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  • 1
    Electronic Resource
    Electronic Resource
    Lithium inhibits caspase 3 activation and dephosphorylation of PKB and GSK3 induced by K+ deprivation in cerebellar granule cells (2001)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 78 (2001), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Lithium protects cerebellar granule cells from apoptosis induced by low potassium, and also from other apoptotic stimuli. However, the precise mechanism by which this occurs is not understood. When cerebellar granule cells were switched to low potassium medium, the activation of caspase 3 was detected within 6 h, suggesting a role of caspase 3 in mediating apoptosis under conditions of low potassium. In the same conditions, lithium (5 mm) inhibited the activation of caspase 3 induced by low potassium. As lithium did not inhibit caspase 3 activity in vitro, these results suggest that this ion inhibits an upstream component that is required for caspase 3 activation. Lithium is known to inhibit a kinase termed glycogen sythase kinase 3 (GSK3), which is implicated in the survival pathway of phosphatidylinositol 3-kinase/protein kinase B (PI3K/PKB). Here we demonstrate that low potassium in the absence of lithium induces the dephosphorylation, and therefore the activation, of GSK3. However, when lithium was present, GSK3 remained phosphorylated at the same level as observed under conditions of high potassium. Low potassium induced the dephosphorylation and inactivation of PKB, whereas when lithium was present PKB was not dephosphorylated. Our results allow us to propose a new hypothesis about the action mechanism of lithium, this ion could inhibit a serine-threonine phosphatase induced by potassium deprivation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2001.00410.x
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  • 2
    Electronic Resource
    Electronic Resource
    Atenolol improves ventricular function without changing plasma noradrenaline but decreasing plasma atrial natriuretic factor in chronic heart failure (2002)
    Oxford, UK : Blackwell Science Ltd
    Autonomic & autacoid pharmacology 22 (2002), S. 0 
    Details
    ISSN: 1474-8673
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Chemistry and Pharmacology , Medicine
    Notes: 1 There is good evidence that β-blockers improve ventricular function, disease progression and survival in patients with left ventricular systolic dysfunction. The aim of this study was to determine the effects of atenolol therapy on the sympathetic nervous system at rest and after ergometric exercise, on left ventricular function and on baseline plasma atrial natriuretic factor (ANF) in ambulatory patients with chronic heart failure (CHF). 2 Twenty-two patients [left ventricular ejection fraction (LVEF) 〈36%; New York Heart Association II–III] were studied before atenolol treatment. Because of cardiac events (new Hospital admission or death) only 13 patients completed 1 year of treatment. Baseline noradrenaline (NE) concentrations were similar in patients and controls while ANF was higher in patients than in controls (328 ± 35 pg ml−1vs. 37 ± 3 pg ml−1; P 〈 0.01). 3 Patients with events showed higher NE (540 ± 87 pg ml−1vs. 303 ± 44 pg ml−1; P 〈 0.01) and ANF (460 ± 70 pg ml−1vs. 291 ± 44 pg ml−1; P 〈 0.03) at rest; and greater NE response to exercise (2.003 ± 525 pg ml−1vs. 694 ± 121 pg ml−1; P 〈 0.005). Atenolol treatment improved LVEF (19.5 ± 1.9%vs. 33 ± 3.9%; P 〈 0.001), increased exercise tolerance (9 ± 3.2 min vs. 17 ± 4.8 min; P 〈 0.001) and decreased plasma ANF (292 ± 42 pg ml−1vs. 133 ± 35 pg ml−1; P 〈 0.01). 4 Reduced basal dihydroxyphenylglycol (DHPG)/NE ratio (3.4 ± 0.46 vs. 4.3 ± 0.35; P 〈 0.01) was observed in patients compared with healthy volunteers. Atenolol increased DHPG plasma levels (1.398 ± 129 pg ml−1vs. 913 ± 86 pg ml−1; P 〈 0.005) but the DHPG/NE ratio during exercise was not modified after treatment, suggesting that re-uptake of released NE is not changed by β-blocker treatment. 5 In conclusion, the fact that atenolol treatment improves ventricular dysfunction and clinical status without changing plasma NE levels in CHF patients, suggests that plasma NE is a poor surrogate measurement for cardiac sympathetic activity in this pathology. In addition, decrease in plasma ANF produced by atenolol treatment may reflect the improvement of ventricular function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1474-8673.2002.00266.x
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  • 3
    Electronic Resource
    Electronic Resource
    The neurotrophic effect of oleic acid includes dendritic differentiation and the expression of the neuronal basic helix-loop-helix transcription factor NeuroD2 (2004)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 88 (2004), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: We have shown recently that the presence of albumin in astrocytes triggers the synthesis and release of oleic acid, which behaves as a neurotrophic factor for neurons. Thus, oleic acid promotes axonal growth together with the expression of the axonal growth-associated protein, GAP-43. Here we attempted to elucidate whether the neurotrophic effect of oleic acid includes dendritic differentiation. Our results indicate that oleic acid induces the expression of microtubule associated protein-2 (MAP-2), a marker of dendritic differentiation. In addition, the presence of oleic acid promotes the translocation of MAP-2 from the soma to the dendrites. The time course of MAP-2 expression during brain development coincides with that of stearoyl-CoA desaturase, the limiting enzyme of oleic acid synthesis, indicating that both phenomena coincide during development. The effect of oleic acid on MAP-2 expression is most probably independent of autocrine factors synthesized by neurons because this effect was also observed at low cellular densities. As oleic acid is an activator of protein kinase C, the possible participation of this transduction pathway was studied. Our results indicate that added oleic acid or oleic acid endogenously synthesized by astrocytes exerts its neurotrophic effect through a protein kinase C-dependent mechanism as the effect was inhibited by sphingosine or two myristoylated peptide inhibitors of protein kinase C. The transduction pathway by which oleic acid induces the expression of genes responsible for neuronal differentiation appears to be mediated by the transcription factor NeuroD2, a regulator of terminal neuronal differentiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2003.02262.x
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  • 4
    Electronic Resource
    Electronic Resource
    Origins and effects of thermal processes on near-field optical probes (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 2597-2599 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An aluminum-coated tapered fiber probe, as used in near-field scanning optical microscopy (NSOM), is heated by the light coupled into it. This can destroy the probe or may modify the sample, which can be problematic or used as a tool. To study these thermal effects, we couple modulated visible light of various power through probes. Simultaneously coupled infrared light senses the thermal effects. We report their magnitude, their spatial and temporal scales, and real-time probe damage observations. A model describes the experimental data, the mechanisms for induced IR variation, and their relative importance. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.115143
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  • 5
    Electronic Resource
    Electronic Resource
    Optical imaging of carrier dynamics in silicon with subwavelength resolution (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 70 (1997), S. 1656-1658 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Characteristic rate variations of carrier processes are imaged using near-field scanning optical microscopy. We couple both a visible pump and an infrared probe light through a subwavelength aperture to investigate the interband recombination and intraband diffusion of excess carriers in oxidized silicon. Typical values of the locally measured life time constants agree well with those obtained by conventional space-averaged techniques. Moreover, the images locate defects, reveal variations, and can map the regions in which a recombination process is active. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.118661
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  • 6
    Electronic Resource
    Electronic Resource
    Adsorption and incorporation of silicon at GaN(0001) surfaces (2002)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 2008-2010 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied the adsorption and incorporation of Si at GaN(0001) surfaces employing density-functional theory and scanning tunneling microscopy (STM). Calculating the surface energy of a large number of structures with various Si concentrations and various III–V ratios, we derive a phase diagram showing the energetically most stable surfaces as a function of the Si and N chemical potentials. Based on these results, we identify the surface reconstructions seen in STM, explain the incorporation mechanism of Si on GaN surfaces, and discuss under which conditions Si acts as an antisurfactant. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1452785
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  • 7
    Electronic Resource
    Electronic Resource
    High strength, low dielectric constant fluorinated silica xerogel films (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 4010-4012 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The mechanical, electrical, and microstructural properties of low-k fluorinated silica xerogels produced using a one step spin-on process are reported. Derived from a fluorinated silane monomer, these films are easily processed and exhibit very low dielectric constants (2.1 as processed and 2.3 after heat treating at 450 °C in air). Structural determination by Fourier transform infrared spectrophotometry indicates a fluorinated silica structure with shortened Si–O bonds; however, some of the fluorine is lost during annealing. Nanoindentation studies show high elastic moduli (12 GPa) and hardness (1 GPa). Microstructural analyses by transmission and scanning electron microscopy indicate an unusual morphology with highly linked features and pore sizes in the 20–30 nm range. We believe the low dielectric constants and robust mechanical properties are due to the unusual microstructure of these films. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1418267
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  • 8
    Electronic Resource
    Electronic Resource
    H2O photodissociation dynamics based on potential energy surfaces from density functional calculations (1995)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 103 (1995), S. 2538-2547 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We investigate the usefulness of density functional theory (DFT) for calculating excited state potential energy surfaces. In the DFT calculations, the generalized gradient approximation (GGA) is used. As a test case, the photodissociation of H2O through the first excited A˜ 1B1 state was considered. Two-dimensional potential energy surfaces were obtained for both the X˜ 1A1 ground state and the first excited state. Wave packet calculations employing these surfaces were used to obtain both the absorption spectrum and partial photodissociation cross sections, which are resolved with respect to the final vibrational state of the OH fragment. Comparisons are made with a previously calculated high level ab initio potential energy surface, with dynamics calculations using that surface, and with experiment. The vertical excitation energy for the (X˜ 1A1→A˜ 1B1) transition calculated using DFT is in good agreement with the previous ab initio calculations. The absorption spectrum and the partial cross sections obtained with the DFT treatment are in good agreement with experiment. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.469675
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  • 9
    Electronic Resource
    Electronic Resource
    Apoptosis Susceptibility of Human Carcinoma and Leukemia Cell Lines to Taxol (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 784 (1996), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1996.tb16279.x
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  • 10
    Electronic Resource
    Electronic Resource
    Vitamin E blocks early events induced by 1-methyl-4-phenylpyridinium (MPP+) in cerebellar granule cells (2003)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 84 (2003), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Exposure of cerebellar granule cells (CGCs) to 1-methyl-4-phenylpyridinium (MPP+) results in apoptotic cell death, which is markedly attenuated by co-treatment of CGCs with the radical scavenger vitamin E. Analysis of free radical production and mitochondrial transmembrane potential (ΔΨm), using specific fluorescent probes, showed that MPP+ mediates early radical oxygen species (ROS) production without a loss of ΔΨm. Exposure to MPP+ also produces an early increase in Bad dephosphorylation and translocation of Bax to the mitochondria. These events are accompanied by cytochrome c release from mitochondria to cytosol, which is followed by caspase 3 activation. Exposure of the neurons to vitamin E maintains Bad phosphorylation and attenuates Bax translocation, inhibiting cytochrome c release and caspase activation. MPP+-mediated cytochrome c release is also prevented by allopurinol, suggesting the participation of xanthine oxidase in the process. Our results indicate that free radicals play an active role in the MPP+-induced early events that culminate with cell death.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2003.01520.x
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