775 resultados para Borel-Leroy summability
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"Contract number 105-78-1016."
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Mode of access: Internet.
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Mode of access: Internet.
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"References" at end of most of the chapters.
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Mode of access: Internet.
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Mode of access: Internet.
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Tau is a major microtubule-associated protein of axons and is also the principal component of the paired helical filaments (PHFs) that comprise the neurofibrillary tangles found in Alzheimer's disease and other tauopathies. Besides phosphorylation of tau on serine and threonine residues in both normal tau and tau from neurofibrillary tangles, Tyr-18 was reported to be a site of phosphorylation by the Src-family kinase Fyn. We examined whether tyrosine residues other than Tyr-18 are phosphorylated in tau and whether other tyrosine kinases might phosphorylate tau. Using mass spectrometry, we positively identified phosphorylated Tyr-394 in PHF-tau from an Alzheimer brain and in human fetal brain tau. When wild-type human tau was transfected into fibroblasts or neuroblastoma cells, treatment with pervanadate caused tau to become phosphorylated on tyrosine by endogenous kinases. By replacing each of the five tyrosines in tau with phenylalanine, we identified Tyr-394 as the major site of tyrosine phosphorylation in tau. Tyrosine phosphorylation of tau was inhibited by PP2 (4-amino-5-(4-chlorophenyl-7-(t-butyl) pyrazolo[3,4-d] pyrimidine), which is known to inhibit Src-family kinases and c-Abl. Cotransfection of tau and kinases showed that Tyr-18 was the major site for Fyn phosphorylation, but Tyr-394 was the main residue for Abl. In vitro, Abl phosphorylated tau directly. Abl could be coprecipitated with tau and was present in pretangle neurons in brain sections from Alzheimer cases. These results show that phosphorylation of tau on Tyr-394 is a physiological event that is potentially part of a signal relay and suggest that Abl could have a pathogenic role in Alzheimer's disease.
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Release of cytochrome c from mitochondria is a major event during apoptosis. Released cytochrome c has been shown to activate caspase-dependent apoptotic signals. In this report, we provide evidence for a novel role of cytochrome c in caspase-independent nuclear apoptosis. We showed that cytochrome c, released from mitochondria upon apoptosis induction, gradually accumulates in the nucleus as evidenced by both immunofluorescence and subcellular fractionation. Parallel to nuclear accumulation of cytochrome c, acetylated histone H2A, but not unmodified H2A, was released from the nucleus to the cytoplasm. Addition of purified cytochrome c to isolated nuclei recapitulated the preferential release of acetylated, but not deacetylated, histone H2A. Cytochrome c was also found to induce chromatin condensation. These results suggest that the nuclear accumulation of cytochrome c may be directly involved in the remodeling of chromatin. Our results provide evidence of a novel role for cytochrome c in inducing nuclear apoptosis.
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N-Heterocyclic cations are incorporated into proteins using 5-(2-bromoethyl)phenanthridinium bromide, which selectively reacts with either cysteine or lysine residues, resulting in ethylphenanthridinium (Phen) or highly stable cyclised dihydro-imidazo-phenanthridinium (DIP) adducts respectively; these modifications have been found to manipulate the observed structure of lysozyme and bovine serum albumin by AFM.
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Over the last few years governments, law enforcement agencies, and the media have noted increases of online harassment. Although there has been a great deal of research into 'offline stalking', at this moment in time there has been no formal research that attempts to classify cyberstalkers. This study aimed to identify a classification of cyberstalkers by interviewing victims. Twenty-four participants were interviewed and their responses logged on a 76-item Cyberstalking Incident Checklist. A typology of cyberstalkers was developed.
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This paper presents the first academic case study of a UK cyberstalking incident that involved an individual known to have harassed at least four victims. The case study describes how the harasser selected victims, his use of technology to gather confidential information about them and his use of multiple personalities as part of the process of harassment. The discussion section of the paper raises a broad range of issues, including whether the case represents a genuine cyberstalking incident, how technology was used to assist the harasser's activities and how the harasser attempted to avoid detection
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The advent of the internet has led to the new phenomenon of ‘cyberstalking’. This paper examines the extent of this problem. It is argued that all of the estimates commonly cited are flawed because they rely on inaccurate or outdated information or are based on a number of unproven assumptions. Although some estimates suggest that there may be as many as 10 million victims in the United States and Canada alone, available evidence supports a far smaller estimate. It is concluded that additional research is needed to arrive at more accurate and reliable estimates