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PubMedDate not supplied

[Lipid peroxidation and change in the lipid fraction of plasma in patients with hypertonic disease].

Effect of lipid peroxidation on content and composition of blood plasma lipids was studied in 20 patients with hypertension within various periods after hypertonic crisis. Alterations in blood plasma lipid spectrum were shown to be related to initiation of lipid peroxidation in cell membranes. Dynamics of lipid peroxidation in individual blood plasma lipid fractions appears to reflect the adaptation under conditions of the pathological state of the organism.

Adult↗
PubMed1991

Intramolecular excimer formation of pyrene-labeled lipids in lamellar and inverted hexagonal phases of lipid mixtures containing unsaturated phosphatidylethanolamine.

The rates of intramolecular excimer formation of di(1'-pyrenemyristoyl)phosphatidylcholine (dipyPC) in dioleoylphosphatidyl-ethanolamine (DOPE), egg PE/diolein (DG) and dilinoleoyl-PE (DLPE)/1-palmitoyl-2-oleoyl-PC (POPC) were studied at different temperatures and lipid compositions. Both the excimer-to-monomer intensity ratio and the excimer association rate constant were employed to quantify the rate of excimer formation. The latter was calculated from the measured monomer fluorescence lifetime of dipyPC. We observed that the rate of excimer formation was sensitive to either the temperature-induced or lipid composition-induced lamellar-to-inverted hexagonal phase transition of the above lipid systems. As the lipids entered the inverted hexagonal phase, the rate of excimer formation increased at the temperature-induced phase transition for DOPE, but decreased at the composition-induced phase transition for both TPE/DG and DLPE/POPC systems by increasing the DG% and decreasing the PC%, respectively. We conclude that the rate of intramolecular excimer formation of dipyPC in the non-lamellar phase is influenced both by the intra-lipid free volume of the hydrocarbon region and the intra-rotational dynamics of the two lipid acyl chains.

Chemical Phenomena↗
PubMed1978

[Comparative study of lipid A from pertussis microbes differing in the toxicity of their O-antigens. I. Chemical composition and stability of the bond between lipid A and the specific polysaccharide in B. pertussis lipopolysaccharide].

Data presented in this work indicated that antigens, contrastive by toxicity, obtained by Boiven's method and O'Neill and Tood's method from two strains of Bordetella pertussis differed by stability of lipid A binding with the specific polysaccharide. The influence of duration of the lipopolysaccharide hydrolysis on the fatty acid content in lipid A, and of heptose in the specific polysaccharide was demonstrated. Lipid A fatty acid composition was studied. It is supposed that bound fatty acids are presented as C14 and C19--C22. There was a correlation between the antigen toxicity and the stability of lipid A bond with the specific polysaccharide. Stability of the lipopolysaccharide complex bond depended on heptose and lipid A content and on the composition and the amount of fatty acids in the lipid A preparations.

Antigens, Bacterial↗
PubMed1990

Sequential changes in lipid metabolism and the fatty acid profile in liver lipids during fasting and sepsis.

The sequential changes in lipid metabolism and in the fatty acid profile of liver lipids during fasting and sepsis were studied. Liver and blood specimens were taken from normally fed rats and from nonseptically and septically fasted rats at 5, 24, and 48 hr. Sepsis was induced by injecting live Escherichia coli bacteria intraperitoneally. Sepsis attenuated the fasting-induced increase in beta-hydroxybutyrate and reduced liver and serum triglycerides at 5 hr. There was a percentage decline in the most abundant fatty acids in neutral lipids, namely oleic (18:1w9) and linoleic (18:2w6) acids. This was seen throughout fasting and septic fasting. These results indicate that 18:1w9 and 18:2w6 are used as energy substrates and are oxidized to beta-hydroxybutyrate during fasting and mainly to carbon dioxide during septic fasting. On the contrary, the most abundant fatty acids in phospholipids, stearic (18:0), arachidonic (20:4w6), and docosahexaenoic (22:6w3) acids, accumulated in neutral lipids and in phospholipids throughout fasting. However, during sepsis this accumulation was reduced in neutral lipids and reversed to a level below that in the fed and fasted state in phospholipids. These results indicate that a disturbance in membrane integrity and function induced by septic fasting may have pathophysiological consequences for lipid metabolism and liver function during sepsis.

Animals↗
PubMed1985

Lipid storage disease: Part II. Ultrastructural pathology of lipid storage cells in sphingolipidoses.

The ultrastructural pathology of the stored materials in lipid storage cells, particularly of macrophagic nature, in various disorders of sphingolipidosis was investigated. Cell morphology of the lipid storage cells was largely divided into two groups; one had peculiar cell morphology, such as Gaucher cells or globoid cells, and the other showed the appearance of foam cells. These cytological characteristics of the lipid storage cells were closely related to the ultrastructural configuration of lipid storage inclusions. By transmission electron microscopy, the fundamental structures of the stored materials were classified into two types; tubular and lamellar. The tubular structures were formed by accumulation of ceramide or monohexosyl ceramide, whereas the lamellar structures were formed by accumulation of larger sphingolipids than monohexosyl ceramide. These tubular structures were proven to consist of multilayers of lamellae, which are considered fundamentally similar to the lamellar structures. Almost all the lipid storage inclusions are considered to be of lysosomal origin, because of their encirclement by a single unit membrane and localization of acid phosphatase activity, and participation of heterophagic or autophagic mechanisms as for the development of the inclusions may be noted. Besides, the occurrence of secondary lipid storage was pointed out in some disorders of sphingolipidosis.

Fabry Disease↗
PubMed1981

Antibody precipitation of lipid vesicles containing myelin proteins: dependence on lipid composition.

Antibody binding to human CNS myelin basic protein and to rabbit sciatic nerve myelin P-2 in their lipid-bound and water-soluble conformations has been investigated. 125I-labeled basic protein or P-2 was bound to the surface of liposomes (vesicles) of different acidic lipids, phosphatidylethanolamine (PE), phosphatidylserine (PS), phosphatidic acid (PA), phosphatidylglycerol (PG), and cerebroside sulfate (CBS). The antibody was prepared against aqueous solutions of basic protein and P-2. Antibody binding to the proteins in liposomes was measured by precipitation of the liposomes by using a double antibody radioimmunoassay. The amount of 125I-basic protein precipitated was lest when the protein was bound to PA and increased in the order PA less than PS less than PG less than CBS less than PE approximately equal to basic protein in solution, suggesting that the antigenic determinants were lest exposed or most altered for PA and most exposed for PE. This agreed fairly well with previously published biophysical studies that suggested that hydrophobic segments of the protein penetrated into the lipid bilayer and that this penetration decreased in the order PA approximately equal to PG greater than PS greater than CBS greater than or equal to PE. The amount of 125I-P-2 precipitated was least for PA and CBS and increased in the order PA approximately equal to CBS less than PS less than PG less than PE approximately equal to P-2 in solution. However, the differences were less than for basic protein and the effect of CBS was different for the 2 proteins. Less is known about the conformation of P-2 in these lipids but it is known that lipids increase its disease-inducing activity. These results indicate that interaction with lipid may sequester or alter the conformation of antigenic determinants such that antibody binding decreases.

Animals↗
PubMed1984

Identification and detection of in situ cellular and regional differences of lipid composition and class in lipid-rich tissue using hot stage polarizing light microscopy.

To determine whether in situ tissue lipid characterization is possible, we examined carefully prepared frozen sections from a variety of lipid-rich tissues of the cholesterol-fed rabbit by hot stage polarizing light microscopy and conventional histologic staining. Heating of frozen sections to less than 60 degrees C did not affect tissue architecture or staining characteristics making pathologic and physical chemical correlations possible. The melting temperatures of cholesterol ester inclusions in individual foam cells in rabbit atherosclerotic lesions and adrenal gland could be determined as well as the melting characteristics of crystals and triglyceride in these and other tissues. Differential scanning calorimetry and polarized light transmittance were used to confirm melting temperatures determined by microscopy. Combining data from histologic staining, polarizing light microscopy, and the thermal characteristics of lipid enables the various lipid classes to be identified within individual cells. Differences in melting temperatures between lipids of the same class give indications of the degree of saturation of the lipids. Regional differences of cholesterol ester-melting temperatures in the chow-fed rabbit adrenal cortex were detected which implied differences in chemical composition. Cholesterol feeding raised the melting temperature and tended to abolish the marked regional differences in melting temperature of the cholesterol esters in the adrenal cortex. Rabbit atherosclerotic lesions, induced by balloon deendothelialization and cholesterol feeding, revealed differences in foam cell-melting temperatures within the same lesion. Melting temperatures of cholesterol ester deposited in the liver were more uniform. Each tissue studied revealed distinctly different cholesterol ester-melting characteristics.

Adipose Tissue↗
PubMedDate not supplied

[Effect of typhoid endotoxin and its lipid component on the lipid concentration of myocardial tissue of mice].

Content of triacylglycerides and cholesterol esters was rapidly and distinctly increased while di- and monoacylglycerides appeared in heart muscle after intraperitoneal administration of hyphoid endotoxin into mice. Concentration of free fatty acids exceeded 3-fold the initial level within a day. At the same time, content of free cholesterol was also increased. Lipid fractions (lipids A and B) isolated from the lipopolysaccharides altered distinctly the lipid composition in mice myocardium. An increase in acylglycerol content was noted though it was less distinct as compared with the lipopolysaccharide effect. Lipid A and especially lipid B decreased the content of free fatty acids and of free cholesterol in myocardial tissue. Content of total phospholipids was unaltered in heart muscle after the lipopolysaccharide administration but these lipid fractions increased distinctly their content.

Animals↗
PubMed1980

Promethazine administration to rats and CCl4 induced lipid peroxidation of liver microsomal lipids.

Promethazine inhibited CCl4 stimulated microsomal lipid peroxidation in vitro at concentrations ranging from 10(-3) to 10(-8)M. CCl4 administered to rats at a dose of 1 ml/kg decreased the arachidonic acid content of microsomal lipids after 6 hours of intoxication. Prior promethazine treatment, at dosage regimes that preclude CCl4 induced liver necrosis at 24 hours, did not significantly prevent the CCl4 induced decrease in arachidonic acid content. Moreover, promethazine itself produced a similar decrease but in complete absence of liver damage. Results suggest that either lipid peroxidation is not relevant to liver injury or that the arachidonic acid decrease in microsomal lipids is not evidence for lipid peroxidation occurrence or that promethazine effects are not related to inhibition of lipid peroxidation.

Animals↗
PubMed1994

Three enzymes involved in oligosaccharide-lipid assembly in Chinese hamster ovary cells differ in lipid substrate preference.

Initial steps in N-linked glycosylation involve formation of a large oligosaccharide structure on a lipid carrier, dolichyl phosphate. We have previously characterized Chinese hamster ovary (CHO) glycosylation mutants (Lec9 cells) that utilize the polyisoprenoid lipid polyprenyl phosphate rather than dolichyl phosphate in these glycosylation reactions. Polyprenyl phosphate differs from dolichyl phosphate only in the degree of saturation of its terminal isoprenyl unit. Our goal was to determine whether the glycosylation defect of Lec9 cells could be explained simply by knowing lipid substrate preferences of the enzymes involved in the assembly of oligosaccharide-lipid (OSL) intermediates. In this study, we have used in vitro assay systems to compare the ability of dolichyl phosphate and polyprenyl phosphate to act as substrates for three glycosyl transferase enzymes involved in OSL assembly. In order to insure that we were only examining lipid substrate preferences of the enzymes and not other potential defects present in Lec9 cells, we used membranes prepared from wild-type cells in these in vitro reactions. Our results indicate that one of the enzymes, mannosylphosphoryldolichol (MPD) synthase, exhibited a significant preference for the dolichol substrate. Glucosylphosphoryldolichol (GPD) synthase, on the other hand, showed no binding specificity for the dolichol substrate, although the enzyme used the dolichol substrate at a twofold higher rate. N,N'-diacetyl-chitobiosylpyrophosphoryldolichol (CPD) synthase was able to use either lipid substrate with equal efficiency. These results suggest that not all glycosyl transferases in this pathway show a preference for dolichol derivatives.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1977

Biosynthesis of lipid-linked oligosaccharides in cotton fibers. Stimulation by lipids from pig liver.

An acidic lipid fraction isolated from pig liver (Forsee, W. T. & Elbein, A.D. (1976) Proc. Natl. Acad. Sci. U.S.A. 73, 2574-2578) stimulated the incorporation of mannose from GDP-[14C]mannose into lipid-linked oligosaccharides using a particulate enzyme fraction from maturing cotton bolls. This lipid fraction did not stimulate mannose incorporation into the mannosylphosphorylpolyprenol. The 14C-oligosaccharides, formed in the presence or absence of the pig liver "acceptor" lipid, were released from the lipid-linked oligosaccharides by mild acid hydrolysis and were isolated by paper chromatography. Both sets of 14C-oligosaccharides had similar mobilities suggesting that they were qualitatively similar, except that those formed in the presence of "acceptor" lipid had much more radioactivity. The individual oligosaccharides were purified on a calibrated column of Sephadex G-25 and were then subjected to various treatments to obtain information about their structures. The molecular weights of the larger oligosaccharides ranged from about L1210 to 1720 indicating they probably contained from 6 to 10 sugar residues. Strong acid hydrolysis of the oligosaccharide with a molecular weight of 1350, followed by reduction with NaB3H4, gave a ratio of [3H]hexitol to [3H]hexosaminitol that was compatible with the molecular weight (about 5:2). However, the hexitol fraction contained small amounts of [3H]glucitol in addition to [3H]mannitol. Thus, this oligosaccharide may contain small amounts of glucose in addition to mannose and GlcNAc. When the smaller oligosaccharides (i.e. those having 5 or 6 sugars) were treated with alpha-mannosidase, essentially of all the 14C was released as mannose, but only 30 to 50% of the radioactivity could be released from the larger oligosaccharides by this enzyme. Acetolysis of the oligosaccharide with a molecular weight of 1720 released the radioactivity as mannobiose and mannotriose suggesting that these oligosaccharides contain di- and trisaccharide branches linked to the main chain in 1 leads to 6 linkages.

Animals↗
PubMed1995

Effect of selenium on lipids and some lipid metabolising enzymes in DMBA induced mammary tumor rats.

Current evidences clearly point out that an increase in lipid peroxidation influences lipid metabolism in cancer patients. Several investigations recognize selenium as a potent antioxidant, as well as an anticarcinogen, in both animal and human systems. Selenium was administered to Wistar rats bearing mammary tumor induced by 7,12-dimethylbenz(a)anthracene (DMBA) to study alterations in the concentration of lipid profiles and in the activities of some lipid metabolising enzymes. Control and tumor-bearing rats administered with selenium, were fed 5 mg sodium selenite/kg diet from the day of tumor induction. Plasma total lipids, total cholesterol, free fatty acids, triglycerides, phospholipids, VLDL and LDL cholesterol were significantly lower in selenium-treated rats bearing tumors, whereas, plasma ester cholesterol and HDL cholesterol were significantly greater due to selenium administration in DMBA induced-tumor rats. Total lipase and lecithin: cholesterol acyltransferase registered greater activities in plasma of selenium administered rats with tumor, while the activity of preheparin lipoprotein lipases in plasma of rats bearing tumors was lower due to selenium administration. These observations clearly indicate the effect of selenium in correcting the abnormalities of lipid metabolism in tumor-induced rats.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1997

Lipid signals detected by NMR proton spectroscopy of whole cells are not correlated to lipid droplets evidenced by the Nile red staining.

Nile red staining was used to detect lipid droplets in the K562 cell line sensitive and resistant to adriamycin and their resistance-reversing counterparts. The staining obtained was compared to the intensity of lipid signal detected in proton nuclear magnetic resonance spectra. From the four cell lines used, a lack of correlation was observed between the NMR signal and the Nile red staining. For example, the sensitive K562 cells, with the highest level of NMR signals, showed only few cells containing lipid droplets. We concluded that is lipid droplets can participate to lipid signal in NMR spectra, other lipids must also participate to these resonance.

Doxorubicin↗
PubMed1999

Dietary iron overload and induced lipid peroxidation are associated with impaired plasma lipid transport and hepatic sterol metabolism in rats.

Although hemochromatosis is characterized by dramatic morphological and functional alterations in the liver, little is known about the effects of an excess of iron on lipid metabolism. Therefore, we determined the effect of chronic iron overload on plasma lipid profile and lipoprotein composition, as well as on hepatic cholesterol metabolism and biliary sterol output. Rats administered a diet enriched with 3% iron carbonyl for 12 weeks displayed a 30-fold increase in iron (P <.0001) and a 5-fold rise in malondialdehyde (P <.001) in the liver. When compared with pair-fed controls, iron-overload rats showed a significant increase in triglycerides (P <.005), free cholesterol (P <.006), cholesteryl ester (P <.007), and high-density lipoprotein (HDL)-cholesterol (P <. 003). Triglyceride and cholesteryl ester enrichment, protein depletion, size increase, and apolipoprotein composition alterations characterized the very low density lipoprotein (VLDL) and HDL particles of iron-overload rats. Assessment of the activity of intracellular key enzymes for cholesterol homeostasis in these rats disclosed a reduction in 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase (66%, P <.005) and cholesterol 7alpha-hydroxylase (58%, P <.0004) with an increment of acyl-CoA: cholesterol acyltransferase (62%, P <.002). The lack of optimal enzymatic activity may be a result of marked membrane lipid peroxidation that brings about fluidity drop (P <.029) in microsomes of iron-overload rats (5.00 +/- 0.013) versus controls (8.20 +/- 0. 03), reflected by polarization. A decline of the pool size of cholesterol and bile acids was noted in iron-overload rats during a 6-hour bile drainage. Our results show that experimental iron overload causes marked perturbations in plasma lipid transport and hepatobiliary sterol metabolism. Given the positive correlation of malondialdehyde with most of the altered parameters, iron-catalyzed lipid peroxidation may well be one of the involved mechanisms.

Alanine Transaminase↗
PubMed1992

Changes in lipid peroxidation levels and lipid composition in the lungs, livers, kidneys and brains of mice treated with paraquat.

We examined lipid peroxide levels and the lipid composition of homogenates prepared from the lungs, livers, kidneys and brains of 48 male ICR mice treated with 30 mg kg-1 paraquat (1,1'-dimethyl-4,4'-bipyridylium dichloride). The mice were divided into eight groups, in which they were killed 0, 1.5, 3, 6, 12, 24, 48 and 120 h after the administration of paraquat. A significant increase in the lipid peroxide level was identified only in the liver. Change in lipid composition was identified in all the examined organs. However, the change was not a characteristic one in which there is a selective decrease of polyunsaturated fatty acids which become degraded in a lipid peroxidation reaction. It is possible that the mechanism of paraquat toxicity may differ in different organs.

Animals↗
PubMed1988

Neutral lipid storage disease with ichthyosis: lipid content and metabolism of fibroblasts.

Neutral lipid storage disease with ichthyosis is a newly recognized heritable disorder characterized by widespread cellular triglyceride storage. Lipid metabolism in fibroblasts cultured from three affected family members was studied. The stored lipid is triglyceride composed of an unremarkable fatty acid profile and derived from both exogenously-supplied and endogenously-synthesized fatty acids. Lipid storage could not be corrected by prolonged culture in lipid-depleted media. Acetyl CoA carboxylase activity and beta-oxidation of palmitate were both normal. Taken together, these studies exclude a primary defect of fatty acid uptake, over-synthesis or impaired beta-oxidation. Moreover, triacylglycerol lipase activity of homogenates of fibroblasts from patients with NLSDI examined over the range of pH 3.5-8.5 was normal.

Fatty Acids↗
PubMed2002

Lipid-lipid recognition in fluid bilayers: solving the cholesterol mystery.

Nearest-neighbour recognition measurements take 'molecular-level snapshots' of lipid organization in fluid bilayers by detecting and quantifying the thermodynamic tendency of two lipids to become nearest-neighbours. Recent nearest-neighbour recognition experiments have clarified the structural role that cholesterol plays in biological membranes. They have also clarified the influence that the linkage region of sphingolipids, the sugar head group of glycolipids, and lipid-peptide interactions have on lipid-lipid recognition.

Cholesterol↗
PubMed1999

A new model system for lipid interactions in stratum corneum vesicles: effects of lipid composition, calcium, and pH.

We prepared large unilamellar vesicles (LUVs) with three different stratum corneum lipid compositions: constant amounts of ceramides (55 wt %) and fatty acids (15%) with varying amounts of cholesterol sulfate (0-15%) and cholesterol (15-30%). One of the compositions served as a model for normal stratum corneum, while the second one served as a model for recessive X-linked ichthyosis stratum corneum. The third composition consisted of no cholesterol sulfate. Intervesicle lipid interactions in these LUVs were monitored by fluorescence methods for content leakage, and contents mixing at pH 9, in the absence and presence of Ca2+, and at pH 6. Since the content leakage and contents mixing assays were originally developed for phospholipid vesicles, we characterized the probe binding and the probe quenching properties for stratum corneum LUV systems, and modified the assays slightly accordingly. The time-dependent fluorescence intensity changes in the probe-containing LUVs at pH 9 and 6 and in response to the addition of calcium were monitored. Our results demonstrated that all three types of LUVs were relatively stable at pH 9. Addition of Ca2+ or decreasing the pH to 6 activated intervesicle lipid mixing followed by vesicle fusion and lysis. We found that the LUVs with no cholesterol sulfate and 30% cholesterol exhibited a more extensive Ca2+- or low-pH-activated intervesicle lipid interaction than LUVs with either 5% cholesterol sulfate and 25% cholesterol or 15% cholesterol sulfate and 15% cholesterol. These results suggest that fusogenic agents such as Ca2+ and H+ act to neutralize the fatty acids in the lipid bilayer of stratum corneum vesicles. The inclusion of 5-15% cholesterol sulfate helps to prevent the collapse of fused vesicles into other structures.

Animals↗