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  • 1970-1974  (14)
  • 1940-1944  (1)
  • 1
    ISSN: 1433-8580
    Keywords: Dilution curves ; Isotopes ; Flow measurement ; Volume determination ; Model experiments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Wir entwickelten auf Grund des mathematischen Modells von Newman et al. Berechnungsmethoden, um Flow oder Volumen unbekannter Mischkammern zu bestimmen. Um die Geometrieprobleme, die bei der Isotopenmessung auftreten, zu umgehen, schlagen wir Berechnungsmethoden vor, die unabhängig sind von der absoluten Größe der gemessenen Intensität. Diese Berechnungsmethoden, die durch ein Computerprogramm realisiert werden können, wurden in einem Kreislaufmodell untersucht. Das Modell bestand aus einer Kolbenpumpe als erster Mischkammer und zwei weiteren Mischkammern. Es konnte gezeigt werden, daß die Charakteristika der über diesen Kammern gemessenen Isotopenverdünnungskurven den Charakteristika errechneter Kurven entsprechen, daß Flow und Volumenberechnungen, die auf diesen Kurven basieren, nicht nur für kontinuierlichen, sondern auch für pulsatilen Flow gelten und daß diese Art der Flowmessung auch möglich ist, wenn ein Teil des Flows zwischen den Kammern abgezweigt wird.
    Notes: Summary Based on the mathematical model of Newmanet al. we developed calculation methods for the determination of flow or volume of unknown mixing chambers. To avoid the geometrical problems arising by monitoring isotopes we propose calculation methods independent from the absolute value of the measured intensity. These calculation methods which can be realized by a computer program are examined in a circulation model. The model consisted of a piston pump as first mixing chamber and two other mixing chambers. It could be demonstrated that the characteristics of the isotope dilution curves obtained over these chambers correspond to the characteristics of calculated curves and that the flow and volume calculations based on these curves are not only valid for the continuous flow but also for the pulsatile flow and that this type of flow measurement is also possible no matter how much of the flow is branched off between the chambers.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Acta neurochirurgica 27 (1972), S. 63-85 
    ISSN: 0942-0940
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Oedema were induced in rabbit brains by the application of cold metal to defined areas of intact dura for constant times. Trephine openings were made over the right cerebral hemispheres. 24 hours later the animals were killed, and identical pieces of occipital cortex from both hemispheres were removed. In all specimens we determined the water content, the water uptake of the sliced brain in vitro, and the glucose metabolism of the brain slices. Respiration, carbon dioxide production in the presence of bicarbonate, consumption of glucose, and production of lactate and pyruvate were measured. The incubations were made in physiological saline (with K+, Ca2+, Mg2+ and PO4 3- additions) in the presence of gas mixtures with different contents of oxygen. The mean difference of the water contents in vivo was 1.3%. The lowest water content after in vitro incubations was found in the presence of 95% O2 and 5% CO2. The oedematous tissue had a slightly stimulated respiration, and its aerobic glycolysis was markedly increased. These metabolic differences were observed only in the presence of 12% O2 and 5% CO2 and higher oxygen concentrations. In the presence of 4% O2 and 5% CO2 neither respiratory nor glycolytic differences existed between normal and oedematous tissue. A pronounced Pasteur effect was seen in all the experiments. Increase in glycolysis is a more sensitive indicator of oxygen lack than is decrease in respiration. During 150 min of incubation respiration and carbon dioxide production become slower. The decrease in total and glycolytic CO2 production is greater in slices of control hemispheres than in slices of oedematous hemispheres. The best correlation between metabolic activities determined by manometry and metabolic activities determined by glucose, lactate and pyruvate determinations was found in experiments in the presence of 4% O2 and 5% CO2. It is concluded that unsliced brain in the presence of air, at room temperature and below, has nearly the same respiration and glycolysis within the whole glucose degradation process as have brain slices at 38 °C in the presence of 4% O2 and 5% CO2. The conclusion is made that in vitro the best metabolic situation for brain slices, normal and oedematous, is between 20% and 95% of oxygen.
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  • 3
    ISSN: 0942-0940
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
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  • 4
    ISSN: 1433-8580
    Keywords: Dilution curves ; Flow measurement ; Isotopes ; Animal experiments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Es wurden Tierexperimente durchgeführt, um zu beweisen, daß es möglich ist, die Durchblutung eines peripheren Organs mit der Isotopenverdünnungsmethode nach i.v. Injektion zu messen. Es konnte gezeigt werden, daß die mathematische Beschreibung der Verdünnungsvorgänge in 3 Mischkammern in Reihe, die in einer vorhergehenden Arbeit dargestellt wurde, auch für den tierischen Organismus gilt, wo rechtes und linkes Herz sowie peripheres Capillargebiet als Mischkammern wirken. Die für den Verdünnungsvorgang im peripheren Organ errechnete Zeitkonstante ist umgekehrt proportional der Durchblutung, die mit einem elektromagnetischen Flowmeter gemessen wurde.
    Notes: Summary Animal experiments were carried out to prove that it is possible to estimate the blood flow through peripheral organs with the isotope dilution technique after intravenous injection. It could be shown that the mathematical treatment of the dilution events in three mixing chambers in a row, presented in a foregoing paper, is valid also for the animal organism where the mixing chambers are right heart, left heart and peripheral capillary system. The time constant calculated for the dilution event within the peripheral organ is inversely proportional to the blood flow through this organ measured with an electromagnetic flowmeter.
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  • 5
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Der Einfluss von Adenosin-3′, 5′- monophosphat (AMP) auf den Glukosestoffwechsel von Grosshirnrindenschnitten des Kaninchens wurde untersucht. 0.1 bis 1mM AMP pro Liter Incubationslösung stimulieren die Atmung der Schnitte. Die aerobe Glykolyse der Schnitte wird durch 0,5 bis 1 mM AMP anfänglich stark gesteigert und nach ca. 30 min völlig gehemmt. 0.1 mM AMP hemmt die Glykolyse lediglich.
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  • 6
    ISSN: 0942-0940
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In some cases of subdural effusions the common methods of treatment (subdural punctures, burr holes, shunting procedures and standard craniotomy) are ineffective. Usually in these cases a marked craniocerebral disproportion causes the persistence of the hygroma. In 14 of these cases with bilateral effusions the authors have used effectively an operative procedure, in which not only the inner membrane is removed but also the dural sac and the cranium is resected down to a size, where an optimal adaptation to the brain volume is achieved. The operative technique is illustrated and the long term results are presented. No major operative and postoperative complications occurred. The indication for this operative procedure is discussed with special regard to the current concepts in the literature.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Acta neurochirurgica 22 (1970), S. 109-111 
    ISSN: 0942-0940
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
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  • 8
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    Electronic Resource
    Springer
    Acta neurochirurgica 22 (1970), S. 167-175 
    ISSN: 0942-0940
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A circumscribed brain oedema was caused by the localized application of cold in the rabbit's brain. The metabolism of oedematous brain slices and analogous areas from the non-lesioned hemisphere were examined with the new 2-vessel method ofWarburg. In comparison with the uninjured brain, aerobic and anaerobic glycolyses were strongly increased in oedematous tissue, the respiration was slightly increased. These findings may be interpreted as the expression of an elimination of a previously existing energy deficit.
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  • 9
    ISSN: 0942-0940
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Our intention was to find out, if there is a difference between the cardiovascular responses to fast and slow increases in intracranial pressure. The investigations were carried out on dwarf pigs and included recordings of intracranial pressure, systemic blood pressure, pulmonary venous pressure, right and left atrial pressures, cardiac output, and heart rate. The results seem to indicate that a rapid rise in intracranial pressure provokes mainly peripheral vasoconstriction, whereas slow intracranial compression leads to marked augmentation of cardiac efficiency and strokework, the peripheral resistance being changed little or not at all.
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  • 10
    ISSN: 0942-0940
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We induced oedema in rabbit brains by applying cold to a defined area of the intact dura for a constant time. 24 hours later the animals were killed, and a piece of brain cortex adjacent to the region of cold application and an exactly similar piece from the other hemisphere were removed. In both pieces we determined the water content, the water uptake of the sliced brain in vitro, and the glucose metabolism of the brain slices. Respiration, carbon dioxide production in the presence of bicarbonate, consumption of glucose, and production of lactate and pyruvate were measured. The incubations were made in physiological saline with different concentrations of glucose (2.5 ml, 5 mM, and 10 mM). The mean difference of the water contents in vivo was 1.9%. The water uptake in vitro did not depend on the glucose concentration. The oedematous tissue had a slightly stimulated respiration, and its aerobic glycolysis was markedly increased. The respiration was independent of the glucose concentration. The lactate: pyruvate quotient was somewhat higher on the oedematous side, and it became greater on both sides with increasing glucose concentration. The glycolysis increased considerably between 2.5 mM and 5 mM glucose, especially in the oedematous brain. Between 5 mM and 10 mM glucose the aerobic glycolysis was accelerated only slightly by increasing glucose concentration. We think that the increased glycolysis is an expression of a preceding energy deficit. By a simple enhancement of the glucose concentration to more than 100 mg/100 ml the metabolism is not stimulated further, and the water content is not diminished.
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