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  • transdermal delivery  (2)
  • Key words Stromboli  (1)
  • hepatocyte
  • 1
    Electronic Resource
    Electronic Resource
    Sub-volcanic crystallization at Stromboli (Aeolian Islands, southern Italy) preceding the Sciara del Fuoco sector collapse: evidence from monzonite lithic suite (1997)
    Springer
    Bulletin of volcanology 59 (1997), S. 10-20 
    Details
    ISSN: 1432-0819
    Keywords: Key words Stromboli ; Neostromboli ; Orthocumulates ; Monzonites ; Magma chamber processes ; Geothermobarometry ; Flank collapse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  We describe texture, mineralogy and whole-rock composition of cognate monzonite sub-volcanic clasts within debris flow deposits related to the 5000 years catastrophic phreatomagmatic eruption probably linked to the Sciara del Fuoco sector collapse. The debris flows are at the top of accretionary lapilli-rich ash deposits overlying potassic (KS, shoshonites) lavas of the Neostromboli period. The monzonites are inferred to be crystallized in situ, at low P, at the side walls and/or roof margins of a shallow magma chamber and to be cogenetic with the KS Neostromboli extrusives. They can be considered "ideal orthocumulates" since they approximately retain a bulk liquid composition and possibly represent "slowly cooled equivalents" of their KS shoshonite host rock. The "closure temperature" of final solidification of the monzonite lithic suite was estimated through ternary-feldspar geothermobarometry, plagioclase–K-feldspar and K-feldspar–biotite equilibria and is in the range of 750–790  °C with a maximum –logfO2 around 15.1–15.3. The estimated pressure of crystallization is 〈0.5 kbar. Potassic lavas and dikes, previously emplaced during the Neostromboli period, also resemble the monzonites in both major trace elements and mineral chemistry. The cogenetic relationship between KS Neostromboli extrusives and the monzonite host-rock magma from which the sub-volcanic clasts were derived is clear evidence that a shallow magma chamber existed between the caldera collapse of the Vancori period and the Sciara del Fuoco sector collapse (i.e. between 13 000 and 5000 years). The monzonite clasts were derived from crystallization at very shallow depth (ca. 1 km) and strongly support the hypothesis of violent decompression of the shallow magmatic plumbing system during the Sciara del Fuoco sector collapse. Climax of the regressive landslide event, with maximum disruption of the chamber walls, took place during emplacement of the debris flows, i.e. during the late stage of the Neostromboli phreatomagmatic eruption.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004450050171
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  • 2
    Electronic Resource
    Electronic Resource
    Membrane modifications in the course of hepatocyte isolation (1990)
    Springer
    Cytotechnology 4 (1990), S. 251-259 
    Details
    ISSN: 1573-0778
    Keywords: hepatocyte ; isolation ; membrane junctions ; electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A transmission E/M, scanning E/M and freeze fracture ultrastructural study has been performed on the rat hepatocyte in the course of isolation from the liver parenchyma. The cell submicroscopic aspect indicates a good morpho-functional preservation from the liver perfusion to the final stages of cell isolation. The freeze fracture membrane analysis evidentiates the constant presence of gap junctions and tight junctions, characterized by particular structural alterations, probably due to progressive functional uncoupling. The persistence of these cell differentiations until complete cell isolation may be considered a further morphological expression of the maintenance of the differentiated stage of the hepatocyte. Fragments of membranes from adjacent cells, still adherent to isolated hepatocyte surfaces, can also be occasionally detected by freeze-fracture techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00563785
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  • 3
    Electronic Resource
    Electronic Resource
    Iontophoresis Enhances the Transport of Acyclovir Through Nude Mouse Skin by Electrorepulsion and Electroosmosis (1995)
    Springer
    Pharmaceutical research 12 (1995), S. 1623-1627 
    Details
    ISSN: 1573-904X
    Keywords: iontophoresis ; acyclovir ; electroosmosis ; electrorepulsion ; transdermal delivery ; nude mouse skin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. Iontophoresis was employed for enhancing the transdermal delivery of acyclovir through nude mouse skin in vitro, with the aim of understanding the mechanisms responsible for drug transport, in order to properly set the conditions of therapeutical application. Methods. Experiments were done in horizontal diffusion cells, using as donor a saturated solution of acyclovir at two different pH values (3.0 and 7.4). Different electrical conditions (current density and polarity) were employed. Results. At pH 3.0, acyclovir anodal transport was due to electrorepulsion, since acyclovir was 20% in the protonated form. In acyclovir anodal iontophoresis at pH 7.4 the main mechanism involved was electroosmosis, since the drug was substantially unionized and the negative charge of the skin at this pH caused the electroosmotic flow to be from anode to cathode. In the case of cathodal iontophoresis at pH 3.0, acyclovir transport was enhanced approx. seven times, due to the presence of an electroosmotic contribution caused by the reversal of the charge of the skin. At pH 7.4 during cathodal iontophoresis acyclovir transport was not enhanced because the electroosmotic flow was in the opposite direction, compared to drug electric transport, i.e. anode to cathode. The increased skin permeability caused by current application was demonstrated to be less important than electrorepulsion and electroosmosis. Conclusions. Anodal iontophoresis shows potential applicability for enhancing acyclovir transport to the skin, considering that both electric transport and electroosmosis can be used by appropriately setting the pH of the donor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016284815501
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  • 4
    Electronic Resource
    Electronic Resource
    Drug Reservoir Composition and Transport of Salmon Calcitonin in Transdermal Iontophoresis (1997)
    Springer
    Pharmaceutical research 14 (1997), S. 63-66 
    Details
    ISSN: 1573-904X
    Keywords: iontophoresis ; transdermal delivery ; calcitonin ; reservoir ; peptide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The aim of the work was to study iontophoretic transdermal administration of salmon calcitonin (sCt) in rabbits, with particular attention to drug reservoir composition. A dry sCt disc, to be dissolved on the application site, was used for preparing the reservoir for transdermal iontophoresis. As a reference drug reservoir, a pad wetted with drug solution was used. Methods. Experiments were done in rabbits depositing 100 IU of salmon calcitonin on skin and applying anodal iontophoresis. Serum calcium concentration was measured during iontophoresis, passive diffusion and after i.v. administration. Parameters such as pH value and reservoir type were examined. Results. Transdermal iontophoresis of sCt elicited a decrease in the serum calcium level, whereas, in the absence of electric current, no significant fall was measured. Using the reservoir prepared from drug solution, anodal iontophoresis at pH 4.2 was more effective than at pH 7.4, probably due to higher sCt net positive charge. Using the reservoir prepared from dry disc, similar kinetics and extent of drug effect were observed at both pH values. The reservoir prepared from solid drug deposit concentrated sCt next to the skin. Conclusions. Anodal iontophoresis for transdermal calcitonin administration shows therapeutical applicability. The type of reservoir is an important parameter affecting sCt transdermal iontophoresis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1012055401038
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