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  • Articles: DFG German National Licenses  (14)
  • 1995-1999  (14)
  • 1990-1994
  • 1998  (14)
  • 1
    Electronic Resource
    Electronic Resource
    Patch-Clamp Analysis of the Mechanism of PACAP-Induced Excitation in Rat Supraoptic Neurones (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neuroendocrinology 10 (1998), S. 0 
    Details
    ISSN: 1365-2826
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In neurosecretory cells of the supraoptic nucleus (SON) of rats, pituitary adenylate cyclase activating polypeptide (PACAP)causes an increase in [Ca2+]i, and stimulates somatodendritic vasopressin (VP) release. In this report, to elucidate the ionic mechanism of the action of PACAP, membrane potentials and ionic currents were measured from SON neurones in slice preparations or from dissociated SON neurones. In the current clamp mode, PACAP depolarized membrane potentials of both phasic and non-phasic neurones and increased the firing rate. Moreover, simultaneous measurements of membrane potentials and [Ca2+]i revealed that the membrane depolarization correlated well with increases in [Ca2+]i. In the voltage-clamp mode, PACAP induced inward currents at a holding potential of −70 or −80 mV in a dose-dependent manner and the time course of the currents was similar to that of the PACAP-induced membrane depolarization. The averaged reversal potential of the PACAP-induced currents obtained from dissociated SON neurones was −33 mV, which was close to the reversal potential of non-selective cation currents in SON neurones. The currents were rapidly and reversibly inhibited by a cation-channel blocker, gadolinium. Analysis of synaptic inputs into SON neurones in slice preparations revealed that PACAP had little or no effects on the frequency of spontaneous excitatory and inhibitory postsynaptic currents. These results suggest that pituitary adenylate cyclase activating polypeptide (PACAP) activates PACAPreceptors in the postsynaptic membrane of the supraoptic nucleus (SON) neurones, and that the activation of PACAP receptors leads to opening of non-selective cation channels, depolarization of the membrane potential, and increase in the firing rate in SON neurones. Such mechanisms may account for the PACAP-induced increase in [Ca2+]i and vasopressin (VP) release observed in SON neurones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2826.1998.00260.x
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  • 2
    Electronic Resource
    Electronic Resource
    ESTIMATION OF TORSIONAL FATIGUE STRENGTH OF MEDIUM CARBON STEEL BARS WITH A CIRCUMFERENTIAL CRACK BY THE CYCLIC RESISTANCE-CURVE METHOD (1998)
    Oxford, UK : Blackwell Science Ltd
    Fatigue & fracture of engineering materials & structures 21 (1998), S. 0 
    Details
    ISSN: 1460-2695
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Near-threshold fatigue crack propagation tests were performed on circumferentially precracked round bars of a medium carbon steel under torsional loading. The crack propagation rate decreased with crack extension, because of the shear contact of crack faces. The crack propagation rate without the influence of crack-surface contact was determined by extrapolating to zero crack extension the relationship between the crack propagation rate and crack extension. The applied stress intensity factor range was divided into two parts: one was the effective value responsible for crack growth and the other was the value corresponding to crack-tip shielding. The resistance-curve method was used to predict the fatigue limit for crack initiation and fracture. The R-curve was constructed using the experimentally determined threshold value of the stress intensity range, which was the sum of the threshold effective stress intensity range and the threshold shielding stress intensity range. The threshold effective stress intensity range was constant. The R-curve was independent of the precrack length and specimen dimensions. The predicted values agreed well with the experimental results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-2695.1998.00105.x
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  • 3
    Electronic Resource
    Electronic Resource
    Endogenous protease-dependent replication of human influenza viruses in two MDCK cell lines (1998)
    Springer
    Archives of virology 143 (1998), S. 1893-1909 
    Details
    ISSN: 1432-8798
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary.  Multi-cycle replication and plaque formation of influenza A and B viruses and cleavage activation of their hemagglutinin (HA) by an endogenous protease(s) were examined in two MDCK cell lines, MDCK(−) and MDCK(+). No exogenous trypsin was required for multi-cycle replication and plaque formation of all the influenza A viruses tested in the MDCK(+) cell, while those of the viruses in the MDCK(−) cell were completely trypsin-dependent. In both cell lines, on the other hand, influenza B viruses grew well in the absence of trypsin. The capability of multiple replication and plaque formation of the influenza viruses correlated with cleavage of the HA precursor (HA0) to HA1 and HA2, indicating that both cell lines express an HA activating endoprotease(s); that of the MDCK(+) cell activates the HA of influenza A and B viruses, and that of the MDCK(−) cell does only the HA of influenza B virus. Furthermore, the protease of the MDCK(+) cell was strongly suggested to be present on the cell surface and a serine protease. The MDCK(+) cell would be useful for isolation of influenza viruses from clinical specimens and for screening of protease inhibitors for anti-influenza virus drugs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007050050428
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  • 4
    Electronic Resource
    Electronic Resource
    Amplification of JC virus regulatory DNA sequences from cerebrospinal fluid: diagnostic value for progressive multifocal leukoencephalopathy (1998)
    Springer
    Archives of virology 143 (1998), S. 249-262 
    Details
    ISSN: 1432-8798
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary.  Progressive multifocal leukoencephalopathy (PML) is a fatal demyelinating disease in the central nervous system caused by a ubiquitous human polyomavirus designated as JC virus (JCV). PML affects individuals with decreased immune competence and is now one of the common opportunistic infections in patients with AIDS. JCV DNAs in the brain of PML patients contain various PML-type regulatory regions that were generated from the archetypal regulatory region during persistence. Recently, many studies have suggested that detection of JCV DNA from the cerebrospinal fluid (CSF) may offer a tool for diagnosing PML. However, in all of these studies, coding sequences within the T antigen or capsid protein gene have been targeted for amplification. To amplify the JCV regulatory region, we established a nested PCR that could efficiently amplify the regulatory region from most JCV subtypes prevalent in the world. Using this PCR, we amplified JCV regulatory regions from the CSF samples from 4 patients strongly suspected of PML, whereas amplification was negative from 80 CSF samples from patients without PML. Sequencing of the amplified fragments revealed that they had unique deletions and/or duplications. Furthermore, in 3 PML patients, we analyzed the structures of regulatory regions derived from the brain as well as CSF. In each of these cases, the major regulatory sequence of both origins were identical. This finding indicates that JCV DNA in brain lesions is excreted in the CSF. Since the structures of PML-type JCV regulatory regions are unique to individual patients, the current PCR, if the amplified fragments are sequenced, can eliminate false positives that may arise from contaminations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007050050284
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Pump and probe X-ray absorption fine structure using high-brilliance photon sources (1998)
    Chester : International Union of Crystallography (IUCr)
    Journal of synchrotron radiation 5 (1998), S. 1001-1003 
    Details
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Pump and probe X-ray absorption fine structure (XAFS) is used as a local probe of excited atoms, which can provide direct information on lattice distortion, relaxation and atomic rearrangements associated with electronic excitations. In situ XAFS experiments during optical excitation are reported. Utilizing a grazing-incidence fluorescence excitation, which minimizes the mismatch between the probing depths of X-ray excitation and optical pumping, it is found that the dominant photoinduced defect state in amorphous selenium at low temperature is a pair of threefold neutral C^0_3 states: 2C^*_2 \rightarrow (C^0_3-C^0_3), where C^*_2 denotes the twofold excited lone-pair state. The results indicate that optical pumping of chalcogen atoms at low temperature leads to locally over-coordinated defect pairs similar to those in the liquid state. The origin of reversible photostructural changes, such as photodarkening or photoinduced fluidity, is attributed to the structural disorder caused by the formation and annihilation of dynamical interchain bonds during optical melting.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0909049597014301
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Nanoscale mechanism of photoinduced metastability and reversible photodarkening in chalcogenide vitreous semiconductors (1998)
    Springer
    Semiconductors 32 (1998), S. 801-806 
    Details
    ISSN: 1063-7826
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The present paper reviews the results oblained by the authors in the last three years. By applying in-situ (pamp and probe) EXAFS to reversible photostructural changes in chalcogenide vitreous semiconductors we have found an increase in the average coordination number of selenium species in the photoexcited state which comes from the formation of dynamic interchain bonds. Subsequent bond rupture, studied by optically induced ESR, results in the formation of over-and undercoordinated ESR-active defects, which are further transformed into charged valence-alternation pairs. Annealing close to the glass-transition temperature results in recovery of the initial structure. Relationship between the detected structural changes and photodarkening is also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.1187510
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  • 7
    Electronic Resource
    Electronic Resource
    Transport properties of microcrystalline silicon at low temperatures (1998)
    Springer
    Semiconductors 32 (1998), S. 807-811 
    Details
    ISSN: 1063-7826
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The dark conductivity and photoconductivity along with pulsed electron spin resonance have been measured over a wide temperature range with a high crystallinity hydrogenated microcrystalline silicon (μc-Si: H) sample. The transport mechanism in μc-Si: H is discussed on the basis of these measurements. Striking similarities in the temperature dependences of the dark conductivity and photoconductivity between μc-Si: H and some well-studied materials, such as hydrogenated amorphous silicon, suggest that at low temperatures hopping of carriers between localized states dominates the transport properties of μc-Si: H.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.1187511
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    A novel glycoprotein obtained from Chlorella vulgaris strain CK22 shows antimetastatic immunopotentiation (1998)
    Springer
    Cancer immunology immunotherapy 45 (1998), S. 313-320 
    Details
    ISSN: 1432-0851
    Keywords: Key words Chlorella vulgaris ; MethA ; Metsatasis ; Antitumor immunity ; CD4 T cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  A glycoprotein extract (CVS), derived from the unicellular green alga Chlorella vulgaris, strain CK22, exhibited a pronounced antitumor effect against both spontaneous and experimentally induced metastasis in mice. Inhibition of tumor metastasis was enhanced when intratumor administration of CVS was followed by s.c. injection of CVS. Anti-metastatic immunopotentiation was observed in euthymic mice, but not in athymic nude mice. The antitumor activity of CVS was reflected in antigen-specific, T-cell-mediated immunity. Both CD4 and CD8 T cells contributed to the antimetastatic effects, as shown by in vivo depletion experiments with anti-T-cell subset antibodies. Furthermore, CVS caused the recruitment of T cells to the regional lymph nodes and their proliferation in these organs. The CD4-positive population, following CVS injection at the time of tumor rechallenge, displayed a pronounced increase in the proportion of T cells that were CD18 bright, CD44 bright, CD25+, CD54+, CD69+ or CD71+ in the lymph nodes. Thus, CVS induces T cell activation in peripheral lymph nodes in tumor-bearing mice. We conclude that CVS augments antimetastatic immunity through T cell activation in lymphoid organs and enhances recruitment of these cells to the tumor sites. Presurgical treatment with CVS might prevent metastasis or tumor progression.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002620050448
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  • 9
    Electronic Resource
    Electronic Resource
    Prostaglandin E2 (PGE2) Autoamplifies its Production Through EP1 Subtype of PGE Receptor in Mouse Osteoblastic MC3T3-E1 Cells (1998)
    Springer
    Calcified tissue international 62 (1998), S. 327-331 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Prostaglandin E2— Prostaglandin E receptor — MC3T3-E1 cells — Osteoblast — Prostaglandin G/H synthase-2.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. Prostaglandin E2 (PGE2) is known to autoamplify its production in the osteoblasts through the induction of prostaglandin G/H synthase-2 (PGHS-2), which is the inducible form of the rate-limiting enzyme in PG synthesis, PGHS. To elucidate the cellular mechanism mediating this process, we have employed the PGE2 analogs, which are specific agonists for four subtypes of PGE receptor, and studied the potency of these analogs to induce PGHS-2 mRNA in mouse osteoblastic MC3T3-E1 cells. The induction was mainly observed by 17-phenyl-ω-trinor PGE2 (EP1 agonist) and sulprostone (EP3/EP1 agonist), but not by butaprost (EP2 agonist) or 11-deoxy PGE1 (EP4/EP2 agonist). Since EP3 subtype was undetectable in MC3T3-E1 cells, these data indicate that PGHS-2 mRNA induction is mediated through EP1 subtype of PGE receptor in MC3T3-E1 cells. PGE2 production determined by radioimmunoassay was also increased by 17-phenyl-ω-trinor PGE2 and sulprostone. The autoamplification of PGE2 production is considered to be important in elongating the otherwise short-lived PGE2 action in certain physiological conditions such as mechanical stress and fracture healing, as well as the pathological inflammatory bone loss. The observations in the present study provide us with the better understanding of these processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900440
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  • 10
    Electronic Resource
    Electronic Resource
    Photoinduced structural changes in amorphous semiconductors (1998)
    Springer
    Semiconductors 32 (1998), S. 861-866 
    Details
    ISSN: 1063-7826
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract A variety of photostructural changes observed in tetrahedral and chalcogenide amorphous semiconductors are reviewed from physical and chemical points of view. In particular, observations of the photodarkening and related phenomena in chalcogenide glasses are summarized, and structural models which have been proposed so far are criticized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1134/1.1187473
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