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PubMedDate not supplied

Malondialdehyde formation from lipid peroxides in the thiobarbituric acid test: the role of lipid radicals, iron salts, and metal chelators.

Most of the chromogen formed when peroxidized material is heated with thiobarbituric acid (TBA) can be ascribed to a colored complex formed between malondialdehyde (MDA) and TBA. Even when little MDA is present, large amounts of MDA-TBA adduct can be formed. This is because lipid peroxides break down to release MDA during the test conditions. Iron is not essential for the breakdown of the peroxides but is essential for the formation of TBA reactivity. This can be related to the ability of iron to decompose lipid peroxides with the release of peroxy radicals, which are precursors of MDA. These peroxy radicals, when released, can initiate further peroxidation during the heating stage of the TBA test. Fatty acids in the absence of lipid peroxides do not undergo significant peroxidation during the acid-heating stage of the TBA test.

Chelating Agents↗
PubMed1984

Stratum corneum lipid abnormalities in ichthyosis. Detection by a new lipid microanalytical method.

Although the biochemical diagnosis of the ichthyoses is still in its infancy, the two recessively inherited types, recessive X-linked ichthyosis (RXLI) and nonbullous congenital ichthyosiform erythroderma (CIE), are accompanied by stratum corneum lipid abnormalities. However, in RXLI, cholesterol sulfate accumulates; in CIE, massive quantities of n-alkanes accumulate. The diagnosis of these disorders has required large quantities of scale for sequential, quantitative thin-layer chromatography (TLC). In this study, we sought to confirm the previously described lipid abnormalities with the use of a rapid, recently developed microchromatographic technique that employs silica gel-coated quartz rods and flame ionization detection (Iatroscan). The cholesterol sulfate content of RXLI (n = 5) scale and the n-alkane content of CIE (n = 8) scale were determined by both TLC and the microchromatographic technique. Less than 10 mg of scale and even single punch biopsy specimens sufficed for the microchromatographic technique, whereas more than 50 mg of scale were required for TLC. Since the microchromatographic technique can rapidly detect diagnostic biochemical abnormalities from readily obtainable, small tissue samples, this method could eventually supplant or supplement standard lipid biochemical techniques for the diagnosis of cutaneous lipidoses.

Alkanes↗
PubMed1982

[Role of the enterohepatic circulation of endogenous lipids in food lipid absorption].

In preliminarily operated dogs with fistulas in stomach and different portions of the small intestine, the liver-intestinal circulation of endogenous phospholipids and cholesterine aided to form the chimus all the lipid fractions of which were absorbed proportionally. The recirculation of endogenous lipids seems to be one of the physiological mechanisms of lipid absorption from food in the small intestine.

Animals↗
PubMed1982

[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↗
PubMed1982

The Cincinnati Lipid Research Clinic family study: cultural and biological determinants of lipids and lipoprotein concentrations.

A general linear model is described here for cultural and biological inheritance of lipids and lipoproteins. This model involves 10 parameters to be estimated from a total of 17 correlations, leaving ample degrees of freedom to test the goodness of fit. The model fits very well to each of the five lipid and lipoprotein variables analyzed here from a Lipid Research Clinic family data set. Both genetic and cultural inheritance are significant for each trait with the single exception that triglyceride levels fail to support genetic inheritance. Under the most parsimonious hypothesis, the genetic heritability (h2) ranges from .194 +/- .092 for triglyceride to .624 +/- .093 for low-density lipoprotein-cholesterol. Cultural heritability ranges from .070 +/- .030 for total cholesterol to .149 +/- .034 for triglyceride.

Adult↗
PubMed1980

Lipid composition and gonadotropin-mediated lipid metabolism of the M5480 murine Leydig cell tumor.

The effects of human choriogonadotropin (HCG) stimulation on lipid composition in the murine Leydig cell tumor M5480 grown subcutaneously were determined. The main lipids of the Leydig cell tumor were found to be largely triacylglycerols and phospholipids. Daily in vivo administration of human choriogonadotropin to tumor-bearing mice for 3 days increased the phospholipid content and altered the phospholipid composition of the tumors. There was no demonstrable change in the levels of triacylglycerols, cholesterol, and cholesteryl esters. HCG had no major effect on the fatty acid patterns of the major lipid fractions with the exception of cholesteryl esters, which had a decreased amount of arachidonic acid following HCG-treatment. Results of in vitro incubations of tumor cells prelabeled with [1-14C]arachidonate showed that the label was lost more rapidly from cholesteryl esters of HCG-treated cells than from control cells during (the 12-hour) incubation. Moreover, less [1-14C]acetate was incorporated into the cholesteryl ester fraction of hormone-treated cells than in control cells. HCG stimulated the activity of cholesteryl ester hydrolase in dispersed cells within 3 hours. These results demonstrate that an acute effect of HCG on tumor Leydig cell metabolism is to increase the metabolism of cholesteryl esters, probably by stimulating cholesteryl ester hydrolase activity. The long term effect is an accumulation of phospholipids which may be utilized for membrane synthesis.

Animals↗
PubMed1994

Lipid determination from monophasic solvent mixtures: influence of uneven distribution of lipids after filtration and centrifugation.

Reasons for the variation in erythrocyte lipid extraction were investigated. We found that there was an uneven distribution of lipids after filtration (up to 10% accumulated in the filtrates) or centrifugation (up to 10% in the top fraction) of several apparently monophasic extraction systems. The uneven distribution was more pronounced in the systems containing relatively more water, or, generally speaking, with more nonpolar solvents. Ill-defined procedures using either filtration or centrifugation, therefore, could be the cause for variations in lipid extraction. A way to prevent the uneven distribution has been developed and is discussed.

1-Propanol↗
PubMed1995

Effect of a coffee lipid (cafestol) on regulation of lipid metabolism in CaCo-2 cells.

The influence of cafestol, a lipid component found in boiled coffee, on low density lipoprotein (LDL) and lipid metabolism was investigated in CaCo-2 cells cultured on filter membranes. The rate of uptake and degradation of 125I-labeled tyramine cellobiose-LDL was increased 50% in CaCo-2 cells incubated with cafestol (20 micrograms/ml, 63 microM) for 24 h, whereas in cells incubated with 25-hydroxycholesterol (10 micrograms/ml, 25 microM) the rate of uptake and degradation showed a 30% decrease. A mixture of kahweol and cafestol, both natural components of coffee beans, modestly enhanced the rate of LDL uptake and degradation, as compared to pure cafestol. Incubation of cafestol with CaCo-2 cells induced a 3-fold up-regulation of LDL receptor mRNA, as compared to control cells. In contrast, incubation of the cells with 25-hydroxycholesterol produced a 30% decrease of LDL receptor expression. CaCo-2 cells were transfected with a promoter region containing the sterol regulatory element-1 (SRE-1) coupled to the reporter gene chloramphenicol acetyltransferase (CAT). When cells transfected with SRE-1 promoter were incubated with cafestol, there was a 20% up-regulation of CAT activity, whereas 25-hydroxycholesterol abolished this activity. Cafestol contributed to a significantly lowered secretion of cholesteryl ester and triacylglycerol, regardless of the radiolabeled precursor used ([2-14C]acetic acid, [1,2,3-3H]glycerol, [3H]water, and [1-14C]oleic acid). This reduction in secretion of lipids was accompanied by an increase in trichloroacetic acid-soluble activity when radiolabeled oleic acid was used as a tracer. We conclude that cafestol promotes an enhanced rate of uptake and degradation of LDL, probably due to an increase in transcription of LDL receptor mRNA and a reduced secretion of cholesteryl ester and triacylglycerol in CaCo-2 cells.

Cell Line↗
PubMed1997

Redistribution of lipid probes at early stages of bilayer lipid membrane fusion.

Redistribution of hydrophobic probes (R18 and dipicrylamine DPA-) through a water gap between two bilayer lipid membranes (BLM) was studied. Both probes are widely used for monitoring lipid redistribution in different cell systems. The donor membrane loaded with the probe was brought into a close contact with the acceptor membrane, and the redistribution of the probe, was recorded as changes in the permittance of the acceptor membrane. It was shown that DPA- easily penetrated the water gap, whereas R18 was not detected in the acceptor membrane 30 min after the close contact formation. After fusion, R18 rapidly spread into the acceptor membrane; hence, only R18 reflects the behaviour of membrane lipids in the fusion process.

Electric Conductivity↗
PubMed1976

The lipid composition of cattle sebaceous glands: a comparison with skin surface lipid.

The lipid composition of isolated sebaceous glands from Ayrshire calves was compared with that of freshly secreted skin surface lipid. The sebaceous gland contained a higher proportion of phospholipid and unesterified fatty acid and a lower proportion of triglyceride; otherwise there was little difference in lipid composition between samples from the gland and the skin surface.

Animals↗
PubMed2003

Trans unsaturated fatty acids are less oxidizable than cis unsaturated fatty acids and protect endogenous lipids from oxidation in lipoproteins and lipid bilayers.

Epidemiological data suggest that dietary trans unsaturated fatty acids increase the risk of heart disease; however, the underlying mechanisms are unclear. In this study, we investigated one possible mechanism, namely, their effect on LDL oxidation. Supplementation of LDL with 10% 16:1 trans-cholesteryl ester (CE) inhibited the oxidation compared to that with 16:1 cis-CE. Total replacement of core lipids with 18:2 trans,trans-CE decreased the rate of LDL oxidation by 19% compared to replacement with 18:2 cis,cis-CE. When the surface phosphoglycerides were replaced with either 16:0-18:2 cis,cis-phosphatidylcholine (PC) or 16:0-18:2 trans,trans-PC, the latter was found to inhibit the rate and increase the lag time of oxidation to a greater extent than the former. To confirm these findings, we studied the oxidation of PC liposomes by assessing the formation of conjugated dienes or the degradation of a fluorescently labeled PC. By both methods, the 16:0-18:2 trans,trans-PC exhibited greater resistance to oxidation than the 16:0-18:2 cis,cis-PC. Eliminating the fluidity differences did not completely eliminate the differences in oxidation rates, suggesting that the trans double bond is inherently resistant to oxidation. The composition of the conjugated hydroperoxy products formed after oxidation differed markedly for the two 18:2 isomers. Supplementation of 16:0-18:2 cis,cis-PC liposomes with 20 mol % di16:1 trans-PC retarded oxidation rates to a greater extent than supplementation with di16:1 cis-PC. These studies show that dietary trans unsaturated fatty acids decrease the rate of lipid peroxidation, an effect that may mitigate the atherogenic effect of these fatty acids.

Alkadienes↗
PubMed1990

Effect of NO2 on lipids and lipid peroxidation in the CNS of the guinea-pig.

This study was undertaken to investigate the effect of nitrogen dioxide on some neurochemical parameters. Guinea-pigs were exposed to NO2, 5 p.p.m. and 10 p.p.m. for 2 hr daily for five weeks. The results showed significant depletion of the total lipids and phospholipids content of the cerebral hemisphere, cerebellum, midbrain and spinal cord following nitrogen dioxide intoxication. The results further revealed significant diminution in the cholesterol content of the NO2 intoxicated animals in cerebral hemisphere, cerebellum and midbrain. But on the other hand the level was significantly enhanced in the spinal cord. Interestingly, the rate of lipid peroxidation was found enhanced in all the investigated brain areas, and with increasing dosage the effect was correspondingly pronounced.

Animals↗
PubMedDate not supplied

[Effect of propofol and ketamine on lipid metabolism and lipid peroxidation in rats].

Ketamine (50 mg/kg, i.p.) increases the intensity of lipolysis in Wistar male rats, as manifested by increasing content of nonetherified fatty acids and cholesterol in the blood serum. This drug also enhances the lipid peroxidation (LPO) process, as manifested by the content of LPO products in the blood serum and in the liver and heart tissues. Propofol in the same dose also influences the lipid metabolism and LPO intensity, but to a lower extent.

Anesthetics↗
PubMedDate not supplied

[Indicators of lipid metabolism and lipid peroxidation system in patients with different types of lesions of the vessels of the lower limbs].

A total of 66 patients were investigated with IR imager and television capillaroscopy for the blood circulation in the vessels of low extremities as well as for the values of lipid metabolism and the system of lipid peroxidation. According to the status of the vascular system in the low extremities the examinees were divided into the groups with the normal status of the vascular system, the groups with the signs of venous insufficiency, microcirculatory disorders and atherosclerosis of major vessels. With the disorders of microcirculation in low extremities staged increments in the atherogenic shifts in the exchange were demonstrated. It was suggested that atherosclerotic changes in the arteries could be preceded with the hemodynamic changes in the venous and capillary systems due to rheological disorders due to the development of hypercoagulation which accompanied dyslipoproteinemias and other atherogenic shifts in the metabolism.

Arteriosclerosis↗
PubMed1998

Comparison of solution and crystal structures of maize nonspecific lipid transfer protein: a model for a potential in vivo lipid carrier protein.

The three-dimensional solution structure of maize nonspecific lipid transfer protein (nsLTP) obtained by nuclear magnetic resonance (NMR) is compared to the X-ray structure. Although both structures are very similar, some local structural differences are observed in the first and the fourth helices and in several side-chain conformations. These discrepancies arise partly from intermolecular contacts in the crystal lattice. The main characteristic of nsLTP structures is the presence of an internal hydrophobic cavity whose volume was found to vary from 237 to 513 A3 without major variations in the 15 solution structures. Comparison of crystal and NMR structures shows the existence of another small hollow at the periphery of the protein containing a water molecule in the X-ray structure, which could play an important structural role. A model of the complexed form of maize nsLTP by alpha-lysopalmitoylphosphatidylcholine was built by docking the lipid inside the protein cavity of the NMR structure. The main structural feature is a hydrogen bond found also in the X-ray structure of the complex maize nsLTP/palmitate between the hydroxyl of Tyr81 and the carbonyl of the lipid. Comparison of 12 primary sequences of nsLTPs emphasizes that all residues delineating the cavities calculated on solution and X-ray structures are conserved, which suggests that this large cavity is a common feature of all compared plant nsLTPs. Furthermore several conserved basic residues seem to be involved in the stabilization of the protein architecture.

Amino Acid Sequence↗
PubMed2004

Tea polyphenol epigallocatechin-3-gallate associates with plasma membrane lipid rafts: lipid rafts mediate anti-allergic action of the catechin.

High-affinity IgE receptor FcepsilonRI is key molecule in the IgE-mediated allergic reactions. Epigallocatechin-3-gallate (EGCG) has a suppressive effect of the expression of the FcepsilonRI. We show here that EGCG highly associates with plasma membrane microdomains, lipid rafts. The disruption of these lipid rafts caused a reduction of the amount of raft-associated EGCG and the FcepsilonRI -suppressive effect of EGCG. These results suggest that the interaction between EGCG and the lipid rafts is important for EGCG's ability to downregulate FcepsilonRI expression.

Antioxidants↗
PubMed1989

Phenotypic effects of apolipoprotein structural variation on lipid profiles. I. APO H and quantitative lipid measures in the healthy women study.

Apolipoprotein H (APO H), also known as beta 2-glycoprotein I, has been identified as a protein component of the major lipoprotein density fractions in human plasma. Recently, genetically determined structural polymorphism in white and black populations has been documented for this apolipoprotein. There are three common alleles in whites and blacks and a fourth allele found mainly in blacks. Family data confirm the autosomal codominant pattern of inheritance for the APO H structural gene. Little is known about the function of APO H, but it has demonstrated both lipid and platelet involvement. In this study we investigate the effect of APO H phenotypes on quantitative lipid measures in a group of 443 white women being followed through menopause for changes in cardiovascular risk. At baseline all women were premenopausal. None of the APO H phenotypes showed a statistically significant effect on lipid measures in this population.

Adult↗
PubMedDate not supplied

Enhanced in vitro and in vivo cationic lipid-mediated gene delivery with a fluorinated glycerophosphoethanolamine helper lipid.

BACKGROUND: One of the main drawbacks of synthetic, non-viral gene vectors is their relatively low in vivo efficiency when compared with viral vectors. The present paper describes the use of a partially fluorinated glycerophosphoethanolamine (F-PE), a close analog of DOPE, which, as a helper lipid with the cationic lipopolyamine pcTG90, increases its in vitro and in vivo gene transfer capability to a larger extent than DOPE. METHODS: To evaluate the contribution of F-PE to lipoplex-mediated gene transfer, the effect of including F-PE in lipoplexes formulated with the lipopolyamine pcTG90 for various pcTG90/DOPE/F-PE molar ratios [1:(1-x): x; 1:(2-y):y] was examined. For the in vitro analyses on human lung carcinoma epithelial A549 cells, the lipoplexes were formulated with the luciferase reporter plasmid pTG11033 using various N/P ratios (from 10 to 0.8, N = number of pcTG90 amines, P = number of DNA phosphates). The in vivo analyses were performed (1) with the luciferase reporter plasmid pCMV-Luc, which gives higher luciferase expression in the lung than pcTG11033; (2) with pcTG90/co-lipid(s) (1:2) lipoplexes which yield higher expression than the (1:1) formulations; and (3) by intravenous (iv) injection into the tail vein of mice. RESULTS: The efficiency of the F-PE lipoplexes to transfect in vitro A549 cells was significantly higher (5-90-fold) than that of DOPE lipoplexes, when formulated in HEPES. However, when formulated in 5% glucose, both co-lipids display a comparable transfection helper potential. Most remarkably, an up to eight-fold increase of luciferase expression could be measured in the lung after iv injection of pcTG90/F-PE (1:2) N/P 5 lipoplexes as compared with the pcTG90/DOPE lipoplexes. It led also to higher luciferase expression than PEI(ExGen500)/pCMV-Luc N/P 10 polyplexes. Besides expression in lung, low levels of luciferase expression were also observed in heart, spleen and liver. CONCLUSION: The present work, showing a higher in vitro and in vivo transfection potential for lipoplexes formulated with a partially fluorinated co-lipid as compared with its analogous DOPE lipoplexes or PEI polyplexes, indicates that 'fluorinated' lipoplexes are attractive candidates for in vivo applications.

Fluorine↗