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  • 1
    Electronic Resource
    Electronic Resource
    Two-color laser photoionization spectroscopy in a collisionless free-jet expansion: spectroscopy and excited-state dynamics of diazabicyclooctane (1984)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 88 (1984), S. 2250-2255 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j150655a015
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  • 2
    Electronic Resource
    Electronic Resource
    The gas phase reaction of C2H+2 with H2 below 3 K: The reopening of the bimolecular C2H+3 channel at low energy (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 96 (1992), S. 1121-1127 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The bimolecular reaction of C2H+2 with H2 is found to undergo a surprising change of mechanism to one of inverse energy dependence below temperatures of 3 K as observed in a free jet flow reactor. The observed rate coefficient for C2H+3 production is found to be k=5.6×10−11 T−2 cm3/s in this energy regime. Contrary to previous belief, the reaction is exothermic and results are described regarding kinetic isotope effects, the competitive three body association process and internal C2H+2 vibrational state dependency of the chemistry. A mechanism is suggested which involves a low temperature switching to a tunneling process through a small barrier and is intimately coupled to the long lived complex properties of very low energy collisions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.462198
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  • 3
    Electronic Resource
    Electronic Resource
    The low translational energy dependence of the reaction Ar+(2P3/2,1/2)+H2(D2) (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 96 (1992), S. 7440-7444 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We report the measurement of the spin–orbit state specific rate coefficients for the reactions Ar+(2P3/2,1/2)+H2(D2) at translational temperatures from 0.5 to 3 K in a free jet flow reactor. The measured rate coefficient for Ar+(2P3/2) with either H2 or D2 shows a slow monotonic increase with increasing collision energy from 4×10−5 to 10 eV. The observed kinetic isotope effect at low energy is consistent with the simple mass-dependent change in the collision frequency. Below 3 K, excitation into the 2P1/2 state is found to enhance the total reaction rate by a factor of 2.7 for the reaction with H2 and by 1.6 for the reaction with D2. The full range of energy-dependent experimental results are compared to current reaction models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.462394
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  • 4
    Electronic Resource
    Electronic Resource
    Gas phase atomic association reactions of Ar+, Kr+, and Xe+ at temperatures near 1 K (1992)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 96 (1992), S. 326-331 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We report the measurement of gas phase three-body atomic ion–atom association reaction rate coefficients at temperatures near 1 K using a free jet flow reactor. The association rate coefficients for the reactions of Ar+ with Ar and Ne, Kr+ with Kr and Ar, and the reactions of Xe+ with Xe, Kr, and Ar have been measured. In all these cases except Ar++Ne, the rate at 1 K is in excess of 9×10−29 cm3/s and a strong negative temperature dependence is observed. These observations are discussed with respect to several microscopic descriptions of the association process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.462520
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  • 5
    Electronic Resource
    Electronic Resource
    JKK1, an upstream activator of JNK/SAPK, is activated in Alzheimer's disease (2003)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 85 (2003), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: JNK/SAPK has been implicated in the pathogenesis of Alzheimer's disease, but the upstream cascade leading to JNK/SAPK activation has not been elucidated in the disease. In this study, we focused on one of the physiological activators of JNK/SAPK, JNK kinase 1 (JKK1). Although there was no significant difference in the level and distribution of total JKK1 between Alzheimer's disease (AD) and age-matched control cases, increased levels of activated phospho-JKK1 were specifically localized to neurofibrillary pathology including neurofibrillary tangles, senile plaque neurites, granulovaualar degenerations and neuropil threads in severe AD (Braak stage V–VI), considerably overlapping with its downstream effector, phospho-JNK/SAPK, suggesting both a functional and mechanistic link. Nuclear localization of phospho-JKK1 was also found in mild (Braak stage III–IV) but not in severe AD cases (Braak stage V–VI), suggesting a possible re-distribution correlating with the progress of the disease. By immunoblot analyses, phospho-JKK1 was significantly increased in AD over control cases. Together, these findings lend further credence to the notion that the JNK/SAPK pathway is dysregulated in AD and also indicate an active role for this pathway in disease pathogenesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2003.01645.x
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  • 6
    Electronic Resource
    Electronic Resource
    Induction of Heme Oxygenase-1 mRNA and Protein in Neocortex and Cerebral Vessels in Alzheimer's Disease (1995)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 65 (1995), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Previous studies demonstrated the specific association of heme oxygenase (HO)-1 protein to the neurofibrillary pathology of Alzheimer's disease (AD). In this study, we used reverse transcription-polymerase chain reaction methods to show the increased expression of HO-1 but not HO-2 mRNA transcripts in cerebral cortex and cerebral vessels from subjects with AD compared with age-matched non-AD controls. Neither the HO-1 nor the HO-2 mRNA level was altered in the cerebellum, a brain region usually spared from the pathological alterations of AD. There was no clear evidence that the expression of HO-1 in these tissues was related to postmortem interval, cause of death, or the age of the subjects studied. Using immunoblotting methods, we further showed that HO-1 protein content was increased in neocortical and vascular samples from AD subjects compared with controls. Our findings suggest the specific induction of HO-1 mRNA and protein in the cerebral cortex and cerebral vessels but not HO-2 mRNA or protein in association with the pathological lesions of the disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1995.65031399.x
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  • 7
    Electronic Resource
    Electronic Resource
    Carbonyl-Related Posttranslational Modification of Neurofilament Protein in the Neurofibrillary Pathology of Alzheimer's Disease (1995)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 64 (1995), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: We present the first evidence for carbonyl-related posttranslational modifications of neurofilaments in the neurofibrillary pathology of Alzheimer's disease (AD). Two distinct monoclonal antibodies that consistently labeled neurofibrillary tangles (NFTs), neuropil threads, and granulovacuolar degeneration in sections of AD tissue also labeled the neurofilaments within axons of the white matter following modification by reducing sugars, glutaraldehyde, formaldehyde, or malondialdehyde. The epitope recognized by these two antibodies shows a strict dependency for carbonyl modification of the neurofilament heavy subunit. The in vivo occurrence of this neurofilament modification in the neurofibrillary pathology of AD suggests that carbonyl modification is associated with a generalized cytoskeletal abnormality that may be critical in the pathogenesis of neurofibrillary pathology. Furthermore, the data presented here support the idea that extensive posttranslational modifications, including oxidative stress-type mechanisms, through the formation of cross-links, might account for the biochemical properties of NFTs and their resistance to degradation in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1995.64062660.x
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  • 8
    Electronic Resource
    Electronic Resource
    Activation and redistribution of c-Jun N-terminal kinase/stress activated protein kinase in degenerating neurons in Alzheimer's disease (2001)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 76 (2001), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Cellular responses to increased oxidative stress appear to be a mechanism that contributes to the varied cytopathology of Alzheimer's disease (AD). In this regard, we suspect that c-Jun N-terminal kinase/Stress activated protein kinase (JNK/SAPK), a major cellular stress response protein induced by oxidative stress, plays an important role in Alzheimer disease in susceptible neurons facing the dilemma of proliferation or death. We found that JNK2/SAPK-α and JNK3/SAPK-β were related to neurofibrillary pathology and JNK1/SAP-Kγ related to Hirano bodies in cases of AD but were only weakly diffuse in the cytoplasm in all neurons in control cases and in non-involved neurons in diseased brain. In this regard, in hippocampal and cortical regions of individuals with severe AD, the activated phospho-JNK/SAPK was localized exclusively in association with neurofibrillar alterations including neurofibrillary tangles, senile plaque neurites, neuropil threads and granulovacuolar degeneration structures (GVD), completely overlapping with τ-positive neurofibrillary pathology, but was virtually absent in these brain regions in younger and age-matched controls without pathology. However, in control patients with some pathology, as well as in mild AD cases, there was nuclear phospho-JNK/SAPK and translocation of phospho-JNK/SAPK from nuclei to cytoplasm, respectively, indicating that the activation and re-distribution of JNK/SAPK correlates with the progress of the disease. By immunoblot analysis, phospho-JNK/SAPK is significantly increased in AD over control cases. Together, these findings suggest that JNK/SAPK dysregulation, probably resulting from oxidative stress, plays an important role in the increased phosphorylation of cytoskeletal proteins found in AD.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2001.00046.x
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  • 9
    Electronic Resource
    Electronic Resource
    Induction of NADPH cytochrome P450 reductase by the Alzheimer β-protein. Amyloid as a ‘foreign body’ (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: A large body of data suggests that the Alzheimer's amyloid peptide (Aβ) causes degeneration and death of neurons by mechanisms that involve reactive oxygen species. The pathways involved in Aβ-mediated oxidative injury are only partially understood. We theorized that abnormal microaggregates and/or pathological conformations of Aβ peptides may behave as xenobiotics and trigger the induction of NADPH cytochrome P450 reductase (CP450r), an enzyme which, if induced by non-physiological substrates (such as xenobiotics like drugs or other ‘foreign molecules’), is known to cause oxidative stress. In order to test this hypothesis, i.e. that Aβ can increase the expression of CP450r, SK-N-SH human neuroblastoma cells were exposed to Aβ25-35 and Aβ1-42 and then examined for induction of this enzyme in immunoblots, using specific antibodies. Following exposure to Aβ peptides, neuroblastoma cells showed a clear-cut induction of CP450r. To determine whether this mechanism is operational in vivo, we investigated the expression of CP450r in a transgenic mouse model of Alzheimer's disease (AD) and in brains from patients afflicted with AD, using an immunocytochemical approach. Tissue sections from brains of transgenic mice exhibited strong immunoreactivity for CP450r, surrounding amyloid deposits. The pattern of expression of CP450r was similar to that exhibited by neuritic and oxidative stress markers. Sections from non-transgenic mice showed no detectable immunoreactivity. Immunostaining of sections from four brains with neuropathologically confirmed AD showed a pattern of abnormality different from transgenic mice that was characterized by abnormal immunoreactivity for CP450r within the cytoplasm of cortical neurons. No labeling was seen in sections from aged-matched control brains. The data showed that CP450r is induced by Alzheimer amyloid peptide and that such a response must be considered as one possible mechanism whereby Aβ causes oxidative stress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2001.00379.x
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  • 10
    Electronic Resource
    Electronic Resource
    Amyloid-β Deposition in Alzheimer Transgenic Mice Is Associated with Oxidative Stress (1998)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 70 (1998), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Increased awareness for a role of oxidative stress in the pathogenesis of Alzheimer's disease has highlighted the issue of whether oxidative damage is a fundamental step in the pathogenesis or instead results from disease-associated pathology. In vitro experiments support both possibilities: Oxidative stress increases amyloid-β production, and, conversely, amyloid-β increases oxidative damage. To address the relationship between amyloid-β and oxidative stress in vivo, we examined, using an array of oxidative markers, transgenic mice that overexpress amyloid-β precursor protein and, as in Alzheimer's disease, develop characteristic amyloid-β deposits within the brain parenchyma. Transgenic animals show the same type of oxidative damage that is found in Alzheimer's disease, and it is important that this damage directly correlates with the presence of amyloid-β deposits. The significance of these studies is twofold. First, they provide evidence that amyloid-β and oxidative damage are inextricably linked in vivo. Second, they support the use of transgenic animals for the development of antioxidant therapeutic strategies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1998.70052212.x
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