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PubMed1998

Expression of mannose-ligand receptors on human spermatozoa: effect of lecithin and association with sperm binding to the zona pellucida.

OBJECTIVE: To evaluate the change in the expression of mannose-ligand receptors and sperm binding capacity after the incubation of sperm cells with lecithin liposomes. DESIGN: A randomized, blinded-controlled experiment. SETTING: Andrology laboratory at the Lis Maternity Hospital. PATIENT(S): Fifteen fertile sperm donors and 10 subfertile men. INTERVENTION(S): Incubation of sperm samples with either control medium or 1 mg/mL of liposomal lecithin for 2 hours. MAIN OUTCOME MEASURE(S): Expression of mannose-ligand receptors as evaluated by mannosylated bovine serum albumin-fluorescein isothiocyanate and sperm binding to the zona pellucida as evaluated by the hemizona assay. RESULT(S): The mean +/- SE percentages of spermatozoa with patterns I, II, and III were 86% +/- 4.8%, 11% +/- 3.4%, and 3% +/- 1.6%, respectively, after treatment with control medium and 71% +/- 5.7%, 22% +/- 3.5%, and 7% +/- 2.5%, respectively, after treatment with lecithin. The same effect of lecithin was observed in the 10 sperm samples from subfertile men. The mean +/- SE numbers of sperm that bound to hemizonae after treatment with control medium or lecithin were 116 +/- 32.4 and 176 +/- 29.6, respectively. Statistically significant correlations were observed between the shift in patterns II and III and the enhancement of sperm binding after lecithin treatment (r = 0.44 and 0.6, respectively). CONCLUSION(S): Lecithin shifts the expression of mannose-ligand receptors to the capacitated and acrosoine-reacted patterns and enhances the binding capacity of the sperm cells.

Adult↗
PubMed2003

Effects of dietary soybean lecithin on plasma lipid transport and hepatic cholesterol metabolism in rats.

Dietary lecithin can stimulate bile formation and biliary lipid secretion, particularly cholesterol output in bile. Studies also suggested that the lecithin-rich diet might modify hepatic cholesterol homeostasis and lipoprotein metabolism. Therefore, we examined hepatic activities of 3-hydroxy-3 methylglutaryl coenzyme A reductase "HMG -CoA reductase", cholesterol 7 alpha-hydroxylase and acyl-CoA: cholesterol acyltransferase "ACAT" as well as plasma lipids and lipoprotein composition in rats fed diets enriched with 20% of soybean lecithin during 14 days. We also evaluated the content of hepatic canalicular membrane proteins involved in lipid transport to the bile (all P-glycoproteins as detected by the C 219 antibody and the sister of P-glycoprotein "spgp" or bile acid export pump) by Western blotting. As predicted, lecithin diet modified hepatic cholesterol homeostasis. The activity of hepatic HMG-CoA reductase and cholesterol 7 alpha-hydroxylase was enhanced by 30 and 12% respectively, while microsomal ACAT activity showed a dramatic decrease of 75%. As previously reported from ACAT inhibition, the plasma level and size of very low-density lipoprotein (VLDL) were significantly decreased and bile acid pool size and biliary lipid output were significantly increased. The canalicular membrane content of lipid transporters was not significantly affected by dietary lecithin. The current data on inhibition of ACAT activity and related metabolic effects by lecithin mimic the previously reported effects following drug-induced inhibition of ACAT activity, suggesting potential beneficial effects of dietary lecithin supplementation in vascular disease.

Acyl Coenzyme A↗
PubMed1985

Methyl branching in short-chain lecithins: are both chains important for effective phospholipase A2 activity?

Several seven-carbon fatty acyl lecithins with varied acyl chain branching have been synthesized and characterized as potential phospholipase A2 substrates. Micellar bis(4,4-dimethylpentanoyl) phosphatidylcholine, bis(5-methylhexanoyl)phosphatidylcholine, bis(3-methylhexanoyl)phosphatidylcholine, and bis(2-methylhexanoyl)phosphatidylcholine are poor substrates for phospholipase A2 (Naja naja naja). These branched lecithins also inhibit the hydrolysis of diheptanoylphosphatidylcholine by the enzyme with Ki values comparable to or smaller than the apparent Km of the linear compound. The terminally branched lecithins are excellent substrates for another surface-active hydrolytic enzyme, phospholipase C from Bacillus cereus. When only one acyl chain bears a methyl group, the hybrid lecithins 1-heptanoyl-2-(2-methylhexanoyl)phosphatidylcholine and 1-(3-methylhexanoyl)-2-heptanoylphosphatidylcholine are substrates comparable to diheptanoylphosphatidylcholine. Analysis of micellar structure and dynamics by 1H and 13C NMR spectroscopy, quasi-elastic light scattering, and comparison of critical micellar concentrations indicates little significant difference in the conformation and dynamics of these seven-carbon fatty acyl lecithin micelles, even when the methyl groups are adjacent to the carbonyls. Phospholipase A2 UV difference spectra induced by phospholipid binding imply different enzyme conformations or aggregation states caused by linear-chain and asymmetric-chain lipids compared to bis(methylhexanoyl)phosphatidylcholines. The differences in hydrolytic activity of phospholipase A2 against the branched-chain micellar lecithins can then be attributed to an enzyme-lipid interaction at the active site. The species with both fatty acyl chains branched bind to phospholipase A2 but are not turned over rapidly. Since poor enzymatic activity only occurs for lecithins with both chains methylated, the interaction of both chains with the enzyme must be important for catalytic efficiency.

Kinetics↗
PubMed1997

Structural mechanisms of bile salt-induced growth of small unilamellar cholesterol-lecithin vesicles.

The liver secretes cholesterol and lecithin in the form of mixed vesicles during the formation of bile. When exposed to bile salts, these metastable vesicles undergo various structural rearrangements. We have examined the effects of three different bile salts, taurocholate (TC), tauroursodeoxycholate (TUDC), and taurodeoxycholate (TDC), on the stability of sonicated lecithin vesicles containing various amounts of cholesterol. Vesicle growth was probed by turbidity measurements, quasi-elastic light scattering, and a resonance energy transfer lipid-mixing assay. Leakage of internal contents was monitored by encapsulation of fluorescence probes in vesicles. At low bile salt-to-lecithin ratios (TC/L or TUDC/L < 1), pure lecithin vesicles do not grow, but exhibit slow intervesicular mixing of lipids as well as gradual leakage. At high BS/L (TC/L or TUDC/L > 5), pure lecithin vesicles are solubilized into mixed micelles with a concomitant decrease in the overall particle size. In this regime, extensive leakage and lipid mixing occur instantaneously after exposure to bile salt. At intermediate BS/L (1 < TC/L or TUDC/L < 5), vesicles grow with time, and the rates of both leakage and lipid mixing are rapid. The data suggest that vesicles grow by the transfer of lecithin and cholesterol via diffusion in the aqueous medium. The addition of cholesterol to lecithin vesicles reduces leakage dramatically and increases the amount of BS required for complete solubilization of vesicles. The more hydrophobic TDC induces vesicle growth at a lower BS/L than does TC or TUDC. These results demonstrate the physiologic forms of lipid microstructures during bile formation and explain how the hydrophilic-hydrophobic balance of BS mixtures may profoundly affect the early stages of CH gallstone formation.

Bile Acids and Salts↗
PubMed1978

Lecithin--cholesterol acyltransferase and the lipoprotein abnormalities of obstructive jaundice.

1. We have studied the plasma lipoprotein abnormalities in obstructive jaundice to test the hypothesis that the abnormalities would correlate with plasma lecithin--cholesterol acyltransferase activity. 2. Very-low-density lipoproteins (VLDL) were normal in composition and had a normal pre-beta electrophoretic mobility when lecithin--cholesterol acyltransferase activity was high. When it was low VLDL had abnormal composition and ran in the beta position. 3. With high lecithin--cholesterol acyltransferase activity, low-density lipoprotein (LDL) was normal and cholestatic LDL (LP-X) was not found. With low lecithin--cholesterol acyltransferase activity up to three LDL fractions were found: (i) large triglyceride-rich particles, (ii) LP-X and (iii) a triglyceride-rich cholesteryl ester-poor particle of normal dimensions. 4. High-density lipoprotein (HDL) concentrations correlated with lecithin--cholesterol acyltransferase activity and HDL were normal in composition and electron-microscopic appearance when the activity was high. When lecithin--cholesterol acyltransferase activity was low HDL was abnormal in composition and 'stacked discs' were seen on electron microscopy as well as normal spherical particles. 5. These results suggest that low lecithin-cholesterol acyltransferase activity may cause at least some of the lipoprotein changes of obstructive jaundice.

Adult↗
PubMed2003

Fat-free foods supplemented with soy stanol-lecithin powder reduce cholesterol absorption and LDL cholesterol.

OBJECTIVE: The objective of this work was to show that fat-free, lecithin-formulated soy stanols lower cholesterol absorption and serum LDL cholesterol. DESIGN: Reduction in cholesterol absorption was measured in paired single-meal tests with or without formulated soy stanols (acute test), and changes in serum lipids were investigated in a 10-week, randomized, double-blind parallel trial in which formulated stanols or lecithin vehicle were given three times daily for the last 4 weeks (chronic test). SUBJECTS/SETTING: Forty-five normal or mildly hypercholesterolemic subjects were recruited for both studies. The 21 subjects (16 female, 5 male; mean age 32.5 years) in the absorption studies had the following mean lipid values: LDL cholesterol, 2.79 mmol/L and total cholesterol, 4.73 mmol/L. For the lipid reduction, 24 subjects (16 female, 8 male; mean age 50.6 years) were enrolled with mean LDL cholesterol and total cholesterol of 3.72 mmol/L and 5.66 mmol/L, respectively. INTERVENTION: Reduction in cholesterol absorption was measured using a lemonade beverage or egg whites that contained 625 mg stanols. Throughout the chronic study, subjects followed the American Heart Association Step I diet. During the 4-week treatment phase, subjects consumed daily a lemonade-flavored beverage containing either placebo or formulated soy stanols (1.9 g). MAIN OUTCOME MEASURES: Inhibition of cholesterol absorption was determined from the difference in plasma deuterated cholesterol enrichment after a test meal containing stanol-lecithin and one with lecithin vehicle only. In the chronic study, the primary endpoints were changes in LDL and total cholesterol. STATISTICAL ANALYSES PERFORMED: Paired or unpaired t tests were used to determine statistical significance. RESULTS: Stanol-lecithin reduced cholesterol absorption by 32.1% (P=.0045, n=10) and by 38.2% (P=.0022, n=11) when delivered in a lemonade-flavored beverage and in egg whites, respectively. Reduction in cholesterol absorption was strongly related to the initial level of absorbed cholesterol tracer in serum (r(s)=-0.739). Stanol-lecithin given in a beverage reduced total serum cholesterol by 10.1% (P=.0019, n=24) and LDL cholesterol by 14.3% (P=.0016, n=24). APPLICATIONS/CONCLUSIONS: Powdered soy stanol-lecithin lowers cholesterol absorption and LDL cholesterol when consumed in fat-free foods.

Adult↗
PubMed1980

Magneto-orientation of lecithin crystals.

For the purpose of clarifying the magneto-orientation mechanism of several biological membrane systems, xylene-suspended thin-layered single crystals of lecithin, which is a major component of membranes, were subjected to magnetic fields of various strengths, and the orientation behavior of the crystals was analyzed. Lecithin crystals oriented in such a way that the directions of both the hydrocarbon chains and the phosphorylcholine group of the lecithin molecule were perpendicular to the magnetic field, suggesting that the crystals were diamagnetically biaxial. In contrast, hydrocarbon chains of phospholipids in many biological membranes are known to orient parallel to magnetic fields. The value of the volume diamagnetic susceptibility anisotropy, delta chi (i.e. the difference between susceptibilities parallel and perpendicular to the direction of the hydrocarbon chain in the lecithin crystals), estimated from the magneto-orientation behavior was about -9 X 10(-8) cgs. This is distinctly larger than that of vesicles of egg yolk lecithin measured by Boroske and Helfrich [Boroske, E. & Helfrich, W. (1978) Biophys. J. 24, 863-868] and also larger than that of single crystals of polyethylene, which was measured for comparison by the same technique as that used for lecithin in this study. The differences between these values of delta chi seem to result from the contribution of the polar head (i.e., the part of the lecithin molecule other than the two hydrocarbon chains), which is ordered, less ordered, or deleted in the respective cases above, although mainly from the contribution of the hydrocarbon chains, which are ordered in crystals and disordered in vesicles.

Crystallography↗
PubMedDate not supplied

The effect of lecithin supplementation on plasma choline concentrations during a marathon.

BACKGROUND: Previous studies have shown that plasma and urinary free choline concentrations decrease significantly during a marathon, and that these decreases may be associated with decreased performance. OBJECTIVE: In a pilot study, we sought to determine whether lecithin supplementation prior to a marathon would maintain plasma free and urinary choline concentrations and improve performance versus placebo. METHODS: 12 accomplished marathon runners, males (7) and females (5), 21 to 50 years of age were randomized to receive lecithin (4 capsules BID; PhosChol 900) or placebo beginning one day prior to the 2000 Houston-Methodist Health Care Marathon. The lecithin supplement provided approximately 1.1 g of choline on a daily basis (2.2 g total). Runners estimated finish time based on recent performance and training. Fasting, pre- and post-marathon plasma and a five-hour urine collection were analyzed for free choline and plasma for phospholipid-bound choline. Pre-race predicted, as well as the actual finish time, were recorded. RESULTS: All subjects completed the marathon. Plasma free choline decreased significantly in the placebo group and increased significantly in the lecithin group (9.6 +/- 3.6 to 7.0 +/- 3.6 nmol/mL vs. 8.0 +/- 1.2 to 11.7 +/- 3.6 nmol/mL, p = 0.001 for the delta between groups). No significant changes in plasma phospholipid-bound choline concentration were observed. There was a non-significant decrease in urine free choline in both groups. Actual finish time was 256.3 +/- 46.3 minutes for the lecithin group vs. 240.8 +/- 62.0 for the placebo group and the actual:predicted time was 1.03 +/- 0.06 (lecithin) and 1.07 +/- 0.08 (placebo), p = 0.36. CONCLUSION: Short-term lecithin supplementation prior to a marathon maintains normal plasma free choline concentration during the race, but failed to improve performance.

Adult↗
PubMed2005

Cholesterol intake is associated with lecithin intake in Japanese people.

Many dietary recommendations for the prevention of heart disease and hyperlipidemia include restriction of cholesterol intake. However, limiting cholesterol intake might also affect the intake of other nutrients. The daily intakes of cholesterol, lecithin, total fatty acids, and SFAs by 388 Japanese subjects (ages 6-59 y) were analyzed directly using the duplicate portion sampling technique. Intakes were 266.1 +/- 146.5 mg/d, 1.6 +/- 0.9 g/d, 39.3 +/- 16.8 g/d, and 12.8 +/- 6.9 g/d, respectively. There was a strong positive correlation between cholesterol and lecithin intakes (r = 0.864, P < 0.001), and when food intake was adjusted to 1 kg/d, the correlation remained high (r = 0.881, P < 0.001). In contrast, the correlation between total fatty acid and lecithin intakes was lower (r = 0.423, P < 0.001), and when food intake was adjusted to 1 kg/d, the correlation coefficient remained stable (r = 0.448, P < 0.001). These results strongly indicate that limiting cholesterol intake decreases lecithin intake. Lecithin intake can be estimated from the following regression equation: lecithin intake (g/d) = 0.005 x cholesterol intake (mg/d) + 0.16 (R2= 0.747, P < 0.001). Furthermore, the intake of choline derived from lecithin can be estimated by the following equation: choline (mg/d) = 0.724 x cholesterol (mg/d) + 21.5.

Adult↗
PubMed1997

A binding study of phospholipase A2 with lecithin, lysolecithin and their tetrahedral intermediates using molecular modeling.

We used molecular modeling to examine the binding of 1,2-dioctanoyl-sn-glycero-3-phosphocholine (a lecithin), 1-octanoyl-sn-glycero-3-phosphocholine (a lysolecithin) and their tetrahedral intermediates in the catalytic site of phospholipase A2 (PLA2). We performed energy minimization on each complex, computed the binding energy, determined the relative binding energy among the complexes and calculated the difference in inter- and intramolecular energies of the components in the complexes. We found that the calculated orientation of the sn-1 ester bond of lysolecithin in the active site is similar to that of the sn-2 ester bond in lecithin, thus permitting PLA2 to hydrolyze lysolecithin using the same mechanism as it uses to hydrolyze lecithin. On the other hand, the binding of lecithin is energetically more favorable by 4.5 kcal/mol than the binding of lysolecithin to the enzyme, and the binding of the lecithin tetrahedral intermediate is also energetically more favorable by 19.7 kcal/mol than the binding of the lysolecithin tetrahedral intermediate to the enzyme, which explains why lecithin is a better substrate than lysolecithin in the catalytic site. These results indicate that the activation energy for the hydrolysis of lysolecithin is higher than that for lecithin, consistent with the observed slower rate for the hydrolysis of lysolecithin.

Animals↗
PubMed1990

The behavior of proteases in lecithin reverse micelles.

Reverse micelles, formed in isooctane/alcohol by phosphatidylcholines of variable chain length (i.e. 6, 7 or 8 C atoms in the fatty acid moiety) have been studied, mostly in relation to their capability of solubilizing trypsin and alpha-chymotrypsin. It has been found that the capability of the lecithin reverse micellar systems to solubilize water is strongly affected by the chain length of the alkyl group and by the alcohol used as co-surfactant. The C8-lecithin system, i.e. 1,2-dioctanoyl-sn-glycero-3-phosphocholine, in isooctane/hexanol is the system which affords the maximal solubilization of water (up to wo 60, where wo = [H2O]/[lecithin]) and of the enzymes. The water of the water pool of lecithin reverse micelles has been investigated by 1H-NMR; the proton chemical shift as a function of wo was found to be similar to the case of reverse micelles formed by the well known negatively charged surfactant sodium bis(2-ethylhexyl sulfosuccinate). 31P-NMR studies show that the ionization behavior of phosphate groups is similar to that in bulk water, suggesting no anomaly in the pH behavior of this water pool. The stability of trypsin and alpha-chymotrypsin in the various lecithin reverse micellar system is similar and occasionally better than that in aqueous solution. The same holds for the kinetic behavior (kcat and Km have been determined for a few systems). The bell-shaped curve of the pH/activity profile in lecithin reverse micelles is, for both enzymes, shifted towards more alkaline values with respect to water. Bell-shaped curves are also obtained when studying the influence of wo on the enzyme activity, with an optimal wo which is in the range 7-10, a surprisingly small value considering that we are dealing with hydrolases. Circular dichroic studies have been carried out in order to correlate the activity with the protein conformation: for both enzymes, generally no marked perturbations appear as a consequence of the solubilization in the lecithin reverse micelles, but conditions can be found under which significant alterations are present. Certain properties of the two enzymes, which in water solution are very similar, become sharply different in reverse micelles, showing that occasionally the micellization is able to enhance the relatively small structural differences between the two proteins.

Chymotrypsin↗
PubMed1972

Biliary excretion of lecithin and cholesterol in the dog.

The biliary excretion rates of bile acid, lecithin, and cholesterol were measured in unanesthetized dogs after interruption of enterohepatic circulation and during infusions of sodium taurocholate, sodium glycocholate, sodium dehydrocholate, SC2644 (a bicyclic organic acid with high choleretic potency), and secretin. Both lecithin output and cholesterol output were directly related to bile acid excretion rate. The curves describing these relationships were concave downward. Molar concentration ratios of lecithin-to-bile acid declined gradually from approximately 0.4 to 0.2 as bile acid output increased from approximately 1 to 70 mumoles/min. Cholesterol-to-lecithin molar ratios were highest (0.05-0.15) at very low rates of bile acid excretion, but descended rapidly to a plateau (0.03-0.04) which was constant over the entire range of bile acid excretion rates from 10 to 70 mumoles/min. Similar lipid excretion patterns were observed during glycocholate infusion, but secretin-induced choleresis and dehydrocholate-induced choleresis were unaccompanied by any increments in lecithin or cholesterol excretion and SC2644 (which caused a marked increase in canalicular bile production as measured by erythritol clearance) caused a depression of lipid excretion. The data are consistent with the view that lecithin moves passively from cell membranes to intracanalicular micelles, that transport of cholesterol is coupled to lecithin transport, and that there is also a small amount of independent passive transport of cholesterol from membranes to micelles. A model developed on these assumptions has been shown to behave in a fashion consistent with the entire range of these observations.

Animals↗
PubMed1994

Contents of lecithin and choline in crude drugs.

The determination of lecithin and choline in crude drugs was established by a combination of high performance liquid chromatography (HPLC) with electrochemical detector (ECD) and enzyme reaction. Lecithin in crude drugs extracted with a mixture of chloroform-methanol (2:1) at room temperature was hydrolyzed by phospholipase D. The hydrolyzate was injected to HPLC, and choline was separated from impurities by reverse phase column. The choline was converted to betaine and hydrogen peroxide by passing through column packed with immobilized choline oxidase. This hydrogen peroxide was detected by ECD. The peak area of hydrogen peroxide derived from lecithin was proportional to the concentration of lecithin from 0.10 to 1.52 microgram/ml. Choline in crude drugs was extracted with ethanol under reflux and determined under the same HPLC conditions as lecithin. The peak area of hydrogen peroxide derived from choline was proportional to the concentration of choline from 0.01 to 0.45 microgram/ml. The contents of lecithin and choline in 31 kinds of crude drugs were determined by these established methods. The results showed that Cervi Parvum Cornu, Kokurozin, Foenigraeci Semen and Psoraleae Semen contained more lecithin than other crude drugs, while Angelicae Radix, Foenigraeci Semen, Psoraleae Semen, and especially Hippocampus were found to contain more choline than other crude drugs.

Choline↗
PubMed1982

Lecithin: cholesterol acyl transfer rate in hypothyroidism and hyperthyroidism.

The initial rate of lecithin: cholesterol acyl transferase and serum concentration of lipids were determined in euthyroid, hypothyroid and hyperthyroid subjects. In hyperthyroid subjects, the serum levels of total and free cholesterol were significantly lower than in normal subjects and the fractional lecithin: cholesterol acyl transfer rate was significantly higher than in normal subjects. The molar lecithin: cholesterol acyl transfer rate was also higher than in normal subjects, but not significantly. The free cholesterol/total cholesterol ratio in hypothyroid females and the serum levels of triglyceride and free fatty acid in hypothyroid male were significantly higher than in normal subjects. The fractional lecithin: cholesterol acyl transfer rates in hypothyroid females were significantly lower than in normal females. After treatment of the thyroid disease the fractional and molar lecithin: cholestorol cholesterol acyl transfer rate approached the normal values. There was a positive correlation between fractional and molar lecithin: cholesterol acyl transfer rate and thyroxine. These results suggest that thyroid hormone influences the cholesterol esterification through the activation of lecithin: cholesterol acyltransferase.

Adult↗
PubMed1987

Lactation response to short-term abomasal infusion of choline, inositol, and soy lecithin.

Five lactating Holstein cows averaging 13 wk postpartum were used in a Latin square design to examine the effect of daily abomasal infusion of choline (22 g), myo-inositol (37 g), soy oil (325 ml), or crude soy lecithin (900 ml) on lactation performance. Dry matter intake was reduced by infusion of soy lecithin as compared with infusion of water (18.1 and 21.1 kg/d, respectively). Plasma beta-hydroxybutyrate concentration was increased when cows received the myo-inositol or soy lecithin infusion, and plasma glucose was lower when cows received the choline or soy lecithin treatment. Infusion of soy lecithin caused approximately a twofold increase in plasma triglyceride-rich lipoprotein concentration. Milk fat percentage and milk fat yield were greater during soy lecithin infusion (3.54%, 1.11 kg/d) than during water (3.09%, .98 kg/d) or soy oil (3.06%, .98 kg/d) infusion. This resulted in greater 3.5% FCM yield during soy lecithin infusion (31.6 kg/d) than during water (29.5 kg/d) or soy oil (29.6 kg/d) infusion. Infusion of phospholipid with triglyceride allowed more fatty acid to be infused without causing diarrhea. Infusion of triglyceride in the presence of phospholipid increased milk fat synthesis whereas infusion of triglyceride alone did not.

Abomasum↗
PubMed1975

Risk of respiratory distress syndrome as determined by amniotic fluid lecithin concentration.

Lecithin concentration has been determined in 476 samples of amniotic fluid collected within 72 hours of delivery. If delivery is associated with a level of lecithin of 0.100 mg/100 ml. of lecithin phosphorus or greater, the risk of RDS in the neonate is minimal, if any. If delivery is associated with a level of lecithin less than 0.100 mg/100 ml. of lecithin phosphorus, a definite risk of RDS is present. This "risk factor" is a function of the lecithin concentraion and may be expressed in terms of a simple mathematical equation. The equation, log y equals minus 1.0187 minus 0.0101 chi, expresses the relationship in a highly significant manner (r equals 0.99) where y equals lecithin concentration and chi equals risk of RDS. In managing individual high-risk patients, our general policy is to weigh the chemically determined "risk factor" of RDS if delivery is done against the clinically determined "risk factors" involved if delivery is delayed. By comparing the various risks involved, appropriate management is decided upon.

Amniocentesis↗
PubMed1985

Activation of lecithin: cholesterol acyltransferase by human apolipoprotein A-IV.

Human plasma apoproteins (apo) A-I and A-IV both activate the enzyme lecithin:cholesterol acyltransferase (EC 2.3.1.43). Lecithin:cholesterol acyltransferase activity was measured by the conversion of [4-14C] cholesterol to [4-14C]cholesteryl ester using artificial phospholipid/cholesterol/[4-14C]cholesterol/apoprotein substrates. The substrate was prepared by the addition of apoprotein to a sonicated aqueous dispersion of phospholipid/cholesterol/[4-14C]cholesterol. The activation of lecithin:cholesterol acyltransferase by apo-A-I and -A-IV differed, depending upon the nature of the hydrocarbon chains of the sn-L-alpha-phosphatidylcholine acyl donor. Apo-A-I was a more potent activator than apo-A-IV with egg yolk lecithin, L-alpha-dioleoylphosphatidylcholine, and L-alpha-phosphatidylcholine substituted with one saturated and one unsaturated fatty acid regardless of the substitution position. When L-alpha-phosphatidylcholine esterified with two saturated fatty acids was used as acyl donor, apo-A-IV was more active than apo-A-I in stimulating the lecithin:cholesterol acyltransferase reaction. Complexes of phosphatidylcholines substituted with two saturated fatty acids served as substrate for lecithin:cholesterol acyltransferase even in the absence of any activator protein. Essentially the same results were obtained when substrate complexes (phospholipid-cholesterol-[4-14C]cholesterol-apoprotein) were prepared by a detergent dialysis procedure. Apo-A-IV-L-alpha-dimyristoylphosphatidylcholine complexes thus prepared were shown to be homogeneous particles by column chromatography and density gradient ultracentrifugation. It is concluded that apo-A-IV is able to facilitate the lecithin:cholesterol acyltransferase reaction in vitro.

Apolipoprotein A-I↗
PubMed1982

A simplified medium for detecting the effect of lecithin on the growth of Propionibacterium acnes.

Thirty strains of Propionibacterium acnes were assayed to detect the effect of lecithin on their growth and to test the nutritional requirement of this bacterium for this phospholipid. The liquid lecithin medium (LLM) and solid lecithin medium (SLM), containing purified bovine lecithin (PBL) supported the growth of P. acnes strains assayed. Two percent PBL, which was an optimal concentration of lecithin (w/v in LLM and SLM) for the normal growth of P. acnes, was found to be inhibitory for the growth of a strain of Staphylococcus aureus tested. the growth of P. acnes in lecithin media was consistently comparable to the growth patterns of P. acnes in complex media. These results indicated that lecithin in lower concentrations than 2% stimulated the growth of P. acnes. There was an indication that this bacterium may produce enzymes capable of hydrolyzing this phosphoglyceride, incorporated in a defined basal medium, to use it as a source of carbon, energy and fatty acids.

Culture Media↗