Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Effects of Acholeplasma laidlawii and an unidentified mycoplasma on selected fish cell cultures and the replication of fish viruses (1979)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish diseases 2 (1979), S. 0 
    Details
    ISSN: 1365-2761
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Abstract. An unidentified mycoplasma was isolated from cultures of Atlantic salmon (AS) cells and implicated as the cause of cytopathic effects (CPE). The agent did not visibly affect RTG-2 cells. Experimental infection of RTG-2 cells with Acholeplasma laidlawii resulted in increased cellular granularity and destruction. Scanning electron microscopic (SEM) examination of infected RTG-2 and AS cultures revealed typical mycoplasmas distributed on cell surfaces and a marked effect on the cell surface topography, characterized by a loss of microvilli and cellular processes. SEM also revealed mycoplasmal contamination that was not detected by culturing. Comparisons of contaminated and uncontaminated RTG-2 cells showed enhanced (2–100 fold) replication of infectious pancreatic necrosis virus (IPNV) and infectious haematopoietic necrosis virus (IHNV) in the presence of A, laidlawii.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2761.1979.tb00162.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    The effects of diphenylhydantoin on mechanical and electrical properties of isolated cat myocardium (1977)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 298 (1977), S. 273-282 
    Details
    ISSN: 1432-1912
    Keywords: Diphenylhydantoin ; Cardiac muscle ; Inotropic effects ; Antiarrhythmic action
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of diphenylhydantoin (DPH) (4×10−5 to 2×10−4M) on contractile activity and electrical properties were studied in isotonically shortening cat papillary muscles exposed to DPH. 1. DPH reduces amplitudes of contraction especially at low stimulation rates (6 to 12/min). At higher, more physiological rates the negative inotropic effect is comparatively small. 2. DPH accentuates the mechanical transients usually following step changes of frequency. 3. DPH reduces the maximum rate of depolarisation (MRD) of the normal action potential (AP) and slows conduction especially at high stimulation rates. AP duration is shortened especially at low stimulation rates. 4. In Ca-mediated “slow responses” DPH reduces MRD, overshoot and AP duration and abolishes the frequency-dependent alterations of these parameters. 5. The results suggest that the antiarrhythmic potency of DPH is due to a cooperative action on both the fast and the slow membrane channels. 6. It is speculated that DPH leads to an accumulation of Ca2+ within a “limited subsarcolemmal space” thereby decreasing the driving force for the slow inward current.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00500900
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Inotropic and electrophysiological actions of verapamil and D 600 in mammalian myocardium (1975)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 290 (1975), S. 69-80 
    Details
    ISSN: 1432-1912
    Keywords: Verapamil ; D 600 ; Optical Isomers ; Cardiac Muscle ; Inotropic Effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary On isotonically contracting cat papillary muscles using pattern analysis, a comparison of the effects of the optical isomers of verapamil and D 600 and the racemic drugs was periormed. 1. (-)-verapamil (0.2–0.3 μg/ml) and (-)-D-600 (0.1 μg/ml–3.0 μg/ml) leave the steady state contraction amplitudes nearly, unchanged at 6/min, but produce a strong depression at 60/min. (-)-D 600 is about 8 times as effective as (-)-verapamil. The (+)-isomers exert only a moderate negative inotropic effect (particularly at low frequencies). 2. Increase of [Ca2+]0 does not restitute the normal amplitude-frequency relationship during exposure to either the (-)-isomers or the (+)-isomers. 3. The (-)-isomers lead to typical biphasic staircases after step changes of frequency. A fast negative staircase occurs first followed by a rather slowly developing positive staircase. In contrast, the (+)-isomers have little influence on the usual staircase pattern. 4. The strength-interval relationship for single test contractions elicited after frequent conditioning stimulation indicated that the (-)-isomers probably slow the restitution of intracellular Ca-reavailability. The (+)-isomers have no such effects. 5. The effects produced by the (±)-compounds correspond qualitatively to those of the (-)-isomers. 6. The very different patterns of inotropic actions observed indicate that the (-)- and (+)-isomers of verapamil and D 600 probably interfere with cardiac excitation-contraction coupling at different sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00499990
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    The effects of nifedipine on contraction and monophasic action potential of isolated cat myocardium (1977)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 301 (1977), S. 29-37 
    Details
    ISSN: 1432-1912
    Keywords: Nifedipine ; Mammalian cardiac muscle ; Amplitude-frequency relationship ; Staircase phenomena ; Transmembrane action potential ; SA-nodal rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. The effects of nifedipine (3×10−11–3×10−6 M) on contractile activity and transmembrane action potential (AP) were studied in isotonically contracting cat papillary muscles and in isolated SA-nodes. 2. Nifedipine (3×10−8–3×10−6 M) reduces the amplitudes of contraction. The effect is nearly independent of stimulation rate such that at 6/min the ED50 amounts to 6.1×10−7 M as compared to 5.1×10−7 M at 60/min. This negative inotropic action can be nearly completely antagonized by raising [Ca2+] o . 3. Nifedipine induces short-lasting negative stair-cases developing upon step increases of stimulation rate. Raising [Ca2+] o does not counteract this effect. 4. Nifedipine exerts a dual action on the amplitudeinterval relationship for simple test contractions elicited after a variable period of rest and preceding conditioning stimulation: (i) a flattening of the initial part of the “restitution” curve and (ii) a depression of the steady-state level reached after 2–10 s of rest. Raising [Ca2+] o elevates the steady state to control level but does not reestablish the initial slope of the curve. 5. Nifedipine, while leaving resting potential, maximum rate of depolarization and overshoot unaffected, tends to abbreviate the AP duration. Since this effect is more pronounced at lower frequencies, the usual prolongation of the AP occurring at low stimulation rates is inhibited. The AP plateau is depressed, but this effect seems to be stronger at higher stimulation rates. 6. In isolated SA nodes nifedipine (3×10−7–1×10−6 M) decreases discharge rate by reducing both the rate of the slow diastolic depolarization and the maximal diastolic potential until intranodal conduction blocks occur. 7. It is concluded that the negative inotropic action of nifedipine results mainly from diminished transmembrane Ca supply, with a slight action on internal sites of cardiac e.-c. coupling.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00501261
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Inotropic and electrophysiological actions of verapamil and D 600 in mammalian myocardium (1975)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 290 (1975), S. 81-97 
    Details
    ISSN: 1432-1912
    Keywords: Verapamil ; D 600 ; Optical Isomers ; Cardiac Muscle ; Transmembrane Action Potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Excitability, maximum velocity of depolarization (MVD), conduction velocity, discharge rate and the duration of transmembrane action potentials as a function of frequency of stimulation were studied in isolated cardiac tissues exposed to the optical isomers of verapamil and D 600. 1. In isolated papillary muscles depression of the MVD and the conduction velocity depend on concentration (1–8 μg/ml) of (+)-verapamil and (+)-D 600. 2. (+)-Verapamil and (+)-D 600 (1–30 μg/ml) increase frequency-dependently the threshold intensity of electrical stimuli needed to elicit conducted action potentials. 3. (-)-Verapamil and (-)-D 600 are about one order of magnitude less effective than the corresponding (+)-isomers. 4. Both (+)- and (-)-isomers slightly prolong the transmembrane action potential at 90% repolarization level, particularly at low frequencies. In addition, the (-)-isomers induce a frequency-dependent depression of the plateau phase. 5. The results indicate that, at least in ventricular myocardium, the (+)-isomers of verapamil and D 600 have a quite specific inhibitory effect on the fast Na-inward current and, therefore, may contribute to some extent to the anti-dysrhythmic potency of the racemic drugs. 6. In isolated cat SA-nodes, both (+)- and (-)-isomers of verapamil and D 600 (0.2–1.0 μg/ml) reduce the discharge rate to the point of complete suppression of automaticity; different mechanisms are responsible for the effects. 7. The (-)-isomers (0.3–0.6 μg/ml) slightly reduce the slope of the slow diastolic depolarization, while causing a more effective depression of MVD and nodal conduction velocity until partial or complete nodal conduction blocks occur. 8. The (+)-isomers (1–2μg/ml) do not affect MVD or nodal conduction, but obviously shift the threshold voltage for the fast depolarization to less negative voltages. Cessation of automaticity occurs with a stable membrane potential and the ability to generate conducted action potentials by electrical stimulation persists.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00499991
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Structure-activity studies on nifedipine in isolated cardiac muscle (1979)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 310 (1979), S. 69-78 
    Details
    ISSN: 1432-1912
    Keywords: Nifedipine ; Cat papillary muscle ; Inotropic effects ; Structure-activity relationship ; Hansch analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. The effects on contractile activity of 2 series of nifedipine-derivatives were investigated in isolated, isotonically contracting cat papillary muscles. 2. For structure-activity studies the lipophilicity of all compounds was determined by means of reversed phase thin-layer chromatography. 3. Neither the ortho-NO2 group in a series of arylderivatives nor the methyl-esters in a series of esterderivatives were found to be essential for the typical effect of the nifedipine molecule on myocardial contractility. 4. Generally ortho-substituted derivatives induce a greater negative inotropic activity than meta-substituted derivatives. Para-substituted derivatives are the least active compounds. 5. In the group of ester-derivatives activity decreases when lipophilicity and/or volume of the substituent increases. 6. The quantitative analysis (Hansch analysis) revealed significant correlations between the negative inotropic effect and steric substituent parameters. Best correlations were obtained with: i) the minimum width, B 1 (ortho-substituted derivatives); ii) the van der Waals volume, V w (ester-substituted derivatives); iii) the experimentally or theoretically determined lipophilicity, R M or π, respectively (ester-derivatives). 7. It is concluded that-within a group of nifedipine derivatives-the negative inotropic effect depends mainly on steric and on lipophilic and/or steric substituent properties for aryl- and ester-derivatives, respectively. Electronic influences are not important for the biological activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00499876
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Inotropic and electrophysiological actions of verapamil and D600 in mammalian myocardium (1975)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 290 (1975), S. 49-68 
    Details
    ISSN: 1432-1912
    Keywords: Verapamil ; D 600 ; Cardiac Muscle ; Amplitude-Frequency Relation ; Staircase Phenomena
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A pattern analysis of inotropic actions was carried out on isotonically shortening cat papillary muscles exposed to (±)-verapamil and (±)-D 600 and compared to other Ca-antagonistic interventions. 1. (±)-Verapamil (1–5 μg/ml) leaves contraction amplitudes nearly unchanged at 6/min, whereas at 60/min more than 90% depression (5 μ/ml) occurs. (±)-D 600 is about twice as effective as (±)-verapamil. 2. An increase of [Ca2+]0 in the presence of (±)-verapamil or (±)-D 600 does not restitute the normal amplitude-frequency relationship. There is only a shift toward higher contraction amplitudes. 3. (±)-Verapamil and (±)-D 600 lead to typical biphasic inotropic transients after step changes of the driving rhythm. First a fast and (at higher frequencies) very pronounced negative staircase occurs, followed by a rather slowly developing positive staircase. 4. These drug effects contrast to the effects of lowering [Ca2+]0 or of adding Ni2+ or La3+, which all produce a rather uniform depression of contraction amplitudes at all frequencies and do not elicit staircase phenomena such as seen under the influence of (±)-verapamil or (±)-D 600. 5. In contrast to the action of Ni2+, La3+ or low [Ca2+]0, (±)-verapamil slows down the restitution kinetics of Ca-reavailability from internal stores as determined by the amplitude of test contractions elicited after various periods of rest. 6. Drug-induced changes in the time course of the transmembrane action potential as depending on frequency may partially but not fully explain the contractile phenomena. 7. Possible interpretations as to the sites where (±)-verapamil or (±)-D 600 interferes with cardiac excitation-contraction coupling are given by the aid of a multicompartment model. This model describes excitation-contraction coupling in terms of transmembrane and intracellular Ca-movements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00499989
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Evidence for late Precambrian plate tectonics in West Africa (1979)
    [s.l.] : Nature Publishing Group
    Nature 278 (1979), S. 223-227 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In the Gourma and Iforas regions (Mali) rifting occurred around 800–850 Myr ago along the eastern margin of the West African craton with a triple point in Mali, the Gourma being interpreted as an aulacogen. Oceanic closure around 600 Myr led to a collision between the passive continental ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/278223a0
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    A performance model for preplanned disk sorting (1978)
    Springer
    Computing 21 (1978), S. 17-35 
    Details
    ISSN: 1436-5057
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Description / Table of Contents: Zusammenfassung Der Ansatz, Strings, die zusammengemischt werden, auf Magnetplatten vorzuplanen, wird unter Leistungsgesichtspunkten untersucht. Konzepte für die interne Pufferzuordnung, für die Erzeugung der anfänglichen Strings durch ein internes Sortierverfahren, und für die Stringverteilung auf Magnetplatten werden ausgewertet. Ein Algorithmus beschreibt die Konstruktion von suboptimalen Mischbäumen, die planbare Mischbäume genannt werden. Ein Kostenmodell, das auf detaillierte Annahmen der Zuordnung vonk Eingabeplatten und der Planung einesr-Wege-Mischens beruht, wird für das exakte Vorplanen aufgestellt. Zeitbetrachtungen für Sortieren und Mischen, die Hardware-Eigenschaften von Magnetplatten einschließen, zeigen signifikante Zeitgewinne verglichen mit weitverbreiteten Sortier- und Mischverfahren.
    Notes: Abstract The idea of preplanning strings on disks which are merged together is investigated from a performance point of view. Schemes of internal buffer allocation, initial string creation by an internal sort, and string distribution on disks are evaluated. An algorithm is given for the construction of suboptimal merge trees called plannable merge trees. A cost model is presented for accurate preplanning which consists of detailed assumptions on disk allocation fork input disks andr-way merge planning. Timing considerations for sort and merge including hardware characteristics of moveable head disks show a significant gain of time compared to widely used sort/merge applications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02252192
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Tensile properties of an extruded polyethylene-melt (1978)
    Springer
    Rheologica acta 17 (1978), S. 28-32 
    Details
    ISSN: 1435-1528
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Zusammenfassung Experimente zum isothermen Schmelzspinnen wurden mit dem „Rheotens“ an einer extrudierten Polyäthylenschmelze durchgeführt. Messungen von Abzugskraft, Abzugsgeschwindigkeit und Querschnittsprofil des extrudierten Stranges bei variierenden Ausstößen führten zur Bestimmung der Dehnviskosität als Funktion von Dehngeschwindigkeit und Deformationszeit. Es konnte nachgewiesen werden, daß die Deformationszeit besser als die Dehngeschwindigkeit zur Charakterisierung der Dehnviskosität von extrudierten Schmelzen geeignet ist.
    Notes: Summary Isothermal continuous stretching experiments with a Rheotens apparatus were carried out on an extruded polyethylene melt. Measurements of the tensile force, the thread velocity and the thread profiles for various mass flow rates resulted in the determination of the elongational viscosity as a function of the strain rate and the deformation time. It was found that the deformation time is a more suitable general parameter than the strain rate for the characterization of the elongational viscosity of extruded polymer melts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01567861
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...