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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 111 (1989), S. 6828-6833 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Solid state phenomena Vol. 135 (Feb. 2008), p. 131-134 
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Notes: The microstructure and mechanical properties of Ti joints brazed with aZr41.2Ti13.8Ni10.0Cu12.5Be22.5 (at.%) amorphous filler were investigated. With a Zr-based amorphousfiller, in this study, Ti joints with a homogeneous composition could be obtained by heating to wellbelow the α-β transformation temperature for a short time, so that the undesirable effects of the hightemperature heating are considerably diminished. The joints brazed at 790 °C for 10 min consisted ofthe coarse acicular structure rather than the fine Widmanstätten structure which generally deterioratesthe ductility of the joints. The joints with the homogenous coarse acicular structure, i.e. without aresidual liquid region, show almost the same mechanical properties as those required for base metalswithout heating. Although the residual liquid region in the joints deteriorates the ductility of the joints,this region could be successfully removed by a diminution in the quantity of the filler
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 41 (1963), S. 628-633 
    ISSN: 1432-1440
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Zusammenfassung Die Bestimmung der HWZ von Fettpartikeln im Blut mit Hilfe intravenös injizierter radioaktiv markierter Fettemulsionen wird beschrieben. Es wird diskutiert, wieweit ein darauf aufbauender Test Einblick in den Chylomikronenstoffwechsel geben kann. Die Brauchbarkeit des Testes wird an größeren Personengruppen geprüft. Bei normolipämischen Personen beträgt die HWZ 3,74±0,69 min. Bei Hyperlipämien lassen sich zwei Formen trennen. Mögliche Gründe für die Verlängerung der HWZ bei Hyperlipämien werden diskutiert.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1424
    Keywords: Noninactivating cardiac Na+ channels ; Removal of inactivation ; Cardiac Na+ channel protein ; α-subunit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Elementary Na+ currents were recorded in inside-out patches from neonatal rat heart cardiocytes to analyze the influence of a site-directed polyclonal anti-serum against the linker region between the domains III and IV (amino acids 1489–1507 of the cardiac Na+ channel protein) on Na+ channel gating and to test whether this part of the α-subunit may be considered as a target for modifying agents such as the (−)-enantiomer of DPI 201-106. Anti-SLP 1 serum (directed against amino acids 1490–1507) evoked, usually within 10–15 min after cytosolic administration, modified Na+ channel activity. Antiserum-modified Na+ channels retain a single open state but leave, at −60 mV for example, their conducting configuration consistently with an about threefold lower rate than normal Na+ channels. Another outstanding property of noninactivating Na+ channels, enhanced burst activity, may be quite individually pronounced, a surprising result which is difficult to interpret in terms of structure function relations. Removal of inactivation led to an increase of reconstructed peak I Na (indicating a rise in NP o) and changed I Na decay to obey second-order kinetics, i.e., open probability declined slowly but progressively during membrane depolarization. The underlying deactivation process is voltage dependent and responds to a positive voltage shift with a deceleration but may operate even at the same membrane potential with different rates. Iodatemodified Na+ channels exhibit very similar properties including a conserved conductance. They are likewise controlled by an efficient, voltage-dependent deactivation process. Modification by (−)-DPI 201-106 fundamentally contrasts to the influence of anti-SLP 1 serum and the protein reagent iodate since (−)-DPI-modified Na+ channels maintain their open probability for at least 120 msec, i.e., a deactivation process seems lacking. This functional difference suggests that the linker region between the domains III and IV of the α-subunit may not be the only target for (−)-DPI 201-106 and related compounds, if at all.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1084
    Keywords: Key words: Liver neoplasms ; Surgery ; Echinococcosis ; Focal nodular hyperplasia ; Hemangioma ; US ; CT
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The purpose of our work was to provide data on the recurrence of resected benign hepatic lesions and to evaluate the value of follow-up examinations in this group of patients. From August to October 1993, 75 patients who had been admitted for liver surgery for benign tumors between 1975 and 1993 were controlled by physical examinations, serological tests, US, and, in the case of equivocal US findings, by CT. The histological diagnoses of the operative specimen included hydatidosis in 43 patients, focal nodular hyperplasia (FNH) in 12 patients, liver cell adenoma in 8 patients, cavernous hemangioma in 8 patients, and congenital cyst in 4 patients. Hepatic scars were observed in 36 of the 75 patients. Four cases of intrahepatic recurrence and 1 case of intraperitoneal spread were observed in the 42 patients with recent hydatosis. Long-term postoperative controls (specific serological tests, US) are necessary in the management of patients with hydatid disease. Follow-up examinations are not indicated in asymptomatic patients who have been operated on for FNH, hemangioma, or congenital cysts.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    European biophysics journal 9 (1983), S. 181-191 
    ISSN: 1432-1017
    Keywords: Alamethicin pore ; Voltage-dependent conductance ; α-helical structure ; Dipole moment ; Lipid bilayers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract The voltage-dependency of alamethicin pore formation is explained by a flip-flop gating mechanism of single alamethicin molecules. The energetically preferred aggregate structure is changed from antiparallel to parallel molecule orientation by membrane voltage application. The electrical field is sensed by the permanent dipole of the α-helical molecule part which spans the hydrophobic membrane core. Ion conducting pore and pore states result from electrostatic repulsion of a varying number of parallel dipoles which arrange circularly. This model is consistent with published data and with two additional experimental facts, that pore state distributions are ionic strength dependent and pore state conductances depend on ionic current direction.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    European biophysics journal 12 (1985), S. 67-73 
    ISSN: 1432-1017
    Keywords: Aggregation ; dielectric dispersion ; dipole moment ; molecular shape ; pore former
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract The peptides Boc-(l-Ala-Aib-l-Ala-Aib-l-Ala)n-OMe, with n=2 (P10) and n=4 (P20), have been synthesized as purely hydrophobic models of the antibiotic alamethicin, which is known to be a voltage-dependent pore former in membranes and is apparently α-helical in lipophilic media. These peptides were investigated in 1-octanol, a solvent which resembles the membrane environment. From dielectric dispersion studies quantitative information on the molecular shape and dipole moments could be derived. Further independent data concerning conformation and extent of aggregation of the peptides were obtained by circular dichroism and ultracentrifuge measurements. The results suggest that the peptides assume the form of elongated particles having a significant amount of ordered secondary structure and carrying a dipole parallel to the long axis. Apparently the monomeric peptide molecules undergo, to some extent, a head-to-tail aggregation which is slightly enhanced at lower temperatures. Based on the high-frequency parts of the dielectric dispersion curves the lengths, diameters, and dipole moments of the monomer particles have been determined as 22.5 Å, 10 Å, 36 D (P10) and 28.5 Å, 12 Å, 64 D (P20).
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-1017
    Keywords: Key words Single cardiac Na+ channels ; Site-directed antipeptide antibody ; Proteolysis ; Protein reagents ; Calpain ; Stochastic mode switching
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Failure of inactivation is the typical response of voltage-gated Na+ channels to the cytosolic presence of proteolytic enzymes, protein reagents such as N-bromoacetamide (NBA) or iodate, and antibodies directed against the linker between domains III and IV of the α-subunit. The present patch clamp experiments with cardiac Na+ channels aimed to test the hypothesis that these interventions may provoke the occurrence of non-inactivating Na+ channels with distinct kinetic properties. A site-directed polyclonal antibody (anti-SLP2, target sequence 1481–1496 of the cardiac Na+ channel α-subunit) eliminated fast Na+ inactivation to induce burst activity which was accompanied by the occurrence of two open states. A deactivation process terminated channel activity during membrane depolarization proceeding with time constants of close to 40 ms (at –40 mV). NBA-modified and iodate-modified Na+ channels were kinetically indistinguishable from the anti-SLP2-modified type since they likewise deactivate and, thus, attain an only moderate Po of close to 20%. This is fundamentally different from the behaviour of enzymatically-modified Na+ channels: after cytosolic proteolysis with α-chymotrypsin, trypsin or pronase, mean Po during membrane depolarization amounted to approximately 40% because deactivation operated extremely slowly and less efficiently (time constants 100–200 ms at –40 mV, as a minimum) or was virtually non-operating. In-vitro cleavage of the synthetic linker sequence 1481–1496 confirmed that this part of the α-subunit provides a substrate for these peptidases or reactants for NBA but cannot be chemically modified by iodate. This iodate resistance indicates that iodate-modified Na+ channels are based on a structural alteration of still another region which is also involved in Na+ inactivation, besides the linker between domains III and IV of the α-subunit. Endogenous peptidases such as calpain did not affect Na+ inactivation. This stresses the stochastic nature of a kinetic peculiarity of cardiac Na+ channels, mode-switching to a non-inactivating mode.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-1017
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    European biophysics journal 23 (1994), S. 155-165 
    ISSN: 1432-1017
    Keywords: Alamethicin ; Ion channel blockade ; Planar lipid bilayers ; Polycations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract The effects of the peptide polycations salmon protamine (M r = 4332,z = + 21) and poly-l-lysine (M r ≅ 100,00,z ≅ + 775) on ion channels formed by synthetic alamethicin Alm-F30 (one negative charge), natural Alm-F50 (neutral) and phosphorylated Alm-F50 (two negative charges) reconstituted in planar lipid bilayers have been studied at the single channel level. It was observed that both polycations in micromolar concentrations transiently block ion permeation through the channels formed by each alamethicin analogue, although in case of the neutral Alm-F50 to a significantly lesser extent. Poly-l-lysine showed to be more effective than protamine in blocking these channels. If either polycation is present in the cis-compartment, blockade occurs only at cis positive membrane voltages. At constant polycation concentration, dwell times in the blocked state increase when salt concentration is lowered, and decrease at acidic pH with an apparent pK of 4.8. Mean lifetime of blockade events shortens when membrane voltage is increased, which suggests that both polycations may permeate through the oligomeric alamethicin channels if conductance levels are 〉 2. We suggest that blockade is caused by electrostatic binding of a single polycation molecule to the C-terminal channel mouth; in case of Alm-F30, Glu18 has to be considered as the putative binding site. Our results provide further evidence for the barrel-stave model and a parallel orientation of dipole monomers in the channel aggregate, the C-termini facing the membrane side with the more positive membrane potential.
    Type of Medium: Electronic Resource
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