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1

A gas chromatographic-mass spectral assay for the quantitative determination of oleamide in biological fluids.  

PubMed

Oleamide is a putative endogenous sleep-inducing lipid which potently enhances currents mediated by GABAA and serotonin receptors. While a quantitative assay would aid in determining the role of oleamide in physiological processes, most of the available assays are lacking in sensitivity. We now describe a quantitative assay for measuring low nanogram amounts of oleamide in biological fluids using GC/MS in the selective ion-monitoring mode. The internal standard (13C18 oleamide) was added to known concentrations of oleamide, which were converted to the N-trimethylsilyl or N-tert-butyldimethylsilyl derivatives before analysis by GC/MS, yielding linear calibration curves over the range of 1-25 ng of oleamide when monitoring the m/z 338/356 fragments. Using this technique, oleamide levels were determined following solvent extraction of normal rat cerebrospinal fluid and plasma to be 44 and 9.9 ng/ml, respectively. This technique constitutes a sensitive and reliable method for determining low nanogram quantities of oleamide in biological fluids. PMID:10328778

Hanus, L O; Fales, H M; Spande, T F; Basile, A S

1999-05-15

2

Fatty acid amide hydrolase: biochemistry, pharmacology, and therapeutic possibilities for an enzyme hydrolyzing anandamide, 2-arachidonoylglycerol, palmitoylethanolamide, and oleamide 1 1 Abbreviations: AEA, anandamide, arachidonyl ethanolamide; PEA, palmitoylethanolamide, N-(2-hydroxyethyl) hexadecamide; FAAH, fatty acid amide hydrolase; CB, cannabinoid; PMSF, phenylmethylsulfonyl fluoride; MAFP, methyl arachidonyl fluorophosphonate; methAEA, arachidonyl-1?-hydroxy-2?-propylamide; and NSAIDs, nonsteroidal anti-inflammatory drugs  

Microsoft Academic Search

Fatty acid amide hydrolase (FAAH) is responsible for the hydrolysis of a number of important endogenous fatty acid amides, including the endogenous cannabimimetic agent anandamide (AEA), the sleep-inducing compound oleamide, and the putative anti-inflammatory agent palmitoylethanolamide (PEA). In recent years, there have been great advances in our understanding of the biochemical and pharmacological properties of the enzyme. In this commentary,

Christopher J Fowler; Kent-Olov Jonsson; Gunnar Tiger

2001-01-01

3

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

4

Differential proteomic analysis of the anti-depressive effects of oleamide in a rat chronic mild stress model of depression.  

PubMed

Depression is a complex psychiatric disorder, and its etiology and pathophysiology are not completely understood. Depression involves changes in many biogenic amine, neuropeptide, and oxidative systems, as well as alterations in neuroendocrine function and immune-inflammatory pathways. Oleamide is a fatty amide which exhibits pharmacological effects leading to hypnosis, sedation, and anti-anxiety effects. In the present study, the chronic mild stress (CMS) model was used to investigate the antidepressant-like activity of oleamide. Rats were exposed to 10weeks of CMS or control conditions and were then subsequently treated with 2weeks of daily oleamide (5mg/kg, i.p.), fluoxetine (10mg/kg, i.p.), or vehicle. Protein extracts from the hippocampus were then collected, and hippocampal maps were generated by way of two-dimensional gel electrophoresis (2-DE). Altered proteins induced by CMS and oleamide were identified through mass spectrometry and database searches. Compared to the control group, the CMS rats exhibited significantly less body weight gain and decreased sucrose consumption. Treatment with oleamide caused a reversal of the CMS-induced deficit in sucrose consumption. In the proteomic analysis, 12 protein spots were selected and identified. CMS increased the levels of adenylate kinase isoenzyme 1 (AK1), nucleoside diphosphate kinase B (NDKB), histidine triad nucleotide-binding protein 1 (HINT1), acyl-protein thioesterase 2 (APT-2), and glutathione S-transferase A4 (GSTA4). Compared to the CMS samples, seven spots changed significantly following treatment with oleamide, including GSTA4, glutathione S-transferase A6 (GSTA6), GTP-binding nuclear protein Ran (Ran-GTP), ATP synthase subunit d, transgelin-3, small ubiquitin-related modifier 2 (SUMO2), and eukaryotic translation initiation factor 5A-1 (eIF5A1). Of these seven proteins, the level of eIF5A1 was up-regulated, whereas the remaining proteins were down-regulated. In conclusion, oleamide has antidepressant-like properties in the CMS rat model. The identification of proteins altered by CMS and oleamide treatment provides support for targeting these proteins in the development of novel therapies for depression. PMID:25641667

Ge, Lin; Zhu, Ming-Ming; Yang, Jing-Yu; Wang, Fang; Zhang, Rong; Zhang, Jing-Hai; Shen, Jing; Tian, Hui-Fang; Wu, Chun-Fu

2015-04-01

5

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

6

Preventive Effects of a Fermented Dairy Product against Alzheimer’s Disease and Identification of a Novel Oleamide with Enhanced Microglial Phagocytosis and Anti-Inflammatory Activity  

PubMed Central

Despite the ever-increasing number of patients with dementia worldwide, fundamental therapeutic approaches to this condition have not been established. Epidemiological studies suggest that intake of fermented dairy products prevents cognitive decline in the elderly. However, the active compounds responsible for the effect remain to be elucidated. The present study aims to elucidate the preventive effects of dairy products on Alzheimer’s disease and to identify the responsible component. Here, in a mouse model of Alzheimer’s disease (5xFAD), intake of a dairy product fermented with Penicillium candidum had preventive effects on the disease by reducing the accumulation of amyloid ? (A?) and hippocampal inflammation (TNF-? and MIP-1? production), and enhancing hippocampal neurotrophic factors (BDNF and GDNF). A search for preventive substances in the fermented dairy product identified oleamide as a novel dual-active component that enhanced microglial A? phagocytosis and anti-inflammatory activity towards LPS stimulation in vitro and in vivo. During the fermentation, oleamide was synthesized from oleic acid, which is an abundant component of general dairy products owing to lipase enzymatic amidation. The present study has demonstrated the preventive effect of dairy products on Alzheimer’s disease, which was previously reported only epidemiologically. Moreover, oleamide has been identified as an active component of dairy products that is considered to reduce A? accumulation via enhanced microglial phagocytosis, and to suppress microglial inflammation after A? deposition. Because fermented dairy products such as camembert cheese are easy to ingest safely as a daily meal, their consumption might represent a preventive strategy for dementia. PMID:25760987

Ano, Yasuhisa; Ozawa, Makiko; Kutsukake, Toshiko; Sugiyama, Shinya; Uchida, Kazuyuki; Yoshida, Aruto; Nakayama, Hiroyuki

2015-01-01

7

Lipids  

NSDL National Science Digital Library

Quiz questions from the organic chemistry question bank provide students with an excellent opportunity to review key concepts. This group of questions focuses on fat soluble molecules called lipids. Questions on fatty acids, triacylglycerols, terpenes, and steroids are all provided here for review.

Reich, Ieva

8

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.

Paul Anderson

2013-03-12

9

On the Lipid Composition of Human Meibum and Tears: Comparative Analysis of Nonpolar Lipids  

PubMed Central

PURPOSE To qualitatively compare the nonpolar lipids present in meibomian gland (MG) secretions (samples T1) with aqueous tears (AT) collected from the lower tear menisci of healthy, non-dry eye volunteers using either glass microcapillaries (samples T2) or Schirmer test strips (samples T3). METHODS Samples T1 to T3 were analyzed with the use of high-pressure liquid chromatography/positive ion mode atmospheric pressure chemical ionization mass spectrometry. Where possible, the unknown lipids were compared with known standards. RESULTS Samples T1 had the simplest lipid composition among all the tested specimens. Samples T2 and T3 were similar to each other but were noticeably different from samples T1. In addition to all the compounds detected in samples T1, lower molecular weight wax esters and other compounds were found in samples T2 and T3. No appreciable amounts of fatty acid amides (e.g., oleamide), ceramides, or monoacyl glycerols were routinely detected. The occasionally observed minor signals of oleamide (m/z 282) in samples T3 were attributed to the contamination of the samples with common plasticizers routinely found in plastic ware extractives and organic solvents. CONCLUSIONS The MG is a prominent source of lipids for the tear film. However, it would have been a mistake to exclude from consideration other likely sources of lipids such as conjunctiva, cornea, and tears produced by the lacrimal glands. These data showed that lipids in AT are more complex than MG secretions, which necessitates more cautious interpretation of the functions of the latter in the tear film. PMID:18487374

Butovich, Igor A.

2009-01-01

10

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

PubMed Central

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

2002-01-01

11

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; Mölle, Matthias; Born, Jan

2013-01-01

12

Vagotomy Attenuates Brain Cytokines and Sleep Induced by Peripherally Administered Tumor Necrosis Factor-? and Lipopolysaccharide in Mice  

PubMed Central

Study Objective: Systemic tumor necrosis factor-? (TNF-?) is linked to sleep and sleep altering pathologies in humans. Evidence from animals indicates that systemic and brain TNF-? have a role in regulating sleep. In animals, TNF-? or lipopolysaccharide (LPS) enhance brain pro-inflammatory cytokine expression and sleep after central or peripheral administration. Vagotomy blocks enhanced sleep induced by systemic TNF-? and LPS in rats, suggesting that vagal afferent stimulation by TNF-? enhances pro-inflammatory cytokines in sleep-related brain areas. However, the effects of systemic TNF-? on brain cytokine expression and mouse sleep remain unknown. Design: We investigated the role of vagal afferents on brain cytokines and sleep after systemically applied TNF-? or LPS in mice. Measurements and Results: Spontaneous sleep was similar in vagotomized and sham-operated controls. Vagotomy attenuated TNF-?- and LPS-enhanced non-rapid eye movement sleep (NREMS); these effects were more evident after lower doses of these substances. Vagotomy did not affect rapid eye movement sleep responses to these substances. NREMS electroencephalogram delta power (0.5-4 Hz range) was suppressed after peripheral TNF-? or LPS injections, although vagotomy did not affect these responses. Compared to sham-operated controls, vagotomy did not affect liver cytokines. However, vagotomy attenuated interleukin-1 beta (IL-1?) and TNF-? mRNA brain levels after TNF-?, but not after LPS, compared to the sham-operated controls. Conclusions: We conclude that vagal afferents mediate peripheral TNF-?-induced brain TNF-? and IL-1? mRNA expressions to affect sleep. We also conclude that vagal afferents alter sleep induced by peripheral pro-inflammatory stimuli in mice similar to those occurring in other species. Citation: Zielinski MR; Dunbrasky DL; Taishi P; Souza G; Krueger JM. Vagotomy attenuates brain cytokines and sleep induced by peripherally administered tumor necrosis factor-? and lipopolysaccharide in mice. SLEEP 2013;36(8):1227-1238. PMID:23904683

Zielinski, Mark R.; Dunbrasky, Danielle L.; Taishi, Ping; Souza, Gianne; Krueger, James M.

2013-01-01

13

Metabolomic study of lipids in serum for biomarker discovery in Alzheimer's disease using direct infusion mass spectrometry.  

PubMed

In this study, we demonstrated the potential of direct infusion mass spectrometry for the lipidomic characterization of Alzheimer's disease. Serum samples were extracted for lipids recovery, and directly analyzed using an electrospray source. Metabolomic fingerprints were subjected to multivariate analysis in order to discriminate between groups of patients and healthy controls, and then some key-compounds were identified as possible markers of Alzheimer's disease. Major differences were found in lipids, although some low molecular weight metabolites also showed significant changes. Thus, important metabolic pathways involved in neurodegeneration could be studied on the basis of these perturbations, such as membrane breakdown (phospholipids and diacylglycerols), oxidative stress (prostaglandins, imidazole and histidine), alterations in neurotransmission systems (oleamide and putrescine) and hyperammonaemia (guanidine and arginine). Moreover, it is noteworthy that some of these potential biomarkers have not been previously described for Alzheimer's disease. PMID:24992214

González-Domínguez, R; García-Barrera, T; Gómez-Ariza, J L

2014-09-01

14

Effect of Leu-enkephalin and delta sleep inducing peptide (DSIP) on endogenous noradrenaline release by rat brain synaptosomes  

SciTech Connect

The nonapeptide delta-sleep inducing peptide (DSIP) causes specific changes in the encephalogram of recipient animals: It prolongs the phase of long-wave or delta sleep. The cellular mechanism of action of DSIP has not yet been explained. To test the hyporhesis that this peptide or its degradation product may be presynaptic regulators of catecholamine release, the action of Leu-enkephaline, DSIP, and amino acids composing DSIP on release of endogenous noradrenalin (NA) from synaptosomes during depolarization was compared. Subcellular fractions from cerebral hemisphere of noninbred male albino rats were isolated. Lactate dehydrogenase activity was determined in the suspension of synaptosomes before and after addition of 0.5% Triton X-100. The results were subjected to statistical analysis, using the Wilcoxon-Mann-Whitney nonparametric test.

Lozhanets, V.V.; Anosov, A.K.

1986-01-01

15

Degradation and aggregation of delta sleep-inducing peptide (DSIP) and two analogs in plasma and serum  

SciTech Connect

The biostability of DSIP (delta sleep-inducing peptide) and two analogs in blood was investigated in order to determine if rates of inactivation contribute to variable effects in vivo. Incubation of DSIP in human or rat blood led to release of products having retention times on a gel filtration column equivalent to Trp. Formation of products was dependent on temperature, time, and species. Incubation of /sup 125/I-N-Tyr-DSIP and /sup 125/I-N-Tyr-P-DSIP, a phosphorylated analog, revealed slower degradation and, in contrast to DSIP, produced complex formation. An excess of unlabeled material did not displace the radioactivity supporting the assumption of non-specific binding/aggregation. It was concluded that the rapid disappearance of injected DSIP in blood was due to degradation, whereas complex formation together with slower degradation resulted in longer persistence of apparently intact analogs. Whether this could explain the sometimes stronger and more consistent effects of DSIP-analogs remains to be examined.

Graf, M.V.; Saegesser, B.; Schoenenberger, G.A.

1987-07-01

16

[Delta-sleep inducing peptide entrapment and release from polymer hydrogels based on modified polyvinyl alcohol in vitro].  

PubMed

The aim of the study was to entrap delta-sleep inducing peptide (DSIP) in cross-linked poly(vinyl alcohol)-based hydrogels of different structures and to evaluate peptide release kinetics from these hydrogels using an in vitro model. Isotropic and macroporous hydrogels on the basis of poly(vinyl alcohol) acrylic derivative (Acr-PVA) as well as macroporous hydogels containing epoxy groups which were synthesized by copolymerization of this monomer with glycidyl methacrylate. The isotropic hydrogels were fabricated at positive temperatures while the macroporous hydrogels (cryogels) were prepared at the temperatures below zero. The peptide was entrapped into macroporous modified PVA hydrogels by addition of a peptide solution on previously fabricated matrices, while into PVA-GMA hydrogels containing epoxy groups peptide immobilization was carried out by incubation of hydrogel matrices in the peptide solution. In the case of isotropic hydrogels the peptide was added into the polymer mixture at a hydrogel formation reaction. The peptide release kinetics was studied by incubation of hydrogels in PBS (pH 7.4), in physiological solution (0.9% NaCl) and in water. DSIP concentration in supernatants was determined by phase-reverse HPLC. DSIP release from the macroporous PVA hydrogel after 30 min incubation was 74, 70 and 64% in water, PBS and 0.9% NaCl, relatively, and it was completed in 3 hs. From the isotropic hydrogel the release neither peptide nor products of its degradation was not observed even after 48 hs of incubation. For freshly prepared hydrogel the release kinetics was as follows: 27 and 78% in 30 and 33 hs, relatively. In the case of the lyophilized hydrogel samples the peptide release was 63% in 30 min incubation while drying patterns at room temperature for 3 days resulted in significant peptide loss because its structure damage. PMID:23650723

Sukhanova, T V; Artiukhov, A A; Prudchenko, I A; Golunova, A S; Seminikhina, M A; Shtil'man, M I; Markvicheva, E A

2013-01-01

17

Comparison of DSIP- (delta sleep-inducing peptide) and P-DSIP-like (phosphorylated) immunoreactivity in cerebrospinal fluid of patients with senile dementia of Alzheimer type, multi-infarct syndrome, communicating hydrocephalus and Parkinson's disease  

Microsoft Academic Search

The concentrations of delta sleep-inducing peptide (DSIP)-like (DSIP-LI) and P-DSIP-like (phosphorylated, Ser7) immunoreactivity (P-DSIP-LI) were measured by specific radioimmunoassay in the cerebrospinal fluid (CSF) of patients with senile dementia of the Alzheimer type [SDAT, subdivided into early (S1), middle (S2) and late dementia (S3)], multi-infarct dementia (MD), Parkinson's disease (PD), vascular disease (VD) and communicating hydrocephalus (H), as well as

Andreas Ernst; Hinrich Cramer; Denise Strubel; Francis Kuntzmann; Guido A. Schoenenberger

1987-01-01

18

Milk lipids  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

19

Lipid Nanotechnology  

PubMed Central

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

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

2013-01-01

20

Lipid14: The Amber Lipid Force Field  

PubMed Central

The AMBER lipid force field has been updated to create Lipid14, allowing tensionless simulation of a number of lipid types with the AMBER MD package. The modular nature of this force field allows numerous combinations of head and tail groups to create different lipid types, enabling the easy insertion of new lipid species. The Lennard-Jones and torsion parameters of both the head and tail groups have been revised and updated partial charges calculated. The force field has been validated by simulating bilayers of six different lipid types for a total of 0.5 ?s each without applying a surface tension; with favorable comparison to experiment for properties such as area per lipid, volume per lipid, bilayer thickness, NMR order parameters, scattering data, and lipid lateral diffusion. As the derivation of this force field is consistent with the AMBER development philosophy, Lipid14 is compatible with the AMBER protein, nucleic acid, carbohydrate, and small molecule force fields. PMID:24803855

2015-01-01

21

Lipid antigens in immunity  

PubMed Central

Lipids are not only a central part of human metabolism but also play diverse and critical roles in the immune system. As such, they can act as ligands of lipid-activated nuclear receptors, control inflammatory signaling through bioactive lipids such as prostaglandins, leukotrienes, lipoxins, resolvins, and protectins, and modulate immunity as intracellular phospholipid- or sphingolipid-derived signaling mediators. In addition, lipids can serve as antigens and regulate immunity through the activation of lipid-reactive T cells, which is the topic of this review. We will provide an overview of the mechanisms of lipid antigen presentation, the biology of lipid-reactive T cells, and their contribution to immunity. PMID:23999493

Dowds, C. Marie; Kornell, Sabin-Christin

2014-01-01

22

Dizocilpine and cycloheximide prevent inhibition of c-Fos gene expression by delta sleep-inducing peptide in the paraventricular nucleus of the hypothalamus in rats with different resistance to emotional stress.  

PubMed

The effects of the non-competitive NMDA-receptor blocker MK-801 (dizocilpine) and the protein synthesis inhibitor cycloheximide on the delta sleep-inducing peptide (DSIP) inhibition of c-Fos immediate early gene expression were studied in the parvocellular subdivision of the hypothalamic paraventricular nucleus (pPVN) of male Wistar rats with either high or low resistance to emotional stress, predicted from differences in their open-field behaviour. The experiments show that intraperitoneal (i.p.) DSIP injection (60 nmol/kg) decreased the number of Fos-immunoreactive (Fos-IR) cells in the pPVN, activated by immobilization. The NMDA-receptor antagonist dizocilpine (MK-801) (90 nmol i.c.v.) prevented the inhibition of c-Fos expression by DSIP in the pPVN of rats predisposed to emotional stress. The protein synthesis inhibitor cycloheximide (210 nmol i.c.v.) prevented the inhibition of c-Fos expression by DSIP in the pPVN of rats that were resistant to emotional stress. The experiments indicate that the DSIP effect on c-Fos gene expression might be mediated by NMDA-receptors. DSIP may induce production of some protein transcription factors, transmitting a signal from membrane NMDA-receptors to the nucleus. PMID:22094385

Umriukhin, P E; Koplik, E V; Sudakov, K V

2012-01-11

23

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

24

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

25

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

26

Perspectives on marine zooplankton lipids  

Microsoft Academic Search

We developed new perspectives to identify important questions and to propose approaches for future research on marine food web lipids. They were related to (i) structure and function of lipids, (ii) lipid changes during critical life phases, (iii) trophic marker lipids, and (iv) potential impact of climate change. The first addresses the role of lipids in membranes, storage lipids, and

G. Kattner; R. F. Lee; R. Campbell; D. Deibel; S. Falk-Petersen; M. Graeve; B. W. Hansen; H. J. Hirche; S. H. Jónasdóttir; M. L. Madsen; P. Mayzaud; D. Müller-Navarra; P. D. Nichols; G.-A. Paffenhöfer; D. Pond; H. Saito; D. Stübing; P. Virtue

2007-01-01

27

Lipids in the Limelight  

NSDL National Science Digital Library

The term lipid can bring to mind many associations. Unfortunately, these are often negative, such as the contribution that excessive dietary fat makes to heart disease. But lipids are also essential components of cell membranes, and during the past several years, cell biologists have found that lipid molecules play many more dynamic roles as well, helping to control a majority of cellular activities. Consequently, lipids are major determinants of many pathologies in addition to heart disease. This article introduces a special issue of Science highlighting a few of the recent emerging themes in lipid biology.

Lisa Chong (AAAS; )

2001-11-30

28

Phospholipids and lipid droplets.  

PubMed

Lipid droplets are ubiquitous cellular organelles that allow cells to store large amounts of neutral lipids for membrane synthesis and energy supply in times of starvation. Compared to other cellular organelles, lipid droplets are structurally unique as they are made of a hydrophobic core of neutral lipids and are separated to the cytosol only by a surrounding phospholipid monolayer. This phospholipid monolayer consists of over a hundred different phospholipid molecular species of which phosphatidylcholine is the most abundant lipid class. However, lipid droplets lack some indispensable activities of the phosphatidylcholine biogenic pathways suggesting that they partially depend on other organelles for phosphatidylcholine synthesis. Here, we discuss very recent data on the composition, origin, transport and function of the phospholipid monolayer with a particular emphasis on the phosphatidylcholine metabolism on and for lipid droplets. In addition, we highlight two very important quantitative aspects: (i) The amount of phospholipid required for lipid droplet monolayer expansion is remarkably small and (ii) to maintain the invariably round shape of lipid droplets, a cell must have a highly sensitive but so far unknown mechanism that regulates the ratio of phospholipid to neutral lipid in lipid droplets. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism. PMID:23246574

Penno, Anke; Hackenbroich, Gregor; Thiele, Christoph

2013-03-01

29

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

30

Microalgae lipid characterization.  

PubMed

To meet the growing interest of utilizing microalgae biomass in the production of biofuels and nutraceutical and pharmaceutical lipids, we need suitable analytical methods and a comprehensive database for their lipid components. The objective of the present work was to demonstrate methodology and provide data on fatty acid composition, lipid class content and composition, characteristics of the unsaponifiables, and type of chlorophylls of five microalgae. Microalgae lipids were fractionated into TAG, FFA, and polar lipids using TLC, and the composition of fatty acids in total lipids and in each lipid class, hydrocarbons, and sterols were determined by GC-MS. Glyco- and phospholipids were profiled by LC/ESI-MS. Chlorophylls and their related metabolites were qualified by LC/APCI-MS. The melting and crystallization profiles of microalgae total lipids and their esters were analyzed by DSC to evaluate their potential biofuel applications. Significant differences and complexities of lipid composition among the algae tested were observed. The compositional information is valuable for strain selection, downstream biomass fractionation, and utilization. PMID:25608629

Yao, Linxing; Gerde, Jose A; Lee, Show-Ling; Wang, Tong; Harrata, Kamel A

2015-02-18

31

Lipids of Ankistrodesmus braunii  

Microsoft Academic Search

Ankistrodesmus braunii was grown to stationary phase on a chemically defined medium and its cellular lipids were analyzed. The lipid content was found to vary from 18 to 73 percent of dry weight for cultures of different age and method of analysis. The pigments of the nonsaponifiable fraction were separated by adsorption chromatography and counter-current extraction and tentatively identified. The

Virginia R. Williams; Rosamond McMillan

1961-01-01

32

Lysosomal Lipid Storage Diseases  

PubMed Central

Lysosomal lipid storage diseases, or lipidoses, are inherited metabolic disorders in which typically lipids accumulate in cells and tissues. Complex lipids, such as glycosphingolipids, are constitutively degraded within the endolysosomal system by soluble hydrolytic enzymes with the help of lipid binding proteins in a sequential manner. Because of a functionally impaired hydrolase or auxiliary protein, their lipid substrates cannot be degraded, accumulate in the lysosome, and slowly spread to other intracellular membranes. In Niemann-Pick type C disease, cholesterol transport is impaired and unesterified cholesterol accumulates in the late endosome. In most lysosomal lipid storage diseases, the accumulation of one or few lipids leads to the coprecipitation of other hydrophobic substances in the endolysosomal system, such as lipids and proteins, causing a “traffic jam.” This can impair lysosomal function, such as delivery of nutrients through the endolysosomal system, leading to a state of cellular starvation. Therapeutic approaches are currently restricted to mild forms of diseases with significant residual catabolic activities and without brain involvement. PMID:21502308

Schulze, Heike; Sandhoff, Konrad

2011-01-01

33

Lipids: Absorption and transport  

Technology Transfer Automated Retrieval System (TEKTRAN)

Lipid has long been recognized as an important dietary component. Dietary lipid (fat) is a critical source of metabolic energy and a substrate for the synthesis of metabolically active compounds (essential fatty acids), and serves as a carrier for other nutrients such as the fat-soluble vitamins A, ...

34

Idiopathic bilateral lipid keratopathy.  

PubMed Central

A 52-year-old Mexican man presented with asymptomatic, bilaterally symmetrical lipid infiltrates of the cornea and adjacent limbus. No evidence of previous ocular disease or systemic disorder of lipid metabolism could be detected. Penetrating keratoplasty of the right eye was required. The cornea was rigid and thick, with posterior bulging into the anterior chamber. Light microscopy revealed deep corneal lipid granules, foamy histiocytes, vascularisation, and chronic non-granulomatous inflammation. Transmission electron microscopy showed extracellular lipid spaces and numerous intracytoplasmic lipid vacuoles in histiocytes, keratocytes, conjunctival epithelium, and the endothelium of blood vessels in the corneal stroma and adjacent limbal conjunctiva. Histochemical analysis revealed the presence of neutral fats, free fatty acids, cholesterol, and phospholipids. Images PMID:3395592

Alfonso, E.; Arrellanes, L.; Boruchoff, S. A.; Ormerod, L. D.; Albert, D. M.

1988-01-01

35

Lipids of Archaeal Viruses  

PubMed Central

Archaeal viruses represent one of the least known territory of the viral universe and even less is known about their lipids. Based on the current knowledge, however, it seems that, as in other viruses, archaeal viral lipids are mostly incorporated into membranes that reside either as outer envelopes or membranes inside an icosahedral capsid. Mechanisms for the membrane acquisition seem to be similar to those of viruses infecting other host organisms. There are indications that also some proteins of archaeal viruses are lipid modified. Further studies on the characterization of lipids in archaeal viruses as well as on their role in virion assembly and infectivity require not only highly purified viral material but also, for example, constant evaluation of the adaptability of emerging technologies for their analysis. Biological membranes contain proteins and membranes of archaeal viruses are not an exception. Archaeal viruses as relatively simple systems can be used as excellent tools for studying the lipid protein interactions in archaeal membranes. PMID:23049284

Roine, Elina; Bamford, Dennis H.

2012-01-01

36

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

37

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

38

Lipid oxidation in food emulsions  

Microsoft Academic Search

Lipid oxidation is a major cause of quality deterioration in food emulsions. The design of foods with improved quality depends on a better understanding of the physicochemical mechanisms of lipid oxidation in these systems. The oxidation of emulsified lipids differs from that of bulk lipids, because of the presence of the droplet membrane, the interactions between the ingredients, and the

John N. Coupland; D. Julian McClements

1996-01-01

39

Cytarabine Lipid Complex Injection  

MedlinePLUS

Cytarabine lipid complex is used to treat lymphomatous meningitis (a type of cancer in the covering of ... to take.tell your doctor if you have meningitis. Your doctor will probably not want you to ...

40

Metabolism. Part III: Lipids.  

ERIC Educational Resources Information Center

Describes the metabolic processes of complex lipids, including saponification, activation and transport, and the beta-oxidation spiral. Discusses fatty acid degradation in regard to biochemical energy and ketone bodies. (TW)

Bodner, George M.

1986-01-01

41

Lipid-Mediated Endocytosis  

PubMed Central

Receptor-mediated endocytosis is used by a number of viruses and toxins to gain entry into cells. Some have evolved to use specific lipids in the plasma membrane as their receptors. They include bacterial toxins such as Shiga and Cholera toxin and viruses such as mouse polyoma virus and simian virus 40. Through multivalent binding to glycosphingolipids, they induce lipid clustering and changes in membrane properties. Internalization occurs by unusual endocytic mechanisms involving lipid rafts, induction of membrane curvature, trans-bilayer coupling, and activation of signaling pathways. Once delivered to early endosomes, they follow diverse intracellular routes to the lumen of the ER, from which they penetrate into the cytosol. The role of the lipid receptors is central in these well-studied processes. PMID:21576253

Ewers, Helge; Helenius, Ari

2011-01-01

42

PHYSIOLOGY: Unfolding Lipid Metabolism  

NSDL National Science Digital Library

Access to the article is free, however registration and sign-in are required: A transcription factor exhibits dual roles, regulating genes that respond to improperly folded proteins and genes that control lipid synthesis.

Jay D. Horton (University of Texas Southwestern Medical Center at Dallas; Departments of Molecular Genetics and Internal Medicine)

2008-06-13

43

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

44

Lipids in human milk  

Microsoft Academic Search

I have reviewed recent (March 1995–December 1997) papers on human milk lipids including many on fatty acid (FA) composition.\\u000a The effects of maternal diets on the profiles are apparent. However, more data on the composition of milk lipids are needed.\\u000a It is noteworthy that so few papers on milk FA composition have reported analyses using high-resolution gas-liquid chromatography\\u000a columns. Two

Robert G. Jensen

1999-01-01

45

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, 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

46

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, Sébastien; Bird, David; DeBono, Allan; Durrett, Timothy P.; Franke, Rochus B.; Graham, Ian A.; Katayama, Kenta; Kelly, Amélie A.; Larson, Tony; Markham, Jonathan E.; Miquel, Martine; Molina, Isabel; Nishida, Ikuo; Rowland, Owen; Samuels, Lacey; Schmid, Katherine M.; Wada, Hajime; Welti, Ruth; Xu, Changcheng; Zallot, Rémi; Ohlrogge, John

2010-01-01

47

Lipid membranes for membrane proteins.  

PubMed

The molecular dynamics (MD) simulation of membrane proteins requires the setup of an accurate representation of lipid bilayers. This chapter describes the setup of a lipid bilayer system from scratch using generally available tools, starting with a definition of the lipid molecule POPE, generation of a lipid bilayer, energy minimization, MD simulation, and data analysis. The data analysis includes the calculation of area and volume per lipid, deuterium order parameters, self-diffusion constant, and the electron density profile. PMID:25330959

Kukol, Andreas

2015-01-01

48

Lipids and lipid binding proteins: A perfect match.  

PubMed

Lipids serve a great variety of functions, ranging from structural components of biological membranes to signaling molecules affecting various cellular functions. Several of these functions are related to the unique physico-chemical properties shared by all lipid species, i.e., their hydrophobicity. The latter, however, is accompanied by a poor solubility in an aqueous environment and thus a severe limitation in the transport of lipids in aqueous compartments such as blood plasma and the cellular soluble cytoplasm. Specific proteins which can reversibly and non-covalently associate with lipids, designated as lipid binding proteins or lipid chaperones, greatly enhance the aqueous solubility of lipids and facilitate their transport between tissues and within tissue cells. Importantly, transport of lipids across biological membranes also is facilitated by specific (membrane-associated) lipid binding proteins. Together, these lipid binding proteins determine the bio-availability of their ligands, and thereby markedly influence the subsequent processing, utilization, or signaling effect of lipids. The bio-availability of specific lipid species thus is governed by the presence of specific lipid binding proteins, the affinity of these proteins for distinct lipid species, and the presence of competing ligands (including pharmaceutical compounds). Recent studies suggest that post-translational modifications of lipid binding proteins may have great impact on lipid-protein interactions. As a result, several levels of regulation exist that together determine the bio-availability of lipid species. This short review discusses the significance of lipid binding proteins and their potential application as targets for therapeutic intervention. PMID:25154384

Glatz, Jan F C

2015-02-01

49

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

50

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

51

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

52

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

53

How proteins move lipids and lipids move proteins  

Microsoft Academic Search

Cells determine the bilayer characteristics of different membranes by tightly controlling their lipid composition. Local changes in the physical properties of bilayers, in turn, allow membrane deformation, and facilitate vesicle budding and fusion. Moreover, specific lipids at specific locations recruit cytosolic proteins involved in structural functions or signal transduction. We describe here how the distribution of lipids is directed by

Hein Sprong; Peter van der Sluijs; Gerrit van Meer

2001-01-01

54

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

55

Lipid profile in consecutive pregnancies  

Microsoft Academic Search

AIM: To describe the lipid profile of women prior to, during and after pregnancy and to assess the effect of consecutive pregnancies on the plasma lipid profile. METHODS: Blood lipid levels of 1752 women aged 20-45 years who delivered between 1999 and 2005 were measured. The lipid profile included total cholesterol, LDL-C (Low density lipoprotein), HDL-C (High density lipoprotein-C), VLDL-C

David Mankuta; Matan Elami-Suzin; Asher Elhayani; Shlomo Vinker

2010-01-01

56

The Lipid World  

NASA Astrophysics Data System (ADS)

The continuity of abiotically formed bilayer membranes with similar structures in contemporary cellular life, and the requirement for microenvironments in which large and small molecules could be compartmentalized, support the idea that amphiphilic boundary structures contributed to the emergence of life. As an extension of this notion, we propose here a `Lipid World' scenario as an early evolutionary step in the emergence of cellular life on Earth. This concept combines the potential chemical activities of lipids and other amphiphiles, with their capacity to undergo spontaneous self-organization into supramolecular structures such as micelles and bilayers. In particular, the documented chemical rate enhancements within lipid assemblies suggest that energy-dependent synthetic reactions could lead to the growth and increased abundance of certain amphiphilic assemblies. We further propose that selective processes might act on such assemblies, as suggested by our computer simulations of mutual catalysis among amphiphiles. As demonstrated also by other researchers, such mutual catalysis within random molecular assemblies could have led to a primordial homeostatic system displaying rudimentary life-like properties. Taken together, these concepts provide a theoretical framework, and suggest experimental tests for a Lipid World model for the origin of life.

Segré, Daniel; Ben-Eli, Dafna; Deamer, David W.; Lancet, Doron

2001-02-01

57

The lipid world.  

PubMed

The continuity of abiotically formed bilayer membranes with similar structures in contemporary cellular life, and the requirement for microenvironments in which large and small molecules could be compartmentalized, support the idea that amphiphilic boundary structures contributed to the emergence of life. As an extension of this notion, we propose here a 'Lipid World' scenario as an early evolutionary step in the emergence of cellular life on Earth. This concept combines the potential chemical activities of lipids and other amphiphiles, with their capacity to undergo spontaneous self-organization into supramolecular structures such as micelles and bilayers. In particular, the documented chemical rate enhancements within lipid assemblies suggest that energy-dependent synthetic reactions could lead to the growth and increased abundance of certain amphiphilic assemblies. We further propose that selective processes might act on such assemblies, as suggested by our computer simulations of mutual catalysis among amphiphiles. As demonstrated also by other researchers, such mutual catalysis within random molecular assemblies could have led to a primordial homeostatic system displaying rudimentary life-like properties. Taken together, these concepts provide a theoretical framework, and suggest experimental tests for a Lipid World model for the origin of life. PMID:11296516

Segré, D; Ben-Eli, D; Deamer, D W; Lancet, D

2001-01-01

58

Lipid multilayer gratings  

NASA Astrophysics Data System (ADS)

The interaction of electromagnetic waves with matter can be controlled by structuring the matter on the scale of the wavelength of light, and various photonic components have been made by structuring materials using top-down or bottom-up approaches. Dip-pen nanolithography is a scanning-probe-based fabrication technique that can be used to deposit materials on surfaces with high resolution and, when carried out in parallel, with high throughput. Here, we show that lyotropic optical diffraction gratings-composed of biofunctional lipid multilayers with controllable heights between ~5 and 100 nm-can be fabricated by lipid dip-pen nanolithography. Multiple materials can be simultaneously written into arbitrary patterns on pre-structured surfaces to generate complex structures and devices, allowing nanostructures to be interfaced by combinations of top-down and bottom-up fabrication methods. We also show that fluid and biocompatible lipid multilayer gratings allow label-free and specific detection of lipid-protein interactions in solution. This biosensing capability takes advantage of the adhesion properties of the phospholipid superstructures and the changes in the size and shape of the grating elements that take place in response to analyte binding.

Lenhert, Steven; Brinkmann, Falko; Laue, Thomas; Walheim, Stefan; Vannahme, Christoph; Klinkhammer, Soenke; Xu, Miao; Sekula, Sylwia; Mappes, Timo; Schimmel, Thomas; Fuchs, Harald

2010-04-01

59

The Lipid World  

Microsoft Academic Search

The continuity of abiotically formed bilayer membraneswith similar structures in contemporary cellular life,and the requirement for microenvironments in whichlarge and small molecules could be compartmentalized, support the idea that amphiphilic boundary structurescontributed to the emergence of life. As an extensionof this notion, we propose here a `Lipid World'scenario as an early evolutionary step in theemergence of cellular life on Earth.

Daniel Segré; Dafna Ben-Eli; David W. Deamer; Doron Lancet

2001-01-01

60

The Lipid World  

Microsoft Academic Search

The continuity of abiotically formed bilayer membranes with similar structures in contemporary cellular life, and the requirement for microenvironments in which large and small molecules could be compartmentalized, support the idea that amphiphilic boundary structures contributed to the emergence of life. As an extension of this notion, we propose here a `Lipid World' scenario as an early evolutionary step in

Daniel Segré; Dafna Ben-Eli; David W. Deamer; Doron Lancet

2001-01-01

61

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

62

Lipids, fatty acids, and more  

Technology Transfer Automated Retrieval System (TEKTRAN)

Energy is the most expensive component in livestock diets. Lipids are concentrated energy sources and are known to affect growth, feed efficiency, feed dust, and diet palatability. A large majority of research evaluating lipids in livestock has utilized lipids of high quality, dealt mainly with anim...

63

Functional tethered lipid bilayers.  

PubMed

Our strategy to provide the structural basis for the build-up of functional tethered membranes focuses on three approaches: the first one is based on the pre-organization of a monomolecular layer of a lipopolymer at the water/air interface which is then transferred to a solid support. Prior to deposition, the substrate is coated with a layer of benzophenone-derivatized silane molecules that allow for a stable covalent attachment by photo-cross-linking of some of the monomer units of the lipopolymer to the support. An alternative concept realizes a layer-by-layer deposition of the various structural elements: (1) the attachment layer with the reactive sites for the chemical stabilization; (2) a polymer 'cushion' prepared by adsorption and simultaneous or subsequent partial covalent binding to the reactive sites; and (3) a lipid monolayer transferred from the water/air interface, that contains a certain amount of lipids with reactive headgroups which, upon binding to the polymer tether, act as anchor lipids stabilizing the whole monolayer/cushion-composite. And finally, we build peptide-supported monolayers by first (self-) assembling amino acid sequences of various lengths via a SH-group near their N-terminus onto Au substances and use then their COO(-)-terminus to chemically attach phosphatidyl-ethanolamine lipids to form a stable monolayer of lipid-peptide conjugates. All the individual preparation steps and the various resulting (multi-) layers are characterized by surface plasmon spectroscopy, X-ray and neutron-reflectometry, contact angle measurements, IR spectroscopy, fluorescence microscopy, scanning probe microscopies, as well as, electrochemical techniques. For all tethering systems, the final membranes' architecture is obtained by fusing lipid vesicles onto the lipid monolayer. Proteins can be incorporated by either fusing vesicles that are loaded with the respective receptors, pores, or ion pumps via a reconstitution procedure, or via a transfer directly from a micellar solution to the pre-formed lipid bilayer at the solid support by a dialysis step. Two structural/dynamical features of tethered membranes which are considered to be of particular functional relevance, i.e. the degree of water uptake and, hence, the degree of swelling of the polymer support, as well as the lateral mobility of the lipid molecules in the membrane, are tested by surface plasmon optics and by measurements of the fluorescence recovery after photobleaching (FRAP), respectively. The results confirm that the presented preparation protocols yield fluid bilayers that mimic certain relevant properties of biological membranes. The functional characterization of tethered membranes, which is briefly summarized, is based on various electrochemical techniques, in particular, impedance spectroscopy, cyclic voltammetry, and chronoamperometric studies. The results obtained for reconstituted H(+)-ATPase from chloroplasts and E. coli and for cytochrome oxidase (with and without cytochrome c) confirm the incorporation of the proteins in an active form, thus, opening opportunities for novel sensor formats or offering a completely new model membrane system. PMID:11143794

Knoll, W; Frank, C W; Heibel, C; Naumann, R; Offenhäusser, A; Rühe, J; Schmidt, E K; Shen, W W; Sinner, A

2000-09-01

64

Mannosylerythritol lipids: a review  

Microsoft Academic Search

Mannosylerythritol lipids (MELs) are surface active compounds that belong to the glycolipid class of biosurfactants (BSs).\\u000a MELs are produced by Pseudozyma sp. as a major component while Ustilago sp. produces them as a minor component. Although MELs have been known for over five decades, they recently regained attention\\u000a due to their environmental compatibility, mild production conditions, structural diversity, self-assembling properties

Joseph Irudayaraj Arutchelvi; Sumit Bhaduri; Parasu Veera Uppara; Mukesh Doble

2008-01-01

65

Tear Film Lipids  

PubMed Central

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.

2013-01-01

66

Painted supported lipid membranes  

PubMed Central

We report herein measurements on a novel type of supported lipid films, which we call painted supported membranes (PSM). These membranes are formed in a self-assembly process on alkylated gold films from an organic solution. The formation process was investigated with surface plasmon resonance microscopy. The optical and electrical properties of the films were determined for various types of lipids and as a function of temperature by means of cyclic voltammetry and potential relaxation after charge injection. We could show that these films exhibit an extraordinarily high specific resistivity which, depending on the lipid, may be as high as 109 ohm/cm2. We could also show that due to this low conductivity, an electrical polarization across the PSM relaxes with characteristic time constants of up to 20 min. The electrical properties together with their high mechanical stability and accessibility to surface sensitive techniques make these films well suitable model membranes for optical and electrical investigations. Examples for such applications are given in the subsequent article by Seifert et al. ImagesFIGURE 3FIGURE 4 PMID:19431873

Florin, E.-L.; Gaub, H. E.

1993-01-01

67

Intestinal lipid absorption and transport.  

PubMed

The purpose of this review is to update the reader on our current knowledge of the digestion, uptake, and transport of dietary lipid. In particular, it discusses how intestinal lipid transporters may play a role in the uptake of lipids by the enterocytes, and how chylomicrons are formed in the enterocytes and packaged for export into the lymphatic system through exocytosis. The classification and properties of lipids is first described followed by a discussion of structured lipids and their role in human nutrition. Digestion of triacylglycerols takes place in the stomach aided by the enzyme gastric lipase. The origin and properties of lingual and gastric lipase are reviewed. Most digestion of triacylglycerols by pancreatic lipase occurs in the intestinal lumen. Similarly, digestion of cholesteryl ester and phospholipids also takes place in the intestinal lumen. This review describes in considerable detail the uptake of lipid digestion products by the enterocytes, particularly the role of recently identified lipid transporters. The intracellular trafficking and the resynthesis of complex lipids from the lipid digestion products are talked about, particularly within the context of the recently generated knockout mouse that lacks the key lipid reesterification enzymes. Finally, the mechanisms of the formation and secretion of chylomicrons is described and clinical disorders discussed. PMID:11229876

Phan, C T; Tso, P

2001-03-01

68

Lipid Simulations: A Perspective on Lipids in Action  

PubMed Central

In this article, we provide an overview of lipid simulations, describing how a computer can be used as a laboratory for lipid research. We briefly discuss the methodology of lipid simulations followed by a number of topical applications that show the benefit of computer modeling for complementing experiments. In particular, we show examples of cases in which simulations have made predictions of novel phenomena that have later been confirmed by experimental studies. Overall, the applications discussed in this article focus on the most recent state of the art and aim to provide a perspective of where the field of lipid simulations stands at the moment. PMID:21441592

Vattulainen, Ilpo; Rog, Tomasz

2011-01-01

69

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

70

Lipid classification, structures and tools?  

PubMed Central

The study of lipids has developed into a research field of increasing importance as their multiple biological roles in cell biology, physiology and pathology are becoming better understood. The Lipid Metabolites and Pathways Strategy (LIPID MAPS) consortium is actively involved in an integrated approach for the detection, quantitation and pathway reconstruction of lipids and related genes and proteins at a systems-biology level. A key component of this approach is a bioinformatics infrastructure involving a clearly defined classification of lipids, a state-of-the-art database system for molecular species and experimental data and a suite of user-friendly tools to assist lipidomics researchers. Herein, we discuss a number of recent developments by the LIPID MAPS bioinformatics core in pursuit of these objectives. This article is part of a Special Issue entitled Lipodomics and Imaging Mass Spectrometry. PMID:21704189

Fahy, Eoin; Cotter, Dawn; Sud, Manish; Subramaniam, Shankar

2012-01-01

71

RF Microalgal lipid content characterization  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

72

Lipid composition of marmoset saliva.  

PubMed

The lipid content and composition of marmoset saliva was investigated. Extraction of the dialyzed and lyophilized saliva with chloroform/methanol yielded 15.6 +/- 3.1 mg of lipids/100 ml of saliva. Of the total lipids, 41.7% were represented by neutral lipids, 50.7% by glycolipids and 7.6% by phospholipids. Neutral lipids had a high content of free fatty acids (67.0%), cholesterol and its esters (20.0%) and triglycerides (11.8%). The glycolipid fraction was comprised of simple glycosphingolipids (13.2%), and of neutral and sulfated glyceroglucolipids (86.8%), whereas sphingomyelin, phosphatidylcholine and phosphatidylethanolamine accounted for 63.6% of the total phospholipids. The results indicate that marmoset saliva, in comparison to that of human, contains twice as much of total lipids and exhibits an elevated level of phospholipids, and glycolipids. PMID:6148183

Murty, V L; Slomiany, B L; Zdebska, E; Slomiany, A; Mandel, I D; Levy, M

1984-01-01

73

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

74

Multiple bonds for the lipid interest.  

PubMed

Polyene lipids and alkyne lipids allow study of lipid organization, dynamics and metabolism. Both types of lipids contain multiple bonds as the essential functional group, leading to minimal disturbance of the hydrophobic properties on which the characteristic behavior of lipids is based. Polyene lipids can directly be traced due to their intrinsic fluorescence, while alkyne lipids need the copper-catalyzed click reaction to an azido-reporter for detection. This review describes recent developments in synthesis and application of both types of lipid analogs with emphasis on metabolic tracing and microscopy imaging. This article is part of a Special Issue entitled Tools to study lipid functions. PMID:24412758

Kuerschner, Lars; Thiele, Christoph

2014-08-01

75

Hormones regulating lipid metabolism and plasma lipids in childhood obesity  

Microsoft Academic Search

OBJECTIVE: To review the mechanisms by which leptin, insulin and adiponectin influence lipid metabolism and plasma lipids in obesity, as well as to describe the associations between these hormones in prepubertal children.METHOD:Revision of relevant papers published in the last 5 y related to the interactions of leptin, insulin and adiponectin, with special emphasis on those reporting potential mechanisms by which

M Gil-Campos; R Cañete; A Gil

2004-01-01

76

INOSITOL LIPID REGULATION OF LIPID TRANSFER IN SPECIALIZED MEMBRANE DOMAINS  

PubMed Central

SUMMARY The highly dynamic membranous network of eukaryotic cells allows spatial organization of biochemical reactions to suit the complex metabolic needs of the cell. The unique lipid composition of organelle membranes in the face of dynamic membrane activities assumes that lipid gradients are constantly generated and maintained. Important advances have been made in identifying specialized membrane compartments and lipid transfer mechanisms that are critical for generating and maintaining lipid gradients. Remarkably, one class of minor phospholipids -- the phosphoinositides -- is emerging as important regulators of these processes. Here, we summarize several lines of research that led to our current understanding of the connection between phosphoinositides and the transport of structural lipids and offer some thoughts on general principles possibly governing these processes. PMID:23489878

Kim, Yeun Ju; Hernandez, Maria-Luisa Guzman; Balla, Tamas

2013-01-01

77

Lipid-lowering agents.  

PubMed

The role of lipid lowering in reducing the risk of mortality and morbidity from cardiovascular disease (CVD) is well established. Treatment particularly aimed at decreasing low-density lipoprotein cholesterol (LDL-C) is effective in reducing the risk of death from coronary heart disease and stroke. Statins form the cornerstone of treatment. However, in some individuals with a high risk of CVD who are unable to achieve their target LDL-C due to either intolerance or lack of efficacy, there is the need for alternative therapies. This review provides an overview of the different classes of currently available lipid-lowering medications including statins, fibrates, bile acid sequestrants (resins), and omega-3 fatty acids. Data are presented on their indications, pharmacology, and the relevant end point clinical trial data with these drugs. It also discusses the human trial data on some novel therapeutic agents that are being developed including those for homozygous familial hypercholesterolemia--the antisense oligonucleotide mipomersen and the microsomal transfer protein inhibitor lomitapide. Data are presented on phase II and III trials on agents with potentially wider applications, cholesterol ester transfer protein inhibitors and proprotein convertase subtilisin kexin 9 inhibitors. The data on a licensed gene therapy for lipoprotein lipase deficiency are also presented. PMID:23811423

Ewang-Emukowhate, Mfon; Wierzbicki, Anthony S

2013-09-01

78

Diabetic Retinopathy and Serum Lipids  

Microsoft Academic Search

The association between serum lipid levels and diabetic retinopathy has been investigated in many studies. Some studies show a positive relationship between serum cholesterol and low-density lipoprotein levels and retinal hard exudation. Other studies show serum triglyceride levels as being important in the progression of retinopathy. Certain other studies show no relationship between serum lipid levels and diabetic retinopathy. We

K T Yeo

79

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

80

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 ...

81

Crystallizing Membrane Proteins in Lipidic Mesophases. A Host Lipid Screen  

SciTech Connect

The default lipid for the bulk of the crystallogenesis studies performed to date using the cubic mesophase method is monoolein. There is no good reason, however, why this 18-carbon, cis-monounsaturated monoacylglycerol should be the preferred lipid for all target membrane proteins. The latter come from an array of biomembrane types with varying properties that include hydrophobic thickness, intrinsic curvature, lateral pressure profile, lipid and protein makeup, and compositional asymmetry. Thus, it seems reasonable that screening for crystallizability based on the identity of the lipid creating the hosting mesophase would be worthwhile. For this, monoacylglycerols with differing acyl chain characteristics, such as length and olefinic bond position, must be available. A lipid synthesis and purification program is in place in the author's laboratory to serve this need. In the current study with the outer membrane sugar transporter, OprB, we demonstrate the utility of host lipid screening as a means for generating diffraction-quality crystals. Host lipid screening is likely to prove a generally useful strategy for mesophase-based crystallization of membrane proteins.

Li, Dianfan; Lee, Jean; Caffrey, Martin (Trinity); (Limerick)

2011-11-30

82

Lipid mediators in diabetic nephropathy  

PubMed Central

The implications of lipid lowering drugs in the treatment of diabetic nephropathy have been considered. At the same time, the clinical efficacy of lipid lowering drugs has resulted in improvement in the cardiovascular functions of chronic kidney disease (CKD) patients with or without diabetes, but no remarkable improvement has been observed in the kidney outcome. Earlier lipid mediators have been shown to cause accumulative effects in diabetic nephropathy (DN). Here, we attempt to analyze the involvement of lipid mediators in DN. The hyperglycemia-induced overproduction of diacyglycerol (DAG) is one of the causes for the activation of protein kinase C (PKCs), which is responsible for the activation of pathways, including the production of VEGF, TGF?1, PAI-1, NADPH oxidases, and NF?B signaling, accelerating the development of DN. Additionally, current studies on the role of ceramide are one of the major fields of study in DN. Researchers have reported excessive ceramide formation in the pathobiological conditions of DN. There is less report on the effect of lipid lowering drugs on the reduction of PKC activation and ceramide synthesis. Regulating PKC activation and ceramide biosynthesis could be a protective measure in the therapeutic potential of DN. Lipid lowering drugs also upregulate anti-fibrotic microRNAs, which could hint at the effects of lipid lowering drugs in DN. PMID:25206927

2014-01-01

83

Volumetric stability of lipid bilayers.  

PubMed

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 10 °C and 50 °C. 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 20 °C. 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; Nagle, John F

2012-11-28

84

Lipid biology of breast cancer  

PubMed Central

Alterations in lipid metabolism have been reported in many types of cancer. Lipids have been implicated in the regulation of proliferation, differentiation, apoptosis, inflammation, autophagy, motility and membrane homeostasis. It is required that their biosynthesis is tightly regulated to ensure homeostasis and to prevent unnecessary energy expenditure. This review focuses on the emerging understanding of the role of lipids and lipogenic pathway regulation in breast cancer, including parallels drawn from the study of metabolic disease models, and suggestions on how these findings can potentially be exploited to promote gains in HER2/neu-positive breast cancer research. PMID:23562840

Baumann, Jan; Sevinsky, Christopher; Conklin, Douglas S.

2014-01-01

85

Serum lipid levels in Sjogren's syndrome  

Microsoft Academic Search

Objectives. Altered lipid levels may occur in autoimmune diseases, for example low cholesterol levels have been described in rheumatoid arthritis (RA). Serum lipid profiles in patients with Sjogren's syndrome (SS) have not been investigated. We hypothesized decreased lipid levels in SS patients and an inverse relationship with disease activity. Methods. Serum lipid levels [total cholesterol, high-density lipoprotein (HDL), low-density lipoprotein

B. M. Lodde; V. Sankar; M. R. Kok; R. A. Leakan; P. P. Tak; S. R. Pillemer

2006-01-01

86

Serum lipid levels in Sjogren's syndrome  

Microsoft Academic Search

Objectives. Altered lipid levels may occur in autoimmune diseases, for example low cholesterol levels have been described in rheumatoid arthritis (RA). Serum lipid profiles in patients with Sjogren's syndrome (SS) have not been investigated. We hypothesized decreased lipid levels in SS patients and an inverse relationship with disease activity. Methods. Serum lipid levels (total cholesterol, high-density lipoprotein (HDL), low-density lipoprotein

B. M. Lodde; V. Sankar; M. R. Kok; R. A. Leakan; P. P. Tak; S. R. Pillemer

2005-01-01

87

Autoxidation of Unsaturated Lipids in Food Emulsion  

Microsoft Academic Search

Unsaturated lipids having various physiological roles are of significance in biochemistry, nutrition, medicine, and food. However, the susceptibility of lipids to oxidation is a major cause of quality deterioration in food emulsions. The reaction mechanism and factors that influence oxidation are appreciably different for emulsified lipids and bulk lipids. This article gives a brief overview of the current knowledge on

Yue-E Sun; Wei-Dong Wang; Hong-Wei Chen; Chao Li

2011-01-01

88

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

89

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

E-print Network

Lipid digestion and effects of diets rich in lipids on carbohydrate and nitrogen digestion-Genès-Champanelle, France This review deals with ruminal metabolism and intestinal digestion of lipids, and with the conse- quences of lipid supplementation on carbohy- drate and nitrogen digestion. Ruminal hydrolysis of lipids

Boyer, Edmond

90

[Biochemical analysis of epidermal lipids].  

PubMed

According to the knowledge acquired some 15 years ago, the cutaneous lipids may be classified into 2 families: the "neutral" lipids, represented by cholesterol, cholesterol esters, cholesterol sulphate, triglycerides, free fatty acids, squalen and alcanes, and the "polar" lipids including phospholipids (phosphatidylcholine, phosphatidylserine, phosphatidylethanolamine, sphingomyeline) and sphingolipids (ceramides I-VII, monohexosylceramides). From the functional point of view, free fatty acids, cholesterol, and ceramides organised in layers are the most important components of intercellular spaces of the stratum corneum. Analytic methods have been recently developed to help understand the structural organisation of these various molecules within the horny layer and their influence on the epidermal barrier function. Raman microspectroscopy or X-ray diffraction are most frequently used. Differential calorimetry and fluorescence or infrared spectroscopy provide complementary information. The principal findings are: lamellar structure depends on the presence of ceramides supplemented by adequate quantities of free fatty acids and cholesterol; ceramide chains interact to provide the ordered structure and ceramide-1 is necessary for stabilisation of lipid layers; cholesterol may regulate the molecular mobility of hydrocarbon chains within the bi-layers. Knowledge of the molecular structure of the barrier lipids finds several applications, e.g.: in pharmacology--conception of new formulations adapted for percutaneous and topical application of drugs; in dermatology--comprehension of physiopathologic mechanisms of various dermatoses; in biotechnology--development of skin substitutes with valid stratum corneum barrier; in cosmetics--choice of best formulations suited for reconstruction of the intercellular lipid substance. PMID:14567192

Martini, M C

2003-07-01

91

Lipid bilayers on nano-templates  

DOEpatents

A lipid bilayer on a nano-template comprising a nanotube or nanowire and a lipid bilayer around the nanotube or nanowire. One embodiment provides a method of fabricating a lipid bilayer on a nano-template comprising the steps of providing a nanotube or nanowire and forming a lipid bilayer around the polymer cushion. One embodiment provides a protein pore in the lipid bilayer. In one embodiment the protein pore is sensitive to specific agents

Noy, Aleksandr (Belmont, CA); Artyukhin, Alexander B. (Menlo Park, CA); Bakajin, Olgica (San Leandro, CA); Stoeve, Pieter (Davis, CA)

2009-08-04

92

Lipid interactions during virus entry and infection  

PubMed Central

Summary For entry and infection viruses have developed numerous strategies to subjugate indispensable cellular factors and functions. Host cell lipids and cellular lipid synthesis machinery are no exception. Not only do viruses exploit existing lipid signalling and modifications for virus entry and trafficking, they also reprogram lipid synthesis, metabolism, and compartmentalization for assembly and egress. Here we review these various concepts and highlight recent progress in understanding viral interactions with host cell lipids during entry and assembly. PMID:25131438

Mazzon, Michela; Mercer, Jason

2014-01-01

93

Nanoparticle-lipid bilayer interactions studied with lipid bilayer arrays.  

PubMed

The widespread environmental presence and commercial use of nanoparticles have raised significant health concerns as a result of many in vitro and in vivo assays indicating toxicity of a wide range of nanoparticle species. Many of these assays have identified the ability of nanoparticles to damage cell membranes. These interactions can be studied in detail using artificial lipid bilayers, which can provide insight into the nature of the particle-membrane interaction through variation of membrane and solution properties not possible with cell-based assays. However, the scope of these studies can be limited because of the low throughput characteristic of lipid bilayer platforms. We have recently described an easy to use, parallel lipid bilayer platform which we have used to electrically investigate the activity of 60 nm diameter amine and carboxyl modified polystyrene nanoparticles (NH2-NP and COOH-NP) with over 1000 lipid bilayers while varying lipid composition, bilayer charge, ionic strength, pH, voltage, serum, particle concentration, and particle charge. Our results confirm recent studies finding activity of NH2-NP but not COOH-NP. Detailed analysis shows that NH2-NP formed pores 0.3-2.3 nm in radius, dependent on bilayer and solution composition. These interactions appear to be electrostatic, as they are regulated by NH2-NP surface charge, solution ionic strength, and bilayer charge. The ability to rapidly measure a large number of nanoparticle and membrane parameters indicates strong potential of this bilayer array platform for additional nanoparticle bilayer studies. PMID:25853986

Lu, Bin; Smith, Tyler; Schmidt, Jacob J

2015-04-24

94

Lipid Metabolism, Apoptosis and Cancer Therapy  

PubMed Central

Lipid metabolism is regulated by multiple signaling pathways, and generates a variety of bioactive lipid molecules. These bioactive lipid molecules known as signaling molecules, such as fatty acid, eicosanoids, diacylglycerol, phosphatidic acid, lysophophatidic acid, ceramide, sphingosine, sphingosine-1-phosphate, phosphatidylinositol-3 phosphate, and cholesterol, are involved in the activation or regulation of different signaling pathways. Lipid metabolism participates in the regulation of many cellular processes such as cell growth, proliferation, differentiation, survival, apoptosis, inflammation, motility, membrane homeostasis, chemotherapy response, and drug resistance. Bioactive lipid molecules promote apoptosis via the intrinsic pathway by modulating mitochondrial membrane permeability and activating different enzymes including caspases. In this review, we discuss recent data in the fields of lipid metabolism, lipid-mediated apoptosis, and cancer therapy. In conclusion, understanding the underlying molecular mechanism of lipid metabolism and the function of different lipid molecules could provide the basis for cancer cell death rationale, discover novel and potential targets, and develop new anticancer drugs for cancer therapy. PMID:25561239

Huang, Chunfa; Freter, Carl

2015-01-01

95

Mass Spectrometry Methodology in Lipid Analysis  

PubMed Central

Lipidomics is an emerging field, where the structures, functions and dynamic changes of lipids in cells, tissues or body fluids are investigated. Due to the vital roles of lipids in human physiological and pathological processes, lipidomics is attracting more and more attentions. However, because of the diversity and complexity of lipids, lipid analysis is still full of challenges. The recent development of methods for lipid extraction and analysis and the combination with bioinformatics technology greatly push forward the study of lipidomics. Among them, mass spectrometry (MS) is the most important technology for lipid analysis. In this review, the methodology based on MS for lipid analysis was introduced. It is believed that along with the rapid development of MS and its further applications to lipid analysis, more functional lipids will be identified as biomarkers and therapeutic targets and for the study of the mechanisms of disease. PMID:24921707

Li, Lin; Han, Juanjuan; Wang, Zhenpeng; Liu, Jian’an; Wei, Jinchao; Xiong, Shaoxiang; Zhao, Zhenwen

2014-01-01

96

Lipid metabolism in prostate cancer  

PubMed Central

The malignant transformation of cells requires adaptations across multiple metabolic processes to satisfy the energy required for their increased rate of proliferation. Dysregulation of lipid metabolism has been a hallmark of the malignant phenotype; increased lipid accumulation secondary to changes in the levels of a variety of lipid metabolic enzymes has been documented in a variety of tumors, including prostate. Alterations in prostate lipid metabolism include upregulation of several lipogenic enzymes as well as of enzymes that function to oxidize fatty acids as an energy source. Cholesterol metabolism and phospholipid metabolism are also affected. With respect to lipogenesis, most studies have concentrated on increased expression and activity ofthe de novo fatty acid synthesis enzyme, fatty acid synthase (FASN), with suggestions that FASN might function as an oncogene. A central role for fatty acid oxidation in supplying energy to the prostate cancer cell is supported by the observation that the peroxisomal enzyme, ?-methylacyl-CoA racemase (AMACR), which facilitates the transformation of branched chain fatty acids to a form suitable for ?-oxidation, is highly overexpressed in prostate cancer compared with normal prostate. Exploitation of the alterations in lipid metabolic pathways in prostate cancer could result in the development of new therapeutic modalities as well as provide candidates for new prognostic and predictive biomarkers. AMACR has already proven to be a valuable biomarker in distinguishing normal from malignant prostate tissue, and is used routinely in clinical practice. PMID:25374912

Wu, Xinyu; Daniels, Garrett; Lee, Peng; Monaco, Marie E

2014-01-01

97

It’s a lipid’s world: Bioactive lipid metabolism and signaling in neural stem cell differentiation  

PubMed Central

Lipids are often considered membrane components whose function is to embed proteins into cell membranes. In the last two decades, studies on brain lipids have unequivocally demonstrated that many lipids have critical cell signaling functions; they are called “bioactive lipids”. Pioneering work in Dr. Robert Ledeen’s laboratory has shown that two bioactive brain sphingolipids, sphingomyelin and the ganglioside GM1 are major signaling lipids in the nuclear envelope. In addition to derivatives of the sphingolipid ceramide, the bioactive lipids discussed here belong to the classes of terpenoids and steroids, eicosanoids, and lysophospholipids. These lipids act mainly through two mechanisms: 1) direct interaction between the bioactive lipid and a specific protein binding partner such as a lipid receptor, protein kinase or phosphatase, ion exchanger, or other cell signaling protein; and 2) formation of lipid microdomains or rafts that regulate the activity of a group of raft-associated cell signaling proteins. In recent years, a third mechanism has emerged, which invokes lipid second messengers as a regulator for the energy and redox balance of differentiating neural stem cells (NSCs). Interestingly, developmental niches such as the stem cell niche for adult NSC differentiation may also be metabolic compartments that respond to a distinct combination of bioactive lipids. The biological function of these lipids as regulators of NSC differentiation will be reviewed and their application in stem cell therapy discussed. PMID:22246226

Bieberich, Erhard

2012-01-01

98

Chemical and structural investigation of lipid nanoparticles: drug-lipid interaction and molecular distribution  

NASA Astrophysics Data System (ADS)

Lipid nanoparticles are a promising alternative to existing carriers in chemical or drug delivery systems. A key challenge is to determine how chemicals are incorporated and distributed inside nanoparticles, which assists in controlling chemical retention and release characteristics. This study reports the chemical and structural investigation of ?-oryzanol loading inside a model lipid nanoparticle drug delivery system composed of cetyl palmitate as solid lipid and Miglyol 812® as liquid lipid. The lipid nanoparticles were prepared by high pressure homogenization at varying liquid lipid content, in comparison with the ?-oryzanol free systems. The size of the lipid nanoparticles, as measured by the photon correlation spectroscopy, was found to decrease with increased liquid lipid content from 200 to 160 nm. High-resolution proton nuclear magnetic resonance (1H-NMR) measurements of the medium chain triglyceride of the liquid lipid has confirmed successful incorporation of the liquid lipid in the lipid nanoparticles. Differential scanning calorimetric and powder x-ray diffraction measurements provide complementary results to the 1H-NMR, whereby the crystallinity of the lipid nanoparticles diminishes with an increase in the liquid lipid content. For the distribution of ?-oryzanol inside the lipid nanoparticles, the 1H-NMR revealed that the chemical shifts of the liquid lipid in ?-oryzanol loaded systems were found at rather higher field than those in ?-oryzanol free systems, suggesting incorporation of ?-oryzanol in the liquid lipid. In addition, the phase-separated structure was observed by atomic force microscopy for lipid nanoparticles with 0% liquid lipid, but not for lipid nanoparticles with 5 and 10% liquid lipid. Raman spectroscopic and mapping measurements further revealed preferential incorporation of ?-oryzanol in the liquid part rather than the solid part of in the lipid nanoparticles. Simple models representing the distribution of ?-oryzanol and lipids (solid and liquid) inside the lipid nanoparticle systems are proposed.

Anantachaisilp, Suranan; Meejoo Smith, Siwaporn; Treetong, Alongkot; Pratontep, Sirapat; Puttipipatkhachorn, Satit; Rungsardthong Ruktanonchai, Uracha

2010-03-01

99

Lipid emulsions in parenteral nutrition.  

PubMed

Lipid emulsions containing a physical mixture of medium and long chain triglycerides (MCT/LCT) are a well-proven concept in parenteral nutrition of critically ill patients. Having a demonstrably higher utilization rate, MCT/LCT emulsions do not impair liver function, produce less immune and no reticuloendothelial system function compromise, and do not interfere with pulmonary hemodynamics or gas exchange. A reduced content of n-6 polyunsaturated fatty acids can also be obtained by using newer preparations based on structured triglycerides or olive oil. Further studies are necessary in order to investigate these new lipid emulsions versus the physical mixture of MCT/LCT. A promising substrate in the development of lipid emulsions can be seen in fish oils. With regard to current literature, fish oils have a beneficial influence on the pathophysiological response to endotoxins and exert important modulations on eicosanoid and cytokine biology. Furthermore their intravenous use may improve organ perfusion in different critical situations. PMID:10364625

Adolph, M

1999-01-01

100

Pulmonary Arterial-Venous Differences in Lipids and Lipid Metabolites  

Microsoft Academic Search

This study was designed to reevaluate the effectiveness of the lungs in taking up lipids from the blood, and to establish whether or not the blood triglycerides so extracted are metabolized. 8 normal human males were studied. With the subject fasting and supine, a percutaneous catheter was placed in the pulmonary artery, another in the superior vena cava, and a

Christian W. Zauner; Göran Fex; Sven-Eric Lindell

1985-01-01

101

Triglyceride Blisters in Lipid Bilayers: Implications for Lipid Droplet Biogenesis and the Mobile Lipid Signal in Cancer Cell Membranes  

Microsoft Academic Search

Triglycerides have a limited solubility, around 3%, in phosphatidylcholine lipid bilayers. Using millisecond-scale course grained molecular dynamics simulations, we show that the model lipid bilayer can accommodate a higher concentration of triolein (TO) than earlier anticipated, by sequestering triolein molecules to the bilayer center in the form of a disordered, isotropic, mobile neutral lipid aggregate, at least 17 nm in

Himanshu Khandelia; Lars Duelund; Kirsi I. Pakkanen; John H. Ipsen; Darren R. Flower

2010-01-01

102

The Membrane and Lipids as Integral Participants in Signal Transduction: Lipid Signal Transduction for the Non-Lipid Biochemist  

ERIC Educational Resources Information Center

Reviews of signal transduction have often focused on the cascades of protein kinases and protein phosphatases and their cytoplasmic substrates that become activated in response to extracellular signals. Lipids, lipid kinases, and lipid phosphatases have not received the same amount of attention as proteins in studies of signal transduction.…

Eyster, Kathleen M.

2007-01-01

103

NUTRIGENETICS, PLASMA LIPIDS AND CARDIOVASCULAR RISK  

Technology Transfer Automated Retrieval System (TEKTRAN)

Cardiovascular diseases (CVD) result from complex interactions between genetic and environmental factors. The evidence supports that gene-environment interactions modulate plasma lipid concentrations and potentially CVD risk. The findings from studies examining gene-diet interactions and lipid metab...

104

Lipid diffusion in alcoholic environment.  

PubMed

We have studied the effects of a high concentration of butanol and octanol on the phase behavior and on the lateral mobility of 1,2-palmitoyl-sn-glycero-3-phosphocholine (DPPC) by means of differential scanning calorimetry and pulsed-gradient stimulated-echo (PGSTE) NMR spectroscopy. A lowering of the lipid transition from the gel to the liquid-crystalline state for the membrane-alcohol systems has been observed. NMR measurements reveal three distinct diffusions in the DPPC-alcohol systems, characterized by a high, intermediate, and slow diffusivity, ascribed to the water, the alcohol, and the lipid, respectively. The lipid diffusion process is promoted in the liquid phase while it is hindered in the interdigitated phase due to the presence of alcohols. Furthermore, in the interdigitated phase, lipid lateral diffusion coefficients show a slight temperature dependence. To the best of our knowledge, this is the first time that lateral diffusion coefficients on alcohol with so a long chain, and at low temperatures, are reported. By the Arrhenius plots of the temperature dependence of the diffusion coefficients, we have evaluated the apparent activation energy in both the liquid and in the interdigitated phase. The presence of alcohol increases this value in both phases. An explanation in terms of a free volume model that takes into account also for energy factors is proposed. PMID:25036819

Rifici, Simona; Corsaro, Carmelo; Crupi, Cristina; Nibali, Valeria Conti; Branca, Caterina; D'Angelo, Giovanna; Wanderlingh, Ulderico

2014-08-01

105

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

106

Resveratrol in Solid Lipid Nanoparticles  

Microsoft Academic Search

This report investigates the possibility of producing solid lipid nanoparticles as protective vehicle of resveratrol, an antioxidant characterised by a fast trans-cis isomerisation. SLN aqueous dispersions were produced by hot melt homogenisation technique and characterised. It was found that the presence of tetradecyl-?-cyclodextrin in SLN formulation induced an improvement of nanoparticle characteristics. Moreover a significant reduction in resveratrol photodegradation was

Maria Eugenia Carlotti; Simona Sapino; Elena Ugazio; Marina Gallarate; Silvia Morel

2011-01-01

107

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

108

Restoration of stratum corneum with nacre lipids  

Microsoft Academic Search

To discover potential new products for the atopic dermatitis treatment, lipids extracted from nacre from the oyster Pinctada margaritifera were tested on artificially dehydrated skin explants. Expression of filaggrin and transglutaminase 1 was investigated after treatment of dehydrated skin with P. margaritifera lipid extracts according to light microscopy after labelling with specific monoclonal antibodies. The lipids were extracted from the

Marthe Rousseau; Laurent Bédouet; Elian Lati; Philippe Gasser; Karine Le Ny; Evelyne Lopez

2006-01-01

109

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

110

Physiological aspects of human milk lipids  

Microsoft Academic Search

Human milk from healthy and well-nourished mothers is the preferred form of feeding for all healthy newborn infants. The nutrient supply with human milk supports normal growth and development of the infant. Here the general characteristics of human milk lipids and recent knowledge on lactational physiology, composition and functional aspects of human milk lipids are discussed. Lipids in human milk

Berthold Koletzko; Maria Rodriguez-Palmero; Hans Demmelmair; Nataša Fidler; Robert Jensen; Thorsten Sauerwald

2001-01-01

111

Lipid raft microdomains and neurotransmitter signalling  

Microsoft Academic Search

Lipid rafts are specialized structures on the plasma membrane that have an altered lipid composition as well as links to the cytoskeleton. It has been proposed that these structures are membrane domains in which neurotransmitter signalling might occur through a clustering of receptors and components of receptor-activated signalling cascades. The localization of these proteins in lipid rafts, which is affected

John A. Allen; Robyn A. Halverson-Tamboli; Mark M. Rasenick

2006-01-01

112

Transformation of lipids in activated sludge  

Microsoft Academic Search

Transformation of lipids in activated sludge treatment plants is of interest for two reasons: lipids contribute 30-40% of the chemical oxygen demand (COD) in wastewater, and they may stimulate the growth of filamentous microorganisms in nutrient removal activated sludge plants. The transformation of lipids was investigated under aerobic and anoxic conditions by measuring the oxygen and nitrate uptake rates (OUR

T. E. Dueholm; K. H. Andreasen; P. H. Nielsen

2001-01-01

113

Tilt modulus of a lipid monolayer  

Microsoft Academic Search

In addition to the familiar bending and stretching deformations, lipid monolayers and bilayers in their disordered state are often subjected to tilt deformations, occurring for instance in structural rearrangements accompanying membrane fusion, or upon insertion of “oblique” hydrophobic proteins into lipid bilayers. We study the elastic response of a flat lipid monolayer to a tilt deformation, using the spatial and

S. May; Y. Kozlovsky; A. Ben-Shaul; M. M. Kozlov

2004-01-01

114

Spontaneous Formation of Lipid Nanotubes and Lipid Nanofibers from Giant Charged Dendrimer Lipids  

NASA Astrophysics Data System (ADS)

Liposomes have attracted much scientific interest due to their applications in model cells studies and in drug encapsulation. We report on the discovery of new vesicle phases formed in mixtures of MVLBG2, DOPC and water. MVLBG2 is a newly synthesized highly charged (16+) lipid (K. Ewert et al., JACS, 2006) with giant dendrimer headgroup thus leading to a high spontaneous curvature of the molecule. In combination with zero-curvature DOPC, MVLBG2 exhibits a rich phase diagram showing novel vesicle morphologies such as bones, lipid nanotubes and nanofibers as revealed by differential contrast microscopy (DIC) and cryo-TEM. At the micron scale DIC reveals a new phase consisting of bone-like vesicles. This novel morphology persists down to the nanometer scale as shown by cryo-TEM. The nanotubes are of diameter 10-50 nm, length > 1?m and consist of a single lipid bilayer. A surprising new morphology arises resulting from a spontaneous topological transition from tubes to lipid nanorods. Funded by DOE DE-FG-02-06ER46314, NIH GM-59288, NSF DMR-0503347.

Zidovska, Alexandra; Ewert, Kai K.; Safinya, Cyrus R.; Quispe, Joel; Carragher, Bridgett; Potter, Clinton S.

2007-03-01

115

Emerging targets in lipid-based therapy?  

PubMed Central

The use of prostaglandins and NSAIDS in the clinic has proven that lipid mediators and their associated pathways make attractive therapeutic targets. When contemplating therapies involving lipid pathways, several basic agents come to mind. There are the enzymes and accessory proteins that lead to the metabolism of lipid substrates, provided through diet or through actions of lipases, the subsequent lipid products, and finally the lipid sensors or receptors. There is abundant evidence that molecules along this lipid continuum can serve as prognostic and diagnostic indicators and are in fact viable therapeutic targets. Furthermore, lipids themselves can be used as therapeutics. Despite this, the vernacular dialog pertaining to “biomarkers” does not routinely include mention of lipids, though this is rapidly changing. Collectively these agents are becoming more appreciated for their respective roles in diverse disease processes from cancer to preterm labor and are receiving their due appreciation after decades of ground work in the lipid field. By relating examples of disease processes that result from dysfunction along the lipid continuum, as well as examples of lipid therapies and emerging technologies, this review is meant to inspire further reading and discovery. PMID:23261527

Tucker, Stephanie C.; Honn, Kenneth V.

2013-01-01

116

Lipid metabolism in Drosophila: development and disease.  

PubMed

Proteins, nucleic acids, and lipids are three major components of the cell. Despite a few basic metabolic pathways, we know very little about lipids, compared with the explosion of knowledge about proteins and nucleic acids. How many different forms of lipids are there? What are the in vivo functions of individual lipid? How does lipid metabolism contribute to normal development and human health? Many of these questions remain unanswered. For over a century, the fruit fly Drosophila melanogaster has been used as a model organism to study basic biological questions. In recent years, increasing evidences proved that Drosophila models are highly valuable for lipid metabolism and energy homeostasis researches. Some recent progresses of lipid metabolic regulation during Drosophila development and in Drosophila models of human diseases will be discussed in this review. PMID:23257293

Liu, Zhonghua; Huang, Xun

2013-01-01

117

Correlation between lipid plane curvature and lipid chain order.  

PubMed Central

The 1-palmitoyl-2-oleoyl-phosphatidylethanolamine: 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPE:POPC) system has been investigated by measuring, in the inverted hexagonal (HII) phase, the intercylinder spacings (using x-ray diffraction) and orientational order of the acyl chains (using 2H nuclear magnetic resonance). The presence of 20 wt% dodecane leads to the formation of a HII phase for the composition range from 0 to 39 mol% of POPC in POPE, as ascertained by x-ray diffraction and 2H nuclear magnetic resonance. The addition of the alkane induces a small decrease in chain order, consistent with less stretched chains. An increase in temperature or in POPE proportion leads to a reduction in the intercylinder spacing, primarily due to a decrease in the water core radius. A temperature increase also leads to a reduction in the orientational order of the lipid acyl chains, whereas the POPE proportion has little effect on chain order. A correlation is proposed to relate the radius of curvature of the cylinders in the inverted hexagonal phase to the chain order of the lipids adopting the HII phase. A simple geometrical model is proposed, taking into account the area occupied by the polar headgroup at the interface and the orientational order of the acyl chains reflecting the contribution of the apolar core. From these parameters, intercylinder spacings are calculated that agree well with the values determined experimentally by x-ray diffraction, for the variations of both temperature and POPE:POPC proportion. This model suggests that temperature increases the curvature of lipid layers, mainly by increasing the area subtended by the hydrophobic core through chain conformation disorder, whereas POPC content affects primarily the headgroup interface contribution. The frustration of lipid layer curvature is also shown to be reflected in the acyl chain order measured in the L alpha phase, in the absence of dodecane; for a given temperature, increased order is observed when the curling tendencies of the lipid plane are more pronounced. PMID:8744312

Lafleur, M; Bloom, M; Eikenberry, E F; Gruner, S M; Han, Y; Cullis, P R

1996-01-01

118

Targeting Protein Lipidation in Disease  

PubMed Central

Fatty acids and/or isoprenoids are covalently attached to a variety of disease-related proteins. The distinct chemical properties of each of these hydrophobic moieties allow lipid modification to serve as a mechanism to regulate protein structure, localization and function. This review highlights recent progress in identifying inhibitors of protein lipidation and their effects on human disease. Myristoylation inhibitors have shown promise in blocking the action of human pathogens. Although inhibitors that block prenylation of Ras proteins have not yet been successful for cancer treatment, they may be efficacious in the rare premature aging syndrome progeria. Agents that alter the palmitoylation status of Ras, Wnt and Hh proteins have recently been discovered, and represent the next generation of potential chemotherapeutics. PMID:22342806

Resh, Marilyn D.

2012-01-01

119

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

120

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

121

Specificity of Intramembrane Protein–Lipid Interactions  

PubMed Central

Our concept of biological membranes has markedly changed, from the fluid mosaic model to the current model that lipids and proteins have the ability to separate into microdomains, differing in their protein and lipid compositions. Since the breakthrough in crystallizing membrane proteins, the most powerful method to define lipid-binding sites on proteins has been X-ray and electron crystallography. More recently, chemical biology approaches have been developed to analyze protein–lipid interactions. Such methods have the advantage of providing highly specific cellular probes. With the advent of novel tools to study functions of individual lipid species in membranes together with structural analysis and simulations at the atomistic resolution, a growing number of specific protein–lipid complexes are defined and their functions explored. In the present article, we discuss the various modes of intramembrane protein–lipid interactions in cellular membranes, including examples for both annular and nonannular bound lipids. Furthermore, we will discuss possible functional roles of such specific protein–lipid interactions as well as roles of lipids as chaperones in protein folding and transport. PMID:21536707

Contreras, Francesc-Xabier; Ernst, Andreas Max; Wieland, Felix; Brügger, Britta

2011-01-01

122

Some Pharmacological Effects of Delta-Sleep-Inducing Peptide (DSIP)  

Microsoft Academic Search

The synthetic nonapeptide DSIP was studied in rabbits and cats under normal conditions and under conditions of disturbed sleep. In other experiments, the effect of the oligopeptide on withdrawal jumping provoked by naloxone in morphine-dependent mice was studied. In rabbits, DSIP at 25 ?g·kg–1 i.v. and 1 mg·kg–1 s.c. augmented spindle-dominated, light nonREM sleep and prevented hyposomnia after a stressful

R. Scherschlicht; L. Aeppli; P. Polc; W. Haefely

1984-01-01

123

Lipid Disturbances in Psoriasis: An Update  

PubMed Central

Psoriasis is a common disease with the population prevalence ranging from 2% to 3%. Its prevalence in the population is affected by genetic, environmental, viral, infectious, immunological, biochemical, endocrinological, and psychological factors, as well as alcohol and drug abuse. In the recent years, psoriasis has been recognised as a systemic disease associated with numerous multiorgan abnormalities and complications. Dyslipidemia is one of comorbidities in psoriatic patients. Lipid metabolism studies in psoriasis have been started at the beginning of the 20th century and are concentrated on skin surface lipids, stratum corneum lipids and epidermal phospholipids, serum lipids, dermal low-density lipoproteins in the psoriatic skin, lipid metabolism, oxidative stress and correlations between inflammatory parameters, lipid parameters and clinical symptoms of the disease. On the basis of the literature data, psoriasis can be described as an immunometabolic disease. PMID:20706605

Pietrzak, Aldona; Michalak-Stoma, Anna; Chodorowska, Gra?yna; Szepietowski, Jacek C.

2010-01-01

124

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

125

Plasma lipid concentrations during episodic occupational stress  

Microsoft Academic Search

The possibility that stress affects plasma lipid concentrations has been the subject of recent investigation, but the findings\\u000a are equivocal in nonlaboratory settings. To determine whether psychological stress contributes to variability in plasma lipid\\u000a concentrations and concomitant changes in health behaviors, the effect of increased work load on plasma lipids and apolipoproteins\\u000a was examined in 173 lawyers. Plasma cholesterol, triglyceride,

Barbara S. McCann; G. Andrew H. Benjamin; Charles W. Wilkinson; Barbara M. Retzlaff; Joan Russo; Robert H. Knopp

1999-01-01

126

Lipids to the Top of Hair Biology  

PubMed Central

Little attention has been given to the impact of lipid metabolism on hair follicle biology and pathology. Three recent papers (one in the current issue) describe a major effect of altered lipid metabolism on hair growth. A direct link was made to at least one form of cicatricial alopecia, but the role lipids play in other follicular pathologies, such as the acneiform conditions, are inadequately explored and must be tested. PMID:20393475

Stenn, Kurt S.; Karnik, Pratima

2010-01-01

127

Identification and composition of turnip root lipids  

Microsoft Academic Search

Two varieties of turnip, Laurentian and Wye, were examined for their lipid and fatty acid composition. Lipids extracted with\\u000a 80% ethanol contained variable quantities of phosphatidic acid, which was considered to be an artifact. Crude lipids were\\u000a fractionated by TLC, and fatty acids and sterols were analyzed by GLC. Among the common phospholipids, cardiolipid and phosphatidyl\\u000a glycerol were abundant components.

Marius Lepage

1967-01-01

128

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

129

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

130

Lipid sac area as a proxy for individual lipid content of arctic calanoid copepods  

PubMed Central

We present an accurate, fast, simple and non-destructive photographic method to estimate wax ester and lipid content in single individuals of the calanoid copepod genus Calanus and test this method against gas-chromatographic lipid measurements. PMID:20824043

Vogedes, Daniel; Varpe, Øystein; Søreide, Janne E.; Graeve, Martin; Berge, Jørgen; Falk-Petersen, Stig

2010-01-01

131

Impact of lipid content and composition on lipid oxidation and protein carbonylation in experimental fermented sausages.  

PubMed

This study aims to investigate the effect of lipid content (?4%, ?10% and ?15%) and composition (different lipid sources; animal fat and sunflower oil) on the oxidative stability of proteins and lipids in experimental fermented sausages. Increasing the lipid content of sausages enhanced the susceptibility of lipids to oxidation whereas the effect on the formation of specific carbonyls from protein oxidation was not so evident. Sausages manufactured with different lipid sources affected the susceptibility of lipids and proteins to oxidation as a likely result of the modifications in the fatty acid profile, as well as to the presence of antioxidant compounds. While the fatty acid profile had a major effect on the occurrence and extent of lipid oxidation, the presence of compounds with potential antioxidant activity may be more influential on the extent of protein carbonylation. PMID:24206687

Fuentes, Verónica; Estévez, Mario; Ventanas, Jesús; Ventanas, Sonia

2014-03-15

132

Compositional shift in lipid fractions during lipid accumulation and turnover in Schizochytrium sp.  

PubMed

Single cell oils (SCOs), a complex lipid system, contains neutral lipids (NLs), polar lipids (PLs) and unsaponifiable matters (UMs). To investigate the dynamic changes and the metabolic competition mechanism of different components of SCOs, changes in lipid composition of Schizochytrium sp. were monitored in lipid accumulation and turnover stages. Lipid content could reach 69.98% in biomass during the lipid accumulation stage, while, after the exhaustion of glucose, the content decreased to 45.51% and 20.6g/L non-oil biomass was synthesis. Polyunsaturated fatty acids (PUFAs) were easier to bind with PLs. NLs were preferentially converted to PLs during lipid turnover stage, accompanied by the degradation of saturated fatty acids and the increase of UMs. Meanwhile, a positive correlation between the synthesis of PUFAs and unsaponifiable matters exited in Schizochytrium sp., and increasing the content of UMs from 45 to 100mg/L could increase the PUFA percentage from 64% to 74% effectively. PMID:24534791

Ren, Lu-Jing; Sun, Guan-Nan; Ji, Xiao-Jun; Hu, Xue-Chao; Huang, He

2014-04-01

133

Serum lipoprotein lipids after gemfibrozil treatment.  

PubMed

The changes of serum lipoprotein lipids including the phospholipids of twelve hyperlipoproteinemic patients were studied after a four weeks treatment with 1200 mg/day gemfibrozil. There was a decrease of all VLDL lipids as well as of LDL and HDL triglycerides and an increase of HDL cholesterol. The phospholipids were influenced in different directions, particularly their concentration in the HDL was constant. The LDL/HDL lipid ratios remained elevated after gemfibrozil. To evaluate the effect of a hypolipidemic drug in more detail, the analysis of the complete lipoprotein lipid moiety and the ratios within and between the lipoproteins would be helpful. PMID:231950

Schwandt, P; Weisweiler, P; Neureuther, G

1979-02-01

134

Dictyostelium Lipid Droplets Host Novel Proteins  

PubMed Central

Across all kingdoms of life, cells store energy in a specialized organelle, the lipid droplet. In general, it consists of a hydrophobic core of triglycerides and steryl esters surrounded by only one leaflet derived from the endoplasmic reticulum membrane to which a specific set of proteins is bound. We have chosen the unicellular organism Dictyostelium discoideum to establish kinetics of lipid droplet formation and degradation and to further identify the lipid constituents and proteins of lipid droplets. Here, we show that the lipid composition is similar to what is found in mammalian lipid droplets. In addition, phospholipids preferentially consist of mainly saturated fatty acids, whereas neutral lipids are enriched in unsaturated fatty acids. Among the novel protein components are LdpA, a protein specific to Dictyostelium, and Net4, which has strong homologies to mammalian DUF829/Tmem53/NET4 that was previously only known as a constituent of the mammalian nuclear envelope. The proteins analyzed so far appear to move from the endoplasmic reticulum to the lipid droplets, supporting the concept that lipid droplets are formed on this membrane. PMID:24036346

Du, Xiaoli; Barisch, Caroline; Paschke, Peggy; Herrfurth, Cornelia; Bertinetti, Oliver; Pawolleck, Nadine; Otto, Heike; Rühling, Harald; Feussner, Ivo; Herberg, Friedrich W.

2013-01-01

135

Lipid regulation of BK channel function  

PubMed Central

This mini-review focuses on lipid modulation of BK (MaxiK, BKCa) current by a direct interaction between lipid and the BK subunits and/or their immediate lipid environment. Direct lipid-BK protein interactions have been proposed for fatty and epoxyeicosatrienoic acids, phosphoinositides and cholesterol, evidence for such action being less clear for other lipids. BK ? (slo1) subunits are sufficient to support current perturbation by fatty and epoxyeicosatrienoic acids, glycerophospholipids and cholesterol, while distinct BK ? subunits seem necessary for current modulation by most steroids. Subunit domains or amino acids that participate in lipid action have been identified in a few cases: hslo1 Y318, cerebral artery smooth muscle (cbv1) R334,K335,K336, cbv1 seven cytosolic CRAC domains, slo1 STREX and ?1 T169,L172,L173 for docosahexaenoic acid, PIP2, cholesterol, sulfatides, and cholane steroids, respectively. Whether these protein motifs directly bind lipids or rather transmit the energy of lipid binding to other areas and trigger protein conformation change remains unresolved. The impact of direct lipid-BK interaction on physiology is briefly discussed. PMID:25202277

Dopico, Alex M.; Bukiya, Anna N.

2014-01-01

136

Lipid nanotubule fabrication by microfluidic tweezing.  

PubMed

There is currently great interest in the development of lipid enclosed systems with complex geometrical arrangements that mimic cellular compartments. With biochemical functionalization, these soft matter devices can be used to probe deeper into life's transport dominated biochemical operations. In this paper, we present a novel tool for machining lipid nanotubules by microfluidic tweezing. A bilayer poly(dimethylsiloxane) (PDMS) device was designed with a lipid reservoir that was loaded by capillary action for lipid film deposition. The lipid reservoir is vertically separated from an upper flow for controlled material wetting and the formation of giant tubule bodies. Three fluidic paths are interfaced for introduction of the giant tubules into the high velocity center of a parabolic flow profile for exposure to hydrodynamic shear stresses. At local velocities approximating 2 mm s (-1), a 300-500 nm diameter jet of lipid material was tweezed from the giant tubule body and elongated with the flow. The high velocity flow provides uniform drag for the rapid and continuous fabrication of lipid nanotubules with tremendous axial ratios. Below a critical velocity, a remarkable shape transformation occurred and the projected lipid tubule grew until a constant 3.6 mum diameter tubule was attained. These lipid tubules could be wired for the construction of advanced lifelike bioreactor systems. PMID:18503287

West, Jonathan; Manz, Andreas; Dittrich, Petra S

2008-06-01

137

START ships lipids across interorganelle space.  

PubMed

The family of StAR related lipid transfer proteins (START) is so-named based on the distinctive capacity for these proteins to transport lipids between membranes. The START domain is a module of about 210 residues, which binds lipids such as glycerolipids, sphingolipids and sterols. This domain has a deep lipid-binding pocket - which shields the hydrophic ligand from the external aqueous environment - covered by a lid. Based on their homology, the fifteen START proteins in mammals have been allocated to six distinct subfamilies, each subfamily being more specialized in the transport and/or sensing of a lipid ligand species. However within the same subgroup, their expression profile and their subcellular localization distinguish them and are critical for their different biological functions. Indeed, START proteins act in a variety of distinct physiological processes, such as lipid transfer between intracellular compartments, lipid metabolism and modulation of signaling events. Mutation or deregulated expression of START proteins is linked to pathological processes, including genetic disorders, autoimmune diseases and cancers. Besides the common single START domain, which is always located at the carboxy-terminal end in mammals, most START proteins harbor additional domains predicted to be critical in favoring lipid exchange. Evidence from well characterized START proteins indicates that these additional domains might be tethering machineries able to bring distinct organelles together and create membrane contact sites prone to lipid exchange via the START domain. PMID:24076129

Alpy, Fabien; Tomasetto, Catherine

2014-01-01

138

Lipid and lipoarabinomannan isolation and characterization.  

PubMed

Mycobacteria are microorganisms that contain a very high content of structurally diverse lipids, some of them being biologically active substances. As such the lipid composition is commonly used to characterize mycobacterial strains at the species and type-species level. This chapter describes the methods that allow the purification of the most commonly isolated biologically active lipids and those used for analyzing extractable lipids and their constituents, cell wall-linked mycolic acids and lipoarabinomannan (LAM). The latter involve simple chromatographic and analytical techniques, such as thin-layer chromatography and gas chromatography coupled to mass spectrometry. PMID:25779311

Lanéelle, Marie-Antoinette; Nigou, Jérôme; Daffé, Mamadou

2015-01-01

139

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

140

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

141

Advances in Intravenous Lipid Emulsions  

Microsoft Academic Search

Over the past decade, our views have\\u000a considerably evolved with respect to the metabolism of intravenous\\u000a lipid emulsions and their composition. Substantial progress has been\\u000a made in understanding the metabolic pathways of emulsion particles and\\u000a the delivery of their various components (fatty acids and vitamins) to\\u000a specific tissues or cells. Although soybean long-chain triglycerides\\u000a represent a valuable source of energy,

2000-01-01

142

Lipid and fatty acid composition of early stages of cephalopods: an approach to their lipid requirements  

Microsoft Academic Search

We report here the main lipid classes and the fatty acid composition from the total lipids of hatchlings of three cephalopod species: Sepia officinalis, Loligo vulgaris and Octopus vulgaris, as well as the lipid composition of two selected crustaceans that have been used previously with success as food resource for rearing cephalopod hatchlings: zoeae of Pagurus prideaux and the mysidacean

Juan C Navarro; Roger Villanueva

2000-01-01

143

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.

144

A simple chromatographic technique for removal of non-lipid contaminants from lipid extracts  

Microsoft Academic Search

SUMMARY A simple procedure for the removal of non-lipid contaminants from lipid extracts is described. The lipids are applied in a line to a silicated paper and eluted in a descending manner into a beaker with 20% methanol in chloroform. The impurities remain on the paper. The procedure, which is carried out in an atmosphere as anhydrous as is practical,

J. J. BIEZENSKI

145

Apparent digestibility of lipid and fatty acids in residual lipids of meals by adult Penaeus monodon  

Microsoft Academic Search

The apparent digestibilities of total lipid, lipid classes and individual fatty acids in the residual lipids from full fat soya, fish, squid, squid liver and fish liver meals were determined to assess the nutritive value of these meals to 20 g Penaeus monodon. Test ingredients were incorporated at 15% substitution levels into a reference diet. Chromic oxide was used as

Zuridah O. Merican; K. F. Shim

1995-01-01

146

Rapid Microfluidic Perfusion Enabling Kinetic Studies of Lipid Ion Channels in a Bilayer Lipid Membrane Chip  

PubMed Central

There is growing recognition that lipids play key roles in ion channel physiology, both through the dynamic formation and dissolution of lipid ion channels and by indirect regulation of protein ion channels. Because existing technologies cannot rapidly modulate the local (bio)chemical conditions at artificial bilayer lipid membranes used in ion channel studies, the ability to elucidate the dynamics of these lipid–lipid and lipid–protein interactions has been limited. Here we demonstrate a microfluidic system supporting exceptionally rapid perfusion of reagents to an on-chip bilayer lipid membrane, enabling the responses of lipid ion channels to dynamic changes in membrane boundary conditions to be probed. The thermoplastic microfluidic system allows initial perfusion of reagents to the membrane in less than 1 s, and enables kinetic behaviors with time constants below 10 s to be directly measured. Application of the platform is demonstrated toward kinetic studies of ceramide, a biologically important lipid known to self-assemble into transmembrane ion channels, in response to dynamic treatments of small ions (La3+) and proteins (Bcl-xL mutant). The results reveal the broader potential of the technology for studies of membrane biophysics, including lipid ion channel dynamics, lipid–protein interactions, and the regulation of protein ion channels by lipid micro domains. PMID:21556947

Shao, Chenren; Sun, Bing; Colombini, Marco; DeVoe, Don L.

2012-01-01

147

AN OVERVIEW OF LIPID NUTRITION WITH EMPHASIS ON ALTERNATIVE LIPID SOURCES IN TILAPIA FEEDS  

Microsoft Academic Search

This paper presents an overview of our current knowledge on the lipid and fatty acid requirements of cultured tilapia. The importance of lipids is discussed with reference to the relatively low levels of lipids currently used in commercial tilapia feeds. The contradictory research results as to the requirement of tilapia for omega-3 and omega-6 polyunsaturated fatty acids (PUFA) are presented

Wing-Keong Ng; Cheong-Yew Chong

148

Characterization of 3D Voronoi tessellation nearest neighbor lipid shells provides atomistic lipid disruption profile of protein containing lipid membranes.  

PubMed

Quantifying protein-induced lipid disruptions at the atomistic level is a challenging problem in membrane biophysics. Here we propose a novel 3D Voronoi tessellation nearest-atom-neighbor shell method to classify and characterize lipid domains into discrete concentric lipid shells surrounding membrane proteins in structurally heterogeneous lipid membranes. This method needs only the coordinates of the system and is independent of force fields and simulation conditions. As a proof-of-principle, we use this multiple lipid shell method to analyze the lipid disruption profiles of three simulated membrane systems: phosphatidylcholine, phosphatidylcholine/cholesterol, and beta-amyloid/phosphatidylcholine/cholesterol. We observed different atomic volume disruption mechanisms due to cholesterol and beta-amyloid. Additionally, several lipid fractional groups and lipid-interfacial water did not converge to their control values with increasing distance or shell order from the protein. This volume divergent behavior was confirmed by bilayer thickness and chain orientational order calculations. Our method can also be used to analyze high-resolution structural experimental data. PMID:25637891

Cheng, Sara Y; Duong, Hai V; Compton, Campbell; Vaughn, Mark W; Nguyen, Hoa; Cheng, Kwan H

2015-03-01

149

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.

150

Clinical controversies in lipid management.  

PubMed

Even though it is firmly established that statins are the cornerstone of management of dyslipidemias, several controversies still exist in this area. In the present review, the most pertinent controversies in lipid management are discussed and the current evidence is summarized. Treatment with statins increases the risk for type 2 diabetes mellitus (T2DM) but this increase appears to be small and outweighed by the benefits of statins on cardiovascular disease prevention. Accordingly, statin treatment-associated T2DM should not affect management decisions. In patients who cannot achieve low-density lipoprotein cholesterol (LDL-C) targets despite treatment with the maximum tolerated dose of a potent statin, adding ezetimibe appears to be the treatment of choice. Finally, patients who achieved LDL-C targets with a statin but have elevated triglyceride levels appear to have increased cardiovascular risk and adding fenofibrate appears to reduce this risk. Even though additional large randomized controlled trials are unlikely to be performed with the existing lipid-lowering agents, mechanistic, genetic and epidemiological studies, as well as careful analyses of the existing trials will provide further insights in these controversial issues and will allow the optimization of the management of dyslipidemia aiming at further reductions in cardiovascular morbidity. PMID:25669164

Tziomalos, K

2015-06-01

151

Efficient conversion of biomass into lipids by using the simultaneous saccharification and enhanced lipid production process  

PubMed Central

Background Microbial lipid production by using lignocellulosic biomass as the feedstock holds a great promise for biodiesel production and biorefinery. This usually involves hydrolysis of biomass into sugar-rich hydrolysates, which are then used by oleaginous microorganisms as the carbon and energy sources to produce lipids. However, the costs of microbial lipids remain prohibitively high for commercialization. More efficient and integrated processes are pivotal for better techno-economics of microbial lipid technology. Results Here we describe the simultaneous saccharification and enhanced lipid production (SSELP) process that is highly advantageous in terms of converting cellulosic materials into lipids, as it integrates cellulose biomass hydrolysis and lipid biosynthesis. Specifically, Cryptococcus curvatus cells prepared in a nutrient-rich medium were inoculated at high dosage for lipid production in biomass suspension in the presence of hydrolytic enzymes without auxiliary nutrients. When cellulose was loaded at 32.3 g/L, cellulose conversion, cell mass, lipid content and lipid coefficient reached 98.5%, 12.4 g/L, 59.9% and 204 mg/g, respectively. Lipid yields of the SSELP process were higher than those obtained by using the conventional process where cellulose was hydrolyzed separately. When ionic liquid pretreated corn stover was used, both cellulose and hemicellulose were consumed simultaneously. No xylose was accumulated over time, indicating that glucose effect was circumvented. The lipid yield reached 112 mg/g regenerated corn stover. This process could be performed without sterilization because of the absence of auxiliary nutrients for bacterial contamination. Conclusions The SSELP process facilitates direct conversion of both cellulose and hemicellulose of lignocellulosic materials into microbial lipids. It greatly reduces time and capital costs while improves lipid coefficient. Optimization of the SSELP process at different levels should further improve the efficiency of microbial lipid technology, which in turn, promote the biotechnological production of fatty acid-derived products from lignocellulosic biomass. PMID:23497564

2013-01-01

152

2011 Plant Lipids: Structure, Metabolism, & Function Gordon Research Conference  

SciTech Connect

This is the second Gordon Research Conference on 'Plant Lipids: Structure, Metabolism & Function'. It covers current topics in lipid structure, metabolism and function in eukaryotic photosynthetic organisms including seed plants, algae, mosses and ferns. Work in photosynthetic bacteria is considered as well as it serves the understanding of specific aspects of lipid metabolism in plants. Breakthroughs are discussed in research on plant lipids as diverse as glycerolipids, sphingolipids, lipids of the cell surface, isoprenoids, fatty acids and their derivatives. The program covers nine concepts at the forefront of research under which afore mentioned plant lipid classes are discussed. The goal is to integrate areas such as lipid signaling, basic lipid metabolism, membrane function, lipid analysis, and lipid engineering to achieve a high level of stimulating interaction among diverse researchers with interests in plant lipids. One Emphasis is on the dynamics and regulation of lipid metabolism during plant cell development and in response to environmental factors.

Christopher Benning

2011-02-04

153

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

154

Do lipids influence the allergic sensitization process?  

PubMed Central

Allergic sensitization is a multifactorial process that is not only influenced by the allergen and its biological function per se but also by other small molecular compounds, such as lipids, that are directly bound as ligands by the allergen or are present in the allergen source. Several members of major allergen families bind lipid ligands through hydrophobic cavities or electrostatic or hydrophobic interactions. These allergens include certain seed storage proteins, Bet v 1–like and nonspecific lipid transfer proteins from pollens and fruits, certain inhalant allergens from house dust mites and cockroaches, and lipocalins. Lipids from the pollen coat and furry animals and the so-called pollen-associated lipid mediators are codelivered with the allergens and can modulate the immune responses of predisposed subjects by interacting with the innate immune system and invariant natural killer T cells. In addition, lipids originating from bacterial members of the pollen microbiome contribute to the outcome of the sensitization process. Dietary lipids act as adjuvants and might skew the immune response toward a TH2-dominated phenotype. In addition, the association with lipids protects food allergens from gastrointestinal degradation and facilitates their uptake by intestinal cells. These findings will have a major influence on how allergic sensitization will be viewed and studied in the future. PMID:24880633

Bublin, Merima; Eiwegger, Thomas; Breiteneder, Heimo

2014-01-01

155

GABA interaction with lipids in organic medium.  

PubMed

The interaction of 3H-GABA (gamma-aminobutyric acid and 14C-glutamate with lipids in an aqueous organic partition system was studied. With this partition system 3H-GABA and 14C-glutamate were able to interact with sphingomyelin, sulfatide, phosphatidylcholine, phosphatidylserine, phosphatidylethanolamine and phosphatidic acid but not with cholesterol or ceramide. In an homogeneous aqueous medium we could not demonstrate any interaction between 3H-GABA and lipids. The apparent dissociation constants (Kd) for 3H-GABA-lipids or 14C-glutamate-lipids interactions in organic medium were in the millimolar range and maximal charge (Bmax) between 3 and 7 moles of GABA or glutamate by mole of lipid. Amino acids such as glutamic acid, beta-alanine and glycine displaced 3H-GABA with the same potency as GABA itself; thus these results show that the interaction lacks pharmacological specificity. To detect this interaction lipid concentrations higher than 2 microM were required and in the partition system 3H-GABA and lipid phosphorus were both concentrated at the interface. Therefore lipids tested with a biphasic partition system do not fulfill the classical criteria for a neurotransmitter receptor at least not for GABA and glutamate. PMID:2886873

Beltramo, D; Kivatinitz, S; Lassaga, E; Arce, A

1987-08-10

156

Do lipids influence the allergic sensitization process?  

PubMed

Allergic sensitization is a multifactorial process that is not only influenced by the allergen and its biological function per se but also by other small molecular compounds, such as lipids, that are directly bound as ligands by the allergen or are present in the allergen source. Several members of major allergen families bind lipid ligands through hydrophobic cavities or electrostatic or hydrophobic interactions. These allergens include certain seed storage proteins, Bet v 1-like and nonspecific lipid transfer proteins from pollens and fruits, certain inhalant allergens from house dust mites and cockroaches, and lipocalins. Lipids from the pollen coat and furry animals and the so-called pollen-associated lipid mediators are codelivered with the allergens and can modulate the immune responses of predisposed subjects by interacting with the innate immune system and invariant natural killer T cells. In addition, lipids originating from bacterial members of the pollen microbiome contribute to the outcome of the sensitization process. Dietary lipids act as adjuvants and might skew the immune response toward a TH2-dominated phenotype. In addition, the association with lipids protects food allergens from gastrointestinal degradation and facilitates their uptake by intestinal cells. These findings will have a major influence on how allergic sensitization will be viewed and studied in the future. PMID:24880633

Bublin, Merima; Eiwegger, Thomas; Breiteneder, Heimo

2014-09-01

157

Spectroscopic evaluation of human tear lipids  

Microsoft Academic Search

Infrared and fluorescence spectroscopies were applied to characterize the molecular conformational\\/structure and dynamics of human meibum (ML) and tear lipids (SSL). ML lipids contained more CC and CH3 moieties than SSL. SSL contained OH groups that were not apparent in the spectra of ML. The CO stretching band observed in the infrared spectra of SSL and ML revealed that the

Douglas Borchman; Gary N. Foulks; Marta C. Yappert; Daxin Tang; Donghai V. Ho

2007-01-01

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

EFFECTS OF LIGHT ON SKIN LIPID METABOLISM  

Microsoft Academic Search

The effects of light on in vitro skin lipid metabolism were examined. Fresh human skin specimens were irradiated with a Xenon lamp at a level equivalent to 10 x the minimal erythema dose. After irradiation the skin specimens were incubated 6 hours in the presence of 14C-acetate. Total lipids were extracted and the levels of acetate incorporation determined. The total

Homer S. Black; Elizabeth W. Rauschkolb

1971-01-01

160

Biosynthesis of archaeal membrane ether lipids  

PubMed Central

A vital function of the cell membrane in all living organism is to maintain the membrane permeability barrier and fluidity. The composition of the phospholipid bilayer is distinct in archaea when compared to bacteria and eukarya. In archaea, isoprenoid hydrocarbon side chains are linked via an ether bond to the sn-glycerol-1-phosphate backbone. In bacteria and eukarya on the other hand, fatty acid side chains are linked via an ester bond to the sn-glycerol-3-phosphate backbone. The polar head groups are globally shared in the three domains of life. The unique membrane lipids of archaea have been implicated not only in the survival and adaptation of the organisms to extreme environments but also to form the basis of the membrane composition of the last universal common ancestor (LUCA). In nature, a diverse range of archaeal lipids is found, the most common are the diether (or archaeol) and the tetraether (or caldarchaeol) lipids that form a monolayer. Variations in chain length, cyclization and other modifications lead to diversification of these lipids. The biosynthesis of these lipids is not yet well understood however progress in the last decade has led to a comprehensive understanding of the biosynthesis of archaeol. This review describes the current knowledge of the biosynthetic pathway of archaeal ether lipids; insights on the stability and robustness of archaeal lipid membranes; and evolutionary aspects of the lipid divide and the LUCA. It examines recent advances made in the field of pathway reconstruction in bacteria. PMID:25505460

Jain, Samta; Caforio, Antonella; Driessen, Arnold J. M.

2014-01-01

161

Altered renal lipid metabolism and renal lipid accumulation in human diabetic nephropathy  

PubMed Central

Animal models link ectopic lipid accumulation to renal dysfunction, but whether this process occurs in the human kidney is uncertain. To this end, we investigated whether altered renal TG and cholesterol metabolism results in lipid accumulation in human diabetic nephropathy (DN). Lipid staining and the expression of lipid metabolism genes were studied in kidney biopsies of patients with diagnosed DN (n = 34), and compared with normal kidneys (n = 12). We observed heavy lipid deposition and increased intracellular lipid droplets. Lipid deposition was associated with dysregulation of lipid metabolism genes. Fatty acid ?-oxidation pathways including PPAR-?, carnitine palmitoyltransferase 1, acyl-CoA oxidase, and L-FABP were downregulated. Downregulation of renal lipoprotein lipase, which hydrolyzes circulating TGs, was associated with increased expression of angiopoietin-like protein 4. Cholesterol uptake receptor expression, including LDL receptors, oxidized LDL receptors, and acetylated LDL receptors, was significantly increased, while there was downregulation of genes effecting cholesterol efflux, including ABCA1, ABCG1, and apoE. There was a highly significant correlation between glomerular filtration rate, inflammation, and lipid metabolism genes, supporting a possible role of abnormal lipid metabolism in the pathogenesis of DN. These data suggest that renal lipid metabolism may serve as a target for specific therapies aimed at slowing the progression of glomerulosclerosis. PMID:24371263

Herman-Edelstein, Michal; Scherzer, Pnina; Tobar, Ana; Levi, Moshe; Gafter, Uzi

2014-01-01

162

Small GTPase Rab40c Associates with Lipid Droplets and Modulates the Biogenesis of Lipid Droplets  

PubMed Central

The subcellular location and cell biological function of small GTPase Rab40c in mammalian cells have not been investigated in detail. In this study, we demonstrated that the exogenously expressed GFP-Rab40c associates with lipid droplets marked by neutral lipid specific dye Oil red or Nile red, but not with the Golgi or endosomal markers. Further examination demonstrated that Rab40c is also associated with ERGIC-53 containing structures, especially under the serum starvation condition. Rab40c is increasingly recruited to the surface of lipid droplets during lipid droplets formation and maturation in HepG2 cells. Rab40c knockdown moderately decreases the size of lipid droplets, suggesting that Rab40c is involved in the biogenesis of lipid droplets. Stimulation for adipocyte differentiation increases the expression of Rab40c in 3T3-L1 cells. Rab40c interacts with TIP47, and is appositionally associated with TIP47-labeled lipid droplets. In addition, over-expression of Rab40c causes the clustering of lipid droplets independent of its GTPase activity, but completely dependent of the intact SOCS box domain of Rab40c. In addition, Rab40c displayed self-interaction as well as interaction with TIP47 and the SOCS box is essential for its ability to induce clustering of lipid droplets. Our results suggest that Rab40c is a novel Rab protein associated with lipid droplets, and is likely involved in modulating the biogenesis of lipid droplets. PMID:23638186

Tan, Ran; Wang, Weijie; Wang, Shicong; Wang, Zhen; Sun, Lixiang; He, Wei; Fan, Rong; Zhou, Yunhe; Xu, Xiaohui; Hong, Wanjin; Wang, Tuanlao

2013-01-01

163

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

164

The Sec14-superfamily and mechanisms for crosstalk between lipid metabolism and lipid signaling  

PubMed Central

Lipid signaling pathways define central mechanisms of cellular regulation. Productive lipid signaling requires an orchestrated coupling0020between lipid metabolism, lipid organization, and the action of protein machines that execute appropriate downstream reactions. Using membrane trafficking control as primary context, we explore the idea that the Sec14-protein superfamily defines a set of modules engineered for the sensing of specific aspects of lipid metabolism and subsequent transduction of ‘sensing’ information to a phosphoinositide-driven ‘execution phase’. In this manner, the Sec14–superfamily connects diverse territories of the lipid metabolome with phosphoinositide signaling in a productive ‘crosstalk’ between these two systems. Mechanisms of crosstalk, where non-enzymatic proteins integrate metabolic cues with the action of interfacial enzymes, represent unappreciated regulatory themes in lipid signaling. PMID:19926291

Bankaitis, Vytas A.; Mousley, Carl J.; Schaaf, Gabriel

2009-01-01

165

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

166

Morphology and interaction between lipid domains  

PubMed Central

Cellular membranes are a heterogeneous mix of lipids, proteins and small molecules. Special groupings enriched in saturated lipids and cholesterol form liquid-ordered domains, known as “lipid rafts,” thought to serve as platforms for signaling, trafficking and material transport throughout the secretory pathway. Questions remain as to how the cell maintains small fluid lipid domains, through time, on a length scale consistent with the fact that no large-scale phase separation is observed. Motivated by these examples, we have utilized a combination of mechanical modeling and in vitro experiments to show that membrane morphology plays a key role in maintaining small domain sizes and organizing domains in a model membrane. We demonstrate that lipid domains can adopt a flat or dimpled morphology, where the latter facilitates a repulsive interaction that slows coalescence and helps regulate domain size and tends to laterally organize domains in the membrane. PMID:19620730

Ursell, Tristan S.; Klug, William S.; Phillips, Rob

2009-01-01

167

Lipid peroxidation of liposome induced by glucosone.  

PubMed

Lipid peroxidation of liposome made of egg lecithin was induced by glucosone (D-arabino-hexos-2-ulose), a secondary product of Maillard reaction or glycation of protein. Lipid peroxidation was assessed with measurement of TBARS (thiobarbituric acid reacting substances), POV (peroxide value), and HPLC measurement of MDA (malondialdehyde). EDTA and DTPA (diethylenetriamine-pentaacetic acid) inhibited the lipid peroxidation assessed by each method described above, indicating involvement of metal ions. The observed reduction of Fe3+ to Fe2+ by glucosone might be a critical step of the lipid peroxidation. Our findings suggest a possible role of lipid peroxidation of low-density lipoproteins (LDL) induced by glucosone in atherosis caused by diabetes mellitus. PMID:1291643

Nakayama, T; Yamada, M; Osawa, T; Kawakishi, S

1992-08-01

168

Lipid-based biofuel production from wastewater.  

PubMed

Increasing world population, urbanization and industrialization are driving global increases in wastewater production. Wastewater comprises significant amounts of chemical energy primarily in the form of organic molecules (in particular lipids), which are currently not being recovered comprehensively. Within biological wastewater treatment (BWWT) systems, specialized microorganisms assimilate and store lipids anaerobically. These intracellular stores represent interesting feedstocks for biofuel synthesis. Here, we review our current understanding of the genetic and functional basis for bacterial lipid accumulation and processing, and relate this to lipid accumulating bacterial populations which occur naturally in BWWT plants. A grand challenge for microbial ecologists and engineers now lies in translating this knowledge into the design of new BWWT processes for the comprehensive recovery of lipids from wastewater streams and their subsequent conversion into biofuel. PMID:24768793

Muller, Emilie E L; Sheik, Abdul R; Wilmes, Paul

2014-12-01

169

Model answers to lipid membrane questions.  

PubMed

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

2011-09-01

170

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

171

[Nitric oxide and lipid peroxidation].  

PubMed

Nitric oxide (NO) is a free radical produced enzymatically in biological systems from the guanidino group of L-arginine. Its large spectrum of biological effects is achieved through chemical interactions with different targets including oxygen (O2), superoxide (O2o-) and other oxygen reactive species (ROS), transition metals and thiols. Superoxide anions and other ROS have been reported to react with NO to produce peroxynitrite anions that can decompose to form nitrogen dioxide (NO2) and hydroxyl radial (OHo). Thus, NO has been reported to have a dual effect on lipid peroxidation (prooxidant via the peroxynitrite or antioxydant via the chelation of ROS). In the present study we have investigated in different models the in vitro and in vivo action of NO on lipid peroxidation. Copper-induced LDL oxidation were used as an in vitro model. Human LDL (100 micrograms ApoB/ml) were incubated in oxygene-saturated PBS buffer in presence or absence of Cu2+ (2.5 microM) with increasing concentrations of NO donnors (sodium nitroprussiate or nitroso-glutathione). LDL oxidation was monitored continuously for conjugated diene formation (234 nm) and 4-hydroxynonenal (HNE) accumulation. Exogenous NO prevents in a dose dependent manner the progress of copper-induced oxidation. Ischaemia-reperfusion injury (I/R), characterized by an overproduction of ROS, is used as an in vivo model. Anaesthetized rats were submitted to 1 hour renal ischaemia following by 2 hours of reperfusion. Sham-operated rats (SOP) were used as control. Lipid peroxidation was evaluated by measuring the HNE accumulated in rats kidneys in presence or absence of L-arginine or D-arginine infusion. L-arginine, but not D-arginine, enhances HNE accumulation in I/R but not in SOP (< 0.050 pmol/g tissue in SOP versus 0.6 nmol/g tissue in I/R), showing that, in this experimental conditions, NO produced from L-arginine, enhances the toxicity of ROS. This study shows that the pro- or antioxydant effects of NO are different in vivo and in vitro and could be driven by environmental conditions such as pH, relative concentrations of NO and ROS, ferryl species. PMID:8673627

Cristol, J P; Maggi, M F; Guérin, M C; Torreilles, J; Descomps, B

1995-01-01

172

Histochemical detection of lipid droplets in cultured cells.  

PubMed

Cells store excess lipid as esters in the form of triglycerides and cholesterol esters. Most lipid esters are compartmentalized in globular structures called lipid droplets. Here we describe several methods of detecting lipid droplets by fluorescence microscopy. Lipid droplets can be visualized either by staining the lipid ester core using fluorescent dyes or by labeling lipid droplet-specific proteins using antibodies. The intracellular distribution of lipid droplets can be analyzed without much difficulty by these methods, but care must be taken to avoid certain pitfalls. PMID:23027019

Suzuki, Michitaka; Shinohara, Yuki; Fujimoto, Toyoshi

2013-01-01

173

Bioactive lipids in pathological retinopathy.  

PubMed

Diabetic retinopathy is a common condition that occurs in patients with diabetes with long-standing hyperglycemia that is characterized by inappropriate angiogenesis. This pathological angiogenesis could be a sort of physiological proliferative response to injury by the endothelium. Recent studies suggested that reactive oxygen species (ROS) play a significant role in this angiogenesis. Vascular endothelial growth factor (VEGF) is a potent angiogenic growth factor that plays a significant role in diabetic retinopathy. The interaction between VEGF and ROS, and theirs in turn with pro- and anti-inflammatory cytokines and anti-inflammatory bioactive lipid molecules such as lipoxins, resolvins, protectins, and maresins is particularly relevant to understand the pathophysiology of diabetic retinopathy and develop future therapeutic interventions. PMID:24188230

Ma, Qi; Shen, Jun-Hui; Shen, Sheng-Rong; Das, Undurti N

2014-01-01

174

Corticosteroid solubility and lipid polarity control release from solid lipid nanoparticles.  

PubMed

Solid lipid nanoparticles (SLN) show promise as a drug delivery system for skin administration. The solid state of the lipid particle enables efficient drug encapsulation and controlled drug release. The present study addresses the influence of lipid composition and drug substance lipid solubility on the in vitro release profile of corticosteroids from SLN for topical administration. Firstly, the effect of lipid composition on the lipid solubility and in vitro release of betamethasone-17-valerate (BMV) was determined by varying the lipid monoglyceride content and the chain length of the fatty acid moiety. Secondly, the effect of drug substance physicochemical properties was determined by studying five different corticosteroid derivatives with different lipophilicity. A high concentration of monoglyceride in SLN increased the amount of BMV released. The corticosteroid release rate depended on the drug substance lipophilicity and it was clear that the release profiles depended on drug partitioning to the aqueous phase as indicated by zero order kinetics. The results emphasize that the corticosteroid solubility in the lipid phase greatly influence drug distribution in the lipid particles and release properties. Thus knowledge of drug substance solubility and lipid polarity contributes to optimize SLN release properties. PMID:19836439

Jensen, Louise B; Magnussson, Emily; Gunnarsson, Linda; Vermehren, Charlotte; Nielsen, Hanne M; Petersson, Karsten

2010-05-01

175

LipidHome: a database of theoretical lipids optimized for high throughput mass spectrometry lipidomics.  

PubMed

Protein sequence databases are the pillar upon which modern proteomics is supported, representing a stable reference space of predicted and validated proteins. One example of such resources is UniProt, enriched with both expertly curated and automatic annotations. Taken largely for granted, similar mature resources such as UniProt are not available yet in some other "omics" fields, lipidomics being one of them. While having a seasoned community of wet lab scientists, lipidomics lies significantly behind proteomics in the adoption of data standards and other core bioinformatics concepts. This work aims to reduce the gap by developing an equivalent resource to UniProt called 'LipidHome', providing theoretically generated lipid molecules and useful metadata. Using the 'FASTLipid' Java library, a database was populated with theoretical lipids, generated from a set of community agreed upon chemical bounds. In parallel, a web application was developed to present the information and provide computational access via a web service. Designed specifically to accommodate high throughput mass spectrometry based approaches, lipids are organised into a hierarchy that reflects the variety in the structural resolution of lipid identifications. Additionally, cross-references to other lipid related resources and papers that cite specific lipids were used to annotate lipid records. The web application encompasses a browser for viewing lipid records and a 'tools' section where an MS1 search engine is currently implemented. LipidHome can be accessed at http://www.ebi.ac.uk/apweiler-srv/lipidhome. PMID:23667450

Foster, Joseph M; Moreno, Pablo; Fabregat, Antonio; Hermjakob, Henning; Steinbeck, Christoph; Apweiler, Rolf; Wakelam, Michael J O; Vizcaíno, Juan Antonio

2013-01-01

176

DNA Release from Lipoplexes by Anionic Lipids: Correlation with Lipid Mesomorphism, Interfacial Curvature, and Membrane Fusion  

PubMed Central

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. PMID:15298910

Tarahovsky, Yury S.; Koynova, Rumiana; MacDonald, Robert C.

2004-01-01

177

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

178

Interfacial & colloidal aspects of lipid digestion.  

PubMed

Amongst the main issues challenging the food manufacturing sector, health and nutrition are becoming increasingly important. Global concerns such as obesity, the ageing population and food security will have to be addressed. Food security is not just about assuring food supply, but is also about optimising nutritional delivery from the food that is available [1]. Therefore one challenge is to optimise the health benefits from the lipids and lipid soluble nutrients. Colloid scientists have an affinity for lipids because they are water insoluble, however this presents a challenge to the digestive system, which has to convert them to structures that are less insoluble so they are available for uptake. Despite this, the human digestive system is remarkably effective at digesting and absorbing most lipids. This is primarily driven through maximising energy intake, as lipids possess the highest calorific value, which was a survival trait to survive times of famine, but is now an underlying cause of obesity in developed countries with high food availability. The critical region here is the lipid-water interface, where the key reactions take place to solubilise lipids and lipid soluble nutrients. Digestive lipases have to adsorb to the oil water interface in order to hydrolyse triacylglycerols into fatty acids and mono glycerides, which accumulate at the interface [2], and inhibit lipase activity. Pancreatic lipase, which is responsible for the majority of lipid hydrolysis, also requires the action of bile salts and colipase to function effectively. Bile salts both aid the adsorption of co-lipase and lipase, and help solubilise the lipolysis products which have accumulated at the interface, into mixed micelles composing bile salts and a range of other lipids, to facilitate transport to the gut mucosal surface prior to uptake and absorption. The process can be affected by the lipid type, as shorter chain, fatty acids are more easily absorbed, whereas the uptake of longer chain fatty acids, particularly the very long chain n-3 fatty acids from fish oils are dependent on source and so may depend on food microstructure for optimal uptake [3]. The uptake of some poorly water soluble nutrients are enhanced by the presence of lipids, but the mechanisms are not clear. In addition, controlling the digestion of lipids can be beneficial as slower release of lipids into the bloodstream can reduce risk of cardiovascular disease, and can promote gut feedback processes that reduce appetite. This presents an opportunity to colloid and interfacial science, as there are many unanswered questions regarding the specific physicochemical mechanisms underlying the process of lipid digestion and uptake. I will review our current knowledge of lipid digestion and present examples of how fundamental research in colloidal and interface science is beginning to address these issues. These include the adsorption behaviour of physiological surfactants such as bile salts; interfacial processes by which different polar lipids can influence lipolysis; and the effect of emulsion based delivery systems on cellular uptake of lipid soluble nutrients. A fundamental understanding of these processes is required if we are to develop intelligent design strategies for foods that will deliver optimal nutrition and improved health benefits in order to address the global challenges facing the food sector in the future. PMID:21377138

Wilde, P J; Chu, B S

2011-06-01

179

Molecular sorting of lipids by bacteriorhodopsin in dilauroylphosphatidylcholine/distearoylphosphatidylcholine lipid bilayers.  

PubMed Central

A combined experimental and theoretical study is performed on binary dilauroylphosphatidylcholine/distearoylphosphatidylcholine (DLPC/DSPC) lipid bilayer membranes incorporating bacteriorhodopsin (BR). The system is designed to investigate the possibility that BR, via a hydrophobic matching principle related to the difference in lipid bilayer hydrophobic thickness and protein hydrophobic length, can perform molecular sorting of the lipids at the lipid-protein interface, leading to lipid specificity/selectivity that is controlled solely by physical factors. The study takes advantage of the strongly nonideal mixing behavior of the DLPC/DSPC mixture and the fact that the average lipid acyl-chain length is strongly dependent on temperature, particularly in the main phase transition region. The experiments are based on fluorescence energy transfer techniques using specifically designed lipid analogs that can probe the lipid-protein interface. The theoretical calculations exploit a microscopic molecular interaction model that embodies the hydrophobic matching as a key parameter. At low temperatures, in the gel-gel coexistence region, experimental and theoretical data consistently indicate that BR is associated with the short-chain lipid DLPC. At moderate temperatures, in the fluid-gel coexistence region, BR remains in the fluid phase, which is mainly composed of short-chain lipid DLPC, but is enriched at the interface between the fluid and gel domains. At high temperatures, in the fluid phase, BR stays in the mixed lipid phase, and the theoretical data suggest a preference of the protein for the long-chain DSPC molecules at the expense of the short-chain DLPC molecules. The combined results of the experiments and the calculations provide evidence that a molecular sorting principle is active because of hydrophobic matching and that BR exhibits physical lipid selectivity. The results are discussed in the general context of membrane organization and compartmentalization and in terms of nanometer-scale lipid-domain formation. Images FIGURE 1 PMID:9336190

Dumas, F; Sperotto, M M; Lebrun, M C; Tocanne, J F; Mouritsen, O G

1997-01-01

180

Lipid nanoscaffolds in carbon nanotube arrays  

NASA Astrophysics Data System (ADS)

We present the fabrication of lipid nanoscaffolds inside carbon nanotube arrays by employing the nanostructural self-assembly of lipid molecules. The nanoscaffolds are finely tunable into model biomembrane-like architectures (planar), soft nanochannels (cylindrical) or 3-dimensionally ordered continuous bilayer structures (cubic). Carbon nanotube arrays hosting the above nanoscaffolds are formed by packing of highly oriented multiwalled carbon nanotubes which facilitate the alignment of lipid nanostructures without requiring an external force. Furthermore, the lipid nanoscaffolds can be created under both dry and hydrated conditions. We show their direct application in reconstitution of egg proteins. Such nanoscaffolds find enormous potential in bio- and nano-technological fields.We present the fabrication of lipid nanoscaffolds inside carbon nanotube arrays by employing the nanostructural self-assembly of lipid molecules. The nanoscaffolds are finely tunable into model biomembrane-like architectures (planar), soft nanochannels (cylindrical) or 3-dimensionally ordered continuous bilayer structures (cubic). Carbon nanotube arrays hosting the above nanoscaffolds are formed by packing of highly oriented multiwalled carbon nanotubes which facilitate the alignment of lipid nanostructures without requiring an external force. Furthermore, the lipid nanoscaffolds can be created under both dry and hydrated conditions. We show their direct application in reconstitution of egg proteins. Such nanoscaffolds find enormous potential in bio- and nano-technological fields. Electronic supplementary information (ESI) available: Additional wide angle X-ray scattering (WAXS) data on the alignment of lipid nanostructures, control and time resolved 2-d images of egg ovalbumin encapsulation and a summary picture of the present work. See DOI: 10.1039/c3nr02068a

Paukner, Catharina; Koziol, Krzysztof K. K.; Kulkarni, Chandrashekhar V.

2013-09-01

181

The Role of Lipids in Retrovirus Replication  

PubMed Central

Retroviruses undergo several critical steps to complete a replication cycle. These include the complex processes of virus entry, assembly, and budding that often take place at the plasma membrane of the host cell. Both virus entry and release involve membrane fusion/fission reactions between the viral envelopes and host cell membranes. Accumulating evidence indicates important roles for lipids and lipid microdomains in virus entry and egress. In this review, we outline the current understanding of the role of lipids and membrane microdomains in retroviral replication. PMID:20740061

Waheed, Abdul A.; Freed, Eric O.

2010-01-01

182

Chemoenzymatic Synthesis of Oligohyaluronan–Lipid Conjugates  

PubMed Central

Herein, we describe an efficient and high-yielding method to synthesize hyaluronan oligosaccharide–lipid conjugates. This strategy is based on first covalently attaching diphytanoyl glycerophosphatidylethanolamine (DiPhPE) to commercially available high molecular weight hyaluronic acid (HA), via the carboxylate group of the glucuronic acid using carbodiimide chemistry. The HA-lipid conjugate mixture is then digested with bovine testicular hyaluronidase to yield HA-DiPhPE conjugates that have a narrow distribution of moderately sized HA oligosaccharides. These HA-lipid conjugates can be incorporated into liposomes or micelles to selectively target CD44 that is overexpressed on many cancer or cancer initiating cells. PMID:24646444

2015-01-01

183

Lipid Partitioning in Maize (Zea mays L.) Endosperm Highlights Relationships among Starch Lipids, Amylose, and Vitreousness.  

PubMed

Content and composition of maize endosperm lipids and their partition in the floury and vitreous regions were determined for a set of inbred lines. Neutral lipids, i.e., triglycerides and free fatty acids, accounted for more than 80% of endosperm lipids and are almost 2 times higher in the floury than in the vitreous regions. The composition of endosperm lipids, including their fatty acid unsaturation levels, as well as their distribution may be related to metabolic specificities of the floury and vitreous regions in carbon and nitrogen storage and to the management of stress responses during endosperm cell development. Remarkably, the highest contents of starch lipids were observed systematically within the vitreous endosperm. These high amounts of starch lipids were mainly due to lysophosphatidylcholine and were tightly linked to the highest amylose content. Consequently, the formation of amylose-lysophosphatidylcholine complexes has to be considered as an outstanding mechanism affecting endosperm vitreousness. PMID:25794198

Gayral, Mathieu; Bakan, Bénédicte; Dalgalarrondo, Michele; Elmorjani, Khalil; Delluc, Caroline; Brunet, Sylvie; Linossier, Laurent; Morel, Marie-Hélène; Marion, Didier

2015-04-01

184

Controlling lipid membrane architecture for tunable nanoplasmonic biosensing.  

PubMed

Tunable nanoplasmonic biosensing for lipid and protein applications is reported based on controlling lipid membrane architecture on surfaces. The interaction of a peptide with lipid membranes is highly sensitive to the membrane architecture on top of plasmonic nanodisks, and the measurement response varies in a manner which is consistent with the surrounding lipid environment. PMID:25079046

Zan, Goh Haw; Jackman, Joshua A; Kim, Seong-Oh; Cho, Nam-Joon

2014-12-10

185

Combined lipid\\/DNA extraction method for environmental samples  

Microsoft Academic Search

Previously, separate methods have been developed for the extraction and purification of lipids and DNA from soils and sediments. This paper describes a new method for the isolation of both lipids and DNA from the same environmental sample. This combined method is based on the Bligh and Dyer lipid extraction technique. Upon phase separation, lipids partition into the organic phase

S. R. Kehrmeyer; B. M. Applegate; H. C. Pinkart; D. B. Hedrick; D. C. White; G. S. Sayler

1996-01-01

186

Lipid vesicles as possible intermediates in the origin of life  

Microsoft Academic Search

Lipid vesicles (liposomes) are closed structures in which (at least) one lipid bilayer separates an aqueous inner compartment from the bulk external aqueous medium, as in membranes of contemporary biological cells. Lipid vesicles have therefore been considered as possible cell precursors during the prebiological era on Earth. Recently, it has been shown that lipid vesicles form spontaneously. Furthermore, it has

Pier Luigi Luisi; Peter Walde; Thomas Oberholzer

1999-01-01

187

A NEW METHOD FOR LIPID EXTRACTION AT AMBIENT TEMPERATURE  

Microsoft Academic Search

A new apparatus for determination of total lipid in food materials was studied by comparing lipid extraction with conventional soxhlet method. Both techniques were tested on different food samples covering a range of lipid contents approximately from 2–55% and found that there were no significant difference (p < 0.05) between the % lipid obtained using two methods. The new method

C. Perera; R. H. Brown

1996-01-01

188

Molecular Packing and Area Compressibility of Lipid Bilayers  

Microsoft Academic Search

Knowledge of the molecular packing of lipids and water in lipid bilayers is important for understanding bilayer mechanics and thermodynamics. Information on packing is most often obtained from x-ray or neutron diffraction measurements. Given the d spacing, composition, and partial specific volumes of the lipid and water, it is a simple matter to calculate the area per lipid molecule, bilayer

Stephen H. White; Glen I. King

1985-01-01

189

Molecular packing and area compressibility of lipid bilayers  

Microsoft Academic Search

Knowledge of the molecular packing of lipids and water in lipid bilayers is important for understanding bilayer mechanics and thermodynamics. Information on packing is most often obtained from x-ray or neutron diffraction measurements. Given the d spacing, composition, and partial specific volumes of the lipid and water, it is a simple matter to calculate the area per lipid molecule, bilayer

S. H. White; G. I. King

1985-01-01

190

The influence of lipid composition on the barrier properties of band 3-containing lipid vesicles  

Microsoft Academic Search

Band 3 protein has been incorporated into lipid vesicles consisting of 94:6 (molar ratio) egg phosphatidylcholine-bovine heart phosphatidylserine or total erythrocyte lipids by means of a Triton X-100 Bio-Beads method, with an additional sonication step prior to the removal of the detergent. This method results, for both types of band 3 lipid vesicles, in rather homogeneous vesicles with comparable protein

P. van Hoogevest; A. P. M. du Maine; B. de Kruijff; J. de Gier

1984-01-01

191

STKE Focus Issue on Lipid Biology: Lipids, Partners in Cellular Signaling  

NSDL National Science Digital Library

This week's issue of Science features a special section called Lipid Biology (http://stke.sciencemag.org/cgi/content/summary/vj_sci;294/5548/1861) that highlights some of the complex and intriguing roles of lipids in numerous processes, including cellular lipid homeostasis, inflammation, vesicle trafficking, angiogenesis, and developmental biology. The diverse nature of these molecules underscores the variety of signaling scenarios in which these molecules participate.

Lisa D. Chong (the American Association for the Advancement of Science; Associate Editor of Science's STKE and Science REV)

2001-12-04

192

Improved Characterization of EV Preparations Based on Protein to Lipid Ratio and Lipid Properties  

PubMed Central

In recent years the study of extracellular vesicles has gathered much scientific and clinical interest. As the field is expanding, it is becoming clear that better methods for characterization and quantification of extracellular vesicles as well as better standards to compare studies are warranted. The goal of the present work was to find improved parameters to characterize extracellular vesicle preparations. Here we introduce a simple 96 well plate-based total lipid assay for determination of lipid content and protein to lipid ratios of extracellular vesicle preparations from various myeloid and lymphoid cell lines as well as blood plasma. These preparations included apoptotic bodies, microvesicles/microparticles, and exosomes isolated by size-based fractionation. We also investigated lipid bilayer order of extracellular vesicle subpopulations using Di-4-ANEPPDHQ lipid probe, and lipid composition using affinity reagents to clustered cholesterol (monoclonal anti-cholesterol antibody) and ganglioside GM1 (cholera toxin subunit B). We have consistently found different protein to lipid ratios characteristic for the investigated extracellular vesicle subpopulations which were substantially altered in the case of vesicular damage or protein contamination. Spectral ratiometric imaging and flow cytometric analysis also revealed marked differences between the various vesicle populations in their lipid order and their clustered membrane cholesterol and GM1 content. Our study introduces for the first time a simple and readily available lipid assay to complement the widely used protein assays in order to better characterize extracellular vesicle preparations. Besides differentiating extracellular vesicle subpopulations, the novel parameters introduced in this work (protein to lipid ratio, lipid bilayer order, and lipid composition), may prove useful for quality control of extracellular vesicle related basic and clinical studies. PMID:25798862

Osteikoetxea, Xabier; Balogh, Andrea; Szabó-Taylor, Katalin; Németh, Andrea; Szabó, Tamás Géza; Pálóczi, Krisztina; Sódar, Barbara; Kittel, Ágnes; György, Bence; Pállinger, Éva; Matkó, János; Buzás, Edit Irén

2015-01-01

193

Lipid peroxides in obese patients and effects of weight loss with orlistat on lipid peroxides levels  

Microsoft Academic Search

OBJECTIVE:Obesity is a well-known risk factor of atherosclerosis. Recent studies showed that obesity is associated with enhanced lipid peroxidation. The aim of this study is to investigate the effect of weight reduction with orlistat treatment on lipid peroxidation levels. We assessed lipid peroxidation by measuring the concentration of plasma malondialdehyde (MDA).DESIGN:A randomized, controlled, open-label 6-month study.SUBJECTS:In total, 36 obese (body

D Yesilbursa; Z Serdar; A Serdar; M Sarac; S Coskun; C Jale

2005-01-01

194

Visualization of the lipid barrier and measurement of lipid pathlength in human stratum corneum  

Microsoft Academic Search

Detailed models of solute transport through the stratum corneum (SC) require an interpretation of apparent bulk diffusion\\u000a coefficients in terms of microscopic transport properties. Modern microscopy techniques provide a tool for evaluating one\\u000a key property—lipid pathway tortuosity—in more detail than previously possible. Microscopic lipid pathway measurements on alkali\\u000a expanded human SC stained with the lipid-soluble dyes methylene blue, Nile red,

Priva S. Talreja; Gerald B. Kasting; Nancy K. Kleene; William L. Pickens; Tsuo-Feng Wang

2001-01-01

195

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

196

Intercellular Lipid Mediators and GPCR Drug Discovery  

PubMed Central

G-protein-coupled receptors (GPCR) are the largest superfamily of receptors responsible for signaling between cells and tissues, and because they play important physiological roles in homeostasis, they are major drug targets. New technologies have been developed for the identification of new ligands, new GPCR functions, and for drug discovery purposes. In particular, intercellular lipid mediators, such as, lysophosphatidic acid and sphingosine 1-phosphate have attracted much attention for drug discovery and this has resulted in the development of fingolimod (FTY-720) and AM095. The discovery of new intercellular lipid mediators and their GPCRs are discussed from the perspective of drug development. Lipid GPCRs for lysophospholipids, including lysophosphatidylserine, lysophosphatidylinositol, lysophosphatidylcholine, free fatty acids, fatty acid derivatives, and other lipid mediators are reviewed. PMID:24404331

Im, Dong-Soon

2013-01-01

197

Bilayer lipid membranes from falling droplets.  

PubMed

We describe a system that provides a rapid and simple way of forming suspended lipid bilayers within a microfluidic platform from an aqueous droplet. Bilayer lipid membranes are created in a polymeric device by contacting monolayers formed at a two-phase liquid-liquid interface. Microdroplets, containing membrane proteins, are injected onto an electrode positioned above an aperture machined through a conical cavity that is filled with a lipid-alkane solution. The formation of the BLM depends solely on the device geometry and leads to spontaneous formation of lipid bilayers simply by dispensing droplets of buffer. When an aqueous droplet containing transmembrane proteins or proteoliposomes is injected, straightforward electrophysiology measurements are possible. This method is suitable for incorporation into lab-on-a-chip devices and allows for buffer exchange and electrical measurements. PMID:19152090

Zagnoni, Michele; Sandison, Mairi E; Marius, Phedra; Morgan, Hywel

2009-03-01

198

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

199

Role of Lipids in Osteoporotic Bone Loss  

E-print Network

the anabolic action of these agents on bone is through theiranabolic effects on bone were originally attributed specifically to statins, it seems that they can also be seen with other lipid-lowering agents.

Gharavi, Nima

2002-01-01

200

New methods for lipid nanoparticles preparation.  

PubMed

Lipid nanoparticles have attracted many researchers during recent years due to the excellent tolerability and advantages compared to liposomes and polymeric nanoparticles. High pressure homogenization is the main technique used to prepare solid lipid nanoparticles (SLN) encapsulating different type of drugs, however this method involves some critical process parameters. For this reason and in order to overcome patented methods, different production techniques for lipid nanoparticles have been widely investigated in recent years (last decade). The paper reviews new methods for lipid nanoparticles preparation, and their recent applications in pharmaceutical field, especially focusing on coacervation, microemulsions templates, supercritical fluid technology, phase-inversion temperature (PIT) techniques. References of the most relevant literature and patents published by various research groups on these fields are provided. PMID:21834772

Corrias, Francesco; Lai, Francesco

2011-09-01

201

Lipid rafts: heterogeneity on the high seas.  

PubMed Central

Lipid rafts are membrane microdomains that are enriched in cholesterol and glycosphingolipids. They have been implicated in processes as diverse as signal transduction, endocytosis and cholesterol trafficking. Recent evidence suggests that this diversity of function is accompanied by a diversity in the composition of lipid rafts. The rafts in cells appear to be heterogeneous both in terms of their protein and their lipid content, and can be localized to different regions of the cell. This review summarizes the data supporting the concept of heterogeneity among lipid rafts and outlines the evidence for cross-talk between raft components. Based on differences in the ways in which proteins interact with rafts, the Induced-Fit Model of Raft Heterogeneity is proposed to explain the establishment and maintenance of heterogeneity within raft populations. PMID:14662007

Pike, Linda J

2004-01-01

202

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

203

Milk lipid globules: control of their size distribution.  

PubMed Central

Micro lipid droplets fuse with each other in vivo to form larger precursors of milk lipid globules. The extent of fusion dictates the size range of lipid globules in milk. A cell-free system in which micro lipid droplet fusion can be induced has been developed. Fusion was promoted by calcium and a protein complex from cytosol. Exogenously supplied gangliosides were potent fusion-promoting agents. Endogenous gangliosides were detected on micro lipid droplet surfaces by immunocytochemical localization. Monoclonal antibody to disialyllactosylceramide (GD3) inhibited micro lipid droplet fusion. These observations are suggestive of a role for gangliosides in micro lipid droplet fusion in situ. Images PMID:3194387

Valivullah, H M; Bevan, D R; Peat, A; Keenan, T W

1988-01-01

204

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

205

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

PubMed Central

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.

2013-01-01

206

PAT proteins, an ancient family of lipid droplet proteins that regulate cellular lipid stores  

PubMed Central

Summary The PAT family of lipid droplet proteins includes 5 members in mammals: perilipin, adipose differentiation-related protein (ADRP), tail-interacting protein of 47 kiloDaltons (TIP47), S3-12, and OXPAT. Members of this family are also present in evolutionarily distant organisms, including insects, slime molds and fungi. All PAT proteins share sequence similarity and the ability to bind intracellular lipid droplets, either constitutively or in response to metabolic stimuli, such as increased lipid flux into or out of lipid droplets. Positioned at the lipid droplet surface, PAT proteins manage access of other proteins (lipases) to the lipid esters within the lipid droplet core and can interact with cellular machinery important for lipid droplet biogenesis. Genetic variations in the gene for the best characterized of the mammalian PAT proteins, perilipin, have been associated with metabolic phenotypes, including type 2 diabetes mellitus and obesity. In this review, we discuss how the PAT proteins regulate cellular lipid metabolism both in mammals and in model organisms. PMID:19375517

Bickel, Perry E.; Tansey, John T.; Welte, Michael A.

2009-01-01

207

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)

2008-06-07

208

ATF4 regulates lipid metabolism and thermogenesis  

Microsoft Academic Search

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

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

2010-01-01

209

Serum lipid levels in seasonal affective disorder  

Microsoft Academic Search

Previous research has assessed the relationship between blood lipid levels and depression with contradictory results. Several\\u000a studies have linked low cholesterol levels with impulsive, aggressive and suicidal behaviours. The aim of this pilot study\\u000a was to examine serum lipids in a sample of patients suffering from seasonal affective disorder (SAD). We conducted a retrospective\\u000a analysis of data on total serum

Edda Pjrek; Dietmar Winkler; David W. Abramson; Anastasios Konstantinidis; Jürgen Stastny; Matthäus Willeit; Nicole Praschak-Rieder; Siegfried Kasper

2007-01-01

210

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

211

Treating lipids in cardiovascular disease: new directions  

Microsoft Academic Search

Aims To review the importance of lipid parameters beside low-density lipoprotein (LDL) levels as risk factors for cardiovascular disease, and their potential as therapeutic targets for lipid-lowering agents. Methods and Results Large numbers of studies have shown that, as well as high low-density lipoprotein (LDL) levels, low high-density lipoprotein (HDL) levels and a high LDL\\/HDL ratio are important cardiovascular disease

O. Wiklund

2001-01-01

212

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

213

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

214

Fatty acids of plant vacuolar membrane lipids  

Microsoft Academic Search

Fatty acid (FA) composition of vacuolar membrane lipids from storage tissues of umbelliferous plants, viz., parsnip (Pastinaca sativa L.), parsley (Petroselinium crispum L.), and carrot (Daucus carota L.) is studied by gas-liquid chromatography and the FA biosynthetic pathways are considered. Vacuolar membrane lipids are\\u000a characterized by high (78% of the total FA pool) content of unsaturated FA among which linoleic

S. P. Makarenko; T. A. Konenkina; L. V. Dudareva

2007-01-01

215

Lipids of the Plant Plasma Membrane  

Microsoft Academic Search

\\u000a The plasma membrane (PM) is arguably the most diverse membrane of the plant cell. Furthermore, the protein and lipid composition\\u000a of the PM varies with cell type, developmental stage, and environment. Physical properties of lipids and associate proteins\\u000a allow the formation of a barrier that is selectively permeable to macromolecules and solutes. As the plasma membrane delineates\\u000a the interface between

Fabienne Furt; Françoise Simon-Plas; Sébastien Mongrand

216

Lipid of sunflower seeds produced in japan  

Microsoft Academic Search

The fatty acid composition and tocopherol content of sunflower seeds from experimental plantings in Japan were determined.\\u000a Lipid content of sunflower seed was almost the same irrespective of the variety and the average lipid content was 38.8%. The\\u000a saturated fatty acids were low and the combined percentage of linoleic acid and oleic acid was ca. 90%. The ratio of oleic

Akihiko Nagao; Megumi Yamazaki

1983-01-01

217

Mimicking anhydrobiosis on solid supported lipid bilayers  

E-print Network

MIMICKING ANHYDROBIOSIS ON SOLID SUPPORTED LIPID BILAYERS A Thesis by VANESSA ALYSS CHAPA Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree... of MASTER OF SCIENCE May 2006 Major Subject: Chemistry MIMICKING ANHYDROBIOSIS ON SOLID SUPPORTED LIPID BILAYERS A Thesis by VANESSA ALYSS CHAPA Submitted to the Office of Graduate Studies of Texas A...

Chapa, Vanessa Alyss

2007-09-17

218

Chemical Structure of Bacteriovorax stolpii Lipid A  

Microsoft Academic Search

Bdellovibrionales is a phylogenetically diverse group of predatory prokaryotes, which consists of the two families Bdellovibrionaceae and Bacteriovoracaceae. We describe LPS and lipid A of the type strain Bacteriovorax stolpii DSM 12778, representing the first characterized endotoxin of a Bacteriovoracaceae member. It has a smooth form LPS, which was identified by SDS-polyacrylamide gel electrophoresis. The lipid A structure was\\u000a determined

Sebastian Beck; Frederic D. Müller; Eckhard Strauch; Lothar Brecker; Michael W. Linscheid

2010-01-01

219

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

220

Spastin Binds to Lipid Droplets and Affects Lipid Metabolism  

PubMed Central

Mutations in SPAST, encoding spastin, are the most common cause of autosomal dominant hereditary spastic paraplegia (HSP). HSP is characterized by weakness and spasticity of the lower limbs, owing to progressive retrograde degeneration of the long corticospinal axons. Spastin is a conserved microtubule (MT)-severing protein, involved in processes requiring rearrangement of the cytoskeleton in concert to membrane remodeling, such as neurite branching, axonal growth, midbody abscission, and endosome tubulation. Two isoforms of spastin are synthesized from alternative initiation codons (M1 and M87). We now show that spastin-M1 can sort from the endoplasmic reticulum (ER) to pre- and mature lipid droplets (LDs). A hydrophobic motif comprised of amino acids 57 through 86 of spastin was sufficient to direct a reporter protein to LDs, while mutation of arginine 65 to glycine abolished LD targeting. Increased levels of spastin-M1 expression reduced the number but increased the size of LDs. Expression of a mutant unable to bind and sever MTs caused clustering of LDs. Consistent with these findings, ubiquitous overexpression of Dspastin in Drosophila led to bigger and less numerous LDs in the fat bodies and increased triacylglycerol levels. In contrast, Dspastin overexpression increased LD number when expressed specifically in skeletal muscles or nerves. Downregulation of Dspastin and expression of a dominant-negative variant decreased LD number in Drosophila nerves, skeletal muscle and fat bodies, and reduced triacylglycerol levels in the larvae. Moreover, we found reduced amount of fat stores in intestinal cells of worms in which the spas-1 homologue was either depleted by RNA interference or deleted. Taken together, our data uncovers an evolutionarily conserved role of spastin as a positive regulator of LD metabolism and open up the possibility that dysfunction of LDs in axons may contribute to the pathogenesis of HSP. PMID:25875445

Papadopoulos, Chrisovalantis; Orso, Genny; Mancuso, Giuseppe; Herholz, Marija; Gumeni, Sentiljana; Tadepalle, Nimesha; Jüngst, Christian; Tzschichholz, Anne; Schauss, Astrid; Höning, Stefan; Trifunovic, Aleksandra; Daga, Andrea; Rugarli, Elena I.

2015-01-01

221

Persistence of virus lipid signatures upon silicification  

NASA Astrophysics Data System (ADS)

To date there is no known evidence of viruses within the rock record. Their small size and absence of a metabolism has led to the hypothesis that they lack unique biological signatures, and the potential to become preserved. Biosignature research relevant to early Earth has focused on prokaryotic communities; however, the most abundant member of modern ecosystems, viruses, have been ignored. In order to establish a baseline for research on virus biosignatures, we have initiated laboratory research on known lipid-containing viruses. PRD1 is a lipid-containing virus that infects and replicates in Salmonella typhimurium LT2. PRD1 is a 65 nm spherical virus with an internal lipid membrane, which is a few nanometers thick. When the PRD1 virus stock was mixed with a 400 ppm SiO2 (final concentration) solution and incubated for six months. Fourier Transform Infrared Spectroscopy and lipid analysis using gas chromatography revealed that the virus lipids were still detectable despite complete removal of dissolved silica. Free fatty acids were also detected. Titers of infectious PRD1 viruses after six months in the presence of silica decreased 40 times more than without silica. Though virus biosignature research is in its incipient stages, the data suggest that virus lipid signatures are preserved under laboratory conditions and may offer the potential for contribution to the organic geochemical record.

Kyle, J.; Jahnke, L. L.; Stedman, K. M.

2011-12-01

222

Exploratory studies of lipid-pectin interactions.  

PubMed

This study was undertaken to elucidate the mechanism responsible for the hypolipidemic action of pectin. The experiments reported here were designed to test if direct molecular interactions exist between pectin and lipids. Equilibrium dialysis of pectin and taurocholate showed binding only at high nonphysiological ionic strength. When lipid microemulsions and micelles of low charge density were used, unambiguous proof of binding to pectin were obtained by NMR spectroscopy and gel exclusion chromatography. The results suggest that the interaction in mainly by hydrogen bonds involving the pectin carboxylic moieties. The quantitation of lipid binding by pectin could be established only in presence of polyvalent cations using a membrane filtration technique. Under optimum conditions, pectin can bind four times its weight in lipids. Although the techniques presented here are physical-chemical, the conclusions are highly relevant to bioavailability. These results represent the first successful demonstration of direct lipid-polysaccharide interactions in biochemistry, and they have an obvious bearing on the physiological absorption process. The intestinal binding of dietary and biliary lipids by pectin may be a major mechanism of action of this hypolipidemic polysaccharide. This paper also cells attention to techniques which could be beneficial for the in vitro evaluation of plant fibers. PMID:7054465

Falk, J D; Nagyvary, J J

1982-01-01

223

Binding of cationic lipids to milk ?-lactoglobulin.  

PubMed

We determined the bindings of several lipids such as cholesterol (CHOL), 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP), dioctadecyldimethyl-ammoniumbromide (DDAB), and dioleoylphosphatidylethanolamine (DOPE) to ?-lactoglobulin (?-LG) at physiological conditions. FTIR, CD, and fluorescence spectroscopic methods as well as molecular modeling were used to determine the binding of lipid-protein complexes. Structural analysis showed that lipids bind ?-LG via both hydrophilic and hydrophobic interactions with overall binding constants of K(CHOL-?-LG) = 6.0 (±0.6) × 10(3) M(-1), K(DOPE-?-LG) = 6.5 (±0.7) × 10(3) M(-1), K(DDAB-?-LG) = 1.6 (±0.3) × 10(4) M(-1), and K(DOTAP-?-LG) = 2.2 (±0.67) × 10(4) M(-1). The number of lipid bound per protein molecule (n) was 0.8 (CHOL), 0.7 (DOPE), 1.0 (DDAB), and 1.3 (DOTAP). Molecular modeling showed the participation of several amino acid residues in lipid-protein complexation with the order of binding DOTAP > DDAB > DOPE > CHOL. Alterations of the protein conformation were observed in the presence of lipids with a minor decrease in ?-sheet and an increase in turn structure. PMID:21542594

Hasni, Imed; Bourassa, Philippe; Tajmir-Riahi, Heidar-Ali

2011-05-26

224

Interaction of C(60) fullerene with lipids.  

PubMed

Unsaturated lipids when exposed to air at room temperature undergo a slow autoxidation. When fullerene C(60) was dissolved in selected lipids (ethyl oleate, ethyl linoleate, linseed oil and castor oil) the spectrophotometric analysis shows that the oxidation is concentrated to C(60) which is converted to an epoxide C(60)O. Thus, fullerene C(60) displays antioxidant activity not only when dissolved in unsaturated lipids but also, more generally, when dissolved in unsaturated solvents subjected to autoxidation like, for example, in cyclohexene. The behaviour of C(60) in ethyl oleate has been compared with that of the known antioxidant TMPPD (N,N',N,N,'-tetramethyl-p-phenylenediamine) in ethyl oleate. The mechanism of the antioxidant action of C(60) in lipids has been proposed. The kinetics of C(60) oxidation in lipids was determined spectrophotometrically both at room temperature in the dark and under UV irradiation. The oxidized products derived from C(60) photo-oxidation in lipids have been identified. PMID:20338159

Cataldo, Franco

2010-06-01

225

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

226

Lipids and cell death in yeast  

PubMed Central

Understanding lipid-induced malfunction represents a major challenge of today's biomedical research. The connection of lipids to cellular and organ dysfunction, cell death, and disease (often referred to as lipotoxicity) is more complex than the sole lipotoxic effects of excess free fatty acids and requires genetically tractable model systems for mechanistic investigation. We herein summarize recent advances in the field of lipid-induced toxicity that employ the established model system for cell death and aging research of budding yeast Saccharomyces cerevisiae. Studies in yeast have shed light on various aspects of lipotoxicity, including free fatty acid toxicity, sphingolipid-modulated cell death as well as the involvement of cardiolipin and lipid peroxidation in the mitochondrial pathways of apoptosis. Regimens used range from exogenously applied lipids, genetic modulation of lipolysis and triacylglyceride synthesis, variations in sphingolipid/ceramide metabolism as well as changes in peroxisome function by either genetic or pharmacological means. In future, the yeast model of programmed cell death will further contribute to the clarification of crucial questions of lipid-associated malfunction. PMID:24119111

Eisenberg, Tobias; Büttner, Sabrina

2014-01-01

227

Algal lipids and effect of the environment on their biochemistry  

Microsoft Academic Search

\\u000a Lipids play a number of roles in living organisms and can be divided into two main groups: the nonpolar lipids (acylglycerols,\\u000a sterols, free (nonesterified) fatty acids, wax, and steryl esters) and polar lipids (phosphoglycerides, glycosylglycerides).\\u000a Polar lipids and sterols are important structural components of cell membranes which act as a selective permeable barrier\\u000a for cells and organelles. These lipids maintain

Irina A. Guschina; John L. Harwood

228

Composition, accumulation and utilization of yolk lipids in teleost fish  

Microsoft Academic Search

Lipid reserves in teleost eggs are stored in lipoprotein yolk and, in some species, a discrete oil globule. Lipoprotein yolk lipids are primarily polar lipids, especially phosphatidylcholine and phosphatidylethanolamine (PE), and are rich in (n-3) polyunsaturated fatty acids, especially 22:6(n-3) (docosahexaenoic acid, DHA). Oil consists of neutral lipids and is rich in monounsaturated fatty acids (MUFA). Egg lipids are derived

Murray D. Wiegand

1996-01-01

229

Microalgal lipids biochemistry and biotechnological perspectives.  

PubMed

In the last few years, there has been an intense interest in using microalgal lipids in food, chemical and pharmaceutical industries and cosmetology, while a noteworthy research has been performed focusing on all aspects of microalgal lipid production. This includes basic research on the pathways of solar energy conversion and on lipid biosynthesis and catabolism, and applied research dealing with the various biological and technical bottlenecks of the lipid production process. In here, we review the current knowledge in microalgal lipids with respect to their metabolism and various biotechnological applications, and we discuss potential future perspectives. The committing step in fatty acid biosynthesis is the carboxylation of acetyl-CoA to form malonyl-CoA that is then introduced in the fatty acid synthesis cycle leading to the formation of palmitic and stearic acids. Oleic acid may also be synthesized after stearic acid desaturation while further conversions of the fatty acids (i.e. desaturations, elongations) occur after their esterification with structural lipids of both plastids and the endoplasmic reticulum. The aliphatic chains are also used as building blocks for structuring storage acylglycerols via the Kennedy pathway. Current research, aiming to enhance lipogenesis in the microalgal cell, is focusing on over-expressing key-enzymes involved in the earlier steps of the pathway of fatty acid synthesis. A complementary plan would be the repression of lipid catabolism by down-regulating acylglycerol hydrolysis and/or ?-oxidation. The tendency of oleaginous microalgae to synthesize, apart from lipids, significant amounts of other energy-rich compounds such as sugars, in processes competitive to lipogenesis, deserves attention since the lipid yield may be considerably increased by blocking competitive metabolic pathways. The majority of microalgal production occurs in outdoor cultivation and for this reason biotechnological applications face some difficulties. Therefore, algal production systems need to be improved and harvesting systems need to be more effective in order for their industrial applications to become more competitive and economically viable. Besides, a reduction of the production cost of microalgal lipids can be achieved by combining lipid production with other commercial applications. The combined production of bioactive products and lipids, when possible, can support the commercial viability of both processes. Hydrophobic compounds can be extracted simultaneously with lipids and then purified, while hydrophilic compounds such as proteins and sugars may be extracted from the defatted biomass. The microalgae also have applications in environmental biotechnology since they can be used for bioremediation of wastewater and to monitor environmental toxicants. Algal biomass produced during wastewater treatment may be further valorized in the biofuel manufacture. It is anticipated that the high microalgal lipid potential will force research towards finding effective ways to manipulate biochemical pathways involved in lipid biosynthesis and towards cost effective algal cultivation and harvesting systems, as well. PMID:25449285

Bellou, Stamatia; Baeshen, Mohammed N; Elazzazy, Ahmed M; Aggeli, Dimitra; Sayegh, Fotoon; Aggelis, George

2014-12-01

230

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

231

Red clover polyphenol oxidase and lipid metabolism.  

PubMed

Increasing the polyunsaturated fatty acid (PUFA) composition of milk is acknowledged to be of benefit to consumer health. Despite the high PUFA content of forages, milk fat contains only about 3% of PUFA and only about 0.5% of n-3 fatty acids. This is mainly due to intensive lipid metabolism in the rumen (lipolysis and biohydrogenation) and during conservation (lipolysis and oxidation) such as drying (hay) and ensiling (silage). In red clover, polyphenol oxidase (PPO) has been suggested to protect lipids against degradation, both in the silage as well as in the rumen, leading to a higher output of PUFA in ruminant products (meat and milk). PPO mediates the oxidation of phenols and diphenols to quinones, which will readily react with nucleophilic binding sites. Such binding sites can be found on proteins, resulting in the formation of protein-bound phenols. This review summarizes the different methods that have been used to assess PPO activity in red clover, and an overview on the current understanding of PPO activity and activation in red clover. Knowledge on these aspects is of major importance to fully harness PPO's lipid-protecting role. Furthermore, we review the studies that evidence PPO-mediated lipid protection and discuss its possible importance in lab-scale silages and further in an in vitro rumen system. It is demonstrated that high (induction of) PPO activity can lead to lower lipolysis in the silage and lower biohydrogenation in the rumen. There are three hypotheses on its working mechanism: (i) protein-bound phenols could directly bind to enzymes (e.g. lipases) as such inhibiting them; (ii) binding of quinones in and between proteins embedded in a lipid membrane (e.g. in the chloroplast) could lead to encapsulation of the lipids; (iii) direct binding of quinones to nucleophilic sites in polar lipids also could lead to protection. There is no exclusive evidence on which mechanism is most important, although there are strong indications that only lipid encapsulation in protein-phenol complexes would lead to an effective protection of lipids against ruminal biohydrogenation. From several studies it has also become apparent that the degree of PPO activation could influence the mode and degree of protection. In conclusion, this review demonstrates that protein-bound phenols and encapsulation in protein-phenol complexes, induced by PPO-mediated diphenol oxidation, could be of interest when aiming to protect lipids against pre-ruminal and ruminal degradation. PMID:22439947

Van Ranst, G; Lee, M R F; Fievez, V

2011-02-01

232

Lipids of nervous tissue: composition and metabolism.  

PubMed

As indicated in the Introduction, the many significant developments in the recent past in our knowledge of the lipids of the nervous system have been collated in this article. That there is a sustained interest in this field is evident from the rather long bibliography which is itself selective. Obviously, it is not possible to summarize a review in which the chemistry, distribution and metabolism of a great variety of lipids have been discussed. However, from the progress of research, some general conclusions may be drawn. The period of discovery of new lipids in the nervous system appears to be over. All the major lipid components have been discovered and a great deal is now known about their structure and metabolism. Analytical data on the lipid composition of the CNS are available for a number of species and such data on the major areas of the brain are also at hand but information on the various subregions is meagre. Such investigations may yet provide clues to the role of lipids in brain function. Compared to CNS, information on PNS is less adequate. Further research on PNS would be worthwhile as it is amenable for experimental manipulation and complex mechanisms such as myelination can be investigated in this tissue. There are reports correlating lipid constituents with the increased complexity in the organization of the nervous system during evolution. This line of investigation may prove useful. The basic aim of research on the lipids of the nervous tissue is to unravel their functional significance. Most of the hydrophobic moieties of the nervous tissue lipids are comprised of very long chain, highly unsaturated and in some cases hydroxylated residues, and recent studies have shown that each lipid class contains characteristic molecular species. Their contribution to the properties of neural membranes such as excitability remains to be elucidated. Similarly, a large proportion of the phospholipid molecules in the myelin membrane are ethanolamine plasmalogens and their importance in this membrane is not known. It is firmly established that phosphatidylinositol and possibly polyphosphoinositides are involved with events at the synapse during impulse propagation, but their precise role in molecular terms is not clear. Gangliosides, with their structural complexity and amphipathic nature, have been implicated in a number of biological events which include cellular recognition and acting as adjuncts at receptor sites. More recently, growth promoting and neuritogenic functions have been ascribed to gangliosides. These interesting properties of gangliosides wIll undoubtedly attract greater attention in the future.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:3916238

Sastry, P S

1985-01-01

233

Cellular Lipid Metabolism and the Role of Lipids in Progressive Renal Disease  

Microsoft Academic Search

Dyslipidemia contributes to the rate of progression of atherosclerosis and chronic kidney disease. Also, chronic kidney disease leads to the development of secondary abnormalities in lipid metabolism that contribute to increased cardiovascular morbidity and mortality. This review presents the mechanisms that underlie this risk. The mechanisms of normal cellular lipid metabolism and the abnormalities that develop in association with inflammation

Christine K. Abrass

2004-01-01

234

Serum Lipids, Lipoproteins, and Lipid Metabolizing Enzymes in Identical Twins Discordant for Obesity  

Microsoft Academic Search

Obesity is associated with adverse changes in plasma lipoprotein metabolism, but it is not known completely how this association is modified by genetic factors. We assessed the contribution of obesity to serum lipid and lipoprotein levels and lipid metabolizing enzyme activities by examining 23 identical twin pairs (9 male, 14 female) who had, on the average, an 18-kg intrapair difference

TAPANI RONNEMAA; JUKKA MARNIEMI; MARKKU J. SAVOLAINEN; Y. ANTERO KESANIEMI; CHRISTIAN EHNHOLM; CLAUDE BOUCHARD; MARKKU KOSKENVUO

2010-01-01

235

Incorporation of liquid lipid in lipid nanoparticles for ocular drug delivery enhancement  

NASA Astrophysics Data System (ADS)

The present work investigates the effect of liquid lipid incorporation on the physicochemical properties and ocular drug delivery enhancement of nanostructured lipid carriers (NLCs) and attempts to elucidate in vitro and in vivo the potential of NLCs for ocular drug delivery. The CyA-loaded or fluorescein-marked nanocarriers composed of Precifac ATO 5 and Miglyol 840 (as liquid lipid) were prepared by melting-emulsion technology, and the physicochemical properties of nanocarriers were determined. The uptake of nanocarriers by human corneal epithelia cell lines (SDHCEC) and rabbit cornea was examined. Ex vivo fluorescence imaging was used to investigate the ocular distribution of nanocarriers. The in vitro cytotoxicity and in vivo acute tolerance were evaluated. The higher drug loading capacity and improved in vitro sustained drug release behavior of lipid nanoparticles was found with the incorporation of liquid lipid in lipid nanoparticles. The uptake of nanocarriers by the SDHCEC was increased with the increase in liquid lipid loading. The ex vivo fluorescence imaging of the ocular tissues indicated that the liquid lipid incorporation could improve the ocular retention and penetration of ocular therapeutics. No alternation was macroscopically observed in vivo after ocular surface exposure to nanocarriers. These results indicated that NLC was a biocompatible and potential nanocarrier for ocular drug delivery enhancement.

Shen, Jie; Sun, Minjie; Ping, Qineng; Ying, Zhi; Liu, Wen

2010-01-01

236

Dietary practices and lipid intake in relation to plasma lipid profile in Hong Kong Chinese  

Microsoft Academic Search

Objective: To study dietary lipid intake and plasma lipid profile of the Hong Kong Chinese population as part of a territory wide survey on cardiovascular risk factors. Design: Randomised age and sex stratified survey. Subjects: 1010 subjects aged 25–74 y (500 men, 510 women). Measurements: A food frequency method with food tables compiled for Hong Kong was used for nutrient

J Woo; SSF Leung; SC Ho; A Sham; TH Lam; ED Janus

1997-01-01

237

Lipid A, the lipid component of bacterial lipopolysaccharides: Relation of chemical structure to biological activity  

Microsoft Academic Search

Summary Lipopolysaccharides are integral components of the outer membrane of Gram-negative bacteria and they participate in various membrane functions essential for bacterial growth and survival. Lipopolysaccharides also represent the endotoxins of Gram-negative bacteria and possibly play a role for the pathogenesis and manifestations of bacterial infections. These biological activities are mediated mainly by the lipid component of lipopolysaccharides, termed lipid

Ernst Th. Rietschel; Horst-Werner Wollenweber; Ulrich Zähringer; Otto Lüderitz

1982-01-01

238

http://my.clevelandclinic.org/heart/services/tests/labtests/lipid.aspx Lipid Blood Tests  

E-print Network

http://my.clevelandclinic.org/heart/services/tests/labtests/lipid.aspx Lipid Blood Tests Total of heart and blood vessel disease. · See also Blood Tests to Determine Risk of Coronary Artery Disease Cholesterol (TC) Directly linked to risk of heart and blood vessel disease. Goal values: · 75-169 mg

Cooper, Robin L.

239

Skin diseases associated with the depletion of stratum corneum lipids and stratum corneum lipid substitution therapy.  

PubMed

The skin is the largest organ of the body, whose main function is to protect the body against the loss of physiologically important components as well as harmful environmental insults. From the inside to the outside, the skin comprises three major structural layers: the hypodermis, the dermis and the epidermis. The epidermis contains four different sublayers, the stratum corneum (SC), stratum granulosum, stratum spinosum and stratum basale, where the barrier function of the skin mainly lies in the outermost layer of the epidermis, the SC. The SC contains corneocytes that are embedded in a lipid matrix existing in the form of lipid bilayers. The lipid bilayers are formed mainly from ceramides, free fatty acids and cholesterol, constitute the only continuous pathway across the SC and are responsible for the barrier function of the skin. However, the depletion or disturbance of SC lipids in the SC leads to a perturbation of the barrier function of the skin, and, conversely, several skin diseases such as psoriasis and atopic dermatitis are associated with the depletion of these SC lipids. Therefore, it is of paramount importance to understand the interrelationship between the depletion of SC lipids and skin diseases as well as factors that affect the composition and organization of SC lipids in order to assess the potential benefit of a direct replacement of the missing SC lipids as a means of treating affected, aged or diseased skin. PMID:25196193

Sahle, Fitsum F; Gebre-Mariam, Tsige; Dobner, Bodo; Wohlrab, Johannes; Neubert, Reinhard H H

2015-01-01

240

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

Koldsø, Heidi; Shorthouse, David; Hélie, Jean; Sansom, Mark S. P.

2014-01-01

241

Phase Behavior of Mixed Lipid Bilayered System  

NSDL National Science Digital Library

Lipid mixtures of short and long amphiphile chains self-assemble in water to form a great variety of structures. The morphology of these structures include phases composed of extended flexible bilayer membrane that may display order by stacking with a periodicity as in the anisotropic lamellar phase, or they may also form bilayered miscelles (or bicelles), bilayered disks formed of a long lipid chain with their edges stabilized by short chain lipid, with diameter of a few hundred angstroms. The lipid mixtures have a great potential in the study of membrane proteins and peptides. These mixtures imitate the physical properties of biological membranes and they are stable over a wide range of temperatures, pH and ionic strength. By having a detailed description of the morphology of the lipid mixtures and understanding their phases will help increase their use in various structural biology techniques. Our goal was to study the effect on transition between the bicelle to lamellar phase by changing the concentration of lipid in the solution. Each sample consisted of molar ratios of DHPC:DMPC:DMPG of 0.2:1:0.067. The concentration of lipid was of 20%, 10% and 5%. The 20% sample has a liquid to gel phase transition temperature of near 25°C. The lamellar phase forms above 25°C. By lowering the sample’s concentration and by an isotropic substitution of H2O by D2O, we found some intriguing results: the liquid to gel phase transition and lamellar phase temperature shifted. SANS, reflectometry and crossed polarizers were use to study the transition between the bicelle to lamellar phase. With these results, the structure of the phase boundary between the bicelles and lamellar morphology was better understood and characterized.

Rodriguez-Rivera, Veronica

2005-01-01

242

Lipid Crystallization in Senescent Membranes from Cotyledons  

PubMed Central

Lipid transition temperatures for rough and smooth microsomal membranes isolated from bean (Phaseolus vulgaris) cotyledon tissue at various stages of germination were determined by wide angle x-ray diffraction. The transition temperatures were established by recording diffraction patterns through a temperature series until a sharp x-ray reflection centered at a Bragg spacing of 4.15 Å and denoting the presence of crystalline lipid was discernible. For rough and smooth microsomes from 2-day-old tissue, the transitions occurred at 0 C and 3 C, respectively, indicating that at this early stage in the germination sequence the membrane lipid is entirely liquid-crystalline at physiological temperature. By the 4th day of germination, the transition temperatures had increased to 32 C for smooth microsomes and 35 C for rough microsomes, indicating that at 29 C, which was the growth temperature, portions of the membrane lipid were crystalline. During the later stages of germination, the transition temperature for smooth microsomes continued to rise through 44 C at day 7 to 56 C at day 9, by which time the cotyledons were extensively senescent and beginning to abscise. There was also a dramatic increase in the proportion of membrane lipid in the crystalline phase at 29 C. By contrast, the rough microsomes showed little change in transition temperature and only a slight increase in the proportion of crystalline lipid during this late period in germination. The data indicate that substantial amounts of the lipid is senescing membranes are crystalline even at physiological temperature. Moreover, there is a temporal correlation between the appearance of this crystallinity and loss of membrane function, suggesting that the two may be causally related. Images PMID:16659947

McKersie, Bryan D.; Thompson, John E.

1977-01-01

243

Algal Lipids as Quantitative Paleosalinity Proxies  

NASA Astrophysics Data System (ADS)

The tropics play an important role in driving climate. However it is difficult to uncover past changes in tropical precipitation due to a lack of tree ring records and low accumulation rates of marine sediments. Hydrogen isotope ratios of algal lipids preserved in lacustrine and marine sediments have been used to qualitatively reconstruct tropical paleohydrology. Changes in the hydrologic balance are reflected in salinity and in lake water D/H ratios, which are closely tracked by lipid D/H ratios of algal biomarkers. While useful for determining past periods of "wetter" or "drier" conditions, variability in isotope fractionation in algal lipids during lipid biosynthesis can be exploited to more quantitatively determine how much wetter or drier conditions were in the past. The estuarine diatom, Thalassiosira pseudonnana, was grown in continuous cultures under controlled light, temperature, nutrient, and growth rate conditions to assess the influence of salinity (9-40 PSU) on D/H fractionation between lipids and source water. Three fatty acids, 24-methylcholesta-5,24(28)-dien-3B-ol, and phytol show decreasing fractionation between lipid and source water as salinity increases with 0.8-1.3‰ change in fractionation per salinity unit. These results compliment field-based empirical observations of dinosterol in Chesapeake Bay suspended particles that change 0.99‰ per salinity unit and lipid biomarkers from hyper-saline ponds on Christmas Island that change 0.7-1.1‰ per salinity unit. Biological pathways responsible for the inverse relationship between fractionation and salinity will be discussed.

Maloney, A.; Shinneman, A.; Hemeon, K.; Sachs, J. P.

2012-12-01

244

Genetic architecture of circulating lipid levels.  

PubMed

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, Ay?e; Amin, Najaf; Isaacs, Aaron; Jarvelin, Marjo-Riitta; Whitfield, John B; Wichmann, Heinz-Erich; Kyvik, Kirsten O H M; Rudan, Igor; Gieger, Christian; Hicks, Andrew A; Johansson, Åsa; Hottenga, Jouke-Jan; Smith, Johannes J; Wild, Sarah H; Pedersen, Nancy L; Willemsen, Gonneke; Mangino, Massimo; Hayward, Caroline; Uitterlinden, André G; Hofman, Albert; Witteman, Jacqueline; Montgomery, Grant W; Pietiläinen, Kirsi H; Rantanen, Taina; Kaprio, Jaakko; Döring, Angela; Pramstaller, Peter P; Gyllensten, Ulf; de Geus, Eco J C; Penninx, Brenda W; Wilson, James F; Rivadeneria, Fernando; Magnusson, Patrik K E; 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 J W; van Duijn, Cornelia M

2011-07-01

245

Synthesis of Lipids for Development of Multifunctional Lipid-Based Drug-Carriers  

PubMed Central

A simple approach to synthesize phospholipids to modulate drug release and track lipid-based particulate drug-carriers is described. We synthesized two ether lipids, 1 1-O-hexadecyl-2-pentadenoyl-sn-glycerol-3-phosphocholine (C31PC) and 2 1-O-hexadecyl-2-pentadenoyl-sn-glycerol-3-phosphomethanol (C31PM), and examined their ability to alter enzymatically triggered release of 6-carboxyfluorescein from liposomes incubated in TRIS buffer or fetal bovine serum solutions. Further, we demonstrated that odd-chain lipids, e.g., C31PC, could be identified in rat plasma without interference of endogenous lipids. This approach can be adapted to synthesize a variety of lipids for use in developing and optimizing multifunctional drug-carriers. PMID:21955941

Zhu, Guodong; Hamhoom, Yahya Al; Cummings, Brian S.; Arnold, Robert D.

2011-01-01

246

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

247

Elastic constants of polymer-grafted lipid membranes.  

PubMed Central

The surface expansion that is induced by the lateral pressure in the brush region of lipid membranes containing grafted polymers is deduced from the scaling and mean-field theories for the polymer brush, together with the equation of state for a lipid monolayer at the equivalence pressure with fluid lipid bilayers. Depending on the length and mole fraction of the polymer lipid, the membrane expansion can be appreciable. Direct experimental evidence for this lateral expansion comes from recent spin-label measurements with lipid membranes containing poly(ethylene glycol)-grafted lipids. The expansion in lipid area modifies the elastic constants of the polymer-grafted membranes in a way that opposes the direct elastic response of the polymer itself. Calculations as a function of polymer lipid content indicate that the net change in isothermal area expansion modulus of the membrane is negative but small, in contrast to previous predictions. A similar situation applies to the curvature elastic moduli of membranes containing short polymer lipids. For longer polymer lipids, however, the direct contribution of the polymer brush to the bending elastic constants dominates, and the increase in bending moduli with increasing polymer lipid content rapidly exceeds the basal values of the bare lipid membrane. The spontaneous (or intrinsic) curvature of the component monolayer of polymer lipid-containing membranes is calculated for the first time. The polymer brush contribution to spontaneous curvature scales quadratically with the polymer length, and at least quadratically with the mole fraction of polymer lipid. PMID:11566786

Marsh, D

2001-01-01

248

Surface features of the lipid droplet mediate perilipin 2 localization.  

PubMed

All eukaryotic organisms store excess lipid in intracellular lipid droplets. These dynamic structures are associated with and regulated by numerous proteins. Perilipin 2, an abundant protein on most lipid droplets, promotes neutral lipid accumulation in lipid droplets. However, the mechanism by which perilipin 2 binds to and remains anchored on the lipid droplet surface is unknown. Here we identify features of the lipid droplet surface that influence perilipin 2 localization. We show that perilipin 2 binding to the lipid droplet surface requires both hydrophobic and electrostatic interactions. Reagents that disrupt these interactions also decrease binding. Moreover, perilipin 2 binding does not depend on other lipid droplet-associated proteins but is influenced by the lipid composition of the surface. Perilipin 2 binds to synthetic vesicles composed of dioleoylphosphatidylcholine, a phospholipid with unsaturated acyl chains. Decreasing the temperature of the binding reaction, or introducing phospholipids with saturated acyl chains, decreases binding. We therefore demonstrate a role for surface lipids and acyl chain packing in perilipin 2 binding to lipid droplets. The ability of the lipid droplet phospholipid composition to impact protein binding may link changes in nutrient availability to lipid droplet homeostasis. PMID:25172666

Sletten, Arthur; Seline, Alison; Rudd, Andrew; Logsdon, Michelle; Listenberger, Laura L

2014-09-26

249

Electrostatic swelling of bicontinuous cubic lipid phases.  

PubMed

Lipid bicontinuous cubic phases have attracted enormous interest as bio-compatible scaffolds for use in a wide range of applications including membrane protein crystallisation, drug delivery and biosensing. One of the major bottlenecks that has hindered exploitation of these structures is an inability to create targeted highly swollen bicontinuous cubic structures with large and tunable pore sizes. In contrast, cubic structures found in vivo have periodicities approaching the micron scale. We have been able to engineer and control highly swollen bicontinuous cubic phases of spacegroup Im3m containing only lipids by (a) increasing the bilayer stiffness by adding cholesterol and (b) inducing electrostatic repulsion across the water channels by addition of anionic lipids to monoolein. By controlling the composition of the ternary mixtures we have been able to achieve lattice parameters up to 470 Å, which is 5 times that observed in pure monoolein and nearly twice the size of any lipidic cubic phase reported previously. These lattice parameters significantly exceed the predicted maximum swelling for bicontinuous cubic lipid structures, which suggest that thermal fluctuations should destroy such phases for lattice parameters larger than 300 Å. PMID:25790335

Tyler, Arwen I I; Barriga, Hanna M G; Parsons, Edward S; McCarthy, Nicola L C; Ces, Oscar; Law, Robert V; Seddon, John M; Brooks, Nicholas J

2015-04-01

250

ROLE OF THE GUT IN LIPID HOMEOSTASIS  

PubMed Central

Intestinal lipid transport plays a central role in fat homeostasis. Here we review the pathways regulating intestinal absorption and delivery of dietary and biliary lipid substrates, principally long-chain fatty acid, cholesterol, and other sterols. We discuss the regulation and functions of CD36 in fatty acid absorption, NPC1L1 in cholesterol absorption, as well as other lipid transporters including FATP4 and SRB1. We discuss the pathways of intestinal sterol efflux via ABCG5/G8 and ABCA1 as well as the role of the small intestine in high-density lipoprotein (HDL) biogenesis and reverse cholesterol transport. We review the pathways and genetic regulation of chylomicron assembly, the role of dominant restriction points such as microsomal triglyceride transfer protein and apolipoprotein B, and the role of CD36, L-FABP, and other proteins in formation of the prechylomicron complex. We will summarize current concepts of regulated lipoprotein secretion (including HDL and chylomicron pathways) and include lessons learned from families with genetic mutations in dominant pathways (i.e., abetalipoproteinemia, chylomicron retention disease, and familial hypobetalipoproteinemia). Finally, we will provide an integrative view of intestinal lipid homeostasis through recent findings on the role of lipid flux and fatty acid signaling via diverse receptor pathways in regulating absorption and production of satiety factors. PMID:22811425

Abumrad, Nada A.; Davidson, Nicholas O.

2013-01-01

251

Alzheimer A? peptide interactions with lipid membranes  

PubMed Central

Fibrillar aggregates of misfolded amyloid proteins are involved in a variety of diseases such as Alzheimer disease (AD), type 2 diabetes, Parkinson, Huntington and prion-related diseases. In the case of AD amyloid ? (A?) peptides, the toxicity of amyloid oligomers and larger fibrillar aggregates is related to perturbing the biological function of the adjacent cellular membrane. We used atomistic molecular dynamics (MD) simulations of A?9–40 fibrillar oligomers modeled as protofilament segments, including lipid bilayers and explicit water molecules, to probe the first steps in the mechanism of A?-membrane interactions. Our study identified the electrostatic interaction between charged peptide residues and the lipid headgroups as the principal driving force that can modulate the further penetration of the C-termini of amyloid fibrils or fibrillar oligomers into the hydrophobic region of lipid membranes. These findings advance our understanding of the detailed molecular mechanisms and the effects related to A?-membrane interactions, and suggest a polymorphic structural character of amyloid ion channels embedded in lipid bilayers. While inter-peptide hydrogen bonds leading to the formation of ?-strands may still play a stabilizing role in amyloid channel structures, these may also present a significant helical content in peptide regions (e.g., termini) that are subject to direct interactions with lipids rather than with neighboring A? peptides. PMID:22874669

Tofoleanu, Florentina; Buchete, Nicolae-Viorel

2012-01-01

252

Circadian regulators of intestinal lipid absorption.  

PubMed

Among all the metabolites present in the plasma, lipids, mainly triacylglycerol and diacylglycerol, show extensive circadian rhythms. These lipids are transported in the plasma as part of lipoproteins. Lipoproteins are synthesized primarily in the liver and intestine and their production exhibits circadian rhythmicity. Studies have shown that various proteins involved in lipid absorption and lipoprotein biosynthesis show circadian expression. Further, intestinal epithelial cells express circadian clock genes and these genes might control circadian expression of different proteins involved in intestinal lipid absorption. Intestinal circadian clock genes are synchronized by signals emanating from the suprachiasmatic nuclei that constitute a master clock and from signals coming from other environmental factors, such as food availability. Disruptions in central clock, as happens due to disruptions in the sleep/wake cycle, affect intestinal function. Similarly, irregularities in temporal food intake affect intestinal function. These changes predispose individuals to various metabolic disorders, such as metabolic syndrome, obesity, diabetes, and atherosclerosis. Here, we summarize how circadian rhythms regulate microsomal triglyceride transfer protein, apoAIV, and nocturnin to affect diurnal regulation of lipid absorption. PMID:25057097

Hussain, M Mahmood; Pan, Xiaoyue

2015-04-01

253

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

Wüstner, Daniel; Sklenar, Heinz

2014-01-01

254

Intravenous Lipids for Preterm Infants: A Review  

PubMed Central

Extremely low birth weight infants (ELBW) are born at a time when the fetus is undergoing rapid intrauterine brain and body growth. Continuation of this growth in the first several weeks postnatally during the time these infants are on ventilator support and receiving critical care is often a challenge. These infants are usually highly stressed and at risk for catabolism. Parenteral nutrition is needed in these infants because most cannot meet the majority of their nutritional needs using the enteral route. Despite adoption of a more aggressive approach with amino acid infusions, there still appears to be a reluctance to use early intravenous lipids. This is based on several dogmas that suggest that lipid infusions may be associated with the development or exacerbation of lung disease, displace bilirubin from albumin, exacerbate sepsis, and cause CNS injury and thrombocytopena. Several recent reviews have focused on intravenous nutrition for premature neonate, but very little exists that provides a comprehensive review of intravenous lipid for very low birth and other critically ill neonates. Here, we would like to provide a brief basic overview, of lipid biochemistry and metabolism of lipids, especially as they pertain to the preterm infant, discuss the origin of some of the current clinical practices, and provide a review of the literature, that can be used as a basis for revising clinical care, and provide some clarity in this controversial area, where clinical care is often based more on tradition and dogma than science. PMID:25698888

Salama, Ghassan SA; Kaabneh, Mahmmoud AF; Almasaeed, Mai N; Alquran, Mohammad IA

2015-01-01

255

Hypothyroidism modifies lipid composition of polymorphonuclear leukocytes.  

PubMed

Thyroid hormones are important regulators of lipid metabolism. Polymorphonuclear leukocytes (PMN) are essential components of innate immune response. Our goal was to determine whether hypothyroidism affects lipid metabolism in PMN cells. Wistar rats were made hypothyroid by administrating 0.1 g/L 6-propyl-2-thiouracil (PTU) in drinking water during 30 days. Triacylglycerides (TG), cholesterol and phospholipids were determined in PMN and serum by conventional methods. The mRNA expression of LDL receptor (LDL-R), 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCoAR), sterol regulatory element binding protein 2 (SREBP-2), and diacylglycerol acyltransferase 2 (DGAT-2) were quantified by Real-Time PCR. Cellular neutral lipids were identified by Nile red staining. We found hypothyroidism decreases serum TG whereas it increases them in PMN. This result agrees with those observed in Nile red preparations, however DAGT-2 expression was not modified. Cholesterol synthesizing enzyme HMGCoAR mRNA and protein was reduced in PMN of hypothyroid rats. As expected, cholesterol content decreased in the cells although it increased in serum. Hypothyroidism also reduced relative contents of palmitic, stearic, and arachidonic acids, whereas increased the myristic, linoleic acids, and the unsaturation index in PMN. Thus, hypothyroidism modifies PMN lipid composition. These findings would emphasize the importance of new research to elucidate lipid-induced alterations in specific function(s) of PMN. PMID:22613972

Coria, Mariela J; Carmona Viglianco, Yamila V; Marra, Carlos A; Gomez-Mejiba, Sandra E; Ramirez, Dario C; Anzulovich, Ana C; Gimenez, Maria S

2012-01-01

256

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

257

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

258

Freely drawn single lipid nanotube patterns.  

PubMed

LNTs are unique 3D structures made only of safe and abundant biomaterials by self-assembly. The current bottleneck for developing applications using LNTs is the lack of an easy technique to pattern them on substrates. We report a method to free-draw single lipid nanotube (LNT) patterns in any shape on surfaces with 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) that takes an inverted hexagonal (HII) phase. We used pre-self-assembled LNTs or HII lipid blocks as a lipid reservoir from which new LNTs were pulled by applying a point load with a micromanipulator. The extreme simplicity of our technique originates from the fundamental nature of DOPE lipids that prefer a HII phase, while all the conventional approaches use PC lipids that form a lamellar phase. By adjusting the surface properties with polyelectrolyte multilayers, the created single LNT objects are able to remain adhered to the surface for over a week. Importantly, it could be shown that two vesicles loaded with caged fluorescent molecules were able to fuse well with a LNT, enabling diffusive transport of uncaged fluorescent molecules from one vesicle to the other. PMID:25626419

Sugihara, Kaori; Rustom, Amin; Spatz, Joachim P

2015-02-25

259

Lipid binding proteins from parasitic platyhelminthes  

PubMed Central

Two main families of lipid binding proteins have been identified in parasitic Platyhelminthes: hydrophobic ligand binding proteins (HLBPs) and fatty acid binding proteins (FABPs). Members of the former family of proteins are specific to the Cestoda class, while FABPs are conserved across a wide range of animal species. Because Platyhelminthes are unable to synthesize their own lipids, these lipid-binding proteins are important molecules in these organisms. HLBPs are a high molecular mass complex of proteins and lipids. They are composed of subunits of low molecular mass proteins and a wide array of lipid molecules ranging from CoA esters to cholesterol. These proteins are excretory-secretory molecules and are key serological tools for diagnosis of diseases caused by cestodes. FABPs are mainly intracellular proteins of low molecular weight. They are also vaccine candidates. Despite that the knowledge of their function is scarce, the differences in their molecular organization, ligand preferences, intra/extracellular localization, evolution, and phylogenetic distribution, suggest that platyhelminths HLBPs and FABPs should play different functions. FABPs might be involved in the removal of fatty acids from the inner surface of the cell membrane and in their subsequent targeting to specific cellular destinations. In contrast, HLBPs might be involved in fatty acid uptake from the host environment. PMID:22988444

Alvite, Gabriela; Esteves, Adriana

2012-01-01

260

Integral hair lipid in human hair follicle.  

PubMed

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, ceramide in decreasing order. Minor constituents of IHL are cholesterol, cholesterol sulfate and cholesterol oleate. Cuticle or cortical cell surface in hair are abundant in fatty acids unlike the keratinized area of epidermis or sebaceous gland, and about 30-40% of such fatty acids are composed of 18-methyl-eicosanoic acid which is known to be bound to proteins by ester or thioester bond. Various factors including moisture, solvent, oxidative damage during bleaching or permanent waving affect IHL. Photochemical changes also can occur in IHL as well as in hair protein and hair pigment. Lipid metabolism is thought to play an essential role in lipid envelope of hair, but also involvement in hair development and function. PMID:21906914

Lee, Won-Soo

2011-12-01

261

In vitro systems for Atg8 lipidation  

PubMed Central

Macroautophagy is a major bulk degradation pathway for cytoplasmic material in eukaryotic cells. During macroautophagy, double membrane-bound organelles called autophagosomes are formed in a de novo manner. In the course of their formation autophagosomes capture cytoplasmic material, which is subsequently degraded upon fusion with the lysosomal system in complex eukaryotes or the vacuole in yeast. Several proteins are required for autophagosome formation. Among these are the components of two ubiquitin-like conjugation reactions that collectively mediate the conjugation of the ubiquitin-like Atg12 to the Atg5 protein and of the ubiquitin-like protein Atg8 to the headgroup of the membrane lipid phosphatidylethanolamine. The lipidated form of Atg8 is membrane-bound and marks the growing autophagosomal membrane as well as the completed autophagosome. Here we describe assays for the in vitro reconstitution of the Atg8 lipidation reaction using recombinantly expressed and purified proteins derived from Saccharomycescerevisiae in combination with small and giant unilamellar vesicles. The assays enable the study of the biochemical mechanisms of action of the Atg8 lipidation machinery and to analyze the impact of mutations and post-translational modifications of the conjugation machinery on Atg8 lipidation. PMID:25461810

Zens, Bettina; Sawa-Makarska, Justyna; Martens, Sascha

2015-01-01

262

Lipid exchange and transfer on nanoparticle supported lipid bilayers: effect of defects, ionic strength, and size.  

PubMed

Lipid exchange/transfer has been compared for zwitterionic 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-dimyristoyl-d54-sn-glycero-3-phosphocholine (DMPC) small unilamellar vesicles (SUVs) and for the same lipids on silica (SiO2) nanoparticle supported lipid bilayers (NP-SLBs) as a function of ionic strength, temperature, temperature cycling, and NP size, above the main gel-to-liquid crystal phase transition temperature, Tm, using d- and h-DMPC and DPPC. Increasing ionic strength decreases the exchange kinetics for the SUVs, but more so for the NP-SLBs, due to better packing of the lipids and increased attraction between the lipid and support. When the NP-SLBs (or SUVs) are cycled above and below Tm, the exchange rate increases compared with exchange at the same temperature without cycling, for similar total times, suggesting that defects provide sites for more facile removal and thus exchange of lipids. Defects can occur: (i) at the phase boundaries between coexisting gel and fluid phases at Tm; (ii) in bare regions of exposed SiO2 that form during NP-SLB formation due to mismatched surface areas of lipid and NPs; and (iii) during cycling as the result of changes in area of the lipids at Tm and mismatched thermal expansion coefficient between the lipids and SiO2 support. Exchange rates are faster for NP-SLBs prepared with the nominal amount of lipid required to form a NP-SLB compared with NP-SLBs that have been prepared with excess lipids to minimize SiO2 patches. Nanosystems prepared with equimolar mixtures of NP-SLBs composed of d-DMPC (d(DMPC)-NP-SLB) and SUVs composed of h-DMPC (h(DMPC)-SUV) show that the calorimetric transition of the "donor" h(DMPC)-SUV decreases in intensity without an initial shift in Tm, indicating that the "acceptor" d(DMPC)-NP-SLB can accommodate more lipids, through either further fusion or insertion of lipids into the distal monolayer. Exchange for d/h(DMPC)-NP-SLB is in the order 100 nm SiO2 > 45 nm SiO2 > 5 nm SiO2. PMID:25425021

Drazenovic, Jelena; Ahmed, Selver; Tuzinkiewicz, Nicole-Marie; Wunder, Stephanie L

2015-01-20

263

The Role of Lipids in VDAC Oligomerization  

PubMed Central

Evidence has accumulated that the voltage-dependent anion channel (VDAC), located on the outer membrane of mitochondria, plays a central role in apoptosis. The involvement of VDAC oligomerization in apoptosis has been suggested in various studies. However, it still remains unknown how exactly VDAC supramolecular assembly can be regulated in the membrane. This study addresses the role of lipids in this process. We investigate the effect of cardiolipin (CL) and phosphatidylglycerol (PG), anionic lipids important for mitochondria metabolism and apoptosis, on VDAC oligomerization. By applying fluorescence cross-correlation spectroscopy to VDAC reconstituted into giant unilamellar vesicles, we demonstrate that PG significantly enhances VDAC oligomerization in the membrane, whereas cardiolipin disrupts VDAC supramolecular assemblies. During apoptosis, the level of PG in mitochondria increases, whereas the CL level decreases. We suggest that the specific lipid composition of the outer mitochondrial membrane might be of crucial relevance and, thus, a potential cue for regulating the oligomeric state of VDAC. PMID:22325275

Betaneli, Viktoria; Petrov, Eugene P.; Schwille, Petra

2012-01-01

264

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

265

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

266

Nanostructure of cationic lipid-oligonucleotide complexes.  

PubMed

Complexes (lipoplexes) between cationic liposomes and single-strand oligodeoxynucleotides (ODN) are potential delivery systems for antisense therapy. The nanometer-scale morphology of these assemblies is relevant to their transfection efficiency. In this work the monocationic lipid dioleoyloxytrimethylammoniumpropane, the neutral "helper" lipid cholesterol, and an 18-mer anti-bcl2 ODN were combined at different ratios. The lipoplexes formed were characterized for the quantity of ODN bound, for the degree of lipid mixing, and for their size. The nanostructure of the system was examined by cryogenic-temperature transmission electron microscopy, augmented by small-angle x-ray scattering. Addition of ODN to cationic liposomes induced both liposome aggregation and the formation of a novel condensed lamellar phase. This phase is proposed to be stabilized by anionic single-strand ODN molecules intercalated between cationic bilayers. The proportion of cholesterol present apparently did not affect the nature of lipoplex microstructure, but changed the interlamellar spacing. PMID:15240493

Weisman, Sarah; Hirsch-Lerner, Danielle; Barenholz, Yechezkel; Talmon, Yeshayahu

2004-07-01

267

Dengue virus induced autophagy regulates lipid metabolism  

PubMed Central

Summary Autophagy influences numerous cellular processes, including innate and adaptive immunity against intracellular pathogens. However, some viruses, including dengue virus (DENV), usurp autophagy to enhance their replication. The mechanism for a positive role of autophagy in DENV infection is unclear. We present data that DENV induction of autophagy regulates cellular lipid metabolism. DENV infection leads to an autophagy-dependent processing of lipid droplets and triglycerides to release free fatty acids. This results in an increase in cellular ?-oxidation, which generates ATP. These processes are required for efficient DENV replication. Importantly, exogenous fatty acids can supplant the requirement of autophagy in DENV replication. These results define a role for autophagy in DENV infection and provide a mechanism by which viruses can alter cellular lipid metabolism to promote their replication. PMID:21075353

Heaton, Nicholas S.; Randall, Glenn

2010-01-01

268

Peptide-Lipid Interactions: Experiments and Applications  

PubMed Central

The interactions between peptides and lipids are of fundamental importance in the functioning of numerous membrane-mediated cellular processes including antimicrobial peptide action, hormone-receptor interactions, drug bioavailability across the blood-brain barrier and viral fusion processes. Moreover, a major goal of modern biotechnology is obtaining new potent pharmaceutical agents whose biological action is dependent on the binding of peptides to lipid-bilayers. Several issues need to be addressed such as secondary structure, orientation, oligomerization and localization inside the membrane. At the same time, the structural effects which the peptides cause on the lipid bilayer are important for the interactions and need to be elucidated. The structural characterization of membrane active peptides in membranes is a harsh experimental challenge. It is in fact accepted that no single experimental technique can give a complete structural picture of the interaction, but rather a combination of different techniques is necessary. PMID:24036440

Galdiero, Stefania; Falanga, Annarita; Cantisani, Marco; Vitiello, Mariateresa; Morelli, Giancarlo; Galdiero, Massimiliano

2013-01-01

269

mitochondrial pathway for biosynthesis of lipid mediators  

PubMed Central

The central role of mitochondria in metabolic pathways and in cell death mechanisms requires sophisticated signaling systems. Essential in this signaling process is an array of lipid mediators derived from polyunsaturated fatty acids. However, the molecular machinery for the production of oxygenated polyunsaturated fatty acids is localized in the cytosol and their biosynthesis has not been identified in mitochondria. Here we report that a range of diversified polyunsaturated molecular species derived from a mitochondria-specific phospholipid, cardiolipin, are oxidized by the intermembrane space hemoprotein, cytochrome c. We show that an assortment of oxygenated cardiolipin species undergoes phospholipase A2-catalyzed hydrolysis thus generating multiple oxygenated fatty acids, including well known lipid mediators. This represents a new biosynthetic pathway for lipid mediators. We demonstrate that this pathway including oxidation of polyunsaturated cardiolipins and accumulation of their hydrolysis products – oxygenated linoleic, arachidonic acids and monolyso-cardiolipins – is activated in vivo after acute tissue injury. PMID:24848241

Tyurina, Yulia Y.; Poloyac, Samuel M.; Tyurin, Vladimir A.; Kapralov, Alexander A.; Jiang, Jianfei; Anthonymuthu, Tamil Selvan; Kapralova, Valentina I.; Vikulina, Anna S.; Jung, Mi-Yeon; Epperly, Michael W.; Mohammadyani, Dariush; Klein-Seetharaman, Judith; Jackson, Travis C.; Kochanek, Patrick M.; Pitt, Bruce R.; Greenberger, Joel S.; Vladimirov, Yury A.; Bay?r, Hülya; Kagan, Valerian E.

2014-01-01

270

Membrane protein dynamics: limited lipid control  

PubMed Central

Correlation of lipid disorder with membrane protein dynamics has been studied with infrared spectroscopy, by combining data characterizing lipid phase, protein structure and, via hydrogen-deuterium (H/D) exchange, protein dynamics. The key element was a new measuring scheme, by which the combined effects of time and temperature on the H/D exchange could be separated. Cyanobacterial and plant thylakoid membranes, mammalian mitochondria membranes, and for comparison, lysozyme were investigated. In dissolved lysozyme, as a function of temperature, H/D exchange involved only reversible movements (the secondary structure did not change considerably); heat-denaturing was a separate event at much higher temperature. Around the low-temperature functioning limit of the biomembranes, lipids affected protein dynamics since changes in fatty acyl chain disorders and H/D exchange exhibited certain correlation. H/D exchange remained low in all membranes over physiological temperatures. Around the high-temperature functioning limit of the membranes, the exchange rates became higher. When temperature was further increased, H/D exchange rates went over a maximum and afterwards decreased (due to full H/D exchange and/or protein denaturing). Maximal H/D exchange rate temperatures correlated neither with the disorder nor with the unsaturation of lipids. In membrane proteins, in contrast to lysozyme, the onsets of sizable H/D exchange rates were the onsets of irreversible denaturing as well. Seemingly, at temperatures where protein self-dynamics allows large-scale H/D exchange, lipid-protein coupling is so weak that proteins prefer aggregating to limit the exposure of their hydrophobic surface regions to water. In all membranes studied, dynamics seemed to be governed by lipids around the low-temperature limit, and by proteins around the high-temperature limit of membrane functionality. PACS codes: 87.14.ep, 87.14.cc, 87.16.D PMID:19351429

Szalontai, Balázs

2009-01-01

271

Fluorescence-based evaluation of the partitioning of lipids and lipidated peptides into liquid-ordered lipid microdomains: a model for molecular partitioning into "lipid rafts".  

PubMed Central

A fluorescence-quenching assay is described that can directly monitor the relative extents of partitioning of different but structurally homologous fluorescent molecules into liquid-ordered (l(o)) domains in lipid vesicles exhibiting liquid-ordered/liquid-disordered (l(o)/l(d)) phase coexistence. Applying this assay to a series of bimane-labeled diacyl phospholipid probes in cholesterol-containing ternary lipid mixtures exhibiting l(o)/l(d) phase separation, we demonstrate that partitioning into l(o)-phase domains is negligible for diunsaturated species and greatest for long-chain disaturated species. These conclusions agree well with those derived from previous studies of the association of lipids and lipid-anchored molecules with l(o)-phase domains, using methods based on the isolation of a detergent-insoluble fraction from model or biological membranes at low temperatures. However, we also find that monounsaturated and shorter-chain saturated species partition into l(o) phases with significant, albeit modest affinities, and that the level of partitioning of these latter species into l(o)-phase domains is significantly underestimated (relative to that of their long-chain saturated counterparts) by the criterion of low-temperature detergent insolubility. Finally, applying the fluorescence-quenching method to a family of lipid-modified peptides, we demonstrate that the S-palmitoyl/S-isoprenyl dual-lipidation motif found in proteins such as H- and N-ras and yeast Ste18p does not promote significant association with l(o) domains in l(o)/l(d)-phase-separated bilayers. PMID:10920023

Wang, T Y; Leventis, R; Silvius, J R

2000-01-01

272

Silica-lipid hybrid microcapsules: influence of lipid and emulsifier type on in vitro performance.  

PubMed

This study reports on the physicochemical characterisation and in vitro investigations of macro-porous silica-lipid hybrid (SLH) microcapsules when formulated using various lipids: long-chain triglycerides (LCT), medium-chain triglycerides (MCT), medium-chain mono-, diglycerides (MCMDG); and emulsifiers: anionic lecithin and cationic oleylamine. For the lipophilic compound coumarin 102 (logP=4.09), a complete and immediate in vitro release was attained for the SLH microcapsules under simulated intestinal sink conditions. The in vitro digestion study of various types of SLH microcapsules demonstrates: (i) reduced variability and enhanced lipid digestibility for the MCMDG-based microcapsules (i.e. 90-100% lipolysis) in comparison with an equivalent lipid solution and emulsion (50-90% lipolysis); and (ii) more controllable digestion kinetics for the LCT-based microcapsules which produce a lipolysis rate higher than that of a lipid solution but lower than that of a lipid emulsion. The drug phase partition results show approximately 5- to 17-fold increase in the drug solubilisation degree resulting from the digestion of MCT and MCMDG-based microcapsules (116 ?g/mL), and LCT-based microcapsules (416 ?g/mL) in comparison with the blank micellar medium (24 ?g/mL). In conclusion, the SLH microcapsules could be tailored to manipulate the digestion patterns of both medium- and long-chain lipids in order to maximise the drug solubilisation capacity. PMID:21371543

Lim, Li Hui; Tan, Angel; Simovic, Spomenka; Prestidge, Clive A

2011-05-16

273

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

274

Lipid Anti-Lipid Antibody Responses Correlate with Disease Activity in Systemic Lupus Erythematosus  

PubMed Central

Systemic Lupus Erythematosus (SLE) is a chronic autoimmune disorder characterized by broad clinical manifestations including cardiovascular and renal complications with periodic disease flares and significant morbidity and mortality. One of the main contributing factors to the pathology of SLE is the accumulation and impaired clearance of immune complexes of which the principle components are host auto-antigens and antibodies. The contribution of host lipids to the formation of these autoimmune complexes remains poorly defined. The aim of the present study was to identify and analyze candidate lipid autoantigens and their corresponding anti–lipid antibody responses in a well-defined SLE patient cohort using a combination of immunological and biophysical techniques. Disease monitoring in the SLE cohort was undertaken with serial British Isles Lupus Assessment Group (BILAG) scoring. Correlations between specific lipid/anti-lipid responses were investigated as disease activity developed from active flares to quiescent during a follow up period. We report a significant negative correlation between anti-lipid antibodies for 24S-hydroxycholesterol, cardiolipin and phosphatidylserine with SLE disease activity. Taken together, these data suggest that lipid autoantigens represent a new family of biomarkers that can be employed to monitor disease activity plus the efficacy of therapeutic intervention in SLE. PMID:23409013

Jovanovi?, Vojislav; Abdul Aziz, Nurhuda; Lim, Yan Ting; Ng Ai Poh, Amanda; Jin Hui Chan, Sherlynn; Ho Xin Pei, Eliza; Lew, Fei Chuin; Shui, Guanghou; Jenner, Andrew M.; Bowen, Li; McKinney, Eoin F.; Lyons, Paul A.; Kemeny, Michael D.; Smith, Kenneth G. C.; Wenk, Markus R.; MacAry, Paul A.

2013-01-01

275

A comparative study: the impact of different lipid extraction methods on current microalgal lipid research.  

PubMed

Microalgae cells have the potential to rapidly accumulate lipids, such as triacylglycerides that contain fatty acids important for high value fatty acids (e.g., EPA and DHA) and/or biodiesel production. However, lipid extraction methods for microalgae cells are not well established, and there is currently no standard extraction method for the determination of the fatty acid content of microalgae. This has caused a few problems in microlagal biofuel research due to the bias derived from different extraction methods. Therefore, this study used several extraction methods for fatty acid analysis on marine microalga Tetraselmis sp. M8, aiming to assess the potential impact of different extractions on current microalgal lipid research. These methods included classical Bligh & Dyer lipid extraction, two other chemical extractions using different solvents and sonication, direct saponification and supercritical CO? extraction. Soxhlet-based extraction was used to weigh out the importance of solvent polarity in the algal oil extraction. Coupled with GC/MS, a Thermogravimetric Analyser was used to improve the quantification of microalgal lipid extractions. Among these extractions, significant differences were observed in both, extract yield and fatty acid composition. The supercritical extraction technique stood out most for effective extraction of microalgal lipids, especially for long chain unsaturated fatty acids. The results highlight the necessity for comparative analyses of microalgae fatty acids and careful choice and validation of analytical methodology in microalgal lipid research. PMID:24456581

Li, Yan; Ghasemi Naghdi, Forough; Garg, Sourabh; Adarme-Vega, Tania Catalina; Thurecht, Kristofer J; Ghafor, Wael Abdul; Tannock, Simon; Schenk, Peer M

2014-01-01

276

A comparative study: the impact of different lipid extraction methods on current microalgal lipid research  

PubMed Central

Microalgae cells have the potential to rapidly accumulate lipids, such as triacylglycerides that contain fatty acids important for high value fatty acids (e.g., EPA and DHA) and/or biodiesel production. However, lipid extraction methods for microalgae cells are not well established, and there is currently no standard extraction method for the determination of the fatty acid content of microalgae. This has caused a few problems in microlagal biofuel research due to the bias derived from different extraction methods. Therefore, this study used several extraction methods for fatty acid analysis on marine microalga Tetraselmis sp. M8, aiming to assess the potential impact of different extractions on current microalgal lipid research. These methods included classical Bligh & Dyer lipid extraction, two other chemical extractions using different solvents and sonication, direct saponification and supercritical CO2 extraction. Soxhlet-based extraction was used to weigh out the importance of solvent polarity in the algal oil extraction. Coupled with GC/MS, a Thermogravimetric Analyser was used to improve the quantification of microalgal lipid extractions. Among these extractions, significant differences were observed in both, extract yield and fatty acid composition. The supercritical extraction technique stood out most for effective extraction of microalgal lipids, especially for long chain unsaturated fatty acids. The results highlight the necessity for comparative analyses of microalgae fatty acids and careful choice and validation of analytical methodology in microalgal lipid research. PMID:24456581

2014-01-01

277

Initiation of lipid peroxidation in biological systems.  

PubMed

The direct oxidation of PUFA by triplet oxygen is spin forbidden. The data reviewed indicate that lipid peroxidation is initiated by nonenzymatic and enzymatic reactions. One of the first steps in the initiation of lipid peroxidation in animal tissues is by the generation of a superoxide radical (see Figure 16), or its protonated molecule, the perhydroxyl radical. The latter could directly initiate PUFA peroxidation. Hydrogen peroxide which is produced by superoxide dismutation or by direct enzymatic production (amine oxidase, glucose oxidase, etc.) has a very crucial role in the initiation of lipid peroxidation. Hydrogen peroxide reduction by reduced transition metal generates hydroxyl radicals which oxidize every biological molecule. Hydrogen peroxide also activates myoglobin, hemoglobin, and other heme proteins to a compound containing iron at a higher oxidation state, Fe(IV) or Fe(V), which initiates lipid peroxidation even on membranes. Complexed iron could also be activated by O2- or by H2O2 to ferryl iron compound, which is supposed to initiate PUFA peroxidation. The presence of hydrogen peroxide, especially hydroperoxides, activates enzymes such as cyclooxygenase and lipoxygenase. These enzymes produce hydroperoxides and other physiological active compounds known as eicosanoids. Lipid peroxidation could also be initiated by other free radicals. The control of superoxide and perhydroxyl radical is done by SOD (a) (see Figure 16). Hydrogen peroxide is controlled in tissues by glutathione-peroxidase, which also affects the level of hydroperoxides (b). Hydrogen peroxide is decomposed also by catalase (b). Caeruloplasmin in extracellular fluids prevents the formation of free reduced iron ions which could decompose hydrogen peroxide to hydroxyl radical (c). Hydroxyl radical attacks on target lipid molecules could be prevented by hydroxyl radical scavengers, such as mannitol, glucose, and formate (d). Reduced compounds and antioxidants (ascorbic acid, alpha-tocopherol, polyphenols, etc.) (e) prevent initiation of lipid peroxidation by activated heme proteins, ferryl ion, and cyclo- and lipoxygenase. In addition, cyclooxygenase is inhibited by aspirin and nonsteroid drugs, such as indomethacin (f). The classical soybean lipoxygenase inhibitors are antioxidants, such as nordihydroguaiaretic acid (NDGA) and others, and the substrate analog 5,8,11,14 eicosatetraynoic acid (ETYA), which also inhibit cyclooxygenase (g). In food, lipoxygenase is inhibited by blanching. Initiation of lipid peroxidation was derived also by free radicals, such as NO2. or CCl3OO. This process could be controlled by antioxidants (e).(ABSTRACT TRUNCATED AT 400 WORDS) PMID:3304843

Kanner, J; German, J B; Kinsella, J E

1987-01-01

278

Lipid bilayers: clusters, domains and phases.  

PubMed

In the present chapter we discuss the complex mixing behaviour of plasma membrane lipids. To do so, we first introduce the plasma membrane and membrane mixtures often used to model its complexity. We then discuss the nature of lipid phase behaviour in bilayers and the distinction between these phases and other manifestations of non-random mixing found in one-phase mixtures, such as clusters, micelles and microemulsions. Finally, we demonstrate the applicability of Gibbs phase diagrams to the study of increasingly complex model membrane systems, with a focus on phase coexistence, morphology and their implications for the cell plasma membrane. PMID:25658342

Ackerman, David G; Feigenson, Gerald W

2015-01-01

279

Rupture of lipid vesicles near solid surfaces  

NASA Astrophysics Data System (ADS)

The behavior of lipid vesicles near solid surfaces, despite its scientific and technological significance, is poorly understood. By simultaneously taking into account (i) the dynamics of spontaneous pore opening and closing in surface bound vesicles; (ii) their volume loss via leakage through the pores; (iii) and the propagation of their contact line, we have developed a simple model that can fully describe the detailed mechanism of and provide the necessary conditions for the rupture of vesicles and the subsequent formation of supported lipid bilayers. The predictions of the model are in qualitative agreement with many of the experimental observations.

Takáts-Nyeste, Annamária; Derényi, Imre

2014-11-01

280

Density dependent friction of lipid monolayers.  

PubMed

We measure frictional properties of liquid-expanded and liquid-condensed phases of lipid Langmuir-Blodgett monolayers by interfacial force microscopy. We find that over a reasonably broad surface-density range, the friction shear strength of the lipid monolayer film is proportional to the surface area (42-74 A2/molecule) occupied by each molecule. The increase in frictional force (i.e., friction shear strength with molecular area can be attributed to the increased conformational freedom and the resulting increase in the number of available modes for energy dissipation. PMID:17655211

Goertz, M P; Stottrup, B L; Houston, J E; Zhu, X-Y

2007-12-13

281

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

282

Lipid Bilayers: Clusters, Domains and Phases  

PubMed Central

In this chapter we discuss the complex mixing behavior of plasma membrane lipids. To do so, we first introduce the plasma membrane and membrane mixtures often used to model its complexity. We then discuss the nature of lipid phase behavior in bilayers and the distinction between these phases and other manifestations of nonrandom mixing found in one-phase mixtures, such as clusters, micelles, and microemulsions. Finally, we demonstrate the applicability of Gibbs phase diagrams to the study of increasingly complex model membrane systems, with a focus on phase coexistence, morphology and their implications for the cell plasma membrane. PMID:25658342

Ackerman, David G.; Feigenson, Gerald W.

2015-01-01

283

Salt modulates the stability and lipid binding affinity of the adipocyte lipid-binding proteins  

NASA Technical Reports Server (NTRS)

Adipocyte lipid-binding protein (ALBP or aP2) is an intracellular fatty acid-binding protein that is found in adipocytes and macrophages and binds a large variety of intracellular lipids with high affinity. Although intracellular lipids are frequently charged, biochemical studies of lipid-binding proteins and their interactions often focus most heavily on the hydrophobic aspects of these proteins and their interactions. In this study, we have characterized the effects of KCl on the stability and lipid binding properties of ALBP. We find that added salt dramatically stabilizes ALBP, increasing its Delta G of unfolding by 3-5 kcal/mol. At 37 degrees C salt can more than double the stability of the protein. At the same time, salt inhibits the binding of the fluorescent lipid 1-anilinonaphthalene-8-sulfonate (ANS) to the protein and induces direct displacement of the lipid from the protein. Thermodynamic linkage analysis of the salt inhibition of ANS binding shows a nearly 1:1 reciprocal linkage: i.e. one ion is released from ALBP when ANS binds, and vice versa. Kinetic experiments show that salt reduces the rate of association between ANS and ALBP while simultaneously increasing the dissociation rate of ANS from the protein. We depict and discuss the thermodynamic linkages among stability, lipid binding, and salt effects for ALBP, including the use of these linkages to calculate the affinity of ANS for the denatured state of ALBP and its dependence on salt concentration. We also discuss the potential molecular origins and potential intracellular consequences of the demonstrated salt linkages to stability and lipid binding in ALBP.

Schoeffler, Allyn J.; Ruiz, Carmen R.; Joubert, Allison M.; Yang, Xuemei; LiCata, Vince J.

2003-01-01

284

Complex roles of hybrid lipids in the composition, order, and size of lipid membrane domains.  

PubMed

Hybrid lipids (HL) are phospholipids with one saturated chain and one unsaturated chain. HL are hypothesized to act as linactants (i.e., 2D surfactants) in cell membranes, reducing line tension and creating nanoscopic lipid domains. Here we compare three hybrid lipids of different chain unsaturation (16:0-18:1PC (POPC), 16:0-18:2PC (PLPC), and 16:0-20:4PC (PAPC)) in their abilities to alter the composition, line tension, order, and compactness of lipid domains. We found that the liquid-ordered (Lo) and liquid-disordered (Ld) lipid domains in PAPC/di18:0PC(DSPC)/cholesterol and PLPC/DSPC/cholesterol mixtures are micrometer-sized, and only the POPC/DSPC/cholesterol system has nanoscopic domains. The results indicate that some HLs with polyunsaturated chains are not linactants, and the monounsaturated POPC displays both properties of weak linactants and "Ld-phase" lipids such as di18:1PC (DOPC). The obtained phase boundaries from giant unilamellar vesicles (GUV) show that both POPC and PLPC partition well in the Lo phases. Our MD simulations reveal that these hybrid lipids decrease the order and compactness of Lo domains. Thus, hybrid lipids distinguish themselves from other lipid groups in this combined "partitioning and loosening" ability, which could explain why the Lo domains of GUVs, which often do not contain HL, are more compact than the raft domains in cell membranes. Our line tension measurement and Monte Carlo simulation both show that even the monounsaturated POPC is a weak linactant with only modest ability to occupy domain boundaries and reduce line tension. A more important property of HLs is that they can reduce physical property differences of Lo and Ld bulk domains, which also reduces line tension at domain boundaries. PMID:24456489

Hassan-Zadeh, Ebrahim; Baykal-Caglar, Eda; Alwarawrah, Mohammad; Huang, Juyang

2014-02-11

285

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

286

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

287

A Lipid E-MAP Identifies Ubx2 as a Critical Regulator of Lipid Saturation and Lipid Bilayer Stress  

PubMed Central

SUMMARY Biological membranes are complex, and the mechanisms underlying their homeostasis are incompletely understood. Here, we present a quantitative genetic interaction map (E-MAP) focused on various aspects of lipid biology, including lipid metabolism, sorting, and trafficking. This E-MAP contains ~250,000 negative and positive genetic interaction scores and identifies a molecular crosstalk of protein quality control pathways with lipid bilayer homeostasis. Ubx2p, a component of the endoplasmic-reticulum-associated degradation pathway, surfaces as a key upstream regulator of the essential fatty acid (FA) desaturase Ole1p. Loss of Ubx2p affects the transcriptional control of OLE1, resulting in impaired FA desaturation and a severe shift toward more saturated membrane lipids. Both the induction of the unfolded protein response and aberrant nuclear membrane morphologies observed in cells lacking UBX2 are suppressed by the supplementation of unsaturated FAs. Our results point toward the existence of dedicated bilayer stress responses for membrane homeostasis. PMID:23891562

Surma, Michal A.; Klose, Christian; Peng, Debby; Shales, Michael; Mrejen, Caroline; Stefanko, Adam; Braberg, Hannes; Gordon, David E.; Vorkel, Daniela; Ejsing, Christer S.; Farese, Robert; Simons, Kai; Krogan, Nevan J.; Ernst, Robert

2013-01-01

288

Fluorescopic evaluation of protein-lipid relations in cellular signalling  

Microsoft Academic Search

IntroductionCellular communication is partly mediated through the modulation of protein activity, structure and dynamics by lipids. In contrast to the biochemical aspects of lipid signalling, relatively little is known about the physical properties of the \\

E. H. W. Pap

1994-01-01

289

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

290

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

291

Importance of the hexagonal lipid phase in biological membrane organization  

PubMed Central

Domains are present in every natural membrane. They are characterized by a distinctive protein and/or lipid composition. Their size is highly variable from the nano- to the micrometer scale. The domains confer specific properties to the membrane leading to original structure and function. The determinants leading to domain organization are therefore important but remain obscure. This review presents how the ability of lipids to organize into hexagonal II or lamellar phases can promote particular local structures within membranes. Since biological membranes are composed of a mixture of lipids, each with distinctive biophysical properties, lateral and transversal sorting of lipids can promote creation of domains inside the membrane through local modulation of the lipid phase. Lipid biophysical properties have been characterized for long based on in vitro analyses using non-natural lipid molecules; their re-examinations using natural lipids might open interesting perspectives on membrane architecture occurring in vivo in various cellular and physiological contexts. PMID:24348497

Jouhet, Juliette

2013-01-01

292

Tear lipid layer and contact lens comfort: a review.  

PubMed

This review describes the impact of contact lens wear on the tear film lipid layer and how changes in the lipid layer might modulate contact lens-related discomfort. Relevant clinical, functional, and biochemical aspects of the tear film lipid layer are reviewed. Contact lens wear modulates these aspects of the lipid layer, specifically the prelens lipid layer thickness is reduced; tear evaporation rate is increased; tear breakup time is reduced; and the concentration of lipid components such as cholesterol esters, wax esters, and phospholipids varies. The full implications of these changes are unclear; however, there is some evidence that contact lens-related discomfort is associated with a thinner prelens lipid layer, increased lipid degradation, and greater secretory phospholipase A2 activity. Certain fatty acids appear to be associated with maintaining the structural stability of the tear film but their role in retarding tear evaporation and modulating contact lens-related discomfort remains to be elucidated. PMID:23584045

Rohit, Athira; Willcox, Mark; Stapleton, Fiona

2013-05-01

293

Hydrogen isotope fractionation during lipid biosynthesis by Haloarcula marismortui  

E-print Network

Hydrogen isotope fractionation during lipid biosynthesis by Haloarcula marismortui Sitindra S studied the controls on the fractionation of hydrogen isotopes during lipid biosynthesis by Haloarcula marismortui, a halophilic archaea, in pure culture experiments by varying organic substrate, the hydrogen

294

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

295

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

296

Observations on the lipids of Oochoristica agamae (Cestoda)  

Microsoft Academic Search

An investigation of the lipids ofOochoristica agamae, an anoplocephalid cestode of theAgama lizard, was undertaken. Total lipids of the parasite accounted for 8.4% of the fresh weight; neutral lipids comprised 82.98% of the total, glycolipids, 5.01%, and phospholipids, 12.03%. The major lipid classes inO. agamae include triglycerides, cholesterol, phosphatidyl choline, and phosphatidyl ethanolamine. The 16-and 18-carbon fatty acids were predominant

Siaka O. Aisien; Edward E. Ogiji

1989-01-01

297

Fatty acid composition and oxidation of lipids in Korean catfish  

Microsoft Academic Search

This study determined the lipid content and FA composition of muscle and a mixture of muscle and viscera from Korean catfish\\u000a as well as lipid oxidation and hydrolysis. Lipid content and FA compositions in Korean catfish, which were purchased every\\u000a month or two during September 1999–July 2000, were analyzed. Lipid oxidation and hydrolysis were determined as PV, thiobarbituric\\u000a acid value,

K. T. Hwang; J. E. Kim; S. G. Kang; S. T. Jung; H. J. Park; C. L. Weller

2004-01-01

298

CELL BIOLOGY: The Different Hues of Lipid Rafts  

NSDL National Science Digital Library

Access to the article is free, however registration and sign-in are required. Segregation of lipids and proteins of the plasma membrane into microdomains called lipid rafts is known to be important for many biological processes including signal transduction and pathogen invasion. In his Perspective, van Meer explains new findings (Zacharias et al.) that reveal how lipid moieties attached to proteins instruct the proteins to move into different types of lipid rafts.

Gerrit van Meer (Utrecht University; Department of Membrane Enzymology, CBLE, Institute of Biomembranes)

2002-05-03

299

Lipid extrudates as novel sustained release systems for pharmaceutical proteins  

Microsoft Academic Search

In order to develop improved lipid-based implants for proteins, the applicability of twin screw extrusion as a manufacturing strategy was investigated. Using lipid blends of low and high melting lipids, extrusion could be performed at moderate temperatures. In addition to the lipids, the implant systems contained 10% rh-interferon ?-2a (IFN-?) co-lyophilised with hydroxypropyl-?-cyclodextrin (HP-?-CD), and 10% or 20% polyethylene glycol

Sandra Schulze; Gerhard Winter

2009-01-01

300

Serum lipid levels, suicidality, and panic disorder  

Microsoft Academic Search

Although the effects of serum total cholesterol and other lipids have been implicated as a predictor of suicidal behavior in major depression, the role of cholesterol level on suicide risk for panic disorder patients is not considered as a biological marker in the literature. In this study, we examined the relationship of suicidality with serum cholesterol concentration in panic disorder.

Ömer Akil Özer; Remzi Kutani?; Mehmet Yücel Agargun; Ahmet Cemal Bal; Yavuz Selvi; Hayrettin Kara

2004-01-01

301

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

302

Stability of lipid encapsulated ferulic acid particles  

Technology Transfer Automated Retrieval System (TEKTRAN)

Encapsulation of bioactive compounds by a solid lipid matrix provides stability and a mechanism for controlled release in formulated products. Phenolic compounds exhibit antioxidant and antimicrobial activities and have applications as functional food and feed additives. Ferulic acid, a common pheno...

303

The Lipid a b liMetabolite  

E-print Network

triglyceride / phospholipid profig y p p p p · FPLC separation and purification including VLDL, LDL, and HDL ceramides total lipids fatty acid chain length and saturation n purification* nalysis* l l d t b lit system ed to HPLC separation) cussion with clients regarding materials moses@ualberta.ca) for current

MacMillan, Andrew

304

Review article Lipids in monogastric animal meat  

E-print Network

. For a long time, pig meat has been presented as a fatty meat because of the importance of subcutaneous eaten as fresh meat and without transformation, such as roasts, contain less then 2% total lipids in genetics and a better knowledge of dietary needs has allowed to improve growth performances, to increase

Paris-Sud XI, Université de

305

The organization of melatonin in lipid membranes.  

PubMed

Melatonin is a hormone that has been shown to have protective effects in several diseases that are associated with cholesterol dysregulation, including cardiovascular disease, Alzheimer's disease, and certain types of cancers. We studied the interaction of melatonin with model membranes made of dimyristoylphosphatidylcholine (DMPC) at melatonin concentrations ranging from 0.5mol% to 30mol%. From 2-dimensional X-ray diffraction measurements, we find that melatonin induces a re-ordering of the lipid membrane that is strongly dependent on the melatonin concentration. At low melatonin concentrations, we observe the presence of melatonin-enriched patches in the membrane, which are significantly thinner than the lipid bilayer. The melatonin molecules were found to align parallel to the lipid tails in these patches. At high melatonin concentrations of 30mol%, we observe a highly ordered melatonin structure that is uniform throughout the membrane, where the melatonin molecules align parallel to the bilayers and one melatonin molecule associates with 2 lipid molecules. Understanding the organization and interactions of melatonin in membranes, and how these are dependent on the concentration, may shed light into its anti-amyloidogenic, antioxidative and photoprotective properties and help develop a structural basis for these properties. PMID:25602914

Dies, Hannah; Cheung, Bonnie; Tang, Jennifer; Rheinstädter, Maikel C

2015-04-01

306

CASTOR SEED DEVELOPMENT AND STORAGE LIPID BIOSYNTHESIS  

Technology Transfer Automated Retrieval System (TEKTRAN)

To identify additional enzymatic genes or regulatory genes that may up-regulate multiple activities or entire pathways leading to the ricinoleate and TAG syntheses in castor. we have analyzed expression profiles of twelve castor lipid genes. A series of castor seeds with well-defined developmental s...

307

Lipids in innate anti-viral defense  

PubMed Central

Summary It is becoming apparent that infections by a major class of viruses, those with envelopes, can be inhibited during their entry at the step of fusion with cellular membranes. In this review, we discuss multiple innate immune mechanisms that have evolved to modify the lipid composition of cellular and viral membranes to inhibit virion fusion of enveloped viruses. PMID:24139397

Schoggins, John W.; Randall, Glenn

2013-01-01

308

Lipid abnormalities in uremia, dialysis, and transplantation  

Microsoft Academic Search

The institution of renal replacement therapy has sustained the lives of many patients with end-stage renal failure and has made it possible to study in depth the metabolic abnormalities associated with the uremic state. An important consequence of chronic uremia is the development of lipid abnormalities [1, 2], which continue to affect many patients on dialysis [1, 3, 4] and

Man Kam Chan; Zachariah Varghese; John F Moorhead

1981-01-01

309

THE RESIDUAL LIPIDS OF FISH PROTEIN CONCENTRATES  

E-print Network

concentrates (FPCs) from red hake Uro- phycis chuss; Gulf menhaden, Brevoortia pa- tronus; pout, Macrozoarces Pacific hake, Merluccius productus; northern anchovy, Engraulis mordax; Atlantic menhaden, Brevoortia temperatures and humidities, on the composition ofthe residual lipids in a hake FPC preparation. Materials

310

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

311

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

312

ORIGINAL ARTICLES Alamethicin Aggregation in Lipid Membranes  

E-print Network

by aggregates of alamethicin (Alm) were obtained in oriented stacks of model membranes of DOPC(diC18:1PC) and di curvature (Huang 1986; Andersen and Koeppe 2007). Therefore, membrane protein structure and function can measurements have indicated that the conductance behavior of the Alm channel depends on lipid properties

Nagle, John F.

313

Variation in seed lipids in Calendula germplasm  

Technology Transfer Automated Retrieval System (TEKTRAN)

Calendula officinalis (pot marigold) has considerable promise as an industrial crop, with a long history as an ornamental and medicinal plant. It is also marketed as an ingredient in cosmetics and a colorant. It produces unusual seed lipids, which can provide an additional market for commercial Ca...

314

Continuum theory of lipid bilayer electrostatics.  

PubMed

In order to address the concerns about the applicability of the continuum theory of lipid bilayers, we generalize it by including a film with uniaxial dielectric properties representing the polar head groups of the lipid molecules. As a function of the in-plane dielectric constant ?|| of this film, we encounter a sequence of different phases. For low values of ?||, transmembrane pores have aqueous cores, ions are repelled by the bilayer, and the ion permeability of the bilayer is independent of the ion radius as in the existing theory. For increasing ?||, a threshold is reached--of the order of the dielectric constant of water--beyond which ions are attracted to the lipid bilayer by generic polarization attraction, transmembrane pores collapse, and the ion permeability becomes sensitively dependent on the ion radius, results that are more consistent with experimental and numerical studies of the interaction of ions with neutral lipid bilayers. At even higher values of ?||, the ion/pore complexes are predicted to condense in the form of extended arrays. The generalized continuum theory can be tested quantitatively by studies of the ion permeability as a function of salt concentration and co-surfactant concentration. PMID:19756792

Gerami, R; Bruinsma, R F

2009-10-01

315

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...

316

Lipid encapsulated docosahexaenoic acid methyl ester  

Technology Transfer Automated Retrieval System (TEKTRAN)

Encapsulation of structurally sensitive compounds within a solid lipid matrix provides a barrier to prooxidant compounds and effectively limits the extent of oxidative degradation. Encapsulated docosahexaenoic acid (DHA) methyl ester was examined as a model compound for functional foods and feeds. S...

317

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

318

Starch-lipid composites containing cimmamaldehyde  

Technology Transfer Automated Retrieval System (TEKTRAN)

The formulation of a starch-lipid composite containing cinnamaldehyde as antimicrobial agent has been studied. Cinnamaldehyde was incorporated as an emulsion using Acetem 90-50K as a carrier and Tween 60 as the emulsifier. Oil in water emulsions were prepared by direct emulsification using a high sh...

319

Indications for lipid-lowering drugs  

Microsoft Academic Search

Summary There is overwhelming evidence from prospective studies that plasma cholesterol levels are exponentially related to coronary artery disease (CAD) risk. Inversely, the beneficial effect of lowering plasma cholesterol is convincingly established from major clinical trials. A consensus has been reached in a large number of countries on the need to lower plasma lipid levels, especially LDL-cholesterol, to delay the

J. Davignon

1991-01-01

320

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

321

Density and viscosity of lipids under pressure  

Technology Transfer Automated Retrieval System (TEKTRAN)

There is a lack of data for the viscosity of lipids under pressure. The current report is a part of the effort to fill this gap. The viscosity, density, and elastohydrodynamic film thicknesses of vegetable oil (HOSuO) were investigated. Pressure–viscosity coefficients (PVC) of HOSuO at different tem...

322

Nutrigenetics, plasma lipids, and cardiovascular risk  

Technology Transfer Automated Retrieval System (TEKTRAN)

Cardiovascular disease (CVD) results from complex interactions between genetic and environmental factors. The evidence supports that gene-environment interactions modulate plasma lipid concentrations and potentially CVD risk. Several genes (eg, apolipoprotein A-I and A-IV, apolipoprotein E, and he...

323

Are natural lipids UV-screening agents?  

Microsoft Academic Search

Isolated lipids from Deinococcus radiodurans were reconstituted at final concentrations of 1 mg\\/ml into dioleoyl phosphatidyl choline (DOPC) vesicles and assayed for the ability to protect cells of Escherichia coli against killing by UV light (254 nm). Values of D37 (UV dose required to reduce the number of surviving cells to 37% of the original number) were calculated from killing

Jeff Reeve; Lorraine H. Kligman; Robert Anderson

1990-01-01

324

Supramolecular assemblies of lipid-coated polyelectrolytes.  

PubMed

We reveal the existence of a general class of supramolecular assemblies made up of lipid-coated polyelectrolytes including the celebrated lipid-nucleic acid complexes. With the aid of high-resolution cryo-electron microscopy, we unveil the nanoscale internal organization of assemblies generated with a wide range of synthetic and biological polyelectrolytes, several of them being investigated in this context for the first time, namely, poly(styrene sulfonic acid), carboxylmethylcellulose, and filamentous actin. Using an original coarse-grained model representing lipid-coated polyelectrolytes as semiflexible tubes, we thoroughly explored the morphologies resulting from the self-assembly process as a function of tube lengths and rigidities; the computed structures are fully consistent with the experimental observations. In particular, we found a strong extension of the correlation range of the order parameter as the rigidity of the lipid-coated polyelectrolytes increases. Electrostatic interactions provide a stabilizing mechanism leading to finite-size equilibrium assemblies. These assemblies may constitute a generic route for interfacing polyelectrolytes to living cells to perform gene delivery, for instance. PMID:22428930

Tresset, Guillaume; Lansac, Yves; Romet-Lemonne, Guillaume

2012-04-01

325

Dietary lipid source and vitamin e influence on chicken meat quality and lipid oxidation stability  

E-print Network

-Kramer shear force, or water holding capacity. In conclusion, the increment in the proportion of unsaturated fatty acids increases the susceptibility to lipid oxidation in the meat. Supranutritional supplementation levels of vitamin E are more effective...

Narciso-Gaytan, Carlos

2009-05-15

326

Lipid mono- and bilayer supported on polymer films: composite polymer-lipid films on solid substrates.  

PubMed Central

We report the deposition of lipid monolayers and bilayers on polyacrylamide films deposited by radical chain reaction onto solid substrates in aqueous solutions. Polymer films of various degrees of monomer density and cross-linking are prepared. Lateral diffusion and fluorescent probe permeation measurements yield insight into the continuity of the lipid layers and show that monolayers exposed to air are much less sensitive towards polymer heterogeneities than bilayers below water, which is explained in terms of the wetting laws. The diffusion studies of lipid and lipopeptide probes yield absolute values of the frictional coefficients between the lipid layer and the polymer films and allow one to estimate the surface viscosity of the polymer film. The potential applications of supported membranes on soft thin polymer films for the preparation of biofunctionalized surfaces or biocompatible receptive surfaces for biosensors are discussed. Images FIGURE 2 FIGURE 3 FIGURE 4 PMID:7918990

Kühner, M; Tampé, R; Sackmann, E

1994-01-01

327

Atomistic Study of Lipid Membranes Containing Chloroform: Looking for a Lipid-Mediated Mechanism of Anesthesia  

PubMed Central

The molecular mechanism of general anesthesia is still a controversial issue. Direct effect by linking of anesthetics to proteins and indirect action on the lipid membrane properties are the two hypotheses in conflict. Atomistic simulations of different lipid membranes subjected to the effect of small volatile organohalogen compounds are used to explore plausible lipid-mediated mechanisms. Simulations of homogeneous membranes reveal that electrostatic potential and lateral pressure transversal profiles are affected differently by chloroform (anesthetic) and carbon tetrachloride (non-anesthetic). Simulations of structured membranes that combine ordered and disordered regions show that chloroform molecules accumulate preferentially in highly disordered lipid domains, suggesting that the combination of both lateral and transversal partitioning of chloroform in the cell membrane could be responsible of its anesthetic action. PMID:23300982

Reigada, Ramon

2013-01-01

328

DOI: 10.1002/cphc.201100680 Lipid Diffusion within Black Lipid Membranes Measured  

E-print Network

cannot be exchanged after for- mation. Since GUVs are very sensitive to osmotic pressure dif- ferences by dissolving lipids in an organic solvent and painting them over the pore. In this case, both sides

Enderlein, Jörg

329

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

330

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.

331

Lipid metabolism in regressing rat corpora lutea of pregnancy  

Microsoft Academic Search

Lipid accumulation is a hallmark of corpus luteum regression and we characterized lipids stored in rat corpora lutea of pregnancy between days 21 and 24 post coitum, the period of luteolysis. A 10-fold rise in lutein triglyceride concentrations occurred between days 2 1 and 24, which represented the major alteration in luteal lipid metabolism during luteolysis, coinciding with the ap-

J. F. Strauss; Eric Seifter; Eric L. Lien; David B. P. Goodman; R. L. Stambaugh

332

EVALUATION OF LIPID INDICES OF THE WOOD THRUSH  

Microsoft Academic Search

Many techniques for assessing lipid reserves have been used, but techniques are seldom evaluated. We evaluated five common methods (fat scoring, regression residuals of body mass vs. morphological measurements, quotients of body mass divided by mor- phological measurements, total body electrical conductivity, and water content) for assessing lipid reserves in the Wood Thrush (Hylocichla mustelina) in Rhode Island. Lipid content

COURTNEY J. CONWAY; WILLIAM R. EDDLEMAN; KENNETH L. SIMPSON

333

Lipid content of Favia fragum larvae: changes during planulation  

NASA Astrophysics Data System (ADS)

Lipid content of planula larvae of the brooding scleractinian coral Favia fragum was analysed through a monthly planulation period. The average lipid content per dry weight of F. fragum planulae was 39%, which is low compared with other scleractinian coral species. Lipid content of planulae was significantly affected by the day of release and decreased during the planulation period.

Norström, A. V.; Sandström, M.

2010-09-01

334

Extraction of Lipids from Flax Processing Waste Using Hot Ethanol  

Technology Transfer Automated Retrieval System (TEKTRAN)

The cuticle of flax stems contain lipids that provide a protective barrier to pathogens and control moisture loss. These lipids include wax esters and long chain fatty alcohols or policosanols. Cuticle fragments generated during several different fiber processing operations retain these lipid compou...

335

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

336

Docosahexaenoic acid selectively inhibits plasma membrane targeting of lipidated proteins  

Microsoft Academic Search

Membrane localization of lipidated cytosolic signaling proteins is mediated by interactions between specific lipid anchors and membranes, but little is known about the regulatory role of membrane composition in lipidated protein membrane targeting. Here, using green fluorescent protein (GFP) chimeras and quantitative fluorescence microscopy in living mouse colonocytes, we show that docosahexaenoic acid (DHA), a dietary polyunsaturated fatty acid (PUFA)

Jeongmin Seo; Rola Barhoumi; Arthur E. Johnson; Joanne R. Lupton; Robert S. Chapkin

2006-01-01

337

Domain-specific lipid distribution in macrophage plasma membranes  

Microsoft Academic Search

Lipid rafts, defined as cholesterol- and sphin- golipid-rich domains, provide specialized lipid environ- ments understood to regulate the organization and function of many plasma membrane proteins. Growing evidence of their existence, protein cargo, and regulation is based largely on the study of isolated lipid rafts; however, the con- sistency and validity of common isolation methods is con- troversial. Here, we

Katharina Gaus; Macarena Rodriguez; Kalani R. Ruberu; Ingrid Gelissen; Timothy M. Sloane; Leonard Kritharides; Wendy Jessup

2005-01-01

338

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

339

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

340

Membrane lipids: where they are and how they behave  

Microsoft Academic Search

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

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

2008-01-01

341

Adipogenesis: It is not just lipid that comprises adipose tissue  

Technology Transfer Automated Retrieval System (TEKTRAN)

Adipogenesis is the initial component of forming cells (adipocytes) capable of assimilating lipid. Lipid metabolism is a physiological process whereby lipid is stored as triacylglycerol for subsequent use when energy is required. Both processes involve cellular and molecular components. The gene reg...

342

Lipid interaction of Pseudomonas aeruginosa exotoxin A. Acid-triggered permeabilization and aggregation of lipid vesicles.  

PubMed Central

We have investigated the interaction of Pseudomonas exotoxin A with small unilamellar vesicles comprised of different phospholipids as a function of pH, toxin, and lipid concentration. We have found that this toxin induces vesicle permeabilization, as measured by the release of a fluorescent dye. Permeabilization is due to the formation of ion-conductive channels which we have directly observed in planar lipid bilayers. The toxin also produces vesicle aggregation, as indicated by an increase of the turbidity. Aggregation and permeabilization have completely different time course and extent upon toxin dose and lipid composition, thus suggesting that they are two independent events. Both time constants decrease by lowering the pH of the bulk phase or by introducing a negative lipid into the vesicles. Our results indicate that at least three steps are involved in the interaction of Pseudomonas exotoxin A with lipid vesicles. After protonation of one charged group the toxin becomes competent to bind to the surface of the vesicles. Binding is probably initiated by an electrostatic interaction because it is absolutely dependent on the presence of acidic phospholipids. Binding is a prerequisite for the subsequent insertion of the toxin into the lipid bilayer, with a special preference for phosphatidylglycerol-containing membranes, to form ionic channels. At high toxin and vesicle concentrations, bound toxin may also induce aggregation of the vesicles, particularly when phosphatidic acid is present in the lipid mixture. A quenching of the intrinsic tryptophan fluorescence of the protein, which is induced by lowering the pH of the solution, becomes more drastic in the presence of lipid vesicles. However, this further quenching takes so long that it cannot be a prerequisite to either vesicle permeabilization or aggregation. Pseudomonas exotoxin A shares many of these properties with other bacterial toxins like diphtheria and tetanus toxin. Images FIGURE 7 FIGURE 8 FIGURE 12 PMID:1723312

Menestrina, G; Pederzolli, C; Forti, S; Gambale, F

1991-01-01

343

Serum lipid levels in an Iranian adults population: Tehran lipid and glucose study  

Microsoft Academic Search

Data from 6246 participants aged 20–64 years (2339 males and 3907 females) in the cross-sectional phase of Tehran Lipid and Glucose Study (February 1999–May 2000) were used to determine distribution of serum lipid levels after 12–14 hour overnight fast. Mean total cholesterol (TC) concentration was 210 mg\\/dl. TC was significantly greater in females than males, 213 and 206 mg\\/dl, respectively

F. Azizi; M. Rahmani; A. Ghanbarian; H. Emami; P. Salehi; P. Mirmiran; N. Sarbazi

2003-01-01

344

Associations Between Acute Lipid Stress Responses and Fasting Lipid Levels 3 Years Later  

Microsoft Academic Search

The authors assessed the association between lipid responses to acute mental stress and fasting serum lipid levels 3 years later in 199 middle-aged men and women. Total cholesterol, low-density lipoprotein (LDL), and high-density lipoprotein (HDL) cholesterol increased following moderately stressful behavioral tasks. LDL cholesterol, HDL cholesterol, and total:HDL ratio measured 3 years later were predicted by acute stress responses independent

Andrew Steptoe; Lena Brydon

2005-01-01

345

Serum lipids and lipid peroxidation pattern in industrial and rural workers in India  

Microsoft Academic Search

In order to study the impact of industrial pollutants or toxicants in free radical generation and age-associated cardiovascular\\u000a diseases, serum cholesterol, high density lipoprotein (HDL)-cholesterol, lipid peroxide levels, uric acid and blood pressure\\u000a were studied in 67 male urban industrial and 85 male rural workers. In industrial workers, the higher levels of cholesterol,\\u000a lipid peroxides and uric acid are observed

K. K. Reddy; G. Bulliyya; T. Rama Chandraiah; K. S. Kumari; P. Reddanna; K. Thyagaraju

1991-01-01

346

Quercetin induces hepatic lipid omega-oxidation and lowers serum lipid levels in mice.  

PubMed

Elevated circulating lipid levels are known risk factors for cardiovascular diseases (CVD). In order to examine the effects of quercetin on lipid metabolism, mice received a mild-high-fat diet without (control) or with supplementation of 0.33% (w/w) quercetin for 12 weeks. Gas chromatography and (1)H nuclear magnetic resonance were used to quantitatively measure serum lipid profiles. Whole genome microarray analysis of liver tissue was used to identify possible mechanisms underlying altered circulating lipid levels. Body weight, energy intake and hepatic lipid accumulation did not differ significantly between the quercetin and the control group. In serum of quercetin-fed mice, triglycerides (TG) were decreased with 14% (p<0.001) and total poly unsaturated fatty acids (PUFA) were increased with 13% (p<0.01). Palmitic acid, oleic acid, and linoleic acid were all decreased by 9-15% (p<0.05) in quercetin-fed mice. Both palmitic acid and oleic acid can be oxidized by omega (?)-oxidation. Gene expression profiling showed that quercetin increased hepatic lipid metabolism, especially ?-oxidation. At the gene level, this was reflected by the up-regulation of cytochrome P450 (Cyp) 4a10, Cyp4a14, Cyp4a31 and Acyl-CoA thioesterase 3 (Acot3). Two relevant regulators, cytochrome P450 oxidoreductase (Por, rate limiting for cytochrome P450s) and the transcription factor constitutive androstane receptor (Car; official symbol Nr1i3) were also up-regulated in the quercetin-fed mice. We conclude that quercetin intake increased hepatic lipid ?-oxidation and lowered corresponding circulating lipid levels, which may contribute to potential beneficial effects on CVD. PMID:23359794

Hoek-van den Hil, Elise F; Keijer, Jaap; Bunschoten, Annelies; Vervoort, Jacques J M; Stankova, Barbora; Bekkenkamp, Melissa; Herreman, Laure; Venema, Dini; Hollman, Peter C H; Tvrzicka, Eva; Rietjens, Ivonne M C M; van Schothorst, Evert M

2013-01-01

347

Intrafamilial Associations of Lipid Profiles and the Role of Nutrition: The Tehran Lipid and Glucose Study  

Microsoft Academic Search

Background: The role of gene and environment in the genesis of abnormal lipid profile is still a controversial issue. Objective: To clarify the importance of certain parental risk factors associated with lipid profiles of children and adolescents. Methods: We conducted this cross-sectional population-based study in district 13 in the east of metropolitan Tehran.One hundred and thirteen eligible families comprising 455

Parvin Mirmiran; Mohammadreza Mirbolooki; Peimaneh Heydarian; Payam Salehi; Fereidoun Azizi

2008-01-01

348

Dietary Structured Lipids and Phytosteryl Esters: Blood Lipids and Cardiovascular Status in Spontaneously Hypertensive Rats  

Microsoft Academic Search

This study examined the dietary effects of enzymatically modified sesame oil with caprylic acid (structured lipids, SL) and\\u000a phytosteryl esters (PE) on blood lipid profiles and cardiovascular parameters of spontaneously hypertensive rats (SHR) fed\\u000a high-fat and high-cholesterol (HFHC) diets. The dietary groups were: normal diet (control), sesame oil (SO), SL, SO fortified\\u000a with PE (SOP), and SL fortified with PE

Byung Hee Kim; Kevin D. Sandock; Tom P. Robertson; Stephen J. Lewis; Casimir C. Akoh

2008-01-01

349

A lipid zipper triggers bacterial invasion  

PubMed Central

Glycosphingolipids are important structural constituents of cellular membranes. They are involved in the formation of nanodomains (“lipid rafts”), which serve as important signaling platforms. Invasive bacterial pathogens exploit these signaling domains to trigger actin polymerization for the bending of the plasma membrane and the engulfment of the bacterium—a key process in bacterial uptake. However, it is unknown whether glycosphingolipids directly take part in the membrane invagination process. Here, we demonstrate that a “lipid zipper,” which is formed by the interaction between the bacterial surface lectin LecA and its cellular receptor, the glycosphingolipid Gb3, triggers plasma membrane bending during host cell invasion of the bacterium Pseudomonas aeruginosa. In vitro experiments with Gb3-containing giant unilamellar vesicles revealed that LecA/Gb3-mediated lipid zippering was sufficient to achieve complete membrane engulfment of the bacterium. In addition, theoretical modeling elucidated that the adhesion energy of the LecA–Gb3 interaction is adequate to drive the engulfment process. In cellulo experiments demonstrated that inhibition of the LecA/Gb3 lipid zipper by either lecA knockout, Gb3 depletion, or application of soluble sugars that interfere with LecA binding to Gb3 significantly lowered P. aeruginosa uptake by host cells. Of note, membrane engulfment of P. aeruginosa occurred independently of actin polymerization, thus corroborating that lipid zippering alone is sufficient for this crucial first step of bacterial host-cell entry. Our study sheds new light on the impact of glycosphingolipids in the cellular invasion of bacterial pathogens and provides a mechanistic explication of the initial uptake processes. PMID:25136128

Eierhoff, Thorsten; Bastian, Björn; Thuenauer, Roland; Madl, Josef; Audfray, Aymeric; Aigal, Sahaja; Juillot, Samuel; Rydell, Gustaf E.; Müller, Stefan; de Bentzmann, Sophie; Imberty, Anne; Fleck, Christian; Römer, Winfried

2014-01-01

350

A lipid zipper triggers bacterial invasion.  

PubMed

Glycosphingolipids are important structural constituents of cellular membranes. They are involved in the formation of nanodomains ("lipid rafts"), which serve as important signaling platforms. Invasive bacterial pathogens exploit these signaling domains to trigger actin polymerization for the bending of the plasma membrane and the engulfment of the bacterium--a key process in bacterial uptake. However, it is unknown whether glycosphingolipids directly take part in the membrane invagination process. Here, we demonstrate that a "lipid zipper," which is formed by the interaction between the bacterial surface lectin LecA and its cellular receptor, the glycosphingolipid Gb3, triggers plasma membrane bending during host cell invasion of the bacterium Pseudomonas aeruginosa. In vitro experiments with Gb3-containing giant unilamellar vesicles revealed that LecA/Gb3-mediated lipid zippering was sufficient to achieve complete membrane engulfment of the bacterium. In addition, theoretical modeling elucidated that the adhesion energy of the LecA-Gb3 interaction is adequate to drive the engulfment process. In cellulo experiments demonstrated that inhibition of the LecA/Gb3 lipid zipper by either lecA knockout, Gb3 depletion, or application of soluble sugars that interfere with LecA binding to Gb3 significantly lowered P. aeruginosa uptake by host cells. Of note, membrane engulfment of P. aeruginosa occurred independently of actin polymerization, thus corroborating that lipid zippering alone is sufficient for this crucial first step of bacterial host-cell entry. Our study sheds new light on the impact of glycosphingolipids in the cellular invasion of bacterial pathogens and provides a mechanistic explication of the initial uptake processes. PMID:25136128

Eierhoff, Thorsten; Bastian, Björn; Thuenauer, Roland; Madl, Josef; Audfray, Aymeric; Aigal, Sahaja; Juillot, Samuel; Rydell, Gustaf E; Müller, Stefan; de Bentzmann, Sophie; Imberty, Anne; Fleck, Christian; Römer, Winfried

2014-09-01

351

Diversity in lipid A binding ligands: comparison of lipid A monoclonal antibodies with rBPI23.  

PubMed

1. Mabs with a high affinity for free lipid A do not bind when it is covalently linked, i.e. in the form of LPS. 2. Lipid A-binding Mabs may be divided into three categories: I. Monoreactive Mabs that bind to the hydrophillic backbone of lipid A II. Polyreactive Kdo Mabs III. Polyreactive Mabs that bind by hydrophobic interactions 3. rBPI23 binds either free or covalently linked lipid A. PMID:8524952

Appelmelk, B J; Qing, A Y; Helmerhorst, E J; Maaskant, J J; Abraham, P R; Thijs, L G; MacLaren, D M

1995-01-01

352

Molecular Dynamics Study of Oxidized Lipid Bilayers in NaCl Solution Viwan Jarerattanachat,  

E-print Network

of oxidized lipids. NaCl disturbed the bilayers with aldehyde lipids more than those with peroxide lipids-dieonyl PCs, and truncated chains of PCs with aldehyde or carboxylic group.9 Both have polar moieties of oxidized lipids.30 Such is the case with lipid lateral diffusion coefficient: Aldehyde lipids diffuse

Wong-Ekkabut, Jirasak

353

n?3 PUFA and membrane microdomains: a new frontier in bioactive lipid research  

Microsoft Academic Search

In recent years, our understanding of the plasma membrane has changed considerably as our knowledge of lipid microdomains has expanded. Lipid microdomains include structures known as lipid rafts and caveolae, which are readily identified by their unique lipid constituents. Cholesterol, sphingolipids and phospholipids with saturated fatty acyl chain moieties are highly enriched in these lipid microdomains. Lipid rafts and caveolae

David W. L. Ma; Jeongmin Seo; Kirsten C. Switzer; Yang-Yi Fan; David N. McMurray; Joanne R. Lupton; Robert S. Chapkin

2004-01-01

354

Mixtures of Cationic Lipid O-Ethylphosphatidylcholine with Membrane Lipids and DNA: Phase Diagrams  

PubMed Central

Ethylphosphatidylcholines are positively charged membrane lipid derivatives, which effectively transfect DNA into cells and are metabolized by the cells. For this reason, they are promising nonviral transfection agents. With the aim of revealing the kinds of lipid phases that may arise when lipoplexes interact with cellular lipids during DNA transfection, temperature-composition phase diagrams of mixtures of the O-ethyldipalmitoylphosphatidylcholine with representatives of the major lipid classes (phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, cholesterol) were constructed. Phase boundaries were determined using differential scanning calorimetry and synchrotron x-ray diffraction. The effects of ionic strength and of DNA presence were examined. A large variety of polymorphic and mesomorphic structures were observed. Surprisingly, marked enhancement of the affinity for nonlamellar phases was observed in mixtures with phosphatidylethanolamine and cholesterol as well as with phosphatidylglycerol (previously reported). Because of the potential relevance to transfection, it is noteworthy that such phases form at close to physiological conditions, and in the presence of DNA. All four mixtures exhibit a tendency to molecular clustering in the gel phase, presumably due to the specific interdigitated molecular arrangement of the O-ethyldipalmitoylphosphatidylcholine gel bilayers. It is evident that a remarkably broad array of lipid phases could arise in transfected cells and that these could have significant effects on transfection efficiency. The data may be particularly useful for selecting possible “helper” lipids in the lipoplex formulations, and in searches for correlations between lipoplex structure and transfection activity. PMID:14507708

Koynova, Rumiana; MacDonald, Robert C.

2003-01-01

355

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

356

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

357

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

358

Lipid Vesicles for the Skin Delivery of Diclofenac: Cerosomes vs. Other Lipid Suspensions  

PubMed Central

Purpose: Lipid suspensions as drug carriers, including conventional liposomes, ethosomes, transferosomes, proniosomes, niosomes, PEG-PPG-PEG niosomes and stratum corneum liposomes (cerosomes), were formulated and compared. Methods: Lipid vesicles were formulated and assessed with regards to enhancement of skin permeation of diclofenac and stability profiles of the formulations. Formulation-induced changes of the biophysical structure of excised human skin were monitored using the Fourier transform infrared spectroscopy. Results: The stability profiles of these suspensions over 12 weeks did not show any significant drug leakage from the vesicles of interest (p > 0.05). FTIR observations indicated that the vesicles increased stratum corneum (SC) lipid fluidization and altered protein conformation. Skin permeability experiments showed that the free unencapsulated drug in the cerosomal formulations caused significant increase in drug permeation across the skin (p < 0.01). Low skin permeability of drug from the other lipid suspensions could be due to the entrapment of diclofenac within these vesicles which decreased the solubility of the hydrophilic drug in the skin lipids and the partition coefficient of the drug from these vesicles into the SC. Conclusion: Optimal drug entrapment in vesicles or alteration of the skin structure may not necessarily enhance the permeation of hydrophilic drugs across the human skin. These lipid vesicles may be further developed into carriers of both hydrophilic and hydrophobic drugs for topical and transdermal delivery, respectively. PMID:25789216

Fathi-Azarbayjani, Anahita; Ng, Kai Xin; Chan, Yew Weng; Chan, Sui Yung

2015-01-01

359

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

360

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

361

Measuring oxidative stress: the confounding effect of lipid concentration in measures of lipid peroxidation.  

PubMed

Lipid peroxidation products are widely used as markers of oxidative damage in the organism. To properly interpret the information provided by these markers, it is necessary to know potential sources of bias and control confounding factors. Here, we investigated the relationship between two indicators of lipid mobilization (circulating levels of triglycerides and cholesterol) and two common markers of oxidative damage (plasma levels of malondialdehyde and hydroperoxides; the latter estimated from the d-ROMs assay kit). The following five avian species were studied: red-legged partridge (Alectoris rufa), zebra finch (Taeniopygia guttata), spotless starling (Sturnus unicolor), marsh harrier (Circus aeroginosus), and Montagu's harrier (Circus pygargus). In all cases, plasma triglyceride levels positively and significantly correlated with lipid peroxidation markers, explaining between 8% and 34% of their variability. Plasma cholesterol, in contrast, showed a significant positive relationship only among spotless starling nestlings and a marginally significant association in zebra finches. These results indicate that lipid peroxidation marker levels covary with circulating lipid levels. We discuss the potential causes and implications of this covariation and recommend that future studies that measure oxidative damage using lipid peroxidation markers report both raw and relative levels (i.e., corrected for circulating triglycerides). Whether the observed pattern also holds for other tissues and in other taxa would deserve further research. PMID:25860832

Pérez-Rodríguez, Lorenzo; Romero-Haro, Ana A; Sternalski, Audrey; Muriel, Jaime; Mougeot, Francois; Gil, Diego; Alonso-Alvarez, Carlos

2015-01-01

362

The role of serum lipids in exudative diabetic maculopathy: is there a place for lipid lowering therapy?  

Microsoft Academic Search

Diabetic maculopathy is a common complication of diabetes mellitus, characterised by macular oedema and frequently accompanied by lipid exudation. It is the major cause of loss of vision from diabetic retinopathy. There is some evidence to implicate serum lipids in exudative maculopathy; cross-sectional studies suggest that higher serum lipid levels are found in patients with macular exudates, and prospective studies

T A Chowdhury; D Hopkins; P M Dodson; G C Vafidis

2002-01-01

363

Sulphur-bearing lipids for the covalent attachment of supported lipid bilayers to gold surfaces: a detailed characterisation and analysis  

Microsoft Academic Search

In a recent paper, a new class of synthetic lipids, which self-assemble to form monolayers on gold surfaces, was introduced. The addition of a monolayer of phospholipids to these layers results in robust supported lipid bilayers designed to reconstitute transmembrane proteins. This paper presents a detailed characterisation of the monolayers and bilayers formed by these lipids and assesses their ability

Claus Duschl; Martha Liley; Holger Lang; Azin Ghandi; Shaik M. Zakeeruddin; Henning Stahlberg; Jacques Dubochet; Axel Nemetz; Wolfgang Knoll; Horst Vogel

1996-01-01

364

Characterization of the Lateral Distribution of Fluorescent Lipid in Binary-Constituent Lipid Monolayers by Principal Component Analysis  

PubMed Central

Lipid lateral organization in binary-constituent monolayers consisting of fluorescent and nonfluorescent lipids has been investigated by acquiring multiple emission spectra during measurement of each force-area isotherm. The emission spectra reflect BODIPY-labeled lipid surface concentration and lateral mixing with different nonfluorescent lipid species. Using principal component analysis (PCA) each spectrum could be approximated as the linear combination of only two principal vectors. One point on a plane could be associated with each spectrum, where the coordinates of the point are the coefficients of the linear combination. Points belonging to the same lipid constituents and experimental conditions form a curve on the plane, where each point belongs to a different mole fraction. The location and shape of the curve reflects the lateral organization of the fluorescent lipid mixed with a specific nonfluorescent lipid. The method provides massive data compression that preserves and emphasizes key information pertaining to lipid distribution in different lipid monolayer phases. Collectively, the capacity of PCA for handling large spectral data sets, the nanoscale resolution afforded by the fluorescence signal, and the inherent versatility of monolayers for characterization of lipid lateral interactions enable significantly enhanced resolution of lipid lateral organizational changes induced by different lipid compositions. PMID:20414462

Sugár, István P.; Zhai, Xiuhong; Boldyrev, Ivan A.; Molotkovsky, Julian G.; Brockman, Howard L.; Brown, Rhoderick E.

2010-01-01

365

Cytosolic StAR-related lipid transfer domain 4 (STARD4) protein influences keratinocyte lipid phenotype and differentiation status  

Microsoft Academic Search

Terminally differentiating keratinocytes actively synthesize and accumulate cholesterol, which is a key constituent of intercellular lipid lamellae which contribute to the epidermal permeability barrier. While the pathway for cholesterol biosynthesis is established, intracellular transport mechanisms for this lipid are poorly understood, despite their importance in regulating organelle sterol content, keratinocyte differentiation status and the activity of lipid-responsive transcription factors involved

H. M. Elbadawy; Faye Borthwick; Catherine Wright; Patricia E. M. Martin; Annette Graham

2011-01-01

366

Adsorption of Human Tear Lipocalin to Human Meibomian Lipid Films  

PubMed Central

Purpose Tear lipocalin (Tlc) is a major lipid binding protein in tears and is thought to have an important role in stabilizing the Meibomian lipid layer by transferring lipids to it from the aqueous layer or ocular surface, or by adsorbing to it directly. These possible roles have been investigated in vitro using human Tlc. Methods Tlc was purified from human tears by size exclusion chromatography followed by ion exchange chromatography. Three additional samples of the Tlc were prepared by lipidation, delipidation, and relipidation. The lipids extracted from the purified Tlc were analyzed by HPLC-MS followed by fragmentation. Adsorption of these different forms of Tlc to a human Meibomian lipid film spread on the surface of an artificial tear buffer in a Langmuir trough were observed by recording changes in the pressure with time (?-T profile) and monitoring the appearance of the film microscopically. These results were compared with similar experiments using a bovine Meibomian lipid film. Results The results indicated that Tlc binds slowly to a human Meibomian lipid film compared with lysozyme or lactoferrin, even at 37°C. The adsorption of Tlc to a human Meibomian lipid film was very different from its adsorption to a bovine Meibomian lipid film, indicating the nature of the lipids in the film is critical to the adsorption process. Similarly, the different forms of Tlc had quite distinct adsorption patterns, as indicated both by changes in ?-T profiles and the microscopic appearance of the films. Conclusions It was concluded that human Tlc was capable of adsorbing to and penetrating into a Meibomian lipid layer, but this process is very complex and depends on both the types of lipids bound to Tlc and the lipid complement comprising the Meibomian lipid film. PMID:18757516

Millar, Thomas J.; Mudgil, Poonam; Butovich, Igor A.; Palaniappan, Chendur K.

2009-01-01

367

The effects of dietary lipid amount and fatty-acid composition on the digestibility of lipids by the prawn, Penaeus monodon  

Microsoft Academic Search

The digestibilities of the lipid content, and the fatty acids of this lipid, were examined in each of a series of the diets designed to examine the optimal fatty-acid and lipid requirements for the giant tiger prawn, Penaeus monodon. Digestibility of the total lipids was similar for dietary lipid levels of 45, 75 and 105 g kg?1 though the digestibility

B. D. Glencross; D. M. Smith; M. R. Thomas; K. C. Williams

2002-01-01

368

Screening of Lipid Carriers and Characterization of Drug-Polymer-Lipid Interactions for the Rational Design of Polymer-Lipid Hybrid Nanoparticles (PLN)  

Microsoft Academic Search

Purpose  The thermodynamics and solid state properties of components and their interactions in a formulation for polymer-lipid hybrid nanoparticles (PLN) were characterized for screening lead lipid carriers and rational design of PLN.Methods  Verapamil HCl (VRP) was chosen as a model drug and dextran sulfate sodium (DS) as a counter-ionic polymer. Solubility parameters of VRP, VRP-DS complex, and various lipids were calculated and

Yongqiang Li; Nicolas Taulier; Andrew M. Rauth; Xiao Yu Wu

2006-01-01

369

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

370

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

371

Lipid accumulation and dendritic cell dysfunction in cancer  

PubMed Central

Professional antigen presenting cells, dendritic cells (DC) are responsible for initiation and maintenance of immune responses. Here, we report that a substantial proportion of DCs in tumor-bearing mice and cancer patients have increased levels of triglycerides. Lipid accumulation in DCs was caused by increased uptake of extracellular lipids due to up-regulation of scavenger receptor A. DCs with high lipid content were not able to effectively stimulate allogeneic T cells or present tumor-associated antigens. DCs with high and normal lipid levels did not differ in expression of MHC and co-stimulatory molecules. However, lipid-laden DCs had reduced capacity to process antigens. Pharmacological normalization of lipid levels in DCs with an inhibitor of acetyl-CoA carboxylase restored the functional activity of DCs and substantially enhanced the effects of a cancer vaccine. These findings support the regulation of immune responses in cancer by manipulation of lipid levels in DCs. PMID:20622859

Herber, Donna L.; Cao, Wei; Nefedova, Yulia; Novitskiy, Sergey V.; Nagaraj, Srinivas; Tyurin, Vladimir A.; Corzo, Alex; Cho, Hyun Il; Celis, Esteban; Lennox, Briana; Knight, Stella C.; Padhya, Tapan; McCaffrey, Thomas V.; McCaffrey, Judith C.; Antonia, Scott; Fishman, Mayer; Ferris, Robert L.; Kagan, Valerian E.; Gabrilovich, Dmitry I.

2010-01-01

372

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

373

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

374

Control of lipid metabolism by Tachykinin in Drosophila  

PubMed Central

Summary 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 the TKR99D receptor and 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

2015-01-01

375

Lipid composition of squirrel monkey (Saimiri sciureus) saliva.  

PubMed

The content and composition of lipids in saliva of healthy caries-free squirrel monkeys were investigated. The dialyzed and lyophilized saliva on extraction with chloroform/methanol yielded 8.0 +/- 0.9 mg of lipids/100 ml of saliva. Following fractionation on silicic acid column, 30.9% of lipids were found in the neutral lipid fraction, 58.8% in the glycolipid fraction, and 10.3% in the phospholipid fraction. The neutral lipids exhibited high content of free fatty acids (58.8%) and triglycerides (23.3%), the glycolipids consisted mainly of neutral and sulfated glyceroglucolipids (95%), while the phospholipids were rich in sphingomyelin and phosphatidylcholine. The results show that squirrel monkey saliva, while displaying lipid content similar to that of caries-susceptible humans, contains 50% less lipids than saliva of periodontal disease-prone marmoset. PMID:3930141

Murty, V L; Slomiany, B L; Slomiany, A; Jozwiak, Z; Kosmala, M; Mandel, I D

1985-01-01

376

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

PubMed

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

H?c-Wydro, Katarzyna; Wydro, Pawe?; Cetnar, Andrzej; W?odarczyk, Grzegorz

2015-02-01

377

Low levels of lipid oxidation radically increase the passive permeability of lipid bilayers.  

PubMed

Oxidation of unsaturated lipids in cellular membranes has been shown to cause severe membrane damage and potentially cell death. The presence of oxidized lipid species in the membrane is known to cause changes in membrane properties, such as decreased fluidity. This study uses giant unilamellar vesicles (GUVs) to measure passive transport across membranes containing defined concentrations of oxidized lipid species. GUVs consisting of a saturated phospholipid, an unsaturated phospholipid, and cholesterol were used as model membranes. By replacing defined amounts of the unsaturated lipid with a corresponding oxidized product, the oxidation process could be mimicked, yielding vesicles of varying oxidized lipid concentration. Oxidized lipid concentration was varied from 0 mol% to 18 mol% of the total lipid concentration. Passive transport of PEG12-NBD, an uncharged fluorescent molecule, was measured using a microfluidic trap to capture the GUVs and spinning disk confocal microscopy (SDCM) to track the transport of a fluorescent species in the equatorial plane of each GUV. Membrane permeability was determined by fitting the resulting concentration profiles to a finite difference model of diffusion and permeation around and through the membrane. Experiments showed three permeability regimes. Without oxidation, transport was slow, with a measured permeability on the order of 1.5 × 10(-6) cm s(-1). At 2.5-10% oxidized species permeation was fast (1.5 × 10(-5) cm s(-1)). Above 12.5% oxidized species, the bilayer was disrupted by the formation of pore defects. As passive transport is an important mechanism for drug delivery, understanding the relationship between oxidation and permeation could provide insight into the pharmaceutical characteristics of tissues with oxidative damage. PMID:25415555

Runas, Kristina A; Malmstadt, Noah

2015-01-21

378

Structure of a lipid-bound Extended-Synaptotagmin indicates a role in lipid transfer  

PubMed Central

Growing evidence suggests that close appositions between the endoplasmic reticulum (ER) and other membranes, including appositions with the plasma membrane (PM), mediate exchange of lipids between the two bilayers. The mechanisms of such exchange, which allows lipid transfer independently of vesicular transport, remain poorly understood. The presence of an SMP (synaptotagmin-like-mitochondrial-lipid binding protein) domain, a proposed lipid binding module, in several proteins localized at membrane contact sites raised the possibility that such domains may be implicated in lipid transport1,2. SMP-containing proteins include components of the ERMES complex, an ER-mitochondrial tether3, and the Extended-Synaptotagmins/tricalbins, which are ER-PM tethers4-6. Here we present at 2.44 Å resolution the crystal structure of a fragment of Extended-Synaptotagmin 2 (E-Syt2), including an SMP domain and two adjacent C2 domains. The SMP domain has a beta-barrel structure like protein modules in the TULIP superfamily. It dimerizes to form a ~90 Å long cylinder traversed by a channel lined entirely with hydrophobic residues, with the two C2A-C2B fragments forming arched structures flexibly linked to the SMP domain. Importantly, structural analysis complemented by mass spectrometry revealed the presence of glycerophospholipids in the E-Syt2 SMP channel, indicating a direct role for E-Syts in lipid transport. These findings provide strong evidence for a role of SMP domain containing proteins in the control of lipid transfer at membrane contact sites and have broad implication beyond the field of ER to PM appositions. PMID:24847877

Schauder, Curtis M.; Wu, Xudong; Saheki, Yasunori; Narayanaswamy, Pradeep; Torta, Federico; Wenk, Markus R.; De Camilli, Pietro; Reinisch, Karin M.

2014-01-01

379

Lipid production of Chlorella vulgaris from lipid-extracted microalgal biomass residues through two-step enzymatic hydrolysis.  

PubMed

Lipid-extracted microalgal biomass residues (LMBRs) were treated using cellulase, neutrase and alcalase in a two-step process and the resulting hydrolysates were used as a source of nutrients for the cultivation of Chlorella vulgaris under non-aerated and aerated conditions for lipid production. Aeration was favorable for cell growth and lipid accumulation and a biomass of approximately 3.28 g L(-1), lipid content of 35% and lipid productivity of 116 mg L(-1) d(-1) were obtained. Thus, the tested mode of LMBRs utilization was effective for nutrient recycling in microalgal biodiesel production. PMID:22609706

Zheng, Hongli; Gao, Zhen; Yin, Fengwei; Ji, Xiaojun; Huang, He

2012-08-01

380

Structural characterization of cationic lipid–tRNA complexes  

PubMed Central

Despite considerable interest and investigations on cationic lipid–DNA complexes, reports on lipid–RNA interaction are very limited. In contrast to lipid–DNA complexes where lipid binding induces partial B to A and B to C conformational changes, lipid–tRNA complexation preserves tRNA folded state. This study is the first attempt to investigate the binding of cationic lipid with transfer RNA and the effect of lipid complexation on tRNA aggregation and condensation. We examine the interaction of tRNA with cholesterol (Chol), 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP), dioctadecyldimethylammoniumbromide (DDAB) and dioleoylphosphatidylethanolamine (DOPE), at physiological condition, using constant tRNA concentration and various lipid contents. FTIR, UV-visible, CD spectroscopic methods and atomic force microscopy (AFM) were used to analyze lipid binding site, the binding constant and the effects of lipid interaction on tRNA stability, conformation and condensation. Structural analysis showed lipid–tRNA interactions with G–C and A–U base pairs as well as the backbone phosphate group with overall binding constants of KChol = 5.94 (± 0.8) × 104 M–1, KDDAB = 8.33 (± 0.90) × 105 M–1, KDOTAP = 1.05 (± 0.30) × 105 M–1 and KDOPE = 2.75 (± 0.50) × 104 M–1. The order of stability of lipid–tRNA complexation is DDAB > DOTAP > Chol > DOPE. Hydrophobic interactions between lipid aliphatic tails and tRNA were observed. RNA remains in A-family structure, while biopolymer aggregation and condensation occurred at high lipid concentrations. PMID:19561199

Marty, Regis; N’soukpoé-Kossi, Christophe N.; Charbonneau, David M.; Kreplak, Laurent; Tajmir-Riahi, Heidar-Ali

2009-01-01

381

Severe alterations in lipid composition of frontal cortex lipid rafts from Parkinson's disease and incidental Parkinson's disease.  

PubMed

Lipid rafts are cholesterol- and sphingomyelin-enriched microdomains that provide a highly saturated and viscous physicochemical microenvironment to promote protein-lipid and protein-protein interactions. We purified lipid rafts from human frontal cortex from normal, early motor stages of Parkinson's disease (PD) and incidental Parkinson's disease (iPD) subjects and analyzed their lipid composition. We observed that lipid rafts from PD and iPD cortices exhibit dramatic reductions in their contents of n-3 and n-6 long-chain polyunsaturated fatty acids, especially docosahexaenoic acid (22:6-n3) and arachidonic acid (20:4n-6). Also, saturated fatty acids (16:0 and 18:0) were significantly higher than in control brains. Paralleling these findings, unsaturation and peroxidability indices were considerably reduced in PD and iPD lipid rafts. Lipid classes were also affected in PD and iPD lipid rafts. Thus, phosphatidylserine and phosphatidylinositol were increased in PD and iPD, whereas cerebrosides and sulfatides and plasmalogen levels were considerably diminished. Our data pinpoint a dramatic increase in lipid raft order due to the aberrant biochemical structure in PD and iPD and indicate that these abnormalities of lipid rafts in the frontal cortex occur at early stages of PD pathology. The findings correlate with abnormal lipid raft signaling and cognitive decline observed during the development of these neurodegenerative disorders. PMID:21717034

Fabelo, Noemí; Martín, Virginia; Santpere, Gabriel; Marín, Raquel; Torrent, Laia; Ferrer, Isidre; Díaz, Mario

2011-01-01

382

[Optimal lipid treatment: possibilities and current limitations].  

PubMed

Prevention is a major contributor to the decline in cardiovascular morbidity and mortality. Cardiovascular diseases still are the leading cause of death (42%) in Germany and indicate unmet preventive needs. Limitations of healthy lifestyle, the basis of many recommendations, include insufficient compliance and efficacy in individual cases. In their latest metaanalysis the Cholesterol Treatment Trialists' Collaborators showed updated estimates of treatment effects of statins including more or less intensive regimens.The average reduction in major vascular events was 21% per 1.0 mmol/l reduction in LDL cholesterol. Appropriateness of receiving lipid modulating treatment in the population will be discussed in the light of controversial recommendations in treatment strategies. Residual risk in statin treated patients may be ameliorated by options beyond LDL-lowering. Suggestions for clinical practice are provided on the background of clinical relevant characteristics of current lipid lowering drugs and future developments are outlined. PMID:21331642

Klose, G

2011-03-01

383

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

384

Capsinoids suppress fat accumulation via lipid metabolism  

PubMed Central

Capsaicin, found in red peppers, has been reported to have anti-obesity, anti-hypertension, anti-diabetes and anti-inflammatory functions. In the present study, we determined the effect of non-pungent capsinoids on the metabolism of adipocytes. We demonstrated that capsinoids suppressed fat accumulation in vivo and in vitro in mice. Liver, the main tissue of lipid metabolism, was treated by capsinoids, and HMG-CoA reductase, CPT-1, FAT/CD36 and GLUT4 were found to be increased significantly, which demonstrated promotion of the lipid metabolism in liver and adipose tissues. In addition, by adding capsinoids, the induced adipocytes also demonstrated significantly increased levels of HMG-CoA reductase, CPT-1, FAT/CD36 and GLUT4. Oil red O staining also demonstrated that capsinoids decreased fat accumulation in the adipocytes. In conclusion, these results indicate that capsinoids may be worth investigating as a potential cure for obesity. PMID:25421144

HONG, QIN; XIA, CHEN; XIANGYING, HU; QUAN, YUAN

2015-01-01

385

Analysis of the Lipids of Mycobacterium tuberculosis.  

PubMed

Mycobacterial cell wall ultrastructure has been studied through the use of negative staining, electron microscopy (1,2), freeze fracture (3), X-ray diffraction (4), differential scanning calorimetry (5,6), and electron spin resonance spectroscopy. Through the use of these techniques, the cellular envelope has been shown to be highly ordered and organized in a tripartite structure (2,3,7,8). Classical freeze-fracture and freeze-etch electron microscopy studies have established that fragmentation takes place along extended lipid-rich nonaqueous domains. Applied to mycobacteria, these techniques have revealed two fracture sites, an inner cleavage plane within the plasmalamellar membrane and an outer cleavage plane between the mycolic acids and the tenuous outer leaflet (1). These two cleavage sites represent the two domains containing the majority of the lipid material of the bacillus. PMID:21341079

Slayden, R A; Barry, C E

2001-01-01

386

Epoxy acetylenic lipids: their analogues and derivatives.  

PubMed

Currently, approximately 250 natural acetylenic epoxy structures are known. The present review describes research concerning biologically active epoxy acetylenic lipids and related compounds isolated from different sources. Intensive searches for new classes of pharmacologically potent agents produced by living organisms have resulted in the discovery of dozens of such compounds that possess high anticancer, cytotoxic, antibacterial, antiviral, and other activities. Acetylenic epoxides primarily belong to a class of molecules containing triple bond(s) and epoxy group(s) belonging to different lipid classes and/or other groups. This review emphasises natural and synthetic acetylenic epoxides and other related compounds as important sources of leads for drug discovery. The present review is the first article devoted to natural acetylenic epoxides. PMID:25193612

Kuklev, Dmitry V; Dembitsky, Valery M

2014-10-01

387

Lysosome: regulator of lipid degradation pathways  

PubMed Central

Autophagy is a catabolic pathway that has a fundamental role in the adaptation to fasting and primarily relies on the activity of the endolysosomal system, to which the autophagosome targets substrates for degradation. Recent studies have revealed that the lysosomal–autophagic pathway plays an important part in the early steps of lipid degradation. In this review, we discuss the transcriptional mechanisms underlying co-regulation between lysosome, autophagy, and other steps of lipid catabolism, including the activity of nutrient-sensitive transcription factors (TFs) and of members of the nuclear receptor family. In addition, we discuss how the lysosome acts as a metabolic sensor and orchestrates the transcriptional response to fasting. PMID:25061009

Settembre, Carmine; Ballabio, Andrea

2014-01-01

388

Lipids as universal biomarkers of extraterrestrial life.  

PubMed

In 1965, James Lovelock published a general statement, based on thermodynamic chemical equilibrium principles, about how to detect extant or extinct life on a planet other than Earth. Nearly 50 years later, it is possible to make such measurements with robotic missions such as current and future Mars rovers, and probes to sample icy plumes of Enceladus or Europa. We make a specific recommendation that certain characteristic patterns in the composition of lipid hydrocarbons can only result from a biological process, because the signal arises from a universal requirement related to lipid bilayer fluidity and membrane stability. Furthermore, the pattern can be preserved over millions of years, and instrumentation is already available to be incorporated into flight missions. PMID:24735484

Georgiou, Christos D; Deamer, David W

2014-06-01

389

Anisotropic spontaneous curvatures in lipid membranes  

NASA Astrophysics Data System (ADS)

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.

Walani, Nikhil; Torres, Jennifer; Agrawal, Ashutosh

2014-06-01

390

Industrial wastes as a promising renewable source for production of microbial lipid and direct transesterification of the lipid into biodiesel.  

PubMed

Two strategies of converting industrial wastes to microbial lipid and direct transesterification of obtained lipid into biodiesel were attempted. Several oleaginous yeasts were cultivated on industrial wastes. The yeasts grew well on the wastes with low C/N ratio (i.e. serum latex) but accumulated high lipid content only when the wastes had a high C/N ratio (i.e. palm oil mill effluent and crude glycerol). The yeast lipids have similar fatty acid composition to that of plant oil indicating their potential use as biodiesel feedstocks. The combination of these wastes and two-phase cultivation for cell growth and lipid accumulation improved lipid productivity of the selected yeast. The direct transesterification process that eliminates cell drying and lipid extraction steps, gave comparable yield of biodiesel (fatty acid methyl ester >70% within 1h) to that of conventional method. These two successful strategies may contribute greatly to industrializing oil production from microbes and industrial wastes. PMID:23747444

Cheirsilp, Benjamas; Louhasakul, Yasmi

2013-08-01

391

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

392

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

393

Parenteral lipids: safety aspects and toxicity.  

PubMed

Lipid emulsions (LEs) used in modern parenteral nutrition formulations are indispensable sources of calories and (essential) fatty acids ((E)FAs). Several generations of LEs based on various FA sources have been developed, and issues related to their safe use deserve attention. The relevant issues concern LE composition, stability and sterility, while other problems are related to the lipid infusion rate, including hypertriglyceridemia and lipid overload syndrome. The FA structure of LEs translates into effects on inflammatory processes and immune cell function and affects the functions of organs, such as the liver and lungs. In addition, disturbed balances of (anti)oxidants and the presence of other bioactive agents in LEs, such as phytosterols, are mechanisms that may underlie the potential adverse effects. Lipid emulsions (LEs) are key components of parenteral nutrition (PN) that bypass the need for (essential) fatty acids ((E)FAs) and provide sufficient energy to decrease the need for the infusion of large amounts of dextrose, thus preventing its associated complications. The oldest available LEs are based on soybean oil (SO-LE) and meet these requirements. (Pre)clinical evidence suggests that various, next-generation LEs based on alternative oil sources are safe and effective; particularly, those based on fish oil (FO-LEs) have less pro-inflammatory characteristics that may convey beneficial effects on the immune system and organ functions. With the exception of decreased liver damage with the use of FO-LEs instead of SO-LEs, the clinical relevance of many of these data needs further validation. PMID:25471803

Wanten, Geert J A

2015-01-01

394

Membrane Lipid Biosynthesis in Purple Bacteria  

Microsoft Academic Search

Membranes are essential to all living cells. They provide the boundary to the surrounding environment, allow the controlled\\u000a exchange of compounds through membrane transporters, and serve as a matrix for membrane associated enzymes and protein complexes\\u000a involved in the generation of energy or communication with the environment. Biomembranes are built from amphipathic, polar\\u000a lipids that either on their own or

Banita Tamot; Christoph Benning

395

Indications for lipid-lowering drugs  

Microsoft Academic Search

Summary  There is overwhelming evidence from prospective studies that plasma cholesterol levels are exponentially related to coronary\\u000a artery disease (CAD) risk. Inversely, the beneficial effect of lowering plasma cholesterol is convincingly established from\\u000a major clinical trials. A consensus has been reached in a large number of countries on the need to lower plasma lipid levels,\\u000a especially LDL-cholesterol, to delay the onset,

J. Davignon

1991-01-01

396

Fractionation of hydrogen isotopes in lipid biosynthesis  

Microsoft Academic Search

Isotopic compositions of carbon-bound hydrogen in individual compounds from eight different organisms were measured using isotope-ratio-monitoring gas chromatography–mass spectrometry. This technique is capable of measuring D\\/H ratios at natural abundance in individual lipids yielding as little as 20 nmol of H2, and is applicable to a wide range of compounds including hydrocarbons, sterols, and fatty acids. The hydrogen isotopic compositions of

Alex L. Sessions; Thomas W. Burgoyne; Arndt Schimmelmann; John M. Hayes

1999-01-01

397

Oxidation of lipids in fish meal  

Microsoft Academic Search

Oxidation of lipids in fish meal has been studied. The course of the reaction has been followed by means of oxygen absorption,\\u000a peroxide values and chromatographic analyses. The latter has been used quantitatively, because the method of methylation of\\u000a the unreacted fatty acids obtained by hydrolysis of the glyceryl esters has proved to the quantitative. The results indicate:\\u000a (a) there

Mario D. Waissbluth; Lucy Guzman; Florencio P. Plachco

1971-01-01

398

Abundant Lipid and Protein Components of Drusen  

Microsoft Academic Search

BackgroundDrusen are extracellular lesions characteristic of aging and age-related maculopathy, a major retinal disease of the elderly. We determined the relative proportions of lipids and proteins in drusen capped with retinal pigment epithelium (RPE) and in RPE isolated from non-macular regions of 36 human retinas with grossly normal maculas obtained <6 hr after death.Methodology\\/Principal FindingsDruse pellets were examined by light

Lan Wang; Mark E. Clark; David K. Crossman; Kyoko Kojima; Jeffrey D. Messinger; James A. Mobley; Christine A. Curcio

2010-01-01

399

Intravenous lipids in home parenteral nutrition.  

PubMed

Intravenous lipid emulsions (IVLEs) are an important component of the nutritional admixtures for patients on long-term home parenteral nutrition (HPN) for chronic intestinal failure (CIF). IVLEs are primarily used as a source of energy and essential fatty acids, and the content of polyunsaturated fatty acids (PUFAs) is the most important characteristic of IVLEs. IVLEs rich in n-6 PUFAs may have a pro-inflammatory effect, whereas those rich in n-3 PUFAs may exert an anti-inflammatory effect. Other components to be considered are the risk of lipid peroxidation and the contents of ?-tocopherol and phytosterols. Published studies were reviewed to determine the effects of the commercially available IVLEs on essential fatty acid status, liver function tests, lipid peroxidation and inflammatory indices, and ?-tocopherol status, as well as their clinical safety and efficacy in patients on HPN. Investigations on the efficacy of fish oil-based IVLEs, which are rich in n-3 PUFAs, in the treatment of parenteral nutrition-associated liver disease (PNALD) in adult patients on HPN for CIF were also analyzed. The current commercial IVLE formulations have similar clinical safety profiles and efficacies and can prevent the development of essential fatty acid deficiency in adults on HPN for CIF. IVLE with a low content of n-6 PUFAs and with or without increased n-3 PUFA content may reduce the risk of PNALD. Fish oil-based IVLE, which is rich in n-3 PUFAs, may be effective in reversing hepatic cholestasis due to PNALD. PMID:25471810

Pironi, Loris; Agostini, Federica; Guidetti, Mariacristina

2015-01-01

400

Stiffened lipid platforms at molecular force foci  

PubMed Central

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

2013-01-01

401

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

402

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

W?glarz, Ludmi?a; Dzier?ewicz, Zofia

2013-01-01

403

Crystallizing Membrane Proteins Using Lipidic Mesophases  

PubMed Central

A detailed protocol for crystallizing membrane proteins that makes use of lipidic mesophases is described. This has variously been referred to as the lipid cubic phase or in meso method. The method has been shown to be quite general in that it has been used to solve X-ray crystallographic structures of prokaryotic and eukaryotic proteins, proteins that are monomeric, homo- and hetero-multimeric, chromophore-containing and chromophore-free, and ?-helical and ?-barrel proteins. Its most recent successes are the human engineered ?2-adrenergic and adenosine A2A G protein-coupled receptors. Protocols are provided for preparing and characterizing the lipidic mesophase, for reconstituting the protein into the monoolein-based mesophase, for functional assay of the protein in the mesophase, and for setting up crystallizations in manual mode. Methods for harvesting micro-crystals are also described. The time required to prepare the protein-loaded mesophase and to set up a crystallization plate manually is about one hour. PMID:19390528

Caffrey, Martin; Cherezov, Vadim

2009-01-01

404

Lipid diffusibility in the intact erythrocyte membrane.  

PubMed Central

The lateral diffusion of fluorescent lipid analogues in the plasma membrane of intact erythrocytes from man, mouse, rabbit, and frog has been measured by fluorescence photobleaching recovery (FPR). Intact cells from dystrophic, normoblastic, hemolytic, and spherocytotic mouse mutants; from hypercholesterolemic rabbits and humans; and from prenatal, neonatal, and juvenile mice have been compared with corresponding normals. The lateral diffusion coefficient (D) for 3,3'-dioctadecylindodicarbocyanine iodide (DiI[5]) in intact normal human erythrocytes is D = 8.2 +/- 1.2 X 10(-9) cm2/s at 25 degrees C and D = 2.1 +/- 0.4 X 10(-8) cm2/s at 37 degrees C, and varies approximately 50-fold between 1 degree and 42 degrees C. The diffusion constants of lipid analogue rhodamine-B phosphatidylethanolamine (RBPE) are about twice those of DiI[5]. The temperature dependence and magnitude of D vary by up to a factor of 3 between species and are only influenced by donor age in prenatals. DiI[5] diffusibility is not perturbed by the presence of calcium or local anesthetics or by spectrin depletion (via mutation). However, lipid-analogue diffusibility in erythrocyte ghosts may differ from intact cells. Dietary hypercholesterolemia in rabbits reduces the diffusion coefficient and eliminates the characteristic break in Arrhenius plots of D found in all other cells studied except frog. PMID:6603237

Bloom, J A; Webb, W W

1983-01-01

405

Tumor-induced alterations in lipid metabolism.  

PubMed

Alterations of lipid metabolism have been increasingly recognized as a hallmark of cancer cells. Cancer cells esterify fatty acids predominantly to phospholipids, an essential component of cell membranes. The main pathway along which proliferating cells gain lipids for membrane synthesis is the endogenous mevalonate pathway. Increased synthesis of mevalonate and mevalonate-derived isoprenoids supports increased cell proliferation through activating growth-regulatory proteins and oncoproteins and promoting DNA synthesis. The importance of a better knowledge of metabolic changes in lipogenic enzymes pathways, as well as of the role of each biochemical pathway in carcinogenesis, provides the rationale for in-depth study of the oncogenic signaling important for the initiation and progression of tumors. The dependence of tumor cells on a dysregulated lipid metabolism suggests that the proteins involved in this process may be excellent chemotherapeutic targets for cancer treatment. Here, we confirm the vital link between lipogenesis and cell proliferation, and our recent findings suggest that nutritional intervention is an effective and safe way to reduce cell proliferation in experimental models of carcinogenesis. The olive oil diet significantly reduces the protein activities of lipogenic enzymes associated with cell growth. The use of natural dietary components could potentially assist in the management of subjects with metabolic disorders-related tumors. PMID:24606524

Notarnicola, M; Tutino, V; Caruso, M G

2014-01-01

406

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

PubMed Central

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.

2014-01-01

407

Nicotinic acid regulates glucose and lipid metabolism through lipid independent pathways.  

PubMed

Nicotinic acid (NA) decreases low density lipoprotein (LDL) cholesterol and increases highdensity lipoprotein (HDL) cholesterol at pharmacological doses 500-2000 mg/day, which further inhibits the progression of atherosclerosis and cardiovascular morbidity. However, some effects of NA may be mediated through lipid-independent pathways. NA participates in the regulation of glucose metabolism and the NAD-sirtuin pathway, which may relate to the altered mitochondrial biogenesis. NA exerts its anti-atherosclerotic or side effects via binding to GPR109A and receptor TRPV1. NA may regulate lipid metabolism via adipokines, especially TNF? and adiponectin. NA participates in several cellular pathways, including forkhead transcription factors, sirtuins, and protein kinase B. Though much progress on the regulatory effect of NA has been obtained, much remains to be determined about the exact cellular signal pathways on the regulatory mechanism. To reveal the mechanisms of excessive fatty deposition diseases, it is necessary to investigate the signaling pathways in the muscle, liver, and adipose tissue by which NA controls lipid metabolism. In this paper, we will review recent data on the pharmacological effects of NA and discuss how NA might be harnessed to regulate glucose and lipid metabolism through lipid-independent pathways. PMID:25429652

Liu, Dongwu; Wang, Xiaoqian; Kong, Ling; Chen, Zhiwei

2015-01-01

408

RNA Interference Silencing of a Major Lipid Droplet Protein Affects Lipid Droplet Size in Chlamydomonas reinhardtii? †  

PubMed Central

Eukaryotic cells store oils in the chemical form of triacylglycerols in distinct organelles, often called lipid droplets. These dynamic storage compartments have been intensely studied in the context of human health and also in plants as a source of vegetable oils for human consumption and for chemical or biofuel feedstocks. Many microalgae accumulate oils, particularly under conditions limiting to growth, and thus have gained renewed attention as a potentially sustainable feedstock for biofuel production. However, little is currently known at the cellular or molecular levels with regard to oil accumulation in microalgae, and the structural proteins and enzymes involved in the biogenesis, maintenance, and degradation of algal oil storage compartments are not well studied. Focusing on the model green alga Chlamydomonas reinhardtii, the accumulation of triacylglycerols and the formation of lipid droplets during nitrogen deprivation were investigated. Mass spectrometry identified 259 proteins in a lipid droplet-enriched fraction, among them a major protein, tentatively designated major lipid droplet protein (MLDP). This protein is specific to the green algal lineage of photosynthetic organisms. Repression of MLDP gene expression using an RNA interference approach led to increased lipid droplet size, but no change in triacylglycerol content or metabolism was observed. PMID:19915074

Moellering, Eric R.; Benning, Christoph

2010-01-01

409

Morphological effect of lipid carriers on permeation of lidocaine hydrochloride through lipid membranes.  

PubMed

We have studied how the transdermal delivery of lidocaine hydrochloride (LHC) is affected by the morphology of lipid carriers, liposomes and micelles, having the same lipid composition of 1-stearoyl-sn-glycero-3-phosphocholine (LPC) and cholesteryl hemisuccinate (CHEMS). In vitro drug permeation study, carried out on guinea pig skin, has revealed that the liposomes made of LPC and CHEMS significantly enhance the permeation rate of entrapped LHC; by contrast, the mixed micelles with the same composition decrease the degree of delivering co-existing LHC. Basically, we have also investigated the release kinetics of LHC through the cellulose membrane and found that both liposomes and micelles have a similar releasing profile. To experimentally demonstrate this unique behavior, we have observed the fluidity of stratum corneum liposomal membranes in the presence of either our liposomes or micelles. From this study, we have found that LPC/CHEMS liposomes fluidize the lipid membrane of stratum corneum lipids; however, lipid micelles rather make the membrane rigid. These findings highlight that controlling the morphology of drug carriers provides us with a means to modulate the permeability of encapsulated drug molecules. PMID:20060459

Shim, Jongwon; Kim, Mi Jin; Kim, Han-Kon; Kim, Do-Hoon; Oh, Seong Geun; Ko, Seung Yong; Jang, Ho Gyeom; Kim, Jin-Woong

2010-03-30

410

Fatty acid composition and lipid peroxidation of soft-shelled turtle, Pelodiscus sinensis, fed different dietary lipid sources.  

PubMed

Juvenile soft-shelled turtles (Pelodiscus sinensis) were fed 7 diets containing 8% of lard, soybean oil, olive oil, menhaden fish oil, or mixtures of 1 to 1 ratio of fish oil and lard, soybean oil, olive oil for 10 weeks. Growth and muscle proximate compositions of the turtles were not affected by different dietary treatments (p>0.05). Fatty acid profiles in muscle polar lipids, muscle non-polar lipids, and liver polar lipids reflected the fatty acid composition of dietary lipid source. Turtles fed diets containing fish oil generally contained significantly higher (p<0.05) proportion of highly unsaturated fatty acids (HUFA) in both polar and non-polar lipids of muscle and polar fraction of liver lipids than those fed other oils. Non-polar fraction of liver lipids from all groups of turtles contained less than 1% of HUFA. All turtles contained relatively high proportions of oleic acid in their lipids regardless of the dietary lipid source. Further, lipid peroxidation in both muscle tissue and liver microsomes of turtles fed fish oil as the sole lipid source was greater (p<0.05) than those fed fish oil-free diets. Turtles fed olive oil as the sole lipid source had the lowest lipid peroxidation rate among all dietary groups. The results indicate that dietary n-3 HUFA may not be crucial for optimal growth of soft-shelled turtles although they may be used for metabolic purpose. Further, high level of dietary HUFA not only increases the HUFA content in turtle tissues, but also enhances the susceptibility of these tissues to lipid peroxidation. PMID:17137843

Lin, Way-Yee; Huang, Chen-Huei

2007-01-01

411

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

412

Annular Anionic Lipids Stabilize the Integrin ?IIb?3 Transmembrane Complex.  

PubMed

Cationic membrane-proximal amino acids determine the topology of membrane proteins by interacting with anionic lipids that are restricted to the intracellular membrane leaflet. This mechanism implies that anionic lipids interfere with electrostatic interactions of membrane proteins. The integrin ?IIb?3 transmembrane (TM) complex is stabilized by a membrane-proximal ?IIb(Arg(995))-?3(Asp(723)) interaction; here, we examine the influence of anionic lipids on this complex. Anionic lipids compete for ?IIb(Arg(995)) contacts with ?3(Asp(723)) but paradoxically do not diminish the contribution of ?IIb(Arg(995))-?3(Asp(723)) to TM complex stability. Overall, anionic lipids in annular positions stabilize the ?IIb?3 TM complex by up to 0.50 ± 0.02 kcal/mol relative to zwitterionic lipids in a headgroup structure-dependent manner. Comparatively, integrin receptor activation requires TM complex destabilization of 1.5 ± 0.2 kcal/mol, revealing a sizeable influence of lipid composition on TM complex stability. We implicate changes in lipid headgroup accessibility to small molecules (physical membrane characteristics) and specific but dynamic protein-lipid contacts in this TM helix-helix stabilization. Thus, anionic lipids in ubiquitous annular positions can benefit the stability of membrane proteins while leaving membrane-proximal electrostatic interactions intact. PMID:25632962

Schmidt, Thomas; Suk, Jae-Eun; Ye, Feng; Situ, Alan J; Mazumder, Parichita; Ginsberg, Mark H; Ulmer, Tobias S

2015-03-27

413

Composition Based Strategies for Controlling Radii in Lipid Nanotubes  

PubMed Central

Nature routinely carries out small-scale chemistry within lipid bound cells and organelles. Liposome–lipid nanotube networks are being developed by many researchers in attempt to imitate these membrane enclosed environments, with the goal to perform small-scale chemical studies. These systems are well characterized in terms of the diameter of the giant unilamellar vesicles they are constructed from and the length of the nanotubes connecting them. Here we evaluate two methods based on intrinsic curvature for adjusting the diameter of the nanotube, an aspect of the network that has not previously been controllable. This was done by altering the lipid composition of the network membrane with two different approaches. In the first, the composition of the membrane was altered via lipid incubation of exogenous lipids; either with the addition of the low intrinsic curvature lipid soy phosphatidylcholine (soy-PC) or the high intrinsic curvature lipid soy phosphatidylethanolamine (soy-PE). In the second approach, exogenous lipids were added to the total lipid composition during liposome formation. Here we show that for both lipid augmentation methods, we observed a decrease in nanotube diameter following soy-PE additions but no significant change in size following the addition of soy-PC. Our results demonstrate that the effect of soy-PE on nanotube diameter is independent of the method of addition and suggests that high curvature soy-PE molecules facilitate tube membrane curvature. PMID:24392077

Kurczy, Michael E.; Mellander, Lisa J.; Najafinobar, Neda; Cans, Ann-Sofie

2014-01-01

414

Equilibrium sampling: partitioning of organochlorine compounds from lipids into polydimethylsiloxane.  

PubMed

Polydimethylsiloxane (PDMS) can be used for equilibrium sampling of environmental pollutants in a large variety of matrices including biota. For comparison with lipid-normalized concentrations e.g. from biota monitoring programmes, reliable lipid to PDMS partition ratios (K(Lipid,PDMS)) are required. Additionally, K(Lipid,PDMS) facilitate comparison of equilibrium sampling data obtained in various environmental media and can be helpful to convert equilibrium sampling data into a more informative form. This work investigated the equilibrium partitioning of polychlorinated biphenyls (PCBs) and selected organochlorine pesticides (OCPs) between lipids from biota of different trophic levels and PDMS. One vegetable oil, a fish oil and seal oil were investigated. The lipid to PDMS partition ratios were compound-specific and ranged from 14.5 to 62.9 g/g with correction for lipid uptake into the PDMS and from 13.0 to 54.8 g/g without correction. Additionally, PDMS served as a reference partitioning phase for the accurate determination of lipid to lipid partition ratios, which for all analytes were close to unity. Evaluating the results in a bioaccumulation context, they indicate that the equilibrium partitioning of neutral lipophilic environmental contaminants into the lipids of the three investigated species will be very similar, although they represent three distinct trophic levels. PMID:18926556

Jahnke, Annika; McLachlan, Michael S; Mayer, Philipp

2008-11-01

415

Case series of lipid accumulation in the human corpus cavernosum.  

PubMed

Erectile dysfunction is a prevalent problem affecting millions of men in the United States and around the world. There have been no reports of the presence of lipids within the human penile corporal bodies, whether in normal or diseased states. We present here a case series of 9 patients who underwent penile corporal tissue biopsy during penile prosthesis insertion with severe intracorporal fibrosis and difficulties during insertion.Oil Red O staining was done to identify lipids; LipidTOX and phalloidin double staining was used to identify lipid location within the corpora, and Masson's trichrome staining was done to assess fibrosis.We identified lipid accumulation in those 9 corporal tissue samples, and further analysis showed the distribution to be 10% intramyocellular lipids and 90% extramyocellular lipids. These 9 specimens contained increased amount of collagen when compared with controls. In addition, we analyzed corporal samples from 10 random erectile dysfunction patients presenting for penile prosthesis insertion and identified no lipid accumulation in those control patients.This is the first report of lipid accumulation in the human corpus cavernosum. Possible mechanisms of lipid accumulation include androgen deficiency and dedifferentiation of corpus smooth muscle cells into other phenotypes; however, the exact mechanism is unknown and further research is needed. PMID:25674764

Alwaal, Amjad; Wang, Lin; Zaid, Uwais B; Lin, Guiting; Lue, Tom F

2015-02-01

416

Analysis of Lipoplex Structure and Lipid Phase Changes  

SciTech Connect

Efficient delivery of genetic material to cells is needed for tasks of utmost importance in the laboratory and clinic, such as gene transfection and gene silencing. Synthetic cationic lipids can be used as delivery vehicles for nucleic acids and are now considered the most promising nonviral gene carriers. They form complexes (lipoplexes) with the polyanionic nucleic acids. A critical obstacle for clinical application of the lipid-mediated DNA delivery (lipofection) is its unsatisfactory efficiency for many cell types. Understanding the mechanism of lipid-mediated DNA delivery is essential for their successful application, as well as for a rational design and synthesis of novel cationic lipoid compounds for enhanced gene delivery. A viewpoint now emerging is that the critical factor in lipid-mediated transfection is the structural evolution of lipoplexes within the cell, upon interacting and mixing with cellular lipids. In particular, recent studies showed that the phase evolution of lipoplex lipids upon interaction and mixing with membrane lipids appears to be decisive for transfection success: specifically, lamellar lipoplex formulations, which were readily susceptible to undergoing lamellar-nonlamellar phase transition upon mixing with cellular lipids and were found rather consistently associated with superior transfection potency, presumably as a result of facilitated DNA release. Thus, understanding the lipoplex structure and the phase changes upon interacting with membrane lipids is important for the successful application of the cationic lipids as gene carriers.

Koynova, Rumiana

2012-07-18

417

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

418

Nanoscale departures: excess lipid leaving the surface during supported lipid bilayer formation.  

PubMed

The behavior of small liposomes on surfaces of inorganic oxides remains enigmatic. Under appropriate conditions it results in the formation of supported lipid bilayers (SLBs). During this process, some lipids leave the surface (desorb). We were able to visualize this by a combination of time-resolved fluorescence microscopy and fluorescence recovery after photobleaching studies. Our observations also allowed us to analyze the kinetics of bilayer patch growth during the late stages of SLB formation. We found that it entails a balance between desorption of excess lipids and further adsorption of liposomes from solution. These studies were performed with liposomes containing zwitterionic phospholipids (dioleoylphosphatidylcholine alone or a mixture of dioleoylphosphatidylcholine, dipalmitoylphosphatidylcholine, and cholesterol) on TiO2 in the presence of Ca(2+) but in the absence of other salts. PMID:24266399

Zhu, Ling; Gregurec, Danijela; Reviakine, Ilya

2013-12-10

419

Lipid abnormalities and lipid-based repair strategies in atopic dermatitis.  

PubMed

Prior studies have revealed the key roles played by Th1/Th2 cell dysregulation, IgE production, mast cell hyperactivity, and dendritic cell signaling in the evolution of the chronic, pruritic, inflammatory dermatosis that characterizes atopic dermatitis (AD). We review here increasing evidence that the inflammation in AD results primarily from inherited abnormalities in epidermal structural and enzymatic proteins that impact permeability barrier function. We also will show that the barrier defect can be attributed to a paracellular abnormality due to a variety of abnormalities in lipid composition, transport and extracellular organization. Accordingly, we also review the therapeutic implications of this emerging pathogenic paradigm, including several current and potentially novel, lipid-based approaches to corrective therapy. This article is part of a Special Issue entitled The Important Role of Lipids in the Epidermis and their Role in the Formation and Maintenance of the Cutaneous Barrier. Guest Editors: Kenneth R. Feingold and Peter Elias. PMID:24128970

Elias, Peter M

2014-03-01

420

Chitosan as a lipid binder: a langmuir monolayer study of chitosan-lipid interactions.  

PubMed

Owing to its distinct chemico-biological properties, chitosan, a cationic biopolymer, offers a great potential in multifarious bioapplications. One such application is as a dietary antilipidemic supplement to be used to reduce obesity/overweight and to lower cholesterol. The lipid-binding efficiency of chitosan, however, remains debatable. Accordingly, in this study we investigated the interactions of chitosan with selected lipids, cholesterol and fatty acids, the latter including saturated (stearic acid) and unsaturated (oleic, linoleic, alpha-linolenic) acids. The experiments were performed with the Langmuir monolayer technique, in which surface pressure-area isotherms were recorded for the lipid monolayers spread on the acetate buffer pH 4.0 subphase in the absence and presence of chitosan. We found that the presence of chitosan in the subphase strongly influenced the shape and location of the isotherms, proving that there existed attractions between chitosan and lipid molecules. The attractions were revealed by changes of the molecular organization of the monolayers. The common feature of these changes was that all the monolayers studied underwent expansion, in each case reaching saturation with increasing chitosan concentration. In agreement with the lipid molecular structures, the highest expansions were observed for the most unsaturated fatty acids, linoleic and alpha-linolenic, the lowest for stearic acid, with oleic acid and cholesterol being the intermediate cases. By contrast, the main distinguishing feature of these changes was that, although none of the monolayers studied changed its state when completely saturated with chitosan, compared to the parent ones the compactness of the monolayers was modified. The solid monolayers of stearic acid and cholesterol were loosened, whereas those of all the unsaturated acids, liquid in nature, were tightened. On the basis of these results we tentatively propose a mechanism of the chitosan action that includes both electrostatic and hydrophobic lipid-chitosan interactions as well as hydrogen bonding between them. PMID:17630796

Wydro, Pawe?; Krajewska, Barbara; Hac-Wydro, Katarzyna

2007-08-01

421

Simplification of analyses of fatty acids in fish lipids and related lipid samples.  

PubMed

The longer chain, highly unsaturated fatty acids up to 22:6 and typical of fish lipids must be included in many current analyses of fatty acids of diets, blood, and eventually of organ lipids. The use of the GLC liquid phase Carbowax-20M in a bonded, or cross-linked form, wall-coated in glass or flexible fused silica capillary columns, eliminates the confusing overlap of component fatty acids of different chain lengths found with polar packed GLC columns. Either isothermal or programmed conditions yield comparable results illustrated with a fish oil analysis. PMID:3314363

Ackman, R G

1987-01-01

422

Characterization of Horizontal Lipid Bilayers as a Model System to Study Lipid Phase Separation  

PubMed Central

Abstract Artificial lipid membranes are widely used as a model system to study single ion channel activity using electrophysiological techniques. In this study, we characterize the properties of the artificial bilayer system with respect to its dynamics of lipid phase separation using single-molecule fluorescence fluctuation and electrophysiological techniques. We determined the rotational motions of fluorescently labeled lipids on the nanosecond timescale using confocal time-resolved anisotropy to probe the microscopic viscosity of the membrane. Simultaneously, long-range mobility was investigated by the lateral diffusion of the lipids using fluorescence correlation spectroscopy. Depending on the solvent used for membrane preparation, lateral diffusion coefficients in the range Dlat = 10–25 ?m2/s and rotational diffusion coefficients ranging from Drot = 2.8 ? 1.4 × 107 s?1 were measured in pure liquid-disordered (Ld) membranes. In ternary mixtures containing saturated and unsaturated phospholipids and cholesterol, liquid-ordered (Lo) domains segregated from the Ld phase at 23°C. The lateral mobility of lipids in Lo domains was around eightfold lower compared to those in the Ld phase, whereas the rotational mobility decreased by a factor of 1.5. Burst-integrated steady-state anisotropy histograms, as well as anisotropy imaging, were used to visualize the rotational mobility of lipid probes in phase-separated bilayers. These experiments and fluorescence correlation spectroscopy measurements at different focal diameters indicated a heterogeneous microenvironment in the Lo phase. Finally, we demonstrate the potential of the optoelectro setup to study the influence of lipid domains on the electrophysiological properties of ion channels. We found that the electrophysiological activity of gramicidin A (gA), a well-characterized ion-channel-forming peptide, was related to lipid-domain partitioning. During liquid-liquid phase separation, gA was largely excluded from Lo domains. Simultaneously, the number of electrically active gA dimers increased due to the increased surface density of gA in the Ld phase. PMID:20550901

Honigmann, Alf; Walter, Claudius; Erdmann, Frank; Eggeling, Christian; Wagner, Richard

2010-01-01

423

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

424

Systems-Level Lipid Analysis Methodologies for Qualitative and Quantitative Investigation of Lipid Signaling Events During Wound Healing  

PubMed Central

Objective Accumulating evidence implicates a prominent role for lipid signaling molecules in the regulation of wound healing. These lipids regulate hemostasis, onset and resolution of inflammation, migration and proliferation cells, angiogenesis, epithelialization, and remodeling of collagen. The objective of this overview is to demonstrate the applicability of systems level lipid analyses to identify and quantify lipid involved in events leading to wound healing. Approach Current advances in liquid chromatography coupled to tandem mass spectrometry have provided the means for carrying out quantitative and qualitative analysis of lipids at a systems level. This emerging field is collectively referred to as lipidomics and its potential in wound healing research is largely ignored. Results While comprehensive applications of lipidomics in wound healing are limited, studies carried out by the authors as well as others demonstrate distinct changes in the lipidome during the wound healing process. Innovation Until recently, investigations into lipids were limited to the study of a few lipids at a time. Lipidomics approaches provide the capability to quantitatively and qualitatively assay almost the full complement of lipid signaling circuits at the same time. This allows obtaining a system level understanding of changes to the entire lipidome during the wound healing process. Conclusion The technology provides promising approach to understanding new signaling pathways based on lipids involved in wound healing. The understanding gained from such studies has the potential for the development of novel lipid based treatment strategies to promote wound healing. PMID:24527363

Wijesinghe, Dayanjan S.; Chalfant, Charles E.

2013-01-01

425

Microbial lipid-based lignocellulosic biorefinery: feasibility and challenges.  

PubMed

Although single-cell oil (SCO) has been studied for decades, lipid production from lignocellulosic biomass has received substantial attention only in recent years as biofuel research moves toward producing drop-in fuels. This review gives an overview of the feasibility and challenges that exist in realizing microbial lipid production from lignocellulosic biomass in a biorefinery. The aspects covered here include biorefinery technologies, the microbial oil market, oleaginous microbes, lipid accumulation metabolism, strain development, process configurations, lignocellulosic lipid production, technical hurdles, lipid recovery, and technoeconomics. The lignocellulosic SCO-based biorefinery will be feasible only if a combination of low- and high-value lipids are coproduced, while lignin and protein are upgraded to high-value products. PMID:25483049

Jin, Mingjie; Slininger, Patricia J; Dien, Bruce S; Waghmode, Suresh; Moser, Bryan R; Orjuela, Andrea; Sousa, Leonardo da Costa; Balan, Venkatesh

2015-01-01

426

Binding of local anaesthetics to the lipid emulsion Clinoleic™ 20%.  

PubMed

Lipid emulsions have been used to treat cardiovascular collapse due to local anaesthetic toxicity. However, there are few data available on the comparative efficiency of the partitioning properties of available lipid emulsions in clinical use. This in vitro study compared the buffering properties of the lipid emulsions Clinoleic™ 20% (Baxter, Old Toongabbie, NSW) and Intralipid® 20% (Fresenius Kabi, Pymble, NSW) using both bupivacaine (Marcain® 0.5%, AstraZeneca, North Ryde, NSW) and ropivacaine (Naropin® 1%, AstraZeneca, North Ryde, NSW). The concentration of anaesthetic in buffer before and after mixing with lipid was quantified using chromatographic analysis. Bupivacaine was more effectively bound by the lipid agents, with a 40% reduction in initial concentration. Ropivacaine demonstrated a 20% reduction in concentration with the addition of lipid agents. Importantly, there was no significant difference between Intralipid and Clinoleic in terms of their buffering behaviour, suggesting equivalent binding efficacy. PMID:23977913

Evans, J A; Wallis, S C; Dulhunty, J M; Pang, G

2013-09-01

427

Applications of Mass Spectrometry to Lipids and Membranes  

PubMed Central

Lipidomics, a major part of metabolomics, constitutes the detailed analysis and global characterization, both spatial and temporal, of the structure and function of lipids (the lipidome) within a living system. As with proteomics, mass spectrometry has earned a central analytical role in lipidomics, and this role will continue to grow with technological developments. Currently, there exist two mass spectrometry-based lipidomics approaches, one based on a division of lipids into categories and classes prior to analysis, the “comprehensive lipidomics analysis by separation simplification” (CLASS), and the other in which all lipid species are analyzed together without prior separation, shotgun. In exploring the lipidome of various living systems, novel lipids are being discovered, and mass spectrometry is helping characterize their chemical structure. Deuterium exchange mass spectrometry (DXMS) is being used to investigate the association of lipids and membranes with proteins and enzymes, and imaging mass spectrometry (IMS) is being applied to the in situ analysis of lipids in tissues. PMID:21469951

Harkewicz, Richard; Dennis, Edward A.

2012-01-01

428

Insect endosymbiont proliferation is limited by lipid availability  

PubMed Central

Spiroplasma poulsonii is a maternally transmitted bacterial endosymbiont that is naturally associated with Drosophila melanogaster. S. poulsonii resides extracellularly in the hemolymph, where it must acquire metabolites to sustain proliferation. In this study, we find that Spiroplasma proliferation specifically depletes host hemolymph diacylglyceride, the major lipid class transported by the lipoprotein, Lpp. RNAi-mediated knockdown of Lpp expression, which reduces the amount of circulating lipids, inhibits Spiroplasma proliferation demonstrating that bacterial proliferation requires hemolymph-lipids. Altogether, our study shows that an insect endosymbiont acquires specific lipidic metabolites from the transport lipoproteins in the hemolymph of its host. In addition, we show that the proliferation of this endosymbiont is limited by the availability of hemolymph lipids. This feature could limit endosymbiont over-proliferation under conditions of host nutrient limitation as lipid availability is strongly influenced by the nutritional state. DOI: http://dx.doi.org/10.7554/eLife.02964.001 PMID:25027439

Herren, Jeremy K; Paredes, Juan C; Schüpfer, Fanny; Arafah, Karim; Bulet, Philippe; Lemaitre, Bruno

2014-01-01

429

Effect of internal wool lipid liposomes on skin repair.  

PubMed

Intercellular lipids of the stratum corneum (SC) play a crucial role in keeping an optimal skin barrier function and in regulating the water-holding capacity. Recently, the internal lipids have been extracted from wool fibre. This lipid extract has a composition similar to that of the SC lipids. Two parameters were used to test the effect of topically applied internal wool lipids (IWL), structured as liposomes, on the water barrier functions of disturbed and intact skin: transepidermal water loss and skin capacitance. Liposomes made up of lipids that simulate the composition of the SC were also applied for comparison. The single application of the IWL liposomes on disturbed skin resulted in an accelerated recovery of water barrier functions. Daily application of these liposomes on intact skin for 5 days reinforced the skin barrier and increased the water-holding capacity. The repairing effect of the IWL enhances their suitability in the treatment, prevention and care of skin. PMID:10859538

de Pera, M; Coderch, L; Fonollosa, J; de la Maza, A; Parra, J L

2000-01-01

430

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

431

INFLAMMATION AND LIPID SIGNALING IN THE ETIOLOGY OF INSULIN RESISTANCE  

PubMed Central

Inflammation and lipid signaling are intertwined modulators of homeostasis and immunity. In addition to the extensively studied eicosanoids and inositol phospholipids, emerging studies indicate that many other lipid species act to positively and negatively regulate inflammatory responses. Conversely inflammatory signaling can significantly alter lipid metabolism in the liver, adipose tissue, skeletal muscle and macrophage in the context of infection, diabetes and atherosclerosis. Here, we review recent findings related to this interconnected network from the perspective of immunity and metabolic disease. PMID:22560216

Glass, Christopher K.; Olefsky, Jerrold M.

2014-01-01

432

Complex lipid biosynthesis and its manipulation in plants  

Microsoft Academic Search

In all living organisms lipids play several roles and, according to their structures, can be divided into two main groups:\\u000a the non-polar lipids (acylglycerols, sterols, free fatty acids, wax and steryl esters) and polar lipids (phosphoglycerides,\\u000a glycosylglycerides, and sphingolipids). Triacylglycerols act as compact, easily metabolised and non-hydrated energy stores.\\u000a They are important storage products especially in plants producing oilseeds and

Irina A. Guschina; John L. Harwood

433

A membrane capture assay for lipid kinase activity  

Microsoft Academic Search

Phosphoinositide kinases such as PI3-kinase synthesize lipid second messengers that control diverse cellular processes. Recently, these enzymes have emerged as an important class of drug targets, and there is significant interest in discovering new lipid kinase inhibitors. We describe here a procedure for the high-throughput determination of lipid kinase inhibitor IC50 values. This assay exploits the fact that phosphoinositides, but

Zachary A Knight; Morri E Feldman; Andras Balla; Tamas Balla; Kevan M Shokat

2007-01-01

434

Metal-catalyzed oxidation in mackerel skin and meat lipids  

Microsoft Academic Search

Kinetic effects of added copper, zinc, and iron compounds have been investigated in the oxidation of lipids in mackerel skin\\u000a and meat at 60 C using a simple weight gain method. Inorganic Fe(II) and Cu(II) were found to be strong catalysts in mackerel\\u000a lipid oxidation. The meat lipids were particularly sensitive to oxidation in the presence of Fe(II) and Cu(II)

P. J. Ke; R. G. Ackman

1976-01-01

435

Biogenesis and function of the lipidic structures of pollen grains  

Microsoft Academic Search

Pollen grains contain several lipidic structures, which play a key role in their development as male gametophytes. The elaborate\\u000a extracellular pollen wall, the exine, is largely formed from acyl lipid and phenylpropanoid precursors, which together form\\u000a the exceptionally stable biopolymer sporopollenin. An additional extracellular lipidic matrix, the pollen coat, which is particularly\\u000a prominent in entomophilous plants, covers the interstices of

Pietro Piffanelli; Joanne H. E. Ross; D. J. Murphy

1998-01-01

436

Intersection of the unfolded protein response and hepatic lipid metabolism  

Microsoft Academic Search

The liver plays a central role in whole-body lipid metabolism by governing the synthesis, oxidization, transport and excretion\\u000a of lipids. The unfolded protein response (UPR) was identified as a signal transduction system that is activated by ER stress.\\u000a Recent studies revealed a critical role of the UPR in hepatic lipid metabolism. The IRE1\\/XBP1 branch of the UPR is activated\\u000a by

Ann-Hwee Lee; Laurie H. Glimcher

2009-01-01

437

Nonequilibrium Behavior in Supported Lipid Membranes Containing Cholesterol  

Microsoft Academic Search

We investigate lateral organization of lipid domains in vesicles versus supported membranes and monolayers. The lipid mixtures used are predominantly DOPC\\/DPPC\\/Chol and DOPC\\/BSM\\/Chol, which have been previously shown to produce coexisting liquid phases in vesicles and monolayers. In a monolayer at an air-water interface, these lipids have miscibility transition pressures of ?12–15mN\\/m, which can rise to 32mN\\/m if the monolayer

Benjamin L. Stottrup; Sarah L. Veatch; Sarah L. Keller

2004-01-01

438

Effect of storage on lipids of fish protein concentrate  

Microsoft Academic Search

Fish protein concentrates (FPC) made from pout, alewife and Gulf menhaden were stored for 6 months at temperatures of 37 C\\u000a and 50 C with no attempt to control humidity. When the amount of extractable lipid was 0.1% or less there were small changes\\u000a in the lipid pattern: a small decrease in the amount of neutral lipid-free fatty acid fraction

Barbara Medwadowski; Alleah Haley; John van der Veen; H. S. Olcott

1971-01-01

439

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

440

Identification of some new minor acids from chicken skin lipids.  

PubMed

Lipids from the skin of commercially processed broilers were extracted by Folch's technique and analyzed for fatty acids as their methyl esters by gas-liquid chromatography/mass pectrometry. Of the 24 fatty acids, identified, 5 had not been previously identified in either total chicken skin lipids or skin lipid fractions. They are: pentadecenoic acid (15:1), heptadecenoic acid (17:1), arachidic acid (20:0), heneicosanoic acid (21:0), and erucic acid (22:1). PMID:674060

Horvat, R J

1978-05-01

441

Regulation of Plant Transporters by Lipids and Microdomains  

Microsoft Academic Search

\\u000a Transporters in the broad sense, that is, carriers, pumps, and channels, are proteins inserted in a lipid bilayer separating\\u000a two cellular compartments. This lipid bilayer is not only the physical support of such proteins, but also a powerful way to\\u000a regulate their activity. This chapter will first summarize the different means by which lipids c