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At least 1,063 records · Page 59Linked to original sources
PubMed1991

Effects of eicosapentaenoic acid on plasma lipoprotein subfractions and activities of lecithin:cholesterol acyltransferase and lipid transfer protein.

The effects of 12 weeks eicosapentaenoic acid (EPA) administration (2.7 g/day) on plasma lipoprotein subfraction levels and on activities of lecithin: cholesterol acyltransferase (LCAT) and lipid transfer protein (LTP) were investigated. Plasma VLDL-C, VLDL-TG, VLDL-PL, VLDL-apo B, VLDL-apo C-II and VLDL-apo C-III levels were decreased by 32.8% (P less than 0.05), 31.2% (P less than 0.01), 31.5% (P less than 0.05), 32.5% (P less than 0.05), 34.7% (P less than 0.05) and 34.1% (P less than 0.05), respectively. EPA did not change plasma IDL-TC, IDL-TG, IDL-PL and IDL-apo B levels. Plasma large, light LDL (LDL1)-TC, LDL1-PL and LDL1-apo B levels were decreased by EPA by 18.7% (P less than 0.02), 19.1% (P less than 0.01) and 23.3% (P less than 0.01) while LDL1-TG level was not changed. Plasma small, heavy LDL (LDL2)-TC level was increased by 25.7% (P less than 0.02) while LDL2-TG, LDL2-PL and LDL2-apo B levels were not altered. Plasma HDL2-TC, HDL2-TG, HDL2-PL and HDL2-apo A-I levels stayed unchanged by EPA treatment. EPA did not affect plasma HDL3-TC, HDL3-PL and HDL3-apo A-I levels but decreased HDL3-TG level significantly (P less than 0.02). LCAT activity was not altered by EPA. LTP activity was increased by 24.8% at 4 weeks (P less than 0.02) and by 32.1% (P less than 0.001) at 12 weeks EPA treatment. We conclude that EPA reduces plasma large, light LDL levels as well as plasma VLDL amounts and stimulates LTP activities.

Adult↗
PubMed1993

A DNA polymorphism for lecithin:cholesterol acyltransferase (LCAT) is associated with high density lipoprotein cholesterol concentrations in baboons.

We investigated the effects of a polymorphic PvuII site in the gene for lecithin:cholesterol acyltransferase (LCAT) on serum high density lipoprotein cholesterol (HDL-C) and apolipoprotein A-I (apo A-I) concentrations in a population of 750 pedigreed baboons. We also tested for genotype by diet interactions using data on HDL-C and apo A-I concentrations on two diets (chow and high-cholesterol, saturated fat). A significant (P < 0.001) association between the LCAT genotypes and HDL-C levels was observed. On both diets, animals homozygous for the less common allele had HDL-C levels that averaged 18-19% lower than animals homozygous for the more common allele. HDL-C levels of the heterozygotes were intermediate. The LCAT RFLP accounted for approximately 5% of the variation in HDL-C levels on the two diets. We observed no strong evidence for an LCAT genotype by diet interaction effect.

Alleles↗
PubMed1993

Copper- and malondialdehyde-induced modification of high density lipoprotein and parallel loss of lecithin cholesterol acyltransferase activation.

Incubation of high density lipoproteins (HDL) with 0.1-10 microM copper ions resulted in a decrease in tryptophan residues and a moderate diminution of lysine residues. Polymerization of apolipoprotein AI (apo A-I) was only observed for the highest concentration of Cu2+. A dose-dependent loss in lecithin cholesterol acyl-transferase (LCAT) activity was noted. Following incubation with 10 mM malondialdehyde, the physicochemical properties of HDL were more pronouncedly affected, in terms of lipid peroxidation products, relative electrophoretic mobility and percentages of intact tryptophan and lysine residues. Polymerization of apo A-I occurred after 40 min incubation, and a time-dependent loss of LCAT activation was noted. Since the deficiency in LCAT activation was observed in relatively mild conditions, when no perturbation of the physico-chemical properties of the particle could be shown, the determination of LCAT activity appears to be a sensitive test for HDL discrete modification.

Apolipoprotein A-I↗
PubMed1995

Lipoprotein pattern and plasma lecithin cholesterol acyl transferase activity in children with Alagille syndrome.

Alagille syndrome is frequently associated with hyperlipidemia and xanthoma. The aim of the study was to assess the lipid profile (plasma lipoproteins, apolipoproteins (apo)) and lecithin cholesterol acyl transferase (LCAT) activity, with and without treatment with cholestyramine in Alagille syndrome. Five children (mean age = 6 +/- 4 years) with Alagille syndrome were studied at two different times while receiving no treatment, and while receiving cholestyramine. They were compared with 12 normal controls, who were not different from patients for age and sex. In Alagille syndrome, total serum cholesterol, triglycerides and phospholipids were elevated compared with the controls (P < 0.008). VLDL-cholesterol, LDL-cholesterol, HDL-triglycerides, LDL-triglycerides and VLDL-phospholipids were higher, whereas HDL-cholesterol was lower than controls (P < 0.03). Apo B, CIII, E and lipoprotein particles Lp AI were higher (P < 0.001), whereas Lp AI:AII was lower than controls (P < 0.03). Lipoprotein-X was present in the 5 children with Alagille syndrome and explained in part the elevation of plasma cholesterol, phospholipids, and apo CIII. LCAT activity was decreased (P < 0.01) and might cause some abnormalities of HDL with lower cholesterol, higher triglycerides, apo E and apo CIII contents than controls, and abnormalities of VLDL and LDL with higher cholesterol, triglycerides, phospholipids and apo B contents than controls. Some of the risk factors of atherosclerosis were found in Alagille syndrome, namely high levels of plasma cholesterol, LDL cholesterol, apo B, apo B/apo AI. Treatment with cholestyramine resulted in a few modifications to the lipid profile, while lipoprotein-X and the decrease of LCAT activity persisted.

Adolescent↗
PubMed1994

Lipoprotein, lecithin:cholesterol acyl transferase and acetyl CoA carboxylase in stroke-prone spontaneously hypertensive rats fed a diet high in eicosapentaenoic acid.

To investigate the effect of dietary eicosapentaenoic acid (EPA) on plasma lipoprotein levels, lecithin:cholesterol acyltransferase (LCAT) activity and liver acetyl CoA carboxylase activity, highly concentrated EPA (78%) purified from sardine oil was fed to stroke-prone spontaneously hypertensive rats (SHRSP) for 30 days. Significantly (P < 0.05) lower systolic blood pressure and plasma total cholesterol were observed in rats fed an EPA diet. In addition, higher HDL cholesterol and lower VLDL cholesterol levels were found in rats fed the EPA diet as compared with rats fed the control diet. However, no significant change of plasma LDL cholesterol was observed in rats between the two dietary groups. EPA supplementation increased the activity of plasma LCAT in rats. In addition, rats fed an EPA diet had lower liver total lipids and adipose tissue weights. However, higher liver acetyl CoA carboxylase activity was observed in rats fed the EPA diet. Results from the present study suggest that dietary EPA might stimulate the plasma lipoprotein metabolism and also alter lipogenesis in the liver of SHRSP rats.

Acetyl-CoA Carboxylase↗
PubMed1994

Effects of alcohol on lipoprotein lipase, hepatic lipase, cholesteryl ester transfer protein, and lecithin:cholesterol acyltransferase in high-density lipoprotein cholesterol elevation.

The mechanism whereby alcohol increases high-density lipoprotein cholesterol (HDL-C) levels is unclear. Lipoprotein lipase (LPL), hepatic lipase (HL), cholesteryl ester transfer protein (CETP) and lecithin:cholesterol acyltransferase (LCAT) act on lipoprotein metabolism. The purpose of the present study is to determine which one or what combination of these factors is responsible for the rise in HDL-C levels following alcohol ingestion. After 3 weeks of abstinence, 12 men consumed 0.5 g/kg bw of alcohol per day for 4 weeks; 13 abstaining men served as controls. Mean plasma total cholesterol (TC) levels were unchanged in either group throughout the study. Among the alcohol consumers, plasma triglycerides (TG), HDL-C, apolipoprotein (apo) A-I and A-II levels increased significantly after 3 weeks of alcohol loading but were unchanged in the control group. High-density lipoprotein3 cholesterol (HDL3-C) levels increased significantly in the alcohol consumers after 4 weeks of alcohol loading whereas high-density lipoprotein2 cholesterol (HDL2-C) levels were unaffected. In the controls, neither HDL2-C nor HDL3-C changed significantly. Post-heparin plasma (PHP) LPL activity and mass increased significantly (P < 0.01) after the alcohol ingestion (controls remained unchanged) without changing LPL specific activity. HL, CETP and LCAT activities were unaffected in both groups. We conclude that of the factors considered, LPL contributed the most to the alcohol-induced rise in HDL-C.

Adult↗
PubMed1993

Delayed matching-to-sample performance during a double-blind trial of tacrine (THA) and lecithin in patients with Alzheimer's disease.

During a double blind, inpatient-outpatient study of THA (tacrine) and lecithin in Alzheimer's disease, data on a laboratory-based delayed-matching-to-sample (DMS) test was collected on six of 10 subjects. DMS measures proved more sensitive to drug effects than clinical measures of cognitive performance. Both clinical and DMS measures suggest that patients with mild to moderate impairment are more likely to show modest improvement in performance than advanced cases. Outcome measures are related to possible mechanisms of attention and memory.

Aged↗
PubMed1981

Plasma lipid concentrations and lecithin:cholesterol acyltransferase activity in normolipidemic subjects given fenofibrate and colestipol.

Plasma lipids and lipoprotein cholesterol concentrations and lecithin:cholesterol acyltransferase activity were measured in 7 normolipidemic subjects before, and 7 days after, the administration of fenofibrate (300 mg daily) and colestipol (15 g daily) taken separately or simultaneously. Fenofibrate provoked a significant decrease in the mean plasma triglycerides (26%) and cholesterol (10%) concentration; only plasma cholesterol concentrations were significantly lowered by colestipol (26%). The cholesterol lowering effects of the two drugs were additive as was observed when colestipol was added to fenofibrate. The mean plasma high density lipoprotein cholesterol (HDL-C) concentration was significantly increased by fenofibrate (10%) and when colestipol was added to fenofibrate (15%), but not by colestipol alone. Both fenofibrate and colestipol caused significant reduction of the mean plasma low density lipoprotein cholesterol (LDL-C) concentration and the mean plasma LDL-C/HDL-C ratio (13% and 18%, respectively, with fenofibrate, 44% and 52% with colestipol, and 53% and 62% with colestipol added to fenofibrate). The mean plasma fractional esterification rate was significantly increased by 25% and 12%, respectively, with fenofibrate and colestipol when taken separately, and still more (91%) when colestipol was added to fenofibrate. The mean plasma molar esterification rate was significantly lowered by colestipol, but remained unchanged with the other drug regimens. This study shows that fenofibrate and colestipol given to normolipidemic subjects can induce in a very short period of time (7 days) marked changes in lipoprotein metabolism. Interpretations of the findings in relation to lipoprotein metabolism are discussed.

Adult↗
PubMed1989

Low-dose colestipol plus fenofibrate: effects on plasma lipoproteins, lecithin:cholesterol acyltransferase, and postheparin lipases in familial hypercholesterolemia.

Effects on plasma lipoproteins, lecithin:cholesterol acyltransferase (LCAT), and postheparin lipase (LPL and HTGL) activities were studied in 18 patients with familial hypercholesterolemia during 8-week treatment periods with colestipol (15 g/d), fenofibrate (0.25 g/d), and colestipol plus fenofibrate. Lipoprotein lipids and apolipoproteins were determined by standard procedures, LCAT by a self-substrate method, and lipases by nonradioisotopic methods. Colestipol and fenofibrate, each given independently, caused similar percentage decreases in LDL cholesterol and apolipoprotein B: -18.4% and -8.6% v -17.4% and -10.6% Colestipol increased the VLDL cholesterol concentration, whereas fenofibrate reduced this parameter but increased HDL cholesterol and apolipoprotein A-I levels. The combination of both drugs led to a substantial fall in LDL cholesterol (-36.8%) and in apolipoprotein B (-28.3%) and maintained the other effects of fenofibrate on VLDL and HDL. Colestipol, given independently or with fenofibrate, produced an increase of the fractional esterification rate of the LCAT enzyme (+25.3% and +36.2%). Fenofibrate stimulated the postheparin LPL enzyme by +16.1% and +21.7%, respectively. This study indicates the complementarity in effectiveness when both drugs were administered together. The appropriate reduction in LDL was combined with the favorable effects on HDL in familial hypercholesterolemia.

Adolescent↗
PubMed1993

Lecithin-cholesterol acyltransferase and lipid transfer protein activities in liver disease.

The activities of lecithin-cholesterol acyltransferase (LCAT) and lipid transfer protein (LTP) were assayed using sensitive radioassay methods in controls (n = 113) and in patients with various liver diseases (n = 72). Plasma LCAT activity decreased with progression of hepatocellular damage. Plasma LTP activity in controls was 216 +/- 68 nmol/mL/h, and there were no significant differences between controls and patients with chronic hepatitis ([CH], 193 +/- 70), compensated liver cirrhosis (LC) with or without hepatocellular carcinoma ([HCC], 197 +/- 48 and 193 +/- 62, respectively), or decompensated liver cirrhosis ([dLC], 182 +/- 65). In acute viral hepatitis, LTP activity decreased significantly; however, the degree of reduction was not as dramatic as that for LCAT. There was no correlation between LCAT and LTP activity both in controls and patients with various liver diseases. LCAT activity was positively correlated with serum albumin (r = .52, P < 0.1) and cholinesterase (r = .37, P < .01) levels, and inversely correlated with serum bilirubin level (r = -.38, P < 0.1); there was no correlation between plasma LTP activity and these parameters of liver function. That plasma LTP activity did not change with hepatocellular damage may indicate that the liver in humans may not be the primary site of LTP production.

Acute Disease↗
PubMed1989

Separation of free and apolipoprotein D-associated human plasma lecithin: cholesterol acyltransferase.

A high performance gel filtration method for the rapid and reproducible separation of free and apolipoprotein D-associated lecithin: cholesterol acyltransferase (LCAT) originating from human plasma has been developed. Starting from step 3 of a previously invented covalent chromatography procedure, free LCAT was obtained as a well separated fraction in a yield of 55% of that injected into the column. The free LCAT had a specific activity of over 34,000 units/mg and did not contain apolipoprotein D or any other contaminant in the injected sample. Further 28% of LCAT with fully retained activity was recovered in a second fraction, demonstrating a 66,000 u LCAT associated with all apolipoprotein D occurring as a mean 33,000 u and a minor 66,000 u species and with at least two unidentified proteins with apparent molecular masses of 76,000 u and 43,000 u, respectively. Both free and apolipoprotein D-associated LCAT accepted the free cholesterol of heat-inactivated plasma selectively depleted of VLDL and LDL (alpha-LCAT activity) and of HDL (beta-LCAT activity) as substrate.

Apolipoproteins↗
PubMed1987

The isolation and characterisation of cDNA and genomic clones for human lecithin: cholesterol acyltransferase.

The protein sequencing of tryptic peptides from purified human lecithin: cholesterol acyltransferase (LCAT) identified sufficient amino-acid sequence to construct a corresponding mixed oligonucleotide probe. This was used to screen an adult human cDNA liver library, from which incomplete cDNA clones were isolated. The DNA sequence of these clones allows the prediction of the entire amino-acid sequence of the mature LCAT enzyme. The mature protein consists of 416 amino acids and contains several marked stretches of hydrophobic residues and four potential glycosylation sites. The cDNA probe detects LCAT mRNA sequences approx. 1500 bases long in human liver, but not intestine, RNA. The cDNA probe was used to isolate LCAT genomic recombinants from a human genomic library. Southern blotting data, and restriction site mapping, suggest that there is a single human LCAT structural gene between 4.3 and 5.5 kb in size.

Amino Acid Sequence↗
PubMed1996

Inhibition by lecithin-bound iodine (LBI) of inducible allergen-specific T lymphocytes' responses in allergic diseases.

In atopic patients, allergen-sensitized T lymphocytes specifically proliferate in the presence of T cell-growth factor, interleukin 2 (IL-2). Lecithin-bound iodine (LBI), which has been used as a therapeutic modality for patients with bronchial asthma (BA), effectively inhibited Dermatophagoides farinae (Df) mite antigen-induced IL-2 responsiveness in concentrations comparable to LBI concentrations in blood. IL-2-responding T cells were more sensitive to LBI than antigen-presenting cells, whereas LBI suppressed the release of interleukin 1 (IL-1) elicited by Df antigen. In addition, ovalbumin (OVA)-induced IL-2 responsiveness in egg sensitive patients and purified protein-derivative (PPD)-induced IL-2 responsiveness were similarly inhibited by LBI. The IL-2 responsiveness induced by concanavalin A (Con A), however, was not changed. On the basis of these results, LBI may act as a slight immunosuppressant to inhibit the induction of allergen-specific lymphocytes and to improve the clinical status in allergic diseases.

Adult↗
PubMed1979

Motion of the lengthened zwitterionic head groups of C16-lecithin analogues in aqueous solutions as studied by dielectric relaxation measurements.

Phosphatidyl choline analogues with increased phosphate-trimethylammonium distance were synthesized and aqueous solutions of these bilayer forming phospholipids were prepared. Dielectric spectra of the solutions were measured at several temperatures around the crystalline/liquid-crystalline phase transition temperature of the samples. The observed data are treated in terms of a Debye relaxation function and also of a relaxation function based on a theoretical model of the aqueous solutions of multibilayer vesicles. As a noteworthy result, a pronounced cooperativity effect in the diffusive motions of the zwitterionic head groups emerges. The degree of cooperativity depends on the radius of curvature of the multibilayer vesicles and also on the length of the phospholipid zwitterions. The values for the mobility of the trimethylammonium group are of the same order of magnitude as those for the mobility of whole phospholipid molecules in its lateral diffusive motion. Indications for a phase transition at a temperature above the main transition temperature are found with solutions of C16- lecithin analogues with 9 and 10 methylene groups between the phosphate and the trimethylammonium group.

Journal Article↗
PubMed1991

Reduction of the in vitro hemolytic activity of soybean lecithin liposomes by treatment with a block copolymer.

The in vitro hemolytic activity of liposomes made of soybean L-alpha-lecithin towards diluted (0.0086 v/v) human erythrocytes was used to investigate the effect of surface coating on the interaction of liposomes with cells. The increase in apparent volume of the block copolymer of ethylene glycol and propylene glycol, Pluronic F-127, in the presence of liposomes supports the hypothesis of either adsorption or penetration of the copolymer at the surface of the liposomes. When the liposomes are pre-incubated with Pluronic F-127, their lytic activity towards fresh erythrocytes is significantly reduced while it remains unchanged towards erythrocytes aged in vitro. It is also found that aging the liposomes has little effect on their lytic activity while aging of the erythrocytes makes them more fragile towards the liposomes. The results are discussed in terms of steric hindrance.

Erythrocytes↗
PubMed1992

Anthracycline gels. II. Spectroscopic study on doxorubicin-lecithin association products.

Thixotropic and thermally reversible gels have been prepared from doxorubicin-lecithin association products (DL12) by addition of salts to their aqueous solutions. The gel formation and the melting profiles have been followed by several spectroscopic techniques (1H NMR, UV-Vis, Circular Dichroism). The transition temperatures increase as the concentration of both the salt and the DL12 is increased, suggesting a progressive closer approach of the gel forming species. The process of the gel formation is cooperative and causes immobilization of the doxorubicin molecules of DL12.

Circular Dichroism↗
PubMed1981

Electrical membrane phenomena in spherules from proteinoid and lecithin.

Spontaneous and induced electrical phenomena resembling membrane and action potentials in natural excitable cells have been observed in artificial cells. These artificial cells were made from thermal proteinoid and lecithin in a solution of potassium acid phosphate with glycerol.

Electric Conductivity↗
PubMed1986

D-galactosamine induced hepatitis in the rabbit: effect on lecithin:cholesterol acyltransferase activity, plasma lipid transfer protein activity and high density lipoproteins.

Hepatitis was induced in rabbits by a single intraperitoneal injection of D(+)-galactosamine-HCl (750 mg/kg body wt). Plasma lecithin:cholesterol acyltransferase activity fell to 5% and lipid transfer protein activity to 50% of control values 48 hr after injection. Discoid high density lipoprotein began to appear in plasma of treated rabbits 36 hr after injection, along with populations of high density lipoprotein (HDL) which were both smaller (radius 3.7 nm) and larger (radius 5.9 nm) than the original HDL population (radius 4.8 nm).

Alanine Transaminase↗