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At least 919 records · Page 51Linked to original sources
PubMed1998

Lipid and cell membranes in the presence of gadolinium and other ions with high affinity to lipids. 2. A dipole component of the boundary potential on membranes with different surface charge.

When Gd3+, a trivalent lanthanide, binds phospholipids with a high affinity, it elicits strong electrostatic effects on the surface of the lipid bilayer. Two experimental methods were applied to monitor the changes in the boundary and surface potentials induced by Gd3+ adsorption on liposomes and planar lipid bilayer membranes (BLM) made from phosphatidylserine (PS), phosphatidylcholine (PC) and their mixtures. The membrane surface charge density was changed by either varying the PS/PC ratio or by changing the degree of PS headgroup ionization in the range of pH between 2.5 and 7.5. The Gouy-Chapman-Stern (GCS) theory combined with the condition of mass balance in the experimental cell was used for quantitative treatment of ion adsorption and related changes in the diffuse part of the electrical double layer (surface potential). Data obtained using microelectrophoresis of liposome suspensions were well described within the framework of the modified GCS theory with constants of 5.10(4) and 10(3) M-1 for Gd3+ association with PS and PC, respectively (Yu. A. Ermakov, A. Z. Averbakh, and S. I. Sukharev, Biol. Membrany 14:434-445 (1997) (in Russian)). The intramembrane field compensation (IFC) technique used to study Gd3+ adsorption on planar lipid bilayers by monitoring the entire boundary potential gave completely different results. An observed drastic difference (approximately 140 mV) between the changes of boundary and surface potential was interpreted as the change in the dipole potential induced by binding of Gd3+. The magnitude of the surface dipole increased with the concentration of PS in PS/PC mixtures and became significant at most negative surface charges (more than 80% of PS in the mixture) and strongly correlated with the degree of PS ionization at different pH. The nature of structural changes at the membrane/water interface induced by Gd(3+)-PS interaction and possible lipid clusterization are discussed in the context of their biological importance.

Adsorption↗
PubMedDate not supplied

[The effect of anesthesia on lipid peroxidation, the antioxidant system and lipid metabolism during cesarean section in parturients with severe forms of late gestosis].

Forty-three parturients with severe late gestosis were subjected to cesarean section under endotracheal general anesthesia (EGA) (23 pts) and combined epidural anesthesia (CEA) (20 pts). Lipid peroxidation (LPO), antioxidant system (AOS), and lipid metabolism parameters were evaluated at various stages of anesthesia and operation. EN involved a marked increase in LPO, suppressed the activities of vitamin and enzymatic components of AOS, and disturbed lipid metabolism, while CEA was associated with a less pronounced intensification of LPO, slight suppression of AOS, and slight changes in lipid metabolism, which makes this types of analgesia preferable.

Acute Disease↗
PubMed2002

[Effects of selenium-enriched garlic on blood lipids and lipid peroxidation in experimental hyperlipidemic rats].

The modulating effects of selenium-enriched garlic on lipid metabolism disorder and lipid peroxidation were studied in hyperlipidemic rats induced by high fat diet. Adult male and female Wistar rats were divided into 6 groups: (A) normal control; (B) high fat diet (HFD) control; (C) HFD + selenite; (D) HFD + selenium-enriched garlic; (E) HFD + common garlic; (F) HFD + common garlic + selenite. The selenium content of diets in groups A, B and E was 0.08 mg/kg diet, while that of the other 3 groups was 2.7 mg/kg diet. At the end of the experimental period (12 weeks), blood and liver were collected for biochemical measurements and for histopathological examination of liver. The results showed that the serum concentrations of TC, TG and LDL-C in groups C, D and F were significantly lower and HDL-C higher than group B. Female rats were more sensitive to HFD exposure than male rats. The peroxidative status of all four experimental groups was significant inhibited as shown by the lower lipid peroxide (MDA) in liver and higher activities of GPX in erythrocytes and liver and SOD in plasma. Selenium contents in liver and kidney of male rats in groups D and F were higher than group C. Significant accumulation of selenium in erythrocytes was observed in groups D and F. The liver of all four experimental groups revealed ameliorated fatty liver induced by HFD. The amelioration of group D was more prominent than other three experimental groups. The results suggested that selenium-enriched garlic is superior to selenite or common garlic in decreasing the blood lipid level and peroxidative status and slightly better than combined common garlic and selenite.

Animals↗
PubMed1992

[Effect of psychopathological disorders in patients with unstable stenocardia on serum lipids and the indicators of lipid peroxidation].

A total of 193 males suffering from unstable angina pectoris (UAP) were examined against 20 control subjects with stable angina pectoris (SAP) for the serum levels of lipids and activity of lipid peroxidation. The parameters studied varied between the groups. 152 UAP patients exhibited psychopathological disturbances, mainly agitated melancholia. These patients (78.8%) were noticed to have atherogenic shifts in serum lipids and lipid peroxidation products levels increased as compared to those without psychoemotional problems. It was found that in UAP psychopathologic disturbances contribute to the progress of coronary insufficiency this justifying the use of psychotherapy in combination with drugs in UAP patients.

Adult↗
PubMed1991

[Changes in the lipid and protein components of thymus cell membrane during lipid peroxidation].

Nonenzymatic lipid peroxidation in thymus cell plasma membranes was studied. The composition of lipid and protein components, intensity of fluorescence of the membrane probes (1-anilinonaphthalene-8-sulfonate, 4-dimethylaminochalcon, eosin, pyronin and rhodamine), fluorescence polarization of tryptophan residues of membrane proteins and quenching by acrylamide of intrinsic fluorescence of proteins were determined. Induction of lipid peroxidation by the Fe(2+)-ascorbate system caused changes in the composition and structure of lipids. This was paralleled with changes in the structural-dynamic organization of membrane proteins, transition of some peripheral proteins to the water phase and increased solubilization of integral proteins by Triton X-100.

Animals↗
PubMed1990

Increased rates of lipid exchange between Mycoplasma capricolum membranes and vesicles in relation to the propensity of forming nonbilayer lipid structures.

We have studied the effects of modification of the endogenous phosphatidylglycerol (PG) and diphosphatidylglycerol (DPG) content of the plasma membrane of Mycoplasma capricolum on the kinetics of spontaneous [14C]cholesterol and 14C-labeled phospholipid exchange between M. capricolum membranes and lipid vesicles. The PG/DPG molar ratio of M. capricolum membranes changed when cells were grown in media supplemented with 0.5 mM CaCl2 and/or egg phosphatidylcholine (PC) (10-20 micrograms/ml), increasing from 3.9 to 6.3 on supplementation with Ca2+; this ratio decreased to 1.1 in media supplemented with PC and to 1.8 in media containing both PC and Ca2+. The ratio of palmitate to oleate in both PG and DPG decreased when cells were grown with PC or with PC and Ca2+. Bilayer disruptions were seen in freeze-fracture electron micrographs of trypsin-treated M. capricolum membranes from cells grown with both Ca2+ and PC, and numerous lipidic particles and other bilayer disruptions were observed in trypsin-treated M. capricolum membranes and their lipid extracts. The rates of spontaneous exchange of 14C-labeled cholesterol and PC from membranes isolated from cells grown with PC and Ca2+ to acceptor lipid vesicles were exchanged by approximately 30%, and the rate of the rapidly exchangeable cholesterol pool in intact cells was enhanced by 64%. The enhancements in cholesterol and PC exchange rates are considered to result from structural defects expected in the M. capricolum membranes obtained from cells grown with Ca2+ supplementation. Our findings parallel previous examples of functional modifications of membranes induced by bilayer instability arising from a pretransitional state leading to the onset of a nonlamellar phase.

Calcium↗
PubMed1986

Potentiation of free radical-induced lipid peroxidative injury to sarcolemmal membranes by lipid amphiphiles.

The effects of naturally occurring lipid amphiphiles on free radical-mediated peroxidative injury in isolated canine sarcolemma were studied. Highly enriched canine myocytic sarcolemmal membranes were preincubated for 10 min at 37 degrees C with or without different amphiphilic lipids before the addition of a free radical-generating system consisting of dihydroxyfumarate and Fe3+-ADP. Lipid peroxidation, assayed as malondialdehyde formation, was catalyzed linearly up to 40 min in the control samples. Pretreatment of the sarcolemma with palmitoyl-CoA, palmitoylcarnitine, or lysophosphatidylcholine accelerated the initial rates (20 min) of peroxidation in a concentration-dependent manner (10-100 microM) and achieved maximal stimulation (240%, 160%, and 210%, respectively, of controls) at 50 microM concentrations of each of these amphiphiles. However, free fatty acids, CoA, and carnitine were without effect. These promoting effects of the amphiphiles persisted over a wide pH range (pH 6.0-7.8) and exhibited additive effects when lower levels of different amphiphiles were combined together. Associated with the accelerated rates of peroxidation produced by palmitoyl-CoA and palmitoylcarnitine were greater losses in the activity of sarcolemmal (Na,K)-ATPase. Since all three kinds of amphiphilic lipids accumulate during ischemia, this study suggests a novel mechanism of potentiation of sacolemmal membrane injury when free radicals are present.

Animals↗
PubMed1988

Streptozotocin-induced diabetes in rat. II. Lipid and lipid peroxide changes of lipoprotein fractions in diabetes complicated by hypertension and myocardial infarction.

Lipid peroxide levels and plasma lipids were studied in plasma lipoprotein fractions of streptozotocin diabetic rats, spontaneous hypertensive rats (SHR) + diabetes, and in myocardial infarction rats (MIR) + diabetes. The duration of diabetes in all experimental groups was 2.5 months. We found a tendency of elevation of cholesterol in VLDL and fall in HDL2 but the differences were not significant. Total plasma triglycerides were increased in the three diabetic groups, and the increase was due to LDL fraction but again the differences were not significant. The lipid peroxide (LP) level in total plasma showed a significant increase in the three diabetic groups: in Wistar diabetic rats LP increased 3 times, in MIR + diabetes 3.5 times, and in SHR + diabetes 5 times. The increase of LP in the three diabetic groups was due to LDL with good correlation (r = 0.60) between LP and triglycerides in LDL of the three diabetic groups. The results are in agreement with the concept of the importance of lipoprotein fraction changes: increased cholesterol, triglycerides and lipid peroxides in atherogenic (VLDL and LDL) fractions, and decreased levels in antiatherogenic (HDL, HDL2) fractions in diabetes mellitus.

Animals↗
PubMedDate not supplied

[Effects of different types of nutritional imbalance on lipid peroxidation and viscosity of membrane lipids].

For 90 days male August rats were kept on 5 diets: (I) balanced semisynthetic, (II) with amino acid unbalance, (III) with excess polyunsaturated fatty acids (PUFA), (IV) with vitamin E deficiency, and (V) polyunbalanced (amino acid unbalance, excess PUFA, vitamin E deficiency). In liver microsomes, the authors studied the kinetics of malonic dialdehyde accumulation in the course of NADPH-dependent lipid peroxidation (LP) and microviscosity of the lipid phase of microsomal membranes according to eximerization of the pyrene fluorescent hydrophobic probe. The microsomes of the animals fed diets I, III and IV showed on the average a 50 to 55% increase in the rate of MDA formation, whereas those of rats on diet V a 78% increase as compared with appropriate characteristics in the animals fed diet I. A good correlation was established between the decrease in the pyrene eximerization rate and accumulation of lipid peroxides: r = 0.09 (P less than 0.05). The possibility of affecting LP in the membranes by the goal oriented modification of the diet is discussed. The participation of proteins, lipids and tocopherol in the maintenance of the membrane structure is described.

Animals↗
PubMed1983

[Lipid characteristics of actinomycetes. I. The content and composition of lipid fractions].

The original experimental results and review of the literary data on the composition of total extractable Lipids in Streptomyces genus strains at the different growth stages grown on various composition media are given. The results of the investigation on lipids (including those of the membranes) which have not been earlier found in Streptomycetes are discussed. Special attention is given to changes of the membrane lipid component in connection with the growth phases and cultural conditions, particularly to the different rate of the membrane nitrogen-containing lipids interchange depending on the phosphate content in the medium.

Actinomycetales↗
PubMed1981

Regional effects of sulfur dioxide exposure on the guinea pig brain lipids, lipid peroxidation and lipase activity.

Experiments to evaluate the neurochemical action of gaseous pollutants were performed in a specifically designed inhalation chamber. Exposure of guinea pigs to 10 ppm of SO2 for one hour daily for 21 days produced a significant depletion of total lipids and free fatty acids in all brain regions. Phospholipid and cholesterol content of the cerebellum and brain stem were also decreased, but were increased in cerebral hemisphere. Esterified fatty acids were depleted in the cerebral hemisphere and brain stem, but exhibited increment in the cerebellum. The rate of lipid peroxidation and the activity of lipase were increased significantly in all the regions of the brain. The results clearly indicate that SO2-exposure induces degradation of brain lipids. Interestingly, the lipid contents are affected differentially in the various parts of the brain.

Animals↗
PubMed1977

[Change in the concentration of total lipids, phospholipids and neutral lipids in rat liver mitochondria and microsomes during chemical carcinogenesis].

Sharp increase in the content of total lipids and, especially, neutral lipids, and considerable decrease in the content of phospholipids were observed in liver microsomes and mitochondrias from liver of tumour-bearing rats in the process of the growth of sarcoma, induced by a single injection of 3,4-benzpyrene. The injection of anthracene, a non-cancerogenous hydrocarbon, practically did not affect the lipid composition of rat liver subcellular particles. Thus, the disturbances in normal functioning of subcellular particles under cancerogenesis are due to considerable change in the chemical composition of biomembranes. The data obtained confirm our hypothesis on lipid mobilization under tumour growth.

Animals↗
PubMedDate not supplied

[Effect of L-carnitine on lipid peroxidation and lipid composition in blood serum in hemic hypoxia].

Sodium nitrite has been studied for its effect on lipid metabolism of Wistar line rats. It is shown that a single administration of sodium nitrite in account 5 mg per 100 g of the body weight results in the intensification of lipids peroxidation, hyperbetalipoproteinemia, hypertriglyceridemia, hypercholesterolemia and to the decrease of the coefficient phospholipids/cholesterin/. Prophylactic administration of carnitine chloride in account of 20 mg per 100 g of the body weight stabilizes the level of lipids peroxidation, decreases concentration of total lipids, triglycerides, total cholesterin, phospholipids, lipoproteids of low and very low density, in the rat blood serum, normalizes the coefficient phospholipids/cholesterin.

Acute Disease↗
PubMedDate not supplied

[Blood lipids, lipid peroxidation and the effect on them of antianginal preparations in ischemic heart disease patients].

The origin and development of ischemic heart disease (IHD) is attended with activation of lipid free-radical oxidation facilitating further advancement of the disease and with decrease of the organism's antioxidant protection. The antianginal drugs which are used in IHD treatment differ in their effect on the blood lipid composition and their peroxidation. beta-Adrenoblocking agents may cause proatherogenic disorders of the blood lipid graph, this increases the risk of IHD advancement. Long-acting nitro preparations are lipid-neutral. Calcium antagonists, mainly those of the nifedipin group, suppress LPO superactivity, possess a high antioxidant effect, and, probably, retard the advancement of coronary atherosclerosis and IHD.

Animals↗
PubMed1991

Familial aggregation of lipids and lipoproteins in families ascertained through random and nonrandom probands in the Stanford Lipid Research Clinics Family Study.

We examined the familial aggregation of lipids [total cholesterol (CH) and triglyceride (TG)] and lipoproteins [high-density lipoprotein cholesterol (HDL) and low-density lipoprotein cholesterol (LDL)] in families ascertained through random and nonrandom probands in the Stanford Lipid Research Clinics Family Study. Nonrandom probands were selected because their lipid levels at a prior screening visit exceeded a certain prespecified threshold. The statistical method is based on selection through indirect truncation on a correlated trait (in which the likelihood function is conditioned on the actual event that the proband's value is beyond the threshold). This method allows for estimation of the path model parameters in randomly and nonrandomly ascertained families jointly and separately, thus enabling tests of heterogeneity between the two types of samples. The results suggest that the multifactorial transmission is homogeneous in the random and hyperlipidemic samples for CH. However, the evidence for heterogeneity is moderate for LDL, marked HDL, and mixed for TG. The general pattern of observed results is for somewhat higher genetic heritabilities in the random than nonrandom samples, which is compatible with a higher prevalence in the random sample of certain dyslipoproteinemias associated with nonelevated lipids. Substantial genetic heritability is found for CH, HDL, and LDL, with somewhat lower estimates for TG. Cultural heritability is low but significant for all four traits. Little or no spouse resemblance or nontransmitted shared sibship effects are seen. In contrast to the findings from previous studies, little or no parental cultural transmission is seen.

Adult↗
PubMed1982

[Effect of long-time supply of medium-chain triglycerides on postprandial lipid metabolism and fatty acid pattern of membrane lipids in rats].

To characterize the effect of long-term supply medium-chain triglycerides on the lipid metabolism, the authors determined under postprandial conditions the ratio between the ketone body concentrations in the blood and the liver, the in vitro fatty-acid synthesis in the liver and the adipose tissue, the plasma and liver lipids and the fatty-acid and phospholipid spectra of the plasma and the erythrocytic, thrombocytic and liver mitochondrial membranes, in rats after 9 weeks on an isoenergetic diet containing 12% of medium-chain triglycerides or lard. The long-term supply of medium-chain triglycerides induced a 3-fold increase of the fatty-acid synthesis in the liver and the fatty tissue. In contrast to this, no differences in the concentrations of acetacetate and beta-hydroxybutyrate were detected in the liver and the adipose tissue. The triglyceride and cholesterol contents in the liver were significantly reduced. In spite of the increase of palmitic acid proportion as the end product of the de novo fatty-acid synthesis in the plasma lipids and the erythrocytic membrane, the proportion of essential fatty acids in the membrane lipids under study was not affected; the simultaneous supply of 3% of sunflower oil meets the requirements for essential fatty acids.

Adipose Tissue↗
PubMed1991

Prediction of total body lipid from total body water in rats. Part 2. In vivo estimation of total body lipid by tritium water dilution.

Body composition data estimated for normal young, normal adult, and adult obese Wistar rats by a tritiated water (THO) dilution procedure (b. wt. range 119-237 g, n = 31; 305-597 g, n = 43; 274-381 g, n = 6) were compared with the results of whole body analysis. As for the predicted total body lipid (TBL), the content was calculated from the virtual THO-dilution space estimated by a simple micro-method and a regression equation between TBL [%] and DM [%] (dry matter) content (Part 1. Relations between directly measured major body components. Nahrung 35 (1991) 581. Due to different degrees of overestimations in the animal groups examined, the THO-space can be corrected via subtraction of 3.8%, 2.2% and 1.1% in the sequence young, obese, and adult groups. The derived TBL [%] data show a non-significant deviation of less than 1 g/100 g b. wt. in comparison to the three group means after direct lipid determinations. In the best case, i. e. after the additional elimination of extremely overestimated values for total body water (outliers) the combined tritium-derived lipid values (y) are correlated with the lipid data obtained analytically (x), both as proportion of the body weight, by the regression equation y = 0.848 + 0.963 x, r = 0.985, Sy.x = 1.77, n = 58. For a group of young rats (n = 14) after a pre-experimental supplementation with a sucrose solution, TBL values, not significantly different from analytically determined ones, could be calculated without any corrections.

Animals↗
PubMed2007

Lipid-protein cargo transfer: a mode of direct cell-to-cell communication for lipids and their associated proteins.

Cells in tissues or in experimental cell colonies respond to stimuli in a co-ordinated manner when they are electrically and chemically coupled by gap junctions. These junctions permit the cell-to-cell passage of small molecules, such as inositol tris phosphate (IP(3)) within the colony and are important in co-ordinating tissue activity. This is the only recognised mechanism of direct chemical signalling that does not involve the release of an extracellular messenger between cells. However, the data in this article demonstrates a new mode of intercellular communication. Two potentially important signalling lipids, PIP(2) and ganglioside G-M1 were shown to move between cells in colonies by tracking (i) fluorescent lipids loaded into the plasma membranes of individual cells in a cell colony using a novel micropipette technique and (ii) movement of fluorescent lipids after localised photobleaching. Furthermore, a large protein molecule, cholera toxin B subunit bound to extracellularly facing ganglioside G-M1 was also shown to transfer between cells. The transfer was inhibited by pre-treatment with poly-L-lysine and polyethylenimine, suggesting a role for tight junctions, perhaps by permitting diffusion of lipids and their protein "cargo" across these cell-to-cell contact points. This is a hitherto unsuspected form of molecular signalling within cell colonies and tissues which may have implications for understanding co-ordinated cell colony behaviour.

Biological Transport↗