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  • 1
    Electronic Resource
    Electronic Resource
    Prolonged release of drug from triacetyl-β-CyD complex for oral and rectal administration (1996)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 25 (1996), S. 181-184 
    Details
    ISSN: 1573-1111
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Triacetyl-β-cyclodextrin (TA-β-CyD), a hydrophobic cyclodextrin derivative, that is insoluble in water, was used to form a complex with flufenamic acid (FA). FA-TA-β-CyD complex formation was demonstrated by differential scanning calorimetry and powder X-ray diffractometry. The release rate of FA from the FA-TA-β-CyD complexes in phosphate buffer pH 6.8 was significantly retarded compared to that of FA from the FA and glucose mixture. When the FA-TA-β-CyD complexes were administered directly into the intraduodenal lumen, the plasma concentration of FA remained at a plateau level (10-18 μg/ml) for 6–8 h. An increased mean residence time of FA following FA-TA-β-CyD complexes administration was observed. These results indicate that TA-β-CyD may serve as a hydrophobic carrier in prolonged-release preparations of FA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01041565
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  • 2
    Electronic Resource
    Electronic Resource
    Activation and inhibition of lipoprotein lipase in mixed monolayers of medium or long chain-triglycerides and phospholipids (1997)
    Springer
    Colloid & polymer science 275 (1997), S. 60-66 
    Details
    ISSN: 1435-1536
    Keywords: Key words Lipoprotein lipase ; inhibition ; phosphatidylcholine ; sphingomyelin ; triglyceride ; monolayer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  We evaluated the activation and inhibition effects of phosphatidylcholine (PC) and sphingomyelin (SM) on lipoprotein lipase (LPL) for medium or long chain-triglycerides (TG) in monolayers at the air/water interface. Monolayers of medium chain-TG, being in an expanded state at a surface pressure of 15 mN/m, showed low susceptibility to LPL in the subphase. Adding 50 mole% of PC or SM into these monolayers reduced the partial molecular area of the TG and enhanced the LPL activity. Monolayers of long chain-TG, being in a condensed state, showed high susceptibility of LPL either with or without PC. SM added to the long chain-TG monolayers, however, inhibited the LPL action. We investigated the interaction between TG and phospholipid on the basis of the collapse pressure-measurements of mixed monolayers. For medium chain-TG monolayers, PC and SM gave similar collapse pressure-composition profiles. Contrary to this, SM gave a markedly higher collapse pressure of long chain-TG than PC: SM stabilized the monolayer state of long chain-TG. These results suggested that I) orientation of the acyl chains of TG molecule in a monolayer is crucial for the LPL activity, and that II) strong interaction between SM and long chain-TG retards the substrate-transfer from the mixed monolayer to the catalytic pocket of LPL.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050052
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  • 3
    Electronic Resource
    Electronic Resource
    Product-retardation and -activation of catalytic hydrolysis by phospholipase D in small unilamellar vesicles of egg yolk phosphatidylcholine (1997)
    Springer
    Colloid & polymer science 275 (1997), S. 627-633 
    Details
    ISSN: 1435-1536
    Keywords: Key words Phospholipase D ; egg yolk phosphatidylcholine ; small unilamellar vesicles ; product-retardation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  We evaluated the hydrolysis of egg yolk phosphatidylcholine (PC) by phospholipase D from Streptomyces chromofuscus (PLD) in small unilamellar vesicles (SUV) in presence of 50 μM Ca2+. After initial choline production (hydrolysis of 1.5% of the PC at the outer leaflets of the vesicle bilayers), the hydrolysis was reduced to 5% of the initial velocity. The kinetic behavior in SUV of premixed PC and a low percentage of the hydrolysis product, phosphatidic acid (PA), was similar to that of PC SUV. The reduced velocity disappeared when the membrane structure was disintegrated by means of a nonionic surfactant. In the retardation phase, the partially hydrolyzed vesicles (postsubstrates) had much higher affinity for PLD than fresh PC SUV. These results indicated that small clusters of the product, PA, at the vesicle surface were responsible for the reduced velocity of hydrolysis. The initial velocity increased in a biphasic manner with the substrate concentration. At a PC concentration range up to 4 mM, the experimental data fit Michaelis–Menten kinetics. At concentrations above 6 mM, the velocity again markedly increased. Negatively charged mixed vesicles of PC and PA did not have such kinetics. Furthermore, adding PC SUV to the postsubstrates, where the fraction of free PLD was less than 0.05, induced steep choline production. These results showed that PLD bound to vesicles had higher activity than free PLD. We speculated that PLD bound to vesicles collided with and was directly transferred to PC SUV when the fraction of free PLD in aqueous medium was very small.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050128
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  • 4
    Electronic Resource
    Electronic Resource
    Generation and electronic properties of lanthanide–cyclooctatetraene organometallic clusters in gas phase (1999)
    Springer
    The European physical journal 9 (1999), S. 283-287 
    Details
    ISSN: 1434-6079
    Keywords: PACS: 36.40.-c Atomic and molecular clusters – 36.40.Mr Spectroscopy and geometrical structure of clusters – 61.46.+w Clusters, nanoparticles, and nanocrystalline materials – 71.24.+q Electronic structure of clusters and nanoparticles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract. Organometallic clusters of lanthanide (Ln = Nd, Er, Eu, and Yb) and 1,3,5,7-cyclooctatetraene (C8H8) were produced by a combination of laser vaporization and molecular beam methods. In the mass spectra of [Ln n (C8H8) m ], compositions of m=n+1 were magic numbers. From mass spectrometry, photoionization spectroscopy, and photoelectron spectroscopy, we have concluded that these magic-numbered clusters take multiple-decker sandwich structures in which Ln atoms and C8H8 molecules are alternatedly piled up. These sandwich clusters are formed through ionic bonds composed of multiply charged cations [Ln k+  (k=2 and 3)] and multiply charged anions [C8H8 h-  (h=1, 1.5, and 2)].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00010926
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