Search results for "fluidit"
showing 10 items of 239 documents
Membrane fluidity and the surface properties of the lipid bilayer: ESR experiment and computer simulation
2009
Penetration of the liposome membranes formed in the gel phase from DPPC (DPPC liposomes) and in the liquid-crystalline phase from egg yolk lecithin (EYL liposomes) by the TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) and 16 DOXYL (2-ethyl-2-(15-methoxy-oxopentadecyl)-4,4-dimethyl-3-oxazolidinyloxy) spin probes has been investigated. The penetration process was followed by 120 hours at 24(0)C, using the electron spin resonance (ESR) method. The investigation of the kinetics of the TEMPO probe building into the membranes of both types of liposomes revealed differences appearing 30 minutes after the start of the experiment. The number of TEMPO particles built into the EYL liposome membranes beg…
Mechanisms underlying the toxicity of lactone aroma compounds towards the producing yeast cells
2003
M. A G U E D O , L. B E N E Y , Y. W A C H EA N D J. - M. B E L I N. 2003. Aims: To study the fundamental mechanisms of toxicity of the fruity aroma compound c-decalactone, that lead to alterations in cell viability during its biotechnological production by yeast cells; Yarrowia lipolytica that is able to produce high amounts of this metabolite was used here as a model. Methods and Results: Lactone concentrations above 150 mg l )1 inhibited cell growth, depolarized the living cells and increased membrane fluidity. Infrared spectroscopic measurements revealed that the introduction of the lactone into model phospholipid bilayers, decreased the phase transition temperature. Moreover, the H + -…
Effects of oxidoreduction potential combined with acetic acid, NaCl and temperature on the growth, acidification, and membrane properties of Lactobac…
2002
International audience; The effects of oxidoreduction potential (Eh) combined with acetic acid, NaCl and temperature on the growth, acidification, and membrane properties of Lactobacillus plantarum were studied. The culture medium was set at pH 5, and two different Eh values were adjusted using nitrogen (Eh = +350 mV) or hydrogen (Eh = -300 mV) gas. In reducing condition, the growth was slowed and the acidification delayed at 37 degrees C, but not at 10 degrees C. A synergistic inhibitory effect of reducing Eh, acetic acid and NaCl was observed, mainly for delaying the lag phase before acidification. These results may be explained by changes in ATPase activity, membrane fluidity and surface…
Scrutiny of the Failure of Lipid Membranes As A Function of Headgroups, Chain Length, and Lamellarity Measured by Scanning Force Microscopy
2004
AbstractA fast, quantitative, and unambiguous screening of material properties of biomembranes using scanning force microscopy in pulsed force mode on lipid membranes is presented. The spatially resolved study of breakthrough force, breakthrough distance, adhesion, stiffness, and topography of lipid membranes as determined simultaneously by digitalized pulsed force mode provides new insight into the structure-function relationship of model membranes, which are systematically analyzed by varying chain length, lipid headgroup, and lamellarity. For this purpose, a novel unbiased analysis method is presented. A strong correlation between adhesion and breakthrough events is found on lipid bilaye…
Partitioning of Pyrene-Labeled Phospho- and Sphingolipids between Ordered and Disordered Bilayer Domains
2004
AbstractHere we have studied how the length of the pyrene-labeled acyl chain (n) of a phosphatidylcholine, sphingomyelin, or galactosylceramide affects the partitioning of these lipids between 1), gel and fluid domains coexisting in bovine brain sphingomyelin (BB-SM) or BB-SM/spin-labeled phosphatidylcholine (PC) bilayers or 2), between liquid-disordered and liquid-ordered domains in BB-SM/spin-labeled PC/cholesterol bilayers. The partitioning behavior was deduced either from modeling of pyrene excimer/monomer ratio versus temperature plots, or from quenching of the pyrene monomer fluorescence by spin-labeled PC. New methods were developed to model excimer formation and pyrene lipid quenchi…
Effect of the extract of Ginkgo biloba (EGb 761) on the circulating and cellular profiles of polyunsaturated fatty acids: correlation with the anti-o…
2000
Abstract Ginkgo biloba extract (EGb 761) has beneficial effects on cognitive functions in aging patients, and on various pathologies, including cardiovascular diseases. Although the extract is known to have antioxidant properties and improve membrane fluidity, the cellular mechanisms underlying these effects have not been determined. Here, we examined the in vivo effects of EGb 761 on circulating and cellular lipids. EGb 761 treatment induced significant increases in the levels of circulating polyunsaturated fatty acids (PUFAs), and a decrease in the saturation index SI (saturated/polyunsaturated species). Plasma triglycerides and cholesterol were not affected, while phospholipids were slig…
Membrane fluidity and fatty acid metabolism in kidney cells from rats fed purified eicosapentaenoic acid or purified docosahexaenoic acid
1998
Hagve T-A, Woldseth B, Brox J, Narce M, Poisson J-P. Membrane £uidity and fatty acid metabolism in kidney cells from rats fed puri¢ed eicosapentaenoic acid or puri¢ed docosahexaenoic acid. Scand J Clin Lab Invest 1998; 58: 187^194. Rats were given a supplement (1.5 ml/day) of purified eicosapentaenoic acid (EPA, 20:5,n-3), purified docosahexaenoic acid (DHA, 22:6,n-3)), or corn oil for 10 days. Membrane fluidity, measured as the steady-state fluorescence polarization of diphenylhexatriene (DPH), was approximately 20% lower in kidney cells from rats fed purified EPA than in cells from the DHA-fed or corn-oil fed animals. The level of 20:5(n-3) in kidney phospholipids was 18 times higher in r…
Leukocyte flow properties, polymorphonuclear membrane fluidity, and cytosolic Ca2+ content in subjects with vascular atherosclerotic disease with and…
1996
The aim of this research was the evaluation of white blood cell (WBC) filtration, reflecting WBC flow properties, polymorphonuclear cell membrane fluidity, and cytosolic Ca 2+ content in subjects with vascular atherosclerotic disease (VAD) and in VAD subjects with noninsulin-dependent diabetes mellitus (NIDDM), in good hemodynamic balance. The authors examined WBC filtration (unfractionated, mononuclear [MN], polymorphonu clear [PMN] cells), using the St. George Filtrometer and considering, respectively, the initial relative flow rate (IRFR) and the clogging rate (CR); the PMN membrane fluidity, employing the fluorescent probe TMA-DPH and calculating the fluorescence polarization degree; a…
Acute Ischemic Stroke
2000
Background and Purpose —Several reports have considered the role of systemic leukocytes in acute ischemic stroke (AIS). Initially, greater attention was focused on the leukocyte count and subsequently on their adhesiveness, aggregation, rheology, and activation. The aim of this study was the evaluation of certain polymorphonuclear leukocyte (PMN) parameters, reflecting their rheology and activation, in subjects with AIS. Methods —In a group of 19 subjects with AIS and in a control group of 18 subjects with asymptomatic vascular atherosclerotic disease, we evaluated the PMN membrane fluidity and cytosolic Ca 2+ concentration at baseline and after in vitro chemotactic activation with 4-phorb…
Chronic renal failure: leukocyte rheology and polymorphonuclear cytosolic Ca2+ concentration.
2000
In a group of subjects with chronic renal failure (CRF), we evaluated the leukocyte rheological activity, expressed as the filtration rate, the polymorphonuclear (PMN) membrane fluidity and the PMN cytosolic Ca2+ content. Using the St. George's Filtrometer, we determined the filtration rate of unfractionated, mononuclear and PMN leukocytes. Using the fluorescent probe 1.4-(trimethylamino)-phenyl-4-phenyl-hexatriene (TMA-DPH), we examined the PMN membrane fluidity and, using the Fura 2-AM, the PMN cytosolic Ca2+ content. From the results obtained, it is evident that only the initial relative flow rate of unfractionated leukocytes was significantly reduced in subjects with CRF, while the filt…