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1

Oleamide-mediated sleep induction does not depend on perturbation of membrane homeoviscosity  

Microsoft Academic Search

To verify whether the sleep-inducing properties of oleamide were related to its ability to perturb membrane homeoviscosity, affecting 5-HT2A receptors, we compared the effects of oleamide and oleic acid, the latter lacking both the sleep-inducing effect and the action on 5-HT2A receptors. In binding studies the two compounds did not directly interact with rat brain cortex 5-HT2A receptors, nor did

Marco Gobbi; Tiziana Mennini; Fabio Dalla Valle; Luigi Cervo; Mario Salmona; Luisa Diomede

1999-01-01

2

In Vivo Evidence that N-Oleoylglycine Acts Independently of Its Conversion to Oleamide  

PubMed Central

Oleamide (cis-9-octadecenamide) is a member of an emerging class of lipid-signaling molecules, the primary fatty acid amides. A growing body of evidence indicates that oleamide mediates fundamental neurochemical processes including sleep, thermoregulation, and nociception. Nevertheless, the mechanism for oleamide biosynthesis remains unknown. The leading hypothesis holds that oleamide is synthesized from oleoylglycine via the actions of the peptide amidating enzyme, peptidylglycine alpha amidating monooxygenase (PAM). The present study investigated this hypothesis using pharmacologic treatments, physiologic assessments, and measurements of serum oleamide levels using a newly development enzyme-linked immunosorbant assay (ELISA). Oleamide and oleoylglycine both induced profound hypothermia and decreased locomotion, over equivalent dose ranges and time courses, whereas, closely related compounds, stearamide and oleic acid, were essentially without effect. While the biologic actions of oleamide and oleoylglycine were equivalent, the two compounds differed dramatically with respect to their effects on serum levels of oleamide. Oleamide administration (80 mg/kg) elevated blood-borne oleamide by eight-fold, whereas, the same dose of oleoylglycine had no effect on circulating oleamide levels. In addition, pretreatment with the established PAM inhibitor, disulfiram, produced modest reductions in the hypothermic responses to both oleoylglycine and oleamide, suggesting that the effects of disulfiram were not mediated through inhibition of PAM and a resulting decrease in the formation of oleamide from oleoylglycine. Collectively, these findings raise the possibilities that: (1) oleoylglycine possesses biologic activity that is independent of its conversion to oleamide, and (2) the increased availability of oleoylglycine as a potential substrate does not drive the biosynthesis of oleamide. PMID:17085322

Chaturvedi, Shalini; Driscoll, William J.; Elliot, Brenda M.; Faraday, Martha M.; Grunberg, Neil E.; Mueller, Gregory P.

2006-01-01

3

Neuropharmacological effects of oleamide in male and female mice.  

PubMed

Oleamide, a fatty acid amide accumulates selectively in the cerebrospinal fluid of sleep deprived cats and rats. Oleamide has been reported to have effects on a wide range of receptors and neurotransmitter systems especially the centrally acting ones for example, dopamine acetylcholine, serotonin, gamma aminobutyric acid (GABA), cannabinoid and vanilloid among others. This suggests a wide range of central nervous system effects of the compound. The effects of intraperitoneal administered oleamide on Novelty-induced behaviours, learning and memory and forced swimming-induced depression were studied. The relative effects of the compound on the male and female mice were also noted. Oleamide dose-dependently reduced (p<0.05) novelty induced rearing, grooming and locomotion. The effects on the all NIBs started within the first 10 min of the test and the peak of the effects was observed during the third 10 min period of the test. Effect of oleamide on short-term working memory was significantly (p<0.05) affected only with the dose of 5mg/kg while the other dose of 10mg/kg had no effect. In the forced swimming test, acute triple intraperitoneal administration of oleamide at 10mg/kg induced a significant reduction in the immobility duration in mice signifying an antidepressant effect. Sex differences in the effects of oleamide (10mg/kg, i.p.) were clearly evident in active behaviours in FST. These results confirm the multiplicity of central nervous system receptors and neurotransmitters that oleamide interacts with hence its numerous and diverse neuropharmacological effects. Most importantly, the present study suggests that oleamide has antidepressant-like property. PMID:17588682

Akanmu, Moses A; Adeosun, Samuel O; Ilesanmi, Olapade R

2007-08-22

4

Enhanced radiosensitization of p53 mutant cells by oleamide  

SciTech Connect

Purpose: Effect of oleamide, an endogenous fatty-acid primary amide, on tumor cells exposed to ionizing radiation (IR) has never before been explored. Methods and Materials: NCI H460, human lung cancer cells, and human astrocytoma cell lines, U87 and U251, were used. The cytotoxicity of oleamide alone or in combination with IR was determined by clonogenic survival assay, and induction of apoptosis was estimated by FACS analysis. Protein expressions were confirmed by Western blotting, and immunofluorescence analysis of Bax by use of confocal microscopy was also performed. The combined effect of IR and oleamide to suppress tumor growth was studied by use of xenografts in the thighs of nude mice. Results: Oleamide in combination with IR had a synergistic effect that decreased clonogenic survival of lung-carcinoma cell lines and also sensitized xenografts in nude mice. Enhanced induction of apoptosis of the cells by the combined treatment was mediated by loss of mitochondrial membrane potential, which resulted in the activation of caspase-8, caspase-9, and caspase-3 accompanied by cytochrome c release and Bid cleavage. The synergistic effects of the combined treatment were more enhanced in p53 mutant cells than in p53 wild-type cells. In p53 wild-type cells, both oleamide and radiation induced Bax translocation to mitochondria. On the other hand, in p53 mutant cells, radiation alone slightly induced Bax translocation to mitochondria, whereas oleamide induced a larger translocation. Conclusions: Oleamide may exhibit synergistic radiosensitization in p53 mutant cells through p53-independent Bax translocation to mitochondria.

Lee, Yoon-Jin [Laboratory of Radiation Effect, Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of); Chung, Da Yeon [Laboratory of Radiation Effect, Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of); Lee, Su-Jae [Laboratory of Experimental Radiation Therapeutics, Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of); Ja Jhon, Gil [Laboratory of Radiation Effect, Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of); Laboratory of Experimental Radiation Therapeutics, Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of); Division of Molecular Life Science, Ewha Woman's University, Seoul (Korea, Republic of); Lee, Yun-Sil [Laboratory of Radiation Effect, Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of)]. E-mail: yslee@kcch.re.kr

2006-04-01

5

Interaction of delta sleep-inducing peptide and its analogues with cellular membranes: A structure-function analysis  

Microsoft Academic Search

The possibility of a correlation between the membrane properties of the delta sleep-inducing peptide (DSIP) and its analogues\\u000a and their biological activity in vivo was examined by a comparative study of the membrane effects of these peptides. The peptides\\u000a exhibiting biological activity in vivo were shown to cause a statistically reliable disordering of lipids in thrombocyte plasma\\u000a membranes similar to

I. I. Mikhaleva; G. T. Rikhireva; I. A. Prudchenko; I. N. Golubev

2006-01-01

6

Pharmacodynamic effects of the sleep inducer zopiclone.  

PubMed

Pharmacodynamic effects of [6-(5-chloro-2-pyridyl)-6,7-dihydro-7-oxo-5H-pyrrolo[3,4-b]pyrazin -5- yl]-4-methyl-1-piperazine-carboxylate (zopiclone, RP-27267), chemically unrelated to benzodiazepines and a potential new sleep inducer, on the peripheral system were investigated in several species of animals. The drug was dissolved in the vehicle of 0.01 mol/l HCl solution for intravenous administration or for addition to the bath medium and was suspended in 0.25% carboxymethylcellulose solution for oral administration. In unanesthetized rabbits, zopiclone, 0.5 mg/kg i.v., exerted no action and at 1 mg/kg slightly decreased respiration and heart rate without affecting blood pressure and ECG. Zopiclone at 10(-6) g/ml had no action in the isolated guinea-pig atria but at 10(-5) g/ml it produced a gradual and slight decrease in heart rate without affecting the contraction. In the isolated small intestine of rabbits and guinea-pigs, zopiclone at 10(-6) g/ml had no action but produced a slight inhibition in a dose of 10(-5) g/ml. Zopiclone, 10(-5) g/ml, did not affect the stimulatory effects of acetylcholine, serotonin, histamine and barium in the isolated guinea-pig intestine. Zopiclone, 1, 5 and 10 mg/kg i.v., exerted no action on rabbit intestinal movement in vivo. Zopiclone, 5, 10, 20 and 50 mg/kg p.o., had no effect on the propulsive motility of the mouse intestine. Zopiclone, 10(-5) g/ml, did not affect contractile movement of the uterus isolated from rabbits and did not influence the contractile response to epinephrine.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3449060

Tokunaga, T; Morishita, H; Kushiku, K; Abe, M; Matsuki, J; Inoue, T; Kawamoto, H; Furukawa, T

1987-12-01

7

Stereoselective modulatory actions of oleamide on GABAA receptors and voltage-gated Na+ channels in vitro: a putative endogenous ligand for depressant drug sites in CNS  

PubMed Central

cis-9,10-octadecenoamide (‘oleamide') accumulates in CSF on sleep deprivation. It induces sleep in animals (the trans form is inactive) but its cellular actions are poorly characterized. We have used electrophysiology in cultures from embryonic rat cortex and biochemical studies in mouse nerve preparations to address these issues. Twenty ?M cis-oleamide (but not trans) reversibly enhanced GABAA currents and depressed the frequency of spontaneous excitatory and inhibitory synaptic activity in cultured networks. cis-oleamide stereoselectively blocked veratridine-induced (but not K+-induced) depolarisation of mouse synaptoneurosomes (IC50, 13.9??M). The cis isomer stereoselectively blocked veratridine-induced (but not K+-induced) [3H]-GABA release from mouse synaptosomes (IC50, 4.6??M). At 20??M cis-oleamide, but not trans, produced a marked inhibition of Na+ channel-dependent rises in intrasynaptosomal Ca2+. The physiological significance of these observations was examined by isolating Na+ spikes in cultured pyramidal neurones. Sixty-four ?M cis-oleamide did not significantly alter the amplitude, rate of rise or duration of unitary action potentials (1?Hz). cis-Oleamide stereoselectively suppressed sustained repetitive firing (SRF) in these cells with an EC50 of 4.1??M suggesting a frequency- or state-dependent block of voltage-gated Na+ channels. Oleamide is a stereoselective modulator of both postsynaptic GABAA receptors and presynaptic or somatic voltage-gated Na+ channels which are crucial for synaptic inhibition and conduction. The modulatory actions are strikingly similar to those displayed by sedative or anticonvulsant barbiturates and a variety of general anaesthetics. Oleamide may represent an endogenous modulator for drug receptors and an important regulator of arousal. PMID:10694234

Verdon, Bernard; Zheng, Jian; Nicholson, Russell A; Ganelli, C Robin; Lees, George

2000-01-01

8

Effect of delta sleep-inducing peptide on macromolecule biosynthesis in brain tissue of stressed rodents  

Microsoft Academic Search

For evaluation of the nature of adaptogenic properties of delta sleep-inducing peptide we studied the effect of this substance\\u000a on macromolecule biosynthesis in the brain of rats and mice exposed to burn injury and psychoemotional stress, respectively.\\u000a Anabolic activity of delta sleep-inducing peptide depended on the purpose of adaptation corresponding to the type of stress.

M. G. Makletsova; I. I. Mikhaleva; I. A. Prudchenko; G. T. Rikhireva

2006-01-01

9

Delta sleep-inducing peptide (DSIP): a still unresolved riddle.  

PubMed

Delta sleep-inducing peptide (DSIP) was isolated from rabbit cerebral venous blood by Schoenenberger-Monnier group from Basel in 1977 and initially regarded as a candidate sleep-promoting factor. However, the link between DSIP and sleep has never been further characterized, in part because of the lack of isolation of the DSIP gene, protein and possible related receptor. Thus the hypothesis regarding DSIP as a sleep factor is extremely poorly documented and still weak. Although DSIP itself presented a focus of study for a number of researchers, its natural occurrence and biological activity still remains obscure. DSIP structure is different from any other known representative of the various peptide families. In this mini-review we hypothesize the existence of a DSIP-like peptide(s) that is responsible (at least partly) for DSIP-like immunoreactivity and DSIP biological activity. This assumption is based on: (i) a highly specific distribution of DSIP-like immunoreactivity in the neurosecretory hypothalamic nuclei of various vertebrate species that are not particularly relevant for sleep regulation, as revealed by the histochemical studies of the Geneva group (Charnay et al.); (ii) a large spectrum of DSIP biological activity revealed by biochemical and physiological studies in vitro; (iii) significant slow-wave sleep (SWS) promoting activity of certain artificial DSIP structural analogues (but not DSIP itself!) in rabbits and rats revealed by our early studies; and (iv) significant SWS-promoting activity of a naturally occurring dermorphin-decapeptide that is structurally similar to DSIP (in five of the nine positions) and the sleep-suppressing effect of its optical isomer, as revealed in rabbits. Potential future studies are outlined, including natural synthesis and release of this DSIP-like peptide and its role in neuroendocrine regulation. PMID:16539679

Kovalzon, Vladimir M; Strekalova, Tatyana V

2006-04-01

10

Identification of oleamide in Guatteria recurvisepala by LC/MS-based Plasmodium falciparum thioredoxin reductase ligand binding method.  

PubMed

Our current research on applications of mass spectrometry to natural product drug discovery against malaria aims to screen plant extracts for new ligands to Plasmodium falciparum thioredoxin reductase (PfTrxR) followed by their identification and structure elucidation. PfTrxR is involved in the antioxidant defense and redox regulation of the parasite and is validated as a promising target for therapeutic intervention against malaria. In the present study, detannified methanol extracts from Guatteria recurvisepala, Licania kallunkiae, and Topobea watsonii were screened for ligands to PfTrxR using ultrafiltration and liquid chromatography/mass spectrometry-based binding experiments. The PfTrxR ligand identified in the extract of Guatteria recurvisepala displayed a relative binding affinity of 3.5-fold when incubated with 1 ?M PfTrxR. The ligand corresponding to the protonated molecule m/z 282.2792 [M+ H]+ was eluted at a retention time of 17.95 min in a 20-min gradient of 95% B consisting of (A) 0.1%formic acid in 95% H?O-5% ACN, and (B) 0.1% formic acid in 95% ACN-5% H?O in an LC-QTOF-MS.Tandem MS of the protonated molecule m/z 282.2792 [M + H]+, C??H??NO (DBE: 2; error: 1.13 ppm) resulted in two daughter ions m/z 265.2516[M + H-NH?]+ (DBE: 3; error: 0.35 ppm) and m/z 247.2405 [M + H-NH?-H?O] +, (DBE: 4; error:2.26 ppm). The PfTrxR ligand was identified as oleamide and confirmed by comparison of the retention time, molecular formula, accurate mass,and double bond equivalence with the standard oleamide. This is the first report on the identification of oleamide as a PfTrxR ligand from Guatteria recurvisepala R. E. Fr. and the corresponding in vitro activity against P. falciparum strain K1 (IC?? 4.29 ?g/mL). PMID:21567357

Munigunti, Ranjith; Nelson, Nicholas; Mulabagal, Vanisree; Gupta, Mahabir P; Brun, Reto; Calderón, Angela I

2011-10-01

11

Nasal Continuous Positive Airway Pressure Reduces Sleep-induced Blood Pressure Increments In Preeclampsia  

Microsoft Academic Search

Preeclampsia is the predominant cause of admissions to neonatal intensive care. The diurnal blood pressure pattern is flattened or reversed in preeclampsia. We hypothesized that snoring and par- tial upper airway obstruction contribute to nocturnal rises in blood pressure. We tested this hypothesis by controlling sleep- induced upper airway flow limitation and snoring with nasal posi- tive pressure. Eleven women

N. EDWARDS; D. M. BLYTON; T. KIRJAVAINEN; G. J. KESBY; C. E. SULLIVAN

12

Lipids  

NSDL National Science Digital Library

Paul Anderson describes the lipids (of the fats). He explains how they are an important source of energy but are also required to cell membranes. He explains how the hydrocarbon tails in triglycerides contain energy available for life. He also explains how phospholipids construct, and cholesterol molecules main the cell membrane.

Anderson, Paul

2013-03-12

13

Delta sleep-inducing peptide and its tetrapeptide analogue alleviate severity of metaphit seizures  

Microsoft Academic Search

The effects of delta sleep-inducing peptide (DSIP) and its tetrapeptide analogue, DSIP(1-4), on metaphit-induced audiogenic seizures were studied. Five groups of adult male Wistar rats were intraperitoneally treated with (1) saline, (2) metaphit, (3) DSIP, (4) metaphit+DSIP and (5) metaphit+DSIP(1-4). To examine blocking effects of DSIP and its analogue on fully developed metaphit seizures, the last two groups were injected

Olivera Stanojlovi?; Dragana Živanovi?; Slobodan Mirkovi?; Inessa Mikhaleva

2004-01-01

14

Mechanism of biological effect of the delta-sleep-inducing peptide includes activation of deoxyribonucleotide synthesis  

Microsoft Academic Search

To find out the mechanism of oncoprotective effects of the delta-sleep-inducing peptide, we have studied the dynamics of ribonucleotide\\u000a reductase activity, which is a vital enzyme in the DNA biosynthesis, using electron paramagnetic resonance (EPR), and a concentration\\u000a of low molecular mass iron complexes in the murine spleen after intraperitoneal injection of the peptide and the antitumor\\u000a preparation methylnitrosourea. The

G. T. Rikhireva; M. K. Pulatova; V. L. Sharigin; M. G. Makletsova; I. I. Mikhaleva

2009-01-01

15

Zolpidem and triazolam do not affect the nocturnal sleep-induced memory improvement  

Microsoft Academic Search

Rationale  It is widely accepted that sleep facilitates memory consolidation. Hypnotics (e.g., benzodiazepines), which reportedly increase\\u000a sleep efficiency but also modify sleep architecture, could affect memory improvement that occurs during sleep.\\u000a \\u000a \\u000a \\u000a Objectives  The present study examined the effects of single doses of two short half-life hypnotics, zolpidem and triazolam, on sleep-induced\\u000a improvement of memory.\\u000a \\u000a \\u000a \\u000a Methods  Twenty-two healthy volunteers participated in this randomized, double-blind,

Jaime Meléndez; Irina Galli; Katica Boric; Alonso Ortega; Leonardo Zuñiga; Carlos F. Henríquez-Roldán; Ana M. Cárdenas

2005-01-01

16

Interaction of Delta Sleep-inducing Peptide and Valproate on Metaphit Audiogenic Seizure Model in Rats  

Microsoft Academic Search

Effects of valproate (VPA), a conventional antiepileptic drug and natural delta sleep-inducing peptide (DSIP) on metaphit\\u000a (1-[1-(3-isothiocyanatophenyl)-cyclohexyl]-piperidine)-induced audiogenic reflex epilepsy were studied. For the purpose of the study, valproate in the doses of 50 or 75 mg\\/kg and\\u000a DSIP (1.0 mg\\/kg) was i.p. injected either alone or in combination to adult Wistar male rats with fully developed metaphit\\u000a seizures after eight audiogenic

Olivera Stanojlovi?; Dragan Hrn?i?; Aleksandra Raši?; Helena Lon?ar-Stevanovi?; Dragan Djuric; Veselinka Šuši?

2007-01-01

17

Effects of Delta-Sleep-Inducing Peptide on 24Hour Sleep-Wake Behaviour in Severe Chronic Insomnia  

Microsoft Academic Search

Impaired daytime functions are a significant part of chronic insomnia besides sleep disturbance. Therefore, the effects of intermediate-term delta-sleep-inducing peptide (DSIP) administration on sleep and daytime performance were investigated in 14 middle-aged chronic insomniacs. DSIP was administered under placebo-controlled, double-blind conditions for 7 successive nights. Polysomnograms were obtained for placebo baseline, beginning and end of DSIP treatment, and one placebo

Dietrich Schneider-Helmert

1987-01-01

18

Delta-sleep-inducing peptide and its analogs and the serotoninergic system in the development of anticonvulsive influences  

Microsoft Academic Search

Experiments on rats were carried out to study the effects of administration of delta-sleep-inducing peptide (DSIP) and its\\u000a analogs (9–14) into the reticular part of the substantia nigra and ventral hippocampus on picrotoxin- and kainate-induced\\u000a epileptic activity. Additionally, the uptake of [3H]tryptophan by brain structures was studied. Intranigral and intrahippocampal microinjections of peptide and its analogs\\u000a were found to have

A. A. Shandra; L. S. Godlevskii; A. I. Brusentsov; V. P. Petrashevich; R. S. Vast’yanov; B. Nikel; I. I. Mikhaleva

1998-01-01

19

Effect of intranigral dosage with delta-sleep-inducing peptide and its analogs on movement and convulsive activity in rats  

Microsoft Academic Search

Studies were carried out in rats on the effects of the administration of delta-sleep-inducing peptide (DSIP) and its analogs\\u000a (1–4) into the reticular part of the substantia nigra on movement and convulsive activity. Intranigral microinjection of DSIP,\\u000a and of DSIP-1 and DSIP-4, reduced horizontal and vertical movement activity as well as excursions to the center of the open\\u000a field. DSIP,

A. A. Shandra; R. S. Godlevskii; A. I. Vast'yanov; A. I. Brusentsov; I. I. Mikhaleva; I. A. Prudchenko; V. N. Zaporozhan

1996-01-01

20

Delta sleep inducing peptide (DSIP): effect on respiration activity in rat brain mitochondria and stress protective potency under experimental hypoxia  

Microsoft Academic Search

Neuromodulatory delta sleep inducing peptide (DSIP) seems to be implicated in the attenuation of stress-induced pathological metabolic disturbances in various animal species and human beings. Mitochondria, as cell organelles, are considered especially sensitive to stress conditions. In this work, the influence of DSIP and Deltaran®—a recently developed product based upon DSIP—on processes of oxidative phosphorylation and ATP production in rat

Elena M. Khvatova; Victor N. Samartzev; Pavel P. Zagoskin; Igor A. Prudchenko; Inessa I. Mikhaleva

2003-01-01

21

Membrane protein crystallization in meso: lipid type-tailoring of the cubic phase.  

PubMed

Hydrated monoolein forms the cubic-Pn3m mesophase that has been used for in meso crystallization of membrane proteins. The crystals have subsequently provided high-resolution structures by crystallographic means. It is possible that the hosting cubic phase created by monoolein alone, which itself is not a common membrane component, will limit the range of membrane proteins crystallizable by the in meso method. With a view to expanding the range of applicability of the method, we investigated by x-ray diffraction the degree to which the reference cubic-Pn3m phase formed by hydrated monoolein could be modified by other lipid types. These included phosphatidylcholine (PC), phosphatidylethanolamine, phosphatidylserine, cardiolipin, lyso-PC, a polyethylene glycol-lipid, 2-monoolein, oleamide, and cholesterol. The results show that all nine lipids were accommodated in the cubic phase to some extent without altering phase identity. The positional isomer, 2-monoolein, was tolerated to the highest level. The least well tolerated were the anionic lipids, followed by lyso-PC. The others were accommodated to the extent of 20-25 mol %. Beyond a certain concentration limit, the lipid additives either triggered one or a series of phase transitions or saturated the phase and separated out as crystals, as seen with oleamide and cholesterol. The series of phases observed and their order of appearance were consistent with expectations in terms of interfacial curvature changes. The changes in phase type and microstructure have been rationalized on the basis of lipid molecular shape, interfacial curvature, and chain packing energy. The data should prove useful in the rational design of cubic phase crystallization matrices with different lipid profiles that match the needs of a greater range of membrane proteins. PMID:12496106

Cherezov, Vadim; Clogston, Jeffrey; Misquitta, Yohann; Abdel-Gawad, Wissam; Caffrey, Martin

2002-12-01

22

Slow Wave Sleep Induced by GABA Agonist Tiagabine Fails to Benefit Memory Consolidation  

PubMed Central

Study Objectives: Slow wave sleep (SWS) plays a pivotal role in consolidating memories. Tiagabine has been shown to increase SWS in favor of REM sleep without impacting subjective sleep. However, it is unknown whether this effect is paralleled by an improved sleep-dependent consolidation of memory. Design: This double-blind within-subject crossover study tested sensitivity of overnight retention of declarative neutral and emotional materials (word pairs, pictures) as well as a procedural memory task (sequence finger tapping) to oral administration of placebo or 10 mg tiagabine (at 22:30). Participants: Fourteen healthy young men aged 21.9 years (range 18-28 years). Measurements and Results: Tiagabine significantly increased the time spent in SWS and decreased REM sleep compared to placebo. Tiagabine also enhanced slow wave activity (0.5-4.0 Hz) and density of < 1 Hz slow oscillations during NREM sleep. Fast (12-15 Hz) and slow (9-12 Hz) spindle activity, in particular that occurring phase-locked to the slow oscillation cycle, was decreased following tiagabine. Despite signs of deeper and more SWS, overnight retention of memory tested after sleep the next evening (19:30) was generally not improved after tiagabine, but on average even lower than after placebo, with this impairing effect reaching significance for procedural sequence finger tapping. Conclusions: Our data show that increasing slow wave sleep with tiagabine does not improve memory consolidation. Possibly this is due to functional differences from normal slow wave sleep, i.e., the concurrent suppressive influence of tiagabine on phase-locked spindle activity. Citation: Feld GB; Wilhelm I; Ma Y; Groch S; Binkofski F; Mölle M; Born J. Slow wave sleep induced by GABA agonist tiagabine fails to benefit memory consolidation. SLEEP 2013;36(9):1317-1326. PMID:23997364

Feld, Gordon B.; Wilhelm, Ines; Ma, Ying; Groch, Sabine; Binkofski, Ferdinand; Molle, Matthias; Born, Jan

2013-01-01

23

Effect of Delta-Sleep-Inducing Peptide on Expression of Heat Shock Protein 70 kDa in K562 Cells  

Microsoft Academic Search

For evaluation of the stress-protective influence of delta-sleep inducing peptide we studied its effects on the system of\\u000a heat-shock proteins in immune cells using the method of flow cytometry. The peptide affected the expression of heat-shock\\u000a protein 70 kDa in cultured human myeloleukemia K562 cells. Delta-sleep-inducing peptide reduces accumulation of intracellular\\u000a heat shock proteins 70 kDa in cells cultured under conditions of

A. A. Nurbakov; I. I. Mikhaleva; A. M. Sapozhnikov

2009-01-01

24

Effects of delta sleep-inducing peptide on pre-and postsynaptic glutamate and postsynaptic GABA receptors in neurons of the cortex, hippocampus, and cerebellum in rats  

Microsoft Academic Search

We studied the effect of delta sleep-inducing peptide on GABA receptors of hippocampal and cerebellar neurons in rats. It\\u000a was shown that delta sleep-inducing peptide considerably and dose-dependently potentiates GABA-activated currents in these\\u000a neurons and blocks NMDA-activated potentiation in cortical and hippocampal neurons. The peptide modulates activity of presynaptic\\u000a NMDA receptors, which is seen from changes in 45Ca2+ uptake into

V. V. Grigor’ev; T. A. Ivanova; E. A. Kustova; L. N. Petrova; T. P. Serkova; S. O. Bachurin

2006-01-01

25

Postresuscitation recovery of functional activity of central nervous system in rats during combination treatment with mexidol and neuropeptides delta sleep-inducing peptide and oxytocin.  

PubMed

In experiments on rats we studied the effects of antioxidant and membrane-protecting agent mexidol and neuropeptides delta sleep-inducing peptide and oxytocin administered during resuscitation after 12-min clinical death. Individual and combination treatment with these substances accelerated recovery of the neurological status and partially or completely corrected behavioral disorders associated with changes in the emotional and motivational status. Combined administration of mexidol and oxytocin most significantly promoted postresuscitation recovery of functional activity in the central nervous system. PMID:14714079

Gorenkova, N A; Nazarenko, I V; Volkov, A V

2003-10-01

26

Effect of delta-sleep inducing peptide-containing preparation Deltaran on biomarkers of aging, life span and spontaneous tumor incidence in female SHR mice  

Microsoft Academic Search

From the age of 3 months until their natural deaths, female Swiss-derived SHR mice were subcutaneously injected 5 consecutive days every month with 0.1 ml of normal saline (control) or with 2.5 ?g\\/mouse (?100 ?g\\/kg) of delta-sleep inducing peptide (DSIP, Trp–Ala–Gly–Gly–Asp–Ala–Ser–Gly–Glu) as the preparation Deltaran® solved in 0.1 ml of saline. There were 54 mice in each group. The results

Irina G. Popovich; Boris O. Voitenkov; Vladimir N. Anisimov; Vadim T. Ivanov; Inessa I. Mikhaleva; Mark A. Zabezhinski; Irina N. Alimova; Dmitri A. Baturin; Natalia Yu. Zavarzina; Svetlana V. Rosenfeld; Anna V. Semenchenko; Anatoli I. Yashin

2003-01-01

27

Efficiency of Ultralow Doses of Antibodies to S100 Protein and Delta Sleep-Inducing Peptide in Rats with Anxious Depression  

Microsoft Academic Search

We studied the effects of single peroral treatment with antibodies against S100 protein and delta sleep-inducing peptide in ultralow doses on behavioral characteristics of rats with anxious depression produced by acute stress (unavoidable electrical shock). Stress-produced behavioral changes and anxiolytic activity of antibodies were determined using the elevated plus-maze, open field, and tail suspension tests. High efficiency of the mixture

L. V. Loskutova; M. B. Shtark; O. I. Epstein

2003-01-01

28

Regulation of free radical processes by delta-sleep inducing peptide in rat tissues under cold stress.  

PubMed

An intraperitoneal injection of an exogenous delta-sleep inducing peptide (DSIP) at a dose of 12 microg/100 g body weight shifted the prooxidant-antioxidant balance of free radical process (FRP) in tissues and erythrocytes of rats: the activities of antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase) and the concentrations of antioxidants (reduced glutathione in particular) increased. The DSIP stimulated the myeloperoxidase activity in blood neutrophils and had no effect on the activity of xanthine oxidase, a prooxidant enzyme, in the brain and liver. Cold stress displaced the prooxidant-antioxidant balance by increasing the xanthine oxidase activity in tissues and decreasing the myeloperoxidase activity in blood neutrophils; it also inhibited the enzyme antioxidant activities in tissues and erythrocytes that was neutralized by an increased ceruloplasmin activity in blood plasma and by an elevated level of antioxidants in rat blood and tissues. Preliminary administration of DSIP to animals exposed to cold stress restored the prooxidant-antioxidant balance: it normalized the myeloperoxidase activity in blood neutrophils, decreased the xanthine oxidase activity, and increased the activity of antioxidant enzymes in tissues and erythrocytes restoring the antioxidant level. The molecular regulation mechanism of free radical processes by DSIP in tissues under stressful conditions is discussed. PMID:11421812

Shustanova, T A; Bondarenko, T I; Milyutina, N P; Mikhaleva, I I

2001-06-01

29

Expression pattern of FOS in orexin neurons during sleep induced by an adenosine A2A receptor agonist.  

PubMed

The present study examined the expression pattern of FOS in the hypothalamic peptide neurons during the sleep-dominant state induced by an adenosine A2A receptor agonist. The control rats, those that received the microdialysis-perfusion of their ventral striatum with artificial cerebrospinal fluid in the dark-active phase, spent 24% of the 90-min period prior to sacrifice in non-rapid eye movement (non-REM) sleep and 2.3% of that in REM sleep. These rats exhibited FOS, a transcription factor, in 21% of their orexin neurons and in 1.0% of their melanin-concentrating hormone (MCH) neurons in the perifornical/lateral hypothalamic areas. However, the rats perfused with 50 microM CGS21680, an adenosine A2A receptor agonist, spent 60% of the 90-min period prior to sacrifice in non-REM sleep and 11% of that in REM sleep. These rats exhibited FOS in 1.7% of their orexin neurons and FOS in 0.5% of their MCH neurons. When the sleep-dominant state was disturbed by mild stimulation and the rats were kept in the sleepy state by treatment with a sleep-inducing dose of CGS21680, the rats exhibited FOS in 13.3% of their orexin neurons, which percentage was about half of that for the control rats. These results suggest that the sleep-promoting process induced by this adenosine A2A receptor agonist was associated with a decline in the activity of orexin neurons. MCH neurons are not likely to change their activities during this sleep-promoting process. PMID:16621044

Satoh, Shinsuke; Matsumura, Hitoshi; Kanbayashi, Takashi; Yoshida, Yasushi; Urakami, Takahito; Nakajima, Tomoko; Kimura, Nobuko; Nishino, Seiji; Yoneda, Hiroshi

2006-06-30

30

Effect of prenatal application of delta-sleep-inducing peptide and prenatal emotional stress on brain monoamine oxidase and on the behavior of adult male progeny of DD mice  

Microsoft Academic Search

Prenatal administration of delta-sleep-inducing peptide (DSIP) at a high dose (120 ?g per 100 g of body weight) and low dose\\u000a (12 ?g per 100 g of body weight) and prenatal emotional stress resulted in aggressive behavior of two-month-old male progeny\\u000a of DD mice in the resident-intruder test. However, no increase in the aggressiveness of male progeny of the highly

N. N. Voitenko

2008-01-01

31

Oat lipids  

Microsoft Academic Search

Oats are a significant world crop. While nutritional interest in food oats has concentrated on oats as a source of dietary\\u000a fiber, the lipid component has both nutritional and technological potential. Thus, the lipid fraction of the oat grain determines\\u000a in large measure its energy content and has a significant impact on nutritional quality. The oat lipids mediate the pasting

Meixue Zhou; Kevin Robards; Malcolm Glennie-Holmes; Stuart Helliwell

1999-01-01

32

[Changes in duodenal lymphoid structures in rats with various behavioral activity, caused by delta sleep-inducing peptide and following acute emotional stress].  

PubMed

The effect of delta sleep-inducing peptide (DSIP) on the lymphoid structures of small intestine, was investigated. Studies were conducted on 42 male Wistar rats, which were previously assessed in an "open field" test. According to the results of the test, rats were divided into behaviorally active animals (prognostically resistant to stress) and passive ones (resistant to the effects of stress). As a stress, immobilization of the animals in pens with an electrical stimulation of their back for 1 hour, was used. Intraperitoneal injection of DSIP resulted in a reduction of eosinophil number in rats of all the experimental groups. After DSIP injection to the active rats of the control group, the increase in small and medium lymphocyte numbers was detected that was more expressed than in the passive rats. After an acute exposure of behaviorally active rats to stress, the number of the cells of lymphoid series was increased,mainly due to the increase in small and medium lymphocytes. In the group of passive rats, stress exposure and DSIP injection resulted in the increase of plasma cell number in all the duodenal mucosa structures studied. PMID:20572393

Ivanova, E A; Koplik, E V

2010-01-01

33

Ether lipids.  

PubMed

The naturally occurring 1-O-alkyl-sn-glycerols and their methoxylated congeners, 1-O-(2'-methoxyalkyl)-sn-glycerols, are biologically active compounds, ubiquitously found in nature as diacyl glyceryl ether lipids and phosphoether lipids. The chief objective of this article is to provide a comprehensive and up to date review on such ether lipids. The occurrence and distribution of these compounds in nature are extensively reviewed, their chemical structure and molecular variety, their biosynthesis and chemical synthesis and, finally, their various biological effects are described and discussed. An unprecedented biosynthesis of the 2'-methoxylated alkylglycerols is proposed. The first synthesis of enantiopure (Z)-(2'R)-1-O-(2'-methoxyhexadec-4'-enyl)-sn-glycerol, the most prevalent 2'-methoxylated type alkylglycerol present in cartilaginous fish, is described. It was accomplished by a highly convergent five step process. PMID:21635876

Magnusson, Carlos D; Haraldsson, Gudmundur G

2011-07-01

34

Lipid Rafts  

Microsoft Academic Search

There has been considerable recent interest in the possibility that the plasma membrane contains lipid “rafts,” microdomains enriched in cholesterol and sphingolipids. It has been suggested that such rafts could play an important role in many cellular processes including signal transduction, membrane trafficking, cytoskeletal organization, and pathogen entry. However, rafts have proven difficult to visualize in living cells. Most of

Sean Munro

2003-01-01

35

Lipid Storage Diseases  

MedlinePLUS

NINDS Lipid Storage Diseases Information Page Condensed from Lipid Storage Diseases Fact Sheet Table of Contents (click to jump to sections) ... Organizations Additional resources from MedlinePlus What are Lipid Storage Diseases? Lipid storage diseases are a group of ...

36

Doxorubicin Lipid Complex Injection  

MedlinePLUS

Doxorubicin lipid complex is used to treat ovarian cancer that has not improved or that has worsened after treatment with other medications. Doxorubicin lipid complex is also used to treat Kaposi's sarcoma ( ...

37

Vincristine Lipid Complex Injection  

MedlinePLUS

Vincristine lipid complex is used to treat a certain type of acute lymphoblastic leukemia (ALL; a type of cancer ... least two different treatments with other medications. Vincristine lipid complex is in a class of medications called ...

38

Daunorubicin Lipid Complex Injection  

MedlinePLUS

Daunorubicin lipid complex is used to treat advanced Kaposi's sarcoma (a type of cancer that causes abnormal tissue to ... body) related to acquired immunodeficiency syndrome (AIDS). Daunorubicin lipid complex is in a class of medications called ...

39

Lipids of Thermoplasma acidophilum  

PubMed Central

Cells of Thermoplasma acidophilum contain about 3% total lipid on a dry weight basis. Total lipid was found to contain 17.5% neutral lipid, 25.1% glycolipid, and 56.6% phospholipid by chromatography on silicic acid. The lipids contain almost no fatty acid ester groups but appear to have long-chain alkyl groups in ether linkages to glycerol. The phospholipid fraction includes a major component which represents about 80% of the lipid phosphorus and 46% of the total lipids. We believe this component to be a long-chain isopranol glycerol diether analogue of glycerolphosphoryl monoglycosyl diglyceride. The glycolipids appear to contain isopranol diether analogues. Several components of the complex, neutral lipid fraction have been identified as hydrocarbons, vitamin K2-7, and isopranol glycerol diether analogues. Sterols are present in the neutral lipids but do not appear to be synthesized by the organism. Images PMID:4344918

Langworthy, Thomas A.; Smith, Paul F.; Mayberry, William R.

1972-01-01

40

Paper chromatography of lipides  

Microsoft Academic Search

Summary  Procedures for qualitative and quantitative paper chromatography of lipides have been described in detail, together with some\\u000a practical applications.\\u000a \\u000a With the monochain lipides it was found that one developing system serves universally. The long aliphatic chains essentially\\u000a determine the chromatographic properties so that suitable conditions for chromatographing any lipide or lipide-like entity\\u000a are predictable. For the same reason total analysis

H. Schlenk; Joanne L. Gellerman; Jerry A. Tillotson; H. K. Mangold

1957-01-01

41

Lipid signalling in disease  

Microsoft Academic Search

Signalling lipids such as eicosanoids, phosphoinositides, sphingolipids and fatty acids control important cellular processes, including cell proliferation, apoptosis, metabolism and migration. Extracellular signals from cytokines, growth factors and nutrients control the activity of a key set of lipid-modifying enzymes: phospholipases, prostaglandin synthase, 5-lipoxygenase, phosphoinositide 3-kinase, sphingosine kinase and sphingomyelinase. These enzymes and their downstream targets constitute a complex lipid signalling

Roger Schneiter; Matthias P. Wymann

2008-01-01

42

Biomolecular archaeology and lipids  

Microsoft Academic Search

Medium?sized biomolecules, particularly lipids, can frequently be detected in ancient materials. The structures and compositions of mixtures of lipids can provide direct evidence for their origin, and hence, evidence for human activity in the past. An important concept in the field of biomolecular archaeology of lipids is that of ‘biomarkers’. Archaeological biomarkers are characteristic compounds (or mixtures of compounds) found

R. P. Evershed

1993-01-01

43

Dynamic transbilayer lipid asymmetry.  

PubMed

Cells have thousands of different lipids. In the plasma membrane, and in membranes of the late secretory and endocytotic pathways, these lipids are not evenly distributed over the two leaflets of the lipid bilayer. The basis for this transmembrane lipid asymmetry lies in the fact that glycerolipids are primarily synthesized on the cytosolic and sphingolipids on the noncytosolic surface of cellular membranes, that cholesterol has a higher affinity for sphingolipids than for glycerolipids. In addition, P4-ATPases, "flippases," actively translocate the aminophospholipids phosphatidylserine and phosphatidylethanolamine to the cytosolic surface. ABC transporters translocate lipids in the opposite direction but they generally act as exporters rather than "floppases." The steady state asymmetry of the lipids can be disrupted within seconds by the activation of phospholipases and scramblases. The asymmetric lipid distribution has multiple implications for physiological events at the membrane surface. Moreover, the active translocation also contributes to the generation of curvature in the budding of transport vesicles. PMID:21436058

van Meer, Gerrit

2011-05-01

44

Epidermal surface lipids  

PubMed Central

A layer of lipids, which are of both sebaceous and keratinocyte origin, covers the surface of the skin. The apparent composition of surface lipids varies depending on the selected method of sampling. Lipids produced by the epidermal cells are an insignificant fraction of the total extractable surface lipid on areas rich in sebaceous glands. Due to the holocrine activity of the sebaceous gland, its product of secretion (sebum) is eventually released to the surface of the skin and coats the fur as well. Lipids of epidermal origin fill the spaces between the cells, like mortar or cement. The sebaceous lipids are primarily non polar lipids as triglycerides, wax esters and squalene, while epidermal lipids are a mixture of ceramides, free fatty acids and cholesterol. The composition of the sebaceous lipids is unique and intriguing and elevated sebum excretion is a major factor involved in the pathophysiology of acne. Recent studies have elucidated the roles that epidermal surface lipids have on normal skin functions and acne. PMID:20224687

2009-01-01

45

Lipids of mitochondria.  

PubMed

A unique organelle for studying membrane biochemistry is the mitochondrion whose functionality depends on a coordinated supply of proteins and lipids. Mitochondria are capable of synthesizing several lipids autonomously such as phosphatidylglycerol, cardiolipin and in part phosphatidylethanolamine, phosphatidic acid and CDP-diacylglycerol. Other mitochondrial membrane lipids such as phosphatidylcholine, phosphatidylserine, phosphatidylinositol, sterols and sphingolipids have to be imported. The mitochondrial lipid composition, the biosynthesis and the import of mitochondrial lipids as well as the regulation of these processes will be main issues of this review article. Furthermore, interactions of lipids and mitochondrial proteins which are highly important for various mitochondrial processes will be discussed. Malfunction or loss of enzymes involved in mitochondrial phospholipid biosynthesis lead to dysfunction of cell respiration, affect the assembly and stability of the mitochondrial protein import machinery and cause abnormal mitochondrial morphology or even lethality. Molecular aspects of these processes as well as diseases related to defects in the formation of mitochondrial membranes will be described. PMID:24007978

Horvath, Susanne E; Daum, Günther

2013-10-01

46

Lipids in Plant Mitochondria  

Microsoft Academic Search

\\u000a Mitochondria perform a variety of fundamental functions and are of pivotal importance in plant physiology and development.\\u000a They possess a typical membrane lipid composition that is largely conserved in all eukaryotes. To establish and maintain their\\u000a lipid pattern, they have to cooperate with other organelles, where a significant portion of their lipids are produced and\\u000a subsequently assembled into the mitochondrial

Radin Sadre; Margrit Frentzen

47

Lipids and lipid metabolism in eukaryotic algae.  

PubMed

Eukaryotic algae are a very diverse group of organisms which inhabit a huge range of ecosystems from the Antarctic to deserts. They account for over half the primary productivity at the base of the food chain. In recent years studies on the lipid biochemistry of algae has shifted from experiments with a few model organisms to encompass a much larger number of, often unusual, algae. This has led to the discovery of new compounds, including major membrane components, as well as the elucidation of lipid signalling pathways. A major drive in recent research have been attempts to discover genes that code for expression of the various proteins involved in the production of very long-chain polyunsaturated fatty acids such as arachidonic, eicosapentaenoic and docosahexaenoic acids. Such work is described here together with information about how environmental factors, such as light, temperature or minerals, can change algal lipid metabolism and how adaptation may take place. PMID:16492482

Guschina, Irina A; Harwood, John L

2006-03-01

48

A lipid transfer protein that transfers lipid.  

PubMed

Very few lipid transfer proteins (LTPs) have been caught in the act of transferring lipids in vivo from a donor membrane to an acceptor membrane. Now, two studies (Halter, D., S. Neumann, S.M. van Dijk, J. Wolthoorn, A.M. de Maziere, O.V. Vieira, P. Mattjus, J. Klumperman, G. van Meer, and H. Sprong. 2007. J. Cell Biol. 179:101-115; D'Angelo, G., E. Polishchuk, G.D. Tullio, M. Santoro, A.D. Campli, A. Godi, G. West, J. Bielawski, C.C. Chuang, A.C. van der Spoel, et al. 2007. Nature. 449:62-67) agree that four-phosphate adaptor protein 2 (FAPP2) transfers glucosylceramide (GlcCer), a lipid that takes an unexpectedly circuitous route. PMID:17923527

Levine, Tim P

2007-10-01

49

Lipid Droplets And Cellular Lipid Metabolism  

PubMed Central

Among organelles, lipid droplets (LDs) uniquely constitute a hydrophobic phase in the aqueous environment of the cytosol. Their hydrophobic core of neutral lipids stores metabolic energy and membrane components, making LDs hubs for lipid metabolism. In addition, LDs are implicated in a number of other cellular functions, ranging from protein storage and degradation to viral replication. These processes are functionally linked to many physiological and pathological conditions, including obesity and related metabolic diseases. Despite their important functions and nearly ubiquitous presence in cells, many aspects of LD biology are unknown. In the past few years, the pace of LD investigation has increased, providing new insights. Here, we review the current knowledge of LD cell biology and its translation to physiology. PMID:22524315

Walther, Tobias C.; Farese, Robert V.

2013-01-01

50

Looking at lipid rafts?  

Microsoft Academic Search

The notion that microdomains enriched in certain specialized lipids exist in membranes has been both attractive and controversial since it was first proposed that such domains, termed rafts, might act as apical sorting devices in epithelial cells. The observation that certain lipids are not extractable in cold non-ionic detergent supports the raft concept, but the nature of the in vivo

Ken Jacobson; Christian Dietrich

1999-01-01

51

Avanti lipid tools: connecting lipids, technology, and cell biology.  

PubMed

Lipid research is challenging owing to the complexity and diversity of the lipidome. Here we review a set of experimental tools developed for the seasoned lipid researcher, as well as, those who are new to the field of lipid research. Novel tools for probing protein-lipid interactions, applications for lipid binding antibodies, enhanced systems for the cellular delivery of lipids, improved visualization of lipid membranes using gold-labeled lipids, and advances in mass spectrometric analysis techniques will be discussed. Because lipid mediators are known to participate in a host of signal transduction and trafficking pathways within the cell, a comprehensive lipid toolbox that aids the science of lipidomics research is essential to better understand the molecular mechanisms of interactions between cellular components. This article is part of a Special Issue entitled Tools to study lipid functions. PMID:24954118

Sims, Kacee H; Tytler, Ewan M; Tipton, John; Hill, Kasey L; Burgess, Stephen W; Shaw, Walter A

2014-08-01

52

Lipids of Debaryomyces hansenii  

PubMed Central

Merdinger, Emanuel (Roosevelt University, Chicago, Ill.), and Edward M. Devine, Jr. Lipids of Debaryomyces hansenii. J. Bacteriol. 89:1488–1493. 1965.—The separation of neutral lipids and phospholipids from the lipid extract of Debaryomyces hansenii NRRL Y-1448 was accomplished by using a single column packed with silicic acid. The neutral lipids comprised 67%, and the phospholipids 33%, of the total lipid extract. Qualitative and quantitative characterization of the lipids was effected by various analytical procedures. Gas chromatography of the fatty acid methyl esters showed 11 acids, of which 59.7% were unsaturated. The most abundant among the unsaturated acids was the monounsaturated C18 acid (50.1%). Among the saturated acids, palmitic acid (23.5%) prevailed. Ratios of fatty acid to glycerol, phosphorus to glycerol, and phosphorus to fatty acid were ascertained for combined cuts from the neutral lipids and the phospholipids. The presence of ergosterol, stigmasterol, and an unidentified sterol was established by gas chromatography. Also present were saturated hydrocarbons containing 16 to 39 carbon atoms, C22 being the most prevalent. PMID:14291585

Merdinger, Emanuel; Devine, Edward M.

1965-01-01

53

Lipid-absorbing Polymers  

NASA Technical Reports Server (NTRS)

The removal of bile acids and cholesterol by polymeric absorption is discussed in terms of micelle-polymer interaction. The results obtained with a polymer composed of 75 parts PEO and 25 parts PB plus curing ingredients show an absorption of 305 to 309%, based on original polymer weight. Particle size effects on absorption rate are analyzed. It is concluded that crosslinked polyethylene oxide polymers will absorb water, crosslinked polybutadiene polymers will absorb lipids; neither polymer will absorb appreciable amounts of lipids from micellar solutions of lipids in water.

Marsh, H. E., Jr.; Wallace, C. J.

1973-01-01

54

Lipids and lysosomes.  

PubMed

Lysosomes are cytoplasmic organelles delimited by a single membrane and filled with a variety of hydrolytic enzymes active at acidic pH and collectively capable to degrade the vast majority of macromolecules entering lysosomes via endocytosis, phagocytosis or autophagy. In this review, we describe the lipid composition and the dynamic properties of lysosomal membrane, the main delivery pathways of lipids to lysosomes and their catabolism inside lysosomes. Then, we present the consequences of a lipid accumulation as seen in various lysosomal storage diseases on lysosomal functions. Finally, we discuss about the possible involvement of lysosomes in lipotoxicity. PMID:22978393

Hamer, Isabelle; Van Beersel, Guillaume; Arnould, Thierry; Jadot, Michel

2012-12-01

55

Direct Visualization of Lipid Phase Segregation in Single Lipid Bilayers  

E-print Network

- servation of lipid rafts in cells remains a challenge. To deepen the understanding of the chemical-Stokes Raman Scattering Microscopy Eric O. Potma and X. Sunney Xie*[a] Lipid rafts, segregated domainsDirect Visualization of Lipid Phase Segregation in Single Lipid Bilayers with Coherent Anti

Potma, Eric Olaf

56

Sleep-Induced Changes in Associative Memory  

Microsoft Academic Search

The notion that dreaming might alter the strength of associative links in memory was first proposed almost 200 years ago. But no strong evidence of such altered associative links has been obtained. Semantic priming can be used to quantify the strength of associative links between pairs of words; it is thought to measure the automatic spread of activation from a

Robert Stickgold; Laurie Scott; Cynthia Rittenhouse; J. Allan Hobson

1999-01-01

57

Focus Issue: Signaling Lipids  

NSDL National Science Digital Library

Membranes are dynamic and specific contributors to cell signaling. Cellular membranes play a key structural role in creating sites for the formation of signaling complexes. Changes in membrane phospholipids can regulate the activity of transmembrane and peripheral membrane proteins. Modification of membrane lipids can result in formation of dynamic signaling molecules. Science's STKE highlights new insights into the roles that lipids and membranes play in cell signaling.

Nancy R. Gough (American Association for the Advancement of Science;Science's STKE REV)

2006-02-07

58

Lipids of Bacteroides melaninogenicus  

PubMed Central

The lipids of Bacteroides melaninogenicus were readily extractable with chloroform-methanol. Three per cent of the fatty acids were not extractable. The neutral lipids contained 4% of the extractable fatty acids, the stench characteristic of these organisms, and 0.5 ?mole of vitamin K2 isoprenologues K2-35, K2-40, and K2-45 per g (dry weight). This is one-fifth to one-tenth of the vitamin K2 level found in other bacteria. Ninety-six per cent of the extractable fatty acids were associated with the phospholipids (60 ?moles of lipid phosphate/g, dry weight), which consisted of the diacyl lipids phosphatidic acid, phosphatidyl serine, and phosphatidyl ethanolamine (with phosphatidyl glycerol and cardiolipin in one strain). The unusual phosphosphingolipids ceramide phosphorylethanolamine, ceramide phosphorylglycerol, and ceramide phosphorylglycerol phosphate accounted for 50 to 70% of the lipid phosphate. In protoheme-requiring strains, the protoheme concentration in the growth medium regulated the growth rate and the amount of enzymatically reducible cytochrome c. There were no gross changes in the lipid composition in cells containing different levels of enzymatically reducible cytochrome c. Images PMID:5411759

Rizza, Victor; Tucker, Anne N.; White, David C.

1970-01-01

59

Acyl-lipid metabolism.  

PubMed

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

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

2013-01-01

60

Acyl-Lipid Metabolism  

PubMed Central

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

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

2010-01-01

61

Acyl-Lipid Metabolism  

PubMed Central

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

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

2013-01-01

62

Nuclear Lipid Signaling  

NSDL National Science Digital Library

The eukaryotic nucleus is surrounded by a double membrane that can be regarded as a part of the endoplasmic reticulum, albeit a specialized part, so it is no particular surprise that lipids are present in nuclei, and that these can change under some conditions. However, what is surprising to many people is that if the nuclear membrane is removed by detergents, there is still a considerable amount of lipid left, and a large number of lipid-synthesizing and metabolizing enzymes. These enzymes are undoubtedly intranuclear, and cannot be discounted as arising from contamination with other cellular fractions. The best characterized of these enzymes are the components of a nuclear polyphosphoinositide cycle that generates phosphatidylinositol-4,5-bisphosphate [PIP2 or PtdIns(4,5)P2]. This PIP2 can in turn be hydrolyzed to diacylglycerol by a phospholipase C (PI-PLC) that is regulated separately from the "classic" plasma membrane PI-PLC. This nuclear diacylglycerol can recruit protein kinase C to the nucleus to phosphorylate substrates (mostly) as yet unidentified. However, that cycle is only the tip of the iceberg, and more and more lipid signaling pathways and players are being implicated as existing within the nucleus. This is a large and confusing literature. This review focuses on the main issues critically assesses the best evidence for what is and is not truly nuclear lipid signaling, and for what such signaling may or may not do.

Robin Irvine (University of Cambridge;Department of Pharmacology REV)

2000-09-05

63

Nuclear Lipid Signaling  

NSDL National Science Digital Library

The eukaryotic nucleus is surrounded by a double membrane that can be regarded as a specialized part of the endoplasmic reticulum, so it is no surprise that lipids are present in nuclei, and that these can change under some conditions. However, what is surprising is that if the nuclear membrane is removed by detergents, there remains a considerable amount of lipid and lipid-synthesizing and metabolizing enzymes. These enzymes are undoubtedly intranuclear, and they cannot be discounted as arising from contamination with other cellular fractions. The best characterized of these enzymes are the components of a nuclear polyphosphoinositide cycle that generates phosphatidylinositol-4,5-bisphosphate [PtdIns(4,5)P2]. This PtdIns(4,5)P2 can in turn be hydrolyzed to diacylglycerol (DAG) by a phospholipase C (PI-PLC) that is regulated separately from the "classic" plasma membrane PI-PLC. This nuclear DAG can recruit protein kinase C from the cytoplasm to the nucleus to phosphorylate substrates, most of which are still unidentified. However, that cycle is only the tip of the iceberg, and more lipid signaling pathways and players are being implicated as existing within the nucleus. This is a large and confusing literature. This review focuses on the main issues and critically assesses the best evidence for what is and is not truly nuclear lipid signaling, and for what such signaling may or may not do.

Robin F. Irvine (University of Cambridge;Department of Pharmacology REV)

2002-09-17

64

Pharmacogenetics of lipid diseases  

PubMed Central

The genetic basis for most of the rare lipid monogenic disorders have been elucidated, but the challenge remains in determining the combination of genes that contribute to the genetic variability in lipid levels in the general population; this has been estimated to be in the range of 40-60 per cent of the total variability. Therefore, the effect of common polymorphisms on lipid phenotypes will be greatly modulated by gene-gene and gene-environment interactions. This approach can also be used to characterise the individuality of the response to lipid-lowering therapies, whether using drugs (pharmacogenetics) or dietary interventions (nutrigenetics). In this regard, multiple studies have already described significant interactions between candidate genes for lipid and drug metabolism that modulate therapeutic response--although the outcomes of these studies have been controversial and call for more rigorous experimental design and analytical approaches. Once solid evidence about the predictive value of genetic panels is obtained, risk and therapeutic algorithms can begin to be generated that should provide an accurate measure of genetic predisposition, as well as targeted behavioural modifications or drugs of choice and personalised dosages of these drugs. PMID:15601539

2004-01-01

65

Immobilized lipid-bilayer materials  

DOEpatents

A method for preparing encapsulated lipid-bilayer materials in a silica matrix comprising preparing a silica sol, mixing a lipid-bilayer material in the silica sol and allowing the mixture to gel to form the encapsulated lipid-bilayer material. The mild processing conditions allow quantitative entrapment of pre-formed lipid-bilayer materials without modification to the material's spectral characteristics. The method allows for the immobilization of lipid membranes to surfaces. The encapsulated lipid-bilayer materials perform as sensitive optical sensors for the detection of analytes such as heavy metal ions and can be used as drug delivery systems and as separation devices.

Sasaki, Darryl Y. (Albuquerque, NM); Loy, Douglas A. (Albuquerque, NM); Yamanaka, Stacey A. (Dallas, TX)

2000-01-01

66

Lipid ion channels.  

PubMed

The interpretation of electrical phenomena in biomembranes is usually based on the assumption that the experimentally found discrete ion conduction events are due to a particular class of proteins called ion channels while the lipid membrane is considered being an inert electrical insulator. The particular protein structure is thought to be related to ion specificity, specific recognition of drugs by receptors and to macroscopic phenomena as nerve pulse propagation. However, lipid membranes in their chain melting regime are known to be highly permeable to ions, water and small molecules, and are therefore not always inert. In voltage-clamp experiments one finds quantized conduction events through protein-free membranes in their melting regime similar to or even undistinguishable from those attributed to proteins. This constitutes a conceptual problem for the interpretation of electrophysiological data obtained from biological membrane preparations. Here, we review the experimental evidence for lipid ion channels, their properties and the physical chemistry underlying their creation. We introduce into the thermodynamic theory of membrane fluctuations from which the lipid channels originate. Furthermore, we demonstrate how the appearance of lipid channels can be influenced by the alteration of the thermodynamic variables (e.g., temperature, pressure, tension and chemical potentials) in a coherent description that is free of parameters. This description leads to pores that display dwell times closely coupled to the fluctuation lifetime via the fluctuation-dissipation theorem. Drugs as anesthetics and neurotransmitters are shown to influence the channel likelihood and their lifetimes in a predictable manner. We also discuss the role of proteins in influencing the likelihood of lipid channel formation. PMID:20385440

Heimburg, T

2010-08-01

67

Lipids of Bryonia alba  

Microsoft Academic Search

The lipid composition of the roots ofBryonia alba (Cucurbitaceae) have been studied: It consists of fractions of 3-acyloxy-24-alkyl(alkenyl)-cholest-7-enes (I), triacylglycerols\\u000a (II), 1,2-diacyl-3-monoglycopyranosyl-sn-glycerols (III), 1,2-diacyl-3-diglycopyranosyl-sn-glycerols (IV), 1,3-bis(3-sn-phosphatidyl)glycerols\\u000a (V), 3-sn-phosphatidylethanolamines (VI), 3-sn-phosphatidylcholines (VII), and methyl esters of fatty acids (VIII). The amount\\u000a of unsaturated fatty acids in the lipid fractions (I–VIII) is 60–94%, the main component being linolenic acid.

A. G. Panosyan; G. M. Avetisyan; M. N. Nikishchenko; V. A. Mnatsakanyan

1980-01-01

68

Discovery and molecular basis of potent noncovalent inhibitors of fatty acid amide hydrolase (FAAH)  

PubMed Central

Fatty acid amide hydrolase (FAAH), an amidase-signature family member, is an integral membrane enzyme that degrades lipid amides including the endogenous cannabinoid anandamide and the sleep-inducing molecule oleamide. Both genetic knock out and pharmacological administration of FAAH inhibitors in rodent models result in analgesic, anxiolytic, and antiinflammatory phenotypes. Targeting FAAH activity, therefore, presents a promising new therapeutic strategy for the treatment of pain and other neurological-related or inflammatory disorders. Nearly all FAAH inhibitors known to date attain their binding potency through a reversible or irreversible covalent modification of the nucleophile Ser241 in the unusual Ser-Ser-Lys catalytic triad. Here, we report the discovery and mechanism of action of a series of ketobenzimidazoles as unique and potent noncovalent FAAH inhibitors. Compound 2, a representative of these ketobenzimidazoles, was designed from a series of ureas that were identified from high-throughput screening. While urea compound 1 is characterized as an irreversible covalent inhibitor, the cocrystal structure of FAAH complexed with compound 2 reveals that these ketobenzimidazoles, though containing a carbonyl moiety, do not covalently modify Ser241. These inhibitors achieve potent inhibition of FAAH activity primarily from shape complementarity to the active site and through numerous hydrophobic interactions. These noncovalent compounds exhibit excellent selectivity and good pharmacokinetic properties. The discovery of this distinctive class of inhibitors opens a new avenue for modulating FAAH activity through nonmechanism-based inhibition. PMID:21502526

Min, Xiaoshan; Thibault, Stephen T.; Porter, Amy C.; Gustin, Darin J.; Carlson, Timothy J.; Xu, Haoda; Lindstrom, Michelle; Xu, Guifen; Uyeda, Craig; Ma, Zhihua; Li, Yihong; Kayser, Frank; Walker, Nigel P. C.; Wang, Zhulun

2011-01-01

69

Synthesis of lipidic tamoxifen  

Microsoft Academic Search

We describe a general method for elaboration of the ethyl sidechain of tamoxifen and its primary 4-hydroxy metabolite. Novel lipidic tamoxifen and a functionalized B-ring analog were synthesized from a common stilbene oxide intermediate for potential liposomal applications including estrogen receptor targeting.

Matthew R Lashley; Michael H Nantz

2000-01-01

70

Structure of lipid bilayers  

PubMed Central

The quantitative experimental uncertainty in the structure of fully hydrated, biologically relevant, fluid (L?) phase lipid bilayers has been too large to provide a firm base for applications or for comparison with simulations. Many structural methods are reviewed including modern liquid crystallography of lipid bilayers that deals with the fully developed undulation fluctuations that occur in the L? phase. These fluctuations degrade the higher order diffraction data in a way that, if unrecognized, leads to erroneous conclusions regarding bilayer structure. Diffraction measurements at high instrumental resolution provide a measure of these fluctuations. In addition to providing better structural determination, this opens a new window on interactions between bilayers, so the experimental determination of interbilayer interaction parameters is reviewed briefly. We introduce a new structural correction based on fluctuations that has not been included in any previous studies. Updated measurements, such as for the area compressibility modulus, are used to provide adjustments to many of the literature values of structural quantities. Since the gel (L??) phase is valuable as a stepping stone for obtaining fluid phase results, a brief review is given of the lower temperature phases. The uncertainty in structural results for lipid bilayers is being reduced and best current values are provided for bilayers of five lipids. PMID:11063882

Nagle, John F.; Tristram-Nagle, Stephanie

2009-01-01

71

Lipids of Viburnum opulus seeds  

Microsoft Academic Search

Lipid components of the seeds ofViburnum opulus (Caprifoliaceae family) were investigated. The neutral lipids consist of eight classes, the glycolipids consist of three classes, and the\\u000a phospholipids contain seven classes. The fatty-acid contents of all of the acyl-containing lipids were determined. The 18?2\\u000a fatty acid is the main component of all the lipid fractions. The content of saturated acids is

S. G. Yunusova; E. G. Zinurova; M. S. Yunusov; E. G. Galkin; A. R. Karimova

1998-01-01

72

Lipid nanotube or nanowire sensor  

DOEpatents

A sensor apparatus comprising a nanotube or nanowire, a lipid bilayer around the nanotube or nanowire, and a sensing element connected to the lipid bilayer. Also a biosensor apparatus comprising a gate electrode; a source electrode; a drain electrode; a nanotube or nanowire operatively connected to the gate electrode, the source electrode, and the drain electrode; a lipid bilayer around the nanotube or nanowire, and a sensing element connected to the lipid bilayer.

Noy, Aleksandr (Belmont, CA); Bakajin, Olgica (San Leandro, CA); Letant, Sonia (Livermore, CA); Stadermann, Michael (Dublin, CA); Artyukhin, Alexander B. (Menlo Park, CA)

2009-06-09

73

Lipid rafts and signal transduction  

Microsoft Academic Search

Signal transduction is initiated by complex protein–protein interactions between ligands, receptors and kinases, to name only a few. It is now becoming clear that lipid micro-environments on the cell surface — known as lipid rafts — also take part in this process. Lipid rafts containing a given set of proteins can change their size and composition in response to intra-

Kai Simons; Derek Toomre

2000-01-01

74

Lysosomal degradation of membrane lipids.  

PubMed

The constitutive degradation of membrane components takes place in the acidic compartments of a cell, the endosomes and lysosomes. Sites of lipid degradation are intralysosomal membranes that are formed in endosomes, where the lipid composition is adjusted for degradation. Cholesterol is sorted out of the inner membranes, their content in bis(monoacylglycero)phosphate increases, and, most likely, sphingomyelin is degraded to ceramide. Together with endosomal and lysosomal lipid-binding proteins, the Niemann-Pick disease, type C2-protein, the GM2-activator, and the saposins sap-A, -B, -C, and -D, a suitable membrane lipid composition is required for degradation of complex lipids by hydrolytic enzymes. PMID:19836391

Kolter, Thomas; Sandhoff, Konrad

2010-05-01

75

Dysregulated lipid metabolism in cancer  

PubMed Central

Alteration of lipid metabolism has been increasingly recognized as a hallmark of cancer cells. The changes of expression and activity of lipid metabolizing enzymes are directly regulated by the activity of oncogenic signals. The dependence of tumor cells on the dysregulated lipid metabolism suggests that proteins involved in this process are excellent chemotherapeutic targets for cancer treatment. There are currently several drugs under development or in clinical trials that are based on specifically targeting the altered lipid metabolic pathways in cancer cells. Further understanding of dysregulated lipid metabolism and its associated signaling pathways will help us to better design efficient cancer therapeutic strategy. PMID:22937213

Zhang, Feng; Du, Guangwei

2012-01-01

76

Topological regulation of lipid balance in cells.  

PubMed

Lipids are unevenly distributed within and between cell membranes, thus defining organelle identity. Such distribution relies on local metabolic branches and mechanisms that move lipids. These processes are regulated by feedback mechanisms that decipher topographical information in organelle membranes and then regulate lipid levels or flows. In the endoplasmic reticulum, the major lipid source, transcriptional regulators and enzymes sense changes in membrane features to modulate lipid production. At the Golgi apparatus, lipid-synthesizing, lipid-flippase, and lipid-transport proteins (LTPs) collaborate to control lipid balance and distribution within the membrane to guarantee remodeling processes crucial for vesicular trafficking. Open questions exist regarding LTPs, which are thought to be lipid sensors that regulate lipid synthesis or carriers that transfer lipids between organelles across long distances or in contact sites. A novel model is that LTPs, by exchanging two different lipids, exploit one lipid gradient between two distinct membranes to build a second lipid gradient. PMID:24606148

Drin, Guillaume

2014-01-01

77

Intestinal lipid absorption  

PubMed Central

Our knowledge of the uptake and transport of dietary fat and fat-soluble vitamins has advanced considerably. Researchers have identified several new mechanisms by which lipids are taken up by enterocytes and packaged as chylomicrons for export into the lymphatic system or clarified the actions of mechanisms previously known to participate in these processes. Fatty acids are taken up by enterocytes involving protein-mediated as well as protein-independent processes. Net cholesterol uptake depends on the competing activities of NPC1L1, ABCG5, and ABCG8 present in the apical membrane. We have considerably more detailed information about the uptake of products of lipid hydrolysis, the active transport systems by which they reach the endoplasmic reticulum, the mechanisms by which they are resynthesized into neutral lipids and utilized within the endoplasmic reticulum to form lipoproteins, and the mechanisms by which lipoproteins are secreted from the basolateral side of the enterocyte. apoB and MTP are known to be central to the efficient assembly and secretion of lipoproteins. In recent studies, investigators found that cholesterol, phospholipids, and vitamin E can also be secreted from enterocytes as components of high-density apoB-free/apoAI-containing lipoproteins. Several of these advances will probably be investigated further for their potential as targets for the development of drugs that can suppress cholesterol absorption, thereby reducing the risk of hypercholesterolemia and cardiovascular disease. PMID:19158321

Iqbal, Jahangir; Hussain, M. Mahmood

2009-01-01

78

Tear film lipids.  

PubMed

Human meibomian gland secretions (MGS, or meibum) are formed from a complex mixture of lipids of different classes such as wax esters, cholesteryl esters, (O-acyl)-?-hydroxy fatty acids (OAHFA) and their esters, acylglycerols, diacylated diols, free fatty acids, cholesterol, and a smaller amount of other polar and nonpolar lipids, whose chemical nature and the very presence in MGS have been a matter of intense debates. The purpose of this review is to discuss recent results that were obtained using different experimental techniques, estimate limitations of their usability, and discuss their biochemical, biophysical, and physiological implications. To create a lipid map of MGS and tears, the results obtained in the author's laboratory were integrated with available information on chemical composition of MGS and tears. The most informative approaches that are available today to researchers, such as HPLC-MS, GC-MS, and proton NMR, are discussed in details. A map of the meibomian lipidome (as it is seen in reverse phase liquid chromatography/mass spectrometry experiments) is presented. Directions of future efforts in the area are outlined. PMID:23769846

Butovich, Igor A

2013-12-01

79

Formation of lipid sheaths around nanoparticle-supported lipid bilayers.  

PubMed

High-surface-area nanoparticles often cluster, with unknown effects on their cellular uptake and environmental impact. In the presence of vesicles or cell membranes, lipid adsorption can occur on the nanoparticles, resulting in the formation of supported lipid bilayers (SLBs), which tend to resist cellular uptake. When the amount of lipid available is in excess compared with that required to form a single-SLB, large aggregates of SLBs enclosed by a close-fitting lipid bilayer sheath are shown to form. The proposed mechanism for this process is one where small unilamellar vesicles (SUVs) adsorb to aggregates of SLBs just above the gel-to-liquid phase transition temperature, T(m) , of the lipids (as observed by dynamic light scattering), and then fuse with each other (rather than to the underlying SLBs) upon cooling below T(m) . The sacks of SLB nanoparticles that are formed are encapsulated by the contiguous close-fitting lipid sheath, and precipitate below T(m) , due to reduced hydration repulsion and the absence of undulation/protrusion forces for the lipids attached to the solid support. The single-SLBs can be released above T(m) , where these forces are restored by the free lipid vesicles. This mechanism may be useful for encapsulation/release of drugs/DNA, and has implications for the toxic effects of nanoparticles, which may be mitigated by lipid sequestration. PMID:22434657

Ahmed, Selver; Savarala, Sushma; Chen, Yanjing; Bothun, Geoffrey; Wunder, Stephanie L

2012-06-11

80

RF Microalgal lipid content characterization  

PubMed Central

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

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

2014-01-01

81

Lipids and Membrane Lateral Organization  

PubMed Central

Shortly after the elucidation of the very basic structure and properties of cellular membranes, it became evident that cellular membranes are highly organized structures with multiple and multi-dimensional levels of order. Very early observations suggested that the lipid components of biological membranes might be active players in the creation of these levels of order. In the late 1980s, several different and diverse experimental pieces of evidence coalesced together giving rise to the lipid raft hypothesis. Lipid rafts became enormously (and, in the opinion of these authors, sometimes acritically) popular, surprisingly not just within the lipidologist community (who is supposed to be naturally sensitive to the fascination of lipid rafts). Today, a PubMed search using the key word “lipid rafts” returned a list of 3767 papers, including 690 reviews (as a term of comparison, searching over the same time span for a very hot lipid-related key word, “ceramide” returned 6187 hits with 799 reviews), and a tremendous number of different cellular functions have been described as “lipid raft-dependent.” However, a clear consensus definition of lipid raft has been proposed only in recent times, and the basic properties, the ruling forces, and even the existence of lipid rafts in living cells has been recently matter of intense debate. The scenario that is gradually emerging from the controversies elicited by the lipid raft hypothesis emphasizes multiple roles for membrane lipids in determining membrane order, that encompass their tendency to phase separation but are clearly not limited to this. In this review, we would like to re-focus the attention of the readers on the importance of lipids in organizing the fine structure of cellular membranes. PMID:21423393

Sonnino, Sandro; Prinetti, Alessandro

2010-01-01

82

Neuroimaging of Lipid Storage Disorders  

ERIC Educational Resources Information Center

Lipid storage diseases, also known as the lipidoses, are a group of inherited metabolic disorders in which there is lipid accumulation in various cell types, including the central nervous system, because of the deficiency of a variety of enzymes. Over time, excessive storage can cause permanent cellular and tissue damage. The brain is particularly…

Rieger, Deborah; Auerbach, Sarah; Robinson, Paul; Gropman, Andrea

2013-01-01

83

Bioactive lipids in metabolic syndrome.  

PubMed

The metabolic syndrome is a cluster of metabolic disorders, such as abdominal obesity, dyslipidemia, hypertension and impaired fasting glucose that contribute to increased cardiovascular morbidity and mortality. Although the pathogenesis of metabolic syndrome is complicated and the precise mechanisms have not been elucidated, dietary lipids have been recognized as contributory factors in the development and the prevention of cardiovascular risk clustering. This review explores the physiological functions and molecular actions of bioactive lipids, such as n-3 polyunsaturated fatty acids, conjugated fatty acids, sterols, medium-chain fatty acids, diacylglycerols and phospholipids, in the development of metabolic syndrome. Dietary bioactive lipids suppress the accumulation of abdominal adipose tissue and lipids in the liver and serum, and alleviate hypertension and type 2 diabetes through the transcriptional regulation of lipid and glucose metabolism. Peroxisome proliferator-activated receptors (PPARs), sterol regulatory element binding proteins, liver X receptor alpha, retinoid X receptor alpha, farnesoid X receptor alpha, hepatic nuclear factor 4alpha and nuclear factor kappaB contribute to these nuclear actions of bioactive lipids with complex interactions. Recent studies have demonstrated the striking ability of bioactive lipids to regulate the production of physiologically active adipocytokines through PPARgamma activation. In particular, the function of bioactive lipids as dietary adiponectin inducers (dietary insulin sensitizers) deserves attention with respect to alleviation of metabolic syndrome by dietary manipulation. PMID:18177744

Nagao, Koji; Yanagita, Teruyoshi

2008-03-01

84

Big, Fat World of Lipids  

MedlinePLUS

... The Big, Fat World of Lipids Inside Life Science View All Articles | Inside Life Science Home Page The Big, Fat World of Lipids ... Fats Do in the Body? This Inside Life Science article also appears on LiveScience . Learn about related ...

85

Analysis of caulobacter crescentus lipids.  

PubMed Central

The lipids of Caulobacter crescentus, a procaryotic species which differentiates into stalked and swarmer cell types, were analyzed. Major lipid classes were purified by chromatography and identified by both chromatographic and chemical methods. Approximately half of the total lipid fraction of this organism consisted of glycolipis, which were primarily monoglucosyldiglyceride and an acylated glucuronic acid. Two of the phospholipids of C. crescentus were identified as phopshatidylglycerol and acylphosphatidylglycerol. Commonly occurring bacterial phospholipids, such as phosphatidylethanolamine and cardiolipin (diphosphatidylglycerol), were not detected. Monoglyceride and diglyceride were found in the neutral lipid fraction, which made up 10% of the total lipid. Quantitative lipid compositional studies, performed by the incorporation of [14C]acetate and [32P]orthophosphate into growing cultures, revealed that separated swarmer and stalked cells had similar lipid compositions. However, stationary-phase cultures, compared with logaritmic cultures, had decreased amounts of phosphatidylglycerol and diglyceride and increased amounts of acylphosphatidylglycerol and a glucuronic acid-containing glycolipid, glycolipid X. In addition, two glycolipids were only detected in stationary-phase cultures. These studies indicate that C. crescentus has a distinctive lipid composition compared with those of other procaryotic species which have been analyzed. Images PMID:7410318

De Siervo, A J; Homola, A D

1980-01-01

86

Epidemiologic aspects of lipid abnormalities  

Microsoft Academic Search

Existing cholesterol guidelines aimed at preventing cardiovascular disease emphasize the role of total cholesterol (TC) and low-density lipoprotein (LDL) cholesterol in lipid management decisions, with a subsidiary role for high-density lipoprotein (HDL) cholesterol in guiding treatment and little role for triglycerides. In this article, epidemiologic evidence is reviewed relating to the independent value of lipid factors in prediction of cardiovascular

Michael H Criqui; Beatrice A Golomb

1998-01-01

87

Lipid Rafts Reconstituted in Model Membranes  

Microsoft Academic Search

One key tenet of the raft hypothesis is that the formation of glycosphingolipid- and cholesterol-rich lipid domains can be driven solely by characteristic lipid-lipid interactions, suggesting that rafts ought to form in model membranes composed of appropriate lipids. In fact, domains with raft-like properties were found to coexist with fluid lipid regions in both planar supported lipid layers and in

C. Dietrich; L. A. Bagatolli; Z. N. Volovyk; N. L. Thompson; M. Levi; K. Jacobson; E. Gratton

2001-01-01

88

Renal lipid metabolism and lipotoxicity  

PubMed Central

Purpose of review Lipid accumulation in nonadipose tissues is increasingly recognized to contribute to organ injury through a process termed lipotoxicity, but whether this process occurs in the kidney is still uncertain. This article briefly summarizes the normal role of lipids in renal physiology and the current evidence linking excess lipids and lipotoxicity to renal dysfunction. Recent findings Evidence suggesting that renal lipid accumulation and lipotoxicity may lead to kidney dysfunction has mounted significantly over recent years. Abnormal renal lipid content has been described in a number of animal models and has been successfully manipulated using pharmacologic or genetic strategies. There is some heterogeneity among studies with regard to the mechanisms, consequences, and localization of lipid accumulation in the kidney, explainable at least in part by inherent differences between animal models. The relevance of these findings for human pathophysiology remains to be established. Summary Current knowledge on renal lipid physiology and pathophysiology is insufficient, but provides a strong foundation and incentive for further exploration. The future holds significant challenges in this area, especially with regard to applicability of research findings to the human kidney in vivo, but also the opportunity to transform our understanding of an array of kidney disorders. PMID:20489613

Bobulescu, Ion Alexandru

2011-01-01

89

Volumetric Stability of Lipid Bilayers  

PubMed Central

In agreement with recent reports, a commercial densimeter has yielded a gradual decrease in lipid molecular volume of DPPC multilamellar vesicle dispersions in the gel phase upon repeated thermal cycling between 10ºC and 50ºC. The considerable size of this decrease would have significant implications for the physical chemistry of biomembranes. In contrast, neutral buoyancy measurements performed with similar thermal cycling indicate no gradual change in lipid volume in the gel phase at 20ºC. Remixing the lipid in the densimeter shows that the apparent volume decrease is an artifact. We conclude that gel phase DPPC bilayers exist in a volumetrically stable phase. PMID:23069984

Hallinen, Kelsey M.; Tristram-Nagle, Stephanie

2012-01-01

90

The other lipids: Ectopic lipids with emphasis on skeletal muscle  

Microsoft Academic Search

The obesity pandemic has intensified research into the multifaceted functions of adipose tissues. Recent studies are revealing\\u000a an intricate intercellular and intracellular system of lipid signaling between adipose tissue and other major peripheral organs\\u000a to control energy flux. If not controlled, minor disturbances can lead to deleterious ectopic lipids deposition with unwanted\\u000a health consequences. The pathophysiology of obesity is associated

Lan Chi T. Luu; Eric Ravussin

2008-01-01

91

Lipid Composition of Mycoplasma neurolyticum  

PubMed Central

The total lipid content of Mycoplasma neurolyticum comprises about 14% of the dry weight of the organisms and is about equally distributed between the phospholipid and the neutral-glycolipid fractions. The neutral lipids were identified as triglycerides, diglycerides, and cholesterol. The glycolipid fraction contained 1-O-?-glucopyranosyl-d-2,3-diglyceride and 1-[O-?-d-glycopyranosyl-(1?6)-O-?-d-glucopyranosyl]-d-2,3-diglyceride. The latter lipid is structurally identical to the diglucosyl diglyceride which occurs in Staphylococcus aureus. The phospholipids of the organism consist of a fully acylated glycerophosphoryl-glycerophosphoryl glycerol, phosphatidic acid, diphosphatidyl glycerol, phosphatidyl glycerol, and amino acyl esters of phosphatidyl glycerol. Phosphatidic acid and phosphatidyl glycerol account for greater than 90% of the phospholipids of organisms in the exponential phase of growth. The predominant fatty acids found in all of the acyl lipids were palmitic, stearic, and oleic acids. Images PMID:5079074

Smith, Paul F.

1972-01-01

92

Microrheology of freestanding lipid bilayers  

NASA Astrophysics Data System (ADS)

The macroscopic material properties of cellular membranes, determined by the composition and interactions of their constituent lipids, are important factors in the structure and function of all living cells. Fluidity is a key material property of membranes, yet the underlying lipid bilayer viscosity and other rheological parameters remain poorly quantified. We adopt recently developed microrheological methods to study multiple composite freestanding ``black'' lipid membranes. Using high speed video particle tracking, we monitor dynamics of membrane-anchored nano- and micro-particles across a range of temperatures that span bilayer phase transitions. Two particle spatial correlation functions and the complex shear modulus are extracted from such measurements and provide information about fundamental membrane material properties. We find striking and previously unreported signatures of viscoelasticity in these lipid bilayers whose properties are sensitive to the bilayers' temperature dependent liquid ordered to liquid disordered phase transitions.

Harland, Christopher; Bradley, Miranda; Parthasarathy, Raghuveer

2010-03-01

93

The role of lipids in pulmonary surfactant  

Microsoft Academic Search

Pulmonary surfactant is composed of approx. 90% lipids and 10% protein. This review article focusses on the lipid components of surfactant. The first sections will describe the lipid composition of mammalian surfactant and the techniques that have been utilized to study the involvement of these lipids in reducing the surface tension at an air-liquid interface, the main function of pulmonary

Ruud Veldhuizen; Kaushik Nag; Sandra Orgeig; Fred Possmayer

1998-01-01

94

LIPID PROFILE IN ALCOHOL DEPENDENCE  

PubMed Central

Fifty three patients of alcohol dependence were studied for lipid profile at Drug Dependence Treatment Centre, A.I.I.M.S. Statistically significant differences were observed on most of lipid profile indicators when compared to control group. Ratio of Apo A-I & Apo B appeared to be better indicator than Apo A1 or Apo B. The findings of the study are discussed in context of other studies from India and other countries. PMID:21584039

Vaswani, M.; Hemraj, P.; Desai, N.G.; Tripathi, B.M.

1997-01-01

95

Smart Lipids for Programmable Nanomaterials  

PubMed Central

Novel, responsive liposomes are introduced, assembled from DNA-programmed lipids allowing sequence selective manipulation of nanoscale morphology. Short, single stranded DNA sequences form polar head groups conjugated to hydrophobic tails. The morphology of the resulting lipid aggregates depends on sterics and electronics in the polar head groups and therefore, is dependent on the DNA hybridization state. The programmability, specificity and reversibility of the switchable system are demonstrated via dynamic light scattering, transmission electron microscopy and fluorescence microscopy. PMID:20518544

Thompson, Matthew P.; Chien, Miao-Ping; Ku, Ti-Hsuan; Rush, Anthony M.; Gianneschi, Nathan C.

2010-01-01

96

Cubic phases in membrane lipids.  

PubMed

On the basis of data obtained by time-resolved X-ray diffraction, we consider in the present article the occurrence and formation pathways of inverted bicontinuous cubic phases, or bilayer cubic phases, Q (II)(B) , in diluted dispersions of lipids representing major biomembrane lipid classes [phosphatidylethanolamines (PEs), mixtures of PEs and phosphatidylcholines (PCs) with other lipids, glycolipids]. We show that Q (II)(B) formation proceeds much more easily upon cooling from the H(II) phase than upon heating or isothermal conversion from the L(?) phase, thus identifying an indirect but faster route for Q (II)(B) phase induction in lipids. The data collected consistently show that the ability to convert into cubic phase upon temperature cycling appears to be a general property of all lipids exhibiting an L(?) ? H(II) phase transition. Admixtures of charged phospholipids, both anionic and cationic, strongly facilitate Q (II)(B) formation in PEs. Their effect may be attributed to increased electrostatic repulsion between the lipid bilayers that reduces the unbinding energy and facilitates the dissipation of the L(?) phase required for its conversion into bilayer cubic phase. PMID:22584384

Tenchov, Boris; Koynova, Rumiana

2012-10-01

97

Extraction of lipids from Mortierella alpina and enrichment of arachidonic acid from the fungal lipids  

Microsoft Academic Search

Mortierella alpina is known as an arachidonic acid (AA) producing oleaginous fungus. Extraction of lipids from wet and dry M. alpina biomass was compared. Lipids yield of extraction from dry cells was higher than that of extraction from wet. Wet extraction mainly extracted lipid bodies and lipids in membranes did not extract effectively. Enrichment of AA from the fungal lipids

M. Zhu; P. P. Zhou; L. J. Yu

2002-01-01

98

Exogenous Ether Lipids Predominantly Target Mitochondria  

Microsoft Academic Search

Ether lipids are ubiquitous constituents of cellular membranes with no discrete cell biological function assigned yet. Using fluorescent polyene-ether lipids we analyzed their intracellular distribution in living cells by microscopy. Mitochondria and the endoplasmic reticulum accumulated high amounts of ether-phosphatidylcholine and ether-phosphatidylethanolamine. Both lipids were specifically labeled using the corresponding lyso-ether lipids, which we established as supreme precursors for lipid

Lars Kuerschner; Doris Richter; Hans Kristian Hannibal-Bach; Anne Gaebler; Andrej Shevchenko; Christer S. Ejsing; Christoph Thiele

2012-01-01

99

Effects of Lipopolysaccharide, Lipid A, Lipid X, and Phorbol Ester on Cultured Bovine Endothelial Cells,  

National Technical Information Service (NTIS)

In pursuing the mechanism of endotoxin action, we examined the effect of lipopolysaccharide (LPS) and its chemically defined components, lipid A and lipid X on cultured bovine endothelial cells. We report that LPS and lipid A caused detachment and altered...

S. L. Gartner, D. G. Sieckmann, Y. H. Kang, L. P. Watson, L. D. Homer

1988-01-01

100

Polyunsaturated eicosapentaenoic acidchanges lipid composition in lipid rafts  

Microsoft Academic Search

Summary\\u000a Background  Polyunsaturated\\u000a fatty acids (PUFAs) modulate\\u000a immune responses particularly\\u000a by affecting T cell function\\u000a and are applied clinically as adjuvant\\u000a immunosuppressants in the\\u000a treatment of various inflammatory\\u000a diseases. However, the molecular\\u000a mechanisms of PUFA–induced immunosuppressive\\u000a effects are not\\u000a yet elucidated. Membrane lipid\\u000a rafts are functional plasma membrane\\u000a microdomains characterized\\u000a by a unique lipid environment.\\u000a Since lipid interactions are crucial\\u000a for

Qiurong Li; Li Tan; Chang Wang; Ning Li; Yousheng Li; Guowang Xu; Jieshou Li

2006-01-01

101

Oral retinoids and plasma lipids.  

PubMed

Retinoids and rexinoids are prescribed for conditions ranging from acne vulgaris to hyperkeratosis to cutaneous T cell lymphoma. Dyslipidemia is a frequent consequence of the use of these drugs, with more than one-third of patients manifesting aberrations in triglyceride (TG) levels. The efficacy of retinoic acid derivatives is linked to their influence on lipid metabolism in the skin, which can impair systemic lipid trafficking and metabolism in some patients. Thus, baseline screening for preexisting dyslipidemia and regular follow-up lipid panels are mandated, especially when powerful agents such as bexarotene are used. Dietary modification, increased physical activity, and weight management are the cornerstones of initial management for mild hypertriglyceridemia, which is a contributor to cardiovascular risk. More severe impairments (fasting TG > 500?mg/dL) warrant pharmacologic interventions early on to reduce the risk of pancreatitis. Retinoic acid derivative action, lipid metabolism, and treatment of incident dyslipidemias are reviewed to empower prescribers in management of adverse lipid effects. PMID:24099071

Lilley, Jessica S; Linton, Macrae F; Fazio, Sergio

2013-01-01

102

Nonvesicular Lipid Transfer from the Endoplasmic Reticulum  

PubMed Central

The transport of lipids from their synthesis site at the endoplasmic reticulum (ER) to different target membranes could be mediated by both vesicular and nonvesicular transport mechanisms. Nonvesicular lipid transport appears to be the major transport route of certain lipid species, and could be mediated by either spontaneous lipid transport or by lipid-transfer proteins (LTPs). Although nonvesicular lipid transport has been extensively studied for more than four decades, its underlying mechanism, advantage and regulation, have not been fully explored. In particular, the function of LTPs and their involvement in intracellular lipid movement remain largely controversial. In this article, we describe the pathways by which lipids are synthesized at the ER and delivered to different cellular membranes, and discuss the role of LTPs in lipid transport both in vitro and in intact cells. PMID:23028121

Lev, Sima

2012-01-01

103

Yeast lipid metabolism at a glance.  

PubMed

During the last decades, lipids have gained much attention due to their involvement in health and disease. Lipids are required for the formation of membranes and contribute to many different processes such as cell signaling, energy supply, and cell death. Various organelles such as the endoplasmic reticulum, mitochondria, peroxisomes, and lipid droplets are involved in lipid metabolism. The yeast Saccharomyces cerevisiae has become a reliable model organism to study biochemistry, molecular biology, and cell biology of lipids. The availability of mutants bearing defects in lipid metabolic pathways and the ease of manipulation by culture conditions facilitated these investigations. Here, we summarize the current knowledge about lipid metabolism in yeast. We grouped this large topic into three sections dealing with (1) fatty acids; (2) membrane lipids; and (3) storage lipids. Fatty acids serve as building blocks for the synthesis of membrane lipids (phospholipids, sphingolipids) and storage lipids (triacylglycerols, steryl esters). Phospholipids, sterols, and sphingolipids are essential components of cellular membranes. Recent investigations addressing lipid synthesis, degradation, and storage as well as regulatory aspects are presented. The role of enzymes governing important steps of the different lipid metabolic pathways is described. Finally, the link between lipid metabolic and dynamic processes is discussed. PMID:24520995

Klug, Lisa; Daum, Günther

2014-05-01

104

Lipids and the ocular lens  

PubMed Central

The unusually high levels of saturation and thus order contribute to the uniqueness of human lens membranes. In addition, and unlike in most biomembranes, most of the lens lipids are associated with proteins, thus reducing their mobility. The major phospholipid of the human lens is dihydrosphingomyelin. Found in significant quantities only in primate lenses, particularly human ones, this lipid is so extremely stable that it was reported to be the only lipid remaining in a frozen mammoth 40,000 years after its death. Unusually high levels of cholesterol add peculiarity to the composition of lens membranes. Beyond the lateral segregation of lipids into dynamic domains known as rafts, the high abundance of cholesterol in the human lens leads to the formation of patches of pure cholesterol. Changes in human lens lipid composition with age and disease as well as differences among species are greater than those observed for any other biomembrane. The relationships among lens membrane composition, structure, and lipid conformation reviewed in this article are unique to the mammalian lens and offer exciting insights into lens membrane function. This review focuses on findings reported over the last two decades that demonstrate the uniqueness of mammalian lens membranes regarding their morphology and composition. Becaue the membranes of human lenses do undergo the most dramatic changes with age and cataractogenesis, the final sections of this review address our current knowledge of the unusual composition and organization of adult human lens membranes with and without opacification. Finally, the questions that still remain to be answered are presented. PMID:20407021

Borchman, Douglas; Yappert, Marta C.

2010-01-01

105

Charge-reversal Lipids, Peptide-based Lipids, and Nucleoside-based Lipids for Gene Delivery  

PubMed Central

Conspectus Twenty years after gene therapy was introduced in the clinic, advances in the technique continue to garner headlines as successes pique the interest of clinicians, researchers, and the public. Gene therapy’s appeal stems from its potential to revolutionize modern medical therapeutics by offering solutions to a myriad of diseases by tailoring the treatment to a specific individual’s genetic code. Both viral and non-viral vectors have been used in the clinic, but the low transfection efficiencies when utilizing non-viral vectors have lead to an increased focus on engineering new gene delivery vectors. To address the challenges facing non-viral or synthetic vectors, specifically lipid-based carriers, we have focused on three main themes throughout our research: 1) that releasing the nucleic acid from the carrier will increase gene transfection; 2) that utilizing biologically inspired designs, such as DNA binding proteins, to create lipids with peptide-based headgroups will improve delivery; and 3) that mimicking the natural binding patterns observed within DNA, by using lipids having a nucleoside headgroup, will give unique supramolecular assembles with high transfection efficiency. The results presented in this Account demonstrate that cellular uptake and transfection efficacy can be improved by engineering the chemical components of the lipid vectors to enhance nucleic acid binding and release kinetics. Specifically, our research has shown that the incorporation of a charge-reversal moiety to initiate change of the lipid from positive to negative net charge during the transfection process improves transfection. In addition, by varying the composition of the spacer (rigid, flexible, short, long, and aromatic) between the cationic headgroup and the hydrophobic chains, lipids can be tailored to interact with different nucleic acids (DNA, RNA, siRNA) and accordingly affect delivery, uptake outcomes, and transfection efficiency. Introduction of a peptide headgroup into the lipid provides a mechanism to affect the binding of the lipid to the nucleic acid, to influence the supramolecular lipoplex structure, and to enhance gene transfection activity. Lastly, we discuss the in-vitro successes we have had when using lipids possessing a nucleoside headgroup to create unique self-assembled structures and to deliver DNA to cells. In this Account, we state our hypotheses and design elements as well as describe the techniques that we have utilized in our research, in order to provide readers with the tools to characterize and engineer new vectors. PMID:22439686

LaManna, Caroline M.; Lusic, Hrvoje; Camplo, Michel; McIntosh, Thomas J.; Barthelemy, Philippe; Grinstaff, Mark W.

2013-01-01

106

Charge-reversal lipids, peptide-based lipids, and nucleoside-based lipids for gene delivery.  

PubMed

Twenty years after gene therapy was introduced in the clinic, advances in the technique continue to garner headlines as successes pique the interest of clinicians, researchers, and the public. Gene therapy's appeal stems from its potential to revolutionize modern medical therapeutics by offering solutions to myriad diseases through treatments tailored to a specific individual's genetic code. Both viral and non-viral vectors have been used in the clinic, but the low transfection efficiencies when non-viral vectors are used have lead to an increased focus on engineering new gene delivery vectors. To address the challenges facing non-viral or synthetic vectors, specifically lipid-based carriers, we have focused on three main themes throughout our research: (1) The release of the nucleic acid from the carrier will increase gene transfection. (2) The use of biologically inspired designs, such as DNA binding proteins, to create lipids with peptide-based headgroups will improve delivery. (3) Mimicking the natural binding patterns observed within DNA, by using lipids having a nucleoside headgroup, will produce unique supramolecular assembles with high transfection efficiencies. The results presented in this Account demonstrate that engineering the chemical components of the lipid vectors to enhance nucleic acid binding and release kinetics can improve the cellular uptake and transfection efficacy of nucleic acids. Specifically, our research has shown that the incorporation of a charge-reversal moiety to initiate a shift of the lipid from positive to negative net charge improves transfection. In addition, by varying the composition of the spacer (rigid, flexible, short, long, or aromatic) between the cationic headgroup and the hydrophobic chains, we can tailor lipids to interact with different nucleic acids (DNA, RNA, siRNA) and accordingly affect delivery, uptake outcomes, and transfection efficiency. The introduction of a peptide headgroup into the lipid provides a mechanism to affect the binding of the lipid to the nucleic acid, to influence the supramolecular lipoplex structure, and to enhance gene transfection activity. Lastly, we discuss the in vitro successes that we have had when using lipids possessing a nucleoside headgroup to create unique self-assembled structures and to deliver DNA to cells. In this Account, we state our hypotheses and design elements as well as describe the techniques that we have used in our research to provide readers with the tools to characterize and engineer new vectors. PMID:22439686

LaManna, Caroline M; Lusic, Hrvoje; Camplo, Michel; McIntosh, Thomas J; Barthélémy, Philippe; Grinstaff, Mark W

2012-07-17

107

Mast cells: from lipid droplets to lipid mediators  

PubMed Central

LDs (lipid droplets) are metabolically highly active intracellular organelles. The lipid and protein profiles of LDs are cell-type-specific, and they undergo dynamic variation upon changes in the physiological state of a cell. It is well known that the main function of the LDs in adipocytes is to ensure energy supply and to maintain lipid homoeostasis in the body. In contrast, LDs in inflammatory cells have been implicated in eicosanoid biosynthesis, particularly under inflammatory conditions, thereby enabling them to regulate immune responses. Human mast cells are potent effector cells of the innate immune system, and the triacylglycerol (triglyceride) stores of their cytoplasmic LDs have been shown to contain large amounts of arachidonic acid, the main precursor of pro-inflammatory eicosanoids. In the present review, we discuss the current knowledge about the formation and function of LDs in inflammatory cells with specific emphasis on arachidonic acid and eicosanoid metabolism. On the basis of findings reported previously and our new observations, we propose a model in which lipolysis of LD-triacylglycerols provides arachidonic acid for lipid mediator generation in human mast cells. PMID:23577635

Dichlberger, Andrea; Kovanen, Petri T.; Schneider, Wolfgang J.

2013-01-01

108

Mast cells: from lipid droplets to lipid mediators.  

PubMed

LDs (lipid droplets) are metabolically highly active intracellular organelles. The lipid and protein profiles of LDs are cell-type-specific, and they undergo dynamic variation upon changes in the physiological state of a cell. It is well known that the main function of the LDs in adipocytes is to ensure energy supply and to maintain lipid homoeostasis in the body. In contrast, LDs in inflammatory cells have been implicated in eicosanoid biosynthesis, particularly under inflammatory conditions, thereby enabling them to regulate immune responses. Human mast cells are potent effector cells of the innate immune system, and the triacylglycerol (triglyceride) stores of their cytoplasmic LDs have been shown to contain large amounts of arachidonic acid, the main precursor of pro-inflammatory eicosanoids. In the present review, we discuss the current knowledge about the formation and function of LDs in inflammatory cells with specific emphasis on arachidonic acid and eicosanoid metabolism. On the basis of findings reported previously and our new observations, we propose a model in which lipolysis of LD-triacylglycerols provides arachidonic acid for lipid mediator generation in human mast cells. PMID:23577635

Dichlberger, Andrea; Kovanen, Petri T; Schneider, Wolfgang J

2013-08-01

109

Lipids of Sarcina lutea III. Composition of the Complex Lipids  

PubMed Central

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

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

1965-01-01

110

Exogenous Ether Lipids Predominantly Target Mitochondria  

PubMed Central

Ether lipids are ubiquitous constituents of cellular membranes with no discrete cell biological function assigned yet. Using fluorescent polyene-ether lipids we analyzed their intracellular distribution in living cells by microscopy. Mitochondria and the endoplasmic reticulum accumulated high amounts of ether-phosphatidylcholine and ether-phosphatidylethanolamine. Both lipids were specifically labeled using the corresponding lyso-ether lipids, which we established as supreme precursors for lipid tagging. Polyfosine, a fluorescent analogue of the anti-neoplastic ether lipid edelfosine, accumulated to mitochondria and induced morphological changes and cellular apoptosis. These data indicate that edelfosine could exert its pro-apoptotic power by targeting and damaging mitochondria and thereby inducing cellular apoptosis. In general, this study implies an important role of mitochondria in ether lipid metabolism and intracellular ether lipid trafficking. PMID:22348073

Kuerschner, Lars; Richter, Doris; Hannibal-Bach, Hans Kristian; Gaebler, Anne; Shevchenko, Andrej; Ejsing, Christer S.; Thiele, Christoph

2012-01-01

111

Substrate-supported lipid nanotube arrays.  

PubMed

This Communication describes the self-assembly of phospholipids into lipid nanotubes inside nanoporous anodic aluminum oxide substrate. Orientations of the lipid molecules in such lipid nanoscale structures were verified by high-resolution spin labeling EPR at 95 GHz. The static order parameter of lipids in such nanotube arrays was determined from low-temperature EPR spectra and was found to be exceptionally high, Sstatic approximately 0.9. We propose that substrate-supported lipid nanotube arrays have potential for building robust biochips and biosensors in which rigid nanoporous substrates protect the bilayer surface from contamination. The total bilayer surface in the lipid nanotube arrays is much greater than that in the planar substrate-supported membranes. The lipid nanotube arrays seem to be suitable for developing patterned lipid deposition and could be potentially used for patterning of membrane-associated molecules. PMID:12848539

Smirnov, Alex I; Poluektov, Oleg G

2003-07-16

112

Lipid-coated nanocapillaries for DNA sensing.  

PubMed

We report a simple and efficient way to accomplish the chemical modification of glass nanopores by means of lipid self-assembly. Lipid coating improves the success rate of these glass nanopores as biosensors to detect ?-DNA. PMID:23148206

Hernández-Ainsa, Silvia; Muus, Christoph; Bell, Nicholas A W; Steinbock, Lorenz J; Thacker, Vivek V; Keyser, Ulrich F

2013-01-01

113

Stabilization of Lipid Membranes With Dendritic Polymers.  

National Technical Information Service (NTIS)

Ion channels incorporated into lipid bilayers can be used as chemical sensors; however, the lack of stability of these bilayers prevents their use in practical sensor devices. In this study, dendrimers were used to stabilize lipid membranes by making use ...

J. J. LaScala, P. Pokhrel, L. T. Piehler, G. Mallick, S. Karna

2004-01-01

114

Lipid determinants of cell death.  

PubMed

Lipids produced by the epidermis serve a number of protective functions, and also act as messengers which activate plant defense responses. The fatty acid elongases which catalyze the formation of very long-chain fatty acids, may be instrumental in the remodeling of the various classes of epidermal lipids, and they also provide a means with which to further investigate the defense mechanisms. In a recent publication, we reported that the epidermal mis-expression of FATTY ACID ELONGASE1 (FAE1) in the Arabidopsis plant both increased the levels of very long-chain fatty acids in various lipid classes, and unexpectedly induced a cell-type specific cell death program in trichome cells, giving the plants a glabrous appearance. Using these plants as a model system for a fatty acid-induced cell death (lipoapoptosis), and a platform for the chemical genetic screen, we identified trichome death inhibitors in the glycerophospholipid fatty acyl remodeling pathway: phospholipase A2 inhibitors, aristolochic acid and bromoenol lactone, as well as the putative lysophospholipid acyltransferase inhibitor, clofibrate. Herein, and due to space limitations, we will briefly discuss these results and the different ways in which the appearance of increasing chain-length fatty acids is likely to regulate the cellular life-or-death switch. The death receptor hypothesis implies the existence of a bioactive lipid ligand(s), the functionality of which is determined by phosphorylation, acyl chain length and saturation. PMID:19820339

Reina-Pinto, José J; Yephremov, Alexander

2009-07-01

115

Wave Propagation in Lipid Monolayers  

E-print Network

Sound waves are excited on lipid monolayers using a set of planar electrodes aligned in parallel with the excitable medium. By measuring the frequency dependent change in the lateral pressure we are able to extract the sound velocity for the entire monolayer phase diagram. We demonstrate that this velocity can also be directly derived from the lipid monolayer compressibility and consequently displays a minimum in the phase transition regime. This minimum decreases from v0=170m/s for one component lipid monolayers down to vm=50m/s for lipid mixtures. No significant attenuation can be detected confirming an adiabatic phenomenon. Finally our data propose a relative lateral density oscillation of \\Delta\\rho/\\rho ~ 2% implying a change in all area dependent physical properties. Order of magnitude estimates from static couplings therefore predict propagating changes in surface potential of 1-50mV, 1 unit in pH (electrochemical potential) and 0.01{\\deg}K in temperature and fall within the same order of magnitude as physical changes measured during nerve pulse propagation. These results therefore strongly support the idea of propagating adiabatic sound waves along nerves as first thoroughly described by Kaufmann in 1989 and recently by Heimburg and Jackson, but claimed by Wilke already in 1912.

J. Griesbauer; A. Wixforth; M. F. Schneider

2010-05-26

116

You Sank My Lipid Rafts!  

ERIC Educational Resources Information Center

The plasma membrane is the membrane that serves as a boundary between the interior of a cell and its extracellular environment. Lipid rafts are microdomains within a cellular membrane that possess decreased fluidity due to the presence of cholesterol, glycolipids, and phospholipids containing longer fatty acids. These domains are involved in many…

Campbell, Tessa N.

2009-01-01

117

Wave Propagation in Lipid Monolayers  

PubMed Central

Abstract Sound waves are excited on lipid monolayers using a set of planar electrodes aligned in parallel with the excitable medium. By measuring the frequency-dependent change in the lateral pressure, we are able to extract the sound velocity for the entire monolayer phase diagram. We demonstrate that this velocity can also be directly derived from the lipid monolayer compressibility, and consequently displays a minimum in the phase transition regime. This minimum decreases from v0 = 170 m/s for one-component lipid monolayers down to vm = 50 m/s for lipid mixtures. No significant attenuation can be detected confirming an adiabatic phenomenon. Finally, our data propose a relative lateral density oscillation of ??/? ?2%, implying a change in all area-dependent physical properties. Order-of-magnitude estimates from static couplings therefore predict propagating changes in surface potential of 1–50 mV, 1 unit in pH (electrochemical potential), and 0.01 K in temperature, and fall within the same order of magnitude as physical changes measured during nerve pulse propagation. These results therefore strongly support the idea of propagating adiabatic sound waves along nerves as first thoroughly described by Kaufmann in 1989 and recently by Heimburg and Jackson, but already claimed by Wilke in 1912. PMID:19917224

Griesbauer, J.; Wixforth, A.; Schneider, M.F.

2009-01-01

118

Diet, Lipids and Brain Development  

Microsoft Academic Search

Brain development is a sequential anatomical process characterised by specific well-defined stages of growth and maturation. One of the fundamental and necessary events in the normal development of the central nervous system in vertebrates is the formation of a myelin sheath. It is becoming more evident that this process is influenced by dietary lipids. A number of findings have indicated

S. Salvati; L. Attorri; C. Avellino; A. Di Biase; M. Sanchez

2000-01-01

119

Original article Lipid utilization and carbohydrate partitioning  

E-print Network

Original article Lipid utilization and carbohydrate partitioning during germination of English — Conversion of reserve lipids in the seed, and carbohydrate and dry matter partitioning dur- ing in lipid content with a concomitant rise in carbohydrates (fig 2); starch appeared to be a transient sink

Paris-Sud XI, Université de

120

Roles of lipid rafts in membrane transport  

Microsoft Academic Search

Cholesterol–sphingolipid microdomains (lipid rafts) are part of the machinery ensuring correct intracellular trafficking of proteins and lipids. The most apparent roles of rafts are in sorting and vesicle formation, although their roles in vesicle movement and cytoskeletal connections as well as in vesicle docking and fusion are coming into focus. New evidence suggests that compositionally distinct lipid microdomains are assembled

Elina Ikonen

2001-01-01

121

Integral hair lipid in human hair follicle  

Microsoft Academic Search

Integral hair lipid (IHL) is bound to the keratinized cell surface to make an environmentally resistant lipid envelope. It is mainly positioned on the hair cuticle and inner root sheath. IHL in the hair follicle may regard as hair barrier to be similar to the epidermal lipid layer functioning as skin barrier. Major constituents of IHL are fatty acid, phytosphingosine,

Won-Soo Lee

2011-01-01

122

Alternative lipid mobilization: The insect shuttle system  

Microsoft Academic Search

Lipid mobilization in long-distance flying insects has revealed a novel concept for lipid transport in the circulatory system during exercise. Similar to energy generation for sustained locomotion in mammals, the work accomplished by non-stop flight activity is powered by oxidation of free fatty acids (FFA) derived from endogenous reserves of triacylglycerol. The transport form of the lipid, however, is diacylglycerol

Dick J. Van der Horst; Dennis Van Hoof; Wil J. A. Van Marrewijk; Kees W. Rodenburg

2002-01-01

123

Lipid stability in meat and meat products  

Microsoft Academic Search

Lipid oxidation is one of the main factors limiting the quality and acceptability of meats and meat products. Oxidative damage to lipids occurs in the living animal because of an imbalance between the production of reactive oxygen species and the animal's defence mechanisms. This may be brought about by a high intake of oxidized lipids or poly-unsaturated fatty acids, or

P. A. Morrissey; P. J. A. Sheehy; K. Galvin; J. P. Kerry; D. J. Buckley

1998-01-01

124

Analysis of lipid rafts in T cells  

Microsoft Academic Search

The plasma membrane of T cells is made of a combination of glycosphingolipids and protein receptors organized in glycolipoprotein microdomains termed lipid rafts. The structural assembly of lipid rafts was investigated by various physical and biochemical assays. Depending on the differentiation status of T cells, the lipid rafts seclude various protein receptors involved in T cell signaling, cytoskeleton reorganization, membrane

Sunil Thomas; Anca Preda-Pais; Sofia Casares; Teodor-D Brumeanu

2004-01-01

125

Lipid rafts in mast cell signaling  

Microsoft Academic Search

Lipid rafts are defined as plasma membrane microdomains enriched with glycosphingolipids and cholesterol which render them insoluble in non-ionic detergents. Many surface receptors are constitutively or inducibly associated with lipid rafts, and it has been suggested that the rafts function as platforms regulating the induction of signaling pathways. The signaling capacity of lipid rafts has been extensively studied in rat

Petr Dráber; Lubica Dráberová

2002-01-01

126

Lipid Raft in Cardiac Health and Disease  

PubMed Central

Lipid rafts are sphingolipid and cholesterol rich micro-domains of the plasma membrane that coordinate and regulate varieties of signaling processes. Lipid rafts are also present in cardiac myocytes and are enriched in signaling molecules and ion channel regulatory proteins. Lipid rafts are receiving increasing attention as cellular organelles contributing to the pathogenesis of several structural and functional processes including cardiac hypertrophy and heart failure. At present, very little is known about the role of lipid rafts in cardiac function and dysfunction. This review will discuss the possible role of lipid rafts in cardiac health and disease. PMID:20436850

Das, Manika; Das, Dipak K

2009-01-01

127

Membrane fusion in vesicles of oligomerizable lipids.  

PubMed Central

Membrane fusion has been examined in a model system of small unilamellar vesicles of synthetic lipids that can be oligomerized through the lipid headgroups. The oligomerization can be induced either in both bilayer leaflets or in the inner leaflet exclusively. Oligomerization leads to denser lipid headgroup packing, with concomitant reduction of lipid lateral diffusion and membrane permeability. As evidenced by lipid mixing assays, electron microscopy, and light scattering, calcium-induced fusion of the bilayer vesicles is strongly retarded and inhibited by oligomerization. Remarkably, oligomerization of only the inner leaflet of the bilayer is already sufficient to affect fusion. The efficiency of inhibition and retardation of fusion critically depend on the relative amount of oligomeric lipid present, on the concentration of calcium ions, and on temperature. Implications for the mechanism of bilayer membrane fusion are discussed in terms of lipid lateral diffusion and membrane curvature effects. PMID:9876149

Ravoo, B J; Weringa, W D; Engberts, J B

1999-01-01

128

[Lipin 1 in lipid metabolism].  

PubMed

The gene encoding lipin 1 was identified with a positional cloning approach that localized the causative mutation in fatty liver dystrophic (fld) mice, a mouse model of lipodystrophy. The fld mouse lacks normal adipose tissue in the body, and displays metabolic dysregulation such as obesity, insulin resistance, and hypertriglyceridemia. Lipin 1 is abundantly expressed in key metabolic tissues, including adipose tissue, skeletal muscle, and liver. In the cytosol, lipin 1 acts as an Mg²?-dependent phosphatidate phosphatase type-1 (PAP1), catalyzing a key step in the synthesis of glycerolipids. In the nucleus, lipin 1 acts as a transcriptional coactivator through its direct interaction with peroxisome proliferator-activated receptor (PPAR) ? coactivator-1? (PGC-1?) and PPAR?. Through two distinct functions in the nucleus and cytosol, lipin 1 modulates lipid metabolism and glucose homeostasis. Here we will discuss recent developments in our understanding of the role of lipin 1 in lipid metabolism. PMID:21804322

Ishimoto, Kenji

2011-01-01

129

Lipid Polymorphisms and Membrane Shape  

PubMed Central

Morphological plasticity of biological membrane is critical for cellular life, as cells need to quickly rearrange their membranes. Yet, these rearrangements are constrained in two ways. First, membrane transformations may not lead to undesirable mixing of, or leakage from, the participating cellular compartments. Second, membrane systems should be metastable at large length scales, ensuring the correct function of the particular organelle and its turnover during cellular division. Lipids, through their ability to exist with many shapes (polymorphism), provide an adequate construction material for cellular membranes. They can self-assemble into shells that are very flexible, albeit hardly stretchable, which allows for their far-reaching morphological and topological behaviors. In this article, we will discuss the importance of lipid polymorphisms in the shaping of membranes and its role in controlling cellular membrane morphology. PMID:21646378

Frolov, Vadim A.; Shnyrova, Anna V.; Zimmerberg, Joshua

2011-01-01

130

Phase Separation in Lipid Membranes  

PubMed Central

Cell membranes show complex behavior, in part because of the large number of different components that interact with each other in different ways. One aspect of this complex behavior is lateral organization of components on a range of spatial scales. We found that lipid-only mixtures can model the range of size scales, from approximately 2 nm up to microns. Furthermore, the size of compositional heterogeneities can be controlled entirely by lipid composition for mixtures such as 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC)/1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC)/cholesterol or sphingomyelin (SM)/DOPC/POPC/cholesterol. In one region of special interest, because of its connection to cell membrane rafts, nanometer-scale domains of liquid-disordered phase and liquid-ordered phase coexist over a wide range of compositions. PMID:21441593

Heberle, Frederick A.; Feigenson, Gerald W.

2011-01-01

131

Anesthetics interacting with lipid rafts.  

PubMed

The exact mechanism by which anesthetics induce cell membrane-mediated modifications is still an open question. Although the fluidization effect of the anesthetic molecules on the cellular membrane is widely recognized, it is not known if anesthetics show any preference for specific membrane domains, namely the lipid rafts. The importance of these membrane micro-domains derives from the fact that they have been associated with cell signaling pathways, as well as with specific drug interactions. The objective of this work is to contribute for the elucidation of this question through the comparison of the anesthetic interactions with membranes of various lipid compositions. Liposomes prepared with an equimolar mixture of POPC, sphingomyelin and cholesterol, were chosen as models for lipid rafts. The interactions of these liposomes with two local anesthetics, tetracaine and lidocaine, and one general anesthetic, propofol, were studied. The effect of cholesterol was investigated by comparing anesthetic interactions with POPC/SM liposomes and POPC/SM/CHOL liposomes. The following experimental techniques were used: quartz crystal microbalance with dissipation, differential scanning calorimetry and phosphorus nuclear magnetic resonance. Although the liposomes investigated by the different techniques are not in the same conditions, it is possible to assemble the information obtained from all experimental techniques employed to reach a general conclusion. Tetracaine interacts more with raftlike domains, lidocaine induces stronger modifications on POPC/SM liposomes and the results for propofol are not fully conclusive but it seems to be the least prone to lipid interactions. The results were compared with those obtained with DMPC-containing liposomes, reported in a previous work. PMID:23142844

Bandeiras, Cátia; Serro, Ana Paula; Luzyanin, Konstantin; Fernandes, Anabela; Saramago, Benilde

2013-01-23

132

Dynamics of multicomponent lipid membranes  

NASA Astrophysics Data System (ADS)

We present theoretical and computational descriptions of the dynamics of multicomponent lipid bilayer membranes. These systems are both model systems for "lipid rafts" in cell membranes and interesting physical examples of quasi-two-dimensional fluids. Our chief tool is a continuum simulation that uses a phase field to track the composition of the membrane, and solves the hydrodynamic equations exactly using the appropriate Green's function (Oseen tensor) for the membrane. We apply this simulation to describe the diffusion of domains in phase-separated membranes, the dynamics of domain flickering, and the process of phase separation in lipid membranes. We then derive an analytical theory to describe domain flickering that is consistent with our simulation results, and use this to analyze experimental measurements of membrane domains. Through this method, we measure the membrane viscosity solely from fluorescence microscopy measurements. We study phase separation in quasi-two-dimensional membranes in depth with both simulations and scaling theory, and classify the different scaling regimes and morphologies, which differ from pure two-dimensional fluids. Our results may explain previous inconsistent measurements of the dynamical scaling exponent for phase separation in membranes. We also extend our theory beyond the simplest model, including the possibility that the membrane will be viscoelastic, as well as considering the inertia of the membrane and the fluid surrounding the membrane.

Camley, Brian Andrew

133

Mechanics of Lipid Bilayer Membranes  

NASA Astrophysics Data System (ADS)

All cells have membranes. The plasma membrane encapsulates the cell's interior, acting as a barrier against the outside world. In cells with nuclei (eukaryotic cells), membranes also form internal compartments (organelles) which carry out specialized tasks, such as protein modification and sorting in the case of the Golgi apparatus, and ATP production in the case of mitochondria. The main components of membranes are lipids and proteins. The proteins can be channels, carriers, receptors, catalysts, signaling molecules, or structural elements, and typically contribute a substantial fraction of the total membrane dry weight. The equilibrium properties of pure lipid membranes are relatively well-understood, and will be the main focus of this article. The framework of elasticity theory and statistical mechanics that we will develop will serve as the foundation for understanding biological phenomena such as the nonequilibrium behavior of membranes laden with ion pumps, the role of membrane elasticity in ion channel gating, and the dynamics of vesicle fission and fusion. Understanding the mechanics of lipid membranes is also important for drug encapsulation and delivery.

Powers, Thomas R.

134

Isolation and analysis of membrane lipids and lipid rafts in common carp (Cyprinus carpio L.).  

PubMed

Cell membranes act as an interface between the interior of the cell and the exterior environment and facilitate a range of essential functions including cell signalling, cell structure, nutrient uptake and protection. It is composed of a lipid bilayer with integrated proteins, and the inner leaflet of the lipid bilayer comprises of liquid ordered (Lo) and liquid disordered (Ld) domains. Lo microdomains, also named as lipid rafts are enriched in cholesterol, sphingomyelin and certain types of proteins, which facilitate cell signalling and nutrient uptake. Lipid rafts have been extensively researched in mammals and the presence of functional lipid rafts was recently demonstrated in goldfish, but there is currently very little knowledge about their composition and function in fish. Therefore a protocol was established for the analysis of lipid rafts and membranous lipids in common carp (Cyprinus carpio L.) tissues. Twelve lipids were identified and analysed in the Ld domain of the membrane with the most predominant lipids found in all tissues being; triglycerides, cholesterol, phosphoethanolamine and phosphatidylcholine. Four lipids were identified in lipid rafts in all tissues analysed, triglycerides (33-62%) always found in the highest concentration followed by cholesterol (24-32%), phosphatidylcholine and sphingomyelin. Isolation of lipid rafts was confirmed by identifying the presence of the lipid raft associated protein flotillin, present at higher concentrations in the detergent resistant fraction. The data provided here build a lipid library of important carp tissues as a baseline for further studies into virus entry, protein trafficking or environmental stress analysis. PMID:24326265

Brogden, Graham; Propsting, Marcus; Adamek, Mikolaj; Naim, Hassan Y; Steinhagen, Dieter

2014-03-01

135

Lipid rafts in neurodegeneration and neuroprotection.  

PubMed

The collective properties of the lipids that form biological membranes give rise to a very high level of lateral organization within the membranes. Lipid-driven membrane organization allows the segregation of membrane-associated components into specific lipid rafts, which function as dynamic platforms for signal transduction, protein processing, and membrane turnover. A number of events essential for the functional integrity of the nervous system occur in lipid rafts and depend on lipid raft organization. Alterations of lipid composition that lead to abnormal lipid raft organization and consequent deregulation of lipid raft-dependent signaling are often associated with neurodegenerative diseases. The amyloidogenic processing of proteins involved in the pathogenesis of major nervous system diseases, including Alzheimer's disease and Parkinson's disease, requires lipid raft-dependent compartmentalization at the membrane level. Improved understanding of the forces that control lipid raft organization will facilitate the development of novel strategies for the effective prevention and treatment of neurodegenerative and age-related brain diseases. PMID:24362851

Sonnino, Sandro; Aureli, Massimo; Grassi, Sara; Mauri, Laura; Prioni, Simona; Prinetti, Alessandro

2014-08-01

136

Lipid converter, a framework for lipid manipulations in molecular dynamics simulations.  

PubMed

Construction of lipid membrane and membrane protein systems for molecular dynamics simulations can be a challenging process. In addition, there are few available tools to extend existing studies by repeating simulations using other force fields and lipid compositions. To facilitate this, we introduce Lipid Converter, a modular Python framework for exchanging force fields and lipid composition in coordinate files obtained from simulations. Force fields and lipids are specified by simple text files, making it easy to introduce support for additional force fields and lipids. The converter produces simulation input files that can be used for structural relaxation of the new membranes. PMID:25081234

Larsson, Per; Kasson, Peter M

2014-11-01

137

Lipid phase control of DNA delivery  

SciTech Connect

Cationic lipids form nanoscale complexes (lipoplexes) with polyanionic DNA and can be utilized to deliver DNA to cells for transfection. Here we report the correlation between delivery efficiency of these DNA carriers and the mesomorphic phases they form when interacting with anionic membrane lipids. Specifically, formulations that are particularly effective DNA carriers form phases of highest negative interfacial curvature when mixed with anionic lipids, whereas less effective formulations form phases of lower curvature. Structural evolution of the carrier lipid/DNA complexes upon interaction with cellular lipids is hence suggested as a controlling factor in lipid-mediated DNA delivery. A strategy for optimizing lipofection is deduced. The behavior of a highly effective lipoplex formulation, DOTAP/DOPE, is found to conform to this 'efficiency formula'.

Koynova, Rumiana; Wang, Li; Tarahovsky, Yury; MacDonald, Robert C. (NWU)

2010-01-18

138

Droplet Microfluidics for Artificial Lipid Bilayers  

NASA Astrophysics Data System (ADS)

Droplet interface bilayer is a versatile approach that allows formation of artificial lipid bilayer membrane at the interface of two lipid monolayer coated aqueous droplets in a lipid filled oil medium. Versatility exists in the form of voltage control of DIB area, ability of forming networks of DIBs, volume control of droplets and lipid-oil, and ease of reformation. Significant effect of voltage on the area and capacitance of DIB as well as DIB networks are characterized using simultaneous optical and electrical recordings. Mechanisms behind voltage-induced effects on DIBs are investigated. Photo induced effect on the DIB membrane porosity is obtained by incorporating UVC-sensitive photo-polymerizable lipids in DIB. Photo-induced effects can be extended for in-vitro studies of triggered release of encapsulated contents across membranes. A droplet based low voltage digital microfluidic platform is developed to automate DIB formation, which could potentially be used for forming arrays of lipid bilayer membranes.

Punnamaraju, Srikoundinya; Steckl, Andrew

2012-02-01

139

Phase diagrams and lipid domains in multicomponent lipid bilayer mixtures  

PubMed Central

Understanding the phase behavior of biological membranes is helped by the study of more simple systems. Model membranes that have as few as 3 components exhibit complex phase behavior that can be well described, providing insight for biological membranes. A number of different studies are in agreement on general findings for some compositional phase diagrams, in particular, those that model the outer leaflet of animal cell plasma membranes. These model mixtures include cholesterol, together with one high-melting lipid and one low-melting lipid. An interesting finding is of two categories of such 3-component mixtures, leading to what we term Type I and Type II compositional phase diagrams. The latter have phase regions of macroscopic coexisting domains of {L?+L?+Lo} and of {L?+Lo}, with domains resolved under the light microscope. Type I mixtures have the same phase coexistence regions, but the domains seem to be nanoscopic. Type I mixtures are likely to be better models for biological membranes. PMID:18805392

Feigenson, Gerald W.

2009-01-01

140

Polar lipid composition of a new halobacterium  

NASA Technical Reports Server (NTRS)

Investigations of the polar lipid composition of a new aerobic, extremely halophilic aracheabacterium capable of nitrate reduction have shown that this organism contains two previously unknown phospholycolipids derived from diphytanyl glycerol diethers. Comparison of the lipid pattern from this new isolate with other known strains indicate that this organism is novel. On the basis of the unique polar lipid pattern it can be concluded that this organism represents a new taxon, at least at the species level.

Tindall, B. J.; Tomlinson, G. A.; Hochstein, L. I.

1987-01-01

141

Regional lipid composition in the rat brain  

Microsoft Academic Search

The lipid composition of the brain is of great importance to its metabolism and function. Although much research has been\\u000a done on regional brain lipid composition, studies usually suffer from limited brain regions or from limited lipids analyzed.\\u000a We modified a previously described method for the separation of brain phospholipids and glycolipids, improving the separation\\u000a and sensitivity of the method.

Mikulas Chavko; Edwin M. Nemoto; John A. Melick

1993-01-01

142

Lipid composition of oats ( Avena sativa L.)  

Microsoft Academic Search

Compositions of lipids extracted from a sample of Hinoat oat by seven solvent systems and that extracted with chloroform\\/methanol\\u000a (2:1 v\\/v) from six selected cultivars representing high and low lipid contents are reported. Lipid components (steryl esters,\\u000a triglycerides, partial glycerides, free fatty acids, glycolipids and phospholipids) were separated by silicic acid column\\u000a chromatography and thin layer chromatography and quantitated by

M. R. Sahasrabudhe

1979-01-01

143

Bactericidal Activities of Milk Lipids  

PubMed Central

The bactericidal capacity of digestion products of bovine milk triglycerides and membrane lipids was tested in vitro using Escherichia coli O157:H7, Salmonella enteritidis, Campylobacter jejuni, Listeria monocytogenes, and Clostridium perfringens. C10:0 and C12:0 fatty acids and digestion products of sphingolipids appeared to be effective bactericidal agents, whereas digestion products of phosphoglycerides were moderately bactericidal. Thus, milk fat sphingolipids and triglycerides, particularly those containing C10:0 and C12:0 fatty acids, may protect against food-borne gastroenteritis. PMID:11257052

Sprong, R. Corinne; Hulstein, Marco F. E.; Van der Meer, Roelof

2001-01-01

144

Cholesterol Perturbs Lipid Bilayers Nonuniversally  

SciTech Connect

Cholesterol is well known to modulate the physical properties of biomembranes. Using modern x-ray scattering methods, we have studied the effects of cholesterol on the bending modulus K{sub C}, the thickness D{sub HH}, and the orientational order parameter S{sub xray} of lipid bilayers. We find that the effects are different for at least three classes of phospholipids characterized by different numbers of saturated hydrocarbon chains. Most strikingly, cholesterol strongly increases K{sub C} when both chains of the phospholipid are fully saturated but not at all when there are two monounsaturated chains.

Pan Jianjun; Mills, Thalia T.; Tristram-Nagle, Stephanie; Nagle, John F. [Physics Department, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States)

2008-05-16

145

Phosphoinositides alter lipid bilayer properties  

PubMed Central

Phosphatidylinositol-4,5-bisphosphate (PIP2), which constitutes ?1% of the plasma membrane phospholipid, plays a key role in membrane-delimited signaling. PIP2 regulates structurally and functionally diverse membrane proteins, including voltage- and ligand-gated ion channels, inwardly rectifying ion channels, transporters, and receptors. In some cases, the regulation is known to involve specific lipid–protein interactions, but the mechanisms by which PIP2 regulates many of its various targets remain to be fully elucidated. Because many PIP2 targets are membrane-spanning proteins, we explored whether the phosphoinositides might alter bilayer physical properties such as curvature and elasticity, which would alter the equilibrium between membrane protein conformational states—and thereby protein function. Taking advantage of the gramicidin A (gA) channels’ sensitivity to changes in lipid bilayer properties, we used gA-based fluorescence quenching and single-channel assays to examine the effects of long-chain PIP2s (brain PIP2, which is predominantly 1-stearyl-2-arachidonyl-PIP2, and dioleoyl-PIP2) on bilayer properties. When premixed with dioleoyl-phosphocholine at 2 mol %, both long-chain PIP2s produced similar changes in gA channel function (bilayer properties); when applied through the aqueous solution, however, brain PIP2 was a more potent modifier than dioleoyl-PIP2. Given the widespread use of short-chain dioctanoyl-phosphoinositides, we also examined the effects of diC8-phosphoinositol (PI), PI(4,5)P2, PI(3,5)P2, PI(3,4)P2, and PI(3,4,5)P3. The diC8 phosphoinositides, except for PI(3,5)P2, altered bilayer properties with potencies that decreased with increasing head group charge. Nonphosphoinositide diC8 phospholipids generally were more potent bilayer modifiers than the polyphosphoinositides. These results show that physiological increases or decreases in plasma membrane PIP2 levels, as a result of activation of PI kinases or phosphatases, are likely to alter lipid bilayer properties, in addition to any other effects they may have. The results further show that exogenous PIP2, as well as structural analogues that differ in acyl chain length or phosphorylation state, alters lipid bilayer properties at the concentrations used in many cell physiological experiments. PMID:23712549

Hobart, E. Ashley; Koeppe, Roger E.; Andersen, Olaf S.

2013-01-01

146

SEASONAL VARIABILTIY LIPIDS, LIPID CLASSES AND PCBS IN INDIGENOUS POPULATIONS OF RIBBED MUSSELS, MODIOLUS DEMISSUS  

EPA Science Inventory

Two indigenous ribbed mussel (Modiolus demissus) populations were sampled approximately every four weeks during 1997 to investigate the seasonal variability of total lipids, lipid classes, and polychlorinated biphenyl (PCB) concentrations. One population was located in a highly c...

147

Lipids of Venezuelan Equine Encephalomyelitis Virus and Their Relationship to the Lipids of the Host.  

National Technical Information Service (NTIS)

Venezuelan equine encephalomyelitis (VEE) virus derived from chick embryo and chick fibroblast (CF) cells was comprehensively analyzed for fatty acids, phospholipids and neutral lipids, to determine whether differences in the lipid composition of the viru...

F. P. Heydrick, R. F. Wachter, E. H. Ludwig

1968-01-01

148

Dialysis for Intoxication with Lipid Soluble Drugs: Enhancement of Glutethimide Extraction with Lipid Dialysate.  

National Technical Information Service (NTIS)

These in vivo studies demonstrate that the removal of glutethimide during dialysis is significantly increased when lipid is substituted for the usual aqueous dialysis solution. The very low water solubility of many lipid soluble compounds probably limits ...

J. H. Shinaberger, L. Shear, L. E. Clayton, K. G. Barry, M. Knowlton

1965-01-01

149

Polar lipid composition of mammalian hair.  

PubMed

The types and amounts of polar lipids from the hair of monkey (Macacca fascicularis), dog (Canis familiaris), pig (Sus scrofa) and porcupine (Erethizon dorsatum) have been determined by quantitative thin-layer chromatography. The polar lipid content of the hair samples ranged from 0.6 to 1.6 wt%. Lipid compositions included ceramides (57-63% of the polar lipid by weight), glycosphingolipids (7-9%) and cholesteryl sulfate (22-29%). Several minor components (4-7%) remain unidentified. The results suggest that cholesteryl sulfate may be an important determinant of the cohesiveness of hair. PMID:3581794

Wix, M A; Wertz, P W; Downing, D T

1987-01-01

150

Steroidal compounds in commercial parenteral lipid emulsions.  

PubMed

Parenteral nutrition lipid emulsions made from various plant oils contain steroidal compounds, called phytosterols. During parenteral administration of lipid emulsions, phytosterols can reach levels in the blood that are many fold higher than during enteral administration. The elevated phytosterol levels have been associated with the development of liver dysfunction and the rare development of liver failure. There is limited information available in the literature related to phytosterol concentrations in lipid emulsions. The objective of the current study was to validate an assay for steroidal compounds found in lipid emulsions and to compare their concentrations in the most commonly used parenteral nutrition lipid emulsions: Liposyn(®) II, Liposyn(®) III, Lipofundin(®) MCT, Lipofundin(®) N, Structolipid(®), Intralipid(®), Ivelip(®) and ClinOleic(®). Our data demonstrates that concentrations of the various steroidal compounds varied greatly between the eight lipid emulsions, with the olive oil-based lipid emulsion containing the lowest levels of phytosterols and cholesterol, and the highest concentration of squalene. The clinical impression of greater incidences of liver dysfunction with soybean versus MCT/LCT and olive/soy lipid emulsions may be reflective of the levels of phytosterols in these emulsions. This information may help guide future studies and clinical care of patients with lipid emulsion-associated liver dysfunction. PMID:23016123

Xu, Zhidong; Harvey, Kevin A; Pavlina, Thomas; Dutot, Guy; Hise, Mary; Zaloga, Gary P; Siddiqui, Rafat A

2012-08-01

151

Supported Lipid Bilayer/Carbon Nanotube Hybrids  

NASA Astrophysics Data System (ADS)

We form supported lipid bilayers on single-walled carbon nanotubes and use this hybrid structure to probe the properties of lipid membranes and their functional constituents. We first demonstrate membrane continuity and lipid diffusion over the nanotube. A membrane-bound tetanus toxin protein, on the other hand, sees the nanotube as a diffusion barrier whose strength depends on the diameter of the nanotube. Finally, we present results on the electrical detection of specific binding of streptavidin to biotinylated lipids with nanotube field effect transistors. Possible techniques to extract dynamic information about the protein binding events will also be discussed.

Zhou, Xinjian; Moran-Mirabal, Jose; Craighead, Harold; McEuen, Paul

2007-03-01

152

A Simulation Study on Multicomponent Lipid Bilayer  

E-print Network

Simulation of a multicomponent lipid bilayer having a fixed percentage of cholesterol is done to study phase transition leading to domain formation. The concept of random lattice has been used in simulation to account for the coupling between the internal and translational degrees of freedom of lipid molecules. Considering a canonical ensemble, dissimilar lipid molecules are allowed to exchange their positions in the lattice subject to standard metropolis algorithm. The steps involved in the process effectively takes into account for the movement of sphingolipids and cholesterol molecules helping formation of cholesterol rich domains of saturated lipids as found in natural membranes.

Srilekha Banerjee; Jayashree Saha

2005-05-05

153

The challenge of lipid rafts Linda J. Pike1  

E-print Network

The challenge of lipid rafts Linda J. Pike1 Washington University School of Medicine Department to as lipid rafts. This review sum- marizes current thinking on the nature of lipid rafts focusing on the role of these membrane do- mains.--Pike, L. J. The challenge of lipid rafts. J. Lipid Res. 2009. S323­S328. Supplementary

Pike, Linda J.

154

T cell adhesion regulation from clustering GM1 lipid rafts  

Microsoft Academic Search

Lipid rafts are small laterally mobile cell membrane structures that are highly enriched in lymphocyte signaling molecules. Lipid rafts can form from the assembly of specialized lipids and proteins through hydrophobic associations from saturated acyl chains. GM1 gangliosides are a common lipid raft component and have been shown to be essential in many T cell functions. Current lipid raft theory

Jason Sterling Mitchell

2006-01-01

155

Chemistry and Physics of Lipids 143 (2006) 110 Partial molecular volumes of lipids and cholesterol  

E-print Network

Chemistry and Physics of Lipids 143 (2006) 1­10 Partial molecular volumes of lipids and cholesterol Available online 28 April 2006 Abstract Volumetric measurements are reported for fully hydrated lipid/cholesterol for mole fractions of cholesterol x from 0 to 0.5. Unlike previous cholesterol mixture studies, we

Nagle, John F.

156

Liquid immiscibility in model bilayer lipid membranes  

NASA Astrophysics Data System (ADS)

There is growing evidence that cell plasma membranes are laterally organized into "raft" regions in which particular lipids and proteins are concentrated. These domains have sub-micron dimensions and have been implicated in vital cell functions. Similar liquid domains are observed in model bilayer membrane mixtures that mimick cellular lipid compositions. In model membranes, domains can be large (microns) and can readily form in the absence of proteins. This thesis presents studies of liquid immiscibility in model membrane systems using two experimental methods. By fluorescence microscopy, this thesis documents that miscibility transitions occur in a wide variety of ternary lipid mixtures containing high melting temperature (saturated) lipids, low melting temperature (usually unsaturated) lipids, and cholesterol. I have constructed detailed miscibility phase diagrams for three separate ternary lipid mixtures (DOPC/DPPC/Chol, DOPC/PSM/Chol, and POPC/PSM/Chol). Phase separation is also observed in membranes of lipids extracted from human erythrocytes. NMR experiments probe lipid order and verify the coexistence of a saturated lipid and cholesterol rich liquid ordered (Lo) phase with a more disordered, unsaturated lipid rich liquid crystalline (Lalpha) phase at low temperatures. These experiments also find multiple thermodynamic transitions and lipid organization on different length-scales. This complexity is revealed because fluorescence microscopy and NMR probe lipid order at different length-scales (>1mum vs. ˜100nm). NMR detects small domains (˜80nm) at temperatures just below the miscibility transition, even though micron-scale domains are observed by fluorescent microscopy. NMR does detect large-scale ("100nm) demixing, but at a lower temperature. In addition, it has long been known that >10nm length-scale structure is present in many lipid mixtures containing cholesterol and at least one additional lipid species, though it is shown here that only a subset of these mixtures exhibit large-scale phase separation when observed by fluorescence microscopy or NMR. The results of many experimental studies are compiled and several possible models for underlying phase diagrams are discussed. The interplay of small and large scale order in cholesterol containing membranes has provided insight into how the miscibility transition relates to lipid rafts in biological membranes.

Veatch, Sarah L.

157

Morphological Changes Associated with Lipid Mobilization  

Microsoft Academic Search

Morphological changes associated with mobilization of lipid were studied in epididymal adipose tissue from fasted and from alloxan diabetic rats. In both groups of animals a decrease in lipid content was accompanied by the formation of complex frond-like cyto- plasmic processes and of loops and folds of basement membrane which extended from cell surfaces. These changes, evident after 1 day

JOSEPH R. WILLIAMSON

158

Lipid extraction from isolated single nerve cells  

NASA Technical Reports Server (NTRS)

A method of extracting lipids from single neurons isolated from lyophilized tissue is described. The method permits the simultaneous extraction of lipids from 30-40 nerve cells and for each cell provides equal conditions of solvent removal at the conclusion of extraction.

Krasnov, I. V.

1977-01-01

159

Modeling of cationic lipid-DNA complexes.  

PubMed

Cationic lipid-DNA complexes, often referred to as lipoplexes, are formed spontaneously in aqueous solutions upon mixing DNA and liposomes composed of cationic and nonionic lipids. Understanding the mechanisms underlying lipoplex formation, structure and phase behavior is crucial for their further development and design as non-viral transfection vectors in gene therapy. From a physical point of view, lipoplexes are ordered, self-assembled, composite aggregates. Their preferred spatial geometry and phase behavior are governed by a delicate coupling between the electrostatic interactions which drive lipoplex formation and the elastic properties of the constituent lipid layers, both depending on the molecular nature and composition of the lipid mixture. In this review we outline some recent efforts to model the microscopic structure, energetic and phase behavior of cationic lipid-DNA mixtures, focusing on the two principal aggregation geometries: the lamellar (L(alpha)(C)), or "sandwich" complexes, and the hexagonal (H(II)(C)), or "honeycomb" complexes. We relate the structural and thermodynamic properties of these two "canonical" lipoplex morphologies to their appearance in phase diagrams of DNA-lipid mixtures, emphasizing the crucial role fulfilled by the molecular packing characteristics of the cationic and neutral lipids, as reflected in the curvature elastic properties of the mixed lipid layer. PMID:14754414

May, S; Ben-Shaul, A

2004-01-01

160

Sub-wavelength infrared imaging of lipids  

PubMed Central

Infrared absorption spectroscopy of lipid layers was performed by combining optics and scanning probe microscopy. This experimental approach enables sub-diffraction IR imaging with a spatial resolution on the nanometer scale of 1, 2-dioleoyl-sn-glycero-3-phosphocholine lipid layers. PMID:21326633

Yarrow, Fiona; Kennedy, Eamonn; Salaun, Frederic

2011-01-01

161

Intravenous lipid emulsion in clinical toxicology  

PubMed Central

Intravenous lipid emulsion is an established, effective treatment for local anesthetic-induced cardiovascular collapse. The predominant theory for its mechanism of action is that by creating an expanded, intravascular lipid phase, equilibria are established that drive the offending drug from target tissues into the newly formed 'lipid sink'. Based on this hypothesis, lipid emulsion has been considered a candidate for generic reversal of toxicity caused by overdose of any lipophilic drug. Recent case reports of successful resuscitation suggest the efficacy of lipid emulsion infusion for treating non-local anesthetic overdoses across a wide spectrum of drugs: beta blockers, calcium channel blockers, parasiticides, herbicides and several varieties of psychotropic agents. Lipid emulsion therapy is gaining acceptance in emergency rooms and other critical care settings as a possible treatment for lipophilic drug toxicity. While protocols exist for administration of lipid emulsion in the setting of local anesthetic toxicity, no optimal regimen has been established for treatment of acute non-local anesthetic poisonings. Future studies will shape the evolving recommendations for lipid emulsion in the setting of non-local anesthetic drug overdose. PMID:20923546

2010-01-01

162

21 CFR 862.1470 - Lipid (total) test system.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Lipid (total) test system. 862.1470 Section...Clinical Chemistry Test Systems § 862.1470 Lipid (total) test system. (a) Identification. A lipid (total) test system is a device...

2013-04-01

163

Method of fabricating lipid bilayer membranes on solid supports  

NASA Technical Reports Server (NTRS)

The present invention provides a method of producing a planar lipid bilayer on a solid support. With this method, a solution of lipid vesicles is first deposited on the solid support. Next, the lipid vesicles are destabilized by adding an amphipathic peptide solution to the lipid vesicle solution. This destabilization leads to production of a planar lipid bilayer on the solid support. The present invention also provides a supported planar lipid bilayer, where the planar lipid bilayer is made of naturally occurring lipids and the solid support is made of unmodified gold or titanium oxide. Preferably, the supported planar lipid bilayer is continuous. The planar lipid bilayer may be made of any naturally occurring lipid or mixture of lipids, including, but not limited to phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidylinsitol, cardiolipin, cholesterol, and sphingomyelin.

Cho, Nam-Joon (Inventor); Frank, Curtis W. (Inventor); Glenn, Jeffrey S. (Inventor); Cheong, Kwang Ho (Inventor)

2012-01-01

164

Model Answers to Lipid Membrane Questions  

PubMed Central

Ever since it was discovered that biological membranes have a core of a bimolecular sheet of lipid molecules, lipid bilayers have been a model laboratory for investigating physicochemical and functional properties of biological membranes. Experimental and theoretical models help the experimental scientist to plan experiments and interpret data. Theoretical models are the theoretical scientist’s preferred toys to make contact between membrane theory and experiments. Most importantly, models serve to shape our intuition about which membrane questions are the more fundamental and relevant ones to pursue. Here we review some membrane models for lipid self-assembly, monolayers, bilayers, liposomes, and lipid–protein interactions and illustrate how such models can help answering questions in modern lipid cell biology. PMID:21610116

Mouritsen, Ole G.

2011-01-01

165

Diffusion in low-dimensional lipid membranes.  

PubMed

The diffusion behavior of biological components in cellular membranes is vital to the function of cells. By collapsing the complexity of planar 2D membranes down to one dimension, fundamental investigations of bimolecular behavior become possible in one dimension. Here we develop lipid nanolithography methods to produce membranes, under fluid, with widths as low as 6 nm but extending to microns in length. We find reduced lipid mobility, as the width is reduced below 50 nm, suggesting different lipid packing in the vicinity of boundaries. The insertion of a membrane protein, M2, into these systems, allowed characterization of protein diffusion using high-speed AFM to demonstrate the first membrane protein 1D random walk. These quasi-1D lipid bilayers are ideal for testing and understanding fundamental concepts about the roles of dimensionality and size on physical properties of membranes from energy transfer to lipid packing. PMID:25166509

Heath, George R; Roth, Johannes; Connell, Simon D; Evans, Stephen D

2014-10-01

166

Lipid compartmentalization in the endosome system.  

PubMed

Lipids play an essential role in the structure of the endosomal membranes as well as in their dynamic rearrangement during the transport of internalized cargoes along the endocytic pathway. In this review, we discuss the function of endosomal lipids mainly in mammalian cells, focusing on two well-known components of the lipid rafts, sphingomyelin and cholesterol, as well as on three anionic phospholipids, phosphatidylserine, polyphosphoinositides and the atypical phospholipid, bis(monoacylglycero)phosphate/lysobisphosphatidic acid. We detail the structure, metabolism, distribution and role of these lipids in the endosome system as well as their importance in pathological conditions where modification of the endosomal membrane flow can lead to various diseases such as lipid-storage diseases, myopathies and neuropathies. PMID:24747366

Hullin-Matsuda, Françoise; Taguchi, Tomohiko; Greimel, Peter; Kobayashi, Toshihide

2014-07-01

167

Lxr-driven enterocyte lipid droplet formation delays transport of ingested lipids.  

PubMed

Liver X receptors (Lxrs) are master regulators of cholesterol catabolism, driving the elimination of cholesterol from the periphery to the lumen of the intestine. Development of pharmacological agents to activate Lxrs has been hindered by synthetic Lxr agonists' induction of hepatic lipogenesis and hypertriglyceridemia. Elucidating the function of Lxrs in regulating enterocyte lipid handling might identify novel aspects of lipid metabolism that are pharmacologically amenable. We took a genetic approach centered on the single Lxr gene nr1h3 in zebrafish to study the role of Lxr in enterocyte lipid metabolism. Loss of nr1h3 function causes anticipated gene regulatory changes and cholesterol intolerance, collectively reflecting high evolutionary conservation of zebrafish Lxra function. Intestinal nr1h3 activation delays transport of absorbed neutral lipids, with accumulation of neutral lipids in enterocyte cytoplasmic droplets. This delay in transport of ingested neutral lipids protects animals from hypercholesterolemia and hepatic steatosis induced by a high-fat diet. On a gene regulatory level, Lxra induces expression of acsl3a, which encodes acyl-CoA synthetase long-chain family member 3a, a lipid droplet-anchored protein that directs fatty acyl chains into lipids. Forced overexpression of acls3a in enterocytes delays, in part, the appearance of neutral lipids in the vasculature of zebrafish larvae. Activation of Lxr in the intestine cell-autonomously regulates the rate of delivery of absorbed lipids by inducting a temporary lipid intestinal droplet storage depot. PMID:25030662

Cruz-Garcia, Lourdes; Schlegel, Amnon

2014-09-01

168

?-Synuclein Senses Lipid Packing Defects and Induces Lateral Expansion of Lipids Leading to Membrane Remodeling*  

PubMed Central

There is increasing evidence for the involvement of lipid membranes in both the functional and pathological properties of ?-synuclein (?-Syn). Despite many investigations to characterize the binding of ?-Syn to membranes, there is still a lack of understanding of the binding mode linking the properties of lipid membranes to ?-Syn insertion into these dynamic structures. Using a combination of an optical biosensing technique and in situ atomic force microscopy, we show that the binding strength of ?-Syn is related to the specificity of the lipid environment (the lipid chemistry and steric properties within a bilayer structure) and to the ability of the membranes to accommodate and remodel upon the interaction of ?-Syn with lipid membranes. We show that this interaction results in the insertion of ?-Syn into the region of the headgroups, inducing a lateral expansion of lipid molecules that can progress to further bilayer remodeling, such as membrane thinning and expansion of lipids out of the membrane plane. We provide new insights into the affinity of ?-Syn for lipid packing defects found in vesicles of high curvature and in planar membranes with cone-shaped lipids and suggest a comprehensive model of the interaction between ?-Syn and lipid bilayers. The ability of ?-Syn to sense lipid packing defects and to remodel membrane structure supports its proposed role in vesicle trafficking. PMID:23740253

Ouberai, Myriam M.; Wang, Juan; Swann, Marcus J.; Galvagnion, Celine; Guilliams, Tim; Dobson, Christopher M.; Welland, Mark E.

2013-01-01

169

Effect of extrusion pressure and lipid properties on the size and polydispersity of lipid vesicles.  

PubMed Central

The production of vesicles, spherical shells formed from lipid bilayers, is an important aspect of their recent application to drug delivery technologies. One popular production method involves pushing a lipid suspension through cylindrical pores in polycarbonate membranes. However, the actual mechanism by which the polydisperse, multilamellar lipid suspension breaks up into a relatively monodisperse population of vesicles is not well understood. To learn about factors influencing this process, we have characterized vesicles produced under different extrusion parameters and from different lipids. We find that extruded vesicles are only produced above a certain threshold extrusion pressure and have sizes that depend on the extrusion pressure. The minimum pressure appears to be associated with the lysis tension of the lipid bilayer rather than any bending modulus of the system. The flow rate of equal concentration lipid solutions through the pores, after being corrected for the viscosity of water, is independent of lipid properties. PMID:9635753

Hunter, D G; Frisken, B J

1998-01-01

170

Lipid-engineered Escherichia coli Membranes Reveal Critical Lipid Headgroup Size for Protein Function*  

PubMed Central

Escherichia coli membranes have a substantial bilayer curvature stress due to a large fraction of the nonbilayer-prone lipid phosphatidylethanolamine, and a mutant (AD93) lacking this lipid is severely crippled in several membrane-associated processes. Introduction of four lipid glycosyltransferases from Acholeplasma laidlawii and Arabidopsis thaliana, synthesizing large amounts of two nonbilayer-prone, and two bilayer-forming gluco- and galacto-lipids, (i) restored the curvature stress with the two nonbilayer lipids, and (ii) diluted the high negative lipid surface charge in all AD93 bilayers. Surprisingly, the bilayer-forming diglucosyl-diacylglycerol was almost as good in improving AD93 membrane processes as the two nonbilayer-prone glucosyl-diacylglycerol and galactosyl-diacylglycerol lipids, strongly suggesting that lipid surface charge dilution by these neutral lipids is very important for E. coli. Increased acyl chain length and unsaturation, plus cardiolipin (nonbilayer-prone) content, were probably also beneficial in the modified strains. However, despite a correct transmembrane topology for the transporter LacY in the diglucosyl-diacylglycerol clone, active transport failed in the absence of a nonbilayer-prone glycolipid. The corresponding digalactosyl-diacylglycerol bilayer lipid did not restore AD93 membrane processes, despite analogous acyl chain and cardiolipin contents. Chain ordering, probed by bis-pyrene lipids, was substantially lower in the digalactosyl-diacylglycerol strain lipids due to its extended headgroup. Hence, a low surface charge density of anionic lipids is important in E. coli membranes, but is inefficient if the headgroup of the diluting lipid is too large. This strongly indicates that a certain magnitude of the curvature stress is crucial for the bilayer in vivo. PMID:18981182

Wikstrom, Malin; Kelly, Amelie A.; Georgiev, Alexander; Eriksson, Hanna M.; Klement, Maria Rosen; Bogdanov, Mikhail; Dowhan, William; Wieslander, Ake

2009-01-01

171

Influence of protein and lipid domains on the structure, fluidity and phase behavior of lipid bilayer membranes  

E-print Network

The lipid bilayer forms the basic structure of the cell membrane, which is a heterogeneous matrix of proteins and lipids that provides a barrier between the interior of a cell and its outside environment. Protein and lipid ...

Horton, Margaret R. (Margaret Ruth)

2007-01-01

172

DNA release from lipoplexes by anionic lipids: correlation with lipid mesomorphism, interfacial curvature, and membrane fusion  

SciTech Connect

DNA release from lipoplexes is an essential step during lipofection and is probably a result of charge neutralization by cellular anionic lipids. As a model system to test this possibility, fluorescence resonance energy transfer between DNA and lipid covalently labeled with Cy3 and BODIPY, respectively, was used to monitor the release of DNA from lipid surfaces induced by anionic liposomes. The separation of DNA from lipid measured this way was considerably slower and less complete than that estimated with noncovalently labeled DNA, and depends on the lipid composition of both lipoplexes and anionic liposomes. This result was confirmed by centrifugal separation of released DNA and lipid. X-ray diffraction revealed a clear correlation of the DNA release capacity of the anionic lipids with the interfacial curvature of the mesomorphic structures developed when the anionic and cationic liposomes were mixed. DNA release also correlated with the rate of fusion of anionic liposomes with lipoplexes. It is concluded that the tendency to fuse and the phase preference of the mixed lipid membranes are key factors for the rate and extent of DNA release. The approach presented emphasizes the importance of the lipid composition of both lipoplexes and target membranes and suggests optimal transfection may be obtained by tailoring lipoplex composition to the lipid composition of target cells.

Tarahovsky, Yury S.; Koynova, Rumiana; MacDonald, Robert C. (Northwestern)

2010-01-18

173

Actively maintained lipid nanodomains in biomembranes  

NASA Astrophysics Data System (ADS)

Lipid rafts, defined as domains rich in cholesterol and sphingolipids, are involved in many important plasma membrane functions. Recent studies suggest that the way cells handle membrane cholesterol is fundamental in the formation of such lateral heterogeneities. We propose to model the plasma membrane as a nonequilibrium phase-separating system where cholesterol is dynamically incorporated and released. The model shows how cellular regulation of membrane cholesterol may determine the nanoscale lipid organization when the lipid mixture is close to a phase separation boundary, providing a plausible mechanism for raft formation in vivo.

Gómez, Jordi; Sagués, Francesc; Reigada, Ramon

2008-02-01

174

High-throughput formation of lipid bilayer membrane arrays with an asymmetric lipid composition.  

PubMed

We present a micro-device in which more than 10,000 asymmetric lipid bilayer membranes are formed at a time on micro-chamber arrays. The arrayed asymmetric lipid bilayers, where lipid compositions are different between the inner and outer leaflets, are formed with high efficiency of over 97% by injecting several types of liquids into a micro-device that has hydrophilic-in-hydrophobic surfaces. The lipid compositional asymmetry is an intrinsic property of bio-membranes, and therefore, this micro-device extends the versatility of artificial lipid-bilayer systems, which were previously limited to symmetric bilayer formation, and could contribute to the understanding of the role of lipid compositional asymmetry in cell physiology and also to further analytical and pharmacological applications. PMID:25399694

Watanabe, Rikiya; Soga, Naoki; Yamanaka, Tomoko; Noji, Hiroyuki

2014-01-01

175

Update of the LIPID MAPS comprehensive classification system for lipids1  

PubMed Central

In 2005, the International Lipid Classification and Nomenclature Committee under the sponsorship of the LIPID MAPS Consortium developed and established a “Comprehensive Classification System for Lipids” based on well-defined chemical and biochemical principles and using an ontology that is extensible, flexible, and scalable. This classification system, which is compatible with contemporary databasing and informatics needs, has now been accepted internationally and widely adopted. In response to considerable attention and requests from lipid researchers from around the globe and in a variety of fields, the comprehensive classification system has undergone significant revisions over the last few years to more fully represent lipid structures from a wider variety of sources and to provide additional levels of detail as necessary. The details of this classification system are reviewed and updated and are presented here, along with revisions to its suggested nomenclature and structure-drawing recommendations for lipids. PMID:19098281

Fahy, Eoin; Subramaniam, Shankar; Murphy, Robert C.; Nishijima, Masahiro; Raetz, Christian R. H.; Shimizu, Takao; Spener, Friedrich; van Meer, Gerrit; Wakelam, Michael J. O.; Dennis, Edward A.

2009-01-01

176

High-throughput formation of lipid bilayer membrane arrays with an asymmetric lipid composition  

PubMed Central

We present a micro-device in which more than 10,000 asymmetric lipid bilayer membranes are formed at a time on micro-chamber arrays. The arrayed asymmetric lipid bilayers, where lipid compositions are different between the inner and outer leaflets, are formed with high efficiency of over 97% by injecting several types of liquids into a micro-device that has hydrophilic-in-hydrophobic surfaces. The lipid compositional asymmetry is an intrinsic property of bio-membranes, and therefore, this micro-device extends the versatility of artificial lipid-bilayer systems, which were previously limited to symmetric bilayer formation, and could contribute to the understanding of the role of lipid compositional asymmetry in cell physiology and also to further analytical and pharmacological applications. PMID:25399694

Watanabe, Rikiya; Soga, Naoki; Yamanaka, Tomoko; Noji, Hiroyuki

2014-01-01

177

Hypersaline Microbial Mat Lipid Biomarkers  

NASA Technical Reports Server (NTRS)

Lipid biomarkers and compound specific isotopic abundances are powerful tools for studies of contemporary microbial ecosystems. Knowledge of the relationship of biomarkers to microbial physiology and community structure creates important links for understanding the nature of early organisms and paleoenvironments. Our recent work has focused on the hypersaline microbial mats in evaporation ponds at Guerrero Negro, Baja California Sur, Mexico. Specific biomarkers for diatoms, cyanobacteria, archaea, green nonsulfur (GNS), sulfate reducing, sulfur oxidizing and methanotrophic bacteria have been identified. Analyses of the ester-bound fatty acids indicate a highly diverse microbial community, dominated by photosynthetic organisms at the surface. The delta C-13 of cyanobacterial biomarkers such as the monomethylalkanes and hopanoids are consistent with the delta C-13 measured for bulk mat (-10%o), while a GNS biomarker, wax esters (WXE), suggests a more depleted delta C-13 for GNS biomass (-16%o). This isotopic relationship is different than that observed in mats at Octopus Spring, Yellowstone National Park (YSNP) where GNS appear to grow photoheterotrophic ally. WXE abundance, while relatively low, is most pronounced in an anaerobic zone just below the cyanobacterial layer. The WXE isotope composition at GN suggests that these bacteria utilize photoautotrophy incorporating dissolved inorganic carbon (DIC) via the 3-hydroxypropionate pathway using H2S or H2.

Jahnke, Linda L.; Embaye, Tsegereda; Turk, Kendra A.; Summons, Roger E.

2002-01-01

178

Lipid components and enzymatic hydrolysis of lipids in muscle of Chinese freshwater fish  

Microsoft Academic Search

The lipid and fatty acid composition of muscle of 10 species of freshwater fish obtained from a market of Shanghai City was\\u000a examined. Total lipids (TL) ranged over 0.9–4.7% of muscle for all samples. The content of triacylglycerol (TG) in muscle\\u000a ranged over 0.2–3.4% and that of polar lipids (PL) was 0.5–1.3%. Differences of TL content were dependent on TG

Masaki Kaneniwa; Song Miao; Chunhong Yuan; Haruka Lida; Yutaka Fukuda

2000-01-01

179

Characterization of lipid DNA interactions. I. Destabilization of bound lipids and DNA dissociation.  

PubMed Central

We have recently described a method for preparing lipid-based DNA particles (LDPs) that form spontaneously when detergent-solubilized cationic lipids are mixed with DNA. LDPs have the potential to be developed as carriers for use in gene therapy. More importantly, the lipid-DNA interactions that give rise to particle formation can be studied to gain a better understanding of factors that govern lipid binding and lipid dissociation. In this study the stability of lipid-DNA interactions was evaluated by measurement of DNA protection (binding of the DNA intercalating dye TO-PRO-1 and sensitivity to DNase I) and membrane destabilization (lipid mixing reactions measured by fluorescence resonance energy transfer techniques) after the addition of anionic liposomes. Lipid-based DNA transfer systems were prepared with pInexCAT v.2.0, a 4.49-kb plasmid expression vector that contains the marker gene for chloramphenicol acetyltransferase (CAT). LDPs were prepared using N-N-dioleoyl-N,N-dimethylammonium chloride (DODAC) and either 1, 2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) or 1, 2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE). For comparison, liposome/DNA aggregates (LDAs) were also prepared by using preformed DODAC/DOPE (1:1 mole ratio) and DODAC/DOPC (1:1 mole ratio) liposomes. The addition of anionic liposomes to the lipid-based DNA formulations initiated rapid membrane destabilization as measured by the resonance energy transfer lipid-mixing assay. It is suggested that lipid mixing is a reflection of processes (contact, dehydration, packing defects) that lead to formulation disassembly and DNA release. This destabilization reaction was associated with an increase in DNA sensitivity to DNase I, and anionic membrane-mediated destabilization was not dependent on the incorporation of DOPE. These results are interpreted in terms of factors that regulate the disassembly of lipid-based DNA formulations. PMID:9675205

Harvie, P; Wong, F M; Bally, M B

1998-01-01

180

Distribution of neutral lipids in the lipid droplet core.  

PubMed

Cholesteryl esters (CEs) are a form of cholesterol (CHOL) storage in the living cells, as opposed to free CHOL. CEs are major constituents of low density lipoprotein particles. Therefore, CEs are implicated in provoking atherosclerosis. Arranged into cytoplasmic lipid droplets (LDs), CEs are stored intracellularly. They can also be transported extracellularly by means of lipoproteins. In this work, large-scale molecular dynamics (MD) simulations are used to characterize the molecular structure of LDs containing various fractions (10-50 mol %) of cholesteryl oleate (CO) with respect to triolein (TO) fraction. The simulated LDs were covered by a phospholipid monolayer formed by a mixture of 1-palmitoyl-2-oleoylphosphatidylcholine, POPC (75 mol %), and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine, POPE (25 mol %), molecules. We report that most CO molecules are located within the hydrophobic core of LDs, whereas a small fraction (0.3-1.9 mol %) penetrates the monolayer. The solubility of CO in the phospholipid monolayer is relatively small. Due to a good miscibility with TO molecules, CO forms a liquid phase inside LD at 333 K. There is long-range order in the liquid TO-CO droplet core up to 8 nm from the phospholipid interface, resulting from the structuring of hydrophilic groups. This structuring slowly decays in the direction toward the LD center of mass. No sorting of TO and CO is detected, irrespective of the molar fractions simulated. The distribution of CO within the LDs is significant in determining the rate of their hydrolysis by surface-bound enzyme lipases, and thus has a subsequent impact on the levels of CO in plasma and LDLs. PMID:25188363

Chaban, Vitaly V; Khandelia, Himanshu

2014-09-25

181

Metabolic Regulation by Lipid Activated Receptors  

E-print Network

determine the contribution of elevated EC signaling to plasma lipid and lipoprotein metabolism, independent of food intakedetermine the ability of elevated endocannabinoid to stimulate hepatic steatosis and alter hepatic gene expression independent of food intake.

Ruby, Maxwell A.

2010-01-01

182

Surface tension and electroporation of lipid bilayers  

E-print Network

Electroporation of lipid bilayers is widely used in DNA transfection, gene therapy, and targeted drug delivery and has potential applications in water desalination and filtration. A better, more thorough molecular understanding ...

Cho, Han-Jae Jeremy

2011-01-01

183

Lymphatic Lipid Transport: Sewer or Subway?  

PubMed Central

The lymphatics began receiving attention in the scientific community as early as 1622, when Gasparo Aselli noted the appearance of milky white vessels in the mesentery of a well-fed dog. Since this time, the lymphatic system has been historically regarded as the sewer of the vasculature, passively draining fluid and proteins from the interstitial spaces (along with lipid from the gut) into the blood. Recent reports, however, suggest that the lymphatic role in lipid transport is an active and intricate process and when lymphatic function is compromised, there are systemic consequences to lipid metabolism and transport. This review highlights these recent findings and suggests future directions for understanding the interplay between lymphatic and lipid biology in health and disease. PMID:20541951

Dixon, J. Brandon

2010-01-01

184

Voltage-Gated Lipid Ion Channels  

PubMed Central

Synthetic lipid membranes can display channel-like ion conduction events even in the absence of proteins. We show here that these events are voltage-gated with a quadratic voltage dependence as expected from electrostatic theory of capacitors. To this end, we recorded channel traces and current histograms in patch-experiments on lipid membranes. We derived a theoretical current-voltage relationship for pores in lipid membranes that describes the experimental data very well when assuming an asymmetric membrane. We determined the equilibrium constant between closed and open state and the open probability as a function of voltage. The voltage-dependence of the lipid pores is found comparable to that of protein channels. Lifetime distributions of open and closed events indicate that the channel open distribution does not follow exponential statistics but rather power law behavior for long open times. PMID:23823188

Blicher, Andreas; Heimburg, Thomas

2013-01-01

185

Supported lipid bilayer/carbon nanotube hybrids  

NASA Astrophysics Data System (ADS)

Carbon nanotube transistors combine molecular-scale dimensions with excellent electronic properties, offering unique opportunities for chemical and biological sensing. Here, we form supported lipid bilayers over single-walled carbon nanotube transistors. We first study the physical properties of the nanotube/supported lipid bilayer structure using fluorescence techniques. Whereas lipid molecules can diffuse freely across the nanotube, a membrane-bound protein (tetanus toxin) sees the nanotube as a barrier. Moreover, the size of the barrier depends on the diameter of the nanotube-with larger nanotubes presenting bigger obstacles to diffusion. We then demonstrate detection of protein binding (streptavidin) to the supported lipid bilayer using the nanotube transistor as a charge sensor. This system can be used as a platform to examine the interactions of single molecules with carbon nanotubes and has many potential applications for the study of molecular recognition and other biological processes occurring at cell membranes.

Zhou, Xinjian; Moran-Mirabal, Jose M.; Craighead, Harold G.; McEuen, Paul L.

2007-03-01

186

Composite S-layer lipid structures  

PubMed Central

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

Schuster, Bernhard; Sleytr, Uwe B.

2010-01-01

187

Trypanosoma cruzi Infection and Host Lipid Metabolism  

PubMed Central

Trypanosoma cruzi is the causative agent of Chagas disease. Approximately 8 million people are thought to be affected worldwide. Several players in host lipid metabolism have been implicated in T. cruzi-host interactions in recent research, including macrophages, adipocytes, low density lipoprotein (LDL), low density lipoprotein receptor (LDLR), and high density lipoprotein (HDL). All of these factors are required to maintain host lipid homeostasis and are intricately connected via several metabolic pathways. We reviewed the interaction of T. cruzi with each of the relevant host components, in order to further understand the roles of host lipid metabolism in T. cruzi infection. This review sheds light on the potential impact of T. cruzi infection on the status of host lipid homeostasis. PMID:25276058

Miao, Qianqian

2014-01-01

188

ER stress and hepatic lipid metabolism  

PubMed Central

The endoplasmic reticulum (ER) is an important player in regulating protein synthesis and lipid metabolism. Perturbation of ER homeostasis, referred as “ER stress,” has been linked to numerous pathological conditions, such as inflammation, cardiovascular diseases, and metabolic disorders. The liver plays a central role in regulating nutrient and lipid metabolism. Accumulating evidence implicates that ER stress disrupts lipid metabolism and induces hepatic lipotoxicity. Here, we review the major ER stress signaling pathways, how ER stress contributes to the dysregulation of hepatic lipid metabolism, and the potential causative mechanisms of ER stress in hepatic lipotoxicity. Understanding the role of ER stress in hepatic metabolism may lead to the identification of new therapeutic targets for metabolic diseases. PMID:24847353

Zhou, Huiping; Liu, Runping

2014-01-01

189

Single Molecule Probes of Lipid Membrane Structure  

E-print Network

-M) using p-polarized excitation can reveal single-molecule orientations when spherical aberrations are introduced into the optics train. This approach was used here to measure the orientation of fluorescent lipid analogs doped into Langmuir...

Livanec, Philip W.

2009-12-14

190

A multivitamin infusion prevents lipid peroxidation and improves transplantation performance  

Microsoft Academic Search

A multivitamin infusion prevents lipid peroxidation and improves transplantation performance. The objective of this study was to test the hypothesis that ischemia reperfusion damage in kidney transplantation is associated with lipid peroxidation and that inhibition of lipid peroxidation by antioxidants improves the function of the transplanted kidney. Lipid peroxidation was assessed by measuring the plasma malonaldehyde content (as thiobarbituric acid

Hans Rabl; Gholamali Khoschsorur; Thomas Colombo; Peter Petritsch; Michael Rauchenwald; Peter Költringer; Franz Tatzber; Hermann Esterbauer

1993-01-01

191

Lipid rafts in T cell signalling and disease  

Microsoft Academic Search

Lipid rafts is a blanket term used to describe distinct areas in the plasma membrane rich in certain lipids and proteins and which are thought to perform diverse functions. A large number of studies report on lipid rafts having a key role in receptor signalling and activation of lymphocytes. In T cells, lipid raft involvement was demonstrated in the early

Elizabeth C. Jury; Fabian Flores-Borja; Panagiotis S. Kabouridis

2007-01-01

192

Essential Role of Lipid Raft in Ischemic Preconditioning  

Microsoft Academic Search

Lipid rafts represent a subcompartment of the plasma membrane that coordinate and regulate varieties of signaling processes while caveolins are the integral membrane protein of the lipid raft. To study the role of lipid raft in ischemic preconditioning (PC) of the heart, rat hearts were perfused by working mode and then preconditioned in absence or presence of a lipid raft

Manika Das; Mihaela Gherghiceanu; Istvan Lekli; Subhendu Mukherjee; Lawrence M. Popescu; Dipak K. Das

2008-01-01

193

A Role for Lipid Shells in Targeting Proteins to Caveolae, Rafts, and Other Lipid Domains  

NSDL National Science Digital Library

The surface membrane of cells is studded with morphologically distinct regions, or domains, like microvilli, cell-cell junctions, and coated pits. Each of these domains is specialized for a particular function, such as nutrient absorption, cell-cell communication, and endocytosis. Lipid domains, which include caveolae and rafts, are one of the least understood membrane domains. These domains are high in cholesterol and sphingolipids, have a light buoyant density, and function in both endocytosis and cell signaling. A major mystery, however, is how resident molecules are targeted to lipid domains. Here, we propose that the molecular address for proteins targeted to lipid domains is a lipid shell.

Richard G. W. Anderson (University of Texas Southwestern Medical Center, University of North Carolina School of Medicine;Department of Cell Biology, Department of Cell and Developmental Biology and Lineberger Comprehensive Cancer Center); Ken Jacobson (University of Texas Southwestern Medical Center, University of North Carolina School of Medicine;Department of Cell Biology, Department of Cell and Developmental Biology and Lineberger Comprehensive Cancer Center)

2008-06-07

194

A Role for Lipid Shells in Targeting Proteins to Caveolae, Rafts, and Other Lipid Domains  

NASA Astrophysics Data System (ADS)

The surface membrane of cells is studded with morphologically distinct regions, or domains, like microvilli, cell-cell junctions, and coated pits. Each of these domains is specialized for a particular function, such as nutrient absorption, cell-cell communication, and endocytosis. Lipid domains, which include caveolae and rafts, are one of the least understood membrane domains. These domains are high in cholesterol and sphingolipids, have a light buoyant density, and function in both endocytosis and cell signaling. A major mystery, however, is how resident molecules are targeted to lipid domains. Here, we propose that the molecular address for proteins targeted to lipid domains is a lipid shell.

Anderson, Richard G. W.; Jacobson, Ken

2002-06-01

195

Metabolic engineering of lipid catabolism increases microalgal lipid accumulation without compromising growth.  

PubMed

Biologically derived fuels are viable alternatives to traditional fossil fuels, and microalgae are a particularly promising source, but improvements are required throughout the production process to increase productivity and reduce cost. Metabolic engineering to increase yields of biofuel-relevant lipids in these organisms without compromising growth is an important aspect of advancing economic feasibility. We report that the targeted knockdown of a multifunctional lipase/phospholipase/acyltransferase increased lipid yields without affecting growth in the diatom Thalassiosira pseudonana. Antisense-expressing knockdown strains 1A6 and 1B1 exhibited wild-type-like growth and increased lipid content under both continuous light and alternating light/dark conditions. Strains 1A6 and 1B1, respectively, contained 2.4- and 3.3-fold higher lipid content than wild-type during exponential growth, and 4.1- and 3.2-fold higher lipid content than wild-type after 40 h of silicon starvation. Analyses of fatty acids, lipid classes, and membrane stability in the transgenic strains suggest a role for this enzyme in membrane lipid turnover and lipid homeostasis. These results demonstrate that targeted metabolic manipulations can be used to increase lipid accumulation in eukaryotic microalgae without compromising growth. PMID:24248374

Trentacoste, Emily M; Shrestha, Roshan P; Smith, Sarah R; Glé, Corine; Hartmann, Aaron C; Hildebrand, Mark; Gerwick, William H

2013-12-01

196

Lipids of the seeds of Cynoglossum officinale  

Microsoft Academic Search

The compositions of the lipids and fatty acids of the seeds ofCynoglossum officinale, familyBoraginaceae have been established. The bulk of the lipids consisted of netural compounds (95.2%), while the amounts of glycolipids and\\u000a phospholipids were 3.1 and 1.7%, respectively. Among the fatty acids, in addition to the usual components, acids characteristic\\u000a for theBoraginaceae family have been found: 18:3 (6, 9,

N. T. Ul'chenko; I. P. Nazarova; A. I. Glushenkova; F. F. Fatkhiev; G. A. Tolstikov

1991-01-01

197

Lipid biosynthesis in cultures of oilseed rape  

Microsoft Academic Search

Summary  This review focuses on how microspore-derived (MD) embros and cell suspension cultures of oilseed rape have been used to advance\\u000a our understanding of the biochemistry and molecular biology of lipid biosynthesis in plants. Both types of cultures are easily\\u000a maintained and circumvent the difficulties associated with using developing seeds for investigations of lipid biosynthesis.\\u000a Developing MD embryos exhibit a similar

Randall J. Weselake

2000-01-01

198

Lipid II as a target for antibiotics  

Microsoft Academic Search

Lipid II is a membrane-anchored cell-wall precursor that is essential for bacterial cell-wall biosynthesis. The effectiveness of targeting Lipid II as an antibacterial strategy is highlighted by the fact that it is the target for at least four different classes of antibiotic, including the clinically important glycopeptide antibiotic vancomycin. However, the growing problem of bacterial resistance to many current drugs,

Ben de Kruijff; Eefjan Breukink

2006-01-01

199

Membrane Cholesterol, Protein Phosphorylation, and Lipid Rafts  

NSDL National Science Digital Library

The functions of cholesterol and membrane microdomains in transmembrane signaling remain controversial. Edidin discusses the questions surrounding lipid rafts, membrane microdomains that have been biochemically defined but are difficult to visualize in vivo. He also discusses whether experiments showing correlation of changes in plasma membrane cholesterol with differentiation and the formation of adherens junctions in endothelial cells are consistent with a model in which lipid rafts influence the regulation of these processes.

Michael Edidin (Johns Hopkins University;Department of Biology REV)

2001-01-30

200

Hedgehog Signaling: A Tale of Two Lipids  

NSDL National Science Digital Library

Hedgehog proteins constitute one of the major classes of intercellular signals that control inductive interactions during animal development. These proteins undergo unusual lipid modifications and signal through an unconventional transmembrane protein receptor that is characterized by a sequence motif implicated in sterol sensing. Recent studies suggest that the lipid adducts regulate the range and potency of the signals, whereas the sterol-sensing domain is essential for receptor activity.

Philip Ingham (University of Sheffield;Medical Research Council (MRC) Intercellular Signalling Group, Centre for Developmental Genetics, School of Medicine and Biomedical Science)

2001-11-30

201

Perfluorooctanoic acid rigidifies a model lipid membrane  

NASA Astrophysics Data System (ADS)

We report a combined dynamic light scattering and neutron spin-echo (NSE) study on vesicles composed of the phospholipid 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine under the influence of varying amounts of perfluorooctanoic acid. We study local lipid bilayer undulations using NSE on time scales up to 200 ns. Similar to the effect evoked by cholesterol, we attribute the observed lipid bilayer stiffening to a condensing effect of the perfluorinated compound on the membrane.

Brüning, B.; Farago, B.

2014-04-01

202

Perfluorooctanoic acid rigidifies a model lipid membrane  

E-print Network

We report a combined dynamic light scattering and neutron spin-echo (NSE) study on vesicles composed of the phospholipid 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine under the influence of varying amounts of perfluorooctanoic acid. We study local lipid bilayer undulations using NSE on time scales up to 200 ns. Similar to the effect evoked by cholesterol, we attribute the observed lipid bilayer stiffening to a condensing effect of the perfluorinated compound on the membrane.

Beate-Annette Bruening; Bela Farago

2014-05-05

203

Lipid rafts and B-cell activation  

Microsoft Academic Search

The B-cell antigen receptor acts during B-cell activation both to initiate signalling cascades and to transport antigen into the cell for subsequent processing and presentation. Recent evidence indicates that membrane microdomains, termed lipid rafts, have a role in B-cell activation as platforms for B-cell receptor (BCR) signalling and might also act in antigen trafficking. Lipid rafts might facilitate the regulation

Susan K. Pierce

2002-01-01

204

Hepatic lipid droplets. Isolation, morphology and composition  

PubMed Central

The floating lipid layer isolated centrifugation of rat liver was examined for composition and ultrastructure. It was chiefly composed of triglycerides and cholesterol esters plus much smaller amounts of free cholesterol, diglycerides, phospholipid and protein. No free fatty acids were detected. The triglyceride and cholesterol ester fractions consisted mostly of esters of linoleic acid, oleic acid and palmitic acid. Electron micrographs of the floating lipid layer revealed numerous spherical osmiophilic droplets having a mean diameter of 0.5–2?m with a very-thin dense outer coat. Similar structures were observed as organelles in electron micrographs of the intact liver cell. The amount of triglyceride in the layer decreased in rats starved for 72h, but pellet triglyceride (homogenate minus the floating lipid layer) was unchanged. These results suggest that the floating lipid layer is the representative in vitro of lipid-rich organelles which probably function as a depot form of hepatic-cell neutral lipid. ImagesPLATE 1 PMID:4353447

DiAugustine, Richard P.; Schaefer, Joan-Marie; Fouts, James R.

1973-01-01

205

Lipids of Branhamella catarrhalis and Neisseria gonorrhoeae.  

PubMed Central

Three strains of Branhamella catarrhalis and three strains of Neisseria gonorrhoeae were analyzed with regard to their phospholipid and neutral lipid composition. B. catarrhalis (ATCC 23246) contained 5.12 +/- 0.34% lipid, determined gravimetrically, compared to 8.56 +/- 0.15% and 9.73 +/- 0.06% for two strains of N. gonorrhoeae. Cardiolipin, phosphatidylglycerol, and phosphatidyl-ethanolamine were identified in extracts of both species. In addition, B. catarrhalis contained small amounts of phosphatidylcholine, and N. gonorrhoeae contained small amounts of lyso-phosphatidylethanolamine, which accumulated with autolysis accompanying late cell culture growth. The kinetics of change of relative amounts of phospholipids in both species were measured and found to differ substantially. Neutral lipid accounted for 30.4% of the total lipid of B. catarrhalis (ATCC 23246) and 7.6% of the total lipid of N. gonorrhoeae NYH 002. Hydrocarbons, triglycerides, free fatty acids, coenzyme Q, diglycerides, and free hydroxy fatty acids were identified in the neutral lipid fraction of both species. The three strains of N. gonorrhoeae, sensitive, intermediate, and resistant to penicillin, exhibited no significant difference in the composition or metabolism of phospholipid. Images PMID:819418

Beebe, J L; Wlodkowski, T J

1976-01-01

206

Lipids, curvature, and nano-medicine*  

PubMed Central

The physical properties of the lamellar lipid-bilayer component of biological membranes are controlled by a host of thermodynamic forces leading to overall tensionless bilayers with a conspicuous lateral pressure profile and build-in curvature-stress instabilities that may be released locally or globally in terms of morphological changes. In particular, the average molecular shape and the propensity of the different lipid and protein species for forming non-lamellar and curved structures are a source of structural transitions and control of biological function. The effects of different lipids, sterols, and proteins on membrane structure are discussed and it is shown how one can take advantage of the curvature-stress modulations brought about by specific molecular agents, such as fatty acids, lysolipids, and other amphiphilic solutes, to construct intelligent drug-delivery systems that function by enzymatic triggering via curvature. Practical applications: The simple concept of lipid molecular shape and how it impacts on the structure of lipid aggregates, in particular the curvature and curvature stress in lipid bilayers and liposomes, can be exploited to construct liposome-based drug-delivery systems, e.g., for use as nano-medicine in cancer therapy. Non-lamellar-forming lysolipids and fatty acids, some of which may be designed to be prodrugs, can be created by phospholipase action in diseased tissues thereby providing for targeted drug release and proliferation of molecular entities with conical shape that break down the permeability barrier of the target cells and may hence enhance efficacy. PMID:22164124

Mouritsen, Ole G

2011-01-01

207

Partial molecular volumes of lipids and cholesterol  

PubMed Central

Volumetric measurements are reported for fully hydrated lipid/cholesterol bilayer mixtures using the neutral flotation method. Apparent specific volume data were obtained with the lipids DOPC, POPC and DMPC at T = 30 °C, DPPC at 50 °C, and brain sphingomyelin (BSM) at 45 and 24 °C for mole fractions of cholesterol x from 0 to 0.5. Unlike previous cholesterol mixture studies, we converted our raw data to partial molecular volume VL of the lipid and VC of the cholesterol. The partial molecular volumes were constant for POPC and DOPC as x was varied, but had sharp breaks for the other lipids at values of xC near 0.25 ± 0.05. Results for x < xC clearly exhibit the condensation effect of cholesterol on DPPC, DMPC and BSM when measured at temperatures above their main transition temperatures TM. The break points at xC are compared to phase diagrams in the literature. For x > xC the values of the partial molecular volumes of cholesterol clustered near 630 ± 10 Å3 in all the lipids when measured for T > TM; we suggest that this is the most appropriate measure of the bare volume of cholesterol in lipid bilayers. PMID:16737691

Greenwood, Alexander I.; Tristram-Nagle, Stephanie; Nagle, John F.

2009-01-01

208

Multiscale Modeling of Heterogeneous Lipid Bilayers  

NASA Astrophysics Data System (ADS)

The first line of defense for a cell against intrusive molecules is the membrane which must be resilient to prevent unwanted molecules from passing through as a change in the intracellular ion balance could be detrimental. Experimentally, it has been shown that as chain length and concentration of alcohols near a membrane increase, the area per lipid expands, increasing the likelihood of permeation. Additionally, there is evidence for pattern formation in cell membranes due to the presence of various lipids. These patterns or rafts are believed to play important roles in cell signaling. Here, we use MD to study the interactions between alcohols and pure lipid bilayers as well as pattern formation in mixed membranes using atomistic and coarse-grained models. We characterize the effect of alcohol chain-length and concentration on the lipid bilayer through area per head group, order parameter, and density profile. We also examine the effects of lipid-alcohol interactions on membrane curvature with the CG model and find satisfactory system representation. We use a mixture of DLPC and DSPC as model system for phase separation. Different concentrations and temperatures are used to reproduce phase transitions. We obtain agreement with experiments for area per lipid head group and deuterium order parameter. At high DSPC concentrations phase separation into a gel and liquid state is found. Simulations confirm that increasing DLPC concentrations lower the transition temperature.

Faller, Roland; Bennun-Serrano, Sandra; Dickey, Allison

2005-03-01

209

S-layer stabilized lipid membranes (Review)  

PubMed Central

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

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

2010-01-01

210

Lipid rafts of purified mouse brain synaptosomes prepared with or without detergent reveal different lipid and protein domains  

Microsoft Academic Search

Lipid rafts have been proposed to be important in a variety of functions including lipid transport, signal transduction and cell growth. There is increasing evidence that lipid rafts may play a role in cell functions in brain. Lipid rafts are typically isolated using a detergent such as Triton X-100. There has been, however, data from non-brain tissue indicating that preparation

Gunter P Eckert; Urule Igbavboa; Walter E Müller; W. Gibson Wood

2003-01-01

211

A lipid emulsion reduces mortality from clomipramine overdose in rats.  

PubMed

Tricyclic antidepressants are a common cause of self poisoning. Since these drugs are highly lipid soluble, we examined the interaction between imipramine and a lipid emulsion. Rats were given an iv dose of imipramine with either normal saline or a lipid emulsion as vehicle. The rats who received the lipid emulsion had a significantly lower mortality. The role of lipid emulsions poisoning therapy is reviewed. PMID:11824772

Yoav, Goor; Odelia, Goor; Shaltiel, Cabilil; Goor, Yoav; Goor, Odelia; Cabili, Shaltiel

2002-02-01

212

Fatty acids from membrane lipids become incorporated into lipid bodies during Myxococcus xanthus differentiation.  

PubMed

Myxococcus xanthus responds to amino acid limitation by producing fruiting bodies containing dormant spores. During development, cells produce triacylglycerides in lipid bodies that become consumed during spore maturation. As the cells are starved to induce development, the production of triglycerides represents a counterintuitive metabolic switch. In this paper, lipid bodies were quantified in wild-type strain DK1622 and 33 developmental mutants at the cellular level by measuring the cross sectional area of the cell stained with the lipophilic dye Nile red. We provide five lines of evidence that triacylglycerides are derived from membrane phospholipids as cells shorten in length and then differentiate into myxospores. First, in wild type cells, lipid bodies appear early in development and their size increases concurrent with an 87% decline in membrane surface area. Second, developmental mutants blocked at different stages of shortening and differentiation accumulated lipid bodies proportionate with their cell length with a Pearson's correlation coefficient of 0.76. Third, peripheral rods, developing cells that do not produce lipid bodies, fail to shorten. Fourth, genes for fatty acid synthesis are down-regulated while genes for fatty acid degradation are up regulated. Finally, direct movement of fatty acids from membrane lipids in growing cells to lipid bodies in developing cells was observed by pulse labeling cells with palmitate. Recycling of lipids released by Programmed Cell Death appears not to be necessary for lipid body production as a fadL mutant was defective in fatty acid uptake but proficient in lipid body production. The lipid body regulon involves many developmental genes that are not specifically involved in fatty acid synthesis or degradation. MazF RNA interferase and its target, enhancer-binding protein Nla6, appear to negatively regulate cell shortening and TAG accumulation whereas most cell-cell signals activate these processes. PMID:24906161

Bhat, Swapna; Boynton, Tye O; Pham, Dan; Shimkets, Lawrence J

2014-01-01

213

Fatty Acids from Membrane Lipids Become Incorporated into Lipid Bodies during Myxococcus xanthus Differentiation  

PubMed Central

Myxococcus xanthus responds to amino acid limitation by producing fruiting bodies containing dormant spores. During development, cells produce triacylglycerides in lipid bodies that become consumed during spore maturation. As the cells are starved to induce development, the production of triglycerides represents a counterintuitive metabolic switch. In this paper, lipid bodies were quantified in wild-type strain DK1622 and 33 developmental mutants at the cellular level by measuring the cross sectional area of the cell stained with the lipophilic dye Nile red. We provide five lines of evidence that triacylglycerides are derived from membrane phospholipids as cells shorten in length and then differentiate into myxospores. First, in wild type cells, lipid bodies appear early in development and their size increases concurrent with an 87% decline in membrane surface area. Second, developmental mutants blocked at different stages of shortening and differentiation accumulated lipid bodies proportionate with their cell length with a Pearson's correlation coefficient of 0.76. Third, peripheral rods, developing cells that do not produce lipid bodies, fail to shorten. Fourth, genes for fatty acid synthesis are down-regulated while genes for fatty acid degradation are up regulated. Finally, direct movement of fatty acids from membrane lipids in growing cells to lipid bodies in developing cells was observed by pulse labeling cells with palmitate. Recycling of lipids released by Programmed Cell Death appears not to be necessary for lipid body production as a fadL mutant was defective in fatty acid uptake but proficient in lipid body production. The lipid body regulon involves many developmental genes that are not specifically involved in fatty acid synthesis or degradation. MazF RNA interferase and its target, enhancer-binding protein Nla6, appear to negatively regulate cell shortening and TAG accumulation whereas most cell-cell signals activate these processes. PMID:24906161

Bhat, Swapna; Boynton, Tye O.; Pham, Dan; Shimkets, Lawrence J.

2014-01-01

214

Identification of lipids and lipid-binding proteins in phloem exudates from Arabidopsis thaliana  

PubMed Central

The phloem plays a crucial role in assimilate and nutrient transport, pathogen response, and plant growth and development. Yet, few species have yielded pure phloem exudate and, if proteins need to be analysed, those species may not have sequenced genomes, making identification difficult. The enrichment of Arabidopsis thaliana phloem exudate in amounts large enough to allow for metabolite and protein analysis is described. Using this method, it was possible to identify 65 proteins present in the Arabidopsis phloem exudate. The majority of these proteins could be grouped by response to pathogens, stress, or hormones, carbon metabolism, protein interaction, modification, and turnover, and transcription factors. It was also possible to detect 11 proteins that play a role in lipid/fatty acid metabolism (aspartic protease, putative 3-?-hydroxysteroid dehydrogenase, UDP-sulphoquinovose synthase/SQD1, lipase, PIG-P-like protein: phosphatidylinositol-N-acetylglucosaminyltransferase), storage (glycine-rich protein), binding (annexin, lipid-associated family protein, GRP17/oleosin), and/or signalling (annexin, putative lipase, PIG-P-like protein). Along with putative lipid-binding proteins, several lipids and fatty acids could be identified. Only a few examples exist of lipids (jasmonic acid, oxylipins) or lipid-binding proteins (DIR1, acyl-CoA-binding protein) in the phloem. Finding hydrophobic compounds in an aqueous environment is not without precedence in biological systems: human blood contains a variety of lipids, many of which play a significant role in human health. In blood, lipids are transported while bound to proteins. The present findings of lipids and lipid-binding proteins in phloem exudates suggest that a similar long-distance lipid signalling exists in plants and may play an important role in plant growth and development. PMID:22442409

Guelette, Brandon S.; Benning, Urs F.; Hoffmann-Benning, Susanne

2012-01-01

215

Genetic architecture of circulating lipid levels  

PubMed Central

Serum concentrations of low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglycerides (TGs) and total cholesterol (TC) are important heritable risk factors for cardiovascular disease. Although genome-wide association studies (GWASs) of circulating lipid levels have identified numerous loci, a substantial portion of the heritability of these traits remains unexplained. Evidence of unexplained genetic variance can be detected by combining multiple independent markers into additive genetic risk scores. Such polygenic scores, constructed using results from the ENGAGE Consortium GWAS on serum lipids, were applied to predict lipid levels in an independent population-based study, the Rotterdam Study-II (RS-II). We additionally tested for evidence of a shared genetic basis for different lipid phenotypes. Finally, the polygenic score approach was used to identify an alternative genome-wide significance threshold before pathway analysis and those results were compared with those based on the classical genome-wide significance threshold. Our study provides evidence suggesting that many loci influencing circulating lipid levels remain undiscovered. Cross-prediction models suggested a small overlap between the polygenic backgrounds involved in determining LDL-C, HDL-C and TG levels. Pathway analysis utilizing the best polygenic score for TC uncovered extra information compared with using only genome-wide significant loci. These results suggest that the genetic architecture of circulating lipids involves a number of undiscovered variants with very small effects, and that increasing GWAS sample sizes will enable the identification of novel variants that regulate lipid levels. PMID:21448234

Demirkan, Ayse; Amin, Najaf; Isaacs, Aaron; Jarvelin, Marjo-Riitta; Whitfield, John B; Wichmann, Heinz-Erich; Kyvik, Kirsten Ohm; Rudan, Igor; Gieger, Christian; Hicks, Andrew A; Johansson, Asa; Hottenga, Jouke-Jan; Smith, Johannes J; Wild, Sarah H; Pedersen, Nancy L; Willemsen, Gonneke; Mangino, Massimo; Hayward, Caroline; Uitterlinden, Andre G; Hofman, Albert; Witteman, Jacqueline; Montgomery, Grant W; Pietilainen, Kirsi H; Rantanen, Taina; Kaprio, Jaakko; Doring, Angela; Pramstaller, Peter P; Gyllensten, Ulf; de Geus, Eco JC; Penninx, Brenda W; Wilson, James F; Rivadeneria, Fernando; Magnusson, Patrik KE; Boomsma, Dorret I; Spector, Tim; Campbell, Harry; Hoehne, Birgit; Martin, Nicholas G; Oostra, Ben A; McCarthy, Mark; Peltonen-Palotie, Leena; Aulchenko, Yurii; Visscher, Peter M; Ripatti, Samuli; Janssens, A Cecile JW; van Duijn, Cornelia M

2011-01-01

216

Effect of lipid composition and packing on the adsorption of apolipoproteins to lipid monolayers  

SciTech Connect

The monolayer system has been used to study the effects of lipoprotein surface lipid composition and packing on the affinities of apolipoproteins for the surfaces of lipoprotein particles. The adsorption of apolipoproteins injected beneath lipid monolayers prepared with pure lipids or lipoprotein surface lipids is evaluated by monitoring the surface pressure of the film and the surface concentration (Gamma) of /sup 14/C-labelled apolipoprotein. At a given initial film pressure (..pi../sub i/) there is a higher adsorption of human apo A-I to unsaturated phosphatidylcholine (PC) monolayers compared to saturated PC monolayers (e.g., at ..pi../sub i/ = 10 mN/m, Gamma = 0.35 and 0.06 mg/m/sup 2/ for egg PC and distearoyl PC, respectively, with 3 x 10/sup -4/ mg/ml apo A-I in the subphase). In addition, adsorption of apo A-I is less to an egg sphingomyelin monolayer than to an egg PC monolayer. The adsorption of apo A-I to PC monolayers is decreased by addition of cholesterol. Generally, apo A-I adsorption diminishes as the lipid molecular area decreases. Apo A-I adsorbs more to monolayers prepared with HDL/sub 3/ surface lipids than with LDL surface lipids. These studies suggest that lipoprotein surface lipid composition and packing are crucial factors influencing the transfer and exchange of apolipoproteins among various lipoprotein classes during metabolism of lipoprotein particles.

Ibdah, J.A.; Lund-Katz, S.; Phillips, M.C.

1987-05-01

217

Lipid Membrane Adhesion and Fusion Driven by Designed, Minimally Multivalent Hydrogen-Bonding Lipids  

E-print Network

Lipid Membrane Adhesion and Fusion Driven by Designed, Minimally Multivalent Hydrogen-Bonding) and melamine (M) functionalized lipids can form membranes that exhibit robust hydrogen-bond driven surface bonding when incorporated at 0.1-5 mol percent in fluid phospholipid membranes, inducing both vesicle

Bong, Dennis

218

Lipid Clustering Correlates with Membrane Curvature as Revealed by Molecular Simulations of Complex Lipid Bilayers  

PubMed Central

Cell membranes are complex multicomponent systems, which are highly heterogeneous in the lipid distribution and composition. To date, most molecular simulations have focussed on relatively simple lipid compositions, helping to inform our understanding of in vitro experimental studies. Here we describe on simulations of complex asymmetric plasma membrane model, which contains seven different lipids species including the glycolipid GM3 in the outer leaflet and the anionic lipid, phosphatidylinositol 4,5-bisphophate (PIP2), in the inner leaflet. Plasma membrane models consisting of 1500 lipids and resembling the in vivo composition were constructed and simulations were run for 5 µs. In these simulations the most striking feature was the formation of nano-clusters of GM3 within the outer leaflet. In simulations of protein interactions within a plasma membrane model, GM3, PIP2, and cholesterol all formed favorable interactions with the model ?-helical protein. A larger scale simulation of a model plasma membrane containing 6000 lipid molecules revealed correlations between curvature of the bilayer surface and clustering of lipid molecules. In particular, the concave (when viewed from the extracellular side) regions of the bilayer surface were locally enriched in GM3. In summary, these simulations explore the nanoscale dynamics of model bilayers which mimic the in vivo lipid composition of mammalian plasma membranes, revealing emergent nanoscale membrane organization which may be coupled both to fluctuations in local membrane geometry and to interactions with proteins. PMID:25340788

Kolds?, Heidi; Shorthouse, David; Helie, Jean; Sansom, Mark S. P.

2014-01-01

219

Theoretical and simulation study of lipid membranes  

NASA Astrophysics Data System (ADS)

It has been established that a proper functioning of biological lipid membranes is in large part due to cholesterol's ability to regulate fluidity of a lipid bilayer. In particular, a growing body of evidence suggested that cholesterol participates in the formation of cholesterol- and sphingolipid-enriched phase-separated domains known as "rafts" in the plasma and other membranes of animal cells. Rafts have been identified as important membrane structural components in signal transduction, protein transport and sorting of membrane components. At a molecular level, the detailed, localized behavior of lipid-cholesterol bilayers is unclear. In order to better understand how cholesterols function in lipid membranes it is desirable to built theoretical models. The goal of the present research is to model lipid-cholesterol bilayers on the different length and timescales. In the first part of the work, mixtures of sphingomyelin (SM) lipid and cholesterol at different temperatures and cholesterol concentrations were investigated using Molecular Dynamics and Monte-Carlo simulation techniques. The objective was to study the properties of cholesterol- and SM-enriched raft-like domains at the atomic level. The simulations revealed that, addition of 31% cholesterol induced intermediate degree of organization in the model SM-cholesterol bilayers at temperatures below and above the main phase transition temperature of pure SM bilayer. This intermediate state of fluidity may be necessary for the binding of proteins and other molecules that associate with raft domains. In the second part of the work, dynamical self-consistent mean-field model based on atomistic simulations was developed to investigate phase properties of lipid-cholesterol bilayers on the length and timescales currently unreachable with traditional atomistic level simulation methods. This new technique allows studying systems consisting of 104 or more number of molecules, on microsecond timescales. The model was applied to dipalmitoylphosphatidylcholine lipid-cholesterol bilayers at 50°C temperature and for the range of cholesterol concentrations. Over the 20 mus simulation timescale the model predicted the continuous change in lipid chain order with increasing cholesterol content. No large-scale cholesterol-rich and cholesterol-depleted coexisting phase separated regions were observed at any cholesterol concentration.

Khelashvili, George

220

The effect of neutral helper lipids on the structure of cationic lipid monolayers  

PubMed Central

Successful drug delivery via lipid-based systems has often been aided by the incorporation of ‘helper lipids’. While these neutral lipids enhance the effectiveness of cationic lipid-based delivery formulations, many questions remain about the nature of their beneficial effects. The structure of monolayers of the cationic lipid dimethyldioctadecylammonium bromide (DODAB) alone, and mixed with a neutral helper lipid, either diolelyphosphatidylethanolamine or cholesterol at a 1 : 1 molar ratio was investigated at the air–water interface using a combination of surface pressure–area isotherms, Brewster angle microscopy (BAM) and specular neutron reflectivity in combination with contrast variation. BAM studies showed that while pure DODAB and DODAB with cholesterol monolayers showed fairly homogeneous surfaces, except in the regions of phase transition, monolayers of DODAB with diolelyphosphatidylethanolamine were, in contrast, inhomogeneous exhibiting irregular bean-shaped domains throughout. Neutron reflectivity data showed that while the thickness of the DODAB monolayer increased from 17 to 24 Å as it was compressed from a surface pressure of 5–40 mN m?1, the thickness of the helper lipid-containing monolayers, over the same range of surface pressures, was relatively invariant at between 25 and 27 Å. In addition, the monolayers containing diolelyphosphatidylethanolamine were found to be more heavily hydrated than the monolayers of cationic lipid, alone or in combination with cholesterol, with hydration levels of 18 molecules of water per molecule of lipid being recorded for the diolelyphosphatidylethanolamine-containing monolayers at a surface pressure of 30 mN m?1 compared with only six and eight molecules of water per molecule of lipid for the pure DODAB monolayer and the cholesterol-containing DODAB monolayer, respectively. PMID:21831895

Dabkowska, A. P.; Barlow, D. J.; Hughes, A. V.; Campbell, R. A.; Quinn, P. J.; Lawrence, M. J.

2012-01-01

221

Altered lipid content inhibits autophagic vesicular fusion  

PubMed Central

The autophagic/lysosomal system includes a variety of vesicular compartments that undergo dynamic fusion events. However, the characteristics and factors modulating these interactions remain, for the most part, unknown. To gain insights on the properties that govern lysosomal fusion events, we have established an in vitro fusion assay using different lysosomal/autophagic compartments isolated from mouse liver. We have found that autophagosome/lysosome fusion is a temperature-dependent process (fusion increment of 0.2±0.01%/°C), which requires ATP (1–3 mM), GTP (1–2 mM), Ca2+ (0.2–2 mM), and an acidic lysosomal pH (pH 5.2). Furthermore, changes in membrane lipid composition, induced either in vitro, by treatment with 25 mM methyl-?-cyclodextrin, or in vivo, by subjecting animals to a high-fat-diet challenge (60% kcal in fat) reduce autophagosome/lysosome fusion up to 70% of that observed in untreated fractions or from animals under a normal regular diet. These findings reveal a novel role for lipids in autophagic fusion and provide a mechanism for the reduced macroautophagic rates observed during exposure to a chronic lipid challenge. Changes in the intracellular lipid content (i.e., metabolic disorders) may thus have pronounced effects on the fusion step of macroautophagy and affect the overall activity of this intracellular proteolytic pathway.—Koga, H., Kaushik, S., Cuervo, A. M. Altered lipid content inhibits autophagic vesicular fusion. PMID:20375270

Koga, Hiroshi; Kaushik, Susmita; Cuervo, Ana Maria

2010-01-01

222

Simulation Studies of Stratum Corneum Lipid Mixtures  

PubMed Central

Abstract We present atomistic molecular dynamics results for fully hydrated bilayers composed of ceramide NS-24:0, free fatty acid 24:0 and cholesterol, to address the effect of the different components in the stratum corneum (the outermost layer of skin) lipid matrix on its structural properties. Bilayers containing ceramide molecules show higher in-plane density and hence lower rate of passive transport compared to phospholipid bilayers. At physiological temperatures, for all composition ratios explored, the lipids are in a gel phase with ordered lipid tails. However, the large asymmetry in the lengths of the two tails of the ceramide molecule leads to a fluidlike environment at the bilayer midplane. The lateral pressure profiles show large local variations across the bilayer for pure ceramide or any of the two-component mixtures. Close to the skin composition ratio, the lateral pressure fluctuations are greatly suppressed, the ceramide tails from the two leaflets interdigitate significantly, the depression in local density at the interleaflet region is lowered, and the bilayers have lowered elastic moduli. This indicates that the observed composition ratio in the stratum corneum lipid layer is responsible for both the good barrier properties and the stability of the lipid structure against mechanical stresses. PMID:19804725

Das, Chinmay; Noro, Massimo G.; Olmsted, Peter D.

2009-01-01

223

Nanosecond Lipid Dynamics in Membranes Containing Cholesterol  

SciTech Connect

Lipid dynamics in the cholesterol-rich (40 mol%) liquid-ordered (lo) phase of dimyristoylphosphatidylcholine membranes were studied using neutron spin-echo and neutron backscattering. Recent theoretical and experimental evidence supports the notion of the liquid-ordered phase in phospholipid membranes as a locally structured liquid, with small ordered domains of a highly dynamic nature in equilibrium with a disordered matrix [S. Meinhardt, R. L. C. Vink and F. Schmid, Proc. Natl. Acad. Sci. U. S. A., 2013, 110(12), 4476 4481, C. L. Armstrong et al., PLoS One, 2013, 8(6), e66162]. This local structure was found to have a pronounced impact on the membranes' dynamical properties. We found that the long-wavelength dynamics in the liquid-ordered phase, associated with the elastic properties of the membranes, were faster by two orders of magnitude as compared to the liquid disordered phase. At the same time, collective nanoscale diffusion was significantly slower. The presence of a soft-mode (a slowing down) in the longwavelength dispersion relationship suggests an upper size limit for the ordered lipid domain of ~220 A. Moreover, from the relaxation rate of the collective lipid diffusion of lipid lipid distances, the lifetime of these domains was estimated to be about 100 nanoseconds.

Armstrong, Clare L [McMaster University] [McMaster University; Haeussler, Wolfgang [FRM-II, Technische Universitaet Munchen] [FRM-II, Technische Universitaet Munchen; Seydel, Tilo [Institut Laue-Langevin (ILL)] [Institut Laue-Langevin (ILL); Katsaras, John [ORNL] [ORNL; Rheinstadter, Maikel C [McMaster University] [McMaster University

2014-01-01

224

Preservation of Microbial Lipids in Geothermal Sinters  

NASA Astrophysics Data System (ADS)

Lipid biomarkers are widely used to study the earliest life on Earth and have been invoked as potential astrobiological markers, but few studies have assessed their survival and persistence in geothermal settings. Here, we investigate lipid preservation in active and inactive geothermal silica sinters, with ages of up to 900 years, from Champagne Pool, Waiotapu, New Zealand. Analyses revealed a wide range of bacterial biomarkers, including free and bound fatty acids, 1,2-di-O-alkylglycerols (diethers), and various hopanoids. Dominant archaeal lipids include archaeol and glycerol dialkyl glycerol tetraethers (GDGTs). The predominance of generally similar biomarker groups in all sinters suggests a stable microbial community throughout Champagne Pool's history and indicates that incorporated lipids can be well preserved. Moreover, subtle differences in lipid distributions suggest that past changes in environmental conditions can be elucidated. In this case, higher archaeol abundances relative to the bacterial diethers, a greater proportion of cyclic GDGTs, the high average chain length of the bacterial diethers, and greater concentrations of hopanoic acids in the older sinters all suggest hotter conditions at Champagne Pool in the past.

Kaur, Gurpreet; Mountain, Bruce W.; Hopmans, Ellen C.; Pancost, Richard D.

2011-04-01

225

Association of stomatin with lipid bodies.  

PubMed

The oligomeric lipid raft-associated integral protein stomatin normally localizes to the plasma membrane and the late endosomal compartment. Similar to the caveolins, it is targeted to lipid bodies (LBs) on overexpression. Endogenous stomatin also associates with LBs to a small extent. Green fluorescent protein-tagged stomatin (StomGFP) and the dominant-negative caveolin-3 mutant DGV(cav3)HA occupy distinct domains on LB surfaces but eventually intermix. Studies of StomGFP deletion mutants reveal that the region for membrane association but not oligomerization and raft association is essential for LB targeting. Blocking protein synthesis leads to the redistribution of StomGFP from LBs to LysoTracker-positive vesicles indicating a connection with the late endosomal/lysosomal pathway. Live microscopy of StomGFP reveals multiple interactions between LBs and microtubule-associated vesicles possibly representing signaling events and/or the exchange of cargo. Proteomic analysis of isolated LBs identifies adipophilin and TIP47, various lipid-specific enzymes, cytoskeletal components, chaperones, Ras-related proteins, protein kinase D2, and other regulatory proteins. The association of the Rab proteins 1, 6, 7, 10, and 18 with LBs indicates various connections to other compartments. Our data suggest that LBs are not only involved in the storage of lipids but also participate actively in the cellular signaling network and the homeostasis of lipids. PMID:15024010

Umlauf, Ellen; Csaszar, Edina; Moertelmaier, Manuel; Schuetz, Gerhard J; Parton, Robert G; Prohaska, Rainer

2004-05-28

226

Lipid peroxidation and the aging process.  

PubMed

Consistent evidence supports the hypothesis that a progressive accumulation of oxidative damage to important cellular molecules is a fundamental mechanism involved in most senescence-associated alterations. Oxidative damage occurs when free radicals produced within an organism are not completely destroyed by the appropriate endogenous defense systems. Because lipids are a major component of living organisms and probably the first easy target of free radicals once they are produced, lipid peroxidation might play an important role in initiating and/or mediating some aspects of the aging process. It has been widely demonstrated that there is an age-associated increase in the steady-state concentrations of lipid peroxidation products. However, establishing the involvement of this phenomenon in the pathogenesis of the aging process has not been an easy task. The recent development of more reliable techniques to measure lipid peroxidation, together with more well-defined animal models of aging, should be of great help in future studies in this field. The current evidence for the presence and importance of lipid peroxidation in the aging process is discussed in this review. PMID:14603026

Praticò, Domenico

2002-12-18

227

Simulation studies of stratum corneum lipid mixtures  

E-print Network

We present atomistic molecular dynamics results for fully hydrated bilayers composed of ceramide NS-24:0, free fatty acid 24:0 and cholesterol, to address the effect of the different components in the stratum corneum (the outermost layer of skin) lipid matrix on its structural properties. Bilayers containing ceramide molecules show higher in-plane density and hence lower rate of passive transport compared to phospholipid bilayers. At physiological temperatures, for all composition ratios explored, the lipids are in a gel phase with ordered lipid tails. However, the large asymmetry in the lengths of the two tails of the ceramide molecule leads to a fluid like environment at the bilayer mid-plane. The lateral pressure profiles show large local variations across the bilayer for pure ceramide or any of the two component mixtures. Close to the skin composition ratio, the lateral pressure fluctuations are greatly suppressed, the ceramide tails from the two leaflets interdigitate significantly, the depression in local density at the inter-leaflet region is lowered, and the bilayer have lowered elastic moduli. This indicates that the observed composition ratio in the stratum corneum lipid layer is responsible for both the good barrier properties and the stability of the lipid structure against mechanical stresses.

Chinmay Das; Massimo G. Noro; Peter D. Olmsted

2009-07-03

228

Atomistic Monte Carlo Simulation of Lipid Membranes  

PubMed Central

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. PMID:24469314

Wustner, Daniel; Sklenar, Heinz

2014-01-01

229

Dividing Cells Regulate Their Lipid Composition and Localization  

PubMed Central

Summary Although massive membrane rearrangements occur during cell division, little is known about specific roles that lipids might play in this process. We report that the lipidome changes with the cell cycle. LC-MS-based lipid profiling shows that 11 lipids with specific chemical structures accumulate in dividing cells. Using AFM, we demonstrate differences in the mechanical properties of live dividing cells and their isolated lipids relative to nondividing cells. In parallel, systematic RNAi knockdown of lipid biosynthetic enzymes identified enzymes required for division, which highly correlated with lipids accumulated in dividing cells. We show that cells specifically regulate the localization of lipids to midbodies, membrane-based structures where cleavage occurs. We conclude that cells actively regulate and modulate their lipid composition and localization during division, with both signaling and structural roles likely. This work has broader implications for the active and sustained participation of lipids in basic biology. PMID:24462247

Atilla-Gokcumen, G. Ekin; Muro, Eleonora; Relat-Goberna, Josep; Sasse, Sofia; Bedigian, Anne; Coughlin, Margaret L.; Garcia-Manyes, Sergi; Eggert, Ulrike S.

2014-01-01

230

Multiscale simulations reveal conserved patterns of lipid interactions with aquaporins.  

PubMed

Interactions of membrane proteins with lipid molecules are central to their stability and function. We have used multiscale molecular dynamics simulations to determine the extent to which interactions with lipids are conserved across the aquaporin (Aqp) family of membrane proteins. Simulation-based assessment of the lipid interactions made by Aqps when embedded within a simple phospholipid bilayer agrees well with the protein-lipid contacts determined by electron diffraction from 2D crystals. Extending this simulation-based analysis to all Aqps of known structure reveals a degree of conservation of such interactions across the Aqp structural proteome. Despite similarities in the binding orientations and interactions of the lipids, there do not appear to be distinct, high-specificity lipid binding sites on the surface of Aqps. Rather Aqps exhibit a more broadly conserved protein/lipid interface, suggestive of interchange between annular and bulk lipids, instead of a fixed annular "shell" of lipids. PMID:23602661

Stansfeld, Phillip J; Jefferys, Elizabeth E; Sansom, Mark S P

2013-05-01

231

Lipids of a Sterol-Nonrequiring Mycoplasma  

PubMed Central

The lipids of the sterol nonrequiring Mycoplasma strain S743 were found to include both ester glycerophosphatides (phosphatidylglycerol, acylphosphatidylglycerol, and diphosphatidylglycerol) and ceramide glycerophosphate compounds containing N-hydroxyacyl groups. The major phosphosphingolipid was tentatively identified as a hydroxyceramidephosphorylglycerol containing an O-acyl group. These compounds became labeled during growth in the presence of 32P-orthophosphate, 14C-glycerol, or 14C-palmitate. The lipid fraction also contained free long-chain base. 14C-palmitate was converted to labeled sphinganine. The long-chain base composition of the lipids was modified by growing the organisms in media containing different fatty acids, which were converted to bases containing two more C atoms per molecule. Ninety per cent of the long-chain base from cells grown in medium supplemented with elaidate consisted of monounsaturated C20 base. Images PMID:5489436

Plackett, P.; Smith, P. F.; Mayberry, W. R.

1970-01-01

232

Apolipoprotein gene involved in lipid metabolism  

DOEpatents

Methods and materials for studying the effects of a newly identified human gene, APOAV, and the corresponding mouse gene apoAV. The sequences of the genes are given, and transgenic animals which either contain the gene or have the endogenous gene knocked out are described. In addition, single nucleotide polymorphisms (SNPs) in the gene are described and characterized. It is demonstrated that certain SNPs are associated with diseases involving lipids and triglycerides and other metabolic diseases. These SNPs may be used alone or with SNPs from other genes to study individual risk factors. Methods for intervention in lipid diseases, including the screening of drugs to treat lipid-related or diabetic diseases are also disclosed.

Rubin, Edward (Berkeley, CA); Pennacchio, Len A. (Sebastopol, CA)

2007-07-03

233

Lipid Corralling and Poloxamer Squeeze-Out in Membranes  

NASA Astrophysics Data System (ADS)

Using x-ray scattering measurements we have quantitatively determined the effect of poloxamer 188 (P188), a polymer known to seal damaged membranes, on the structure of lipid monolayers. P188 selectively inserts into low lipid-density regions of the membrane and “corrals” lipid molecules to pack tightly, leading to unexpected Bragg peaks at low nominal lipid density and inducing lipid/poloxamer phase separation. At tighter lipid packing, the once inserted P188 is squeezed out, allowing the poloxamer to gracefully exit when the membrane integrity is restored.

Wu, Guohui; Majewski, Jaroslaw; Ege, Canay; Kjaer, Kristian; Weygand, Markus Jan; Lee, Ka Yee

2004-07-01

234

Microsecond molecular dynamics simulations of lipid mixing.  

PubMed

Molecular dynamics (MD) simulations of membranes are often hindered by the slow lateral diffusion of lipids and the limited time scale of MD. In order to study the dynamics of mixing and characterize the lateral distribution of lipids in converged mixtures, we report microsecond-long all-atom MD simulations performed on the special-purpose machine Anton. Two types of mixed bilayers, POPE:POPG (3:1) and POPC:cholesterol (2:1), as well as a pure POPC bilayer, were each simulated for up to 2 ?s. These simulations show that POPE:POPG and POPC:cholesterol are each fully miscible at the simulated conditions, with the final states of the mixed bilayers similar to a random mixture. By simulating three POPE:POPG bilayers at different NaCl concentrations (0, 0.15, and 1 M), we also examined the effect of salt concentration on lipid mixing. While an increase in NaCl concentration is shown to affect the area per lipid, tail order, and lipid lateral diffusion, the final states of mixing remain unaltered, which is explained by the largely uniform increase in Na(+) ions around POPE and POPG. Direct measurement of water permeation reveals that the POPE:POPG bilayer with 1 M NaCl has reduced water permeability compared with those at zero or low salt concentration. Our calculations provide a benchmark to estimate the convergence time scale of all-atom MD simulations of lipid mixing. Additionally, equilibrated structures of POPE:POPG and POPC:cholesterol, which are frequently used to mimic bacterial and mammalian membranes, respectively, can be used as starting points of simulations involving these membranes. PMID:25237736

Hong, Chunkit; Tieleman, D Peter; Wang, Yi

2014-10-14

235

Age and ethnic variations in sebaceous lipids  

PubMed Central

This study was conducted to compare lipid components of sebum from persons from three ethnic backgrounds—Caucasian, African American and Northern Asian. Men and women with no acne in two age groups (18?25 y and 35?45 y) were recruited. Skin surface hydration (SkiCon 200EX and NovaMeter), barrier function (Delfin VapoMeter), high-resolution clinical imaging, self-assessments and two pairs of sebutapes on the forehead that extracted the lipids on the surface of their skin were used. Significant differences (p < 0.05) in skin hydration between African Americans and Caucasians in both age groups were noted, with the order from highest to lowest absolute values: African American > Northern Asian > Caucasian. Transepidermal water loss (TEWL) measurements demonstrated that African Americans and Caucasians were significantly different (p < 0.05), with the trend being the inverse of the hydration trend—Caucasian > Northern Asian > African American, which would indicate better barrier function for African Americans with a lower TEWL. African American women had more total lipid production than Northern Asian or Caucasian women. When analyzing the three lipid classes (free fatty acids, triglycerides and wax esters), the trend became significant (p < 0.05) in the wax ester fraction when directly comparing African Americans with Caucasians. Additionally, six lipids were identified in the wax ester fractions that were significantly different in quantity (p < 0.05) between African Americans and Caucasians. These results identified significant differences in sebaceous lipid profiles across ethnic groups and determined that the differences correlated with skin barrier function. PMID:24194973

Pappas, Apostolos; Fantasia, Jared; Chen, Theresa

2013-01-01

236

Lipid Rafts and Alzheimer’s Disease: Protein-Lipid Interactions and Perturbation of Signaling  

PubMed Central

Lipid rafts are membrane domains, more ordered than the bulk membrane and enriched in cholesterol and sphingolipids. They represent a platform for protein-lipid and protein–protein interactions and for cellular signaling events. In addition to their normal functions, including membrane trafficking, ligand binding (including viruses), axonal development and maintenance of synaptic integrity, rafts have also been implicated in the pathogenesis of several neurodegenerative diseases including Alzheimer’s disease (AD). Lipid rafts promote interaction of the amyloid precursor protein (APP) with the secretase (BACE-1) responsible for generation of the amyloid ? peptide, A?. Rafts also regulate cholinergic signaling as well as acetylcholinesterase and A? interaction. In addition, such major lipid raft components as cholesterol and GM1 ganglioside have been directly implicated in pathogenesis of the disease. Perturbation of lipid raft integrity can also affect various signaling pathways leading to cellular death and AD. In this review, we discuss modulation of APP cleavage by lipid rafts and their components, while also looking at more recent findings on the role of lipid rafts in signaling events. PMID:22737128

Hicks, David A.; Nalivaeva, Natalia N.; Turner, Anthony J.

2012-01-01

237

Lipid analysis of a ground sloth coprolite  

NASA Astrophysics Data System (ADS)

Coprolites can provide detailed information about the nutritional habits and digestive processes of the animals that produced them and may also yield information about the palaeoenvironment in which the animal existed. To test the utility of the lipid biomarker approach to coprolite analysis, lipids were extracted from a coprolite of the Pleistocene ground sloth Nothrotheriops shastensis. Gas chromatography/mass spectrometry results revealed a dominant spiroketal sapogenin component identified, using nuclear magnetic resonance spectroscopy, as epismilagenin. The dominance of epismilagenin is probably due to ingestion of Yucca spp. and Agave spp., which is consistent with previous studies on the diet of this species.

Gill, Fiona L.; Crump, Matthew P.; Schouten, Remmert; Bull, Ian D.

2009-09-01

238

Computationally efficient prediction of area per lipid  

NASA Astrophysics Data System (ADS)

Area per lipid (APL) is an important property of biological and artificial membranes. Newly constructed bilayers are characterized by their APL and newly elaborated force fields must reproduce APL. Computer simulations of APL are very expensive due to slow conformational dynamics. The simulated dynamics increases exponentially with respect to temperature. APL dependence on temperature is linear over an entire temperature range. I provide numerical evidence that thermal expansion coefficient of a lipid bilayer can be computed at elevated temperatures and extrapolated to the temperature of interest. Thus, sampling times to predict accurate APL are reduced by a factor of ?10.

Chaban, Vitaly

2014-11-01

239

Aluminum stress response in rice: effects on membrane lipid composition and expression of lipid biosynthesis genes.  

PubMed

The presence of aluminum (Al) in acidic soils is a major abiotic stress limiting the production of cultivated plants. Cell membranes are the main targets of environmental stresses and there is growing evidence for the involvement of membrane lipids in plant adaptation. The aim of this study was to evaluate the mid-long effects of Al on membrane lipid content and composition in the roots and shoots of rice plants grown under hydroponic conditions. Four rice cultivars were compared: two acknowledged as Al-resistant (Koshihikari) and Al-sensitive (Kasalath), respectively, and two Vietnamese cultivars, OM6073 and OM1490. Al treatment inhibited root and shoot growth in the sensitive cultivars and the observed changes in root and shoot lipid and fatty acid composition revealed patterns associated with Al sensitivity: larger decreases in lipid content and decreases in fatty acid unsaturation. In the roots, phospholipids, and particularly phosphatidylcholine (PC), decreased dramatically in the susceptible cultivars whereas the amount of lipid classes remained unchanged in the tolerant ones. In the shoots, the glycolipids monogalactosyldiacylglycerol and digalactosyldiacylglycerol as well as PC were mostly affected by Al treatment in the susceptible varieties. mRNA accumulation corresponding to genes coding for galactolipid synthases, enzymes of the PC and phosphatidylethanolamine biosynthetic pathways and fatty acid desaturases correlated well with changes in lipid contents in roots and partly explained lipid changes in leaves. The results suggested that the capacity to maintain the proper functioning of some lipid biosynthetic activities and hence the stability of lipid composition may help the rice plant to withstand Al stress. PMID:22452575

Huynh, Van-Biet; Repellin, Anne; Zuily-Fodil, Yasmine; Pham-Thi, Anh-Thu

2012-11-01

240

Inclusion of the helper lipid dioleoyl-phosphatidylethanolamine in solid lipid nanoparticles inhibits their transfection efficiency.  

PubMed

Solid lipid nanoparticles (SLNs) are a promising system for the delivery of lipophilic and hydrophilic drugs. They consist of a solid lipid core that is stabilized by a layer of surfactants. By the incorporation of cationic lipids in the formulation, positively charged SLNs can be generated, that are suitable carriers for nucleic acids (DNA, siRNA). Considering the beneficial effect of helper lipids on the transfection efficiency with cationic liposomes, the effect of the helper lipid 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) on transfection with cationic lipid-containing solid lipid nanoparticles was investigated in PC3 prostate cancer cells. The inclusion of DOPE in SLN formulations, instead of promoted, strongly inhibited SLN transfection efficiency, by frustrating the accommodation of DNA by the particles, as was revealed by biochemical analysis. SLNs devoid of DOPE maintained a homogenous size distribution of approximately 150 nm following lipoplex assembly and cellular delivery, and showed transfection efficiency comparable to that of Lipofectamine 2000' (LF2k). Moreover, the SLNs maintain their high transfection efficiency after lyophilization and long-term storage (1-2 years), an important asset for biomedical applications. There is even the possibility to lyophilize the SLN carrier together with its DNA cargo, which represents an interesting pharmaceutical advantage of the SLN formulations over LF2k. These results reflect marked differences between the physicochemical properties of cationic liposomes and SLNs, the latter requiring more critical lipid-depending properties for effective 'packaging' of DNA but displaying a higher storage stability than cationic lipid based carriers like LF2k. PMID:24738343

de Jesus, Marcelo B; Radaic, Allan; Hinrichs, Wouter L J; Ferreira, Carmen V; de Paula, Eneida; Hoekstra, Dick; Zuhorn, Inge S

2014-02-01

241

An ER protein functionally couples neutral lipid metabolism on lipid droplets to membrane lipid synthesis in the ER  

PubMed Central

Eukaryotic cells store neutral lipids, such as triacylglycerol (TAG), in lipid droplets (LDs). Here, we have addressed how LDs are functionally linked to the endoplasmic reticulum (ER). We show in S. cerevisiae that LD growth is sustained by LD-localized enzymes. When LDs grow in early stationary phase, the diacylglycerol acyl-transferase Dga1p moves from the ER to LDs and is responsible for all TAG synthesis from diacylglycerol (DAG). During LD breakdown in early exponential phase, an ER membrane protein, Ice2p, facilitates TAG utilization for membrane-lipid synthesis. Ice2p has a cytosolic domain with affinity for LDs and is required for the efficient utilization of LD-derived DAG in the ER. Ice2p breaks a futile cycle on LDs between TAG-degradation and -synthesis, promoting the rapid re-localization of Dga1p to the ER. Our results show that Ice2p functionally links LDs with the ER, and explain how cells switch neutral lipid metabolism from storage to consumption. PMID:24373967

Markgraf, Daniel F.; Klemm, Robin W.; Junker, Mirco; Hannibal-Bach, Hans K.; Ejsing, Christer S.; Rapoport, Tom A.

2014-01-01

242

Supported lipid bilayer nanosystems: stabilization by undulatory-protrusion forces and destabilization by lipid bridging.  

PubMed

Control of the stabilization/destabilization of supported lipid bilayers (SLBs) on nanoparticles is important for promotion of their organized assembly and for their use as delivery vehicles. At the same time, understanding the mechanism of these processes can yield insight into nanoparticle-cell interactions and nanoparticle toxicity. In this study, the suspension/precipitation process of zwitterionic lipid/SiO(2) nanosystems was analyzed as a function of ionic strength and as a function of the ratio of lipid/SiO(2) surface areas, at pH = 7.6. Salt is necessary to induce supported lipid bilayer (SLB) formation for zwitterionic lipids on silica (SiO(2)) (Seantier, B.; Kasemo, B., Influence of Mono- and Divalent Ions on the Formation of Supported Phospholipid Bilayers via Vesicle Adsorption. Langmuir 2009, 25 (10), 5767-5772). However, for zwitterionic SLBs on SiO(2) nanoparticles, addition of salt can cause precipitation of the SLBs, due to electrostatic shielding by both the lipid and the salt and to the suppression of thermal undulation/protrusion repulsive forces for lipids on solid surfaces. At ionic strengths that cause precipitation of SLBs, it was found that addition of excess SUVs, at ratios where there were equal populations of SUVs and SLBs, restored the undulation/protrusion repulsive forces and restabilized the suspensions. We suggest that SUVs separate SLBs in the suspension, as observed by TEM, and that SLB-SLB interactions are replaced by SLB-SUV interactions. Decreasing the relative amount of lipid, to the extent that there was less lipid available than the amount required for complete bilayer coverage of the SiO(2), resulted in precipitation of the nanosystem by a process of nanoparticle lipid bridging. For this case, we postulate a process in which lipid bilayer patches on one nanoparticle collide with bare silica patches on another SiO(2) nanoparticle, forming a single bilayer bridge between them. TEM data confirmed these findings, thus indicating that lipid bridges are composed of half bilayers on adjoining SiO(2) nanoparticles. PMID:21500811

Savarala, Sushma; Monson, Frederick; Ilies, Marc A; Wunder, Stephanie L

2011-05-17

243

Long and Short Lipid Molecules Experience the Same Interleaflet Drag in Lipid Bilayers  

NASA Astrophysics Data System (ADS)

Membrane interleaflet viscosity ?e affects tether formation, phase separation into domains, cell shape changes, and budding. Contrary to the expected contribution to interleaflet coupling from interdigitation, the slide of lipid patches in opposing monolayers conferred the same value ?e?3×109Jsm-4 for the friction experienced by the ends of both short and long chain fluorescent lipid analogues. Consistent with the weak dependence of the translational diffusion coefficient on lipid length, the in-layer viscosity was, albeit length dependent, much smaller than ?e.

Horner, Andreas; Akimov, Sergey A.; Pohl, Peter

2013-06-01

244

Lipid bilayer and cytoskeletal interactions in a red blood cell  

E-print Network

We study the biomechanical interactions between the lipid bilayer and the cytoskeleton in a red blood cell (RBC) by developing a general framework for mesoscopic simulations. We treated the lipid bilayer and the cytoskeleton ...

Peng, Zhangli

245

An emerging role of mTOR in lipid biosynthesis  

E-print Network

Lipid biosynthesis is essential for the maintenance of cellular homeostasis. The lipids produced by cells (glycerolipids, fatty acids, phospholipids, cholesterol, and sphingolipids) are used as an energy source/reserve, ...

Laplante, Mathieu

246

Lipid Raft: A Floating Island Of Death or Survival  

PubMed Central

Lipid rafts are microdomains of the plasma membrane enriched in cholesterol and sphingolipids, and play an important role in the initiation of many pharmacological agent-induced signaling pathways and toxicological effects. The structure of lipid rafts is dynamic, resulting in an ever-changing content of both lipids and proteins. Cholesterol, as a major component of lipid rafts, is critical for the formation and configuration of lipid rafts microdomains, which provide signaling platforms capable of activating both pro-apoptotic and anti-apoptotic signaling pathways. A change of cholesterol level can result in lipid rafts disruption and activate or deactivate raft-associated proteins, such as death receptor proteins, protein kinases, and calcium channels. Several anti-cancer drugs are able to suppress growth and induce apoptosis of tumor cells through alteration of lipid raft contents via disrupting lipid raft integrity. PMID:22289360

George, Kimberly S.; Wu, Shiyong

2012-01-01

247

Injected Omental Lipids for Treatment of Soft Tissue Injury.  

National Technical Information Service (NTIS)

Omental lipids have been shown to be potent angiogenic compounds. In several models, these lipids have improved healing. This investigation was to determine if a single injected dose could improve militarily relevant injuries frostbite and soft tissue inj...

A. Hall, C. Woodham

2011-01-01

248

Irregular bilayer structure in vesicles prepared from Halobacterium cutirubrum lipids  

NASA Technical Reports Server (NTRS)

Fluorescent probes were used to study the structure of the cell envelope of Halobacterium cutirubrum, and, in particular, to explore the effect of the heterogeneity of the lipids in this organism on the structure of the bilayers. The fluorescence polarization of perylene was followed in vesicles of unfractionated lipids and polar lipids as a function of temperature in 3.4 M solutions of NaCl, NaNO3, and KSCN, and it was found that vesicles of unfractionated lipids were more perturbed by chaotropic agents than polar lipids. The dependence of the relaxation times of perylene on temperature was studied in cell envelopes and in vesicles prepared from polar lipids, unfractionated lipids, and mixtures of polar and neutral lipids.

Lanyi, J. K.

1974-01-01

249

Hydrothermal processing of high-lipid biomass to fuels  

E-print Network

High-lipid algae are potential sources of biofuels. Lipids in this biomass provide a straightforward chemical route to hydrocarbon-based high energy-density fuels needed for diesel and jet engines. However, current schemes ...

Johnson, Michael C., Ph. D. Massachusetts Institute of Technology

2012-01-01

250

Turning the spotlight on protein-lipid interactions in cells  

PubMed Central

Protein function is largely dependent on coordinated and dynamic interactions of the protein with biomolecules including other proteins, nucleic acids and lipids. While powerful methods for global profiling of protein-protein and protein-nucleic acid interactions are available, proteome-wide mapping of protein-lipid interactions is still challenging and rarely performed. The emergence of bifunctional lipid probes with photoactivatable and clickable groups offers new chemical tools for globally profiling protein-lipid interactions under cellular contexts. In this review, we summarize recent advances in the development of bifunctional lipid probes for studying protein-lipid interactions. We also highlight how in vivo photocrosslinking reactions contribute to the characterization of lipid-binding proteins and lipidation-mediated protein-protein interactions. PMID:25129056

Peng, Tao; Yuan, Xiaoqiu; Hang, Howard C.

2014-01-01

251

Synthesis and Characterization of Betaine-like Diacyl Lipids: Zwitterionic Lipids with the Cationic Group at the Bilayer Interface  

PubMed Central

We synthesized and characterized a series of zwitterionic, acetate-terminated, quaternized amine diacyl lipids (AQ). These lipids have an inverted headgroup orientation as compared to naturally occurring phosphatidylcholine (PC) lipids; the cationic group is anchored at the membrane interface, while the anionic group extends into the aqueous phase. AQ lipids preferentially interact with highly polarizable anions (ClO4?) over less polarizable ions (Cl?), in accord with the Hofmeister series, as measured by the change in zeta potential of AQ liposomes. Conversely, AQ lipids have a weaker association with calcium than do PC lipids. The transition temperatures (Tm) of the AQ lipids are similar to the Tm observed with phosphatidylethanolamine (PE) lipids of the same chain length. AQ lipids form large lipid sheets after heating and sonication; however, in the presence of cholesterol, (Chol) these lipids form stable liposomes that encapsulate carboxyfluorescein. The AQ:Chol liposomes retain their contents in the presence of serum at 37 °C, and when injected intravenously into mice, their organ biodistribution is similar to that observed with PC:Chol liposomes. AQ lipids demonstrate that modulating the headgroup charge orientation significantly alters the biophysical properties of liposomes. For the drug carrier field, these new materials provide a non-phosphate containing zwitterlipid for the production of lipid vesicles. PMID:22301334

Kohli, Aditya G.; Walsh, Colin L.; Szoka, Francis C.

2012-01-01

252

LIPID BIOMARKER ANALYSIS OF MARINE DINOFLAGELLATES  

EPA Science Inventory

Many marine eukaryotic algae have been shown to possess characteristic chemotaxonomic lipid biomarkers. Dinoflagellates in particular are often characterized by the presence of sterols and pigments that are rarely found in other classes of algae. To evaluate the utility of chemic...

253

Lipid organization in pig stratum corneum  

Microsoft Academic Search

Abstract,The lipid and,keratin structure,of pig,stratum corneum,has been,elucidated by small- and,wide-angle X-ray structures of human,and mouse sc have been elucidated. In human SC, , lamellar structures were found with

J. A. Bouwstra; G. S. Gooris; f W. Bras; D. T. Downing

254

Engineering lipid bilayer membranes for protein studies.  

PubMed

Lipid membranes regulate the flow of nutrients and communication signaling between cells and protect the sub-cellular structures. Recent attempts to fabricate artificial systems using nanostructures that mimic the physiological properties of natural lipid bilayer membranes (LBM) fused with transmembrane proteins have helped demonstrate the importance of temperature, pH, ionic strength, adsorption behavior, conformational reorientation and surface density in cellular membranes which all affect the incorporation of proteins on solid surfaces. Much of this work is performed on artificial templates made of polymer sponges or porous materials based on alumina, mica, and porous silicon (PSi) surfaces. For example, porous silicon materials have high biocompatibility, biodegradability, and photoluminescence, which allow them to be used both as a support structure for lipid bilayers or a template to measure the electrochemical functionality of living cells grown over the surface as in vivo. The variety of these media, coupled with the complex physiological conditions present in living systems, warrant a summary and prospectus detailing which artificial systems provide the most promise for different biological conditions. This study summarizes the use of electrochemical impedance spectroscopy (EIS) data on artificial biological membranes that are closely matched with previously published biological systems using both black lipid membrane and patch clamp techniques. PMID:24185908

Khan, Muhammad Shuja; Dosoky, Noura Sayed; Williams, John Dalton

2013-01-01

255

Involvement of lipid peroxidation in platelet signalling  

Microsoft Academic Search

A well-known signalling pathway in blood platelets consists in the release of arachidonic acid (AA) from membrane phospholipids and its specific oxygenation into bioactive derivatives. In particular, cyclic prostaglandin endoperoxides and thromboxane A2 are potent inducers of platelet functions and are produced in greater amounts when the level of lipid hydroperoxides is higher than normal, as ‘physiological concentrations’ of such

M. Lagarde; D. Lemaitre; C. Calzada; E. Véricel

1997-01-01

256

Lipid droplet targeting domains of adipophilin  

Microsoft Academic Search

Adipophilin (ADPH), a prominent protein com- ponent of lipid storage droplets (LSDs), is postulated to be necessary for the formation and cellular function of these structures. The presence of significant sequence similarities within an ? 100 amino acid region of the N-terminal por- tions of ADPH and related LSD binding proteins, perilipin and TIP47, has implicated this region, known as

James L. McManaman; William Zabaronick; Jerome Schaack; David J. Orlicky

2003-01-01

257

[Steroids and lipids from Spirodela polyrrhiza].  

PubMed

Two steroids and two lipids were isolated from the ethanolic extract of Spirodela polyrrhiza. Their structures were identified by spectral analysis and chemical evidence, which were identified as stigmasterol, monopalmitic glycerate, daucosterol and palmitic acid. Monopalmitic glycerate was discovered from this plant for the first time. PMID:12569820

Ling, Y; Wan, F; Zheng, J

1998-11-01

258

Lipids status in human breast cyst fluids  

Microsoft Academic Search

Benign mammary gross cystic disease is the most common breast lesion; women with apocrine changes of epithelium lining the cysts are at higher risk for developing breast cancer than the normal population. Total cholesterol, high- and low-density lipoproteins fractions, triglycerides and phospholipids, lipase activity and total lipid concentrations were measured in cyst fluids and sera from 89 women affected by

F. Mannello; G. D. Bocchiotti; F. Pignatti Morano; L. M. Fratepietro; G. Gazzanelli

1996-01-01

259

Lipid Metabolism in Astacus astacus (L.)  

Microsoft Academic Search

ALTHOUGH not all vertebrate classes have been examined with regard to lipid metabolism, it has been established that vertebrates are able to synthesize cholesterol from acetate by way of squalene. Sometimes this phenomenon has been generalized for invertebrates. However, this view has proved to be incorrect. A wide variety of insects have been found to require cholesterol as an indispensable

D. I. Zandee

1962-01-01

260

Children's Health is Insulin and Lipid Dependant  

Microsoft Academic Search

To assess the differences in fasting blood glucose, insulin and lipids of children having family history of diabetes or heart disease in first or second degree relative compared with a control group. Questionnaire was given to collect demographic data and to assess the dietary habits and family history of these children. Demographic data, anthropometric measurements and blood samples for fasting

M. Z. I. Hydrie; A. Basif; R. Hakeem; M. Y. Ahmadani; Qamar Masood

261

Lipid bilayer arrays: cyclically formed and measured.  

PubMed

Artificial lipid bilayers have many uses. They are well established for scientific studies of reconstituted ion channels, used to host engineered pore proteins for sensing, and can potentially be applied in DNA sequencing. Droplet bilayers have significant technological potential for enabling many of these applications due to their compatibility with automation and array platforms. To further develop this potential, we have simplified the formation and electrical measurement of droplet bilayers using an apparatus that only requires fluid dispensation. We achieved simultaneous bilayer formation and measurement over a 32-element array with ~80% yield and no operator input following fluid addition. Cycling these arrays resulted in the formation and measurement of 96 out of 120 possible bilayers in 80 minutes, a sustainable rate that could significantly increase with automation and greater parallelization. This turn-key, high-yield approach to making artificial lipid bilayers requires no training, making the capability of creating and measuring lipid bilayers and ion channels accessible to a much wider audience. In addition, this approach is low-cost, parallelizable, and automatable, allowing high-throughput studies of ion channels and pore proteins in lipid bilayers for sensing or screening applications. PMID:24730059

Lu, Bin; Kocharyan, Gayane; Schmidt, Jacob J

2014-03-01

262

Lipid Transfer Proteins and Allergy to Oranges  

Microsoft Academic Search

Background: Lipid transfer proteins (LTPs) are relevant fruit allergens, recently proposed as model plant food allergens. No citrus fruit allergen has been characterized to date. We sought to identify and isolate citrus fruit LTPs and to explore their relevance in orange allergy. Methods: Twenty-seven patients, showing mainly oral allergy syndrome after orange ingestion, as well as positive prick responses and

Oussama Ahrazem; M. Dolores Ibáñez; Gema López-Torrejón; Rosa Sánchez-Monge; Joaquin Sastre; Manuel Lombardero; Domingo Barber; Gabriel Salcedo

2005-01-01

263

ATF4 regulates lipid metabolism and thermogenesis.  

PubMed

Activating transcription factor 4 (ATF4) has been shown to play key roles in many physiological processes. There are no reports, however, demonstrating a direct link between ATF4 and lipid metabolism. We noticed that Atf4-deficient mice are lean, suggesting a possible role for ATF4 in regulating lipid metabolism. The goal of our current study is to investigate the involvement of ATF4 in lipid metabolism and elucidate the underlying mechanisms. Studies using Atf4-deficient mice revealed increased energy expenditure, as measured by oxygen consumption. These mice also showed increases in lipolysis, expression of uncoupling protein 2 (UCP2) and beta-oxidation genes and decreases in expression of lipogenic genes in white adipose tissue (WAT), suggesting increased utilization and decreased synthesis of fatty acids, respectively. Expression of UCP1, 2 and 3 was also increased in brown adipose tissue (BAT), suggesting increased thermogenesis. The effect of ATF4 deletion on expression of UCPs in BAT suggests that increased thermogenesis may underlie increased energy expenditure. Thus, our study identifies a possible new function for ATF4 in regulating lipid metabolism and thermogenesis. PMID:20066008

Wang, Chunxia; Huang, Zhiying; Du, Ying; Cheng, Ying; Chen, Shanghai; Guo, Feifan

2010-02-01

264

Serum lipids and cardiovascular reactivity to stress  

Microsoft Academic Search

Several studies have reported an association between serum lipid levels and cardiovascular reactivity to laboratory stressors. Their findings, however, are equivocal. The inconsistencies may be due to shortcomings such as the small number of subjects, the inclusion of patient groups, no control for medication, and no control for age effects. Two studies are presented investigating the relationship in large groups

Lorenz J. P. van Doornen; Harold Snieder; Dorret I. Boomsma

1998-01-01

265

The attractive forces between polar lipid bilayers.  

PubMed Central

Long-range attractive forces between lipid bilayers are not well described by the Lifshitz theory of Van der Waals forces between macroscopic media. It is shown that when correlations between polar headgroups are taken into account, the predicted forces take a qualitatively different form consistent with the measured data. PMID:3349135

Attard, P; Mitchell, D J; Ninham, B W

1988-01-01

266

Lipid rafts: bringing order to chaos  

Microsoft Academic Search

Lipid rafts are subdomains of the plasma mem- brane that contain high concentrations of cholesterol and glycosphingolipids. They exist as distinct liquid-ordered re- gions of the membrane that are resistant to extraction with nonionic detergents. Rafts appear to be small in size, but may constitute a relatively large fraction of the plasma membrane. While rafts have a distinctive protein and

Linda J. Pike

2003-01-01

267

Engineering Lipid Bilayer Membranes for Protein Studies  

PubMed Central

Lipid membranes regulate the flow of nutrients and communication signaling between cells and protect the sub-cellular structures. Recent attempts to fabricate artificial systems using nanostructures that mimic the physiological properties of natural lipid bilayer membranes (LBM) fused with transmembrane proteins have helped demonstrate the importance of temperature, pH, ionic strength, adsorption behavior, conformational reorientation and surface density in cellular membranes which all affect the incorporation of proteins on solid surfaces. Much of this work is performed on artificial templates made of polymer sponges or porous materials based on alumina, mica, and porous silicon (PSi) surfaces. For example, porous silicon materials have high biocompatibility, biodegradability, and photoluminescence, which allow them to be used both as a support structure for lipid bilayers or a template to measure the electrochemical functionality of living cells grown over the surface as in vivo. The variety of these media, coupled with the complex physiological conditions present in living systems, warrant a summary and prospectus detailing which artificial systems provide the most promise for different biological conditions. This study summarizes the use of electrochemical impedance spectroscopy (EIS) data on artificial biological membranes that are closely matched with previously published biological systems using both black lipid membrane and patch clamp techniques. PMID:24185908

Khan, Muhammad Shuja; Dosoky, Noura Sayed; Williams, John Dalton

2013-01-01

268

Role of cholesterol and lipid organization in disease  

NASA Astrophysics Data System (ADS)

Membrane lipids are essential for biological functions ranging from membrane trafficking to signal transduction. The composition of lipid membranes influences their organization and properties, so it is not surprising that disorders in lipid metabolism and transport have a role in human disease. Significant recent progress has enhanced our understanding of the molecular and cellular basis of lipid-associated disorders such as Tangier disease, Niemann-Pick disease type C and atherosclerosis. These insights have also led to improved understanding of normal physiology.

Maxfield, Frederick R.; Tabas, Ira

2005-12-01

269

Molecular driving forces defining lipid positions around aquaporin-0.  

PubMed

Lipid-protein interactions play pivotal roles in biological membranes. Electron crystallographic studies of the lens-specific water channel aquaporin-0 (AQP0) revealed atomistic views of such interactions, by providing high-resolution structures of annular lipids surrounding AQP0. It remained unclear, however, whether these lipid structures are representative of the positions of unconstrained lipids surrounding an individual protein, and what molecular determinants define the lipid positions around AQP0. We addressed these questions by using molecular dynamics simulations and crystallographic refinement, and calculated time-averaged densities of dimyristoyl-phosphatidylcholine lipids around AQP0. Our simulations demonstrate that, although the experimentally determined crystallographic lipid positions are constrained by the crystal packing, they appropriately describe the behavior of unconstrained lipids around an individual AQP0 tetramer, and thus likely represent physiologically relevant lipid positions.While the acyl chains were well localized, the lipid head groups were not. Furthermore, in silico mutations showed that electrostatic interactions do not play a major role attracting these phospholipids towards AQP0. Instead, the mobility of the protein crucially modulates the lipid localization and explains the difference in lipid density between extracellular and cytoplasmic leaflets. Moreover, our simulations support a general mechanism in which membrane proteins laterally diffuse accompanied by several layers of localized lipids, with the positions of the annular lipids being influenced the most by the protein surface. We conclude that the acyl chains rather than the head groups define the positions of dimyristoyl-phosphatidylcholine lipids around AQP0. Lipid localization is largely determined by the mobility of the protein surface, whereas hydrogen bonds play an important but secondary role. PMID:22679286

Aponte-Santamaría, Camilo; Briones, Rodolfo; Schenk, Andreas D; Walz, Thomas; de Groot, Bert L

2012-06-19

270

Lipid composition of mangrove and its relevance to salt tolerance  

Microsoft Academic Search

  \\u000a Lipid compositions of mangrove trees were studied in relation to the salt-tolerance mechanism. Leaves and roots were obtained\\u000a from seven mature mangrove trees on Iriomote Island, Okinawa: Bruguiera gymnorrhiza, Rhizophora stylosa, Kandelia candel, Lumnitzera racemosa, Avicennia marina, Pemphis acidula and Sonneratia alba. Lipids of mangrove leaves mainly consisted of 11 lipid classes: polar lipids, unknown (UK) 1–6, sterols, triacyl

Hirosuke Oku; Shigeyuki Baba; Hiroya Koga; Kensaku Takara; Hironori Iwasaki

2003-01-01

271

Lipid-based colloidal carriers for peptide and protein delivery – liposomes versus lipid nanoparticles  

PubMed Central

This paper highlights the importance of lipid-based colloidal carriers and their pharmaceutical implications in the delivery of peptides and proteins for oral and parenteral administration. There are several examples of biomacromolecules used nowadays in the therapeutics, which are promising candidates to be delivered by means of liposomes and lipid nanoparticles, such as solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC). Several production procedures can be applied to achieve a high association efficiency between the bioactives and the carrier, depending on the physicochemical properties of both, as well as on the production procedure applied. Generally, this can lead to improved bioavailability, or in case of oral administration a more consistent temporal profile of absorption from the gastrointestinal tract. Advantages and drawbacks of such colloidal carriers are also pointed out. This article describes strategies used for formulation of peptides and proteins, methods used for assessment of association efficiency and practical considerations regarding the toxicological concerns. PMID:18203427

Martins, Susana; Sarmento, Bruno; Ferreira, Domingos C; Souto, Eliana B

2007-01-01

272

REGULATION OF LIPID METABOLISM AND MILK LIPID CONTENT IN NORTHERN ELEPHANT SEALS  

E-print Network

that the regulation of the release of precursors on the sideregulation due to the additional demand for milk lipid precursorsprecursors stored in the body. The goal of this study was to investigate the regulation

Fowler, Melinda Anne

2012-01-01

273

Protein/Lipid Coaggregates are Formed During ?-Synuclein-Induced Disruption of Lipid Bilayers.  

PubMed

Amyloid formation is associated with neurodegenerative diseases such as Parkinson's disease (PD). Significant ?-synuclein (?SN) deposition in lipid-rich Lewy bodies is a hallmark of PD. Nonetheless, an unraveling of the connection between neurodegeneration and amyloid fibrils, including the molecular mechanisms behind potential amyloid-mediated toxic effects, is still missing. Interaction between amyloid aggregates and the lipid cell membrane is expected to play a key role in the disease progress. Here, we present experimental data based on hybrid analysis of two-photon-microscopy, solution small-angle X-ray scattering and circular dichroism data. Data show in real time changes in liposome morphology and stability upon protein addition and reveal that membrane disruption mediated by amyloidogenic ?SN is associated with dehydration of anionic lipid membranes and stimulation of protein secondary structure. As a result of membrane fragmentation, soluble ?SN:-lipid coaggregates are formed, hence, suggesting a novel molecular mechanism behind PD amyloid cytotoxicity. PMID:25210839

van Maarschalkerweerd, Andreas; Vetri, Valeria; Langkilde, Annette Eva; Foderà, Vito; Vestergaard, Bente

2014-10-13

274

Role of cholesterol in lipid raft formation: lessons from lipid model systems  

Microsoft Academic Search

Biochemical and cell-biological experiments have identified cholesterol as an important component of lipid ‘rafts’ and related structures (e.g., caveolae) in mammalian cell membranes, and membrane cholesterol levels as a key factor in determining raft stability and organization. Studies using cholesterol-containing bilayers as model systems have provided important insights into the roles that cholesterol plays in determining lipid raft behavior. This

John R. Silvius

2003-01-01

275

Lipid peroxidation of IV lipid emulsions in TPN bags: The influence of tocopherols  

Microsoft Academic Search

Four commercial IV lipid emulsions containing soybean oil were investigated to determine the tocopherol content. A sensitive high-performance liquid chromatography (HPLC) on a diol column was established to quantitate the tocopherol isomers in lipid emulsions. A previously described iodometric titration was used to assess the peroxide value (mmol peroxides\\/L). The pH was measured also. The initial tocopherol concentration ranges in

Patrick J. K. Steger; Stefan F. Mühlebach

1998-01-01

276

Permeability and electrical properties of planar lipid membranes from thylakoid lipids.  

PubMed Central

Electrical measurements were carried out on planar lipid membranes from thylakoid lipids. The specific capacitance of membranes formed from decane-containing monogalactosyldiacylglycerol (MGDG), which accounts for 57% of the total lipid content of thylakoids, showed that it adopted a bilayer structure. Solvent-free bilayers of MGDG were not formed, with very rare exceptions, indicating that decane is required to stabilize the planar conformation. However, this cone-shaped lipid produces bilayer structures in combination with other cylindrical thylakoid lipids even in the absence of organic solvent. We compared the properties of solvent-free and decane-containing bilayers from MGDG, soybean lecithin, and the quaternary mixture of lipids similar to that found in vivo. The conductance of decane-MGDG was 26 times higher than that of decane-lecithin. The flux through the decane-lecithin bilayer was found to be slightly dependent on pH, whereas the decane-MGDG membrane was not. The specific conductance of bilayers formed from the quaternary mixture of lipids was 5 to 10 times larger than lecithin (with alkane or not). Further experiments with bilayers made in the presence of a KCl gradient showed that decane-MGDG, decane-MGDG/DGDG/SQDG/PG, and solvent-free MGDG/DGDG/SQDG/PG were cation-selective. The permeability coefficient for potassium ranged from 4.9 to 8.3 x 10(-11) cm s-1. The permeability coefficient for protons in galactolipids, however, was determined to be about six orders of magnitude higher than the value for potassium ions. The HCl permeation mechanism through the lipid membranes was determined from diffusion potentials measured in HCl gradients. Our results suggest that HCl was not transported as neutral molecules. The data is discussed with regard to the function of galactolipids in the ion transport through thylakoid membranes. PMID:8061192

Fuks, B; Homble, F

1994-01-01

277

LipidBlast - in-silico tandem mass spectrometry database for lipid identification  

PubMed Central

Current tandem mass spectral libraries for lipid annotations in metabolomics are limited in size and diversity. We provide a freely available computer generated in-silico tandem mass spectral library of 212,516 MS/MS spectra covering 119,200 compounds from 26 lipid compound classes, including phospholipids, glycerolipids, bacterial lipoglycans and plant glycolipids. Platform independence is shown by using tandem mass spectra from 40 different mass spectrometer types including low-resolution and high-resolution instruments. PMID:23817071

Kind, Tobias; Liu, Kwang-Hyeon; Yup Lee, Do; DeFelice, Brian; Meissen, John K.; Fiehn, Oliver

2013-01-01

278

A Teaching Laboratory for Comprehensive Lipid Characterization from Food Samples  

ERIC Educational Resources Information Center

Traditional and state-of-the-art techniques were combined to probe for various lipid classes from egg yolk and avocado qualitatively and quantitatively. A total lipid extract was isolated using liquid-liquid extraction. An aliquot of the total lipid extract was subjected to transesterification to form volatile fatty acid methyl esters suitable for…

Bendinskas, Kestutis; Weber, Benjamin; Nsouli, Tamara; Nguyen, Hoangvy V.; Joyce, Carolyn; Niri, Vadoud; Jaskolla, Thorsten W.

2014-01-01

279

Rapid, colorimetric quantification of lipid from algal cultures  

Microsoft Academic Search

Algae have significant potential as a source of biomass for the production of biofuels, due to their high growth rates and high cellular lipid content. Studies that address the use of algae as biofuels often require the frequent measurement of algal lipid content. Traditional methods for the quantification of lipid are, however, costly if sub-contracted, or involve the use of

Boris Wawrik; Brian H. Harriman

2010-01-01

280

Final Report: 17th international Symposium on Plant Lipids  

SciTech Connect

This meeting covered several emerging areas in the plant lipid field such as the biosynthesis of cuticle components, interorganelle lipid trafficking, the regulation of lipid homeostasis, and the utilization of algal models. Stimulating new insights were provided not only based on research reports based on plant models, but also due to several excellent talks by experts from the yeast field.

Christoph Benning

2007-03-07

281

Ordered Nanoclusters in Lipid-Cholesterol Membranes Maria K. Ratajczak  

E-print Network

Ordered Nanoclusters in Lipid-Cholesterol Membranes Maria K. Ratajczak Department of Physics comprising the plasma membrane are inhomogeneously distributed, form- ing liquid domains rich in cholesterol and the role cholesterol plays on mem- brane lipid organization remain unresolved. Characteriza- tion of lipid

Lee, Ka Yee C.

282

Human stratum corneum lipids: characterization and regional variations  

Microsoft Academic Search

The lipids of mammalian stratum corneum are known to be important regulators of skin permeability. Since the human stratum corneum displays remarkable regional variations in skin permeability, we assessed the total lipid con- centration, the distribution of all major lipid species, and the fatty acid composition in Bligh-Dyer extracts from four skin sites (abdomen, leg, face, and sole) that are

Marilyn A. Lampe; A. L. Burlingame; JoAnne Whitney; Mary L. Williams; Barbara E. Brown; Esther Roitman; Peter M. Elias

283

Dietary ethanol and lipid synthesis in Drosophila melanogaster  

Microsoft Academic Search

When cultured on a defined diet, ethanol was an efficient substrate for lipid synthesis in wild-type Drosophila melanogaster larvae. At certain dietary levels both ethanol and sucrose could displace the other as a lipid substrate. In wild-type larvae more than 90% of the flux from ethanol to lipid was metabolized via the alcohol dehydrogenase (ADH) system. The ADH and aldehyde

Billy W. Geer; Marilyn L. Langevin; Stephen W. McKechnie

1985-01-01

284

Lipids and lipophilic components of Viburnum opulus fruits during maturation  

Microsoft Academic Search

The variation of the composition of neutral and polar lipids and lipophilic components during maturation of guelder rose (V. opulus L., fam. Caprifoliaceae) fruits was investigated. During fruit ripening, all lipid groups are accumulated, the highest accumulation rate being observed in the first period of maturation. In nonpolar lipids, this is due to a substantial increase in the content of

A. R. Karimova; S. G. Yunusova; E. G. Galkin; N. I. Fedorov; M. S. Yunusov

2004-01-01

285

Two-Component Membrane Lithography via Lipid Backfilling  

E-print Network

natural lipid rafts[13] were patterned photolithographically into supported bilayers.[14] Our approachTwo-Component Membrane Lithography via Lipid Backfilling Seung-Yong Jung,[a] Matthew A. Holden lithographic technique to pattern artificial lipid bilayer microdomains by ex- ploiting the limited mobility

286

Fast molecular tracking maps nanoscale dynamics of plasma membrane lipids  

E-print Network

nano-organization. single molecule tracking membrane dynamics lipid rafts Many open questions into nanodomains, so-called "lipid rafts" (8­12). Since their proposal, the question of the existence), delivering subdiffraction resolution in live cells, provided direct evidence that certain lipids

Hell, Stefan W.

287

Lipid domains control myelin basic protein adsorption and membrane interactions between model myelin lipid bilayers.  

PubMed

The surface forces apparatus and atomic force microscope were used to study the effects of lipid composition and concentrations of myelin basic protein (MBP) on the structure of model lipid bilayers, as well as the interaction forces and adhesion between them. The lipid bilayers had a lipid composition characteristic of the cytoplasmic leaflets of myelin from "normal" (healthy) and "disease-like" [experimental allergic encephalomyelitis (EAE)] animals. They showed significant differences in the adsorption mechanism of MBP. MBP adsorbs on normal bilayers to form a compact film (3-4 nm) with strong intermembrane adhesion (?0.36 mJ/m(2)), in contrast to its formation of thicker (7-8 nm) swelled films with weaker intermembrane adhesion (?0.13 mJ/m(2)) on EAE bilayers. MBP preferentially adsorbs to liquid-disordered submicron domains within the lipid membranes, attributed to hydrophobic attractions. These results show a direct connection between the lipid composition of membranes and membrane-protein adsorption mechanisms that affects intermembrane spacing and adhesion and has direct implications for demyelinating diseases. PMID:24516125

Lee, Dong Woog; Banquy, Xavier; Kristiansen, Kai; Kaufman, Yair; Boggs, Joan M; Israelachvili, Jacob N

2014-02-25

288

Lipid domains control myelin basic protein adsorption and membrane interactions between model myelin lipid bilayers  

PubMed Central

The surface forces apparatus and atomic force microscope were used to study the effects of lipid composition and concentrations of myelin basic protein (MBP) on the structure of model lipid bilayers, as well as the interaction forces and adhesion between them. The lipid bilayers had a lipid composition characteristic of the cytoplasmic leaflets of myelin from “normal” (healthy) and “disease-like” [experimental allergic encephalomyelitis (EAE)] animals. They showed significant differences in the adsorption mechanism of MBP. MBP adsorbs on normal bilayers to form a compact film (3–4 nm) with strong intermembrane adhesion (?0.36 mJ/m2), in contrast to its formation of thicker (7–8 nm) swelled films with weaker intermembrane adhesion (?0.13 mJ/m2) on EAE bilayers. MBP preferentially adsorbs to liquid-disordered submicron domains within the lipid membranes, attributed to hydrophobic attractions. These results show a direct connection between the lipid composition of membranes and membrane–protein adsorption mechanisms that affects intermembrane spacing and adhesion and has direct implications for demyelinating diseases. PMID:24516125

Lee, Dong Woog; Banquy, Xavier; Kristiansen, Kai; Kaufman, Yair; Boggs, Joan M.; Israelachvili, Jacob N.

2014-01-01

289

Polymerized planar suspended lipid bilayers for single ion channel recordings: comparison of several dienoyl lipids.  

PubMed

The stabilization of suspended planar lipid membranes, or black lipid membranes (BLMs), through polymerization of mono- and bis-functionalized dienoyl lipids was investigated. Electrical properties, including capacitance, conductance, and dielectric breakdown voltage, were determined for BLMs composed of mono-DenPC, bis-DenPC, mono-SorbPC, and bis-SorbPC both prior to and following photopolymerization, with diphytanoyl phosphocholine (DPhPC) serving as a control. Poly(lipid) BLMs exhibited significantly longer lifetimes and increased the stability of air-water transfers. BLM stability followed the order bis-DenPC > mono-DenPC ? mono-SorbPC > bis-SorbPC. The conductance of bis-SorbPC BLMs was significantly higher than that of the other lipids, which is attributed to a high density of hydrophilic pores, resulting in relatively unstable membranes. The use of poly(lipid) BLMs as matrices for supporting the activity of an ion channel protein (IC) was explored using ?-hemolysin (?-HL), a model IC. Characteristic i-V plots of ?-HL were maintained following photopolymerization of bis-DenPC, mono-DenPC, and mono-SorbPC, demonstrating the utility of these materials for preparing more durable BLMs for single-channel recordings of reconstituted ICs. PMID:21226498

Heitz, Benjamin A; Xu, Juhua; Jones, Ian W; Keogh, John P; Comi, Troy J; Hall, Henry K; Aspinwall, Craig A; Saavedra, S Scott

2011-03-01

290

Adhesion and hemifusion of cytoplasmic myelin lipid membranes are highly dependent on the lipid composition  

PubMed Central

We report the effects of calcium ions on the adhesion and hemifusion mechanisms of model supported myelin lipid bilayer membranes of differing lipid composition. As in our previous studies [1, 2], the lipid compositions used mimic “healthy” and “diseased-like” (experimental autoimmune encephalomyelitis, EAE) membranes. Our results show that the interaction forces as a function of membrane separation distance are well described by a generic model that also (and in particular) includes the hydrophobic interaction arising from the hydrophobically exposed (interior) parts of the bilayers. The model is able to capture the mechanical instability that triggers the onset of the hemifusion event, and highlights the primary role of the hydrophobic interaction in membrane fusion. The effects of lipid composition on the fusion mechanism, and the adhesion forces between myelin lipid bilayers, can be summarized as follow: in calcium-free buffer, healthy membranes do not present any signs of adhesion or hemifusion, while diseased membranes hemifuse easily. Addition of 2 mM calcium favors adhesion and hemifusion of the membranes independently of their composition, but the mechanisms involved in the two processes were different: healthy bilayers systematically presented stronger adhesion forces and lower energy barriers to fusion compared to diseased bilayers. These results are of particular relevance for understanding lesion development (demyelination, swelling, vacuolization and/or vesiculation) in myelin associated diseases such as multiple sclerosis and its relationship to lipid domain formation in myelin membranes. PMID:22047743

Banquy, Xavier; Kristiansen, Kai; Lee, Dong Woog; Israelachvili, Jacob N.

2012-01-01

291

Cytoplasmic lipid droplet accumulation in developing mammary epithelial cells: roles of adipophilin and lipid metabolism.  

PubMed

PAT proteins (perilipin, adipophilin, and TIP47) are hypothesized to be critical regulators of lipid accumulation in eukaryotic cells. We investigated the developmental relationships between the expression of these proteins and cytoplasmic lipid droplet (CLD) accumulation in differentiating secretory epithelial cells in mouse mammary glands. Adipophilin (ADPH) specifically localized to CLD in differentiating and lactating mammary glands and was found exclusively in the secreted lipid droplet fraction of mouse milk. ADPH transcripts were selectively detected in secretory epithelial cells, and steady-state levels of both ADPH mRNA and protein increased during secretory differentiation in patterns consistent with functional linkage to CLD accumulation. TIP47 also was detected in secretory epithelial cells; however, it had a diffuse punctate appearance, and its mRNA and protein expression patterns did not correlate with CLD accumulation. Perilipin-positive adipose cells and steady-state levels of perilipin mRNA and protein decreased during mammary gland differentiation, suggesting a progressive loss of adipose lipid storage during this process. Collectively, these data demonstrate that increased ADPH expression is a specialized property of differentiated secretory epithelial cells and provide developmental evidence specifically linking increased ADPH expression to increased CLD accumulation. In addition, evidence is presented that the epithelial and adipose compartments of the mammary gland undergo concerted, developmentally regulated shifts in lipid metabolism that increase the availability of fatty acids necessary for lipid synthesis by milk-secreting cells. PMID:17452747

Russell, Tanya D; Palmer, Carol A; Orlicky, David J; Fischer, Andreas; Rudolph, Michael C; Neville, Margaret C; McManaman, James L

2007-07-01

292

Solid Lipid Nanoparticles of Guggul Lipid as Drug Carrier for Transdermal Drug Delivery  

PubMed Central

Diclofenac sodium loaded solid lipid nanoparticles (SLNs) were formulated using guggul lipid as major lipid component and analyzed for physical parameters, permeation profile, and anti-inflammatory activity. The SLNs were prepared using melt-emulsion sonication/low temperature-solidification method and characterized for physical parameters, in vitro drug release, and accelerated stability studies, and formulated into gel. Respective gels were compared with a commercial emulgel (CEG) and plain carbopol gel containing drug (CG) for ex vivo and in vivo drug permeation and anti-inflammatory activity. The SLNs were stable with optimum physical parameters. GMS nanoparticle 1 (GMN-1) and stearic acid nanoparticle 1 (SAN-1) gave the highest in vitro drug release. Guggul lipid nanoparticle gel 3 (GLNG-3) showed 104.68 times higher drug content than CEG in receptor fluid. The enhancement ratio of GLNG-3 was 39.43 with respect to CG. GLNG-3 showed almost 8.12 times higher Cmax than CEG at 4 hours. The AUC value of GLNG-3 was 15.28 times higher than the AUC of CEG. GLNG-3 showed edema inhibition up to 69.47% in the first hour. Physicochemical properties of major lipid component govern the properties of SLN. SLN made up of guggul lipid showed good physical properties with acceptable stability. Furthermore, it showed a controlled drug release profile along with a promising permeation profile. PMID:24058913

Gaur, Praveen Kumar; Mishra, Shikha; Purohit, Suresh

2013-01-01

293

Solid lipid nanoparticles of guggul lipid as drug carrier for transdermal drug delivery.  

PubMed

Diclofenac sodium loaded solid lipid nanoparticles (SLNs) were formulated using guggul lipid as major lipid component and analyzed for physical parameters, permeation profile, and anti-inflammatory activity. The SLNs were prepared using melt-emulsion sonication/low temperature-solidification method and characterized for physical parameters, in vitro drug release, and accelerated stability studies, and formulated into gel. Respective gels were compared with a commercial emulgel (CEG) and plain carbopol gel containing drug (CG) for ex vivo and in vivo drug permeation and anti-inflammatory activity. The SLNs were stable with optimum physical parameters. GMS nanoparticle 1 (GMN-1) and stearic acid nanoparticle 1 (SAN-1) gave the highest in vitro drug release. Guggul lipid nanoparticle gel 3 (GLNG-3) showed 104.68 times higher drug content than CEG in receptor fluid. The enhancement ratio of GLNG-3 was 39.43 with respect to CG. GLNG-3 showed almost 8.12 times higher C(max) than CEG at 4 hours. The AUC value of GLNG-3 was 15.28 times higher than the AUC of CEG. GLNG-3 showed edema inhibition up to 69.47% in the first hour. Physicochemical properties of major lipid component govern the properties of SLN. SLN made up of guggul lipid showed good physical properties with acceptable stability. Furthermore, it showed a controlled drug release profile along with a promising permeation profile. PMID:24058913

Gaur, Praveen Kumar; Mishra, Shikha; Purohit, Suresh

2013-01-01

294

Food intake and absorption are affected by dietary lipid level and lipid source in seabream ( Sparus aurata L.) larvae  

Microsoft Academic Search

Marine larval nutrition studies have classically focused on essential fatty acid (EFA) requirements and very little is known regarding the effect of total lipid level or lipid source on food ingestion and absorption, which are important factors determining growth. In the present work two experiments analysed food intake and nutrient absorption in seabream larvae in response to two dietary lipid

Sofia Morais; Michal Torten; Oryia Nixon; Sigal Lutzky; Luís E. C. Conceição; Maria Teresa Dinis; Amos Tandler; William Koven

2006-01-01

295

AMER. ZOOL., 38:268-279 (1998) The Role of Lipid Physical Properties in Lipid Barriers1  

E-print Network

AMER. ZOOL., 38:268-279 (1998) The Role of Lipid Physical Properties in Lipid Barriers1 ALLEN G biological molecules in that they are defined by their physical properties rather than by their chemical cases, physiological functions of lipids appear to depend upon their physical properties. The most well

Ahmad, Sajjad

296

Lipid Rafts Prepared by Different Methods Contain Different Connexin Channels, but Gap Junctions Are Not Lipid Rafts  

E-print Network

Lipid Rafts Prepared by Different Methods Contain Different Connexin Channels, but Gap Junctions Are Not Lipid Rafts Darren Locke,* Jade Liu, and Andrew L. Harris Department of Pharmacology and Physiology, MSB. These lipid "rafts" are implicated in protein sorting and are attractive candidates as platforms

Harris, Andrew L.

297

Quantitative proteomic analysis of B cell lipid rafts reveals that ezrin regulates antigen receptor–mediated lipid raft dynamics  

Microsoft Academic Search

Ligation of the B cell antigen receptor (BCR) with antigen induces lipid raft coalescence, a process that occurs after crosslinking of a variety of signaling receptors and is thought to potentiate cellular activation. To investigate lipid raft dynamics during BCR signaling, we quantitatively analyzed the B cell lipid raft proteome. BCR engagement induced dissociation of the adaptor protein ezrin from

Neetu Gupta; Bernd Wollscheid; Julian D Watts; Barbara Scheer; Ruedi Aebersold; Anthony L DeFranco

2006-01-01

298

Epidermal Growth Factor Receptors Are Localized to Lipid Rafts That Contain a Balance of Inner and Outer Leaflet Lipids  

E-print Network

interest has been the finding that many molecules involved in cell signaling are enriched in lipid raftsEpidermal Growth Factor Receptors Are Localized to Lipid Rafts That Contain a Balance of Inner 63110 The epidermal growth factor (EGF) receptor parti- tions into lipid rafts made using a detergent

Pike, Linda J.

299

Lipid Composition of Growing and Starving Cells of Arthrobacter crystallopoietes  

PubMed Central

The lipid composition of growing and starving cells of Arthrobacter crystallopoietes was compared. Although the lipid composition of the two cell types was similar, the amount of total lipids recovered from the starving cells was 30.4% less than that recovered from the growing cells. The loss of lipids, as compared to the loss of total cell mass during starvation, was (i) proportional to the loss of the cell mass (phosphatidylinositol, phosphatidylglycerol-2, and cardiolipin), (ii) greater than the loss in cell mass (neutral lipids, “glycophospholipids,” and phosphatidic acid), or (iii) less than the loss in cell mass (coenzyme Q, glycolipids, and phosphatidylglycerol-1). PMID:4669211

Kostiw, Luba L.; Boylen, C. W.; Tyson, B. J.

1972-01-01

300

Lipid raft: A floating island of death or survival  

SciTech Connect

Lipid rafts are microdomains of the plasma membrane enriched in cholesterol and sphingolipids, and play an important role in the initiation of many pharmacological agent-induced signaling pathways and toxicological effects. The structure of lipid rafts is dynamic, resulting in an ever-changing content of both lipids and proteins. Cholesterol, as a major component of lipid rafts, is critical for the formation and configuration of lipid raft microdomains, which provide signaling platforms capable of activating both pro-apoptotic and anti-apoptotic signaling pathways. A change of cholesterol level can result in lipid raft disruption and activate or deactivate raft-associated proteins, such as death receptor proteins, protein kinases, and calcium channels. Several anti-cancer drugs are able to suppress growth and induce apoptosis of tumor cells through alteration of lipid raft contents via disrupting lipid raft integrity. -- Highlights: ? The role of lipid rafts in apoptosis ? The pro- and anti-apoptotic effects of lipid raft disruption ? Cancer treatments targeting lipid rafts.

George, Kimberly S. [Edison Biotechnology Institute and Department of Chemistry and Biochemistry, Ohio University, Athens, Ohio 45701 (United States) [Edison Biotechnology Institute and Department of Chemistry and Biochemistry, Ohio University, Athens, Ohio 45701 (United States); Department of Chemistry, Marietta College, Marietta, OH 45750 (United States); Wu, Shiyong, E-mail: wus1@ohio.edu [Edison Biotechnology Institute and Department of Chemistry and Biochemistry, Ohio University, Athens, Ohio 45701 (United States)] [Edison Biotechnology Institute and Department of Chemistry and Biochemistry, Ohio University, Athens, Ohio 45701 (United States)

2012-03-15

301

Lipid lowering in liver and chronic kidney disease.  

PubMed

Lipid lowering, particularly with HMG CoA reductase inhibitors ("statins"), reduces the risk of cardiovascular disease. Patients with chronic liver and kidney disease present challenges to the use of lipid medications. In the case of most liver disorders, the concern has been one of safety. There is evidence that most lipid-lowering medications can be used safely in many situations, although large outcomes trials are not available. In contrast, in chronic kidney disease, dosing of lipid medications may require substantial modification depending on creatinine clearance. There are significant alterations in lipid metabolism in chronic kidney disease with concomitant increases in cardiovascular risk. Some data are available on cardiovascular outcomes with dyslipidemia treatment in renal patients. This review will examine lipid physiology and cardiovascular risk in specific liver and kidney diseases and review the evidence for lipid lowering and the use of statin and non-statin therapies in chronic liver and kidney disease. PMID:24840263

Herrick, Cynthia; Litvin, Marina; Goldberg, Anne Carol

2014-06-01

302

Lipids in cell biology: how can we understand them better?  

PubMed Central

Lipids are a major class of biological molecules and play many key roles in different processes. The diversity of lipids is on the same order of magnitude as that of proteins: cells express tens of thousands of different lipids and hundreds of proteins to regulate their metabolism and transport. Despite their clear importance and essential functions, lipids have not been as well studied as proteins. We discuss here some of the reasons why it has been challenging to study lipids and outline technological developments that are allowing us to begin lifting lipids out of their “Cinderella” status. We focus on recent advances in lipid identification, visualization, and investigation of their biophysics and perturbations and suggest that the field has sufficiently advanced to encourage broader investigation into these intriguing molecules. PMID:24925915

Muro, Eleonora; Atilla-Gokcumen, G. Ekin; Eggert, Ulrike S.

2014-01-01

303

Lipids in cell biology: how can we understand them better?  

PubMed

Lipids are a major class of biological molecules and play many key roles in different processes. The diversity of lipids is on the same order of magnitude as that of proteins: cells express tens of thousands of different lipids and hundreds of proteins to regulate their metabolism and transport. Despite their clear importance and essential functions, lipids have not been as well studied as proteins. We discuss here some of the reasons why it has been challenging to study lipids and outline technological developments that are allowing us to begin lifting lipids out of their "Cinderella" status. We focus on recent advances in lipid identification, visualization, and investigation of their biophysics and perturbations and suggest that the field has sufficiently advanced to encourage broader investigation into these intriguing molecules. PMID:24925915

Muro, Eleonora; Atilla-Gokcumen, G Ekin; Eggert, Ulrike S

2014-06-15

304

Control of lipid metabolism by tachykinin in Drosophila.  

PubMed

The intestine is a key organ for lipid uptake and distribution, and abnormal intestinal lipid metabolism is associated with obesity and hyperlipidemia. Although multiple regulatory gut hormones secreted from enteroendocrine cells (EEs) regulate systemic lipid homeostasis, such as appetite control and energy balance in adipose tissue, their respective roles regarding lipid metabolism in the intestine are not well understood. We demonstrate that tachykinins (TKs), one of the most abundant secreted peptides expressed in midgut EEs, regulate intestinal lipid production and subsequently control systemic lipid homeostasis in Drosophila and that TKs repress lipogenesis in enterocytes (ECs) associated with TKR99D receptor and protein kinase A (PKA) signaling. Interestingly, nutrient deprivation enhances the production of TKs in the midgut. Finally, unlike the physiological roles of TKs produced from the brain, gut-derived TKs do not affect behavior, thus demonstrating that gut TK hormones specifically regulate intestinal lipid metabolism without affecting neuronal functions. PMID:25263556

Song, Wei; Veenstra, Jan A; Perrimon, Norbert

2014-10-01

305

Anisotropic spontaneous curvatures in lipid membranes.  

PubMed

Symmetry restrictions due to fluidity require the strain energy in the Helfrich theory of lipid membranes to be locally isotropic in nature. Although this framework is suitable for modeling the interaction of membranes with proteins that generate spherical curvature such as clathrin, there are other important membrane-bending proteins such as BIN-amphiphysin-Rvs proteins that form a cylindrical coat with different curvatures in the longitudinal and the circumferential directions. In this work, we present a detailed mathematical treatment of the theory of lipid membranes incorporating anisotropic spontaneous curvatures. We derive the associated Euler-Lagrange equations and the edge conditions in a generalized setting that allows spatial heterogeneities in the properties of the membrane-protein system. We employ this theory to model the constriction of a membrane tubule by a cylindrical scaffold. In particular, we highlight the role of the equilibrium equation in the tangential plane in regulating the spatial variation of the surface tension field. PMID:25019822

Walani, Nikhil; Torres, Jennifer; Agrawal, Ashutosh

2014-06-01

306

Micropatterning fluid lipid bilayers on solid supports.  

PubMed

Lithographically patterned grids of photoresist, aluminum oxide, or gold on oxidized silicon substrates were used to partition supported lipid bilayers into micrometer-scale arrays of isolated fluid membrane corrals. Fluorescently labeled lipids were observed to diffuse freely within each membrane corral but were confined by the micropatterned barriers. The concentrations of fluorescent probe molecules in individual corrals were altered by selective photobleaching to create arrays of fluid membrane patches with differing compositions. Application of an electric field parallel to the surface induced steady-state concentration gradients of charged membrane components in the corrals. In addition to producing patches of membrane with continuously varying composition, these gradients provide an intrinsically parallel means of acquiring information about molecular properties such as the diffusion coefficient in individual corrals. PMID:9005848

Groves, J T; Ulman, N; Boxer, S G

1997-01-31

307

Membrane lipids and the origin of life  

NASA Technical Reports Server (NTRS)

The current state of knowledge regarding the development of biological systems is briefly reviewed. At a crucial stage concerning the evolution of such systems, the mechanisms leading to more complex structures must have evolved within the confines of a protected microenvironment, similar to those provided by the contemporary cell membranes. The major components found normally in biomembranes are phospholipids. The structure of the biomembrane is examined, and attention is given to questions concerning the availability of the structural components which are necessary in the formation of primitive lipid membranes. Two approaches regarding the study of protomembranes are discussed. The probability of obtaining ether lipids under prebiotic conditions is considered, taking into account the formation of cyclic and acyclic isoprenoids by the irradiation of isoprene with UV.

Oro, J.; Holzer, G.; Rao, M.; Tornabene, T. G.

1981-01-01

308

Retroviral matrix and lipids, the intimate interaction  

PubMed Central

Retroviruses are enveloped viruses that assemble on the inner leaflet of cellular membranes. Improving biophysical techniques has recently unveiled many molecular aspects of the interaction between the retroviral structural protein Gag and the cellular membrane lipids. This interaction is driven by the N-terminal matrix domain of the protein, which probably undergoes important structural modifications during this process, and could induce membrane lipid distribution changes as well. This review aims at describing the molecular events occurring during MA-membrane interaction, and pointing out their consequences in terms of viral assembly. The striking conservation of the matrix membrane binding mode among retroviruses indicates that this particular step is most probably a relevant target for antiviral research. PMID:21385335

2011-01-01

309

Urinary lipid bodies in polycystic kidney disease.  

PubMed

Urinary doubly refractile lipid bodies (oval fat bodies) are observed most frequently in patients with heavy proteinuria resulting from glomerular disease. We observed doubly refractile lipid bodies (DRLB) in the urine sediment of 60% of 35 patients with autosomal dominant polycystic kidney disease (ADPKD). All patients had clinical courses typical of ADPKD, and none exhibited the features of a second, unrelated renal disease. DRLB in the urine were correlated with a urine dipstick protein reading exceeding trace. Age, sex, BP, and serum creatinine concentration were not associated with the presence of DRLB in the urine. Examination of cyst fluid obtained from kidneys of six ADPKD patients revealed DRLB in 80% of cyst fluid samples that contained degraded blood (so-called chocolate cysts). The DRLB in cyst fluid were morphologically indistinguishable from those observed in urine, and DRLB from both sources were stained with oil red O. We conclude that urinary DRLB are a clinical feature of ADPKD. PMID:3966470

Duncan, K A; Cuppage, F E; Grantham, J J

1985-01-01

310

Hot-melt coating with lipid excipients.  

PubMed

Polymer coatings are widely used to provide drug protection, taste masking, coloration and modified drug release. Typically, coating polymers must be diluted or dispersed in solvents (water or organic) prior to coating and gliding agents are commonly added to prevent particle sticking throughout processing. Lipid excipients present an attractive alternative to standard polymer coatings as they only require melting before application directly onto the substrate. Solvent evaporation is not required; consequently powders with very high specific surface areas can be coated rapidly. A number of different lipid excipients can be used in coating and choosing the appropriate excipient for the application requires an understanding of their physico-chemical properties and its associated effect on drug release. PMID:23089578

Jannin, Vincent; Cuppok, Yvonne

2013-12-01

311

Low abundances of synthetics lipids in phantoms  

NASA Astrophysics Data System (ADS)

Phantoms simulate optical characteristics of tissues. Phantoms use to mimic light distributions in living tissue. Several Phantoms compositions made of silicone, polyester, polyurethane, and epoxy resin have been described in the literature. These kinds of phantoms have the problem of long time preservation. In this work, we describe the fabrication and characterization of phantoms with low concentrations of synthetic lipid using Raman spectroscopy. We fabricate four phantoms made of Polydimethylsiloxane (PDMS). These phantoms have synthetic lipid content of cholesterol and triglycerides. The size of our phantoms is 1 x 1 cm and 5 mm of thickness.We used the point-to-point mapping technique. Finally, we compared advantages and performance of made PDMS and gelatin phantoms.

Villanueva-Luna, A. E.; Santiago-Alvarado, A.; Castro-Ramos, J.; Vazquez-Montiel, S.; Flores-Gil, A.; Aguilar-Soto, J.; Delgado-Atencio, J. A.

2012-03-01

312

Shape optimization in lipid nanotube networks  

NASA Astrophysics Data System (ADS)

Starting from a high surface free-energy state, lipid nanotube networks are capable to self-organize into tree-like structures with particular geometrical features. In this work we analyze the process of self-organization in such networks, and report a strong similarity to the Euclidian Steiner Tree Problem (ESTP). ESTP is a well-known NP-hard optimization problem of finding a network connecting a given set of terminal points on a plane, allowing addition of auxiliary points, with the overall objective to minimize the total network length. The present study shows that aggregate lipid structures self-organize into geometries that correspond to locally optimal solutions to such problems.

Lobovkina, T.; Dommersnes, P. G.; Tiourine, S.; Joanny, J.-F.; Orwar, O.

2008-07-01

313

Shape optimization in lipid nanotube networks.  

PubMed

Starting from a high surface free-energy state, lipid nanotube networks are capable to self-organize into tree-like structures with particular geometrical features. In this work we analyze the process of self-organization in such networks, and report a strong similarity to the Euclidian Steiner Tree Problem (ESTP). ESTP is a well-known NP-hard optimization problem of finding a network connecting a given set of terminal points on a plane, allowing addition of auxiliary points, with the overall objective to minimize the total network length. The present study shows that aggregate lipid structures self-organize into geometries that correspond to locally optimal solutions to such problems. PMID:18500443

Lobovkina, T; Dommersnes, P G; Tiourine, S; Joanny, J-F; Orwar, O

2008-07-01

314

The Lipid A from Vibrio fischeri Lipopolysaccharide  

PubMed Central

Vibrio fischeri, a bioluminescent marine bacterium, exists in an exclusive symbiotic relationship with the Hawaiian bobtail squid, Euprymna scolopes, whose light organ it colonizes. Previously, it has been shown that the lipopolysaccharide (LPS) or free lipid A of V. fischeri can trigger morphological changes in the juvenile squid's light organ that occur upon colonization. To investigate the structural features that might be responsible for this phenomenon, the lipid A from V. fischeri ES114 LPS was isolated and characterized by multistage mass spectrometry (MSn). A microheterogeneous mixture of mono- and diphosphorylated diglucosamine disaccharides was observed with variable states of acylation ranging from tetra- to octaacylated forms. All lipid A species, however, contained a set of conserved primary acyl chains consisting of an N-linked C14:0(3-OH) at the 2-position, an unusual N-linked C14:1(3-OH) at the 2?-position, and two O-linked C12:0(3-OH) fatty acids at the 3- and 3?-positions. The fatty acids found in secondary acylation were considerably more variable, with either a C12:0 or C16:1 at the 2-position, C14:0 or C14:0(3-OH) at the 2?-position, and C12:0 or no substituent at the 3?-position. Most surprising was the presence of an unusual set of modifications at the secondary acylation site of the 3-position consisting of phosphoglycerol (GroP), lysophosphatidic acid (GroP bearing C12:0, C16:0, or C16:1), or phosphatidic acid (GroP bearing either C16:0 + C12:0 or C16:0 + C16:1). Given their unusual nature, it is possible that these features of the V. fischeri lipid A may underlie the ability of E. scolopes to recognize its symbiotic partner. PMID:21498521

Phillips, Nancy J.; Adin, Dawn M.; Stabb, Eric V.; McFall-Ngai, Margaret J.; Apicella, Michael A.; Gibson, Bradford W.

2011-01-01

315

Lipid modulation of neuronal cholinergic activity  

SciTech Connect

Phospholipids are the major lipids in the plasma membrane, and it is now evident that the function of phospholipids exceeds that of the role of barrier between different aqueous compartments. Several lines of evidence suggest that a major plasma membrane lipids, phosphatidylcholine, may be a useful compound for modulating presynaptic cholinergic transmission. In order to investigate the effects of PC on cholinergic terminals, rat cortical synaptosomes were preloaded with (/sup 3/H)-ACh and then treated with small unilamellar vesicles (SUV) composed of dipalmitoylphosphatidylcholine (DPPC) at concentrations (0.8-1.5 mg/ml) similar to those found circulating in plasma. The effects of DPPC on levels, hydrolysis, release, and synthesis of (/sup 3/H)-ACh were then examined. Dipalmitoylphosphatidylcholine decreased the levels of (/sup 3/H)-ACh. This decrease does not result from a dilution of the radioactive (/sup 3/H)-choline by nonradioactive choline derived from PC. Specifically, it is the S/sub 3/ (cytoplasmic) level of (/sup 3/H)-ACh that is decreased by DPPC treatment. This decrease appears to be partially due to lipid activation of an intraterminal cholinesterase which results in hydrolysis of nonvesicular (/sup 3/H)-ACh. The ability of the lipid to interfere with exocytosis may account for the blockade of the K/sup +/ induced (/sup 3/H)-ACh release from the P/sub 3/ (vesicular) fraction. The high affinity choline transporter was competitively inhibited by DPPC treatment when synaptosomes were treated with DPPC prior to (/sup 3/H)-choline loading; the ubiquitous low affinity transport was not affected. These effects were specific for cholinergic neurons since the uptake and release of dopamine and norepinephrine from the substantia nigra and the cortex, respectively, were not affected.

Bottiglieri, D.F.

1986-01-01

316

Lipid Thermotropic Transitions in Human Stratum Corneum  

Microsoft Academic Search

The techniques of differential scanning calorimetry (DSC) and thermal perturbation infrared (IR) spectrometry were used to investigate thermal transitions in intact, fractionated, and lipid-extracted human stratum corneum. The DSC results show 3 major and one minor thermal transition in the range of 30-120°C. Of particular interest to this study are 2 transitions seen near 65° and 75°C in intact stratum

Guia M. Golden; Donald B. Guzek; Richard R. Harris; James E. McKie; Russell O. Potts

1986-01-01

317

Ionic Permeability of Thin Lipid Membranes  

PubMed Central

Ultrathin (black) lipid membranes were made from sheep red cell lipids dissolved in n-decane. The presence of aliphatic alcohols in the aqueous solutions bathing these membranes produced reversible changes in the ionic permeability, but not the osomotic permeability. Heptanol (8 mM), for example, caused the membrane resistance (Rm) to decrease from >108 to about 105 ohm-cm2 and caused a marked increase in the permeability to cations, especially potassium. In terms of ionic transference numbers, deduced from measurements of the membrane potential at zero current, Tcat/TCl increased from about 6 to 21 and TK/TNa increased from about 3 to 21. The addition of long-chain (C8ndash;C10) alcohols to the lipid solutions from which membranes were made produced similar effects on the ionic permeability. A plot of log Rm vs. log alcohol concentration was linear over the range of maximum change in Rm, and the slope was -3 to -5 for C2 through C7 alcohols, suggesting that a complex of several alcohol molecules is responsible for the increase in ionic permeability. Membrane permselectivity changed from cationic to anionic when thorium or ferric iron (10-4 M) was present in the aqueous phase or when a secondary amine (Amberlite LA-2) was added to the lipid solutions from which membranes were made. When membranes containing the secondary amine were exposed to heptanol, Rm became very low (103–104 ohm-cm2) and the membranes became perfectly anion-selective, developing chloride diffusion potentials up to 150 mv. PMID:5535355

Gutknecht, John; Tosteson, D. C.

1970-01-01

318

Lipid transfer proteins (LTP) and atherosclerosis  

Microsoft Academic Search

This review deals with four lipid transfer proteins (LTP): three are involved in cholesteryl ester (CE) synthesis or transport, the fourth deals with plasma phospholipid (PL) transfer. Experimental models of atherosclerosis, clinical and epidemiological studies provided information as to the relationship of these LTP(s) to atherosclerosis, which is the main focus of this review. Thus, inhibition of acyl-CoA:cholesterol acyltransferase (ACAT)

O. Stein; Y. Stein

2005-01-01

319

Effective use of combination lipid therapy  

Microsoft Academic Search

Despite the benefits of statin therapy, low-density lipoprotein (LDL) cholesterol management remains suboptimal and many patients\\u000a do not achieve their recommended target goals. The aim of combination lipid drug therapy in high-risk patients is to achieve\\u000a LDL cholesterol and non-high-density lipoprotein (HDL) cholesterol goals with a minimum of serious adverse effects. Although\\u000a statins are the drug of first choice, statin

Abu R. Vasudevan; Peter H. Jones

2006-01-01

320

Medium chain triglycerides and structured lipids  

Microsoft Academic Search

Lipids are an essential component of our body composition and necessary in our daily food intake. Conventional fats and oils\\u000a are composed of glycerides of long chain fatty acids and are designated as long chain triglycerides (LCT). Body fat as well\\u000a as the fats and oils in our daily intake fall into this category. In enteral and parenteral hyperalimentation, we

Vigen K. Babayan

1987-01-01

321

Analysis of lipid droplets in hepatocytes.  

PubMed

The liver plays an important role in triacylglycerol (TG) metabolism. It can store large amounts of TG in cytosolic lipid droplets (CLDs), or it can package TG into very-low density lipoproteins (VLDL) that are secreted from the cell. TG packaged into VLDL is derived from TG stored within the endoplasmic reticulum in lumenal lipid droplets (LLDs). Therefore, the liver contains at least three kinds of LDs that differ in their protein composition, subcellular localization, and function. Hepatic LDs undergo tremendous changes in their size and protein composition depending on the energetic (fasting/feeding) and pathological (viral infection, nonalcoholic fatty liver disease, etc.) states. It is crucial to develop methodologies that allow the isolation and analyses of the various hepatic LDs in order to gain insight into the differential metabolism of these important lipid storage/transport particles in health and disease. Here, we present detailed protocols for the isolation and analysis of CLDs and LLDs and for monitoring CLD dynamics. PMID:24099290

Wang, Huajin; Quiroga, Ariel D; Lehner, Richard

2013-01-01

322

Lipid imaging by mass spectrometry - a review.  

PubMed

Mass spectrometry imaging (MSI) has proven to be extremely useful for applications such as the spatial analysis of peptides and proteins in biological tissue, the performance assessment of drugs in vivo or the measurement of protein or metabolite expression as tissue classifiers or biomarkers from disease versus control tissue comparisons. The most popular MSI technique is MALDI mass spectrometry. First invented by Richard Caprioli in the mid-1990s, it is the highest performing MSI technique in terms of spatial resolution, sensitivity for intact biomolecules and application range today. The unique ability to identify and spatially resolve numerous compounds simultaneously, based on m/z values has inter alia been applied to untargeted and targeted chemical mapping of biological compartments, revealing changes of physiological states, disease pathologies and metabolic faith and distribution of xenobiotics. Many MSI applications focus on lipid species because of the lipids' diverse roles as structural components of cell membranes, their function in the surfactant cycle, and their involvement as second messengers in signalling cascades of tissues and cells. This article gives a comprehensive overview of lipid imaging techniques and applications using established MALDI and SIMS methods but also other promising MSI techniques such as DESI. PMID:23314100

Gode, David; Volmer, Dietrich A

2013-03-01

323

Biliary lipids, water and cholesterol gallstones.  

PubMed

Cholesterol supersaturation, hydrophobic bile salts, pronucleating proteins and impaired gall-bladder motility may contribute to gallstone pathogenesis. We here show that both gallstone-susceptible C57L and gallstone-resistant AKR male inbred mice exhibit supersaturated gall-bladder biles during early lithogenesis, whereas bile-salt composition becomes hydrophobic only in susceptible C57L mice. In vitro, cholesterol crystallization occurs depending on relative amounts of lipids; excess cholesterol may exceed solubilizing capacity of mixed bile salt-phospholipid micelles, whereas excess bile salts compared with phospholipids leads to deficient cholesterol-storage capacity in vesicles. In vivo, bile lipid contents are mainly determined at the level of the hepatocyte canalicular membrane, where specific transport proteins enable lipid secretion [ABCG5/G8 (ATP-binding cassette transporter G5/G8) for cholesterol, MDR3 (multi-drug resistant 3) for phospholipid, BSEP (bile salt export pump)]. These transport proteins are regulated by farnesoid X and liver X nuclear receptors. After nascent bile formation, modulation of bile water contents in biliary tract and gall-bladder exerts critical effects on cholesterol crystallization. During progressive bile concentration (particularly in the fasting gall-bladder), cholesterol and, preferentially, phospholipid transfer occurs from cholesterol-unsaturated vesicles to emerging mixed micelles. The remaining unstable cholesterol-enriched vesicles may nucleate crystals. Various aquaporins have recently been discovered throughout the biliary tract, with potential relevance for gallstone formation. PMID:16232124

van Erpecum, Karel J

2005-11-01

324

Lipid Emulsion for Local Anesthetic Systemic Toxicity  

PubMed Central

The accidental overdose of local anesthetics may prove fatal. The commonly used amide local anesthetics have varying adverse effects on the myocardium, and beyond a certain dose all are capable of causing death. Local anesthetics are the most frequently used drugs amongst anesthetists and although uncommon, local anaesthetic systemic toxicity accounts for a high proportion of mortality, with local anaesthetic-induced cardiac arrest particularly resistant to standard resuscitation methods. Over the last decade, there has been convincing evidence of intravenous lipid emulsions as a rescue in local anesthetic-cardiotoxicity, and anesthetic organisations, over the globe have developed guidelines on the use of this drug. Despite this, awareness amongst practitioners appears to be lacking. All who use local anesthetics in their practice should have an appreciation of patients at high risk of toxicity, early symptoms and signs of toxicity, preventative measures when using local anesthetics, and the initial management of systemic toxicity with intravenous lipid emulsion. In this paper we intend to discuss the pharmacology and pathophysiology of local anesthetics and toxicity, and the rationale for lipid emulsion therapy. PMID:21969824

Ciechanowicz, Sarah; Patil, Vinod

2012-01-01

325

Plasma flux-dependent lipid A deactivation  

NASA Astrophysics Data System (ADS)

This paper reports the influence of gas plasma flux on endotoxin lipid A film deactivation. To study the effect of the flux magnitude of reactive species, a modified low-pressure inductively coupled plasma (ICP) with O radical flux ˜1016 cm-2 s-1 was used. After ICP exposures, it was observed that while the Fourier transform infrared absorbance of fatty chains responsible for the toxicity drops by 80% through the film, no obvious film endotoxin deactivation is seen. This is in contrast to that previously observed under low flux exposure conducted in a vacuum beam system: near-surface only loss of fatty chains led to significant film deactivation. Secondary ion mass spectrometry characterization of changes at the film surface did not appear to correlate with the degree of deactivation. Lipid A films need to be nearly completely removed in order to detect significant deactivation under high flux conditions. Additional high reactive species flux experiments were conducted using an atmospheric pressure helium plasma jet and a UV/ozone device. Exposure of lipid A films to reactive species with these devices showed similar deactivation behaviour. The causes for the difference between low and high flux exposures may be due to the nature of near-surface structural modifications as a function of the rate of film removal.

Chang, Hung-Wen; Hsu, Cheng-Che; Ahmed, Musahid; Liu, Suet Yi; Fang, Yigang; Seog, Joonil; Oehrlein, Gottlieb S.; Graves, David B.

2014-06-01

326

Phytic Acid Inhibits Lipid Peroxidation In Vitro  

PubMed Central

Phytic acid (PA) has been recognized as a potent antioxidant and inhibitor of iron-catalyzed hydroxyl radical formation under in vitro and in vivo conditions. Therefore, the aim of the present study was to investigate, with the use of HPLC/MS/MS, whether PA is capable of inhibiting linoleic acid autoxidation and Fe(II)/ascorbate-induced peroxidation, as well as Fe(II)/ascorbate-induced lipid peroxidation in human colonic epithelial cells. PA at 100??M and 500??M effectively inhibited the decay of linoleic acid, both in the absence and presence of Fe(II)/ascorbate. The observed inhibitory effect of PA on Fe(II)/ascorbate-induced lipid peroxidation was lower (10–20%) compared to that of autoxidation. PA did not change linoleic acid hydroperoxides concentration levels after 24 hours of Fe(II)/ascorbate-induced peroxidation. In the absence of Fe(II)/ascorbate, PA at 100??M and 500??M significantly suppressed decomposition of linoleic acid hydroperoxides. Moreover, PA at the tested nontoxic concentrations (100??M and 500??M) significantly decreased 4-hydroxyalkenal levels in Caco-2 cells which structurally and functionally resemble the small intestinal epithelium. It is concluded that PA inhibits linoleic acid oxidation and reduces the formation of 4-hydroxyalkenals. Acting as an antioxidant it may help to prevent intestinal diseases induced by oxygen radicals and lipid peroxidation products. PMID:24260736

Weglarz, Ludmila; Dzierzewicz, Zofia

2013-01-01

327

Stiffened lipid platforms at molecular force foci.  

PubMed

How mechanical forces are sensed remains largely mysterious. The forces that gate prokaryotic and several eukaryotic channels were found to come from the lipid membrane. Our survey of animal cells found that membrane force foci all have cholesterol-gathering proteins and are reinforced with cholesterol. This result is evident in overt force sensors at the tips of stereocilia for vertebrate hearing and the touch receptor of Caenorhabditis elegans and mammalian neurons. For less specialized cells, cadherins sustain the force between neighboring cells and integrins between cells and matrix. These tension bearers also pass through and bind to a cholesterol-enriched platform before anchoring to cytoskeleton through other proteins. Cholesterol, in alliance with sphingomyelin and specialized proteins, enforces a more ordered structure in the bilayer. Such a stiffened platform can suppress mechanical noise, redirect, rescale, and confine force. We speculate that such platforms may be dynamic. The applied force may allow disordered-phase lipids to enter the platform-staging channel opening in the thinner mobile neighborhood. The platform may also contain specialized protein/lipid subdomains enclosing mechanosensitive channels to open with localized tension. Such a dynamic stage can mechanically operate structurally disparate channels or enzymes without having to tie them directly to cadherin, integrin, or other protein tethers. PMID:23476066

Anishkin, Andriy; Kung, Ching

2013-03-26

328

Microorganism lipid droplets and biofuel development  

PubMed Central

Lipid droplet (LD) is a cellular organelle that stores neutral lipids as a source of energy and carbon. However, recent research has emerged that the organelle is involved in lipid synthesis, transportation, and metabolism, as well as mediating cellular protein storage and degradation. With the exception of multi-cellular organisms, some unicellular microorganisms have been observed to contain LDs. The organelle has been isolated and characterized from numerous organisms. Triacylglycerol (TAG) accumulation in LDs can be in excess of 50% of the dry weight in some microorganisms, and a maximum of 87% in some instances. These microorganisms include eukaryotes such as yeast and green algae as well as prokaryotes such as bacteria. Some organisms obtain carbon from CO2 via photosynthesis, while the majority utilizes carbon from various types of biomass. Therefore, high TAG content generated by utilizing waste or cheap biomass, coupled with an efficient conversion rate, present these organisms as bio-tech ‘factories’ to produce biodiesel. This review summarizes LD research in these organisms and provides useful information for further LD biological research and microorganism biodiesel development. [BMB Reports 2013; 46(12): 575-581] PMID:24355300

Liu, Yingmei; Zhang, Congyan; Shen, Xipeng; Zhang, Xuelin; Cichello, Simon; Guan, Hongbin; Liu, Pingsheng

2013-01-01

329

Chemical Enhancer Solubility in Human Stratum Corneum Lipids and Enhancer Mechanism of Action on Stratum Corneum Lipid Domain  

PubMed Central

Previously, chemical enhancer-induced permeation enhancement on human stratum corneum (SC) lipoidal pathway at enhancer thermodynamic activities approaching unity in the absence of cosolvents (defined as Emax) was determined and hypothesized to be related to the enhancer solubilities in the SC lipid domain. The objectives of the present study were to (a) quantify enhancer uptake into SC lipid domain at saturation, (b) elucidate enhancer mechanism(s) of action, and (c) study the SC lipid phase behavior at Emax. It was concluded that direct quantification of enhancer uptake into SC lipid domain using intact SC was complicated. Therefore a liposomal model of extracted human SC lipids was used. In the liposome study, enhancer uptake into extracted human SC lipid liposomes (EHSCLL) was shown to correlate with Emax. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and differential scanning calorimetry (DSC) were used to evaluate lipid phase alterations in enhancer-treated intact SC. IR spectra demonstrated an increase in the lipid domain fluidity and DSC thermograms indicated a decrease in the phase transition temperature with increasing Emax. These results suggest that the enhancer mechanism of action is through enhancer intercalation into SC intercellular lipids and subsequent lipid lamellae fluidization related to enhancer lipid concentration. PMID:19747970

Ibrahim, Sarah A.; Li, S. Kevin

2010-01-01

330

Zebrafish yolk lipid processing: a tractable tool for the study of vertebrate lipid transport and metabolism.  

PubMed

Dyslipidemias are a major cause of morbidity and mortality in the world, particularly in developed nations. Investigating lipid and lipoprotein metabolism in experimentally tractable animal models is a crucial step towards understanding and treating human dyslipidemias. The zebrafish, a well-established embryological model, is emerging as a notable system for studies of lipid metabolism. Here, we describe the value of the lecithotrophic, or yolk-metabolizing, stages of the zebrafish as a model for studying lipid metabolism and lipoprotein transport. We demonstrate methods to assay yolk lipid metabolism in embryonic and larval zebrafish. Injection of labeled fatty acids into the zebrafish yolk promotes efficient uptake into the circulation and rapid metabolism. Using a genetic model for abetalipoproteinemia, we show that the uptake of labeled fatty acids into the circulation is dependent on lipoprotein production. Furthermore, we examine the metabolic fate of exogenously delivered fatty acids by assaying their incorporation into complex lipids. Moreover, we demonstrate that this technique is amenable to genetic and pharmacologic studies. PMID:24812437

Miyares, Rosa L; de Rezende, Vitor B; Farber, Steven A

2014-07-01

331

Development of solid lipid nanoparticles and nanostructured lipid carriers for improving ocular delivery of acyclovir.  

PubMed

The objective of the present investigation was to improve the ocular bioavailability of acyclovir by incorporating it into solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs). This required optimization of the process parameters, such as type of lipid, drug to lipid ratios, type and concentration of surfactants, and type and amount of liquid lipids used in the formulations. SLNs and NLCs were prepared by the modified hot oil in water microemuslion method. The prepared nanoparticles were evaluated for their particle size, zeta potential, entrapment efficiency, solid state characteristics, surface morphology, in vitro drug release, and permeation through excised cornea. The prepared nanoparticles were spherical and within the size range suitable for ocular drug delivery (400-777.56?nm). Incorporation of liquid oil in the structure of SLNs resulted in the formation of NLCs with high entrapment efficiency (25-91.64%) compared to SLNs (11.14%). The drug release from SLNs and NLCs was rather a surface-based phenomenon. In comparison to free drug solution, NLCs were capable of having faster permeation through the excised cornea indicating their potential enhanced corneal penetration properties. However, SLNs have reduced the permeation rate significantly. The results of the study suggest that SLNs can be successfully converted to physically superior NLCs, which have the potential to be developed further as ocular drug delivery systems for ACV. PMID:22424312

Seyfoddin, Ali; Al-Kassas, Raida

2013-04-01

332

Multiscale Modeling of Supported Lipid Bilayers  

NASA Astrophysics Data System (ADS)

Cell membranes consist of a multitude of lipid molecules that serve as a framework for the even greater variety of membrane associated proteins [1-4]. As this highly complex (nonequilibrium) system cannot easily be understood and studied in a controlled way, a wide variety of model systems have been devised to understand the dynamics, structure, and thermodynamics in biological membranes. One such model system is a supported lipid bilayer (SLB), a two-dimensional membrane suspended on a surface. SLBs have been realized to be manageable experimentally while reproducing many of the key features of real biological membranes [5,6]. One of the main advantages of supported bilayers is the physical stability due to the solid support that enables a wide range of surface characterization techniques not available to free or unsupported membranes. As SLBs maintain some of the crucial structural and dynamic properties of biological membranes, they provide an important bridge to natural systems. In order to mimic cell membranes reliably, certain structural and dynamic features have to be reliably reproduced in the artificially constructed lipid bilayers. SLBs should display lateral mobility as in living cells, because many membrane activities involve transport, recruitment, or assembly of specific components. It is also critical for membranes to exhibit the correct thermodynamic phase, namely, a fluid lipid bilayer, to respond to environmental stress such as temperature and pressure changes [7]. There are several ways to fabricate supported lipid bilayers (SLBs) on planar substrates. One can use vesicle fusion on solid substrates [5,8-10] as well as Langmuir-Blodgett deposition [11,12]. Proteoliposome adsorption and subsequent membrane formation on a mica surface was first demonstrated by Brian and McConnell [13]. Because of its simplicity and reproducibility, this is one of the most common approaches to prepare supported membranes. A diverse range of different solid substrates has been used as support material below the bilayer [14,15]. Silicon oxide is the material of choice for vesicle fusion [16]. Polymer cushions dampen the effect of hard surfaces and therefore have been actively investigated [17-20]. However, it is not fully understood which changes the introduction of a solid support introduces into such a biomimetic system. Experimentally it is almost impossible to address such changes, as extremely highresolution data would be required.

Hoopes, Matthew I.; Xing, Chenyue; Faller, Roland

333

[Lipids, lipoproteins, arterial accidents and oral contraceptives].  

PubMed

This work reviews lipoprotein metabolism and relationships to atherosclerosis, examines the nature of arterial accidents and lipid modifications that occur with oral contraceptive (OC) use, and assesses the practical consequences for OC prescription. Cholesterol, triglycerides, and phospholipids are not soluble in aqueous milieus, and their transport in plasma is provided by macromolecules comprising a protein part and a lipid part. 5 types of these lipoproteins are distinguished by their relative richness in lipids and protein and by the nature of their proteins. The chylomicrons carry exogenous triglycerides to the peripheral tissues and cholesterol of dietary origin to the liver. Very low density lipoprotein (VLDL) cholesterol is secreted by the liver and transports triglycerides and cholesterol of endogenous origin. Low denisty lipoprotein (LDL) cholesterol originates in the degradation of VLDL cholesterol and transports cholesterol to the cells. High density lipoprotein (HDL) cholesterol is secreted by the liver and intestines or formed in the course of degradation of chylomicrons and VLDL cholesterol. Its role is to carry excess cholesterol in the peripheral tissues to the liver for elimination in the bile. Cholesterol thus follows 2 different pathways in the body: a path from the liver to the peripheral cells, whose markers are LDL and VLDL cholesterol and the plasma apoprotein B, and a path of return of excess cholesterol from the tissues and especially the arteries to the liver, marked by HDL cholesterol and the plasma apoprotein A. Only a proper balance between the 2 flows can prevent an excess of cholesterol in the arteries and the consequent constitution of atherosclerotic lesions. LDL and to a lesser extent VLDL cholesterol are strongly and positively correlated to atherogenic risk, while HDL cholesterol is negatively correlated to risk, independently of other risk factors. Arterial accidents occurring with OC use do not seem to be atheromatous in nature. A study by the Lipid Research Clinics of 2000 OC users and nonusers found that users had higher levels of total cholesterol, of triglycerides, and of LDL and VLDL cholesterol, while the elevation of HDL cholesterol was minimal. The effects of combinations of hormones in OCs depend on their composition. OCs with high or medium doses of estrogen cause an elevation in total cholesterol, triglycerides, and LDL and VLDL cholesterol. HDL cholesterol rises slightly with 19 norsteroids and declines with norgestrel. The ratio of total to HDL cholesterol is on the whole increased. OCs with low estrogen doses induce a decline inHDL cholesterol while the levels of total cholesterol and triglycerides remain unchanged. High dose progestin-only pills induce increases in LDL and decreases in HDL cholestrol. Total cholesterol tends to increases with 19 norsteroids and decline with noregestrel while triglycerides vary slightly. With smaller doses of progestin, less intense effects may be seen. The theoretic atherogenic risk determined by the levels and ratio of total and HDL cholesterol is thus increased with some hormonal combinations. OCs can be prescribed for women with normal lipid balance after a pretreatment lipid profile determination. Lipid balance should be reassessed regularly. OCs are contraindicated in cases of moderate or severe hypercholesterolemia and primary hypo HDLemia. Combined OCs may be used in cases of mild hyperlipoproteinemia in which other contraceptive methods are not possible if regular monitoring is provided. PMID:12341243

Bakir, R; Hilliquin, P

1986-01-01

334

Solid Lipid Nanoparticles of a Water Soluble Drug, Ciprofloxacin Hydrochloride  

PubMed Central

The aim of this study was to understand and investigate the relationship between experimental factors and their responses in the preparation of ciprofloxacin hydrochloride based solid lipid nanoparticles. A quadratic relationship was studied by developing central composite rotatable design. Amount of lipid and drug, stirring speed and stirring time were selected as experimental factors while particle size, zeta potential and drug entrapment were used as responses. Prior to the experimental design, a qualitative prescreening study was performed to check the effect of various solid lipids and their combinations. Results showed that changing the amount of lipid, stirring speed and stirring time had a noticeable influence on the entrapment efficiencies and particle size of the prepared solid lipid nanoparticles. The particle size of a solid lipid nanoparticle was in the range of 159-246 nm and drug encapsulation efficiencies were marginally improved by choosing a binary mixture of physically incompatible solid lipids. Release of ciprofloxacin hydrochloride from solid lipid nanoparticle was considerably slow, and it shows Higuchi matrix model as the best fitted model. Study of solid lipid nanoparticle suggested that the lipid based carrier system could potentially be exploited as a delivery system with improved drug entrapment efficiency and controlled drug release for water soluble actives. PMID:23716872

Shah, M.; Agrawal, Y. K.; Garala, K.; Ramkishan, A.

2012-01-01

335

Lipid digestion, absorption and uptake in Solea senegalensis.  

PubMed

Dietary lipids are the major energy source for metabolic purposes in most fish species, and improve dietary protein utilization for growth. In a previous study we have reported a low tolerance of Senegalese sole juveniles to dietary lipid levels and suggested a maximal dietary inclusion level of 8% lipids for both optimal growth and nutrient utilization. The mechanisms behind this apparent poor utilization of the dietary lipids are still to be elucidated. The primary aim of the present study was to investigate the overall process of digestion and lipid absorption in relation to dietary lipid levels. Triplicate groups of twenty fish (mean initial mass 29g) were fed two isonitrogenous diets (54% of protein dry matter basis) with different lipid levels (L4 and L17, 4 and 17% lipids dry matter basis), for 88days. Protein and lipid apparent digestibility coefficients as well as lipase activity were similar in both groups suggesting that Solea senegalensis has the ability to digest equally well a low fat or a high fat diet. Plasma triglyceride concentrations were significantly higher 5 and 16h after feeding in fish fed the L17 compared to those fed L4, following dietary lipid supply, demonstrating effective lipid absorption. Expression of proteins related to lipid transport (microsomal triglyceride transfer protein), trafficking (Fatty acid binding protein 11) and fatty acid uptake (VLDL-r) was significantly higher in liver of fish fed the high fat diet 16h after the meal, but remained unchanged in muscle. In conclusion, it seems that high fat diets do not impair lipid digestion and absorption. PMID:23684583

Borges, Pedro; Medale, Françoise; Veron, Vincent; Pires, Maria Dos Anjos; Dias, Jorge; Valente, Luísa M P

2013-09-01

336

Oxidized lipids enhance RANKL production by T lymphocytes: implications for lipid-induced bone loss  

PubMed Central

Osteoporosis is a systemic disease that is associated with increased morbidity, mortality and health care costs. Whereas osteoclasts and osteoblasts are the main regulators of bone homeostasis, recent studies underscore a key role for the immune system, particularly via activation-induced T lymphocyte production of Receptor Activator of NF?B Ligand (RANKL). Well-documented as a mediator of T lymphocyte/dendritic cell interactions, RANKL also stimulates the maturation and activation of bone-resorbing osteoclasts. Given that lipid oxidation products mediate inflammatory and metabolic disorders such as osteoporosis and atherosclerosis, and since oxidized lipids affect several T lymphocyte functions, we hypothesized that RANKL production might also be subject to modulation by oxidized lipids. Here, we show that short term exposure of both unstimulated and activated human T lymphocytes to minimally oxidized low density lipoprotein (LDL), but not native LDL, significantly enhances RANKL production and promotes expression of the lectin-like oxidized LDL receptor-1 (LOX-1). The effect, which is also observed with 8-iso-Prostaglandin E2, an inflammatory isoprostane produced by lipid peroxidation, is mediated via the NF?B pathway, and involves increased RANKL mRNA expression. The link between oxidized lipids and T lymphocytes is further reinforced by analysis of hyperlipidemic mice, in which bone loss is associated with increased RANKL mRNA in T lymphocytes and elevated RANKL serum levels. Our results suggest a novel pathway by which T lymphocytes contribute to bone changes, namely, via oxidized lipid enhancement of RANKL production. These findings may help elucidate clinical associations between cardiovascular disease and decreased bone mass, and may also lead to new immune-based approaches to osteoporosis. PMID:19699688

Graham, Lucia S; Parhami, Farhad; Tintut, Yin; Kitchen, Christina M. R.; Demer, Linda L.; Effros, Rita B.

2009-01-01

337

Effects of Ferulago angulata Extract on Serum Lipids and Lipid Peroxidation  

PubMed Central

Background. Nowadays, herbs they are considered to be the main source of effective drugs for lowering serum lipids and lipid peroxidation. The present experimental animal study aimed to assess the impact of Ferulago angulata on serum lipid profiles, and on levels of lipid peroxidation. Methods. Fifty male Wistar rats, weighing 250–300?g, were randomly divided into five equal groups (ten rats in each). The rat groups received different diets as follows: Group I: fat-rich diet; Group II: fat-rich diet plus hydroalcoholic extracts of Ferulago angulata at a dose of 400?mg/kg; Group III: fat-rich diet plus hydroalcoholic extracts of Ferulago angulata at a dose of 600?mg/kg; Group IV: fat-rich diet plus atorvastatin; Group V: common stock diet. The levels of serum glucose and lipids and the atherogenic index were measured. In addition, malondialdehyde (MDA), thiol oxidation, carbonyl concentrations, C-reactive proteins, and antioxidant capacity were evaluated in each group of rats. Results. Interestingly, by adding a hydroalcoholic extract of Ferulago angulata to the high-fat diet, the levels of total cholesterol and low-density lipoproteins (LDL) in the high-fat diet rats were both significantly reduced. This result was considerably greater compared to when atorvastatin was added as an antilipid drug. The beneficial effects of the Ferulago angulata extract on lowering the level of triglycerides was observed only when a high dosage of this plant extraction was added to a high fat diet. Furthermore, the level of malondialdehyde, was significantly affected by the use of the plant extract in a high-fat diet, compared with a normal regimen or high-fat diet alone. Conclusion. Administration of a hydroalcoholic extract of Ferulago angulata can reduce serum levels of total cholesterol, triglycerides, and LDL. It can also inhibit lipid peroxidation. PMID:24707310

Rafieian-kopaei, Mahmoud; Shahinfard, Najmeh; Rouhi-Boroujeni, Hojjat; Gharipour, Mojgan; Darvishzadeh-Boroujeni, Pariya

2014-01-01

338

Effects of Ferulago angulata Extract on Serum Lipids and Lipid Peroxidation.  

PubMed

Background. Nowadays, herbs they are considered to be the main source of effective drugs for lowering serum lipids and lipid peroxidation. The present experimental animal study aimed to assess the impact of Ferulago angulata on serum lipid profiles, and on levels of lipid peroxidation. Methods. Fifty male Wistar rats, weighing 250-300?g, were randomly divided into five equal groups (ten rats in each). The rat groups received different diets as follows: Group I: fat-rich diet; Group II: fat-rich diet plus hydroalcoholic extracts of Ferulago angulata at a dose of 400?mg/kg; Group III: fat-rich diet plus hydroalcoholic extracts of Ferulago angulata at a dose of 600?mg/kg; Group IV: fat-rich diet plus atorvastatin; Group V: common stock diet. The levels of serum glucose and lipids and the atherogenic index were measured. In addition, malondialdehyde (MDA), thiol oxidation, carbonyl concentrations, C-reactive proteins, and antioxidant capacity were evaluated in each group of rats. Results. Interestingly, by adding a hydroalcoholic extract of Ferulago angulata to the high-fat diet, the levels of total cholesterol and low-density lipoproteins (LDL) in the high-fat diet rats were both significantly reduced. This result was considerably greater compared to when atorvastatin was added as an antilipid drug. The beneficial effects of the Ferulago angulata extract on lowering the level of triglycerides was observed only when a high dosage of this plant extraction was added to a high fat diet. Furthermore, the level of malondialdehyde, was significantly affected by the use of the plant extract in a high-fat diet, compared with a normal regimen or high-fat diet alone. Conclusion. Administration of a hydroalcoholic extract of Ferulago angulata can reduce serum levels of total cholesterol, triglycerides, and LDL. It can also inhibit lipid peroxidation. PMID:24707310

Rafieian-Kopaei, Mahmoud; Shahinfard, Najmeh; Rouhi-Boroujeni, Hojjat; Gharipour, Mojgan; Darvishzadeh-Boroujeni, Pariya

2014-01-01

339

Response of pigeon guillemots to variable abundance of high-lipid and low-lipid prey  

USGS Publications Warehouse

Populations of the pigeon guillemot (Cepphus columba) and other piscivores have been in decline for several decades in the Gulf of Alaska and Bering Sea, and a decline in abundance of lipid-rich schooling fishes is hypothesized as the major cause. We tested this hypothesis by studying the breeding biology of pigeon guillemots during 1995-1999 while simultaneously measuring prey abundance with beach seines and bottom trawls. Our study area (Kachemak Bay, Alaska) comprises two oceanographically distinct areas. Populations of a lipid-rich schooling fish, Pacific sand lance (Ammodytes hexapterus), were higher in the warmer Inner Bay than in the colder Outer Bay, and sand lance abundance was higher during warm years. Populations of low-lipid content demersal fishes were similar between areas. Chick survival to age 15 days was 47% higher in the Inner Bay (high-lipid diet) than in the Outer Bay (low-lipid diet), and estimated reproductive success (chicks fledged nest-1) was 62% higher in the Inner Bay than in the Outer Bay. Chick provisioning rate (kJ chick-1 h-1) increased with the proportion of sand lance in the diet (r2=0.21), as did growth rate (g day-1) of younger (beta) chicks in two-chick broods (r2=0.14). Pigeon guillemots in the Inner Bay switched to demersal prey during years of below-average sand lance abundance, and these birds reacted to 38-fold interannual changes in sand lance abundance with reductions in beta chick growth rates, with no decline in beta chick survival. In contrast, the proportion of nests experiencing brood reduction in the Outer Bay (demersal diet) increased >300% during years of below-average demersal abundance, although demersal fish abundance varied only 4-fold among years. Our results support the hypothesis that recovery of pigeon guillemot populations from the effects of the Exxon Valdez oil spill is limited by availability of lipid-rich prey.

Litzow, M. A.; Piatt, J. F.; Prichard, A. K.; Roby, D. D.

2002-01-01

340

Molecular modeling of proteinlike inclusions in lipid bilayers: Lipid-mediated interactions  

NASA Astrophysics Data System (ADS)

We investigated the insertion of transmembrane structures in a lipid bilayer and their interactions using self-consistent field theory. The lipids are coarse-grained on a united-atom level and consist of a phosphatidylcholinelike headgroup and two hydrophobic tails. The inclusions, acting as simple models for proteins that span biological membranes, are rigid rods (radius R ) with a hydrophobic surface and hydrophilic end caps. The insertion free energy ? of an individual rod is strongly regulated by the affinity between its hydrophobic surface and the lipid tails. This affinity also controls the best match of the hydrophobic length of the rod with that of the bilayer. The line tension ?(=?/2?R) is practically independent of R . The perturbations in the bilayer as a function of distance from the inclusion, have the shape of a damped oscillation. The wavelength and decay length are related to the elastic properties of the bilayer and do not depend on R . These results are used to analyze how the lipid matrix affects the interaction between transmembrane objects, for computational reasons considering the limit of R?? . Contributions on different length scales can be distinguished: (i) a long-range elastic interaction, which is an exponentially decaying oscillation; (ii) an exponentially decaying repulsion on an intermediate length scale, resulting from the loss of conformational entropy of the lipid tails; and (iii) a short-range interaction due to the finite compressibility of the lipid tails, which manifests either as a depletion attraction if there is no affinity between the tails and the inclusions’ surface or, otherwise, as an oscillatory structural force.

Kik, Richard A.; Leermakers, Frans A. M.; Kleijn, J. Mieke

2010-02-01

341

2013 PLANT LIPIDS GORDON RESEARCH CONFERENCE AND GORDON RESEARCH SEMINAR (JANUARY 27-FEBRUARY 1, 2013 - HOTEL GALVEZ, GALVESTON TX)  

SciTech Connect

Presenters will discuss the latest advances in plant and algal lipid metabolism, oil synthesis, lipid signaling, lipid visualization, lipid biotechnology and its applications, the physiological and developmental roles of lipids, and plant lipids in health. Sessions include: Producing Nutritional Lipids; Metabolic biochemistry in the next decade; Triacylglycerols: Metabolism, function, and as a target for engineering; Lipids in Protection, Reproduction, and Development; Genetic and Lipidomic Approaches to Understanding Lipid Metabolism and Signaling; Lipid Signaling in Stress Responses; New Insights on the Path to Triacylglycerols; Membrane Lipid Signaling; Lipid Visualization; Development of Biofuels and Industrial Lipids.

Welti, Ruth

2012-11-01

342

Effects of natural antioxidants on iron-catalyzed lipid oxidation of structured lipid-based emulsions  

Microsoft Academic Search

The effects of iron, pH, and natural antioxidants (?-tocopherol, gallic acid, and quercetin) on oxidation of structured lipid-based\\u000a emulsions were evaluated. Ten percent oil-in-water emulsions were formulated with a canola oil\\/caprylic acid structured lipid\\u000a and stabilized with 0.5% whey protein isolate. The PV, anisidine values, and Totox values of emulsions stored at 50C were\\u000a measured over a 15-d period. Iron

Hannah T. Osborn; Casimir C. Akoh

2003-01-01

343

Lipid and lipid mediator profiling of human synovial fluid in rheumatoid arthritis patients by means of LC-MS/MS  

PubMed Central

Human synovial fluid (SF) provides nutrition and lubrication to the articular cartilage. Particularly in arthritic diseases, SF is extensively accumulating in the synovial junction. During the last decade lipids have attracted considerable attention as their role in the development and resolution of diseases became increasingly recognized. Here, we describe a capillary LC-MS/MS screening platform that was used for the untargeted screening of lipids present in human SF of rheumatoid arthritis (RA) patients. Using this platform we give a detailed overview of the lipids and lipid – derived mediators present in the SF of RA patients. Almost 70 different lipid components from distinct lipid classes were identified and quantification was achieved for the lysophosphatidylcholine and phosphatidylcholine species. In addition, we describe a targeted LC-MS/MS lipid mediator metabolomics strategy for the detection, identification and quantification of maresin 1, lipoxin A4 and resolvin D5 in SF from RA patients. Additionally, we present the identification of 5S,12S-diHETE as a major marker of lipoxygenase pathway interactions in the investigated SF samples. These results are the first to provide a comprehensive approach to the identification and profiling of lipids and lipid mediators present in SF and to describe the presence of key anti-inflammatory and pro-resolving lipid mediators identified in SF from RA patients. PMID:22841830

Giera, Martin; Ioan-Facsinay, Andreea; Toes, Rene; Gao, Fei; Dalli, Jesmond; Deelder, Andre M; Serhan, Charles N; Mayboroda, Oleg A

2012-01-01

344

Lipid accumulation in prosthetic vascular grafts. Experimental study.  

PubMed Central

The present study demonstrates that the endoprosthetic tissue, developed at the contact of Dacron and Gore-Tex vascular prostheses replacing the infrarenal aortae of healthy dogs, presents a particular lipidic pattern as compared with the adjacent intimal arterial layer. The modified lipidic pattern is characterized by a significant increase in the total amounts of cholesterol, phospholipids, and triglycerides, despite a normal lipidic plasma profile. Histochemical studies showed that lipid droplets are accumulated in the cytoplasm of deeply situated cells and in the extracellular matrix. These findings support the idea that lipids may be trapped within the pseudo-intima of synthetic vascular grafts, even in the absence of a major plasma lipid disorder, and contribute to the prosthesis failure. Images Figure 2 Figure 4 Figure 5 Figure 6 PMID:2399933

Chignier, E.; Guidollet, J.; Lhopital, C.; Louisot, P.; Eloy, R.

1990-01-01

345

Lipid-mediated interactions between intrinsic molecules in bilayer membranes  

NASA Astrophysics Data System (ADS)

The effect of intrinsic molecules (impurities) dissolved in phospholipid bilayers on their lipid enviroment and the related lipid-mediated interactions between such molecules are examined in terms of a ten-state model for lipid chain configurations and interchain interactions. The numerical parameters used in the calculations were previously obtained by fitting to experimental data. Numerical results are presented for the case when the impurity is a cholesterol molecule, a protein, or a vacancy and when the lipid bilayer is either in the gel or fluid (liquids crystal) phase. The calculations indicate that proteins fluidize their lipid environment when the bilayer is in the gel phase. The resulting lipid-mediated interaction is shown to be short range and to have a different behavior below and above the main gel-fluid phase transition. The relation to previous theories is discussed in the final section.

Tessier-Lavigne, M.; Boothroyd, A.; Zuckermann, M. J.; Pink, D. A.

1982-05-01

346

Enhanced lipid extraction from algae using free nitrous acid pretreatment.  

PubMed

Lipid extraction has been identified as a major bottleneck for large-scale algal biodiesel production. In this work free nitrous acid (FNA) is presented as an effective and low cost pretreatment to enhance lipid recovery from algae. Two batch tests, with a range of FNA additions, were conducted to disrupt algal cells prior to lipid extraction by organic solvents. Total accessible lipid content was quantified by the Bligh and Dyer method, and was found to increase with pretreatment time (up to 48 h) and FNA concentration (up to 2.19 mg HNO2-N/L). Hexane extraction was used to study industrially accessible lipids. The mass transfer coefficient (k) for lipid extraction using hexane from algae treated with 2.19 mg HNO2-N/L FNA was found to be dramatically higher than for extraction from untreated algae. Consistent with extraction results, cell disruption analysis indicated the disruption of the cell membrane barrier. PMID:24632439

Bai, Xue; Naghdi, Forough Ghasemi; Ye, Liu; Lant, Paul; Pratt, Steven

2014-05-01

347

Phase transitions in supported lipid bilayers studied by AFM.  

PubMed

We review the capabilities of Atomic Force Microscopy (AFM) in the study of phase transitions in Supported Lipid Bilayers (SLBs). AFM represents a powerful technique to cover the resolution range not available to fluorescence imaging techniques and where spectroscopic data suggest what the relevant lateral scale for domain formation might be. Phase transitions of lipid bilayers involve the formation of domains characterized by different heights with respect to the surrounding phase and are therefore easily identified by AFM in liquid solution once the bilayer is confined to a flat surface. Even if not endowed with high time resolution, AFM allows light to be shed on some aspects related to lipid phase transitions in the case of both a single lipid component and lipid mixtures containing sterols also. We discuss here the obtained results in light of the peculiarities of supported lipid bilayer model systems. PMID:25090108

Alessandrini, Andrea; Facci, Paolo

2014-10-01

348

Maternal lipids in pre-eclampsia: innocent bystander or culprit?  

PubMed

Pre-eclampsia continues to be a challenge - to understand the underlying pathogenesis and to prevent or treat in the clinical setting. One area of potential therapies opening up is treatment of maternal lipids and clinical trials are underway using statins in early pre-eclampsia. At present, most potential therapies to treat lipids cannot be recommended for general use in pregnancy and if we were to target maternal lipids to reduce rates of pre-eclampsia, very large numbers of women may need to be treated. Prior to reaching that point, we first need to understand whether maternal lipids are pathogenic in the processes underlying pre-eclampsia. The aim of this review is to examine the role of lipids in the pathogenesis and outcomes of pre-eclampsia, how abnormal lipid genes may be implicated and consider whether treatment of hyperlipidemia has a more general place in the prevention or treatment of pre-eclampsia. PMID:25121342

Barrett, Helen L; Dekker Nitert, Marloes; McIntyre, H David; Callaway, Leonie K

2014-11-01

349

Enhanced lipid production in Chlorella pyrenoidosa by continuous culture.  

PubMed

Usually microalgae growth and lipid accumulation do not run in parallel throughout cultivation, which necessarily lowers overall lipid productivity. However, we show through batch and feed-batch studies of Chlorella pyrenoidosa XQ-20044 that by varying the nitrate concentration, conditions which produce fairly high lipid content could be achieved without sacrificing algal growth. Simultaneous microalgae growth and lipid production was achieved in continuous chemostat culture when the specific nitrate input rate was in the range of 0.78-4.56mmolg(-1)d(-1). Moreover, the maximum lipid productivity (144.93mgL(-1)d(-1)) in the continuous culture was significantly higher than in batch culture (96.28mgL(-1)d(-1)), thus indicating the feasibility and great advantage of one-step production of microalgal lipids. PMID:24717322

Wen, Xiaobin; Geng, Yahong; Li, Yeguang

2014-06-01

350

Enzyme-assisted aqueous extraction of lipid from microalgae.  

PubMed

An improved lipid extraction process has been established for microalgal using enzyme-assisted aqueous extraction processing (EAEP), which mainly involved in sonication and enzyme treatment. As compared to cellulase, neutral protease and alkaline protease, significantly higher lipid recovery was achieved by snailase and trypsin. The highest lipid recovery of 49.82% was obtained by a combined sonication-enzyme treatment at pH 4. The enhancement mechanism of the EAEP was analyzed in terms of the particle size of cream and zeta potential. In addition, microalgal lipid recovery was also affected by lipid class composition and the type of algae. The present study demonstrates a promising alternative to conventional lipid extraction of microalgae and the quantitative information on EAEP of oleaginous alga can provide valuable data for process design at pilot and industrial scale. PMID:23072503

Liang, Kehong; Zhang, Qinghua; Cong, Wei

2012-11-28

351

New applications of mass spectrometry in lipid analysis.  

PubMed

Mass spectrometry has emerged as a powerful tool for the analysis of all lipids. Lipidomic analysis of biological systems using various approaches is now possible with a quantitative measurement of hundreds of lipid molecular species. Although availability of reference and internal standards lags behind the field, approaches using stable isotope-labeled derivative tagging permit precise determination of specific phospholipids in an experimental series. The use of reactivity of ozone has enabled assessment of double bond positions in fatty acyl groups even when species remain in complex lipid mixtures. Rapid scanning tandem mass spectrometers are capable of quantitative analysis of hundreds of targeted lipids at high sensitivity in a single on-line chromatographic separation. Imaging mass spectrometry of lipids in tissues has opened new insights into the distribution of lipid molecular species with promising application to study pathophysiological events and diseases. PMID:21632539

Murphy, Robert C; Gaskell, Simon J

2011-07-22

352

Apoptosis-induced mitochondrial dysfunction causes cytoplasmic lipid droplet formation  

PubMed Central

A characteristic of apoptosis is the rapid accumulation of cytoplasmic lipid droplets, which are composed largely of neutral lipids. The proton signals from these lipids have been used for the non-invasive detection of cell death using magnetic resonance spectroscopy. We show here that despite an apoptosis-induced decrease in the levels and activities of enzymes involved in lipogenesis, which occurs downstream of p53 activation and inhibition of the mTOR signaling pathway, the increase in lipid accumulation is due to increased de novo lipid synthesis. This results from inhibition of mitochondrial fatty acid ?-oxidation, which coupled with an increase in acyl-CoA synthetase activity, diverts fatty acids away from oxidation and into lipid synthesis. The inhibition of fatty acid oxidation can be explained by a rapid rise in mitochondrial membrane potential and an attendant increase in the levels of reactive oxygen species. PMID:22460322

Boren, J; Brindle, K M

2012-01-01

353

Drug release mechanisms of cast lipid implants.  

PubMed

The aim of this work was to better understand which physicochemical processes are involved in the control of drug release from lipid implants prepared by melting and casting. Lipid implants gain steadily in importance as controlled parenteral drug delivery systems: In contrast to PLGA-based devices, no acidic microclimates are created, which can inactivate incorporated drugs. The melting and casting method offers various advantages over the commonly used direct compression technique. For example, powder de-mixing during manufacturing and highly challenging scale-up due to poor powder flowability are avoided. Importantly, broad spectra of drug release patterns can be easily provided by varying the type of lipid. The resulting drug release rates are generally lower than those of implants prepared by direct compression. This is probably due to the differences in the microstructure of the pore network of the systems. Drug or water diffusion plays a dominant role for the control of drug release, potentially combined with limited drug solubility effects, caused by the low amounts of water available within the implants. In the case of pure diffusion control, a mechanistic realistic mathematical theory is proposed, which allows for quantitative predictions of the effects of formulation parameters on the resulting drug release kinetics. Importantly, these theoretical predictions could be successfully confirmed by independent experiments. Thus, the obtained new insight into the underlying drug release mechanisms can significantly facilitate the optimization of this type of advanced drug delivery systems. This is particularly helpful if long release periods are targeted, requiring time-consuming experimental studies. PMID:21352913

Kreye, F; Siepmann, F; Willart, J F; Descamps, M; Siepmann, J

2011-08-01

354

Nile red: a selective fluorescent stain for intracellular lipid droplets  

Microsoft Academic Search

We report that the dye nile red, 9-diethylamino-5H-benzo(a)phenoxazine-5-one, is an excellent vital stain for the detection of intracellular lipid droplets by fluorescence microscopy and flow cytofluorometry. The specificity of the dye for lipid droplets was assessed on cultured aortic smooth muscle cells and on cultured peritoneal macrophages that were incubated with acetylated low density lipoprotein to induce cytoplasmic lipid overloading.

PHILLIP GREENSPAN; EUGENE P. MAYER; STANLEY D. FOWLER

1985-01-01

355

Lipid analyses of isolated surface membranes of Leishmania Donovani promastigotes  

Microsoft Academic Search

Constituent lipids of surface membranes (SM) isolated fromLeishmania donovani promastigotes were analyzed and compared with those obtained from whole cells and an isolated kinetoplast-mitochondrion fraction\\u000a (KM). On a dry weight basis, the total extractable lipids constituted ?47%, 12% and 24% of the SM, cells and KM, respectively.\\u000a The total lipids of SM, cells and KM all were composed of ?70%

Momtaz K. Wassef; Thomas B. Fioretti; Dennis M. Dwyer

1985-01-01

356

Lipid peroxidation, calcium, iron, and TCDD toxicity in rats  

SciTech Connect

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) has been studied as a prototype of halogenated aromatic hydrocarbons. Previous studies have shown that TCDD enhances hepatic lipid peroxidation. This study on TCDD administration to rats was conducted to: measure induction of lipid peroxidation in hepatic and extrahepatic tissues; compare lipid peroxidation between sexes; determine the contributions of H/sub 2/O/sub 2/ and other reactive oxygen species and associated enzymes on hepatic lipid peroxidation: determine the role of iron in TCDD-induced lipid peroxidation; and investigate the relationship between TCDD-induced alterations in lipid peroxidation, calcium homeostasis, reduced glutathione content (GSH) and selenium-dependent glutathione peroxidase activity (GSH-Px). The results demonstrated that TCDD induces changes in microsomal lipid peroxidation in hepatic and extrahepatic tissues. The rates of microsomal lipid peroxidation in male rats were less than in microsomes from female rats. TCDD treatment produced a significant increase in lipid peroxidation which preceded an increase in whole homogenate and mitochondrial calcium content, but paralleled an increase in microsomal calcium content. TCDD treatment produced dose and time dependent decreases in hepatic GSH content and GSH-Px activity in female rats. H/sub 2/O/sub 2/ and possibly hydroxyl radical and singlet oxygen are involved in TCDD-induced hepatic microsomal lipid peroxidation. The results support the hypothesis that the toxicity of TCDD and its lack of tissue selectivity in male and female rats may be due in part to lipid peroxidation. Lipid peroxidation may alter membrane permeability to calcium and lead to sequestration of calcium.

Al-Bayati, Z.A.F.

1986-01-01

357

Temperature shifts in regulation of lipids accumulated by Lipomyces starkeyi  

Microsoft Academic Search

The effect of temperature on the accumulating triglycerides ofLipomyces starkeyi was studied in 10-L fermentation experiments. The temperature during the growth, lipid accumulation and postaccumulation\\u000a phases was altered. The cellular lipid content, the glucose conversion efficiency and the specific lipid production rate were\\u000a highest when the growth phase temperature was 28C, instead of 16–18C. The temperature of the accumulation phase

M. Suutari; P. Priha; S. Laakso

1993-01-01

358

The phase behavior of cationic lipid-DNA complexes.  

PubMed Central

We present a theoretical analysis of the phase behavior of solutions containing DNA, cationic lipids, and nonionic (helper) lipids. Our model allows for five possible structures, treated as incompressible macroscopic phases: two lipid-DNA composite (lipoplex) phases, namely, the lamellar (L(alpha)(C)) and hexagonal (H(II)(C)) complexes; two binary (cationic/neutral) lipid phases, that is, the bilayer (L(alpha)) and inverse-hexagonal (H(II)) structures, and uncomplexed DNA. The free energy of the four lipid-containing phases is expressed as a sum of composition-dependent electrostatic, elastic, and mixing terms. The electrostatic free energies of all phases are calculated based on Poisson-Boltzmann theory. The phase diagram of the system is evaluated by minimizing the total free energy of the three-component mixture with respect to all the compositional degrees of freedom. We show that the phase behavior, in particular the preferred lipid-DNA complex geometry, is governed by a subtle interplay between the electrostatic, elastic, and mixing terms, which depend, in turn, on the lipid composition and lipid/DNA ratio. Detailed calculations are presented for three prototypical systems, exhibiting markedly different phase behaviors. The simplest mixture corresponds to a rigid planar membrane as the lipid source, in which case, only lamellar complexes appear in solution. When the membranes are "soft" (i.e., low bending modulus) the system exhibits the formation of both lamellar and hexagonal complexes, sometimes coexisting with each other, and with pure lipid or DNA phases. The last system corresponds to a lipid mixture involving helper lipids with strong propensity toward the inverse-hexagonal phase. Here, again, the phase diagram is rather complex, revealing a multitude of phase transitions and coexistences. Lamellar and hexagonal complexes appear, sometimes together, in different regions of the phase diagram. PMID:10733951

May, S; Harries, D; Ben-Shaul, A

2000-01-01

359

Evolution of the Kdo2-lipid A Biosynthesis in Bacteria  

Microsoft Academic Search

BACKGROUND: Lipid A is the highly immunoreactive endotoxic center of lipopolysaccharide (LPS). It anchors the LPS into the outer membrane of most Gram-negative bacteria. Lipid A can be recognized by animal cells, triggers defense-related responses, and causes Gram-negative sepsis. The biosynthesis of Kdo2-lipid A, the LPS substructure, involves with nine enzymatic steps. RESULTS: In order to elucidate the evolutionary pathway

S Opiyo; R Pardy; H Moriyama; E Moriyama

2011-01-01

360

Evolution of the Kdo2-lipid A biosynthesis in bacteria  

Microsoft Academic Search

BACKGROUND: Lipid A is the highly immunoreactive endotoxic center of lipopolysaccharide (LPS). It anchors the LPS into the outer membrane of most Gram-negative bacteria. Lipid A can be recognized by animal cells, triggers defense-related responses, and causes Gram-negative sepsis. The biosynthesis of Kdo2-lipid A, the LPS substructure, involves with nine enzymatic steps. RESULTS: In order to elucidate the evolutionary pathway

Stephen O Opiyo; Rosevelt L Pardy; Hideaki Moriyama; Etsuko N Moriyama

2010-01-01

361

Cellular lipid accumulation by Pseudomonas aeruginosa 44T1  

Microsoft Academic Search

Growth of Pseudomonas aeruginosa strain 44T1 on glucose, an n-alkane mixture or olive oil was characterized by the formation of intracellular lipid inclusions and extracellular accumulation of rhamnolipids. Maximum values of cellular lipid accumulation were obtained in olive-oil-grown cells and reached up to 38% w\\/w of its dry biomass. The principal fatty acids of cellular lipids drived from P. aeruginosa

C. de AndrOs; M. J. Espuny; M. Robert; M. E. Mercadé; A. Manresa; J. Guinea

1991-01-01

362

Lipid Metabolism of Rumen Ciliates and Bacteria  

PubMed Central

Washed suspensions of the ruminal ciliates, Isotricha prostoma and Entodinium simplex, concentrated C14-labeled oleic, palmitic, stearic, and linoleic acids within the cells during short incubation periods. Radioautographs demonstrated that oleic acid-1-C14 was hydrogenated to stearic acid by I. prostoma, and Warburg manometric data showed that the sodium salts of oleic, valeric, caproic, and acetic acids, and methyl myristate, methyl laurate, and the triglyceride tributyrin stimulated fermentation of I. prostoma. The total lipid and free fatty acid contents of I. prostoma were determined. PMID:13951437

Gutierrez, J.; Williams, P. P.; Davis, R. E.; Warwick, E. J.

1962-01-01

363

Lipid profiles of judo athletes during Ramadan.  

PubMed

The effect of Ramadan intermittent fasting (RIF) was studied on a battery of blood lipid markers in 15 elite judo athletes during a period when they were maintaining their training load without competing. Nine-to-twelve hours postprandial serum lipid and lipoproteins were measured on five occasions: before, three times during Ramadan, and three weeks post-Ramadan. Dietary data were collected using a 24-hour recall method for three days before, during and after the Ramadan month. Mean energy intake (12.9 MJ/d) remained similar throughout the study as did the macronutrient constituents of the diet. Mean body mass was slightly reduced (2 %; p < 0.01) by the end of Ramadan due mainly to a 0.65 +/- 0.68 kg decrease in body fat (p < 0.05). The RIF produced significant changes in some of the blood lipid levels: both HDL-C and LDL-C increased by 0.12 (p < 0.01) and 0.20 mmol . l (-1) (p < 0.05), respectively. During Ramadan, mean non-esterified fatty acid (NEFA) levels decreased from 0.73 to 0.28 mmol . l (-1) (p < 0.01) during the first week, then increased (p < 0.05) to 1.22 mmol . l (-1) over the middle of Ramadan and recovered to pre-Ramadan concentrations for the end and the post-Ramadan periods. Apolipoprotein A1 (Apo-A1) levels were significantly elevated at the end (p < 0.01) and the post-Ramadan periods (p < 0.05). Three weeks after Ramadan, blood levels of glucose, NEFA, Apo-A1, and Apo-B did not return to the values observed before Ramadan. In conclusion, the present results show that the combination of the change in diet pattern during Ramadan, along with intense exercise training, induced a significant decrease in body mass associated with a reduction in body fat and changes in some of the serum lipids and lipoproteins. Nevertheless, all the measured serum parameters remained within normal levels for young and active individuals. The volunteers, in this study, were able to maintain a constant training load during RIF. PMID:17879887

Chaouachi, A; Chamari, K; Roky, R; Wong, P; Mbazaa, A; Bartagi, Z; Amri, M

2008-04-01

364

Effective use of combination lipid therapy  

Microsoft Academic Search

Despite the benefits of statin therapy, low-density lipoprotein cholesterol (LDL-C) management remains suboptimal and many\\u000a patients do not achieve their recommended target goals. The aim of combination lipid drug therapy in high-risk patients is\\u000a to achieve LDL-C and non-high-density lipoprotein cholesterol (HDL-C) goals with a minimum of serious adverse effects. Although\\u000a statins are the drug of first choice, statin monotherapy

Abu R. Vasudevan; Peter H. Jones

2005-01-01

365

Diffraction studies on natural and model lipid bilayers  

NASA Astrophysics Data System (ADS)

In this study we have used neutron diffraction to examine the swelling behaviour and bilayer parameters of membranes reconstituted from polar lipids extracted from B. subtilis and model systems composed of synthetic phospholipids. Evidence for phase separation in the model system (lacking in Lysyl-PG, L-PG) is discussed in relation to its possible contribution to membrane domain formation through lipid-lipid interactions. Comparing these results with those obtained from the bilayers composed of lipids extracted from bacterial cells gives us some indication of the role of L-PG in the B. subtilis plasma membrane.

Sebastiani, F.; Harvey, R.; Khanniche, S.; Artero, J.-B.; Haertlein, M.; Fragneto, G.

2012-11-01

366

Using Monomolecular Films to Characterize Lipid Lateral Interactions  

PubMed Central

Summary Membrane lipids are structurally diverse in ways that far exceed the role envisioned by Singer and Nicholson of simply providing a fluid bilayer matrix in which proteins reside. Current models of lipid organization in membranes postulate that lipid structural diversity enables nonrandom lipid mixing in each leaflet of the bilayer, resulting in regions with special physical and functional properties, i.e., microdomains. Central to understanding the tendencies of membrane lipids to mix nonrandomly in biomembranes is the identification and evaluation of structural features that control membrane lipid lateral mixing interactions in simple model membranes. The surface balance provides a means to evaluate the lateral interactions among different lipids at a most fundamental level—mixed in binary/ternary combinations that self-assemble at the air–water interface as monomolecular films, i.e., monolayers. Analysis of surface pressure and interfacial potential as a function of average cross-sectional molecular area provide insights into hydrocarbon chain ordering, lateral compressibility/elasticity, and dipole effects under various conditions including those that approximate one leaflet of a bilayer. Although elegantly simple in principle, effective use of the surface balance requires proper attention to various experimental parameters, which are described herein. Adequate attention to these experimental parameters ensures that meaningful insights are obtained into the lipid lateral interactions and enables lipid monolayers to serve as a basic platform for use with other investigative approaches. PMID:18214373

Brown, Rhoderick E.; Brockman, Howard L.

2008-01-01

367

Depth resolved detection of lipid using spectroscopic optical coherence tomography  

PubMed Central

Optical frequency domain imaging (OFDI) can identify key components related to plaque vulnerability but can suffer from artifacts that could prevent accurate identification of lipid rich regions. In this paper, we present a model of depth resolved spectral analysis of OFDI data for improved detection of lipid. A quadratic Discriminant analysis model was developed based on phantom compositions known chemical mixtures and applied to a tissue phantom of a lipid-rich plaque. We demonstrate that a combined spectral and attenuation model can be used to predict the presence of lipid in OFDI images. PMID:24009991

Fleming, Christine P.; Eckert, Jocelyn; Halpern, Elkan F.; Gardecki, Joseph A.; Tearney, Guillermo J.

2013-01-01

368

Thermal stability of ladderane lipids as determined by hydrous pyrolysis  

USGS Publications Warehouse

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

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

2008-01-01

369

21 CFR 862.1470 - Lipid (total) test system.  

...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Chemistry Test Systems § 862.1470 Lipid (total) test system. (a)...

2014-04-01

370

Effects of sulfur dioxide on lichen lipids and fatty acids.  

PubMed

Lipids and fatty acids were studied in some lichen species after exposure to 1 ppm of aqueous sulfur dioxide. The changes in lipid composition are specific to the lichen species tested. The exposure of lichens to SO2 resulted in a slight reduction of the total phospholipid content. The amount of betaine lipid diacylglyceryltrimethylhomoserine was increased in Stereocaulon paschale, but the level of this lipid was not changed in Peltigera aphthosa. An increase in fatty acid unsaturation in lichens in response to the effect of SO2 probably has adaptive significance. PMID:9986914

Bychek-Guschina, I A; Kotlova, E R; Heipieper, H

1999-01-01

371

ARFGAP1 Is Dynamically Associated with Lipid Droplets in Hepatocytes  

PubMed Central

The ARF GTPase Activating Protein 1 (ARFGAP1) associates mainly with the cytosolic side of Golgi cisternal membranes where it participates in the formation of both COPI and clathrin-coated vesicles. In this study, we show that ARFGAP1 associates transiently with lipid droplets upon addition of oleate in cultured cells. Also, that addition of cyclic AMP shifts ARFGAP1 from lipid droplets to the Golgi apparatus and that overexpression and knockdown of ARFGAP1 affect lipid droplet formation. Examination of human liver tissue reveals that ARFGAP1 is found associated with lipid droplets at steady state in some but not all hepatocytes. PMID:25397679

Alamri, Hussam; Feng, Shi Bo; Kalantari, Fariba; Negi, Sarita; Wong, Amy H. Y.; Mazur, Alexander; Asp, Lennart; Fazel, Ali; Salman, Ayat; Lazaris, Anthoula; Metrakos, Peter; Bergeron, John J. M.; Nilsson, Tommy

2014-01-01

372

Emerging methodologies to investigate lipid-protein interactions  

PubMed Central

Cellular membranes are composed of hundreds of different lipids, ion channels, receptors and scaffolding complexes that act as signalling and trafficking platforms for processes fundamental to life. Cellular signalling and membrane trafficking are often regulated by peripheral proteins, which reversibly interact with lipid molecules in highly regulated spatial and temporal fashions. In most cases, one or more modular lipid-binding domain(s) mediate recruitment of peripheral proteins to specific cellular membranes. These domains, of which more than 10 have been identified since 1989, harbour structurally selective lipid-binding sites. Traditional in vitro and in vivo studies have elucidated how these domains coordinate their cognate lipids and thus how the parent proteins associate with membranes. Cellular activities of peripheral proteins and subsequent physiological processes depend upon lipid binding affinities and selectivity. Thus, the development of novel sensitive and quantitative tools is essential in furthering our understanding of the function and regulation of these proteins. As this field expands into new areas such as computational biology, cellular lipid mapping, single molecule imaging, and lipidomics, there is an urgent need to integrate technologies to detail the molecular architecture and mechanisms of lipid signalling. This review surveys emerging cellular and in vitro approaches for studying protein–lipid interactions and provides perspective on how integration of methodologies directs the future development of the field. PMID:22327461

Scott, Jordan L.; Musselman, Catherine A.; Adu-Gyamfi, Emmanuel; Kutateladze, Tatiana G.

2013-01-01

373

Polar Lipids of Burkholderia pseudomallei Induce Different Host Immune Responses  

PubMed Central

Melioidosis is a disease in tropical and subtropical regions of the world that is caused by Burkholderia pseudomallei. In endemic regions the disease occurs primarily in humans and goats. In the present study, we used the goat as a model to dissect the polar lipids of B. pseudomallei to identify lipid molecules that could be used for adjuvants/vaccines or as diagnostic tools. We showed that the lipidome of B. pseudomallei and its fractions contain several polar lipids with the capacity to elicit different immune responses in goats, namely rhamnolipids and ornithine lipids which induced IFN-?, whereas phospholipids and an undefined polar lipid induced strong IL-10 secretion in CD4+ T cells. Autologous T cells co-cultured with caprine dendritic cells (cDCs) and polar lipids of B. pseudomallei proliferated and up-regulated the expression of CD25 (IL-2 receptor) molecules. Furthermore, we demonstrated that polar lipids were able to up-regulate CD1w2 antigen expression in cDCs derived from peripheral blood monocytes. Interestingly, the same polar lipids had only little effect on the expression of MHC class II DR antigens in the same caprine dendritic cells. Finally, antibody blocking of the CD1w2 molecules on cDCs resulted in decreased expression for IFN-? by CD4+ T cells. Altogether, these results showed that polar lipids of B. pseudomallei are recognized by the caprine immune system and that their recognition is primarily mediated by the CD1 antigen cluster. PMID:24260378

Gonzalez-Juarrero, Mercedes; Mima, Naoko; Trunck, Lily A.; Schweizer, Herbert P.; Bowen, Richard A.; Dascher, Kyle; Mwangi, Waithaka; Eckstein, Torsten M.

2013-01-01

374

Lipases as biocatalysts for the synthesis of structured lipids.  

PubMed

Structured lipids (SL) are broadly referred to as modified or synthetic oils and fats or lipids with functional or pharmaceutical applications. Some structured lipids, such as triglycerides that contain both long-chain (mainly essential) fatty acids and medium- or short-chain fatty acids and also artificial products that mimic the structure of natural materials, namely human milk fat substitutes and cocoa butter equivalents, have been discussed. Further, other modified or synthetic lipids, such as structured phospholipids and synthetic phenolic lipids are also included in this chapter. For all the products described in this chapter, enzymatic production in industry has been already conducted in one way or another. Cocoa butter equivalents, healthy oil containing medium-chain fatty acids, phosphatidyl serine, and phenol lipids from enzyme technology have been reported for commercial operation. As the demand for better quality functional lipids is increasing, the production of structured lipids becomes an interesting area. Thus, in this chapter we have discussed latest developments as well as present industrial situation of all commercially important structured lipids. PMID:22426731

Jala, Ram Chandra Reddy; Hu, Peng; Yang, Tiankui; Jiang, Yuanrong; Zheng, Yan; Xu, Xuebing

2012-01-01

375

Membrane lipids: where they are and how they behave  

PubMed Central

Throughout the biological world, a 30 Å hydrophobic film typically delimits the environments that serve as the margin between life and death for individual cells. Biochemical and biophysical findings have provided a detailed model of the composition and structure of membranes, which includes levels of dynamic organization both across the lipid bilayer (lipid asymmetry) and in the lateral dimension (lipid domains) of membranes. How do cells apply anabolic and catabolic enzymes, translocases and transporters, plus the intrinsic physical phase behaviour of lipids and their interactions with membrane proteins, to create the unique compositions and multiple functionalities of their individual membranes? PMID:18216768

van Meer, Gerrit; Voelker, Dennis R.; Feigenson, Gerald W.

2009-01-01

376

Lipid profile characterization of wastewaters from different origins.  

PubMed

Lipids in wastewaters are potential raw material for renewable diesel, but may complicate biological treatment of wastewaters. The lipid composition of palm oil mill effluent (POME), chemithermomechanical pulp mill (CTMP) wastewater and municipal wastewater (MWW) was studied with a combination of thin-layer chromatography and nuclear magnetic resonance. Gravimetrically determined content of extracted lipids from the solids of POME and CTMP wastewater were 8.4 ± 1.2 g/L (19.6 ± 0.8% of dry weight) and 0.17-0.23 g/L (12.4-18.5%), respectively, while MWW contained 0.021 ± 0.002 g/L (9.3 ± 1.4%) of lipids. All lipid extracts contained mono-, di- and triacylglycerols (TAGs) and free fatty acids (FFAs). In POME, lipids were mostly TAGs (11.5 ± 0.2 ?mol/10 mg of lipid extract). In CTMP and MWW lipid composition was more diverse than in POME containing also sterol derivatives and fatty acid methyl esters and the main lipids were FFAs. PMID:24334903

Efimova, E; Marjakangas, J M; Lakaniemi, A-M; Koskinen, P E P; Puhakka, J A

2013-01-01

377

Role of ABC transporters in lipid transport and human disease  

PubMed Central

Almost half of the 48 human ATP binding cassette (ABC) transporter proteins are thought to facilitate the ATP-dependent translocation of lipids or lipid-related compounds. Such substrates include cholesterol, plant sterols, bile acids, phospholipids and sphingolipids. Mutations in a substantial number of the 48 human ABC transporters have been linked to human disease. Indeed the finding that 12 diseases have been associated with abnormal lipid transport and/or homeostasis, demonstrates the importance of this family of transporters in cell physiology. This review highlights the role of ABC transporters in lipid transport and movement, in addition to discussing their roles in cellular homeostasis and inherited disorders. PMID:23415156

Tarling, Elizabeth J.; de Aguiar Vallim, Thomas Q.; Edwards, Peter A.

2013-01-01

378

Lipid digestion and effects of diets rich in lipids on carbohydrate and nitrogen digestion. A review *  

E-print Network

-Genès-Champanelle, France This review deals with ruminal metabolism and intestinal digestion of lipids, and with the conse bac- teria. Ruminal degradation of starch is not mod- ified. Disturbances of ruminal carbohydrate rich in starch. Ruminal nitrogen degradation, mea- sured in situ and in vivo, and synthesis, mea- sured

Boyer, Edmond

379

Lipid Peroxidation and Modification of Lipid Composition in an Endothelial Cell Model of Ischemia and Reperfusion  

Microsoft Academic Search

Among the changes that accompany the development of ischemia are alterations in the composition and turnover of membrane phospholipids. To study these effects, a cell culture model was developed to facilitate accurate measurements of lipids over varying intervals of ischemia and reperfusion (I\\/R). In order to mimic ischemia, rabbit aortic endothelial cells were grown to confluency on collagen coated beads

Laurie L. McLeod; Alex Sevanian

1997-01-01

380

The Role of Diglycosyl Lipids in Photosynthesis and Membrane Lipid Homeostasis in Arabidopsis1[OA  

PubMed Central

The galactolipid digalactosyldiacylglycerol (DGD) is an abundant thylakoid lipid in chloroplasts. The introduction of the bacterial lipid glucosylgalactosyldiacylglycerol (GGD) from Chloroflexus aurantiacus into the DGD-deficient Arabidopsis (Arabidopsis thaliana) dgd1 mutant was previously shown to result in complementation of growth, but photosynthetic efficiency was only partially restored. Here, we demonstrate that GGD accumulation in the double mutant dgd1dgd2, which is totally devoid of DGD, also complements growth at normal and high-light conditions, but photosynthetic efficiency in the GGD-containing dgd1dgd2 line remains decreased. This is attributable to an increased susceptibility of photosystem II to photodamage, resulting in reduced photosystem II accumulation already at normal light intensities. The chloroplasts of dgd1 and dgd1dgd2 show alterations in thylakoid ultrastructure, a phenotype that is restored in the GGD-containing lines. These data suggest that the strong growth retardation of the DGD-deficient lines dgd1 and dgd1dgd2 can be primarily attributed to a decreased capacity for chloroplast membrane assembly and proliferation and, to a smaller extent, to photosynthetic deficiency. During phosphate limitation, GGD increases in plastidial and extraplastidial membranes of the transgenic lines to an extent similar to that of DGD in the wild type, indicating that synthesis and transport of the bacterial lipid (GGD) and of the authentic plant lipid (DGD) are subject to the same mechanisms of regulation. PMID:19403724

Holzl, Georg; Witt, Sandra; Gaude, Nicole; Melzer, Michael; Schottler, Mark Aurel; Dormann, Peter

2009-01-01

381

Response of pigeon guillemots to variable abundance of high-lipid and low-lipid prey  

Microsoft Academic Search

Populations of the pigeon guillemot (Cepphus columba) and other piscivores have been in decline for several decades in the Gulf of Alaska and Bering Sea, and a decline in abundance of lipid-rich schooling fishes is hypothesized as the major cause. We tested this hypothesis by studying the breeding biology of pigeon guillemots during 1995-1999 while simultaneously measuring prey abundance with

Michael A. Litzow; John F. Piatt; Alexander K. Prichard; Daniel D. Roby

2002-01-01

382

Lipid Lowering Effect of Punica granatum L. Peel in High Lipid Diet Fed Male Rats  

PubMed Central

Many herbal medicines have been recommended for the treatment of dyslipidemia. The antilipidemic effect of hydroethanolic extract of pomegranate peel (Punica granatum L.) was investigated in high lipid diet fed male rats. Intraperitoneally administration of pomegranate peel extract (50, 100, 200, and 300?mg/kg body weight) for 23 days on the levels of serum cholesterol, triglycerides, LDL, HDL, alkaline phosphatase (AP), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) in high lipid diet fed male rats was evaluated. Treatment of pomegranate extract decreased body weight in treated rats, significantly. Administration of the plant extract significantly decreased serum total cholesterol, triglycerides, LDL-C, alkaline phosphatise, AST, and ALT levels, whereas it increased serum HDL-C in high lipid diet fed rats in comparison to saline control group. Also, histopathological study showed that treatment of pomegranate peel extract attenuates liver damage in high lipid diet fed rats in comparison to saline group. It is concluded that the plant should be considered as an excellent candidate for future studies on dyslipidemia. PMID:25295067

Sadeghipour, Alireza; Ilchizadeh Kavgani, Ali; Ghahramani, Reza; Shahabzadeh, Saleh; Anissian, Ali

2014-01-01

383

LC/MS lipid profiling from human serum: a new method for global lipid extraction.  

PubMed

Over the last decade, technological advances have improved the sensitivity and selectivity of LC/MS analyzers, providing very efficient tools for lipidomics research. In particular, the nine lipid classes that constitute 99 % of the human serum lipidome (sterols, cholesteryl esters, phosphocholines, phosphoethanolamines, sphingomyelins, triacylglycerols, fatty acids, lysophosphocholines, and diacylglycerols) can be easily detected. However, until today there has not been a unique technique for sample preparation that provides a satisfactory recovery for all of these nine classes together. In this work, we have developed and validated a new one-phase extraction (OPE) method that overcomes this limitation. This method was also compared with the gold standard lipid extraction methods such as Folch, Bligh & Dyer, and recently developed methods with methanol and methyl-tert-butyl ether. Results demonstrate that the mixture of methanol/chloroform/MTBE (MMC) provides a recovery very close to 100 % for all nine lipid classes of the human serum investigated. For this extraction method, 100 ?L of human serum is incubated with 2 mL of the solvents mixture, then vortexed and centrifuged. For its simplicity of execution, rapidity, reproducibility, and the reduced volume of sample required, this method opens the door to the use of human serum lipid profiling for large-scale applications in scientific research and clinical trials. PMID:25381612

Pellegrino, Roberto Maria; Di Veroli, Alessandra; Valeri, Aurora; Goracci, Laura; Cruciani, Gabriele

2014-12-01

384

Micrometric segregation of fluorescent membrane lipids: relevance for endogenous lipids and biogenesis in erythrocytes[S  

PubMed Central

Micrometric membrane lipid segregation is controversial. We addressed this issue in attached erythrocytes and found that fluorescent boron dipyrromethene (BODIPY) analogs of glycosphingolipids (GSLs) [glucosylceramide (BODIPY-GlcCer) and monosialotetrahexosylganglioside (GM1BODIPY)], sphingomyelin (BODIPY-SM), and phosphatidylcholine (BODIPY-PC inserted into the plasma membrane spontaneously gathered into distinct submicrometric domains. GM1BODIPY domains colocalized with endogenous GM1 labeled by cholera toxin. All BODIPY-lipid domains disappeared upon erythrocyte stretching, indicating control by membrane tension. Minor cholesterol depletion suppressed BODIPY-SM and BODIPY-PC but preserved BODIPY-GlcCer domains. Each type of domain exchanged constituents but assumed fixed positions, suggesting self-clustering and anchorage to spectrin. Domains showed differential association with 4.1R versus ankyrin complexes upon antibody patching. BODIPY-lipid domains also responded differentially to uncoupling at 4.1R complexes [protein kinase C (PKC) activation] and ankyrin complexes (in spherocytosis, a membrane fragility disease). These data point to micrometric compartmentation of polar BODIPY-lipids modulated by membrane tension, cholesterol, and differential association to the two nonredundant membrane:spectrin anchorage complexes. Micrometric compartmentation might play a role in erythrocyte membrane deformability and fragility. PMID:23322884

D'Auria, Ludovic; Fenaux, Marisa; Aleksandrowicz, Paulina; Van Der Smissen, Patrick; Chantrain, Christophe; Vermylen, Christiane; Vikkula, Miikka; Courtoy, Pierre J.; Tyteca, Donatienne

2013-01-01

385

Lipid peroxidation and water penetration in lipid bilayers: a W-band EPR study.  

PubMed

Lipid peroxidation plays a key role in the alteration of cell membrane's properties. Here we used as model systems multilamellar vesicles (MLVs) made of the first two products in the oxidative cascade of linoleoyl lecithin, namely 1-palmitoyl-2-(13-hydroperoxy-9,11-octadecanedienoyl)-lecithin (HpPLPC) and 1-palmitoyl-2-(13-hydroxy-9,11-octadecanedienoyl)-lecithin (OHPLPC), exhibiting a hydroperoxide or a hydroxy group at position 13, respectively. The two oxidized lipids were used either pure or in a 1:1 molar ratio mixture with untreated 1-palmitoyl-2-linoleoyl-lecithin (PLPC). The model membranes were doped with spin-labeled lipids to study bilayer alterations by electron paramagnetic resonance (EPR) spectroscopy. Two different spin-labeled lipids were used, bearing the doxyl ring at position (n) 5 or 16: ?-palmitoyl-?-(n-doxylstearoyl)-lecithin (n-DSPPC) and n-doxylstearic acid (n-DSA). Small changes in the acyl chain order in the sub-polar region and at the methyl-terminal induced by lipid peroxidation were detected by X-band EPR. Concomitantly, the polarity and proticity of the membrane bilayer in those regions were investigated at W band in frozen samples. Analysis of the g(xx) and A(zz) parameters revealed that OHPLPC, but mostly HpPLPC, induced a measurable increase in polarity and H-bonding propensity in the central region of the bilayer. Molecular dynamics simulation performed on 16-DSA in the PLPC-HpPLPC bilayer revealed that water molecules are statistically favored with respect to the hydroperoxide groups to interact with the nitroxide at the methyl-terminal, confirming that the H-bonds experimentally observed are due to increased water penetration in the bilayer. The EPR and MD data on model membranes demonstrate that cell membrane damage by oxidative stress cause alteration of water penetration in the bilayer. PMID:23036933

Conte, Elena; Megli, Francesco Maria; Khandelia, Himanshu; Jeschke, Gunnar; Bordignon, Enrica

2013-02-01

386

Density imbalances and free energy of lipid transfer in supported lipid bilayers  

NASA Astrophysics Data System (ADS)

Supported lipid bilayers are an abundant research platform for understanding the behavior of real cell membranes as they allow for additional mechanical stability and at the same time have a fundamental structure approximating cell membranes. However, in computer simulations these systems have been studied only rarely up to now. An important property, which cannot be easily determined by molecular dynamics or experiments, is the unsymmetrical density profiles of bilayer leaflets (density imbalance) inflicted on the membrane by the support. This imbalance in the leaflets composition has consequences for membrane structure and phase behavior, and therefore we need to understand it in detail. The free energy can be used to determine the equilibrium structure of a given system. We employ an umbrella sampling approach to obtain the free energy of a lipid crossing the membrane (i.e., lipid flip-flop) as a function of bilayer composition and hence the equilibrium composition of the supported bilayers. In this paper, we use a variant of the coarse-grained Martini model. The results of the free energy calculation lead to a 5% higher density in the proximal leaflet. Recent data obtained by large scale modeling using a water free model suggested that the proximal leaflet had 3.2% more lipids than the distal leaflet [Hoopes et al., J. Chem. Phys. 129, 175102 (2008)]. Our findings are in line with these results. We compare results of the free energy of transport obtained by pulling the lipid across the membrane in different ways. There are small quantitative differences, but the overall picture is consistent. We additionally characterize the intermediate states, which determine the barrier height and therefore the rate of translocation. Calculations on unsupported bilayers are used to validate the approach and to determine the barrier to flip-flop in a free membrane.

Xing, Chenyue; Faller, Roland

2009-11-01

387

Lipid composition of beef brain, beef liver, and the sea anemone: Two approaches to quantitative fractionation of complex lipid mixtures  

Microsoft Academic Search

Two new schemes for fractionation of complex lipid mixtures are presented. Their use for the study of lipids of beef brain,\\u000a beef liver, and the sea anemone are described. Apparatus and techniques for working in an inert atmosphere, evaporation of\\u000a solutions in the cold under nitrogen, use of infrared spectroscopy for examination of lipids and their hydrolysis products,\\u000a preparation and

George Rouser; Gene Kritchevsky; Dorothy Heller; Ellen Lieber

1963-01-01

388

The lipid bilayer concept and its experimental realization: from soap bubbles, kitchen sink, to bilayer lipid membranes  

Microsoft Academic Search

The inspiration for lipid bilayer research, without question, comes from the biological world. Although self-assembled bilayer lipid membranes (BLMs) in vitro, were first reported in 1961, experimental scientists have been dealing with BLM-type interfacial adsorption phenomena since Robert Hooke’s time (1672). BLMs (of planar lipid bilayers) have been used in a number of applications ranging from basic membrane biophysics including

H. Ti Tien; Angelica L Ottova

2001-01-01

389

Lipid changes after leaf wounding in Arabidopsis thaliana: expanded lipidomic data form the basis for lipid co-occurrence analysis.  

PubMed

A direct-infusion electrospray ionization triple-quadrupole mass spectrometry method with multiple reaction monitoring (MRM) was employed to measure 264 lipid analytes extracted from leaves of Arabidopsis thaliana subjected to mechanical wounding. The method provided precise measurements with an average coefficient of variation of 6.1%. Lipid classes analyzed comprised galactolipids and phospholipids (including monoacyl molecular species, molecular species with oxidized acyl chains, phosphatidic acids (PAs)), tri- and tetra-galactosyldiacylglycerols (TrGDGs and TeGDGs), head-group-acylated galactolipids, and head-group-acylated phosphatidylglycerol (acPG), sulfoquinovosyldiacylglycerols (SQDGs), sphingolipids, di- and tri-acylglycerols (DAGs and TAGs), and sterol derivatives. Of the 264 lipid analytes, 254 changed significantly in response to wounding. In general, levels of structural lipids decreased, whereas monoacyl molecular species, galactolipids and phosphatidylglycerols (PGs) with oxidized fatty acyl chains, PAs, TrGDGs, TeGDGs, TAGs, head-group-acylated galactolipids, acPG, and some sterol derivatives increased, many transiently. The observed changes are consistent with activation of lipid oxidizing, hydrolyzing, glycosylating, and acylating activities in the wounding response. Correlation analysis of the levels of lipid analytes across individual control and treated plants was used to construct a lipid dendrogram and to define clusters and sub-clusters of lipid analytes, each composed of a group of lipids which occurred in a coordinated manner. Current knowledge of metabolism supports the notion that observed sub-clusters comprise lipids generated by a common enzyme and/or metabolically downstream of a common enzyme. This work demonstrates that co-occurrence analysis, based on correlation of lipid levels among plants, is a powerful approach to defining lipids generated in vivo by a common enzymatic pathway. PMID:25200898

Vu, Hieu Sy; Shiva, Sunitha; Roth, Mary R; Tamura, Pamela; Zheng, Lianqing; Li, Maoyin; Sarowar, Sujon; Honey, Samuel; McEllhiney, Dedan; Hinkes, Paul; Seib, Lawrence; Williams, Todd D; Gadbury, Gary; Wang, Xuemin; Shah, Jyoti; Welti, Ruth

2014-11-01

390

Apolipoprotein E: from lipid transport to neurobiology  

PubMed Central

Apolipoprotein (apo) E has a storied history as a lipid transport protein. The integral association between cholesterol homeostasis and lipoprotein clearance from circulation are intimately related to apoE's function as a ligand for cell surface receptors of the low density lipoprotein receptor family. The receptor binding properties of apoE are strongly influenced by isoform specific amino acid differences as well as the lipidation state of the protein. As understanding of apoE as a structural component of circulating plasma lipoproteins has evolved, exciting developments in neurobiology have revitalized interest in apoE. The strong and enduring correlation between the apoE4 isoform and age of onset and increased risk of Alzheimer's disease has catapulted apoE to the forefront of neurobiology. Using genetic tools generated for study of apoE lipoprotein metabolism, transgenic “knock-in” and gene-disrupted mice are now favored models for study of its role in a variety of neurodegenerative diseases. Key structural knowledge of apoE and isoform specific differences is driving research activity designed to elucidate how a single amino acid change can manifest such profoundly significant pathological consequences. This review describes apoE through a lens of structure-based knowledge that leads to hypotheses that attempt to explain the functions of apoE and isoform specific effects relating to disease mechanism. PMID:20854843

Hauser, Paul S.; Narayanaswami, Vasanthy; Ryan, Robert O.

2010-01-01

391

Alcohol's Effects on Lipid Bilayer Properties  

PubMed Central

Alcohols are known modulators of lipid bilayer properties. Their biological effects have long been attributed to their bilayer-modifying effects, but alcohols can also alter protein function through direct protein interactions. This raises the question: Do alcohol's biological actions result predominantly from direct protein-alcohol interactions or from general changes in the membrane properties? The efficacy of alcohols of various chain lengths tends to exhibit a so-called cutoff effect (i.e., increasing potency with increased chain length, which that eventually levels off). The cutoff varies depending on the assay, and numerous mechanisms have been proposed such as: limited size of the alcohol-protein interaction site, limited alcohol solubility, and a chain-length-dependent lipid bilayer-alcohol interaction. To address these issues, we determined the bilayer-modifying potency of 27 aliphatic alcohols using a gramicidin-based fluorescence assay. All of the alcohols tested (with chain lengths of 1–16 carbons) alter the bilayer properties, as sensed by a bilayer-spanning channel. The bilayer-modifying potency of the short-chain alcohols scales linearly with their bilayer partitioning; the potency tapers off at higher chain lengths, and eventually changes sign for the longest-chain alcohols, demonstrating an alcohol cutoff effect in a system that has no alcohol-binding pocket. PMID:21843475

Ingolfsson, Helgi I.; Andersen, Olaf S.

2011-01-01

392

Lipid peroxidation in judoists using oral contraceptives.  

PubMed

12 female judoists using oral contraceptives (OCU) containing 0.03 mg ethinylestradiol and 3 mg drospirenone for 20 ± 12 months (mean ± SD) were compared with a control group of 14 judoist noncontraceptive users (NCU) in order to evaluate resting (T1) and postexercise (T2) lipid peroxidation (LPO) and antioxidant parameters. Data were collected 20 min before and 10 min after a morning session of judo training and included determination of lag phase (Lp) before free radical-induced oxidation, glutathione peroxidase (GPx), ?-tocopherol, retinol, and oxidative stress markers related to LPO. Significantly higher resting oxidative stress (+125.8 and +165.2% for malondialdehyde and lipid peroxides, respectively) and lower values of Lp and GPx (-23.4 and -12.1%, respectively) were observed in the OCU compared with NCU. The judo training session induced an increase in plasma LPO whatever the treatment. We noted significant increases in Lp (+14.7%; p<0.05 vs. preexercise) and GPx (22.1%; p<0.05 vs. preexercise) only in the NCU group. We suggest that a judo training session favourably altered some antioxidants in NCU but not in OCU. As excessive oxidative stress is linked to the development of several chronic diseases, the use of agents to reduce antioxidants may be reasonable in OCU. PMID:22562736

Massart, A; Portier, H; Rosado, F; Toumi, H; Filaire, E

2012-10-01

393

Face the Fats The Biochemistry of Lipids  

NSDL National Science Digital Library

This clicker case introduces students to the biochemistry of lipids through the story of Pete, a college student who begins to consider his nutritional fat intake after watching a commercial for the cholesterol-lowering drug Vytorin. In this case, students learn to differentiate the chemical composition of steroids, phospholipids, and fats as well as how lipids affect our health, both in positive and negative ways. Additionally, students learn how trans fats are manufactured and why they can have negative health side-effects. The case is designed for use in an introductory biology course either for science majors or non-majors. It could potentially be further modified for use in an upper-level biochemistry or cell biology class. The case is called a clicker case because it combines the use of PowerPoint slides (~3.74MB) and student response systems ("clickers") with a case storyline and questions. The case could be modifed however for use without these technologies.

Rice, Nancy A.

2011-01-01

394

Metabolic syndrome: soybean foods and serum lipids.  

PubMed Central

Metabolic syndrome is a cluster of coronary heart disease (CHD) risk factors of which central obesity, insulin resistance, increased triglycerides/decreased HDL cholesterol, and hypertension are major cardiovascular risk factors. The educational objectives of this review are to describe hypocholesteromic effects from soybean foods. Early Italian observations indicated that isolated soy protein lowered total cholesterol, especially the LDL component, in humans with elevated serum lipids. Whole soybeans, with their major phytoestrogen inflavones (genistein, daidzein, and glycetin) intact, are known to decrease both total and LDL cholesterol. Major early reviews, meta-analyses, and clinical trials in hyperlipidemic humans indicate a predictable range of decreases in serum lipids: total cholesterol (10-19%), LDL cholesterol (14-20%), and triglycerides (8-14%). Recent, large, randomized trials in postmenopausal women indicated that a soy protein component induces significant increases in HDL cholesterol. Therapy for metabolic syndrome must first be patient education, especially for predominant U.S. minority groups (Afro-, Latino-, and Native Americans). The four major preventive health educational facts necessary to reduce CHD/metabolic syndrome must now recognize that whole soybeans are abundant sources of: 1) vegetable protein, 2) high soluble fiber content, 3) virtual absence of saturated fat, though high in polyunsaturated fats, and 4) major phytoestrogens. PMID:15303407

Merritt, John C.

2004-01-01

395

Preservation of nanostructured lipid carriers (NLC).  

PubMed

Due to their positive features (e.g., increased penetration of actives, re-enforcement of the lipid barrier and increase in skin hydration), nanostructured lipid carriers (NLC) are used in many dermal formulations. These formulations require preservation, and preservatives can impair the physical stability of disperse systems. Therefore, in this study, the influence of preservatives on the physical stability of Q10-loaded NLC was investigated using 11 different preservative mixtures. Whereas for nanosuspensions, only a limited number of preservatives are known from the literature not affecting their physical stability, a surprisingly high number of seven preservatives could be identified to be suitable for the preservation of NLC dispersions. For Q10-loaded NLC, Hydrolite 5 proved to be the best preservative, as it was found surprisingly to stabilize the NLC dispersion. Based on the data, a preservative classification system is suggested and a mechanistic model describing six key parameters affecting the physical stability of NLC could be developed. As most suitable characterization method to screen for suitable preservatives, light microscopy was identified. By being a simple, fast and cost efficient method, even extensive preservative screening studies can be performed very efficiently. PMID:20452422

Obeidat, Wasfy M; Schwabe, Kay; Müller, Rainer H; Keck, Cornelia M

2010-09-01

396

Cellular palmitoylation and trafficking of lipidated peptides  

PubMed Central

Many important signaling proteins require the posttranslational addition of fatty acid chains for their proper subcellular localization and function. One such modification is the addition of palmitoyl moieties by enzymes known as palmitoyl acyltransferases (PATs). Substrates for PATs include C-terminally farnesylated proteins, such as H- and N-Ras, as well as N-terminally myristoylated proteins, such as many Src-related tyrosine kinases. The molecular and biochemical characterization of PATs has been hindered by difficulties in developing effective methods for the analysis of PAT activity. In this study, we describe the use of cell-permeable, fluorescently labeled lipidated peptides that mimic the PAT recognition domains of farnesylated and myristoylated proteins. These PAT substrate mimetics are accumulated by SKOV3 cells in a saturable and time-dependent manner. Although both peptides are rapidly palmitoylated, the SKOV3 cells have a greater capacity to palmitoylate the myristoylated peptide than the farnesylated peptide. Confocal microscopy indicated that the palmitoylated peptides colocalized with Golgi and plasma membrane markers, whereas the corresponding nonpalmitoylatable peptides accumulated in the Golgi but did not traffic to the plasma membrane. Overall, these studies indicate that the lipidated peptides provide useful cellular probes for quantitative and compartmentalization studies of protein palmitoylation in intact cells. PMID:17525474

Draper, Jeremiah M.; Xia, Zuping; Smith, Charles D.

2010-01-01

397

Cadmium induced lipid peroxidation in kidney function.  

PubMed

Since the kidney is the main target organ for many metals including cadmium, the generation of the products of lipid peroxidation due to accumulation of these toxic metals in the kidney may have importance in the mechanism of their nephrotoxicity. In order to test this hypothesis, we carried out an experimental study in rats. The functions and the levels of tiobarbituric acid reactive substances (TBARS) of the kidney were investigated in animals receiving 15 micrograms/ml aqueous Cd solution for 30 days. Due to cadmium accumulation in kidney cortex, the ratio of Cd/Zn increased significantly and this increase was associated with elevated TBARS in both renal cortex and medulla. The content of TBARS in renal cortex rose from 211.6 +/- 64.2 to 303.4 +/- 46.4 nmol/g protein (p<0.01) and GFR decreased to 390.5 +/- 109.4 from 1008.7 +/- 4.8 microliters/min (p<0.01) in cadmium exposed animals. Daily coadministration of selenium, vitamins A, C, E did not reverse the adverse effect of cadmium on kidney function, despite the significant decrease in cortex TBARS levels (p<0.01). In conclusion, these data suggest to us that lipid peroxidation assessed by TBA test may not be the only mechanism in cadmium induced nephrotoxicity. PMID:8736039

Sentürk, U K; Oner, G; Izgüt-Uysal, V M

1994-01-01

398

Cognition, dopamine and bioactive lipids in schizophrenia  

PubMed Central

Schizophrenia is a remarkably complex disorder with a multitude of behavioral and biological perturbations. Cognitive deficits are a core feature of this disorder, and involve abnormalities across multiple domains, including memory, attention, and perception. The complexity of this debilitating illness has led to a view that the key to unraveling its pathophysiology lies in deconstructing the clinically-defined syndrome into pathophysiologically distinct intermediate phenotypes. Accumulating evidence suggests that one of these intermediate phenotypes may involve phospholipid signaling abnormalities, particularly in relation to arachidonic acid (AA). Our data show relationships between levels of AA and performance on tests of cognition for schizophrenia patients, with defects in AA signaling associated with deficits in cognition. Moreover, dopamine may moderate these relationships between AA and cognition. Taken together, cognitive deficits, dopaminergic neurotransmission, and bioactive lipids have emerged as related features of schizophrenia. Existing treatment options for cognitive deficits in schizophrenia do not specifically target lipid-derived signaling pathways; understanding these processes could inform efforts to identify novel targets for treatment innovation. PMID:21196378

Condray, Ruth; Yao, Jeffrey K.

2011-01-01

399

Tryptophan orientation in model lipid membranes  

SciTech Connect

Tryptophans in membrane proteins display strong preference for the lipid membrane interface and are important for anchoring proteins at the proper longitudinal level. Linear dichroism spectroscopy on indoles in shear-deformed liposomes has been used to show that this positioning is accompanied by an intrinsically adopted orientation, also observed for tryptophans in membrane-bound peptides. Similarities in orientation of different indoles suggest that tryptophan will adopt this orientation independent of the protein it is part of. From the orientation of indole electronic transition moments L{sub a}, L{sub b} and B{sub b}, a binding model is proposed where the indole long axis is {approx}60-65 deg. from the membrane normal and the indole plane is at an oblique angle. We propose that dipole-dipole interactions and steric constraints in the membrane hydrocarbon region determine positioning and orientation of tryptophans whereas hydrogen bonding and cation-{pi} interactions with lipid head-groups, though contributing to the membrane affinity of indoles, are less important.

Esbjoerner, Elin K. [Department of Chemical and Biological Engineering/Physical Chemistry, Chalmers University of Technology, Kemivaegen 10, S-412 96 Gothenburg (Sweden)], E-mail: eline@chalmers.se; Caesar, Christina E.B.; Albinsson, Bo; Lincoln, Per [Department of Chemical and Biological Engineering/Physical Chemistry, Chalmers University of Technology, Kemivaegen 10, S-412 96 Gothenburg (Sweden); Norden, Bengt [Department of Chemical and Biological Engineering/Physical Chemistry, Chalmers University of Technology, Kemivaegen 10, S-412 96 Gothenburg (Sweden)], E-mail: norden@chalmers.se

2007-09-28

400

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

PubMed Central

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

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

2013-01-01

401

Cationic Cell-Penetrating Peptide Binds to Planar Lipid Bilayers Containing Negatively Charged Lipids but does not Induce Conductive Pores  

PubMed Central

Using a cation-selective gramicidin A channel as a sensor of the membrane surface charge, we studied interactions of oligoarginine peptide R9C, a prototype cationic cell-penetrating peptide (CPP), with planar lipid membranes. We have found that R9C sorption to the membrane depends strongly on its lipid composition from virtually nonexistent for membranes made of uncharged lipids to very pronounced for membranes containing negatively charged lipids, with charge overcompensation at R9C concentrations exceeding 1 ?M. The sorption was reversible as it was removed by addition of polyanionic dextran sulfate to the membrane bathing solution. No membrane poration activity of R9C (as would be manifested by increased bilayer conductance) was detected in the charged or neutral membranes, including those with asymmetric negative/neutral and negative/positive lipid leaflets. We conclude that interaction of R9C with planar lipid bilayers does not involve pore formation in all studied lipid combinations up to 20 ?M peptide concentration. However, R9C induces leakage of negatively charged but not neutral liposomes in a process that involves lipid mixing between liposomes. Our findings suggest that direct traversing of CPPs through the uncharged outer leaflet of the plasma membrane bilayer is unlikely and that permeabilization necessarily involves both anionic lipids and CPP-dependent fusion between opposing membranes. PMID:23663836

Gurnev, Philip A.; Yang, Sung-Tae; Melikov, Kamran C.; Chernomordik, Leonid V.; Bezrukov, Sergey M.

2013-01-01

402

Lamellar cationic lipid-DNA complexes from lipids with a strong preference for planar geometry: A Minimal Electrostatic Model.  

PubMed

We formulate and analyze a minimal model, based on condensation theory, of the lamellar cationic lipid (CL)-DNA complex of alternately charged lipid bilayers and DNA monolayers in a salt solution. Each lipid bilayer, composed by a random mixture of cationic and neutral lipids, is assumed to be a rigid uniformly charged plane. Each DNA monolayer, located between two lipid bilayers, is formed by the same number of parallel DNAs with a uniform separation distance. For the electrostatic calculation, the model lipoplex is collapsed to a single plane with charge density equal to the net lipid and DNA charge. The free energy difference between the lamellar lipoplex and a reference state of the same number of free lipid bilayers and free DNAs, is calculated as a function of the fraction of CLs, of the ratio of the number of CL charges to the number of negative charges of the DNA phosphates, and of the total number of planes. At the isoelectric point the free energy difference is minimal. The complex formation, already favoured by the decrease of the electrostatic charging free energy, is driven further by the free energy gain due to the release of counterions from the DNAs and from the lipid bilayers, if strongly charged. This minimal model compares well with experiment for lipids having a strong preference for planar geometry and with major features of more detailed models of the lipoplex. © 2014 Wiley Periodicals, Inc. Biopolymers 101: 1114-1128, 2014. PMID:24931742

Perico, Angelo; Manning, Gerald S

2014-11-01

403

Lipid profiling by electrospray ionization tandem mass spectrometry and the identification of lipid phosphorylation by kinases in potato stolons  

PubMed Central

There is limited information about the involvement of lipids and esterified fatty acids in signaling pathways during plant development. The purpose of this study was to evaluate the lipid composition and molecular species of potato (Solanum tuberosum L., cv. Spunta) stolons and to identify phosphorylated lipids in the first two developmental stages of tuber formation. Lipid profiling was determined using ESI-MS/MS, a useful method for the determination of the biosynthesis and catabolism of lipids based on their fatty acid composition. The most prevalent compound identified in this study was phosphatidic acid (PA); digalactosyldiacylglycerol (DGDG) was the second most abundant compound. A 34:2 species was identified in PA, phosphatidylcholine (PC), phosphatidylinositol (PI), and phosphatidylethanolamine (PE). The identification of lipid phosphorylation by kinases was revealed by the presence of the phosphorylated lipids. PA was metabolized to diacylglycerol pyrophosphate (DGPP) by phosphatidic acid kinase (PAK). This work establishes a correlation between lipid fatty acid composition and lipid metabolism enzymes at the beginning of tuber formation and is the first report of PAK activity in the early events of potato tuber formation. PMID:22142228

Cenzano, Ana M.; Cantoro, Renata; Teresa Hernandez-Sotomayor, S. M.; Abdala, Guillermina I.; Racagni, Graciela E.

2013-01-01

404

Factors influencing particulate lipid production in the East Atlantic Ocean  

NASA Astrophysics Data System (ADS)

Extensive analyses of particulate lipids and lipid classes were conducted to gain insight into lipid production and related factors along the biogeochemical provinces of the Eastern Atlantic Ocean. Data are supported by particulate organic carbon (POC), chlorophyll a (Chl a), phaeopigments, Chl a concentrations and carbon content of eukaryotic micro-, nano- and picophytoplankton, including cell abundances for the latter two and for cyanobacteria and prokaryotic heterotrophs. We focused on the productive ocean surface (2 m depth and deep Chl a maximum (DCM). Samples from the deep ocean provided information about the relative reactivity and preservation potential of particular lipid classes. Surface and DCM particulate lipid concentrations (3.5-29.4 ?g L-1) were higher than in samples from deep waters (3.2-9.3 ?g L-1) where an increased contribution to the POC pool was observed. The highest lipid concentrations were measured in high latitude temperate waters and in the North Atlantic Tropical Gyral Province (13-25°N). Factors responsible for the enhanced lipid synthesis in the eastern Atlantic appeared to be phytoplankton size (micro, nano, pico) and the low nutrient status with microphytoplankton having the most expressed influence in the surface and eukaryotic nano- and picophytoplankton in the DCM layer. Higher lipid to Chl a ratios suggest enhanced lipid biosynthesis in the nutrient poorer regions. The various lipid classes pointed to possible mechanisms of phytoplankton adaptation to the nutritional conditions. Thus, it is likely that adaptation comprises the replacement of membrane phospholipids by non-phosphorus containing glycolipids under low phosphorus conditions. The qualitative and quantitative lipid compositions revealed that phospholipids were the most degradable lipids, and their occurrence decreased with increasing depth. In contrast, wax esters, possibly originating from zooplankton, survived downward transport probably due to the fast sinking rate of particles (fecal pellets). The important contribution of glycolipids in deep waters reflected their relatively stable nature and degradation resistance. A lipid-based proxy for the lipid degradative state (Lipolysis Index) suggests that many lipid classes were quite resistant to degradation even in the deep ocean.

Gašparovi?, B.; Frka, S.; Koch, B. P.; Zhu, Z. Y.; Bracher, A.; Lechtenfeld, O. J.; Neogi, S. B.; Lara, R. J.; Kattner, G.

2014-07-01

405

Membrane Lipid Co-Aggregation with ?-Synuclein Fibrils  

PubMed Central

Amyloid deposits from several human diseases have been found to contain membrane lipids. Co-aggregation of lipids and amyloid proteins in amyloid aggregates, and the related extraction of lipids from cellular membranes, can influence structure and function in both the membrane and the formed amyloid deposit. Co-aggregation can therefore have important implications for the pathological consequences of amyloid formation. Still, very little is known about the mechanism behind co-aggregation and molecular structure in the formed aggregates. To address this, we study in vitro co-aggregation by incubating phospholipid model membranes with the Parkinson’s disease-associated protein, ?-synuclein, in monomeric form. After aggregation, we find spontaneous uptake of phospholipids from anionic model membranes into the amyloid fibrils. Phospholipid quantification, polarization transfer solid-state NMR and cryo-TEM together reveal co-aggregation of phospholipids and ?-synuclein in a saturable manner with a strong dependence on lipid composition. At low lipid to protein ratios, there is a close association of phospholipids to the fibril structure, which is apparent from reduced phospholipid mobility and morphological changes in fibril bundling. At higher lipid to protein ratios, additional vesicles adsorb along the fibrils. While interactions between lipids and amyloid-protein are generally discussed within the perspective of different protein species adsorbing to and perturbing the lipid membrane, the current work reveals amyloid formation in the presence of lipids as a co-aggregation process. The interaction leads to the formation of lipid-protein co-aggregates with distinct structure, dynamics and morphology compared to assemblies formed by either lipid or protein alone. PMID:24146972

Topgaard, Daniel; Linse, Sara; Sparr, Emma

2013-01-01

406

Lipid emulsions – Guidelines on Parenteral Nutrition, Chapter 6  

PubMed Central

The infusion of lipid emulsions allows a high energy supply, facilitates the prevention of high glucose infusion rates and is indispensable for the supply with essential fatty acids. The administration of lipid emulsions is recommended within ?7 days after starting PN (parenteral nutrition) to avoid deficiency of essential fatty acids. Low-fat PN with a high glucose intake increases the risk of hyperglycaemia. In parenterally fed patients with a tendency to hyperglycaemia, an increase in the lipid-glucose ratio should be considered. In critically ill patients the glucose infusion should not exceed 50% of energy intake. The use of lipid emulsions with a low phospholipid/triglyceride ratio is recommended and should be provided with the usual PN to prevent depletion of essential fatty acids, lower the risk of hyperglycaemia, and prevent hepatic steatosis. Biologically active vitamin E (?-tocopherol) should continuously be administered along with lipid emulsions to reduce lipid peroxidation. Parenteral lipids should provide about 25–40% of the parenteral non-protein energy supply. In certain situations (i.e. critically ill, respiratory insufficiency) a lipid intake of up to 50 or 60% of non-protein energy may be reasonable. The recommended daily dose for parenteral lipids in adults is 0.7–1.3 g triglycerides/kg body weight. Serum triglyceride concentrations should be monitored regularly with dosage reduction at levels >400 mg/dl (>4.6 mmol/l) and interruption of lipid infusion at levels >1000 mg/dl (>11.4 mmol/l). There is little evidence at this time that the choice of different available lipid emulsions affects clinical endpoints. PMID:20049078

Adolph, M.; Heller, A. R.; Koch, T.; Koletzko, B.; Kreymann, K. G.; Krohn, K.; Pscheidl, E.; Senkal, M.

2009-01-01

407

Regulation of LHCII aggregation by different thylakoid membrane lipids.  

PubMed

In the present study the influence of the lipid environment on the organization of the main light-harvesting complex of photosystem II (LHCII) was investigated by 77K fluorescence spectroscopy. Measurements were carried out with a lipid-depleted and highly aggregated LHCII which was supplemented with the different thylakoid membrane lipids. The results show that the thylakoid lipids are able to modulate the spectroscopic properties of the LHCII aggregates and that the extent of the lipid effect depends on both the lipid species and the lipid concentration. Addition of the neutral galactolipids monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) seems to induce a modification of the disorganized structures of the lipid-depleted LHCII and to support the aggregated state of the complex. In contrast, we found that the anionic lipids sulfoquinovosyldiacylglycerol (SQDG) and phosphatidylglycerol (PG) exert a strong disaggregating effect on the isolated LHCII. LHCII disaggregation was partly suppressed under a high proton concentration and in the presence of cations. The strongest suppression was visible at the lowest pH value (pH 5) and the highest Mg(2+) concentration (40 mM) used in the present study. This suggests that the negative charge of the anionic lipids in conjunction with negatively charged domains of the LHCII proteins is responsible for the disaggregation. Additional measurements by photon correlation spectroscopy and sucrose gradient centrifugation, which were used to gain information about the size and molecular mass of the LHCII aggregates, confirmed the results of the fluorescence spectroscopy. LHCII treated with MGDG and DGDG formed an increased number of aggregates with large particle sizes in the micromm-range, whereas the incubation with anionic lipids led to much smaller LHCII particles (around 40 nm in the case of PG) with a homogeneous distribution. PMID:21215252

Schaller, Susann; Latowski, Dariusz; Jemio?a-Rzemi?ska, Ma?gorzata; Dawood, Ayad; Wilhelm, Christian; Strza?ka, Kazimierz; Goss, Reimund

2011-03-01

408

Lipid Parameters - Significance in Patients with Endogenous Depression  

PubMed Central

Background: People are aware of the consequences of high serum lipid levels, specifically, total cholesterol. Awareness about harmful effects of very low levels of serum lipids is still lacking. Very low levels of serum lipids lead to psychological consequences. Objectives: The objective of this study was to show whether there was a significant relationship between serum lipid levels and depression. Material and Methods: Total 70 subjects were included in this study. 40 subjects suffering from depression as assessed with the help of clinical findings and Beck Depression Inventory (BDI) scores were included in the study group, while control group comprised of 30 normal subjects. Lipid profile was done on blood samples obtained after overnight fasting. BDI scores were also obtained in control group using BDI. Co-relation between BDI score and lipid levels was obtained in both the groups. Results: Serum lipid levels were significantly low in study group as compared to control group. There was a significant negative co-relationship between serum lipid levels with depression. Subjects of study group having lower lipid levels specifically Total Cholestrol (TC) (r = -0.78), Low-Density Lipoprotein (LDL) (r = -0.69), TG (r = -0.41) and Very Low-Density Lipoprotein (VLDL)(r = - 0.418), showed higher BDI scores (p<0.05). Conclusion: We can conclude that there is a significant relationship between low TC and depression. Similarly, low levels of serum LDL, TG and VLDL also showed significant relationship with depression. Lipid levels below a certain limit are not good as it may cause depression. Patients with low lipid levels should be screened for depression so that if necessary, corrective measures can be taken at the earliest. PMID:24596713

Kale, Anita B.; Kale, Sunil B.; Chalak, Shivaji S.; S.R., Tankhiwale; Bang, G.; Agrawal, Mohit; Kaple, Meghali

2014-01-01

409

Copyright 2003 by Lipid Research, Inc. This article is available online at http://www.jlr.org Journal of Lipid Research Volume 44, 2003 655  

E-print Network

://www.jlr.org Journal of Lipid Research Volume 44, 2003 655 Lipid rafts: bringing order to chaos Linda J. Pike1, Box 8231, St. Louis, MO 63110 Abstract Lipid rafts are subdomains of the plasma mem- brane a distinctive protein and lipid composition, all rafts do not appear to be identical in terms of either

Pike, Linda J.

410

Lipid peroxidation of i.v. lipid emulsions in TPN bags: the influence of tocopherols.  

PubMed

Four commercial i.v. lipid emulsions containing soybean oil were investigated to determine the tocopherol content. A sensitive high-performance liquid chromatography (HPLC) on a diol column was established to quantitate the tocopherol isomers in lipid emulsions. A previously described iodometric titration was used to assess the peroxide value (mmol peroxides/L). The pH was measured also. The initial tocopherol concentration ranges in three of the four commercial soybean oil-based 20% lipid emulsions studied were compared ([mg/L]: alpha: 17-23, beta: 4, gamma: 88-129, delta: 40-44). One product showed an increased alpha-tocopherol content (172 mg/L) due to supplementation during manufacture. During storage in an ethylvinyl acetate (EVA) bag at 40 degrees C under light-protection (LP) for 34 d, a lipid emulsion 20% with a natural alpha-tocopherol content showed a peroxide value (PV) of 9.18 (about 450 times the value of controls in glass bottles) with a concomittant reduction of the tocopherol isomers to 61.6% (alpha), 86.5% (gamma), and 88.9% (delta) compared to the initial values. Comparison of two lipid emulsions with different amounts of alpha-tocopherol (Lipidem 20%, B. Braun, Switzerland: 156.29 mg/L vs. Intralipid 20%, Pharmacia Upjohn, Switzerland: 8.75 mg/L) for their antioxidative capacity using the same stress conditions revealed for the emulsion with the high alpha-tocopherol content a significantly higher PV over the whole test period (after 5 wk: 33.63 vs. 6.23; P < 0.001) and an increased alpha-tocopherol decomposition (51.6% vs. 8.7%). The drop in pH was higher, also (1.9 vs. 1.0 pH units). In contrast to ordinary concentrations of about 20 mg/L, alpha-tocopherol in 20% lipid emulsions showing antioxidative properties, a supplementation with about 160 mg/L showed a prooxidative effect when exposed to ambient atmosphere in an EVA bag. PMID:9530645

Steger, P J; Mühlebach, S F

1998-02-01

411

Nucleic acid-lipid membrane interactions studied by DSC  

PubMed Central

The interactions of nucleic acids with lipid membranes are of great importance for biological mechanisms as well as for biotechnological applications in gene delivery and drug carriers. The optimization of liposomal vectors for clinical use is absolutely dependent upon the formation mechanisms, the morphology, and the molecular organization of the lipoplexes, that is, the complexes of lipid membranes with DNA. Differential scanning calorimetry (DSC) has emerged as an efficient and relatively easy-to-operate experimental technique that can straightforwardly provide data related to the thermodynamics and the kinetics of the DNA—lipid complexation and especially to the lipid organization and phase transitions within the membrane. In this review, we summarize DSC studies considering nucleic acid—membrane systems, accentuating DSC capabilities, and data analysis. Published work involving cationic, anionic, and zwitterionic lipids as well as lipid mixtures interacting with RNA and DNA of different sizes and conformations are included. It is shown that despite limitations, issues such as DNA- or RNA-induced phase separation and microdomain lipid segregation, liposomal aggregation and fusion, alterations of the lipid long-range molecular order, as well as membrane-induced structural changes of the nucleic acids can be efficiently treated by systematic high-sensitivity DSC studies. PMID:21430956

Giatrellis, Sarantis; Nounesis, George

2011-01-01

412

Original article Effect of dietary levels of lipid and carbohydrate  

E-print Network

Original article Effect of dietary levels of lipid and carbohydrate on growth performance, body of digestible carbohydrate and the highest plasma glucose level was attained later at 8°C in comparison to 18°C. trout / carbohydrate/lipid ratio / growth performance / glycaemia / temperature Résumé ― Effets

Paris-Sud XI, Université de

413

PASSAGE OF LIPID ACROSS VASCULAR ENDOTHELIUM IN NEWBORN RATS  

Microsoft Academic Search

An electron microscopic study of the fine blood vessels in the skin and muscle of 95 newborn rats (sucklings, and therefore subject to physiologic lipemia) has sho~,n that blood-borne lipid particles may leave the lumen of these vessels by two pathways, intercellular and intracellular. (a) An intercellular pathway: Some capillaries, venous capillaries and venules contain intramural, extracellular deposits of lipid

ELSI R. SUTER; GUIDO MAJNO

2010-01-01

414

POPULATION ECOLOGY Amphibian lipid levels at metamorphosis correlate  

E-print Network

In organisms that have complex life cycles, factors in the larval environment may affect both larval and adult), with limited data for one anuran species (southern leopard frog, Rana sphenocep- hala). Lipid levels were correlates Á Lipids Á Postmetamorphic survival Á Trade-offs Introduction In organisms with complex life

Georgia, University of

415

The physical chemistry of the stratum corneum lipids.  

PubMed

This article summarizes the current knowledge of the composition, self-assembly, and molecular organization of the stratum corneum (SC) lipids, reviews the evidence connecting these parameters and the barrier properties of human skin, and outlines the immediate issues in the field of SC lipid research. PMID:25230344

Boncheva, M

2014-12-01

416

Polar Lipids of Archaebacteria in Sediments and Petroleums  

Microsoft Academic Search

Glycerol tetraethers with head-to-head isoprenoid 40-carbon chains that are typical of archaebacteria, in particular of methanogens, were identified in the polar lipids of sediments and petroleums. These structures are at least partially preserved in the subsurface beyond the stage of petroleum formation. Their identification provides further evidence that a significant part of geological organic matter derives from the lipids of

B. Chappe; P. Albrecht; W. Michaelis

1982-01-01

417

Giant Unilamelar Vesicles preparation protocol -Nanion Chips Lipid stock solution  

E-print Network

Giant Unilamelar Vesicles ­ preparation protocol - Nanion Chips Lipid stock solution: · 2.5mg)(Ammonium Salt) (Avanti)) ­ only if fluorescence microscope is used. Sucrose stock solution: · 300mM Sucrose: On the electrodes system 1.5µl drops form lipid stock solution were added at 5 different places on each electrode

Movileanu, Liviu

418

Ethane Evolution: A New Index of Lipid Peroxidation  

Microsoft Academic Search

Homogenates of mouse liver and brain at 37 degrees C spontaneously formed lipid peroxides and simultaneously evolved ethane. alpha -Tocopherol, a lipid antioxidant, blocked ethane formation. When mice were injected with carbon tetrachloride (a liquid prooxidant for liver), the animals produced ethane. Ethane evolution in vivo was stimulated by prior administration of phenobarbital and it was diminished by prior injection

Caroline A. Riely; Gerald Cohen; Morris Lieberman

1974-01-01

419

Determination of the sedimentary microbial biomass by extractible lipid phosphate  

Microsoft Academic Search

The measurement of lipid phosphate is proposed as an indicator of microbial biomass in marine and estuarine sediments. This relatively simple assay can be performed on fresh, frozen or frozen-lyophilized sediment samples with chloroform methanol extraction and subsequent phosphate determination. The sedimentary lipid phosphate recovery correlates with the extractible ATP and the rate of DNA synthesis. Pulse-chase experiments show active

D. C. White; W. M. Davis; J. S. Nickels; J. D. King; R. J. Bobbie

1979-01-01

420

Algal Lipid Extraction and Upgrading to Hydrocarbons Technology Pathway  

SciTech Connect

This technology pathway case investigates the cultivation of algal biomass followed by further lipid extraction and upgrading to hydrocarbon biofuels. Technical barriers and key research needs have been assessed in order for the algal lipid extraction and upgrading pathway to be competitive with petroleum-derived gasoline-, diesel-, and jet-range hydrocarbon blendstocks.

Davis, R.; Biddy, M.; Jones, S.

2013-03-01

421

Active Lipid Management In Coronary Artery Disease (ALMICAD) Study  

Microsoft Academic Search

PurposeMany providers have implemented specialized lipid clinics to more effectively identify, monitor, and treat hyperlipidemia in patients with coronary artery disease. The effectiveness of such a strategy is not known. We sought to investigate whether a specialized clinic achieves better lipid results and clinical outcomes than standard care.

Sanjaya Khanal; Omar Obeidat; Michael P. Hudson; Mouaz Al-Mallah; Mary Bloome; Mei Lu; Adam B. Greenbaum; Aaron D. Kugelmass; W. Douglas Weaver

2007-01-01

422

Fatty Acid methyl ester profiles of bat wing surface lipids.  

PubMed

Sebocytes are specialized epithelial cells that rupture to secrete sebaceous lipids (sebum) across the mammalian integument. Sebum protects the integument from UV radiation, and maintains host microbial communities among other functions. Native glandular sebum is composed primarily of triacylglycerides (TAG) and wax esters (WE). Upon secretion (mature sebum), these lipids combine with minor cellular membrane components comprising total surface lipids. TAG and WE are further cleaved to smaller molecules through oxidation or host enzymatic digestion, resulting in a complex mixture of glycerolipids (e.g., TAG), sterols, unesterified fatty acids (FFA), WE, cholesteryl esters, and squalene comprising surface lipid. We are interested if fatty acid methyl ester (FAME) profiling of bat surface lipid could predict species specificity to the cutaneous fungal disease, white nose syndrome (WNS). We collected sebaceous secretions from 13 bat spp. using Sebutape(®) and converted them to FAME with an acid catalyzed transesterification. We found that Sebutape(®) adhesive patches removed ~6× more total lipid than Sebutape(®) indicator strips. Juvenile eastern red bats (Lasiurus borealis) had significantly higher 18:1 than adults, but 14:0, 16:1, and 20:0 were higher in adults. FAME profiles among several bat species were similar. We concluded that bat surface lipid FAME profiling does not provide a robust model predicting species susceptibility to WNS. However, these results provide baseline data that can be used for lipid roles in future ecological studies, such as life history, diet, or migration. PMID:25227993

Pannkuk, Evan L; Fuller, Nathan W; Moore, Patrick R; Gilmore, David F; Savary, Brett J; Risch, Thomas S

2014-11-01

423

Structure, Stability, and Thermodynamics of Lamellar DNA-Lipid Complexes  

E-print Network

of parallel strands of DNA intercalated in the water layers of lamellar stacks of mixed lipid bilayers, with the parallel DNA strands intercalated between. Quite different morphologies are expected to arise for otherStructure, Stability, and Thermodynamics of Lamellar DNA-Lipid Complexes Daniel Harries,* Sylvio

Harries, Daniel

424

Production of lipid compounds in the yeast Saccharomyces cerevisiae  

Microsoft Academic Search

This review describes progress using the yeast Saccharomyces cerevisiae as a model organism for the fast and efficient analysis of genes and enzyme activities involved in the lipid biosynthetic pathways of several donor organisms. Furthermore, we assess the impact of baker's yeast on the production of novel, high-value lipid compounds. Yeast can be genetically modified to produce selected substances in

M. Veen; C. Lang

2004-01-01

425

Cationic DMPC\\/DMTAP Lipid Bilayers: Molecular Dynamics Study  

Microsoft Academic Search

Cationic lipid membranes are known to form compact complexes with DNA and to be effective as gene delivery agents both in vitro and in vivo. Here we employ molecular dynamics simulations for a detailed atomistic study of lipid bilayers consisting of a mixture of cationic dimyristoyltrimethylammonium propane (DMTAP) and zwitterionic dimyristoylphosphatidylcholine (DMPC). Our main objective is to examine how the

Andrey A. Gurtovenko; Michael Patra; Mikko Karttunen; Ilpo Vattulainen

2004-01-01

426

Lipid modulation of ion channels through specific binding sites.  

PubMed

Ion channel conformational changes within the lipid membrane are a key requirement to control ion passage. Thus, it seems reasonable to assume that lipid composition should modulate ion channel function. There is increasing evidence that this implicates not just an indirect consequence of the lipid influence on the physical properties of the membrane, but also specific binding of selected lipids to certain protein domains. The result is that channel function and its consequences on excitability, contractility, intracellular signaling or any other process mediated by such channel proteins, could be subjected to modulation by membrane lipids. From this it follows that development, age, diet or diseases that alter lipid composition should also have an influence on those cellular properties. The wealth of data on the non-annular lipid binding sites in potassium channel from Streptomyces lividans (KcsA) makes this protein a good model to study the modulation of ion channel structure and function by lipids. The fact that this protein is able to assemble into clusters through the same non-annular sites, resulting in large changes in channel activity, makes these sites even more interesting as a potential target to develop lead compounds able to disrupt such interactions and hopefully, to modulate ion channel function. This Article is Part of a Special Issue Entitled: Membrane Structure and Function: Relevance in the Cell's Physiology, Pathology and Therapy. PMID:24211605

Poveda, J A; Giudici, A M; Renart, M L; Molina, M L; Montoya, E; Fernández-Carvajal, A; Fernández-Ballester, G; Encinar, J A; González-Ros, J M

2014-06-01

427

Role of Physical Structures in Bulk Oils on Lipid Oxidation  

Microsoft Academic Search

Lipid oxidation is important to food manufacturers especially when they increase unsaturated lipids in their products to improve nutritional profiles. Unfortunately, the number of antioxidants available to food manufacturers to control oxidative rancidity is limited and the approval of new antioxidants is unlikely due to economic barriers in obtaining government approval for new food additives. Therefore, new antioxidant technologies are

Wilailuk Chaiyasit; Ryan J. Elias; D. Julian McClements; Eric A. Decker

2007-01-01

428

Secondary metabolites and lipids in Chara globularis Thuill  

Microsoft Academic Search

Sterols, volatiles and lipid fatty acids were analysed in the fresh-water alga Chara globularis. Five sterols, two of them new for the genus, were identified, together with 12 fatty acids from lipids. The volatiles appeared to form a complex mixture, containing mainly acids (part of them chlorinated), terpenoids, ketones, hydrocarbons, etc. No flavonoids have been found. Antibacterial activity of extracts

Vassya Bankova; Kamen Stefanov; St. Dimitrova-Konaklieva; Gergana Keremedchieva; Xavie Frette; Christina Nikolova; Atanas Kujumgiev; Simeon Popov

2001-01-01

429

Charge-induced phase separation in lipid membranes.  

PubMed

Phase separation in lipid bilayers that include negatively charged lipids is examined experimentally. We observed phase-separated structures and determined the membrane miscibility temperatures in several binary and ternary lipid mixtures of unsaturated neutral lipid, dioleoylphosphatidylcholine (DOPC), saturated neutral lipid, dipalmitoylphosphatidylcholine (DPPC), unsaturated charged lipid, dioleoylphosphatidylglycerol (DOPG((-))), saturated charged lipid, dipalmitoylphosphatidylglycerol (DPPG((-))), and cholesterol. In binary mixtures of saturated and unsaturated charged lipids, the combination of the charged head with the saturation of the hydrocarbon tail is a dominant factor in the stability of membrane phase separation. DPPG((-)) enhances phase separation, while DOPG((-)) suppresses it. Furthermore, the addition of DPPG((-)) to a binary mixture of DPPC/cholesterol induces phase separation between DPPG((-))-rich and cholesterol-rich phases. This indicates that cholesterol localization depends strongly on the electric charge on the hydrophilic head group rather than on the ordering of the hydrocarbon tails. Finally, when DPPG((-)) was added to a neutral ternary system of DOPC/DPPC/cholesterol (a conventional model of membrane rafts), a three-phase coexistence was produced. We conclude by discussing some qualitative features of the phase behaviour in charged membranes using a free energy approach. PMID:25154325

Himeno, Hiroki; Shimokawa, Naofumi; Komura, Shigeyuki; Andelman, David; Hamada, Tsutomu; Takagi, Masahiro

2014-09-24