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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Lipids and Lipid Metabolism 919 (1987), S. 93-96 
    ISSN: 0005-2760
    Keywords: (Rat heart) ; Chemiluminescence ; Dietary fat ; Hydroperoxide ; Icosanoid release
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine , Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of statistical physics 63 (1991), S. 719-735 
    ISSN: 1572-9613
    Keywords: Attractive systems ; local equilibrium ; hydrodynamic equation ; entropy solutions ; Euler scaling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We extend previous results on the preservation of local equilibrium for one-dimensional asymmetric attractive particle systems. The hydrodynamic behavior is studied for general monotone initial profiles.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    The international journal of cardiovascular imaging 9 (1993), S. 7-19 
    ISSN: 1573-0743
    Keywords: contrast agents ; echocardiography ; indicator-dilution principles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Contrast echocardiography has the potential for measuring cardiac output and regional blood flow. However, accurate quantitation is limited both by the use of non-standard contrast agents and by the electronic signal distortion inherent to the echocardiographic instruments. Thus, the aim of this study is to quantify flow by combining a stable contrast agent and a modified echo equipment, able to sample the radio frequency (RF) signal from a region of interest (ROI) in the echo image. The contrast agent SHU-454 (0.8 ml) was bolus injected into anin vitro calf vein, at 23 flow rates (ranging from 376 to 3620 ml/min) but constant volume and pressure. The ROI was placed in the centre of the vein, the RF signal was processed in real time and transferred to a personal computer to generate time-intensity curves. In the absence of recirculation, contrast washout slope and mean transit time (MTT) of curves (1.11–8.52 seconds) yielded excellent correlations with flow: r=0.93 and 0.95, respectively. To compare the accuracy of RF analysis with that of conventional image processing as to flow quantitation, conventional images were collected in the same flow model by two different scanners: a) the mechanical sector scanner used for RF analysis, and b) a conventional electronic sector scanner. These images were digitized off-line, mean videodensity inside an identical ROI was measured and time-intensity curves were built. MTT by RF was shorter than by videodensitometric analysis of the images generated by the same scanner (p〈0.001). In contrast, MTT by RF was longer than by the conventional scanner (p〈0.001). Significant differences in MTT were also found with changes in the gain setting controls of the conventional scanner. To study the stability of the contrast effect, 6 contrast injections (20 ml) were performed at a constant flow rate during recirculation: the spontaneous decay in RF signal intensity (t1/2=64±8 seconds) was too long to affect MTT significantly. In conclusion, the combination of a stable con trast agent and a modified echocardiographic instrument provides accurate quantitation of flow in anin vitro model; RF analysis is more accurate than conventional processing as to flow quantitation by contrast echocardiography.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    The international journal of cardiovascular imaging 9 (1993), S. 21-27 
    ISSN: 1573-0743
    Keywords: attenuation ; contrast agents ; echocardiography ; indicator-dilution principles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The combination of a standardized echographic contrast agent with the analysis of the ultrasonic radio frequency (RF) signal allowedin vitro flow quantitation in a circulation model. The purpose of this study was to investigate both the effects of biological tissues, intervening between probe and insonated structure, and the effects of the angle of incidence between flow and ultrasonic beam on RF flow quantitation. Thus, the contrast agent SHU 454 was intravenously injected (0.4 ml) as a bolus into a circulation model, at variable flow rates, while keeping the pressure and volume of the vessel constant. Injections were performed with saline interposed between probe and vessel and after the addition of the subcutaneous tissue of a pig; injections were also performed using the probe normal to the flow and with an angle of incidence of 45°. Echographic data were recorded by a mechanical sector scanner, capable of sampling the RF signal from a region of interest positioned in the center of the vein. Contrast echo time-intensity curves were generated. As expected, both peak intensity and the area under the curves decreased with intervening tissue (− 58 and − 70% of baseline values, respectively, p〈0.001). Surprisingly, mean transit time also decreased with intervening tissue (from 1.12±0.25 seconds with saline, to 0.92±0.13 seconds with tissue, p〈0.001), thus producing a systematic overestimation of flow (21% on the average). To compensate for signal attenuation, contrast injections were repeated in the presence of tissue after increasing the electronic signal amplification (10 dB), and transit time did not significantly differ from control. Moreover, mean transit time was slightly shorter with an angle of 45° (1.03 ° 0.19 seconds) than with an angle of 90° (1.12±0.25 seconds, p〈0.05). However, when the data collected with both angles of incidence were plotted together, the correlation with flow remained very close (r=0.94). In conclusion: intervening tissue influences flow quantitation by contrast echocardiography: these modifications can be compensated for by increasing the electronic signal amplification; the angle of incidence between flow and ultrasonic beam also influences flow quantitation: however, this influence is trivial, and can be neglected for practical purposes.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1590-3478
    Keywords: Emery-Dreifuss disease ; X-linked inheritance ; fiber atrophy and predominance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Sommario Questa è la prima descrizione di madre e figlia affette da una infrequente malattia muscolare, caratterizzata da progressione lenta, ipostenia con atrofia a distribuzione omero-peroneale, presenza di contratture articolari, cardiopatia e pattern miopatico dell'EMG. Istologia e istochimica muscolare hanno mostrato in entrambi i soggetti atrofia e predominanza delle fibre del I tipo. Le anormalità cardiologiche rilevate nel 1° caso, erano a favore di una cardiomiopatia ipertrofica, mentre nel secondo caso erano presenti ipotensione e bradicardia. Segni neurologici, elettromiografici, reperti istologici ed istochimici sembrano configurare nelle nostre pazienti una variante genetica della forma di distrofia muscolare chiamata “Emery-Dreifuss disease”. Tuttavia, la modalità di trasmissione e il tipo delle anormalità cardiologiche, diverse nelle due pazienti, sollevano il problema di variabilità fenotipiche, anche in entità clinico-genetiche usualmente ben definite quali la malattia di Emery-Dreifuss.
    Notes: Abstract Two females mother and daughter, were affected by a neuromuscular disorder, characterized by slow progression, humeroperoneal weakness and wasting, limited neck flexion, elbow and ankle joint contractures, cardiopathy and myopathic pattern on EMG. Muscle histology and histochemistry showed type I fiber atrophy and predominance in both. Cardiac abnormalities, in the first case, were suggestive of a hypertrophic cardiomyopathy while in the second hypotension and chronic bradycardia were present. Neurological signs, EMG and morphology seemed to point to a genetic variant of the form of dystrophy named Emergy-Dreifuss disease. The mode of transmission and cardiac abnormalities, however, raise the problem of variability even in this well-defined, usually X-linked, disorder.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 16 (1978), S. 542-548 
    ISSN: 1741-0444
    Keywords: Computing ; Image analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Description / Table of Contents: Sommaire L'analyse d'images par les systèmes vidéo a fait l'objet depuis longtemps d'applications médicales et elle a été utilisée avec succès pour l'analyse des cinéangiogrammes. Dans la plupart des cas, l'instrumentation utilisée pour cette analyse est caractérisée par des systèmes d'ordinateurs relativement complexes. Etant donné l'intérêt que présente cette application, en particulier à la suite de la forte croissance enregistrée dans le domaine de la chirurgie cardiaque, qui nécessite un diagnostic anatomo-fonctionnel, il a semblé raisonnable d'envisager la possibilité de simplifier et standardiser l'instrument, en tenant compte des possibilités logicielles d'un petit ordinateur digital, en tenant compte de l'utilisation possible de microprocesseurs. Cet article présente un système minimum capable de traiter des images de télévision et utilisant un interface bon marché et des programmes généraux.
    Abstract: Zusammenfassung Die Bildanalyse mit Video-Systemen hat sich für den medizinischen Anwendungsbereich gut bewährt und wurde bei den Analysen von Kineangiogrammen mit Erfolg angewandt. In den meisten Fällen wurde die für diesen Zweck verwendete Meßgerätaursrüstung durch die relative komplexe Hardware charakterisiert. Aufgrund des gleichzeitigen Interesses dieser Anwendungsmethode in bezug auf das progressive Wachsen der Hertzchirurgie und dem damit verbundenen Bedarf an anatomisch funktionellen Diagnosen schien es einleuchtend, die Möglichkeit der Simplifikation und Standardisierung der Instrumentation durch Ausnutzung der Software-Möglichkeiten eines kleinen Digital-Computers sowie der möglichen Implementierung eines Miktroporozessors, in Erwagung zu ziehen. In diesem Papier wird ein Minimalsystem dargestellt, das mit einem preiswerten Computer-Koppelsystem und einem Allzweck-Softwarepaket Fernsehbilder verarbeiten kann.
    Notes: Abstract Image analysis by video systems is well established for medical applications, and its has been successfully used for the analysis of cineangiograms. In most instances the instrumentation used for this purpose has been characterised by relatively complex hardware set ups. Owing to the interest of this application, also in relation to the progressive growth of cardiac surgery and hence the need for anatomo-functional diagnosis, it seemed reasonable to consider the possibility of simplification and standardisation of the instrumentation, taking advantage of the software possibilities of a small digital computer and possible microprocessor implementation. The paper presents a minimum system capable of processing t.v. images, using an unexpensive computer interface and a general-purpose software package.
    Type of Medium: Electronic Resource
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