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At least 667 records · Page 37Linked to original sources
PubMed1976

Follow-up study of a case of generalized ceroidlipofuscinosis of childhood with special reference to the finding of an abnormal serum lecithin fatty acid pattern.

In quest of a more precise and stringent diagnosis for a case of generalized ceroidlipofuscinosis the patient was reexamined and additional laboratory tests were performed. For the third time myeloperoxidase activity was normal. On two separate occasions the serum lecithin fatty acid pattern was found to be abnormal and to resemble closely the pattern reported to be characteristic of polyunsaturated fatty acid lipidosis. The tau fraction was measured on one occasion and found to be normally present. Head circumference was confirmed to be normal. Pigmentary retinal changes were observed by fundoscopic examination. The child had prominent epileptic activity in form of myoclonic jerks. The case does not fit exactly into the picture reported recently for children with polyunsaturated fatty acid lipidosis. Doubt is voiced that these children have other than an infantile type of generalized ceroidlipofuscinosis. Thus, for the time being we regard ours as a case of generalized ceroidlipofuscinosis of infantile onset with an abnormal serum lecithin fatty acid composition. Furthermore, it seems to us that the infantile form, in the same manner and to the same extent as the late infantile and juvenile forms, does not constitute an entirely homogeneous group within the ceroidlipofuscinoses.

Arachidonic Acids↗
PubMed1985

Fatty acid composition of serum lecithin and cholesterol ester in the normal menstrual cycle.

Gonadal hormones and the relative fatty acid composition of serum lecithin and cholesterol ester were studied on four occasions during one cycle in twenty-two regularly menstruating women. The most evident change during the menstrual cycle was a decrease in the sum of polyunsaturated fatty acids of the linoleic series in the late luteal phase. Concomitantly an increase in oleic acid as well as palmitic acid was recorded. These changes were considered to be dietary influenced since a shift of the oleic/linoleic acid ratio is often seen when fat is replaced by sugar and some women are known to increase their intake of refined carbohydrates premenstrually. The only correlation found for fatty acids and hormone levels was a correlation of the ratio oleic/linoleic acids and 17-beta-estradiol. This pattern is not seen after administration of exogenous estrogens and obviously there is a discrepancy between endogenous and exogenous estrogens in this context. Whether physiological fluctuations of sex hormones during the menstrual cycle directly influence the fatty acid composition of serum lecithin and cholesterol ester is uncertain. No changes in dihomo-gamma-linolenic acid or arachidonic acid, the major precursors of prostaglandin synthesis were recorded.

Adolescent↗
PubMed1969

Orientation of lipid spin labels in lecithin multilayers.

Nitroxide-labeled stearic acid and cholestane have been incorporated into lecithin multilayers. The pronounced anisotropy of the preparations reflects a nonrandom structure of the lecithin film and demonstrates that these lipid probes can report structural information from lipid regions resembling those thought to occur in membranes. These two probes differ with respect to the orientation of the NO bond to the long axis, but both orient with their long axes perpendicular to the phospholipid film. Simulated spectra, calculated on the basis of a Gaussian distribution of orientations, are in agreement with the experimental results.

Electron Spin Resonance Spectroscopy↗
PubMed1975

Apparent dependence of interactions between cytochrome b5 and cytochrome b5 reductase upon translational diffusion in dimyristoyl lecithin liposomes.

Dimyristoyl lecithin liposomes, containing cytochrome b5 reductase (NADH:ferricytochrome b5 oxidoreductase, EC 1.6.2.2) and varying amounts of cytochrome b5, were used to measure flavoprotein catalysis alone and catalysis requiring electron transfer between the reductase and cytochrome as a function of temperature. Whereas flavoprotein catalysis showed a simple linear temperature dependence in an Arrhenius plot, the reaction involving electron transfer between the two bound enzymes showed a marked, 4-fold, change in rate at the crystalline-liquid crystalline phase transition of the hydrocarbon chains of the lecithin vesicles and a second, minor change involving the minor transition. These data represent strong evidence that protein-protein interactions in this membrane model system are dependent upon translational diffusion of nonpolar segments of the proteins in the hydrocarbon region of the phospholipid bilayer.

Animals↗
PubMed1991

A molecular defect causing fish eye disease: an amino acid exchange in lecithin-cholesterol acyltransferase (LCAT) leads to the selective loss of alpha-LCAT activity.

Epidemiological as well as biochemical evidence of recent years has established that a low plasma level of high density lipoprotein-cholesterol is a predictor for the risk of coronary artery disease. However, there is a heterogeneous group of rare familial disorders, characterized by severe high density lipoprotein deficiency, in which the predicted increased risk is not clearly apparent. One such disorder has been called fish eye disease to reflect the massive corneal opacification seen in these patients. In this report, we describe the biochemical and genetic presentation of two German fish eye disease homozygotes and their family members. Vertical transmission of a decrease in the specific activity of lecithin-cholesterol acyltransferase (EC 2.3.1.43) indicated that this enzyme was a candidate gene for harboring the defect responsible for this disorder. Direct sequencing of DNA segments amplified by the polymerase chain reaction (PCR) that encode the exons of the lecithin-cholesterol acyltransferase gene led to the identification of a homozygous mutation resulting in the substitution of threonine at codon 123 for an isoleucine residue in both individuals. Family analysis in an extended pedigree was used to establish a causal relationship between this mutation and the biochemical phenotype for fish eye disease. The homozygous presence of this mutation in two phenotypically homozygous members of an unrelated Dutch family with fish eye disease further supports this finding.

Aged↗
PubMed2002

Enhancement of scavenger receptor class B type I-mediated selective cholesteryl ester uptake from apoA-I(-/-) high density lipoprotein (HDL) by apolipoprotein A-I requires HDL reorganization by lecithin cholesterol acyltransferase.

The severe depletion of cholesteryl ester (CE) in adrenocortical cells of apoA-I(-/-) mice suggests that apolipoprotein (apo) A-I plays an important role in the high density lipoprotein (HDL) CE selective uptake process mediated by scavenger receptor BI (SR-BI) in vivo. A recent study showed that apoA-I(-/-) HDL binds to SR-BI with the same affinity as apoA-I(+/+) HDL, but apoA-I(-/-) HDL has a decreased V(max) for CE transfer from the HDL particle to adrenal cells. The present study was designed to determine the basis for the reduced selective uptake of CE from apoA-I(-/-) HDL. Variations in apoA-I(-/-) HDL particle diameter, free cholesterol or phospholipid content, or the apoE or apoA-II content of apoA-I(-/-) HDL had little effect on HDL CE selective uptake into Y1-BS1 adrenal cells. Lecithin cholesterol acyltransferase treatment alone or addition of apoA-I to apoA-I(-/-) HDL alone also had little effect. However, addition of apoA-I to apoA-I(-/-) HDL in the presence of lecithin cholesterol acyltransferase reorganized the large heterogeneous apoA-I(-/-) HDL to a more discrete particle with enhanced CE selective uptake activity. These results show a unique role for apoA-I in HDL CE selective uptake that is distinct from its role as a ligand for HDL binding to SR-BI. These data suggest that the conformation of apoA-I at the HDL surface is important for the efficient transfer of CE to the cell.

Animals↗
PubMed2003

Compared with Acyl-CoA:cholesterol O-acyltransferase (ACAT) 1 and lecithin:cholesterol acyltransferase, ACAT2 displays the greatest capacity to differentiate cholesterol from sitosterol.

The capacity of acyl-CoA:cholesterol O-acyltransferase (ACAT) 2 to differentiate cholesterol from the plant sterol, sitosterol, was compared with that of the sterol esterifying enzymes, ACAT1 and lecithin:cholesterol acyltransferase (LCAT). Cholesterol-loaded microsomes from transfected cells containing either ACAT1 or ACAT2 exhibited significantly more ACAT activity than their sitosterol-loaded counterparts. In sitosterol-loaded microsomes, both ACAT1 and ACAT2 were able to esterify sitosterol albeit with lower efficiencies than cholesterol. The mass ratios of cholesterol ester to sitosterol ester formed by ACAT1 and ACAT2 were 1.6 and 7.2, respectively. Compared with ACAT1, ACAT2 selectively esterified cholesterol even when sitosterol was loaded into the microsomes. To further characterize the difference in sterol specificity, ACAT1 and ACAT2 were compared in intact cells loaded with either cholesterol or sitosterol. Despite a lower level of ACAT activity, the ACAT1-expressing cells esterified 4-fold more sitosterol than the ACAT2 cells. The data showed that compared with ACAT1, ACAT2 displayed significantly greater selectively for cholesterol compared with sitosterol. The plasma cholesterol esterification enzyme lecithin:cholesterol acyltransferase was also compared. With recombinant high density lipoprotein particles, the esterification rate of cholesterol by LCAT was only 15% greater than for sitosterol. Thus, LCAT was able to efficiently esterify both cholesterol and sitosterol. In contrast, ACAT2 demonstrated a strong preference for cholesterol rather than sitosterol. This sterol selectivity by ACAT2 may reflect a role in the sorting of dietary sterols during their absorption by the intestine in vivo.

2-Hydroxypropyl-beta-cyclodextrin↗
PubMed1985

The influence of creatinine, lecithin and choline feeding on aliphatic amine production and excretion in the rat.

The excretion of aliphatic amines, methylamine, dimethylamine and trimethylamine in the urine and faeces of rats fed on a control diet and diets supplemented with creatinine, lecithin or choline were measured over a 14 d feeding period. The rats were then killed and concentrations of amines in small and large intestinal contents measured. Adding creatinine to the diet resulted in a significant increase of methylamine excretion in the faeces and urine. The amount of methylamine found in all parts of the intestine increased, especially in the caecum. Adding lecithin to the diet resulted in an increase in the methylamine excretion only, and no change in the concentrations of amines found in the intestine, except for trimethylamine which was significantly increased in the caecum and colon. Adding choline to the diet resulted in a significant increase in excretion of trimethylamine and, to a lesser extent, methylamine. The levels of amines found in the gut increased, dimethylamine being increased in the small bowel, and methylamine and trimethylamine in the caecum.

Animals↗
PubMedDate not supplied

Effects of chronic choline and lecithin on mouse hippocampal dendritic spine density.

Dendritic spines, which project from the dendrites of central neurons, are thought to contribute to the amount of contact area available for synaptic connections. The density of these spines has been found to correlate with learning and memory function, and there is a progressive decrease in dendritic spine density with aging. In addition, experimental animals given a choline-enriched diet have an increase in neocortical spine density compared to controls. In this study, the dendritic spine density of hippocampal pyramidal cells was examined in aged mice which had received life-long choline enriched, choline deficient or lecithin enriched diets. These treatments had no effect on hippocampal dendritic spine density compared to control. The results indicate that dietary supplementation may have different effects in different brain areas and that the relative increase in learning and memory function in aged animals given a choline or lecithin enriched diet is not due to an increase in hippocampal dendritic spine density.

Aging↗
PubMed1993

Ionizing radiation target groups of band 3 inserted into egg lecithin liposomes as determined by Raman spectroscopy.

The purified integral membrane protein, band 3, from human erythrocytes was inserted into egg lecithin liposomes. The insertion of band 3 was determined from thermal transition data from the analysis of the C--H stretching region bands recorded at temperatures from 25 to -22 degrees C. Raman spectra show that band 3 considerably broadens and lowers the thermal transition of egg lecithin liposomes, suggesting the insertion of band 3. The band 3-inserted liposomes were irradiated with gamma-rays (40 Gy) and the radiation target groups were determined by the analysis of the structural sensitive Raman bands in the 1600-1700 cm-1 (amide I), 1200-1300 cm-1 (amide III) and 550-1030 cm-1 (side chain amino groups) regions. The radiation-sensitive groups as identified from Raman spectra in the region 550-1030 cm-1 are tyrosines and cysteines. The radiation-induced changes in the secondary structure were determined from amide I and III bands. Quantitative estimation using the curve fitting method shows that band 3 contains 44% total helix, 48% beta strand and 8% undefined plus turns (error +/- 4%). The secondary structure changes to 35% total helix, 42% total beta-strand and 23% turned and undefined upon irradiating band 3 containing liposomes. We suggest that ionizing radiation preferably damages tyrosine and cysteine side chain residues and reduces the amount of alpha-helical configuration of band 3.

Anion Exchange Protein 1, Erythrocyte↗
PubMed2004

Effects of soy lecithin phosphatidic acid and phosphatidylserine complex (PAS) on the endocrine and psychological responses to mental stress.

Phosphatidylserine, derived from cow brains, has been shown previously to dampen the ACTH and cortisol response to physical stress. Further research investigated the influence of soy lecithin phosphatidylserine supplementation on mood and heart rate when faced with an acute stressor. In this study, we investigated the effects of soy lecithin phosphatidic acid and phosphatidylserine complex (PAS) supplementation on pituitary adrenal reactivity (ACTH, cortisol) and on the psychological response (Spielberger State Anxiety Inventory stress subscale) to a mental and emotional stressor. Four groups of 20 subjects were treated for three weeks with daily dosages of either 400 mg PAS, 600 mg PAS, 800 mg PAS, or placebo before exposure to the Trier Social Stress Test (TSST). Treatment with 400 mg PAS resulted in a pronounced blunting of both serum ACTH and cortisol, and salivary cortisol responses to the TSST, but did not affect heart rate. The effect was not seen with larger doses of PAS. With regard to the psychological response, 400 mg PAS seemed to exert a specific positive effect on emotional responses to the TSST. While the placebo group showed the expected increase in distress after the test, the group treated with 400 mg PAS showed decreased distress. These data provide initial evidence for a selective stress dampening effect of PAS on the pituitary-adrenal axis, suggesting the potential of PAS in the treatment of stress related disorders.

Adrenocorticotropic Hormone↗
PubMed2002

Lecithin microemulsions in dimethyl ether and propane for the generation of pharmaceutical aerosols containing polar solutes.

Water soluble compounds have been incorporated into solution phase metered dose inhalers (MDIs) utilizing lecithin inverse microemulsions in dimethyl ether (DME) and propane. DME and propane acted as both solvent and propellant. Experiments utilizing model propellants (dimethylethyleneglycol (DMEG) and hexane) were used to investigate microemulsion physicochemical phenomena, and the results were used to design and interpret the technically more challenging MDI experiments. NMR and viscosity experiments with model propellants were consistent with a "sphere-to-string" micellar shape change as the solvent was varied from pure DMEG to pure hexane. Water soluble solutes, including selected peptides and fluorescently labeled poly-alpha, beta-[N-(2-hydroxyethyl) D,L-aspartamide] (fPHEAs), dissolved in DME/propane dependent on lecithin and water content. MDIs containing microemulsions generated aerosols with mass median aerodynamic values ranging from 2.7 to 3.1 microns, within the range of commercially available formulations. Fine particle fraction values (50-70%) exceeded those of commercial formulations. fPHEA up to 18 kDa did not adversely affect the aerosol characteristics. Deposition of the aerosol onto a water surface resulted in the formation of liposomes with partially entrapped solute.

Aerosol Propellants↗
PubMed1976

Incorporation of newly formed lecithin into peripheral nerve myelin.

Radioactive choline was used to study the metabolism and movement of choline-containing phospholipids in peripheral nerve myelin of adult mice. Incorporation at various times after intraperitoneal injection was measured in serial segments of sciatic nerve as well as in myelin isolated from those segments. At no time (1 h to 35 days) could a proximal-distal difference in the extent of labeling be demonstrated. This finding suggests that incorporation of precursor choline phospholipids into nerve membranes is a local event, with little contribution from the neuronal perikaryon via axoplasmic transport. Autoradiographic investigations were undertaken to elucidate the pattern of movement of radioactive choline-labeled phospholipids, predominantly lecithin, into the myelin sheaths of the sciatic nerve. A sequence of autoradiographs was prepared from animals sacrificed between 20 min and 35 days after a microinjection of precursor directly into the nerve. Analysis of these autoradiograms revealed that labeling is initially concentrated in the Schwann cell cytoplasm. Later, the label moves first into the outer regions of the myelin sheaths and is eventually distributed evenly throughout the inner and outer layers of the sheath. At no time is there a build-up of label in the axon. The rate of uptake of precursor and subsequent redistribution of lecithin into the myelin were also examined in frog sciatic nerve (18 degrees C). Both uptake and redistribution processes were considerably slower in the cold-blooded animal.

Animals↗
PubMed1974

Ion diffusion selectivity in lecithin-water lamellar phases.

The diffusion coefficients of Na(+), Rb(+), and cl(-) were determined in lecithin-water lamellar phases at 18 degrees C as a function of phase hydration. Diffusion was measured within the phase with no transfer between phase and bulk aqueous medium. The relative diffusion coefficients of anion and cation depended strongly on phase hydration. At low water content, the diffusion coefficient of Cl(-) was greater than that of Na(+) or Rb(+) whereas at high water content both cations diffused faster than the anion. The change in relative diffusion coefficient occurred at 0.24 g water/g phase (24% water). The possibility that a change in conformation of the lecithin polar head occurs at a phase water content of 24% is considered. The diffusion coefficients of all three ions decreased at the water content where the relative diffusion rates inverted. Freeze fracture and polarizing microscopy studies were carried out to obtain information on phase structure. The latter study indicated that a change in long-range organization of the phase occured at 24% water. This change accounts for the decrease in the ion diffusion coefficients at this water content. The change in conformation of the choline phosphate group proposed as an explanation for the change in ion selectivity could lead to changes in long-range organization of the phase as a second order-effect.

Chlorides↗
PubMed1978

Diffusion within egg lecithin bilayers resembles that within soft polymers.

An analysis is presented of how the permeability coefficient/octanol:water partition coefficient ratio for 33 different chemical substances crossing egg lecithin bilayers depends on the molecular volume of the substances. From this analysis we conclude that bilayers made from egg lecithin behave as soft polymers in their discrimination between permeants of different sizes and shapes.

Diffusion↗
PubMed1997

Lecithinized superoxide dismutase: an inhibitor of human immunodeficiency virus replication.

Superoxide dismutase (SOD) is an enzyme used in the treatment of oxygen radical-related diseases. Lecithinization of SOD enhances its pharmacological activity. Lecithinized SOD (PC-SOD) inhibits human immunodeficiency virus (HIV) types 1 and 2 in MT-4 cells. HIV-1-infected MT-4 cells were cultured for 5 days in the presence of PC-SOD, at various concentrations. In an MTT assay, reverse transcriptase (RT) activity of the cell extract and p24 antigen production were measured. Untreated, HIV-1-infected MT-4 cells served as control. PC-SOD inhibited viral replication most effectively at 2500 U/ml, a concentration that did not affect cell viability, with an EC50 value of 718 U/ml. PC-SOD treatment inhibited RT activity and p24 production in a dose-dependent manner. Western blot analysis of the HIV-1-infected MT-4 cells treated with PC-SOD at 2500 U/ml did not detect any expression of viral proteins. Failure to inhibit virus adsorption, proviral DNA and mRNA synthesis, and RT and proteinase enzyme activity suggests that the mechanism of action of PC-SOD is entirely different from those of the currently available anti-HIV drugs. PC-SOD shows synergistic interaction with AZT, ddI, ddC, KNI-272, and dextran sulfate. PC-SOD also inhibited the oxidative stress-induced depletion of sulfhydryls, which are the cause of diminished antioxidant defenses in HIV-infected patients.

Anti-HIV Agents↗
PubMed1996

Effects of lecithinized superoxide dismutase on rat spinal cord injury.

Although superoxide dismutase (SOD) has been reported to promote functional recovery in ischemic spinal cord injury, it presents many difficulties in practical use primarily due to its short half-life in vivo and low tissue affinity. In this study, we investigated the effects of a new type of SOD, a lecithinized superoxide dismutase (PC-SOD), on motor disturbances, spinal cord edema, levels of myeloperoxidase (MPO), and spinal cord blood flow (SCBF) after spinal cord injury (SCI) in rats. PC-SOD is reported to show a delayed plasma disappearance in vivo in rats and has a higher affinity for vascular endothelium cells, neutrophils, and other cells than unmodified SOD. PC-SOD (4000 units/kg), unmodified SOD (4000 units/kg), or vehicle was injected intravenously 30 min after SCI. Four hours after SCI, SOD activities in spinal cord tissue and plasma were significantly higher in the PC-SOD group than in the unmodified SOD group. In the PC-SOD-treated rats, motor function was significantly better than in the other 2 groups of rats. PC-SOD significantly suppressed MPO activity, an indicator of neutrophils infiltration, in the spinal cord, at 4, 8, and 24 h after SCI, and spinal cord edema at 24 h after SCI. Moreover, the decrease of SCBF after SCI was less marked in the PC-SOD group. The present results suggest that lecithinization can improve the drug delivery of SOD to the spinal cord and PC-SOD may be an alternative pharmacological treatment for SCI.

Animals↗
PubMed1981

Plasma lecithin: cholesterol acyltransferase in copper-deficient rats.

Some groups of people with high risk of ischemic heart disease have low lecithin:cholesterol acyltransferase activity in plasma and vice versa. Because we hypothesized a relationship between inadequate copper nutriture and the risk of ischemic heart disease, we measured plasma lecithin: cholesterol acyltransferase in copper deficient male Sprague-Dawley rats. Deficiency was verified by the presence of anemia, hypercholesterolemia and low copper concentrations in kidney and skeletal muscle. Three experiments showed a significant decrease (22-32% reduction) in enzyme activity in deficiency. Copper may be required for the synthesis of the enzyme or as a constituent of the enzyme.

Animals↗