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At least 1,603 records · Page 89Linked to original sources
PubMed1983

(3-sn-Phosphatidyl)cholines (lecithins) in amniotic fluid.

Many currently used thin-layer chromatographic methods for phospholipid assay rely on charring the developed plate in the presence of cupric acetate. Saturated acyl phospholipids do not react. We find that substitution of cupric sulfate results in detection of both saturated and unsaturated phospholipids. By exploiting the difference with the two reagents, one can separately estimate the amounts of saturated phospholipid. The method described here is reproducible, and we illustrate its use in determinations of (3-sn-phosphatidyl)cholines (lecithins) in amniotic fluid from problem pregnancies.

Amniotic Fluid↗
PubMed1983

[Comparative study of the phospholipase activity of pathogenic and saprophytic Leptospira cultured on a serum-lecithin agar].

The phospholipase activity of leptospires cultivated on serum-lecithin agar has been studied. Two zones of changes in the medium have been found to appear around the colonies of saprophytic Leptospira strains: transparent (5.25 +/- 2.09 mm wide) and turbid (6.90 +/- +/- 1.46 mm wide), which is linked with the production of phospholipases A and C. Only a single clear zone is formed around the colonies of pathogenic strains due to the production of phospholipase A. At the same time virulent Leptospira strains show greater phospholipase activity (the zones are 6.0 +/- 1.2 mm wide) than avirulent strains (the zones are 1.6 +/- +/- 0.04 mm wide).

Agar↗
PubMed1983

Distribution of apolipoprotein A-IV between the lipoprotein and the lipoprotein-free fractions of rat plasma: possible role of lecithin:cholesterol acyltransferase.

Plasma samples were incubated under various conditions to study the effect of in vitro incubation on apolipoprotein A-IV distribution between the lipoprotein and lipoprotein-free fractions. When plasma was fractionated immediately after bleeding, apolipoprotein A-IV was present in equal concentrations in the lipoprotein and lipoprotein-free fractions. After a 4-hr, 37 degrees C incubation, greater than 90% of total plasma apolipoprotein A-IV was present in the lipoprotein fraction and the percentage of plasma cholesterol present as cholesteryl ester increased from 58% to 74%. When plasma was incubated for 4 hr at 37 degrees C in the presence of 1.5 mM 5,5-dithiobis(2-nitrobenzoic acid) (DTNB), greater than 90% of total plasma apoA-IV was present in the lipoprotein-free fraction, whereas plasma cholesteryl ester concentration did not change. Incubating heat-inactivated plasma for 4 hr also resulted in the redistribution of apolipoprotein A-IV from the lipoprotein fraction to the lipoprotein-free fraction, concurrent with no change in cholesterol esterification. When heat-inactivated plasma was incubated in the presence of a purified lecithin:cholesterol acyltransferase preparation, cholesterol esterification was restored and apolipoprotein A-IV was redistributed from the lipoprotein-free fraction to the lipoprotein fraction in such a manner that greater than 90% was present in the lipoprotein fraction. No changes in apolipoprotein A-I and apolipoprotein E distributions were found under any of the above conditions. Thus, the in vitro plasma incubations show that apolipoprotein A-IV can move bidirectionally between lipoprotein and lipoprotein-free fractions; the direction of this movement depends on the condition of the incubation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

[Lecithin therapy of hereditary ataxia].

Eight patients with Friedreich's ataxia and eight others with syndrome of spino-cerebellar degeneration received oral lecithin (21 g daily) for a six-month period. No relevant clinical change was note either during or soon after treatment. Statistical analysis was also irrelevant in the total number of patients. Similar results emerged when grouping the patients at the stage of the illness (stage II in contrast with stage III-IV). The outcome of therapeutical trials in literature is discussed in comparison with results.

Adolescent↗
PubMed1983

[Use of bromthymol blue for studying the thermotropic properties of the liposomes from egg lecithin].

The dependence of the turbidity changes at 615 nm monobilayers liposomes from egg yolk lecithin in the presence of bromothymol blue on temperature and storage conditions has been investigated. It is established that the thermotropic properties of liposomes change irregularly and depend on the storage conditions. Sharp release of the bound dye at temperature above 35-37 degrees C is associated with thermotropic change in liposomes and the detected effects, with the change of orientation of the phosphorylcholine group.

Animals↗
PubMedDate not supplied

[Structural transformations and aggregation stability of lecithin liposomes in cryoprotective media].

To study the structural transformations and aggregation stability in liposomes, a new approach is proposed whose efficiency is demonstrated during the analysis of light scattering by lecithin liposome sols doped with low-molecular cryoprotectors . This approach is used to determine absolute dimensions, relative values of weight concentration, masses of vesicules and their surface densities as well as their polydispersity characteristics. The anisotropic scattering data suggest that cryoprotectors eliminate small scale defects which are partially restored at low temperatures. Low-molecular cryoprotectors are found to produce some favourable changes in dimensions and distribution of liposomes and to increase their aggregation and structural stability.

Cryoprotective Agents↗
PubMed1981

[Effect of ethanol, acetazolamide, and cyclophosphamide on protein and lecithin concentrations in broncho-alveolar liquid film of mice].

An original approach to reveal in Mice, the impact of some xenobiotics and drugs on the alveolo-capillary barrier...(ethanol, acetazolamide, cyclophosphamide is described. Drugs are injected I.P. during five days in subacute dose size. Concentrations of lecithines and proteins are settled in bronchoalveolar lavage fluids from animals having or not undergone an important blood loss just before the lavage.

Acetazolamide↗
PubMed1982

Reversibility by L-carnitine of immunosuppression induced by an emulsion of soya bean oil, glycerol and egg lecithin.

Experimental and clinical data appear to indicate that Intralipid--an emulsion of soya bean oil, glycerol and egg lecithin--which is usually employed to improve caloric intake of parenteral nutrition regimens, may compromise human host defence mechanisms and therefore expose patients to an increased incidence of infectious diseases. Since from a biochemical point of view it has been suggested that a possible way whereby the somewhat poor reputation of Intralipid--attributable to the liver damage and the persistent lipaemia which attend its use--might be improved is to give supplementary carnitine which acts as a rate-limiting factor in the removal of the fat emulsion from blood, we hypothesized that the addition of carnitine to Intralipid could also result in a improvement of the immune responses both "in vitro" and "in vivo". Our results lend some support to the hypothesis in favour of a metabolic basis for some of the immunosuppressive properties of Intralipid and justify the inclusion of L-carnitine in parenteral nutrition regimens which, by abrogating some co-factor limitation, improves the immune responses of the host.

Carnitine↗
PubMed1981

Demonstration of an interaction of the radioprotector cysteamine with lecithin.

Cysteamine, a radioprotector belonging to the aminothiol class, interacts with nucleus DNA of mammalian or human cells to reduce the lethal effect of ionizing radiation. The transfer of this drug through cellular membranes has been studied, using as a model system an aqueous dispersion of lipid and cysteamine. The interaction of synthetic lecithin dipalmitoylphosphatidylcholine (DPPC) smectic mesophases with cysteamine was investigated by means of spectrophotometric and dielectric measurements. The thermal transitions of DPPC studied by spectrophotometry and dielectric Arrhenius diagrams showed that cysteamine deletes the pretransition of the lipid phase and does not modify the principal transition. This indicates a direct interaction between the lipid polar head with cysteamine; the aliphatic chains are not affected. Conductivity measurements confirmed these results and demonstrated an electrostatic interaction between the anionic phosphate site of the polar head and the cysteamine cation.

Chemical Phenomena↗
PubMedDate not supplied

[Pharmacological influences on fetal lung maturity, part V: Influencing the pulmonary DPL (dipalmitoyl lecithin) level with L-thyroxin (T4)].

Dipalmitoyl lecithin (DPL = DPPC, dipalmitoyl phosphatidyl choline) is both quantitatively and functionally the most important constituent of the surfactant complex. The effect of thyroxin (T4) on fetal lung maturity was investigated by means of selective DPL determination. Following administration of thyroxin to the mother animal an increase in the DPPC content was demonstrated in rat fetuses. This increase was greater than that of the total phospholipids. This effect of thyroxin could be due to the following causes: 1, Earlier and accelerated differentiation of lung cells: more Type II cells are formed earlier and these synthesize DPPC more effectively than other lung cells (approx. 40-50% of the phosphocoline in Type II cells in DPPC). 2. Stimulation of the deacylation-reacylation cycle. 3. A combination of these mechanisms.

Amniotic Fluid↗
PubMed1980

[Esterification of cholesterol in patients with renal transplants. Determination of lecithin:cholesterol-acyl-transferase (LCAT) activity].

In man, cholesterol esterification is controlled by lecithin:cholesterol-acyl-transferase (LCAT), which is a key-role enzyme of lipid metabolism. Though LCAT is synthesized by the hepatocytes, its activity seems to be linked to the kidney: in fact, LCAT activity is lowered in uremic and anephric subjects, and probably also in long-term haemodialysis patients. On the contrary, in successfull renal allografts we found fully restored LCAT activity. But physiopathological mechanisms underlying relationships between LCAT and kidney are still unclarified.

Cholesterol↗
PubMed1982

Lecithin:sphingomyelin ratio in pregnancies complicated by insulin-dependent diabetes mellitus.

One hundred forty-one samples of amniotic fluid in 105 pregnancies from 95 insulin-dependent diabetics were analyzed for the lecithin:sphingomyelin (L:S) ratio. Fetal pulmonary maturity seemed to progress at a normal rate. The mean L:S ratio was not significantly different in diabetic and nondiabetic patients at various stages of gestation. Only 3 cases of respiratory distress syndrome (RDS) were observed in 77 infants with an L:S ratio of 2.0 or more delivered of diabetic mothers within 72 hours of amniocentesis. This 3.9% incidence of RDS in infants of diabetic mothers with L:S ratios of more than 2.0 was not significantly higher than the 1.5% incidence in the nondiabetic mothers. It is concluded that by using the method of Gluck, an L:S ratio of 2.0 or greater at 36 weeks' gestation or later is a reliable indicator of fetal lung maturity in insulin-dependent diabetic pregnancies, and abdominal delivery after 36 weeks' gestation does not increase the risk of RDS in a diabetic pregnancy with an L:S ratio at 2.0 or more.

Amniocentesis↗
PubMed1982

Liquid-chromatographic estimation of saturated phospholipid palmitate in amniotic fluid compared with a thin-layer chromatographic method for acetone-precipitated lecithin.

The "high-performance" liquid-chromatographic method we report for measuring palmitate derived from saturated phospholipids in amniotic fluid is sensitive and precise and possesses a wide dynamic range. Palmitate from nonsurfactant sources is largely excluded. The procedure involves oxidation of the chloroform/methanol-extracted lipids with osmium tetroxide, precipitation of the resulting phosphatides with cold acetone, mild alkaline hydrolysis, derivatization of the liberated fatty acids to phenacyl esters, and reversed-phase chromatography. The method is no less convenient or more time-consuming than measurement of the lecithin/sphingomyelin ratio by thin-layer chromatography. The clinical usefulness of the procedure is indicated by results of a correlative study of 26 amniotic fluids evaluated by "lung profile" tests in a second laboratory. A value for dipalmitoyl lecithin of 13 mg/L or greater indicates fetal lung maturity.

Acetone↗
PubMed1982

The relative fatty acid composition of serum lecithin in one woman with essential hypertension superimposed by severe preeclampsia.

A hospitalized woman with essential hypertension complicated by severe preeclampsia was serially studied in the end of her pregnancy and in the puerperal period. The relative composition of serum lecithin fatty acids was analyzed by gas-liquid chromatography. In the present case, the main finding during pregnancy was a dramatic decrease of the linoleic acid parallel to a vast increase of nonessential fatty acids. Of these fatty acids, 20:3 of the oleic acid series was found in an extremely high quantity which may suggest a compensatory mechanism to reduced levels of essential polyenoic fatty acids. It was suggested that the linoleic acid decrement was mainly associated with the disease. These changes were found to be enhancements of differences earlier found between preeclamptic and normal pregnant women.

Fatty Acids↗
PubMedDate not supplied

[Effect of monochromatic light on oxygen transport across the multibilayer lecithin film pigmented wih carotene].

The permeability of beta-carotene-pigmented lecithin multibilayer was studied under the effect of monochromatic illumination for O2 in media with various ionic composition. It is shown that illumination of film within the 400 to 500 nm wavelengths causes a decrease in the permeability of the multibilayer for O2. The effect of light depends on the cation type. Hydration of the multilbilayer within the NaCl solution recovers the permeability of the system after switching of the light. In CaC12 solutions the light reaction is more pronounced but after the light switching off there is no the reversible recovery of the permeability for O2.

Biological Transport↗
PubMed1978

The site of amniocentesis and the lecithin-sphingomyelin ratio.

Simultaneous sampling of amniotic fluid from two sites within the amniotic cavity proximal and distal to the fetal mouth was performed. The lecithin-sphingomyelin (L/S) ratio of amniotic fluid obtained close to the fetal mouth was usually higher than that of amniotic fluid obtained from a site distal to the fetal mouth (20 of 26 cases). Differences of up to 0.7 in the two L/S ratios were measured. This suggested that pooling of amniotic fluid phospholipids occurred and in cases of borderline pulmonary maturity the site of amniocentesis may have influenced the predictive value of the L/S ratio.

Adult↗
PubMed1981

Severity of respiratory distress syndrome with low lecithin: sphingomyelin ratio.

The frequency and severity of respiratory distress syndrome (RDS) were evaluated in 69 infants whose amniotic fluid lecithin: sphingomyelin (L:S) ratio was less than 2. Amniotic fluid was obtained at the time of either nonelective or elective cesarean section in 58 cases. An additional 11 patients were delivered within 48 hours after amniocentesis. Gestational ages ranged from 27 to 41 weeks. Few women had been in labor, none had ruptured membranes for more than 12 hours, and all but 3 were delivered by cesarean section. A variety of pregnancy complications were represented. All 14 infants with an L:S ratio less than 0.5 developed RDS, and 10 died. Of 19 infants with an L:S ratio of 0.5 to 0.99, 8 developed RDS; 3 of the 8 died and another 3 required ventilatory support. Of 36 infants whose L:S ratio exceeded 1.0, only 1 developed RDS. No infant who had an L:S ratio greater than 0.8 died of RDS, and RDS was absent in infants with L:S ratio as low as 0.6. These findings could not be attributed to intraassay or interassay variability or to laboratory methodology. The importance of individual laboratory evaluation of L:S values in relation to respiratory outcome is emphasized.

Amniotic Fluid↗
PubMed1981

A study of the interaction of lecithin: cholesterol acyltransferase with subfractions of high density lipoproteins.

High density lipoproteins (HDL) were isolated by a chromatographic procedure and subsequently fractionated on a DEAE cellulose (DE-52) column. Four fractions were separated and analyzed for lipid and protein composition and molecular weight. During ion exchange chromatography, one of the four fractions consistently coincided with lecithin:cholesterol acyltransferase (LCAT) activity. When the HDL fractions were incubated with highly purified LCAT preparations, the LCAT activity showed a dependence on unesterified cholesterol concentrations. The HDL subfraction eluting at the highest ionic strength was found to be the best substrate for LCAT. This subfraction exhibited apoprotein and lipid composition similar to HDL3 and contained 31% of the total apoprotein D present in all the subfractions. A positive correlation was found between LCAT activity and the cholesteryl ester/unesterified cholesterol ratio, and a negative correlation was found between LCAT substrate potential and apparent molecular weight of the HDL subfractions when these subfractions were incubated with LCAT. No correlation was apparent between LCAT activity, and the phospholipid/unesterified cholesterol ratio or with the apoA-I/apoA-II ratio.U

Cholesterol↗