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  • 1
    Electronic Resource
    Electronic Resource
    Agglutination kinetics of normal and diabetic adult rat hepatocytes (1980)
    Springer
    Pflügers Archiv 386 (1980), S. 245-250 
    Details
    ISSN: 1432-2013
    Keywords: Rat hepatocytes ; Streptozocin-induced diabetes ; Flocculation ; Sticking probability constant ; Agglutinin receptors ; Concanavalin A
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This paper describes Concanavalin A-induced agglutionation of viable rat hepatocytes obtained by collagenase perfusion from normal and streptozocin-treated diabetic rats. An irreversible cell-to-cell agglutination model is proposed to explain hepatocyte flocculation. The rate of agglutination is concentration dependent with respect to Concanavalin A, and is twice as fast in normal as compared to diabetic hepatocytes. Sticking probability constants ranging from 18.48×107 to 4.6×107 cm−1 · hepatocyte−1 and 8.32×107 to 2.31×107 cm−1 · hepatocyte−1 are calculated as a measure of agglutination for normal and diabetic cells respectively. These findings suggest that the cytoplasmic membranes of normal cells possess agglutinin receptors which are more numerous and/or differently arranged than those existing in diabetic cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00587475
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  • 2
    Electronic Resource
    Electronic Resource
    Educational technology in the Arab world (1986)
    Springer
    International review of education 32 (1986), S. 350-353 
    Details
    ISSN: 1573-0638
    Source: Springer Online Journal Archives 1860-2000
    Topics: Education
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02426071
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  • 3
    Electronic Resource
    Electronic Resource
    Coordinated optical and Yohkoh observations of 26 June 1992 flare loops (1994)
    Springer
    Space science reviews 70 (1994), S. 181-184 
    Details
    ISSN: 1572-9672
    Keywords: Flare loops ; Heating mechanisms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Optical spectra of large flare loops were detected by the Ondřejov Multichannel Flare Spectrograph (MFS) during coordinated observations with MSDP at Pic du Midi (Hα) and the soft X-ray telescope (SXT) on Yohkoh. The CCD video images taken by the MFS slit-jaw camera document the time-development of the flare loops as seen through the Hα filter. Preliminary analysis of the MSDP images shows the intensity structure of the cool flare loops and their velocity fields. From the spectra we can clearly see the intensity variations along the cool loops. SXT images show the structure of hot X-ray loops similar to that of cool loops. Special attention is devoted to the bright tops, simultaneously observed in X-rays, Hα and other optical lines. Based on a preliminary analysis of the optical spectra, we speculate about possible mechanisms leading to an observed bright emission at the tops of cool loops. We suggest that direct soft X-ray irradiation of cool loops at their tops could be, at least partly, responsible for such a strong brightening.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00777864
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  • 4
    Electronic Resource
    Electronic Resource
    Binding and distribution of three prototype calcium channel blockers in perfused rat liver (1997)
    Springer
    Molecular and cellular biochemistry 169 (1997), S. 1-11 
    Details
    ISSN: 1573-4919
    Keywords: liver cells ; calcium channels ; verapamil ; isradipine ; azidopine ; permeability constants ; binding constants ; residency time
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract This work represents a study of the binding and distribution of three different calcium channel blockers in the Sprague-Dawley rat liver, using an in situ perfusion technique. For this purpose, [3H] desmethoxyverapamil, [3H] PN200-110 (isradipine) and [3H] azidopine were used as binding probes interacting with calcium channels. The perfusion steps of the liver involved both portal vein and thoracic inferior vena cava cannulations as inlet and outlet respectively. The subhepatic inferior vena cava was ligated to prevent leakage of the perfusate. Buffer, containing the tracer drug, was administered via the portal vein at a rate of l mL/min and perfusate collected at the same rate within specified time intervals during 50 min. The concentration of the tracer solutes in the perfusate's outlet increased with time, and steady state was observed for all tracers at ≥ 40 min. The effect of adding cold isradipine to tracer desmethoxyverapamil, or cold verapamil to tracer PN200-110 were also assessed. First order rate constants for hepatocellular influx, efflux and calcium channel binding of the tracer substances were obtained using a simplified model from Goresky et al. [25]. These constants were mathematically manipulated and changed into permeability constants, second order binding constants, and residency times. Tracer solute influx across hepatocellular membranes is solubility-diffusion controlled, is inversely related to the molecular weights and is different in value from the efflux constants. Cold isradipine reduced the binding constant of desmethoxyverapamil by 36%, while cold verapamil reduced the binding constant of PN200-110 by 23%. Azidopine cellular distribution was low, however, binding to its receptor was analogous to desmethoxyverapamil and PN200-110. Moreover, PN200-110 had the highest residency time with no effect of cold verapamil on its receptor binding, while desmethoxyverapamil had the lowest residency time which significantly increased in the presence of cold isradipine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006879823866
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  • 5
    Electronic Resource
    Electronic Resource
    POST-FLARE LOOPS OF 26 JUNE 1992 – IV. Formation and Expansion of Hot and Cool Loops (1997)
    Springer
    Solar physics 174 (1997), S. 151-162 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Observations of the post-flare loops after the X3.9 flare which occurred on 25 June, 1992 at 20:11 UT by the Yohkoh/SXT in X-rays, as well as in Hα obtained at 5 different observatories, have provided a unique, longest ever, set of data for a study of the relationship between the hot and cool post-flare loops as they evolve. At any given time, the altitude difference between the hot X-ray loops of 6–7× 106 K and the cool Hα loops of 1.5× 104 K is related to the expansion rate of the loop systems and their cooling time. Therefore, measurements of the expansion rate and relative height of hot and cool loops can provide direct observational values for their cooling times. We measured the altitude of hot and cool loops for 15 and 19 hours, respectively, and found that the cooling time increased as the density of the loops decreased. We found a reasonably good agreement between the observed cooling times and those obtained from model calculations, although the observed values were always somewhat longer than the theoretical ones. Taking into account evolutionary effects, we also found similar shapes and configurations of hot and cool loops during the entire observing period and confirmed that, at any time, hot loops are at higher altitude than cool loops, suggesting that cool loops indeed evolve from hot loops. These results were used to check the validity of the reconnection model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004993809061
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  • 6
    Electronic Resource
    Electronic Resource
    Rapid sunspot motion during a major solar flare (1993)
    Springer
    Solar physics 147 (1993), S. 287-303 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A major solar flare on 15 November, 1991 produced a striking perturbation in the position and shape of the sunspot related most closely to the flare. We have studied these perturbations by use of the aspect-sensor images from the Soft X-ray Telescope on board YOHKOH, and with ground-based data from the Mees Solar Observatory. The perturbation occurred during the impulsive phase of the flare, with a total displacement on the order of 1 arc sec. The apparent velocity of approximately 2 km s−1 exceeds that typically reported for sunspot proper motions even in flare events. We estimate that the magnetic energy involved in displacing the sunspot amounted to less than 4 × 1030 ergs, comparable to the radiant energy from the perturbed region. Examination of the Mees Observatory data shows that the spot continued moving at lower speed for a half-hour after the impulsive phase. The spot perturbation appears to have been a result of the coronal restructuring and flare energy release, rather than its cause.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00690719
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  • 7
    Electronic Resource
    Electronic Resource
    Relation between cool and hot post-flare loops of 26 June 1992 derived from optical and X-ray (SXT-Yohkoh) observations (1995)
    Springer
    Solar physics 156 (1995), S. 337-361 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have analyzed the physical conditions of the plasma in post-flare loops with special emphasis on dynamics and energy transport using SXT-data (hot plasma) and optical ground-based data from Pic du Midi, Wrocław, and Ondřejov (cool plasma). By combining the Hα observations with the SXT images we can understand the relationship between cool and hot plasmas, the process of cooling post-flare loops and the mechanism which maintains the long duration of these loops. Using recent results of NLTE modeling of prominence-like plasmas, we derive the emission measure of cool Hα loops and this gives us a realistic estimate of the electron density (2.2 × 1010 cm−3). Then, by comparing this emission measure with that of hot loops derived from SXT data, we are able to estimate the ratio between electron densities in hot and cool loops taking into account the effect of geometrical filling factors. This leads to the electron density in hot loops 7 × 109 cm−3. We also derive the temperature of hot X-ray loops (≃ 5.5 × 106 K), which, together with the electron density, provides the initial values for solving the time-dependent energy balance equation. We obtain the cooling times which are compared to a typical growth-time of the whole loop system (∼ 2000 s). In the legs of cool Hα loops, we observe an excess of the emission measure which we attribute to the effect of Doppler brightening (due to large downflow velocities).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00670231
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  • 8
    Electronic Resource
    Electronic Resource
    Adsorption of concanavalin a on human platelets (1982)
    Springer
    Annals of biomedical engineering 10 (1982), S. 219-229 
    Details
    ISSN: 1573-9686
    Keywords: Concanavalin A ; Human platelets
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract A physiological cell surface absorption system approach is investigated on human platelets utilizing mathematical modeling. Monodispersed washed platelets are freshly collected in an isotonic buffer as a suspension utilizing a gel filtration technique. Concanavalin A is used as a glycoprotein receptor adsorbate in the adsorption studies. Three mathematical models are proposed based on simple chemical equilibrium reactions between adsorbate and cell surface receptors in an effort to explain concanavalin A—platelet surface glycoprotein interaction. Model I assumes that all receptors are undergoing simultaneous surface reactions with the adsorbate and without correlation. Model II reflects a strong correlation between the receptors, when only one receptor is active and the second receptor(s) is nothing but the combination of first receptor-adsorbate complex. Model III assumes the presence of multiple receptors on the cell surface. Only when a specific fraction of the total number of one receptor have reacted, will the other receptor(s) initiate reaction with the adsorbate. The results suggest the existence of at least three major glycoprotein receptors interacting with the lectin, and having different equilibrium constants as indicated in the adsorption isotherm. Model III seems to support best the experimental data of concanavalin A interaction with platelet surface glycoproteins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02367394
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