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  • 1
    ISSN: 1432-2013
    Keywords: Calcium channels ; Calcium-activated potassium current ; Patch-clamp technique ; Posterior pituitary
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of tetrandrine, a bis-benzyl-isoquinoline alkaloid, on voltage-gated Ca2+ currents (I Ca) and on Ca2+-activated K+ current (I K(Ca)) and channels in isolated nerve terminals of the rat neurohypophysis were investigated using patch-clamp techniques. The non-inactivating component of I Ca was inhibited by external tetrandrine in a voltage- and dose-dependent manner, with an IC50=10.1 μM. I K(Ca) was elicited by depolarizations when approximately 10 μM Ca2+ was present on the cytoplasmic side. Only externally applied tetrandrine, at 1 μM, decreased the amplitude of I K(Ca), whereas the fast inward Na+ current and transient outward K+ current were not affected. Tetrandrine, applied to the extracellular side of outside-out patches excised from the nerve terminals, induced frequent and short closures of single type II, maxi-Ca2+-activated K+channels. Tetrandrine decreased the channel-open probability, within bursts, with an IC50=0.21 μM. Kinetic analysis of the channel activity showed that the open-time constant decreased linearly with increasing tetrandrine concentrations (0.01–3 μM), giving an association rate constant of 8.8×108 M−1s−1, whereas the arithmetic mean closed time did not change, giving a dissociation rate constant of 136.6s−1. These results show that tetrandrine is a high-affinity blocker of the type II, maxi-Ca2+-activated K+ channel of the rat neurohypophysial terminals.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-7373
    Keywords: extraneuronal monoamine transporter ; glioma ; SarCNU ; xenograft
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A novel analogue of nitrosoureas, 2-chloroethyl-3-sarcosinamide-1-nitrosourea (SarCNU), has demonstrated increased anticancer effects in vitro and in vivo. Our previous work suggested that SarCNU enters cells via the extraneuronal monoamine transporter (EMT), that contributes to its enhanced cytotoxicity. In the present study, comparative activities of SarCNU and 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) were evaluated in an EMT positive human glioma xenograft model. Athymic nude mice implanted subcutaneously or intracranially with human glioma SHG-44, a cell line that has been confirmed EMT positive by using reverse-transcription polymerase chain reaction (RT-PCR) assay, were treated with SarCNU at an optimal dose of 167 mg/kg, or BCNU at 20 mg/kg or 30 mg/kg, q4d×3 intraperitoneally (i.p.). In 17 animals with subcutaneous tumor grafts treated with SarCNU, 9 animals became tumor free and 8 demonstrated tumor regression. While in the BCNU treated group, there were only 2 out of 10 mice in the 20 mg/kg group and 2 out of 7 in the 30 mg/kg group, which demonstrated some tumor regression. There were 4 drug related deaths in the BCNU (30 mg/kg) group, while there were no drug related deaths in the SarCNU group. In the intracranially implanted mice, the median survival time in the SarCNU group was more than 130 days, while in the BCNU treated group it was only 22 days which was similar to the control group (18 days). This is the first demonstration that SarCNU, in comparison to BCNU, has enhanced anticancer activity in an EMT positive human glioma xenograft model.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    International journal of theoretical physics 39 (2000), S. 2513-2522 
    ISSN: 1572-9575
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The classical picture of a pure gluon plasma is given and classical transportequations for gluons in the system are derived and compared with quantumequations for gluons and classical equations for quarks.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    International journal of theoretical physics 35 (1996), S. 2501-2505 
    ISSN: 1572-9575
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract This paper presents an extended gauge theory which can contain the Higgs mechanism, considering λφ4 field theory as an example. It can introduce interaction into different vacuum modular degeneracy states and break modular degeneracy. At the same time we can obtain both massless and massive vector bosons. According to the extended gauge theory, gauge transformations can be classified into two kinds: those with fixed parameter, called simply definite gauge transformations, which have a function of breaking modular degeneracy, and indefinite gauge transformations, which have a function of keeping phase degeneracy.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    International journal of theoretical physics 37 (1998), S. 2395-2401 
    ISSN: 1572-9575
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present a semiclassical approach to thetrapping problem of atoms in the Jaynes-Cummings model.We express detuning in two ways, first by consideringdetuning as the superposition of many harmonic waves, ther other by establishing a relationshipbetween detuning and the distribution of the momentum ofatoms. In these two cases we find the appearance oftrapping atoms; we discuss the quantum chaotic movement of atoms irradiated with a stronglaser.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    The journal of Fourier analysis and applications 2 (1995), S. 507-517 
    ISSN: 1531-5851
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract The Cauchy problem and global well-posedness for a mathematical model of the strong interaction of two-dimensional, long, internal gravity waves propogating on neighboring pycnoclines in a stratified fluid have been studied by Bona, Ponce, Saut, Tom, and others. We show that global well-posedness occurs even when the initial data is rough.
    Type of Medium: Electronic Resource
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