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  • 1
    ISSN: 1432-1440
    Keywords: Coronary occlusion ; epicardial mapping ; infarction size ; fibrinolysis ; Streptokinase ; fibrinogen degradation products ; Coronarocclusion ; epicardiales EKG ; Infarktgröße ; Fibrinolyse ; Streptokinase ; Fibrinogen-Spaltprodukte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Bei 17 narkotisierten Hunden wurden mehrere Seitenäste des Ramus descendens der linken Kranzarterie unterbunden. Die ST-Segmentelevation im epikardial abgeleiteten EKG stieg dabei bis auf 22 mV nach 5 min und 19 mV nach 20 min an. Aortendruck, enddiastolischer Druck im linken Ventrikel, Herzfrequenz und die hämostasiologischen Parameter (Plasmathrombinzeit, Thrombinkoagulasezeit, Reptilasezeit, Plasmafibrinogen, Staphylokokken-Clumping-Test) änderten sich nicht. 20 min nach Beginn der Okklusion wurden die Gefäße geöffnet. Nachdem sich die St-Segmenthebung zurückgebildet hatte, wurde eine kontrollierte Fibrinolyse (Streptokinase 1,5 Mega I.E. in 30 min initial, Fortführung mit 0,75 Mega I.E./h) eingeleitet. Wenn die hämostasiologischen Parameter eine effektive Lyse anzeigten, wurden die gleichen Gefäße erneut unterbunden. Auch jetzt änderten sich die hämodynamischen Größen nicht wesentlich. Die ST-Segment-Elevation war jedoch signifikant um 50% geringer als nach einfacher Ligatur. Eine Kontrollgruppe, die nur das Lösungsmittel der Streptokinase erhielt, zeigte dagegen einen unveränderten Anstieg der ST-Streckenelevation. Die Wirkung der Streptokinase wird auf das Auftreten von Fibrinogen-Spaltprodukten und die Senkung des Fibrinogenspiegels zurückgeführt, die eine Verbesserung der Mikrozirkulation hervorrufen.
    Notes: Summary In 17 unaesthetized dogs several side branches of the left descending coronary artery were ligated. The ST-segment elevation in the epicardial ECG ascended to 22 mV after 5 min and to 19 mV after 20 min. Aortic pressure, left ventricular enddiastolic pressure, heart rate and hemostasiological parameters (thrombin-time, thrombin-coagulase-time, reptilase-time, plasma-fibrinogen, staphylococcal clumping test) did not change significantly. 20 min after the beginning of coronary occlusion, the vessels were reopened. When ST-segment elevation had disappeared, a controlled fibrinolytic therapy (Streptokinase 1.5 Mega I.E. in 30 min, later on 0.75 Mega I.E./h) was induced. When an effective fibrinolysis could be demonstrated by the hemostasiological parameters, the same vessels were occluded again. Now the hemodynamic parameters too did not change significantly, but the ST-segment elevation was significantly diminished for more than 50% compared with simple ligation. A control group, which only got the solvent of the streptokinase, showed the same ST-segment elevation. This effect, induced by streptokinase is ascribed to fibrinogen degradation products and a diminution in the amount of fibrinogen which cause an improvement of microcirculation.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 25 (1978), S. 59-68 
    ISSN: 1432-0827
    Keywords: Amorphous calcium phosphate ; Thermodynamics ; Apatite ; Octacalcium phosphate ; Tricalcium phosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary A thermodynamic analysis of the precipitation of amorphous calcium phosphate (ACP) and its transformation to crystalline apatite has been made. A nearly constant ion product, over a wide variety of conditions, was obtained for a tricalcium phosphate (TCP)-like phase suggesting that the molecular unit which governs the solubility of ACP may be similar in composition to TCP. The introduction of 10% acid phosphate into the formula for the TCP ion product improves the fit of experimental data and results in an invariant ion product. The stability of ACP in solution was found to be dependent upon its thermodynamic instability with respect to an octacalcium phosphate (OCP)-like phase. The dependence of the induction period for the amorphous to crystalline transformation upon the pH and the Ca/P ratio of the solution is best explained by the assumption that an OCP-like phase is initially nucleated on the surfaces of the ACP particles. The events that occur in the immediate post-transition period suggest the hydrolysis of this OCP-like material to an apatitic phase.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 25 (1978), S. 209-216 
    ISSN: 1432-0827
    Keywords: Thermodynamics ; Kinetics ; Apatite ; Octacalcium phosphate ; Tricalcium phosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary A thermodynamic analysis has been made of the secondary transition stage in the spontaneous precipitation of calcium phosphate following the amorphous-crystalline transformation. The first formed crystalline material has a solubility similar to that of octacalcium phosphate (OCP) and the computed thermodynamic solubility product remains invariant in the pH range 7.00–8.60. The duration of the secondary stage is sensitive to pH and the transition appears to occur by hydrolysis of the first formed OCP-like phase to a more basic apatitic phase with a tricalcium phosphate (TCP) stoichiometry. The crystalline material at the end of this transition has an invariant solubility product, in the pH range 7.00 to 8.60, when the TCP-like molecular formula is assumed. Changes in the solution chemistry which accompany the solid-tosolid transitions are consistent with the above conclusions. The results of this study are also consistent with those of a previous study which suggest that the stability of the amorphous calcium phosphate phase is dependent upon the instability of the solution phase with respect to OCP formation.
    Type of Medium: Electronic Resource
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