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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Macromolecules 27 (1994), S. 6571-6576 
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 117-118 (Jan. 1993), p. 351-356 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 312-314 (July 1999), p. 109-114 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 312-314 (July 1999), p. 159-166 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 136 (2000), S. 291-302 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Hypoxia/anoxia in coastal waters is a world wide problem which often results in mass mortality and defaunation of benthos. In this study, field experiments were carried out to examine recolonization and succession of macrobenthic infauna in defaunated sediments, and the time required for recovery from complete defaunation to a stable community. Trays (33 cm length × 25.5 cm width × 11 cm depth) of defaunated sediment were exposed at the subtidal of a pristine site in subtropical Hong Kong. Temporal changes of macrobenthic communities in defaunated sediment were analyzed by univariate and multivariate statistics, and compared with those in undisturbed natural sediment at the same site. Initial colonization of macrobenthos occurred rapidly. A total of 42 species was found, with an average of 258 animals per tray and 24 species per tray recorded in the first month. Abundance showed a small peak (496 animals per tray) after 3 months, reached a sharp peak (1154 animals per tray) after 6 months, and declined thereafter. Species number increased gradually, reached a maximum (68 species per tray) after 9 months, and then decreased. Recolonization was predominantly contributed by larval settlement rather than adult migration. Temporal changes in abundance, species number and diversity of the macrobenthic community in defaunated sediment resemble the spatial changes along a decreasing pollution gradient previously defined by other authors. Results of this experiment suggest that newly available sediment may allow more species to colonize (or coexist) than sediment pre-occupied by an established community. This is probably due to less interspecific competition in the former habitat. No significant difference in abundance or species richness was observed between defaunated and natural sediments after 15 months, suggesting that a stable community had been achieved, although minor variations in species composition were still discernible between defaunated and natural sediments.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    The journal of membrane biology 149 (1996), S. 33-40 
    ISSN: 1432-1424
    Keywords: Key words: Chlorotrifluoroethylene — GABA receptor — Voltage clamp — Chloride current —Xenopus oocyte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract. GABA-activated Cl− current was expressed in Xenopus oocytes after injecting cRNA that had been transcribed in vitro from complementary DNA (cDNA) coding for a single GABA ρi-subunit cloned from human retina. The expressed current was insensitive to 100 μm bicuculline, but was activated by the GABA analogue trans-4-aminocrontonic acid (TACA). Anion-selective permeability of the expressed ρ1-subunit was determined by isotonically replacing the extracellular Cl− with different anions. The anion permeability was very similar to the native GABAA receptor/channel following a sequence of SCN− 〉 I− 〉 NO3 − 〉 Br−≥ Cl−. Halogenated fatty acids, such as chlorotrifluoroethylene (CTFE) and perfluorinated oligomer acids inhibited the GABA-induced current in oocytes expressing the human retinal GABA ρ1-subunit or rat brain GABAA receptor α1,β2,γ2 subunits. The inhibitory effect of halogenated fatty acids demonstrated a carbon chain length-dependent manner of: C10 〉 C8 〉 C6 〉 C4. Perfluorinated C8-oligomer acid (PFOA) was less effective at blocking this channel than the C8-CTFE oligomer acid. Radiolabeled GABA binding assay indicated that CTFE oligomer acids do not interfere at the GABA binding site of the receptor. Furthermore, the C8-CTFE oligomer fatty acid did not compete with picrotoxin for binding sites within the pore of the channel. These studies demonstrated that the heterologous expression system is useful for studying the molecular interaction between potential neurotoxic agents and neuroreceptors. Our results provide detailed information that should contribute to our understanding of the structure and function of retinal GABA receptors.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    The journal of membrane biology 172 (1999), S. 113-120 
    ISSN: 1432-1424
    Keywords: Key words: Apoptosis — 4-Aminopyridine — High K+ concentration — Gene expression — Membrane potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract. Mcl-1, a member of the Bcl-2 family, has been identified as an inhibitor of apoptosis induced by anticancer agents and radiation in myeloblastic leukemia cells. The molecular mechanism underlying this phenomenon, however, is not yet understood. In the present study, we report that hyperpolarization of the membrane potential is required for prevention of mcl-1 mediated cell death in murine myeloblastic FDC-P1 cells. In cells transfected with mcl-1, the membrane potential, measured by the whole-cell patch clamp, was hyperpolarized more than −30 mV compared with control cells. The membrane potential was repolarized by increased extracellular K+ concentration (56 mV per 10-fold change in K+ concentration). Using the cell-attached patch-clamp technique, K+ channel activity was 1.7 times higher in mcl-1 transfected cells (NP o = 22.7 ± 3.3%) than control cells (NP o = 13.2 ± 1.9%). Viabilities of control and mcl-1 transfected cells after treatment with the cytotoxin etoposide (20 μg/ml), were 37.9 ± 3.9% and 78.2 ± 2.0%, respectively. Suppression of K+ channel activity by 4-aminopyridine (4-AP) before etoposide treatment significantly reduced the viability of mcl-1 transfected cells to 49.0 ± 4.6%. These results indicate that as part of the prevention of cell death, mcl-1 causes a hyperpolarization of membrane potential through activation of K+ channel activity.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    The journal of membrane biology 142 (1994), S. 65-75 
    ISSN: 1432-1424
    Keywords: Patch clamp ; Chloride channel ; cAMP-dependent protein kinase ; Human hematopoietic myeloblast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Using the inside-out patch clamp technique, we identified a Cl− channel in patches from the membrane of cultured human hematopoietic myeloblastic leukemia ML-1 cells. The Cl− channel was not seen at negative membrane potentials in excised patches until the membrane potential was depolarized to greater than +40 mV. The channel was also activated by addition of cAMP-dependent protein kinase (PKA) catalytic subunit at physiological membrane potential (−40 mV). Biophysical studies of the Cl− channel revealed that the current-voltage (I-V) relationship of the Cl− channel was outwardly rectifying in symmetrical 142 mm Cl− solutions. Single channel conductances were 48 pS for the outward current measured at +60 mV and 27 pS for the inward current at −60 mV. The open time constant of the channel was dependent on the membrane potential and was significantly prolonged at positive membrane potentials. Channels activated by cAMP-dependent protein kinase spent a significantly longer time in the open state compared to those channels activated by depolarization pulses. Pharmacological properties of the Cl− channel were also studied. Two anion transport inhibitors, anthracene-9-carboxylic acid (9-AC) and 4,4-diisothiocyanatostilbene-2,2-disulfonic acid (DIDS) caused a flickering block of the channel. Half-inhibitory concentrations (IC50) for 9-AC and DIDS were 174 ± 20 and 70±16 μm, respectively. Blockade of the Cl− channel by 9-AC or DIDS was completely reversible. Our findings suggest that outwardly rectifying Cl− channels (ORCC) are present in human hematopoietic myeloblasts. The function of ORCC may be involved in hormone-regulated cell growth, cell volume regulation and immune responses.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    The journal of membrane biology 164 (1998), S. 115-124 
    ISSN: 1432-1424
    Keywords: Key words: Receptor/channel — Retinal ρ1-subunit — Chimera — Voltage-clamp — Barbiturates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract. Desensitization of ligand-gated receptor channels is an intrinsic feedback mechanism and prevents the receptor/channels from becoming overly activated thereby maintaining biological function of the nervous system. Desensitization also plays an important role in neuronal plasticity. By taking advantage of biophysical and pharmacological diversities of GABA β2 subunits from the brain and ρ1 subunits from the retina, structural determinants that confer agonist-induced desensitization were identified. A synthetic chimeric receptor/channel was created from the β2 and ρ1 subunits for this investigation. The chimera was constructed from the extracellular N-domain of the β2 subunit, extending from the amino terminus to the beginning region of the M1 transmembrane segment, and from the C-domain of the ρ1 subunit extending from the M1 transmembrane segment to the carboxyl terminus. The C-domain region included the M1 to M4 transmembrane regions and the large intracellular loop between the M3 and M4 transmembrane segments. Homo-oligomeric GABA β2, ρ1, and β2/ρ1 chimeric receptor/channels were individually expressed in Xenopus oocytes, and the desensitization characteristics attributable to each type of subunit were compared. Results from the present study reveal that motifs in the amino-terminal and carboxyl-terminal domains of the β2 subunit conferred the agonist-induced desensitization; chloroform modulation was linked to specific phases of the GABA-activated current decay.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Journal of metastable and nanocrystalline materials Vol. 15-16 (Apr. 2003), p. 649-654 
    ISSN: 1422-6375
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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