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  • 1
    Electronic Resource
    Electronic Resource
    Effect of coronary hyperperfusion on regional myocardial function and oxygen consumption of stunned myocardium in pigs (1991)
    Springer
    Basic research in cardiology 86 (1991), S. 534-543 
    Details
    ISSN: 1435-1803
    Keywords: Greggphenomenon ; regionalfunction ; stunnedmyocardium ; myocardialoxygenconsumption ; reperfusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The “Gregg phenomenon” implies that myocardial function and oxygen consumption ( $$M\dot VO_2 $$ ) increase when coronary perfusion is enhanced within or above the autoregulatory range. We have recently demonstrated that the “Gregg phenomenon” has no significance for regional myocardial function and $$M\dot VO_2 $$ in anesthetized swine in situ. There is, however, some evidence that the “Gregg phenomenon” may exist within stunned myocardium. To test whether coronary hyperperfusion increases regional myocardial function and $$M\dot VO_2 $$ in stunned myocardium, in six anesthetized swine the left anterior descending coronary artery (LAD) was cannulated and perfused at constant pressure (CAP) using an extracorporal circuit. The coronary vein which parallels the LAD was cannulated to allow measurement of regional $$M\dot VO_2 $$ and regional systolic wall thickening (WT%) of the anterior myocardium was assessed using sonomicrometry. Blood flow (CBF) to the LAD was increased by increasing CAP within the extracorporal circuit or by intracoronary adenosine infusion (150 μg/min). In normal myocardium, increasing CBF from 71.4 ± 19.7 (SD) to 156.7 ± 48.8 ml/min/100 g by increasing CAP from 100 ± 10 to 190 ± 10 mm Hg or increasing CBF from 75.1 ± 29.1 to 189.2 ± 45.8 ml/min/100 g by intracoronary adenosine infusion did not increase WT% (34.3 ± 12.2 % vs 32.1 ± 10.6 % and 32.3 ± 10.7 % vs 30.1 ± 13.2 %, respectively). $$M\dot VO_2 $$ was not changed during enhanced CAP (6.94 ± 1.05 vs 8.10 ± 1.08 ml/min/100 g) and during intracoronary adenosine infusion (6.67 ± 1.45 vs 7.30 ± 2.23 ml/min/100 g). Twenty min of hypoperfusion followed by 30 min of reperfusion depressed WT% by 47 % (p 〈 0.05). However, $$M\dot VO_2 $$ was only decreased by 23 % (NS). In the stunned myocardium, increasing CBF from 62.1 ± 36.4 to 157.1 ± 60.0 ml/min by increasing CAP was not associated with an increase in WT%. $$M\dot VO_2 $$ , however, increased from 5.14 ± 1.07 to 8.88 ± 1.83 ml/min/100 g (p 〈 0.05). Comparable results were achieved when CBF was increased from 60.3 ± 28.7 to 176.9 ± 48.5 ml/min by intracoronary adenosine infusion. WT% was unaffected, while $$M\dot VO_2 $$ increased from 4.69 ± 0.92 to 9.46 ± 3.39 ml/min/100 g (p 〈 0.05). Thus, increasing coronary perfusion within or above the autoregulatory range increases $$M\dot VO_2 $$ in stunned myocardium, but without a simultaneous increase in regional myocardial function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02190703
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  • 2
    Electronic Resource
    Electronic Resource
    Stunned myocardium: inotropic reserve and pharmacological attenuation (1995)
    Springer
    Basic research in cardiology 90 (1995), S. 294-296 
    Details
    ISSN: 1435-1803
    Keywords: Myocardial ischemia ; reperfusion ; inotropic reserve calcium antagonists ; ACE inhibitors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00797904
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  • 3
    Electronic Resource
    Electronic Resource
    Comparative study of nanocrystalline Ti2RuFe and Ti2RuFeO2 electrocatalysts for hydrogen evolution in long-term chlorate electrolysis conditions (1999)
    Springer
    Journal of applied electrochemistry 29 (1999), S. 551-560 
    Details
    ISSN: 1572-8838
    Keywords: ball-milling ; electrocatalyst ; hydrogen evolution ; nanocrystalline alloy ; sodium chlorate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Ti2RuFe and Ti2RuFeO2 nanocrystalline alloys were prepared by high energy ball-milling and used as cathodes for the hydrogen evolution reaction (HER) in the process of sodium chlorate synthesis. Ti2RuFe is almost single phase with the B2 structure. In contrast, Ti2RuFeO2 is made of a mixture of Ti2RuFe and TiOx phases. Tests in chlorate electrolysis conditions did not show any sign of degradation of Ti2RuFeO2 over a 300 h period, while Ti2RuFe breaks down after less than 100 h. The degradation of Ti2RuFe occurs because of hydrogen absorption and desorption during alternating hydrogen discharge and open-circuit conditions. Various hypotheses to explain the increase stability of the O containing alloy are considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026441532352
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  • 4
    Electronic Resource
    Electronic Resource
    Large specific surface area nanocrystalline Ti–Ru–Fe cathode materials for sodium chlorate (1999)
    Springer
    Journal of applied electrochemistry 29 (1999), S. 627-635 
    Details
    ISSN: 1572-8838
    Keywords: ball-milling ; electrocatalyst ; hydrogen evolution ; leaching ; lixiviation ; nanocrystalline alloys ; sodium chlorate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Ball-milled nanocrystalline Ti3RuFe powders were mixed with 1, 2, 4, 10 and 20 equivalents of Al and the mixtures were milled again for 20 h. The amount of Al atoms dissolved into the B2 structure of Ti3RuFe does not exceed 8–9 at %, the remaining being present as elemental Al into the powder mixture. During a subsequent treatment of the composite powder in alkaline solutions, the elemental Al is leached out, while Al solutes in the B2 structure are not affected. An examination of the surface by scanning electron microscopy reveals that the leached powder has a highly porous surface structure. Surface area measurements performed by BET measurements show that there is a tenfold increase in the effective surface area. Activated electrodes made from these porous materials show a significant decrease of the cathodic overpotential for hydrogen evolution in typical chlorate electrolysis conditions of about 80 mV.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026408502373
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of oxygen and titanium contents on the stability of nanocrystalline Ti–Ru–Fe–O cathode materials for chlorate electrolysis (2000)
    Springer
    Journal of applied electrochemistry 30 (2000), S. 491-498 
    Details
    ISSN: 1572-8838
    Keywords: ball milling ; chlorate electrolysis ; electrocatalysis ; hydrogen evolution ; nanocrystalline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Electrodes made from nanocrystalline Ti:Ru:Fe (2−y:1+y/2:1+y/2), with y varying from 0 to 1 by step of 0.25, and Ti:Ru:Fe:O (2:1:1:w), with w varying from 0 to 2 by step of 0.5, were prepared and tested as activated cathodes for the hydrogen evolution reaction in typical chlorate electrolysis conditions. These electrodes were subjected to an accelerated aging test, consisting of a succession of cycles of hydrogen discharge (HER) and open-circuit (OCP) conditions. In addition to monitoring the cathodic overpotential value during the aging test, visual inspection and mass loss measurements were performed on the electrodes at the end of the test to assess their stability. In the case of Ti:Ru:Fe (2:1:1), a large increase of the cathodic overpotential value is observed after 20 cycles. Adding O to the formulation causes a remarkable improvement of the long-term stability of the electrodes. As little as [O] = 10 at.% in nanocrystalline Ti:Ru:Fe:O (2:1:1:w) materials is sufficient for the electrode to show absolutely no sign of degradation after 50 cycles of HER/OCP, the longest accelerated test conducted. Adding more O to the formulation of the material does not lead to further stability improvement. A better stability under the conditions of the accelerated aging test can also be observed for nanocrystalline Ti:Ru:Fe (2−y:1+y/2:1+y/2) materials with y 〉 0. In that case however, the level of improvement is dependent on the value of y. The best results are obtained for y = 0.75. A hypothesis is proposed to explain the improved stability obtained by lowering the Ti content and/or by adding O. The similarity and difference between both ways of improving the stability of the nanocrystalline Ti:Ru:Fe materials are also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003961417762
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  • 6
    Electronic Resource
    Electronic Resource
    Ischemic preconditioning and myocardial hibernation: Is there a common mechanism? (1996)
    Springer
    Basic research in cardiology 91 (1996), S. 50-52 
    Details
    ISSN: 1435-1803
    Keywords: Myocardial ischemia ; reperfusion ; myocarial infarction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: In conclusion 1)Despite certain similarities between ischemic preconditioning and myocardial hibernation, these two cardioprotective phenomena are different in nature. 2) Intermittent reperfusion inbetween the preconditioning and the sustained ischemic period is not necessary for infarct size reduction by ischemic preconditioning.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00788864
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