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  • 1
    ISSN: 1573-904X
    Keywords: liposome ; phosphatidylserine ; Peyer's patches ; uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Uptake of the nonabsorbable marker 6-carboxyfluorescein was investigated both free and encapsulated in liposomes as a function of their surface charge and hydrodynamic diameter in rat Peyer's patch and nonpatch tissue. Significant uptake of the marker occurred only when encapsulated in liposomes consisting of at least 25 mol% phosphatidylserine and was highest in Peyer's patches. 6-Carboxyfluorescein encapsulated in liposomes equal to or greater than 374 nm was preferentially taken up by Peyer's patches. There was a trend to higher uptake in lower intestinal segments. These findings were supported by fluorescence microscopic observations. Uptake by Peyer's patches was specific for negatively charged liposomes as judged from competition studies.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-904X
    Keywords: liposome ; oral administration ; Peyer's patch ; oral vaccine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract To evaluate the usefulness of liposomes as a carrier for the targeted delivery of antigens to gut-associated lymphoid tissue, liposomal stability and uptake by rat Peyer's patches were investigated. Liposomes composed of distearoylphosphatidylcholine, phosphatidylserine, and cholesterol (DSPC-liposome), or dipalmitoylphosphatidylcholine, phosphatidylserine, and cholesterol were stable in acidic solution (pH 2.0), diluted bile, and pancreatin solution. Following the oral administration of liposomes to rats, rhodamine B-PE incorporated in the lipid phase of DSPC-liposomes was preferentially taken up by Peyer's patches in the lower ileum. The uptake of rhodamine B-PE from DSPC-liposomes larger than 374 nm in mean diameter was high. Orally administered DSPC-liposomes of a large diameter thus appear to serve effectively as a vehicle for delivering antigens to Peyer's patches.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-904X
    Keywords: liposome ; macrophage ; phagocytosis ; Fc receptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The effects of liposomes on the phagocytic activity of mouse peritoneal macrophages were investigated using IgG-opsonized sheep red blood cells (SRBC). The highest ingestion index of opsonized SRBC via Fc receptors of macrophages from BALB/c mice was observed for macrophages harvested on day 4 following the intra-peritoneal injection of liposomes (2.27 µmol lipid/mouse). An increase in the ingestion index was observed irrespective of liposomal charge. Binding parameters of Fc receptors of macrophages from liposome- or saline-injected mice were determined using horseradish peroxidase-conjugated IgG, and an increase in the number of binding sites with the same binding constant was observed in macrophages from liposome-injected mice. The activation mechanism of mouse peritoneal macrophages by liposomes differed from that by lipopolysaccharides. Liposomes thus appear to contribute to the activation of immune response.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-904X
    Keywords: antisense oligonucleotide ; interleukin-10 ; antisense effect ; melting temperature ; secondary structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The two objectives of this study were to design potent phosphorothioate antisense oligonucleotides (AS-S-oligos) directed against the human interleukin-10 (IL-10) gene product and to reveal the DNA sequence which best activates antisense effects. Methods. The design of potent AS-S-oligo was performed by using melting temperature (Tm) value of a DNA/RNA hybrid calculated by the nearest neighbor method and a secondary structure of human IL-10 mRNA suggested by RNA folding algorithms. U937 cells were used to estimate the antisense effect of the AS-S-oligos. Results. Of the eight candidates selected as potent AS-S-oligos on the basis of having higher Tm values and favorable secondary structures of the IL-10 mRNA, AS-S-oligos directed against the translated (AS367-S-oligo) and 3′-untranslated (AS637-S-oligo) region of IL-10 mRNA showed the strongest inhibitory effects on IL-10 production and this inhibition was dose- and time-dependent. Reverse transcription-polymerase chain reaction (RT-PCR) revealed that the antisense effects of AS-S-oligos originated from a specific reduction of target IL-10 mRNA by hybridization with AS367- and AS637-S-oligos. In addition, these AS-S-oligos did not affect human tumor necrosis factor-∝ (TNF-∝) production in the cells stimulated by lipopolysaccharide (LPS). Strong positive correlations between the inhibitory effect of AS-S-oligos on the IL-10 production and not only Tm values calculated by nearest neighbor method but also Tm values determined by absorbance versus temperature profiles were demonstrated except for AS25-S-oligo and AS1249-S-oligo. Conclusions. These findings suggest AS367- and AS637-S-oligos powerfully inhibit IL-10 production in U937 cells via an antisense mechanism. In addition, it is suggested efficiency of AS-S-oligo directed against the sequence of the target gene product can be explained by these Tm values and the proposed secondary structures of the target gene product.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Pharmaceutical research 6 (1989), S. 362-366 
    ISSN: 1573-904X
    Keywords: aminoglycoside ; nephrotoxicity ; phospholipid ; liposome ; aggregation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Interactions of aminoglycosides with phospholipids were estimated by the increase in turbidity of liposomes consisting of various phospholipids. The turbidity of liposomes containing negatively charged phospholipids was increased by gentamicin, the highest increase in turbidity being observed for phosphatidylinositol-4,5-diphosphate-containing liposomes. The extent of turbidity was dependent on the concentration of acidic phospholipid in the liposomal membrane as well as the number of amino groups of the aminoglycosides. The release of glucose from glucose-entrapped liposomes depended on the concentration of gentamicin. The turbidity of liposomes containing lipids extracted from rat renal cortex was also increased by aminoglycosides depending on the number of amino groups. From electron microscopic observations, the increase in turbidity of liposome suspensions was caused by liposome fusion.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-904X
    Keywords: liposome ; targeting ; asialofetuin ; hepatocytes ; interferon-gamma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The selective delivery of human recombinant interferon (IFN)-γ to isolated rat hepatocytes was studied with asialofetuin (AF)-labeled liposomes. AF-liposomes containing buffer solution were initially prepared by the detergent removal method, and IFN-γ was subsequently encapsulated by the freeze-thawing method without loss of activity. Virtually no free [32P]IFN-γ was internalized into isolated rat hepatocytes, whereas AF-liposomes containing [32P]IFN-γ were taken up to a significant degree. Liposomal binding to the hepatocytes (estimated at 4°C) was one-fifth of the uptake (estimated at 37°C). Since the uptake was inhibited by the addition of free AF, AF-liposomes may be taken up by the action of galactose-binding protein on the hepatocytic cell surface. The liposome preparation method reported in this paper provides a useful means for the encapsulation of unstable macromolecules into AF-liposomes. AF-liposomes were found effectively to carry IFN-γ into hepatocytes in vitro.
    Type of Medium: Electronic Resource
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