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  • 1995-1999  (3)
  • Adenosine AZA receptor  (1)
  • Interaction mechanism  (1)
  • Key words Cervical spine • Traumatic atlantoaxial instability • Transarticular screw Fixation C1/C2 • Minimally invasive technique  (1)
  • 1
    ISSN: 1433-0431
    Keywords: Key words Cervical spine • Traumatic atlantoaxial instability • Transarticular screw Fixation C1/C2 • Minimally invasive technique ; Schlüsselwörter Halswirbelsäule • Atlantoaxiale Instabilität • Transartikuläre Verschraubung C1/C2 • Minimal-invasive Technik
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die Spondylodese C1/C2 mit dorsaler transartikulärer Verschraubung stellt bei traumatischen atlantoaxialen Instabilitäten das Verfahren der Wahl dar. Beim offenem Vorgehen müssen die empfindlichen Weichteile des Nackens bis zum 7. Halswirbel freigelegt werden, um die Bohrmaschine weit genug absenken und die Schrauben steil genug einbringen zu können. Zur Verringerung des Weichteiltraumas wurden deshalb von verschiedenen Autoren eine perkutane Technik angegeben. Wir analysierten die von uns mit beiden Verfahren behandelten Patienten der Jahre 1995–1998, um zu prüfen, ob die perkutane Technik Vorteile bietet. 30 Patienten mit traumatischer sagittaler atlantoaxialer Instabilität wurden von dorsal transartikulär verschraubt. 19mal verwendeten wir die perkutane Technik mit Hilfe des Spezialinstrumentariums von McGuire und Harkey. Anhand der postoperativen Röntgenaufnahmen wurde in der Sagittalebene der Winkel zwischen Axisgrundplatte und Schrauben gemessen; 6–24 Monate nach dem Unfall wurden 26 Patienten nachuntersucht, 4 waren zum Zeitpunkt der Nachuntersuchung verstorben. Der Schraubenwinkel war bei der perkutanen Technik größer als beim offenen Vorgehen. Die Mittelwerte (M) beider Gruppen unterschieden sich um 10 ° (perkutan: M = 73,9 °, offen: M = 63,9 °, t-Test: p = 0,001). Die Operationszeit bei perkutaner Technik war im Schnitt 35 min kürzer (93 zu 128 min, t-Test: p = 0,05). Jeweils 2 Patienten beider Gruppen verstarben aufgrund von Begleitverletzungen oder maligner Erkrankungen. Bei der Nachuntersuchung von 26 Patienten waren alle Spondylodesen radiologisch durchbaut. Die Schraubenlage hatte sich nur in einem Fall mit offener Technik geringfügig geändert. Die Beweglichkeit der HWS war in beiden Gruppen gleich stark eingeschränkt. Die subjektive Beurteilung bezüglich Schmerzfreiheit und Funktion mit Hilfe einer Visualanalogskala und eines speziellen Erfassungsbogens ergab Vorteile zugunsten der Gruppe mit perkutaner Technik (z. B.: Schmerzfreiheit: 43 (perkutan) zu 39 (offen) Punkte, t-Test: p = 0,05). Vor der Verletzung hatten die Patienten beider Gruppen vergleichbare Scores aufgewiesen. Die weichteilschonende, perkutane Technik der transartikulären Verschraubung C1/C2 unter Verwendung eines Spezialinstrumentariums erlaubt eine bessere und einfachere Schraubenplazierung. Dies führt auch zu einer kürzeren Operationszeit und – vermutlich durch geringere Schädigung der Nackenmuskulatur – zu besseren subjektiven Ergebnissen. Die Methode besitzt besonders große Vorteile bei solchen Patienten, die nur eine temporäre Stabilisierung des C1/C2-Komplexes ohne Fusion benötigen.
    Notes: Summary For posttraumatic atlantoaxial instabilities posterior transarticular screw fixation according to Magerl represents the treatment of choice. In order to be able to insert the screws steep enough the soft tissues of the neck have to be dissected down to C7. Several authors therefore described a percutaneous technique. We analysed 30 patients with a sagittal atlantoaxial instability treated with one of both methods between the years 1995 and 1998 to detect amny differences of either technique. In 19 cases we used a modified percutaneous technique with special instruments as has been published by McGuire and Harkey. On lateral plain films the angle between the screws and the lower endplate of C2 was measured. 6 to 24 months after the accident 26 patients could be seen clinically and controlled radiologically, 4 patients had died in the meanwhile. The angle of the screws were significantly different with 10 degrees (percutaneous group 73,9 degrees, open group 63,9 degrees, p = 0,001). Time needed for the operativ procedure averaged 35 minutes shorter with the canulated technique (93 to 128 minutes, p = 0.05). All posterior fusions had healed radiologically. Active motion of the c-spine was restricted in both groups equally. We checked subjective criteria concerning pain and function with a visual analog scale and a special score. With these instruments advantages for the percutaneous procedure could be found (freedom of pain 43 points (percutaneous) versus 39 points (open), p = 0.05). We conclude that the soft tissue preserving percutaneous technique of screw application for C1/C2 posterior fusion allows for a better and easier placement of screws. It also leads to a shorter operating time and better subjective results. The method offers particularly advantages in cases where only a temporary satbilization of the C1/C2 complex without a regular fusion is needed.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1438-2199
    Keywords: Rat striatum ; Medium spiny neuron ; Adenosine AZA receptor ; NMDA receptor channel ; Whole-cell patch clamp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Whole-cell patch clamp experiments were carried out in rat striatal brain slices. In a subset of striatal neurons (70–80%), NMDA-induced inward currents were inhibited by the adenosine AZA receptor selective agonist CGS 21680. The non-selective adenosine receptor antagonist 8-(p-sulphophenyl)-theophylline and the AZA receptor selective antagonist 8-(3chlorostyryl) caffeine abolished the inhibitory action of CGS 21680. Intracellular GDP-β-S, which is known to prevent G protein-mediated reactions, also eliminated the effect of CGS 21680. Extracellular dibutyryl cAMP, a membrane permeable analogue of cAMP, and intracellular Sp-cAMPS, an activator of cAMP-dependent protein kinases (PKA), both abolished the CGS 21680-induced inhibition. By contrast, Rp-cAMPS and PKI 14–24 amide, two inhibitors of PKA had no effect. Intracellular U-73122 (a phospholipase C inhibitor) and heparin (an inositoltriphosphate antagonist) prevented the effect of CGS 21680. Finally, a more efficient buffering of intracellular Ca2+ by a substitution of EGTA (11 mM) by BAPTA (5.5 mM) acted like U-73122 or heparin. Hence, AZA receptors appear to negatively modulate NMDA receptor channel conductance via the phospholipase C/inositoltriphosphate/Ca2+ pathway rather than the adenylate cyclase/PKA pathway.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Molecular modelling ; Molecular mechanics calculations ; Permethylated α-, β- and γ-cyclodextrins ; Interaction mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The capillary gas chromatographic retention behavior of α-pinene and tricyclene has been investigated on stationary phases of different polarities. On all but one of the columns employed, tricyclene eluted before α-pinene; only permethylated β-cyclodextrins dissolved in moderately polar polisiloxanes gave a reversed elution order. The intermolecular interactions which caused the unexpected retention behavior were investigated in detail, applying methods of computer simulation. To achieve this, we have developed a calculation algorithm on the basis of molecular mechanical optimizations and programmed it in a macro. This makes it possible to systematically investigate a given configuration space in which all the possible interactions can take place. It was shown that permethylated β-cyclodextrin as host molecule for both guest molecules offers an optimum cavity size. As a result the number of energetically favorable contacts between host and guest molecules as well as the strength of the interactions in this stationary phase were larger. As a consequence the elution order, normally only influenced by the vapor pressure of the compounds at a given temperature, was changed. Nonspecific interactions played an especially important role for these kinds of substances.
    Type of Medium: Electronic Resource
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