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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Analytical chemistry 67 (1995), S. 405-410 
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Der Orthopäde 28 (1999), S. 500-508 
    ISSN: 1433-0431
    Keywords: Key words Osteochondral lesion • Osteochondrosis dissecans • Talus • Diagnostic • Therapy ; Schlüsselwörter Osteochondrale Läsionen • Osteochondrosis dissecans • Talus • Diagnostik • Therapie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Osteochondrale Defekte des Talus werden häufig nicht oder verspätet diagnostiziert. Sie stehen meist im Zusammenhang mit traumatischen Läsionen des oberen Sprunggelenkes (OSG), wobei Distorsionstraumen den Hauptanteil ausmachen. Die als degenerative Veränderung klassifizierte Osteochondrosis dissecans tali weist in den meisten Fällen ebenfalls eine ursprünglich traumatische Genese auf. Allgemein hat sich die Einteilung der osteochondralen Läsionen in vier Stadien nach Berndt und Harty durchgesetzt. Diese können durch verschiedene Diagnoseverfahren differenziert werden, und gelten als richtungsweisend hinsichtlich Therapie und Prognose. Grundsätzlich reicht für die Diagnostik die konventionelle Röntgenaufnahme in 2 Ebenen bei entsprechender Fußstellung aus. Obwohl die Szintigraphie und Computertomographie (CT) bei bestimmten Fragestellungen ihre Berechtigung haben, weist das MRT die höchste diagnostische Aussagekraft auf. Als standardisiertes therapeutisches Verfahren gilt bei gering ausgeprägten Defekten (Stadium I und II) die konservative Therapie. Die chirurgische Intervention kommt bei ausgeprägteren Läsionen (Stadium III/IV) zum Einsatz. Neben dem offenen chirurgischen Vorgehen gewinnt die Arthroskopie zunehmend an Bedeutung mit positiven Langzeitresultaten in über 60 % der Patienten. Diese weist neben einer Reihe von Vorteilen jedoch auch Grenzen gegenüber der Arthrotomie auf. Die Effizienz neuer Therapiemethoden wie Knochen-Knorpel-Transplantation und Chondrozytentransplantation gegenüber den herkömmlichen Débridement mit Microfractures sowie der Fragmentrefixation muß in Langzeitstudien noch belegt werden. Die Ergebnisse sind abhängig vom Stadium und der Lokalisation des osteochondralen Defekts. Im fortgeschrittenen Stadium III/IV sind chirurgische Maßnahmen wie Débridement, Entfernung der Dissekate mit Mikrofragmentierung des Dissekatbettes bzw. Refixation indiziert, da hier konservative Therapieversuche eindeutig zu schlechteren Ergebnissen führten. Insgesamt konnten überwiegend gute und sehr gute Ergebnisse mit Schmerzfreiheit und Vollbelastung erzielt werden.
    Notes: Summary Osteochondral lesions of the talus are often not or delayed diagnosticated. They mostly are related to traumatic lesions of the upper ankle joint, where by traumatic distorsion are most common among. The degenerative change classified as osteochondrosis dissecans tali shows in the most cases also an originally traumatic generic. The classification by osteochondrosis dissecans tali in four stages by Berndt and Harty is nowadays accepted. These can be distinguished by means of several diagnostic methods. They are regarded as state-of-the-art of therapy and prognosis. Basically for diagnostic purposis the conventional X-ray in two planes with the right feet-allignement is sufficient. Despite the fact, that Szintigraphy and Computertomography for particullar questions are the right tools, the MRI gives the highest amount of information. In the case of low levels of defects (Stage I and II) the conservative therapy is appropriate. In more seriouse cases (Stage III and IV) the surgical intervention has to be used. Beside the open surgical approach the arthroscopy has a growing importancy. In 60 % of cases good long term results can be achieved. Beside some advantage there are some limits compared to the arthrotomy. The efficiency of new therapeutic methods like bone-cartilage-transplantation and chondrocyte-transplantation compared to the conventional wound toilet, microfractures and fragmentrefixation has to be proved by long term studies. The results depend on the stage and the localisation of the osteochondral lesion. In the developed stages III and IV surgical actions as wound toilet, removement of dissecate with microfragmentation respectivally refixation are indicated, since conservative therapy methods lead undoubtely to worse results. Generally mostly good and very good results connected with painless and weight bearing could be achieved.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-6830
    Keywords: ACh, acetylcholine ; nAChR, nicotinic acetylcholine receptor ; EGTA, [ethylenebis(oxyethylenenitrilo)]tetraacetic acid ; HEPES, N-(2-hydroxyethyl)piperazine-N′-(2-ethanesulfonic acid) ; OR2, oocyte Ringer's solution ; MOR2, modified oocyte Ringer's solution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. Chronic administration of nicotine up-regulates mammalian neuronal nicotinic acetylcholine receptors (nAChRs). A key hypothesis that explains up-regulation assumes that nicotine induces desensitization of receptor function. This is correlated with behaviorally expressed tolerance to the drug. 2. The present experiments were conducted to: (a) obtain information on the nicotine-induced desensitization of neuronal nAChR function, a less understood phenomenon as compared to that of the muscle and electric fish receptor counterparts; (b) test the hypothesis that different receptor subunit combinations exhibit distinct desensitization patterns. 3.Xenopus laevis oocytes were injected with mRNAs encoding rat receptor subunitsα2,α3, orα4 in pairwise combination with theβ2 subunit. The responses to various concentrations of acetylcholine (ACh) or nicotine were analyzed by the two electrode voltage clamp technique. 4. Concentration-effect curves showed that nicotine was more potent than ACh for all the receptor subunit combinations tested. Only theα4β2 combination exhibited a depression of the maximum effect at concentrations higher than 20µM nicotine. 5. After a single nicotine pulse, receptor desensitization (calculated as a single exponential decay) was significantly slower forα4β2 than for eitherα3β2 orα2β2. 6. Concentrations of nicotine that attained a near maximum effect were applied, washed, and re-applied in four minute cycles. The responses were calculated as percentages of the current evoked by the initial application. Following 16 minutes of this protocol, theα4β2 combination showed a greater reduction of the original response as compared to theα2β2 andα3β2 subunit combinations. Taking points 5 and 6 together, these experiments suggest that theα4β2 receptor subtype desensitizes at a slower rate and remains longer in the desensitized state. 7. Becauseα4β2 is the main receptor subunit combination within the brain and is up-regulated by nicotine, our data may be important for understanding the molecular basis of tolerance to this drug.
    Type of Medium: Electronic Resource
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