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PubMed2000

Histamine induced decrease of lecithin levels in broncho-alveolar lavage fluid of rats is mediated by H2 receptor.

Lecithin, a major surface active substance of the surfactant system of the lung, was estimated in broncho-alveolar lavage (BAL) fluid in four groups of healthy adult male albino rats. Rats from group I were not administered any drug and acted as controls. Group II were administered histamine diphosphate. Group III were given H1 blocker (pyrilamine maleate) followed by histamine diphosphate. Group IV received H2 blocker (ranitidine hydrochloride) followed by histamine diphosphate. Lecithin content of BAL fluid in the control group was compared with that in the other three groups. A significant decrease in lecithin content was observed in the rats that received either histamine diphosphate or H1 blocker followed by histamine diphosphate. However, compared to control rats no significant difference in lecithin content was seen in rats that received H2 blocker followed by histamine diphosphate. The results clearly indicate that the decrease in surface active lecithin content in BAL fluid following administration of histamine diphosphate was unaffected by prior administration of H1 blocker, but was blocked by prior administration of H2 blocker. It was concluded that histamine induced decrease in lecithin content of BAL fluid is mediated through H2 receptors. Since the predominant source of intra-alveolar lecithin are Type II cells of the alveolar epithelium, It is possible that Type II cells have H2 receptors, stimulation of which resulted in decreased intraalveolar lecithin.

Animals↗
PubMed2003

Double-blind, randomized, controlled study on the efficacy and safety of a novel diclofenac epolamine gel formulated with lecithin for the treatment of sprains, strains and contusions.

To evaluate the efficacy of the new diclofenac-N-(2-hydroxyethyl)-pyrrolidine gel formulated with lecithin (DHEP lecithin) compared with diclofenac-N-(2-hydroxyethyl)-pyrrolidine gel (DHEP gel) without lecithin in mild-to-moderate posttraumatic injuries (grade 1 ankle, knee and muscle injuries), a multicenter, double-blind, controlled study was carried out. A total of 100 patients were enrolled and randomly assigned to either DHEP lecithin (n = 52) or DHEP gel (n = 48) treatment. All patients concluded the treatment period except for five, who did not turn up to their respective investigational sites for the follow-up visits. According to an intention-to-treat approach, they were all included in the statistical analysis. As for the efficacy and safety analysis, the primary variable was "pain on movement" as measured by a Huskisson visual analog scale. During the first 3 days of treatment each group recorded a significant within-group decrease, but patients treated with DHEP lecithin showed a decrease in absolute value that was statistically greater than that obtained with DHEP gel (p = 0.025). At the end of the treatment period (day 10) the difference between groups was still statistically significant (p = 0.036). The statistical analysis of the secondary efficacy variables showed significant results in favor of DHEP lecithin treatment. These were superimposable on the results found for the primary variable. The global efficacy and tolerability judgments, reported either by patient or by physician, showed no statistical difference between treatment groups. Due to the presence of lecithin in the new gel formulation, DHEP lecithin showed a faster and significantly more marked therapeutic effect compared with that of DHEP gel.

Acetaminophen↗
PubMed2005

Analgesic efficacy of a lecithin-vehiculated diclofenac epolamine gel in shoulder periarthritis and lateral epicondylitis: a placebo-controlled, multicenter, randomized, double-blind clinical trial.

Diclofenac epolamine (2-hydroxyethyl-pyrrolidine) (DHEP) is a diclofenac salt endowed with enhanced cutaneous permeation. To optimize its absorption after topical application, a lecithin-enriched DHEP 1.3% gel has been developed (DHEP lecithin gel) and investigated in patients with shoulder periarthritis and lateral epicondylitis in a placebo-controlled, multicenter double-blind clinical trial. One hundred fifty-eight patients were randomized to a 10-day treatment with DHEP lecithin gel or placebo (5 g t.i.d. applied on the painful area). The efficacy criteria were pain measured by visual analog scale (VAS) while performing a specific standardized movement, intake of rescue medication (paracetamol), and the disabilities of the arm, shoulder and hand (DASH) questionnaire. VAS scores indicated a consistently higher analgesic activity of DHEP lecithin gel. At day 3, pain was reduced by -20.1 +/- 20.2 and -9.9 +/- 12.7 mm in the DHEP lecithin gel- and placebo-treated patients, respectively (p < 0.001); at day 6 of treatment, DHEP lecithin gel induced a pain reduction of -33.2 +/- 26.1 mm, while the reduction achieved with placebo was only -21.2 +/- 18.8 mm (p < 0.001). The mean changes in DASH questionnaire indicated that DHEP lecithin gel was more effective than placebo in improving patient well-being and reducing difficulties in performing the activities most severely impaired by rheumatism, while no difference was observed between the two treatments in consumption of rescue medication. In conclusion, these results indicate that DHEP lecithin gel is a topically effective analgesic product in patients with shoulder periarthritis or lateral epicondylitis and provide further evidence on the use of topical nonsteroidal anti-inflammatory drugs as an optimal approach to the treatment of localized musculoskeletal disorders.

Analgesics↗
PubMed1967

The ionic structure of lecithin monolayers.

Surface potentials of mixed monolayers of dicetyl phosphate and eicosanyl trimethylammonium bromide (1:1) were the same on subsolutions of 0.02 M NaCl or 0.01 M CaCl(2), which indicated that ionic phosphate does not interact with Ca(++) in the presence of a neighboring trimethylammonium group. Surface potential-pH plots of dicetyl phosphate, and of dipalmitoyl, egg, and dioleoyl lecithins showed that as the pH of the subsolution is decreased the phosphate groups in the monolayer are neutralized in the order: dicetyl phosphate > dipalmitoyl lecithin > egg lecithin > dioleoyl lecithin. The binding of cations (Na(+), Ca(++)) to the phosphate group of lecithin also showed the same order. The binding of Ca(++)) to egg phosphatidic acid monolayers, as measured by the increase in surface potential, is considerably greater than that to egg lecithin. These results suggest that there is an internal salt linkage between the phosphate and trimethylammonium groups on the same lecithin molecule. An increase in unsaturation of fatty acyl chains increases the intermolecular spacing, which reduces the ionic repulsion between polar groups, and hence strengthens the internal salt linkage. The results support the concept of a vertical rather than coplanar orientation of the phosphoryl choline group with respect to the interface. A position has been proposed for Ca(++) in the dipole lattice of lecithin from a consideration of the surface potential measurements.

Calcium↗
PubMed1982

Origin of biliary cholesterol and lecithin in the rat: contribution of new synthesis and preformed hepatic stores.

The contribution of de novo synthesis to the secretion of cholesterol and lecithin in bile was assessed in isolated rat livers, perfused with a lipid-free medium. Cholesterol and lecithin synthesis were measured by the incorporation of tritiated water and [14C]-choline, respectively. Taurocholate stimulated the secretion of biliary lipids to the same extent in perfused livers and in live rats. During the first hour of perfusion, and when hepatic synthesis was active, newly synthesized cholesterol accounted for about 10% of biliary cholesterol and newly synthesized lecithin for 3% of biliary lecithin. Fasting reduced the contribution of newly synthesized cholesterol in bile to less than 1% but did not change the rate of biliary cholesterol secretion. After 2 hours of perfusion, newly synthesized biliary cholesterol accounted for only 4% of total hepatic sterol synthesis. Biliary lecithin, synthesized hepatic lecithin. We conclude that new synthesis makes only a small contribution to biliary cholesterol and lecithin secretion, and that, in the absence of perfusate lipids, both biliary cholesterol and lecithin must be predominantly mobilized from a preformed hepatic pool.

Animals↗
PubMed1981

Lecithin:cholesterol acyltransferase (LCAT) mass; its relationship to LCAT activity and cholesterol esterification rate.

The relationship between plasma lecithin:cholesterol acyltransferase mass and enzyme activity and between mass and plasma cholesterol esterification rate was determined in 25 adult volunteers without overt disease (14 normolipidemic and 11 hyperlipidemic). Furthermore, the relationship of lecithin:cholesterol acyltransferase mass and cholesterol esterification rate to lipids, apoproteins, age, and ideal body weight was assessed. Lecithin:cholesterol acyltransferase mass determined by radioimmunoassay was highly correlated with enzyme activity assayed using a heated plasma substrate (r = 0.636) and with the molar cholesterol esterification rate determined either by radioassay (r = 0.809) or by measurement of the decrease of unesterified cholesterol (r = 0.621). Lecithin:cholesterol acyltransferase mass was also positively correlated with total cholesterol (r = 0.608), unesterified cholesterol (r = 0.562), age (r = 0.544), and percent ideal body weight (r = 0.619), but was not significantly correlated with log triglyceride, high density lipoprotein cholesterol, or apolipoproteins A-I, A-II, or D. Plasma cholesterol esterification rate by both methods was highly positively correlated with total cholesterol, unesterified cholesterol, log triglyceride, and age, but was inversely correlated with high density lipoprotein cholesterol. Upon partial correlation analysis with lecithin:cholesterol acyltransferase mass kept constant the cholesterol esterification rate remained significantly positively related to total cholesterol, unesterified cholesterol, and log triglyceride and inversely related to high density lipoprotein cholesterol. Two subjects had normal lecithin:cholesterol acyltransferase but approximately half normal molar cholesterol esterification rate. Measurement of lecithin:cholesterol acyltransferase mass and activity along with plasma cholesterol esterification rate will permit differentiation of abnormalities of enzyme from qualitative or quantitative substrate or cofactor abnormalities. Also, the finding that the regression line between LCAT mass and the plasma esterification rate by direct determination of unesterified cholesterol passes through the origin suggests that all immunodetectable LCAT in plasma is active in normal subjects.-Albers, J. J., C-H. Chen, and J. L. Adolphson. Lecithin:cholesterol acyltransferase (LCAT) mass; its relationship to LCAT activity and cholesterol esterification rate.

Adult↗
PubMed1981

New method for determining lecithin and sphingomyelin in amniotic fluid.

We describe a new method of complete analysis for lecithin, lysolecithin, and sphingomyelin in amniotic fluid. The analysis is based on alkaline hydrolysis of the lecithins and the enzymic hydrolysis of sphingomyelin. The choline formed in each instance is enzymically phosphorylated with [gamma-32P]ATP to yield [gamma-32P]phosphorylcholine, which is isolated by anion-exchange chromatography and shown to be stoichiometrically related to lecithin, lysolecithin, and sphingomyelin. Other phospholipids do not interfere. Using this methodology, we developed three potential approaches to the assessment of fetal lung maturity: the ratio of lecithin plus lysolecithin (total lecithin) to sphingomyelin, the total lecithin concentration, and total lecithin as a percentage of total amniotic fluid phospholipids. All three indices were compared with the lecithin/sphingomyelin ratio obtained by a chromatographic procedure. Our data suggest that measuring the percentage of total lecithin may provide the best means of evaluating fetal lung maturity, but a final judgment must await clinical investigation.

Amniotic Fluid↗
PubMed1985

Defective enzyme causes lecithin-cholesterol acyltransferase deficiency in a Japanese kindred.

Lecithin-cholesterol acyltransferase mass levels and activity and apolipoproteins A-I, A-II, B and D were measured in a Japanese family who have a familial lecithin-cholesterol acyltransferase deficiency. This analysis was performed to gain insight into the molecular basis of the enzyme deficiency and to compare findings in this family with other families with familial lecithin-cholesterol acyltransferase deficiency. The mass of the enzyme in plasma was determined by a sensitive double antibody radioimmunoassay, and enzyme activity was measured by using a common synthetic substrate comprised of phosphatidylcholine, cholesterol and apolipoprotein A-I liposomes prepared by a cholate dialysis procedure. The lecithin-cholesterol acyltransferase-deficient subject had an enzyme mass level that was 35% of normal (2.04 micrograms/ml, as compared with an average normal level of 5.76 +/- 0.95 micrograms/ml in 19 Japanese subjects) and an enzyme activity of less than 0.1% of normal (0.07 nmol/h per ml, as compared with normal levels of 100 nmol/h per ml). This subject also had lower levels of apolipoproteins: apolipoprotein A-I was 53 mg/dl (42% of normal), apolipoprotein A-II was 10.6 mg/dl (31% of normal), apolipoprotein B was 68 mg/dl (68% of normal), and apolipoprotein D was 3.6 mg/dl (60% of normal). The three obligate heterozygotes had enzyme mass levels ranging from 65% to 100% of normal and enzyme activity levels ranging from 23% to 65% of normal (23.4, 56.8, and 64.7 nmol/h per ml, respectively). The proband's sister had an enzyme mass level of 6.55 micrograms/ml (114% of normal) and an enzyme activity of only 64.8 nmol/h per ml (65% of normal), suggesting that she was also a heterozygote for lecithin-cholesterol acyltransferase deficiency. The obligate heterozygotes and the sister had normal apolipoprotein levels. We conclude that the lecithin-cholesterol acyltransferase deficiency in this family is due to the production of a defective enzyme that is expressed in the homozygote as well as in the heterozygotes, and, further, that this family's mutation differs from that reported earlier for other Japanese lecithin-cholesterol acyltransferase-deficient families.

Female↗
PubMed1998

Molecular diagnosis of lecithin: cholesterol acyltransferase deficiency in a presymptomatic proband.

We report the molecular diagnosis of a lecithin : cholesterol acyltransferase deficiency in a 12-year old proband with a high-density lipoprotein deficiency. The increased percentage of free cholesterol in plasma and high-density lipoprotein indicated an inherited lecithin : cholesterol acyltransferase deficiency as the underlying cause. This diagnosis was confirmed by a low plasma lecithin : cholesterol acyltransferase activity and a combination of genetic analyses which demonstrated compound heterozygosity for two mutations in the lecithin : cholesterol acyltransferase gene of the proband. One was a previously unreported 2 bp deletion leading to a stop signal in codon 77 and the other a point mutation causing Arg 135-->Gln transition. To our knowledge, this is the first diagnosis of lecithin : cholesterol acyltransferase deficiency in a pre-symptomatic patient. Whether the proband will develop signs of complete lecithin : cholesterol acyltransferase deficiency or the milder form (Fish Eye Disease) is uncertain, although the former possibility is more likely. The risk of premature atherosclerosis conferred by lecithin : cholesterol acyltransferase deficiency is not well established. The proband will need to be carefully monitored in the future.

Child↗
PubMed1996

In vivo uptake of lecithin-coated polystyrene beads by rat hepatocytes and sinusoidal endothelial cells.

BACKGROUND: While phagocytosis by Kupffer cells (stellate perisinusoidal macrophages) is well known and that by endothelial cells also is thought to occur under certain conditions, the uptake of large particles by hepatocytes has not been well studied. We reported previously the selective phagocytic uptake of material by hepatocytes using egg lecithin-coated silicon particles. In the present work, we describe more precisely this process following the injection of lecithin-coated polystyrene beads. Additionally, we consider the possible significance of the transcytotic action by endothelial cells. METHODS: Polystyrene latex beads (240 nm in diameter) composed of two layers of polystyrene and methyl methacrylate with a central void cavity and diameter of 140 nm were injected into male Wister-Imamichi rats. The injections were administered through the hepatic portal vein in a volume of 3 ml (concentration of the lecithin-coated or uncoated beads was 2 mg/ml). Controls received the lecithin alone at a concentration of 2 mg/ml. Liver samples were taken 5, 10, or 15 min after injection, fixed, and processed for ultrastructural analysis. RESULTS: Both lecithin-coated and noncoated beads were mainly incorporated in the Kupffer cells as well as in the endothelial cells. Bristle-coated invaginations were observed in the uptake by both cell types; however, noncoated invaginations were also active in the endothelial cells, especially on the surface facing the perisinusoidal space of Disse. Only coated beads were observed within the space or in the hepatocytes. Once taken up by the hepatocytes, the lecithin-coated beads were found either within lysosomes or in a free state in the cytoplasm. CONCLUSIONS: Uptake of 240 nm lecithin-coated polystyrene beads was observed by Kupffer cells, endothelial cells and hepatocytes. These beads were considered to be transported across the endothelial cells by transcytosis. Pseudopodia and bristle-coated invaginations were not employed by the hepatocytes when incorporating the beads.

Animals↗
PubMed1998

Diurnal pattern of choline concentrations in serum of pigs as influenced by dietary choline or lecithin intake.

Athletes especially experience a significant decrease in plasma choline concentrations during exercise which can be compensated in part by consumption of lecithin, a natural source of choline. In addition, the effect of lecithin on plasma choline concentrations in humans is obviously considerably greater and more prolonged than that of an equivalent amount of choline salts. Serum choline acts as a precursor for the synthesis of acetylcholine, which, in turn, acts as a neurotransmitter. The effect of dietary choline derived from either choline chloride or lecithin on the diurnal pattern of free choline concentrations in serum was studied using the pig as a potential model for humans. Six barrows, average initial body weight 120 kg, were fitted with permanent catheters in the jugular vein to determine the diurnal pattern of serum choline concentrations as affected by dietary choline or lecithin intake. The pigs were fed two semi-purified diets twice daily (1,500 g each meal) that contained corn, casein and a mineral-vitamin premix supplemented with equal amounts of choline (480 mg/kg) from either choline chloride or lecithin (BIOFOSFATIN). The diets supplemented with choline were fed at 08.00 h in the morning and the experiment was carried out according to a 3 x 2 cross-over design. All pigs received the basal diet that contained 450 mg/kg choline at the evening feeding (20.00 h). Following an adaptation period of 6 d, blood was collected on d 7; 0.5 h before the morning feeding and 1, 2, 4, 6, 8, 10 and 12 h postprandially. The determination of serum choline concentrations was carried out by tandem-mass spectroscopy. There were no differences (p > 0.05) between the two diurnal patterns of the serum choline concentrations. Both diurnal patterns showed a postprandial peak at 0.5 h (2.71 mg/l for choline chloride and 2.35 mg/l for lecithin supplementation) and decreased after 2 h postprandially to the preprandial concentrations. In conclusion, there were no differences (p > 0.05) in the diurnal patterns of serum choline concentrations in pigs after consumption of dietary choline chloride or lecithin, which is in contrast to corresponding studies in humans.

Animal Feed↗
PubMed1985

Lecithin:cholesterol acyltransferase regulation. Effect of fluidity of dimyristoylphosphatidylcholine vesicles.

The regulation of lecithin:cholesterol acyltransferase by changes in phospholipid bilayer fluidity was investigated using pyrene excimer fluorescence to measure fluidity. Fluidity of dimyristoylphosphatidylcholine (DMPC) unilamellar vesicles was decreased by the addition of up to 20% (mol/mol) cholesterol and increased by the addition of up to 10% (mol/mol) lysoDMPC. When both cholesterol and lysoDMPC are present in the bilayer, their individual effects on fluidity are altered. These changes can be explained by complex formation between cholesterol and phospholipid as in the model of Presti et al. (Presti, F.C., Pace, R.J. and Chan, S.I. (1982) Biochemistry 21, 3831-3335). Lecithin:cholesterol acyltransferase activity with these vesicles as substrates was measured to determine whether activity can be modulated by the fluidity changes of the bilayer on which the enzyme acts. When 10% lysoDMPC, a known lecithin:cholesterol acyltransferase inhibitor, is added to the vesicles, inhibition of activity is observed. When 7.5% lysoDMPC is added to vesicles which contain either 5 or 10% cholesterol, lecithin:cholesterol acyltransferase activity increases. This increase in lecithin:cholesterol acyltransferase activity due to vesicle-fluidity increase is sufficient to overcome the decrease in activity due to lecithin:cholesterol acyltransferase inhibition. This is the first report of the ability of lysoDMPC to increase lecithin:cholesterol acyltransferase activity.

Cholesterol↗
PubMed1987

Aromatic boronic acids as probes of the catalytic site of human plasma lecithin-cholesterol acyltransferase.

We have recently proposed a catalytic mechanism for human plasma lecithin-cholesterol acyltransferase (EC 2.3.1.43) (J. Biol. Chem. (1986) 261, 7032-7043), implicating single serine and histidine residues in phosphatidylcholine cleavage and two cysteine residues in cholesterol esterification. We now confirm the involvement of serine and histidine in catalysing the phospholipase A2 action of lecithin-cholesterol acyltransferase by demonstrating the inhibition of this activity by phenylboronic acid (Ki = 1.23 mM) and m-aminophenylboronic acid (Ki = 2.32 mM), inhibitors of known serine/histidine hydrolases. The specificity of the interaction of aromatic boronic acids with catalytic serine and histidine residues and the putative formation of a tetrahedral adduct between boron and the lecithin-cholesterol acyltransferase serine hydroxyl group which is similar to the transition-state intermediate formed between phosphatidylcholine and the catalytic serine residue was suggested by: substrate protection against inhibition by phenylboronic acids; a much reduced incorporation of phenylmethane[35S]sulphonyl fluoride into the enzyme in the presence of phenylboronic acid; the lack of interaction of histidine- or serine-modified enzyme with immobilized phenylboronic acid in the presence of glycerol (Ve/Vo = 2.7 and 2.3 respectively) when compared to the native enzyme (Ve/Vo = 5.25). Fatty acyl-lecithin-cholesterol acyltransferase, produced by incubation of the enzyme with a lecithin-apolipoprotein A-I proteoliposome substrate, was not retarded upon the sorbent column (Ve/Vo = 1.5). Modification of the enzyme's two free cysteine residues with 5,5'-dithiobis(2-nitrobenzoic acid) or potassium ferricyanide reduced (Ve/Vo = 3.5) but did not abolish retardation on the sorbent column, indicating that these modifications resulted in steric hinderance of the interaction of the boron atom with the lecithin-cholesterol acyltransferase serine hydroxyl group. These data suggest that the serine and histidine residues are proximal within the enzyme catalytic site and that both cysteine thiol groups are close to the serine hydroxyl group. The presence of significant amino-acid sequence homologies between lecithin-cholesterol acyltransferase, triacylglycerol lipases and the transacylases of fatty acid synthase is also reported.

Binding Sites↗
PubMed1994

Degree of fatty acyl chain unsaturation in biliary lecithin dictates cholesterol nucleation and crystal growth.

To clarify factors involved in the formation of cholesterol gallstones, we studied the relationship between the degree of fatty acyl chain unsaturation of biliary lecithin and bile metastability. We used supersaturated model bile solutions (molar taurocholate/lecithin/cholesterol ratio (73:19.5:7.5), total lipid concentration 9 g/dl) that contained equimolar egg yolk or soybean lecithins or a sn-1 palmitoyl, sn-2 linoleoyl phosphatidylcholine. Gel permeation chromatographic studies showed that the vesicular cholesterol distribution and dimension were inversely related to the degree of unsaturation of the lecithin species, estimated by reverse phase, high-performance liquid chromatography. Differential interference contrast microscopy and assay of cholesterol crystal growth showed that a higher degree of fatty acyl chain unsaturation of the lecithin species was associated with a faster nucleation time and rate of crystal growth. Our results suggest that vesicular lecithins containing more unsaturated fatty acyl chains bind less tightly to cholesterol than lecithins containing predominantly saturated fatty acids, and that the biliary lecithin species dictates, in part, the nucleation and growth of cholesterol crystals in bile.

Bile↗
PubMed1977

[Effect of dicarboxylic lecithins on liposomes].

We have investigated the effect of dicarboxylic lecithins on liposomes prepared from egg-lecithins and their incorporation into liposome preparation. In the presence of phospholipids, liposome cell permeability to glucose is five times higher than in controls. The incorporation of dicarboxylic lecithins into liposomes at a molar concentration of 50 molecules per cent reduces by 60% the amount of glucose trapped inside the liposomes. Measurements of ovolecithin-glutaryl-lecithin liposomes stability show that stable structures are formed at a molar concentration of 70 molecules per cent in the presence of cholesterol. On the contrary, the liposomes prepared in the absence of cholesterol are not stable at a molar concentration of 50 molecules per cent. Measurements of sedimentation of mixed dispersions of monocarboxylic lecithins and glutaryl-lecithins show that glutaryl-lecithins must be in the form of micelles to solubilize the phosphatidyl cholines.

Chemical Phenomena↗
PubMed2006

Highly sensitive spectrofluorimetric determination of trace amounts of lecithin using a norfloxacin-terbium probe.

BACKGROUND: Lecithin is found throughout biological systems. A new spectrofluorimetric method was developed for the determination of trace amounts of lecithin. METHODS: Optimum conditions for the determination of lecithin were investigated. RESULTS: Using norfloxacin (NF)-terbium ion (Tb3+) as a fluorescent probe, in a buffer solution at pH=6.80, lecithin reduced the fluorescence intensity of the NF-Tb3+ complex at lambda=545 nm; the reduced fluorescence intensity of the Tb3+ ion is proportional to the concentration of lecithin. The linear range and detection limit for the determination of lecithin were 1.08 x 10(-6)-3.02 x 10(-5) mol/l and 2.54 x 10(-7) mol/l. CONCLUSION: This method is simple, practical and relatively free of interference from coexisting substances, and can be successfully applied to assess lecithin in serum samples.

Cations↗
PubMed2005

Structural investigations on lipid nanoparticles containing high amounts of lecithin.

Solid lipid nanoparticles (SLN), an alternative colloidal drug delivery system to polymer nanoparticles, emulsions and liposomes, possess inherent low incorporation rates resulting from the crystalline structure of the solid lipid. To increase the drug loading capacity of SLN, matrix modification by incorporation of the amphiphilic lipid lecithin within the lipid matrices has been proposed as a promising alternative. The objective of this work is to investigate the effects of the lecithin on the microstructure of matrix modified SLN. In addition, these systems were checked for the existence of aggregates like mixed micelles, liposomes, etc., which could possibly be formed by lecithin leakage into the aqueous phase during the preparation process. For this purpose, laser diffraction, photon correlation spectroscopy (PCS), small angle X-ray scattering (SAXS), nuclear magnetic resonance (NMR) and transmission electron microscopy (TEM) were performed to investigate the structure, mobility, and molecular environment of the compounds. Lecithin incorporation within the lipid matrices resulted in a concentration dependent decrease in particle size up to a critical concentration of 30%. Lecithin incorporation up to 50% was investigated but caused no further particle size decrease. TEM revealed anisometrical and crystalline platelets of ellipsoidal to disc-like shape. Furthermore, SAXS and TEM showed no signs of lecithin and nonionic emulsifier derived aggregates in the aqueous phase. This points in agreement with NMR measurements to a strong attachment of both substances to the SLN surfaces. The proposed structure of the particles after melt emulsification consists of two different layers: a crystalline triglyceride-rich core is covered in dependence of the lecithin content either by a monomolecular or multimolecular lecithin/Solutol HS15 (SOL) layer.

Colloids↗
PubMed2000

Effects of lecithinized superoxide dismutase and a neutrophil elastase inhibitor (ONO-5046) on hyperoxic lung injury in rat.

Reactive oxygen and neutrophil metabolites have been implicated in the development of hyperoxic lung injury. We determined the protective effects of either a superoxide dismutase or neutrophil elastase inhibitor and the combination of both agents on the development of hyperoxic lung injury in rats. Two drugs (lecithinized superoxide dismutase and ONO-5046) were used in the present study. Lecithinized superoxide dismutase, a lecithin derivative bound to recombinant CuZn superoxide dismutase, has a higher affinity for cells such as polymorphonuclear leukocytes and endothelial cells than recombinant human superoxide dismutase. N-[2-[4-2,2-dimethylpropionyloxy) phenylsulfonylamino] benzoyl]¿ aminoacetic acid (ONO-5046), a specific neutrophil elastase inhibitor, which was developed as a low-molecular weight inhibitor, showed protective effects against various lung injuries. Rats were exposed to over 90% oxygen for 72 h, and bronchoalveolar lavage was performed to evaluate the permeability and neutrophil accumulation in the lungs. Rats were treated with lecithinized superoxide dismutase (30,000 U/day, intravenously n=7) or ONO-5046 (10 mg/kg, intramuscularly twice a day, n=7) or a combination of both drugs (n=7). Albumin concentration and neutrophil counts in bronchoalveolar lavage fluid were compared between animals with and without drug treatment. Either lecithinized superoxide dismutase or ONO-5046 treatment significantly decreased albumin concentration and neutrophil counts in bronchoalveolar lavage fluid compared to those in the animals of the hyperoxia-alone group (n=9). However, albumin leakage and neutrophil accumulation in the rat lung treated with combined agents were identical to that of either the lecithinized superoxide dismutase or ONO-5046 treatment. These findings suggest that lecithinized superoxide dismutase and ONO-5046 are useful drugs to protect against hyperoxic lung injury in rats. However, there were no additive effects by the combination in preventing hyperoxic lung injury.

Albumins↗