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At least 721 records · Page 40Linked to original sources
PubMed1987

Lecithin: absence of neurophysiologic effect in Alzheimer's disease by EEG topography.

Ten patients with Alzheimer's disease participated in a 26-week double-blind trial of lecithin. EEG data were recorded at baseline, after administration of the placebo, and after administration of the drug. Topographic maps of EEG spectra were compared when patients were on and off drugs. A direct comparison of drug and nondrug data was not significant. A second approach, comparing differences between drug and nondrug with differences between the two nondrug conditions, also produced no evidence of a drug treatment effect. The data confirm other reports that lecithin has no effect upon spectrally analyzed EEG activity in Alzheimer's disease.

Aged↗
PubMed1989

Enhancing effect of medium-chain triglycerides on intestinal absorption of d-alpha-tocopherol acetate from lecithin-dispersed preparations in the rat.

The effect of formulations of lecithin-dispersed preparation on the absorption of d-alpha-tocopherol acetate (VEA) from the small intestine was investigated in rats. When lecithin-dispersed preparations containing VEA or polysorbate 80 (PS-80)-solubilized solution of VEA were intraduodenally administered, VEA was hydrolyzed to d-alpha-tocopherol (VE) and was not detected in the plasma nor in the thoracic lymph. The maximum plasma concentration (Cmax) of VE after the intraduodenal administration of a preparation consisting of VEA, soybean phosphatidylcholine (PC) and medium-chain triglycerides (MCTG) (VEA/PC/MCTG, 5/16/1 by weight) was highest among the VEA preparations, and PS-80-solubilized solution gave the lowest Cmax. AUC of VE up to 24 h was also increased by the addition of MCTG to VEA/PC preparation. In the thoracic duct-fistula rat, the transport of VE into the thoracic lymph was increased by the administration of the VEA/PC/MCTG preparation significantly more than the VEA/PC preparation; the cumulative amounts of VE recovered in the thoracic lymph up to 24 h were 23.2 +/- 0.5% and 10.9 +/- 1.5% of dose, respectively. The plasma concentration of VE was not increased in the thoracic duct-fistula rat even after the intraduodenal administration of VEA preparations, suggesting that VE is not transported directly to the systemic circulation, but by way of the lymphatic route. The lymphatic transport of VE following the intraduodenal administration of VEA/PC/MCTG preparation was markedly diminished by the simultaneous administration of Pluronic L-81 emulsion, an inhibitor of chylomicron formation. It is suggested that the chylomicron is essential to the lymphatic transport of VE from VEA preparations.

Animals↗
PubMed1999

Preparation of lecithin microcapsules by a dilution method using the Wurster process for intraarterial administration in gadolinium neutron capture therapy.

Lecithin microcapsules containing gadolinium (Gd) were designed and prepared as a dosage form for intraarterial administration to accumulate Gd in tumors in neutron capture therapy. The microcapsules were composed of 1) a lactose core, 2) a layer of distearylamide of gadopentetic acid (Gd-DTPA-SAm) and polyvinylpyrrolidone (PVP) with or without soybean lecithin (SL) and 3) a membrane containing SL, cholesterol, stearic acid and PVP at three different compositions. A dilution method using the Wurster process was developed for small-scale preparation. In spite of using only 2 g of Gd-DTPA-SAm each, three types of microcapsules were obtained with a content of 24.9% as Gd-DTPA-SAm (3.66% as Gd) even at 150% coating level. The swelling type of microcapsules (MC-D1) did not release Gd at all for the entire 120 min of the experiment in a 0.9% saline solution. On the other hand, the rapid-erosion type (MC-D2) and the vesicle-dispersing type (MC-D3) released Gd with a lag time. The percent released depended on the coating level and the SL content in the Gd-fixing layer. A large number of droplet-like particles spouted out, and/or tubular vesicles formed with MC-D2 and MC-D3 in the saline solution. These phenomena implied that the water-insoluble Gd-DTPA-SAm would be entrapped in these particles/vesicles. When MC-D2 and MC-D3 were administered to normal rats via the hepatic artery, a Gd-accumulation as high as 70 and 71% of the injected dose was detected in the whole liver 2 h after administration. In addition, biochemical and histological evaluation of the liver after administration indicated that embolization of the microcapsules actually occurred in the blood vessels, and that necrosis induced by ischemia was not serious. These results suggested that administration of these microcapsules might be multiply repeated in order to accumulate the required amount of Gd in tumors.

Animals↗
PubMed1997

Effect of lecithinized-superoxide dismutase on the rat colitis model induced by dextran sulfate sodium.

Lecithinized-superoxide dismutase (PC-SOD), which is synthesized with a lecithin derivative bound covalently to recombinant human Cu,Zn-SOD, has a longer half-life in blood and higher cell affinity than unmodified SOD. The effects of PC-SOD were evaluated using the rat ulcerative colitis model induced by 3% dextran sulfate sodium. Intravenous injection of rats with 0.5 or 1 mg/kg of PC-SOD suppressed the progression of bloody stools, the formation of erosion, and the infiltration of the colon with inflammatory cells. Furthermore, it also reduced the increase of leukocytes in blood. Thus, PC-SOD may have therapeutic potential in the treatment of ulcerative colitis.

Animals↗
PubMed1997

Effect of lecithinized-superoxide dismutase on the interstitial pneumonia model induced by bleomycin in mice.

Superoxide anion (O2-) acts as an exacerbation factor in interstitial pneumonia. Lecithinized-superoxide dismutase (PC-SOD), which is synthesized with a lecithin derivative bound covalently to recombinant human Cu,Zn-SOD, has a longer half-life in plasma and higher affinity to cell membranes than unmodified SOD. The effect of PC-SOD was evaluated using the bleomycin-induced interstitial pneumonia mouse model. Treatment with PC-SOD at 10 mg/kg significantly reduced the hydroxyproline content and fibrosis score. Namely, PC-SOD suppressed the progression of pulmonary fibrosis on the bleomycin-induced interstitial pneumonia mouse model. PC-SOD may be a potential drug for interstitial pneumonia therapy.

Animals↗
PubMed1975

The destruction of type 2 pneumocytes by airborne influenza PR8-A virus; its effect on surfactant and lecithin content of the pneumonic lesions of mice.

Influenzal pneumonia has been studied in mice subjected to sublethal doses of airborne PR8-A influenza virus. Electron microscopy revealed that the virus propagated in and at the same time destroyed the ciliated and nonciliated bronchial cells and the types 1 and 2 alveolar pneumocytes. The regenerating bronchial membranes were metaplastic and grew peripherally into the surrounding alveolar ducts and alveoli to form epithelial nodules which caused obstruction and collapse of the involved lobes. The development of the lung lesions was correlated with phospholipid (lecithin) levels in consolidated and unconsolidated infected and normal lungs. As the lungs became more and more consolidated, there was a corresponding and significant decrease in the amount of phospholipid (dipalmitoyl lecithin) compared to the amount of normal or unconsolidated infected tissue. The destruction of the type 2 pneumocytes by the influenza virus and their failure to regenerate is considered to be the reason for the low phospholipid levels in the involved lobes, and thus an important cause of post-influenzal collapse in mice. The above adds additional evidence to the view that the type 2 pneumocytes are a major source of surfactant in mammalian lungs.

Aerosols↗
PubMed1993

Decreased activation of lecithin:cholesterol acyltransferase by glycated apolipoprotein A-I.

Non-enzymatic glycation of plasma proteins may contribute to the excess risk of developing atherosclerosis in patients with diabetes mellitus. Glycated apolipoprotein A-I isolated from diabetic subjects was tested in vitro for its ability to activate lecithin:cholesterol acyltransferase, the principal cholesterol-esterifying enzyme in plasma. Activation by glycated apolipoprotein A-I was significantly lower at all concentrations than the activation by normal apolipoprotein A-I. Linear regression analysis of the kinetic data shows that the ratio app Vmax/app Km was significantly lower (p < 0.01) for glycated apolipoprotein A-I (0.29 nmol.l/h.mumol) than for normal apolipoprotein A-I (0.78 nmol.l/h.mumol). Because lecithin:cholesterol acyltransferase provides a driving force in reverse cholesterol transport by esterifying the cellular cholesterol removed by HDL, it is tempting to postulate that this abnormal activation may be associated with a reduction in reverse cholesterol transport and associated with the accelerated development of atherosclerosis in diabetic patients.

Apolipoproteins A↗
PubMed1976

A comparative study between the values of lecithin, sphingomyelin, lysolecithin, the L/S index, and the Clements test in amniotic fluid.

The relationship between the concentration of several phospholipids in amniotic fluid and the ocurrence of neonatal RDS was established some years ago. However the methods used for the determination of those substances are sophisticated and time consuming. They require specalized equipment and take at least 2 or 3 hours. CLEMENTS described a semiquantitative method which overcomes these disadvantages. The present study compared the concentration of lecithin, shingomyelin, lysolecithin and the L/S ratio against the results obtained when processing the same samples with the CLEMENTS Test. the results are expressed in mg/100 ml. for the different phospholipids and the test was evaluated as positive, intermediate or negative. a statistically significant correlation has been found between the values of lecithin, lysolecithin and L/S ratio and the results of the CLEMENTS Test, respectively. No correlation could be found with sphingomyelin (Figs. 1-4). It is concluded that the CLEMENTS Test can be a useful tool as a screening test available to any obstetrical centre.

Amniotic Fluid↗
PubMedDate not supplied

The specificity of ionophore A23187 in cation transport across lipid membranes. Studies with lecithin vesicles.

Lecithin vesicles containing different cations were prepared by sonication and characterized. When the concentration of the divalent cations in the buffer was increased from 1 mM to about 100 mM the cation-concentration inside of the vesicles did not increase proportional to the outside concentration, but showed a saturation behaviour. The efflux of various cations mediated by ionophore A23187 was measured and relative transport-rates were determined. The following sequence was obtained: Zn2+ > Ca2+ > Mg2+ > Sr2+ > Ba2+ approximately Li+ > Na+. The efflux of Ca2+ increased proportional to the square of the A23187-concentration. To lecithin-vesicles containing ethylenediamine tetraacetate (EDTA) inside different cations were added on the outside. In the presence of A23187 divalent cations are transported into the vesicles and bound there by EDTA. During the influx of Me2+-ions into vesicles a H+-efflux was observed. The resulting pH-decrease was measured. The rate of the pH-change depended on the Me2+-ion used. The sequence was: Cd2+ > Zn2+ > Ca2+ > Mn2+ > MG2+ > Sr2+, Ba2+.

Anti-Bacterial Agents↗
PubMedDate not supplied

Kinetics of proton-hydroxyl transport across lecithin vesicle membranes as measured with a lipoid pH-indicator.

When unilamellar vesicles are prepared in the presence of 3-Palmitoyl-7-ocy-coumarin abbreviation 3P-UBF) this lipoid pH-Indicator is anchored by its fatty acid chain to the membrane and can be used to measure pH-changes at the outer and inner membrane surface (ranging from pH to pH 9.5). By rapidly changing the pH of the outer aqueous phase a pH-gradient is set up across the vesicle membrane. The rate of the subsequent H+ or OH- influx into the vesicles can be measured as a change of the 3P-UBF absorbance at 424 nm. This was done with a stopped-flow -spectrophotometer at temperatures between 10 degree C and 50 degree C. Suspensions of vesicles prepared from egg-lecithin or L-dipalmitoyl-lecithin were investigated in buffered salt solutions. The influence of Na+, K+, Cl-, SO2-(4) and valinomycin on the rate of absorbance changes was studied at different temperatures. It was found that the rate of the pH-equilibration between the aqueous phase outside and inside the vesicles depends on the direction of the pH-gradient. This new result together with a high H+/OH- permeability of vesicle membranes found in recent studies from other laboratories and confirmed by this investigation is interpreted to indicated a higher permeability of the vesicle membrance to OH--ions compared to H+-ions. (Calculated values are: POH = 1.4 x 10(-4) cm/s at pH9 and PH = 8.3 x 10 (-7) cm/s at pH 5 and 20 degree C.) All data described in the literature in detail agree with this suggestion but a pH-dependence of POH and PH cannot be excluded.

Hydrogen-Ion Concentration↗
PubMed1996

Behavior of horses is affected by soy lecithin and corn oil in the diet.

To test the hypothesis that dietary fats may improve tractability of horses, the effects of four total mixed diets on behavior were compared. The control diet (CON) contained chopped hay, corn, oats, beet pulp, molasses and a mineral mix; the three test diets contained an additional 10% (by weight) corn oil (CO), soy lecithin-corn oil (SL-CO), or soy lecithin-soy oil (SL-SO). Eight horses were fed each diet in random order for four 3-wk periods. Behavior was observed during the last week of each feeding period. Spontaneous activity was evaluated using a pedometer and was less in horses fed SL-CO than in controls (P = .022). Reactivity was evaluated as responses to pressure, loud noise, and sudden visual stimuli. Compared with results for control horses, reactivity was less in horses fed SL-CO during the visual stimulus test (P = .036), in horses fed CO in the noise test, the pressure test, and the visual stimulus test (P = .093, .108, and .116 respectively), and in horses fed SL-SO during the visual stimulus test (P = .108). These results provide the first quantitative evidence that dietary fats reduce the activity and reactivity of horses.

Animals↗
PubMed1991

Inhibition of lipid peroxidation of lecithin liposomes kept in a pH-stat system near neutral pH.

During 5 days of autoxidation of egg lecithin liposomes in nonbuffered saline pH dropped from an initial value of 7.4 to 4.5. A linear relationship between oxidation index and pH was obtained. Lipid peroxidation, monitored as conjugated diene and TBA-reactive products, was inhibited significantly by keeping the samples under pH-controlled conditions (7.4 +/- 0.5), compared to controls. Obtained results indicate that the buffering capacity of Tris and Hepes buffers may play a role in their recently reported (D. Fiorentini et al. (1989) Free Radical Res. Commun., 6, 243) inhibitory action against lipid peroxidation of lecithin liposomes.

Buffers↗
PubMed1988

Limitation of complement activation by perfluorocarbon emulsions: superiority of lecithin-emulsified preparations.

A considerable body of evidence suggests that complement and granulocyte activation may be important in the occasional adverse reactions which occur on the administration of perfluorocarbon emulsions to patients. In an attempt to develop an emulsion which was less prone to activate complement than was the first product clinically tested, we devised an in-vitro protocol for the testing of an emulsion's ability to activate complement: emulsions were serially diluted, and were incubated with minimally-heparinized plasmas from each of several donors; the generation of C3a was assessed by commercial immunoassay. In such a system, F-Adamantane emulsions prepared with highly-purified lecithin as the emulsifier were consistently less complement-activating than comparable emulsions prepared with Pluronic F-68 as the emulsifier. Emulsification technique seemed unimportant, and HPLC fractionation of the Pluronics identified no innocuous subfraction. Application of these findings to an animal model is underway, to see if the superiority of lecithin-based emulsions is also evident in vivo.

Adamantane↗
PubMed1976

[Course observation after intra-amniotic administration of lecithin in premature cesarean section].

A report of a 36 year old patient is given who was hospitalized because of an erythroblastosis. An indicated sectio caesarea resulted in an intraamnial application of lecithine for preventing a respiratory distress syndrome. It can be concluded by the measured lecithin-concentration that a high phospholipid-level in the amniotic fluid leads to an increased resorption by the fetus. Postpartal investigations showed a completely normal lung function in the newborne.

Amnion↗
PubMed1976

Action of heparin on lecithin:cholesterol acyltransferase activity in normal subjects.

The triglyceride decrease and free fatty acid increase by lipoproteinlipase post-heparin effect does not modify the Lecithin:Cholesterol Acyltransferase activity in vitro, using homologous substrate, in normal subjects. These findings agree with the unmodified proportion of esterified cholesterol and relative proportion of phospholipids on thin layer chromatographic fractioning after heparin. The conclusion is reached that heparin has no action on Lecithin:Cholesterol Acyltransferase activity in normal subjects.

Acyltransferases↗
PubMedDate not supplied

Investigation of diazepam lipospheres based on Witepsol and lecithin intended for oral or rectal delivery.

Diazepam was incorporated in lipospheres prepared by high pressure homogenization of melted Witepsol (10%) dispersed in aqueous lecithin (2.4%). Diazepam content was 0.4% and more than 98% of the dose was found to be encapsulated in the lipospheres. Although the initial mean particle size was 0.3 micron, the liposhperes agglomerated during storage and this phenomenon was not eliminated by increasing lecithin concentration to 4% or incorporation of oleic acid (0.1%) and co-surfactants, polysorbate 80 (0.5%) or poloxamer (up to 6%). The formulation was not able to mask effectively bitter taste of diazepam, even when lipids of higher melting temperature, namely glyceryl tripalmitate or stearic acid, were introduced.

Administration, Oral↗
PubMed1975

Lecithin---sphingomyelin ratio in amniotic fluid, as assessed by a modified thin-layer chromatographic method in which a commercial pre-coated plate is used.

Commercially available pre-coated thin-layer chromatographic plates consisting of silica gel supported on aluminum sheets were used to determine the lecithin-sphingomyelin ration in samples of amniotic fluid. These lipids were separated in chloroform-methanol-water (65:25:4 by vol) solvent system (lecithin Rf = 0.33; sphingomyelin, Rf = 0.25), and the spots were made visible in 5-15 min by heating to 180 degrees C after spraying with a solution of copper acetate (30 g/liter) in aqueous phosphoric acid (80 g/liter). The lipids were measured densitometrically after "peeling off" the adsorbent containing the spots by using a transparent cellulose ("Scotch brand") adhesive tape. Virtues of the original Gluck procedure are retained without need to heat the plates to 280 degrees C after spraying with corrosive aqueous sulfuric acid (698 g/liter) to make the lipids visible. Results for synthetic mixtures in concentrations within the physiological range and with a ratio of 0.5 to 3.0 showed an accuracy of 99% pluss or minus 7% (SD.).

Amniotic Fluid↗
PubMed2001

Genomic organization and mutation analysis of the gene encoding lecithin retinol acyltransferase in human retinal pigment epithelium.

PURPOSE: To determine the structure of the human lecithin retinol acyltransferase (LRAT) gene, map its chromosomal localization, and screen for mutations in humans with various hereditary retinal degenerations. METHODS: Using DNA probes specific for LRAT, a bacterial artificial chromosome (BAC) clone containing the LRAT gene was isolated, subcloned into DNA fragments and relevant subclones characterized by sequencing. Exon-intron junctions were determined by comparison with the cDNA sequence previously published. Southern blot analysis was performed on human genomic DNA samples digested with several restriction enzymes. Fluorescence in situ hybridization (FISH) analysis of normal metaphase chromosomes derived from phytohemagglutinin (PHA) stimulated peripheral blood lymphocytes and radiation hybrid mapping were used for localization of the LRAT gene. Single-strand conformation polymorphism analysis (SSCP) was used to screen for potential mutations in patients with age-related macular degeneration, Leber congenital amaurosis, retinitis pigmentosa, and cone-rod dystrophy. RESULTS: The human LRAT gene is organized into three exons of 219, 541, and 2058 bp and two introns of 103 and 4117 bp. Southern blot analysis of digested genomic DNA revealed a single band, suggesting a single copy of the LRAT gene. The human LRAT gene was localized to chromosome 4q31.2, a locus having no previous association with human eye disease. Additionally, the bovine LRAT homologue sequence was deduced and a general LRAT protein topology is suggested. No polymorphisms that segregated with retinal disease phenotypes were identified in 374 unrelated probands. CONCLUSIONS: The organization of the LRAT gene, based on cDNA clones derived from the retinal pigment epithelium (RPE) has been determined. Its structure is less complex than other acyltransferases such as lecithin cholesterol acyltransferase (LCAT) and acyl CoA acyltransferase (ACAT). The absence of polymorphisms in the probands examined suggests a very low mutation level in the LRAT gene from the diseases analyzed.

Acyltransferases↗