Adaptive modification of membrane lipids in Tetrahymena pyriformis during starvation. Alterations in phospholipid composition and positional distribution of fatty acyl chains.
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Animals↗
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[Modification of the lipid profile of human placenta by moderate maternal undernutrition].
The lipid composition of human placenta phospholipids, coming from 9 undernourished women that gave birth to low weight newborns and 9 well nourished women, was analyzed using gas-liquid chromatography. Phospholipids of placentas coming from undernourished women, when compared to well nourished women, had significantly lower amounts of w-6 and w-3 fatty acids (40.1 +/- 1.5 vs 42.4 +/- 1.4 and 6.0 +/- 0.7 vs 7.1 +/- 1.3% respectively). The calculated mean melting point was higher in plancetas coming from undernourished women. It these women, the low content of polyunsaturated fatty acids and its replacement by short chain fatty acids was not able to balance the high mean melting points. The relative deficiency of essential fatty acids, the low saturation index and the high mean melting point of undernourished women's placental phospholipids, may suggest a lower membrane fluidity and a subnormal essential fatty acid content of fetal organs, that are essential for normal growth and development.
Analysis of Variance↗
[Adaptive modification of lipid-protein structure of membranes during exposure to climatic-geophysical factors of high-altitude].
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Acclimatization↗
Modification of the lipid component modulates nuclear matrix nucleolytic activity.
It was shown that lipid composition of plant nuclear matrix depends on procedure of its isolation. The matrix isolated with the use of lithium diiodosalicylate (LiS) differs in its lipid composition from the preparation isolated with the use of nonionic detergent (Triton X-100). It was also shown that the nucleolytic activity of the matrix is related to its lipid component. Matrix depleted in lipids loses half of its nucleolytic activity which is recovered after supplementation with previously extracted lipids. The extent of recovery of the nucleolytic activity is also dependent on the presence of residual DNA in matrix preparation. The recoveries of nucleolytic activities were higher in matrices not depleted in their DNA content.
Iodobenzoates↗
Free radical induced biophysical modification of membrane lipids: a novel mechanism proposed for a haemorheological alteration induced by 4,5' 8-trimethyl psoralen.
Haemostasis is the spontaneous arrest of bleeding from damaged blood vessel. Platelet aggregation is the major event in this process. A number of drugs are known to inhibit this process of platelet aggregation. 4,5' 8-trimethyl psoralen a naturally occurring furocoumarin is used as a photochemotherapeutic agent in PUVA therapy. It shows antithrombotic action by preventing platelet aggregation induced by adenosine diphosphate in vitro. It is proposed that a free radical induces a lipid phase transition of the membrane lipids, the platelet membrane undergoes certain biophysical alteration leading to increased membrane fluidity resulting in a loss of aggregating ability.
Adult↗
[Study by NMR of the modifications of brain lipid composition related to the tumor processes].
1H, 13C, 31P and 14N NMR spectroscopies were used to investigate the lipid composition of brain tumors (GL6 glioma) in rats, by comparison with controlateral hemispheres. Comparative indexes derived from NMR signal intensities were used to establish the statistical analysis. It was found that sterol metabolism and sphingolipid/glycerolipids ratio are significantly modified when a tumor is present.
Animals↗
[Role of GABA in the modulation of Na, K-pump activity in nerve cells after irradiation and experimental modification of membrane lipid component].
After irradiation acute (12 Gy, 600 mGy/min), single prolonged (0.25 Gy, 1.75 mG/min), chronic (0.01 Gy/day, 0.25 Gy, 0.50 Gy, 1.75 mGy/min), and experimental disturbances of cell membranes with phospholipases-A2, -D, and arachidonic acid administration the considerable changes in Na,K-pump function were found in rat brain cortex slices, with their reduction almost to the control level in presence of gamma-aminobutyric acid (0.1-10.0 mcM). It had been supposed existing of the GABA-ergic "homeostasis control" mechanism, which restores the intracellular potassium homeostasis via GABA-modulation of the Na,K-pump activity by principles of receptor-mediated structural-membrane regulation under extreme factor influence.
Animals↗
[Somatometry and lipid profile in smokers. Modifications after smoking withdrawal].
BACKGROUND: The purpose of this work was to determine the somatometric and lipidic profile in a group of 90 smokers and to carry out a prospective study on modifications due to smoking withdrawal. METHODS: A somatometric and lipidic profile was performed to 90 smokers and 30 non-smokers. Afterwards smokers were included in a smoking withdrawal program. One year later all subjects who stopped smoking as well as 10 of the smokers who failed in smoking withdrawal underwent a new blood analysis and somatometric study. RESULTS: Initial somatometry showed that smokers had a significantly higher (p less than 0.05) overweight and endomorphic index, based on somatometric characteristics. In addition, smokers showed significant lower level of HDL-cholesterol (high-density lipoprotein) than non-smokers (p less than 0.001). Somatometric and lipidic profile performed one year after smoking cessation showed a statistically significant increase on HDL-cholesterol (p less than 0.05). Somatometric and lipidic profile of the subjects who failed in smoking withdrawal showed no significant changes in relation to the study made the previous year. CONCLUSIONS: From these data we suggest that modifications of lipidic profile induced by tobacco consumption can be reverted, at least in part, after smoking cessation. In addition smokers present higher overweight when theoretic weight is based on somatometric characteristics.
Adult↗
[Lipid dependence of cytochrome P-450 activity in rat liver microsomes using lipid exchange proteins].
Modification of membrane lipid composition by lipid exchange proteins was used to study the lipid dependence of cytochrome P-450 activity in rat liver microsomes. The introduction of exogenous lysophosphatidylcholine into microsomal membranes decreased the capacity of cytochrome P-450 to demethylate dimethylaniline and dimethylaminoantipyrine and to hydroxylate aniline. A subsequent introduction of phosphatidylcholine resulted in an almost complete reactivation of the enzyme.
Animals↗
Chemical and photochemical modification of colicin E1 and gramicidin A in bilayer lipid membranes.
Chemical modification and photodynamic treatment of the colicin E1 channel-forming domain (P178) in vesicular and planar bilayer lipid membranes (BLMs) was used to elucidate the role of tryptophan residues in colicin E1 channel activity. Modification of colicin tryptophan residues by N-bromosuccinimide (NBS), as judged by the loss of tryptophan fluorescence, resulted in complete suppression of wild-type P178 channel activity in BLMs formed from fully saturated (diphytanoyl) phospholipids, both at the macroscopic-current and single-channel levels. The similar effect on both the tryptophan fluorescence and the electric current across BLM was observed also after NBS treatment of gramicidin channels. Of the single-tryptophan P178 mutants studied, W460 showed the highest sensitivity to NBS treatment, pointing to the importance of the water-exposed Trp460 in colicin channel activity. In line with previous work, the photodynamic treatment (illumination with visible light in the presence of a photosensitizer) led to suppression of P178 channel activity in diphytanoyl-phospholipid membranes concomitant with the damage to tryptophan residues detected here by a decrease in tryptophan fluorescence. The present work revealed novel effects: activation of P178 channels as a result of both NBS and photodynamic treatments was observed with BLMs formed from unsaturated (dioleoyl) phospholipids. These phenomena are ascribed to the effect of oxidative modification of double-bond-containing lipids on P178 channel formation. The pronounced stimulation of the colicin-mediated ionic current observed after both pretreatment with NBS and sensitized photomodification of the BLMs support the idea that distortion of membrane structure can facilitate channel formation.
Bromosuccinimide↗
Lipid peroxidation and protein modification in a mouse model of chronic iron overload.
Iron-storage diseases are believed to cause organ damage through generation of reactive oxygen species. Using a murine model of iron overload, we found that hepatic iron stores increased logarithmically during 3 weeks of chronic intraperitoneal administration of iron dextran, while hepatic glutathione peroxidase activity declined linearly by approximately 50% during the same period. Plasma concentrations of aliphatic aldehydes increased by 2- to 3-fold, and plasma malondialdehyde (MDA) by 6-fold. Modification of total liver protein by products of lipid peroxidation, including MDA-lysine, 4-hydroxynonenal-lysine, and N(epsilon)-(carboxymethyl)lysine (CML), increased by approximately 3-fold, while levels of the protein oxidation marker, methionine sulfoxide (MetSO), were unchanged. Skin collagen was resistant to modification until the third week, when 2- to 3-fold increases in both CML and MetSO were observed. Our results document that iron overload increases lipid peroxidation, with concomitant increases in reactive aldehydes in plasma and chemical modification of tissue proteins. CML was a sensitive indicator of hepatocellular oxidative stress, compared to MetSO, while extensive modification of extracellular skin collagen was not observed until the late stages of iron overload and oxidative stress. These observations provide direct evidence for the contribution of reactive oxygen species, lipid peroxidation, and reactive carbonyl intermediates to the pathogenesis of iron-overload diseases.
Aldehydes↗
[Lipid peroxidation and LDL modifications in nondiabetic patients with ischemic heart disease: the role of insulin action].
BACKGROUND: Nondiabetic patients with advanced coronary artery disease (CAD) were assessed for lipid peroxidation, LDL modifications and insulin action. Twenty-four patients and 10 normal controls were studied. METHODS: Insulin tolerance test (Kitt), glucose, insulin lipoproteins, electronegatively charged, modified, low density lipoproteins (LDL-) and the thiobarbituric acid reactivity (TBARS), as an index of lipid peroxidation, were determined. RESULTS: No difference was observed in insulin action (determined by insulin tolerance test) between patients with CAD (3.31 +/- 0.28%/min; range 0.73-6.13) and normal controls (3.59 +/- 0.42; range 1.76-6.06). The percentage of modified, electronegative LDL (LDL -) was higher in patients with CAD (0.5 +/- 0.48%; range 1.3-9.2) than that of controls (2.80 +/- 0.33; range 1.00-4.00; p = 0.013). TBARS were significantly (P = 0.043) higher in CAD patients (3.49 +/- 0.17 nmol/ml; range 2.4-5.5) than normal controls (1.47 +/- 0.12; range 1.07-2.10). A significantly negative correlation was observed between Kitt and TBARS (r= - 0.48; p = 0.016), and a significant (r = 0.46; p = 0.022) positive correlation was observed between plasma glucose and TBARS. On the contrary no correlation has been observed between LDL- and TBARS. CONCLUSIONS: We conclude that in patients with advanced coronary artery disease: A) there are increased circulating levels of modified low density lipoprotein; B) there is evidence of increased lipid peroxidation. This latter process is significantly influenced by the degree of insulin action.
Blood Glucose↗
Fatty acid metabolism in L1210 murine leukemia cells: differences in modification of fatty acids incorporated into various lipids.
L1210 leukemia cells can utilize all of the main fatty acids that normally are present in the ascites fluid in which they grow. This finding is consistent with the view that L1210 cells derive most of their fatty acids from the ascites fluid. From 80--90% of each fatty acid was incorporated into cell lipids without structural modification, suggesting that the lipid composition of these cells can be altered by changing the type of fatty acids to which they are exposed. Most importantly, the palmitate that was subsequently incorporated into total cell phospholipids was elongated and desaturated somewhat more than that incorporated into triglycerides. This difference was due primarily to more extensive modification of the palmitate incorporated into the ethanolamine phosphoglycerides fraction. Although there was no difference between total phospholipids and triglycerides with linoleate, more of the linoleate incorporated into ethanolamine phosphoglycerides was elongated and further desaturated than that incorporated into choline phosphoglycerides and triglycerides. These findings indicate fatty acids incorporated into various cell lipid fractions are not structurally modified to the same extent. There appears to be greater modification of fatty acid used for ethanolamine phosphoglyceride synthesis as compared with triglyceride and choline phosphoglyceride synthesis.
Animals↗
Barley lipid transfer protein, LTP1, contains a new type of lipid-like post-translational modification.
In plants a group of proteins termed nonspecific lipid transfer proteins are found. These proteins bind and catalyze transfer of lipids in vitro, but their in vivo function is unknown. They have been suggested to be involved in different aspects of plant physiology and cell biology, including the formation of cutin and involvement in stress and pathogen responses, but there is yet no direct demonstration of an in vivo function. We have found and characterized a novel post-translational modification of the barley nonspecific lipid transfer protein, LTP1. The protein-modification bond is of a new type in which an aspartic acid in LTP1 is bound to the modification through what most likely is an ester bond. The chemical structure of the modification has been characterized by means of two-dimensional homo- and heteronuclear nuclear magnetic resonance spectroscopy as well as mass spectrometry and is found to be lipid-like in nature. The modification does not resemble any standard lipid post-translational modification but is similar to a compound with known antimicrobial activity.
Amino Acids↗
Hydroxyl radical-induced decline in motility and increase in lipid peroxidation and DNA modification in human sperm.
We employed the xanthine-xanthine oxidase system to produce H2O2 or simply used commercially available H2O2 solution to investigate the effects of exogenous hydroxyl radicals on the motility characteristics and on lipid peroxidation and DNA modification of human sperm. The functional parameters of sperm motility declined concomitantly upon incubation of sperm with hydroxyl radicals. After incubation of freshly ejaculated human sperm with 0.23 mM H2O2 in the presence of 1.8 mM ADP and 2.7 mM FeSO4 for 1 hr at 37 degrees C, 90% reduction of motility was observed. Effect of hydroxyl radicals on sperm motility was dependent on the concentrations of FeSO4 and H2O2, respectively. The remaining motility of sperm after 1 hr incubation showed negative linear correlation with FeSO4 concentration. The response of sperm motility to FeSO4 was also dependent on the concentration of H2O2. Except for the amplitude of lateral head displacement, functional parameters of sperm declined with the increase of H2O2 concentration. Moreover, we found that lipid peroxidation measured as malondialdehyde (MDA) and accumulation of modified DNA indicated by 8-hydroxy-2'-deoxyguanosine (8-OH-dG) in human sperm were significantly accelerated by exogenous hydroxyl radicals. The contents of lipid peroxides and 8-OH-dG in the spermatozoa were increased from 24.6 +/- 2.4 nmol MDA/1 x 10(7) sperm and 0.17 +/- 0.02% in the untreated group to 30.6 +/- 1.2 nmol MDA/1 x 10(7) sperm and 1.9 +/- 0.47%, respectively, in the sperm treated at 37 degrees C for 1 hr with 2.03 mM H2O2, 1.8 mM ADP and 4.5 mM FeSO4. Taken together, these results suggest that the detrimental effects of hydroxyl radicals on human sperm functions may be mediated, at least partly, through lipid peroxidation and DNA modification.
8-Hydroxy-2'-Deoxyguanosine↗
Fusion of negatively charged phospholipid vesicles by insulin. Relationship with lipid fluidity.
We have studied, by fluorescence methods, the association of insulin to liposomes, the modification of lipid fluidity, and the fusion of vesicles induced by insulin. All parameters showed a similar dependence on pH and ionic strength of the medium and on negative charges in liposomes. The influence of temperature indicated that the association of insulin to liposomes per se was not sufficient to produce a decrease in lipid fluidity and fusion of liposomes. The modification of lipid fluidity induced by insulin in biological membranes is discussed as a possible general event in the action of the hormone.
Fluorescamine↗
Lipid peroxidation in low density lipoproteins from human plasma and egg yolk promotes accumulation of 1-acyl analogues of platelet-activating factor-like lipids.
Oxidative modification of low density lipoprotein (LDL) is known to be a key event for induction of atherosclerosis. However, there has been little progress in structural elucidation of oxidized lipids, especially oxidatively fragmented phospholipids retaining a glycerol backbone. In this study, we found that LDL derived from egg yolk has no platelet-activating factor (PAF) acetylhydrolase activity, and that prolonged incubation of egg yolk LDL with Cu2+ resulted in the formation of various PAF-like lipids: 1-acyl type phosphatidylcholines with an sn-2-short-chain dicarboxylate or monocarboxylate group. Only a very small amount of the PAF-like lipid having an sn-2-short-chain monocarboxylate group was detected by gas chromatography-mass spectrometry in Cu(2+)-oxidized LDL from human plasma with high PAF-acetylhydrolase activity, which has been reported to hydrolyze PAF-like lipids to lysophosphatidyl-cholines. Preincubation of plasma LDL with diisopropyl fluorophosphate dose-dependently inhibited PAF-acetylhydrolase activity, resulting in accumulation of the PAF-like lipids when the LDL was oxidized with Cu2+. As well as PAF and lysophosphatidylcholines, several PAF-like lipids were found to inhibit [3H]thymidine incorporation into cultured vascular smooth muscle cells derived from rat aorta. The possible formation of PAF-like lipids by lipid peroxidation in LDL is discussed as well as its possible significance for induction of atherosclerosis.
Acylation↗
Synthesis of novel cationic lipids: effect of structural modification on the efficiency of gene transfer.
A series of novel cationic lipids was designed and synthesized in an effort to understand the importance of the various structural features with respect to transfection efficiency. Particular attention has been paid to the hydrophobic domain and the cationic headgroup. An efficient method of synthesizing asymmetric diether lipids is described, using alkyl chains ranging from C(12) to C(18) and the unsaturated oleyl group. The ternary formulations including the diether lipid 3beta-[N-(N',N'-dimethylaminoethyl)carbamoyl]cholesterol (DC-Chol) and dioleoyl phosphatidylethanolamine (DOPE) were up to 10-fold more efficacious in in vitro assays than the DC-Chol/DOPE control. The shorter and most asymmetric diether lipids performed the best. The chemical nature and basicity of the headgroups have been varied by the coupling of the four naturally occurring amino acids with cationic side chains-arginine, histidine, lysine, and tryptophan. Transfection efficiency was highest for arginine/lysine derivatives, with binary formulations containing the amino acid derivative alone and DOPE proving superior.
Animals↗