Membrane Fluidity: The motion of phospholipid molecules within the lipid bilayer, dependent on the classes of phospholipids present, their fatty acid composition and degree of unsaturation of the acyl chains, the cholesterol concentration, and temperature.Membrane Lipids: Lipids, predominantly phospholipids, cholesterol and small amounts of glycolipids found in membranes including cellular and intracellular membranes. These lipids may be arranged in bilayers in the membranes with integral proteins between the layers and peripheral proteins attached to the outside. Membrane lipids are required for active transport, several enzymatic activities and membrane formation.Diphenylhexatriene: A fluorescent compound that emits light only in specific configurations in certain lipid media. It is used as a tool in the study of membrane lipids.Cell Membrane: The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.Fluorescence Polarization: Measurement of the polarization of fluorescent light from solutions or microscopic specimens. It is used to provide information concerning molecular size, shape, and conformation, molecular anisotropy, electronic energy transfer, molecular interaction, including dye and coenzyme binding, and the antigen-antibody reaction.Erythrocyte Membrane: The semi-permeable outer structure of a red blood cell. It is known as a red cell 'ghost' after HEMOLYSIS.Membranes: Thin layers of tissue which cover parts of the body, separate adjacent cavities, or connect adjacent structures.Benzyl Alcohol: A colorless liquid with a sharp burning taste and slight odor. It is used as a local anesthetic and to reduce pain associated with LIDOCAINE injection. Also, it is used in the manufacture of other benzyl compounds, as a pharmaceutic aid, and in perfumery and flavoring.Phospholipids: Lipids containing one or more phosphate groups, particularly those derived from either glycerol (phosphoglycerides see GLYCEROPHOSPHOLIPIDS) or sphingosine (SPHINGOLIPIDS). They are polar lipids that are of great importance for the structure and function of cell membranes and are the most abundant of membrane lipids, although not stored in large amounts in the system.Intracellular Membranes: Thin structures that encapsulate subcellular structures or ORGANELLES in EUKARYOTIC CELLS. They include a variety of membranes associated with the CELL NUCLEUS; the MITOCHONDRIA; the GOLGI APPARATUS; the ENDOPLASMIC RETICULUM; LYSOSOMES; PLASTIDS; and VACUOLES.Membranes, Artificial: Artificially produced membranes, such as semipermeable membranes used in artificial kidney dialysis (RENAL DIALYSIS), monomolecular and bimolecular membranes used as models to simulate biological CELL MEMBRANES. These membranes are also used in the process of GUIDED TISSUE REGENERATION.Liposomes: Artificial, single or multilaminar vesicles (made from lecithins or other lipids) that are used for the delivery of a variety of biological molecules or molecular complexes to cells, for example, drug delivery and gene transfer. They are also used to study membranes and membrane proteins.Membrane Potentials: The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).Laurates: Salts and esters of the 12-carbon saturated monocarboxylic acid--lauric acid.Electron Spin Resonance Spectroscopy: A technique applicable to the wide variety of substances which exhibit paramagnetism because of the magnetic moments of unpaired electrons. The spectra are useful for detection and identification, for determination of electron structure, for study of interactions between molecules, and for measurement of nuclear spins and moments. (From McGraw-Hill Encyclopedia of Science and Technology, 7th edition) Electron nuclear double resonance (ENDOR) spectroscopy is a variant of the technique which can give enhanced resolution. Electron spin resonance analysis can now be used in vivo, including imaging applications such as MAGNETIC RESONANCE IMAGING.Fatty Acids: Organic, monobasic acids derived from hydrocarbons by the equivalent of oxidation of a methyl group to an alcohol, aldehyde, and then acid. Fatty acids are saturated and unsaturated (FATTY ACIDS, UNSATURATED). (Grant & Hackh's Chemical Dictionary, 5th ed)2-Naphthylamine: A naphthalene derivative with carcinogenic action.Cell Membrane Permeability: A quality of cell membranes which permits the passage of solvents and solutes into and out of cells.Temperature: The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.Cholesterol: The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils.Lipid Bilayers: Layers of lipid molecules which are two molecules thick. Bilayer systems are frequently studied as models of biological membranes.Stearates: Salts and esters of the 18-carbon saturated, monocarboxylic acid--stearic acid.Phosphatidylcholines: Derivatives of phosphatidic acids in which the phosphoric acid is bound in ester linkage to a choline moiety. Complete hydrolysis yields 1 mole of glycerol, phosphoric acid and choline and 2 moles of fatty acids.Spin Labels: Molecules which contain an atom or a group of atoms exhibiting an unpaired electron spin that can be detected by electron spin resonance spectroscopy and can be bonded to another molecule. (McGraw-Hill Dictionary of Chemical and Technical Terms, 4th ed)Viscosity: The resistance that a gaseous or liquid system offers to flow when it is subjected to shear stress. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Benzyl Alcohols: Alcohols derived from the aryl radical (C6H5CH2-) and defined by C6H5CHOH. The concept includes derivatives with any substituents on the benzene ring.Fatty Acids, Unsaturated: FATTY ACIDS in which the carbon chain contains one or more double or triple carbon-carbon bonds.Microvilli: Minute projections of cell membranes which greatly increase the surface area of the cell.Erythrocytes: Red blood cells. Mature erythrocytes are non-nucleated, biconcave disks containing HEMOGLOBIN whose function is to transport OXYGEN.Fluorescent Dyes: Agents that emit light after excitation by light. The wave length of the emitted light is usually longer than that of the incident light. Fluorochromes are substances that cause fluorescence in other substances, i.e., dyes used to mark or label other compounds with fluorescent tags.Lipid Peroxidation: Peroxidase catalyzed oxidation of lipids using hydrogen peroxide as an electron acceptor.Alcohols: Alkyl compounds containing a hydroxyl group. They are classified according to relation of the carbon atom: primary alcohols, R-CH2OH; secondary alcohols, R2-CHOH; tertiary alcohols, R3-COH. (From Grant & Hackh's Chemical Dictionary, 5th ed)Basement Membrane: A darkly stained mat-like EXTRACELLULAR MATRIX (ECM) that separates cell layers, such as EPITHELIUM from ENDOTHELIUM or a layer of CONNECTIVE TISSUE. The ECM layer that supports an overlying EPITHELIUM or ENDOTHELIUM is called basal lamina. Basement membrane (BM) can be formed by the fusion of either two adjacent basal laminae or a basal lamina with an adjacent reticular lamina of connective tissue. BM, composed mainly of TYPE IV COLLAGEN; glycoprotein LAMININ; and PROTEOGLYCAN, provides barriers as well as channels between interacting cell layers.Spectrometry, Fluorescence: Measurement of the intensity and quality of fluorescence.Cold Temperature: An absence of warmth or heat or a temperature notably below an accustomed norm.Hexanols: Isomeric forms and derivatives of hexanol (C6H11OH).Lipids: A generic term for fats and lipoids, the alcohol-ether-soluble constituents of protoplasm, which are insoluble in water. They comprise the fats, fatty oils, essential oils, waxes, phospholipids, glycolipids, sulfolipids, aminolipids, chromolipids (lipochromes), and fatty acids. (Grant & Hackh's Chemical Dictionary, 5th ed)Norisoprenoids: Thirteen-carbon butene cyclohexene degradation products formed by the cleavage of CAROTENOIDS. They contribute to the flavor of some FRUIT. Ionone should not be confused with the similarly named ionol.Receptors, Concanavalin A: Glycoprotein moieties on the surfaces of cell membranes that bind concanavalin A selectively; the number and location of the sites depends on the type and condition of the cell.Calcium: A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.Tenuazonic Acid: 3-Acetyl-5-sec-butyl-4-hydroxy-3-pyrrolin-2-one. A metabolite found in a strain of the fungus Alternaria tenuis Auct. which functions as an antibiotic with antiviral and antineoplastic properties, and may also act as a mycotoxin.Ergosterol: A steroid of interest both because its biosynthesis in FUNGI is a target of ANTIFUNGAL AGENTS, notably AZOLES, and because when it is present in SKIN of animals, ULTRAVIOLET RAYS break a bond to result in ERGOCALCIFEROL.Cell Line: Established cell cultures that have the potential to propagate indefinitely.Microscopy, Electron: Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.Hemolysis: The destruction of ERYTHROCYTES by many different causal agents such as antibodies, bacteria, chemicals, temperature, and changes in tonicity.Nisin: A 34-amino acid polypeptide antibiotic produced by Streptococcus lactis. It has been used as a food preservative in canned fruits and vegetables, and cheese.Anisotropy: A physical property showing different values in relation to the direction in or along which the measurement is made. The physical property may be with regard to thermal or electric conductivity or light refraction. In crystallography, it describes crystals whose index of refraction varies with the direction of the incident light. It is also called acolotropy and colotropy. The opposite of anisotropy is isotropy wherein the same values characterize the object when measured along axes in all directions.Pyrenes: A group of condensed ring hydrocarbons.Fatty Acid Desaturases: A family of enzymes that catalyze the stereoselective, regioselective, or chemoselective syn-dehydrogenation reactions. They function by a mechanism that is linked directly to reduction of molecular OXYGEN.Kinetics: The rate dynamics in chemical or physical systems.Diffusion: The tendency of a gas or solute to pass from a point of higher pressure or concentration to a point of lower pressure or concentration and to distribute itself throughout the available space. Diffusion, especially FACILITATED DIFFUSION, is a major mechanism of BIOLOGICAL TRANSPORT.Abetalipoproteinemia: An autosomal recessive disorder of lipid metabolism. It is caused by mutation of the microsomal triglyceride transfer protein that catalyzes the transport of lipids (TRIGLYCERIDES; CHOLESTEROL ESTERS; PHOSPHOLIPIDS) and is required in the secretion of BETA-LIPOPROTEINS (low density lipoproteins or LDL). Features include defective intestinal lipid absorption, very low serum cholesterol level, and near absent LDL.Cells, Cultured: Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.Membrane Transport Proteins: Membrane proteins whose primary function is to facilitate the transport of molecules across a biological membrane. Included in this broad category are proteins involved in active transport (BIOLOGICAL TRANSPORT, ACTIVE), facilitated transport and ION CHANNELS.Hydrogen-Ion Concentration: The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH = log 1/2[1/(H+)], where (H+) is the hydrogen ion concentration in gram equivalents per liter of solution. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Models, Biological: Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.Phosphatidylethanolamines: Derivatives of phosphatidic acids in which the phosphoric acid is bound in ester linkage to an ethanolamine moiety. Complete hydrolysis yields 1 mole of glycerol, phosphoric acid and ethanolamine and 2 moles of fatty acids.Lipid Metabolism: Physiological processes in biosynthesis (anabolism) and degradation (catabolism) of LIPIDS.Mitochondrial Membranes: The two lipoprotein layers in the MITOCHONDRION. The outer membrane encloses the entire mitochondrion and contains channels with TRANSPORT PROTEINS to move molecules and ions in and out of the organelle. The inner membrane folds into cristae and contains many ENZYMES important to cell METABOLISM and energy production (MITOCHONDRIAL ATP SYNTHASE).Escherichia coli: A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.Protein Binding: The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.Membrane Glycoproteins: Glycoproteins found on the membrane or surface of cells.Sodium-Potassium-Exchanging ATPase: An enzyme that catalyzes the active transport system of sodium and potassium ions across the cell wall. Sodium and potassium ions are closely coupled with membrane ATPase which undergoes phosphorylation and dephosphorylation, thereby providing energy for transport of these ions against concentration gradients.Calorimetry, Differential Scanning: Differential thermal analysis in which the sample compartment of the apparatus is a differential calorimeter, allowing an exact measure of the heat of transition independent of the specific heat, thermal conductivity, and other variables of the sample.Microscopy, Fluorescence: Microscopy of specimens stained with fluorescent dye (usually fluorescein isothiocyanate) or of naturally fluorescent materials, which emit light when exposed to ultraviolet or blue light. Immunofluorescence microscopy utilizes antibodies that are labeled with fluorescent dye.Synaptic Membranes: Cell membranes associated with synapses. Both presynaptic and postsynaptic membranes are included along with their integral or tightly associated specializations for the release or reception of transmitters.Sphingomyelins: A class of sphingolipids found largely in the brain and other nervous tissue. They contain phosphocholine or phosphoethanolamine as their polar head group so therefore are the only sphingolipids classified as PHOSPHOLIPIDS.Lysophosphatidylcholines: Derivatives of PHOSPHATIDYLCHOLINES obtained by their partial hydrolysis which removes one of the fatty acid moieties.beta-Cyclodextrins: Cyclic GLUCANS consisting of seven (7) glucopyranose units linked by 1,4-glycosidic bonds.1,2-Dipalmitoylphosphatidylcholine: Synthetic phospholipid used in liposomes and lipid bilayers to study biological membranes. It is also a major constituent of PULMONARY SURFACTANTS.Phosphatidylglycerols: A nitrogen-free class of lipids present in animal and particularly plant tissues and composed of one mole of glycerol and 1 or 2 moles of phosphatidic acid. Members of this group differ from one another in the nature of the fatty acids released on hydrolysis.Rabbits: The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.Permeability: Property of membranes and other structures to permit passage of light, heat, gases, liquids, metabolites, and mineral ions.Mutation: Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.Bacterial Proteins: Proteins found in any species of bacterium.G(M1) Ganglioside: A specific monosialoganglioside that accumulates abnormally within the nervous system due to a deficiency of GM1-b-galactosidase, resulting in GM1 gangliosidosis.1-Butanol: A four carbon linear hydrocarbon that has a hydroxy group at position 1.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Adaptation, Physiological: The non-genetic biological changes of an organism in response to challenges in its ENVIRONMENT.Concanavalin A: A MANNOSE/GLUCOSE binding lectin isolated from the jack bean (Canavalia ensiformis). It is a potent mitogen used to stimulate cell proliferation in lymphocytes, primarily T-lymphocyte, cultures.Ketocholesterols: Cholesterol substituted in any position by a keto moiety. The 7-keto isomer inhibits 3-hydroxy-3-methylglutaryl-CoA reductase activity and inhibits cholesterol uptake in the coronary arteries and aorta in vitro.Ca(2+) Mg(2+)-ATPaseDimyristoylphosphatidylcholine: A synthetic phospholipid used in liposomes and lipid bilayers for the study of biological membranes.Stearic Acids: A group of compounds that are derivatives of octadecanoic acid which is one of the most abundant fatty acids found in animal lipids. (Stedman, 25th ed)Cytochalasin B: A cytotoxic member of the CYTOCHALASINS.Fluorescence: The property of emitting radiation while being irradiated. The radiation emitted is usually of longer wavelength than that incident or absorbed, e.g., a substance can be irradiated with invisible radiation and emit visible light. X-ray fluorescence is used in diagnosis.Oleic Acids: A group of fatty acids that contain 18 carbon atoms and a double bond at the omega 9 carbon.Membrane Microdomains: Detergent-insoluble CELL MEMBRANE components. They are enriched in SPHINGOLIPIDS and CHOLESTEROL and clustered with glycosyl-phosphatidylinositol (GPI)-anchored proteins.Hydrophobic and Hydrophilic Interactions: The thermodynamic interaction between a substance and WATER.Protein Transport: The process of moving proteins from one cellular compartment (including extracellular) to another by various sorting and transport mechanisms such as gated transport, protein translocation, and vesicular transport.Rats, Inbred Strains: Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations or by parent x offspring matings carried out with certain restrictions. This also includes animals with a long history of closed colony breeding.Rats, Wistar: A strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain.Water: A clear, odorless, tasteless liquid that is essential for most animal and plant life and is an excellent solvent for many substances. The chemical formula is hydrogen oxide (H2O). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Semen Preservation: The process by which semen is kept viable outside of the organism from which it was derived (i.e., kept from decay by means of a chemical agent, cooling, or a fluid substitute that mimics the natural state within the organism).Cattle: Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.

Stomatocytosis is absent in "stomatin"-deficient murine red blood cells. (1/1645)

To examine the relationship between erythrocyte membrane protein 7. 2b deficiency and the hemolytic anemia of human hereditary stomatocytosis, we created 7.2b knock-out mice by standard gene targeting approaches. Immunoblots showed that homozygous knock-out mice completely lacked erythrocyte protein 7.2b. Despite the absence of protein 7.2b, there was no hemolytic anemia and mouse red blood cells (RBCs) were normal in morphology, cell indices, hydration status, monovalent cation content, and ability to translocate lipids. The absence of the phenotype of hereditary stomatocytosis implies that protein 7.2b deficiency plays no direct role in the etiology of this disorder and casts doubt on the previously proposed role of this protein as a mediator of cation transport in RBC.  (+info)

Vesicle deformation by an axial load: from elongated shapes to tethered vesicles. (2/1645)

A sufficiently large force acting on a single point of the fluid membrane of a flaccid phospholipid vesicle is known to cause the formation of a narrow bilayer tube (tether). We analyze this phenomenon by means of general mathematical methods allowing us to determine the shapes of strongly deformed vesicles including their stability. Starting from a free vesicle with an axisymmetric, prolate equilibrium shape, we consider an axial load that pulls (or pushes) the poles of the vesicle apart. Arranging the resulting shapes of strained vesicles in dependence of the axial deformation and of the area difference of monolayers, phase diagrams of stable shapes are presented comprising prolate shapes with or without equatorial mirror symmetry. For realistic values of membrane parameters, we study the force-extension relation of strained vesicles, and we demonstrate in detail how the initially elongated shape of an axially stretched vesicle transforms into a shape involving a membrane tether. This tethering transition may be continuous or discontinuous. If the free vesicle is mirror symmetric, the mirror symmetry is broken as the tether forms. The stability analysis of tethered shapes reveals that, for the considered vesicles, the stable shape is always asymmetric (polar), i.e., it involves only a single tether on one side of the main vesicle body. Although a bilayer tube formed from a closed vesicle is not an ideal cylinder, we show that, for most practical purposes, it is safe to assume a cylindrical geometry of tethers. This analysis is supplemented by the documentation of a prototype experiment supporting our theoretical predictions. It shows that the currently accepted model for the description of lipid-bilayer elasticity (generalized bilayer couple model) properly accounts for the tethering phenomenon.  (+info)

Monte Carlo simulation of two-component bilayers: DMPC/DSPC mixtures. (3/1645)

In this paper, we describe a relatively simple lattice model of a two-component, two-state phospholipid bilayer. Application of Monte Carlo methods to this model permits simulation of the observed excess heat capacity versus temperature curves of dimyristoylphosphatidylcholine (DMPC)/distearoylphosphatidylcholine (DSPC) mixtures as well as the lateral distributions of the components and properties related to these distributions. The analysis of the bilayer energy distribution functions reveals that the gel-fluid transition is a continuous transition for DMPC, DSPC, and all DMPC/DSPC mixtures. A comparison of the thermodynamic properties of DMPC/DSPC mixtures with the configurational properties shows that the temperatures characteristics of the configurational properties correlate well with the maxima in the excess heat capacity curves rather than with the onset and completion temperatures of the gel-fluid transition. In the gel-fluid coexistence region, we also found excellent agreement between the threshold temperatures at different system compositions detected in fluorescence recovery after photobleaching experiments and the temperatures at which the percolation probability of the gel clusters is 0.36. At every composition, the calculated mole fraction of gel state molecules at the fluorescence recovery after photobleaching threshold is 0.34 and, at the percolation threshold of gel clusters, it is 0.24. The percolation threshold mole fraction of gel or fluid lipid depends on the packing geometry of the molecules and the interchain interactions. However, it is independent of temperature, system composition, and state of the percolating cluster.  (+info)

Cell membrane dynamics and the induction of apoptosis by lipid compounds. (4/1645)

To investigate the induction of apoptosis by some lipid compounds which are a potent inducer of apoptosis, the plasma membrane fluidity of U937 cells was measured using the fluorescent probe, pyrene. The increase of the membrane fluidity was observed immediately after the treatment of cells with lipid inducers. We also found that the trigger of apoptosis was pulled within 30 min after treatment. Data from the dynamic light scattering experiment indicated that lipid inducers were dissolved to form the emulsion. At the very early stage of apoptosis, possibly, the well-controlled transfer of lipid inducers from the emulsion to the lipid layer of cells can bring about the increase of membrane dynamics which might lead to the induction of apoptosis.  (+info)

The interaction of ubiquinone-3 with phospholipid membranes. (5/1645)

The effects of ubiquinone-3 (UQ) on dipalmitoylphosphatidylcholine (DPPC) membrane were studied by surface monolayer, differential scanning calorimetry (DSC) and fluorescence techniques. DPPC and UQ are proved to be freely miscible in the mixed monolayer at an air/water interface, and to be partially miscible in bulk phase, i.e. bilayer and solid phase. There is a condensing interaction between UQ and DPPC in the UQ/DPPC mixed monolayers. The solubility of UQ in the DPPC is about 20 mole% and the solubility of DPPC in UQ is about 10 mole%. The membrane fluidity of DPPC was increased by the addition of UQ and the phase transition temperature was decreased.  (+info)

Interaction of tumor and normal blood cells with ethylene oxide and propylene oxide block copolymers. (6/1645)

Ethylene oxide and propylene oxide block copolymers (pluronics) are widely known as agents that promote drug penetration across biological barriers. We have studied the interaction of normal and malignant blood cells with pluronics L61 and P85 that have different hydrophobicity. SP2/0 myeloma cells accumulated pluronics while normal cells adsorb most of the polymer on the surface. Interaction of pluronics with cells resulted in drastic changes of membrane microviscosity. Tumor cell membrane microviscosity decreased after pluronics adsorption, in contrast to normal cells, whose membrane microviscosity was enhanced. We suppose that sensitivity of tumor cell membrane microviscosity to the pluronics action correlates with its permeability for molecular substances.  (+info)

The yeast multidrug resistance pump, Pdr5p, confers reduced drug resistance in erg mutants of Saccharomyces cerevisiae. (7/1645)

Mutants of Saccharomyces cerevisiae bearing lesions in the ergosterol biosynthetic pathway exhibit a pleiotropic drug-sensitive phenotype. This has been reported to result from an increased permeability of the membranes of the mutant strains to different drugs. As disruption of the yeast multidrug resistance protein, Pdr5p, results in a similar pleiotropic drug-sensitive phenotype, the possibility that Pdr5p may be functioning with a reduced efficiency in these altered sterol backgrounds was examined. To do this, the function of Pdr5p in isogenic strains of S. cerevisiae that have disruptions in the late stages of the ergosterol biosynthesis pathway (ERG6, ERG2, ERG3, ERG4) was studied. A reduced ability of Pdr5p to confer resistance to different drugs in these strains was observed, which did not appear to be dependent solely on the permeability of the membrane towards the drug. A simultaneous examination was made of how the lipid composition might be altering the efficiency of Pdr5p by similar studies in strains lacking phosphatidylserine synthase (encoded by CHO1). The results indicated that the drug sensitivity of the erg strains is, to a significant extent, a result of the reduced efficiency of the Pdr5p efflux pump, and that the membrane environment plays an important role in determining the drug resistance conferred by Pdr5p.  (+info)

Induction of acetylcholinesterase release from erythrocytes in the presence of liposomes. (8/1645)

When human erythrocytes are incubated with liposomes, the release of acetylcholinesterase (AChE) occurs following an induction period [Cook et al. (1980) Biochemistry 19, 4601-4607]. However, the mechanism of the induction has not been elucidated. We examined the relationships among the lipid transfer from liposomes to erythrocytes, the morphological change of erythrocytes, the fluidity of the erythrocyte membrane and the start of AChE release. The AChE release into the liposomes and into shed-vesicle fractions started simultaneously after an induction period. The morphological index (MI) of erythrocytes was approximately 2.8 at the beginning of the release, regardless of the induction period. AChE was not released from the erythrocytes of index 2.8 even in the presence of liposomes if the MI remained at 2.8. Therefore, for the release, erythrocytes needed a further increase of the MI from 2.8. As the rate of lipid transfer increased, the induction period became shorter. No significant lipid release from erythrocytes was detected during the induction period. The initiation of the AChE release was not simply affected by the change in the membrane fluidity of erythrocytes upon interaction with liposomes. These results first demonstrate that AChE release into the shed-vesicle and liposome fractions is triggered by a further increase of the MI from 2.8, which is induced by lipid transfer from liposomes to erythrocytes.  (+info)

  • Class I sensors interrogate surface properties of cellular membranes, such as the surface charge and molecular packing density as reported for amphipathic lipid-packing sensor (ALPS) motif-containing proteins and other amphipathic helix-containing proteins 31 . (
  • Our results demonstrate that increased membrane fluidity is not the sole cause of growth inhibition and that alcohols may also denature proteins within the membrane and cytosol, adversely affecting metabolism and decreasing cell growth. (
  • As an important step towards a unifying membrane theory, we need to identify a set of membrane properties that are both minimally correlated and sufficient to uniquely describe the state of a bilayer. (
  • Increased membrane fluidity, which causes cofactor leakage and loss of membrane potential, has long been documented as a cause for decreased cell growth during exposure to ethanol, butanol, and other alcohols. (
  • This system enables us to study the flow induced changes in plasma membrane of a representative cancer cell line HeLa as the function of imparted shear stress and importantly, cell-substrate adhesion strength. (
  • We have shown while transient changes in membrane fluidity depend on the orientation of flow and are largely independent of cellsubstrate adhesion landscape, long term membrane fluidization is controlled by the cell-substrate adhesion strength that is represented by maximum traction stress that cell exerts on the microchannel wall. (
  • Tamal Das, Tapas K. Maiti and Suman Chakraborty, "Flow Shear Induced Changes in Membrane Fluidity: Dependence on Cell- Substrate Adhesion Strength", Current Analytical Chemistry (2013) 9: 9. (
  • Membrane lipid analyses and electron spin resonance (ESR) studies of membrane fluidity were carried out on the red cells of a Japanese patient with hereditary high red cell membrane phosphatidylcholine hemolytic anemia (HPCHA). (
  • Cell membrane fluidity to allow toxins to exit the cell for removal by the liver, kidneys, and digestive tract. (
  • By combining molecular dynamics simulations with experiments, we uncover a remarkable sensitivity of the transcriptional regulator Mga2 to the abundance, position, and configuration of double bonds in lipid acyl chains, and provide insights into the molecular rules of membrane adaptation. (
  • Our findings suggest that membrane property sensors have evolved remarkable sensitivities to highly specific aspects of membrane structure and dynamics, thus paving the way toward the development of genetically encoded reporters for such properties in the future. (
  • 372 nm) to excimer (EM 470 nm) fluorescence, a quantitative monitoring of the membrane fluidity can be attained. (
  • How do cells, e.g., balance the need for maintaining membrane fluidity with the need to maintain organelle-specific lateral pressure profiles 20 ? (
  • Characterizing naturally occurring membrane property sensors, which may exhibit highly specialized sensitivities to specific membrane properties, holds promise to better understand how cells prioritize the maintenance of such orthogonal membrane properties 19 . (
  • The overall fluidity of the intact red cells was determined by ESR with a spin probe, 5-SAL. (
  • While the underlying mechanisms behind this have yet to be determined, it may be possible that hypercholesterolemia impairs the fluid shear stress (FSS) inactivation of neutrophils through the rigidifying effect of cholesterol on membrane fluidity. (
  • H.K. Kimelberg, Alterations in phospholipid-dependent (Na+K) ATPase activity due to lipid 'fluidity. (
  • These alterations are reverted when membrane fluidity is restored by a chemical fluidizer. (
  • In the present study, we documented the promising role of thyroid hormones status in animals in modulation of Na + -P i transport activity in intestinal brush border membrane vesicles (BBMV) which was accompanied with alterations in BBM lipid composition and fluidity. (
  • Taurine (TAU) and compounds representing a TAU analog (hypotaurine $=$ HYTAU) or homolog (aminomethanesulfonic acid $=$ AMSA, homotaurine $=$ HMTAU) were tested for their counteracting effects against alterations in erythrocyte (RBC) morphology, membrane fluidity and cytoskeletal spectrin distribution due to diabetes, alcoholism and diabetes-alcoholism in male Goto-Kakizaki rats (made diabetic with a high fat diet and alcoholic upon feeding on a flavored alcohol solution) and Wistar-Kyoto rats (serving as controls). (
  • However, we detected alterations in membrane fluidity and ATPase activity. (
  • In this study we evaluate the alterations in membrane fluidity of blood platelets in patients with various entities of myeloid malignancies. (
  • Melatonin, a well-known antioxidant and neuroimmunomodulator indoleamine, reversed some of these alterations and protected mitochondrial membranes from obvious damage. (
  • Membrane fluidity is a key parameter of bacterial membranes that undergoes quick adaptation in response to environmental challenges and has recently emerged as an important factor in the antibacterial mechanism of membrane-targeting antibiotics. (
  • Bacterial membranes have long been viewed as homogenous lipid bilayers following the classical fluid mosaic membrane model. (
  • The most common simple hopanoid compounds in the bacterial membranes are diplopterol ( Figure 3 ) and diploptene ( Figure 5 ). (
  • Among 40 widely-found elongated hopanoids in the bacterial membranes, the most common hopanoids are aminobacterialhexanetriol and bacteriohopanetetrol . (
  • M. Sinensky, K.P. Minneman and P.B. Molinoff, Increased membrane acyl chain ordering activates adenylate cyclase, J. Biol. (
  • Role of serum 1,25-dihydroxyvitamin D3 levels and intestinal brush border membrane fluidity. (
  • In a group of subjects with vascular atherosclerotic disease (VAD) and in a group of normal controls we evaluated, at baseline and after in vitro chemotactic activation (prolonged for 5 and 15 min) with two stimulating agents (PMA and fMLP), the polymorphonuclear (PMN) filtration parameters, PMN me mbrane fluidity and PMN cytosolic Ca2+ content. (
  • Lipid packing can influence the fluidity of the membrane. (
  • In order to study if the surface modification of SPIONs has any influence on these membrane properties, we have used four types of differently functionalized SPIONs, such as: plain SPIONs (primary size was shown to be ~11 nm), silica-coated SPIONs, SPIONs coated with silica and functionalized with positively charged amino groups or negatively charged carboxyl groups (the primary size of all the surface-modified SPIONs was ~20 nm). (
  • Lower dose of Kh on day 1 after treatment induced higher mitochondrial membrane fluidity than control group. (
  • We observed changes in mitochondrial membrane lipids, and fatty acids, following intracerebral injection of fibrillar A β in aged Wistar rats. (
Regulation of lipid saturation without sensing membrane fluidity | Nature Communications
Regulation of lipid saturation without sensing membrane fluidity | Nature Communications (
Role of Alcohols in Growth, Lipid Composition, and Membrane Fluidity of Yeasts, Bacteria, and Archaea | Applied and...
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Flow Shear Induced Changes in Membrane Fluidity: Dependence on Cell- Substrate Adhesion Strength | Bentham Science
Flow Shear Induced Changes in Membrane Fluidity: Dependence on Cell- Substrate Adhesion Strength | Bentham Science (
Membrane Fluidity and Cellular Functions | SpringerLink
Membrane Fluidity and Cellular Functions | SpringerLink (
Cell - Membrane lipids | Britannica
Cell - Membrane lipids | Britannica (
Membrane fluidity - Biology Forum | Biology-Online Dictionary, Blog & Forum
Membrane fluidity - Biology Forum | Biology-Online Dictionary, Blog & Forum (
Rinse Boer, de - Research database - University of Groningen
Rinse Boer, de - Research database - University of Groningen (
Mycobacterium tuberculosis review - microbewiki
Mycobacterium tuberculosis review - microbewiki (
Cytosine Arabinoside Transport & Membrane Fluidity in Acute Leukaemia  | Cancer Council Victoria
Cytosine Arabinoside Transport & Membrane Fluidity in Acute Leukaemia | Cancer Council Victoria (
Fluidity | physics | Britannica
Fluidity | physics | Britannica (
Hopanoid lipid - microbewiki
Hopanoid lipid - microbewiki (
European Industrial Pharmacy Issue 14 (September 2012) by European Industrial Pharmacists Group (EIPG) - issuu
European Industrial Pharmacy Issue 14 (September 2012) by European Industrial Pharmacists Group (EIPG) - issuu (
February 1999 - Volume 17 - Issue 2 : Journal of Hypertension
February 1999 - Volume 17 - Issue 2 : Journal of Hypertension (
Articles by Kazushi Tsuda : Journal of Hypertension
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Toxins  | Free Full-Text | Evaluation of the Liver Toxicity of Pterocephalus hookeri Extract via Triggering Necrosis | HTML
Toxins | Free Full-Text | Evaluation of the Liver Toxicity of Pterocephalus hookeri Extract via Triggering Necrosis | HTML (
Volume 78, Issue 4
JCI - Volume 78, Issue 4 (
Membrane Fluidity and Membrane Activities | SpringerLink
Membrane Fluidity and Membrane Activities | SpringerLink (
Suppression of monosodium urate crystal-induced inflammation by black currant seed oil | SpringerLink
Suppression of monosodium urate crystal-induced inflammation by black currant seed oil | SpringerLink (
Lymphocyte Activation and Membrane Fluidity in IGA Nephropathy | Clinical Science
Lymphocyte Activation and Membrane Fluidity in IGA Nephropathy | Clinical Science (
Clinical Hemorheology and Microcirculation - Volume 12, issue 3 - Journals - IOS Press
Clinical Hemorheology and Microcirculation - Volume 12, issue 3 - Journals - IOS Press (
Techniques in Cell Cycle Analysis by Joe W. Gray,  Zbigniew Darzynkiewicz |, Paperback | Barnes & Noble®
Techniques in Cell Cycle Analysis by Joe W. Gray, Zbigniew Darzynkiewicz |, Paperback | Barnes & Noble® (
Intermolecular Hydrogen Bonding between Membrane Lipids | SpringerLink
Intermolecular Hydrogen Bonding between Membrane Lipids | SpringerLink (
Membrane Fluidity Is Regulated Cell Non-autonomously by Caenorhabditis elegans PAQR-2 and Its Mammalian Homolog AdipoR2 |...
Membrane Fluidity Is Regulated Cell Non-autonomously by Caenorhabditis elegans PAQR-2 and Its Mammalian Homolog AdipoR2 |... (
Arachidonic acid - Wikipedia
Arachidonic acid - Wikipedia (
My Sulfite Headache - Skepchick
My Sulfite Headache - Skepchick (
Sweet basil (Ocimum basilicum) | Plant Profiler | Sigma-Aldrich
Sweet basil (Ocimum basilicum) | Plant Profiler | Sigma-Aldrich (
Response Mechanisms of Bacterial Degraders to Environmental Contaminants on the Level of Cell Walls and Cytoplasmic Membrane
Response Mechanisms of Bacterial Degraders to Environmental Contaminants on the Level of Cell Walls and Cytoplasmic Membrane (
Frontiers | ALA6, a P4-type ATPase, Is Involved in Heat Stress Responses in Arabidopsis thaliana | Plant Science
Frontiers | ALA6, a P4-type ATPase, Is Involved in Heat Stress Responses in Arabidopsis thaliana | Plant Science (
Search Results -   - 28 Results - Digital Library
Search Results - - 28 Results - Digital Library (
Frontiers | Loss of Function of Fatty Acid Desaturase 7 in Tomato Enhances Photosynthetic Carbon Fixation Efficiency | Plant...
Frontiers | Loss of Function of Fatty Acid Desaturase 7 in Tomato Enhances Photosynthetic Carbon Fixation Efficiency | Plant... (
Free Physiology Flashcards about Phys3 Thermoregulate
Free Physiology Flashcards about Phys3 Thermoregulate (
SEURAT-1 liver gold reference compounds: a mechanism-based review | SpringerLink
SEURAT-1 liver gold reference compounds: a mechanism-based review | SpringerLink (