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  • 1
    Electronic Resource
    Electronic Resource
    Hypothermia and blood flow behavior (1973)
    Springer
    Research in experimental medicine 161 (1973), S. 58-68 
    Details
    ISSN: 1433-8580
    Keywords: Aggregometry ; Apparent blood viscosity ; Erythrocyte aggregation ; Erythrocyte deformability ; Hemoglobin viscosity ; Hypothermia ; Plasma viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Mikrorheologie und Viscosität von Vollblut, Erythrocyten und Erythrocytenaggregaten wurden bei Temperaturen zwischen 37 und 4°C untersucht. Neben lange bekannten Viscositätssteigerungen von Blut und Plasma beihohen Schergraden wurde ein spezieller Anstieg der Blutviscosität (nicht Plasmaviscosität) beiniedrigen Schergraden und Temperaturen unter 20°C beobachtet. Dieser Anstieg fehlt in nichtaggregierenden Blutproben (Erythrocyten in isotonischer Albuminlösung). Im gleichen Temperatur- und Schergradbereich wurde regelmäßig eine starke Zunahme der Aggregationstendenz beobachtet. Die Schubspannungen, die zur Dispersion von Aggregaten notwendig sind, steigen von 3 dyn/cm2 bei 37°C auf 10 dyn/cm2 bei 4°C. Die Verformbarkeit der Zellen, getestet an ihrer Fähigkeit, durch 5 µm Poren zu fließen, ist jedoch nicht aufgehoben. Diesein vitro-Ergebnisse unterstützen die Vorstellung, daß die Mikrozirkulationsstörungenin vivo nach Hypothermie tatsächlich auf gesteigerter Aggregationstendenz der Erythrocyten beruht.
    Notes: Summary The microrheology and bulk viscosity of whole blood, erythrocytes and erythrocyte aggregates was examined at temperatures between 37 and 4°C. Beside the well established increases of blood and plasma viscosity athigh rates of shear, a specific increase of blood (not plasma) viscosity atlow rates of shear is seen below 20°C. This increase is not seen in non-aggregating blood samples (red cells in isotonic albumin solution). At the same temperature and shear rate range, a strong increase in the tendency to aggregation is regularly observed. The shear stresses necessary to keep red cell aggregates dispersed in flow increase from 3 (at 37°) to 10 dynes/cm2 (at 4°C). The deformability of the cells as tested by their ability to pass 5 µm pores is, however, not abolished by lowering temperatures. Thesein vitro results give strong support to the notion that the microcirculatory disturbances seen in response to hypothermiain vivo are indeed related in part to increased tendency to red cell aggregation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01851023
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  • 2
    Electronic Resource
    Electronic Resource
    Digital radiography Results of a survey (part A) and a consensus conference (part B) (1997)
    Springer
    European radiology 7 (1997), S. S94 
    Details
    ISSN: 1432-1084
    Keywords: Key words: Digital radiography ; Storage phosphor radiography ; Digital image intensifier radiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Digital imaging (digital image intensifier radiography, storage phosphor/selenium radiography) is increasingly becoming commonplace in radiology departments for diagnostic purposes. Despite 10 years of experience, the advantages and disadvantages of those methods are still heavily discussed among users, financiers and prescribers. This paper is to offer additional arguments for a thorough and objective discussion. No further comments or interpretations have been added to this paper. This paper consists of two main parts, A and B. The first part deals with the results of a user survey, the other part presents the results, i. e. statements, of a consensus conference.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00006872
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  • 3
    Electronic Resource
    Electronic Resource
    Microrheology and light transmission of blood (1975)
    Springer
    Pflügers Archiv 354 (1975), S. 319-337 
    Details
    ISSN: 1432-2013
    Keywords: Red Cell Aggregation ; Rouleaux ; Photometry of Blood ; Viscometry of Blood ; High Molecular Weight Dextrans ; Low Molecular Weight Dextrans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Employing both microscopic and photometric methods the rheology of pathological red cell aggregation was studied in model experiments. Suspensions of washed human red blood cells in dextran solutions containing rising concentrations of dextrans (M.W. 40000, 70000, 110000, 250000, 500000) were used. At low concentrations (〈500 mg-%) of high molecular weight dextrans (〉70000)red cell suspensions formed aggregates similar to the ones found in normal human blood. At higher concentrations, the aggregates were similar to those observed in pathological human blood. The aggregates were studied under the condition of stasis, slow flow and at shear rate of their hydrodynamic dispersion. Besides, the flow behavior of the dispersed cells at high shear rates was studied. We found: 1. In all samples the rate of spontaneous aggregate re-formation in stasis (following hydrodynamic desaggregation) rose with rising dextran concentration up to 5.0 g-%. 2. The shear resistance of the aggregates, as measured by the shear stress necessary to keep them dispersed, rose up to concentrations of 2.5 g-%, but fell at higher concentrations. 3. Only with dextran of a molecular weight above 110000 coarse agglomerates could be produced at high concentrations. Loose elastic meshes were rapidly produced at high concentrations of Dx 70. 4. When subjected to steady state low shear (7 sec−1) only the agglomerates, but not the meshes rapidly grew in size. Most of the aggregation kinetics recorded by photometry and microscopy evaded detection by viscometry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00587850
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  • 4
    Electronic Resource
    Electronic Resource
    Red cell aggregation in blood flow (1976)
    Springer
    Journal of molecular medicine 54 (1976), S. 149-157 
    Details
    ISSN: 1432-1440
    Keywords: Blutrheologie ; arterielle Verschlußkrankheiten ; Diabetes mellitus ; Myelom ; photometrische Aggregometrie ; Rouleaux-Bildung ; Rouleaux-Klumpen ; Rouleaux-Netzwerke ; scheinbare Blutviskosität ; Schwangerschaft ; Apparent blood viscosity ; arterial vascular disease ; blood rheology ; diabetes mellitus ; myeloma ; photometric aggregometry ; pregnancy ; rouleaux clumps ; rouleaux formation ; rouleaux networks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary The rheological behavior of normal and pathological red cell aggregates in viscometric flow (artificial flow in cone plate chamber) is studied by direct microscopy, (rheoscopy) viscometry and photometry. Marked differences between normal and pathological blood are measured in the microrheological properties of red cell aggregates; only discreet differences are measured by blood viscometry (macrorheology). Both in normal and abnormal blood, red cell aggregation is a reversible process in the presence of adequate shear forces; their respective influences on apparent blood viscosity at low rates of shear are complex functions of shear rate, shear time, hematocrit and plasma viscosities. Pathological red cell aggregation (RCA) forms more rapidly and extensively than normal RCA. The pathological aggregates frequently have a tendency to grow at low rates of shear and they are highly shear resistant.
    Notes: Zusammenfassung Das rheologische Verhalten von normalen und pathologischen Erythrocytenaggregaten in viskometrischer Strömung (künstliche Strömung in Platte-Kegel-Kammer) wird mittels direkter mikroskopischer Beobachtung (im „Rheoskop“), Viskometrie und Photometrie untersucht. Erhebliche Unterschiede finden sich bei dem mikrorheologischen Verhalten, während im makrorheologischen Verhalten (Blut-Viskometrie) nur diskrete und oft komplexe Differenzen zwischen normalen und pathologischem Blut gemessen werden. Sowohl im normalen wie im pathologischen Blut ist die Erythrocytenaggregation ein reversibler Prozeß, vorausgesetzt, daß ausreichende Scherkräfte vorhanden sind. Der Einfluß der normalen und pathologischen Aggregate ist eine komplexe Funktion des Schergrades, der Scherzeit, des Hämatokritwertes und der Plasmaviskosität. Pathologische Erythrocytenaggregate bilden sich schneller und extensiver aus als normale Aggregate. Sie haben oft eine Tendenz, bei langsamer Strömung zu wachsen und sind hochgradig scherungsresistent:
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01468879
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  • 5
    Electronic Resource
    Electronic Resource
    Red cell aggregation in blood flow (1976)
    Springer
    Journal of molecular medicine 54 (1976), S. 159-167 
    Details
    ISSN: 1432-1440
    Keywords: Blutrheologie ; Fahraeus-Effekt ; Rouleaux-Klumpen ; Rouleaux-Netzwerke ; scheinbare Blutviskosität ; scheinbare relative Blutviskosität ; Viscosimetrie ; Apparent blood viscosity ; blood rheology ; Fahraeus-effect ; relative apparent blood viscosity ; rouleaux clumps ; rouleaux networks ; viscometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary The apparent viscosity of blood strongly increases at low shear in rotational viscometers, this phenomenon is based on the reversible formation of red cell aggregates. The magnitude of this increase strongly depends on the hematocrit value, on plasma viscosity and lastly on the microrheological properties of the aggregates. The independent measurement of the microrheological behavior and the effects on viscosity allows a detailed analysis of the hemodynamic effects of red cell aggregates under defined flow conditions in vivo. The comparative analysis shows that the conventional viscometry strongly underestimates the rheological differences between normal and pathologically intensified aggregation. Based on detailed analysis under defined flow conditions in vitro, the biological significance of viscometric results and the hemodynamic relevance of red cell aggregates are discussed.
    Notes: Zusammenfassung Die scheinbare Viskosität des Blutes steigt bei langsamer Scherung in Rotationsviskosimetern durch die reversible Bildung von Erythrocytenaggregaten sehr stark an. Das Ausmaß des Viskositätsanstiegs hängt jedoch wesentlich von dem Hämatokritwert, daneben von der Plasmaviskosität und schließlich von den mikrorheologischen Eigenschaften der Aggregate ab. Die unabhängige Messung der mikrorheologischen Eigenschaften und des Viskositätsverhaltens erlaubt die detaillierte Analyse des hämodynamischen Effektes von Erythrocytenaggregaten unter definierten Fließbedingungen in vitro. Die vergleichende Analyse zeigt, daß die konventionelle Viskosimetrie die rheologischen Unterschiede zwischen normaler und pathologisch gesteigerter Aggregation eindeutig unterschätzt. Basierend auf der detaillierten Analyse unter definierten Bedingungen in vitro werden die biologische Bedeutung von viskometrischen Befunden und die hämodynamische Relevanz von Erythrocytenaggregaten abgehandelt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01468880
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  • 6
    Electronic Resource
    Electronic Resource
    Ein Nierenpräparat (sog. Halsniere) zur Erleichterung komplizierter Funktionsuntersuchungen (1967)
    Springer
    Pflügers Archiv 297 (1967), S. 71-88 
    Details
    ISSN: 1432-2013
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Um eine experimentellen Eingriffen leicht zugängliche Niere zu erhalten, wurde eine Hundeniere an die Halsgefäße eines Perfusionstieres transplantiert (Homotransplantat). Eine nur kurze Kreislaufunterbrechung wurde durch die Verwendung von sogenannten Payr-Kanülen zur Anastomosierung der Gefäße erreicht. Funktionen der Nieren des Perfusionstieres dienten zur Kontrolle der Halsnieren. Nach einer etwa fünfstündigen Erholungsphase zeigten das Glomerulumfiltrat und die Harnosmolarität keine und die Exkretion von Wasser, Natrium, Kalium, Harnstoff und Kreatinin nur geringe Unterschiede zu den Werten der Nieren in situ. Die Halsnieren erreichten Glomerulumfiltrate von durchschnittlich 65 ml/min · 100 g und ein U/Posmol bis 7. Damit scheint das Halsnierenpräparat für Untersuchungen verschiedener Art (Extraktionsmessungen, Änderung der Nierenhämodynamik, Mikropunktionen) sehr geeignet.
    Notes: Summary In order to obtain an easily accessible experimental kidney a dog kidney was transplanted to the neck of a second dog. By the use of Payr-canulas the ischemic period of the transplanted kidney was considerably shortened. The normal in situ kidneys were used as controls to evaluate the function of the neck kidney. After a recovery period of about 5 hours, GFR and urine osmolarity of the neck kidney did not show any differences when compared with the in situ kidneys, while the excretion of water, Na, K, Urea, and creatinine differed only slightly. GFR of the neck kidneys averaged 65 ml/min · 100 g and the maximum measured U/Posmol was 7. Accordingly, the neck kidney preparation appears to be highly suitable for many kinds of experimental work (measurement of extraction ratios, renal hemodynamics, micropuncture etc.).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00363631
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  • 7
    Electronic Resource
    Electronic Resource
    Die Konzentrierung des Harnstoffes in der Niere (1969)
    Springer
    Pflügers Archiv 310 (1969), S. 320-336 
    Details
    ISSN: 1432-2013
    Keywords: Ureainfusion ; Osmolality of Final Urine ; Non Urea Solute Concentration ; Balance of Water ; Water Conservation ; Harnstoffinfusion ; Osmotische Endharnkonzentrierung ; Konzentrierung der Nichtharnstoffteilchen ; Wasserbilanz ; Wassrkonservierung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung An wachen Hunden wurde 24 Std nach der letzten Nahrungs-und Wasseraufnahme die Rolle des Harnstoffes in der Harnkonzentrierung untersucht. Die Harnstoffplasmakonzentration (P U ) wurde durch eine hypertone Harnstoffinfusion über 10–11 Std kontinuierlich erhöht. Um den Einfluß einer unterschiedlichen Natriumzufuhr auf die Harnkonzentrierung auszuschließen, wurden die Hunde vor dem Harnstoffinfusionsexperiment natriumarm ernährt. 1. P U steigt während der Infusion von 5 auf 20 mmol/l an. Gleichzeitig nimmtU/P osm von 3,8 auf 5,1 zu, was ausschließlich auf einer vermehrten Ureakonzentration (U U ) im Harn beruht. (U U steigt im Mittel von 403 auf 1107 mmol/l.) 2. Bis zu einemP U von 10 mmol/l steigt dazuU U proportional an. BeiP U 〉10 mmol/l ist der weitere Anstieg vonU U nur noch geringfügig. 3. Das Glomerulumfiltrat bleibt während der Infusion unverändert. 4. Nach 72 Std Fasten und Dursten erreichenU/P osm undU U annähernd gleiche Werte wie bei erhöhtemP U , jedoch sind an der Harnkonzentration alle osmotisch bedeutsamen Substanzen beteiligt. Die Harnkonzentrierung wird unter diesen Bedingungen nicht durch ein erhöhtes Harnstoffload, sondern durch eine vermehrte Wasserresorption bewerkstelligt. 5. Es wird geschlossen, daß eine selektive Ureakonzentrierung proportional zur Loaderhöhung erfolgt und daß Harnstoff keinen fördernden Effekt auf die Wasserresorption und die Konzentrierung der Nichtharnstoffbestandteile des Urins besitzt.
    Notes: Summary The role of urea in the concentrating process of the kidney was studied in conscious dogs. Food and water were withdrawn 24 hours before the experiments. An increase of plasma urea concentration (P U ) was obtained by constant intravenous infusion of a hypertonic urea solution over a period of 10–11 hours. In order to exclude the influence of a variable sodium intake the dogs were kept on a low sodium diet for a period of 4 weeks preceeding the experiment. 1. Infusion of urea results in an increase ofP U from 5 to 20 mmol/l. During the same periodU/P osm rises from 3.8 to 5.1. This effect is entirely due to a higher urine urea concentration. (U U rises from 403 to 1107 mmol/l.) 2. A linear correlation betweenP U andU U up to anP U of 10 mmol/l is observed. 3. There is no change in GFR during the infusion of urea. 4. 72 hours without water and food intake results in anU/P osm andU U which is similar to the values obtained during increasedP U . 5. From the data it is concluded that there is a selective urea concentrating process which is linearly correlated to the urea load. Urea does not stimulate water reabsorption, and does not increase the concentrating ability of the kidney for non-urea solutes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00587242
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  • 8
    Electronic Resource
    Electronic Resource
    Microrheology and light transmission of blood (1972)
    Springer
    Pflügers Archiv 333 (1972), S. 126-139 
    Details
    ISSN: 1432-2013
    Keywords: Blood Photometry ; Blood Viscosity ; Red Cell Aggregation ; Red Cell Deformation ; Red Cell Orientation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The well known flow dependence of the optical density of whole blood was studied by measuring light transmission of blood in viscometric flow. A cone-plate chamber (3° cone angle) was transilluminated (λ=500–800 nm) while under shear (0–460 sec−1). The transmitted light was monitored with a selenium barrier layer photocell and was continuously recorded. In an identical chamber, the microrheological behaviour of the cells in flow was monitored by microphotography and then correlated to photometric events. Light transmission of human blood showed a biphasic behaviour when plotted as a function of shear rate: between 0 and about 60 sec−1, the light transmission decreases with shear, corresponding to aggregate dispersion. Above 60 sec−1, an increase of light transmission with shear occurs, corresponding to red cell deformation, alignment, and orientation. Bovine blood, which does not form aggregates, shows minimum light transmission at rest. Light transmission then rises progressively with shear from the very onset of slow flow. Equine blood (equus zebra) which has very strong aggregation shows a progressive decrease of light transmission with shear due to aggregate persistence up to 460 sec−1. Amphibia blood (rana esculanta) shows very pronounced increase in light transmission at low shear rates, but no progression with shear. The nucleated amphibia erythrocytes are oriented but not deformed in flow. Rigidified cells which neither aggregate nor become oriented in flow show no flow dependent changes in light transmission. It became evident that in all blood samples minimum light transmission was recorded when the cells were dispersed and randomly oriented; both aggregation and orientation produced increased light transmission. These results explain earlier controversies in the literature, they shed doubt on the existence of a “tubular pinch effect” in whole blood rheology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00586912
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  • 9
    Electronic Resource
    Electronic Resource
    Microrheology and light transmission of blood (1972)
    Springer
    Pflügers Archiv 333 (1972), S. 140-155 
    Details
    ISSN: 1432-2013
    Keywords: Blood Photometry ; Blood Rheology ; Aggregation of Red Cells ; Rouleaux Formation ; High Molecular Weight Dextran
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The non-Newtonian viscosity of blood is caused by aggregation of red cells into three dimensional structures at low shear rates, causing high viscosity and the yield shear stress, progressive dispersion of these aggregates and eventually fluid drop-like transition of red cells at high rates of shear. Both the aggregated and the fluid drop-like state of the red cell can be characterized by the effect on apparent viscosity and by direct microscopic observation of the flowing blood. However, the transition between these two rheological states of the red cell could previously not be quantified. By monitoring their optical effects (as measured by light transmission under flow) rather than their mechanical effects (as measured by viscometry) the shear rates and thus the shear stresses necessary to keep red cell aggregates dispersed were determined. In addition, the degree of red cell aggregation at slow flow and the rate of aggregate reformation were quantified. After plasma dilution, all effects of red cell aggregation were less pronounced; after the addition of high molecular weight dextran, all effects of red cell aggregation were more pronounced. Lowering temperature down to 2°C intensified red cell aggregation, the shear stresses necessary to keep aggregates dispersed increased 8.5 times. This method allows for the first time to quantify under flow the kinetics of intensified red cell aggregation, the most common hemorhelogical abnormality.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00586913
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  • 10
    Electronic Resource
    Electronic Resource
    Chlamydia trachomatis als Erreger einer Neugeborenenpneumonie (1980)
    Springer
    Infection 8 (1980), S. 123-125 
    Details
    ISSN: 1439-0973
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary A report is given of a newborn who developed signs of hepatitis two weeks after a normal birth, and only later respiratory symptoms of pneumonia. The infant had pronounced tachypnea, increased immunoglobulins, eosinophilia and leucocytosis. X-rays in the initial stages showed interstitial infiltrates with alveolar hyperaeration, and in the later stages patchy alveolar infiltrates.Chlamydia trachomatis was cultured from the tracheal secretion. In making a differential diagnosis in cases of neonatal pneumonia, infection withtrachomatis must thus also be considered.
    Notes: Zusammenfassung Es wird über ein Neugeborenes berichtet, das 14 Tage nach einer normalen Geburt unter den Zeichen einer Hepatitis erkrankte und später erst respiratorische Symptome einer Pneumonie entwikkelte. Es hatte eine ausgeprägte Tachypnoe, Erhöhung der Immunglobuline, Eosinophilie und Leukozytose. Das Röntgenbild zeigte anfangs eine interstitielle Infiltration mit alveolärer Überblähung, später alveoläre Verdichtungen. Aus dem Trachealsekret konnteChlamydia trachomatis gezüchtet werden. In der Differentialdiagnose der Pneumonie des Neugeborenen muß damit auch eine Infektion mittrachomatis in Erwägung gezogen werden.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01641478
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