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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Pharmaceutical research 12 (1995), S. 1614-1617 
    ISSN: 1573-904X
    Keywords: pKa ; stratum corneum ; fatty acid ; ionization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The apparent pKa of the fatty acids within hydrated (30 % w/w) model human stratum corneum (SC) lipid mixtures should be measured. Methods. The degree of ionisation of the fatty acids was calculated as a function of pH using Fourier transform infra-red spectroscopy. The relative intensity of the stretching bands of the unionized and ionized carboxylic groups was determined and fitted to the relevant expression for ionic equilibrium of a monoprotic acid. The pKa was then calculated for increasing proportion of unsaturated fatty acid in the lipid mixture. Results. Values for pKa in the range 6.2-7.3 were found, increasing with greater proportion of oleic acid. These are some 1.5-3 pH units higher than the pKas of fatty acids in molecular solution. Conclusions. As there exists a pH-gradient across the SC, the degree of ionisation will also vary. In the innermost SC layers, a pH of 7 will produce 90% ionization of the fatty acids and head-group repulsion will be great. At the SC surface, the pH of 5 will cause almost minimal head-group repulsion, tending to increase crystallinity and promote a bilayer structure.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Pharmaceutical research 17 (2000), S. 863-870 
    ISSN: 1573-904X
    Keywords: protein ; spray-dry ; surfactant ; surface-composition ; ESCA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To characterize via electron spectroscopy for chemical analysis(ESCA) the surface of spray-dried particles of trehalose plus aprotein (bovine serum albumin). Additionally, to show how and whythe addition of a surfactant reduces protein adsorption, and by thismechanism could reduce protein instability during spray-drying. Methods. Aqueous solutions of trehalose plus bovine serum albumin(bSA) were spray-dried with increasing concentrations of surfactant.The surface composition of the dried particles was examined usingESCA. Results.The presence of bSA, trehalose, and surfactant could bedetected quantitatively in the particle surface. In the absence of surfactantthe bSA had a large surface excess concentration (determined viaits N atoms). Increasing concentration of polysorbate 80 reduced thesurface excess of bSA in a concentration-dependent manner. At highpolysorbate 80 concentration (5 mg/ml) the bSA could no longer bedetected in solid surface. Using sodium dodecyl sulfate it was shownthat the reduction in surface concentration of the protein is accompaniedby a simultaneous increase in surface concentration of the surfactant.Neither surfactant fully covers the surface at the point of completeprotein exclusion. Conclusions. ESCA provides a direct, quantitative measure of thesurface composition of spray-dried trehalose/protein/surfactant particles.Surfactant reduces protein adsorption at the water/air-interface.This appears to be a result of complex formation with the surfactantwithin the bulk spray solution.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Pharmaceutical research 13 (1996), S. 421-426 
    ISSN: 1573-904X
    Keywords: stratum corneum ; barrier function ; diffusion equation ; non steady-state model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The diffusion equation should be solved for the non-steady-state problem of drug diffusion within a two-dimensional, biphasic stratum corneum membrane having homogeneous lipid and corneocyte phases. Methods. A numerical method was developed for a brick-and-mortar SC-geometry, enabling an explicit solution for time-dependent drug concentration within both phases. The lag time and permeability were calculated. Results. It is shown how the barrier property of this model membrane depends on relative phase permeability, corneocyte alignment, and corneocyte-lipid partition coefficient. Additionally, the time-dependent drug concentration profiles within the membrane can be observed during the lag and steady-state phases. Conclusions. The model SC-membrane predicts, from purely morphological principles, lag times and permeabilities that are in good agreement with experimental values. The long lag times and very small permeabilities reported for human SC can only be predicted for a highly-staggered corneocyte geometry and corneocytes that are 1000 times less permeable than the lipid phase. Although the former conclusion is reasonable, the latter is questionable. The elongated, flattened corneocyte shape renders lag time and permeability insensitive to large changes in their alignment within the SC. Corneocyte/lipid partitioning is found to be fundamentally different to SC/donor partitioning, since increasing drug lipophilicity always reduces both lag time and permeability.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Pharmaceutical research 3 (1986), S. 356-359 
    ISSN: 1573-904X
    Keywords: excised skin ; preparation ; dimensions ; morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The morphology and layer thicknesses of excised human and hairless mouse skin have been examined. Excised tissues were prepared either by heating at 60°C or by incubation in an ethylenediamine-tetracetic acid (EDTA) solution. Either process yielded spearated sheets of stratum corneum plus attached viable epidermis (SCE), the thicknesses of which were determined microscopically. These measurements indicated that initial skin separation occurred at the dermal/epidermal junction for both separation processes. The two techniques produced SCE sections showing consistent differences in thickness of the attached viable epidermis layer. This effect depended upon the presence or absence of epidermal invaginations. In the former case, EDTA-separated tissue gave narrower viable epidermis of more uniform thickness than that seen with heat-separated tissue. In the latter case, both techniques produced SCE having viable epidermis layers of similar thickness.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Bioconjugate chemistry 2 (1991), S. 367-374 
    ISSN: 1520-4812
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Abacus 25 (1989), S. 0 
    ISSN: 1467-6281
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Economics
    Notes: The copy of Luca Pacioli's Summa (1494) now owned by the University of Edinburgh, Scotland, exhibits at the end fifty-nine pages of manuscript additions, dating from the late fifteenth and early sixteenth centuries. There is evidence that this material was written in the main by Filippo Calandri, who published the first printed textbook of arithmetic in Florence in 1491/2. The author has deciphered most of the MS from photocopies.The material has no reference to bookkeeping or accounting, but is a curious and interesting product of the Renaissance Italian mind. Much of it appears to be notes for a book on mensuration, probably by Calandri, and incorporating some matter from his Arithmetica. The MS also includes many astrological calculations, and a series of Latin aphorisms with a prologue, besides (in another hand) a few magic charms or spells.The MS material is described and analysed, and the relation of its parts to one another, to Calandri and to Pacioli, is explored.
    Type of Medium: Electronic Resource
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  • 7
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    Unknown
    Nature Publishing Group (NPG)
    Publication Date: 2014-10-25
    Description: Nanobodies (Nbs) or single-domain antibodies are among the smallest and most stable binder scaffolds known. In vitro display is a powerful antibody discovery technique used worldwide. We describe the first adaptation of in vitro mRNA/cDNA display for the rapid, automatable discovery of Nbs against desired targets, and use it to discover the first ever reported nanobody against the human full-length glucose transporter, GLUT-1. We envision our streamlined method as a bench-top platform technology, in combination with various molecular evolution techniques, for expedited Nb discovery. Scientific Reports 4 doi: 10.1038/srep06760
    Electronic ISSN: 2045-2322
    Topics: Natural Sciences in General
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  • 8
    facet.materialart.
    Unknown
    Nature Publishing Group (NPG)
    Publication Date: 2015-04-24
    Description: We have developed a system for the rapid fabrication of low cost 3D devices and systems in the laboratory with micro-scale features yet cm-scale objects. Our system is inspired by maskless lithography, where a digital micromirror device (DMD) is used to project patterns with resolution up to 10 µm onto a layer of photoresist. Large area objects can be fabricated by stitching projected images over a 5cm2 area. The addition of a z-stage allows multiple layers to be stacked to create 3D objects, removing the need for any developing or etching steps but at the same time leading to true 3D devices which are robust, configurable and scalable. We demonstrate the applications of the system by printing a range of micro-scale objects as well as a fully functioning microfluidic droplet device and test its integrity by pumping dye through the channels. Scientific Reports 5 doi: 10.1038/srep09875
    Electronic ISSN: 2045-2322
    Topics: Natural Sciences in General
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  • 9
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    Unknown
    Nature Publishing Group (NPG)
    Publication Date: 2014-09-20
    Description: Article Voltage-gated sodium (Na V ) channels initiate action potentials in excitable cells and mutations at Na V loci are responsible for several human diseases. Here, Wang et al . provide novel structural insights into the regulation of Na V channel activity by calcium-bound calmodulin. Nature Communications doi: 10.1038/ncomms5896 Authors: Chaojian Wang, Ben C. Chung, Haidun Yan, Hong-Gang Wang, Seok-Yong Lee, Geoffrey S. Pitt
    Electronic ISSN: 2041-1723
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General , Physics
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