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  • 1990-1994  (2)
  • 14.80.Pb  (1)
  • myocardial perfusion  (1)
  • Rare earth elements
  • 1
    Electronic Resource
    Electronic Resource
    Limits for two-photon ande + e − decay widths of positron-electron scattering resonances for√s=1.78 to 1.92 MeV (1991)
    Springer
    The European physical journal 340 (1991), S. 209-218 
    Details
    ISSN: 1434-601X
    Keywords: 14.80.Pb ; 13.10. + q ; 12.20.Fv
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Motivated by the observation of energy- and momentum-correlatede + e − pairs in heavy ion collisions, a search for resonances ine + e − scattering at the corresponding energies has been made. Thee + e − decay channel is analyzed in a time window from ∼ 10−13 s to ∼ 10−11 s with a set-up optimized for low-background detection of delayede + e − decays. The two-photon decay channel of a hypothetical resonance is investigated by measuring the two-photon annihilation-in-flight excitation function. New upper limits for the partiale + e − decay width Γee of a few meV are derived for total centre-of-mass energies √s between 1.78 and 1.92 MeV, taking into account the dilepton as well as the two-photon decay of a neutral resonance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01303834
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Myocardial perfusion measured by dual-isotope acquisition of81rubidium/81mkrypton: an experimental verification of the method (1994)
    Springer
    Basic research in cardiology 89 (1994), S. 354-365 
    Details
    ISSN: 1435-1803
    Keywords: 81Rubidium/81mkrypton ; myocardial perfusion ; myocardial perfusion reserve ; isolated rabbit heart ; Langendorff preparation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Purpose The purpose of the study was to verify that the81Rubidium/81mkrypton (81Rb/81mKr) method allows the quantitative measurement of myocardial perfusion. Principle The potassium analogous cation81Rb is accumulated in the myocardium by the cell membrane-bound Na−K-ATPase. After accumulation an intracellular equilibrium establishes between81Rb and its radioactive daughter nuclide81mKr. The flow-sensitive method evaluates the disturbance of this equilibrium by perfusion which washes out the short-lived diffusable daughter nuclide81mKr while the mother nuclide81Rb remains cell-bound. Methods Isolated rabbit hearts were prepared in a modified Langendorff technique which allowed quantitative collection of the coronary sinus efflux. The myocardium was labeled with pure81Rb by bolus injection into the aortic cannula. Spectroscopic measurements of81Rb and81mKr gamma radiation were performed using a germanium detector. Perfusion was varied in the range between 0 and 4 ml/min/g. The activity ratio81Rb/81mKr was determined and compared with coronary sinus effusion. Results 81Rb/81mKr activity ratio was closely related (r=0.98) to perfusion as described by the predicted equation Rb/Kr=(F/2.96 P)+1. (Rb/Kr=activity ratio between81Rb and81mKr in the myocardium; F=myocardial perfusion (ml/min/g); P=partition coefficient (myocardium/perfusate) for Krypton gas.) The constant P was found to be 1.14±0.06 (mean±SEM). No saturation of this ratio at high flow rates was observed. Conclusion The activity ratio81Rb/81mKr is a valid quantitative measure for myocardial perfusion in isolated hearts. The main limitation of the method before application in man is the correction of the different gamma ray tissue absorption of both nuclides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00795203
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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