered as one of the possible ways of deactivation of ionic forms of the medications. The formation of stable complexes of BQAC with DPPC and ASP with DPPC in binary systems as well as the complexes distribution in triple-components systems BQAC:ASP:DPPC point to the existence of competition between drugs of these two types for the binding to DPPC. Conclusions. The results obtained point to the competitive complexation in the model molecular systems containing the BQAC, aspirin and membrane phospholipids. The observed phenomenon testifies to the possibility of modulating the activity of bisquaternary antimicrobial agents and aspirin under their combined usage, due to the competition between the drugs for binding to the target membrane phospholipid molecules and also due to the formation of stable noncovalent complexes between BQAC and ASP.

  6. Membrane-surfactant interactions. The role of surfactant in mitochondrial complex III-phospholipid-Triton X-100 mixed micelles

    International Nuclear Information System (INIS)

    Valpuesta, J.M.; Arrondo, J.L.; Barbero, M.C.; Pons, M.; Goni, F.M.

    1986-01-01

    Complex III (ubiquinol-cytochrome c reductase) was purified from beef heart mitochondria in the form of protein-phospholipid-Triton X-100 mixed micelles (about 1:80:100 molar ratio). Detergent may be totally removed by sucrose density gradient centrifugation, and the resulting lipoprotein complexes retain full enzyme activity. In order to understand the role of surfactant in the mixed micelles, and the interaction of Triton X-100 with integral membrane proteins and phospholipid bilayers, both the protein-lipid-surfactant mixed micelles and the detergent-free lipoprotein system were examined from the point of view of particle size and ultrastructure, enzyme activity, tryptophan fluorescence quenching, 31P NMR, and Fourier transform infrared spectroscopy. The NMR and IR spectroscopic studies show that surfactant withdrawal induces a profound change in phospholipid architecture, from a micellar to a lamellar-like phase. However, electron microscopic observations fail to reveal the existence of lipid bilayers in the absence of detergent. We suggest that, under these conditions, the lipid:protein molar ratio (80:1) is too low to permit the formation of lipid bilayer planes, but the relative orientation and mobility of phospholipids with respect to proteins is similar to that of the lamellar phase. Protein conformational changes are also detected as a consequence of surfactant removal. Fourier transform infrared spectroscopy indicates an increase of peptide beta-structure in the absence of Triton X-100; changes in the amide II/amide I intensity ratio are also detected, although the precise meaning of these observations is unclear

  7. Slaved diffusion in phospholipid bilayers

    Science.gov (United States)

    Zhang, Liangfang; Granick, Steve

    2005-01-01

    The translational diffusion of phospholipids in supported fluid bilayers splits into two populations when polyelectrolytes adsorb at incomplete surface coverage. Spatially resolved measurements using fluorescence correlation spectroscopy show that a slow mode, whose magnitude scales inversely with the degree of polymerization of the adsorbate, coexists with a fast mode characteristic of naked lipid diffusion. Inner and outer leaflets of the bilayer are affected nearly equally. Mobility may vary from spot to spot on the membrane surface, despite the lipid composition being the same. This work offers a mechanism to explain how nanosized domains with reduced mobility arise in lipid membranes. PMID:15967988

  8. Conformations of double-headed, triple-tailed phospholipid oxidation lipid products in model membranes

    DEFF Research Database (Denmark)

    Hermetter, Albin; Kopec, Wojciech; Khandelia, Himanshu

    2013-01-01

    Products of phospholipid oxidation can produce lipids with a carbonyl moiety at the end of a shortened lipid acyl tail, such as 1-palmitoyl-2-(5-oxovaleroyl)-sn-glycero-3-phosphocholine (POVPC). The carbonyl tail of POVPC can covalently bond to the free tertiary amine of a phosphatidylethanolamine...

  9. General model of phospholipid bilayers in fluid phase within the single chain mean field theory

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Yachong; Baulin, Vladimir A. [Departament d’Enginyeria Química, Universitat Rovira i Virgili, Av. dels Paisos Catalans 26, 43007 Tarragona (Spain); Pogodin, Sergey [Institute of Chemical Research of Catalonia, ICIQ, Av. Paisos Catalans 16, 43007 Tarragona (Spain)

    2014-05-07

    Coarse-grained model for saturated phospholipids: 1,2-didecanoyl-sn-glycero-3-phosphocholine (DCPC), 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC), 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) and unsaturated phospholipids: 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), 1,2- dioleoyl-sn-glycero-3-phosphocholine (DOPC) is introduced within the single chain mean field theory. A single set of parameters adjusted for DMPC bilayers gives an adequate description of equilibrium and mechanical properties of a range of saturated lipid molecules that differ only in length of their hydrophobic tails and unsaturated (POPC, DOPC) phospholipids which have double bonds in the tails. A double bond is modeled with a fixed angle of 120°, while the rest of the parameters are kept the same as saturated lipids. The thickness of the bilayer and its hydrophobic core, the compressibility, and the equilibrium area per lipid correspond to experimentally measured values for each lipid, changing linearly with the length of the tail. The model for unsaturated phospholipids also fetches main thermodynamical properties of the bilayers. This model is used for an accurate estimation of the free energies of the compressed or stretched bilayers in stacks or multilayers and gives reasonable estimates for free energies. The proposed model may further be used for studies of mixtures of lipids, small molecule inclusions, interactions of bilayers with embedded proteins.

  10. Organic fluid permeation through fluoropolymer membranes

    Science.gov (United States)

    Nemser, Stuart M.; Kosaraju, Praveen; Bowser, John

    2015-07-14

    Separation of the components of liquid mixtures is achieved by contacting a liquid mixture with a nonporous membrane having a fluoropolymer selectively permeable layer and imposing a pressure gradient across the membrane from feed side to permeate side. Unusually high transmembrane flux is obtained when the membrane is subjected to one or more process conditions prior to separation. These include (a) leaving some residual amount of membrane casting solvent in the membrane, and (b) contacting the membrane with a component of the mixture to be separated for a duration effective to saturate the membrane with the component.

  11. Supported Phospholipid Membranes Formation at a Gel Electrode and Transport of Divalent Cations across them

    Czech Academy of Sciences Publication Activity Database

    Navrátil, Tomáš; Šestáková, Ivana; Mareček, Vladimír

    2011-01-01

    Roč. 6, č. 1 (2011), s. 6032-6046 ISSN 1452-3981 R&D Projects: GA AV ČR IAA400400806; GA ČR GAP206/11/1638 Institutional research plan: CEZ:AV0Z40400503 Keywords : gel * agar * phospholipids Subject RIV: CG - Electrochemistry Impact factor: 3.729, year: 2011 http://www.electrochemsci.org/list11.htm

  12. Optimization of transversal relaxation of nitroxides for pulsed electron-electron double resonance spectroscopy in phospholipid membranes.

    Science.gov (United States)

    Dastvan, Reza; Bode, Bela E; Karuppiah, Muruga Poopathi Raja; Marko, Andriy; Lyubenova, Sevdalina; Schwalbe, Harald; Prisner, Thomas F

    2010-10-28

    Pulsed electron-electron double resonance (PELDOR) spectroscopy is increasingly applied to spin-labeled membrane proteins. However, after reconstitution into liposomes, spin labels often exhibit a much faster transversal relaxation (T(m)) than in detergent micelles, thus limiting application of the method in lipid bilayers. In this study, the main reasons for enhanced transversal relaxation in phospholipid membranes were investigated systematically by use of spin-labeled derivatives of stearic acid and phosphatidylcholine as well as spin-labeled derivatives of the channel-forming peptide gramicidin A under the conditions typically employed for PELDOR distance measurements. Our results clearly show that dephasing due to instantaneous diffusion that depends on dipolar interaction among electron spins is an important contributor to the fast echo decay in cases of high local concentrations of spin labels in membranes. The main difference between spin labels in detergent micelles and membranes is their local concentration. Consequently, avoiding spin clustering and suppressing instantaneous diffusion is the key step for maximizing PELDOR sensitivity in lipid membranes. Even though proton spin diffusion is an important relaxation mechanism, only in samples of low local concentrations does deuteration of acyl chains and buffer significantly prolong T(m). In these cases, values of up to 7 μs have been achieved. Furthermore, our study revealed that membrane composition and labeling position in the membrane can also affect T(m), either by promoting the segregation of spin-labeled species or by altering their exposure to matrix protons. Effects of other experimental parameters including temperature (<50 K), presence of oxygen, and cryoprotectant type are negligible under our experimental conditions.

  13. Membrane phospholipid composition may contribute to exceptional longevity of the naked mole-rat (Heterocephalus glaber): a comparative study using shotgun lipidomics.

    Science.gov (United States)

    Mitchell, Todd W; Buffenstein, Rochelle; Hulbert, A J

    2007-11-01

    Phospholipids containing highly polyunsaturated fatty acids are particularly prone to peroxidation and membrane composition may therefore influence longevity. Phospholipid molecules, in particular those containing docosahexaenoic acid (DHA), from the skeletal muscle, heart, liver and liver mitochondria were identified and quantified using mass-spectrometry shotgun lipidomics in two similar-sized rodents that show an approximately 9-fold difference in maximum lifespan. The naked mole rat is the longest-living rodent known with a maximum lifespan of >28 years. Total phospholipid distribution is similar in tissues of both species; DHA is only found in phosphatidylcholines (PC), phosphatidylethanolamines (PE) and phosphatidylserines (PS), and DHA is relatively more concentrated in PE than PC. Naked mole-rats have fewer molecular species of both PC and PE than do mice. DHA-containing phospholipids represent 27-57% of all phospholipids in mice but only 2-6% in naked mole-rats. Furthermore, while mice have small amounts of di-polyunsaturated PC and PE, these are lacking in naked mole-rats. Vinyl ether-linked phospholipids (plasmalogens) are higher in naked mole-rat tissues than in mice. The lower level of DHA-containing phospholipids suggests a lower susceptibility to peroxidative damage in membranes of naked mole-rats compared to mice. Whereas the high level of plasmalogens might enhance membrane antioxidant protection in naked mole-rats compared to mice. Both characteristics possibly contribute to the exceptional longevity of naked mole-rats and may indicate a special role for peroxisomes in this extended longevity.

  14. Intrauterine Defensive Mechanism of Amniotic Fluid and Fetal Membranes

    OpenAIRE

    金山, 尚裕

    1994-01-01

    To determine the intrauterine defensive role of urinary trypsin inhibitor (UTI), we studied the effects of UTI in amniotic fluid, fetal membranes and myometrium. The level of UTI was 94±34U/ml in neonatal urine (compared to adult urine 8.0±6.0U/ml) and 88±37U/ml in amniotic fluid. This may indicate that the main source of UTI in the amniotic fluid is the fetal urine. UTI was found to be concentrated in vernix, fetal intestine, amniotic membranes and uterine myometrium. Immunostaining of term ...

  15. Softening of phospholipid membranes by the adhesion of silica nanoparticles - as seen by neutron spin-echo (NSE)

    Science.gov (United States)

    Hoffmann, Ingo; Michel, Raphael; Sharp, Melissa; Holderer, Olaf; Appavou, Marie-Sousai; Polzer, Frank; Farago, Bela; Gradzielski, Michael

    2014-05-01

    The interactions between nanoparticles and vesicles are of significant interest both from a fundamental as well as from a practical point of view, as vesicles can serve as a model system for cell membranes. Accordingly the effect of nanoparticles that bind to the vesicle bilayer is very important with respect to understanding their biological impact and also may shed some light on the mechanisms behind the effect of nanotoxicity. In this study we have investigated the influence of small adsorbed silica nanoparticles (SiNPs) on the structure of zwitterionic DOPC vesicles. By a combination of SANS, cryo-TEM, and DLS, we observed that the SiNPs are bound to the outer vesicle surface without significantly affecting the vesicle structure. Most interestingly, by means of neutron spin-echo (NSE) local bilayer fluctuations were studied and one finds a small but marked decrease of the membrane rigidity upon binding of the nanoparticles. This surprising finding may be a relevant aspect for the further understanding of the effects that nanoparticles have on phospholipid bilayers.The interactions between nanoparticles and vesicles are of significant interest both from a fundamental as well as from a practical point of view, as vesicles can serve as a model system for cell membranes. Accordingly the effect of nanoparticles that bind to the vesicle bilayer is very important with respect to understanding their biological impact and also may shed some light on the mechanisms behind the effect of nanotoxicity. In this study we have investigated the influence of small adsorbed silica nanoparticles (SiNPs) on the structure of zwitterionic DOPC vesicles. By a combination of SANS, cryo-TEM, and DLS, we observed that the SiNPs are bound to the outer vesicle surface without significantly affecting the vesicle structure. Most interestingly, by means of neutron spin-echo (NSE) local bilayer fluctuations were studied and one finds a small but marked decrease of the membrane rigidity upon

  16. Membrane curvature, lipid segregation, and structural transitions for phospholipids under dual-solvent stress

    International Nuclear Information System (INIS)

    Rand, R.P.; Fuller, N.L.; Gruner, S.M.; Parsegian, V.A.

    1990-01-01

    Amphiphiles respond both to polar and to nonpolar solvents. In this paper X-ray diffraction and osmotic stress have been used to examine the phase behavior, the structural dimensions, and the work of deforming the monolayer-lined aqueous cavities formed by mixtures of dioleoylphosphatidylethanolamine (DOPE) and dioleoylphosphatidylcholine (DOPC) as a function of the concentration of two solvents, water and tetradecane (td). In the absence of td, most PE/PC mixtures show only lamellar phases in excess water; all of these become single reverse hexagonal (H II ) phases with addition of excess td. The spontaneous radius of curvature R 0 of lipid monolayers, as expressed in these H II phases, is allowed by the relief of hydrocarbon chain stress by td; R 0 increases with the ratio DOPC/DOPE. Single H II phases stressed by limited water or td show several responses. (a) the molecular area is compressed at the polar end of the molecule and expanded at the hydrocarbon ends. (b) For circularly symmetrical water cylinders, the degrees of hydrocarbon chain splaying and polar group compression are different for molecules aligned in different directions around the water cylinder. (c) A pivotal position exists along the length of the phospholipid molecule where little area change occurs as the monolayer is bent to increasing curvatures. (d) By defining R 0 at the pivotal position, the authors find that measured energies are well fit by a quadratic bending energy. (e) For lipid mixtures, enforced deviation of the H II monolayer from R 0 is sufficiently powerful to cause demixing of the phospholipids in a way suggesting that the DOPE/DOPC ratio self-adjusts so that its R 0 matches the amount of td or water available, i.e., that curvature energy is minimized

  17. Single lipid vesicle assay for characterizing single-enzyme kinetics of phospholipid hydrolysis in a complex biological fluid.

    Science.gov (United States)

    Tabaei, Seyed R; Rabe, Michael; Zetterberg, Henrik; Zhdanov, Vladimir P; Höök, Fredrik

    2013-09-25

    Imaging of individual lipid vesicles is used to track single-enzyme kinetics of phospholipid hydrolysis. The method is employed to quantify the catalytic activity of phospholipase A2 (PLA2) in both pure and complex biological fluids. The measurements are demonstrated to offer a subpicomolar limit of detection (LOD) of human secretory PLA2 (sPLA2) in up to 1000-fold-diluted cerebrospinal fluid (CSF). An additional new feature provided by the single-enzyme sensitivity is that information about both relative concentration variations of active sPLA2 in CSF and the specific enzymatic activity can be simultaneously obtained. When CSF samples from healthy controls and individuals diagnosed with Alzheimer's disease (AD) are analyzed, the specific enzymatic activity is found to be preserved within 7% in the different CSF samples whereas the enzyme concentration differs by up to 56%. This suggests that the previously reported difference in PLA2 activity in CSF samples from healthy and AD individuals originates from differences in the PLA2 expression level rather than from the enzyme activity. Conventional ensemble averaging methods used to probe sPLA2 activity do not allow one to obtain such information. Together with an improvement in the LOD of at least 1 order of magnitude compared to that of conventional assays, this suggests that the method will become useful in furthering our understanding of the role of PLA2 in health and disease and in detecting the pharmacodynamic effects of PLA2-targeting drug candidates.

  18. Complete dissociation of the HIV-1 gp41 ectodomain and membrane proximal regions upon phospholipid binding

    International Nuclear Information System (INIS)

    Roche, Julien; Louis, John M.; Aniana, Annie; Ghirlando, Rodolfo; Bax, Ad

    2015-01-01

    The envelope glycoprotein gp41 mediates the process of membrane fusion that enables entry of the HIV-1 virus into the host cell. Strong lipid affinity of the ectodomain suggests that its heptad repeat regions play an active role in destabilizing membranes by directly binding to the lipid bilayers and thereby lowering the free-energy barrier for membrane fusion. In such a model, immediately following the shedding of gp120, the N-heptad and C-heptad helices dissociate and melt into the host cell and viral membranes, respectively, pulling the destabilized membranes into juxtaposition, ready for fusion. Post-fusion, reaching the final 6-helix bundle (6HB) conformation then involves competition between intermolecular interactions needed for formation of the symmetric 6HB trimer and the membrane affinity of gp41’s ectodomain, including its membrane-proximal regions. Our solution NMR study of the structural and dynamic properties of three constructs containing the ectodomain of gp41 with and without its membrane-proximal regions suggests that these segments do not form inter-helical interactions until the very late steps of the fusion process. Interactions between the polar termini of the heptad regions, which are not associating with the lipid surface, therefore may constitute the main driving force initiating formation of the final post-fusion states. The absence of significant intermolecular ectodomain interactions in the presence of dodecyl phosphocholine highlights the importance of trimerization of gp41’s transmembrane helix to prevent complete dissociation of the trimer during the course of fusion

  19. Complete dissociation of the HIV-1 gp41 ectodomain and membrane proximal regions upon phospholipid binding

    Energy Technology Data Exchange (ETDEWEB)

    Roche, Julien; Louis, John M.; Aniana, Annie [National Institute of Diabetes and Digestive and Kidney Diseases, Laboratory of Chemical Physics (United States); Ghirlando, Rodolfo [National Institutes of Health, Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases (United States); Bax, Ad, E-mail: bax@nih.gov [National Institute of Diabetes and Digestive and Kidney Diseases, Laboratory of Chemical Physics (United States)

    2015-04-15

    The envelope glycoprotein gp41 mediates the process of membrane fusion that enables entry of the HIV-1 virus into the host cell. Strong lipid affinity of the ectodomain suggests that its heptad repeat regions play an active role in destabilizing membranes by directly binding to the lipid bilayers and thereby lowering the free-energy barrier for membrane fusion. In such a model, immediately following the shedding of gp120, the N-heptad and C-heptad helices dissociate and melt into the host cell and viral membranes, respectively, pulling the destabilized membranes into juxtaposition, ready for fusion. Post-fusion, reaching the final 6-helix bundle (6HB) conformation then involves competition between intermolecular interactions needed for formation of the symmetric 6HB trimer and the membrane affinity of gp41’s ectodomain, including its membrane-proximal regions. Our solution NMR study of the structural and dynamic properties of three constructs containing the ectodomain of gp41 with and without its membrane-proximal regions suggests that these segments do not form inter-helical interactions until the very late steps of the fusion process. Interactions between the polar termini of the heptad regions, which are not associating with the lipid surface, therefore may constitute the main driving force initiating formation of the final post-fusion states. The absence of significant intermolecular ectodomain interactions in the presence of dodecyl phosphocholine highlights the importance of trimerization of gp41’s transmembrane helix to prevent complete dissociation of the trimer during the course of fusion.

  20. Promiscuous and specific phospholipid binding by domains in ZAC, a membrane-associated Arabidopsis protein with an ARF GAP zinc finger and a C2 domain

    DEFF Research Database (Denmark)

    Jensen, R B; Lykke-Andersen, K; Frandsen, G I

    2000-01-01

    domain are separated by a region without homology to other known proteins. Zac promoter/beta-glucuronidase reporter assays revealed highest expression levels in flowering tissue, rosettes and roots. ZAC protein was immuno-detected mainly in association with membranes and fractionated with Golgi...... and plasma membrane marker proteins. ZAC membrane association was confirmed in assays by a fusion between ZAC and the green fluorescence protein and prompted an analysis of the in vitro phospholipid-binding ability of ZAC. Phospholipid dot-blot and liposome-binding assays indicated that fusion proteins...... zinc finger motif, but proteins containing only the zinc finger domain (residues 1-105) did not bind PI-3-P. Recombinant ZAC possessed GTPase-activating activity on Arabidopsis ARF proteins. These data identify a novel PI-3-P-binding protein region and thereby provide evidence...

  1. Fluid transportation mechanisms by a coupled system of elastic membranes and magnetic fluids

    International Nuclear Information System (INIS)

    Ido, Y.; Tanaka, K.; Sugiura, Y.

    2002-01-01

    The basic properties of the fluid transportation mechanism that is produced by the coupled waves propagating along a thin elastic membrane covering a magnetic fluid layer in a shallow and long rectangular vessel are investigated. It is shown that the progressive magnetic field induced by the rectangular pulses generates sinusoidal vibration of the displacement of elastic membrane and makes the system work more efficiently than the magnetic field induced by the pulse-width-modulation method

  2. MICOS and phospholipid transfer by Ups2-Mdm35 organize membrane lipid synthesis in mitochondria.

    Science.gov (United States)

    Aaltonen, Mari J; Friedman, Jonathan R; Osman, Christof; Salin, Bénédicte; di Rago, Jean-Paul; Nunnari, Jodi; Langer, Thomas; Tatsuta, Takashi

    2016-06-06

    Mitochondria exert critical functions in cellular lipid metabolism and promote the synthesis of major constituents of cellular membranes, such as phosphatidylethanolamine (PE) and phosphatidylcholine. Here, we demonstrate that the phosphatidylserine decarboxylase Psd1, located in the inner mitochondrial membrane, promotes mitochondrial PE synthesis via two pathways. First, Ups2-Mdm35 complexes (SLMO2-TRIAP1 in humans) serve as phosphatidylserine (PS)-specific lipid transfer proteins in the mitochondrial intermembrane space, allowing formation of PE by Psd1 in the inner membrane. Second, Psd1 decarboxylates PS in the outer membrane in trans, independently of PS transfer by Ups2-Mdm35. This latter pathway requires close apposition between both mitochondrial membranes and the mitochondrial contact site and cristae organizing system (MICOS). In MICOS-deficient cells, limiting PS transfer by Ups2-Mdm35 and reducing mitochondrial PE accumulation preserves mitochondrial respiration and cristae formation. These results link mitochondrial PE metabolism to MICOS, combining functions in protein and lipid homeostasis to preserve mitochondrial structure and function. © 2016 Aaltonen et al.

  3. Annexin A2 in amniotic fluid: correlation with histological chorioamnionitis, preterm premature rupture of membranes, and subsequent preterm delivery.

    Science.gov (United States)

    Namba, Fumihiko; Ina, Shihomi; Kitajima, Hiroyuki; Yoshio, Hiroyuki; Mimura, Kazuya; Saito, Shigeru; Yanagihara, Itaru

    2012-01-01

    The aim of this study was to determine whether amniotic fluid levels of annexin A2, a phospholipid-binding protein that is abundant in amnion and regulates fibrin homeostasis, are associated with histological chorioamnionitis, preterm premature rupture of the membranes, and subsequent preterm delivery. Amniotic fluid was obtained from 55 pregnant women with preterm labor and/or preterm premature rupture of the membranes before 32weeks of gestation, and amniotic fluid levels of annexin A2 were measured with a sandwich enzyme-linked immunosorbent assay. Amniotic fluid levels of annexin A2 in patients with histological chorioamnionitis was higher than that in the remainder (P=0.053), whereas amniotic fluid levels of annexin A2 in patients with preterm premature rupture of the membranes was significantly higher than that in the remainder (P=0.002). Amniotic levels of annexin A2 was a fair test (area under receiver-operator characteristic curve=0.679), and amniotic fluid levels of annexin A2>878.2ng/mL had a sensitivity of 68.8%, a specificity of 65.2%, a positive predictive value of 73.3%, and a negative predictive value of 60.0% for predicting delivery within 2weeks after amniotic fluid sampling. Furthermore, the combined use of amniotic fluid cut-off levels of 878.2ng/mL for annexin A2 and 13.3ng/mL for interleukin-8 improved the specificity (91.3%) and the positive predictive value (89.5%). We identified amniotic fluid levels of annexin A2, especially in combination with amniotic fluid levels of interleukin-8, as a novel predictive marker for preterm delivery. © 2011 The Authors. Journal of Obstetrics and Gynaecology Research © 2011 Japan Society of Obstetrics and Gynecology.

  4. The chloroplasts membrane phospholipids of Chlamydomonas reinhardii mutant not forming the Photosystem 2

    International Nuclear Information System (INIS)

    Trusova, V.M.; Ladygin, V.G.; Mezentsev, V.V.; Molchanov, M.I.

    1987-01-01

    Study on a component composition and physical state of photosynthetic membranes of Chlamydomonas chloroplasts of the wild type and mutant A-110 with disturbance of electron transfer chain in the photosystem 2 region permitted to conclude that 170 A diameter particles localized on the internal hydrophobic surface of membrane chips are deleted with respect to phosphatidylglycerin. The results obtained permit to suggest that the formation of protein-lipid complexes containing phosphatidylglycerins is suppressed in mutant A-110 which is not capable of the lamellar system differentation in

  5. Biophysical study of resin acid effects on phospholipid membrane structure and properties

    DEFF Research Database (Denmark)

    Jagalski, Vivien; Barker, Robert; Topgaard, Daniel

    2016-01-01

    Hydrophobic resin acids (RAs) are synthesized by conifer trees as part of their defense mechanisms. One of the functions of RAs in plant defense is suggested to be the perturbation of the cellular membrane. However, there is a vast diversity of chemical structures within this class of molecules, ...

  6. Molecular Dynamics Simulations of Phospholipid Membranes and Their Interaction with Phospholipase A2

    NARCIS (Netherlands)

    Berendsen, Herman; Egberts, Bert; Marrink, Siewert; Ahlstroem, Peter; Pullman, Alberte; Jortner, Joshua; Pullman, Bernhard

    1992-01-01

    Molecular Dynamics computer simulations have been carried out both on simplified model systems of biological membranes and on di(palmitoyl)lecithin/water multibilayers. The results, which agree with experimental data on chain order parameters, show a considerable disorder with atomic distributions

  7. Mechanical collapse of confined fluid membrane vesicles.

    Science.gov (United States)

    Rim, Jee E; Purohit, Prashant K; Klug, William S

    2014-11-01

    Compact cylindrical and spherical invaginations are common structural motifs found in cellular and developmental biology. To understand the basic physical mechanisms that produce and maintain such structures, we present here a simple model of vesicles in confinement, in which mechanical equilibrium configurations are computed by energy minimization, balancing the effects of curvature elasticity, contact of the membrane with itself and the confining geometry, and adhesion. For cylindrical confinement, the shape equations are solved both analytically and numerically by finite element analysis. For spherical confinement, axisymmetric configurations are obtained numerically. We find that the geometry of invaginations is controlled by a dimensionless ratio of the adhesion strength to the bending energy of an equal area spherical vesicle. Larger adhesion produces more concentrated curvatures, which are mainly localized to the "neck" region where the invagination breaks away from its confining container. Under spherical confinement, axisymmetric invaginations are approximately spherical. For extreme confinement, multiple invaginations may form, bifurcating along multiple equilibrium branches. The results of the model are useful for understanding the physical mechanisms controlling the structure of lipid membranes of cells and their organelles, and developing tissue membranes.

  8. Interaction of melittin with mixed phospholipid membranes composed of dimyristoylphosphatidylcholine and dimyristoylphosphatidylserine studied by deuterium NMR

    Energy Technology Data Exchange (ETDEWEB)

    Dempsey, C.; Bitbol, M.; Watts, A. (Oxford Univ. (England))

    1989-08-08

    The interaction of bee venom melittin with mixed phospholipid bilayers composed of dimyristoylphosphatidylcholine deuterated in the {alpha}- and {beta}-methylenes of the choline head group (DMPC-d{sub 4}) and dimyristoylphosphatidylserine deuterated in the {alpha}-methylene and {beta}-CH positions of the serine head group (DMPS-d{sub 3}) was studied in ternary mixtures by using deuterium NMR spectroscopy. The changes in the deuterium quadrupole splittings of the head-group deuteriomethylenes of DMPC-d{sub 4} induced by DMPS in binary mixtures were systematically reversed by increasing concentrations of melittin, so that at a melittin concentration of 4 mol % relative to total lipid the deuterium NMR spectrum from DMPC-d{sub 4} in the ternary mixture was similar to the spectrum from pure DMPC-d{sub 4} bilayers. The absence of deuterium NMR signals arising from melittin-bound DMPS in ternary mixtures containing DMPS-d{sub 3} indicates that the reversal by melittin of the effects of DMPS on the quadrupole splittings of DMPC-d{sub 4} results from the response of the choline head group to the net surface charge rather than from phase separation of melittin-DMPS complexes. The similarity in the effects of the two cationic but otherwise dissimilar peptides indicates that the DMPS head group responds to the surface charge resulting from the presence in the bilayer of charged amphiphiles, in a manner analogous to the response of the choline head group of phosphatidylcholine to the bilayer surface charge. The presence of DMPS greatly stabilized DMPC bilayers with respect to melittin-induced micellization, indicating that the latter effect of melittin may not be important for the hemolytic activity of the peptide.

  9. Interaction of melittin with mixed phospholipid membranes composed of dimyristoylphosphatidylcholine and dimyristoylphosphatidylserine studied by deuterium NMR

    International Nuclear Information System (INIS)

    Dempsey, C.; Bitbol, M.; Watts, A.

    1989-01-01

    The interaction of bee venom melittin with mixed phospholipid bilayers composed of dimyristoylphosphatidylcholine deuterated in the α- and β-methylenes of the choline head group (DMPC-d 4 ) and dimyristoylphosphatidylserine deuterated in the α-methylene and β-CH positions of the serine head group (DMPS-d 3 ) was studied in ternary mixtures by using deuterium NMR spectroscopy. The changes in the deuterium quadrupole splittings of the head-group deuteriomethylenes of DMPC-d 4 induced by DMPS in binary mixtures were systematically reversed by increasing concentrations of melittin, so that at a melittin concentration of 4 mol % relative to total lipid the deuterium NMR spectrum from DMPC-d 4 in the ternary mixture was similar to the spectrum from pure DMPC-d 4 bilayers. The absence of deuterium NMR signals arising from melittin-bound DMPS in ternary mixtures containing DMPS-d 3 indicates that the reversal by melittin of the effects of DMPS on the quadrupole splittings of DMPC-d 4 results from the response of the choline head group to the net surface charge rather than from phase separation of melittin-DMPS complexes. The similarity in the effects of the two cationic but otherwise dissimilar peptides indicates that the DMPS head group responds to the surface charge resulting from the presence in the bilayer of charged amphiphiles, in a manner analogous to the response of the choline head group of phosphatidylcholine to the bilayer surface charge. The presence of DMPS greatly stabilized DMPC bilayers with respect to melittin-induced micellization, indicating that the latter effect of melittin may not be important for the hemolytic activity of the peptide

  10. A numerical method for interaction problems between fluid and membranes with arbitrary permeability for fluid

    Science.gov (United States)

    Miyauchi, Suguru; Takeuchi, Shintaro; Kajishima, Takeo

    2017-09-01

    We develop a numerical method for fluid-membrane interaction accounting for permeation of the fluid using a non-conforming mesh to the membrane shape. To represent the permeation flux correctly, the proposed finite element discretization incorporates the discontinuities in the velocity gradient and pressure on the membrane surface with specially selected base functions. The discontinuities are represented with independent variables and determined to satisfy the governing equations including the interfacial condition on the permeation. The motions of the fluid, membrane and permeation flux are coupled monolithically and time-advanced fully-implicitly. The validity and effectiveness of the proposed method are demonstrated by several two-dimensional fluid-membrane interaction problems of Stokes flows by comparing with the analytical models and numerical results obtained by other methods. The reproduced sharp discontinuities are found to be essential to suppress the non-physical permeation flux. Further, combined with the numerical treatment for the solute concentration across the membrane, the proposed method is applied to a fluid-structure interaction problem including the osmotic pressure difference.

  11. Interactions of Borneol with DPPC Phospholipid Membranes: A Molecular Dynamics Simulation Study

    Directory of Open Access Journals (Sweden)

    Qianqian Yin

    2014-11-01

    Full Text Available Borneol, known as a “guide” drug in traditional Chinese medicine, is widely used as a natural penetration enhancer in modern clinical applications. Despite a large number of experimental studies on borneol’s penetration enhancing effect, the molecular basis of its action on bio-membranes is still unclear. We carried out a series of coarse-grained molecular dynamics simulations with the borneol concentration ranging from 3.31% to 54.59% (v/v, lipid-free basis to study the interactions of borneol with aDPPC(1,2-dipalmitoylsn-glycero-3-phosphatidylcholine bilayer membrane, and the temperature effects were also considered. At concentrations below 21.89%, borneol’s presence only caused DPPC bilayer thinning and an increase in fluidity; A rise in temperature could promote the diffusing progress of borneol. When the concentration was 21.89% or above, inverted micelle-like structures were formed within the bilayer interior, which led to increased bilayer thickness, and an optimum temperature was found for the interaction of borneol with the DPPC bilayer membrane. These findings revealed that the choice of optimal concentration and temperature is critical for a given application in which borneol is used as a penetration enhancer. Our results not only clarify some molecular basis for borneol’s penetration enhancing effects, but also provide some guidance for the development and applications of new preparations containing borneol.

  12. Protection of DPPC phospholipid liposomal membrane against radiation oxidative damage by antioxidants

    Energy Technology Data Exchange (ETDEWEB)

    Marathe, D.L.; Pandey, B.N.; Mishra, K.P [Bhabha Atomic Research Centre, Mumbai (India)

    2000-05-01

    Investigations in our laboratory on egg lecithin liposomes have recently showed a marked protection against damage by gamma radiation when cholesterol was present in the composition of vesicles suggesting a role of bilayer molecular architecture in the mechanism of free radical mediated lipid peroxidation. Present study was designed to determine the changes in bilayer permeability in DPPC unilamelar vesicles after exposure to gamma radiation by monitoring the leakage of pre-loaded carboxyfluorescein (CF), a marker loaded in aqueous interior of vesicle and fluidity alterations in the bilayer using fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH), a membrane bilayer probe. It was found that radiation doses of an order of magnitude higher were required to produce detectable changes in vesicles of DPPC than in the vesicles of egg lecithin suggesting a modulating role of chemical nature of composition in the membrane radiation sensitivity. It was significant to find that the leakage of CF from and incorporation of DPH into vesicle bilayer showed similar response pattern to radiation doses (0.1-6 kGy) which was also found to be dose rate dependent. Presence of antioxidants; alpha-tocopherol (0.15 mole %) in the bilayer membrane or ascorbic acid (0.1 mM) in the aqueous region significantly protected DPPC vesicles from radiation damage as determined from DPH uptake kinetics suggesting involvement of reactive free radicals of lipids as well as water radicals in the mechanism of membrane peroxidative damage. The magnitude of protection was found to increase with the increasing concentration of both these antioxidants but comparisons showed that {alpha}-tocopherol was far more effective in protecting the vesicles than ascorbic acid. These results contribute to our understanding of the mechanism of radiation oxidative damage and its modification by radical scavenging and/or organizational modulation which emphasize the importance of structure and composition of

  13. Protection of DPPC phospholipid liposomal membrane against radiation oxidative damage by antioxidants

    International Nuclear Information System (INIS)

    Marathe, D.L.; Pandey, B.N.; Mishra, K.P

    2000-01-01

    Investigations in our laboratory on egg lecithin liposomes have recently showed a marked protection against damage by gamma radiation when cholesterol was present in the composition of vesicles suggesting a role of bilayer molecular architecture in the mechanism of free radical mediated lipid peroxidation. Present study was designed to determine the changes in bilayer permeability in DPPC unilamelar vesicles after exposure to gamma radiation by monitoring the leakage of pre-loaded carboxyfluorescein (CF), a marker loaded in aqueous interior of vesicle and fluidity alterations in the bilayer using fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH), a membrane bilayer probe. It was found that radiation doses of an order of magnitude higher were required to produce detectable changes in vesicles of DPPC than in the vesicles of egg lecithin suggesting a modulating role of chemical nature of composition in the membrane radiation sensitivity. It was significant to find that the leakage of CF from and incorporation of DPH into vesicle bilayer showed similar response pattern to radiation doses (0.1-6 kGy) which was also found to be dose rate dependent. Presence of antioxidants; alpha-tocopherol (0.15 mole %) in the bilayer membrane or ascorbic acid (0.1 mM) in the aqueous region significantly protected DPPC vesicles from radiation damage as determined from DPH uptake kinetics suggesting involvement of reactive free radicals of lipids as well as water radicals in the mechanism of membrane peroxidative damage. The magnitude of protection was found to increase with the increasing concentration of both these antioxidants but comparisons showed that α-tocopherol was far more effective in protecting the vesicles than ascorbic acid. These results contribute to our understanding of the mechanism of radiation oxidative damage and its modification by radical scavenging and/or organizational modulation which emphasize the importance of structure and composition of

  14. Antioxidant effect of 4-nerolidylcatechol and α-tocopherol in erythrocyte ghost membranes and phospholipid bilayers

    Science.gov (United States)

    Fernandes, K.S.; Silva, A.H.M.; Mendanha, S.A.; Rezende, K.R.; Alonso, A.

    2013-01-01

    4-Nerolidylcatechol (4-NC) is found in Pothomorphe umbellata root extracts and is reported to have a topical protective effect against UVB radiation-induced skin damage, toxicity in melanoma cell lines, and antimalarial activity. We report a comparative study of the antioxidant activity of 4-NC and α-tocopherol against lipid peroxidation initiated by two free radical-generating systems: 2,2′-azobis(2-aminopropane) hydrochloride (AAPH) and FeSO4/H2O2, in red blood cell ghost membranes and in egg phosphatidylcholine (PC) vesicles. Lipid peroxidation was monitored by membrane fluidity changes assessed by electron paramagnetic resonance spectroscopy of a spin-labeled lipid and by the formation of thiobarbituric acid-reactive substances. When lipoperoxidation was initiated by the hydroxyl radical in erythrocyte ghost membranes, both 4-NC and α-tocopherol acted in a very efficient manner. However, lower activities were observed when lipoperoxidation was initiated by the peroxyl radical; and, in this case, the protective effect of α-tocopherol was lower than that of 4-NC. In egg PC vesicles, malondialdehyde formation indicated that 4-NC was effective against lipoperoxidation initiated by both AAPH and FeSO4/H2O2, whereas α-tocopherol was less efficient in protecting against lipoperoxidation by AAPH, and behaved as a pro-oxidant for FeSO4/H2O2. The DPPH (2,2-diphenyl-1-picrylhydrazyl) free-radical assay indicated that two free radicals were scavenged per 4-NC molecule, and one free radical was scavenged per α-tocopherol molecule. These data provide new insights into the antioxidant capacity of 4-NC, which may have therapeutic applications for formulations designed to protect the skin from sunlight irradiation. PMID:24068194

  15. Antioxidant effect of 4-nerolidylcatechol and α-tocopherol in erythrocyte ghost membranes and phospholipid bilayers

    International Nuclear Information System (INIS)

    Fernandes, K.S.; Silva, A.H.M.; Mendanha, S.A.; Rezende, K.R.; Alonso, A.

    2013-01-01

    4-Nerolidylcatechol (4-NC) is found in Pothomorphe umbellata root extracts and is reported to have a topical protective effect against UVB radiation-induced skin damage, toxicity in melanoma cell lines, and antimalarial activity. We report a comparative study of the antioxidant activity of 4-NC and α-tocopherol against lipid peroxidation initiated by two free radical-generating systems: 2,2′-azobis(2-aminopropane) hydrochloride (AAPH) and FeSO 4 /H 2 O 2 , in red blood cell ghost membranes and in egg phosphatidylcholine (PC) vesicles. Lipid peroxidation was monitored by membrane fluidity changes assessed by electron paramagnetic resonance spectroscopy of a spin-labeled lipid and by the formation of thiobarbituric acid-reactive substances. When lipoperoxidation was initiated by the hydroxyl radical in erythrocyte ghost membranes, both 4-NC and α-tocopherol acted in a very efficient manner. However, lower activities were observed when lipoperoxidation was initiated by the peroxyl radical; and, in this case, the protective effect of α-tocopherol was lower than that of 4-NC. In egg PC vesicles, malondialdehyde formation indicated that 4-NC was effective against lipoperoxidation initiated by both AAPH and FeSO 4 /H 2 O 2 , whereas α-tocopherol was less efficient in protecting against lipoperoxidation by AAPH, and behaved as a pro-oxidant for FeSO 4 /H 2 O 2 . The DPPH (2,2-diphenyl-1-picrylhydrazyl) free-radical assay indicated that two free radicals were scavenged per 4-NC molecule, and one free radical was scavenged per α-tocopherol molecule. These data provide new insights into the antioxidant capacity of 4-NC, which may have therapeutic applications for formulations designed to protect the skin from sunlight irradiation

  16. Antioxidant effect of 4-nerolidylcatechol and α-tocopherol in erythrocyte ghost membranes and phospholipid bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, K. S.; Silva, A. H.M.; Mendanha, S. A. [Instituto de Física, Universidade Federal de Goiás, Goiânia, GO (Brazil); Rezende, K. R. [Laboratório de Biofarmácia e Farmacocinética de Substâncias Bioativas, Faculdade de Farmácia, Universidade Federal de Goiás, Goiânia, GO (Brazil); Alonso, A. [Instituto de Física, Universidade Federal de Goiás, Goiânia, GO (Brazil)

    2013-09-06

    4-Nerolidylcatechol (4-NC) is found in Pothomorphe umbellata root extracts and is reported to have a topical protective effect against UVB radiation-induced skin damage, toxicity in melanoma cell lines, and antimalarial activity. We report a comparative study of the antioxidant activity of 4-NC and α-tocopherol against lipid peroxidation initiated by two free radical-generating systems: 2,2′-azobis(2-aminopropane) hydrochloride (AAPH) and FeSO{sub 4}/H{sub 2}O{sub 2}, in red blood cell ghost membranes and in egg phosphatidylcholine (PC) vesicles. Lipid peroxidation was monitored by membrane fluidity changes assessed by electron paramagnetic resonance spectroscopy of a spin-labeled lipid and by the formation of thiobarbituric acid-reactive substances. When lipoperoxidation was initiated by the hydroxyl radical in erythrocyte ghost membranes, both 4-NC and α-tocopherol acted in a very efficient manner. However, lower activities were observed when lipoperoxidation was initiated by the peroxyl radical; and, in this case, the protective effect of α-tocopherol was lower than that of 4-NC. In egg PC vesicles, malondialdehyde formation indicated that 4-NC was effective against lipoperoxidation initiated by both AAPH and FeSO{sub 4}/H{sub 2}O{sub 2}, whereas α-tocopherol was less efficient in protecting against lipoperoxidation by AAPH, and behaved as a pro-oxidant for FeSO{sub 4}/H{sub 2}O{sub 2}. The DPPH (2,2-diphenyl-1-picrylhydrazyl) free-radical assay indicated that two free radicals were scavenged per 4-NC molecule, and one free radical was scavenged per α-tocopherol molecule. These data provide new insights into the antioxidant capacity of 4-NC, which may have therapeutic applications for formulations designed to protect the skin from sunlight irradiation.

  17. Contribution of the Tyr-1 in Plantaricin149a to Disrupt Phospholipid Model Membranes

    Directory of Open Access Journals (Sweden)

    Georgina Tonarelli

    2013-06-01

    Full Text Available Plantaricin149a (Pln149a is a cationic antimicrobial peptide, which was suggested to cause membrane destabilization via the carpet mechanism. The mode of action proposed to this antimicrobial peptide describes the induction of an amphipathic α-helix from Ala7 to Lys20, while the N-terminus residues remain in a coil conformation after binding. To better investigate this assumption, the purpose of this study was to determine the contributions of the Tyr1 in Pln149a in the binding to model membranes to promote its destabilization. The Tyr to Ser substitution increased the dissociation constant (KD of the antimicrobial peptide from the liposomes (approximately three-fold higher, and decreased the enthalpy of binding to anionic vesicles from −17.2 kcal/mol to −10.2 kcal/mol. The peptide adsorption/incorporation into the negatively charged lipid vesicles was less effective with the Tyr1 substitution and peptide Pln149a perturbed the liposome integrity more than the analog, Pln149S. Taken together, the peptide-lipid interactions that govern the Pln149a antimicrobial activity are found not only in the amphipathic helix, but also in the N-terminus residues, which take part in enthalpic contributions due to the allocation at a lipid-aqueous interface.

  18. Finite element method (FEM) model of the mechanical stress on phospholipid membranes from shock waves produced in nanosecond electric pulses (nsEP)

    Science.gov (United States)

    Barnes, Ronald; Roth, Caleb C.; Shadaram, Mehdi; Beier, Hope; Ibey, Bennett L.

    2015-03-01

    The underlying mechanism(s) responsible for nanoporation of phospholipid membranes by nanosecond pulsed electric fields (nsEP) remains unknown. The passage of a high electric field through a conductive medium creates two primary contributing factors that may induce poration: the electric field interaction at the membrane and the shockwave produced from electrostriction of a polar submersion medium exposed to an electric field. Previous work has focused on the electric field interaction at the cell membrane, through such models as the transport lattice method. Our objective is to model the shock wave cell membrane interaction induced from the density perturbation formed at the rising edge of a high voltage pulse in a polar liquid resulting in a shock wave propagating away from the electrode toward the cell membrane. Utilizing previous data from cell membrane mechanical parameters, and nsEP generated shockwave parameters, an acoustic shock wave model based on the Helmholtz equation for sound pressure was developed and coupled to a cell membrane model with finite-element modeling in COMSOL. The acoustic structure interaction model was developed to illustrate the harmonic membrane displacements and stresses resulting from shockwave and membrane interaction based on Hooke's law. Poration is predicted by utilizing membrane mechanical breakdown parameters including cortical stress limits and hydrostatic pressure gradients.

  19. Cortical actin networks induce spatio-temporal confinement of phospholipids in the plasma membrane--a minimally invasive investigation by STED-FCS.

    Science.gov (United States)

    Andrade, Débora M; Clausen, Mathias P; Keller, Jan; Mueller, Veronika; Wu, Congying; Bear, James E; Hell, Stefan W; Lagerholm, B Christoffer; Eggeling, Christian

    2015-06-29

    Important discoveries in the last decades have changed our view of the plasma membrane organisation. Specifically, the cortical cytoskeleton has emerged as a key modulator of the lateral diffusion of membrane proteins. Cytoskeleton-dependent compartmentalised lipid diffusion has been proposed, but this concept remains controversial because this phenomenon has thus far only been observed with artefact-prone probes in combination with a single technique: single particle tracking. In this paper, we report the first direct observation of compartmentalised phospholipid diffusion in the plasma membrane of living cells using a minimally invasive, fluorescent dye labelled lipid analogue. These observations were made using optical STED nanoscopy in combination with fluorescence correlation spectroscopy (STED-FCS), a technique which allows the study of membrane dynamics on a sub-millisecond time-scale and with a spatial resolution of down to 40 nm. Specifically, we find that compartmentalised phospholipid diffusion depends on the cortical actin cytoskeleton, and that this constrained diffusion is directly dependent on the F-actin branching nucleator Arp2/3. These findings provide solid evidence that the Arp2/3-dependent cortical actin cytoskeleton plays a pivotal role in the dynamic organisation of the plasma membrane, potentially regulating fundamental cellular processes.

  20. Oxygen diffusion-concentration in phospholipidic model membranes. An ESR-saturation study

    International Nuclear Information System (INIS)

    Vachon, A.; Lecomte, C.; Berleur, F.

    1986-04-01

    Fully hydrated liposomes of dipalmitoyl-phosphatidylcholine were labelled with 5 (or 7, 10, 12, 16)-doxyl stearic acid at pH 6 and 8, and studied by the continuous wave ESR-saturation technique. The ESR spectral magnitude depends on the hyperfrequency power P and on both T 1 and T 2 relaxation times. Saturation, i.e. the non linearity of the spectral magnitude plotted versus √P can be quantified by a P1/2 parameter (power at which the signal is half as great as it would be without saturation). If we assume T 2 weakly modified by spin exchange between paramagnetic spin probe and oxygen in triplet state, P1/2 is inversely proportional to T 1 , and becomes a sensitive parameter to appreciate the oxygen transport (oxygen diffusion-concentration product) inside the bilayers. According to the DPPC bilayer phase transition diagrams, P1/2 (oxygen diffusion-concentration) is related to the thermodynamic state of the membrane. This technique provides further informations on a particular property of a radioprotective agent, cysteamine, which seems to inhibit spin-triplet exchange and hence maximizes T 1 (minimizes P1/2). Since radioprotective agents are known to act by scavenging radiation-induced free radicals and by inhibiting oxygen-dependent free radical processes, such a result may contribute to elucidate radioprotecting mechanisms

  1. Dynamics of fluid lines, sheets, filaments and membranes

    International Nuclear Information System (INIS)

    Coutris, N.

    1988-01-01

    We establish the dynamic equations of two types of fluid structures: 1) lines-filaments and 2) sheets-membranes. In the first part, we consider one-dimensional (line) and two-dimensional (sheet) fluid structures. The second part concerns the associated three- dimensional structures: filaments and membranes. In the third part, we establish the equations for thickened lines and thickened sheets. For that purpose, we introduce a thickness in the models of the first part. The fourth part concerns the thinning of the filament and the membrane. Then, by an asymptotic process, we deduce the corresponding equations from the equations of the second part in order to show the purely formal equivalence of the equations of the third and fourth parts. To obtain the equations, we make use of theorems whose proofs can be found in the appendices. The equations can be applied to many areas of interest: instabilities of liquid jets and liquid films, modelisation of interfaces between two different fluids as sheets or membranes, modelisation with the averaged equations over a cross section of single phase flows and two-phase flows in channels with a nonrectilinear axis such as bends or pump casings [fr

  2. 13C-labeled 18 : 2n-6 recovered in brush border membrane phospholipids short time after administration

    DEFF Research Database (Denmark)

    Vistisen, Bodil; Høy, Carl-Erik

    2004-01-01

    fatty acids in the two phospholipid pools. Minor effects on BBM-PC and BBM-PE fatty acid profiles (mole-%) were observed. The present study demonstrated for the first time incorporation of C-13-labeled 18:2n-6 into BBM-PC 2 hours and 6 hours after intragastric administration of L*L*L* or ML......*M. This emphasizes the influence of the dietary fatty acid on BBM fatty acid composition and the rapid incorporation of dietary long-chain fatty acids into intestinal enterocyte phospholipids. Medium-chain fatty acids in a single meal exert only a minor influence on the BBM phospholipid fatty acid profile....

  3. Direct interaction between EgFABP1, a fatty acid binding protein from Echinococcus granulosus, and phospholipid membranes.

    Directory of Open Access Journals (Sweden)

    Jorge L Porfido

    Full Text Available Growth and maintenance of hydatid cysts produced by Echinococcus granulosus have a high requirement for host lipids for biosynthetic processes, membrane building and possibly cellular and developmental signalling. This requires a high degree of lipid trafficking facilitated by lipid transporter proteins. Members of the fatty acid binding protein (FABP family have been identified in Echinococcus granulosus, one of which, EgFABP1 is expressed at the tegumental level in the protoscoleces, but it has also been described in both hydatid cyst fluid and secretions of protoscoleces. In spite of a considerable amount of structural and biophysical information on the FABPs in general, their specific functions remain mysterious.We have investigated the way in which EgFABP1 may interact with membranes using a variety of fluorescence-based techniques and artificial small unilamellar vesicles. We first found that bacterial recombinant EgFABP1 is loaded with fatty acids from the synthesising bacteria, and that fatty acid binding increases its resistance to proteinases, possibly due to subtle conformational changes induced on EgFABP1. By manipulating the composition of lipid vesicles and the ionic environment, we found that EgFABP1 interacts with membranes in a direct contact, collisional, manner to exchange ligand, involving both ionic and hydrophobic interactions. Moreover, we observed that the protein can compete with cytochrome c for association with the surface of small unilamellar vesicles (SUVs.This work constitutes a first approach to the understanding of protein-membrane interactions of EgFABP1. The results suggest that this protein may be actively involved in the exchange and transport of fatty acids between different membranes and cellular compartments within the parasite.

  4. Effects of phosphonium-based ionic liquids on phospholipid membranes studied by small-angle X-ray scattering

    Czech Academy of Sciences Publication Activity Database

    Kontro, I.; Svedström, K.; Duša, Filip; Ahvenainen, P.; Ruokonen, S. K.; Witos, J.; Wiedmer, S. K.

    2016-01-01

    Roč. 201, DEC (2016), s. 59-66 ISSN 0009-3084 Institutional support: RVO:68081715 Keywords : phospholipids * x-ray scattering Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.361, year: 2016

  5. Characterisation of the membrane affinity of an isoniazide peptide conjugate by tensiometry, atomic force microscopy and sum-frequency vibrational spectroscopy, using a phospholipid Langmuir monolayer model.

    Science.gov (United States)

    Hill, Katalin; Pénzes, Csanád Botond; Schnöller, Donát; Horváti, Kata; Bosze, Szilvia; Hudecz, Ferenc; Keszthelyi, Tamás; Kiss, Eva

    2010-10-07

    Tensiometry, sum-frequency vibrational spectroscopy, and atomic force microscopy were employed to assess the cell penetration ability of a peptide conjugate of the antituberculotic agent isoniazide. Isoniazide was conjugated to peptide (91)SEFAYGSFVRTVSLPV(106), a functional T-cell epitope of the immunodominant 16 kDa protein of Mycobacterium tuberculosis. As a simple but versatile model of the cell membrane a phospholipid Langmuir monolayer at the liquid/air interface was used. Changes induced in the structure of the phospholipid monolayer by injection of the peptide conjugate into the subphase were followed by tensiometry and sum-frequency vibrational spectroscopy. The drug penetrated lipid films were transferred to a solid support by the Langmuir-Blodgett technique, and their structures were characterized by atomic force microscopy. Peptide conjugation was found to strongly enhance the cell penetration ability of isoniazide.

  6. High-flux membrane separation using fluid skimming dominated convective fluid flow

    NARCIS (Netherlands)

    Dinther, van A.M.C.; Schroën, C.G.P.H.; Boom, R.M.

    2011-01-01

    We here report on the separation of yeast cells, with micro-engineered membranes having pores that are typically five times larger than the cells. The separation is due to neither shear-induced diffusion, nor initial lift, but to an effect similar to fluid skimming. The separation performance is

  7. Raised Vaginal Fluid Fibronectin Level Indicates Premature Rupture of Membrane

    Directory of Open Access Journals (Sweden)

    Amrita Bhowmik

    2012-07-01

    Full Text Available Background: Premature rupture of membrane (PROM is one of the common complications of pregnancy that has major impact on fetal and neonatal outcome. It is the commonest clinical event where a normal pregnancy becomes suddenly a high-risk one for mother and fetus or neonate. Objective: The study was undertaken to investigate whether raised fibronectin level in vaginal fluid may indicate premature rupture of membrane. Materials and Methods: This cross sectional study was conducted in the department of Obstetrics and Gynecology in Sir Salimullah Medical College & Mitford Hospital, Dhaka during the period of January 2006 to December 2007. A total of 114 pregnant women with gestational age 28th week up to 40th week were included. Sixty were PROM (Group I and 54 were non-PROM (Group II subjects. Fibronectin in vaginal fluid was measured by an immunochemical reaction by nephelometer. Statistical analysis was done by SPSS version 10.0. Results: The PROM patients had significantly higher concentration of fibronectin (225.77 ± 115.18 ng/mL compared to that in non-PROM subjects (8.04 ± 16.17 ng/mL (p < 0.001. Conclusion: It can be concluded that in cases of unequivocal rupture or intactness of the membranes, the result of the fibronectin test corresponds well with the clinical situation. So fibronectin is a sensitive test for detection of amniotic fluid in the vagina.

  8. Molecular phospholipid films on solid supports

    DEFF Research Database (Denmark)

    Czolkos, Ilja; Jesorka, Aldo; Orwar, Owe

    2011-01-01

    Phospholipid membranes are versatile structures for mimicking biological surfaces. Bilayer and monolayer membranes can be formed on solid supports, leading to enhanced stability and accessibility of the biomimetic molecular film. This has facilitated functional studies of membrane proteins and ai...

  9. Structural Interpretation of the Large Slowdown of Water Dynamics at Stacked Phospholipid Membranes for Decreasing Hydration Level: All-Atom Molecular Dynamics

    Directory of Open Access Journals (Sweden)

    Carles Calero

    2016-04-01

    Full Text Available Hydration water determines the stability and function of phospholipid membranes as well as the interaction of membranes with other molecules. Experiments and simulations have shown that water dynamics slows down dramatically as the hydration decreases, suggesting that the interfacial water that dominates the average dynamics at low hydration is slower than water away from the membrane. Here, based on all-atom molecular dynamics simulations, we provide an interpretation of the slowdown of interfacial water in terms of the structure and dynamics of water–water and water–lipid hydrogen bonds (HBs. We calculate the rotational and translational slowdown of the dynamics of water confined in stacked phospholipid membranes at different levels of hydration, from completely hydrated to poorly hydrated membranes. For all hydrations, we analyze the distribution of HBs and find that water–lipids HBs last longer than water–water HBs and that at low hydration most of the water is in the interior of the membrane. We also show that water–water HBs become more persistent as the hydration is lowered. We attribute this effect (i to HBs between water molecules that form, in turn, persistent HBs with lipids; (ii to the hindering of the H-bonding switching between water molecules due to the lower water density at the interface; and (iii to the higher probability of water–lipid HBs as the hydration decreases. Our interpretation of the large dynamic slowdown in water under dehydration is potentially relevant in understanding membrane biophysics at different hydration levels.

  10. Impact of oxidized phospholipids on the structural and dynamic organization of phospholipid membranes: a combined DSC and solid state NMR study

    Czech Academy of Sciences Publication Activity Database

    Wallgren, M.; Beranová, Lenka; Pham, Q. D.; Linh, K.; Lidman, M.; Procek, J.; Cyprych, K.; Kinnunen, P. K. J.; Hof, Martin; Gröbner, G.

    2013-01-01

    Roč. 161, DEC 2013 (2013), s. 499-513 ISSN 1359-6640 R&D Projects: GA AV ČR GEMEM/09/E006 Institutional support: RVO:61388955 Keywords : ACYL-CHAIN REVERSAL * MOLECULAR SIMULATIONS * LIPID-MEMBRANES Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.194, year: 2013

  11. Changes in the Fatty Acid Profile and Phospholipid Molecular Species Composition of Human Erythrocyte Membranes after Hybrid Palm and Extra Virgin Olive Oil Supplementation.

    Science.gov (United States)

    Pacetti, D; Gagliardi, R; Balzano, M; Frega, N G; Ojeda, M L; Borrero, M; Ruiz, A; Lucci, P

    2016-07-13

    This work aims to evaluate and compare, for the first time, the effects of extra virgin olive oil (EVOO) and hybrid palm oil (HPO) supplementation on the fatty acid profile and phospholipid (PL) molecular species composition of human erythrocyte membranes. Results supported the effectiveness of both HPO and EVOO supplementation (3 months, 25 mL/day) in decreasing the lipophilic index of erythrocytes with no significant differences between HPO and EVOO groups at month 3. On the other hand, the novel and rapid ultraperformance liquid chromatography-tandem mass spectrometry method used for PL analysis reveals an increase in the levels of phosphatidylcholine and phosphatidylethanolamine species esterified with polyunsaturated fatty acids. This work demonstrates the ability of both EVOO and HPO to increase the degree of unsaturation of erythrocyte membrane lipids with an improvement in membrane fluidity that could be associated with a lower risk of developing cardiovascular diseases.

  12. Impact of the β-Lactam Resistance Modifier (−-Epicatechin Gallate on the Non-Random Distribution of Phospholipids across the Cytoplasmic Membrane of Staphylococcus aureus

    Directory of Open Access Journals (Sweden)

    Helena Rosado

    2015-07-01

    Full Text Available The polyphenol (−-epicatechin gallate (ECg inserts into the cytoplasmic membrane (CM of methicillin-resistant Staphylococcus aureus (MRSA and reversibly abrogates resistance to β-lactam antibiotics. ECg elicits an increase in MRSA cell size and induces thickened cell walls. As ECg partially delocalizes penicillin-binding protein PBP2 from the septal division site, reduces PBP2 and PBP2a complexation and induces CM remodelling, we examined the impact of ECg membrane intercalation on phospholipid distribution across the CM and determined if ECg affects the equatorial, orthogonal mode of division. The major phospholipids of the staphylococcal CM, lysylphosphatidylglycerol (LPG, phosphatidylglycerol (PG, and cardiolipin (CL, were distributed in highly asymmetric fashion; 95%–97% of LPG was associated with the inner leaflet whereas PG (~90% and CL (~80% were found predominantly in the outer leaflet. ECg elicited small, significant changes in LPG distribution. Atomic force microscopy established that ECg-exposed cells divided in similar fashion to control bacteria, with a thickened band of encircling peptidoglycan representing the most recent plane of cell division, less distinct ribs indicative of previous sites of orthogonal division and concentric rings and “knobbles” representing stages of peptidoglycan remodelling during the cell cycle. Preservation of staphylococcal membrane lipid asymmetry and mode of division in sequential orthogonal planes appear key features of ECg-induced stress.

  13. Ethylene glycol as bore fluid for hollow fiber membrane preparation

    KAUST Repository

    Le, Ngoc Lieu

    2017-03-31

    We proposed the use of ethylene glycol and its mixture with water as bore fluid for the preparation of poly(ether imide) (PEI) hollow fiber membranes and compared their performance and morphology with membranes obtained with conventional coagulants (water and its mixture with the solvent N-methylpyrrolidone (NMP)). Thermodynamics and kinetics of the systems were investigated. Water and 1:1 water:EG mixtures lead to fast precipitation rates. Slow precipitation is observed for both pure EG and 9:1 NMP:water mixture, but the reasons for that are different. While low osmotic driving force leads to slow NMP and water transport when NMP:water is used, the high EG viscosity is the reason for the slow phase separation when EG is the bore fluid. The NMP:water mixture produces fibers with mixed sponge-like and finger-like structure with large pores in the inner and outer layers; and hence leading to a high water permeance and a high MWCO suitable for separation of large-sized proteins. As compared to NMP:water, using EG as bore fluid provides fibers with a finger-like bilayered structure and sponge-like layers near the surfaces, and hence contributing to the higher water permeance. It also induces small pores for better protein rejection.

  14. Ethylene glycol as bore fluid for hollow fiber membrane preparation

    KAUST Repository

    Le, Ngoc Lieu; Nunes, Suzana Pereira

    2017-01-01

    We proposed the use of ethylene glycol and its mixture with water as bore fluid for the preparation of poly(ether imide) (PEI) hollow fiber membranes and compared their performance and morphology with membranes obtained with conventional coagulants (water and its mixture with the solvent N-methylpyrrolidone (NMP)). Thermodynamics and kinetics of the systems were investigated. Water and 1:1 water:EG mixtures lead to fast precipitation rates. Slow precipitation is observed for both pure EG and 9:1 NMP:water mixture, but the reasons for that are different. While low osmotic driving force leads to slow NMP and water transport when NMP:water is used, the high EG viscosity is the reason for the slow phase separation when EG is the bore fluid. The NMP:water mixture produces fibers with mixed sponge-like and finger-like structure with large pores in the inner and outer layers; and hence leading to a high water permeance and a high MWCO suitable for separation of large-sized proteins. As compared to NMP:water, using EG as bore fluid provides fibers with a finger-like bilayered structure and sponge-like layers near the surfaces, and hence contributing to the higher water permeance. It also induces small pores for better protein rejection.

  15. Hamilton's equations for a fluid membrane: axial symmetry

    International Nuclear Information System (INIS)

    Capovilla, R; Guven, J; Rojas, E

    2005-01-01

    Consider a homogeneous fluid membrane, or vesicle, described by the Helfrich-Canham energy, quadratic in the mean curvature. When the membrane is axially symmetric, this energy can be viewed as an 'action' describing the motion of a particle; the contours of equilibrium geometries are identified with particle trajectories. A novel Hamiltonian formulation of the problem is presented which exhibits the following two features: (i) the second derivatives appearing in the action through the mean curvature are accommodated in a natural phase space and (ii) the intrinsic freedom associated with the choice of evolution parameter along the contour is preserved. As a result, the phase space involves momenta conjugate not only to the particle position but also to its velocity, and there are constraints on the phase space variables. This formulation provides the groundwork for a field theoretical generalization to arbitrary configurations, with the particle replaced by a loop in space

  16. Instabilities and diffusion in a hydrodynamic model of a fluid membrane coupled to a thin active fluid layer.

    Science.gov (United States)

    Sarkar, N; Basu, A

    2012-11-01

    We construct a coarse-grained effective two-dimensional (2d hydrodynamic theory as a theoretical model for a coupled system of a fluid membrane and a thin layer of a polar active fluid in its ordered state that is anchored to the membrane. We show that such a system is prone to generic instabilities through the interplay of nonequilibrium drive, polar order and membrane fluctuation. We use our model equations to calculate diffusion coefficients of an inclusion in the membrane and show that their values depend strongly on the system size, in contrast to their equilibrium values. Our work extends the work of S. Sankararaman and S. Ramaswamy (Phys. Rev. Lett., 102, 118107 (2009)) to a coupled system of a fluid membrane and an ordered active fluid layer. Our model is broadly inspired by and should be useful as a starting point for theoretical descriptions of the coupled dynamics of a cell membrane and a cortical actin layer anchored to it.

  17. Tropical to sub-polar gradient in phospholipid composition suggests adaptive tuning of biological membrane function in drosophilds

    Czech Academy of Sciences Publication Activity Database

    Slotsbo, S.; Sorensen, J. G.; Holmstrup, M.; Košťál, Vladimír; Kellermann, V.; Overgaard, J.

    2016-01-01

    Roč. 30, č. 5 (2016), s. 759-768 ISSN 0269-8463 Institutional support: RVO:60077344 Keywords : cold tolerance * Drosophila * phospholipid fatty acid composition Subject RIV: ED - Physiology Impact factor: 5.630, year: 2016 http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.12568/abstract

  18. Efficacy of bacterial bioremediation: Demonstration of complete incorporation of hydrocarbons into membrane phospholipids from Rhodococcus hydrocarbon degrading bacteria by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Rodgers, R.P.; Blumer, E.N.; Emmett, M.R.; Marshall, A.G.

    2000-02-01

    The authors present a method and example to establish complete incorporation of hydrocarbons into membrane phospholipids of putatively bioremediative bacteria. Bacteria are grown on minimal media containing a specified carbon source, either natural abundance or enriched. After extraction (but no other prior separation) of the membrane lipids, electrospray ionization yields a negative-ion FT-ICR mass spectrum containing prominent phospholipid parent ions. If {sup 13}C-enriched hydrocarbon incorporation is complete, then the mass of the parent ion will increase by n Da, in which n is the number of its constituent carbon atoms; moreover, the {sup 13}C isotopic distribution pattern will be reversed. The identities of the constituent fatty acids and polar headgroup are obtained by collisional dissociation (MS/MS), and their extent of {sup 13}C incorporation determined individually. The method is demonstrated for Rhodococcus rhodochrous (ATCC No. 53968), for which all 44 carbons of a representative phosphatidylinositol are shown to derive from the hydrocarbon source. Interestingly, although only C{sub 16} and C{sub 18} alkanes are provided in the growth medium, the bacteria synthesize uniformly enriched C16:0 and C19:0 fatty acids.

  19. Phospholipid-binding protein EhC2A mediates calcium-dependent translocation of transcription factor URE3-BP to the plasma membrane of Entamoeba histolytica.

    Science.gov (United States)

    Moreno, Heriberto; Linford, Alicia S; Gilchrist, Carol A; Petri, William A

    2010-05-01

    The Entamoeba histolytica upstream regulatory element 3-binding protein (URE3-BP) is a transcription factor that binds DNA in a Ca(2+)-inhibitable manner. The protein is located in both the nucleus and the cytoplasm but has also been found to be enriched in the plasma membrane of amebic trophozoites. We investigated the reason for the unusual localization of URE3-BP at the amebic plasma membrane. Here we identify and characterize a 22-kDa Ca(2+)-dependent binding partner of URE3-BP, EhC2A, a novel member of the C2-domain superfamily. Immunoprecipitations of URE3-BP and EhC2A showed that the proteins interact and that such interaction was enhanced in the presence of Ca(2+). Recombinant and native EhC2A bound phospholipid liposomes in a Ca(2+)-dependent manner, with half-maximal binding occurring at 3.4 muM free Ca(2+). A direct interaction between EhC2A and URE3-BP was demonstrated by the ability of recombinant EhC2A to recruit recombinant URE3-BP to phospholipid liposomes in a Ca(2+)-dependent manner. URE3-BP and EhC2A were observed to translocate to the amebic plasma membrane upon an increase in the intracellular Ca(2+) concentration of trophozoites, as revealed by subcellular fractionation and immunofluorescent staining. Short hairpin RNA-mediated knockdown of EhC2A protein expression significantly modulated the mRNA levels of URE3-BP-regulated transcripts. Based on these results, we propose a model for EhC2A-mediated regulation of the transcriptional activities of URE3-BP via Ca(2+)-dependent anchoring of the transcription factor to the amebic plasma membrane.

  20. Fluid Mechanics of the Vascular Basement Membrane in the Brain

    Science.gov (United States)

    Coloma, Mikhail; Hui, Jonathan; Chiarot, Paul; Huang, Peter; Carare, Roxana; McLeod, Kenneth; Schaffer, David

    2013-11-01

    Beta-amyloid is a normal product of brain metabolic function and is found within the interstitial fluid of the brain. Failure of the clearance of beta-amyloid from the aging brain leads to its accumulation within the walls of arteries and to Alzheimer's disease. The vascular basement membrane (VBM) within the walls of cerebral arteries surrounds the spirally arranged smooth muscle cells and represents an essential pathway for removal of beta-amyloid from the brain. This process fails with the stiffening of arterial walls associated with aging. In this study we hypothesize that the deformation of the VBM associated with arterial pulsations drives the interstitial fluid to drain in the direction opposite of the arterial blood flow. This hypothesis is theoretically investigated by modeling the VBM as a thin, coaxial, fluid-filled porous medium surrounding a periodically deforming cylindrical tube. Flow and boundary conditions required to achieve such a backward clearance are derived through a control volume analysis of mass, momentum, and energy.

  1. Competing intermolecular interactions of artemisinin-type agents and aspirin with membrane phospholipids: Combined model mass spectrometry and quantum-chemical study

    Energy Technology Data Exchange (ETDEWEB)

    Pashynska, Vlada, E-mail: vlada@vl.kharkov.ua [B.Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine, Lenin Ave., 47, 61103 Kharkov (Ukraine); Stepanian, Stepan [B.Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine, Lenin Ave., 47, 61103 Kharkov (Ukraine); Gömöry, Agnes; Vekey, Karoly [Institute of Organic Chemistry of Research Centre for Natural Sciences of the Hungarian Academy of Sciences, Magyar tudosok korutja, 2, Budapest H-1117 (Hungary); Adamowicz, Ludwik [University of Arizona, Department of Chemistry and Biochemistry, Tucson, AZ 85721 (United States)

    2015-07-09

    Highlights: • Competitive binding of artemisinin agents and aspirin with phospholipids is shown. • Complexation between the antimalarial drugs and aspirin molecules is also found. • Energetically favorable structures of the model complexes are identified by DFT. • Membranotropic activity of the studied drugs can be modified under joint usage. - Abstract: Study of intermolecular interactions of antimalarial artemisinin-type drugs and aspirin with membrane phospholipids is important in term of elucidation of the drugs activity modification under their joint usage. Combined experimental and computational study of the interaction of dihydroartemisinin, α-artemether, and artesunate with aspirin (ASP) and dipalmitoylphosphatidylcholine (DPPC) is performed by electrospray ionization (ESI) mass spectrometry and by DFT B3LYP/aug-cc-pVDZ methods. The results of the ESI investigation of systems containing artemisinin-type agent, ASP and DPPC, reveal a competition between the antimalarial agents and ASP for binding with DPPC molecules. The complexation between the antimalarial drugs and ASP is also found. Observed phenomena suggest that membranotropic activity of artemisin-type agents and aspirin is modified under their combined usage. To elucidate structure-energy characteristics of the non-covalent complexes studied the model DFT calculations are performed for dihydroartemisinin · ASP complex and complexes of the each drug with phosphatidylcholine head of DPPC in neutral and cationized forms.

  2. Competing intermolecular interactions of artemisinin-type agents and aspirin with membrane phospholipids: Combined model mass spectrometry and quantum-chemical study

    International Nuclear Information System (INIS)

    Pashynska, Vlada; Stepanian, Stepan; Gömöry, Agnes; Vekey, Karoly; Adamowicz, Ludwik

    2015-01-01

    Highlights: • Competitive binding of artemisinin agents and aspirin with phospholipids is shown. • Complexation between the antimalarial drugs and aspirin molecules is also found. • Energetically favorable structures of the model complexes are identified by DFT. • Membranotropic activity of the studied drugs can be modified under joint usage. - Abstract: Study of intermolecular interactions of antimalarial artemisinin-type drugs and aspirin with membrane phospholipids is important in term of elucidation of the drugs activity modification under their joint usage. Combined experimental and computational study of the interaction of dihydroartemisinin, α-artemether, and artesunate with aspirin (ASP) and dipalmitoylphosphatidylcholine (DPPC) is performed by electrospray ionization (ESI) mass spectrometry and by DFT B3LYP/aug-cc-pVDZ methods. The results of the ESI investigation of systems containing artemisinin-type agent, ASP and DPPC, reveal a competition between the antimalarial agents and ASP for binding with DPPC molecules. The complexation between the antimalarial drugs and ASP is also found. Observed phenomena suggest that membranotropic activity of artemisin-type agents and aspirin is modified under their combined usage. To elucidate structure-energy characteristics of the non-covalent complexes studied the model DFT calculations are performed for dihydroartemisinin · ASP complex and complexes of the each drug with phosphatidylcholine head of DPPC in neutral and cationized forms

  3. Dicarboxylic phospholipids and irradiated biomembranes

    International Nuclear Information System (INIS)

    Dousset, Nicole.

    1977-01-01

    It was decided to study the effects of ionizing radiations on biomembranes, with special reference to erythrocytes and liver microsomes representing two kinds of membrane very common in nature. Diacid phospholipids were observed at these membranes and the results are reported in part one of this work. It appeared essential to examine as far as possible the metabolism, in vitro and in animals, of these diacids and to find out whether certain harmful effects of radiations on the proteins (membrane permeability changes and enzyme inactivation) could be due to the action of these newly formed compounds. The study of acid compounds formed under irradiation was limited to nonanal-9-oic acid and azelaic acid. Part two deals with the incorporation of acid and diacid compounds into lipids and the effects of diacid phospholipids on the membrane permeability. A chapter is devoted to the changes in certain enzyme activities brought about by diacid phospholipids [fr

  4. Hamilton's equations for a fluid membrane

    Energy Technology Data Exchange (ETDEWEB)

    Capovilla, R [Departamento de Fisica, Centro de Investigacion y de Estudios Avanzados, Apdo. Postal 14-740, 07000 Mexico, DF (Mexico); Guven, J [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Apdo. Postal 70-543, 04510 Mexico, DF (Mexico); Rojas, E [Facultad de Fisica e Inteligencia Artificial, Universidad Veracruzana, 91000 Xalapa, Veracruz (Mexico)

    2005-10-14

    Consider a homogeneous fluid membrane described by the Helfrich-Canham energy, quadratic in the mean curvature of the membrane surface. The shape equation that determines equilibrium configurations is fourth order in derivatives and cubic in the mean curvature. We introduce a Hamiltonian formulation of this equation which dismantles it into a set of coupled first-order equations. This involves interpreting the Helfrich-Canham energy as an action; equilibrium surfaces are generated by the evolution of space curves. Two features complicate the implementation of a Hamiltonian framework. (i) The action involves second derivatives. This requires treating the velocity as a phase-space variable and the introduction of its conjugate momentum. The canonical Hamiltonian is constructed on this phase space. (ii) The action possesses a local symmetry-reparametrization invariance. The two labels we use to parametrize points on the surface are themselves physically irrelevant. This symmetry implies primary constraints, one for each label, that need to be implemented within the Hamiltonian. The two Lagrange multipliers associated with these constraints are identified as the components of the acceleration tangential to the surface. The conservation of the primary constraints implies two secondary constraints, fixing the tangential components of the momentum conjugate to the position. Hamilton's equations are derived and the appropriate initial conditions on the phase-space variables are identified. Finally, it is shown how the shape equation can be reconstructed from these equations.

  5. Cell signalling and phospholipid metabolism

    Energy Technology Data Exchange (ETDEWEB)

    Boss, W.F.

    1990-01-01

    These studies explored whether phosphoinositide (PI) has a role in plants analogous to its role in animal cells. Although no parallel activity of PI in signal transduction was found in plant cells, activity of inositol phospholipid kinase was found to be modulated by light and by cell wall degrading enzymes. These studies indicate a major role for inositol phospholipids in plant growth and development as membrane effectors but not as a source of second messengers.

  6. Effects of acclimation temperature on thermal tolerance and membrane phospholipid composition in the fruit fly Drosophila melanogaster

    DEFF Research Database (Denmark)

    Overgaard, Johannes; Tomcala, Ales; Sørensen, Jesper G

    2008-01-01

    and the composition of membrane GPLs in adult Drosophila melanogaster. Long-term cold survival was significantly improved by low acclimation temperature. After 60h at 0 degrees C, more than 80% of the 15 degrees C-acclimated flies survived while none of the 25 degrees C-acclimated flies survived. Cold shock tolerance...... acclimation temperature and correlated with the changes in GPL composition in membranes of adult D. melanogaster. Udgivelsesdato: 2008-Mar...

  7. Lysosomotropic cationic amphiphilic drugs inhibit adipocyte differentiation in 3T3-L1K cells via accumulation in cells and phospholipid membranes, and inhibition of autophagy.

    Science.gov (United States)

    Kagebeck, Patrik; Nikiforova, Violetta; Brunken, Lars; Easwaranathan, Arrabi; Ruegg, Joelle; Cotgreave, Ian; Munic Kos, Vesna

    2018-04-05

    Some cationic amphiphilic drugs (CADs) have been individually reported to interfere with the differentiation of immune system cells, such as macrophages and dendritic cells. To investigate the possible generic nature of this process, in this study we aimed to see whether these drugs are capable of interfering with the differentiation of adipocytes. Further, we investigated whether this feature might be connected to the lysosomotropic character of these drugs, and their disturbance of intracellular membrane trafficking rather than to the individual pharmacologic properties of each drug. Thus, for the selected set of compounds consisting of seven structurally and pharmacologically diverse CADs and three non-CAD controls we have measured the impact on differentiation of 3T3-L1K murine preadipocytes to adipocytes. We conclude that CADs indeed inhibit adipocyte differentiation, as shown morphologically, at the level of lipid droplet formation and on the expression of genetic markers of adipocytes. Furthermore, the intensity of this inhibitory effect was found to strongly positively correlate with the extent of drug accumulation in adipocytes, with their affinity for phospholipid membranes, as well as with their ability to induce phospholipidosis and inhibit autophagy. Copyright © 2018 Elsevier B.V. All rights reserved.

  8. Absence of first-order unbinding transitions of fluid and polymerized membranes

    Science.gov (United States)

    Grotehans, Stefan; Lipowsky, Reinhard

    1990-01-01

    Unbinding transitions of fluid and polymerized membranes are studied by renormalization-group (RG) methods. Two different RG schemes are used and found to give rather consistent results. The fixed-point structure of both RG's exhibits a complex behavior as a function of the decay exponent tau for the fluctuation-induced interaction of the membranes. For tau greater than tau(S2) interacting membranes can undergo first-order transitions even in the strong-fluctuation regime. These estimates for tau(S2) imply, however, that both fluid and polymerized membranes unbind in a continuous way in the absence of lateral tension.

  9. Molecular aspects of the interaction between MasonPfizer monkey virus matrix protein and artificial phospholipid membrane

    Czech Academy of Sciences Publication Activity Database

    Junková, P.; Prchal, J.; Spiwok, V.; Pleskot, Roman; Kadlec, J.; Krásný, Libor; Hynek, R.; Hrabal, R.; Ruml, T.

    2016-01-01

    Roč. 84, č. 11 (2016), s. 1717-1727 ISSN 0887-3585 Institutional support: RVO:61389030 ; RVO:61388971 Keywords : d-type retrovirus * force-field * nucleotide-sequence * myristate exposure * plasma-membrane * rhesus monkey Subject RIV: EB - Genetics ; Molecular Biology; EE - Microbiology, Virology (MBU-M) Impact factor: 2.289, year: 2016

  10. Molecular aspects of the interaction between Mason-Pfizer monkey virus matrix protein and artificial phospholipid membrane

    Czech Academy of Sciences Publication Activity Database

    Junková, P.; Prchal, J.; Spiwok, V.; Pleskot, Roman; Kadlec, Jan; Krásný, L.; Hynek, R.; Hrabal, R.; Ruml, T.

    2016-01-01

    Roč. 84, č. 11 (2016), s. 1717-1727 ISSN 0887-3585 Institutional support: RVO:61388963 Keywords : covalent labelling * mass spectrometry * multiscale molecular dynamics * protein-membrane interaction * phosphatidylinositol-(4,5)-bisphosphate * liposomes Subject RIV: CE - Biochemistry Impact factor: 2.289, year: 2016

  11. Free fatty acids and esters can be immobilized by receptor rich membranes from torpedo marmorata but not phospholipid acyl chains

    NARCIS (Netherlands)

    Rousselet, A.; Devaux, P.F.; Wirtz, K.W.A.

    1979-01-01

    A long chain spin labeled fatty acid and the corresponding ester have been introduced into receptor rich membranes from Torpedo Marmorata. Superimposed to a mobile component, typical of the lipid phase, a strongly immobilized component is seen on the ESR spectra, both at low temperature (−4°C) and

  12. Kinetics of the lamellar gel-fluid transition in phosphatidylcholine membranes in the presence of sugars

    Energy Technology Data Exchange (ETDEWEB)

    Lenné, Thomas; Garvey, Christopher J.; Koster, Karen L.; Bryant, Gary [ANSTO; (USD); (RMIT)

    2014-09-24

    Phase diagrams are presented for dipalmitoylphosphatidylcholine (DPPC) in the presence of sugars (sucrose) over a wide range of relative humidities (RHs). The phase information presented here, determined by small angle X-ray scattering (SAXS), is shown to be consistent with previous results achieved by differential scanning calorimetry (DSC). Both techniques show a significant effect of sucrose concentration on the phase behaviour of this phospholipid bilayer. An experimental investigation into the effect of sugars on the kinetic behaviour of the gel to fluid transition is also presented showing that increasing the sugar content appears to slightly increase the rate at which the transition occurs.

  13. Kinetics of the lamellar gel-fluid transition in phosphatidylcholine membranes in the presence of sugars

    Energy Technology Data Exchange (ETDEWEB)

    Lenné, Thomas; Garvey, Christopher J; Koster, Karen L; Bryant, Gary [ANSTO; (USD); (RMIT)

    2010-08-04

    Phase diagrams are presented for dipalmitoylphosphatidylcholine (DPPC) in the presence of sugars (sucrose) over a wide range of relative humidities (RHs). The phase information presented here, determined by small angle X-ray scattering (SAXS), is shown to be consistent with previous results achieved by differential scanning calorimetry (DSC). Both techniques show a significant effect of sucrose concentration on the phase behaviour of this phospholipid bilayer. An experimental investigation into the effect of sugars on the kinetic behaviour of the gel to fluid transition is also presented showing that increasing the sugar content appears to slightly increase the rate at which the transition occurs.

  14. A general theory of non-equilibrium dynamics of lipid-protein fluid membranes

    DEFF Research Database (Denmark)

    Lomholt, Michael Andersen; Hansen, Per Lyngs; Miao, L.

    2005-01-01

    We present a general and systematic theory of non-equilibrium dynamics of multi-component fluid membranes, in general, and membranes containing transmembrane proteins, in particular. Developed based on a minimal number of principles of statistical physics and designed to be a meso...

  15. DSC and EPR investigations on effects of cholesterol component on molecular interactions between paclitaxel and phospholipid within lipid bilayer membrane.

    Science.gov (United States)

    Zhao, Lingyun; Feng, Si-Shen; Kocherginsky, Nikolai; Kostetski, Iouri

    2007-06-29

    Differential scanning calorimetry (DSC) and electron paramagnetic resonance spectroscopy (EPR) were applied to investigate effects of cholesterol component on molecular interactions between paclitaxel, which is one of the best antineoplastic agents found from nature, and dipalmitoylphosphatidylcholine (DPPC) within lipid bilayer vesicles (liposomes), which could also be used as a model cell membrane. DSC analysis showed that incorporation of paclitaxel into the DPPC bilayer causes a reduction in the cooperativity of bilayer phase transition, leading to a looser and more flexible bilayer structure. Including cholesterol component in the DPPC/paclitaxel mixed bilayer can facilitate the molecular interaction between paclitaxel and lipid and make the tertiary system more stable. EPR analysis demonstrated that both of paclitaxel and cholesterol have fluidization effect on the DPPC bilayer membranes although cholesterol has more significant effect than paclitaxel does. The reduction kinetics of nitroxides by ascorbic acid showed that paclitaxel can inhibit the reaction by blocking the diffusion of either the ascorbic acid or nitroxide molecules since the reaction is tested to be a first order one. Cholesterol can remarkably increase the reduction reaction speed. This research may provide useful information for optimizing liposomal formulation of the drug as well as for understanding the pharmacology of paclitaxel.

  16. Effect of Ca2+ on the morphology of mixed DPPC-DOPS supported phospholipid bilayers

    NARCIS (Netherlands)

    Reviakine, [No Value; Simon, A; Brisson, A

    2000-01-01

    The morphology of supported phospholipid bilayers (SPBs) containing mixtures of phospholipids in gel (dipalmitoyl phosphatidylcholine, DPPC) and fluid (dioleoyl phosphatidylserine (DOPS) or -choline (DOPC)) states at room temperature was investigated by atomic force microscopy (AFM). Fluid-gel phase

  17. Monte Carlo simulations of the distributions of intra- and extra-vesicular ions and membrane associated charges in hybrid liposomes composed of negatively charged tetraether and zwitterionic diester phospholipids

    Directory of Open Access Journals (Sweden)

    István P. Sugár

    2017-04-01

    Full Text Available Here, we model a negatively charged lipid vesicle, composed of a mixture of bipolar tetraether and diester (or diether phospholipid molecules, by a spherical shell that has zero ion permeability. We take into consideration all the charge-charge interactions between intra-vesicular ions, extra-vesicular ions, and membrane lipid associated charges. Monte Carlo simulations result in homogeneous and double-exponential ion distribution, respectively, in the intra- and extra-vesicular space. The extra-vesicular ion concentration close to the membrane surface is proportional to the total amount of the membrane charges (Nm and is independent of the partitioning of the membrane charges between the outer (Nom and inner membrane (Nim surface. This result shows that one should not disregard the effect of the charges on the inner membrane surface when calculating the ion distributions around a charged vesicle. If the partitioning of the membrane charges is not restricted (i.e., lipid flip-flop is allowed, then at different Nm, the Nom/Nim ratio remains constant and the value of Nom/Nim, as a consequence of the interaction between every charges of the model, is close to, but significantly higher than, the ratio of the outer to the inner surface area of the membrane. These results indicate that the amount and the orientation of the negatively-charged tetraether lipids in the membrane are important determinants of membrane properties in tetraether/zwitterionic diester phospholipid liposomes. Finally we compared the results of our discrete charge model and continuous models based on the solutions of the Poisson-Boltzmann equation and pointed out qualitative similarities and sometimes major quantitative differences between these two types of models.

  18. Herpes simplex virus 1 induces de novo phospholipid synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Sutter, Esther [Electron Microscopy, Institute of Veterinary Anatomy, University of Zuerich (Switzerland); Oliveira, Anna Paula de; Tobler, Kurt [Electron microscopy, Institute of Virology, University of Zuerich (Switzerland); Schraner, Elisabeth M. [Electron Microscopy, Institute of Veterinary Anatomy, University of Zuerich (Switzerland); Sonda, Sabrina [Institute of Parasitology, University of Zuerich (Switzerland); Kaech, Andres [Center for Microscopy and Image Analysis, University of Zuerich (Switzerland); Lucas, Miriam S. [Electron Microscopy ETH Zuerich (EMEZ), Swiss Federal Institute of Technology, Zuerich (Switzerland); Ackermann, Mathias [Electron microscopy, Institute of Virology, University of Zuerich (Switzerland); Wild, Peter, E-mail: pewild@access.uzh.ch [Electron Microscopy, Institute of Veterinary Anatomy, University of Zuerich (Switzerland)

    2012-08-01

    Herpes simplex virus type 1 capsids bud at nuclear membranes and Golgi membranes acquiring an envelope composed of phospholipids. Hence, we measured incorporation of phospholipid precursors into these membranes, and quantified changes in size of cellular compartments by morphometric analysis. Incorporation of [{sup 3}H]-choline into both nuclear and cytoplasmic membranes was significantly enhanced upon infection. [{sup 3}H]-choline was also part of isolated virions even grown in the presence of brefeldin A. Nuclei expanded early in infection. The Golgi complex and vacuoles increased substantially whereas the endoplasmic reticulum enlarged only temporarily. The data suggest that HSV-1 stimulates phospholipid synthesis, and that de novo synthesized phospholipids are inserted into nuclear and cytoplasmic membranes to i) maintain membrane integrity in the course of nuclear and cellular expansion, ii) to supply membrane constituents for envelopment of capsids by budding at nuclear membranes and Golgi membranes, and iii) to provide membranes for formation of transport vacuoles.

  19. The homeodomain derived peptide Penetratin induces curvature of fluid membrane domains.

    Directory of Open Access Journals (Sweden)

    Antonin Lamazière

    Full Text Available BACKGROUND: Protein membrane transduction domains that are able to cross the plasma membrane are present in several transcription factors, such as the homeodomain proteins and the viral proteins such as Tat of HIV-1. Their discovery resulted in both new concepts on the cell communication during development, and the conception of cell penetrating peptide vectors for internalisation of active molecules into cells. A promising cell penetrating peptide is Penetratin, which crosses the cell membranes by a receptor and metabolic energy-independent mechanism. Recent works have claimed that Penetratin and similar peptides are internalized by endocytosis, but other endocytosis-independent mechanisms have been proposed. Endosomes or plasma membranes crossing mechanisms are not well understood. Previously, we have shown that basic peptides induce membrane invaginations suggesting a new mechanism for uptake, "physical endocytosis". METHODOLOGY/PRINCIPAL FINDINGS: Herein, we investigate the role of membrane lipid phases on Penetratin induced membrane deformations (liquid ordered such as in "raft" microdomains versus disordered fluid "non-raft" domains in membrane models. Experimental data show that zwitterionic lipid headgroups take part in the interaction with Penetratin suggesting that the external leaflet lipids of cells plasma membrane are competent for peptide interaction in the absence of net negative charges. NMR and X-ray diffraction data show that the membrane perturbations (tubulation and vesiculation are associated with an increase in membrane negative curvature. These effects on curvature were observed in the liquid disordered but not in the liquid ordered (raft-like membrane domains. CONCLUSIONS/SIGNIFICANCE: The better understanding of the internalisation mechanisms of protein transduction domains will help both the understanding of the mechanisms of cell communication and the development of potential therapeutic molecular vectors. Here we

  20. Fluid-membrane tethers: minimal surfaces and elastic boundary layers.

    Science.gov (United States)

    Powers, Thomas R; Huber, Greg; Goldstein, Raymond E

    2002-04-01

    Thin cylindrical tethers are common lipid bilayer membrane structures, arising in situations ranging from micromanipulation experiments on artificial vesicles to the dynamic structure of the Golgi apparatus. We study the shape and formation of a tether in terms of the classical soap-film problem, which is applied to the case of a membrane disk under tension subject to a point force. A tether forms from the elastic boundary layer near the point of application of the force, for sufficiently large displacement. Analytic results for various aspects of the membrane shape are given.

  1. Evaluation of Ultrafiltration Performance for Phospholipid Separation

    Science.gov (United States)

    Aryanti, N.; Wardhani, D. H.; Maulana, Z. S.; Roberto, D.

    2017-11-01

    Ultrafiltration membrane for degumming of crude palm oil has been applied as an alternative method since the membrane process required less procedure than the conventional degumming. This research focused on the examination of ultrafiltration performance for phospholipid separation from model crude palm oil degumming. Specifically, profile flux and rejection, as well as blocking mechanism, were investigated. Feed consisting of Refined Crude Palm Oil - Isopropanol - Lecithin mixtures were represented as crude palm oil degumming. Lecithin was denoted a phospholipid component, and the concentrations of lecithin in feed were varied to 0.1%, 0.2%, and 0.3%. The concentration of phospholipid was determined as phosphor content. At the concentration of lecithin in feed representing phospholipid concentration of 8,45 mg/kg, 8,45 mg/kg, 24,87 mg/kg and 57,58 mg/kg, respectively. Flux profiles confirmed that there was a flux decline during filtration. In addition, the lecithin concentrations do not significantly effect on further flux decline. Rejection characteristic and phospholipid concentration in the permeate showed that the phospholipid rejections by ultrafiltration were in the range of 23-79,5% representing permeate’s phospholipid concentration of 1,73 - 44,25 mg/kg. Evaluation of fouling mechanism by Hermia’s blocking model confirmed that the standard blocking is the dominant mechanism in the ultrafiltration of lecithin mixture.

  2. Cell signalling and phospholipid metabolism. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Boss, W.F.

    1990-12-31

    These studies explored whether phosphoinositide (PI) has a role in plants analogous to its role in animal cells. Although no parallel activity of PI in signal transduction was found in plant cells, activity of inositol phospholipid kinase was found to be modulated by light and by cell wall degrading enzymes. These studies indicate a major role for inositol phospholipids in plant growth and development as membrane effectors but not as a source of second messengers.

  3. Electrochemically deposited and etched membranes with precisely sized micropores for biological fluids microfiltration

    International Nuclear Information System (INIS)

    Hamzah, A A; Zainal Abidin, H E; Yeop Majlis, B; Mohd Nor, M; Ismardi, A; Sugandi, G; Tiong, T Y; Dee, C F; Yunas, J

    2013-01-01

    This paper presents simple and economical, yet reliable techniques to fabricate a micro-fluidic filter for MEMS lab-on-chip (LoC) applications. The microporous filter is a crucial component in a MEMS LoC system. Microsized components and contaminants in biological fluids are selectively filtered using copper and silicon membranes with precisely controlled microsized pores. Two techniques were explored in microporous membrane fabrication, namely copper electroplating and electrochemical etching (ECE) of silicon. In the first technique, a copper membrane with evenly distributed micropores was fabricated by electroplating the copper layer on the silicon nitride membrane, which was later removed to leave the freestanding microporous membrane structure. The second approach involves the thinning of bulk silicon down to a few micrometers thick using KOH and etching the resulting silicon membrane in 5% HF by ECE to create micropores. Upon testing with nanoparticles of various sizes, it was observed that electroplated copper membrane passes nanoparticles up to 200 nm wide, while porous silicon membrane passes nanoparticles up to 380 nm in size. Due to process compatibility, simplicity, and low-cost fabrication, electroplated copper and porous silicon membranes enable synchronized microfilter fabrication and integration into the MEMS LoC system. (paper)

  4. Drug binding and mobility relating to the thermal fluctuation in fluid lipid membranes

    Science.gov (United States)

    Okamura, Emiko; Yoshii, Noriyuki

    2008-12-01

    Drug binding and mobility in fluid lipid bilayer membranes are quantified in situ by using the multinuclear solution NMR combined with the pulsed-field-gradient technique. One-dimensional and pulsed-field-gradient F19 and H1 NMR signals of an anticancer drug, 5-fluorouracil (5FU) are analyzed at 283-313 K in the presence of large unilamellar vesicles (LUVs) of egg phosphatidylcholine (EPC) as model cell membranes. The simultaneous observation of the membrane-bound and free 5FU signals enables to quantify in what amount of 5FU is bound to the membrane and how fast 5FU is moving within the membrane in relation to the thermal fluctuation of the soft, fluid environment. It is shown that the mobility of membrane-bound 5FU is slowed down by almost two orders of magnitude and similar to the lipid movement in the membrane, the movement closely related to the intramembrane fluidity. The mobility of 5FU and EPC is, however, not similar at 313 K; the 5FU movement is enhanced in the membrane as a result of the loose binding of 5FU in the lipid matrices. The membrane-bound fraction of 5FU is ˜0.1 and almost unaltered over the temperature range examined. It is also independent of the 5FU concentration from 2 to 30 mM with respect to the 40-50 mM LUV. The free energy of the 5FU binding is estimated at -4 to -2 kJ/mol, the magnitude always close to the thermal fluctuation, 2.4-2.6 kJ/mol.

  5. Alboserpin, a Factor Xa Inhibitor from the Mosquito Vector of Yellow Fever, Binds Heparin and Membrane Phospholipids and Exhibits Antithrombotic Activity

    Czech Academy of Sciences Publication Activity Database

    Calvo, E.; Mizurini, D.M.; Sa-Nunes, A.; Ribeiro, J.M.C.; Andersen, J. F.; Mans, B.J.; Monteiro, R.Q.; Kotsyfakis, Michalis; Francischetti, I.M.B.

    2011-01-01

    Roč. 286, č. 32 (2011), 27998-28010 ISSN 0021-9258 Institutional research plan: CEZ:AV0Z60220518 Keywords : serpin * mosquito * Aedes albopictus * phospholipids * Factor Xa * heparin * binding affinity * coagulation * thrombus * bleeding Subject RIV: GJ - Animal Vermins ; Diseases, Veterinary Medicine Impact factor: 4.773, year: 2011

  6. Vascular basement membranes as pathways for the passage of fluid into and out of the brain.

    Science.gov (United States)

    Morris, Alan W J; Sharp, Matthew MacGregor; Albargothy, Nazira J; Fernandes, Rute; Hawkes, Cheryl A; Verma, Ajay; Weller, Roy O; Carare, Roxana O

    2016-05-01

    In the absence of conventional lymphatics, drainage of interstitial fluid and solutes from the brain parenchyma to cervical lymph nodes is along basement membranes in the walls of cerebral capillaries and tunica media of arteries. Perivascular pathways are also involved in the entry of CSF into the brain by the convective influx/glymphatic system. The objective of this study is to differentiate the cerebral vascular basement membrane pathways by which fluid passes out of the brain from the pathway by which CSF enters the brain. Experiment 1: 0.5 µl of soluble biotinylated or fluorescent Aβ, or 1 µl 15 nm gold nanoparticles was injected into the mouse hippocampus and their distributions determined at 5 min by transmission electron microscopy. Aβ was distributed within the extracellular spaces of the hippocampus and within basement membranes of capillaries and tunica media of arteries. Nanoparticles did not enter capillary basement membranes from the extracellular spaces. Experiment 2: 2 µl of 15 nm nanoparticles were injected into mouse CSF. Within 5 min, groups of nanoparticles were present in the pial-glial basement membrane on the outer aspect of cortical arteries between the investing layer of pia mater and the glia limitans. The results of this study and previous research suggest that cerebral vascular basement membranes form the pathways by which fluid passes into and out of the brain but that different basement membrane layers are involved. The significance of these findings for neuroimmunology, Alzheimer's disease, drug delivery to the brain and the concept of the Virchow-Robin space are discussed.

  7. Development of modifications to the material point method for the simulation of thin membranes, compressible fluids, and their interactions

    Energy Technology Data Exchange (ETDEWEB)

    York, A.R. II [Sandia National Labs., Albuquerque, NM (United States). Engineering and Process Dept.

    1997-07-01

    The material point method (MPM) is an evolution of the particle in cell method where Lagrangian particles or material points are used to discretize the volume of a material. The particles carry properties such as mass, velocity, stress, and strain and move through a Eulerian or spatial mesh. The momentum equation is solved on the Eulerian mesh. Modifications to the material point method are developed that allow the simulation of thin membranes, compressible fluids, and their dynamic interactions. A single layer of material points through the thickness is used to represent a membrane. The constitutive equation for the membrane is applied in the local coordinate system of each material point. Validation problems are presented and numerical convergence is demonstrated. Fluid simulation is achieved by implementing a constitutive equation for a compressible, viscous, Newtonian fluid and by solution of the energy equation. The fluid formulation is validated by simulating a traveling shock wave in a compressible fluid. Interactions of the fluid and membrane are handled naturally with the method. The fluid and membrane communicate through the Eulerian grid on which forces are calculated due to the fluid and membrane stress states. Validation problems include simulating a projectile impacting an inflated airbag. In some impact simulations with the MPM, bodies may tend to stick together when separating. Several algorithms are proposed and tested that allow bodies to separate from each other after impact. In addition, several methods are investigated to determine the local coordinate system of a membrane material point without relying upon connectivity data.

  8. Computational fluid dynamics simulations of membrane filtration process adapted for water treatment of aerated sewage lagoons.

    Science.gov (United States)

    Cano, Grégory; Mouahid, Adil; Carretier, Emilie; Guasp, Pascal; Dhaler, Didier; Castelas, Bernard; Moulin, Philippe

    2015-01-01

    The aim of this study is to apply the membrane bioreactor technology in an oxidation ditch in submerged conditions. This new wastewater filtration process will benefit rural areas (membranes developed without support are immersed in an aeration well and work in suction mode. The development of the membrane without support and more precisely the performance of spacers are approached by computational fluid dynamics in order to provide the best compromise between pressure drop/flow velocity and permeate flux. The numerical results on the layout and the membrane modules' geometry in the aeration well indicate that the optimal configuration is to install the membranes horizontally on three levels. Membranes should be connected to each other to a manifold providing a total membrane area of 18 m². Loss rate compared to the theoretical throughput is relatively low (less than 3%). Preliminary data obtained by modeling the lagoon provide access to its hydrodynamics, revealing that recirculation zones can be optimized by making changes in the operating conditions. The experimental validation of these results and taking into account the aeration in the numerical models are underway.

  9. The Balance of Fluid and Osmotic Pressures across Active Biological Membranes with Application to the Corneal Endothelium.

    Directory of Open Access Journals (Sweden)

    Xi Cheng

    Full Text Available The movement of fluid and solutes across biological membranes facilitates the transport of nutrients for living organisms and maintains the fluid and osmotic pressures in biological systems. Understanding the pressure balances across membranes is crucial for studying fluid and electrolyte homeostasis in living systems, and is an area of active research. In this study, a set of enhanced Kedem-Katchalsky (KK equations is proposed to describe fluxes of water and solutes across biological membranes, and is applied to analyze the relationship between fluid and osmotic pressures, accounting for active transport mechanisms that propel substances against their concentration gradients and for fixed charges that alter ionic distributions in separated environments. The equilibrium analysis demonstrates that the proposed theory recovers the Donnan osmotic pressure and can predict the correct fluid pressure difference across membranes, a result which cannot be achieved by existing KK theories due to the neglect of fixed charges. The steady-state analysis on active membranes suggests a new pressure mechanism which balances the fluid pressure together with the osmotic pressure. The source of this pressure arises from active ionic fluxes and from interactions between solvent and solutes in membrane transport. We apply the proposed theory to study the transendothelial fluid pressure in the in vivo cornea, which is a crucial factor maintaining the hydration and transparency of the tissue. The results show the importance of the proposed pressure mechanism in mediating stromal fluid pressure and provide a new interpretation of the pressure modulation mechanism in the in vivo cornea.

  10. Polyhydroxyalkanoate (PHA) Granules Have no Phospholipids

    Science.gov (United States)

    Bresan, Stephanie; Sznajder, Anna; Hauf, Waldemar; Forchhammer, Karl; Pfeiffer, Daniel; Jendrossek, Dieter

    2016-01-01

    Polyhydroxybutyrate (PHB) granules, also designated as carbonosomes, are supra-molecular complexes in prokaryotes consisting of a PHB polymer core and a surface layer of structural and functional proteins. The presence of suspected phospholipids in the surface layer is based on in vitro data of isolated PHB granules and is often shown in cartoons of the PHB granule structure in reviews on PHB metabolism. However, the in vivo presence of a phospholipid layer has never been demonstrated. We addressed this topic by the expression of fusion proteins of DsRed2EC and other fluorescent proteins with the phospholipid-binding domain (LactC2) of lactadherin in three model organisms. The fusion proteins specifically localized at the cell membrane of Ralstonia eutropha but did not co-localize with PHB granules. The same result was obtained for Pseudomonas putida, a species that accumulates another type of polyhydroxyalkanoate (PHA) granules related to PHB. Notably, DsRed2EC-LactC2 expressed in Magnetospirillum gryphiswaldense was detected at the position of membrane-enclosed magnetosome chains and at the cytoplasmic membrane but not at PHB granules. In conclusion, the carbonosomes of representatives of α-proteobacteria, β-proteobacteria and γ-proteobacteria have no phospholipids in vivo and we postulate that the PHB/PHA granule surface layers in natural producers generally are free of phospholipids and consist of proteins only. PMID:27222167

  11. Membranes having aligned 1-D nanoparticles in a matrix layer for improved fluid separation

    Science.gov (United States)

    Revanur, Ravindra; Lulevich, Valentin; Roh, Il Juhn; Klare, Jennifer E.; Kim, Sangil; Noy, Aleksandr; Bakajin, Olgica

    2015-12-22

    Membranes for fluid separation are disclosed. These membranes have a matrix layer sandwiched between an active layer and a porous support layer. The matrix layer includes 1-D nanoparticles that are vertically aligned in a porous polymer matrix, and which substantially extend through the matrix layer. The active layer provides species-specific transport, while the support layer provides mechanical support. A matrix layer of this type has favorable surface morphology for forming the active layer. Furthermore, the pores that form in the matrix layer tend to be smaller and more evenly distributed as a result of the presence of aligned 1-D nanoparticles. Improved performance of separation membranes of this type is attributed to these effects.

  12. The diagnostic value of the lactate concentration in the vaginal fluid for diagnosis of premature rupture of membranes

    Directory of Open Access Journals (Sweden)

    N Nazari

    2013-11-01

    Conclusion: Test of Lactate concentration in vaginal fluid test is a valid, quick and easy with high sensitivity and specificity for the diagnosis of premature rupture of membranes the fetus of pregnant women.

  13. Morphological and physical analysis of natural phospholipids-based biomembranes.

    Directory of Open Access Journals (Sweden)

    Adrien Jacquot

    Full Text Available BACKGROUND: Liposomes are currently an important part of biological, pharmaceutical, medical and nutritional research, as they are considered to be among the most effective carriers for the introduction of various types of bioactive agents into target cells. SCOPE OF REVIEW: In this work, we study the lipid organization and mechanical properties of biomembranes made of marine and plant phospholipids. Membranes based on phospholipids extracted from rapeseed and salmon are studied in the form of liposome and as supported lipid bilayer. Dioleylphosphatidylcholine (DOPC and dipalmitoylphosphatidylcholine (DPPC are used as references to determine the lipid organization of marine and plant phospholipid based membranes. Atomic force microscopy (AFM imaging and force spectroscopy measurements are performed to investigate the membranes' topography at the micrometer scale and to determine their mechanical properties. MAJOR CONCLUSIONS: The mechanical properties of the membranes are correlated to the fatty acid composition, the morphology, the electrophoretic mobility and the membrane fluidity. Thus, soft and homogeneous mechanical properties are evidenced for salmon phospholipids membrane containing various polyunsaturated fatty acids. Besides, phase segregation in rapeseed membrane and more important mechanical properties were emphasized for this type of membranes by contrast to the marine phospholipids based membranes. GENERAL SIGNIFICANCE: This paper provides new information on the nanomechanical and morphological properties of membrane in form of liposome by AFM. The originality of this work is to characterize the physico-chemical properties of the nanoliposome from the natural sources containing various fatty acids and polar head.

  14. Deformation of phospholipid vesicles in an optical stretcher

    OpenAIRE

    Delabre , Ulysse; Feld , Kasper; Crespo , Eleonore; Whyte , Graeme; Sykes , Cecile; Seifert , Udo; Guck , Jochen

    2015-01-01

    International audience; Phospholipid vesicles are common model systems for cell membranes. Important aspects of the membrane function relate to its mechanical properties. Here we have investigated the deformation behaviour of phospholipid vesicles in a dual-beam laser trap, also called an optical stretcher. This study explicitly makes use of the inherent heating present in such traps to investigate the dependence of vesicle deformation on temperature. By using lasers with different wavelength...

  15. Chemistry of phospholipid oxidation.

    Science.gov (United States)

    Reis, Ana; Spickett, Corinne M

    2012-10-01

    The oxidation of lipids has long been a topic of interest in biological and food sciences, and the fundamental principles of non-enzymatic free radical attack on phospholipids are well established, although questions about detail of the mechanisms remain. The number of end products that are formed following the initiation of phospholipid peroxidation is large, and is continually growing as new structures of oxidized phospholipids are elucidated. Common products are phospholipids with esterified isoprostane-like structures and chain-shortened products containing hydroxy, carbonyl or carboxylic acid groups; the carbonyl-containing compounds are reactive and readily form adducts with proteins and other biomolecules. Phospholipids can also be attacked by reactive nitrogen and chlorine species, further expanding the range of products to nitrated and chlorinated phospholipids. Key to understanding the mechanisms of oxidation is the development of advanced and sensitive technologies that enable structural elucidation. Tandem mass spectrometry has proved invaluable in this respect and is generally the method of choice for structural work. A number of studies have investigated whether individual oxidized phospholipid products occur in vivo, and mass spectrometry techniques have been instrumental in detecting a variety of oxidation products in biological samples such as atherosclerotic plaque material, brain tissue, intestinal tissue and plasma, although relatively few have achieved an absolute quantitative analysis. The levels of oxidized phospholipids in vivo is a critical question, as there is now substantial evidence that many of these compounds are bioactive and could contribute to pathology. The challenges for the future will be to adopt lipidomic approaches to map the profile of oxidized phospholipid formation in different biological conditions, and relate this to their effects in vivo. This article is part of a Special Issue entitled: Oxidized phospholipids

  16. A Fluid Membrane-Based Soluble Ligand Display System for Live CellAssays

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Jwa-Min; Nair, Pradeep N.; Neve, Richard M.; Gray, Joe W.; Groves, Jay T.

    2005-10-14

    Cell communication modulates numerous biological processes including proliferation, apoptosis, motility, invasion and differentiation. Correspondingly, there has been significant interest in the development of surface display strategies for the presentation of signaling molecules to living cells. This effort has primarily focused on naturally surface-bound ligands, such as extracellular matrix components and cell membranes. Soluble ligands (e.g. growth factors and cytokines) play an important role in intercellular communications, and their display in a surface-bound format would be of great utility in the design of array-based live cell assays. Recently, several cell microarray systems that display cDNA, RNAi, or small molecules in a surface array format were proven to be useful in accelerating high-throughput functional genetic studies and screening therapeutic agents. These surface display methods provide a flexible platform for the systematic, combinatorial investigation of genes and small molecules affecting cellular processes and phenotypes of interest. In an analogous sense, it would be an important advance if one could display soluble signaling ligands in a surface assay format that allows for systematic, patterned presentation of soluble ligands to live cells. Such a technique would make it possible to examine cellular phenotypes of interest in a parallel format with soluble signaling ligands as one of the display parameters. Herein we report a ligand-modified fluid supported lipid bilayer (SLB) assay system that can be used to functionally display soluble ligands to cells in situ (Figure 1A). By displaying soluble ligands on a SLB surface, both solution behavior (the ability to become locally enriched by reaction-diffusion processes) and solid behavior (the ability to control the spatial location of the ligands in an open system) could be combined. The method reported herein benefits from the naturally fluid state of the supported membrane, which allows

  17. Phospholipid composition of cell-derived microparticles determined by one-dimensional high-performance thin-layer chromatography

    NARCIS (Netherlands)

    Weerheim, A. M.; Kolb, A. M.; Sturk, A.; Nieuwland, R.

    2002-01-01

    Microparticles in the circulation activate the coagulation system and may activate the complement system via C-reactive protein upon conversion of membrane phospholipids by phospholipases. We developed a sensitive and reproducible method to determine the phospholipid composition of microparticles.

  18. Hamilton's equations for a fluid membrane: axial symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Capovilla, R [Departamento de Fisica, Centro de Investigacion y de Estudios Avanzados del IPN, Apdo Postal 14-740, 07000 Mexico, DF (Mexico); Guven, J [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Apdo Postal 70-543, 04510 Mexico, DF (Mexico); Rojas, E [Facultad de Fisica e Inteligencia Artificial, Universidad Veracruzana, 91000 Xalapa, Veracruz (Mexico)

    2005-09-23

    Consider a homogeneous fluid membrane, or vesicle, described by the Helfrich-Canham energy, quadratic in the mean curvature. When the membrane is axially symmetric, this energy can be viewed as an 'action' describing the motion of a particle; the contours of equilibrium geometries are identified with particle trajectories. A novel Hamiltonian formulation of the problem is presented which exhibits the following two features: (i) the second derivatives appearing in the action through the mean curvature are accommodated in a natural phase space and (ii) the intrinsic freedom associated with the choice of evolution parameter along the contour is preserved. As a result, the phase space involves momenta conjugate not only to the particle position but also to its velocity, and there are constraints on the phase space variables. This formulation provides the groundwork for a field theoretical generalization to arbitrary configurations, with the particle replaced by a loop in space.

  19. Hybrid, Nanoscale Phospholipid/Block Copolymer Vesicles

    Directory of Open Access Journals (Sweden)

    Bo Liedberg

    2013-09-01

    Full Text Available Hybrid phospholipid/block copolymer vesicles, in which the polymeric membrane is blended with phospholipids, display interesting self-assembly behavior, incorporating the robustness and chemical versatility of polymersomes with the softness and biocompatibility of liposomes. Such structures can be conveniently characterized by preparing giant unilamellar vesicles (GUVs via electroformation. Here, we are interested in exploring the self-assembly and properties of the analogous nanoscale hybrid vesicles (ca. 100 nm in diameter of the same composition prepared by film-hydration and extrusion. We show that the self-assembly and content-release behavior of nanoscale polybutadiene-b-poly(ethylene oxide (PB-PEO/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC hybrid phospholipid/block copolymer vesicles can be tuned by the mixing ratio of the amphiphiles. In brief, these hybrids may provide alternative tools for drug delivery purposes and molecular imaging/sensing applications and clearly open up new avenues for further investigation.

  20. Applications of Amniotic Membrane and Fluid in Stem Cell Biology and Regenerative Medicine

    Directory of Open Access Journals (Sweden)

    Kerry Rennie

    2012-01-01

    Full Text Available The amniotic membrane (AM and amniotic fluid (AF have a long history of use in surgical and prenatal diagnostic applications, respectively. In addition, the discovery of cell populations in AM and AF which are widely accessible, nontumorigenic and capable of differentiating into a variety of cell types has stimulated a flurry of research aimed at characterizing the cells and evaluating their potential utility in regenerative medicine. While a major focus of research has been the use of amniotic membrane and fluid in tissue engineering and cell replacement, AM- and AF-derived cells may also have capabilities in protecting and stimulating the repair of injured tissues via paracrine actions, and acting as vectors for biodelivery of exogenous factors to treat injury and diseases. Much progress has been made since the discovery of AM and AF cells with stem cell characteristics nearly a decade ago, but there remain a number of problematic issues stemming from the inherent heterogeneity of these cells as well as inconsistencies in isolation and culturing methods which must be addressed to advance the field towards the development of cell-based therapies. Here, we provide an overview of the recent progress and future perspectives in the use of AM- and AF-derived cells for therapeutic applications.

  1. RED WINE EXTRACT OBTAINED BY MEMBRANE-BASED SUPERCRITICAL FLUID EXTRACTION: PRELIMINARY CHARACTERIZATION OF CHEMICAL PROPERTIES.

    Directory of Open Access Journals (Sweden)

    W. Silva

    Full Text Available ABSTRACT This study aims to obtain an extract from red wine by using membrane-based supercritical fluid extraction. This technique involves the use of porous membranes as contactors during the dense gas extraction process from liquid matrices. In this work, a Cabernet Sauvignon wine extract was obtained from supercritical fluid extraction using pressurized carbon dioxide as solvent and a hollow fiber contactor as extraction setup. The process was continuously conducted at pressures between 12 and 18 MPa and temperatures ranged from 30 to 50ºC. Meanwhile, flow rates of feed wine and supercritical CO2 varied from 0.1 to 0.5 mL min-1 and from 60 to 80 mL min-1 (NCPT, respectively. From extraction assays, the highest extraction percentage value obtained from the total amount of phenolic compounds was 14% in only one extraction step at 18MPa and 35ºC. A summarized chemical characterization of the obtained extract is reported in this work; one of the main compounds in this extract could be a low molecular weight organic acid with aromatic structure and methyl and carboxyl groups. Finally, this preliminary characterization of this extract shows a remarkable ORAC value equal to 101737 ± 5324 µmol Trolox equivalents (TE per 100 g of extract.

  2. Comparison of Four Types of Membrane Bioreactor Systems in Terms of Shear Stress over the Membrane Surface using Computational Fluid Dynamics

    DEFF Research Database (Denmark)

    Ratkovich, Nicolas Rios; Bentzen, Thomas Ruby

    2013-01-01

    Membrane bioreactors (MBRs) have been used successfully in biological wastewater treatment to solve the perennial problem of effective solids–liquid separation. A common problem with MBR systems is clogging of the modules and fouling of the membrane, resulting in frequent cleaning and replacement...... and requires knowledge of the membrane fouling, hydrodynamics and biokinetics. Modern tools such as computational fluid dynamics (CFD) can be used to diagnose and understand the two-phase flow in an MBR. Four cases of different MBR configurations are presented in this work, using CFD as a tool to develop...

  3. Near field fluid coupling between internal motion of the organ of Corti and the basilar membrane

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, Stephen J.; Ni, Guangjian [Institute of Sound and Vibration Research, University of Southampton, Southampton (United Kingdom)

    2015-12-31

    The pressure distribution in each of the fluid chambers of the cochlea can be decomposed into a 1D, or plane wave, component and a near field component, which decays rapidly away from the excitation point. The transverse motion of the basilar membrane, BM, for example, generates both a 1D pressure field, which couples into the slow wave, and a local near field pressure, proportional to the BM acceleration, that generates an added mass on the BM due to the fluid motion. When the organ of Corti, OC, undergoes internal motion, due for example to outer hair cell activity, this motion will not itself generate any 1D pressure if the OC is incompressible and the BM is constrained not to move volumetrically, and so will not directly couple into the slow wave. This motion will, however, generate a near field pressure, proportional to the OC acceleration, which will act on the OC and thus increases its effective mass. The near field pressure due to this OC motion will also act on the BM, generating a force on the BM proportional to the acceleration of the OC, and thus create a “coupling mass” effect. By reciprocity, this coupling mass is the same as that acting on the OC due to the motion of the BM. This near field fluid coupling is initially observed in a finite element model of a slice of the cochlea. These simulations suggest a simple analytical formulation for the fluid coupling, using higher order beam modes across the width of the cochlear partition. It is well known that the added mass due to the near field pressure dominates the overall mass of the BM, and thus significantly affects the micromechanical dynamics. This work not only quantifies the added mass of the OC due its own motion in the fluid, and shows that this is important, but also demonstrates that the coupling mass effect between the BM and OC significantly affects the dynamics of simple micromechanical models.

  4. Autistic disorder and phospholipids: A review.

    Science.gov (United States)

    Brown, Christine M; Austin, David W

    2011-01-01

    Dysregulated phospholipid metabolism has been proposed as an underlying biological component of neurodevelopmental disorders such as autistic disorder (AD) and attention-deficit/hyperactivity disorder (ADHD). This review provides an overview of fatty acid and phospholipid metabolism and evidence for phospholipid dysregulation with reference to the membrane hypothesis of schizophrenia. While there is evidence that phospholipid metabolism is at least impaired in individuals with AD, it has not been established whether phospholipid metabolism is implicated in causal, mechanistic or epiphenomenological models. More research is needed to ascertain whether breastfeeding, and specifically, the administration of colostrum or an adequate substitute can play a preventative role by supplying the neonate with essential fatty acids (EFAs) at a critical juncture in their development. Regarding treatment, further clinical trials of EFA supplementation are essential to determine the efficacy of EFAs in reducing AD symptomatology and whether supplementation can serve as a cost-effective and readily available intervention. Crown Copyright © 2010. Published by Elsevier Ltd. All rights reserved.

  5. Potential antitumor therapeutic strategies of human amniotic membrane and amniotic fluid-derived stem cells.

    Science.gov (United States)

    Kang, N-H; Hwang, K-A; Kim, S U; Kim, Y-B; Hyun, S-H; Jeung, E-B; Choi, K-C

    2012-08-01

    As stem cells are capable of self-renewal and can generate differentiated progenies for organ development, they are considered as potential source for regenerative medicine and tissue replacement after injury or disease. Along with this capacity, stem cells have the therapeutic potential for treating human diseases including cancers. According to the origins, stem cells are broadly classified into two types: embryonic stem cells (ESCs) and adult stem cells. In terms of differentiation potential, ESCs are pluripotent and adult stem cells are multipotent. Amnion, which is a membranous sac that contains the fetus and amniotic fluid and functions in protecting the developing embryo during gestation, is another stem cell source. Amnion-derived stem cells are classified as human amniotic membrane-derived epithelial stem cells, human amniotic membrane-derived mesenchymal stem cells and human amniotic fluid-derived stem cells. They are in an intermediate stage between pluripotent ESCs and lineage-restricted adult stem cells, non-tumorigenic, and contribute to low immunogenicity and anti-inflammation. Furthermore, they are easily available and do not cause any controversial issues in their recovery and applications. Not only are amnion-derived stem cells applicable in regenerative medicine, they have anticancer capacity. In non-engineered stem cells transplantation strategies, amnion-derived stem cells effectively target the tumor and suppressed the tumor growth by expressing cytotoxic cytokines. Additionally, they also have a potential as novel delivery vehicles transferring therapeutic genes to the cancer formation sites in gene-directed enzyme/prodrug combination therapy. Owing to their own advantageous properties, amnion-derived stem cells are emerging as a new candidate in anticancer therapy.

  6. Fabrication of an Anti-Biofouling Plasma-Filtration Membrane by an Electrospinning Process Using Photo-Cross-linkable Zwitterionic Phospholipid Polymers.

    Science.gov (United States)

    Seo, Jiae; Seo, Ji-Hun

    2017-06-14

    The goal of this study is to fabricate a stable plasma filtration membrane with antibiofouling properties via an electrospinning process. To this end, a random-type copolymer consisting of zwitterionic phosphorylcholine (PC) groups and ultraviolet (UV)-cross-linkable phenyl azide groups was synthesized. The zwitterionic PC group provides antibiofouling properties, and the phenyl azide group enables the stable maintenance of the fibrous nanostructure of hydrophilic zwitterion polymers in aqueous medium via a simple UV curing process. To demonstrate the antibiofouling nature of the PC group, a polymer without antibiofouling PC groups was also prepared for comparison. The successful synthesis of the random-type copolymers containing phenyl azide groups was proven by 1 H nuclear magnetic resonance and Fourier transform infrared spectroscopy, and the fibrous structure of the prepared membranes was observed by field emission scanning electron microscopy. The antibiofouling properties were analyzed by fluorescein isothiocyanate-labeled bovine serum albumin adsorption and platelet adhesion tests. The experimental results show that membranes containing zwitterionic PC groups exhibited obvious decreases in platelet adhesion and protein adsorption. Platelet-rich plasma solution was filtered using the prepared membranes to test their filtration properties. The sequential filtration process removed 80% and almost 98% of the platelets. This finding confirmed that the membrane retained its blood-inert biomaterial surface in a complex medium that included blood plasma and platelets.

  7. Amnioinfusion in term labor with low amniotic fluid due to rupture of membranes: a new indication.

    Science.gov (United States)

    Miño, M; Puertas, A; Miranda, J A; Herruzo, A J

    1999-01-01

    The null hypothesis was that the use of intrapartum amnioinfusion to induce term labor because of premature rupture of membranes when labor was complicated by low amniotic fluid volume due to vaginal loss would not improve fetal heart rate patterns, decrease the incidence of operative delivery, or improve neonatal acid-base status. 200 term pregnancies with low amniotic fluid due to vaginal loss were randomly chosen to receive intrapartum amnioinfusion or standard obstetric care without amnioinfusion. Fetal heart rate pattern, method of delivery and neonatal acid-base status were compared with Student's t test, chi-squared analysis, Mann-Whitney U- or Fisher's exact test. When amnioinfusion was used, the fetuses had lower rates of variable (74 vs. 91%, Pamnioinfusion, and babies in this group had lower rates of neonatal acidemia of arterial (22 vs. 36%, PAmnioinfusion improved fetal heart rate pattern, lowered the incidence of operative delivery, and improved neonatal acid-base status in term labor complicated by low amniotic fluid due to vaginal loss.

  8. Synthesis and membrane behavior of a new class of unnatural phospholipid analogs useful as phospholipase A2 degradable liposomal drug carriers

    DEFF Research Database (Denmark)

    Andresen, Thomas Lars; Jørgensen, Kent

    2005-01-01

    A new and unnatural type of lipid analogs with the phosphocholine and phosphoglycerol head groups linked to the C-2 position of the glycerol moiety have been synthesized and the thermodynamic lipid membrane behavior has been investigated using differential scanning calorimetry. From the heat capa...

  9. Electrostatic control of phospholipid polymorphism.

    Science.gov (United States)

    Tarahovsky, Y S; Arsenault, A L; MacDonald, R C; McIntosh, T J; Epand, R M

    2000-12-01

    A regular progression of polymorphic phase behavior was observed for mixtures of the anionic phospholipid, cardiolipin, and the cationic phospholipid derivative, 1, 2-dioleoyl-sn-glycero-3-ethylphosphocholine. As revealed by freeze-fracture electron microscopy and small-angle x-ray diffraction, whereas the two lipids separately assume only lamellar phases, their mixtures exhibit a symmetrical (depending on charge ratio and not polarity) sequence of nonlamellar phases. The inverted hexagonal phase, H(II,) formed from equimolar mixtures of the two lipids, i.e., at net charge neutrality (charge ratio (CR((+/-))) = 1:1). When one type of lipid was in significant excess (CR((+/-)) = 2:1 or CR((+/-)) = 1:2), a bicontinuous cubic structure was observed. These cubic phases were very similar to those sometimes present in cellular organelles that contain cardiolipin. Increasing the excess of cationic or anionic charge to CR((+/-)) = 4:1 or CR((+/-)) = 1:4 led to the appearance of membrane bilayers with numerous interlamellar contacts, i.e., sponge structures. It is evident that interactions between cationic and anionic moieties can influence the packing of polar heads and hence control polymorphic phase transitions. The facile isothermal, polymorphic interconversion of these lipids may have important biological and technical implications.

  10. The diagnostic value of the lactate level in the vaginal fluid for determining the premature rupture of membranes

    International Nuclear Information System (INIS)

    Ahmadi, M.; Rafaei, F.; Nazari, N.

    2013-01-01

    Objectives:To determine the diagnostic value of the lactate concentration in vaginal secretions in determining the premature rupture of membranes. Subjects and Methods:One hundred 100 pregnant women with single pregnancy of gestational age 20--41 weeks were divided to two groups of 50 each. One group comprised of women with premature rupture of membranes, and the other (control group) of women with intact membranes. To verify the premature rupture of membranes in both groups, the speculum, fern, and nitrazine tests were done. Lactate Pro manual instrument was used to measure the lactate levels in vaginal fluid via enzymatic staining which was displayed on the instrument's liquid crystal display after 60 seconds. Descriptive analytic statistics and SPSS 17 software were used to analyze the data. Results The lactate concentration of 4.6 mM in the vaginal fluid was diagnostic for premature rupture of membranes. It had a sensitivity of 96%, specificity of 98.8%, accuracy of 97%, positive predictive value of 97.9%, and negative predictive value of 96%. Conclusions:Testing lactate levels in the vaginal fluid is an easy, rapid and reliable method for the diagnosis of premature rupture of membranes in pregnancy. (author)

  11. Liposome Model Systems to Study the Endosomal Escape of Cell-Penetrating Peptides: Transport across Phospholipid Membranes Induced by a Proton Gradient

    Directory of Open Access Journals (Sweden)

    Fatemeh Madani

    2011-01-01

    Full Text Available Detergent-mediated reconstitution of bacteriorhodopsin (BR into large unilamellar vesicles (LUVs was investigated, and the effects were carefully characterized for every step of the procedure. LUVs were prepared by the extrusion method, and their size and stability were examined by dynamic light scattering. BR was incorporated into the LUVs using the detergent-mediated reconstitution method and octyl glucoside (OG as detergent. The result of measuring pH outside the LUVs suggested that in the presence of light, BR pumps protons from the outside to the inside of the LUVs, creating acidic pH inside the vesicles. LUVs with 20% negatively charged headgroups were used to model endosomes with BR incorporated into the membrane. The fluorescein-labeled cell-penetrating peptide penetratin was entrapped inside these BR-containing LUVs. The light-induced proton pumping activity of BR has allowed us to observe the translocation of fluorescein-labeled penetratin across the vesicle membrane.

  12. Progesterone modulation of transmembrane helix-helix interactions between the α-subunit of Na/K-ATPase and phospholipid N-methyltransferase in the oocyte plasma membrane

    Directory of Open Access Journals (Sweden)

    Askari Amir

    2010-05-01

    Full Text Available Abstract Background Progesterone binding to the surface of the amphibian oocyte initiates the meiotic divisions. Our previous studies with Rana pipiens oocytes indicate that progesterone binds to a plasma membrane site within the external loop between the M1 and M2 helices of the α-subunit of Na/K-ATPase, triggering a cascade of lipid second messengers and the release of the block at meiotic prophase. We have characterized this site, using a low affinity ouabain binding isoform of the α1-subunit. Results Preparations of isolated plasma membranes from Rana oocytes demonstrate that physiological levels of progesterone (or the non-metabolizable progestin R5020 successively activate phosphatidylethanolamine-N-methyltransferase (PE-NMT and sphingomyelin synthase within seconds. Inhibition of PE-NMT blocks the progesterone induction of meiosis in intact oocytes, whereas its initial product, phosphatidylmonomethylethanolamine (PME, can itself initiate meiosis in the presence of the inhibitor. Published X-ray crystallographic data on Na/K-ATPase, computer-generated 3D projections, heptad repeat analysis and hydrophobic cluster analysis of the transmembrane helices predict that hydrophobic residues L, V, V, I, F and Y of helix M2 of the α1-subunit interact with F, L, G, L, L and F, respectively, of helix M3 of PE-NMT. Conclusion We propose that progesterone binding to the first external loop of the α1-subunit facilitates specific helix-helix interactions between integral membrane proteins to up-regulate PE-NMT, and, that successive interactions between two or more integral plasma membrane proteins induce the signaling cascades which result in completion of the meiotic divisions.

  13. Purification and characterization of lutropin receptor from membranes of pig follicular fluid

    Energy Technology Data Exchange (ETDEWEB)

    Yarney, T.A.; Sairam, M.R.; Bhargavi, G.N.; Mohapatra, S.K. (Clinical Research Institute of Montreal, Quebec (Canada))

    1990-04-10

    Membranes derived from free floating granulosa cells in porcine ovarian follicular fluid were used as a starting material for structural characterization of both LH/hCG and FSH receptors. The receptors were highly hormone-specific and showed single classes of high-affinity binding sites. Their molecular weights as determined by affinity cross-linking with their respective {sup 125}I-ligands were similarly 70,000. The membrane-localized receptors could be solubilized with reduced Triton X-100 in the presence of 20% glycerol with good retention of hormone binding activity. The purified receptor exhibited a high specificity for hCG and hLH but not for hFSH bTSH. The purified receptor was iodinated and visualized to be composed of a major protein of M{sub r} 70,000 and other minor proteins of molecular weights ranging from 14,000 to 40,000. Except for the M{sub r} 14,000 protein, all other protein species bound to the concanavalin A-Sepharose column. The data suggest that the ovarian LH/hCG and FSH receptors are structurally similar and consist of a single polypeptide chain, as recently documented for the LH/hCG receptor.

  14. New generation of membrane efficient water-based drilling fluids: pragmatic and cost-effective solutions to borehole stability problems

    Energy Technology Data Exchange (ETDEWEB)

    Tare, U.A. [Haliburton, Calgary, AB (Canada); Mody, F.K. [Shell International E and P Inc., Calgary, AB (Canada); Tan, C.P. [CSIRO Petroleum, Kensington, WA (Australia)

    2002-06-01

    Drilling and completion operations in shales often suffer as a result of wellbore instability. Mechanical failure of the rock around a wellbore is the primary cause of shale instability. This process can be exacerbated by physico-chemical interactions between drilling fluids and shales. Water-based drilling fluids are used more and more due to environmental awareness that becomes more prevalent. Wellbore instability problems can however result from an improper application of water-based drilling fluids in those cases where drilling occurs in sensitive clay-rich formations. To meet the requirements of the petroleum industry, considerable collaborative efforts were expanded in the development of innovative environmentally acceptable water-based drilling fluids. In this paper, the authors describe the process that leads to the development of these drilling fluids. It is possible to achieve shale stability through an osmotic outflow of pore fluid and prevention/minimization of mud pressure penetration, as laboratory experiments on shale samples under realistic downhole conditions exposed to these drilling fluids prove. High membrane efficiencies, in excess of 80 per cent, were generated by this new generation of membrane efficient water-based drilling fluids. Drilling objectives resulting from an improved application of water-based drilling fluids are made possible by a fundamental understanding of the main drilling fluid-shale interaction mechanisms for shale stability and the application of experimental data to field conditions. The authors indicate that the achievement of trouble-free drilling of shales and notable reductions in non-productive time is accomplished by following the practical guidelines included in this paper for maintaining shale stability with the new generation of water-based drilling fluids. 8 refs., 2 tabs., 4 figs.

  15. Biosynthesis of ether-phospholipids including plasmalogens, peroxisomes and human disease: new insights into an old problem

    NARCIS (Netherlands)

    Wanders, Ronald J. A.; Brites, Pedro

    2010-01-01

    Ether-phospholipids represent an important subclass of phospholipids in animal cell membranes characterized by the presence of an ether bond at the sn-I position and the enrichment of PUFAs at the sn-2 position. Of the different ether-phospholipids, plasmalogens are the most abundant form and their

  16. Morphological and Physical Analysis of Natural Phospholipids-Based Biomembranes

    OpenAIRE

    Jacquot, Adrien; Francius, Grégory; Razafitianamaharavo, Angelina; Dehghani, Fariba; Tamayol, Ali; Linder, Michel; Arab-Tehrany, Elmira

    2014-01-01

    International audience; Background: Liposomes are currently an important part of biological, pharmaceutical, medical and nutritional research, as they are considered to be among the most effective carriers for the introduction of various types of bioactive agents into target cells.Scope of Review: In this work, we study the lipid organization and mechanical properties of biomembranes made of marine and plant phospholipids. Membranes based on phospholipids extracted from rapeseed and salmon ar...

  17. The anti-apoptotic effect of fluid mechanics preconditioning by cells membrane and mitochondria in rats brain microvascular endothelial cells.

    Science.gov (United States)

    Tian, Shan; Zhu, Fengping; Hu, Ruiping; Tian, Song; Chen, Xingxing; Lou, Dan; Cao, Bing; Chen, Qiulei; Li, Bai; Li, Fang; Bai, Yulong; Wu, Yi; Zhu, Yulian

    2018-01-01

    Exercise preconditioning is a simple and effective way to prevent ischemia. This paper further provided the mechanism in hemodynamic aspects at the cellular level. To study the anti-apoptotic effects of fluid mechanics preconditioning, Cultured rats brain microvascular endothelial cells were given fluid intervention in a parallel plate flow chamber before oxygen glucose deprivation. It showed that fluid mechanics preconditioning could inhibit the apoptosis of endothelial cells, and this process might be mediated by the shear stress activation of Tie-2 on cells membrane surface and Bcl-2 on the mitochondria surface. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Annexin-Phospholipid Interactions. Functional Implications

    Directory of Open Access Journals (Sweden)

    Javier Turnay

    2013-01-01

    Full Text Available Annexins constitute an evolutionary conserved multigene protein superfamily characterized by their ability to interact with biological membranes in a calcium dependent manner. They are expressed by all living organisms with the exception of certain unicellular organisms. The vertebrate annexin core is composed of four (eight in annexin A6 homologous domains of around 70 amino acids, with the overall shape of a slightly bent ring surrounding a central hydrophilic pore. Calcium- and phospholipid-binding sites are located on the convex side while the N-terminus links domains I and IV on the concave side. The N-terminus region shows great variability in length and amino acid sequence and it greatly influences protein stability and specific functions of annexins. These proteins interact mainly with acidic phospholipids, such as phosphatidylserine, but differences are found regarding their affinity for lipids and calcium requirements for the interaction. Annexins are involved in a wide range of intra- and extracellular biological processes in vitro, most of them directly related with the conserved ability to bind to phospholipid bilayers: membrane trafficking, membrane-cytoskeleton anchorage, ion channel activity and regulation, as well as antiinflammatory and anticoagulant activities. However, the in vivo physiological functions of annexins are just beginning to be established.

  19. Control of phospholipid flip-flop by transmembrane peptides

    International Nuclear Information System (INIS)

    Kaihara, Masanori; Nakao, Hiroyuki; Yokoyama, Hirokazu; Endo, Hitoshi; Ishihama, Yasushi; Handa, Tetsurou; Nakano, Minoru

    2013-01-01

    Highlights: ► Phospholipid flip-flop in transmembrane peptide-containing vesicles was investigated. ► Peptides that contained polar residues in the center of the transmembrane region promoted phospholipid flip-flop. ► A bioinformatics approach revealed the presence of polar residues in the transmembrane region of ER membrane proteins. ► Polar residues in ER membrane proteins possibly provide flippase-like activity. - Abstract: We designed three types of transmembrane model peptides whose sequence originates from a frequently used model peptide KALP23, and we investigated their effects on phospholipid flip-flop. Time-resolved small-angle neutron scattering and a dithionite fluorescent quenching assay demonstrated that TMP-L, which has a fully hydrophobic transmembrane region, did not enhance phospholipid flip-flop, whereas TMP-K and TMP-E, which have Lys and Glu, respectively, in the center of their transmembrane regions, enhanced phospholipid flip-flop. Introduction of polar residues in the membrane-spanning helices is considered to produce a locally polar region and enable the lipid head group to interact with the polar side-chain inside the bilayers, thereby reducing the activation energy for the flip-flop. A bioinformatics approach revealed that acidic and basic residues account for 4.5% of the central region of the transmembrane domain in human ER membrane proteins. Therefore, polar residues in ER membrane proteins are considered to provide flippase-like activity

  20. Phospholipid composition of Dipylidium caninum.

    Science.gov (United States)

    Chopra, A K; Jain, S K; Vinayak, V K; Khuller, G K

    1978-11-15

    The phospholipid composition of Dipylidium caninum has been studied. Chloroform-methanol-soluble fraction amounted to 2.4% and phospholipids to 0.5% of the wet weight of the parasite. Phosphatidyl choline and phosphatidyl ethanolamine represented the bulk of the phospholipids, whereas phosphatidyl serine, phosphatidyl inositol, lysolecithin and lysophosphatidyl ethanolamine were present in minor amounts. Sulfatides were also identified in this parasite.

  1. Confocal Raman Microscopy for in Situ Measurement of Phospholipid-Water Partitioning into Model Phospholipid Bilayers within Individual Chromatographic Particles.

    Science.gov (United States)

    Kitt, Jay P; Bryce, David A; Minteer, Shelley D; Harris, Joel M

    2018-06-05

    The phospholipid-water partition coefficient is a commonly measured parameter that correlates with drug efficacy, small-molecule toxicity, and accumulation of molecules in biological systems in the environment. Despite the utility of this parameter, methods for measuring phospholipid-water partition coefficients are limited. This is due to the difficulty of making quantitative measurements in vesicle membranes or supported phospholipid bilayers, both of which are small-volume phases that challenge the sensitivity of many analytical techniques. In this work, we employ in situ confocal Raman microscopy to probe the partitioning of a model membrane-active compound, 2-(4-isobutylphenyl) propionic acid or ibuprofen, into both hybrid- and supported-phospholipid bilayers deposited on the pore walls of individual chromatographic particles. The large surface-area-to-volume ratio of chromatographic silica allows interrogation of a significant lipid bilayer area within a very small volume. The local phospholipid concentration within a confocal probe volume inside the particle can be as high as 0.5 M, which overcomes the sensitivity limitations of making measurements in the limited membrane areas of single vesicles or planar supported bilayers. Quantitative determination of ibuprofen partitioning is achieved by using the phospholipid acyl-chains of the within-particle bilayer as an internal standard. This approach is tested for measurements of pH-dependent partitioning of ibuprofen into both hybrid-lipid and supported-lipid bilayers within silica particles, and the results are compared with octanol-water partitioning and with partitioning into individual optically trapped phospholipid vesicle membranes. Additionally, the impact of ibuprofen partitioning on bilayer structure is evaluated for both within-particle model membranes and compared with the structural impacts of partitioning into vesicle lipid bilayers.

  2. Ureaplasma species and Mycoplasma hominis in cervical fluid of pregnancies complicated by preterm prelabor rupture of membranes.

    Science.gov (United States)

    Musilova, Ivana; Pliskova, Lenka; Kutova, Radka; Hornychova, Helena; Jacobsson, Bo; Kacerovsky, Marian

    2016-01-01

    To evaluate Ureaplasma species and Mycoplasma hominis DNA in the cervical fluid and their association with microbial invasion of the amniotic cavity (MIAC) and/or histological chorioamnionitis (HCA) in pregnancies complicated by preterm prelabor rupture of membranes (PPROM). A prospective study of 68 women with singleton pregnancies complicated by PPROM between 24(0/7) and 36(6/7) weeks was conducted. Cervical fluid and amniotic fluid were collected from all women at the time of admission. The Ureaplasma species and Mycoplasma hominis DNA in the cervical fluid were identified using specific real-time PCR. Ureaplasma species and Mycoplasma hominis DNA were identified in 59% (40/69) of the cervical fluid samples. Women with the presence of Ureaplasma species DNA with and without Mycoplasma hominis DNA in the cervical fluid had a higher rate of MIAC alone [35% (14/40) versus 11% (3/28); p = 0.02] and a higher rate of the presence of both MIAC and HCA [30% (12/40) versus 4% (1/28); p = 0.01] than women without Ureaplasma species and Mycoplasma hominis DNA in the cervical fluid. The presence of Ureaplasma species DNA with and without Mycoplasma hominis DNA in the cervical fluid is associated with a higher risk of MIAC or MIAC and HCA together in pregnancies complicated by PPROM.

  3. Liposomes as potential masking agents in sport doping. Part 1: analysis of phospholipids and sphingomyelins in drugs and biological fluids by aqueous normal-phase liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Esposito, Simone; Colicchia, Sonia; de la Torre, Xavier; Mazzarino, Monica; Botrè, Francesco

    2017-01-01

    In the present work, aqueous normal-phase liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS), in different acquisition modes, was employed for the direct analysis and profiling of nine phospholipid classes (phosphatidic acids, phosphatidylserines, phosphatidylethanolamines, lysophosphatidylethanolamines, phosphatidylglycerols, phosphatidylinositols, phosphatidylcholines, lysophosphatidylcholines, and sphingomyelins) in biological and pharmaceutical matrices. After chromatographic separation by a diol column, detection and elucidation of phospholipid and sphingomyelin classes and molecular species were performed by different scan acquisition modes. For screening analysis, molecular ions [M + H] + were detected in positive precursor ion scan of m/z 184 for the classes of phosphatidylcholines, lyso-phosphatidylcholines and sphingomyelins; while phosphatidylethanolamines and lyso-phosphatidylethanolamines were detected monitoring neutral loss scan of 141 Da; and phosphatidylserines detected using neutral loss scan of 184 Da. Molecular ions [M-H] - were instead acquired in negative precursor ion scan of m/z 153 for the classes of phosphatidic acids and phosphatidylglycerols; and of m/z 241 for the phosphatidylinositols. For the identification of the single molecular species, product ion scan mass spectra of the [M + HCOO] - ions for phosphatidylcholines and [M + H] + ions for the other phospholipids considered were determined for each class and compared with the fragmentation pattern of model phospholipid reference standard. By this approach, nearly 100 phospholipids and sphingomyelins were detected and identified. The optimized method was then used to characterize the phospholipid and sphingomyelin profiles in human plasma and urine samples and in two phospholipid-based pharmaceutical formulations, proving that it also allows to discriminate compounds of endogenous origin from those resulting from the intake of pharmaceutical products

  4. The membrane interaction of amphiphilic model peptides affects phosphatidylserine headgroup and acyl chain order and dynamics. Application of the phospholipid headgroup electrometer concept to phosphatidylserine

    International Nuclear Information System (INIS)

    de Kroon, A.I.P.M.; Killian, J.A.; de Gier, J.; de Kruijff, B.

    1991-01-01

    Deuterium nuclear magnetic resonance ( 2 H NMR) was used to study the interaction of amphiphilic model peptides with model membranes consisting of 1,2-dioleoyl-sn-glycero-3-phospho-L-serine deuterated either at the β-position of the serine moiety ([2- 2 H]DOPS) or at the 11-position of the acyl chains ([11,11- 2 H 2 ]DOPS). The peptides are derived from the sequences H-Ala-Met-Leu-Trp-Ala-OH and H-Arg-Met-Leu-Trp-Ala-OH and contain a positive charge of +1 or +2 at the amino terminus or one positive charge at each end of the molecule. Upon titration of dispersions of DOPS with the peptides, the divalent peptides show a similar extent of binding to the DOPS bilyers, which is larger than that of the single charged peptide. Under these conditions the values of the quadrupolar splitting of both [2- 2 H]DOPS and [11,11- 2 H 2 ]DOPS are decreased, indicating that the peptides reduce the order of both the DOPS headgroup and the acyl chains. The extent of the decrease depends on the amount of peptide bound and on the position of the charged moieties in the peptide molecule. Titrations of DOPS with poly(L-lysine) 100 , which were included for reasons of comparison, reveal increased Δv q values. When the peptide-lipid titrations are carried out without applying a freeze-thaw procedure to achieve full equilibration, two-component 2 H NMR spectra occur. The apparently limited accessibility of the lipid to the peptides under these circumstances is discussed in relation to the ability of the peptides to exhibit transbilayer movement. 2 H spin-lattice relaxation time T1 measurements demonstrate a decrease of the rates of motion of both headgroup and acyl chains of DOPS in the presence of the peptides

  5. The GacS/A-RsmA Signal Transduction Pathway Controls the Synthesis of Alkylresorcinol Lipids that Replace Membrane Phospholipids during Encystment of Azotobacter vinelandii SW136.

    Directory of Open Access Journals (Sweden)

    Yanet Romero

    Full Text Available Azotobacter vinelandii is a soil bacterium that undergoes a differentiation process that forms cysts resistant to desiccation. During encystment, a family of alkylresorcinols lipids (ARs are synthesized and become part of the membrane and are also components of the outer layer covering the cyst, where they play a structural role. The synthesis of ARs in A. vinelandii has been shown to occur by the activity of enzymes encoded in the arsABCD operon. The expression of this operon is activated by ArpR, a LysR-type transcriptional regulator whose transcription occurs during encystment and is dependent on the alternative sigma factor RpoS. In this study, we show that the two component response regulator GacA, the small RNA RsmZ1 and the translational repressor protein RsmA, implicated in the control of the synthesis of other cysts components (i.e., alginate and poly-ß-hydroxybutyrate, are also controlling alkylresorcinol synthesis. This control affects the expression of arsABCD and is exerted through the regulation of arpR expression. We show that RsmA negatively regulates arpR expression by binding its mRNA, repressing its translation. GacA in turn, positively regulates arpR expression through the activation of transcription of RsmZ1, that binds RsmA, counteracting its repressor activity. This regulatory cascade is independent of RpoS. We also show evidence suggesting that GacA exerts an additional regulation on arsABCD expression through an ArpR independent route.

  6. LCA of Egg Phospholipids

    OpenAIRE

    Berggren, Anders

    2013-01-01

    Egg phospholipids are a group of fats or lipids in the egg yolk, commonly used as emulsifiers in the chemical industry to facilitate the dissolving of substances. The pharmaceutical company Fresenius-Kabi manufactures this product and seeks a better understanding of the product’s major environmental impacts in order to comply with the ISO 14001 requirements, communicate its environmental performance and choose raw materials that result in lower environmental impacts. The aim of this study is ...

  7. Lipidomics and H218O labeling techniques reveal increased remodeling of DHA-containing membrane phospholipids associated with abnormal locomotor responses in α-tocopherol deficient zebrafish (danio rerio embryos

    Directory of Open Access Journals (Sweden)

    Melissa Q. McDougall

    2016-08-01

    Full Text Available We hypothesized that vitamin E (α-tocopherol is required by the developing embryonic brain to prevent depletion of highly polyunsaturated fatty acids, especially docosahexaenoic acid (DHA, 22:6, the loss of which we predicted would underlie abnormal morphological and behavioral outcomes. Therefore, we fed adult 5D zebrafish (Danio rerio defined diets without (E− or with added α-tocopherol (E+, 500 mg RRR-α-tocopheryl acetate/kg diet for a minimum of 80 days, and then spawned them to obtain E− and E+ embryos. The E− compared with E+ embryos were 82% less responsive (p<0.01 to a light/dark stimulus at 96 h post-fertilization (hpf, demonstrating impaired locomotor behavior, even in the absence of gross morphological defects. Evaluation of phospholipid (PL and lysophospholipid (lyso-PL composition using untargeted lipidomics in E− compared with E+ embryos at 24, 48, 72, and 120 hpf showed that four PLs and three lyso-PLs containing docosahexaenoic acid (DHA, including lysophosphatidylcholine (LPC 22:6, required for transport of DHA into the brain, p<0.001, were at lower concentrations in E− at all time-points. Additionally, H218O labeling experiments revealed enhanced turnover of LPC 22:6 (p<0.001 and three other DHA-containing PLs in the E− compared with the E+ embryos, suggesting that increased membrane remodeling is a result of PL depletion. Together, these data indicate that α-tocopherol deficiency in the zebrafish embryo causes the specific depletion and increased turnover of DHA-containing PL and lyso-PLs, which may compromise DHA delivery to the brain and thereby contribute to the functional impairments observed in E− embryos.

  8. Structure and mechanism of ATP-dependent phospholipid transporters

    DEFF Research Database (Denmark)

    Lopez Marques, Rosa Laura; Poulsen, Lisbeth Rosager; Bailly, Aurélien

    2015-01-01

    Background ATP-binding cassette (ABC) transporters and P4-ATPases are two large and seemingly unrelated families of primary active pumps involved in moving phospholipids from one leaflet of a biological membrane to the other. Scope of review This review aims to identify common mechanistic features...... in the way phospholipid flipping is carried out by two evolutionarily unrelated families of transporters. Major conclusions Both protein families hydrolyze ATP, although they employ different mechanisms to use it, and have a comparable size with twelve transmembrane segments in the functional unit. Further......, despite differences in overall architecture, both appear to operate by an alternating access mechanism and during transport they might allow access of phospholipids to the internal part of the transmembrane domain. The latter feature is obvious for ABC transporters, but phospholipids and other hydrophobic...

  9. Use of Extracorporeal Membrane Oxygenation in a Fulminant Course of Amniotic Fluid Embolism Syndrome Immediately after Cesarean Delivery

    Directory of Open Access Journals (Sweden)

    Jae Ha Lee

    2016-08-01

    Full Text Available Amniotic fluid embolism is rare but is one of the most catastrophic complications in the peripartum period. This syndrome is caused by a maternal anaphylactic reaction to the introduction of fetal material into the pulmonary circulation. When amniotic fluid embolism is suspected, the immediate application of extracorporeal mechanical circulatory support such as veno-arterial extracorporeal membrane oxygenation (ECMO or cardiopulmonary bypass should be considered. Without the application of extracorporeal mechanical circulatory support, medical supportive care might not be sufficient to maintain cardiopulmonary stabilization in severe cases of amniotic fluid embolism. In this report, we present the case of a 36-year-old pregnant woman who developed an amniotic fluid embolism immediately after a cesarean section. Her catastrophic event started with the sudden onset of severe hypoxia, followed by circulatory collapse within 8 minutes. The veno-arterial mode of extracorporeal membrane oxygenation was initiated immediately. She was successfully resuscitated but with impaired cognitive function. Thus, urgent ECMO should be considered when amniotic fluid embolism syndrome is suspected in patients presenting acute cardiopulmonary collapse.

  10. Antioxidant Vitamin Status in the Serum and Amniotic Fluid of Women with Premature Rupture of the Fetal Membranes.

    Science.gov (United States)

    Barrett, Bridget M.

    The purpose of this study was to examine the status of antioxidant vitamins in women with premature rupture of the fetal membranes. Specimens of blood and amniotic fluid were obtained from 80 pregnant subjects included both smokers and non-smokers during the third trimester. The concentrations of ascorbic acid (ASA), beta -carotene, retinol and alpha -tocopherol in serum and amniotic fluid were determined. The experimental group consisted of those subjects with PROM while the control subjects were those with normal pregnancy. No statistical differences were found between the PROM and control groups in retinol and vitamin E concentrations in amniotic fluid and serum. Serum ASA concentrations of PROM subjects were not different from controls, but the PROM subjects had significantly lower amniotic fluid ASA concentrations. However, in a study with fewer subjects a lower serum ASA concentration in the PROM subjects was observed. The ratio of amniotic fluid ASA concentration to ASA serum concentration was significantly lower in PROM patients than in controls in both studies. This suggests that low levels of ASA in the amniotic fluid, but not in serum is better associated with PROM. A low amniotic fluid concentration of ASA may reflect an inefficient transfer and/or increased fetal utilization. Alterations in ASA concentration in the amniotic fluid may affect the integrity of the chorioamnion leading to PROM. beta -Carotene was not found in the amniotic fluid. Serum beta-carotene levels were significantly lower in the PROM group compared to the control group. Low concentrations of beta-carotene in maternal serum in smokers not only associated with poor maternal outcome (PROM) but also compromised the fetal outcome (decreased birth weight). Maintenance of adequate serum beta-carotene concentration and amniotic fluid ASA in smokers may result in better maternal and fetal outcome. This study demonstrated that nutrition is an important factor in the prevention of PROM.

  11. Formation and Regulation of Mitochondrial Membranes

    Directory of Open Access Journals (Sweden)

    Laila Cigana Schenkel

    2014-01-01

    Full Text Available Mitochondrial membrane phospholipids are essential for the mitochondrial architecture, the activity of respiratory proteins, and the transport of proteins into the mitochondria. The accumulation of phospholipids within mitochondria depends on a coordinate synthesis, degradation, and trafficking of phospholipids between the endoplasmic reticulum (ER and mitochondria as well as intramitochondrial lipid trafficking. Several studies highlight the contribution of dietary fatty acids to the remodeling of phospholipids and mitochondrial membrane homeostasis. Understanding the role of phospholipids in the mitochondrial membrane and their metabolism will shed light on the molecular mechanisms involved in the regulation of mitochondrial function and in the mitochondrial-related diseases.

  12. Survey of Pregnancy Outcome in Preterm Premature Rupture of Membranes with Amniotic Fluid Index <5 and ≥5

    Directory of Open Access Journals (Sweden)

    Fatemeh Tavassoli

    2010-04-01

    Full Text Available Objectives: Preterm premature rupture of membranes (PPROM is among the most important causes of perinatal morbidity and mortality. The aim of this study is to survey the pregnancy outcomes in preterm premature rupture of membranes with an amniotic fluid index of 5.Methods: This prospective cohort study was performed on 137 pregnant women complicated by preterm premature rupture of membranes (PPROM with a gestational age of 28-34 weeks during October 2006 to October 2008. The patients were divided in two groups according to their amniotic fluid index; AFI<5 (77cases, AFI≥5 (60cases. The Chi-squared test for qualitative variables and T-student test for quantitative variables were used to analyze the results.Results: The results showed that there was no significant difference in terms of the number of pregnancies, gestational age at rupture of membranes and birthweight between the two groups. However, the results demonstrated that the patients with AFI<5 exhibited a significantly shorter latency period (p=0.049, a higher rate of cesarean due to fetal distress (p=0.008, a lower neonatal Apgar score in the first minute (p=0.0127 and a higher rate of neonatal death during the first week (p=0.045.Conclusion: Overall, PPROM with oligohydroamnios is associated with shorter latency, higher rate of C/S, higher rate of early neonatal death and lower neonatal Apgar.

  13. Neutron diffraction studies of amphipathic helices in phospholipid bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Bradshaw, J.P.; Gilchrist, P.J. [Univ. of Edinburgh (United Kingdom); Duff, K.C. [Univ. of Edinburgh Medical School (United Kingdom); Saxena, A.M. [Brookhaven National Laboratory, Upton, NY (United States)

    1994-12-31

    The structural feature which is thought to facilitate the interaction of many peptides with phospholipid bilayers is the ability to fold into an amphipathic helix. In most cases the exact location and orientation of this helix with respect to the membrane is not known, and may vary with factors such as pH and phospholipid content of the bilayer. The growing interest in this area is stimulated by indications that similar interactions can contribute to the binding of certain hormones to their cell-surface receptors. We have been using the techniques of neutron diffraction from stacked phospholipid bilayers in an attempt to investigate this phenomenon with a number of membrane-active peptides. Here we report some of our findings with three of these: the bee venom melittin; the hormone calcitonin; and a synthetic peptide representing the ion channel fragment of influenza A M2 protein.

  14. Neutron diffraction studies of amphipathic helices in phospholipid bilayers

    International Nuclear Information System (INIS)

    Bradshaw, J.P.; Gilchrist, P.J.; Duff, K.C.; Saxena, A.M.

    1994-01-01

    The structural feature which is thought to facilitate the interaction of many peptides with phospholipid bilayers is the ability to fold into an amphipathic helix. In most cases the exact location and orientation of this helix with respect to the membrane is not known, and may vary with factors such as pH and phospholipid content of the bilayer. The growing interest in this area is stimulated by indications that similar interactions can contribute to the binding of certain hormones to their cell-surface receptors. We have been using the techniques of neutron diffraction from stacked phospholipid bilayers in an attempt to investigate this phenomenon with a number of membrane-active peptides. Here we report some of our findings with three of these: the bee venom melittin; the hormone calcitonin; and a synthetic peptide representing the ion channel fragment of influenza A M2 protein

  15. Use of urea and creatinine levels in vaginal fluid for the diagnosis of preterm premature rupture of membranes and delivery interval after membrane rupture.

    Science.gov (United States)

    Gezer, Cenk; Ekin, Atalay; Golbasi, Ceren; Kocahakimoglu, Ceysu; Bozkurt, Umit; Dogan, Askin; Solmaz, Ulaş; Golbasi, Hakan; Taner, Cuneyt Eftal

    2017-04-01

    To determine whether urea and creatinine measurements in vaginal fluid could be used to diagnose preterm premature rupture of membranes (PPROM) and predict delivery interval after PPROM. A prospective study conducted with 100 pregnant women with PPROM and 100 healthy pregnant women between 24 + 0 and 36 + 6 gestational weeks. All patients underwent sampling for urea and creatinine concentrations in vaginal fluid at the time of admission. Receiver operator curve analysis was used to determine the cutoff values for the presence of PPROM and delivery within 48 h after PPROM. In multivariate logistic regression analysis, vaginal fluid urea and creatinine levels were found to be significant predictors of PPROM (p 6.7 mg/dl for urea and >0.12 mg/dl for creatinine. The optimal cutoff values for the detection of delivery within 48 h were >19.4 mg/dl for urea and >0.23 mg/dl for creatinine. Measurement of urea and creatinine levels in vaginal fluid is a rapid and reliable test for diagnosing and also for predicting delivery interval after PPROM.

  16. Fluid migration through geo-membrane seams and through the interface between geo-membrane and geo-synthetic clay liner

    International Nuclear Information System (INIS)

    Barroso, M.

    2005-03-01

    Composite liners are used to limit the contamination migration from landfills. Their successful performance is closely related with the geo-membrane as it provides the primary barrier to diffusive and advective transport of contaminants. Critical issues on the performance of the geo-membranes are the seams between geo-membrane panels and the inevitable defects resulting, for instance, from inadequate installation activities. In landfills, where high density polyethylene geo-membranes are usually used, seams are typically made by the thermal-hot dual wedge method. A literature review on quality control of the seams showed that, in situ, fluid-tightness of seams is evaluated in qualitative terms (pass/failure criteria), despite their importance to ensure appropriate performance of the geo-membranes as barriers. In addition, a synthesis of studies on geo-membrane defects indicated that defects varying in density from 0.7 to 15.3 per hectare can be found in landfills. Defects represent preferential flow paths for leachate. Various authors have developed analytical solutions and empirical equations for predicting the flow rate through composite liners due to defects in the geo-membrane. The validity of these methods for composite liners comprising a geo-membrane over a geo-synthetic clay liner (GCL) over a compacted clay liner (CCL) has never been studied from an experimental point of view. To address the problem of fluid migration through the geo-membrane seams, an attempt is made to provide a test method, herein termed as 'gas permeation pouch test', for assessing the quality of the thermal-hot dual wedge seams. This test consists of pressurizing the air channel formed by the double seam with a gas to a specific pressure and, then, measuring the decrease in pressure over time. From the pressure decrease, both the gas permeation coefficients, in steady state conditions, and the time constant, in unsteady state conditions, can be estimated. Experiments were carried out

  17. Cryo-transmission electron microscopy of a superstructure of fluid dioleoylphosphatidylcholine (DOPC) membranes

    DEFF Research Database (Denmark)

    Klösgen, B; Helfrich, W

    1997-01-01

    a porous technical membrane. Sampling and cryofixation took place at various times within 3 weeks after the preparation. From the micrographs we infer that the small fraction of vesicles enclosing one another develop passages (connections) between the bilayers. In contrast, the superstructure is basically...... a feature of disconnected membranes. Among its modifications are isolated membrane bends or folds and a grainy membrane texture with a minimal grain spacing of 4-6 nm. In the extruded dispersions the passages and the superstructure seem to be formed mostly within the first day. The fraction of smooth...

  18. Comparative Study of Pregnancy Outcome in Premature Rupture of Membranes With Amniotic Fluid Indices of less and more than 5

    Directory of Open Access Journals (Sweden)

    F Tavassoli

    2010-03-01

    Full Text Available Introduction: Preterm premature rupture of the membranes (PPROM is one of the most important causes of perinatal morbidity and mortality. The aim of this study was to evaluate pregnancy outcome in preterm premature rupture of the membranes with amniotic fluid index less than 5 and more than 5. Methods: This prospective study was performed on 137 pregnant women with gestational age of 28-34 weeks with PPROM from Oct 2006 to Oct 2008. The patients were divided in two groups according to amniotic fluid index: AFI<5 (77 cases, AFI≥5 (60 cases. Chi-square test was used for qualitative variables, while T-student test was used for quantitative test. Results: Both groups were similar with respect to number of pregnancies, gestational age at rupture of the membranes and birth weight. In the group with AFI<5, applied latency was significantly shorter (PV=0.049, rate of cesarean section was higher due to fetal distress (PV=0.008, neonatal Apgar score in first minute was lower during the first week (PV=0.0127 and the rate of neonatal death was higher (PV=0.045 during the first week. Conclusion: An AFI<5 cm after PPROM is associated with earlier delivery, higher rate of cesarean due to fetal distress, higher rate of neonatal death, and lower neonatal Apgar score in first minute during the first week

  19. Mass transfer, fluid flow and membrane properties in flat and corrugated plate hyperfiltration modules

    NARCIS (Netherlands)

    Racz, I.G.; Groot Wassink, J.; Klaassen, R.

    1986-01-01

    Concentration polarisation, decreasing the efficiency in membrane separation processes, can be reduced by increasing mass transfer between membrane surface and bulk of the feed stream. Analogous to techniques used in plate heat exchangers efforts have been made to enhance mass transfer in a plate

  20. Characterization of Phospholipids in Insulin Secretory Granules and Mitochondria in Pancreatic Beta Cells and Their Changes with Glucose Stimulation*

    Science.gov (United States)

    MacDonald, Michael J.; Ade, Lacmbouh; Ntambi, James M.; Ansari, Israr-Ul H.; Stoker, Scott W.

    2015-01-01

    The lipid composition of insulin secretory granules (ISG) has never previously been thoroughly characterized. We characterized the phospholipid composition of ISG and mitochondria in pancreatic beta cells without and with glucose stimulation. The phospholipid/protein ratios of most phospholipids containing unsaturated fatty acids were higher in ISG than in whole cells and in mitochondria. The concentrations of negatively charged phospholipids, phosphatidylserine, and phosphatidylinositol in ISG were 5-fold higher than in the whole cell. In ISG phosphatidylserine, phosphatidylinositol, phosphatidylethanolamine, and sphingomyelin, fatty acids 12:0 and 14:0 were high, as were phosphatidylserine and phosphatidylinositol containing 18-carbon unsaturated FA. With glucose stimulation, the concentration of many ISG phosphatidylserines and phosphatidylinositols increased; unsaturated fatty acids in phosphatidylserine increased; and most phosphatidylethanolamines, phosphatidylcholines, sphingomyelins, and lysophosphatidylcholines were unchanged. Unsaturation and shorter fatty acid length in phospholipids facilitate curvature and fluidity of membranes, which favors fusion of membranes. Recent evidence suggests that negatively charged phospholipids, such as phosphatidylserine, act as coupling factors enhancing the interaction of positively charged regions in SNARE proteins in synaptic or secretory vesicle membrane lipid bilayers with positively charged regions in SNARE proteins in the plasma membrane lipid bilayer to facilitate docking of vesicles to the plasma membrane during exocytosis. The results indicate that ISG phospholipids are in a dynamic state and are consistent with the idea that changes in ISG phospholipids facilitate fusion of ISG with the plasma membrane-enhancing glucose-stimulated insulin exocytosis. PMID:25762724

  1. Characterization of phospholipids in insulin secretory granules and mitochondria in pancreatic beta cells and their changes with glucose stimulation.

    Science.gov (United States)

    MacDonald, Michael J; Ade, Lacmbouh; Ntambi, James M; Ansari, Israr-Ul H; Stoker, Scott W

    2015-04-24

    The lipid composition of insulin secretory granules (ISG) has never previously been thoroughly characterized. We characterized the phospholipid composition of ISG and mitochondria in pancreatic beta cells without and with glucose stimulation. The phospholipid/protein ratios of most phospholipids containing unsaturated fatty acids were higher in ISG than in whole cells and in mitochondria. The concentrations of negatively charged phospholipids, phosphatidylserine, and phosphatidylinositol in ISG were 5-fold higher than in the whole cell. In ISG phosphatidylserine, phosphatidylinositol, phosphatidylethanolamine, and sphingomyelin, fatty acids 12:0 and 14:0 were high, as were phosphatidylserine and phosphatidylinositol containing 18-carbon unsaturated FA. With glucose stimulation, the concentration of many ISG phosphatidylserines and phosphatidylinositols increased; unsaturated fatty acids in phosphatidylserine increased; and most phosphatidylethanolamines, phosphatidylcholines, sphingomyelins, and lysophosphatidylcholines were unchanged. Unsaturation and shorter fatty acid length in phospholipids facilitate curvature and fluidity of membranes, which favors fusion of membranes. Recent evidence suggests that negatively charged phospholipids, such as phosphatidylserine, act as coupling factors enhancing the interaction of positively charged regions in SNARE proteins in synaptic or secretory vesicle membrane lipid bilayers with positively charged regions in SNARE proteins in the plasma membrane lipid bilayer to facilitate docking of vesicles to the plasma membrane during exocytosis. The results indicate that ISG phospholipids are in a dynamic state and are consistent with the idea that changes in ISG phospholipids facilitate fusion of ISG with the plasma membrane-enhancing glucose-stimulated insulin exocytosis. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  2. Theoretical studies on membrane-based gas separation using computational fluid dynamics (CFD) of mass transfer

    International Nuclear Information System (INIS)

    Sohrabi, M.R.; Marjani, A.; Davallo, M.; Moradi, S.; Shirazian, S.

    2011-01-01

    A 2D mass transfer model was developed to study carbon dioxide removal by absorption in membrane contactors. The model predicts the steady state absorbent and carbon dioxide concentrations in the membrane by solving the conservation equations. The continuity equations for three sub domains of the membrane contactor involving the tube; membrane and shell were obtained and solved by finite element method (FEM). The model was based on 'non-wetted mode' in which the gas phase filled the membrane pores. Laminar parabolic velocity profile was used for the liquid flow in the tube side; whereas, the gas flow in the shell side was characterized by Happel's free surface model. Axial and radial diffusion transport inside the shell, through the membrane, and within the tube side of the contactor was considered in the mass transfer model. The predictions of percent CO/sub 2/ removal obtained by modeling were compared with the experimental values obtained from literature. They were the experimental results for CO/sub 2/ removal from CO/sub 2//N/sub 2/ gas mixture with amines aqueous solutions as the liquid solvent using polypropylene membrane contactor. The modeling predictions were in good agreement with the experimental values for different values of gas and liquid flow rates. (author)

  3. An extended study of the phase separation between phospholipids and grafted polymers on a bilayer biomembrane

    Energy Technology Data Exchange (ETDEWEB)

    Benhamou, M; Joudar, I; Kaidi, H; Elhasnaoui, K; Ridouane, H; Qamar, H, E-mail: benhamou.mabrouk@gmail.com [Laboratoire de Physique des Polymeres et Phenomenes Critiques, Faculte des Sciences, Ben M' sik, PO Box 7955, Casablanca (Morocco)

    2011-06-01

    We re-examine here the phase separation between phospholipids and adsorbed polymer chains on a fluid membrane with a change in some suitable parameter (temperature). Our purpose is to quantify the significant effects of the solvent quality and of the polydispersity of adsorbed loops formed by grafted polymer chains on the segregation phenomenon. To this end, we elaborate on a theoretical model that allows us to derive the expression for the mixing free energy. From this, we extract the phase diagram shape in the composition-temperature plane. Our main conclusion is that the polymer chain condensation is very sensitive to the solvent quality and to the polydispersity of loops of adsorbed chains.

  4. Prophylactic transabdominal amnioinfusion in oligohydramnios for preterm premature rupture of membranes: increase of amniotic fluid index during latency period.

    Science.gov (United States)

    Garzetti, G G; Ciavattini, A; De Cristofaro, F; La Marca, N; Arduini, D

    1997-01-01

    This study was designed to: (i) evaluate the effect of amnioinfusion on the latency period in patients with oligohydramnios for preterm premature rupture of membranes, and (ii) to investigate the relationship between changes in the amniotic fluid index and fetal heart rate short-term variability by computerized Hewlett-Packard cardiotocography, longitudinally estimated before and after prophylactic amnioinfusion. All singleton pregnancies with prolonged premature rupture of membranes after 25 weeks of gestation and seen at the Institute of Obstetrics and Gynecology, University of Ancona (Italy), between January 1994 and June 1995 were included in the study. Transabdominal amnioinfusion with 150-350 ml warmed normal saline (25-50 ml/min) was performed at weekly intervals. Amniotic fluid volume was assessed ultrasonographically by means of the four-quadrant technique on a weekly basis before and after each amnioinfusion, as well as the short-term variability by a Hewlett-Packard computerized cardiotocographic system. 18 women were enrolled and underwent prophylactic transabdominal amnioinfusion at weekly intervals until delivery. Eighteen controls, who did not undergo prophylactic amnioinfusion, were recruited from our 1992-1993 series and included in the study. The median interval between premature rupture of membranes and delivery was 3.0 weeks (range 1-8 weeks), with an average delivery age of 33.0 weeks (range 27-36 weeks). The latency period was significantly longer in patients who underwent prophylactic amnioinfusion (mean +/- SD, 4.1 +/- 1.7 weeks) than in controls(1.7 +/- 1.0 weeks; p amnioinfusion. A direct relationship was observed between the amniotic fluid index and short-term variability (linear regression analysis r = 0.54, p = 0.04). The mean values of fetal movements recorded by computerized tomography during the 20 min of observation significantly increased after amnioinfusion in comparison with those before it (2.6 +/- 0.9 and 0.9 +/- 0

  5. Influence of membrane composition on its flexibility

    International Nuclear Information System (INIS)

    Gerbelli, B.B.; Teixeira da Silva, E.R.; Oliveira, C.L.P.; Oliveira, E.A.

    2012-01-01

    Full text: Lamellar phases and vesicles composed of lipids have been used as model systems to investigate biological process related to cell membrane as well as promising carriers for drugs and gene therapy. The composition of the membrane determines its three dimensional shape and its properties such as rigidity and compressibility which play an important role on membrane fusion, protein adhesion, interactions between proteins, etc. We present systematic study of a lamellar system composed mainly of lecithin which is a biocompatible phospholipid and simusol, which is a mixture of fatty acids that acts as a cosurfactant introducing flexibility to the membrane. Using X ray scattering we determine the lamellar periodicity as a function of the hydration for different formulations of the membrane; ranging from 100 % to 50 % mass fraction of lecithin. The X-ray spectra are fitted using a 4 Gaussian model [1]that allows us to determine the lamellar periodicity and the Caille parameter [2]. The ideal swelling law relating the membrane volume fraction (φ m ) to the lamellar periodicity (D) is given by φ m =δ m /D, where δ m is the thickness membrane, however, when steric interactions are dominant with respect to electrostatic and van der Waals interactions, deviations from this behavior are expected [3]. We present experimental data illustrating the swelling behavior for the membrane compositions and the respective behavior of the hydration limit, membrane Luzzati [4], of the Caille parameter and qualitative interpretation of the interaction forces the systems studying the parameter membrane square amplitude fluctuation[5]. [1] Private communication with Prof. Dr. Cristiano Luis Pinto de Oliveira. [2] Caille A. et all, Acad. Sci. Paris B274 (1972) 891. [3] E. Kurtisovski et all, PRL 98, 258103 (2007). [4] Nagle et all, Curr Opin Struct Biol. 2000 Aug;10(4):474-80. [5] H. I. Petrache. Structure and interactions of fluid phospholipids bilayers measured by high resolution

  6. Lipid membrane partitioning of lysolipids and fatty acids: Effects of membrane phase structure and detergent chain length

    DEFF Research Database (Denmark)

    Høyrup, Lise Pernille Kristine; Davidsen, Jesper; Jørgensen, Kent

    2001-01-01

    gel phase and at high temperatures in the disordered fluid phase of the phospholipid membrane vesicles. The long saturated acyl chains of the lysolipids and fatty acids varied from 10 to 16 carbon atoms and all titrations were performed below the critical micellar concentrations (cmc...... of magnitude higher when the saturated acyl chain of the detergents increases by two carbon atoms. The obtained partition coefficients are of importance in relation to a deeper understanding of the interplay between global aqueous and local membrane concentrations of the detergents and the functional influence...

  7. Possible mechanism of adhesion in a mica supported phospholipid bilayer

    International Nuclear Information System (INIS)

    Pertsin, Alexander; Grunze, Michael

    2014-01-01

    Phospholipid bilayers supported on hydrophilic solids like silica and mica play a substantial role in fundamental studies and technological applications of phospholipid membranes. In both cases the molecular mechanism of adhesion between the bilayer and the support is of primary interest. Since the possibilities of experimental methods in this specific area are rather limited, the methods of computer simulation acquire great importance. In this paper we use the grand canonical Monte Carlo technique and an atomistic force field to simulate the behavior of a mica supported phospholipid bilayer in pure water as a function of the distance between the bilayer and the support. The simulation reveals a possible adhesion mechanism, where the adhesion is due to individual lipid molecules that protrude from the bilayer and form widely spaced links with the support. Simultaneously, the bilayer remains separated from the bilayer by a thin water interlayer which maintains the bilayer fluidity

  8. Electrokinetic migration across artificial liquid membranes. New concept for rapid sample preparation of biological fluids.

    Science.gov (United States)

    Pedersen-Bjergaard, Stig; Rasmussen, Knut Einar

    2006-03-24

    Basic drug substances were transported across a thin artificial organic liquid membrane by the application of 300 V d.c. From a 300 microl aqueous donor compartment (containing 10 mM HCl), the drugs migrated through a 200 microm artificial liquid membrane of 2-nitrophenyl octyl ether immobilized in the pores of a polypropylene hollow fiber, and into a 30 microl aqueous acceptor solution of 10 mM HCl inside the lumen of the hollow fiber. The transport was forced by an electrical potential difference sustained over the liquid membrane, resulting in electrokinetic migration of drug substances from the donor compartment to the acceptor solution. Within 5 min of operation at 300 V, pethidine, nortriptyline, methadone, haloperidol, and loperamide were extracted with recoveries in the range 70-79%, which corresponded to enrichments in the range 7.0-7.9. The chemical composition of the organic liquid membrane strongly affected the permeability, and may serve as an efficient tool for controlling the transport selectivity. Water samples, human plasma, and human urine were successfully processed, and in light of the present report, electrokinetic migration across thin artificial liquid membranes may be an interesting tool for future isolation within chemical analysis.

  9. Pseudomonas aeruginosa outer membrane vesicles triggered by human mucosal fluid and lysozyme can prime host tissue surfaces for bacterial adhesion

    Directory of Open Access Journals (Sweden)

    Matteo Maria Emiliano Metruccio

    2016-06-01

    Full Text Available Pseudomonas aeruginosa is a leading cause of human morbidity and mortality that often targets epithelial surfaces. Host immunocompromise, or the presence of indwelling medical devices, including contact lenses, can predispose to infection. While medical devices are known to accumulate bacterial biofilms, it is not well understood why resistant epithelial surfaces become susceptible to P. aeruginosa. Many bacteria, including P. aeruginosa, release Outer Membrane Vesicles (OMVs in response to stress that can fuse with host cells to alter their function. Here, we tested the hypothesis that mucosal fluid can trigger OMV release to compromise an epithelial barrier. This was tested using tear fluid and corneal epithelial cells in vitro and in vivo. After 1 h both human tear fluid, and the tear component lysozyme, greatly enhanced OMV release from P. aeruginosa strain PAO1 compared to PBS controls (~100 fold. TEM and SDS-PAGE showed tear fluid and lysozyme-induced OMVs were similar in size and protein composition, but differed from biofilm-harvested OMVs, the latter smaller with fewer proteins. Lysozyme-induced OMVs were cytotoxic to human corneal epithelial cells in vitro and murine corneal epithelium in vivo. OMV exposure in vivo enhanced Ly6G/C expression at the corneal surface, suggesting myeloid cell recruitment, and primed the cornea for bacterial adhesion (~4-fold, P < 0.01. Sonication disrupted OMVs retained cytotoxic activity, but did not promote adhesion, suggesting the latter required OMV-mediated events beyond cell killing. These data suggest that mucosal fluid induced P. aeruginosa OMVs could contribute to loss of epithelial barrier function during medical device-related infections.

  10. Influence of ethanol as bore fluid component on the morphological structure and performance of PES hollow fiber membrane for oil in water separation

    Energy Technology Data Exchange (ETDEWEB)

    Otitoju, Tunmise Ayode; Ahmad, Abdul Latif; Ooi, Boon Seng [Universiti Sains Malaysia, Penang (Malaysia)

    2017-10-15

    The relationships among varying bore fluid compositions containing ethanol/water were studied. The ethanol composition was varied in the ratio of 0%, 25%, 50%, 75% and 100%. The membrane dope solutions were prepared from 17.25 wt% polyethersulfone (PES), 0.75 wt% polyethylene glycol (PEG), 3 wt% silicon dioxide sol and 78.25 wt% of 1-methyl-2-pyrrolidone (NMP) via dry-jet spinning process. The membranes’ morphology as a result of varying ethanol ratio in the bore fluid composition was characterized and their effects on crude oil/water emulsion separation were evaluated. Results show that the membrane pore size and porosity decreased with increasing ethanol content in the bore fluid mixture, whereas the inner wall thickness of fibers increased. Furthermore, an increase in ethanol concentration also resulted in a slight increase in water contact angle. The use of 100/0 of ethanol/water resulted in UF membranes with the lowest performance. On the other hand, bore fluid mixture containing 25/75 ethanol/water produced membrane with the best performance for crude oil/water separation. Overall, the use of bore fluid mixture containing 25/75 ethanol/water mixture was found to be a powerful way to tune the morphological properties and performance of HF membrane.

  11. Influence of ethanol as bore fluid component on the morphological structure and performance of PES hollow fiber membrane for oil in water separation

    International Nuclear Information System (INIS)

    Otitoju, Tunmise Ayode; Ahmad, Abdul Latif; Ooi, Boon Seng

    2017-01-01

    The relationships among varying bore fluid compositions containing ethanol/water were studied. The ethanol composition was varied in the ratio of 0%, 25%, 50%, 75% and 100%. The membrane dope solutions were prepared from 17.25 wt% polyethersulfone (PES), 0.75 wt% polyethylene glycol (PEG), 3 wt% silicon dioxide sol and 78.25 wt% of 1-methyl-2-pyrrolidone (NMP) via dry-jet spinning process. The membranes’ morphology as a result of varying ethanol ratio in the bore fluid composition was characterized and their effects on crude oil/water emulsion separation were evaluated. Results show that the membrane pore size and porosity decreased with increasing ethanol content in the bore fluid mixture, whereas the inner wall thickness of fibers increased. Furthermore, an increase in ethanol concentration also resulted in a slight increase in water contact angle. The use of 100/0 of ethanol/water resulted in UF membranes with the lowest performance. On the other hand, bore fluid mixture containing 25/75 ethanol/water produced membrane with the best performance for crude oil/water separation. Overall, the use of bore fluid mixture containing 25/75 ethanol/water mixture was found to be a powerful way to tune the morphological properties and performance of HF membrane.

  12. Amoeboid swimming: a generic self-propulsion of cells in fluids by means of membrane deformations.

    Science.gov (United States)

    Farutin, Alexander; Rafaï, Salima; Dysthe, Dag Kristian; Duperray, Alain; Peyla, Philippe; Misbah, Chaouqi

    2013-11-27

    Microorganisms, such as bacteria, algae, or spermatozoa, are able to propel themselves forward thanks to flagella or cilia activity. By contrast, other organisms employ pronounced changes of the membrane shape to achieve propulsion, a prototypical example being the Eutreptiella gymnastica. Cells of the immune system as well as dictyostelium amoebas, traditionally believed to crawl on a substratum, can also swim in a similar way. We develop a model for these organisms: the swimmer is mimicked by a closed incompressible membrane with force density distribution (with zero total force and torque). It is shown that fast propulsion can be achieved with adequate shape adaptations. This swimming is found to consist of an entangled pusher-puller state. The autopropulsion distance over one cycle is a universal linear function of a simple geometrical dimensionless quantity A/V(2/3) (V and A are the cell volume and its membrane area). This study captures the peculiar motion of Eutreptiella gymnastica with simple force distribution.

  13. Validation of computational non-Newtonian fluid model for membrane bioreactor

    DEFF Research Database (Denmark)

    Sørensen, Lasse; Bentzen, Thomas Ruby; Skov, Kristian

    2015-01-01

    Membrane bioreactor (MBR) systems are often considered as the wastewater treatment method of the future due to its high effluent quality. One of the main problems with such systems is a relative large energy consumption, which has led to research in this specific area. A powerful tool for optimiz......Membrane bioreactor (MBR) systems are often considered as the wastewater treatment method of the future due to its high effluent quality. One of the main problems with such systems is a relative large energy consumption, which has led to research in this specific area. A powerful tool...

  14. Nanowire-integrated microporous silicon membrane for continuous fluid transport in micro cooling device

    International Nuclear Information System (INIS)

    So, Hongyun; Pisano, Albert P.; Cheng, Jim C.

    2013-01-01

    We report an efficient passive micro pump system combining the physical properties of nanowires and micropores. This nanowire-integrated microporous silicon membrane was created to feed coolant continuously onto the surface of the wick in a micro cooling device to ensure it remains hydrated and in case of dryout, allow for regeneration of the system. The membrane was fabricated by photoelectrochemical etching to form micropores followed by hydrothermal growth of nanowires. This study shows a promising approach to address thermal management challenges for next generation electronic devices with absence of external power

  15. In-situ assessment of biofilm formation in submerged membrane system using optical coherence tomography and computational fluid dynamics

    KAUST Repository

    Fortunato, Luca

    2016-09-09

    This paper introduces a novel approach to study the biofouling development on gravity driven submerged membrane bioreactor (SMBR). The on-line monitoring of biofilm formation on a flat sheet membrane was conducted non-destructively using optical coherence tomography (OCT), allowing the in-situ investigation of the biofilm structure for 43 d. The OCT enabled to obtain a time-lapse of biofilm development on the membrane under the continuous operation. Acquired real-time information on the biofilm structure related to the change in the flux profile confirming the successful monitoring of the dynamic evolution of the biofouling layer. Four different phases were observed linking the permeate flux with the change of biofilm morphology. In particular, a stable flux of 2.1±0.1 L/m2 h was achieved with the achievement of steady biofilm morphology after 30 d of operation. Biofilm descriptors, such as thickness, biofilm area, macro-porosity and roughness (absolute and relative), were calculated for each OCT acquired scans. Interestingly, relative roughness was correlated with the flux decrease. Furthermore, the precise biofilm morphology obtained from the OCT scans was used in computational fluid dynamics (CFD) simulation to better understand the role of biofilm structure on the filtration mechanism. © 2016 Elsevier B.V.

  16. Adsorption of GST-PI3Kγ at the Air-Buffer Interface and at Substrate and Nonsubstrate Phospholipid Monolayers

    Science.gov (United States)

    Hermelink, Antje; Kirsch, Cornelia; Klinger, Reinhard; Reiter, Gerald; Brezesinski, Gerald

    2009-01-01

    The recruitment of phosphoinositide 3-kinase γ (PI3Kγ) to the cell membrane is a crucial requirement for the initiation of inflammation cascades by second-messenger production. In addition to identifying other regulation pathways, it has been found that PI3Kγ is able to bind phospholipids directly. In this study, the adsorption behavior of glutathione S-transferase (GST)-PI3Kγ to nonsubstrate model phospholipids, as well as to commercially available substrate inositol phospholipids (phosphoinositides), was investigated by use of infrared reflection-absorption spectroscopy (IRRAS). The nonsubstrate phospholipid monolayers also yielded important information about structural requirements for protein adsorption. The enzyme did not interact with condensed zwitterionic or anionic monolayers; however, it could penetrate into uncompressed fluid monolayers. Compression to values above its equilibrium pressure led to a squeezing out and desorption of the protein. Protein affinity for the monolayer surface increased considerably when the lipid had an anionic headgroup and contained an arachidonoyl fatty acyl chain in sn-2 position. Similar results on a much higher level were observed with substrate phosphoinositides. No structural response of GST-PI3Kγ to lipid interaction was detected by IRRAS. On the other hand, protein adsorption caused a condensing effect in phosphoinositide monolayers. In addition, the protein reduced the charge density at the interface probably by shifting the pK values of the phosphate groups attached to the inositol headgroups. Because of their strongly polar headgroups, an interaction of the inositides with the water molecules of the subphase can be expected. This interaction is disturbed by protein adsorption, causing the ionization state of the phosphates to change. PMID:19186139

  17. Adsorption of GST-PI3Kgamma at the air-buffer interface and at substrate and nonsubstrate phospholipid monolayers.

    Science.gov (United States)

    Hermelink, Antje; Kirsch, Cornelia; Klinger, Reinhard; Reiter, Gerald; Brezesinski, Gerald

    2009-02-01

    The recruitment of phosphoinositide 3-kinase gamma (PI3Kgamma) to the cell membrane is a crucial requirement for the initiation of inflammation cascades by second-messenger production. In addition to identifying other regulation pathways, it has been found that PI3Kgamma is able to bind phospholipids directly. In this study, the adsorption behavior of glutathione S-transferase (GST)-PI3Kgamma to nonsubstrate model phospholipids, as well as to commercially available substrate inositol phospholipids (phosphoinositides), was investigated by use of infrared reflection-absorption spectroscopy (IRRAS). The nonsubstrate phospholipid monolayers also yielded important information about structural requirements for protein adsorption. The enzyme did not interact with condensed zwitterionic or anionic monolayers; however, it could penetrate into uncompressed fluid monolayers. Compression to values above its equilibrium pressure led to a squeezing out and desorption of the protein. Protein affinity for the monolayer surface increased considerably when the lipid had an anionic headgroup and contained an arachidonoyl fatty acyl chain in sn-2 position. Similar results on a much higher level were observed with substrate phosphoinositides. No structural response of GST-PI3Kgamma to lipid interaction was detected by IRRAS. On the other hand, protein adsorption caused a condensing effect in phosphoinositide monolayers. In addition, the protein reduced the charge density at the interface probably by shifting the pK values of the phosphate groups attached to the inositol headgroups. Because of their strongly polar headgroups, an interaction of the inositides with the water molecules of the subphase can be expected. This interaction is disturbed by protein adsorption, causing the ionization state of the phosphates to change.

  18. Amnioinfusion in labor induction of term pregnancies with premature rupture of the membranes and low amniotic fluid.

    Science.gov (United States)

    Miño, M; Puertas, A; Herruzo, A J; Miranda, J A

    1998-05-01

    To analyze the utility of prophylactic amnioinfusion in term pregnancies with PROM and a low amniotic fluid index during labor induction. Forty-two women with amnioinfusion and 42 in a control group with amniotic fluid index (AFI) below 10 cm when admitted to labor induction were studied. All patients had electronic fetal heart rate and intrauterine pressure continuous monitoring. Amnioinfusion of normal saline (37 degrees C) was realized in the study group, using a continuous perfusion pump at 600 ml/h for 1 h, after which the AFI was again recorded; if this was amnioinfusion. Both groups were similar in age, primiparity, gestational age, initial AFI, interval from rupture of membranes until delivery and length of labor. The amnioinfusion of 600 ml in 1 h significantly increased the AFI (an increase of 7.2 +/- 3.9 vs. a decrease of 1.1 +/- 1.6, P amnioinfusion group, there was a significantly lower rate of cesarean deliveries (0 vs. 6, P amnioinfusion improves neonatal metabolic state when used in labor induction of term pregnancies with PROM and a low amniotic fluid index.

  19. Computational fluid dynamics simulations of flow and concentration polarization in forward osmosis membrane systems

    DEFF Research Database (Denmark)

    Gruber, M.F.; Johnson, C.J.; Tang, C.Y.

    2011-01-01

    is inspired by previously published CFD models for pressure-driven systems and the general analytical theory for flux modeling in asymmetric membranes. Simulations reveal a non-negligible external concentration polarization on the porous support, even when accounting for high cross-flow velocity and slip...

  20. Daptomycin inhibits cell envelope synthesis by interfering with fluid membrane microdomains

    NARCIS (Netherlands)

    Müller, A.; Wenzel, M.; Strahl, H.; Grein, F.; Saaki, T.N.V.; Kohl, B.; Siersma, T.; Bandow, J.E.; Sahl, H.-G.; Schneider, T.; Hamoen, L.W.

    2016-01-01

    Daptomycin is a highly efficient last-resort antibiotic that targets the bacterial cell membrane. Despite its clinical importance, the exact mechanism by which daptomycin kills bacteria is not fully understood. Different experiments have led to different models, including (i) blockage of cell wall

  1. Hydrophobic thickness of fluid planar monooleylglycerol membran maximally thinned by inversed micellisation

    DEFF Research Database (Denmark)

    Knudsen, P. J.; Mouritsen, Ole G.

    1999-01-01

    be measured by a capacitance technique assuming the relative permittivity of the hydrophobic part of the bilayer. Introduction of an AC microvolt technique allowed manufacture of stable thick membranes by quenching the electroconstriction observed when DC electrical potentials in the millivolt range are used...

  2. Salmeterol improves fluid clearance from alveolar-capillary membrane in COPD patients: a pilot study.

    Science.gov (United States)

    Di Marco, Fabiano; Guazzi, Marco; Sferrazza Papa, Giuseppe Francesco; Vicenzi, Marco; Santus, Pierachille; Busatto, Paolo; Piffer, Federico; Blasi, Francesco; Centanni, Stefano

    2012-02-01

    The cardiovascular component associated with chronic obstructive pulmonary disease (COPD) plays a major role in disease prognosis, accounting for 25% of the deaths. Experimental and initial clinical data suggest that beta-adrenergic agonists accelerate fluid clearance from the alveolar airspace, with potentially positive effects on cardiogenic and noncardiogenic pulmonary oedema. This pilot study investigated the acute effects of the long-acting beta-2 agonist, salmeterol, on alveolar fluid clearance after rapid saline intravenous infusion by evaluating diffusive and mechanical lung properties. Ten COPD and 10 healthy subjects were treated with salmeterol or placebo 4 h before the patient's mechanical and diffusive lung properties were measured during four non consecutive days, just before and after a rapid saline infusion, or during a similar period without an infusion. In both COPD and healthy subjects, rapid saline infusion with placebo or salmeterol premedication lead to a significant decrease in diffusion capacity for carbon monoxide (DLCO) and forced expiratory volume in 1 s (FEV1). Nonetheless, salmeterol pretreatment lead to a significantly reduced gas exchange impairment caused by saline infusion (-64% of DLCO reduction compared with placebo), whereas it did not affect changes in FEV1. In the control setting with no infusion, we found no significant change in either DLCO or mechanical properties of the lung. Salmeterol appears to provide a protective effect, not related to bronchodilation, against an acute alveolar fluid clearance challenge secondary to lung fluid overload in COPD patients. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Phospholipid composition and longevity: lessons from Ames dwarf mice.

    Science.gov (United States)

    Valencak, Teresa G; Ruf, Thomas

    2013-12-01

    Membrane fatty acid (FA) composition is correlated with longevity in mammals. The "membrane pacemaker hypothesis of ageing" proposes that animals which cellular membranes contain high amounts of polyunsaturated FAs (PUFAs) have shorter life spans because their membranes are more susceptible to peroxidation and further oxidative damage. It remains to be shown, however, that long-lived phenotypes such as the Ames dwarf mouse have membranes containing fewer PUFAs and thus being less prone to peroxidation, as would be predicted from the membrane pacemaker hypothesis of ageing. Here, we show that across four different tissues, i.e., muscle, heart, liver and brain as well as in liver mitochondria, Ames dwarf mice possess membrane phospholipids containing between 30 and 60 % PUFAs (depending on the tissue), which is similar to PUFA contents of their normal-sized, short-lived siblings. However, we found that that Ames dwarf mice membrane phospholipids were significantly poorer in n-3 PUFAs. While lack of a difference in PUFA contents is contradicting the membrane pacemaker hypothesis, the lower n-3 PUFAs content in the long-lived mice provides some support for the membrane pacemaker hypothesis of ageing, as n-3 PUFAs comprise those FAs being blamed most for causing oxidative damage. By comparing tissue composition between 1-, 2- and 6-month-old mice in both phenotypes, we found that membranes differed both in quantity of PUFAs and in the prevalence of certain PUFAs. In sum, membrane composition in the Ames dwarf mouse supports the concept that tissue FA composition is related to longevity.

  4. An articulated predictive model for fluid-free artificial basilar membrane as broadband frequency sensor

    Science.gov (United States)

    Ahmed, Riaz; Banerjee, Sourav

    2018-02-01

    In this article, an extremely versatile predictive model for a newly developed Basilar meta-Membrane (BM2) sensors is reported with variable engineering parameters that contribute to it's frequency selection capabilities. The predictive model reported herein is for advancement over existing method by incorporating versatile and nonhomogeneous (e.g. functionally graded) model parameters that could not only exploit the possibilities of creating complex combinations of broadband frequency sensors but also explain the unique unexplained physical phenomenon that prevails in BM2, e.g. tailgating waves. In recent years, few notable attempts were made to fabricate the artificial basilar membrane, mimicking the mechanics of the human cochlea within a very short range of frequencies. To explain the operation of these sensors a few models were proposed. But, we fundamentally argue the "fabrication to explanation" approach and proposed the model driven predictive design process for the design any (BM2) as broadband sensors. Inspired by the physics of basilar membrane, frequency domain predictive model is proposed where both the material and geometrical parameters can be arbitrarily varied. Broadband frequency is applicable in many fields of science, engineering and technology, such as, sensors for chemical, biological and acoustic applications. With the proposed model, which is three times faster than its FEM counterpart, it is possible to alter the attributes of the selected length of the designed sensor using complex combinations of model parameters, based on target frequency applications. Finally, the tailgating wave peaks in the artificial basilar membranes that prevails in the previously reported experimental studies are also explained using the proposed model.

  5. Soil-fluid-structure interaction applied to the Oued Taht dam (taking into account the membrane effect.

    Directory of Open Access Journals (Sweden)

    Nasreddine Krenich

    2018-01-01

    Full Text Available The objective of this work is to analyze the dynamic behavior (modal behavior of the "Oued Taht" arch dam located at MASCARA, taking into consideration the effect of soil-fluid-structure interaction. The finite element code "Ansys" was chosen for the dynamic modeling of the dam that is the subject of this study. Three hypotheses were used for soil-structure interaction modeling; model with embedded base which corresponds to the case where the phenomenon of interactions soil-structure is neglected, model with ground of foundation without mass which consists in taking into account the kinematic component of interaction soil structure and neglecting the inertial component and the model with foundation soil with mass where the two components of soil-structure interaction are taken into account. For the fluid, the model of added masses (equivalent to the westergaard approach using the SURF element available in the Ansys code library was used. A comparison between the different models of the "Oued Taht" dam was made; it has been found that the taking into account of the soil-fluid-structure interaction phenomenon modifies the period of the system and that the modeling of the dam with and without fluid gives a very important difference of the periods. The results obtained were compared with those of the "Brezina" dam, which is a gravity dam located in BAYADH. The work has shown that the periods of the "Oued Taht" dam with soil-fluid-structure interaction modeling are very out of phase with the periods without fluid modeling (taking into account only the soilstructure interaction phenomenon. which is not the case for the Brezina dam where the periods for the two models are getting closer. The periods between the two models mentioned before are close to the dam of Brézina because the latter is a dam which participates much more by its own weight than by its vault (thickness of the vault varies between 36.3 m at the base and 5m in crest which is the

  6. Evolution of phospholipid contents during the production of quark cheese from buttermilk.

    Science.gov (United States)

    Ferreiro, T; Martínez, S; Gayoso, L; Rodríguez-Otero, J L

    2016-06-01

    We report the evolution of phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidylcholine (PC), phosphatidylserine (PS), and sphingomyelin (SM) contents during the production of quark cheese from buttermilk by successive ultrafiltration concentration, enrichment with cream, concurrent homogenization and pasteurization, fermentative coagulation, and separation of quark from whey by further ultrafiltration. Buttermilk is richer than milk itself in phospholipids that afford desirable functional and technological properties, and is widely used in dairy products. To investigate how phospholipid content is affected by end-product production processes such as ultrafiltration, homogenization, pasteurization or coagulation, we measured the phospholipids at several stages of each of 5 industrial-scale quark cheese production runs. In each run, 10,000L of buttermilk was concentrated to half volume by ultrafiltration, enriched with cream, homogenized, pasteurized, inoculated with lactic acid bacteria, incubated to coagulation, and once more concentrated to half volume by ultrafiltration. Phospholipid contents were determined by HPLC with evaporative light scattering detection in the starting buttermilk, concentrated buttermilk, ultrafiltrate, cream-enriched concentrated buttermilk (both before and after concurrent homogenization and pasteurization), coagulate, and quark, and also in the rinsings obtained when the ultrafiltration equipment was washed following initial concentration. The average phospholipid content of buttermilk was approximately 5 times that of milk, and the phospholipid content of buttermilk fat 26 to 29 times that of milk fat. Although phospholipids did not cross ultrafiltration membranes, significant losses occurred during ultrafiltration (due to retention on the membranes) and during the homogenization and pasteurization process. During coagulation, however, phospholipid content rose, presumably as a consequence of the proliferation of the

  7. Antibiotic interaction with phospholipid monolayers

    International Nuclear Information System (INIS)

    Gambinossi, F.; Mecheri, B.; Caminati, G.; Nocentini, M.; Puggelli, M.; Gabrielli, G.

    2002-01-01

    We studied the interactions of tetracycline (TC) antibiotic molecules with phospholipid monolayers with the two-fold aim of elucidating the mechanism of action and providing a first step for the realization of bio-mimetic sensors for such drugs by means of the Langmuir-Blodgett technique. We examined spreading monolayers of three phospholipids in the presence of tetracycline in the subphase by means of surface pressure-area and surface potential-area isotherms as a function of bulk pH. We selected phospholipids with hydrophobic chains of the same length but polar head groups differing either in dimensions and protonation equilibria, i.e. dipalmitoylphosphatidylcholine (DPPC), dipalmitoylphosphatidylethanolamine (DPPE) and dipalmitoylphosphatidic acid (DPPA). The interaction of tetracycline with the three phospholipids was found to be highly dependent on the electric charge of the antibiotic and on the ionization state of the lipid. Significant interactions are established between the negatively charged form of dipalmitoylphosphatidic acid and the zwitterionic form of tetracycline. The drug was found to migrate at the interface where it is adsorbed underneath or/and among the head groups, depending on the surface pressure of the film, whereas penetration through the hydrophobic layer was excluded for all the three phospholipids

  8. Antibiotic interaction with phospholipid monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Gambinossi, F.; Mecheri, B.; Caminati, G.; Nocentini, M.; Puggelli, M.; Gabrielli, G

    2002-12-01

    We studied the interactions of tetracycline (TC) antibiotic molecules with phospholipid monolayers with the two-fold aim of elucidating the mechanism of action and providing a first step for the realization of bio-mimetic sensors for such drugs by means of the Langmuir-Blodgett technique. We examined spreading monolayers of three phospholipids in the presence of tetracycline in the subphase by means of surface pressure-area and surface potential-area isotherms as a function of bulk pH. We selected phospholipids with hydrophobic chains of the same length but polar head groups differing either in dimensions and protonation equilibria, i.e. dipalmitoylphosphatidylcholine (DPPC), dipalmitoylphosphatidylethanolamine (DPPE) and dipalmitoylphosphatidic acid (DPPA). The interaction of tetracycline with the three phospholipids was found to be highly dependent on the electric charge of the antibiotic and on the ionization state of the lipid. Significant interactions are established between the negatively charged form of dipalmitoylphosphatidic acid and the zwitterionic form of tetracycline. The drug was found to migrate at the interface where it is adsorbed underneath or/and among the head groups, depending on the surface pressure of the film, whereas penetration through the hydrophobic layer was excluded for all the three phospholipids.

  9. Vaginal Fluid hCG Levels for Detecting Premature Rupture of Membranes

    Directory of Open Access Journals (Sweden)

    T. Artimani

    2004-04-01

    Full Text Available The aim of this study was to determine whether there is any different in hCG levels of vaginal fluids from normal pregnant women, women with confirmed PROM and with suspected PROM. After irrigating the posterior vaginal fornix with 3 ml of sterile saline and procuring vaginal washing , we measured hCG levels. Samples were analyzed from 38 normal pregnant women , 31 women with confirmed PROM , 28 women with suspected PROM. The mean of vaginal fluid hCG levels of normal pregnant women were 11.2 (0.00-98.6 mIu/ml. That of women with PROM was 140.2 (0.5 , 390.1 and that of women with suspected PROM was 21.5 (0.0 , 143.9. Sensivity was 80%, specility 83% , positive predictive value 73.7% , negative predictive value 88.1% , using a cut-value 20. It was concluded that the hCG level in vaginal fluid is a marker of PROM during third trimester.

  10. Design and fabrication of PMMA-micromachined fluid lens based on electromagnetic actuation on PMMA–PDMS bonded membrane

    International Nuclear Information System (INIS)

    Lee, June Kyoo; Park, Kyung-Woo; Choi, Ju Chan; Kim, Hak-Rin; Kong, Seong Ho

    2012-01-01

    The fabrication of a poly(methyl methacrylate) (PMMA)-micromachined fluid lens with an optimally designed built-in electromagnetic actuator was demonstrated in this study. Through a finite element method, the number of winding turns and the distance between magnetic moments were estimated to design an effective and miniaturized electromagnetic actuator. The lens body composed of PMMA structures was simply and rapidly micromachined using computer numerical control micro-milling. The poly(dimethylsiloxane) (PDMS) membranes for electromagnetic actuation were bonded to the PMMA structures by using the proposed PMMA–PDMS bonding technique, which uses an SiO 2 intermediate layer. A physical repulsive force produced by the electromagnetic actuator applies a controllable fluidic pressure to a fluidic chamber that is sealed with the PDMS membrane, thus allowing dynamic focusing. The focus tunability of the fabricated lens was 67 diopters with a focus hysteresis of less than 1 mm and a response time of 2 ms. The solenoid of the built-in actuator showed negligible thermal crosstalk to the lens. (paper)

  11. Agarose gel electrophoresis of cerebrospinal fluid proteins of dogs after sample concentration using a membrane microconcentrator technique.

    Science.gov (United States)

    Gama, Fernanda Gomes Velasque; Santana, Aureo Evangelista; Filho, Eugênio de Campos; Nogueira, Cláudia Aparecida da Silva

    2007-03-01

    Cerebrospinal fluid (CSF) is produced in the cerebral ventricles through ultrafiltration of plasma and active transport mechanisms. Evaluation of proteins in CSF may provide important information about the production of immunoglobulins within the central nervous system as well as possible disturbances in the blood-brain barrier. The objective of this study was to measure the concentration and fractions of protein in CSF samples using a membrane microconcentrator technique followed by electrophoresis, and to compare the protein fractions obtained with those in serum. CSF samples from 3 healthy dogs and 3 dogs with canine distemper virus infection were concentrated using a membrane microconcentrator having a 0.5 to 30,000 d nominal molecular weight limit (Ultrafree, Millipore, Billerica, MA, USA). Protein concentration was determined before and after concentration. Agarose gel electrophoresis was done on concentrated CSF samples, serum, and serial dilutions of one of the CSF samples. Electrophoretic bands were clearly identified in densitometer tracings in CSF samples with protein concentrations as low as 1.3 g/dL. The higher CSF protein concentration in dogs with distemper was mainly the result of increased albumin concentration. The microconcentrating method used in this study enables characterization of the main protein fractions in CSF by routine electrophoresis and may be useful for interpreting the underlying cause of changes in CSF protein concentrations.

  12. The correlation between histologic placentitis and amnionitis and the amnioniotic fluid's inflammatory cytokines in case of spontaneous pre-term labor with intact membrane

    Directory of Open Access Journals (Sweden)

    Agus Abadi

    2001-12-01

    Full Text Available Pre-term labor is presumed to result from spreading of lower genital infection to upper part, subsequently to decidual and choioamniotic tissues. Host response to this injury include the expression of protein which is responsible to the inflammatory reactions. The expression of the inflammatory cytokines such as IL-1β, IL-6, IL-8 and TNF-α increase in case of infection.These cytokines may play an essential role in the pathophysiology of spontaneous pretem labor with intact membrane.An observational analytic cohort study was caried out on cases of spontaneous pre-tefln labor with intact membrane. The objectives of this study are to examine the relationship between l the histologic amnionitis and placentitis and the incidence of preterm delivery,2 the expression of amniotic fluid's IL-1β, IL-6, IL-8 and TNF-α and the incidence of preterm delivery, 3 the level of amniotic fluid's IL-1β, IL-6, IL-8 and TNF-α and the grade of histologic amnionitis and placentitis in case of pre-term labor with intact membrane. Cases of spontaneous Pre'teftn labor with intact membrane which underwent transabdominal amniocentesis at admission and managed as standard procedure for pre-term labor with intact membrane. Atl of the cases were observed until the delivery of the baby, eithir preterm or term. The membrane and the placentawere cut postnatally and then the histologic acute inflammation eyaluated based on the criteria of Salafia.The level of amniotic fluid IL-1β, IL-6, IL-8 and TNF-α were analyzed quantitatively by Elisa method. This study showed thet the degree of histologic amnionitis and placentitis, and the level of amniotic fluid's IL-1β, IL-6, IL-8 and TNF-α were significantly higher in pre-term compared to terrn deliveries (p<0.05 and lhere were a positive correlation between the grade of histoLogic inflammation and the level of amniotic fluid's cytokines (Spearmann Rank Conelation test; p<0,05 in cases of preterm labor with intact membrane. The

  13. Analysis of fluid-solid interaction in MHD natural convection in a square cavity equally partitioned by a vertical flexible membrane

    International Nuclear Information System (INIS)

    Mehryan, S.A.M.; Ghalambaz, Mohammad; Ismael, Muneer A.; Chamkha, Ali J.

    2017-01-01

    This paper investigates numerically the problem of unsteady natural convection inside a square cavity partitioned by a flexible impermeable membrane. The finite element method with the arbitrary Lagrangian-Eulerian (ALE) technique has been used to model the interaction of the fluid and the membrane. The horizontal walls of the cavity are kept adiabatic while the vertical walls are kept isothermal at different temperatures. A uniform magnetic field is applied onto the cavity with different orientations. The cavity has been provided by two eyelets to compensate volume changes due the movement of the flexible membrane. A parametric study is carried out for the pertinent parameters, which are the Rayleigh number (10"5–10"8), Hartmann number (0–200) and the orientation of the magnetic field (0–180°). The change in the Hartmann number affects the shape of the membrane and the heat transfer in the cavity. The angle of the magnetic field orientation also significantly affects the shape of the membrane and the heat transfer in the cavity. - Highlights: • Magnetohydrodynamics heat transfer in a partitioned cavity is studied. • There is a flexible membrane in the cavity. • The membrane is modeled using fluid-solid structure interaction. • A moving grid formulation based on ALE is adopted. • The effect of the magnetic field on the natural convection heat transfer is examined.

  14. Analysis of fluid-solid interaction in MHD natural convection in a square cavity equally partitioned by a vertical flexible membrane

    Energy Technology Data Exchange (ETDEWEB)

    Mehryan, S.A.M., E-mail: a.mansuri1366@gmail.com [Department of Mechanical Engineering, Dezful Branch, Islamic Azad University, Dezful (Iran, Islamic Republic of); Ghalambaz, Mohammad, E-mail: m.ghalambaz@iaud.ac.ir [Department of Mechanical Engineering, Dezful Branch, Islamic Azad University, Dezful (Iran, Islamic Republic of); Ismael, Muneer A., E-mail: muneerismael@yahoo.com [Mechanical Engineering Department, Engineering College, University of Basrah, Basrah (Iraq); Chamkha, Ali J., E-mail: achamkha@pmu.edu.sa [Mechanical Engineering Department, Prince Mohammad Bin Fahd University, Al-Khobar 31952 (Saudi Arabia); Prince Sultan Endowment for Energy and Environment, Prince Mohammad Bin Fahd University, Al-Khobar 31952 (Saudi Arabia)

    2017-02-15

    This paper investigates numerically the problem of unsteady natural convection inside a square cavity partitioned by a flexible impermeable membrane. The finite element method with the arbitrary Lagrangian-Eulerian (ALE) technique has been used to model the interaction of the fluid and the membrane. The horizontal walls of the cavity are kept adiabatic while the vertical walls are kept isothermal at different temperatures. A uniform magnetic field is applied onto the cavity with different orientations. The cavity has been provided by two eyelets to compensate volume changes due the movement of the flexible membrane. A parametric study is carried out for the pertinent parameters, which are the Rayleigh number (10{sup 5}–10{sup 8}), Hartmann number (0–200) and the orientation of the magnetic field (0–180°). The change in the Hartmann number affects the shape of the membrane and the heat transfer in the cavity. The angle of the magnetic field orientation also significantly affects the shape of the membrane and the heat transfer in the cavity. - Highlights: • Magnetohydrodynamics heat transfer in a partitioned cavity is studied. • There is a flexible membrane in the cavity. • The membrane is modeled using fluid-solid structure interaction. • A moving grid formulation based on ALE is adopted. • The effect of the magnetic field on the natural convection heat transfer is examined.

  15. Phospholipase A2 activity-dependent and -independent fusogenic activity of Naja nigricollis CMS-9 on zwitterionic and anionic phospholipid vesicles.

    Science.gov (United States)

    Chiou, Yi-Ling; Chen, Ying-Jung; Lin, Shinne-Ren; Chang, Long-Sen

    2011-11-01

    CMS-9, a phospholipase A(2) (PLA(2)) from Naja nigricollis venom, induced the death of human breast cancer MCF-7 cells accompanied with the formation of cell clumps without clear boundaries between cells. Annexin V-FITC staining indicated that abundant phosphatidylserine appeared on the outer membrane of MCF-7 cell clumps, implying the possibility that CMS-9 may promote membrane fusion via anionic phospholipids. To validate this proposition, fusogenic activity of CMS-9 on vesicles composed of zwitterionic phospholipid alone or a combination of zwitterionic and anionic phospholipids was examined. Although CMS-9-induced fusion of zwitterionic phospholipid vesicles depended on PLA(2) activity, CMS-9-induced fusion of vesicles containing anionic phospholipids could occur without the involvement of PLA(2) activity. Membrane-damaging activity of CMS-9 was associated with its fusogenicity. Moreover, CMS-9 induced differently membrane leakage and membrane fusion of vesicles with different compositions. Membrane fluidity and binding capability with phospholipid vesicles were not related to the fusogenicity of CMS-9. However, membrane-bound conformation and mode of CMS-9 depended on phospholipid compositions. Collectively, our data suggest that PLA(2) activity-dependent and -independent fusogenicity of CMS-9 are closely related to its membrane-bound modes and targeted membrane compositions. Copyright © 2011 Elsevier Ltd. All rights reserved.

  16. Binding of Diphtheria Toxin to Phospholipids in Liposomes

    Science.gov (United States)

    Alving, Carl R.; Iglewski, Barbara H.; Urban, Katharine A.; Moss, Joel; Richards, Roberta L.; Sadoff, Jerald C.

    1980-04-01

    Diphtheria toxin bound to the phosphate portion of some, but not all, phospholipids in liposomes. Liposomes consisting of dimyristoyl phosphatidylcholine and cholesterol did not bind toxin. Addition of 20 mol% (compared to dimyristoyl phosphatidylcholine) of dipalmitoyl phosphatidic acid, dicetyl phosphate, phosphatidylinositol phosphate, cardiolipin, or phosphatidylserine in the liposomes resulted in substantial binding of toxin. Inclusion of phosphatidylinositol in dimyristol phosphatidylcholine / cholesterol liposomes did not result in toxin binding. The calcium salt of dipalmitoyl phosphatidic acid was more effective than the sodium salt, and the highest level of binding occurred with liposomes consisting only of dipalmitoyl phosphatidic acid (calcium salt) and cholesterol. Binding of toxin to liposomes was dependent on pH, and the pattern of pH dependence varied with liposomes having different compositions. Incubation of diphtheria toxin with liposomes containing dicetyl phosphate resulted in maximal binding at pH 3.6, whereas binding to liposomes containing phosphatidylinositol phosphate was maximal above pH 7. Toxin did not bind to liposomes containing 20 mol% of a free fatty acid (palmitic acid) or a sulfated lipid (3-sulfogalactosylceramide). Toxin binding to dicetyl phosphate or phosphatidylinositol phosphate was inhibited by UTP, ATP, phosphocholine, or p-nitrophenyl phosphate, but not by uracil. We conclude that (a) diphtheria toxin binds specifically to the phosphate portion of certain phospholipids, (b) binding to phospholipids in liposomes is dependent on pH, but is not due only to electrostatic interaction, and (c) binding may be strongly influenced by the composition of adjacent phospholipids that do not bind toxin. We propose that a minor membrane phospholipid (such as phosphatidylinositol phosphate or phosphatidic acid), or that some other phosphorylated membrane molecule (such as a phosphoprotein) may be important in the initial binding of

  17. 13C- and 15N-Labeling Strategies Combined with Mass Spectrometry Comprehensively Quantify Phospholipid Dynamics in C. elegans.

    Directory of Open Access Journals (Sweden)

    Blair C R Dancy

    Full Text Available Membranes define cellular and organelle boundaries, a function that is critical to all living systems. Like other biomolecules, membrane lipids are dynamically maintained, but current methods are extremely limited for monitoring lipid dynamics in living animals. We developed novel strategies in C. elegans combining 13C and 15N stable isotopes with mass spectrometry to directly quantify the replenishment rates of the individual fatty acids and intact phospholipids of the membrane. Using multiple measurements of phospholipid dynamics, we found that the phospholipid pools are replaced rapidly and at rates nearly double the turnover measured for neutral lipid populations. In fact, our analysis shows that the majority of membrane lipids are replaced each day. Furthermore, we found that stearoyl-CoA desaturases (SCDs, critical enzymes in polyunsaturated fatty acid production, play an unexpected role in influencing the overall rates of membrane maintenance as SCD depletion affected the turnover of nearly all membrane lipids. Additionally, the compromised membrane maintenance as defined by LC-MS/MS with SCD RNAi resulted in active phospholipid remodeling that we predict is critical to alleviate the impact of reduced membrane maintenance in these animals. Not only have these combined methodologies identified new facets of the impact of SCDs on the membrane, but they also have great potential to reveal many undiscovered regulators of phospholipid metabolism.

  18. Phospholipid Complex Technique for Superior Bioavailability of Phytoconstituents

    Directory of Open Access Journals (Sweden)

    Kattamanchi Gnananath

    2017-04-01

    Full Text Available Phytoconstituents have been utilized as medicines for thousands of years, yet their application is limited owing to major hurdles like deficit lipid solubility, large molecular size and degradation in the gastric environment of gut. Recently, phospholipid-complex technique has unveiled in addressing these stumbling blocks either by enhancing the solubilizing capacity or its potentiating ability to pass through the biological membranes and it also protects the active herbal components from degradation. Hence, this phospholipid-complex-technique can enable researchers to deliver the phytoconstituents into systemic circulation by using certain conventional dosage forms like tablets and capsules. This review highlights the unique property of phospholipids in drug delivery, their role as adjuvant in health benefits, and their application in the herbal medicine systems to improve the bioavailability of active herbal components. Also we summarize the prerequisites for phytosomes preparation like the selection of type of phytoconstituents, solvents used, various methods employed in phytosomal preparation and its characterization. Further we discuss the key findings of recent research work conducted on phospholipid-based delivery systems which can enable new directions and advancements to the development of herbal dosage forms.

  19. Atomistic Monte Carlo Simulation of Lipid Membranes

    Directory of Open Access Journals (Sweden)

    Daniel Wüstner

    2014-01-01

    Full Text Available Biological membranes are complex assemblies of many different molecules of which analysis demands a variety of experimental and computational approaches. In this article, we explain challenges and advantages of atomistic Monte Carlo (MC simulation of lipid membranes. We provide an introduction into the various move sets that are implemented in current MC methods for efficient conformational sampling of lipids and other molecules. In the second part, we demonstrate for a concrete example, how an atomistic local-move set can be implemented for MC simulations of phospholipid monomers and bilayer patches. We use our recently devised chain breakage/closure (CBC local move set in the bond-/torsion angle space with the constant-bond-length approximation (CBLA for the phospholipid dipalmitoylphosphatidylcholine (DPPC. We demonstrate rapid conformational equilibration for a single DPPC molecule, as assessed by calculation of molecular energies and entropies. We also show transition from a crystalline-like to a fluid DPPC bilayer by the CBC local-move MC method, as indicated by the electron density profile, head group orientation, area per lipid, and whole-lipid displacements. We discuss the potential of local-move MC methods in combination with molecular dynamics simulations, for example, for studying multi-component lipid membranes containing cholesterol.

  20. Protein kinase C interaction with calcium: a phospholipid-dependent process.

    LENUS (Irish Health Repository)

    Bazzi, M D

    1990-08-21

    The calcium-binding properties of calcium- and phospholipid-dependent protein kinase C (PKC) were investigated by equilibrium dialysis in the presence and the absence of phospholipids. Calcium binding to PKC displayed striking and unexpected behavior; the free proteins bound virtually no calcium at intracellular calcium concentrations and bound limited calcium (about 1 mol\\/mol of PKC) at 200 microM calcium. However, in the presence of membranes containing acidic phospholipids, PKC bound at least eight calcium ions per protein. The presence of 1 microM phorbol dibutyrate (PDBu) in the dialysis buffer had little effect on these calcium-binding properties. Analysis of PKC-calcium binding by gel filtration under equilibrium conditions gave similar results; only membrane-associated PKC bound significant amounts of calcium. Consequently, PKC is a member of what may be a large group of proteins that bind calcium in a phospholipid-dependent manner. The calcium concentrations needed to induce PKC-membrane binding were similar to those needed for calcium binding (about 40 microM calcium at the midpoint). However, the calcium concentration required for PKC-membrane binding was strongly influenced by the phosphatidylserine composition of the membranes. Membranes with higher percentages of phosphatidylserine required lower concentrations of calcium. These properties suggested that the calcium sites may be generated at the interface between PKC and the membrane. Calcium may function as a bridge between PKC and phospholipids. These studies also suggested that calcium-dependent PKC-membrane binding and PKC function could be regulated by a number of factors in addition to calcium levels and diacylglycerol content of the membrane.

  1. Intestinal fluid absorption in anadromous salmonids: importance of tight junctions and aquaporins

    Directory of Open Access Journals (Sweden)

    Kristina eSundell

    2012-09-01

    Full Text Available The anadromous salmonid life cycle includes both fresh water (FW and seawater (SW stages. The parr-smolt transformation (smoltification pre–adapt the fish to SW while still in FW. The osmoregulatory organs change their mode of action from a role of preventing water inflow in FW, to absorb ions to replace water lost by osmosis in SW. During smoltification, the drinking rate increases, in the intestine the ion and fluid transport increases and is further elevated after SW entry. In SW, the intestine absorbs ions to create an inwardly directed water flow which is accomplished by increased Na+,K+-ATPase (NKA activity in the basolateral membrane, driving ion absorption via ion channels and/or co-transporters. This review will aim at discussing the expression patterns of the ion transporting proteins involved in intestinal fluid absorption in the FW stage, during smoltification and after SW entry. Of equal importance for intestinal fluid absorption as the active absorption of ions, is the permeability of the epithelium to ions and water. During the smoltification the increase in NKA activity and water uptake in SW is accompanied by decreased paracellular permeability suggesting a redirection of the fluid movement from a paracellular route in FW, to a transcellular route in SW. Increased transcellular fluid absorption could be achieved by incorporation of aquaporins (AQPs into the enterocyte membranes and/or by a change in fatty acid profile of the enterocyte lipid bilayer. An increased incorporation of unsaturated fatty acids into the membrane phospholipids will increase water permeability by enhancing the fluidity of the membrane. A second aim of the present review is therefore to discuss the presence and regulation of expression of AQPs in the enterocyte membrane as well as to discuss the profile of fatty acids present in the membrane phospholipids during different stages of the salmonid lifecycle.

  2. Phospholipid transfer activities in toad oocytes and developing embryos

    International Nuclear Information System (INIS)

    Rusinol, A.; Salomon, R.A.; Bloj, B.

    1987-01-01

    The role of lipid transfer proteins during plasma membrane biogenesis was explored. Developing amphibia embryos were used because during their growth an active plasma membrane biosynthesis occurs together with negligible mitochondrial and endoplasmic reticulum proliferation. Sonicated vesicles, containing 14 C-labeled phospholipids and 3 H-labeled triolein, as donor particles and cross-linked erythrocyte ghosts as acceptor particles were used to measure phospholipid transfer activities in unfertilized oocytes and in developing embryos of the toad Bufo arenarum. Phosphatidylcholine transfer activity in pH 5.1 supernatant of unfertilized oocytes was 8-fold higher than the activity found in female toad liver supernatant, but dropped steadily after fertilization. After 20 hr of development, at the stage of late blastula, the phosphatidylcholine transfer activity had dropped 4-fold. Unfertilized oocyte supernatant exhibited phosphatidylinositol and phosphatidylethanolamine transfer activity also, but at the late blastula stage the former had dropped 18-fold and the latter was no longer detectable under our assay conditions. Our results show that fertilization does not trigger a phospholipid transport process catalyzed by lipid transfer proteins. Moreover, they imply that 75% of the phosphatidylcholine transfer activity and more than 95% of the phosphatidylinositol and phosphatidylethanolamine transfer activities present in pH 5.1 supernatants of unfertilized oocytes may not be essential for toad embryo development. Our findings do not rule out, however, that a phosphatidylcholine-specific lipid transfer protein could be required for embryo early growth

  3. Interface Fluid Syndrome After Laser In Situ Keratomileusis (LASIK) Because of Fuchs Endothelial Dystrophy Reversed by Descemet Membrane Endothelial Keratoplasty (DMEK).

    Science.gov (United States)

    Luceri, Salvatore; Baksoellah, Zainab; Ilyas, Abbas; Baydoun, Lamis; Melles, Gerrit R J

    2016-12-01

    To describe a case that developed "interface fluid syndrome" after previous laser in situ keratomileusis (LASIK) because of Fuchs endothelial dystrophy (FED), which was reversed by Descemet membrane endothelial keratoplasty (DMEK). A 58-year-old male patient presented with bilateral visual impairment owing to FED and visually significant cataract. Cataract surgery was carried out in both eyes followed by DMEK in his left eye. After cataract surgery, visual acuity did not improve sufficiently because corneal thickness increased and a fine cleft with interface fluid developed between the LASIK-flap and the residual stromal bed. After uneventful DMEK in his left eye, the fluid resolved within a week and visual acuity improved rapidly. This case demonstrates that "interface fluid syndrome" after LASIK caused by concomitant endothelial dysfunction may be reversed by DMEK allowing fast visual recovery.

  4. Women's expectations and experiences of rupture of membranes and views of the potential use of reagent pads for detecting amniotic fluid.

    Science.gov (United States)

    Spiby, Helen; Borrelli, Sara; Hughes, Anita J

    2017-12-01

    To explore first-time mothers' expectations and experiences regarding rupture of membranes at term and their views on the potential use of reagent pads that detect amniotic fluid. There is little information available on women's experiences of spontaneous rupture of membranes, or interest in using methods to confirm rupture of membranes (e.g. reagent pads). Descriptive qualitative study, using focus groups and telephone interviews with women during pregnancy and after the birth of their first baby. Thematic analysis was undertaken to analyse women's responses. Ethics committee approval was obtained. Twenty-five women participated in the study of whom 13 contributed both during pregnancy and postpartum between October 2015-March 2016. Three overarching themes were identified from the data from women's expectations and experiences: uncertainty in how, when and where membranes may rupture; information which was felt to be limited and confirmation of rupture of membranes. The potential use of reagent pads met with varied responses. Women were interested in having facts and figures regarding rupture of membranes, such as characteristics of liquor; volume and probability of membranes rupturing spontaneously at term. Use of a pad as a means of confirmation was viewed as helpful, although the potential for increasing anxiety was raised. © 2017 John Wiley & Sons Ltd.

  5. Nanomechanics of electrospun phospholipid fiber

    Energy Technology Data Exchange (ETDEWEB)

    Mendes, Ana C., E-mail: anac@food.dtu.dk, E-mail: ioach@food.dtu.dk; Chronakis, Ioannis S., E-mail: anac@food.dtu.dk, E-mail: ioach@food.dtu.dk [Technical University of Denmark, DTU-Food, Søltofts Plads B227, DK-2800, Kgs. Lyngby (Denmark); Nikogeorgos, Nikolaos; Lee, Seunghwan [Department of Mechanical Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark)

    2015-06-01

    Electrospun asolectin phospholipid fibers were prepared using isooctane as a solvent and had an average diameter of 6.1 ± 2.7 μm. Their mechanical properties were evaluated by nanoindentation using Atomic Force Microscopy, and their elastic modulus was found to be approximately 17.2 ± 1 MPa. At a cycle of piezo expansion-retraction (loading-unloading) of a silicon tip on a fiber, relatively high adhesion was observed during unloading. It is proposed that this was primarily due to molecular rearrangements at the utmost layers of the fiber caused by the indentation of the hydrophilic tip. The phospholipid fibers were shown to be stable in ambient conditions, preserving the modulus of elasticity up to 24 h.

  6. Nanomechanics of electrospun phospholipid fiber

    DEFF Research Database (Denmark)

    Mendes, Ana Carina Loureiro; Nikogeorgos, Nikolaos; Lee, Seunghwan

    2015-01-01

    Electrospun asolectin phospholipid fibers were prepared using isooctane as a solvent and had an average diameter of 6.1 +/- 2.7 mu m. Their mechanical properties were evaluated by nanoindentation using Atomic Force Microscopy, and their elastic modulus was found to be approximately 17.2 +/- 1MPa....... At a cycle of piezo expansion-retraction (loading-unloading) of a silicon tip on a fiber, relatively high adhesion was observed during unloading. It is proposed that this was primarily due to molecular rearrangements at the utmost layers of the fiber caused by the indentation of the hydrophilic tip....... The phospholipid fibers were shown to be stable in ambient conditions, preserving the modulus of elasticity up to 24 h. (c) 2015 AIP Publishing LLC....

  7. Training affects muscle phospholipid fatty acid composition in humans

    DEFF Research Database (Denmark)

    Helge, Jørn Wulff; Wu, B J; Willer, Mette

    2001-01-01

    on the muscle membrane phospholipid fatty acid composition in humans. Seven male subjects performed endurance training of the knee extensors of one leg for 4 wk. The other leg served as a control. Before, after 4 days, and after 4 wk, muscle biopsies were obtained from the vastus lateralis. After 4 wk......, the phospholipid fatty acid contents of oleic acid 18:1(n-9) and docosahexaenoic acid 22:6(n-3) were significantly higher in the trained (10.9 +/- 0.5% and 3.2 +/- 0.4% of total fatty acids, respectively) than the untrained leg (8.8 +/- 0.5% and 2.6 +/- 0.4%, P fatty acids...... was significantly lower in the trained (11.1 +/- 0.9) than the untrained leg (13.1 +/- 1.2, P fatty acid composition. Citrate synthase activity was increased by 17% in the trained compared with the untrained leg (P

  8. Encapsulation of phytosterols and phytosterol esters in liposomes made with soy phospholipids by high pressure homogenization.

    Science.gov (United States)

    Wang, Fan C; Acevedo, Nuria; Marangoni, Alejandro G

    2017-11-15

    Phytosterols and phytosterol esters were encapsulated within large unilamellar liposomes prepared with soy phospholipids using a microfluidizer. The average particle diameter of these liposomal vesicles increased with increasing amounts of encapsulated phytosterols, especially with increasing free sterol content. The phytosterol content, liposomal particle size, and phytosterol encapsulation efficiency started to plateau when liposomes were prepared with MOPS buffer dispersions that contained 50 mg ml -1 soy phospholipid and more than 4% phytosterol blend, suggesting the saturation of phytosterol encapsulation. We proposed an encapsulation mechanism of free sterols and phytosterol esters in liposomes, where free sterols were mainly encapsulated within the lumen of these liposomes as crystals, and sterol esters and some free sterols were incorporated within the phospholipid bilayer of the liposomal membrane. The results from this work could provide the pharmaceutical and nutraceutical industries a practical method to produce loaded liposomes using inexpensive phospholipid mixtures for the delivery of bioactive ingredients.

  9. Phospholipid metabolism and nuclear function: roles of the lipin family of phosphatidic acid phosphatases.

    Science.gov (United States)

    Siniossoglou, Symeon

    2013-03-01

    Phospholipids play important roles in nuclear function as dynamic building blocks for the biogenesis of the nuclear membrane, as well as signals by which the nucleus communicates with other organelles, and regulate a variety of nuclear events. The mechanisms underlying the nuclear roles of phospholipids remain poorly understood. Lipins represent a family of phosphatidic acid (PA) phosphatases that are conserved from yeasts to humans and perform essential functions in lipid metabolism. Several studies have identified key roles for lipins and their regulators in nuclear envelope organization, gene expression and the maintenance of lipid homeostasis in yeast and metazoans. This review discusses recent advances in understanding the roles of lipins in nuclear structure and function. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. Value of amniotic fluid IL-8 and Annexin A2 in prediction of preterm delivery in preterm labor and preterm premature rupture of membranes.

    Science.gov (United States)

    Jia, Xiaohui

    2014-01-01

    To investigate the clinical significance and value in the prediction of preterm delivery of combined amniotic fluid IL-8 and Annexin A2 levels in preterm premature rupture of membranes (PPROM) and preterm labor (PTL). Sixty pregnant women at < 32 gestational weeks who developed PTL were divided into a PPROM group and a non-PPROM group. Ten normal pregnant women served as a control group. IL-8 and Annexin A2 levels were measured in amniotic fluid samples from each patient. Amniotic fluid IL-8 and Annexin-A2 levels in PTL (PPROM and non-PPROM groups) were significantly higher than those of the controls (p < 0.05). The PPROM group displayed higher amniotic fluid Annexin-A2 levels than did the non-PPROM group, with a statistically significant difference (p < 0.05). The PPROM group showed higher amniotic fluid IL-8 levels than did the non-PPROM group; however, this was statistically insignificant (p = 0.56). Combined detection of amniotic fluid IL-8 and Annexin-A2 in the prediction of preterm delivery within 2 weeks of measurement showed sensitivity of 81.25%, specificity of 88.89% and PPV of 92.86%. Amniotic fluid IL-8 and Annexin-A2 levels are associated with the occurrence of PPROM and PTL. Combined detection of IL-8 and Annexin-A2 levels in identifying preterm delivery within 2 weeks in PTL and PPROM is of possible clinical and predictive value.

  11. Segregated phases in pulmonary surfactant membranes do not show coexistence of lipid populations with differentiated dynamic properties

    DEFF Research Database (Denmark)

    Bernardino de la Serna, Jorge; Orädd, Greger; Bagatolli, Luis

    2009-01-01

    surfactant membranes and membranes reconstituted from two surfactant hydrophobic fractions (i.e., all the lipids plus the hydrophobic proteins SP-B and SP-C, or only the total lipid fraction). These preparations show micrometer-sized fluid ordered/disordered phase coexistence, associated with a broad...... endothermic transition ending close to 37°C. However, both types of membrane exhibit uniform lipid mobility when analyzed by electron paramagnetic resonance with different spin-labeled phospholipids. A similar feature is observed with pulse-field gradient NMR experiments on oriented membranes reconstituted...... from the two types of surfactant hydrophobic extract. These latter results suggest that lipid dynamics are similar in the coexisting fluid phases observed by fluorescence microscopy. Additionally, it is found that surfactant proteins significantly reduce the average intramolecular lipid mobility...

  12. Mechanics, morphology, and mobility in stratum corneum membranes

    Science.gov (United States)

    Olmsted, Peter; Das, Chinmay; Noro, Massimo

    2012-02-01

    The stratum corneum is the outermost layer of skin, and serves as a protective barrier against external agents, and to control moisture. It comprises keratin bodies (corneocytes) embedded in a matrix of lipid bilayers. Unlike the more widely studied phospholipid bilayers, the SC bilayers are typically in a gel-like state. Moreover, the SC membrane composition is radically different from more fluid counterparts: it comprises single tailed fatty acids, ceramides, and cholesterol; with many distinct ceramides possessing different lengths of tails, and always with two tails of different lengths. I will present insight from computer simulations into the morphology, mechanical properties, and diffusion (barrier) properties of these highly heterogeneous membranes. Our results provide some clue as to the design principles for the SC membrane, and is an excellent example of the use of wide polydispersity by natural systems.

  13. INVESTIGATION ON THE MORPHOLOGY AND PROPERTIES OF AGGREGATE STRUCTURES OF NATURAL PHOSPHOLIPIDS IN AQUEOUS SYSTEM USING CRYO-TEM

    Directory of Open Access Journals (Sweden)

    Dwi Hudiyanti

    2012-02-01

    Full Text Available Cryogenic transmission electron microscopy (Cryo-TEM was used to investigate the aggregates morphology and properties of candle tree (Aleurites moluccana endosperm, sesame (Sesamum indicum L. syn. seeds, and coconut (Cocos nucifera endosperm phospholipids in dilute aqueous system. The micrographs showed that candle tree phospholipids formed planar bilayer and cluster of vesicles with lipid droplets, while coconut and sesame phospholipids formed well-defined unilamellar vesicles. The vesicles size could be as small as 50 nm in diameter. Coconut phospholipids also showed a good bending ability. Formation of clusters of vesicles was also found in coconut phospholipids dispersion, but this cluster was easily broken by extrusion through a small pore membrane.

  14. Clinical significance of histologic chorioamnionitis with a negative amniotic fluid culture in patients with preterm labor and premature membrane rupture.

    Directory of Open Access Journals (Sweden)

    Jeong Woo Park

    Full Text Available To evaluate the effect of histological chorioamnionitis (HCA with a negative amniotic fluid (AF culture on adverse pregnancy and neonatal outcomes and inflammatory status in the AF compartment in women with preterm labor or preterm premature rupture of membranes (PPROM.This is a retrospective cohort study of 153 women diagnosed as having a preterm labor or PPROM (20-34 weeks who delivered singleton gestations within 48 hours of amniocentesis. AF obtained through amniocentesis was cultured, and interleukin (IL-6, IL-8, and metalloproteinase-9 (MMP-9 levels were determined. The placentas were examined histologically.The prevalence of HCA with negative AF culture was 23.5% (36/153. The women with HCA but with a negative AF culture (group 2 and those with a positive AF culture (group 3 had a significantly lower mean gestational age at amniocentesis and delivery than those with a negative AF culture and without HCA (group 1. Women in group 3 had the highest levels of AF IL-6, IL-8, and MMP-9, followed by those in group 2, and those in group 1. Composite neonatal morbidity was significantly higher in groups 2 and 3 than in group 1, but this was no longer significant after adjusting for confounders caused mainly by the impact of gestational age.In the women who delivered preterm neonates, HCA with a negative AF culture was associated with increased risks of preterm birth, intense intra-amniotic inflammatory response, and prematurity-associated composite neonatal morbidity, and its risks are similar to the risk posed by positive AF culture.

  15. Transvaginal cervical length and amniotic fluid index: can it predict delivery latency following preterm premature rupture of membranes?

    Science.gov (United States)

    Mehra, Suwan; Amon, Erol; Hopkins, Sarah; Gavard, Jeffrey A; Shyken, Jaye

    2015-03-01

    We sought to determine whether transvaginal cervical length (TVCL), amniotic fluid index (AFI), or a combination of both can predict delivery latency within 7 days in women presenting with preterm premature rupture of membranes (PPROM). This was a prospective observational study of TVCL measurements in 106 singleton pregnancies with PPROM between 23-33 weeks. Delivery latency was defined as the period (in days) from the initial TVCL after PPROM to delivery of the infant, with our primary outcome being delivery within 7 days of TVCL. The independent predictability of significant characteristics for delivery within 7 days was determined using multiple logistic regression. Sensitivity, specificity, and predictive values were used to examine whether the presence of a short TVCL, AFI, or a combination of both affected the risk of delivery within 7 days. Delivery within 7 days occurred in 51/106 (48%) of pregnancies. Median duration (interquartile range) from PPROM to delivery and TVCL to delivery was 8 days (4.0-16.0) and 8 days (3.0-15.0), respectively. Using multiple regression TVCL as a continuous variable (odds ratio, 0.65; 95% confidence interval, 0.44-0.97; P 7 days for TVCL >2 cm alone was 61%. This predictive value changed when analyzed in conjunction with an AFI ≤5 cm and >5 cm at 42% and 89%, respectively. A shorter TVCL and an AFI ≤5 cm independently predict delivery within 7 days in women presenting with PPROM. The combination of an AFI >5 cm and TVCL >2 cm greatly improved the potential to remain undelivered at 7 days following cervical length assessment. These findings may be helpful for counseling and optimizing maternal and neonatal care in women with PPROM. Copyright © 2015 Elsevier Inc. All rights reserved.

  16. Forms, Crosstalks, and the Role of Phospholipid Biosynthesis in Autophagy

    Directory of Open Access Journals (Sweden)

    Leanne Pereira

    2012-01-01

    Full Text Available Autophagy is a highly conserved cellular process occurring during periods of stress to ensure a cell's survival by recycling cytosolic constituents and making products that can be used in energy generation and other essential processes. Three major forms of autophagy exist according to the specific mechanism through which cytoplasmic material is transported to a lysosome. Chaperone-mediated autophagy is a highly selective form of autophagy that delivers specific proteins for lysosomal degradation. Microautophagy is a less selective form of autophagy that occurs through lysosomal membrane invaginations, forming tubes and directly engulfing cytoplasm. Finally, macroautophagy involves formation of new membrane bilayers (autophagosomes that engulf cytosolic material and deliver it to lysosomes. This review provides new insights on the crosstalks between different forms of autophagy and the significance of bilayer-forming phospholipid synthesis in autophagosomal membrane formation.

  17. Tissue phospholipids (TPL) in avian tuberculosis (AT)

    International Nuclear Information System (INIS)

    Nandedkar, A.K.N.; Malhotra, H.C.

    1986-01-01

    AT constitutes one of the major problems in animal husbandry. Chickens (white, leg horn, male, 400-600 g) were infected with Mycobacterium avium maintained on I.U.T. medium to induce clinical AT which was confirmed by histopathological examinations of the affected tissues. Fatty infiltration and tissue enlargement was visible in infected birds. After 4 wks, incorporation of i.v. 32 P (50 uCi/100 g body wt.) in affected tissues was followed for 3,7,9,12 hr intervals. Lipids were extracted and fractionated by silicic acid (SA) column and SA impregnated paper chromatography. When compared with pair-fed controls, in AT slower turnover of TPL in liver, slightly higher in heart and significantly increased turnover of TPL in serum were observed. No appreciable change in total TPL content was noticed in brain, spleen and kidney. Further fractionation of TPL provided better understanding of the metabolism. Increase in lysophosphatidyl-choline (LPC) and -ethanolamine (LPE) content, powerful hemolytic agents, in liver may explain frequent occurrence of anemia in tuberculosis. Also, a concomitant marked increase in the ratio of total saturated/unsaturated fatty acids is observed in serum phosphatidyl choline fraction. This confirms the observation that the membrane phospholipid metabolism is significantly affected in tuberculosis infection

  18. Phospholipid liposomes functionalized by protein

    Science.gov (United States)

    Glukhova, O. E.; Savostyanov, G. V.; Grishina, O. A.

    2015-03-01

    Finding new ways to deliver neurotrophic drugs to the brain in newborns is one of the contemporary problems of medicine and pharmaceutical industry. Modern researches in this field indicate the promising prospects of supramolecular transport systems for targeted drug delivery to the brain which can overcome the blood-brain barrier (BBB). Thus, the solution of this problem is actual not only for medicine, but also for society as a whole because it determines the health of future generations. Phospholipid liposomes due to combination of lipo- and hydrophilic properties are considered as the main future objects in medicine for drug delivery through the BBB as well as increasing their bioavailability and toxicity. Liposomes functionalized by various proteins were used as transport systems for ease of liposomes use. Designing of modification oligosaccharide of liposomes surface is promising in the last decade because it enables the delivery of liposomes to specific receptor of human cells by selecting ligand and it is widely used in pharmacology for the treatment of several diseases. The purpose of this work is creation of a coarse-grained model of bilayer of phospholipid liposomes, functionalized by specific to the structural elements of the BBB proteins, as well as prediction of the most favorable orientation and position of the molecules in the generated complex by methods of molecular docking for the formation of the structure. Investigation of activity of the ligand molecule to protein receptor of human cells by the methods of molecular dynamics was carried out.

  19. Influence of membrane composition on its flexibility

    Energy Technology Data Exchange (ETDEWEB)

    Gerbelli, B.B.; Teixeira da Silva, E.R.; Oliveira, C.L.P.; Oliveira, E.A. [Universidade de Sao Paulo (USP), SP (Brazil)

    2012-07-01

    Full text: Lamellar phases and vesicles composed of lipids have been used as model systems to investigate biological process related to cell membrane as well as promising carriers for drugs and gene therapy. The composition of the membrane determines its three dimensional shape and its properties such as rigidity and compressibility which play an important role on membrane fusion, protein adhesion, interactions between proteins, etc. We present systematic study of a lamellar system composed mainly of lecithin which is a biocompatible phospholipid and simusol, which is a mixture of fatty acids that acts as a cosurfactant introducing flexibility to the membrane. Using X ray scattering we determine the lamellar periodicity as a function of the hydration for different formulations of the membrane; ranging from 100 % to 50 % mass fraction of lecithin. The X-ray spectra are fitted using a 4 Gaussian model [1]that allows us to determine the lamellar periodicity and the Caille parameter [2]. The ideal swelling law relating the membrane volume fraction ({phi}{sub m}) to the lamellar periodicity (D) is given by {phi}{sub m} ={delta}{sub m}/D, where {delta}{sub m} is the thickness membrane, however, when steric interactions are dominant with respect to electrostatic and van der Waals interactions, deviations from this behavior are expected [3]. We present experimental data illustrating the swelling behavior for the membrane compositions and the respective behavior of the hydration limit, membrane Luzzati [4], of the Caille parameter and qualitative interpretation of the interaction forces the systems studying the parameter membrane square amplitude fluctuation[5]. [1] Private communication with Prof. Dr. Cristiano Luis Pinto de Oliveira. [2] Caille A. et all, Acad. Sci. Paris B274 (1972) 891. [3] E. Kurtisovski et all, PRL 98, 258103 (2007). [4] Nagle et all, Curr Opin Struct Biol. 2000 Aug;10(4):474-80. [5] H. I. Petrache. Structure and interactions of fluid phospholipids

  20. Is the fluid mosaic (and the accompanying raft hypothesis a suitable model to describe fundamental features of biological membranes? What may be missing?

    Directory of Open Access Journals (Sweden)

    Luis Alberto Bagatolli

    2013-11-01

    Full Text Available The structure, dynamics, and stability of lipid bilayers are controlled by thermodynamic forces, leading to overall tensionless membranes with a distinct lateral organization and a conspicuous lateral pressure profile. Bilayers are also subject to built-in curvature-stress instabilities that may be released locally or globally in terms of morphological changes leading to the formation of non-lamellar and curved structures. A key controller of the bilayer’s propensity to form curved structures is the average molecular shape of the different lipid molecules. Via the curvature stress, molecular shape mediates a coupling to membrane-protein function and provides a set of physical mechanisms for formation of lipid domains and laterally differentiated regions in the plane of the membrane. Unfortunately, these relevant physical features of membranes are often ignored in the most popular models for biological membranes. Results from a number of experimental and theoretical studies emphasize the significance of these fundamental physical properties and call for a refinement of the fluid mosaic model (and the accompanying raft hypothesis.

  1. Phosphoenolpyruvate carboxylase from C4 leaves is selectively targeted for inhibition by anionic phospholipids

    NARCIS (Netherlands)

    Monreal, J.A.; McLoughlin, F.; Echevarría, C.; García-Mauriño, S.; Testerink, C.

    2010-01-01

    Phosphoenolpyruvate carboxylase (PEPC; EC 4.1.1.31) is an enzyme playing a crucial role in photosynthesis of C4 plants. Here, we identify anionic phospholipids as novel regulators that inhibit C4 PEPC activity and provide evidence that the enzyme partially localizes to membranes.

  2. Controlling the Release of Indomethacin from Glass Solutions Layered with a Rate Controlling Membrane Using Fluid-Bed Processing. Part 1: Surface and Cross-Sectional Chemical Analysis.

    Science.gov (United States)

    Dereymaker, Aswin; Scurr, David J; Steer, Elisabeth D; Roberts, Clive J; Van den Mooter, Guy

    2017-04-03

    Fluid bed coating has been shown to be a suitable manufacturing technique to formulate poorly soluble drugs in glass solutions. Layering inert carriers with a drug-polymer mixture enables these beads to be immediately filled into capsules, thus avoiding additional, potentially destabilizing, downstream processing. In this study, fluid bed coating is proposed for the production of controlled release dosage forms of glass solutions by applying a second, rate controlling membrane on top of the glass solution. Adding a second coating layer adds to the physical and chemical complexity of the drug delivery system, so a thorough understanding of the physical structure and phase behavior of the different coating layers is needed. This study aimed to investigate the surface and cross-sectional characteristics (employing scanning electron microscopy (SEM) and time of flight secondary ion mass spectrometry (ToF-SIMS)) of an indomethacin-polyvinylpyrrolidone (PVP) glass solution, top-coated with a release rate controlling membrane consisting of either ethyl cellulose or Eudragit RL. The implications of the addition of a pore former (PVP) and the coating medium (ethanol or water) were also considered. In addition, polymer miscibility and the phase analysis of the underlying glass solution were investigated. Significant differences in surface and cross-sectional topography of the different rate controlling membranes or the way they are applied (solution vs dispersion) were observed. These observations can be linked to the polymer miscibility differences. The presence of PVP was observed in all rate controlling membranes, even if it is not part of the coating solution. This could be attributed to residual powder presence in the coating chamber. The distribution of PVP among the sample surfaces depends on the concentration and the rate controlling polymer used. Differences can again be linked to polymer miscibility. Finally, it was shown that the underlying glass solution layer

  3. Penetration of the signal sequence of Escherichia coli PhoE protein into phospholipid model membranes leads to lipid-specific changes in signal peptide structure and alterations of lipid organization

    International Nuclear Information System (INIS)

    Batenburg, A.M.; Demel, R.A.; Verkleij, A.J.; de Kruijff, B.

    1988-01-01

    In order to obtain more insight in the initial steps of the process of protein translocation across membranes, biophysical investigations were undertaken on the lipid specificity and structural consequences of penetration of the PhoE signal peptide into lipid model membranes and on the conformation of the signal peptide adopted upon interaction with the lipids. When the monolayer technique and differential scanning calorimetry are used, a stronger penetration is observed for negatively charged lipids, significantly influenced by the physical state of the lipid but not by temperature or acyl chain unsaturation as such. Although the interaction is principally electrostatic, as indicated also by the strong penetration of N-terminal fragments into negatively charged lipid monolayers, the effect of ionic strength suggests an additional hydrophobic component. Most interestingly with regard to the mechanism of protein translocation, the molecular area of the peptide in the monolayer also shows lipid specificity: the area in the presence of PC is consistent with a looped helical orientation, whereas in the presence of cardiolipin a time-dependent conformational change is observed, most likely leading from a looped to a stretched orientation with the N-terminus directed toward the water. This is in line also with the determined peptide-lipid stoichiometry. Preliminary 31 P NMR and electron microscopy data on the interaction with lipid bilayer systems indicate loss of bilayer structure

  4. Oxidative stability of marine phospholipids

    DEFF Research Database (Denmark)

    Lu, Henna Fung Sieng; Nielsen, Nina Skall; Baron, Caroline Pascale

    Many studies have shown that marine phospholipids (MPL) provide more advantages than fish oil. They have better bioavailability, better resistance towards oxidation and higher content of eicosapentaenoic acids (EPA) and docosahexaenoic acids (DHA) than oily triglycerides (fish oil). The objective...... of this study is to investigate the oxidative and hydrolytic stability of MPL. In addition, this study also investigates the effect of chemical composition of MPL and Maillard reaction (interaction between lipids oxidation products with the residue of amino acids) on MPL emulsions’ stability. Firstly, MPL were...... was further investigated through measurement of secondary volatile compounds by Solid Phase Microextraction at several time intervals. On the other hand, the Maillard reaction was investigated through the measurement of color changes and pyrrole content before and after 32 days storage. Preliminary result...

  5. Phospholipid Vesicles in Materials Science

    Energy Technology Data Exchange (ETDEWEB)

    Granick, Steve [Univ. of Illinois, Champaign, IL (United States)

    2016-05-11

    The objective of this research was to develop the science basis needed to deploy phospholipid vesicles as functional materials in energy contexts. Specifically, we sought to: (1) Develop an integrated molecular-level understanding of what determines their dynamical shape, spatial organization, and responsiveness to complex, time-varying environments; and (2) Develop understanding of their active transportation in crowded environments, which our preliminary measurements in cells suggest may hold design principles for targeting improved energy efficiency in new materials systems. The methods to do this largely involved fluorescence imaging and other spectroscopy involving single particles, vesicles, particles, DNA, and endosomes. An unexpected importance outcome was a new method to image light-emitting diodes during actual operation using super-resolution spectroscopy.

  6. Enhanced root growth in phosphate-starved Arabidopsis by stimulating de novo phospholipid biosynthesis through the overexpression of LYSOPHOSPHATIDIC ACID ACYLTRANSFERASE 2 (LPAT2).

    Science.gov (United States)

    Angkawijaya, Artik Elisa; Nguyen, Van Cam; Nakamura, Yuki

    2017-09-01

    Upon phosphate starvation, plants retard shoot growth but promote root development presumably to enhance phosphate assimilation from the ground. Membrane lipid remodelling is a metabolic adaptation that replaces membrane phospholipids by non-phosphorous galactolipids, thereby allowing plants to obtain scarce phosphate yet maintain the membrane structure. However, stoichiometry of this phospholipid-to-galactolipid conversion may not account for the massive demand of membrane lipids that enables active growth of roots under phosphate starvation, thereby suggesting the involvement of de novo phospholipid biosynthesis, which is not represented in the current model. We overexpressed an endoplasmic reticulum-localized lysophosphatidic acid acyltransferase, LPAT2, a key enzyme that catalyses the last step of de novo phospholipid biosynthesis. Two independent LPAT2 overexpression lines showed no visible phenotype under normal conditions but showed increased root length under phosphate starvation, with no effect on phosphate starvation response including marker gene expression, root hair development and anthocyanin accumulation. Accompanying membrane glycerolipid profiling of LPAT2-overexpressing plants revealed an increased content of major phospholipid classes and distinct responses to phosphate starvation between shoot and root. The findings propose a revised model of membrane lipid remodelling, in which de novo phospholipid biosynthesis mediated by LPAT2 contributes significantly to root development under phosphate starvation. © 2017 John Wiley & Sons Ltd.

  7. Mass Spectrometric Determination of the Effect of Surface Deactivation on Membranes Used for In-Situ Sampling of Cerebrospinal Fluid (CSF

    Directory of Open Access Journals (Sweden)

    Torgny Undin

    2018-05-01

    Full Text Available In this paper, a strategy for structured monitoring of surface modifications to control protein adsorption to membrane structures is presented. The already established on-surface enzymatic digestion (oSED method combined with nano-liquid chromatography and tandem mass spectrometry (LC-MS/MS analysis was employed for the analysis of proteins in ventricular cerebrospinal fluid (vCSF from neurointensive care patients. Protein adsorption was studied by in-situ sampling in a temporally resolved manner on both immobilized native and Pluronic-deactivated membranes. Deactivation was significantly reducing the protein adsorption but it also induced novel selective properties of the surface. The proposed versatile strategy will facilitate protein-biomaterial, protein-polymer, protein-protein interaction studies in the future.

  8. The Synovial Lining and Synovial Fluid Properties after Joint Arthroplasty

    Directory of Open Access Journals (Sweden)

    Michael Shang Kung

    2015-05-01

    Full Text Available The lubrication of the cartilaginous structures in human joints is provided by a fluid from a specialized layer of cells at the surface of a delicate tissue called the synovial lining. Little is known about the characteristics of the fluids produced after a joint arthroplasty procedure. A literature review was carried out to identify papers that characterized the synovial lining and the synovial fluids formed after total hip or knee arthroplasty. Five papers about synovial lining histology and six papers about the lubricating properties of the fluids were identified. The cells making up the re-formed synovial lining, as well as the lining of interface membranes, were similar to the typical Type A and B synoviocytes of normal joints. The synovial fluids around joint replacement devices were typically lower in viscosity than pre-arthroplasty fluids but the protein concentration and phospholipid concentrations tended to be comparable, suggesting that the lining tissue function was preserved after arthroplasty. The widespread, long-term success of joint arthroplasty suggests that the lubricant formed from implanted joint synovium is adequate for good clinical performance in the majority of joints. The role the fluid plays in component wear or failure is a topic for future study.

  9. Pollen viability and membrane lipid composition

    NARCIS (Netherlands)

    Bilsen, van D.G.J.L.

    1993-01-01

    In this thesis membrane lipid composition is studied in relation to pollen viability during storage. Chapter 1 reviews pollen viability, membranes in the dry state and membrane changes associated with cellular aging. This chapter is followed by a study of age-related changes in phospholipid

  10. ER phospholipid composition modulates lipogenesis during feeding and in obesity.

    Science.gov (United States)

    Rong, Xin; Wang, Bo; Palladino, Elisa Nd; de Aguiar Vallim, Thomas Q; Ford, David A; Tontonoz, Peter

    2017-10-02

    Sterol regulatory element-binding protein 1c (SREBP-1c) is a central regulator of lipogenesis whose activity is controlled by proteolytic cleavage. The metabolic factors that affect its processing are incompletely understood. Here, we show that dynamic changes in the acyl chain composition of ER phospholipids affect SREBP-1c maturation in physiology and disease. The abundance of polyunsaturated phosphatidylcholine in liver ER is selectively increased in response to feeding and in the setting of obesity-linked insulin resistance. Exogenous delivery of polyunsaturated phosphatidylcholine to ER accelerated SREBP-1c processing through a mechanism that required an intact SREBP cleavage-activating protein (SCAP) pathway. Furthermore, induction of the phospholipid-remodeling enzyme LPCAT3 in response to liver X receptor (LXR) activation promoted SREBP-1c processing by driving the incorporation of polyunsaturated fatty acids into ER. Conversely, LPCAT3 deficiency increased membrane saturation, reduced nuclear SREBP-1c abundance, and blunted the lipogenic response to feeding, LXR agonist treatment, or obesity-linked insulin resistance. Desaturation of the ER membrane may serve as an auxiliary signal of the fed state that promotes lipid synthesis in response to nutrient availability.

  11. Packing of ganglioside-phospholipid monolayers

    DEFF Research Database (Denmark)

    Majewski, J.; Kuhl, T.L.; Kjær, K.

    2001-01-01

    Using synchrotron grazing-incidence x-ray diffraction (GIXD) and reflectivity, the in-plane and out-of-plane structure of mixed ganglioside-phospholipid monolayers was investigated at the air-water interface. Mixed monolayers of 0, 5, 10, 20, and 100 mol% ganglioside GM, and the phospholipid...... monolayers did not affect hydrocarbon tail packing (fluidization or condensation of the hydrocarbon region). This is in contrast to previous investigations of lipopolymer-lipid mixtures, where the packing structure of phospholipid monolayers was greatly altered by the inclusion of lipids bearing hydrophilic...

  12. The herpes simplex virus 1 U{sub S}3 regulates phospholipid synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Wild, Peter, E-mail: pewild@access.uzh.ch [Institute of Veterinary Anatomy, University of Zuerich (Switzerland); Institute of Virology, University of Zuerich (Switzerland); Oliveira, Anna Paula de [Institute of Virology, University of Zuerich (Switzerland); Sonda, Sabrina [Institute for Parasitology, University of Zuerich (Switzerland); Schraner, Elisabeth M. [Institute of Veterinary Anatomy, University of Zuerich (Switzerland); Institute of Virology, University of Zuerich (Switzerland); Ackermann, Mathias; Tobler, Kurt [Institute of Virology, University of Zuerich (Switzerland)

    2012-10-25

    Herpes simplex virus type 1 capsids bud at nuclear and Golgi membranes for envelopment by phospholipid bilayers. In the absence of U{sub S}3, nuclear membranes form multiple folds harboring virions that suggests disturbance in membrane turnover. Therefore, we investigated phospholipid metabolism in cells infected with the U{sub S}3 deletion mutant R7041({Delta}U{sub S}3), and quantified membranes involved in viral envelopment. We report that (i) [{sup 3}H]-choline incorporation into nuclear membranes and cytoplasmic membranes was enhanced peaking at 12 or 20 h post inoculation with wild type HSV-1 and R7041({Delta}U{sub S}3), respectively, (ii) the surface area of nuclear membranes increased until 24 h of R7041({Delta}U{sub S}3) infection forming folds that equaled {approx}45% of the nuclear surface, (iii) the surface area of viral envelopes between nuclear membranes equaled {approx}2400 R7041({Delta}U{sub S}3) virions per cell, and (iv) during R7041({Delta}U{sub S}3) infection, the Golgi complex expanded dramatically. The data indicate that U{sub S}3 plays a significant role in regulation of membrane biosynthesis.

  13. Phosphatidic acid is a major phospholipid class in reproductive organs of Arabidopsis thaliana.

    Science.gov (United States)

    Yunus, Ian Sofian; Cazenave-Gassiot, Amaury; Liu, Yu-Chi; Lin, Ying-Chen; Wenk, Markus R; Nakamura, Yuki

    2015-01-01

    Phospholipids are the crucial components of biological membranes and signal transduction. Among different tissues, flower phospholipids are one of the least characterized features of plant lipidome. Here, we report that floral reproductive organs of Arabidopsis thaliana contain high levels of phosphatidic acid (PA), a known lipid second messenger. By using floral homeotic mutants enriched with specific floral organs, lipidomics study showed increased levels of PA species in ap3-3 mutant with enriched pistils. Accompanied gene expression study for 7 diacylglycerol kinases and 11 PA phosphatases revealed distinct floral organ specificity, suggesting an active phosphorylation/dephosphorylation between PA and diacylglycerol in flowers. Our results suggest that PA is a major phospholipid class in floral reproductive organs of A. thaliana.

  14. Effect of intra-membrane C60 fullerenes on the modulus of elasticity and the mechanical resistance of gel and fluid lipid bilayers

    Science.gov (United States)

    Zhou, Jihan; Liang, Dehai; Contera, Sonia

    2015-10-01

    Penetration and partition of C60 to the lipid bilayer core are both relevant to C60 toxicity, and useful to realise C60 biomedical potential. A key aspect is the effect of C60 on bilayer mechanical properties. Here, we present an experimental study on the mechanical effect of the incorporation of C60 into the hydrophobic core of fluid and gel phase zwitterionic phosphatidylcholine (PC) lipid bilayers. We demonstrate its incorporation inside the hydrophobic lipid core and the effect on the packing of the lipids and the vesicle size using a combination of infrared (IR) spectroscopy, atomic force microscopy (AFM) and laser light scattering. Using AFM we measured the Young's modulus of elasticity (E) of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) in the absence (presence) of intra-membranous C60 at 24.5 °C. E of fluid phase supported bilayers is not altered by C60, but E increases with incorporation of C60 in gel phase bilayers. The increase is higher for longer hydrocarbon chains: 1.6 times for DPPC and 2 times for DSPC. However the mechanical resistance of gel phase bilayers of curved bilayered structures decreases with the incorporation of C60. Our combined results indicate that C60 causes a decrease in gel phase lipid mobility, i.e. an increase in membrane viscosity.

  15. Process to remove turbidity-causing components from a fluid by micro-filtration - passes the fluid across an asymmetric membrane with inlet pores larger than those of nominal size, and cleans the membrane by backwashing

    DEFF Research Database (Denmark)

    1995-01-01

    turbidity-causing components from beer, wine, fruit juice, milk and blood, and from bacterial and enzyme suspensions. ADVANTAGE-The process greatly reduces the lost production time associated with earlier filtration methods, and beneficial components can pass through the membrane, thereby improving...

  16. The interaction of insulin with phospholipids

    Science.gov (United States)

    Perry, M. C.; Tampion, W.; Lucy, J. A.

    1971-01-01

    1. A simple two-phase chloroform–aqueous buffer system was used to investigate the interaction of insulin with phospholipids and other amphipathic substances. 2. The distribution of 125I-labelled insulin in this system was determined after incubation at 37°C. Phosphatidic acid, dicetylphosphoric acid and, to a lesser extent, phosphatidylcholine and cetyltrimethylammonium bromide solubilized 125I-labelled insulin in the chloroform phase, indicating the formation of chloroform-soluble insulin–phospholipid or insulin–amphipath complexes. Phosphatidylethanolamine, sphingomyelin, cholesterol, stearylamine and Triton X-100 were without effect. 3. Formation of insulin–phospholipid complex was confirmed by paper chromatography. 4. The two-phase system was adapted to act as a simple functional system with which to investigate possible effects of insulin on the structural and functional properties of phospholipid micelles in chloroform, by using the distribution of [14C]glucose between the two phases as a monitor of phospholipid–insulin interactions. The ability of phospholipids to solubilize [14C]glucose in chloroform increased in the order phosphatidylcholineInsulin decreased the [14C]glucose solubilized by phosphatidylcholine, phosphatidylethanolamine and phosphatidic acid, but not by sphingomyelin. 5. The significance of these results and the molecular requirements for the formation of insulin–phospholipid complexes in chloroform are discussed. PMID:5158903

  17. Salicylic acid induces vanillin synthesis through the phospholipid signaling pathway in Capsicum chinense cell cultures.

    Science.gov (United States)

    Rodas-Junco, Beatriz A; Cab-Guillén, Yahaira; Muñoz-Sánchez, J Armando; Vázquez-Flota, Felipe; Monforte-González, Miriam; Hernández-Sotomayor, S M Teresa

    2013-10-01

    Signal transduction via phospholipids is mediated by phospholipases such as phospholipase C (PLC) and D (PLD), which catalyze hydrolysis of plasma membrane structural phospholipids. Phospholipid signaling is also involved in plant responses to phytohormones such as salicylic acid (SA). The relationships between phospholipid signaling, SA, and secondary metabolism are not fully understood. Using a Capsicum chinense cell suspension as a model, we evaluated whether phospholipid signaling modulates SA-induced vanillin production through the activation of phenylalanine ammonia lyase (PAL), a key enzyme in the biosynthetic pathway. Salicylic acid was found to elicit PAL activity and consequently vanillin production, which was diminished or reversed upon exposure to the phosphoinositide-phospholipase C (PI-PLC) signaling inhibitors neomycin and U73122. Exposure to the phosphatidic acid inhibitor 1-butanol altered PLD activity and prevented SA-induced vanillin production. Our results suggest that PLC and PLD-generated secondary messengers may be modulating SA-induced vanillin production through the activation of key biosynthetic pathway enzymes.

  18. Intermolecular crosslinks mediate aggregation of phospholipid vesicles by pulmonary surfactant-associated protein SAP-35

    International Nuclear Information System (INIS)

    Ross, G.R.; Sawyer, J.; Whitsett, J.

    1987-01-01

    Pulmonary surfactant-associated protein, Mr=35,000 (SAP-35) is known to bind phospholipids and is hypothesized to function in the organization of surfactant lipid membranes. SAP-35 has been observed to accelerate the calcium-induced aggregation of phospholipid vesicles. In order to define the molecular domains of SAP-35 which function in phospholipid aggregation, they have measured the light scattering properties (400nm) of purified canine SAP-35-phospholipid vesicle suspensions. Accelerated aggregation of unilamellar vesicles, requires SAP-35 and at least 2mM free calcium. The initial rate of A 400 change is proportional to the amount of native SAP-35 added over lipid:protein molar ratios ranging from 100:1 to 5000:1. Removal of the SAP-35 collagen-like domain and a specific cysteine residue involved in intermolecular disulfide bonding by bacterial collagenase digestion destroys the protein's lipid aggregation activity. Pre-incubation of SAP-35 with dithiothreitol (DTT) under nondenaturing conditions also results in a time-dependent loss of aggregation activity. Sucrose density gradient floatation of SAP-35 with 14 C dipalmitoyl phosphatidycholine labelled vesicles in the absence or presence of DTT suggests retention of SAP-35 lipid binding capacity. These data demonstrate the importance of SAP-35 triple helix and disulfide crosslinking integrity for the aggregation of unilamellar phospholipid vesicles

  19. Anomalous Behavior of Hyaluronan Crosslinking Due to the Presence of Excess Phospholipids in the Articular Cartilage System of Osteoarthritis

    Directory of Open Access Journals (Sweden)

    Piotr Bełdowski

    2017-12-01

    Full Text Available Lubrication of articular cartilage is a complex multiscale phenomenon in synovial joint organ systems. In these systems, synovial fluid properties result from synergistic interactions between a variety of molecular constituent. Two molecular classes in particular are of importance in understanding lubrication mechanisms: hyaluronic acid and phospholipids. The purpose of this study is to evaluate interactions between hyaluronic acid and phospholipids at various functionality levels during normal and pathological synovial fluid conditions. Molecular dynamic simulations of hyaluronic acid and phospholipids complexes were performed with the concentration of hyaluronic acid set at a constant value for two organizational forms, extended (normal and coiled (pathologic. The results demonstrated that phospholipids affect the crosslinking mechanisms of hyaluronic acid significantly and the influence is higher during pathological conditions. During normal conditions, hyaluronic acid and phospholipid interactions seem to have no competing mechanism to that of the interaction between hyaluronic acid to hyaluronic acid. On the other hand, the structures formed under pathologic conditions were highly affected by phospholipid concentration.

  20. Rapid and simple pretreatment of human body fluids using electromembrane extraction across supported liquid membrane for capillary electrophoretic determination of lithium.

    Science.gov (United States)

    Strieglerová, Lenka; Kubáň, Pavel; Boček, Petr

    2011-05-01

    Electromembrane extraction was used for simultaneous sample cleanup and preconcentration of lithium from untreated human body fluids. The sample of a body fluid was diluted 100 times with 0.5 mM Tris solution and lithium was extracted by electromigration through a supported liquid membrane composed of 1-octanol into 100 mM acetic acid acceptor solution. Matrix compounds, such as proteins, red blood cells, and other high-molecular-weight compounds were efficiently retained on the supported liquid membrane. The liquid membrane was anchored in pores of a short segment of a polypropylene hollow fiber, which represented a low cost, single use, disposable extraction unit and was discarded after each use. Acceptor solutions were analyzed using capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C(4) D) and baseline separation of lithium was achieved in a background electrolyte solution consisting of 18 mM L-histidine and 40 mM acetic acid at pH 4.6. Repeatability of the electromembrane extraction-CE-C(4) D method was evaluated for the determination of lithium in standard solutions and real samples and was better than 0.6 and 8.2% for migration times and peak areas, respectively. The concentration limit of detection of 9 nM was achieved. The developed method was applied to the determination of lithium in urine, blood serum, blood plasma, and whole blood at both endogenous and therapeutic concentration levels. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Modulation of amniotic fluid activin-a and inhibin-a in women with preterm premature rupture of the membranes and infection-induced preterm birth.

    Science.gov (United States)

    Rosenberg, Victor A; Buhimschi, Irina A; Dulay, Antonette T; Abdel-Razeq, Sonya S; Oliver, Emily A; Duzyj, Christina M; Lipkind, Heather; Pettker, Christian M; Buhimschi, Catalin S

    2012-02-01

    Activins and inhibins are important modulators of inflammatory processes. We explored activation of amniotic fluid (AF) activin-A and inhibin-A system in women with intra-amniotic infection and preterm premature rupture of the membranes (PPROM). We analyzed 78 AF samples: '2nd trimester-control' (n=12), '3rd trimester-control' (n=14), preterm labor with intact membranes [positive-AF-cultures (n=13), negative-AF-cultures (n=13)], and PPROM [positive-AF-cultures (n=13), negative-AF-cultures (n=13)]. Activin-A levels were evaluated ex-vivo following incubation of amniochorion and placental villous explants with Gram-negative lipopolysaccharide (LPS) or Gram-positive (Pam3Cys) bacterial mimics. Ability of recombinant activin-A and inhibin-A to modulate inflammatory reactions in fetal membranes was explored through explants' IL-8 release. Activin-A and inhibin-A were present in human AF and were gestational age-regulated. Activin-A was significantly upregulated by infection. Lower inhibin-A levels were seen in PPROM. LPS elicited release of activin-A from amniochorion, but not from villous explants. Recombinant activin-A stimulated IL-8 release from amniochorion, an effect that was not reversed by inhibin-A. Human AF activin-A and inhibin-A are involved in biological processes linked to intra-amniotic infection/inflammation-induced preterm birth. © 2011 John Wiley & Sons A/S.

  2. Impacts of Natural Surfactant Soybean Phospholipid on Wettability of High-rank Coal Reservoir

    Science.gov (United States)

    Lyu, S.; Xiao, Y.; Yuan, M.; Wang, S.

    2017-12-01

    It is significant to change the surface wettability of coal rock with the surfactant in coal mining and coalbed methane exploitation. Soybean phospholipid (SP) is a kind of natural zwitterionic surfactant which is non-toxic and degradable. In order to study the effects of soybean phospholipid on wettability of high-rank coal in Qinshui Basin, some experiments including surface tension test, contact angle measurement on the coal surface, coal fines imbibition, observation of dispersion effect and gas permeability test were carried out, and water locking mechanism of fracturing fluid in micro fractures of coal reservoir was analyzed. The results show that the surface of high-rank coal was negatively charged in solution and of weak hydrophilicity. The soybean phospholipid with the mass fraction of 0.1% reduced the surface tension of water by 69%, and increased the wettability of coal. Meanwhile, the soybean phospholipid helped coal fines to disperse by observation of the filter cake with the scanning electron microscope. The rising rate of soybean phospholipid solution in the pipe filled with coal fines was lower than that of anionic and cationic surfactant, higher than that of clean water and non-ionic surfactant. Composite surfactant made up of soybean phospholipid and OP-10 at the ratio of 1:3 having a low surface tension and large contact angle, reduced the capillary force effectively, which could be conducive to discharge of fracturing fluid from coal reservoir micro fracture and improve the migration channels of gas. Therefore it has a broad application prospect.

  3. Phospholipid transfer from vesicles to high density lipoproteins, catalyzed by human plasma phospholipid transfer protein

    International Nuclear Information System (INIS)

    Sweeny, S.A.

    1985-01-01

    Human plasma phospholipid transfer protein (PLTP) catalyzes the mass transfer of phosphatidylcholine (PC). Partial purification of PLTP yielded proteins with apparent M/sub r/ = 59,000 and 40,000 by SDS-PAGE. PLTP activity was measured by transfer of [ 14 C]L-α-dipalmitoyl PC from egg-PC vesicles to HDL. Activity was enhanced at low pH (4.5) upon addition of β-mercaptoethanol while Ca +2 and Na + had no effect. E/sub act/ for facilitated PC transfer was 18.2 +/- 2 kcal/mol. The donor specificity of PLTP was examined using vesicles containing egg-PC plus cholesterol or sphingomyelin. The fluidity of the donor membrane (measured by fluorescence polarization of diphenylhexatriene) correlated strongly with a decrease in PLTP activity. Phosphatidic acid did not affect activity. Increase in vesicle size reduced activity. The acceptor specificity of PLTP was examined using chemically modified HDL. PLTP activity increased up to 1.7-fold with an initial increase in negative charge and then decreased upon extensive modification. A mechanism is proposed where PLTP binds to vesicls and enhances the diffusion of PC into the medium where it is adsorbed by HDL

  4. Non-invasively collected amniotic fluid as a source of possible biomarkers for premature rupture of membranes investigated by proteomic approach.

    Science.gov (United States)

    Consonni, Sara; Mainini, Veronica; Pizzardi, Agnese; Gianazza, Erica; Chinello, Clizia; Locatelli, Anna; Magni, Fulvio

    2014-02-01

    Preterm delivery is one of the main causes of perinatal morbidity and mortality and it accounts for 75 % of perinatal mortality and more than half of the long-term morbidity. We applied a proteomic approach based on mass spectrometry (MS) for biomarkers discovery of preterm premature rupture of membranes (pPROM) by investigating amniotic fluid (AF) invasively and non-invasively collected. Amniotic fluid was obtained from vagina of women with pPROM (group 1), PROM at term (group 2) and by genetic amniocentesis (group 3). Pre-fractionated AF proteome was analyzed through matrix assisted laser desorption ionization-time of flight (MALDI-TOF) MS. The characterization of proteins/peptides of interest was obtained by high performance liquid chromatography-electrospray tandem MS. Three peptides overexpressed in pPROM and able to discriminate the groups 1 and 2 were detected. One peptide was identified as the fragment Gly452LAVPDGPLGLPPKPro466 of the protein KIAA1522, expressed by fetal brain and liver. This peptide was overexpressed in a patient of the group 3, completely asymptomatic at the time of the amniocentesis, who later developed pPROM. Amniotic fluid invasively and non-invasively collected can be analyzed by MALDI-TOF MS to obtain proteomic profiles. Proteomic analysis identified a peptide with promising diagnostic capability for pPROM.

  5. Cholesterol rules: direct observation of the coexistence of two fluid phases in native pulmonary surfactant membranes at physiological temperatures

    DEFF Research Database (Denmark)

    Bernardino de la Serna, Jorge; Perez-Gil, Jesus; Simonsen, Adam C

    2004-01-01

    part in the surfactant structures could be organized heterogeneously in the form of inplane domains, originating from particular distributions of specific proteins and lipids. Here we report novel results concerning the lateral organization of bilayer membranes made of native pulmonary surfactant where...

  6. In-situ assessment of biofilm formation in submerged membrane system using optical coherence tomography and computational fluid dynamics

    KAUST Repository

    Fortunato, Luca; Qamar, Adnan; Wang, Yiran; Jeong, Sanghyun; Leiknes, TorOve

    2016-01-01

    coherence tomography (OCT), allowing the in-situ investigation of the biofilm structure for 43 d. The OCT enabled to obtain a time-lapse of biofilm development on the membrane under the continuous operation. Acquired real-time information on the biofilm

  7. Transfer of oleic acid between albumin and phospholipid vesicles

    International Nuclear Information System (INIS)

    Hamilton, J.A.; Cistola, D.P.

    1986-01-01

    The net transfer of oleic acid between egg phosphatidylcholine unilamellar vesicles and bovine serum albumin has been monitored by 13 C NMR spectroscopy and 90% isotopically substituted [1- 13 C]oleic acid. The carboxyl chemical shifts of oleic acid bound to albumin were different from those for oleic acid in phospholipid vesicles. Therefore, in mixtures of donor particles, the equilibrium distribution of oleic acid was determined from chemical shift and peak intensity data without separation of donor and acceptor particles. In a system containing equal masses of albumin and phospholipid and a stoichiometry of 4-5 mol of oleic acid per mol of albumin, the oleic acid distribution was pH dependent, with ≥80% of the oleic acid associated with albumin at pH 7.4; association was ≥90% at pH 8.0. Decreasing the pH below 7.4 markedly decreased the proportion of fatty acid bound to albumin. The distribution was reversible with pH and was independent of whether vesicles or albumin acted as a donor. These data suggest that pH may strongly influence the partitioning of fatty acid between cellular membranes and albumin. The 13 C NMR method is also advantageous because it provides information about the structural environments of oleic acid bound to albumin or phospholipid, the ionization state of oleic acid in each environment, and the structural integrity of the vesicles. In addition, minimum and maximum limits for the exchange rates of oleic acid among different environments were obtained from the NMR data

  8. Visualization and analysis of lipopolysaccharide distribution in binary phospholipid bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Henning, Maria Florencia [Instituto de Investigaciones Bioquimicas La Plata (INIBIOLP), CCT-La Plata, CONICET, Facultad de Ciencias Medicas, UNLP, Calles 60 y 120, 1900 La Plata (Argentina); Sanchez, Susana [Laboratory for Fluorescence Dynamics, University of California-Irvine, Irvine, CA (United States); Bakas, Laura, E-mail: lbakas@biol.unlp.edu.ar [Instituto de Investigaciones Bioquimicas La Plata (INIBIOLP), CCT-La Plata, CONICET, Facultad de Ciencias Medicas, UNLP, Calles 60 y 120, 1900 La Plata (Argentina); Departamento de Ciencias Biologicas, Facultad de Ciencias Exactas, UNLP, Calles 47 y 115, 1900 La Plata (Argentina)

    2009-05-22

    Lipopolysaccharide (LPS) is an endotoxin released from the outer membrane of Gram-negative bacteria during infections. It have been reported that LPS may play a role in the outer membrane of bacteria similar to that of cholesterol in eukaryotic plasma membranes. In this article we compare the effect of introducing LPS or cholesterol in liposomes made of dipalmitoylphosphatidylcholine/dioleoylphosphatidylcholine on the solubilization process by Triton X-100. The results show that liposomes containing LPS or cholesterol are more resistant to solubilization by Triton X-100 than the binary phospholipid mixtures at 4 {sup o}C. The LPS distribution was analyzed on GUVs of DPPC:DOPC using FITC-LPS. Solid and liquid-crystalline domains were visualized labeling the GUVs with LAURDAN and GP images were acquired using a two-photon microscope. The images show a selective distribution of LPS in gel domains. Our results support the hypothesis that LPS could aggregate and concentrate selectively in biological membranes providing a mechanism to bring together several components of the LPS-sensing machinery.

  9. Premature rupture of membranes

    Science.gov (United States)

    ... gov/ency/patientinstructions/000512.htm Premature rupture of membranes To use the sharing features on this page, ... water that surrounds your baby in the womb. Membranes or layers of tissue hold in this fluid. ...

  10. Metformin Decouples Phospholipid Metabolism in Breast Cancer Cells.

    Directory of Open Access Journals (Sweden)

    Tim A D Smith

    Full Text Available The antidiabetic drug metformin, currently undergoing trials for cancer treatment, modulates lipid and glucose metabolism both crucial in phospholipid synthesis. Here the effect of treatment of breast tumour cells with metformin on phosphatidylcholine (PtdCho metabolism which plays a key role in membrane synthesis and intracellular signalling has been examined.MDA-MB-468, BT474 and SKBr3 breast cancer cell lines were treated with metformin and [3H-methyl]choline and [14C(U]glucose incorporation and lipid accumulation determined in the presence and absence of lipase inhibitors. Activities of choline kinase (CK, CTP:phosphocholine cytidylyl transferase (CCT and PtdCho-phospholipase C (PLC were also measured. [3H] Radiolabelled metabolites were determined using thin layer chromatography.Metformin-treated cells exhibited decreased formation of [3H]phosphocholine but increased accumulation of [3H]choline by PtdCho. CK and PLC activities were decreased and CCT activity increased by metformin-treatment. [14C] incorporation into fatty acids was decreased and into glycerol was increased in breast cancer cells treated with metformin incubated with [14C(U]glucose.This is the first study to show that treatment of breast cancer cells with metformin induces profound changes in phospholipid metabolism.

  11. Molecular dynamics study of lipid bilayers modeling the plasma membranes of normal murine thymocytes and leukemic GRSL cells.

    Science.gov (United States)

    Andoh, Yoshimichi; Okazaki, Susumu; Ueoka, Ryuichi

    2013-04-01

    Molecular dynamics (MD) calculations for the plasma membranes of normal murine thymocytes and thymus-derived leukemic GRSL cells in water have been performed under physiological isothermal-isobaric conditions (310.15K and 1 atm) to investigate changes in membrane properties induced by canceration. The model membranes used in our calculations for normal and leukemic thymocytes comprised 23 and 25 kinds of lipids, respectively, including phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol, sphingomyelin, lysophospholipids, and cholesterol. The mole fractions of the lipids adopted here were based on previously published experimental values. Our calculations clearly showed that the membrane area was increased in leukemic cells, and that the isothermal area compressibility of the leukemic plasma membranes was double that of normal cells. The calculated membranes of leukemic cells were thus considerably bulkier and softer in the lateral direction compared with those of normal cells. The tilt angle of the cholesterol and the conformation of the phospholipid fatty acid tails both showed a lower level of order in leukemic cell membranes compared with normal cell membranes. The lateral radial distribution function of the lipids also showed a more disordered structure in leukemic cell membranes than in normal cell membranes. These observations all show that, for the present thymocytes, the lateral structure of the membrane is considerably disordered by canceration. Furthermore, the calculated lateral self-diffusion coefficient of the lipid molecules in leukemic cell membranes was almost double that in normal cell membranes. The calculated rotational and wobbling autocorrelation functions also indicated that the molecular motion of the lipids was enhanced in leukemic cell membranes. Thus, here we have demonstrated that the membranes of thymocyte leukemic cells are more disordered and more fluid than normal cell membranes. Copyright © 2013

  12. A COMPUTATIONAL FLUID DYNAMICS ANALYSIS OF AIR FLOW THROUGH A TELECOM BACK-UP UNIT POWERED BY AN AIR-COOLED PROTON EXCHANGE MEMBRANE FUEL CELL

    DEFF Research Database (Denmark)

    Gao, Xin; Berning, Torsten; Kær, Søren Knudsen

    2016-01-01

    Proton exchange membrane fuel cells (PEMFC’s) are currently being commercialized for various applications ranging from automotive to stationary such as powering telecom back-up units. In PEMFC’s, oxygen from air is internally combined with hydrogen to form water and produce electricity and heat....... This product heat has to be effectively removed from the fuel cell, and while automotive fuel cells are usually liquid-cooled using a secondary coolant loop similar to the internal combustion engines, stationary fuel cell systems as they are used for telecom back-up applications often rely on excessive air fed...... to the fuel cell cathode to remove the heat. Thereby, the fuel cell system is much simpler and cheaper while the fuel cell performance is substantially lower compared to automotive fuel cells. This work presents a computational fluid dynamics analysis on the heat management of an air-cooled fuel cell powered...

  13. Specific Interaction between Redox Phospholipid Polymers and Plastoquinone in Photosynthetic Electron Transport Chain.

    Science.gov (United States)

    Tanaka, Kenya; Kaneko, Masahiro; Ishikawa, Masahito; Kato, Souichiro; Ito, Hidehiro; Kamachi, Toshiaki; Kamiya, Kazuhide; Nakanishi, Shuji

    2017-04-19

    Redox phospholipid polymers added in culture media are known to be capable of extracting electrons from living photosynthetic cells across bacterial cell membranes with high cytocompatibility. In the present study, we identify the intracellular redox species that transfers electrons to the polymers. The open-circuit electrochemical potential of an electrolyte containing the redox polymer and extracted thylakoid membranes shift to positive (or negative) under light irradiation, when an electron transport inhibitor specific to plastoquinone is added upstream (or downstream) in the photosynthetic electron transport chain. The same trend is also observed for a medium containing living photosynthetic cells of Synechococcus elongatus PCC7942. These results clearly indicate that the phospholipid redox polymers extract photosynthetic electrons mainly from plastoquinone. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Storage stability of marine phospholipids emulsions

    DEFF Research Database (Denmark)

    Lu, Henna Fung Sieng; Nielsen, Nina Skall; Baron, Caroline Pascale

    Marine phospholipids (MPL) are believed to provide more advantages than fish oil from the same source. They are considered to have a better bioavailability, a better resistance towards oxidation and a higher content of polyunsaturated fatty acids such as eicosapentaenoic (EPA) and docosahexaenoic...... acids (DHA) than oily triglycerides (fish oil). Therefore, the objective of this study is to explore the feasibility of using marine phospholipids emulsions as delivery system through investigation of the physical, oxidative and hydrolytic stability of MPL emulsions with or without addition of fish oil....... The effect of initial Peroxide Value, total lipids, phospholipids and antioxidants content on stability of MPL emulsions were studied. The physical stability was investigated through measurement of particle size distribution and creaming stability, which involve measurement of changes (%) in emulsion volume...

  15. Tombusviruses upregulate phospholipid biosynthesis via interaction between p33 replication protein and yeast lipid sensor proteins during virus replication in yeast

    International Nuclear Information System (INIS)

    Barajas, Daniel; Xu, Kai; Sharma, Monika; Wu, Cheng-Yu; Nagy, Peter D.

    2014-01-01

    Positive-stranded RNA viruses induce new membranous structures and promote membrane proliferation in infected cells to facilitate viral replication. In this paper, the authors show that a plant-infecting tombusvirus upregulates transcription of phospholipid biosynthesis genes, such as INO1, OPI3 and CHO1, and increases phospholipid levels in yeast model host. This is accomplished by the viral p33 replication protein, which interacts with Opi1p FFAT domain protein and Scs2p VAP protein. Opi1p and Scs2p are phospholipid sensor proteins and they repress the expression of phospholipid genes. Accordingly, deletion of OPI1 transcription repressor in yeast has a stimulatory effect on TBSV RNA accumulation and enhanced tombusvirus replicase activity in an in vitro assay. Altogether, the presented data convincingly demonstrate that de novo lipid biosynthesis is required for optimal TBSV replication. Overall, this work reveals that a (+)RNA virus reprograms the phospholipid biosynthesis pathway in a unique way to facilitate its replication in yeast cells. - Highlights: • Tombusvirus p33 replication protein interacts with FFAT-domain host protein. • Tombusvirus replication leads to upregulation of phospholipids. • Tombusvirus replication depends on de novo lipid synthesis. • Deletion of FFAT-domain host protein enhances TBSV replication. • TBSV rewires host phospholipid synthesis

  16. Phospholipid layer stabilization via Yb(III) on ITIES and facilitated K(I) transport

    Czech Academy of Sciences Publication Activity Database

    Jaklová Dytrtová, Jana; Navrátil, Tomáš; Mareček, Vladimír

    2011-01-01

    Roč. 76, č. 12 (2011), s. 1917-1930 ISSN 0010-0765 R&D Projects: GA AV ČR IAA400400806; GA ČR GAP206/11/1638 Institutional research plan: CEZ:AV0Z40400503; CEZ:AV0Z40550506 Keywords : phospholipids * membranes * zwitterions Subject RIV: CG - Electrochemistry Impact factor: 1.283, year: 2011

  17. Interference of a short-chain phospholipid with ion transport pathways in frog skin

    DEFF Research Database (Denmark)

    Unmack, M A; Frederiksen, O; Willumsen, N J

    1997-01-01

    The effects of mucosal application of the short-chain phospholipid didecanoyl-L-alpha-phosphatidylcholine (DDPC; with two saturated 10-carbon acyl chains) on active Na+ transport and transepithelial conductance (G) in the frog skin (Rana temporaria) were investigated. Active Na+ transport...... of the frog skin epithelium and opens a paracellular tight junction pathway. Both effects may be caused by incorporation of DDPC in the apical cell membrane....

  18. Phospholipid mediated activation of calcium dependent protein kinase 1 (CaCDPK1 from chickpea: a new paradigm of regulation.

    Directory of Open Access Journals (Sweden)

    Ajay Kumar Dixit

    Full Text Available Phospholipids, the major structural components of membranes, can also have functions in regulating signaling pathways in plants under biotic and abiotic stress. The effects of adding phospholipids on the activity of stress-induced calcium dependent protein kinase (CaCDPK1 from chickpea are reported here. Both autophosphorylation as well as phosphorylation of the added substrate were enhanced specifically by phosphatidylcholine and to a lesser extent by phosphatidic acid, but not by phosphatidylethanolamine. Diacylgylerol, the neutral lipid known to activate mammalian PKC, stimulated CaCDPK1 but at higher concentrations. Increase in V(max of the enzyme activity by these phospholipids significantly decreased the K(m indicating that phospholipids enhance the affinity towards its substrate. In the absence of calcium, addition of phospholipids had no effect on the negligible activity of the enzyme. Intrinsic fluorescence intensity of the CaCDPK1 protein was quenched on adding PA and PC. Higher binding affinity was found with PC (K(½ = 114 nM compared to PA (K(½ = 335 nM. We also found that the concentration of PA increased in chickpea plants under salt stress. The stimulation by PA and PC suggests regulation of CaCDPK1 by these phospholipids during stress response.

  19. Comparison of the membrane-filtration fluorescent antibody test, the enzyme-linked immunosorbent assay, and the polymerase chain reaction to detect Renibacterium salmoninarum in salmon ovarian fluid

    Science.gov (United States)

    Pascho, Ronald J.; Chase, Dorothy M.; McKibben, Constance L.

    1998-01-01

    Ovarian fluid samples from naturally infected chinook salmon (Oncorhynchus tshawytscha) were examined for the presence of Renibacterium salmoninarum by the membrane-filtration fluorescent antibody test (MF-FAT), an antigen capture enzyme-linked immunosorbent assay (ELISA), and a nested polymerase chain reaction (PCR). On the basis of the MF-FAT, 64% (66/103) samples contained detectable levels of R. salmoninarum cells. Among the positive fish, the R. salmoninarum concentrations ranged from 25 cells/ml to 4.3 × 109cells/ml. A soluble antigenic fraction of R. salmoninarum was detected in 39% of the fish (40/103) by the ELISA. The ELISA is considered one of the most sensitive detection methods for bacterial kidney disease in tissues, yet it did not detect R. salmoninarum antigen consistently at bacterial cell concentrations below about 1.3 × 104cells/ml according to the MF-FAT counts. When total DNA was extracted and tested in a nested PCR designed to amplify a 320-base-pair region of the gene encoding a soluble 57-kD protein of R. salmoninarum, 100% of the 100 samples tested were positive. The results provided strong evidence that R. salmoninarum may be present in ovarian fluids thought to be free of the bacterium on the basis of standard diagnostic methods.

  20. Structure and dynamics of water and lipid molecules in charged anionic DMPG lipid bilayer membranes

    International Nuclear Information System (INIS)

    Rønnest, A. K.; Peters, G. H.; Hansen, F. Y.; Taub, H.; Miskowiec, A.

    2016-01-01

    Molecular dynamics simulations have been used to investigate the influence of the valency of counter-ions on the structure of freestanding bilayer membranes of the anionic 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG) lipid at 310 K and 1 atm. At this temperature, the membrane is in the fluid phase with a monovalent counter-ion and in the gel phase with a divalent counter-ion. The diffusion constant of water as a function of its depth in the membrane has been determined from mean-square-displacement calculations. Also, calculated incoherent quasielastic neutron scattering functions have been compared to experimental results and used to determine an average diffusion constant for all water molecules in the system. On extrapolating the diffusion constants inferred experimentally to a temperature of 310 K, reasonable agreement with the simulations is obtained. However, the experiments do not have the sensitivity to confirm the diffusion of a small component of water bound to the lipids as found in the simulations. In addition, the orientation of the dipole moment of the water molecules has been determined as a function of their depth in the membrane. Previous indirect estimates of the electrostatic potential within phospholipid membranes imply an enormous electric field of 10 8 –10 9 V m −1 , which is likely to have great significance in controlling the conformation of translocating membrane proteins and in the transfer of ions and molecules across the membrane. We have calculated the membrane potential for DMPG bilayers and found ∼1 V (∼2 ⋅ 10 8 V m −1 ) when in the fluid phase with a monovalent counter-ion and ∼1.4 V (∼2.8 ⋅ 10 8 V m −1 ) when in the gel phase with a divalent counter-ion. The number of water molecules for a fully hydrated DMPG membrane has been estimated to be 9.7 molecules per lipid in the gel phase and 17.5 molecules in the fluid phase, considerably smaller than inferred experimentally for 1,2-dimyristoyl-sn-glycero-3

  1. Structure and dynamics of water and lipid molecules in charged anionic DMPG lipid bilayer membranes

    Energy Technology Data Exchange (ETDEWEB)

    Rønnest, A. K.; Peters, G. H.; Hansen, F. Y., E-mail: flemming@kemi.dtu.dk [Department of Chemistry, Technical University of Denmark, IK 207 DTU, DK-2800 Lyngby (Denmark); Taub, H.; Miskowiec, A. [Department of Physics and Astronomy and the University of Missouri Research Reactor,University of Missouri, Columbia, Missouri 65211 (United States)

    2016-04-14

    Molecular dynamics simulations have been used to investigate the influence of the valency of counter-ions on the structure of freestanding bilayer membranes of the anionic 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG) lipid at 310 K and 1 atm. At this temperature, the membrane is in the fluid phase with a monovalent counter-ion and in the gel phase with a divalent counter-ion. The diffusion constant of water as a function of its depth in the membrane has been determined from mean-square-displacement calculations. Also, calculated incoherent quasielastic neutron scattering functions have been compared to experimental results and used to determine an average diffusion constant for all water molecules in the system. On extrapolating the diffusion constants inferred experimentally to a temperature of 310 K, reasonable agreement with the simulations is obtained. However, the experiments do not have the sensitivity to confirm the diffusion of a small component of water bound to the lipids as found in the simulations. In addition, the orientation of the dipole moment of the water molecules has been determined as a function of their depth in the membrane. Previous indirect estimates of the electrostatic potential within phospholipid membranes imply an enormous electric field of 10{sup 8}–10{sup 9} V m{sup −1}, which is likely to have great significance in controlling the conformation of translocating membrane proteins and in the transfer of ions and molecules across the membrane. We have calculated the membrane potential for DMPG bilayers and found ∼1 V (∼2 ⋅ 10{sup 8} V m{sup −1}) when in the fluid phase with a monovalent counter-ion and ∼1.4 V (∼2.8 ⋅ 10{sup 8} V m{sup −1}) when in the gel phase with a divalent counter-ion. The number of water molecules for a fully hydrated DMPG membrane has been estimated to be 9.7 molecules per lipid in the gel phase and 17.5 molecules in the fluid phase, considerably smaller than inferred experimentally for 1

  2. Electrospun Phospholipid Fibers as Micro-Encapsulation and Antioxidant Matrices

    DEFF Research Database (Denmark)

    Shekarforoush, Elhamalsadat; Mendes, Ana Carina Loureiro; Baj, Vanessa

    2017-01-01

    Electrospun phospholipid (asolectin) microfibers were investigated as antioxidants and encapsulation matrices for curcumin and vanillin. These phospholipid microfibers exhibited antioxidant properties which increased after the encapsulation of both curcumin and vanillin. The total antioxidant...... capacity (TAC) and the total phenolic content (TPC) of curcumin/phospholipid and vanillin/phospholipid microfibers remained stable over time at different temperatures (refrigerated, ambient) and pressures (vacuum, ambient). ¹H-NMR confirmed the chemical stability of both encapsulated curcumin and vanillin...

  3. Lipids in the Assembly of Membrane Proteins and Organization of Protein Supercomplexes: Implications for Lipid-Linked Disorders

    OpenAIRE

    Bogdanov, Mikhail; Mileykovskaya, Eugenia; Dowhan, William

    2008-01-01

    Lipids play important roles in cellular dysfunction leading to disease. Although a major role for phospholipids is in defining the membrane permeability barrier, phospholipids play a central role in a diverse range of cellular processes and therefore are important factors in cellular dysfunction and disease. This review is focused on the role of phospholipids in normal assembly and organization of the membrane proteins, multimeric protein complexes, and higher order supercomplexes. Since lipi...

  4. Phospholipids of New Zealand Edible Brown Algae.

    Science.gov (United States)

    Vyssotski, Mikhail; Lagutin, Kirill; MacKenzie, Andrew; Mitchell, Kevin; Scott, Dawn

    2017-07-01

    Edible brown algae have attracted interest as a source of beneficial allenic carotenoid fucoxanthin, and glyco- and phospholipids enriched in polyunsaturated fatty acids. Unlike green algae, brown algae contain no or little phosphatidylserine, possessing an unusual aminophospholipid, phosphatidyl-O-[N-(2-hydroxyethyl) glycine], PHEG, instead. When our routinely used technique of 31 P-NMR analysis of phospholipids was applied to the samples of edible New Zealand brown algae, a number of signals corresponding to unidentified phosphorus-containing compounds were observed in total lipids. NI (negative ion) ESI QToF MS spectra confirmed the presence of more familiar phospholipids, and also suggested the presence of PHEG or its isomers. The structure of PHEG was confirmed by comparison with a synthetic standard. An unusual MS fragmentation pattern that was also observed prompted us to synthesise a number of possible candidates, and was found to follow that of phosphatidylhydroxyethyl methylcarbamate, likely an extraction artefact. An unexpected outcome was the finding of ceramidephosphoinositol that has not been reported previously as occurring in brown algae. An uncommon arsenic-containing phospholipid has also been observed and quantified, and its TLC behaviour studied, along with that of the newly synthesised lipids.

  5. Phospholipids as Biomarkers for Excessive Alcohol Use

    Science.gov (United States)

    2013-10-01

    NUMBER Phospholipids as Biomarkers for Excessive Alcohol Use 5b. GRANT NUMBER W81XWH-12-1-0497 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S...suspected of alcohol abuse. Toxicol Lett, 151(1), 235-241. Graham, D. P., Cardon , A. L., & Uhl, G. R. (2008). An update on substance use and treatment

  6. Enzymatic modification of phospholipids forfunctional applications and human nutrition

    DEFF Research Database (Denmark)

    Guo, Zheng; Vikbjerg, Anders / Falk; Xu, Xuebing

    2005-01-01

    analogs based on the latest understanding of pivotal role of phospholipids in manifold biological processes, exploration of remarkable application potentials of phospholipids in meliorating human health, as well as development of new chemical and biotechnological approaches applied to the modification...... design. This will of course provide fundamental bases also for the development of enzymatic technology to produce structured or modified phospholipids....

  7. Plasmonic nanoantenna arrays for surface-enhanced Raman spectroscopy of lipid molecules embedded in a bilayer membrane.

    Science.gov (United States)

    Kühler, Paul; Weber, Max; Lohmüller, Theobald

    2014-06-25

    We demonstrate a strategy for surface-enhanced Raman spectroscopy (SERS) of supported lipid membranes with arrays of plasmonic nanoantennas. Colloidal lithography refined with plasma etching is used to synthesize arrays of triangular shaped gold nanoparticles. Reducing the separation distance between the triangle tips leads to plasmonic coupling and to a strong enhancement of the electromagnetic field in the nanotriangle gap. As a result, the Raman scattering intensity of molecules that are located at this plasmonic "hot-spot" can be increased by several orders of magnitude. The nanoantenna array is then embedded with a supported phospholipid membrane which is fluid at room temperature and spans the antenna gap. This configuration offers the advantage that molecules that are mobile within the bilayer membrane can enter the "hot-spot" region via diffusion and can therefore be measured by SERS without static entrapment or adsorption of the molecules to the antenna itself.

  8. Ionic protein-lipid interaction at the plasma membrane: what can the charge do?

    Science.gov (United States)

    Li, Lunyi; Shi, Xiaoshan; Guo, Xingdong; Li, Hua; Xu, Chenqi

    2014-03-01

    Phospholipids are the major components of cell membranes, but they have functional roles beyond forming lipid bilayers. In particular, acidic phospholipids form microdomains in the plasma membrane and can ionically interact with proteins via polybasic sequences, which can have functional consequences for the protein. The list of proteins regulated by ionic protein-lipid interaction has been quickly expanding, and now includes membrane proteins, cytoplasmic soluble proteins, and viral proteins. Here we review how acidic phospholipids in the plasma membrane regulate protein structure and function via ionic interactions, and how Ca(2+) regulates ionic protein-lipid interactions via direct and indirect mechanisms. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Phospholipids and protein adaptation of Pseudomonas sp. to the xenoestrogen tributyltin chloride (TBT).

    Science.gov (United States)

    Bernat, Przemysław; Siewiera, Paulina; Soboń, Adrian; Długoński, Jerzy

    2014-09-01

    A tributyltin (TBT)-resistant strain of Pseudomonas sp. isolated from an overworked car filter was tested for its adaptation to TBT. The isolate was checked for organotin degradation ability, as well as membrane lipid and cellular protein composition in the presence of TBT. The phospholipid profiles of bacteria, grown with and without increased amounts of TBT, were characterized using liquid chromatography/electrospray ionization/mass spectrometry. The strain reacted to the biocide by changing the composition of its phospholipids. TBT induced a twofold decline in the amounts of many molecular species of phosphatidylglycerol and an increase in the levels of phosphatidic acid (by 58%) and phosphatidylethanolamine (by 70%). An increase in the degree of saturation of phospholipid fatty acids of TBT exposed Pseudomonas sp. was observed. These changes in the phospholipid composition and concentration reflect the mechanisms which support optimal lipid ordering in the presence of toxic xenobiotic. In the presence of TBT the abundances of 16 proteins, including TonB-dependent receptors, porins and peroxidases were modified, which could indicate a contribution of some enzymes to TBT resistance.

  10. Phospholipid Binding Protein C Inhibitor (PCI) Is Present on Microparticles Generated In Vitro and In Vivo

    Science.gov (United States)

    Einfinger, Katrin; Badrnya, Sigrun; Furtmüller, Margareta; Handschuh, Daniela; Lindner, Herbert; Geiger, Margarethe

    2015-01-01

    Protein C inhibitor is a secreted, non-specific serine protease inhibitor with broad protease reactivity. It binds glycosaminoglycans and anionic phospholipids, which can modulate its activity. Anionic phospholipids, such as phosphatidylserine are normally localized to the inner leaflet of the plasma membrane, but are exposed on activated and apoptotic cells and on plasma membrane-derived microparticles. In this report we show by flow cytometry that microparticles derived from cultured cells and activated platelets incorporated protein C inhibitor during membrane blebbing. Moreover, protein C inhibitor is present in/on microparticles circulating in normal human plasma as judged from Western blots, ELISAs, flow cytometry, and mass spectrometry. These plasma microparticles are mainly derived from megakaryocytes. They seem to be saturated with protein C inhibitor, since they do not bind added fluorescence-labeled protein C inhibitor. Heparin partially removed microparticle-bound protein C inhibitor, supporting our assumption that protein C inhibitor is bound via phospholipids. To assess the biological role of microparticle-bound protein C inhibitor we performed protease inhibition assays and co-precipitated putative binding partners on microparticles with anti-protein C inhibitor IgG. As judged from amidolytic assays microparticle-bound protein C inhibitor did not inhibit activated protein C or thrombin, nor did microparticles modulate the activity of exogenous protein C inhibitor. Among the proteins co-precipitating with protein C inhibitor, complement factors, especially complement factor 3, were most striking. Taken together, our data do not support a major role of microparticle-associated protein C inhibitor in coagulation, but rather suggest an interaction with proteins of the complement system present on these phospholipid vesicles. PMID:26580551

  11. The Phospholipid Profile of Mycoplasmas

    Directory of Open Access Journals (Sweden)

    Jonathan D. Kornspan

    2012-01-01

    Full Text Available The de novo synthesized polar lipids of Mycoplasma species are rather simple, comprising primarily of the acidic glycerophospholipids PG and CL. In addition, when grown in a medium containing serum, significant amounts of PC and SPM are incorporated into the mycoplasma cell membrane although these lipids are very uncommon in wall-covered bacteria. The exogenous lipids are either incorporated unchanged or the PC incorporated is modified by a deacylation-acylation enzymatic cycle to form disaturated PC. Although their small genome, in some Mycoplasma species, other genes involved in lipid biosynthesis were detected, resulting in the synthesis of a variety of glycolipis, phosphoglycolipids and ether lipids. We suggest that analyses and comparisons of mycoplasma polar lipids may serve as a novel and useful tool for classification. Nonetheless, to evaluate the importance of polar lipids in mycoplasma, further systematic and extensive studies on more Mycoplasma species are needed. While studies are needed to elucidate the role of lipids in the mechanisms governing the interaction of mycoplasmas with host eukaryotic cells, the finding that a terminal phosphocholine containing glycolipids of M. fermentans serves both as a major immune determinants and as a trigger of the inflammatory responses, and the findings that the fusogenicity of M. fermentans with host cells is markedly stimulated by lyso-ether lipids, are important steps toward understanding the molecular mechanisms of M. fermentans pathogenicity.

  12. Plasma membrane Ca2+-ATPase 4 in murine epididymis: secretion of splice variants in the luminal fluid and a role in sperm maturation.

    Science.gov (United States)

    Patel, Ramkrishna; Al-Dossary, Amal A; Stabley, Deborah L; Barone, Carol; Galileo, Deni S; Strehler, Emanuel E; Martin-DeLeon, Patricia A

    2013-07-01

    Plasma membrane Ca(2+)-ATPase isoform 4 (PMCA4) is the primary Ca(2+) efflux pump in murine sperm, where it regulates motility. In Pmca4 null sperm, motility loss results in infertility. We have shown that murine sperm PMCA4b interacts with Ca(2+)/CaM-dependent serine kinase (CASK) in regulating Ca(2+) homeostasis and motility. However, recent work indicated that the bovine PMCA4a splice variant (missing in testis) is epididymally expressed, along with 4b, and may be transferred to sperm. Here we show, via conventional and in situ RT-PCR, that both the splice variants of Pmca4 mRNA are expressed in murine testis and throughout the epididymis. Immunofluorescence localized PMCA4a to the apical membrane of the epididymal epithelium, and Western analysis not only confirmed its presence but showed for the first time that PMCA4a and PMCA4b are secreted in the epididymal luminal fluid (ELF), from which epididymosomes containing PMCA4a were isolated. Flow cytometry indicated the presence of PMCA4a on mature caudal sperm where it was increased ~5-fold compared to caput sperm (detected by Western blotting) and ~2-fold after incubation in ELF, revealing in vitro uptake and implicating PMCA4a in epididymal sperm maturation. Coimmunoprecipitation using pan-PMCA4 antibodies, revealed that both variants associate with CASK, suggesting their presence in a complex. Because they have different kinetic properties for Ca(2+) transport and different abilities to bind to CASK, our study suggests a mechanism for combining the functional attributes of both PMCA4 variants, leading to heightened efficiency of the pump in the maintenance of Ca(2+) homeostasis, which is crucial for normal motility and male fertility.

  13. Electrospun Phospholipid Fibers as Micro-Encapsulation and Antioxidant Matrices.

    Science.gov (United States)

    Shekarforoush, Elhamalsadat; Mendes, Ana C; Baj, Vanessa; Beeren, Sophie R; Chronakis, Ioannis S

    2017-10-17

    Electrospun phospholipid (asolectin) microfibers were investigated as antioxidants and encapsulation matrices for curcumin and vanillin. These phospholipid microfibers exhibited antioxidant properties which increased after the encapsulation of both curcumin and vanillin. The total antioxidant capacity (TAC) and the total phenolic content (TPC) of curcumin/phospholipid and vanillin/phospholipid microfibers remained stable over time at different temperatures (refrigerated, ambient) and pressures (vacuum, ambient). ¹H-NMR confirmed the chemical stability of both encapsulated curcumin and vanillin within phospholipid fibers. Release studies in aqueous media revealed that the phenolic bioactives were released mainly due to swelling of the phospholipid fiber matrix over time. The above studies confirm the efficacy of electrospun phospholipid microfibers as encapsulation and antioxidant systems.

  14. Electrospun Phospholipid Fibers as Micro-Encapsulation and Antioxidant Matrices

    Directory of Open Access Journals (Sweden)

    Elhamalsadat Shekarforoush

    2017-10-01

    Full Text Available Electrospun phospholipid (asolectin microfibers were investigated as antioxidants and encapsulation matrices for curcumin and vanillin. These phospholipid microfibers exhibited antioxidant properties which increased after the encapsulation of both curcumin and vanillin. The total antioxidant capacity (TAC and the total phenolic content (TPC of curcumin/phospholipid and vanillin/phospholipid microfibers remained stable over time at different temperatures (refrigerated, ambient and pressures (vacuum, ambient. 1H-NMR confirmed the chemical stability of both encapsulated curcumin and vanillin within phospholipid fibers. Release studies in aqueous media revealed that the phenolic bioactives were released mainly due to swelling of the phospholipid fiber matrix over time. The above studies confirm the efficacy of electrospun phospholipid microfibers as encapsulation and antioxidant systems.

  15. Identification of unusual phospholipid fatty acyl compositions of Acanthamoeba castellanii.

    Directory of Open Access Journals (Sweden)

    Marta Palusinska-Szysz

    Full Text Available Acanthamoeba are opportunistic protozoan pathogens that may lead to sight-threatening keratitis and fatal granulomatous encephalitis. The successful prognosis requires early diagnosis and differentiation of pathogenic Acanthamoeba followed by aggressive treatment regimen. The plasma membrane of Acanthamoeba consists of 25% phospholipids (PL. The presence of C20 and, recently reported, 28- and 30-carbon fatty acyl residues is characteristic of amoeba PL. A detailed knowledge about this unusual PL composition could help to differentiate Acanthamoeba from other parasites, e.g. bacteria and develop more efficient treatment strategies. Therefore, the detailed PL composition of Acanthamoeba castellanii was investigated by 31P nuclear magnetic resonance spectroscopy, thin-layer chromatography, gas chromatography, high performance liquid chromatography and liquid chromatography-mass spectrometry. Normal and reversed phase liquid chromatography coupled with mass spectrometric detection was used for detailed characterization of the fatty acyl composition of each detected PL. The most abundant fatty acyl residues in each PL class were octadecanoyl (18∶0, octadecenoyl (18∶1 Δ9 and hexadecanoyl (16∶0. However, some selected PLs contained also very long fatty acyl chains: the presence of 28- and 30-carbon fatty acyl residues was confirmed in phosphatidylethanolamine (PE, phosphatidylserine, phosphatidic acid and cardiolipin. The majority of these fatty acyl residues were also identified in PE that resulted in the following composition: 28∶1/20∶2, 30∶2/18∶1, 28∶0/20∶2, 30∶2/20∶4 and 30∶3/20∶3. The PL of amoebae are significantly different in comparison to other cells: we describe here for the first time unusual, very long chain fatty acids with Δ5-unsaturation (30∶35,21,24 and 30∶221,24 localized exclusively in specific phospholipid classes of A. castellanii protozoa that could serve as specific biomarkers for the presence of

  16. Rationalization of reduced penetration of drugs through ceramide gel phase membrane.

    Science.gov (United States)

    Paloncýová, Markéta; DeVane, Russell H; Murch, Bruce P; Berka, Karel; Otyepka, Michal

    2014-11-25

    Since computing resources have advanced enough to allow routine molecular simulation studies of drug molecules interacting with biologically relevant membranes, a considerable amount of work has been carried out with fluid phospholipid systems. However, there is very little work in the literature on drug interactions with gel phase lipids. This poses a significant limitation for understanding permeation through the stratum corneum where the primary pathway is expected to be through a highly ordered lipid matrix. To address this point, we analyzed the interactions of p-aminobenzoic acid (PABA) and its ethyl (benzocaine) and butyl (butamben) esters with two membrane bilayers, which differ in their fluidity at ambient conditions. We considered a dioleoylphosphatidylcholine (DOPC) bilayer in a fluid state and a ceramide 2 (CER2, ceramide NS) bilayer in a gel phase. We carried out unbiased (100 ns long) and biased z-constraint molecular dynamics simulations and calculated the free energy profiles of all molecules along the bilayer normal. The free energy profiles converged significantly slower for the gel phase. While the compounds have comparable affinities for both membranes, they exhibit penetration barriers almost 3 times higher in the gel phase CER2 bilayer. This elevated barrier and slower diffusion in the CER2 bilayer, which are caused by the high ordering of CER2 lipid chains, explain the low permeability of the gel phase membranes. We also compared the free energy profiles from MD simulations with those obtained from COSMOmic. This method provided the same trends in behavior for the guest molecules in both bilayers; however, the penetration barriers calculated by COSMOmic did not differ between membranes. In conclusion, we show how membrane fluid properties affect the interaction of drug-like molecules with membranes.

  17. Mesenchymal Stem/Progenitor Cells Derived from Articular Cartilage, Synovial Membrane and Synovial Fluid for Cartilage Regeneration: Current Status and Future Perspectives.

    Science.gov (United States)

    Huang, Yi-Zhou; Xie, Hui-Qi; Silini, Antonietta; Parolini, Ornella; Zhang, Yi; Deng, Li; Huang, Yong-Can

    2017-10-01

    Large articular cartilage defects remain an immense challenge in the field of regenerative medicine because of their poor intrinsic repair capacity. Currently, the available medical interventions can relieve clinical symptoms to some extent, but fail to repair the cartilaginous injuries with authentic hyaline cartilage. There has been a surge of interest in developing cell-based therapies, focused particularly on the use of mesenchymal stem/progenitor cells with or without scaffolds. Mesenchymal stem/progenitor cells are promising graft cells for tissue regeneration, but the most suitable source of cells for cartilage repair remains controversial. The tissue origin of mesenchymal stem/progenitor cells notably influences the biological properties and therapeutic potential. It is well known that mesenchymal stem/progenitor cells derived from synovial joint tissues exhibit superior chondrogenic ability compared with those derived from non-joint tissues; thus, these cell populations are considered ideal sources for cartilage regeneration. In addition to the progress in research and promising preclinical results, many important research questions must be answered before widespread success in cartilage regeneration is achieved. This review outlines the biology of stem/progenitor cells derived from the articular cartilage, the synovial membrane, and the synovial fluid, including their tissue distribution, function and biological characteristics. Furthermore, preclinical and clinical trials focusing on their applications for cartilage regeneration are summarized, and future research perspectives are discussed.

  18. Phospholipids as Biomarkers for Excessive Alcohol Use

    Science.gov (United States)

    2016-10-01

    is designed to evaluate the utility of levels of two phospholipids in serum as a marker of past drinking behavior across month- level time horizons...in an attempt to improve ability to measure alcohol quantity consumed and associated damage better than can be done with ethyl alcohol level measures...and other existing tests that only measure very recent exposure and poorly reflect quantity consumed . This will be achieved by correlating detailed

  19. Phospholipids and their degrading enzyme in the tears of soft contact lens wearers.

    Science.gov (United States)

    Yamada, Masakazu; Mochizuki, Hiroshi; Kawashima, Motoko; Hata, Seiichiro

    2006-12-01

    Low tear phospholipids levels are associated with tear film instability in soft contact lens wearers. We assayed levels of phospholipids and their degrading enzyme secretory phospholipase A2 (sPLA2) both in tears and deposited on contact lenses composed of 2 hydrophilic materials after 1 day of routine use. Polymacon (Medalist; FDA group 1, low water/nonionic) and Etafilcon A (One Day Acuvue; group 4, high water/ionic) contact lenses were worn for 12 hours by 16 experienced contact lens wearers. Phospholipids in tear fluids and deposited on contact lenses were estimated by phosphorus determination with ammonium molybdate through enzymatic digestion. Double-antibody sandwich ELISA was used to determine group IIa sPLA2 concentrations, and sPLA2 activity was assayed using 1,2-diheptanoyl thio-phosphatidylcholine as substrate. Phospholipids concentrations in tears with Polymacon and Etafilcon A were 186 +/- 39 and 162 +/- 33 microg/mL, respectively. The latter concentration was significantly lower than that observed in the same subjects when not wearing contact lenses (P = 0.0023). In tears, both group IIa sPLA2 concentrations and enzymatic activity remained unchanged, regardless of lens wearing. However, Etafilcon A (0.57 +/- 0.09 microg/lens) showed more group IIa sPLA2 deposition than Polymacon (0.01 +/- 0.01 microg/lens; P < 0.001). Furthermore, group IIa sPLA2 deposited on Etafilcon A but not on Polymacon lenses retained its enzymatic activity. Significant differences of group IIa sPLA2 deposition were found in the 2 lenses tested. Such deposition might induce phospholipid hydrolysis in tears and thereby promote tear film instability in hydrophilic contact lens wearers.

  20. Milk phospholipids: Organic milk and milk rich in conjugated linoleic acid compared with conventional milk.

    Science.gov (United States)

    Ferreiro, T; Gayoso, L; Rodríguez-Otero, J L

    2015-01-01

    The objective of this study was to compare the phospholipid content of conventional milk with that of organic milk and milk rich in conjugated linoleic acid (CLA). The membrane enclosing the fat globules of milk is composed, in part, of phospholipids, which have properties of interest for the development of so-called functional foods and technologically novel ingredients. They include phosphatidylethanolamine (PE), phosphatidylinositol (PI), phosphatidylcholine (PC), phosphatidylserine (PS), and the sphingophospholipid sphingomyelin (SM). Milk from organically managed cows contains higher levels of vitamins, antioxidants, and unsaturated fatty acids than conventionally produced milk, but we know of no study with analogous comparisons of major phospholipid contents. In addition, the use of polyunsaturated-lipid-rich feed supplement (extruded linseed) has been reported to increase the phospholipid content of milk. Because supplementation with linseed and increased unsaturated fatty acid content are the main dietary modifications used for production of CLA-rich milk, we investigated whether these modifications would lead to this milk having higher phospholipid content. We used HPLC with evaporative light scattering detection to determine PE, PI, PC, PS, and SM contents in 16 samples of organic milk and 8 samples of CLA-rich milk, in each case together with matching reference samples of conventionally produced milk taken on the same days and in the same geographical areas as the organic and CLA-rich samples. Compared with conventional milk and milk fat, organic milk and milk fat had significantly higher levels of all the phospholipids studied. This is attributable to the differences between the 2 systems of milk production, among which the most influential are probably differences in diet and physical exercise. The CLA-rich milk fat had significantly higher levels of PI, PS, and PC than conventional milk fat, which is also attributed to dietary differences: rations for

  1. Using neurolipidomics to identify phospholipid mediators of synaptic (dysfunction in Alzheimer’s Disease

    Directory of Open Access Journals (Sweden)

    Steffany A L Bennett

    2013-07-01

    Full Text Available Not all of the mysteries of life lie in our genetic code. Some can be found buried in our membranes. These shells of fat, sculpted in the central nervous system into the cellular (and subcellular boundaries of neurons and glia, are themselves complex systems of information. The diversity of neural phospholipids, coupled with their chameleon-like capacity to transmute into bioactive molecules, provides a vast repertoire of immediate response second messengers. The effects of compositional changes on synaptic function have only begun to be appreciated. Here, we mined 29 different neurolipidomic datasets for changes in neuronal membrane phospholipid metabolism in Alzheimer’s Disease. Three overarching metabolic disturbances were detected. We found that an increase in the hydrolysis of platelet activating factor precursors and ethanolamine-containing plasmalogens, coupled with a failure to regenerate relatively rare alkyl-acyl and alkenyl-acyl structural phospholipids, correlated with disease severity. Accumulation of specific bioactive metabolites (i.e., PC(O-16:0/2:0 and PE(P-16:0/0:0 was associated with aggravating tau pathology, enhancing vesicular release, and signaling neuronal loss. Finally, depletion of PI(16:0/20:4, PI(16:0/22:6, and PI(18:0/22:6 was implicated in accelerating Aβ42 biogenesis. Our analysis further suggested that converging disruptions in platelet activating factor, plasmalogen, phosphoinositol and phosphoethanolamine, and docosahexaenoic acid metabolism may contribute mechanistically to catastrophic vesicular depletion, impaired receptor trafficking, and morphological dendritic deformation. Together, this analysis supports an emerging hypothesis that aberrant phospholipid metabolism may be one of multiple critical determinants required for Alzheimer disease conversion.

  2. Membrane phosphorylation and nerve cell function

    International Nuclear Information System (INIS)

    Baer, P.R.

    1982-01-01

    This thesis deals with the phosphorylation of membrane components. In part I a series of experiments is described using the hippocampal slice as a model system. In part II a different model system - cultured hybrid cells - is used to study protein and lipid phosphorylation, influenced by incubation with neuropeptides. In part III in vivo and in vitro studies are combined to study protein phosphorylation after neuroanatomical lesions. In a section of part II (Page 81-90) labelling experiments of the membrane inositol-phospholipids are described. 32 P-ATP was used to label phospholipids in intact hybrid cells, and short incubations were found to be the most favourable. (C.F.)

  3. Porphyrin-phospholipid interaction and ring metallation depending on the phospholipid polar head type.

    Science.gov (United States)

    Ramos, Ana P; Pavani, Christiane; Iamamoto, Yassuko; Zaniquelli, Maria E D

    2010-10-01

    The interaction between a hydrophobically modified 5,10,15,20-tetrakis(4-N-tetradecyl-pyridyl) porphyrin and three phospholipids: two negatively charged, DMPA (the sodium salt of dimyristoyl-sn-glycero-phosphatidyl acid) and DMPG (the sodium salt of 1,2-dimyristoyl-sn-glycero-3-[phospho-rac-(1-glycerol)]) and a zwitterionic DMPC (dimyristoyl-sn-glycero-phosphatidylcholine), were studied by means of surface pressure isotherms and spectroscopic methods. The interaction results in partial or total metallation of the porphyrin with zinc ions in the presence of negatively charged phospholipids, as attested by UV-vis and luminescence spectroscopy of the transferred films. In the presence of the zwitterionic phospholipid no insertion of zinc ion in the porphyrin ring is detected. These results are relevant for the understanding of photosensitizer-lipid-carrier binding for use in photodynamic therapy. Copyright 2010 Elsevier Inc. All rights reserved.

  4. Antidiabetic phospholipid-nuclear receptor complex reveals the mechanism for phospholipid-driven gene regulation

    Energy Technology Data Exchange (ETDEWEB)

    Musille, Paul M; Pathak, Manish C; Lauer, Janelle L; Hudson, William H; Griffin, Patrick R; Ortlund, Eric A [Emory-MED; (Scripps)

    2013-01-31

    The human nuclear receptor liver receptor homolog-1 (LRH-1) has an important role in controlling lipid and cholesterol homeostasis and is a potential target for the treatment of diabetes and hepatic diseases. LRH-1 is known to bind phospholipids, but the role of phospholipids in controlling LRH-1 activation remains highly debated. Here we describe the structure of both apo LRH-1 and LRH-1 in complex with the antidiabetic phospholipid dilauroylphosphatidylcholine (DLPC). Together with hydrogen-deuterium exchange MS and functional data, our studies show that DLPC binding is a dynamic process that alters co-regulator selectivity. We show that the lipid-free receptor undergoes previously unrecognized structural fluctuations, allowing it to interact with widely expressed co-repressors. These observations enhance our understanding of LRH-1 regulation and highlight its importance as a new therapeutic target for controlling diabetes.

  5. 1,2-Dielaidoylphosphocholine/1,2-dimyristoylphosphoglycerol supported phospholipid bilayer formation in calcium and calcium-free buffer

    International Nuclear Information System (INIS)

    Evans, Kervin O.

    2012-01-01

    Phospholipid membranes are useful in the field of biocatalysis because a supported phospholipid membrane can create a biomimetic platform where biocatalytic processes can readily occur. In this work, supported bilayer formation from sonicated phospholipid vesicles containing 1,2-dielaidoyl-sn-glycero-3-phosphocholine and 1,2-dimyristoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] was studied using a quartz crystal microbalance with dissipation monitoring and an atomic force microscope. The molar percentages of DEPC and DMPG were varied to determine the effect of overall lipid composition on supported bilayer formation. This work also explored the effect that calcium ion concentration had on supported bilayer formation. Results show that vesicles with up to 50 mol% dimyristoylphosphoglycerol can form a supported bilayer without the presence of calcium ions; however, supported bilayer formation in calcium buffer was inhibited as the anionic (negatively charged) lipid concentration increased. Data suggest that supported phospholipid bilayer formation in the absence of Ca 2+ from vesicles containing negatively charged lipids is specific to phosphatidylglycerol. - Highlights: ► SPB formation of DEPC vesicles containing 0 to 50 mol% DMPG monitored using QCM-D. ► Ca 2+ inhibited SPB formation of DEPC vesicles containing 30 to 50 mol% DMPG. ► Vesicles containing DMPG at 0 to 50 mol% formed SPB in buffer free of Ca 2+ .

  6. Ice formation in model biological membranes in the presence of cryoprotectors

    Energy Technology Data Exchange (ETDEWEB)

    Kiselev, M.A. E-mail: kiselev@nf.jinr.ru; Lesieur, P.; Kisselev, A.M.; Ollivon, M

    2000-06-21

    Ice formation in model biological membranes is studied by SAXS and WAXS in the presence of cryoprotectors: dimethyl sulfoxide and glycerol. Three types of phospholipid membranes: DPPC, DMPC, DSPC are chosen for the investigation as well-studied model biological membranes. A special cryostat is used for sample cooling from 14.1 deg. C to -55.4 deg. C. The ice formation is detected only by WAXS in binary phospholipid/water and ternary phospholipid/cryoprotector/water systems in the condition of excess solvent. Ice formation in a binary phospholipid/water system creates an abrupt decrease of the membrane repeat distance by {delta}d, the so-called ice-induced dehydration of intermembrane space. The value of {delta}d decreases as the cryoprotector concentration increases. The formation of ice does not influence the membrane structure ({delta}d=0) for cryoprotector mole fractions higher than 0.05.

  7. Suppression of phospholipid biosynthesis by cerulenin in the condensed Single-Protein-Production (cSPP) system

    International Nuclear Information System (INIS)

    Mao, Lili; Inoue, Koichi; Tao, Yisong; Montelione, Gaetano T.; McDermott, Ann E.; Inouye, Masayori

    2011-01-01

    Using the single-protein-production (SPP) system, a protein of interest can be exclusively produced in high yield from its ACA-less gene in Escherichia coli expressing MazF, an ACA-specific mRNA interferase. It is thus feasible to study a membrane protein by solid-state NMR (SSNMR) directly in natural membrane fractions. In developing isotope-enrichment methods, we observed that 13 C was also incorporated into phospholipids, generating spurious signals in SSNMR spectra. Notable, with the SPP system a protein can be produced in total absence of cell growth caused by antibiotics. Here, we demonstrate that cerulenin, an inhibitor of phospholipid biosynthesis, can suppress isotope incorporation in the lipids without affecting membrane protein yield in the SPP system. SSNMR analysis of ATP synthase subunit c, an E. coli inner membrane protein, produced by the SPP method using cerulenin revealed that 13 C resonance signals from phospholipid were markedly reduced, while signals for the isotope-enriched protein were clearly present.

  8. Layer-by-layer cell membrane assembly

    Science.gov (United States)

    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.

  9. Peritoneal Fluid Analysis

    Science.gov (United States)

    ... Get Tested? To help diagnose the cause of peritonitis, an inflammation of the membrane lining the abdomen, ... fever and your healthcare practitioner suspects you have peritonitis or ascites Sample Required? A peritoneal fluid sample ...

  10. Platelet activating factor activity in the phospholipids of bovine spermatozoa

    Energy Technology Data Exchange (ETDEWEB)

    Parks, J.E.; Hough, S.; Elrod, C. (Cornell Univ., Ithaca, NY (USA))

    1990-11-01

    Platelet activating factor (PAF) has been detected in sperm from several mammalian species and can affect sperm motility and fertilization. Because bovine sperm contain a high percentage of ether-linked phospholipid precursors required for PAF synthesis, a study was undertaken to determine the PAF activity of bovine sperm phospholipids. Total lipids of washed, ejaculated bull sperm were extracted, and phospholipids were fractionated by thin-layer chromatography. Individual phospholipid fractions were assayed for PAF activity on the basis of (3H)serotonin release from equine platelets. PAF activity was detected in the PAF fraction (1.84 pmol/mumol total phospholipid) and in serine/inositol (PS/PI), choline (CP), and ethanolamine phosphoglyceride (EP) and cardiolipin (CA) fractions. Activity was highest in the CP fraction (8.05 pmol/mumol total phospholipid). Incomplete resolution of PAF and neutral lipids may have contributed to the activity in the PS/PI and CA fractions, respectively. Phospholipids from nonsperm sources did not stimulate serotonin release. Platelet activation by purified PAF and by sperm phospholipid fractions was inhibited by the receptor antagonist SRI 63-675. These results indicate that bovine sperm contain PAF and that other sperm phospholipids, especially CP and EP, which are high in glycerylether components, are capable of receptor-mediated platelet activation.

  11. Apolipoprotein L1 confers pH-switchable ion permeability to phospholipid vesicles.

    Science.gov (United States)

    Bruno, Jonathan; Pozzi, Nicola; Oliva, Jonathan; Edwards, John C

    2017-11-03

    Apolipoprotein L1 (ApoL1) is a human serum protein conferring resistance to African trypanosomes, and certain ApoL1 variants increase susceptibility to some progressive kidney diseases. ApoL1 has been hypothesized to function like a pore-forming colicin and has been reported to have permeability effects on both intracellular and plasma membranes. Here, to gain insight into how ApoL1 may function in vivo , we used vesicle-based ion permeability, direct membrane association, and intrinsic fluorescence to study the activities of purified recombinant ApoL1. We found that ApoL1 confers chloride-selective permeability to preformed phospholipid vesicles and that this selectivity is strongly pH-sensitive, with maximal activity at pH 5 and little activity above pH 7. When ApoL1 and lipid were allowed to interact at low pH and were then brought to neutral pH, chloride permeability was suppressed, and potassium permeability was activated. Both chloride and potassium permeability linearly correlated with the mass of ApoL1 in the reaction mixture, and both exhibited lipid selectivity, requiring the presence of negatively charged lipids for activity. Potassium, but not chloride, permease activity required the presence of calcium ions in both the association and activation steps. Direct assessment of ApoL1-lipid associations confirmed that ApoL1 stably associates with phospholipid vesicles, requiring low pH and the presence of negatively charged phospholipids for maximal binding. Intrinsic fluorescence of ApoL1 supported the presence of a significant structural transition when ApoL1 is mixed with lipids at low pH. This pH-switchable ion-selective permeability may explain the different effects of ApoL1 reported in intracellular and plasma membrane environments. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  12. Frequency-dependent electrodeformation of giant phospholipid vesicles in AC electric field

    Science.gov (United States)

    2010-01-01

    A model of vesicle electrodeformation is described which obtains a parametrized vesicle shape by minimizing the sum of the membrane bending energy and the energy due to the electric field. Both the vesicle membrane and the aqueous media inside and outside the vesicle are treated as leaky dielectrics, and the vesicle itself is modeled as a nearly spherical shape enclosed within a thin membrane. It is demonstrated (a) that the model achieves a good quantitative agreement with the experimentally determined prolate-to-oblate transition frequencies in the kilohertz range and (b) that the model can explain a phase diagram of shapes of giant phospholipid vesicles with respect to two parameters: the frequency of the applied alternating current electric field and the ratio of the electrical conductivities of the aqueous media inside and outside the vesicle, explored in a recent paper (S. Aranda et al., Biophys J 95:L19–L21, 2008). A possible use of the frequency-dependent shape transitions of phospholipid vesicles in conductometry of microliter samples is discussed. PMID:21886342

  13. Neutron reflectivity study of substrate surface chemistry effects on supported phospholipid bilayer formation on (1120) sapphire.

    Energy Technology Data Exchange (ETDEWEB)

    Oleson, Timothy A. [University of Wisconsin, Madison; Sahai, Nita [University of Akron; Wesolowski, David J [ORNL; Dura, Joseph A [ORNL; Majkrzak, Charles F [ORNL; Giuffre, Anthony J. [University of Wisconsin, Madison

    2012-01-01

    Oxide-supported phospholipid bilayers (SPBs) used as biomimetric membranes are significant for a broad range of applications including improvement of biomedical devices and biosensors, and in understanding biomineralization processes and the possible role of mineral surfaces in the evolution of pre-biotic membranes. Continuous-coverage and/or stacjed SPBs retain properties (e.,g. fluidity) more similar to native biological membranes, which is desirable for most applications. Using neutron reflectivity, we examined face coverage and potential stacking of dipalmitoylphosphatidylcholine (DPPC) bilayers on the (1120) face of sapphire (a-Al2O3). Nearly full bilayers were formed at low to neutral pH, when the sapphire surface is positively charged, and at low ionic strength (l=15 mM NaCl). Coverage decreased at higher pH, close to the isoelectric point of sapphire, and also at high I>210mM, or with addition of 2mM Ca2+. The latter two effects are additive, suggesting that Ca2+ mitigates the effect of higher I. These trends agree with previous results for phospholipid adsorption on a-Al2O3 particles determined by adsorption isotherms and on single-crystal (1010) sapphire by atomic force microscopy, suggesting consistency of oxide surface chemistry-dependent effects across experimental techniques.

  14. Isolation and Analysis of Phospholipids in Dairy Foods

    Directory of Open Access Journals (Sweden)

    Lígia Pimentel

    2016-01-01

    Full Text Available The lipid fraction of milk is one of the most complex matrixes in foodstuffs due to the presence of a high number of moieties with different physical and chemical properties. Glycerolipids include glycerol and two fatty acids esterified in positions sn-1 and sn-2 with higher concentration of unsaturated fatty acids than in the triglyceride fraction of milk. Sphingolipids consist of a sphingoid base linked to a fatty acid across an amide bond. Their amphiphilic nature makes them suitable to be added into a variety of foods and recent investigations show that phospholipids, mainly phosphatidylserine and sphingomyelin, can exert antimicrobial, antiviral, and anticancer activities as well as positive effects in Alzheimer’s disease, stress, and memory decline. Polar lipids can be found as natural constituents in the membranes of all living organisms with soybean and eggs as the principal industrial sources, yet they have low contents in phosphatidylserine and sphingomyelin. Animal products are rich sources of these compounds but since there are legal restrictions to avoid transmission of prions, milk and dairy products are gaining interest as alternative sources. This review summarizes the analysis of polar lipids in dairy products including sample preparation (extraction and fractionation/isolation and analysis by GC or HPLC and the latest research works using ELSD, CAD, and MS detectors.

  15. Bilayer/cytoskeleton interactions in lipid-symmetric erythrocytes assessed by a photoactivable phospholipid analogue

    International Nuclear Information System (INIS)

    Pradhan, D.; Schlegel, R.A.; Williamson, P.

    1991-01-01

    Two mechanisms have been proposed for maintenance of transbilayer phospholipid asymmetry in the erythrocyte plasma membrane, one involving specific interactions between the aminophospholipids of the inner leaflet of the bilayer and the cytoskeleton, particularly spectrin, and the other involving the aminophospholipid translocase. If the former mechanism is correct, then erythrocytes which have lost their asymmetric distribution of phospholipids should display altered bilayer/cytoskeleton interactions. To test this possibility, normal erythrocytes, erythrocytes from patients with chronic myelogenous leukemia or sickle disease, and lipid-symmetric and -asymmetric erythrocyte ghosts were labeled with the radioactive photoactivable analogue of phosphatidylethanolamine, 2-(2-azido-4-nitrobenzoyl)-1-acyl-sn-glycero-3-phospho[ 14 C] ethanolamine ([ 14 C]AzPE), previously shown to label cytoskeletal proteins from the bilayer. The labeling pattern of cytoskeletal proteins in pathologic erythrocytes and lipid-asymmetric erythrocyte ghosts was indistinguishable from normal erythrocytes, indicating that the probe detects no differences in bilayer/cytoskeleton interactions in these cells. In contrast, in lipid-symmetric erythrocyte ghosts, labeling of bands 4.1 and 4.2 and actin, and to a lesser extent ankyrin, by [ 14 C]AzPE was considerably reduced. Significantly, however, labeling of spectrin was unaltered in the lipid-symmetric cells. These results do not support a model in which spectrin is involved in the maintenance of an asymmetric distribution of phospholipids in erythrocytes

  16. Improved stability of highly fluorinated phospholipid-based vesicles in the presence of bile salts.

    Science.gov (United States)

    Gadras, C; Santaella, C; Vierling, P

    1999-01-04

    The stability of fluorinated phospholipid-based vesicles in terms of detergent-induced release of encapsulated carboxyfluorescein has been evaluated. The fluorinated liposomes are substantially more resistant towards the lytic action of sodium taurocholate than conventional DSPC or even DSPC/CH 1/1 liposomes. Concerning structure/permeability relationships, the larger the fluorination degree of the membrane, the higher the resistance of the fluorinated liposomes to their destruction by the detergent. These results show that fluorinated liposomes have a promising potential as drug carrier and delivery systems for oral administration.

  17. Emulsifying triglycerides with dairy phospholipids instead of soy lecithin modulates gut lipase activity

    DEFF Research Database (Denmark)

    Mathiassen, Jakob Hovalt; Nejrup, Rikke Guldhammer; Frøkiær, Hanne

    2015-01-01

    in particular to limit fatty acid absorption in babies given infant formulas. Since interaction between the lipid droplet and the gastric and duodenal lipases occur through the hydrophobic/hydrophilic interface, the composition of the emulsifier may be crucial for efficient hydrolysis. We therefore determined...... hydrolytic rate of gastric lipase and pancreatic lipase, on their own or pancreatic lipase after gastric lipase on TAG droplets of similar size emulsified in either soy lecithin (SL) or in bovine milk phospholipids (MPL), more similar to human milk globule membrane lipids than soy lecithin. Gastric lipase...... for formulas for term-born infants....

  18. Angiotensin and bradykinin interactions with phospholipids

    International Nuclear Information System (INIS)

    Elliott, M.E.; Goodfriend, T.L.

    1979-01-01

    Reversible interactions were demonstrated between some phospholipids and some polypeptides related to angiotensin and bradykinin. The extent of the interaction was dependent on the structures of the lipid and peptide. The naturally occurring compounds that interacted most avidly were cardiolipin and (des-Asp 1 )-angiotensins. The apparent dissociation constant of this complex in chloroform was 10 -5 M. The complex contained more than one cardiolipin molecule/molecule of peptide. Kinins interacted most strongly with lecithin. The phospholipids altered the chromatographic behaviour of radioiodinated derivatives of the polypeptides, and solubilized radioactive and unlabeled polypeptides in chloroform. In aqueous media, cardiolipin suspensions preferentially bound (des-Asp 1 )-angiotensin II, and inhibited its binding by antibody. The interactions were sensitive to pH and cations in the aqueous phase, and were reversed by some reagents added to the organic phase. These interactions have direct implications for binding reactions of peptides in vitro, and may bear upon the actions of the hormones in vivo. (Auth.)

  19. Dynamic assembly of MinD into filament bundles modulated by ATP, phospholipids, and MinE

    OpenAIRE

    Suefuji, Kyoko; Valluzzi, Regina; RayChaudhuri, Debabrata

    2002-01-01

    Accurate positioning of the division septum at the equator of Escherichia coli cells requires a rapid oscillation of MinD ATPase between the polar halves of the cell membrane, together with the division inhibitor MinC, under MinE control. The mechanism underlying MinD oscillation remains poorly understood. Here, we demonstrate that purified MinD assembles into protein filaments in the presence of ATP. Incubation with phospholipid vesicles further stimulates MinD polymerization. Addition of pu...

  20. 1-Oleoyl-2-acetylglycerol stimulates 5-lipoxygenase activity via a putative (phospho)lipid binding site within the N-terminal C2-like domain.

    Science.gov (United States)

    Hörnig, Christina; Albert, Dana; Fischer, Lutz; Hörnig, Michael; Rådmark, Olof; Steinhilber, Dieter; Werz, Oliver

    2005-07-22

    5-Lipoxygenase (5-LO) catalysis is positively regulated by Ca2+ ions and phospholipids that both act via the N-terminal C2-like domain of 5-LO. Previously, we have shown that 1-oleoyl-2-acetylglycerol (OAG) functions as an agonist for human polymorphonuclear leukocytes (PMNL) in stimulating 5-LO product formation. Here we have demonstrated that OAG directly stimulates 5-LO catalysis in vitro. In the absence of Ca2+ (chelated using EDTA), OAG strongly and concentration-dependently stimulated crude 5-LO in 100,000 x g supernatants as well as purified 5-LO enzyme from PMNL. Also, the monoglyceride 1-O-oleyl-rac-glycerol and 1,2-dioctanoyl-sn-glycerol were effective, whereas various phospholipids did not stimulate 5-LO. However, in the presence of Ca2+, OAG caused no stimulation of 5-LO. Also, phospholipids or cellular membranes abolished the effects of OAG. As found previously for Ca2+, OAG renders 5-LO activity resistant against inhibition by glutathione peroxidase activity, and this effect of OAG is reversed by phospholipids. Intriguingly, a 5-LO mutant lacking tryptophan residues (Trp-13, -75, and -102) important for the binding of the 5-LO C2-like domain to phospholipids was not stimulated by OAG. We conclude that OAG directly stimulates 5-LO by acting at a phospholipid binding site located within the C2-like domain.

  1. Sensing Phosphatidylserine in Cellular Membranes

    Directory of Open Access Journals (Sweden)

    Jason G. Kay

    2011-01-01

    Full Text Available Phosphatidylserine, a phospholipid with a negatively charged head-group, is an important constituent of eukaryotic cellular membranes. On the plasma membrane, rather than being evenly distributed, phosphatidylserine is found preferentially in the inner leaflet. Disruption of this asymmetry, leading to the appearance of phosphatidylserine on the surface of the cell, is known to play a central role in both apoptosis and blood clotting. Despite its importance, comparatively little is known about phosphatidylserine in cells: its precise subcellular localization, transmembrane topology and intracellular dynamics are poorly characterized. The recent development of new, genetically-encoded probes able to detect phosphatidylserine within live cells, however, is leading to a more in-depth understanding of the biology of this phospholipid. This review aims to give an overview of the current methods for phosphatidylserine detection within cells, and some of the recent realizations derived from their use.

  2. Screening for the drug-phospholipid interaction: correlation to phospholipidosis

    DEFF Research Database (Denmark)

    Alakoskela, Juha-Matti; Vitovic, Pavol; Kinnunen, Paavo K J

    2009-01-01

    Phospholipid bilayers represent a complex, anisotropic environment fundamentally different from bulk oil or octanol, for instance. Even "simple" drug association to phospholipid bilayers can only be fully understood if the slab-of-hydrocarbon approach is abandoned and the complex, anisotropic...

  3. Co-assembly of chitosan and phospholipids into hybrid hydrogels

    DEFF Research Database (Denmark)

    Mendes, Ana Carina Loureiro; Shekarforoush, Elhamalsadat; Engwer, Christoph

    2016-01-01

    Novel hybrid hydrogels were formed by adding chitosan (Ch) to phospholipids (P) self-assembled particles in lactic acid. The effect of the phospholipid concentration on the hydrogel properties was investigated and was observed to affect the rate of hydrogel formation and viscoelastic properties...

  4. Saturated fatty acid in the phospholipid monolayer contributes to the formation of large lipid droplets

    International Nuclear Information System (INIS)

    Arisawa, Kotoko; Mitsudome, Haruka; Yoshida, Konomi; Sugimoto, Shizuka; Ishikawa, Tomoko; Fujiwara, Yoko; Ichi, Ikuyo

    2016-01-01

    The degree of saturation of fatty acid chains in the bilayer membrane structure is known to control membrane fluidity and packing density. However, the significance of fatty acid composition in the monolayers of lipid droplets (LDs) has not been elucidated. In this study, we noted a relationship between the size of LDs and the fatty acid composition of the monolayer. To obtain large LDs, we generated NIH3T3 cells overexpressing fat-specific protein 27 (FSP27). This induced the fusion of LDs, resulting in larger LDs in FSP27-overexpressing cells compared with LDs in control cells. Moreover, the lipid extracts of LDs from FSP27-overexpressing cells reconstituted large-droplet emulsions in vitro, implying that the lipid properties of LDs might affect the size of LDs. FSP27-overexpressing cells had more saturated fatty acids in the phospholipid monolayer of the LDs compared with control cells. To further investigate the effects of the degree of phospholipid unsaturation on the size of LDs, we synthesized artificial emulsions of a lipid mixed with distearoylphosphatidylcholine (DSPC, diC18:0-PC) and with dioleoylphosphatidylcholine (DOPC, diC18:1n-9-PC) and compared the sizes of the resulting LDs. The emulsions prepared from saturated PC had larger droplets than those prepared from unsaturated PC. Our results suggest that saturated fatty acid chains in phospholipid monolayers might establish the form and/or stability of large LDs. - Highlights: • The lipid extracts of larger LDs from FSP27 cells reconstructed large-droplet emulsions. • Isolated LDs from FSP27 cells had more saturated fatty acids in the phospholipid monolayer compared with the control. • Saturated fatty acids in the phospholipid monolayer are a factor in the formation of large emulsions.

  5. Targeted metabolomic profiling indicates structure-based perturbations in serum phospholipids in children with acetaminophen overdose

    Directory of Open Access Journals (Sweden)

    Sudeepa Bhattacharyya

    Full Text Available Phospholipids are an important class of lipids that act as building blocks of biological cell membranes and participate in a variety of vital cellular functions including cell signaling. Previous studies have reported alterations in phosphatidylcholine (PC and lysophosphatidylcholine (lysoPC metabolism in acetaminophen (APAP-treated animals or cell cultures. However, little is known about phospholipid perturbations in humans with APAP toxicity. In the current study, targeted metabolomic analysis of 180 different metabolites including 14 lysoPCs and 73 PCs was performed in serum samples from children and adolescents hospitalized for APAP overdose. Metabolite profiles in the overdose group were compared to those of healthy controls and hospitalized children receiving low dose APAP for treatment of pain or fever (therapeutic group. PCs and lysoPCs with very long chain fatty acids (VLCFAs were significantly decreased in the overdose group, while those with comparatively shorter chain lengths were increased in the overdose group compared to the therapeutic and control groups. All ether linked PCs were decreased in the overdose group compared to the controls. LysoPC-C26:1 was highly reduced in the overdose group and could discriminate between the overdose and control groups with 100% sensitivity and specificity. The PCs and lysoPCs with VLCFAs showed significant associations with changes in clinical indicators of drug metabolism (APAP protein adducts and liver injury (alanine aminotransferase, or ALT. Thus, a structure-dependent reduction in PCs and lysoPCs was observed in the APAP-overdose group, which may suggest a structure-activity relationship in inhibition of enzymes involved in phospholipid metabolism in APAP toxicity. Keywords: Metabolomics, Phospholipids, Acetaminophen, Hepatotoxicity, Drug

  6. Thermodynamic and real-space structural evidence of a 2D critical point in phospholipid monolayers

    DEFF Research Database (Denmark)

    Nielsen, Lars K.; Bjørnholm, Thomas; Mouritsen, Ole G.

    2007-01-01

    The two-dimensional phase diagram of phospholipid monolayers at air-water interfaces has been constructed from Langmuir compression isotherms. The coexistence region between the solid and fluid phases of the monolayer ends at the critical temperature of the transition. The small-scale lateral...... structure of the monolayers has been imaged by atomic force microscopy in the nm to mu m range at distinct points in the phase diagram. The lateral structure is immobilized by transferring the monolayer from an air-water interface to a solid mica support using Langmuir-Blodgett techniques. A transfer...

  7. Membrane fusion and exocytosis.

    Science.gov (United States)

    Jahn, R; Südhof, T C

    1999-01-01

    Membrane fusion involves the merger of two phospholipid bilayers in an aqueous environment. In artificial lipid bilayers, fusion proceeds by means of defined transition states, including hourglass-shaped intermediates in which the proximal leaflets of the fusing membranes are merged whereas the distal leaflets are separate (fusion stalk), followed by the reversible opening of small aqueous fusion pores. Fusion of biological membranes requires the action of specific fusion proteins. Best understood are the viral fusion proteins that are responsible for merging the viral with the host cell membrane during infection. These proteins undergo spontaneous and dramatic conformational changes upon activation. In the case of the paradigmatic fusion proteins of the influenza virus and of the human immunodeficiency virus, an amphiphilic fusion peptide is inserted into the target membrane. The protein then reorients itself, thus forcing the fusing membranes together and inducing lipid mixing. Fusion of intracellular membranes in eukaryotic cells involves several protein families including SNAREs, Rab proteins, and Sec1/Munc-18 related proteins (SM-proteins). SNAREs form a novel superfamily of small and mostly membrane-anchored proteins that share a common motif of about 60 amino acids (SNARE motif). SNAREs reversibly assemble into tightly packed helical bundles, the core complexes. Assembly is thought to pull the fusing membranes closely together, thus inducing fusion. SM-proteins comprise a family of soluble proteins that bind to certain types of SNAREs and prevent the formation of core complexes. Rab proteins are GTPases that undergo highly regulated GTP-GDP cycles. In their GTP form, they interact with specific proteins, the effector proteins. Recent evidence suggests that Rab proteins function in the initial membrane contact connecting the fusing membranes but are not involved in the fusion reaction itself.

  8. Modification of trout sperm membranes associated with activation and cryopreservation. Implications for fertilizing potential

    Science.gov (United States)

    Abstract We investigated the effects of two trout sperm activation solutions on sperm physiology and membrane organization prior to and following cryopreservation using flow cytometry and investigated their impact on in vitro fertility. Cryopreservation caused greater phospholipid disorder (high pl...

  9. PVC membrane, coated-wire, and carbon-paste ion-selective electrodes for potentiometric determination of galantamine hydrobromide in physiological fluids.

    Science.gov (United States)

    Abdel-Haleem, Fatehy M; Saad, Mohamed; Barhoum, Ahmed; Bechelany, Mikhael; Rizk, Mahmoud S

    2018-08-01

    We report on highly-sensitive ion-selective electrodes (ISEs) for potentiometric determining of galantamine hydrobromide (GB) in physiological fluids. Galantamine hydrobromide (GB) was selected for this study due to its previous medical importance for treating Alzheimer's disease. Three different types of ISEs were investigated: PVC membrane electrode (PVCE), carbon-paste electrode (CPE), and coated-wire electrode (CWE). In the construction of these electrodes, galantaminium-reineckate (GR) ion-pair was used as a sensing species for GB in solutions. The modified carbon-paste electrode (MCPE) was prepared using graphene oxide (MCPE-GO) and sodium tetrakis (trifluoromethyl) phenyl borate (MCPE-STFPB) as ion-exchanger. The potentiometric modified CPEs (MCPE-GO and MCPE-STFPB) show an improved performance in term of Nernstian slope, selectivity, response time, and response stability compared to the unmodified CPE. The prepared electrodes PVCE, CWE, CPE, MCPE-GO and MCPE-STFPB show Nernstian slopes of 59.9, 59.5, 58.1, 58.3 and 57.0 mV/conc. decade, and detection limits of 5.0 × 10 -6 , 6.3 × 10 -6 , 8.0 × 10 -6 , 6.0 × 10 -6 and 8.0 × 10 -6  mol L -1 , respectively. The prepared ISEs also show high selectivity against cations (i.e. Na + , K + , NH 4 + , Ca 2+ , Al 3+ , Fe 3+ ), amino acids (i.e. glycine, L-alanine alanine), and sugars (i.e. fructose, glucose, maltose, lactose). The prepared ISEs are applicable for determining GB in spiked serums, urines, and pharmaceutical preparations, using a standard addition and a direct potentiometric method. The fast response time (<10 s), long lifetime (1-5 weeks), reversibility and stability of the measured signals facilitate the application of these sensors for routine analysis of the real samples. Copyright © 2018 Elsevier B.V. All rights reserved.

  10. Analysis of Phospholipid Mixtures from Biological Tissues by Matrix-Assisted Laser Desorption and Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS): A Laboratory Experiment

    Science.gov (United States)

    Eibisch, Mandy; Fuchs, Beate; Schiller, Jurgen; Sub, Rosmarie; Teuber, Kristin

    2011-01-01

    Matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF MS) is increasingly used to investigate the phospholipid (PL) compositions of tissues and body fluids, often without previous separation of the total mixture into the individual PL classes. Therefore, the questions of whether all PL classes are detectable…

  11. An adaptive meshfree method for phase-field models of biomembranes. Part II: A Lagrangian approach for membranes in viscous fluids

    OpenAIRE

    Peco, C.; Rosolen, A.; Arroyo, M.

    2013-01-01

    We present a Lagrangian phase-field method to study the low Reynolds number dynamics of vesicles embedded in a viscous fluid. In contrast to previous approaches, where the field variables are the phase-field and the fluid velocity, here we exploit the fact that the phasefield tracks a material interface to reformulate the problem in terms of the Lagrangian motion of a background medium, containing both the biomembrane and the fluid. We discretize the equations in space with maximum-entr...

  12. Phospholipid fatty acid and phospholipid etherlipid fingerprints approach to describe complex soil microbial community under impact of cattle husbandry

    Czech Academy of Sciences Publication Activity Database

    Elhottová, Dana; Němcová, Anna; Gattinger, A.

    2007-01-01

    Roč. 48, - (2007), s. 73 ISSN 0009-0646. [Kongres Československé společnosti mikrobiologické /24./. 02.10.2007-05.10.2007, Liberec] Institutional research plan: CEZ:AV0Z60660521 Keywords : phospholipid fatty acid * phospholipid etherlipid fingerprints * cattle husbandry Subject RIV: EH - Ecology, Behaviour

  13. Acoustic concentration of particles in fluid flow

    Science.gov (United States)

    Ward, Michael D.; Kaduchak, Gregory

    2010-11-23

    An apparatus for acoustic concentration of particles in a fluid flow includes a substantially acoustically transparent membrane and a vibration generator that define a fluid flow path therebetween. The fluid flow path is in fluid communication with a fluid source and a fluid outlet and the vibration generator is disposed adjacent the fluid flow path and is capable of producing an acoustic field in the fluid flow path. The acoustic field produces at least one pressure minima in the fluid flow path at a predetermined location within the fluid flow path and forces predetermined particles in the fluid flow path to the at least one pressure minima.

  14. Acoustic concentration of particles in fluid flow

    Science.gov (United States)

    Ward, Michael W.; Kaduchak, Gregory

    2017-08-15

    Disclosed herein is a acoustic concentration of particles in a fluid flow that includes a substantially acoustically transparent membrane and a vibration generator that define a fluid flow path therebetween. The fluid flow path is in fluid communication with a fluid source and a fluid outlet and the vibration generator is disposed adjacent the fluid flow path and is capable of producing an acoustic field in the fluid flow path. The acoustic field produces at least one pressure minima in the fluid flow path at a predetermined location within the fluid flow path and forces predetermined particles in the fluid flow path to the at least one pressure minima.

  15. Mechanism of enhanced oral absorption of morin by phospholipid complex based self-nanoemulsifying drug delivery system.

    Science.gov (United States)

    Zhang, Jinjie; Li, Jianbo; Ju, Yuan; Fu, Yao; Gong, Tao; Zhang, Zhirong

    2015-02-02

    Phospholipid complex (PLC) based self-nanoemulsifying drug delivery system (PLC-SNEDDS) has been developed for efficient delivery of drugs with poor solubility and low permeability. In the present study, a BCS class IV drug and a P-glycoprotein (P-gp) substrate, morin, was selected as the model drug to elucidate the oral absorption mechanism of PLC-SNEDDS. PLC-SNEDDS was superior to PLC in protecting morin from degradation by intestinal enzymes in vitro. In situ perfusion study showed increased intestinal permeability by PLC was duodenum-specific. In contrast, PLC-SNEDDS increased morin permeability in all intestinal segments and induced a change in the main absorption site of morin from colon to ileum. Moreover, ileum conducted the lymphatic transport of PLC-SNEDDS, which was proven by microscopic intestinal visualization of Nile red labeled PLC-SNEDDS and lymph fluids in vivo. Low cytotoxicity and increased Caco-2 cell uptake suggested a safe and efficient delivery of PLC-SNEDDS. The increased membrane fluidity and disrupted actin filaments were closely associated with the increased cell uptake of PLC-SNEDDS. PLC-SNEDDS could be internalized into enterocytes as an intact form in a cholesterol-dependent manner via clathrin-mediated endocytosis and macropinocytosis. The enhanced oral absorption of morin was attributed to the P-gp inhibition by Cremophor RH and the intact internalization of M-PLC-SNEDDS into Caco-2 cells bypassing P-gp recognition. Our findings thus provide new insights into the development of novel nanoemulsions for poorly absorbed drugs.

  16. A nonpolar, nonamphiphilic molecule can accelerate adsorption of phospholipids and lower their surface tension at the air/water interface.

    Science.gov (United States)

    Nguyen, Phuc Nghia; Trinh Dang, Thuan Thao; Waton, Gilles; Vandamme, Thierry; Krafft, Marie Pierre

    2011-10-04

    The adsorption dynamics of a series of phospholipids (PLs) at the interface between an aqueous solution or dispersion of the PL and a gas phase containing the nonpolar, nonamphiphilic linear perfluorocarbon perfluorohexane (PFH) was studied by bubble profile analysis tensiometry. The PLs investigated were dioctanoylphosphatidylcholine (DiC(8)-PC), dilaurylphosphatidylcholine, dimyristoylphosphatidylcholine, and dipalmitoylphosphatidylcholine. The gas phase consisted of air or air saturated with PFH. The perfluorocarbon gas was found to have an unexpected, strong effect on both the adsorption rate and the equilibrium interfacial tension (γ(eq)) of the PLs. First, for all of the PLs, and at all concentrations investigated, the γ(eq) values were significantly lower (by up to 10 mN m(-1)) when PFH was present in the gas phase. The efficacy of PFH in decreasing γ(eq) depends on the ability of PLs to form micelles or vesicles in water. For vesicles, it also depends on the gel or fluid state of the membranes. Second, the adsorption rates of all the PLs at the interface (as assessed by the time required for the initial interfacial tension to be reduced by 30%) are significantly accelerated (by up to fivefold) by the presence of PFH for the lower PL concentrations. Both the surface-tension reducing effect and the adsorption rate increasing effect establish that PFH has a strong interaction with the PL monolayer and acts as a cosurfactant at the interface, despite the absence of any amphiphilic character. Fitting the adsorption profiles of DiC(8)-PC at the PFH-saturated air/aqueous solution interface with the modified Frumkin model indicated that the PFH molecule lay horizontally at the interface. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Food enrichment with marine phospholipid emulsions

    DEFF Research Database (Denmark)

    Lu, Henna Fung Sieng; Nielsen, Nina Skall; Baron, Caroline P.

    marine PL emulsions with and without addition of fish oil. The oxidative stability of marine PL emulsions was significantly influenced by the chemical composition of marine PL used for emulsions preparation. For instance, emulsions with good oxidative stability could be obtained when using raw materials...... with high purity, low fish oil content and high PL, cholesterol and α-tocopherol content. In addition, non-enzymatic browning reactions may also affect the oxidative stability of the marine PL emulsion. These reactions included Strecker degradation and pyrrolization, and their occurrence were due......Many studies have shown that marine phospholipids (PL) provide more advantages than fish oil. They seem to have better bioavailability, better resistance towards oxidation and higher content of eicosapentaenoic acids and docosahexaenoic acids than fish oil, which essentially contains triglycerides...

  18. Spontaneous transfer of gangliotetraosylceramide between phospholipid vesicles

    International Nuclear Information System (INIS)

    Brown, R.E.; Sugar, I.P.; Thompson, T.E.

    1985-01-01

    The transfer kinetics of the neutral glycosphingolipid gangliotetraosylceramide (asialo-GM1) were investigated by monitoring tritiated asialo-GM1 movement from donor to acceptor vesicles. Two different methods were employed to separate donor and acceptor vesicles at desired time intervals. In one method, a negative charge was imparted to dipalmitoylphosphatidylcholine donor vesicles by including 10 mol% dipalmitoylphosphatidic acid. Donors were separated from neutral dipalmitoylphosphatidylcholine acceptor vesicles by ion-exchange chromatography. In the other method, small, unilamellar donor vesicles and large, unilamellar acceptor vesicles were coincubated at 45 degrees C and then separated at desired time intervals by molecular sieve chromatography. The majority of asialo-GM1 transfer to acceptor vesicles occurred as a slow first-order process with a half-time of about 24 days assuming that the relative concentration of asialo-GM1 in the phospholipid matrix was identical in each half of the donor bilayer and that no glycolipid flip-flop occurred. Asialo-GM1 net transfer was calculated relative to that of [ 14 C]cholesteryl oleate, which served as a nontransferable marker in the donor vesicles. A nearly identical transfer half-time was obtained when the phospholipid matrix was changed from dipalmitoylphosphatidylcholine to palmitoyloleoylphosphatidylcholine. Varying the acceptor vesicle concentration did not significantly alter the asialo-GM1 transfer half-time. This result is consistent with a transfer mechanism involving diffusion of glycolipid through the aqueous phase rather than movement of glycolipid following formation of collisional complexes between donor and acceptor vesicles. (Abstract Truncated)

  19. Progress in surface and membrane science

    CERN Document Server

    Cadenhead, D A

    1976-01-01

    Progress in Surface and Membrane Science, Volume 10 covers the advances in surface and membrane science. The book discusses the selective changes of cellular particles influencing sedimentation properties; and the rotating disk and ring-disk electrodes in investigations of surface phenomena at the metal-electrolyte interface. The text also describes the membrane potential of phospholipid bilayer and biological membranes; the adsorption of surfactant monolayers at gas/liquid and liquid/liquid interfaces; and the enzymes immobilized on glass. Chemists and people involved in electrochemistry will

  20. Progress in surface and membrane science

    CERN Document Server

    Danielli, J F; Cadenhead, D A

    1972-01-01

    Progress in Surface and Membrane Science, Volume 5 covers the developments in the study of surface and membrane science. The book discusses the Mössbauer effect in surface science; the surface functional groups on carbon and silica; and the wetting phenomena pertaining to adhesion. The text also describes the physical state of phospholipids and cholesterol in monolayers, bilayers, and membranes; the characteristics of heterocoagulation; and the effects of calcium on excitable membranes and neurotransmitter action. Chemists, physiologists, biophysicists, and civil engineers will find the book i

  1. The effect of X-irradiation on membrane lipids of lymphosarcoma cells in vivo and in vitro

    NARCIS (Netherlands)

    Fonck, K; Scherphof, GL; Konings, AWT

    1982-01-01

    Phospholipids of the membranes of spleen lymphosarcoma cells were radioactively labelled with the radioresistant fatty acid palmitic acid (16:0) and the radiosensitive fatty acid arachidonic acid (20:4). The effect of irradiation on the specific radioactivity of the phospholipids was studied. For

  2. Phospholipids in Milk Fat: Composition, Biological and Technological Significance, and Analytical Strategies

    Directory of Open Access Journals (Sweden)

    Giovanna Contarini

    2013-01-01

    Full Text Available Glycerophospholipids and sphingolipids are quantitatively the most important phospholipids (PLs in milk. They are located on the milk fat globule membrane (MFGM and in other membranous material of the skim milk phase. They include principally phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol and phosphatidylserine, while sphingomyelin is the dominant species of sphingolipids There is considerable evidence that PLs have beneficial health effects, such as regulation of the inflammatory reactions, chemopreventive and chemotherapeutic activity on some types of cancer, and inhibition of the cholesterol absorption. PLs show good emulsifying properties and can be used as a delivery system for liposoluble constituents. Due to the amphiphilic characteristics of these molecules, their extraction, separation and detection are critical points in the analytical approach. The extraction by using chloroform and methanol, followed by the determination by high pressure liquid chromatography (HPLC, coupled with evaporative light scattering (ELSD or mass detector (MS, are the most applied procedures for the PL evaluation. More recently, nuclear magnetic resonance spectrometry (NMR was also used, but despite it demonstrating high sensitivity, it requires more studies to obtain accurate results. This review is focused on milk fat phospholipids; their composition, biological activity, technological properties, and significance in the structure of milk fat. Different analytical methodologies are also discussed.

  3. Structural basis of control of inward rectifier Kir2 channel gating by bulk anionic phospholipids.

    Science.gov (United States)

    Lee, Sun-Joo; Ren, Feifei; Zangerl-Plessl, Eva-Maria; Heyman, Sarah; Stary-Weinzinger, Anna; Yuan, Peng; Nichols, Colin G

    2016-09-01

    Inward rectifier potassium (Kir) channel activity is controlled by plasma membrane lipids. Phosphatidylinositol-4,5-bisphosphate (PIP2) binding to a primary site is required for opening of classic inward rectifier Kir2.1 and Kir2.2 channels, but interaction of bulk anionic phospholipid (PL(-)) with a distinct second site is required for high PIP2 sensitivity. Here we show that introduction of a lipid-partitioning tryptophan at the second site (K62W) generates high PIP2 sensitivity, even in the absence of PL(-) Furthermore, high-resolution x-ray crystal structures of Kir2.2[K62W], with or without added PIP2 (2.8- and 2.0-Å resolution, respectively), reveal tight tethering of the C-terminal domain (CTD) to the transmembrane domain (TMD) in each condition. Our results suggest a refined model for phospholipid gating in which PL(-) binding at the second site pulls the CTD toward the membrane, inducing the formation of the high-affinity primary PIP2 site and explaining the positive allostery between PL(-) binding and PIP2 sensitivity. © 2016 Lee et al.

  4. Hydrophobic nanoparticles promote lamellar to inverted hexagonal transition in phospholipid mesophases.

    Science.gov (United States)

    Bulpett, Jennifer M; Snow, Tim; Quignon, Benoit; Beddoes, Charlotte M; Tang, T-Y D; Mann, Stephen; Shebanova, Olga; Pizzey, Claire L; Terrill, Nicholas J; Davis, Sean A; Briscoe, Wuge H

    2015-12-07

    This study focuses on how the mesophase transition behaviour of the phospholipid dioleoyl phosphatidylethanolamine (DOPE) is altered by the presence of 10 nm hydrophobic and 14 nm hydrophilic silica nanoparticles (NPs) at different concentrations. The lamellar to inverted hexagonal phase transition (Lα-HII) of phospholipids is energetically analogous to the membrane fusion process, therefore understanding the Lα-HII transition with nanoparticulate additives is relevant to how membrane fusion may be affected by these additives, in this case the silica NPs. The overriding observation is that the HII/Lα boundaries in the DOPE p-T phase diagram were shifted by the presence of NPs: the hydrophobic NPs enlarged the HII phase region and thus encouraged the inverted hexagonal (HII) phase to occur at lower temperatures, whilst hydrophilic NPs appeared to stabilise the Lα phase region. This effect was also NP-concentration dependent, with a more pronounced effect for higher concentration of the hydrophobic NPs, but the trend was less clear cut for the hydrophilic NPs. There was no evidence that the NPs were intercalated into the mesophases, and as such it was likely that they might have undergone microphase separation and resided at the mesophase domain boundaries. Whilst the loci and exact roles of the NPs invite further investigation, we tentatively discuss these results in terms of both the surface chemistry of the NPs and the effect of their curvature on the elastic bending energy considerations during the mesophase transition.

  5. Mesoscopic models of biological membranes

    DEFF Research Database (Denmark)

    Venturoli, M.; Sperotto, Maria Maddalena; Kranenburg, M.

    2006-01-01

    Phospholipids are the main components of biological membranes and dissolved in water these molecules self-assemble into closed structures, of which bilayers are the most relevant from a biological point of view. Lipid bilayers are often used, both in experimental and by theoretical investigations...... to coarse grain a biological membrane. The conclusion of this comparison is that there can be many valid different strategies, but that the results obtained by the various mesoscopic models are surprisingly consistent. A second objective of this review is to illustrate how mesoscopic models can be used...

  6. Composition, structure and properties of POPC–triolein mixtures. Evidence of triglyceride domains in phospholipid bilayers

    DEFF Research Database (Denmark)

    Duelund, Lars; Jensen, Grethe Vestergaard; Hannibal-Bach, Hans Kristian

    2013-01-01

    We have in this study investigated the composition, structure and spectroscopical properties of multilamellar vesicles composed of a phospholipid, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), and up to 10mol% of triolein (TO), a triglyceride. We found in agreement with previous results...... as vesicular structures containing entrapped water. Bilayer structure of the membranes was supported by small angle X-ray scattering that showed the membranes to form a lamellar phase. Fluorescence spectroscopy with the polarity sensitive dye Nile red revealed, that the LF samples with more than 5mol......% TO contained pure TO domains. These observations are consistent with an earlier MD simulation study by us and our co-workers suggesting triglycerides to be located in lens shaped, blister-like domains between the two lipid bilayer leaflets (Khandelia et al. (2010) [26])....

  7. Administration of phospholipide hepatoprotective drug Phosphogliv in patients with psoriatic arthritis (preliminary results

    Directory of Open Access Journals (Sweden)

    T. V. Korotaeva

    2004-01-01

    Full Text Available Considering membrane-reparative properties of a new phospholipid hepatoprotector Phosphogliv (FG its therapeutic efficacy was assessed in 9 pts with psoriatic arthritis (PA accompanied by prominent disturbances of blood rheology. FG was given 0,6 g a day during 3 months. Significant decrease of erythrocyte aggregation resulting in increase of erythrocyte aggregation formation time and diminishment of their hydrodynamic resistance without changes of whole blood general caisson viscosity was achieved. Significant improvement of Richie index, tender joint count and pt assessment was noted. The results prove availability of PG administration in PA therapy and possibility of enlargement PG application area owing to membrane-reparative properties of contained in it polyunsaturated phosphatidilcholin in combination with immunomodulating and anti-inflammatory action of glycyrrhizinic acid.

  8. Fusion between fluid liposomes and intact bacteria: study of driving parameters and in vitro bactericidal efficacy

    Directory of Open Access Journals (Sweden)

    Wang Z

    2016-08-01

    Full Text Available Zhao Wang,1,2* Yufan Ma,1,3,4* Hayssam Khalil,1 Rutao Wang,1–3 Tingli Lu,1 Wen Zhao,1 Yang Zhang,3 Jamin Chen,1,2 Tao Chen,1–3  1Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi, 2Shaanxi Liposome Research Center, Xi'an, Shaanxi, 3Xi'an Libang Pharmaceuticals Co, Ltd, Xi'an, 4School of Medicine, Xi'an Jiaotong University, Xi'an, People's Republic of China *These authors contributed equally to this work. Background: Pseudomonas aeruginosa represents a good model of antibiotic resistance. These organisms have an outer membrane with a low level of permeability to drugs that is often combined with multidrug efflux pumps, enzymatic inactivation of the drug, or alteration of its molecular target. The acute and growing problem of antibiotic resistance of bacteria to conventional antibiotics made it imperative to develop new liposome formulations for antibiotics, and investigate the fusion between liposome and bacterium. Methods: In this study, the factors involved in fluid liposome interaction with bacteria have been investigated. We also demonstrated a mechanism of fusion between liposomes (1,2-dipalmitoyl-sn-glycero-3-phosphocholine [DPPC]/dimyristoylphosphatidylglycerol [DMPG] 9:1, mol/mol in a fluid state, and intact bacterial cells, by lipid mixing assay. Results: The observed fusion process is shown to be mainly dependent on several key factors. Perturbation of liposome fluidity by addition of cholesterol dramatically decreased the degree of fusion with P. aeruginosa from 44% to 5%. It was observed that fusion between fluid liposomes and bacteria and also the bactericidal activities were strongly dependent upon the properties of the bacteria themselves. The level of fusion detected when fluid liposomes were mixed with Escherichia coli (66% or P. aeruginosa (44% seems to be correlated to their outer membrane phosphatidylethanolamine (PE phospholipids

  9. Metabolism of fatty acids in rat brain in microsomal membranes

    International Nuclear Information System (INIS)

    Aeberhard, E.E.; Gan-Elepano, M.; Mead, J.F.

    1980-01-01

    Using a technique in which substrate fatty acids are incorporated into microsomal membranes followd by comparison of their rates of desaturation or elongation with those of exogenous added fatty acids it has been found that the desaturation rate is more rapid for the membrane-bound substrate than for the added fatty acid. Moreover, the product of the membrane-bound substrate is incorporated into membrane phospholipid whereas the product of the exogenous substrate is found in di- and triacyl glycerols and in free fatty acids as well. These and other findings point to a normal sequence of reaction of membrane liqids with membrane-bound substrates involving transfer of fatty acid from phospholipid to the coupled enzyme systems without ready equilibration with the free fatty acid pool

  10. Timing of Histologic Progression from Chorio-Deciduitis to Chorio-Deciduo-Amnionitis in the Setting of Preterm Labor and Preterm Premature Rupture of Membranes with Sterile Amniotic Fluid.

    Science.gov (United States)

    Park, Chan-Wook; Park, Joong Shin; Norwitz, Errol R; Moon, Kyung Chul; Jun, Jong Kwan; Yoon, Bo Hyun

    2015-01-01

    Histologic chorio-deciduitis and chorio-deciduo-amnionitis (amnionitis) in extra-placental membranes are known to represent the early and advanced stages of ascending intra-uterine infection. However, there are no data in humans about the time required for chorio-deciduitis to develop and for chorio-deciduitis without amnionitis to progress to chorio-deciduitis with amnionitis, and the effect of prolongation of pregnancy on the development of chorio-deciduitis and amnionitis in patients with preterm labor and intact membranes (PTL) and preterm premature rupture of membranes (preterm-PROM). We examined these issues in this study. The study population consisted of 289 women who delivered preterm (133 cases with PTL, and 156 cases with preterm-PROM) and who had sterile amniotic fluid (AF) defined as a negative AF culture and the absence of inflammation as evidenced by a matrix metalloproteinase-8 (MMP-8) level membranes (i.e., inflammation-free extra-placental membranes, choroi-deciduitis only, and chorio-deciduitis with amnionitis) in patients with PTL and preterm-PROM. Amniocentesis-to-delivery interval was longer in cases of chorio-deciduitis with amnionitis than in cases of chorio-deciduitis only in both PTL (median [interquartile-range (IQR)]; 645.4 [319.5] vs. 113.9 [526.9] hours; P = 0.005) and preterm-PROM (131.3 [135.4] vs. 95.2 [140.5] hours; Pmembranes. Moreover, prolongation of pregnancy is an independent predictor of the development of both chorio-deciduitis and amnionitis in cases of PTL with sterile AF.

  11. Phospholipid transfer protein activity and incident type 2 diabetes mellitus

    NARCIS (Netherlands)

    Abbasi, Ali; Dallinga-Thie, Geesje M.; Dullaart, Robin P. F.

    2015-01-01

    Background: The plasma activity of phospholipid transfer protein (PLTP), which has multifaceted functions in lipoprotein metabolism and in inflammatory responses, is elevated in insulin resistant conditions. We determined the association of plasma PLTP activity with incident type 2 diabetes mellitus

  12. Novel Antimicrobial Peptide Dendrimers with Amphiphilic Surface and Their Interactions with Phospholipids — Insights from Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    Paulina Zielinska

    2013-06-01

    Full Text Available A series of new peptide dendrimers with amphiphilic surface, designed around a dendronized ornithine (Orn core were synthesized and characterized by ESI-MS, 1H-, 13C- NMR, and CD spectrometry. An improved antimicrobial potency against S. aureus and E. coli was detected as a result of an increased charge, higher branching and variable lipophilicity of the residues located at the C-terminus. Minimal inhibitory concentration (MIC values indicated that the selected dendrimers were not sensitive to the physiological concentration of Na+ and K+ ions (100 mM, but expressed reduced potency at 10 mM concentration of Mg2+ and Ca2+ ions. Circular dichroism (CD curves measured under various conditions revealed structure and solvent-dependent curve evolution. ESI-MS studies of gas-phase interactions between selected dendrimers and both anionic (DMPG and neutral (DMPC phospholipids revealed the presence of variously charged dendrimer/phospholipid aggregates with 1:1 to 1:5 stoichiometry. The collision-induced fragmentation (CID of the most abundant [dendrimer/phospholipid]2+ ions of the 1:1 stoichiometry demonstrated that the studied dendrimers formed stronger complexes with anionic DMPG. Both phospholipids have higher affinity towards dendrimers with a more compact structure. Higher differences in CID energy necessary for dissociation of 50% of the complex formed by dendrimers with DMPG vs. DMPC (DCID50 correlate with a lower hemotoxicity. Mass spectrometry results suggest that for a particular group of compounds the DCID50 might be one of the important factors explaining selectivity of antimicrobial peptides and their branched analogs targeting the bacterial membrane. Both circular dichroism and mass spectrometry studies demonstrated that dendrimers of Nα- and Nε-series possess a different conformation in solution and different affinity to model phospholipids, what might influence their specific microbicidal mechanism.

  13. Regional distribution of phospholipids in porcine vitreous humor.

    Science.gov (United States)

    Schnepf, Abigail; Yappert, Marta Cecilia; Borchman, Douglas

    2017-07-01

    This project explores the regional phospholipid distribution in porcine vitreous humor, retina, and lens. Matrix-assisted laser desorption mass spectrometry has been used previously to image lipids, proteins, and other metabolites in retinas and lenses. However, the regional composition of phospholipids in vitreous humors is not known. To address this issue, we have applied this mass spectral method to explore the regional phospholipid distribution in porcine vitreous humor both ex-situ and in-vitro. To establish the possible source(s) of phospholipids in the vitreous humor, compositional studies of the lens and retina were also pursued. Due to the overall low levels of phospholipids in vitreous humor, it was necessary to optimize the experimental approaches for ex-situ and in-vitro studies. The sensitivity observed in the spectra of methanol extracts from the lens and retina was higher than that for methanol:chloroform extracts, but the compositional trends were the same. A fourfold improvement in sensitivity was observed in the analysis of vitreous humor extracts obtained with the Bligh and Dyer protocol relative to the other two extraction methods. For ex-situ studies, the 'stamp method' with para-nitroaniline as the matrix was chosen. Throughout the vitreous humor, phosphatidylcholines were the most abundant phospholipids. In-vitro results showed higher relative levels of phospholipids compared to the 'stamp' method. However, more details in the regional phospholipid distribution were provided by the ex-situ approach. Both in-vitro and ex-situ results indicated higher levels of phospholipids in the posterior vitreous region, followed by the anterior and central regions. The posterior region contained more unsaturated species whereas more saturated phospholipids were detected in the anterior region. The observed trends suggest that the phospholipids detected in the posterior vitreous humor migrate from the retina and associated vasculature while those present in

  14. The Physical Properties of Ceramides in Membranes.

    Science.gov (United States)

    Alonso, Alicia; Goñi, Félix M

    2018-05-20

    Ceramides are sphingolipids containing a sphingosine or a related base, to which a fatty acid is linked through an amide bond. When incorporated into a lipid bilayer, ceramides exhibit a number of properties not shared by almost any other membrane lipid: Ceramides ( a) are extremely hydrophobic and thus cannot exist in suspension in aqueous media; ( b) increase the molecular order (rigidity) of phospholipids in membranes; ( c) give rise to lateral phase separation and domain formation in phospholipid bilayers; ( d) possess a marked intrinsic negative curvature that facilitates formation of inverted hexagonal phases; ( e) make bilayers and cell membranes permeable to small and large (i.e., protein-size) solutes; and ( f) promote transmembrane (flip-flop) lipid motion. Unfortunately, there is hardly any link between the physical studies reviewed here and the mass of biological and clinical studies on the effects of ceramides in health and disease.

  15. Exit-strategies - smart ways to release phospholipid vesicle cargo

    OpenAIRE

    Mellal Denia; Zumbuehl Andreas

    2014-01-01

    This highlight describes recent trends in fundamental phospholipid research towards possible future drug delivery technology. In particular it focuses on synthetic phospholipids and their vesicular constructs and describes selected “smart” ways to release cargo from liposomes. Various chemical and physical release triggers are discussed such as temperature changes, application of ultrasound, enzyme degradation, changes in pH, redox reactions, photochemical reactions, as well as the effects of...

  16. Fluid Shifts

    Science.gov (United States)

    Stenger, M. B.; Hargens, A. R.; Dulchavsky, S. A.; Arbeille, P.; Danielson, R. W.; Ebert, D. J.; Garcia, K. M.; Johnston, S. L.; Laurie, S. S.; Lee, S. M. C.; hide

    2017-01-01

    pulsatility); (5) ocular measures (optical coherence tomography; intraocular pressure; 2-dimensional ultrasound including optic nerve sheath diameter, globe flattening, and retina-choroid thickness; Doppler ultrasound of ophthalmic and retinal arteries and veins); (6) cardiac variables by ultrasound (inferior vena cava, tricuspid flow and tissue Doppler, pulmonic valve, stroke volume, right heart dimensions and function, four-chamber views); and (7) ICP measures (tympanic membrane displacement, otoacoustic emissions). Pre- and post-flight, acute head-down tilt will induce cephalad fluid shifts, whereas lower body negative pressure will oppose these shifts. Controlled Mueller maneuvers will manipulate cardiovascular variables. Through interventions applied before, during, and after flight, we intend to fully evaluate the relationship between fluid shifts and the VIIP syndrome. Discussion. Ten subjects have consented to participate in this experiment, including the recent One-Year Mission crewmembers, who have recently completed R plus180 testing; all other subjects have completed pre-flight testing. Preliminary results from the One-Year Mission crewmembers will be presented, including measures of ocular structure and function, vascular dimensions, fluid distribution, and non-invasive estimates of intracranial pressure.

  17. Annexin A4 and A6 induce membrane curvature and constriction during cell membrane repair

    DEFF Research Database (Denmark)

    Boye, Theresa Louise; Maeda, Kenji; Pezeshkian, Weria

    2017-01-01

    Efficient cell membrane repair mechanisms are essential for maintaining membrane integrity and thus for cell life. Here we show that the Ca2+- and phospholipid-binding proteins annexin A4 and A6 are involved in plasma membrane repair and needed for rapid closure of micron-size holes. We demonstrate...... that annexin A4 binds to artificial membranes and generates curvature force initiated from free edges, whereas annexin A6 induces constriction force. In cells, plasma membrane injury and Ca2+ influx recruit annexin A4 to the vicinity of membrane wound edges where its homo-trimerization leads to membrane...... that induction of curvature force around wound edges is an early key event in cell membrane repair....

  18. Phospholipase D catalyzes phospholipid metabolism in chemotactic peptide-stimulated HL-60 granulocytes

    International Nuclear Information System (INIS)

    Pai, J.K.; Siegel, M.I.; Egan, R.W.; Billah, M.M.

    1988-01-01

    There exists circumstantial evidence for activation of phospholipase D (PLD) in intact cells. However, because of the complexity of phospholipid remodeling processes, it is essential to distinguish PLD clearly from other phospholipases and phospholipid remodeling enzymes. Therefore, to establish unequivocally PLD activity in dimethyl sulfoxide-differentiated HL-60 granulocytes, to demonstrate the relative contribution of PLD to phospholipid turnover, and to validate the hypothesis that the formation of phosphatidylethanol is an expression of PLD-catalyzed transphosphatidylation, we have developed methodologies to label HL-60 granulocytes in 1-O-alkyl-2-acyl-sn-glycero-3-phosphocholine (alkyl-PC) with 32P without labeling cellular ATP. These methodologies involve (a) synthesis of alkyl-lysoPC containing 32P by a combination of enzymatic and chemical procedures and (b) incubation of HL-60 granulocytes with this alkyl-[32P] lysoPC which enters the cell and becomes acylated into membrane-associated alkyl-[32P]PC. Upon stimulation of these 32P-labeled cells with the chemotactic peptide, N-formyl-Met-Leu-Phe (fMLP), alkyl-[32P]phosphatidic acid (alkyl-[32P]PA) is formed rapidly. Because, under these conditions, cellular ATP has not been labeled with 32P, alkyl-[32P]PA must be formed via PLD-catalyzed hydrolysis of alkyl-[32P]PC at the terminal phosphodiester bond. This result conclusively demonstrates fMLP-induced activation of PLD in HL-60 granulocytes. These 32P-labeled HL-60 granulocytes have also been stimulated in the presence of ethanol to produce alkyl-[32P]phosphatidylethanol (alkyl-[32P]PEt). Formation of alkyl-[32P]PEt parallels that of alkyl-[32P]PA with respect to time course, fMLP concentration, inhibition by a specific fMLP antagonist (t-butoxycarbonyl-Met-Leu-Phe), and Ca2+ concentration

  19. Solid-state NMR paramagnetic relaxation enhancement immersion depth studies in phospholipid bilayers

    KAUST Repository

    Chu, Shidong

    2010-11-01

    A new approach for determining the membrane immersion depth of a spin-labeled probe has been developed using paramagnetic relaxation enhancement (PRE) in solid-state NMR spectroscopy. A DOXYL spin label was placed at different sites of 1-palmitoyl-2-stearoyl-sn-glycero-3-phosphocholine (PSPC) phospholipid bilayers as paramagnetic moieties and the resulting enhancements of the longitudinal relaxation (T1) times of 31P nuclei on the surface of the bilayers were measured by a standard inversion recovery pulse sequence. The 31P NMR spin-lattice relaxation times decrease steadily as the DOXYL spin label moves closer to the surface as well as the concentration of the spin-labeled lipids increase. The enhanced relaxation vs. the position and concentration of spin-labels indicate that PRE induced by the DOXYL spin label are significant to determine longer distances over the whole range of the membrane depths. When these data were combined with estimated correlation times τc, the r-6-weighted, time-averaged distances between the spin-labels and the 31P nuclei on the membrane surface were estimated. The application of using this solid-state NMR PRE approach coupled with site-directed spin labeling (SDSL) may be a powerful method for measuring membrane protein immersion depth. © 2010 Elsevier Inc. All rights reserved.

  20. Binding of Neurotransmitters to Lipid Membranes

    DEFF Research Database (Denmark)

    Peters, Günther H.J.; Werge, Mikkel; Elf-Lind, Maria Northved

    2014-01-01

    / acetylated g-aminobutyrate (GABAneu) with a dipalmitoylphosphatidylcholine (DPPC) bilayer. This study was motivated by recent research results that suggested that neural transmission may also be affected by nonspecific interactions of NTs with the lipid matrix of the synaptic membrane. Our results revealed...... backbone of the phospholipids. It is surprising that hydrophilic solutes can deeply penetrate into the membrane pointing to the fact that membrane affinity is governed by specific interactions. Our MD simulations identified the salt-bridge between the primary amine of NTs and the lipid phosphate group...

  1. Hyaluronan and phospholipid association in biolubrication

    DEFF Research Database (Denmark)

    Wang, Min; Liu, Chao; Thormann, Esben

    2013-01-01

    It is becoming increasingly clear that the outstanding lubrication of synovial joints is achieved by a sophisticated hierarchical structure of cartilage combined with synergistic actions of surface-active components present in the synovial fluid. In this work we focus on the association of two co...

  2. Surface functionalization of a polymeric lipid bilayer for coupling a model biological membrane with molecules, cells, and microstructures.

    Science.gov (United States)

    Morigaki, Kenichi; Mizutani, Kazuyuki; Saito, Makoto; Okazaki, Takashi; Nakajima, Yoshihiro; Tatsu, Yoshiro; Imaishi, Hiromasa

    2013-02-26

    We describe a stable and functional model biological membrane based on a polymerized lipid bilayer with a chemically modified surface. A polymerized lipid bilayer was formed from a mixture of two diacetylene-containing phospholipids, 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine (DiynePC) and 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphoethanolamine (DiynePE). DiynePC formed a stable bilayer structure, whereas the ethanolamine headgroup of DiynePE enabled functional molecules to be grafted onto the membrane surface. Copolymerization of DiynePC and DiynePE resulted in a robust bilayer. Functionalization of the polymeric bilayer provided a route to a robust and biomimetic surface that can be linked with biomolecules, cells, and three-dimensional (3D) microstructures. Biotin and peptides were grafted onto the polymeric bilayer for attaching streptavidin and cultured mammalian cells by molecular recognition, respectively. Nonspecific adsorption of proteins and cells on polymeric bilayers was minimum. DiynePE was also used to attach a microstructure made of an elastomer (polydimethylsiloxan: PDMS) onto the membrane, forming a confined aqueous solution between the two surfaces. The microcompartment enabled us to assay the activity of a membrane-bound enzyme (cyochrome P450). Natural (fluid) lipid bilayers were incorporated together with membrane-bound proteins by lithographically polymerizing DiynePC/DiynePE bilayers. The hybrid membrane of functionalized polymeric bilayers and fluid bilayers offers a novel platform for a wide range of biomedical applications including biosensor, bioassay, cell culture, and cell-based assay.

  3. Fluid migration through geo-membrane seams and through the interface between geo-membrane and geo-synthetic clay liner; Contribution a l'etude des transferts de masse au niveau des joints de geomembrane et a l'interface entre geomembrane et geosynthetique bentonitique

    Energy Technology Data Exchange (ETDEWEB)

    Barroso, M

    2005-03-15

    Composite liners are used to limit the contamination migration from landfills. Their successful performance is closely related with the geo-membrane as it provides the primary barrier to diffusive and advective transport of contaminants. Critical issues on the performance of the geo-membranes are the seams between geo-membrane panels and the inevitable defects resulting, for instance, from inadequate installation activities. In landfills, where high density polyethylene geo-membranes are usually used, seams are typically made by the thermal-hot dual wedge method. A literature review on quality control of the seams showed that, in situ, fluid-tightness of seams is evaluated in qualitative terms (pass/failure criteria), despite their importance to ensure appropriate performance of the geo-membranes as barriers. In addition, a synthesis of studies on geo-membrane defects indicated that defects varying in density from 0.7 to 15.3 per hectare can be found in landfills. Defects represent preferential flow paths for leachate. Various authors have developed analytical solutions and empirical equations for predicting the flow rate through composite liners due to defects in the geo-membrane. The validity of these methods for composite liners comprising a geo-membrane over a geo-synthetic clay liner (GCL) over a compacted clay liner (CCL) has never been studied from an experimental point of view. To address the problem of fluid migration through the geo-membrane seams, an attempt is made to provide a test method, herein termed as 'gas permeation pouch test', for assessing the quality of the thermal-hot dual wedge seams. This test consists of pressurizing the air channel formed by the double seam with a gas to a specific pressure and, then, measuring the decrease in pressure over time. From the pressure decrease, both the gas permeation coefficients, in steady state conditions, and the time constant, in unsteady state conditions, can be estimated. Experiments were

  4. The interaction of insulin, glucose, and insulin-glucose mixtures with a phospholipid monolayer.

    Science.gov (United States)

    Shigenobu, Hayato; McNamee, Cathy E

    2012-12-15

    We determined how glucose or insulin interacts with a phospholipid monolayer at the air/water interface and explained these mechanisms from a physico-chemical point of view. The 1,2-dipalmitoyl-2-sn-glycero-3-phosphatidylcholine (DPPC) monolayer at an air/water interface acted as a model membrane, which allowed the effect of the molecular packing density in the monolayer on the interactions to be determined. The interaction of glucose, insulin, and a mixture of glucose and insulin to the DPPC monolayer were investigated via surface pressure-area per molecule Langmuir isotherms and fluorescence microscopy. Glucose adsorbed to the underside of the DPPC monolayer, while insulin was able to penetrate through the monolayer when the phospholipid molecules were not densely packed. The presence of a mixture of insulin and glucose affected the molecular packing in the DPPC monolayer differently than the pure insulin or glucose solutions, and the glucose-insulin mixture was seen to be able to penetrate through the monolayer. These results indicated that glucose and insulin interact with one another, giving a material that may then transported through a pore in the monolayer or through the spaces between the molecules of the monolayer. Copyright © 2012 Elsevier Inc. All rights reserved.

  5. [Germ cell membrane lipids in spermatogenesis].

    Science.gov (United States)

    Wang, Ting; Shi, Xiao; Quan, Song

    2016-05-01

    Spermatogenesis is a complex developmental process in which a diploid progenitor germ cell transforms into highly specialized spermatozoa. During spermatogenesis, membrane remodeling takes place, and cell membrane permeability and liquidity undergo phase-specific changes, which are all associated with the alteration of membrane lipids. Lipids are important components of the germ cell membrane, whose volume and ratio fluctuate in different phases of spermatogenesis. Abnormal lipid metabolism can cause spermatogenic dysfunction and consequently male infertility. Germ cell membrane lipids are mainly composed of cholesterol, phospholipids and glycolipids, which play critical roles in cell adhesion and signal transduction during spermatogenesis. An insight into the correlation of membrane lipids with spermatogenesis helps us to better understand the mechanisms of spermatogenesis and provide new approaches to the diagnosis and treatment of male infertility.

  6. Quantification of fatty acids as methyl esters and phospholipids in cheese samples after separation of triacylglycerides and phospholipids.

    Science.gov (United States)

    Hauff, Simone; Vetter, Walter

    2009-03-23

    Determination of the individual fatty acid composition of neutral- and phospholipids as well as the phospholipid content of dairy food and other foodstuffs are important tasks in life sciences. For these purposes, a method was developed for the separation of lipids (standards of triolein and diacylphosphatidylcholines as well as three cheese samples) by solid-phase extraction using a self-packed column filled with partly deactivated silica. Non-halogenated solvents were used for the elution of the lipid classes. Cyclohexane/ethyl acetate (1:1, v/v) served for the elution of neutral lipids, while polar lipids were eluted with three solvents (ethyl acetate/methanol, methanol, and methanol/water) into one fraction. The separated lipid fractions were transesterified and the individual fatty acids were quantified by using gas chromatography coupled to electron ionization mass spectrometry (GC/EI-MS) in the selected ion monitoring (SIM) mode. The recovery rate for standard phosphatidylcholines was approximately 90% and cross-contamination from neutral lipids was negligible. The method was applied to cheese samples. Quantitative amounts of individual fatty acids in the phospholipid fraction were camembert, cheese. Differences in the fatty acid pattern of neutral and polar lipids were detected. The quantity of the fatty acids determined in the phospholipid fraction was divided by the factor 0.7 in order to convert the fatty acid content into the phospholipid content of the cheese samples. This factor is based on the contribution of 16:0 to dipalmitoylphosphatidylcholine (DPPC). The resulting DPPC equivalents (DPPC(eq)) were found to be representative for the average contribution of fatty acids to all classes of phospholipids in dairy products. Using this approach, the phospholipid content of lipids from mozzarella, camembert, and goat cream cheese was 0.60%, 1.42% and 0.79%, respectively.

  7. Neutron diffraction on polymorphic phases of phospholipids

    International Nuclear Information System (INIS)

    Adachi, Tomohiro; Furusaka, Michihiro; Otomo, Toshiya; Hatta, Ichiro

    2001-01-01

    Small angle neutron diffraction experiments were performed in DPPC and DPPC/cholesterol systems. We investigated the DPPC-d62 bilayers without cholesterol and the DPPC-d75 bilayers with 5 and 15 mol% cholesterol. For DPPC-d62 systems, in the gel and fluid phase, the reflections up to third order from lamellar structure were observed. Scattering length density profiles of these systems were generated. They show that the packing density of hydrocarbon chain in gel phase is higher than in fluid phase. We show that the neutron diffraction experiment is effective on observing the packing and the scattering length density of the hydrocarbon chain. On the other hand, for DPPC-d75/cholesterol systems, only the reflection from the ripple structure was observed. It shows that cholesterol is periodically localized in accordance with ripple structure forming a periodic bandlike structure parallel to a ridge of the ripple structure. (author)

  8. pH-Induced Changes in the Surface Viscosity of Unsaturated Phospholipids Monitored Using Active Interfacial Microrheology.

    Science.gov (United States)

    Ghazvini, Saba; Alonso, Ryan; Alhakamy, Nabil; Dhar, Prajnaparamita

    2018-01-23

    Lipid membranes, a major component of cells, are subjected to significant changes in pH depending on their location in the cell: the outer leaflet of the cell membrane is exposed to a pH of 7.4 whereas lipid membranes that make up late endosomes and lysosomes are exposed to a pH of as low as 4.4. The purpose of this study is to evaluate how changes in the environmental pH within cells alter the fluidity of phospholipid membranes. Specifically, we studied pH-induced alterations in the surface arrangement of monounsaturated lipids with zwitterionic headgroups (phosphoethanolamine (PE) and phosphocholine (PC)) that are abundant in plasma membranes as well as anionic lipids (phosphatidylserine (PS) and phosphatidylglycerol (PG)) that are abundant in inner membranes using a combination of techniques including surface tension vs area measurements, interfacial microrheology, and fluorescence/atomic force microscopy. Using an active interfacial microrheology technique, we find that phospholipids with zwitterionic headgroups show a significant increase in their surface viscosity at acidic pH. This increase in surface viscosity is also found to depend on the size of the lipid headgroup, with a smaller headgroup showing a greater increase in viscosity. The observed pH-induced increase in viscosity is also accompanied by an increase in the cohesion pressure between zwitterionic molecules at acidic pH and a decrease in the average molecular area of the lipids, as measured by fitting the surface pressure isotherms to well-established equations of state. Because fluorescent images show no change in the phase of the lipids, we attribute this change in surface viscosity to the pH-induced reorientation of the P - -N + dipoles that form part of the polar lipid headgroup, resulting in increased lipid-lipid interactions. Anionic PG headgroups do not demonstrate this pH-induced change in viscosity, suggesting that the presence of a net negative charge on the headgroup causes

  9. Interaction of Local Anesthetics with Biomembranes Consisting of Phospholipids and Cholesterol: Mechanistic and Clinical Implications for Anesthetic and Cardiotoxic Effects

    Directory of Open Access Journals (Sweden)

    Hironori Tsuchiya

    2013-01-01

    Full Text Available Despite a long history in medical and dental application, the molecular mechanism and precise site of action are still arguable for local anesthetics. Their effects are considered to be induced by acting on functional proteins, on membrane lipids, or on both. Local anesthetics primarily interact with sodium channels embedded in cell membranes to reduce the excitability of nerve cells and cardiomyocytes or produce a malfunction of the cardiovascular system. However, the membrane protein-interacting theory cannot explain all of the pharmacological and toxicological features of local anesthetics. The administered drug molecules must diffuse through the lipid barriers of nerve sheaths and penetrate into or across the lipid bilayers of cell membranes to reach the acting site on transmembrane proteins. Amphiphilic local anesthetics interact hydrophobically and electrostatically with lipid bilayers and modify their physicochemical property, with the direct inhibition of membrane functions, and with the resultant alteration of the membrane lipid environments surrounding transmembrane proteins and the subsequent protein conformational change, leading to the inhibition of channel functions. We review recent studies on the interaction of local anesthetics with biomembranes consisting of phospholipids and cholesterol. Understanding the membrane interactivity of local anesthetics would provide novel insights into their anesthetic and cardiotoxic effects.

  10. Hybrid electrospun chitosan-phospholipids nanofibers for transdermal drug delivery

    DEFF Research Database (Denmark)

    Mendes, Ana Carina Loureiro; Gorzelanny, Christian; Halter, Natalia

    2016-01-01

    Chitosan (Ch) polysaccharide was mixed with phospholipids (P) to generate electrospun hybrid nanofibers intended to be used as platforms for transdermal drug delivery. Ch/P nanofibers exibithed average diameters ranging from 248 +/- 94 nm to 600 +/- 201 nm, depending on the amount of phospholipids...... used. Fourier Transformed Infra-Red (FTIR) spectroscopy and Dynamic Light Scattering (DLS) data suggested the occurrence of electrostatic interactions between amine groups of chitosan with the phospholipid counterparts. The nanofibers were shown to be stable for at least 7 days in Phosphate Buffer...... culture plate (control). The release of curcumin, diclofenac and vitamin B12, as model drugs, from Ch/P hybrid nanofibers was investigated, demonstrating their potential utilization as a transdermal drug delivery system....

  11. Stability of sonicated aqueous suspensions of phospholipids under air.

    Science.gov (United States)

    Almog, R; Forward, R; Samsonoff, C

    1991-12-01

    The stability of phospholipids in liposomal aqueous suspension against oxidative degradation in air was investigated using spectrophotometric indices, glutathione peroxidase reactivity and thin layer chromatography. Zwitterionic phospholipid was found to be susceptible to degradation via oxidation of polyunsaturated hydrocarbon chains and ester hydrolysis, producing oxidized lysophosphatide and free fatty acid derivatives. These products were characterized as hydroperoxides based on their reactivity with the selenium-dependent glutathione peroxidase isolated from human erythrocytes. Lecithin in Tris buffer was more resistant to hydrolysis than in water. The sonication of 8.0 mM of soybean phosphatidylcholine (SB-PC) suspension in 0.1 M Tris (pH 7.5) in the presence of air produced relatively high concentration of conjugated diene hydroperoxide, but a small amount of hydrolyzed products. Anionic phospholipids, such as egg-phosphatidylglycerol (egg-PG), demonstrated higher resistance to air oxidation than the zwitterionic lecithin, but its oxidation was promoted by sonication.

  12. Quantification of fatty acids as methyl esters and phospholipids in cheese samples after separation of triacylglycerides and phospholipids

    International Nuclear Information System (INIS)

    Hauff, Simone; Vetter, Walter

    2009-01-01

    Determination of the individual fatty acid composition of neutral- and phospholipids as well as the phospholipid content of dairy food and other foodstuffs are important tasks in life sciences. For these purposes, a method was developed for the separation of lipids (standards of triolein and diacylphosphatidylcholines as well as three cheese samples) by solid-phase extraction using a self-packed column filled with partly deactivated silica. Non-halogenated solvents were used for the elution of the lipid classes. Cyclohexane/ethyl acetate (1:1, v/v) served for the elution of neutral lipids, while polar lipids were eluted with three solvents (ethyl acetate/methanol, methanol, and methanol/water) into one fraction. The separated lipid fractions were transesterified and the individual fatty acids were quantified by using gas chromatography coupled to electron ionization mass spectrometry (GC/EI-MS) in the selected ion monitoring (SIM) mode. The recovery rate for standard phosphatidylcholines was ∼90% and cross-contamination from neutral lipids was negligible. The method was applied to cheese samples. Quantitative amounts of individual fatty acids in the phospholipid fraction were eq ) were found to be representative for the average contribution of fatty acids to all classes of phospholipids in dairy products. Using this approach, the phospholipid content of lipids from mozzarella, camembert, and goat cream cheese was 0.60%, 1.42% and 0.79%, respectively

  13. Small angle neutron scattering and calorimetric studies of large unilamellar vesicles of the phospholipid dipalmitoylphosphatidylcholine

    Energy Technology Data Exchange (ETDEWEB)

    Mason, P.C.; Gaulin, B.D. [Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, L8S 4M1 (CANADA); Epand, R.M. [Department of Biochemistry, McMaster University, Hamilton, Ontario, L8N 3Z5 (CANADA); Wignall, G.D.; Lin, J.S. [Center for Small-Angle Scattering Research, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)

    1999-03-01

    High-resolution differential scanning calorimetry (DSC) and small angle neutron scattering (SANS) experiments have been conducted on large unilamellar vesicles (LUV{close_quote}s) of the phospholipid dipalmitoylphosphatidylcholine (DPPC) in excess water. The DSC results indicate a phase transition at temperatures corresponding to the gel (L{sub {beta}{sup {prime}}}) to ripple (P{sub {beta}{sup {prime}}}) phase transition seen in multilamellar vesicles of DPPC while the SANS experiments provide direct evidence for the formation of the P{sub {beta}{sup {prime}}} phase in these systems. In addition, it is shown that SANS is an effective technique for extracting structural parameters such as vesicle radius and thickness in LUV model membrane systems. {copyright} {ital 1999} {ital The American Physical Society}

  14. Growth and instability of a phospholipid vesicle in a bath of fatty acids

    Science.gov (United States)

    Dervaux, J.; Noireaux, V.; Libchaber, A. J.

    2017-06-01

    Using a microfluidic trap, we study the behavior of individual phospholipid vesicles in contact with fatty acids. We show that spontaneous fatty acids insertion inside the bilayer is controlled by the vesicle size, osmotic pressure difference across the membrane and fatty acids concentration in the external bath. Depending on these parameters, vesicles can grow spherically or become unstable and fragment into several daughter vesicles. We establish the phase diagram for vesicle growth and we derive a simple thermodynamic model that reproduces the time evolution of the vesicle volume. Finally, we show that stable growth can be achieved on an artificial cell expressing a simple set of bacterial cytoskeletal proteins, paving the way toward artificial cell reproduction.

  15. The Small-Angle Neutron Scattering Data Analysis of the Phospholipid Transport Nanosystem Structure

    Science.gov (United States)

    Zemlyanaya, E. V.; Kiselev, M. A.; Zhabitskaya, E. I.; Aksenov, V. L.; Ipatova, O. M.; Ivankov, O. I.

    2018-05-01

    The small-angle neutron scattering technique (SANS) is employed for investigation of structure of the phospholipid transport nanosystem (PTNS) elaborated in the V.N.Orekhovich Institute of Biomedical Chemistry (Moscow, Russia). The SANS spectra have been measured at the YuMO small-angle spectrometer of IBR-2 reactor (Joint Institute of Nuclear Research, Dubna, Russia). Basic characteristics of polydispersed population of PTNS unilamellar vesicles (average radius of vesicles, polydispersity, thickness of membrane, etc.) have been determined in three cases of the PTNS concentrations in D2O: 5%, 10%, and 25%. Numerical analysis is based on the separated form factors method (SFF). The results are discussed in comparison with the results of analysis of the small-angle X-ray scattering spectra collected at the Kurchatov Synchrotron Radiation Source of the National Research Center “Kurchatov Institute” (Moscow, Russia).

  16. Anionic lipids and the maintenance of membrane electrostatics in eukaryotes.

    Science.gov (United States)

    Platre, Matthieu Pierre; Jaillais, Yvon

    2017-02-01

    A wide range of signaling processes occurs at the cell surface through the reversible association of proteins from the cytosol to the plasma membrane. Some low abundant lipids are enriched at the membrane of specific compartments and thereby contribute to the identity of cell organelles by acting as biochemical landmarks. Lipids also influence membrane biophysical properties, which emerge as an important feature in specifying cellular territories. Such parameters are crucial for signal transduction and include lipid packing, membrane curvature and electrostatics. In particular, membrane electrostatics specifies the identity of the plasma membrane inner leaflet. Membrane surface charges are carried by anionic phospholipids, however the exact nature of the lipid(s) that powers the plasma membrane electrostatic field varies among eukaryotes and has been hotly debated during the last decade. Herein, we discuss the role of anionic lipids in setting up plasma membrane electrostatics and we compare similarities and differences that were found in different eukaryotic cells.

  17. Plasma Membrane Ca2+-ATPase 4 in Murine Epididymis: Secretion of Splice Variants in the Luminal Fluid and a Role in Sperm Maturation1

    OpenAIRE

    Patel, Ramkrishna; Al-Dossary, Amal A.; Stabley, Deborah L.; Barone, Carol; Galileo, Deni S.; Strehler, Emanuel E.; Martin-DeLeon, Patricia A.

    2013-01-01

    Plasma membrane Ca2+-ATPase isoform 4 (PMCA4) is the primary Ca2+ efflux pump in murine sperm, where it regulates motility. In Pmca4 null sperm, motility loss results in infertility. We have shown that murine sperm PMCA4b interacts with Ca2+/CaM-dependent serine kinase (CASK) in regulating Ca2+ homeostasis and motility. However, recent work indicated that the bovine PMCA4a splice variant (missing in testis) is epididymally expressed, along with 4b, and may be transferred to sperm. Here we sho...

  18. Fabrication Procedures and Birefringence Measurements for Designing Magnetically Responsive Lanthanide Ion Chelating Phospholipid Assemblies.

    Science.gov (United States)

    Isabettini, Stéphane; Baumgartner, Mirjam E; Fischer, Peter; Windhab, Erich J; Liebi, Marianne; Kuster, Simon

    2018-01-03

    Bicelles are tunable disk-like polymolecular assemblies formed from a large variety of lipid mixtures. Applications range from membrane protein structural studies by nuclear magnetic resonance (NMR) to nanotechnological developments including the formation of optically active and magnetically switchable gels. Such technologies require high control of the assembly size, magnetic response and thermal resistance. Mixtures of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and its lanthanide ion (Ln 3+ ) chelating phospholipid conjugate, 1,2-dimyristoyl-sn-glycero-3-phospho-ethanolamine-diethylene triaminepentaacetate (DMPE-DTPA), assemble into highly magnetically responsive assemblies such as DMPC/DMPE-DTPA/Ln 3+ (molar ratio 4:1:1) bicelles. Introduction of cholesterol (Chol-OH) and steroid derivatives in the bilayer results in another set of assemblies offering unique physico-chemical properties. For a given lipid composition, the magnetic alignability is proportional to the bicelle size. The complexation of Ln 3+ results in unprecedented magnetic responses in terms of both magnitude and alignment direction. The thermo-reversible collapse of the disk-like structures into vesicles upon heating allows tailoring of the assemblies' dimensions by extrusion through membrane filters with defined pore sizes. The magnetically alignable bicelles are regenerated by cooling to 5 °C, resulting in assembly dimensions defined by the vesicle precursors. Herein, this fabrication procedure is explained and the magnetic alignability of the assemblies is quantified by birefringence measurements under a 5.5 T magnetic field. The birefringence signal, originating from the phospholipid bilayer, further enables monitoring of polymolecular changes occurring in the bilayer. This simple technique is complementary to NMR experiments that are commonly employed to characterize bicelles.

  19. Layered plasma polymer composite membranes

    Science.gov (United States)

    Babcock, Walter C.

    1994-01-01

    Layered plasma polymer composite fluid separation membranes are disclosed, which comprise alternating selective and permeable layers for a total of at least 2n layers, where n is .gtoreq.2 and is the number of selective layers.

  20. Membrane dynamics

    DEFF Research Database (Denmark)

    Bendix, Pól Martin

    2015-01-01

    Current topics include membrane-protein interactions with regard to membrane deformation or curvature sensing by BAR domains. Also, we study the dynamics of membrane tubes of both cells and simple model membrane tubes. Finally, we study membrane phase behavior which has important implications...... for the lateral organization of membranes as wells as for physical properties like bending, permeability and elasticity...

  1. Biomimetic mineralization of CaCO3 on a phospholipid monolayer: from an amorphous calcium carbonate precursor to calcite via vaterite.

    Science.gov (United States)

    Xiao, Junwu; Wang, Zhining; Tang, Yecang; Yang, Shihe

    2010-04-06

    A phospholipid monolayer, approximately half the bilayer structure of a biological membrane, can be regarded as an ideal model for investigating biomineralization on biological membranes. In this work on the biomimetic mineralization of CaCO(3) under a phospholipid monolayer, we show the initial heterogeneous nucleation of amorphous calcium carbonate precursor (ACC) nanoparticles at the air-water interface, their subsequent transformation into the metastable vaterite phase instead of the most thermodynamically stable calcite phase, and the ultimate phase transformation to calcite. Furthermore, the spontaneity of the transformation from vaterite to calcite was found to be closely related to the surface tension; high surface pressure could inhibit the process, highlighting the determinant of surface energy. To understand better the mechanisms for ACC formation and the transformation from ACC to vaterite and to calcite, in situ Brewster angle microscopy (BAM), ex situ scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and X-ray diffraction analysis were employed. This work has clarified the crystallization process of calcium carbonate under phospholipid monolayers and therefore may further our understanding of the biomineralization processes induced by cellular membranes.

  2. Post-translational regulation of P2X receptor channels: modulation by phospholipids

    Directory of Open Access Journals (Sweden)

    Louis-Philippe eBernier

    2013-11-01

    Full Text Available P2X receptor channels mediate fast excitatory signaling by ATP and play major roles in sensory transduction, neuro-immune communication and inflammatory response. P2X receptors constitute a gene family of calcium-permeable ATP-gated cation channels therefore the regulation of P2X signaling is critical for both membrane potential and intracellular calcium homeostasis. Phosphoinositides (PIPn are anionic signaling phospholipids that act as functional regulators of many types of ion channels. Direct PIPn binding was demonstrated for several ligand- or voltage-gated ion channels, however no generic motif emerged to accurately predict lipid-protein binding sites. This review presents what is currently known about the modulation of the different P2X subtypes by phospholipids and about critical determinants underlying their sensitivity to PIPn levels in the plasma membrane.All functional mammalian P2X subtypes tested, with the notable exception of P2X5, have been shown to be positively modulated by PIPn, i.e. homomeric P2X1, P2X2, P2X3, P2X4, and P2X7, as well as heteromeric P2X1/5 and P2X2/3 receptors. Based on various results reported on the aforementioned subtypes including mutagenesis of the prototypical PIPn-sensitive P2X4 and PIPn-insensitive P2X5 receptor subtypes, an increasing amount of functional, biochemical and structural evidence converges on the modulatory role of a short polybasic domain located in the proximal C-terminus of P2X subunits. This linear motif, semi-conserved in the P2X family, seems necessary and sufficient for encoding direct modulation of ATP-gated channels by PIPn. Furthermore, the physiological impact of the regulation of ionotropic purinergic responses by phospholipids on pain pathways was recently revealed in the context of native crosstalks between phospholipase C-linked metabotropic receptors and P2X receptor channels in DRG sensory neurons and microglia.

  3. Simulation of Water Transport through a Lipid Membrane

    NARCIS (Netherlands)

    Marrink, Siewert-Jan; Berendsen, Herman J.C.

    1994-01-01

    To obtain insight in the process of water permeation through a lipid membrane, we performed molecular dynamics simulations on a phospholipid (DPPC)/water system with atomic detail. Since the actual process of permeation is too slow to be studied directly, we deduced the permeation rate indirectly

  4. The Plasma Membrane of Saccharomyces cerevisiae : Structure, Function, and Biogenesis

    NARCIS (Netherlands)

    VANDERREST, ME; KAMMINGA, AH; NAKANO, A; ANRAKU, Y; POOLMAN, B; KONINGS, WN

    The composition of phospholipids, sphingolipids, and sterols in the plasma membrane has a strong influence on the activity of the proteins associated or embedded in the lipid bilayer. Since most lipid-synthesizing enzymes in Saccharomyces cerevisiae are located in intracellular organelles, an

  5. Human plasma phospholipid transfer protein increases the antiatherogenic potential of high density lipoproteins in transgenic mice

    NARCIS (Netherlands)

    M.J. van Haperen (Rien); A. van Tol (Arie); P. Vermeulen; M. Jauhiainen; T. van Gent (Teus); P.M. van den Berg (Paul); S. Ehnholm (Sonja); A.W.M. van der Kamp (Arthur); M.P.G. de Crom (Rini); F.G. Grosveld (Frank)

    2000-01-01

    textabstractPlasma phospholipid transfer protein (PLTP) transfers phospholipids between lipoprotein particles and alters high density lipoprotein (HDL) subfraction patterns in vitro, but its physiological function is poorly understood. Transgenic mice that overexpress

  6. A novel isolation strategy for obtaining crude membrane vesicles from bovine skim milk

    DEFF Research Database (Denmark)

    Blans, Kristine; Larsen, Lotte Bach; Wiking, Lars

    Bovine milks content of phospholipid membranes have largely been explored in the cream fraction, and known as the milk fat globule membrane that surrounds fat droplets. In skim milk, the population of phospholipid membranes is reported to constitute membrane vesicles with a soluble content known...... is observed all over the gradient. The variety of the membrane vesicles is currently being investigated further by several means. Summary/conclusion: A new procedure for easy and gentle isolation of bovine milk membrane vesicles encompassing ultracentrifugation and size-exclusion chromatography has been...... established. The resulting vesicle isolate exhibits the general membrane vesicle characteristics and provides an appropriate start material from which the variety of milk vesicles can be investigated...

  7. A mitochondrially targeted compound delays aging in yeast through a mechanism linking mitochondrial membrane lipid metabolism to mitochondrial redox biology

    Directory of Open Access Journals (Sweden)

    Michelle T. Burstein

    2014-01-01

    Full Text Available A recent study revealed a mechanism of delaying aging in yeast by a natural compound which specifically impacts mitochondrial redox processes. In this mechanism, exogenously added lithocholic bile acid enters yeast cells, accumulates mainly in the inner mitochondrial membrane, and elicits an age-related remodeling of phospholipid synthesis and movement within both mitochondrial membranes. Such remodeling of mitochondrial phospholipid dynamics progresses with the chronological age of a yeast cell and ultimately causes significant changes in mitochondrial membrane lipidome. These changes in the composition of membrane phospholipids alter mitochondrial abundance and morphology, thereby triggering changes in the age-related chronology of such longevity-defining redox processes as mitochondrial respiration, the maintenance of mitochondrial membrane potential, the preservation of cellular homeostasis of mitochondrially produced reactive oxygen species, and the coupling of electron transport to ATP synthesis.

  8. Probing lipid membrane electrostatics

    Science.gov (United States)

    Yang, Yi

    The electrostatic properties of lipid bilayer membranes play a significant role in many biological processes. Atomic force microscopy (AFM) is highly sensitive to membrane surface potential in electrolyte solutions. With fully characterized probe tips, AFM can perform quantitative electrostatic analysis of lipid membranes. Electrostatic interactions between Silicon nitride probes and supported zwitterionic dioleoylphosphatidylcholine (DOPC) bilayer with a variable fraction of anionic dioleoylphosphatidylserine (DOPS) were measured by AFM. Classical Gouy-Chapman theory was used to model the membrane electrostatics. The nonlinear Poisson-Boltzmann equation was numerically solved with finite element method to provide the potential distribution around the AFM tips. Theoretical tip-sample electrostatic interactions were calculated with the surface integral of both Maxwell and osmotic stress tensors on tip surface. The measured forces were interpreted with theoretical forces and the resulting surface charge densities of the membrane surfaces were in quantitative agreement with the Gouy-Chapman-Stern model of membrane charge regulation. It was demonstrated that the AFM can quantitatively detect membrane surface potential at a separation of several screening lengths, and that the AFM probe only perturbs the membrane surface potential by external field created by the internai membrane dipole moment. The analysis yields a dipole moment of 1.5 Debye per lipid with a dipole potential of +275 mV for supported DOPC membranes. This new ability to quantitatively measure the membrane dipole density in a noninvasive manner will be useful in identifying the biological effects of the dipole potential. Finally, heterogeneous model membranes were studied with fluid electric force microscopy (FEFM). Electrostatic mapping was demonstrated with 50 nm resolution. The capabilities of quantitative electrostatic measurement and lateral charge density mapping make AFM a unique and powerful

  9. Effects of X-irradiation on membranes of tumor cells

    International Nuclear Information System (INIS)

    Fonck, K.

    1982-01-01

    The aim of the investigation was to gain more insight into the effect of ionizing radiation on biomembranes, especially the membrane phospholipids. A general outline of the experimental approach is given in the first chapter. The influence of membrane-active agents and hyperthermia on cell survival after irradiation was studied. Phospholipid turnover was followed by measuring the incorporation of radioactive precursors. The second chapter is an introduction to general radiobiology and to phospholipid metabolism. After the presentation of some physico-chemical properties of ionizing radiation, the effects on cells and cellular components are described. In chapters 3 to 6 the experimental part is described. Chapter 3 starts with the determination of the cellular survival of L5178Y lymphoma cells after X-irradiation. In chapter 4 the lipid composition of lymphosarcoma cell nuclei is presented and in chapter 5 studies on the effect of X-irradiation on the incorporation of palmitate and arachidonate into the phospholipids of lymphosarcoma cells are described. Chapter 6 describes experiments in which lymphosarcoma cells isolated from the spleens of tumor-bearing mice were used to study the effect of a low dose of X-rays (5 Gy) on the incorporation of [ 3 H]palmitate and [ 14 C]arachidonate into the lipids of the tumor cells. These fatty acids were rapidly incorporated especially into the phospholipids of the cells. Chapter 7 contains a general discussion on the experimental results. (Auth.)

  10. Using crosslinkable diacetylene phospholipids to construct two-dimensional packed beds in supported lipid bilayer separation platforms

    Directory of Open Access Journals (Sweden)

    Shu-Kai Hu, Sheng-Wen Hsiao, Hsun-Yen Mao, Ya-Ming Chen, Yung Chang and Ling Chao

    2013-01-01

    Full Text Available Separating and purifying cell membrane-associated biomolecules has been a challenge owing to their amphiphilic property. Taking these species out of their native lipid membrane environment usually results in biomolecule degradation. One of the new directions is to use supported lipid bilayer (SLB platforms to separate the membrane species while they are protected in their native environment. Here we used a type of crosslinkable diacetylene phospholipids, diynePC (1,2-bis(10,12-tricosadiynoyl-sn-glycero-3-phosphocholine, as a packed material to create a 'two-dimensional (2D packed bed' in a SLB platform. After the diynePC SLB is exposed to UV light, some of the diynePC lipids in the SLB can crosslink and the non-crosslinked monomer lipids can be washed away, leaving a 2D porous solid matrix. We incorporated the lipid vesicle deposition method with a microfluidic device to pattern the location of the packed-bed region and the feed region with species to be separated in a SLB platform. Our atomic force microscopy result shows that the nano-scaled structure density of the '2D packed bed' can be tuned by the UV dose applied to the diynePC membrane. When the model membrane biomolecules were forced to transport through the packed-bed region, their concentration front velocities were found to decrease linearly with the UV dose, indicating the successful creation of packed obstacles in these 2D lipid membrane separation platforms.

  11. Dynamic combinatorial chemistry at the phospholipid bilayer interface

    NARCIS (Netherlands)

    Mansfeld, Friederike M.; Au-Yeung, Ho Yu; Sanders, Jeremy K.M.; Otto, Sijbren

    2010-01-01

    Background: Molecular recognition at the environment provided by the phospholipid bilayer interface plays an important role in biology and is subject of intense investigation. Dynamic combinatorial chemistry is a powerful approach for exploring molecular recognition, but has thus far not been

  12. Soft contact lens biomaterials from bioinspired phospholipid polymers.

    Science.gov (United States)

    Goda, Tatsuro; Ishihara, Kazuhiko

    2006-03-01

    Soft contact lens (SCL) biomaterials originated from the discovery of a poly(2-hydroxyethyl methacrylate) (poly[HEMA])-based hydrogel in 1960. Incorporation of hydrophilic polymers into poly(HEMA) hydrogels was performed in the 1970-1980s, which brought an increase in the equilibrium water content, leading to an enhancement of the oxygen permeability. Nowadays, the poly(HEMA)-based hydrogels have been applied in disposable SCL. At the same time, high oxygen-permeable silicone hydrogels were produced, which made it possible to continually wear SCL. Recently, numerous trials for improving the water wettability of silicone hydrogels have been performed. However, little attention has been paid to improving their anti-biofouling properties and biocompatibility. Since biomimetic phospholipid polymers possess excellent anti-biofouling properties and biocompatibility they have the potential to play a valuable role in the surface modification of the silicone hydrogel. The representative phospholipid polymers containing a 2-methacryloyloxyethyl phosphorylcholine (MPC) unit suppressed nonspecific protein adsorption, increased cell compatibility and contributed to blood compatible biomaterials. The MPC polymer coating on the silicone hydrogel improved its water wettability and biocompatibility, while maintaining high oxygen permeability compared with the original silicone hydrogel. Furthermore, the newly prepared phospholipid-type intermolecular crosslinker made it possible to synthesize a 100% phospholipid polymer hydrogel that can enhance the anti-biofouling properties and biocompatibility. In this review, the authors discuss how polymer hydrogels should be designed in order to obtain a biocompatible SCL and future perspectives.

  13. Phospholipid transfer protein activity and incident type 2 diabetes mellitus

    NARCIS (Netherlands)

    Abbasi, Ali; Dallinga-Thie, Geesje M.; Dullaart, Robin P. F.

    2015-01-01

    The plasma activity of phospholipid transfer protein (PLTP), which has multifaceted functions in lipoprotein metabolism and in inflammatory responses, is elevated in insulin resistant conditions. We determined the association of plasma PLTP activity with incident type 2 diabetes mellitus (T2DM).

  14. PHOSPHOLIPIDS OF FIVE PSEUDOMONAD ARCHETYPES FOR DIFFERENT TOLUENE DEGRADATION PATHWAYS

    Science.gov (United States)

    Liquid chromatography/electrospray ionization/mass spectrometry (LC/ESI/MS) was used to determine phospholipid profiles for five reference pseudomonad strains harboring distinct toluene catabolic pathways: Pseudomonas putida mt-2, Pseudomonas putida F1, Burkholderia cepacia G4, B...

  15. Effects of phospholipids in the diet on biochemical factors of ...

    African Journals Online (AJOL)

    A study was carried out to determine the influence of dietary phospholipids biochemical factors parameters of beluga sturgeon (Huso huso) juveniles. Juveniles were fed formulated diet with four varying dietary levels of PL, that is, 0 (D1), 2 (D2), 4 (D3) and 6% (D4). At the end of the experimental period (56 days), there were ...

  16. Anti-Phospholipid Syndrome In Nigeria: Report Of Five Cases ...

    African Journals Online (AJOL)

    Five cases of secondary anti-phospholipid syndrome (APS) are presented and literature reviewed. Pregnancy loss was the most common presentation but neurologic manifestations are also seen. IgG ACA was more commonly seen than IgM ACA. Although APS has been infrequently reported in black Africans, ...

  17. Enzyme catalysed production of phospholipids with modified fatty acid profile

    DEFF Research Database (Denmark)

    Vikbjerg, Anders Falk

    2006-01-01

    Phospholipider har stor anvendelse i levnedsmiddel-, kosmetik-, og farmaceutiske produkter for blandt andet deres emulgerende egenskaber samt evne til at danne liposomer. Interessen for at ændre på phospholipidernes struktur er stigende. Strukturændringer resulterer i ændret funktionalitet. Ved u...

  18. Asymmetric incorporation of Na+, K+-ATPase into phospholipid vesicles

    NARCIS (Netherlands)

    Jackson, R.L.; Verkleij, A.J.; Zoelen, E.J.J. van; Lane, L.K.; Schwartz, A.; Deenen, L.L.M. van

    Purified lamb kidney Na+, K+-ATPase, consisting solely of the Mτ = 95,000 catalytic subunit and the Mτ- 44,000 glycoprotein, was solubilized with Triton X-100 and incorporated into unilamellar phospholipid vesicles. Freeze-fracture electron microscopy of the vesicles showed intramembranous particles

  19. Role of phospholipids in the pathophysiology of the gut-liver axis

    NARCIS (Netherlands)

    Petruzzelli, M.

    2010-01-01

    Phospholipids represent essential components of bile. Together with bile acids and cholesterol, phospholipids form “mixed micelles”. If sufficient amounts of phospholipids are available, no simple bile acid micelles are present, with prevention of bile acid toxicity and cholesterol crystallization.

  20. The N-terminal segment of pulmonary surfactant lipopeptide SP-C has intrinsic propensity to interact with and perturb phospholipid bilayers

    DEFF Research Database (Denmark)

    Plasencia, Inés; Rivas, Luis; Keough, Kevin M W

    2004-01-01

    aggregation, and leakage of the aqueous content of the vesicles. The lipid-peptide interaction includes a significant hydrophobic component for both zwitterionic and anionic membranes, although the interaction with phosphatidylglycerol bilayers is also electrostatic in nature. The effects of the SP-C N......-terminal peptides on the membrane structure are mediated by significant perturbations of the packing order and mobility of phospholipid acyl chain segments deep in the bilayer, as detected by differential scanning calorimetry and spin-label ESR. These results suggest that the N-terminal region of SP-C, even...

  1. The role of antioxidant-protein interactions in biological membrane

    International Nuclear Information System (INIS)

    McGillivray, Duncan J; Singh, Rachna; Melton, Laurence D.; Worcester, David L.; Gilbert, Elliot P.

    2009-01-01

    Full text: Oxidative damage of cellular membranes has been linked to a variety of disease pathologies, including cardiac disease, Alzheimer's and complications due to diabetes. The oxidation of unsaturated and polyunsaturated fatty acid chains found in cellular membranes leads to significant alteration in membrane physical properties, including lipid orientation and membrane permeability, which ultimately affect biological function. Polyphenols are naturally occurring phytochemicals present in a number of fruit and vegetables that are of interest for their anti-oxidative powers. These polyphenols inhibit lipid oxidation in cellular membrane surfaces, although the mechanism of this inhibition is not entirely clear. Moreover, the polyphenols have significant binding affinity for proteins, which can lead to the formation of soluble and insoluble protein-polyphenol complexes Significantly, in the presence of casein proteins the oxidation inhibition the polyphenols in the membrane is significantly enhanced (as assessed by Lipid Peroxidation Inhibition Capacity assays). Thus the antioxidant pathway appears to involve these protein/polyphenol complexes, as well as direct antioxidant action by the polyphenol. Here we discuss neutron and x-ray scattering results from phospholipid membranes, looking at the positioning of two examples of polyphenolic antioxidants in phospholipid membranes, quercetin and phloretin, the antioxidants' impact on the membrane organisation, and the interaction between antioxidant and extra-membranous protein. This information sheds light on the mechanism of antioxidant protection in these systems, which may be used to understand biological responses to oxidative stress.

  2. Fatty acid composition of total lipids and phospholipids of muscular tissue and brain of rats under the impact of vibration

    Directory of Open Access Journals (Sweden)

    N. M. Kostyshyn

    2016-06-01

    Full Text Available Fatty acids are important structural components of biological membranes, energy substrate of cells involved in fixing phospholipid bilayer proteins, and acting as regulators and modulators of enzymatic activity. Under the impact of vibration oscillations there can occur shifts in the ratio of different groups of fatty acids, and degrees of their saturation may change. The imbalance between saturated, monounsaturated and polyunsaturated fatty acids, which occurs later in the cell wall, disrupts fluidity and viscosity of lipid phase and causes abnormal cellular metabolism. Aim. In order to study the impact of vibration on the level of fatty acids of total lipids in muscular tissue and fatty acid composition of phospholipids in muscles and brain, experimental animals have been exposed to vertical vibration oscillations with different frequency for 28 days. Methods and results. Tissues fragments of hip quadriceps and brain of rats were used for obtaining methyl esters of fatty acids studied by the method of gas-liquid chromatography. It was found that the lipid content, ratio of its separate factions and fatty acid composition in muscular tissue and brain of animals with the action of vibration considerably varies. With the increase of vibration acceleration tendency to increase in absolute quantity of total lipids fatty acids can be observed at the account of increased level of saturated and monounsaturated ones. These processes are caused by activation of self-defense mechanisms of the body under the conditions of deviations from stabilized physiological norm, since adaptation requires certain structural and energy costs. Increase in the relative quantity of saturated and monounsaturated fatty acids in phospholipids of muscles and brain and simultaneous reduction in concentration of polyunsaturated fatty acids are observed. Conclusion. These changes indicate worsening of structural and functional organization of muscles and brain cell membranes of

  3. Decrumpling membranes by quantum effects

    Science.gov (United States)

    Borelli, M. E. S.; Kleinert, H.

    2001-02-01

    The phase diagram of an incompressible fluid membrane subject to quantum and thermal fluctuations is calculated exactly in a large number of dimensions of configuration space. At zero temperature, a crumpling transition is found at a critical bending rigidity 1/αc. For membranes of fixed lateral size, a crumpling transition occurs at nonzero temperatures in an auxiliary mean field approximation. As the lateral size L of the membrane becomes large, the flat regime shrinks with 1/ln L.

  4. Quantification of fatty acids as methyl esters and phospholipids in cheese samples after separation of triacylglycerides and phospholipids

    Energy Technology Data Exchange (ETDEWEB)

    Hauff, Simone [University of Hohenheim, Institute of Food Chemistry, Garbenstrasse 28, D-70599 Stuttgart (Germany); Vetter, Walter [University of Hohenheim, Institute of Food Chemistry, Garbenstrasse 28, D-70599 Stuttgart (Germany)], E-mail: w-vetter@uni-hohenheim.de

    2009-03-23

    Determination of the individual fatty acid composition of neutral- and phospholipids as well as the phospholipid content of dairy food and other foodstuffs are important tasks in life sciences. For these purposes, a method was developed for the separation of lipids (standards of triolein and diacylphosphatidylcholines as well as three cheese samples) by solid-phase extraction using a self-packed column filled with partly deactivated silica. Non-halogenated solvents were used for the elution of the lipid classes. Cyclohexane/ethyl acetate (1:1, v/v) served for the elution of neutral lipids, while polar lipids were eluted with three solvents (ethyl acetate/methanol, methanol, and methanol/water) into one fraction. The separated lipid fractions were transesterified and the individual fatty acids were quantified by using gas chromatography coupled to electron ionization mass spectrometry (GC/EI-MS) in the selected ion monitoring (SIM) mode. The recovery rate for standard phosphatidylcholines was {approx}90% and cross-contamination from neutral lipids was negligible. The method was applied to cheese samples. Quantitative amounts of individual fatty acids in the phospholipid fraction were <0.002-0.29% of total lipids from camembert, <0.002-0.12% of total lipids from mozzarella, and <0.002-0.18% of total lipids in a goat cream cheese. Differences in the fatty acid pattern of neutral and polar lipids were detected. The quantity of the fatty acids determined in the phospholipid fraction was divided by the factor 0.7 in order to convert the fatty acid content into the phospholipid content of the cheese samples. This factor is based on the contribution of 16:0 to dipalmitoylphosphatidylcholine (DPPC). The resulting DPPC equivalents (DPPC{sub eq}) were found to be representative for the average contribution of fatty acids to all classes of phospholipids in dairy products. Using this approach, the phospholipid content of lipids from mozzarella, camembert, and goat cream cheese

  5. Atomistic Monte Carlo simulation of lipid membranes

    DEFF Research Database (Denmark)

    Wüstner, Daniel; Sklenar, Heinz

    2014-01-01

    Biological membranes are complex assemblies of many different molecules of which analysis demands a variety of experimental and computational approaches. In this article, we explain challenges and advantages of atomistic Monte Carlo (MC) simulation of lipid membranes. We provide an introduction...... into the various move sets that are implemented in current MC methods for efficient conformational sampling of lipids and other molecules. In the second part, we demonstrate for a concrete example, how an atomistic local-move set can be implemented for MC simulations of phospholipid monomers and bilayer patches...

  6. Dynamics and energetics of the mammalian phosphatidylinositol transfer protein phospholipid exchange cycle.

    Science.gov (United States)

    Grabon, Aby; Orłowski, Adam; Tripathi, Ashutosh; Vuorio, Joni; Javanainen, Matti; Róg, Tomasz; Lönnfors, Max; McDermott, Mark I; Siebert, Garland; Somerharju, Pentti; Vattulainen, Ilpo; Bankaitis, Vytas A

    2017-09-01

    Phosphatidylinositol-transfer proteins (PITPs) regulate phosphoinositide signaling in eukaryotic cells. The defining feature of PITPs is their ability to exchange phosphatidylinositol (PtdIns) molecules between membranes, and this property is central to PITP-mediated regulation of lipid signaling. However, the details of the PITP-mediated lipid exchange cycle remain entirely obscure. Here, all-atom molecular dynamics simulations of the mammalian StART-like PtdIns/phosphatidylcholine (PtdCho) transfer protein PITPα, both on membrane bilayers and in solvated systems, informed downstream biochemical analyses that tested key aspects of the hypotheses generated by the molecular dynamics simulations. These studies provided five key insights into the PITPα lipid exchange cycle: (i) interaction of PITPα with the membrane is spontaneous and mediated by four specific protein substructures; (ii) the ability of PITPα to initiate closure around the PtdCho ligand is accompanied by loss of flexibility of two helix/loop regions, as well as of the C-terminal helix; (iii) the energy barrier of phospholipid extraction from the membrane is lowered by a network of hydrogen bonds between the lipid molecule and PITPα; (iv) the trajectory of PtdIns or PtdCho into and through the lipid-binding pocket is chaperoned by sets of PITPα residues conserved throughout the StART-like PITP family; and (v) conformational transitions in the C-terminal helix have specific functional involvements in PtdIns transfer activity. Taken together, these findings provide the first mechanistic description of key aspects of the PITPα PtdIns/PtdCho exchange cycle and offer a rationale for the high conservation of particular sets of residues across evolutionarily distant members of the metazoan StART-like PITP family. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  7. Determination of the separate lipid and protein profile structures derived from the total membrane profile structure or isolated sarcoplasmic reticulum via x-ray and neutron diffraction

    International Nuclear Information System (INIS)

    Herbette, L.; Blasie, J.K.

    1984-01-01

    Sarcoplasmic reticulum (SR) membranes were prepared to contain biosynthetically deuterated SR phospholipids utilizing specific and general phospholipid exchange proteins (PLEP). Functional measurements and freeze fracture on SR dispersions and x-ray diffraction of hydrated oriented membrane multilayers revealed that the exchanged SR membranes were very similar to unexchanged SR membranes. Low resolution (28-A) neutron diffraction studies utilizing SR membranes exchanged with either protonated or perdeuterated SR phospholipids allowed direct determination of the lipid profile within the isolated SR membrane at two different unit cell repeat distances. These lipid profile structures were found to be highly asymmetric regarding the conformation of the fatty acid chain extents and compositional distribution of phospholipid molecules in the inner vs. outer monolayer of the SR membrane bilayer. The relatively high resolution (11-A) electron-density profile from x-ray diffraction was decomposed by utilizing the asymmetry in the number of phospholipid molecules residing in the inner vs. outer monolayer of the SR lipid bilayer as obtained from the neutron diffraction study. To our knowledge, this represents the first direct determination of a lipid bilayer profile structure within an isolated membrane system

  8. Insulin and adenosine regulate the phosphatidylcholine concentration in isolated rat adipocyte plasma membranes.

    Science.gov (United States)

    Kiechle, F L; Sykes, E; Artiss, J D

    1995-01-01

    Blockade of adenosine receptors by 3-isobutyl-1-methylxanthine or degradation of endogenous adenosine with adenosine deaminase increased the phosphatidylcholine concentration in isolated rat adipocyte plasma membranes, an effect which was suppressed by the phosphatidylethanolamine methyltransferase inhibitor, S-adenosyl-L-homocysteine, and reversed by the adenosine analogue, N6-(L-phenylisopropyl)-adenosine. For example, the addition of N6-(L-phenylisopropyl)-adenosine to adenosine deaminase pretreated plasma membranes rapidly lowered the concentration of phosphatidylcholine by 171 nmol/mg at 30 seconds compared to control. Insulin-induced stimulation of phospholipid methylation in membranes treated with 3-isobutyl-1-methylxanthine or adenosine deaminase was achieved only after the addition of N6-(L-phenylisopropyl)-adenosine. These results suggest that adenosine receptor occupancy inhibits phospholipid methylation, is required for insulin stimulation of phospholipid methylation, and may perhaps activate a phosphatidylcholine-specific phospholipase C or phospholipase D.

  9. High Fat Diet-Induced Changes in Mouse Muscle Mitochondrial Phospholipids Do Not Impair Mitochondrial Respiration Despite Insulin Resistance

    Science.gov (United States)

    Hulshof, Martijn F. M.; van den Berg, Sjoerd A. A.; Schaart, Gert; van Dijk, Ko Willems; Smit, Egbert; Mariman, Edwin C. M.

    2011-01-01

    Background Type 2 diabetes mellitus and muscle insulin resistance have been associated with reduced capacity of skeletal muscle mitochondria, possibly as a result of increased intake of dietary fat. Here, we examined the hypothesis that a prolonged high-fat diet consumption (HFD) increases the saturation of muscle mitochondrial membrane phospholipids causing impaired mitochondrial oxidative capacity and possibly insulin resistance. Methodology C57BL/6J mice were fed an 8-week or 20-week low fat diet (10 kcal%; LFD) or HFD (45 kcal%). Skeletal muscle mitochondria were isolated and fatty acid (FA) composition of skeletal muscle mitochondrial phospholipids was analyzed by thin-layer chromatography followed by GC. High-resolution respirometry was used to assess oxidation of pyruvate and fatty acids by mitochondria. Insulin sensitivity was estimated by HOMA-IR. Principal Findings At 8 weeks, mono-unsaturated FA (16∶1n7, 18∶1n7 and 18∶1n9) were decreased (−4.0%, p<0.001), whereas saturated FA (16∶0) were increased (+3.2%, p<0.001) in phospholipids of HFD vs. LFD mitochondria. Interestingly, 20 weeks of HFD descreased mono-unsaturated FA while n-6 poly-unsaturated FA (18∶2n6, 20∶4n6, 22∶5n6) showed a pronounced increase (+4.0%, p<0.001). Despite increased saturation of muscle mitochondrial phospholipids after the 8-week HFD, mitochondrial oxidation of both pyruvate and fatty acids were similar between LFD and HFD mice. After 20 weeks of HFD, the increase in n-6 poly-unsaturated FA was accompanied by enhanced maximal capacity of the electron transport chain (+49%, p = 0.002) and a tendency for increased ADP-stimulated respiration, but only when fuelled by a lipid-derived substrate. Insulin sensitivity in HFD mice was reduced at both 8 and 20 weeks. Conclusions/Interpretation Our findings do not support the concept that prolonged HF feeding leads to increased saturation of skeletal muscle mitochondrial phospholipids resulting in a decrease in

  10. High fat diet-induced changes in mouse muscle mitochondrial phospholipids do not impair mitochondrial respiration despite insulin resistance.

    Directory of Open Access Journals (Sweden)

    Joris Hoeks

    Full Text Available BACKGROUND: Type 2 diabetes mellitus and muscle insulin resistance have been associated with reduced capacity of skeletal muscle mitochondria, possibly as a result of increased intake of dietary fat. Here, we examined the hypothesis that a prolonged high-fat diet consumption (HFD increases the saturation of muscle mitochondrial membrane phospholipids causing impaired mitochondrial oxidative capacity and possibly insulin resistance. METHODOLOGY: C57BL/6J mice were fed an 8-week or 20-week low fat diet (10 kcal%; LFD or HFD (45 kcal%. Skeletal muscle mitochondria were isolated and fatty acid (FA composition of skeletal muscle mitochondrial phospholipids was analyzed by thin-layer chromatography followed by GC. High-resolution respirometry was used to assess oxidation of pyruvate and fatty acids by mitochondria. Insulin sensitivity was estimated by HOMA-IR. PRINCIPAL FINDINGS: At 8 weeks, mono-unsaturated FA (16∶1n7, 18∶1n7 and 18∶1n9 were decreased (-4.0%, p<0.001, whereas saturated FA (16∶0 were increased (+3.2%, p<0.001 in phospholipids of HFD vs. LFD mitochondria. Interestingly, 20 weeks of HFD descreased mono-unsaturated FA while n-6 poly-unsaturated FA (18∶2n6, 20∶4n6, 22∶5n6 showed a pronounced increase (+4.0%, p<0.001. Despite increased saturation of muscle mitochondrial phospholipids after the 8-week HFD, mitochondrial oxidation of both pyruvate and fatty acids were similar between LFD and HFD mice. After 20 weeks of HFD, the increase in n-6 poly-unsaturated FA was accompanied by enhanced maximal capacity of the electron transport chain (+49%, p = 0.002 and a tendency for increased ADP-stimulated respiration, but only when fuelled by a lipid-derived substrate. Insulin sensitivity in HFD mice was reduced at both 8 and 20 weeks. CONCLUSIONS/INTERPRETATION: Our findings do not support the concept that prolonged HF feeding leads to increased saturation of skeletal muscle mitochondrial phospholipids resulting in a decrease in

  11. Changing rooster sperm membranes to facilitate cryopreservation

    Science.gov (United States)

    Cryopreservation damages rooster sperm membranes. Part of this damage is due to membrane transitioning from the fluid to the gel state as temperature is reduced. This damage may be prevented by increasing membrane fluidity at low temperatures by incorporating cholesterol or unsaturated lipids into t...

  12. Cholesterol affects the interaction between an ionic liquid and phospholipid vesicles. A study by differential scanning calorimetry and nanoplasmonic sensing.

    Science.gov (United States)

    Russo, Giacomo; Witos, Joanna; Rantamäki, Antti H; Wiedmer, Susanne K

    2017-12-01

    The present work aims at studying the interactions between cholesterol-rich phosphatidylcholine-based lipid vesicles and trioctylmethylphosphonium acetate ([P 8881 ][OAc]), a biomass dissolving ionic liquid (IL). The effect of cholesterol was assayed by using differential scanning calorimetry (DSC) and nanoplasmonic sensing (NPS) measurement techniques. Cholesterol-enriched dipalmitoyl-phosphatidylcholine vesicles were exposed to different concentrations of the IL, and the derived membrane perturbation was monitored by DSC. The calorimetric data could suggest that the binding and infiltration of the IL are delayed in the vesicles containing cholesterol. To clarify our findings, NPS was applied to quantitatively follow the resistance of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine incorporating 0, 10, and 50mol% of cholesterol toward the IL exposure over time. The membrane perturbation induced by different concentrations of IL was found to be a concentration dependent process on cholesterol-free lipid vesicles. Moreover, our results showed that lipid depletion in cholesterol-enriched lipid vesicles is inversely proportional to the increasing amount of cholesterol in the vesicles. These findings support that cholesterol-rich lipid bilayers are less susceptible toward membrane disrupting agents as compared to membranes that do not incorporate any sterols. This probably occurs because cholesterol tightens the phospholipid acyl chain packing of the plasma membranes, increasing their resistance and reducing their permeability. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Drug Clearance from Cerebrospinal Fluid Mediated by Organic Anion Transporters 1 (Slc22a6) and 3 (Slc22a8) at Arachnoid Membrane of Rats.

    Science.gov (United States)

    Zhang, Zhengyu; Tachikawa, Masanori; Uchida, Yasuo; Terasaki, Tetsuya

    2018-03-05

    Although arachnoid mater epithelial cells form the blood-arachnoid barrier (BAB), acting as a blood-CSF interface, it has been generally considered that the BAB is impermeable to water-soluble substances and plays a largely passive role. Here, we aimed to clarify the function of transporters at the BAB in regulating CSF clearance of water-soluble organic anion drugs based on quantitative targeted absolute proteomics (QTAP) and in vivo analyses. Protein expression levels of 61 molecules, including 19 ATP-binding-cassette (ABC) transporters and 32 solute-carrier (SLC) transporters, were measured in plasma membrane fraction of rat leptomeninges using QTAP. Thirty-three proteins were detected; others were under the quantification limits. Expression levels of multidrug resistance protein 1 (Mdr1a/P-gp/Abcb1a) and breast cancer resistance protein (Bcrp/Abcg2) were 16.6 and 3.27 fmol/μg protein (51.9- and 9.82-fold greater than in choroid plexus, respectively). Among those organic anion transporters detected only at leptomeninges, not choroid plexus, organic anion transporter 1 (oat1/Slc22a6) showed the greatest expression (2.73 fmol/μg protein). On the other hand, the protein expression level of oat3 at leptomeninges was 6.65 fmol/μg protein, and the difference from choroid plexus was within two-fold. To investigate oat1's role, we injected para-aminohippuric acid (PAH) with or without oat1 inhibitors into cisterna magna (to minimize the contribution of choroid plexus function) of rats. A bulk flow marker, FITC-inulin, was not taken up from CSF up to 15 min, whereas uptake clearance of PAH was 26.5 μL/min. PAH uptake was completely blocked by 3 mM cephalothin (inhibits both oat1 and oat3), while 17% of PAH uptake was inhibited by 0.2 mM cephalothin (selectively inhibits oat3). These results indicate that oat1 and oat3 at the BAB provide a distinct clearance pathway of organic anion drugs from CSF independently of choroid plexus.

  14. Insertable fluid flow passage bridgepiece and method

    Science.gov (United States)

    Jones, Daniel O.

    2000-01-01

    A fluid flow passage bridgepiece for insertion into an open-face fluid flow channel of a fluid flow plate is provided. The bridgepiece provides a sealed passage from a columnar fluid flow manifold to the flow channel, thereby preventing undesirable leakage into and out of the columnar fluid flow manifold. When deployed in the various fluid flow plates that are used in a Proton Exchange Membrane (PEM) fuel cell, bridgepieces of this invention prevent mixing of reactant gases, leakage of coolant or humidification water, and occlusion of the fluid flow channel by gasket material. The invention also provides a fluid flow plate assembly including an insertable bridgepiece, a fluid flow plate adapted for use with an insertable bridgepiece, and a method of manufacturing a fluid flow plate with an insertable fluid flow passage bridgepiece.

  15. Molecular engineering of lanthanide ion chelating phospholipids generating assemblies with a switched magnetic susceptibility.

    Science.gov (United States)

    Isabettini, Stéphane; Massabni, Sarah; Hodzic, Arnel; Durovic, Dzana; Kohlbrecher, Joachim; Ishikawa, Takashi; Fischer, Peter; Windhab, Erich J; Walde, Peter; Kuster, Simon

    2017-08-09

    Lanthanide ion (Ln 3+ ) chelating amphiphiles are powerful molecules for tailoring the magnetic response of polymolecular assemblies. Mixtures of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-dimyristoyl-sn-glycero-3-phospho-ethanolamine-diethylene triaminepentaacetate (DMPE-DTPA) complexed to Ln 3+ deliver highly magnetically responsive bicelles. Their magnetic properties are readily tuned by changing the bicellar size or the magnetic susceptibility Δχ of the bilayer lipids. The former technique is intrinsically bound to the region of the phase diagram guarantying the formation of bicelles. Methods aiming towards manipulating the Δχ of the bilayer are comparatively more robust, flexible and lacking. Herein, we synthesized a new Ln 3+ chelating phospholipid using glutamic acid as a backbone: DMPE-Glu-DTPA. The chelate polyhedron was specifically engineered to alter the Δχ, whilst remaining geometrically similar to DMPE-DTPA. Planar asymmetric assemblies hundreds of nanometers in size were achieved presenting unprecedented magnetic alignments. The DMPE-Glu-DTPA/Ln 3+ complex switched the Δχ, achieving perpendicular alignment of assemblies containing Dy 3+ and parallel alignment of those containing Tm 3+ . Moreover, samples with chelated Yb 3+ were more alignable than the Tm 3+ chelating counterparts. Such a possibility has never been demonstrated for planar Ln 3+ chelating polymolecular assemblies. The physico-chemical properties of these novel assemblies were further studied by monitoring the alignment behavior at different temperatures and by including 16 mol% of cholesterol (Chol-OH) in the phospholipid bilayer. The DMPE-Glu-DTPA/Ln 3+ complex and the resulting assemblies are promising candidates for applications in numerous fields including pharmaceutical technologies, structural characterization of membrane biomolecules by NMR spectroscopy, as contrasting agents for magnetic resonance imaging, and for the development of smart optical gels.

  16. Phospholipid Homeostasis Regulates Dendrite Morphogenesis in Drosophila Sensory Neurons

    Directory of Open Access Journals (Sweden)

    Shan Meltzer

    2017-10-01

    Full Text Available Disruptions in lipid homeostasis have been observed in many neurodevelopmental disorders that are associated with dendrite morphogenesis defects. However, the molecular mechanisms of how lipid homeostasis affects dendrite morphogenesis are unclear. We find that easily shocked (eas, which encodes a kinase with a critical role in phospholipid phosphatidylethanolamine (PE synthesis, and two other enzymes in this synthesis pathway are required cell autonomously in sensory neurons for dendrite growth and stability. Furthermore, we show that the level of Sterol Regulatory Element-Binding Protein (SREBP activity is important for dendrite development. SREBP activity increases in eas mutants, and decreasing the level of SREBP and its transcriptional targets in eas mutants largely suppresses the dendrite growth defects. Furthermore, reducing Ca2+ influx in neurons of eas mutants ameliorates the dendrite morphogenesis defects. Our study uncovers a role for EAS kinase and reveals the in vivo function of phospholipid homeostasis in dendrite morphogenesis.

  17. Computational fluid dynamics modeling and analysis of Pd-based membrane module for CO{sub 2} capture from H{sub 2}/CO{sub 2} binary gas mixture

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Dong-Yoon; Park, Myung-June [Ajou University, Suwon (Korea, Republic of); Hwang, Kyung-Ran; Park, Jong-Soo [Korea Institute of Energy Research, Daejeon (Korea, Republic of)

    2015-07-15

    A Pd-based membrane module for the capture of CO{sub 2} from a H{sub 2}/CO{sub 2} binary gas mixture was considered, and computational fluid dynamics modeling was used to predict the module performance. Detailed models of momentum and mass balances, including local flux as a function of local linear velocity, satisfactorily described CO{sub 2} fraction in a retentate tube when compared to the experimental data under various feed flow rates. By using the model, several cases having different geometries, including the location and diameter of feed tube and the number and location of the feed and retentate tubes, were considered. Among tested geometries, the case of two feed tubes with each offset by an angle, θ, of 45° from the center line, and a feed tube diameter of 2.45mm showed the increase of the feed flow rate up to 11.80% compared to the reference case while a CO{sub 2} fraction of 90% in the retentate, which was the criterion for effective CO{sub 2} capture in the present study, was guaranteed. This would result in a plausible reduction in capital expenditures for the CO{sub 2} capture process.

  18. Differential intrahepatic phospholipid zonation in simple steatosis and nonalcoholic steatohepatitis.

    Directory of Open Access Journals (Sweden)

    Julia Wattacheril

    Full Text Available Nonalcoholic fatty liver disease (NAFLD occurs frequently in a setting of obesity, dyslipidemia and insulin resistance, but the etiology of the disease, particularly the events favoring progression to nonalcoholic steatohepatitis (NASH as opposed to simple steatosis (SS, are not fully understood. Based on known zonation patterns in protein, glucose and lipid metabolism, coupled with evidence that phosphatidylcholine may play a role in NASH pathogenesis, we hypothesized that phospholipid zonation exists in liver and that specific phospholipid abundance and distribution may be associated with histologic disease. A survey of normal hepatic protein expression profiles in the Human Protein Atlas revealed pronounced zonation of enzymes involved in lipid utilization and storage, particularly those facilitating phosphatidylcholine (PC metabolism. Immunohistochemistry of obese normal, SS and NASH liver specimens with anti-phosphatidylethanomine N-methyltransferase (PEMT antibodies showed a progressive decrease in the zonal distribution of this PC biosynthetic enzyme. Phospholipid quantitation by liquid chromatography mass spectrometry (LC-MS in hepatic extracts of Class III obese patients with increasing NAFLD severity revealed that most PC species with 32, 34 and 36 carbons as well as total PC abundance was decreased with SS and NASH. Matrix assisted laser desorption ionization-imaging mass spectrometry (MALDI-IMS imaging revealed strong zonal distributions for 32, 34 and 36 carbon PCs in controls (minimal histologic findings and SS that was lost in NASH specimens. Specific lipid species such as PC 34:1 and PC 36:2 best illustrated this phenomenon. These findings suggest that phospholipid zonation may be associated with the presence of an intrahepatic proinflammatory phenotype and thus have broad implications in the etiopathogenesis of NASH.

  19. The ELBA force field for coarse-grain modeling of lipid membranes.

    Directory of Open Access Journals (Sweden)

    Mario Orsi

    Full Text Available A new coarse-grain model for molecular dynamics simulation of lipid membranes is presented. Following a simple and conventional approach, lipid molecules are modeled by spherical sites, each representing a group of several atoms. In contrast to common coarse-grain methods, two original (interdependent features are here adopted. First, the main electrostatics are modeled explicitly by charges and dipoles, which interact realistically through a relative dielectric constant of unity (ε(r = 1. Second, water molecules are represented individually through a new parametrization of the simple Stockmayer potential for polar fluids; each water molecule is therefore described by a single spherical site embedded with a point dipole. The force field is shown to accurately reproduce the main physical properties of single-species phospholipid bilayers comprising dioleoylphosphatidylcholine (DOPC and dioleoylphosphatidylethanolamine (DOPE in the liquid crystal phase, as well as distearoylphosphatidylcholine (DSPC in the liquid crystal and gel phases. Insights are presented into fundamental properties and phenomena that can be difficult or impossible to study with alternative computational or experimental methods. For example, we investigate the internal pressure distribution, dipole potential, lipid diffusion, and spontaneous self-assembly. Simulations lasting up to 1.5 microseconds were conducted for systems of different sizes (128, 512 and 1058 lipids; this also allowed us to identify size-dependent artifacts that are expected to affect membrane simulations in general. Future extensions and applications are discussed, particularly in relation to the methodology's inherent multiscale capabilities.

  20. Nanoelectropulse-driven membrane perturbation and small molecule permeabilization

    Directory of Open Access Journals (Sweden)

    Sun Yinghua

    2006-10-01

    Full Text Available Abstract Background Nanosecond, megavolt-per-meter pulsed electric fields scramble membrane phospholipids, release intracellular calcium, and induce apoptosis. Flow cytometric and fluorescence microscopy evidence has associated phospholipid rearrangement directly with nanoelectropulse exposure and supports the hypothesis that the potential that develops across the lipid bilayer during an electric pulse drives phosphatidylserine (PS externalization. Results In this work we extend observations of cells exposed to electric pulses with 30 ns and 7 ns durations to still narrower pulse widths, and we find that even 3 ns pulses are sufficient to produce responses similar to those reported previously. We show here that in contrast to unipolar pulses, which perturb membrane phospholipid order, tracked with FM1-43 fluorescence, only at the anode side of the cell, bipolar pulses redistribute phospholipids at both the anode and cathode poles, consistent with migration of the anionic PS head group in the transmembrane field. In addition, we demonstrate that, as predicted by the membrane charging hypothesis, a train of shorter pulses requires higher fields to produce phospholipid scrambling comparable to that produced by a time-equivalent train of longer pulses (for a given applied field, 30, 4 ns pulses produce a weaker response than 4, 30 ns pulses. Finally, we show that influx of YO-PRO-1, a fluorescent dye used to detect early apoptosis and activation of the purinergic P2X7 receptor channels, is observed after exposure of Jurkat T lymphoblasts to sufficiently large numbers of pulses, suggesting that membrane poration occurs even with nanosecond pulses when the electric field is high enough. Propidium iodide entry, a traditional indicator of electroporation, occurs with even higher pulse counts. Conclusion Megavolt-per-meter electric pulses as short as 3 ns alter the structure of the plasma membrane and permeabilize the cell to small molecules. The dose

  1. Hybrid electrospun chitosan-phospholipids nanofibers for transdermal drug delivery.

    Science.gov (United States)

    Mendes, Ana C; Gorzelanny, Christian; Halter, Natalia; Schneider, Stefan W; Chronakis, Ioannis S

    2016-08-20

    Chitosan (Ch) polysaccharide was mixed with phospholipids (P) to generate electrospun hybrid nanofibers intended to be used as platforms for transdermal drug delivery. Ch/P nanofibers exibithed average diameters ranging from 248±94nm to 600±201nm, depending on the amount of phospholipids used. Fourier Transformed Infra-Red (FTIR) spectroscopy and Dynamic Light Scattering (DLS) data suggested the occurrence of electrostatic interactions between amine groups of chitosan with the phospholipid counterparts. The nanofibers were shown to be stable for at least 7days in Phosphate Buffer Saline (PBS) solution. Cytotoxicity studies (WST-1 and LDH assays) demonstrated that the hybrid nanofibers have suitable biocompatibility. Fluorescence microscopy, also suggested that L929 cells seeded on top of the CH/P hybrid have similar metabolic activity comparatively to the cells seeded on tissue culture plate (control). The release of curcumin, diclofenac and vitamin B12, as model drugs, from Ch/P hybrid nanofibers was investigated, demonstrating their potential utilization as a transdermal drug delivery system. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Increased Anti-Phospholipid Antibodies in Autism Spectrum Disorders

    Directory of Open Access Journals (Sweden)

    Milo Careaga

    2013-01-01

    Full Text Available Autism spectrum disorders (ASD are characterized by impairments in communication, social interactions, and repetitive behaviors. While the etiology of ASD is complex and likely involves the interplay of genetic and environmental factors, growing evidence suggests that immune dysfunction and the presence of autoimmune responses including autoantibodies may play a role in ASD. Anti-phospholipid antibodies are believed to occur from both genetic and environmental factors and have been linked to a number of neuropsychiatric symptoms such as cognitive impairments, anxiety, and repetitive behaviors. In the current study, we investigated whether there were elevated levels of anti-phospholipid antibodies in a cross-sectional analysis of plasma of young children with ASD compared to age-matched typically developing (TD controls and children with developmental delays (DD other than ASD. We found that levels of anti-cardiolipin, β2-glycoprotein 1, and anti-phosphoserine antibodies were elevated in children with ASD compared with age-matched TD and DD controls. Further, the increase in antibody levels was associated with more impaired behaviors reported by parents. This study provides the first evidence for elevated production of anti-phospholipid antibodies in young children with ASD and provides a unique avenue for future research into determining possible pathogenic mechanisms that may underlie some cases of ASD.

  3. Phospholipid analogue distributions of Iranian isolates of candida

    International Nuclear Information System (INIS)

    Zarei Mahmoudabadi, A.; Brucker, D.B.

    2004-01-01

    The aim of this study was to analyse polar lipids of candida species isolated from Ahwas (Iran) by fast Atom bombardment mass spectrometry . Nine isolates of Candida Sp. were identified by growth at 45 d ig c , production of chlamydoconidia on cornmeal agar, colonial colour on CHROMagar Candida, germ tube production and ID 32 C kits. Then polar lipids were extracted from freeze-dried cultures and analysed using Fast Atom Bombardment Mass Spectrometry. The most intense carboxylate and phospholipid molecular species anions were of m/z 281 (C 1 8 : 1 ) and m/z 515 (PA 23:2). However, the most intense carboxylate and phospholipid analogues in Candida Parapsilosis were 292 (Un) and 555 (PA 26:3), which differed from other yeasts. Isolates were grouped by single linkage clustering based on correlation coefficient for strain pairs calculated with carboxylate and phospholipid molecular species distributions. Fast Atom Bombardment Mass Spectrometry can differentiate the C. albicans based on analysis of polar lipid distributions.These findings support that differentiation between C. albicans and other species is possible based on polar lipids

  4. The interaction of MRI contrast agents with phospholipids

    International Nuclear Information System (INIS)

    Jendrasiak, Gordon L.; Smith, Ralph L.; Ribeiro, Anthony A.

    2000-01-01

    The molecular interactions of three clinically used MRI contrast agents with lipid vesicles, consisting of egg phosphatidylcholine (EPC), have been studied using high-field NMR techniques. At a molar ratio of one contrast agent molecule to five phospholipid molecules, a significant increase in the proton resonance line width occurred for certain lipid head group moieties. A large decrease in the T 1 relaxation times for the head group moieties was also observed. These two effects occurred regardless of the ionic status and the chelate structure of the three contrast agents. The structure of the contrast agents did, however, affect the magnitude of the two NMR parameter changes. These NMR effects also differed in magnitude amongst the various head group entities. The NMR effects were greatest for the head group moieties at or near the vesicle-water interface. The results are discussed in terms of the structure of the phospholipid-water interface. Since the use of contrast agents has become routine in clinical MRI, our results are of importance in terms of the interaction of the agents with physiological surfaces, many of which contain phospholipids. The understanding of such interactions should be of value not only for improved diagnostics, but also in the development of new contrast agents. (author)

  5. Protein-membrane interaction and fatty acid transfer from intestinal fatty acid-binding protein to membranes. Support for a multistep process.

    Science.gov (United States)

    Falomir-Lockhart, Lisandro J; Laborde, Lisandro; Kahn, Peter C; Storch, Judith; Córsico, Betina

    2006-05-19

    Fatty acid transfer from intestinal fatty acid-binding protein (IFABP) to phospholipid membranes occurs during protein-membrane collisions. Electrostatic interactions involving the alpha-helical "portal" region of the protein have been shown to be of great importance. In the present study, the role of specific lysine residues in the alpha-helical region of IFABP was directly examined. A series of point mutants in rat IFABP was engineered in which the lysine positive charges in this domain were eliminated or reversed. Using a fluorescence resonance energy transfer assay, we analyzed the rates and mechanism of fatty acid transfer from wild type and mutant proteins to acceptor membranes. Most of the alpha-helical domain mutants showed slower absolute fatty acid transfer rates to zwitterionic membranes, with substitution of one of the lysines of the alpha2 helix, Lys27, resulting in a particularly dramatic decrease in the fatty acid transfer rate. Sensitivity to negatively charged phospholipid membranes was also reduced, with charge reversal mutants in the alpha2 helix the most affected. The results support the hypothesis that the portal region undergoes a conformational change during protein-membrane interaction, which leads to release of the bound fatty acid to the membrane and that the alpha2 segment is of particular importance in the establishment of charge-charge interactions between IFABP and membranes. Cross-linking experiments with a phospholipid-photoactivable reagent underscored the importance of charge-charge interactions, showing that the physical interaction between wild-type intestinal fatty acid-binding protein and phospholipid membranes is enhanced by electrostatic interactions. Protein-membrane interactions were also found to be enhanced by the presence of ligand, suggesting different collisional complex structures for holo- and apo-IFABP.

  6. Impact of Lipid Oxidization on Vertical Structures and Electrostatics of Phospholipid Monolayers Revealed by Combination of Specular X-ray Reflectivity and Grazing-Incidence X-ray Fluorescence.

    Science.gov (United States)

    Korytowski, Agatha; Abuillan, Wasim; Makky, Ali; Konovalov, Oleg; Tanaka, Motomu

    2015-07-30

    The influence of phospholipid oxidization of floating monolayers on the structure perpendicular to the global plane and on the density profiles of ions near the lipid monolayer has been investigated by a combination of grazing incidence X-ray fluorescence (GIXF) and specular X-ray reflectivity (XRR). Systematic variation of the composition of the floating monolayers unravels changes in the thickness, roughness and electron density of the lipid monolayers as a function of molar fraction of oxidized phospholipids. Simultaneous GIXF measurements enable one to qualitatively determine the element-specific density profiles of monovalent (K(+) or Cs(+)) and divalent ions (Ca(2+)) in the vicinity of the interface in the presence and absence of two types of oxidized phospholipids (PazePC and PoxnoPC) with high spatial accuracy (±5 Å). We found the condensation of Ca(2+) near carboxylated PazePC was more pronounced compared to PoxnoPC with an aldehyde group. In contrast, the condensation of monovalent ions could hardly be detected even for pure oxidized phospholipid monolayers. Moreover, pure phospholipid monolayers exhibited almost no ion specific condensation near the interface. The quantitative studies with well-defined floating monolayers revealed how the elevation of lipid oxidization level alters the structures and functions of cell membranes.

  7. Current-Induced Membrane Discharge

    DEFF Research Database (Denmark)

    Andersen, Mathias Bækbo; van Soestbergen, M.; Mani, A.

    2012-01-01

    . Salt depletion leads to a large electric field resulting in a local pH shift within the membrane with the effect that the membrane discharges and loses its ion selectivity. Since salt co-ions, H+ ions, and OH- ions contribute to OLC, CIMD interferes with electrodialysis (salt counterion removal...... neglects chemical effects and remains to be quantitatively tested. Here, we show that charge regulation and water self-ionization can lead to OLC by "current-induced membrane discharge'' (CIMD), even in the absence of fluid flow, in ion-exchange membranes much thicker than the local Debye screening length...

  8. Effect of phospholipid deposits on adhesion of bacteria to contact lenses.

    Science.gov (United States)

    Babaei Omali, Negar; Proschogo, Nicholas; Zhu, Hua; Zhao, Zhenjun; Diec, Jennie; Borazjani, Roya; Willcox, Mark D P

    2012-01-01

    Protein and lipid deposits on contact lenses may contribute to clinical complications. This study examined the effect of phospholipids on the adhesion of bacteria to contact lenses. Worn balafilcon A (n = 11) and senofilcon A (n = 11) were collected after daily wear and phospholipids were extracted in chloroform:methanol. The amount of phospholipid was measured by electrospray ionization mass spectrometry. Unworn lenses soaked in phospholipids were exposed to Pseudomonas aeruginosa and Staphylococcus aureus. After 18 h incubation, the numbers of P. aeruginosa or S. aureus that adhered to the lenses were measured. Phospholipid was tested for possible effects on bacterial growth. A broad range of sphingomyelins (SM) and phosphatidylcholines (PC) were detected from both types of worn lenses. SM (16:0) (m/z 703) and PC (34:2) (m/z 758) were the major phospholipids detected in the lens extracts. Phospholipids did not alter the adhesion of any strain of P. aeruginosa or S. aureus (p > 0.05). Phospholipids (0.1 mg/mL) showed no effect on the growth of P. aeruginosa 6294 or S. aureus 031. Phospholipids adsorb/absorb to contact lenses during wear, however, the major types of phospholipids adsorbed to lenses do not alter bacterial adhesion or growth.

  9. Membrane fusion

    DEFF Research Database (Denmark)

    Bendix, Pól Martin

    2015-01-01

    At Stanford University, Boxer lab, I worked on membrane fusion of small unilamellar lipid vesicles to flat membranes tethered to glass surfaces. This geometry closely resembles biological systems in which liposomes fuse to plasma membranes. The fusion mechanism was studied using DNA zippering...... between complementary strands linked to the two apposing membranes closely mimicking the zippering mechanism of SNARE fusion complexes....

  10. Nanoparticle self-assembly in mixtures of phospholipids with styrene/maleic acid copolymers or fluorinated surfactants

    Science.gov (United States)

    Vargas, Carolyn; Arenas, Rodrigo Cuevas; Frotscher, Erik; Keller, Sandro

    2015-12-01

    Self-assembling nanostructures in aqueous mixtures of bilayer-forming lipids and micelle-forming surfactants are relevant to in vitro studies on biological and synthetic membranes and membrane proteins. Considerable efforts are currently underway to replace conventional detergents by milder alternatives such as styrene/maleic acid (SMA) copolymers and fluorinated surfactants. However, these compounds and their nanosized assemblies remain poorly understood as regards their interactions with lipid membranes, particularly, the thermodynamics of membrane partitioning and solubilisation. Using 19F and 31P nuclear magnetic resonance spectroscopy, static and dynamic light scattering, and isothermal titration calorimetry, we have systematically investigated the aggregational state of a zwitterionic bilayer-forming phospholipid upon exposure to an SMA polymer with a styrene/maleic acid ratio of 3 : 1 or to a fluorinated octyl phosphocholine derivative called F6OPC. The lipid interactions of SMA(3 : 1) and F6OPC can be thermodynamically conceptualised within the framework of a three-stage model that treats bilayer vesicles, discoidal or micellar nanostructures, and the aqueous solution as distinct pseudophases. The exceptional solubilising power of SMA(3 : 1) is reflected in very low membrane-saturating and solubilising polymer/lipid molar ratios of 0.10 and 0.15, respectively. Although F6OPC saturates bilayers at an even lower molar ratio of 0.031, this nondetergent does not solubilise lipids even at >1000-fold molar excess, thus highlighting fundamental differences between these two types of mild membrane-mimetic systems. We rationalise these findings in terms of a new classification of surfactants based on bilayer-to-micelle transfer free energies and discuss practical implications for membrane-protein research.Self-assembling nanostructures in aqueous mixtures of bilayer-forming lipids and micelle-forming surfactants are relevant to in vitro studies on biological and

  11. Interaction of blood coagulation factor Va with phospholipid vesicles examined by using lipophilic photoreagents

    International Nuclear Information System (INIS)

    Krieg, U.C.; Isaacs, B.S.; Yemul, S.S.; Esmon, C.T.; Bayley, H.; Johnson, A.E.

    1987-01-01

    Two different lipophilic photoreagents, [ 3 H]adamantane diazirine and 3-(trifluoromethyl)-3-(m-[ 125 I]iodophenyl)diazirine (TID), have been utilized to examine the interactions of blood coagulation factor Va with calcium, prothrombin, factor Xa, and, in particular, phospholipid vesicles. With each of these structurally dissimilar reagents, the extent of photolabeling of factor Va was greater when the protein was bound to a membrane surface than when it was free in solution. Specifically, the covalent photoreaction with Vl, the smaller subunit of factor Va, was 2-fold higher in the presence of phosphatidylcholine/phosphatidylserine (PC/PS, 3:1) vesicles, to which factor Va binds, than in the presence of 100% PC vesicles, to which the protein does not bind. However, the magnitude of the PC/PS-dependent photolabeling was much less than has been observed previously with integral membrane proteins. It therefore appears that the binding of factor Va to the membrane surface exposes Vl to the lipid core of the bilayer, but that only a small portion of the Vl polypeptide is exposed to, or embedded in, the bilayer core. Addition of either prothrombin or active-site-blocked factor Xa to PC/PS-bound factor Va had little effect on the photolabeling of Vl with TID, but reduced substantially the covalent labeling of Vh, the larger subunit of factor Va. This indicates that prothrombin and factor Xa each cover nonpolar surfaces on Vh when the macromolecules associate on the PC/PS surface. It therefore seems likely that the formation of the prothrombinase complex involves a direct interaction between Vh and factor Xa and between Vh and prothrombin.(ABSTRACT TRUNCATED AT 250 WORDS)

  12. Application of biomimetic HPLC to estimate lipophilicity, protein and phospholipid binding of potential peptide therapeutics

    Directory of Open Access Journals (Sweden)

    Klara Livia Valko

    2018-06-01

    Full Text Available Peptide therapeutics are new modalities offering several challenges to drug discovery. They are generally less stable and permeable in vivo. The characterization of their lipophilicity cannot be carried out using the traditional in silico or wet octanol/water partition coefficients. The prediction of their in vivo distribution and permeability is also challenging. In this paper, it is demonstrated that the biomimetic properties such as lipophilicity, protein and phospholipid binding can be easily assessed by HPLC using chemically bonded protein and immobilized artificial membrane (IAM stationary phases. The obtained properties for a set of potential therapeutic peptides with 3 to 33 amino acids have been analysed and it was found that similar characteristics of the properties could be observed as for small molecule drugs. The albumin binding showed correlation with their measured lipophilicity on the C-18 stationary phase with acidic peptides showing stronger than expected albumin binding. The (IAM chromatography revealed peptide membrane affinity, which was stronger for positively charged peptides (containing arginine and showed correlation to the alpha-1-acid glycoprotein (AGP binding, which was also stronger for positively charged compounds. The in vivo volume of distribution and drug efficiency of the peptides have been estimated using the models developed for small molecules. One of the candidate linear peptides has been assessed in various cellular and in vivo assays and the results have confirmed the estimated cell partition and brain to plasma ratio. It can be demonstrated, that up to 21 amino acids, the peaks of the peptides obtained on the protein phase were symmetrical and narrow. The interaction of larger peptides with the protein stationary phases resulted in wide peaks showing multiple equilibrium processes with slow kinetics during chromatography. The larger peptides showed narrow and symmetrical peaks on the IAM column enabling

  13. Fouling resistant membrane spacers

    KAUST Repository

    Ghaffour, Noreddine

    2017-10-12

    Disclosed herein are spacers having baffle designs and perforations for efficiently and effectively separating one or more membrane layers a membrane filtration system. The spacer (504) includes a body (524) formed at least in part by baffles (520) that are interconnected, and the baffles define boundaries of openings or apertures (525) through a thickness direction of the body of the spacer. Alternatively or additionally, passages or perforations (526A, 526B) may be present in the spacer layer or baffles for fluid flow there through, with the passages and baffles having a numerous different shapes and sizes.

  14. SCS3 and YFT2 link transcription of phospholipid biosynthetic genes to ER stress and the UPR.

    Directory of Open Access Journals (Sweden)

    Robyn D Moir

    2012-08-01

    Full Text Available The ability to store nutrients in lipid droplets (LDs is an ancient function that provides the primary source of metabolic energy during periods of nutrient insufficiency and between meals. The Fat storage-Inducing Transmembrane (FIT proteins are conserved ER-resident proteins that facilitate fat storage by partitioning energy-rich triglycerides into LDs. FIT2, the ancient ortholog of the FIT gene family first identified in mammals has two homologs in Saccharomyces cerevisiae (SCS3 and YFT2 and other fungi of the Saccharomycotina lineage. Despite the coevolution of these genes for more than 170 million years and their divergence from higher eukaryotes, SCS3, YFT2, and the human FIT2 gene retain some common functions: expression of the yeast genes in a human embryonic kidney cell line promotes LD formation, and expression of human FIT2 in yeast rescues the inositol auxotrophy and chemical and genetic phenotypes of strains lacking SCS3. To better understand the function of SCS3 and YFT2, we investigated the chemical sensitivities of strains deleted for either or both genes and identified synthetic genetic interactions against the viable yeast gene-deletion collection. We show that SCS3 and YFT2 have shared and unique functions that connect major biosynthetic processes critical for cell growth. These include lipid metabolism, vesicular trafficking, transcription of phospholipid biosynthetic genes, and protein synthesis. The genetic data indicate that optimal strain fitness requires a balance between phospholipid synthesis and protein synthesis and that deletion of SCS3 and YFT2 impacts a regulatory mechanism that coordinates these processes. Part of this mechanism involves a role for SCS3 in communicating changes in the ER (e.g. due to low inositol to Opi1-regulated transcription of phospholipid biosynthetic genes. We conclude that SCS3 and YFT2 are required for normal ER membrane biosynthesis in response to perturbations in lipid metabolism and ER

  15. Effect of Different Phospholipids on α-Secretase Activity in the Non-Amyloidogenic Pathway of Alzheimer’s Disease

    Science.gov (United States)

    Grimm, Marcus O. W.; Haupenthal, Viola J.; Rothhaar, Tatjana L.; Zimmer, Valerie C.; Grösgen, Sven; Hundsdörfer, Benjamin; Lehmann, Johannes; Grimm, Heike S.; Hartmann, Tobias

    2013-01-01

    Alzheimer’s disease (AD) is characterized by extracellular accumulation of amyloid-β peptide (Aβ), generated by proteolytic processing of the amyloid precursor protein (APP) by β- and γ-secretase. Aβ generation is inhibited when the initial ectodomain shedding is caused by α-secretase, cleaving APP within the Aβ domain. Therefore, an increase in α-secretase activity is an attractive therapeutic target for AD treatment. APP and the APP-cleaving secretases are all transmembrane proteins, thus local membrane lipid composition is proposed to influence APP processing. Although several studies have focused on γ-secretase, the effect of the membrane lipid microenvironment on α-secretase is poorly understood. In the present study, we systematically investigated the effect of fatty acid (FA) acyl chain length (10:0, 12:0, 14:0, 16:0, 18:0, 20:0, 22:0, 24:0), membrane polar lipid headgroup (phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine), saturation grade and the FA double-bond position on α-secretase activity. We found that α-secretase activity is significantly elevated in the presence of FAs with short chain length and in the presence of polyunsaturated FAs, whereas variations in the phospholipid headgroups, as well as the double-bond position, have little or no effect on α-secretase activity. Overall, our study shows that local lipid membrane composition can influence α-secretase activity and might have beneficial effects for AD. PMID:23485990

  16. Fluid Mechanics.

    Science.gov (United States)

    Drazin, Philip

    1987-01-01

    Outlines the contents of Volume II of "Principia" by Sir Isaac Newton. Reviews the contributions of subsequent scientists to the physics of fluid dynamics. Discusses the treatment of fluid mechanics in physics curricula. Highlights a few of the problems of modern research in fluid dynamics. Shows that problems still remain. (CW)

  17. Drying of supercritical carbon dioxide with membrane processes

    NARCIS (Netherlands)

    Lohaus, Theresa; Scholz, Marco; Koziara, Beata; Benes, Nieck Edwin; Wessling, Matthias

    2015-01-01

    In supercritical extraction processes regenerating the supercritical fluid represents the main cost constraint. Membrane technology has potential for cost efficient regeneration of water-loaded supercritical carbon dioxide. In this study we have designed membrane-based processes to dehydrate

  18. Free and membrane-bound calcium in microgravity and microgravity effects at the membrane level

    Science.gov (United States)

    Belyavskaya, N. A.

    The changes of [Ca^2+]_i controlled is known to play a key regulatory role in numerous cellular processes especially associated with membranes. Previous studies from our laboratory have demonstrated an increase in calcium level in root cells of pea seedlings grown aboard orbital station ``Salyut 6'' /1/. These results: 1) indicate that observed Ca^2+-binding sites of membranes also consist in proteins and phospholipids; 2) suggest that such effects of space flight in membrane Ca-binding might be due to the enhancement of Ca^2+ influx through membranes. In model presented, I propose that Ca^2+-activated channels in plasma membrane in response to microgravity allow the movement of Ca^2+ into the root cells, causing a rise in cytoplasmic free Ca^2+ levels. The latter, in its turn, may induce the inhibition of a Ca^2+ efflux by Ca^2+-activated ATPases and through a Ca^2+/H^+ antiport. It is possible that increased cytosolic levels of Ca^2+ ions have stimulated hydrolysis and turnover of phosphatidylinositols, with a consequent elevation of cytosolic [Ca^2+]_i. Plant cell can response to such a Ca^2+ rise by an enhancement of membranous Ca^2+-binding activities to rescue thus a cell from an abundance of a cytotoxin. A Ca^2+-induced phase separation of membranous lipids assists to appear the structure nonstable zones with high energy level at the boundary of microdomains which are rich by some phospholipid components; there is mixing of molecules of the membranes contacted in these zones, the first stage of membranous fusion, which was found in plants exposed to microgravity. These results support the hypothesis that a target for microgravity effect is the flux mechanism of Ca^2+ to plant cell.

  19. Understanding Detergent Effects on Lipid Membranes: A Model Study of Lysolipids

    DEFF Research Database (Denmark)

    Henriksen, Jonas Rosager; Andresen, Thomas Lars; Feldborg, Lise Nørkjær

    2010-01-01

    Lysolipids and fatty acids are the natural products formed by the hydrolysis of phospholipids. Lysolipids and fatty acids form micelles in solution and acts as detergents in the presence of lipid membranes. In this study, we investigate the detergent strength of a homologous series of lyso......-chain mismatch between LPC and POPC determines the magnitude of the membrane mechanical perturbation per LPC molecule in the membrane. Finally, the three-stage model describing detergent membrane interaction has been extended by a parameter D-MCI, which governs the membrane curvature stability in the detergent...

  20. Synaptic Membrane Synthesis in Rats Depends on Dietary Sufficiency of Vitamin C, Vitamin E, and Selenium: Relevance for Alzheimer's Disease.

    Science.gov (United States)

    Cansev, Mehmet; Turkyilmaz, Mesut; Sijben, John W C; Sevinc, Cansu; Broersen, Laus M; van Wijk, Nick

    2017-01-01

    Chronic consumption of a diet enriched with nutritional precursors of phospholipids, including uridine and the polyunsaturated fatty acids, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), was shown previously to enhance levels of brain phospholipids and synaptic proteins in rodents. Vitamin C, vitamin E, and selenium may directly affect the breakdown or synthesis of membrane phospholipids. The present study investigated the necessity of antioxidants for the effectiveness of supplementation with uridine plus DHA and EPA (as fish oil) in rats. Rats were randomized to four treatment groups and received, for 6 weeks, one of four experimental diets, i.e., a diet low in antioxidants, a diet high in antioxidants, a diet low in antioxidants supplemented with DHA+EPA+uridine, or a diet high in antioxidants supplemented with DHA+EPA+uridine. On completion of dietary treatment, rats were sacrificed, and brain levels of phospholipids, synaptic proteins, and two enzymes involved in phospholipid synthesis (choline-phosphate cytidylyltransferase, PCYT1A, and choline/ethanolamine phosphotransferase, CEPT1) were analyzed. Levels of phospholipids, the pre- and post-synaptic proteins Synapsin-1 and PSD95, and the enzymes PCYT1A and CEPT1 were significantly enhanced by combined supplementation of DHA+EPA+uridine and antioxidants and not enhanced by supplementation of DHA+EPA+uridine with insufficient antioxidant levels. Our data suggest that dietary vitamin C, vitamin E, and selenium are essential for the phospholipid precursors' effects on increasing levels of membrane phospholipids and synaptic proteins, the indirect indicators of synaptogenesis. Their concomitant supply may be relevant in Alzheimer's disease patients, because the disease is characterized by synapse loss and lower plasma and brain levels of phospholipid precursors and antioxidants.

  1. Efficient discrimination and removal of phospholipids during electromembrane extraction from human plasma samples

    DEFF Research Database (Denmark)

    Vårdal, Linda; Gjelstad, Astrid; Huang, Chuixiu

    2017-01-01

    to be highly efficient for providing phospholipid-free extracts. CONCLUSION: Ultra-HPLC-MS/MS analysis of the donor solutions revealed that the phospholipids principally remained in the plasma samples. This proved that the phospholipids did not migrate in the electrical field and they were prevented from......AIM: For the first time, extracts obtained from human plasma samples by electromembrane extraction (EME) were investigated comprehensively with particular respect to phospholipids using ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). Thhe purpose...

  2. A retrospective: Use of Escherichia coli as a vehicle to study phospholipid synthesis and function

    Science.gov (United States)

    Dowhan, William

    2012-01-01

    Although the study of individual phospholipids and their synthesis began in the 1920’s first in plants and then mammals, it was not until the early 1960’s that Eugene Kennedy using Escherichia coli initiated studies of bacterial phospholipid metabolism. With the base of information already available from studies of mammalian tissue, the basic blueprint of phospholipid biosynthesis in E. coli was worked out by the late 1960’s. In 1970’s and 1980’s most of the enzymes responsible for phospholipid biosynthesis were purified and many of the genes encoding these enzymes were identified. By the late 1990’s conditional and null mutants were available along with clones of the genes for every step of phospholipid biosynthesis. Most of these genes had been sequenced before the complete E. coli genome sequence was available. Strains of E. coli were developed in which phospholipid composition could be changed in a systematic manner while maintaining cell viability. Null mutants, strains in which phospholipid metabolism was artificially regulated, and strains synthesizing foreign lipids not found in E. coli have been used to this day to define specific roles for individual phospholipid. This review will trace the findings that have led to the development of E. coli as an excellent model system to study mechanisms underlying the synthesis and function of phospholipids that are widely applicable to other prokaryotic and eukaryotic systems. PMID:22925633

  3. Measurement of total phospholipids in urine of patients treated with gentamicin.

    Science.gov (United States)

    Saunders, D A; Begg, E J; Kirkpatrick, C M; Yeo, J; Graham, G G; Bailey, R R

    1997-04-01

    The excretion of phospholipids in urine may be a marker of the early renal toxicity of the aminoglycoside antibiotics. Urinary phospholipids are formed in myeloid bodies which develop in the lysosomes of proximal tubules during treatment with the aminoglycosides, and overflow into the urine. Published assays were modified in order to measure the total phospholipid concentrations in human urine. Phospholipids were extracted from freeze-dried urine samples, digested in concentrated sulphuric acid, and the inorganic phosphorus content determined by complexing with ammonium molybdate and measuring the absorbance at 820 nm. Ten septicaemic patients treated with gentamicin for 5-7 days had significantly higher urine phospholipid concentrations than 10 healthy untreated control subjects (P < 0.0001). There was a negative linear relationship between phospholipid excretion and creatinine clearance (r2 = 0.71). In 34 patients with acute pyelonephritis, increased phospholipid concentrations were observed prior to treatment compared with healthy controls (P < 0.001) and did not alter during treatment with gentamicin. However, the phospholipid concentrations decreased significantly after treatment was completed (P < 0.03). These studies suggest that urinary phospholipids may indicate early aminoglycoside toxicity but with poor specificity, as many of the infections being treated may themselves be associated with phospholipiduria.

  4. Lipophilic drug transfer between liposomal and biological membranes

    DEFF Research Database (Denmark)

    Fahr, Alfred; van Hoogevest, Peter; Kuntsche, Judith

    2006-01-01

    This review presents the current knowledge on the interaction of lipophilic, poorly water soluble drugs with liposomal and biological membranes. The center of attention will be on drugs having the potential to dissolve in a lipid membrane without perturbing them too much. The degree of interaction...... is described as solubility of a drug in phospholipid membranes and the kinetics of transfer of a lipophilic drug between membranes. Finally, the consequences of these two factors on the design of lipid-based carriers for oral, as well as parenteral use, for lipophilic drugs and lead selection of oral...... lipophilic drugs is described. Since liposomes serve as model-membranes for natural membranes, the assessment of lipid solubility and transfer kinetics of lipophilic drug using liposome formulations may additionally have predictive value for bioavailability and biodistribution and the pharmacokinetics...

  5. [Modification of retinal photoreceptor membranes and Ca ion binding].

    Science.gov (United States)

    Korchagin, V P; Berman, A L; Shukoliukov, S A; Rychkova, M P; Etingof, R N

    1978-10-01

    Calcium binding by modified photoreceptor membranes of cattle retina has been studied. Ca2+-binding the membranes significantly changes after C-phospholipase treatment, displaying the initial growth (less than 65% of lipid phosphorus removed) with subsequent decrease (more than 65% of phosphorus removed). Liposomes of the photoreceptor membranes lipids were found to bind more calcium than do the native photoreceptor membranes. Proteolytic enzymes (papaine, pronase) splitting some rhodopsin fragments do not affect the ability of the membrane to bind Ca2+. The increase of light-induced Ca-binding is observed only after the outer segments preincubation under conditions providing for rhodopsin phosphorylation. This effect was observed also after the splitting of the rhodopsin fragment by papaine. It is concluded that calcium binding in the photoreceptor membranes is mainly due to the phosphate groups of phospholipids.

  6. Equation of State for Phospholipid Self-Assembly

    DEFF Research Database (Denmark)

    Marsh, Derek

    2016-01-01

    Phospholipid self-assembly is the basis of biomembrane stability. The entropy of transfer from water to self-assembled micelles of lysophosphatidylcholines and diacyl phosphatidylcholines with different chain lengths converges to a common value at a temperature of 44°C. The corresponding enthalpies...... of transfer converge at ∼-18°C. An equation of state for the free energy of self-assembly formulated from this thermodynamic data depends on the heat capacity of transfer as the sole parameter needed to specify a particular lipid. For lipids lacking calorimetric data, measurement of the critical micelle...

  7. Accumulation of macular xanthophylls in unsaturated membrane domains.

    Science.gov (United States)

    Wisniewska, Anna; Subczynski, Witold K

    2006-05-15

    The distribution of macular xanthophylls, lutein and zeaxanthin, between domains formed in membranes made from an equimolar ternary mixture of dioleoylphosphatidylcholine/sphingomyelin/cholesterol, called a raft-forming mixture, was investigated. In these membranes, two domains are formed: the raft domain enriched in saturated lipids and cholesterol (detergent-resistant membranes, DRM), and the bulk domain enriched in unsaturated lipids (detergent-soluble membranes, DSM). These membrane domains have been separated using cold Triton X-100 extraction from membranes containing 1 mol% of either lutein or zeaxanthin. The results indicated that xanthophylls are substantially excluded from DRM and remain concentrated in DSM. Concentrations of xanthophylls in DRM and DSM calculated as the mole ratio of either xanthophyll to phospholipid were 0.005 and 0.03, respectively, and calculated as the mole ratio of either xanthophyll to total lipid (phospholipid + cholesterol) were 0.003 and 0.025, respectively. Thus, xanthophylls are over eight times more concentrated in DSM than in DRM. No significant difference in the distribution of lutein and zeaxanthin was found. It was also demonstrated using saturation-recovery EPR that at 1 mol%, neither lutein nor zeaxanthin affect the formation of membrane domains. The location of xanthophylls in domains formed from unsaturated lipids is ideal if they are to act as a lipid antioxidant, which is the most accepted mechanism through which lutein and zeaxanthin protect the retina from age-related macular diseases.

  8. Composite perfluorohydrocarbon membranes, their preparation and use

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Yong; Bikson, Benjamin

    2017-04-04

    Composite porous hydrophobic membranes are prepared by forming a perfluorohydrocarbon layer on the surface of a preformed porous polymeric substrate. The substrate can be formed from poly (aryl ether ketone) and a perfluorohydrocarbon layer can be chemically grafted to the surface of the substrate. The membranes can be utilized for a broad range of fluid separations, such as microfiltration, nanofiltration, ultrafiltration as membrane contactors for membrane distillation and for degassing and dewatering of fluids. The membranes can further contain a dense ultra-thin perfluorohydrocarbon layer superimposed on the porous poly (aryl ether ketone) substrate and can be utilized as membrane contactors or as gas separation. membranes for natural gas treatment and gas dehydration.

  9. Characterising antimicrobial protein-membrane complexes

    International Nuclear Information System (INIS)

    Xun, Gloria; Dingley, Andrew; Tremouilhac, Pierre

    2009-01-01

    Full text: Antimicrobial proteins (AMPs) are host defence molecules that protect organisms from microbial infection. A number of hypotheses for AMP activity have been proposed which involve protein membrane interactions. However, there is a paucity of information describing AMP-membrane complexes in detail. The aim of this project is to characterise the interactions of amoebapore-A (APA-1) with membrane models using primarily solution-state NMR spectroscopy. APA-1 is an AMP which is regulated by a pH-dependent dimerisation event. Based on the atomic resolution solution structure of monomeric APA-1, it is proposed that this dimerisation is a prerequisite for ring-like hexameric pore formation. Due to the cytotoxicity of APA-1, we have developed a cell-free system to produce this protein. To facilitate our studies, we have adapted the cell-free system to isotope label APA-1. 13 C /15 N -enriched APA-1 sample was achieved and we have begun characterising APA-1 dimerisation and membrane interactions using NMR spectroscopy and other biochemical/biophysical methods. Neutron reflectometry is a surface-sensitive technique and therefore represents an ideal technique to probe how APA-1 interacts with membranes at the molecular level under different physiological conditions. Using Platypus, the pH-induced APA-1-membrane interactions should be detectable as an increase of the amount of protein adsorbed at the membrane surface and changes in the membrane properties. Specifically, detailed information of the structure and dimensions of the protein-membrane complex, the position and amount of the protein in the membrane, and the perturbation of the membrane phospholipids on protein incorporation can be extracted from the neutron reflectometry measurement. Such information will enable critical assessment of current proposed mechanisms of AMP activity in bacterial membranes and complement our NMR studies

  10. Fluids engineering

    International Nuclear Information System (INIS)

    Anon.

    1991-01-01

    Fluids engineering has played an important role in many applications, from ancient flood control to the design of high-speed compact turbomachinery. New applications of fluids engineering, such as in high-technology materials processing, biotechnology, and advanced combustion systems, have kept up unwaining interest in the subject. More accurate and sophisticated computational and measurement techniques are also constantly being developed and refined. On a more fundamental level, nonlinear dynamics and chaotic behavior of fluid flow are no longer an intellectual curiosity and fluid engineers are increasingly interested in finding practical applications for these emerging sciences. Applications of fluid technology to new areas, as well as the need to improve the design and to enhance the flexibility and reliability of flow-related machines and devices will continue to spur interest in fluids engineering. The objectives of the present seminar were: to exchange current information on arts, science, and technology of fluids engineering; to promote scientific cooperation between the fluids engineering communities of both nations, and to provide an opportunity for the participants and their colleagues to explore possible joint research programs in topics of high priority and mutual interest to both countries. The Seminar provided an excellent forum for reviewing the current state and future needs of fluids engineering for the two nations. With the Seminar ear-marking the first formal scientific exchange between Korea and the United States in the area of fluids engineering, the scope was deliberately left broad and general

  11. Docosahexaenoic (DHA modulates phospholipid-hydroperoxide glutathione peroxidase (Gpx4 gene expression to ensure self-protection from oxidative damage in hippocampal cells

    Directory of Open Access Journals (Sweden)

    Veronica eCasañas-Sanchez

    2015-07-01

    Full Text Available Docosahexaenoic acid (DHA, 22:6n-3 is a unique polyunsaturated fatty acid particularly abundant in nerve cell membrane phospholipids. DHA is a pleiotropic molecule that, not only modulates the physicochemical properties and architecture of neuronal plasma membrane, but it is also involved in multiple facets of neuronal biology, from regulation of synaptic function to neuroprotection and modulation of gene expression. As a highly unsaturated fatty acid due to the presence of six double bonds, DHA is susceptible for oxidation, especially in the highly pro-oxidant environment of brain parenchyma. We have recently reported the ability of DHA to regulate the transcriptional program controlling neuronal antioxidant defenses in a hippocampal cell line, especially the glutathione/glutaredoxin system. Within this antioxidant system, DHA was particularly efficient in triggering the upregulation of Gpx4 gene, which encodes for the nuclear, cytosolic and mitochondrial isoforms of phospholipid-hydroperoxide glutathione peroxidase (PH-GPx/GPx4, the main enzyme protecting cell membranes against lipid peroxidation and capable to reduce oxidized phospholipids in situ. We show here that this novel property of DHA is also significant in the hippocampus of wild-type mice and APP/PS1 transgenic mice, a familial model of Alzheimer’s disease. By doing this, DHA stimulates a mechanism to self-protect from oxidative damage even in the neuronal scenario of high aerobic metabolism and in the presence of elevated levels of transition metals, which inevitably favor the generation of reactive oxygen species. Noticeably, DHA also upregulated a novel Gpx4 splicing variant, harboring part of the first intronic region, which according to the ‘sentinel RNA hypothesis’ would expand the ability of Gpx4 (and DHA to provide neuronal antioxidant defense independently of conventional nuclear splicing in cellular compartments, like dendritic zones, located away from nuclear

  12. Nonperturbative Renormalization Group Approach to Polymerized Membranes

    Science.gov (United States)

    Essafi, Karim; Kownacki, Jean-Philippe; Mouhanna, Dominique

    2014-03-01

    Membranes or membrane-like materials play an important role in many fields ranging from biology to physics. These systems form a very rich domain in statistical physics. The interplay between geometry and thermal fluctuations lead to exciting phases such flat, tubular and disordered flat phases. Roughly speaking, membranes can be divided into two group: fluid membranes in which the molecules are free to diffuse and thus no shear modulus. On the other hand, in polymerized membranes the connectivity is fixed which leads to elastic forces. This difference between fluid and polymerized membranes leads to a difference in their critical behaviour. For instance, fluid membranes are always crumpled, whereas polymerized membranes exhibit a phase transition between a crumpled phase and a flat phase. In this talk, I will focus only on polymerized phantom, i.e. non-self-avoiding, membranes. The critical behaviour of both isotropic and anisotropic polymerized membranes are studied using a nonperturbative renormalization group approach (NPRG). This allows for the investigation of the phase transitions and the low temperature flat phase in any internal dimension D and embedding d. Interestingly, graphene behaves just as a polymerized membrane in its flat phase.

  13. Amniotic fluid embolism

    Directory of Open Access Journals (Sweden)

    Kiranpreet Kaur

    2016-01-01

    Full Text Available Amniotic fluid embolism (AFE is one of the catastrophic complications of pregnancy in which amniotic fluid, fetal cells, hair, or other debris enters into the maternal pulmonary circulation, causing cardiovascular collapse. Etiology largely remains unknown, but may occur in healthy women during labour, during cesarean section, after abnormal vaginal delivery, or during the second trimester of pregnancy. It may also occur up to 48 hours post-delivery. It can also occur during abortion, after abdominal trauma, and during amnio-infusion. The pathophysiology of AFE is not completely understood. Possible historical cause is that any breach of the barrier between maternal blood and amniotic fluid forces the entry of amniotic fluid into the systemic circulation and results in a physical obstruction of the pulmonary circulation. The presenting signs and symptoms of AFE involve many organ systems. Clinical signs and symptoms are acute dyspnea, cough, hypotension, cyanosis, fetal bradycardia, encephalopathy, acute pulmonary hypertension, coagulopathy etc. Besides basic investigations lung scan, serum tryptase levels, serum levels of C3 and C4 complements, zinc coproporphyrin, serum sialyl Tn etc are helpful in establishing the diagnosis. Treatment is mainly supportive, but exchange transfusion, extracorporeal membrane oxygenation, and uterine artery embolization have been tried from time to time. The maternal prognosis after amniotic fluid embolism is very poor though infant survival rate is around 70%.

  14. Ca2+-dependent phospholipid scrambling by a reconstituted TMEM16 ion channel.

    Science.gov (United States)

    Malvezzi, Mattia; Chalat, Madhavan; Janjusevic, Radmila; Picollo, Alessandra; Terashima, Hiroyuki; Menon, Anant K; Accardi, Alessio

    2013-01-01

    Phospholipid (PL) scramblases disrupt the lipid asymmetry of the plasma membrane, externalizing phosphatidylserine to trigger blood coagulation and mark apoptotic cells. Recently, members of the TMEM16 family of Ca(2+)-gated channels have been shown to be involved in Ca(2+)-dependent scrambling. It is however controversial whether they are scramblases or channels regulating scrambling. Here we show that purified afTMEM16, from Aspergillus fumigatus, is a dual-function protein: it is a Ca(2+)-gated channel, with characteristics of other TMEM16 homologues, and a Ca(2+)-dependent scramblase, with the expected properties of mammalian PL scramblases. Remarkably, we find that a single Ca(2+) site regulates separate transmembrane pathways for ions and lipids. Two other purified TMEM16-channel homologues do not mediate scrambling, suggesting that the family diverged into channels and channel/scramblases. We propose that the spatial separation of the ion and lipid pathways underlies the evolutionary divergence of the TMEM16 family, and that othe