References: Lecithin
Anat Rec. 1996 Feb;244(2):175-81.
In vivo uptake of lecithin-coated polystyrene beads by rat hepatocytes and sinusoidal endothelial cells.
Kanai M, Murata Y, Mabuchi Y, Kawahashi N, Tanaka M, Ogawa T, Doi M, Soji T, Herbert DC.
Department of Anatomy, Nagoya City University Medical School, Japan.
BACKGROUND: While phagocytosis by Kupffer cells (stellate perisinusoidal macrophages) is well known and that by endothelial cells also is thought to occur under certain conditions, the uptake of large particles by hepatocytes has not been well studied. We reported previously the selective phagocytic uptake of material by hepatocytes using egg lecithin-coated silicon particles. In the present work, we describe more precisely this process following the injection of lecithin-coated polystyrene beads. Additionally, we consider the possible significance of the transcytotic action by endothelial cells. METHODS: Polystyrene latex beads (240 nm in diameter) composed of two layers of polystyrene and methyl methacrylate with a central void cavity and diameter of 140 nm were injected into male Wister-Imamichi rats. The injections were administered through the hepatic portal vein in a volume of 3 ml (concentration of the lecithin-coated or uncoated beads was 2 mg/ml). Controls received the lecithin alone at a concentration of 2 mg/ml. Liver samples were taken 5, 10, or 15 min after injection, fixed, and processed for ultrastructural analysis. RESULTS: Both lecithin-coated and noncoated beads were mainly incorporated in the Kupffer cells as well as in the endothelial cells. Bristle-coated invaginations were observed in the uptake by both cell types; however, noncoated invaginations were also active in the endothelial cells, especially on the surface facing the perisinusoidal space of Disse. Only coated beads were observed within the space or in the hepatocytes. Once taken up by the hepatocytes, the lecithin-coated beads were found either within lysosomes or in a free state in the cytoplasm. CONCLUSIONS: Up
Clin Physiol Biochem. 1993;10(1):8-12.
Acute phase proteins and plasma lipoproteins during antimony treatment in infantile visceral leishmaniasis.
Kallel R, Bekaert ED, Dubois DY, Alcindor LG, Ayrault-Jarrier M, Mebazza A.
Laboratoire de Biochimie, CHU La Rabta, Tunis, Tunisia.
The purpose of this study was to determine the effects of antimony treatment on the altered lipoprotein system of four young Tunisians with visceral Leishmaniasis and to further investigate possible relationships between acute phase proteins (C-reactive protein and apolipoprotein SAA)-known to be increased in this disease-and lipid or apolipoprotein (apo) parameters measured before and throughout the treatment. A marked improvement of all investigated parameters was already observed after the first cure: the lecithin-cholesterol acyltransferase activity was the only parameter remaining deficient even at the end of the second cure. Statistical analysis reveals a significant inverse relationship between changes in C-reactive protein and changes in the plasma ratio of esterified to total cholesterol (r = -0.78; p < 0.001) as well as in plasma apoA-I concentration (r = -0.64; p < 0.01). Because no such correlation could be observed with apoSAA, results of this study suggest that the major mechanism of lowering the plasma levels of apoA-I and the plasma-cholesteryl content could be closely related to the appearance of large amounts of C-reactive protein in plasma or more likely to the process inducing the hepatic synthesis of this acute phase protein.
Laxative online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8339522&dopt=Abstract lecithin
J Colloid Interface Sci. 1997 Jul 15;191(2):341-8.
Addition of (Tri-)Block Copolymers to Phospholipid Vesicles: A Study of the Molecular Morphology and Structure by Using Hydrophobic Dye Molecules as Bilayer Probes
Kostarelos K, Luckham PF, Tadros TF.
Formulation Section, Jealott's Hill Research Station, Zeneca Agrochemicals, Bracknell, Berkshire, RG12 6EY, United Kingdom
A dispersion of soybean lecithin in water leads to the formation of multilamellar vesicles (MLVs), which on sonication break down into small unilamellar vesicles of approximately 50 nm in diameter. The addition of polymeric molecules in the liposomal system is thought to provide the liposomes with a steric barrier. The molecules used were (tri-) block copolymers (Synperonics) containing a central hydrophobic part (polypropylene oxide) and two hydrophilic chains (polyethylene oxide). The aim of this work was to study whether it was possible to anchor deep inside the lipid bilayer the copolymer hydrophobic block. The exact localization of the copolymer molecules was investigated using a multiprobe technique. The full spectra of two hydrophobic dyes, namely Nile red (NIL) and Pinacyanol chloride (PCYN), were compared while solubilized inside the liposome bilayer. The sensitivity of their spectral characteristics to polarity and self-aggregation produced a monitor of the bilayer microenvironment. The more hydrophobic NIL proved an accurate polarity sensor of the bilayer microenvironment and the formation of PCYN dimers and nonabsorbing aggregates can be directly related to the local (bilayer) concentration of the dye and the volume available to the solubilized dye molecules. Shifts of the maximum absorbance (lambdamax) for both dyes showed that the bilayer environment was becoming more apolar with increasing copolymer concentration. The absorbance peak of PCYN due to dimer/aggregate formation increased at moderate copolymer concentrations, indicating that the polymer is incorporated inside the lipid bilayer.
Laxative online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9268516&dopt=Abstract lecithin [PubMed
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